WorldWideScience

Sample records for calcined aggregates

  1. Physical Properties of Calcined Kaolin (Kibi,Ghana) Aggregate Refractory Bodies

    Institute of Scientific and Technical Information of China (English)

    K.Amoako-Appiagyei

    1998-01-01

    Properties of refractories affect their perfor-mance and deformation behaviour as well as their ultimate failure mode,Therefore in ordr to assess the capabilities of materials,used for refractory lin-ings,in service their properties must be evaluated.In this work the evaluation of some physical properties of calcined kaloin(Kibi,Ghana)aggregate re-fractory bodies showed an average porosity and spe-cific gravity of 24% and 2.78 respectively,An av-erage cold crushing strength of 19.6 MPa was also obtained .Thermal expansion and behaviour under a constant hot load of 196 kPa also showed good resis-tance to high temperature deformation.

  2. [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.

  3. 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.

  4. Spray calcination of nuclear wastes

    Energy Technology Data Exchange (ETDEWEB)

    Bonner, W.F.; Blair, H.T.; Romero, L.S.

    1976-01-01

    The spray calciner is a relatively simple machine; operation is simple and is easily automated. Startup and shutdown can be performed in less than an hour. A wide variety of waste compositions and concentrations can be calcined under easily maintainable conditions. Spray calcination of all commercial fuel reprocessor high-level liquid wastes and mixed high and intermediate-level wastes have been demonstrated. Wastes have been calcined containing over 2M sodium. Thus waste generated during plant startup and shutdown can be blended with normal waste and calcined. Spray calcination of ILLW has also been demonstrated. A remotely replaceable atomizing nozzle has been developed for use in plant scale equipment. The 6 mm (0.25 inch) orifice and ceramic tip offer freedom from plugging and erosion thus nozzle replacement should be required only after several months operation. Calciner capacity of over 75 l/h (20 gal/h) has been demonstrated in pilot scale equipment. Sintered stainless steel filters are effective in deentraining over 99.9 percent of the solids that result from calcining the feedstock. Since such a small amount of radionuclides escape the calciner the volume of recycle required from the effluent treatment system is very small. The noncondensable off-gas volume is also low, less than 0.5 m/sup 3//min (15 scfm) for a liquid feedrate of 75 l/hr (20 gal/hr). Calcine holdup in the calciner is less than 1 kg, thus the liquid feedrate is directly relatable to calcine flowrate. The calcine produced is very fine and reactive. Successful remote operation and maintenance of a heated wall spray calciner has been demonstrated while processing actual high-level waste. During these operations radionuclide volatilization from the calciner was acceptably low. 8 figures. (DLC)

  5. Fluidized bed calciner apparatus

    Science.gov (United States)

    Owen, Thomas J.; Klem, Jr., Michael J.; Cash, Robert J.

    1988-01-01

    An apparatus for remotely calcining a slurry or solution feed stream of toxic or hazardous material, such as ammonium diurante slurry or uranyl nitrate solution, is disclosed. The calcining apparatus includes a vertical substantially cylindrical inner shell disposed in a vertical substantially cylindrical outer shell, in which inner shell is disposed a fluidized bed comprising the feed stream material to be calcined and spherical beads to aid in heat transfer. Extending through the outer and inner shells is a feed nozzle for delivering feed material or a cleaning chemical to the beads. Disposed in and extending across the lower portion of the inner shell and upstream of the fluidized bed is a support member for supporting the fluidized bed, the support member having uniform slots for directing uniform gas flow to the fluidized bed from a fluidizing gas orifice disposed upstream of the support member. Disposed in the lower portion of the inner shell are a plurality of internal electric resistance heaters for heating the fluidized bed. Disposed circumferentially about the outside length of the inner shell are a plurality of external heaters for heating the inner shell thereby heating the fluidized bed. Further, connected to the internal and external heaters is a means for maintaining the fluidized bed temperature to within plus or minus approximately 25.degree. C. of a predetermined bed temperature. Disposed about the external heaters is the outer shell for providing radiative heat reflection back to the inner shell.

  6. 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.

  7. 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.

  8. 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

  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. Utilização de massas cerâmicas na produção de agregado sintético de argila calcinada para uso em concreto Use of ceramic bodies in the production of synthetic aggregate calcined clay for use in concrete

    Directory of Open Access Journals (Sweden)

    E. M. Cabral

    2008-12-01

    manufacturing synthetic aggregate of calcined clay for use in concrete. The ceramic pastes were analyzed by X-ray diffraction, evaluation of chemical composition, particle size distribution and plasticity. The samples were prepared by uniaxial pressing at 20 MPa and calcined at 850, 950, 1050 and 1150 ºC. The technological properties evaluated were: linear shrinkage, water absorption, apparent specific mass and vitrification temperature. The ceramic paste that presented the smallest apparent specific mass and smallest percentile of molding humidity was chosen for synthetic aggregate. The results obtained for the concrete produced with the synthetic aggregate of calcined clay show its potential as a substitute of the natural aggregate of the Amazonic region, the natural gravel.

  11. Dissolution properties of calcined gangue

    Institute of Scientific and Technical Information of China (English)

    Huajian Li; Henghu Sun; Xuchu Tie; Xuejun Xiao

    2006-01-01

    To study the dissolution mechanism of gangue, dissolution characteristics of the gangue samples calcined at different temperatures in alkaline solutions and alkali metal silicate solutions with respect to Si and A1 ions were analyzed by identical coupled plasma optical emission spectroscopy (ICP). The results show that the extent of dissolution of A1 and Si varies with calcination temperature. It shows that the samples have a higher degree of dissolution in NaOH than in KOH medium. Si and A1 appear to have synchro-dissolution behavior in alkaline solution, which means that Si and A1 could dissolve from the mineral surface in certain linked forms. The result that a higher degree of dissolution exists in sodium silicate solution and a lower degree of dissolution exists in sodium-potassium silicate solution of A1 is proved by the 29Si NMR spectra and the mean connectivity degree of these alkali metal silicate solutions.

  12. Effect of fly ash calcination in geopolymer synthesis

    Science.gov (United States)

    Samadhi, Tjokorde Walmiki; Jatiningrum, Mirna; Arisiani, Gresia

    2015-12-01

    Geopolymer, a largely amorphous class of inorganic polymer consisting of aluminosilicate repeat units, is an environmentally attractive engineering material due to its ability to consume aluminosilicate waste as raw materials. This work studies the effect of the calcination temperature of a coal fly ash generated by a low-efficiency boiler on the mechanical strength of geopolymer mortar synthesized using a mixture of the fly ash, potassium hydroxide as the alkali activator, and locally available sand as the filler aggregate. The calcination temperature is varied between 500-700 °C, with a calcination period of 2 hours in an electric furnace. Two sand samples with different particle size distributions are used. The key response variable is the compressive strength at room temperature, measured after curing at 80 °C for 7 and 14 days. Uncalcined ash, with a carbon content of approximately 31.0%, is not amenable for geopolymer synthesis. Analysis of experimental data using the ANOVA method for general factorial design identifies significant main effects for all three experimental variables. Two-way interactions are significant, except that between sand type and curing period. Higher calcination temperature significantly improves the strength of the mortar. However, the strength of the obtained geopolymer mortars are still significantly lower than that of ordinary Portland cement mortar.

  13. 电煅煤骨料表面生长碳纳米管对高炉炭砖性能的影响%Effect of electrically calcined anthracite aggregates anchored with carbon nanotubes on properties of carbon block for blast furnace

    Institute of Scientific and Technical Information of China (English)

    王同生; 桑绍柏; 李亚伟

    2016-01-01

    利用电煅煤骨料负载催化剂硝酸镍,通过化学气相沉积(CVD)方法在电煅煤骨料表面成功催化生长出碳纳米管(CNTs)。以预处理过的电煅煤骨料为原料制备炭砖试样,借助 X 射线衍射分析、扫描电子隧道显微镜、压汞仪和激光导热仪分析了预处理电煅煤骨料的引入对炭砖在埋碳气氛下经1000℃和1400℃烧后的显微结构和性能的影响。结果表明,将预处理的电煅煤骨料引入到炭砖中,由于促进了试样中β-SiC、AlN 及β-Sialon 相的大量生成,炭砖试样的耐压强度和导热系数得到提高,其微孔特性得到改善。%Carbon nanotubes (CNTs)were successfully synthesized on the surface of electrically cal-cined anthracite (ECA)by chemical vapor deposition (CVD)method with Ni(NO 3 )2 ·6 H 2 O as cata-lyzer.The carbon block samples were prepared subsequently by using those ECA aggregates as the raw material.The effects of pre-treated ECA aggregates on microstructures and properties of carbon block samples heated in coke bed at 1000 ℃ and 1400 ℃ were investigated by XRD,SEM,EDS,mer-cury porosimetry and laser thermal conductivity meter.The results show that when ECA aggregates treated by CVD method are introduced into carbon blocks,the formation of AlN,β-SiC and β-Sialon ceramic phases in great quantities are promoted.As a result,the cold crushing strength,thermal con-ductivity as well as micro-pore properties of carbonized samples can be improved.

  14. 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.

  15. 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.

  16. Activity and Structure of Calcined Coal Gangue

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Coal gangue was activated by means of calcination in seven temperature ranges. Systematic research was made about activation mechanism and structural evolution. Glycerin-ethanol method, SEM, MIP and XRD were used to determine the variation of structure and activation of coal gangue during the calcination.The experimental results show that because of heat treatment in the range of calcination temperature, mineral composition and microstructure of coal gangue are changed. In addition, its activity is improved evidently. The amount of lime absorbed by the sample calcined at 700 C is 2-4 times that by uncalcined coal gangue in the course of hydration. When NaOH is added to coal gangue-lime system, hydration reaction of the system is sped up and the microstructure of hydrating samples of coal gangue is improved.

  17. 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.

  18. 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...

  19. Experimental and modeling study of flash calcination of kaolinite rich clay particles in a gas suspension calciner

    DEFF Research Database (Denmark)

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

    2015-01-01

    Calcination of kaolinite particles under appropriate conditions to produce materials that can replace part of the CO2 intensive clinker is gaining an increasing interest in cement industry worldwide. This paper presents a study of flash calcination of kaolinite rich clay particles in a pilot scale...... gas suspension calciner, with the aim to derive useful guidelines on smart calcination for obtaining products of the best pozzolanic properties. Calcination tests are performed in the calciner under six different operation conditions. The raw feed and the calcined clay samples are all characterized...... experimentally and a mathematical model is also developed to predict the conversion of the clay particles. The model properly accounts for the particle–ambient flow interaction and numerically solves all the processes occurring within the clay particles. The model predictions are compared against...

  20. Calcination-Digestion-Desliming of Phosphorus Ore Bearing Rare Earth

    Institute of Scientific and Technical Information of China (English)

    Zhang Qin; Zhang Jie; Wang Jing; Qiu Yue qin

    2004-01-01

    The recoveries of phosphorus and RE of ore from Zhijin in Guizhou were studied.The influences of the calcination temperature, resident time, the digested time and water volume of the calcinating on concentrate yield by desliming were also investigated by orthogonal design.Appropriate calcination temperature is initial condition that makes carbonate mineral decomposition.The recovery of phosphorus is 83.02% and rare earth is 90.56% in phosphorus concentrate when calcined temperature is 900 ℃, other conditions include: calcined time is 30 min, digestion water volume is 300 ml, digestion time is 20 min.The results show that the pre-treatment of the ore is favorable for the separation and enrichment of rare earth from phosphorus ore, and a process of calcination-digestion-desliming was promised.

  1. Experimental Test Plan for Grouting H-3 Calcine

    Energy Technology Data Exchange (ETDEWEB)

    Alan K. Herbst

    2006-01-01

    Approximately 4400 cubic meters of solid high-level waste called calcine are stored at the Idaho Nuclear Technology and Engineering Center. Under the Idaho Cleanup Project, dual disposal paths are being investigated. The first path includes calcine retrieval, package "as-is", and ship to the Monitored Geological Repository (MGR). The second path involves treatment of the calcine with such methods as vitrification or grouting. This test plan outlines the hot bench scale tests to grout actual calcine and verify that the waste form properties meet the waste acceptance criteria. This is a necessary sequential step in the process of qualifying a new waste form for repository acceptance. The archive H-3 calcine samples at the Contaminated Equipment Maintenance Building attached to New Waste Calcining Facility will be used in these tests at the Remote Analytical Laboratory. The tests are scheduled for the second quarter of fiscal year 2007.

  2. Synthesis and calcinations effects on size analysis of Co{sub 3}O{sub 4} nanospheres and their superparamagnetic behaviors

    Energy Technology Data Exchange (ETDEWEB)

    Anandha Babu, G. [Department of Physics, Alagappa University, Karaikudi 630004, Tamil Nadu (India); Ravi, G., E-mail: gravicrc@gmail.com [Department of Physics, Alagappa University, Karaikudi 630004, Tamil Nadu (India); Hayakawa, Y. [Research Institute of Electronics, Shizuoka University, Hamamatsu 432-8011 (Japan); Kumaresavanji, M. [IFIMUP and IN-Institute of Nanoscience and Nanotechnology, Department of Physics and Astronomy, University of Porto, 687 Rua Campo Alegre, 4169-007 Porto (Portugal)

    2015-02-01

    Co{sub 3}O{sub 4} nanoparticles were synthesized by microwave process using citric acid as a capping agent. Interestingly, when calcination temperature is increased to 600 °C, nanoparticles were formed into nanospheres of about less than 20 nm observed from SEM images. The particles were aggregated into bigger size of about 65 nm when the calcination temperature was increased to 800 °C. The samples calcined at 400 °C and 800 °C show superparamagnetism above the blocking temperature and the existence of small ferromagnetism is observed when Tcalcination temperature of the sample. - Highlights: • Spinel Co{sub 3}O{sub 4} nanoparticles are synthesized by fast and effective microwave route. • Tuning of size and morphology of Co{sub 3}O{sub 4} was investigated by calcination temperatures. • Well defined sphere morphology was achieved for the calcinations of 600 °C. • The prepared Co{sub 3}O{sub 4} was modified into moderate size of less than 20 nm for 600 °C. • The 600 °C calcined sample completely obeys superparamagnetism nature from 5K–300K.

  3. Performance of Cobalt-Based Fischer-Tropsch Synthesis Catalysts Using Dielectric-Barrier Discharge Plasma as an Alternative to Thermal Calcination

    Science.gov (United States)

    Bai, Suli; Huang, Chengdu; Lv, Jing; Li, Zhenhua

    2012-01-01

    Co-based catalysts were prepared by using dielectric-barrier discharge (DBD) plasma as an alternative method to conventional thermal calcination. The characterization results of N2-physisorption, temperature programmed reduction (TPR), transmission electron microscope (TEM), and X-ray diffraction (XRD) indicated that the catalysts prepared by DBD plasma had a higher specific surface area, lower reduction temperature, smaller particle size and higher cobalt dispersion as compared to calcined catalysts. The DBD plasma method can prevent the sintering and aggregation of active particles on the support due to the decreased treatment time (0.5 h) at lower temperature compared to the longer thermal calcination at higher temperature (at 500° C for 5 h). As a result, the catalytic performance of the Fischer-Tropsch synthesis on DBD plasma treated Co/SiO2 catalyst showed an enhanced activity, C5+ selectivity and catalytic stability as compared to the conventional thermal calcined Co/SiO2 catalyst.

  4. 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...

  5. 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.

  6. 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...

  7. 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.

  8. Enhanced Photocatalytic Activity of Powders (P25 via Calcination Treatment

    Directory of Open Access Journals (Sweden)

    Guohong Wang

    2012-01-01

    Full Text Available P25 TiO2 powders were calcined at different temperatures in a muffle furnace in air. The P25 powders before and after calcination treatment were characterized with XRD FTIR, UV-visible diffuse reflectance spectra, SEM, TEM, HRTEM, and N2 adsorption-desorption measurements. The photocatalytic activity was evaluated by the photocatalytic oxidation of methyl orange aqueous solution under UV light irradiation in air. The results showed that calcination treatment obviously influenced the microstructures and photocatalytic activity of the P25 TiO2 powders. The synergistic effect of the phase structure, BET surface area, and crystallinity on the photocatalytic of TiO2 powders (P25 after calcination was investigated. An optimal calcination temperature ( was determined. The photocatalytic activity of TiO2 powders calcined at was nearly 2 times higher than that of the uncalcined P25 TiO2. The highest photocatalytic activities of the calcined samples at for 4 h might be ascribed to the enhancement of anatase crystallization and the optimal mass ratio (ca. 1 : 2 of rutile to anatase.

  9. 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.

  10. 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.

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

    OpenAIRE

    2015-01-01

    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 high...

  12. 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}.

  13. 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.

  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. Adsorption removal of thiocyanate from aqueous solution by calcined hydrotalcite

    Institute of Scientific and Technical Information of China (English)

    LI Yu-jiang; YANG Min; ZHANG Xiao-jin; WU Tao; CAO Nan; WEI Na; BI Yan-jun; WANG Jing

    2006-01-01

    A hydrotalcite with Mg/Al molar ratio 2 was prepared by co-precipitation method and was characterized by XRD,TG/DTA, Zeta potential and BET surface area. The hydrotalcite was calcined at 500℃, with the dehydration from interlayer, the dehydroxilation from the brucite-like layer and the decomposition of carbonate successively, transformed into the mixed oxide type.The removal of thiocyanate from aqueous solution by using the original hydrotalcite and calcined hydrotalcite (HTC-500) was investigated. The results showed that the thiocyanate adsorption capacity of calcined hydrotalcite was much higher than that of the original form. Calcined hydrotalcite was particularly effective at removing thiocyanate, and that the effective range of pH for the thiocyanate removal are between 5.5-10.0. The experimental data of thiocyanate removal fit nicely with Langmuir isotherm, and the saturated adsorption uptake was 96.2 mg SCN-/g HTC-500. The adsorption ofthiocyanate by calcined hydrotalcite follows first-order kinetics. And the intercalation to the structure recovery for calcined hydrotalcite. But the presence of additional anions could affect the adsorption behavior of thiocyanate.

  16. Adsorption removal of thiocyanate from aqueous solution by calcined hydrotalcite.

    Science.gov (United States)

    Li, Yu-Jiang; Yang, Min; Zhang, Xiao-Jin; Wu, Tao; Cao, Nan; Wei, Na; Bi, Yan-Jun; Wang, Jing

    2006-01-01

    A hydrotalcite with Mg/Al molar ratio 2 was prepared by co-precipitation method and was characterized by XRD, TG/DTA, Zeta potential and BET surface area. The hydrotalcite was calcined at 500 degrees C, with the dehydration from interlayer, the dehydroxilation from the brucite-like layer and the decomposition of carbonate successively, transformed into the mixed oxide type. The removal of thiocyanate from aqueous solution by using the original hydrotalcite and calcined hydrotalcite (HTC-500) was investigated. The results showed that the thiocyanate adsorption capacity of calcined hydrotalcite was much higher than that of the original form. Calcined hydrotalcite was particularly effective at removing thiocyanate, and that the effective range of pH for the thiocyanate removal are between 5.5-10.0. The experimental data of thiocyanate removal fit nicely with Langmuir isotherm, and the saturated adsorption uptake was 96.2 mg SCN-/g HTC-500. The adsorption of thiocyanate by calcined hydrotalcite follows first-order kinetics. And the intercalation to the structure recovery for calcined hydrotalcite. But the presence of additional anions could affect the adsorption behavior of thiocyanate.

  17. Structure transition of nano-titania during calcination

    Institute of Scientific and Technical Information of China (English)

    李国华; 王大伟; 徐铸德; 陈卫祥

    2003-01-01

    In order to study the structure transition during calcination, nano-titania powders prepared by hydrolyzing precipitation approach and calcined at 300, 400, 500, 600 and 700 ℃ were characterized by XRD, TEM and electron diffraction(ED), respectively. The results show that titania powders calcined below 500 ℃ are almost composed of anatase, rutile appears below 500 ℃ and its ratio increases gradually with increase of calcin temperature;nano-titania particles are smaller than 40 nm mostly and the dispersion is related to calcining temperature; the interplanar distances of nano-anatase single crystalline change gradually when calcing temperature increases to 500 ℃; so do that of nano-rutile single crystalline when calcining temperature charges from 600 to 700 ℃. The conclusions can be drawn that the temperature of transformation from anatase to rutile is below 500 ℃ and the process carries on gradually. Both inter-planar distances and the structure of nano-titania transform gradually with increasing calcing temperature.

  18. The Kinetics of Calcination of High Calcium Limestone

    Directory of Open Access Journals (Sweden)

    P. C. Okonkwo

    2012-02-01

    Full Text Available The kinetics of calcination of a high calcium type of limestone was studied. Ukpilla limestone found in the central region of Nigeria was studied. The limestone composition shows that the limestone has 51.29% calcium oxide and 41.53% loss on ignition and magnesium oxide content of 2.23%. The following parameters were determined; diffusion coefficient of lime layer, and mass transfer coefficient, conductivity of lime layer and beat transfer coefficient, convective parameter and diffusive parameter for temperatures 9000C, 10000C, 10600C and 10800C. The reaction was found to be limited by mass and heat transfers across the tune layer of the calcining article, theoptimal temperature of calcination was found to be 10600C. Diffusivity and mass transfer coefficient decreases with increase in calcination temperature. The thermal conductivity increases with increase in temperature. The diffusive and convective parameter decreases with increase in temperature. The reactivity of lime calcined at different temperatures were determined. The reactivity of the lime increases with decrease in calcination temperature.

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

    Energy Technology Data Exchange (ETDEWEB)

    Qiu, Xinhong, E-mail: qxinhong@gmail.com [Department of Earth Resources Engineering, Kyushu University,Fukuoka 819-0395 (Japan); Sasaki, Keiko; Takaki, Yu; Hirajima, Tsuyoshi [Department of Earth Resources Engineering, Kyushu University,Fukuoka 819-0395 (Japan); Ideta, Keiko; Miyawaki, Jin [Institute for Materials Chemistry and Engineering, Kyushu University, Kasuga 816-8180 (Japan)

    2015-04-28

    Highlights: • Higher sorption density of borate was observed at higher calcination temperature. • Sorption of borate by Ca-Al-LDH was mainly through DR mechanism. • Removal of borate by Ca-LDH-300 and Ca-LDH-500 were through forming of ettringite. • Boron was mainly adsorbed and intercalated into hydration of Ca-Al-LDH-900. - Abstract: 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 {sup 11}B NMR, {sup 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{sup 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 HBO{sub 3}{sup 2−} into the interlayer, most the LDHs.

  20. 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

  1. Human health risk characterization of petroleum coke calcining facility emissions.

    Science.gov (United States)

    Singh, Davinderjit; Johnson, Giffe T; Harbison, Raymond D

    2015-12-01

    Calcining processes including handling and storage of raw petroleum coke may result in Particulate Matter (PM) and gaseous emissions. Concerns have been raised over the potential association between particulate and aerosol pollution and adverse respiratory health effects including decrements in lung function. This risk characterization evaluated the exposure concentrations of ambient air pollutants including PM10 and gaseous pollutants from a petroleum coke calciner facility. The ambient air pollutant levels were collected through monitors installed at multiple locations in the vicinity of the facility. The measured and modeled particulate levels in ambient air from the calciner facility were compared to standards protective of public health. The results indicated that exposure levels were, on occasions at sites farther from the facility, higher than the public health limit of 150 μg/m(3) 24-h average for PM10. However, the carbon fraction demonstrated that the contribution from the calciner facility was de minimis. Exposure levels of the modeled SO2, CO, NOx and PM10 concentrations were also below public health air quality standards. These results demonstrate that emissions from calcining processes involving petroleum coke, at facilities that are well controlled, are below regulatory standards and are not expected to produce a public health risk.

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. Dissolution kinetics of ulexite prepared under different calcination temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Demirkiran, N.; Kuenkuel, A. [Inonu University, Malatya (Turkey). Faculty of Engineering. Dept. of Chemical Engineering]. E-mail: ndemirkiran@inonu.edu.tr

    2008-10-15

    Ulexite is one of the boron minerals used as a raw material in the production of boron compounds. It contains a substantial amount of hydration water. Using calcination methods, the B{sub 2}O{sub 3} grade of ulexite can be increased. In this study, the effect of calcination temperature on dissolution kinetics of ulexite in ammonium chloride solutions was investigated in a batch reactor employing the parameters of concentration, solid-to-liquid ratio and reaction temperature. It was found that the dissolution rate increased with increasing concentration and reaction temperature and with decreasing solid-to-liquid ratio. The highest dissolution rate was obtained with the sample calcined at 413 K. It was determined that the dissolution rate fit to the second order pseudo-homogeneous model. The activation energy of this dissolution process was found to be 64.3 kJ/mo L. (author)

  7. Morphology, crystal structure and hydration of calcined and modified anhydrite

    Institute of Scientific and Technical Information of China (English)

    Xiao-qing Niu; Ji-chun Chen

    2014-01-01

    The effects of calcination and modification on the morphology (shapes and textures) and crystal structure of anhydrite powders were studied. The results show that, calcination at 100°C causes anhydrite to disintegrate into smaller crystals, accompanied by a slight in-crease in d-spacing. Without calcination and modification, the solidification time and curing time of anhydrite are 15 and 77 h, respectively. After the treatment, however, the solidification time and curing time are shortened significantly to 9.5 and 14 min, respectively. The com-pressive and flexural strengths of hydration products made from the treated anhydrite reach 10.2 and 2.0 MPa, respectively. The much shorter solidification and curing time make it possible to use anhydrite as a building and construction material.

  8. 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.

  9. Corrosion experience in calcination of liquid nuclear waste

    Energy Technology Data Exchange (ETDEWEB)

    Zimmerman, C A

    1980-01-01

    The Waste Calcining Facility (WCF) at the Idaho National Engineering Laboratory became operational in 1963. Since that time, approximately 13,337,137 litres (3,523,375 gallons) of liquid nuclear wastes, generated during the reprocessing of spent nuclear fuel materials, have been reduced to dry granular solids. The volume reduction is about seven or eight gallons of liquid waste to one gallon of dry granular solids. This paper covers some of the corrosion experiences encountered in over fifteen years of operating that calcination facility. 7 figures, 7 tables.

  10. Flash calcination of kaolinite rich clay and impact of process conditions on the quality of the calcines: A way to reduce CO2 footprint from cement industry

    DEFF Research Database (Denmark)

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

    2016-01-01

    deplete metakaolin into unwanted products (e.g., mullite), which limits the use of the calcines as a supplementary cementitious material. With this regard, a dynamic model of flash calcination of kaolinite rich clay particles is developed using gPROMS (general PROcess Modeling System) to predict...... suspension calciner. The model is validated by the experimental data (e.g., the degree of dehydroxylation and the density of the calcines). Based on the model, the impacts of process conditions and feed properties on the quality of the calcination products are thoroughly examined....

  11. 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.

  12. 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

  13. Isotopic variability of mercury in ore, mine-waste calcine, and leachates of mine-waste calcine from areas mined for mercury.

    Science.gov (United States)

    Stetson, Sarah J; Gray, John E; Wanty, Richard B; Macalady, Donald L

    2009-10-01

    The isotopic composition of mercury (Hg) was determined in cinnabar ore, mine-waste calcine (retorted ore), and leachates obtained from water leaching experiments of calcine from two large Hg mining districts in the U.S. This study is the first to report significant mass-dependent Hg isotopic fractionation between cinnabar ore and resultant calcine. Data indicate that delta202Hg values relative to NIST 3133 of calcine (up to 1.52 per thousand) in the Terlingua district, Texas, are as much as 3.24 per thousand heavier than cinnabar (-1.72 per thousand) prior to retorting. In addition, delta202Hg values obtained from leachates of Terlingua district calcines are isotopically similar to, or as much as 1.17 per thousand heavier than associated calcines, most likely due to leaching of soluble, byproduct Hg compounds formed during ore retorting that are a minor component in the calcines. As a result of the large fractionation found between cinnabar and calcine, and because calcine is the dominant source of Hg contamination from the mines studied, delta202Hg values of calcine may be more environmentally important in these mined areas than the primary cinnabar ore. Measurement of the Hg isotopic composition of calcine is necessary when using Hg isotopes for tracing Hg sources from areas mined for Hg, especially mine water runoff.

  14. Analytical comparison between unprepared and calcined magnetitum(Cishi)

    Institute of Scientific and Technical Information of China (English)

    LI Gang; JIN Tongshun; YOU Juan; WANG Lu; WU Qinan

    2007-01-01

    The phases, chemical composition, surface appearance,crystal size,specific surface and thermal behavior of the unprepared and calcined forms of the mineral Magnetitum(Cishi),used as Chinese traditional medicine,were characterized by using X-ray powder diffraction,scan electron microscopy,inductively coupled plasma-atomic emission spectometry(ICP)and thermogravimetrie(TG).The results indicated that after calcination the main phase Fe304 of the calcined Magnetitum(Duan Cishi)remained,while the Fe203 phase disappeared.The contents of the harmful chemical elements Cd and Pb were obviously reduced,while the crystal size increased from 24.5 to 35.7 nm and surface loosened.There were different TG curves for unprepared and calcined Magnetitum(Cishi)samples on heating.The former showed two weight-losing steps(at 367.9-422.1℃ and 568.8-594.1℃),and the latter only one.These results might serve as a base for quality evaluation of Magnetitum (Cishi).

  15. Restart plan for the prototype vertical denitration calciner

    Energy Technology Data Exchange (ETDEWEB)

    SUTTER, C.S.

    1999-09-01

    Testing activities on the Prototype Vertical Denitration Calciner at PFP were suspended in January 1997 due to the hold on fissile material handling in the facility. The Restart Plan will govern the transition of the test program from the completion of the activity based startup review; through equipment checkout and surrogate material runs; to resumption of the testing program and transition to unrestricted testing.

  16. 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.

  17. 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

    A series of sorption of fluoride on calcined magnesite are obtained from thermostatic pH-chemostat and jar test experiments. The fluoride removal is observed not to start instantly, as normal, but after a lag time of up to ½ an hour of contact time. A model for sorption kinetics is developed, bas...

  18. Construction aggregates

    Science.gov (United States)

    Nelson, T.I.; Bolen, W.P.

    2007-01-01

    Construction aggregates, primarily stone, sand and gravel, are recovered from widespread naturally occurring mineral deposits and processed for use primarily in the construction industry. They are mined, crushed, sorted by size and sold loose or combined with portland cement or asphaltic cement to make concrete products to build roads, houses, buildings, and other structures. Much smaller quantities are used in agriculture, cement manufacture, chemical and metallurgical processes, glass production and many other products.

  19. 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.

  20. Pollution and Prevention of Pb during Cement Calcination

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Emission pollution and prevention measures of Pb during cement calcination were discussed. The content of Pb and the variation of composition were explored by means of atomic absorption spectroscopy (AAS) and X-ray diffraction. The results show that a number of Pb emits during cement calcination, F and C1 promote the emission of Pb, and Pb is enriched in kiln dust. The smaller the particle of kiln dust, the higher the content of Pb. When utilizing the raw materials with a high content of Pb, a more efficient dust collector should be used and the kiln dust should be used as the addition of cement. Pb in clinker is enriched in the intermediate phase. The reduction of silica modulus is useful to increase the solidification content of Pb in clinker. The solidification content of Pb in calcium sulphoaluminate mineral is higher than that in calcium aluminate mineral.

  1. Calcined sodium silicate as solid base catalyst for biodiesel production

    Energy Technology Data Exchange (ETDEWEB)

    Guo, Feng; Peng, Zhen-Gang; Dai, Jian-Ying; Xiu, Zhi-Long [Department of Bioscience and Biotechnology, School of Environmental and Biological Science and Technology, Dalian University of Technology, Dalian 116024 (China)

    2010-03-15

    This paper examined the use of calcined sodium silicate as a novel solid base catalyst in the transesterification of soybean oil with methanol. The calcined sodium silicate was characterized by DTA-TG, Hammett indicator method, XRD, SEM, BET, IR and FT-IR. It catalyzed the transesterification of soybean oil to biodiesel with a yield of almost 100% under the following conditions: sodium silicate of 3.0 wt.%, a molar ratio of methanol/oil of 7.5:1, reaction time of 60 min, reaction temperature of 60 C, and stirring rate of 250 rpm. The oil containing 4.0 wt.% water or 2.5 wt.% FFA could also be transesterified by using this catalyst. The catalyst can be reused for at least 5 cycles without loss of activity. (author)

  2. Sorption of aspartic and glutamic aminoacids on calcined hydrotalcite.

    Science.gov (United States)

    Silvério, Fabiano; Dos Reis, Márcio José; Tronto, Jairo; Valim, João Barros

    2013-12-01

    Sorption of aspartic and glutamic aminoacids by regeneration of calcined hydrotalcite is reported. Hydrotalcite was synthesized by coprecipitation and calcined at 773 K. Sorption experiments were performed at 298 K and 310 K, and the results reveal that at low aminoacids equilibrium concentrations, intercalation of hydroxyl anions takes place while at high equilibrium concentrations, the sorption process occur by means re-hydration and aminoacids intercalation of hydrotalcite. The results also suggested that Asp and Glu sorption is a temperature dependent process. The amount of sorbed amino acid decreases as the temperature increase. The effect is more pronounced for Glu sorption probably due to its higher hydrophobic character, which makes the sorption more difficult in comparison with sorption of Asp at higher temperature.

  3. Mathematical modeling of a rotary hearth coke calciner

    Directory of Open Access Journals (Sweden)

    Hilde C. Meisingset

    1995-10-01

    Full Text Available A mathematical model of a rotary hearth coke calciner is developed. The model is based on first principles including the most important dynamic phenomena. The model is a thermodynamic model involving heat and mass transfer and chemical reactions. Fundamental mass and energy balance equations for the coke phase, the gas phase and the lining are formulated. For the gas phase, a stationary model is used. The equations are solved numerically, and simulated temperature profiles are shown in this paper.

  4. Atmospheric pressure plasma assisted calcination of composite submicron fibers

    Science.gov (United States)

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

    2016-08-01

    The plasma assisted calcination of composite organic/inorganic submicron fibers for the preparation of inorganic fibers in submicron scale was studied. Aluminium butoxide/polyvinylpyrrolidone fibers prepared by electrospinning were treated using low-temperature plasma generated by special type of dielectric barrier discharge, so called diffuse coplanar surface barrier discharge (DCSBD) at atmospheric pressure in ambient air, synthetic air, oxygen and nitrogen. Effect of plasma treatment on base polymer removal was investigated by using Attenuated total reflectance - Fourier transform infrared (ATR-FTIR) spectroscopy. Influence of working gas on the base polymer reduction was studied by energy-dispersive X-ray spectroscopy (EDX) and CHNS elemental analysis. Changes in fibers morphology were observed by scanning electron microscopy (SEM). High efficiency of organic template removal without any degradation of fibers was observed after plasma treatment in ambient air. Due to the low-temperature approach and short exposure time, the plasma assisted calcination is a promising alternative to the conventional thermal calcination. Contribution to the topical issue "6th Central European Symposium on Plasma Chemistry (CESPC-6)", edited by Nicolas Gherardi, Ester Marotta and Cristina Paradisi

  5. 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...

  6. ICPP radioactive liquid and calcine waste technologies evaluation. Interim report

    Energy Technology Data Exchange (ETDEWEB)

    Murphy, J.A.; Pincock, L.F.; Christiansen, I.N.

    1994-06-01

    The Department of Energy (DOE) has received spent nuclear fuel (SNF) at the Idaho Chemical Processing Plant (ICPP) for interim storage since 1951 and reprocessing since 1953. Until recently, the major activity of the ICPP has been the reprocessing of SNF to recover fissile uranium; however, changing world events have raised questions concerning the need to recover and recycle this material. In April 1992, DOE chose to discontinue reprocessing SNF for uranium recovery and shifted its focus toward the management and disposition of radioactive wastes accumulated through reprocessing activities. Currently, 1.8 million gallons of radioactive liquid wastes (1.5 million gallons of radioactive sodium-bearing liquid wastes and 0.3 million gallons of high-level liquid waste) and 3,800 cubic meters (m{sup 3}) of calcine waste are in inventory at the ICPP. Legal drivers and agreements exist obligating the INEL to develop, demonstrate, and implement technologies for safe and environmentally sound treatment and interim storage of radioactive liquid and calcine waste. Candidate treatment processes and waste forms are being evaluated using the Technology Evaluation and Analysis Methodology (TEAM) Model. This process allows decision makers to (1) identify optimum radioactive waste treatment and disposal form alternatives; (2) assess tradeoffs between various optimization criteria; (3) identify uncertainties in performance parameters; and (4) focus development efforts on options that best satisfy stakeholder concerns. The Systems Analysis technology evaluation presented in this document supports the DOE in selecting the most effective radioactive liquid and calcine waste management plan to implement in compliance with established regulations, court orders, and agreements.

  7. 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.

  8. Performance of Cobalt-Based Fischer-Tropsch Synthesis Catalysts Using Dielectric-Barrier Discharge Plasma as an Alternative to Thermal Calcination%Performance of Cobalt-Based Fischer-Tropsch Synthesis Catalysts Using Dielectric-Barrier Discharge Plasma as an Alternative to Thermal Calcination

    Institute of Scientific and Technical Information of China (English)

    白素丽; 黄承都; 吕静; 李振花

    2012-01-01

    Co-based catalysts were prepared by using dielectric-barrier discharge (DBD) plasma as an alternative method to conventional thermal calcination. The characterization results of N2-physisorption, temperature programmed reduction (TPR), transmission electron microscope (TEM), and X-ray diffraction (XRD) indicated that the catalysts prepared by DBD plasma had a higher specific surface area, lower reduction temperature, smaller particle size and higher cobalt dispersion as compared to calcined catalysts. The DBD plasma method can prevent the sintering and aggregation of active particles on the support due to the decreased treatment time (0.5 h) at lower temperature compared to the longer thermal calcination at higher temperature (at 500~C for 5 h). As a result, the catalytic performance of the Fischer-Tropsch synthesis on DBD plasma treated Co/Si02 catalyst showed an enhanced activity, C5+ selectivity and catalytic stability as compared to the conventional thermal calcined Co/SiO2 catalyst.

  9. Nano-porous pottery using calcined waste sediment from tap water production as an additive.

    Science.gov (United States)

    Sangsuk, Supin; Khunthon, Srichalai; Nilpairach, Siriphan

    2010-10-01

    A suspension of sediment from a lagoon in a tap water production plant was collected for this experiment. The suspension was spray dried and calcined at 700 °C for 1 h. After calcining, 30 wt.% of the sediment were mixed with pottery clay. Samples with and without calcined sediment were sintered at 900, 1000 and 1100 °C. The results show that calcined sediment can be used as an additive in pottery clay. The samples with calcined sediment show higher porosity, water absorption and flexural strength, especially for 900 and 1000 °C. At 900 °C, samples with calcined sediment show a porosity of 50% with an average pore size of 68 nm, water absorption of 31% and flexural strength of 12.61 MPa.

  10. Effects of calcination temperature on the pore size and wall crystalline structure of mesoporous alumina.

    Science.gov (United States)

    Sun, Zhong-Xi; Zheng, Ting-Ting; Bo, Qi-Bing; Du, Miao; Forsling, Willis

    2008-03-01

    In this paper, mesoporous alumina with different pore sizes and wall crystalline structures was synthesized at calcination temperatures over 550 degrees C. The characterization of the samples calcined at 550, 800, 1100, and 1300 degrees C, respectively, was performed using TEM, XRD, FTIR, TG/DTA, and N2 adsorption/desorption techniques. The correlation between pore size and wall crystalline structure on calcination temperature was systematically investigated.

  11. 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.

  12. Non-Isothermal Calcination Kinetics of Phosphate Rock

    Directory of Open Access Journals (Sweden)

    Hatice Bayrakçeken

    2014-07-01

    Full Text Available The kinetics of thermal decomposition of the phosphate rock was studied by means of thermal analysis techniques (TG/DTG in inert nitrogen (N2 atmosphere at heating rates of 2, 5, 10, and 20 K min-1. TG and DTG measurements indicated that calcination of the phosphate rock has single-stage degradation in between 873-1173 K. Kissinger–Akahira–Sunose (KAS and Flynn-Wall-Ozawa (FWO isoconversional methods were applied to the data obtained from TG and DTG curves and the activation energies were found as 170 ve 187 kJmol-1, respectively. It was determined that the thermal decomposition mechanism of phosphate rock was occurred via nucleation and growth (-ln(1-α2/3 mechanism. Pre-exponentional factor (lnA was determined as 20.47.

  13. Ignition Dynamic Parameters for Coke in Cement Calciners

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The mathematical ignition model was established and researches of ignition dynamic parameters for coke in some typical coal samples from cement plants was carried out according to circumstances of coal combusted in cement plants.In order to get the ignitioin temperature Tpi of carbon particles more accurately,the temperature rising experimental method was used and the actual heating circumstances for pulverized coal in calciners(in cement plants)were also considered.With this method,the accurate determination of the ignition temperature of coke in coal was achieved,so as to get some ignition dynamic parameters.These research results provide a theoretical basis for investigating coal ignition characteristics more scientifically and more accurately.

  14. 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...... data reveal that the crystallite size increases significantly, and the SANS and adsorption isotherm studies suggest that the specific surface area decreases by a factor of 5–6. The TEM images show that the particles are sintered into larger agglomerates, but they also show that parts of the porous...

  15. STUDY ON HIGH ACID LEACHING REACTIVE CALCINED KAOLIN

    Institute of Scientific and Technical Information of China (English)

    1999-01-01

    Leaching experiments on metakaolin show that the final Al extraction ratio reached in a batch reaction is strikingly influenced by the inferior pore structure geometry of the metakaolin pellets. By calcining kaolin particles adhered in low humidity state,a variety of metakaolin pellet,inside which a large openings structure developed,has been prepared. The structure remarkably benefits leachant ion transference,so,the variety has high acid leaching reactivity,even coarse as the pellets are,its aluminum extracted ratio still has a linear relationship with leaching time,and the leaching kinetics is maintained zero order up to a significant conversion degree. A revised Pellet-Particle Model has been developed to interpret the structure influence on Al extraction ratio.

  16. 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.

  17. Processing of Spent Ion Exchange Resins in a Rotary Calciner - 12212

    Energy Technology Data Exchange (ETDEWEB)

    Kascheev, Vladimir; Musatov, Nikolay [Joint Stock Company ' A.A. Bochvar High-Technology Scientific Research Institute of Inorganic Materials' (VNIINM), Rogova st., 5A (Russian Federation)

    2012-07-01

    Processing Russian nuclear ion exchange resin KU-2 using a 'Rotary' calciner was conducted. The resulting product is a dry free flowing powder (moisture content 3 wt.%, Angle of repose of ≅ 20 deg.). Compared with the original exchange resin the volume of the final product is about 3 times less.. Rotary calciner product can be stored in metal drums or in special reinforced concrete cubicles. After thermal treatment in a rotary calciner, the spent resin product can be solidified in cement yielding the following attributes: - The cemented waste is only a 35% increase over the volume of powder product; - The volume of cement calciner product is almost 9 times less (8.7) than the volume of cement solidified resin; - The mechanical strength of cemented calciner product meets the radioactive waste regulations in Russia. (authors)

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

    DEFF Research Database (Denmark)

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

    2002-01-01

    Simulations with a heterogeneous model of an in-line low-NOx calciner, based on non-isothermal diffusion-reaction models for char combustion and limestone calcination combined with a kinetic model for NO formation and reduction, are reported. The analysis shows that the most important hydrodynamic...... parameter is the mixing rate of preheated combustion air into the sub-stoichiometric suspension leaving the reducing zone and the most important combustion parameter is the char reactivity. Also, the calcination rate modifies very much the temperature in the calciner, char and limestone conversion...... 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...

  19. 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.

  20. Calcination/dissolution chemistry development Fiscal year 1995

    Energy Technology Data Exchange (ETDEWEB)

    Delegard, C.H.

