WorldWideScience

Sample records for calcined aggregates

  1. [Based on Curing Age of Calcined Coal Gangue Fine Aggregate Mortar of X-Ray Diffraction and Scanning Electron Microscopy Analysis].

    Science.gov (United States)

    Dong, Zuo-chao; Xia, Jun-wu; Duan, Xiao-mu; Cao, Ji-chang

    2016-03-01

    By using X-ray diffraction (XRD) and environmental scanning electron microscope (SEM) analysis method, we stud- ied the activity of coal gangue fine aggregate under different calcination temperature. In view of the activity of the highest-700 degrees C high temperature calcined coal gangue fine aggregate mortar of hydration products, microstructure and strength were discussed in this paper, and the change laws of mortar strength with curing age (3, 7, 14, 28, 60 and 90 d) growth were analyzed. Test results showed that coal gangue fine aggregate with the increase of calcination temperature, the active gradually increases. When the calcination temperature reaches 700 degrees C, the activity of coal gangue fine aggregate is the highest. When calcining temperature continues to rise, activity falls. After 700 degrees C high temperature calcined coal gangue fine aggregate has obvious ash activity, the active components of SiO2 and Al2 O3 can be with cement hydration products in a certain degree of secondary hydration reaction. Through on the top of the activity of different curing age 700 degrees C high temperature calcined coal gangue fine aggregate mortar, XRD and SEM analysis showed that with the increase of curing age, secondary hydration reaction will be more fully, and the amount of hydration products also gradually increases. Compared with the early ages of the cement mortar, the products are more stable hydration products filling in mortar microscopic pore, which can further improve the microstructure of mortar, strengthen the interface performance of the mortar. The mortar internal structure is more uniform, calcined coal gangue fine aggregate and cement mortar are more of a strong continuous whole, which increase the later strength of hardened cement mortar, 700 degrees C high temperature calcined coal gangue fine aggregate pozzolanic effect is obvious.

  2. Study of the behavior of aggregate of calcined clay for use in permeable pavements for the city of Manaus; Estudo do comportamento de agregado sintetico de argila calcinada para uso em pavimentos permeaveis para a cidade de Manaus

    Energy Technology Data Exchange (ETDEWEB)

    Oliveira, M.S.; Vilela, P.A.T.; Araujo, V.S., E-mail: oliveirasmichelle@gmail.com [Universidade do Estado do Amazonas (UEAM), AM (Brazil)

    2016-07-01

    Research on the production of ceramic aggregates and their use in paving in the country began in the 80’s in the search for an alternative material that could replace the pebble or crushed stone, studied the clay, considered an abundant mineral resource by virtue of being the predominant soil in this region and which were made synthetic calcinated clay aggregates (ASAC), for their application in permeable paving concrete motivated by the lack of permeable areas. The study consists of the characterization of materials for manufacture of concrete slabs permeable and the assessment of the effects of synthetic aggregate on its properties in fresh and hardened state. The ceramic bodies were subjected to tests of X-ray diffraction, determination of chemical composition and plasticity. The results indicate that the use of synthetic clusters is a viable alternative for the production of porous concrete. (author)

  3. Enrichment Of Calcined Magnesite

    OpenAIRE

    GENCE, Nermin

    2017-01-01

    In this study, the possibility ofconcentration of magnesite are which contains high dolomite, low iron andsiliceous gangue was investigated by heavy medium separation, shaking table and vashing-screeningafter calcination.

  4. Desempenho mecânico de misturas asfálticas confeccionadas com agregados sintéticos de argila calcinada Mechanical performance of asphalt mixtures composed of synthetic calcinated clay aggregates

    Directory of Open Access Journals (Sweden)

    C. A. Frota

    2007-09-01

    .A substantial number of municipal districts in the State of Amazonas are located in areas which are poor in stony materials. And this has led pavement builders into adopting alternatives which have historically produced pavements with low mechanical strength. Whist more effective and appropriate from a technical standpoint, the asphalt concrete has been usually left aside due to the referred lack of stony materials. Because of the specific situation in the State of Amazonas the adoption of synthetic calcinated clay aggregates (SCCA, with an abundant raw material (clay in the State of Amazonas is recommended in lieu of the traditional practice. Previous works carried out by the Federal University of Amazonas Geotechny Group have demonstrated that the clay soil commonly used in the production of ceramic materials can yield synthetic aggregates with adequate mechanical properties. In this research work, samples featuring similar characteristics as those of the soils in question have been found along the BR-319 highway connecting the Manaus (AM city to Porto Velho (RO city. The transportation structure in general is in deplorable conditions. Justifiably so, the recovery of this highway has been earmarked as one of the targets for the Ministry of Transportation. In this study, asphalt mixtures were blended with synthetic aggregates and pebbles taken from the river bed in order to compare the mechanical performance of such mixtures by means of the determination of the resilient modulus (RM. The results, as a rule, have shown that the asphalt mixtures comprising synthetic calcinated clay aggregates when compared with those comprising the naturally-found material (river bed pebbles have shown: (a greater tensile and resilient modulus strengths; (b low deformation tendency, as well as a considerable elastic recovery and (c less susceptibility to permanent deformation.

  5. Dissolution Kinetics of Alumina Calcine

    Energy Technology Data Exchange (ETDEWEB)

    Batcheller, Thomas Aquinas

    2001-09-01

    Dissolution kinetics of alumina type non-radioactive calcine was investigated as part of ongoing research that addresses permanent disposal of Idaho High Level Waste (HLW). Calcine waste was produced from the processing of nuclear fuel at the Idaho Nuclear Technology and Engineering Center (INTEC). Acidic radioactive raffinates were solidified at ~500°C in a fluidized bed reactor to form the dry granular calcine material. Several Waste Management alternatives for the calcine are presented in the Idaho High Level Waste Draft EIS. The Separations Alternative addresses the processing of the calcine so that the HLW is ready for removal to a national geological repository by the year 2035. Calcine dissolution is the key front-end unit operation for the separations alternative.

  6. Investigation on Calcination Behaviors of Coal Gangue by Fluidized Calcination in Comparison with Static Calcination

    Directory of Open Access Journals (Sweden)

    Shuai Yuan

    2017-02-01

    Full Text Available In order to comprehensively utilize coal gangue, we present fluidized calcination as a new thermal technology for activating coal gangue and systematical study was conducted in comparison with static calcination. The calcined products obtained by different calcination methods under various temperatures were characterized by the means of X-ray diffraction (XRD, thermal gravimetry-differential scanning calorimeter (TG-DSC, Fourier transform-infrared spectroscopy (FT-IR and scanning electron microscope-energy dispersive spectrometer (SEM-EDS. Chemical and physical characteristics such as aluminium leaching rate, chemical oxygen demand and whiteness of calcined products were also investigated. The results show that aluminium leaching rate could reach to the maximal value 74.42% at 500 °C by fluidized calcination, while the maximal value of 66.33% could be reached at 600 °C by static calcination. Products by fluidized calcination obtained higher whiteness and lower chemical oxygen demand (COD under the same calcination temperature. The well-crystallized kaolinite transform to amorphous meta-kaolinite under 600 °C and mullite presence under 1000 °C according to phase transformation, chemical bond variation and microstructure evolution analysis. Fluidized calcination was more efficiently for combustion of carbon/organic matter and dehydroxylation of kaolinite, which might applied in coal gangue industry in future.

  7. Crystallographic transformation of limestone during calcination under CO2.

    Science.gov (United States)

    Valverde, Jose Manuel; Medina, Santiago

    2015-09-14

    The calcination reaction of limestone (CaCO3) to yield lime (CaO) is at the heart of many industrial applications as well as natural processes. In the recently emerged calcium-looping technology, CO2 capture is accomplished by the carbonation of CaO in a gas-solid reactor (carbonator). CaO is derived by the calcination of limestone in a calciner reactor under necessarily high CO2 partial pressure and high temperature. In situ X-ray diffraction (XRD) has been employed in this work to gain further insight into the crystallographic transformation that takes place during the calcination of limestone under CO2, at partial pressures (P) close to the equilibrium pressure (Peq) and at high temperature. Calcination under these conditions becomes extremely slow. The in situ XRD analysis presented here suggests the presence of an intermediate metastable CaO* phase stemming from the parent CaCO3 structure. According to the reaction mechanism proposed elsewhere, the exothermicity of the CaO* → CaO transformation and high values of P/Peq inhibit the nucleation of CaO at high temperatures. The wt% of CaO* remains at a relatively high level during slow calcination. Two diverse stages have been identified in the evolution of CaO crystallite size, L. Initially, L increases with CaCO3 conversion, following a logarithmic law. Slow calcination allows the crystallite size to grow up from a few nanometers at nucleation up to around 100 nm near the end of conversion. Otherwise, quick calcination at relatively lower CO2 concentrations limits CaO crystallite growth. Once calcination reaches an advanced state, the presence of CaO* drops to zero and the rate of increase of the CaO crystallite size is significantly hindered. Arguably, the first stage in CaO crystallite growth is driven by aggregation of the metastable CaO* nanocrystals, due to surface attractive forces, whereas the second one is consistent with sintering of the aggregated CaO crystals, and persists with time after full

  8. SPRAY CALCINATION REACTOR

    Science.gov (United States)

    Johnson, B.M.

    1963-08-20

    A spray calcination reactor for calcining reprocessin- g waste solutions is described. Coaxial within the outer shell of the reactor is a shorter inner shell having heated walls and with open regions above and below. When the solution is sprayed into the irner shell droplets are entrained by a current of gas that moves downwardly within the inner shell and upwardly between it and the outer shell, and while thus being circulated the droplets are calcined to solids, whlch drop to the bottom without being deposited on the walls. (AEC) H03 H0233412 The average molecular weights of four diallyl phthalate polymer samples extruded from the experimental rheometer were redetermined using the vapor phase osmometer. An amine curing agent is required for obtaining suitable silver- filled epoxy-bonded conductive adhesives. When the curing agent was modified with a 47% polyurethane resin, its effectiveness was hampered. Neither silver nor nickel filler impart a high electrical conductivity to Adiprenebased adhesives. Silver filler was found to perform well in Dow-Corning A-4000 adhesive. Two cascaded hot-wire columns are being used to remove heavy gaseous impurities from methane. This purified gas is being enriched in the concentric tube unit to approximately 20% carbon-13. Studies to count low-level krypton-85 in xenon are continuing. The parameters of the counting technique are being determined. The bismuth isotopes produced in bismuth irradiated for polonium production are being determined. Preliminary data indicate the presence of bismuth207 and bismuth-210m. The light bismuth isotopes are probably produced by (n,xn) reactions bismuth-209. The separation of uranium-234 from plutonium-238 solutions was demonstrated. The bulk of the plutonium is removed by anion exchange, and the remainder is extracted from the uranium by solvent extraction techniques. About 99% of the plutonium can be removed in each thenoyltrifluoroacetone extraction. The viscosity, liquid density, and

  9. Alternative calcination development status report

    Energy Technology Data Exchange (ETDEWEB)

    Boardman, R.D.

    1997-12-01

    The Programmatic Spent Nuclear Fuel and (INEEL) Environmental Restoration and Waste Management Programs Environmental Impact Statement Record of Decision, dated June 1, 1995, specifies that high-level waste stored in the underground tanks at the ICPP continue to be calcined while other options to treat the waste are studied. Therefore, the High-Level Waste Program has funded a program to develop new flowsheets to increase the liquid waste processing rate. Simultaneously, a radionuclide separation process, as well as other options, are also being developed, which will be compared to the calcination treatment option. Two alternatives emerged as viable candidates; (1) elevated temperature calcination (also referred to as high temperature calcination), and (2) sugar-additive calcination. Both alternatives were determined to be viable through testing performed in a lab-scale calcination mockup. Subsequently, 10-cm Calciner Pilot Plant scoping tests were successfully completed for both flowsheets. The results were compared to the standard 500 C, high-ANN flow sheet (baseline flowsheet). The product and effluent streams were characterized to help elucidate the process chemistry and to investigate potential environmental permitting issues. Several supplementary tests were conducted to gain a better understanding of fine-particles generation, calcine hydration, scrub foaming, feed makeup procedures, sugar/organic elimination, and safety-related issues. Many of the experiments are only considered to be scoping tests, and follow-up experiments will be required to establish a more definitive understanding of the flowsheets. However, the combined results support the general conclusion that flowsheet improvements for the NWCF are technically viable.

  10. The Properties of Calcined Anthracite

    OpenAIRE

    Holm, Katrine

    2017-01-01

    The aim of this thesis has been to look at the thermal behaviour of anthracite, coke and charcoal regarding their expansion during heating and their release of off-gases. Furthermore, to look at how the porosity and expansion of the anthracite is affected by the different temperatures during the calcining process. Two anthracites (A11 and A19), two cokes (C3 and C7) and one charcoal (BIO) were investigated. The porosity and surface area of A11 calcined at different temperatures were inves...

  11. Summary of Waste Calcination at INTEC

    Energy Technology Data Exchange (ETDEWEB)

    O' Brien, Barry Henry; Newby, Bill Joe

    2000-10-01

    Fluidized-bed calcination at the Idaho Nuclear Technologies and Engineering Center (INTEC, formally called the Idaho Chemical Processing Plant) has been used to solidify acidic metal nitrate fuel reprocessing and incidental wastes wastes since 1961. A summary of waste calcination in full-scale and pilot plant calciners has been compiled for future reference. It contains feed compositions and operating conditions for all the processing campaigns for the original Waste Calcining Facility (WCF), the New Waste Calcining Facility (NWCF) started up in 1982, and numerous small scale pilot plant tests for various feed types. This summary provides a historical record of calcination at INTEC, and will be useful for evaluating calcinability of future wastes.

  12. XANES analysis of dried and calcined bones

    Energy Technology Data Exchange (ETDEWEB)

    Rajendran, Jayapradhi [Materials Science and Engineering Department, University of Texas at Arlington (United States); Gialanella, Stefano [Materials Science and Industrial Technology Department, University of Trento (Italy); Aswath, Pranesh B., E-mail: aswath@uta.edu [Materials Science and Engineering Department, University of Texas at Arlington (United States)

    2013-10-15

    The structure of dried and calcined bones from chicken, bovine, deer, pig, sheep and chamois was examined using X-ray Absorption Near Edge Structure (XANES) spectroscopy. The oxygen K-edge absorption edge indicates that the surface of dried bone has a larger proportion of carbonate than the interior that is made up of phosphates. The phosphorus L and K edge clearly indicate that pyrophosphates, α-tricalcium phosphate (α-TCP) and hydrogen phosphates of Ca do not exist in either the dried bone or calcined bone and phosphorus exists as either β-tricalcium phosphate (β-TCP) or hydroxyapatite, both in the dried and calcined conditions. The Ca K-edge analysis indicates that β-TCP is the likely form of phosphate in both the dried and calcined conditions. - Highlights: • For the first time bones of five different species of vertebrates have been compared in both the dried and calcined states. • O, P and Ca edges detail the local coordination of these atoms in dried and calcined bone. • O K-edge shows that the surface of bone has more CO{sub 3} while the interior has more PO{sub 4}. • P and Ca edges eliminate the presence of pyrophosphates and confirmed the presence of HA and β-TCP. • The stability of these phosphates on calcination has been examined using XANES.

  13. Calcined solids storage facility closure study

    Energy Technology Data Exchange (ETDEWEB)

    Dahlmeir, M.M.; Tuott, L.C.; Spaulding, B.C. [and others

    1998-02-01

    The disposal of radioactive wastes now stored at the Idaho National Engineering and Environmental Laboratory is currently mandated under a {open_quotes}Settlement Agreement{close_quotes} (or {open_quotes}Batt Agreement{close_quotes}) between the Department of Energy and the State of Idaho. Under this agreement, all high-level waste must be treated as necessary to meet the disposal criteria and disposed of or made road ready to ship from the INEEL by 2035. In order to comply with this agreement, all calcined waste produced in the New Waste Calcining Facility and stored in the Calcined Solids Facility must be treated and disposed of by 2035. Several treatment options for the calcined waste have been studied in support of the High-Level Waste Environmental Impact Statement. Two treatment methods studied, referred to as the TRU Waste Separations Options, involve the separation of the high-level waste (calcine) into TRU waste and low-level waste (Class A or Class C). Following treatment, the TRU waste would be sent to the Waste Isolation Pilot Plant (WIPP) for final storage. It has been proposed that the low-level waste be disposed of in the Tank Farm Facility and/or the Calcined Solids Storage Facility following Resource Conservation and Recovery Act closure. In order to use the seven Bin Sets making up the Calcined Solids Storage Facility as a low-level waste landfill, the facility must first be closed to Resource Conservation and Recovery Act (RCRA) standards. This study identifies and discusses two basic methods available to close the Calcined Solids Storage Facility under the RCRA - Risk-Based Clean Closure and Closure to Landfill Standards. In addition to the closure methods, the regulatory requirements and issues associated with turning the Calcined Solids Storage Facility into an NRC low-level waste landfill or filling the bin voids with clean grout are discussed.

  14. Modeling and control of a calcination furnace

    OpenAIRE

    Wilson, Øyvind

    2017-01-01

    Calcined anthracite is the primary material used in Søderberg electrode paste, prebaked carbon electrodes, aluminium cathodes, and a variety of other carbon products used in the metallurgical industries. In electrical calcination of anthracite current is passed through the raw material. This heat treats the anthracite, which gets rid of volatile matter and water, and graphitizes the anthracite. The graphitization lower the anthracite's electrical resistivity. The object of the process is...

  15. Bin Set 1 Calcine Retrieval Feasibility Study

    Energy Technology Data Exchange (ETDEWEB)

    R. D. Adams; S. M. Berry; K. J. Galloway; T. A. Langenwalter; D. A. Lopez; C. M. Noakes; H. K. Peterson; M. I. Pope; R. J. Turk

    1999-10-01

    At the Department of Energy's Idaho Nuclear Technology and Engineering Center, as an interim waste management measure, both mixed high-level liquid waste and sodium bearing waste have been solidified by a calculation process and are stored in the Calcine Solids Storage Facilities. This calcined product will eventually be treated to allow final disposal in a national geologic repository. The Calcine Solids Storage Facilities comprise seven ''bit sets.'' Bin Set 1, the first to be constructed, was completed in 1959, and has been in service since 1963. It is the only bin set that does not meet current safe-shutdown earthquake seismic criteria. In addition, it is the only bin set that lacks built-in features to aid in calcine retrieval. One option to alleviate the seismic compliance issue is to transport the calcine from Bin Set 1 to another bin set which has the required capacity and which is seismically qualified. This report studies the feasibility of retrieving the calcine from Bi n Set 1 and transporting it into Bin Set 6 which is located approximately 650 feet away. Because Bin Set 1 was not designed for calcine retrieval, and because of the high radiation levels and potential contamination spread from the calcined material, this is a challenging engineering task. This report presents preconceptual design studies for remotely-operated, low-density, pneumatic vacuum retrieval and transport systems and equipment that are based on past work performed by the Raytheon Engineers and Constructors architectural engineering firm. The designs presented are considered feasible; however, future development work will be needed in several areas during the subsequent conceptual design phase.

  16. 1st International Conference on Calcined Clays for Sustainable Concrete

    CERN Document Server

    Favier, Aurélie

    2015-01-01

    This volume focuses on research and practical issues linked to Calcined Clays for Sustainable Concrete. The main subjects are geology of clays, hydration and performance of blended systems with calcined clays, alkali activated binders, economic and environmental impacts of the use of calcined clays in cement based materials. Topics addressed in this book include the influence of processing on reactivity of calcined clays, influence of clay mineralogy on reactivity, geology of clay deposits, Portland-calcined clay systems, hydration, durability, performance, Portland-calcined clay-limestone systems, hydration, durability, performance, calcined clay-alkali systems, life cycle analysis, economics and environmental impact of use of calcined clays in cement and concrete, and field applications. This book compiles the different contributions of the 1st International Conference on Calcined Clays for Sustainable Concrete, which took place in Lausanne, Switzerland, June, 23-25, 2015.The papers present the latest  res...

  17. Dissolution Studies With Pilot Plant and Actual INTEC Calcines

    Energy Technology Data Exchange (ETDEWEB)

    Herbst, Ronald Scott; Garn, Troy Gerry

    1999-04-01

    The dissolution of Idaho Nuclear Technology and Engineering Center (INTEC) pilot plant calcines was examined to determine solubility of calcine matrix components in acidic media. Two representatives pilot plant calcine types were studied: Zirconia calcine and Zirconia/ Sodium calcine. Dissolution of these calcines was evaluated using lower initial concentrations of nitric acid than used in previous tests to decrease the [H+] concentration in the final solutions. Lower [H+] concentrations contribute to more favorable TRUEX/SREX solvent extraction flowsheet performance. Dissolution and analytical results were also obtained for radioactive calcines produced using high sodium feeds blended with non-radioactive A1(NO3)3 solutions to dilute the sodium concentration and prevent bed agglomeration during the calcination process. Dissolution tests indicated >95 wt. % of the initial calcine mass can be dissolved using the baseline dissolution procedure, with the exception that higher initial nitric acid concentrations are required. The higher initial acid concentration is required for stoichiometric dissolution of the oxides, primarily aluminum oxide. Statistically designed experiments using pilot plant calcine were performed to determine the effect of mixing rate on dissolution efficiency. Mixing rate was determined to provide minimal effects on wt. % dissolution. The acid/calcine ratio and temperature were the predominate variables affecting the wt. % dissolution, a result consistent with previous studies using other similar types of pilot plant calcines.

  18. Calcination of calcium carbonate and blend therefor

    Science.gov (United States)

    Mallow, William A.; Dziuk, Jr., Jerome J.

    1989-01-01

    A method for calcination of a calcium carbonate material comprising heating the calcium carbonate material to a temperature and for a time sufficient to calcine the material to the degree desired while in the presence of a catalyst; said catalyst comprising at least one fused salt having the formula MCO.sub.3.CaCO.sub.3.CaO.H.sub.2 O.sub.x, wherein M is an alkali metal and x is 0 to 1 and formed by fusing MCO.sub.3 and CaCO.sub.3 in a molar ratio of about 1:2 to 2:1, and a blend adapted to be heated to CaO comprising a calcium carbonate material and at least one such fused salt.

  19. Comparison of Dolomite Crystal Structure, Calcinations Dolomite and Magnesium Hydroxide in Partial Calcinations and Slaking Process

    Science.gov (United States)

    Sulistiyono, E.; Firdiyono, F.; Natasha, NC; Amalia, Y.

    2017-02-01

    Dolomite is a mineral that consists of calcium carbonate and magnesium carbonate with various mole ratio depend on the formation of mineral source. Recently, Utilization of dolomite only used as raw material for fertilizer and building materials, so that the enhancement of its added value becomes low. If the components in dolomite can be separated, magnesium carbonate and calcium carbonate will be produced then provide high added value. To separate these two components in dolomite is through partial calcinations followed by slaking process. The purpose of this paper is to prove that the partial calcinations can be used as a fundamental process for calcium and magnesium separation process in dolomite. SEM-EDX and XRD analysis proved that partial calcinations at 675°C for 6 hours is able to produce magnesium oxide (MgO) and calcium oxide (CaO). Then sea water was added to calcinations product so magnesium hydroxide and calcium carbonate that easily separated by sea water. The weakness of partial calcinations process at 675°C and processing time 2 hours is the dolomite has not perfectly reacted yet. XRD analysis showed that MgCO3. CaCO3 compounds still exist, so there is a possibility that magnesium was not fetched after the separation process.

  20. Calcination of kaolinite clay particles for cement production

    DEFF Research Database (Denmark)

    Gebremariam, Abraham Teklay; Yin, Chungen; Rosendahl, Lasse

    2014-01-01

    Kaolinite rich clay particles calcined under certain conditions can attain favorable pozzolanic properties and can be used to substitute part of the CO2 intensive clinker in cement production. To better guide calcination of a clay material, a transient one-dimensional single particle model...

  1. Study of as-synthesized and calcined hydrocalumites as possible ...

    Indian Academy of Sciences (India)

    Administrator

    properties, when it is calcined at different temperatures. Thus, for ... controlling the pH in the stomach. They could act as neu- tralizing of stomach acidity and maintaining an adequate. pH in the stomach. Normally, such antacids can be for- mulated as ... calcine at different temperatures Ca/Al hydrocalumite- type solids for ...

  2. Effect of Calcination and Reduction Temperatures on the Reduction ...

    African Journals Online (AJOL)

    The effect of calcination and reduction temperatures on the reducibility, dispersion and Fischer-Tropsch activity of 10 wt% cobalt supported on titania catalyst modified by 0.1 wt% boron has been studied. The percentage reduction and percentage dispersion were found to decrease with increasing calcination temperature.

  3. Characterization and Dissolution Kinetics Testing of Radioactive H-3 Calcine

    Energy Technology Data Exchange (ETDEWEB)

    Garn, Troy Gerry; Batcheller, Thomas Aquinas

    2002-09-01

    Characterization and dissolution kinetics testing were performed with Idaho radioactive H-3 calcine. Calcine dissolution is the key front-end unit operation for the Separations Alternative identified in the Idaho High Level Waste Draft EIS. The impact of the extent of dissolution on the feasibility of Separations must be clearly quantified.

  4. Calcined clay lightweight ceramics made with wood sawdust and sodium silicate

    Energy Technology Data Exchange (ETDEWEB)

    Santis, Bruno Carlos de; Rossignolo, Joao Adriano, E-mail: desantis.bruno@gmail.com [Universidade de Sao Paulo (USP), Pirassununga, SP (Brazil); Morelli, Marcio Raymundo [Universidade Federal de Sao Carlos (UFSCar), SP (Brazil). Departamento de Engenharia de Materiais

    2016-11-15

    This paper aims to study the influence of including wood sawdust and sodium silicate in the production process of calcined clay lightweight ceramics. In the production process first, a sample used by a company that produces ceramic products in Brazil was collected. The sample was analysed by techniques of liquidity (LL) and plasticity (LP) limits, particle size analysis, specific mass, X-ray diffraction (XRD) and X ray fluorescence spectrometry (XRF). From the clay, specimens of pure clay and mixtures with wood sawdust (10%, 20% and 30% by mass) and sodium silicate were produced and fired at a temperature of 900 deg C. These specimens were submitted to tests of water absorption, porosity, specific mass and compressive strength. Results of this research indicate that the incorporation of wood sawdust and sodium silicate in the ceramic paste specimens can be useful to make calcined clay lightweight ceramics with special characteristics (low values of water absorption and specific mass and high values of compressive strength), which could be used to produce calcined clay lightweight aggregates to be used in structural concrete. (author)

  5. Flash calcination of kaolinite rich clay and impact of process conditions on the quality of the calcines

    DEFF Research Database (Denmark)

    Gebremariam, Abraham Teklay; Yin, Chungen; Rosendahl, Lasse

    2016-01-01

    Use of properly calcined kaolinite rich clay (i.e., metakaolin) to offset part of CO2-intensive clinkers not only reduces CO2 footprint from cement industry but also improves the performance of concrete. However, calcination under inappropriately high temperatures or long retention times may...

  6. Summary of Calcine Disposal Development Using Hot Isostatic Pressing

    Energy Technology Data Exchange (ETDEWEB)

    Bateman, Ken [Idaho National Lab. (INL), Idaho Falls, ID (United States); Wahlquist, Dennis [Idaho National Lab. (INL), Idaho Falls, ID (United States); Hart, Edward [Idaho National Lab. (INL), Idaho Falls, ID (United States); McCartin, William [Idaho National Lab. (INL), Idaho Falls, ID (United States)

    2015-03-01

    Battelle Energy Alliance, LLC, has demonstrated the effectiveness of the hot isostatic press (HIP) process for treatment of hazardous high-level waste known as calcine that is stored at the Idaho Nuclear Technology and Engineering Center (INTEC) at Idaho National Laboratory. HIP trials performed with simulated calcines at Idaho National Laboratory’s Materials and Fuels Complex and an Australian Nuclear Science and Technology Organization facility from 2007 to 2010 produced a dense, monolithic waste form with increased chemical durability and effective (storage) volume reductions of ~10 to ~70% compared to granular calcine forms. In December 2009, the U.S. Department of Energy signed an amended Record of Decision selecting HIP technology as the treatment method for the 4,400 m3 of granular zirconia and alumina calcine stored at INTEC. Testing showed that HIP treatment reduces the risks associated with radioactive and hazardous constituent release, post-production handling, and long-term (repository) storage of calcines and would result in estimated storage cost savings in the billions of dollars. Battelle Energy Alliance has the ability to complete pilot-scale HIP processing of INTEC calcine, which is the next necessary step in implementing HIP processing as a calcine treatment method.

  7. Assessment of soda ash calcination treatment of Turkish trona ore

    Directory of Open Access Journals (Sweden)

    Gezer Sibel

    2016-01-01

    Full Text Available Trona is relatively rare, non-metallic mineral, Na2CO3 · NaHCO3 · 2H2O. The pure material contains 70.3% sodium carbonate and by calcination the excess CO2 and water can be driven off, yielding natural soda ash. The terms soda ash and sodium carbonate are used interchangeably. Trona calcining is a key process step in production of soda ash (sodium carbonate anhydrate from the relatively cheap trona ore. The calcination reaction may proceeds in a sequence of steps. Depending on the conditions, it may result in formation of either sodium carbonate monohydrate (Na2CO3 · H2O, sodium sesquicarbonate or weigschederite (Na2CO3 · 3NaHCO3. The Beypazarı Turkish trona deposit is the second largest deposit in the world with the content of 84% trona. The decomposition of trona appeared to be a single stage process across the temperature range studied (150-200 °C with the representative samples of different size fractions in the draught up metallurgical furnace. The optimum particle size and calcination time were −6.35 mm and 30 minutes, respectively, at calcination temperature of 175 °C in a metallurgical furnace. Microwave-induced dry calcination of trona was possible and 5 minutes of calcination time at a power level of 900 was sufficient for complete calcination of −6.35 mm feed. This includes short time calcinations with the goal of improving economics and simplifying the thermal process.

  8. Structural Integrity Program for INTEC Calcined Solids Storage Facilities

    Energy Technology Data Exchange (ETDEWEB)

    Jeffrey Bryant

    2008-08-30

    This report documents the activities of the structural integrity program at the Idaho Nuclear Technology and Engineering Center relevant to the high-level waste Calcined Solids Storage Facilities and associated equipment, as required by DOE M 435.1-1, 'Radioactive Waste Management Manual'. Based on the evaluation documented in this report, the Calcined Solids Storage Facilities are not leaking and are structurally sound for continued service. Recommendations are provided for continued monitoring of the Calcined Solids Storage Facilities.

  9. Calcine Waste Storage at the Idaho Nuclear Technology and Engineering Center

    Energy Technology Data Exchange (ETDEWEB)

    Staiger, Merle Daniel; M. C. Swenson

    2005-01-01

    This report documents an inventory of calcined waste produced at the Idaho Nuclear Technology and Engineering Center during the period from December 1963 to May 2000. The report was prepared based on calciner runs, operation of the calcined solids storage facilities, and miscellaneous operational information that establishes the range of chemical compositions of calcined waste stored at Idaho Nuclear Technology and Engineering Center. The report will be used to support obtaining permits for the calcined solids storage facilities, possible treatment of the calcined waste at the Idaho National Engineering and Environmental Laboratory, and to ship the waste to an off-site facility including a geologic repository. The information in this report was compiled from calciner operating data, waste solution analyses and volumes calcined, calciner operating schedules, calcine temperature monitoring records, and facility design of the calcined solids storage facilities. A compact disk copy of this report is provided to facilitate future data manipulations and analysis.

  10. Calcinated egg shell as a candidate of biosecurity enhancement material

    National Research Council Canada - National Science Library

    OTA, Mari; TOYOFUKU, Chiharu; THAMMAKARN, Chanathip; SANGSRIRATANAKUL, Natthanan; YAMADA, Masashi; NAKAJIMA, Katsuhiro; KITAZAWA, Minori; HAKIM, Hakimullah; ALAM, Md. Shahin; SHOHAM, Dany; TAKEHARA, Kazuaki

    2016-01-01

    Calcinated egg shell (Egg-CaO), of which the main component is calcium oxide, was evaluated in the forms of powder and aqueous solutions for their efficacies as disinfectants against avian influenza virus (AIV...

  11. CSER 97-004: PFP production denitration calciner system

    Energy Technology Data Exchange (ETDEWEB)

    Hillesland, K.E.

    1997-09-11

    The plutonium stabilization program at the Plutonium Finishing Plant (PFP) includes conversion of acidic plutonium nitrate solution into plutonium oxide. Conversion is facilitated through use of a vertical calciner installed in Glovebox HC-23OC-2, which is located in RM 230C of this facility. This evaluation supports the Criticality Prevention Specification for the calcining process inside this glovebox. As the product of the calciner is a high density plutonium oxide, a number of limits are required to insure criticality safety. The containers allowed are product receiver vessels and 0.5 C slip lid cans and polyjars. The limits allow for two ``unit masses`` of 2 V total volume each, separated by a distance of at least 25.4 cm (10 in.). This evaluation allows for operation of the calciner for product densities not in excess of 5.5 g Pu/cm{sup 3}.

  12. Magnesium Production by Vacuum Aluminothermic Reduction of a Mixture of Calcined Dolomite and Calcined Magnesite

    Science.gov (United States)

    Hu, Wen-xin; Feng, Nai-xiang; Wang, Yao-wu; Wang, Zhi-hui

    A new method of magnesium production was proposed that using a mixture of calcined dolomite and calcined magnesite as raw materials with the molar ratio of MgO to CaO was 6:1 by vacuum aluminothermic reduction. The reduction process was studied by thermodynamic analysis and X-ray diffraction analysis of reduction residue. The reaction of reduction process was CaO+6MgO+4Al=CaO•2Al2O3+6Mg. The effect of briquetting pressure, reduction temperature, time and CaF2 (MgF2) on reduction ratio of MgO was investigated. And the reduction residue that the main phase of CaO•2Al2O3 was leached in alkaline solution for producing sodium aluminateme raw material for special alumina. The results show that the reduction ratio is increased with increasing of the temperature, time, briquetting pressure in range from 40 to 100 MPa and addition of CaF2 or MgF2 in range from 0 to 3%. The alumina leaching ratio of reduction residue reached 88% at the conditions of leaching temperature 95 °C and the concentration ratio of Na2CO3 to NaOH was 100:75 in leaching solution.

  13. Modeling of calcination of single kaolinitic clay particle

    DEFF Research Database (Denmark)

    Gebremariam, Abraham Teklay; Yin, Chungen; Rosendahl, Lasse

    The present work aims at modeling of the calcination (dehydroxylation) process of clay particles, specifically kaolinite, and its thermal transformation. For such purpose, 1D single particle calcination model was developed based on the concept of shrinking core model to assess the dehydroxylation...... distribution within the clay particle and simultaneous density changes due to the reaction kinetics. Accordingly, a particular residence time was noticed as a point where kaolinitic clay particles attain optimum conversion to metakaolinite which is pozzolanic....

  14. CSER 99-001: PFP LAB Dentirating calciner

    Energy Technology Data Exchange (ETDEWEB)

    MILLER, E.M.; DOBBIN, K.D.

    1999-02-22

    A criticality safety evaluation report was prepared for the Plutonium Finishing Plant (PFP) laboratory denigrating calciner, located in Glovebox 188-1, that converts Pu(NO{sub 3}){sub 4} solutions to the high fired stable oxide PuO{sub 2}. Fissile mass limits and volume limits are set for the glovebox for testing operations and training operators using only nitric acid feed to a plutonium oxide bed in the calciner.

  15. Mechanism of boron uptake by hydrocalumite calcined at different temperatures.

    Science.gov (United States)

    Qiu, Xinhong; Sasaki, Keiko; Takaki, Yu; Hirajima, Tsuyoshi; Ideta, Keiko; Miyawaki, Jin

    2015-04-28

    Hydrocalumite (Ca-Al-layered double hydroxide (LDH)) was prepared and applied for the removal of borate. The properties of Ca-Al-LDH calcined at different temperatures were diverse, which affected the sorption density and mechanism of boron species. The sorption density increased with increase in calcined temperature and the sample calcined at 900°C (Ca-Al-LDH-900) showed the maximum sorption density in this work. The solid residues after sorption were characterized by (11)B NMR, (27)Al NMR, SEM, and XRD to investigate the sorption mechanism. Dissolution-reprecipitation was the main mechanism for sorption of borate in Ca-Al-LDH. For Ca-Al-LDH calcined at 300 and 500°C, regeneration occurred in a short time and the newly forming LDHs were decomposed to release Ca(2+) ions and formed ettringite with borate. Two stages occurred in the sorption of boron by Ca-Al-LDH calcined at 900°C. In the first stage, boron species adsorbed on the alumina gel resulting from the hydration of calcined products. In this stage, borate was included as an interlayer anion into the newly forming LDHs in the following stage, and then immobilized as HBO3(2-) into the interlayer, most the LDHs. Copyright © 2015 Elsevier B.V. All rights reserved.

  16. High Temperature Calcination - MACT Upgrade Equipment Pilot Plant Test

    Energy Technology Data Exchange (ETDEWEB)

    Richard D. Boardman; B. H. O& #39; Brien; N. R. Soelberg; S. O. Bates; R. A. Wood; C. St. Michel

    2004-02-01

    About one million gallons of acidic, hazardous, and radioactive sodium-bearing waste are stored in stainless steel tanks at the Idaho Nuclear Technology and Engineering Center (INTEC), which is a major operating facility of the Idaho National Engineering and Environmental Laboratory. Calcination at high-temperature conditions (600 C, with alumina nitrate and calcium nitrate chemical addition to the feed) is one of four options currently being considered by the Department of Energy for treatment of the remaining tank wastes. If calcination is selected for future processing of the sodium-bearing waste, it will be necessary to install new off-gas control equipment in the New Waste Calcining Facility (NWCF) to comply with the Maximum Achievable Control Technology (MACT) standards for hazardous waste combustors and incinerators. This will require, as a minimum, installing a carbon bed to reduce mercury emissions from their current level of up to 7,500 to <45 {micro}g/dscm, and a staged combustor to reduce unburned kerosene fuel in the off-gas discharge to <100 ppm CO and <10 ppm hydrocarbons. The staged combustor will also reduce NOx concentrations of about 35,000 ppm by 90-95%. A pilot-plant calcination test was completed in a newly constructed 15-cm diameter calciner vessel. The pilot-plant facility was equipped with a prototype MACT off-gas control system, including a highly efficient cyclone separator and off-gas quench/venturi scrubber for particulate removal, a staged combustor for unburned hydrocarbon and NOx destruction, and a packed activated carbon bed for mercury removal and residual chloride capture. Pilot-plant testing was performed during a 50-hour system operability test January 14-16, followed by a 100-hour high-temperature calcination pilot-plant calcination run January 19-23. Two flowsheet blends were tested: a 50-hour test with an aluminum-to-alkali metal molar ratio (AAR) of 2.25, and a 50-hour test with an AAR of 1.75. Results of the testing

  17. Calcined Waste Storage at the Idaho Nuclear Technology and Engineering Center

    Energy Technology Data Exchange (ETDEWEB)

    Staiger, M. Daniel, Swenson, Michael C.

    2011-09-01

    This comprehensive report provides definitive volume, mass, and composition (chemical and radioactivity) of calcined waste stored at the Idaho Nuclear Technology and Engineering Center. Calcine composition data are required for regulatory compliance (such as permitting and waste disposal), future treatment of the caline, and shipping the calcine to an off-Site-facility (such as a geologic repository). This report also contains a description of the calcine storage bins. The Calcined Solids Storage Facilities (CSSFs) were designed by different architectural engineering firms and built at different times. Each CSSF has a unique design, reflecting varying design criteria and lessons learned from historical CSSF operation. The varying CSSF design will affect future calcine retrieval processes and equipment. Revision 4 of this report presents refinements and enhancements of calculations concerning the composition, volume, mass, chemical content, and radioactivity of calcined waste produced and stored within the CSSFs. The historical calcine samples are insufficient in number and scope of analysis to fully characterize the entire inventory of calcine in the CSSFs. Sample data exist for all the liquid wastes that were calcined. This report provides calcine composition data based on liquid waste sample analyses, volume of liquid waste calcined, calciner operating data, and CSSF operating data using several large Microsoft Excel (Microsoft 2003) databases and spreadsheets that are collectively called the Historical Processing Model. The calcine composition determined by this method compares favorably with historical calcine sample data.

  18. Total oxidation of toluene over calcined trimetallic hydrotalcites type catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Palacio, Luz A. [Instituto Superior Tecnico, IBB - Centro de Engenharia Biologica e Quimica, Universidade Tecnica de Lisboa, Av. Rovisco Pais, 1049-001 Lisboa (Portugal); Grupo Catalizadores y Adsorbentes, Universidad de Antioquia 1-317, A.A. 1226 Medellin (Colombia); Velasquez, Juliana; Echavarria, Adriana [Grupo Catalizadores y Adsorbentes, Universidad de Antioquia 1-317, A.A. 1226 Medellin (Colombia); Faro, Arnaldo [Departamento de Fisicoquimica, Instituto de Quimica, Universidade Federal do Rio de Janeiro, Ilha do Fundao, CT bloco A, Rio de Janeiro (Brazil); Ramoa Ribeiro, F. [Instituto Superior Tecnico, IBB - Centro de Engenharia Biologica e Quimica, Universidade Tecnica de Lisboa, Av. Rovisco Pais, 1049-001 Lisboa (Portugal); Ribeiro, M. Filipa, E-mail: filipa.ribeiro@ist.utl.pt [Instituto Superior Tecnico, IBB - Centro de Engenharia Biologica e Quimica, Universidade Tecnica de Lisboa, Av. Rovisco Pais, 1049-001 Lisboa (Portugal)

    2010-05-15

    Two trimetallic ZnCuAl and MnCuAl hydrotalcites have been successfully synthesized by a co-precipitation method. The manganese based material was identified as a new hydrotalcite phase. Both lamellar precursors were calcined at 450 and 600 deg. C and the resulting catalysts were tested on reaction of total oxidation of toluene. The solids were characterized by X-ray diffraction, thermal analysis, atomic absorption spectroscopy, Fourier transformed infrared spectroscopy, N{sub 2} adsorption and H{sub 2} temperature-programmed reduction. It was found that ZnCuAl materials are composed of copper and zinc oxides supported on alumina; while MnCuAl ones comprise basically spinel phases, which were not completely identified. The catalytic behavior of the calcined samples showed that Mn hydrotalcite calcined at 450 deg. C exhibited the best catalytic performance that corresponds to 100% toluene conversion into CO{sub 2} at about 300 deg. C.

  19. CSER 95-005: PFP vertical denitration calciner

    Energy Technology Data Exchange (ETDEWEB)

    Geiger, J.L.

    1995-05-31

    The Vertical Denitrating Calciner system will stabilize certain unique solutions containing fissile salts by removing the water and nitrate ion to produce a more easily stored powder. This end is achieved by high-firing the solution in the calciner. The resultant calcine is distinguished by particles which are larger and denser than those produced by the more conventional oxalate precipitation process. This criticality safety evaluation report examines criticality safety for the denitration system, installed in glovebox 188-1 at PFP. The examination shows that, due to the incorporation of standard criticality safety design techniques, the glovebox can be maintained subcritical with minimal reliance on administrative controls. The examination also shows that, ignoring the necessary administrative controls can make a criticality possible in glovebox 188-1. Section 3.0 of this report lists the necessary administrative controls.

  20. Industrial calcination of kaolinitic clays to make reactive pozzolans

    Directory of Open Access Journals (Sweden)

    Roger S. Almenares

    2017-06-01

    Full Text Available This paper presents the results of an industrial trial for the production of calcined clay to be used as pozzolan in cement manufacture. For the trial, a wet-process clinker rotary kiln was modified to process on dry basis the low grade kaolinitic clay used as raw material. The kaolinitic clay deposit was chosen through a screening based on geologic, chemical and mineralogical criteria, and a confirmation of reactivity with an experimental protocol at lab scale. During the calcination trial technological parameters such as rotation speed, fuel pressure and outer temperature of calcined clay were measured and coupled with the reactivity of the samples tested, thus, preliminary estimations of operational parameters can be made. The trial proved that it is possible to produce a reactive pozzolan at industrial scale by implementing small conversions on existing equipment of a typical clinker plant.

  1. Talc-based cementitious products: Effect of talc calcination

    Directory of Open Access Journals (Sweden)

    C.J. Ngally Sabouang

    2015-09-01

    Full Text Available This study reports the use of calcined talc for cementitious products making. The calcination is used to enhance the availability of magnesium from talc to react with phosphate for cement phase formation. It is shown that previous calcination of talc leads to products having enhanced mechanical performance due to the formation of more cement phase than in products based on raw talc. Talc fired at 900 °C was found to be the one in which magnesium release was maximal. Firing at temperature higher than 900 °C leads to the stabilization of enstatite, which decreased the magnesium availability. The cement phase is struvite, which was better detected on the X-ray patterns of the products involving fired talc. All the products have very rapid setting time and low shrinkage.

  2. Apatite formation on calcined kaolin-white Portland cement geopolymer.

    Science.gov (United States)

    Pangdaeng, S; Sata, V; Aguiar, J B; Pacheco-Torgal, F; Chindaprasirt, P

    2015-06-01

    In this study, calcined kaolin-white Portland cement geopolymer was investigated for use as biomaterial. Sodium hydroxide and sodium silicate were used as activators. In vitro test was performed with simulated body fluid (SBF) for bioactivity characterization. The formation of hydroxyapatite bio-layer on the 28-day soaked samples surface was tested using SEM, EDS and XRD analyses. The results showed that the morphology of hydroxyapatite was affected by the source material composition, alkali concentration and curing temperature. The calcined kaolin-white Portland cement geopolymer with relatively high compressive strength could be fabricated for use as biomaterial. The mix with 50% white Portland cement and 50% calcined kaolin had 28-day compressive strength of 59.0MPa and the hydroxyapatite bio-layer on the 28-day soaked sample surface was clearly evident. Copyright © 2015 Elsevier B.V. All rights reserved.

  3. Synthesis of NaY Zeolite Using Mixed Calcined Kaolins

    Directory of Open Access Journals (Sweden)

    Subagjo

    2015-12-01

    Full Text Available Kaolin is one of several types of clay minerals. The most common crystalline phase constituting kaolin minerals is kaolinite, with the chemical composition Al2Si2O5(OH4. Kaolin is mostly used for manufacturing traditional ceramics and also to synthesize zeolites or molecular sieves. The Si-O and Al-O structures in kaolin are inactive and inert, so activation by calcination is required. This work studies the conversion of kaolin originating from Bangka island in Indonesia into calcined kaolin phase as precursor in NaY zeolite synthesis. In the calcination process, the kaolinite undergoes phase transformations from metakaolin to mullite. The Bangka kaolin is 74.3% crystalline, predominantly composed of kaolinite, and 25.7% amorphous, with an SiO2/Al2O3 mass ratio of 1.64. Thermal characterization using simultaneous DSC/TGA identified an endothermic peak at 527°C and an exothermic peak at 1013°C. Thus, three calcination temperatures (700, 1013, and 1050 °C were selected to produce calcined kaolins with different phase distributions. The best product, with 87.8% NaY zeolite in the 54.7% crystalline product and an SiO2/Al2O3 molar ratio of 5.35, was obtained through hydrothermal synthesis using mixed calcined kaolins with a composition of K700C : K1013C : K1050C = 10 : 85 : 5 in %-mass, with seed addition, at a temperature of 93 °Cand a reaction time of 15 hours.

  4. Calcine Waste Storage at the Idaho Nuclear Technology and Engineering Center

    Energy Technology Data Exchange (ETDEWEB)

    M. D. Staiger

    1999-06-01

    A potential option in the program for long-term management of high-level wastes at the Idaho Nuclear Technology and Engineering Center (INTEC), at the Idaho National Engineering and Environmental Laboratory, calls for retrieving calcine waste and converting it to a more stable and less dispersible form. An inventory of calcine produced during the period December 1963 to May 1999 has been prepared based on calciner run, solids storage facilities operating, and miscellaneous operational information, which gives the range of chemical compositions of calcine waste stored at INTEC. Information researched includes calciner startup data, waste solution analyses and volumes calcined, calciner operating schedules, solids storage bin capacities, calcine storage bin distributor systems, and solids storage bin design and temperature monitoring records. Unique information on calcine solids storage facilities design of potential interest to remote retrieval operators is given.

  5. Modeling the Gas-Solid Flow in Calcining Furnace

    Directory of Open Access Journals (Sweden)

    Haiyan Luo

    2011-03-01

    Full Text Available Gas-solid two-phase flow in calcining furnace is investigated in this paper. The turbulent fluid phase is calculated using the RNG k-e two-equation model in the Eulerain framework while the solid phase being handled via the particle stochastic trajectory model is calculated in the Lagrangian framework. Flow pattern characteristics of the fluid phase and the particle trajectories of the solid phase were predicted subject to a range of flow conditions and different particle sizes. The computed results provided useful information in the preview of kinetics regulation of the gas-solid two-phase in calcining furnace.

  6. Predicting the Wear of High Friction Surfacing Aggregate

    Directory of Open Access Journals (Sweden)

    David Woodward

    2017-05-01

    Full Text Available High friction surfacing (HFS is a specialist type of road coating with very high skid resistance. It is used in the UK at locations where there is significant risk of serious or fatal accidents. This paper considers the aggregate used in HFS. Calcined bauxite is the only aggregate that provides the highest levels of skid resistance over the longest period. No naturally occurring aggregate has been found to give a comparable level of in-service performance. This paper reviews the historical development of HFS in the UK relating to aggregate. In-service performance is predicted in the laboratory using the Wear test which subjects test specimens to an estimated 5–8 years simulated trafficking. Examples are given of Wear test data. They illustrate why calcined bauxite performs better than natural aggregate. They show how the amount of calcined bauxite can be reduced by blending with high skid resistant natural aggregates. Data from the Wear test can be related to every HFS laboratory experiment and road trial carried out in the UK for over the last 50 years. Anyone considering the prediction of HFS performance needs to carefully consider the data given in this paper with any other test method currently being considered or used to investigate HFS.

  7. Process Design Concepts for Stabilization of High Level Waste Calcine

    Energy Technology Data Exchange (ETDEWEB)

    T. R. Thomas; A. K. Herbst

    2005-06-01

    The current baseline assumption is that packaging ¡§as is¡¨ and direct disposal of high level waste (HLW) calcine in a Monitored Geologic Repository will be allowed. The fall back position is to develop a stabilized waste form for the HLW calcine, that will meet repository waste acceptance criteria currently in place, in case regulatory initiatives are unsuccessful. A decision between direct disposal or a stabilization alternative is anticipated by June 2006. The purposes of this Engineering Design File (EDF) are to provide a pre-conceptual design on three low temperature processes under development for stabilization of high level waste calcine (i.e., the grout, hydroceramic grout, and iron phosphate ceramic processes) and to support a down selection among the three candidates. The key assumptions for the pre-conceptual design assessment are that a) a waste treatment plant would operate over eight years for 200 days a year, b) a design processing rate of 3.67 m3/day or 4670 kg/day of HLW calcine would be needed, and c) the performance of waste form would remove the HLW calcine from the hazardous waste category, and d) the waste form loadings would range from about 21-25 wt% calcine. The conclusions of this EDF study are that: (a) To date, the grout formulation appears to be the best candidate stabilizer among the three being tested for HLW calcine and appears to be the easiest to mix, pour, and cure. (b) Only minor differences would exist between the process steps of the grout and hydroceramic grout stabilization processes. If temperature control of the mixer at about 80„aC is required, it would add a major level of complexity to the iron phosphate stabilization process. (c) It is too early in the development program to determine which stabilizer will produce the minimum amount of stabilized waste form for the entire HLW inventory, but the volume is assumed to be within the range of 12,250 to 14,470 m3. (d) The stacked vessel height of the hot process vessels

  8. Calcined eggshell (CES): An efficient natural catalyst for ...

    Indian Academy of Sciences (India)

    A convenient, eco-friendly and economic method for Knoevenagel condensation of aromatic aldehydes with active methylene compounds using calcined eggshell (CES) as an efficient natural catalyst in aqueous medium has been reported. CES is a new, ecologically safe and inexpensive green catalyst obtained from ...

  9. Utilization of Microwave Energy in the Calcination and ...

    African Journals Online (AJOL)

    The application of microwave energy in the calcination and agglomeration of manganese carbonate ore from Nsuta, Ghana, has been investigated. The real and imaginary permittivities, which may be used to determine a substance's response to microwave heating, were measured and the permittivities of both the ore and ...

  10. Kinetic Study of Calcination of Jakura Limestone Using Power Rate ...

    African Journals Online (AJOL)

    The current demand of hydrated lime [Ca(OH)2] worldwide has necessitated investigation into kinetics of calcinations of some large commercial deposits of limestone in Nigeria. The study is aimed at finding kinetic parameters for the purpose of energy saving, lime kiln design, modeling and simulation of lime kiln.

  11. Effect of Calcination and Reduction Temperatures on the Reduction ...

    African Journals Online (AJOL)

    The effect of calcination and reduction temperatures on the reducibility, dispersion and Fischer-Tropsch activity of 10 wt% cobalt supported on titania catalyst modified by 0.1 wt% boron has been studied. The percentage reduction and ... The reduction temperature did not affect the product selectivity. South African Journal of ...

  12. Screening Level Risk Assessment for the New Waste Calcining Facility

    Energy Technology Data Exchange (ETDEWEB)

    M. L. Abbott; K. N. Keck; R. E. Schindler; R. L. VanHorn; N. L. Hampton; M. B. Heiser

    1999-05-01

    This screening level risk assessment evaluates potential adverse human health and ecological impacts resulting from continued operations of the calciner at the New Waste Calcining Facility (NWCF) at the Idaho Nuclear Technology and Engineering Center (INTEC), Idaho National Engineering and Environmental Laboratory (INEEL). The assessment was conducted in accordance with the Environmental Protection Agency (EPA) report, Guidance for Performing Screening Level Risk Analyses at Combustion Facilities Burning Hazardous Waste. This screening guidance is intended to give a conservative estimate of the potential risks to determine whether a more refined assessment is warranted. The NWCF uses a fluidized-bed combustor to solidify (calcine) liquid radioactive mixed waste from the INTEC Tank Farm facility. Calciner off volatilized metal species, trace organic compounds, and low-levels of radionuclides. Conservative stack emission rates were calculated based on maximum waste solution feed samples, conservative assumptions for off gas partitioning of metals and organics, stack gas sampling for mercury, and conservative measurements of contaminant removal (decontamination factors) in the off gas treatment system. Stack emissions were modeled using the ISC3 air dispersion model to predict maximum particulate and vapor air concentrations and ground deposition rates. Results demonstrate that NWCF emissions calculated from best-available process knowledge would result in maximum onsite and offsite health and ecological impacts that are less then EPA-established criteria for operation of a combustion facility.

  13. Effect of Calcination and Reduction Temperatures on the Reduction ...

    African Journals Online (AJOL)

    2003-12-05

    Dec 5, 2003 ... The effect of calcination and reduction temperatures on the reducibility, dispersion and Fischer-Tropsch activity of 10 wt% cobalt supported on titania catalyst modified by 0.1 wt% boron has been studied. The percentage reduction and percentage dispersion were found to decrease with increasing ...

  14. Mechanical and electrical properties of calcinated tea-based cellulose composite films

    Science.gov (United States)

    Tippabattini, Jayaramudu; Kim, Jung Woong; Ko, Hyun-U.; Kafy, Abdullahil; Li, Yaguang; Kim, Jaehwan

    2017-04-01

    In the present investigation, calcinated tea-based cellulose composite films were fabricated via solution casting technique. The fabricated films were characterized by using Fourier transform infrared spectroscopy and differential scanning calorimetry. The effect of calcinated tea loading on the properties of the calcinated tea-based cellulose composite films was studied. The results were showed that the calcinated tea composite films display better mechanical properties and dielectric constant than the pure cellulose films.

  15. Calcined Waste Storage at the Idaho Nuclear Technology and Engineering Center

    Energy Technology Data Exchange (ETDEWEB)

    M. D. Staiger

    2007-06-01

    This report provides a quantitative inventory and composition (chemical and radioactivity) of calcined waste stored at the Idaho Nuclear Technology and Engineering Center. From December 1963 through May 2000, liquid radioactive wastes generated by spent nuclear fuel reprocessing were converted into a solid, granular form called calcine. This report also contains a description of the calcine storage bins.

  16. The Kinetic Model of Calcination and Carbonation of Anadara Granosa

    OpenAIRE

    Rashidi, Nor Adilla; Mohamed, Mustakimah; Yusup, Suzana

    2016-01-01

    Utilization of calcium-based adsorbent in carbon dioxide (CO2) separation from the gas stream through the calcination and carbonation process is extensively applied in the gas purification process, especially at the elevated reaction temperature. Typically, natural calcium carbonates (CaCO3) such as the limestone, magnesite and dolomite are widely consumed in the process due to their low cost and large abundance of these materials. However, in this research study, the potential of waste cockl...

  17. Mathematical modeling of an in-line low-NOx calciner

    DEFF Research Database (Denmark)

    Iliuta, Ion; Dam-Johansen, Kim; Jensen, Lars Skaarup

    2002-01-01

    The reduction of the NOx content in in-line-calciner-type kiln systems can be made by optimization of the primary filing in the rotary kiln and of the secondary firing in the calciner. Because the optimization of calciner offers greater opportunities the mathematical modeling of this reactor...... is very important. A heterogeneous, dynamic mathematical model for an in-line low-NOx calciner based on non-isothermal diffusion reaction models for char combustion and limestone calcination has been developed. The importance of the rate at which preheated combustion air was mixed into the main flow...

  18. The influence of calcination on the physical and chemical properties of petroleum and mixed cokes

    Energy Technology Data Exchange (ETDEWEB)

    Sikora, K.; Syrek, H.

    1980-01-01

    Freshly prepared petroleum and coal-petroleum cokes, before utilization for the production of various materials, are subjected to calcining--thermal treatment in a neutral or reducing atmosphere without the admission of air at less than or equal to 1400/sup 0/. During calcining, stabilization of the physical and chemical properties of the cokes takes place. The properties of the obtained coke depend chiefly on the calcining time and temperature. During calcining, volatile substances are removed almost completely from the coke; the coke density is increased, and its structure is put in order; the electrical conductivity is improved; the mechanical strength is increased; and the reactivity of the coke is decreased. Laboratory studies were conducted on calcining mixed coal-petroleum cokes of two grades at 1200, 1250, and 1300/sup 0/ for 2-6 h. In the calcining products the content of volatile substances, the ash content, S content, and density were determined. It was ascertained that calcining of mixed coal-petroleum cokes goes analogously to calcining of pure petroleum cokes. Raising the temperature and increasing the time of calcining has a substantial effect on improvement of coke physical and chemical properties. For high-quality coke, calcining is to be carried out at greater than or equal to 1300/sup 0/ for 4-6 h, for ordinary coke at > 1200/sup 0/ and greater than or equal to 4 h. The results are regarded as starting data for an industrial study of the calcining process.

  19. Experimental Results of NWCF Run H4 Calcine Dissolution Studies Performed in FY-98 and -99

    Energy Technology Data Exchange (ETDEWEB)

    Garn, Troy Gerry; Herbst, Ronald Scott; Batcheller, Thomas Aquinas; Sierra, Tracy Laureena

    2001-08-01

    Dissolution experiments were performed on actual samples of NWCF Run H-4 radioactive calcine in fiscal years 1998 and 1999. Run H-4 is an aluminum/sodium blend calcine. Typical dissolution data indicates that between 90-95 wt% of H-4 calcine can be dissolved using 1gram of calcine per 10 mLs of 5-8M nitric acid at boiling temperature. Two liquid raffinate solutions composed of a WM-188/aluminum nitrate blend and a WM-185/aluminum nitrate blend were converted into calcine at the NWCF. Calcine made from each blend was collected and transferred to RAL for dissolution studies. The WM-188/aluminum nitrate blend calcine was dissolved with resultant solutions used as feed material for separation treatment experimentation. The WM-185/aluminum nitrate blend calcine dissolution testing was performed to determine compositional analyses of the dissolved solution and generate UDS for solid/liquid separation experiments. Analytical fusion techniques were then used to determine compositions of the solid calcine and UDS from dissolution. The results from each of these analyses were used to calculate elemental material balances around the dissolution process, validating the experimental data. This report contains all experimental data from dissolution experiments performed using both calcine blends.

  20. Microstructural changes in porous hematite nanoparticles upon calcination

    DEFF Research Database (Denmark)

    Johnsen, Rune; Knudsen, Kenneth D.; Molenbroek, Alfons M.

    2011-01-01

    This combined study using small-angle neutron scattering (SANS), X-ray powder diffraction (XRPD), transmission electron microscopy (TEM) and adsorption isotherm techniques demonstrates radical changes in the microstructure of porous hematite (-Fe2O3) nanoparticles upon calcination in air. TEM...... images of the as-synthesized hematite sample show that it consists of subrounded nanoparticles [50 (8)–61 (11) nm in average minimum and maximum diameters] with an apparent porous structure of nanosized pores/ channels or cracks. SANS data confirm the presence of two characteristic sizes, one originating...

  1. KINETICS OF SORPTION OF FLUORIDE ON CALCINED MAGNESITE IN BATCH

    DEFF Research Database (Denmark)

    Singano, J. J.; Mashauri, D. A.; Mtalo, F. W.

    1997-01-01

    on first-order reaction with respect to the concentration of fluoride. The rate constant is directly proportional to the dosage. The model takes into accounts the lag time observed. The kinetical model can be described for any given dosage and initial fluoride concentration in the water. The reaction rate...... parameter, K, varies however slightly for different initial concentrations of fluoride in the water and different dosage of calcined magnesia. These relationships are described separately by two linear equations. It is discussed that the observed lag time is due to the fact that magnesia cannot remove...

  2. Influence of roasting-quenching pretreatment on the rice husk silica prepared by calcination method

    Science.gov (United States)

    Maksum, Ahmad; Rustandi, Andi; Permana, Sulaksana; Soedarsono, Johny Wahyuadi

    2017-03-01

    Calcination is a simple method to produce silica from rice husk (RH). One of the key to obtain higher purity silica from rice husk by calcination method is the effectiveness of impurities removal, especially potassium, from RH surface before calcination process. So, in the present study, an attempt has been made to produce high purity silica powder by using calcination method with the combination of roasting-quenching and acid leaching as a pretreatment to eliminate metal impurities, especially potassium, detected by using inductively coupled plasma mass spectrometry (ICP-MS). Finally, the high purity silica, 99.928% was obtained by roasting and calcination temperature of 300°C and 650°C, respectively. However, by considering less energy usage and silica purity achievement, the combination of 300°C roasting-quenching, 1M hydrochloric acid leaching, and calcination at the temperature of 600°C was the best route.

  3. Effect of calcination methods on electrochemical performance of NiO ...

    Indian Academy of Sciences (India)

    Ni(OH)2 precursors were prepared via the precipitation transformation method, which was originated from Na2C2O4, NiSO4.6H2O and urea. NiO samples were successfully obtained by calcining Ni(OH)2 precursor with different calcination methods. Some were calcination in a tube furnace under the nitrogen flow and ...

  4. Cyclic Carbonation Calcination Studies of Limestone and Dolomite for CO2 Separation From Combustion Flue Gases

    OpenAIRE

    Sivalingam, S.;Gleis, S.;Hartmut, S.;Yrjas, P.;Hupa, M.

    2017-01-01

    Naturally occurring limestone and dolomite samples, originating from different geographical locations, were tested as potential sorbents for carbonation/calcination based CO2 capture from combustion flue gases. Samples have been studied in a thermogravimetric analyzer under simulated flue gas conditions at three calcination temperatures,viz., 750textdegreeC, 875textdegreeC, and 930textdegreeC for four carbonation calcination reaction (CCR) cycles. The dolomite sample exhibited the highest rat...

  5. In vitro studies evaluating leaching of mercury from mine waste calcine using simulated human body fluids

    Science.gov (United States)

    Gray, John E.; Plumlee, Geoffrey S.; Morman, Suzette A.; Higueras, Pablo L.; Crock, James G.; Lowers, Heather A.; Witten, Mark L.

    2010-01-01

    In vitro bioaccessibility (IVBA) studies were carried out on samples of mercury (Hg) mine-waste calcine (roasted Hg ore) by leaching with simulated human body fluids. The objective was to estimate potential human exposure to Hg due to inhalation of airborne calcine particulates and hand-to-mouth ingestion of Hg-bearing calcines. Mine waste calcines collected from Hg mines at Almadén, Spain, and Terlingua, Texas, contain Hg sulfide, elemental Hg, and soluble Hg compounds, which constitute primary ore or compounds formed during Hg retorting. Elevated leachate Hg concentrations were found during calcine leaching using a simulated gastric fluid (as much as 6200 μg of Hg leached/g sample). Elevated Hg concentrations were also found in calcine leachates using a simulated lung fluid (as much as 9200 μg of Hg leached/g), serum-based fluid (as much as 1600 μg of Hg leached/g), and water of pH 5 (as much as 880 μg of Hg leached/g). The leaching capacity of Hg is controlled by calcine mineralogy; thus, calcines containing soluble Hg compounds contain higher leachate Hg concentrations. Results indicate that ingestion or inhalation of Hg mine-waste calcine may lead to increased Hg concentrations in the human body, especially through the ingestion pathway.

  6. Feasibility of Carbonaceous Nanomaterial-Assisted Photocatalysts Calcined at Different Temperatures for Indoor Air Applications

    Directory of Open Access Journals (Sweden)

    Wan-Kuen Jo

    2012-01-01

    Full Text Available This study examined the characteristics and photocatalytic activity of multiwall carbon nanotube-assisted TiO2 (MWNT-TiO2 nanocomposites calcined at different temperatures to assess their potential indoor air applications. It was confirmed that the composites calcined at low temperatures (300 and 400°C contained TiO2 nanoparticles bound intimately to the MWNT networks. Meanwhile, almost no MWNTs were observed when the calcination temperature was increased to 500 and 600°C. The MWNT-TiO2 composites calcined at low temperatures showed higher photocatalytic decomposition efficiencies for aromatic hydrocarbons at indoor concentrations than those calcined at high temperatures. The mean efficiencies for benzene, toluene, ethyl benzene, and o-xylene (BTEX by the composite calcined at 300°C were 32, 70, 79, and 79%, respectively, whereas they were 33, 71, 78, and 78% for the composite calcined at 400°C, respectively. In contrast, the efficiencies decreased to close to zero when the calcination temperature was increased to 600°C. Moreover, the MWNT-TiO2 exhibited superior photocatalytic performance for the decomposition efficiencies compared to TiO2 under conventional UV-lamp irradiations. Consequently, these carbonaceous nanomaterial-assisted photocatalysts can be applied effectively to indoor air applications depending upon the calcination temperature.

