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Sample records for 5a molecular sieve

  1. Continuously adjustable, molecular-sieving “gate” on 5A zeolite for distinguishing small organic molecules by size

    DOE PAGESBeta

    Song, Zhuonan; Huang, Yi; Xu, Weiwei L.; Wang, Lei; Bao, Yu; Li, Shiguang; Yu, Miao

    2015-09-11

    Zeolites/molecular sieves with uniform, molecular-sized pores are important for many adsorption-based separation processes. Pore size gaps, however, exist in the current zeolite family. This leads to a great challenge of separating molecules with size differences at ~0.01 nm level. Here, we report a novel concept, pore misalignment, to form a continuously adjustable, molecular-sieving “gate” at the 5A zeolite pore entrance without sacrificing the internal capacity. Misalignment of the micropores of the alumina coating with the 5A zeolite pores was related with and facilely adjusted by the coating thickness. For the first time, organic molecules with sub-0.01 nm size differences weremore » effectively distinguished via appropriate misalignment. Lastly, this novel concept may have great potential to fill the pore size gaps of the zeolite family and realize size-selective adsorption separation.« less

  2. Continuously adjustable, molecular-sieving “gate” on 5A zeolite for distinguishing small organic molecules by size

    SciTech Connect

    Song, Zhuonan; Huang, Yi; Xu, Weiwei L.; Wang, Lei; Bao, Yu; Li, Shiguang; Yu, Miao

    2015-09-11

    Zeolites/molecular sieves with uniform, molecular-sized pores are important for many adsorption-based separation processes. Pore size gaps, however, exist in the current zeolite family. This leads to a great challenge of separating molecules with size differences at ~0.01 nm level. Here, we report a novel concept, pore misalignment, to form a continuously adjustable, molecular-sieving “gate” at the 5A zeolite pore entrance without sacrificing the internal capacity. Misalignment of the micropores of the alumina coating with the 5A zeolite pores was related with and facilely adjusted by the coating thickness. For the first time, organic molecules with sub-0.01 nm size differences were effectively distinguished via appropriate misalignment. Lastly, this novel concept may have great potential to fill the pore size gaps of the zeolite family and realize size-selective adsorption separation.

  3. Continuously Adjustable, Molecular-Sieving “Gate” on 5A Zeolite for Distinguishing Small Organic Molecules by Size

    PubMed Central

    Song, Zhuonan; Huang, Yi; Xu, Weiwei L.; Wang, Lei; Bao, Yu; Li, Shiguang; Yu, Miao

    2015-01-01

    Zeolites/molecular sieves with uniform, molecular-sized pores are important for many adsorption-based separation processes. Pore size gaps, however, exist in the current zeolite family. This leads to a great challenge of separating molecules with size differences at ~0.01 nm level. Here, we report a novel concept, pore misalignment, to form a continuously adjustable, molecular-sieving “gate” at the 5A zeolite pore entrance without sacrificing the internal capacity. Misalignment of the micropores of the alumina coating with the 5A zeolite pores was related with and facilely adjusted by the coating thickness. For the first time, organic molecules with sub-0.01 nm size differences were effectively distinguished via appropriate misalignment. This novel concept may have great potential to fill the pore size gaps of the zeolite family and realize size-selective adsorption separation. PMID:26358480

  4. Space station molecular sieve development

    NASA Technical Reports Server (NTRS)

    Chang, C.; Rousseau, J.

    1986-01-01

    An essential function of a space environmental control system is the removal of carbon dioxide (CO2) from the atmosphere to control the partial pressure of this gas at levels lower than 3 mm Hg. The use of regenerable solid adsorbents for this purpose was demonstrated effectively during the Skylab mission. Earlier sorbent systems used zeolite molecular sieves. The carbon molecular sieve is a hydrophobic adsorbent with excellent potential for space station application. Although carbon molecular sieves were synthesized and investigated, these sieves were designed to simulate the sieving properties of 5A zeolite and for O2/N2 separation. This program was designed to develop hydrophobic carbon molecular sieves for CO2 removal from a space station crew environment. It is a first phase effort involved in sorbent material development and in demonstrating the utility of such a material for CO2 removal on space stations. The sieve must incorporate the following requirements: it must be hydrophobic; it must have high dynamic capacity for carbon dioxide at the low partial pressure of the space station atmosphere; and it must be chemiclly stable and will not generate contaminants.

  5. Molecular Sieve Regeneration System (MSRS)

    SciTech Connect

    Nasise, J.E.; Anderson, J.L. ); Naruse, Y. )

    1992-01-01

    A Molecular Sieve Regeneration System (MSRS) was added to the existing Tritium Waste Treatment system (TWT) within the Tritium Systems Test Assembly (TSTA) at Los Alamos National Laboratory. The Department of Energy (DOE) no longer allows inventory by difference'' for radioactive wastes that are to be buried. The MSRS was designed and built to comply with this requirement. Within the TWT, water is generated by the catalytic conversion of hydrogen isotopes and removed by molecular sieve trapping prior to release to the environment. Molecular sieve regeneration is required to remove the trapped water and to rejuvenate the beds. The MSRS permits the collection and direct tritium assay of regenerated tritiated water from molecular sieve beds. This paper describes the MSRS in detail and how it is interfaced with the TWT.

  6. Molecular Sieve Regeneration System (MSRS)

    SciTech Connect

    Nasise, J.E.; Anderson, J.L.; Naruse, Y.

    1992-03-01

    A Molecular Sieve Regeneration System (MSRS) was added to the existing Tritium Waste Treatment system (TWT) within the Tritium Systems Test Assembly (TSTA) at Los Alamos National Laboratory. The Department of Energy (DOE) no longer allows ``inventory by difference`` for radioactive wastes that are to be buried. The MSRS was designed and built to comply with this requirement. Within the TWT, water is generated by the catalytic conversion of hydrogen isotopes and removed by molecular sieve trapping prior to release to the environment. Molecular sieve regeneration is required to remove the trapped water and to rejuvenate the beds. The MSRS permits the collection and direct tritium assay of regenerated tritiated water from molecular sieve beds. This paper describes the MSRS in detail and how it is interfaced with the TWT.

  7. Niobate-based octahedral molecular sieves

    DOEpatents

    Nenoff, Tina M.; Nyman, May D.

    2006-10-17

    Niobate-based octahedral molecular sieves having significant activity for multivalent cations and a method for synthesizing such sieves are disclosed. The sieves have a net negatively charged octahedral framework, comprising niobium, oxygen, and octahedrally coordinated lower valence transition metals. The framework can be charge balanced by the occluded alkali cation from the synthesis method. The alkali cation can be exchanged for other contaminant metal ions. The ion-exchanged niobate-based octahedral molecular sieve can be backexchanged in acidic solutions to yield a solution concentrated in the contaminant metal. Alternatively, the ion-exchanged niobate-based octahedral molecular sieve can be thermally converted to a durable perovskite phase waste form.

  8. Niobate-based octahedral molecular sieves

    DOEpatents

    Nenoff, Tina M.; Nyman, May D.

    2003-07-22

    Niobate-based octahedral molecular sieves having significant activity for multivalent cations and a method for synthesizing such sieves are disclosed. The sieves have a net negatively charged octahedral framework, comprising niobium, oxygen, and octahedrally coordinated lower valence transition metals. The framework can be charge balanced by the occluded alkali cation from the synthesis method. The alkali cation can be exchanged for other contaminant metal ions. The ion-exchanged niobate-based octahedral molecular sieve can be backexchanged in acidic solutions to yield a solution concentrated in the contaminant metal. Alternatively, the ion-exchanged niobate-based octahedral molecular sieve can be thermally converted to a durable perovskite phase waste form.

  9. Thermodynamics of formation of molecular sieves

    NASA Astrophysics Data System (ADS)

    Piccione, Patrick Manuel

    2002-09-01

    Thermodynamic investigations are undertaken to better understand the energetic differences amongst molecular sieve frameworks and the mechanisms and interactions important in molecular sieve self-assembly. The enthalpies relative to quartz at 298.15 K are determined by high-temperature solution calorimetry for a collection of calcined pure-silica molecular sieves with diverse structural features. SiO2 molecular sieves are shown to be only modestly (6.8--14.4 kJ/mol) metastable with respect to quartz. The available thermal energy at typical synthesis conditions is RT = 3.5 kJ/mol. A strong correlation between enthalpy and molar volume is observed. The entropies of four pure-silica molecular sieves with a wide range of molar volumes are determined by heat capacity measurements from 5 to 400 K. The entropies of these structures are almost identical (3.2--4.2 J · K-1mol-1 above quartz). The enthalpy and entropy data are combined to calculate the Gibbs free energies of transition from quartz to eight other silica polymorphs. The molecular sieve Gibbs free energies are only 5.5--12.6 kJ/mol less stable than quartz. Therefore, there are no significant thermodynamic barriers to transformations between silica polymorphs. This result suggests that structure-directing agents (SDAs) in molecular sieves syntheses do not serve to stabilize otherwise very unstable phases. Interaction enthalpies between inorganic frameworks and organic SDAs are measured by HF solution calorimetry for six molecular sieve/SDA pairs. The enthalpies are only moderately exothermic (-1.1 to -5.9 kJ/mol SiO2), as expected if the predominant interactions are silica/hydrocarbon van der Waals contacts. Interaction entropies are estimated for three framework/SDA pairs, and together with the interaction enthalpies allow the calculation of the Gibbs free energies of interaction. The latter values range from -2.0 to -5.4 kJ/mol SiO2. This energy range is comparable to that observed for the SiO2 frameworks

  10. Carbon fiber composite molecular sieves

    SciTech Connect

    Burchell, T.D.; Rogers, M.R.; Williams, A.M.

    1996-06-01

    The removal of CO{sub 2} is of significance in several energy applications. The combustion of fossil fuels, such as coal or natural gas, releases large volumes of CO{sub 2} to the environment. Several options exist to reduce CO{sub 2} emissions, including substitution of nuclear power for fossil fuels, increasing the efficiency of fossil plants and capturing the CO{sub 2} prior to emission to the environment. All of these techniques have the attractive feature of limiting the amount of CO{sub 2} emitted to the atmosphere, but each has economic, technical, or societal limitations. In the production of natural gas, the feed stream from the well frequently contains contaminants and diluents which must be removed before the gas can enter the pipeline distribution system. Notable amongst these diluent gasses is CO{sub 2}, which has no calorific value. Currently, the pipeline specification calls for <2 mol % CO{sub 2} in the gas. Gas separation is thus a relevant technology in the field of energy production. A novel separation system based on a parametric swing process has been developed that utilizes the unique combination of properties exhibited by our carbon fiber composite molecular sieve (CFCMS).

  11. Enhanced Molecular Sieve CO2 Removal Evaluation

    NASA Technical Reports Server (NTRS)

    Rose, Susan; ElSherif, Dina; MacKnight, Allen

    1996-01-01

    The objective of this research is to quantitatively characterize the performance of two major types of molecular sieves for two-bed regenerative carbon dioxide removal at the conditions compatible with both a spacesuit and station application. One sorbent is a zeolite-based molecular sieve that has been substantially improved over the materials used in Skylab. The second sorbent is a recently developed carbon-based molecular sieve. Both molecular sieves offer the potential of high payoff for future manned missions by reducing system complexity, weight (including consumables), and power consumption in comparison with competing concepts. The research reported here provides the technical data required to improve CO2 removal systems for regenerative life support systems for future IVA and EVA missions.

  12. Chlorodifluoromethane equilibrium on 13X molecular sieve

    NASA Astrophysics Data System (ADS)

    Carlile, Donna L.; Mahle, John J.; Buettner, Leonard C.; Tevault, David E.; Friday, David K.

    1994-08-01

    Adsorption phase equilibrium data are required for evaluating any adsorption-based gas separation process. The U.S. Army Edgewood Research, Development and Engineering Center is currently measuring adsorption phase equilibrium data for a variety of chemical warfare agents and their surrogates on adsorbent materials to correlate physical properties to filtration/separation efficiencies of each vapor on each adsorbent. This report details the adsorption phase equilibrium data measured for chlorodifluoromethane (R-22) on 13X Molecular Sieve. The 13X Molecular Sieve is a candidate adsorbent for future military air purification systems employing the pressure-swing adsorption separation process.

  13. Catalytic cracking catalysts using silicoaluminophosphate molecular sieves

    SciTech Connect

    Pellet, R.J.; Coughlin, P.K.; Staniulis, M.T.; Long, G.N.; Rabo, J.A.

    1987-05-19

    A cracking catalyst is described comprising: a silicoaluminophosphate molecular sieve of U.S. Pat. No. 4,440,871 characterized in its calcined form by an adsorption of isobutane of at least 2 percent by weight at a pressure of 500 torr and a temperature of 20/sup 0/C and having an effective amount of the cations associated with the silicoaluminophosphate molecular sieve selected from the group consisting of H+, ammonium, Group IIA, groups IIIB to VIIB, cerium, lanthanum, praseodymium, neodymium, and promethium.

  14. Molecular sieving silica membrane fabrication process

    DOEpatents

    Raman, N.K.; Brinker, C.J.

    1999-08-10

    A process is described for producing a molecular sieve silica membrane comprising depositing a hybrid organic-inorganic polymer comprising at least one organic constituent and at least one inorganic constituent on a porous substrate material and removing at least a portion of the at least one organic constituent of the hybrid organic-inorganic polymer, forming a porous film. 11 figs.

  15. Molecular sieving silica membrane fabrication process

    DOEpatents

    Raman, Narayan K.; Brinker, Charles Jeffrey

    1999-01-01

    A process for producing a molecular sieve silica membrane comprising depositing a hybrid organic-inorganic polymer comprising at least one organic constituent and at least one inorganic constituent on a porous substrate material and removing at least a portion of the at least one organic constituent of the hybrid organic-inorganic polymer, forming a porous film.

  16. Molecular sieving silica membrane fabrication process

    DOEpatents

    Raman, Narayan K.; Brinker, Charles Jeffrey

    1998-01-01

    A process for producing a molecular sieve silica membrane comprising depositing a hybrid organic-inorganic polymer comprising at least one organic constituent and at least one inorganic constituent on a porous substrate material and removing at least a portion of the at least one organic constituent of the hybrid organic-inorganic polymer, forming a porous film.

  17. 21 CFR 173.40 - Molecular sieve resins.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 3 2011-04-01 2011-04-01 false Molecular sieve resins. 173.40 Section 173.40 Food... Polymer Substances and Polymer Adjuvants for Food Treatment § 173.40 Molecular sieve resins. Molecular sieve resins may be safely used in the processing of food under the following prescribed conditions:...

  18. 21 CFR 173.40 - Molecular sieve resins.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Molecular sieve resins. 173.40 Section 173.40 Food... Polymer Substances and Polymer Adjuvants for Food Treatment § 173.40 Molecular sieve resins. Molecular sieve resins may be safely used in the processing of food under the following prescribed conditions:...

  19. Adsorption of gases on carbon molecular sieves

    SciTech Connect

    Vyas, S.N.; Patwardhan, S.R.; Vijayalakshmi, S. . Dept. of Chemical Engineering); Ganesh, K.S. )

    1994-12-01

    Adsorption on carbon molecular sieves (CMS) prepared by coke deposition has become an interesting area of adsorption due to its microporous nature and favorable separation factor on size and shape selectivity basis for many gaseous systems. In the present work CMS was synthesized from coconut shell through three major steps, namely, carbonization, activation, and coke deposition by hydrocarbon cracking. The crushed, washed, and sieved granules of coconut shell (particle size 2--3 mm) were pretreated with sodium silicate solution and oven-dried at 150 C to create the inorganic sites necessary for coke deposition. Carbonization and activation of the dried granules were carried out at 800 C, for 30 min each. The activated char thus produced was subjected to hydrocarbon cracking at 600 C for periods varying from 30 to 180 min. The product samples were characterized in terms of adsorption isotherm, kinetic adsorption curve, surface area, pore volume, pore size distribution, and characteristic energy for adsorption by using O[sub 2], N[sub 2], C[sub 2]H[sub 2], CO[sub 2], C[sub 3]H[sub 6], and CH[sub 4].

  20. Octahedral molecular sieve sorbents and catalysts

    SciTech Connect

    Li, Liyu; King, David L

    2010-04-20

    Octahedral molecular sieve sorbents and catalysts are disclosed, including silver hollandite and cryptomelane. These materials can be used, for example, to catalyze the oxidation of CO.sub.x (e.g., CO), NO.sub.x (e.g., NO), hydrocarbons (e.g., C.sub.3H.sub.6) and/or sulfur-containing compounds. The disclosed materials also may be used to catalyze other reactions, such as the reduction of NO.sub.2. In some cases, the disclosed materials are capable of sorbing certain products from the reactions they catalyze. Silver hollandite, in particular, can be used to remove a substantial portion of certain sulfur-containing compounds from a gas or liquid by catalysis and/or sorption. The gas or liquid can be, for example, natural gas or a liquid hydrocarbon.

  1. Silicotitanate molecular sieve and condensed phases

    DOEpatents

    Nenoff, Tina M.; Nyman, May D.

    2002-01-01

    A new microporous crystalline molecular sieve material having the formula Cs.sub.3 TiSi.sub.3 O.sub.95.cndot.3H.sub.2 O and its hydrothermally condensed phase, Cs.sub.2 TiSi.sub.6 O.sub.15, are disclosed. The microporous material can adsorb divalent ions of radionuclides or other industrial metals such as chromium, nickel, lead, copper, cobalt, zinc, cadmium, barium, and mercury, from aqueous or hydrocarbon solutions. The adsorbed metal ions can be leached out for recovery purposes or the microporous material can be hydrothermally condensed to a radiation resistant, structurally and chemically stable phase which can serve as a storage waste form for radionuclides.

  2. Production of carbon molecular sieves from illinois coals. An assessment

    USGS Publications Warehouse

    Lizzio, Anthony A.; Rostam-Abadi, Massoud

    1991-01-01

    Chars were produced from an Illinois No. 2 bituminous coal under various pyrolysis and activation conditions and tested for their molecular sieve properties. The amount of N2 compared to the amount of CO2 adsorbed by each char was used as a preliminary indicator of its molecular sieve properties. This relatively simple, but apparently useful test was confirmed by successfully characterizing the well-known molecular sieve properties of a commercial zeolite and molecular sieve carbon. In addition, coal chars having relatively high surface areas (800-1800 m2/g) were produced and tested for their molecular sieving capabilities. These carbon materials, which have high adsorption capacities and relatively narrow pore size distributions, should be ideal candidates for the commercial production of CMS.

  3. Copper modified carbon molecular sieves for selective oxygen removal

    NASA Technical Reports Server (NTRS)

    Sharma, Pramod K. (Inventor); Seshan, Panchalam K. (Inventor)

    1992-01-01

    Carbon molecular sieves modified by the incorporation of finely divided elemental copper useful for the selective sorption of oxygen at elevated temperatures. The carbon molecular sieves can be regenerated by reduction with hydrogen. The copper modified carbon molecular sieves are prepared by pyrolysis of a mixture of a copper-containing material and polyfunctional alcohol to form a sorbent precursor. The sorbent precursors are then heated and reduced to produce copper modified carbon molecular sieves. The copper modified carbon molecular sieves are useful for sorption of all concentrations of oxygen at temperatures up to about 200.degree. C. They are also useful for removal of trace amount of oxygen from gases at temperatures up to about 600.degree. C.

  4. Copper crystallite in carbon molecular sieves for selective oxygen removal

    NASA Technical Reports Server (NTRS)

    Sharma, Pramod K. (Inventor); Seshan, Panchalam K. (Inventor)

    1993-01-01

    Carbon molecular sieves modified by the incorporation of finely divided elemental copper useful for the selective sorption of oxygen at elevated temperatures. The carbon molecular sieves can be regenerated by reduction with hydrogen. The copper modified carbon molecular sieves are prepared by pyrolysis of a mixture of a copper-containing material and polyfurfuryl alcohol to form a sorbent precursor. The sorbent precursors are then heated and reduced to produce copper modified carbon molecular sieves. The copper modified carbon molecular sieves are useful for sorption of all concentrations of oxygen at temperatures up to about 200.degree. C. They are also useful for removal of trace amount of oxygen from gases at temperatures up to about 600.degree. C.

  5. Selective molecular sieving through porous graphene

    NASA Astrophysics Data System (ADS)

    Koenig, Steven P.; Wang, Luda; Pellegrino, John; Bunch, J. Scott

    2012-12-01

    Membranes act as selective barriers and play an important role in processes such as cellular compartmentalization and industrial-scale chemical and gas purification. The ideal membrane should be as thin as possible to maximize flux, mechanically robust to prevent fracture, and have well-defined pore sizes to increase selectivity. Graphene is an excellent starting point for developing size-selective membranes because of its atomic thickness, high mechanical strength, relative inertness and impermeability to all standard gases. However, pores that can exclude larger molecules but allow smaller molecules to pass through would have to be introduced into the material. Here, we show that ultraviolet-induced oxidative etching can create pores in micrometre-sized graphene membranes, and the resulting membranes can be used as molecular sieves. A pressurized blister test and mechanical resonance are used to measure the transport of a range of gases (H2, CO2, Ar, N2, CH4 and SF6) through the pores. The experimentally measured leak rate, separation factors and Raman spectrum agree well with models based on effusion through a small number of ångstrom-sized pores.

  6. Antibacterial mesoporous molecular sieves modified with polymeric N-halamine.

    PubMed

    Wang, Yingfeng; Li, Lin; Liu, Ying; Ren, Xuehong; Liang, Jie

    2016-12-01

    In this research, a new kind of porous N-halamine material with high antibacterial efficacies was prepared. Poly [5,5-dimethyl-3-(3'-triethoxysilylpropyl)-hydantoin] (PSPH), an N-halamine precursor, was synthesized and grafted onto the surface of mesoporous molecular sieves (SBA-15). The mesoporous molecular sieves modified with the N-halamine polymer could be rendered biocidal upon exposure to dilute household bleach. The modified mesoporous molecular sieves were characterized by SEM, TEM, FTIR, XPS, TGA, XRD and BET analysis. It was found that the PSPH has been successfully grafted on the surface of mesoporous molecular sieves, and the morphology and structure of the modified mesoporous molecular sieves were slightly affected. The N-halamine modified mesoporous molecular sieves showed excellent antibacterial property, and inactivated 100% of S. aureus and E. coli O157:H7 with 8.05 and 7.92 log reductions within 1min of contact, respectively. The modified SBA-15 with high-antibacterial efficiency has potential application in water treatment and biomaterials areas. PMID:27612805

  7. A 99 percent purity molecular sieve oxygen generator

    NASA Technical Reports Server (NTRS)

    Miller, G. W.

    1991-01-01

    Molecular sieve oxygen generating systems (MSOGS) have become the accepted method for the production of breathable oxygen on military aircraft. These systems separate oxygen for aircraft engine bleed air by application of pressure swing adsorption (PSA) technology. Oxygen is concentrated by preferential adsorption in nitrogen in a zeolite molecular sieve. However, the inability of current zeolite molecular sieves to discriminate between oxygen and argon results in an oxygen purity limitations of 93-95 percent (both oxygen and argon concentrate). The goal was to develop a new PSA process capable of exceeding the present oxygen purity limitations. A novel molecular sieve oxygen concentrator was developed which is capable of generating oxygen concentrations of up to 99.7 percent directly from air. The process is comprised of four absorbent beds, two containing a zeolite molecular sieve and two containing a carbon molecular sieve. This new process may find use in aircraft and medical breathing systems, and industrial air separation systems. The commercial potential of the process is currently being evaluated.

  8. Molecular Sieve Bench Testing and Computer Modeling

    NASA Technical Reports Server (NTRS)

    Mohamadinejad, Habib; DaLee, Robert C.; Blackmon, James B.

    1995-01-01

    The design of an efficient four-bed molecular sieve (4BMS) CO2 removal system for the International Space Station depends on many mission parameters, such as duration, crew size, cost of power, volume, fluid interface properties, etc. A need for space vehicle CO2 removal system models capable of accurately performing extrapolated hardware predictions is inevitable due to the change of the parameters which influences the CO2 removal system capacity. The purpose is to investigate the mathematical techniques required for a model capable of accurate extrapolated performance predictions and to obtain test data required to estimate mass transfer coefficients and verify the computer model. Models have been developed to demonstrate that the finite difference technique can be successfully applied to sorbents and conditions used in spacecraft CO2 removal systems. The nonisothermal, axially dispersed, plug flow model with linear driving force for 5X sorbent and pore diffusion for silica gel are then applied to test data. A more complex model, a non-darcian model (two dimensional), has also been developed for simulation of the test data. This model takes into account the channeling effect on column breakthrough. Four FORTRAN computer programs are presented: a two-dimensional model of flow adsorption/desorption in a packed bed; a one-dimensional model of flow adsorption/desorption in a packed bed; a model of thermal vacuum desorption; and a model of a tri-sectional packed bed with two different sorbent materials. The programs are capable of simulating up to four gas constituents for each process, which can be increased with a few minor changes.

  9. Mesoporous Molecular Sieves as Supports for Metathesis Catalysts

    NASA Astrophysics Data System (ADS)

    Balcar, Hynek; Cejka, Jirí

    Mesoporous molecular sieves represent a new family of inorganic oxides with regular nanostructure, large surface areas, large void volumes, and narrow pore size distribution of mesopores. These materials offer new possibilities for designing highly active and selective catalysts for olefin metathesis and metathesis polymerization. Siliceous sieves MCM-41, MCM-48, SBA-15, and organized mesoporous alumina (OMA) were used as supports for preparation of new molybdenum and rhenium oxide catalysts, as well as for heterogenization of well-defined homogeneous catalysts.

  10. Carbon molecular sieves for air separation from Nomex aramid fibers.

    PubMed

    Villar-Rodil, Silvia; Martínez-Alonso, Amelia; Tascón, Juan M D

    2002-10-15

    Activated carbon fibers prepared from aramid fibers have proved to possess outstanding homogeneity in pore size, most of all when Nomex aramid fiber is used as precursor. Taking advantage of this feature, microporous carbon molecular sieves for air separation have been prepared through carbon vapor deposition of benzene on Nomex-derived carbon fibers activated to two different burnoff degrees. Carbon molecular sieves with good selectivity for this separation and showing acceptable adsorption capacities were obtained from ACFs activated to the two burnoff degrees chosen. PMID:12702417

  11. Double rotation NMR studies of zeolites and aluminophosphate molecular sieves

    SciTech Connect

    Jelinek, R. |

    1993-07-01

    Goal is to study the organization and structures of guest atoms and molecules and their reactions on internal surfaces within pores of zeolites and aluminophosphate molecular sieves. {sup 27}Al and {sup 23}Na double rotation NMR (DOR) is used since it removes the anisotropic broadening in NMR spectra of quadrupolar nuclei, thus increasing resolution. This work concentrates on probing aluminum framework atoms in aluminophosphate molecular sieves and sodium extra framework cations in porous aluminosilicates. In aluminophosphates, ordering and electronic environments of the framework {sup 27}Al nuclei are modified upon adsorption of water molecules within the channels; a relation is sought between the sieve channel topology and the organization of adsorbed water, as well as the interaction between the Al nuclei and the water molecules. Extra framework Na{sup +} cations are directly involved in adsorption processes and reactions in zeolite cavities.

  12. Carbon fiber composite molecular sieve electrically regenerable air filter media

    DOEpatents

    Wilson, Kirk A.; Burchell, Timothy D.; Judkins, Roddie R.

    1998-01-01

    An electrically regenerable gas filter system includes a carbon fiber composite molecular sieve (CFCMS) filter medium. After a separate medium-efficiency pre-filter removes particulate from the supply airstream, the CFCMS filter sorbs gaseous air pollutants before the air is recirculated to the space. When saturated, the CFCMS media is regenerated utilizing a low-voltage current that is caused to pass through the filter medium.

  13. Carbon fiber composite molecular sieve electrically regenerable air filter media

    DOEpatents

    Wilson, K.A.; Burchell, T.D.; Judkins, R.R.

    1998-10-27

    An electrically regenerable gas filter system includes a carbon fiber composite molecular sieve (CFCMS) filter medium. After a separate medium-efficiency pre-filter removes particulate from the supply air stream, the CFCMS filter sorbs gaseous air pollutants before the air is recirculated to the space. When saturated, the CFCMS media is regenerated utilizing a low-voltage current that is caused to pass through the filter medium. 3 figs.

  14. Production of carbon molecular sieves from Illinois coal

    USGS Publications Warehouse

    Lizzio, A.A.; Rostam-Abadi, M.

    1993-01-01

    Carbon molecular sieves (CMS) have become an increasingly important class of adsorbents for application in the separation of gas molecules that vary in size and shape. A study is in progress at the Illinois State Geological Survey to determine whether Illinois basin coals are suitable feedstocks for the production of CMS and to evaluate their potential application in gas separation processes of commercial importance. Chars were prepared from Illinois coal in a fixed-bed reactor under a wide range of heat treatment and activation conditions. The effects of various coal/char pretreatments, including coal demineralization, preoxidation, char activation, and carbon deposition, on the molecular sieve properties of the chars were also investigated. Chars with commercially significant BET surface areas of 1500 m2/g were produced by chemical activation using potassium hydroxide as the activant. These high-surface-area (HSA) chars had more than twice the adsorption capacity of commercial carbon and zeolite molecular sieves. The kinetics of adsorption of various gases, e.g., N2, O2, CO2, CH4, CO and H2, on these chars at 25??C was measured. The O2/N2 molecular sieve properties of one char prepared without chemical activation were similar to those of a commercial CMS. On the other hand, the O2/N2 selectivity of the HSA char was comparable to that of a commercial activated carbon, i.e., essentially unity. Carbon deposition, using methane as the cracking gas, increased the O2/N2 selectivity of the HSA char, but significantly decreased its adsorption capacity. Several chars showed good potential for efficient CO2/CH4 separation; both a relatively high CO2 adsorption capacity and CO2/CH4 selectivity were achieved. The micropore size distribution of selected chars was estimated by equilibrium adsorption of carbon dioxide, n-butane and iso-butane at O??C. The extent of adsorption of each gas corresponded to the effective surface area contained in pores with diameters greater than 3

  15. Nanoscale octahedral molecular sieves: Syntheses, characterization, and applications

    NASA Astrophysics Data System (ADS)

    Liu, Jia

    The major part of this research consists of studies on novel synthesis methods, characterization, and catalytic applications of nanoscale manganese oxide octahedral molecular sieves. The second part involves studies of new applications of bulk porous molecular sieve and layered materials (MSLM), zeolites, and inorganic powder materials for diminishing wound bleeding. Manganese oxide octahedral molecular sieves (OMS) are very important microporous materials. They have been used widely as bulk materials in catalysis, separations, chemical sensors, and batteries, due to their unique tunnel structures and useful properties. Novel methods have been developed to synthesize novel nanoscale octahedral molecular sieve manganese oxides (OMS) and metal-substituted OMS materials in order to modify their physical and chemical properties and to improve their catalytic applications. Different synthetic routes were investigated to find better, faster, and cheaper pathways to produce nanoscale or metal-substituted OMS materials. In the synthetic study of nanosize OMS materials, a combination of sol-gel synthesis and hydrothermal reaction was used to prepare pure crystalline nanofibrous todorokite-type (OMS-1) and cryptomelane-typed (OMS-2) manganese oxides using four alkali cations (Li+, K+, Na +, Rb+) and NH4+ cations. In the synthesis study of nanoscale and metal-substituted OMS materials, a combination of sol-gel synthesis and solid-state reaction was used to prepare transition metal-substituted OMS-2 nanorods, nanoneedles, and nanowires. Preparative parameters of syntheses, such as cation templates, heating temperature and time, were investigated in these syntheses of OMS-1 and OMS-2 materials. The catalytic activities of the novel synthetic nanoscale OMS materials has been evaluated on green oxidation of alcohols and toluene and were found to be much higher than their correspondent bulk materials. New applications of bulk manganese oxide molecular sieve and layered materials

  16. A controllable molecular sieve for Na+ and K+ ions.

    PubMed

    Gong, Xiaojing; Li, Jichen; Xu, Ke; Wang, Jianfeng; Yang, Hui

    2010-02-17

    The selective rate of specific ion transport across nanoporous material is critical to biological and nanofluidic systems. Molecular sieves for ions can be achieved by steric and electrical effects. However, the radii of Na(+) and K(+) are quite similar; they both carry a positive charge, making them difficult to separate. Biological ionic channels contain precisely arranged arrays of amino acids that can efficiently recognize and guide the passage of K(+) or Na(+) across the cell membrane. However, the design of inorganic channels with novel recognition mechanisms that control the ionic selectivity remains a challenge. We present here a design for a controllable ion-selective nanopore (molecular sieve) based on a single-walled carbon nanotube with specially arranged carbonyl oxygen atoms modified inside the nanopore, which was inspired by the structure of potassium channels in membrane spanning proteins (e.g., KcsA). Our molecular dynamics simulations show that the remarkable selectivity is attributed to the hydration structure of Na(+) or K(+) confined in the nanochannels, which can be precisely tuned by different patterns of the carbonyl oxygen atoms. The results also suggest that a confined environment plays a dominant role in the selectivity process. These studies provide a better understanding of the mechanism of ionic selectivity in the KcsA channel and possible technical applications in nanotechnology and biotechnology, including serving as a laboratory-in-nanotube for special chemical interactions and as a high-efficiency nanodevice for purification or desalination of sea and brackish water. PMID:20102186

  17. A controllable molecular sieve for Na+ and K+ ions.

    PubMed

    Gong, Xiaojing; Li, Jichen; Xu, Ke; Wang, Jianfeng; Yang, Hui

    2010-02-17

    The selective rate of specific ion transport across nanoporous material is critical to biological and nanofluidic systems. Molecular sieves for ions can be achieved by steric and electrical effects. However, the radii of Na(+) and K(+) are quite similar; they both carry a positive charge, making them difficult to separate. Biological ionic channels contain precisely arranged arrays of amino acids that can efficiently recognize and guide the passage of K(+) or Na(+) across the cell membrane. However, the design of inorganic channels with novel recognition mechanisms that control the ionic selectivity remains a challenge. We present here a design for a controllable ion-selective nanopore (molecular sieve) based on a single-walled carbon nanotube with specially arranged carbonyl oxygen atoms modified inside the nanopore, which was inspired by the structure of potassium channels in membrane spanning proteins (e.g., KcsA). Our molecular dynamics simulations show that the remarkable selectivity is attributed to the hydration structure of Na(+) or K(+) confined in the nanochannels, which can be precisely tuned by different patterns of the carbonyl oxygen atoms. The results also suggest that a confined environment plays a dominant role in the selectivity process. These studies provide a better understanding of the mechanism of ionic selectivity in the KcsA channel and possible technical applications in nanotechnology and biotechnology, including serving as a laboratory-in-nanotube for special chemical interactions and as a high-efficiency nanodevice for purification or desalination of sea and brackish water.

  18. Evaluation of Strontium Selectivity by Sandia Octahedral Molecular Sieves (SOMS).

    SciTech Connect

    Rigali, Mark J.; Stewart, Thomas Austin

    2016-01-01

    Sandia National Laboratories has collaborated with Pleasanton Ridge Research Company (PRRC) to determine whether Sandia Octahedral Molecular Sieves (SOMS) and modified SOMs materials can be synthesized in large batches and produced in granular form. Sandia National Laboratories tested these SOMS and its variants based in aqueous chemical environments for an application-based evaluation of material performance as a sorbent. Testing focused primarily on determining the distribution coefficients (K d ) and chemical selectivity SOMs for alkali earth (Sr) ions in aqueous and dilute seawater solutions. In general the well-crystallized SOMS materials tested exhibited very high K d values (>10 6 ) in distilled water but K d values dropped substantially (%7E10 2 -10 3 ) in the dilute seawater (3%). However, one set of SOMS samples (1.4.2 and 1.4.6) provided by PRRC yielded relatively high K d (approaching 10 4 ) in dilute seawater. Further examination of these samples by scanning electron microscopy (SEM) revealed the presence of at least two phases at least one of which may be accounting for the improved K d values in dilute seawater. Evaluation of Strontium Selectivity by Sandia Octahedral Molecular Sieves (SOMS) January 20, 2016

  19. Method of recovering adsorbed liquid compounds from molecular sieve columns

    DOEpatents

    Burkholder, Harvey R.; Fanslow, Glenn E.

    1983-01-01

    Molecularly adsorbed volatile liquid compounds are recovered from molecular sieve adsorbent columns by directionally applying microwave energy to the bed of the adsorbent to produce a mixed liquid-gas effluent. The gas portion of the effluent generates pressure within the bed to promote the discharge of the effluent from the column bottoms. Preferably the discharged liquid-gas effluent is collected in two to three separate fractions, the second or intermediate fraction having a substantially higher concentration of the desorbed compound than the first or third fractions. The desorption does not need to be assisted by passing a carrier gas through the bed or by applying reduced pressure to the outlet from the bed.

  20. Method of recovering adsorbed liquid compounds from molecular sieve columns

    DOEpatents

    Burkholder, H.R.; Fanslow, G.E.

    1983-12-20

    Molecularly adsorbed volatile liquid compounds are recovered from molecular sieve adsorbent columns by directionally applying microwave energy to the bed of the adsorbent to produce a mixed liquid-gas effluent. The gas portion of the effluent generates pressure within the bed to promote the discharge of the effluent from the column bottoms. Preferably the discharged liquid-gas effluent is collected in two to three separate fractions, the second or intermediate fraction having a substantially higher concentration of the desorbed compound than the first or third fractions. The desorption does not need to be assisted by passing a carrier gas through the bed or by applying reduced pressure to the outlet from the bed. 8 figs.

  1. Transformation of metal-organic frameworks for molecular sieving membranes.

    PubMed

    Li, Wanbin; Zhang, Yufan; Zhang, Congyang; Meng, Qin; Xu, Zehai; Su, Pengcheng; Li, Qingbiao; Shen, Chong; Fan, Zheng; Qin, Lei; Zhang, Guoliang

    2016-04-19

    The development of simple, versatile strategies for the synthesis of metal-organic framework (MOF)-derived membranes are of increasing scientific interest, but challenges exist in understanding suitable fabrication mechanisms. Here we report a route for the complete transformation of a series of MOF membranes and particles, based on multivalent cation substitution. Through our approach, the effective pore size can be reduced through the immobilization of metal salt residues in the cavities, and appropriate MOF crystal facets can be exposed, to achieve competitive molecular sieving capabilities. The method can also be used more generally for the synthesis of a variety of MOF membranes and particles. Importantly, we design and synthesize promising MOF membranes candidates that are hard to achieve through conventional methods. For example, our CuBTC/MIL-100 membrane exhibits 89, 171, 241 and 336 times higher H2 permeance than that of CO2, O2, N2 and CH4, respectively.

  2. Transformation of metal-organic frameworks for molecular sieving membranes

    NASA Astrophysics Data System (ADS)

    Li, Wanbin; Zhang, Yufan; Zhang, Congyang; Meng, Qin; Xu, Zehai; Su, Pengcheng; Li, Qingbiao; Shen, Chong; Fan, Zheng; Qin, Lei; Zhang, Guoliang

    2016-04-01

    The development of simple, versatile strategies for the synthesis of metal-organic framework (MOF)-derived membranes are of increasing scientific interest, but challenges exist in understanding suitable fabrication mechanisms. Here we report a route for the complete transformation of a series of MOF membranes and particles, based on multivalent cation substitution. Through our approach, the effective pore size can be reduced through the immobilization of metal salt residues in the cavities, and appropriate MOF crystal facets can be exposed, to achieve competitive molecular sieving capabilities. The method can also be used more generally for the synthesis of a variety of MOF membranes and particles. Importantly, we design and synthesize promising MOF membranes candidates that are hard to achieve through conventional methods. For example, our CuBTC/MIL-100 membrane exhibits 89, 171, 241 and 336 times higher H2 permeance than that of CO2, O2, N2 and CH4, respectively.

  3. Transformation of metal-organic frameworks for molecular sieving membranes

    PubMed Central

    Li, Wanbin; Zhang, Yufan; Zhang, Congyang; Meng, Qin; Xu, Zehai; Su, Pengcheng; Li, Qingbiao; Shen, Chong; Fan, Zheng; Qin, Lei; Zhang, Guoliang

    2016-01-01

    The development of simple, versatile strategies for the synthesis of metal-organic framework (MOF)-derived membranes are of increasing scientific interest, but challenges exist in understanding suitable fabrication mechanisms. Here we report a route for the complete transformation of a series of MOF membranes and particles, based on multivalent cation substitution. Through our approach, the effective pore size can be reduced through the immobilization of metal salt residues in the cavities, and appropriate MOF crystal facets can be exposed, to achieve competitive molecular sieving capabilities. The method can also be used more generally for the synthesis of a variety of MOF membranes and particles. Importantly, we design and synthesize promising MOF membranes candidates that are hard to achieve through conventional methods. For example, our CuBTC/MIL-100 membrane exhibits 89, 171, 241 and 336 times higher H2 permeance than that of CO2, O2, N2 and CH4, respectively. PMID:27090597

  4. Investigation of Y/SBA Composite Molecular Sieves Morphology Control and Catalytic Performance for n-Pentane Aromatization

    NASA Astrophysics Data System (ADS)

    Shi, Chun-Wei; Wu, Wen-Yuan; Li, Shuai; Bian, Xue; Zhao, Shan-Lin; Pei, Ming-Yuan

    2016-03-01

    Using Y molecular sieve as the core, Y/SBA-15 composite molecular sieves were prepared by different crystallization methods in the paper. The growth process and morphologies of the composite molecular sieves were controlled by adjusting the synthesis factors. The structures and acidity of two kinds of composite molecular sieves were characterized by X-ray diffraction (XRD), N2 adsorption/desorption, transmission electron microscopy (TEM), and NH3-TPD. The catalysis performances of the composite molecular sieves were investigated in the aromatization reaction of n-pentane. The results indicated that the desired core-shell composite molecular sieves were obtained when the crystallization conditions were 36 hours, 100 °C and secondary crystallization. The aromatization results showed that core-shell composite molecular sieves had better selectivity for producing high application value xylenes compared to mixed-crystal composite molecular sieves.

  5. Investigation of Y/SBA Composite Molecular Sieves Morphology Control and Catalytic Performance for n-Pentane Aromatization

    PubMed Central

    Shi, Chun-Wei; Wu, Wen-Yuan; Li, Shuai; Bian, Xue; Zhao, Shan-lin; Pei, Ming-Yuan

    2016-01-01

    Using Y molecular sieve as the core, Y/SBA-15 composite molecular sieves were prepared by different crystallization methods in the paper. The growth process and morphologies of the composite molecular sieves were controlled by adjusting the synthesis factors. The structures and acidity of two kinds of composite molecular sieves were characterized by X-ray diffraction (XRD), N2 adsorption/desorption, transmission electron microscopy (TEM), and NH3-TPD. The catalysis performances of the composite molecular sieves were investigated in the aromatization reaction of n-pentane. The results indicated that the desired core-shell composite molecular sieves were obtained when the crystallization conditions were 36 hours, 100 °C and secondary crystallization. The aromatization results showed that core-shell composite molecular sieves had better selectivity for producing high application value xylenes compared to mixed-crystal composite molecular sieves. PMID:27029526

  6. Practical-scale tests of cryogenic molecular sieve for separating low-concentration hydrogen isotopes from helium

    SciTech Connect

    Willms, R.S.; Taylor, D.J.; Enoeda, Mikio; Okuno, Kenji

    1994-06-01

    Earlier bench-scale work at the Tritium Systems Test Assembly (TSTA) at Los Alamos National Laboratory examined a number of adsorbents for their suitability for separating low-concentration hydrogen (no tritium) from helium. One of the effective adsorbents was Linde 5A molecular sieve. Recently, experiments including tritium were conducted using practical-scale adsorbers. These tests used existing cryogenic molecular sieve beds (CMSB`s) which each contain about 1.6 kg of Linde 5A molecular sieve. They are part of the TSTA integrated tritium processing system. Gas was fed to each CMSB at about 13 SLPM with a nominal composition of 99% He, 0.98% H{sub 2} and 0.02% HT. In all cases, for an extended period of time, the beds allowed no detectable (via Raman spectroscopy) hydrogen isotopes to escape in the bed effluent. Thereafter, the hydrogen isotopes appeared in the bed exit with a relatively sharp breakthrough curve. This work concludes that cryogenic molecular sieve adsorption is an practical and effective means of separating low-concentration hydrogen isotopes from a helium carrier.

  7. Use of Carbon Fiber Composite Molecular Sieves for Air Separation

    SciTech Connect

    Baker, Frederick S; Contescu, Cristian I; Gallego, Nidia C; Burchell, Timothy D

    2005-09-01

    A novel adsorbent material, 'carbon fiber composite molecular sieve' (CFCMS), has been developed by the Oak Ridge National Laboratory. Its features include high surface area, large pore volume, and a rigid, permeable carbon structure that exhibits significant electrical conductivity. The unique combination of high adsorptive capacity, permeability, good mechanical properties, and electrical conductivity represents an enabling technology for the development of novel gas separation and purification systems. In this context, it is proposed that a fast-cycle air separation process that exploits a kinetic separation of oxygen and nitrogen should be possible using a CFCMS material coupled with electrical swing adsorption (ESA). The adsorption of O{sub 2}, N{sub 2}, and CO{sub 2} on activated carbon fibers was investigated using static and dynamic techniques. Molecular sieving effects in the activated carbon fiber were highlighted by the adsorption of CO{sub 2}, a more sensitive probe molecule for the presence of microporosity in adsorbents. The kinetic studies revealed that O2 was more rapidly adsorbed on the carbon fiber than N{sub 2}, and with higher uptake under equilibrium conditions, providing the fiber contained a high proportion of very narrow micropores. The work indicated that CFCMS is capable of separating O{sub 2} and N{sub 2} from air on the basis of the different diffusion rates of the two molecules in the micropore network of the activated carbon fibers comprising the composite material. In response to recent enquires from several potential users of CFCMS materials, attention has been given to the development of a viable continuous process for the commercial production of CFCMS material. As part of this effort, work was implemented on characterizing the performance of lignin-based activated carbon fiber, a potentially lower cost fiber than the pitch-based fibers used for CFCMS production to date. Similarly, to address engineering issues, measurements were

  8. Isotherms for Water Adsorption on Molecular Sieve 3A: Influence of Cation Composition

    SciTech Connect

    Lin, Ronghong; Ladshaw, Austin; Nan, Yue; Liu, Jiuxu; Yiacoumi, Sotira; Tsouris, Costas; DePaoli, David W.; Tavlarides, Lawrence L.

    2015-06-16

    This study is part of our continuing efforts to address engineering issues related to the removal of tritiated water from off-gases produced in used nuclear fuel reprocessing facilities. In the current study, adsorption equilibrium of water on molecular sieve 3A beads was investigated. Adsorption isotherms for water on the UOP molecular sieve 3A were measured by a continuous-flow adsorption system at 298, 313, 333, and 353 K. Experimental data collected were analyzed by the Generalized Statistical Thermodynamic Adsorption (GSTA) isotherm model. The K+/Na+ molar ratio of this particular type of molecular sieve 3A was ~4:6. Our results showed that the GSTA isotherm model worked very well to describe the equilibrium behavior of water adsorption on molecular sieve 3A. The optimum number of parameters for the current experimental data was determined to be a set of four equilibrium parameters. This result suggests that the adsorbent crystals contain four energetically distinct adsorption sites. In addition, it was found that water adsorption on molecular sieve 3A follows a three-stage adsorption process. This three-stage adsorption process confirmed different water adsorption sites in molecular sieve crystals. In addition, the second adsorption stage is significantly affected by the K+/Na+ molar ratio. In this stage, the equilibrium adsorption capacity at a given water vapor pressure increases as the K+/Na+ molar ratio increases.

  9. Isotherms for Water Adsorption on Molecular Sieve 3A: Influence of Cation Composition

    DOE PAGESBeta

    Lin, Ronghong; Ladshaw, Austin; Nan, Yue; Liu, Jiuxu; Yiacoumi, Sotira; Tsouris, Costas; DePaoli, David W.; Tavlarides, Lawrence L.

    2015-06-16

    This study is part of our continuing efforts to address engineering issues related to the removal of tritiated water from off-gases produced in used nuclear fuel reprocessing facilities. In the current study, adsorption equilibrium of water on molecular sieve 3A beads was investigated. Adsorption isotherms for water on the UOP molecular sieve 3A were measured by a continuous-flow adsorption system at 298, 313, 333, and 353 K. Experimental data collected were analyzed by the Generalized Statistical Thermodynamic Adsorption (GSTA) isotherm model. The K+/Na+ molar ratio of this particular type of molecular sieve 3A was ~4:6. Our results showed that themore » GSTA isotherm model worked very well to describe the equilibrium behavior of water adsorption on molecular sieve 3A. The optimum number of parameters for the current experimental data was determined to be a set of four equilibrium parameters. This result suggests that the adsorbent crystals contain four energetically distinct adsorption sites. In addition, it was found that water adsorption on molecular sieve 3A follows a three-stage adsorption process. This three-stage adsorption process confirmed different water adsorption sites in molecular sieve crystals. In addition, the second adsorption stage is significantly affected by the K+/Na+ molar ratio. In this stage, the equilibrium adsorption capacity at a given water vapor pressure increases as the K+/Na+ molar ratio increases.« less

  10. Synthesis of mesoporous SAPO-34 molecular sieves and their applications in dehydration of butanols and ethanol.

    PubMed

    Jun, Jong Won; Jeon, Jaewoo; Kim, Chul-Ung; Jeong, Kwang-Eun; Jeong, Soon-Yong; Jhung, Sung Hwa

    2013-04-01

    Microporous SAPO-34 molecular sieves were hydrothermally synthesized with microwave irradiation in the presence of tetraethylammonium hydroxide (TEAOH) as a template. SAPO-34 molecular sieves with mesoporosity were also prepared in the presence of carbon black as a hard template. By increasing the content of the carbon black template in the synthesis, the mesopore volume increased. Dehydration of alcohols (butanols and ethanol) was carried out with the synthesized SAPO-34 molecular sieves, and the lifetime of the catalysts for the dehydration reaction increased as the mesoporosity increased. Moreover, the performance of the microporous catalyst synthesized with microwave was better than that of the catalyst obtained with conventional electric heating. The relative performance of the catalytic dehydration may be explained by the mesoporosity and the crystal size. Therefore, it may be concluded that small-sized SAPO-34 molecular sieves with high mesoporosity can be produced efficiently with microwave irradiation in the presence of carbon black template, and the molecular sieves are effective in the stable dehydration of alcohols.

  11. Microscopic Observation of Kinetic Molecular Sieving of Hydrogen Isotopes in a Nanoporous Material

    SciTech Connect

    Nguyen, T. X.; Bhatia, S. K.; Jobic, H.

    2010-08-20

    We report quasielastic neutron scattering studies of H{sub 2}-D{sub 2} diffusion in a carbon molecular sieve, demonstrating remarkable quantum effects, with the heavier isotope diffusing faster below 100 K, confirming our recent predictions. Our transition state theory and molecular dynamics calculations show that while it is critical for this effect to have narrow windows of size comparable to the de Broglie wavelength, high flux requires that the energy barrier be reduced through small cages. Such materials will enable novel processes for kinetic molecular sieving of hydrogen isotopes.

  12. In-situ preparation of functionalized molecular sieve material and a methodology to remove template

    NASA Astrophysics Data System (ADS)

    Yadav, Rekha; Ahmed, Maqsood; Singh, Arvind Kumar; Sakthivel, Ayyamperumal

    2016-03-01

    A series of diaminosilane-functionalized silicoaluminophosphate molecular sieve (SAPO-37) was prepared by in-situ synthesis, and a novel method was developed for the selective removal of structure directing agent (SDA)/template from the functionalized SAPO-37.The complete removal of the SDA was evident according to FT-IR, TGA, 13C MAS-NMR and elemental analysis. The developed method was found to be efficient for removal of template from microporous molecular sieve viz., SAPO-37 and can be applied for other microporous molecular sieves such as SAPO-5, SAPO-40, etc. The powder XRD pattern of the template-removed samples showed a highly crystalline SAPO-37 phase. Argentometric titration revealed that more than 90% of diamine functionality exposed on the surface was accessible for catalytic applications. The resultant materials showed promising activity for ring opening of epoxide with aniline to yield β-amino-alcohol.

  13. The modeling of cobalt ions adsorption on molecular sieves and zeolite AW-300

    NASA Astrophysics Data System (ADS)

    ćiçek, Ekrem; Aras, Erdal; Dede, Bülent; Kılıç, Ahmet

    2013-12-01

    High concentration heavy metals in the environment can cause serious problem on human health. Cobalt is a heavy metal that has a large application in different fields. In the present work, we aimed to investigate the adsorption of the cobalt ions from aqueous solutions on molecular sieves and zeolite AW-300. Molecular sieves and zeolites were activated at 873 K for two hours before the adsorption experiment. UV-Visible spectrometer was used to measure concentrations of cobalt ions. All adsorption experiments were performed according to statistical designs for response surface methodological approach. A response surface analysis was guided to advance understand the interactions between adsorbent dose and initial concentration of cobalt ions. The removal efficiencies of cobalt ions on sorbents were characterized. The results indicated that molecular sieves and zeolite AW-300 can be used to remove cobalt ions from aqueous solutions.

  14. A systematic investigation of the preparation and properties of composite carbon molecular sieves containing inorganic oxides

    NASA Technical Reports Server (NTRS)

    Foley, Henry C.

    1990-01-01

    The objective of this research is to define the methodology for the preparation and characterization of new carbon-based molecular sieves with composite structures. Carbon molecular sieves have found increasing application in the field of separation and purification of gases. These materials are relatively easy to prepare and their surfaces can be modified to some extent. It is expected that by combining inorganic oxides with the carbonaceous structure one can begin to design composite materials with a wider range of possible chemical and physical properties. In this way, the IOM-CMS materials may confer distinct advantages over pure carbon molecular sieves, not just for separation, but also for catalysis. The most recent results in the design and characterization of these IOM-CMS materials are reviewed and summarized. Directions for further research are also presented.

  15. In-situ preparation of functionalized molecular sieve material and a methodology to remove template

    PubMed Central

    Yadav, Rekha; Ahmed, Maqsood; Singh, Arvind Kumar; Sakthivel, Ayyamperumal

    2016-01-01

    A series of diaminosilane-functionalized silicoaluminophosphate molecular sieve (SAPO-37) was prepared by in-situ synthesis, and a novel method was developed for the selective removal of structure directing agent (SDA)/template from the functionalized SAPO-37.The complete removal of the SDA was evident according to FT-IR, TGA, 13C MAS-NMR and elemental analysis. The developed method was found to be efficient for removal of template from microporous molecular sieve viz., SAPO-37 and can be applied for other microporous molecular sieves such as SAPO-5, SAPO-40, etc. The powder XRD pattern of the template-removed samples showed a highly crystalline SAPO-37 phase. Argentometric titration revealed that more than 90% of diamine functionality exposed on the surface was accessible for catalytic applications. The resultant materials showed promising activity for ring opening of epoxide with aniline to yield β-amino-alcohol. PMID:26960707

  16. Update on N2O4 Molecular Sieving with 3A Material at NASA/KSC

    NASA Technical Reports Server (NTRS)

    Davis, Chuck; Dorn, Claudia

    2000-01-01

    During its operational life, the Shuttle Program has experienced numerous failures in the Nitrogen Tetroxide (N2O4) portion of Reaction Control System (RCS), many of which were attributed to iron-nitrate contamination. Since the mid-1980's, N2O4 has been processed through a molecular sieve at the N2O4 manufacturer's facility which results in an iron content typically less than 0.5 parts-per-million-by-weight (ppmw). In February 1995, a Tiger Team was formed to attempt to resolve the iron nitrate problem. Eighteen specific actions were recommended as possibly reducing system failures. Those recommended actions include additional N2O4 molecular sieving at the Shuttle launch site. Testing at NASA White Sands Test Facility (WSTF) determined an alternative molecular sieve material could also reduce the water-equivalent content (free water and HNO3) and thereby further reduce the natural production of iron nitrate in N2O4 while stored in iron-alloy storage tanks. Since April '96, NASA Kennedy Space Center (KSC) has been processing N2O4 through the alternative molecular sieve material prior to delivery to Shuttle launch pad N2O4 storage tanks. A new, much larger capacity molecular sieve unit has also been used. This paper will evaluate the effectiveness of N2O4 molecular sieving on a large-scale basis and attempt to determine if the resultant lower-iron and lower-water content N2O4 maintains this new purity level in pad storage tanks and shuttle flight systems.

  17. Chlorodifluoromethane equilibrium on 13X molecular sieve. Final report, September 1992-March 1993

    SciTech Connect

    Carlile, D.L.; Mahle, J.J.; Buettner, L.C.; Tevault, D.E.; Friday, D.K.