    1995-09-01

    The task {open_quotes}IPC Liaison and Chemistry of Thermal Reconstitution{close_quotes} is a $300,000 program that was conducted in Fiscal Year (FY) 1995 with U.S. Department of Energy (DOE) Office of Research and Development (EM-53) Efficient Separations and Processing Crosscutting Program supported under technical task plan (TTP) RL4-3-20-04. The principal investigator was Cal Delegard of the Westinghouse Hanford Company (WHC). The task encompassed the following two subtasks related to the chemistry of alkaline Hanford Site tank waste: (1) Technical Liaison with the Institute of Physical Chemistry of the Russian Academy of Science (IPC/RAS) and its research into the chemistry of transuranic elements (TRU) and technetium (Tc) in alkaline media. (2) Laboratory investigation of the chemistry of calcination/dissolution (C/D) (or thermal reconstitution) as an alternative to the present reference Hanford Site tank waste pretreatment flowsheet, Enhanced Sludge Washing (ESW). This report fulfills the milestone for the C/D subtask to {open_quotes}Provide End-of-Year Report on C/D Laboratory Test Results{close_quotes} due 30 September 1995. A companion report, fulfilling the milestone to provide an end-of-year report on the IPC/RAS liaison, also has been prepared.

  1. Immobilization of Penicillin G Acylase on Calcined Layered Double Hydroxides

    Institute of Scientific and Technical Information of China (English)

    REN Ling-ling; HE Jing; Evans D. G.; DUAN Xue

    2003-01-01

    A hydrotalcite-like Mg2+/Al3+ layered double hydroxide(LDH) material was prepared by means of a modified coprecipitation method involving a rapid mixing step followed by a separate aging process. LDH calcined at 500 ℃, denoted as CLDH, was characterized by XRD, IR and BET surface area measurements. CLDH has a poor crystalline MgO-like structure with a high surface area and porosity. CLDH was used as a support for the immobilization of penicillin G acylase(PGA). The effect of varying the immobilization conditions, such as pH, contact time and the ratio of enzyme to support, on the activity of the immobilized enzyme in the hydrolysis of penicillin G has been studied. It was found that the activity of the immobilized enzyme decreased slightly with decreasing pH and reached a maximum after a contact time of 24 h. The activity of the immobilized enzyme increased with increasing the ratio of enzyme to support. It was found that the adsorption of PGA inhibited the expected reaction of CLDH with an aqueous medium to regenerate a LDH phase. Its original activity(36%) after 15 cycles of reuse of the immobilized enzyme was retained, but no further loss in the activity was observed.

  2. 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.

  3. Effect of Heat Treatment Temperature on Properties of Chinese Calcined Flint Clay Based Plastic Refractories

    Institute of Scientific and Technical Information of China (English)

    ZHANG Wei; DAI Wenyong; YU Xinfeng; LI Liang

    2009-01-01

    Effects of different heat treatment temperatures on properties of Chinese calcined flint clay based plastic refractories were investigated using Chinese calcined flint clay as starting material,aluminum sulfate and fireclay as binding system.The results showed that with temperature rising,Chinese calcined flint clay based plastic refractories shrinked firstly and then expanded.The modulus of rupture (MOR) and the cold crushing strength (CCS) increased firstly and then decreased from 110 ℃ to 600 ℃,then increased obviously.Thermal expansion coefficient increased from 110 ℃ to 760 ℃,decreased from 760 ℃ to 1 300 ℃,and increased from 1 300 ℃ to 1 500 ℃.

  4. 煤矸石煅烧实验研究%Coal Gangue Calcined Experimental Study

    Institute of Scientific and Technical Information of China (English)

    李宏星

    2014-01-01

    This paper discusses the three major factors affecting coal gangue calcined whitening and structure changes before and after calcination,points out that the calcination process selection is the ket section,but the factors is associated,mutual penetration,should not be ignored.%论述了影响煤矸石煅烧增白的三大因素及煅烧前后的结构变化,指出煅烧工艺选择是关键,但各因素又是相关连、互相渗透的,都不应忽视。

  5. Mechanism of Calcined Phosphogypsum for the Volume Change of Blended Cement

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    The paper describes an investigation into the volume change of cement mortar specimen at the three kinds of different curing schedules including 20℃ and 5% Na2SO4 solution curing, tap water standard curing, 50% RH curing for 90 days. The testing results of hydration heat, chemical shrinking and XRD prove that calcined phosphogypsum has evident excitation effect on the activity of high calcium ash and steel slag. Simultaneously, calcined phosphogypsum has the function of decreasing volume shrinkage to blended cement possessing steel slag and high calcium ash. In sulfate curing, calcined phosphogypsum can avoid the phenomenon of protrude apex of the blended cement.

  6. Thermodynamic Modeling of the Chemical Composition of Calcine at the Idaho Nuclear Technology and Engineering Center

    Energy Technology Data Exchange (ETDEWEB)

    C. M. Frazee; J. D. Christian

    2004-02-01

    To send calcine produced at Idaho National Engineering and Environmental Laboratory to the Yucca Mountain Project for disposal, characterization information will be required. To sample calcine from its existing storage location would require extensive personnel exposure. Sufficient analyses of the chemical composition of the calcine would be extremely difficult and very expensive. In support of characterization development, the chemical composition of calcine from Bin 3 of Calcine Solid Storage Facility II was thermodynamic modeled. This calcine was produced in the Waste Calcination Facility during its second processing campaign, operating with indirect heating at 400 C and 0.744 bar (0.734 atm) during processing of aluminum high-level liquid waste (first cycle extraction raffinate from reprocessing aluminum-clad fuels) from tanks WM-180 and -182 from December 27, 1966 through August 26, 1967. The current modeling effort documents the input compositional data (liquid feed and calciner off-gas) for Batches 300 - 620 and a methodology for estimating the calcine chemical composition. The results, along with assumptions and limitations of the thermodynamic calculations, will serve as a basis for benchmarking subsequent calculations. This will be done by comparing the predictions against extensive analytical results that are currently being obtained on representative samples of the modeled calcine. A commercial free-energy minimization program and database, HSC 5.1, was used to perform the thermodynamic calculations. Currently available experimental data and process information on the calcine were used to make judgments about specific phases and compounds to include and eliminate in the thermodynamic calculations. Some off-gas species were eliminated based on kinetics restrictions evidenced by experimental data and other estimates, and some calcine components and off-gas compounds were eliminated as improbable species (unreliable thermodynamic data). The current Yucca

  7. 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 aggrega

  8. 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.

  9. Decomposition of bastnasite and monazite mixed rare earth minerals calcined byalkali liquid

    Institute of Scientific and Technical Information of China (English)

    XU Yanhui; LIU Haijiao; MENG Zhijun; CUI Jianguo; ZHAO Wenyi; LI Liangcai

    2012-01-01

    The process of decomposion of the bastnasite and monazite rare earth concentrates by alkali solutions was investigated.The mixed slurries of the rare earth concentrates and the alkali solutions were calcined at different temperatures in a rotary tubular electric furnace.The effects of calcination temperature on the decomposing ratio of rare earth,the oxidation ratio of cerium,the stripping of fluorine and phosphorous after calcinations,and the adaptability of the process to the mixed rare earth concentrates of different grade were studied.The results showed that the decomposition ratio of rare earth and the oxidation ratio of cerium could reach 95.8% and 93.7%,respectively,while the calcinating temperature was above 300 ℃.

  10. 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 ancillary equipment were previously tested with non-radioactive chemicals to demonstrate operability.

  11. Kinetics Analysis on Mixing Calcination Process of Fly Ash and Ammonium Sulfate

    Institute of Scientific and Technical Information of China (English)

    Peng Wang; Laishi Li; Dezhou Wei

    2014-01-01

    abstract The further development of the extraction of alumina that is produced in the calcination process of ammonium sulfate mixed with fly ash was limited because of the lack of systematic theoretical study. In order to aggrandize the research of the calcination process, the kinetics and reaction mechanism of the calcinations were studied. The result suggests that there are two stages in the calcination process, and the alumina extraction rate increases swiftly in the initial stage, but slows down increasing in the later stage. The apparent activation energy of the initial and later stages equals to 13.31 and 35.65 kJ·mol-1, respectively. In the initial stage, ammonium sulfate reacts directly with mullite in the fly ash to form ammonium aluminum sulfate, while in the later stage, alumi-num sulfate is formed by the reaction between ammonium aluminum sulfate and ammonium sulfate.

  12. Bovine Calcined Bone for the Repair of Radial Defect in a Rabbit Model

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    In order to investigate the bovine calcined bone's ability of repairing segmental bone defect and seek a new artificial bone substitute material, the bovine calcined bone (450℃,32 h) was implanted into the 10-mm middle radial defect of rabbits with tricalcium phosphate ceramics as the control. By using the methods of histology, radiology and biomechanics their osteogenic ability were measured. It was found that the bovine calcined bone's ability of repairing bone defect was better than that of tricalcium phosphate ceramics. The histological Nilsson′s scores at 3rd, 5th, 9th week after operation were significantly increased (P<0.01). At 12th week after operation the bending strength of radius in experimental group was much higher than that of control group and turned normal. It was suggested that bovine calcined bone is an ideal artificial bone substitute material with good ability of repairing segmental bone defect and some degree of mechanical strength.

  13. Synthesis of Dy2O3 nanoparticles via hydroxide precipitation:effect of calcination temperature

    Institute of Scientific and Technical Information of China (English)

    Bahaa M. Abu-Zied; Abdullah M. Asiri

    2014-01-01

    This work described the preparation of dysprosium oxide, Dy2O3, nanoparticles using the homogeneous precipitation method. Dy3+ions were precipitated using NaOH solution. The obtained product was filtered, dried, and then calcined for 1 h at the temperature range of 300-700 °C in static air. The calcination temperature of the Dy-precursor was chosen based on its decomposi-tion as indicated by the TGA analysis. The crystalline structure and surface morphology of the calcined solids were studied by X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM) and X-ray pho-toelectron spectroscopy (XPS). The obtained results revealed that Dy2O3 with crystallites size of 11-21 nm was formed at 500 °C. Such value increased to 25-37 nm for the sample calcined at 700 °C.

  14. Effect of Calcination Conditions on the Performance of Co-precipitation Catalyst

    Directory of Open Access Journals (Sweden)

    Lin Kai

    2016-01-01

    Full Text Available The Fe-Co-Ce composite catalysts were prepared by co-precipitation method, and the effect of calcination temperature and calcination time on the performances of the Fe-Co-Ce composite catalysts were investigated. The results indicated that the optimum calcination temperature and calcination time of the Fe-Co-Ce composite catalysts were 450 °C and 7 h, respectively. Using the catalysts which prepared under the optimum calcination conditions catalytic wet oxidation of methyl orange simulated wastewater, after 90 min, the COD, COD removal rate, absorbance, decolorization rate and pH of the methyl orange simulated wastewater were 737.7, 70.5%, 0.348, 95.3%, and 5.31, respectively. According to the analyses of the SEM, FTIR, and TG-DTA curves, the components of the catalysts which prepared under the optimum calcination conditions distributed evenly, and the chemical compositions of the catalysts including C-O, -OH, and H-O-H, showing a good thermal stability.

  15. 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.

  16. 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.

  17. 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.

  18. 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.

  19. 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.

  20. 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.

  1. Influence of Light Calcining Hydration of Magnesite on MgO Sintering

    Institute of Scientific and Technical Information of China (English)

    LI Huan; YU Jingkun; KUANG Shibo

    2009-01-01

    Sintered magnesia clinker (also called sintered MgO ) was prepared with Mg(OH)2 (prepared by light calcining hydration of magnesite) and magnesite as starting materials, respectively, by the technical process : light calcining (850 ℃ 1 h )→grinding → molding →firing ( 1 600 ℃ 3 h ). The morphology and struc-ture of light calcined MgO powders prepared with mag-nesite or Mg(OH)2 were analyzed by XRD, SEM and FT-IR. The sinterability and microstructure of sintered magnesia prepared with magnesite or Mg(OH)2 were re-searched. The results showed that: (1) light calcined MgO powders prepared with magnesite or Mg (OH)2 were both face-centered cubic structure. The light cal-cined MgO prepared with magnesitehad the residual of functional group CO32- , and that prepared with Mg (OH)2 didn't have CO32-, and was easy to break, which reduced the grinding time. (2) Because of the high activity of the light calcined MgO prepared with Mg(OH)2 and the catalysis of the water residual in the decomposing process of Mg(OH)2, the apparent porosity of sintered magnesia decreased to 0.6% from 2.0% of before hydration, closed porosity decreased to 2.8% from 6.1%, and bulk density increased to 3.46 g·cm-3 from 3.29 g·cm-3

  2. 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.

  3. Synthesis and characterization of ZSM-5 and calcined kaolin evaluation using the content of structure-directing; Sintese e caracterizacao da zeolita ZSM-5 utilizando caulim calcinado e avaliacao do teor de direcionador de estrutura

    Energy Technology Data Exchange (ETDEWEB)

    Rodrigues, J.J.; Silva, V.J. da; Rodrigues, M.G.F., E-mail: jocielys@yahoo.com.br [Universidade Federal de Campina Grande (LABNOV/UAEQ/UFCG), PB (Brazil). Unidade Academica de Engenharia Quimica. Lab. de Desenvolvimento de Novos Materiais

    2012-07-01

    This study aims to evaluate the effect of the structure-directing content, tetrapropylammonium bromide, on the structural and morphological characteristics of ZSM-5 zeolite obtained using calcined kaolin as silicon and aluminum. The samples were characterized by XRD, EDX, SEM and Physics Adsorption N{sub 2}. Trough X ray diffraction patterns was possible to observed the formation of the structure of ZSM-5 with intense peaks and well-defined characteristic of crystalline. The micrographs showed that the samples consist of agglomerates and/or aggregates of particles characteristic of the MFI structure typical of ZSM-5 zeolite. And through the adsorption-desorption isotherms physical N2 was possible to observe that the samples show hysteresis type I typical of microporous materials with specific surface areas of 218 and 222 m{sup 2}/g. Therefore, the use of calcined kaolin to obtain ZSM-5 zeolite was effective. (author)

  4. Design and performance of a full-scale spray calciner for nonradioactive high-level-waste-vitrification studies

    Energy Technology Data Exchange (ETDEWEB)

    Miller, F.A.

    1981-06-01

    In the spray calcination process, liquid waste is spray-dried in a heated-wall spray dryer (termed a spray calciner), and then it may be combined in solid form with a glass-forming frit. This mixture is then melted in a continuous ceramic melter or in an in-can melter. Several sizes of spray calciners have been tested at PNL- laboratory scale, pilot scale and full scale. Summarized here is the experience gained during the operation of PNL's full-scale spray calciner, which has solidified approx. 38,000 L of simulated acid wastes and approx. 352,000 L of simulated neutralized wastes in 1830 h of processing time. Operating principles, operating experience, design aspects, and system descriptions of a full-scale spray calciner are discussed. Individual test run summaries are given in Appendix A. Appendices B and C are studies made by Bechtel Inc., under contract by PNL. These studies concern, respectively, feed systems for the spray calciner process and a spray calciner vibration analysis. Appendix D is a detailed structural analysis made at PNL of the spray calciner. These appendices are included in the report to provide a complete description of the spray calciner and to include all major studies made concerning PNL's full-scale spray calciner.

  5. 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...

  6. Aggregations in Flatworms.

    Science.gov (United States)

    Liffen, C. L.; Hunter, M.

    1980-01-01

    Described is a school project to investigate aggregations in flatworms which may be influenced by light intensity, temperature, and some form of chemical stimulus released by already aggregating flatworms. Such investigations could be adopted to suit many educational levels of science laboratory activities. (DS)

  7. 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

  8. 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.

  9. Influence of acid leaching and calcination on iron removal of coal kaolin

    Institute of Scientific and Technical Information of China (English)

    Pei-wang Zhu; Wei-qiang Zeng; Xiu-lin Xu; Le-ming Cheng; Xiao Jiang; Zheng-lun Shi

    2014-01-01

    Calcination and acid leaching of coal kaolin were studied to determine an effective and economical preparation method of calcined kaolin. Thermogravimetric-differential thermal analysis (TG-DTA) and X-ray diffraction (XRD) demonstrated that 900°C was the suitable temperature for the calcination. Leaching tests showed that hydrochloric acid was more effective for iron dissolution from raw coal kaolin (RCK), whereas oxalic acid was more effective on iron dissolution from calcined coal kaolin (CCK). The iron dissolution from CCK was 28.78wt%, which is far less effective than the 54.86wt% of RCK under their respective optimal conditions. Through analysis by using Mössbauer spectroscopy, it is detected that nearly all of the structural ferrous ions in RCK were removed by hydrochloric acid. However, iron sites in CCK changed slightly by oxalic acid leaching because nearly all ferrous ions were transformed into ferric species after firing at 900°C. It can be concluded that it is difficult to remove the structural ferric ions and ferric oxides evolved from the structural ferrous ions. Thus, iron removal by acids should be conducted prior to calcination.

  10. Effect of Calcined Temperature on the Solubility of Trace Elements from Manifanshi

    Institute of Scientific and Technical Information of China (English)

    HONG Hanlie; TIE Liyun; BIAN Qiujuan; ZHOU Yong

    2006-01-01

    A medical stone manifanshi were researched by using polarized light microscopy, X-ray diffraction (XRD), and inductively coupled plasma atomic emission spectrometry (ICP-AES) methods. The XRD pattern of the raw Manifanshi indicates that it is dominantly composed of plagioclase, orthoclase, quartz, and that of the calcined Manifanshi at 1000 ℃ shows that the distortion of crystal structure in both plagioclase and orthoclase takes place at the calcined temperature. The polarized light microscopy observation suggests that the Manifanshi is naturally weathered monzo-granite porphyry. Chemical analyses reveal that the Manifanshi contains a number of healthful trace elements and rare toxic trace elements, therefore, it is a high quality Manifanshi. The solubility of trace elements was determined by measuring the concentration of trace elements from Manifanshi calcined under varying temperature conditions by ICP method, the results suggest that the calcined product at 1000 ℃ shows the ideal result in ionic concentrations and dissolution rate of trace elements in water, which is contributed to the distortion of the crystal structure of feldspar at the calcined temperature.

  11. 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.

  12. Effects of nanosized metallic palladium loading and calcination on characteristics of composite silica

    Institute of Scientific and Technical Information of China (English)

    吴玉程; 吴侠; 李广海; 张立德

    2003-01-01

    In order to investigate the effects of nanosized metallic palladium loading and calcination on the characteristics of composite silica,the silica was prepared by sol-gel technique,leading to an amorphous solid with mesoporosity,and the pore size distribution is narrow,centered at 3-5 nm.The composite silica was formed by impregnating palladium precursor into the porous network with sequel calcination in hydrogen.The results show that the nanosized palladium as guest phase in the composite silica is subjected to the mesoporous structure and calcination,resulting in the changes of optical adsorption that red-shifted to higher wavelength with the palladium loading and the heating temperature.The tailoring of the optical properties can be ascribed to the effect of the nanosized metal particles and interactions occurred between palladium and silica.

  13. Ce - promoted catalyst from hydrotalcites for CO2 reforming of methane: calcination temperature effect

    Directory of Open Access Journals (Sweden)

    Carlos Enrique Daza

    2012-01-01

    Full Text Available Ce-promoted Ni-catalysts from hydrotalcites were obtained. The effect of calcination temperature on the chemical and physical properties of the catalysts was studied. Several techniques were used to determine the chemical and physical characteristics of oxides. The apparent activation energies of reduction were determined. Catalytic experiments at 48 L g-1h-1 without pre-reduction in CO2 reforming of methane were performed. The spinel-like phase in these oxides was only formed at 1000 ºC. The reduction of Ni2+ in the oxides was clearly affected by the calcination temperature which was correlated with catalytic performance. The catalyst calcined at 700 ºC showed the greatest activity.

  14. 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.

  15. Mensuration of microstructure multi-fractal spectra of calcined limestone particle surfaces

    Institute of Scientific and Technical Information of China (English)

    Jianyu Shang; Songling Wang; Chunbo Wang; Chunchang Song

    2010-01-01

    The microstructure of the surface of a calcined limestone particle is multi-fractal.We develop an analytic method that surveys the boundary curve multi-fractal dimensions with SEM,gets a three-dimensional surface structure α-f(α)curve via zero-sets,and finally calculates the multi-fractal spectrum values of the particle surface's microstructural topography.After analyzing two spectra from limestone particles calcined at 850 ℃ and 900 ℃,it was shown that the microstructural topographies of the surfaces of calcined limestone multi-particle system have some degree of self-similarity.This mensuration method is proposed to describe the multi-fractal characteristics of a micro-scale particle's surface topography.

  16. 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.

  17. Heavy metal removal from acid mine drainage by calcined eggshell and microalgae hybrid system.

    Science.gov (United States)

    Choi, Hee-Jeong; Lee, Seung-Mok

    2015-09-01

    This study investigates the use of calcined eggshells and microalgae for the removal of heavy metals from acid mine drainage (AMD) and the simultaneous enhancement of biomass productivity. The experiment was conducted over a period of 6 days in a hybrid system containing calcined eggshells and the microalgae Chlorella vulgaris. The results show that the biomass productivity increased to ~8.04 times its initial concentration of 0.367 g/L as measured by an optical panel photobioreactor (OPPBR) and had a light transmittance of 95 % at a depth of 305 mm. On the other hand, the simultaneous percent removal of Fe, Cu, Zn, Mn, As, and Cd from the AMD effluent was found to be 99.47 to 100 %. These results indicate that the hybrid system with calcined eggshells and microalgae was highly effective for heavy metal removal in the AMD.

  18. Effect of Different Calcination Duration on Physicochemical Properties of Vanadium Phosphate Catalysts

    Directory of Open Access Journals (Sweden)

    Yun Hin Taufiq-Yap

    2012-01-01

    Full Text Available Vanadium phosphate catalysts have been prepared by calcining VOHPO44·0.5H2O which were prepared via two methods i.e. organic (VPO method and dihydrate (VPD method routes for different duration under anaerobic atmosphere. Increasing the calcinations duration led to a decrease in total surface area. It is also promote the formation of V5+ phase in the catalysts. Scanning electron microscopy clearly revealed that the morphologies of all catalysts composed of plate-like crystallites that were arranged into the characteristic of rosette cluster. However, by increasing the pretreatment duration in an inert environment, the rosette-shape of the clusters which normally obtained in reaction condition was collapsed. Prolong the duration of N2 calcination also resulted in an increment in the amount of oxygen desorbed (from O2-TPD and removed (obtained from H2-TPR.

  19. Effects of Calcination Condition on Porous Reduced Titanium Oxides and Oxynitrides via Preceramic Polymer Route

    Energy Technology Data Exchange (ETDEWEB)

    Hasegawa, George; Sato, Tatsuya; Kanamori, Kazuyoshi; Sun, Cheng-Jun; Ren, Yang; Kobayashi, Yoji; Kageyama, Hiroshi; Abe, Takeshi; Nakanishi, Kazuki

    2015-03-16

    The preceramic polymer route from titanium-based inorganic-organic hybrid networks provides electro conductive N-doped reduced titanium oxides (TinO2n–1) and titanium oxynitrides (TiOxNy) with a monolithic shape as well as well-defined porous structure. This methodology demonstrates advantageously lower temperature of crystal phase transition compared to the reduction of TiO2 by carbon or H2. In this study, effects of calcination condition on various features of the products have been explored by adopting three different atmospheric conditions and varying the calcination temperature. The detailed crystallographic and elemental analyses disclose the distinguished difference in phase transition behavior with respect to calcination atmosphere. Correlation between the crystallization and nitridation behaviors, porous properties and electric conductivities in the final products has been discussed.

  20. Protein aggregate myopathies

    Directory of Open Access Journals (Sweden)

    Sharma M

    2005-01-01

    Full Text Available Protein aggregate myopathies (PAM are an emerging group of muscle diseases characterized by structural abnormalities. Protein aggregate myopathies are marked by the aggregation of intrinsic proteins within muscle fibers and fall into four major groups or conditions: (1 desmin-related myopathies (DRM that include desminopathies, a-B crystallinopathies, selenoproteinopathies caused by mutations in the, a-B crystallin and selenoprotein N1 genes, (2 hereditary inclusion body myopathies, several of which have been linked to different chromosomal gene loci, but with as yet unidentified protein product, (3 actinopathies marked by mutations in the sarcomeric ACTA1 gene, and (4 myosinopathy marked by a mutation in the MYH-7 gene. While PAM forms 1 and 2 are probably based on impaired extralysosomal protein degradation, resulting in the accumulation of numerous and diverse proteins (in familial types in addition to respective mutant proteins, PAM forms 3 and 4 may represent anabolic or developmental defects because of preservation of sarcomeres outside of the actin and myosin aggregates and dearth or absence of other proteins in these actin or myosin aggregates, respectively. The pathogenetic principles governing protein aggregation within muscle fibers and subsequent structural sarcomeres are still largely unknown in both the putative catabolic and anabolic forms of PAM. Presence of inclusions and their protein composition in other congenital myopathies such as reducing bodies, cylindrical spirals, tubular aggregates and others await clarification. The hitherto described PAMs were first identified by immunohistochemistry of proteins and subsequently by molecular analysis of their genes.

  1. Charged Dust Aggregate Interactions

    Science.gov (United States)

    Matthews, Lorin; Hyde, Truell

    2015-11-01

    A proper understanding of the behavior of dust particle aggregates immersed in a complex plasma first requires a knowledge of the basic properties of the system. Among the most important of these are the net electrostatic charge and higher multipole moments on the dust aggregate as well as the manner in which the aggregate interacts with the local electrostatic fields. The formation of elongated, fractal-like aggregates levitating in the sheath electric field of a weakly ionized RF generated plasma discharge has recently been observed experimentally. The resulting data has shown that as aggregates approach one another, they can both accelerate and rotate. At equilibrium, aggregates are observed to levitate with regular spacing, rotating about their long axis aligned parallel to the sheath electric field. Since gas drag tends to slow any such rotation, energy must be constantly fed into the system in order to sustain it. A numerical model designed to analyze this motion provides both the electrostatic charge and higher multipole moments of the aggregate while including the forces due to thermophoresis, neutral gas drag, and the ion wakefield. This model will be used to investigate the ambient conditions leading to the observed interactions. This research is funded by NSF Grant 1414523.

  2. 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...

  3. 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.

  4. Study of as-synthesized and calcined hydrocalumites as possible antacid agents

    Indian Academy of Sciences (India)

    Carlos F Linares; Freddy Ocanto; Pablo Bretto; Maricela Monsalve

    2014-06-01

    A hydrocalumite-type solid was synthesized by the homogeneous co-precipitation method by using Ca and Al nitrate solutions in a basic medium (NaOH). This solid was calcined at 700 and 900 °C, respectively. Then, solids were characterized by X-ray diffraction, FT–IR spectroscopy and BET surface area measurements. Finally, these solids were tested as antacids by using a synthetic gastric juice. Results showed that calcined samples were able to neutralize the synthetic gastric juice in more extension as an as-synthesized hydrocalumite; however, the last solid showed better conditions as a potential antacid.

  5. Study of structural transformations and phases formation upon calcination of Zn–Ni–Al hydrotalcite nanosheets

    Indian Academy of Sciences (India)

    Zhanshuang Li; Yanchao Song; Jun Wang; Qi Liu; Piaoping Yang; Milin Zhang

    2011-04-01

    In this paper, we describe a general process for the synthesis of highly crystalline Zn–Ni–Al hydrotalcitelike materials. The structure and thermal decomposition of the prepared samples are studied by XRD, FT–IR, TG–DSC, SEM, TEM and N2 adsorption/desorption. The morphology of large-sized, porous and hexagonal platelike Zn–Ni–Al hydrotalcite is affected by calcination temperature. BET specific surface area and pore volume are observed to increase with increase of the calcination temperature up to 700°C followed by a further decrease with increasing temperature.

  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. Aggregation and Averaging.

    Science.gov (United States)

    Siegel, Irving H.

    The arithmetic processes of aggregation and averaging are basic to quantitative investigations of employment, unemployment, and related concepts. In explaining these concepts, this report stresses need for accuracy and consistency in measurements, and describes tools for analyzing alternative measures. (BH)

  8. 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.

  9. Cell aggregation and sedimentation.

    Science.gov (United States)

    Davis, R H

    1995-01-01

    The aggregation of cells into clumps or flocs has been exploited for decades in such applications as biological wastewater treatment, beer brewing, antibiotic fermentation, and enhanced sedimentation to aid in cell recovery or retention. More recent research has included the use of cell aggregation and sedimentation to selectively separate subpopulations of cells. Potential biotechnological applications include overcoming contamination, maintaining plasmid-bearing cells in continuous fermentors, and selectively removing nonviable hybridoma cells from perfusion cultures.

  10. 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.

  11. 石油焦煅烧技术方案比较%Comparison of calcination technical schemes of petroleum coke

    Institute of Scientific and Technical Information of China (English)

    穆二军; 刘慧

    2013-01-01

    This paper presents comparisons of different calcination technologies,such as the vertical shaft calciner, rotary kiln,rotary hearth furnace and electrically calcined furnace. The comparisons from process performance perspective, thermodynamic principle, calcination technology, calcination product quality, environment of engineering construction and the main technical and economic indexes etc., are made. The characteristics of different calcination technologies in the production of anode used in aluminum industry are discussed, the advantages and disadvantages of different calcination technology are analyzed, and further optimizing for the design and operation of the main calcination technology is pointed out.%对罐式炉、回转窑、回转床、电煅炉等炭素煅烧处理方式从工艺流程、热工原理、煅烧工艺技术、煅烧质量、工程建设环境及主要技术经济指标等方面进行综合比较;基于目前生石油焦质量与供应等情况,讨论了石油焦煅烧技术对生产铝用阳极焦的适应性;分析了不同煅烧方式的优缺点,提出了对主要煅烧技术需进一步优化设计与工艺操作的建议.

  12. Effect of sulfuric acid concentration of bentonite and calcination time of pillared bentonite

    Science.gov (United States)

    Mara, Ady; Wijaya, Karna; Trisunaryati, Wega; Mudasir

    2016-04-01

    An activation of natural clay has been developed. Activation was applied by refluxing the natural bentonite in variation of the sulfuric acid concentration and calcination time of pillared bentonite (PLC). Calcination was applied using oven in microwave 2,45 GHz. Determination of acidity was applied by measuring the amount of adsorbed ammonia and pyridine. Morphological, functional groups and chrystanility characterizations were analyzed using SEM, TEM, FTIR and XRD. Porosity was analyzed using SSA. The results showed that the greater of the concentration of sulfuric acid and calcination time was, the greater the acidity of bentonite as well as the pore diameter were. FTIR spectra showed no fundamental changes in the structure of the natural bentonite, SEM, and TEM images were showing an increase in space or field due to pillarization while the XRD patterns showed a shift to a lower peak. Optimization was obtained at a concentration of 2 M of sulfuric acid and calcination time of 20 minutes, keggin ion of 2.2 and suspension of 10 mmol, respectively each amounted to 11.7490 mmol/gram of ammonia and 2.4437 mmol/gram of pyridine with 154.6391 m2/gram for surface area, 0.130470 m3/gram of pore volume and 3.37484 nm of pore diameter.

  13. Calcined eggshell (CES): An efficient natural catalyst for Knoevenagel condensation under aqueous condition

    Indian Academy of Sciences (India)

    Suresh Patil; Swati D Jadhav; M B Deshmukh

    2013-07-01

    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 renewable resources.

  14. Restart Plan for the Prototype Vertical Denitration Calciner [SD Coversheet has Incorrect Document Number

    Energy Technology Data Exchange (ETDEWEB)

    SUTTER, C.S.

    1999-07-26

    Testing activities on the Prototype Vertical Denitration Calciner at PFP were suspended in January 1997 due to the hold on fissile material handling in the facility. The Restart Plan will govern the transition of the test program from the completion of the activity based startup review; through equipment checkout and surrogate material runs; to resumption of the testing program and transition to unrestricted testing.

  15. 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.

  16. 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 fo

  17. Effect of Boric Acid on Properties of Calcined Flint Clay-Bauxite Castables

    Institute of Scientific and Technical Information of China (English)

    ZHANG Wei; DAI Wenyong

    2010-01-01

    In order to prolong the working time of calcined flint clay-bauxite castables during construction at high temperature,boric acid was added into the castables.The effect of boric acid on working time and curing cold crushing strength of the castables at 25 ℃ and 35 ℃were investigated.After 24 h curing in mould and another 24 h curing at 110 ℃ after demoulding,the specimens were heat treated at 1 000 ℃,1 300 ℃,and1 500 ℃ for 3 h,respectively.The permanent linear change,bulk density,modulus of rupture,and cold crushing strength were determined.The result shows that there is no need to add boric acid when calcined flint clay-bauxite ca.stables works at 25 ℃ ; when calcined flint clay-bauxite castables works at 35 ℃,boric acid can increase the working time of the castables,but decrease the curing cold crushing strength a little.Adding boric acid into calcined flint clay-bauxite castables doesn' t worsen performance of the castablcs.

  18. Calcination/acid-activation treatment of an anodic oxidation TiO2/Ti film catalyst

    Institute of Scientific and Technical Information of China (English)

    YAO Zhongping; JIANG Yanli; JIANG Zhaohua; ZHU Hongkui; BAI Xuefeng

    2009-01-01

    The aim of this work was to investigate the effects of calcination/acid-activation on the composition, structure, and photocatalytic (PC) re-duction property of an anodic oxidation TiO2/Ti film catalyst. The surface morphology and phase composition were examined by scanning electron microscopy and X-ray diffraction. The catalytic property of the film catalysts was evaluated through the removal rate of potassium chromate during the PC reduction process. The results showed that the film catalysts were composed of anatase and mtile TiO2 with a mi-cro-porous surface structure. The calcination treatment increased the content of TiO2 in the film, changed the relative ratio of anatase and rutile TiO2, and decreased the size of the micro pores of the film cat.a/ysts. The removal rate of potassium chromate was related to the tech-nique parameters of calcination/acid-activation treatment. When the anodic oxidation TiO2Ti film catalyst was calcined at 873 K for 30 min and then acid-activated in the concentrated H2SO4 for 60 min, it presented the highest catalytic property, with the removal rate of potassium chromate of 96.3% during the PC reduction process under the experimental conditions.

  19. Effect of calcination methods on electrochemical performance of NiO used as electrode materials for supercapacitor

    Indian Academy of Sciences (India)

    L Wang; X Y Qin

    2014-05-01

    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 others were calcination in a muffle furnace. The products were well-characterized by thermogravimetric analysis (TGA), X-ray diffraction (XRD) and scanning electron microscopy (SEM). The influence of calcination methods on electrochemical performance of NiO samples were investigated. Moreover, the possible reason was proposed. The charge storage mechanism of NiO positive electrode in aqueous electrolyte was discussed. The electrochemical test showed that the as-prepared NiO prepared in a tube furnace can exhibit a good pseudocapacitance behaviour due to the higher utilization of active material.

  20. Extraction of potassium from K-feldspar via the CaCl2 calcination route☆

    Institute of Scientific and Technical Information of China (English)

    Bo Yuan; Chun Li; Bin Liang; Li Lü; Hairong Yue; Haoyi Sheng; Longpo Ye; Heping Xie

    2015-01-01

    The extraction of potassium from K-feldspar via a calcium chloride calcination route was studied with a focus on the effects of the calcination atmosphere, calcination temperature and time, mass ratio of CaCl2 to K-feldspar ore and particle size of the K-feldspar ore. The results demonstrated that a competing high-temperature hydrolysis reaction of calcium chloride with moisture in a damp atmosphere occurred concurrently with the conversion reaction of K-feldspar with CaCl2, thus reducing the amount of potassium extracted. The conversion reaction started at approximately 600 °C and accelerated with increasing temperature. When the temperature rose above 900 °C, the extraction of potassium gradually decreased due to the volatilization of the product, KCl. As much as approximately 41%of the potassium was volatilized in 40 min at 1100 °C. The mass ratio of CaCl2/K-feldspar ore significantly affected the extraction. At a mass ratio of 1.15 and 900 °C, the potassium extraction reached 91%in 40 min, while the extraction was reduced to only 22%at the theoretical mass ratio of 0.2. Optimal process conditions are as follows:ore particle size of 50–75μm, tablet forming pressure of 3 MPa, dry nitrogen atmosphere, mass ratio of CaCl2/ore 1.15:1, calcination temperature of 900 °C, and calcination time of 40 min. The XRD analysis revealed that a complex phase transition of the product SiO2 was also accompanied by the con-version reaction of K-feldspar/CaCl2. The SiO2 product formed at the initial stage was in the quartz phase at 900 °C and was gradually transformed into cristobalite after 30 min.

  1. Optical dynamics of molecular aggregates

    NARCIS (Netherlands)

    de Boer, Steven

    2006-01-01

    The subject of this thesis is the spectroscopy and dynamics of molecular aggregates in amorphous matrices. Aggregates of three different molecules were studied. The molecules are depicted in Fig. (1.1). Supersaturated solutions of these molecules show aggregate formation. Aggregation is a process si

  2. 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%).

  3. Fractals of Silica Aggregates

    Institute of Scientific and Technical Information of China (English)

    ZhinhongLi; DongWu; Yuhansun; JunWang; YiLiu; BaozhongDong; Zhinhong

    2001-01-01

    Silica aggregates were prepared by base-catalyzed hydrolysis and condensation of alkoxides in alcohol.Polyethylene glycol(PEG) was used as organic modifier.The sols were characterized using Small Angle X-ray Scattering (SAXS) with synchrotron radiation as X-ray source.The structure evolution during the sol-gel process was determined and described in terms of the fractal geometry.As-produced silica aggregates were found to be mass fractals.The fractl dimensions spanned the regime 2.1-2.6 corresponding to more branched and compact structures.Both RLCA and Eden models dominated the kinetic growth under base-catalyzed condition.

  4. Influence of the Calcination Temperature on the Combustion Synthesized Perovskite LaMnO3 Compound

    Directory of Open Access Journals (Sweden)

    A.R. Shelke

    2015-10-01

    Full Text Available A simple combustion method based on principles of propellent chemistry in which Polyvinyl alcohol (PVA as fuel and nitrates as oxidizer were used for synthesizing the perovskite like LaMnO3 powders. The oxidizer to fuel ratio was maintained at 5 : 1. The darkish black powder obtained was calcined at 800 °C and 1000 °C for 5 hour. The combustion and thermal decomposition of the precursor were investigated using the TG-DTA and Fourier Transform Infra-Red (FT-IR techniques. The X-ray diffraction (XRD pattern of all three samples i.e., un-heated LaMnO3 powder (LMO-UH, calcined at 800 °C (LMO-800 and at 1000 °C (LMO-1000 were carried out. The single phase orthorhombic crystal structure was revealed to crystallize at LMO-800 and LMO-1000 with elevation in the crystalline size. A small impurity peak at 28.7° was seen of Mn3O4 for LMO-UH, which vanished after calcining it. The strong absorption in FT-IR spectra found at around 615 cm – 1 was due to the formation of metal-oxygen (M-O bond. Moreover a small shift in this M-O bond with increase in calcination temperature suggested the strained LaMnO3 compound. Elemental analysis using the energy dispersive X-ray fluorescence spectrometer (EDXRF indicated the presence of La and Mn with increase in the Mn contents after calcinations. The oxygen, nitrogen and hydrogen content in the sample were determined from the ONH analysis indicating a decrease in the oxygen content for LMO-800. Well defined porous-foam like morphology of the sample was achieved from scanning electron microscopic (SEM study, which become compact with calcination process. Magnetic properties were found to transform from the ferromagnetic-to-paramagnetic phase for LMO-UH sample, while reduction in magnetization values and coercivity at low temperatures was obtained for LMO-800 and LMO-1000 samples.

  5. A facile thermal-treatment route to synthesize ZnO nanosheets and effect of calcination temperature.

    Directory of Open Access Journals (Sweden)

    Naif Mohammed Al-Hada

    Full Text Available A facile thermal-treatment route was successfully used to synthesize ZnO nanosheets. Morphological, structural, and optical properties of obtained nanoparticles at different calcination temperatures were studied using various techniques. The FTIR, XRD, EDX, SEM and TEM images confirmed the formation of ZnO nanosheets through calcination in the temperature between 500 to 650 °C. The SEM images showed a morphological structure of ZnO nanosheets, which inclined to crumble at higher calcination temperatures. The XRD and FTIR spectra revealed that the samples were amorphous at 30 °C but transformed into a crystalline structure during calcination process. The average particle size and degree of crystallinity increased with increasing calcination temperature. The estimated average particle sizes from TEM images were about 23 and 38 nm for the lowest and highest calcination temperature i.e. 500 and 650 °C, respectively. The optical properties were determined by UV-Vis reflection spectrophotometer and showed a decrease in the band gap with increasing calcination temperature.

  6. Erosion of dust aggregates

    CERN Document Server

    Seizinger, Alexander; Kley, Wilhelm

    2013-01-01

    Aims: The aim of this work is to gain a deeper insight into how much different aggregate types are affected by erosion. Especially, it is important to study the influence of the velocity of the impacting projectiles. We also want to provide models for dust growth in protoplanetary disks with simple recipes to account for erosion effects. Methods: To study the erosion of dust aggregates we employed a molecular dynamics approach that features a detailed micro-physical model of the interaction of spherical grains. For the first time, the model has been extended by introducing a new visco-elastic damping force which requires a proper calibration. Afterwards, different sample generation methods were used to cover a wide range of aggregate types. Results: The visco-elastic damping force introduced in this work turns out to be crucial to reproduce results obtained from laboratory experiments. After proper calibration, we find that erosion occurs for impact velocities of 5 m/s and above. Though fractal aggregates as ...

  7. Diffusion in aggregated soil.

    NARCIS (Netherlands)

    Rappoldt, C.

    1992-01-01

    The structure of an aggregated soil is characterized by the distribution of the distance from an arbitrary point in the soil to the nearest macropore or crack. From this distribution an equivalent model system is derived to which a diffusion model can be more easily applied. The model system consist

  8. Effect of Reaction Rate and Calcination Time on CaNb2O6 Nanoparticles

    Directory of Open Access Journals (Sweden)

    C. M. Dudhe

    2014-01-01

    Full Text Available The properties of CaNb2O6 nanoparticles synthesized by coprecipitation method under controlled reaction rate and extended calcination time were studied. Analysis of the X-ray diffraction pattern shows single orthorhombic phase of the material with lattice parameters: a=15.0147 Å, b=5.74148 Å, and c=5.30296 Å. The morphology and size of particles was found to be improved due to the controlled reaction rate and extended calcination time. The average sizes of the particles were estimated as 40 nm and 90 nm for sintering temperatures 650°C and 800°C, respectively. The material was found to possess dielectric constant which is inversely proportional to the frequency. Surprisingly, the material shows ferroelectric behavior, the possible origin of which is discussed here.

  9. 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.

  10. Influence of Calcination on the Physical Characteristics and Nitrogen Removal Performance of Clinoptilolites

    Institute of Scientific and Technical Information of China (English)

    LIN Hai; JIN Xin; DONG Yingbo; HUO Hanxin; LIU Quanli

    2014-01-01

    The influences of roasting activation on the particle morphology, microscopic structure, and adsorption properties of natural clinoptilolites were investigated. The experimental results show that the optimal modified conditions include a calcination temperature at 400℃, a roasting time of 0.5 h, and furnace cooling. The ammonia nitrogen removal rate from analog renewable water of the modified clinoptilolites reached 72%in the optimized conditions, which is 12%higher than that of natural ones. Scanning electron microscopy analysis showed that the surface morphology changed, the micro-hole size increased, and the surface became smoother and more uniform after calcination. The single-point total adsorption average pore width increased from 7.74 nm to 10.64 nm.

  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.

  12. 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...