  7. Calcined iron rich clay as an adsorbent and a photocatalyst for the ...

    African Journals Online (AJOL)

    Calcined iron rich clay as an adsorbent and a photocatalyst for the degradation of phenol. ... Nigerian Journal of Technological Research ... This study investigates the potential of a calcined iron rich clay for the removal of phenol from aqueous solutions (adsorption) and subsequent degradation of the adsorbed phenol ...

  8. Test Plan for Radioactive Testing of a Vertical Direct Denitration Calciner

    Energy Technology Data Exchange (ETDEWEB)

    COMPTON, J.A.

    1999-10-05

    A vertical calciner will be used to demonstrate the direct denitration process for converting plutonium-bearing liquors to stable plutonium rich solids. The calciner and some of its associated equipment were previously tested with non-radioactive chemicals to demonstrate operability.

  9. Calcination effects on CeZrOx geometry and styrene production from ethylbenzene

    NARCIS (Netherlands)

    Kovacevic, M.; Brunet Espinosa, Roger; Lefferts, Leonardus; Mojet, Barbara

    2014-01-01

    A series of CeZrOx catalysts was prepared by calcination of hydrothermally obtained metal oxide precipitate at increasing temperatures. The samples were characterized by HRSEM, XRD and Raman spectroscopy, showing a change in morphology and particle size as a function of calcination temperature.

  10. Model for the sulfidation of calcined limestone and its use in reactor models.

    NARCIS (Netherlands)

    Heesink, Albertus B.M.; Brilman, Derk Willem Frederik; van Swaaij, Willibrordus Petrus Maria

    1998-01-01

    A mathematical model describing the sulfidation of a single calcined limestone particle was developed and experimentally verified. This model, which includes no fitting parameters, assumes a calcined limestone particle to consist of spherical grains of various sizes that react with H2S according to

  11. LITERATURE REVIEW OF PUO2 CALCINATION TIME AND TEMPERATURE DATA FOR SPECIFIC SURFACE AREA

    Energy Technology Data Exchange (ETDEWEB)

    Daniel, G.

    2012-03-06

    The literature has been reviewed in December 2011 for calcination data of plutonium oxide (PuO{sub 2}) from plutonium oxalate Pu(C{sub 2}O{sub 4}){sub 2} precipitation with respect to the PuO{sub 2} specific surface area (SSA). A summary of the literature is presented for what are believed to be the dominant factors influencing SSA, the calcination temperature and time. The PuO{sub 2} from Pu(C{sub 2}O{sub 4}){sub 2} calcination data from this review has been regressed to better understand the influence of calcination temperature and time on SSA. Based on this literature review data set, calcination temperature has a bigger impact on SSA versus time. However, there is still some variance in this data set that may be reflecting differences in the plutonium oxalate preparation or different calcination techniques. It is evident from this review that additional calcination temperature and time data for PuO{sub 2} from Pu(C{sub 2}O{sub 4}){sub 2} needs to be collected and evaluated to better define the relationship. The existing data set has a lot of calcination times that are about 2 hours and therefore may be underestimating the impact of heating time on SSA. SRNL recommends that more calcination temperature and time data for PuO{sub 2} from Pu(C{sub 2}O{sub 4}){sub 2} be collected and this literature review data set be augmented to better refine the relationship between PuO{sub 2} SSA and its calcination parameters.

  12. Calcination effect of borate-bearing hydroxyapatite on the mobility of borate.

    Science.gov (United States)

    Sasaki, Keiko; Toshiyuki, Kenta; Guo, Binglin; Ideta, Keiko; Hayashi, Yoshikazu; Hirajima, Tsuyoshi; Miyawaki, Jin

    2018-02-15

    Discharge from accidental nuclear power plants includes boric acid, which is used as a neutron absorbent in nuclear reactors. Co-precipitation of borate with hydroxyapatite (HAp), using Ca(OH) 2 , is known to be an effectively fast method for stabilization of borate as well as coexisting radioactive nuclides. To reduce bulky volume of solid residues after co-precipitation, calcination is necessary to investigate the chemical stability of targets. Calcination at 850°C resulted in the high crystalization of HAp with formation of xCaO·B 2 O 3 as a by-phase in which x increased with a decrease in the borate contents. After calcination, the lattice parameter a of HAp showed a reentrant curve and c showed a convex curve with an increase in borate contents. A dissolution assay revealed that calcination sometimes increases the borate moiety and that the acceptable B contents in HAp are lower than 1.59mmol/g-calcined HAp. These results imply that during calcination of HAp, some borate is excluded to form the by-phase xCaO·B 2 O 3 , which is relatively insoluble in water, but some other fractions might be additionally emitted from the amorphous phase to weakly bind the calcined products. Copyright © 2017 Elsevier B.V. All rights reserved.

  13. Enhanced photocatalytic activity of calcined natural sphalerite under visible light irradiation

    Directory of Open Access Journals (Sweden)

    Abdulhamid Hamza

    2017-01-01

    Full Text Available The photocatalytic activity of natural sphalerite (the main mineral ore of ZnS is relatively low in the absence of sacrificial donors. Present work focuses on the improvement of the photocatalytic activity of a natural sphalerite obtained from Abuni deposit, Nigeria, via calcination at 600 °C, 700 °C and 800 °C. The raw and calcined natural sphalerite samples were characterized using X-ray diffraction (XRD, scanning electron microscopy (SEM, and specific surface area analysis. The activity of the raw and calcined samples was evaluated using photocatalytic decolorization of methyl orange (MO as the model reaction. The kinetics of photocatalytic decolorization of MO on the raw and calcined natural sphalerite samples was fitted to the pseudo-first order approximation of the Langmuir–Hinshelwood model. The photocatalytic activity of the natural sphalerite was doubled upon calcination at 700 °C. The natural sphalerite calcined at 700 °C is also more active than the ones calcined at 600 °C and 800 °C due to the combined effects of chemical composition, crystallite size, specific surface area and oxygen vacancies.

  14. Stop Smoking—Tube-In-Tube Helical System for Flameless Calcination of Minerals

    Directory of Open Access Journals (Sweden)

    Nils Haneklaus

    2017-11-01

    Full Text Available Mineral calcination worldwide accounts for some 5–10% of all anthropogenic carbon dioxide (CO2 emissions per year. Roughly half of the CO2 released results from burning fossil fuels for heat generation, while the other half is a product of the calcination reaction itself. Traditionally, the fuel combustion process and the calcination reaction take place together to enhance heat transfer. Systems have been proposed that separate fuel combustion and calcination to allow for the sequestration of pure CO2 from the calcination reaction for later storage/use and capture of the combustion gases. This work presents a new tube-in-tube helical system for the calcination of minerals that can use different heat transfer fluids (HTFs, employed or foreseen in concentrated solar power (CSP plants. The system is labeled ‘flameless’ since the HTF can be heated by other means than burning fossil fuels. If CSP or high-temperature nuclear reactors are used, direct CO2 emissions can be divided in half. The technical feasibility of the system has been accessed with a brief parametric study here. The results suggest that the introduced system is technically feasible given the parameters (total heat transfer coefficients, mass- and volume flows, outer tube friction factors, and –Nusselt numbers that are examined. Further experimental work will be required to better understand the performance of the tube-in-tube helical system for the flameless calcination of minerals.

  15. The effect of calcination conditions on the graphitizability of novel synthetic and coal-derived cokes

    Science.gov (United States)

    Bennett, Barbara Ellen

    The effects of calcination heating rate and ultimate calcination temperature upon calcined coke and subsequent graphitic material microstructures were studied for materials prepared from three different precursors. The pitch precursors used were Mitsubishi AR pitch (a synthetic, 100% mesophase pitch), the NMP-extracted portion of a raw coal, and the NMP-extracted fraction of a coal liquefaction residue obtained from an HTI pilot plant. These materials were all green-coked under identical conditions. Optical microscopy confirmed that the Mitsubishi coke was very anisotropic and the HTI coke was nearly as anisotropic. The coke produced from the direct coal extract was very isotropic. Crystalline development during calcination heating was verified by high-temperature x-ray diffraction. Experiments were performed to ascertain the effects of varying calcination heating rate and ultimate temperature. It was determined that calcined coke crystallite size increased with increasing temperature for all three materials but was found to be independent of heating rate. The graphene interplanar spacing decreased with increasing temperature for the isotropic NMP-extract material but increased with increasing temperature for the anisotropic materials---Mitsubishi and HTI cokes. Graphene interplanar spacing was also found to be independent of heating rate. Calcined coke real densities were, likewise, found to be independent of heating rate. The anisotropic cokes (Mitsubishi and HTI) exhibited increasing real density with increasing calcination temperature. The NMP-extract coke increased in density up to 1050°C and then suffered a dramatic reduction in real density when heated to 1250°C. This is indicative of puffing. Since there was no corresponding disruption in the crystalline structure, the puffing phenomena was determined to be intercrystalline rather than intracrystalline. After the calcined cokes were graphitized (under identical conditions), the microstructures were re

  16. SYNTHESIS OF SnO2 NANOCRYSTALS BY SOLID STATE REACTION FOLLOWED BY CALCINATION

    Institute of Scientific and Technical Information of China (English)

    Shanmin Gao; Li Pang; Hongwei Che; Xiaoping Zhou

    2004-01-01

    Nanocrystalline SnO2 was synthesized by direct mixing and grinding of SnCl4·5H2O and NaOH at roomtemperature, followed by calcination at different temperatures for different times in air. Product samples were characterized by X-ray diffraction and transmission electron microscope, revealing that the amorphous precursor SnO2 was transformed to crystals at 200 ℃ for 3 h, and that the average particle size increased upon raising the calcining temperature or prolonging the calcining time. The mechanism of the phase transformation of the products is discussed.

  17. SCALE FOR CONSTRUCTIVE AGGREGATION

    OpenAIRE

    Sujitha Mary; Alaguraj, V.; Krishnaswamy, S

    2014-01-01

    Aggregation is an inherent property of proteins. Both ordered and disordered proteins have a tendency to aggregate. Protein folding itself starts from the partially folded intermediates. The formation of native structures from these intermediates may be called as constructive aggregation. We describe the design of an intrinsic aggregation scale and its efficiency in finding hot-spots for constructive aggregation. In this paper, we are proposing a new aspect of aggregation, wherein...

  18. Heat Transfer Characteristics of Calcined Petroleum Coke in Waste Heat Recovery Process

    Directory of Open Access Journals (Sweden)

    Bin Zheng

    2016-01-01

    Full Text Available This paper reports the results of heat transfer characteristics of calcined petroleum coke in waste heat recovery process. The model of heat exchanger was set up. The model has been used to investigate the effects of porosity (0.58 to 0.79, equivalent heat conductivity coefficient (0.9 to 1.1, and equivalent specific heat (0.9 to 1.1. The calculated values of calcined petroleum coke temperature showed good agreement with the corresponding available experimental data. The temperature distribution of calcined petroleum coke, the calcined petroleum coke temperature at heat exchanger outlet, the average heat transfer coefficient, and the heat recovery efficiency were studied. It can also be used in deriving much needed data for heat exchanger designs when employed in industry.

  19. Calcined eggshell as a cost effective material for removal of dyes from aqueous solution

    Science.gov (United States)

    Borhade, A. V.; Kale, A. S.

    2017-04-01

    The removal of Rhodamine B, Eriochrome black T and Murexide dyes from aqueous solutions using calcined eggshell powder were investigated. In this study, calcined eggshell powder was applied for its potential use as an adsorbent for the removal of Rhodamine B, Eriochrome black T and Murexide dyes from their aqueous solutions. The calcined eggshell powder obtained was characterized by Fourier Transform Infrared Spectroscopy (FT-IR), Thermogravimetric Analysis (TGA), Scanning Electron Microscopy (SEM) and X-ray Diffraction (XRD). The various parameters such as initial concentration, pH, adsorbent dose and contact time were studied. Various isotherms including Langmuir, Freundlich, Temkin and Dubinin-Radushkevich isotherm models were applied for the equilibrium adsorption data. The kinetic study of Rhodamine B, Eriochrome black T and Murexide dyes on calcined eggshell powder follows pseudo-second order kinetics.

  20. Test Plan for Radioactive Testing of a Vertical Direct Denitration Calciner

    Energy Technology Data Exchange (ETDEWEB)

    COMPTON, J.A.

    2000-02-03

    Stored solutions containing plutonium and nitric acid and possibly uranium thorium and minor amounts of other substances will be used for development and demonstration of a vertical calciner direct denitration process for conversion of those to stable storable PuO{sub 2} rich solids. Some of those solutions are quite dilute and very impure these require either pretreatment to make them suitable for calciner feed or an alternate stabilization method. Untreated scrap solutions containing some amounts of sulfate phosphate sodium and/or potassium may also be tested for suitability of direct denitration for conversion directly to PuO{sub 2}-rich solids. A vertical calciner will be used to demonstrate the direct denitration process for converting plutonium-bearing liquors to stable plutonium rich solids. The calciner and some of its associated equipment were previously tested with non-radioactive chemicals to demonstrate operability.

  1. CFD Modelling and Experimental Testing of Thermal Calcination of Kaolinite Rich Clay Particles - An Effort towards Green Concrete

    DEFF Research Database (Denmark)

    Gebremariam, Abraham Teklay

    at inappropriately high temperatures or long retention time will not only waste energy but also decrease the reactivity of the calcines due to possible recrystallization of the reactive phase into a stable crystalline phase. Therefore, it is very crucial to achieve an in-depth understanding of the calcination...... processes in a calciner and develop a useful tool that can aid in design of a smart clay calcination technology, which makes the major objective of this study. In this thesis, a numerical approach is mainly used to investigate the flash calcination of clay particles. A transient one-dimensional particle...... model which fully addresses not only the particle-ambient flow interaction but also the intra-particle processes has been successfully developed in a C++ program to examine calcination of clay particles suspended in a hot gas. The calcination process is also numerically studied using gPROMS (a general...

  2. Spectral-Luminescence Characteristics of Laser Dyes in a Calcined Xerogel

    Science.gov (United States)

    Bezkrovnaya, O. N.; Maslov, V. V.; Pritula, I. M.; Yurkevych, A. G.; Chayka, M. A.; Gurkalenko, Yu. A.; Pereverzev, N. V.

    2017-03-01

    Spectral and luminescence characteristics of three laser dyes incorporated into xerogel matrices preliminarily calcined under 700oC were studied in the spectral range of 600-700 nm. A stabilizing effect of these matrices on the dye molecules in the S1 exited state was revealed. This effect manifested in decreasing nonradiative losses in this state and increasing the quantum yield of the dye luminescence in a calcined xerogel as compared with methanol.

  3. Étude de la calcination du phosphate clair de youssoufia (Maroc ...

    African Journals Online (AJOL)

    AKA Boko

    refroidissement. Mots-clés : Phosphate, matière organique, calcination, Youssoufia, Maroc. Abstract ... Moreover, we note that the granulometric distribution of calcined phosphates varies according to the rate of its .... 50,079 ; 20,885), et les carbonates qui sont sous forme de la dolomite CaMg(CO3)2 (2θ : 30,917 ; 50,674 ...

  4. Formulation Efforts for Direct Vitrification of INEEL Blend Calcine Waste Simulate: Fiscal Year 2000

    Energy Technology Data Exchange (ETDEWEB)

    Crum, Jarrod V.; Vienna, John D.; Peeler, David K.; Reamer, I. A.

    2001-03-30

    This report documents the results of glass formulation efforts for Idaho National Engineering and Environmental Laboratory (INEEL) high level waste (HWL) calcine. Two waste compositions were used during testing. Testing started by using the Run 78 calcine composition and switched to simulated Blend calcine composition when it became available. The goal of the glass formulation efforts was to develop a frit composition that will accept higher waste loading that satisfies the glass processing and product acceptance constraints. 1. Melting temperature of 1125 ? 25?C 2. Viscosity between 2 and 10 Pa?s at the melting temperature 3. Liquidus temperature at least 100?C below the melting temperature 4. Normalized release of B, Li and Na each below 1 g/m2 (per ASTM C 1285-97) Glass formulation efforts tested several frit compositions with variable waste loadings of Run 78 calcine waste simulant. Frit 107 was selected as the primary candidate for processing since it met all process and performance criteria up to 45 mass% waste loading. When the simulated Blend calcine waste composition became available Frits 107 and 108 compositions were retested and again Frit 107 remained the primary candidate. However, both frits suffered a decrease in waste loading when switching from the Run 78 calcine to simulated Blend calcine waste composition. This was due to increase concentrations of both F and Al2O3 along with a decrease in CaO and Na2O in the simulate Blend calcine waste all of which have strong impacts on the glass properties that limit waste loading of this type of waste.

  5. Sorption characteristics of fluoride on to magnesium oxide-rich phases calcined at different temperatures.

    Science.gov (United States)

    Sasaki, Keiko; Fukumoto, Naoyuki; Moriyama, Sayo; Hirajima, Tsuyoshi

    2011-07-15

    The effect of calcination temperature during production of magnesium oxide-rich phases from MgCO(3) on the sorption of F(-) ions in the aqueous phase has been investigated. Magnesium oxide-rich phases were formed by calcination at over 873 K for 1h. Higher calcination temperatures produced more crystalline MgO with smaller specific surface area and provided larger values of the total basicity per unit surface area. The higher calcination temperatures lead to slower F(-) removal rate, and lower equilibrium F(-) concentrations, when the equilibrium F(-) concentrations are less than 1 mmol dm(-3). Larger total basicity per unit surface area made the reactivity with F(-) ions in aqueous phase more feasible, resulting in a greater degree of F(-) sorption. For equilibrium F(-) concentrations more than 1 mmol dm(-3), lower calcination temperatures favored the co-precipitation of F(-) with Mg(OH)(2), probably leading to the formation of Mg(OH)(2-x)F(x), and the achievement of larger sorption density. This is the first paper which describes the relationship between the solid base characteristics obtained by CO(2)-TPD for MgO with different calcination temperatures as a function of the reactivity of F(-) sorption in the aqueous phase. Copyright © 2011 Elsevier B.V. All rights reserved.

  6. Carbon dioxide absorption and release properties of pyrolysis products of dolomite calcined in vacuum atmosphere.

    Science.gov (United States)

    Wang, Fei; Kuzuya, Toshihiro; Hirai, Shinji; Li, Jihua; Li, Te

    2014-01-01

    The decomposition of dolomite into CaO and MgO was performed at 1073 K in vacuum and at 1273 K in an Ar atmosphere. The dolomite calcined in vacuum was found to have a higher specific surface area and a higher micropore volume when compared to the dolomite calcined in the Ar atmosphere. These pyrolysis products of dolomite were reacted with CO2 at 673 K for 21.6 ks. On the absorption of CO2, the formation of CaCO3 was observed. The degree of absorption of the dolomite calcined in vacuum was determined to be above 50%, which was higher than the degree of absorption of the dolomite calcined in the Ar atmosphere. The CO2 absorption and release procedures were repeated three times for the dolomite calcined in vacuum. The specific surface area and micropore volume of calcined dolomite decreased with successive repetitions of the CO2 absorption and release cycles leading to a decrease in the degree of absorption of CO2.

  7. Origin of Activity and Stability Enhancement for Ag3PO4 Photocatalyst after Calcination

    Directory of Open Access Journals (Sweden)

    Pengyu Dong

    2016-11-01

    Full Text Available Pristine Ag3PO4 microspheres were synthesized by a co-precipitation method, followed by being calcined at different temperatures to obtain a series of calcined Ag3PO4 photocatalysts. This work aims to investigate the origin of activity and stability enhancement for Ag3PO4 photocatalyst after calcination based on the systematical analyses of the structures, morphologies, chemical states of elements, oxygen defects, optical absorption properties, separation and transfer of photogenerated electron-hole pairs, and active species. The results indicate that oxygen vacancies (VO˙˙ are created and metallic silver nanoparticles (Ag NPs are formed by the reaction of partial Ag+ in Ag3PO4 semiconductor with the thermally excited electrons from Ag3PO4 and then deposited on the surface of Ag3PO4 microspheres during the calcination process. Among the calcined Ag3PO4 samples, the Ag3PO4-200 sample exhibits the best photocatalytic activity and greatly enhanced photocatalytic stability for photodegradation of methylene blue (MB solution under visible light irradiation. Oxygen vacancies play a significantly positive role in the enhancement of photocatalytic activity, while metallic Ag has a very important effect on improving the photocatalytic stability. Overall, the present work provides some powerful evidences and a deep understanding on the origin of activity and stability enhancement for the Ag3PO4 photocatalyst after calcination.

  8. Characterization of magnetic biochar amended with silicon dioxide prepared at high temperature calcination

    Directory of Open Access Journals (Sweden)

    Baig Shams Ali

    2016-09-01

    Full Text Available Calcination is considered to increase the hardness of composite material and prevent its breakage for the effective applications in environmental remediation. In this study, magnetic biochar amended with silicon dioxide was calcined at high temperature under nitrogen environment and characterized using various techniques. X-ray diffraction (XRD analysis revealed elimination of Fe3O4 peaks under nitrogen calcination and formation of Fe3Si and iron as major constituents of magnetic biochar-SiO2 composite, which demonstrated its superparamagnetic behavior (>80 A2·kg−1 comparable to magnetic biochar. Thermogravimetric analysis (TGA revealed that both calcined samples generated higher residual mass (>96 % and demonstrated better thermal stability. The presence of various bands in Fourier transform infrared spectroscopy (FT-IR was more obvious and the elimination of H–O–H bonding was observed at high temperature calcination. In addition, scanning electron microscopy (SEM images revealed certain morphological variation among the samples and the presence of more prominent internal and external pores, which then judged the surface area and pore volume of samples. Findings from this study suggests that the selective calcination process could cause useful changes in the material composites and can be effectively employed in environmental remediation measures.

  9. Transportation and transformation of mercury in a calcine profile in the Wanshan Mercury Mine, SW China.

    Science.gov (United States)

    Yin, Runsheng; Gu, Chunhao; Feng, Xinbin; Zheng, Lirong; Hu, Ningning

    2016-12-01

    Calcination of Hg ores has resulted in serious contamination of mercury (Hg) in the environment. To understand the mobilization of Hg in the calcine pile, the speciation of Hg in a profile of a large calcine pile in the Wanshan Mercury Mine, SW China was investigated using the X-ray absorption spectroscopy (XANES), to understand the mobilization of Hg in the calcine pile. Higher concentrations of Hg were observed at the 30-50 cm depth of the profile, corresponding to a cemented layer. This layer is observed in the entire pile, and was formed due to cementation of calcines. Hg species in calcines include cinnabar (α-HgS), metacinnabar (β-HgS), elemental Hg(0), and minor mercuric chloride (HgCl2), but these Hg species show dramatic changes in the profile. Variations in Hg speciation suggest that extensive mobilization of Hg can occur during weathering processes. We show that the cemented layer can prevent the leaching of Hg and the emission of Hg(0) from the pile. High MeHg concentrations were found near the cemented layer, indicating Hg methylation occurs. This study provides important insights into the environmental risk of Hg in mining areas. Copyright © 2016 Elsevier Ltd. All rights reserved.

  10. HWMA closure plan for the Waste Calcining Facility at the Idaho National Engineering Laboratory

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1996-05-01

    The Waste Calcining Facility (WCF) calcined and evaporated aqueous wastes generated from the reprocessing of spent nuclear fuel. The calciner operated from 1963 to 1981, primarily processing high level waste from the first cycle of spent fuel extraction. Following the calciner shutdown the evaporator system concentrated high activity aqueous waste from 1983 until 1987. In 1988, US Department of Energy Idaho Operations Office (DOE-ID) requested interim status for the evaporator system, in anticipation of future use of the evaporator system. The evaporator system has not been operated since it received interim status. At the present time, DOE-ID is completing construction on a new evaporator at the New Waste Calcining Facility (NWCF) and the evaporator at the WCF is not needed. The decision to not use the WCF evaporator requires Lockheed Idaho Technologies Company (LITCO) and DOE-ID to close these units. After a detailed evaluation of closure options, LITCO and DOE-ID have determined the safest option is to fill the voids (grout the vessels, cells and waste pile) and close the WCF to meet the requirements applicable to landfills. The WCF will be covered with a concrete cap that will meet the closure standards. In addition, it was decided to apply these closure standards to the calcining system since it is contained within the WCF building. The paper describes the site, waste inventory, closure activities, and post-closure care plans.

  11. ICPP calcined solids storage facility closure study. Volume III: Engineering design files

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1998-02-01

    The following information was calculated to support cost estimates and radiation exposure calculations for closure activities at the Calcined Solids Storage Facility (CSSF). Within the estimate, volumes were calculated to determine the required amount of grout to be used during closure activities. The remaining calcine on the bin walls, supports, piping, and floor was also calculated to approximate the remaining residual calcine volumes at different stages of the removal process. The estimates for remaining calcine and vault void volume are higher than what would actually be experienced in the field, but are necessary for bounding purposes. The residual calcine in the bins may be higher than was is experienced in the field as it was assumed that the entire bin volume is full of calcine before removal activities commence. The vault void volumes are higher as the vault roof beam volumes were neglected. The estimations that follow should be considered rough order of magnitude, due to the time constraints as dictated by the project`s scope of work. Should more accurate numbers be required, a new analysis would be necessary.

  12. Process analysis of CO{sub 2} capture from flue gas using carbonation/calcination cycles

    Energy Technology Data Exchange (ETDEWEB)

    Li, Z.S.; Cai, N.S.; Croiset, E. [Tsinghua University, Beijing (China). Dept. for Thermal Engineering

    2008-07-15

    Process analysis of CO{sub 2} capture from flue gas using Ca-based carbonation/calcination cycles is presented here. A carbonation/calcination system is composed essentially of two reactors (an absorber and a regenerator) with Ca-based sorbent circulating between the two reactors (assumed here as fluidized beds). CO{sub 2} is, therefore, transferred from the absorber to the regenerator. Because of the endothermicity of the calcination reaction, a certain amount of coal is burned with pure oxygen in the regenerator. Detailed mass balance, heat balance and cost of electricity and CO{sub 2} mitigation for the carbonation/calcination cycles with three Ca-based sorbents in dual fluidized beds were calculated and analyzed to study the effect of the Ca-based sorbent activity decay on CO{sub 2} capture from flue gas. The three sorbents considered were: limestone, dolomite and CaO/Ca{sub 12}Al{sub 14}O{sub 33} (75/25 wt %) sorbent. All results, including the amount of coal and oxygen required, are presented with respect to the difference in calcium oxide conversion between the absorber and the regenerator, which is an important design parameter. Finally, costs of electricity and CO{sub 2} mitigation costs using carbonation/calcination cycles for the three sorbents were estimated. The results indicate that the economics of the carbonation/calcination process compare favorably with competing technologies for capturing CO{sub 2}.

  13. Carbon Dioxide Absorption and Release Properties of Pyrolysis Products of Dolomite Calcined in Vacuum Atmosphere

    Science.gov (United States)

    Wang, Fei; Kuzuya, Toshihiro; Hirai, Shinji; Li, Jihua; Li, Te

    2014-01-01

    The decomposition of dolomite into CaO and MgO was performed at 1073 K in vacuum and at 1273 K in an Ar atmosphere. The dolomite calcined in vacuum was found to have a higher specific surface area and a higher micropore volume when compared to the dolomite calcined in the Ar atmosphere. These pyrolysis products of dolomite were reacted with CO2 at 673 K for 21.6 ks. On the absorption of CO2, the formation of CaCO3 was observed. The degree of absorption of the dolomite calcined in vacuum was determined to be above 50%, which was higher than the degree of absorption of the dolomite calcined in the Ar atmosphere. The CO2 absorption and release procedures were repeated three times for the dolomite calcined in vacuum. The specific surface area and micropore volume of calcined dolomite decreased with successive repetitions of the CO2 absorption and release cycles leading to a decrease in the degree of absorption of CO2. PMID:25136696

  14. Adsorptive removal of phosphate from aqueous solutions using raw and calcinated dolomite.

    Science.gov (United States)

    Karaca, S; Gürses, A; Ejder, M; Açikyildiz, M

    2006-02-06

    This study explored the feasibility of utilizing raw and calcinated dolomite under CO2 atmosphere for phosphate removal in laboratory experiments. The experimental work emphasized the evaluation of phosphate adsorption characteristics of this adsorbent material. Studies were conducted to delineate the effect of contact time, initial phosphate concentration, temperature, pH, stirring speed, adsorbent dose and calcination temperature. Phosphate removal decreased with increasing temperature and slightly increased with increasing of pH. The observed decrease in the adsorption capacity with increase of the temperature from 20 to 40 and to 60 degrees C indicates that the low temperatures favor the phosphate removal by adsorption onto dolomite. Phosphate removal was seen to decrease with increasing calcination temperature due to the structural changes occurring in the structure and pore size distribution of dolomite samples during calcination. The experimental data obtained were applied to the Freundlich, Langmuir, BET, Halsey, Harkins-Jura, Smith and Henderson isotherm equations to test the fit of these equations to raw and calcinated dolomite samples. By considering the experimental results and adsorption models applied in this study, it can be concluded that adsorption of phosphate occurs predominantly through physical interactions, and the dolomite sample has a heteroporous structure. The large values of the constants for Henderson equation and the high value of y(m) obtained from BET equation indicate the microporous structure is more stable in raw and calcinated dolomite samples.

  15. Effect of Calcination Temperature on Morphological and Topography of Nickel-Alumina Thin Film

    Directory of Open Access Journals (Sweden)

    Sarwani Khairul Ilman

    2016-01-01

    Full Text Available Dip coating process promises good potential of nickel-alumina catalyst deposition on metal substrate for various applications especially in gas conversion reaction. This study was conducted to investigate the effect of different calcination temperature on nickel-alumina catalysts thin film formation. Four different calcination temperature were used, which are 300°C, 400°C, 500°C and 600°C. The calculation process was conducted for a duration of 90 minutes. The deposited thin films were characterized using Atomic Force Microscopy (AFM and X-ray diffraction (XRD equipment. The AFM result showed that the surface roughness of the nickel-alumina increase proportionally from 56 to 275 nm when the calcination temperature increased from 300 to 600°C. From an observation at high calcination temperature, the atom of grains assisted diffusion at the crystallite point causing grain with lower surface energy become larger. As the calcination temperature increase, the surface profile becomes rough and uneven representing high surface roughness. Thus, the effect of calcination temperature greatly influences the surface roughness of the nickel-alumina thin film.

  16. Determination of the Rate of Formation of Hydroceramic Waste Forms made with INEEL Calcined Wastes

    Energy Technology Data Exchange (ETDEWEB)

    Barry Scheetz; Johnson Olanrewaju

    2001-10-15

    The formulation, synthesis, characterization and hydration kinetics of hydroceramic waste forms designed as potential hosts for existing INEEL calcine high-level wastes have been established as functions of temperature and processing time. Initial experimentations were conducted with several aluminosilicate pozzolanic materials, ranging from fly ash obtained from various power generating coal and other combustion industries to reactive alumina, natural clays and ground bottled glass powders. The final selection criteria were based on the ease of processing, excellent physical properties and chemical durability (low-leaching) determined from the PCT test produced in hydroceramic. The formulation contains vermiculite, Sr(NO32), CsC1, NaOH, thermally altered (calcined natural clay) and INEEL simulated calcine high-level nuclear wastes and 30 weight percent of fluorinel blend calcine and zirconia calcine. Syntheses were carried out at 75-200 degree C at autogeneous water pressure (100% relative humidity) at various time intervals. The resulting monolithic compact products were hard and resisted breaking when dropped from a 5 ft height. Hydroceramic host mixed with fluorinel blend calcine and processed at 75 degree C crumbled into rice hull-side grains or developed scaly flakes. However, the samples equally possessed the same chemical durability as their unbroken counterparts. Phase identification by XRD revealed that hydroceramic host crystallized type zeolite at 75-150 degree C and NaP1 at 175-200 degree C in addition to the presence of quartz phase originating from the clay reactant. Hydroceramic host mixed with either fluorinel blend calcine or zirconia calcine crystallized type A zeolite at 75-95 degree C, formed a mixture of type A zeolite and hydroxysodalite at 125-150 degree C and hydroxysodalite at 175-200 degree C. Quartz, calcium fluoride and zirconia phases from the clay reactant and the two calcine wastes were also detected. The PCT test solution

  17. Spray Calciner/In-Can Melter high-level waste solidification technical manual

    Energy Technology Data Exchange (ETDEWEB)

    Larson, D.E. (ed.)

    1980-09-01

    This technical manual summarizes process and equipment technology developed at Pacific Northwest Laboratory over the last 20 years for vitrification of high-level liquid waste by the Spray Calciner/In-Can Melter process. Pacific Northwest Laboratory experience includes process development and demonstration in laboratory-, pilot-, and full-scale equipment using nonradioactive synthetic wastes. Also, laboratory- and pilot-scale process demonstrations have been conducted using actual high-level radioactive wastes. In the course of process development, more than 26 tonnes of borosilicate glass have been produced in 75 canisters. Four of these canisters contained radioactive waste glass. The associated process and glass chemistry is discussed. Technology areas described include calciner feed treatment and techniques, calcination, vitrification, off-gas treatment, glass containment (the canister), and waste glass chemistry. Areas of optimization and site-specific development that would be needed to adapt this base technology for specific plant application are indicated. A conceptual Spray Calciner/In-Can Melter system design and analyses are provided in the manual to assist prospective users in evaluating the process for plant application, to provide equipment design information, and to supply information for safety analyses and environmental reports. The base (generic) technology for the Spray Calciner/In-Can Melter process has been developed to a point at which it is ready for plant application.

  18. Removal of Dissolved Silica using Calcinated Hydrotalcite in Real-life Applications.

    Energy Technology Data Exchange (ETDEWEB)

    Sasan, Koroush [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Brady, Patrick Vane. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Krumhansl, James L. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Nenoff, Tina M. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Sasan, Koroush [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Sasan, Koroush [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2017-09-01

    Water shortages are a growing global problem. Reclamation of industrial and municipal wastewater will be necessary in order to mitigate water scarcity. However, many operational challenges, such as silica scaling, prevent large scale water reuse. Previously, our team at Sandia has demonstrated the use of selective ion exchange materials, such as calcinated hydrotalcite (HTC, (Mg 6 Al 2 (OH) 16 (CO 3 )*4H 2 O)), for the low cost removal of silica from synthetic cooling tower water. However, it is not currently know if calcinated HTC has similar capabilities in realistic applications. The purpose of this study was to investigate the ability of calcinated HTC to remove silica from real cooling tower water. This was investigated under both batch and continuous conditions, and in the presence of competing ions. It was determined that calcinated HTC behaved similarly in real and synthetic cooling tower water; the HTC is highly selective for the silica even in the presence of competing cations. Therefore, the data concludes that calcinated HTC is a viable anti-scaling pretreatment for the reuse of industrial wastewaters.

  19. Mechanical and Thermal Properties of Polypropylene Reinforced by Calcined and Uncalcined Zeolite

    Directory of Open Access Journals (Sweden)

    Nurdin Bukit

    2013-04-01

    Full Text Available This study was carried out to compare mechanical and thermal properties of polypropylene (PP reinforced with uncalcined and calcined zeolites. The PP samples were reinforced with zeolites at various quantities of 2, 4, and 6 (wt %. The comparison of the two types of zeolite was based  on mechanical properties, including tensile strength, elongation at break, and Young’s modulus, and thermal characteristics analyzed using DSC, and DTA/TGA technique. The results obtained clearly revealed that both zeolites were able to significantly increase tensile strength and Young’s modulus of the samples, with calcined zeolite was found to work better. Addition of calcined zeolite was found to result in increased fracture elongation of the samples reinforced with up to 4 wt% zeolite but decreased sharply for the sample reinforced with 6 wt% zeolite, while for the samples reinforced with uncalcined zeolite, no consistent trend was observed. Thermal analyses demonstrated that the samples reinforced with calcined zeolite are more resistant to thermal treatment than those reinforced with uncalcined zeolite, as indicated by their higher decomposition temperature. DSC analysis revealed that there  was no significant difference  of the melting points of the samples was observed, but the effect of the quantity of zeolite on enthalphy was quite evident, in which the enthalpies of the samples reinforced with calcined zeolites were relatively lower than those of the samples reinforced with uncalcined zeolites. 

  20. Incorporation of Polymers into Calcined Clays as Improved Thermal Insulating Materials for Construction

    Directory of Open Access Journals (Sweden)

    Serina Ng

    2017-01-01

    Full Text Available Calcined clay is a Type Q supplementary cementing material according to EN197-1:2000. It possesses lower thermal conductivity than cement. To further improve its thermal insulation property, polymer-calcined clay complexes (PCCs were produced in a one-pot synthesis. Two contrasting polymers, polystyrene (PS and polyethylene glycol (PEG, were employed. The hydrophilicity of the polymers influenced the thermal conductivity of PCC. Hydrophilic PEG entrapped more water molecules on clay layers than the hydrophobic PS, making PEG-PCC more thermally conducting than PS-PCC. Contaminants in calcined clays played a role in affecting the overall thermal conductivity. PCC can improve thermal insulation properties for future construction applications.

  1. CALCINATION TEMPERATURE EFFECTS ON OPTICAL PROPERTIES OF NANO-POROUS SILICA THIN FILMS

    Directory of Open Access Journals (Sweden)

    Mohammadreza Mojab

    2015-06-01

    Full Text Available Silica nano-porous thin films at various calcination temperatures were deposited on glass substrates with a layer by layer method. The structure, morphology, surface composition, transmittance and reflectance of the films were investigated by X-ray diffraction, field emission scanning electron microscopy, attenuated total reflectance fourier transform infrared spectroscopy and UV-VIS-NIR spectrophotometer, respectively. The results indicated that the transmittance of the films is increased by increasing the calcinations temperatures to 300oC and at higher temperature, it is decreased. The deposition of silica nano-porous film on the glass at the optimum calcination temperature (300oC decreased refractive index of the glass at a wavelength of 550 nm from 1.5 to 1.37.

  2. Effect of fly ash preliminary calcination on the properties of geopolymer.

    Science.gov (United States)

    Temuujin, J; van Riessen, A

    2009-05-30

    The influence of preliminary calcination of fly ashes on the geopolymerisation process has been studied. Preliminary calcination at 500 and 800 degrees C causes decarbonation of the fly ash while it also leads to a decrease of the amorphous content of the fly ashes from 60 to 57%. Geopolymer prepared using raw fly ash exhibited a compressive strength 55.7(9.2)MPa, while for 500 and 800 degrees C calcined samples it reduced to 54(5.8) and 44.4(5.4)MPa, respectively. The decrease in compressive strength of the geopolymers is discussed in terms of partial surface crystallisation of the fly ash particles. Reactivity of the fly ash also has been correlated with the shrinkage rate and presence of efflorescence on the surface of geopolymers.

  3. Effect of Calcination Temperature on the Alumina-Zirconia Nanostructures Prepared by Combustion Synthesis

    Directory of Open Access Journals (Sweden)

    M. Jafar Tafreshi

    2012-12-01

    Full Text Available In this research, a sol gel autocaombustion route has been proposed to synthesize alumina-zirconia composite powders, using ammonium bicarbonate as a new fuel. Then the effect of calcination temperature on phase transformation and crystallite sizes was investigated. To characterize the products XRD, TEM and BET analyses were used. XRD patterns of as-synthesized powder and calcined powders at 1100 ◦C and 1200 ◦C showed t-ZrO2 phase with small crystallite sizes (sintered at 1300 ◦C and the particle sizes after calcination were 14.90 nm and 50 nm for ZrO2 and Al2O3 phases, respectively as calculated from XRD and the transformation of t-ZrO2 to m-ZrO2 started at 1300 ◦C. TEM micrograph of as-synthesized powder revealed nanosize spherical particles of about 8 nm.

  4. Thermodynamics of Protein Aggregation

    Science.gov (United States)

    Osborne, Kenneth L.; Barz, Bogdan; Bachmann, Michael; Strodel, Birgit

    Amyloid protein aggregation characterizes many neurodegenerative disorders, including Alzheimer's, Parkinson's, and Creutz- feldt-Jakob disease. Evidence suggests that amyloid aggregates may share similar aggregation pathways, implying simulation of full-length amyloid proteins is not necessary for understanding amyloid formation. In this study we simulate GNNQQNY, the N-terminal prion-determining domain of the yeast protein Sup35 to investigate the thermodynamics of structural transitions during aggregation. We use a coarse-grained model with replica-exchange molecular dynamics to investigate the association of 3-, 6-, and 12-chain GNNQQNY systems and we determine the aggregation pathway by studying aggregation states of GN- NQQNY. We find that the aggregation of the hydrophilic GNNQQNY sequence is mainly driven by H-bond formation, leading to the formation of /3-sheets from the very beginning of the assembly process. Condensation (aggregation) and ordering take place simultaneously, which is underpinned by the occurrence of a single heat capacity peak only.

  5. ICPP radioactive liquid and calcine waste technologies evaluation final report and recommendation

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1995-04-01

    Using a formalized Systems Engineering approach, the Latched Idaho Technologies Company developed and evaluated numerous alternatives for treating, immobilizing, and disposing of radioactive liquid and calcine wastes at the Idaho Chemical Processing Plant. Based on technical analysis data as of March, 1995, it is recommended that the Department of Energy consider a phased processing approach -- utilizing Radionuclide Partitioning for radioactive liquid and calcine waste treatment, FUETAP Grout for low-activity waste immobilization, and Glass (Vitrification) for high-activity waste immobilization -- as the preferred treatment and immobilization alternative.

  6. Distinguishing aggregate formation and aggregate clearance using cell based assays

    NARCIS (Netherlands)

    E. Eenjes, E.; J.M. Dragich; H. Kampinga (Harm); A. Yamamoto, A.

    2016-01-01

    textabstractThe accumulation of ubiquitinated proteinaceous inclusions represents a complex process, reflecting the disequilibrium between aggregate formation and aggregate clearance. Although decreasing aggregate formation or augmenting aggregate clearance will ultimately lead to diminished

  7. Influence of calcinated and non calcinated nanobioglass particles on hardness and bioactivity of sol-gel-derived TiO2-SiO2 nano composite coatings on stainless steel substrates.

    Science.gov (United States)

    Dadash, Mohammad Saleh; Karbasi, Saeed; Esfahani, Mojtaba Nasr; Ebrahimi, Mohammad Reza; Vali, Hojatollah

    2011-04-01

    Thick films of calcinated and non calcinated nanobioglass (NBG)-titania composite coatings were prepared on stainless steel substrates by alkoxide sol-gel process. Dip-coating method was used for the films preparation. The morphology, structure and composition of the nano composite films were evaluated using environmental scanning electron microscope, X-ray diffraction and Fourier transform infrared spectroscope. The SEM investigation results showed that prepared thick NBG-titania films are smooth and free of macrocracking, fracture or flaking. The grain size of these films was uniform and nano scale (50-60 nm) which confirmed with TEM. Also FTIR confirmed the presence of Si-O-Si bands on the calcinated NBG-titania films. The hardness of the prepared films (TiO(2)-calcinated NBG and TiO(2)-Non calcinated NBG) was compared by using micro hardness test method. The results verified that the presence of calcinated NBG particles in NBG-titania composite enhanced gradually the mechanical data of the prepared films. The in vitro bioactivity of these films was discussed based on the analysis of the variations of Ca and P concentrations in the simulated body fluid (SBF) and their surface morphologies against immersion time. Surface morphology and Si-O-Si bands were found to be of great importance with respect to the bioactivity of the studied films. The results showed that calcinated NBG-titania films have better bioactivity than non calcinated NBG-titania films.

  8. Effect of the rate of calcination of kaolin on the properties of metakaolin-based geopolymers

    Directory of Open Access Journals (Sweden)

    B.B. Kenne Diffo

    2015-03-01

    Full Text Available Kaolin samples of the same mass were treated at 700 °C for the same duration of 30 min by varying the rate of calcination (1, 2.5, 5, 10, 15 and 20 °C/min in order to obtain metakaolins which were used to produce geopolymers. Depending on the nature of each type of material, kaolin, metakaolins and geopolymers were characterized using thermal analysis, chemical analysis, XRD, FTIR, particle size distribution, specific surface area, bulk density, setting time and compressive strength. FTIR and XRD analyses showed that metakaolins except at 1 °C/min contained residual kaolinite whose quantity increased with the rate of calcination of kaolin and which influenced the characteristics of geopolymers. Thus as the rate of calcination of kaolin increased, the setting time increased (226 min (rate of 1 °C/min–773 min (rate of 20 °C/min while the compressive strength reduced (49.4 MPa (rate of 1 °C/min–20.8 MPa (rate of 20 °C/min. From the obtained results the production of geopolymers having high compressive strength along with low setting time requires that the calcination of kaolin be carried out at a low rate.

  9. Zeolite Beta: The Relationship Between Calcination Procedure, Aluminum Configuration and Lewis Acidity

    NARCIS (Netherlands)

    Koningsberger, D.C.; Kunkeler, P.J.; Zuurdeeg, B.J.; Waal, J.C. van der; Bokhoven, J.A. van; Bekkum, H. van

    1998-01-01

    Zeolite Beta was calcined under a variety of carefully controlled conditions to study the influence of (hydro)thermal treatments on the catalytic activity of zeolite Beta in the Lewis acid-catalyzed Meerwein-Ponndorf-Verley reduction of ketones. The activity of (H)Beta can be increased by several

  10. Oxidative dehydrogenation of ethylbenzene to styrene over alumina : effect of calcination

    NARCIS (Netherlands)

    Nederlof, Christian; Zarubina, Valeriya; Melian-Cabrera, Ignacio; Heeres, Hero Jan (Eric); Kapteijn, Freek; Makkee, Michiel

    2013-01-01

    Commercially available gamma-Al2O3 was calcined at temperatures between 500 and 1200 degrees C and tested for its performance in the oxidative ethylbenzene dehydrogenation (ODH) over a wide range of industrially-relevant conditions. The original gamma-Al2O3, as well as Z- and alpha-Al2O3, were

  11. Enhanced pyroelectric properties of PZT/PVDF-TrFE composites using calcined PZT ceramic powders

    Science.gov (United States)

    Wu, Chuan-Gui; Cai, Guang-Qiang; Luo, Wen-Bo; Peng, Qiang-Xiang; Sun, Xiang-Yu; Zhang, Wan-Li

    2013-04-01

    The effects of calcined lead-zirconate-titanate (PZT) powders on the electric properties of PZT/polyvinylidene-trifluorethylene copolymer (PVDF-TrFE) composites thick films were studied in this paper. Firstly, the PZT powders synthesized by hydrothermal method were calcined at different temperatures ranging from 300°C to 900°C, and then the PZT/PVDF-TrFE composites films were produced by casting PZT/PVDF-TrFE suspension onto the indium-tin-oxide (ITO)-coated glass substrates. Electric properties, including dielectric and pyroelectric performances of thick films consisting of PZT powders calcined at different temperatures were tested. The highest pyroelectric coefficient obtained in the sample using 700°C calcined PZT powders was 96 μCm-2K-1, which was 20% higher than the composites made of uncalcined powders. Additionally, the highest detectivity figure-of-merit (FOM) (FD) of the composite was 1.36 × 10-5Pa-1/2, which increased about 13.5% compared to the one using uncalcined powders.

  12. Effect of calcination conditions of pork bone sludge on behaviour of ...

    Indian Academy of Sciences (India)

    The paper presents in vitro (in SBF) behaviour of hydroxyapatite (HAp) obtained from pork bone sludge from meat plant via two essentially different calcination methods using a stationary, electrically heated chamber oven and enlarged laboratory scale rotary kiln designed by the authors, heated by gas combustion methods ...

  13. Hydroxyapatite nanoparticles: electrospinning and calcination of hydroxyapatite/polyvinyl butyral nanofibers and growth kinetics

    NARCIS (Netherlands)

    Zakaria, S.M.; Zein, S.H. Sharif; Othman, M.R.; Jansen, J.A.

    2013-01-01

    Electrospinning of hydroxyapatite (HA)/polyvinyl butyral solution resulted in the formation of fibers with average diameter of 937-1440 nm. These fibers were converted into HA nanoparticles with size <100 nm after undergoing calcination treatment at 600 degrees C. The diameter of the fiber was

  14. COMPARATIVE MAGNETIC AND PHOTOCATALYTIC PROPERTIES OF COPRECIPITATED ZINC FERRITE NANOPARTICLES BEFORE AND AFTER CALCINATION

    Directory of Open Access Journals (Sweden)

    M. Ebrahimi

    2017-03-01

    Full Text Available In this work, the effects of co-precipitation temperature and post calcination on the magnetic properties and photocatalytic activities of ZnFe2O4 nanoparticles were investigated. The structure, magnetic and optical properties of zinc ferrite nanoparticles were characterized by X-ray diffraction (XRD, vibrating sample magnetometry and UV–Vis spectrophotometry techniques.  The XRD results showed that the coprecipitated as well as calcined nanoparticles are single phase with partially inverse spinel structures. The magnetization and band gap decreased with the increasing of co-precipitation temperature through the increasing of the crystallite size. However, the post calcination at 500 °C was more effective on the decreasing of magnetization and band gap. Furthermore, photocatalytic activity of zinc ferrite nanoparticles was studied by the degradation of methyl orange under UV-light irradiation. Compare with the coprecipitated ZnFe2O4 nanoparticles with 5% degradation of methyl orange after 5 h UV-light light radiation, the calcined ZnFe2O4 nanoparticles exhibited a better photocatalytic activity with 20% degradation.

  15. Influence of calcined mud on the mechanical properties and shrinkage of self-compacting concrete

    Directory of Open Access Journals (Sweden)

    Fatima Taieb

    2018-01-01

    Full Text Available The use of SCC has a particular interest in terms of sustainable development. Indeed, their specific formulation leads to a greater volume of dough than for common concretes, thus, a larger quantity of cement. However, for economical, ecological and technical reasons, it is sought to limit their cement content [1]. It is therefore necessary to almost always use mineral additions as a partial replacement for cement because the technology of self-compacting concretes can consume large quantities of fines, in this case calcinated mud issued from dams dredging sediments that can give and/or ameliorate characteristics and performances of this type of concretes. Four SCCs had been formulated from the same composition where the only percentage of calcinated mud of Chorfa (west of Algeria dam changed (0%, 10%, 20% and 30%. The effect of calcinated mud on characteristics at fresh state of SCC according to AFGC was quantified. Mechanical strengths and shrinkage deformation (total, autogenous, drying were evaluated. The results show the possibility to make SCCs with different dosages of calcinated mud having strengths that can defy those of the control SCC. The analysis of free deformations indicates the beneficial impact of the mud by contributing to decrease the amplitudes of the shrinkage compared to those of the control SCC.

  16. CO{sub 2} capture behavior of shell during calcination/carbonation cycles

    Energy Technology Data Exchange (ETDEWEB)

    Li, Y.J.; Zhao, C.S.; Chen, H.C.; Duan, L.B.; Chen, X.P. [School of Energy and Environment, Southeast University, Nanjing (China)

    2009-08-15

    The cyclic carbonation performances of shells as CO{sub 2} sorbents were investigated during multiple calcination/carbonation cycles. The carbonation kinetics of the shell and limestone are similar since they both exhibit a fast kinetically controlled reaction regime and a diffusion controlled reaction regime, but their carbonation rates differ between these two regions. Shell achieves the maximum carbonation conversion for carbonation at 680-700 C. The mactra veneriformis shell and mussel shell exhibit higher carbonation conversions than limestone after several cycles at the same reaction conditions. The carbonation conversion of scallop shell is slightly higher than that of limestone after a series of cycles. The calcined shell appears more porous than calcined limestone, and possesses more pores >230 nm, which allow large CO{sub 2} diffusion-carbonation reaction rates and higher conversion due to the increased surface area of the shell. The pores of the shell that are greater than 230 nm do not sinter significantly. The shell has more sodium ions than limestone, which probably leads to an improvement in the cyclic carbonation performance during the multiple calcination/carbonation cycles. (Abstract Copyright [2009], Wiley Periodicals, Inc.)

  17. Actinide partitioning from actual ICPP dissolved zirconium calcine using the TRUEX solvent

    Energy Technology Data Exchange (ETDEWEB)

    Brewer, K.N.; Herbst, R.S.; Tranter, T.J. [and others

    1995-05-01

    The TRansUranic EXtraction process (TRUEX), as developed by E.P. Horwitz and coworkers at Argonne National Laboratory (ANL), is being evaluated as a TRU extraction process for Idaho Chemical Processing Plant (ICPP) wastes. A criteria that must be met during this evaluation, is that the aqueous raffinate must be below the 10 nCi/g limit specified in 10 CFR 61.55. A test was performed where the TRUEX solvent (0.2 M octyl(phenyl)-N-N-diisobutyl-carbamoylmethyl-phosphine oxide (CMPO), and 1.4 M tributylphosphate (TBP) in an Isopar-L diluent) was contacted with actual ICPP dissolved zirconium calcine. Two experimental flowsheets were used to determine TRU decontamination factors, and TRU, Zr, Fe, Cr, and Tc extraction, scrub, and strip distribution coefficients. Results from these two flowsheets show that >99.99% of the TRU alpha activity was removed from the acidic feed after three contacts with the TRUEX solvent (fresh solvent being used for each contact). The resulting aqueous raffinate solution contained an approximate TRU alpha activity of 0.02 nCi/g, which is well below the non-TRU waste limit of 10 nCi/g specified in 10 CFR 61.55. Favorable scrub and strip distribution coefficients were also observed for Am-241, Pu-238, and Pu-239, indicating the feasibility of recovering these isotopes from the TRUTEX solvent. A solution of 0.04 M 1-hydroxyethane-1,1-diphosphonic acid (HEDPA) in 0.04 M HNO{sub 3} was used to successfully strip the TRUs from the TRUEX solvent. The results of the test using actual ICPP dissolved zirconium calcine, and subsequent GTM evaluation, show the feasibility of removing TRUs from the dissolved zirconium calcine with the TRUEX solvent and the deleterious effects zirconium poses with the ICPP zirconium calcine waste. Test results using actual ICPP zirconium calcine reveal the necessity of preventing zirconium from following the TRUs.

  18. Actinide partitioning studies using dihexyl-N,N-diethycarbamolymehtyl phosphonate and dissolved zirconium calcine

    Energy Technology Data Exchange (ETDEWEB)

    Brewer, K.N.; Herbst, R.S.; Law, J.D.; Garn, T.G.; Tillotson, R.D.; Todd, T.A.

    1996-01-01

    A baseline flowsheet capable of partitioning the transuranic (TRU) elements from dissolved zirconium calcines has been developed. The goal of the TRU partitioning process is to remove the TRUs from solutions of dissolved zirconium calcines to below the 10 CFR 61.55 Class A waste limit of 10 nCi/g. Extraction, scrub, strip, and wash distribution coefficients for several elements, including the actinides, were measured in the laboratory by performing equal volume batch contacts. A solvent containing diheyl-N, N- diethylcarbamoylmethyl phosphonate (CMP), tributylphosphate (TBP), and a branched chain hydrocarbon as the diluent were used to develop this process. A non-radioactive zirconium pilot-plant calcine was spiked with the TRUs, U, Tc, or a radioactive isotope of zirconium to simulate the behavior of these elements in actual dissolved zirconium calcine feed. Distribution coefficient data obtained from laboratory testing were used to recommend: (1) solvent composition, (2) scrub solutions capable of selectively removing extracted zirconium while minimizing actinide recycle, (3) optimized strip solutions which quantitatively recover extracted actinides, and (4) feed adjustments necessary for flowsheet efficiency. Laboratory distribution coefficients were used in conjunction with the Generic TRUEX Model (GTM) to develop and recommend a flowsheet for testing in the 5.5-cm Centrifugal Contractor Mockup. GTM results indicate that the recommended flowsheet should remove the actinides from dissolved zirconium calcine feed to below the Class A waste limit of 10 nCi/g. Less than 0.01 wt% of the extracted zirconium will report to the high- activity waste (HAW) fraction using the 0.05 M H{sub 2}C{sub 2}O{sub 4} in 3.0 M HNO{sub 3} scrub, and greater than 99% of the extracted actinides are recovered with 0.001 M HEDPA.

  19. Effects of calcination treatment on the morphology, crystallinity, and photoelectric properties of all-solid-state dye-sensitized solar cells assembled by TiO2 nanorod arrays.

    Science.gov (United States)

    Sun, Xianmiao; Sun, Qiong; Li, Yang; Sui, Lina; Dong, Lifeng

    2013-11-14

    TiO2 has been extensively investigated due to its unique photoelectric properties. In this study, oriented single-crystal rutile TiO2 nanorod arrays were synthesized and then calcined at different temperatures in the atmosphere. The morphology and crystalline characterization indicated that the length of TiO2 nanorods increased rapidly and the nanorods became aggregated and fragile after calcination, yet the sintering treatment seemed to have almost no effect on the crystallinity. To obtain the all-solid-state, dye-sensitized solar cells (DSSCs), a newly reported solid inorganic semiconductor, CsSnI2.95F0.05, was employed as the electrolyte, and the Pt deposited on the conductive side of the fluorine-doped tin oxide (FTO) glass substrate was used as the counter-electrode. The effects of the calcination treatment on the photoelectric properties of the solar cells, including external quantum efficiency (EQE), open circuit voltage (V(OC)), short-circuit current (J(SC)), and photoelectric conversion efficiency (η), were investigated under the illumination of a solar simulator. As a result, all of the EQE, V(OC), J(SC), and η values of the cells first increased and then declined with the increase of calcination temperatures, and the highest η of 2.81% was obtained by the cell assembled with its TiO2 electrode sintered at 450 °C for 3 h, a value almost 2.5 times that of the non-sintered sample (1.1%).

  20. Alliance between chemical industry Astral Calcining, India, and energy company E.On Benelux; Verbond chemie en energie [tussen Astral Calcining, India en E.On Benelux

    Energy Technology Data Exchange (ETDEWEB)

    Roggen, M. (ed.)

    2003-03-01

    The Indian chemical concern Astral Calcining (produces carbon for the aluminium industry) will supply high-pressure steam to the energy company E.ON Benelux, to be used by Lyondell Bayer (producer of propylene oxide). In exchange, Astral will receive electricity from E.On Benelux. This is a unique co-operation between companies with different production processes and cultures. [Dutch] Het Indiase chemieconcern Astral gaat aan E.ON Benelux hogedruk stoom leveren die bestemd is voor Lyondell Bayer. In ruil daarvoor ontvangt Astral elektriciteit. Een unieke samenwerking tussen concerns met totaal andere productieprocessen en uiteenlopende culturen.

  1. Cyclic calcination/carbonation looping of dolomite modified with acetic acid for CO{sub 2} capture

    Energy Technology Data Exchange (ETDEWEB)

    Li, Ying-jie; Zhao, Chang-sui; Duan, Lun-bo; Liang, Cai; Li, Qing-zhao; Zhou, Wu; Chen, Hui-chao [Key Laboratory of Coal Power Generation and Combustion Technology of Ministry of Education, Southeast University, Nanjing 210096 (China)

    2008-12-15

    The dolomite modified with acetic acid solution was proposed as a CO{sub 2} sorbent for calcination/carbonation cycles. The carbonation conversions for modified and original dolomites in a twin fixed-bed reactor system with increasing the numbers of cycles were investigated. The carbonation temperature in the range of 630 C-700 C is beneficial to the carbonation reaction of modified dolomite. The carbonation conversion for modified dolomite is significantly higher than that for original sorbent at the same reaction conditions with increasing numbers of reaction cycles. The modified dolomite exhibits a carbonation conversion of 0.6 after 20 cycles, while the unmodified sorbent shows a conversion of 0.26 at the same reaction conditions, which is calcined at 920 C and carbonated at 650 C. At the high calcination temperature over 920 C modified dolomite can maintain much higher conversion than unmodified sorbent. The mean grain size of CaO derived from modified dolomite is smaller than that from original sorbent with increasing numbers of reaction cycles. The calcined modified dolomite possesses greater surface area and pore volume than calcined original sorbent during the multiple cycles. The pore volume and pore area distributions for calcined modified dolomite are also superior to those for calcined unmodified sorbent during the looping cycle. The modified dolomite is proved as a new and promising type of regenerable CO{sub 2} sorbent for industrial applications. (author)

  2. Influence of calcination temperature on structural and magnetic properties of nanocomposites formed by Co-ferrite dispersed in sol-gel silica matrix using tetrakis(2-hydroxyethyl orthosilicate as precursor

    Directory of Open Access Journals (Sweden)

    Gharagozlou Mehrnaz

    2011-04-01

    Full Text Available Abstract Effects of calcination temperatures varying from 400 to 1000°C on structural and magnetic properties of nanocomposites formed by Co-ferrite dispersed in the sol-gel silica matrix using tetrakis(2-hydroxyethyl orthosilicate (THEOS as water-soluble silica precursor have been investigated. Studies carried out using XRD, FT-IR, TEM, STA (TG-DTG-DTA and VSM techniques. Results indicated that magnetic properties of samples such as superparamagnetism and ferromagnetism showed great dependence on the variation of the crystallinity and particle size caused by the calcination temperature. The crystallization, saturation magnetization Ms and remenant magnetization Mr increased as the calcination temperature increased. But the variation of coercivity Hc was not in accordance with that of Ms and Mr, indicating that Hc is not determined only by the crystallinity and size of CoFe2O4 nanoparticles. TEM images showed spherical nanoparticles dispersed in the silica network with sizes of 10-30 nm. Results showed that the well-established silica network provided nucleation locations for CoFe2O4 nanoparticles to confinement the coarsening and aggregation of nanoparticles. THEOS as silica matrix network provides an ideal nucleation environment to disperse CoFe2O4 nanoparticles and thus to confine them to aggregate and coarsen. By using THEOS as water-soluble silica precursor over the currently used TEOS and TMOS, the organic solvents are not needed owing to the complete solubility of THEOS in water. Synthesized nanocomposites with adjustable particle sizes and controllable magnetic properties make the applicability of Co-ferrite even more versatile.

  3. Platelet activation and aggregation

    DEFF Research Database (Denmark)

    Jensen, Maria Sander; Larsen, O H; Christiansen, Kirsten

    2013-01-01

    This study introduces a new laboratory model of whole blood platelet aggregation stimulated by endogenously generated thrombin, and explores this aspect in haemophilia A in which impaired thrombin generation is a major hallmark. The method was established to measure platelet aggregation initiated...

  4. Aggregates from mineral wastes

    Directory of Open Access Journals (Sweden)

    Baic Ireneusz

    2016-01-01

    Full Text Available The problem concerning the growing demand for natural aggregates and the need to limit costs, including transportation from remote deposits, cause the increase in growth of interest in aggregates from mineral wastes as well as in technologies of their production and recovery. The paper presents the issue related to the group of aggregates other than natural. A common name is proposed for such material: “alternative aggregates”. The name seems to be fully justified due to adequacy of this term because of this raw materials origin and role, in comparison to the meaning of natural aggregates based on gravel and sand as well as crushed stones. The paper presents characteristics of the market and basic application of aggregates produced from mineral wastes, generated in the mining, power and metallurgical industries as well as material from demolished objects.

  5. Cobalt-lanthanum catalyst precursors for ammonia synthesis: determination of calcination temperature and storage conditions

    Directory of Open Access Journals (Sweden)

    Zybert Magdalena

    2017-06-01

    Full Text Available A thermal decomposition of a cobalt-lanthanum catalyst precursor containing a mixture of cobalt and lanthanum compounds obtained by co-precipitation were studied using thermal analysis coupled with mass spectrometry (TG-MS. Studies revealed that the calcination in air at 500°C is sufficient to transform the obtained cobalt precipitate into Co3O4, but it leads to only partial decomposition of lanthanum precipitate. In order to obtain Co/La catalyst precursor containing La2O3 the calcination in air at the temperature about 800°C is required. However, it is unfavorable from the point of view of textural properties of the catalyst precursor. A strong effect of storage conditions on the phase composition of the studied cobalt-lanthanum catalyst precursor, caused by the formation of lanthanum hydroxide and lanthanum carbonates from La2O3 when contacting with air, was observed.

  6. High-Temperature Release of SO2 from Calcined Cement Raw Materials

    DEFF Research Database (Denmark)

    Nielsen, Anders Rooma; Larsen, Morten B.; Glarborg, Peter

    2011-01-01

    During combustion of alternative fuels in the material inlet end of cement rotary kilns, local reducing conditions may occur and cause reductive decomposition of sulfates from calcined cement raw materials. Decomposition of sulfates is problematic because it increases the gas-phase SO2...... concentration, which may cause deposit formation in the kiln system. In this study, the release of sulfur from calcined cement raw materials under both oxidizing and reducing conditions is investigated. The investigations include thermodynamic equilibrium calculations in the temperature interval of 800–1500 °C...... and experiments in a tube furnace reactor in the temperature interval of 900–1100 °C. The investigated conditions resemble actual conditions in the material inlet end of cement rotary kilns. It was found that the sulfates CaSO4, K2SO4, and Na2SO4 were all stable under oxidizing conditions but began to decompose...

  7. Conceptual design for remote handling methods using the HIP process in the Calcine Immobilization Program

    Energy Technology Data Exchange (ETDEWEB)

    Berry, S.M.; Cox, C.G.; Hoover, M.A.

    1994-03-01

    This report recommends the remote conceptual design philosophy for calcine immobilization using the hot isostatic press (HIP) process. Areas of remote handling operations discussed in this report include: (1) introducing the process can into the front end of the HIP process, (2) filling and compacting the calcine/frit mixture into the process can, (3) evacuating and sealing the process can, (4) non-destructive testing of the seal on the process can, (5) decontamination of the process can, (6) HIP furnace loading and unloading the process can for the HIPing operation, (7) loading an overpack canister with processed HIP cans, (8) sealing the canister, with associated non-destructive examination (NDE) and decontamination, and (9) handling canisters for interim storage at the Idaho Chemical Processing Plant (ICPP) located on the Idaho National Engineering Laboratory (INEL) site.

  8. Ce-doped titania nanoparticles: The effects of doped amount and calcination temperature on photocatalytic activity

    Science.gov (United States)

    Shi, Jianwen; Zou, Yajun; Ma, Dandan

    2017-01-01

    A series of Ce-doped TiO2 nanoparticles with different doped amount and calcination temperature were prepared by sol-gel method. These obtained samples were characterized with X-ray diffraction (XRD), transmission electron microscope (TEM) and ultraviolet-visible diffuse reflectance spectra (DRS), and their photocatalytic activities were evaluated by the photocatalytic degradation of methyl orange. Results showed that Ce doping inhibits the growth of crystal size and the phase transformation from anatase to rutile, leads to lattice distortion and expansion of TiO2. Furthermore, Ce doping brings the red-shift of absorption profile and the increase of photons absorption in the range of 400-600 nm. Photocatalytic degradation of methyl orange shows that Ce doping improves the photocatalytic activity of TiO2. The optimal doped amount is 0.05 mol% and the optimal calcined temperature is 600 °C for the maximum photocatalytic degradation efficiency in our experiment.