    1994-08-01

    Adsorption phase equilibrium data are required for evaluating any adsorption-based gas separation process. The U.S. Army Edgewood Research, Development and Engineering Center is currently measuring adsorption phase equilibrium data for a variety of chemical warfare agents and their surrogates on adsorbent materials to correlate physical properties to filtration/separation efficiencies of each vapor on each adsorbent. This report details the adsorption phase equilibrium data measured for chlorodifluoromethane (R-22) on 13X Molecular Sieve. The 13X Molecular Sieve is a candidate adsorbent for future military air purification systems employing the pressure-swing adsorption separation process.

  18. Application of 3A molecular sieve layer in dye-sensitized solar cells

    SciTech Connect

    Yan, Yuan; Wang, Jinzhong E-mail: qingjiang.yu@hit.edu.cn; Yu, Qingjiang E-mail: qingjiang.yu@hit.edu.cn; Huang, Yuewu; Chang, Quanhong; Hao, Chunlei; Jiao, Shujie; Gao, Shiyong; Li, Hongtao; Wang, Dongbo

    2014-08-25

    3A molecular sieve layer was used as dehydration and electronic-insulation layer on the TiO{sub 2} electrode of dye-sensitized solar cells. This layer diminished the effect of water in electrolyte efficiently and enhanced the performance of cells. The conversion efficiency increased from 9.58% to 10.2%. The good moisture resistance of cells was attributed to the three-dimensional interconnecting structure of 3A molecular sieve with strong adsorption of water molecule. While the performance enhancement benefited from the suppression of the charge recombination of electronic-insulation layer and scattering effect of large particles.

  19. Development of design information for molecular-sieve type regenerative CO2-removal systems

    NASA Technical Reports Server (NTRS)

    Wright, R. M.; Ruder, J. M.; Dunn, V. B.; Hwang, K. C.

    1973-01-01

    Experimental and analytic studies were conducted with molecular sieve sorbents to provide basic design information, and to develop a system design technique for regenerable CO2-removal systems for manned spacecraft. Single sorbate equilibrium data were obtained over a wide range of conditions for CO2, water, nitrogen, and oxygen on several molecular sieve and silica gel sorbents. The coadsorption of CO2 with water preloads, and with oxygen and nitrogen was experimentally evaluated. Mass-transfer, and some limited heat-transfer performance evaluations were accomplished under representative operating conditions, including the coadsorption of CO2 and water. CO2-removal system performance prediction capability was derived.

  20. CTR Fuel recovery system using regeneration of a molecular sieve drying bed

    DOEpatents

    Folkers, Charles L.

    1981-01-01

    A primary molecular sieve drying bed is regenerated by circulating a hot inert gas through the heated primary bed to desorb water held on the bed. The inert gas plus water vapor is then cooled and passed through an auxiliary molecular sieve bed which adsorbs the water originally desorbed from the primary bed. The main advantage of the regeneration technique is that the partial pressure of water can be reduced to the 10.sup.-9 atm. range. This is significant in certain CTR applications where tritiated water (T.sub.2 O, HTO) must be collected and kept at very low partial pressure.

  1. Molecular sieve generation of aviator's oxygen: Performance of a prototype system under simulated flight conditions.

    PubMed

    Miller, R L; Ikels, K G; Lamb, M J; Boscola, E J; Ferguson, R H

    1980-07-01

    The molecular sieve method of generating an enriched-oxygen breathing gas is one of several candidate onboard oxygen generation (OBOG) systems under joint Army-Navy-Air Force development for application in tactical aircraft. The performance of a nominal two-man-capacity molecular sieve oxygen generation system was characterized under simulated flight conditions. Data are given on the composition of the molecular sieve-generated breathing gas (oxygen, nitrogen, carbon dioxide, and argon) as a function of inlet air pressure, altitude, breathing gas flow rate, and ambient temperature. The maximum oxygen concentration observed was 95%, with the balance argon. At low demand flow rates and certain conditions of pressure and altitude, the argon enrichment factor exceeded that of oxygen giving a maximum argon concentration of 6.6% with the balance oxygen. The structural integrity of the unit was verified by vibration and centrifuge testing. The performance of the molecular sieve unit is discussed in the context of aircraft operating envelopes using both diluter-demand and 100% delivery subsystems. PMID:6774707

  2. Experiments for the Undergraduate Laboratory that Illustrate the Size-Exclusion Properties of Zeolite Molecular Sieves

    ERIC Educational Resources Information Center

    Cooke, Jason; Henderson, Eric J.

    2009-01-01

    Experiments are presented that demonstrate the size-exclusion properties of zeolites and reveal the reason for naming zeolites "molecular sieves". If an IR spectrometer is available, the adsorption or exclusion of alcohols of varying sizes from dichloromethane or chloroform solutions can be readily demonstrated by monitoring changes in the…

  3. Quinidine thiourea-catalyzed enantioselective synthesis of β-nitrophosphonates: Beneficial effects of molecular sieves

    PubMed Central

    Abbaraju, Santhi; Bhanushali, Mayur; Zhao, Cong-Gui

    2011-01-01

    An efficient method for enantioselective synthesis of β-nitrophosphonates via the Michael addition of diphenyl phosphite to nitroalkenes using the readily available quinidine thiourea organocatalyst has been developed. The desired β-nitrophosphonates were obtained in good ee values. Molecular sieves were found to be crucial for achieving high reproducible yields in this reaction. PMID:21921970

  4. Drying R-407C and R-410A refrigerant blends with molecular sieve desiccants

    SciTech Connect

    Cohen, A.P.; Tucker, D.M.

    1998-10-01

    The hydrofluorocarbon (HFC) R-32 (CF{sub 2}H{sub 2}) is a component of refrigerant blends in the 407 and 410 series being tested and commercialized for use as replacements for R-502 and the hydrochlorofluorocarbon (HCFC) R-22. The molecular sieve desiccants used with chlorofluorocarbon (CFC) and HCFC mineral oil systems in the past have achieved high water capacity by excluding the refrigerant and adsorbing only the water. Unfortunately, R-32 is adsorbed on commercial type 3A molecular sieve desiccant products. The result of this adsorption is a loss of water capacity when drying R-32 compared to drying R-22 or R-502 and a reduced level of chemical compatibility of the desiccant with the refrigerant. Some compressor manufacturers are seeking a water concentration as low as 10 mg/kg (ppm[wt]) in the circulating refrigerant of polyolester-lubricated refrigerating equipment using these HFC blends. This paper compares unmodified commercial type 3A molecular sieve desiccants with a recently developed, modified 3A molecular sieve that excludes R-32. The modified 3A has better chemical compatibility with R-32 and high water capacity in liquid R-407C and R-410A. The drying rates of the two desiccants in R-407C and R-410A are similar. Data and test methods are reported on refrigerant adsorption, water capacity, drying rate, and chemical compatibility.

  5. Molecular sieve generation of aviator's oxygen: Performance of a prototype system under simulated flight conditions.

    PubMed

    Miller, R L; Ikels, K G; Lamb, M J; Boscola, E J; Ferguson, R H

    1980-07-01

    The molecular sieve method of generating an enriched-oxygen breathing gas is one of several candidate onboard oxygen generation (OBOG) systems under joint Army-Navy-Air Force development for application in tactical aircraft. The performance of a nominal two-man-capacity molecular sieve oxygen generation system was characterized under simulated flight conditions. Data are given on the composition of the molecular sieve-generated breathing gas (oxygen, nitrogen, carbon dioxide, and argon) as a function of inlet air pressure, altitude, breathing gas flow rate, and ambient temperature. The maximum oxygen concentration observed was 95%, with the balance argon. At low demand flow rates and certain conditions of pressure and altitude, the argon enrichment factor exceeded that of oxygen giving a maximum argon concentration of 6.6% with the balance oxygen. The structural integrity of the unit was verified by vibration and centrifuge testing. The performance of the molecular sieve unit is discussed in the context of aircraft operating envelopes using both diluter-demand and 100% delivery subsystems.

  6. Effect of soil sieving on respiration induced by low-molecular-weight substrates

    NASA Astrophysics Data System (ADS)

    Datta, Rahul; Vranová, Valerie; Pavelka, Marian; Rejšek, Klement; Formánek, Pavel

    2014-03-01

    The mesh size of sieves has a significant impact upon soil disturbance, affecting pore structure, fungal hyphae, proportion of fungi to bacteria, and organic matter fractions. The effects are dependent upon soil type and plant coverage. Sieving through a 2 mm mesh increases mineralization of exogenously supplied carbohydrates and phenolics compared to a 5 mm mesh and the effect is significant (p<0.05), especially in organic horizons, due to increased microbial metabolism and alteration of other soil properties. Finer mesh size particularly increases arabinose, mannose, galactose, ferulic and pthalic acid metabolism, whereas maltose mineralization is less affected. Sieving through a 5 mm mesh size is suggested for all type of experiments where enhanced mineralization of low-molecular-weight organic compounds needs to be minimalized.

  7. Catalyzing the oxidation of sulfamethoxazole by permanganate using molecular sieves supported ruthenium nanoparticles.

    PubMed

    Zhang, Jing; Sun, Bo; Huang, Yuying; Guan, Xiaohong

    2015-12-01

    This study developed a heterogeneous catalytic permanganate oxidation system with three molecular sieves, i.e., nanosized ZSM-5 (ZSM-5A), microsized ZSM-5 (ZSM-5B) and MCM-41, supported ruthenium nanoparticles as catalyst, denoted as Ru/ZSM-5A, Ru/ZSM-5B and Ru/MCM-41, respectively. The presence of 0.5gL(-1) Ru/ZSM-5A, Ru/ZSM-5B and Ru/MCM-41 increased the oxidation rate of sulfamethoxazole (SMX) by permanganate at pH 7.0 by 27-1144 times. The catalytic performance of Ru catalysts toward SMX oxidation by permanganate was strongly dependent on Ru loading on the catalysts. The X-ray absorption near edge structure (XANES) and extended X-ray absorption fine structure (EXAFS) analyses confirmed that Ru catalyst acted as an electron shuttle in catalytic permanganate oxidation process. Ru(III) deposited on the surface of catalysts was oxidized by permanganate to its higher oxidation state Ru(VII), which could work as a co-oxidant with permanganate to decompose SMX and was then reduced to its initial tri-valence. During the successive runs, Ru/ZSM-5A could not maintain its catalytic activity due to the deposition of MnO2, which was the reductive product of permanganate, onto the surface of Ru/ZSM-5A. Thus, the regeneration of partially deactivated Ru catalysts by reductant NH2OH⋅HCl or ascorbic acid was proposed. Ru/ZSM-5A regenerated by NH2OH⋅HCl displayed comparable catalytic ability to its virgin counterpart, while ascorbic acid could not completely remove the deposited MnO2. A trace amount of leaching of Ru into the reaction solution was also observed, which would be ameliorated by improving the preparation conditions in the future study. PMID:26196405

  8. The effects of zeolite molecular sieve based surface treatments on the properties of wool fabrics

    NASA Astrophysics Data System (ADS)

    Carran, Richard S.; Ghosh, Arun; Dyer, Jolon M.

    2013-12-01

    Wool is a natural composite fiber, with keratin and keratin-associated proteins as the key molecular components. The outermost surface of wool fibers comprises a hydrophobic lipid layer that can lead to unsatisfactory processing and properties of fabric products. In this study, molecular sieve 5A, a Na+ and Ca2+ exchanged type A zeolite with a 1:1 Si:Al ratio was integrated onto the surface of wool using 3-mercaptopropyl trimethoxy silane. The resultant surface morphology, hydrophilicity and mechanical performance of the treated wool fabrics were then evaluated. Notably, the surface hydrophilicity of wool was observed to increase dramatically. When wool was treated with a dispersion of 2 wt% acetic acid, 2.5 wt% zeolite and 0.3 wt% or more silane, the water contact angle was observed to decrease from an average value of 148° to 0° over a period of approximately 30 s. Scanning electron microscopic imaging indicated good coverage of the wool surface with zeolite particles, with infrared spectroscopic evaluation indicating strong bonding of the dealuminated zeolite to wool keratins. This application of zeolite showed no adverse effects on the tensile and other mechanical properties of the fabric. This study indicates that zeolite-based treatment is a potentially efficient approach to increasing the surface hydrophilicity and modifying other key surface properties of wool and wool fabrics.

  9. Reverse osmosis molecular differentiation of organic liquids using carbon molecular sieve membranes

    NASA Astrophysics Data System (ADS)

    Koh, Dong-Yeun; McCool, Benjamin A.; Deckman, Harry W.; Lively, Ryan P.

    2016-08-01

    Liquid-phase separations of similarly sized organic molecules using membranes is a major challenge for energy-intensive industrial separation processes. We created free-standing carbon molecular sieve membranes that translate the advantages of reverse osmosis for aqueous separations to the separation of organic liquids. Polymer precursors were cross-linked with a one-pot technique that protected the porous morphology of the membranes from thermally induced structural rearrangement during carbonization. Permeation studies using benzene derivatives whose kinetic diameters differ by less than an angstrom show kinetically selective organic liquid reverse osmosis. Ratios of single-component fluxes for para- and ortho-xylene exceeding 25 were observed and para- and ortho- liquid mixtures were efficiently separated, with an equimolar feed enriched to 81 mole % para-xylene, without phase change and at ambient temperature.

  10. Reverse osmosis molecular differentiation of organic liquids using carbon molecular sieve membranes.

    PubMed

    Koh, Dong-Yeun; McCool, Benjamin A; Deckman, Harry W; Lively, Ryan P

    2016-08-19

    Liquid-phase separations of similarly sized organic molecules using membranes is a major challenge for energy-intensive industrial separation processes. We created free-standing carbon molecular sieve membranes that translate the advantages of reverse osmosis for aqueous separations to the separation of organic liquids. Polymer precursors were cross-linked with a one-pot technique that protected the porous morphology of the membranes from thermally induced structural rearrangement during carbonization. Permeation studies using benzene derivatives whose kinetic diameters differ by less than an angstrom show kinetically selective organic liquid reverse osmosis. Ratios of single-component fluxes for para- and ortho-xylene exceeding 25 were observed and para- and ortho- liquid mixtures were efficiently separated, with an equimolar feed enriched to 81 mole % para-xylene, without phase change and at ambient temperature. PMID:27540170

  11. Difunctional polyisobutylene prepared by polymerization of monomer on molecular sieve

    NASA Technical Reports Server (NTRS)

    Midler, J. A., Jr.

    1970-01-01

    Process yields difunctional isobutylene polymers ranging in molecular weight from 1150 to 3600. These polymers have the potential for copolymerization and cross-linking with other monomers to form elastomeric materials.

  12. [Removal Characteristics of Elemental Mercury by Mn-Ce/molecular Sieve].

    PubMed

    Tan, Zeng-qiang; Niu, Guo-ping; Chen, Xiao-wen; An, Zhen

    2015-06-01

    The impregnation method was used to support molecular sieve with active manganese and cerium components to obtain a composite molecular sieve catalyst. The mercury removal performance of the catalyst was studied with a bench-scale setup. XPS analysis was used to characterize the sample before and after the modification in order to study the changes in the active components of the catalyst prepared. The results showed that the catalyst carrying manganese and cerium components had higher oxidation ability of elemental mercury in the temperature range of 300 degrees C - 450 degrees C, especially at 450 degrees C, the oxidation efficiency of elemental mercury was kept above 80%. The catalyst had more functional groups that were conducive to the oxidation of elemental mercury, and the mercury removal mainly depended on the chemical adsorption. The SO2 and NO in flue gas could inhibit the oxidation of elemental mercury to certain extent. PMID:26387298

  13. Activation of methane by transition metal-substituted aluminophosphate molecular sieves

    DOEpatents

    Iton, Lennox E.; Maroni, Victor A.

    1991-01-01

    Aluminophosphate molecular sieves substituted with cobalt, manganese or iron and having the AlPO.sub.4 -34 or AlPO.sub.4 -5, or related AlPO.sub.4 structure activate methane starting at approximately 350.degree. C. Between 400.degree. and 500.degree. C. and at methane pressures .ltoreq.1 atmosphere the rate of methane conversion increases steadily with typical conversion efficiencies at 500.degree. C. approaching 50% and selectivity to the production of C.sub.2+ hydrocarbons approaching 100%. The activation mechanism is based on reduction of the transition metal(III) form of the molecular sieve to the transition metal(II) form with accompanying oxidative dehydrogenation of the methane. Reoxidation of the - transition metal(II) form to the transition metal(III) form can be done either chemically (e.g., using O.sub.2) or electrochemically.

  14. Evaluation of RTV as a Moldable Matrix When Combined With Molecular Sieve and Organic Hydrogen Getter

    SciTech Connect

    Knight, J. A.

    2011-12-01

    This work was undertaken in an effort to develop a combined RTV 615/3Å molecular sieve/DEB molded component. A molded RTV 615/3Å molecular sieve component is currently in production, and an RTV 615/DEB component was produced in the past. However, all three materials have never before been combined in a single production part, and this is an opportunity to create a new component capable of being molded to shape, performing desiccation, and hydrogen gettering. This analysis looked at weapons system parameters and how they might influence part design. It also looked at material processing and how it related to mixing, activating a dessicant, and hydrogen uptake testing.

  15. A 1-D Model of the 4 Bed Molecular Sieve of the Carbon Dioxide Removal Assembly

    NASA Technical Reports Server (NTRS)

    Coker, Robert; Knox, Jim

    2015-01-01

    Developments to improve system efficiency and reliability for water and carbon dioxide separation systems on crewed vehicles combine sub-scale systems testing and multi-physics simulations. This paper describes the development of COMSOL simulations in support of the Life Support Systems (LSS) project within NASA's Advanced Exploration Systems (AES) program. Specifically, we model the 4 Bed Molecular Sieve (4BMS) of the Carbon Dioxide Removal Assembly (CDRA) operating on the International Space Station (ISS).

  16. MOLECULAR SIEVES AS CATALYSTS FOR METHANOL DEHYDRATION IN THE LPDMEtm PROCESS

    SciTech Connect

    Andrew W. Wang

    2002-04-01

    Several classes of molecular sieves were investigated as methanol dehydration catalysts for the LPDME{trademark} (liquid-phase dimethyl ether) process. Molecular sieves offer a number of attractive features as potential catalysts for the conversion of methanol to DME. These include (1) a wide range of acid strengths, (2) diverse architectures and channel connectivities that provide latitude for steric control, (3) high active site density, (4) well-investigated syntheses and characterization, and (5) commercial availability in some cases. We directed our work in two areas: (1) a general exploration of the catalytic behavior of various classes of molecular sieves in the LPDME{trademark} system and (2) a focused effort to prepare and test zeolites with predominantly Lewis acidity. In our general exploration, we looked at such diverse materials as chabazites, mordenites, pentasils, SAPOs, and ALPOs. Our work with Lewis acidity sought to exploit the structural advantages of zeolites without the interfering effects of deleterious Broensted sites. We used zeolite Ultrastable Y (USY) as our base material because it possesses a high proportion of Lewis acid sites. This work was extended by modifying the USY through ion exchange to try to neutralize residual Broensted acidity.

  17. A Pervaporation Study of Ammonia Solutions Using Molecular Sieve Silica Membranes

    PubMed Central

    Yang, Xing; Fraser, Thomas; Myat, Darli; Smart, Simon; Zhang, Jianhua; Diniz da Costa, João C.; Liubinas, Audra; Duke, Mikel

    2014-01-01

    An innovative concept is proposed to recover ammonia from industrial wastewater using a molecular sieve silica membrane in pervaporation (PV), benchmarked against vacuum membrane distillation (VMD). Cobalt and iron doped molecular sieve silica-based ceramic membranes were evaluated based on the ammonia concentration factor downstream and long-term performance. A modified low-temperature membrane evaluation system was utilized, featuring the ability to capture and measure ammonia in the permeate. It was found that the silica membrane with confirmed molecular sieving features had higher water selectivity over ammonia. This was due to a size selectivity mechanism that favoured water, but blocked ammonia. However, a cobalt doped silica membrane previously treated with high temperature water solutions demonstrated extraordinary preference towards ammonia by achieving up to a 50,000 mg/L ammonia concentration (a reusable concentration level) measured in the permeate when fed with 800 mg/L of ammonia solution. This exceeded the concentration factor expected by the benchmark VMD process by four-fold, suspected to be due to the competitive adsorption of ammonia over water into the silica structure with pores now large enough to accommodate ammonia. However, this membrane showed a gradual decline in selectivity, suspected to be due to the degradation of the silica material/pore structure after several hours of operation. PMID:24957120

  18. Titanium-containing mesoporous molecular sieves for catalytic oxidation of aromatic compounds

    NASA Astrophysics Data System (ADS)

    Tanev, Peter T.; Chibwe, Malama; Pinnavaia, Thomas J.

    1994-03-01

    TITANIUM silicalite is an effective molecular-sieve catalyst for the selective oxidation of alkanes, the hydroxylation of phenol and the epoxidation of alkenes in the presence of H2O2 (refs 1-3). The range of organic compounds that can be oxidized is greatly limited, however, by the relatively small pore size (about 0.6 nm) of the host framework4. Large-pore (mesoporous) silica-based molecular sieves have been prepared recently by Kresge et all5-7 and Kuroda et al 8.; the former used a templating approach in which the formation of an inorganic mesoporous structure is assisted by self-organization of surfactants, and the latter involved topochemical rearrangement of a layered silica precursor. Here we describe the use of the templating approach to synthesize mesoporous silica-based molecular sieves partly substituted with titanium-large-pore analogues of titanium silicalite. We find that these materials show selective catalytic activity towards the oxidation of 2,6-ditert-butyl phenol to the corresponding quinone and the conversion of benzene to phenol.

  19. Synthesis and characterization of a new microporous cesium silicotitanate (SNL-B) molecular sieve

    SciTech Connect

    NYMAN,MAY D.; GU,B.X.; WANG,L.M.; EWING,R.C.; NENOFF,TINA M.

    2000-03-20

    Ongoing hydrothermal Cs-Ti-Si-O-H{sub 2}O phase investigations has produced several new ternary phases including a novel microporous Cs-silicotitanate molecular sieve, SNL-B with the approximate formula of Cs{sub 3}TiSi{sub 3}O{sub 9.5}{center_dot}3H{sub 2}O. SNL-B is only the second molecular sieve Cs-silicotitanate phase reported to have been synthesized by hydrothermal methods. Crystallites are very small (0.1 x 2 microns) with a blade-like morphology. SNL-B is confirmed to be a 3-dimensional molecular sieve by a variety of characterization techniques (N{sub 2} adsorption, ion exchange, water adsorption/desorption, solid state CP-MAS NMR). SNL-B is able to desorb and adsorb water from its pores while retaining its crystal structure and exchanges Cs cations readily. Additional techniques were used to describe fundamental properties (powder X-ray diffraction, FTIR, {sup 29}Si and {sup 133}/Cs MAS NMR, DTA, SEM/EDS, ion selectivity, and radiation stability). The phase relationships of metastable SNL-B to other hydrothermally synthesized Cs-Ti-Si-O-H{sub 2}O phases are discussed, particularly its relationship to a Cs-silicotitanate analogue of pharmacosiderite, and a novel condensed phase, a polymorph of Cs{sub 2}TiSi{sub 6}O{sub 15}(SNL-A).

  20. Praseodymium incorporated AIPO-5 molecular sieves for aerobic oxidation of ethylbenzene.

    PubMed

    Sundaravel, B; Babu, C M; Palanisamy, B; Palanichamy, M; Shanthi, K; Murugesan, V

    2013-04-01

    PrAlPO-5 with (Al + P)/Pr ratios of 25, 50, 75 and 100 molecular sieves were successfully synthesized by hydrothermal method. These molecular sieves were characterised using XPS, TPD-NH3, ex-situ pyridine adsorbed IR, TPR, TGA, 27Al and 31P MAS-NMR and ESR studies. The incorporation of praseodymium in the framework of AlPO-5 was confirmed by XRD, DRS UV-vis and 27Al and 31P MAS-NMR analysis. ESR spectrum showed the presence of adsorbed oxygen. The nature and strength of acid sites were identified by ex-situ pyridine adsorbed IR and TPD-NH3. The BET surface area was found to be in the range of 238-272 m2 g(-1). The catalytic activity of the molecular sieves was tested for the liquid phase aerobic oxidation of ethylbenzene. Acetophenone was found to be the major product with more than 90% ethylbenzene conversion. ICP-OES analysis revealed the presence of praseodymium intact in the framework of AlPO-5 up to five cycles.

  1. A pervaporation study of ammonia solutions using molecular sieve silica membranes.

    PubMed

    Yang, Xing; Fraser, Thomas; Myat, Darli; Smart, Simon; Zhang, Jianhua; Diniz da Costa, João C; Liubinas, Audra; Duke, Mikel

    2014-01-01

    An innovative concept is proposed to recover ammonia from industrial wastewater using a molecular sieve silica membrane in pervaporation (PV), benchmarked against vacuum membrane distillation (VMD). Cobalt and iron doped molecular sieve silica-based ceramic membranes were evaluated based on the ammonia concentration factor downstream and long-term performance. A modified low-temperature membrane evaluation system was utilized, featuring the ability to capture and measure ammonia in the permeate. It was found that the silica membrane with confirmed molecular sieving features had higher water selectivity over ammonia. This was due to a size selectivity mechanism that favoured water, but blocked ammonia. However, a cobalt doped silica membrane previously treated with high temperature water solutions demonstrated extraordinary preference towards ammonia by achieving up to a 50,000 mg/L ammonia concentration (a reusable concentration level) measured in the permeate when fed with 800 mg/L of ammonia solution. This exceeded the concentration factor expected by the benchmark VMD process by four-fold, suspected to be due to the competitive adsorption of ammonia over water into the silica structure with pores now large enough to accommodate ammonia. However, this membrane showed a gradual decline in selectivity, suspected to be due to the degradation of the silica material/pore structure after several hours of operation. PMID:24957120

  2. Synthetic Zeolites and Other Microporous Oxide Molecular Sieves

    NASA Astrophysics Data System (ADS)

    Sherman, John D.

    1999-03-01

    Use of synthetic zeolites and other microporous oxides since 1950 has improved insulated windows, automobile air-conditioning, refrigerators, air brakes on trucks, laundry detergents, etc. Their large internal pore volumes, molecular-size pores, regularity of crystal structures, and the diverse framework chemical compositions allow "tailoring" of structure and properties. Thus, highly active and selective catalysts as well as adsorbents and ion exchangers with high capacities and selectivities were developed. In the petroleum refining and petrochemical industries, zeolites have made possible cheaper and lead-free gasoline, higher performance and lower-cost synthetic fibers and plastics, and many improvements in process efficiency and quality and in performance. Zeolites also help protect the environment by improving energy efficiency, reducing automobile exhaust and other emissions, cleaning up hazardous wastes (including the Three Mile Island nuclear power plant and other radioactive wastes), and, as specially tailored desiccants, facilitating the substitution of new refrigerants for the ozone-depleting chlorofluorocarbons banned by the Montreal Protocol.

  3. Synthetic zeolites and other microporous oxide molecular sieves.

    PubMed

    Sherman, J D

    1999-03-30

    Use of synthetic zeolites and other microporous oxides since 1950 has improved insulated windows, automobile air-conditioning, refrigerators, air brakes on trucks, laundry detergents, etc. Their large internal pore volumes, molecular-size pores, regularity of crystal structures, and the diverse framework chemical compositions allow "tailoring" of structure and properties. Thus, highly active and selective catalysts as well as adsorbents and ion exchangers with high capacities and selectivities were developed. In the petroleum refining and petrochemical industries, zeolites have made possible cheaper and lead-free gasoline, higher performance and lower-cost synthetic fibers and plastics, and many improvements in process efficiency and quality and in performance. Zeolites also help protect the environment by improving energy efficiency, reducing automobile exhaust and other emissions, cleaning up hazardous wastes (including the Three Mile Island nuclear power plant and other radioactive wastes), and, as specially tailored desiccants, facilitating the substitution of new refrigerants for the ozone-depleting chlorofluorocarbons banned by the Montreal Protocol.

  4. Inclusion of polyaniline filaments in zeolite molecular sieves

    SciTech Connect

    Enzel, P.; Bein, T. )

    1989-08-24

    Polyaniline has been synthesized in the channels of mordenite (one-dimensional) and zeolite Y (three-dimensional). Aniline was diffused from hexane solution into dehydrated zeolite pores containing different concentrations of framework hydroxyl groups. Addition of (NH{sub 4}){sub 2}S{sub 2}O{sub 8} to an aqueous suspension of the loaded zeolites afforded intrazeolite polyaniline chains, as demonstrated by FTIR, electronic absorption data, and recovery of the included polymer. Stoichiometric, kinetic, XPS, and microscopic data and the absence of bulk conductivity of the polymer/zeolite powders lead to the conclusion that the polymer is formed inside the host channel system. While the polyaniline chains in mordenite channels appear to be more highly oxidized than in Y zeolite, both systems show spectroscopic features typical of emeraldine base and emeraldine salt polymers. The polyaniline/zeolite hybrids represent a new class of materials containing synthetic conductors encapsulated in crystalline inorganic hosts with channel systems of molecular dimensions.

  5. Synthetic zeolites and other microporous oxide molecular sieves

    PubMed Central

    Sherman, John D.

    1999-01-01

    Use of synthetic zeolites and other microporous oxides since 1950 has improved insulated windows, automobile air-conditioning, refrigerators, air brakes on trucks, laundry detergents, etc. Their large internal pore volumes, molecular-size pores, regularity of crystal structures, and the diverse framework chemical compositions allow “tailoring” of structure and properties. Thus, highly active and selective catalysts as well as adsorbents and ion exchangers with high capacities and selectivities were developed. In the petroleum refining and petrochemical industries, zeolites have made possible cheaper and lead-free gasoline, higher performance and lower-cost synthetic fibers and plastics, and many improvements in process efficiency and quality and in performance. Zeolites also help protect the environment by improving energy efficiency, reducing automobile exhaust and other emissions, cleaning up hazardous wastes (including the Three Mile Island nuclear power plant and other radioactive wastes), and, as specially tailored desiccants, facilitating the substitution of new refrigerants for the ozone-depleting chlorofluorocarbons banned by the Montreal Protocol. PMID:10097059

  6. Growth of oriented molecular sieve crystals on organophosphonate films

    NASA Astrophysics Data System (ADS)

    Feng, S.; Bein, T.

    1994-04-01

    THE successful construction of complex organic/inorganic bio-mimetic systems1-3has demonstrated the great power of supra-molecular pre-organization and templating in controlling crystal growth4. For instance, polar organic surfaces or surface-attached polar groups can induce the formation of thin films of iron oxide5. It would be of great interest, for the design of novel devices such as sensors or catalyst membranes6, to be able to control the growth on surfaces of porous crystals with oriented channels: such channels could, for example, control the access of molecules to the surface of a field-effect transistor in a sensor device. Films and membranes with non-oriented channels have been prepared by depositing or growing zeolite7-12 crystals on metal or metal-oxide supports13-21 in one case21, pre-grown crystals of an aluminophosphate zeolite were oriented by application of an electric field. Here we report the oriented growth of crystals of a zinco-phosphate zeolite on gold surfaces modified with metal phosphonate multilayer films. We attribute the high degree of orientation (>90%) to a strong affinity between the phosphonic acid groups of the phosphate multilayer and the (111) faces of the growing crystals.

  7. Synthetic zeolites and other microporous oxide molecular sieves.

    PubMed

    Sherman, J D

    1999-03-30

    Use of synthetic zeolites and other microporous oxides since 1950 has improved insulated windows, automobile air-conditioning, refrigerators, air brakes on trucks, laundry detergents, etc. Their large internal pore volumes, molecular-size pores, regularity of crystal structures, and the diverse framework chemical compositions allow "tailoring" of structure and properties. Thus, highly active and selective catalysts as well as adsorbents and ion exchangers with high capacities and selectivities were developed. In the petroleum refining and petrochemical industries, zeolites have made possible cheaper and lead-free gasoline, higher performance and lower-cost synthetic fibers and plastics, and many improvements in process efficiency and quality and in performance. Zeolites also help protect the environment by improving energy efficiency, reducing automobile exhaust and other emissions, cleaning up hazardous wastes (including the Three Mile Island nuclear power plant and other radioactive wastes), and, as specially tailored desiccants, facilitating the substitution of new refrigerants for the ozone-depleting chlorofluorocarbons banned by the Montreal Protocol. PMID:10097059

  8. Molecular sieve oxygen generating system: the argon question--a brief review.

    PubMed

    Ikels, K G; Adams, J D

    1979-09-01

    The molecular sieve oxygen generating system (MSOG) is currently being considered as a replacement for liquid and gaseous stores on aircraft for the supply of aviator's breathing oxygen. Incorporation of onboard oxygen generation in aircraft not only increases system safety but also minimizes logistic requirements. However, a unique characteristic of the MSOG is that it concentrates not only oxygen but also argon in the process of removing nitrogen from engine bleed air. Maximum concentrations produced by present systems are in the order of 95% oxygen and 5% argon. These results have precipitated numerous questions relating to the physiological effects of argon in the product breathing gas. This report reviews the current literature concerning argon as a minor constituent (less than 10%) in gas breathing systems and recommends studies prior to human compatibility testing of the molecule sieve oxygen generating systems.

  9. Investigations to improve carbon dioxide control with amine and molecular sieve type sorbers

    NASA Technical Reports Server (NTRS)

    Bertrand, J. F.; Brose, H. F.; Kester, F. L.; Lunde, P. J.

    1972-01-01

    The optimization trends and operating parameters of an integral molecular sieve bed heat exchanger were investigated. The optimum combination of substrate and coating for the HS-B porous polymer was determined based on the CO2 dynamic capacity in the presence of water vapor. Full size HS-B canister performance was evaluated. An Amine CO2 Concentrator utilizing IR-45 sorber material and available Manned Orbiting Laboratory hardware was designed, fabricated and tested for use as an experiment in the NASA 90-day space simulator test of 1970. It supported four men in the simulator for 71 days out of the 90-day test duration.

  10. Synthesis, characterization, and pulsed laser ablation of molecular sieves for thin film applications

    NASA Astrophysics Data System (ADS)

    Munoz, Trinidad, Jr.

    1998-12-01

    Molecular sieves are one class of crystalline low density metal oxides which are made up of one-, two-, and three dimensional pores and/or cages. We have investigated the synthesis and characterization of metal substituted aluminophosphates and all silica molecular sieves for thin film applications. A new copper substituted aluminophosphate, CuAPO-5 has been synthesized and characterized using x-ray powder diffraction, FT-IR spectroscopy and scanning electron microscopy. Electron spin resonance and electron spin echo modulation provided supporting evidence of framework incorporation of Cu(II) ions. Thus, an exciting addition has been added to the family of metal substituted aluminophosphates where substitution of the metal has been demonstrated as framework species. Also presented here is the synthesis and characterization of an iron substituted aluminophosphate, FeAPO-5, and an all silica zeolite, UTD-1 for thin film applications. Pulsed laser ablation has been employed as the technique to generate thin films. Here an excimer laser (KrFsp*, 248 nm) was used to deposit the molecular sieves on a variety of substrates including polished silicon, titanium nitride, and porous stainless steel disks. The crystallinity of the deposited films was enhanced by a post hydrothermal treatment. A vapor phase treatment of the laser deposited FeAPO-5 films has been shown to increase the crystallinity of the film without increasing film thickness. Thin films of the FeAPO-5 molecular sieves were subsequently used as the dielectric phase in capacitive type chemical sensors. The capacitance change of the FeAPO-5 devices to the relative moisture makes them potential humidity sensors. The all silica zeolite UTD-1 thin films were deposited on polished silicon and porous supports. A brief post hydrothermal treatment of the laser deposited films deposited on polished silicon and porous metal supports resulted in oriented film growth lending these films to applications in gas separations

  11. Ultrahigh CO2 adsorption capacity on carbon molecular sieves at room temperature.

    PubMed

    Silvestre-Albero, Joaquín; Wahby, Anass; Sepúlveda-Escribano, Antonio; Martínez-Escandell, Manuel; Kaneko, Katsumi; Rodríguez-Reinoso, Francisco

    2011-06-28

    Although metal-organic framework (MOF) materials have been postulated as superior to any other sorbent for CO(2) adsorption at room temperature, here we prove that the appropriate selection of the raw material and the synthesis conditions allows the preparation of carbon molecular sieves (CMSs) with adsorption capacity, on a volumetric basis, highly exceeding those reported in the literature for MOFs. Furthermore, the excellent sorption properties of CMSs over the whole pressure range (up to 50 bar) are fully reversible after different adsorption/desorption cycles.

  12. Catalytic Reforming of Lignin-Derived Bio-Oil Over a Nanoporous Molecular Sieve Silicoaluminophosphate-11.

    PubMed

    Park, Y K; Kang, Hyeon Koo; Jang, Hansaem; Suh, Dong Jin; Park, Sung Hoon

    2016-05-01

    Catalytic pyrolysis of lignin, a major constituent of biomass, was performed. A nanoporous molecular sieve silicoaluminophosphate-11 (SAPO-11) was selected as catalyst. Thermogravimetric analysis showed that 500 degrees C was the optimal pyrolysis temperature. Pyrolyzer-gas chromatography/mass spectroscopy was used to investigate the pyrolysis product distribution. Production of phenolics, the dominant product from the pyrolysis of lignin, was promoted by the increase in the catalyst dose. In particular, low-molecular-mass phenolics were produced more over SAPO-11, while high-molecular-mass phenolics and double-bond-containing phenolics were produced less. The fraction of aromatic compounds, including benzene, toluene, xylene, and ethylbenzene, was also increased by catalytic reforming. The catalytic effects were more pronounced when the catalyst/biomass ratio was increased. The enhanced production of aromatic compounds by an acidic catalyst obtained in this study is in good agreement with the results of previous studies.

  13. Catalytic Reforming of Lignin-Derived Bio-Oil Over a Nanoporous Molecular Sieve Silicoaluminophosphate-11.

    PubMed

    Park, Y K; Kang, Hyeon Koo; Jang, Hansaem; Suh, Dong Jin; Park, Sung Hoon

    2016-05-01

    Catalytic pyrolysis of lignin, a major constituent of biomass, was performed. A nanoporous molecular sieve silicoaluminophosphate-11 (SAPO-11) was selected as catalyst. Thermogravimetric analysis showed that 500 degrees C was the optimal pyrolysis temperature. Pyrolyzer-gas chromatography/mass spectroscopy was used to investigate the pyrolysis product distribution. Production of phenolics, the dominant product from the pyrolysis of lignin, was promoted by the increase in the catalyst dose. In particular, low-molecular-mass phenolics were produced more over SAPO-11, while high-molecular-mass phenolics and double-bond-containing phenolics were produced less. The fraction of aromatic compounds, including benzene, toluene, xylene, and ethylbenzene, was also increased by catalytic reforming. The catalytic effects were more pronounced when the catalyst/biomass ratio was increased. The enhanced production of aromatic compounds by an acidic catalyst obtained in this study is in good agreement with the results of previous studies. PMID:27483769

  14. Hydroxylation of phenol over MeAPO molecular sieves synthesized by vapor phase transport

    NASA Astrophysics Data System (ADS)

    Shao, Hui; Chen, Jingjing; Chen, Xia; Leng, Yixin; Zhong, Jing

    2016-07-01

    In this study, MeAPO-25 (Me = Fe, Cu, Mn) molecular sieves were first synthesized by a vapor phase transport method using tetramethyl guanidine as the template and applied to hydroxylation of phenol. The zeolites were characterized by XRD, SEM, FT-IR, and DR UV-Vis. As a result, MeAPO-21 and MeAPO-15 were synthesized by changing the Me/Al ratio. UV-Visible diffuse reflectance study suggested incorporation of heteroatoms into the framework and FT-IR study also supported these data. Effects of heteroatoms, contents of Me in MeAPO-25, reaction temperature, phenol/H2O2 mole ratios, reaction time and concentration of catalyst on the conversion of phenol, as well as on the selectivity were studied. FeAPO-25 exhibited a high catalytic activity at the mole ratio of FeO and Al2O3 equal to 0.1 in the synthesis gel, giving the phenol conversion of 88.75% and diphenols selectivity of 66.23% at 60°C within 3 h [ n(phenol)/ n(H2O2) = 0.75, m(FeAPO-25)/ m(phenol) = 7.5%]. Experimental results indicated that the FeAPO-25 molecular sieve was a fairly promising candidate for the application in hydroxylation of phenol.

  15. Zeolite molecular sieves have dramatic acid-base effects on enzymes in nonaqueous media.

    PubMed

    Fontes, Nuno; Partridge, Johann; Halling, Peter J; Barreiros, Susana

    2002-02-01

    Zeolite molecular sieves very commonly are used as in situ drying agents in reaction mixtures of enzymes in nonaqueous media. They often affect enzyme behavior, and this has been interpreted in terms of altered hydration. Here, we show that zeolites can also have dramatic acid-base effects on enzymes in low water media, resulting from their cation-exchange ability. Initial rates of transesterification catalyzed by cross-linked crystals of subtilisin were compared in supercritical ethane, hexane, and acetonitrile with water activity fixed by pre-equilibration. Addition of zeolite NaA (4 A powder) still caused remarkable rate enhancements (up to 20-fold), despite the separate control of hydration. In the presence of excess of an alternative solid-state acid-base buffer, however, zeolite addition had no effect. The more commonly used Merck molecular sieves (type 3 A beads) had similar but somewhat smaller effects. All zeolites have ion-exchange ability and can exchange H+ for cations such as Na+ and K+. These exchanges will tend to affect the protonation state of acidic groups in the protein and, hence, enzymatic activity. Zeolites pre-equilibrated in aqueous suspensions of varying pH-pNa gave very different enzyme activities. Their differing basicities were demonstrated directly by equilibration with an indicator dissolved in toluene. The potential of zeolites as acid-base buffers for low-water media is discussed, and their ability to overcome pH memory is demonstrated.

  16. Redox chemistry of gaseous reactants inside photoexcited FeAlPO{sub 4} molecular sieve

    SciTech Connect

    Ulagappan, N.; Frei, H.

    2000-01-27

    The reactivity of ligand-to-metal charge transfer excited Fe centers of FeAlPO{sub 4}-5 molecular sieve at the gas-micropore interface has been probed by in situ FT-IR spectroscopy. Laser light in the region 350--430 nm was used to excite the metal centers, and reaction was induced between methanol or 2-propanol and O{sub 2}. Acetone and H{sub 2}O are the observed products of the 2-propanol + O{sub 2} system, while the reaction of methanol with O{sub 2} yields formic acid, methyl formate, and H{sub 2}O as final products. These originate from secondary thermal reaction of initially produced formaldehyde and hydrogen peroxide. The primary step of the proposed mechanism involves one-electron reduction of O{sub 2} by transient Fe{sup +II} under concurrent donation of an electron to be hole of framework oxygen by the alcohol molecule. The efficient reaction suggests that the photoreduced Fe center of the molecular sieve has a substantially stronger reducing power than the conduction band electrons of dense-phase Fe{sub 2}O{sub 3} semiconductor particles.

  17. Molecular sieve/sulfonated poly(ether ketone ether sulfone) composite membrane as proton exchange membrane

    NASA Astrophysics Data System (ADS)

    Changkhamchom, Sairung; Sirivat, Anuvat

    2012-02-01

    A proton exchange membrane (PEM) is an electrolyte membrane used in both polymer electrolyte membrane fuel cells (PEMFC) and direct methanol fuel cells (DMFCs). Currently, PEMs typically used for PEMFCs are mainly the commercially available Nafion^ membranes, which is high cost and loss of proton conductivity at elevated temperature. In this work, the Sulfonated poly(ether ketone ether sulfone), (S-PEKES), was synthesized by the nucleophilic aromatic substitution polycondensation between bisphenol S and 4,4'-dichlorobenzophenone, and followed by the sulfonation reaction with concentrated sulfuric acid. The molecular sieve was added in the S-PEKES matrix at various ratios to form composite membranes to be the candidate for PEM. Properties of both pure sulfonated polymer and composite membranes were compared with the commercial Nafion^ 117 membrane from Dupont. S-PEKES membranes cast from these materials were evaluated as a polymer electrolyte membrane for direct methanol fuel cells. The main properties investigated were the proton conductivity, methanol permeability, thermal, chemical, oxidative, and mechanical stabilities by using a LCR meter, Gas Chromatography, Thermogravimetric Analysis, Fourier Transform Infrared Spectroscopy, Fenton's reagent, and Universal Testing Machine. The addition of the molecular sieve helped to increase both the proton conductivity and the methanol stability. These composite membranes are shown as to be potential candidates for use as a Proton Exchange Membrane (PEM).

  18. A portable molecular-sieve-based CO2 sampling system for radiocarbon measurements

    NASA Astrophysics Data System (ADS)

    Palonen, V.

    2015-12-01

    We have developed a field-capable sampling system for the collection of CO2 samples for radiocarbon-concentration measurements. Most target systems in environmental research are limited in volume and CO2 concentration, making conventional flask sampling hard or impossible for radiocarbon studies. The present system captures the CO2 selectively to cartridges containing 13X molecular sieve material. The sampling does not introduce significant under-pressures or significant losses of moisture to the target system, making it suitable for most environmental targets. The system also incorporates a significantly larger sieve container for the removal of CO2 from chambers prior to the CO2 build-up phase and sampling. In addition, both the CO2 and H2O content of the sample gas are measured continuously. This enables in situ estimation of the amount of collected CO2 and the determination of CO2 flux to a chamber. The portable sampling system is described in detail and tests for the reliability of the method are presented.

  19. A portable molecular-sieve-based CO{sub 2} sampling system for radiocarbon measurements

    SciTech Connect

    Palonen, V.

    2015-12-15

    We have developed a field-capable sampling system for the collection of CO{sub 2} samples for radiocarbon-concentration measurements. Most target systems in environmental research are limited in volume and CO{sub 2} concentration, making conventional flask sampling hard or impossible for radiocarbon studies. The present system captures the CO{sub 2} selectively to cartridges containing 13X molecular sieve material. The sampling does not introduce significant under-pressures or significant losses of moisture to the target system, making it suitable for most environmental targets. The system also incorporates a significantly larger sieve container for the removal of CO{sub 2} from chambers prior to the CO{sub 2} build-up phase and sampling. In addition, both the CO{sub 2} and H{sub 2}O content of the sample gas are measured continuously. This enables in situ estimation of the amount of collected CO{sub 2} and the determination of CO{sub 2} flux to a chamber. The portable sampling system is described in detail and tests for the reliability of the method are presented.

  20. A portable molecular-sieve-based CO2 sampling system for radiocarbon measurements.

    PubMed

    Palonen, V

    2015-12-01

    We have developed a field-capable sampling system for the collection of CO2 samples for radiocarbon-concentration measurements. Most target systems in environmental research are limited in volume and CO2 concentration, making conventional flask sampling hard or impossible for radiocarbon studies. The present system captures the CO2 selectively to cartridges containing 13X molecular sieve material. The sampling does not introduce significant under-pressures or significant losses of moisture to the target system, making it suitable for most environmental targets. The system also incorporates a significantly larger sieve container for the removal of CO2 from chambers prior to the CO2 build-up phase and sampling. In addition, both the CO2 and H2O content of the sample gas are measured continuously. This enables in situ estimation of the amount of collected CO2 and the determination of CO2 flux to a chamber. The portable sampling system is described in detail and tests for the reliability of the method are presented.

  1. Synthesis of MCM-41 molecular sieves in the presence of dialkyl dimethyl ammonium salts

    SciTech Connect

    Karra, V.R.; Sayari, A.

    1995-12-01

    In the synthesis of MCM-41 mesoporous molecular sieves the chain length of the surfactant template plays a major role in determining the pore dimensions of the resulting material. The effect of the bulkiness of quaternary ammonium template on the pore size of mesoporous silicates has been studied using various dialkyl dimethyl ammonium bromide salts. These templates were prepared by refluxing long chain N,N-dimethyl alkyl amines and bromo alkanes for 24 h. The obtained silicates were characterized by various techniques including XRD, nitrogen and benzene adsorption, FTIR, {sup 29}Si MAS NMR and electron microscopy. The relationship between the length of both alkyl groups and the pore size of the material will be presented.

  2. Mesoporous Molecular Sieves Based Catalysts for Olefin Metathesis and Metathesis Polymerization

    NASA Astrophysics Data System (ADS)

    Balcar, Hynek; Čejka, Jiří

    Heterogeneous catalysts for olefin metathesis using different types of (i) siliceous mesoporous molecular sieves, and (ii) organized mesoporous alumina as supports are reported. The catalysts were prepared either by spreading of transition metal oxidic phase on the support surface or by immobilizing transition metal compounds (mostly organometallic) on the support. The activity of these catalysts in various types of metathesis reactions (i.e. alkene and diene metathesis, metathesis of unsaturated esters and ethers, RCM, ROMP and metathesis polymerization of alkynes) was described. The main advantages of these catalysts consist generally in their high activity and selectivity, easy separation of catalysts from reaction products and the preparation of products free of catalyst residue. The examples of pore size influence on the selectivity in metathesis reactions are also given.

  3. Inorganic fluoride uptake as a measure of relative compatibility of molecular sieve desiccants with fluorocarbon refrigerants

    SciTech Connect

    Cohen, A.P.; Blackwell, C.S.

    1995-12-31

    The fluoride content of molecular sieve desiccants after exposure to R-32 in compatibility tests indicates the extent of the reaction of refrigerant with desiccant. The objective is to determine this fluoride content in a way that reports fluorine that has reacted with the desiccant, not fluorine that is present as adsorbed refrigerant. A conditioning procedure is described to remove adsorbed refrigerant by displacement with water vapor. The efficacy of this procedure is substantiated by {sup 19}F NMR spectroscopy. The conditioned desiccant undergoes pyrohydrolysis at a high temperature (975 C, 1787 F) to remove reacted fluorine as HF. Fluoride is determined in the resulting condensate using an ion-selective electrode. The ability of this technique to report accurate fluoride values is confirmed with standard reference materials.

  4. Ionothermal synthesis process for aluminophosphate molecular sieves in the mixed water/ionic liquid system.

    PubMed

    Zhao, Zhenchao; Zhang, Weiping; Xu, Renshun; Han, Xiuwen; Tian, Zhijian; Bao, Xinhe

    2012-01-21

    The synthesis process of aluminophosphate AlPO(4)-11 molecular sieve in the mixed water/1-butyl- 3-methylimidazolium bromide ([bmim]Br) ionic liquid was investigated by XRD, multinuclear solid-state NMR, scanning electron microscopy (SEM) and X-ray energy dispersive spectroscopy (EDS). It was observed that a tablet phase, named SIZ-2, was formed at the early stage of crystallization. During crystallization metastable SIZ-2 with an incompletely condensed framework phosphorus disappeared gradually, and the phosphorous species became fully condensed through hydroxyl reaction with tetrahedral aluminum to form thermodynamically stable AlPO(4)-11 in the final product. It was found that [bmim]Br, acting as the structure-directing agent, was occluded into the AlPO(4)-11 channel.

  5. Production of carbon molecular sieves from Illinois coal. Technical report, March 1, 1994--May 31, 1994

    SciTech Connect

    Lizzio, A.A.; Rostam-Abadi, M.; Feizoulof, C.A.; Vyas, S.N.

    1994-09-01

    Carbon molecular sieves (CMS) have become an increasingly important class of adsorbents for use in gas separation and recovery processes. The overall objective of this project is to determine whether Illinois coal is a suitable feedstock for the production of CMS and to evaluate the potential application of the products in commercial gas separation processes. The full potential of these materials in commercial gas separations has yet to be realized. In Phase II, the optimal char preparation conditions determined in Phase I are being applied to production of larger quantities of CMS in a 2 in. ID batch fluidized-bed reactor (FBR) and a 4 in. ID continuous rotary tube kiln (RTK). In the previous reporting period, an invention disclosure describing a novel CMS preparation technique (oxygen deposition) was prepared and submitted to Research Corporation Technologies for evaluation. During this reporting period, work continued on the development of the oxygen deposition process. Carbon deposition as a means to narrow pore size was also investigated. Pound quantities of CMS were prepared from IBC-102 coal in the TRK. A meeting was arranged between the ISGS and Carbo Tech Industieservice GmbH, one of two companies in the world that produce CMS from coal, to discuss possible shipment of Illinois coal to Germany for CMS production. A secrecy agreement between the ISGS and Carbo Tech is in preparation. Several large scale char production runs using Industry Mine coal were conducted in an 18 in. ID batch and 8 in. ID continuous RTK at Allis Mineral Systems, Milwaukee, WI. The molecular sieve properties of the chars have yet to be determined.

  6. Self-Assembly and Dynamics of Organic 2D Molecular Sieves: Ab Initio and Molecular Dynamics Studies

    NASA Astrophysics Data System (ADS)

    St. John, Alexander; Wexler, Carlos

    2015-03-01

    Spontaneous molecular self-assembly is a promising route for bottom-up manufacturing of two-dimensional (2D) nanostructures with specific topologies on atomically flat surfaces. Of particular interest is the possibility of selective lock-and-key interaction of guest molecules inside cavities formed by complex self-assembled host structures. Our host structure is a monolayer consisting of interdigitated 1,3,5-tristyrylbenzene substituted by alkoxy peripheral chains containing n = 6, 8, 10, 12, or 14 carbon atoms (TSB3,5-C n) deposited on a highly ordered pyrolytic graphite (HOPG) surface. Using ab initio methods from quantum chemistry and molecular dynamics simulations, we construct and analyze the structure and functionality of the TSB3,5-C n monolayer as a molecular sieve. Supported by ACS-PRF 52696-ND5.

  7. Spontaneous liquid-gas imbibition for characterization of carbon molecular sieves.

    PubMed

    Su, Yanmin; Xu, Shaoping; Wang, Jifeng; Xiao, Ronglin

    2012-07-01

    Spontaneous liquid-gas imbibition at 293.2K and 0.1 MPa was conducted to assess the micropore size and size-exclusion property of carbon molecular sieves (CMS). The CMS were firstly saturated with N(2) and then immersed into water. The volume of gas recovered by the water imbibition was measured and applied to evaluate the density of the N(2) adsorbed in the CMS. The micropore size of the CMS was determined by comparing the N(2) density from the water-N(2) imbibition with that calculated by grand canonical simulation. The micropore size evaluated by the liquid-gas imbibition coincides with that obtained by N(2) adsorption at ambient temperature. The size-exclusion property of the CMS was estimated through comparing the N(2) recovery by imbibition of liquids with increasing molecular dimensions, that is, water, benzene, and cyclohexane. The amount of N(2) recovered from benzene imbibition is dramatically less than that from the water imbibition, showing that the dominated micropore size of the CMS is smaller than 0.37 nm. Furthermore, the effect of chemical vapor deposition treatment on the porous texture of the CMS was revealed by the liquid-gas imbibition.

  8. Degradation of antibiotic amoxicillin using 1 x 1 molecular sieve-structured manganese oxide.

    PubMed

    Kuan, Wen-Hui; Hu, Ching-Yao; Liu, Bin-Sheng; Tzou, Yu-Min

    2013-01-01

    The kinetics and mechanism ofamoxicillin (AMO) degradation using a 1 x 1 molecular sieve-structured manganese oxide (MnO2) was studied. The presence of the buffer solution (i.e., NaHCO3, NaH2PO4 and KH2PO4) diminished AMO binding to MnO2, thus reducing AMO degradation in the pretest; therefore, all other experiments in this study were conducted without the addition of a buffer. Third-order rate constants, second-order on AMO and first-order on MnO2 increased with elevating pH level (2.81-7.23) from 0.54 to 9.17 M(-2) s(-1), and it decreased to 4.27 M(-2) s(-1) at pH 8.53 beyond the pk(a2) of AMO (7.3). The dissolution of the MnO2 suspension with and without AMO exhibited a similar trend; that is, Mn2+ concentration increased with decreasing pH. However, the dissolution of MnO2 with AMO was greater than that without AMO, except for the reaction occurring at pH 8.53, partially indicating that MnO2 acts as an oxidant in AMO degradation. The preliminary chromatogram data display different products with varying pH reaction s, implying that AMO elimination using this 1 x 1 molecular sieve-structured MnO2 is by adsorption as well as oxidative degradation. A complementary experiment indicates that the amount of oxidatively degraded AMO increases substantially from 65.5% at 4 h to 95% at 48 h, whereas the AMO adsorbed onto MnO2 decreases slightly from 4.5% at4 h to 2.4% at 48 h. The oxidative degradation accounted for more AMO removal than adsorption over the whole reaction course, indicating that the oxidative reaction of AMO on MnO2 dominated the AMO removal. PMID:24350501

  9. Textural mesoporosity and the catalytic activity of mesoporous molecular sieves with wormhole framework structures

    SciTech Connect

    Pauly, T.R.; Liu, Y.; Pinnavaia, T.J.; Billinge, S.J.L.; Rieker, T.P.