  13. 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.

  14. A parametric study of a solar calcinator using computational fluid dynamics

    Energy Technology Data Exchange (ETDEWEB)

    Fidaros, D.K.; Baxevanou, C.A.; Vlachos, N.S. [University of Thessaly, Volos (Greece). Laboratory of Fluid Mechanics and Turbomachines, Department of Mechanical and Industrial Engineering

    2007-11-15

    In this work a horizontal rotating solar calcinator is studied numerically using computational fluid dynamics. The specific solar reactor is a 10 kW model designed and used for efficiency studies. The numerical model is based on the solution of the Navier-Stokes equations for the gas flow, and on Lagrangean dynamics for the discrete particles. All necessary mathematical models were developed and incorporated into a computational fluid dynamics model with the influence of turbulence simulated by a two-equation (RNG k-{epsilon}) model. The efficiency of the reactor was calculated for different thermal inputs, feed rates, rotational speeds and particle diameters. The numerically computed degrees of calcination compared well with equivalent experimental results. (author)

  15. Bone mineral change during experimental calcination: an X-ray diffraction study.

    Science.gov (United States)

    Galeano, Sergio; García-Lorenzo, Mari Luz

    2014-11-01

    The effects of calcination (400-1200°C) on pig bones have been studied using powder X-ray diffraction (XRD) and secondary modifications, such as color change and weight loss. The characterisation by powder XRD confirmed the presence of the crystalline phase of hydroxyapatite, and comparison of the results obtained at different temperatures suggested that at 650°C, all the organic components and carbonate substitutions were completely removed. Accordingly, these samples were white. In addition, the crystallinity degree and the crystallite size progressively increased with the calcination temperature until 650°C, remaining stable until 1200°C. Below 650°C, bone samples presented organic compounds, resulting in background noise in the diffractogram and gray or black color. In addition, impurities in the lattice correspond to low crystallite sizes.

  16. Prediction model of microwave calcining of ammonium diuranate using incremental improved back-propagation neural network

    Institute of Scientific and Technical Information of China (English)

    Yingwei LI; Bingguo LIU; Jinhui PENG; Wei LI; Daifu HUANG; Libo ZHANG

    2011-01-01

    The incremental improved Back-Propagation (BP) neural network prediction model using the Levenberg-Marquardt algorithm based on optimizing theory is put forward,which can solve the problems existing in the process of calcinations for ammonium diuranate (ADU) by microwave heating,such as long testing cycle,high testing quantity,difficulty of optimization for process parameters. Many training data probably were offered by the way of increment batch and the limitation of the system memory could make the training data infeasible when the sample scale was large. The prediction model of the nonlinear system is built,which can effectively predict the experiment of microwave calcining of ADU,and the incremental improved BP neural network is very useful in overcoming the local minimum problem,finding the global optinal solution and accelerating the convergence speed.

  17. Preparation of ITO nano-powders by hydrothermal-calcining process

    Institute of Scientific and Technical Information of China (English)

    GU Ying-ying; QIN Li-ping; LIU Xue-ying

    2006-01-01

    Sn-doped In2O3 (ITO) nano-powders were prepared by hydrothermal-calcining process. Using SnCl4·5H2O and In as starting materials, the crystallites were characterized by XRD, TEM and BET. The effects of the conditions on the product were investigated. The results show that the phase of hydrothermal precursor obtained by hydrothermal process is related to the temperature of hydrothermal reaction, I. E. , the phases are amorphous In(OH)3 in 160 - 180℃; In(OH)3 crystal in 200℃ and (In1-xSnx)OOH crystal in 200 - 300℃. ITO nano-powders with hexagonal structure and average size of 65 nm are obtained by calcining the precursor derived from the hydrothermal process at 350 - 650℃. The BET of ITO crystal can reach 84. 023 4 m2·g-1.

  18. Limestone Calcination Nearby Equilibrium: Kinetics, CaO Crystal Structure, Sintering and Reactivity

    OpenAIRE

    Valverde, J.M.; Sánchez-Jiménez, P.E.; Pérez-Maqueda, Luis A.

    2015-01-01

    © 2015 American Chemical Society. In this work, we analyze limestone calcination kinetics at environmental conditions involving a CO2 partial pressure P close to the equilibrium pressure Peq by means of in situ X-ray diffraction (XRD) and thermogravimetric (TG) analyses. In contrast with previous empirical observations carried out mostly at conditions far from equilibrium (P/Peq « 1), our results show that the decarbonation rate decreases as the temperature in increased while P/Peq is kept co...

  19. 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.

  20. Preparation of NiO nanoflakes under different calcination temperatures and their supercapacitive and optical properties

    Science.gov (United States)

    Zhao, Jiangshan; Liu, Hua; Zhang, Qiang

    2017-01-01

    The NiO nanocrystals were successfully prepared by calcinating Ni(OH)2 precursor synthesized via a facile ion diffusion controlled by ion exchange membrane without adding any solvent or template. X-ray diffraction (XRD), scanning electron microscopy (SEM), Brunauer-Emmett-Teller (BET) isotherm, X-ray photoelectron spectroscopy (XPS) and Ultraviolet-visible (UV-vis) analysis were used to investigate the crystallinity, morphology, surface and porosity characteristics, chemical composition and optical properties in more detail. The pseudocapacitive behavior of the NiO samples was investigated by cyclic voltammograms (CV) and galvanostatic charge-discharge tests in 2 M KOH. The results analysis reveals that both specific capacitance and surface area decrease with the increase of calcination temperatures. Among the NiO samples, the NiO-400 nanoflakes calcinated at 400 °C possess the highest specific capacitance of 381 F g-1 at a current density of 2 A g-1, but much lower than the Ni(OH)2 sample. In addition, the UV-vis analysis shows that there is a red shift of absorption peak for the three NiO samples with the increasing temperature and the NiO-400 has a broad band gap of 3.3 eV, which renders the material highly interesting for application in photocatalyst.

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

    Energy Technology Data Exchange (ETDEWEB)

    COMPTON, J.A.

    1999-08-13

    The prototype Vertical Denitration Calciner (VDC) is installed in glovebox 188 in the Plutonium Process Support Laboratory (PPSL). Safety analysis contained in WHC-SD-CP-SAR-021 (FSAR) Rev. 0-L and Addendum to WHC-SD-CP-SAR-021, ''Laboratory Prototype Calciner'' establishes the prototype VDC needs to be shut down if a seismic event of greater than 0.07 g occurs. Shut down is to be automatic upon detection of the seismic event. This requires tie-in of various valves and power for the prototype VDC into the existing Seismic Shutdown System for the Ventilation Supply Fans described in FSAR 5.4.1.2.4. The proposed changes covered by this USQ evaluation include: (1) the physical tie-in modifications, including drawings and Engineering Change Notice (ECN), (2) the work package for accomplishing the modifications, (3) the changes to the System Description Documents, (4) the changes to the Safety Equipment List necessitated by the modifications, and (5) the changes to the failure modes and effects analysis. WHC-SDCP-OSR-010, Plutonium Finishing Plant Operational Safety Requirements Limiting Condition for Operation (LCO) 3.2.3 has been revised to include the requirement for the existing seismic shutdown system to also shut down the laboratory calciner in the event of detection of a greater than 0.07 g seismic event.

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

    Energy Technology Data Exchange (ETDEWEB)

    COMPTON, J.A.

    1999-08-31

    The prototype Vertical Denitration Calciner (VDC) is installed in glovebox 188 in the Plutonium Process Support Laboratory (PPSL). Safety analysis contained in WHC-SD-CP-SAR-021 (FSAR) Rev. 0-L and Addendum to WHC-SD-CP-SAR-021, ''Laboratory Prototype Calciner'' establishes the prototype VDC needs to be shut down if a seismic event of greater than 0.07 g occurs. Shut down is to be automatic upon detection of the seismic event. This requires tie-in of various valves and power for the prototype VDC into the existing Seismic Shutdown System for the Ventilation Supply Fans described in FSAR 5.4.1.2.4. The proposed changes covered by this USQ evaluation include: (1) the physical tie-in modifications, including drawings and Engineering Change Notice (ECN), (2) the work package for accomplishing the modifications, (3) the changes to the System Description Documents, (4) the changes to the Safety Equipment List necessitated by the modifications, and (5) the changes to the failure modes and effects analysis. WHC-SDCP-OSR-010, Plutonium Finishing Plant Operational Safety Requirements Limiting Condition for Operation (LCO) 3.2.3 has been revised to include the requirement for the existing seismic shutdown system to also shut down the laboratory calciner in the event of detection of a greater than 0.07 g seismic event.

  3. 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.

  4. High-level waste vitrification by spray calcination/in-can melting

    Energy Technology Data Exchange (ETDEWEB)

    Larson, D.E.; Bonner, W.F. (comp.)

    1976-11-01

    Federal regulations require that high-level liquid waste (HLLW) be converted to a solid for custody in a Federal repository. The Spray Solidification/In-Can Melting process has been developed and is being demonstrated for commercial application. The bases used are similar to those of the NFS plant and to anticipated regulations for waste canister receipt at a Federal repository. The reference NFS flowsheet combines plant HA Column Wastes, Low-Level Wastes, and various HLLW process recycle streams to produce a borosilicate glass. After the canister is filled and sealed, the lid weld will be inspected and decontaminated. Equipment and instrumentation for feed supply to the calciner, calcination, melting, welding, weld inspection, canister decontamination, and in-cell canister storage are being designed and demonstrated. Preliminary facility layouts, equipment design data, and instrumentation needs are provided for major process equipment systems. Additional demonstration work is being performed to verify and complete the plant scale equipment design, including full-scale nonradioactive equipment testing, nonradioactive facility mockup for equipment remote operation and maintenance demonstration, and pilot plant production of waste glass from commercial fuel HLLW. The technology for spray calcination and in-can melting is ready for commercial application. Required additional work is described. A preliminary evaluation is made of materials that may be released from the process from normal and abnormal operations in the facility. 34 figures, 20 tables. (DLC)

  5. 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.

  6. 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)

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

    Energy Technology Data Exchange (ETDEWEB)

    Ramasamy, Karthikeyan K. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States). Chemical and Biological Process Development Group and Inst. for Integrated Catalysis; Gray, Michel [Pacific Northwest National Lab. (PNNL), Richland, WA (United States). Chemical and Biological Process Development Group; Job, Heather [Pacific Northwest National Lab. (PNNL), Richland, WA (United States). Chemical and Biological Process Development Group; Santosa, Daniel [Pacific Northwest National Lab. (PNNL), Richland, WA (United States). Chemical and Biological Process Development Group; Li, Xiaohong Shari [Pacific Northwest National Lab. (PNNL), Richland, WA (United States). Inst. for Integrated Catalysis; Devaraj, Arun [Pacific Northwest National Lab. (PNNL), Richland, WA (United States). Environmental Molecular Sciences Lab. (EMSL); Karkamkar, Abhi [Pacific Northwest National Lab. (PNNL), Richland, WA (United States). Chemical and Biological Process Development Group; Wang, Yong [Pacific Northwest National Lab. (PNNL), Richland, WA (United States). Chemical and Biological Process Development Group and Inst. for Integrated Catalysis; ; Washington State Univ., Pullman, WA (United States)

    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.

  8. Hydrophobic aggregation of ultrafine kaolinite

    Institute of Scientific and Technical Information of China (English)

    ZHANG Xiao-ping; HU Yue-hua; LIU Run-Qing

    2008-01-01

    The hydrophobic aggregation of ultrafine kaolinite in cationic surfactant suspension was investigated by sedimentation test, zeta potential measurement and SEM observation. SEM images reveal that kaolinite particles show the self-aggregation of edge-face in acidic media, the aggregation of edge-face and edge-edge in neutral media, and the dispersion in alkaline media due to electrostatic repulsion. In the presence of the dodecylammonium acetate cationic surfactant and in neutral and alkaline suspension, the hydrophobic aggregation of face-face is demonstrated. The zeta potential of kaolinite increases with increasing the concentration of cationic surfactant. The small and loose aggregation at a low concentration but big and tight aggregation at a high concentration is presented At pH=7 alkyl quarterly amine salt CTAB has the best hydrophobic aggregation among three cationic surfactants, namely, dodecylammonium acetate, alkyl quarterly amine salts 1227 and CTAB.

  9. Absorption Spectra of Astaxanthin Aggregates

    CERN Document Server

    Olsina, Jan; Minofar, Babak; Polivka, Tomas; Mancal, Tomas

    2012-01-01

    Carotenoids in hydrated polar solvents form aggregates characterized by dramatic changes in their absorption spectra with respect to monomers. Here we analyze absorption spectra of aggregates of the carotenoid astaxanthin in hydrated dimethylsulfoxide. Depending on water content, two types of aggregates were produced: H-aggregates with absorption maximum around 390 nm, and J-aggregates with red-shifted absorption band peaking at wavelengths >550 nm. The large shifts with respect to absorption maximum of monomeric astaxanthin (470-495 nm depending on solvent) are caused by excitonic interaction between aggregated molecules. We applied molecular dynamics simulations to elucidate structure of astaxanthin dimer in water, and the resulting structure was used as a basis for calculations of absorption spectra. Absorption spectra of astaxanthin aggregates in hydrated dimethylsulfoxide were calculated using molecular exciton model with the resonance interaction energy between astaxanthin monomers constrained by semi-e...

  10. 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.

  11. Adsorption of phosphate ions from an aqueous solution by calcined nickel-cobalt binary hydroxide.

    Science.gov (United States)

    Ogata, Fumihiko; Ueta, Erimi; Toda, Megumu; Otani, Masashi; Kawasaki, Naohito

    2017-01-01

    Different molar ratios of a Ni/Co binary hydroxide (NiCo82, NiCo91, and Ni100) were prepared and calcined at 270 °C (NiCo82-270, NiCo91-270, and Ni100-270). The properties of the adsorbents and the amount of adsorbed phosphate ions were evaluated. The adsorbents calcined at 270 °C had a nickel oxide structure. The amount of adsorbed phosphate ions, the amount of hydroxyl groups, and the specific surface area of the calcined adsorbents at 270 °C were greater than those of the uncalcined adsorbents. The amount of adsorbed phosphate ions was related to the amount of hydroxyl groups and the specific surface area; the correlation coefficients were 0.966 and 0.953, respectively. The adsorption isotherm data for NiCo91 and NiCo91-270 were fit to both the Freundlich and Langmuir equations. The amount of adsorbed phosphate ions increased with increasing temperature. The experimental data fit the pseudo-second-order model better than the pseudo-first-order model. A neutral pH was optimal for phosphate ion adsorption. In addition, the phosphate ions that were adsorbed onto NiCo91-270 could be recovered using sodium hydroxide, and the adsorbent was useful for the repetitive adsorption/desorption of phosphate ions. Collectively, these results suggest that NiCo91-270 is prospectively useful for the adsorption of phosphate ions from aqueous solutions.

  12. Structure and Pozzolanic Activity of Calcined Coal Gangue during the Process of Mechanical Activation

    Institute of Scientific and Technical Information of China (English)

    GUO Wei; LI Dongxu; CHEN Jianhua; YANG Nanru

    2009-01-01

    On the basis of analyzing coal gangue's chemical and mineral compositions, the structure change of coal gangue during the mechanical activation was investigated by XRD, FTIR,NMR, and the mechanical strength of the cement doped coal gangue with various specific surface area was tested. The experimental results indicate that, the lattice structure of metakaolin in coal gangue samples calcined at 700 ℃ disorganizes gradually and becomes disordered, and the lattice structure of α-quartz is distorted slightly. The pozzolanic activity of the coal gangue increases obviously with its structural disorganization.

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

    OpenAIRE

    Cancan Fan; Xitao Wang; Huanxin Sang; Fen Wang

    2012-01-01

    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 ...

  14. 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.

  15. Fractal Aggregation Under Rotation

    Institute of Scientific and Technical Information of China (English)

    WU Feng-Min; WU Li-Li; LU Hang-Jun; LI Qiao-Wen; YE Gao-Xiang

    2004-01-01

    By means of the Monte Carlo simulation, a fractal growth model is introduced to describe diffusion-limited aggregation (DLA) under rotation. Patterns which are different from the classical DLA model are observed and the fractal dimension of such clusters is calculated. It is found that the pattern of the clusters and their fractal dimension depend strongly on the rotation velocity of the diffusing particle. Our results indicate the transition from fractal to non-fractal behavior of growing cluster with increasing rotation velocity, i.e. for small enough angular velocity ω the fractal dimension decreases with increasing ω, but then, with increasing rotation velocity, the fractal dimension increases and the cluster becomes compact and tends to non-fractal.

  16. Fractal Aggregation Under Rotation

    Institute of Scientific and Technical Information of China (English)

    WUFeng-Min; WULi-Li; LUHang-Jun; LIQiao-Wen; YEGao-Xiang

    2004-01-01

    By means of the Monte Carlo simulation, a fractal growth model is introduced to describe diffusion-limited aggregation (DLA) under rotation. Patterns which are different from the classical DLA model are observed and the fractal dimension of such clusters is calculated. It is found that the pattern of the clusters and their fractal dimension depend strongly on the rotation velocity of the diffusing particle. Our results indicate the transition from fractal to non-fractal behavior of growing cluster with increasing rotation velocity, i.e. for small enough angular velocity ω; thefractal dimension decreases with increasing ω;, but then, with increasing rotation velocity, the fractal dimension increases and the cluster becomes compact and tends to non-fractal.

  17. 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...

  18. 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.

  19. 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.

  20. Adsorption of methyl orange from aqueous solutions by calcined ZnMgAl hydrotalcite

    Science.gov (United States)

    Yuan, Dong; Zhou, Liangqin; Fu, Dayou

    2017-02-01

    The calcined ZnMgAl hydrotalcite was used for degration of methyl orange (MO). The adsorbent was characterized by XRD, SEM, and FT-IR. The results reveal that the ZnMgAl layered structures were disappeared after calcining for 5 h at 500 °C, then were recovered to layer hydrotalcite structure after adsorbing MO anions. The several important affecting factors of adsorption behavior, including the initial pH value of solution, adsorbent dosage, and the initial concentration of solution, were also discussed. The adsorption kinetic processes were fitted with the equations of pseudo-first-order, pseudo-second-order, and intraparticle diffusion, respectively, in which the pseudo-second-order equation fitting results was the better. The equilibrium isotherm of MO was described by both Langmuir and Freundlich model, but better complys with the Langmuir model ( R 2 > 0.98). The possible adsorption mechanism has been presumed. The adsorption experiments indicated that the ZnMgAl hydrotalcite had good adsorption ability to methyl orange in wastewater.

  1. Calcined Mg-Fe layered double hydroxide as an absorber for the removal of methyl orange

    Directory of Open Access Journals (Sweden)

    Chao Peng

    2015-05-01

    Full Text Available In this work, methyl orange (MO was effectively removed from aqueous solution with the calcined product of hydrothermal synthesized Mg/Fe layered double hydroxide (Mg/Fe-LDH. The structure, composition, morphology and textural properties of the Mg/Fe-LDH before and after adsorption were characterized by X-ray diffraction, Fourier transformation infrared spectroscopy, transmission electron microscopy, nitrogen adsorption apparatus and X-ray photoelectron spectroscopy. It was confirmed that MO had been absorbed by calcined Mg/Fe-LDH which had strong interactions with MO. The adsorption of MO onto the Mg/Fe-LDH was systematically investigated by batch tests. The adsorption capacity of the Mg/Fe-LDH toward MO was found to be 194.9 mg • g−1. Adsorption kinetics and isotherm studies revealed that the adsorption of MO onto Mg/Fe-LDH was a spontaneous and endothermic process. These results indicate that Mg/Fe-LDH is a promising material for the removal of MO.

  2. Calcined Mg-Fe layered double hydroxide as an absorber for the removal of methyl orange

    Energy Technology Data Exchange (ETDEWEB)

    Peng, Chao [School of Civil Engineering and Mechanics, Central South University of Forestry and Technology, Changsha 410004, Hunan (China); State Key Laboratory of Silicate Materials for Architectures, Wuhan University of Technology, Wuhan 430070 (China); Dai, Jing [Key Laboratory of Advanced Technology for Special Functional Materials of Ministry of Education, Wuhan 430070 (China); Yu, Jianying, E-mail: Yujianyingwhut@163.com [State Key Laboratory of Silicate Materials for Architectures, Wuhan University of Technology, Wuhan 430070 (China); Yin, Jian [School of Civil Engineering and Mechanics, Central South University of Forestry and Technology, Changsha 410004, Hunan (China)

    2015-05-15

    In this work, methyl orange (MO) was effectively removed from aqueous solution with the calcined product of hydrothermal synthesized Mg/Fe layered double hydroxide (Mg/Fe-LDH). The structure, composition, morphology and textural properties of the Mg/Fe-LDH before and after adsorption were characterized by X-ray diffraction, Fourier transformation infrared spectroscopy, transmission electron microscopy, nitrogen adsorption apparatus and X-ray photoelectron spectroscopy. It was confirmed that MO had been absorbed by calcined Mg/Fe-LDH which had strong interactions with MO. The adsorption of MO onto the Mg/Fe-LDH was systematically investigated by batch tests. The adsorption capacity of the Mg/Fe-LDH toward MO was found to be 194.9 mg • g{sup −1}. Adsorption kinetics and isotherm studies revealed that the adsorption of MO onto Mg/Fe-LDH was a spontaneous and endothermic process. These results indicate that Mg/Fe-LDH is a promising material for the removal of MO.

  3. 焙烧短窑研制浅谈%Synopsis Discussing Manufacture of Short Calcining Kiln

    Institute of Scientific and Technical Information of China (English)

    段玉新

    2014-01-01

    介绍了红土镍矿资源现状、红土镍矿的处理工艺方法及焙烧短窑的研发背景。焙烧短窑作为新兴的环保设备,具有螺旋往返快速均匀给料、液压倾翻排料、还原时间可控、热效率高、利用率高的特点,在稀有贵重金属冶炼方面具有非常广泛的应用前景。%T his article briefly introduces present situation of nickeliferous laterites , the processes for pro-ducing nicheliferous laterites and background of inventing short calcining kiln . It is the newly arisen envi-ronmental protection equipments , It has the characteristics of quickly and evenly feeding , discharging with hydraulic pressure , controling deoxidize time ,supernal thermal efficiency and widely using . The short cal-cining kiln have widely using in smelting of the rare noble metal .

  4. Grain Growth Kinetics of BaTiO3 Nanocrystals During Calcining Process

    Science.gov (United States)

    Song, Xiao-lan; He, Xi; Yang, Hai-ping; Qu, Yi-xin; Qiu, Guan-zhou

    2008-06-01

    BaTiO3 nanocrystals were synthesized by sol-gel method using barium acetate (Ba(CH3COO)2) and tetra-butyl titanate (Ti(OC4H9)4) as raw materials. Xerogel precursors and products were characterized by means of thermogravimetric/differential scanning calorimetry (TG/DSC), X-ray diffraction (XRD) and transmission electron microscope (TEM). The influence of the calcination temperature and duration on the lattice constant, the lattice distortion, and the grain size of BaTiO3 nanocrystals was discussed based on the XRD results. The grain growth kinetics of BaTiO3 nanocrystals during the calcination process were simulated with a conventional grain growth model which only takes into account diffusion, and an isothermal model proposed by Qu and Song, which takes into account both diffusion and surface reactions. Using these models, the pre-exponential factor and the activation energy of the rate constant were estimated. The simulation results indicate that the isothermal model is superior to the conventional one in describing the grain growth process, implying that both diffusion and surface reactions play important roles in the grain growth process.

  5. 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.

  6. Grain Growth Kinetics of BaTiO3 Nanocrystals During Calcining Process

    Institute of Scientific and Technical Information of China (English)

    Xiao-lan Song; Xi He; Hai-ping Yang; Yi-xin Qu; Guan-zhou Qiu

    2008-01-01

    BaTiO3 nanocrystals were synthesized by sol-gel method using barium acetate (Ba(CH3COO)2) and tetra- butyl titanate (Ti(OC4H9)4) as raw materials. Xerogel precursors and products were characterized by means of thermogravimetric/differential scanning calorimetry (TG/DSC), X-ray diffraction (XRD) and transmis- sion electron microscope (TEM). The influence of the calcination temperature and duration on the lattice constant, the lattice distortion, and the grain size of BaTiO3 nanocrystals was discussed based on the XRD results. The grain growth kinetics of BaTiO3 nanocrystals during the calcination process were simulated with a conventional grain growth model which only takes into account diffusion, and an isothermal model proposed by Qu and Song, which takes into account both diffusion and surface reactions. Using these models, the pre-exponential factor and the activation energy of the rate constant were estimated. The simulation results indicate that the isothermal model is superior to the conventional one in describing the grain growth process, implying that both diffusion and surface reactions play important roles in the grain growth process.

  7. 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.

  8. 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.

  9. Adsorption of perchlorate from aqueous solution by the calcination product of Mg/(Al-Fe) hydrotalcite-like compounds.

    Science.gov (United States)

    Yang, Yiqiong; Gao, Naiyun; Chu, Wenhai; Zhang, Yongji; Ma, Yan

    2012-03-30

    The calcination products containing Mg(II), Al(III), and Fe(III) in the brucite-like layers with varying Mg/Al/Fe molar ratios at 550°C were used as the adsorbent to remove perchlorate from aqueous solution, while the Mg/(Al-Fe) hydrotalcite compounds were synthesized by co-precipitation method at a constant pH value. The Mg/(Al-Fe) hydrotalcite compounds (HMAF) were characterized by XRD, FT-IR and TG-DTA. The characteristics showed that the layered double hydroxides structures in the HMAF were lost during calcination at 550°C, but were reconstructed subsequent to adsorption of perchlorate, indicating that the 'memory effect' appeared to play an important role in perchlorate adsorption. Batch adsorption studies were conducted under various equilibration conditions, such as molar ratios of Mg/Al/Fe, calcined temperature, different initial solution pH, adsorbent dose, initial perchlorate concentration, and co-existing anions. It was found that the existence of ferric iron in calcined Mg/(Al-Fe) hydrotalcite compound (CHMAF) was favorable to removal of perchlorate from water, and the best ratio of Mg/Al/Fe is 3:0.8:0.2 (CHMAF5%). This study demonstrated that the calcination product of Mg/(Al-Fe) hydrotalcite-like compound was a promising adsorbent for control of the perchlorate pollution in water.

  10. Effects of calcinations temperature and precursor concentration on crystallinity of NiO nanocrystalline powder synthesized via Ethylene Glycol route

    Science.gov (United States)

    Noorlaily, Prawistin; Nugraha, Mohamad Insan; Iskandar, Ferry; Abdullah, Mikrajuddin; Khairurrijal

    2015-04-01

    Nickel Oxide (NiO) nanocrystalline has been successfully synthesized by Ethylene Glycol (EG) route. The samples were prepared using NiCl2.6H2O as precursor, EG as solvent and agglomeration preventing agent, and ammonium bicarbonate as precipitant. In this research, the effect of calcination temperature and precursor concentration were investigated. The experimental result showed that crystallite sizes of NiO were 4.8 nm, 9.1 nm, and 15.3 nm when the calcinations temperature was 300°C, 400°C, and 500°C respectively. It was obvious that when calcinations temperature increased, the crystallite size of NiO increased, then the calculated activation energy for NiO nanocrystalline growth during calcinations is 21.33 kJmol-1.In the effect of precursor concentration,by using concentrations 0.25 M, 0.5 M, and 1 M, crystallite sizes increase with the increasing concentration as 17.4 nm, 15.7 nm, and 24.8 nm respectively. These result implied that crystallite size of NiO powder can be controlled not only by calcinations temperature but also controlled by precursor concentration.

  11. Calcinated calcium killing of Escherichia coli O157:H7, Salmonella, and Listeria monocytogenes on the surface of tomatoes.

    Science.gov (United States)

    Bari, M L; Inatsu, Y; Kawasaki, S; Nazuka, E; Isshiki, K

    2002-11-01

    This study was conducted to evaluate the efficacy of calcinated calcium, 200 ppm chlorine water (1% active chlorine), and sterile distilled water in killing Escherichia coli O157:H7, Salmonella, and Listeria monocytogenes on the surfaces of spot-inoculated tomatoes. Inoculated tomatoes were sprayed with calcinated calcium, chlorinated water, or sterile distilled water (control) and hand rubbed for 30 s. Populations of E coli O157:H7, Salmonella, and L. monocytogenes in the rinse water and in the residual (0.1% peptone) wash solution were determined. Treatment with 200 ppm chlorine and calcinated calcium resulted in 3.40- and 7.85-log10 reductions of E. coli O157:H7, respectively, and 2.07- and 7.36-log10 reductions of Salmonella, respectively. Treatment with 200 ppm chlorine and calcinated calcium reduced L monocytogenes numbers by 2.27 and 7.59 log10 CFU per tomato, respectively. The findings of this study suggest that calcinated calcium could be useful in controlling pathogenic microorganisms in fresh produce.

  12. Relevant influence of limestone crystallinity on CO₂ capture in the Ca-looping technology at realistic calcination conditions.

    Science.gov (United States)

    Valverde, J M; Sanchez-Jimenez, P E; Perez-Maqueda, L A

    2014-08-19

    We analyze the role of limestone crystallinity on its CO2 capture performance when subjected to carbonation/calcination cycles at conditions mimicking the Ca-looping (CaL) technology for postcombustion CO2 capture. The behavior of raw and pretreated limestones (milled and thermally annealed) is investigated by means of thermogravimetric analysis (TGA) tests under realistic sorbent regeneration conditions, which necessarily involve high CO2 partial pressure in the calciner and quick heating rates. The pretreatments applied lead to contrasting effects on the solid crystal structure and, therefore, on its resistance to solid-state diffusion. Our results show that decarbonation at high CO2 partial pressure is notably promoted by decreasing solid crystallinity. CaO regeneration is fully achieved under high CO2 partial pressure at 900 °C in short residence times for the milled limestone whereas complete regeneration for raw limestone requires a minimum calcination temperature of about 950 °C. Such a reduction of the calcination temperature and the consequent mitigation of multicyclic capture capacity decay would serve to enhance the efficiency of the CaL technology. On the other hand, the results of our study suggest that the use of highly crystalline limestones would be detrimental since excessively high calcination temperatures should be required to attain full decarbonation at realistic conditions.

  13. 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.

  14. Study on Effects of Calcine Conditions on Physic-chemical Character of Calcined Kaolinite%煅烧条件对煤系煅烧高岭土物化性能影响的研究

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    The effects of material fines,calcinating temperature,raising temperature's velocity,addition agent as well as hydrogenant condition on physic-chemical character of calcined kaolinite are investigated.%研究了煤系高岭土在煅烧过程中原料细度、煅烧温度、恒温时间、升温速度、添加剂及还原气氛对产品物化性能的影响。

  15. Effects of precoating and calcination on microstructure of 3D silica fiber reinforced silicon nitride based composites

    Institute of Scientific and Technical Information of China (English)

    QI Gong-jin; ZHANG Chang-rui; HU Hai-feng

    2006-01-01

    Three-dimensional silica fiber reinforced silicon nitride based composites were fabricated by preceramic polymer infiltration and pyrolysis method using perhydropolysilazane as a precursor. The effects of precoating and high temperature calcination on the microstructures of the composites were investigated by scanning electron microscopy. For the composite without a precoating, the fracture surface is plain, and the fiber/matrix interfaces become very unclear after calcination at 1 600 ℃ due to intense interfacial reactions. The composite with a precoating shows tough fracture surface with distinct fiber pull-outs, and the fiber/matrix interfaces are still clear after calcination at 1 600 ℃. It is the appropriate precoating process that contributes to the good interfacial microstructures for the composite.

  16. Aggregate resources in the Netherlands

    NARCIS (Netherlands)

    Meulen, M.J. van der; Gessel, S.F. van; Veldkamp, J.G.

    2005-01-01

    We have built a 3D lithological model of the Netherlands, for the purpose of mapping on-land aggregate resources down to 50 m below the surface. The model consists of voxel cells (1000 · 1000 · 1 m), with lithological composition and aggregate content estimates as primary attributes. These attribute

  17. 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 characteri

  18. Process optimization for Ni(II) removal from wastewater by calcined oyster shell powders using Taguchi method.

    Science.gov (United States)

    Yen, Hsing Yuan; Li, Jun Yan

    2015-09-15

    Waste oyster shells cause great environmental concerns and nickel is a harmful heavy metal. Therefore, we applied the Taguchi method to take care of both issues by optimizing the controllable factors for Ni(II) removal by calcined oyster shell powders (OSP), including the pH (P), OSP calcined temperature (T), Ni(II) concentration (C), OSP dose (D), and contact time (t). The results show that their percentage contribution in descending order is P (64.3%) > T (18.9%) > C (8.8%) > D (5.1%) > t (1.7%). The optimum condition is pH of 10 and OSP calcined temperature of 900 °C. Under the optimum condition, the Ni(II) can be removed almost completely; the higher the pH, the more the precipitation; the higher the calcined temperature, the more the adsorption. The latter is due to the large number of porosities created at the calcination temperature of 900 °C. The porosities generate a large amount of cavities which significantly increase the surface area for adsorption. A multiple linear regression equation obtained to correlate Ni(II) removal with the controllable factors is: Ni(II) removal(%) = 10.35 × P + 0.045 × T - 1.29 × C + 19.33 × D + 0.09 × t - 59.83. This equation predicts Ni(II) removal well and can be used for estimating Ni(II) removal during the design stage of Ni(II) removal by calcined OSP. Thus, OSP can be used to remove nickel effectively and the formula for removal prediction is developed for practical applications.

  19. Dye Aggregation in Ink Jet

    Institute of Scientific and Technical Information of China (English)

    Thomas Paul; Sarfraz Hussain

    2004-01-01

    Dye aggregation has long been recognised as a key factor in performance, and this is no less so in ink jet applications. The aggregation state was shown to be important in many different areas ranging from the use of dyes in photodynamic therapies all the way to colorants for dying of fabrics. Therefore different methods to investigate dye association qualitatively and quantitatively were developed. A simple procedure to study aggregation could be a useful tool to characterise dyes for ink jet printing. It is critically reviewed the methods used to study dye aggregation, and discussed some of the main conclusions. This will be illustrated by examples of ink jet dye aggregation and its study in aqueous and ink systems. The results are used to correlate the solution behaviour of dyes with their print performance.

  20. DRAG ON SUBMICRON NANOPARTICLE AGGREGATES

    Institute of Scientific and Technical Information of China (English)

    F.; Einar; Kruis

    2005-01-01

    A new procedure was developed for estimating the effective collision diameter of an aggregate composed of primary particles of any size. The coagulation coefficient of two oppositely charged particles was measured experimentally and compared with classic Fuchs theory, including a new method to account for particle non-sphericity. A second set of experiments were performed on well-defined nanoparticle aggregates at different stages of sintering, i.e. from the aggregate to the fully sintered stage. Here, electrical mobility was used to characterize the particle drag. The aggregates are being built from two different size-fractionated nanoparticle aerosols, the non-aggregated particles are discarded by an electrofilter and then they are passed through a furnace at concentrations low enough not to induce coagulation.

  1. Optical monitoring of particle aggregates

    Institute of Scientific and Technical Information of China (English)

    John Gregory

    2009-01-01

    Methods for monitoring particle aggregation are briefly reviewed. Most of these techniques are based on some form of light scattering and may be greatly dependent on the optical properties of aggregates, which are not generally known. As fractal aggregates grow larger their density can become very low and this has important practical consequences for light scattering. For instance, the scattering coefficient may be much less than for solid objects, which means that the aggregates can appear much smaller than their actual size by a light transmission method. Also, for low-density objects, a high proportion of the scattered light energy is within a small angle of the incident beam, which may also be relevant for measurements with aggregates.Using the 'turbidity fluctuation' technique as an example, it is shown how the apparent size of hydroxide flocs depends mainly on the included impurity particles, rather than the hydroxide precipitate itself. Results using clay suspensions with hydrolyzing coagulants and under are discussed.

  2. Molecular aggregation of humic substances

    Science.gov (United States)

    Wershaw, R. L.

    1999-01-01

    Humic substances (HS) form molecular aggregates in solution and on mineral surfaces. Elucidation of the mechanism of formation of these aggregates is important for an understanding of the interactions of HS in soils arid natural waters. The HS are formed mainly by enzymatic depolymerization and oxidation of plant biopolymers. These reactions transform the aromatic and lipid plant components into amphiphilic molecules, that is, molecules that consist of separate hydrophobic (nonpolar) and hydrophilic (polar) parts. The nonpolar parts of the molecules are composed of relatively unaltered segments of plant polymers and the polar parts of carboxylic acid groups. These amphiphiles form membrane-like aggregates on mineral surfaces and micelle-like aggregates in solution. The exterior surfaces of these aggregates are hydrophilic, and the interiors constitute separate hydrophobic liquid-like phases.

  3. 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.

  4. Orthogonal flexible Rydberg aggregates

    CERN Document Server

    Leonhardt, K; Rost, J M

    2015-01-01

    We study the link between atomic motion and exciton transport in flexible Rydberg aggregates, assemblies of highly excited light alkali 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 non-adiabatic 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 non-adiabatic 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 {\\it et al.}, Phys.~Rev.~Lett. {\\bf 113} 223001 (2014)]. In this article we discuss the underlying complex dynamics in detail, characterise the ...

  5. Perspectives on Preference Aggregation.

    Science.gov (United States)

    Regenwetter, Michel

    2009-07-01

    For centuries, the mathematical aggregation of preferences by groups, organizations, or society itself has received keen interdisciplinary attention. Extensive theoretical work in economics and political science throughout the second half of the 20th century has highlighted the idea that competing notions of rational social choice intrinsically contradict each other. This has led some researchers to consider coherent democratic decision making to be a mathematical impossibility. Recent empirical work in psychology qualifies that view. This nontechnical review sketches a quantitative research paradigm for the behavioral investigation of mathematical social choice rules on real ballots, experimental choices, or attitudinal survey data. The article poses a series of open questions. Some classical work sometimes makes assumptions about voter preferences that are descriptively invalid. Do such technical assumptions lead the theory astray? How can empirical work inform the formulation of meaningful theoretical primitives? Classical "impossibility results" leverage the fact that certain desirable mathematical properties logically cannot hold in all conceivable electorates. Do these properties nonetheless hold true in empirical distributions of preferences? Will future behavioral analyses continue to contradict the expectations of established theory? Under what conditions do competing consensus methods yield identical outcomes and why do they do so?

  6. Application of coal-water slurry on the rotary calcining kiln of pedgion magnesium reduction process

    Institute of Scientific and Technical Information of China (English)

    LI Hua-qing; XIE Shui-sheng; LIU Jin-ping; WU Peng-yue; HUANG Guo-jie

    2006-01-01

    Energy saving has been an important concept in modern industry especially to the countries and regions with energy shortage such as China and Japan. Utilization of Coal-Water Slurry (CWS) can improve the burning efficiency of coal and reduce the pollutions of soot, sulfide and the nitride by burning lump coal directly. The CWS is a promising energy saving technique and the effectual substitute of oil. The study on the preparation and application of the CWS has made progresses in many aspects. The present paper studied the basal problems for applying the CWS on the rotary kilns during the calcining-dolomite process in the magnesium factory, summarized the key points for the application process of the CWS and gave the corresponding solutions.

  7. Effect of calcination temperature on phase transformation of HfO{sub 2} nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Tripathi, S. K., E-mail: surya@pu.ac.in [Department of Physics, Center of Advanced Study in Physics, Panjab University, Chandigarh-160 014 (India); Center of Nanoscience and Nanotechnology, Panjab University, Chandigarh-160 014 (India); Kaur, Charanpreet [Center of Nanoscience and Nanotechnology, Panjab University, Chandigarh-160 014 (India); Kaur, Ramneek; Kaur, Jagdish [Department of Physics, Center of Advanced Study in Physics, Panjab University, Chandigarh-160 014 (India)

    2015-08-28

    Oxides nanomaterials exhibit unique physical, chemical and structural properties and motivated a big research that focus in the integration of these materials for various optoelectronic device applications. In present work, hafnium oxide (HfO{sub 2}) nanoparticles (NPs) have been synthesized using precipitation method. Hafnium tetrachloride and sodium hydroxide has been used as starting precursors. Prepared oxide material has been characterized by X-Ray Diffraction (XRD), Fourier Transform Infra-Red (FTIR) and UV-Vis spectroscopy. The phase transformation from amorphous to monoclinic is observed with the increase in calcination temperature from 500 °C and 800 °C. In FTIR spectra, the characteristic bands at ν ∼ 758.53 and 509.57 cm{sup −1} reveals the monoclinic phase of prepared HfO{sub 2} NPs. UV-Vis spectroscopy shows an absorption peak at 204 nm and the bandgap calculated is 6.07 eV.

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

    Science.gov (United States)

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

    2011-01-01

    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.

  9. 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.

  10. 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.

  11. Effect of calcining temperature on electrical and dielectric properties of cadmium stannate

    Energy Technology Data Exchange (ETDEWEB)

    Sawant, V.S.; Shinde, S.S.; Deokate, R.J.; Bhosale, C.H.; Chougule, B.K. [Electrochemical Materials Laboratory, Department of Physics, Shivaji University, Kolhapur 416004 (India); Rajpure, K.Y., E-mail: rajpure@yahoo.com [Electrochemical Materials Laboratory, Department of Physics, Shivaji University, Kolhapur 416004 (India)

    2009-04-15

    The cadmium stannate samples were prepared by chemical co-precipitation method using stannic chloride pentahydrate (SnCl{sub 4}.5H{sub 2}O) and cadmium chloride (CdCl{sub 2}) as precursors by carefully controlling the preparative parameters. The effect of calcining temperature on the phase, microstructure, morphological and electrical properties of cadmium stannate has been investigated. The X-ray diffraction patterns indicate the conversion of rhombohedral to spinel cubic crystal structure and polycrystallinity of the samples. SEM study of Cd{sub 2}SnO{sub 4} sample shows randomly distributed cubic crystals of varying sizes. The dc resistivity was measured as a function of temperature. The dielectric constant and dielectric loss were studied as a function of frequency. To understand the conduction mechanism in the samples AC conductivity was measured.

  12. Characterization of red mud derived from a combined Bayer Process and bauxite calcination method.

    Science.gov (United States)

    Liu, Yong; Lin, Chuxia; Wu, Yonggui

    2007-07-19

    Red mud can be derived from the processing of bauxite using different methods. The chemical and mineralogical composition of the combined Bayer Process and bauxite calcination red mud (BPBCRM) differs markedly from those of the pure Bayer Process red mud (PBPRM). In this study, red mud derived from a combined Bayer Process and bauxite calcination method was characterized. The results show that pH of the red mud decreased with increasing duration of storage time. Na dominated among the soluble cations, but the concentration of soluble Na decreased with increasing duration of storage time as a result of leaching. Cation exchange capacity also decreased with increasing duration of storage time, probably due to a decrease in pH causing a reduction in negatively charged sites on the red mud particles. Ca was the predominant exchangeable cation in the fresh red mud but the concentration of exchangeable Ca markedly decreased in the old red mud, which was dominated by exchangeable Na. The degree of crystallization and thermal stability of the red mud increased with increasing duration of storage. The acid neutralizing capacity of red mud obtained from this study was about 10 mol kg(-1), which is much greater than the reported values for the pure Bayer Process red mud. Column filtering experiment indicates that the red mud also had a very strong capacity to remove Cu, Zn and Cd from the filtering solution. It is conservatively estimated that the simultaneous removal rates of Cd, Zn and Cu by red mud are over 22,250 mg kg(-1), 22,500 mg kg(-1) and 25,000 mg kg(-1), respectively. The affinity of these metals to the red mud was in the following decreasing order: Cu>Zn>Cd. In general, the fresh red mud retained more heavy metals than the old red mud did.