  9. EFFECT OF CALCINATION TEMPERATURE OF TUNISIAN CLAYS ON THE PROPERTIES OF GEOPOLYMERS

    Directory of Open Access Journals (Sweden)

    Essaidi N.

    2013-09-01

    Full Text Available Geopolymers are amorphous three dimensional aluminosilicate materials that may be synthesized at room or slightly higher temperature by alkaline activation of aluminosilicates obtained from industrial wastes, calcined clays and natural minerals. Among the different family of geopolymers, two Tunisian clays (a kaolinite clay from Tabarka and illito/kaolinitic clay from Medenine are tested for their feasibility of geopolymers at low temperature. The unfired and calcined clays were dissolved in strongly alkaline solution in order to produce consolidated materials whose pastes were characterized by their compressive strength. Hardened geopolymer samples were also submitted to X-Ray diffraction, FTIR spectroscopy and scanning electron microscopy analyses. The geopolymer strength is related to the structure and reactivity of the clay generated by thermal treatment and to the role of associated minerals in clays. The amorphous character of obtained geopolymers and the displacement of the IR wavenumber are signature of geopolymerisation reaction.

  10. Evaluation and selection of aqueous-based technology for partitioning radionuclides from ICPP calcine

    Energy Technology Data Exchange (ETDEWEB)

    Olson, A.L.; Schulz, W.W.; Burchfield, L.A.; Carlson, C.D.; Swanson, J.L.; Thompson, M.C.

    1993-02-01

    Early in 1993 Westinghouse Idaho Nuclear Company (WINCO) chartered a Panel of Nuclear Separations Experts. The purpose of this Panel was to assist WINCO scientists and engineers in selecting, evaluating, and ranking candidate aqueous-based processes and technologies for potential use in partitioning selected radionuclides from nitric acid solutions of retrieved Idaho Chemical Processing Plant (ICPP) calcine. Radionuclides of interest are all transuranium elements, {sup 90}Sr, {sup 99}Tc, {sup 129}I, and {sup 137}Cs. The six man Panel met for 4 days (February 16--19, 1993) on the campus of the Idaho State University in Pocatello, Idaho. Principal topics addressed included: Available radionuclide removal technology; applicability of separations technology and processes to ICPP calcine; and potential integrated radionuclide partitioning schemes. This report, prepared from contributions from all Panel members, presents a comprehensive account of the proceedings and significant findings of the February, 1993 meeting in Pocatello.

  11. Hydroxyapatite nanoparticles: electrospinning and calcination of hydroxyapatite/polyvinyl butyral nanofibers and growth kinetics.

    Science.gov (United States)

    Zakaria, Siti Maisurah; Sharif Zein, Sharif Hussein; Othman, Mohd Roslee; Jansen, John A

    2013-07-01

    Electrospinning of hydroxyapatite (HA)/polyvinyl butyral solution resulted in the formation of fibers with average diameter of 937-1440 nm. These fibers were converted into HA nanoparticles with size <100 nm after undergoing calcination treatment at 600°C. The diameter of the fiber was found to be influenced by applied voltage and spinning distance. The injection flowrate did not affect the diameter significantly. The electrospinning method successfully reduced the commercial HA particle size in the range of 400-1100 nm into <100 nm. The dispersion of the finally calcined HA nanoparticles was improved significantly after anionic sodium dodecyl sulfate surfactant was introduced. The experimental data of HA growth kinetics were subjected to the integral method of analysis, and the rate law of the reaction was found to follow the first order reaction. Copyright © 2012 Wiley Periodicals, Inc.

  12. Effect of Carbon Aggregates on the Properties of Carbon Refractories for a Blast Furnace

    Science.gov (United States)

    Chen, Xilai; Li, Yawei; Li, Yuanbing; Sang, Shaobai; Zhao, Lei; Li, Shujing; Jin, Shengli; Ge, Shan

    2010-04-01

    The effect of carbon aggregates on the carbon refractory properties for a blast furnace was studied with X-ray diffraction (XRD), scanning electron microscopy (SEM), an energy-dispersive X-ray, mercury porosimetry, a resistivity instrument, and a laser thermal conductivity meter. The results showed that the microporous structure of a sample was determined by the amount of β-SiC whiskers. The thermal conductivity was controlled by the thermal conductivity of the corresponding carbon aggregate, and the alkali and molten-iron attack was decided mainly by the pore and the graphitization degree of aggregate, respectively. For samples using calcined anthracites as aggregates, the microporous structure became worse, the thermal conductivity increased, and the molten-iron as well as the alkali attack became more severe with an increase in the anthracite calcining temperature. For all samples, microcrystalline graphite possessed the best microporous structure and the least alkali and molten-iron attack, whereas the graphite electrode scraps had the highest thermal conductivity and the most severe alkali and molten-iron attack.

  13. In-situ investigation of the calcination process of mixed oxide xerogels with Raman spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Panitz, J.C. [Paul Scherrer Inst. (PSI), Villigen (Switzerland)

    1997-06-01

    The controlled calcination of materials derived by sol-gel reactions is important for the evolution of the final structure. Raman spectroscopy is an ideal tool for the identification of surface species under in-situ conditions, as demonstrated in the following for the example of a molybdenum oxide-silica xerogel. Raman spectra of this particular sample were recorded at temperatures as high as 1173 K, and compared with those of a reference material.(author) 3 figs., 4 refs.

  14. Modeling of in-line low-NOx calciners - a parametric study

    DEFF Research Database (Denmark)

    Iliuta, Ion; Dam-Johansen, Kim; Jensen, Anker

    2002-01-01

    and NO emission. Carbon monoxide is a key component for the reduction of NO and reliable data for the kinetics of NO reduction by CO over CaO are very important for the prediction of the NO emission. The internal surface area of char and limestone particles influences the combustion and calcination rates...... and thereby the char and limestone conversion and the NO emission. (C) 2002 Elsevier Science Ltd. All rights reserved....

  15. Screw calciner mechanical direct denitration process for plutonium nitrate to oxide conversion

    Energy Technology Data Exchange (ETDEWEB)

    Souply, K. R.; Sperry, W. E.

    1977-10-14

    This report describes a screw calciner direct-denitration process for converting plutonium nitrate to plutonium oxide. The information should be used when making comparisons of alternative plutonium nitrate-to-oxide conversion processes or as a basis for further detailed studies. The report contains process flow sheets with a material balance; a process description; and a discussion of the process including history, advantages and disadvantages, and additional research required.

  16. Adsorption of basic chromium sulfate used in the tannery industries by calcined hydrotalcite

    Energy Technology Data Exchange (ETDEWEB)

    Lopez M, B. E.; Rivera R, R.; Iturbe G, J. L.; Olguin G, M. T., E-mail: beatriz.lopez@inin.gob.mx [ININ, Departamento de Quimica, Carretera Mexico-Toluca s/n, 52750 Ocoyoacac, Estado de Mexico (Mexico)

    2011-07-01

    The sorption behavior of the chemical species of Cr(III) from aqueous solutions by hydrotalcite calcined products was investigated considering the equilibrium ph (5.0 to 8.9) and the chromium concentration in aqueous solution (from 10.6 to 430.0 mmol/L) to obtain the corresponding isotherms. Each solution was prepared from basic Cr(III) sulphate which is a primary tanning agent used in the tannery industries. In this work no previous oxidation treatment was done to form Cr(vi) in order to remove the chromium from aqueous solutions by hydrotalcite. The amount of chromium in the remaining solutions after the sorption processes in a batch system by visible spectroscopy (Vis) was determined. The calcined hydrotalcite before and after the contact with the chromium(III) solutions by X-ray power diffraction, thermogravimetric analysis and Fourier transformed infrared spectroscopy, were characterized. The specific are by Brunauer, Emmett and Teller (Bet) method of each sample was also evaluated. It was found that under the experimental conditions of this work hydrolyzed species of Cr(III) are precipitated on the surface of the calcined hydrotalcite instead other adsorption mechanism, and the sulfate ions were the responsible to regenerated the crystalline structure of hydrotalcite, therefore the results are discussed in terms of both Cr(III) and sulfate chemical species. (Author)

  17. Effect of Calcination at Synthesis of Mg-Al Hydrotalcite Using co-Precipitation Method

    Directory of Open Access Journals (Sweden)

    Niar Kurnia Julianti

    2017-01-01

    Full Text Available The use of hydrotalcite in catalysis has wide attention in academic research and industrial parties. Based on its utilization, hydrotalcite can be active catalyst or support. This research is focused on the investigation of characteristic like spesific surface area of Mg-Al hydrotalcite which is prepared with different temperature of calcination. Synthesis of Mg-Al hydrotalcites with Mg/Al molar ratio 3:1 were prepared by co-precipitation method. Mg(NO33.6H2O and Al(NO33.9H2O as precursors of Mg-Al hydrotalcite. Na2CO3 was used as precipitant agent and NaOH was used as buffer solution. The solution was mixed and aging for 5 hours at 650oC. The dried precipitate was calcined at 2500oC, 3500oC, 4500oC, 5500oC and 6500oC. The characterization of functional group was determined by Fourier Transform Infra Red (FT-IR. The Identical peaks diffractogram were analyzed by X-Ray Diffraction (XRD. The spesific surface area was determined by adsorption-desorption of nitrogen. The largest surface area that obtained from the calcination temperature of 650oC is 156.252 m2/g.

  18. Calcination temperature effect on the microstructure and dielectric properties of M-type strontium hexagonal ferrites

    Science.gov (United States)

    Mohammed, J.; Sharma, Jyoti; Kumar, Sachin; Trudel, T. T. Carol; Srivastava, A. K.

    2017-07-01

    M-type hexagonal ferrites have found wide application in electronics industry due to the possibility of tuning properties such as dielectric properties. An improved dielectric property is useful in high frequency application. In this paper, we studied the effect of calcination temperature on structural and dielectric properties of Al-Mn substituted M-type strontium hexagonal ferrites with chemical composition Sr1-xAlxFe12-yMnyO19 (x=0.3 and y=0.6) synthesized by sol-gel auto-combustion method. The prepared sample was sintered at four different temperatures (T=750°C, 850°C, 950°C and 1050°C) for 5 hours. Characterisations of the synthesized samples were carried out using X-ray diffraction (XRD), impedance analyser, field emission electron microscope (FE-SEM) and energy dispersive X-ray (EDX) spectroscopy. The dielectric properties were explained on the basis of Koop's phenomenological theory and Maxwell Wagner theory. The sample calcinated at 750°C shows the highest value of dielectric constant and AC conductivity whereas that calcinated at 1050°C exhibit the lowest dielectric losses.

  19. Stabilization of As-, Pb-, and Cu-contaminated soil using calcined oyster shells and steel slag.

    Science.gov (United States)

    Moon, Deok Hyun; Wazne, Mahmoud; Cheong, Kyung Hoon; Chang, Yoon-Young; Baek, Kitae; Ok, Yong Sik; Park, Jeong-Hun

    2015-07-01

    In this study, As-, Pb-, and Cu-contaminated soil was stabilized using calcined oyster shells (COS) and steel slag (SS). The As-contaminated soil was obtained from a timber mill site where chromate copper arsenate (CCA) was used as a preservative. On the other hand, Pb- and Cu-contaminated soil was obtained from a firing range. These two soils were thoroughly mixed to represent As-, Pb-, and Cu-contaminated soil. Calcined oyster shells were obtained by treating waste oyster shells at a high temperature using the calcination process. The effectiveness of stabilization was evaluated by 1-N HCl extraction for As and 0.1-N HCl extraction for Pb and Cu. The treatment results showed that As, Pb, and Cu leachability were significantly reduced upon the combination treatment of COS and SS. The sole treatment of SS (10 wt%) did not show effective stabilization. However, the combination treatment of COS and SS showed a significant reduction in As, Pb, and Cu leachability. The best stabilization results were obtained from the combination treatment of 15 wt% COS and 10 wt% SS. The SEM-EDX results suggested that the effective stabilization of As was most probably achieved by the formation of Ca-As and Fe-As precipitates. In the case of Pb and Cu, stabilization was most probably associated with the formation of pozzolanic reaction products such as CSHs and CAHs.

  20. Numerical study of co-firing pulverized coal and biomass inside a cement calciner.

    Science.gov (United States)

    Mikulčić, Hrvoje; von Berg, Eberhard; Vujanović, Milan; Duić, Neven

    2014-07-01

    The use of waste wood biomass as fuel is increasingly gaining significance in the cement industry. The combustion of biomass and particularly co-firing of biomass and coal in existing pulverized-fuel burners still faces significant challenges. One possibility for the ex ante control and investigation of the co-firing process are computational fluid dynamics (CFD) simulations. The purpose of this paper is to present a numerical analysis of co-firing pulverized coal and biomass in a cement calciner. Numerical models of pulverized coal and biomass combustion were developed and implemented into a commercial CFD code FIRE, which was then used for the analysis. Three-dimensional geometry of a real industrial cement calciner was used for the analysis. Three different co-firing cases were analysed. The results obtained from this study can be used for assessing different co-firing cases, and for improving the understanding of the co-firing process inside the calculated calciner. © The Author(s) 2014.

  1. Defluoridation of groundwater by calcined Mg/Al layered double hydroxide

    Directory of Open Access Journals (Sweden)

    A. Elhalil

    2016-03-01

    Full Text Available The present study evaluated calcined Mg/Al layered double hydroxide (CLDH availability for the removal of fluoride from local groundwaters. The Mg/Al layered double hydroxide (LDH was synthesized by co-precipitation method and characterized by XRD, FT-IR and TGA-TDA analyses. Batch defluoridation experiments were performed under various conditions such as calcination, solution pH, contact time, temperature, material dosage and reuse. Experimental results indicate that fluoride removal strongly increased after calcination of the LDH up to 600 °C. The maximum fluoride removal was obtained at solution pH of 6.85. Kinetics of fluoride removal followed the pseudo-second order kinetic model. The rise in solution temperature strongly enhances the removal efficiency. The adsorption mechanism involved surface adsorption, ion exchange interaction and original LDH structure reconstruction by rehydration of mixed metal oxides and concomitant intercalation of fluoride ions into the interlayer region. The optimum dosages required to meet the national standard for drinking water quality were found to be 0.29 and 0.8 g/L, respectively, for Bejaad and Settat goundwaters. A decrease in the fluoride uptake with increasing the number of regeneration cycles was observed.

  2. Study on Al2O3 extraction from activated coal gangue under different calcination atmospheres

    Science.gov (United States)

    Dong, Ling; Liang, Xinxing; Song, Qiang; Gao, Gewu; Song, Lihua; Shu, Yuanfeng; Shu, Xinqian

    2017-12-01

    Coal gangue was calcinated under air, nitrogen, carbon dioxide, air-hydrogen, and hydrogen atmospheres. The effects of different calcination temperatures and atmospheres on the mineral composition of activated coal gangue were investigated by X-ray diffraction. Moreover, the acid leaching kinetics of aluminum oxide from coal gangue was investigated with sulfuric acid. It showed that the air atmosphere promoted kaolinite decomposition during coal gangue calcination. The hydrogen atmosphere promoted the activation and decomposition of kaolinite at reaction temperatures exceeding 650°C. The carbon dioxide atmosphere eliminated the influence of residual carbon on coal gangue. When the ratio of acid/coal gangue was 1.5 and reaction temperature was 650°C, the sulfuric acid leaching rate under air, air-hydrogen, carbon dioxide, hydrogen and nitrogen atmospheres were 93.66%, 90.90%, 84.06%, 81.91% and 77.54% respectively. The acid leaching reaction process conformed to unreacted shrinking core model of particle unchanged, and was controlled by the interfacial chemical reaction. The reaction kinetic equation for the leaching process was 1-(1-x)1/3=kt with an apparent activation energy of 48.97 kJ/mol.

  3. Improvement of Gold Leaching from a Refractory Gold Concentrate Calcine by Separate Pretreatment of Coarse and Fine Size Fractions

    National Research Council Canada - National Science Library

    Qian Li; Yan Zhang; Xiaoliang Liu; Bin Xu; Yongbin Yang; Tao Jiang

    2017-01-01

    A total gold extraction of 70.2% could only be reached via direct cyanidation from a refractory As-, S- and C-bearing gold concentrate calcine, and the gold extraction varied noticeably with different size fractions...

  4. Aggregated Computational Toxicology Online Resource

    Data.gov (United States)

    U.S. Environmental Protection Agency — Aggregated Computational Toxicology Online Resource (AcTOR) is EPA's online aggregator of all the public sources of chemical toxicity data. ACToR aggregates data...

  5. Chemical and mineralogical modifications of simplified radioactive waste calcine during heat treatment

    Energy Technology Data Exchange (ETDEWEB)

    Monteiro, A. [CEA, DEN, DTCD/SECM/LDMC Marcoule, BP 17171, F-30207 Bagnols-sur-Cèze cedex (France); Schuller, S., E-mail: sophie.schuller@cea.fr [CEA, DEN, DTCD/SECM/LDMC Marcoule, BP 17171, F-30207 Bagnols-sur-Cèze cedex (France); Toplis, M.J. [CNRS, Observatoire Midi Pyrénées, IRAP (UMR 5277), F-31400 Toulouse (France); Podor, R.; Ravaux, J.; Clavier, N.; Brau, H.P. [ICSM UMR 5257 CEA/CNRS/UMR/ENSCM Site de Marcoule, BP 17171, F-30207 Bagnols-sur-Cèze cedex (France); Charpentier, T. [UMR CEA/CNRS 3299, IRAMIS, SIS2M, LSDRM Saclay, F-91191 Gif-sur-Yvette cedex (France); Angeli, F. [CEA, DEN, DTCD/SECM/LCLT Marcoule, BP 17171, F-30207 Bagnols-sur-Cèze cedex (France); Leterrier, N. [CEA, DEN, DM2S/SFME/LSFT Saclay, F-91191 Gif-sur-Yvette cedex (France)

    2014-05-01

    The microstructural and mineralogical changes associated with heating calcined mixtures of Al(NO{sub 3}){sub 3}⋅9H{sub 2}O–NaNO{sub 3} have been studied. This system is a simplified analogue of high-level radioactive waste calcine, one of the raw materials used in the vitrification process employed for waste management. The decomposition (dehydration and denitration) and formation of secondary crystalline phases have been studied by differential thermal and gravimetric analysis (DTA and TGA), and heat-treated products characterized by X-ray diffraction, Raman spectroscopy, Nuclear Magnetic Resonance (NMR) and Transmission Electron Microscopy (TEM). It is found that pure Al(NO{sub 3}){sub 3}⋅9H{sub 2}O transforms to amorphous Al{sub 2}O{sub 3} at a temperature of ∼180 °C, well below that of the calcination process (500 °C). This amorphous Al{sub 2}O{sub 3} is highly porous with a high specific surface area, but may in turn convert to denser γ-Al{sub 2}O{sub 3} and α-Al{sub 2}O{sub 3} with increasing temperature. On the other hand, pure NaNO{sub 3} remains stable up to ∼880 °C, despite a solid–liquid transition at ∼320 °C. For Al(NO{sub 3}){sub 3}⋅9H{sub 2}O–NaNO{sub 3} mixtures, the products of calcination at 500 °C are found to consist of very fine porous material containing Na, Al and O, in addition to a variable proportion of well-defined crystals consisting of Na, and O. Heating these mixtures to temperatures of up to 1000 °C shows that for the case 80% Al(NO{sub 3}){sub 3}⋅9H{sub 2}O −20% NaNO{sub 3} (weight%) a variety of crystalline sodium aluminates is formed (NaAlO{sub 2}, NaAl{sub 11}O{sub 17}, NaAl{sub 6}O{sub 9.5}), while for the 50–50 mixture, only NaAlO{sub 2} is found. In large amounts, addition of alumina thus leads to the formation of crystalline phases rich in Al{sub 2}O{sub 3} that are responsible for hardening the calcine as the temperature rises. The kinetics of nitrogen loss from NaNO{sub 3} are also found to be

  6. Recycled aggregates concrete: aggregate and mix properties

    Directory of Open Access Journals (Sweden)

    González-Fonteboa, B.

    2005-09-01

    Full Text Available This study of structural concrete made with recycled concrete aggregate focuses on two issues: 1. The characterization of such aggregate on the Spanish market. This involved conducting standard tests to determine density, water absorption, grading, shape, flakiness and hardness. The results obtained show that, despite the considerable differences with respect to density and water absorption between these and natural aggregates, on the whole recycled aggregate is apt for use in concrete production. 2. Testing to determine the values of basic concrete properties: mix design parameters were established for structural concrete in non-aggressive environments. These parameters were used to produce conventional concrete, and then adjusted to manufacture recycled concrete aggregate (RCA concrete, in which 50% of the coarse aggregate was replaced by the recycled material. Tests were conducted to determine the physical (density of the fresh and hardened material, water absorption and mechanical (compressive strength, splitting tensile strength and modulus of elasticity properties. The results showed that, from the standpoint of its physical and mechanical properties, concrete in which RCA accounted for 50% of the coarse aggregate compared favourably to conventional concrete.

    Se aborda el estudio de hormigones estructurales fabricados con áridos reciclados procedentes de hormigón, incidiéndose en dos aspectos: 1. Caracterización de tales áridos, procedentes del mercado español. Para ello se llevan a cabo ensayos de densidad, absorción, granulometría, coeficiente de forma, índice de lajas y dureza. Los resultados obtenidos han puesto de manifiesto que, a pesar de que existen diferencias notables (sobre todo en cuanto a densidad y absorción con los áridos naturales, las características de los áridos hacen posible la fabricación de hormigones. 2. Ensayos sobre propiedades básicas de los hormigones: se establecen parámetros de dosificaci

  7. Protein Colloidal Aggregation Project

    Science.gov (United States)

    Oliva-Buisson, Yvette J. (Compiler)

    2014-01-01

    To investigate the pathways and kinetics of protein aggregation to allow accurate predictive modeling of the process and evaluation of potential inhibitors to prevalent diseases including cataract formation, chronic traumatic encephalopathy, Alzheimer's Disease, Parkinson's Disease and others.

  8. Effect of calcination temperature on structural properties and photocatalytic activity of Mn-C-codoped TiO{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Cai, Jianbo; Xin, Wei; Liu, Guanglong; Lin, Die; Zhu, Duanwei, E-mail: liugl@mail.hzau.edu.cn [Laboratory of Eco-Environmental Engineering Research, College of Resources and Environment, Huazhong Agricultural University (HZAU), Wuhan (China)

    2016-03-15

    Mn-C-codoped TiO{sub 2} catalysts were synthesized by modified sol-gel method based on the self-assembly technique using polyoxyethylene sorbitan monooleate (Tween 80) as template and carbon precursor and the effect of calcination temperature on their structural properties and photocatalytic activity were investigated. The XRD results showed undoped and Mn-C-codoped TiO{sub 2} calcined at 400 deg C only include anatase phase and the rutile phase appears when the calcination temperature reached to 600 deg C. UV-vis absorption spectroscopy demonstrates that the absorption spectra are strongly modified by the calcination temperature. Moreover, the Mn-C-TiO{sub 2} calcined at 400 deg C showed the lowest PL intensity due to a decrease in the recombination rate of photogenerated electrons and holes under light irradiation. The photocatalytic activity of Mn-C-codoped TiO{sub 2} were evaluated by the degradation of methyl orange (MO) under the simulate daylight irradiation and all the prepared Mn-C-codoped TiO{sub 2} samples exhibited high photocatalytic activities for photocatalytic decolorisation of methyl orange aqueous solution. At 400 deg C, the Mn-C-codoped TiO{sub 2} samples showed the highest photocatalytic activity due to synergetic effects of good crystallize ation, appropriate phase composition and slower recombination rate of photogenerated charge carriers, which further confirms the calcination temperature could affect the properties of Mn-C-codoped TiO2 significantly. (author)

  9. Role of Calcination Temperature on the Hydrotalcite Derived MgO–Al2O3 in Converting Ethanol to Butanol

    Energy Technology Data Exchange (ETDEWEB)

    Ramasamy, Karthikeyan K.; Gray, Michel J.; Job, Heather M.; Santosa, Daniel M.; Li, Xiaohong S.; Devaraj, Arun; Karkamkar, Abhijeet J.; Wang, Yong

    2015-10-09

    In the base catalyzed ethanol condensation reactions, the calcined MgO-Al2O3 derived hydrotalcites used broadly as catalytic material and the calcination temperature plays a big role in determining the catalytic activity. The characteristic of the hydrotalcite material treated between catalytically relevant temperatures 450ºC and 800ºC have been studied with respect to the physical, chemical, and structural properties and compared with catalytic activity testing. With the increasing calcination temperature, the total measured catalytic basicity dropped linearly with the calcination temperature and the total measured acidity stayed the same for all the calcination temperatures except 800ºC. However, the catalyst activity testing does not show any direct correlation between the measured catalytic basicity and the catalyst activity to the ethanol condensation reaction to form 1-butanol. The highest ethanol conversion of 44 percent with 1-butanol selectivity of 50 percent was achieved for the 600ºC calcined hydrotalcite material.

  10. Aggregation of retail stores

    Science.gov (United States)

    Jensen, Pablo; Boisson, Jean; Larralde, Hernán

    2005-06-01

    We propose a simple model to understand the economic factors that induce aggregation of some businesses over small geographical regions. The model incorporates price competition with neighboring stores, transportation costs and the satisfaction probability of finding the desired product. We show that aggregation is more likely for stores selling expensive products and/or stores carrying only a fraction of the business variety. We illustrate our model with empirical data collected in the city of Lyon.

  11. Observing Convective Aggregation

    Science.gov (United States)

    Holloway, Christopher E.; Wing, Allison A.; Bony, Sandrine; Muller, Caroline; Masunaga, Hirohiko; L'Ecuyer, Tristan S.; Turner, David D.; Zuidema, Paquita

    2017-11-01

    Convective self-aggregation, the spontaneous organization of initially scattered convection into isolated convective clusters despite spatially homogeneous boundary conditions and forcing, was first recognized and studied in idealized numerical simulations. While there is a rich history of observational work on convective clustering and organization, there have been only a few studies that have analyzed observations to look specifically for processes related to self-aggregation in models. Here we review observational work in both of these categories and motivate the need for more of this work. We acknowledge that self-aggregation may appear to be far-removed from observed convective organization in terms of time scales, initial conditions, initiation processes, and mean state extremes, but we argue that these differences vary greatly across the diverse range of model simulations in the literature and that these comparisons are already offering important insights into real tropical phenomena. Some preliminary new findings are presented, including results showing that a self-aggregation simulation with square geometry has too broad distribution of humidity and is too dry in the driest regions when compared with radiosonde records from Nauru, while an elongated channel simulation has realistic representations of atmospheric humidity and its variability. We discuss recent work increasing our understanding of how organized convection and climate change may interact, and how model discrepancies related to this question are prompting interest in observational comparisons. We also propose possible future directions for observational work related to convective aggregation, including novel satellite approaches and a ground-based observational network.

  12. Observing Convective Aggregation

    Science.gov (United States)

    Holloway, Christopher E.; Wing, Allison A.; Bony, Sandrine; Muller, Caroline; Masunaga, Hirohiko; L'Ecuyer, Tristan S.; Turner, David D.; Zuidema, Paquita

    2017-06-01

    Convective self-aggregation, the spontaneous organization of initially scattered convection into isolated convective clusters despite spatially homogeneous boundary conditions and forcing, was first recognized and studied in idealized numerical simulations. While there is a rich history of observational work on convective clustering and organization, there have been only a few studies that have analyzed observations to look specifically for processes related to self-aggregation in models. Here we review observational work in both of these categories and motivate the need for more of this work. We acknowledge that self-aggregation may appear to be far-removed from observed convective organization in terms of time scales, initial conditions, initiation processes, and mean state extremes, but we argue that these differences vary greatly across the diverse range of model simulations in the literature and that these comparisons are already offering important insights into real tropical phenomena. Some preliminary new findings are presented, including results showing that a self-aggregation simulation with square geometry has too broad distribution of humidity and is too dry in the driest regions when compared with radiosonde records from Nauru, while an elongated channel simulation has realistic representations of atmospheric humidity and its variability. We discuss recent work increasing our understanding of how organized convection and climate change may interact, and how model discrepancies related to this question are prompting interest in observational comparisons. We also propose possible future directions for observational work related to convective aggregation, including novel satellite approaches and a ground-based observational network.

  13. PREPARATION AND PROPERTIES OF Co-Fe MIXED OXIDES OBTAINED BY CALCINATION OF LAYERED DOUBLE HYDROXIDES

    Directory of Open Access Journals (Sweden)

    M. E. Pérez Bernal

    2004-12-01

    Full Text Available Solids containing Co(II and Fe(III with molar ratios of 2/1, 3/2, 1/1, 2/3 and 1/2 have been synthetised by coprecipitation at constant pH. All they displayed a hydrotalcite-like structure with interlayer carbonate, which crystallinity decreases as the iron content was increased. No other crystalline phase was identified, even in the Fe-rich samples. They have been characterised by powder X-ray diffraction, FT-IR spectroscopy, thermal analysis (differential thermal analysis, thermogravimetric analysis and temperature-programmed reduction, in addition to specific surface area assessment by nitrogen adsorption at -196°C. A minor oxidation of Co(II to Co(III is observed in the Co-rich samples, although it reverses again to Co(II upon calcination in oxygen at ca. 850°C. Thermal decomposition takes place in a single step up to ca. 350°C, and the specific surface area increases with the iron content, probably because of the presence of hydrated amorphous iron oxides. The solids calcined at 1200°C in air contain crystalline CoO, Co3O4 and CoFe2O4 (spinel, this one being the dominant phase, and only phase detected for large Fe contents. Metallic species are more easily reduced in the original solids than in the calcined ones, and in all cases iron seems to be reduced at a higher temperature than cobalt.

  14. Phosphate interaction with calcined form of Mg-Al-CO3 hydrotalcite in aqueous solutions

    OpenAIRE

    Kostura, Bruno; Matýsek, Dalibor; Kukutschová, Jana; Leško, Juraj

    2012-01-01

    In this study the sorption removal of phosphates from aqueous solutions was investigated. The sorbent used was Mg-Al-CO3 hydrotalcite with a molar ratio of 2:1 calcined at 450 oC. The retention capacity of cLDH was 2.88 mmol P/g. The sorption can be characterized by a kinetic model of the pseudo-second order. Laboratory tests proved the existence of two steps – fast and slow. The fast step is associated with regeneration of the layered structure accompanied by surface adsorption of phosphates...

  15. Large scale production of SrFe12O19 nanoparticles with low calcination temperature

    Science.gov (United States)

    Kumar, M. Rajesh; Yu, Z. J.; Pan, Q.

    2017-09-01

    High quality SrFe12O19 nanoparticles were successfully synthesized by a co-precipitation method with low calcination temperature. Structural, morphological and magnetic properties of SrFe12O19 nanoparticles were investigated by means of x-ray diffraction (XRD), Fourier transform infrared spectra (FT-IR), scanning electron microscopy (SEM), and vibrating sample magnetometer (VSM) analysis. The formation of SrFe12O19 nanoparticles were confirmed by XRD analysis. The actual size and morphology of the nanoparticles were characterized by SEM.

  16. Development of a SREX Flowsheet for the Separation of Strontium from Dissolved INEEL Zirconium Calcine

    Energy Technology Data Exchange (ETDEWEB)

    Law, Jack Douglas; Wood, David James; Todd, Terry Allen

    1999-02-01

    Laboratory experimentation has indicated that the SREX process is effective for partitioning 90 Sr from acidic radioactive waste solutions located at the Idaho Nuclear Technology and Engineering Center. These laboratory results were used to develop a flowsheet for countercurrent testing of the SREX process with dissolved pilot plant calcine. Testing was performed using 24 stages of 2-cm diameter centrifugal contactors which are installed in the Remote Analytical Laboratory hot cell. Dissolved Run #64 pilot plant calcine spiked with 85 Sr was used as feed solution for the testing. The flowsheet tested consisted of an extraction section (0.15 M 4',4'(5')-di-(tert-butylcyclohexo)-18-crown-6 and 1.5 M TBP in Isopar-L.), a 1.0 M NaNO3 scrub section to remove extracted K from the SREX solvent, a 0.01 M HNO3 strip section for the removal of Sr from the SREX solvent, a 0.25 M Na2CO3 wash section to remove degradation products from the solvent, and a 0.1 M HNO3 rinse section. The behavior of 85 Sr, Na, K, Al, B, Ca, Cr, Fe, Ni, and Zr was evaluated. The described flowsheet successfully extracted 85 Sr from the dissolved pilot plant calcine with a removal efficiency of 99.6%. Distribution coefficients for 85 Sr ranged from 3.6 to 4.5 in the extraction section. With these distribution coefficients a removal efficiency of approximately >99.99% was expected. It was determined that the lower than expected removal efficiency can be attributed to a stage efficiency of only 60% in the extraction section. Extracted K was effectively scrubbed from the SREX solvent with the 1.0 M NaNO3 resulting in only 6.4% of the K in the HLW strip product. Sodium was not extracted from the dissolved calcine by the SREX solvent; however, the use of a 1.0 M NaNO3 scrub solution resulted in a Na concentration of 70 mg/L (12.3% of the feed concentration) in the HLW strip product. Al, B, Ca, Cr, Fe, Ni, and Zr were determined to be essentially inextractable.

  17. Development of a SREX flowsheet for the separation of strontium from dissolved INEEL zirconium calcine

    Energy Technology Data Exchange (ETDEWEB)

    Law, J.D.; Wood, D.J.; Todd, T.A.

    1999-01-01

    Laboratory experimentation has indicated that the SREX process is effective for partitioning {sup 90}Sr from acidic radioactive waste solutions located at the Idaho Nuclear Technology and Engineering Center. These laboratory results were used to develop a flowsheet for countercurrent testing of the SREX process with dissolved pilot plant calcine. Testing was performed using 24 stages of 2-cm diameter centrifugal contactors which are installed in the Remote Analytical Laboratory hot cell. Dissolved Run No.64 pilot plant calcine spiked with {sup 85}Sr was used as feed solution for the testing. The flowsheet tested consisted of an extraction section (0.15 M 4{prime},4{prime}(5{prime})-di-(tert-butylcyclohexo)-18-crown-6 and 1.5 M TBP in Isopar-L.), a 1.0 M NaNO{sub 3} scrub section to remove extracted K from the SREX solvent, a 0.01 M HNO{sub 3} strip section for the removal of Sr from the SREX solvent, a 0.25 M Na2CO{sub 3} wash section to remove degradation products from the solvent, and a 0.1 M HNO{sub 3} rinse section. The behavior of {sup 85}Sr, Na, K, Al, B, Ca, Cr, Fe, Ni, and Zr was evaluated. The described flowsheet successfully extracted {sup 85}Sr from the dissolved pilot plant calcine with a removal efficiency of 99.6%. Distribution coefficients for {sup 85}Sr ranged from 3.6 to 4.5 in the extraction section. With these distribution coefficients a removal efficiency of approximately >99.99% was expected. It was determined that the lower than expected removal efficiency can be attributed to a stage efficiency of only 60% in the extraction section. Extracted K was effectively scrubbed from the SREX solvent with the 1.0 M NaNO{sub 3} resulting in only 6.4% of the K in the HLW strip product. Sodium was not extracted from the dissolved calcine by the SREX solvent; however, the use of a 1.0 M NaNO{sub 3} scrub solution resulted in a Na concentration of 70 mg/L (12.3% of the feed concentration) in the HLW strip product. Al, B, Ca, Cr, Fe, Ni, and Zr were

  18. Quantifying Dictyostelium discoideum Aggregation

    Science.gov (United States)

    McCann, Colin; Kriebel, Paul; Parent, Carole; Losert, Wolfgang

    2008-03-01

    Upon nutrient deprivation, the social amoebae Dictyostelium discoideum enter a developmental program causing them to aggregate into multicellular organisms. During this process cells sense and secrete chemical signals, often moving in a head-to-tail fashion called a `stream' as they assemble into larger entities. We measure Dictyostelium speed, shape, and directionality, both inside and outside of streams, and develop methods to distinguish group dynamics from behavior of individual cells. We observe an overall increase in speed during aggregation and a decrease in speed fluctuations once a cell joins a stream. Initial results indicate that when cells are in close proximity the trailing cells migrate specifically toward the backs of leading cells.

  19. Idaho National Engineering and Environmental Laboratory, Old Waste Calcining Facility, Scoville vicinity, Butte County, Idaho -- Photographs, written historical and descriptive data. Historical American engineering record

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1997-12-31

    This report describes the history of the Old Waste Calcining Facility. It begins with introductory material on the Idaho National Engineering and Environmental Laboratory, the Materials Testing Reactor fuel cycle, and the Idaho Chemical Processing Plant. The report then describes management of the wastes from the processing plant in the following chapters: Converting liquid to solid wastes; Fluidized bed waste calcining process and the Waste Calcining Facility; Waste calcining campaigns; WCF gets a new source of heat; New Waste Calcining Facility; Last campaign; Deactivation and the RCRA cap; Significance/context of the old WCF. Appendices contain a photo key map for HAER photos, a vicinity map and neighborhood of the WCF, detailed description of the calcining process, and chronology of WCF campaigns.

  20. Preparation of Nanosized LaCoO3 through Calcination of a Hydrothermally Synthesized Precursor

    Directory of Open Access Journals (Sweden)

    L. Tepech-Carrillo

    2016-01-01

    Full Text Available A method for obtaining nanosized LaCoO3 crystals from calcination of a precursor powder synthesized by a hydrothermal route is reported. Details concerning the evolution of the microstructure and formation mechanism of the perovskite phase were studied by powder X-ray diffraction, scanning electron microscopy, energy dispersive X-ray spectroscopy, Raman spectroscopy, and thermal analysis. It was found that the morphology of the sample progressively turns from a mix of fibers and rods to interconnected nanocrystals. It is determined that LaCoO3 phase is produced by a reaction of cobalt and lanthanum oxides, the latter produced by a two-step dehydration process of La(OH3. Finally, it was found that nearly stoichiometric LaCoO3 nanocrystals can be obtained at temperatures as low as 850°C. Nevertheless, whether higher calcination temperatures are used, appropriate reaction times and a controlled atmosphere are required in order to avoid formation of lanthanum carbonates and high density of lattice defects.

  1. Uptake of chloride ion from aqueous solution by calcined layered double hydroxides: equilibrium and kinetic studies.

    Science.gov (United States)

    Lv, Liang; He, Jing; Wei, Min; Evans, D G; Duan, Xue

    2006-02-01

    Layered double hydroxides (LDH) calcined within a certain temperature range (denoted as CLDH) have been shown to recover their original layered structure in the presence of appropriate anions. In the light of this so-called "memory effect", uptake of chloride ion from aqueous solution by calcined MgAl-CO3 LDH was investigated in batch mode. The equilibrium isotherm showed that the uptake of chloride ion by CLDH was consistent with the Langmuir and Freundlich equations and that the Langmuir model gave a better fit to the experimental data than the Freundlich model. The maximum uptake capacity of CLDH for chloride ion was 149.5 mg/g, close to the stoichiometric uptake (168 mg/g). The influence of varying pH of solution, initial chloride concentration, adsorbent quantity, and temperature on the kinetics of chloride removal has also been explored. Four kinetic models were used to fit the experimental data, and it was found that the pseudo-second-order kinetics model could be used to describe the uptake process satisfactorily. The calculated value of Ea was found to be 56.8 kJ/mol, which suggests that the process of uptake of chloride ion is controlled by the rate of reaction of chloride ion with the CLDH rather than diffusion. A mechanism for removal of chloride ion has been confirmed by X-ray diffraction, FT-IR spectroscopy and TG-MS measurements.

  2. Effects of Composition and Calcination Temperature on Photocatalytic Evolution over from Glycerol and Water Mixture

    Directory of Open Access Journals (Sweden)

    Cancan Fan

    2012-01-01

    Full Text Available A series of sulfide coupled semiconductors supported on SiO2, (, was prepared by incipient wet impregnation method. The photocatalysts were characterized by XRD, XPS, TPR, and UV/Vis DRS. Characterization results show that the chemical actions between ZnS and CdS resulted in the formation of solid solutions on the surface of the support and the formation of them is affected by the molar ratio of ZnS/CdS and calcination temperature. Performance of photocatalysts was tested in the home made reactor under both UV light and solar-simulated light irradiation by detecting the rate of the photocatalytic H2 evolution from glycerol solution. The hydrogen production rates are related to the catalyst composition, surface structure, photoabsorption property, as well as the amount of solid solution. The maximum rate of hydrogen production, 550 μmol·h−1 under UV light irradiation and 210 μmol·h−1 under solar-simulated light irradiation, was obtained over Cd0.8Zn0.2S/SiO2 solid solution calcined at 723 K.

  3. Evaluation of calcination temperature and phase composition ratio for new hyroxyapatite

    Science.gov (United States)

    Salimi, M. N. Ahmad; Chin, H. S.

    2017-10-01

    The demand of production of hydroxyapatite (HA) has been increasing for the purpose of medical and dental application. HA possesses the excellent properties leads to the priority choice for ceramic bone replacement. Synthesis route by wet chemical precipitation is commonly practised in industrial scale. Calcium hydroxide and Orthophosphoric acid are the precursors for production scale. The synthesis of HA is conducted by varying the synthetic condition: stirring rate, calcium-phosphate and calcination temperature. This paper is focused on the properties of HA produced by regulating the synthetic condition so that the qualities of HA can be well performed. Characterization studies were also carried out by Fourier Transform Infrared Spectroscopy (FT-IR) for functional group identification, Scanning Electron Microscope (SEM) for surface morphology analysis and X-Ray Diffraction (XRD) for phase composition and crystallinity respectively. Narrow particle size distribution contributed to better quality of hydroxyapatite for bone replacement. Both calcium-phosphate ratio and calcination temperature would affect the phase composition of calcium phosphate.

  4. Preparation of mesoporous MgO: phenomena occurred during the calcination

    Science.gov (United States)

    Thanh Huyen, Pham; Callone, Emanuela; Campostrini, Renzo; Carturan, Giovanni; Thi Hong, Tran; Nhat, Hoang Nam; Dang Chinh, Huynh

    2013-10-01

    Mesoporous MgO has been synthesized in the presence of the neutral block co-polymer surfactant Pluronic F127. The characterization of synthesized material was carried out by mean of X-ray diffraction (XRD), scanning electron microscope (SEM) and Brunauer-Emmett-Teller technique (BET). The obtained MgO exhibited a value of the surface area of 157 m2/g and showed a narrow pore size distribution centered at 4.3 nm. The phenomena and gas evolved during calcinations have been investigated by thermogravimeter-mass spectrometer (TG-MS). During the calcinations, the precursor Mg(OH)2 was converted to MgO with a mass loss of 29% and with the formation of H2O (>60% of the gas evolved). The desorption of CO2 and a small amount of CO and/or N2 which were adsorbed from air on the surface of Mg(OH)2 were also observed. No organic compounds were found which indicated that F127 was completely removed by Soxhlet extraction.

  5. Calcined Solution-Based PVP Influence on ZnO Semiconductor Nanoparticle Properties

    Directory of Open Access Journals (Sweden)

    Halimah Mohamed Kamari

    2017-02-01

    Full Text Available A water-based solution of polyvinylpyrrolidone (PVP at various concentrations and zinc nitrates were used in conjunction with calcination to produce zinc oxide semiconductor nanoparticles. The extent to which the zinc oxide semiconductor nanoparticles had become crystallized was measured using X-ray diffraction (XRD, whilst morphological characteristics were determined using scanning electron microscopy (SEM. Transmission electron microscopy (TEM supported by XRD results were used to evaluate the average particle size. Fourier transform infrared spectroscopy (FT-IR was then carried out in order to identify the composition phase, since this suggested that the samples contained metal oxide bands and that all organic compounds had been effectively removed after calcination. A UV-VIS spectrophotometer was used to determine the energy band gap and illustrate optical features. Additionally, photoluminescence (PL spectra revealed that the intensity of photoluminescence decreased with a decrease in particle size. The obtained results have mainly been inclusive for uses by several semiconductor applications in different fields, such as environmental applications and studies, since an absorption process for energy wavelengths could efficiently occur.

  6. Implementation of industrial waste ferrochrome slag in conventional and low cement castables: Effect of calcined alumina

    Directory of Open Access Journals (Sweden)

    Pattem Hemanth Kumar

    2014-12-01

    Full Text Available A new class of conventional and low-cement ferrochrome slag-based castables were prepared from 40 wt.% ferrochrome slag and 45 wt.% calcined bauxite. Rest fraction varied between high alumina cement (HAC acting as hydraulic binder and calcined alumina as pore filling additive. Standard ASTM size briquettes were prepared for crushing and bending strengths evaluation, and the samples were then subjected to firing at 800, 1100 and 1300 °C for a soaking period of 3 h. The microstructure and refractory properties of the prepared castables have been investigated using X-ray diffraction (XRD, scanning electron microscopy (SEM, cold crushing strength, modulus of rupture and permanent linear changes (PLCs test. Castables show good volume stability (linear change <0.7% at 1300 °C. The outcomes of these investigations were efficacious and in accordance with previously reported data of similar compositions. High thermo-mechanical and physico-chemical properties were attained pointing out an outstanding potential to increase the refractory lining working life of non-recovery coke oven and reheating furnaces.

  7. Calcination temperature influenced multiferroic properties of Ca-doped BiFeO{sub 3} nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Dhir, Gitanjali, E-mail: gitanjali.thaprian@gmail.com; Uniyal, Poonam; Verma, N. K. [Nano Research Lab, School of Physics and Materials Science, Thapar University, Patiala-147004 (India)

    2015-06-24

    The influence of Ca-doping and particle size on structural, morphological and magnetic properties of BiFeO{sub 3} nanoparticles has been studied. A sol-gel method was employed for the synthesis of nanoparticles and their particle size was tailored by varying the calcination temperature. Structural analysis revealed a rhombohedral distortion induced by Ca-substitution. The broadening of diffraction peaks with decreasing calcination temperature was indicative of reduction in crystallite size. The morphological analysis revealed the formation of agglomerated nanoparticles having average particle size ranging from 10-15 and 50-55 nm for C4 and C6, respectively. The agglomeration is attributed to high surface energy of nanoparticles. Ferromagnetism has been displayed by all the synthesized nanoparticles. Enhancement of saturation magnetization with Ca-substitution is attributed to suppression of spin cycloid structure by the reduction in size, lattice distortion and creation of oxygen vacancies by the substitution of divalent ion at trivalent site. Further, this value increases as a function of decreasing particle size. Strong particle size effects on magnetic properties of the synthesized nanoparticles are owed to increasing surface to volume ratio. All these observations are indicative of strong dependence of multiferroism on particle size.

  8. Easily recycled Bi2O3 photocatalyst coatings prepared via ball milling followed by calcination

    Science.gov (United States)

    Cheng, Lijun; Hu, Xumin; Hao, Liang

    2017-06-01

    Bi2O3 photocatalyst coatings derived from Bi coatings were first prepared by a two-step method, namely ball milling followed by the calcination process. The as-prepared samples were characterized by XRD, SEM, XPS and UV-Vis spectra, respectively. The results showed that monoclinic Bi2O3 coatings were obtained after sintering Bi coatings at 673 or 773 K, while monoclinic and triclinic mixed phase Bi2O3 coatings were obtained at 873 or 973 K. The topographies of the samples were observably different, which varied from flower-like, irregular, polygonal to nanosized particles with the increase in calcination temperature. Photodegradation of malachite green under simulated solar irradiation for 180 min showed that the largest degradation efficiency of 86.2% was achieved over Bi2O3 photocatalyst coatings sintered at 873 K. The Bi2O3 photocatalyst coatings, encapsulated with Al2O3 ball with an average diameter around 1 mm, are quite easily recycled, which provides an alternative visible light-driven photocatalyst suitable for practical water treatment application.

  9. Influence of calcination process on the formation of selected air pollutants

    Science.gov (United States)

    Wydrych, Jacek; Dobrowolski, Bolesław; Borsuk, Grzegorz; Pochwała, Sławomir

    2017-10-01

    The subject of the study is to analyze the phenomena of thermal flow in the precalcinator chamber of the exchanger's furnace tower including the combustion of coal dust and decarbonisation of raw lime powder. During the research were provided development of a mathematical model of particulate solid fuels combustion, calcining the raw material, NOx and COx formation. Moreover conducting the number for the current and the upgraded design of the precalcinator and analysis of the results. In this study, a mathematical model based on Euler's method to describe the motion of the gas phase and the Lagrange method to describe the motion of particles [1-4]. In the calculations there were assumed fractional particles raw material and fuel, and the following processes: flow of exhaust gases from the rotary kiln through the precalcinator chamber, heat exchange between the particles of raw material and exhaust gases, the additional fuel combustion in the precalcinator, the process of raw material calcination, transformation of gaseous substances, effect of the additional (tertiary) air delivery on the processes in the chamber.

  10. High Pressure Synthesis versus Calcination – Different Approaches to Crystallization of Zirconium Dioxide

    Directory of Open Access Journals (Sweden)

    Kaszewski Jarosław

    2014-06-01

    Full Text Available Calcination and microwave-assisted hydrothermal processing of precipitated zirconium dioxide are compared. Characterization of synthesized products of these two technologies is presented. The infiuence of thermal treatment up to 1200oC on the structural and spectroscopic properties of the so-obtained zirconium dioxide is examined. It was found that initial crystallization of material inhibits the crystal growth up to the 800oC (by means of XRD and TEM techniques, while the material crystallized from amorphous hydroxide precursor at 400oC, exhibits 26 nm sized crystallites already. It was found using the TG technique that the temperature range 100–200oC during the calcination process is equivalent to a microwave hydrothermal process by means of water content. Mass loss is estimated to be about 18%. Based on X-ray investigations it was found that the initial hydroxide precursor is amorphous, however, its luminescence activity suggests the close range ordering in a material.

  11. Mercury removal at Idaho National Engineering and Environmental Laboratory's New Waste Calcining Facility

    Energy Technology Data Exchange (ETDEWEB)

    S. C. Ashworth

    2000-02-27

    Technologies were investigated to determine viable processes for removing mercury from the calciner (NWCF) offgas system at the Idaho National Engineering and Environmental Laboratory. Technologies for gas phase and aqueous phase treatment were evaluated. The technologies determined are intended to meet EPA Maximum Achievable Control Technology (MACT) requirements under the Clean Air Act and Resource Conservation and Recovery Act (RCRA). Currently, mercury accumulation in the calciner off-gas scrubbing system is transferred to the tank farm. These transfers lead to accumulation in the liquid heels of the tanks. The principal objective for aqueous phase mercury removal is heel mercury reduction. The system presents a challenge to traditional methods because of the presence of nitrogen oxides in the gas phase and high nitric acid in the aqueous scrubbing solution. Many old and new technologies were evaluated including sorbents and absorption in the gas phase and ion exchange, membranes/sorption, galvanic methods, and UV reduction in the aqueous phase. Process modifications and feed pre-treatment were also evaluated. Various properties of mercury and its compounds were summarized and speciation was predicted based on thermodynamics. Three systems (process modification, NOxidizer combustor, and electrochemical aqueous phase treatment) and additional technology testing were recommended.

  12. Mercury Removal at Idaho National Engineering and Environmental Laboratory's New Waste Calcining Facility

    Energy Technology Data Exchange (ETDEWEB)

    Ashworth, Samuel Clay; Wood, R. A.; Taylor, D. D.; Sieme, D. D.

    2000-03-01

    Technologies were investigated to determine viable processes for removing mercury from the calciner (NWCF) offgas system at the Idaho National Engineering and Environmental Laboratory. Technologies for gas phase and aqueous phase treatment were evaluated. The technologies determined are intended to meet EPA Maximum Achievable Control Technology (MACT) requirements under the Clean Air Act and Resource Conservation and Recovery Act (RCRA). Currently, mercury accumulation in the calciner off-gas scrubbing system is transferred to the tank farm. These transfers lead to accumulation in the liquid heels of the tanks. The principal objective for aqueous phase mercury removal is heel mercury reduction. The system presents a challenge to traditional methods because of the presence of nitrogen oxides in the gas phase and high nitric acid in the aqueous scrubbing solution. Many old and new technologies were evaluated including sorbents and absorption in the gas phase and ion exchange, membranes/sorption, galvanic methods, and UV reduction in the aqueous phase. Process modifications and feed pre-treatment were also evaluated. Various properties of mercury and its compounds were summarized and speciation was predicted based on thermodynamics. Three systems (process modification, NOxidizer combustor, and electrochemical aqueous phase treatment) and additional technology testing were recommended.

  13. Manganese oxide phases and morphologies: A study on calcination temperature and atmospheric dependence.

    Science.gov (United States)

    Augustin, Matthias; Fenske, Daniela; Bardenhagen, Ingo; Westphal, Anne; Knipper, Martin; Plaggenborg, Thorsten; Kolny-Olesiak, Joanna; Parisi, Jürgen

    2015-01-01

    Manganese oxides are one of the most important groups of materials in energy storage science. In order to fully leverage their application potential, precise control of their properties such as particle size, surface area and Mn (x) (+) oxidation state is required. Here, Mn3O4 and Mn5O8 nanoparticles as well as mesoporous α-Mn2O3 particles were synthesized by calcination of Mn(II) glycolate nanoparticles obtained through an economical route based on a polyol synthesis. The preparation of the different manganese oxides via one route facilitates assigning actual structure-property relationships. The oxidation process related to the different MnO x species was observed by in situ X-ray diffraction (XRD) measurements showing time- and temperature-dependent phase transformations occurring during oxidation of the Mn(II) glycolate precursor to α-Mn2O3 via Mn3O4 and Mn5O8 in O2 atmosphere. Detailed structural and morphological investigations using transmission electron microscopy (TEM) and powder XRD revealed the dependence of the lattice constants and particle sizes of the MnO x species on the calcination temperature and the presence of an oxidizing or neutral atmosphere. Furthermore, to demonstrate the application potential of the synthesized MnO x species, we studied their catalytic activity for the oxygen reduction reaction in aprotic media. Linear sweep voltammetry revealed the best performance for the mesoporous α-Mn2O3 species.

  14. Manganese oxide phases and morphologies: A study on calcination temperature and atmospheric dependence

    Directory of Open Access Journals (Sweden)

    Matthias Augustin

    2015-01-01

    Full Text Available Manganese oxides are one of the most important groups of materials in energy storage science. In order to fully leverage their application potential, precise control of their properties such as particle size, surface area and Mnx+ oxidation state is required. Here, Mn3O4 and Mn5O8 nanoparticles as well as mesoporous α-Mn2O3 particles were synthesized by calcination of Mn(II glycolate nanoparticles obtained through an economical route based on a polyol synthesis. The preparation of the different manganese oxides via one route facilitates assigning actual structure–property relationships. The oxidation process related to the different MnOx species was observed by in situ X-ray diffraction (XRD measurements showing time- and temperature-dependent phase transformations occurring during oxidation of the Mn(II glycolate precursor to α-Mn2O3 via Mn3O4 and Mn5O8 in O2 atmosphere. Detailed structural and morphological investigations using transmission electron microscopy (TEM and powder XRD revealed the dependence of the lattice constants and particle sizes of the MnOx species on the calcination temperature and the presence of an oxidizing or neutral atmosphere. Furthermore, to demonstrate the application potential of the synthesized MnOx species, we studied their catalytic activity for the oxygen reduction reaction in aprotic media. Linear sweep voltammetry revealed the best performance for the mesoporous α-Mn2O3 species.

  15. Photocatalytic hydrogen evolution of palladium nanoparticles decorated black TiO2 calcined in argon atmosphere

    Science.gov (United States)

    Wu, Ming-Chung; Hsiao, Kai-Chi; Chang, Yin-Hsuan; Chan, Shun-Hsiang

    2018-02-01

    Black TiO2 nanoparticles (BTN) was prepared by sol-gel derived precursor calcined in an argon atmosphere. The synthesized BTN with trivalent titanium ion, structural defect, and oxygen vacancy shows a remarkably high absorbance in the visible light spectrum. BTN thus behaves a higher visible-active nanoreactor than white TiO2 nanoparticles (WTN) in the aqueous solution for organic pollutant degradation. Moreover, palladium decoration on the BTN surface (Pd-BTN) demonstrates a fascinating clean energy application. The obtained Pd-BTN fulfills a satisfied green material demand in the photocatalytic hydrogen production application. Pd-BTN calcined at 400 °C (Pd-BTN-400) shows the high photocatalytic hydrogen generation rate of 5200 μmol/g h under UV-A irradiation and 9300 μmol/g h under UV-B irradiation, respectively. The well-developed material, Pd-BTN-400, could be one of the best solutions in the concern of clean energy and water-purification with regard to the continuous environmental issue.

  16. Cyclic carbonation calcination studies of limestone and dolomite for CO{sub 2} separation from combustion flue gases - article no. 011801

    Energy Technology Data Exchange (ETDEWEB)

    Senthoorselvan, S.; Gleis, S.; Hartmut, S.; Yrjas, P.; Hupa, M. [TUM, Garching (Germany)

    2009-01-15

    Naturally occurring limestone and dolomite samples, originating from different geographical locations, were tested as potential sorbents for carbonation/calcination based CO{sub 2} capture from combustion flue gases. Samples have been studied in a thermogravimetric analyzer under simulated flue gas conditions at three calcination temperatures, viz., 750{sup o}C, 875{sup o}C, and 930{sup o}C for four carbonation calcination reaction (CCR) cycles. The dolomite sample exhibited the highest rate of carbonation than the tested limestones. At the third cycle, its CO{sub 2} capture capacity per kilogram of the sample was nearly equal to that of Gotland, the highest reacting limestone tested. At the fourth cycle it surpassed Gotland, despite the fact that the CaCO{sub 3} content of the Sibbo dolomite was only 2/3 of that of the Gotland. Decay coefficients were calculated by a curve fitting exercise and its value is lowest for the Sibbo dolomite. That means, most probably its capture capacity per kilogram of the sample would remain higher well beyond the fourth cycle. There was a strong correlation between the calcination temperature, the specific surface area of the calcined samples, and the degree of carbonation. It was observed that the higher the calcination temperature, the lower the sorbent reactivity. For a given limestone/dolomite sample, sorbents CO{sub 2} capture capacity depended on the number of CCR cycles and the calcination temperature. According to the equilibrium thermodynamics, the CO{sub 2} partial pressure in the calciner should be lowered to lower the calcination temperature. This can be achieved by additional steam supply into the calciner. Steam could then be condensed in an external condenser to single out the CO{sub 2} stream from the exit gas mixture of the calciner. A calciner design based on this concept is illustrated.

  17. Aggregates, broccoli and cauliflower

    Science.gov (United States)

    Grey, Francois; Kjems, Jørgen K.

    1989-09-01

    Naturally grown structures with fractal characters like broccoli and cauliflower are discussed and compared with DLA-type aggregates. It is suggested that the branching density can be used to characterize the growth process and an experimental method to determine this parameter is proposed.

  18. Towards General Temporal Aggregation

    DEFF Research Database (Denmark)

    Boehlen, Michael H.; Gamper, Johann; Jensen, Christian Søndergaard

    2008-01-01

    Most database applications manage time-referenced, or temporal, data. Temporal data management is difficult when using conventional database technology, and many contributions have been made for how to better model, store, and query temporal data. Temporal aggregation illustrates well the problem...

  19. Effect of calcination temperature on microstructural and magnetic properties of CuFe2O4 spinel

    Energy Technology Data Exchange (ETDEWEB)

    Costa, A.F.; Melo, D.M.A.; Gomes, D.K.S.; Araujo, J.H.; Lima, A.C. [Universidade Federal do Rio Grande do Norte (UFRN), RN (Brazil); Pimentel, P.M. [Universidade Federal Rural do Semi-Arido (UFERSA), Mossoro, RN (Brazil); Santana, R.S.; Oliveira, R.M.P.B. [Universidade Federal de Sergipe (UFS), SE (Brazil)

    2014-07-01

    In this research, we report a study of nanostructured CuFe{sub 2}O{sub 4} Spinel obtained by a method which makes uses of gelatin as an organic precursor. The structural and magnetic properties were investigated in function of calcination temperature. The precursor powders were calcined at 700 and 900 deg C to obtain spinel phase. Then were characterized using X-ray diffraction combined with the Rietveld refinement method, infrared spectroscopy (FTIR), and magnetic measurements. The X-ray diffraction patterns revealed the presence of an inverse spinel phase, corresponding to copper ferrite in all samples. Moreover, Fe{sub 2}O{sub 3} and CuO phases were also identified. The results reveal that the calcination temperature strongly influences the magnetic properties of the prepared oxides. (author)

  20. Concrete produced with recycled aggregates

    Directory of Open Access Journals (Sweden)

    J. J. L. Tenório

    Full Text Available This paper presents the analysis of the mechanical and durable properties of recycled aggregate concrete (RAC for using in concrete. The porosity of recycled coarse aggregates is known to influence the fresh and hardened concrete properties and these properties are related to the specific mass of the recycled coarse aggregates, which directly influences the mechanical properties of the concrete. The recycled aggregates were obtained from construction and demolition wastes (CDW, which were divided into recycled sand (fine and coarse aggregates. Besides this, a recycled coarse aggregate of a specific mass with a greater density was obtained by mixing the recycled aggregates of the CDW with the recycled aggregates of concrete wastes (CW. The concrete was produced in laboratory by combining three water-cement ratios, the ratios were used in agreement with NBR 6118 for structural concretes, with each recycled coarse aggregates and recycled sand or river sand, and the reference concrete was produced with natural aggregates. It was observed that recycled aggregates can be used in concrete with properties for structural concrete. In general, the use of recycled coarse aggregate in combination with recycled sand did not provide good results; but when the less porous was used, or the recycled coarse aggregate of a specific mass with a greater density, the properties of the concrete showed better results. Some RAC reached bigger strengths than the reference concrete.

  1. Familial Aggregation of Insomnia.

    Science.gov (United States)

    Jarrin, Denise C; Morin, Charles M; Rochefort, Amélie; Ivers, Hans; Dauvilliers, Yves A; Savard, Josée; LeBlanc, Mélanie; Merette, Chantal

    2017-02-01

    There is little information about familial aggregation of insomnia; however, this type of information is important to (1) improve our understanding of insomnia risk factors and (2) to design more effective treatment and prevention programs. This study aimed to investigate evidence of familial aggregation of insomnia among first-degree relatives of probands with and without insomnia. Cases (n = 134) and controls (n = 145) enrolled in a larger epidemiological study were solicited to invite their first-degree relatives and spouses to complete a standardized sleep/insomnia survey. In total, 371 first-degree relatives (Mage = 51.9 years, SD = 18.0; 34.3% male) and 138 spouses (Mage = 55.5 years, SD = 12.2; 68.1% male) completed the survey assessing the nature, severity, and frequency of sleep disturbances. The dependent variable was insomnia in first-degree relatives and spouses. Familial aggregation was claimed if the risk of insomnia was significantly higher in the exposed (relatives of cases) compared to the unexposed cohort (relatives of controls). The risk of insomnia was also compared between spouses in the exposed (spouses of cases) and unexposed cohort (spouses of controls). The risk of insomnia in exposed and unexposed biological relatives was 18.6% and 10.4%, respectively, yielding a relative risk (RR) of 1.80 (p = .04) after controlling for age and sex. The risk of insomnia in exposed and unexposed spouses was 9.1% and 4.2%, respectively; however, corresponding RR of 2.13 (p = .28) did not differ significantly. Results demonstrate evidence of strong familial aggregation of insomnia. Additional research is warranted to further clarify and disentangle the relative contribution of genetic and environmental factors in insomnia.

  2. Concrete produced with recycled aggregates

    OpenAIRE

    Tenório,J. J. L.; Gomes,P. C. C.; Rodrigues,C. C.; Alencar,T. F. F. de

    2012-01-01

    This paper presents the analysis of the mechanical and durable properties of recycled aggregate concrete (RAC) for using in concrete. The porosity of recycled coarse aggregates is known to influence the fresh and hardened concrete properties and these properties are related to the specific mass of the recycled coarse aggregates, which directly influences the mechanical properties of the concrete. The recycled aggregates were obtained from construction and demolition wastes (CDW), which were d...

  3. Proteins aggregation and human diseases

    Science.gov (United States)

    Hu, Chin-Kun

    2015-04-01

    Many human diseases and the death of most supercentenarians are related to protein aggregation. Neurodegenerative diseases include Alzheimer's disease (AD), Huntington's disease (HD), Parkinson's disease (PD), frontotemporallobar degeneration, etc. Such diseases are due to progressive loss of structure or function of neurons caused by protein aggregation. For example, AD is considered to be related to aggregation of Aβ40 (peptide with 40 amino acids) and Aβ42 (peptide with 42 amino acids) and HD is considered to be related to aggregation of polyQ (polyglutamine) peptides. In this paper, we briefly review our recent discovery of key factors for protein aggregation. We used a lattice model to study the aggregation rates of proteins and found that the probability for a protein sequence to appear in the conformation of the aggregated state can be used to determine the temperature at which proteins can aggregate most quickly. We used molecular dynamics and simple models of polymer chains to study relaxation and aggregation of proteins under various conditions and found that when the bending-angle dependent and torsion-angle dependent interactions are zero or very small, then protein chains tend to aggregate at lower temperatures. All atom models were used to identify a key peptide chain for the aggregation of insulin chains and to find that two polyQ chains prefer anti-parallel conformation. It is pointed out that in many cases, protein aggregation does not result from protein mis-folding. A potential drug from Chinese medicine was found for Alzheimer's disease.

  4. Biodiesel production from palm oil using calcined waste animal bone as catalyst.

    Science.gov (United States)

    Obadiah, Asir; Swaroopa, Gnanadurai Ajji; Kumar, Samuel Vasanth; Jeganathan, Kenthorai Raman; Ramasubbu, Alagunambi

    2012-07-01

    Waste animal bones was employed as a cost effective catalyst for the transesterification of palm oil. The catalyst was calcined at different temperatures to transform the calcium phosphate in the bones to hydroxyapatite and 800 °C was found to give the best yield of biodiesel. The catalyst was characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), energy dispersive spectrometry (EDS) and Fourier transform infrared spectrometry (FT-IR). Under the optimal reaction conditions of 20 wt.% of catalyst, 1:18 oil to methanol molar ratio, 200 rpm of stirring of reactants and at a temperature of 65 °C, the methyl ester conversion was 96.78% and it was achieved in 4h. The catalyst performed equally well as the laboratory-grade CaO. Animal bone is therefore a useful raw material for the production of a cheap catalyst for transesterification. Copyright © 2012 Elsevier Ltd. All rights reserved.