    1999-09-29

    Three different water-alcohol cosolvent systems were used to assemble mesoporous molecular sieve silicas with wormhole framework structures (previously denoted HMS silicas) from an electrically neutral amine surfactant (S{degree}) and a silicon alkoxide precursor (I{degree}). The fundamental particle size and associated textural (interparticle) porosity of the disordered structures were correlated with the solubility of the surfactant in the water-alcohol cosolvents used for the S{degree}I{degree} assembly process. Polar cosolvents containing relatively low volume fractions of C{sub n}H{sub 2n+1}OH alcohols (n = 1--3) gave heterogeneous surfactant emulsions that assembled intergrown aggregates of small primary particles with high textural pore volumes (designated HMS-HTx). Conversely, three-dimensional, monolithic particles with little or no textural porosity (designated HMS-LTx) were formed from homogeneous surfactant solutions in lower polarity cosolvents. Aluminum substituted AL-HMS-HTx analogues with high textural porosity and improved framework accessibility also were shown to be much more efficient catalysts than AL-HMS-LTx or monolithic forms of hexagonal AL-MCM-41 for the sterically demanding condensed phase alkylation of 2,4-di-tert-butylphenol with cinnamyl alcohol. Transmission electron microscopy (TEM) and small-angle X-ray scattering (SAXS) studies verified the textural differences between wormhole HMS and electrostatically assembled hexagonal MCM-41 and SBA-3 molecular sieves. Power law fits to the scattering data indicated a surface fractal (D{sub s} = 2.76) for HMS-HTx, consistent with rough surfaces. A second power law at lower-q indicated the formation of a mass fractal (D{sub m} = 1.83) consistent with branching of small fundamental particles. Hexagonal MCM-41 and SBA-3 silicas, on the other hand, exhibited scattering properties consistent with moderately rough surfaces (D{sub s} = 2.35 and 2.22, respectively) and large particle diameters ({much

  10. Semi-Technical Cryogenic Molecular Sieve Bed for the Tritium Extraction System of the Test Blanket Module for ITER

    SciTech Connect

    Beloglazov, S.; Bekris, N.; Glugla, M.; Wagner, R.

    2005-07-15

    The tritium extraction from the ITER Helium Cooled Pebble Bed (HCPB) Test Blanket Module purge gas is proposed to be performed in a two steps process: trapping water in a cryogenic Cold Trap, and adsorption of hydrogen isotopes (H{sub 2}, HT, T{sub 2}) as well as impurities (N{sub 2}, O{sub 2}) in a Cryogenic Molecular Sieve Bed (CMSB) at 77K. A CMSB in a semi-technical scale (one-sixth of the flow rate of the ITER-HCPB) was design and constructed at the Forschungszentrum Karlsruhe. The full capacity of CMSB filled with 20 kg of MS-5A was calculated based on adsorption isotherm data to be 9.4 mol of H{sub 2} at partial pressure 120 Pa. The breakthrough tests at flow rates up to 2 Nm{sup 3}h{sup -1} of He with 110 Pa of H{sub 2} conformed with good agreement the adsorption capacity of the CMSB. The mass-transfer zone was found to be relatively narrow (12.5 % of the MS Bed height) allowing to scale up the CMSB to ITER flow rates.

  11. Synthesis, Characterization and Application of N-Ti/13X/MCM-41 Mesoporous Molecular Sieves.

    PubMed

    Tao, Hong; Nguyen, Nhat-Thien; Hei, Xiao-Hui; Nguyen, Cong Nguyen; Tsai, Hsiao-Hsin; Chang, I-Cheng; Chang, Chang-Tang

    2016-06-01

    Di-n-butyl phthalate (DBP) is a type of phthalate ester. In recent years, an increasing number of studies have examined the removal of DBP. In this study we use a composite material of N-Ti/13X/MCM-41, synthesized by nitrogen, molecular sieve 13X, tetrabutyl orthotitanate and tetraethyl orthosilicate as raw materials, CTAB as a structural template and tetrabutyl titanate and urea under hydrothermal conditions. The optimized experimental conditions, such as the amount of material, reaction time, pH value and initial concentration were tested. The surface areas of N-Ti/13X/MCM-41 were found to be 664 m2g(-1). TEM micrographs revealed N-Ti/13X/MCM-41 is consisting of aggregates of spherical particles, similar with standard synthesized MCM-41 (Mobil Composition of Matter No. 41). Through photocatalytic degradation experiments, the optimum degradation efficiency of DBP was more than 90% at a pH 6.0 with catalyst dosing of 0.15 g L(-1). PMID:27427754

  12. Mixed Matrix Carbon Molecular Sieve and Alumina (CMS-Al2O3) Membranes.

    PubMed

    Song, Yingjun; Wang, David K; Birkett, Greg; Martens, Wayde; Duke, Mikel C; Smart, Simon; Diniz da Costa, João C

    2016-01-01

    This work shows mixed matrix inorganic membranes prepared by the vacuum-assisted impregnation method, where phenolic resin precursors filled the pore of α-alumina substrates. Upon carbonisation, the phenolic resin decomposed into several fragments derived from the backbone of the resin matrix. The final stages of decomposition (>650 °C) led to a formation of carbon molecular sieve (CMS) structures, reaching the lowest average pore sizes of ~5 Å at carbonisation temperatures of 700 °C. The combination of vacuum-assisted impregnation and carbonisation led to the formation of mixed matrix of CMS and α-alumina particles (CMS-Al2O3) in a single membrane. These membranes were tested for pervaporative desalination and gave very high water fluxes of up to 25 kg m(-2) h(-1) for seawater (NaCl 3.5 wt%) at 75 °C. Salt rejection was also very high varying between 93-99% depending on temperature and feed salt concentration. Interestingly, the water fluxes remained almost constant and were not affected as feed salt concentration increased from 0.3, 1 and 3.5 wt%.

  13. Mixed Matrix Carbon Molecular Sieve and Alumina (CMS-Al2O3) Membranes

    NASA Astrophysics Data System (ADS)

    Song, Yingjun; Wang, David K.; Birkett, Greg; Martens, Wayde; Duke, Mikel C.; Smart, Simon; Diniz da Costa, João C.

    2016-07-01

    This work shows mixed matrix inorganic membranes prepared by the vacuum-assisted impregnation method, where phenolic resin precursors filled the pore of α-alumina substrates. Upon carbonisation, the phenolic resin decomposed into several fragments derived from the backbone of the resin matrix. The final stages of decomposition (>650 °C) led to a formation of carbon molecular sieve (CMS) structures, reaching the lowest average pore sizes of ~5 Å at carbonisation temperatures of 700 °C. The combination of vacuum-assisted impregnation and carbonisation led to the formation of mixed matrix of CMS and α-alumina particles (CMS-Al2O3) in a single membrane. These membranes were tested for pervaporative desalination and gave very high water fluxes of up to 25 kg m‑2 h‑1 for seawater (NaCl 3.5 wt%) at 75 °C. Salt rejection was also very high varying between 93–99% depending on temperature and feed salt concentration. Interestingly, the water fluxes remained almost constant and were not affected as feed salt concentration increased from 0.3, 1 and 3.5 wt%.

  14. Adsorbate shape selectivity: Separation of the HF/134a azeotrope over carbogenic molecular sieve

    SciTech Connect

    Hong, A.; Mariwala, R.K.; Kane, M.S.; Foley, H.C.

    1995-03-01

    Experimental evidence is provided for adsorptive shape selectivity in the separation of the azeotrope between HF and 1,1,1,2-tetrafluoroethane (134a) over pyrolyzed poly(furfuryl alcohol)-derived carbogenic molecular sieve (PPFA-CMS). The separation can be accomplished over coconut charcoal or Carbosieve G on the basis of the differences in the extent of equilibrium adsorption of HF and 134a. On these adsorbents 134a is more strongly bound than HF, thus it elutes much more slowly from the bed. The heat of adsorption for 134a in the vicinity of 200 C on Carbosieve G is {approximately}8.8 kcal/mol. In contrast, when the same azeotropic mixture is separated over PPFA-CMS prepared at 500 C, 134a is not adsorbed. As a result 134a elutes from the bed first, followed by HF. The reversal is brought about by the narrower pore size and pore size distribution of the PPFA-CMS versus that for Carbosieve G. Thus the separation over PPFA-CMS is an example of adsorbate shape selectivity and represents a limiting case of kinetic separation.

  15. [Adsorption characteristics of acetone and butanone onto honeycomb ZSM-5 molecular sieve].

    PubMed

    Du, Juan; Luan, Zhi-Qiang; Xie, Qiang; Ye, Ping-Wei; Li, Kai; Wang, Xi-Qin

    2013-12-01

    Adsorption capacity of acetone and acetone-butanone mixture onto honeycomb ZSM-5 molecular sieve was measured in this paper, and the influences of relative humidity, initial adsorbate concentration and airflow velocity on the adsorption process were investigated. Besides, adsorption performance parameters were calculated by Wheeler's equation. The results showed that relative humidity had no obvious influence on the acetone adsorption performance, which suggests that this material has good hydrophobic ability; in the low concentration range, the dynamic saturated adsorption capacity of acetone increased with the increase of initial concentration, but in the occasion of high concentration of acetone gas (more than 9 mg x L(-1)), the dynamic saturated adsorption capacity maintained at a certain level and did not vary with the increase of initial concentration; the increase of air flow velocity resulted in significant increase of acetone adsorption rate constant, at the same time the critical layer thickness of the adsorbent bed also increased significantly. In the cases of acetone-butanone mixture, the adsorption capacity of butanone onto ZSM-5 was clearly higher than that of acetone.

  16. Carbon molecular sieve membranes on porous composite tubular supports for high performance gas separations

    DOE PAGESBeta

    Lee, Pyung -Soo; Bhave, Ramesh R.; Nam, Seung -Eun; Kim, Daejin

    2016-01-11

    Thin carbon molecular sieve membranes (<500 nm) were fabricated inside of long geometry (9 inch) of stainless steel tubes with all welded construction. Alumina intermediate layer on porous stainless steel tube support was used to reduce effective support pore size and to provide a more uniform surface roughness. Novolac phenolic resin solution was then coated on the inside of porous stainless steel tube by slip casting while their viscosities were controlled from 5 centipoises to 30 centipoises. Carbonization was carried out at 700 °C in which thermal stress was minimized and high quality carbon films were prepared. The highest separationmore » performance characteristics were obtained using 20 cP phenolic resin solutions. The fabricated CMSM showed good separation factor for He/N2 462, CO2/N2 97, and O2/N2 15.4. As the viscosity of polymer precursor solution was reduced from 20 cP to 15 cP, gas permeance values almost doubled with somewhat lower separation factor He/N2 156, CO2/N2 88, and O2/N2 7.7.« less

  17. Tunable ionic-conductivity of collapsed Sandia octahedral molecular sieves (SOMS).

    SciTech Connect

    Pless, Jason; Nenoff, Tina Maria; Garino, Terry J.; Axness, Marlene

    2006-11-01

    This proposal focuses on the synthesis and characterization of ''tunable'' perovskite ceramics with resulting controlled strength and temperature of dielectric constants and/or with ionic conductivity. Traditional methods of synthesis involve high temperature oxide mixing and baking. We developed a new methodology of synthesis involving the (1) low temperature hydrothermal synthesis of metastable porous phases with ''tuned'' stoichiometry, and element types, and then (2) low temperature heat treatment to build exact stoichiometry perovskites, with the desired vacancy concentrations. This flexible pathway can lead to compositions and structures not attainable by conventional methods. During the course of this program, a series of Na-Nb perovskites were synthesized by calcining and collapsing microporous Sandia Octahedral Molecular Sieve (SOMS) phases. These materials were studied by various characterization techniques and conductivity measurements to better delineate stability and stoichiometry/bulk conductivity relationships. The conductivity can be altered by changing the concentration and type of the substituting framework cation(s) or by ion exchange of sodium. To date, the Na{sub 0.9}Mg{sub 0.1}Nb{sub 0.8}Ti{sub 0.2}O{sub 3-{delta}} shows the best conductivity.

  18. Mixed Matrix Carbon Molecular Sieve and Alumina (CMS-Al2O3) Membranes

    PubMed Central

    Song, Yingjun; Wang, David K.; Birkett, Greg; Martens, Wayde; Duke, Mikel C.; Smart, Simon; Diniz da Costa, João C.

    2016-01-01

    This work shows mixed matrix inorganic membranes prepared by the vacuum-assisted impregnation method, where phenolic resin precursors filled the pore of α-alumina substrates. Upon carbonisation, the phenolic resin decomposed into several fragments derived from the backbone of the resin matrix. The final stages of decomposition (>650 °C) led to a formation of carbon molecular sieve (CMS) structures, reaching the lowest average pore sizes of ~5 Å at carbonisation temperatures of 700 °C. The combination of vacuum-assisted impregnation and carbonisation led to the formation of mixed matrix of CMS and α-alumina particles (CMS-Al2O3) in a single membrane. These membranes were tested for pervaporative desalination and gave very high water fluxes of up to 25 kg m−2 h−1 for seawater (NaCl 3.5 wt%) at 75 °C. Salt rejection was also very high varying between 93–99% depending on temperature and feed salt concentration. Interestingly, the water fluxes remained almost constant and were not affected as feed salt concentration increased from 0.3, 1 and 3.5 wt%. PMID:27469389

  19. CIT-7, a crystalline, molecular sieve with pores bounded by 8 and 10-membered rings

    DOE PAGESBeta

    Schmidt, Joel E.; Xie, Dan; Rea, Thomas; Davis, Mark E.

    2015-01-23

    A new crystalline molecular sieve, denoted CIT-7, is synthesized using an imidazolium-based diquaternary organic structure directing agent (OSDA). The framework structure is determined from a combination of rotation electron diffraction and synchrotron X-ray powder diffraction data. The structure has 10 crystallographically unique tetrahedral atoms (T-atoms) in the unit cell, and can be described as an ordered arrangement of the [425462] mtw building unit and a previously unreported [4452] building unit. The framework contains a 2-dimensional pore system that is bounded by 10 T-atom rings (10-ring, 5.1 Å × 6.2 Å opening) that are connected with oval 8-rings (2.9 Å ×more » 5.5 Å opening) through medium-sized cavities (~7.9 Å) at the channel intersections. CIT-7 can be synthesized over a broad range of compositions including pure-silica and heteroatom, e.g., aluminosilicate and titanosilicate, containing variants.« less

  20. CIT-7, a crystalline, molecular sieve with pores bounded by 8 and 10-membered rings

    SciTech Connect

    Schmidt, Joel E.; Xie, Dan; Rea, Thomas; Davis, Mark E.

    2015-01-23

    A new crystalline molecular sieve, denoted CIT-7, is synthesized using an imidazolium-based diquaternary organic structure directing agent (OSDA). The framework structure is determined from a combination of rotation electron diffraction and synchrotron X-ray powder diffraction data. The structure has 10 crystallographically unique tetrahedral atoms (T-atoms) in the unit cell, and can be described as an ordered arrangement of the [425462] mtw building unit and a previously unreported [4452] building unit. The framework contains a 2-dimensional pore system that is bounded by 10 T-atom rings (10-ring, 5.1 Å × 6.2 Å opening) that are connected with oval 8-rings (2.9 Å × 5.5 Å opening) through medium-sized cavities (~7.9 Å) at the channel intersections. CIT-7 can be synthesized over a broad range of compositions including pure-silica and heteroatom, e.g., aluminosilicate and titanosilicate, containing variants.

  1. Passive CO{sub 2} removal using a carbon fiber composite molecular sieve

    SciTech Connect

    Burchell, T.D.; Judkins, R.R.

    1995-12-01

    Manufacture and characterization of a carbon fiber composite molecular sieve (CFCMS), and its efficacy as a CO{sub 2} gas adsorbent are reported. The CFCMS consists of an isotropic pitch derived carbon fiber and a phenolic resin derived carbon binder. Activation (selective gasification) of the CFCMS creates microporosity in the carbon fibers, yielding high micropore volumes (>0.5 cm{sup 3}/g) and BET surface areas (>1000 m{sup 2}/g). Moreover, the CFCMS material is a rigid, strong, monolith with an open structure that allows the free-flow of fluids through the material. This combination of properties provides an adsorbent material that has several distinct advantages over granular adsorbents in gas separation systems such as pressure swing adsorption (PSA) units. The results of our initial evaluations of the CO{sub 2} adsorption capacity and kinetics of CFCMS are reported. The room temperature CO{sub 2} adsorption capacity of CFCMS is >120 mg of CO{sub 2} per g of CFCMS. A proposed project is described that targets the development, over a three-year period, of a demonstration separation system based on CFCMS for the removal of CO{sub 2} from a flue gas slip stream at a coal-fired power plant. The proposed program would be conducted jointly with industrial and utility partners.

  2. Mixed Matrix Carbon Molecular Sieve and Alumina (CMS-Al2O3) Membranes.

    PubMed

    Song, Yingjun; Wang, David K; Birkett, Greg; Martens, Wayde; Duke, Mikel C; Smart, Simon; Diniz da Costa, João C

    2016-01-01

    This work shows mixed matrix inorganic membranes prepared by the vacuum-assisted impregnation method, where phenolic resin precursors filled the pore of α-alumina substrates. Upon carbonisation, the phenolic resin decomposed into several fragments derived from the backbone of the resin matrix. The final stages of decomposition (>650 °C) led to a formation of carbon molecular sieve (CMS) structures, reaching the lowest average pore sizes of ~5 Å at carbonisation temperatures of 700 °C. The combination of vacuum-assisted impregnation and carbonisation led to the formation of mixed matrix of CMS and α-alumina particles (CMS-Al2O3) in a single membrane. These membranes were tested for pervaporative desalination and gave very high water fluxes of up to 25 kg m(-2) h(-1) for seawater (NaCl 3.5 wt%) at 75 °C. Salt rejection was also very high varying between 93-99% depending on temperature and feed salt concentration. Interestingly, the water fluxes remained almost constant and were not affected as feed salt concentration increased from 0.3, 1 and 3.5 wt%. PMID:27469389

  3. Biomass-based palm shell activated carbon and palm shell carbon molecular sieve as gas separation adsorbents.

    PubMed

    Sethupathi, Sumathi; Bashir, Mohammed Jk; Akbar, Zinatizadeh Ali; Mohamed, Abdul Rahman

    2015-04-01

    Lignocellulosic biomass has been widely recognised as a potential low-cost source for the production of high added value materials and proved to be a good precursor for the production of activated carbons. One of such valuable biomasses used for the production of activated carbons is palm shell. Palm shell (endocarp) is an abundant by-product produced from the palm oil industries throughout tropical countries. Palm shell activated carbon and palm shell carbon molecular sieve has been widely applied in various environmental pollution control technologies, mainly owing to its high adsorption performance, well-developed porosity and low cost, leading to potential applications in gas-phase separation using adsorption processes. This mini-review represents a comprehensive overview of the palm shell activated carbon and palm shell carbon molecular sieve preparation method, physicochemical properties and feasibility of palm shell activated carbon and palm shell carbon molecular sieve in gas separation processes. Some of the limitations are outlined and suggestions for future improvements are pointed out.

  4. [Synergetic effects of silicon carbide and molecular sieve loaded catalyst on microwave assisted catalytic oxidation of toluene].

    PubMed

    Wang, Xiao-Hui; Bo, Long-Li; Liu, Hai-Nan; Zhang, Hao; Sun, Jian-Yu; Yang, Li; Cai, Li-Dong

    2013-06-01

    Molecular sieve loaded catalyst was prepared by impregnation method, microwave-absorbing material silicon carbide and the catalyst were investigated for catalytic oxidation of toluene by microwave irradiation. Research work examined effects of silicon carbide and molecular sieve loading Cu-V catalyst's mixture ratio as well as mixed approach changes on degradation of toluene, and characteristics of catalyst were measured through scanning electron microscope, specific surface area test and X-ray diffraction analysis. The result showed that the fixed bed reactor had advantages of both thermal storage property and low-temperature catalytic oxidation when 20% silicon carbide was filled at the bottom of the reactor, and this could effectively improve the utilization of microwave energy as well as catalytic oxidation efficiency of toluene. Under microwave power of 75 W and 47 W, complete-combustion temperatures of molecular sieve loaded Cu-V catalyst and Cu-V-Ce catalyst to toluene were 325 degrees C and 160 degrees C, respectively. Characteristics of the catalysts showed that mixture of rare-earth element Ce increased the dispersion of active components in the surface of catalyst, micropore structure of catalyst effectively guaranteed high adsorption capacity for toluene, while amorphous phase of Cu and V oxides increased the activity of catalyst greatly.

  5. Titanium(IV) in the organic-structure-directing-agent-free synthesis of hydrophobic and large-pore molecular sieves as redox catalysts.

    PubMed

    Wang, Jingui; Yokoi, Toshiyuki; Kondo, Junko N; Tatsumi, Takashi; Zhao, Yanli

    2015-08-10

    Titanium(IV) incorporated into the framework of molecular sieves can be used as a highly active and sustainable catalyst for the oxidation of industrially important organic molecules. Unfortunately, the current process for the incorporation of titanium(IV) requires a large amount of expensive organic molecules used as organic-structure-directing agents (OSDAs), and this significantly increases the production costs and causes environmental problems owing to the removal of OSDAs by pyrolysis. Herein, an OSDA-free process was developed to incorporate titanium(IV) into BEA-type molecular sieves for the first time. More importantly, the hydrophobic environment and the robust, 3 D, and large pore structure of the titanium(IV)-incorporated molecular sieves fabricated from the OSDA-free process created a catalyst that was extremely active and selective for the epoxidation of bulky cyclooctene in comparison to Ti-incorporated BEA-type molecular sieves synthesized with OSDAs and commercial titanosilicate TS-1.

  6. Synthesis of multi-wall carbon nanotubes by the pyrolysis of ethanol on Fe/MCM-41 mesoporous molecular sieves

    NASA Astrophysics Data System (ADS)

    Zhao, Qian; Li, Yanhui; Zhou, Xuping; Jiang, Tingshun; Li, Changsheng; Yin, Hengbo

    2010-03-01

    Ordered hexagonal arrangement MCM-41 mesoporous molecular sieves were synthesized by the traditional hydrothermal method, and Fe-loaded MCM-41 mesoporous molecular sieves (Fe/MCM-41) were prepared by the wet impregnation method. Their mesoporous structures were testified by X-ray diffraction (XRD) and the N 2 physical adsorption technique. Carbon nanotubes (CNTs) were synthesized by the chemical vapor deposition (CVD) method via the pyrolysis of ethanol at atmospheric pressure using Fe/MCM-41 as a catalytic template. The effect of different reaction temperatures ranging from 600 to 800 ∘C on the formation of CNTs was investigated. The resulting carbon materials were characterized by various physicochemical techniques such as transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), and Raman spectroscopy. The results show that multi-wall carbon nanotubes (MWCNTs) with an internal diameter of ca. 7.7 nm and an external diameter of ca. 16.9 nm were successfully obtained by the pyrolysis of ethanol at 800 ∘C utilizing Fe/MCM-41 as a catalytic template.

  7. N-methyldiethanolamine: a multifunctional structure-directing agent for the synthesis of SAPO and AlPO molecular sieves.

    PubMed

    Wang, Dehua; Tian, Peng; Fan, Dong; Yang, Miao; Gao, Beibei; Qiao, Yuyan; Wang, Chan; Liu, Zhongmin

    2015-05-01

    In the present study, N-methyldiethanolamine (MDEA) is demonstrated to be a multifunctional structure-directing agent for the synthesis of aluminophosphate-based molecular sieves. Four types of molecular sieves, including SAPO-34, -35, AlPO-9 and -22, are for the first time acquired with MDEA as a novel template. The phase selectivity of the present synthesis is found to be condition-dependent. SAPO-34 (CHA) crystallizes from a conventional hydrothermal system with a higher MDEA concentration. When using MDEA as both the template and solvent, pure SAPO-35 (LEV) is obtained from the synthetic gel with a high P2O5/Al2O3 ratio of (2-3), in which the concentration of MDEA could be varied in a wide range. AlPO-9 and AlPO-22 (AWW) are synthesized under the similar conditions to SAPO-35, except without the addition of Si source. The physicochemical properties of the obtained samples are investigated by XRD, XRF, SEM, N2 physisorption, TG-DSC, and various NMR spectra ((13)C, (29)Si, (27)Al and (31)P). Both SAPO-34 and SAPO-35 show good thermal stability, large surface area, and high pore volume. The catalytic performance of SAPO-34 is evaluated by the methanol-to-olefins (MTO) reaction and a good (C2H4+C3H6) selectivity of 82.7% has been achieved. PMID:25616250

  8. Time-Dependent CO[subscript 2] Sorption Hysteresis in a One-Dimensional Microporous Octahedral Molecular Sieve

    SciTech Connect

    Espinal, Laura; Wong-Ng, Winnie; Kaduk, James A.; Allen, Andrew J.; Snyder, Chad R.; Chiu, Chun; Siderius, Daniel W.; Li, Lan; Cockayne, Eric; Espinal, Anais E.; Suib, Steven L.

    2014-09-24

    The development of sorbents for next-generation CO{sub 2} mitigation technologies will require better understanding of CO{sub 2}/sorbent interactions. Among the sorbents under consideration are shape-selective microporous molecular sieves with hierarchical pore morphologies of reduced dimensionality. We have characterized the non-equilibrium CO{sub 2} sorption of OMS-2, a well-known one-dimensional microporous octahedral molecular sieve with manganese oxide framework. Remarkably, we find that the degree of CO{sub 2} sorption hysteresis increases when the gas/sorbent system is allowed to equilibrate for longer times at each pressure step. Density functional theory calculations indicate a 'gate-keeping' role of the cation in the tunnel, only allowing CO{sub 2} molecules to enter fully into the tunnel via a highly unstable transient state when CO{sub 2} loadings exceed 0.75 mmol/g. The energy barrier associated with the gate-keeping effect suggests an adsorption mechanism in which kinetic trapping of CO{sub 2} is responsible for the observed hysteretic behavior.

  9. Spray-dried powders enhance vaginal siRNA delivery by potentially modulating the mucus molecular sieve structure.

    PubMed

    Wu, Na; Zhang, Xinxin; Li, Feifei; Zhang, Tao; Gan, Yong; Li, Juan

    2015-01-01

    Vaginal small interfering RNA (siRNA) delivery provides a promising strategy for the prevention and treatment of vaginal diseases. However, the densely cross-linked mucus layer on the vaginal wall severely restricts nanoparticle-mediated siRNA delivery to the vaginal epithelium. In order to overcome this barrier and enhance vaginal mucus penetration, we prepared spray-dried powders containing siRNA-loaded nanoparticles. Powders with Pluronic F127 (F127), hydroxypropyl methyl cellulose (HPMC), and mannitol as carriers were obtained using an ultrasound-assisted spray-drying technique. Highly dispersed dry powders with diameters of 5-15 μm were produced. These powders showed effective siRNA protection and sustained release. The mucus-penetrating properties of the powders differed depending on their compositions. They exhibited different potential of opening mesh size of molecular sieve in simulated vaginal mucus system. A powder formulation with 0.6% F127 and 0.1% HPMC produced the maximum increase in the pore size of the model gel used to simulate vaginal mucus by rapidly extracting water from the gel and interacting with the gel; the resulting modulation of the molecular sieve effect achieved a 17.8-fold improvement of siRNA delivery in vaginal tract and effective siRNA delivery to the epithelium. This study suggests that powder formulations with optimized compositions have the potential to alter the steric barrier posed by mucus and hold promise for effective vaginal siRNA delivery.

  10. Spray-dried powders enhance vaginal siRNA delivery by potentially modulating the mucus molecular sieve structure

    PubMed Central

    Wu, Na; Zhang, Xinxin; Li, Feifei; Zhang, Tao; Gan, Yong; Li, Juan

    2015-01-01

    Vaginal small interfering RNA (siRNA) delivery provides a promising strategy for the prevention and treatment of vaginal diseases. However, the densely cross-linked mucus layer on the vaginal wall severely restricts nanoparticle-mediated siRNA delivery to the vaginal epithelium. In order to overcome this barrier and enhance vaginal mucus penetration, we prepared spray-dried powders containing siRNA-loaded nanoparticles. Powders with Pluronic F127 (F127), hydroxypropyl methyl cellulose (HPMC), and mannitol as carriers were obtained using an ultrasound-assisted spray-drying technique. Highly dispersed dry powders with diameters of 5–15 μm were produced. These powders showed effective siRNA protection and sustained release. The mucus-penetrating properties of the powders differed depending on their compositions. They exhibited different potential of opening mesh size of molecular sieve in simulated vaginal mucus system. A powder formulation with 0.6% F127 and 0.1% HPMC produced the maximum increase in the pore size of the model gel used to simulate vaginal mucus by rapidly extracting water from the gel and interacting with the gel; the resulting modulation of the molecular sieve effect achieved a 17.8-fold improvement of siRNA delivery in vaginal tract and effective siRNA delivery to the epithelium. This study suggests that powder formulations with optimized compositions have the potential to alter the steric barrier posed by mucus and hold promise for effective vaginal siRNA delivery. PMID:26347257

  11. Activation and Micropore Structure Determination of Carbon-Fiber Composite Molecular Sieves

    SciTech Connect

    Jagtoyen, M.

    1995-01-01

    levels of burnoff above about 40%, the extent of contraction is sufficient to produce stresses that result in fracture. Activated composites have been evaluated for the separation of CH{sub 4}-CO{sub 2} mixtures, and an apparatus has been constructed specifically for this purpose. Samples activated to low burn-off (5-7% wt loss) with low surface areas (from 300-500m{sup 2}/g) give much better separation of CO{sub 2} and CH{sub 4}, than samples produced at higher burnoff, and there appears to be no benefit in producing composites at burnoffs higher than 10%. The greater separation efficiency obtained at low burnoff means that the most effective CFCMS can be produced at relatively low cost. Continuing work will attempt to define the parameters that influence this gas separation, and whether these are applicable to other gas mixtures. Five samples of CFCMS have been recently prepared for shipment to British Oxygen Corporation (BOC) for testing as molecular sieves. The samples were machined to specific dimensions at ORNL (approx. 2.5 cm diameter x 1.25 cm thick) and activated at CAER. The samples were produced to different burn-off, but all have relatively narrow pore size distributions with average pore diameters around 6A.

  12. Formation of hydroxyl-functionalized stilbenoid molecular sieves at the liquid/solid interface on top of a 1-decanol monolayer

    NASA Astrophysics Data System (ADS)

    Bellec, Amandine; Arrigoni, Claire; Douillard, Ludovic; Fiorini-Debuisschert, Céline; Mathevet, Fabrice; Kreher, David; Attias, André-Jean; Charra, Fabrice

    2014-10-01

    Specific molecular tectons can be designed to form molecular sieves through self-assembly at the solid-liquid interface. After demonstrating a model tecton bearing apolar alkyl chains, we then focus on a modified structure involving asymmetric functionalization of some alkyl chains with polar hydroxyl groups in order to get chemical selectivity in the sieving. As the formation of supramolecular self-assembled networks strongly depends on molecule-molecule, molecule-substrate and molecule-solvent interactions, we compared the tectons’ self-assembly on graphite for two types of solvent. We demonstrate the possibility to create hydroxylated stilbenoid molecular sieves by using 1-decanol as a solvent. Interestingly, with this solvent, the porous network is developed on top of a 1-decanol monolayer.

  13. Carbon Molecular Sieve Membrane as a True One Box Unit for Large Scale Hydrogen Production

    SciTech Connect

    Liu, Paul

    2012-05-01

    IGCC coal-fired power plants show promise for environmentally-benign power generation. In these plants coal is gasified to syngas then processed in a water gas-shift (WGS) reactor to maximize the hydrogen/CO{sub 2} content. The gas stream can then be separated into a hydrogen rich stream for power generation and/or further purified for sale as a chemical and a CO{sub 2} rich stream for the purpose of carbon capture and storage (CCS). Today, the separation is accomplished using conventional absorption/desorption processes with post CO{sub 2} compression. However, significant process complexity and energy penalties accrue with this approach, accounting for ~20% of the capital cost and ~27% parasitic energy consumption. Ideally, a one-box process is preferred in which the syngas is fed directly to the WGS reactor without gas pre-treatment, converting the CO to hydrogen in the presence of H{sub 2}S and other impurities and delivering a clean hydrogen product for power generation or other uses. The development of such a process is the primary goal of this project. Our proposed "one-box" process includes a catalytic membrane reactor (MR) that makes use of a hydrogen-selective, carbon molecular sieve (CMS) membrane, and a sulfur-tolerant Co/Mo/Al{sub 2}O{sub 3} catalyst. The membrane reactor's behavior has been investigated with a bench top unit for different experimental conditions and compared with the modeling results. The model is used to further investigate the design features of the proposed process. CO conversion >99% and hydrogen recovery >90% are feasible under the operating pressures available from IGCC. More importantly, the CMS membrane has demonstrated excellent selectivity for hydrogen over H{sub 2}S (>100), and shown no flux loss in the presence of a synthetic "tar"-like material, i.e., naphthalene. In summary, the proposed "one-box" process has been successfully demonstrated with the bench-top reactor. In parallel we have successfully designed and

  14. Mathematical model and calculation algorithm of micro and meso levels of separation process of gaseous mixtures in molecular sieves

    SciTech Connect

    Umarova, Zhanat; Botayeva, Saule; Yegenova, Aliya; Usenova, Aisaule

    2015-05-15

    In the given article, the main thermodynamic aspects of the issue of modeling diffusion transfer in molecular sieves have been formulated. Dissipation function is used as a basic notion. The differential equation, connecting volume flow with the change of the concentration of catchable component has been derived. As a result, the expression for changing the concentration of the catchable component and the coefficient of membrane detecting has been received. As well, the system approach to describing the process of gases separation in ultra porous membranes has been realized and micro and meso-levels of mathematical modeling have been distinguished. The non-ideality of the shared system is primarily taken into consideration at the micro-level and the departure from the diffusion law of Fick has been taken into account. The calculation method of selectivity considering fractal structure of membranes has been developed at the meso level. The calculation algorithm and its software implementation have been suggested.

  15. Integrated Testing of a 4-Bed Molecular Sieve, Air-Cooled Temperature Swing Adsorption Compressor, and Sabatier Engineering Development Unit

    NASA Technical Reports Server (NTRS)

    Knox, James C.; Miller, Lee; Campbell, Melissa; Mulloth, Lila; Varghese, Mini

    2006-01-01

    Accumulation and subsequent compression of carbon dioxide that is removed from the space cabin are two important processes involved in a closed-loop air revitalization scheme of the International Space Station (ISS). The 4-Bed Molecular Sieve (4BMS) of ISS currently operates in an open loop mode without a compressor. The Sabatier Engineering Development Unit (EDU) processes waste CO2 to provide water to the crew. This paper reports the integrated 4BMS, air-cooled Temperature Swing Adsorption Compressor (TSAC), and Sabatier EDU testing. The TSAC prototype was developed at NASA Ames Research Center (ARC). The 4BMS was modified to a functionally flight-like condition at NASA Marshall Space Flight Center (MSFC). Testing was conducted at MSFC. The paper provides details of the TSAC operation at various CO2 loadings and corresponding performance of the 4BMS and Sabatier.

  16. Synthesis of an extra-large molecular sieve using proton sponges as organic structure-directing agents

    PubMed Central

    Martínez-Franco, Raquel; Moliner, Manuel; Yun, Yifeng; Sun, Junliang; Wan, Wei; Zou, Xiaodong; Corma, Avelino

    2013-01-01

    The synthesis of crystalline microporous materials containing large pores is in high demand by industry, especially for the use of these materials as catalysts in chemical processes involving bulky molecules. An extra-large–pore silicoaluminophosphate with 16-ring openings, ITQ-51, has been synthesized by the use of bulky aromatic proton sponges as organic structure-directing agents. Proton sponges show exceptional properties for directing extra-large zeolites because of their unusually high basicity combined with their large size and rigidity. This extra-large–pore material is stable after calcination, being one of the very few examples of hydrothermally stable molecular sieves containing extra-large pores. The structure of ITQ-51 was solved from submicrometer-sized crystals using the rotation electron diffraction method. Finally, several hypothetical zeolites related to ITQ-51 have been proposed. PMID:23431186

  17. Production of carbon molecular sieves from Illinois coal. Final technical report, 1 September, 1992--31 August 1993

    SciTech Connect

    Lizzio, A.A.; Rostam-Abadi, M.

    1993-12-31

    Carbon molecular sieves (CMS) have become an increasingly important class of adsorbents for use in gas separation and recovery processes. The overall objective of this project is to determine whether Illinois Basin coals are a suitable feedstock for the production of CMS and to evaluate the potential application of these products in commercial gas separation processes. In Phase 1 of this project, gram quantities of char were prepared from Illinois coal in a fixed-bed reactor under a wide range of pyrolysis and activation conditions. Chars having surface areas of 1,500--2,100 m{sup 2}/g were produced by chemical activation using potassium hydroxide (KOH) as the chemical activant. These high surface area (HSA) chars had more than twice the adsorption capacity of commercial molecular sieves. The kinetics of adsorption of various gases, e.g., O{sub 2}, N{sub 2}, CO{sub 2}, CH{sub 4}, and H{sub 2}, on these chars at 25 C was determined. Several chars showed good potential for efficient O{sub 2}/N{sub 2}, CO{sub 2}/CH{sub 4} and CH{sub 4}/H{sub 2} separation. In Phase 2 of this project, larger quantities of char are being prepared from Illinois coal in a batch fluidized-bed reactor and in a continuous rotary tube kiln. The ability of these chars to separate binary gas mixtures is tested in an adsorption column/gas chromatography system. Oxygen and nitrogen breakthrough curves obtained for selected chars were compared to those of a commercial zeolite. Selected chars were subjected to a nitric acid oxidation treatment. The air separation capability of nitric acid treated char was strongly dependent on the outgassing conditions used prior to an O{sub 2}/N{sub 2} adsorption experiment. An outgassing temperature of 130--160 C produced chars with the most favorable air separation properties. 61 refs.

  18. A novel molecular sieve supporting material for enhancing activity and stability of Ag3PO4 photocatalyst

    NASA Astrophysics Data System (ADS)

    Wu, Qiang; Wang, Peifu; Niu, Futao; Huang, Cunping; Li, Yang; Yao, Weifeng

    2016-08-01

    A small-pore silicon-substituted silicon aluminum phosphate (SAPO-34) molecular sieve, for the first time, is reported to significantly increase both the activity and life span of Ag3PO4 photocatalyst for visible-light degradation of methylene blue (MB) and rhodamine B (RhB). Results show that 60 wt.% Ag3PO4/SAPO-34 exhibits the highest photocatalytic degradation efficiencies for both MB (91.0% degradation within 2.0 min) and RhB (91.0% degradation within 7.0 min). In comparison, pure Ag3PO4 powder photocatalyst requires 8.0 min and 12.0 min for decomposing 91.0% of MB and RhB, respectively. During MB degradation the rate constant for 60 wt.% Ag3PO4/SAPO-34 increases 317.2% in comparison with the rate constant of pure Ag3PO4. This activity is also much higher than literature reported composite or supported Ag3PO4 photocatalysts. In three photocatalytic runs for the degradation of RhB, the rate constant for 60 wt.% Ag3PO4/SAPO-34 reduces from 0.33 to 0.18 min-1 (45.5% efficiency loss). In contrast, the rate constant of pure Ag3PO4 catalyst decreases from 0.2 to 0.07 min-1 (80.0% efficiency loss). All experimental results have shown that small pores and zero light absorption loss of SAPO-34 molecular sieves minimize Ag3PO4 loading, enhance photocatalytic activity and prolong the lifespan of Ag3PO4 photocatalyst.

  19. Titanium(IV) in the organic-structure-directing-agent-free synthesis of hydrophobic and large-pore molecular sieves as redox catalysts.

    PubMed

    Wang, Jingui; Yokoi, Toshiyuki; Kondo, Junko N; Tatsumi, Takashi; Zhao, Yanli

    2015-08-10

    Titanium(IV) incorporated into the framework of molecular sieves can be used as a highly active and sustainable catalyst for the oxidation of industrially important organic molecules. Unfortunately, the current process for the incorporation of titanium(IV) requires a large amount of expensive organic molecules used as organic-structure-directing agents (OSDAs), and this significantly increases the production costs and causes environmental problems owing to the removal of OSDAs by pyrolysis. Herein, an OSDA-free process was developed to incorporate titanium(IV) into BEA-type molecular sieves for the first time. More importantly, the hydrophobic environment and the robust, 3 D, and large pore structure of the titanium(IV)-incorporated molecular sieves fabricated from the OSDA-free process created a catalyst that was extremely active and selective for the epoxidation of bulky cyclooctene in comparison to Ti-incorporated BEA-type molecular sieves synthesized with OSDAs and commercial titanosilicate TS-1. PMID:26073555

  20. Platinum-nickel frame within metal-organic framework fabricated in situ for hydrogen enrichment and molecular sieving

    NASA Astrophysics Data System (ADS)

    Li, Zhi; Yu, Rong; Huang, Jinglu; Shi, Yusheng; Zhang, Diyang; Zhong, Xiaoyan; Wang, Dingsheng; Wu, Yuen; Li, Yadong

    2015-09-01

    Developing catalysts that provide the effective activation of hydrogen and selective absorption of substrate on metal surface is crucial to simultaneously improve activity and selectivity of hydrogenation reaction. Here we present an unique in situ etching and coordination synthetic strategy for exploiting a functionalized metal-organic framework to incorporate the bimetallic platinum-nickel frames, thereby forming a frame within frame nanostructure. The as-grown metal-organic framework serves as a `breath shell' to enhance hydrogen enrichment and activation on platinum-nickel surface. More importantly, this framework structure with defined pores can provide the selective accessibility of molecules through its one-dimensional channels. In a mixture containing four olefins, the composite can selectively transport the substrates smaller than its pores to the platinum-nickel surface and catalyse their hydrogenation. This molecular sieve effect can be also applied to selectively produce imines, which are important intermediates in the reductive imination of nitroarene, by restraining further hydrogenation via cascade processes.

  1. Preparation and application of zirconium sulfate supported on SAPO-34 molecular sieve as solid acid catalyst for esterification

    SciTech Connect

    Xu, Dongyan Ma, Hong; Cheng, Fei

    2014-05-01

    Graphical abstract: - Highlights: • SAPO-34 supported zirconium sulfate solid acid catalyst was prepared. • Esterification of acetic acid with ethanol can be catalyzed by ZS/SAPO-34. • The hydration of ZS is vital to the acidic property and catalytic performance. • The ZS/SAPO-34 catalyst treated at 200 °C shows good reusability. - Abstract: Zirconium sulfate (ZS) was supported on SAPO-34 molecular sieve by using an incipient wetness impregnation method with zirconium sulfate as the precursor. The as-prepared catalysts were used as solid acid catalyst for esterification reaction of acetic acid with ethanol. The influence of calcination temperature on the acidic property, catalytic activity, and reusability of ZS/SAPO-34 catalysts were mainly investigated. FT-IR, SEM, EDS and TG analysis have been carried out to demonstrate the characteristics of ZS/SAPO-34 catalysts. It was found that the 30 wt%ZS/SAPO-34 catalysts display the property of superacid irrespective of calcination temperature. The ZS/SAPO-34 catalyst treated at 200 °C can enhance the interaction between the supported ZS and SAPO-34 and keep the catalyst remaining substantially active after several reaction cycles. However, further increasing calcination temperature will cause the transfer of ZS from hydrate to anhydrous phase, and thus the decrease of activity.

  2. Interlinked Test Results for Fusion Fuel Processing and Blanket Tritium Recovery Systems Using Cryogenic Molecular Sieve Bed

    SciTech Connect

    Yamanishi, Toshihiko; Hayashi, Takumi; Kawamura, Yoshinori; Iwai, Yasunori; Isobe, Kanetsugu; Uzawa, Masayuki; Nishi, Masataka

    2005-07-15

    A simulated fuel processing (cryogenic distillation columns and a palladium diffuser) and CMSB (cryogenic molecular sieve bed) systems were linked together, and were operated. The validity of the CMSB was discussed through this experiment as an integrated system for the recovery of blanket tritium. A gas stream of hydrogen isotopes and He was supplied to the CMSB as the He sweep gas in blanket of a fusion reactor. After the breakthrough of tritium was observed, regeneration of the CMSB was carried out by evacuating and heating. The hydrogen isotopes were finally recovered by the diffuser. At first, only He gas was sent by the evacuating. The hydrogen isotopes gas was then rapidly released by the heating. The system worked well against the above drastic change of conditions. The amount of hydrogen isotopes gas finally recovered by the diffuser was in good agreement with that adsorbed by the CMSB. The dynamic behaviors (breakthrough and regeneration) of the system were explained well by a set of basic codes.

  3. An efficient synthesis of graphenated carbon nanotubes over the tailored mesoporous molecular sieves by chemical vapor deposition

    SciTech Connect

    Atchudan, R.; Joo, Jin.; Pandurangan, A.

    2013-06-01

    Highlights: ► Tailored 3D cubic Ni/KIT-6 with large pores was synthesized successfully. ► The new hybrid g-CNTs in large scale were synthesized using Ni/KIT-6 by CVD method. ► The use of mesoporous material by CVD method would be an ideal choice to prepare g-CNTs at reasonable cost. ► This type of g-CNTs might be a new avenue for nano-electronic applications. - Abstract: The new hybrid of graphenated carbon nanotubes (g-CNTs) was superior to either CNTs or graphene. Mesoporous 3D cubic Ni/KIT-6 were synthesized hydrothermally through organic template route and then were used as catalytic template for the production of g-CNTs using acetylene as a carbon precursor by chemical vapor deposition (CVD) method. The deposited new hybrid carbon materials were purified and analyzed by various physico-chemical techniques such as XRD, TGA, SEM, TEM and Raman spectroscopy techniques. The graphitization of CNTs was confirmed by TGA and HRTEM studies. Thermal stability, surface morphology, and structural morphology of these materials were revealed by TGA, SEM and TEM analysis, respectively. Moreover, the tailored mesoporous Ni/KIT-6 molecular sieves were found to possess better quality and massive quantity of g-CNTs produced compared to other catalytic template route.

  4. Controllable deformation of salt water-filled carbon nanotubes using an electric field with application to molecular sieving.

    PubMed

    Ye, Hongfei; Zheng, Yonggang; Zhang, Zhongqiang; Zhang, Hongwu; Chen, Zhen

    2016-08-01

    Precisely controlling the deformation of carbon nanotubes (CNTs) has practical application in the development of nanoscale functional devices, although it is a challenging task. Here, we propose a novel method to guide the deformation of CNTs through filling them with salt water and applying an electric field. With the electric field along the axial direction, the height of CNTs is enlarged by the axial electric force due to the internal ions and polar water molecules. Under an electric field with two mutually orthogonal components, the transverse electric force could further induce the bending deformation of CNTs. Based on the classical rod and beam theories, two mechanical models are constructed to verify and quantitatively describe the relationships between the tension and bending deformations of CNTs and the electric field intensity. Moreover, by means of the electric field-driven tension behavior of CNTs, we design a stretchable molecular sieve to control the flow rate of mixed gas and collect a single high-purity gas. The present work opens up new avenues in the design and fabrication of nanoscale controlling units. PMID:27335235

  5. Platinum–nickel frame within metal-organic framework fabricated in situ for hydrogen enrichment and molecular sieving

    PubMed Central

    Li, Zhi; Yu, Rong; Huang, Jinglu; Shi, Yusheng; Zhang, Diyang; Zhong, Xiaoyan; Wang, Dingsheng; Wu, Yuen; Li, Yadong

    2015-01-01

    Developing catalysts that provide the effective activation of hydrogen and selective absorption of substrate on metal surface is crucial to simultaneously improve activity and selectivity of hydrogenation reaction. Here we present an unique in situ etching and coordination synthetic strategy for exploiting a functionalized metal-organic framework to incorporate the bimetallic platinum–nickel frames, thereby forming a frame within frame nanostructure. The as-grown metal-organic framework serves as a ‘breath shell' to enhance hydrogen enrichment and activation on platinum–nickel surface. More importantly, this framework structure with defined pores can provide the selective accessibility of molecules through its one-dimensional channels. In a mixture containing four olefins, the composite can selectively transport the substrates smaller than its pores to the platinum–nickel surface and catalyse their hydrogenation. This molecular sieve effect can be also applied to selectively produce imines, which are important intermediates in the reductive imination of nitroarene, by restraining further hydrogenation via cascade processes. PMID:26391605

  6. Ionothermal Synthesis of MnAPO-SOD Molecular Sieve without the Aid of Organic Structure-Directing Agents.

    PubMed

    Liu, Hao; Tian, Zhijian; Wang, Lei; Wang, Yasong; Li, Dawei; Ma, Huaijun; Xu, Renshun

    2016-02-15

    An SOD-type metalloaluminophosphate molecular sieve (denoted as SOD-Mn) was ionothermally synthesized by introducing manganese(II) cations into the reaction mixture via MnO-acid or MnO2-reductant reactions. Composition and structure analyses results show that two kinds of manganese(II) cations exist in the SOD-Mn structure. Part of the manganese(II) cations isomorphously substitute the framework aluminum(III) with a substitution degree of ∼30%. The rest of the manganese(II) cations occupy a fraction of the sod cages in their hydrated forms. A comprehensive investigation of the synthesis parameters, crystal sizes, and crystallization kinetics indicates that the in situ released hydrated manganese(II) cations direct the formation of SOD-Mn. Such structure-directing effect may be inhibited by both the fluorination of manganese(II) cations and the water accumulation during crystallization. In the fluoride anion-containing reaction mixture with a low ionic liquid content, the crystallization process is strongly suppressed, and large SOD-Mn single crystals of over 200 μm in size are yielded. SOD-Mn is free from organics and shows improved thermal stability compared with metalloaluminophosphates synthesized by using organic structure-directing agents.

  7. Controllable deformation of salt water-filled carbon nanotubes using an electric field with application to molecular sieving

    NASA Astrophysics Data System (ADS)

    Ye, Hongfei; Zheng, Yonggang; Zhang, Zhongqiang; Zhang, Hongwu; Chen, Zhen

    2016-08-01

    Precisely controlling the deformation of carbon nanotubes (CNTs) has practical application in the development of nanoscale functional devices, although it is a challenging task. Here, we propose a novel method to guide the deformation of CNTs through filling them with salt water and applying an electric field. With the electric field along the axial direction, the height of CNTs is enlarged by the axial electric force due to the internal ions and polar water molecules. Under an electric field with two mutually orthogonal components, the transverse electric force could further induce the bending deformation of CNTs. Based on the classical rod and beam theories, two mechanical models are constructed to verify and quantitatively describe the relationships between the tension and bending deformations of CNTs and the electric field intensity. Moreover, by means of the electric field-driven tension behavior of CNTs, we design a stretchable molecular sieve to control the flow rate of mixed gas and collect a single high-purity gas. The present work opens up new avenues in the design and fabrication of nanoscale controlling units.

  8. Effects of octahedral molecular sieve on treatment performance, microbial metabolism, and microbial community in expanded granular sludge bed reactor.

    PubMed

    Pan, Fei; Xu, Aihua; Xia, Dongsheng; Yu, Yang; Chen, Guo; Meyer, Melissa; Zhao, Dongye; Huang, Ching-Hua; Wu, Qihang; Fu, Jie

    2015-12-15

    This study evaluated the effects of synthesized octahedral molecular sieve (OMS-2) nanoparticles on the anaerobic microbial community in a model digester, expanded granular sludge bed (EGSB) reactor. The addition of OMS-2 (0.025 g/L) in the EGSB reactors resulted in an enhanced operational performance, i.e., COD removal and biogas production increased by 4% and 11% respectively, and effluent volatile fatty acid (VFA) decreased by 11% relative to the control group. The Biolog EcoPlate™ test was employed to investigate microbial metabolism in the EGSB reactors. Results showed that OMS-2 not only increased the microbial metabolic level but also significantly changed the community level physiological profiling of the microorganisms. The Illumina MiSeq high-throughput sequencing of 16S rRNA gene indicated OMS-2 enhanced the microbial diversity and altered the community structure. The largest bacterial genus Lactococcus, a lactic acid bacterium, reduced from 29.3% to 20.4% by abundance in the presence of 0.25 g/L OMS-2, which may be conducive to decreasing the VFA production and increasing the microbial diversity. OMS-2 also increased the quantities of acetogenic bacteria and Archaea, and promoted the acetogenesis and methanogenesis. The X-ray photoelectron spectroscopy illustrated that Mn(IV)/Mn(III) with high redox potential in OMS-2 were reduced to Mn(II) in the EGSB reactors; this in turn affected the microbial community. PMID:26397455

  9. Protein sterilization method of firefly luciferase using reduced pressure and molecular sieves

    NASA Technical Reports Server (NTRS)

    Chappelle, E. W.; Rich, E., Jr. (Inventor)

    1973-01-01

    The sterilization of the protein fruitfly luciferase under conditions that prevent denaturation is examined. Denaturation is prevented by heating the protein in contact with molecular seives and under a reduced pressure of the order of 0.00005 millimeters of mercury.

  10. Glycidol-modified gels for molecular-sieve chromatography. Surface hydrophilization and pore size reduction.

    PubMed

    Eriksson, K O

    1987-11-01

    Divinyl sulfone-crosslinked agarose gels were made hydrophilic by coupling glycidol to the agarose chains. The concentration of glycidol in the reaction mixture determines the pore size of the gels (the glycidol molecules probably form polymers, the degree of polymerization increasing with the glycidol concentration). Gels prepared with moderate glycidol concentrations are still porous enough to be used for separation of proteins and peptides. Gels with a high degree of glycidol polymerization are suited for desalting of low-molecular-weight compounds, for instance peptides.

  11. SSZ-26 and SSZ-33: Two molecular sieves with intersecting 10- and 12-ring pores

    SciTech Connect

    Lobo, R.F.; Li, H.X.; Davis, M.E. ); Pan, M.; Crozier, P.A. )

    1993-12-03

    The framework structures of two closely related molecular seives, SSZ-26 and SSZ-33, are described. These materials possess a previously missing but desired structural feature in a group of industrially significant zeolites. They contain a three-dimensional pore system that provides access to the crystal interior through both 10- and 12-rings. This property is a consequence of the organic structure-directing agents used in the synthesis of these materials. These materials are examples of the purposeful design of a micropore architecture. Both SSZ-26 and SSZ-33 contain the 4=4-1 building unit that had been previously found only in natural zeolites.

  12. Atmospheric weathering and silica-coated feldspar: analogy with zeolite molecular sieves, granite weathering, soil formation, ornamental slabs, and ceramics.

    PubMed

    Smith, J V

    1998-03-31

    Feldspar surfaces respond to chemical, biological, and mechanical weathering. The simplest termination is hydroxyl (OH), which interacts with any adsorption layer. Acid leaching of alkalis and aluminum generated a silica-rich, nanometers-thick skin on certain feldspars. Natural K, Na-feldspars develop fragile surfaces as etch pits expand into micrometer honeycombs, possibly colonized by lichens. Most crystals have various irregular coats. Based on surface-catalytic processes in molecular sieve zeolites, I proposed that some natural feldspars lose weakly bonded Al-OH (aluminol) to yield surfaces terminated by strongly bonded Si-OH (silanol). This might explain why some old feldspar-bearing rocks weather slower than predicted from brief laboratory dissolution. Lack of an Al-OH infrared frequency from a feldspar surface is consistent with such a silanol-dominated surface. Raman spectra of altered patches on acid-leached albite correspond with amorphous silica rather than hydroxylated silica-feldspar, but natural feldspar may respond differently. The crystal structure of H-exchanged feldspar provides atomic positions for computer modeling of complex ideas for silica-terminated feldspar surfaces. Natural weathering also depends on swings of temperature and hydration, plus transport of particles, molecules, and ionic complexes by rain and wind. Soil formation might be enhanced by crushing granitic outcrops to generate new Al-rich surfaces favorable for chemical and biological weathering. Ornamental slabs used by architects and monumental masons might last longer by minimizing mechanical abrasion during sawing and polishing and by silicifying the surface. Silica-terminated feldspar might be a promising ceramic surface.

  13. Current Understanding of Cu-Exchanged Chabazite Molecular Sieves for Use as Commercial Diesel Engine DeNOx Catalysts

    SciTech Connect

    Gao, Feng; Kwak, Ja Hun; Szanyi, Janos; Peden, Charles HF

    2013-11-03

    Selective catalytic reduction (SCR) of NOx with ammonia using metal-exchanged molecular sieves with a chabazite (CHA) structure has recently been commercialized on diesel vehicles. One of the commercialized catalysts, i.e., Cu-SSZ-13, has received much attention for both practical and fundamental studies. For the latter, the particularly well-defined structure of this zeolite is allowing long-standing issues of the catalytically active site for SCR in metal-exchanged zeolites to be addressed. In this review, recent progress is summarized with a focus on two areas. First, the technical significance of Cu-SSZ-13 as compared to other Cu-ion exchanged zeolites (e.g., Cu-ZSM-5 and Cu-beta) is highlighted. Specifically, the much enhanced hydrothermal stability for Cu-SSZ-13 compared to other zeolite catalysts is addressed via performance measurements and catalyst characterization using several techniques. The enhanced stability of Cu-SSZ-13 is rationalized in terms of the unique small pore structure of this zeolite catalyst. Second, the fundamentals of the catalytically active center; i.e., the chemical nature and locations within the SSZ-13 framework are presented with an emphasis on understanding structure-function relationships. For the SCR reaction, traditional kinetic studies are complicated by intra-particle diffusion limitations. However, a major side reaction, nonselective ammonia oxidation by oxygen, does not suffer from mass-transfer limitations at relatively low temperatures due to significantly lower reaction rates. This allows structure-function relationships that are rather well understood in terms of Cu ion locations and redox properties. Finally, some aspects of the SCR reaction mechanism are addressed on the basis of in-situ spectroscopic studies.