  13. Surface complexation modeling calculation of Pb(II) adsorption onto the calcined diatomite

    Science.gov (United States)

    Ma, Shu-Cui; Zhang, Ji-Lin; Sun, De-Hui; Liu, Gui-Xia

    2015-12-01

    Removal of noxious heavy metal ions (e.g. Pb(II)) by surface adsorption of minerals (e.g. diatomite) is an important means in the environmental aqueous pollution control. Thus, it is very essential to understand the surface adsorptive behavior and mechanism. In this work, the Pb(II) apparent surface complexation reaction equilibrium constants on the calcined diatomite and distributions of Pb(II) surface species were investigated through modeling calculations of Pb(II) based on diffuse double layer model (DLM) with three amphoteric sites. Batch experiments were used to study the adsorption of Pb(II) onto the calcined diatomite as a function of pH (3.0-7.0) and different ionic strengths (0.05 and 0.1 mol L-1 NaCl) under ambient atmosphere. Adsorption of Pb(II) can be well described by Freundlich isotherm models. The apparent surface complexation equilibrium constants (log K) were obtained by fitting the batch experimental data using the PEST 13.0 together with PHREEQC 3.1.2 codes and there is good agreement between measured and predicted data. Distribution of Pb(II) surface species on the diatomite calculated by PHREEQC 3.1.2 program indicates that the impurity cations (e.g. Al3+, Fe3+, etc.) in the diatomite play a leading role in the Pb(II) adsorption and dominant formation of complexes and additional electrostatic interaction are the main adsorption mechanism of Pb(II) on the diatomite under weak acidic conditions.

  14. 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.

  15. Hydrothermal synthesis of boehmites with various particle sizes and transition to α-Al2O3 powders by calcination

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    Boehmite powders with various particle sizes have been prepared by hydrothermal method and the α-Al2 O3 powders yielded after subsequent calcination have been studied. Dispersive crystalline boehmite powders of 30-100 nm, 0.4-0. 6μm and 1μm in size were obtained respectively by changing the hydrothermal precursors and the pH value of hydrothermal slurry. Calcination of boehmite powders of 30-100 nm at 1250℃ for 1h resulted in the formation of single-phase α-Al2O3,and the products consisted of vermicular particles. The boehmite powders of 0.4-0.6μm were also fully converted to α-Al2O3 at 1250℃, and the products consisted of plate-like particles with the same size of 0. 4-0. 6μm. The boehmite powders of 1μm calcined at 1350℃ for 2h were still composed of a little proportions of transition aluminas besides α-Al2 O3, and the particles sintered severely. The reaction processes for the formation of crystalline boehmites under hydrothermal conditions and α-Al2O3 powders during calcination have been discussed.

  16. Influence of calcination temperature on sol-gel synthesized single-phase bismuth titanate for high dielectric capacitor applications

    Energy Technology Data Exchange (ETDEWEB)

    Thiruramanathan, Pandirengan; Marikani, Arumugam [Mepco Schlenk Engineering College, Tamil Nadu (India). Dept. of Physics; Madhavan, Durairaj [Mepco Schlenk Engineering College, Tamil Nadu (India). Dept. of Chemistry; Bharadwaj, Suresh; Awasthi, Anand Mohan [UGC-DAE Consortium for Scientific Research, Indore (India). Thermodynamics Lab.

    2016-05-15

    An inexpensive sol-gel combustion method using citric acid as fuel has been used to synthesize bismuth titanate, Bi{sub 4}Ti{sub 3}O{sub 12} nanopowders. Thermogravimetric analysis proved that a calcination temperature of 900 C is sufficient for the preparation of single-phase bismuth titanate. X-ray diffraction and Fourier transform infrared spectroscopy are used to examine the influence of calcination temperature on the structural growth of the Bi{sub 4}Ti{sub 3}O{sub 12} nanopowder. The average crystallite size estimated by using the Scherrer method and the Williamson-Hall method was found to increase with calcination temperature. Photoluminescence behavior as a function of calcination temperature was observed at two different excitation wavelengths of 300 nm and 420 nm. The morphology of the particles analyzed using images obtained from field emission scanning electron microscopy displayed irregular, random sized, and spherical-shaped structures. The stoichiometry and purity of the nanopowder are confirmed by energy-dispersive spectroscopy. The broadband dielectric results established the highest dielectric constant (ε{sub r} = 450) for a frequency of 100 Hz achieved with a potential capacitance of 138 pF m{sup -2}. This establishes Bi{sub 4}Ti{sub 3}O{sub 12} as a promising dielectric material for achieving high energy density capacitors for the next-generation passive devices.

  17. Synthesis of titanium dioxide by ultrasound assisted sol-gel technique: effect of calcination and sonication time.

    Science.gov (United States)

    Pinjari, D V; Prasad, Krishnamurthy; Gogate, P R; Mhaske, S T; Pandit, A B

    2015-03-01

    Nanostructured titanium dioxide has been synthesized using both conventional and ultrasound assisted sol-gel technique with an objective of understanding the role of cavitational effects in the synthesis process. The experiments were conducted at a constant calcination temperature of 750 °C and the calcination time was varied from 30 min to 3 h to study the effect of calcination time on the properties of the synthesized TiO₂. The TiO₂ specimens were characterized using X-ray diffraction (XRD) and scanning electron microscopy (SEM). The influence of the sonication time on the phase transformation process from anatase to rutile and also on the crystallite size and percentage crystallinity of the synthesized TiO₂ has also been investigated. It was observed that 100% phase transformation occurred after 3 h of calcination for the ultrasound assisted sol-gel synthesized TiO₂. The study on the phase transformation via variation of sonication time yielded interesting results. It was observed that as the sonication time increased, an initial increase in the rutile content is obtained and beyond optimum sonication time, the rutile content decreased. In general, the ultrasound assisted process results in synthesis of TiO₂ material with higher rutile content as compared to the conventional sol-gel process.

  18. Effect of calcination temperature and reaction conditions on methane partial oxidation using lanthanum-based perovskite as oxygen donor

    Institute of Scientific and Technical Information of China (English)

    DAI Xiaoping; YU Changchun; LI Ranjia; WU Qiong; SHI Kaijiao; HAO Zhengping

    2008-01-01

    We investigated the effect of calcination temperature, reaction temperature, and different amounts of replenished lattice oxygen on the partial oxidation of methane (POM) to synthesis gas using perovskite-type LaFeO3 oxide as oxygen donor instead of gaseous oxygen, which was prepared by the sol-gel method, and the oxides were characterized by XRD, TG/DTA, and BET. The results indicated that the particle size increased with the calcination temperature increasing, while BET and CH4 conversion declined with the calcination temperature increasing using LaFeO3 oxide as oxygen donor in the absence of gaseous oxygen. CO selectivity remained at a high level such as above 92%, and increased slightly as the calcination temperature increased. Exposure of LaFeO3 oxides to methane atmosphere enhanced the oxygen migration of in the bulk with time online owing to the loss of lattice oxygen and reduction of the oxidative stated Fe ion simultaneously. The high reaction temperature was favorable to the migration of oxygen species from the bulk toward the surface for the synthesis gas production with high CO selectivity. The product distribution and evolution for POM by sequential redox reaction was determined by amounts of replenished lattice oxygen with gaseous oxygen. The optimal process should decline the total oxidation of methane, and increase the selectivity of partial oxidation of methane.

  19. Effect of Calcination Temperature on Catalytic Activity and Textual Property of Cu/HMOR Catalysts in Dimethyl Ether Carbonylation Reaction

    Institute of Scientific and Technical Information of China (English)

    Xue Zhang; Yu-ping Li; Song-bai Qiu; Tie-jun Wang; Long-long Ma; Qi Zhang; Ming-yue Ding

    2013-01-01

    The effect of calcination temperature on the catalytic activity for the dimethyl ether (DME) carbonylation into methyl acetate (MA) was investigated over mordenite supported copper (Cu/HMOR) prepared by ion-exchange process.The results showed that the catalytic activity was obviously affected by the calcination temperature.The maximal DME conversion of 97.2% and the MA selectivity of 97.9% were obtained over the Cu/HMOR calcined at 430 ℃ under conditions of 210 ℃,1.5 MPa,and GSHV of 4883 h-1.The obtained Cu/HMOR catalysts were characterized by powder X-ray diffraction,N2 absorption,NH3 temperature program desorption,CO temperature program desorption,and Raman techniques.Proper calcination temperature was effective to promote copper ions migration and diffusion,and led the support HMOR to possess more acid activity sites,which exhibited the complete decomposing of copper nitrate,large surface area and optimum micropore structure,more amount of CO adsorption site and proper amount of weak acid centers.

  20. Dependability in Aggregation by Averaging

    CERN Document Server

    Jesus, Paulo; Almeida, Paulo Sérgio

    2010-01-01

    Aggregation is an important building block of modern distributed applications, allowing the determination of meaningful properties (e.g. network size, total storage capacity, average load, majorities, etc.) that are used to direct the execution of the system. However, the majority of the existing aggregation algorithms exhibit relevant dependability issues, when prospecting their use in real application environments. In this paper, we reveal some dependability issues of aggregation algorithms based on iterative averaging techniques, giving some directions to solve them. This class of algorithms is considered robust (when compared to common tree-based approaches), being independent from the used routing topology and providing an aggregation result at all nodes. However, their robustness is strongly challenged and their correctness often compromised, when changing the assumptions of their working environment to more realistic ones. The correctness of this class of algorithms relies on the maintenance of a funda...

  1. Aggregating and Disaggregating Flexibility Objects

    DEFF Research Database (Denmark)

    Siksnys, Laurynas; Valsomatzis, Emmanouil; Hose, Katja

    2015-01-01

    In many scientific and commercial domains we encounter flexibility objects, i.e., objects with explicit flexibilities in a time and an amount dimension (e.g., energy or product amount). Applications of flexibility objects require novel and efficient techniques capable of handling large amounts...... energy data management and discuss strategies for aggregation and disaggregation of flex-objects while retaining flexibility. This paper further extends these approaches beyond flex-objects originating from energy consumption by additionally considering flex-objects originating from energy production...... and aiming at energy balancing during aggregation. In more detail, this paper considers the complete life cycle of flex-objects: aggregation, disaggregation, associated requirements, efficient incremental computation, and balance aggregation techniques. Extensive experiments based on real-world data from...

  2. 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

  3. Mercury and methylmercury contents in mine-waste calcine, water, and sediment collected from the Palawan Quicksilver mine, Philippines

    Science.gov (United States)

    Gray, J.E.; Greaves, I.A.; Bustos, D.M.; Krabbenhoft, D.P.

    2003-01-01

    The Palawan Quicksilver mine, Philippines, produced about 2,900 t of mercury during mining of cinnabar ore from 1953 to 1976. More than 2,000,000 t of mine-waste calcines (retorted ore) were produced during mining, much of which were used to construct a jetty in nearby Honda Bay. Since 1995, high Hg contents have been found in several people living near the mine, and 21 of these people were treated for mercury poisoning. Samples of mine-waste calcine contain high total Hg concentrations ranging from 43-660 ??g/g, whereas total Hg concentrations in sediment samples collected from a mine pit lake and local stream vary from 3.7-400 ??g/g. Mine water flowing through the calcines is acidic, pH 3.1-4.3, and total Hg concentrations ranging from 18-31 ??g/l in this water significantly exceed the 1.0-??g/l drinking water standard for Hg recommended by the World Health Organization (WHO). Total Hg contents are generally lower in water samples collected from surrounding domestic wells, the mine pit lake, Honda Bay, and the nearby stream, varying from 0.008-1.4 ??g/l. Methylmercury concentrations in water draining mine calcines range from <0.02-1.4 ng/l, but methylmercury is highest in the pit lake water, ranging from 1.7-3.1 ng/l. Mercury methylation at the Palawan mine is similar to or higher than that found in other mercury mines worldwide. Much of the methylmercury generated in Palawan mine-waste calcines and those in Honda Bay is transferred to water, and then to marine fish and seafood. A food source pathway of Hg to humans is most likely in this coastal, high fish-consuming population.

  4. Ash Aggregates in Proximal Settings

    Science.gov (United States)

    Porritt, L. A.; Russell, K.

    2012-12-01

    Ash aggregates are thought to have formed within and been deposited by the eruption column and plume and dilute density currents and their associated ash clouds. Moist, turbulent ash clouds are considered critical to ash aggregate formation by facilitating both collision and adhesion of particles. Consequently, they are most commonly found in distal deposits. Proximal deposits containing ash aggregates are less commonly observed but do occur. Here we describe two occurrences of vent proximal ash aggregate-rich deposits; the first within a kimberlite pipe where coated ash pellets and accretionary lapilli are found within the intra-vent sequence; and the second in a glaciovolcanic setting where cored pellets (armoured lapilli) occur within Diamond Mine, Canada, are the residual deposits within the conduit and vent of the volcano and are characterised by an abundance of ash aggregates. Coated ash pellets are dominant but are followed in abundance by ash pellets, accretionary lapilli and rare cored pellets. The coated ash pellets typically range from 1 - 5 mm in diameter and have core to rim ratios of approximately 10:1. The formation and preservation of these aggregates elucidates the style and nature of the explosive phase of kimberlite eruption at A418 (and other pipes?). First, these pyroclasts dictate the intensity of the kimberlite eruption; it must be energetic enough to cause intense fragmentation of the kimberlite to produce a substantial volume of very fine ash (sustained plume attended by concomitant production of pyroclastic density currents. The size and internal structure of the armoured lapilli provide constraints on the nature of the initial explosive phase of eruption at Kima'Kho. Their proximity to the vent also indicates rapid aggregation within the eruption plume. Within both sequences rapid aggregation of ash particles occurred in proximity to the vent. However, the conditions were substantially different leading to the production of armoured

  5. Global warming impact on the cement and aggregates industries

    Energy Technology Data Exchange (ETDEWEB)

    Davidovits, J. (Cordi-Geopolymere SA, Saint-Quentin (France). Geopolymer Inst.)

    1994-06-01

    CO[sub 2] related energy taxes are focusing essentially on fuel consumption, not on actual CO[sub 2] emission measured at the chimneys. Ordinary Portland cement, used in the aggregates and industries, results from the calcination of limestone and silica. The production of 1 ton of cement directly generates 0.55 tons of chemical-CO[sub 2] and requires the combustion of carbon-fuel to yield an additional 0.40 tons of CO[sub 2]. The 1987 1 billion metric tons world production of cement accounted for 1 billion metric tons of CO[sub 2], i.e., 5% of the 1987 world CO[sub 2] emission. A world-wide freeze of CO[sub 2] emission at the 1990 level as recommended by international institutions, is incompatible with the extremely high cement development needs of less industrialized countries. Present cement production growth ranges from 5% to 16% and suggests that in 25 years from now, world cement CO[sub 2] emissions could equal 3,500 million tons. Eco-taxes when applied would have a spectacular impact on traditional Portland cement based aggregates industries. Taxation based only on fuel consumption would lead to a cement price increase of 20%, whereas taxation based on actual CO[sub 2] emission would multiply cement price by 1.5 to 2. A 25--30% minor reduction of CO[sub 2] emissions may be achieved through the blending of Portland cement with replacement materials such as coal-fly ash and iron blast furnace slag.

  6. 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…

  7. 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....

  8. 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...

  9. An exact approach for aggregated formulations

    DEFF Research Database (Denmark)

    Gamst, Mette; Spoorendonk, Simon; Røpke, Stefan

    optimality cannot be guaranteed by branching on aggregated variables. We present a generic exact solution method to remedy the drawbacks of aggregation. It combines the original and aggregated formulations and applies Benders' decomposition. We apply the method to the Split Delivery Vehicle Routing Problem.......Aggregating formulations is a powerful approach for problems to take on tractable forms. Aggregation may lead to loss of information, i.e. the aggregated formulation may be an approximation of the original problem. In branch-and-bound context, aggregation can also complicate branching, e.g. when...

  10. Infrared Spectral Analysis for Calcined Borax%煅硼砂的红外光谱分析与评价

    Institute of Scientific and Technical Information of China (English)

    赵翠; 任丽莉; 王栋; 周平; 张倩; 王伯涛

    2011-01-01

    对煅硼砂饮片进行质量评价.以18个不同含水量的煅硼砂样品为研究对象,使用傅里叶红外光谱仪采集样品的红外吸收图谱,并对红外图谱进行分析,再根据分析结果对煅硼砂饮片进行质量评价.发现煅硼砂的红外光谱主要包括OH、BO3-3和BO5-4振动引起的三个吸收带,OH振动吸收带的位置及宽度依赖于含水量的高低,含水量越高,吸收带越宽;BO3-3及BO5-4振动吸收带的数目也取决于含水量的高低,含水量越高,氢键作用越强,B原子的对称性越低,红外吸收峰数目越多.结论:因含水量与煅硼砂样品的质量直接相关,故红外光谱法可为煅硼砂的质量分析与评价研究提供一种灵敏、客观的方法和手段.%To valuate the quality of calcined borax which is sold in the market, 18 samples of calcined borax were studied using the Fourier transform infrared, and samples with different water content were selected and analyzed. Then, the results of analysis were used to evaluate the quality of calcined borax. Results show that the infrared spectra of calcined borax include OH vibration, BO3-3 vibration and BQ5-4 vibration absorption bands. The position and width of OH vibration absorption band depend on the level of water content, and the more the water content, the wider the absorption band. The number of BO3-3 vibration and BO5-4 vibration bands also depend on the level of water content, and the more the water content, and the stronger the hydrogen bond and the lower the symmetry of B atoms, the more the number of infrared absorption peaks. It was concluded that because the quality of calcined borax has direct correlation with water content, the infrared spectroscopy is an express and objective approach to quality analysis and evaluation of calcined borax.

  11. Development of a high energy efficient pressure calciner. Final report, June 1, 1994--July 31, 1997

    Energy Technology Data Exchange (ETDEWEB)

    Bush, J.F.

    1997-12-18

    During the life of this contract, the design, procurement, and construction of a pilot, self-fluidizing, pressure calciner for the production of smelting grade alumina was completed. Initial operating characteristics were determined, and the first half of the first DOX was completed. A design capacity of at least 100 kg/hr of product had been chosen to insure a 100:1 maximum scale-up ratio for the semi-commercial unit. Detailed numerical analysis was made for the heat exchanger design to set the active tube length at 8.5 m (28 ft). The instrumentation and data logging system was designed to obtain the detailed engineering parameters for design of the semi-commercial unit. The pressure feed, discharge, and burner systems were chosen from existing commercial designs to reduce the development work required. Auxiliary equipment, steam condenser, cooling tower, and product cooler, were chosen to simplify operation during the experimental program. Self-fluidizing capabilities were determined to exist both from temperature profiles and heat transfer coefficient calculations.

  12. 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)

  13. 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.

  14. 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.

  15. Strength of Limestone-based Non-calcined Cement and its Properties

    Institute of Scientific and Technical Information of China (English)

    LIN Zongshou; ZHAO Qian

    2009-01-01

    A new type of cement was prepared with ground limestone powder,blastfurnace slag,steel slag and gypsum without calcination.The fraction of ground limestone powder in the cement was as high as 40 wt%-60 wt%without Portland clinker.All of its physical properties can meet the requirements of masonry cement standards.The impact of limestone content on physical properties of the cement and determined its impact on law was investigated.The steel slag can excit the aquation activity of this cement effectively,and the influence of its quantity on the strength of the materials was studied,which shows that the optimum quantity of mixing is 10%.By way of changing the different content of the lime stone by quartzy sample,the law of the compression strength and the PH value was determined,confirming that the lime stone can promote the early aquation of the slag and improve the early strength.The main hydration product of this cement is calcium aluminate hydrate, ettringite and calcium silicate hydrate,as indicated by XRD and SEM analysis.

  16. Kinetics of Hg(II) adsorption and desorption in calcined mussel shells.

    Science.gov (United States)

    Peña-Rodríguez, Susana; Fernández-Calviño, David; Nóvoa-Muñoz, Juan Carlos; Arias-Estévez, Manuel; Núñez-Delgado, Avelino; Fernández-Sanjurjo, María José; Alvarez-Rodríguez, Esperanza

    2010-08-15

    The potential use of calcined mussel shells to purify water contaminated with mercury was evaluated. The Hg(II) adsorption and desorption kinetics were studied in batch-type and stirred-flow chamber experiments. The adsorption/desorption experiments revealed some differences between the batches of shells used. The batch of shells that displayed the greatest capacity to adsorb Hg(II), via a highly irreversible reaction, also contained more Fe and Al than the other batches. The results of the stirred-flow chamber experiments indicated a high degree of irreversibility in the process of Hg(II) adsorption in the mussel shell, and that Hg(II) was rapidly retained. The results of these experiments also revealed that the efficiency of depuration differed depending on the length of time that the system was used: when the system was operated for 55 min, depurating 162 mL of inflowing water g(-1) mussel shell, a 90% reduction in the initial concentration of Hg(II) was obtained; use of the system for 90 min, depurating 265 mL water g(-1) mussel shell, produced a 75% reduction in the initial Hg(II), and use of the system for 162.5 min, depurating 487 mL of water g(-1) mussel shell, resulted in a 50% reduction in the initial Hg(II).

  17. Mineral Phase and Physical Properties of Red Mud Calcined at Different Temperatures

    Directory of Open Access Journals (Sweden)

    Chuan-sheng Wu

    2012-01-01

    Full Text Available Different characterizations were carried out on red mud uncalcined and samples calcined in the range of 100°C–1400°C. In the present paper, the phase composition and structural transition of red mud heated from room temperature are indicated by XRD, TG-DTA, and SEM techniques. The mean particle diameter, density, and bond strength of these samples also have been investigated. The results indicate the decomposition of gibbsite into Al2O3 and H2O between 300°C and 550°C and calcite into CaO and CO2 in the interval of 600–800°C. Tricalcium aluminate and gehlenite are formed in the range of 800–900°C. Combined with the SEM images, the results of physical property testing show that the particle size and the strength each has a continuous rise during the heat treatment from 150°C to 1350°C. But the value of density will undergo a little drop before 450°C and then increases to a higher value at the temperature of 1200°C. These obtained results provide an important base for the further studies of comprehensive utilization of red mud.

  18. [XPS study on the influence of calcination conditions to cerium ion valence].

    Science.gov (United States)

    Mei, Yan; Yan, Jian-ping; Nie, Zuo-ren

    2010-01-01

    For the system of Ce(NO3)2.6H2O and urea solution during homogeneous precipitation method, X-ray diffraction (XRD), infrared spectrum (IR) and especially X-ray photoelectron spectroscopy (XPS) were used to study and characterize the product structure, variety of cerium ion valence, compound surface character and kernel electronic configurations. The results of XRD and IR showed that calcination temperature had a great effect on the cerium ion valence. The products are orthorhombic Ce2 O(CO3)2.H2O with valence III by using homogeneous precipitation method directly. When heated from the temperature 200 degrees C to 250 degrees C, the product of CeO(CO3)2.H2O with valence VI was finally changed into stable CeO2 with valence IV. XPS was used to study the surface character and kernel electronic configurations of the three different compounds through fine scanning of O(1s), Ce(3d) and Ce(4d) apices, and the results approved that the compounds with different valences are caused by the different valence electronic configurations of the products.

  19. 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.

  20. 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.

  1. 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.

  2. 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.

  3. Effect of calcining temperature and time on the characteristics of Sb-doped SnO2 nanoparticles synthesized by the sol-gel method

    Institute of Scientific and Technical Information of China (English)

    Xiaohua Zhong; Baoping Yang; Xiaoliang Zhang; Junhong Jia; Gewen Yi

    2012-01-01

    Spherical Sb-doped SnO2 (ATO) nanoparticles were synthesized by the sol-gel route,employing SnCl4·5H2O and SbCl3 as precursors in an ethanol solution.The influences of the calcining temperature and calcining time on the crystallite size,crystallinity,lattice parameters,lattice distortion ratio and the resistivity of the ATO nanoparticles were synthetically investigated.The results suggested that the ATO nanoparticles were crystallized in a tetragonal cassiterite structure of SnO2 with a highly (110)-plane-preferred orientation.The calcining temperature had a dominating effect on the crystallite size,crystallinity,lattice distortion ratios and resistivity of the ATO.As the calcining temperature increased,the average crystallite size increased,the crystallinity was promoted accompanied by a decrease in the lattice distortion ratio and a corresponding decrease in the resistivity of the ATO.X-ray diffraction (XRD) and Fourier transform infrared spectrophotometer (FTIR) analysis revealed that Sb ions could not entirely supplant the Sn ions in the SnO2 lattice for a calcining time of less than 0.5 h,even at a calcining temperature of 1000℃.The ATO nanoparticles calcined at 1000℃ for 3.0h possessed the lowest resistivity of 10.18Ωcm.

  4. Erythrocyte aggregation: Basic aspects and clinical importance

    OpenAIRE

    Oğuz K. Başkurt; Meiselman, Herbert J.

    2013-01-01

    Red blood cells (RBC) aggregate to form two- and three-dimensional structures when suspended in aqueous solutions containing large plasma proteins or polymers; this aggregation is reversible and shear dependent (i.e., dispersed at high shear and reformed at low or stasis). The extent of aggregation is the main determinant of low shear blood viscosity, thus predicting an inverse relationship between aggregation and in vivo blood flow. However, the effects of aggregation on hemodynamic mechanis...

  5. Molecular Aggregation in Disodium Cromoglycate

    Science.gov (United States)

    Singh, Gautam; Agra-Kooijman, D.; Collings, P. J.; Kumar, Satyendra

    2012-02-01

    Details of molecular aggregation in the mesophases of the anti-asthmatic drug disodium cromoglycate (DSCG) have been studied using x-ray synchrotron scattering. The results show two reflections, one at wide angles corresponding to π-π stacking (3.32 å) of molecules, and the other at small angles which is perpendicular to the direction of molecular stacking and corresponds to the distance between the molecular aggregates. The latter varies from 35 - 41 å in the nematic (N) phase and 27 -- 32 å in the columnar (M) phase. The temperature evolution of the stack height, positional order correlations in the lateral direction, and orientation order parameter were determined in the N, M, and biphasic regions. The structure of the N and M phases and the nature of the molecular aggregation, together with their dependence on temperature and concentration, will be presented.

  6. 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

  7. Effects of Calcination Temperature on the Acidity and Catalytic Performances of HZSM-5 Zeolite Catalysts for the Catalytic Cracking of n-Butane

    Institute of Scientific and Technical Information of China (English)

    Jiangyin Lu; Zhen Zhao; Chunming Xu; Aijun Duan; Pu Zhang

    2005-01-01

    The acidic modulations of a series of HZSM-5 catalysts were successfully made by calcination at different treatment temperatures, i.e. 500, 600, 650, 700 and 800 ℃, respectively. The results indicated that the total acid amounts, their density and the amount of B-type acid of HZSM-5 catalysts rapidly decreased, while the amounts of L-type acid had almost no change and thus the ratio of L/B was obviously enhanced with the increase of calcination temperature (excluding 800 ℃). The catalytic performances of modified HZSM-5 catalysts for the cracking of n-butane were also investigated. The main properties of these catalysts were characterized by means of XRD, N2 adsorption at low temperature, NH3-TPD, FTIR of pyridine adsorption and BET surface area measurements. The results showed that HZSM-5 zeolite pretreated at 800 ℃ had very low catalytic activity for n-butane cracking. In the calcination temperature range of 500-700 ℃, the total selectivity to olefins, propylene and butene were increased with the increase of calcination temperature, while, the selectivity for arene decreased with the calcination temperature.The HZSM-5 zeolite calcined at 700 ℃ produced light olefins with high yield, at the reaction temperature of 650 ℃ the yields of total olefins and ethylene were 52.8% and 29.4%, respectively. Besides, the more important role is that high calcination temperature treatment improved the duration stability of HZSM-5zeolites. The effect of calcination temperature on the physico-chemical properties and catalytic performance of HZSM-5 for cracking of n-butane was explored. It was found that the calcination temperature had large effects on the surface area, crystallinity and acid properties of HZSM-5 catalyst, which further affected the catalytic performance for n-butane cracking.

  8. 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

  9. 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...

  10. Balancing energy flexibilities through aggregation

    DEFF Research Database (Denmark)

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

    2014-01-01

    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...... 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...

  11. Effect of calcination method on the product distribution from catalytic degradation of polystyrene in the presence of 1% Pd/Al2O3 catalysts

    Science.gov (United States)

    Ramli, Anita; Kun, Lim Sheo; Kait, Chong Fai; Yahya, Noorhana; Daud, Hanita

    2012-11-01

    Incipient wetness impregnation method was used to prepare 1% Pd/Al2O3 catalyst which was calcined at 500 °C for 16 hr as well as in a domestic microwave at 650W for 5 and 10 min. These catalysts were tested in the catalytic degradation of polystyrene (PS) into liquid fuels at catalyst to PS ratio of 0.2 (w/w). The organic liquid product (OLP) collected was analysed using Gas Chromatography (GC). Results show that the conventional calcined catalyst gives petrol as the main product while kerosene was the main product for the microwave calcined catalysts.

  12. Influence of calcination atmosphere on photocatalytic reactivity of K2La2Ti3O10 for water splitting

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The layered perovskite type oxide K2La2Ti3O10 powders were prepared under air, Ar and H2 calcination atmospheres by sol-gel method and characterized by X-ray diffractometry, UV-Vis diffuse reflectance and X-ray photoelectron spectroscopy. The influence of the calcination atmosphere on the photocatalytic reactivity of K2La2Ti3O10 for hydrogen production was investigated.The photocatalytic reactivity of K2La2Ti3O10 prepared under air, Ar and H2 atmospheres was compared with that prepared under ultraviolet and visible light radiation using I- as electronic donor. The results show that K2La2Ti3O10 prepared under Ar and H2atmospheres has higher photocatalytic activity for hydrogen production than that prepared under air atmosphere. The hydrogen

  13. 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.

  14. Studies of the Catalytic Activity and Deactivation of Calcined Layered Double Hydroxides in the Reaction of Ethanol with Propylene Oxide

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The reaction of ethanol with propylene oxide over calcined layered double hydroxides(CLDH) was investigated. The results show that CLDH has a good activity and a good selectivity, but the activity and the selectivity of CLDH decrease when CLDH reforms LDH- the so called "memory effect". The influence of the "memory effect" on the CLDH returning to LDH was studied by the hydration reaction. It is shown that the "memory effect" is not complete, and the decreases of the Mg/Al molar ratio of LDH and the crystallite size due to the increase of the hydration reaction time result in the drop of the activity and the selectivity.Keyworcds Ethanol, Propylene oxide, Calcined layered double hydroxide, "Memory effect", Hydration

  15. 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.

  16. 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

    Cement industry is one of the major industrial emitters of greenhouse gases, generating 5-7% of the total anthropogenic CO2 emissions. Consequently, use of supplementary cementitious materials (SCM) to replace part of the CO2-intensive cement clinker is an attractive way to mitigate CO2 emissions...... from cement industry. SCMs based on industrial byproducts like fly ashes and slags are subject to availability problems. Yet clays are the most ubiquitous material on earth's crust. Thus, properly calcined clays are a very promising candidate for SCMs to produce green cements. Calcination...... PROcess Modeling System) software, which is suspended during the project due to the adjustment made by the project consortium. The model results from both C++ and gPROMS software show good similarity. Various experiments have been performed to derive key kinetic data, to collect data from a gas suspension...

  17. Effect of calcination temperature on the structural and electrical properties of cobalt ferrite synthesized by combustion method

    Energy Technology Data Exchange (ETDEWEB)

    Khandekar, M.S. [Ferrite Materials Laboratory, Department of Physics, Solapur University, Solapur 413255, MS (India); Kambale, R.C. [Composite Materials Laboratory, Department of Physics, Shivaji University, Kolhapur 416004, MS (India); Patil, J.Y. [Ferrite Materials Laboratory, Department of Physics, Solapur University, Solapur 413255, MS (India); Kolekar, Y.D. [Department of Physics, University of Pune, Ganeshkhind, Pune 411007, MS (India); Suryavanshi, S.S., E-mail: sssuryavanshi@rediffmail.com [Ferrite Materials Laboratory, Department of Physics, Solapur University, Solapur 413255, MS (India)

    2011-02-03

    Research highlights: > The CoFe{sub 2}O{sub 4} nanoparticles were prepared by autocombustion method with hexamine as a fuel. > TGA measurements confirm the stable phase formation of the phase above 700 deg. C. > Effect of calcination temperature on the structural and electrical properties of cobalt ferrite was investigated. > The particle size strongly affects the electrical property. > ac conductivity measurement reveals the conduction in the present phase is of small polaron type. - Abstract: In this paper, the structural and electrical properties of cobalt ferrite synthesized by combustion route with hexamine as a fuel are reported for the first time. Thermogravemetric analysis (TGA) confirm the stable phase formation of the phase above 700 deg. C. Structural characterizations of all the samples were carried out by X-ray diffraction (XRD) technique. It reveals an increase in the particle size with the calcination temperature (i.e. 700, 800 and 900 deg. C). Infrared (IR) spectroscopy confirms the presence of tetrahedral and octahedral group complexes within the spinel lattice. DC resistivity as function of temperature indicates that all the samples obey the semiconducting behavior and it decreases with calcination temperature. The variation of dielectric constant ({epsilon}{sub r}) and ac conductivity ({sigma}{sub ac}), for all the samples have been studied as a function of applied frequency in the range from 20 Hz to 1 MHz. The dielectric constant increases with the calcination temperature and all the samples exhibit usual dielectric dispersion which is due to the Maxwell-Wagner-type interfacial polarization. The ac conductivity measurement suggests that the conduction is due to small polaron hopping.

  18. Tailoring the Microstructure of a Solid Oxide Fuel Cell Anode Support by Calcination and Milling of YSZ

    Science.gov (United States)

    Hanifi, Amir Reza; Laguna-Bercero, Miguel A.; Sandhu, Navjot Kaur; Etsell, Thomas H.; Sarkar, Partha

    2016-06-01

    In this study, the effects of calcination and milling of 8YSZ (8 mol% yttria stabilized zirconia) used in the nickel-YSZ anode on the performance of anode supported tubular fuel cells were investigated. For this purpose, two different types of cells were prepared based on a Ni-YSZ/YSZ/Nd2NiO4+δ-YSZ configuration. For the anode preparation, a suspension was prepared by mixing NiO and YSZ in a ratio of 65:35 wt% (Ni:YSZ 50:50 vol.%) with 30 vol.% graphite as the pore former. As received Tosoh YSZ or its calcined form (heated at 1500 °C for 3 hours) was used in the anode support as the YSZ source. Electrochemical results showed that optimization of the fuel electrode microstructure is essential for the optimal distribution of gas within the support of the cell, especially under electrolysis operation where the performance for an optimized cell (calcined YSZ) was enhanced by a factor of two. In comparison with a standard cell (containing as received YSZ), at 1.5 V and 800 °C the measured current density was -1380 mA cm-2 and -690 mA cm-2 for the cells containing calcined and as received YSZ, respectively. The present study suggests that the anode porosity for improved cell performance under SOEC is more critical than SOFC mode due to more complex gas diffusion under electrolysis mode where large amount of steam needs to be transfered into the cell.

  19. 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.

  20. 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.

  1. Process for capturing CO2 arising from the calcination of the CaCO3 used in cement manufacture.

    Science.gov (United States)

    Rodríguez, N; Alonso, M; Grasa, G; Abanades, J Carlos

    2008-09-15

    This paper outlines a new CaCO3 calcination method for producing a stream of CO2 (suitable for permanent geological storage after purification and compression). The process is based on the use of very hot CaO particles (T >1000 degrees C) to transfer heat from a circulating fluidized bed combustor (CFBC) to a calciner (fluidized with CO2 and/or steam). Since the fluidized bed combustor and calciner have separate atmospheres, the CO2 resulting from the decomposition of CaCO3 can be captured, while the CO2 generated in the combustion of the fuel in air is emitted to the atmosphere. We demonstrate that with this system it is possible to reduce the CO2 emissions of a cement plant by around 60%. Furthermore, since the key pieces of equipment are similar to the commercial CFBCs used in power generation plants, it is possible to establish the additional investment required for the system and to estimate the cost per ton of CO2 avoided for this process to be about 19 $/tCO2 avoided.

  2. SMALL-SCALE TESTING OF PLUTONIUM (IV) OXALATE PRECIPITATION AND CALCINATION TO PLUTONIUM OXIDE TO SUPPORT THE MOX FEED MISSION

    Energy Technology Data Exchange (ETDEWEB)

    Crowder, M.; Pierce, R.; Scogin, J.; Daniel, G.; King, W.

    2012-06-25

    The H-Canyon facility will be used to dissolve Pu metal for subsequent purification and conversion to plutonium dioxide (PuO{sub 2}) using Phase II of HB-Line. To support the new mission, SRNL conducted a series of experiments to produce calcined plutonium (Pu) oxide and measure the physical properties and water adsorption of that material. This data will help define the process operating conditions and material handling steps for HB-Line. An anion exchange column experiment produced 1.4 L of a purified 52.6 g/L Pu solution. Over the next nine weeks, seven Pu(IV) oxalate precipitations were performed using the same stock Pu solution, with precipitator feed acidities ranging from 0.77 M to 3.0 M nitric acid and digestion times ranging from 5 to 30 minutes. Analysis of precipitator filtrate solutions showed Pu losses below 1% for all precipitations. The four larger precipitation batches matched the target oxalic acid addition time of 44 minutes within 4 minutes. The three smaller precipitation batches focused on evaluation of digestion time and the oxalic acid addition step ranged from 25-34 minutes because of pump limitations in the low flow range. Following the precipitations, 22 calcinations were performed in the range of 610-690 C, with the largest number of samples calcined at either 650 or 635 C. Characterization of the resulting PuO{sub 2} batches showed specific surface areas in the range of 5-14 m{sup 2}/g, with 16 of the 22 samples in the range of 5-10 m2/g. For samples analyzed with typical handling (exposed to ambient air for 15-45 minutes with relative humidities of 20-55%), the moisture content as measured by Mass Spectrometry ranged from 0.15 to 0.45 wt % and the total mass loss at 1000 C, as measured by TGA, ranged from 0.21 to 0.58 wt %. For the samples calcined between 635 and 650 C, the moisture content without extended exposure ranged from 0.20 to 0.38 wt %, and the TGA mass loss ranged from 0.26 to 0.46 wt %. Of these latter samples, the samples

  3. The decrease of carbonation efficiency of CaO along calcination-carbonation cycles: Experiments and modelling

    Energy Technology Data Exchange (ETDEWEB)

    Bouquet, E.; Leyssens, G.; Schonnenbeck, C.; Gilot, P. [Laboratoire de Gestion des Risques et Environnement, Mulhouse (France)

    2009-05-15

    Successive calcination-carbonation cycles, using CaO as sorbent, have been performed either in a classical fixed bed reactor or using a thermogravimetric analyser. Significant differences in carbonation efficiencies were obtained, possibly due to different conditions prevailing for CaO sintering during the calcination stage. The effect of the presence of CO{sub 2} on sintering was confirmed. A simple model of the decay of the carbonation capacity along cycles based on the specific surface area of non-sintered micrograins of CaO is able to predict the decrease of the extent of conversion obtained after 40 carbonations along calcination-carbonation cycles. The asymptotic extent of conversion is obtained when all the micrograins present within a grain are sintered. A detailed model of the carbonation shows that the voids present between the micrograins are filled up by carbonate when a critical thickness of the carbonate layer around each micrograin reaches 43 nm. Then, carbonation becomes controlled by diffusion at the scale of the whole grain, with the CO{sub 2} diffusion coefficient decreasing (at 650 {sup o}C) from 2 x 10{sup -12} to 6.5 x 10{sup -14} m{sup 2}/s as carbonation proceeds from 50% conversion to 76% (first cycle). This scale change for diffusion is responsible for the drastic decrease of the carbonation rate after the voids between micrograins are filled up.

  4. 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.

  5. Mesoporous Titania Powders: The Role of Precursors, Ligand Addition and Calcination Rate on Their Morphology, Crystalline Structure and Photocatalytic Activity

    Directory of Open Access Journals (Sweden)

    Elisabetta Masolo

    2014-07-01

    Full Text Available We evaluate the influence of the use of different titania precursors, calcination rate, and ligand addition on the morphology, texture and phase content of synthesized mesoporous titania samples, parameters which, in turn, can play a key role in titania photocatalytic performances. The powders, obtained through the evaporation-induced self-assembly method, are characterized by means of ex situ X-Ray Powder Diffraction (XRPD measurements, N2 physisorption isotherms and transmission electron microscopy. The precursors are selected basing on two different approaches: the acid-base pair, using TiCl4 and Ti(OBu4, and a more classic route with Ti(OiPr4 and HCl. For both precursors, different specimens were prepared by resorting to different calcination rates and with and without the addition of acetylacetone, that creates coordinated species with lower hydrolysis rates, and with different calcination rates. Each sample was employed as photoanode and tested in the water splitting reaction by recording I-V curves and comparing the results with commercial P25 powders. The complex data framework suggests that a narrow pore size distribution, due to the use of acetylacetone, plays a major role in the photoactivity, leading to a current density value higher than that of P25.

  6. Synthesis of type A zeolite from calcinated kaolin; Sintese de zeolita tipo A a partir de caulim calcinado

    Energy Technology Data Exchange (ETDEWEB)

    Rodrigues, E.C.; Neves, R.F.; Souza, J.A.S. [Universidade Federal do Para (PPEQ/UFPA), Abaetetuba, PA (Brazil). Instituto de Engenharia Quimica. Programa de Pos-Graduacao; Moraes, C.G.; Macedo, E.N., E-mail: mersone7@yahoo.com.br [Universidade Federal do Para (PRODERNA/UFPA), Abaetetuba, PA (Brazil). Programa de Pos-Graduacao em Engenharia de Recursos Naturais da Amazonia

    2011-07-01

    The mineral production has caused great concern in environmental and industrial scenario due to the effects caused to the environment. The industries of processing kaolin for paper are important economically for the state of Para, but produce huge quantities of tailings, which depend on large areas to be stocked. This material is rich in silico-aluminates can be recycled and used as raw material for other industries. The objective is to synthesize zeolite A at different temperatures of calcination and synthesis. The starting materials and synthesis of zeolite A have been identified and characterized through analysis of X-ray diffraction (DRX) and scanning electron microscopy (MEV). The synthesis process of zeolite A, using as source of silica and the aluminum metakaolin, which was calcined at temperatures of 700 ° C and 800 ° C for 2 hours of landing in a burning furnace type muffle. Observed in relation to the calcination of kaolin as the main phase, the metakaolin. This is just a removal of water from its structure, so we opted for the lower temperature, less energy consumption. The synthesis process of zeolite A, produced good results for the formation of zeolites type A, which were characterized with high purities. (author)

  7. Quantitative investigations of aggregate systems.

    Science.gov (United States)

    Rai, D K; Beaucage, G; Jonah, E O; Britton, D T; Sukumaran, S; Chopra, S; Gonfa, G Goro; Härting, M

    2012-07-28

    Nanomaterials with disordered, ramified structure are increasingly being used for applications where low cost and enhanced performance are desired. A particular example is the use in printed electronics of inorganic conducting and semiconducting nanoparticles. The electrical, as well as other physical properties depend on the arrangement and connectivity of the particles in such aggregate systems. Quantification of aggregate structure and development of structure/property relationships is difficult and progress in the application of these materials in electronics has mainly been empirical. In this paper, a scaling model is used to parameterize the structure of printed electronic layers. This model has chiefly been applied to polymers but surprisingly it shows applicability to these nanolayers. Disordered structures of silicon nanoparticles forming aggregates are investigated using small angle x-ray scattering coupled with the scaling model. It is expected that predictions using these structural parameters can be made for electrical properties. The approach may have wide use in understanding and designing nano-aggregates for electronic devices.