  5. ANTI-ULCER ACTIVITY OF SHANKHA BHASMA (CALCINED CONCH-SHELL

    Directory of Open Access Journals (Sweden)

    T. K. Sur

    2013-06-01

    Full Text Available The anti-ulcer activities along with chemical identification of purified Shankha Bhasma (SBM or calcined conch-shell was undertaken. Shankha Bhasma (SBM was prepared by traditional process used in India. The chemical composition of SBM was studied by atomic absorption spectrometry and infra-red spectral analysis. Acute oral toxicity of SBM was done in Swiss mice. SBM (25 mg/kg and 50 mg/kg was studied for anti-ulcer effect on ethanol induced and pylorus ligature induced model in Wistar rats. SBM showed significant (P<0.001 positive results in both the models in comparison with respective control and standard control (omeprazole 20 mg/kg and ranitidine 50 mg/kg.

  6. Twofold role of calcined hydrotalcites in the degradation of methyl parathion pesticide

    Directory of Open Access Journals (Sweden)

    Alvaro Sampieri

    2011-02-01

    Full Text Available Methyl parathion (MP is a very toxic organophosphate pesticide used as a non-systematic insecticide and acaricide on many corps. As MP and its by-products are highly toxic, they have to be retained to avoid pollution of rivers and lakes. Highly efficient sorbents are hydrotalcites (HTs (or anionic clays. We have correlated the degradation of an aqueous solution of MP at room temperature, with the basicity of the adsorbing materials. It was found that the metal composition of hydrotalcites determines both the surface electronic properties (basic or acidic and the sorption capacity. Depending on the basic strength, some calcined hydrotalcites can catalyze the transformation of MP to p-nitrophenol (p-NP and retain its by-products. Such a process has the advantage of being able to be carried out at room temperature and at the pH of the pesticide solution.

  7. Twofold role of calcined hydrotalcites in the degradation of methyl parathion pesticide

    Science.gov (United States)

    Fetter, Geolar; Villafuerte-Castrejon, María Elena; Tejeda-Cruz, Adriana; Bosch, Pedro

    2011-01-01

    Summary Methyl parathion (MP) is a very toxic organophosphate pesticide used as a non-systematic insecticide and acaricide on many corps. As MP and its by-products are highly toxic, they have to be retained to avoid pollution of rivers and lakes. Highly efficient sorbents are hydrotalcites (HTs) (or anionic clays). We have correlated the degradation of an aqueous solution of MP at room temperature, with the basicity of the adsorbing materials. It was found that the metal composition of hydrotalcites determines both the surface electronic properties (basic or acidic) and the sorption capacity. Depending on the basic strength, some calcined hydrotalcites can catalyze the transformation of MP to p-nitrophenol (p-NP) and retain its by-products. Such a process has the advantage of being able to be carried out at room temperature and at the pH of the pesticide solution. PMID:21977419

  8. Positron annihilation lifetime spectroscopy (PALS) study of the as prepared and calcined MFI zeolites

    Science.gov (United States)

    Bosnar, Sanja; Vrankić, Martina; Bosnar, Damir; Ren, Nan; Šarić, Ankica

    2017-11-01

    The synthesis of high silica zeolites in many cases implies the usage of organic structural direction agents (SDA). However, to manifest their functionalities, the SDA occluded inside the channels of the as-synthesized structure should be removed, usually by a high temperature treatment (calcination). In this paper, the positron annihilation lifetime spectroscopy (PALS) was used to monitor the development of accessible spaces, their sizes and distributions in MFI zeolites, ZSM-5 and silicalite-1 in order to give an additional insight in the process of the SDA removal. For that purpose, a conventional PALS setup with 22Na positron source was applied. It was established that there is a pronounced difference between positron annihilation data for these two zeolites of the same structural type. The samples were additionally analysed by X-ray powder diffraction at room temperature with a crystal structure refinement and thermogravimetry.

  9. Genesis of Cr(VI) in Sri Lankan soils and its adsorptive removal by calcined gibbsite

    Science.gov (United States)

    Rajapaksha, A. U.; Wijesundara, D. M.; Vithanage, M. S.; Ok, Y. S.

    2012-12-01

    Hexavalent chromium is highly toxic to biota and considered as a priority pollutant. Industrial sources of Cr(VI) include leather tanning, plating, electroplating, anodizing baths, rinse waters, etc. In addition, weathering of ultramafic rocks rich in chromium, such as serpentine, is known to Cr(VI) sources into natural water. The Cr(III) is the most stable in the environment, however, conversion of Cr(III) into Cr(VI) occurs in soil due to presence of naturally occurring minerals such as manganese dioxides. We investigated the amount of Cr(VI) recorded from the soils from anthropogenically and naturally contaminated soils (serpentine soils) in Sri Lanka and the removal efficacy of Cr(VI) by calcined gibbsite (Al oxides). The effect of pH on Cr(VI) adsorption was determined by adjusting the pH in the range of 4-10. In the experiments, the adsorbent concentration was kept at 1 g/l of solution containing 10 mg/l Cr(VI) at 25 0C. Total chromium recorded were around 11,000 mg kg-1 and 6,000 mg kg-1 for serpentine soil and tannery waste-contaminated soil, respectively. Although total Cr was high in the contaminated soils, Cr(VI) concentration was only about 28 mg kg-1 and 210 mg kg-1 in the serpentine and tannery soils, respectively. The calcined gibbsite has maximum adsorption of 85 % around pH 4 and adsorption generally decreased with increase of pH.

  10. Assessment of natural and calcined starfish for the amelioration of acidic soil.

    Science.gov (United States)

    Moon, Deok Hyun; Yang, Jae E; Cheong, Kyung Hoon; Koutsospyros, Agamemnon; Park, Jeong-Hun; Lim, Kyoung Jae; Kim, Sung Chul; Kim, Rog-Young; Ok, Yong Sik

    2014-01-01

    Quality improvement of acidic soil (with an initial pH of approximately 4.5) with respect to soil pH, exchangeable cations, organic matter content, and maize growth was attempted using natural (NSF) and calcined starfish (CSF). Acidic soil was amended with NSF and CSF in the range of 1 to 10 wt.% to improve soil pH, organic matter content, and exchangeable cations. Following the treatment, the soil pH was monitored for periods up to 3 months. The exchangeable cations were measured after 1 month of curing. After a curing period of 1 month, the maize growth experiment was performed with selected treated samples to evaluate the effectiveness of the treatment. The results show that 1 wt.% of NSF and CSF (700 and 900 °C) were required to increase the soil pH to a value higher than 7. In the case of CSF (900 °C), 1 wt.% was sufficient to increase the soil pH value to 9 due to the strong alkalinity in the treatment. No significant changes in soil pHs were observed after 7 days of curing and up to 3 months of curing. Upon treatment, the cation exchange capacity values significantly increased as compared to the untreated samples. The organic content of the samples increased upon NSF treatment, but it remains virtually unchanged upon CSF treatment. Maize growth was greater in the treated samples rather than the untreated samples, except for the samples treated with 1 and 3 wt.% CSF (900 °C), where maize growth was limited due to strong alkalinity. This indicates that the amelioration of acidic soil using natural and calcined starfish is beneficial for plant growth as long as the application rate does not produce alkaline conditions outside the optimal pH range for maize growth.

  11. Dynamics of fire ant aggregations

    Science.gov (United States)

    Tennenbaum, Michael; Hu, David; Fernandez-Nieves, Alberto

    Fire ant aggregations are an inherently active system. Each ant harvests its own energy and can convert it into motion. The motion of individual ants contributes non-trivially to the bulk material properties of the aggregation. We have measured some of these properties using plate-plate rheology, where the response to an applied external force or deformation is measured. In this talk, we will present data pertaining to the aggregation behavior in the absence of any external force. We quantify the aggregation dynamics by monitoring the rotation of the top plate and by measuring the normal force. We then compare the results with visualizations of 2D aggregations.

  12. Stabilized γ-BIMNVOX solid electrolyte: Ethylene glycol–citrate sol–gel synthesis, microwave-assisted calcination, and structural and electrical characterization

    Energy Technology Data Exchange (ETDEWEB)

    Al-Areqi, Niyazi A.S., E-mail: niyazi.alareqi@gmail.com [Department of Chemistry, Faculty of Applied Science, Taiz University, Taiz, Republic of Yemen (Yemen); Beg, Saba [Department of Chemistry, Aligarh Muslim University, Aligarh 202002 (India); Al-Alas, Ahlam [Department of Chemistry, Faculty of Applied Science, Taiz University, Taiz, Republic of Yemen (Yemen); Hafeez, Shehla [Department of Chemistry, Aligarh Muslim University, Aligarh 202002 (India)

    2013-12-25

    Highlights: •γ-BIMNVOX was synthesized by ethylene glycol–citrate sol–gel route. •γ-BIMNVOX crystallizes by 25-min microwave-assisted calcination. •Smaller particle sizes for microwave calcined BIMNVOX samples. •Best oxide-ion performance for microwave calcined BIMNVOX samples. -- Abstract: Samples of γ-BIMNVOX (Bi{sub 2}V{sub 1−x}Mn{sub x}O{sub 5.5−x/2}; 0.13 ⩽ x ⩽ 0.20) system were synthesized by an ethylene glycol–citrate sol–gel route. The resulting xerogels were then calcined by the microwave heating using a modified domestic microwave oven operated at 2.45 GHz. Microwave-assisted calcination samples in comparison with other conventionally calcined samples were characterized in terms of phase crystallization, stabilization and particle size using simultaneous thermogravimetric–differential thermal analysis (TG–DTA), X-ray powder diffraction (XRPD) and scanning electron microscopy (SEM). The AC impedance spectroscopy was employed for electrical characterization. It was found that the microwave-assisted calcination route successfully produces better crystalline stabilized γ-BIMNVOX samples with appreciably small average particle sizes after only 25 min of microwave heating. The electrical properties of microwave calcined γ-BIMNVOX system make it an advanced low-temperature solid electrolyte suitable for use in oxide-ion based electrochemical applications.

  13. Operation of a 25 kWth Calcium Looping Pilot-plant with High Oxygen Concentrations in the Calciner.

    Czech Academy of Sciences Publication Activity Database

    Erans, M.; Jeremiáš, Michal; Manovic, V.; Anthony, E.J.

    2017-01-01

    Roč. 128, 25 OCT (2017), č. článku e56112. ISSN 1940-087X Grant - others:RFCS(XE) RFCR-CT-2014-00007 Institutional support: RVO:67985858 Keywords : calcium looping * CO2 capture * oxy-fuel calcination Subject RIV: CI - Industrial Chemistry, Chemical Engineering Impact factor: 1.232, year: 2016

  14. Influence of calcination temperature on the zirconia microstructure synthesized by complex polymerization method (CPM): a comparative study

    Energy Technology Data Exchange (ETDEWEB)

    Santos, R.L.P.; Mota, F.V.; Nascimento, R.M.; Henriques, B.P.; Silva, F.S.; Assis, R. [Universidade Federal do Rio Grande do Norte (UFRN), Natal, RN (Brazil)

    2016-07-01

    Full text: The aim of this study was to accomplish a previous characterization of the zirconia synthesized by Complex Polymerization Method (CPM) using yttria as stabilizing agent and different calcination temperatures. The powders were crystallized at 800, 900 and 1000 °C for 2h. The structural evolution Y-TZP powders were characterized by X-Ray Diffraction (XRD) and Micro-Raman Spectroscopy. The thermal properties of the calcined pre-pyrolyzed (350 °C for 4 h), samples were investigated by simultaneous thermo analysis (TGA/DTA). After heat treatment the phase Y-TZP was obtained of a single-phase, with absence of the deleterious phases. The results show that average crystallite size of the powder synthesized with 3% of Yttria dopant, increased from 11.5 to 27.9 nm when the calcination temperature increased from 800 to 1000 °C. This behavior was observed for all specimens independent of the Yttria content. The micro-Raman indicate the presence of the tetragonal phase for all samples independent of the calcination temperature employed. (author)

  15. Removal of an Acid Dye from Water Using Calcined and Uncalcined ZnAl-r Anionic Clay.

    Science.gov (United States)

    Bessaha, Hassiba; Bouraada, Mohamed; de Ménorval, Louis Charles

    2017-09-01

      The present report describes the removal of indigo carmine dye from water via adsorption on ZnAl-r hydrotalcite. Two grades of clay based on Zn/Al molar ratios of 3 and 4, uncalcined and calcined, were used. The adsorbents characterization using X-ray diffraction (XRD), Fourier transform infrared (FTIR), differential thermal and thermogravimetric analysis (DTA and TGA, respectively) revealed a layered structure for the hydrotalcite clays, whereas their calcination favored the formation of ZnO and ZnAl2O4 mixed metal oxides. The calcined materials immobilized much larger amounts of indigo carmine dye than the uncalcined layered double hydroxides (LDHs) specimens. The maximum adsorption capacities obey the order: CZnAl-4 (520.8 mg/g) > CZnAl-3 (358.4 mg/g) > ZnAl-3 (67.25 mg/g) > ZnAl-4 (21.65 mg/g). The adsorption isotherms are best described by Langmuir model. The sorption process is spontaneous in nature and its kinetics data are best described by a pseudo-second-order model. Adsorption tests on re-used calcined clays demonstrate its reusability after three thermal cycles.

  16. Use of calcination in exposing the entrapped Fe particles from multi-walled carbon nanotubes grown by chemical vapour deposition

    CSIR Research Space (South Africa)

    Kesavan Pillai, Sreejarani

    2009-03-01

    Full Text Available Multi-walled carbon nanotubes (MWCNTs) were synthesized by a chemical vapour deposition method. The effect of calcination at temperatures ranging from 300 to 550°C in exposing the metal nanoparticles within the nanotube bundles was studied...

  17. Effect of calcination environments and plasma treatment on structural, optical and electrical properties of FTO transparent thin films

    Science.gov (United States)

    Kafle, Madhav; Kapadi, Ramesh K.; Joshi, Leela Pradhan; Rajbhandari, Armila; Subedi, Deepak P.; Gyawali, Gobinda; Lee, Soo W.; Adhikari, Rajendra; Kafle, Bhim P.

    2017-07-01

    The dependence of the structural, optical and electrical properties of the FTO thin films on the film thickness (276 nm - 546 nm), calcination environment, and low temperature plasma treatment were examined. The FTO thin films, prepared by spray pyrolysis, were calcinated under air followed by either further heat treatment under N2 gas or treatment in low temperature atmospheric plasma. The samples before and after calcination under N2, and plasma treatment will be represented by Sair, SN2 and SPl, respectively, hereafter. The thin films were characterized by measuring the XRD spectra, SEM images, optical transmittance and reflectance, and sheet resistance of the films before and after calcination in N2 environment or plasma treatment. The presence of sharp and narrow multiple peaks in XRD spectra hint us that the films were highly crystalline (polycrystalline). The samples Sair with the thickness of 471 nm showed as high as 92 % transmittance in the visible range. Moreover, from the tauc plot, the optical bandgap Eg values of the Sair found to be noticeably lower than that of the samples SN2. Very surprisingly, the electrical sheet resistance (Rsh) found to decrease following the trend as Rshair > RshN2 > RshPl. The samples exposed to plasma found to possess the lowest RshPl (for film with thickness 546 nm, the RshPl was 17 Ω /sq.).

  18. Development and Testing of the Advanced CHP System Utilizing the Off-Gas from the Innovative Green Coke Calcining Process in Fluidized Bed

    Energy Technology Data Exchange (ETDEWEB)

    Chudnovsky, Yaroslav; Kozlov, Aleksandr

    2013-08-15

    Green petroleum coke (GPC) is an oil refining byproduct that can be used directly as a solid fuel or as a feedstock for the production of calcined petroleum coke. GPC contains a high amount of volatiles and sulfur. During the calcination process, the GPC is heated to remove the volatiles and sulfur to produce purified calcined coke, which is used in the production of graphite, electrodes, metal carburizers, and other carbon products. Currently, more than 80% of calcined coke is produced in rotary kilns or rotary hearth furnaces. These technologies provide partial heat utilization of the calcined coke to increase efficiency of the calcination process, but they also share some operating disadvantages. However, coke calcination in an electrothermal fluidized bed (EFB) opens up a number of potential benefits for the production enhancement, while reducing the capital and operating costs. The increased usage of heavy crude oil in recent years has resulted in higher sulfur content in green coke produced by oil refinery process, which requires a significant increase in the calcinations temperature and in residence time. The calorific value of the process off-gas is quite substantial and can be effectively utilized as an “opportunity fuel” for combined heat and power (CHP) production to complement the energy demand. Heat recovered from the product cooling can also contribute to the overall economics of the calcination process. Preliminary estimates indicated the decrease in energy consumption by 35-50% as well as a proportional decrease in greenhouse gas emissions. As such, the efficiency improvement of the coke calcinations systems is attracting close attention of the researchers and engineers throughout the world. The developed technology is intended to accomplish the following objectives: - Reduce the energy and carbon intensity of the calcined coke production process. - Increase utilization of opportunity fuels such as industrial waste off-gas from the novel

  19. Effect of RhOx/CeO2 Calcination on Metal-Support Interaction and Catalytic Activity for N2O Decomposition

    Directory of Open Access Journals (Sweden)

    Verónica Rico-Pérez

    2014-09-01

    Full Text Available The effect of the calcination conditions on the catalytic activity for N2O decomposition of 2.5% RhOx/CeO2 catalysts has been investigated. Ramp and flash calcinations have been studied (starting calcinations at 25 or 250/350 °C, respectively both for cerium nitrate and ceria-impregnated rhodium nitrate decomposition. The cerium nitrate calcination ramp has neither an effect on the physico-chemical properties of ceria, observed by XRD, Raman spectroscopy and N2 adsorption, nor an effect on the catalysts performance for N2O decomposition. On the contrary, flash calcination of rhodium nitrate improved the catalytic activity for N2O decomposition. This is attributed to the smaller size of RhOx nanoparticles obtained (smaller than 1 nm which allow a higher rhodium oxide-ceria interface, favoring the reducibility of the ceria surface and stabilizing the RhOx species under reaction conditions.

  20. Making Graphene Resist Aggregation

    Science.gov (United States)

    Luo, Jiayan

    Graphene-based sheets have stimulated great interest in many scientific disciplines and shown promise for wide potential applications. Among various ways of creating single atomic layer carbon sheets, a promising route for bulk production is to first chemically exfoliate graphite powders to graphene oxide (GO) sheets, followed by reduction to form chemically modified graphene (CMG). Due to the strong van der Waals attraction between graphene sheets, CMG tends to aggregate. The restacking of sheets is largely uncontrollable and irreversible, thus it reduces their processability and compromises properties such as accessible surface area. Strategies based on colloidal chemistry have been applied to keep CMG dispersed in solvents by introducing electrostatic repulsion to overcome the van der Waals attraction or adding spacers to increase the inter-sheet spacing. In this dissertation, two very different ideas that can prevent CMG aggregation without extensively modifying the material or introducing foreign spacer materials are introduced. The van der Waals potential decreases with reduced overlapping area between sheets. For CMG, reducing the lateral dimension from micrometer to nanometer scale should greatly enhance their colloidal stability with additional advantages of increased charge density and decreased probability to interact. The enhanced colloidal stability of GO and CMG nanocolloids makes them especially promising for spectroscopy based bio-sensing applications. For potential applications in a compact bulk solid form, the sheets were converted into paper-ball like structure using capillary compression in evaporating aerosol droplets. The crumpled graphene balls are stabilized by locally folded pi-pi stacked ridges, and do not unfold or collapse during common processing steps. They can tightly pack without greatly reducing the surface area. This form of graphene leads to scalable performance in energy storage. For example, planer sheets tend to aggregate and

  1. Structure of Viral Aggregates

    Science.gov (United States)

    Barr, Stephen; Luijten, Erik

    2010-03-01

    The aggregation of virus particles is a particular form of colloidal self-assembly, since viruses of a give type are monodisperse and have identical, anisotropic surface charge distributions. In small-angle X-ray scattering experiments, the Qbeta virus was found to organize in different crystal structures in the presence of divalent salt and non-adsorbing polymer. Since a simple isotropic potential cannot explain the occurrence of all observed phases, we employ computer simulations to investigate how the surface charge distribution affects the virus interactions. Using a detailed model of the virus particle, we find an asymmetric ion distribution around the virus which gives rise to the different phases observed.

  2. Distinguishing aggregate formation and aggregate clearance using cell-based assays

    NARCIS (Netherlands)

    Eenjes, Evelien; Dragich, Joanna M.; Kampinga, Harm H.; Yamamoto, Ai

    2016-01-01

    The accumulation of ubiquitylated proteinaceous inclusions represents a complex process, reflecting the disequilibrium between aggregate formation and aggregate clearance. Although decreasing aggregate formation or augmenting aggregate clearance will ultimately lead to a diminished aggregate burden,

  3. Infrared detection of the mineralogical aspects that influence the processing of calcined kaolin

    Science.gov (United States)

    Groenheide, Stefan; Guatame-Garcia, Adriana; Buxton, Mike; van der Werff, Harald

    2017-04-01

    Calcined kaolin is an industrial minerals product used in the production of paper, paint, rubber and other specialty applications. It is produced from kaolinite through a series of refinement steps and final calcination at temperatures of above 900°C, with the aim of generating a whiter and more abrasive material. The raw kaolin ore is a mixture of clay minerals, quartz and feldspars, where kaolinite is the main constituent. The optimal kaolin ores to feed the processing plant should ideally have high kaolinite abundance, be free in Fe-bearing mineralogy (to avoid influence in the colour of the product), and the kaolinite itself should be of high crystallinity (to ensure the correct abrasiveness after calcination). This work presents a case study from the kaolin deposits in the St. Austell Granite (South-West England), which are known for their high quality and world-class size. In this area, the kaolin is of primary-hydrothermal origin, with mineral associations that are related to the genetic history. The eventual depletion of the high-quality reserves is bringing now the attention to the lower grade zones, where the amount of impurities increases. As a consequence, it is critical to developing strategies that ensure the supply of high-quality ore to the processing plant. For this, it is necessary to acquire a thorough knowledge of the ore, including relative abundance of the minerals and their textural relationships. Hyperspectral images in the visible-near infrared (VNIR) and short-wave infrared (SWIR) ranges were collected from drill cores and run-off-mine (ROM) samples, obtained from one of the kaolin pits in the St. Austell area, where the kaolin quality is known to be lower than in the rest of the deposit. A series of mineral maps were generated to assess the distribution, texture and abundance of the Fe-bearing mineralogy and the other kaolin-associated minerals, as well as the variations in the crystallinity of kaolinite. The mineral maps enabled the

  4. Generalized Test Plan for the Vitrification of Simulated High-Level -Waste Calcine in the Idaho National Laboratory‘s Bench -Scale Cold Crucible Induction Melter

    Energy Technology Data Exchange (ETDEWEB)

    Vince Maio

    2011-08-01

    This Preliminary Idaho National Laboratory (INL) Test Plan outlines the chronological steps required to initially evaluate the validity of vitrifying INL surrogate (cold) High-Level-Waste (HLW) solid particulate calcine in INL's Cold Crucible Induction Melter (CCIM). Its documentation and publication satisfies interim milestone WP-413-INL-01 of the DOE-EM (via the Office of River Protection) sponsored work package, WP 4.1.3, entitled 'Improved Vitrification' The primary goal of the proposed CCIM testing is to initiate efforts to identify an efficient and effective back-up and risk adverse technology for treating the actual HLW calcine stored at the INL. The calcine's treatment must be completed by 2035 as dictated by a State of Idaho Consent Order. A final report on this surrogate/calcine test in the CCIM will be issued in May 2012-pending next fiscal year funding In particular the plan provides; (1) distinct test objectives, (2) a description of the purpose and scope of planned university contracted pre-screening tests required to optimize the CCIM glass/surrogate calcine formulation, (3) a listing of necessary CCIM equipment modifications and corresponding work control document changes necessary to feed a solid particulate to the CCIM, (4) a description of the class of calcine that will be represented by the surrogate, and (5) a tentative tabulation of the anticipated CCIM testing conditions, testing parameters, sampling requirements and analytical tests. Key FY -11 milestones associated with this CCIM testing effort are also provided. The CCIM test run is scheduled to be conducted in February of 2012 and will involve testing with a surrogate HLW calcine representative of only 13% of the 4,000 m3 of 'hot' calcine residing in 6 INL Bin Sets. The remaining classes of calcine will have to be eventually tested in the CCIM if an operational scale CCIM is to be a feasible option for the actual INL HLW calcine. This remaining calcine

  5. Platelet aggregation following trauma

    DEFF Research Database (Denmark)

    Windeløv, Nis A; Sørensen, Anne M; Perner, Anders

    2014-01-01

    We aimed to elucidate platelet function in trauma patients, as it is pivotal for hemostasis yet remains scarcely investigated in this population. We conducted a prospective observational study of platelet aggregation capacity in 213 adult trauma patients on admission to an emergency department (ED......). Inclusion criteria were trauma team activation and arterial cannula insertion on arrival. Blood samples were analyzed by multiple electrode aggregometry initiated by thrombin receptor agonist peptide 6 (TRAP) or collagen using a Multiplate device. Blood was sampled median 65 min after injury; median injury...... severity score (ISS) was 17; 14 (7%) patients received 10 or more units of red blood cells in the ED (massive transfusion); 24 (11%) patients died within 28 days of trauma: 17 due to cerebral injuries, four due to exsanguination, and three from other causes. No significant association was found between...

  6. Prion protein dynamics before aggregation

    National Research Council Canada - National Science Library

    Srivastava, Kinshuk Raj; Lapidusa, Lisa J

    2017-01-01

      Prion diseases, like Alzheimer's disease and Parkinson disease, are rapidly progressive neurodegenerative disorders caused by misfolding followed by aggregation and accumulation of protein deposits in neuronal cells...

  7. Novel aspects of platelet aggregation

    Directory of Open Access Journals (Sweden)

    Roka-Moya Y. M.

    2014-01-01

    Full Text Available The platelet aggregation is an important process, which is critical for the hemostatic plug formation and thrombosis. Recent studies have shown that the platelet aggregation is more complex and dynamic than it was previously thought. There are several mechanisms that can initiate the platelet aggregation and each of them operates under specific conditions in vivo. At the same time, the influence of certain plasma proteins on this process should be considered. This review intends to summarize the recent data concerning the adhesive molecules and their receptors, which provide the platelet aggregation under different conditions.

  8. Phase and morphology evolution of (Na1-xKxNbO3 powders related to calcinations and K2CO3 content

    Directory of Open Access Journals (Sweden)

    Steven J. Milne

    2007-03-01

    Full Text Available Sodium-potassium niobate ((Na1-xKxNbO3 powders with x = 0.2, 0.4, 0.6 and 0.8 were prepared following the conventional mixed oxide method and characterized by TG-DTA, XRD and SEM techniques.The effects of calcination temperature, dwell time and K2CO3 content on phase formation behavior and morphology of the powders were investigated. The calcination temperature and dwell time were found tohave a pronounced effect on the phase formation of the calcined sodium-potassium niobate powders. It was found that the crystallized phase depended on calcination conditions. The high calcination temperature andlong dwell time clearly favored particle growth and the formation of large and hard agglomerates. All the (Na1-xKxNbO3 powders showed a similar orthorhombic phase structure. The K2CO3 content significantlyaffected the calcination temperature and particle size and shape. Large particle size, cubic shape and a lower calcined condition were observed in (Na1-xKxNbO3 powder with low K2CO3 content (x = 0.2.

  9. The effect of calcination on reactive milling of anthracite as potential precursor for graphite production

    Energy Technology Data Exchange (ETDEWEB)

    Burgess-Clifford, Caroline E.; Van Essendelft, Dirk T. [The EMS Energy Institute, C211 Coal Utilization Laboratory, Penn State University, University Park, PA 16802 (United States); Narayanan, Deepa L. [Puget Sound Energy, 10885 NE 4th PSE-09S, Bellevue, WA 98004 (United States); Jain, Puja; Lueking, Angela D. [Department of Energy and Mineral Engineering, Pennsylvania State University, 120 Hosler, University Park, PA 16802 (United States); Sakti, Apurba [School of Earth Atmospheric and Environmental Sciences, University of Manchester, Manchester (United Kingdom)

    2009-12-15

    The effect of a pretreatment using reactive ball milling and calcination on the graphitizability of an anthracite coal is explored. A thermal anneal of Buck Mountain anthracite at 1400 C in argon increased the L{sub c} crystallite dimension (from 12 to 20 A) and led to an increase in the oxidation temperature of the product. Ball milling of the coal reduced particle size with a nominal effect on carbon order and the degree of graphitization after the 1400 C thermal anneal (L{sub c} from 18 to 29 A). Ball milling in cyclohexene led to a substantial increase in the graphitizability at 1400 C (L{sub c} from 12 to 50 A). The enhanced reactivity was due to both carbon structure and introduced metal. The products of the mechano-chemical pretreatment and thermal anneal consisted of nanographene ribbons and multi-walled nanopolyhedral particles. It oxidized at moderate temperatures and had a high (74.3%) degree of graphitization based on X-ray diffraction analysis; the derived material has potential as filler for production of graphite. (author)

  10. Research about the pozzolanic activity of waste materials from calcined clay

    Directory of Open Access Journals (Sweden)

    Sánchez de Rojas, M. I.

    2001-03-01

    Full Text Available To recycle and reutilise waste materials and find definite applications for their use, it is necessary to have a deep knowledge of them. The aim of this study is to study the possibility of using waste materials from calcined clay, actually ceramic tile, once crushed and grounded, as pozzolanic material. For this purpose, different tests are carried out in order to establish the pozzolanic activity of this material. At the same time, these results are compared to those of other industrial by-products, fly ash and silica fume, which are pozzolanic materials usually employed to elaborate mortars and concretes.

    Para llevar a cabo labores encaminadas al reciclado y revalorización de residuos es necesario un conocimiento profundo de los mismos, de forma que se busquen aplicaciones concretas de uso. El objetivo de este estudio es investigar la posibilidad de utilizar materiales de desecho procedentes de arcilla cocida, concretamente teja cerámica, una vez triturada y molida, como puzolana. Para ello, se efectúan diferentes ensayos dirigidos a establecer la actividad puzolanica del material. A su vez, estos resultados son comparados con otros residuos industriales, ceniza volante y humo de sílice, habituales en la elaboración de morteros y hormigones.

  11. Stabilization of lead and copper contaminated firing range soil using calcined oyster shells and fly ash.

    Science.gov (United States)

    Moon, Deok Hyun; Park, Jae-Woo; Cheong, Kyung Hoon; Hyun, Seunghun; Koutsospyros, Agamemnon; Park, Jeong-Hun; Ok, Yong Sik

    2013-12-01

    A stabilization/solidification treatment scheme was devised to stabilize Pb and Cu contaminated soil from a firing range using renewable waste resources as additives, namely waste oyster shells (WOS) and fly ash (FA). The WOS, serving as the primary stabilizing agent, was pre-treated at a high temperature to activate quicklime from calcite. Class C FA was used as a secondary additive along with the calcined oyster shells (COS). The effectiveness of the treatment was evaluated by means of the toxicity characteristic leaching procedure (TCLP) and the 0.1 M HCl extraction tests following a curing period of 28 days. The combined treatment with 10 wt% COS and 5 wt% FA cause a significant reduction in Pb (>98 %) and Cu (>96 %) leachability which was indicated by the results from both extraction tests (TCLP and 0.1 M HCl). Scanning electron microscopy-energy dispersive X-ray spectroscopy (SEM-EDX) analyses are used to investigate the mechanism responsible for Pb and Cu stabilization. SEM-EDX results indicate that effective Pb and Cu immobilization using the combined COS-FA treatment is most probably associated with ettringite and pozzolanic reaction products. The treatment results suggest that the combined COS-FA treatment is a cost effective method for the stabilization of firing range soil.

  12. Environmental assessment: Closure of the Waste Calcining Facility (CPP-633), Idaho National Engineering Laboratory

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1996-07-01

    The U.S. Department of Energy (DOE) proposes to close the Waste Calcining Facility (WCF). The WCF is a surplus DOE facility located at the Idaho Chemical Processing Plant (ICPP) on the Idaho National Engineering Laboratory (INEL). Six facility components in the WCF have been identified as Resource Conservation and Recovery Ace (RCRA)-units in the INEL RCRA Part A application. The WCF is an interim status facility. Consequently, the proposed WCF closure must comply with Idaho Rules and Standards for Hazardous Waste contained in the Idaho Administrative Procedures Act (IDAPA) Section 16.01.05. These state regulations, in addition to prescribing other requirements, incorporate by reference the federal regulations, found at 40 CFR Part 265, that prescribe the requirements for facilities granted interim status pursuant to the RCRA. The purpose of the proposed action is to reduce the risk of radioactive exposure and release of hazardous constituents and eliminate the need for extensive long-term surveillance and maintenance. DOE has determined that the closure is needed to reduce potential risks to human health and the environment, and to comply with the Idaho Hazardous Waste Management Act (HWMA) requirements.

  13. Chloride adsorption by calcined layered double hydroxides in hardened Portland cement paste

    KAUST Repository

    Yoon, Seyoon

    2014-06-01

    This study investigated the feasibility of using calcined layered double hydroxides (CLDHs) to prevent chloride-induced deterioration in reinforced concrete. CLDHs not only adsorbed chloride ions in aqueous solution with a memory effect but also had a much higher binding capacity than the original layered double hydroxides (LDHs) in the cement matrix. We investigated this adsorption in hardened cement paste in batch cultures to determine adsorption isotherms. The measured and theoretical binding capacities (153 mg g -1 and 257 mg g-1, respectively) of the CLDHs were comparable to the theoretical capacity of Friedel\\'s salt (2 mol mol-1 or 121 mg g-1), which belongs to the LDH family among cementitious phases. We simulated chloride adsorption by CLDHs through the cement matrix using the Fickian model and compared the simulation result to the X-ray fluorescence (XRF) chlorine map. Based on our results, it is proposed that the adsorption process is governed by the chloride transport through the cement matrix; this process differs from that in an aqueous solution. X-ray diffraction (XRD) analysis showed that the CLDH rebuilds the layered structure in a cementitious environment, thereby demonstrating the feasibility of applying CLDHs to the cement and concrete industries. © 2014 Published by Elsevier B.V. All rights reserved.

  14. Draft environmental assessment -- Closure of the Waste Calcining Facility (CPP-633), Idaho National Engineering Laboratory

    Energy Technology Data Exchange (ETDEWEB)

    Braun, J.B.; Irving, J.S.; Staley, C.S.; Stanley, N.

    1996-04-01

    The DOE-Idaho Operations Office has prepared an environmental assessment (EA) to analyze the environmental impacts of closing the Waste Calcining Facility (WCF) at the Idaho National Engineering Laboratory (INEL). The purpose of the action is to reduce the risk of radioactive exposure and release of radioactive and hazardous constituents and eliminate the need for extensive long-term surveillance and maintenance. DOE has determined that the closure is needed to reduce these risks to human health and the environment and to comply with Resource Conservation and Recovery Act requirements. The WCF closure project is described in the DOE Programmatic Spent Nuclear Fuel Management and Idaho National Engineering Laboratory Environmental Restoration and Waste Management Programs Final Environmental Impact Statement (Programmatic EIS). DOE determined in the Programmatic EIS Record of Decision (ROD) that certain actions would be implemented and other actions deferred. The EA examined the potential environmental impacts of the proposed action and evaluated reasonable alternatives, including the no action alternative in accordance with the Council on Environmental Quality Regulations. Based on the analysis in the EA, the action will not have a significant effect on the human environment.

  15. Enhancement of biohydrogen production from brewers' spent grain by calcined-red mud pretreatment.

    Science.gov (United States)

    Zhang, Jishi; Zang, Lihua

    2016-06-01

    This paper investigated the utilization of calcined-red mud (CRM) pretreatment to enhance fermentative hydrogen yields from brewers' spent grain (BSG). The BSG samples were treated with different concentrations (0.0-20g/L) of CRM at 55°C for 48h, before the biohydrogen process with heat-treated anaerobic sludge inoculum. The highest specific hydrogen production of 198.62ml/g-VS was obtained from the BSG treated with 10g/L CRM, with the corresponding lag time of 10.60h. Hydrogen yield increments increased by 67.74%, compared to the control tests without CRM. The results demonstrated that the CRM could hydrolyze more cellulose and further provided adequate broth and suitable pH value for efficient fermentative hydrogen. The model-based analysis showed that the modified Gompertz model presented a better fit for the experimental data than the first-order model. Copyright © 2016 Elsevier Ltd. All rights reserved.

  16. Regeneration of Waste Edible Oil by the Use of Virgin and Calcined Magnesium Hydroxide as Adsorbents.

    Science.gov (United States)

    Ogata, Fumihiko; Kawasaki, Naohito

    2016-01-01

    In this study, we prepared virgin (S, L) and calcined (S-380, S-1000, L-380, L-1000) magnesium hydroxide for regeneration of waste edible oil. Deterioration of soybean oil, rapeseed oil, and olive oil was achieved by heat and aeration treatment. The properties of the different adsorbents were investigated using specific surface area measurements, scanning electron microscopy, X-ray diffraction analysis, thermogravimetric-differential thermal analysis, and surface pH measurement. Moreover, the relationship between the changes in acid value (AV) and carbonyl value (CV) and the adsorbent properties were evaluated. The specific surface areas of S-380 and L-380 were greater than that of other adsorbents. In addition, the XRD results show that S-380 and L-380 contain both magnesium hydroxide and magnesium oxide structures. The decreases in AV and CV using S-380 and L-380 were greater than achieved using other adsorbents. The correlation coefficients between the decrease in AV and CV and specific surface area were 0.947 for soybean oil, 0.649 for rapeseed oil, and 0.773 for olive oil, respectively. The results obtained in this study suggest that a physical property of the adsorbent, namely specific surface area, was primarily responsible for the observed decreases in AV and CV. Overall, the results suggest that S-380 and L-380 are useful for the regeneration of waste edible oil.

  17. Advanced mineral calciner for regeneration of lime. Final report, March 1995--May 1997

    Energy Technology Data Exchange (ETDEWEB)

    Namazian, M.; Nickeson, R.; Lovas, B.; Miller, G.; Kelly, J.

    1997-12-31

    There are approximately 800 pulp, paper and paperboard mills in the United States. Pulp and paper is the ninth largest industry in US, uses 2.8 quads of energy per year and ranks third among all domestic US industries in the cost of energy consumed. A significant fraction of the energy consumed in pulp and paper plants is needed to recover chemicals that are used in breaking down the wood chips into pulp. In particular, 0.1 quads of energy per year are used to regenerate lime. Furthermore, pulp and paper plant operations generate 9,870 tons of NOx per year. Additionally over two million tons of spent lime are sent to landfills each year. In addition, growth in paper demand and changes in plant processes (e.g., bleaching), as a result of environmental pressures, will continue to drive the need for more lime regeneration capacity. Unless the increased capacity can be delivered productively and inexpensively, the growth in pulp and paper may occur in overseas markets. Furthermore, if new environmental constraints cannot be met at low cost, existing US pulp and paper production capacity may also move off-shore. The advanced mineral calciner (AMC) technology was developed to address this lime regeneration need. Prior to describing the technology, and the program of work that was used to test the concept, conventional lime regeneration systems and their limitations are described.

  18. Heavy metal stabilization in contaminated soil by treatment with calcined cockle shell.

    Science.gov (United States)

    Islam, Mohammad Nazrul; Taki, Golam; Nguyen, Xuan Phuc; Jo, Young-Tae; Kim, Jun; Park, Jeong-Hun

    2017-03-01

    In several previous studies, the efficacy of various liming waste materials on the immobilization of heavy metals has been tested and it was found that soils contaminated with heavy metals can be stabilized using this technique. Since lime (CaO) has been identified as the main phase of calcined cockle shell (CCS), it was hypothesized that CCS could be used as a soil amendment to immobilize heavy metals in soil. However, to date, no studies have been conducted using CCS. In this study, the effectiveness of CCS powder on the immobilization of Cd, Pb, and Zn in mine tailing soil was evaluated. After 28 days of incubation, the treated soil samples were exposed to weathering (four cycles of freezing-thawing and four cycles of wetting-drying) for 8 days before being subjected to a leaching test. The results of this study revealed that the soil pH increased from 7.5 to 12.2 with the addition of 5% CCS. A similar soil pH was obtained when the soil was amended with 5% pure CaO. By leaching with 0.1 M HCl, extracted Cd, Pb, and Zn were reduced by up to 85, 85, and 91%, respectively. Therefore, CCS is suggested as a low-cost lime-based soil amendment for stabilizing heavy metals in abandoned mining sites.

  19. CO{sub 2} capture with calcined dolomite: the effect of sorbent particle size

    Energy Technology Data Exchange (ETDEWEB)

    Stendardo, Stefano [Italian National Agency for New Technologies, Energy and Sustainable Economic Development, Rome (Italy); Di Felice, Luca; Gallucci, Katia; Foscolo, Pier Ugo [University of L' Aquila, L' Aquila (Italy)

    2011-09-15

    This investigation is set in the more comprehensive study of an innovative fluidized bed reformer configuration for producing hydrogen from either biomass/coal syngas or natural gas, in which capture of carbon dioxide by-product occurs in parallel with steam reforming and water-gas shift reactions. Reported here are experimental data of carbon dioxide absorption by particles of calcined dolomite included in a bed of otherwise inert material; the bed, initially fluidized by nitrogen, was subjected to a step concentration input of carbon dioxide and the sorption kinetics was obtained from the outlet response of the entire system. The influence of dolomite particle size was investigated - from 98 to 1,550 {mu}m - and a previously developed grain model was used to relate the observed effect of particle diameter to the complex mechanism of carbon dioxide capture in a solid sorbent. The results show that pore shrinking effects during the carbon dioxide capture process become increasingly more significant as the particle size is increased. (orig.)

  20. Linking the Physicochemical Properties of Calcined Titania Nanoparticles with Their Biocidal Activity

    Directory of Open Access Journals (Sweden)

    Changseok Han

    2016-12-01

    Full Text Available Titanium dioxide nanoparticles (nTiO2 show biocidal activity when exposed to UV illumination. Modification of their physical properties can expand their photoresponse region toward visible light. In this study, such modification was made through a sol-gel synthesis followed by calcination at a range of temperatures (250–900 °C, generating a series of nTiO2 particles with different crystal phases, sizes, porosities, zeta potentials, and BET surface areas. The unique properties of nTiO2 were linked to their toxicity to the marine bacterium, Vibrio fischeri. A modified “Flash” high-through put assay was used to test the viability of these marine organisms after short term (15–60 min exposure under visible light only to the individual groups of nTiO2 (500–2000 μg/mL. Linear regression analysis indicated that across all concentrations and time points, high biocidal activity correlated with the amorphous and anatase crystal phases, high BET surface area, high pore volume and small crystal size. The linkage between physicochemistry and nanotoxicity would be helpful for future design of more efficient and sustainable nTiO2.

  1. Electron transfer behavior and water photodecomposition ability of calcined material from a cerium-S-phenylene-O-holmium-O-phenylene-S hybrid copolymer.

    Science.gov (United States)

    Matsui, Hideo; Otsuki, Keigo; Yamada, Hiroyoshi; Kawahara, Tetsuro; Yoshihara, Masakuni

    2006-05-15

    Calcination of a cerium-S-phenylene-O-holmium-O-phenylene-S hybrid copolymer under a vacuum gave cerium oxide-carbon cluster-holmium oxide composite material. The material calcined at 600 degrees C loaded with Pt particles could decompose water to H2 and O2 with a H2/O2 ratio of 2 under visible light irradiation. ESR spectral examinations of the calcined materials revealed the possibility of a two-step electron transfer in the process of CeO2 --> carbon cluster --> Ho2O3 --> Pt with an oxidation site at CeO2 particles and a reduction site at Pt particles.

  2. Solution combustion synthesis: Effect of calcination and sintering temperature on structural, dielectric and ferroelectric properties of five layer Aurivillius oxides

    Science.gov (United States)

    Dubey, Shivangi; Subohi, Oroosa; Kurchania, Rajnish

    2017-09-01

    The effect of calcination temperature on phase formation and sintering temperature on structural, dielectric, electrical and ferroelectric properties of Ba2Bi4Ti5O18 (BBT), Pb2Bi4Ti5O18 (PBT) and Sr2Bi4Ti5O18 (SBT) ceramics prepared by solution combustion route using glycine as a fuel are investigated in this paper. Calcination temperature was optimized at 650 °C for BBT and 750 °C for SBT and PBT, at which these compounds showed pure phase formation. It was observed that density and grain size of the sintered pellets increases with increasing sintering temperature. The dielectric constant was found to be dependent on grain size and density. Transition temperature, activation energy and remnant polarization were found to increase with an increase in sintering temperature. Porosity and conductivity decreases with an increase in the sintering temperature. Thus improving the dielectric, electrical and ferroelectric properties of five layered Aurivillius oxides.

  3. Comparative studies on physico-mechanical properties of composite materials of low density polyethylene and raw/calcined kaolin

    Directory of Open Access Journals (Sweden)

    Amit Mallik

    2015-06-01

    Full Text Available The paper describes the preparation of the composite materials of low density polyethylene (LDPE as the base mixed separately with raw kaolin and the same calcined at 800 °C under the same variation in weight percentage using single-screw extruder and a mixing machine operated at a temperature between 190 and 200 °C. Some of the mechanical and physical properties such as Young's modulus, elongation at break, shore hardness and water absorption were determined at different weight fractions of filler (0, 2, 7, 10 and 15%. It was found that the addition of filler increases the mechanical properties. Absorption test was done in water at different immersion times for different composites. The degree of water absorption of composite materials was found to decrease with increasing wt% of kaolin filler (0–15% according to Fick's law. Calcined kaolin produces better mechanical properties than raw kaolin.

  4. Characterization and use of in natura and calcined rice husks for biosorption of heavy metals ions from aqueous effluents

    Directory of Open Access Journals (Sweden)

    M. G. A. Vieira

    2012-09-01

    Full Text Available Heavy metal removal by adsorption using rice husks as a bioadsorbent was evaluated as an alternative for wastewater treatment. Batch equilibrium experiments and kinetic sorption studies were performed using monocomponent solutions of Ni(II, Cd(II, Zn(II, Pb(II and Cu(II in surface samples of in natura(RH and calcined rice husks (RHA. RHA showed higher potential for removing lead and copper. Experimental data for adsorption isotherms of lead and copper were adjusted by Langmuir, Freundlich and Dubinin-Radushkevick (D-R models, being better represented by the Langmuir model. The calcination of RH increased its surface area, improving its adsorption properties. From a morphological analysis obtained by SEM and diffraction patterns (XRD, a longitudinal fibrous and amorphous structure was observed for RH. TGA resultsindicated a total mass loss of around 60% for RH and 24.5% for RHA.

  5. Influence of calcinated starfish powder on growth, yield, spawn run and primordial germination of king oyster mushroom (Pleurotus eryngii).

    Science.gov (United States)

    Choi, Ung-Kyu; Bajpai, Vivek K; Lee, Nan-Hee

    2009-11-01

    This study was undertaken to assess the calcium absorption efficacy of Pleurotus eryngii (king oyster mushroom) in sawdust medium supplemented with starfish powder and to determine the effect of starfish powder as calcium supplement on growth, yield, spawn run and primordial germination of P. eryngii. Optimum calcination of starfish powder was achieved at the temperature ranging from 560.1 to 649.5 degrees C. A 1% supplementation of starfish powder in sawdust medium did not suppress the growth of P. eryngii. Also the supplementation of 1% calcinated starfish powder to sawdust medium potentially increased the calcium content up to a level of 256.0+/-16.3 in the fruiting body of P. eryngii without extension of spawn run period and the retardation of the days to primordial germination.

  6. Effects of calcination temperature on microstructures and photocatalytic activity of titanate nanotube films prepared by an EPD method.

    Science.gov (United States)

    Yu, Jiaguo; Zhou, Minghua

    2008-01-30

    Titanate nanotube films are fabricated on F-doped SnO(2)-coated glass substrates via an electrophoretic deposition method using hydrothermally prepared titanate nanotubes as precursors. The effects of calcination temperature on the microstructures and photoactivity of as-prepared titanate nanotube films are investigated and discussed. The results indicate that the intercalated sodium ions (Na(+)) in the as-prepared titanate nanotubes are easily removed during the electrophoretic deposition. The phase transformation of titanate to anatase and diffusion of Na(+) ions from glass substrates into films occur at 400 °C. With increasing calcination temperature, the crystallization of anatase enhances and sodium content in the films increases. At 500 °C, the tubular structure still holds and the films show the highest photocatalytic activity probably due to their good crystallization, large specific surface areas and tubular structures.

  7. Exciton dynamics in molecular aggregates

    NARCIS (Netherlands)

    Augulis, R.; Pugžlys, A.; Loosdrecht, P.H.M. van; Pugzlys, A

    2006-01-01

    The fundamental aspects of exciton dynamics in double-wall cylindrical aggregates of cyanine dyes are studied by means of frequency resolved femtosecond pump-probe spectroscopy. The collective excitations of the aggregates, resulting from intermolecular dipole-dipole interactions have the

  8. Collective Rationality in Graph Aggregation

    NARCIS (Netherlands)

    Endriss, U.; Grandi, U.; Schaub, T.; Friedrich, G.; O'Sullivan, B.

    2014-01-01

    Suppose a number of agents each provide us with a directed graph over a common set of vertices. Graph aggregation is the problem of computing a single “collective” graph that best represents the information inherent in this profile of individual graphs. We consider this aggregation problem from the

  9. Decomposition of methane over alumina supported Fe and Ni–Fe bimetallic catalyst: Effect of preparation procedure and calcination temperature

    Directory of Open Access Journals (Sweden)

    A.S. Al-Fatesh

    2018-02-01

    Full Text Available Catalytic decomposition of methane has been studied extensively as the production of hydrogen and formation of carbon nanotube is proven crucial from the scientific and technological point of view. In that context, variation of catalyst preparation procedure, calcination temperature and use of promoters could significantly alter the methane conversion, hydrogen yield and morphology of carbon nanotubes formed after the reaction. In this work, Ni promoted and unpromoted Fe/Al2O3 catalysts have been prepared by impregnation, sol–gel and co-precipitation method with calcination at two different temperatures. The catalysts were characterized by X-ray diffraction (XRD, N2 physisorption, temperature programmed reduction (TPR and thermogravimetric analysis (TGA techniques. The catalytic activity was tested for methane decomposition reaction. The catalytic activity was high when calcined at 500 °C temperature irrespective of the preparation method. However while calcined at high temperature the catalyst prepared by impregnation method showed a high activity. It is found from XRD and TPR characterization that disordered iron oxides supported on alumina play an important role for dissociative chemisorptions of methane generating molecular hydrogen. The transmission electron microscope technique results of the spent catalysts showed the formation of carbon nanotube which is having length of 32–34 nm. The Fe nanoparticles are present on the tip of the carbon nanotube and nanotube grows by contraction–elongation mechanism. Among three different methodologies impregnation method was more effective to generate adequate active sites in the catalyst surface. The Ni promotion enhances the reducibility of Fe/Al2O3 oxides showing a higher catalytic activity. The catalyst is stable up to six hours on stream as observed in the activity results.

  10. Aggregating energy flexibilities under constraints

    DEFF Research Database (Denmark)

    Valsomatzis, Emmanouil; Pedersen, Torben Bach; Abello, Alberto

    2016-01-01

    The flexibility of individual energy prosumers (producers and/or consumers) has drawn a lot of attention in recent years. Aggregation of such flexibilities provides prosumers with the opportunity to directly participate in the energy market and at the same time reduces the complexity of scheduling...... the energy units. However, aggregated flexibility should support normal grid operation. In this paper, we build on the flex-offer (FO) concept to model the inherent flexibility of a prosumer (e.g., a single flexible consumption device such as a clothes washer). An FO captures flexibility in both time...... and amount dimensions. We define the problem of aggregating FOs taking into account grid power constraints. We also propose two constraint-based aggregation techniques that efficiently aggregate FOs while retaining flexibility. We show through a comprehensive evaluation that our techniques, in contrast...

  11. Effect of calcination temperature on formaldehyde oxidation performance of Pt/TiO2 nanofiber composite at room temperature

    Science.gov (United States)

    Xu, Feiyan; Le, Yao; Cheng, Bei; Jiang, Chuanjia

    2017-12-01

    Catalytic oxidation at room temperature over well-designed catalysts is an environmentally friendly method for the abatement of indoor formaldehyde (HCHO) pollution. Herein, nanocomposites of platinum (Pt) and titanium dioxide (TiO2) nanofibers with various phase compositions were prepared by calcining the electrospun TiO2 precursors at different temperatures and subsequently depositing Pt nanoparticles (NPs) on the TiO2 through a NaBH4-reduction process. The phase compositions and structures of Pt/TiO2 can be easily controlled by varying the calcination temperature. The Pt/TiO2 nanocomposites showed a phase-dependent activity towards the catalytic HCHO oxidation. Pt/TiO2 containing pure rutile phase showed enhanced activity with a turnover frequency (TOF) of 16.6 min-1 (for a calcination temperature of 800 °C) as compared to those containing the anatase phase or mixed phases. Density functional theory calculation shows that TiO2 nanofibers with pure rutile phase have stronger adsorption ability to Pt atoms than anatase phase, which favors the reduction of Pt over rutile phase TiO2, leading to higher contents of metallic Pt in the nanocomposite. In addition, the Pt/TiO2 with rutile phase possesses more abundant oxygen vacancies, which is conducive to the activation of adsorbed oxygen. Consequently, the Pt/rutile-TiO2 nanocomposite exhibited better catalytic activity towards HCHO oxidation at room temperature.

  12. Enhanced remediation of Cr(VI)-contaminated soil by incorporating a calcined-hydrotalcite-based permeable reactive barrier with electrokinetics.

    Science.gov (United States)

    Zhang, Jia; Xu, Yunfeng; Li, Wentao; Zhou, Jizhi; Zhao, Jun; Qian, Guangren; Xu, Zhi Ping

    2012-11-15

    This paper describes the enhanced Cr(VI)-contaminated soil remediation via a combination of electrokinetics (EK) with a calcined-hydrotalcite-based permeable reactive barrier (PRB). First, this combination proved to be feasible, and remarkably facilitated Cr(VI) remediation in a column test. Then, lightly-to-severely (0.16-1.65 mg/g) Cr(VI)-contaminated soil was remediated in a simulated test with the calcined hydrotalcite as the PRB under an voltage of 10-30 V (i.e. an electric field intensity of 0.7-2.0 V/cm). The observations demonstrated that both PRB and EK are critical to efficient remediation and the high de-contamination efficiency is supposedly attributed to the synergistic effect, for which EK concentrates anionic chromate to the anode region and PRB media (calcined hydrotalcite) absorbs and immobilizes it. Thus we have shown that the combined PRB-EK system is highly adaptive and effective in remediation of a larger area contaminated with chromate and various anionic pollutants. Copyright © 2012 Elsevier B.V. All rights reserved.

  13. Atmospheric pressure plasma assisted calcination by the preparation of TiO2 fibers in submicron scale

    Science.gov (United States)

    Medvecká, Veronika; Kováčik, Dušan; Zahoranová, Anna; Černák, Mirko

    2018-01-01

    Atmospheric pressure plasma assisted calcination by the preparation of TiO2 submicron fibers as a low-temperature alternative to the conventional thermal annealing was studied. A special type of dielectric barrier discharge was used for plasma treatment of hybrid titanium butoxide/polyvinylpyrrolidone (Ti(Bu)/PVP) fibers prepared by forcespinning to decompose and oxidize the base polymer and precursor. The obtained fibers were characterized by changes in chemical bonds on the surface using Fourier Transform Infrared Spectroscopy (FTIR), chemical composition by using Energy-Dispersive X-Ray Spectroscopy (EDX), X-ray Photoelectron Spectroscopy (XPS). The morphology of fibers was investigated by Scanning Electron Microscopy (SEM). A significant decrease of organic components was reached by short plasma exposure times less than 1 h. The obtained fibers exhibit a high surface porosity without degradation of the fibrous structure. The results obtained indicate that atmospheric pressure plasma assisted calcination can be a viable low-temperature, energy- and time-saving alternative or pre-treatment method for the conventional high-temperature thermal calcination.

  14. Reduced graphene oxide modified NiFe-calcinated layered double hydroxides for enhanced photocatalytic removal of methylene blue

    Science.gov (United States)

    Zhao, Guoqing; Li, Caifeng; Wu, Xia; Yu, Jingang; Jiang, Xinyu; Hu, Wenjihao; Jiao, Feipeng

    2018-03-01

    Calcined layered double hydroxides (CLDH) are one of the remarkable photocatalysts passionately studied for photodecolorization of organic dyes. NiFe-CLDH was successfully modified by reduced graphene oxide (RGO) through a facile in situ crystallization technique. The obtained RGO/NiFe-CLDH composites were fully characterized by powder X-ray diffraction (XRD), Scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), Fourier transform infrared (FT-IR), and UV-vis diffuse reflectance spectroscopy (DRS). The results analysis indicated that RGO sheets could work as base course to prompt the growth of LDH crystallites and NiFe-LDH lamellar crystal promiscuously distributed on the sheets with a strong interplay between each other. The photocatalytic performance of RGO/NiFe-CLDH composites toward decolorization of methylene blue tightly depended on the mass fraction of RGO and calcinated temperature. At the RGO weight loading of 1%, calcination temperature of 500 °C, the photocatalytic degradation efficiency of RGO/NiFe-CLDH composites reached 93.0% within 5.0 h. The enhanced activity of RGO/NiFe-CLDH composites may be due to the concerted catalysis effect between two constituents of as-prepared composites.

  15. Kinetics and equilibrium studies for the adsorption of Acid Red 57 from aqueous solutions onto calcined-alunite.

    Science.gov (United States)

    Tunali, Sibel; Ozcan, A Safa; Ozcan, Adnan; Gedikbey, Tevfik

    2006-07-31

    The adsorption of Acid Red 57 (AR57) onto calcined-alunite was examined in aqueous solution in a batch system with respect to contact time, pH and temperature. The first-order, pseudo-second-order kinetic and the intraparticle diffusion models were used to describe the kinetic data and the rate constants were evaluated. The experimental data fitted very well the pseudo-second-order kinetic model and also followed the intraparticle diffusion model up to 90 min. The Langmuir and Freundlich adsorption models were applied to describe the equilibrium isotherms and the isotherm constants were also determined. The equilibrium data are successfully fitted to the Langmuir adsorption isotherm. The Langmuir isotherm constant, K(L), was used to evaluate the changes of free energy, enthalpy and entropy of adsorption for the adsorption of AR57 onto calcined-alunite. The results indicate that calcined-alunite could be employed as low-cost material for the removal of acid dyes from textile effluents.

  16. Effects of Calcination Temperature on Preparation of Boron-Doped TiO2 by Sol-Gel Method

    Directory of Open Access Journals (Sweden)

    Wenjie Zhang

    2012-01-01

    Full Text Available Boron-doped TiO2 photocatalyst was prepared by a modified sol-gel method. Being calcinated at temperatures from 300°C to 600°C, all the 3% B-TiO2 samples presented anatase TiO2 phase, and TiO2 crystallite sizes were calculated to be 7.6, 10.3, 13.6, and 27.3 nm, respectively. The samples were composed of irregular particles with rough surfaces in the size range within 3 μm. Ti atoms were in an octahedron skeleton and existed mainly in the form of Ti4+, while the Ti-O-B structure was the main boron existing form in the 3% B-TiO2 sample. When calcination temperature increased from 300°C to 600°C, specific surface area decreased sharply from 205.6 m2/g to 31.8 m2/g. The average pore diameter was 10.53 nm with accumulative pore volume of 0.244 mL/g for the 3% B-TiO2 sample calcinated at 400°C, which performed optimal photocatalytic degradation activity. After 90 min of UV-light irradiation, degradation rate of methyl orange was 96.7% on the optimized photocatalyst.

  17. Application of calcined waste fish (Labeo rohita) scale as low-cost heterogeneous catalyst for biodiesel synthesis.

    Science.gov (United States)

    Chakraborty, R; Bepari, S; Banerjee, A

    2011-02-01

    This paper explores the feasibility of converting waste Rohu fish (Labeo rohita) scale into a high-performance, reusable, low-cost heterogeneous catalyst for synthesis of biodiesel from soybean oil. The thermo-gravimetric analysis (TGA) and X-ray diffraction (XRD) analysis revealed that a significant portion of the main component of fish scale i.e. HAP (hydroxyapatite) could be transformed into β-tri-calcium phosphate when calcined above 900°C for 2 h. Scanning Electron Microscopy (SEM) morphology studies of the calcined scale depicted a fibrous layer of porous structure; while a BET surface area of 39 m(2)/g was measured. Response surface methodology (RSM) was employed to determine the optimal parametric conditions viz. methanol/oil molar ratio, 6.27:1, calcination temperature, 997.42°C and catalyst concentration, 1.01 wt.% of oil corresponding to a maximum FAME yield of 97.73%. Reusability results confirmed that the prepared catalyst could be reemployed up to six times, procreating a potentially applicable avenue in biodiesel synthesis. Copyright © 2010 Elsevier Ltd. All rights reserved.

  18. Calcined Eggshell Waste for Mitigating Soil Antibiotic-Resistant Bacteria/Antibiotic Resistance Gene Dissemination and Accumulation in Bell Pepper.

    Science.gov (United States)

    Ye, Mao; Sun, Mingming; Feng, Yanfang; Li, Xu; Schwab, Arthur P; Wan, Jinzhong; Liu, Manqiang; Tian, Da; Liu, Kuan; Wu, Jun; Jiang, Xin

    2016-07-13

    The combined accumulation of antibiotics, heavy metals, antibiotic-resistant bacteria (ARB)/antibiotic resistance genes (ARGs) in vegetables has become a new threat to human health. This is the first study to investigate the feasibility of calcined eggshells modified by aluminum sulfate as novel agricultural wastes to impede mixed contaminants from transferring to bell pepper (Capsicum annuum L.). In this work, calcined eggshell amendment mitigated mixed pollutant accumulation in bell pepper significantly, enhanced the dissipation of soil tetracycline, sulfadiazine, roxithromycin, and chloramphenicol, decreased the water-soluble fractions of antibiotics, and declined the diversity of ARB/ARGs inside the vegetable. Moreover, quantitative polymerase chain reaction analysis detected that ARG levels in the bell pepper fruits significantly decreased to 10(-10) copies/16S copies, indicating limited risk of ARGs transferring along the food chain. Furthermore, the restoration of soil microbial biological function suggests that calcined eggshell is an environmentally friendly amendment to control the dissemination of soil ARB/ARGs in the soil-vegetable system.

  19. Maximizing Sustainability of Concrete through the Control of Moisture Rise and Drying Shrinkage Using Calcined Clay Pozzolan

    Directory of Open Access Journals (Sweden)

    John Solomon Ankrah

    2016-01-01

    Full Text Available The Ghanaian concrete industry is really a booming industry due to many infrastructural developments and the surge in residential development. However, many developmental projects that utilize concrete do suffer from the negative impact of moisture rise including paint peeling-off, bacterial and fungi growth, and microcracks as well as unpleasant looks on buildings. Such negative outlook resulting from the effects of moisture rise affects the longevity of concrete and hence makes concrete less sustainable. This study seeks to develop materials that could minimize the rise of moisture or ions through concrete medium. The experimental works performed in this study included pozzolanic strength activity index, water sorptivity, and shrinkage test. Calcined clay produced from clay was used as pozzolan to replace Portland cement at 20%. The strength activity test showed that the cement containing the calcined material attained higher strength activity indices than the control. The thermal gravimetric analysis showed that the pozzolan behaved partly as a filler material and partly as a pozzolanic material. The sorptivity results also showed that the blended mix resulted in lower sorptivity values than the control mortar. The study recommends that calcined clay and Portland cement mixtures could be used to produce durable concrete to maximize sustainability.

  20. Orthogonal flexible Rydberg aggregates

    Science.gov (United States)

    Leonhardt, K.; Wüster, S.; Rost, J. M.

    2016-02-01

    We study the link between atomic motion and exciton transport in flexible Rydberg aggregates, assemblies of highly excited light alkali-metal atoms, for which motion due to dipole-dipole interaction becomes relevant. In two one-dimensional atom chains crossing at a right angle adiabatic exciton transport is affected by a conical intersection of excitonic energy surfaces, which induces controllable nonadiabatic effects. A joint exciton-motion pulse that is initially governed by a single energy surface is coherently split into two modes after crossing the intersection. The modes induce strongly different atomic motion, leading to clear signatures of nonadiabatic effects in atomic density profiles. We have shown how this scenario can be exploited as an exciton switch, controlling direction and coherence properties of the joint pulse on the second of the chains [K. Leonhardt et al., Phys. Rev. Lett. 113, 223001 (2014), 10.1103/PhysRevLett.113.223001]. In this article we discuss the underlying complex dynamics in detail, characterize the switch, and derive our isotropic interaction model from a realistic anisotropic one with the addition of a magnetic bias field.

  1. One-step calcination-free synthesis of multicomponent spinel assembled microspheres for high-performance anodes of li-ion batteries: a case study of MnCo(2)O(4).

    Science.gov (United States)

    Fu, Chaochao; Li, Guangshe; Luo, Dong; Huang, Xinsong; Zheng, Jing; Li, Liping

    2014-02-26

    Multicomponent spinel metal-oxide assembled mesoporous microspheres, promising anode materials for Li-ion batteries with superior electrochemical performance, are usually obtained using different kinds of precursors followed by high-temperature post-treatments. Nevertheless, high-temperature calcinations often cause primary particles to aggregate and coarsen, which may damage the assembled microsphere architectures, leading to deterioration of electrochemical performance. In this work, binary spinel metal-oxide assembled mesoporous microspheres MnCo2O4 were fabricated by one-step low-temperature solvothermal method through handily utilizing the redox reaction of nitrate and ethanol. This preparation method is calcination-free, and the resulting MnCo2O4 microspheres were surprisingly assembled by nanoparticles and nanosheets. Two kinds of MnCo2O4 crystal nucleus with different exposed facet of (1̅10) and (11̅2̅) could be responsible for the formation of particle-assembled and sheet-assembled microspheres, respectively. Profiting from the self-assembly structure with mesoporous features, MnCo2O4 microspheres delivered a high reversible capacity up to 722 mAh/g after 25 cycles at a current density of 200 mA/g and capacities up to 553 and 320 mAh/g after 200 cycles at a higher current density of 400 and 900 mA/g, respectively. Even at an extremely high current density of 2700 mA/g, the electrode still delivered a capacity of 403 mAh/g after cycling with the stepwise increase of current densities. The preparation method reported herein may provide hints for obtaining various advanced multicomponent spinel metal-oxide assembled microspheres such as CoMn2O4, ZnMn2O4, ZnCo2O4, and so on, for high-performance energy storage and conversion devices.