  14. Synthesis and modification of mesoporous silica and the preparation of molecular sieve thin films via pulsed laser deposition

    NASA Astrophysics Data System (ADS)

    Coutinho, Decio Heringer

    2001-07-01

    describes the evaluation of the HISIV(TM) 1000 molecular sieve for TBC adsorption. The TBC equilibrium capacity was determined from a cyclohexane/TBC liquid mixture and was comparable to alumina adsorbents. Practicum One. A fluorescent diagnostic system was developed to image the inhomogeneous mixture formed as two miscible fluids mix. This diagnostic for the mixing fraction uses a commercially available CCD color camera, a polarity sensitive fluorescent probe (DCM), and the planar laser induced fluorescence (PLIF) imaging technique to track the mixing of two miscible fluids of different polarity (ethanol and decane). The DCM fluorescence spectrum shifts to the red with increasing polarity, and the CCD camera's red, green, and blue color channels serve as spectral filters for the probe's fluorescence.

  15. Dark- and photoreactions of ethanol and acetaldehyde over TiO{sub 2}/carbon molecular sieve fibers

    SciTech Connect

    Reztsova, T.; Chang, C.H.; Idriss, H.; Koresh, J.

    1999-07-01

    TiO{sub 2} has been synthesized within the pores of carbon molecular sieve fibers (CMSF) in order to grow particles of quantum size. TiO{sub 2}/CMSF characteristics were followed by X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), and UV-vis diffuse reflectance. XPS showed that all Ti cations are in a +4 oxidation state. The reduction profile of Ti cations (made by preferential O anion removal due to Ar{sup +} sputtering), as evidenced by Ti{sup +x}/Ti{sup +4} cations, is very similar to that already observed for well-defined TiO{sub 2} surfaces. The absence of XRD pattern indicated that TiO{sub 2} particles are in an amorphous form. UV-vis diffuse reflectance showed a considerably blue shift ({Delta}E = 0.6--0.7 eV) of the band gap of TiO{sub 2}/CMSF when compared to TiO{sub 2} (anatase). This shift translates an average particle radius of 15 {+-} 2 {angstrom}. Larger TiO{sub 2} particles, outside the CMSF nanopores, are, however, observed by TEM. Dark- and photoreactions of ethanol and acetaldehyde have been investigated over TiO{sub 2}/CMSF by steady state kinetics and temperature programmed desorption in UHV conditions, as well as in batch conditions at atmospheric pressure. UHV-steady state ethanol reactions have shown eightfold increase in the reaction rate at 573 K in the presence of UV when compared to dark reactions at the same temperatures. The rate constants ratio k{sub 2}K{sub 2}/k{sub 1}K{sub 1}, for the photoreactions of ethanol, is ca. 40 times higher for TiO{sub 2}/CMSF than for TiO{sub 2} (powder) indicating the high selectivity of the former toward total conversion of ethanol to CO{sub 2} with minor accumulation of acetaldehyde (k{sub 1}K{sub 1} and k{sub 2}K{sub 2} are the rate constants for ethanol to acetaldehyde and acetaldehyde to CO{sub 2}, respectively). Evidence of C-C bond dissociation is given by formaldehyde desorption during UV-acetaldehyde-TPD over TiO{sub 2}/CMSF under UHV conditions. Moreover, UV

  16. Evaluation of INL Supplied MOOSE/OSPREY Model: Modeling Water Adsorption on Type 3A Molecular Sieve

    SciTech Connect

    Pompilio, L. M.; DePaoli, D. W.; Spencer, B. B.

    2014-08-29

    The purpose of this study was to evaluate Idaho National Lab’s Multiphysics Object-Oriented Simulation Environment (MOOSE) software in modeling the adsorption of water onto type 3A molecular sieve (3AMS). MOOSE can be thought-of as a computing framework within which applications modeling specific coupled-phenomena can be developed and run. The application titled Off-gas SeParation and REcoverY (OSPREY) has been developed to model gas sorption in packed columns. The sorbate breakthrough curve calculated by MOOSE/OSPREY was compared to results previously obtained in the deep bed hydration tests conducted at Oak Ridge National Laboratory. The coding framework permits selection of various options, when they exist, for modeling a process. For example, the OSPREY module includes options to model the adsorption equilibrium with a Langmuir model or a generalized statistical thermodynamic adsorption (GSTA) model. The vapor solid equilibria and the operating conditions of the process (e.g., gas phase concentration) are required to calculate the concentration gradient driving the mass transfer between phases. Both the Langmuir and GSTA models were tested in this evaluation. Input variables were either known from experimental conditions, or were available (e.g., density) or were estimated (e.g., thermal conductivity of sorbent) from the literature. Variables were considered independent of time, i.e., rather than having a mass transfer coefficient that varied with time or position in the bed, the parameter was set to remain constant. The calculated results did not coincide with data from laboratory tests. The model accurately estimated the number of bed volumes processed for the given operating parameters, but breakthrough times were not accurately predicted, varying 50% or more from the data. The shape of the breakthrough curves also differed from the experimental data, indicating a much wider sorption band. Model modifications are needed to improve its utility and

  17. Activation and micropore structure determination of carbon-fiber composite molecular sieves. Topical report, 30 March 1994--14 April 1995

    SciTech Connect

    Jagtoyen, M.; Derbyshire, F.; Kimber, G.; Fei, You Qing

    1995-05-19

    Progress in developing novel, rigid, monolithic adsorbent carbon fiber composites is described. Carbon fiber composites are activated using steam or CO{sub 2}, in order to produce uniform activation through the material and to control the pore structure and adsorptive properties. There is an overall shrinkage during activation, which is directly correlated with burnoff; burnoff above 40% results in fracture. Burnoffs higher than 10% does not produce any benefit for separation of CH{sub 4}-CO{sub 2} mixtures. Five samples of CFCMS have been prepared for testing as molecular sieves; all have relatively narrow pore size distributions with average pore diameters around 6A.

  18. Low temperature VOC combustion over manganese, Cobalt and Zinc ALPO(4) Molecular sieves. Semi-annual, March 1, 1996 - Aug. 31, 1996

    SciTech Connect

    Das, K.; Sheehan, D.G.; Szostak, R.

    1996-12-31

    A functional fixed bed continuous flow catalytic reactor was constructed for conducting experiments on the catalytic destruction of VOCs using cobalt and manganese containing aluminophosphate catalysts (MeAPOs). The reactor was also interfaced to a Gas Chromatograph in order to facilitate on line product analysis. As preliminary catalytic experiments, a cobalt exchanged form of large pore zeolite Y was used as a reference catalyst for the oxidation of methylene chloride (CH{sub 2}Cl{sub 2}). At 350{degrees}C, the catalyst was effective in partial conversion of this feed stream of VOC to CO{sub 2}. Optimization of reaction conditions are currently underway in order to obtain higher conversion levels. The effect of variations in reaction conditions such as reactant flow rate, reaction temperature and catalyst compositions are currently been investigated. In the next phase of this project, the Co-exchanged Y zeolite will be substituted by the MeAPOs catalysts and the reactivities of the latter will be assessed. The potential of the MeAPOs to function as oxidation catalysts was evaluated in the liquid phase conversion of phenol to hydroquinone and catechol. The percentage conversion and product yield were significant and varied depending on the metal type and content of the molecular sieve framework. Conversion levels were also dependent on molecular sieve pore dimensions as the medium pore MeAPO-11 was more active than the larger pore MeAPO-5 or MeAPO-36.

  19. Molecular analysis of the bovine anaphylatoxin C5a receptor

    PubMed Central

    Nemali, Sailasree; Siemsen, Daniel W.; Nelson, Laura K.; Bunger, Peggy L.; Faulkner, Craig L.; Rainard, Pascal; Gauss, Katherine A.; Jutila, Mark A.; Quinn, Mark T.

    2008-01-01

    Recruitment of phagocytes to inflammatory sites involves the coordinated action of several chemoattractants, including the anaphylatoxin C5a. While the C5a receptor (C5aR) has been well characterized in humans and rodents, little is known about the bovine C5aR. Here, we report cloning of bovine C5R1, the gene encoding bovine C5aR. We also analyzed genomic sequence upstream of the C5R1 translation start site. Although the bovine C5aR amino acid sequence was well conserved among species, significant differences in conserved features were found, including major differences in the N terminus, intracellular loop 3, and transmembrane domain VII. Analysis of C5aR expression by flow cytometry and confocal microscopy demonstrated high levels of C5aR on all bovine neutrophils and a subset of bovine monocytes. C5aR was not expressed on resting or activated bovine lymphocytes, although C5aR message was present in these cells. C5aR was also expressed on a small subset of bovine mammary epithelial cells. Pharmacological analysis of bovine C5aR-mediated responses showed that bovine C5a and C5adesArg both induced dose-dependent calcium fluxes and chemotaxis in bovine neutrophils, with similar efficacy for both agonists. Treatment of bovine neutrophils with C5a or C5adesArg resulted in homologous desensitization of bovine C5aR and cross-desensitization to interleukin 8 (IL-8) and platelet-activating factor (PAF); whereas, treatment with IL-8 or PAF did not cross-desensitize the cells to C5a or C5adesArg. Overall, these studies provide important information regarding distinct structural and functional features that may contribute to the unique pharmacological properties of bovine C5aR. PMID:18480166

  20. Integrated Testing of a 4-Bed Molecular Sieve and a Temperature-Swing Adsorption Compressor for Closed-Loop Air Revitalization

    NASA Technical Reports Server (NTRS)

    Knox, James C.; Mulloth, Lila M.; Affleck, David L.

    2004-01-01

    Accumulation and subsequent compression of carbon dioxide that is removed from space cabin are two important processes involved in a closed-loop air revitalization scheme of the International Space Station (ISS). The 4-Bed Molecular Sieve (4BMS) of ISS currently operates in an open loop mode without a compressor. This paper reports the integrated 4BMS and liquid-cooled TSAC testing conducted during the period of March 3 to April 18, 2003. The TSAC prototype was developed at NASA Ames Research Center (ARC). The 4BMS was modified to a functionally flight-like condition at NASA Marshall Space Flight Center (MSFC). Testing was conducted at MSFC. The paper provides details of the TSAC operation at various CO2 loadings and corresponding performance of CDRA.

  1. Nanoscopic imaging of meso-tetraalkylporphyrins prepared in high yields enabled by Montmorrilonite K10 and 3A molecular sieves.

    PubMed

    Plamont, Rémi; Kikkawa, Yoshihiro; Takahashi, Mayuko; Kanesato, Masatoshi; Giorgi, Michel; Chan Kam Shun, Anita; Roussel, Christian; Balaban, Teodor Silviu

    2013-08-19

    We have developed a high-yielding synthesis of meso-tetraalkylporphyrins, which previously have been obtained only in lower yields. By employing Montmorrilonite K10 as the acid catalyst and 3 Å molecular sieves as the dehydrating agent, yields that reached 70 % could be achieved with some aliphatic aldehydes. The free-base porphyrins with decyl (C10) or longer chains were imaged at the single-molecule level at the solvent/surface interface. Highly oriented pyrolytic graphite (HOPG) was used as a π-stacking surface, whereas 1-phenyloctane and 1-phenylnonane were used as solvents. An odd-even effect was observed from C13 to C16. For C13 a single-crystal X-ray structure allowed an unprecedented insight into how packing from two dimensions is expanded into a three-dimensional crystal lattice. PMID:23839774

  2. Natural gas cleanup: Evaluation of a molecular sieve carbon as a pressure swing adsorbent for the separation of methane/nitrogen mixtures

    SciTech Connect

    Grimes, R.W.

    1994-06-01

    This report describes the results of a preliminary evaluation to determine the technical feasibility of using a molecular sieve carbon manufactured by the Takeda Chemical Company of Japan in a pressure owing adsorption cycle for upgrading natural gas (methane) contaminated with nitrogen. Adsorption tests were conducted using this adsorbent in two, four, and five-step adsorption cycles. Separation performance was evaluated in terms of product purity, product recovery, and sorbent productivity for all tests. The tests were conducted in a small, single-column adsorption apparatus that held 120 grams of the adsorbent. Test variables included adsorption pressure, pressurization rate, purge rate and volume, feed rate, and flow direction in the steps from which the product was collected. Sorbent regeneration was accomplished by purging the column with the feed gas mixture for all but one test series where a pure methane purge was used. The ratio between the volumes of the pressurization gas and the purge gas streams was found to be an important factor in determining separation performance. Flow rates in the various cycle steps had no significant effect. Countercurrent flow in the blow-down and purge steps improved separation performance. Separation performance appears to improve with increasing adsorption pressure, but because there are a number of interrelated variables that are also effected by pressure, further testing will be needed to verify this. The work demonstrates that a molecular sieve carbon can be used to separate a mixture of methane and nitrogen when used in a pressure swing cycle with regeneration by purge. Further work is needed to increase product purity and product recovery.

  3. OZONE REACTION WITH N-ALDEHYDES (N=4-10), BENZALDEHYDE, ETHANOL, ISOPROPANOL, AND N-PROPANOL ADSORBED ON A DUAL-BED GRAPHITIZED CARBON/CARBON MOLECULAR SIEVE ADSORBENT CARTRIDGE

    EPA Science Inventory

    Ozone reacts with n-aldehydes (n = 4 - 10), benzaldehyde, ethanol, isopropanol, and n-propanol adsorbed on a dual-bed graphitized carbon/carbon molecular sieve adsorbent cartridge. Destruction of n-aldehydes increases with n number and with ozone concentration. In some samp...

  4. Massively parallel mathematical sieves

    SciTech Connect

    Montry, G.R.

    1989-01-01

    The Sieve of Eratosthenes is a well-known algorithm for finding all prime numbers in a given subset of integers. A parallel version of the Sieve is described that produces computational speedups over 800 on a hypercube with 1,024 processing elements for problems of fixed size. Computational speedups as high as 980 are achieved when the problem size per processor is fixed. The method of parallelization generalizes to other sieves and will be efficient on any ensemble architecture. We investigate two highly parallel sieves using scattered decomposition and compare their performance on a hypercube multiprocessor. A comparison of different parallelization techniques for the sieve illustrates the trade-offs necessary in the design and implementation of massively parallel algorithms for large ensemble computers.

  5. Effect of surfactant/silica molar ratios on the formation of mesoporous molecular sieves: Inorganic mimicry of surfactant liquid-crystal phases and mechanistic implications

    SciTech Connect

    Vartuli, J.C.; Schmitt, K.D.; McCullen, S.B.; Hellring, S.D.; Beck, J.S.; Schlenker, J.L.; Olson, D.H.; Sheppard, E.W.; Kresge, C.T.; Roth, W.J.

    1994-12-01

    The influence of surfactant/silica molar ratio (Sur/Si) in the synthesis of mesoporous molecular sieve materials (M41S) was studied in a simple ternary synthesis system containing tetraethylorthosilicate (TEOS), water, and the cetyltrimethylammonium (CTMA) cation at 100{degrees}C. The resulting silicate materials were characterized by X-ray diffraction, {sup 29}Si NMR, and FTIR. As the Sur/Si molar ratio increased from 0.5 to 2, the siliceous products obtained could be classified into four separate groups: MCM-41 (hexagonal), MCM-48 (cubic), thermally unstable M41S, and a molecular species, the cubic octamer [(CTMA)SiO{sub 2.5}]{sub 8}. One of the thermally unstable structures has been identified as a lamellar phase. These results are consistent with known micellar phase transformations that occur at various surfactant concentrations and reinforce the concept that liquid-crystal structures serve as templating agents for the formation of M41S type materials. 48 refs., 13 figs., 5 tabs.

  6. Synthesis and application of mesoporous molecular sieve for miniaturized matrix solid-phase dispersion extraction of bioactive flavonoids from toothpaste, plant, and saliva.

    PubMed

    Cao, Wan; Cao, Jun; Ye, Li-Hong; Xu, Jing-Jing; Hu, Shuai-Shuai; Peng, Li-Qing

    2015-12-01

    This article describes the use of the mesoporous molecular sieve KIT-6 as a sorbent in miniaturized matrix solid-phase dispersion (MSPD) in combination with ultra-performance LC for the determination of bioactive flavonoids in toothpaste, Scutellariae Radix, and saliva. In this study, for the first time, KIT-6 was used as a sorbent material for this mode of extraction. Compared with common silica-based sorbents (C18 and activated silica gel), the proposed KIT-6 dispersant with a three-dimensional cubic Ia3d structure and highly ordered arrays of mesoporous channels exhibits excellent adsorption capability of the tested compounds. In addition, several experimental variables, such as the mass ratio of sample to dispersant, grinding time, and elution solvent, were optimized to maximize the extraction efficiency. The proposed analytical method is simple, fast, and entails low consumption of samples, dispersants and elution solvents, thereby meeting "green chemistry" requirements. Under the optimized conditions, the recoveries of three bioactive flavonoids obtained by analyzing the spiked samples were from 89.22 to 101.17%. Also, the LODs and LOQs for determining the analytes were in the range of 0.02-0.04 μg/mL and 0.07-0.13 μg/mL, respectively. Finally, the miniaturized matrix solid-phase dispersion method was successfully applied to the analysis of target solutes in real samples, and satisfactory results were obtained. PMID:26332895

  7. Application of computational fluid dynamics for the simulation of cryogenic molecular sieve bed absorber of hydrogen isotopes recovery system for Indian LLCB-TBM

    SciTech Connect

    Gayathri Devi, V.; Sircar, A.; Sarkar, B.

    2015-03-15

    One of the most challenging tasks in the design of the fuel cycle system lies in the effective design of Tritium Extraction System (TES) which involves proper extraction and purification of tritium in the fuel cycle of the fusion reactor. Indian Lead Lithium cooled Ceramic Breeder Test Blanket Module (LLCB-TBM) would extract hydrogen isotopes through Cryogenic Molecular Sieve Bed (CMSB) adsorber system. A prototype Hydrogen Isotopes Recovery System (HIRS) is being developed to validate the concepts for tritium extraction by adsorption mass transfer mechanism. In this study, a design model has been developed and analyzed to simulate the adsorption mass transfer kinetics in a fixed bed adsorption column. The simulation leads primarily to effective design of HIRS, which is a state-of-the-art technology. The paper describes the process simulation approach and the results of Computational Fluid Dynamics (CFD) analysis. The effects of different operating conditions are studied to investigate their influence on the hydrogen isotopes adsorption capacity. The results of the present simulation study would be used to understand the best optimized transport phenomenon before realizing the TES as a system for LLCB-TBM. (authors)

  8. Insight into the molecular switch mechanism of human Rab5a from molecular dynamics simulations

    SciTech Connect

    Wang, Jing-Fang; Chou, Kuo-Chen

    2009-12-18

    Rab5a is currently a most interesting target because it is responsible for regulating the early endosome fusion in endocytosis and possibly the budding process. We utilized longtime-scale molecular dynamics simulations to investigate the internal motion of the wild-type Rab5a and its A30P mutant. It was observed that, after binding with GTP, the global flexibility of the two proteins is increasing, while the local flexibility in their sensitive sites (P-loop, switch I and II regions) is decreasing. Also, the mutation of Ala30 to Pro30 can cause notable flexibility variations in the sensitive sites. However, this kind of variations is dramatically reduced after binding with GTP. Such a remarkable feature is mainly caused by the water network rearrangements in the sensitive sites. These findings might be of use for revealing the profound mechanism of the displacements of Rab5a switch regions, as well as the mechanism of the GDP dissociation and GTP association.

  9. Microfluidic sieve valves

    DOEpatents

    Quake, Stephen R; Marcus, Joshua S; Hansen, Carl L

    2015-01-13

    Sieve valves for use in microfluidic device are provided. The valves are useful for impeding the flow of particles, such as chromatography beads or cells, in a microfluidic channel while allowing liquid solution to pass through the valve. The valves find particular use in making microfluidic chromatography modules.

  10. Carbon fiber composite molecular sieves

    SciTech Connect

    Burchell, T.D.; Rogers, M.R.

    1997-12-01

    Monolithic adsorbents based on isotropic pitch fibers have been developed jointly by ORNL and the University of Kentucky, Center for Applied Energy Research. The monoliths are attractive for gas separation and storage applications because of their unique combination of physical properties and microporous structure. Currently at ORNL the monoliths are produced in billets that are 10 cm in diameter and 25 cm in length. The monolithic adsorbent material is being considered for guard bed applications on a natural gas (NG) powered device. In order for the material to be successful in this application, one must attain a uniform activation to modest micropore volumes throughout the large monoliths currently being produced. Here the authors report the results of a study directed toward attaining uniform activation in these billets.

  11. Research on Molecular Sieve Technology.

    ERIC Educational Resources Information Center

    Shah, Dhananjai B.; Hayhurst, David T.

    1985-01-01

    The zeolite synthesis and modification research program at Cleveland State University (Ohio) is described, including program philosophy and objectives, and research facilities. Also considers zeolite synthesis, adsorption on zeolites, kinetics of adsorption, and zeolite catalysis research. (JN)

  12. Ultrasound- and Molecular Sieves-Assisted Synthesis, Molecular Docking and Antifungal Evaluation of 5-(4-(Benzyloxy)-substituted phenyl)-3-((phenylamino)methyl)-1,3,4-oxadiazole-2(3H)-thiones.

    PubMed

    Nimbalkar, Urja D; Tupe, Santosh G; Seijas Vazquez, Julio A; Khan, Firoz A Kalam; Sangshetti, Jaiprakash N; Nikalje, Anna Pratima G

    2016-01-01

    A novel series of 5-(4-(benzyloxy)substituted phenyl)-3-((phenyl amino)methyl)-1,3,4-oxadiazole-2(3H)-thione Mannich bases 6a-o were synthesized in good yield from the key compound 5-(4-(benzyloxy)phenyl)-1,3,4-oxadiazole-2(3H)-thione by aminomethylation with paraformaldehyde and substituted amines using molecular sieves and sonication as green chemistry tools. The antifungal activity of the new products was evaluated against seven human pathogenic fungal strains, namely, Candida albicans ATCC 24433, Candida albicans ATCC 10231, Candida glabrata NCYC 388, Cryptococcus neoformans ATCC 34664, Cryptococcus neoformans PRL 518, Aspergillus fumigatus NCIM 902 and Aspergillus niger ATCC 10578. The synthesized compounds 6d, 6f, 6g, 6h and 6j exhibited promising antifungal activity against the tested fungal pathogens. In molecular docking studies, derivatives 6c, 6f and 6i showed good binding at the active site of C. albicans cytochrome P450 enzyme lanosterol 14 α-demethylase. The in vitro antifungal activity results and docking studies indicated that the synthesized compounds have potential antifungal activity and can be further optimized as privileged scaffolds to design and develop potent antifungal drugs. PMID:27171073

  13. Generalized Fibonacci photon sieves.

    PubMed

    Ke, Jie; Zhang, Junyong

    2015-08-20

    We successfully extend the standard Fibonacci zone plates with two on-axis foci to the generalized Fibonacci photon sieves (GFiPS) with multiple on-axis foci. We also propose the direct and inverse design methods based on the characteristic roots of the recursion relation of the generalized Fibonacci sequences. By switching the transparent and opaque zones, according to the generalized Fibonacci sequences, we not only realize adjustable multifocal distances but also fulfill the adjustable compression ratio of focal spots in different directions. PMID:26368763

  14. Leishmania donovani eukaryotic initiation factor 5A: molecular characterization, localization and homology modelling studies.

    PubMed

    Singh, Sushma; Raju, K; Jatekar, Deepika; Dinesh, Neeradi; Paul, M Stanley; Sobhia, M E

    2014-08-01

    Eukaryotic translation initiation factor 5A (eIF5A) is a small acidic protein highly conserved from archaea to mammals. eIF5A is the only protein which undergoes a unique lysine residue modification to hypusine. Hypusinylation is important for the function of eIF5A which is reported to be essential for cell viability. eIF5A promotes formation of the first peptide bond at the onset of protein synthesis. However, its function in Leishmania donovani is unclear. The present study focuses on the characterization and localization of L. donovani eIF5A protein. The eIF5A gene contains an ORF of 501×bp encoding 166 amino acid residues with a predicted molecular mass and isoelectric point of 17.8 kDa and 4.83 respectively. A phylogenetic tree analysis revealed its close proximity to trypanosomes however it is distantly located from Trichomonas vaginalis and Plasmodium falciparum. The L. donovani eIF5A was expressed as a 6× His tagged protein whose identity was confirmed by western blot and MALDI. Biophysical investigation by CD revealed the predominant presence of 49% β sheet structure which correlated well with secondary structure prediction. To gain insight into the role of eIF5A in L. donovani, we investigated the subcellular distribution of eIF5A. A GFP-fusion of L. donovani eIF5A was found to be localized in cytoplasm as confirmed by subcellular fractionation. Our studies indicated that eIF5A is primarily localized to cytoplasm and is undetectable in nuclear fraction. The homology model of eIF5A of L. donovani was built and the resulting model showed acceptable Ramachandran statistics. The model is reliable and can be used to study eIF5A binding with its effector molecules.

  15. The cardiomyocyte molecular clock, regulation of Scn5a, and arrhythmia susceptibility.

    PubMed

    Schroder, Elizabeth A; Lefta, Mellani; Zhang, Xiping; Bartos, Daniel C; Feng, Han-Zhong; Zhao, Yihua; Patwardhan, Abhijit; Jin, Jian-Ping; Esser, Karyn A; Delisle, Brian P

    2013-05-15

    The molecular clock mechanism underlies circadian rhythms and is defined by a transcription-translation feedback loop. Bmal1 encodes a core molecular clock transcription factor. Germline Bmal1 knockout mice show a loss of circadian variation in heart rate and blood pressure, and they develop dilated cardiomyopathy. We tested the role of the molecular clock in adult cardiomyocytes by generating mice that allow for the inducible cardiomyocyte-specific deletion of Bmal1 (iCSΔBmal1). ECG telemetry showed that cardiomyocyte-specific deletion of Bmal1 (iCSΔBmal1(-/-)) in adult mice slowed heart rate, prolonged RR and QRS intervals, and increased episodes of arrhythmia. Moreover, isolated iCSΔBmal1(-/-) hearts were more susceptible to arrhythmia during electromechanical stimulation. Examination of candidate cardiac ion channel genes showed that Scn5a, which encodes the principle cardiac voltage-gated Na(+) channel (Na(V)1.5), was circadianly expressed in control mouse and rat hearts but not in iCSΔBmal1(-/-) hearts. In vitro studies confirmed circadian expression of a human Scn5a promoter-luciferase reporter construct and determined that overexpression of clock factors transactivated the Scn5a promoter. Loss of Scn5a circadian expression in iCSΔBmal1(-/-) hearts was associated with decreased levels of Na(V)1.5 and Na(+) current in ventricular myocytes. We conclude that disruption of the molecular clock in the adult heart slows heart rate, increases arrhythmias, and decreases the functional expression of Scn5a. These findings suggest a potential link between environmental factors that alter the cardiomyocyte molecular clock and factors that influence arrhythmia susceptibility in humans.

  16. Molecular modeling of the human eukaryotic translation initiation factor 5A (eIF5A) based on spectroscopic and computational analyses

    SciTech Connect

    Costa-Neto, Claudio M. . E-mail: claudio@fmrp.usp.br; Parreiras-e-Silva, Lucas T.; Ruller, Roberto; Oliveira, Eduardo B.; Miranda, Antonio; Oliveira, Laerte; Ward, Richard J.

    2006-09-01

    The eukaryotic translation initiation factor 5A (eIF5A) is a protein ubiquitously present in archaea and eukarya, which undergoes a unique two-step post-translational modification called hypusination. Several studies have shown that hypusination is essential for a variety of functional roles for eIF5A, including cell proliferation and synthesis of proteins involved in cell cycle control. Up to now neither a totally selective inhibitor of hypusination nor an inhibitor capable of directly binding to eIF5A has been reported in the literature. The discovery of such an inhibitor might be achieved by computer-aided drug design based on the 3D structure of the human eIF5A. In this study, we present a molecular model for the human eIF5A protein based on the crystal structure of the eIF5A from Leishmania brasiliensis, and compare the modeled conformation of the loop bearing the hypusination site with circular dichroism data obtained with a synthetic peptide of this loop. Furthermore, analysis of amino acid variability between different human eIF5A isoforms revealed peculiar structural characteristics that are of functional relevance.

  17. Itegrated Test and Evaluation of a 4-Bed Molecular Sieve (4BMS) Carbon Dioxide Removtal System (CDRA), Mechanical Compressor Engineering Development Unit (EDU), and Sabitier Engineering Development Unit (EDU)

    NASA Technical Reports Server (NTRS)

    Knox, James C.; Campbell, Melissa; Murdoch, Karen; Miller, Lee A.; Jeng, Frank

    2005-01-01

    Currently on the International Space Station s (ISS) U.S. Segment, carbon dioxide (CO2) scrubbed from the cabin by a 4-Bed Molecular Sieve (4BMS) Carbon Dioxide Removal Assembly (CDRA) is vented overboard as a waste product. Likewise, the product hydrogen (H2) that will be generated by the Oxygen Generation Assembly (OGA) planned for installation will also be vented. A flight experiment has been proposed that will take the waste CO2 removed from the cabin, and via the catalytic Sabatier process, reduce it with waste H2 to generate water and methane. The water produced may provide cost and logistics savings for ISS by reducing the amount of water periodically re-supplied to orbit. To make this concept viable, a mechanical piston compressor and accumulator were developed for collecting and storing the CO2 from the CDRA. The compressor, accumulator and Sabatier system would be packaged together as one unit and referred to as the Carbon Dioxide Reduction Assembly (CRA). Testing was required to evaluate the performance of a 4BMS CDRA, compressor, accumulator, and Sabatier performance along with their operating rules when integrated together. This had been numerically modeled and simulated; however, testing was necessary to verify the results from the engineering analyses. Testing also allowed a better understanding of the practical inefficiencies and control issues involved in a fully integrated system versus the theoretical ideals in the model. This paper presents and discusses the results of an integrated engineering development unit test.

  18. Clinical and molecular characterization of 40 patients with classic Ehlers–Danlos syndrome: identification of 18 COL5A1 and 2 COL5A2 novel mutations

    PubMed Central

    2013-01-01

    Background Classic Ehlers–Danlos syndrome (cEDS) is a rare autosomal dominant connective tissue disorder that is primarily characterized by skin hyperextensibility, abnormal wound healing/atrophic scars, and joint hypermobility. A recent study demonstrated that more than 90% of patients who satisfy all of these major criteria harbor a type V collagen (COLLV) defect. Methods This cohort included 40 patients with cEDS who were clinically diagnosed according to the Villefranche nosology. The flowchart that was adopted for mutation detection consisted of sequencing the COL5A1 gene and, if no mutation was detected, COL5A2 analysis. In the negative patients the presence of large genomic rearrangements in COL5A1 was investigated using MLPA, and positive results were confirmed via SNP-array analysis. Results We report the clinical and molecular characterization of 40 patients from 28 families, consisting of 14 pediatric patients and 26 adults. A family history of cEDS was present in 9 patients. The majority of the patients fulfilled all the major diagnostic criteria for cEDS; atrophic scars were absent in 2 females, skin hyperextensibility was not detected in a male and joint hypermobility was negative in 8 patients (20% of the entire cohort). Wide inter- and intra-familial phenotypic heterogeneity was observed. We identified causal mutations with a detection rate of approximately 93%. In 25/28 probands, COL5A1 or COL5A2 mutations were detected. Twenty-one mutations were in the COL5A1 gene, 18 of which were novel (2 recurrent). Of these, 16 mutations led to nonsense-mediated mRNA decay (NMD) and to COLLV haploinsufficiency and 5 mutations were structural. Two novel COL5A2 splice mutations were detected in patients with the most severe phenotypes. The known p. (Arg312Cys) mutation in the COL1A1 gene was identified in one patient with vascular-like cEDS. Conclusions Our findings highlight that the three major criteria for cEDS are useful and sufficient for cEDS clinical

  19. Multiprocessing the Sieve of Eratosthenes

    SciTech Connect

    Bokhari, S.H.

    1987-04-01

    More than two thousand years ago, Eratosthenes of Cyrene described a procedure for finding all prime numbers in a given range. This straightforward algorithm, known as the Sieve of Eratosthenes, is to this day the only procedure for finding prime numbers. In recent years it has been of interest to computer scientists and engineers because it serves as a convenient benchmark against which to measure some aspects of a computer's performance. Specifically, the Sieve tests the power of a machine (or of a compiler) to access a very large array in memory rapidly and repeatedly. This power is clearly influenced by memory access time, the speed at which indexing is done, and the overhead of looping. The parallel version of the Sieve is very useful as a test of some of the capabilities of a parallel machine. The parallel algorithm is straightforward, and so is the process for checking the final results. However, the efficient implementation of the algorithm on a real parallel machine, especially in the dynamic load-balancing case, requires thoughtful design.

  20. Molecular Mechanism of SLC5A8 Inactivation in Breast Cancer

    PubMed Central

    Elangovan, Selvakumar; Pathania, Rajneesh; Ramachandran, Sabarish; Ananth, Sudha; Padia, Ravi N.; Srinivas, Sonne R.; Babu, Ellappan; Hawthorn, Lesleyann; Schoenlein, Patricia V.; Boettger, Thomas; Smith, Sylvia B.; Prasad, Puttur D.; Ganapathy, Vadivel

    2013-01-01

    SLC5A8 is a putative tumor suppressor that is inactivated in more than 10 different types of cancer, but neither the oncogenic signaling responsible for SLC5A8 inactivation nor the functional relevance of SLC5A8 loss to tumor growth has been elucidated. Here, we identify oncogenic HRAS (HRASG12V) as a potent mediator of SLC5A8 silencing in human nontransformed normal mammary epithelial cell lines and in mouse mammary tumors through DNMT1. Further, we demonstrate that loss of Slc5a8 increases cancer-initiating stem cell formation and promotes mammary tumorigenesis and lung metastasis in an HRAS-driven murine model of mammary tumors. Mammary-gland-specific overexpression of Slc5a8 (mouse mammary tumor virus-Slc5a8 transgenic mice), as well as induction of endogenous Slc5a8 in mice with inhibitors of DNA methylation, protects against HRAS-driven mammary tumors. Collectively, our results provide the tumor-suppressive role of SLC5A8 and identify the oncogenic HRAS as a mediator of tumor-associated silencing of this tumor suppressor in mammary glands. These findings suggest that pharmacological approaches to reactivate SLC5A8 expression in tumor cells have potential as a novel therapeutic strategy for breast cancer treatment. PMID:23918800

  1. Preparation of amorphous sulfide sieves

    DOEpatents

    Siadati, Mohammad H.; Alonso, Gabriel; Chianelli, Russell R.

    2006-11-07

    The present invention involves methods and compositions for synthesizing catalysts/porous materials. In some embodiments, the resulting materials are amorphous sulfide sieves that can be mass-produced for a variety of uses. In some embodiments, methods of the invention concern any suitable precursor (such as thiomolybdate salt) that is exposed to a high pressure pre-compaction, if need be. For instance, in some cases the final bulk shape (but highly porous) may be same as the original bulk shape. The compacted/uncompacted precursor is then subjected to an open-flow hot isostatic pressing, which causes the precursor to decompose and convert to a highly porous material/catalyst.

  2. A patterned anisotropic nanofluidic sieving structure for continuous-flow separation of DNA and proteins.

    PubMed

    Fu, Jianping; Schoch, Reto B; Stevens, Anna L; Tannenbaum, Steven R; Han, Jongyoon

    2007-02-01

    Microfabricated regular sieving structures hold great promise as an alternative to gels to improve the speed and resolution of biomolecule separation. In contrast to disordered porous gel networks, these regular structures also provide well defined environments ideal for the study of molecular dynamics in confining spaces. However, the use of regular sieving structures has, to date, been limited to the separation of long DNA molecules, however separation of smaller, physiologically relevant macromolecules, such as proteins, still remains a challenge. Here we report a microfabricated anisotropic sieving structure consisting of a two-dimensional periodic nanofluidic filter array. The designed structural anisotropy causes different-sized or -charged biomolecules to follow distinct trajectories, leading to efficient separation. Continuous-flow size-based separation of DNA and proteins, as well as electrostatic separation of proteins, was achieved, demonstrating the potential use of this device as a generic molecular sieving structure for an integrated biomolecule sample preparation and analysis system. PMID:18654231

  3. A patterned anisotropic nanofluidic sieving structure for continuous-flow separation of DNA and proteins

    NASA Astrophysics Data System (ADS)

    Fu, Jianping; Schoch, Reto B.; Stevens, Anna L.; Tannenbaum, Steven R.; Han, Jongyoon

    2007-02-01

    Microfabricated regular sieving structures hold great promise as an alternative to gels to improve the speed and resolution of biomolecule separation. In contrast to disordered porous gel networks, these regular structures also provide well defined environments ideal for the study of molecular dynamics in confining spaces. However, the use of regular sieving structures has, to date, been limited to the separation of long DNA molecules, however separation of smaller, physiologically relevant macromolecules, such as proteins, still remains a challenge. Here we report a microfabricated anisotropic sieving structure consisting of a two-dimensional periodic nanofluidic filter array. The designed structural anisotropy causes different-sized or -charged biomolecules to follow distinct trajectories, leading to efficient separation. Continuous-flow size-based separation of DNA and proteins, as well as electrostatic separation of proteins, was achieved, demonstrating the potential use of this device as a generic molecular sieving structure for an integrated biomolecule sample preparation and analysis system.

  4. Molecular evolution of the cytochrome c oxidase subunit 5A gene in primates

    PubMed Central

    2008-01-01

    Background Many electron transport chain (ETC) genes show accelerated rates of nonsynonymous nucleotide substitutions in anthropoid primate lineages, yet in non-anthropoid lineages the ETC proteins are typically highly conserved. Here, we test the hypothesis that COX5A, the ETC gene that encodes cytochrome c oxidase subunit 5A, shows a pattern of anthropoid-specific adaptive evolution, and investigate the distribution of this protein in catarrhine brains. Results In a dataset comprising 29 vertebrate taxa, including representatives from all major groups of primates, there is nearly 100% conservation of the COX5A amino acid sequence among extant, non-anthropoid placental mammals. The most recent common ancestor of these species lived about 100 million years (MY) ago. In contrast, anthropoid primates show markedly elevated rates of nonsynonymous evolution. In particular, branch site tests identify five positively selected codons in anthropoids, and ancestral reconstructions infer that substitutions in these codons occurred predominantly on stem lineages (anthropoid, ape and New World monkey) and on the human terminal branch. Examination of catarrhine brain samples by immunohistochemistry characterizes for the first time COX5A protein distribution in the primate neocortex, and suggests that the protein is most abundant in the mitochondria of large-size projection neurons. Real time quantitative PCR supports previous microarray results showing COX5A is expressed in cerebral cortical tissue at a higher level in human than in chimpanzee or gorilla. Conclusion Taken together, these results suggest that both protein structural and gene regulatory changes contributed to COX5A evolution during humankind's ancestry. Furthermore, these findings are consistent with the hypothesis that adaptations in ETC genes contributed to the emergence of the energetically expensive anthropoid neocortex. PMID:18197981

  5. COL5A1 haploinsufficiency is a common molecular mechanism underlying the classical form of EDS.

    PubMed Central

    Wenstrup, R J; Florer, J B; Willing, M C; Giunta, C; Steinmann, B; Young, F; Susic, M; Cole, W G

    2000-01-01

    We have identified haploinsufficiency of the COL5A1 gene that encodes the proalpha1(V) chain of type V collagen in the classical form of the Ehlers-Danlos syndrome (EDS), a heritable connective-tissue disorder that severely alters the collagen-fibrillar structure of the dermis, joints, eyes, and blood vessels. Eight of 28 probands with classical EDS who were heterozygous for expressed polymorphisms in COL5A1 showed complete or nearly complete loss of expression of one COL5A1 allele. Reduced levels of proalpha1(V) mRNA relative to the levels of another type V collagen mRNA, proalpha2(V), were also observed in the cultured fibroblasts from EDS probands. Products of the two COL5A1 alleles were approximately equal after the addition of cycloheximide to the fibroblast cultures. After harvesting of mRNAs from cycloheximide-treated cultured fibroblasts, heteroduplex analysis of overlapping reverse transcriptase-PCR segments spanning the complete proalpha1(V) cDNA showed anomalies in four of the eight probands that led to identification of causative mutations, and, in the remaining four probands, targeting of CGA-->TGA mutations in genomic DNA revealed a premature stop at codon in one of them. We estimate that approximately one-third of individuals with classical EDS have mutations of COL5A1 that result in haploinsufficiency. These findings indicate that the normal formation of the heterotypic collagen fibrils that contain types I, III, and V collagen requires the expression of both COL5A1 alleles. PMID:10777716

  6. Multiprocessing the Sieve of Eratosthenes

    NASA Technical Reports Server (NTRS)

    Bokhari, S.

    1986-01-01

    The Sieve of Eratosthenes for finding prime numbers in recent years has seen much use as a benchmark algorithm for serial computers while its intrinsically parallel nature has gone largely unnoticed. The implementation of a parallel version of this algorithm for a real parallel computer, the Flex/32, is described and its performance discussed. It is shown that the algorithm is sensitive to several fundamental performance parameters of parallel machines, such as spawning time, signaling time, memory access, and overhead of process switching. Because of the nature of the algorithm, it is impossible to get any speedup beyond 4 or 5 processors unless some form of dynamic load balancing is employed. We describe the performance of our algorithm with and without load balancing and compare it with theoretical lower bounds and simulated results. It is straightforward to understand this algorithm and to check the final results. However, its efficient implementation on a real parallel machine requires thoughtful design, especially if dynamic load balancing is desired. The fundamental operations required by the algorithm are very simple: this means that the slightest overhead appears prominently in performance data. The Sieve thus serves not only as a very severe test of the capabilities of a parallel processor but is also an interesting challenge for the programmer.

  7. DAMBE5: a comprehensive software package for data analysis in molecular biology and evolution.

    PubMed

    Xia, Xuhua

    2013-07-01

    Since its first release in 2001 as mainly a software package for phylogenetic analysis, data analysis for molecular biology and evolution (DAMBE) has gained many new functions that may be classified into six categories: 1) sequence retrieval, editing, manipulation, and conversion among more than 20 standard sequence formats including MEGA, NEXUS, PHYLIP, GenBank, and the new NeXML format for interoperability, 2) motif characterization and discovery functions such as position weight matrix and Gibbs sampler, 3) descriptive genomic analysis tools with improved versions of codon adaptation index, effective number of codons, protein isoelectric point profiling, RNA and protein secondary structure prediction and calculation of minimum folding energy, and genomic skew plots with optimized window size, 4) molecular phylogenetics including sequence alignment, testing substitution saturation, distance-based, maximum parsimony, and maximum-likelihood methods for tree reconstructions, testing the molecular clock hypothesis with either a phylogeny or with relative-rate tests, dating gene duplication and speciation events, choosing the best-fit substitution models, and estimating rate heterogeneity over sites, 5) phylogeny-based comparative methods for continuous and discrete variables, and 6) graphic functions including secondary structure display, optimized skew plot, hydrophobicity plot, and many other plots of amino acid properties along a protein sequence, tree display and drawing by dragging nodes to each other, and visual searching of the maximum parsimony tree. DAMBE features a graphic, user-friendly, and intuitive interface and is freely available from http://dambe.bio.uottawa.ca (last accessed April 16, 2013).

  8. DAMBE5: a comprehensive software package for data analysis in molecular biology and evolution.

    PubMed

    Xia, Xuhua

    2013-07-01

    Since its first release in 2001 as mainly a software package for phylogenetic analysis, data analysis for molecular biology and evolution (DAMBE) has gained many new functions that may be classified into six categories: 1) sequence retrieval, editing, manipulation, and conversion among more than 20 standard sequence formats including MEGA, NEXUS, PHYLIP, GenBank, and the new NeXML format for interoperability, 2) motif characterization and discovery functions such as position weight matrix and Gibbs sampler, 3) descriptive genomic analysis tools with improved versions of codon adaptation index, effective number of codons, protein isoelectric point profiling, RNA and protein secondary structure prediction and calculation of minimum folding energy, and genomic skew plots with optimized window size, 4) molecular phylogenetics including sequence alignment, testing substitution saturation, distance-based, maximum parsimony, and maximum-likelihood methods for tree reconstructions, testing the molecular clock hypothesis with either a phylogeny or with relative-rate tests, dating gene duplication and speciation events, choosing the best-fit substitution models, and estimating rate heterogeneity over sites, 5) phylogeny-based comparative methods for continuous and discrete variables, and 6) graphic functions including secondary structure display, optimized skew plot, hydrophobicity plot, and many other plots of amino acid properties along a protein sequence, tree display and drawing by dragging nodes to each other, and visual searching of the maximum parsimony tree. DAMBE features a graphic, user-friendly, and intuitive interface and is freely available from http://dambe.bio.uottawa.ca (last accessed April 16, 2013). PMID:23564938

  9. Effect of H{sub 3}PW{sub 12}O{sub 40} impregnation on Sn-MCM-41 mesoporous molecular sieves and their physico-chemical properties

    SciTech Connect

    Nedumaran, D.; Pandurangan, A.

    2015-01-15

    Graphical abstract: The wide angle XRD shows the well dispersion of HPWA in Sn-MCM-41. It enhances the total acidity of the material. The acidity of the material is correlated with sulfone selectivity. The FT-IR of dibenzothiophene and product shows the formation of sulfone (DBTO{sub 2}). - Highlights: • To enhance the total acidity of Sn-MCM-41 TPA is impregnated. • FT-IR and {sup 31}P MAS NMR confirms the HPWA intact on Sn-MCM-41. • EDAX shows the presence of W and P on Sn-MCM-41. • In ODS formation of sulfone was confirmed by FT-IR and {sup 1}H NMR. • The order of the catalytic activity of the catalysts are 18HSnM > 28HSnM > 8HSnM. - Abstract: Si-Sn-MCM-41 (Si/Sn = 110) mesoporous molecular sieve was synthesized by hydrothermal sol–gel method using cetyltrimethylammonium bromide (CTAB) as surfactant and SnCl{sub 4}·5H{sub 2}O as a metal source. To generate surface acidity of Si-Sn-MCM-41, 12-tungstophosphoric acid (HPWA) is impregnated on it. The acidity of HPWA loading on Sn-MCM-41 was investigated by temperature programmed desorption of NH{sub 3}. The diffused reflectance spectra of ultraviolet radiation, Raman spectra, FT-IR, {sup 29}Si-MAS NMR and {sup 31}P-MAS NMR techniques revealed the intact of α-Keggin anions on Sn-MCM-41. The wide angle XRD results showed that the HPWA is well dispersed on the support. The total acidity was enhanced with increase in loading of H{sub 3}PW{sub 12}O{sub 40}. The catalytic activity was examined in desulfurization of dibenzothiophene in vapor phase system. Among the catalysts 18% HPWA loaded Sn-MCM-41 showed good catalytic activity in desulfurization at 325 °C. The HPWA/Sn-MCM-41 are a suitable solid acid catalyst for converting organic sulfur into insoluble sulfone.

  10. Mechanical sieve for screening mineral samples

    NASA Technical Reports Server (NTRS)

    Otto, W. P.

    1970-01-01

    Mechanical sieve consists of three horizontal screens mounted in a vertical stack. A combination of rotation and tapping produces an even flow across the screens, dislodges trapped particles, an ensures rapid segregation of the sample.

  11. Modeling the hydrodynamics of Phloem sieve plates.

    PubMed

    Jensen, Kaare Hartvig; Mullendore, Daniel Leroy; Holbrook, Noel Michele; Bohr, Tomas; Knoblauch, Michael; Bruus, Henrik

    2012-01-01

    Sieve plates have an enormous impact on the efficiency of the phloem vascular system of plants, responsible for the distribution of photosynthetic products. These thin plates, which separate neighboring phloem cells, are perforated by a large number of tiny sieve pores and are believed to play a crucial role in protecting the phloem sap from intruding animals by blocking flow when the phloem cell is damaged. The resistance to the flow of viscous sap in the phloem vascular system is strongly affected by the presence of the sieve plates, but the hydrodynamics of the flow through them remains poorly understood. We propose a theoretical model for quantifying the effect of sieve plates on the phloem in the plant, thus unifying and improving previous work in the field. Numerical simulations of the flow in real and idealized phloem channels verify our model, and anatomical data from 19 plant species are investigated. We find that the sieve plate resistance is correlated to the cell lumen resistance, and that the sieve plate and the lumen contribute almost equally to the total hydraulic resistance of the phloem translocation pathway.

  12. In Silico Molecular Docking and In Vitro Antidiabetic Studies of Dihydropyrimido[4,5-a]acridin-2-amines

    PubMed Central

    Bharathi, A.; Roopan, Selvaraj Mohana; Vasavi, C. S.; Munusami, Punnagai; Gayathri, G. A.; Gayathri, M.

    2014-01-01

    An in vitro antidiabetic activity on α-amylase and α–glucosidase activity of novel 10-chloro-4-(2-chlorophenyl)-12-phenyl-5,6-dihydropyrimido[4,5-a]acridin-2-amines (3a–3f) were evaluated. Structures of the synthesized molecules were studied by FT-IR, 1H NMR, 13C NMR, EI-MS, and single crystal X-ray structural analysis data. An in silico molecular docking was performed on synthesized molecules (3a–3f). Overall studies indicate that compound 3e is a promising compound leading to the development of selective inhibition of α-amylase and α-glucosidase. PMID:24991576

  13. Generation of optical vortices by apodized photon sieves

    NASA Astrophysics Data System (ADS)

    Sun, Hai-bin; Wang, Xing-hai; Chen, Jun; Sun, Ping

    2016-05-01

    As a novel diffractive optical element, photon sieve has good focusing properties. We propose a method to verify the focusing properties by using apodized photon sieves. The apodized photon sieve is obtained by using a Gaussian window function to modulate the general photon sieve. Focusing properties of apodized photon sieve are studied by numerical simulations and experiments. It shows that photon sieves have good focusing ability, and the focusing ability of the photon sieve on the focal plane is stronger than that on other image planes. The experimental results also demonstrate that photon sieves can be used to generate optical vortices. The existence of optical vortices is confirmed by the formation of fork fringes. This apodized photon sieve is expected to have some practical applications in focusing analysis, optical imaging, and optical communication.

  14. SEORious business: structural proteins in sieve tubes and their involvement in sieve element occlusion.

    PubMed

    Knoblauch, Michael; Froelich, Daniel R; Pickard, William F; Peters, Winfried S

    2014-04-01

    The phloem provides a network of sieve tubes for long-distance translocation of photosynthates. For over a century, structural proteins in sieve tubes have presented a conundrum since they presumably increase the hydraulic resistance of the tubes while no potential function other than sieve tube or wound sealing in the case of injury has been suggested. Here we summarize and critically evaluate current speculations regarding the roles of these proteins. Our understanding suffers from the suggestive power of images; what looks like a sieve tube plug on micrographs may not actually impede translocation very much. Recent reports of an involvement of SEOR (sieve element occlusion-related) proteins, a class of P-proteins, in the sealing of injured sieve tubes are inconclusive; various lines of evidence suggest that, in neither intact nor injured plants, are SEORs determinative of translocation stoppage. Similarly, the popular notion that P-proteins serve in the defence against phloem sap-feeding insects is unsupported by empirical facts; it is conceivable that in functional sieve tubes, aphids actually could benefit from inducing a plug. The idea that rising cytosolic Ca(2+) generally triggers sieve tube blockage by P-proteins appears widely accepted, despite lacking experimental support. Even in forisomes, P-protein assemblages restricted to one single plant family and the only Ca(2+)-responsive P-proteins known, the available evidence does not unequivocally suggest that plug formation is the cause rather than a consequence of translocation stoppage. We conclude that the physiological roles of structural P-proteins remain elusive, and that in vivo studies of their dynamics in continuous sieve tube networks combined with flow velocity measurements will be required to (hopefully) resolve this scientific roadblock. PMID:24591057

  15. SEORious business: structural proteins in sieve tubes and their involvement in sieve element occlusion.

    PubMed

    Knoblauch, Michael; Froelich, Daniel R; Pickard, William F; Peters, Winfried S

    2014-04-01

    The phloem provides a network of sieve tubes for long-distance translocation of photosynthates. For over a century, structural proteins in sieve tubes have presented a conundrum since they presumably increase the hydraulic resistance of the tubes while no potential function other than sieve tube or wound sealing in the case of injury has been suggested. Here we summarize and critically evaluate current speculations regarding the roles of these proteins. Our understanding suffers from the suggestive power of images; what looks like a sieve tube plug on micrographs may not actually impede translocation very much. Recent reports of an involvement of SEOR (sieve element occlusion-related) proteins, a class of P-proteins, in the sealing of injured sieve tubes are inconclusive; various lines of evidence suggest that, in neither intact nor injured plants, are SEORs determinative of translocation stoppage. Similarly, the popular notion that P-proteins serve in the defence against phloem sap-feeding insects is unsupported by empirical facts; it is conceivable that in functional sieve tubes, aphids actually could benefit from inducing a plug. The idea that rising cytosolic Ca(2+) generally triggers sieve tube blockage by P-proteins appears widely accepted, despite lacking experimental support. Even in forisomes, P-protein assemblages restricted to one single plant family and the only Ca(2+)-responsive P-proteins known, the available evidence does not unequivocally suggest that plug formation is the cause rather than a consequence of translocation stoppage. We conclude that the physiological roles of structural P-proteins remain elusive, and that in vivo studies of their dynamics in continuous sieve tube networks combined with flow velocity measurements will be required to (hopefully) resolve this scientific roadblock.

  16. Recent Improvements To the Sieve of Eratosthenes.

    ERIC Educational Resources Information Center

    Quesada, Antonio R.

    1997-01-01

    Presents recently developed generalizations to the sieve of Eratosthenes, showing the principles underlying these improvements, which increase its efficiency without changing too much of its simplicity. Offers several possibilities to propose good investigations for students to explore, find patterns, and make generalizations. (JRH)

  17. Does aphid salivation affect phloem sieve element occlusion in vivo?

    PubMed Central

    Medina-Ortega, Karla J.

    2013-01-01

    To protect against loss of photo-assimilate-rich phloem sap, plants have evolved several mechanisms to plug phloem sieve tubes in response to damage. In many Fabaceae, each sieve element contains a discrete proteinaceous body called a forisome, which, in response to damage, rapidly transforms from a condensed configuration that does not impede the flow of sap to a dispersed configuration that plugs the sieve element. Aphids and other specialized phloem sap feeders can ingest phloem sap from a single sieve element for hours or days, and to do this, they must be able to suppress or reverse phloem plugging. A recent study provided in vitro evidence that aphid saliva can reverse forisome plugs. The present study tested this hypothesis in vivo by inducing forisome plugs which triggered aphids to switch behaviour from phloem sap ingestion to salivation into the sieve element. After salivating into the sieve element for various periods of time, the aphids were instantaneously cryofixed (freeze fixed) in situ on their leaf. The state of the forisome was then determined in the penetrated sieve element and in nearby non-penetrated sieve elements which served as controls for sieve elements not subjected to direct aphid salivation. Forisomes were almost always in close contact with the stylet tips and thus came into direct contact with the saliva. Nonetheless, forisome plugs in the penetrated sieve element did not revert back to a non-plugging state any faster than those in neighbouring sieve elements that were not subjected to direct aphid salivation. PMID:24127515

  18. Factorization using the quadratic sieve algorithm

    SciTech Connect

    Davis, J.A.; Holdridge, D.B.

    1983-12-01

    Since the cryptosecurity of the RSA two key cryptoalgorithm is no greater than the difficulty of factoring the modulus (product of two secret primes), a code that implements the Quadratic Sieve factorization algorithm on the CRAY I computer has been developed at the Sandia National Laboratories to determine as sharply as possible the current state-of-the-art in factoring. Because all viable attacks on RSA thus far proposed are equivalent to factorization of the modulus, sharper bounds on the computational difficulty of factoring permit improved estimates for the size of RSA parameters needed for given levels of cryptosecurity. Analysis of the Quadratic Sieve indicates that it may be faster than any previously published general purpose algorithm for factoring large integers. The high speed of the CRAY I coupled with the capability of the CRAY to pipeline certain vectorized operations make this algorithm (and code) the front runner in current factoring techniques.

  19. Factorization using the quadratic sieve algorithm

    SciTech Connect

    Davis, J.A.; Holdridge, D.B.