  8. Diversity, intent, and aggregated search

    NARCIS (Netherlands)

    M. de Rijke

    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 que

  9. Cyclosporine A enhances platelet aggregation.

    Science.gov (United States)

    Grace, A A; Barradas, M A; Mikhailidis, D P; Jeremy, J Y; Moorhead, J F; Sweny, P; Dandona, P

    1987-12-01

    In view of the reported increase in thromboembolic episodes following cyclosporine A (CyA) therapy, the effect of this drug on platelet aggregation and thromboxane A2 release was investigated. The addition of CyA, at therapeutic concentrations to platelet rich plasma from normal subjects in vitro was found to increase aggregation in response to adrenaline, collagen and ADP. Ingestion of CyA by healthy volunteers was also associated with enhanced platelet aggregation. The CyA-mediated enhancement of aggregation was further enhanced by the addition in vitro of therapeutic concentrations of heparin. Platelets from renal allograft recipients treated with CyA also showed hyperaggregability and increased thromboxane A2 release, which were most marked at "peak" plasma CyA concentration and less so at "trough" concentrations. Platelet hyperaggregability in renal allograft patients on long-term CyA therapy tended to revert towards normal following the replacement of CyA with azathioprine. Hypertensive patients with renal allografts on nifedipine therapy had normal platelet function and thromboxane release in spite of CyA therapy. These observations suggest that CyA-mediated platelet activation may contribute to the pathogenesis of the thromboembolic phenomena associated with the use of this drug. The increased release of thromboxane A2 (a vasoconstrictor) may also play a role in mediating CyA-related nephrotoxicity.

  10. Sequence-dependent internalization of aggregating peptides.

    Science.gov (United States)

    Couceiro, José R; Gallardo, Rodrigo; De Smet, Frederik; De Baets, Greet; Baatsen, Pieter; Annaert, Wim; Roose, Kenny; Saelens, Xavier; Schymkowitz, Joost; Rousseau, Frederic

    2015-01-02

    Recently, a number of aggregation disease polypeptides have been shown to spread from cell to cell, thereby displaying prionoid behavior. Studying aggregate internalization, however, is often hampered by the complex kinetics of the aggregation process, resulting in the concomitant uptake of aggregates of different sizes by competing mechanisms, which makes it difficult to isolate pathway-specific responses to aggregates. We designed synthetic aggregating peptides bearing different aggregation propensities with the aim of producing modes of uptake that are sufficiently distinct to differentially analyze the cellular response to internalization. We found that small acidic aggregates (≤500 nm in diameter) were taken up by nonspecific endocytosis as part of the fluid phase and traveled through the endosomal compartment to lysosomes. By contrast, bigger basic aggregates (>1 μm) were taken up through a mechanism dependent on cytoskeletal reorganization and membrane remodeling with the morphological hallmarks of phagocytosis. Importantly, the properties of these aggregates determined not only the mechanism of internalization but also the involvement of the proteostatic machinery (the assembly of interconnected networks that control the biogenesis, folding, trafficking, and degradation of proteins) in the process; whereas the internalization of small acidic aggregates is HSF1-independent, the uptake of larger basic aggregates was HSF1-dependent, requiring Hsp70. Our results show that the biophysical properties of aggregates determine both their mechanism of internalization and proteostatic response. It remains to be seen whether these differences in cellular response contribute to the particular role of specific aggregated proteins in disease.

  11. Low Temperature Synthesis of Single-crystal Alpha Alumina Platelets by Calcining Bayerite and Potassium Sulfate

    Institute of Scientific and Technical Information of China (English)

    Xinghua Su; Jiangong Li

    2011-01-01

    Single-crystal alpha alumina (α-Al2O3) platelets were synthesized by calcining a powder mixture of bayerite (α-AI(OH)3) and potassium sulfate (K2SO4) at 900℃. The crystalline phase evolutions and morphologies of the samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The synthesized samples mainly consisted of single-crystal α-Al2O3 platelets with a diameter of 0.5-1.5 μm and a thickness of 50-150 nm. Moreover, with 3, 5, and 8 wt% (referred to the obtained alumina) α-Al2O3 seeds adding into the powder mixture of bayerite and potassium sulfate, the average diameter of α-Al2O3 platelets can be reduced to 450, 240, and 220 nm, respectively. It is found that the sequence of the phase transformation is the bayerite (α-Al(OH)3) → boehmite (γ-AIOOH) →γ-Al2O3 → α-Al2O3. Further analysis indicated that K2SO4 can promote the phase transformation from α-Al2O3 to α-Al2O3 and the formation of single-crystal α-Al2O3 platelets might be attributed to the liquid phase K3AI(SO4)3.

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

    Energy Technology Data Exchange (ETDEWEB)

    Yoon, Seyoon [School of Engineering, Kings College, University of Aberdeen, Aberdeen AB24 3UE (United Kingdom); Moon, Juhyuk, E-mail: juhyuk.moon@stonybrook.edu [Civil Engineering Program, Department of Mechanical Engineering, State University of New York at Stony Brook, New York 11794 (United States); Bae, Sungchul [Department of Civil and Environmental Engineering, University of California, Berkeley, CA 94720 (United States); Duan, Xiaonan [Department of Materials Science and Engineering, Cornell University, Ithaca, NY 14853 (United States); Giannelis, Emmanuel P. [Department of Materials Science and Engineering, Cornell University, Ithaca, NY 14853 (United States); Center for Refining and Petrochemicals, The Research Institute, King Fahd University of Petroleum and Minerals, Dhahran 31261 (Saudi Arabia); Monteiro, Paulo M. [Department of Civil and Environmental Engineering, University of California, Berkeley, CA 94720 (United States)

    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{sup −1} and 257 mg g{sup −1}, respectively) of the CLDHs were comparable to the theoretical capacity of Friedel's salt (2 mol mol{sup −1} or 121 mg g{sup −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. - Highlights: • We examine the adsorption equilibrium and kinetics of CLDH in the hydrated cement. • CLDH capacity to bind chloride ions in the hydrated cement paste is determined. • We model chloride adsorption by CLDH through the cement matrix. • CLDH reforms the layered structure with ion adsorption in the cement matrix.

  13. Calcination products of gibbsite studied by X-ray diffraction, XPS and solid-state NMR

    Energy Technology Data Exchange (ETDEWEB)

    Malki, A. [Laboratoire des structures, propriétés et interactions inter atomiques (LASPI2A), Faculté des sciences et technologies, Université Abbes Laghrour, Khenchela 40000 (Algeria); Mekhalif, Z.; Detriche, S.; Fonder, G. [Laboratoire de Chimie et Electrochimie des Surfaces, Facultés Universitaires Notre-Dame de la Paix, Rue de Bruxelles 61, B-5000 Namur (Belgium); Boumaza, A., E-mail: charif_boumaza@yahoo.com [Laboratoire des structures, propriétés et interactions inter atomiques (LASPI2A), Faculté des sciences et technologies, Université Abbes Laghrour, Khenchela 40000 (Algeria); Djelloul, A. [Laboratoire des structures, propriétés et interactions inter atomiques (LASPI2A), Faculté des sciences et technologies, Université Abbes Laghrour, Khenchela 40000 (Algeria)

    2014-07-01

    The changes caused by heat treatment of gibbsite powder at 300–1473 K were studied using the X-ray diffraction (XRD), X-ray photoemission (XPS) spectra and {sup 27}Al magic angle spinning nuclear magnetic resonance spectroscopy ({sup 27}Al MAS NMR). XRD analysis indicates that the transformation sequence involves the formation of κ-Al{sub 2}O{sub 3} as an intermediate phase between χ- and α-Al{sub 2}O{sub 3}. The crystallite size of χ-Al{sub 2}O{sub 3} is as small as 10 nm. XPS analysis indicates that the ratio of aluminium atoms to oxygen atoms in χ-Al{sub 2}O{sub 3} and κ-Al{sub 2}O{sub 3} increases, whereas the expected ratio is observed in α-Al{sub 2}O{sub 3}. The percentage of AlO{sub 4} units in the transition aluminas follows the same behaviour as the ratio of Al/O. - Graphical abstract: The percentage of AlO{sub 4} units in transition aluminas follows the same behaviour as the ratio of Al/O. - Highlights: • Calcination products of gibbsite studied by XRD, XPS and solid-state NMR. • The crystallite size of χ-Al{sub 2}O{sub 3} is as small as 10 nm. • The Al/O atomic ratio determined by XPS is larger than 2/3 in χ-Al{sub 2}O{sub 3} and κ-Al{sub 2}O{sub 3}. • The percentage of AlO{sub 4} in the aluminas follows the same behaviour as the Al/O atomic ratio.

  14. Synthesis and characterization of nanocrystalline hydroxyapatite gel and its application as scaffold aggregation

    Directory of Open Access Journals (Sweden)

    Leonardo Ribeiro Rodrigues

    2012-12-01

    Full Text Available The sol-gel process is a technique used to synthesize materials from colloidal suspensions and, therefore, is suitable for preparing materials in the nanoscale. In this work hydroxyapatite was used due to its known properties in tissue engineering. Hydroxyapatite Ca10(PO46(OH2 is a bioactive ceramic which is found in the mineral phase of bone tissue and is known for its great potential in tissue engineering applications. For this reason, this material can be applied as particle aggregates on ceramic slurry, coating or film on materials with a poorer biological response than hydroxyapatite. In this work, hydroxyapatite gel was obtained by the sol-gel process and applied as nanoparticle aggregation in the mixture of hydroxyapatite and tricalcium phosphate to form a ceramic slurry. This process is the polymer foam replication technique used to produce scaffolds, which are used in tissue engineering. For HA gel characterization it was used enviromental scanning electron microscopy (ESEM, transmission electron microscopy (TEM, electron energy loss spectroscopy (EELS, scanning electron microscopy (SEM, X-ray diffraction (XRD and X-ray fluorescence (XRF. The crystallite size was calculated from XRD data using the Scherrer equation. The nanoparticles size before firing was approximately 5nm. The crystallite size calculated after calcination was approximately 63 nm. The EELS results showed that calcium phosphate was obtained before firing. After HA gel calcination at 500 ºC the XRD results showed hydroxyapatite with a small content of beta-TCP. The scaffolds obtained by polymer foam replication technique showed a morphology with adequate porosity for tissue engineering.

  15. Extended Development Work to Validate a HLW Calcine Waste Form via INL's Cold Crucible Induction Melter

    Energy Technology Data Exchange (ETDEWEB)

    James A. King; Vince Maio

    2011-09-01

    To accomplish calcine treatment objectives, the Idaho Clean-up Project contractor, CWI, has chosen to immobilize the calcine in a glass-ceramic via the use of a Hot-Isostatic-Press (HIP); a treatment selection formally documented in a 2010 Record of Decision (ROD). Even though the HIP process may prove suitable for the calcine as specified in the ROD and validated in a number of past value engineering sessions, DOE is evaluating back-up treatment methods for the calcine as a result of the technical, schedule, and cost risk associated with the HIPing process. Consequently DOE HQ has requested DOE ID to make INL's bench-scale cold-crucible induction melter (CCIM) available for investigating its viability as a process alternate to calcine treatment. The waste form is the key component of immobilization of radioactive waste. Providing a solid, stable, and durable material that can be easily be stored is the rationale for immobilization of radioactive waste material in glass, ceramic, or glass-ceramics. Ceramic waste forms offer an alternative to traditional borosilicate glass waste forms. Ceramics can usually accommodate higher waste loadings than borosilicate glass, leading to smaller intermediate and long-term storage facilities. Many ceramic phases are known to possess superior chemical durability as compared to borosilicate glass. However, ceramics are generally multiphase systems containing many minor phase that make characterization and prediction of performance within a repository challenging. Additionally, the technologies employed in ceramic manufacture are typically more complex and expensive. Thus, many have proposed using glass-ceramics as compromise between in the more inexpensive, easier to characterize glass waste forms and the more durable ceramic waste forms. Glass-ceramics have several advantages over traditional borosilicate glasses as a waste form. Borosilicate glasses can inadvertently devitrify, leading to a less durable product that could

  16. 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...

  17. The Influence of Calcined Clay Pozzolan, Low-Cao Steel Slag and Granite Dust On the Alkali-Silica Reaction in Concrete

    Directory of Open Access Journals (Sweden)

    James Sarfo-Ansah

    2015-08-01

    Full Text Available The influence of low CaO steel slag, calcined clay and granite dust on the alkali-silica reaction was investigated over a period of 35 days under accelerated curing conditions. The mineral admixtures were used to replace varying portions of high alkali Portland limestone cement up to an admixture content of 25% in order to study their effect on the alkali-silica reaction (ASR. Portland limestone cement used for the study had a total Na2Oeq of 4.32. XRD analysis of hydrated mortar bar samples confirmed the formation of an expansive sodium silica gel in the reference Portland cement mortar bar as the agent responsible for ASR. Stable calcium silicates were formed in the mortar bars containing calcined clay in increasing quantities whilst the presence of the sodium silicate gel decreased.The occurrence of these stable silicates in hydrated samples containing steel slag and granite dust was however minimal, compared to calcined clay cement mortars. The highest expansion was recorded for granite dust mortar bars, reaching a maximum of 25.98% at 35 days. Mortar-bar expansion decreased as calcined clay content in the cement increased;mortar bars with 25% calcined clay were the least expansive recording expansion less than 0.1% at all test ages. Whilst the expansion was reduced by between 42.5% and 107.8% at 14 days with increasing calcined clay content, expansion rather increased between 36.8% and 169.5% at 14 days with increasing granite dust content.Steel slag mortar bars experienced reduction in 14 days expansion between 14.3% - 46.2%.The study confirms that steel slag and calcined clay pozzolan have greater influence on ASR in mortar bars than granite dust and shows that calcined clay and low CaO steel slag could be considered as remedial admixtures for ASR at replacement levels of 25% and 15% respectively.

  18. 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.

  19. Limestone calcination under calcium-looping conditions for CO2 capture and thermochemical energy storage in the presence of H2O: an in situ XRD analysis.

    Science.gov (United States)

    Valverde, Jose Manuel; Medina, Santiago

    2017-03-02

    This work reports an in situ XRD analysis of whether the calcination/carbonation behavior of natural limestone (CaCO3) is affected by the addition of H2O to the calciner at a very low concentration under relevant Calcium-Looping (CaL) conditions for CO2 capture in coal fired power plants (CFPP) and Thermochemical Energy Storage (TCES) in Concentrated Solar Power plants (CSP). Previous studies have demonstrated that the presence of steam in the calciner at a high concentration yields a significant increase in the reaction rate. However, a further undesired consequence is the serious deterioration of the CaO mechanical strength, which would lead to particle attrition and mass loss in any CaL process based on the use of circulating fluidized beds. The results presented in this manuscript on the time evolution of the wt% and crystallite size of the phases involved in the calcination/carbonation reactions indicate that the calcination rate is still notably increased by the presence of H2O at very low concentrations whereas the reactivity toward carbonation and crystal structure of the formed CaO are not essentially affected, which suggests that the CaO mechanical strength is not impaired. Thus, the benefit of using steam for calcination in the CaL process could be still retained while at the same time particle attrition would not be promoted.

  20. AGGREGATE RATING MODEL IN THE TOURISM INDUSTRY

    Directory of Open Access Journals (Sweden)

    Maris Angela

    2014-07-01

    Full Text Available In the paper the authors present a model aggregate rating based on credit-scoring models, banking models and their rating model. Multi-criteria approach and an aggregate model better capture business risk of the company.

  1. Acetone:isomedzation and aggregation

    Institute of Scientific and Technical Information of China (English)

    HU Zhan; JIN Ming-xing; XU Xue-song; CHENG Xi-hui; DING Da-jun

    2006-01-01

    The advanced experimental and theoretical techniques enable us to obtain information on the rearrangement of atoms or molecules in a reaction nowadays.As an example,we report on our research work on acetone isomerization and aggregation to give an insight into the reaction pathways,the products and their structures,and the growth regularity of aggregation.The evidences on the structural change of acetone and the stability of acetone clusters are found by a laser ionization mass spectrometer and the results are interpreted from theoretical analysis based on the DFT/B3LYP method.Various isomerization channels of acetone have been established and the optimal structures of the neutral clusters (CH3COCH3)n and the protonated acetone clusters (CH3COCHa)n H+ for n=1-7 have been determined.

  2. 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.

  3. SMALL-SCALE TESTING OF PLUTONIUM (IV) OXALATE PRECIPITATION AND CALCINATION TO PLUTONIUM OXIDE TO SUPPORT THE MOX FEED MISSION

    Energy Technology Data Exchange (ETDEWEB)

    Crowder, M.; Pierce, R.; Scogin, J.; Daniel, G.; King, W.

    2012-06-25

    The H-Canyon facility will be used to dissolve Pu metal for subsequent purification and conversion to plutonium dioxide (PuO{sub 2}) using Phase II of HB-Line. To support the new mission, SRNL conducted a series of experiments to produce calcined plutonium (Pu) oxide and measure the physical properties and water adsorption of that material. This data will help define the process operating conditions and material handling steps for HB-Line. An anion exchange column experiment produced 1.4 L of a purified 52.6 g/L Pu solution. Over the next nine weeks, seven Pu(IV) oxalate precipitations were performed using the same stock Pu solution, with precipitator feed acidities ranging from 0.77 M to 3.0 M nitric acid and digestion times ranging from 5 to 30 minutes. Analysis of precipitator filtrate solutions showed Pu losses below 1% for all precipitations. The four larger precipitation batches matched the target oxalic acid addition time of 44 minutes within 4 minutes. The three smaller precipitation batches focused on evaluation of digestion time and the oxalic acid addition step ranged from 25-34 minutes because of pump limitations in the low flow range. Following the precipitations, 22 calcinations were performed in the range of 610-690 C, with the largest number of samples calcined at either 650 or 635 C. Characterization of the resulting PuO{sub 2} batches showed specific surface areas in the range of 5-14 m{sup 2}/g, with 16 of the 22 samples in the range of 5-10 m2/g. For samples analyzed with typical handling (exposed to ambient air for 15-45 minutes with relative humidities of 20-55%), the moisture content as measured by Mass Spectrometry ranged from 0.15 to 0.45 wt % and the total mass loss at 1000 C, as measured by TGA, ranged from 0.21 to 0.58 wt %. For the samples calcined between 635 and 650 C, the moisture content without extended exposure ranged from 0.20 to 0.38 wt %, and the TGA mass loss ranged from 0.26 to 0.46 wt %. Of these latter samples, the samples

  4. Familial aggregation of cluster headache

    Directory of Open Access Journals (Sweden)

    Simao Cruz

    2013-11-01

    Full Text Available Several studies suggest a strong familial aggregation for cluster headache (CH, but so far none of them have included subjects with probable cluster headache (PCH in accordance with the International Classification of Headache Disorders. Objective To identify cases of probable cluster headache and to assess the familial aggregation of cluster headache by including these subjects. Method Thirty-six patients attending a headache consultation and diagnosed with trigeminal autonomic headaches were subjected to a questionnaire-based interview. A telephone interview was also applied to all the relatives who were pointed out as possibly affected as well as to some of the remaining relatives. Results Twenty-four probands fulfilled the criteria for CH or PCH; they had 142 first-degree relatives, of whom five were found to have CH or PCH, including one case of CH sine headache. The risk for first-degree relatives was observed to be increased by 35- to 46-fold. Conclusion Our results suggest a familial aggregation of cluster headache in the Portuguese population.

  5. 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.

  6. Elimination of phosphate and zirconium in the high-activity fraction resulting from TRUEX partitioning of ICPP zirconium calcines

    Energy Technology Data Exchange (ETDEWEB)

    Brewer, K.N.; Tillotson, R.D.; Tullock, P.A. [and others

    1997-07-01

    Laboratory testing was undertaken with the aim of developing a TRUEX flowsheet that would efficiently remove actinides from solutions of dissolved zirconium calcine and minimize the glass volume produced from the ensuing high-activity fraction. A TRUEX flowsheet is recommended for testing in the 2-cm centrifugal contactor pilot-plant based on the results from this testing. These laboratory tests show that zirconium recovery in the high activity fraction is minimized by scrubbing with an optimized NHF concentration of 0.2 M. This NH4F concentration in the scrub allowed the HEDPA strip concentration to be reduced from 0.04 M to 0.004 M because HEDPA is not consumed by zirconium. Complete TRU stripping was also achieved in these laboratory tests with 0.004 M HEDPA. Data from the small-scale laboratory batch contact tests were used in the Generic TRUEX Model (GTM) to evaluate the proposed flowsheet under counter-current conditions. GTM results indicate the raffinate will meet the Class A non-TRU limit of < 10 nCi/g in six extraction stages (O/A = 1), and quantitative actinide recovery will be achieved with the 0.004 M HEDPA in six strip stages (O/A = 1). Only 6.6 % of the initial zirconium concentration is anticipated to be recovered with the actinides, indicating the four scrub stages (O/A = 3) efficiently removes zirconium from the TRUEX solvent. In addition to recommending an improved TRUEX flowsheet for testing in the 2-cm centrifugal contactor pilot-plant, this work has shown that small reductions in zirconium extraction drastically improves flowsheet performance. These small changes in zirconium extraction can be accomplished by modifying the calcine dissolution parameters. Therefore, further calcine dissolution testing followed by TRUEX testing with the resulting feed solutions is also recommended.

  7. An exact approach for aggregated formulations

    DEFF Research Database (Denmark)

    Gamst, Mette; Spoorendonk, Simon

    cause an infeasible solution. In this paper, we consider (mixed) integer program formulations and propose a method for ensuring an optimal solution to the original (disaggregated) problem using an aggregated formulation. The method is based on Benders’ decomposition on a combination of the disaggregated...... mathematical formulation and the aggregated formulation. The method allows usage of relaxed aggregated formulations and enables branching on both aggregated and disaggregated variables. Also, the method guarantees an LP bound at least as good as those for the disaggregated and aggregated formulations...

  8. [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.

  9. [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.

  10. Microwave Sintering of W-15Cu Ultrafine Composite Powder Prepared by Spray Drying & Calcining-continuous Reduction Technology

    Institute of Scientific and Technical Information of China (English)

    SHU Jingping; SHI Xiaoliang; WANG Shuwei; YANG Xingyong; ZHANG Qiaoxin; WANG Yufu

    2011-01-01

    The effects of microwave sintering and conventional H2 sintering on the microstructure and properties of W-l5Cu alloy using ultrafine W-15Cu composite powder fabricated by spray drying & calcining-continuous reduction technology were investigated. In comparison to the conventional H2 sintering processing, microwave sintefing to W-15Cu can be achieved at lower sintefing temperature and shorter sintering time. Furthermore, higher performances in microwave sintered compacts were obtained, but high microwave sintering temperature or long microwave sintering time could result in coarser microstructures.

  11. Electrochemical characterization for lithium vanadium phosphate with different calcination temperatures prepared by the sol–gel method

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Yongchao [Faculty of Materials Science and Chemistry, China University of Geosciences, Wuhan 430074 (China); Wang, Shengping, E-mail: spwang@cug.edu.cn [Faculty of Materials Science and Chemistry, China University of Geosciences, Wuhan 430074 (China); Tao, Du; Dai, Yu [Faculty of Materials Science and Chemistry, China University of Geosciences, Wuhan 430074 (China); Yu, Jingxian [ARC Centre of Excellence for Nanoscale BioPhotonics (CNBP), School of Chemistry and Physics, The University of Adelaide, Adelaide, SA 5005 (Australia)

    2015-09-15

    Li{sub 3}V{sub 2}(PO{sub 4}){sub 3}/C (LVP/C) composite materials were synthesized via a sol–gel method with oxalic acid as the chelating agent and polyethylene glycol (PEG) as the supplementary carbon source. The oxalic acid and PEG serve as double carbon sources. This study focused on the effect of different calcination temperatures on the electrochemical properties of Li{sub 3}V{sub 2}(PO{sub 4}){sub 3}. The diffraction peaks for all of the samples are well indexed to monoclinic Li{sub 3}V{sub 2}(PO{sub 4}){sub 3} with a P2{sub 1}/n space group. The TGA data indicate that the residual carbon content of LVP/C-700 is the highest (i.e., 2.31 wt.%), and as the calcination temperature increased, the residual carbon content of the material gradually decreased. SEM and TEM analyses indicated that the LVP particles that were calcined at 700 °C exhibit a uniform particle size distribution and the carbon coating exhibited a complete and orderly moderate thickness. The LVP/C-700 material exhibits the best electrochemical performance in the voltage range of 3.0 to 4.3 V and 0.1 C where the initial discharge capacity can reach 128.98 mAh g{sup −} {sup 1}. Even after 200 cycles, the discharge capacity was 119.31 mAh g{sup −} {sup 1}, and the capacity retention rate was 92.49%. - Highlights: • Li{sub 3}V{sub 2}(PO{sub 4}){sub 3}/C composite materials have been synthesized via a sol–gel method with double carbon sources. • The different calcination temperatures affect the grain growth and crystallinity of the Li{sub 3}V{sub 2}(PO{sub 4}){sub 3}/C materials. • The LVP/C-700 material exhibites the largest lithium ion diffusivity and electronic conductivity.

  12. Effect of Calcination Temperature on Structural Properties and Photocatalytic Activity of Ceria Nanoparticles Synthesized Employing Chitosan as Template

    Directory of Open Access Journals (Sweden)

    Angela B. Sifontes

    2013-01-01

    Full Text Available Ceria nanoparticles were synthesized employing chitosan as template and thermal treatment at different temperatures (350, 650, and 960°C. The effect of calcination temperature on structural properties and photocatalytic activity of ceria nanopowder was also tested. Degradation of an azo dye, Congo Red (CR as a model aqueous pollutant, was investigated by means of photocatalysis of ceria nanoparticles under visible light irradiation. The influence of catalyst amount, initial CR concentrations, and degradation reaction kinetics were studied. The results were compared with commercial CeO2 at the same degradation conditions.

  13. Aggregation of Diesel Contaminated Soil for Bioremediation

    Institute of Scientific and Technical Information of China (English)

    Yu Ying; Shi Xiu-hong; Li Song; Xu Jing-gang

    2014-01-01

    Diesel contaminated soil (DCS) contained a large amount of the hydrocarbons and salt which was dominated by soluble sodium chloride. Aggregation process which made the desired aggregate size distribution could speed up the degradation rate of the hydrocarbons since the aggregated DCS had better physical characteristics than the non-aggregated material. Artificial aggregation increased pores >30 µm by approximately 5% and reduced pores <1 µm by 5%, but did not change the percentage of the pores between 1 and 30 µm. The saturated hydraulic conductivity of non-aggregated DCS was 5×10-6 m• s-l, but it increased to 1×10-5 m• s-l after aggregation. The compression index of the non-aggregated DCS was 0.0186; however, the artificial aggregates with and without lime were 0.031 and 0.028, respectively. DCS could be piled 0.2 m deep without artificial aggregation; however, it could be applied 0.28 m deep when artificial aggregates were formed without limiting O2 transport.

  14. Bouncing Behavior of Microscopic Dust Aggregates

    CERN Document Server

    Seizinger, Alexander

    2013-01-01

    Context: Bouncing collisions of dust aggregates within the protoplanetary may have a significant impact on the growth process of planetesimals. Yet, the conditions that result in bouncing are not very well understood. Existing simulations studying the bouncing behavior used aggregates with an artificial, very regular internal structure. Aims: Here, we study the bouncing behavior of sub-mm dust aggregates that are constructed applying different sample preparation methods. We analyze how the internal structure of the aggregate alters the collisional outcome and determine the influence of aggregate size, porosity, collision velocity, and impact parameter. Methods: We use molecular dynamics simulations where the individual aggregates are treated as spheres that are made up of several hundred thousand individual monomers. The simulations are run on GPUs. Results: Statistical bulk properties and thus bouncing behavior of sub-mm dust aggregates depend heavily on the preparation method. In particular, there is no uni...

  15. PERCOLATION OF RANDOM CYLINDER AGGREGATES

    Directory of Open Access Journals (Sweden)

    Dominique Jeulin

    2011-05-01

    Full Text Available The percolation threshold ρc of Boolean models of cylinders with their axis parallel to a given direction is studied by means of simulations. An efficient method of construction of percolating connected components was developed, and is applied to one or two scales Boolean model, in order to simulate the presence of aggregates. The invariance of the percolation threshold with respect to affine transformations in the common direction of the axis of cylinders is approximately satisfied on simulations. The prediction of the model (ρc close to 0.16 is consistent with experimental measurements on plasma spray coatings, which motivated this study.

  16. Effect of Calcinated Oyster Shell Powder on Growth, Yield, Spawn Run, and Primordial Formation of King Oyster Mushroom (Pleurotus Eryngii

    Directory of Open Access Journals (Sweden)

    Young-Chan Kim

    2011-03-01

    Full Text Available This study was conducted to evaluate the calcium (Ca absorption efficacy of king oyster mushroom (Pleurotus eryngii grown on sawdust medium supplemented with Ca-sources, including oyster shell powder, and to determine the efficacy of oyster shell powder as a calcium supplement on growth, yield, spawn run and primordial formation of P. eryngii. Optimum calcination of oyster shell powder was achieved at the temperature of 620.56 °C. A 1% supplementation of oyster shell powder in sawdust medium did not suppress the mycelial growth of P. eryngii. Also the supplementation of 2% calcinated oyster shell powder to sawdust medium potentially increased the calcium content up to a level of 315.7 ± 15.7 mg/100 g in the fruiting body of P. eryngii, without extension of duration of spawn run and the retardation of the days to primordial formation. These results suggest that the shellfish by-products, including oyster shell powder, can be utilized to develop calcium enriched king oyster mushrooms.

  17. Photocatalytic Activity and Photocurrent Properties of TiO2 Nanotube Arrays Influenced by Calcination Temperature and Tube Length

    Science.gov (United States)

    Hou, Jian; Zhang, Min; Yan, Guotian; Yang, Jianjun

    2012-06-01

    In this article, titanium oxide nanotube arrays (TiO2-NTAs) were fabricated by anodic oxidation in an ethylene glycol (EG) electrolyte solution containing 0.25 wt.% NH4F. By varying anodized time and annealed temperature, the obtained nanotube arrays behaved different photocatalytic (PC) activities and photocurrent properties. These samples were characterized by scanning electronic microscope (SEM), X-ray powder diffraction (XRD). It was indicated in SEM images that TiO2 nanotube manifests highly ordered structure which, however, has been completely destroyed when the temperature comes to 800°C. XRD manifested that TiO2 nanotubes with various kinds of length all possessed anatase crystallite when annealed at 500°C; meanwhile, with certain length, TiO2-NTAs annealed at series calcination temperature range of 300-600°C also presented anatase crystallite, which is gradually enhanced with the increment of temperature. At 700°C, mixed structure was observed which was made up of proportions of overwhelming anatase and toothful rutile. Methyl blue (MB) degradation and photocurrent measurement testified that TiO2-NTAs under 4 h oxidation and 3 h of 600°C calcination manifested the highest activity and photocurrent density.

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

    Science.gov (United States)

    Venkatesan, Jayachandran; Qian, Zhong Ji; Ryu, BoMi; Thomas, Noel Vinay; Kim, Se Kwon

    2011-06-01

    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 µm, 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.

  19. Continuous production of biodiesel from cottonseed oil and methanol using a column reactor packed with calcined sodium silicate base catalyst☆

    Institute of Scientific and Technical Information of China (English)

    Xia Gui; Sichen Chen; Zhi Yun

    2016-01-01

    Sodium silicate and that calcined at 400 °C for 2 h were used to catalyze the transesterification of cottonseed oil with methanol. Calcined sodium silicate (CSS) catalyst exhibited much higher catalytic activity and stability. A maximum biodiesel yield of 98.9%was achieved at methanol/oil mole ratio of 12:1, reaction temperature 65 °C, reaction time 3.0 h, and CSS/oil mass ratio of 2 wt%. After 7 consecutive reactions without any treatment, biodiesel yield reduced to 82.5%. Considering technological and economic feasibility, CSS base catalyst supported onθrings was prepared for continuous transesterification. The maximum yield was 99.1%under optimum conditions (reaction temperature 55 °C, methanol velocity 1 ml·min−1, oil velocity 3 ml·min−1, and 5 tower sec-tions). These results indicate that this new continuous biodiesel production process and apparatus present a great potential for industrial application in biodiesel.

  20. Sorption Removal of Pb(Ⅱ) from Solution by Uncalcined and Calcined MgAl-Layered Double Hydroxides

    Institute of Scientific and Technical Information of China (English)

    ZHANG, Shu-Qin; HOU, Wan-Guo

    2007-01-01

    Layered double hydroxide (LDH) with a Mg/Al molar ratio of 1∶1 was synthesized by using a co-precipitation method and its calcined product (CLDH) was obtained by calcination of the MgAl-LDH at 500 ℃. The sorption removal of Pb2+ from solution was investigated, finding that both LDH and CLDH show good sorption ability and they could be used as a new type of environmental sorbent for the removal of Pb2+ from water. The sorption kinetics and the sorption isotherms of Pb2+ on both LDH and CLDH can be described by the pseudo-second order kinetics and Freundlich isotherm, respectively, under the studied conditions. The sorption amounts of Pb2+ on LDH and CLDH are independent of pH in a pH range of about 3-10. The presence of NaNO3 may inhibit the sorption of Pb2+ on LDH while hardly affect that on CLDH. The sorption mechanism of Pb2+ on LDH and CLDH may be attributed to the surface precipitation and the surface complex adsorption. The surface complex adsorption may be further distinguished to the chemical binding adsorption forming the inner-sphere surface complexes and the electrostatic binding adsorption forming the outer-sphere surface complexes. The sorption mechanism of Pb2+ on LDH may be attributed to the surface precipitation and the electrostatic binding adsorption, while that on CLDH may be attributed to the surface precipitation and the chemical binding adsorption.

  1. Effect of Different Calcination Temperatures on the Structural and Photocatalytic Performance of Bi-TiO2/SBA-15

    Directory of Open Access Journals (Sweden)

    Jing Ma

    2013-01-01

    Full Text Available The new novel material Bi-TiO2/SBA-15 was synthesized by an easy wet impregnation method. A combination of XRD, XPS, Raman, N2 adsorption-desorption isotherm measurement, TEM, and solid state UV-Vis spectroscopy has been used to characterize the Bi-TiO2/SBA-15 material. It was found that SBA-15 retained the ordered hexagonal mesostructure after incorporation of TiO2 and Bi. The photodecomposition of rhodamine B (RhB in aqueous medium was selected to evaluate the photocatalytic performance of Bi-TiO2/SBA-15 under visible light irradiation (λ≥420 nm. The experiment results indicated that Bi-TiO2/SBA-15 exhibited higher photocatalytic activities than pure TiO2 and Bi2O3. The influences of calcination temperature were studied. It strongly influenced the activity of the samples. The sample calcined at 550°C shows the highest photocatalytic activity in the decomposition of RhB under visible light. The catalyst preserved almost its initial photocatalytic activity after six reuses.

  2. Reaction process of monazite and bastnaesite mixed rare earth minerals calcined by CaO-NaCl-CaCl2

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The decomposition reactions of monazite and bastnaesite mixed rare earth minerals calcined by CaO-NaCl-CaCl2 were studied by means of TG-DTA and XRD. The results show that the process of the minerals decomposed by CaO involves two steps.The first step occurs in the temperature range of 425-540 ℃, and the main reactions are bastnaesite decomposition, i.e. REOF reacts with CaO to produce RE2O3 and CaF2, and Ce2O3 is oxidized to CeO2. During this step, CaCO3 is formed at about 500 ℃. The second step takes place in the temperature range of 610-700 ℃, and the reactions are monazite decomposition into RE2O3,Ca5F(PO4)3 and Ca3(PO4)2 by CaO and CaF2. In this process, the decomposition ability is improved because CaO from CaCO3decomposing has high chemical activity. In calcining process, the new formed Ca5F(PO4)3 restrains fluorine that can escape in form of gaseous compound. The decomposition ratio of the mixed rare earth minerals reaches 90.8% at 700 ℃.

  3. Effect of Grain and Calcinations Kaolin Additives on Some Mechanical and Physical properties on Low DensityPolyethylene Composites

    Directory of Open Access Journals (Sweden)

    Zanaib Y. Shnean

    2008-01-01

    Full Text Available In this work, a composite material was prepared from Low-density polyethylene (LDPE with different weight percent of grain and calcinations kaolin at temperature of (850oC using single screw extruder and a mixing machine operated at a temperature between (190-200oC. Some of mechanical and physical properties such as tensile strength, tensile strength at break, Young modulus, and elongation at break, shore hardness and water absorption were determined at different weight fraction of filler (0, 2, 7, 10 and 15%. It was found that the addition of filler increases the modulus of elasticity, elongation at break, shore hardness and impact strength; on other hand, it decreases the tensile strength and tensile strength at a break. Absorption test was carried out in water at different immersion times and different composite .The results of absorption show that it obeys Fick’s law and after the addition of kaolin the amount of absorption decrease. Calcinations kaolin filler produces better mechanical properties , than grain kaolin fillers.

  4. 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.

  5. 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.

  6. 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.

  7. Effect of calcinated oyster shell powder on growth, yield, spawn run, and primordial formation of king oyster mushroom (Pleurotus eryngii).

    Science.gov (United States)

    Choi, Ung-Kyu; Lee, Ok-Hwan; Kim, Young-Chan

    2011-03-10

    This study was conducted to evaluate the calcium (Ca) absorption efficacy of king oyster mushroom (Pleurotus eryngii) grown on sawdust medium supplemented with Ca-sources, including oyster shell powder, and to determine the efficacy of oyster shell powder as a calcium supplement on growth, yield, spawn run and primordial formation of P. eryngii. Optimum calcination of oyster shell powder was achieved at the temperature of 620.56 °C. A 1% supplementation of oyster shell powder in sawdust medium did not suppress the mycelial growth of P. eryngii. Also the supplementation of 2% calcinated oyster shell powder to sawdust medium potentially increased the calcium content up to a level of 315.7 ± 15.7 mg/100 g in the fruiting body of P. eryngii, without extension of duration of spawn run and the retardation of the days to primordial formation. These results suggest that the shellfish by-products, including oyster shell powder, can be utilized to develop calcium enriched king oyster mushrooms.

  8. 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).

  9. 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 MoO(3), Bi(2)O(3) and V(2)O(5), while the use of WO(3,) Nb(2)O(5) 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 MoO(3) > Bi(2)O(3) > V(2)O(5), which agreed well with the acidity of the metal oxides. The importance of the acidic properties of metal oxides for ammonia sensing was clarified.

  10. An interdisciplinary physical-chemical approach for characterization of arsenic in a calciner residue dump in Cornwall (UK).

    Science.gov (United States)

    van Elteren, Johannes Teun; Slejkovec, Zdenka; Arcon, Iztok; Glass, Hylke-Jan

    2006-02-01

    During the later stages of hard-rock mining in Cornwall, UK, widespread processing and refining of arsenic in purpose-built calciners resulted in severe, localized contamination of soils with arsenic. Several physical-chemical techniques were applied to characterize arsenic in a calciner residue dump: X-ray powder diffraction (XRD), sequential extraction combined with hyphenated speciation methods, and X-ray absorption spectroscopic (XAS) methods such as XANES (X-ray absorption near-edge structure) and EXAFS (extended X-ray absorption fine structure). Arsenic was predominantly present in pentavalent form, bound to amorphous or poorly-crystalline hydrous oxides of Fe (probably alpha-hematite). A small amount of a non-classified crystalline iron arsenate phase was found, viz. Fe2(As(AsO4)3). There was also evidence for the presence of some arsenate bound to quartz (alpha-SiO2). The overall results make us believe that the normally assumed relative safety, from a mobility point of view, is questionable since only a small fraction of arsenic is found in a crystalline iron arsenate form.

  11. Aggregation kinetics of a simulated telechelic polymer

    Science.gov (United States)

    Wilson, Mark; Rabinovitch, Avinoam; Baljon, Arlette R. C.

    2011-12-01

    We investigate the aggregation kinetics of a simulated telechelic polymer gel. In the hybrid molecular dynamics (MD)/Monte Carlo (MC) algorithm, aggregates of associating end groups form and break according to MC rules, while the position of the polymers in space is dictated by MD. As a result, the aggregate sizes change over time. In order to describe this aggregation process, we employ master equations. They define changes in the number of aggregates of a certain size in terms of reaction rates. These reaction rates indicate the likelihood that two aggregates combine to form a large one, or that a large aggregate splits into two smaller parts. The reaction rates are obtained from the simulations for a range of temperatures. Our results indicate that the rates are not only temperature dependent, but also a function of the sizes of the aggregates involved in the reaction. Using the measured rates, solutions to the master equations are shown to be stable and in agreement with the aggregate size distribution, as obtained directly from simulation data. Furthermore, we show how temperature-induced variations in these rates give rise to the observed changes in the aggregate distribution that characterizes the sol-gel transition.

  12. Pyridine Aggregation in Helium Nanodroplets

    Science.gov (United States)

    Nieto, Pablo; Poerschke, Torsten; Habig, Daniel; Schwaab, Gerhard; Havenith, Martina

    2012-06-01

    Pyridine crystals show the unusual property of isotopic polymorphism. Experimentally it has been observed that deuterated pyridine crystals exist in two phases while non-deuterated pyridine does not show a phase transition. Therefore, although isotopic substitution is the smallest possible modification of a molecule it greatly affects the stability of pyridine crystals. A possible experimental approach in order to understand this striking effect might be the study of pyridine aggregation for small clusters. By embedding the clusters in helium nanodroplets the aggregates can be stabilized and studied by means of Infrared Depletion Spectroscopy. Pyridine oligomers were investigated in the C-H asymmetric vibration region (2980-3100 cm-1) using this experimental technique. The number of molecules for the clusters responsibles for each band were determined by means of pick-up curves as well as mass sensitive depletion spectra. Furthermore, the intensity dependence of the different bands on applying a dc electric field was studied. The assignment of the different structures for pyridine clusters on the basis of these measurements were also carried out. S. Crawford et al., Angew. Chem. Int. Ed., 48, 755 (2009).

  13. Estimating Aggregate Demand in Egypt

    Directory of Open Access Journals (Sweden)

    Noha EMARA

    2016-03-01

    Full Text Available Abstract. This econometric study seeks to determine the most important factors of aggregate demand in Egypt so as to provide insight into how this developing nation can grow economically in the coming years. The Ordinary Least Squares estimation method was used in order to estimate nominal GDP for the time period 1975 to 2009. Based on the results the real interest rate, the inflation rate, the growth rate of government expenditure, and the growth rate of the money supply are the most statistically and economically significant factors of the growth rate of nominal GDP for the coming year. A one percent change in the growth rate of the previous year government expenditure is predicted to cause the growth rate of the current year nominal GDP to increase by 54%.The role of government expenditures on public sector wage expansion is discussed in this study as to shed light on this factor’s significant influence on income inequality post-1975 in Egypt, which will continue to impact nominal GDP and social conditions for the developing nation in the coming years.Keywords. GDP, Aggregate Demand, Egypt.JEL. E25, O40, Q11.

  14. Effect of calcination temperatures on the electrochemical performances of nickel oxide/reduction graphene oxide (NiO/RGO) composites synthesized by hydrothermal method

    Science.gov (United States)

    Chen, Gang; Guan, Hongtao; Dong, Chengjun; Xiao, Xuechun; Wang, Yude

    2016-11-01

    A series of NiO/RGO composites based on NiO nanoparticles anchored on layered RGO surfaces were proposed by the same hydrothermal method combined with different calcination temperatures (250, 300, 400 and 500 °C). The effects of calcination temperatures on the capacitive behaviors have been discussed by investigating the components, morphologies, surface conditions of the NiO/RGO composites. The specific capacitance values of NiO/RGO composites calcined at 250, 300, 400 and 500 °C are 950, 553, 375 and 205 F/g at the current density of 1 A/g and the corresponding capacitance retention are 91.3%, 83.9%, 71.9% and 67.3% after 1000 cycles at the current density of 10 A/g. The results suggest the calcination temperature plays an important role in the electrochemical performances of NiO/RGO composites and the electrochemical performances were deteriorated with the increasing calcination temperatures.