  2. Effect of calcination temperature on the structure and catalytic performance of 80Ni20CO/SiO2 catalyst for CO2 methanation

    Science.gov (United States)

    Md Ali, S. A.; Hamid, K. H. K.; Ismail, K. N.

    2017-09-01

    The 80Ni20Co/SiO2 catalysts prepared using co-precipitate and incipient wetness impregnation method were used for production of methane through CO2 methanation reaction between CO and H2 gases. The effect of a range of calcination temperature on the structure and catalytic performance of 80Ni20Co/SiO2 catalyst was investigated using microactivity fixed bed reactor. It was found that the catalyst calcined at 400°C for 4.5 h under air atmosphere has shown the best catalytic performance for CO2 methanation. Characterization of 80Ni20Co/SiO2 catalyst calcined fresh samples was carried out using TPR-H2 analysis, Brunauere Emmette Teller (BET) measurements and X-ray diffraction (XRD. It was observed that calcination temperature influenced the structure, morphology and catalytic performance of the catalysts.

  3. Biocompatibility of calcined mesoporous silica particles with ventricular myocyte structure and function.

    Science.gov (United States)

    Aburawi, Elhadi H; Qureshi, Mohammed Anwar; Oz, Deniz; Jayaprakash, Petrilla; Tariq, Saeed; Hameed, Rashed S; Das, Sayantani; Goswami, Anandarup; Biradar, Ankush V; Asefa, Tewodros; Souid, Abdul-Kader; Adeghate, Ernest; Howarth, Frank Christopher

    2013-01-18

    In vivo and in vitro systems were employed to investigate the biocompatibility of two forms of calcined mesoporous silica microparticles, MCM41-cal and SBA15-cal, with ventricular myocytes. These particles have potential clinical use in delivering bioactive compounds to the heart. Ventricular myocytes were isolated from 6 to 8 week male Wistar rats. The distribution of the particles in ventricular myocytes was investigated by transmission electron microscopy and scanning electron microscopy. The distribution of particles was also examined in cardiac muscle 10 min after intravenous injection of 2.0 mg/mL MCM41-cal. Myocyte shortening and the Ca(2+) transient were determined following exposure to 200 μg/mL MCM41-cal or SBA15-cal for 10 min. Within 10 min of incubation at 25 °C, both MCM41-cal and SBA15-cal were found attached to the plasma membrane, and some particles were observed inside ventricular myocytes. MCM41-cal was more abundant inside the myocytes than SBA15-cal. The particles had a notable affinity to mitochondrial membranes, where they eventually settled. Within 10 min of intravenous injection (2.0 mg/mL), MCM41-cal traversed the perivascular space, and some particles entered ventricular myocytes and localized around the mitochondrial membranes. The amplitude of shortening was slightly reduced in myocytes superperfused with MCM41-cal or SBA15-cal. The amplitude of the Ca(2+) transient was significantly reduced in myocytes superperfused with MCM41-cal but was only slightly reduced with SBA15-cal. Overall, the results show reasonable bioavailability and biocompatibility of MCM41-cal and SBA15-cal with ventricular myocytes.

  4. Synthesis and crystal structure of As-synthesized and calcined pure silica zeolite ITQ-12.

    Science.gov (United States)

    Yang, Xiaobo; Camblor, Miguel A; Lee, Yongjae; Liu, Haiming; Olson, David H

    2004-08-25

    The small-pore pure silica zeolite ITQ-12 has been synthesized with fumed silica as the silica source in the presence of 1,3,4-trimethylimidazolium hydroxide and hydrofluoric acid under hydrothermal conditions at 448 K. Rietveld refinement using synchrotron X-ray diffraction data of the calcined ITQ-12 product taken at 298 K confirms the proposed topology, framework type code ITW, which can be described by a monoclinic unit cell [Si(24)O(48)] having Cm symmetry. Unit cell parameters are a = 10.3360(4), b = 15.0177(6), and c = 8.8639(4) A, beta = 105.356(3) degrees, and cell volume V = 1326.76(9) A(3). For as-synthesized ITQ-12, the occluded fluoride anion is located inside the double four-membered ring, while the flat 1,3,4-trimethylimidazolium cation lies on the equatorial plane of the slit-shaped [4(4)5(4)6(4)8(4)] cage, with its longest dimension in the [010] direction. The monoclinic unit cell |(C(6)N(2)H(11))(+)(2)F(-)(2)|[Si(24)O(48)], having Cm symmetry, has parameters a = 10.4478(3), b = 14.9854(4), and c = 8.8366(3) A, beta = 105.935(2) degrees, and cell volume V = 1330.34(7) A(3) at 298 K. Cooperative structure-directing effects during the crystallization of ITQ-12 are discussed in terms of the structure of the as-made material.

  5. Distinguishing aggregate formation and aggregate clearance using cell-based assays

    NARCIS (Netherlands)

    Eenjes, E. (Evelien); Dragich, J.M. (Joanna M.); H. Kampinga (Harm); Yamamoto, A. (Ai)

    2016-01-01

    textabstractThe accumulation of ubiquitylated proteinaceous inclusions represents a complex process, reflecting the disequilibrium between aggregate formation and aggregate clearance. Although decreasing aggregate formation or augmenting aggregate clearance will ultimately lead to a diminished

  6. Catalyst used in 1,2-epoxyalkane preparation is obtained by heating tetraalkyl ammonium salts, tetraalkyl siloxanes and amines, calcining and treating with a tetraalkoxy compound

    DEFF Research Database (Denmark)

    2001-01-01

    NOVELTY - The catalyst, used in 1,2-epoxyalkane preparation, is obtained by heat treating an aqueous composition comprising tetraalkyl ammonium salts, tetraalkyl siloxanes and amines, removing the template by calcining and treating with a tetraalkoxy compound......NOVELTY - The catalyst, used in 1,2-epoxyalkane preparation, is obtained by heat treating an aqueous composition comprising tetraalkyl ammonium salts, tetraalkyl siloxanes and amines, removing the template by calcining and treating with a tetraalkoxy compound...

  7. Sintering and reactivity of CaCO{sub 3}-based sorbents for in situ CO{sub 2} capture in fluidized beds under realistic calcination conditions

    Energy Technology Data Exchange (ETDEWEB)

    Lu, D.Y.; Hughes, R.W.; Anthony, E.J.; Manovic, V. [Natural Resources Canada, Ottawa, ON (Canada)

    2009-06-15

    Sintering during calcination/carbonation may introduce substantial economic penalties for a CO{sub 2} looping cycle using limestone/dolomite-derived sorbents. Cyclic carbonation and calcination reactions were investigated for CO{sub 2} capture under fluidized bed combustion (FBC) conditions. The cyclic carbonation characteristics of CaCO{sub 3}-derived sorbents were compared at various calcination temperatures (700-925{sup o} C) and different gas stream compositions: pure -2 and a realistic calciner environment where high concentrations of CO{sub 2}>80-90% are expected. The conditions during carbonation were 700 {sup o}C and 15% CO{sub 2} in N{sub 2} and 0.18% or 0.50% SO{sub 2} in selected tests. Up to 20 calcination/carbonation cycles were conducted using a thermogravimetric analyzer (TGA) apparatus. Three Canadian limestones were tested: Kelly Rock, Havelock, and Cadomin, using a prescreened particle size range of 400-650 {mu} m. Calcined Kelly Rock and Cadomin samples were hydrated by steam and examined. Sorbent reactivity was reduced whenever SO{sub 2} was introduced to either the calcining or carbonation streams. The multicyclic capture capacity of CaO for CO{sub 2} was substantially reduced at high concentrations of CO{sub 2} during the sorbent regeneration process and carbonation conversion of the Kelly Rock sample obtained after 20 cycles was only 10.5%. Hydrated sorbents performed better for CO{sub 2} capture but showed deterioration following calcination in high CO{sub 2} gas streams indicating that high CO{sub 2} and SO{sub 2} levels in the gas stream lead to lower CaO conversion because of enhanced sintering and irreversible formation of CaSO{sub 4}.

  8. Radiant-heat spray-calcination process for the solid fixation of radioactive waste. Part 1, Non-radioactive pilot unit

    Energy Technology Data Exchange (ETDEWEB)

    Allemann, R.T.; Johnson, B.M. Jr.

    1960-11-14

    The fixation of radioactive waste in a stable solid media by means of calcination of these aqueous solutions has been the subject of considerable-effort throughout the U. S. Atomic Energy Commission and by atomic energy organizations in other countries. Several methods of doing this on a continuous or semi-continuous basis have been devised, and a fev have been demonstrated to be feasible for the handling of non-radioactive, or low-activity, simulated wastes. Notable among methods currently under development are: (a) batch-operated pot calcination of waste generated from reprocessing stainless steel clad fuel elements (Darex process) and Purex waste, (b) combination rotary kiln and ball mill calcination of aluminum nitrate (TBP-25 and Redox process), and (c) fluidized bed calcination of TBP-25 and Purex wastes. Although a considerable amount of engineering experience has been obtained on the calcination of dissolved salts in a fluidized bed, and the other methods have been the subjects of a great deal of study, none of them have been developed to-the extent which would rule out the desirability of further investigation of other possible methods of calcination.

  9. Preparation and Characterization of Au/Pd Modified-TiO2 Photocatalysts for Phenol and Toluene Degradation under Visible Light—The Effect of Calcination Temperature

    Directory of Open Access Journals (Sweden)

    Anna Cybula

    2014-01-01

    Full Text Available Rutile loaded with Au/Pd nanoparticles was prepared using a water-in-oil microemulsion system of water/AOT/cyclohexane followed by calcination. The effect of calcination temperature (from 350 to 700°C on the structure of Au/Pd nanoparticles deposited at rutile matrix and the photocatalytic properties of Au/Pd-TiO2 was investigated in two model reactions (toluene degradation in gas phase and phenol degradation in aqueous phase. Toluene was irradiated over Au/Pd-TiO2 using light emitting diodes (LEDs, λmax⁡ = 415 nm. The sample 0.5 mol% Pd/TiO2 exhibited the highest activity under visible light irradiation in gas and aqueous phase reaction among all photocatalysts calcined at 350°C, while the sample modified only with gold nanoparticles showed the lowest activity. The Au/Pd-TiO2 sample calcinated at 350°C possesses the highest photocatalytic activity when degrading phenol under visible light, which is 14 times higher than that of the one calcinated at 450°C. It was observed that increasing temperature from 350 to 700°C during calcination step caused segregation of metals and finally resulted in photoactivity drop.

  10. Characterization of Boron Atom Aggregation

    National Research Council Canada - National Science Library

    Maier, John P

    2005-01-01

    ... in matrices ranging from neon to those doped with hydrogen. The studies of the aggregation properties were hampered by the lack of spectroscopic knowledge on the electronic transitions of the polyatomic boron molecules and their ions...

  11. Aggregated Computational Toxicology Resource (ACTOR)

    Science.gov (United States)

    The Aggregated Computational Toxicology Resource (ACTOR) is a database on environmental chemicals that is searchable by chemical name and other identifiers, and by chemical structure. This information is consolidated from more than 200 publicly available sources of data.

  12. Effects of doping amounts of potassium ferricyanide with titanium dioxide and calcination durations on visible-light degradation of pharmaceuticals.

    Science.gov (United States)

    Lin, Justin Chun-Te; de Luna, Mark Daniel G; Gotostos, Mary Jane N; Lu, Ming-Chun

    2016-11-01

    Acetaminophen (ACT) is one of the most frequently detected pharmaceuticals in aqueous environments, and treatment of ACT were generally carried out by photocatalytic degradations under high energy UV irradiation. In this study, potassium ferricyanide was utilized as a quadruple-elemental dopant in a TiO2 photocatalyst in order to enhance its visible-light activity. Two critical parameters (amounts of dopants and durations of calcination) of the synthesis of the photocatalyst by a sol-gel method were systematically evaluated. Crystal structure of the doping TiO2 was examined by X-ray diffraction while the effects of the two parameters on the photocatalytic activity were elucidated by various characterizations. Increasing the amount of dopant or the duration of calcination red-shifted the UV-vis DRS of the doped TiO2. The estimated band gap energy of the doped TiO2 decreased slightly as the amount of dopant increased, but it increased as the duration of calcination increased. The FT-IR yielded characteristic peaks that revealed the effects of the two parameters, whereas the SEM images revealed the morphological evolutions of each effect. The photocatalyst, synthesized at optimum conditions was able to remove 99.1 % acetaminophen with rate constant of 7.9 × 10(-3) min(-1), which was 4.88 times greater than virgin TiO2. In general, this study not only optimized synthetic conditions of the new visible-light active photocatalyst for ACT degradation but also presented characterizations conducted by SEM, XRD, UV-vis DRS, and FTIR to elucidate the relationship between modified structure and the photocatalytic activity. Graphical abstract Effects of doping amounts of K3[Fe(CN)6] and calcunation duration on visible light absorbance of TiO2 photocatalysts.

  13. [Enhanced visible-light absorbance of nanosized AgI/TiO2 by using calcination combined with light irradiation].

    Science.gov (United States)

    Liang, Zhu; Ni, Jin-Ren

    2009-07-15

    With the aim to enhance visible-light absorbance, calcination combined with light irradiation was used to modify nanosized AgI/TiO2. UV-Vis spectrum curves indicated that the modified sample exhibited an intense absorption in the whole visible light range and a spectrum shifted from 465 nm to 800 nm, and that absorbance at 500 nm was improved three times as much as that of the reported pertinent material. XRD analytic results demonstrated that calcined AgI/TiO2 possessed more rutile phase with reduced band gap from 2.89 eV to 2.81 eV, and that the following xenon-light irradiation further enhanced the relative contents of anatase TiO2, rutile TiO2 and AgI accompanied with produced AgCl phase, leading to the decrease in band gap to 1.55 eV. Formation of AgCl and increases in the relative contents of rutile TiO2 and AgI should take the main responsibilities for the decrease in the band gap and enlargement of visible-light absorbance. Additionally, it was confirmed that only the spectrum absorption of the calcined AgI/TiO2 could be improved by light irradiation, and that ultraviolet light played more role than visible part during the light irradiation. Moreover, it was proposed here that two or more silver halides supported on TiO2 could show more capabilities to stimulate visible-light activation of TiO2.

  14. Sorption behaviour of manganese-coated calcined-starfish and manganese-coated sand for Mn(II).

    Science.gov (United States)

    Lee, Seung-Mok; Kim, Won-Gee; Yang, Jae-Kyu; Tiwari, Diwakar

    2010-04-01

    The objective of the present investigation was to explore the sorption behaviour of manganese-coated samples of calcined starfish (MCCSF) (i.e. the impregnation of calcined starfish with manganese) for the removal of low levels of an important heavy metal toxic ion, Mn(II), from aqueous solutions. The suitability of this solid was further compared with two different samples of manganese-coated sands (MCS): MCS4 and MCS9 impregnated at pH 4.0 and pH 9.0, respectively. These comparative studies were performed in both batch and column experiments. Batch data indicated that a fairly good stability of the coating was obtained for these three samples in the pH region 2.5 to 10.0. The removal efficiency of MCCSF was fairly good in comparison with the MCS4 and MCS9 samples. These last two samples possessed similar Mn(II) removal capacities. Moreover, a small dose of sodium hypochlorite further enhanced the uptake of Mn(II) by these solids. The sorbate concentration dependence data fitted reasonably well to the Freundlich adsorption isotherm. The column data indicated that MCCSF possessed a relatively higher adsorption capacity compared with the MCS4 and MCS9 samples. The breakthrough curves obtained were then used to evaluate the apparent removal capacity of these solids under the dynamic conditions using the Thomas equation. The SEM images obtained for these manganese-coated solids along with the virgin base materials, i.e. sand and calcined starfish, showed that manganese oxides occupied the surfaces or pores of the base materials and formed clusters on the base surface.

  15. Adsorption of a cationic dye (Yellow Basic 28 ontothe calcined mussel shells: Kinetics, Isotherm and Thermodynamic Parameters

    Directory of Open Access Journals (Sweden)

    Imane EL Ouahabi

    2015-11-01

    Full Text Available The aim of this study is to valorise the mussel shells and evaluate the adsorption capacity of calcined mussel shells for the cationic dyes.  The adsorbent was characterized by DRX, FTIR, BET and SEM, respectively. The adsorption of Yellow Basic28 on calcined mussel shells was investigated using the parameters such as concentrations (10-50mg/L, pH (3-10, ionic strength (0-2 mol / L and temperature (288 - 318 °C.  The adsorption rate data were analysed according to the first and second-order kinetic models.  The adsorption kinetics was found to be best represented by the pseudo-second-order kinetic model.  The experimental isotherm data were analyzed using Langmuir, Freundlich, Temkin, Elovich and Dubinin–Radushkevich isotherm equations on the dye-adsorbent system. The experimental data yielded excellent fits with Freundlich isotherm equation (R² = 0.966. It was indicative of the heterogeneity of the adsorption sites on the CMS particles.  Various thermodynamic parameters such as enthalpy of adsorption ΔH°, free energy change ΔG°and entropy ΔS° were estimated.  The positive value of ΔH°(30.321 kJ/mol and negative values of ΔG° (from -5.392 to -2.873 kJ/mol show the process is endothermic and spontaneous.  The negative value of entropy ΔS° (-87.172 J/mol K suggest the decreased randomness at the solid-liquid interface during the adsorption of dyes onto calcined mussel shells.

  16. Effect of calcination temperature on the photodegradation efficiency of Ni/ZnO composite in removal of organic dye

    Science.gov (United States)

    Thein, Myo Thuya; Pung, Swee-Yong; Aziz, Azizan; Lockman, Zainovia; Itoh, Mitsuru

    2017-07-01

    ZnO based composite is an attractive UV light driven semiconductor photocatalyst to degrade organic compounds attributed to its wide bandgap (3.37 eV). In this study, Ni/ZnO composites were synthesized via solution precipitation method. The composites were calcinated at various temperature, i.e. from 250 °C to 700 °C and subsequently annealed at 500°C in reductive environment (hydrogen atmosphere). The diffraction peaks of all samples could be indexed to the hexagonal wurtzite ZnO. No diffraction peaks from Ni could be observed in all samples, suggesting that the amount of Ni in the composites were below the detection limit of X-ray diffraction (XRD). The field emission scanning electron microscope (FESEM) images confirm that all samples were rod-like structure with hexagonal tips. In addition, small Ni particles were homogeneously deposited on the surface of ZnO rods. This observation is supported by energy dispersive X-ray spectroscopy (EDX) analysis, showing present of Zn, O and Ni elements. It is noted that ZnO rods coupled with Ni experienced quenching of visible emission and enhancing of UV emission in room temperature photoluminescence (RTPL) analysis. The photodegradation efficiency of Ni/ZnO rods was improved when a higher calcination temperature was used. The removal of RhB dye under UV light (352 nm) by these photocatalysts followed pseudo first-order kinetic reaction. The Ni/ZnO composites synthesized at calcination temperature of 500 °C demonstrated the highest photodegradation efficiency of 37 % and the largest rate constant of 0.0053 min-1 after 75 min UV irradiation.

  17. Page 1 12 S R Sawant and R N Patil Fe2O3 were calcinated at 700 ...

    Indian Academy of Sciences (India)

    Fe2O3 were calcinated at 700°C for 24 hr. Powders of these oxides were fired to. 950°C for 24 hr and furnace cooled at the rate of 80°Chr. Pellets of 1 cm diameter and 2 mm thickness were prepared and sintered at a temperature 950°C for 8 hr and furnace cooled at the rate of 80°C/hr. Retaining a series of. Cu, Zn;– Fe3O4 ...

  18. Arsenic removal from aqueous solutions using Fe3O4-HBC composite: effect of calcination on adsorbents performance.

    Directory of Open Access Journals (Sweden)

    Shams Ali Baig

    Full Text Available The presence of elevated concentration of arsenic in water sources is considered to be health hazard globally. Calcination process is known to change the surface efficacy of the adsorbent. In current study, five adsorbent composites: uncalcined and calcined Fe3O4-HBC prepared at different temperatures (400°C and 1000°C and environment (air and nitrogen were investigated for the adsorptive removal of As(V and As(III from aqueous solutions determining the influence of solution's pH, contact time, temperature, arsenic concentration and phosphate anions. Characterizations from FTIR, XRD, HT-XRD, BET and SEM analyses revealed that the Fe3O4-HBC composite at higher calcination temperature under nitrogen formed a new product (fayalite, Fe2SiO4 via phase transformation. In aqueous medium, ligand exchange between arsenic and the effective sorbent site ( = FeOOH was established from the release of hydroxyl group. Langmuir model suggested data of the five adsorbent composites follow the order: Fe3O4-HBC-1000°C(N2>Fe3O4-HBC (uncalcined>Fe3O4-HBC-400°C(N2>Fe3O4-HBC-400°C(air>Fe3O4-HBC-1000°C(air and the maximum As(V and As(III adsorption capacities were found to be about 3.35 mg g(-1 and 3.07 mg g(-1, respectively. The adsorption of As(V and As(III remained stable in a wider pH range (4-10 using Fe3O4-HBC-1000°C(N2. Additionally, adsorption data fitted well in pseudo-second-order (R2>0.99 rather than pseudo-first-order kinetics model. The adsorption of As(V and As(III onto adsorbent composites increase with increase in temperatures indicating that it is an endothermic process. Phosphate concentration (0.0l mM or higher strongly inhibited As(V and As(III removal through the mechanism of competitive adsorption. This study suggests that the selective calcination process could be useful to improve the adsorbent efficiency for enhanced arsenic removal from contaminated water.

  19. Fractal Aggregates in Tennis Ball Systems

    Science.gov (United States)

    Sabin, J.; Bandin, M.; Prieto, G.; Sarmiento, F.

    2009-01-01

    We present a new practical exercise to explain the mechanisms of aggregation of some colloids which are otherwise not easy to understand. We have used tennis balls to simulate, in a visual way, the aggregation of colloids under reaction-limited colloid aggregation (RLCA) and diffusion-limited colloid aggregation (DLCA) regimes. We have used the…

  20. A Functional Reference Architecture for Aggregators

    DEFF Research Database (Denmark)

    Bondy, Daniel Esteban Morales; Heussen, Kai; Gehrke, Oliver

    2015-01-01

    Aggregators are considered to be a key enabling technology for harvesting power system services from distributed energy resources (DER). As a precondition for more widespread use of aggregators in power systems, methods for comparing and validating aggregator designs must be established. This paper...... proposes a functional reference architecture for aggregators to address this requirement....

  1. Aggregated Recommendation through Random Forests

    Directory of Open Access Journals (Sweden)

    Heng-Ru Zhang

    2014-01-01

    Full Text Available Aggregated recommendation refers to the process of suggesting one kind of items to a group of users. Compared to user-oriented or item-oriented approaches, it is more general and, therefore, more appropriate for cold-start recommendation. In this paper, we propose a random forest approach to create aggregated recommender systems. The approach is used to predict the rating of a group of users to a kind of items. In the preprocessing stage, we merge user, item, and rating information to construct an aggregated decision table, where rating information serves as the decision attribute. We also model the data conversion process corresponding to the new user, new item, and both new problems. In the training stage, a forest is built for the aggregated training set, where each leaf is assigned a distribution of discrete rating. In the testing stage, we present four predicting approaches to compute evaluation values based on the distribution of each tree. Experiments results on the well-known MovieLens dataset show that the aggregated approach maintains an acceptable level of accuracy.

  2. Channel Aggregation Schemes for Cognitive Radio Networks

    Science.gov (United States)

    Lee, Jongheon; So, Jaewoo

    This paper proposed three channel aggregation schemes for cognitive radio networks, a constant channel aggregation scheme, a probability distribution-based variable channel aggregation scheme, and a residual channel-based variable channel aggregation scheme. A cognitive radio network can have a wide bandwidth if unused channels in the primary networks are aggregated. Channel aggregation schemes involve either constant channel aggregation or variable channel aggregation. In this paper, a Markov chain is used to develop an analytical model of channel aggregation schemes; and the performance of the model is evaluated in terms of the average sojourn time, the average throughput, the forced termination probability, and the blocking probability. Simulation results show that channel aggregation schemes can reduce the average sojourn time of cognitive users by increasing the channel occupation rate of unused channels in a primary network.

  3. Customer Aggregation: An Opportunity for Green Power?

    Energy Technology Data Exchange (ETDEWEB)

    Holt, E.; Bird, L.

    2001-02-26

    We undertook research into the experience of aggregation groups to determine whether customer aggregation offers an opportunity to bring green power choices to more customers. The objectives of this report, therefore, are to (1) identify the different types of aggregation that are occurring today, (2) learn whether aggregation offers an opportunity to advance sales of green power, and (3) share these concepts and approaches with potential aggregators and green power advocates.

  4. Hydrogen Production by Steam Reforming of Ethanol over Nickel Catalysts Supported on Sol Gel Made Alumina: Influence of Calcination Temperature on Supports.

    Science.gov (United States)

    Yaakob, Zahira; Bshish, Ahmed; Ebshish, Ali; Tasirin, Siti Masrinda; Alhasan, Fatah H

    2013-05-30

    Selecting a proper support in the catalyst system plays an important role in hydrogen production via ethanol steam reforming. In this study, sol gel made alumina supports prepared for nickel (Ni) catalysts were calcined at different temperatures. A series of (Ni/AlS.G.) catalysts were synthesized by an impregnation procedure. The influence of varying the calcination temperature of the sol gel made supports on catalyst activity was tested in ethanol reforming reaction. The characteristics of the sol gel alumina supports and Ni catalysts were affected by the calcination temperature of the supports. The structure of the sol gel made alumina supports was transformed in the order of γ → (γ + θ) → θ-alumina as the calcination temperature of the supports increased from 600 °C to 1000 °C. Both hydrogen yield and ethanol conversion presented a volcano-shaped behavior with maximum values of 4.3 mol/mol ethanol fed and 99.5%, respectively. The optimum values were exhibited over Ni/AlS.G800 (Ni catalyst supported on sol gel made alumina calcined at 800 °C). The high performance of the Ni/AlS.G800 catalyst may be attributed to the strong interaction of Ni species and sol gel made alumina which lead to high nickel dispersion and small particle size.

  5. New DC conductivity spectra of Zn–Al layered double hydroxide (Zn–Al–NO3–LDH and its calcined product of ZnO phase

    Directory of Open Access Journals (Sweden)

    Abdullah Ahmed Ali Ahmed

    2017-05-01

    Full Text Available Zn–Al–NO3–LDH nanostructure was synthesized via the coprecipitation method at molar ratio Zn2+/Al3+ = 4 and pH = 7. The resultant sample was thermally treated at calcined temperatures of 50, 100, 150, 200, 250 and 300 °C. The layered structure of the Zn–Al–NO3–LDH samples was stable below the calcination temperature 200 °C as shown in powder X-ray diffraction (PXRD patterns of calcined samples. The calcination products showed a collapse of LDH structure and ZnO phase was formed at 200 °C and above. The dielectric spectroscopy of LDH was explained using anomalous low frequency dispersion (ALFD due to the low mobility of LDH carriers. The conductivity spectra of LDH can be theoretically described according to the effective phase within the calcination products of LDH. In the comparison with previously researches, this study presented higher values of DC conductivity for all studied samples.

  6. Evaluation of blends bauxite-calcination-method red mud with other industrial wastes as a cementitious material: properties and hydration characteristics.

    Science.gov (United States)

    Zhang, Na; Liu, Xiaoming; Sun, Henghu; Li, Longtu

    2011-01-15

    Red mud is generated from alumina production, and its disposal is currently a worldwide problem. In China, large quantities of red mud derived from bauxite calcination method are being discharged annually, and its utilization has been an urgent topic. This experimental research was to evaluate the feasibility of blends red mud derived from bauxite calcination method with other industrial wastes for use as a cementitious material. The developed cementitious material containing 30% of the bauxite-calcination-method red mud possessed compressive strength properties at a level similar to normal Portland cement, in the range of 45.3-49.5 MPa. Best compressive strength values were demonstrated by the specimen RSFC2 containing 30% bauxite-calcination-method red mud, 21% blast-furnace slag, 10% fly ash, 30% clinker, 8% gypsum and 1% compound agent. The mechanical and physical properties confirm the usefulness of RSFC2. The hydration characteristics of RSFC2 were characterized by XRD, FTIR, (27)Al MAS-NMR and SEM. As predominant hydration products, ettringite and amorphous C-S-H gel are principally responsible for the strength development of RSFC2. Comparing with the traditional production for ordinary Portland cement, this green technology is easier to be implemented and energy saving. This paper provides a key solution to effectively utilize bauxite-calcination-method red mud. Copyright © 2010 Elsevier B.V. All rights reserved.

  7. SHAPE CHARACTERIZATION OF CONCRETE AGGREGATE

    Directory of Open Access Journals (Sweden)

    Jing Hu

    2011-05-01

    Full Text Available As a composite material, the performance of concrete materials can be expected to depend on the properties of the interfaces between its two major components, aggregate and cement paste. The microstructure at the interfacial transition zone (ITZ is assumed to be different from the bulk material. In general, properties of conventional concrete have been found favoured by optimum packing density of the aggregate. Particle size is a common denominator in such studies. Size segregation in the ITZ among the binder particles in the fresh state, observed in simulation studies by concurrent algorithm-based SPACE system, additionally governs density as well as physical bonding capacity inside these shell-like zones around aggregate particles. These characteristics have been demonstrated qualitatively pertaining also after maturation of the concrete. Such properties of the ITZs have direct impact on composite properties. Despite experimental approaches revealed effects of aggregate grain shape on different features of material structure (among which density, and as a consequence on mechanical properties, it is still an underrated factor in laboratory studies, probably due to the general feeling that a suitable methodology for shape characterization is not available. A scientific argument hindering progress is the interconnected nature of size and shape. Presently, a practical problem preventing shape effects to be emphasized is the limitation of most computer simulation systems in concrete technology to spherical particles. New developments at Delft University of Technology will make it possible in the near future to generate jammed states, or other high-density fresh particle mixtures of non-spherical particles, which thereupon can be subjected to hydration algorithms. This paper will sketch the outlines of a methodological approach for shape assessment of loose (non-embedded aggregate grains, and demonstrate its use for two types of aggregate, allowing

  8. Effects of Calcination Temperature and Acid-Base Properties on Mixed Potential Ammonia Sensors Modified by Metal Oxides

    Directory of Open Access Journals (Sweden)

    Kenichi Shimizu

    2011-02-01

    Full Text Available Mixed potential sensors were fabriated using yttria-stabilized zirconia (YSZ as a solid electrolyte and a mixture of Au and various metal oxides as a sensing electrode. The effects of calcination temperature ranging from 600 to 1,000 °C and acid-base properties of the metal oxides on the sensing properties were examined. The selective sensing of ammonia was achieved by modification of the sensing electrode using MoO3, Bi2O3 and V2O5, while the use of WO3, Nb2O5 and MgO was not effective. The melting points of the former group were below 820 °C, while those of the latter group were higher than 1,000 °C. Among the former group, the selective sensing of ammonia was strongly dependent on the calcination temperature, which was optimum around melting point of the corresponding metal oxides. The good spreading of the metal oxides on the electrode is suggested to be one of the important factors. In the former group, the relative response of ammonia to propene was in the order of MoO3 > Bi2O3 > V2O5, which agreed well with the acidity of the metal oxides. The importance of the acidic properties of metal oxides for ammonia sensing was clarified.

  9. A comparative study of thermal calcination and an alkaline hydrolysis method in the isolation of hydroxyapatite from Thunnus obesus bone

    Energy Technology Data Exchange (ETDEWEB)

    Venkatesan, Jayachandran; Ryu, BoMi; Thomas, Noel Vinay; Kim, Se Kwon [Department of Chemistry, Pukyong National University, Busan 608-737 (Korea, Republic of); Qian Zhongji, E-mail: sknkim@pknu.ac.kr [Marine Bioprocess Research Center, Pukyong National University, Busan 608-737 (Korea, Republic of)

    2011-06-15

    In the present study, hydroxyapatite (HAp) was isolated from Thunnus obesus bone using alkaline hydrolysis and thermal calcination methods. The obtained ceramic has been characterized by thermal gravimetric analysis (TGA), Fourier transform infrared spectroscopy (FT-IR), powder x-ray diffraction analysis (XRD), field-emission scanning electron microscopy, energy-dispersive x-ray analysis, transmission electron microscopy (TEM), selected area diffraction analysis, cytotoxic analysis and cell proliferation analysis. The results indicate that there are significant differences between the ceramics and T. obesus bone. FT-IR and TGA results affirmed that the collagen and organic moieties have been eliminated by both the proposed methods. XRD results were in agreement with JCPDS data. TEM and selective area diffraction images have signified that the thermal calcination method produces good crystallinity with dimensions 0.3-1.0 {mu}m, whereas the alkaline hydrolysis method produces nanostructured HAp crystals with 17-71 nm length and 5-10 nm width. Biocompatibility of HAp crystals was evaluated by cytotoxicity and cell proliferation with human osteoblast-like cell MG-63.

  10. Fabrication, optical properties and laser outputs of Nd:YAG ceramics based on laser ablated and pre-calcined powders

    Science.gov (United States)

    Osipov, V. V.; Maksimov, R. N.; Shitov, V. A.; Lukyashin, K. E.; Toci, G.; Vannini, M.; Ciofini, M.; Lapucci, A.

    2017-09-01

    Transparent Nd:YAG ceramic was fabricated by the solid-state reaction method with an additional round of pre-calcining using nanopowders of 1 at.% Nd:Y2O3 and Al2O3 synthesized by laser ablation. The pre-calcining step and addition of tetraethyl orthosilicate was found crucial for fabricating high optical quality Nd:YAG ceramic from such nanoparticles. The transmittance of the obtained 2-mm-thick Nd:YAG ceramic was 83.6% at the wavelength of 1064 nm, which is very close to the theoretical value. The uniformity of the optical quality of ceramic was mapped by analyzing the point-by-point transmission of a focused laser beam. The average volume of the scattering centers in the obtained ceramic was evaluated by direct count method to be 17 ppm. The Nd distribution was determined by fluorescence imaging to be homogeneous throughout the sample. Output power of 4.9 W with a slope efficiency of 52.7% was obtained in 1.5-mm-thick Nd:YAG ceramic under a quasi-continuous wave (QCW) laser diode end pumping at 805 nm.

  11. Adsorptive removal of 2,4,6-trichlorophenol in aqueous solution using calcined kaolinite-biomass composites.

    Science.gov (United States)

    Olu-Owolabi, Bamidele I; Alabi, Alimoh H; Diagboya, Paul N; Unuabonah, Emmanuel I; Düring, Rolf-Alexander

    2017-05-01

    Synergistically combined low-cost composites may be effective for the potential treatment of effluents containing organic pollutants. Hence, preparation of Carica-papaya-modified-kaolinite (CPK) and pine-cone-modified-kaolinite (PCK) composites via calcination of pure kaolinite (KAC), Carica-papaya and pine-cone seeds is demonstrated. The composites' specific surface areas were reduced by more than 57% but no structural modification in KAC lattice d-spacing, indicating impregnation of calcined biomass on clay surfaces and pores. However, composites' cation exchange capacities were enhanced over 4-fold, indicating higher potential for adsorption. Adsorption of 2,4,6-trichlorophenol on composites and KAC showed that CPK and PCK attained equilibrium relatively faster (30 min) compared to KAC (60 min). Modeling studies showed that 2,4,6-trichlorophenol removal mechanisms involved electrostatic interactions on sites of similar energy. Modification enhanced adsorption by 52 and 250% in PCK and CPK, respectively, and adsorption increased with temperature. Copyright © 2017 Elsevier Ltd. All rights reserved.

  12. Beneficiation of Low-Grade Phosphate Deposits by a Combination of Calcination and Shaking Tables: Southwest Iran

    Directory of Open Access Journals (Sweden)

    Shahram Shariati

    2015-06-01

    Full Text Available Three quarters of the world’s phosphate deposits are of sedimentary origin and 75%–80% of those include carbonate gangue. In this study, carbonate sedimentary phosphate deposits of the Lar Mountains of southwest Iran are studied. These deposits consist mainly of calcite, fluorapatite, quartz, kaolinite and illite, with an average P2O5 grade of 9%–10% (low-grade. Various pre-processing and processing methods have been developed for concentrating low-grade phosphate up to marketable grade and this study aims to select the optimal method to produce an economically viable grade of phosphate concentrate from low-grade ore. Different concentration methods, including calcination and gravity separation, were applied on samples at both a laboratory and semi-industrial scale (pilot scale. Using an integrated method of calcination (performed in a rotary kiln and shaking table for concentrating the low-grade phosphate ore, the results show promise at producing grades of 30.77% P2O5 with 60.7%–63.2% recovery.

  13. Removal of indigo carmine dye from water to Mg-Al-CO(3)-calcined layered double hydroxides.

    Science.gov (United States)

    El Gaini, L; Lakraimi, M; Sebbar, E; Meghea, A; Bakasse, M

    2009-01-30

    Layered double hydroxides (LDHs) calcined, denoted as CLDHs, have been shown to recover their original layered structure in the presence of appropriate anions. In the light of this so-called "memory effect", the removal of indigo carmine (IC), an anionic dye, from aqueous solution by calcined Mg-Al-CO(3) LDHs was investigated in batch mode. We looked at the influence of pH values, dye-adsorbent contact time, initial dye concentration and various temperatures of heating of LDHs on the decolorization rate of IC. The adsorption isotherms, described by Freundlich model are L-type. The characterization of the solids CLDHs, both fresh and after removal of IC, by X-ray diffraction and infrared spectroscopy shows that the IC adsorption on CLDHs is enhanced by reconstruction of a matrix hydrotalcite intercaled by the dye, and the intercalation of the organic ion was clearly evidenced by the net increase in the basal spacing from 0.76 nm for [Mg-Al-CO(3)] to 2.13 nm for the organic derivative.

  14. Removal of indigo carmine dye from water to Mg-Al-CO{sub 3}-calcined layered double hydroxides

    Energy Technology Data Exchange (ETDEWEB)

    El Gaini, L. [Faculty of Science, University Chouaib Doukkali, 24000 El Jadida (Morocco); Lakraimi, M. [ENS Ecole Normale Superieure, 40000 Marrakech (Morocco); Sebbar, E. [Faculty of Science, University Chouaib Doukkali, 24000 El Jadida (Morocco); Meghea, A. [University POLITEHNICA of Bucharest (Romania); Bakasse, M. [Faculty of Science, University Chouaib Doukkali, 24000 El Jadida (Morocco)], E-mail: bakassem@yahoo.fr

    2009-01-30

    Layered double hydroxides (LDHs) calcined, denoted as CLDHs, have been shown to recover their original layered structure in the presence of appropriate anions. In the light of this so-called 'memory effect', the removal of indigo carmine (IC), an anionic dye, from aqueous solution by calcined Mg-Al-CO{sub 3} LDHs was investigated in batch mode. We looked at the influence of pH values, dye-adsorbent contact time, initial dye concentration and various temperatures of heating of LDHs on the decolorization rate of IC. The adsorption isotherms, described by Freundlich model are L-type. The characterization of the solids CLDHs, both fresh and after removal of IC, by X-ray diffraction and infrared spectroscopy shows that the IC adsorption on CLDHs is enhanced by reconstruction of a matrix hydrotalcite intercaled by the dye, and the intercalation of the organic ion was clearly evidenced by the net increase in the basal spacing from 0.76 nm for [Mg-Al-CO{sub 3}] to 2.13 nm for the organic derivative.

  15. Effects of calcination temperature and heating rate on the photocatalytic properties of ZnO prepared by pyrolysis.

    Science.gov (United States)

    He, Lingling; Tong, Zhifang; Wang, Zhonghua; Chen, Ming; Huang, Ni; Zhang, Wei

    2018-01-01

    A series of ZnO nanorods were prepared by pyrolysis of zinc acetate at different calcination temperatures and heating rates under ambient atmosphere. The as-prepared ZnO nanorods were characterized by X-ray diffractometer (XRD), scanning electron microscopy (SEM), UV-visible diffuse reflectance spectroscopy (DRS) and X-ray photoelectron spectroscopy (XPS). The photocatalytic performances of the ZnO nanorods were evaluated by the photodegradation of methyl orange (MO) and 4-nitrophenol (4-NP). The morphology, optical property, surface composition, and photocatalytic performance of the ZnO samples were affected by both calcination temperature and heating rate. The photocatalytic activity of the ZnO sample was obviously decreased with increased heating rate, which might be ascribed to the simultaneous decrease of oxygen vacancies and surface adsorption oxygen species. The ZnO nanorods prepared at 300°C with a heating rate of 1°C/min exhibited good photocatalytic activity and photochemical stability, allowing good potential practical application in environmental remediation. Copyright © 2017 Elsevier Inc. All rights reserved.

  16. Heavy metal removal and speciation transformation through the calcination treatment of phosphorus-enriched sewage sludge ash.

    Science.gov (United States)

    Li, Rundong; Zhao, Weiwei; Li, Yanlong; Wang, Weiyun; Zhu, Xuan

    2015-01-01

    On the basis of the heavy metal (Cd, As, Pb, Zn, Cu, Cr, and Ni) control problem during the thermochemical recovery of phosphorus (P) from sewage sludge (SS), P-enriched sewage sludge ash (PSSA) was calcined at 1100°C. The effect of organic chlorinating agent (PVC) and inorganic chlorinating agent (MgCl2) on the fixed rate of P removal and the speciation transformation of heavy metal was studied. The removal of heavy metals Cd, Pb, As, Zn, and Cr exhibited an increasing tendency with the addition of chlorinating agent (PVC). However, an obvious peak under 100gCl/kg of PSSA appeared for Cu, owing to the presence of carbon and hydrogen in PVC. MgCl2 was found to be more effective than PVC in the removal of most heavy metals, such that up to 98.9% of Cu and 97.3% of Zn was effectively removed. Analyses of heavy metal forms showed that Pb and Zn occurred in the residue fraction after calcination. Meanwhile, the residue fraction of Cr, Ni, Cd, and Cu exhibited a decreasing tendency with the increase in the added chlorinating agent (MgCl2). Losses of P from PSSA were around 16.6% without the addition of chlorinating agent, which were greatly reduced to around 7.7% (PVC) and to only 1.7% (MgCl2). Copyright © 2014 Elsevier B.V. All rights reserved.

  17. Long-term calcination/carbonation cycling and thermal pretreatment for CO{sub 2} capture by limestone and dolomite

    Energy Technology Data Exchange (ETDEWEB)

    Zhongxiang Chen; Hoon Sub Song; Miguel Portillo; C. Jim Lim; John R. Grace; E.J. Anthony [University of British Columbia, Vancouver, BC (Canada). Department of Chemical and Biological Engineering

    2009-03-15

    Capturing carbon dioxide is vital for the future of climate-friendly combustion, gasification, and steam-re-forming processes. Dry processes utilizing simple sorbents have great potential in this regard. Long-term calcination/carbonation cycling was carried out in an atmospheric-pressure thermogravimetric reactor. Although dolomite gave better capture than limestone for a limited number of cycles, the advantage declined over many cycles. Under some circumstances, decreasing the carbonation temperature increased the rate of reaction because of the interaction between equilibrium and kinetic factors. Limestone and dolomite, after being pretreated thermally at high temperatures (1000 or 1100{sup o}C), showed a substantial increase in calcium utilization over many calcination/carbonation cycles. Lengthening the pretreatment interval resulted in greater improvement. However, attrition was significantly greater for the pretreated sorbents. Greatly extending the duration of carbonation during one cycle was found to be capable of restoring the CO{sub 2} capture ability of sorbents to their original behavior, offering a possible means of countering the long-term degradation of calcium sorbents for dry capture of carbon dioxide. 12 refs., 12 figs., 2 tabs.

  18. Carbothermic reduction of electric arc furnace dust and calcination of waelz oxide by semi-pilot scale rotary furnace

    Directory of Open Access Journals (Sweden)

    Morcali M.H.

    2012-01-01

    Full Text Available The paper gives a common outline about the known recycling techniques from electric arc furnace dusts and describes an investigation of a pyrometallurgical process for the recovery of zinc and iron from electric arc furnace dusts (EAFD. In the waelz process, the reduction of zinc and iron from the waste oxides using solid carbon (lignite coal was studied. In the reduction experiments; temperature, time and charge type (powder and pellet were investigated in detail. It was demonstrated that zinc and iron recovery (% increases with increasing temperature as well as time. Pelletizing was found to be a better method than using the powder as received for the zinc recovery and iron conversion (. In the calcination (roasting process, crude zinc oxide, which evaporated from non-ferric metals were collected as condensed product (crude waelz oxide, was heated in air atmosphere. Lead, cadmium as well as chlorine and other impurities were successfully removed from crude waelz oxide by this method. In the calcination experiments; temperature and time are investigated in detail. It was demonstrated that zinc purification (% increases with increasing temperature. The highest zinc refining (% was obtained at 1200°C for 120 minutes. A kinetic study was also undertaken to determine the activation energy of the process. Activation energies were 242.77 kJ/mol for the zinc recovery with powder forms, 261.99 kJ/mol for the zinc recovery with pellet forms respectively. It was found that, initially, the reaction was chemically controlled.

  19. Effects of Calcination Temperature and Acid-Base Properties on Mixed Potential Ammonia Sensors Modified by Metal Oxides

    Science.gov (United States)

    Satsuma, Atsushi; Katagiri, Makoto; Kakimoto, Shiro; Sugaya, Satoshi; Shimizu, Kenichi

    2011-01-01

    Mixed potential sensors were fabriated using yttria-stabilized zirconia (YSZ) as a solid electrolyte and a mixture of Au and various metal oxides as a sensing electrode. The effects of calcination temperature ranging from 600 to 1,000 °C and acid-base properties of the metal oxides on the sensing properties were examined. The selective sensing of ammonia was achieved by modification of the sensing electrode using MoO3, Bi2O3 and V2O5, while the use of WO3, Nb2O5 and MgO was not effective. The melting points of the former group were below 820 °C, while those of the latter group were higher than 1,000 °C. Among the former group, the selective sensing of ammonia was strongly dependent on the calcination temperature, which was optimum around melting point of the corresponding metal oxides. The good spreading of the metal oxides on the electrode is suggested to be one of the important factors. In the former group, the relative response of ammonia to propene was in the order of MoO3 > Bi2O3 > V2O5, which agreed well with the acidity of the metal oxides. The importance of the acidic properties of metal oxides for ammonia sensing was clarified. PMID:22319402

  20. Relevance of the Physicochemical Properties of Calcined Quail Eggshell (CaO as a Catalyst for Biodiesel Production

    Directory of Open Access Journals (Sweden)

    Leandro Marques Correia

    2017-01-01

    Full Text Available The CaO solid derived from natural quail eggshell was calcined and employed as catalyst to produce biodiesel via transesterification of sunflower oil. The natural quail eggshell was calcined at 900°C for 3 h, in order to modify the calcium carbonate present in its structure in CaO, the activity phase of the catalyst. Both precursor and catalyst were characterized using Hammett indicators method, X-ray fluorescence (XRF, X-ray diffraction (XRD, thermogravimetric analysis (TG/DTG, CO2 temperature-programmed desorption (CO2-TPD, X-ray photoelectronic spectroscopy (XPS, Fourier infrared spectroscopy (FTIR, scanning electron microscopy (SEM, N2 adsorption-desorption at −196°C, and distribution particle size. The maximum biodiesel production was of 99.00 ± 0.02 wt.% obtained in the following transesterification reaction conditions: XMR (sunflower oil/methanol molar ratio of 1 : 10.5 mol : mol, XCAT (catalyst loading of 2 wt.%, XTIME (reaction time of 2 h, stirring rate of 1000 rpm, and temperature of 60°C.

  1. Platelet aggregates and ADP-induced platelet aggregation in ...

    African Journals Online (AJOL)

    Hypertension is a condition characterized by haemodynamic vascular stress and abnormal blood flow under high pressure and it is associated with complications that are, paradoxically, thrombotic rather than haemorrhagic. Spontaneous platelet aggregation has been known to be present in hypertension which predicts ...

  2. Environmentalism and natural aggregate mining

    Science.gov (United States)

    Drew, L.J.; Langer, W.H.; Sachs, J.S.

    2002-01-01

    Sustaining a developed economy and expanding a developing one require the use of large volumes of natural aggregate. Almost all human activity (commercial, recreational, or leisure) is transacted in or on facilities constructed from natural aggregate. In our urban and suburban worlds, we are almost totally dependent on supplies of water collected behind dams and transported through aqueducts made from concrete. Natural aggregate is essential to the facilities that produce energy-hydroelectric dams and coal-fired powerplants. Ironically, the utility created for mankind by the use of natural aggregate is rarely compared favorably with the environmental impacts of mining it. Instead, the empty quarries and pits are seen as large negative environmental consequences. At the root of this disassociation is the philosophy of environmentalism, which flavors our perceptions of the excavation, processing, and distribution of natural aggregate. The two end-member ideas in this philosophy are ecocentrism and anthropocentrism. Ecocentrism takes the position that the natural world is a organism whose arteries are the rivers-their flow must not be altered. The soil is another vital organ and must not be covered with concrete and asphalt. The motto of the ecocentrist is "man must live more lightly on the land." The anthropocentrist wants clean water and air and an uncluttered landscape for human use. Mining is allowed and even encouraged, but dust and noise from quarry and pit operations must be minimized. The large volume of truck traffic is viewed as a real menace to human life and should be regulated and isolated. The environmental problems that the producers of natural aggregate (crushed stone and sand and gravel) face today are mostly difficult social and political concerns associated with the large holes dug in the ground and the large volume of heavy truck traffic associated with quarry and pit operations. These concerns have increased in recent years as society's demand for

  3. Balancing energy flexibilities through aggregation

    DEFF Research Database (Denmark)

    Valsomatzis, Emmanouil; Hose, Katja; Pedersen, Torben Bach

    2014-01-01

    in both energy production and consumption, is the key to solving these problems. Flexibilities can be expressed as flex-offers, which due to their high number need to be aggregated to reduce the complexity of energy scheduling. In this paper, we discuss balance aggregation techniques that already during......One of the main goals of recent developments in the Smart Grid area is to increase the use of renewable energy sources. These sources are characterized by energy fluctuations that might lead to energy imbalances and congestions in the electricity grid. Exploiting inherent flexibilities, which exist...

  4. Spring 2009 Semiannual (III.H. and I.U.) Report for the HWMA/RCRA Post-Closure Permit for the INTEC Waste Calcining Facility at the INL Site

    Energy Technology Data Exchange (ETDEWEB)

    Boehmer, Ann M.

    2009-05-31

    The Waste Calcining Facility is located at the Idaho Nuclear Technology and Engineering Center. In 1999, the Waste Calcining Facility was closed under and approved Hazardous Waste Management Act/Resource Conservation and Recovery Act Closure plan. Vessels and spaces were grouted and then covered with a concrete cap. This permit sets forth procedural requirements for groundwater characterization and monitoring, maintenance, and inspections of the Waste Calcining Facility to ensure continued protection of human health and the environment.

  5. Shape characterization of concrete aggregate

    NARCIS (Netherlands)

    Stroeven, P.; Hu, J.

    2006-01-01

    As a composite material, the performance of concrete materials can be expected to depend on the properties of the interfaces between its two major components, aggregate and cement paste. The microstructure at the interfacial transition zone (ITZ) is assumed to be different from the bulk material. In

  6. POLYAMINES IN MODULATING PROTEIN AGGREGATION

    Directory of Open Access Journals (Sweden)

    Rimpy K. Chowhan

    2012-12-01

    Full Text Available Polyamines are ubiquitous aliphatic polycations with multiple molecular and cellular functions. They were first indentified by Leeuwenhoek in 1678. Since then many investigations had been done to understand the physiological significance of these molecules. Being cationic at physiologic pH, they interact with various biomolecules including DNA, RNA, proteins, and help in many cellular functions. Apart from their vast number of physiological functions, they are also implicated in modulation of protein aggregation or amyloid formation. It is now important to combine and analyze all of the findings on polyamine-induced aggregation, come to a conclusion, and relate the phenomenon of this protein aggregation to the physiology of the cellular function. Through this review, we had tried to cover almost all the investigations that had been done to-date, to explore the roles of polyamines in aggregation of various proteins. We have also incorporated future research avenues that might be of interest to many cellular biologist and protein chemists.

  7. Diversity, intent, and aggregated search

    NARCIS (Netherlands)

    de Rijke, M.

    2014-01-01

    Diversity, intent and aggregated search are three core retrieval concepts that receive significant attention. In search result diversification one typically considers the relevance of a document in light of other retrieved documents. The goal is to identify the probable "aspects" of an ambiguous

  8. Aggregation Methods in Food Chains.

    NARCIS (Netherlands)

    Kooi, B.W.; Poggiale, J.C.; Auger, P.

    1998-01-01

    The aim of this paper is to apply aggregation methods to food chains under batch and chemostat conditions. These predator-prey systems are modelled using ODEs, one for each trophic level. Because the models are based on mass conservation laws, they are conservative and this allows perfect

  9. Excitons in tubular molecular aggregates

    NARCIS (Netherlands)

    Didraga, C; Knoester, J

    2004-01-01

    We present a brief overview of recent work on the optical properties of molecular aggregates with a tubular (cylindrical) shape. The exciton states responsible for these properties can be distinguished with regard to a transverse wave number, which directly relates to optical selection rules and

  10. Aggregating and Disaggregating Flexibility Objects

    DEFF Research Database (Denmark)

    Siksnys, Laurynas; Valsomatzis, Emmanouil; Hose, Katja

    2015-01-01

    of such objects while preserving flexibility. Hence, this paper formally defines the concept of flexibility objects (flex-objects) and provides a novel and efficient solution for aggregating and disaggregating flex-objects. Out of the broad range of possible applications, this paper will focus on smart grid...... the energy domain show that the proposed solutions provide good performance while satisfying the strict requirements....

  11. Studies on recycled aggregates-based concrete.

    Science.gov (United States)

    Rakshvir, Major; Barai, Sudhirkumar V

    2006-06-01

    Reduced extraction of raw materials, reduced transportation cost, improved profits, reduced environmental impact and fast-depleting reserves of conventional natural aggregates has necessitated the use of recycling, in order to be able to conserve conventional natural aggregate. In this study various physical and mechanical properties of recycled concrete aggregates were examined. Recycled concrete aggregates are different from natural aggregates and concrete made from them has specific properties. The percentages of recycled concrete aggregates were varied and it was observed that properties such as compressive strength showed a decrease of up to 10% as the percentage of recycled concrete aggregates increased. Water absorption of recycled aggregates was found to be greater than natural aggregates, and this needs to be compensated during mix design.

  12. Glass-ceramic waste forms for immobilization of the fluorinel-sodium, alumina, and zirconia calcines stored at the Idaho Chemical Processing Plant

    Energy Technology Data Exchange (ETDEWEB)

    Vinjamuri, K. [Idaho National Engineering Lab., Idaho Falls, ID (United States)

    1994-12-31

    Glass-ceramics appear to be very good candidate waste forms for immobilization of the calcined high level solid wastes, fluorinel-sodium (Fl/Na), alumina and zirconia that are stored at the Idaho Chemical Processing Plant (ICPP). Candidate experimental glass-ceramics were synthesized at ICPP by hot isostatically pressing (HIPing) a mixture of precompacted pilot plant calcine and additives. The glass-ceramic waste forms for immobilization of the Fl/Na, alumina, and zirconia calcines consist of 70 wt% Fl/Na calcine, 23.9 wt% SiO{sub 2}, 5 wt% Ti, 1.1 wt% B{sub 2}O{sub 3}; 70 wt% alumina calcine, 30 wt% SiO{sub 2}; and 70 wt% zirconia calcine, 20.25 wt% SiO{sub 2}, 5 wt% Ti, 2.25 wt% Na{sub 2}O, 1.75 wt% B{sub 2}O{sub 3}, 0.75 wt% Li{sub 2}O, respectively. The characteristics of the waste forms including density, chemical durability, glass and crystalline phases, and the microstructure are investigated. The 14-day MCC-1 total mass loss rates and the normalized elemental leach rates for aluminum, boron, calcium, cadmium, chromium, cesium, potassium, silicon, sodium, strontium, titanium, and zirconium are all less than 1 g/m{sup 2}-day. The crystalline phases for the Fl/Na and zirconia waste forms include zirconia, zircon, calcium fluoride, and titanates. In addition, cadmium sulphide in Fl/Na, and cadmium metal in zirconia waste form were also identified. The crystalline phases for the alumina waste form are alpha, gamma, and delta alumina, cristobalite, albite, and mullite. Glass phase separation was not observed in alumina and zirconia waste forms. The observed glass phase separation in Fl/Na waste form appears to be chemically durable.

  13. Calcination temperature effect on catalytic properties of Cr{sub 2} O{sub 3}/Al{sub 2} O{sub 3} aerogel: mild oxidation of toluene to benzaldehyde; Effet de la temperature de calcination sur les proprietes catalytiques de l`aerogel Cr{sub 2}O{sub 3}-AI{sub 2}O{sub 3}: oxydation menagee du toluene en benzaldehyde

    Energy Technology Data Exchange (ETDEWEB)

    Younes, M.K.; Ghorbel, A. [Faculte des Sciences de Tunis, (Tunisia); Naccache, C. [Centre National de la Recherche Scientifique (CNRS), 69 - Villeurbanne (France). Inst. de Recherches sur la Catalyse

    1997-11-01

    The aerogel catalyst Cr{sub 2}O{sub 3}-Al{sub 2}O{sub 3}(Cr/Al = 0,05) presents a high specific surface area and an amorphous structure. The beneficial role of alumina when it is added to chromia, is related to the stabilisation of both low coordinated Cr{sup 3+} and highly oxidized Cr{sup 5+} ions. A small change of the surface state is observed under heating treatment for temperature below 700 deg C. Above this temperature the surface structure changes. The Cr{sup 3+} ions are favoured and the majority of them remains on the catalyst surface as Cr{sub 2}O{sub 3} aggregates. The other part of chromium ions seems to be inserted in the alumina network. The effect of calcination is to decrease the catalytic activities of formation of all the products obtained in the toluene oxidation reaction and improves the benzaldehyde selectivity. (authors) 18 refs.

  14. Effect of different alcohols, gelatinizing times, calcination and microwave on characteristics of TiO2 nanoparticles synthesized by sol-gel method

    Science.gov (United States)

    Bahar, Mahmoud; Mozaffari, Masoud; Esmaeili, Sahar

    2017-03-01

    In this work, nanoparticles of titanium dioxide (TiO2) were synthesized by means of TiCl4 as precursor. Effects of alcohol type, calcination, gelatinizing time and microwave exposure on the particle size, morphology, crystallinity and particle phase are studied using XRD patterns and SEM images. Results showed that alcohols such as ethanol increased the particle size; calcination increased the particle size and improved the crystallinity of particles. Microwave exposure of particles resulted in smaller particles; adding water increased the impact of microwave. Effect of microwave exposure in rutile phase formation is also observed during this study.

  15. Effect of the preparation conditions on the catalytic activity of calcined Ca/Al-layered double hydroxides for the synthesis of glycerol carbonate

    OpenAIRE

    Salagre, P.; Granados-Reyes, J.; Cesteros, Y.

    2017-01-01

    Effect of the preparation conditions on the catalytic activity of calcined Ca/Al-layered double hydroxides for the synthesis of glycerol carbonate DOI: 10.1016/j.apcata.2017.02.013 URL: http://www.sciencedirect.com/science/article/pii/S0926860X17300686 Filiació URV: SI Memòria The effect of the preparation conditions of several calcined Ca/Al layered double hydroxide compounds (CaAl-LDH) on the catalytic transesterification of glycerol with dimethyl carbonate to obtain glycerol...

  16. Defining and Systematic Analyses of Aggregation Indices to Evaluate Degree of Calcium Oxalate Crystal Aggregation

    Directory of Open Access Journals (Sweden)

    Sakdithep Chaiyarit

    2017-12-01

    Full Text Available Crystal aggregation is one of the most crucial steps in kidney stone pathogenesis. However, previous studies of crystal aggregation were rarely done and quantitative analysis of aggregation degree was handicapped by a lack of the standard measurement. We thus performed an in vitro assay to generate aggregation of calcium oxalate monohydrate (COM crystals with various concentrations (25–800 μg/ml in saturated aggregation buffer. The crystal aggregates were analyzed by microscopic examination, UV-visible spectrophotometry, and GraphPad Prism6 software to define a total of 12 aggregation indices (including number of aggregates, aggregated mass index, optical density, aggregation coefficient, span, number of aggregates at plateau time-point, aggregated area index, aggregated diameter index, aggregated symmetry index, time constant, half-life, and rate constant. The data showed linear correlation between crystal concentration and almost all of these indices, except only for rate constant. Among these, number of aggregates provided the greatest regression coefficient (r = 0.997; p < 0.001, whereas the equally second rank included aggregated mass index and optical density (r = 0.993; p < 0.001 and r = −0.993; p < 0.001, respectively and the equally forth were aggregation coefficient and span (r = 0.991; p < 0.001 for both. These five indices are thus recommended as the most appropriate indices for quantitative analysis of COM crystal aggregation in vitro.

  17. Defining and Systematic Analyses of Aggregation Indices to Evaluate Degree of Calcium Oxalate Crystal Aggregation.

    Science.gov (United States)

    Chaiyarit, Sakdithep; Thongboonkerd, Visith

    2017-01-01

    Crystal aggregation is one of the most crucial steps in kidney stone pathogenesis. However, previous studies of crystal aggregation were rarely done and quantitative analysis of aggregation degree was handicapped by a lack of the standard measurement. We thus performed an in vitro assay to generate aggregation of calcium oxalate monohydrate (COM) crystals with various concentrations (25-800 μg/ml) in saturated aggregation buffer. The crystal aggregates were analyzed by microscopic examination, UV-visible spectrophotometry, and GraphPad Prism6 software to define a total of 12 aggregation indices (including number of aggregates, aggregated mass index, optical density, aggregation coefficient, span, number of aggregates at plateau time-point, aggregated area index, aggregated diameter index, aggregated symmetry index, time constant, half-life, and rate constant). The data showed linear correlation between crystal concentration and almost all of these indices, except only for rate constant. Among these, number of aggregates provided the greatest regression coefficient (r = 0.997; p < 0.001), whereas the equally second rank included aggregated mass index and optical density (r = 0.993; p < 0.001 and r = -0.993; p < 0.001, respectively) and the equally forth were aggregation coefficient and span (r = 0.991; p < 0.001 for both). These five indices are thus recommended as the most appropriate indices for quantitative analysis of COM crystal aggregation in vitro.

  18. Effects of surface features on sulfur dioxide adsorption on calcined NiAl hydrotalcite-like compounds.

    Science.gov (United States)

    Zhao, Ling; Li, Xinyong; Quan, Xie; Chen, Guohua

    2011-06-15

    The hydrotalcite-based NiAl mixed oxides were synthesized by coprecipitation and urea hydrolysis approaches and employed for SO₂ removal. The samples were well characterized by inductively coupled plasma (ICP) elemental analysis, X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and N₂ adsorption/desorption isotherm analyses. The acid-base properties were characterized by pyridine chemisorption and CO₂ temperature-programmed desorption (TPD). The calcined NiAlO from the urea method showed excellent SO₂ adsorption and its adsorption equilibrium showed a type I isotherm, which significantly improved the adsorption performance for low-concentration SO₂. Both the physical structure and the acidic-basic sites were found to play important roles in the SO₂ adsorption process. In situ Fourier transform infrared spectroscopy (FTIR) investigation revealed that adsorbed SO₂ molecules formed surface bisulfite, sulfite, and bidentate binuclear sulfate. The mechanisms for SO₂ adsorption and transformation are discussed in detail.

  19. Thermal and catalytic cracking of ethylene in presence of CaO, MgO, zeolite and calcined dolomite

    Energy Technology Data Exchange (ETDEWEB)

    Taralas, G.; Sjoestroem, K.; Jaeraas, S.; Bjoernbom, E. [Royal Inst. of Tech., Stockholm (Sweden). Dept. of Chemical Technology

    1993-12-31

    The subject of the present work is to study the effect of catalysts such as calcined dolomite (CaO.MgO), CaO (quicklime), MgO and Zeolite (EKZ-4) on the cracking of ethylene in the presence and absence of steam. N-heptane, toluene, naphthalene, thiophene have been some suitable model compounds for studies of the thermal and catalytic decomposition of tar. Previous results showed that the reaction scheme of the thermal decomposition of n-heptane was consistent with the high yield of ethylene observed in thermal decomposition of n-heptane. The effect of the reactor wall and the ferric impurities in the dolomite are also subjects of the research in this study. The results may also throw some additional light on the nature of the gas-phase thermal and catalytic reactions occurring in the use of dolomite as tar cracking catalysts. 28 refs

  20. Effectiveness factors for a commercial steam reforming (Ni) catalyst and for a calcined dolomite used downstream biomass gasifiers

    Energy Technology Data Exchange (ETDEWEB)

    Corella, J.; Narvaez, I.; Orio, A. [Madrid Univ. (Spain). Dept. of Chem. Eng.

    1996-12-31

    A commercial steam reforming catalyst from BASF, the G1-25 S one, and a calcined dolomite, Norte-1, from Cantabria-Spain, have been used, once crushed and sieved to different particle fractions between 1.0 and 4.0 mm. The materials have been tested downstream small pilot biomass gasifiers, bubbling fluidized bed type, gasifying with air and with steam. The Thiele modulus and the effectiveness factor have been calculated at temperatures of 750-850 deg C. It is experimentally shown that diffusion control plays an important part when particle size is larger than ca. 0.5 mm. This has to be taken into account when comparing the quality of the solids for tar elimination. (author) (5 refs.)

  1. Role of Multicellular Aggregates in Biofilm Formation

    National Research Council Canada - National Science Library

    Kragh, Kasper N; Hutchison, Jaime B; Melaugh, Gavin; Rodesney, Chris; Roberts, Aled E L; Irie, Yasuhiko; Jensen, Peter Ø; Diggle, Stephen P; Allen, Rosalind J; Gordon, Vernita; Bjarnsholt, Thomas

    2016-01-01

    .... However, in natural environments and during infection, bacterial cells tend to clump as multicellular aggregates, and biofilms can also slough off aggregates as a part of the dispersal process...