    1983-01-01

    Since the cryptosecurity of the RSA two key cryptoalgorithm is no greater than the difficulty of factoring the modulus (product of two secret primes), a code that implements the Quadratic Sieve factorization algorithm on the CRAY I computer has been developed at the Sandia National Laboratories to determine as sharply as possible the current state-of-the-art in factoring. Because all viable attacks on RSA thus far proposed are equivalent to factorization of the modulus, sharper bounds on the computational difficulty of factoring permit improved estimates for the size of RSA parameters needed for given levels of cryptosecurity. Analysis of the Quadratic Sieve indicates that it may be faster than any previously published general purpose algorithm for factoring large integers. The high speed of the CRAY I coupled with the capability of the CRAY to pipeline certain vectorized operations make this algorithm (and code) the front runner in current factoring techniques.

  20. Molecular basis of IgE-recognition of Lol p 5, a major allergen of rye-grass pollen.

    PubMed

    Suphioglu, C; Blaher, B; Rolland, J M; McCluskey, J; Schäppi, G; Kenrick, J; Singh, M B; Knox, R B

    1998-04-01

    Grass pollen, especially of rye-grass (Lolium perenne). represents an important cause of type I allergy. Identification of IgE-binding (allergenic) epitopes of major grass pollen allergens is essential for understanding the molecular basis of interaction between allergens and human IgE antibodies and therefore facilitates the devising of safer and more effective diagnostic and immunotherapy reagents. The aim of this study was to identify the allergenic epitopes of Lol p 5, a major allergen of rye-grass pollen, immunodissect these epitopes further so that the amino acid residues critical for antibody binding can be determined and investigate the conservation and nature of these epitopes within the context of the natural grass pollen allergens. Peptides, 12-13 amino acid residues long and overlapping each other by 4 amino acid residues, based on the entire deduced amino acid sequence of the coding region of Lol p 5, were synthesised and assayed for IgE-binding. Two strong IgE-binding epitopes (Lol p 5 (49-60) and (265-276), referred to as peptides 7 and 34, respectively) were identified. These epitopes were further resolved by truncated peptides and amino acid replacement studies and the amino acid residues critical for IgE-binding determined (Lol p 5 (49-60) residue Lys57 and (265-276) residue Lys275). Sequences of these epitopes were conserved in related allergens and may form the conserved allergenic domains responsible for the cross-reactivity observed between pollen allergens of taxonomically related grasses. Furthermore, due to its strong IgE-reactivity, synthetic peptide Lol p 5 (265-276) was used to affinity-purify specific IgE antibodies which recognised proteins of other clinically important grass pollens. further indicating presence of allergenic cross-reactivity at the level of allergenic epitope. Moreover, Lol p 5 (265 276) demonstrated a strong capacity to inhibit IgE-binding to natural rye-grass pollen proteins highlighting the antibody accessibility

  1. Sieve Tube Geometry in Relation to Phloem Flow

    PubMed Central

    Mullendore, Daniel L.; Windt, Carel W.; Van As, Henk; Knoblauch, Michael

    2010-01-01

    Sieve elements are one of the least understood cell types in plants. Translocation velocities and volume flow to supply sinks with photoassimilates greatly depend on the geometry of the microfluidic sieve tube system and especially on the anatomy of sieve plates and sieve plate pores. Several models for phloem translocation have been developed, but appropriate data on the geometry of pores, plates, sieve elements, and flow parameters are lacking. We developed a method to clear cells from cytoplasmic constituents to image cell walls by scanning electron microscopy. This method allows high-resolution measurements of sieve element and sieve plate geometries. Sieve tube–specific conductivity and its reduction by callose deposition after injury was calculated for green bean (Phaseolus vulgaris), bamboo (Phyllostachys nuda), squash (Cucurbita maxima), castor bean (Ricinus communis), and tomato (Solanum lycopersicum). Phloem sap velocity measurements by magnetic resonance imaging velocimetry indicate that higher conductivity is not accompanied by a higher velocity. Studies on the temporal development of callose show that small sieve plate pores might be occluded by callose within minutes, but plants containing sieve tubes with large pores need additional mechanisms. PMID:20354199

  2. Molecular characterization, expression, polymorphism of NR5A2 and its relationship with litter size in Hu sheep.

    PubMed

    Li, Y X; Zhang, J; Qian, Y; Meng, C H; Wang, H L; Tao, X J; Zhong, S; Cao, S X; Li, Q F

    2015-01-01

    NR5A2 has been implicated in processes as diverse as steroidogenesis, cellular proliferation, ovarian follicular development, ovulation, and fertility in mammals. However, data about the relationship between NR5A2 and prolificacy in mammals are lacking. In the present study, we identified and characterized NR5A2 of Hu sheep, and investigated the correlation between NR5A2 and reproductive performance. The full-length coding region was 1488 bp, and the gene was conserved in mammals. We found a positive correlation between NR5A2 mRNA levels in the ovary and the ovulation rate and litter size of Hu sheep. We detected two single nucleotide polymorphisms (T40C and T1419C) in the coding sequence of NR5A2. At the third and average parity, litter size of Hu ewes with CC genotype at T40C locus was larger than those of ewes with TT or TC genotypes; at the T1419C locus, Hu ewes with TT genotype was greater than those of ewes with CC genotype at the third parity. Our findings demonstrated that NR5A2 was associated with reproductive performance in Hu sheep, a high prolificacy breed. PMID:26505427

  3. The Autophagic Process Occurs in Human Bone Metastasis and Implicates Molecular Mechanisms Differently Affected by Rab5a in the Early and Late Stages

    PubMed Central

    Maroni, Paola; Bendinelli, Paola; Resnati, Massimo; Matteucci, Emanuela; Milan, Enrico; Desiderio, Maria Alfonsina

    2016-01-01

    Autophagy favours metastatic growth through fuelling energy and nutrients and resistance to anoikis, typical of disseminated-tumour cells. The autophagic process, mediated by a unique organelle, the autophagosome, which fuses with lysosomes, is divided into three steps. Several stages, especially early omegasome formation and isolation-membrane initiation, remain controversial; molecular mechanisms involve the small-GTPase Rab5a, which regulates vesicle traffic for autophagosome formation. We examined Rab5a involvement in the function of key members of ubiquitin-conjugation systems, Atg7 and LC3-lipidated, interacting with the scaffold-protein p62. Immunohistochemistry of Rab5a was performed in human specimens of bone metastasis and pair-matched breast carcinoma; the autophagic-molecular mechanisms affected by Rab5a were evaluated in human 1833 bone metastatic cells, derived from breast-carcinoma MDA-MB231 cells. To clarify the role of Rab5a, 1833 cells were transfected transiently with Rab5a-dominant negative, and/or stably with the short-hairpin RNA Atg7, were exposed to two inhibitors of autolysosome function, and LC3II and p62 expression was measured. We showed basal autophagy in bone-metastatic cells and the pivotal role of Rab5a together with Beclin 1 between the early stages, elongation of isolation membrane/closed autophagosome mediated by Atg7, and the late-degradative stages. This regulatory network might occur in bone-metastasis and in high-grade dysplastic lesions, preceding invasive-breast carcinoma and conferring phenotypic characteristics for dissemination. PMID:27023526

  4. Resolution enhancement of photon sieve based on apodization

    NASA Astrophysics Data System (ADS)

    Cheng, Guanxiao; Xing, Tingwen; Liao, Zhijie; Yang, Yong; Ma, Jianling

    2008-03-01

    Photon sieve is a novel diffractive optical element modulating either amplitude or phase which consists of a great number of pinholes distributed appropriately over the Fresnel zones for the focusing and imaging of light. Photon sieve has the advantages of the diameter of pinholes beyond the limitation of the corresponding Fresnel zone width and the minimum background in the focal plane. Furthermore, photon sieve can be fabricated on a single surface without any supporting struts required unlike the Fresnel zone plate. Photon sieve can be used as EUV telescope for solar orbiter, space-based surveillance telescope operating at visible light, or other imaging components. Photon sieve can also be used as one of the promising lithographic tools for nanoscale science and engineering to obtain the lower cost, higher flexibility and better resolution. The approaches to enhancing imaging resolution of photon sieve are presented in detail. According to Fresnel-Kirchhoff diffraction theory, the diffractive field of photon sieve is described by means of the discrete fast Fourier transform algorithm. The related contents include the calculation of point spread function, the suppression of side lobes, the imaging bandwidth, the physical limit of resolution, and the diffraction efficiency. Imaging properties of photon sieve are analyzed on the basis of precise test.

  5. Isolation and molecular characterization of Shewanella sp. G5, a producer of cold-active beta-D-glucosidases.

    PubMed

    Cristóbal, Héctor Antonio; Breccia, Javier Darío; Abate, Carlos Mauricio

    2008-02-01

    beta -Glucosidase is a highly desired glycosidase, especially for hydrolysis of glycoconjugated precursors in musts and wines for the release of active aromatic compounds. A Shewanella sp. G5 strain was isolated from the intestinal content of benthonic organism (Munida subrrugosa) from different coastal areas of the Beagle Channel, Tierra del Fuego (Argentina). This marine bacterium was able to grow at a temperature range between 4 to 20 degrees C using different beta-glycoside substrates, such as cellobiose, as carbon source. In this work, the Shewanella sp. G5 strain exhibited high beta-glucosidase activity on plate at low temperature (4 and 20 degrees C). Two genes encoding different cold-active beta-glucosidases were amplified and sequenced and the nucleotide sequences were submitted to the GenBank. 16S rDNA and gyrB gene sequences were used for the molecular characterization of Shewanella sp. G5. PMID:18247390

  6. Subnanometer Two-Dimensional Graphene Oxide Channels for Ultrafast Gas Sieving.

    PubMed

    Shen, Jie; Liu, Gongping; Huang, Kang; Chu, Zhenyu; Jin, Wanqin; Xu, Nanping

    2016-03-22

    Two-dimensional (2D) materials with atomic thickness and extraordinary physicochemical properties exhibit unique mass transport behaviors, enabling them as emerging nanobuilding blocks for separation membranes. Engineering 2D materials into membrane with subnanometer apertures for precise molecular sieving remains a great challenge. Here, we report rational-designing external forces to precisely manipulate nanoarchitecture of graphene oxide (GO)-assembled 2D channels with interlayer height of ∼0.4 nm for fast transporting and selective sieving gases. The external forces are synergistic to direct the GO nanosheets stacking so as to realize delicate size-tailoring of in-plane slit-like pores and plane-to-plane interlayer-galleries. The 2D channels endow GO membrane with excellent molecular-sieving characteristics that offer 2-3 orders of magnitude higher H2 permeability and 3-fold enhancement in H2/CO2 selectivity compared with commercial membranes. Formation mechanism of 2D channels is proposed on the basis of the driving forces, nanostructures, and transport behaviors.

  7. Dense molecular cocoons in the massive protocluster W3 IRS5: a test case for models of massive star formation

    NASA Astrophysics Data System (ADS)

    Wang, K.-S.; Bourke, T. L.; Hogerheijde, M. R.; van der Tak, F. F. S.; Benz, A. O.; Megeath, S. T.; Wilson, T. L.

    2013-10-01

    Context. Two competing models describe the formation of massive stars in objects like the Orion Trapezium. In the turbulent core accretion model, the resulting stellar masses are directly related to the mass distribution of the cloud condensations. In the competitive accretion model, the gravitational potential of the protocluster captures gas from the surrounding cloud for which the individual cluster members compete. Aims: With high resolution submillimeter observations of the structure, kinematics, and chemistry of the proto-Trapezium cluster W3 IRS5, we aim to determine which mode of star formation dominates. Methods: We present 354 GHz Submillimeter Array observations at resolutions of 1″-3″ (1800-5400 AU) of W3 IRS5. The dust continuum traces the compact source structure and masses of the individual cores, while molecular lines of CS, SO, SO2, HCN, H2CS, HNCO, and CH3OH (and isotopologues) reveal the gas kinematics, density, and temperature. Results: The observations show five emission peaks (SMM1-5). SMM1 and SMM2 contain massive embedded stars (~20 M⊙); SMM3-5 are starless or contain low-mass stars (<8 M⊙). The inferred densities are high, ≥107 cm-3, but the core masses are small, 0.2-0.6 M⊙. The detected molecular emission reveals four different chemical zones. Abundant (X ~ few 10-7 to 10-6) SO and SO2 are associated with SMM1 and SMM2, indicating active sulfur chemistry. A low abundance (5 × 10-8) of CH3OH concentrated on SMM3/4 suggest the presence of a hot core that is only just turning on, possibly by external feedback from SMM1/2. The gas kinematics are complex with contributions from a near pole-on outflow traced by CS, SO, and HCN; rotation in SO2, and a jet in vibrationally excited HCN. Conclusions: The proto-Trapezium cluster W3 IRS5 is an ideal test case to discriminate between models of massive star formation. Either the massive stars accrete locally from their local cores; in this case the small core masses imply that W3 IRS5 is

  8. Continuous-Flow Bioseparation Using Microfabricated Anisotropic Nanofluidic Sieving Structures

    PubMed Central

    Fu, Jianping; Mao, Pan; Han, Jongyoon

    2010-01-01

    The anisotropic nanofluidic filter (nanofilter) array (ANA) is a unique molecular sieving structure for separating biomolecules. Here we describe fabrication of planar and vertical ANA chips and how to perform continuous-flow bioseparation using them. This protocol is most useful for bioengineers that are interested in developing automated multistep chip-based bioanalysis systems and assumes prior cleanroom microfabrication knowledge. The ANA consists of a two-dimensional periodic nanofilter array, and the designed structural anisotropy of the ANA causes different sized- or charged-biomolecules to follow distinct trajectories under applied electric fields, leading to efficient continuous-flow separation. Using microfluidic channels surrounding the ANA, the fractionated biomolecule streams are collected and routed to different fluid channels or reservoirs for convenient sample recovery and downstream bioanalysis. The ANA is physically robust and can be reused repeatedly. Compared to conventional gel-based separation techniques, the ANA offers the potential for faster separation, higher throughput, and more convenient sample recovery. PMID:19876028

  9. Threshold microsclerotial inoculum for cotton verticillium wilt determined through wet-sieving and real-time quantitative PCR.

    PubMed

    Wei, Feng; Fan, Rong; Dong, Haitao; Shang, Wenjing; Xu, Xiangming; Zhu, Heqin; Yang, Jiarong; Hu, Xiaoping

    2015-02-01

    Quantification of Verticillium dahliae microsclerotia is an important component of wilt management on a range of crops. Estimation of microsclerotia by dry or wet sieving and plating of soil samples on semiselective medium is a commonly used technique but this method is resource-intensive. We developed a new molecular quantification method based on Synergy Brands (SYBR) Green real-time quantitative polymerase chain reaction of wet-sieving samples (wet-sieving qPCR). This method can detect V. dahliae microsclerotia as low as 0.5 CFU g(-1) of soil. There was a high correlation (r=0.98) between the estimates of conventional plating analysis and the new wet-sieving qPCR method for 40 soil samples. To estimate the inoculum threshold for cotton wilt, >400 soil samples were taken from the rhizosphere of individual plants with or without visual wilt symptoms in experimental and commercial cotton fields at the boll-forming stage. Wilt inoculum was estimated using the wet-sieving qPCR method and related to wilt development. The estimated inoculum threshold varied with cultivar, ranging from 4.0 and 7.0 CFU g(-1) of soil for susceptible and resistant cultivars, respectively. In addition, there was an overall relationship of wilt incidence with inoculum density across 31 commercial fields where a single composite soil sample was taken at each field, with an estimated inoculum threshold of 11 CFU g(-1) of soil. These results suggest that wilt risk can be predicted from the estimated soil inoculum density using the new wet-sieving qPCR method. We recommend the use of 4.0 and 7.0 CFU g(-1) as an inoculum threshold on susceptible and resistant cultivars, respectively, in practical risk prediction schemes.

  10. 7 CFR 801.8 - Tolerances for sieves.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... Regulations of the Department of Agriculture (Continued) GRAIN INSPECTION, PACKERS AND STOCKYARD ADMINISTRATION (FEDERAL GRAIN INSPECTION SERVICE), DEPARTMENT OF AGRICULTURE OFFICIAL PERFORMANCE REQUIREMENTS FOR GRAIN INSPECTION EQUIPMENT § 801.8 Tolerances for sieves. The maintenance tolerances for...

  11. 7 CFR 801.8 - Tolerances for sieves.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... Regulations of the Department of Agriculture (Continued) GRAIN INSPECTION, PACKERS AND STOCKYARD ADMINISTRATION (FEDERAL GRAIN INSPECTION SERVICE), DEPARTMENT OF AGRICULTURE OFFICIAL PERFORMANCE REQUIREMENTS FOR GRAIN INSPECTION EQUIPMENT § 801.8 Tolerances for sieves. The maintenance tolerances for...

  12. 7 CFR 801.8 - Tolerances for sieves.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... Regulations of the Department of Agriculture (Continued) GRAIN INSPECTION, PACKERS AND STOCKYARD ADMINISTRATION (FEDERAL GRAIN INSPECTION SERVICE), DEPARTMENT OF AGRICULTURE OFFICIAL PERFORMANCE REQUIREMENTS FOR GRAIN INSPECTION EQUIPMENT § 801.8 Tolerances for sieves. The maintenance tolerances for...

  13. 7 CFR 801.8 - Tolerances for sieves.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... Regulations of the Department of Agriculture (Continued) GRAIN INSPECTION, PACKERS AND STOCKYARD ADMINISTRATION (FEDERAL GRAIN INSPECTION SERVICE), DEPARTMENT OF AGRICULTURE OFFICIAL PERFORMANCE REQUIREMENTS FOR GRAIN INSPECTION EQUIPMENT § 801.8 Tolerances for sieves. The maintenance tolerances for...

  14. 7 CFR 801.8 - Tolerances for sieves.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... Regulations of the Department of Agriculture (Continued) GRAIN INSPECTION, PACKERS AND STOCKYARD ADMINISTRATION (FEDERAL GRAIN INSPECTION SERVICE), DEPARTMENT OF AGRICULTURE OFFICIAL PERFORMANCE REQUIREMENTS FOR GRAIN INSPECTION EQUIPMENT § 801.8 Tolerances for sieves. The maintenance tolerances for...

  15. Post-sieve element transport of photoassimilates in sink regions.

    PubMed

    Patrick, J W; Offler, C E

    1996-08-01

    Photoassimilate transport from the sieve elements to the recipient sink cells, principally in the form of sucrose, provides a link between sink metabolism and compartmentation with phloem import. Phloem unloading has focused attention on photoassimilate transport across the sieve element boundary. However, post-sieve element transport can be of equal or greater significance. Three cellular pathways of sieve element unloading and post-sieve element transport are identified. These are apoplastic, symplastic and symplastic interrupted by an apoplastic step. The symplastic path is considered to be the common path, while the remaining pathways serve specialized functions. In particular, the apoplastic step isolates the sieve element transport function from the effects of solute concentration or osmotic changes in the sink cells. Switching between apo- and symplastic routes within a given sink has been found to be linked with such changes. Plasmodesmatal transport undoubtedly involves a diffusive component, but whether bulk flow contributes to the symplastic flux of photoassimilate from the sieve elements to the recipient sink cells is yet to be established unequivocally. Efflux across the plasma membranes of the sieve element-companion cell (se-cc) complexes and other vascular cells occurs by passive diffusion. Along the axial route, retrieval from the phloem apoplast is mediated by sucrose/proton symport. However, this mechanism is absent in terminal sinks. Non-vascular efflux from the maternal tissues of developing seed is passive in cereals and energy-coupled in certain grain legumes. Accumulation of sugars from the apoplast of all sinks with an apoplastic step universally occurs by a plasma membrane-bound sugar/proton symport mechanism. Regulation of symplastic transport could be mediated by a combination of sink metabolism and compartmentation coupled with changes in the transport properties of the interconnecting plasmodesmata. PMID:21245245

  16. Carbon-fiber composite molecular sieves for gas separation

    SciTech Connect

    Jagtoyen, M.; Derbyshire, F.; Kimber, G.; Fei, Y.Q.

    1995-08-01

    The progress of research in the development of novel, rigid, monolithic adsorbent carbon fiber composites is described. Carbon fiber composites are produced at ORNL and activated at the CAER using steam or CO{sub 2} under different conditions, with the aims of producing a uniform degree of activation through the material, and of closely controlling pore structure and adsorptive properties The principal focus of the work to date has been to produce materials with narrow porosity for use in gas separations.

  17. Preparation of Fe/Mo/molecular sieves by CVD

    SciTech Connect

    Yoo, Jin S.; Donohu, J.A.; Choi-Feng, C.

    1995-12-01

    A series of mixed metal oxide catalysts was prepared via the chemical vapor deposition (CVD) technique by using the silanol moiety existing on various zeolite matrices as an anchoring site for metals. The novel CVD Fe/Mo/DBH catalyst was made by depositing FeCl{sub 3} and then MoO{sub 2}Cl{sub 2} on the partially deboronated borosilicate (DBH). The catalyst precursor was activated by calcining it at 650-690{degrees}C for prolonged period. Among the zeolite matrices such as borosilicate, silicalite, ZSM-5, {beta}-zeolite and {Upsilon}-zeolite, the DBH exhibited a unique papra-selective oxidation property for the gas-phase O{sub 2} oxidation of polymethylated benzenes. Terephthaldehyde was produced in the oxidation of p-xylene. The impregnated catalyst was also prepared by the incipient wetness method. The catalyst performance and the stability of the impregnated catalyst were compared with those of the CVD counterpart. The CVD catalyst was more active and showed better stability than the impregnated catalyst. These catalysts were characterized by ammonia TPD, Raman spectroscopy, and electron microscopy with an objective of explaining these findings.

  18. Advanced Nanostructured Molecular Sieves for Energy Efficient Industrial Separations

    SciTech Connect

    Kunhao Li, Michael Beaver

    2012-01-18

    Due to the very small relative volatility difference between propane and propylene, current propane/propylene separation by distillation requires very tall distillation towers (150-250 theoretical plates) and large reflux ratios (up to 15), which is considered to be the most energy consuming large-scale separation process. Adsorptive separation processes are widely considered to be more energy-efficient alternatives to distillation. However, slow diffusion kinetics/mass transport rate through the adsorbent bed often limits the performance of such processes, so further improvements are possible if intra-particle mass transfer rates can be improved. Rive Technology, Inc. is developing and commercializing its proprietary mesoporous zeolite technology for catalysis and separation. With well-controlled intracrystalline mesoporosity, diffusion kinetics through such mesoporous zeolite based catalysts is much improved relative to conventional zeolites, leading to significantly better product selectivity. This 'proof-of-principle' project (DE-EE0003470) is intended to demonstrate that Rive mesoporous zeolite technology can be extended and applied in adsorptive propane/propylene separation and lead to significant energy saving compared to the current distillation process. In this project, the mesoporous zeolite Y synthesis technology was successfully extended to X and A zeolites that are more relevant to adsorbent applications. Mesoporosity was introduced to zeolite X and A for the first time while maintaining adequate adsorption capacity. Zeolite adsorbents were tested for liquid phase separation performance using a pulse flow test unit and the test results show that the separation selectivity of the mesoporous zeolite adsorbent is much closer to optimal for a Simulated Moving Bed (SMB) separation process and the enhanced mesoporosity lead to >100% increase of overall mass transport rate for propane and propylene. These improvements will significantly improve the performance of an adsorptive separation unit for propane/propylene separation compared with traditional zeolite adsorbents. The enhanced transport will allow for more efficient utilization of a given adsorbent inventory by reducing process cycle time, allowing a faster production rate with a fixed amount of adsorbent or smaller adsorbent inventory at a fixed production rate. Smaller adsorbent inventory would also lead to significant savings in the capital cost due to smaller footprint of the equipment. Energy consumption calculation, based on the pulse test results for rived NaX zeolite adsorbent, of a hypothetical moderate-scale SMB propane/propylene separation plant that processes 6000 BPSD refinery grade propylene (70% propylene) will consume about 60-80% less energy (both re-boiler and condenser duties) compared to a C3 splitter that process the same amount of feed. This energy saving also translates to a reduction of 30,000-35,000 tons of CO2 emission per year at this moderate processing rate. The enhancement of mass transport achievable by introduction of controlled mesoporosity to the zeolite also opens the door for the technology to be applied to several other adsorption separation processes such as the separation of xylene isomers by SMB, small- and large scale production of O2/N2 from air by pressure swing adsorption, the separation of CO2 from natural gas at natural gas wellheads, and the purification of ultra-high purity H2 from the off gas produced by steam-methane-reforming.

  19. Carbon-fiber composite molecular sieves for gas separation

    SciTech Connect

    Jagtoyen, M.; Derbyshire, F.

    1996-08-01

    This report describes continuing work on the activation and characterization of formed carbon fiber composites. The composites are produced at the Oak Ridge National Laboratory (ORNL) and activated at the Center for Applied Energy Research (CAER) using steam, CO{sub 2}, or O{sub 2} at different conditions of temperature and time, and with different furnace configurations. The general aims of the project are to produce uniformly activated samples with controlled pore structures for specialist applications such as gas separation and water treatment. In previous work the authors reported that composites produced from isotropic pitch fibers weighing up to 25g can be uniformly activated through the appropriate choice of reaction conditions and furnace configurations. They have now succeeded in uniformly activating composites of dimensions up to 12 x 7 x 6 cm, or up to about 166 gram - a scale-up factor of about six. Part of the work has involved the installation of a new furnace that can accommodate larger composites. Efforts were made to achieve uniform activation in both steam and CO{sub 2}. The authors have also succeeded in producing materials with very uniform and narrow pore size distributions by using a novel method involving low temperature oxygen chemisorption in combination with heat treatment in N{sub 2} at high temperatures. Work has also started on the activation of PAN based carbon fibers and fiber composites with the aim of producing composites with wide pore structures for use as catalyst supports. So far activation of the PAN fiber composites supplied by ORNL has been difficult which is attributed to the low reactivity of the PAN fibers. As a result, studies are now being made of the activation of the PAN fibers to investigate the optimum carbonization and activation conditions for PAN based fibers.

  20. Molecular sieve sensors for selective detection at the nanogram level

    DOEpatents

    Bein, Thomas; Brown, Kelly D.; Frye, Gregory C.; Brinker, Charles J.

    1992-01-01

    The invention relates to a selective chemical sensor for selective detection of chemical entities even at the nanogram level. The invention further relates to methods of using the sensor. The sensor comprises: (a) a piezoelectric substrate capable of detecting mass changes resulting from adsorption of material thereon; and (b) a coating applied to the substrate, which selectively sorbs chemical entities of a size smaller than a preselected magnitude.

  1. Titania nanoparticles synthesis in mesoporous molecular sieve MCM-41.

    PubMed

    Lihitkar, N B; Abyaneh, Majid Kazemian; Samuel, V; Pasricha, R; Gosavi, S W; Kulkarni, S K

    2007-10-01

    Nanocrystalline titanium oxide (TiO(2)) is one of the most useful oxide material, because of its widespread applications in photocatalysis, solar energy conversion, sensors and optoelectronics. The control of particle size and monodispersity of TiO(2) nanoparticles is a challenging task. The use of MCM-41, an inorganic template of uniform pore size (2-10 nm), can overcome this difficulty and produce stable nanoparticles of uniform size and shape. Here, we demonstrate the synthesis of titania nanoparticles inside the pores of silica based MCM-41 forming a TiO(2)/Si-MCM composite. Composites are formed in the alcoholic medium by incipient wetness impregnation method. Titania particles of average 3 nm size are obtained. Effect of silica and titania precursors on the quality of nanoparticles has been investigated. The characterization of titania-MCM-41 composites has been carried out using a variety of techniques like UV-vis absorption spectroscopy, X-ray diffraction, FT-IR spectroscopy, X-ray photoelectron spectroscopy, transmission electron microscopy and photoluminescence spectroscopy. It has been found that the titania particles are co-ordinated with Si-MCM by SiOTi covalent bond. PMID:17586518

  2. Effects of Mesh Size on Sieved Samples of Corophium volutator

    NASA Astrophysics Data System (ADS)

    Crewe, Tara L.; Hamilton, Diana J.; Diamond, Antony W.

    2001-08-01

    Corophium volutator (Pallas), gammaridean amphipods found on intertidal mudflats, are frequently collected in mud samples sieved on mesh screens. However, mesh sizes used vary greatly among studies, raising the possibility that sampling methods bias results. The effect of using different mesh sizes on the resulting size-frequency distributions of Corophium was tested by collecting Corophium from mud samples with 0·5 and 0·25 mm sieves. More than 90% of Corophium less than 2 mm long passed through the larger sieve. A significantly smaller, but still substantial, proportion of 2-2·9 mm Corophium (30%) was also lost. Larger size classes were unaffected by mesh size. Mesh size significantly changed the observed size-frequency distribution of Corophium, and effects varied with sampling date. It is concluded that a 0·5 mm sieve is suitable for studies concentrating on adults, but to accurately estimate Corophium density and size-frequency distributions, a 0·25 mm sieve must be used.

  3. Mesh Algorithms for PDE with Sieve I: Mesh Distribution

    DOE PAGESBeta

    Knepley, Matthew G.; Karpeev, Dmitry A.

    2009-01-01

    We have developed a new programming framework, called Sieve, to support parallel numerical partial differential equation(s) (PDE) algorithms operating over distributed meshes. We have also developed a reference implementation of Sieve in C++ as a library of generic algorithms operating on distributed containers conforming to the Sieve interface. Sieve makes instances of the incidence relation, or arrows, the conceptual first-class objects represented in the containers. Further, generic algorithms acting on this arrow container are systematically used to provide natural geometric operations on the topology and also, through duality, on the data. Finally, coverings and duality are used to encode notmore » only individual meshes, but all types of hierarchies underlying PDE data structures, including multigrid and mesh partitions. In order to demonstrate the usefulness of the framework, we show how the mesh partition data can be represented and manipulated using the same fundamental mechanisms used to represent meshes. We present the complete description of an algorithm to encode a mesh partition and then distribute a mesh, which is independent of the mesh dimension, element shape, or embedding. Moreover, data associated with the mesh can be similarly distributed with exactly the same algorithm. The use of a high level of abstraction within the Sieve leads to several benefits in terms of code reuse, simplicity, and extensibility. We discuss these benefits and compare our approach to other existing mesh libraries.« less

  4. Microfabricated Sieve for the Continuous Sorting of Macromolecules

    NASA Astrophysics Data System (ADS)

    Duke, T. A. J.; Austin, R. H.

    1998-02-01

    In a two-dimensional periodic but asymmetric environment, a Brownian particle that is driven in one direction by a potential gradient will also drift in the orthogonal direction at a rate that depends on its diffusion coefficient. On this basis, we propose a new method for separating biological macromolecules according to size. A fine stream of molecules is electrophoresed through a microfabricated sieve, etched from a silicon chip by lithography. The sieve consists of a periodic array of oblong obstacles, which deflect the molecules so that each species follows a different trajectory, oblique to the flow. Advantages promised by the technique include improved efficiency, continuous sorting and ready automation.

  5. Molecular separation method and apparatus

    DOEpatents

    Villa-Aleman, E.

    1996-04-09

    A method and apparatus are disclosed for separating a gaseous mixture of chemically identical but physically different molecules based on their polarities. The gaseous mixture of molecules is introduced in discrete quantities into the proximal end of a porous glass molecular sieve. The molecular sieve is exposed to microwaves to excite the molecules to a higher energy state from a lower energy state, those having a higher dipole moment being excited more than those with a lower energy state. The temperature of the sieve kept cold by a flow of liquid nitrogen through a cooling jacket so that the heat generated by the molecules colliding with the material is transferred away from the material. The molecules thus alternate between a higher energy state and a lower one, with the portion of molecules having the higher dipole moment favored over the others. The former portion can then be extracted separately from the distal end of the molecular sieve. 2 figs.

  6. Ultra-broadband achromatic imaging with diffractive photon sieves

    PubMed Central

    Zhao, Xiaonan; Hu, Jingpei; Lin, Yu; Xu, Feng; Zhu, Xiaojun; Pu, Donglin; Chen, Linsen; Wang, Chinhua

    2016-01-01

    Diffractive optical elements suffer from large chromatic aberration due to the strong wavelength-dependent nature in diffraction phenomena, and therefore, diffractive elements can work only at a single designed wavelength, which significantly limits the applications of diffractive elements in imaging. Here, we report on a demonstration of a wavefront coded broadband achromatic imaging with diffractive photon sieves. The broadband diffraction imaging is implemented with a wavefront coded pinhole pattern that generates equal focusing power for a wide range of operating wavelength in a single thin-film element without complicated auxiliary optical system. Experimental validation was performed using an UV-lithography fabricated wavefront coded photon sieves. Results show that the working bandwidth of the wavefront coded photon sieves reaches 28 nm compared with 0.32 nm of the conventional one. Further demonstration of the achromatic imaging with a bandwidth of 300 nm is also performed with a wavefront coded photon sieves integrated with a refractive element. PMID:27328713

  7. Ultra-broadband achromatic imaging with diffractive photon sieves

    NASA Astrophysics Data System (ADS)

    Zhao, Xiaonan; Hu, Jingpei; Lin, Yu; Xu, Feng; Zhu, Xiaojun; Pu, Donglin; Chen, Linsen; Wang, Chinhua

    2016-06-01

    Diffractive optical elements suffer from large chromatic aberration due to the strong wavelength-dependent nature in diffraction phenomena, and therefore, diffractive elements can work only at a single designed wavelength, which significantly limits the applications of diffractive elements in imaging. Here, we report on a demonstration of a wavefront coded broadband achromatic imaging with diffractive photon sieves. The broadband diffraction imaging is implemented with a wavefront coded pinhole pattern that generates equal focusing power for a wide range of operating wavelength in a single thin-film element without complicated auxiliary optical system. Experimental validation was performed using an UV-lithography fabricated wavefront coded photon sieves. Results show that the working bandwidth of the wavefront coded photon sieves reaches 28 nm compared with 0.32 nm of the conventional one. Further demonstration of the achromatic imaging with a bandwidth of 300 nm is also performed with a wavefront coded photon sieves integrated with a refractive element.

  8. Flow Characteristics of Human Erythrocytes through Polycarbonate Sieves.

    PubMed

    Gregersen, M I; Bryant, C A; Hammerle, W E; Usami, S; Chien, S

    1967-08-18

    We used polycarbonate sieves with uniform cylindrical pores (2.4 to 6.8 microns in diameter) to filter suspensions of human erythrocytes (mean major diameter is 7.2 microns) in Eagle-albumin solution. With 6.8-micron sieves the pressure-flow curves are convexed to the pressure-axis at low pressures and become linear with high pressures. With 4.5-micron sieves, however, the pressure-flow relationship is linear throughout the range of study. In both types of sieves, flow rate is reduced progressively with increasing concentration of red blood cells (RBC) over a range of 0.5 to 95 percent. The resistance to flow of RBC suspensions is higher in 4.5-micron than in 6.8-micron pores. With filter pore diameters of 3.0 microns or more, the RBC concentration in the filtrate was 100 percent of that in the solution being filtered, but only 70 percent with 2.4-micron pores. The observed critical pore diameter for 100 percent cell transmission agrees with theoretical calculation based on the assumption that the RBC membrane is deformable but nonextensible. The importance of cell deformation in the passage of RBC's through small pores is shown by the inability of RBC hardened in acetaldehyde to pass pores with 6.8-micron diameter.

  9. Focusing properties of phase-only generalized Fibonacci photon sieves

    NASA Astrophysics Data System (ADS)

    Ke, Jie; Zhang, Junyong

    2016-06-01

    We propose a new algorithm to extend the standard Fibonacci photon sieve to the phase-only generalized Fibonacci photon sieve (GFiPS) and find that the focusing properties of the phase-only GFiPS are only relevant to the characteristic roots of the recursion relation of the generalized Fibonacci sequences. By switching the transparent and opaque zones on the basis of the generalized Fibonacci sequences, we not only realize adjustable bifocal lengths, but also give their corresponding analytic expressions. Besides, we investigate a special phase-only GFiPS, a spiral-phase GFiPS, which can present twin vortices along the axial coordinate. Compared with the single focusing system, bifocal system can be exploited to enhance the processing speed, and offer a broad range of applications, such as direct laser writing, optical tweezers or atom trapping and paralleled fluorescence microscope.

  10. Size-reduction and sorting behavior in sieve hammer mills

    NASA Astrophysics Data System (ADS)

    Schallnus, Harald

    Experiments were performed in a continuously operating sieve hammer mill to determine the duration of presence of the material to be ground in the size reduction machine. The test stand, analysis techniques, evaluation methods, and selection and production of samples are described. It is shown that the duration of presence of the material in the grinding space of the mill is approximately comparable to that in an ideal mixer. The type of sieve casing has an essential effect on the duration of presence. A combined model for the description of the size reduction and sorting behavior which allows the determination of the process coefficients (size reduction speed, sorting speed, mass transition coefficient) and their dependence on the different parameters, was developed.

  11. A differential delay equation arising from the sieve of Eratosthenes

    NASA Technical Reports Server (NTRS)

    Cheer, A. Y.; Goldston, D. A.

    1990-01-01

    Consideration is given to the differential delay equation introduced by Buchstab (1937) in connection with an asymptotic formula for the uncanceled terms in the sieve of Eratosthenes. Maier (1985) used this result to show there is unexpected irreqularity in the distribution of primes in short intervals. The function omega(u) is studied in this paper using numerical and analytical techniques. The results are applied to give some numerical constants in Maier's theorem.

  12. 3D Oxidized Graphene Frameworks for Efficient Nano Sieving.

    PubMed

    Pawar, Pranav Bhagwan; Saxena, Sumit; Badhe, Dhanashree Kamlesh; Chaudhary, Raghvendra Pratap; Shukla, Shobha

    2016-02-19

    The small size of Na(+) and Cl(-) ions provides a bottleneck in desalination and is a challenge in providing alternatives for continuously depleting fresh water resources. Graphene by virtue of its structural properties has the potential to address this issue. Studies have indicated that use of monolayer graphene can be used to filter micro volumes of saline solution. Unfortunately it is extremely difficult, resource intensive and almost impractical with current technology to fabricate operational devices using mono-layered graphene. Nevertheless, graphene based devices still hold the key to solve this problem due to its nano-sieving ability. Here we report synthesis of oxidized graphene frameworks and demonstrate a functional device to desalinate and purify seawater from contaminants including Na(+) and Cl(-) ions, dyes and other microbial pollutants. Micro-channels in these frameworks help in immobilizing larger suspended solids including bacteria, while nano-sieving through graphene enables the removal of dissolved ions (e.g. Cl(-)). Nano-sieving incorporated with larger frameworks has been used in filtering Na(+) and Cl(-) ions in functional devices.

  13. Predictability sieve, pointer states, and the classicality of quantum trajectories

    SciTech Connect

    Dalvit, D. A. R.; Zurek, W. H.; Dziarmaga, J.

    2005-12-15

    We study various measures of classicality of the states of open quantum systems subject to decoherence. Classical states are expected to be stable in spite of decoherence, and are thought to leave conspicuous imprints on the environment. Here these expected features of environment-induced superselection are quantified using four different criteria: predictability sieve (which selects states that produce least entropy), purification time (which looks for states that are the easiest to find out from the imprint they leave on the environment), efficiency threshold (which finds states that can be deduced from measurements on a smallest fraction of the environment), and purity loss time (that looks for states for which it takes the longest to lose a set fraction of their initial purity). We show that when pointer states--the most predictable states of an open quantum system selected by the predictability sieve--are well defined, all four criteria agree that they are indeed the most classical states. We illustrate this with two examples: an underdamped harmonic oscillator, for which coherent states are unanimously chosen by all criteria, and a free particle undergoing quantum Brownian motion, for which most criteria select almost identical Gaussian states (although, in this case, the predictability sieve does not select well defined pointer states)

  14. 3D Oxidized Graphene Frameworks for Efficient Nano Sieving.

    PubMed

    Pawar, Pranav Bhagwan; Saxena, Sumit; Badhe, Dhanashree Kamlesh; Chaudhary, Raghvendra Pratap; Shukla, Shobha

    2016-01-01

    The small size of Na(+) and Cl(-) ions provides a bottleneck in desalination and is a challenge in providing alternatives for continuously depleting fresh water resources. Graphene by virtue of its structural properties has the potential to address this issue. Studies have indicated that use of monolayer graphene can be used to filter micro volumes of saline solution. Unfortunately it is extremely difficult, resource intensive and almost impractical with current technology to fabricate operational devices using mono-layered graphene. Nevertheless, graphene based devices still hold the key to solve this problem due to its nano-sieving ability. Here we report synthesis of oxidized graphene frameworks and demonstrate a functional device to desalinate and purify seawater from contaminants including Na(+) and Cl(-) ions, dyes and other microbial pollutants. Micro-channels in these frameworks help in immobilizing larger suspended solids including bacteria, while nano-sieving through graphene enables the removal of dissolved ions (e.g. Cl(-)). Nano-sieving incorporated with larger frameworks has been used in filtering Na(+) and Cl(-) ions in functional devices. PMID:26892277

  15. 3D Oxidized Graphene Frameworks for Efficient Nano Sieving

    PubMed Central

    Pawar, Pranav Bhagwan; Saxena, Sumit; Badhe, Dhanashree Kamlesh; Chaudhary, Raghvendra Pratap; Shukla, Shobha

    2016-01-01

    The small size of Na+ and Cl− ions provides a bottleneck in desalination and is a challenge in providing alternatives for continuously depleting fresh water resources. Graphene by virtue of its structural properties has the potential to address this issue. Studies have indicated that use of monolayer graphene can be used to filter micro volumes of saline solution. Unfortunately it is extremely difficult, resource intensive and almost impractical with current technology to fabricate operational devices using mono-layered graphene. Nevertheless, graphene based devices still hold the key to solve this problem due to its nano-sieving ability. Here we report synthesis of oxidized graphene frameworks and demonstrate a functional device to desalinate and purify seawater from contaminants including Na+ and Cl− ions, dyes and other microbial pollutants. Micro-channels in these frameworks help in immobilizing larger suspended solids including bacteria, while nano-sieving through graphene enables the removal of dissolved ions (e.g. Cl−). Nano-sieving incorporated with larger frameworks has been used in filtering Na+ and Cl− ions in functional devices. PMID:26892277

  16. (Questions)n on phloem biology. 2. Mass flow, molecular hopping, distribution patterns and macromolecular signalling.

    PubMed

    van Bel, Aart J E; Furch, Alexandra C U; Hafke, Jens B; Knoblauch, Michael; Patrick, John W

    2011-10-01

    This review speculates on correlations between mass flow in sieve tubes and the distribution of photoassimilates and macromolecular signals. Since micro- (low-molecular compounds) and macromolecules are withdrawn from, and released into, the sieve-tube sap at various rates, distribution patterns of these compounds do not strictly obey mass-flow predictions. Due to serial release and retrieval transport steps executed by sieve tube plasma membranes, micromolecules are proposed to "hop" between sieve element/companion cell complexes and phloem parenchyma cells under source-limiting conditions (apoplasmic hopping). Under sink-limiting conditions, micromolecules escape from sieve tubes via pore-plasmodesma units and are temporarily stored. It is speculated that macromolecules "hop" between sieve elements and companion cells using plasmodesmal trafficking mechanisms (symplasmic hopping). We explore how differential tagging may influence distribution patterns of macromolecules and how their bidirectional movement could arise. Effects of exudation techniques on the macromolecular composition of sieve-tube sap are discussed. PMID:21889037

  17. The human osmoregulatory Na{sup +}/myo-inositol cotransporter gene (SLC5A3): Molecular cloning and localization to chromosome 21

    SciTech Connect

    Berry, G.T.; Mallee, J.J.; Muenke, M.

    1995-01-20

    A human Na{sup +}/myo-inositol cotransporter (SLC5A3) gene was cloned; sequencing revealed a single intron-free open reading frame of 2157 nucleotides. Containing 718 amino acid residues, the predicted protein is highly homologous to the product of the canine osmoregulatory SLC5A3 gene. The SLC5A3 protein is number 3 of the solute carrier family 5 and was previously designated SMIT. Using fluorescence in situ hybridization, the human SLC5A3 gene was localized to band q22 on chromosome 21. Many tissues including brain demonstrate gene expression. The inability of a trisomic 21 cell to downregulate expression of three copies of this osmoregulatory gene could result in increased flux of both myo-inositol and Na{sup +} across the plasma membrane. The potential consequences include perturbations in the cell membrane potential and tissue osmolyte levels. The SLC5A3 gene may play a role in the pathogenesis of Down syndrome. 54 refs., 4 figs.

  18. Visualization of three-dimensional liquid flow on sieve trays

    NASA Astrophysics Data System (ADS)

    Wang, Xiaoling

    2004-03-01

    This paper presents the simulated result of three-dimensional liquid velocity profile on sieve trays by using a computational flow dynamics (CFD) model with considerations of volume fraction of gas and liquid and the interfacial forces. The Κ-ɛ equation is used for the closure of basic equations. For the first time the three-dimensional liquid flow on a distillation column with ten trays under total reflux is visualized. The simulation was carried out with an Origin 200 Server Workstation of SGI Company using Star-CD V3.1 program. Simulation provides the detailed information of the distribution of 3D liquid velocity on the distillation column.

  19. Centrifugal Size-Separation Sieve for Granular Materials

    NASA Technical Reports Server (NTRS)

    Walton, Otis (Inventor); Dreyer, Christopher (Inventor); Riedel, Edward (Inventor)

    2015-01-01

    A centrifugal sieve and method utilizes centrifugal force in rapidly-rotated cylindrical or conical screens as the primary body force contributing to size segregation. Within the centrifugal acceleration field, vibration and/or shearing flows are induced to facilitate size segregation and eventual separation of the fines from the coarse material. Inside a rotating cylindrical or conical screen, a separately-rotated screw auger blade can be used to transport material along the rotating cylinder or conical wall and to induce shearing in the material.

  20. Nios II hardware acceleration of the epsilon quadratic sieve algorithm

    NASA Astrophysics Data System (ADS)

    Meyer-Bäse, Uwe; Botella, Guillermo; Castillo, Encarnacion; García, Antonio

    2010-04-01

    The quadratic sieve (QS) algorithm is one of the most powerful algorithms to factor large composite primes used to break RSA cryptographic systems. The hardware structure of the QS algorithm seems to be a good fit for FPGA acceleration. Our new ɛ-QS algorithm further simplifies the hardware architecture making it an even better candidate for C2H acceleration. This paper shows our design results in FPGA resource and performance when implementing very long arithmetic on the Nios microprocessor platform with C2H acceleration for different libraries (GMP, LIP, FLINT, NRMP) and QS architecture choices for factoring 32-2048 bit RSA numbers.

  1. Medical sieve: a cognitive assistant for radiologists and cardiologists

    NASA Astrophysics Data System (ADS)

    Syeda-Mahmood, T.; Walach, E.; Beymer, D.; Gilboa-Solomon, F.; Moradi, M.; Kisilev, P.; Kakrania, D.; Compas, C.; Wang, H.; Negahdar, R.; Cao, Y.; Baldwin, T.; Guo, Y.; Gur, Y.; Rajan, D.; Zlotnick, A.; Rabinovici-Cohen, S.; Ben-Ari, R.; Guy, Amit; Prasanna, P.; Morey, J.; Boyko, O.; Hashoul, S.

    2016-03-01

    Radiologists and cardiologists today have to view large amounts of imaging data relatively quickly leading to eye fatigue. Further, they have only limited access to clinical information relying mostly on their visual interpretation of imaging studies for their diagnostic decisions. In this paper, we present Medical Sieve, an automated cognitive assistant for radiologists and cardiologists designed to help in their clinical decision-making. The sieve is a clinical informatics system that collects clinical, textual and imaging data of patients from electronic health records systems. It then analyzes multimodal content to detect anomalies if any, and summarizes the patient record collecting all relevant information pertinent to a chief complaint. The results of anomaly detection are then fed into a reasoning engine which uses evidence from both patient-independent clinical knowledge and large-scale patient-driven similar patient statistics to arrive at potential differential diagnosis to help in clinical decision making. In compactly summarizing all relevant information to the clinician per chief complaint, the system still retains links to the raw data for detailed review providing holistic summaries of patient conditions. Results of clinical studies in the domains of cardiology and breast radiology have already shown the promise of the system in differential diagnosis and imaging studies summarization.

  2. Molecular separation method and apparatus

    DOEpatents

    Villa-Aleman, Eliel

    1996-01-01

    A method and apparatus for separating a gaseous mixture of chemically identical but physically different molecules based on their polarities. The gaseous mixture of molecules is introduced in discrete quantities into the proximal end of a porous glass molecular. The molecular sieve is exposed to microwaves to excite the molecules to a higher energy state from a lower energy state, those having a higher dipole moment being excited more than those with a lower energy state. The temperature of the sieve kept cold by a flow of liquid nitrogen through a cooling jacket so that the heat generated by the molecules colliding with the material is transferred away from the material. The molecules thus alternate between a higher energy state and a lower one, with the portion of molecules having the higher dipole moment favored over the others. The former portion can then be extracted separately from the distal end of the molecular sieve.

  3. A method to engineer phase-encoded photon sieve for intensity pattern generations

    NASA Astrophysics Data System (ADS)

    Li, Zhenhua; Ma, Li; Gao, Yaru; Liu, Chunxiang; Xu, Shicai; Zhang, Meina; Cheng, Chuanfu

    2015-11-01

    We propose a novel type of photon sieve where phases of its sieved waves are encoded as radial positions of the pinholes and use such phase-encoded sieves for generating designed intensity patterns in Fresnel domain. The sieve pinholes are arranged around Fresnel-rings to eliminate the quadratic Fresnel phase factor of diffraction of the sieved waves, leading the wave propagation to be equivalent to Fraunhofer diffraction. The pinholes take constant size in this paper and realize equal amplitude in the multiple sieved waves. Their positions are adjusted radially from corresponding rings to encode wave phases, taking effect by resulting in different optical paths from them to the observation plane origin. Then along with wave propagation, the encoded phases are decoded and the required phase differences are obtained in the discrete waves. We first conduct numerical simulations to show satisfactory performance of such phase-encoded photon sieves in generating arbitrarily designed intensity patterns and describe the quality of the reconstructed patterns. Then for qualitatively verifying the phase-encoding method, we experimentally fabricate three such sieves with relatively small pinhole number and obtain the designed patterns.

  4. Molecular analysis of HEXA gene in Argentinean patients affected with Tay-Sachs disease: possible common origin of the prevalent c.459+5A>G mutation.

    PubMed

    Zampieri, Stefania; Montalvo, Annalisa; Blanco, Mariana; Zanin, Irene; Amartino, Hernan; Vlahovicek, Kristian; Szlago, Marina; Schenone, Andrea; Pittis, Gabriela; Bembi, Bruno; Dardis, Andrea

    2012-05-15

    Tay-Sachs disease (TSD) is a recessively inherited disorder caused by the deficient activity of hexosaminidase A due to mutations in the HEXA gene. Up to date there is no information regarding the molecular genetics of TSD in Argentinean patients. In the present study we have studied 17 Argentinean families affected by TSD, including 20 patients with the acute infantile form and 3 with the sub-acute form. Overall, we identified 14 different mutations accounting for 100% of the studied alleles. Eight mutations were novel: 5 were single base changes leading to drastic residue changes or truncated proteins, 2 were small deletions and one was an intronic mutation that may cause a splicing defect. Although the spectrum of mutations was highly heterogeneous, a high frequency of the c.459+5G>A mutation, previously described in different populations was found among the studied cohort. Haplotype analysis suggested that in these families the c.459+5G>A mutation might have arisen by a single mutational event.

  5. Molecular analysis of HEXA gene in Argentinean patients affected with Tay-Sachs disease: possible common origin of the prevalent c.459+5A>G mutation.

    PubMed

    Zampieri, Stefania; Montalvo, Annalisa; Blanco, Mariana; Zanin, Irene; Amartino, Hernan; Vlahovicek, Kristian; Szlago, Marina; Schenone, Andrea; Pittis, Gabriela; Bembi, Bruno; Dardis, Andrea

    2012-05-15

    Tay-Sachs disease (TSD) is a recessively inherited disorder caused by the deficient activity of hexosaminidase A due to mutations in the HEXA gene. Up to date there is no information regarding the molecular genetics of TSD in Argentinean patients. In the present study we have studied 17 Argentinean families affected by TSD, including 20 patients with the acute infantile form and 3 with the sub-acute form. Overall, we identified 14 different mutations accounting for 100% of the studied alleles. Eight mutations were novel: 5 were single base changes leading to drastic residue changes or truncated proteins, 2 were small deletions and one was an intronic mutation that may cause a splicing defect. Although the spectrum of mutations was highly heterogeneous, a high frequency of the c.459+5G>A mutation, previously described in different populations was found among the studied cohort. Haplotype analysis suggested that in these families the c.459+5G>A mutation might have arisen by a single mutational event. PMID:22441121

  6. Mechanisms of recirculating liquid flow on distillation sieve plates

    SciTech Connect

    Biddulph, M.W. . Dept. of Chemical Engineering); Burton, A.C. )

    1994-11-01

    This paper describes an experimental investigation into the phenomenon of flow recirculation on distillation sieve trays. A novel dye injection technique has been applied to a 1.81 m air-water simulation column and has yielded new information concerning the nature of the boundary layer of gas-liquid biphase as it detaches from the column wall. The study has shown that recirculation is strongly influenced by inlet conditions. A critical factor is the underflow clearance between the inlet downcomer apron and the tray floor. As this clearance is increased, the size of the recirculating zones passes through a minimum, indicating the existence of two different mechanisms responsible for the nonuniform flow patterns. A significant implication of this work is that tray designers may minimize the impact of recirculating on mass transfer efficiency by appropriate choice of underflow clearance.

  7. A rhenium complex doped in a silica molecular sieve for molecular oxygen sensing: Construction and characterization

    NASA Astrophysics Data System (ADS)

    Yang, Xiaozhou; Li, Yanxiao

    2016-01-01

    This paper reported a diamine ligand and its Re(I) complex for potential application in oxygen sensing. The novelty of this diamine ligand localized at its increased conjugation chain which had a typical electron-withdrawing group of 1,3,4-oxadiazole. Electronic distribution of excited electrons and their lifetime were supposed to be increased, favoring oxygen sensing collision. This hypothesis was confirmed by single crystal analysis, theoretical calculation and photophysical measurement. It was found that this Re(I) complex had a long-lived emission peaking at 545 nm, favoring sensing application. By doping this complex into a silica matrix MCM-41, oxygen sensing performance and mechanism of the resulting composites were discussed in detail. Non-linear Stern-Volmer working curves were observed with maximum sensitivity of 5.54 and short response time of ~ 6 s.

  8. Clast-contact conglomerates in submarine canyons: possible subaqueous sieve deposits

    SciTech Connect

    Fitzgerald, M.S.

    1987-05-01

    Thick, coarse, clast-contact conglomerates in submarine canyon fill have previously been attributed to rock-fall, grain-flow, or winnowing processes. However, these processes do not adequately explain some thick conglomeratic sequences. The proposed process of subaqueous sieve deposition could account for these clast-contact conglomerates. Subaerial sieve deposition has been documented on small-scale fan models and on alluvial fans. A subaerial sieve deposit begins as a debris flow which at some point freezes up. The matrix is then lost by subsequent filtration or outflow, and the emplacement of a clast-contact gravel ensues. A subaqueous sieve deposit would be slightly modified in that the matrix would not be lost by filtration into the submarine canyon floor, but rather by outflow at the terminus of the lobe immediately after deposition, or possibly from the top and/or sides of the freezing flow mass during transport. Besides forming in submarine canyons, subaqueous sieve deposits might also occur in paralic, submarine fan channel, and base-of-the-slope settings. In substantiating the existence of subaqueous sieve deposits, the sedimentary structures and grain-size data from recent sieve deposits on alluvial fans are compared to those of ancient submarine canyon deposits. Numerous similarities are found supporting this new method of deposition. Some discrepancies are encountered, but these are expected due to modifications caused by an aqueous medium.