  15. Effect of calcination temperature on physical parameters and photocatalytic activity of mesoporous titania spheres using chitosan/poly(vinyl alcohol) hydrogel beads as a template

    Energy Technology Data Exchange (ETDEWEB)

    Jiang, R. [Department of Environmental Engineering, Taizhou University, Taizhou 318000 (China); Zhejiang Provincial Key Laboratory of Plant Evolutionary Ecology and Conservation, College of Life Science, Taizhou University, Taizhou 318000 (China); State Laboratory of Silica Materials and Department of Chemistry, Zhejiang University, Hangzhou 310027 (China); Zhu, H.-Y., E-mail: zhuhuayue@126.com [Department of Environmental Engineering, Taizhou University, Taizhou 318000 (China); Zhejiang Provincial Key Laboratory of Plant Evolutionary Ecology and Conservation, College of Life Science, Taizhou University, Taizhou 318000 (China); Chen, H.-H. [State Laboratory of Silica Materials and Department of Chemistry, Zhejiang University, Hangzhou 310027 (China); Yao, J. [Department of Environmental Engineering, Taizhou University, Taizhou 318000 (China); Zhejiang Provincial Key Laboratory of Plant Evolutionary Ecology and Conservation, College of Life Science, Taizhou University, Taizhou 318000 (China); Fu, Y.-Q. [Zhejiang Provincial Key Laboratory of Plant Evolutionary Ecology and Conservation, College of Life Science, Taizhou University, Taizhou 318000 (China); Zhang, Z.-Y. [Department of Environmental Engineering, Taizhou University, Taizhou 318000 (China); Xu, Y.-M., E-mail: xuym@css.zju.edu.cn [State Laboratory of Silica Materials and Department of Chemistry, Zhejiang University, Hangzhou 310027 (China)

    2014-11-15

    Highlights: • Mesoporous titania spheres were prepared using CS/PVA hydrogel beads as a template. • The titania spheres prepared was mesoporous structure. • The photocatalytic activity of the mesoporous titania spheres calcined at 500 °C was highest. - Abstract: Mesoporous titania spheres were prepared by modified sol–gel method using chitosan/poly(vinyl alcohol) hydrogel beads as a template. Effects of calcination temperature on physical parameters were investigated by X-ray diffraction (XRD), N{sub 2} adsorption–desorption, Fourier transform infrared (FT-IR) spectra, thermogravimetry and differential thermal analyses (TG-DTA), high-resolution transmission electron microscope (HRTEM) and scanning electron microscopy (SEM). The photocatalytic activity of mesoporous titania spheres prepared was also evaluated by photocatalytic degradation of phenol as a model molecule under UV irradiation. With increasing calcination temperature, average crystallite size and pore size increased. In contrast, Brunauer–Emmett–Teller (BET) specific surface areas, porosity and pore volumes steadily decreased. Results of characterization proved that prepared titania spheres with highly organized pores were mesoporous structure. The photocatalytic activity of mesoporous titania spheres calcined at 500 °C was more effective than those calcined at other temperatures, which were attributed to the porous structure, large BET surface area, crystalline, and smaller crystallite size. This work may provide new insights into the preparation of novel mesoporous titania spheres and further practical applications in the treatment of wastewater.

  16. Effect of calcination temperature on structure and performance of Ni/TiO2-SiO2 catalyst for CO2 reforming of methane

    Institute of Scientific and Technical Information of China (English)

    Sanbing Zhang; Jiankang Wang; Xiaolai Wang

    2008-01-01

    The influence of calcination temperature on the structure and catalytic behavior of Ni/TiO2-SiO2 catalyst, for CO2 reforming of methane to synthesis gas under atmospheric pressure, was investigated. The results showed that the Ni/TiO2-SiO2 catalyst calcined at 700 ℃ had high and stable activity while the catalysts calcined at 550 and 850 ℃ had low and un-stable activity. Depending on the calcination temperature, one, two, or three of the following Ni-contalning species, NiO,Ni2.44Ti0.72Si0.07O4, and NiTiO3 were identified by combining the temperature programmed reduction (TPR) and X-ray diffraction (XRD) results. Their reducibility decreased in the sequence: NiO>Ni2.44Ti0.72Si0.07O4>NiTiO3. It suggests that high and stable activities observed over the Ni/TiO2-SiO2 catalyst calcined at 700 ℃ were induced by the formation of Ni2.44Ti0.72Si0.07O4 and smaller NiO species crystallite size.

  17. 浅谈回转床煅烧炉结构及其特点%Shallow Talk on Rotary Hearth Calciner

    Institute of Scientific and Technical Information of China (English)

    伊英红

    2014-01-01

    It introduces the main components of rotary hearth calciner made by NFC ( Shenyang) Metallurgi-cal Machinery Co . , Ltd . , and briefly describes the use of calsining . And then it detailedly introduces rota-ry hearth calciner system and the development process and characteristics . It compares the rotary hearth calciner with the rotary calcination kiln and briefly analyzes the futural development direction of rotary hearth calciner .%介绍了沈冶金公司承制的回转床煅烧炉的主要组成部分,并对煅烧的用途进行简单描述,对回转床煅烧炉的发展历程及回转床煅烧炉系统及特点进行了较详细的介绍;最后将回转床煅烧炉与煅烧回转窑进行了比较并且对未来发展方向进行简要分析。

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

    Energy Technology Data Exchange (ETDEWEB)

    Zhang Na, E-mail: zhangna06@mails.tsinghua.edu.cn [State Key Lab of New Ceramics and Fine Processing, Department of Materials Science and Engineering, Tsinghua University, Beijing 100084 (China); Liu Xiaoming [School of Metallurgical and Ecological Engineering, University of Science and Technology Beijing, Beijing 100083 (China); Sun Henghu [School of Engineering and Computer Science, University of the Pacific, Stockton, CA 95211 (United States); Li Longtu [State Key Lab of New Ceramics and Fine Processing, Department of Materials Science and Engineering, Tsinghua University, Beijing 100084 (China)

    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, {sup 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.

  19. 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.

  20. Influence of calcination temperature on the structure and morphology of HAp bioceramics; Influencia da temperatura de calcinacao na estrutura e morfologia de bioceramica de HAp

    Energy Technology Data Exchange (ETDEWEB)

    Teixeira, C.M.L.; Santos, P.T.A.; Rodrigues, P.A.; Costa, A.C.F.M. [Universidade Federal de Campina Grande (UFCG), PB (Brazil). Unidade Academica de Engenharia de Materiais

    2012-07-01

    This study aimed to evaluate the influence of calcination temperature on the structure and morphology of samples of hydroxyapatite (HAp) synthesized by the wet method. For hydroxyapatite was used as precursor solutions of calcium hydroxide and phosphoric acid 1M solution of calcium hydroxide was stirred and heated to 80 ° C and then dropwise with a solution of phosphoric acid. After the liquid was evaporated without an oven at 110 ° C and sieved. The sample of PA as synthesized was submitted to calcination at 900 °C and 1100 °C / 2 hours. The samples as synthesized and after calcination were characterized by XRD, XRF, FTIR, SEM. The XRD showed the presence of phase hydroxyapatite for samples without calcining and both calcination temperatures studied. FTIR spectra showed bands group and PO{sub 4}{sup 3-}, CO{sub 3}{sup 2-}. Through the SEM micrograph, there is the formation of agglomerates in the form of porous flakes approximately spherical shape. (author)

  1. Influence of calcination temperature on selective catalytic reduction of NOx with NH3 over CeO2-ZrO2-WO3 catalyst

    Institute of Scientific and Technical Information of China (English)

    李军燕; 宋忠贤; 宁平; 张秋林; 刘昕; 李昊; 黄真真

    2015-01-01

    A series of CeO2-ZrO2-WO3 catalysts for the selective catalytic reduction (SCR) of NO with NH3 were prepared by hydro-thermal method. The influence of calcination temperature on the catalytic activity, microstructure, surface acidity and redox behavior of CeO2-ZrO2-WO3 catalyst was investigated using various characterization methods. It was found that the CeO2-ZrO2-WO3 catalyst calcined at 600 ºC showed the best catalytic performance and excellent N2 selectivity, and yielded more than 90% NO conversion in a wide temperature range of 250–500 ºC with a space velocity (GHSV) of 60000 h–1. As the calcination temperature was increased from 400 to 600 ºC, the NO conversion obviously increased, but decreased at higher calcination temperature. The results implied that the higher surface area, the strongest synergistic interaction, the superior redox property and the highly dispersed or amorphous WO3 species contributed to the excellent SCR activity of the CeO2-ZrO2-WO3 catalyst calcined at 600 ºC.

  2. Effect of calcination temperature on the morphology and electrochemical properties of Co{sub 3}O{sub 4} for lithium-ion battery

    Energy Technology Data Exchange (ETDEWEB)

    Liu Yan [College of Material Science and Engineering, Nanjing University of Aeronautics and Astronautics, Yudao Street 29, Nanjing, Jiangsu 210016 (China); Zhang Xiaogang [College of Material Science and Engineering, Nanjing University of Aeronautics and Astronautics, Yudao Street 29, Nanjing, Jiangsu 210016 (China)], E-mail: azhangxg@163.com

    2009-07-01

    A simple approach to synthesize Co{sub 3}O{sub 4} in mass production by using hexamethylenetetramine (HMT, C{sub 6}H{sub 12}N{sub 4}) as a precipitator via hydrothermal treatment has been developed. The samples were calcinated at different temperatures ranging from 300 to 600 deg. C and characterized by XRD and SEM. The structure became agglomerative and collapsed with an increase in calcination temperature. Evaluation of the electrochemical performance in combination with SEM and BET analysis suggests that there is an optimum calcination temperature for Co{sub 3}O{sub 4}. It is found that the retention capacity of well crystallized Co{sub 3}O{sub 4} hollow microspheres has a higher specific surface area at 300 deg. C and is almost above 94% after the 5th cycle at different current densities of 40 and 60 mA g{sup -1}, which shows good long-life stability and favorable electrochemical behaviors. Using EIS analysis, we demonstrated that lithium-ion conduction inside the SEI layers and charge transfer at the electrode/electrolyte interface became hindered with an increased calcination temperature, which was in good agreement with the electrochemical behaviors of three Co{sub 3}O{sub 4} electrodes. It is proposed that drastic capacity fading and the variation of resistive components (SEI layers and charge transfer) can be influenced by morphologies due to the calcination temperature.

  3. Technology Optimization Research of Calcining Asbestos Tailings with Ammonium Sulfate%石棉尾矿硫酸铵焙烧工艺优化研究

    Institute of Scientific and Technical Information of China (English)

    刘姝抒; 宋贝; 胡志波; 牛保军; 郑水林

    2015-01-01

    Asbestos tailings were preprocessed by ball-milling and calcining. This paper studied the influence of calcination temperature, calcination time and milling time on the roasting effect of asbestos tailings and ammonium sulfate. The result showed that the optimum conditions were that calcination temperature was 500℃, calcination time was 1 h, milling time was 18 min. Through being preprocessed, the leaching ratio of MgO was up from 70.03%to 95.29%.%对石棉尾矿进行预先煅烧和研磨处理,研究了煅烧温度、煅烧时间和研磨时间对石棉尾矿硫酸铵焙烧效果的影响,得到最佳的预处理条件:煅烧温度为500℃,煅烧时间为1 h,研磨时间为18 min。经过预处理后,石棉尾矿硫酸铵焙烧氧化镁溶出率从70.03%提高到95.29%。

  4. Byproduct aggregate. Copper slag aggregate, ferronickel slag aggregate; Fukusan kotsuzai. Do suragu kotsuzai, fuero nikkeru suragu kotsuzai

    Energy Technology Data Exchange (ETDEWEB)

    Kajiwara, Toshitaka

    1998-08-10

    Copper slag aggregate and ferronickel slag aggregate has not only usual substitute of sand or crushed sand but many features unlike sand or unlike crushed sand. It has many features unlike sand or crushed sand. It seems that especially, behavior of the particulates minute is features of deserving in addition, the examination in future. Of course, one feature also consists on the merit on the demerit by the use. And, copper slag aggregate, ferronickel slag aggregate have also limited the production place at the output of about 2 million annual production tons. These features are utilized, and in addition, wants to teach and want to receive the wider usage. (NEDO)

  5. Natural aggregates of the conterminous United States

    Science.gov (United States)

    Langer, William H.

    1988-01-01

    Crushed stone and sand and gravel are the two main sources of natural aggregates. These materials are commonly used construction materials and frequently can be interchanged with one another. They are widely used throughout the United States, with every State except two producing crushed stone. Together they amount to about half the mining volume in the United States. Approximately 96 percent of sand and gravel and 77 percent of the crushed stone produced in the United States are used in the construction industry. Natural aggregates are widely distributed throughout the United States in a variety of geologic environments. Sand and gravel deposits commonly are the results of the weathering of bedrock and subsequent transportation and deposition of the material by water or ice (glaciers). As such, they commonly occur as river or stream deposits or in glaciated areas as glaciofluvial and other deposits. Crushed stone aggregates are derived from a wide variety of parent bedrock materials. Limestone and other carbonates account for approximately three quarters of the rocks used for crushed stone, with granite and other igneous rocks making up the bulk of the remainder. Limestone deposits are widespread throughout the Central and Eastern United States and are scattered in the West. Granites are widely distributed in the Eastern and Western United States, with few exposures in the Midwest. Igneous rocks (excluding granites) are largely concentrated in the Western United States and in a few isolated localities in the East. Even though natural aggregates are widely distributed throughout the United States, they are not universally available for consumptive use. Some areas are devoid of sand and gravel, and potential sources of crushed stone may be covered with sufficient unconsolidated material to make surface mining impractical. In some areas many aggregates do not meet the physical property requirements for certain uses, or they may contain mineral constituents that react

  6. 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.

  7. 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...

  8. A vertically resolved model for phytoplankton aggregation

    Indian Academy of Sciences (India)

    Iris Kriest; Geoffrey T Evans

    2000-12-01

    This work presents models of the vertical distribution and flux of phytoplankton aggregates, including changes with time in the distribution of aggregate sizes and sinking speeds. The distribution of sizes is described by two parameters, the mass and number of aggregates, which greatly reduces the computational cost of the models. 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 is small, and it presents the difference in timing between settlement of aggregates and fecal pellets.

  9. Aggregates in the Temporal Query Language TQuel,

    Science.gov (United States)

    1987-07-27

    makes it possible to define both standard and unique aggregates in a rigorous way. Ceri and Gottlob present 43 prVPW t TW WRJR V P P V * a translation...from a subset of SQL that includes aggregates into relational algebra, thereby defining an operational semantics for SQL aggregates [Ceri & Gottlob ...Zvi, J. The Time Relational Model. Ph). Diss. Computer Science Department, UCLA, 1982. (Ceri & Gotlob 19851 Ceri, S. and G. Gottlob . Translating SQL

  10. Preferential oxidation of CO in excess H2 over CeO2/CuO catalyst: Effect of calcination temperature

    Institute of Scientific and Technical Information of China (English)

    Zhiming Gao; Ming Zhou; Hao Deng; Yong Yue

    2012-01-01

    Different from the classical configuration CuO/CeO2 catalyst,the inverse configuration CeO2/CuO catalyst (atomic ratio of Ce/Cu=10/100)was prepared by impregnation method.Five calcination temperatures were selected to investigate the interaction between CeO2 and CuO support.It is found that as calcination temperature increased from 500 to 900 ℃,sintering of CeO2 particles on the support occurred together with the diffusion of a portion of Ce4+ ions into CuO crystals,forming solid solution.Formation of interface complex Ce-O-Cu was suggested by TPR measurements.The catalyst calcined at 700℃ gives the highest activity for preferential oxidation of CO in excess H2 stream.

  11. Effect of support calcination temperature on the Ru-Ce-B/ZrO_2 catalysts for benzene selective hydrogenation to cyclohexene

    Institute of Scientific and Technical Information of China (English)

    HAN Jianhua; LI Lichao

    2011-01-01

    The effect of support calcination temperature on the benzene selective hydrogenation performance of the Ru-Ce-B/ZrO2 catalysts was investigated.It was found that with increasing calcination temperature,the surface area decreased,on the contrary,the pore size and the amount of monoclinic phase increased.With increasing support calcination temperature,the activity of the catalyst roughly decreased and cyclohexene selectivity increased.The activity decreased due to the decrease of the surface areas.The increase of the cyclohexene selectivity was correlated not only with the decrease of the surface areas but also with the increase of monoclinic phases,rich in surface hydroxyl,and the enlarged pore size of zirconia.This suggests the monoclinic zirconia with a medium surface area,rather than a big one,and a mesoporous structure,even including some macropores,is an ideal support of the catalyst for benzene selective hydrogenation.

  12. HYDROESTERIFICATION OF ACETYLENE WITH METHYL FORMATE TO METHYL ACRYLATE OVER A NiO/Al203 CATALYST: EFFECTS OF NiO LOADING AND CALCINATION TEMPERATURE

    Institute of Scientific and Technical Information of China (English)

    Huang Xinhan; Yang Xiangui; Zhang Jiaqi; Liu Zhaotie

    2001-01-01

    Hydroesterification of acetylene with methyl formate (MF) was studied over a series of nickel-supported catalysts with NiO loading varing from 0.8 wt% to 18.7 wt% and calcination temperature ranging from 623 K to 873 K. The catalyst was studied by TPR, XPS, XRD and BET. The interactions between impregnated Ni2+ and alumina during catalyst preparation produced different kinds of nickel species such as NiO crystallites and NiAl2O4-like species, and their distributions varied with NiO loading and calcination temperature, which leads to different activities of catalyst in hydroesterification of acetylene with methyl formate. Experimental results indicated that 10wt% NiO/Al2O3 calcined at 773 K is suitable for the hydroesterification of acetylene with methyl formate.

  13. 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.

  14. Aggregate growth in a protoplanetary disk

    Science.gov (United States)

    Xiang, Chuchu; Carballido, Augusto; Matthews, Lorin; Hyde, Truell

    2017-01-01

    We present a method to model the growth of neutral and charged dusts in a turbulent protoplanetary disk, and analyze their collision probabilities. Coagulation of dust aggregates plays an important role in the formation of planets and is of key importance to the evolution of protoplanetary disks. In our method, the temporal evolution of the dusts is followed by Monte Carlo algorithm, and the inter-particle interactions are calculated by Aggregate_Builder (AB), which is a code used to model the collision process of aggregates. First an aggregate library is built and all the aggregates are binned according to their sizes. In each iteration, the collision rate for aggregates from any two bins are computed, which determines the time it takes for the next collision to happen and which two aggregates are selected for collision. Then the AB codes are used to calculate the interaction of the two aggregates. The relative velocity between the two aggregates is the vector sum of Brownian velocity and the turbulent velocity. The latter is calculated by ATHENA, which is a grid-based code for astrophysical magnetohydrodynamics. In each iteration, it’s determined whether the two aggregates hit or miss. In the case of hit, it either sticks or bounces as determined by the critical velocity. As a result, the neutral aggregates are more porous than the charged ones. For a certain size of incoming aggregates, the neutral ones have a higher collision probability than the charged ones. Also, similarly-sized aggregates have lower collision probabilities than aggregates with large size dispersions. This research enables us to determine which physical properties have a greater impact on the collision rate. By tracing the dust size distribution, we can identify the stage when they settle out to the mid-plane and how long it takes to develop to that stage. In the hit-stick regime, our results are consistent with the experiments which shows that when the velocity is smaller than the

  15. 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.

  16. Population balance modeling of antibodies aggregation kinetics.

    Science.gov (United States)

    Arosio, Paolo; Rima, Simonetta; Lattuada, Marco; Morbidelli, Massimo

    2012-06-21

    The aggregates morphology and the aggregation kinetics of a model monoclonal antibody under acidic conditions have been investigated. Growth occurs via irreversible cluster-cluster coagulation forming compact, fractal aggregates with fractal dimension of 2.6. We measured the time evolution of the average radius of gyration, , and the average hydrodynamic radius, , by in situ light scattering, and simulated the aggregation kinetics by a modified Smoluchowski's population balance equations. The analysis indicates that aggregation does not occur under diffusive control, and allows quantification of effective intermolecular interactions, expressed in terms of the Fuchs stability ratio (W). In particular, by introducing a dimensionless time weighed on W, the time evolutions of measured under various operating conditions (temperature, pH, type and concentration of salt) collapse on a single master curve. The analysis applies also to data reported in the literature when growth by cluster-cluster coagulation dominates, showing a certain level of generality in the antibodies aggregation behavior. The quantification of the stability ratio gives important physical insights into the process, including the Arrhenius dependence of the aggregation rate constant and the relationship between monomer-monomer and cluster-cluster interactions. Particularly, it is found that the reactivity of non-native monomers is larger than that of non-native aggregates, likely due to the reduction of the number of available hydrophobic patches during aggregation.

  17. 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)....

  18. Collisional Aggregation due to Turbulence

    CERN Document Server

    Pumir, Alain

    2015-01-01

    Collisions between particles suspended in a fluid play an important role in many physical processes. As an example, collisions of microscopic water droplets in clouds are a necessary step in the production of macroscopic raindrops. Collisions of dust grains are also conjectured to be important for planet formation in the gas surrounding young stars, and also to play a role in the dynamics of sand storms. In these processes, collisions are favoured by fast turbulent motions. Here we review recent advances in the understanding of collisional aggregation due to turbulence. We discuss the role of fractal clustering of particles, and caustic singularities of their velocities. We also discuss limitations of the Smoluchowski equation for modelling these processes. These advances lead to a semi-quantitative understanding on the influence of turbulence on collision rates, and point to deficiencies in the current understanding of rainfall and planet formation.

  19. Morphological classification of nanoceramic aggregates

    Science.gov (United States)

    Crosta, Giovanni F.; Kang, Bongwoo; Ospina, Carolina; Sung, Changmo

    2005-01-01

    Aluminum silicate nanoaggregates grown at near-room temperature on an organic template under a variety of experimental conditions have been imaged by transmission electron microscopy. Images have been automatically classified by an algorithm based on "spectrum enhancement", multivariate statistics and supervised optimization. Spectrum enhancement consists of subtracting, in the log scale, a known function of wavenumber from the angle averaged power spectral density of the image. Enhanced spectra of each image, after polynomial interpolation, have been regarded as morphological descriptors and as such submitted to principal components analysis nested with a multiobjective parameter optimization algorithm. The latter has maximized pairwise discrimination between classes of materials. The role of the organic template and of a reaction parameter on aggregate morphology has been assessed at two magnification scales. Classification results have also been related to crystal structure data derived from selected area electron diffraction patterns.

  20. Colloid Release from Soil Aggregates

    DEFF Research Database (Denmark)

    Vendelboe, Anders Lindblad; Møldrup, Per; Schjønning, Per;

    2012-01-01

    The content of water-dispersible colloids (WDC) has a major impact on soil functions and structural stability. In addition, the presence of mobile colloids may increase the risk of colloid-facilitated transport of strongly sorbing environmental contaminants. The WDC content was measured in 39 soils......, using laser diffraction, by agitating the samples using a wet-dispersion unit. This approach eliminated the need for long sedimentation times required by the more classical end-over-end shaking approach and provided information about the time-dependent release of WDC. The total clay content of the soils...... ranged from 0.1 to 0.44 kg kg−1. The WDC content was measured on air-dry and moist 1- to 2-mm aggregates. The WDC content at a reference time was highly correlated to the total clay content (r > 0.91, P soils. Only for two sites was the WDC content correlated to the content of clay...

  1. Thrombolytic therapy reduces red blood cell aggregation in plasma without affecting intrinsic aggregability.

    Science.gov (United States)

    Ben-Ami, R; Sheinman, G; Yedgar, S; Eldor, A; Roth, A; Berliner, A S; Barshtein, G

    2002-03-15

    Red blood cell (RBC) aggregation may contribute to occlusion of the coronary microcirculation during myocardial infarction. We studied the effect of thrombolytic therapy on RBC aggregation in patients with acute myocardial infarction (AMI). Compared with patients with myocardial infarction who did not receive thrombolytic therapy, those treated with systemic thrombolysis exhibited significantly reduced RBC aggregation, reduced plasma fibrinogen levels and increased plasma D-dimer levels. Using measurement of RBC aggregation in a standardized dextran-500 solution, reduction in RBC aggregation after thrombolysis was shown to be plasma dependent. Thrombolytic therapy had no direct effect on intrinsic RBC aggregability in patients with AMI. We conclude that thrombolytic therapy has rheologic consequences that may contribute to its overall efficacy. Inhibition of RBC aggregation by thrombolytic therapy may result from the degradation of fibrinogen, a key factor in the formation of RBC aggregates, and from the generation of fibrinogen degradation products capable of disaggregating RBCs.

  2. Transesterification of edible, non-edible and used cooking oils for biodiesel production using calcined layered double hydroxides as reusable base catalysts.

    Science.gov (United States)

    Sankaranarayanan, Sivashunmugam; Antonyraj, Churchil A; Kannan, S

    2012-04-01

    Fatty acid methyl esters (FAME) were produced from edible, non-edible and used cooking oils with different fatty acid contents by transesterification with methanol using calcined layered double hydroxides (LDHs) as solid base catalysts. Among the catalysts, calcined CaAl2-LDH (hydrocalumite) showed the highest activity with >90% yield of FAME using low methanol:oil molar ratio (catalyzed process for production of biodiesel in high yields from a wide variety of triglyceride oils including used oils is possible using optimized conditions.

  3. Study on X-ray diffraction and finger print of Calcined Borax%煅硼砂X射线衍射指纹图谱研究

    Institute of Scientific and Technical Information of China (English)

    赵翠; 张倩; 周平; 王伯涛

    2012-01-01

    Objective: To establish fingerprint of Calcined Borax, and to provide a new method for evaluating the quality of Calcined Borax. Methods: Adopting X-ray diffraction techniques to analyze Calcined Borax qualitatively and comparing the semblance of the public peaks. Results: Obtaining X-ray diffraction patterns of 8 samples about Calcined Borax, the geometric and topological characteristics of 7 samples is consistent. Using the X-ray diffraction patterns of that 7 samples obtain X-ray diffraction fingerprint of Calcined Borax. And accord to the fingerprints and the intensity of each characteristic peak in X-ray diffraction patterns of Calcined Borax to calculate the similarity of different samples which use the cosine law and the correlation coefficient method. We found that similarity of common peaks in different samples of X-ray diffraction pattern is high, which is consistent with the results of the cluster analysis. Conclusion: For analysis of calcined borax it has good specificity and feasible by X-ray diffraction fingerprint and it can be used to distinguish and evaluate Calcined Borax.%目的:建立中药煅硼砂X射线衍射指纹图谱,为煅硼砂质量评价提供新方法.方法:采用X射线衍射技术对煅硼砂样品进行定性分析,并对各样品共有峰进行相似度分析.结果:获得了8个煅硼砂样品的X射线衍射图谱,其中7个样品衍射图谱几何拓扑特征基本一致;利用该7批煅硼砂样品X衍射图谱得到煅硼砂的X射线衍射指纹图谱;并以指纹图谱为对照,根据煅硼砂X射线衍射图谱中各特征峰峰高强度,以夹角余弦法和相关系数法计算各样品X射线衍射图谱的相似度,发现不同样品X射线衍射图谱共有峰相似度均较高,与聚类分析结果一致.结论:X射线衍射指纹图谱分析方法专属性强,准确可靠,可实现对煅硼砂的鉴别和质量评价.

  4. 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

    2017-02-01

    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.

  5. Preformed Seeds Modulate Native Insulin Aggregation Kinetics.

    Science.gov (United States)

    Dutta, Colina; Yang, Mu; Long, Fei; Shahbazian-Yassar, Reza; Tiwari, Ashutosh

    2015-12-10

    Insulin aggregates under storage conditions via disulfide interchange reaction. It is also known to form aggregates at the site of repeated injections in diabetes patients, leading to injection amyloidosis. This has fueled research in pharmaceutical and biotechnology industry as well as in academia to understand factors that modulate insulin stability and aggregation. The main aim of this study is to understand the factors that modulate aggregation propensity of insulin under conditions close to physiological and measure effect of "seeds" on aggregation kinetics. We explored the aggregation kinetics of insulin at pH 7.2 and 37 °C in the presence of disulfide-reducing agent dithiothreitol (DTT), using spectroscopy (UV-visible, fluorescence, and Fourier transform infrared spectroscopy) and microscopy (scanning electron microscopy, atomic force microscopy) techniques. We prepared insulin "seeds" by incubating disulfide-reduced insulin at pH 7.2 and 37 °C for varying lengths of time (10 min to 12 h). These seeds were added to the native protein and nucleation-dependent aggregation kinetics was measured. Aggregation kinetics was fastest in the presence of 10 min seeds suggesting they were nascent. Interestingly, intermediate seeds (30 min to 4 h incubation) resulted in formation of transient fibrils in 4 h that converted to amorphous aggregates upon longer incubation of 24 h. Overall, the results show that insulin under disulfide reducing conditions at pH and temperature close to physiological favors amorphous aggregate formation and seed "maturity" plays an important role in nucleation dependent aggregation kinetics.

  6. Impact of Particle Aggregation on Nanoparticle Reactivity

    Science.gov (United States)

    Jassby, David

    2011-12-01

    The prevalence of nanoparticles in the environment is expected to grow in the coming years due to their increasing pervasiveness in consumer and industrial applications. Once released into the environment, nanoparticles encounter conditions of pH, salinity, UV light, and other solution conditions that may alter their surface characteristics and lead to aggregation. The unique properties that make nanoparticles desirable are a direct consequence of their size and increased surface area. Therefore, it is critical to recognize how aggregation alters the reactive properties of nanomaterials, if we wish to understand how these properties are going to behave once released into the environment. The size and structure of nanoparticle aggregates depend on surrounding conditions, including hydrodynamic ones. Depending on these conditions, aggregates can be large or small, tightly packed or loosely bound. Characterizing and measuring these changes to aggregate morphology is important to understanding the impact of aggregation on nanoparticle reactive properties. Examples of decreased reactivity due to aggregation include the case where tightly packed aggregates have fewer available surface sites compared to loosely packed ones; also, photocatalytic particles embedded in the center of large aggregates will experience less light when compared to particles embedded in small aggregates. However, aggregation also results in an increase in solid-solid interfaces between nanoparticles. This can result in increased energy transfer between neighboring particles, surface passivation, and altered surface tension. These phenomena can lead to an increase in reactivity. The goal of this thesis is to examine the impacts of aggregation on the reactivity of a select group of nanomaterials. Additionally, we examined how aggregation impacts the removal efficiency of fullerene nanoparticles using membrane filtration. The materials we selected to study include ZnS---a metal chalcogenide

  7. 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.

  8. Protein aggregation and lyophilization: Protein structural descriptors as predictors of aggregation propensity

    OpenAIRE

    Roughton, Brock C.; Iyer, Lavanya K.; Bertelsen, Esben; Topp, Elizabeth M.; Camarda, Kyle V.

    2013-01-01

    Lyophilization can induce aggregation in therapeutic proteins, but the relative importance of protein structure, formulation and processing conditions are poorly understood. To evaluate the contribution of protein structure to lyophilization-induced aggregation, fifteen proteins were co-lyophilized with each of five excipients. Extent of aggregation following lyophilization, measured using size-exclusion chromatography, was correlated with computational and biophysical protein structural desc...

  9. 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.)

  10. 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

  11. Report for the HWMA/RCRA Post Closure Permit for the INTEC Waste Calcining Facility at the INL Site

    Energy Technology Data Exchange (ETDEWEB)

    Idaho Cleanup Project

    2006-06-01

    The Waste Calcining Facility (WCF) is located at the Idaho Nuclear Technology and Engineering Center. In 1998, the WCF was closed under an approved Hazardous Waste Management Act/Resource Conservation and Recovery Act (HWMA/RCRA) Closure Plan. Vessels and spaces were grouted and then covered with a concrete cap. The Idaho Department of Environmental Quality issued a final HWMA/RCRA post-closure permit on September 15, 2003, with an effective date of October 16, 2003. This permit sets forth procedural requirements for groundwater characterization and monitoring, maintenance, and inspections of the WCF to ensure continued protection of human health and the environment. The post-closure permit also includes semiannual reporting requirements under Permit Conditions III.H. and I.U. These reporting requirements have been combined into this single semiannual report.

  12. New ceramic membranes from calcinated clay; Nouveaux supports membranaires a base de chamotte d'argile

    Energy Technology Data Exchange (ETDEWEB)

    El Moudden, N.; El Ghazouali, A.; Rakib, S.; Sghyar, M.; Rafiq, M. [Faculte des Sciences, Lab. des Materiaux et Protection de L' environnement, Fes Atlas (Morocco); Larbot, A.; Cot, L. [Laboratoire des Materiaux et Procedes Membranaires, UMR 5635-CNRS, ENSCM UM, 34 - Montpellier (France)

    2001-04-01

    The aim of the present work is to obtain porous tubular ceramic membranes from natural material. The clay powders were calcinated in air at 900 deg C for two hours. The resulting powders mixed with certain organic additives could be extruded to fabricate a porous tubular configuration with highly uniform porous structures. The mean pore diameter, measured by mercury porosimetry, is equal to 9 {mu}m and the porosity is 38% (heat treatment at 1130 deg C for two hours). Many ceramic membrane manufactures have used this type of large-pore membrane as supports for finer-pore membranes (micro-filtration or ultrafiltration). Porous membranes possess very good mechanical strength and negligible flow resistance for the membrane/support, while containing pores which allow a high degree of permeation. (authors)

  13. Hydrothermal conversion of FAU zeolite into LEV zeolite in the presence of non-calcined seed crystals

    Science.gov (United States)

    Yashiki, Ayako; Honda, Koutaro; Fujimoto, Ayumi; Shibata, Shohei; Ide, Yusuke; Sadakane, Masahiro; Sano, Tsuneji

    2011-06-01

    Hydrothermal conversion of Faujasite-type (FAU) zeolite into Levynite (LEV) zeolite without the use of an organic structure-directing agent (OSDA) was successfully achieved in the presence of non-calcined seed crystals. The interzeolite conversion depended strongly upon the alkalinity (OH -/SiO 2) of the starting gel, the Si/Al ratio of the starting FAU zeolite and the type of alkaline metal employed. Successful conversion of FAU zeolites into pure LEV zeolite was achieved only for FAU zeolites with Si/Al ratios in the range of 19-26, under highly alkaline conditions (OH -/SiO 2=0.6) by using NaOH as an alkali source. Although the yield of LEV zeolite prepared by this method was lower (18-26%) than that of the conventional hydrothermal synthesis with the use of SDA, the obtained LEV zeolite exhibited a unique core/shell structure.

  14. 循环率对循环流化床分解炉性能的影响%Effect of recirculation ratio on the operation of CFB calciners

    Institute of Scientific and Technical Information of China (English)

    李辉; 徐德龙; 冯绍航; 陈延信

    2005-01-01

    流化床反应器在水泥工业用于生料的预分解.为了提高物料分解率,开发出一种新型的循环流化床反应器并已用于水泥生产.这种循环流化床反应器中的固气比要高于传统的预分解反应器.在建立物料氧化钙平衡的基础上,建立了关于物料循环率和碳酸盐分解率之间相互关系的数学模型.模型的计算结果与现场测试结果吻合很好.此外还提出了分解炉热稳定性的概念,并给出了相应热稳定系数的表达式.结果证明:使用循环流化床分解炉可有效改进固体物料的最终分解率.当操作温度一定(850℃)时,循环率每增加100%,入窑物料的终分解率可提高8%~9%.外循环方案有助于改善分解炉的热稳定性并降低分解炉的操作温度;在终分解率不变的情况下,物料循环率每增加100%,分解炉的操作温度可降低30~50℃.%Fluidized bed reactors have been used as calciners in cement industry for calcination of cement raw meal.Aiming at enhancing calcining rate, a new kind of circulating fluidized bed(CFB) reactor was developed and applied in cement plants. Inside this kind of CFB reactor, the mass ratio of solid to gas (S/G) was much higher than traditional one. Based on the balance of calcium oxide material, a mathematical model concerning the relationship between recirculation ratio of material and calcining rate of carbonate was developed. The computing results by using such relationship showed reasonable agreement with experiments. The concept of thermal stability of calciner was put forwarded, and the corresponding mathematical expression of thermal stability coefficient was determined. It was proved that application of CFB calciner improved the final calcination degree of solid material. At fixed operating temperature (850 ℃), the calcining rate of the carbonate into rotary kiln may be enhanced by 8%~9% with 100%increase of recirculation ratio. Meanwhile application of external re

  15. Marine particle aggregate breakup in turbulent flows

    Science.gov (United States)

    Rau, Matthew; Ackleson, Steven; Smith, Geoffrey

    2016-11-01

    The dynamics of marine particle aggregate formation and breakup due to turbulence is studied experimentally. Aggregates of clay particles, initially in a quiescent aggregation tank, are subjected to fully developed turbulent pipe flow at Reynolds numbers of up to 25,000. This flow arrangement simulates the exposure of marine aggregates in coastal waters to a sudden turbulent event. Particle size distributions are measured by in-situ sampling of the small-angle forward volume scattering function and the volume concentration of the suspended particulate matter is quantified through light attenuation measurements. Results are compared to measurements conducted under laminar and turbulent flow conditions. At low shear rates, larger sized particles indicate that aggregation initially governs the particle dynamics. Breakup is observed when large aggregates are exposed to the highest levels of shear in the experiment. Models describing the aggregation and breakup rates of marine particles due to turbulence are evaluated with the population balance equation and results from the simulation and experiment are compared. Additional model development will more accurately describe aggregation dynamics for remote sensing applications in turbulent marine environments.

  16. 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…

  17. A formal approach to aggregated belief formation

    NARCIS (Netherlands)

    Heuvelink, A.; Klein, M.C.A.; Treur, J.

    2008-01-01

    This paper introduces a formal method to aggregate over basic beliefs, in order to deduce aggregated or complex beliefs as often used in applications. Complex beliefs can represent several things, such as a belief about a period in which other beliefs held or the minimal or maximal certainty with wh

  18. Approximation of Aggregate Losses Using Simulation

    Directory of Open Access Journals (Sweden)

    Mohamed A. Mohamed

    2010-01-01

    Full Text Available Problem statement: The modeling of aggregate losses is one of the main objectives in actuarial theory and practice, especially in the process of making important business decisions regarding various aspects of insurance contracts. The aggregate losses over a fixed time period is often modeled by mixing the distributions of loss frequency and severity, whereby the distribution resulted from this approach is called a compound distribution. However, in many cases, realistic probability distributions for loss frequency and severity cannot be combined mathematically to derive the compound distribution of aggregate losses. Approach: This study aimed to approximate the aggregate loss distribution using simulation approach. In particular, the approximation of aggregate losses was based on a compound Poisson-Pareto distribution. The effects of deductible and policy limit on the individual loss as well as the aggregate losses were also investigated. Results: Based on the results, the approximation of compound Poisson-Pareto distribution via simulation approach agreed with the theoretical mean and variance of each of the loss frequency, loss severity and aggregate losses. Conclusion: This study approximated the compound distribution of aggregate losses using simulation approach. The investigation on retained losses and insurance claims allowed an insured or a company to select an insurance contract that fulfills its requirement. In particular, if a company wants to have an additional risk reduction, it can compare alternative policies by considering the worthiness of the additional expected total cost which can be estimated via simulation approach.

  19. 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...

  20. Familial Aggregation and Childhood Blood Pressure

    NARCIS (Netherlands)

    Wang, Xiaoling; Xu, Xiaojing; Su, Shaoyong; Snieder, Harold

    2015-01-01

    There is growing concern about elevated blood pressure (BP) in children. The evidence for familial aggregation of childhood BP is substantial. Twin studies have shown that a large part of the familial aggregation of childhood BP is due to genes. The first part of this review provides the latest prog

  1. 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...

  2. Multicandidate Elections: Aggregate Uncertainty in the Laboratory*

    Science.gov (United States)

    Bouton, Laurent; Castanheira, Micael; Llorente-Saguer, Aniol

    2015-01-01

    The rational-voter model is often criticized on the grounds that two of its central predictions (the paradox of voting and Duverger’s Law) are at odds with reality. Recent theoretical advances suggest that these empirically unsound predictions might be an artifact of an (arguably unrealistic) assumption: the absence of aggregate uncertainty about the distribution of preferences in the electorate. In this paper, we propose direct empirical evidence of the effect of aggregate uncertainty in multicandidate elections. Adopting a theory-based experimental approach, we explore whether aggregate uncertainty indeed favors the emergence of non-Duverger’s law equilibria in plurality elections. Our experimental results support the main theoretical predictions: sincere voting is a predominant strategy under aggregate uncertainty, whereas without aggregate uncertainty, voters massively coordinate their votes behind one candidate, who wins almost surely.

  3. Role of multicellular aggregates in biofilm formation

    DEFF Research Database (Denmark)

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

    2016-01-01

    response, may add to this ecological benefit. Our findings suggest that current models of biofilm formation should be reconsidered to incorporate the role of aggregates in biofilm initiation.IMPORTANCE During the past decades, there has been a consensus around the model of development of a biofilm......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...

  4. Formation of Tethers from Spreading Cellular Aggregates.

    Science.gov (United States)

    Beaune, Grégory; Winnik, Françoise M; Brochard-Wyart, Françoise

    2015-12-01

    Membrane tubes are commonly extruded from cells and vesicles when a point-like force is applied on the membrane. We report here the unexpected formation of membrane tubes from lymph node cancer prostate (LNCaP) cell aggregates in the absence of external applied forces. The spreading of LNCaP aggregates deposited on adhesive glass substrates coated with fibronectin is very limited because cell-cell adhesion is stronger than cell-substrate adhesion. Some cells on the aggregate periphery are very motile and try to escape from the aggregate, leading to the formation of membrane tubes. Tethered networks and exchange of cargos between cells were observed as well. Growth of the tubes is followed by either tube retraction or tube rupture. Hence, even very cohesive cells are successful in escaping aggregates, which may lead to epithelial mesenchymal transition and tumor metastasis. We interpret the dynamics of formation and retraction of tubes in the framework of membrane mechanics.

  5. 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...... computations of aggregate values. The paper also reports on the experiments with the methods. The work is motivated with a real-world case study, based on our collaboration with a leading Danish vendor of location-based services. No previous work considers the combination of the aspects of uncertain...

  6. Spatial Aggregation: Data Model and Implementation

    CERN Document Server

    Gomez, Leticia; Kuijpers, Bart; Vaisman, Alejandro

    2007-01-01

    Data aggregation in Geographic Information Systems (GIS) is only marginally present in commercial systems nowadays, mostly through ad-hoc solutions. In this paper, we first present a formal model for representing spatial data. This model integrates geographic data and information contained in data warehouses external to the GIS. We define the notion of geometric aggregation, a general framework for aggregate queries in a GIS setting. We also identify the class of summable queries, which can be efficiently evaluated by precomputing the overlay of two or more of the thematic layers involved in the query. We also sketch a language, denoted GISOLAP-QL, for expressing queries that involve GIS and OLAP features. In addition, we introduce Piet, an implementation of our proposal, that makes use of overlay precomputation for answering spatial queries (aggregate or not). Our experimental evaluation showed that for a certain class of geometric queries with or without aggregation, overlay precomputation outperforms R-tre...

  7. Aggregation of Composite Solutions: strategies, models, examples

    CERN Document Server

    Levin, Mark Sh

    2011-01-01

    The paper addresses aggregation issues for composite (modular) solutions. A systemic view point is suggested for various aggregation problems. Several solution structures are considered: sets, set morphologies, trees, etc. Mainly, the aggregation approach is targeted to set morphologies. The aggregation problems are based on basic structures as substructure, superstructure, median/consensus, and extended median/consensus. In the last case, preliminary structure is built (e.g., substructure, median/consensus) and addition of solution elements is considered while taking into account profit of the additional elements and total resource constraint. Four aggregation strategies are examined: (i) extension strategy (designing a substructure of initial solutions as "system kernel" and extension of the substructure by additional elements); (ii) compression strategy (designing a superstructure of initial solutions and deletion of some its elements); (iii) combined strategy; and (iv) new design strategy to build a new s...