  2. Recycled concrete aggregate in portland cement concrete.

    Science.gov (United States)

    2013-01-01

    Aggregates can be produced by crushing hydraulic cement concrete and are known as recycled concrete : aggregates (RCA). This report provides results from a New Jersey Department of Transportation study to identify : barriers to the use of RCA in new ...

  3. Partially clairvoyant scheduling for aggregate constraints

    Directory of Open Access Journals (Sweden)

    K. Subramani

    2005-01-01

    constraints. In this paper, we extend the class of constraints for which partially clairvoyant schedules can be determined efficiently, to include aggregate constraints. Aggregate constraints form a strict superset of standard constraints and can be used to model performance metrics.

  4. Limestone calcined clay cement as a low-carbon solution to meet expanding cement demand in emerging economies

    Directory of Open Access Journals (Sweden)

    Yudiesky Cancio Díaz

    Full Text Available This paper aims at assessing the return on investment and carbon mitigation potentials of five investment alternatives for the Cuban cement industry in a long-term horizon appraisal (15 years. Anticipated growing demand for cement, constrained supply and an urgent need for optimisation of limited capital while preserving the environment, are background facts leading to the present study. This research explores the beneficial contribution of a new available technology, LC3 cement, resulting from the combination of clinker, calcined clay and limestone, with a capacity of replacing up to 50% of clinker in cement. Global Warming Potential (GWP is calculated with Life Cycle Assessment method and the economic investment's payback is assessed through Return on Capital Employed (ROCE approach. Main outcomes show that projected demand could be satisfied either by adding new cement plants—at a high environmental impact and unprofitable performance— or by introducing LC3 strategy. The latter choice allows boosting both the return on investment and the production capacity while reducing greenhouse gas (GHG emissions up to 20–23% compared to business-as-usual practice. Overall profitability for the industry is estimated to overcome BAU scenario by 8–10% points by 2025, if LC3 were adopted. Increasing the production of conventional blended cements instead brings only marginal economic benefits without supporting the needed increase in production capacity. The conducted study also shows that, in spite of the extra capital cost required for the calcination of kaolinite clay, LC3 drops production costs in the range of 15–25% compared to conventional solutions. Keywords: Cement, Alternative, ROCE, CO2, LCA, Investment

  5. Synthesis of zeolites Na-A and Na-X from tablet compressed and calcinated coal fly ash

    Science.gov (United States)

    Hu, Tao; Gao, Wenyan; Liu, Xin; Zhang, Yifu; Meng, Changgong

    2017-10-01

    Zeolites Na-A and Na-X are important synthetic zeolites widely used for separation and adsorption in industry. It is of great significance to develop energy-efficient routines that can synthesize zeolites Na-A and Na-X from low-cost raw materials. Coal fly ash (CFA) is the major residue from the combustion of coal and biomass containing more than 85% SiO2 and Al2O3, which can readily replace the conventionally used sodium silicate and aluminate for zeolite synthesis. We used Na2CO3 to replace the expensive NaOH used for the calcination of CFA and showed that tablet compression can enhance the contact with Na2CO3 for the activation of CFA through calcination for the synthesis of zeolites Na-A and Na-X under mild conditions. We optimized the control variables for zeolite synthesis and showed that phase-pure zeolite Na-A can be synthesized with CFA at reactant molar ratio, hydrothermal reaction temperature and reaction time of 1.3Na2O: 0.6Al2O3: 1SiO2: 38H2O at 80°C for 6 h, respectively, while phase-pure zeolite Na-X can be synthesized at 2.2Na2O: 0.2Al2O3: 1SiO2: 88H2O at 100°C for 8 h, respectively. The composition, morphology, specific surface area, vibration spectrum and thermogravimetry of synthesized Na-A and Na-X were further characterized.

  6. Recycled aggregate concrete; an overview

    OpenAIRE

    Sorato, Renan

    2016-01-01

    The aim of this Bachelor’s thesis was to investigate whether recycled materials can be incorporated into the production of concrete without compromising the compressive strength of the concrete produced. In order to shed light on the compressive strength of concrete made from recycled materials, the thesis reviewed studies in which waste materials are utilised as recycled aggregates in the composition of concrete and presented the results of this synthesis and analysis. It was found that som...

  7. Extremes of Aggregated Dirichlet Risks

    OpenAIRE

    Hashorva, Enkelejd

    2014-01-01

    The class of Dirichlet random vectors is central in numerous probabilistic and statistical applications. The main result of this paper derives the exact tail asymptotics of the aggregated risk of powers of Dirichlet random vectors when the radial component has df in the Gumbel or the Weibull max-domain of attraction. We present further results for the joint asymptotic independence and the max-sum equivalence.

  8. Intuitionistic fuzzy aggregation and clustering

    CERN Document Server

    Xu, Zeshui

    2012-01-01

    This book offers a systematic introduction to the clustering algorithms for intuitionistic fuzzy values, the latest research results in intuitionistic fuzzy aggregation techniques, the extended results in interval-valued intuitionistic fuzzy environments, and their applications in multi-attribute decision making, such as supply chain management, military system performance evaluation, project management, venture capital, information system selection, building materials classification, and operational plan assessment, etc.

  9. Aggregation and Control of Flexible Consumers

    DEFF Research Database (Denmark)

    Biegel, Benjamin; Andersen, Palle; Stoustrup, Jakob

    2014-01-01

    In this paper, we present an architecture for aggregation and co ntrol of a portfolio of flexible consumers. The architecture makes it possible to control the aggregated consumption of the portfolio to follow a power reference while honoring local consumer constraints. Hereby, an aggregator is able...

  10. Comparative analysis of aggregate agricultural productivity between ...

    African Journals Online (AJOL)

    GREGORY

    2010-08-23

    Aug 23, 2010 ... used animal manure had a higher aggregate agricultural productivity than the HEIT farmers who used inorganic fertilizer. ... utilization of animal manure be put in place by the government. Key words: Aggregate agricultural .... (Kelly et al., 1995). To compare input productivities across goods or to aggregate.

  11. Comparative evaluation of mineral trioxide aggregate and ...

    African Journals Online (AJOL)

    nanoparticles sized bioceramic BioAggregate (DiaRoot. BioAggregate, Innovative BioCeramix Inc., ... with cotton pellets and reinforced with zinc oxide eugenol cement (IRM, Dentsply International Inc., Milford, ..... Zhang H, Pappen FG, Haapasalo M. Dentin enhances the antibacterial effect of mineral trioxide aggregate and ...

  12. Locally available aggregate and sediment production

    Science.gov (United States)

    Randy B. Foltz; Mark Truebe

    2003-01-01

    Selection of suitable locally available materials to build strong and durable roads with aggregate surfaces is desired to minimize road construction and maintenance costs and to minimize the detrimental effects of sedimentation. Eighteen aggregates were selected from local sources in Idaho, Oregon, South Dakota, and Washington State. Aggregate was placed in shallow...

  13. Preparation of Calcined Zirconia-Carbon Composite from Metal Organic Frameworks and Its Application to Adsorption of Crystal Violet and Salicylic Acid

    Directory of Open Access Journals (Sweden)

    Zubair Hasan

    2016-03-01

    Full Text Available Zirconia-carbon (ZC composites were prepared via calcination of Zr-based metal organic frameworks, UiO-66 and amino-functionalized UiO-66, under N2 atmosphere. The prepared composites were characterized using a series of instrumental analyses. The surface area of the ZC composites increased with the increase of calcination temperature, with the formation of a graphite oxide phase observed at 900 °C. The composites were used for adsorptive removal of a dye (crystal violet, CV and a pharmaceutical and personal care product (salicylic acid, SA. The increase of the calcination temperature resulted in enhanced adsorption capability of the composites toward CV. The composite calcined at 900 °C exhibited a maximum uptake of 243 mg·g−1, which was much greater than that by a commercial activated carbon. The composite was also effective in SA adsorption (102 mg·g−1, and N-functionalization of the composite further enhanced its adsorption capability (109 mg·g−1. CV adsorption was weakly influenced by solution pH, but was more dependent on the surface area and pore volume of the ZC composite. Meanwhile, SA adsorption showed strong pH dependence, which implies an active role of electrostatic interactions in the adsorption process. Base-base repulsion and hydrogen bonding are also suggested to influence the adsorption of CV and SA, especially for the N-functionalized composite.

  14. Effect of Calcination Temperatures and Mo Modification on Nanocrystalline (γ-χ-Al2O3 Catalysts for Catalytic Ethanol Dehydration

    Directory of Open Access Journals (Sweden)

    Tharmmanoon Inmanee

    2017-01-01

    Full Text Available The mixed gamma and chi crystalline phase alumina (M-Al catalysts prepared by the solvothermal method were investigated for catalytic ethanol dehydration. The effects of calcination temperatures and Mo modification were elucidated. The catalysts were characterized by X-ray diffraction (XRD, N2 physisorption, transmission electron microscopy (TEM, and NH3-temperature programmed desorption (NH3-TPD. The catalytic activity was tested for ethylene production by dehydration reaction of ethanol in gas phase at atmospheric pressure and temperature between 200°C and 400°C. It was found that the calcination temperatures and Mo modification have effects on acidity of the catalysts. The increase in calcination temperature resulted in decreased acidity, while the Mo modification on the mixed phase alumina catalyst yielded increased acidity, especially in medium to strong acids. In this study, the catalytic activity of ethanol dehydration to ethylene apparently depends on the medium to strong acid. The mixed phase alumina catalyst calcined at 600°C (M-Al-600 exhibits the complete ethanol conversion having ethylene yield of 98.8% (at 350°C and the Mo-modified catalysts promoted dehydrogenation reaction to acetaldehyde. This can be attributed to the enhancement of medium to strong acid with metal sites of catalyst.

  15. Structural and paramagnetic behavior of spinel NiCr2O4 nanoparticles synthesized by thermal treatment method: Effect of calcination temperature

    Science.gov (United States)

    Bakar, Syuhada Abu; Soltani, Nayereh; Yunus, W. Mahmood Mat; Saion, Elias; Bahrami, Afarin

    2014-08-01

    Spinel nickel chromite nanoparticles were synthesized using a simple thermal treatment method. The effect of calcination temperatures on the final properties of obtained materials was carefully examined using various characterization techniques.The infrared spectra of nickel chromite (NiCr2O4) revealed the characteristic bonds of metal-oxygen for Nisbnd O and Crsbnd O bands around 600 and 470 cm-1, respectively. The powder X-ray diffraction patterns exhibited the formation of normal spinel phase of NiCr2O4 in the calcination process at temperature between 550 and 850 °C. From transmission electron micrographs, nanosized particles with average size of ~7-64 nm were observed at calcination temperatures of 550-850 °C, respectively. The calcined samples at 750 and 850 °C exhibited paramagnetic behavior with g-factor values of 1.92 and 2.15, peak-to-peak line width of 25.59 and 117.02 Oe and resonance magnetic field of 342.04 and 306.49 Oe, respectively. Variation in the value of g-factor, peak-to-peak line width and resonance magnetic field can be attributed to the dipole-dipole and super exchange interactions.

  16. Effects of calcination temperature for rate capability of triple-shelled ZnFe2O4 hollow microspheres for lithium ion battery anodes

    Science.gov (United States)

    Hwang, Hojin; Shin, Haeun; Lee, Wan-Jin

    2017-04-01

    Triple-shelled ZnFe2O4 hollow microspheres (ZFO) as anode materials for lithium ion battery are prepared through a one-pot hydrothermal reaction using the composite solution consisting of sucrose in water and metal ions in ethylene glycol (EG), followed by different calcination processes. The architectures of ZFO micro spheres are differently synthesized through a mutual cooperation of inward and outward ripening with three different calcination temperatures. Thin triple-shelled ZnFe2O4 hollow microspheres calcined at 450 °C (ZFO-450) delivers a high reversible capacity of 932 mA h g-1 at a current density of 2 A g-1 even at the 200th cycle without obvious decay. Furthermore, ZFO-450 delivers 1235, 1005, 865, 834, and 845 mA h g-1 at high current densities of 0.5, 2, 5, 10, and 20 A g-1 after 100 cycles. Thin triple-shelled hollow microsphere prepared at an optimum calcination temperature provides exceptional rate capability and outstanding rate retention due to (i) the formation of nanoparticles leading to thin shell with morphological integrity, (ii) the facile mass transfer by thin shell with mesoporous structure, and (iii) the void space with macroporous structure alleviating volume change occurring during cycling.

  17. Aqueous chemical route synthesis and the effect of calcination temperature on the structural and optical properties of ZnO nanoparticles

    Directory of Open Access Journals (Sweden)

    Mohammad Ramzan Parra

    2014-10-01

    Full Text Available This article reports the controlled size of ZnO nanoparticles synthesized via simple aqueous chemical route without the involvement of any capping agent. The effect of different calcination temperatures on the size of the ZnO nanoparticles was investigated. X-ray diffraction (XRD results indicated that all the samples have crystalline wurtzite phase, and peak broadening analysis was used to evaluate the average crystallite size and lattice strain using Scherrer's equation and Williamson–Hall (W–H method. Morphology and elemental compositions were investigated using atomic force microscopy (AFM and scanning electron microscopy (SEM with energy-dispersive X-ray (EDX spectroscopy. The average crystallite size of ZnO nanoparticles estimated from Scherrer's formula and W–H analysis was found to increase with the increase in calcination temperature. These results were in good agreement with AFM results. Optical properties were investigated using UV–vis spectroscopy in diffused reflectance (DR mode, with a sharp increase in reflectivity at 375 nm and the material has a strong reflective characteristic after 420 nm at 500 °C calcination temperature. Furthermore, photoluminescence spectroscopic results revealed intensive ultraviolet (UV emission with reduced defect concentrations and a slight shifting in band gap energies with increased calcination temperature from 200 °C to 500 °C. This study suggests that the as-prepared ZnO nanoparticles with bandgap tunability might be utilized as window layer in optoelectronic devices.

  18. Effect of doped SiO2 and calcinations temperature on phase transformation of TiO2 photocatalyst prepared by sol-gel method

    Directory of Open Access Journals (Sweden)

    Sutham Niyomwas

    2008-05-01

    Full Text Available The purpose of this research was to study the effect of calcinations temperature and SiO2 addition on phase transformation,crystallite size, and photocatalytic activity of SiO2/TiO2 thin films by using indigo carmine as an indicator. Thecomposite particles were prepared by sol-gel method via calcinations at a temperature range of 300-700oC for 2 h, and thecomposite thin films were prepared by means of spin coating. The microstructure and crystallite size of pure TiO2 and SiO2/TiO2 composite powders were characterized by using XRD, SEM and DTA. It was found that anatase structures wereformed at a calcinations temperature range of 300-600oC and mixed phases of anatase and rutile were observed at a temperatureof 700oC. Crystallite size of pure TiO2 tends to increase with an increase in calcinations temperature. Doped SiO2in the TiO2 has an effect on crystal phases and crystallite size of the composite powders and thin films, resulting in thechange of the photocatalytic activity of TiO2.

  19. Influence of calcination temperature on the morphology and energy storage properties of cobalt oxide nanostructures directly grown over carbon cloth substrates

    KAUST Repository

    Baby, Rakhi Raghavan

    2013-09-23

    Nanostructured and mesoporous cobalt oxide (Co3O4) nanowire in flower-like arrangements have been directly grown over flexible carbon cloth collectors using solvothermal synthesis for supercapacitor applications. Changes in the morphology and porosity of the nanowire assemblies have been induced by manipulating the calcination temperature (200–300 °C) of the one-dimensional (1-D) structures, resulting in significant impact on their surface area and pseudocapacitive properties. As the calcination temperature increases from 200 to 250 °C, the flower morphology gradually modifies to the point where the electrolyte could access almost all the nanowires over the entire sample volume, resulting in an increase in specific capacitance from 334 to 605 Fg−1, depending on the nanowire electrode morphology. The 300 °C calcination results in the breakdown of the mesoporous morphology and decreases the efficiency of electrolyte diffusion, resulting in a drop in pseudocapacitance after 300 °C. A peak energy density of 44 Wh kg−1 has been obtained at a power density of 20 kW kg−1 for the 250 °C calcined sample.

  20. [Lysophosphatidic acid and human erythrocyte aggregation].

    Science.gov (United States)

    Sheremet'ev, Iu A; Popovicheva, A N; Levin, G Ia

    2014-01-01

    The effects of lysophosphatidic acid on the morphology and aggregation of human erythrocytes has been studied. Morphology of erythrocytes and their aggregates were studied by light microscopy. It has been shown that lysophosphatidic acid changes the shape of red blood cells: diskocyte become echinocytes. Aggregation of red blood cells (rouleaux) was significantly reduced in autoplasma. At the same time there is a strong aggregation of echinocytes. This was accompanied by the formation of microvesicles. Adding normal plasma to echinocytes restores shape and aggregation of red blood cells consisting of "rouleaux". A possible mechanism of action of lysophosphatidic acid on erythrocytes is discussed.

  1. [AGGREGATION OF METABOLICALLY DEPLETED HUMAN ERYTHROCYTES].

    Science.gov (United States)

    Sheremet'ev, Yu A; Popovicheva, A N; Rogozin, M M; Levin, G Ya

    2016-01-01

    An aggregation of erythrocytes in autologous plasma after blood storage for 14 days at 4 °C was studied using photometry and light microscopy. The decrease of ATP content, the formation of echinocytes and spheroechinocytes, the decrease of rouleaux form of erythrocyte aggregation were observed during the storage. On the other hand the aggregates of echinocytes were formed in the stored blood. The addition of plasma from the fresh blood didn't restore the normal discocytic shape and aggregation of erythrocytes in the stored blood. The possible mechanisms of erythrocytes and echinocytes aggregation are discussed.

  2. Structural, optical and morphological properties of post-growth calcined TiO{sub 2} nanopowder for opto-electronic device application: Ex-situ studies

    Energy Technology Data Exchange (ETDEWEB)

    Sathyaseelan, B., E-mail: bsseelan03@gmail.com [Dept of Physics, University College of Engineering Arni (A Constituent College of Anna University Chennai) Arni 632326, Tamil Nadu (India); Manikandan, E., E-mail: maniphysics@gmail.com [Central Research Laboratory, Sree Balaji Medical College & Hospital, Bharath University, BIHER, Chrompet, Chennai 600044, Tamil Nadu (India); UNESCO UNISA Africa Chair in Nanosciences & Nanotechnology, College of Graduate Studies, University of South Africa, Muckleneuk Ridge, PO Box 392, Pretoria (South Africa); Lakshmanan, V. [Dept of Physics, A.C.T College of Engineering & Technology, Nelvoy 603107 Kancheepuram (Dt), Tamil Nadu (India); Baskaran, I. [Dept of Physics, Arignar Anna Government Arts College, Cheyyar 604407, Tamil Nadu (India); Sivakumar, K. [Dept of Physics, Anna University, Chennai 600025, Tamil Nadu (India); Ladchumananandasivam, Rasiah [Dept of Textile Engineering & Post Graduate Programme in Mechanical Engineering Centre of Technology, Federal University of Rio Grande do Norte, Natal (Brazil); Kennedy, J. [UNESCO UNISA Africa Chair in Nanosciences & Nanotechnology, College of Graduate Studies, University of South Africa, Muckleneuk Ridge, PO Box 392, Pretoria (South Africa); The MacDiarmid Institute for Advanced Materials and Nanotechnology, PO Box 600, Wellington (New Zealand); Maaza, M., E-mail: maaza@tlabs.ac.za [UNESCO UNISA Africa Chair in Nanosciences & Nanotechnology, College of Graduate Studies, University of South Africa, Muckleneuk Ridge, PO Box 392, Pretoria (South Africa)

    2016-06-25

    Nanocrystalline TiO{sub 2} powders have been selectively prepared by the simple combustion reaction method using urea as a fuel. The crystalline powder was obtained using a silica basin heated directly on a hot plate at 500 °C until self-ignition occurred. After combustion process, the calcined products were obtained by heating the as-prepared powders for 1 h in air atmosphere at various sintering temperatures [500–900 °C]. The obtained nanopowder materials were systematically characterized by X-day diffraction (XRD), micro-Raman, UV–visible absorption (UV–vis), and Fourier transform infrared (FT-IR) spectroscopics. Powder XRD pattern shows the good agreement rutile phase structured TiO{sub 2} and the sharp diffraction peaks indicates good for crystallinity. The size of a symmetry of the nanoparticles have been measured with aid of a scanning electron microscopy (SEM), high resolution transmission electron microscopy (HR-TEM), and Brunauer, Emmett and Teller (BET) surface studies. The crystallinity of the powders was found to increase with respect to calcination temperatures. The average specific surface area of the particle was probed using gas adsorption–desorption measurements. Raman spectroscopy experiment was performed to ascertain the nature of TiO{sub 2} powder quality. UV–vis absorption spectra results showed the changes in the absorption edges of TiO{sub 2} report to increasing the calcinations temperatures. - Highlights: • TiO{sub 2} Nanocrystalline powders were prepared by simple combustion reaction method. • Calcined TiO{sub 2} nanopowder obtained by heating for 1 hr in air atmosphere at 500–900 °C. • Systematic characterization employed by XRD, micro-Raman, Optical, SEM, HRTEM. • The size symmetry of nanoparticles measured by electron microscopes BET methods. • Calcinations raises the crystallinity size enhanced for future opto-electronic devices.

  3. Increased photocatalytic activity of NiO and ZnO in photodegradation of a model drug aqueous solution: Effect of coupling, supporting, particles size and calcination temperature

    Energy Technology Data Exchange (ETDEWEB)

    Derikvandi, Hadis [Department of Chemistry, Shahreza Branch, Islamic Azad University, P.O. Box 311-86145, Shahreza, Isfahan, Iran (Iran, Islamic Republic of); Young Researchers and Elite Club, Shahreza Branch, Islamic Azad University, Shahreza (Iran, Islamic Republic of); Nezamzadeh-Ejhieh, Alireza, E-mail: arnezamzadeh@iaush.ac.ir [Department of Chemistry, Shahreza Branch, Islamic Azad University, P.O. Box 311-86145, Shahreza, Isfahan, Iran (Iran, Islamic Republic of); Young Researchers and Elite Club, Shahreza Branch, Islamic Azad University, Shahreza (Iran, Islamic Republic of); Razi Chemistry Research Center (RCRC), Shahreza Branch, Islamic Azad University, Isfahan (Iran, Islamic Republic of)

    2017-01-05

    Highlights: • Increased photoactivity of hybridized/supported NiO-ZnO whit respect to monocomponent one. • Strong dependence of photocatalytic activity of NiO-ZnO to calcination temperature. • Calcination temperature varied the crystallite forms of the semiconductors. • Red shifts in band gaps of the supported coupled semiconductors whit respect to monocomponent one. - Abstract: Mechanically ball-mill prepared clinoptilolite nanoparticles (NC) were used for increasing photocatalytic activity of NiO and ZnO as alone and binary systems. The semiconductors were supported onto the zeolite during calcination of Ni(II)-Zn(II)-exchanged NC at different calcinations temperatures. XRD, FTIR, SEM-EDX, X-ray mapping, DRS, TEM and BET techniques were used for characterization of the samples. The calcined catalysts at 400 °C for 4 h showed the best photocatalytic activity for metronidazole (MNZ) in aqueous solution. The mole ratio of ZnO/NiO affected the photodegradation efficiency because activity of the coupled catalysts depends to the both e/h production and electron scavenging processes. In the used system, NiO acted as e/h production source and ZnO as an electron sink. Red shifts in band gaps of the supported coupled semiconductors was observed whit respect to monocomponent one, confirming formation of nanoparticles of the semiconductors onto the zeolitic bed. The best activities were obtained for the NiO{sub 1.3}–ZnO{sub 1.5}/NC (NZ-NC) and NiO{sub 0.7}–ZnO{sub 4.3}/NC (NZ{sub 3}-NC) catalysts at pH 3, 1.2 g L{sup −1} of the catalysts and 1 g L{sup −1} of MNZ.

  4. Does thermophoresis reduce aggregate stability?

    Science.gov (United States)

    Sachs, Eyal; Sarah, Pariente

    2017-04-01

    Thermophoresis is mass flow driven by a thermal gradient. As a result of Seebeck effect and Soret effect, colloids can move from the hot to the cold region or vice versa, depending on the electrolyte composition and on the particle size. This migration of colloids can weaken aggregates. The effect of raindrop temperatures on runoff generation and erosion on clayey soil was investigated in sprinkling experiments with a laboratory rotating disk rain simulator. The experiments were applied to Rhodoxeralt (Terra Rossa) soil with two pre-prepared moisture contents: hygroscopic and field capacity. For each moisture content three rainfall temperatures were applied: 2, 20, and 35°C. Erosion was generally lower in the pre-wetted soil than in the dry soil (12.5 and 24.4 g m-2 per 40 mm of rain,respectively). Whereas there was no significant effect of raindrop temperature on the dry soil the soil that was pre-moistened to field capacity was affected by rainwater temperature: runoff and erosion were high when the temperature difference between rainfall and soil surface was high, sediment yields were 13.9, 5.2, and 18.3 g m-2 per 40 mm of rain, for rain temperature of 2, 20, and 35 °C, respectively. It is reasonable to conclude that thermophoresis caused by thermal gradients within the soil solution reduces the stability of aggregates and then increase the soil losses.

  5. LAB-SCALE DEMONSTRATION OF PLUTONIUM PURIFICATION BY ANION EXCHANGE, PLUTONIUM (IV) OXALATE PRECIPITATION, AND CALCINATION TO PLUTONIUM OXIDE TO SUPPORT THE MOX FEED MISSION

    Energy Technology Data Exchange (ETDEWEB)

    Crowder, M.; Pierce, R.

    2012-08-22

    H-Canyon and HB-Line are tasked with the production of PuO{sub 2} from a feed of plutonium metal. The PuO{sub 2} will provide feed material for the MOX Fuel Fabrication Facility. After dissolution of the Pu metal in H-Canyon, the solution will be transferred to HB-Line for purification by anion exchange. Subsequent unit operations include Pu(IV) oxalate precipitation, filtration and calcination to form PuO{sub 2}. This report details the results from SRNL anion exchange, precipitation, filtration, calcination, and characterization tests, as requested by HB-Line1 and described in the task plan. This study involved an 80-g batch of Pu and employed test conditions prototypical of HB-Line conditions, wherever feasible. In addition, this study integrated lessons learned from earlier anion exchange and precipitation and calcination studies. H-Area Engineering selected direct strike Pu(IV) oxalate precipitation to produce a more dense PuO{sub 2} product than expected from Pu(III) oxalate precipitation. One benefit of the Pu(IV) approach is that it eliminates the need for reduction by ascorbic acid. The proposed HB-Line precipitation process involves a digestion time of 5 minutes after the time (44 min) required for oxalic acid addition. These were the conditions during HB-line production of neptunium oxide (NpO{sub 2}). In addition, a series of small Pu(IV) oxalate precipitation tests with different digestion times were conducted to better understand the effect of digestion time on particle size, filtration efficiency and other factors. To test the recommended process conditions, researchers performed two nearly-identical larger-scale precipitation and calcination tests. The calcined batches of PuO{sub 2} were characterized for density, specific surface area (SSA), particle size, moisture content, and impurities. Because the 3013 Standard requires that the calcination (or stabilization) process eliminate organics, characterization of PuO{sub 2} batches monitored the

  6. Aggregation and fibrillation of bovine serum albumin

    DEFF Research Database (Denmark)

    Holm, NK; Jespersen, SK; Thomassen, LV

    2007-01-01

    The all-alpha helix multi-domain protein bovine serum albumin (BSA) aggregates at elevated temperatures. Here we show that these thermal aggregates have amyloid properties. They bind the fibril-specific dyes Thioflavin T and Congo Red, show elongated although somewhat worm-like morphology...... and characteristic amyloid X-ray fiber diffraction peaks. Fibrillation occurs over minutes to hours without a lag phase, is independent of seeding and shows only moderate concentration dependence, suggesting intramolecular aggregation nuclei. Nevertheless, multi-exponential increases in dye-binding signal...... and changes in morphology suggest the existence of different aggregate species. Although beta-sheet content increases from 0 to ca. 40% upon aggregation, the aggregates retain significant amounts of alpha-helix structure, and lack a protease-resistant core. Thus BSA is able to form well-ordered beta...

  7. A dimension map for molecular aggregates.

    Science.gov (United States)

    Jian, Cuiying; Tang, Tian; Bhattacharjee, Subir

    2015-05-01

    A pair of gyradius ratios, defined from the principal radii of gyration, are used to generate a dimension map that describes the geometry of molecular aggregates in water and in organic solvents. Molecular dynamics simulations were performed on the aggregation of representative biomolecules and polyaromatic compounds to demonstrate application of the dimension map. It was shown that molecular aggregate data on the dimension map were bounded by two boundary curves, and that the map could be separated into three regions representing three groups of structures: one-dimensional rod-like structures; two-dimensional planar structures or short-cylinder-like structures; and three-dimensional sphere-like structures. Examining the location of the aggregates on the dimension map and how the location changes with solvent type and solute material parameter provides a simple yet effective way to infer the aggregation manner and to study solubility and mechanism of aggregation. Copyright © 2015 Elsevier Inc. All rights reserved.

  8. Role of multicellular aggregates in biofilm formation

    DEFF Research Database (Denmark)

    Kragh, Kasper N.; Hutchison, Jaime B.; Melaugh, Gavin

    2016-01-01

    In traditional models of in vitro biofilm development, individual bacterial cells seed a surface, multiply, and mature into multicellular, three-dimensional structures. Much research has been devoted to elucidating the mechanisms governing the initial attachment of single cells to surfaces. However......, in natural environments and during infection, bacterial cells tend to clump as multicellular aggregates, and biofilms can also slough off aggregates as a part of the dispersal process. This makes it likely that biofilms are often seeded by aggregates and single cells, yet how these aggregates impact biofilm...... initiation and development is not known. Here we use a combination of experimental and computational approaches to determine the relative fitness of single cells and preformed aggregates during early development of Pseudomonas aeruginosa biofilms. We find that the relative fitness of aggregates depends...

  9. Aggregation server for grid-integrated vehicles

    Science.gov (United States)

    Kempton, Willett

    2015-05-26

    Methods, systems, and apparatus for aggregating electric power flow between an electric grid and electric vehicles are disclosed. An apparatus for aggregating power flow may include a memory and a processor coupled to the memory to receive electric vehicle equipment (EVE) attributes from a plurality of EVEs, aggregate EVE attributes, predict total available capacity based on the EVE attributes, and dispatch at least a portion of the total available capacity to the grid. Power flow may be aggregated by receiving EVE operational parameters from each EVE, aggregating the received EVE operational parameters, predicting total available capacity based on the aggregated EVE operational parameters, and dispatching at least a portion of the total available capacity to the grid.

  10. Internal water curing with Liapor aggregates

    DEFF Research Database (Denmark)

    Lura, Pietro

    2005-01-01

    Internal water curing is a very efficient way to counteract self-desiccation and autogenous shrinkage in high performance concrete, thereby reducing the likelihood of early-age cracking. This paper deals with early-age volume changes and moisture transport in lightweight aggregate concrete realized...... with wet lightweight aggregates. Lightweight aggregate concrete mixtures with different degree of saturation and different particle size of the lightweight aggregates were studied and compared to normal weight concrete. Autogenous deformations, selfinduced stresses in fully restrained conditions, elastic...... modulus and compressive strength were measured. Early-age expansion of the mixtures was greater the higher the degree of the saturation of the lightweight aggregates and the finer their particle size. The elastic properties and the earlyage expansion of the lightweight aggregate concrete were calculated...

  11. Kinetics and Mechanism of NaOH-Impregnated Calcined Oyster Shell-Catalyzed Transesterification of Soybean Oil

    Directory of Open Access Journals (Sweden)

    Han Jin

    2017-11-01

    Full Text Available The objective of this research is to develop a kinetic model to describe the transesterification of soybean oil with methanol using NaOH-impregnated calcined oyster shell (Na-COS. Batch experiments were performed via a two-factor randomized complete block design using a molar ratio of methanol to oil (MR of 6, 12, and 18 and catalyst loadings (CL (mass of catalyst/mass of oil in % of 2%, 4%, 6%, and 8% to obtain fatty acid methyl ester yields. In addition, the catalyst was studied by X-ray diffraction (XRD, X-ray photoelectron spectroscopy (XPS, and time-of-flight secondary ion spectrometry (TOF-SIMS to elucidate the role of the catalyst in the transesterification reaction. XRD and XPS analyses suggested that the formation of sodium peroxide (Na2O2 on the surface contributed to catalytic activity. The TOF-SIMS analysis suggested that the transesterification occurred between adsorbed triglyceride and free methanol, similar to the Eley-Rideal mechanism. The transesterification of adsorbed triglyceride to adsorbed diglyceride was found to be the rate-determining step with a rate constant of 0.0059 ± 0.0002 L mol−1 min−1.

  12. Palm oil biodiesel synthesized with potassium loaded calcined hydrotalcite and effect of biodiesel blend on elastomer properties

    Energy Technology Data Exchange (ETDEWEB)

    Trakarnpruk, Wimonrat; Porntangjitlikit, Suriya [Petrochemistry and Polymer Science, Department of Chemistry, Faculty of Science, Chulalongkorn University, Bangkok 10330 (Thailand)

    2008-07-15

    Biodiesel was prepared from palm oil by transesterification with methanol in the presence of 1.5%K loaded-calcined Mg-Al hydrotalcite. Fatty acid methyl esters content of 96.9% and methyl ester yield of 86.6% were achieved using a 30:1 methanol to oil molar ratio at 100{sup o}C for 6 h and 7 wt% catalyst. The biodiesel was characterized and its impact on elastomer properties was evaluated. The compatibility of B10 diesel blend (10% biodiesel) with six types of elastomers commonly found in fuel systems (NBR, HNBR, NBR/PVC, acrylic rubber, co-polymer FKM, and terpolymer FKM) were investigated. The physical properties of elastomers after immersion in tested fuels (for 22, 670, and 1008 h at 100{sup o}C) were measured according to American Society of Testing and Materials (ASTM). These include swelling (mass change and volume change), hardness, tensile and elongation, as well as the dynamic mechanical property. The results showed that properties of NBR, NBR/PVC and acrylic rubber were affected more than other elastomers. This is due to the absorption and dissolving of biodiesel by rubber in these samples. Co-polymer FKM and terpolymer FKM which are fluoroelastomers show little property change. (author)

  13. Influences of the calcination temperature and polymethyl methacrylate templates to characteristic pore membrane of bioceramic titanium dioxide

    Science.gov (United States)

    Ady, Jan; Viandari, Eka; Hasanah, Dewi W.

    2017-05-01

    The synthesis of the bioceramics titanium dioxide on its template by polymethyl methacrylate to be a sample with forming TiO2/PMMA was made with sol-gel process, and its pore membrane characteristics has also been studied. Different calcination temperatures 500°C, 550°C, and 600°C were given to sample for 17 hours. This purpose themselves was to fill TiO2 fissures with PMMA on different concentrations of 0.0, 2.0 wt%, 3.0 wt%, 4.0 wt%. Template leaching technique was used to remove PMMA from samples, and it was then sequentially found of the pore size of the membrane in approximate ranges (1900 nm - 2000 nm), (860.5 nm - 1669 nm), (312.8 nm-382.5 nm), and (136.1 nm - 269.7 nm). SEM test using and fourth it has average thickness in about 6.7 nm with Ellipsometer measurement. The percentage values of titanium and oxygen atoms are found by SEM-EDX from 3.03 at.% up to 66.81 at.% and there is amount 99.99% of the sample in anatase phase forming at 550 0C with angle of diffraction is 25.410 and it was prepared by XRD measurement.

  14. Evolution of porous structure and texture in nanoporous SiO2/Al2O3 materials during calcination

    Science.gov (United States)

    Glazkova, Elena A.; Bakina, Olga V.

    2016-11-01

    The study focuses on the evolution of porous structure and texture of silica/alumina xerogels during calcination in the temperature range from 500 to 1200°C. The xerogel was prepared via sol-gel method using subcritical drying. The silica/alumina xerogels were examined using transmission electron microscopy-energy dispersive spectroscopy (TEM-EDS), Brunauer Emmett Teller-Barrett Joyner Halenda (BET-BJH), differential scanning calorimetry (DSC), and Fourier transform infrared (FTIR) spectroscopy. SiO2 primary particles of size about 10 nm are connected with each other to form a porous xerogel structure. Alumina is uniformly distributed over the xerogel volume. The changes of textural characteristics under heat treatment of samples are radical; the specific surface area and pore size attain their maximum at 500-700°C. The heat treatment of samples causes dehydroxylation of the xerogel surface, and at 1200°C the sample is sintered, loses mesoporosity, and its specific surface area reduces considerably down to 78 m2/g.

  15. Feasibility analysis of As(III) removal in a continuous flow fixed bed system by modified calcined bauxite (MCB).

    Science.gov (United States)

    Bhakat, P B; Gupta, A K; Ayoob, S

    2007-01-10

    This study examine the feasibility of As(III) removal from aqueous environment by an adsorbent, modified calcined bauxite (MCB) in a continuous flow fixed bed system. MCB exhibited excellent adsorption capacity of 520.2 mg/L (0.39 mg/g) with an adsorption rate constant 0.7658 L/mgh for an influent As(III) concentration of 1mg/L. In a 2 cm diameter continuous flow fixed MCB bed, a depth of only 1.765 cm was found necessary to produce effluent As(III) concentration of 0.01 mg/L, from an influent of 1 mg/L at a flow rate of 8 mL/min. Also, bed heights of 10, 20, and 30 cm could treat 427.85, 473.88 and 489.17 bed volumes of water, respectively, to breakthrough. A reduction in adsorption capacity of MCB was observed with increase in flow rates. The theoretical service times evaluated from bed depth service time (BDST) approach for different flow rates and influent As(III) concentrations had shown good correlation with the corresponding experimental values. The theoretical breakthrough curve developed from constantly mixed batch reactor (CMBR) isotherm data also correlated well with experimental breakthrough curve.

  16. In Situ IR Characterization of CO Interacting with Rh Nanoparticles Obtained by Calcination and Reduction of Hydrotalcite-Type Precursors

    Directory of Open Access Journals (Sweden)

    F. Basile

    2011-01-01

    Full Text Available Supported Rh nanoparticles obtained by reduction in hydrogen of severely calcined Rh/Mg/Al hydrotalcite-type (HT phases have been characterized by FT-IR spectroscopy of adsorbed CO [both at room temperature (r.t. and nominal liquid nitrogen temperature] and Transmission Electron Microscopy (TEM. The effect of reducing temperature has been investigated, showing that Rh crystal size increases from 1.4 nm to 1.8 nm when the reduction temperature increases from 750°C to 950°C. The crystal growth favours the formation of bridged CO species and linear monocarbonyl species with respect to gem-dicarbonyl species; when CO adsorbs at r.t., CO disproportionation occurs on Rh and it accompanies the formation of RhI(CO2. The role of interlayer anions in the HT precursors to affect the properties of the final materials has been also investigated considering samples prepared from silicate-instead of carbonate-containing precursors. In this case, formation of RhI(CO2 and CO disproportionation do not occur, and this evidence is discussed in terms of support effect.

  17. Competitive adsorption characteristics of fluoride and phosphate on calcined Mg-Al-CO3 layered double hydroxides.

    Science.gov (United States)

    Cai, Peng; Zheng, Hong; Wang, Chong; Ma, Hongwen; Hu, Jianchao; Pu, Yubing; Liang, Peng

    2012-04-30

    With synthetic wastewater, competitive adsorption characteristics of fluoride and phosphate on calcined Mg-Al-CO(3) layered double hydroxides (CLDH) were investigated. A series of batch experiments were performed to study the influence of various experimental parameters, such as pH, contact time, and order of addition of the anions on the competitive adsorption of fluoride and phosphate on CLDH. It was found that the optimal pH is around 6 and it took 24 h to attain equilibrium when fluoride and phosphate were simultaneous added. The order of addition of anions influenced the adsorption of fluoride and phosphate on CLDH. The kinetic data were analyzed using the pseudo first-order and pseudo second-order models and they were found to fit very well the pseudo second-order kinetic model. Data of equilibrium experiments were fitted well to Langmuir isotherm and the competitive monolayer adsorption capacities of fluoride and phosphate were found to be obviously lower than those of single anion at 25 °C. The results of X-ray diffraction, Scanning Electron Microscopy with energy-dispersive X-ray analyses, and ATR-FTIR demonstrate that the adsorption mechanism involves the rehydration of mixed metal oxides and concomitant intercalation of fluoride and phosphate ions into the interlayer to reconstruct the initial LDHs structure. Copyright © 2012 Elsevier B.V. All rights reserved.

  18. Familial Aggregation of Hyperemesis Gravidarum

    Science.gov (United States)

    Zhang, Yafeng; Cantor, Rita M.; Macgibbon, Kimber; Romero, Roberto; Goodwin, Thomas M.; Mullin, Patrick; Fejzo, Marlena S.

    2010-01-01

    Objective This study was undertaken to determine whether there is familial aggregation of Hyperemesis Gravidarum making it a disease amenable to genetic study. Study Design Cases with severe nausea and vomiting in a singleton pregnancy treated with intravenous hydration and unaffected friend controls completed a survey regarding family history. Results Sisters of women with Hyperemesis Gravidarum have a significantly increased risk of having Hyperemesis Gravidarum themselves (OR=17.3, p=0.005). Cases have a significantly increased risk of having a mother with severe nausea and vomiting; 33% of cases reported an affected mother compared to 7.7% of controls (pHyperemesis Gravidarum. This study provides strong evidence for a genetic component to hyperemesis gravidarum. Identification of the predisposing gene(s) may determine the cause of this poorly understood disease of pregnancy. PMID:20974461

  19. Macroeconomic susceptibility, inflation, and aggregate supply

    Science.gov (United States)

    Hawkins, Raymond J.

    2017-03-01

    We unify aggregate-supply dynamics as a time-dependent susceptibility-mediated relationship between inflation and aggregate economic output. In addition to representing well various observations of inflation-output dynamics this parsimonious formalism provides a straightforward derivation of popular representations of aggregate-supply dynamics and a natural basis for economic-agent expectations as an element of inflation formation. Our formalism also illuminates questions of causality and time-correlation that challenge central banks for whom aggregate-supply dynamics is a key constraint in their goal of achieving macroeconomic stability.

  20. Hierarchical organization in aggregates of protein molecules

    DEFF Research Database (Denmark)

    Bohr, Henrik; Kyhle, Anders; Sørensen, Alexis Hammer

    1997-01-01

    The aggregation of proteins into small clusters is studied by atomic force and electron microscopy. Scaling laws and fractal behaviour in the growth of the aggregates and in the correlation between aggregates is seen. A phase diagram of the aggregation process where the protonic concentration...... of the solution and the density of protein are varied shows the existence of specific growth processes resulting in different branch-like structures. The resulting structures are strongly influenced by the shape of each protein molecule. Lysozyme and ribonuclease are found to form spherical structures...

  1. Pre-aggregation for Probability Distributions

    DEFF Research Database (Denmark)

    Timko, Igor; Dyreson, Curtis E.; Pedersen, Torben Bach

    Motivated by the increasing need to analyze complex uncertain multidimensional data (e.g., in order to optimize and personalize location-based services), this paper proposes novel types of {\\em probabilistic} OLAP queries that operate on aggregate values that are probability distributions...... and the techniques to process these queries. The paper also presents the methods for computing the probability distributions, which enables pre-aggregation, and for using the pre-aggregated distributions for further aggregation. In order to achieve good time and space efficiency, the methods perform approximate...... multidimensional data analysis that is considered in this paper (i.e., approximate processing of probabilistic OLAP queries over probability distributions)....

  2. Immunogenicity of therapeutic proteins: influence of aggregation.

    Science.gov (United States)

    Ratanji, Kirsty D; Derrick, Jeremy P; Dearman, Rebecca J; Kimber, Ian

    2014-01-01

    The elicitation of anti-drug antibodies (ADA) against biotherapeutics can have detrimental effects on drug safety, efficacy, and pharmacokinetics. The immunogenicity of biotherapeutics is, therefore, an important issue. There is evidence that protein aggregation can result in enhanced immunogenicity; however, the precise immunological and biochemical mechanisms responsible are poorly defined. In the context of biotherapeutic drug development and safety assessment, understanding the mechanisms underlying aggregate immunogenicity is of considerable interest. This review provides an overview of the phenomenon of protein aggregation, the production of unwanted aggregates during bioprocessing, and how the immune response to aggregated protein differs from that provoked by non-aggregated protein. Of particular interest is the nature of the interaction of aggregates with the immune system and how subsequent ADA responses are induced. Pathways considered here include 'classical' activation of the immune system involving antigen presenting cells and, alternatively, the breakdown of B-cell tolerance. Additionally, methods available to screen for aggregation and immunogenicity will be described. With an increased understanding of aggregation-enhanced immune responses, it may be possible to develop improved manufacturing and screening processes to avoid, or at least reduce, the problems associated with ADA.

  3. Microbial aggregates in anaerobic wastewater treatment.

    Science.gov (United States)

    Kosaric, N; Blaszczyk, R

    1990-01-01

    The phenomenon aggregation of anaerobic bacteria gives an opportunity to speed up the digestion rate during methanogenesis. The aggregates are mainly composed of methanogenic bacteria which convert acetate and H2/CO2 into methane. Other bacteria are also included in the aggregates but their concentration is rather small. The aggregates may also be formed during acetogenesis or even hydrolysis but such aggregates are not stable and disrupt quickly when not fed. A two stage process seems to be suitable when high concentrated solid waste must be treated. Special conditions are necessary to promote aggregate formation from methanogenic bacteria but aggregates once formed are stable without feeding even for a few years. The structure, texture and activity of bacterial aggregates depend on several parameters: (1)--temperature and pH, (2)--wastewater composition and (3)--hydrodynamic conditions within the reactor. The common influence of all these parameters is still rather unknown but some recommendations may be given. Temperature and pH should be maintained in the range which is optimal for methanogenic bacteria e.g. a temperature between 32 and 50 degrees C and a value pH between 6.5 and 7.5. Wastewaters should contain soluble wastes and the specific loading rate should be around one kgCOD(kgVSS)-1 d-1. The concentration of the elements influences aggregate composition and probably structure and texture. At high calcium concentration a change in the colour of the granules has been observed. Research is necessary to investigate the influence of other elements and organic toxicants on maintenance of the aggregates. Hydrodynamic conditions seem to influence the stability of the granules over long time periods. At low liquid stream rates, aggregates may starve and lysis within the aggregates is possible which results in hollowing of aggregates and their floating. At high liquid stream rates the aggregates may be disrupted and washed out of the reactor as a flocculent

  4. Aggregated Dynamic Dataflow Graph Generation and Visualization

    Directory of Open Access Journals (Sweden)

    I. Szabó

    2013-12-01

    Full Text Available Aggregated Dynamic Dataflow Graphs can assist programmers to uncover the main data paths of a given algorithm. This information can be useful when scaling a singlethreaded program into a multi-core architecture. The amount of data movements is crucial when targeting for cache incoherent and/or heterogeneous platforms. This paper presents two methods for generating function-level Aggregated Dynamic Dataflow Graphs. Instruction level trace log was used as a basis, which was generated by Microsoft Giano processor simulator platform. Top-down aggregation strategy and relational database was used to speed up the generation of different views of the aggregated dataflow and call graphs.

  5. Familial aggregation and heritability of pyloric stenosis

    DEFF Research Database (Denmark)

    Krogh, Camilla; Fischer, Thea K; Skotte, Line

    2010-01-01

    for the first year of life, during which 3362 children had surgery for pyloric stenosis. MAIN OUTCOME MEASURE: Familial aggregation of pyloric stenosis, evaluated by rate ratios. RESULTS: The incidence rate (per 1000 person-years) of pyloric stenosis in the first year of life was 1.8 for singletons and 3......CONTEXT: Pyloric stenosis is the most common condition requiring surgery in the first months of life. Case reports have suggested familial aggregation, but to what extent this is caused by common environment or inheritance is unknown. OBJECTIVES: To investigate familial aggregation of pyloric...... familial aggregation and heritability....

  6. Effects of Calcination Temperatures on Photocatalytic Activity of Ordered Titanate Nanoribbon/SnO2 Films Fabricated during an EPD Process

    Directory of Open Access Journals (Sweden)

    Li Zhao

    2012-01-01

    Full Text Available Ordered titanate nanoribbon (TNR/SnO2 films were fabricated by electrophoretic deposition (EPD process using hydrothermally prepared titanate nanoribbon as a precursor. The formation mechanism of ordered TNR film on the fluorine-doped SnO2 coated (FTO glass was investigated by scanning electron microscopy (SEM. The effects of calcination temperatures on the phase structure and photocatalytic activity of ordered TNR/SnO2 films were investigated and discussed. The X-ray diffraction (XRD results indicate that the phase transformation of titanate to anatase occurs at 400°C and with increasing calcination temperature, the crystallization of anatase increases. At 600°C, the nanoribbon morphology still hold and the TiO2/SnO2 film exhibits the highest photocatalytic activity due to the good crystallization, unique morphology, and efficient photogenerated charge carriers separation and transfer at the interface of TiO2 and SnO2.

  7. Steam reforming of tar derived from lignin over pompom-like potassium-promoted iron-based catalysts formed on calcined scallop shell.

    Science.gov (United States)

    Guan, Guoqing; Kaewpanha, Malinee; Hao, Xiaogang; Zhu, Ai-Min; Kasai, Yutaka; Kakuta, Seiji; Kusakabe, Katsuki; Abudula, Abuliti

    2013-07-01

    In order to understand the improvement effect of potassium (K) on the catalytic activity of iron-loaded calcined scallop shell (CS) for the steam reforming tar derived from biomass, various K precursors were applied for the catalyst preparation. It is found that pompom-like iron-based particles with a mesoporous structure were easily formed on the surface of calcined scallop shell (CS) when K2CO3 was used as K precursor while no such kind of microsphere was formed when other kinds of K precursors such as KOH and KNO3 were applied. The optimum K-loading amount for the preparation of this catalyst was investigated. Based on the experimental results obtained, a mechanism for the formation of these microspheres was proposed. This pompom-like potassium-promoted iron-based catalyst showed a better catalytic activity and reusability for the steam reforming of tar derived from lignin. Copyright © 2013 Elsevier Ltd. All rights reserved.

  8. Influence of calcination temperature in pozolanicity of gray sugar cane bagasse; Influencia da temperatura de calcinacao na pozolanicidade da cinza de bagaco de cana-de-acucar (CBCA))

    Energy Technology Data Exchange (ETDEWEB)

    Santos, T.A.; Argolo, R.A.; Andrade, H.M.C.; Ribeiro, D.V., E-mail: tiagoassuncao@hotmail.com [Universidade Federal da Bahia (UFBA), Salvador, BA (Brazil)

    2016-07-01

    BCA (Sugar Cane Bagasse) is burned in boilers in the process of electricity cogeneration causing the generation of CBCA (Gray Sugar Cane Bagasse), which is the final residue of sucroalcooeira industry. Currently, several studies seek alternative materials that can replace Portland cement, promoting discussions on the use of pozzolanic materials in cementitious matrices. Thus, this research seeks to analyze the pozzolanicity the CBCA, obtained by calcining the residue at different temperatures, to be determined by TG / DTG and DTA tests. For analysis of pozzolanicity these ashes were used electrical conductivity techniques, chemical titration NP EN 196-5, chapelle modified NBR 15895/2010 and the IAP method (Activity Index pozzolanic NBR:5752). The results obtained during the study demostraramm no difference between the ash calcined at temperatures of 500 ° C, 600 ° C and 700 ° C. (author)

  9. Superb adsorption capacity of hierarchical calcined Ni/Mg/Al layered double hydroxides for Congo red and Cr(VI) ions

    Energy Technology Data Exchange (ETDEWEB)

    Lei, Chunsheng [State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, Wuhan University of Technology, Wuhan 430070 (China); College of Environmental & Safety Engineering, Changzhou University, Changzhou 213164 (China); Zhu, Xiaofeng [College of Environmental & Safety Engineering, Changzhou University, Changzhou 213164 (China); Zhu, Bicheng; Jiang, Chuanjia; Le, Yao [State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, Wuhan University of Technology, Wuhan 430070 (China); Yu, Jiaguo, E-mail: jiaguoyu@yahoo.com [State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, Wuhan University of Technology, Wuhan 430070 (China); Department of Physics, Faculty of Science, King Abdulaziz University, Jeddah 21589 (Saudi Arabia)

    2017-01-05

    Highlights: • Ni/Mg/Al layered double hydroxides (NMA-LDHs) synthesized. • NMA-LDHs with hierarchically hollow microsphere structure. • Calcined NMA-LDHs have large adsorption capacities for CR and Cr(VI) ions. - Abstract: The preparation of hierarchical porous materials as catalysts and sorbents has attracted much attention in the field of environmental pollution control. Herein, Ni/Mg/Al layered double hydroxides (NMA-LDHs) hierarchical flower-like hollow microspheres were synthesized by a hydrothermal method. After the NMA-LDHs was calcined at 600 °C, NMA-LDHs transformed into Ni/Mg/Al layered double oxides (NMA-LDOs), which maintained the hierarchical flower-like hollow structure. The crystal phase, morphology, and microstructure of the as-prepared samples were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, energy-dispersive X-ray spectroscopy elemental mapping, Fourier transform infrared spectroscopy, and nitrogen adsorption−desorption methods. Both the calcined and non-calcined NMA-LDHs were examined for their performance to remove Congo red (CR) and hexavalent chromium (Cr(VI)) ions in aqueous solution. The maximum monolayer adsorption capacities of CR and Cr(VI) ions over the NMA-LDOs sample were 1250 and 103.4 mg/g at 30 °C, respectively. Thermodynamic studies indicated that the adsorption process was endothermic in nature. In addition, the addition of coexisting anions negatively influenced the adsorption capacity of Cr(VI) ions, in the following order: CO{sub 3}{sup 2−} > SO{sub 4}{sup 2−} > H{sub 2}PO{sub 4}{sup −} > Cl{sup −}. This work will provide new insight into the design and fabrication of advanced adsorption materials for water pollutant removal.

  10. ICPP calcined solids storage facility closure study. Volume II: Cost estimates, planning schedules, yearly cost flowcharts, and life-cycle cost estimates

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1998-02-01

    This document contains Volume II of the Closure Study for the Idaho Chemical Processing Plant Calcined Solids Storage Facility. This volume contains draft information on cost estimates, planning schedules, yearly cost flowcharts, and life-cycle costs for the four options described in Volume I: (1) Risk-Based Clean Closure; NRC Class C fill, (2) Risk-Based Clean Closure; Clean fill, (3) Closure to landfill Standards; NRC Class C fill, and (4) Closure to Landfill Standards; Clean fill.

  11. Reutilization of low-grade magnesium oxides for flue gas desulfurization during calcination of natural magnesite: A closed-loop process

    OpenAIRE

    del Valle Zermeño, Ricardo; Formosa Mitjans, Joan; Aparicio, J.A,; Chimenos Ribera, Josep Maria

    2014-01-01

    The European Commission is encouraging the Cement, Lime and Magnesium Oxide Manufacturing Industries to reutilize collected particulate matter or wastes in the emission control of SO2 with a 100% removal efficiency. Following this directive, three different by-products from the calcination of natural magnesite were selected in order to evaluate their desulfurization capacity. The saturation time, defined as the time for the total neutralization of SO2 was used to determine consumption values ...

  12. The effect of calcination temperature on the capacitive properties of WO3-based electrochemical capacitors synthesized via a sol-gel method

    Science.gov (United States)

    Susanti, Diah; Wibawa, Rizky Narendra Dwi; Tananta, Lucky; Purwaningsih, Hariyati; Fajarin, Rindang; Kusuma, George Endri

    2013-12-01

    Electrochemical capacitor (EC) is a promising energy storage device which can be hybridized with other energy conversion or energy storage devices. One type of ECs is pseudocapacitor made of metal oxides. WO3 is an inexpensive semiconductor metal oxide which has many applications. However the application of WO3 as an EC material was rarely reported. Therefore in this research EC was prepared from WO3 nanomaterial synthesized by a sol-gel process. The WO3 gel was spin-coated on graphite substrates and calcined at various temperatures of 300°C, 400°C, 500°C and 600°C for 1 h. Cyclic voltammetry (CV) measurements were used to observe the capacitive property of the WO3 samples. SEM, XRD, FTIR and Brunauer-Emmett-Teller (BET) analyses were used to characterize the material structures. WO3 calcined at 400°C was proved to have the highest capacitance of 233.63 F·g-1 (1869 mF·cm-2) at a scan rate of 2 mV·s-1 in 1 mol/L H2SO4 between potentials -0.4 and 0.4 V vs. SCE. Moreover it also showed the most symmetric CV curves as the indication of a good EC. Hence WO3 calcined at 400°C is a potential candidate for EC material of pseudocapacitor type.

  13. The extraction of rare earth elements from ICPP sodium-bearing waste and dissolved zirconium calcine by CMP and TRUEX solvents

    Energy Technology Data Exchange (ETDEWEB)

    Todd, T.A.; Glagolenko, I.Y.; Herbst, R.S.; Brewer, K.N.

    1995-11-01

    The extraction of stable isotopes of Eu and Ce was investigated from simulated sodium-bearing waste (SBW) and dissolved zirconium calcine by TRUEX and CMP solvents at the Idaho Chemical Processing Plant (ICPP). Single batch contacts were carried out in order to evaluate the rare earth behavior in the extraction, scrub, strip and wash sections for the proposed flowsheets. It has been shown that these lanthanides are efficiently extracted from the sodium-bearing wastes into either solvent, are not scrubbed and are stripped from both of the extractants with dilute HEDPA. The extraction distribution coefficients for Ce and Eu are higher in the TRUEX solvent (D{sub Ce} = 11.7, D{sub Eu} = 14.9) compared with CMP (D{sub Ce} = 9.3, D{sub Eu} = 7.23) for SBW. The extraction distribution coefficients for Ce and Eu are considerably less in the TRUEX solvent (D{sub Ce}=1.13, D{sub Eu}=1.8) than in the CMP solvent (D{sub Ce}=7.4, D{sub Eu=}6.1) for dissolved zirconium calcine feeds. The lower distribution coefficients for the extraction of lanthanides in the TRUEX/dissolved zirconium calcine system can be explained by zirconium loading of the solvent. The data obtained also confirmed that Ce and Eu can be used as non-radioactive surrogates for Am in separation experiments with acidic solutions.

  14. Occupational exposure to carbon/coke fibers in plants that produce green or calcined petroleum coke and potential health effects: 2. Fiber concentrations.

    Science.gov (United States)

    Maxim, L Daniel; Galvin, Jennifer B; Niebo, Ron; Segrave, Alan M; Kampa, Otto A; Utell, Mark J

    2006-01-01

    We monitored exposure to various fibers among workers in eight plants operated by ConocoPhillips that produce green or calcined petroleum coke. Carbon/coke and other fibers, including calcium silicate, cellulose, gypsum, and iron silicate, were found in occupational samples. Carbon/coke fibers were found in bulk samples of calcined petroleum coke, the probable source of these fibers in occupational samples. Time-weighted average (TWA) total fiber concentrations were approximately lognormally distributed; 90% were fiber concentrations varied with plant, job (tasks), and type of coke. This was expected given the substantial differences in plant configuration, technology, and workplace practices among refineries and carbon plants. Carbon/coke fibers (identified and measured using transmission electron microscopy [TEM]) were found at all plants producing all types of calcined coke and not detected at any plant producing only green coke. Approximately 98% of all carbon/coke TWAs were carbon/coke TLA is certainly < or = 0.05 f/ml and probably < 0.03 f/ml.

  15. RELATIONSHIPS BETWEEN SOIL MICROBIAL BIOMASS, AGGREGATE STABILITY AND AGGREGATE ASSOCIATED-C: A MECHANISTIC APPROACH

    Directory of Open Access Journals (Sweden)

    Patrizia Guidi

    2014-01-01

    Full Text Available For the identification of C pools involved in soil aggregation, a physically-based aggregate fractionation was proposed, and  additional pretreatments were used in the measurement of the 1-2 mm aggregate stability in order to elucidate the relevance of the role of soil microorganisms with respect to the different aggregate breakdown mechanisms. The study was carried out on three clay loam Regosols, developed on calcareous shales, known history of organic cultivation.Our results showed that the soil C pool controlling the process of stabilisation of aggregates was related to the microbial community. We identified the resistance to fast wetting as the major mechanism of aggregate stability driven by microorganims. The plausible hypothesis is that organic farming promotes fungi growth, improving water repellency of soil aggregates by fungal hydrophobic substances. By contrast, we failed in the identification of C pools controlling the formation of aggregates, probably because of the disturbance of mechanical tillage which contributes to the breakdown of soil aggregates.The physically-based aggregate fractionation proposed in this study resulted useful in the  mechanistically understanding of the role of microorganisms in soil aggregation and it might be suggested for studying the impact of management on C pools, aggregates properties and their relationships in agricultural soils.

  16. Determinants of Aggregate Agricultural Productivity among High ...

    African Journals Online (AJOL)

    The main purpose of this study was to isolate and discuss the determinants of aggregate agricultural productivity in an environment where policy on subsidy of fertilizer is inconsistent. The study examined determinants of aggregate agricultural productivity among HEIT farmers in Imo State, in order to provide information on ...

  17. Interface-Based Service Composition with Aggregation

    DEFF Research Database (Denmark)

    Dalla Preda, Mila; Gabbrielli, Maurizio; Guidi, Claudio

    2012-01-01

    . In this paper we generalise this composition mechanism by identifying the primitive notion of aggregation. We formally define the semantics of aggregation in terms of a process calculus. We also provide a reference implementation for this primitive by extending the Jolie language, thus allowing...

  18. 12 CFR 1402.27 - Aggregating requests.

    Science.gov (United States)

    2010-01-01

    ... 12 Banks and Banking 7 2010-01-01 2010-01-01 false Aggregating requests. 1402.27 Section 1402.27... Information § 1402.27 Aggregating requests. A requester may not file multiple requests at the same time, each... in concert, is attempting to break a request down into a series of requests for the purpose of...

  19. 32 CFR 701.46 - Aggregating requests.

    Science.gov (United States)

    2010-07-01

    ... 32 National Defense 5 2010-07-01 2010-07-01 false Aggregating requests. 701.46 Section 701.46... THE NAVY DOCUMENTS AFFECTING THE PUBLIC FOIA Fees § 701.46 Aggregating requests. Except for requests... for the first 100 pages of reproduction. However, a requester may not file multiple requests at the...

  20. Biomass round bales infield aggregation logistic scenarios

    Science.gov (United States)

    Biomass bales often need to be aggregated (collected into groups and transported) to a field-edge stack for temporary storage for feedlots or processing facilities. Aggregating the bales with the least total distance involved is a goal of producers and bale handlers. Several logistics scenarios for ...

  1. On Aggregating Human Capital Across Heterogeneous Cohorts

    DEFF Research Database (Denmark)

    Growiec, Jakub; Groth, Christian

    Based on a general framework for computing the aggregate human capital stock under heterogeneity across population cohorts, the paper derives aggregate human capital stocks in the whole population and in the labor force, and relates these variables to average years of schooling and average work...

  2. A vertically resolved model for phytoplankton aggregation

    Indian Academy of Sciences (India)

    Simple experiments demonstrate the effects of aggregation on the timing and depth distribution of primary production and export. A more detailed ecological model is applied to sites in the Arabian Sea; it demonstrates that aggregation can be important for deep sedimentation even when its effect on surface concentrations ...

  3. Teaching Aggregate Demand and Supply Models

    Science.gov (United States)

    Wells, Graeme

    2010-01-01

    The author analyzes the inflation-targeting model that underlies recent textbook expositions of the aggregate demand-aggregate supply approach used in introductory courses in macroeconomics. He shows how numerical simulations of a model with inflation inertia can be used as a tool to help students understand adjustments in response to demand and…

  4. 24 CFR 50.21 - Aggregation.

    Science.gov (United States)

    2010-04-01

    ... 24 Housing and Urban Development 1 2010-04-01 2010-04-01 false Aggregation. 50.21 Section 50.21 Housing and Urban Development Office of the Secretary, Department of Housing and Urban Development... Aggregation. Activities which are geographically related and are logical parts of a composite of contemplated...

  5. Aggregation and fibrillation of bovine serum albumin

    DEFF Research Database (Denmark)

    Holm, NK; Jespersen, SK; Thomassen, LV

    2007-01-01

    The all-alpha helix multi-domain protein bovine serum albumin (BSA) aggregates at elevated temperatures. Here we show that these thermal aggregates have amyloid properties. They bind the fibril-specific dyes Thioflavin T and Congo Red, show elongated although somewhat worm-like morphology and cha...

  6. Practical Certificateless Aggregate Signatures From Bilinear Maps

    NARCIS (Netherlands)

    Gong, Zheng; Long, Y.; Hong, X.; Chen, Kefei

    2010-01-01

    Aggregate signature is a digital signature with a striking property that anyone can aggregate n individual signatures on n different messages which are signed by n distinct signers, into a single compact signature to reduce computational and storage costs. In this work, two practical certificateless

  7. Griseofulvin-induced aggregation of microtubule protein.

    Science.gov (United States)

    Roobol, A; Gull, K; Pogson, C I

    1977-01-01

    Griseofulvin (7-chloro-2',4,6-trimethoxy-6'-methylspiro[benzofuran-2(3H),1'-[2]cyclohexene]-3,4'-dione) induces aggregation of microtubule protein at 0 degrees C. This aggregate contains approx. 90% of the microtubule-associated proteins originally present in the microtubule protein. The supernatant obtained after removal of the griseofulvin-induced aggregate does not form microtubules on warming at 37 degrees C. Addition of the griseofulvin-aggregated protein to this supernatant and warming to 37 degrees C gives rise to a limited amount of microtubule assembly. The possible involvement of griseofulvin-induced aggregation of microtubule protein at 0 degrees C in the inhibition by griseofulvin of microtubule assembly in vitro is discussed. Images PLATE 1 PLATE 2 PMID:588267

  8. Aggregation of sodium alkylbenzenesulfonates in aqueous solution

    Energy Technology Data Exchange (ETDEWEB)

    Magid, L.J.; Shaver, R.J.; Gulari, E.; Bedwell, B.; Alkhafaji, S.

    1981-01-01

    The surfactant 6 phenyl C/sub 12/SNa forms small spherical micelles in aqueous solution, having an aggregation number of 20 to 30 and a fractional charge of 0.45. These micelles are hydrated to the extent of approximately 18 moles H/sub 2/O per moles of surfactant. A second larger aggregate is also present in 6 phenyl C/sub 12/SNa solutions; its importance increases with solution age. Addition of NaCl causes both aggregates to apparently increase modestly in size. The surfactant 8 phenyl C/sub 16/SNa also contains both aggregates in its solutions; the larger one is relatively more important here. The larger aggregate does not correspond to dispersed bits of a liquid crystalline mesophase.