  9. Biofuel Manufacturing from Woody Biomass: Effects of Sieve Size Used in Biomass Size Reduction

    PubMed Central

    Zhang, Meng; Song, Xiaoxu; Deines, T. W.; Pei, Z. J.; Wang, Donghai

    2012-01-01

    Size reduction is the first step for manufacturing biofuels from woody biomass. It is usually performed using milling machines and the particle size is controlled by the size of the sieve installed on a milling machine. There are reported studies about the effects of sieve size on energy consumption in milling of woody biomass. These studies show that energy consumption increased dramatically as sieve size became smaller. However, in these studies, the sugar yield (proportional to biofuel yield) in hydrolysis of the milled woody biomass was not measured. The lack of comprehensive studies about the effects of sieve size on energy consumption in biomass milling and sugar yield in hydrolysis process makes it difficult to decide which sieve size should be selected in order to minimize the energy consumption in size reduction and maximize the sugar yield in hydrolysis. The purpose of this paper is to fill this gap in the literature. In this paper, knife milling of poplar wood was conducted using sieves of three sizes (1, 2, and 4 mm). Results show that, as sieve size increased, energy consumption in knife milling decreased and sugar yield in hydrolysis increased in the tested range of particle sizes. PMID:22665985

  10. Biofuel manufacturing from woody biomass: effects of sieve size used in biomass size reduction.

    PubMed

    Zhang, Meng; Song, Xiaoxu; Deines, T W; Pei, Z J; Wang, Donghai

    2012-01-01

    Size reduction is the first step for manufacturing biofuels from woody biomass. It is usually performed using milling machines and the particle size is controlled by the size of the sieve installed on a milling machine. There are reported studies about the effects of sieve size on energy consumption in milling of woody biomass. These studies show that energy consumption increased dramatically as sieve size became smaller. However, in these studies, the sugar yield (proportional to biofuel yield) in hydrolysis of the milled woody biomass was not measured. The lack of comprehensive studies about the effects of sieve size on energy consumption in biomass milling and sugar yield in hydrolysis process makes it difficult to decide which sieve size should be selected in order to minimize the energy consumption in size reduction and maximize the sugar yield in hydrolysis. The purpose of this paper is to fill this gap in the literature. In this paper, knife milling of poplar wood was conducted using sieves of three sizes (1, 2, and 4 mm). Results show that, as sieve size increased, energy consumption in knife milling decreased and sugar yield in hydrolysis increased in the tested range of particle sizes.

  11. Shape-selective sieving layers on an oxide catalyst surface.

    PubMed

    Canlas, Christian P; Lu, Junling; Ray, Natalie A; Grosso-Giordano, Nicolas A; Lee, Sungsik; Elam, Jeffrey W; Winans, Randall E; Van Duyne, Richard P; Stair, Peter C; Notestein, Justin M

    2012-12-01

    New porous materials such as zeolites, metal-organic frameworks and mesostructured oxides are of immense practical utility for gas storage, separations and heterogeneous catalysis. Their extended pore structures enable selective uptake of molecules or can modify the product selectivity (regioselectivity or enantioselectivity) of catalyst sites contained within. However, diffusion within pores can be problematic for biomass and fine chemicals, and not all catalyst classes can be readily synthesized with pores of the correct dimensions. Here, we present a novel approach that adds reactant selectivity to existing, non-porous oxide catalysts by first grafting the catalyst particles with single-molecule sacrificial templates, then partially overcoating the catalyst with a second oxide through atomic layer deposition. This technique is used to create sieving layers of Al(2)O(3) (thickness, 0.4-0.7 nm) with 'nanocavities' (<2 nm in diameter) on a TiO(2) photocatalyst. The additional layers result in selectivity (up to 9:1) towards less hindered reactants in otherwise unselective, competitive photocatalytic oxidations and transfer hydrogenations. PMID:23174984

  12. Shape-selective sieving layers on an oxide catalyst surface

    NASA Astrophysics Data System (ADS)

    Canlas, Christian P.; Lu, Junling; Ray, Natalie A.; Grosso-Giordano, Nicolas A.; Lee, Sungsik; Elam, Jeffrey W.; Winans, Randall E.; van Duyne, Richard P.; Stair, Peter C.; Notestein, Justin M.

    2012-12-01

    New porous materials such as zeolites, metal-organic frameworks and mesostructured oxides are of immense practical utility for gas storage, separations and heterogeneous catalysis. Their extended pore structures enable selective uptake of molecules or can modify the product selectivity (regioselectivity or enantioselectivity) of catalyst sites contained within. However, diffusion within pores can be problematic for biomass and fine chemicals, and not all catalyst classes can be readily synthesized with pores of the correct dimensions. Here, we present a novel approach that adds reactant selectivity to existing, non-porous oxide catalysts by first grafting the catalyst particles with single-molecule sacrificial templates, then partially overcoating the catalyst with a second oxide through atomic layer deposition. This technique is used to create sieving layers of Al2O3 (thickness, 0.4-0.7 nm) with ‘nanocavities’ (<2 nm in diameter) on a TiO2 photocatalyst. The additional layers result in selectivity (up to 9:1) towards less hindered reactants in otherwise unselective, competitive photocatalytic oxidations and transfer hydrogenations.

  13. Sieve of Eratosthenes benchmarks for the Z8 FORTH microcontroller

    SciTech Connect

    Edwards, R.

    1989-02-01

    This report presents benchmarks for the Z8 FORTH microcontroller system that ORNL uses extensively in proving concepts and developing prototype test equipment for the Smart House Project. The results are based on the sieve of Eratosthenes algorithm, a calculation used extensively to rate computer systems and programming languages. Three benchmark refinements are presented,each showing how the execution speed of a FORTH program can be improved by use of a particular optimization technique. The last version of the FORTH benchmark shows that optimization is worth the effort: It executes 20 times faster than the Gilbreaths' widely-published FORTH benchmark program. The National Association of Home Builders Smart House Project is a cooperative research and development effort being undertaken by American home builders and a number of major corporations serving the home building industry. The major goal of the project is to help the participating organizations incorporate advanced technology in communications,energy distribution, and appliance control products for American homes. This information is provided to help project participants use the Z8 FORTH prototyping microcontroller in developing Smart House concepts and equipment. The discussion is technical in nature and assumes some experience with microcontroller devices and the techniques used to develop software for them. 7 refs., 5 tabs.

  14. Experimental testing of focusing properties of subwavelength photon sieves using exposure method

    NASA Astrophysics Data System (ADS)

    Jiang, Wenbo; Zhang, Xiaohua

    2016-04-01

    An exposure method is proposed to test the focusing properties of subwavelength photon sieves. To solve the problems caused by the subwavelength photon sieves (such as short focal length and small focal spot size), a grating moiré fringe phase detection technique and a microcontact sensor with lead zirconium titanate (PZT) stepping hybrid technique are used in the experimental setup. The focusing properties of the subwavelength photon sieves are tested by this setup. The results show that the focal length and the focal spot size are close to the designed value. Finally, the intensity distribution of the focal spot is proposed. This research result will be beneficial for understanding the focusing properties of subwavelength photon sieves, will help us to improve the imaging quality, and will provide a good experimental basis for practical applications in the nanolithography field.

  15. Centrifugal Sieve for Gravity-Level-Independent Size Segregation of Granular Materials

    NASA Technical Reports Server (NTRS)

    Walton, Otis R.; Dreyer, Christopher; Riedel, Edward

    2013-01-01

    Conventional size segregation or screening in batch mode, using stacked vibrated screens, is often a time-consuming process. Utilization of centrifugal force instead of gravity as the primary body force can significantly shorten the time to segregate feedstock into a set of different-sized fractions. Likewise, under reduced gravity or microgravity, a centrifugal sieve system would function as well as it does terrestrially. When vibratory and mechanical blade sieving screens designed for terrestrial conditions were tested under lunar gravity conditions, they did not function well. The centrifugal sieving design of this technology overcomes the issues that prevented sieves designed for terrestrial conditions from functioning under reduced gravity. These sieves feature a rotating outer (cylindrical or conical) screen wall, rotating fast enough for the centrifugal forces near the wall to hold granular material against the rotating screen. Conventional centrifugal sieves have a stationary screen and rapidly rotating blades that shear the granular solid near the stationary screen, and effect the sieving process assisted by the airflow inside the unit. The centrifugal sieves of this new design may (or may not) have an inner blade or blades, moving relative to the rotating wall screen. Some continuous flow embodiments would have no inner auger or blades, but achieve axial motion through vibration. In all cases, the shearing action is gentler than conventional centrifugal sieves, which have very high velocity differences between the stationary outer screen and the rapidly rotating blades. The new design does not depend on airflow in the sieving unit, so it will function just as well in vacuum as in air. One advantage of the innovation for batch sieving is that a batch-mode centrifugal sieve may accomplish the same sieving operation in much less time than a conventional stacked set of vibrated screens (which utilize gravity as the primary driving force for size separation

  16. Dr. Grant Heikan examines lunar material in sieve from sample container

    NASA Technical Reports Server (NTRS)

    1969-01-01

    Dr. Grant Heikan, Manned Spacecraft Center and a Lunar Sample preliminary Examination Team member, examines lunar material in a sieve from the bulk sample container which was opened in the Biopreparation Laboratory of the Lunar Receiving Laboratory.

  17. Tuning Pore Size in Square-Lattice Coordination Networks for Size-Selective Sieving of CO2.

    PubMed

    Chen, Kai-Jie; Madden, David G; Pham, Tony; Forrest, Katherine A; Kumar, Amrit; Yang, Qing-Yuan; Xue, Wei; Space, Brian; Perry, John J; Zhang, Jie-Peng; Chen, Xiao-Ming; Zaworotko, Michael J

    2016-08-22

    Porous materials capable of selectively capturing CO2 from flue-gases or natural gas are of interest in terms of rising atmospheric CO2 levels and methane purification. Size-exclusive sieving of CO2 over CH4 and N2 has rarely been achieved. Herein we show that a crystal engineering approach to tuning of pore-size in a coordination network, [Cu(quinoline-5-carboxyate)2 ]n (Qc-5-Cu) ena+bles ultra-high selectivity for CO2 over N2 (SCN ≈40 000) and CH4 (SCM ≈3300). Qc-5-Cu-sql-β, a narrow pore polymorph of the square lattice (sql) coordination network Qc-5-Cu-sql-α, adsorbs CO2 while excluding both CH4 and N2 . Experimental measurements and molecular modeling validate and explain the performance. Qc-5-Cu-sql-β is stable to moisture and its separation performance is unaffected by humidity.

  18. Tuning Pore Size in Square-Lattice Coordination Networks for Size-Selective Sieving of CO2.

    PubMed

    Chen, Kai-Jie; Madden, David G; Pham, Tony; Forrest, Katherine A; Kumar, Amrit; Yang, Qing-Yuan; Xue, Wei; Space, Brian; Perry, John J; Zhang, Jie-Peng; Chen, Xiao-Ming; Zaworotko, Michael J

    2016-08-22

    Porous materials capable of selectively capturing CO2 from flue-gases or natural gas are of interest in terms of rising atmospheric CO2 levels and methane purification. Size-exclusive sieving of CO2 over CH4 and N2 has rarely been achieved. Herein we show that a crystal engineering approach to tuning of pore-size in a coordination network, [Cu(quinoline-5-carboxyate)2 ]n (Qc-5-Cu) ena+bles ultra-high selectivity for CO2 over N2 (SCN ≈40 000) and CH4 (SCM ≈3300). Qc-5-Cu-sql-β, a narrow pore polymorph of the square lattice (sql) coordination network Qc-5-Cu-sql-α, adsorbs CO2 while excluding both CH4 and N2 . Experimental measurements and molecular modeling validate and explain the performance. Qc-5-Cu-sql-β is stable to moisture and its separation performance is unaffected by humidity. PMID:27439315

  19. Molecular Models of STAT5A Tetramers Complexed to DNA Predict Relative Genome-Wide Frequencies of the Spacing between the Two Dimer Binding Motifs of the Tetramer Binding Sites

    PubMed Central

    Sathyanarayana, Bangalore K.; Li, Peng; Lin, Jian-Xin; Leonard, Warren J.

    2016-01-01

    STAT proteins bind DNA as dimers and tetramers to control cellular development, differentiation, survival, and expansion. The tetramer binding sites are comprised of two dimer-binding sites repeated in tandem. The genome-wide distribution of the spacings between the dimer binding sites shows a distinctive, non-random pattern. Here, we report on estimating the feasibility of building possible molecular models of STAT5A tetramers bound to a DNA double helix with all possible spacings between the dimer binding sites. We found that the calculated feasibility estimates correlated well with the experimentally measured frequency of tetramer-binding sites. This suggests that the feasibility of forming the tetramer complex was a major factor in the evolution of this DNA sequence variation. PMID:27537504

  20. Molecular Models of STAT5A Tetramers Complexed to DNA Predict Relative Genome-Wide Frequencies of the Spacing between the Two Dimer Binding Motifs of the Tetramer Binding Sites.

    PubMed

    Sathyanarayana, Bangalore K; Li, Peng; Lin, Jian-Xin; Leonard, Warren J; Lee, Byungkook

    2016-01-01

    STAT proteins bind DNA as dimers and tetramers to control cellular development, differentiation, survival, and expansion. The tetramer binding sites are comprised of two dimer-binding sites repeated in tandem. The genome-wide distribution of the spacings between the dimer binding sites shows a distinctive, non-random pattern. Here, we report on estimating the feasibility of building possible molecular models of STAT5A tetramers bound to a DNA double helix with all possible spacings between the dimer binding sites. We found that the calculated feasibility estimates correlated well with the experimentally measured frequency of tetramer-binding sites. This suggests that the feasibility of forming the tetramer complex was a major factor in the evolution of this DNA sequence variation. PMID:27537504

  1. Brownian Motion Rectifier: Continuous Sorting of Macromolecules in a Microfabricated Sieve

    NASA Astrophysics Data System (ADS)

    Chou, C. F.; Duke, T. A. J.; Chan, S. S.; Bakajin, O. B.; Austin, R. H.; Cox, E. C.

    1998-03-01

    A new method for separating biological macromolecules according to size has been proposed by Duke and Austin (T.A.J. Duke and R.H. Austin, preprint (1997).). A fine stream of molecules is transported through a microfabricated sieve, etched from a silicon chip by photolithography. The sieve consists of a periodic array of oblong obstacles, oriented at an angle to the direction of flow. The spatial asymmetry and the broken time-reversal symmetry (imposed by the flow) cause the Brownian motion of the molecules to be rectified. Since the effect depends on the thermal motion, molecules with different diffusion coefficients are deflected by different amounts, and consequently a mixture of molecules is sorted according to size. Our preliminary results in sorting a mixture of DNA in such a sieve will be presented.

  2. Use of thermal sieve to allow optical testing of cryogenic optical systems.

    PubMed

    Kim, Dae Wook; Cai, Wenrui; Burge, James H

    2012-05-21

    Full aperture testing of large cryogenic optical systems has been impractical due to the difficulty of operating a large collimator at cryogenic temperatures. The Thermal Sieve solves this problem by acting as a thermal barrier between an ambient temperature collimator and the cryogenic system under test. The Thermal Sieve uses a set of thermally controlled baffles with array of holes that are lined up to pass the light from the collimator without degrading the wavefront, while attenuating the thermal background by nearly 4 orders of magnitude. This paper provides the theory behind the Thermal Sieve system, evaluates the optimization for its optical and thermal performance, and presents the design and analysis for a specific system.

  3. Laser Diffraction Techniques Replace Sieving for Lunar Soil Particle Size Distribution Data

    NASA Technical Reports Server (NTRS)

    Cooper, Bonnie L.; Gonzalez, C. P.; McKay, D. S.; Fruland, R. L.

    2012-01-01

    Sieving was used extensively until 1999 to determine the particle size distribution of lunar samples. This method is time-consuming, and requires more than a gram of material in order to obtain a result in which one may have confidence. This is demonstrated by the difference in geometric mean and median for samples measured by [1], in which a 14-gram sample produced a geometric mean of approx.52 micrometers, whereas two other samples of 1.5 grams resulted in gave means of approx.63 and approx.69 micrometers. Sample allocations for sieving are typically much smaller than a gram, and many of the sample allocations received by our lab are 0.5 to 0.25 grams in mass. Basu [2] has described how the finest fraction of the soil is easily lost in the sieving process, and this effect is compounded when sample sizes are small.

  4. Direct Measurement of Sieve Tube Turgor Pressure Using Severed Aphid Stylets 1

    PubMed Central

    Wright, John P.; Fisher, Donald B.

    1980-01-01

    Turgor pressure in individual sieve tubes was measured directly by gluing capillary micromanometers over exuding aphid stylets with cyanoac-rylate adhesive. Pressures of up to 10 bars were measured in sieve tubes of Salix babylonica, with an estimated accuracy of ± 0.3 bars or better. For comparison with the direct measurements of sieve tube turgor, calculated values of turgor pressure were also obtained from the difference between leaf water potential and phloem exudate solute potential, estimated from its refractive index and sucrose content. In most cases the measured turgor pressure was greater than the calculated value. The discrepancy between the two values was most likely due to the presence of appreciable concentrations of potassium and amino acids in the phloem exudate. PMID:16661346

  5. Live Imaging of Companion Cells and Sieve Elements in Arabidopsis Leaves

    PubMed Central

    Cayla, Thibaud; Batailler, Brigitte; Le Hir, Rozenn; Revers, Frédéric; Anstead, James A.; Thompson, Gary A.; Grandjean, Olivier; Dinant, Sylvie

    2015-01-01

    The phloem is a complex tissue composed of highly specialized cells with unique subcellular structures and a compact organization that is challenging to study in vivo at cellular resolution. We used confocal scanning laser microscopy and subcellular fluorescent markers in companion cells and sieve elements, for live imaging of the phloem in Arabidopsis leaves. This approach provided a simple framework for identifying phloem cell types unambiguously. It highlighted the compactness of the meshed network of organelles within companion cells. By contrast, within the sieve elements, unknown bodies were observed in association with the PP2-A1:GFP, GFP:RTM1 and RTM2:GFP markers at the cell periphery. The phloem lectin PP2-A1:GFP marker was found in the parietal ground matrix. Its location differed from that of the P-protein filaments, which were visualized with SEOR1:GFP and SEOR2:GFP. PP2-A1:GFP surrounded two types of bodies, one of which was identified as mitochondria. This location suggested that it was embedded within the sieve element clamps, specific structures that may fix the organelles to each another or to the plasma membrane in the sieve tubes. GFP:RTM1 was associated with a class of larger bodies, potentially corresponding to plastids. PP2-A1:GFP was soluble in the cytosol of immature sieve elements. The changes in its subcellular localization during differentiation provide an in vivo blueprint for monitoring this process. The subcellular features obtained with these companion cell and sieve element markers can be used as landmarks for exploring the organization and dynamics of phloem cells in vivo. PMID:25714357

  6. Computational image formation with photon sieves for milli-arcsecond solar imaging

    NASA Astrophysics Data System (ADS)

    Oktem, Figen S.; Kamalabadi, Farzad; Davila, Joseph

    2016-07-01

    A photon sieve is a modification of a Fresnel zone plate in which open zones are replaced by a large number of circular holes. This diffractive imaging element is specially suited to observations at UV and x-ray wavelengths where refractive lenses are not available due to strong absorption of materials, and reflective mirrors are difficult to manufacture with sufficient surface figure accuracy to achieve diffraction-limited resolution. On the other hand, photon sieves enable diffraction-limited imaging with much more relaxed tolerances than conventional imaging technology. In this presentation, we present the capabilities of an instrument concept that is based on computational image formation with photon sieves. The instrument enables high-resolution spectral imaging by distributing the imaging task between a photon sieve system and a computational method. A photon sieve coupled with a moving detector provides measurements from multiple planes. Then computational image formation, which involves deconvolution, is performed in a Bayesian estimation framework to reconstruct the multi-spectral images from these measurements. In addition to diffraction-limited high spatial resolution enabled by photon sieves, this instrument can also achieve higher spectral resolution than the conventional spectral imagers, since the technique offers the possibility of separating nearby spectral components that would not otherwise be possible using wavelength filters. Here, the promising capabilities and the imaging performance are shown for imaging the solar corona at EUV wavelengths. The effectiveness of various potential observing scenarios, the effects of interfering emission lines, and the appropriate form of the cost function for image deconvolution are examined.

  7. Effect of liquid channeling on a 1.8-m distillation sieve tray

    SciTech Connect

    Proctor, S.J.; Biddulph, M.W.; Krishnamurthy, K.R.

    1998-06-01

    This paper describes an experimental investigation designed to establish the extent of the effects of liquid channeling and stagnant zones on the efficiency of a 1.8-m diameter sieve tray. The method used is to compare performance, in the same column and using the same system, with a novel tray which is known, from hydraulic studies, to remove stagnant zones. It is found that there is an observable loss in efficiency in the sieve tray, particularly at heavy loadings, and this will have implications for designers specifying high-capacity trays for new or upgraded columns.

  8. Microfluidic sieve using intertwined, free-standing carbon nanotube mesh as active medium

    DOEpatents

    Bakajin, Olgica; Noy, Aleksandr

    2007-11-06

    A microfluidic sieve having a substrate with a microfluidic channel, and a carbon nanotube mesh. The carbon nanotube mesh is formed from a plurality of intertwined free-standing carbon nanotubes which are fixedly attached within the channel for separating, concentrating, and/or filtering molecules flowed through the channel. In one embodiment, the microfluidic sieve is fabricated by providing a substrate having a microfluidic channel, and growing the intertwined free-standing carbon nanotubes from within the channel to produce the carbon nanotube mesh attached within the channel.

  9. Chronic recording of regenerating VIIIth nerve axons with a sieve electrode

    NASA Technical Reports Server (NTRS)

    Mensinger, A. F.; Anderson, D. J.; Buchko, C. J.; Johnson, M. A.; Martin, D. C.; Tresco, P. A.; Silver, R. B.; Highstein, S. M.

    2000-01-01

    A micromachined silicon substrate sieve electrode was implanted within transected toadfish (Opsanus tau) otolith nerves. High fidelity, single unit neural activity was recorded from seven alert and unrestrained fish 30 to 60 days after implantation. Fibrous coatings of genetically engineered bioactive protein polymers and nerve guide tubes increased the number of axons regenerating through the electrode pores when compared with controls. Sieve electrodes have potential as permanent interfaces to the nervous system and to bridge missing connections between severed or damaged nerves and muscles. Recorded impulses might also be amplified and used to control prosthetic devices.

  10. The movement protein of cucumber mosaic virus traffics into sieve elements in minor veins of nicotiana clevelandii

    PubMed Central

    Blackman, LM; Boevink, P; Cruz, SS; Palukaitis, P; Oparka, KJ

    1998-01-01

    The location of the 3a movement protein (MP) of cucumber mosaic virus (CMV) was studied by quantitative immunogold labeling of the wild-type 3a MP in leaves of Nicotiana clevelandii infected by CMV as well as by using a 3a-green fluorescent protein (GFP) fusion expressed from a potato virus X (PVX) vector. Whether expressed from CMV or PVX, the 3a MP targeted plasmodesmata and accumulated in the central cavity of the pore. Within minor veins, the most extensively labeled plasmodesmata were those connecting sieve elements and companion cells. In addition to targeting plasmodesmata, the 3a MP accumulated in the parietal layer of mature sieve elements. Confocal imaging of cells expressing the 3a-GFP fusion protein showed that the 3a MP assembled into elaborate fibrillar formations in the sieve element parietal layer. The ability of 3a-GFP, expressed from PVX rather than CMV, to enter sieve elements demonstrates that neither the CMV RNA nor the CMV coat protein is required for trafficking of the 3a MP into sieve elements. CMV virions were not detected in plasmodesmata from CMV-infected tissue, although large CMV aggregates were often found in the parietal layer of sieve elements and were usually surrounded by 3a MP. These data suggest that CMV traffics into minor vein sieve elements as a ribonucleoprotein complex that contains the viral RNA, coat protein, and 3a MP, with subsequent viral assembly occurring in the sieve element parietal layer. PMID:9548980

  11. Impact of the carbon pore size and topology on the equilibrium quantum sieving of hydrogen isotopes at zero coverage and finite pressures.

    PubMed

    Kowalczyk, Piotr; Gauden, Piotr A; Terzyk, Artur P; Furmaniak, Sylwester

    2009-04-01

    Carbonaceous slit-shaped and square-shaped pores efficiently differentiate adsorbed hydrogen isotopes at 77 and 33 K. Extensive path integral Monte Carlo simulations revealed that the square-shaped carbon pores enhanced the selectivity of deuterium over hydrogen in comparison to equivalent slit-shaped carbon pores at zero coverage as well as at finite pressures (i.e. quantum sieving of hydrogen isotopes is pore-topology-dependent). We show that this enhancement of the D(2)/H(2) equilibrium selectivity results from larger localization of hydrogen isotopes in square-shaped pores. The operating pressures for efficient quantum sieving of hydrogen isotopes are strongly dependent on the topology as well as on the size of the carbon pores. However, for both considered carbon pore topologies the highest D(2)/H(2) separation factor is observed at zero-coverage limit. Depending on carbon pore size and topology we predicted monotonic decreasing and non-monotonic shape of the D(2)/H(2) equilibrium selectivity at finite pressures. For both kinds of carbonaceous pores of molecular sizes we predict high compression of hydrogen isotopes at 77 and 33 K (for example, the pore density of compressed hydrogen isotopes at 77 K and 0.25 MPa in a square-shaped carbon pore of size 2.6 Å exceeds 60 mmol cm(-3); for comparison, the liquid density of para-H(2) at 30 K and 30 MPa is 42 mmol cm(-3)). Finally, by direct comparison of simulation results with experimental data it is explained why 'ordinary' carbonaceous materials are not efficient quantum sieves.

  12. Alternative sieving method for extraction of light filth from cheeses: collaborative study.

    PubMed

    Nakashima, M J

    1994-01-01

    A collaborative study was conducted on an alternative sieving method for the extraction of light filth from cheeses. The alternative method was developed that is applicable to broad variety of cheeses. A 225 g test portion is dispersed in a solution of 5.7% HCl, Igepal CO-730, and Igepal DM-710. Digested cheese is wet-sieved on a No. 230 sieve. The residue is treated with Tergitol Anionic 4, transferred to 1% sodium lauryl sulfate solution, heated, and maintained at 65 degrees-75 degrees C for 10 min. The residue is washed with these 2 surfactants a maximum of 4 times until it is reduced to an amount that is filterable. The residue is filtered and the filter papers are examined microscopically at a magnification of ca 30x. Average recoveries by 9 collaborators for 3 spike levels of rat hairs (5, 10, and 15) were 80, 68, and 81%, respectively; for insect fragments (5, 15, and 30) recoveries were 97, 90, and 92%, respectively. The alternative sieving method for extraction of light filth from cheeses has been adopted first action by AOAC INTERNATIONAL. PMID:7950417

  13. Catalytic cracking of HDPE wastes to liquid fuel in the presence of siliceous mesoporous molecular sieves

    NASA Astrophysics Data System (ADS)

    Ramli, Anita; Majid, Noor Diana Abdul; Yusup, Suzana

    2014-10-01

    A siliceous gel was synthesized at 80°C and aged for 5 days at 120°C before it was dried at 120°C for 16 hours and calcined at 500 and 700°C. The calcined Na-Si-MMS samples were then undergone ion exchange with ammonia solution to form NH4- Si - MMS . All samples were characterized for their physicochemical properties using nitrogen (N2) adsorption-desorption isotherm for surface area and porosity; and temperature programme desorption of ammonia (TPD-NH3) for determination of acidity. The catalytic activity of all samples was tested in pyrolysis of high density polyethylene (HDPE) waste at catalyst to HDPE ratio of 0.2. The organic liquid product (OLP) collected was analysed using gas chromatography (GC). Results show that presence of Na-Si-MMS calcined at 500°C promotes the formation of gasoline-like product while presence of Na-Si-MMS calcined at 700°C promotes the formation of both diesel-like and kerosene-like products. On the other hand, presence of all NH4-Si-MMS catalysts promotes the formation of gasoline-like product. These show that the activation process of Si-MMS has a significant effect on the production of fuel-like product from pyrolysis of HDPE.

  14. Molecular sieve adsorbents and membranes for applications in the production of renewable fuels and chemicals

    NASA Astrophysics Data System (ADS)

    Ranjan, Rajiv

    Metal organic frameworks (MOF), a new class of porous materials, have emerged as promising candidate for gas storage, separation membrane and chemical sensors. We used secondary growth method to grow microporous metal organic framework (MMOF) films on porous alumina supports. Examination of the film using SEM and XRD showed that the crystals were well inter-grown and preferentially oriented. Gas permeation study showed that membranes were defect free and moderate selectivity was achieved for H2/N2 gas pairs. The next project had to do with ethanol production from lignocellulosic biomass as an alternate energy source. However, toxic inhibitors produced from the hydrolysis of biomass decrease ethanol yield during the fermentation process. We demonstrated the use of zeolites for the pretreatment of hydrolyzate in order to remove inhibitors like 5-Hydroxymethylfurfuraldehyde (HMF) and furfural from aqueous solution. Zeolites exhibit preferential adsorption of the inhibitors and in effect improve the ethanol yield during fermentation. Ideal Adsorbed Solution Theory (IAST) was also used to predict adsorption isotherms for HMF-furfural mixtures using single component adsorption data. We also studied production of HMF, a potential substitute as a building block for plastic and chemical production, from renewable biomass resources. Catalytic dehydration of fructose for HMF production faces problems like low conversion and yield. Dimethyl sulfoxide (DMSO) can be used as the solvent as well as the catalyst resulting in high HMF yield. We studied a reaction-separation system for this dehydration reaction where the product (HMF) could be recovered by selective adsorption on solid adsorbents from the reaction mixture.

  15. Reduction of nitrogen oxides with catalytic acid resistant aluminosilicate molecular sieves and ammonia

    DOEpatents

    Pence, Dallas T.; Thomas, Thomas R.

    1980-01-01

    Noxious nitrogen oxides in a waste gas stream such as the stack gas from a fossil-fuel-fired power generation plant or other industrial plant off-gas stream is catalytically reduced to elemental nitrogen and/or innocuous nitrogen oxides employing ammonia as reductant in the presence of a zeolite catalyst in the hydrogen or sodium form having pore openings of about 3 to 10 A.

  16. Optimization of Manganese Reduction in Biotreated POME onto 3A Molecular Sieve and Clinoptilolite Zeolites.

    PubMed

    Jami, Mohammed S; Rosli, Nurul-Shafiqah; Amosa, Mutiu K

    2016-06-01

    Availability of quality-certified water is pertinent to the production of food and pharmaceutical products. Adverse effects of manganese content of water on the corrosion of vessels and reactors necessitate that process water is scrutinized for allowable concentration levels before being applied in the production processes. In this research, optimization of the adsorption process conditions germane to the removal of manganese from biotreated palm oil mill effluent (BPOME) using zeolite 3A subsequent to a comparative adsorption with clinoptilolite was studied. A face-centered central composite design (FCCCD) of the response surface methodology (RSM) was adopted for the study. Analysis of variance (ANOVA) for response surface quadratic model revealed that the model was significant with dosage and agitation speed connoting the main significant process factors for the optimization. R(2) of 0.9478 yielded by the model was in agreement with predicted R(2). Langmuir and pseudo-second-order suggest the adsorption mechanism involved monolayer adsorption and cation exchanging.

  17. Probing silicon substitution in molecular sieves by plasma desorption mass spectrometry

    NASA Astrophysics Data System (ADS)

    Van Stipdonk, M. J.; von Heimburg, S. L.; Schweikert, E. A.

    1998-10-01

    Plasma desorption was used to produce secondary ion mass spectra from samples of unsubstituted and substituted aluminum phosphate materials. The yield of fingerprint ions representative of silicon oxide solids indicates that the incorporation of silicon into the material during synthesis and following calcination occurs via the formation of silicon-rich islands. Complementary X-ray photoelectron data provide supporting evidence that the surface of the substituted aluminum phosphate material becomes silicon rich and phosphorus depleted. No changes in the unsubstituted and substituted material with respect to composition and phase were detected using powder X-ray diffraction.

  18. LOW TEMPERATURE VOC COMBUSTION OVER MANGANESE, COBALT AND ZINC ALPO4 MOLECULAR SIEVES

    SciTech Connect

    Rosemarie Szostak

    2003-03-06

    The objective of this project was to prepare microporous aluminophosphates containing magnesium, manganese, cobalt and zinc (MeAPOs) and to evaluate their performance as oxidation catalysts for the removal of low levels of volatile organic compounds (VOCs) from gas streams. The tasks to be accomplished were as follows: (1) To develop reliable synthesis methods for metal aluminophosphates containing manganese, cobalt and zinc in their framework; (2) To characterize these materials for crystallinity, phase purity, the location and nature of the incorporated metal in the framework; and (3) To evaluate the materials for their catalytic activities in the oxidation of volatile organic environmental pollutants.

  19. Synthesis and application of different phthalocyanine molecular sieve catalyst for oxidative desulfurization

    SciTech Connect

    Zhao, Na; Li, Siwen; Wang, Jinyi; Zhang, Ronglan; Gao, Ruimin; Zhao, Jianshe; Wang, Junlong

    2015-05-15

    M{sub 2}(PcAN){sub 2} (M=Fe, Co, Ni, Cu, Zn and Mn) anchored onto W-HZSM-5 (M{sub 2}(PcAN){sub 2}–W-HZSM-5) or the M{sub 2}(PcTN){sub 2} doping W-HZSM-5 (M{sub 2}(PcTN){sub 2}/W-HZSM-5) were prepared and their catalytic performances were tested for oxidative desulfurization in the presence of oxygen. Thiophene (T), benzothiophene (BT), and dibenzothiophene (DBT) were considered as sulfur compounds. Among zeolite-based catalysts, the Cu{sub 2}(PcAN){sub 2}–W-HZSM-5 and Cu{sub 2}(PcTN){sub 2}/W-HZSM-5 showed superior desulfurization performance and the activity of selectivity followed the order: T>BT>DBT. The effects of phthalocyanine concentration were studied by UV–Vis and calcination temperature was obtained by TG-DSC for Cu{sub 2}(PcTN){sub 2}/W-HZSM-5. Catalysts were characterized by EA, IR, XRD, SEM, TEM, ICP, and N{sub 2} adsorption. Reaction time, temperature and the amount of catalyst were investigated as the important parameters for optimization of the reaction. Furthermore, a possible process of oxidative desulfurization and the reaction products were proposed. - Graphical abstract: The ODS reaction schematic shows the reaction mechanism of ultra-deep desulfurization. The sulfur compounds are oxidized to their corresponding sulfoxides or sulfones through the use of oxygen and catalysts. The reaction process of ultra-deep desulfurization. - Highlights: • A kind of novel catalyst for deep desulfurization was synthesized. • Cu{sub 2}(PcAN){sub 2}–W-HZSM-5 exhibits excellent catalytic performance for desulfurization. • The reaction conditions that affect desulfurization efficiency are investigated. • The reaction process of model sulfur compounds is proposed.

  20. Selective oxidation of hydrocarbons with O{sub 2} over chromium aluminophosphate-5 molecular sieve

    SciTech Connect

    Chen, J.D.; Sheldon, R.A.

    1995-04-15

    Chromium-substituted aluminophosphate-5 (CrAPO-5) is a heterogeneous, recyclable catalyst for the liquid phase autooxidation of hydrocarbons. CrAPO-5 catalyzed the autooxidation of cyclohexane at 115-130{degrees}C and 5 bar O{sub 2}, 20 bar air in the presence of a small amount of an alkyl hydroperoxide initiator, to afford cyclohexanone as the major product. Similarly, tetralin and indane were selectively oxidized to a 1-tetralone and 1-indanone, respectively, at 100{degrees}C and 1 bar O{sub 2}. Ethylbenzene was selectively converted to acetophenone, in the presence of sodium-exchanged CrAPO-5, at 130{degrees}C and 1 bar O{sub 2}. The CrAPO-5 catalyst was recycled four times without loss of activity or selectivity in the decomposition of cyclohexyl hydroperoxide. Evidence is presented to support a mechanism involving initial free radical autoxidation of the hydrocarbons followed by selective CrAPO-5-catalyzed intramolecular, heterolytic decomposition of the secondary alkyl hydroperoxide intermediate to the corresponding ketone and water. 26 refs., 7 figs., 5 tabs.

  1. Coal precursors for carbon molecular sieves. Quarterly report, October 1, 1995--December 31, 1995

    SciTech Connect

    Kopp, O.C.; Sparks, C.R.; Fuller, E.L. Jr.

    1995-12-29

    We have completed the remainder of our experimental work during this work period and have extracted much of the data from the many analyses performed. The temperatures at which selected thermal reactions occur and the temperatures at which monitored gases are released are in the process of being read from the computerized data. The data gleaned from the literature and the data we have gathered will be combined and examined using multiple regression analysis. During the course of our study we performed 55 BET analyses (including 12 fresh coal analyses, 10 coal samples that had been pyrolyzed in helium gas, 24 coal samples that had been activated using He-O2, 5 coal samples activated using He-H2O, and 4 coals samples activated using CO2). The number of BET analyses performed far exceeds the number we had planned when this project was first proposed. These analyses provide information that reveals the effects that factors such as the gas (or gas mixture) used for activation, the maximum temperature reached during activation, grain size, etc., have on the degree to which a coal is activated. These relationships are described, briefly, below. They will be discussed in detail in the Final Report. During this work period the FTIR equipment became available and we completed the FTIR analyses of all twelve (12) coal samples.

  2. Synthesis and application of different phthalocyanine molecular sieve catalyst for oxidative desulfurization

    NASA Astrophysics Data System (ADS)

    Zhao, Na; Li, Siwen; Wang, Jinyi; Zhang, Ronglan; Gao, Ruimin; Zhao, Jianshe; Wang, Junlong

    2015-05-01

    M2(PcAN)2 (M=Fe, Co, Ni, Cu, Zn and Mn) anchored onto W-HZSM-5 (M2(PcAN)2-W-HZSM-5) or the M2(PcTN)2 doping W-HZSM-5 (M2(PcTN)2/W-HZSM-5) were prepared and their catalytic performances were tested for oxidative desulfurization in the presence of oxygen. Thiophene (T), benzothiophene (BT), and dibenzothiophene (DBT) were considered as sulfur compounds. Among zeolite-based catalysts, the Cu2(PcAN)2-W-HZSM-5 and Cu2(PcTN)2/W-HZSM-5 showed superior desulfurization performance and the activity of selectivity followed the order: T>BT>DBT. The effects of phthalocyanine concentration were studied by UV-Vis and calcination temperature was obtained by TG-DSC for Cu2(PcTN)2/W-HZSM-5. Catalysts were characterized by EA, IR, XRD, SEM, TEM, ICP, and N2 adsorption. Reaction time, temperature and the amount of catalyst were investigated as the important parameters for optimization of the reaction. Furthermore, a possible process of oxidative desulfurization and the reaction products were proposed.

  3. Microwave-assisted fast vapor-phase transport synthesis of MnAPO-5 molecular sieves

    SciTech Connect

    Shao Hui; Yao Jianfeng; Ke Xuebin; Zhang Lixiong Xu Nanping

    2009-04-02

    MnAPO-5 was prepared by a microwave-assisted vapor-phase transport method at 180 deg. C in short times. The products were characterized by X-ray diffraction, scanning electron microscopy, Fourier transform infrared spectra, UV-vis spectroscopic measurement, NH{sub 3}-temperature-programmed desorption and esterification reaction. It was found that dry gels prepared with aluminum isopropoxide, phosphoric acid and manganese acetate could be transferred to MnAPO-5 in the vapors of triethylamine and water by the microwave-assisted vapor-phase transport method at 180 deg. C for less than 30 min. The crystallization time was greatly reduced by the microwave heating compared with the conventional heating. The resulting MnAPO-5 exhibited much smaller particle sizes, higher surface areas and slightly higher catalytic activity in the esterification of acetic acid and butyl alcohol than those prepared by the conventional vapor-phase transport method and hydrothermal synthesis.

  4. Textural and structural properties and surface acidity characterization of mesoporous silica-zirconia molecular sieves

    NASA Astrophysics Data System (ADS)

    Rodríguez-Castellón, E.; Jiménez-López, A.; Maireles-Torres, P.; Jones, D. J.; Rozière, J.; Trombetta, M.; Busca, G.; Lenarda, M.; Storaro, L.

    2003-11-01

    Homogeneous mesoporous zirconium-containing MCM-41 type silica were prepared by supramolecular templating and their textural and structural properties were studied using powder X-ray diffraction, N 2 porosimetry, atomic force microscopy, EXAFS, XPS, and UV-VIS-NIR diffuse reflectance spectroscopy. Their acid properties were also studied by using IR spectroscopy and by the use of catalytic tests such as the decomposition of isopropanol and the isomerization of 1-butene. The materials prepared show a good degree of crystallinity with a regular ordering of the pores into a hexagonal arrangement and high thermal stability. The specific surface area of the prepared materials decreases as the zirconium content rises. Zirconium atoms are in coordination 7 to 8 and located at the surface of the pores such that a high proportion of the oxygen atoms bonded to zirconium corresponds to surface non-condensed oxygen atoms. Both facts are responsible for the acid properties of the solids that show weak Brønsted and medium strong Lewis acidity.

  5. Radiation-induced silver agglomeration in molecular sieves: A comparison between A and X zeolites

    NASA Astrophysics Data System (ADS)

    Sadło, Jarosław; Waşowicz, Tomasz; Michalik, Jacek

    1995-06-01

    The stabilization conditions of silver atoms and clusters in hydrated and dehydrated AgNa-A and AgNa-X zeolites γ-irradiated at 77 K have been studied by ESR. It was found that silver agglomeration mechanisms in hydrated A and X zeolites are very similar and are controlled by the migration of silver atoms into the α-cages. In dehydrated zeolites agglomeration leads to completely different silver clusters in A and X zeolites. Small cationic clusters are stabilized in A zeolites and metallic clusters in X zeolites. Various factors affecting the agglomeration process in A and X zeolites are discussed.

  6. Synthesis and characterization of highly ordered Ni-MCM-41 mesoporous molecular sieves.

    PubMed

    Yang, Yanhui; Lim, Sangyun; Du, Guoan; Chen, Yuan; Ciuparu, Dragos; Haller, Gary L

    2005-07-14

    Highly ordered Ni-MCM-41 samples with nearly atomically dispersed nickel ions were prepared reproducibly and characterized. Similar to the Co-MCM-41 samples, the pore diameter and porosity can be precisely controlled by changing the synthesis surfactant chain length. Nickel was incorporated by isomorphous substitution of silicon in the MCM-41 silica framework, which makes the Ni-MCM-41 a physically stable catalyst in harsh reaction conditions such as CO disproportionation to single wall carbon nanotubes or CO2 methanation. X-ray absorption spectroscopy results indicate that the overall local environment of nickel in Ni-MCM-41 was a tetrahedral or distorted tetrahedral coordination with surrounding oxygen anions. Hydrogen TPR revealed that our Ni-MCM-41 samples have high stability against reduction; however, compared to Co-MCM-41, the Ni-MCM-41 has a lower reduction temperature, and both the H2-TPR and in situ XANES TPR reveal that the reducibility of nickel is not clearly correlated with the pore radius of curvature, as in the case of Co-MCM-41. This is probably a result of nickel being thermodynamically more easily reduced than cobalt. The stability of the structural order of Ni-MCM-41 has been investigated under SWNT synthesis and CO2 methanation reaction conditions as both require catalyst exposure to reducing environments leading to formation of metallic Ni clusters. Nitrogen physisorption and XRD results show that structural order was maintained under both SWNT synthesis and CO2 methanation reaction conditions. EXAFS results demonstrate that the nickel particle size can be controlled by different prereduction temperatures but not by the pore radius of curvature as in the case of Co-MCM-41. PMID:16852651

  7. Preparation, characterization, and catalytic performance of Ta-HMS mesoporous molecular sieve

    NASA Astrophysics Data System (ADS)

    Li, Xuefeng; Zhang, Like; Gao, Huanxin; Chen, Qingling

    2016-08-01

    Various Ta-HMS (hexagonal mesoporous silica) samples with different Ta content were hydrothermally prepared and characterized by XRD, N2-adsorption, ICP-AES, FTIR, and UV-Vis spectroscopy. The catalytic performance of the samples was also evaluated in the epoxidation of cyclohexene with cumene hydroperoxide as oxidant. The regularity of mesoporous structure decreases while more extraframe Ta ions are formed with increasing the Ta content. Ta-HMS with Ta/Si ratio of 0.015 shows the highest conversion and selectivity in the studied epoxidation reaction. The catalyst can be used for three times without significant activity loss.

  8. Optimization of Manganese Reduction in Biotreated POME onto 3A Molecular Sieve and Clinoptilolite Zeolites.

    PubMed

    Jami, Mohammed S; Rosli, Nurul-Shafiqah; Amosa, Mutiu K

    2016-06-01

    Availability of quality-certified water is pertinent to the production of food and pharmaceutical products. Adverse effects of manganese content of water on the corrosion of vessels and reactors necessitate that process water is scrutinized for allowable concentration levels before being applied in the production processes. In this research, optimization of the adsorption process conditions germane to the removal of manganese from biotreated palm oil mill effluent (BPOME) using zeolite 3A subsequent to a comparative adsorption with clinoptilolite was studied. A face-centered central composite design (FCCCD) of the response surface methodology (RSM) was adopted for the study. Analysis of variance (ANOVA) for response surface quadratic model revealed that the model was significant with dosage and agitation speed connoting the main significant process factors for the optimization. R(2) of 0.9478 yielded by the model was in agreement with predicted R(2). Langmuir and pseudo-second-order suggest the adsorption mechanism involved monolayer adsorption and cation exchanging. PMID:26556067

  9. Characterization of five subgroups of the sieve element occlusion gene family in Glycine max reveals genes encoding non-forisome P-proteins, forisomes and forisome tails.

    PubMed

    Zielonka, Sascia; Ernst, Antonia M; Hawat, Susan; Twyman, Richard M; Prüfer, Dirk; Noll, Gundula A

    2014-09-01

    P-proteins are structural phloem proteins discussed to be involved in the rapid sealing of injured sieve elements. P-proteins are found in all dicotyledonous and some monocotyledonous plants, but additional crystalloid P-proteins, known as forisomes, have evolved solely in the Fabaceae. Both types are encoded by members of the sieve element occlusion (SEO) gene family, which comprises seven phylogenetic subgroups. The Fabaceae-specific subgroup 1 contains genes encoding forisome subunits in e.g. Medicago truncatula, Vicia faba, Dipteryx panamensis and Canavalia gladiata whereas basal subgroup 5 encodes P-proteins in Nicotiana tabacum (tobacco) and Arabidopsis thaliana. The function of remaining subgroups is still unknown. We chose Glycine max (soybean) as a model to investigate SEO proteins representing different subgroups in one species. We isolated native P-proteins to determine the SEO protein composition and analyzed the expression pattern, localization and structure of the G. max SEO proteins representing five of the subgroups. We found that subgroup 1 GmSEO genes encode forisome subunits, a member of subgroup 5 encodes a non-forisome P-protein and subgroup 2 GmSEO genes encode the components of forisome tails, which are present in a restricted selection of Fabaceaen species. We therefore present the first molecular characterization of a Fabaceae non-forisome P-protein and the first evidence that forisome tails are encoded by a phylogenetically-distinct branch of the SEO gene family.

  10. OHMS**: Phytoplasmas dictate changes in sieve-element ultrastructure to accommodate their requirements for nutrition, multiplication and translocation

    PubMed Central

    Musetti, Rita; Pagliari, Laura; Buxa, Stefanie V.; Degola, Francesca; De Marco, Federica; Loschi, Alberto; Kogel, Karl-Heinz; van Bel, Aart J. E.

    2016-01-01

    ABSTRACT Phytoplasmas are among the most recently discovered plant pathogenic microorganisms so, many traits of the interactions with host plants and insect vectors are still unclear and need to be investigated. At now, it is impossible to determine the precise sequences leading to the onset of the relationship with the plant host cell. It is still unclear how phytoplasmas, located in the phloem sieve elements, exploit host cell to draw nutrition for their metabolism, growth and multiplication. In this work, basing on microscopical observations, we give insight about the structural interactions established by phytoplasmas and the sieve element plasma membrane, cytoskeleton, sieve endoplasmic reticulum, speculating about a possible functional role. PMID:26795235

  11. Wnt5a Signaling in Cancer

    PubMed Central

    Asem, Marwa S.; Buechler, Steven; Wates, Rebecca Burkhalter; Miller, Daniel L.; Stack, M. Sharon

    2016-01-01

    Wnt5a is involved in activating several non-canonical WNT signaling pathways, through binding to different members of the Frizzled- and Ror-family receptors. Wnt5a signaling is critical for regulating normal developmental processes, including proliferation, differentiation, migration, adhesion and polarity. However, the aberrant activation or inhibition of Wnt5a signaling is emerging as an important event in cancer progression, exerting both oncogenic and tumor suppressive effects. Recent studies show the involvement of Wnt5a in regulating cancer cell invasion, metastasis, metabolism and inflammation. In this article, we review findings regarding the molecular mechanisms and roles of Wnt5a signaling in various cancer types, and highlight Wnt5a in ovarian cancer. PMID:27571105

  12. Wnt5a Signaling in Cancer.

    PubMed

    Asem, Marwa S; Buechler, Steven; Wates, Rebecca Burkhalter; Miller, Daniel L; Stack, M Sharon

    2016-01-01

    Wnt5a is involved in activating several non-canonical WNT signaling pathways, through binding to different members of the Frizzled- and Ror-family receptors. Wnt5a signaling is critical for regulating normal developmental processes, including proliferation, differentiation, migration, adhesion and polarity. However, the aberrant activation or inhibition of Wnt5a signaling is emerging as an important event in cancer progression, exerting both oncogenic and tumor suppressive effects. Recent studies show the involvement of Wnt5a in regulating cancer cell invasion, metastasis, metabolism and inflammation. In this article, we review findings regarding the molecular mechanisms and roles of Wnt5a signaling in various cancer types, and highlight Wnt5a in ovarian cancer. PMID:27571105

  13. Sieve-based relation extraction of gene regulatory networks from biological literature

    PubMed Central

    2015-01-01

    Background Relation extraction is an essential procedure in literature mining. It focuses on extracting semantic relations between parts of text, called mentions. Biomedical literature includes an enormous amount of textual descriptions of biological entities, their interactions and results of related experiments. To extract them in an explicit, computer readable format, these relations were at first extracted manually from databases. Manual curation was later replaced with automatic or semi-automatic tools with natural language processing capabilities. The current challenge is the development of information extraction procedures that can directly infer more complex relational structures, such as gene regulatory networks. Results We develop a computational approach for extraction of gene regulatory networks from textual data. Our method is designed as a sieve-based system and uses linear-chain conditional random fields and rules for relation extraction. With this method we successfully extracted the sporulation gene regulation network in the bacterium Bacillus subtilis for the information extraction challenge at the BioNLP 2013 conference. To enable extraction of distant relations using first-order models, we transform the data into skip-mention sequences. We infer multiple models, each of which is able to extract different relationship types. Following the shared task, we conducted additional analysis using different system settings that resulted in reducing the reconstruction error of bacterial sporulation network from 0.73 to 0.68, measured as the slot error rate between the predicted and the reference network. We observe that all relation extraction sieves contribute to the predictive performance of the proposed approach. Also, features constructed by considering mention words and their prefixes and suffixes are the most important features for higher accuracy of extraction. Analysis of distances between different mention types in the text shows that our choice

  14. Porous aromatic frameworks with anion-templated pore apertures serving as polymeric sieves

    NASA Astrophysics Data System (ADS)

    Yuan, Ye; Sun, Fuxing; Li, Lina; Cui, Peng; Zhu, Guangshan

    2014-06-01

    Owing to environmental pollution and energy depletion, efficient separation of energy gases has attracted widespread attention. Low-cost and efficient adsorbents for gas separation are greatly needed. Here we report a family of quaternary pyridinium-type porous aromatic frameworks with tunable channels. After carefully choosing and adjusting the sterically hindered counter ions via a facile ion exchange approach, the pore diameters are tuned at an angstrom scale in the range of 3.4-7 Å. The designed pore sizes may bring benefits to capturing or sieving gas molecules with varied diameters to separate them efficiently by size-exclusive effects. By combining their specific separation properties, a five-component (hydrogen, nitrogen, oxygen, carbon dioxide and methane) gas mixture can be separated completely. The porous aromatic frameworks may hold promise for practical and commercial applications as polymeric sieves.

  15. Chip-based optical microscopy for imaging membrane sieve plates of liver scavenger cells

    NASA Astrophysics Data System (ADS)

    Helle, Øystein I.; Øie, Cristina I.; McCourt, Peter; Ahluwalia, Balpreet S.

    2015-08-01

    The evanescent field on top of optical waveguides is used to image membrane network and sieve-plates of liver endothelial cells. In waveguide excitation, the evanescent field is dominant only near the surface (~100-150 nm) providing a default optical sectioning by illuminating fluorophores in close proximity to the surface and thus benefiting higher signal-to-noise ratio. The sieve plates of liver sinusoidal endothelial cells are present on the cell membrane, thus near-field waveguide chip-based microscopy configuration is preferred over epi-fluorescence. The waveguide chip is compatible with optical fiber components allowing easy multiplexing to different wavelengths. In this paper, we will discuss the challenges and opportunities provided by integrated optical microscopy for imaging cell membranes.

  16. Reproducibility of a silicone-based test food to masticatory performance evaluation by different sieve methods.

    PubMed

    Sánchez-Ayala, Alfonso; Vilanova, Larissa Soares Reis; Costa, Marina Abrantes; Farias-Neto, Arcelino

    2014-01-01

    The aim of this study was to evaluate the reproducibility of the condensation silicone Optosil Comfort® as an artificial test food for masticatory performance evaluation. Twenty dentate subjects with mean age of 23.3±0.7 years were selected. Masticatory performance was evaluated using the simple (MPI), the double (IME) and the multiple sieve methods. Trials were carried out five times by three examiners: three times by the first, and once by the second and third examiners. Friedman's test was used to find the differences among time trials. Reproducibility was determined by the intra-class correlation (ICC) test (α=0.05). No differences among time trials were found, except for MPI-4 mm (p=0.022) from the first examiner results. The intra-examiner reproducibility (ICC) of almost all data was high (ICC≥0.92, p<0.001), being moderate only for MPI-0.50 mm (ICC=0.89, p<0.001). The inter-examiner reproducibility was high (ICC>0.93, p<0.001) for all results. For the multiple sieve method, the average mean of absolute difference from repeated measurements were lower than 1 mm. This trend was observed only from MPI-0.50 to MPI-1.4 for the single sieve method, and from IME-0.71/0.50 to IME-1.40/1.00 for the double sieve method. The results suggest that regardless of the method used, the reproducibility of Optosil Comfort® is high. PMID:24918363

  17. [Sieve-tube plastids of monocotyledons : Comparative investigations of the fine structure and distribution of specific plastids].

    PubMed

    Behnke, H D

    1968-06-01

    Fine-structural investigations of 24 monocotyledons from 21 families and all but one order succeeded in revealing a plastid with cuneate proteinaceous inclusion bodies as being typical of monocot sieve-tubes. Inclusion bodies originate in large numbers during plastid differentiation; they concentrate in the matrix and aggregate around an invisible centre, that mostly lies at one end of the elongated ameboid proplastid. The inclusion-free part of the young plastid contains countless vesicles and short membranes, presumably invaginations of the inner plastid envelope. Proteinaceous inclusion bodies show a crystal-like structure composed of 50-60 Å subunits in straight and parallel order. Besides these crystal-like inclusion bodies sieve-tube plastids of many monocotyledons also contain starch. - Sieve-tube plastids of Nuphar luteum and Nymphaea alba look like plastids in dicotyledon sieve-tubes, starch being their only inclusion.

  18. Chemical Reactivity of Formaldehyde in FeAlP0{sub 4} Sieve

    SciTech Connect

    Yeom, Young-Hoon; Ulagappan, Nagappan; Frei, Heinz

    2001-03-12

    Formaldehyde gas loaded into framework Fe aluminophosphate sieve (FeAlP O4-5) at 250 K was found to react with adsorbed H2O, CH3OH, H2O2, or lattice OH groups to yield the corresponding addition product, namely CH2(OH)2, CH3OCH2OH, HO 2CH2OH, or POCH2OH, respectively. Reactions were monitored in situ by static FT-IR spectroscopy, and assignments are based on experiments with CD2=0 and CD3OD. Most efficient was the reaction with H2O2 as indicated by the fact that HO2CH2OH was formed at the exclusion of CH2(OH)2 and POCH2OH when adsorbing formaldehyde onto a sieve loaded with H2O2 and H2O. Methoxymethanol, methanediol, and POCH2OH were stable at 250 K, but dissociated above 0 degrees C under release of formaldehyde. Hydromethyl hydroperoxide disproportionates to formic acid and water. Under 355 nm irradiation in FeAlPO4 sieve, HO2CH2OH was found to undergo efficient photofragmentation.