  8. Excited-state dynamics of astaxanthin aggregates

    Science.gov (United States)

    Fuciman, Marcel; Durchan, Milan; Šlouf, Václav; Keşan, Gürkan; Polívka, Tomáš

    2013-05-01

    Astaxanthin forms three types of aggregates in hydrated dimethyl sulfoxide (DMSO). In DMSO/water ratio of 1:1, a red-shifted J-aggregate with maximum at 570 nm is generated, while a ratio of 1:9 produces blue-shifted H-aggregates with peaks at 386 nm (H1) and 460 nm (H2). Monomeric astaxanthin in DMSO has an S1 lifetime of 5.3 ps, but a long-lived (33 ps) S∗ signal was also identified. Aggregation changes the S1 lifetimes to 17 ps (H1), 30 ps (H2), and 14 ps (J). Triplet state of astaxanthin, most likely generated via singlet homofission, was observed in H1 and H2 aggregates.

  9. An exact approach for aggregated formulations

    DEFF Research Database (Denmark)

    Gamst, Mette; Spoorendonk, Simon

    optimality cannot be guaranteed by branching on the aggregated variables. In this presentation, we propose a general method for solving aggregated formulations, such that the solution is optimal to the original problem. The method is based on applying Benders’ decomposition on a combination of the original...... to mathematical formulations with a different solution space than that for the original formulation, i.e., the aggregated formulation may be a relaxation of the original problem. In a branch-and-bound context, variable aggregation can also lead to a formulation where branching is not trivial, for example when...... and aggregated formulations. Put in a branch-and-bound context, branching can be performed on the original variables to ensure optimality. We show how to apply the method on well-known optimization problems....

  10. The fractal aggregation of asphaltenes.

    Science.gov (United States)

    Hoepfner, Michael P; Fávero, Cláudio Vilas Bôas; Haji-Akbari, Nasim; Fogler, H Scott

    2013-07-16

    This paper discusses time-resolved small-angle neutron scattering results that were used to investigate asphaltene structure and stability with and without a precipitant added in both crude oil and model oil. A novel approach was used to isolate the scattering from asphaltenes that are insoluble and in the process of aggregating from those that are soluble. It was found that both soluble and insoluble asphaltenes form fractal clusters in crude oil and the fractal dimension of the insoluble asphaltene clusters is higher than that of the soluble clusters. Adding heptane also increases the size of soluble asphaltene clusters without modifying the fractal dimension. Understanding the process of insoluble asphaltenes forming fractals with higher fractal dimensions will potentially reveal the microscopic asphaltene destabilization mechanism (i.e., how a precipitant modifies asphaltene-asphaltene interactions). It was concluded that because of the polydisperse nature of asphaltenes, no well-defined asphaltene phase stability envelope exists and small amounts of asphaltenes precipitated even at dilute precipitant concentrations. Asphaltenes that are stable in a crude oil-precipitant mixture are dispersed on the nanometer length scale. An asphaltene precipitation mechanism is proposed that is consistent with the experimental findings. Additionally, it was found that the heptane-insoluble asphaltene fraction is the dominant source of small-angle scattering in crude oil and the previously unobtainable asphaltene solubility at low heptane concentrations was measured.

  11. Effect of calcination temperature on physical parameters and photocatalytic activity of mesoporous titania spheres using chitosan/poly(vinyl alcohol) hydrogel beads as a template

    Science.gov (United States)

    Jiang, R.; Zhu, H.-Y.; Chen, H.-H.; Yao, J.; Fu, Y.-Q.; Zhang, Z.-Y.; Xu, Y.-M.

    2014-11-01

    Mesoporous titania spheres were prepared by modified sol-gel method using chitosan/poly(vinyl alcohol) hydrogel beads as a template. Effects of calcination temperature on physical parameters were investigated by X-ray diffraction (XRD), N2 adsorption-desorption, Fourier transform infrared (FT-IR) spectra, thermogravimetry and differential thermal analyses (TG-DTA), high-resolution transmission electron microscope (HRTEM) and scanning electron microscopy (SEM). The photocatalytic activity of mesoporous titania spheres prepared was also evaluated by photocatalytic degradation of phenol as a model molecule under UV irradiation. With increasing calcination temperature, average crystallite size and pore size increased. In contrast, Brunauer-Emmett-Teller (BET) specific surface areas, porosity and pore volumes steadily decreased. Results of characterization proved that prepared titania spheres with highly organized pores were mesoporous structure. The photocatalytic activity of mesoporous titania spheres calcined at 500 °C was more effective than those calcined at other temperatures, which were attributed to the porous structure, large BET surface area, crystalline, and smaller crystallite size. This work may provide new insights into the preparation of novel mesoporous titania spheres and further practical applications in the treatment of wastewater.

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

    KAUST Repository

    Rakhi, R. B.

    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.

  13. Influence of lithium precursors and calcination atmospheres on graphene sheets-modified nano-Li4Ti5O12 anode material

    Science.gov (United States)

    Li, Wen-Ting; Yuan, Tao; Zhang, Weimin; Ma, Jingjing; Zhang, Chunming; He, Yu-Shi; Liao, Xiao-Zhen; Ma, Zi-Feng

    2015-07-01

    The influence of Li precursors and calcination atmospheres on the reaction mechanisms, physical properties and electrochemical performance of graphene sheets (GS)-modified nano-Li4Ti5O12 (LTO/GS) has been systematically investigated. Field emission scanning electron microscopy (FE-SEM) and mass spectrometry (MS) results demonstrate the lithium precursor containing carboxyl anion such as lithium acetate (LiAc) and Li2CO3 interact with oxygen groups of graphene oxide (GO) by strong hydrogen bonds to restrict the morphology and the phase formation of products. We also notice from the thermogravimetry (TG) and MS results that the consumption of GS is proportional to oxygen content of lithium precursor. Cyclic voltammetry (CV) and X-ray photoelectric spectroscopy (XPS) results indicate that the product calcined in reducing atmosphere possess smaller electrochemical polarization due to more reduced Ti3+ on the surface of the product. The LTO/GS sample with LiOH as Li precursor calcined in diluted hydrogen atmosphere show the best electrochemical performance with a capacity of 134.4 mAh g-1 at 10C discharge rate and very stable cycling life with a 98.6% capacity retention after 800 cycles at 40C rate. This study not only provides an optimization of Li precursor and calcination condition for LTO/GS anode material, but also guides any future one-step syntheses of lithium composite materials with GO participation.

  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. Synthesis and characterization of Ag@ZnO nanostructures for photocatalytic degradation of rhodamine B: influence of calcination temperature and Ag content

    Science.gov (United States)

    Sun, Yongjiao; Zhao, Zhenting; Li, Gang; Li, Pengwei; Zhang, Wendong; Han, Zhitao; Lian, Kun; Hu, Jie

    2017-02-01

    Hydrangea-like Ag@ZnO nanostructures were synthesized utilizing aqueous solution method, followed by calcination at different temperatures in air. The crystal structure, surface morphology and chemical state of synthesized nanostructures were analyzed. The results showed that hydrangea-like Ag@ZnO architectures exhibited the diameters in the range of 1.54-3.54 μm and decorated with Ag nanoparticles approximately 15 nm. The photocatalytic experiments were conducted on the as-prepared Ag@ZnO samples for photocatalytic degradation of rhodamine B after calcinations from 400 to 900 °C. The measured results demonstrate that both the calcination temperature and the content of Ag can significant influence the photocatalytic activities. Moreover, the 0.5 mol% Ag@ZnO exhibits the highest photocatalytic activity under the optimum calcination temperature of 700 °C. This study indicates that the as-prepared Ag@ZnO nanostructures have promising potential applications in the fields such as photocatalysis, solar energy conversion and sensing detection.

  16. CO and C3H8 total oxidation over Pd/La-Al2O3 catalysts:Effect of calcination temperature and hydrothermal treatment

    Institute of Scientific and Technical Information of China (English)

    周仁美; 邢丰; 王树元; 鲁继青; 金凌云; 罗孟飞

    2014-01-01

    A series of Pd/La-Al2O3 (PLA) catalysts with La-Al2O3 (LA) support calcined at different temperatures (500, 700, 900 and 1050 ºC) were prepared using an incipient wetness impregnation method. The activity of the fresh and hydrothermally aged PLA catalysts were tested for total oxidation of CO and C3H8. The activity of the fresh PLA catalysts for CO and C3H8 oxidation increased with increasing calcination temperature of the support, while the activities of the aged catalysts declined and became essentially the same. CO chemisorption results revealed that the suppressed activities of the aged catalysts were mainly due to the decline of palla-dium dispersion. The turnover frequency (TOF) of CO oxidation increased with increasing reduction ability of the catalysts, with a fresh catalyst calcined at 1050 ºC having the highest value (0.048 s-1). However, the TOF of C3H8 total oxidation was affected by not only the redox properties of catalysts but also the size of Pd particle, and large Pd particles possessed higher TOF value of C3H8 oxi-dation, with the highest value (0.125 s-1) being obtained on an aged catalyst calcined at 500 ºC.

  17. 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.

  18. 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.

  19. Study on process parameters for activating fly ash with alkali by calcination%加碱煅烧活化粉煤灰工艺参数研究

    Institute of Scientific and Technical Information of China (English)

    吴勇勇; 周勇敏; 张苏伊

    2012-01-01

    The calcination process for activating fly ash with Na2CO3 as accessory ingredient was investigated.The concenta-tions of Si and A1 in the fly ash activated under different calcination conditions (calcination temperature and calcination time), that dissolved in the sodium hydroxide solution were measured by titering process.The phase composition of fly ash obtained under different calcination conditions (mass ratio of fly ash and sodium carbonate ) was characterized by XRD.The best process parameters were obtained as follows: calcination temperature was 875 X. .holding time was 1.5 h,and mass ratio of fly ash and sodium carbonate was 1:0.87.The products after calcination were mainly made up of soluble NaAlSiO4 and Na2SiO3,and the quartz and mullitein in the raw fly ash both almost disappeared.Therefore, the fly ash was activated adequately.%研究了以碳酸钠为助剂活化粉煤灰的煅烧工艺.采用滴定法测定不同煅烧条件(煅烧温度和煅烧时间)所得活化粉煤灰溶解在氢氧化钠溶液中的硅、铝浓度,并采用X射线衍射(XRD)表征不同煅烧条件(灰碱质量比)所得活化粉煤灰的物相组成,得出粉煤灰较佳煅烧工艺参数:煅烧温度为875℃,保温时间为1.5 h,粉煤灰与碳酸钠的质量比为1∶0.87.煅烧后的产物主要以可溶性的硅铝酸钠(NaAlSiO4)和硅酸钠(Na2SiO3)为主,原粉煤灰中的石英、莫来石基本消失,粉煤灰得到充分活化.

  20. Aggregate breakup in a contracting nozzle.

    Science.gov (United States)

    Soos, Miroslav; Ehrl, Lyonel; Bäbler, Matthäus U; Morbidelli, Massimo

    2010-01-05

    The breakup of dense aggregates in an extensional flow was investigated experimentally. The flow was realized by pumping the suspension containing the aggregates through a contracting nozzle. Variation of the cluster mass distribution during the breakage process was measured by small-angle light scattering. Because of the large size of primary particles and the dense aggregate structure image analysis was used to determine the shape and structure of the produced fragments. It was found, that neither aggregate structure, characterized by a fractal dimension d(f) = 2.7, nor shape, characterized by an average aspect ratio equal to 1.5, was affected by breakage. Several passes through the nozzle were required to reach the steady state. This is explained by the radial variation of the hydrodynamic stresses at the nozzle entrance, characterized through computational fluid dynamics, which implies that only the fraction of aggregates whose strength is smaller than the local hydrodynamic stress is broken during one pass through the nozzle. Scaling of the steady-state aggregate size as a function of the hydrodynamic stress was used to determine the aggregate strength.

  1. Hardness evaluation of PMMA reinforced with two different calcinations temperatures of ZrO2-Al2O3-SiO2 filler system

    Science.gov (United States)

    Hasratiningsih, Z.; Takarini, V.; Cahyanto, A.; Faza, Y.; Asri, L. A. T. W.; Purwasasmita, B. S.

    2017-02-01

    Polymethyl methacrylate (PMMA) is one of the materials used for the temporary crown while making fixed partial dentures. Unfortunately, it has low mechanical properties. This study aim’s to improve PMMA hardness by adding ZrO2-Al2O3-SiO2 filler system in two different calcination temperatures. Thirty-two disc form samples with 8mm diameter x 3mm thickness were made from two category-filler based that had been previously evaluated using Scanning Electron Microscope (SEM). Each category was divided into six groups of three respectively from a controlled and different concentrations of 7(A), 9(B), 11(C), 13(D), and 15(E) weight % of reinforced filler system, then tested with Vickers Hardness Tester. Filler particles that calcined at 550° can increase to 700° consist of fine crystalline and amorphous phases; however, the sample shows the highest hardness about 20,19 VHN even though the increase is only 7,5% compared to control. Meanwhile, the sample that calcined at 700°C exhibiting the highest hardness about 15,66 VHN corresponds to sample D, it has increased 25% compared to the control. This is correlated with microstructure result that has more growth crystalline particles. The results were analyzed by ANOVA which determined were not statistically significantly different (p<0.05). Therefore, it can be concluded that the 13% reinforced ZrO2-Al2O3-SiO2 filler system calcined at 700°C shows the highest hardness increase compare to calcination temperature 550-700°C. Although it is not significantly different.

  2. Facile synthesis of both needle-like and spherical hydroxyapatite nanoparticles: Effect of synthetic temperature and calcination on morphology, crystallite size and crystallinity

    Energy Technology Data Exchange (ETDEWEB)

    Wijesinghe, W.P.S.L.; Mantilaka, M.M.M.G.P.G. [Department of Chemistry, Faculty of Science, University of Peradeniya, Peradeniya 20400 (Sri Lanka); Post-graduate Institute of Science, P.O. Box: 25, University of Peradeniya, Peradeniya 20400 (Sri Lanka); Premalal, E.V.A. [Department of Materials Science, Shizuoka University, Johoku, Naka-ku Hamamatsu, 432-8011 (Japan); Herath, H.M.T.U. [Department of Medical Laboratory Science, Faculty of Allied Health Sciences, University of Peradeniya, Peradeniya 20400 (Sri Lanka); Mahalingam, S.; Edirisinghe, M. [Department of Mechanical Engineering, University College London, London WC1E 7JE (United Kingdom); Rajapakse, R.P.V.J. [Department of Veterinary Pathobiology, Faculty of Veterinary, University of Peradeniya, Peradeniya 20400 (Sri Lanka); Rajapakse, R.M.G., E-mail: rmgr@pdn.ac.lk [Department of Chemistry, Faculty of Science, University of Peradeniya, Peradeniya 20400 (Sri Lanka); Post-graduate Institute of Science, P.O. Box: 25, University of Peradeniya, Peradeniya 20400 (Sri Lanka)

    2014-09-01

    Synthetic hydroxyapatite (HA) nanoparticles, that mimic natural HA, are widely used as biocompatible coatings on prostheses to repair and substitute human bones. In this study, HA nanoparticles are prepared by precipitating them from a precursor solution containing calcium sucrate and ammonium dihydrogen orthophosphate, at a Ca/P mole ratio of 1.67:1, at temperatures, ranging from 10 °C to 95 °C. A set of products, prepared at different temperatures, is analyzed for their crystallinity, crystallite size, morphology, thermal stability and composition, by X-ray diffraction (XRD), scanning electron microscopy (SEM), thermogravimetric analysis (TGA) and Fourier transform infrared (FT-IR) spectroscopic techniques, while the other set is analyzed after calcining the respective products, soon after their synthesis, for 3 h, at 700 °C. The as-prepared products, after 2 h of drying, without any calcination, are not crystalline, but they grow very slowly into needle-like morphologies, as they are ripened with time. The percentage crystallinity of the final products increases from 15% to 52%, with increasing the preparative temperature. The calcined samples always produce spherical nanoparticles of essentially the same diameter, between 90 nm and 100 nm, which does not change due to aging and preparative temperatures. Therefore, the same method can be utilized to synthesize both spherical and needle-like nanoparticles of hydroxyapatite, with well-defined sizes and shapes. The ability to use readily available cheap raw materials, for the synthesis of such well-defined crystallites of hydroxyapatite, is an added advantage of this method, which may be explored further for the scaling up of the procedures to suit to industrial scale synthesis of such hydroxyapatite nanoparticles. - Highlights: • Hydroxyapatite nanoparticles are synthesized using a simple precipitation method. • Both needle-like and spherical hydroxyapatite nanoparticles are synthesized. • The prepared

  3. Ni/Al2O3 catalysts for CO methanation: Effect of Al2O3 supports calcined at different temperatures

    Institute of Scientific and Technical Information of China (English)

    Jiajian; Gao; Chunmiao; Jia; Jing; Li; Meiju; Zhang; Fangna; Gu; Guangwen; Xu; Ziyi; Zhong; Fabing; Su

    2013-01-01

    The correlation between phase structures and surface acidity of Al2O3 supports calcined at different temperatures and the catalytic performance of Ni/Al2O3 catalysts in the production of synthetic natural gas(SNG) via CO methanation was systematically investigated. A series of 10 wt% NiO/Al2O3 catalysts were prepared by the conventional impregnation method, and the phase structures and surface acidity of Al2O3 supports were adjusted by calcining the commercial γ-Al2O3 at different temperatures(600–1200 C). CO methanation reaction was carried out in the temperature range of 300–600 C at different weight hourly space velocities(WHSV = 30000 and 120000 mL·g-1h-1) and pressures(0.1 and 3.0 MPa). It was found that high calcination temperature not only led to the growth in Ni particle size, but also weakened the interaction between Ni nanoparticles and Al2O3 supports due to the rapid decrease of the specific surface area and acidity of Al2O3 supports. Interestingly, Ni catalysts supported on Al2O3 calcined at 1200 C(Ni/Al2O3-1200) exhibited the best catalytic activity for CO methanation under different reaction conditions. Lifetime reaction tests also indicated that Ni/Al2O3-1200 was the most active and stable catalyst compared with the other three catalysts, whose supports were calcined at lower temperatures(600, 800 and 1000 C). These findings would therefore be helpful to develop Ni/Al2O3 methanation catalyst for SNG production.

  4. Aggregate Formed by a Cationic Fluorescence Probe

    Institute of Scientific and Technical Information of China (English)

    TIAN, Juan; SANG, Da-Yong; JI, Guo-Zhen

    2007-01-01

    The aggregation behavior of a cationic fluorescence probe 10-(4,7,10,13,16-pentaoxa-1-azacyclooctadecyl-methyl)anthracen-9-ylmethyl dodecanoate (1) was observed and studied by a fluorescence methodology in acidic and neutral conditions. By using the Py scale, differences between simple aggregates and micelles have been discussed. The stability of simple aggregates was discussed in terms of hydrophobic interaction and electrostatic repulsion. The absence of excimer emission of the anthrancene moiety of probe 1 in neutral condition was attributed to the photoinduced electron transfer mechanism instead of photodimerization.

  5. Ratio-Based Gradual Aggregation of Data

    DEFF Research Database (Denmark)

    Iftikhar, Nadeem

    2012-01-01

    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 ma....... 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....

  6. Linear aggregation theory in cell biology

    Energy Technology Data Exchange (ETDEWEB)

    Hill, T.L.

    1987-01-01

    This is an account of the theory, probability, and thermodynamics of linear aggregation. The emphasis is on basic principles illustrated by simple models, not on particular applications or polymers. The general physical aggregate systems - attached single-stranded polymers, single-stranded polymers modified by a second component, long multistranded polymers, attached multistranded polymers - are given extensive treatment. Also included are a discussion of the GTPase and ATPase activity accompanying the aggregation of microtubules and action, and the properties of the kinetic two-phase model of the end of a microtubule.

  7. Directional sensing and streaming in Dictyostelium aggregation.

    Science.gov (United States)

    Almeida, Sofia; Dilão, Rui

    2016-05-01

    We merge the Kessler-Levine simple discrete model for Dictyostelium cyclic adenosine monophosphate (cAMP) production and diffusion with the Dilão-Hauser directional sensing aggregation mechanism. The resulting compound model describes all the known transient patterns that emerge during Dictyostelium aggregation, which include the spontaneous formation of cAMP self-sustained target and spiral waves and streaming. We show that the streaming patterns depend on the speed of the amoebae, on the relaxation time for the production of cAMP, on the cAMP degradation rate, and on directional sensing. Moreover, we show that different signaling centers emerge during Dictyostelium aggregation.

  8. 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...... experience. Under the scenarios considered here, the "macro-Mincer" (log-linear) relationship between aggregate human capital and average years of schooling is obtained only in cases which are inconsistent with heterogeneity in years of schooling and based on empirically implausible demographic survival laws...

  9. 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

  10. Acid Resistance of Concrete Containing Laterite Aggregate as Partial Coarse Aggregate Replacement

    Directory of Open Access Journals (Sweden)

    K. Muthusamy

    2014-05-01

    Full Text Available In Malaysia, issues of granite aggregate depletion in future due to increasing use in concrete industry and the availability of laterite aggregate locally has initiated studies on concrete produced using laterite aggregate as partial coarse aggregate replacement. Although, replacement of laterite aggregate up to 30% able to produce concrete with the targeted strength but durability of this concrete towards acid attack yet to be investigated. Thus, this study presents and discusses the performance of concrete consisting various percentage of laterite aggregate integrated as partial coarse aggregate replacement upon exposure to acidic environment. Mixes consisting various content of laterite aggregate as partial coarse aggregate replacement ranging from 0, 10, 20, 30, 40 and 50%, respectively were prepared in form of cubes and then subjected to water curing for 28 days before immersed in hydrochloric acid solution for 1800 h. Performance of the specimens were observed through mass loss and strength reduction. Generally, durability performance of concrete produced using up to 20% of laterite aggregate is comparable to plain concrete.

  11. 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.

  12. Structure and kinetics of shear aggregation in turbulent flows. I. Early stage of aggregation.

    Science.gov (United States)

    Bäbler, Matthäus U; Moussa, Amgad S; Soos, Miroslav; Morbidelli, Massimo

    2010-08-17

    Aggregation of rigid colloidal particles leads to fractal-like structures that are characterized by a fractal dimension d(f) which is a key parameter for describing aggregation processes. This is particularly true in shear aggregation where d(f) strongly influences aggregation kinetics. Direct measurement of d(f) in the early stages of shear aggregation is however difficult, as the aggregates are small and few in number. An alternative method for determining d(f) is to use an aggregation model that when fitted to the time evolution of the cluster mass distribution allows for estimating d(f). Here, we explore three such models, two of which are based on an effective collision sphere and one which directly incorporates the permeable structure of the aggregates, and we apply them for interpreting the initial aggregate growth measured experimentally in a turbulent stirred tank reactor. For the latter, three polystyrene latexes were used that differed only in the size of the primary particles (d(p) = 420, 600, and 810 nm). It was found that all three models describe initial aggregation kinetics reasonably well using, however, substantially different values for d(f). To discriminate among the models, we therefore also studied the regrowth of preformed aggregates where d(f) was experimentally accessible. It was found that only the model that directly incorporates the permeable structure of the aggregates is able to predict correctly this second type of experiments. Applying this model to the initial aggregation kinetics, we conclude that the actual initial fractal dimension is d(f) = 2.07 +/- 0.04 as found from this model.

  13. Blue-emitting pyrene-based aggregates.

    Science.gov (United States)

    Valera, Jorge S; Calbo, Joaquín; Gómez, Rafael; Ortí, Enrique; Sánchez, Luis

    2015-06-25

    The supramolecular polymerization of pyrene imidazoles 1 and 2, governed by H-bonding and C-H···π interactions, yields aggregates showing the characteristic bluish emission pattern of pyrene-based monomers.

  14. A Survey of Distributed Data Aggregation Algorithms

    CERN Document Server

    Jesus, Paulo; Almeida, Paulo Sérgio

    2011-01-01

    Distributed data aggregation is an important task, allowing the decentralized determination of meaningful global properties, that can then be used to direct the execution of other applications. The resulting values result from the distributed computation of functions like COUNT, SUM and AVERAGE. Some application examples can found to determine the network size, total storage capacity, average load, majorities and many others. In the last decade, many different approaches have been proposed, with different trade-offs in terms of accuracy, reliability, message and time complexity. Due to the considerable amount and variety of aggregation algorithms, it can be difficult and time consuming to determine which techniques will be more appropriate to use in specific settings, justifying the existence of a survey to aid in this task. This work reviews the state of the art on distributed data aggregation algorithms, providing three main contributions. First, it formally defines the concept of aggregation, characterizin...

  15. 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 ...

  16. Nanoscale Ionic Aggregate Morphology in Zwitterionic Copolymers

    Science.gov (United States)

    Choi, Jae-Hong; Huyck, Rebecca; Salas-de La Cruz, David; Long, Timothy E.; Winey, Karen I.

    2009-03-01

    The morphology of two different zwitterionic copolymers, poly(sulfobetaine methacrylate-ran-butyl acrylate), and poly(sulfobetaine methacrylamide-ran-butyl acrylate) are investigated as a function of the mol % content of SBMA (7 and 9 mol %) and SBMAm (6, 10 and 13 mol %), respectively. In both copolymers, X-ray scattering results show a new structure in the material arising from ionic aggregates. The sizes of the ionic aggregates are obtained through the scattering model. The sizes of the ionic aggregates increase as the ion content increases. The application of scanning transmission electron microscopy to the study of ionomer morphology has enabled direct, model-independent visualization of the ionic aggregates. The correlation between X-ray scattering results and the real space imaging for morphology of these zwitterionic copolymers will be presented.

  17. 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...

  18. 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.

  19. Familial aggregation and childhood blood pressure.

    Science.gov (United States)

    Wang, Xiaoling; Xu, Xiaojing; Su, Shaoyong; Snieder, Harold

    2015-01-01

    There is growing concern about elevated blood pressure (BP) in children. The evidence for familial aggregation of childhood BP is substantial. Twin studies have shown that a large part of the familial aggregation of childhood BP is due to genes. The first part of this review provides the latest progress in gene finding for childhood BP, focusing on the combined effects of multiple loci identified from the genome-wide association studies on adult BP. We further review the evidence on the contribution of the genetic components of other family risk factors to the familial aggregation of childhood BP including obesity, birth weight, sleep quality, sodium intake, parental smoking, and socioeconomic status. At the end, we emphasize the promise of using genomic-relatedness-matrix restricted maximum likelihood (GREML) analysis, a method that uses genome-wide data from unrelated individuals, in answering a number of unsolved questions in the familial aggregation of childhood BP.

  20. Control of aggregation-induced emission by DNA hybridization

    OpenAIRE

    Li, Shaoguang; Langenegger, Simon Matthias; Häner, Robert

    2013-01-01

    Aggregation-induced emission (AIE) was studied by hybridization of dialkynyl-tetraphenylethylene (DATPE) modified DNA strands. Molecular aggregation and fluorescence of DATPEs are controlled by duplex formation.

  1. 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

  2. Low aggregation state diminishes ferrihydrite reactivity

    Science.gov (United States)

    Braunschweig, Juliane; Heister, Katja; Meckenstock, Rainer U.

    2013-04-01

    Ferrihydrite is an abundant iron(oxy)hydroxide in soils and sediments and plays an important role in microbial iron cycling due to its high reactivity. Therefore, it is often synthesized and used in geomicrobiological and mineralogical studies. The reactivities of synthetic ferrihydrites vary between different studies and synthesis protocols. Hence, we synthesized five different ferrihydrites and characterized them with XRD, FTIR, XPS, and BET specific surface area. The reactivity of the ferrihydrite samples towards ascorbic acid was examined and compared with microbial reduction rates by Geobacter sulfurreducens. FTIR and XRD results show the presence of secondary, higher crystalline iron oxide phases like goethite and akaganeite for two samples. Consequently, those samples revealed lower biotic and abiotic reduction rates compared to pure ferrihydrite. Comparison of reduction rates with the specific surface area of all ferrihydrites showed neither correlation with abiotic reductive dissolution nor with microbial reduction. Especially one sample, characterized by a very low aggregation state and presence of secondary minerals, revealed a poor reactivity. We speculate that apart from the occurring secondary minerals also the low aggregation state played an important role. Decreasing aggregation diminishes the amount of kinks and edges on the surfaces, which are produced at contact sites in aggregates. According to dissolution theories, dissolution mainly starts at those surface defects and slows down with decreasing amount of defects. Furthermore, the non-aggregated ferrihydrite is free of micropores, a further stimulant for dissolution. Independent repetitions of experiments and syntheses according to the same protocol but without formation of secondary minerals, confirmed the low reactivity of the non-aggregated ferrihydrite. In summary, our results indicate that a decreasing aggregation state of ferrihydrite to a certain size does increase the reactivity

  3. 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.

  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.

    2017-01-01

    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. PMID:28255164

  5. Influence of Phenylalanine on Carotenoid Aggregation

    Science.gov (United States)

    Lu, L.; Ni, X.; Luo, X.

    2015-01-01

    The carotenoids lutein and β-carotene form, in 1:1 ethanol-water mixtures H-aggregates, of different strengths. The effects of phenylalanine on these aggregates were recorded by UV-Vis absorption, steady-state fluorescence, and Raman spectra. The H-aggregate of lutein was characterized by a large 78 nm blue shift in the absorption spectra, confirming the strong coupling between hydroxyl groups of adjacent molecules. The 15 nm blue shift in the β-carotene mixture also indicates that it was assembled by weak coupling between polyenes. After adding phenylalanine, the reducing absorption strength of the aggregates of lutein and reappearance of vibrational substructure indicate that the hydroxyl and amino groups of phenylalanine may coordinate to lutein and disaggregate the H-aggregates. However, phenylalanine had no effect on aggregates of β-carotene. The Raman spectra show three bands of carotenoids whose intensities decreased with increasing phenylalanine concentration. The frequency of ν1 corresponding to the length of the conjugated region was more sensitive to the solution of lutein. This coordination of phenylalanine to lutein could increase the length of the conjugated region. In addition, phenylalanine significantly affected the excited electronic states of carotenoids, which were crucial in the energy transfer from carotenoids to chlorophyll a in vivo.

  6. Growth hormone aggregates in the rat adenohypophysis

    Science.gov (United States)

    Farrington, M.; Hymer, W. C.

    1990-01-01

    Although it has been known for some time that GH aggregates are contained within the rat anterior pituitary gland, the role that they might play in pituitary function is unknown. The present study examines this issue using the technique of Western blotting, which permitted visualization of 11 GH variants with apparent mol wt ranging from 14-88K. Electroelution of the higher mol wt variants from gels followed by their chemical reduction with beta-mercaptoethanol increased GH immunoassayability by about 5-fold. With the blot procedure we found 1) that GH aggregates greater than 44K were associated with a 40,000 x g sedimentable fraction; 2) that GH aggregates were not present in glands from thyroidectomized rats, but were in glands from the thyroidectomized rats injected with T4; 3) that GH aggregates were uniquely associated with a heavily granulated somatotroph subpopulation isolated by density gradient centrifugation; and 4) that high mol wt GH forms were released from the dense somatotrophs in culture, since treatment of the culture medium with beta-mercaptoethanol increased GH immunoassayability by about 5-fold. Taken together, the results show that high mol wt GH aggregates are contained in secretory granules of certain somatotrophs and are also released in aggregate form from these cells in vitro.

  7. Aggregation kinetics of coalescing polymer colloids.

    Science.gov (United States)

    Gauer, Cornelius; Jia, Zichen; Wu, Hua; Morbidelli, Massimo

    2009-09-01

    The aggregation behavior of a soft, rubbery colloidal system with a relatively low glass transition temperature, T(g) approximately -20 degrees C, has been investigated. It is found that the average gyration and hydrodynamic radii, R(g) and R(h), measured by light scattering techniques, evolve in time in parallel, without exhibiting the crossover typical of rigid particle aggregation. Cryogenic scanning electron microscopy (cryo-SEM) images reveal sphere-like clusters, indicating that complete coalescence between particles occurs during aggregation. Since coalescence leads to a reduction in the total colloidal surface area, the surfactant adsorption equilibrium, and thus the colloidal stability, change in the course of aggregation. It is found that to simulate the observed kinetic behavior based on the population balance equations, it is necessary to assume that all the clusters are spherical and to account for variations in the colloidal stability of each aggregating particle pair with time. This indicates that, for the given system, the coalescence is very fast, i.e., its time scale is much smaller than that of the aggregation.

  8. An Identity Based Aggregate Signature from Pairings

    Directory of Open Access Journals (Sweden)

    Yike Yu

    2011-04-01

    Full Text Available An aggregate signature is a useful digital signature that supports aggregation: Given n signatures on n distinct messages from n distinct users, aggregate signature scheme is possible to aggregate all these signature into a single short signature. This single signature, along with the n original messages will convince any verifier that the n users did indeed sign the n original messages respectively (i.e., for i=1,...,n user i signed message  mi. In this paper, we propose an identity based aggregate signature scheme which requires constant pairing operations in the verification and the size of aggregate signature is independent of the number of signers. We prove that the proposed signature scheme is secure against existential forgery under adaptively chosen message and identity attack in the random oracle model assuming the intractability of the computational Diffie-Hellman problem.

  9. Aggregation of Dodecyl 1-Pyrenylmethyl Ether and Its Application in Structure-Polarity Relations of Aggregates

    Institute of Scientific and Technical Information of China (English)

    SANG,Da-Yong; TIAN,Juan; JI,Guo-Zhen

    2006-01-01

    The aggregation behavior of dodecyl 1-pyrenylmethyl ether was studied in dioxane-water mixture solvents by fluorescence techniques. The labeled pyrenyl group was effective in monitoring the polarity change of its environment during aggregation processes. Based on the structural effects such as chain-length effect, self-coiling effect,and branch-group effect on the polarity of the probe environment, the structure features of aggregates were discussed and have been used to interpret the effect of the structural features on the aggregates formed by three cholesteryl esters and three long chain alkanes.

  10. 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

  11. 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.

  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. Hydration mechanism and leaching behavior of bauxite-calcination-method red mud-coal gangue based cementitious materials.

    Science.gov (United States)

    Zhang, Na; Li, Hongxu; Liu, Xiaoming

    2016-08-15

    A deep investigation on the hydration mechanism of bauxite-calcination-method red mud-coal gangue based cementitious materials was conducted from viewpoints of hydration products and hydration heat analysis. As a main hydration product, the microstructure of C-A-S-H gel was observed using high resolution transmission electron microscopy. It was found that the C-A-S-H gel is composed of amorphous regions and nanocrystalline regions. Most of regions in the C-A-S-H gel are amorphous with continuous distribution, and the nanocrystalline regions on scale of ∼5nm are dispersed irregularly within the amorphous regions. The hydration heat of red mud-coal gangue based cementitious materials is much lower than that of the ordinary Portland cement. A hydration model was proposed for this kind of cementitious materials, and the hydration process mainly consists of four stages which are dissolution of materials, formation of C-A-S-H gels and ettringite, cementation of hydration products, and polycondensation of C-A-S-H gels. There are no strict boundaries among these four basic stages, and they proceed crossing each other. Moreover, the leaching toxicity tests were also performed to prove that the developed red mud-coal gangue based cementitious materials are environmentally acceptable.

  14. Regulated protein aggregation: stress granules and neurodegeneration

    Directory of Open Access Journals (Sweden)

    Wolozin Benjamin

    2012-11-01

    Full Text Available Abstract The protein aggregation that occurs in neurodegenerative diseases is classically thought to occur as an undesirable, nonfunctional byproduct of protein misfolding. This model contrasts with the biology of RNA binding proteins, many of which are linked to neurodegenerative diseases. RNA binding proteins use protein aggregation as part of a normal regulated, physiological mechanism controlling protein synthesis. The process of regulated protein aggregation is most evident in formation of stress granules. Stress granules assemble when RNA binding proteins aggregate through their glycine rich domains. Stress granules function to sequester, silence and/or degrade RNA transcripts as part of a mechanism that adapts patterns of local RNA translation to facilitate the stress response. Aggregation of RNA binding proteins is reversible and is tightly regulated through pathways, such as phosphorylation of elongation initiation factor 2α. Microtubule associated protein tau also appears to regulate stress granule formation. Conversely, stress granule formation stimulates pathological changes associated with tau. In this review, I propose that the aggregation of many pathological, intracellular proteins, including TDP-43, FUS or tau, proceeds through the stress granule pathway. Mutations in genes coding for stress granule associated proteins or prolonged physiological stress, lead to enhanced stress granule formation, which accelerates the pathophysiology of protein aggregation in neurodegenerative diseases. Over-active stress granule formation could act to sequester functional RNA binding proteins and/or interfere with mRNA transport and translation, each of which might potentiate neurodegeneration. The reversibility of the stress granule pathway also offers novel opportunities to stimulate endogenous biochemical pathways to disaggregate these pathological stress granules, and perhaps delay the progression of disease.

  15. A Novel Method to Quantify Soil Aggregate Stability by Measuring Aggregate Bond Energies

    Science.gov (United States)

    Efrat, Rachel; Rawlins, Barry G.; Quinton, John N.; Watts, Chris W.; Whitmore, Andy P.

    2016-04-01

    Soil aggregate stability is a key indicator of soil quality because it controls physical, biological and chemical functions important in cultivated soils. Micro-aggregates are responsible for the long term sequestration of carbon in soil, therefore determine soils role in the carbon cycle. It is thus vital that techniques to measure aggregate stability are accurate, consistent and reliable, in order to appropriately manage and monitor soil quality, and to develop our understanding and estimates of soil as a carbon store to appropriately incorporate in carbon cycle models. Practices used to assess the stability of aggregates vary in sample preparation, operational technique and unit of results. They use proxies and lack quantification. Conflicting results are therefore drawn between projects that do not provide methodological or resultant comparability. Typical modern stability tests suspend aggregates in water and monitor fragmentation upon exposure to an un-quantified amount of ultrasonic energy, utilising a laser granulometer to measure the change in mean weight diameter. In this project a novel approach has been developed based on that of Zhu et al., (2009), to accurately quantify the stability of aggregates by specifically measuring their bond energies. The bond energies are measured operating a combination of calorimetry and a high powered ultrasonic probe, with computable output function. Temperature change during sonication is monitored by an array of probes which enables calculation of the energy spent heating the system (Ph). Our novel technique suspends aggregates in heavy liquid lithium heteropolytungstate, as opposed to water, to avoid exposing aggregates to an immeasurable disruptive energy source, due to cavitation, collisions and clay swelling. Mean weight diameter is measured by a laser granulometer to monitor aggregate breakdown after successive periods of calculated ultrasonic energy input (Pi), until complete dispersion is achieved and bond

  16. Effects of calcination and reduction temperature on the performance of Co-Pt-ZrO2/γ-A12O3 catalysts for Fischer-Tropsch synthesis%焙烧及还原温度对Co-Pt-ZrO2/γ-Al2O3催化剂费托合成反应性能的影响

    Institute of Scientific and Technical Information of China (English)

    孙燕; 孙启文; 蒋凡凯; 刘继森; 张宗森

    2012-01-01

    Co-Pt-ZrO2/γ-Al2 O, catalysts were prepared by using impregnation method and characterized by BET, XRD and TPR techniques; the effects of calcination and reduction temperature on their catalytic performance for Fischer-Tropsch synthesis (FTS) were investigated in a slurry-phase continuously stirred tank reactor (CSTR). The results showed that the catalysts calcined at high temperature exhibits low activity and selectivity to heavy hydrocarbons, since high temperature calcination may lead a strong interaction between cobalt species and -γ-Al2O3 support, the formation of less reducible cobalt aluminate species, and aggregation of cobalt oxide crystals. Cobalt oxides cannot be reduced completely at a low temperature, while the aggregation or sintering of the active species may be prominent by carrying out the reduction at extra-high temperature; all these can deteriorate the catalytic performance of Co-Pt-ZrO2/γ-Al2O3. Under 483 K, 2.4 Mpa, a H2/CO molar ratio of 2.0, and a space velocity of 3.6 L/(gcat-h), the catalyst 31.08%Co-0. Ll%Pt-7.16%ZrO2/Al2O3 calcined at 673 K and reduced in hydrogen at 653 K exhibits high catalytic performance for FTS; the conversion of CO and selectivity to C5+ reach 27.0% and 83.0% , respectively.%采用浸渍法制备了Co-Pt-ZrO2/γ-Al2O3催化剂,对其进行了BET、XRD和TPR等表征,并在浆态床反应器上考察了焙烧温度和还原温度对催化剂费托合成反应性能的影响.结果表明,焙烧温度过高,容易造成Co物种和载体间的相互作用增强,使部分氧化钻颗粒聚集或烧结,导致催化剂的F-T合成反应活性和C5+烃选择性降低.还原温度较低时,钴物种不能充分还原,CO加氢活性低,甲烷选择性高,重质烃选择性低;还原温度过高,则可能造成活性物种的烧结,反而降低了催化剂的活性和重质烃选择性.在原料气n(H2)/n( CO)=2.0、483 K、2.4 MPa和空速3.6 L/( gcat·h)的条件下,31.08% Co~0.11%Pt ~ 7.16% ZrO2/Al2O3

  17. Spatial Prediction of Soil Aggregate Stability and Aggregate-Associated Organic Carbon Content at the Catchment Scale Using Geostatistical Techniques

    Institute of Scientific and Technical Information of China (English)

    J.MOHAMMADI; M.H.MOTAGHIAN

    2011-01-01

    The association of organic carbon with secondary parzicles (aggregates) results in its storage and retention in soil. A study was carried out at a catchment covering about 92 km2 to predict spatial variability of soil water-stable aggregates (WSA), mean weight diameter (MWD) of aggregates and organic carbon (OC) content in macro- (> 2 mm), meso- (1-2 mm), and micro-aggregate (< 1 mm) fractions, using geostatistical methods. One hundred and eleven soil samples were c(o)llected at the 0-10 cm depth and fractionated into macro-, meso-, and micro-aggregates by wet sieving. The OC content was determined for each fraction. A greater percentage of water-stable aggregates was found for micro-aggregates, followed by meso-aggregates. Aggregate OC content was greatest in meso-aggregates (9 g kg-1), followed by micro-aggregates (7 g kg-1), while the least OC content was found in macro-aggregates (3 g kg-1). Although a significart effect (P = 0.000) of aggregate size on aggregate OC content was found, however, our findings did not support the model of aggregate hierarchy.Land use had a significant effect (P = 0.073) on aggregate OC content. The coefficients of variation (CVs) for OC contents associated with each aggregate fraction indicated macro-aggregates as the most variable (CV = 71%). Among the aggregate fractions, the micro-aggregate fraction had a lower CV value of 27%. The mean content of WSA ranged from 15% for macro-aggregates to 84% for micro-aggregates. Geostatistical analysis showed that the measured soil variables exhibited differences in their spatial patterns in both magnitude and space at each aggregate size fraction. The relative nugget variance for most aggregate-associated properties was lower than 45%. The range value for the variogram of water-stable aggregates was almost similar (about 3 km) for the three studied aggregate size classes. The range value for the variogram of aggregate-associated OC contents ranged from about 3 km for macro-aggregates

  18. 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.

  19. Preparation and application of acidified/calcined red mud catalyst for catalytic degradation of butyl xanthate in Fenton-like process.