  9. Protein aggregates stimulate macropinocytosis facilitating their propagation.

    Science.gov (United States)

    Yerbury, Justin J

    2016-03-03

    Temporal and spatial patterns of pathological changes such as loss of neurons and presence of pathological protein aggregates are characteristic of neurodegenerative diseases such as Amyotrophic Lateral Sclerosis, Frontotemporal Dementia, Alzheimer's disease and Parkinson's disease. These patterns are consistent with the propagation of protein misfolding and aggregation reminiscent of the prion diseases. There is a surge of evidence that suggests that large protein aggregates of a range of proteins are able to enter cells via macropinocytosis. Our recent work suggests that this process is activated by the binding of aggregates to the neuron cell surface. The current review considers the potential role of cell surface receptors in the triggering of macropinocytosis by protein aggregates and the possibility of utilizing macropinocytosis pathways as a therapeutic target.

  10. Ratio-Based Gradual Aggregation of Data

    DEFF Research Database (Denmark)

    Iftikhar, Nadeem

    2012-01-01

    cause data management and data storage issues. However, non-flexible and ineffective means of data aggregation not only reduce performance of database queries but also lead to erroneous reporting. This paper presents flexible and effective ratio-based methods for gradual data aggregation in databases....... Gradual data aggregation is a process that reduces data volume by converting the detailed data into multiple levels of summarized data as the data gets older. This paper also describes implementation strategies of the proposed methods based on standard database technology.......Majority of databases contain large amounts of data, gathered over long intervals of time. In most cases, the data is aggregated so that it can be used for analysis and reporting purposes. The other reason of data aggregation is to reduce data volume in order to avoid over-sized databases that may...

  11. Effect of calcination temperature on structure and photocatalytic activity under UV and visible light of nanosheets from low-cost magnetic leucoxene mineral

    Science.gov (United States)

    Charerntanom, Wissanu; Pecharapa, Wisanu; Pavasupree, Suttipan; Pavasupree, Sorapong

    2017-07-01

    This research has experimentally synthesized the nanosheets from the naturally-mineral magnetic leucoxene under the hydrothermal synthesis condition of 105 °C for 24 h. Magnetic leucoxene was utilized as the starting material due to its high TiO2 content (70-80%) and inexpensiveness. The characterization of the synthesized nanosheets was subsequently carried out: the crystalline structure, the chemical composition, the shape, the size and the specific surface area, by the X-ray diffraction (XRD), X-ray fluorescence (XRF), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and Brunauer-Emmett-Teller (BET) specific surface area analysis. The analysis results indicated that the starting magnetic leucoxene is of rutile phase while the synthesized nanosheets are of titanate structure (H2TixO2x + 1). After calcination at the temperature range of 300 and 400 °C, the calcined samples demonstrated TiO2 (B). At 500 and 600 °C, the calcined nanosheets revealed a bi-crystalline mixture consisting of TiO2 (B) and anatase TiO2. At 700-1000 °C, the crystalline structure shows anatase and rutile phase. At 1100 °C, the prepared samples consisted of a mixture of anatase, rutile phase of TiO2, and Fe2O3 phase. The synthesized product also exhibited the flower-like morphology with 2-5 μm in diameter, and the nanosheets structure was slightly curved, with 100 nm to 2 μm in width and 1-3 nm in thickness. At 100-200 °C showed sheets-like structure. At 300-1100 °C, the calcined nanosheets became unstable and began to decompose and transform into nanoparticles. The increasing size of nanoparticle decreased the specific surface area of the nanosheets, caused by increasing calcination temperature. Furthermore, the BET specific surface area of the nanosheets was approximately 279.8 m2/g. More importantly, the synthesized nanosheets achieved the higher photocatalytic activity under UV and visible light than did the commercial TiO2 nanoparticles (JRC-01, JRC-03

  12. Sans study of asphaltene aggregation

    Energy Technology Data Exchange (ETDEWEB)

    Overfield, R.E.; Sheu, E.Y.; Sinha, S.K.; Liang, K.S. (Esso Resources Canada Ltd., 339-50 Avenue S.E., Calgary, Alberta T2G 2B3 (CA))

    1988-06-01

    The colloidal properties of asphaltenes have long been recognized from peculiarities in their solubility and colligative properties. A layered micellar model or asphaltenes was proposed by others in which a highly condensed alkyl aromatic formed the central part, and molecules of decreasingly aromatic character (resins) clustered around them. Numerous studies, based on a variety of techniques such as ultracentrifugation and electron microscopy indicated a particulate nature for asphaltenes with size 20-40 A diameter. Others have proposed a refined model based on x-ray diffraction and small angle scattering. In this model, interactions between flat sheets of condensed aromatic rings form the central ''crystallite'' part of a spherical particle with the outer part being comprised of the aliphatic positions of the same molecules. These particles are bunched together with some degree of entanglement into ''micelles''. Concentration and solvent dependent radii of gyration, ranging from 30-50 A were reported. The aggregation creates a good deal of uncertainty as to the true molecular size or weight of asphaltenes. Neutron scattering offers novel contrast relative to light scattering (refractive index) and x-ray scattering (electron density). This is because the scattering length of proton is negative, whereas that from deuterium and other nuclei such as C, S, O, and N are positive. Thus by replacing hydrogen with deuterium in either the solvent or the scatterer the contrast can be varied, and different parts of the molecule can be highlighted.

  13. Congested Aggregation via Newtonian Interaction

    Science.gov (United States)

    Craig, Katy; Kim, Inwon; Yao, Yao

    2017-08-01

    We consider a congested aggregation model that describes the evolution of a density through the competing effects of nonlocal Newtonian attraction and a hard height constraint. This provides a counterpoint to existing literature on repulsive-attractive nonlocal interaction models, where the repulsive effects instead arise from an interaction kernel or the addition of diffusion. We formulate our model as the Wasserstein gradient flow of an interaction energy, with a penalization to enforce the constraint on the height of the density. From this perspective, the problem can be seen as a singular limit of the Keller-Segel equation with degenerate diffusion. Two key properties distinguish our problem from previous work on height constrained equations: nonconvexity of the interaction kernel (which places the model outside the scope of classical gradient flow theory) and nonlocal dependence of the velocity field on the density (which causes the problem to lack a comparison principle). To overcome these obstacles, we combine recent results on gradient flows of nonconvex energies with viscosity solution theory. We characterize the dynamics of patch solutions in terms of a Hele-Shaw type free boundary problem and, using this characterization, show that in two dimensions patch solutions converge to a characteristic function of a disk in the long-time limit, with an explicit rate on the decay of the energy. We believe that a key contribution of the present work is our blended approach, combining energy methods with viscosity solution theory.

  14. Role of Mg{sub x}Ca{sub 1−x}CO{sub 3} on the physical–chemical properties and cyclic CO{sub 2} capture performance of dolomite by two-step calcination

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Ke; Han, Dongtai, E-mail: handongtai@cumt.edu.cn; Zhao, Pengfei, E-mail: zhaopfcumt@163.com; Hu, Xiumeng; Yin, Zeguang; Wu, Di

    2015-08-20

    Highlights: • Two-step calcination treated dolomite sorbent was prepared and characterized. • An intermediate phase (Mg{sub x}Ca{sub 1−x}CO{sub 3}) was observed by TG and XRD results. • Mg-calcite hindered the de-mixing of Ca and Mg. • Smaller grains, larger specific surface area and pore volume were obtained. • This favorable structure resulted in a high and stable CO{sub 2} capture performance. - Abstract: Two-step calcination (CO{sub 2} and N{sub 2} atmospheres) was used to modify the microstructure of natural dolomite for high-temperature CO{sub 2} capture. Two other one-step calcinations (CO{sub 2} or N{sub 2} atmosphere) were provided for comparison. Different morphological characterizations (thermal decomposition, phase composition, morphology, and nitrogen adsorption) were performed, followed by an analysis of 30 carbonation/calcination cycles in a fixed bed reactor. During primary calcination in a CO{sub 2} atmosphere, an intermediate phase (Mg{sub x}Ca{sub 1−x}CO{sub 3}) was observed by TG and XRD results, which hindered the de-mixing of CaO and MgO in the secondary calcination in a N{sub 2} atmosphere. Therefore, two-step calcination produced smaller grains (CaO: 45.2 nm; MgO: 32.6 nm), larger specific surface area (21.08 m{sup 2}/g) and pore volume (0.082 cm{sup 3}/g) and uniform distribution of CaO and MgO, which resulted in a higher and more stable uptake of CO{sub 2} compared to the results from one-step calcinations.

  15. Influence of calcination temperature on Cd{sub 0.3}Co{sub 0.7}Fe{sub 2}O{sub 4} nanoparticles: Structural, thermal and magnetic properties

    Energy Technology Data Exchange (ETDEWEB)

    Reddy, Ch.Venkata, E-mail: cvrphy@gmail.com [School of Mechanical Engineering, Yeungnam University, 214-1, Dae-dong, Gyeongsan-si, Gyeongsangbuk-do 712-749 (Korea, Republic of); PrabhakarVattikuti, S.V. [School of Mechanical Engineering, Yeungnam University, 214-1, Dae-dong, Gyeongsan-si, Gyeongsangbuk-do 712-749 (Korea, Republic of); Ravikumar, R.V.S.S.N. [Department of Physics, Acharya Nagarjuna University, AP 522510 (India); Moon, Sang Jun, E-mail: nanobiomems@dgist.ac.kr [Cybernetics Laboratory, Daegu Gyeongbuk Institute of Science and Technology (DGIST) (Korea, Republic of); Shim, Jaesool, E-mail: jshim@ynu.ac.kr [School of Mechanical Engineering, Yeungnam University, 214-1, Dae-dong, Gyeongsan-si, Gyeongsangbuk-do 712-749 (Korea, Republic of)

    2015-11-15

    Cadmium substituted cobalt ferrite nanoparticles are synthesis using the chemical method. The as-prepared ferrite nanoparticles are calcinated at 300 °C and 600 °C respectively. The samples are studied using; Powder XRD, SEM with EDX, TEM, FT-IR, TG-DTA and vibrating sample magnetometer (VSM) in order to study the calcination temperature effect on structural, morphological and magnetic properties. The magnetic properties, like saturation magnetization and coercivity increases with increasing the calcination temperature. This enhancement is attributed to the transition from amulti-domain to a single-domain nature. The absorption bands observed at 588 cm{sup −1} (ν{sub 1}) and 440 cm{sup −1} (ν{sub 2}) are attributed to the vibrations of tetrahedral and octahedral complexes. The TG-DTA curves reveal the thermal stability of the prepared ferrite nanoparticles. The calcination temperature influences the magnetic properties, surface morphology and crystalline size. - Highlights: • Cd{sub 0.3}Co{sub 0.7}Fe{sub 2}O{sub 4} nanoparticles synthesized using the chemical co-precipitation. • The magnetization, coercivity values increases with increasing the calcination temperature. • The calcination temperature influences the magnetic properties and crystallite size. • The FTIR spectra results confirmed the vibrations of tetrahedral and octahedral complexes.

  16. Aggregation of volcanic ash in explosive eruptions

    Science.gov (United States)

    Telling, J. W.; Dufek, J.

    2009-12-01

    We present the result of a recent experimental and numerical investigation of ash aggregation in volcanic plumes. Eruption dynamics are sensitive to microphysical processes, like ash aggregation, yet are difficult to parameterize based on dynamics simulations of whole eruption columns due to the lack of sufficient resolution. Here we present the results of experiments that develop a probabilistic relationship for ash aggregation based on impact velocity and atmospheric conditions (water vapor and atmospheric pressure). The probabilistic relationship can be integrated, in conjunction with a reconstructed velocity distribution of the ash in the column, and then can be readily incorporated in large-scale simulations of eruption column behavior. We also conduct detailed Eulerian-Lagrangian simulations at the scale of our experiment as a test of the ash aggregation relationship. The physical experiment was carried out in a contained tank designed to allow for the control of ‘atmospheric’ conditions. The tank can be depressurized as needed, using the gas inlet and the attached vacuum pump, and the ambient humidity can be altered by adjusting the gas mixture at the inlet. Image data is recorded with a high speed camera and post-processed to determine the number of collisions, energy of collisions and probability of aggregation. We will present the results of aggregation probability and the effects of incorporating these results into a multiphase model of a three-dimensional eruption column, where the effects of ash aggregation are especially important in regions of high shear and high granular temperature.

  17. Seasonal variability of soil aggregate stability

    Science.gov (United States)

    Rohoskova, M.; Kodesova, R.; Jirku, V.; Zigova, A.; Kozak, J.

    2009-04-01

    Seasonal variability of soil properties measured in surface horizons of three soil types (Haplic Luvisol, Greyic Phaeozem, Haplic Cambisol) was studied in years 2007 and 2008. Undisturbed and disturbed soil samples were taken every month to evaluate field water content, bulk density, porosity, ration of gravitational and capillary pores, pHKCl and pHH2O, organic matter content and its quality, aggregate stability using WSA index. In addition, micromorphological features of soil aggregates were studied in thin soil sections that were made from undisturbed large soil aggregates. Results showed that soil aggregate stability depended on stage of the root zone development, soil management and climatic conditions. Larger aggregate stabilities and also larger ranges of measure values were obtained in the year 2007 then those measured in 2008. This was probably caused by lower precipitations and consequently lower soil water contents observed in 2007 than those measured in 2008. The highest aggregate stability was measured at the end of April in the years 2007 and 2008 in Haplic Luvisol and Greyic Phaeozem, and at the end of June in the year 2007 and at the beginning of June in 2008 in Haplic Cambisol. In all cases aggregate stability increased during the root growth and then gradually decreased due to summer rainfall events. Aggregate stability reflected aggregate structure and soil pore system development, which was documented on micromorphological images and evaluated using the ration of gravitational and capillary pores measured on the undisturbed sol samples. Acknowledgement: Authors acknowledge the financial support of the Grant Agency of the Czech Republic grant No. 526/08/0434, and the Ministry of Education, Youth and Sports grant No. MSM 6046070901.

  18. Exciton dynamics in perturbed vibronic molecular aggregates

    Directory of Open Access Journals (Sweden)

    C. Brüning

    2016-07-01

    Full Text Available A site specific perturbation of a photo-excited molecular aggregate can lead to a localization of excitonic energy. We investigate this localization dynamics for laser-prepared excited states. Changing the parameters of the electric field significantly influences the exciton localization which offers the possibility for a selective control of this process. This is demonstrated for aggregates possessing a single vibrational degree of freedom per monomer unit. It is shown that the effects identified for the molecular dimer can be generalized to larger aggregates with a high density of vibronic states.

  19. Programming spiders, bots, and aggregators in Java

    CERN Document Server

    Heaton, Jeff

    2006-01-01

    The content and services available on the web continue to be accessed mostly through direct human control. But this is changing. Increasingly, users rely on automated agents that save them time and effort by programmatically retrieving content, performing complex interactions, and aggregating data from diverse sources. Programming Spiders, Bots, and Aggregators in Java teaches you how to build and deploy a wide variety of these agents-from single-purpose bots to exploratory spiders to aggregators that present a unified view of information from multiple user accounts. You will quickly build on

  20. Insulin aggregation tracked by its intrinsic TRES

    Science.gov (United States)

    Chung, Li Hung C.; Birch, David J. S.; Vyshemirsky, Vladislav; Ryadnov, Maxim G.; Rolinski, Olaf J.

    2017-12-01

    Time-resolved emission spectra (TRES) have been used to detect conformational changes of intrinsic tyrosines within bovine insulin at a physiological pH. The approach offers the ability to detect the initial stages of insulin aggregation at the molecular level. The data analysis has revealed the existence of at least three fluorescent species undergoing dielectric relaxation and significant spectral changes due to insulin aggregation. The results indicate the suitability of the intrinsic TRES approach for insulin studies and for monitoring its stability during storage and aggregation in insulin delivery devices.

  1. Synchronized Data Aggregation for Wireless Sensor Network

    DEFF Research Database (Denmark)

    Dnyaneshwar, Mantri; Prasad, Neeli R.; Prasad, Ramjee

    2014-01-01

    Wireless Sensor Networks (WSNs) are used for monitoring and data collection purposes. A key challenge in effective data collection is to schedule and synchronize the activities of the nodes with global clock. This paper proposes the Synchronized Data Aggregation Algorithm (SDA) using spanning tree...... mechanism. It provides network-wide time synchronization for sensor network. In the initial stage algorithm established the hierarchical structure in the network and then perform the pair - wise synchronization. SDA aggregate data with a global time scale throughout the network. The aggregated packets...

  2. Patterns of [PSI+] aggregation allow insights into cellular organization of yeast prion aggregates

    Science.gov (United States)

    Tyedmers, Jens

    2012-01-01

    The yeast prion phenomenon is very widespread and mounting evidence suggests that it has an impact on cellular regulatory mechanisms related to phenotypic responses to changing environments. Studying the aggregation patterns of prion amyloids during different stages of the prion life cycle is a first key step to understand major principles of how and where cells generate, organize and turn-over prion aggregates. The induction of the [PSI+] state involves the actin cytoskeleton and quality control compartments such as the Insoluble Protein Deposit (IPOD). An initially unstable transitional induction state can be visualized by overexpression of the prion determinant and displays characteristic large ring- and ribbon-shaped aggregates consisting of poorly fragmented bundles of very long prion fibrils. In the mature prion state, the aggregation pattern is characterized by highly fragmented, shorter prion fibrils that form aggregates, which can be visualized through tagging with fluorescent proteins. The number of aggregates formed varies, ranging from a single large aggregate at the IPOD to multiple smaller ones, depending on several parameters discussed. Aggregate units below the resolution of light microscopy that are detectable by fluorescence correlation spectroscopy are in equilibrium with larger aggregates in this stage and can mediate faithful inheritance of the prion state. Loss of the prion state is often characterized by reduced fragmentation of prion fibrils and fewer, larger aggregates. PMID:22449721

  3. p53 Aggregates penetrate cells and induce the co-aggregation of intracellular p53.

    Directory of Open Access Journals (Sweden)

    Karolyn J Forget

    Full Text Available Prion diseases are unique pathologies in which the infectious particles are prions, a protein aggregate. The prion protein has many particular features, such as spontaneous aggregation, conformation transmission to other native PrP proteins and transmission from an individual to another. Protein aggregation is now frequently associated to many human diseases, for example Alzheimer's disease, Parkinson's disease or type 2 diabetes. A few proteins associated to these conformational diseases are part of a new category of proteins, called prionoids: proteins that share some, but not all, of the characteristics associated with prions. The p53 protein, a transcription factor that plays a major role in cancer, has recently been suggested to be a possible prionoid. The protein has been shown to accumulate in multiple cancer cell types, and its aggregation has also been reproduced in vitro by many independent groups. These observations suggest a role for p53 aggregates in cancer development. This study aims to test the «prion-like» features of p53. Our results show in vitro aggregation of the full length and N-terminally truncated protein (p53C, and penetration of these aggregates into cells. According to our findings, the aggregates enter cells using macropinocytosis, a non-specific pathway of entry. Lastly, we also show that once internalized by the cell, p53C aggregates can co-aggregate with endogenous p53 protein. Together, these findings suggest prion-like characteristics for p53 protein, based on the fact that p53 can spontaneously aggregate, these aggregates can penetrate cells and co-aggregate with cellular p53.

  4. Rheology and zeta potential of cement pastes containing calcined silt and ground granulated blast-furnace slag

    Directory of Open Access Journals (Sweden)

    Safi, B.

    2011-09-01

    Full Text Available This study aimed to analyse the re-use of dam silt as a supplementary binder for self-compacting concrete (SCC. When burnt, silt becomes more reactive because the kaolin it contains is converted into metakaolin. Portland cement, calcined or burnt silt and ground granulated blast furnace slag were used in this research. Cement pastes were prepared with blends containing two or three of these materials. The replacement ratio for burnt silt in both cases was 10 % and 20 % by cement weight and the ratio for the slag was a constant 30 % by weight of the blend. Rheological and zeta potential tests were conducted to evaluate paste electrokinetics and rheological behaviour. The findings showed that burnt silt is apt for use as an addition to cement for SCC manufacture.

    En el presente trabajo se ha analizado la posibilidad de utilizar los lodos procedentes de embalses como adición en la fabricación del hormigón autocompactante (HAC. Con la calcinación, estos materiales se vuelven más reactivos debido a la transformación en metacaolín, del caolín que forma parte de su composición. Las materias primas empleadas en esta investigación son: cemento Pórtland, lodos de embalse calcinados y escorias granuladas de horno alto. Se prepararon pastas de cemento con mezclas que contenían dos o tres de estos materiales. El porcentaje de reemplazo de los lodos calcinados osciló entre el 10 y el 20 % en peso del cemento, mientras que el de la escoria fue del 30 % en peso de la mezcla. Se llevaron a cabo ensayos reológicos y de potencial zeta para evaluar el comportamiento electrocinético y reológico de las distintas pastas. De acuerdo con los resultados obtenidos, una vez calcinados, los lodos de embalse son aprovechables como adición al cemento con destino a la preparación de HAC.

  5. Characteristics of Commercial SiC and Synthetic SiC as an Aggregate in Geopolymer Composites

    Science.gov (United States)

    Irfanita, R.; Afifah, K. N.; Asrianti; Subaer

    2017-03-01

    This main objective of this study is to investigate the effect silicon carbide (SiC) as an aggregate on the mechanical strength and microstructure of the geopolymer composites. The geopolymers binder were produced by using alkaline activation method of metakaolin and cured at 70oC for 2 hours. In this study commercial and synthetic SiC were used as aggregate to produce composite structure. Synthetic SiC was produced from rice husk ash and coconut shell carbon calcined at 750oC for 2 hours. The addition of SiC in geopolymers paste was varied from 0.25g, 0.50g to 0.75g to form geopolymers composites. The chemical compositions and crystallinity level of SiC and the resulting composites were measured by means of Rigaku MiniFlexII X-Ray Diffraction (XRD). The microstructure of SiC and the composites were examined by using Tescan Vega3SB Scanning Electron Microscopy (SEM). The physical and mechanical properties of the samples were determined based on apparent porosity, bulk density, and three bending flexural strength measurements. The results showed that the commercial and synthetic SiC were effectively produced geopolymers composites with different microstructure, physical and mechanical strength.

  6. Geopolymerization of lightweight aggregate waste

    Directory of Open Access Journals (Sweden)

    Labrincha, J. A.

    2008-09-01

    Full Text Available Geopolymerization is a viable way to process and re-use alumino-silicate industrial waste while producing highstrength, high chemical inertia materials that can effectively immobilize other industrial by-products, and even hazardous waste. In this study industrial waste from different stages of the manufacture of lightweight expanded clay aggregate was characterized for its possible transformation, via alkali activation, to geopolymers. The ultimate aim was to assess the possibility of using such geopolymers to develop thermal and acoustic insulation panels. The containment of hazardous materials is another important application for these new materials. Geopolymers were prepared for this study with different particles size distributions and activator concentrations. Their mechanical properties, composition and microstructure were characterized and a material with promising insulating properties was produced. A preliminary analysis was conducted of the salt formation observed in these geopolymers, the chief drawback to their use.La geopolimerización es una manera viable para procesar y agregar valor a los residuos industriales de alumino-silicato dando lugar a materiales con elevadas resistencias mecánmicas, alta inercia química y que permiten encapsular otros residuos, incluso peligrosos. Los residuos industriales que proceden de diversos tipos de arcillas para la fabricación de áridos ligeros se han caracterizado para la producción de geopolímeros mediante el proceso de ataque alcalino. Su incorporación en una matriz geopolimérica permite la posibilidad de desarrollo de paneles de aislamiento (térmico y acústico. Además, la inmovilización de materiales peligrosos es un logro adicional importante. Los geopolímeros se han producido con fórmulas diferentes y se han caracterizado sus propiedades mecánicas, composición y microestructura, para dar lugar a una composición interesante con propiedades aislantes. Se ha llevado a cabo

  7. Suspensions of colloidal particles and aggregates

    CERN Document Server

    Babick, Frank

    2016-01-01

    This book addresses the properties of particles in colloidal suspensions. It has a focus on particle aggregates and the dependency of their physical behaviour on morphological parameters. For this purpose, relevant theories and methodological tools are reviewed and applied to selected examples. The book is divided into four main chapters. The first of them introduces important measurement techniques for the determination of particle size and interfacial properties in colloidal suspensions. A further chapter is devoted to the physico-chemical properties of colloidal particles—highlighting the interfacial phenomena and the corresponding interactions between particles. The book’s central chapter examines the structure-property relations of colloidal aggregates. This comprises concepts to quantify size and structure of aggregates, models and numerical tools for calculating the (light) scattering and hydrodynamic properties of aggregates, and a discussion on van-der-Waals and double layer interactions between ...

  8. Probing colloidal particle aggregation by light scattering.

    Science.gov (United States)

    Trefalt, Gregor; Szilagyi, Istvan; Oncsik, Tamas; Sadeghpour, Amin; Borkovec, Michal

    2013-01-01

    The present article reviews recent progress in the measurement of aggregation rates in colloidal suspensions by light scattering. Time-resolved light scattering offers the possibility to measure absolute aggregation rate constants for homoaggregation as well as heteroaggregation processes. We further discuss the typical concentration dependencies of the aggregation rate constants on additives. Addition of simple salts containing monovalent counterions leads to screening of the electrostatic repulsion of the charged particles and a transition from slow to rapid aggregation. Addition of salts containing multivalent counterions may lead to a charge reversal, which results in a sequence of two instability regions. Heteroaggregation rates between oppositely charged particles decrease with increasing salt level. This decrease is caused by screening of the electrostatic attraction between these particles.

  9. Fish Aggregation Sites in the Florida Keys

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Spawning aggregations are an important event in the life-history of many coral reef fish species. During short time periods (typically during full moons), fish will...

  10. Model of fractal aggregates induced by shear

    Directory of Open Access Journals (Sweden)

    Wan Zhanhong

    2013-01-01

    Full Text Available It is an undoubted fact that particle aggregates from marine, aerosol, and engineering systems have fractal structures. In this study, fractal geometry is used to describe the morphology of irregular aggregates. The mean-field theory is employed to solve coagulation kinetic equation of aggregates. The Taylor-expansion method of moments in conjunction with the self-similar fractal characteristics is used to represent the particulate field. The effect of the target fractal dimensions on zeroth-order moment, second-order moment, and geometric standard deviation of the aggregates is explored. Results show that the developed moment method is an efficient and powerful approach to solving such evolution equations.

  11. AFM-CSLM Microrheology of aggregated emulsions

    NARCIS (Netherlands)

    Filip, D.

    2006-01-01

    The work in this thesis describes the structural and mechanical properties of weakly aggregated emulsion networks at a meso- and microscopic level, achieved by using a simultaneous combination of two experimental techniques: atomic force microscopy and confocal scanning laser microscopy.

  12. GPP Webinar: The Power of Aggregated Purchasing

    Science.gov (United States)

    Green Power Partnership webinar examining the use of an aggregated model for renewable energy purchases which can lead to significant energy, environmental and financial benefits by addressing administrative cost barriers and leveraging the shared purchasi

  13. Concretes with red mud coarse aggregates

    Directory of Open Access Journals (Sweden)

    Dênio Ramam Carvalho de Oliveira

    2012-06-01

    Full Text Available Red mud (RM is a mineral waste, residue of the Bayer process used to obtain alumina from bauxite. While the exploration of rolled pebble damages the environment and is much more controlled by the government, the huge RM disposal areas do not stop increasing and polluting soil, rivers and groundwater sources in Amazon. In this work, the material mixtures used to produce coarse aggregates presented up to 80% of RM, 30% of metakaolin and 30% of active silica as recycled waste. Several tests were carried out to determine the aggregates physical properties and to evaluate the mechanical performance of the concretes with the new aggregates, including hydraulic abrasion strength, and the results were compared to the reference ones, i.e. rolled pebble concretes. Additionally, the sintering process neutralizes any toxic substance as occur in some RM products like tiles and bricks, and these results have encouraged an industrial or semi-industrial production of RM aggregates for concretes.

  14. A cognitive model for aggregating people's rankings

    National Research Council Canada - National Science Library

    Lee, Michael D; Steyvers, Mark; Miller, Brent

    2014-01-01

    .... Applications of the model to 23 data sets, dealing with general knowledge and prediction tasks, show that the model performs well in producing an aggregate ranking that is often close to the ground...

  15. Alkali-aggregate reactivity (AAR) facts book.

    Science.gov (United States)

    2013-03-01

    This document provides detailed information on alkali-aggregate reactivity (AAR). It primarily discusses alkali-silica reaction (ASR), covering the chemistry, symptoms, test methods, prevention, specifications, diagnosis and prognosis, and mitigation...

  16. Erythrocyte deformability and erythrocyte aggregation in preeclampsia

    NARCIS (Netherlands)

    Pepple, D. J.; Hardeman, M. R.; Mullings, A. M.; Reid, H. L.

    2001-01-01

    One of the features of preeclampsia is impaired blood rheology due to altered erythrocyte aggregation and erythrocyte deformability. We investigated these two parameters which affect the viscosity of blood, along with serum and intraerythrocytic magnesium concentrations, immunoglobulin titres and

  17. The route to protein aggregate superstructures

    DEFF Research Database (Denmark)

    Vetri, Valeria; Foderà, Vito

    2015-01-01

    Depending on external conditions, native proteins may change their structure and undergo different association routes leading to a large scale polymorphism of the aggregates. This feature has been widely observed but is not fully understood yet. This review focuses on morphologies, physico...... changes and dominant forces in driving association together with their connection with the final aggregate structure. Eventually, we will discuss future perspectives in this field and we will comment what is, in our opinion, urgently needed....

  18. Aggregate stability in soils cultivated with eucalyptus

    OpenAIRE

    Avanzi,Junior Cesar; Norton,Lloyd Darrell; Silva,Marx Leandro Naves; Curi,Nilton; Oliveira,Anna Hoffmann; Silva,Mayesse Aparecida da

    2011-01-01

    The objective of this work was to evaluate the aggregate stability of tropical soils under eucalyptus plantation and native vegetation, and assess the relationships between aggregate stability and some soil chemical and physical properties. Argisols, Cambisol, Latosols and Plinthosol within three eucalyptus-cultivated regions, in the states of Espírito Santo, Rio Grande do Sul and Minas Gerais, Brazil, were studied. For each region, soils under native vegetation were compared to those under m...

  19. Probability Aggregates in Probability Answer Set Programming

    OpenAIRE

    Saad, Emad

    2013-01-01

    Probability answer set programming is a declarative programming that has been shown effective for representing and reasoning about a variety of probability reasoning tasks. However, the lack of probability aggregates, e.g. {\\em expected values}, in the language of disjunctive hybrid probability logic programs (DHPP) disallows the natural and concise representation of many interesting problems. In this paper, we extend DHPP to allow arbitrary probability aggregates. We introduce two types of p...

  20. Heating Techniques for Asphalt/Aggregate Mixtures.

    Science.gov (United States)

    1979-12-01

    gravel, and rock, as well as materials that require both crushing and screening, such as limestone and granite. In no case may the aggregate particles...the aggregate surfaces and the cementing action of the bitumen. PLANT-MIX HOT-LAID BITUMINOUS SURFACES Hot-mix bituminous concrete is Composed of...well-graded mineral aggre- gates, mineral filler , and bituminous material (AC or tar, depending on the 4 desired mixture). The hot-mix method of

  1. Discover Aggregates Exceptions over Hidden Web Databases

    OpenAIRE

    Suhaim, Saad Bin; Liu, Weimo; Zhang, Nan

    2016-01-01

    Nowadays, many web databases "hidden" behind their restrictive search interfaces (e.g., Amazon, eBay) contain rich and valuable information that is of significant interests to various third parties. Recent studies have demonstrated the possibility of estimating/tracking certain aggregate queries over dynamic hidden web databases. Nonetheless, tracking all possible aggregate query answers to report interesting findings (i.e., exceptions), while still adhering to the stringent query-count limit...

  2. Aggregation of rat neutrophils by nucleotide triphosphates.

    OpenAIRE

    Ford-Hutchinson, A. W.

    1982-01-01

    1 Adenosine 5'-triphosphate (ATP) and uridine 5'-triphosphate (UTP) at concentrations of 3 x 10(-7)M and greater cause a rapid partially reversible aggregation of rat polymorphonuclear leucocytes. 2 Other nucleotide phosphates are much less active at producing aggregation responses; the agonist potencies being UTP greater than ATP greater than guanosine 5'-triphosphate, cytidine 5'-triphosphate, thymidine 5'-triphosphate; ATP greater than adenosine 5'-diphosphate (ADP) greater than adenosine ...

  3. The Controllability of Monetary Aggregates in Pakistan

    OpenAIRE

    Anjum Siddiqui; Ahmad Waheed

    1995-01-01

    The introduction of new financial instruments and the consequent asset substitutability since the advent of financial deregulation in 1991 has been accompanied by volatility of the money multiplier and the monetary aggregates. While money demand studies exist [Khan (1980)), the modelling of the supply side of money and, in general, the impact of financial innovations on money multipliers and monetary aggregates has been largely ignored. In a recent study, Siddiqui and Waheed (1994a) found tha...

  4. Cholesterol impairment contributes to neuroserpin aggregation

    Science.gov (United States)

    Giampietro, Costanza; Lionetti, Maria Chiara; Costantini, Giulio; Mutti, Federico; Zapperi, Stefano; La Porta, Caterina A. M.

    2017-03-01

    Intraneural accumulation of misfolded proteins is a common feature of several neurodegenerative pathologies including Alzheimer’s and Parkinson’s diseases, and Familial Encephalopathy with Neuroserpin Inclusion Bodies (FENIB). FENIB is a rare disease due to a point mutation in neuroserpin which accelerates protein aggregation in the endoplasmic reticulum (ER). Here we show that cholesterol depletion induced either by prolonged exposure to statins or by inhibiting the sterol reg-ulatory binding-element protein (SREBP) pathway also enhances aggregation of neuroserpin proteins. These findings can be explained considering a computational model of protein aggregation under non-equilibrium conditions, where a decrease in the rate of protein clearance improves aggregation. Decreasing cholesterol in cell membranes affects their biophysical properties, including their ability to form the vesicles needed for protein clearance, as we illustrate by a simple mathematical model. Taken together, these results suggest that cholesterol reduction induces neuroserpin aggregation, even in absence of specific neuroserpin mutations. The new mechanism we uncover could be relevant also for other neurodegenerative diseases associated with protein aggregation.

  5. An energy landscape approach to protein aggregation

    Science.gov (United States)

    Buell, Alexander; Knowles, Tuomas

    2012-02-01

    Protein aggregation into ordered fibrillar structures is the hallmark of a class of diseases, the most prominent examples of which are Alzheimer's and Parkinson's disease. Recent results (e.g. Baldwin et al. J. Am. Chem. Soc. 2011) suggest that the aggregated state of a protein is in many cases thermodynamically more stable than the soluble state. Therefore the solubility of proteins in a cellular context appears to be to a large extent under kinetic control. Here, we first present a conceptual framework for the description of protein aggregation ( see AK Buell et al., Phys. Rev. Lett. 2010) that is an extension to the generally accepted energy landscape model for protein folding. Then we apply this model to analyse and interpret a large set of experimental data on the kinetics of protein aggregation, acquired mainly with a novel biosensing approach (see TPJK Knowles et al, Proc. Nat. Acad. Sc. 2007). We show how for example the effect of sequence modifications on the kinetics and thermodynamics of human lysozyme aggregation can be understood and quantified (see AK Buell et al., J. Am. Chem. Soc. 2011). These results have important implications for therapeutic strategies against protein aggregation disorders, in this case lysozyme systemic amyloidosis.

  6. Ash aggregation in explosive volcanic eruptions

    Science.gov (United States)

    Telling, J. W.; Dufek, J.

    2010-12-01

    We present the result of a recent experimental and numerical investigation of ash aggregation in volcanic plumes. Eruption dynamics are sensitive to microphysical processes, like ash aggregation, yet are difficult to parameterize based on dynamics simulations of whole eruption columns due to the lack of sufficient resolution. Here we present the results of experiments that develop a probabilistic relationship for ash aggregation based on particle size, collisional energy and atmospheric water vapor. These relationships can be integrated into large-scale simulations of eruption column behavior in conjunction with a reconstructed velocity distribution of the ash in the column. The physical experiment was carried out in a contained tank designed to allow for the control of atmospheric water vapor. Image data is recorded with a high speed camera and post-processed to determine the number of collisions, energy of collisions and probability of aggregation. We will present the results of aggregation probability and the effects of incorporating these results into a multiphase model of a three-dimensional eruption column, where the effects of ash aggregation are especially important in regions of high shear and high granular temperature.

  7. Paper Sludge Reuse in Lightweight Aggregates Manufacturing.

    Science.gov (United States)

    Chen, How-Ji; Hsueh, Ying-Chih; Peng, Ching-Fang; Tang, Chao-Wei

    2016-10-27

    The lightweight aggregates used by the civil engineering market are sintered at a high temperature, about 1200 °C. In times of high energy prices and regulation of carbon dioxide emissions, lightweight aggregate products of the high-temperature process in sales marketing are not readily accepted. This study developed a sintered-type paper sludge lightweight aggregate. In order to reduce energy consumption, substitution of some reservoir sediment clay in paper sludge substitutes is to be expected. The study used two types of paper sludge (green clay paper sludge and paper pulp sludge). The sintering temperature was reduced effectively as the green clay paper sludge was substituted for some of the reservoir sediment clay, and the optimum substitute ranges of green clay paper sludge were 10%-50%. The optimum substitute ranges of the paper pulp sludge were 10%-40%. Test results show that the properties of aggregates have a particle density of 0.66-1.69 g/cm³, a water absorption of 5%-30%, and a loss on ignition of 10%-43%. The loss on ignition of aggregate became greater with the increase in paper sludge content. This means that the calorific value provided by the paper sludge will increase as paper sludge content increases. Paper sludge can therefore be considered a good material to provide heat energy for sintering lightweight aggregate.

  8. Two-step percolation in aggregating systems

    Directory of Open Access Journals (Sweden)

    N. Lebovka

    2017-03-01

    Full Text Available The two-step percolation behavior in aggregating systems was studied both experimentally and by means of Monte Carlo (MC simulations. In experimental studies, the electrical conductivity, σ, of colloidal suspension of multiwalled carbon nanotubes (CNTs in decane was measured. The suspension was submitted to mechanical de-liquoring in a planar filtration-compression conductometric cell. During de-liquoring, the distance between the measuring electrodes continuously decreased and the CNT volume fraction φ continuously increased (from 10^{-3} up to ≈ 0.3% v/v. The two percolation thresholds at φ_1 ≲ 10^{-3} and φ_2 ≈ 10^{-2} can reflect the interpenetration of loose CNT aggregates and percolation across the compact conducting aggregates, respectively. The MC computational model accounted for the core-shell structure of conducting particles or their aggregates, the tendency of a particle for aggregation, the formation of solvation shells, and the elongated geometry of the conductometric cell. The MC studies revealed two smoothed percolation transitions in σ(φ dependencies that correspond to the percolation through the shells and cores, respectively. The data demonstrated a noticeable impact of particle aggregation on anisotropy in electrical conductivity σ(φ measured along different directions in the conductometric cell.

  9. Structure-based inhibitors of tau aggregation

    Science.gov (United States)

    Seidler, P. M.; Boyer, D. R.; Rodriguez, J. A.; Sawaya, M. R.; Cascio, D.; Murray, K.; Gonen, T.; Eisenberg, D. S.

    2018-02-01

    Aggregated tau protein is associated with over 20 neurological disorders, which include Alzheimer's disease. Previous work has shown that tau's sequence segments VQIINK and VQIVYK drive its aggregation, but inhibitors based on the structure of the VQIVYK segment only partially inhibit full-length tau aggregation and are ineffective at inhibiting seeding by full-length fibrils. Here we show that the VQIINK segment is the more powerful driver of tau aggregation. Two structures of this segment determined by the cryo-electron microscopy method micro-electron diffraction explain its dominant influence on tau aggregation. Of practical significance, the structures lead to the design of inhibitors that not only inhibit tau aggregation but also inhibit the ability of exogenous full-length tau fibrils to seed intracellular tau in HEK293 biosensor cells into amyloid. We also raise the possibility that the two VQIINK structures represent amyloid polymorphs of tau that may account for a subset of prion-like strains of tau.

  10. Effect of metal ratio and calcination temperature of chromium based mixed oxides catalyst on FAME density from palm fatty acid distillate

    Science.gov (United States)

    Wan, Z.; Fatimah, S.; Shahar, S.; Noor, A. C.

    2017-09-01

    Mixed oxides chromium based catalysts were synthesized via sol-gel method for the esterification of palm fatty acid distillate (PFAD) to produce fatty acid methyl ester (FAME). The reactions were conducted in a batch reactor at reaction temperature of 160 °C for 4 h and methanol to PFAD molar ratio of 3:1. The effects of catalyst preparation conditions which are the mixed metal ratio and calcination temperature were studied. The various metal ratio of Cr:Mn (1:0, 0:1, 1:1, 1:2 and 2:1) and Cr:Ti (0:1, 1:1, 1:2 and 2:1) resulted in FAME density ranges from 1.041 g/cm3 to 0.853 g/cm3 and 1.107 g/cm3 to 0.836 g/cm3, respectively. The best condition catalyst was found to be Cr:Ti metal ratio of 1:2 and Cr:Mn metal ratio of 1:1. The calcination temperature of the mixed oxides between 300 °C to 700°C shows effect on the FAME density obtained in the reaction. The calcination at 500°C gave the lowest FAME density of 0.836 g/cm3 and 0.853 g/cm3 for Cr:Ti and Cr:Mn mixed oxides, respectively. The density of FAME is within the value range of the biodiesel fuel property. Thus, mixed oxides of Cr-Ti and Cr-Mn have good potentials as heterogeneous catalyst for FAME synthesis from high acid value oils such as PFAD.

  11. Superb adsorption capacity of hierarchical calcined Ni/Mg/Al layered double hydroxides for Congo red and Cr(VI) ions.

    Science.gov (United States)

    Lei, Chunsheng; Zhu, Xiaofeng; Zhu, Bicheng; Jiang, Chuanjia; Le, Yao; Yu, Jiaguo

    2017-01-05

    The preparation of hierarchical porous materials as catalysts and sorbents has attracted much attention in the field of environmental pollution control. Herein, Ni/Mg/Al layered double hydroxides (NMA-LDHs) hierarchical flower-like hollow microspheres were synthesized by a hydrothermal method. After the NMA-LDHs was calcined at 600°C, NMA-LDHs transformed into Ni/Mg/Al layered double oxides (NMA-LDOs), which maintained the hierarchical flower-like hollow structure. The crystal phase, morphology, and microstructure of the as-prepared samples were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, energy-dispersive X-ray spectroscopy elemental mapping, Fourier transform infrared spectroscopy, and nitrogen adsorption-desorption methods. Both the calcined and non-calcined NMA-LDHs were examined for their performance to remove Congo red (CR) and hexavalent chromium (Cr(VI)) ions in aqueous solution. The maximum monolayer adsorption capacities of CR and Cr(VI) ions over the NMA-LDOs sample were 1250 and 103.4mg/g at 30°C, respectively. Thermodynamic studies indicated that the adsorption process was endothermic in nature. In addition, the addition of coexisting anions negatively influenced the adsorption capacity of Cr(VI) ions, in the following order: CO3(2-)>SO4(2-)>H2PO4(-)>Cl(-). This work will provide new insight into the design and fabrication of advanced adsorption materials for water pollutant removal. Copyright © 2016 Elsevier B.V. All rights reserved.

  12. An aggregation sensing reporter identifies leflunomide and teriflunomide as polyglutamine aggregate inhibitors.

    Science.gov (United States)

    Fuentealba, Rodrigo A; Marasa, Jayne; Diamond, Marc I; Piwnica-Worms, David; Weihl, Conrad C

    2012-02-01

    Intracellular protein aggregation is a common pathologic feature in neurodegenerative diseases such as Huntington' disease, amyotrophic lateral sclerosis and Parkinson' disease. Although progress towards understanding protein aggregation in vitro has been made, little of this knowledge has translated to patient therapy. Moreover, mechanisms controlling aggregate formation and catabolism in cellulo remain poorly understood. One limitation is the lack of tools to quantitatively monitor protein aggregation and disaggregation. Here, we developed a protein-aggregation reporter that uses huntingtin exon 1 containing 72 glutamines fused to the N-terminal end of firefly luciferase (httQ72-Luc). httQ72-Luc fails to aggregate unless seeded by a non-luciferase-containing polyglutamine (polyQ) protein such as Q80-cfp. Upon co-aggregation, httQ72-luc becomes insoluble and loses its enzymatic activity. Using httQ72-Luc with Q80(CFP/YFP) as seeds, we screened the Johns Hopkins Clinical Compound Library and identified leflunomide, a dihydroorotate dehydrogenase inhibitor with immunosuppressive and anti-psoriatic activities, as a novel drug that prevents polyQ aggregation. Leflunomide and its active metabolite teriflunomide inhibited protein aggregation independently of their known role in pyrimidine biosynthesis, since neither uridine treatment nor other pyrimidine biosynthesis inhibitors affected polyQ aggregation. Inducible cell line and cycloheximide-chase experiments indicate that these drugs prevent incorporation of expanded polyQ into an aggregate. This study demonstrates the usefulness of luciferase-based protein aggregate reporters for high-throughput screening applications. As current trials are under-way for teriflunomide in the treatment of multiple sclerosis, we propose that this drug be considered a possible therapeutic agent for polyQ diseases.

  13. Influence of Aggregate Wettability with Different Lithology Aggregates on Concrete Drying Shrinkage

    OpenAIRE

    Yuanchen Guo; Jueshi Qian; Xue Wang; Zhengyi Yan; Huadong Zhong

    2015-01-01

    The correlation of the wettability of different lithology aggregates and the drying shrinkage of concrete materials is studied, and some influential factors such as wettability and wetting angle are analyzed. A mercury porosimeter is used to measure the porosities of different lithology aggregates accurately, and the pore size ranges that significantly affect the drying shrinkage of different lithology aggregate concretes are confirmed. The pore distribution curve of the different coarse aggr...

  14. Highly enhanced photocatalytic reduction of Cr(VI) on AgI/TiO{sub 2} under visible light irradiation: Influence of calcination temperature

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Qi; Shi, Xiaodong; Xu, Jianjia [School of Environmental Science and Engineering, Zhejiang Gongshang University, Hangzhou 310018 (China); Crittenden, John C. [The Brook Byer Institute for Sustainable Systems and School of Civil and Environmental Engineering, Georgia Institute of Technology, Atlanta,GA 30332 (United States); Liu, Enqin; Zhang, Yi [School of Environmental Science and Engineering, Zhejiang Gongshang University, Hangzhou 310018 (China); Cong, Yanqing, E-mail: yqcong@hotmail.com [School of Environmental Science and Engineering, Zhejiang Gongshang University, Hangzhou 310018 (China)

    2016-04-15

    Highlights: • β-AgI riched AgI/TiO2 was obtained after simple heat pretreatment at 350 °C. • Greatly enhanced visible light response was observed on AgI/TiO2-350. • AgI/TiO2-350 exhibited superior photocatalytic activity and stability. • 5 times rate constant for Cr(VI) reduction was achieved. • More efficient separation and easier transfer of e{sup −}–h{sup +} pairs were facilitated. - Abstract: AgI/TiO{sub 2} was prepared using a dissolution-precipitation method, followed by calcination at different temperatures (100–700 °C). The as-prepared AgI/TiO{sub 2} powders were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), ultraviolet-visible diffuse reflectance spectroscopy (UV–Vis-DRS) and electrochemical impedance spectroscopy (EIS). The results revealed that calcination temperature significantly impacted the visible light absorption of AgI/TiO{sub 2} along with a shift from metastable γ-AgI to relatively stable β-AgI. We found that highest photocatalytic reduction rate of Cr(VI) and β-AgI content were obtained for a calcination temperature of 350 °C. Furthermore, the pseudo-first order rate constant was five times that for a photocatalyst calcined at 100 °C. The dramatically enhanced reduction rate of Cr(VI) was attributed to enhanced visible light absorption and greatly reduced charge transfer resistance, which eventually facilitates more efficient separation and easier transfer of photogenerated electron–hole pairs to the catalyst surface. Other experimental conditions were also carefully investigated and optimized with initial AgI loading percentage (5%), catalyst dosage (1.0 g/L), coexisting organics (1.0 mmol/L EDTA) and pH (1–2). The optimal AgI/TiO{sub 2} exhibited good stability with little change in activity after 5 cycles.

  15. Influence of Zn/Fe Molar Ratio on Optical and Magnetic Properties of ZnO and ZnFe2O4 Nanocrystal as Calcined Products of Layered Double Hydroxides

    Directory of Open Access Journals (Sweden)

    Abdullah Ahmed Ali Ahmed

    2014-01-01

    Full Text Available The coprecipitation method has been used to synthesize layered double hydroxide (Zn-Fe-LDH nanostructure at different Zn2+/Fe3+ molar ratios. The structural properties of samples were studied using powder X-ray diffraction (PXRD. LDH samples were calcined at 600°C to produce mixed oxides (ZnO and ZnFe2O4. The crystallite size of mixed oxide was found in the nanometer scale (18.1 nm for ZnFe2O4 and 43.3 nm for ZnO. The photocatalytic activity of the calcination products was investigated using ultraviolet-visible-near infrared (UV-VIS-NIR diffuse reflectance spectroscopy. The magnetic properties of calcined LDHs were investigated using a vibrating sample magnetometer (VSM. The calcined samples showed a paramagnetic behavior for all Zn2+/Fe3+ molar ratios. The effect of molar ratio on magnetic susceptibility of the calcined samples was also studied.

  16. Metaconcrete: Engineered aggregates for enhanced dynamic performance

    Science.gov (United States)

    Mitchell, Stephanie J.

    This work presents the development and investigation of a new type of concrete for the attenuation of waves induced by dynamic excitation. Recent progress in the field of metamaterials science has led to a range of novel composites which display unusual properties when interacting with electromagnetic, acoustic, and elastic waves. A new structural metamaterial with enhanced properties for dynamic loading applications is presented, which is named metaconcrete. In this new composite material the standard stone and gravel aggregates of regular concrete are replaced with spherical engineered inclusions. Each metaconcrete aggregate has a layered structure, consisting of a heavy core and a thin compliant outer coating. This structure allows for resonance at or near the eigenfrequencies of the inclusions, and the aggregates can be tuned so that resonant oscillations will be activated by particular frequencies of an applied dynamic loading. The activation of resonance within the aggregates causes the overall system to exhibit negative effective mass, which leads to attenuation of the applied wave motion. To investigate the behavior of metaconcrete slabs under a variety of different loading conditions a finite element slab model containing a periodic array of aggregates is utilized. The frequency dependent nature of metaconcrete is investigated by considering the transmission of wave energy through a slab, which indicates the presence of large attenuation bands near the resonant frequencies of the aggregates. Applying a blast wave loading to both an elastic slab and a slab model that incorporates the fracture characteristics of the mortar matrix reveals that a significant portion of the supplied energy can be absorbed by aggregates which are activated by the chosen blast wave profile. The transfer of energy from the mortar matrix to the metaconcrete aggregates leads to a significant reduction in the maximum longitudinal stress, greatly improving the ability of the material

  17. Aspects Concerning the Use of Recycled Concrete Aggregates

    Science.gov (United States)

    Robu, I.; Mazilu, C.; Deju, R.

    2016-11-01

    Natural aggregates (gravel and crushed) are essential non-renewable resources which are used for infrastructure works and civil engineering. Using recycled concrete aggregates (RCA) is a matter of high priority in the construction industry worldwide. This paper presents a study on the use of recycled aggregates, from a concrete of specified class, to acquire new cement concrete with different percentages of recycled aggregates.

  18. Soil aggregation under different management systems

    Directory of Open Access Journals (Sweden)

    Cibele Mascioli Rebello Portella

    2012-12-01

    Full Text Available Considering that the soil aggregation reflects the interaction of chemical, physical and biological soil factors, the aim of this study was evaluate alterations in aggregation, in an Oxisol under no-tillage (NT and conventional tillage (CT, since over 20 years, using as reference a native forest soil in natural state. After analysis of the soil profile (cultural profile in areas under forest management, samples were collected from the layers 0-5, 5-10, 10-20 and 20-40 cm, with six repetitions. These samples were analyzed for the aggregate stability index (ASI, mean weighted diameter (MWD, mean geometric diameter (MGD in the classes > 8, 8-4, 4-2, 2-1, 1-0.5, 0.5-0.25, and < 0.25 mm, and for physical properties (soil texture, water dispersible clay (WDC, flocculation index (FI and bulk density (Bd and chemical properties (total organic carbon - COT, total nitrogen - N, exchangeable calcium - Ca2+, and pH. The results indicated that more intense soil preparation (M < NT < PC resulted in a decrease in soil stability, confirmed by all stability indicators analyzed: MWD, MGD, ASI, aggregate class distribution, WDC and FI, indicating the validity of these indicators in aggregation analyses of the studied soil.

  19. The Mechanisms of Aberrant Protein Aggregation

    Science.gov (United States)

    Cohen, Samuel; Vendruscolo, Michele; Dobson, Chris; Knowles, Tuomas

    2012-02-01

    We discuss the development of a kinetic theory for understanding the aberrant loss of solubility of proteins. The failure to maintain protein solubility results often in the assembly of organized linear structures, commonly known as amyloid fibrils, the formation of which is associated with over 50 clinical disorders including Alzheimer's and Parkinson's diseases. A true microscopic understanding of the mechanisms that drive these aggregation processes has proved difficult to achieve. To address this challenge, we apply the methodologies of chemical kinetics to the biomolecular self-assembly pathways related to protein aggregation. We discuss the relevant master equation and analytical approaches to studying it. In particular, we derive the underlying rate laws in closed-form using a self-consistent solution scheme; the solutions that we obtain reveal scaling behaviors that are very generally present in systems of growing linear aggregates, and, moreover, provide a general route through which to relate experimental measurements to mechanistic information. We conclude by outlining a study of the aggregation of the Alzheimer's amyloid-beta peptide. The study identifies the dominant microscopic mechanism of aggregation and reveals previously unidentified therapeutic strategies.

  20. Aggregates in monoclonal antibody manufacturing processes.

    Science.gov (United States)

    Vázquez-Rey, María; Lang, Dietmar A

    2011-07-01

    Monoclonal antibodies have proved to be a highly successful class of therapeutic products. Large-scale manufacturing of pharmaceutical antibodies is a complex activity that requires considerable effort in both process and analytical development. If a therapeutic protein cannot be stabilized adequately, it will lose partially or totally its therapeutic properties or even cause immunogenic reactions thus potentially further endangering the patients' health. The phenomenon of protein aggregation is a common issue that compromises the quality, safety, and efficacy of antibodies and can happen at different steps of the manufacturing process, including fermentation, purification, final formulation, and storage. Aggregate levels in drug substance and final drug product are a key factor when assessing quality attributes of the molecule, since aggregation might impact biological activity of the biopharmaceutical. In this review it is analyzed how aggregates are formed during monoclonal antibody industrial production, why they have to be removed and the manufacturing process steps that are designed to either minimize or remove aggregates in the final product. Copyright © 2011 Wiley Periodicals, Inc.

  1. Moisture-induced aggregation of lyophilized insulin.

    Science.gov (United States)

    Costantino, H R; Langer, R; Klibanov, A M

    1994-01-01

    A critical problem in the storage and delivery of pharmaceutical proteins is aggregation in the solid state induced by elevated temperature and moisture. These conditions are particularly relevant for studies of protein stability during accelerated storage or for proteins loaded in polymeric delivery devices in vivo. In the present investigation, we have found that, when exposed to an environment simulating these conditions, lyophilized insulin undergoes both covalent and noncovalent aggregation. The covalent process has been elucidated to be intermolecular thiol-catalyzed disulfide interchange following beta-elimination of an intact disulfide bridge in the insulin molecule. This process is accelerated by increasing the temperature and water content of the insulin powder or by performing lyophilization and/or dissolution of insulin in alkaline media. The aggregation can be ameliorated by the presence of Cu2+, which presumably catalyzes the oxidization of free thiols. The water sorption isotherm for insulin reveals that the extent of aggregation directly correlates with the water uptake by the lyophilized insulin powder, thus pointing to the critical role of protein conformational mobility in the aggregation process.

  2. Spectroscopic properties of MgAl{sub 2−x}O{sub 4}:xCr{sup 3+} nanoparticles prepared by a high-temperature calcination method

    Energy Technology Data Exchange (ETDEWEB)

    Du, Xinhua [College of Chemistry, Chemical Engineering and Materials Science, Soochow University, Suzhou 215123 (China); State Key Laboratory of Metastable Materials Science and Technology, Yanshan University, Qinhuangdao 066004 (China); Tian, Hai [Science and Technology on Vacuum Technology and Physics Laboratory, Lanzhou 730000, Gansu (China); Yao, Shiyue [State Key Laboratory of Metastable Materials Science and Technology, Yanshan University, Qinhuangdao 066004 (China); Long, Yumei [College of Chemistry, Chemical Engineering and Materials Science, Soochow University, Suzhou 215123 (China); Liang, Bo, E-mail: liangbo@ysu.edu.cn [State Key Laboratory of Metastable Materials Science and Technology, Yanshan University, Qinhuangdao 066004 (China); Li, Weifeng, E-mail: liweifeng@suda.edu.cn [State Key Laboratory of Metastable Materials Science and Technology, Yanshan University, Qinhuangdao 066004 (China)

    2015-12-01

    In this study, Cr{sup 3+}-doped MgAl{sub 2}O{sub 4} nanophosphors have been prepared via a facile high-temperature calcination route. The structure and morphology of the products were characterized by x-ray diffraction (XRD), scanning electron microscope (SEM) and transmission electron microscopy (TEM) techniques, which confirmed the typical spinel MgAl{sub 2}O{sub 4} phase and sphere-like shape with particle size distribution of 50–80 nm. It was found that the Cr{sup 3+}-doped MgAl{sub 2}O{sub 4} can be efficiently excited by visible light and exhibits intense red emission peaking at 695 nm, corresponding to the {sup 2}E{sub g}→{sup 4}A{sub 2g} transition of Cr{sup 3+} ions. The evolution of the luminescent properties on the Cr-doping concentration (0, 0.5, 1, 2, 3, 4 and 6 mol%) was then investigated and the optimal concentration was 3.0 mol%. It is believed that active intermediates and gases created in the calcining process play important roles not only on the formation of the monodispersed nanoparticles, but also on the homogeneous doping of Cr{sup 3+} at high concentration.

  3. SOx removal by calcined MgAlFe hydrotalcite-like materials: effect of the chemical composition and the cerium incorporation method.

    Science.gov (United States)

    Cantú, Manuel; López-Salinas, Esteban; Valente, Jaime S; Montiel, Ramon

    2005-12-15

    Sulfur oxides are one of the most hazardous atmospheric pollutants since they contribute directly to acid rain formation. Consequently, stringent environmental regulations limit atmospheric SOx emissions, motivating research on efficient ways to reduce them. To supply an alternative to reduce these emissions in fluid catalytic cracking units, this study discloses efficient SOx reducing materials based on calcined MgAlFe hydrotalcite-like compounds (HT's). Thus, HT materials were synthesized by several methods including cerium addition. The adsorption of SO2 was carried out by contacting the calcined solid with a mixture of SO2 (1%) in air at 650 degrees C. It was demonstrated that the isomorphic incorporation of iron increased its reduction capability which was reflected in higher reduction rates and metal sulfate reduction grade at 550 degrees C. Moreover, when cerium was present in the iron-containing materials the saturation rate was improved, because cerium oxide promotes the oxidation of SO2 to SO3. The way cerium is incorporated influences the SO2 adsorption capacity.

  4. Effect of calcination temperature on the activity of solid Ca/Al composite oxide-based alkaline catalyst for biodiesel production.

    Science.gov (United States)

    Meng, Yong-Lu; Wang, Bo-Yang; Li, Shu-Fen; Tian, Song-Jiang; Zhang, Min-Hua

    2013-01-01

    A solid Ca/Al composite oxide-based alkaline catalyst containing Ca(12)Al(14)O(33) and CaO was prepared by chemical synthesis and thermal activation from sodium aluminate solution and calcium hydroxide emulsion. The effect of calcination temperatures ranging from 120 °C to 1000 °C on activity of the catalyst was investigated. The catalyst calcined at 600 °C showed the highest activity with >94% yield of fatty acid methyl esters (i.e. biodiesel) when applied to the transesterification of rapeseed oil at a methanol:oil molar ratio of 15:1 at 65 °C for 3h. Structure and properties of the catalyst were studied and the characterizations with XRD, TGA, FTIR, BET, and SEM demonstrated that the performance of the catalyst was closely related to its specific surface area and crystalline structure. In particular, the generation of crystalline Ca(12)Al(14)O(33) improved the catalytic activity due its synergistic effect with CaO. Copyright © 2012 Elsevier Ltd. All rights reserved.

  5. Fabrication of TiO2 nanorods/nanosheets photoelectrode on Ti mesh by hydrothermal method for degradation of methylene blue:influence of calcination temperature

    Science.gov (United States)

    Deng, Xiaoyong; Ma, Qiuling; Cui, Yuqi; Cheng, Xiuwen; Cheng, Qingfeng

    2017-10-01

    In the study, Using the strategy of hydrothermal reaction followed by annealing at different temperatures, TiO2 nanorods/nanosheets (NRs/NSs) photoelectrodes with diverse microcosmic morphologies and crystal structures were successfully fabricated. Moreover, all samples were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscope (SEM) and Ultraviolet-visible diffuse reflectance spectroscopy (UV-vis DRS). Meanwhile the photoelectrochemical (PECH) properties were recorded through open circuit potential (OCP) and electrochemical impedance spectroscopy (EIS) curves. The photocatalytic (PC) activity of TiO2 NRs/NSs photoelectrodes were further measured by methylene blue (MB) degradation. Results suggest that the nanosheets possessed the width and thickness in the range of 100-400 and 10-20 nm, and the nanorods possessed the diameter in the range of around 10-20 nm, respectively. Also, the TiO2 NRs/NSs photoelectrode calcined at 500 °C exhibited the best proportion of both nanosheets and nanorods and higher photocatalytic activity (73.56%) than those of other TiO2 NRs/NSs photoelectrodes within 150 min under visible light illumination, which was ascribed to higher photoproduction electrons-holes (e/h+) pairs separation and visible light absorption. Therefore, the calcination temperature plays a significant role in altering the morphology and crystal structure of TiO2 NRs/NSs photoelectrode, and then enhanced PC performance.

  6. The Synergistic Effect of Nitrogen Dopant and Calcination Temperature on the Visible-Light-Induced Photoactivity of N-Doped TiO2

    Directory of Open Access Journals (Sweden)

    Yao-Tung Lin

    2013-01-01

    Full Text Available The synergistic effect of nitrogen content and calcinations temperature on the N-doped TiO2 catalysts prepared by sol-gel method was investigated. The phase and structure, chemical state, optical properties, and surface area/pore distribution of N-doped TiO2 were characterized using X-ray diffraction spectrometer, high-resolution transmission electron microscope, X-ray photoelectron spectroscopy, UV-vis diffusion reflectance spectroscopy, and Brunauer-Emmett-Teller specific surface area. Finding showed that the photocatalytic activity of N-doped TiO2 was greatly enhanced compared to pure TiO2 under visible irradiation. N dopants could retard the transformation from anatase to rutile phase. Namely, N-doping effect is attributed to the anatase phase stabilization. The results showed nitrogen atoms were incorporated into the interstitial positions of the TiO2 lattice. Ethylene was used to evaluate the photocatalytic activity of samples under visible-light illumination. The results suggested good anatase crystallization, smaller particle size, and larger surface are beneficial for photocatalytic activity of N-doped TiO2. The N-doped TiO2 catalyst prepared with ammonia to titanium isopropoxide molar ratio of 2.0 and calcinated at 400°C showed the best photocatalytic ability.

  7. One-pot synthesis of carbon supported calcined-Mg/Al layered double hydroxides for antibiotic removal by slow pyrolysis of biomass waste

    Science.gov (United States)

    Tan, Xiaofei; Liu, Shaobo; Liu, Yunguo; Gu, Yanling; Zeng, Guangming; Cai, Xiaoxi; Yan, Zhili; Yang, Chunping; Hu, Xinjiang; Chen, Bo

    2016-12-01

    A biochar supported calcined-Mg/Al layered double hydroxides composite (CLDHs/BC) was synthesized by a one-pot slow pyrolysis of LDHs preloaded bagasse biomass. Multiple characterizations of the product illustrated that the calcined-Mg/Al layered double hydroxides (CLDHs) were successfully coated onto the biochar in slow pyrolysis of pre-treated biomass. The as-synthesized CLDHs/BC could efficiently remove antibiotic tetracycline from aqueous solutions. The coating of CLDHs significantly increased the adsorption ability of biochar, and CLDHs/BC exhibited more than 2 times higher adsorption capacity than that of the pristine biochar (BC) in the tested pH range. The maximum adsorption capacity of CLDHs/BC for tetracycline was 1118.12 mg/g at 318 K. The experimental results suggested that the interaction with LDHs on biochar played a dominant role in tetracycline adsorption, accompanied with π-π interaction and hydrogen bond. This study provides a feasible and simple approach for the preparation of high-performance material for antibiotics contaminated wastewater treatment in a cost-effective way.

  8. Morphological Changes of Limestone Sorbent Particles during Carbonation/Calcination Looping Cycles in a Thermogravimetric Analyzer (TGA) and Reactivation with Steam

    KAUST Repository

    Wu, Y.

    2010-04-15

    Carbonation and calcination looping cycles were carried out on four limestones in a thermogravimetric analyzer (TGA). The CO2 carrying capacity of a limestone particle decays very quickly in the first 10 cycles, reducing to about 20% of its original uptake capacity after 10 cycles for the four limestones studied in this work, and it decreases further to 6-12% after 50 cycles. A new steam reactivation method was applied on the spent sorbent to recover the loss of reactivity. The steam reactivation of multi-cycled samples was conducted at atmospheric pressure. Steam reactivation for 5 min at 130 °C of particles that had undergone 10 cycles resulted in an immediate increase (by 45-60% points) in carrying capacity. The morphological changes of limestone particles during the cycling and steam reactivation were studied using both an optical microscope and scanning electron microscopy (SEM). The diameters of limestone particles shrank by about 2-7% after 10 carbonation/calcination cycles, and the particle diameters swelled significantly (12-22% increase) after steam reactivation. These size changes are important for studies of attrition and mathematical modeling of carbonation. © 2010 American Chemical Society.