  19. Impact of fine mesh sieve primary treatment on nitrogen removal in moving bed biofilm reactors.

    PubMed

    Rusten, B; Razafimanantsoa, V A; Andriamiarinjaka, M A; Otis, C L; Sahu, A K; Bilstad, T

    2016-01-01

    The purpose of this project was to investigate the effect of selective particle removal during primary treatment on nitrogen removal in moving bed biofilm reactors (MBBRs). Two small MBBR pilot plants were operated in parallel, where one train treated 2 mm screened municipal wastewater and the other train treated wastewater that had passed through a Salsnes Filter SF1000 rotating belt sieve (RBS) with a 33 µs sieve cloth. The SF1000 was operated without a filter mat on the belt. The tests confirmed that, for the wastewater characteristics at the test plant, Salsnes Filter primary treatment with a 33 µs RBS and no filter mat produced a primary effluent that was close to optimum. Removal of organic matter with the 33 µs sieve had no negative effect on the denitrification process. Nitrification rates improved by 10-15% in the train with 33 µs RBS primary treatment. Mass balance calculations showed that without RBS primary treatment, the oxygen demand in the biological system was 36% higher. Other studies have shown that the sludge produced by RBS primary treatment is beneficial for biogas production and will also significantly improve sludge dewatering of the combined primary and biological sludge. PMID:26819389

  20. Highly Efficient Quantum Sieving in Porous Graphene-like Carbon Nitride for Light Isotopes Separation.

    PubMed

    Qu, Yuanyuan; Li, Feng; Zhou, Hongcai; Zhao, Mingwen

    2016-01-01

    Light isotopes separation, such as (3)He/(4)He, H2/D2, H2/T2, etc., is crucial for various advanced technologies including isotope labeling, nuclear weapons, cryogenics and power generation. However, their nearly identical chemical properties made the separation challenging. The low productivity of the present isotopes separation approaches hinders the relevant applications. An efficient membrane with high performance for isotopes separation is quite appealing. Based on first-principles calculations, we theoretically demonstrated that highly efficient light isotopes separation, such as (3)He/(4)He, can be reached in a porous graphene-like carbon nitride material via quantum sieving effect. Under moderate tensile strain, the quantum sieving of the carbon nitride membrane can be effectively tuned in a continuous way, leading to a temperature window with high (3)He/(4)He selectivity and permeance acceptable for efficient isotopes harvest in industrial application. This mechanism also holds for separation of other light isotopes, such as H2/D2, H2/T2. Such tunable quantum sieving opens a promising avenue for light isotopes separation for industrial application. PMID:26813491

  1. The angiosperm phloem sieve tube system: a role in mediating traits important to modern agriculture.

    PubMed

    Ham, Byung-Kook; Lucas, William J

    2014-04-01

    The plant vascular system serves a vital function by distributing water, nutrients and hormones essential for growth and development to the various organs of the plant. In this review, attention is focused on the role played by the phloem as the conduit for delivery of both photosynthate and information macromolecules, especially from the context of its mediation in traits that are important to modern agriculture. Resource allocation of sugars and amino acids, by the phloem, to specific sink tissues is of importance to crop yield and global food security. Current findings are discussed in the context of a hierarchical control network that operates to integrate resource allocation to competing sinks. The role of plasmodesmata that connect companion cells to neighbouring sieve elements and phloem parenchyma cells is evaluated in terms of their function as valves, connecting the sieve tube pressure manifold system to the various plant tissues. Recent studies have also revealed that plasmodesmata and the phloem sieve tube system function cooperatively to mediate the long-distance delivery of proteins and a diverse array of RNA species. Delivery of these information macromolecules is discussed in terms of their roles in control over the vegetative-to-floral transition, tuberization in potato, stress-related signalling involving miRNAs, and genetic reprogramming through the delivery of 24-nucleotide small RNAs that function in transcriptional gene silencing in recipient sink organs. Finally, we discuss important future research areas that could contribute to developing agricultural crops with engineered performance characteristics for enhance yield potential.

  2. Highly Efficient Quantum Sieving in Porous Graphene-like Carbon Nitride for Light Isotopes Separation

    PubMed Central

    Qu, Yuanyuan; Li, Feng; Zhou, Hongcai; Zhao, Mingwen

    2016-01-01

    Light isotopes separation, such as 3He/4He, H2/D2, H2/T2, etc., is crucial for various advanced technologies including isotope labeling, nuclear weapons, cryogenics and power generation. However, their nearly identical chemical properties made the separation challenging. The low productivity of the present isotopes separation approaches hinders the relevant applications. An efficient membrane with high performance for isotopes separation is quite appealing. Based on first-principles calculations, we theoretically demonstrated that highly efficient light isotopes separation, such as 3He/4He, can be reached in a porous graphene-like carbon nitride material via quantum sieving effect. Under moderate tensile strain, the quantum sieving of the carbon nitride membrane can be effectively tuned in a continuous way, leading to a temperature window with high 3He/4He selectivity and permeance acceptable for efficient isotopes harvest in industrial application. This mechanism also holds for separation of other light isotopes, such as H2/D2, H2/T2. Such tunable quantum sieving opens a promising avenue for light isotopes separation for industrial application. PMID:26813491

  3. Highly Efficient Quantum Sieving in Porous Graphene-like Carbon Nitride for Light Isotopes Separation

    NASA Astrophysics Data System (ADS)

    Qu, Yuanyuan; Li, Feng; Zhou, Hongcai; Zhao, Mingwen

    2016-01-01

    Light isotopes separation, such as 3He/4He, H2/D2, H2/T2, etc., is crucial for various advanced technologies including isotope labeling, nuclear weapons, cryogenics and power generation. However, their nearly identical chemical properties made the separation challenging. The low productivity of the present isotopes separation approaches hinders the relevant applications. An efficient membrane with high performance for isotopes separation is quite appealing. Based on first-principles calculations, we theoretically demonstrated that highly efficient light isotopes separation, such as 3He/4He, can be reached in a porous graphene-like carbon nitride material via quantum sieving effect. Under moderate tensile strain, the quantum sieving of the carbon nitride membrane can be effectively tuned in a continuous way, leading to a temperature window with high 3He/4He selectivity and permeance acceptable for efficient isotopes harvest in industrial application. This mechanism also holds for separation of other light isotopes, such as H2/D2, H2/T2. Such tunable quantum sieving opens a promising avenue for light isotopes separation for industrial application.

  4. Impact of fine mesh sieve primary treatment on nitrogen removal in moving bed biofilm reactors.

    PubMed

    Rusten, B; Razafimanantsoa, V A; Andriamiarinjaka, M A; Otis, C L; Sahu, A K; Bilstad, T

    2016-01-01

    The purpose of this project was to investigate the effect of selective particle removal during primary treatment on nitrogen removal in moving bed biofilm reactors (MBBRs). Two small MBBR pilot plants were operated in parallel, where one train treated 2 mm screened municipal wastewater and the other train treated wastewater that had passed through a Salsnes Filter SF1000 rotating belt sieve (RBS) with a 33 µs sieve cloth. The SF1000 was operated without a filter mat on the belt. The tests confirmed that, for the wastewater characteristics at the test plant, Salsnes Filter primary treatment with a 33 µs RBS and no filter mat produced a primary effluent that was close to optimum. Removal of organic matter with the 33 µs sieve had no negative effect on the denitrification process. Nitrification rates improved by 10-15% in the train with 33 µs RBS primary treatment. Mass balance calculations showed that without RBS primary treatment, the oxygen demand in the biological system was 36% higher. Other studies have shown that the sludge produced by RBS primary treatment is beneficial for biogas production and will also significantly improve sludge dewatering of the combined primary and biological sludge.

  5. In situ microscopy reveals reversible cell wall swelling in kelp sieve tubes: one mechanism for turgor generation and flow control?

    PubMed

    Knoblauch, Jan; Tepler Drobnitch, Sarah; Peters, Winfried S; Knoblauch, Michael

    2016-08-01

    Kelps, brown algae (Phaeophyceae) of the order Laminariales, possess sieve tubes for the symplasmic long-distance transport of photoassimilates that are evolutionarily unrelated but structurally similar to the tubes in the phloem of vascular plants. We visualized sieve tube structure and wound responses in fully functional, intact Bull Kelp (Nereocystis luetkeana [K. Mertens] Postels & Ruprecht 1840). In injured tubes, apparent slime plugs formed but were unlikely to cause sieve tube occlusion as they assembled at the downstream side of sieve plates. Cell walls expanded massively in the radial direction, reducing the volume of the wounded sieve elements by up to 90%. Ultrastructural examination showed that a layer of the immediate cell wall characterized by circumferential cellulose fibrils was responsible for swelling and suggested that alginates, abundant gelatinous polymers of the cell wall matrix, were involved. Wall swelling was rapid, reversible and depended on intracellular pressure, as demonstrated by pressure-injection of silicon oil. Our results revive the concept of turgor generation and buffering by swelling cell walls, which had fallen into oblivion over the last century. Because sieve tube transport is pressure-driven and controlled physically by tube diameter, a regulatory role of wall swelling in photoassimilate distribution is implied in kelps.

  6. In situ microscopy reveals reversible cell wall swelling in kelp sieve tubes: one mechanism for turgor generation and flow control?

    PubMed

    Knoblauch, Jan; Tepler Drobnitch, Sarah; Peters, Winfried S; Knoblauch, Michael

    2016-08-01

    Kelps, brown algae (Phaeophyceae) of the order Laminariales, possess sieve tubes for the symplasmic long-distance transport of photoassimilates that are evolutionarily unrelated but structurally similar to the tubes in the phloem of vascular plants. We visualized sieve tube structure and wound responses in fully functional, intact Bull Kelp (Nereocystis luetkeana [K. Mertens] Postels & Ruprecht 1840). In injured tubes, apparent slime plugs formed but were unlikely to cause sieve tube occlusion as they assembled at the downstream side of sieve plates. Cell walls expanded massively in the radial direction, reducing the volume of the wounded sieve elements by up to 90%. Ultrastructural examination showed that a layer of the immediate cell wall characterized by circumferential cellulose fibrils was responsible for swelling and suggested that alginates, abundant gelatinous polymers of the cell wall matrix, were involved. Wall swelling was rapid, reversible and depended on intracellular pressure, as demonstrated by pressure-injection of silicon oil. Our results revive the concept of turgor generation and buffering by swelling cell walls, which had fallen into oblivion over the last century. Because sieve tube transport is pressure-driven and controlled physically by tube diameter, a regulatory role of wall swelling in photoassimilate distribution is implied in kelps. PMID:26991892

  7. Quality Control of Trichinella Testing at the Slaughterhouse Laboratory: Evaluation of the Use of a 400-Micrometer-Mesh-Size Sieve in the Magnetic Stirrer Method.

    PubMed

    Franssen, Frits; van Andel, Esther; Swart, Arno; van der Giessen, Joke

    2016-02-01

    The performance of a 400-μm-mesh-size sieve (sieve400) has not previously been compared with that of a 180-μm-mesh-size sieve (sieve180). Using pork samples spiked with 0 to 10 Trichinella muscle larvae and an artificial digestion method, sieve performance was evaluated for control of Trichinella in meat-producing animals. The use of a sieve400 resulted in 12% lower larval counts, 147% more debris, and 28% longer counting times compared with the use of a sieve180. Although no false-negative results were obtained, prolonged counting times with the sieve400 may have an impact on performance in a high-throughput environment such as a slaughterhouse laboratory. Based on our results, the sieve180 remains the sieve of choice for Trichinella control in meat in slaughterhouse laboratories, according to the European Union reference method (European Commission regulation 2075/2005). Furthermore, the results of the present study contribute to the discussion of harmonization of meat inspection requirements among countries. PMID:26818995

  8. Quality Control of Trichinella Testing at the Slaughterhouse Laboratory: Evaluation of the Use of a 400-Micrometer-Mesh-Size Sieve in the Magnetic Stirrer Method.

    PubMed

    Franssen, Frits; van Andel, Esther; Swart, Arno; van der Giessen, Joke

    2016-02-01

    The performance of a 400-μm-mesh-size sieve (sieve400) has not previously been compared with that of a 180-μm-mesh-size sieve (sieve180). Using pork samples spiked with 0 to 10 Trichinella muscle larvae and an artificial digestion method, sieve performance was evaluated for control of Trichinella in meat-producing animals. The use of a sieve400 resulted in 12% lower larval counts, 147% more debris, and 28% longer counting times compared with the use of a sieve180. Although no false-negative results were obtained, prolonged counting times with the sieve400 may have an impact on performance in a high-throughput environment such as a slaughterhouse laboratory. Based on our results, the sieve180 remains the sieve of choice for Trichinella control in meat in slaughterhouse laboratories, according to the European Union reference method (European Commission regulation 2075/2005). Furthermore, the results of the present study contribute to the discussion of harmonization of meat inspection requirements among countries.

  9. Preliminary Evaluation of Cesium Distribution for Wet Sieving Process Planned for Soil Decontamination in Japan - 13104

    SciTech Connect

    Enokida, Y.; Tanada, Y.; Hirabayashi, D.; Sawada, K.

    2013-07-01

    For the purpose of decontaminating radioactive cesium from a huge amount of soil, which has been estimated to be 1.2x10{sup 8} m{sup 3} by excavating to a 5-cm depth from the surface of Fukushima Prefecture where a severe nuclear accident occurred at TEPCO's power generating site and has emitted a significant amount of radioactive materials, mainly radioactive cesium, a wet sieving process was selected as one of effective methods available in Japan. Some private companies have demonstrated this process for soil treatment in the Fukushima area by testing at their plants. The results were very promising, and a full-fledged application is expected to follow. In the present study, we spiked several aqueous samples containing soil collected from an industrial wet sieving plant located near our university for the recycling of construction wastes with non-radioactive cesium hydroxide. The present study provides scientific data concerning the effectiveness in volume reduction of the contaminated soil by a wet sieving process as well as the cesium distribution between the liquid phase and clay minerals for each sub-process of the full-scale one, but a simulating plant equipped with a process of coagulating sedimentation and operational safety fundamentals for the plant. Especially for the latter aspect, the study showed that clay minerals of submicron size strongly bind a high content of cesium, which was only slightly removed by coagulation with natural sedimentation (1 G) nor centrifugal sedimentation (3,700 G) and some of the cesium may be transferred to the effluent or recycled water. By applying ultracentrifugation (257,000 G), most of submicron clay minerals containing cesium was removed, and the cesium amount which might be transferred to the effluent or recycled water, could be reduced to less than 2.3 % of the original design by the addition of a cesium barrier consisting of ultracentrifugation or a hollow fiber membrane. (authors)

  10. GFP Tagging of Sieve Element Occlusion (SEO) Proteins Results in Green Fluorescent Forisomes

    PubMed Central

    Pélissier, Hélène C.; Peters, Winfried S.; Collier, Ray; van Bel, Aart J. E.; Knoblauch, Michael

    2008-01-01

    Forisomes are Ca2+-driven, ATP-independent contractile protein bodies that reversibly occlude sieve elements in faboid legumes. They apparently consist of at least three proteins; potential candidates have been described previously as ‘FOR’ proteins. We isolated three genes from Medicago truncatula that correspond to the putative forisome proteins and expressed their green fluorescent protein (GFP) fusion products in Vicia faba and Glycine max using the composite plant methodology. In both species, expression of any of the constructs resulted in homogenously fluorescent forisomes that formed sieve tube plugs upon stimulation; no GFP fluorescence occurred elsewhere. Isolated fluorescent forisomes reacted to Ca2+ and chelators by contraction and expansion, respectively, and did not lose fluorescence in the process. Wild-type forisomes showed no affinity for free GFP in vitro. The three proteins shared numerous conserved motifs between themselves and with hypothetical proteins derived from the genomes of M. truncatula, Vitis vinifera and Arabidopsis thaliana. However, they showed neither significant similarities to proteins of known function nor canonical metal-binding motifs. We conclude that ‘FOR’-like proteins are components of forisomes that are encoded by a well-defined gene family with relatives in taxa that lack forisomes. Since the mnemonic FOR is already registered and in use for unrelated genes, we suggest the acronym SEO (sieve element occlusion) for this family. The absence of binding sites for divalent cations suggests that the Ca2+ binding responsible for forisome contraction is achieved either by as yet unidentified additional proteins, or by SEO proteins through a novel, uncharacterized mechanism. PMID:18784195

  11. Sieve tray performances for steam stripping toluene from water in a 4-ft diameter column

    SciTech Connect

    Kunesh, J.G.; Ognisty, T.P.; Sakata, M.; Chen, G.X.

    1996-08-01

    The liquid holdup, pressure drop, and mass transfer efficiency of sieve trays for the steam stripping trace toluene from water were measured from a 4-ft column at atmospheric pressure. The measured data were then compared with predictions from often-used models. It was found that the published efficiency models whether based on distillation or stripping systems are unable to predict both the trend and value of the measured efficiency. Since the 4-ft column owned by Fractionation Research, Inc. (FRI) can be considered as an industrial-scale column, the measured efficiency provides immediate design guidelines for such services.

  12. Phytoplasma infection in tomato is associated with re-organization of plasma membrane, ER stacks, and actin filaments in sieve elements

    PubMed Central

    Buxa, Stefanie V.; Degola, Francesca; Polizzotto, Rachele; De Marco, Federica; Loschi, Alberto; Kogel, Karl-Heinz; di Toppi, Luigi Sanità; van Bel, Aart J. E.; Musetti, Rita

    2015-01-01

    Phytoplasmas, biotrophic wall-less prokaryotes, only reside in sieve elements of their host plants. The essentials of the intimate interaction between phytoplasmas and their hosts are poorly understood, which calls for research on potential ultrastructural modifications. We investigated modifications of the sieve-element ultrastructure induced in tomato plants by ‘Candidatus Phytoplasma solani,’ the pathogen associated with the stolbur disease. Phytoplasma infection induces a drastic re-organization of sieve-element substructures including changes in plasma membrane surface and distortion of the sieve-element reticulum. Observations of healthy and stolbur-diseased plants provided evidence for the emergence of structural links between sieve-element plasma membrane and phytoplasmas. One-sided actin aggregates on the phytoplasma surface also inferred a connection between phytoplasma and sieve-element cytoskeleton. Actin filaments displaced from the sieve-element mictoplasm to the surface of the phytoplasmas in infected sieve elements. Western blot analysis revealed a decrease of actin and an increase of ER-resident chaperone luminal binding protein (BiP) in midribs of phytoplasma-infected plants. Collectively, the studies provided novel insights into ultrastructural responses of host sieve elements to phloem-restricted prokaryotes. PMID:26347766

  13. Method for Determining the Activation Energy Distribution Function of Complex Reactions by Sieving and Thermogravimetric Measurements.

    PubMed

    Bufalo, Gennaro; Ambrosone, Luigi

    2016-01-14

    A method for studying the kinetics of thermal degradation of complex compounds is suggested. Although the method is applicable to any matrix whose grain size can be measured, herein we focus our investigation on thermogravimetric analysis, under a nitrogen atmosphere, of ground soft wheat and ground maize. The thermogravimetric curves reveal that there are two well-distinct jumps of mass loss. They correspond to volatilization, which is in the temperature range 298-433 K, and decomposition regions go from 450 to 1073 K. Thermal degradation is schematized as a reaction in the solid state whose kinetics is analyzed separately in each of the two regions. By means of a sieving analysis different size fractions of the material are separated and studied. A quasi-Newton fitting algorithm is used to obtain the grain size distribution as best fit to experimental data. The individual fractions are thermogravimetrically analyzed for deriving the functional relationship between activation energy of the degradation reactions and the particle size. Such functional relationship turns out to be crucial to evaluate the moments of the activation energy distribution, which is unknown in terms of the distribution calculated by sieve analysis. From the knowledge of moments one can reconstruct the reaction conversion. The method is applied first to the volatilization region, then to the decomposition region. The comparison with the experimental data reveals that the method reproduces the experimental conversion with an accuracy of 5-10% in the volatilization region and of 3-5% in the decomposition region.

  14. Combining sieving and washing, a way to treat MSWI boiler fly ash.

    PubMed

    De Boom, Aurore; Degrez, Marc

    2015-05-01

    Municipal Solid Waste Incineration (MSWI) fly ashes contain some compounds that could be extracted and valorised. A process based on wet sieving and washing steps has been developed aiming to reach this objective. Such unique combination in MSWI fly ash treatment led to a non-hazardous fraction from incineration fly ashes. More specifically, MSWI Boiler Fly Ash (BFA) was separately sampled and treated. The BFA finer particles (13wt%) were found to be more contaminated in Pb and Zn than the coarser fractions. After three washing steps, the coarser fractions presented leaching concentrations acceptable to landfill for non-hazardous materials so that an eventual subsequent valorisation may be foreseen. At the contrary, too much Pb leached from the finest particles and this fraction should be further treated. Wet sieving and washing permit thus to reduce the leachability of MSWI BFA and to concentrate the Pb and Zn contamination in a small (in particle size and volume) fraction. Such combination would therefore constitute a straightforward and efficient basis to valorise coarse particles from MSWI fly ashes. PMID:25736808

  15. Remembering the SIEV X: who cares for the bodies of the stateless, lost at sea?

    PubMed

    Gibbings, Beth

    2010-02-01

    The SIEV X was a tiny fishing vessel traveling from Indonesia to Australia in 2001, carrying around four hundred people seeking asylum after fleeing from the warfare and persecution predominantly in Iraq and Afghanistan. Many were women and children trying to enter Australia to join fathers and husbands already granted refugee status but not allowed to bring in family members because of new Australian laws on "Temporary Protection Visas". Of these, 353 drowned when the boat sank in international waters. The conservative Australian government denied responsibility, using the event in an election campaign to play on fears about illegal entry and border defense in the Islamophobic climate in the aftermath of 9/11. Yet many everyday Australians eventually became involved in a collaborative design process to create a memorial to those asylum seekers. This article discusses the debates around memorials for those lost at sea, and particularly for those who might be portrayed as enemies or "illegal immigrants" whose coming threatens national borders. It identifies the conditions under which the campaign to commemorate those who died on the SIEV X moved from being a minority interest to become a cause so widely supported by Australians across the country that the memorial was eventually erected in the heart of the national capital. PMID:20503912

  16. Involvement of the sieve element cytoskeleton in electrical responses to cold shocks.

    PubMed

    Hafke, Jens B; Ehlers, Katrin; Föller, Jens; Höll, Sabina-Roxana; Becker, Stefanie; van Bel, Aart J E

    2013-06-01

    This study dealt with the visualization of the sieve element (SE) cytoskeleton and its involvement in electrical responses to local cold shocks, exemplifying the role of the cytoskeleton in Ca(2+)-triggered signal cascades in SEs. High-affinity fluorescent phalloidin as well as immunocytochemistry using anti-actin antibodies demonstrated a fully developed parietal actin meshwork in SEs. The involvement of the cytoskeleton in electrical responses and forisome conformation changes as indicators of Ca(2+) influx was investigated by the application of cold shocks in the presence of diverse actin disruptors (latrunculin A and cytochalasin D). Under control conditions, cold shocks elicited a graded initial voltage transient, ΔV1, reduced by external La(3+) in keeping with the involvement of Ca(2+) channels, and a second voltage transient, ΔV2. Cytochalasin D had no effect on ΔV1, while ΔV1 was significantly reduced with 500 nm latrunculin A. Forisome dispersion was triggered by cold shocks of 4°C or greater, which was indicative of an all-or-none behavior. Forisome dispersion was suppressed by incubation with latrunculin A. In conclusion, the cytoskeleton controls cold shock-induced Ca(2+) influx into SEs, leading to forisome dispersion and sieve plate occlusion in fava bean (Vicia faba).

  17. Morphine biosynthesis in opium poppy involves two cell types: sieve elements and laticifers.

    PubMed

    Onoyovwe, Akpevwe; Hagel, Jillian M; Chen, Xue; Khan, Morgan F; Schriemer, David C; Facchini, Peter J

    2013-10-01

    Immunofluorescence labeling and shotgun proteomics were used to establish the cell type-specific localization of morphine biosynthesis in opium poppy (Papaver somniferum). Polyclonal antibodies for each of six enzymes involved in converting (R)-reticuline to morphine detected corresponding antigens in sieve elements of the phloem, as described previously for all upstream enzymes transforming (S)-norcoclaurine to (S)-reticuline. Validated shotgun proteomics performed on whole-stem and latex total protein extracts generated 2031 and 830 distinct protein families, respectively. Proteins corresponding to nine morphine biosynthetic enzymes were represented in the whole stem, whereas only four of the final five pathway enzymes were detected in the latex. Salutaridine synthase was detected in the whole stem, but not in the latex subproteome. The final three enzymes converting thebaine to morphine were among the most abundant active latex proteins despite a limited occurrence in laticifers suggested by immunofluorescence labeling. Multiple charge isoforms of two key O-demethylases in the latex were revealed by two-dimensional immunoblot analysis. Salutaridine biosynthesis appears to occur only in sieve elements, whereas conversion of thebaine to morphine is predominant in adjacent laticifers, which contain morphine-rich latex. Complementary use of immunofluorescence labeling and shotgun proteomics has substantially resolved the cellular localization of morphine biosynthesis in opium poppy.

  18. Combining sieving and washing, a way to treat MSWI boiler fly ash.

    PubMed

    De Boom, Aurore; Degrez, Marc

    2015-05-01

    Municipal Solid Waste Incineration (MSWI) fly ashes contain some compounds that could be extracted and valorised. A process based on wet sieving and washing steps has been developed aiming to reach this objective. Such unique combination in MSWI fly ash treatment led to a non-hazardous fraction from incineration fly ashes. More specifically, MSWI Boiler Fly Ash (BFA) was separately sampled and treated. The BFA finer particles (13wt%) were found to be more contaminated in Pb and Zn than the coarser fractions. After three washing steps, the coarser fractions presented leaching concentrations acceptable to landfill for non-hazardous materials so that an eventual subsequent valorisation may be foreseen. At the contrary, too much Pb leached from the finest particles and this fraction should be further treated. Wet sieving and washing permit thus to reduce the leachability of MSWI BFA and to concentrate the Pb and Zn contamination in a small (in particle size and volume) fraction. Such combination would therefore constitute a straightforward and efficient basis to valorise coarse particles from MSWI fly ashes.

  19. Involvement of the sieve element cytoskeleton in electrical responses to cold shocks.

    PubMed

    Hafke, Jens B; Ehlers, Katrin; Föller, Jens; Höll, Sabina-Roxana; Becker, Stefanie; van Bel, Aart J E

    2013-06-01

    This study dealt with the visualization of the sieve element (SE) cytoskeleton and its involvement in electrical responses to local cold shocks, exemplifying the role of the cytoskeleton in Ca(2+)-triggered signal cascades in SEs. High-affinity fluorescent phalloidin as well as immunocytochemistry using anti-actin antibodies demonstrated a fully developed parietal actin meshwork in SEs. The involvement of the cytoskeleton in electrical responses and forisome conformation changes as indicators of Ca(2+) influx was investigated by the application of cold shocks in the presence of diverse actin disruptors (latrunculin A and cytochalasin D). Under control conditions, cold shocks elicited a graded initial voltage transient, ΔV1, reduced by external La(3+) in keeping with the involvement of Ca(2+) channels, and a second voltage transient, ΔV2. Cytochalasin D had no effect on ΔV1, while ΔV1 was significantly reduced with 500 nm latrunculin A. Forisome dispersion was triggered by cold shocks of 4°C or greater, which was indicative of an all-or-none behavior. Forisome dispersion was suppressed by incubation with latrunculin A. In conclusion, the cytoskeleton controls cold shock-induced Ca(2+) influx into SEs, leading to forisome dispersion and sieve plate occlusion in fava bean (Vicia faba). PMID:23624858

  20. Involvement of the Sieve Element Cytoskeleton in Electrical Responses to Cold Shocks1[W

    PubMed Central

    Hafke, Jens B.; Ehlers, Katrin; Föller, Jens; Höll, Sabina-Roxana; Becker, Stefanie; van Bel, Aart J.E.

    2013-01-01

    This study dealt with the visualization of the sieve element (SE) cytoskeleton and its involvement in electrical responses to local cold shocks, exemplifying the role of the cytoskeleton in Ca2+-triggered signal cascades in SEs. High-affinity fluorescent phalloidin as well as immunocytochemistry using anti-actin antibodies demonstrated a fully developed parietal actin meshwork in SEs. The involvement of the cytoskeleton in electrical responses and forisome conformation changes as indicators of Ca2+ influx was investigated by the application of cold shocks in the presence of diverse actin disruptors (latrunculin A and cytochalasin D). Under control conditions, cold shocks elicited a graded initial voltage transient, ΔV1, reduced by external La3+ in keeping with the involvement of Ca2+ channels, and a second voltage transient, ΔV2. Cytochalasin D had no effect on ΔV1, while ΔV1 was significantly reduced with 500 nm latrunculin A. Forisome dispersion was triggered by cold shocks of 4°C or greater, which was indicative of an all-or-none behavior. Forisome dispersion was suppressed by incubation with latrunculin A. In conclusion, the cytoskeleton controls cold shock-induced Ca2+ influx into SEs, leading to forisome dispersion and sieve plate occlusion in fava bean (Vicia faba). PMID:23624858

  1. Remembering the SIEV X: who cares for the bodies of the stateless, lost at sea?

    PubMed

    Gibbings, Beth

    2010-02-01

    The SIEV X was a tiny fishing vessel traveling from Indonesia to Australia in 2001, carrying around four hundred people seeking asylum after fleeing from the warfare and persecution predominantly in Iraq and Afghanistan. Many were women and children trying to enter Australia to join fathers and husbands already granted refugee status but not allowed to bring in family members because of new Australian laws on "Temporary Protection Visas". Of these, 353 drowned when the boat sank in international waters. The conservative Australian government denied responsibility, using the event in an election campaign to play on fears about illegal entry and border defense in the Islamophobic climate in the aftermath of 9/11. Yet many everyday Australians eventually became involved in a collaborative design process to create a memorial to those asylum seekers. This article discusses the debates around memorials for those lost at sea, and particularly for those who might be portrayed as enemies or "illegal immigrants" whose coming threatens national borders. It identifies the conditions under which the campaign to commemorate those who died on the SIEV X moved from being a minority interest to become a cause so widely supported by Australians across the country that the memorial was eventually erected in the heart of the national capital.

  2. Slower phloem transport in gymnosperm trees can be attributed to higher sieve element resistance.

    PubMed

    Liesche, Johannes; Windt, Carel; Bohr, Tomas; Schulz, Alexander; Jensen, Kaare H

    2015-04-01

    In trees, carbohydrates produced in photosynthesizing leaves are transported to roots and other sink organs over distances of up to 100 m inside a specialized transport tissue, the phloem. Angiosperm and gymnosperm trees have a fundamentally different phloem anatomy with respect to cell size, shape and connectivity. Whether these differences have an effect on the physiology of carbohydrate transport, however, is not clear. A meta-analysis of the experimental data on phloem transport speed in trees yielded average speeds of 56 cm h(-1) for angiosperm trees and 22 cm h(-1) for gymnosperm trees. Similar values resulted from theoretical modeling using a simple transport resistance model. Analysis of the model parameters clearly identified sieve element (SE) anatomy as the main factor for the significantly slower carbohydrate transport speed inside the phloem in gymnosperm compared with angiosperm trees. In order to investigate the influence of SE anatomy on the hydraulic resistance, anatomical data on SEs and sieve pores were collected by transmission electron microscopy analysis and from the literature for 18 tree species. Calculations showed that the hydraulic resistance is significantly higher in the gymnosperm than in angiosperm trees. The higher resistance is only partially offset by the considerably longer SEs of gymnosperms.

  3. Molecular dynamics computer simulation of permeation in solids

    SciTech Connect

    Pohl, P.I.; Heffelfinger, G.S.; Fisler, D.K.; Ford, D.M.

    1997-12-31

    In this work the authors simulate permeation of gases and cations in solid models using molecular mechanics and a dual control volume grand canonical molecular dynamics technique. The molecular sieving nature of microporous zeolites are discussed and compared with that for amorphous silica made by sol-gel methods. One mesoporous and one microporous membrane model are tested with Lennard-Jones gases corresponding to He, H{sub 2}, Ar and CH{sub 4}. The mesoporous membrane model clearly follows a Knudsen diffusion mechanism, while the microporous model having a hard-sphere cutoff pore diameter of {approximately}3.4 {angstrom} demonstrates molecular sieving of the methane ({sigma} = 3.8 {angstrom}) but anomalous behavior for Ar ({sigma} = 3.4 {angstrom}). Preliminary results of Ca{sup +} diffusion in calcite and He/H{sub 2} diffusion in polyisobutylene are also presented.

  4. Ultrafiltration Failure and Impaired Sodium Sieving During Long-Term Peritoneal Dialysis: More Than Aquaporin Dysfunction?

    PubMed

    Morelle, Johann; Sow, Amadou; Hautem, Nicolas; Devuyst, Olivier; Goffin, Eric

    2016-01-01

    Fifteen years ago, our group reported the case of a 67-year-old man on peritoneal dialysis for 11 years, in whom ultrafiltration failure and impaired sodium sieving were associated with an apparently normal expression of aquaporin-1 (AQP1) water channels in peritoneal capillaries. At that time, AQP1 dysfunction was suggested as the cause of impaired free-water transport. However, recent data from computer simulations, and structural and functional analysis of the peritoneal membrane of patients with encapsulating peritoneal sclerosis, demonstrated that changes in the peritoneal interstitium directly alter osmotic water transport. In light of these insights, we challenge the initial hypothesis and provide several lines of evidence supporting the diagnosis of encapsulating peritoneal sclerosis in this patient and suggesting that severe peritoneal fibrosis accounted for the loss of osmotic conductance developed during the course of peritoneal dialysis. PMID:27006441

  5. Symplastic isolation of the sieve element-companion cell complex in the phloem of Ricinus communis and Salix alba stems.

    PubMed

    van Bel, A J; Kempers, R

    1991-12-01

    The anatomical and physiological isolation of the sieve element-companion cell complex (se-cc complex) was investigated in stems of Ricinus communis L. and Salix alba L. In Ricinus, the plasmodesmatal frequencies were in the proportions 8∶1∶2∶30, in the order given, at the interfaces between sieve tube-companion cell, sieve tube-phloem parenchyma cell, companion cellphloem parenchyma cell, and phloem parenchyma cellphloem parenchyma cell. The membrane potentials of the se-cc complex and the surrounding phloem-parenchyma cells sharply contrasted: the membrane potential of the se-cc complex was about twice as negative as that of the phloem parenchyma. Lucifer Yellow CH injected into the sieve element or into the companion cell remained within the se-cc complex. Dye introduced into phloem parenchyma only moved (mostly poorly) to other phloem-parenchyma cells. The distribution of the plasmodesmatal frequencies, the differential dye-coupling and the sharp discontinuities in membrane potentials indicate that the se-cc complexes constitute symplast domains in the stem phloem. Symplastic autonomy is discussed as a basic necessity for the functioning of the se-cc complex in the stem.

  6. Improving the accuracy of sediment-associated constituent concentrations in whole storm water samples by wet-sieving

    USGS Publications Warehouse

    Selbig, W.R.; Bannerman, R.; Bowman, G.

    2007-01-01

    Sand-sized particles (>63 ??m) in whole storm water samples collected from urban runoff have the potential to produce data with substantial bias and/or poor precision both during sample splitting and laboratory analysis. New techniques were evaluated in an effort to overcome some of the limitations associated with sample splitting and analyzing whole storm water samples containing sand-sized particles. Wet-sieving separates sand-sized particles from a whole storm water sample. Once separated, both the sieved solids and the remaining aqueous (water suspension of particles less than 63 ??m) samples were analyzed for total recoverable metals using a modification of USEPA Method 200.7. The modified version digests the entire sample, rather than an aliquot, of the sample. Using a total recoverable acid digestion on the entire contents of the sieved solid and aqueous samples improved the accuracy of the derived sediment-associated constituent concentrations. Concentration values of sieved solid and aqueous samples can later be summed to determine an event mean concentration. ?? ASA, CSSA, SSSA.

  7. Compact sieve-tray distillation column for ammonia-water absorption heat pump: Part 1 -- Design methodology

    SciTech Connect

    Anand, G.; Erickson, D.C.

    1999-07-01

    The distillation column is a key component of ammonia-water absorption units including advanced generator-absorber heat exchange (GAX) cycle heat pumps. The design of the distillation column is critical to unit performance, size, and cost. The distillation column can be designed with random packing, structured packing, or various tray configurations. A sieve-tray distillation column is the least complicated tray design and is less costly than high-efficiency packing. Substantial literature is available on sieve tray design and performance. However, most of the correlations and design recommendations were developed for large industrial hydrocarbon systems and are generally not directly applicable to the compact ammonia-water column discussed here. The correlations were reviewed and modified as appropriate for this application, and a sieve-tray design model was developed. This paper presents the sieve-tray design methodology for highly compact ammonia-water columns. A conceptual design of the distillation column for an 8 ton vapor exchange (VX) GAX heat pump is presented, illustrating relevant design parameters and trends. The design process revealed several issues that have to be investigated experimentally to design the final optimized rectifier. Validation of flooding and weeping limits and tray/point efficiencies are of primary importance.

  8. Tocopherols and tocotrienols in barley oil prepared from germ and other fractions from scarification and sieving of hulless barley

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Two cultivars of hulless barley (Doyce and Merlin), were scarified to abrade the outer layers of the kernels (germ, pericarp, and aleurone). The resulting scarification fines fractions were then separated into four particle size subfractions using sieves. Each of the size subfractions was then extr...

  9. Ground, sieved, and C18 modified monolithic silica particles for packing material of microcolumn high-performance liquid chromatography.

    PubMed

    Ko, Joung Ho; Baik, Yoon Suk; Park, Seong Tae; Cheong, Won Jo

    2007-03-16

    We here report a new type of stationary phase for microcolumns. C18 modified silica monolith particles were prepared by grinding and sieving the silica monolith followed by C18 modification and end-capping, and were used as packing material. Ground silica monolith particles were not spherical but irregular with some residual monolithic network structure. The separation efficiency of the stationary phase made of sieved monolith particles (5-10 microm) was better than that of the stationary phase made of unsieved particles. The microcolumn packed with the sieved C18 ground monolith particles (5-10 microm) showed quite good separation efficiency (height equivalent to theoretical plate, HETP, as low as 15 microm) and it was even superior to the microcolumn packed with a commercial spherical 5 microm C18 stationary phase. The column pressure drop of C18 monolith particles was about two-third of that of the commercial spherical C18 phase. The preparation method of C18 stationary phase with ground and sieved silica monolith particles presumably suggests advantages of simplicity and convenience in modification and washing procedures compared to bulk silica monolith. It also showed both improved separation efficiency and low back pressure. PMID:17289065

  10. Recovery of macroinvertebrates by screening in the field: a comparison between coarse (1.18 mm) and fine (0.60 mm) mesh sieves

    USGS Publications Warehouse

    Dukerschein, J.T.; Gent, R.; Sauer, J.

    1996-01-01

    We evaluated the potential loss of target benthic macroinvertebrates from coarse-mesh field wash down of samples through a 1.18-mm mesh sieve nested on a 0.60-mm mesh sieve. Visible target organisms (midges, mayflies, and fingernail clams) in the 1.18-mm mesh sieve were removed from the sample and enumerated in the field. The entire contents of both sieves were preserved for subsequent laboratory enumeration under 4X magnification. Percent recoveries from each treatment were based on total intact organisms found in all sieves. Percent recovery for fingernail clams found in the field (31%) was lower than for mayflies (79%) and midges (88%). Laboratory enumeration of organisms retained by the 1.18-mm sieve yielded additional fingernail clams (to total 74% recovered in the field and lab), mayflies (to total 89%), and midges (to total 91%). If the 1.18-mm sieve is used alone in the field, it is adequate to monitor mayflies, midges >1 cm, and adult fingernail clams greater than or equal to 5.0 mm shell length.

  11. Sieve textures in impact zircon from Vredefort, South Africa: Implications to impact geochronology

    NASA Astrophysics Data System (ADS)

    Wielicki, M. M.; Harrison, M.

    2013-12-01

    The bombardment history of our planet has major implications for Earth's atmosphere, habitability, near surface conditions, and the delivery of the building blocks of life over its four and a half billion years. Constraining the impact flux was highlighted by the National Research Council's 2007 report "The Scientific Context for the Exploration of the Moon" as the top priority goal for lunar research as evidence of such a bombardment is uniquely preserved on the lunar surface. Evidence of the impact flux on the Earth-Moon system has largely been based on interpretations of Ar-Ar ages of lunar samples which can be problematic due to the presence of relic clasts, incomplete Ar outgassing, diffusive modification during shock and heating, and exposure to solar wind and cosmic rays. Recent studies have utilized zircon from Apollo samples as well as lunar meteorites to better constrain the impact history of the Moon. Sieve textures found in zircon within lunar meteorite SaU 169 have been identified as "poikilitic impact melt zircon formed during equilibrium crystallization of the impact melt" and used to better constrain the age of the Imbrium impact. Such textures had previously not been observed in terrestrial zircon. We report the first terrestrial sieve textures in zircon isolated from Vredefort impactites. Zircons isolated from the granophyre unit show a intimate relationship with pyroxene, similar to that seen in the lunar samples. U-Pb analysis of such grains clearly shows that the zircons have been inherited from the target and are not neo-formed zircon that crystallized from the impact melt and thus should not be used to imply impact events. Pb-loss is highly variable in these samples and the lower intercept age of ~1985×150 Ma agrees well with that of the Vredefort impact. Such textures have been previously observed in plagioclase from rapid decompression and resorption into non-equilibrium melts and do not represent primary growth features. Zircon

  12. Molecular modification of proanthocyanidins.

    PubMed

    Huo, Qing; Kong, Xiangye; Yang, Xiaofang; Wang, Yue; Ma, Lingling; Luo, Min; Xu, Diandou

    2016-07-01

    Regioselective enzymatic acylation of proanthocyanidin is proposed and investigated as a method by which to improve the solubility of proanthocyanidins in the oil phase and maintain its oxidation resistance. Experimental results indicate that butanol functions as the best solvent in the studied reaction, in which Lipase Novozym435 is used as biological catalyst enzyme and the molar ratio of lauric acid to proanthocyanidins is 4:1. To increase the esterification conversion, we propose the addition of molecular sieve at 5 h. The product was separated by TLC, and results indicate an optimal solvent ratio of ethyl acetate: petroleum ether: acetic acid = 2:3:0.5. This condition can effectively separate the ester and proanthocyanidins, achieving an esterification yield of 60.9%. PMID:27459598

  13. Coulombic dragging of molecular assemblies on nanotubes

    NASA Astrophysics Data System (ADS)

    Kral, Petr; Sint, Kyaw; Wang, Boyang

    2009-03-01

    We show by molecular dynamics simulations that polar molecules, ions and their assemblies could be Coulombically dragged on the surfaces of single-wall carbon and boron-nitride nanotubes by ionic solutions or individual ions moving inside the nanotubes [1,2]. We also briefly discuss highly selective ionic sieves based on graphene monolayers with nanopores [3]. These phenomena could be applied in molecular delivery, separation and desalination.[3pt] [1] Boyang Wang and Petr Kral, JACS 128, 15984 (2006). [0pt] [2] Boyang Wang and Petr Kral, Phys. Rev. Lett. 101, 046103 (2008). [0pt] [3] Kyaw Sint, Boyang Wang and Petr Kral, JACS, ASAP (2008).

  14. Atrial Fibrillation and SCN5A Variants

    PubMed Central

    Savio-Galimberti, Eleonora; Darbar, Dawood

    2014-01-01

    Although atrial fibrillation (AF) is clinically and genetically a highly heterogeneous disease, recent studies suggest that the arrhythmia may arise because of interactions between genetic and acquired risk factors – the so called “double-hit” hypothesis. Genome-wide association studies have identified common AF susceptibility loci, and linkage analysis and candidate gene approaches have identified mutations in genes that encode for cardiac ion channels and signaling proteins; however, most of the heritability of AF still remains unexplained. The voltage-dependent cardiac sodium channel, encoded by SCN5A, conducts the main cardiac inward sodium current (INa) and is responsible for the upstroke of the atrial action potential. Mutations in SCN5A, which encodes the α-subunit of the NaV1.5 channel, have been linked with increased susceptibility to not only AF but also ventricular arrhythmias (long QT syndrome, Brugada syndrome), progressive cardiac conduction disease, and overlap syndromes with mixed arrhythmia phenotypes. Over the last decade, functional characterization of SCN5A mutations by expressing the channel in heterologous expression systems and applying cellular electrophysiological techniques has not only advanced our understanding of molecular mechanisms of AF but also potentially identified a mechanism-based approach to treating this common and morbid condition. PMID:25484998

  15. What is the role played by organic matter fractions from different sieve-size particles in the development of soil water repellency? A case study using analytical pyrolysis.

    NASA Astrophysics Data System (ADS)

    Jiménez-Morillo, Nicasio T.; González-Pérez, José A.; González-Vila, Francisco J.; Zavala, Lorena M.; Jordán, Antonio; Jiménez-González, Marco A.

    2014-05-01

    size fraction and SOM content. The most severe WR was detected in QS for all sieve size fractions, followed by the finer fractions form PA, PP and HH samples, which that also shows the highest SOM content, ranging between 20.9% (PP) and 46.9% (QS). Coarser soil fractions (1-2 mm) under PA, PP and HH showed the highest long-chain-even C numbered fatty acids (LCE-FA) in the order PP>PA>HH. No fatty acids were detected neither in sieve fractions 0.25-1, 0.05-0.25 and <0.05 mm from HH samples nor in PA and PP (0.25-1 mm samples). A significant relation was observed between SOM content and severity of soil WR in QS samples and finer fractions of other samples, which is in agreement with previous findings (GOrdillo-Rivero et al., 2013; Jordán et al., 2011). In contrast, 1-2 mm sieve fractions from PP, PA and HH soils showed high severity of soil WR and relatively low SOM contents. This could be explained by a low degree of evolution of organic residues with higher alkane/alkene CPI values and to the presence of a higher diversity of fatty acid structures. These results suggest that soil WR appears as a consequence of lipid compounds in soil. Some similarities were found in the organic molecular assemblages in PA and PP samples, suggesting a fingerprint of pine residues in PA samples, resulting from ancient pine forests. This finding may be also explained by the existence of exogenous organic inputs associated to fine soil particles from border areas of pine forests. REFERENCES de la Rosa, J.M., González-Pérez, J.A., González-Vila, F.J., Knicker, H., Araújo, M.F. 2011. Characterization of wildfire effects on soil organic matter using analytical pyrolysis. Geoderma 191, 24-30. González-Pérez, J.A., González-Vila, F.J., Arias, M.E., Rodríguez, J., de la Rosa, J.M., Marañón, T., Clemente, L. 2011. Geochemical and ecological significance of soil lipids under Rhododendron ponticum stands. Environmental Chemistry Letters 9, 453-464. Gordillo-Rivero, A.J., Garc

  16. What is the role played by organic matter fractions from different sieve-size particles in the development of soil water repellency? A case study using analytical pyrolysis.

    NASA Astrophysics Data System (ADS)

    Jiménez-Morillo, Nicasio T.; González-Pérez, José A.; González-Vila, Francisco J.; Zavala, Lorena M.; Jordán, Antonio; Jiménez-González, Marco A.

    2014-05-01

    size fraction and SOM content. The most severe WR was detected in QS for all sieve size fractions, followed by the finer fractions form PA, PP and HH samples, which that also shows the highest SOM content, ranging between 20.9% (PP) and 46.9% (QS). Coarser soil fractions (1-2 mm) under PA, PP and HH showed the highest long-chain-even C numbered fatty acids (LCE-FA) in the order PP>PA>HH. No fatty acids were detected neither in sieve fractions 0.25-1, 0.05-0.25 and <0.05 mm from HH samples nor in PA and PP (0.25-1 mm samples). A significant relation was observed between SOM content and severity of soil WR in QS samples and finer fractions of other samples, which is in agreement with previous findings (GOrdillo-Rivero et al., 2013; Jordán et al., 2011). In contrast, 1-2 mm sieve fractions from PP, PA and HH soils showed high severity of soil WR and relatively low SOM contents. This could be explained by a low degree of evolution of organic residues with higher alkane/alkene CPI values and to the presence of a higher diversity of fatty acid structures. These results suggest that soil WR appears as a consequence of lipid compounds in soil. Some similarities were found in the organic molecular assemblages in PA and PP samples, suggesting a fingerprint of pine residues in PA samples, resulting from ancient pine forests. This finding may be also explained by the existence of exogenous organic inputs associated to fine soil particles from border areas of pine forests. REFERENCES de la Rosa, J.M., González-Pérez, J.A., González-Vila, F.J., Knicker, H., Araújo, M.F. 2011. Characterization of wildfire effects on soil organic matter using analytical pyrolysis. Geoderma 191, 24-30. González-Pérez, J.A., González-Vila, F.J., Arias, M.E., Rodríguez, J., de la Rosa, J.M., Marañón, T., Clemente, L. 2011. Geochemical and ecological significance of soil lipids under Rhododendron ponticum stands. Environmental Chemistry Letters 9, 453-464. Gordillo-Rivero, A.J., Garc

  17. Use of weather radar for flood forecasting in the Sieve River Basin: A sensitivity analysis

    SciTech Connect

    Pessoa, M.L.; Bras, R.L.; Williams, E.R. )

    1993-03-01

    Weather radar, in combination with a distributed rainfall-runoff model, promises to significantly improve real-time flood forecasting. This paper investigates the value of radar-derived precipitation in forecasting streamflow in the Sieve River basin, near Florence, Italy. The basin is modeled with a distributed rainfall-runoff model that exploits topographic information available from digital elevation maps. The sensitivity of the flood forecast to various properties of the radar-derived rainfall is studied. It is found that use of the proper radar reflectivity-rainfall intensity (Z-R) relationship is the most crucial factor in obtaining correct flood hydrographs. Errors resulting from spatially averaging radar rainfall are acceptable, but the use of discrete point information (i.e. raingage) can lead to serious problems. Reducing the resolution of the 5-min radar signal by temporally averaging over 15 and 30 min does not lead to major errors. Using 3-bit radar data (rather than the usual 8-bit data) to represent intensities results in significant operational savings without serious problems in hydrograph accuracy. 24 refs., 28 figs., 2 tabs.

  18. Synthesis, characterization, and mercury adsorption properties of hybrid mesoporous aluminosilicate sieve prepared with fly ash

    NASA Astrophysics Data System (ADS)

    Liu, Minmin; Hou, Li-an; Xi, Beidou; Zhao, Ying; Xia, Xunfeng

    2013-05-01

    A novel hybrid mesoporous aluminosilicate sieve (HMAS) was prepared with fly ash and impregnated with zeolite A precursors. This improved the mercury adsorption of HMAS compared to original MCM-41. The HMAS was characterized by X-ray diffraction (XRD), nitrogen adsorption-desorption, Fourier transform infrared (FTIR) analysis, transmission electron microscopy (TEM) images and 29Si and 27Al magic angle spinning nuclear magnetic resonance (MAS NMR) spectra. These showed that the HMAS structure was still retained after impregnated with zeolite A. But the surface area and pore diameter of HMAS decreased due to pore blockage. Adsorption of mercury from aqueous solution was studied on untreated MCM-41and HMAS. The mercury adsorption rate of HMAS was higher than that of origin MCM-41. The adsorption of mercury was investigated on HMAS regarding the pH of mercury solution, initial mercury concentration, and the reaction temperature. The experimental data fit well to Langmuir and Freundlich isotherm models. The Dublin-Radushkevich isotherm and the characterization show that the mercury adsorption on HMAS involved the ion-exchange mechanisms. In addition, the thermodynamic parameters suggest that the adsorption process was endothermic in nature. The adsorption of mercury on HMAS followed the first order kinetics.

  19. SANDY: A Matlab tool to estimate the sediment size distribution from a sieve analysis

    NASA Astrophysics Data System (ADS)

    Ruiz-Martínez, Gabriel; Rivillas-Ospina, Germán Daniel; Mariño-Tapia, Ismael; Posada-Vanegas, Gregorio

    2016-07-01

    This paper presents a new computational tool called SANDY© which calculates the sediment size distribution and its textural parameters from a sieved sediment sample using Matlab®. The tool has been developed for professionals involved in the study of sediment transport along coastal margins, estuaries, rivers and desert dunes. The algorithm uses several types of statistical analyses to obtain the main textural characteristics of the sediment sample (D50, mean, sorting, skewness and kurtosis). SANDY© includes the method of moments (geometric, arithmetic and logarithmic approaches) and graphical methods (geometric, arithmetic and mixed approaches). In addition, it provides graphs of the sediment size distribution and its classification. The computational tool automatically exports all the graphs as enhanced metafile images and the final report is also exported as a plain text file. Parameters related to bed roughness such as Nikuradse and roughness length are also computed. Theoretical depositional environments are established by a discriminant function analysis. Using the uniformity coefficient the hydraulic conductivity of the sand as well as the porosity and void ratio of the sediment sample are obtained. The maximum relative density related to sand compaction is also computed. The Matlab® routine can compute one or several samples. SANDY© is a useful tool for estimating the sediment textural parameters which are the basis for studies of sediment transport.

  20. Synthesis, characterization, and mercury adsorption properties of hybrid mesoporous aluminosilicate sieve prepared with fly ash

    PubMed Central

    Liu, Minmin; Hou, Li-an; Xi, Beidou; Zhao, Ying; Xia, Xunfeng

    2013-01-01

    A novel hybrid mesoporous aluminosilicate sieve (HMAS) was prepared with fly ash and impregnated with zeolite A precursors. This improved the mercury adsorption of HMAS compared to original MCM-41. The HMAS was characterized by X-ray diffraction (XRD), nitrogen adsorption–desorption, Fourier transform infrared (FTIR) analysis, transmission electron microscopy (TEM) images and 29Si and 27Al magic angle spinning nuclear magnetic resonance (MAS NMR) spectra. These showed that the HMAS structure was still retained after impregnated with zeolite A. But the surface area and pore diameter of HMAS decreased due to pore blockage. Adsorption of mercury from aqueous solution was studied on untreated MCM-41and HMAS. The mercury adsorption rate of HMAS was higher than that of origin MCM-41. The adsorption of mercury was investigated on HMAS regarding the pH of mercury solution, initial mercury concentration, and the reaction temperature. The experimental data fit well to Langmuir and Freundlich isotherm models. The Dublin–Radushkevich isotherm and the characterization show that the mercury adsorption on HMAS involved the ion-exchange mechanisms. In addition, the thermodynamic parameters suggest that the adsorption process was endothermic in nature. The adsorption of mercury on HMAS followed the first order kinetics. PMID:23687400

  1. Proteomics and metabolomics analyses reveal the cucurbit sieve tube system as a complex metabolic space.

    PubMed

    Hu, Chaoyang; Ham, Byung-Kook; El-Shabrawi, Hattem M; Alexander, Danny; Zhang, Dabing; Ryals, John; Lucas, William J

    2016-09-01

    The plant vascular system, and specifically the phloem, plays a pivotal role in allocation of fixed carbon to developing sink organs. Although the processes involved in loading and unloading of sugars and amino acids are well characterized, little information is available regarding the nature of other metabolites in the sieve tube system (STS) at specific sites along the pathway. Here, we elucidate spatial features of metabolite composition mapped with phloem enzymes along the cucurbit STS. Phloem sap (PS) was collected from the loading (source), unloading (apical sink region) and shoot-root junction regions of cucumber, watermelon and pumpkin. Our PS analyses revealed significant differences in the metabolic and proteomic profiles both along the source-sink pathway and between the STSs of these three cucurbits. In addition, metabolite profiles established for PS and vascular tissue indicated the presence of distinct compositions, consistent with the operation of the STS as a unique symplasmic domain. In this regard, at various locations along the STS we could map metabolites and their related enzymes to specific metabolic pathways. These findings are discussed with regard to the function of the STS as a unique and highly complex metabolic space within the plant vascular system. PMID:27155400

  2. New correlation for sieve-tray point efficiency, entrainment, and section efficiency

    SciTech Connect

    Bennett, D.L.; Watson, D.N.; Wiescinski, M.A.

    1997-06-01

    A comprehensive composite database for distillation sieve-tray efficiency is used to develop point efficiency and entrainment correlations based on a model that considers the fluid on the distillation tray to be contained in a liquid-continuous region near the tray deck and a vapor-continuous region on top of the liquid-continuous region. This model allows estimates of the portion of the mass transfer resistance that occurs on the liquid side and vapor side of the interface. For most cases, most of the mass transfer occurs within the liquid-continuous region. The liquid side resistance is often significant. The entrainment correlation is consistent with the work of bennett et al., which relates entrainment to the ratios of the liquid to vapor density and the forth height to the tray spacing. A simple liquid continuous-only mass-transfer model containing only four empirical parameters correlates the point efficiency data to within 6.4%. Despite a twofold change in vapor Schmidt number, no dependency on vapor Schmidt number is seen. Important dimensionless groupings are the Reynolds number based on the hole velocity, effective froth density, ratio of the liquid inventory to the perforation diameter, and fraction of the tray area perforated. Mathematically simple and accurate methods allow the prediction of the section efficiency for trays operating in cross or parallel flow. They address vapor and liquid mixing, entrainment and a criterion to avoid significant degradation of the tray efficiency due to weeping.