    Science.gov (United States)

    Shao, Luhua; Wei, Guangtao; Wang, Yizhi; Li, Zhongmin; Zhang, Linye; Zhao, Shukai; Zhou, Ming

    2016-08-01

    Acidified/calcined red mud (ACRM), a novel catalyst used in Fenton-like process, was prepared by acidification and calcination of red mud (RM). Catalyst characterization showed that iron phase of ACRM was mainly α-Fe2O3 and ACRM was a porous material with rough surface and loose structure. Degradation of butyl xanthate in Fenton-like process catalyzed by ACRM was investigated. Butyl xanthate was effectively degraded, and the degradation of butyl xanthate was well fitted by second order kinetic model. ACRM had an excellent long-term stability in a Fenton-like process. The possible mechanisms of hydroxyl radical production and butyl xanthate degradation in a Fenton-like process catalyzed by ACRM were presented.

  20. 全氟物改性煅白的防吸湿机理%Anti-moisture mechanism of calcined dolomite modified by perfluoroalkylethyl acrylate

    Institute of Scientific and Technical Information of China (English)

    梁晓波; 李明照; 王国卫; 梁一然; 张耀斌; 毛嘉; 任川兮

    2015-01-01

    对煅白表面锚固偶氮二氰基戊酸引发全氟烷基乙基丙烯酸酯(FM)聚合而制备的防吸湿煅白进行研究,利用 XPS、IR、DSC、TG、SEM 物理吸收和接触角测量等方法对改性前后煅白的结构、比表面积、形貌和疏水接触角等进行表征,并分析改性后煅白吸湿性降低的原因和机理。结果表明:煅白表面发生了偶联、锚固及聚合反应。锚固引发剂的煅白引发FM原位分散聚合而制得防吸湿煅白,其吸湿率随FM质量分数的增加而降低,当FM质量分数达到7%时,吸湿率不再下降,改性后煅白1 h的吸湿率由1.39%下降到0.017%;聚全氟烷基乙基丙烯酸酯(PFM)的接枝率为0.5%、接枝效率为26.6%,煅白表面出现一层连续而完整的全氟聚合物膜,其厚度约为8 nm。%4,4'-Azobis(4-cyanovaleric acid) (ACPA) was anchored onto the surface of calcined dolomite and radical graft polymerization of perfluoroalkylethyl acrylate (FM) from the modified calcined dolomite through dispersion polymerization were investigated. The structure, specific surface area, morphology and hydrophobic contact angle of calcined dolomite surface were characterised by XPS, IR, DSC, TG, SEM, physical absorption and contact angle measurement, and the reason and mechanism on the decreasing the moisture absorption rate of calcined dolomite after the modification were studied. The results show that the coupling, anchoring and polymerization reactions happen on the surface of calcined dolomite. Poly (Perfluoroalkylethyl acrylate) (PFM) is effectively grafted onto calcined dolomite through the initiation of anchored ACPA during in-situ dispersion polymerization. It shows that the moisture absorption rate of calcined dolomite decreases with increasing of the mass fraction of FM. When the mass fraction of FM is 7%, The moisture absorption rate decreases from 1.39% to 0.017% after modification for 1 h. The grafting rate and efficiency of PFA are 0.5% and

  1. 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.

  2. 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

  3. Structure and aggregation in model tetramethylurea solutions

    Energy Technology Data Exchange (ETDEWEB)

    Gupta, Rini; Patey, G. N., E-mail: patey@chem.ubc.ca [Department of Chemistry, University of British Columbia, Vancouver, British Columbia V6T 1Z1 (Canada)

    2014-08-14

    The structure of model aqueous tetramethylurea (TMU) solutions is investigated employing large-scale (32 000, 64 000 particles) molecular dynamics simulations. Results are reported for TMU mole fractions, X{sub t}, ranging from infinite dilution up to 0.07, and for two temperatures, 300 and 330 K. Two existing force fields for TMU-water solutions are considered. These are the GROMOS 53A6 united-atom TMU model combined with SPC/E water [TMU(GROMOS-UA)/W(SPC/E)], and the more frequently employed AMBER03 all-atom force field for TMU combined with the TIP3P water model [TMU(AMBER-AA)/W(TIP3P)]. It is shown that TMU has a tendency towards aggregation for both models considered, but the tendency is significantly stronger for the [TMU(AMBER-AA)/W(TIP3P)] force field. For this model signs of aggregation are detected at X{sub t} = 0.005, aggregation is a well established feature of the solution at X{sub t} = 0.02, and the aggregates increase further in size with increasing concentration. This is in agreement with at least some experimental studies, which report signals of aggregation in the low concentration regime. The TMU aggregates exhibit little structure and are simply loosely ordered, TMU-rich regions of solution. The [TMU(GROMOS-UA)/W(SPC/E)] model shows strong signs of aggregation only at higher concentrations (X{sub t} ≳ 0.04), and the aggregates appear more loosely ordered, and less well-defined than those occurring in the [TMU(AMBER-AA)/W(TIP3P)] system. For both models, TMU aggregation increases when the temperature is increased from 300 to 330 K, consistent with an underlying entropy driven, hydrophobic interaction mechanism. At X{sub t} = 0.07, the extra-molecular correlation length expected for microheterogeneous solutions has become comparable with the size of the simulation cell for both models considered, indicating that even the systems simulated here are sufficiently large only at low concentrations.

  4. Aggregate Particles in the Plumes of Enceladus

    CERN Document Server

    Gao, Peter; Zhang, Xi; Ingersoll, Andrew P

    2015-01-01

    Estimates of the total particulate mass of the plumes of Enceladus are important to constrain theories of particle formation and transport at the surface and interior of the satellite. We revisit the calculations of Ingersoll and Ewald (2011), who estimated the particulate mass of the Enceladus plumes from strongly forward scattered light in Cassini ISS images. We model the plume as a combination of spherical particles and irregular aggregates resulting from the coagulation of spherical monomers, the latter of which allows for plumes of lower particulate mass. Though a continuum of solutions are permitted by the model, the best fits to the ISS data consist either of low mass plumes composed entirely of small aggregates or high mass plumes composed of large aggregates and spheres. The high mass plumes can be divided into a population of large aggregates with total particulate mass of 116 +/- 12 X 10^3 kg, and a mixed population of spheres and aggregates consisting of a few large monomers that has a total plume...

  5. 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.

  6. 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.

  7. Preparation of nanosized barium zirconate powder by thermal decomposition of urea in an aqueous solution containing barium and zirconium, and by calcination of the precipitate

    OpenAIRE

    Boschini, Frédéric; Robertz, B.; Rulmont, André; Cloots, Rudi

    2003-01-01

    The synthesis of barium zirconate was initiated by urea induced homogeneous precipitation followed by a "low temperature" thermal treatment. The kinetic of the reaction and the optimum urea/cation ratio have been determined by means of X-ray diffraction and Inductive Coupled Plasma analyses. It has been demonstrated that an amorphous zirconium hydrated oxide starts to precipitate followed by the precipitation of barium carbonate. A calcination at 1200 degreesC during 2 h gives rise to the for...

  8. 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.

  9. Aggregation Pheromone System: A Real-parameter Optimization Algorithm using Aggregation Pheromones as the Base Metaphor

    Science.gov (United States)

    Tsutsui, Shigeyosi

    This paper proposes an aggregation pheromone system (APS) for solving real-parameter optimization problems using the collective behavior of individuals which communicate using aggregation pheromones. APS was tested on several test functions used in evolutionary computation. The results showed APS could solve real-parameter optimization problems fairly well. The sensitivity analysis of control parameters of APS is also studied.

  10. 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)

  11. Web Data Aggregation in MOLAP: Approach, Language, and Implementation

    Institute of Scientific and Technical Information of China (English)

    ZHU Yan; TANG Hui-jia; MA Yong-qiang

    2007-01-01

    This paper investigates the Web data aggregation issues in multidimensional on-line analytical processing (MOLAP) and presents a rule-driven aggregation approach. The core of the approach is defining aggregate rules. To define the rules for reading warehouse data and computing aggregates, a rule definition language - array aggregation language (AAL) is developed. This language treats an array as a function from indexes to values and provides syntax and semantics based on monads. External functions can be called in aggregation rules to specify array reading, writing, and aggregating. Based on the features of AAL, array operations are unified as function operations, which can be easily expressed and automatically evaluated. To implement the aggregation approach, a processor for computing aggregates over the base cube and for materializing them in the data warehouse is built, and the component structure and working principle of the aggregation processor are introduced.

  12. Cellular strategies for regulating functional and nonfunctional protein aggregation.

    Science.gov (United States)

    Gsponer, Jörg; Babu, M Madan

    2012-11-29

    Growing evidence suggests that aggregation-prone proteins are both harmful and functional for a cell. How do cellular systems balance the detrimental and beneficial effect of protein aggregation? We reveal that aggregation-prone proteins are subject to differential transcriptional, translational, and degradation control compared to nonaggregation-prone proteins, which leads to their decreased synthesis, low abundance, and high turnover. Genetic modulators that enhance the aggregation phenotype are enriched in genes that influence expression homeostasis. Moreover, genes encoding aggregation-prone proteins are more likely to be harmful when overexpressed. The trends are evolutionarily conserved and suggest a strategy whereby cellular mechanisms specifically modulate the availability of aggregation-prone proteins to (1) keep concentrations below the critical ones required for aggregation and (2) shift the equilibrium between the monomeric and oligomeric/aggregate form, as explained by Le Chatelier's principle. This strategy may prevent formation of undesirable aggregates and keep functional assemblies/aggregates under control.

  13. Effect of calcination temperature on the photocatalytic activity of TiO2 powders prepared by co-precipitation of TiCl3

    Science.gov (United States)

    Yudoyono, Gatut; Ichzan, Nur; Zharvan, Vicran; Daniyati, Rizqa; Santoso, Hadi; Indarto, Bachtera; Pramono, Yono Hadi; Zainuri, Mochamad; Darminto

    2016-04-01

    The adsorption of basic dye methylene blue (MB) onto titanium dioxide (titania) powder that were prepared by coprecipitation method of TiCl3 and NH4OH as iniatial material with different calcination temperature was studied to examine the photocatalytic activity. Synthesis process carried out by the solution pH was adjusted to be 8. Effect of calcination temperature on the titania powder were characterized with Differential Scanning Calorimetry/Thermogravimetry (DSC/TG), X-ray diffraction (XRD), and Scanning Electron Microscopy (SEM). The result of TG and XRD showed that the NH4Cl decomposed between 235-372°C. The XRD result showed that the anatase TiO2 only contained a single phase when the calcination temperature of the precursor at 800°C, and over which it began to grow rutile phase. The influence of synthesis condition on the photocatalytic activity of TiO2 powder was determined by the photodegradation of MB dye under UV light.

  14. The influence of coating solution and calcination condition on the durability of Ir1-xSnxO2/Ti anodes for oxygen evolution

    Science.gov (United States)

    Kato, Zenta; Kashima, Ryo; Tatsumi, Kohei; Fukuyama, Shinnosuke; Izumiya, Koichi; Kumagai, Naokazu; Hashimoto, Koji

    2016-12-01

    For oxygen formation without forming chlorine in seawater electrolysis for hydrogen production we have been using the anode consisting of three layers of MnO2-type multiple oxide catalyst, intermediate layer and titanium substrate. The intermediate layer was used for prevention of oxidation of the titanium substrate during anodic polarization for oxygen evolution and was prepared by calcination of butanol solutions of H2IrCl6 and SnCl4 coated on titanium. The protectiveness of Ir1-xSnxO2 layer formed was directly examined using Ir1-xSnxO2/Ti anodes in H2SO4 solution changing the preparation conditions of the layer. When the sum of Ir4+ and Sn4+ was 0.1 M, the highest protectiveness was observed at 0.06 M Sn4+. Although an increase in calcination temperature led to the formation of Ir1-x-ySnxTiyO2 triple oxide with a slightly lower catalytic activity for oxygen evolution, the anode calcined at 450 °C showed the highest protectiveness.

  15. Effect of calcination temperature on structural properties and catalytic activity in oxidation reactions of LaNiO3 perovskite prepared by Pechini method

    Institute of Scientific and Technical Information of China (English)

    K.Rida; M.A.Pe(n)a; E.Sastre; A.Martínez-Arias

    2012-01-01

    The study presented the preparation of the perovskite oxide LaNiO3 by the complex citrate method,paying particular attention to evolution of its formation from the amorphous precursor with varied calcination temperatures.The products obtained after heat treatment under air between 200 and 800 ℃ were characterized by X-ray diffraction (XRD),thermogravimetric and differential thermal analysis (TG-DTA),Fourier transform infrared spectroscopy (FTIR),SBET measurements and X-ray photoelectron spectroscopy (XPS).The results showed the formation of a single phase with perovskite structure from ca.550 ℃.Tests on the two catalytic oxidation reactions of C3H6 and CO over the system calcined between mentioned temperatures were examined on the basis of characterization results and showed that optimum catalytic properties for such reactions were achieved for the perovskite calcined at 600 ℃.In turn,correlations between redox and catalytic properties were established on the basis of thermogravimetric temperature programmed reduction (TPR) analysis.

  16. Effect of Calcination Temperature on Surface Morphology and Photocatalytic Activity in TiO2 Thin Film Prepared by Spin Coating Technique

    Directory of Open Access Journals (Sweden)

    Krishna Mohan Mothi

    2014-10-01

    Full Text Available TiO2 thin films were deposited on glass substrate using Sol-Gel derived precursor by Spin Coating technique at different calcination temperatures. Structural identity of the prepared films was con- firmed by powder X-ray diffraction measurements. Morphology of the films was monitored using Atomic force microscopy and it was observed that calcination temperature of 400 °C favored TiO2 nano- fibers. Photocatalytic activity of the films was checked by observing the degradation of herbicide Atrazine in UV region and the percentage of degradation was analyzed by HPLC method. © 2014 BCREC UNDIP. All rights reservedReceived: 21st November 2013; Revised: 18th March 2014; Accepted: 29th June 2014How to Cite: Mothi, K.M., Soumya, G., Sugunan, S. (2014. Effect of Calcination Temperature on Surface Morphology and Photocatalytic Activity in TiO2 Thin Films Prepared by Spin Coating Technique. Bulletin of Chemical Reaction Engineering & Catalysis, 9 (3: 175-181. (doi:10.9767/bcrec.9.3.5733.175-181Permalink/DOI: http://dx.doi.org/10.9767/bcrec.9.3.5733.175-181

  17. 磷石膏制备复相磷石膏煅烧工艺研究%Research on calcining process of duplex gypsum using phosphogypsum

    Institute of Scientific and Technical Information of China (English)

    孙清臣; 杨敏

    2013-01-01

    The calcining process of duplex gypsum using phosphogypsum was studied.the results show that holding time and heating rate have an greater influence on the ratio of hemihydrate and anhydrite after phosphogypsum calcination,so dulex phosphogypsum with different ratio of hemihydrate and anhydrite can be prepared by controling holding time and heating rate during phosphogypsum calcination.compare with one-phase gypsum,duplex phosphogypsum possess better early strength and late strength.%  对磷石膏制备的复相石膏煅烧工艺进行了研究。结果表明:保温时间和升温速率对两种石膏的烧成比例影响较大。获得不同半水-无水比例的复相磷石膏体系可以通过控制升温速率和保温时间来实现。复相磷石膏与单相石膏比较,具有较好的早期强度和后期强度。

  18. 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.

  19. An ROLAP Aggregation Algorithm with the Rules Being Specified

    Science.gov (United States)

    Zhengqiu, Weng; Tai, Kuang; Lina, Zhang

    This paper introduces the base theory of data warehouse and ROLAP, and presents a new kind of ROLAP aggregation algorithm, which has calculation algorithms. It covers the shortage of low accuracy of traditional aggregation algorithm that aggregates only by addition. The ROLAP aggregation with calculation algorithm which can aggregate according to business rules improves accuracy. And key designs and procedures are presented. Compared with the traditional method, its efficiency is displayed in an experiment.

  20. The Nation's top 25 construction aggregates producers

    Science.gov (United States)

    Willett, Jason Christopher

    2013-01-01

    U.S. production of construction aggregates in 2011 was 2.17 billion short tons, valued at $17.2 billion, free on board (f.o.b.) at plant. Construction aggregates production decreased by 37 percent, and the associated value decreased by 25 percent, compared with the record highs reported in 2006. In 2011, construction aggregates production increased for the first time since 2006, owing to a very slight increase in the production of both construction sand and gravel and crushed stone. The average unit value, which is the f.o.b. at plant price of a ton of material, increased slightly, but is still less than the average unit value of two years prior.

  1. Aggregate ranking of the world's leading universities

    Directory of Open Access Journals (Sweden)

    Vladimir M. Moskovkin

    2015-06-01

    Full Text Available The paper presents a methodology for calculating the aggregate global university ranking (Aggregated Global University Ranking, or AGUR, which consists of an automated presentation of the comparable lists of names for different universities from particular global university rankings (using Machine Learning and Mining Data algorithms and a simple procedure of aggregating particular global university rankings (summing up the university ranking positions from different particular rankings and their subsequent ranking. The second procedure makes it possible to bring lists of universities from particular rankings, which are nonidentical by length, to one size. The paper includes a sample AGUR for six particular global university rankings as of 2013, as well as cross-correlation matrices and intersection matrices for AGUR for 2011-2013, all created by means of using the Python-based software.

  2. 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.

  3. Linguistic Weighted Aggregation under Confidence Levels

    Directory of Open Access Journals (Sweden)

    Chonghui Zhang

    2015-01-01

    Full Text Available We develop some new linguistic aggregation operators based on confidence levels. Firstly, we introduce the confidence linguistic weighted averaging (CLWA operator and the confidence linguistic ordered weighted averaging (CLOWA operator. These two new linguistic aggregation operators are able to consider the confidence level of the aggregated arguments provided by the information providers. We also study some of their properties. Then, based on the generalized means, we introduce the confidence generalized linguistic ordered weighted averaging (CGLOWA operator. The main advantage of the CGLOWA operator is that it includes a wide range of special cases such as the CLOWA operator, the confidence linguistic ordered weighted quadratic averaging (CLOWQA operator, and the confidence linguistic ordered weighted geometric (CLOWG operator. Finally, we develop an application of the new approach in a multicriteria decision-making under linguistic environment and illustrate it with a numerical example.

  4. Multi-Dimensional Aggregation for Temporal Data

    DEFF Research Database (Denmark)

    Böhlen, M. H.; Gamper, J.; Jensen, Christian Søndergaard

    2006-01-01

    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......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......, 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...

  5. Building energy demand aggregation and simulation tools

    DEFF Research Database (Denmark)

    Gianniou, Panagiota; Heller, Alfred; Rode, Carsten

    2015-01-01

    to neighbourhoods and cities. Buildings occupy a key place in the development of smart cities as they represent an important potential to integrate smart energy solutions. Building energy consumption affects significantly the performance of the entire energy network. Therefore, a realistic estimation...... of the aggregated building energy use will not only ensure security of supply but also enhance the stabilization of national energy balances. In this study, the aggregation of building energy demand was investigated for a real case in Sønderborg, Denmark. Sixteen single-family houses -mainly built in the 1960s......- were examined, all connected to the regional district heating network. The aggregation of building energy demands was carried out according to typologies, being represented by archetype buildings. These houses were modelled with dynamic energy simulation software and with a simplified simulation tool...

  6. Mechanical Properties of Autoclaved Shell-aggregate

    Institute of Scientific and Technical Information of China (English)

    MA Hailong; CUI Chong; LI Xing; Pierre Chevrier; Vanessa Bouchart; TANG Feng

    2011-01-01

    Waste solid propylene oxide sludge(POS)and fly ash were used as main raw material to prepare propylene oxide sludge aggregate(POSA)under the condition of autoclaved(180 ℃,1.0 MPa)curing.Three different test methods namely cylinder compressive strength(CCS),individual aggregate compressive strength(IACS)and strength contribution rate(SCR)proposed were used to characterize the mechanical properties of the autoclaved POSA.POS shell-aggregate with SCR of 94% were prepared under the hydrothermal synthesis and autoclaved curing.The experimental results indicate that CCS and IACS have good consistency in characterizing mechanical properties of POSA.It is suggested that SCR not only can characterize the strength of POSA core,but also can reflect the effect of shell on the performance of POSA.By means of least square method,relationships between CCS and IACS,CCS and SCR,IACS and SCR were deduced.

  7. 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.

  8. 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...... are scheduled using TDMA as the MAC layer protocol. Simulation results show that, SDA gives promising result of energy efficiency and delay as compared with state-of-the-art solutions....

  9. 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.

  10. Influence of polysaccharides on wine protein aggregation.

    Science.gov (United States)

    Jaeckels, Nadine; Meier, Miriam; Dietrich, Helmut; Will, Frank; Decker, Heinz; Fronk, Petra

    2016-06-01

    Polysaccharides are the major high-molecular weight components of wines. In contrast, proteins occur only in small amounts in wine, but contribute to haze formation. The detailed mechanism of aggregation of these proteins, especially in combination with other wine components, remains unclear. This study demonstrates the different aggregation behavior between a buffer and a model wine system by dynamic light scattering. Arabinogalactan-protein, for example, shows an increased aggregation in the model wine system, while in the buffer system a reducing effect is observed. Thus, we could show the importance to examine the behavior of wine additives under conditions close to reality, instead of simpler buffer systems. Additional experiments on melting points of wine proteins reveal that only some isoforms of thaumatin-like proteins and chitinases are involved in haze formation. We can confirm interactions between polysaccharides and proteins, but none of these polysaccharides is able to prevent haze in wine.

  11. SUMO modulation of protein aggregation and degradation

    Directory of Open Access Journals (Sweden)

    Marco Feligioni

    2015-09-01

    Full Text Available Small ubiquitin-like modifier (SUMO conjugation and binding to target proteins regulate a wide variety of cellular pathways. The functional aspects of SUMOylation include changes in protein-protein interactions, intracellular trafficking as well as protein aggregation and degradation. SUMO has also been linked to specialized cellular pathways such as neuronal development and synaptic transmission. In addition, SUMOylation is associated with neurological diseases associated with abnormal protein accumulations. SUMOylation of the amyloid and tau proteins involved in Alzheimer's disease and other tauopathies may contribute to changes in protein solubility and proteolytic processing. Similar events have been reported for α-synuclein aggregates found in Parkinson's disease, polyglutamine disorders such as Huntington's disease as well as protein aggregates found in amyotrophic lateral sclerosis (ALS. This review provides a detailed overview of the impact SUMOylation has on the etiology and pathology of these related neurological diseases.

  12. Chaperone effects on prion and nonprion aggregates.

    Science.gov (United States)

    Rikhvanov, Eugene G; Romanova, Nina V; Chernoff, Yury O

    2007-01-01

    Exposure to high temperature or other stresses induces a synthesis of heat shock proteins. Many of these proteins are molecular chaperones, and some of them help cells to cope with heat-induced denaturation and aggregation of other proteins. In the last decade, chaperones have received increased attention in connection with their role in maintenance and propagation of the Saccharomyces cerevisiae prions, infectious or heritable agents transmitted at the protein level. Recent data suggest that functioning of the chaperones in reactivation of heat-damaged proteins and in propagation of prions is based on the same molecular mechanisms but may lead to different consequences depending on the type of aggregate. In both cases the concerted and balanced action of "chaperones' team," including Hsp104, Hsp70, Hsp40 and possibly other proteins, determines whether a misfolded protein is to be incorporated into an aggregate, rescued to the native state or targeted for degradation.

  13. 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 ...

  14. Process optimization in postcombustion CO{sub 2}-capture by means of repowering and reversible carbonation/calcination cycle

    Energy Technology Data Exchange (ETDEWEB)

    Luis M. Romeo; Juan C. Abanades; Juan C. Ballesteros; Antonio Valero; Jesus M. Escosa; Antonio Gimenez; Cristobal Cortes; Jara Pano [Centro de Investigacion Recursos y Consumos Energeticos (CIRCE), Zaragoza (Spain)

    2006-07-01

    Coal is the major power generation fuel for electricity production. Many countries are heavily dependent on coal, that contributes to about 30% of the European power generation and plays an important role in the European generation industry. The existing coal power plants must be operative to provide energy and take advantage of local resources, but it is necessary to reduce their CO{sub 2} emissions in a feasible manner. It means without introducing excessive economic penalty or reducing their capacity and efficiency. In order to achieve this objective two strategies are highlighted, increase power plant efficiency and capture CO{sub 2} emissions. Increasing power plant efficiency is one of the less expensive ways to reduce CO{sub 2} emissions however it is neither an easy task for existing power plant nor efficiency improvements are large enough to achieve important CO{sub 2} emissions reduction. One of the best methods to significantly increase plant efficiency and also energy production from an economic standpoint is repowering. On the other hand, it is generally accepted that postcombustion CO{sub 2} capture is one of the best suitable technologies for existing coal power plants. It is also well-know that one of the most important gaps in postcombustion capture is the necessity of achieve a process optimization for large-scale power plants. One of these technologies involves the separation of CO{sub 2} from high temperature flue gases using the reversible carbonation reaction of CaO and the calcination of CaCO{sub 3}. In order to achieve a significant abatement of CO{sub 2} emissions without excessive penalty in power plant efficiency, generating capacity and with CO{sub 2} capture cost below 25 EUR/Ton CO{sub 2}, this paper proposes a new, feasible approach to join these two concepts by an optimal integration of the processes within an existing power plant. 6 refs., 1 fig., 2 tabs.

  15. Impact of natural and calcined starfish (Asterina pectinifera) on the stabilization of Pb, Zn and As in contaminated agricultural soil.

    Science.gov (United States)

    Lim, Jung Eun; Sung, Jwa Kyung; Sarkar, Binoy; Wang, Hailong; Hashimoto, Yohey; Tsang, Daniel C W; Ok, Yong Sik

    2017-04-01

    Metal stabilization using soil amendments is an extensively applied, economically viable and environmentally friendly remediation technique. The stabilization of Pb, Zn and As in contaminated soils was evaluated using natural starfish (NSF) and calcined starfish (CSF) wastes at different application rates (0, 2.5, 5.0 and 10.0 wt%). An incubation study was conducted over 14 months, and the efficiency of stabilization for Pb, Zn and As in soil was evaluated by the toxicity characteristic leaching procedure (TCLP) test. The TCLP-extractable Pb was reduced by 76.3-100 and 91.2-100 % in soil treated with NSF and CSF, respectively. The TCLP-extractable Zn was also reduced by 89.8-100 and 93.2-100 % in soil treated with NSF and CSF, respectively. These reductions could be associated with the increased metal adsorption and the formation of insoluble metal precipitates due to increased soil pH following application of the amendments. However, the TCLP-extractable As was increased in the soil treated with NSF, possibly due to the competitive adsorption of phosphorous. In contrast, the TCLP-extractable As in the 10 % CSF treatment was not detectable because insoluble Ca-As compounds might be formed at high pH values. Thermodynamic modeling by visual MINTEQ predicted the formation of ettringite (Ca6Al2(SO4)3(OH)12·26H2O) and portlandite (Ca(OH)2) in the 10 % CSF-treated soil, while SEM-EDS analysis confirmed the needle-like structure of ettringite in which Pb was incorporated and stabilized in the 10 % CSF treatment.

  16. 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.

  17. Protein Aggregation Measurement through Electrical Impedance Spectroscopy

    Science.gov (United States)

    Affanni, A.; Corazza, A.; Esposito, G.; Fogolari, F.; Polano, M.

    2013-09-01

    The paper presents a novel methodology to measure the fibril formation in protein solutions. We designed a bench consisting of a sensor having interdigitated electrodes, a PDMS hermetic reservoir and an impedance meter automatically driven by calculator. The impedance data are interpolated with a lumped elements model and their change over time can provide information on the aggregation process. Encouraging results have been obtained by testing the methodology on K-casein, a protein of milk, with and without the addition of a drug inhibiting the aggregation. The amount of sample needed to perform this measurement is by far lower than the amount needed by fluorescence analysis.

  18. Fault tolerant aggregation for power system services

    DEFF Research Database (Denmark)

    Kosek, Anna Magdalena; Gehrke, Oliver; Kullmann, Daniel

    2013-01-01

    Exploiting the flexibility in distributed energy resources (DER) is seen as an important contribution to allow high penetrations of renewable generation in electrical power systems. However, the present control infrastructure in power systems is not well suited for the integration of a very large...... number of small units. A common approach is to aggregate a portfolio of such units together and expose them to the power system as a single large virtual unit. In order to realize the vision of a Smart Grid, concepts for flexible, resilient and reliable aggregation infrastructures are required...

  19. Interface-Based Service Composition with Aggregation

    DEFF Research Database (Denmark)

    Dalla Preda, Mila; Gabbrielli, Maurizio; Guidi, Claudio;

    2012-01-01

    Service-oriented architectures (SOAs) usually comprehend in-the-middle entities such as proxies or service mediators that compose services abstracting from the order in which they exchange messages. Although widely used, these entities are usually implemented by means of ad-hoc solutions....... 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...

  20. Does it Matter How to Measure Aggregates?

    DEFF Research Database (Denmark)

    Beyer, Andreas; Juselius, Katarina

    . This papers shows, however, that the latter is sensitive to the choice of base year when based on real GDP weights whereas not on nominal GDP weights. A comparison of aggregates calculated with different methods shows that the differences are tiny in absolute value but highly persistent. To investigate...... the impact on the cointegration properties in empirical modelling, the monetary model in Coenen & Vega (2001) based on fixed weights was re-estimated using flexible real and nominal GDP weights. In general, the results remained reasonably robust to the choice of aggregation method...

  1. An Aggregation Approach for Group Multicriteria Assignment

    Directory of Open Access Journals (Sweden)

    George Rigopoulos

    2008-01-01

    Full Text Available We presented an aggregation approach for group multicriteria assignment decisions, where group members express their preferences on problem parameters in numeric format. Individual preferences are aggregated by WOWA operator following the majority concept and a group parameter set is derived that is used as input for the classification algorithm. In addition, we present a numeric example of the approach, demonstrating its applicability. The methodology has been applied to classification problems in business environment, with sufficient results depicting its validity for such problems.

  2. 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.

  3. A comparison of thermal zone aggregation methods

    Energy Technology Data Exchange (ETDEWEB)

    Dobbs, Justin R. [Cornell University; Hencey, Brandon M. [Cornell University

    2012-12-10

    The impact of increasing energy prices on building operation budgets has fueled demand for more energy-efficient structures. Existing building energy simulation tools generate an immense amount of data yet comparatively little knowledge. This paper introduces a framework that allows aggregation-based model reduction to operate on geometric building information models. The resulting aggregation sequence provides designers with faster simulations and affords insight into complex multi-scale thermal interactions. A comparison of the trade-off between simulation speed and accuracy for three hierarchical cluster partitioning methods concludes the discussion.

  4. The effect of heating on mineral composition and grain size distribution of flux calcined porcelanites from the Gafsa-Metlaoui basin, southwestern Tunisia

    Science.gov (United States)

    Saidi, Raja; Tlili, Ali; Jamoussi, Fakher

    2016-12-01

    The porcelanite rock of Ypresian phosphatic series of the Gafsa-Metlaoui basin (south-western Tunisia), is composed mainly of opal CT, and presents a variable percentage of carbonates and fibrous clays. This rock is treated with flux calcination at different temperatures in order to prepare a specific filter aid for cleaning melting sulfur which can be used for the production of sulfuric acid. This work presents the effect of heating on the mineralogy and grain size distribution of carbonate-rich porcelanite (Tm1) and clay-rich porcelanite (Gh) compared to flux calcined silica-rich porcelanite (CHM3) and diatomaceous filtration aids. The porcelanite samples used in this work come from three localities of the Gafsa-Metlaoui basin: Kef El Ghis (Gh), Tamarza (Tm1) and Mides (CHM3). Flux calcination at 1000 °C provokes a mineralogical transformation on carbonate-rich porcelanite samples. The opal CT transforms to opal C and becomes neater and more stable. The Thermal treatment of porcelanite (Tm1) incites also the apparition of new peaks of wollastonite. However, the structural change of opal CT to opal C by heat treatment is blocked for flux calcination of clay-rich porcelanite. The opal CT of fluxing clay-rich porcelanite becomes more ordered without significant change to opal C. The difference between fluxing carbonate-rich porcelanite (Tm1) and fluxing clay-rich porcelanite (Gh) appears also with granulometric distribution histogram of the tow heated samples. All raw samples have unimodal granulometric distribution (1-100 μm). After calcination with alkaline flux at 1000 °C fluxing carbonate-rich porcelanite displays bimodal granulometric distribution and a new mode appears systematically, between 0.1 μm and 1 μm. This occurs for fluxing silica-riche porcelanite and diatomaceous filtration aids as well and corresponds to the opal C formed after heat treatment. Whereas fluxing clay-rich porcelanite present trimodal granulometric distribution and a third mode

  5. 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.

  6. Quality guaranteed aggregation based model predictive control and stability analysis

    Institute of Scientific and Technical Information of China (English)

    LI DeWei; XI YuGeng

    2009-01-01

    The input aggregation strategy can reduce the online computational burden of the model predictive controller. But generally aggregation based MPC controller may lead to poor control quality. Therefore, a new concept, equivalent aggregation, is proposed to guarantee the control quality of aggregation based MPC. From the general framework of input linear aggregation, the design methods of equivalent aggregation are developed for unconstrained and terminal zero constrained MPC, which guarantee the actual control inputs exactly to be equal to that of the original MPC. For constrained MPC, quasi-equivalent aggregation strategies are also discussed, aiming to make the difference between the control inputs of aggregation based MPC and original MPC as small as possible. The stability conditions are given for the quasi-equivalent aggregation based MPC as well.

  7. 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 are a...

  8. Aggregation of MBP in chronic demyelination

    Science.gov (United States)

    Frid, Kati; Einstein, Ofira; Friedman-Levi, Yael; Binyamin, Orli; Ben-Hur, Tamir; Gabizon, Ruth

    2015-01-01

    Objectives Misfolding of key disease proteins to an insoluble state is associated with most neurodegenerative conditions, such as prion, Parkinson, and Alzheimer’s diseases. In this work, and by studying animal models of multiple sclerosis, we asked whether this is also the case for myelin basic protein (MBP) in the late and neurodegenerative phases of demyelinating diseases. Methods To this effect, we tested whether MBP, an essential myelin component, present prion-like properties in animal models of MS, as is the case for Cuprizone-induced chronic demyelination or chronic phases of Experimental Autoimmune Encephalomyelitis (EAE). Results We show here that while total levels of MBP were not reduced following extensive demyelination, part of these molecules accumulated thereafter as aggregates inside oligodendrocytes or around neuronal cells. In chronic EAE, MBP precipitated concomitantly with Tau, a marker of diverse neurodegenerative conditions, including MS. Most important, analysis of fractions from Triton X-100 floatation gradients suggest that the lipid composition of brain membranes in chronic EAE differs significantly from that of naïve mice, an effect which may relate to oxidative insults and subsequently prevent the appropriate insertion and compaction of new MBP in the myelin sheath, thereby causing its misfolding and aggregation. Interpretation Prion-like aggregation of MBP following chronic demyelination may result from an aberrant lipid composition accompanying this pathological status. Such aggregation of MBP may contribute to neuronal damage that occurs in the progressive phase of MS. PMID:26273684

  9. CONSISTENT AGGREGATION IN FOOD DEMAND SYSTEMS

    OpenAIRE

    Levedahl, J. William; Reed, Albert J.; Clark, J. Stephen

    2002-01-01

    Two aggregation schemes for food demand systems are tested for consistency with the Generalized Composite Commodity Theorem (GCCT). One scheme is based on the standard CES classification of food expenditures. The second scheme is based on the Food Guide Pyramid. Evidence is found that both schemes are consistent with the GCCT.

  10. 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.

  11. Familial aggregation of hypospadias: a cohort study

    DEFF Research Database (Denmark)

    Schnack, Tine H; Zdravkovic, Slobodan; Myrup, Charlotte

    2008-01-01

    Hypospadias is one of the most common birth defects. However, its etiology remains largely unknown. The authors investigated the contribution of genetic and environmental factors to familial aggregation of hypospadias. Using Danish health registers, they identified 5,380 boys diagnosed...

  12. Assays for alpha-synuclein aggregation

    DEFF Research Database (Denmark)

    Giehm, Lise; Lorenzen, Nikolai; Otzen, Daniel

    2011-01-01

    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...

  13. 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-chemical...

  14. 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...

  15. Ring aggregation pattern of Human Travel Trips

    CERN Document Server

    Wang, Zi-Yang; Zhu, Peng; Qin, Yong; Jia, Li-Min

    2015-01-01

    Although a lot of attentions have been paid to human mobility, the relationship between travel pattern with city structure is still unclear. Here we probe into this relationship by analyzing the metro passenger trip data.There are two unprecedented findings. One, from the average view a linear law exists between the individual's travel distance with his original distance to city center. The mechanism underlying is a travel pattern we called "ring aggregation", i.e., the daily movement of city passengers is just aggregating to a ring with roughly equal distance to city center.Interestingly, for the round trips the daily travel pattern can be regarded as a switching between the home ring at outer area with the office ring at the inner area. Second, this linear law and ring aggregation pattern seems to be an exclusive characteristic of the metro system. It can not be found in short distance transportation modes, such as bicycle and taxi, neither as multiple transportation modes. This means the ring aggregation p...

  16. 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...

  17. 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...

  18. EFFECT OF AGGREGATION ON VIBRIO CHOLERAE INACTIVATION

    Science.gov (United States)

    Extensive research has shown that microorganisms exhibit increased resistance due to clumping, aggregation, particle association, or modification of antecedent growth conditions. During the course of investigating a major water-borne Vibrio cholerae outbreak in Peru, U.S. EPA inv...

  19. Individual expectations and aggregate macro behavior

    NARCIS (Netherlands)

    Assenza, T.; Heemeijer, P.; Hommes, C.; Massaro, D.

    2013-01-01

    The way in which individual expectations shape aggregate macroeconomic variables is crucial for the transmission and effectiveness of monetary policy. We study the individual expectations formation process and the interaction with monetary policy, within a standard New Keynesian model, by means of l

  20. Individual expectations and aggregate macro behavior

    NARCIS (Netherlands)

    Assenza, T.; Heemeijer, P.; Hommes, C.; Massaro, D.

    2011-01-01

    The way in which individual expectations shape aggregate macroeconomic variables is crucial for the transmission and effectiveness of monetary policy. We study the individual expectations formation process and the interaction with monetary policy, within a standard New Keynesian model, by means of l

  1. 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 eg

  2. 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 aggr

  3. Nonlinear Evolution of Aggregates with Inextensible Constraints

    Institute of Scientific and Technical Information of China (English)

    Ming-XiangCHEN; WeiYANG; 等

    1996-01-01

    Crystalline and semicrystalline polymers are formed as aggregates of grains with evolving inextensible axes.This inextensible constratint leads to texture evolution under large plastic deformation.This paper reveals the nonlinear texture evolution of crystalline polymers under axi-symmetric straining.

  4. 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…

  5. 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...

  6. A discrete anisotropic model for Scheibe aggregates

    Directory of Open Access Journals (Sweden)

    O. Bang

    1991-05-01

    Full Text Available A discrete anisotropic nonlinear model for the dynamics of Scheibe aggregates is investigated. The collapse of the collective excitations found by Möbius and Kuhn is described as a shrinking ring wave, which is eventually absorbed by an acceptor molecule. An optimal acceptor loss is found.

  7. 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...

  8. 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…

  9. Thermodynamics of Micellization of Surfactants of Low Aggregation Number: The Aggregation of Propranolol Hydrochloride.

    Science.gov (United States)

    Mosquera; Ruso; Attwood; Jones; Prieto; Sarmiento

    1999-02-01

    The self-association of propranolol hydrochloride in aqueous solution has been studied as a function of temperature. The critical concentration (C*) and the degree of ionization (alpha) were determined by conductivity measurements at temperatures over the range 298.15 to 313.15 K. The enthalpy change on aggregation in water was measured by microcalorimetry. To calculate changes in the thermodynamic properties of aggregation the mass action model for high and low aggregation numbers was applied, the latter model giving better agreement between experimental and theoretical enthalpy changes. Copyright 1999 Academic Press.

  10. Porous nano-structured Co3O4 anode materials generated from coordination-driven self-assembled aggregates for advanced lithium ion batteries.

    Science.gov (United States)

    Ge, Danhua; Geng, Hongbo; Wang, Jiaqing; Zheng, Junwei; Pan, Yue; Cao, Xueqin; Gu, Hongwei

    2014-08-21

    A simple and scalable coordination-derived method for the synthesis of porous Co3O4 hollow nanospheres is described here. The initially formed coordination-driven self-assembled aggregates (CDSAAs) could act as the precursor followed by calcination treatment. Then the porous hollow Co3O4 nanospheres are obtained, in which the primary Co3O4 nanoparticles are inter-dispersed. When the nanospheres are used as anode materials for lithium storage, they show excellent coulombic efficiency, high lithium storage capacity and superior cycling performance. In view of the facile synthesis and excellent electrochemical performance obtained, this protocol to fabricate special porous hollow frameworks could be further extended to other metal oxides and is expected to improve the practicality of superior cycle life anode materials with large volume excursions for the development of the next generation of LIBs.

  11. 固定床煅烧炉中载铯亚铁氰化钛钾的热分解研究%Thermal Decomposition of Potassium Titanium Hexacyanoferrate (Ⅱ) Loaded with Cesium in a Fixed Bed Calciner

    Institute of Scientific and Technical Information of China (English)

    冯孝贵; 景山; 吴秋林; 陈靖; 宋崇立

    2007-01-01

    The thermal decomposition of potassium titanium hexacyanoferrate(Ⅱ) (KTiFC) loaded with cesium (referred to as Used Exchanget,or UE) was studied at different flow rate of air in a fixed bed calciner.The calcination process consisted of four stages:ambient temperature-180℃ (stage Ⅰ),180-250℃ (stage Ⅱ),250-400℃ (stage Ⅲ),and constant 400℃ (stage Ⅳ).The most intense reaction occurred in stage Ⅱ.The rate of thermal decomposition was controlled,depending on the O2 flux,by O2 or CN concentration in different stages.Results from differential thermal analysis (DTA) showed that the calcination reaction of the anhydrous UE was exotlaemic, with an approximate heat output of 4.6kJ·g-1,which was so large to cause the possible agglomeration of calcined residues.The agglomeration could be avoided by enhancing heat transfer and controlling the O2 flux.It was found that there was no cyanides in the calcined residues and no CN-bearing gases such as HCN and (CN)2 in the off-gas.It seemed that the catalytic oxidation furnace behind the fixed bed calciner could be cancelled.

  12. 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.

  13. Copper-triggered aggregation of ubiquitin.

    Science.gov (United States)

    Arnesano, Fabio; Scintilla, Simone; Calò, Vincenza; Bonfrate, Elena; Ingrosso, Chiara; Losacco, Maurizio; Pellegrino, Teresa; Rizzarelli, Enrico; Natile, Giovanni

    2009-09-16

    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's, amyotrophic

  14. 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

  15. 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.

  16. Small file aggregation in a parallel computing system

    Science.gov (United States)

    Faibish, Sorin; Bent, John M.; Tzelnic, Percy; Grider, Gary; Zhang, Jingwang

    2014-09-02

    Techniques are provided for small file aggregation in a parallel computing system. An exemplary method for storing a plurality of files generated by a plurality of processes in a parallel computing system comprises aggregating the plurality of files into a single aggregated file; and generating metadata for the single aggregated file. The metadata comprises an offset and a length of each of the plurality of files in the single aggregated file. The metadata can be used to unpack one or more of the files from the single aggregated file.

  17. 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.

  18. Soil structure and soil organic matter: I. Distribution of aggregate size classes and aggregate associated carbon

    OpenAIRE

    J. Six; K. Paustian; Elliott, E.T.; C. Combrink

    2000-01-01

    Metadata only record This study compares aggregate size and carbon in three different soils, each with three tillage treatments (native vegetation (NV), no-tillage (NT), and conventional tillage (CT)).

  19. 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)

  20. 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.