  9. Soil aggregation and aggregating agents as affected by long term contrasting management of an Anthrosol.

    Science.gov (United States)

    Zhang, Shulan; Wang, Renjie; Yang, Xueyun; Sun, Benhua; Li, Qinghui

    2016-12-13

    Soil aggregation was studied in a 21-year experiment conducted on an Anthrosol. The soil management regimes consisted of cropland abandonment, bare fallow without vegetation and cropping system. The cropping system was combined with the following nutrient management treatments: control (CONTROL, no nutrient input); nitrogen, phosphorus and potassium (NPK); straw plus NPK (SNPK); and manure (M) plus NPK (MNPK). Compared with the CONTROL treatment, the abandonment treatment significantly increased the formation of large soil macroaggregates (>2 mm) and consequently improved the stability of aggregates in the surface soil layer due to enhancement of hyphal length and of soil organic matter content. However, in response to long-term bare fallow treatment aggregate stability was low, as were the levels of aggregating agents. Long term fertilization significantly redistributed macroaggregates; this could be mainly ascribed to soil organic matter contributing to the formation of 0.5-2 mm classes of aggregates and a decrease in the formation of the >2 mm class of aggregates, especially in the MNPK treatment. Overall, hyphae represented a major aggregating agent in both of the systems tested, while soil organic compounds played significantly different roles in stabilizing aggregates in Anthrosol when the cropping system and the soil management regimes were compared.

  10. Aggregation and Breakup of Colloidal Particle Aggregates in Shear Flow, Studied with Video Microscopy

    NARCIS (Netherlands)

    Tolpekin, V.A.; Duits, Michael H.G.; van den Ende, Henricus T.M.; Mellema, J.

    2004-01-01

    We used video microscopy to study the behavior of aggregating suspensions in shear flow. Suspensions consisted of 920 nm diameter silica spheres, dispersed in a methanol/bromoform solvent, to which poly(ethylene glycol) (M = 35.000 g) was added to effect weak particle aggregation. With our solvent

  11. Soil aggregation and aggregating agents as affected by long term contrasting management of an Anthrosol

    Science.gov (United States)

    Zhang, Shulan; Wang, Renjie; Yang, Xueyun; Sun, Benhua; Li, Qinghui

    2016-12-01

    Soil aggregation was studied in a 21-year experiment conducted on an Anthrosol. The soil management regimes consisted of cropland abandonment, bare fallow without vegetation and cropping system. The cropping system was combined with the following nutrient management treatments: control (CONTROL, no nutrient input); nitrogen, phosphorus and potassium (NPK); straw plus NPK (SNPK); and manure (M) plus NPK (MNPK). Compared with the CONTROL treatment, the abandonment treatment significantly increased the formation of large soil macroaggregates (>2 mm) and consequently improved the stability of aggregates in the surface soil layer due to enhancement of hyphal length and of soil organic matter content. However, in response to long-term bare fallow treatment aggregate stability was low, as were the levels of aggregating agents. Long term fertilization significantly redistributed macroaggregates; this could be mainly ascribed to soil organic matter contributing to the formation of 0.5-2 mm classes of aggregates and a decrease in the formation of the >2 mm class of aggregates, especially in the MNPK treatment. Overall, hyphae represented a major aggregating agent in both of the systems tested, while soil organic compounds played significantly different roles in stabilizing aggregates in Anthrosol when the cropping system and the soil management regimes were compared.

  12. SENSOR indicator framework, and methods for aggregation/dis-aggregation - a guideline

    DEFF Research Database (Denmark)

    Frederiksen, P.; Kristensen, P.; Briquel, V.

    This report collects three guideline contributions to Sensor: the development and proposal of an indicator framework for sustainability impact assessment and criteria for indicator selection, an assessment of international indicator sets for identification of potential indicators for SENSOR impact...... issues, and a description of problems and methodologies for aggregation and dis-aggregation of data and indicators....

  13. Oil-Price Shocks: Beyond Standard Aggregate Demand/Aggregate Supply Analysis.

    Science.gov (United States)

    Elwood, S. Kirk

    2001-01-01

    Explores the problems of portraying oil-price shocks using the aggregate demand/aggregate supply model. Presents a simple modification of the model that differentiates between production and absorption of goods, which enables it to better reflect the effects of oil-price shocks on open economies. (RLH)

  14. Tetranuclear zinc(II-oxy (benzothiazole-2-thiolate aggregate and copper(I phenylthiolate aggregate

    Directory of Open Access Journals (Sweden)

    Abir Goswami

    2015-12-01

    Full Text Available A tetranuclear zinc-oxy (benzothiazole-2-thiolate aggregate whose structure has a C3-axis passing through ZnO unit relating three other zinc ions and a tetranuclear copper(I phenylthiolate aggregate having each thiphenolate ligand bridging three copper ions are reported. These aggregates were prepared by hydrothermal reactions of 2,2′-dithiobis-(benzothiazole with zinc nitrate or copper(I iodide, respectively. The reaction of zinc nitrate passed through in situ abstraction of a oxy ligand from moisture to form a Zn4O core holding six 2-benzothiazolethiolate ligands, and during the formation of the aggregate, cleavage of S–S bond of 2,2′-dithiobis-(benzothiazole took place. Whereas, an aggregate formed by self-assembling of copper(I phenylthiolate was formed after extensive degradation of 2,2′-dithiobis-(benzothiazole during solvothermal reaction.

  15. Organic carbon, water repellency and soil stability to slaking at aggregate and intra-aggregate scales

    Science.gov (United States)

    Jordán López, Antonio; García-Moreno, Jorge; Gordillo-Rivero, Ángel J.; Zavala, Lorena M.; Cerdà, Artemi; Alanís, Nancy; Jiménez-Compán, Elizabeth

    2015-04-01

    Water repellency (WR) is a property of some soils that inhibits or delays water infiltration between a few seconds and days or weeks. Inhibited or delayed infiltration contributes to ponding and increases runoff flow generation, often increasing soil erosion risk. In water-repellent soils, water infiltrates preferentially through cracks or macropores, causing irregular soil wetting patterns, the development of preferential flow paths and accelerated leaching of nutrients. Although low inputs of hydrophobic organic substances and high mineralization rates lead to low degrees of WR in cropped soils, it has been reported that conservative agricultural practices may induce soil WR. Although there are many studies at catchment, slope or plot scales very few studies have been carried out at particle or aggregate scale. Intra-aggregate heterogeneity of physical, biological and chemical properties conditions the transport of substances, microbial activity and biochemical processes, including changes in the amount, distribution and chemical properties of organic matter. Some authors have reported positive relationships between soil WR and aggregate stability, since it may delay the entry of water into aggregates, increase structural stability and contribute to reduce soil erosion risk. Organic C (OC) content, aggregate stability and WR are therefore strongly related parameters. In the case of agricultural soils, where both the type of management as crops can influence all these parameters, it is important to evaluate the interactions among them and their consequences. Studies focused on the intra-aggregate distribution of OC and WR are necessary to shed light on the soil processes at a detailed scale. It is extremely important to understand how the spatial distribution of OC in soil aggregates can protect against rapid water entry and help stabilize larger structural units or lead to preferential flow. The objectives of this research are to study [i] the OC content and the

  16. Inflammation Induces TDP-43 Mislocalization and Aggregation.

    Directory of Open Access Journals (Sweden)

    Ana Sofia Correia

    Full Text Available TAR DNA-binding protein 43 (TDP-43 is a major component in aggregates of ubiquitinated proteins in amyotrophic lateral sclerosis (ALS and frontotemporal lobar degeneration (FTLD. Here we report that lipopolysaccharide (LPS-induced inflammation can promote TDP-43 mislocalization and aggregation. In culture, microglia and astrocytes exhibited TDP-43 mislocalization after exposure to LPS. Likewise, treatment of the motoneuron-like NSC-34 cells with TNF-alpha (TNF-α increased the cytoplasmic levels of TDP-43. In addition, the chronic intraperitoneal injection of LPS at a dose of 1mg/kg in TDP-43(A315T transgenic mice exacerbated the pathological TDP-43 accumulation in the cytoplasm of spinal motor neurons and it enhanced the levels of TDP-43 aggregation. These results suggest that inflammation may contribute to development or exacerbation of TDP-43 proteinopathies in neurodegenerative disorders.

  17. Principles of Need and the Aggregation Thesis.

    Science.gov (United States)

    Gustavsson, Erik; Juth, Niklas

    2017-09-02

    Principles of need are constantly referred to in health care priority setting. The common denominator for any principle of need is that it will ascribe some kind of special normative weight to people being worse off. However, this common ground does not answer the question how a plausible principle of need should relate to the aggregation of benefits across individuals. Principles of need are sometimes stated as being incompatible with aggregation and sometimes characterized as accepting aggregation in much the same way as utilitarians do. In this paper we argue that if one wants to take principles of need seriously both of these positions have unreasonable implications. We then characterize and defend a principle of need consisting of sufficientarian elements as well as prioritarian which avoids these unreasonable implications.

  18. Relationship between macroeconomic aggregates and bank performance

    Directory of Open Access Journals (Sweden)

    Mitrović Ranka

    2016-01-01

    Full Text Available The aim of the paper is relations between some macroeconomic aggregates and performance of banks. This paper show analysis of trends in gross domestic product, exchange rates, interest rates, inflation load, developments in the balance of payments. On the business side, performance is achieved insight into the liquidity, capital adequacy, and the amount of non-performable loans. The aim of the research is to refute or confirm the interconnectedness of movement values of macroeconomic aggregates and bank performance. The analysis confirmed the association of two set variables. The negative value movements of macroeconomic aggregates directly or indirectly have an impact on the quality of performance of the banking sector. Therefore, it is necessary to define an adequate strategy of the economy, would not it safer to carry out the process of adapting to new developments in the market, such as the global financial crisis, the rise in unproductive enterprises, distrust customers etc.

  19. Aggregation of organic matter by pelagic tunicates

    Energy Technology Data Exchange (ETDEWEB)

    Pomeroy, L.R. (Univ. of Georgia, Athens); Deibel, D.

    1980-07-01

    Three genera of pelagic tunicates were fed concentrates of natural seston and an axenic diatom culture. Fresh and up to 4-day-old feces resemble flocculent organic aggregates containing populations of microorganisms, as described from highly productive parts of the ocean, and older feces resemble the nearly sterile flocculent aggregates which are ubiquitous in surface waters. Fresh feces consist of partially digested phytoplankton and other inclusions in an amorphous gelatinous matrix. After 18 to 36 h, a population of large bacteria develops in the matrix and in some of the remains of phytoplankton contained in the feces. From 48 to 96 h, protozoan populations arise which consume the bacteria and sometimes the remains of the phytoplankton in the feces. Thereafter only a sparse population of microorganisms remains, and the particles begin to fragment. Water samples taken in or below dense populations of salps and doliolids contained greater numbers of flocculent aggregates than did samples from adjacent stations.

  20. Multi-Dimensional Aggregation for Temporal Data

    DEFF Research Database (Denmark)

    Böhlen, M. H.; Gamper, J.; Jensen, Christian Søndergaard

    2006-01-01

    Business Intelligence solutions, encompassing technologies such as multi-dimensional data modeling and aggregate query processing, are being applied increasingly to non-traditional data. This paper extends multi-dimensional aggregation to apply to data with associated interval values that capture...... when the data hold. In temporal databases, intervals typically capture the states of reality that the data apply to, or capture when the data are, or were, part of the current database state. This paper proposes a new aggregation operator that addresses several challenges posed by interval data. First......, the intervals to be associated with the result tuples may not be known in advance, but depend on the actual data. Such unknown intervals are accommodated by allowing result groups that are specified only partially. Second, the operator contends with the case where an interval associated with data expresses...

  1. Aggregation kinetics and structure of cryoimmunoglobulins clusters

    CERN Document Server

    De Spirito, M; Bassi, F A; Di Stasio, E; Giardina, B; Arcovito, G

    2002-01-01

    Cryoimmunoglobulins are pathological antibodies characterized by a temperature-dependent reversible insolubility. Rheumatoid factors (RF) are immunoglobulins possessing anti-immunoglobulin activity and usually consist of an IgM antibody that recognizes IgG as antigen. These proteins are present in sera of patients affected by a large variety of different pathologies, such as HCV infection, neoplastic and autoimmune diseases. Aggregation and precipitation of cryoimmunoglobulins, leading to vasculiti, are physical phenomena behind such pathologies. A deep knowledge of the physico-chemical mechanisms regulating such phenomena plays a fundamental role in biological and clinical applications. In this work, a preliminary investigation of the aggregation kinetics and of the final macro- molecular structure of the aggregates is presented. Through static light scattering techniques, the gyration radius R/sub g/ and the fractal dimension D/sub m/ of the growing clusters have been determined. However, while the initial ...

  2. An Aß concatemer with altered aggregation propensities

    DEFF Research Database (Denmark)

    Giehm, L; Dal Degan, F; Fraser, P

    2010-01-01

    We present an analysis of the conformational and aggregative properties of an A beta concatemer (Con-Alz) of interest for vaccine development against Alzheimer's disease. Con-Alz consists of 3 copies of the 43 residues of the A beta peptide separated by the P2 and P30 T-cell epitopes from......, but it is unable to assemble into classical amyloid fibrils. Despite its high propensity to aggregate, Con-Alz does not show any significant ability to permeabilize vesicles, which for fibrillating proteins is taken to be a key factor in aggregate cytotoxicity and is attributed to oligomers formed at an early...... stage in the fibrillation process. Physically linking multiple copies of the A beta-peptide may thus sterically restrict Con-Alz against forming cytotoxic oligomers, forcing it instead to adopt a less well-organized assembly of intermeshed polypeptide chains. (C) 2010 Elsevier B.V. All rights reserved....

  3. Wind energy aggregation: A coalitional game approach

    KAUST Repository

    Baeyens, E.

    2011-12-01

    In this paper we explore the extent to which a group of N wind power producers can exploit the statistical benefits of aggregation and quantity risk sharing by forming a willing coalition to pool their variable power to jointly offer their aggregate power output as single entity into a forward energy market. We prove that wind power generators will always improve their expected profit when they aggregate their generated power and use tools from coalitional game theory to design fair sharing mechanisms to allocate the payoff among the coalition participants. We show that the corresponding coalitional game is super-additive and has a nonempty core. Hence, there always exists a mechanism for profit-sharing that makes the coalition stable. However, the game is not convex and the celebrated Shapley value may not belong to the core of the game. An allocation mechanism that minimizes the worst-case dissatisfaction is proposed. © 2011 IEEE.

  4. Assays for alpha-synuclein aggregation

    DEFF Research Database (Denmark)

    Giehm, Lise; Lorenzen, Nikolai; Otzen, Daniel

    2011-01-01

    Over the last few decades, protein aggregation gone from being an irritating side product in the test tube to becoming a subject of great interest. This has been stimulated by the realization that a large and growing number of diseases is associated with the formation and accumulation of proteins...... aggregates 1. The ability to form amyloid structures has also been exploited by living systems, where proteins forming fibrils during the normal life-cycle have functional rather than disease associated properties 2; 3; 4; 5. Thus, understanding the structural features of fibrils, as well as the processes...... leading to their formation is important for designing new drugs as well as in development of new nano-biomaterials such as nano-tubes, wires, scaffolds etc. 6. Understanding the process of amyloid formation requires an ability to reproduce this aggregation under controlled circumstances, in other words...

  5. Combined research effort on aggregate road materials

    Science.gov (United States)

    Kuznetsova, Elena; Hoff, Inge; Willy Danielsen, Svein; Wigum, Børge Johannes; Fladvad, Marit; Rieksts, Karlis; Loranger, Benoit; Barbieri, Diego

    2017-04-01

    In European countries, the average aggregate consumption per capita is 5 tons per year (European Aggregates Association 2016), while the corresponding number in Norway is 11 tons (Neeb 2015). Due to the increased demand for sand and gravel for construction purposes, e.g. in road construction, the last decade has seen a significant trend towards the use of crushed rock aggregates. Neeb (2015) reports that half of the Norwegian aggregate production (sand, gravel and crushed rock) is used for road construction, and 33 % of the overall sold tonnage of crushed rock is exported. This resource has been more and more preferred over sand and gravel due to the significant technological development of its process and utilization phase. In Norway, the development and implementation of crushed aggregate technology has been the main approach to solve natural resource scarcity (Danielsen and Kuznetsova 2015). In order to reduce aggregates transportation, it is aimed to use local aggregates and aggregates processed from rock excavations, tunneling, road cuts, etc. One issue focused in this research is the influence from blasting and processing on the final quality of the crushed aggregates, specifically relating to the properties for road construction purposes. It is therefor crucial to plan utilization of available materials for use in different road layers following the same production line. New developments and improved availability of mobile crushing and screening equipment could produce more sustainable and profitable sources of good quality aggregate materials from small volume deposits in proximity to construction sites. One of the biggest challenges today to use these materials is that the pavement design manual sets rigid requirements for pavement layers. Four research projects are being conducted in Norway to improve the use of local materials for road construction. Four aspects are to be covered by the research: a) geological characteristics of the materials, their b

  6. Recycled aggregates in concrete production: engineering properties and environmental impact

    OpenAIRE

    Seddik Meddah Mohammed

    2017-01-01

    Recycled concrete aggregate is considered as the most abundant and used secondary aggregate in concrete production, other types of solid waste are also being used in concrete for specific purposes and to achieve some desired properties. Recycled aggregates and particularly, recycled concrete aggregate substantially affect the properties and mix design of concrete both at fresh and hardened states since it is known by high porosity due to the adhered layer of old mortar on the aggregate which ...

  7. 200 North Aggregate Area source AAMS report

    Energy Technology Data Exchange (ETDEWEB)

    1993-06-01

    This report presents the results of an aggregate area management study (AAMS) for the 200 North Aggregate Area in the 200 Areas of the US Department of Energy (DOE) Hanford Site in Washington State. This scoping level study provides the basis for initiating Remedial Investigation/Feasibility Study (RI/FS) activities under the Comprehensive Environmental Response, Compensation, and Liability Act of 1980 (CERCLA) or Resource Conservation and Recovery Act (RCRA) Facility Investigations (RFI) and Corrective Measures Studies (CMS) under RCRA. This report also integrates select RCRA treatment, storage, or disposal (TSD) closure activities with CERCLA and RCRA past practice investigations.

  8. Location Aggregation of Spatial Population CTMC Models

    Directory of Open Access Journals (Sweden)

    Luca Bortolussi

    2016-10-01

    Full Text Available In this paper we focus on spatial Markov population models, describing the stochastic evolution of populations of agents, explicitly modelling their spatial distribution, representing space as a discrete, finite graph. More specifically, we present a heuristic approach to aggregating spatial locations, which is designed to preserve the dynamical behaviour of the model whilst reducing the computational cost of analysis. Our approach combines stochastic approximation ideas (moment closure, linear noise, with computational statistics (spectral clustering to obtain an efficient aggregation, which is experimentally shown to be reasonably accurate on two case studies: an instance of epidemic spreading and a London bike sharing scenario.

  9. Relative aggregation operator in database fuzzy querying

    Directory of Open Access Journals (Sweden)

    Luminita DUMITRIU

    2005-12-01

    Full Text Available Fuzzy selection criteria querying relational databases include vague terms; they usually refer linguistic values form the attribute linguistic domains, defined as fuzzy sets. Generally, when a vague query is processed, the definitions of vague terms must already exist in a knowledge base. But there are also cases when vague terms must be dynamically defined, when a particular operation is used to aggregate simple criteria in a complex selection. The paper presents a new aggregation operator and the corresponding algorithm to evaluate the fuzzy query.

  10. Effective aggregating of tractors for transportation

    Directory of Open Access Journals (Sweden)

    Petar DIMITROV

    2012-01-01

    Full Text Available The paper discusses the importance of tractors for the technological and transportation activities in agriculture. It also presents a methodological approach and an algorithm based on the criteria for the full utilization of the tractors’ gravity and power for the successful aggregating of tractors when performing these activities. The offered mathematical model makes it possible to determine the sphere of full aggregation of tractors in transport within the broad range of change of the production conditions’ indicators with the help of board computers.

  11. Influence of Aggregate Wettability with Different Lithology Aggregates on Concrete Drying Shrinkage

    Directory of Open Access Journals (Sweden)

    Yuanchen Guo

    2015-01-01

    Full Text Available The correlation of the wettability of different lithology aggregates and the drying shrinkage of concrete materials is studied, and some influential factors such as wettability and wetting angle are analyzed. A mercury porosimeter is used to measure the porosities of different lithology aggregates accurately, and the pore size ranges that significantly affect the drying shrinkage of different lithology aggregate concretes are confirmed. The pore distribution curve of the different coarse aggregates is also measured through a statistical method, and the contact angle of different coarse aggregates and concrete is calculated according to the linear fitting relationship. Research shows that concrete strength is determined by aggregate strength. Aggregate wettability is not directly correlated with concrete strength, but wettability significantly affects concrete drying shrinkage. In all types’ pores, the greatest impacts on wettability are capillary pores and gel pores, especially for the pores of the size locating 2.5–50 nm and 50–100 nm two ranges.

  12. Calculation of percent shrinkage in human fetal diaphyseal lengths from fresh bone to carbonized and calcined bone using Petersohn and Köhler's data.

    Science.gov (United States)

    Huxley, A K; Kósa, F

    1999-05-01

    Calculation of age from fetal and newborn remains may be problematic, and when these remains are altered by maceration, decomposition or burning, age may be more difficult to discern. When soft tissue indicators are transformed, then two techniques exist for accurate age determination; dental development, which may prove difficult given the degree of tissue alteration; and appearance, size and fusion of ossification centers, including diaphyseal length, which may yield inaccurate ages if shrinkage is not accounted for. This study is undertaken to facilitate age calculation by systematically re-evaluating diaphyseal shrinkage and determine shrinkage rates from wet to carbonized states and wet to calcined states using Petersohn and Köhler's data, originally published in German and then published in Fazekas and Kósa (1978:362-369). Average shrinkage, standard deviation, minimum and maximum values are calculated for each diaphysis and then for all diaphyses between 4-10 lunar months (LM) and for newborns. Associated values for carbonized diaphyses are: 4 LM--32.50% +/- 12.12%; 5 LM--14.04% +/- 4.44%; 6 LM--6.78% +/- 1.06%; 7 LM--4.18% +/- 0.31%; 8 LM--3.47% +/- 0.42%; 9 LM--3.05% +/- 0.18%; 10 LM--2.46% +/- 0.67%; and in newborns 2.16% +/- 0.29%. Similar values for calcined diaphyses are: 4 LM--40.11% +/- 17.51%; 5 LM--18.29% +/- 4.42%; 6 LM--9.84% +/- 1.27%; 7 LM--9.82% +/- 0.51%; 8 LM--9.42% +/- 0.72%; 9 LM--9.45% +/- 0.33%; 10 LM--8.94% +/- 0.37%; and in newborns 8.96% +/- 0.49%. These findings suggest that percent shrinkage due to carbonization and calcination is greatest in the earliest age groups, decreasing substantially with advancing age. The rates of shrinkage, however, vary by the burning process utilized and age group studied. These general findings are similar to those of Petersohn and Köhler, yet specific values for percent shrinkage vary greatly from values cited in this analysis. These data provide a means to assess the degree of shrinkage that

  13. Effects of calcining temperature on photocatalysis of g-C{sub 3}N{sub 4}/TiO{sub 2} composites for hydrogen evolution from water

    Energy Technology Data Exchange (ETDEWEB)

    Qu, Ailan, E-mail: elainqal@163.com; Xu, Xinmei; Xie, Haolong; Zhang, Yangyu; Li, Yuyu; Wang, Junxian

    2016-08-15

    Highlights: • TiO{sub 2} promotes melon to form at 400 °C, whereas it forms at 500 °C for only melamine. • The highest photocatalytic activity was achieved when calcination was performed at 400 °C. • Coordinated N−Ti−N bonds were formed in MA/TiO{sub 2} (400) and disappeared at high temperature. • The surface area decreased and the pore size increased with increasing of temperature. • Only MA/TiO{sub 2} (400) has a narrower band gap than pure g-C{sub 3}N{sub 4}. - Abstract: A composite of graphitic carbon nitride and TiO{sub 2} (g-C{sub 3}N{sub 4}/TiO{sub 2}) with enhanced photocatalytic hydrogen evolution capacity was achieved by calcining melamine and TiO{sub 2} sol-gel precursor. Characterization results reveal that heating temperature had a great influence on the structure, surface area and properties of the composites. Compared with the polycondensation of pure melamine, the presence of TiO{sub 2} precursor can promote the formation of melon at a low temperature. The highest photocatalytic activity of g-C{sub 3}N{sub 4}/TiO{sub 2}(400) was achieved when the calcination was performed at 400 °C, exhibiting H{sub 2} production rate of 76.25 μmol/h under UV–vis light irradiation (λ > 320 nm) and 35.44 μmol/h under visible light irradiation (λ > 420 nm). The highest photocatalytic performance of g-C{sub 3}N{sub 4}/TiO{sub 2}(400) can be attributed to: (1) the strong UV–vis light absorption due to the narrow bandgap caused by synergic effect of TiO{sub 2} and g-C{sub 3}N{sub 4}, (2) high surface area and porosity, (3) the effective separation of photo-generated electron-holes owing to the favorable heterojunction between TiO{sub 2} and g-C{sub 3}N{sub 4}.

  14. The amyloid interactome: Exploring protein aggregation.

    Directory of Open Access Journals (Sweden)

    Konstantina V Biza

    Full Text Available Protein-protein interactions are the quintessence of physiological activities, but also participate in pathological conditions. Amyloid formation, an abnormal protein-protein interaction process, is a widespread phenomenon in divergent proteins and peptides, resulting in a variety of aggregation disorders. The complexity of the mechanisms underlying amyloid formation/amyloidogenicity is a matter of great scientific interest, since their revelation will provide important insight on principles governing protein misfolding, self-assembly and aggregation. The implication of more than one protein in the progression of different aggregation disorders, together with the cited synergistic occurrence between amyloidogenic proteins, highlights the necessity for a more universal approach, during the study of these proteins. In an attempt to address this pivotal need we constructed and analyzed the human amyloid interactome, a protein-protein interaction network of amyloidogenic proteins and their experimentally verified interactors. This network assembled known interconnections between well-characterized amyloidogenic proteins and proteins related to amyloid fibril formation. The consecutive extended computational analysis revealed significant topological characteristics and unraveled the functional roles of all constituent elements. This study introduces a detailed protein map of amyloidogenicity that will aid immensely towards separate intervention strategies, specifically targeting sub-networks of significant nodes, in an attempt to design possible novel therapeutics for aggregation disorders.

  15. Aggregate Unemployment Decreases Individual Returns to Education

    Science.gov (United States)

    Ammermueller, Andreas; Kuckulenz, Anja; Zwick, Thomas

    2009-01-01

    Aggregate unemployment may affect individual returns to education through qualification-specific responses in participation and wage bargaining. This paper shows that an increase in regional unemployment by 1% decreases returns to education by 0.005 percentage points. This implies that higher skilled employees are better sheltered from labour…

  16. Simple statistical model for branched aggregates

    DEFF Research Database (Denmark)

    Lemarchand, Claire; Hansen, Jesper Schmidt

    2015-01-01

    We propose a statistical model that can reproduce the size distribution of any branched aggregate, including amylopectin, dendrimers, molecular clusters of monoalcohols, and asphaltene nanoaggregates. It is based on the conditional probability for one molecule to form a new bond with a molecule...

  17. 7 CFR 1.6 - Aggregating requests.

    Science.gov (United States)

    2010-01-01

    ... 7 Agriculture 1 2010-01-01 2010-01-01 false Aggregating requests. 1.6 Section 1.6 Agriculture... requests. When an agency reasonably believes that a requester, or a group of requesters acting in concert, is attempting to break a request down into a series of requests for the purpose of evading the...

  18. Comparative evaluation of mineral trioxide aggregate and ...

    African Journals Online (AJOL)

    overcome these limitations, various alternative formulations have been developed. Comparative evaluation of mineral trioxide aggregate and bioaggregate as apical barrier material in traumatized nonvital, immature teeth: A clinical pilot study. N Tuloglu, S Bayrak. Department of Pediatric Dentistry, Faculty of Dentistry, ...

  19. Carrier Aggregation for LTE-Advanced

    DEFF Research Database (Denmark)

    Pedersen, Klaus Ingemann; Frederiksen, Frank; Rosa, Claudio

    2011-01-01

    Carrier aggregation (CA) is one of the key features for LTE-Advanced. By means of CA, users gain access to a total bandwidth of up to 100 MHz in order to meet the IMT-Advanced requirements. The system bandwidth may be contiguous, or composed of several non-contiguous bandwidth chunks, which...

  20. Does it Matter How to Measure Aggregates?

    DEFF Research Database (Denmark)

    Beyer, Andreas; Juselius, Katarina

    Beyer, Doornik and Hendry (2000, 2001) show analytically that three out of four aggregation methods yield problematic results when exchange rate shifts induce relative-price changes between individual countries and found the least problematic method to be the variable weight method of growth rates...

  1. Utilitarian Aggregation of Beliefs and Tastes.

    Science.gov (United States)

    Gilboa, Itzhak; Samet, Dov; Schmeidler, David

    2004-01-01

    Harsanyi's utilitarianism is extended here to Savage's framework. We formulate a Pareto condition that implies that both society's utility function and its probability measure are linear combinations of those of the individuals. An indiscriminate Pareto condition has been shown to contradict linear aggregation of beliefs and tastes. We argue that…

  2. Colloidal Aggregate Structure under Shear by USANS

    Science.gov (United States)

    Chatterjee, Tirtha; van Dyk, Antony K.; Ginzburg, Valeriy V.; Nakatani, Alan I.

    2015-03-01

    Paints are complex formulations of polymeric binders, inorganic pigments, dispersants, surfactants, colorants, rheology modifiers, and other additives. A commercially successful paint exhibits a desired viscosity profile over a wide shear rate range from 10-5 s-1 for settling to >104 s-1 for rolling, and spray applications. Understanding paint formulation structure is critical as it governs the paint viscosity profile. However, probing paint formulation structure under shear is a challenging task due to the formulation complexity containing structures with different hierarchical length scales and their alterations under the influence of an external flow field. In this work mesoscale structures of paint formulations under shear are investigated using Ultra Small-Angle Neutron Scattering (rheo-USANS). Contrast match conditions were utilized to independently probe the structure of latex binder particle aggregates and the TiO2 pigment particle aggregates. Rheo-USANS data revealed that the aggregates are fractal in nature and their self-similarity dimensions and correlations lengths depend on the chemistry of the binder particles, the type of rheology modifier present and the shear stress imposed upon the formulation. These results can be explained in the framework of diffusion and reaction limited transient aggregates structure evolution under simple shear.

  3. Studies of the aggregation of RNase Sa

    DEFF Research Database (Denmark)

    Khasa, Harshit; Kramer, Ryan; Maddux, Nathan

    2014-01-01

    Thirty-eight mutants of RNase Sa (ribonuclease from Streptomyces aureofaciens) were examined for their structure, thermal sensitivity, and tendency to aggregate. Although a biphasic correlation was seen between the effect of temperature on structure and the free energy of transfer changes in many...

  4. Comparative evaluation of mineral trioxide aggregate and ...

    African Journals Online (AJOL)

    MTA) as an apical barrier material are limited, and no studies have so far examined the clinical performance of BioAggregate as apical barrier material in nonvital immature teeth. Aim: This study was aimed to provide a comparative evaluation of ...

  5. DENDRIMER CONJUGATES FOR SELECTIVE OF PROTEIN AGGREGATES

    DEFF Research Database (Denmark)

    2004-01-01

    Dendrimer conjugates are presented, which are formed between a dendrimer and a protein solubilising substance. Such dendrimer conjugates are effective in the treatment of protein aggregate-related diseases (e.g. prion-related diseases). The protein solubilising substance and the dendrimer together...

  6. Mechanical and thermal properties of prepacked aggregate ...

    Indian Academy of Sciences (India)

    Hossein Mohammadhosseini

    ashes into class N, class F and class C is not adequate to appraise their total usefulness, particularly for agricultural ashes. Considering the origin and type, this ash is, however, neither of class C nor of class F. 2.3 Concrete materials. The selection of coarse aggregate is of great importance with respect to the prepacked ...

  7. Mechanical and thermal properties of prepacked aggregate ...

    Indian Academy of Sciences (India)

    It has been found that POFA significantly reduces the temperature rise in prepacked aggregate concrete and delay the transfer of heat to the concrete body. The compressive and tensile strengths, however, increased with replacement up to20% POFA. The results obtained and the observation made in this study suggest that ...

  8. Globalization and Aggregate Employment Nexus: A Recent ...

    African Journals Online (AJOL)

    Contrary to these views, empirical results show that none of these does affect labour demand positively. As if that is not all, the impact of the ratio of total trade to non-oil GDP on aggregate employment is also negative. Since the result supports the view that higher propensity towards openness does not have any meaningful ...

  9. Lifting rationality assumptions in binary aggregation

    NARCIS (Netherlands)

    Grandi, U.; Endriss, U.

    2010-01-01

    We consider problems where several individuals each need to make a yes/no choice regarding a number of issues and these choices then need to be aggregated into a collective choice. Depending on the application at hand, different combinations of yes/no may be considered rational. We can describe such

  10. Surfactant effects on soil aggregate tensile strength

    Science.gov (United States)

    Little is known regarding a soil aggregate's tensile strength response to surfactants that may be applied to alleviate soil water repellency. Two laboratory investigations were performed to determine surfactant effects on the tensile strength of 1) Ap horizons of nine wettable, agricultural soils co...

  11. Comparative analysis of aggregate agricultural productivity between ...

    African Journals Online (AJOL)

    The study compared the aggregate agricultural productivity between the Low External Input Technology (LEIT) and High External Input Technology (HEIT) Farms in Imo State of Nigeria. The state is divided into three agricultural zones, out of which two were randomly selected for the study. Using a multistage sampling ...

  12. Aggregated Control of Domestic Heat Pumps

    DEFF Research Database (Denmark)

    Nielsen, Kirsten M.; Andersen, Palle; Pedersen, Tom S.

    2013-01-01

    A challenge in Denmark in the near future is to balance the electrical grid due to a large increase in the renewable energy production mainly from wind turbines. In this work an aggregated control system using heat pumps in single family houses to help balancing the grid is investigated. The cont...

  13. Face detection by aggregated Bayesian network classifiers

    NARCIS (Netherlands)

    Pham, T.V.; Worring, M.; Smeulders, A.W.M.

    2002-01-01

    A face detection system is presented. A new classification method using forest-structured Bayesian networks is used. The method is used in an aggregated classifier to discriminate face from non-face patterns. The process of generating non-face patterns is integrated with the construction of the

  14. Quasi-Species and Aggregate Dynamics

    DEFF Research Database (Denmark)

    Eriksson, Anders; Görnerup, Olof; Jacobi, Martin Nilsson

    2005-01-01

    At an early stage in pre-biotic evolution, groups of replicating molecules must coordinate their reproduction to form aggregated units of selection. Mechanisms that enable this to occur are currently not well understood. In this paper we introduce a deterministic model of primitive replicating ag...

  15. Kinetics of fibrilar aggregation of food proteins

    NARCIS (Netherlands)

    Arnaudov, L.N.

    2005-01-01

    In this thesis we study the kinetics of fibrilar aggregation of two model proteins widely used in the food industry -b-lactoglobulin (b-lg) and hen

  16. Metaconcrete: designed aggregates to enhance dynamic performance

    Science.gov (United States)

    Mitchell, Stephanie J.; Pandolfi, Anna; Ortiz, Michael

    2014-04-01

    We propose a new type of concrete for the attenuation of elastic waves induced by dynamic excitation. In this metamaterial, which we call metaconcrete, the stone, sand, and gravel aggregates of standard concrete are replaced with spherical inclusions consisting of a heavy metal core coated with a soft outer layer. These engineered aggregates can be tuned so that particular frequencies of a propagating blast wave will activate resonant oscillations of the heavy mass within the inclusions. The resonant behavior causes the system to exhibit negative effective mass, and this interaction between the wave motion and the resonant aggregates results in the attenuation of the applied dynamic loading. We introduce the concept of negative mass by deriving the effective momentum mass for the system and we define the geometrical and material parameters for the design of resonant aggregates. We develop finite element models for the analysis of metaconcrete behavior, defining a section of slab containing a periodic arrangement of inclusions. By computing the energy histories for the system when subject to a blast load, we show that there is a transfer of energy between the inclusions and the surrounding mortar. The inclusions are able to absorb a significant portion of the applied energy, resulting in a reduction in the amount of stress carried by the mortar phase and greatly improving the ability of the material to resist damage under explosive dynamic loading.

  17. Aggregation of log-linear risks

    DEFF Research Database (Denmark)

    Embrechts, Paul; Hashorva, Enkeleijd; Mikosch, Thomas Valentin

    2014-01-01

    In this paper we work in the framework of a k-dimensional vector of log-linear risks. Under weak conditions on the marginal tails and the dependence structure of a vector of positive risks, we derive the asymptotic tail behaviour of the aggregated risk {and present} an application concerning log...

  18. Waste polyethylene terephthalate as an aggregate in concrete

    Directory of Open Access Journals (Sweden)

    Nabajyoti Saikia

    2013-04-01

    Full Text Available This paper reports the strength behaviour of concrete containing three types of recycled polyethylene terephthalate (PET aggregate. Results are also analysed to determine the PET-aggregate's effect on the relationship between the flexural and splitting tensile strengths and compressive strength and to know whether the relationships between compressive strength and other strength characteristics given in European design codes are applicable to concrete made with PET-aggregates. The compressive strength development of concrete containing all types of PET-aggregate behaves like in conventional concrete, though the incorporation of any type of PET-aggregate significantly lowers the compressive strength of the resulting concrete. The PET-aggregate incorporation improves the toughness behaviour of the resulting concrete. This behaviour is dependent on PET-aggregate's shape and is maximised for concrete containing coarse, flaky PET-aggregate. The splitting tensile and flexural strength characteristics are proportional to the loss in compressive strength of concrete containing plastic aggregates.

  19. Transportation and utilization of aggregates for road construction

    Science.gov (United States)

    Fladvad, Marit; Wigum, Børge Johannes; Aurstad, Joralf

    2017-04-01

    Road construction relies on non-renewable aggregate resources as the main construction material. Sources for high-quality aggregate resources are scattered, and requirements for aggregate quality can cause long transport distances between quarry and road construction site. In European countries, the average aggregate consumption per capita is 5 tonnes per year (European Aggregates Association, 2016), while the corresponding figure for Norway is 11 tonnes (Neeb, 2015). Half the Norwegian aggregate production (sand, gravel and crushed rock) is used for road construction. In Norway, aggregate resources have been considered abundant. However, stricter requirement for aggregate quality, and increased concern for sustainability and environmental issues have spurred focus on reduction of transport lengths through better utilization of local aggregate materials. In this research project, information about pavement design and aggregate quality requirements were gathered from a questionnaire sent to selected experts from the World Road Organization (PIARC), European Committee for Standardization (CEN), and Nordic Road Association (NVF). The gathered data was compared to identify differences and similarities for aggregate use in the participating countries. Further, the data was compared to known data from Norway regarding: - amount of aggregates required for a road structure - aggregate transport lengths and related costs A total of 18 countries participated in the survey, represented by either road authorities, research institutions, or contractors. There are large variations in practice for aggregate use among the represented countries, and the selection of countries is sufficient to illustrate a variety in pavement designs, aggregate sizes, and quality requirements for road construction. There are considerable differences in both pavement thickness and aggregate sizes used in the studied countries. Total thicknesses for pavement structures varies from 220 mm to 2400 mm

  20. Copper-triggered aggregation of ubiquitin.

    Directory of Open Access Journals (Sweden)

    Fabio Arnesano

    Full Text Available Neurodegenerative disorders share common features comprising aggregation of misfolded proteins, failure of the ubiquitin-proteasome system, and increased levels of metal ions in the brain. Protein aggregates within affected cells often contain ubiquitin, however no report has focused on the aggregation propensity of this protein. Recently it was shown that copper, differently from zinc, nickel, aluminum, or cadmium, compromises ubiquitin stability and binds to the N-terminus with 0.1 micromolar affinity. This paper addresses the role of copper upon ubiquitin aggregation. In water, incubation with Cu(II leads to formation of spherical particles that can progress from dimers to larger conglomerates. These spherical oligomers are SDS-resistant and are destroyed upon Cu(II chelation or reduction to Cu(I. In water/trifluoroethanol (80:20, v/v, a mimic of the local decrease in dielectric constant experienced in proximity to a membrane surface, ubiquitin incubation with Cu(II causes time-dependent changes in circular dichroism and Fourier-transform infrared spectra, indicative of increasing beta-sheet content. Analysis by atomic force and transmission electron microscopy reveals, in the given order, formation of spherical particles consistent with the size of early oligomers detected by gel electrophoresis, clustering of these particles in straight and curved chains, formation of ring structures, growth of trigonal branches from the rings, coalescence of the trigonal branched structures in a network. Notably, none of these ubiquitin aggregates was positive to tests for amyloid and Cu(II chelation or reduction produced aggregate disassembly. The early formed Cu(II-stabilized spherical oligomers, when reconstituted in 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC liposomes and in POPC planar bilayers, form annular and pore-like structures, respectively, which are common to several neurodegenerative disorders including Parkinson's, Alzheimer

  1. Practical problems in aggregating expert opinions

    Energy Technology Data Exchange (ETDEWEB)

    Booker, J.M.; Picard, R.R.; Meyer, M.A.

    1993-11-01

    Expert opinion is data given by a qualified person in response to a technical question. In these analyses, expert opinion provides information where other data are either sparse or non-existent. Improvements in forecasting result from the advantageous addition of expert opinion to observed data in many areas, such as meteorology and econometrics. More generally, analyses of large, complex systems often involve experts on various components of the system supplying input to a decision process; applications include such wide-ranging areas as nuclear reactor safety, management science, and seismology. For large or complex applications, no single expert may be knowledgeable enough about the entire application. In other problems, decision makers may find it comforting that a consensus or aggregation of opinions is usually better than a single opinion. Many risk and reliability studies require a single estimate for modeling, analysis, reporting, and decision making purposes. For problems with large uncertainties, the strategy of combining as diverse a set of experts as possible hedges against underestimation of that uncertainty. Decision makers are frequently faced with the task of selecting the experts and combining their opinions. However, the aggregation is often the responsibility of an analyst. Whether the decision maker or the analyst does the aggregation, the input for it, such as providing weights for experts or estimating other parameters, is imperfect owing to a lack of omniscience. Aggregation methods for expert opinions have existed for over thirty years; yet many of the difficulties with their use remain unresolved. The bulk of these problem areas are summarized in the sections that follow: sensitivities of results to assumptions, weights for experts, correlation of experts, and handling uncertainties. The purpose of this paper is to discuss the sources of these problems and describe their effects on aggregation.

  2. Probabilistic Analysis of Structural Member from Recycled Aggregate Concrete

    Science.gov (United States)

    Broukalová, I.; Šeps, K.

    2017-09-01

    The paper aims at the topic of sustainable building concerning recycling of waste rubble concrete from demolition. Considering demands of maximising recycled aggregate use and minimising of cement consumption, composite from recycled concrete aggregate was proposed. The objective of the presented investigations was to verify feasibility of the recycled aggregate cement based fibre reinforced composite in a structural member. Reliability of wall from recycled aggregate fibre reinforced composite was assessed in a probabilistic analysis of a load-bearing capacity of the wall. The applicability of recycled aggregate fibre reinforced concrete in structural applications was demonstrated. The outcomes refer to issue of high scatter of material parameters of recycled aggregate concretes.

  3. Autoimmune Responses to Soluble Aggregates of Amyloidogenic Proteins Involved in Neurodegenerative Diseases: Overlapping Aggregation Prone and Autoimmunogenic regions

    Science.gov (United States)

    Kumar, Sandeep; Thangakani, A. Mary; Nagarajan, R.; Singh, Satish K.; Velmurugan, D.; Gromiha, M. Michael

    2016-01-01

    Why do patients suffering from neurodegenerative diseases generate autoantibodies that selectively bind soluble aggregates of amyloidogenic proteins? Presently, molecular basis of interactions between the soluble aggregates and human immune system is unknown. By analyzing sequences of experimentally validated T-cell autoimmune epitopes, aggregating peptides, amyloidogenic proteins and randomly generated peptides, here we report overlapping regions that likely drive aggregation as well as generate autoantibodies against the aggregates. Sequence features, that make short peptides susceptible to aggregation, increase their incidence in human T-cell autoimmune epitopes by 4–6 times. Many epitopes are predicted to be significantly aggregation prone (aggregation propensities ≥10%) and the ones containing experimentally validated aggregating regions are enriched in hydrophobicity by 10–20%. Aggregate morphologies also influence Human Leukocyte Antigen (HLA) - types recognized by the aggregating regions containing epitopes. Most (88%) epitopes that contain amyloid fibril forming regions bind HLA-DR, while majority (63%) of those containing amorphous β-aggregating regions bind HLA-DQ. More than two-thirds (70%) of human amyloidogenic proteins contain overlapping regions that are simultaneously aggregation prone and auto-immunogenic. Such regions help clear soluble aggregates by generating selective autoantibodies against them. This can be harnessed for early diagnosis of proteinopathies and for drug/vaccine design against them. PMID:26924748

  4. Enhanced Removal of Arsenic and Antimony in the Mining Site by Calcined γ-Fe2O3/Layered Double Hydroxide Nanocomposite

    Science.gov (United States)

    Lee, Sang-Ho; Choi, Heechul; Kim, Kyoung-Woong

    2016-04-01

    Arsenic (As) and Antimony (Sb) have been recognized as harmful contaminants in aquatic environment due to its high toxicity and carcinogenicity. Especially, the contamination of arsenic in the mining areas is considered as a serious emerging environmental issue in Korea. Due to the hazardous effect of arsenic, the United States Environmental Protection Agency (US EPA) regulated maximum contamination level of arsenic to 10 μg/L in drinking water. The harmful effect on human health by excessive intake of antimony was also reported by previous studies, and severe contamination level (100 - 7,000 μg/L) of antimony reported in surface and groundwater of abandoned mining area in China and Slovakia. Therefore, US EPA regulated maximum contaminants level of antimony in drinking water to 6 μg/L. In order to remove anionic contaminants in drinking water, various type of nanomaterials have been developed. Layered double hydroxide (LDH) is the artificial anionic clay that is based on the layered structure of positively charged brucite-like layers with interlayers of anions. The LDH is one of the promising nanomaterials for the removal of anionic contaminants because it has high selectivity for arsenic, phosphate, chromium and antimony. However, the biggest problem of LDH for wastewater treatment is that the particles cannot be easily separated after the removal of contaminants. In this study, magnetic nanoparticles (γ-Fe2O3) supported LDH nanocomposite (γ-Fe2O3/LDH) was investigated to enhance magnetic particle recovery and removal efficiency for arsenic and antimony. The calcined γ-Fe2O3/LDH nanocomposites synthesized by co-precipitation method, and the crystallographic properties of maghemite (γ-Fe2O3) and layered structure of LDH were confirmed by X-ray diffraction. The nano-sized γ-Fe2O3 (30 to 50 nm) was stably attached on the surface of LDH (100 to 150 nm) and O1s spectrum by X-ray photoelectron spectroscopy (XPS) explained that there are both physical and

  5. Structural evolution during calcination and sintering of a (La0.6Sr0.4)0.99CoO3-δ nanofiber prepared by electrospinning

    Science.gov (United States)

    Simonsen, S. B.; Shao, J.; Zhang, W.

    2017-06-01

    Design of three-dimensional metal oxide nanofibers by electrospinning is being widely explored. However, the impacts of calcination and sintering on the resulting morphology remain unknown. For the first time, (La0.6Sr0.4)0.99CoO3-δ (LSC) nanofiber, which is among the most promising electrode materials for solid oxide fuel cells, was synthesized by sol-gel electrospinning. By elevating the temperature in oxygen using in situ transmission electron microscopy, we discovered the structural transitions from nanofibers to nanotubes and then to nano-pearl strings. This facile and up-scalable method can be widely applied to design metal oxide one-dimensional nanomaterials with precise control in both geometry (nanofiber, nanotube and nano-pearl string) and surface area (by varying grain size).

  6. Structure and photoluminescence property of Eu-doped SnO{sub 2} nanocrystalline powders fabricated by sol-gel calcination process

    Energy Technology Data Exchange (ETDEWEB)

    Chen Jiangtao; Wang Jun; Zhang Fei; Yan De; Zhang Guangan; Zhuo Renfu; Yan Pengxun [School of Physical Science and Technology, Lanzhou University, Lanzhou 730000 (China)], E-mail: pxyan@lzu.edu.cn

    2008-05-21

    Eu-doped SnO{sub 2} nanocrystalline powders were fabricated by the sol-gel calcination process. The effect of Eu doping concentrations on the structure and photoluminescence properties of Eu-doped SnO{sub 2} nanocrystalline powders was investigated. X-ray diffraction patterns, Fourier transformation infrared spectrum, field emission scanning electron microscope and high-resolution transmission electron microscope are employed to investigate the morphology and the structure of Eu-doped SnO{sub 2} nanocrystalline powders. The samples display reddish-orange light and red light when excited at indirect and direct excitation, respectively. Meanwhile, PL spectra indicate that the quenching concentrations are different when the excitation wavelength alters. Based on the analysis of the PL spectra, it is believed that Eu{sup 3+} ions located at different sites in the SnO{sub 2} host are selectively excited.

  7. Properties of Concrete with Tire Derived Aggregate Partially Replacing Coarse Aggregates

    Science.gov (United States)

    Siringi, Gideon; Abolmaali, Ali; Aswath, Pranesh B.

    2015-01-01

    Tire derived aggregate (TDA) has been proposed as a possible lightweight replacement for mineral aggregate in concrete. The role played by the amount of TDA replacing coarse aggregate as well as different treatment and additives in concrete on its properties is examined. Conventional concrete (without TDA) and concrete containing TDA are compared by examining their compressive strength based on ASTM C39, workability based on ASTM C143, splitting tensile strength based on ASTM C496, modulus of rupture (flexural strength) based on ASTM C78, and bond stress based on ASTM C234. Results indicate that while replacement of coarse aggregates with TDA results in reduction in strength, it may be mitigated with addition of silica fume to obtain the desired strength. The greatest benefit of using TDA is in the development of a higher ductile product while utilizing recycled TDA. PMID:26161440

  8. Properties of Concrete with Tire Derived Aggregate Partially Replacing Coarse Aggregates

    Directory of Open Access Journals (Sweden)

    Gideon Siringi

    2015-01-01

    Full Text Available Tire derived aggregate (TDA has been proposed as a possible lightweight replacement for mineral aggregate in concrete. The role played by the amount of TDA replacing coarse aggregate as well as different treatment and additives in concrete on its properties is examined. Conventional concrete (without TDA and concrete containing TDA are compared by examining their compressive strength based on ASTM C39, workability based on ASTM C143, splitting tensile strength based on ASTM C496, modulus of rupture (flexural strength based on ASTM C78, and bond stress based on ASTM C234. Results indicate that while replacement of coarse aggregates with TDA results in reduction in strength, it may be mitigated with addition of silica fume to obtain the desired strength. The greatest benefit of using TDA is in the development of a higher ductile product while utilizing recycled TDA.

  9. Mechanical properties of concrete containing recycled concrete aggregate (RCA) and ceramic waste as coarse aggregate replacement

    Science.gov (United States)

    Khalid, Faisal Sheikh; Azmi, Nurul Bazilah; Sumandi, Khairul Azwa Syafiq Mohd; Mazenan, Puteri Natasya

    2017-10-01

    Many construction and development activities today consume large amounts of concrete. The amount of construction waste is also increasing because of the demolition process. Much of this waste can be recycled to produce new products and increase the sustainability of construction projects. As recyclable construction wastes, concrete and ceramic can replace the natural aggregate in concrete because of their hard and strong physical properties. This research used 25%, 35%, and 45% recycled concrete aggregate (RCA) and ceramic waste as coarse aggregate in producing concrete. Several tests, such as concrete cube compression and splitting tensile tests, were also performed to determine and compare the mechanical properties of the recycled concrete with those of the normal concrete that contains 100% natural aggregate. The concrete containing 35% RCA and 35% ceramic waste showed the best properties compared with the normal concrete.

  10. Influence of granitic aggregates from Northeast Brazil on the alkali-aggregate reaction

    Energy Technology Data Exchange (ETDEWEB)

    Gomes Neto, David de Paiva; Santana, Rodrigo Soares de; Barreto, Ledjane Silva, E-mail: pvgomes@uol.com.br [Universidade Federal de Sergipe (UFS), Sao Cristovao, SE (Brazil). Dept. de Ciencias dos Materiais e Engenharia; Conceicao, Herbert; Lisboa, Vinicios Anselmo Carvalho [Universidade Federal de Sergipe (UFS), Sao Cristovao, SE (Brazil). Dept. de Geologia

    2014-08-15

    The alkali-aggregate reaction (AAR) in concrete structures is a problem that has concerned engineers and researchers for decades. This reaction occurs when silicates in the aggregates react with the alkalis, forming an expanded gel that can cause cracks in the concrete and reduce its lifespan. The aim of this study was to characterize three coarse granitic aggregates employed in concrete production in northeastern Brazil, correlating petrographic analysis with the kinetics of silica dissolution and the evolution of expansions in mortar bars, assisted by SEM/EDS, XRD, and EDX. The presence of grains showing recrystallization into individual microcrystalline quartz subgrains was associated with faster dissolution of silica and greater expansion in mortar bars. Aggregates showing substantial deformation, such as stretched grains of quartz with strong undulatory extinction, experienced slower dissolution, with reaction and expansion occurring over longer periods that could not be detected using accelerated tests with mortar bars. (author)

  11. Properties of Concrete with Tire Derived Aggregate Partially Replacing Coarse Aggregates.

    Science.gov (United States)

    Siringi, Gideon; Abolmaali, Ali; Aswath, Pranesh B

    2015-01-01

    Tire derived aggregate (TDA) has been proposed as a possible lightweight replacement for mineral aggregate in concrete. The role played by the amount of TDA replacing coarse aggregate as well as different treatment and additives in concrete on its properties is examined. Conventional concrete (without TDA) and concrete containing TDA are compared by examining their compressive strength based on ASTM C39, workability based on ASTM C143, splitting tensile strength based on ASTM C496, modulus of rupture (flexural strength) based on ASTM C78, and bond stress based on ASTM C234. Results indicate that while replacement of coarse aggregates with TDA results in reduction in strength, it may be mitigated with addition of silica fume to obtain the desired strength. The greatest benefit of using TDA is in the development of a higher ductile product while utilizing recycled TDA.

  12. Fabrication and characterization of ZnO nanowires array electrodes with high photocurrent densities: Effects of the seed layer calcination time

    Energy Technology Data Exchange (ETDEWEB)

    Lu, Yi-Jing; Liu, Ching-Fang; Hu, Chi-Chang, E-mail: cchu@che.nthu.edu.tw; Kuo, Jen-Hou; Boddula, Rajender

    2017-03-01

    In this work, we demonstrate that vertically grown ZnO nanowire (NW) arrays of the wurzite phase were successfully fabricated on fluorine doped tin oxide (FTO) substrates via a hydrothermal method. The coating of a seed layer onto the FTO substrates was found to favor the growth of a uniform ZnO NWs array which shows saturation in the photocurrent density with a relatively low potential bias. Furthermore, prolonging the calcination time of the seed layer makes the ZnO NWs behave the better charge separation and improve the photo-electrochemical performance. Under the irradiation at a 75 mW cm{sup −2} from a simulated sunlight source, the ZnO NWs array electrode prepared from the seed layer with calcination at 350 °C for 5 h shows a saturated photocurrent density of 514 μA cm{sup −2} and a maximum half-cell solar-to-hydrogen (HC-STH) efficiency of 0.26% was obtained at 0.6 V versus reversible hydrogen electrode (RHE) in neutral electrolyte. - Highlights: • The seed layer annealing time strongly influences the textural and photo-activity of ZnO NWs. • The average diameter and density of ZnO NWs were controlled to 47–70 nm and 46–70 NWs μm{sup −2}, respectively. • ZnO NWs show promising application potential in solar-electrocatalytic water splitting under potential bias. • The ZnO NWs with SL annealing time = 5 h achieve the highest HC-STH efficiency of 0.26% at 0.6 V.

  13. MoO3/SiO2-ZrO2 Catalyst: Eeffect of Calcination Temperature on Physico-chemical Properties and Activities in Nitration of Toluene

    Directory of Open Access Journals (Sweden)

    Sunil Madhavrao Kemdeo

    2012-12-01

    Full Text Available 12 wt % molybdena was deposited over 1:1 silica zirconia mixed oxide support and the resultant catalyst was calcined between the 500 to 700 oC range of temperature. The samples were characterized by XRD, FT-IR, BET, SEM, NH3-TPD and pyridine adsorbed FT-IR techniques.  Nitration of toluene was studied as a model reaction over the prepared catalysts and parameters like effect of reaction temperature, effect of various solvents, catalyst reusability are studied. It was found that conversion of toluene varies with the presence of Brönsted acid sites over the catalyst surface and para-nitrotoulene selectivity is associated with pore size of the catalyst. Over the same catalysts, nitration was extended for some other aromatics. Avoid of sulfuric acid in the present process is an interesting concern in view of green chemistry. Copyright © 2012 by BCREC UNDIP. All rights reservedKeywords: MoO3/SiO2-ZrO2; SO2-ZrO2; NH3-TPD; Nitration; ortho-nitro tolueneReceived: 19th May 2012, Revised: 24th May 2012, Accepted: 26th May 2012[How to Cite: S.M. Kemdeo. (2012. MoO3/SiO2-ZrO2 Catalyst: Effect of Calcination Temperature on Physico-chemical Properties and Activities in Nitration of Toluene. Bulletin of Chemical Reaction Engineering & Catalysis, 7 (2: 92-104. doi:10.9767/bcrec.7.2.3521.92-104] [How to Link / DOI: http://dx.doi.org/10.9767/bcrec.7.2.3521.92-104 || or local: http://ejournal.undip.ac.id/index.php/bcrec/article/view/3521] | View in 

  14. Relationships between aggregates size classes and SOC content using aggregate settling velocity measurements in interrill areas

    Science.gov (United States)

    Quijano, Laura; Kuhn, Nikolaus J.; Navas, Ana

    2017-04-01

    Soil aggregate stability is one of the main factors of soil physics and structure. Formation and stabilization of soil aggregates facilitates soil carbon sequestration and reduces the susceptibility of soil to erosion. The gain or loss of C in agricultural systems is largely influenced by aggregate-associated soil organic carbon that affects the settling velocity and C content of soils. Settling velocity measurements are useful to provide direct information on soil aggregate size distribution that can be used as indicators of the potential soil erodibility. This study aims to analyze the effect of settling velocity on soil aggregate dynamics and the relationships between the particle size distributions and the associated carbon in a cultivated field of typical Mediterranean agroecosystems in mountain landscapes. Calcisol topsoil samples (n=10) were collected in an interrill area within the field at two contrasting slope positions (i.e. upslope and downslope). Furthermore, a total of ten Calcisol soil samples were collected in an adjacent area under forest vegetation cover and stable conditions. According to Stokes's Law, the fine soil fraction 0.045, 0.045-0.015, 0.015-0.003, 0.003-0.001 and soil aggregation by the lower proportion of macroaggregates compared to forest soils. Moreover, it was found a preferential transport of fine particles from upslope to downslope during interrill erosion processes. In this study, settling velocity measurements provide a useful tool for assessing changes in soil aggregation under different land uses and for identifying the relationship between aggregates size classes and SOC content in Mediterranean agroecosystems.

  15. Biological framework for soil aggregation: Implications for ecological functions.

    Science.gov (United States)

    Ghezzehei, Teamrat; Or, Dani

    2016-04-01

    Soil aggregation is heuristically understood as agglomeration of primary particles bound together by biotic and abiotic cementing agents. The organization of aggregates is believed to be hierarchical in nature; whereby primary particles bond together to form secondary particles and subsequently merge to form larger aggregates. Soil aggregates are not permanent structures, they continuously change in response to internal and external forces and other drivers, including moisture, capillary pressure, temperature, biological activity, and human disturbances. Soil aggregation processes and the resulting functionality span multiple spatial and temporal scales. The intertwined biological and physical nature of soil aggregation, and the time scales involved precluded a universally applicable and quantifiable framework for characterizing the nature and function of soil aggregation. We introduce a biophysical framework of soil aggregation that considers the various modes and factors of the genesis, maturation and degradation of soil aggregates including wetting/drying cycles, soil mechanical processes, biological activity and the nature of primary soil particles. The framework attempts to disentangle mechanical (compaction and soil fragmentation) from in-situ biophysical aggregation and provides a consistent description of aggregate size, hierarchical organization, and life time. It also enables quantitative description of biotic and abiotic functions of soil aggregates including diffusion and storage of mass and energy as well as role of aggregates as hot spots of nutrient accumulation, biodiversity, and biogeochemical cycles.

  16. Estudio de la adición de arcillas calcinadas en la durabilidad de hormigones Study of the addition of calcined clays in the durability of concrete

    Directory of Open Access Journals (Sweden)

    Rancés Castillo Lara

    2011-01-01

    conveniente para el hormigón ante la posible acción de diferentes mecanismos de degradación.Currently economical and environmental advantages of cement clinker replacement by other supplementary cementious materials are well known. For example calcined clays, such as metakaolin, have drawn special attention during recent years. It is well known that these admixtures added to mortars and concretes improve mechanical strength as well as durability. The purpose of this study is to evaluate the behavior of physical-mechanical properties and durability in micro-concretes, by employing calcinated and grinded clays as replacement material, by 30% of ordinary Portland cement (OPC. Therefore, clay soil was employed, which is mainly composed by low-purity-kaolin mineral, so as to obtain calcined clays to be used as supplementary cementious minerals. Best results for compressive strength at 28 days were obtained by sedimentary calcined clays, which have higher content of kaolin mineral thanks to a purification process by means of raw material sedimentation conducted on this admixture only. Nevertheless, capillary water absorption tests delivered best results for calcined clay soil, which finesse is quite high. Lower values showed by this admixture, as much for capillary porosity and sorptivity, revealed there was a predominance of compaction and impermeability phenomena achieved by cementious matrix using such fine material, over the effect of puzzolanic reaction. Micro-structure studies on C-S-H gel, employing energy dispersive x-ray (EDX technique, demonstrated that the use of calcined clays as replacement of RPC favors the creation of quite stable hydration products, mainly monosulfos of hemicabo and monocarbo types, which is convenient for concrete against possible deterioration actions from different mechanisms.

  17. Turbulence control of suspended matter aggregate size

    Science.gov (United States)

    Jago, C. F.; Jones, S. E.; Rippeth, T. P.; Simpson, J. H.

    2003-04-01

    The size and properties of the aggregates which comprise suspended particulate matter (SPM) change on short time and length scales in shelf seas. There is experimental and theoretical evidence to suggest that turbulence plays a key role in aggregation but there is contradictory evidence with respect to disaggregation: it has been proposed that sinking stresses, rather than turbulent stresses, are the dominant control of disaggregation. But there is little observational evidence for turbulence control of particle properties. New observations are presented which provide compelling evidence for turbulence control of both aggregation and disaggregation. TKE dissipation and particle size were measured in situ at stratified sites in the northern North Sea in 110 m water depth during the period of weakening of the seasonal thermocline (in October/November) and in the Clyde Sea in 55 m water depth (April). There were similar vertical distributions of TKE dissipation E, SPM concentration C, and particle size D at both sites. At the base of the thermocline, there were minima in E and C, but a maximum in D, indicating that enhanced aggregation was occurring in this region of low turbulent stress. In the bottom mixed layer, E and C increased, while D decreased due to disaggregation in this region of increasing turbulent stress towards the seabed. Particles settling out of the low stress region at the base of the thermocline began to disaggregate when E increased to 3.2x10-6 watts m-2. D did not correlate directly with E because aggregation is a function of collision frequency (and hence of both C and E): this can be accounted for using a simplified theoretical aggregation model which treats flocs as self-similar fractal entities and allows simultaneous floc formation and break up, specified as functions of C and E. It was found that in the northern North Sea the measured D represents an equilibrium size predicted by the model, while in the Clyde Sea tidal variation in both C

  18. Improvement of Bearing Capacity in Recycled Aggregates Suitable for Use as Unbound Road Sub-Base

    OpenAIRE

    Laura Garach; Mónica López; Francisco Agrela; Javier Ordóñez; Javier Alegre; José Antonio Moya

    2015-01-01

    Recycled concrete aggregates and mixed recycled aggregates are specified as types of aggregates with lower densities, higher water absorption capacities, and lower mechanical strength than natural aggregates. In this paper, the mechanical behaviour and microstructural properties of natural aggregates, recycled concrete aggregates and mixed recycled aggregates were compared. Different specimens of unbound recycled mixtures demonstrated increased resistance properties. The formation of new ceme...

  19. Pore structure of natural and regenerated soil aggregates

    DEFF Research Database (Denmark)

    Naveed, Muhammad; Arthur, Emmanuel; de Jonge, Lis Wollesen

    2014-01-01

    Quantitative characterization of aggregate pore structure can reveal the evolution of aggregates under different land use and management practices and their effects on soil processes and functions. Advances in X-ray Computed Tomography (CT) provide powerful means to conduct such characterization....... This study examined aggregate pore structure of three differently managed same textured Danish soils (mixed forage cropping, MFC; mixed cash cropping, MCC; cereal cash cropping, CCC) for (i) natural aggregates, and (ii) aggregates regenerated after 20 months of incubation. In total, 27 aggregates (8-16 mm......) were sampled from nine different treatments; 3 natural soils and 3 repacked lysimeters without and 3 with organic matter (ground rape) amendment. Three dimensional X-ray CT images, tensile strength, and organic carbon were obtained for each aggregate. Aggregate-associated organic carbon differed...

  20. 47 CFR 10.300 - Alert aggregator. [Reserved

    Science.gov (United States)

    2010-10-01

    ... 47 Telecommunication 1 2010-10-01 2010-10-01 false Alert aggregator. 10.300 Section 10.300 Telecommunication FEDERAL COMMUNICATIONS COMMISSION GENERAL COMMERCIAL MOBILE ALERT SYSTEM System Architecture § 10.300 Alert aggregator. ...