  3. Proteomics and metabolomics analyses reveal the cucurbit sieve tube system as a complex metabolic space.

    PubMed

    Hu, Chaoyang; Ham, Byung-Kook; El-Shabrawi, Hattem M; Alexander, Danny; Zhang, Dabing; Ryals, John; Lucas, William J

    2016-09-01

    The plant vascular system, and specifically the phloem, plays a pivotal role in allocation of fixed carbon to developing sink organs. Although the processes involved in loading and unloading of sugars and amino acids are well characterized, little information is available regarding the nature of other metabolites in the sieve tube system (STS) at specific sites along the pathway. Here, we elucidate spatial features of metabolite composition mapped with phloem enzymes along the cucurbit STS. Phloem sap (PS) was collected from the loading (source), unloading (apical sink region) and shoot-root junction regions of cucumber, watermelon and pumpkin. Our PS analyses revealed significant differences in the metabolic and proteomic profiles both along the source-sink pathway and between the STSs of these three cucurbits. In addition, metabolite profiles established for PS and vascular tissue indicated the presence of distinct compositions, consistent with the operation of the STS as a unique symplasmic domain. In this regard, at various locations along the STS we could map metabolites and their related enzymes to specific metabolic pathways. These findings are discussed with regard to the function of the STS as a unique and highly complex metabolic space within the plant vascular system.

  4. Particle Size (Sieving) and Enthalpy (Acid Calorimetry) Analysis of Single-Pull K East Basin Floor and Pit Sludges

    SciTech Connect

    PR Bredt; CH Delegard; AJ Schmidt; KL Silvers; BM Thornton; S Gano

    2000-12-22

    This report presents the results of particle size analyses and calorimetry testing performed on selected single-pull sludge samples collected from the Hanford K East Basin between December 1998 and June 1999. The samples were collected as isolated cores predominantly from areas that had not been previously sampled (e.g., North Loadout Pit, Dummy Elevator Pit, Tech View Pit), or from areas in which the sludge composition had been altered since the last sampling (e.g., Weasel Pit). Particle size analyses were performed by washing wet sludge samples through a series of four sieves with openings of 250, 500, 1410, and 4000 {micro}m. The loaded sieves were weighed before and after drying to obtain wet and dry particle size distributions. Knowledge of the particle size distribution is needed to design and predict the performance of the systems that will be used to retrieve, transport, and recover sludge. Also, sieving provides an opportunity to observe the components in the sludge. For example, during sieving of the sludge sample from the North Loadout Pit, significant quantities of organic ion exchange beads were observed. The uranium metal content and the particle size of the uranium metal in the K Basin sludge will largely determine the chemical reactivity of the sludge. In turn, the designs for the sludge handling and storage systems must be compatible with the reactivity of the sludge. Therefore, acid calorimetry was performed to estimate the uranium metal content of the sludge. For this testing, sludge samples were dissolved in nitric acid within a calibrated adiabatic calorimeter. The resulting dissolution enthalpy data were then used to discriminate between metallic uranium ({minus}3750 J/g in nitric acid) and uranium oxide ({minus}394 J/g in nitric acid). Results from this testing showed that the single-pull sludge samples contained little or no uranium metal.

  5. Preliminary report on the baseline thermal and hydraulic performance tests of a sieve tray direct contact heat exchanger

    SciTech Connect

    Mines, G.L.

    1982-11-01

    A sieve tray direct contact heat exchanger was designed, built and then tested in a binary power cycle at the Raft River geothermal test site. A series of baseline thermal and hydraulic tests were conducted with an isobutane working fluid. The evaluation of these tests is reported. The testing of the DCHX confirmed that the repeated forming and coalescence of the working fluid drops in the sieve tray column produce excellent heat transfer performance. Tray thermal efficiencies were at or above the design value of 70% and the pinch points were well under the design goal of 1/sup 0/F (too small to be measured with installed instrumentation). From a hydraulic standpoint, the column operated at the working fluid velocities from the plate holes corresponding to the predicted condition of maximum total drop surface area (or minimum drop size) when the unit was operating near the flooding limits, or throughputs. This is the recommended working fluid hole velocity for use in designing sieve tray columns. The geothermal flow limits encountered (at flooding) corresponded roughly to the thermal rise velocity of a 1/32-inch drop. This is a drop size commonly used for specifying the terminal velocity (or continuous fluid velocity) in the design of columns for mass transfer applications.

  6. Location of caspase 3-like protease in the development of sieve element and tracheary element of stem in Cucurbita moschata.

    PubMed

    Hao, Xia; Qian, Jie; Xu, Shan; Song, Xin; Zhu, Jian

    2008-12-01

    The casepase is considered to regulate the process of programmed cell death in the development of organisms. In this study, caspase 3-like protease was detected by immunohistochemistry and immunoelectron microscopy during the development of sieve element and tracheary element of stem in Cucurbita moschata Duch. Antibody with brown color (under light microscopy) and gold particles (under transmission electron microscopy) for detecting caspase 3-like protease was mainly displayed in inner phloem, external phloem and xylem in the region close to procambium. From the results it was considered that caspase 3-like protease did exist in vascular elements and played different roles during the development of sieve and tracheary elements, and different types of programmed cell death might be carried out. The caspase 3-like protease mainly participated in making cytoplasmic streaming cease and in degrading P-protein bodies; however, it rarely participated in the function for signal transferring in the developmental sieve element. However, it might induce calcium accumulation for rupturing the tonoplast in the signal of PCD in the developmental tracheary element.

  7. Effect of sample area and sieve size on benthic macrofaunal community condition assessments in California enclosed bays and estuaries.

    PubMed

    Hammerstrom, Kamille K; Ranasinghe, J Ananda; Weisberg, Stephen B; Oliver, John S; Fairey, W Russell; Slattery, Peter N; Oakden, James M

    2012-10-01

    Benthic macrofauna are used extensively for environmental assessment, but the area sampled and sieve sizes used to capture animals often differ among studies. Here, we sampled 80 sites using 3 different sized sampling areas (0.1, 0.05, 0.0071 m(2)) and sieved those sediments through each of 2 screen sizes (0.5, 1 mm) to evaluate their effect on number of individuals, number of species, dominance, nonmetric multidimensional scaling (MDS) ordination, and benthic community condition indices that are used to assess sediment quality in California. Sample area had little effect on abundance but substantially affected numbers of species, which are not easily scaled to a standard area. Sieve size had a substantial effect on both measures, with the 1-mm screen capturing only 74% of the species and 68% of the individuals collected in the 0.5-mm screen. These differences, though, had little effect on the ability to differentiate samples along gradients in ordination space. Benthic indices generally ranked sample condition in the same order regardless of gear, although the absolute scoring of condition was affected by gear type. The largest differences in condition assessment were observed for the 0.0071-m(2) gear. Benthic indices based on numbers of species were more affected than those based on relative abundance, primarily because we were unable to scale species number to a common area as we did for abundance. PMID:20938972

  8. Double-sieving-defective aminoacyl-tRNA synthetase causes protein mistranslation and affects cellular physiology and development

    PubMed Central

    Lu, Jiongming; Bergert, Martin; Walther, Anita; Suter, Beat

    2014-01-01

    Aminoacyl-tRNA synthetases (aaRSs) constitute a family of ubiquitously expressed essential enzymes that ligate amino acids to their cognate tRNAs for protein synthesis. Recently, aaRS mutations have been linked to various human diseases; however, how these mutations lead to diseases has remained unclear. In order to address the importance of aminoacylation fidelity in multicellular organisms, we generated an amino-acid double-sieving model in Drosophila melanogaster using phenylalanyl-tRNA synthetase (PheRS). Double-sieving-defective mutations dramatically misacylate non-cognate Tyr, induce protein mistranslation and cause endoplasmic reticulum stress in flies. Mutant adults exhibit many defects, including loss of neuronal cells, impaired locomotive performance, shortened lifespan and smaller organ size. At the cellular level, the mutations reduce cell proliferation and promote cell death. Our results also reveal the particular importance of the first amino-acid recognition sieve. Overall, these findings provide new mechanistic insights into how malfunctioning of aaRSs can cause diseases. PMID:25427601

  9. HydrogeoSieveXL: an Excel-based tool to estimate hydraulic conductivity from grain-size analysis

    NASA Astrophysics Data System (ADS)

    Devlin, J. F.

    2015-04-01

    For over a century, hydrogeologists have estimated hydraulic conductivity (K) from grain-size distribution curves. The benefits of the practice are simplicity, cost, and a means of identifying spatial variations in K. Many techniques have been developed over the years, but all suffer from similar shortcomings: no accounting of heterogeneity within samples (i.e., aquifer structure is lost), loss of grain packing characteristics, and failure to account for the effects of overburden pressure on K. In addition, K estimates can vary by an order of magnitude between the various methods, and it is not generally possible to identify the best method for a given sample. The drawbacks are serious, but the advantages have seen the use of grain-size distribution curves for K estimation continue, often using a single selected method to estimate K in a given project. In most cases, this restriction results from convenience. It is proposed here that extending the analysis to include several methods would be beneficial since it would provide a better indication of the range of K that might apply. To overcome the convenience limitation, an Excel-based spreadsheet program, HydrogeoSieveXL, is introduced here. HydrogeoSieveXL is a freely available program that calculates K from grain-size distribution curves using 15 different methods. HydrogeoSieveXL was found to calculate K values essentially identical to those reported in the literature, using the published grain-size distribution curves.

  10. NOTE: The use of molecular sieves to simulate hot lesions in 18F-fluorodeoxyglucose—positron emission tomography imaging

    NASA Astrophysics Data System (ADS)

    Matheoud, R.; Secco, C.; Ridone, S.; Inglese, E.; Brambilla, M.

    2008-04-01

    We investigated the use of a kind of zeolite, the Bowie chabazite, to produce radioactive sources of different shapes, dimensions and activity concentrations that can be used for lesion simulation in positron emission tomography (PET) imaging. The 18F-fluorodeoxyglucose (18F-FDG) uptake of a group of 12 zeolites was studied as a function of their weight (120-1520 mg) and of the activity concentration of the 18F-FDG solution (1-37 MBq ml-1), using a multiple linear regression model. The reproducibility, homogeneity and stability over time of the 18F-FDG uptake were assessed. The fit of the regression model is good (r2 = 0.83). This relation allows the production of zeolites of a desired 18F-FDG activity using knowledge of the concentration of the soaking solution and the weight of the zeolite. The reproducibility of the 18F-FDG uptake after heating the zeolites is elevated (CV% = 3.68). The almost complete regeneration of the zeolites allows us to reuse them in successive experiments. The stability of the 18F-FDG uptake on zeolites is far from ideal. When placed in a saline solution the 'activated' zeolites release the 18F-FDG with an effective half-time of 53 min. The sealing of the zeolites in plastic film bags has been demonstrated to be effective in preventing any release of 18F-FDG. These features, together with their variable dimensions and shapes, make them ideal 18F-FDG sources with a fixed target-to-background ratio that can be placed anywhere in a phantom to study lesion detectability in PET imaging.

  11. Photocatalytic Degradation of Di-n-Butyl Phthalate by N-Doped Ti/13X/MCM-41 Molecular Sieve.

    PubMed

    Tao, Hong; Nguyen, Nhat-Thien; Heil, Xiao-Hui; Liang, Xiao; Chang, Chang-Tang

    2015-07-01

    Di-n-butyl phthalate (DBP) is a type of phthalate ester, and has been classified as an environmental endocrine disruptor. It causes serious harm to the environment and humans and it is found widely in air, waste water, rivers and soil. In recent years, an increasing number of studies examined the removal of DBP. Photocatalytic degradation has been of particular interest because of its efficient and thorough advantages and is the focus of this study. Here we use a composite material of N-Ti/13X/MCM-41, synthesized, using 13X and tetraethyl orthosilicate as raw material, CTAB as structural template, tetrabutyl titanate and urea under hydrothermal conditions. The optimized experimental conditions, such as, Si/Al (molar ratio), pH value, crystallization time, calcination temperature and N/Ti (molar ratio), were tested using photodegradation experiments of DBP. The samples were characterized by XRD, TEM, FT-IR, N2 adsorption-desorption. Experimental results reveal the surface area of the N-Ti/13X/MCM-41 to be 664 m2 g(-1) and the average pore sizes to be 2.79 nm. TEM micrographs showed the N-Ti/13X/MCM-41 consists of aggregates of spherical particles, similar to the shapes associated with standard MCM-41 synthesized under basic conditions. Photocatalytic degradation experimental results revealed that optimal synthesis of the composite material occurs when Si/Al = 15, pH = 9.0, crystallization time is 48 hours, calcination temperature is 350 °C and the N/Ti ratios is 2.0. Under such conditions, the degradation efficiency of DBP more was found to be more than 90%.

  12. Tritium test of cryogenic molecular sieve bed for He GDC gas cleanup by 60 SLM test loop

    SciTech Connect

    Enoeda, Mikio; Kawamura, Yoshinori; Okuno, Kenji

    1996-12-31

    This work presents demonstrative test results of CMSB by simulated helium glow discharge exhaust gas condition in 60 l/min of flow rate. This work focused on H{sub 2} and HT adsorption and regeneration performance of CMSB and optimum regeneration procedure, so that the operation cycle time becomes smaller. Test results showed consistency with bench-scale experiments. Obtained engineering data are applicable for the design of the CMSB process for ITER He GDC gas cleanup. As the results of this work, it was demonstrated that CMSB process could clean up 54.3 SLM of He stream with H{sub 2}(400) ppm+HT(0.5 ppm). Regeneration performance in various total pressure were obtained and evaluated by the calculation and clarified necessary information for determining the optimum regeneration procedure of CMSB which allow continuous operation in the shorter period of operation cycle (adsorption and regeneration). 6 refs., 5 figs., 1 tab.

  13. A tale of two neglected systems—structure and function of the thin- and thick-walled sieve tubes in monocotyledonous leaves

    PubMed Central

    Botha, C. E. J.

    2013-01-01

    There is a large body of information relating to the ontogeny, development and the vasculature of eudicotyledonous leaves. However, there is less information available concerning the vascular anatomy of monocotyledonous leaves. This is surprising, given that there are two uniquely different phloem systems present in large groups such as grasses and sedges. Monocotyledonous leaves contain marginal, large, intermediate, and small longitudinal veins that are interconnected by numerous transverse veins. The longitudinal veins contain two metaphloem sieve tube types, which, based upon their ontogeny and position within the phloem, are termed early (thin-walled) and late (thick-walled) sieve tubes. Early metaphloem comprises sieve tubes, companion cells and vascular parenchyma (VP) cells, whilst the late metaphloem, contains thick-walled sieve tubes (TSTs) that lack companion cells. TSTs are generally adjacent to, or no more than one cell removed from the metaxylem. Unlike thin-walled sieve tube (ST) -companion cell complexes, TSTs are connected to parenchyma by pore-plasmodesma units and are generally symplasmically isolated from the STs. This paper addresses key structural and functional differences between thin- and thick-walled sieve tubes and explores the unique advantages of alternate transport strategies that this 5–7 million years old dual system may offer. It would seem that these two systems may enhance, add to, or play a significant role in increasing the efficiency of solute retrieval as well as of assimilate transfer. PMID:23964280

  14. Effect of milling and sieving on functionality of dry powder inhalation products.

    PubMed

    Steckel, H; Markefka, P; teWierik, H; Kammelar, R

    2006-02-17

    Alpha-lactose monohydrate is the standard excipient used as diluent or carrier in dry powder inhaler (DPI) formulations. Earlier studies have already revealed that raw materials for the production of inhalation grade lactose have to be carefully selected in order to avoid batch-to-batch variability. In the present study, the effect of milling and milling intensity on the flow properties and the physico-chemical characteristics of lactose crystals has been determined. The milled lactoses were then further processed by sieving to give lactose qualities with identical size distribution data, but different batch history (non-milled and milled at different conditions). These were then used to manufacture low concentration (0.25%) drug blends with the model drugs salbutamol sulphate (SBS) and beclometasonedipropionate (BDP); the blends were analysed with a Multistage Liquid Impinger (MLI) after delivery from an Easyhaler and an Aerolizer device. It could be shown that gentle milling already results in surface defects on the lactose crystal which are further enhanced by using a higher milling intensity. Produced fine lactose particles during the milling process strongly adhere to the lactose surface and cannot be removed by compressed air which is used for the particle sizing. By trend, a higher milling intensity resulted in higher fine particle fractions (FPF) with both devices. Also, SBS was found to generally give higher fine particle fractions than BDP, independent from the device used. In conclusion, lactose pre-treatment by gentle or strong milling affects the carrier surface and thereby the aerosolization properties of drug/lactose blends produced. PMID:16377105

  15. Electrophysiological approach to determine kinetic parameters of sucrose uptake by single sieve elements or phloem parenchyma cells in intact Vicia faba plants

    PubMed Central

    Hafke, Jens B.; Höll, Sabina-Roxana; Kühn, Christina; van Bel, Aart J. E.

    2013-01-01

    Apart from cut aphid stylets in combination with electrophysiology, no attempts have been made thus far to measure in vivo sucrose-uptake properties of sieve elements. We investigated the kinetics of sucrose uptake by single sieve elements and phloem parenchyma cells in Vicia faba plants. To this end, microelectrodes were inserted into free-lying phloem cells in the main vein of the youngest fully-expanded leaf, half-way along the stem, in the transition zone between the autotrophic and heterotrophic part of the stem, and in the root axis. A top-to-bottom membrane potential gradient of sieve elements was observed along the stem (−130 mV to −110 mV), while the membrane potential of the phloem parenchyma cells was stable (approx. −100 mV). In roots, the membrane potential of sieve elements dropped abruptly to −55 mV. Bathing solutions having various sucrose concentrations were administered and sucrose/H+-induced depolarizations were recorded. Data analysis by non-linear least-square data fittings as well as by linear Eadie–Hofstee (EH) -transformations pointed at biphasic Michaelis–Menten kinetics (2 MM, EH: Km1 1.2–1.8 mM, Km2 6.6–9.0 mM) of sucrose uptake by sieve elements. However, Akaike's Information Criterion (AIC) favored single MM kinetics. Using single MM as the best-fitting model, Km values for sucrose uptake by sieve elements decreased along the plant axis from 1 to 7 mM. For phloem parenchyma cells, higher Km values (EH: Km1 10 mM, Km2 70 mM) as compared to sieve elements were found. In preliminary patch-clamp experiments with sieve-element protoplasts, small sucrose-coupled proton currents (−0.1 to −0.3 pA/pF) were detected in the whole-cell mode. In conclusion (a) Km values for sucrose uptake measured by electrophysiology are similar to those obtained with heterologous systems, (b) electrophysiology provides a useful tool for in situ determination of Km values, (c) As yet, it remains unclear if one or two uptake systems are involved

  16. Charge-selective gate of arrayed MWCNTs for ultra high-efficient biomolecule enrichment by nano-electrostatic sieving (NES).

    PubMed

    Wu, Jen-Kuei; Wu, Yi-Shiuan; Yang, Chung-Shi; Tseng, Fan-Gang

    2013-05-15

    We report a rapid and highly-efficient biomolecule preconcentrating device based on nano-electrostatic sieving (NES) mechanism that is facilitated by multi-nanofluidic channels operated in parallel. The opening of these nanochannels is regulated by tunable charges that are generated on arrayed multi-walled carbon nanotubes (MWCNTs) gate. The NES device is fabricated by standard photolithography and plasma-enhanced chemical vapor deposition (PECVD) techniques, followed by subsequent deposition of parylene (poly(p-xylylene))-C on vertically grown MWCNTs in order to obtain arrayed multi-nanochannels with mean pore sizes that are comparable to the thickness of an electrical double layer (EDL). The enrichment efficiency for charged analytes is dependent on electrostatic repulsion, which is regulated by the distribution of the local electric field on the MWCNTs gate. The NES device exhibits polarity selectivity on the analytes and performs efficient collection and separation of biomolecules by probing the surface charge density dependence on the applied gate field. A tunable gate of the parylene-MWCNT nanochannels was used as size sieving devices for nano-scale biomolecules. The experimental results for the collection of FITC-labeled bovine serum albumin (BSA, 0.033nM) were as high as nearly 10(6) fold after only 45min. These data are attributed to the in-parallel molecule sieving process as conducted by the many nanochannels formed among the MWCNTs. This device allows uncharged polar molecules, such as water, to rapidly pass through thus enable highly efficient bio-molecule concentration for the application to ultra-high sensitive biosensing. PMID:23391690

  17. Trend analysis of Trichinella in a red fox population from a low endemic area using a validated artificial digestion and sequential sieving technique.

    PubMed

    Franssen, Frits; Deksne, Gunita; Esíte, Zanda; Havelaar, Arie; Swart, Arno; van der Giessen, Joke

    2014-01-01

    Freezing of fox carcasses to minimize professional hazard of infection with Echinococcus multilocularis is recommended in endemic areas, but this could influence the detection of Trichinella larvae in the same host species. A method based on artificial digestion of frozen fox muscle, combined with larva isolation by a sequential sieving method (SSM), was validated using naturally infected foxes from Latvia. The validated SSM was used to detect dead Trichinella muscle larvae (ML) in frozen muscle samples of 369 red foxes from the Netherlands, of which one fox was positive (0.067 larvae per gram). This result was compared with historical Trichinella findings in Dutch red foxes. Molecular analysis using 5S PCR showed that both T. britovi and T. nativa were present in the Latvian foxes, without mixed infections. Of 96 non-frozen T. britovi ML, 94% was successfully sequenced, whereas this was the case for only 8.3% of 72 frozen T. britovi ML. The single Trichinella sp. larva that was recovered from the positive Dutch fox did not yield PCR product, probably due to severe freeze-damage. In conclusion, the SSM presented in this study is a fast and effective method to detect dead Trichinella larvae in frozen meat. We showed that the Trichinella prevalence in Dutch red fox was 0.27% (95% CI 0.065-1.5%), in contrast to 3.9% in the same study area fifteen years ago. Moreover, this study demonstrated that the efficacy of 5S PCR for identification of Trichinella britovi single larvae from frozen meat is not more than 8.3%. PMID:25431178

  18. Removal of heavy metals and arsenic from a co-contaminated soil by sieving combined with washing process.

    PubMed

    Liao, Xiaoyong; Li, You; Yan, Xiulan

    2016-03-01

    Batch experiments were conducted with a heavy metals and arsenic co-contaminated soil from an abandoned mine to evaluate the feasibility of a remediation technology that combines sieving with soil washing. Leaching of the arsenic and heavy metals from the different particle size fractions was found to decrease in the order: <0.1, 2-0.1, and >2mm. With increased contact time, the concentration of heavy metals in the leachate was significantly decreased for small particles, probably because of adsorption by the clay soil component. For the different particle sizes, the removal efficiencies for Pb and Cd were 75%-87%, and 61%-77% for Zn and Cu, although the extent of removal was decreased for As and Cr at <45%. The highest efficiency by washing for Pb, Cd, Zn, and As was from the soil particles >2mm, although good metal removal efficiencies were also achieved in the small particle size fractions. Through SEM-EDS observations and correlation analysis, the leaching regularity of the heavy metals and arsenic was found to be closely related to Fe, Mn, and Ca contents of the soil fractions. The remediation of heavy metal-contaminated soil by sieving combined with soil washing was proven to be efficient, and practical remediation parameters were also recommended.

  19. Removal of heavy metals and arsenic from a co-contaminated soil by sieving combined with washing process.

    PubMed

    Liao, Xiaoyong; Li, You; Yan, Xiulan

    2016-03-01

    Batch experiments were conducted with a heavy metals and arsenic co-contaminated soil from an abandoned mine to evaluate the feasibility of a remediation technology that combines sieving with soil washing. Leaching of the arsenic and heavy metals from the different particle size fractions was found to decrease in the order: <0.1, 2-0.1, and >2mm. With increased contact time, the concentration of heavy metals in the leachate was significantly decreased for small particles, probably because of adsorption by the clay soil component. For the different particle sizes, the removal efficiencies for Pb and Cd were 75%-87%, and 61%-77% for Zn and Cu, although the extent of removal was decreased for As and Cr at <45%. The highest efficiency by washing for Pb, Cd, Zn, and As was from the soil particles >2mm, although good metal removal efficiencies were also achieved in the small particle size fractions. Through SEM-EDS observations and correlation analysis, the leaching regularity of the heavy metals and arsenic was found to be closely related to Fe, Mn, and Ca contents of the soil fractions. The remediation of heavy metal-contaminated soil by sieving combined with soil washing was proven to be efficient, and practical remediation parameters were also recommended. PMID:26969066

  20. Similar Intracellular Location and Stimulus Reactivity, but Differential Mobility of Tailless (Vicia faba) and Tailed Forisomes (Phaseolus vulgaris) in Intact Sieve Tubes.

    PubMed

    Furch, Alexandra C U; Buxa, Stefanie V; van Bel, Aart J E

    2015-01-01

    Sieve elements of legumes contain forisomes-fusiform protein bodies that are responsible for sieve-tube occlusion in response to damage or wound signals. Earlier work described the existence of tailless and tailed forisomes. This study intended to quantify and compare location and position of tailless (in Vicia faba) and tailed (in Phaseolus vulgaris) forisomes inside sieve elements and to assess their reactivity and potential mobility in response to a remote stimulus. Location (distribution within sieve elements) and position (forisome tip contacts) of more than altogether 2000 forisomes were screened in 500 intact plants by laser scanning confocal microscopy in the transmission mode. Furthermore, we studied the dispersion of forisomes at different locations in different positions and their positional behaviour in response to distant heat shocks. Forisome distribution turned out to be species-specific, whereas forisome positions at various locations were largely similar in bushbean (Phaseolus) and broadbean (Vicia). In general, the tailless forisomes had higher dispersion rates in response to heat shocks than the tailed forisomes and forisomes at the downstream (basal) end dispersed more frequently than those at the upstream end (apical). In contrast to the tailless forisomes that only oscillate in response to heat shocks, downstream-located tailed forisomes can cover considerable distances within sieve elements. This displacement was prevented by gentle rubbing of the leaf (priming) before the heat shock. Movement of these forisomes was also prohibited by Latrunculin A, an inhibitor of actin polymerization. The apparently active mobility of tailed forisomes gives credence to the idea that at least the latter forisomes are not free-floating, but connected to other sieve-element structures.

  1. Similar Intracellular Location and Stimulus Reactivity, but Differential Mobility of Tailless (Vicia faba) and Tailed Forisomes (Phaseolus vulgaris) in Intact Sieve Tubes.

    PubMed

    Furch, Alexandra C U; Buxa, Stefanie V; van Bel, Aart J E

    2015-01-01

    Sieve elements of legumes contain forisomes-fusiform protein bodies that are responsible for sieve-tube occlusion in response to damage or wound signals. Earlier work described the existence of tailless and tailed forisomes. This study intended to quantify and compare location and position of tailless (in Vicia faba) and tailed (in Phaseolus vulgaris) forisomes inside sieve elements and to assess their reactivity and potential mobility in response to a remote stimulus. Location (distribution within sieve elements) and position (forisome tip contacts) of more than altogether 2000 forisomes were screened in 500 intact plants by laser scanning confocal microscopy in the transmission mode. Furthermore, we studied the dispersion of forisomes at different locations in different positions and their positional behaviour in response to distant heat shocks. Forisome distribution turned out to be species-specific, whereas forisome positions at various locations were largely similar in bushbean (Phaseolus) and broadbean (Vicia). In general, the tailless forisomes had higher dispersion rates in response to heat shocks than the tailed forisomes and forisomes at the downstream (basal) end dispersed more frequently than those at the upstream end (apical). In contrast to the tailless forisomes that only oscillate in response to heat shocks, downstream-located tailed forisomes can cover considerable distances within sieve elements. This displacement was prevented by gentle rubbing of the leaf (priming) before the heat shock. Movement of these forisomes was also prohibited by Latrunculin A, an inhibitor of actin polymerization. The apparently active mobility of tailed forisomes gives credence to the idea that at least the latter forisomes are not free-floating, but connected to other sieve-element structures. PMID:26624625

  2. Molecular Comb Development

    SciTech Connect

    Ferrell, T.L.; Thundat, G.T.; Witkowski, C.E., III

    2007-07-17

    This CRADA was developed to enable ORNL to assist Protein Discovery, Inc. to develop a novel biomolecular separation system based on an ORNL patent application 'Photoelectrochemical Molecular Comb' by Thundat, Ferrell, and Brown. The Molecular Comb concept is based on creating light-induced charge carriers at a semiconductor-liquid interface, which is kept at a potential control such that a depletion layer is formed in the semiconductor. Focusing light from a low-power illumination source creates electron-hole pairs, which get separated in the depletion layer. The light-induced charge carriers reaching the surface attract oppositely charged biomolecules present in the solution. The solution is a buffer solution with very small concentrations of biomolecules. As the focused light is moved across the surface of the semiconductor-liquid interface, the accumulated biomolecules follow the light beam. A thin layer of gel or other similar material on the surface of the semiconductor can act as a sieving medium for separating the biomolecules according to their sizes.

  3. 42 CFR 5a.2 - Applicability.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 42 Public Health 1 2011-10-01 2011-10-01 false Applicability. 5a.2 Section 5a.2 Public Health PUBLIC HEALTH SERVICE, DEPARTMENT OF HEALTH AND HUMAN SERVICES GENERAL PROVISIONS RURAL PHYSICIAN... Public Health Service Act....

  4. 42 CFR 5a.2 - Applicability.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 42 Public Health 1 2010-10-01 2010-10-01 false Applicability. 5a.2 Section 5a.2 Public Health PUBLIC HEALTH SERVICE, DEPARTMENT OF HEALTH AND HUMAN SERVICES GENERAL PROVISIONS RURAL PHYSICIAN... Public Health Service Act....

  5. Comparison of radioactive transmission and mechanical properties of Portland cement and a modified cement with trommel sieve waste

    SciTech Connect

    Boncukcuoglu, Recep . E-mail: rboncuk@yahoo.com; Icelli, Orhan; Erzeneoglu, Salih; Muhtar Kocakerim, M.

    2005-06-01

    In this study, it was aimed to stabilize trommel sieve waste (TSW) occurring during manufacture of borax from tincal. The effects of TSW added on the mechanical properties and radioactive transmission of modified cement prepared by adding TSW to clinker was investigated. The properties which TSW as additive caused the cement to gain were tested and compared with normal Portland cement. Measurements have been made to determine variation of mass attenuation coefficients of TSW and cement by using an extremely narrow-collimated-beam transmission method in the energy range 15.746-40.930 keV with X-ray transmission method. The characteristic K{alpha} and K{beta} X-rays of the different elements (Zr, Mo, Ag, In, Sb, Ba and Pr) passed through TSW and cement were detected with a high-resolution Si(Li) detector. Results are presented and discussed in this paper.

  6. REE Sorption Study of Sieved -50 +100 mesh Media #1 in Brine #1 with Different Starting pH's at 70C

    SciTech Connect

    Gary Garland

    2015-07-21

    This dataset described shaker table experiments ran with sieved -50 +100 mesh media #1 in brine #1 that have 2ppm each of the 7 REE metals at different starting pH's of 3.5, 4.5, and 5.5. The experimental conditions are 2g media to 150mL of REE solution, at 70C.

  7. Sieve-based coreference resolution enhances semi-supervised learning model for chemical-induced disease relation extraction

    PubMed Central

    Le, Hoang-Quynh; Tran, Mai-Vu; Dang, Thanh Hai; Ha, Quang-Thuy; Collier, Nigel

    2016-01-01

    The BioCreative V chemical-disease relation (CDR) track was proposed to accelerate the progress of text mining in facilitating integrative understanding of chemicals, diseases and their relations. In this article, we describe an extension of our system (namely UET-CAM) that participated in the BioCreative V CDR. The original UET-CAM system’s performance was ranked fourth among 18 participating systems by the BioCreative CDR track committee. In the Disease Named Entity Recognition and Normalization (DNER) phase, our system employed joint inference (decoding) with a perceptron-based named entity recognizer (NER) and a back-off model with Semantic Supervised Indexing and Skip-gram for named entity normalization. In the chemical-induced disease (CID) relation extraction phase, we proposed a pipeline that includes a coreference resolution module and a Support Vector Machine relation extraction model. The former module utilized a multi-pass sieve to extend entity recall. In this article, the UET-CAM system was improved by adding a ‘silver’ CID corpus to train the prediction model. This silver standard corpus of more than 50 thousand sentences was automatically built based on the Comparative Toxicogenomics Database (CTD) database. We evaluated our method on the CDR test set. Results showed that our system could reach the state of the art performance with F1 of 82.44 for the DNER task and 58.90 for the CID task. Analysis demonstrated substantial benefits of both the multi-pass sieve coreference resolution method (F1 + 4.13%) and the silver CID corpus (F1 +7.3%). Database URL: SilverCID–The silver-standard corpus for CID relation extraction is freely online available at: https://zenodo.org/record/34530 (doi:10.5281/zenodo.34530).

  8. Looking inside phytoplasma-infected sieve elements: A combined microscopy approach using Arabidopsis thaliana as a model plant.

    PubMed

    Pagliari, Laura; Martini, Marta; Loschi, Alberto; Musetti, Rita

    2016-10-01

    Phytoplasmas are phloem-inhabiting plant pathogens that affect over one thousand plant species, representing a severe threat to agriculture. The absence of an effective curative strategy and the economic importance of many affected crops make a priority of studying how plants respond to phytoplasma infection. Nevertheless, the study of phytoplasmas has been hindered by the extreme difficulty of culturing them in vitro and by impediments to natural host plant surveys such as low phytoplasma titre, long plant life cycle and poor knowledge of natural host-plant biology. Stating correspondence between macroscopic symptoms of phytoplasma infected Arabidopsis thaliana and those observed in natural host plants, over the last decade some authors have started to use this plant as a model for studying phytoplasma-plant interactions. Nevertheless, the morphological and ultrastructural modifications occurring in A. thaliana tissues following phytoplasma infection have never been described in detail. In this work, we adopted a combined-microscopy approach to verify if A. thaliana can be considered a reliable model for the study of phytoplasma-plant interactions at the microscopical level. The consistent presence of phytoplasma in infected phloem allowed detailed study of the infection process and the relationship established by phytoplasmas with different components of the sieve elements. In infected A. thaliana, phytoplasmas induced strong disturbances of host plant development that were mainly due to phloem disorganization and impairment. Light microscopy showed collapse, necrosis and hyperplasia of phloem cells. TEM observations of sieve elements identified two common plant-responses to phytoplasma infection: phloem protein agglutination and callose deposition. PMID:27569416

  9. Looking inside phytoplasma-infected sieve elements: A combined microscopy approach using Arabidopsis thaliana as a model plant.

    PubMed

    Pagliari, Laura; Martini, Marta; Loschi, Alberto; Musetti, Rita

    2016-10-01

    Phytoplasmas are phloem-inhabiting plant pathogens that affect over one thousand plant species, representing a severe threat to agriculture. The absence of an effective curative strategy and the economic importance of many affected crops make a priority of studying how plants respond to phytoplasma infection. Nevertheless, the study of phytoplasmas has been hindered by the extreme difficulty of culturing them in vitro and by impediments to natural host plant surveys such as low phytoplasma titre, long plant life cycle and poor knowledge of natural host-plant biology. Stating correspondence between macroscopic symptoms of phytoplasma infected Arabidopsis thaliana and those observed in natural host plants, over the last decade some authors have started to use this plant as a model for studying phytoplasma-plant interactions. Nevertheless, the morphological and ultrastructural modifications occurring in A. thaliana tissues following phytoplasma infection have never been described in detail. In this work, we adopted a combined-microscopy approach to verify if A. thaliana can be considered a reliable model for the study of phytoplasma-plant interactions at the microscopical level. The consistent presence of phytoplasma in infected phloem allowed detailed study of the infection process and the relationship established by phytoplasmas with different components of the sieve elements. In infected A. thaliana, phytoplasmas induced strong disturbances of host plant development that were mainly due to phloem disorganization and impairment. Light microscopy showed collapse, necrosis and hyperplasia of phloem cells. TEM observations of sieve elements identified two common plant-responses to phytoplasma infection: phloem protein agglutination and callose deposition.

  10. Sieve-based coreference resolution enhances semi-supervised learning model for chemical-induced disease relation extraction.

    PubMed

    Le, Hoang-Quynh; Tran, Mai-Vu; Dang, Thanh Hai; Ha, Quang-Thuy; Collier, Nigel

    2016-07-01

    The BioCreative V chemical-disease relation (CDR) track was proposed to accelerate the progress of text mining in facilitating integrative understanding of chemicals, diseases and their relations. In this article, we describe an extension of our system (namely UET-CAM) that participated in the BioCreative V CDR. The original UET-CAM system's performance was ranked fourth among 18 participating systems by the BioCreative CDR track committee. In the Disease Named Entity Recognition and Normalization (DNER) phase, our system employed joint inference (decoding) with a perceptron-based named entity recognizer (NER) and a back-off model with Semantic Supervised Indexing and Skip-gram for named entity normalization. In the chemical-induced disease (CID) relation extraction phase, we proposed a pipeline that includes a coreference resolution module and a Support Vector Machine relation extraction model. The former module utilized a multi-pass sieve to extend entity recall. In this article, the UET-CAM system was improved by adding a 'silver' CID corpus to train the prediction model. This silver standard corpus of more than 50 thousand sentences was automatically built based on the Comparative Toxicogenomics Database (CTD) database. We evaluated our method on the CDR test set. Results showed that our system could reach the state of the art performance with F1 of 82.44 for the DNER task and 58.90 for the CID task. Analysis demonstrated substantial benefits of both the multi-pass sieve coreference resolution method (F1 + 4.13%) and the silver CID corpus (F1 +7.3%).Database URL: SilverCID-The silver-standard corpus for CID relation extraction is freely online available at: https://zenodo.org/record/34530 (doi:10.5281/zenodo.34530). PMID:27630201

  11. Sieve-based coreference resolution enhances semi-supervised learning model for chemical-induced disease relation extraction

    PubMed Central

    Le, Hoang-Quynh; Tran, Mai-Vu; Dang, Thanh Hai; Ha, Quang-Thuy; Collier, Nigel

    2016-01-01

    The BioCreative V chemical-disease relation (CDR) track was proposed to accelerate the progress of text mining in facilitating integrative understanding of chemicals, diseases and their relations. In this article, we describe an extension of our system (namely UET-CAM) that participated in the BioCreative V CDR. The original UET-CAM system’s performance was ranked fourth among 18 participating systems by the BioCreative CDR track committee. In the Disease Named Entity Recognition and Normalization (DNER) phase, our system employed joint inference (decoding) with a perceptron-based named entity recognizer (NER) and a back-off model with Semantic Supervised Indexing and Skip-gram for named entity normalization. In the chemical-induced disease (CID) relation extraction phase, we proposed a pipeline that includes a coreference resolution module and a Support Vector Machine relation extraction model. The former module utilized a multi-pass sieve to extend entity recall. In this article, the UET-CAM system was improved by adding a ‘silver’ CID corpus to train the prediction model. This silver standard corpus of more than 50 thousand sentences was automatically built based on the Comparative Toxicogenomics Database (CTD) database. We evaluated our method on the CDR test set. Results showed that our system could reach the state of the art performance with F1 of 82.44 for the DNER task and 58.90 for the CID task. Analysis demonstrated substantial benefits of both the multi-pass sieve coreference resolution method (F1 + 4.13%) and the silver CID corpus (F1 +7.3%). Database URL: SilverCID–The silver-standard corpus for CID relation extraction is freely online available at: https://zenodo.org/record/34530 (doi:10.5281/zenodo.34530). PMID:27630201

  12. Luminescence in CaSO4 : Dy phosphor - dependence on grain agglomeration, sintering temperature, sieving and washing

    NASA Astrophysics Data System (ADS)

    Lakshmanan, A. R.; Jose, M. T.; Ponnusamy, V.; Vivek Kumar, P. R.

    2002-02-01

    In the recently developed high-sensitive CaSO4 : Dy phosphor, sieving before the high-temperature sintering treatment has successfully eliminated particle agglomeration during subsequent sintering, and has further enhanced its thermostimulated luminescence (TSL) sensitivity to γ-rays. The reduction in TSL sensitivity of higher sized grains observed earlier following the procedure of sieving after sintering has also more or less vanished. Maximum TSL sensitivity is seen after sintering around 700°C, whereas maximum photoluminescent (PL) sensitivity is seen after sintering around 325°C. While the observed increase in TSL sensitivity (by 30%) with increasing sintering temperature in the range 325-700°C is explained on the basis of diffusion of Dy3+ ions from the surface to the whole volume of the grains (0-75 µm), the drastic decrease (by a factor of 3) in PL sensitivity with increasing sintering temperature is explained on the basis of change in the Dy3+ environment on the grain surface perhaps due to oxygen incorporation. Washing with water and acetone, which affect mainly the surface traps, enhances the PL sensitivity of CaSO4 : Dy slightly; however, it does not influence TSL sensitivity very significantly. Grinding reduces PL in general, but no such trend was noticed in TSL which supports the conclusion that PL originates mainly from surface traps since grinding affects mainly the grain surface. However, the sharp reduction in TSL and PL sensitivities observed at 400°C indicates that an unusual process takes place near that sintering temperature.

  13. Determination of the feasibility of using a portable X-ray fluorescence (XRF) analyzer in the field for measurement of lead content of sieved soil.

    PubMed

    Markey, Andrea M; Clark, C Scott; Succop, Paul A; Roda, Sandra

    2008-03-01

    Soil samples collected in housing areas with potential lead contamination generally are analyzed with flame atomic absorption spectrometry (FAAS) or other laboratory methods. Previous work indicates that field-portable X-ray fluorescence (XRF) analysis is capable of detecting soil lead levels comparable to those detected by FAAS in samples sieved to less than 125 microm in a laboratory. A considerable savings, both economical and in laboratory reporting time, would occur if a practical field method could be developed that does not require laboratory digestion and analysis. The XRF method also would provide immediate results that would facilitate the provision of information to residents and other interested parties more quickly than is possible with conventional laboratory methods. The goal of the study reported here was to determine the practicality of using the field-portable XRF analyzer for analysis of lead in soil samples that were sieved in the field. The practicality of using the XRF was determined by the amount of time it took to prepare and analyze the samples in the field and by the ease with which the procedure could be accomplished on site. Another objective of the study was to determine the effects of moisture on the process of sieving the soil. Seventy-eight samples were collected from 30 locations near 10 houses and were prepared and analyzed at the locations where they were collected. Mean soil lead concentrations by XRF were 816 ppm before drying and 817 ppm after drying, and by laboratory FAAS were 1,042 ppm. Correlation of field-portable XRF and FAAS results was excellent for samples sieved to less than 125 microm, with R2 values of .9902 and .992 before and after drying, respectively. The saturation ranged from 10 percent to 90 percent. At 65 percent saturation or higher, it was not feasible to sieve the soil in the field without a thorough drying step, since the soil would not pass through the sieve. Therefore the field method with sieving was

  14. Live Imaging of Xwnt5A-ROR2 Complexes

    PubMed Central

    Rahm, Karolin; Klessing, Tina; Nienhaus, Gerd Ulrich; Wedlich, Doris; Gradl, Dietmar

    2014-01-01

    Secreted molecules of the Wnt family regulate key decisions in embryogenesis and adult tissue homeostasis by activating a complex network of Wnt signaling pathways. Although the different branches of Wnt signaling have been studied for more than 25 years, fluorophore tagged constructs for live cell imaging of Wnt molecules activating the Wnt/β-catenin pathway have become available only recently. We have generated a fluorophore tagged Wnt construct of the Xenopus Wnt5a protein (Xwnt5A) with the enhanced green fluorescent protein (EGFP), Xwnt5A-EGFP. This construct activates non-canonical Wnt pathways in an endocytosis dependent manner and is capable of compensating for the loss of endogenous Xwnt5A in Xenopus embryos. Strikingly, non-canonical Wnt pathway activation was restricted to short-range signaling while an inhibitory effect was observed in transwell cell cultures taken as long-range signaling model sytem. We used our Xwnt5A-EGFP construct to analyze in vivo binding of Wnt5A to its co-receptor ROR2 on the microscopic and on the molecular level. On the microscopic level, Xwnt5A-EGFP clusters in the membrane and recruits ROR2-mCherry to these clusters. Applying dual-colour dual-focus line-scanning fluorescence correlation spectroscopy on dorsal marginal zone explants, we identified membrane tethered Xwnt5A-EGFP molecules binding to ROR2-mCherry molecules. Our data favour a model, in which membrane-tethered Wnt-5A recruits ROR2 to form large ligand/receptor clusters and signals in an endocytosis-dependent manner. PMID:25313906

  15. Wnt5a is essential for intestinal elongation in mice

    PubMed Central

    Cervantes, Sara; Yamaguchi, Terry P.; Hebrok, Matthias

    2009-01-01

    Summary Morphogenesis of the mammalian small intestine entails extensive elongation and folding of the primitive gut into a tightly coiled digestive tube. Surprisingly, little is known about the cellular and molecular mechanisms that mediate the morphological aspects of small intestine formation. Here, we demonstrate that Wnt5a, a member of the Wnt family of secreted proteins, is essential for the development and elongation of the small intestine from the midgut region. We found that the small intestine in mice lacking Wnt5a was dramatically shortened and duplicated, forming a bifurcated lumen instead of a single tube. In addition, cell proliferation was reduced and re-intercalation of post-mitotic cells into the elongating gut tube epithelium was disrupted. Thus, our study demonstrates that Wnt5a functions as a critical regulator of midgut formation and morphogenesis in mammals. PMID:19100728

  16. Kinetic modelling of molecular hydrogen transport in microporous carbon materials.

    SciTech Connect

    Hankel, M.; Zhang, H.; Nguyen, T. X.; Bhatia, S. K.; Gray, S. K.; Smith, S. C.

    2011-01-01

    The proposal of kinetic molecular sieving of hydrogen isotopes is explored by employing statistical rate theory methods to describe the kinetics of molecular hydrogen transport in model microporous carbon structures. A Lennard-Jones atom-atom interaction potential is utilized for the description of the interactions between H{sub 2}/D{sub 2} and the carbon framework, while the requisite partition functions describing the thermal flux of molecules through the transition state are calculated quantum mechanically in view of the low temperatures involved in the proposed kinetic molecular sieving application. Predicted kinetic isotope effects for initial passage from the gas phase into the first pore mouth are consistent with expectations from previous modeling studies, namely, that at sufficiently low temperatures and for sufficiently narrow pore mouths D{sub 2} transport is dramatically favored over H{sub 2}. However, in contrast to expectations from previous modeling, the absence of any potential barrier along the minimum energy pathway from the gas phase into the first pore mouth yields a negative temperature dependence in the predicted absolute rate coefficients - implying a negative activation energy. In pursuit of the effective activation barrier, we find that the minimum potential in the cavity is significantly higher than in the pore mouth for nanotube-shaped models, throwing into question the common assumption that passage through the pore mouths should be the rate-determining step. Our results suggest a new mechanism that, depending on the size and shape of the cavity, the thermal activation barrier may lie in the cavity rather than at the pore mouth. As a consequence, design strategies for achieving quantum-mediated kinetic molecular sieving of H{sub 2}/D{sub 2} in a microporous membrane will need, at the very least, to take careful account of cavity shape and size in addition to pore-mouth size in order to ensure that the selective step, namely passage

  17. New insights for C5a and C5a receptors in sepsis

    PubMed Central

    Yan, Chunguang; Gao, Hongwei

    2012-01-01

    The complement system plays a central role in inflammation and immunity. Among the complement activation products, C5a is one of the most potent inflammatory peptides with a broad spectrum of functions. There is strong evidence for complement activation including elevated plasma level of C5a in humans and animals with sepsis. C5a exerts its effects through the C5a receptors. Of the two receptors that bind C5a, the C5aR (CD88) is known to mediate signaling activity, whereas the function of another C5a binding receptor, C5L2, remains largely unknown. Here, we review the critical role of C5a in sepsis and summarize evidence indicating that both C5aR and C5L2 act as regulating receptors for C5a during sepsis. PMID:23233853

  18. A bracket approach to improve the stability and gas sorption performance of a metal-organic framework via in situ incorporating the size-matching molecular building blocks.

    PubMed

    Chen, Di-Ming; Tian, Jia-Yue; Liu, Chun-Sen; Du, Miao

    2016-06-28

    Incorporating the in situ formed size-matching molecular building blocks (MBBs) into the open channels will remarkably improve the robustness and gas sorption performance of an evacuated metal-organic framework. As a result, such MBBs can transfer the open metal sites from the framework walls to the channel centers and separate the large channels into multiple smaller voids, leading to a molecular sieving effect and high-performance gas-separation of the modified material. PMID:27301546

  19. Molecular simulations of supercritical fluid permeation through disordered microporous carbons.

    PubMed

    Boţan, Alexandru; Vermorel, Romain; Ulm, Franz-Josef; Pellenq, Roland J-M

    2013-08-13

    Fluid transport through microporous carbon-based materials is inherent in numerous applications, ranging from gas separation by carbon molecular sieves to natural gas production from coal seams and gas shales. The present study investigates the steady-state permeation of supercritical methane in response to a constant cross-membrane pressure drop. We performed dual control volume grand canonical molecular dynamics (DCV-GCMD) simulations to mimic the conditions of actual permeation experiments. To overcome arbitrary assumptions regarding the investigated porous structures, the membranes were modeled after the CS1000a and CS1000 molecular models, which are representative of real microporous carbon materials. When adsorption-induced molecular trapping (AIMT) mechanisms are negligible, we show that the permeability of the microporous material, although not significantly sensitive to the pressure gradient, monotonically decreases with temperature and reservoir pressures, consistent with diffusion theory. However, when AIMT occurs, the permeability increases with temperature in agreement with experimental data found in the literature. PMID:23886335

  20. A New Application of the Electrical Penetration Graph (EPG) for Acquiring and Measuring Electrical Signals in Phloem Sieve Elements.

    PubMed

    Salvador-Recatalà, Vicenta; Tjallingii, W Freddy

    2015-07-02

    Electrophysiological properties of cells are often studied in vitro, after dissociating them from their native environments. However, the study of electrical transmission between distant cells in an organism requires in vivo, artifact-free recordings of cells embedded within their native environment. The transmission of electrical signals from wounded to unwounded areas in a plant has since long piqued the interest of botanists. The phloem, the living part of the plant vasculature that is spread throughout the plant, has been postulated as a major tissue in electrical transmission in plants. The lack of suitable electrophysiological methods poses many challenges for the study of the electrical properties of the phloem cells in vivo. Here we present a novel approach for intracellular electrophysiology of sieve elements (SEs) that uses living aphids, or other phloem-feeding hemipteran insects, integrated in the electrical penetration graph (EPG) circuit. The versatility, robustness, and accuracy of this method made it possible to record and study in detail the wound-induced electrical signals in SEs of central veins of the model plant Arabidopsis thaliana(1). Here we show that EPG-electrodes can be easily implemented for intracellular electrophysiological recordings of SEs in marginal veins, as well as to study the capacity of SEs to respond with electrical signals to several external stimuli. The EPG approach applied to intracellular electrophysiology of SEs can be implemented to a wide variety of plant species, in a large number of plant/insect combinations, and for many research aims.

  1. Comparison between a spray column and a sieve tray column operating as liquid-liquid heat exchangers

    SciTech Connect

    Keller, A.; Jacobs, H.R.; Boehm, R.F.

    1980-12-01

    The performance of a spray column and a sieve tray column was compared as a liquid-liquid heat exchanger. In carrying out these studies a 15.2 cm (6.0 in.) diameter column, 183 cm (6.0 ft) tall was utilized. The performance of the spray column as a heat exchanger was shown to correlate with the model of Letan-Kehat which has as a basis that the heat transfer is dominated by the wakeshedding characteristics of the drops over much of the column length. This model defines several hydrodynamic zones along the column of which the wake formation zone at the bottom appears to have the most efficient heat transfer. The column was also operated with four perforated plates spaced two column diameters apart in order to take advantage of the wake formation zone heat transfer. The plates induce coalescence of the dispersed phase and reformation of the drops, and thus cause a repetition of the wake formation zone. It is shown that the overall volumetric heat transfer coefficient in a perforated plate column is increased by a minimum of eleven percent over that in a spray column. A hydrodynamic model that predicts the performance of a perforated plate column is suggested.

  2. Zeolite 5A Catalyzed Etherification of Diphenylmethanol

    ERIC Educational Resources Information Center

    Cooke, Jason; Henderson, Eric J.; Lightbody, Owen C.

    2009-01-01

    An experiment for the synthetic undergraduate laboratory is described in which zeolite 5A catalyzes the room temperature dehydration of diphenylmethanol, (C[subscript 6]H[subscript 5])[subscript 2]CHOH, producing 1,1,1',1'-tetraphenyldimethyl ether, (C[subscript 6]H[subscript 5])[subscript 2]CHOCH(C[subscript 6]H[subscript 5])[subscript 2]. The…

  3. [In situ diffuse reflectance FTIR spectroscopy study of CO adsorption on Ni2P/mesoporous molecule sieve catalysts].

    PubMed

    Liu, Qian-qian; Ji, Sheng-fu; Wu, Ping-yi; Hu, Lin-hua; Huang, Xiao-fan; Zhu, Ji-qin; Li, Cheng-yue

    2009-05-01

    Abstract The supported nickel phosphate precursors were prepared by incipient wetness impregnation using nickel nitrate as nickel source, diammonium hydrogen phosphate as phosphorus source, and MCM-41, MCM-48, SBA-15 and SBA-16 as supports, respectively. Then, the supported Ni2 P catalysts were prepared by temperature-programmed reduction in flowing Hz from their nickel phosphate precursors. The in situ diffuse reflectance FTIR spectroscopy (DRIFTS) analysis with the probe molecule CO was carried out to characterize the surface properties. The results indicated that there were significant differences in the spectral features of the samples. The upsilon(CO) absorbances observed for adsorbed CO on mesoporous molecule sieve was attributed to weak physical adsorption. There are four different kinds of upsilon(CO) absorbances observed for adsorbed CO on Ni2 P/MCM-41 catalyst with the following assignments: (1) the formation of Ni(CO)4 at 2055 cm(-1). (2) CO terminally bonded to cus Ni(delta+) (0

  4. Comparative analysis of the digestibility of sewage fine sieved fraction and hygiene paper produced from virgin fibers and recycled fibers.

    PubMed

    Ghasimi, Dara S M; Zandvoort, Marcel H; Adriaanse, Michiel; van Lier, Jules B; de Kreuk, Merle

    2016-07-01

    Sewage fine sieved fraction (FSF) is a heterogeneous substrate consisting of mainly toilet paper fibers sequestered from municipal raw sewage by a fine screen. In earlier studies, a maximum biodegradation of 62% and 57% of the sewage FSF was found under thermophilic (55°C) and mesophilic (35°C) conditions, respectively. In order to research this limited biodegradability of sewage FSF, this study investigates the biodegradation of different types of cellulosic fibers-based hygiene papers including virgin fibers based toilet paper (VTP), recycled fiber based toilet paper (RTP), virgin pulp for paper production (VPPP) as a raw material, as well as microcrystalline cellulose (MCC) as a kind of fiberless reference material. The anaerobic biodegradation or digestibility tests were conducted under thermophilic and mesophilic conditions. Results of the experiments showed different biomethane potential (BMP) values for each tested cellulose fiber-based substrate, which might be associated with the physical characteristics of the fibers, type of pulping, presence of lignin encrusted fibers, and/or the presence of additive chemicals and refractory compounds. Higher hydrolysis rates (Kh), higher specific methane production rates (SMPR) and shorter required incubation times to achieve 90% of the BMP (t90%CH4), were achieved under thermophilic conditions for all examined substrates compared to the mesophilic ones. Furthermore, the biodegradability of all employed cellulose fiber-based substrates was in the same range, 38-45%, under both conditions and less than the observed FSF biodegradability, i.e. 57-62%. MCC achieved the highest BMP and biodegradability, 86-91%, among all cellulosic substrates. PMID:27172811

  5. 5 A, version modifée

    PubMed Central

    Vallis, Michael; Piccinini-Vallis, Helena; Sharma, Arya M.; Freedhoff, Yoni

    2013-01-01

    Objectif Adapter le modèle 5 A pour offrir aux professionnels des soins primaires un cadre de counseling sur l'obésité. Sources des données Une recension systématique des ouvrages spécialisés a été effectuée dans MEDLINE à l'aide des expressions de recherche 5 A's (49 articles recensés, tous pertinents) et 5 A's et primary care (8 articles recensés, tous redondants). On a aussi fait une recherche dans les sites web du National Institute of Health et de l'Organisation mondiale de la Santé. Message principal L'approche 5 A (autorisation, analyse, avis, accord et aide ou ask, assess, advise, agree et assist en anglais), élaborée pour la cessation du tabagisme, peut être adaptée au counseling sur l'obésité. Demander l'autorisation de discuter du poids; ne pas porter de jugement et explorer la volonté du patient de changer. Analyser l'indice de masse corporelle, la circonférence de la taille et le stade de l'obésité; explorer les déclencheurs et les complications de l'excès de poids. Donner son avis sur les risques de l'obésité pour la santé, les bienfaits d'une modeste perte de poids, la nécessité d'une stratégie à long terme et les options de traitements. Se mettre d'accord sur des attentes, des objectifs et des changements comportementaux réalistes pour perdre du poids et sur les détails précis du plan de traitement. Assister dans l'identifcation et l'atténuation des obstacles; offrir des ressources, aider à trouver et à consulter les services appropriés et organiser un suivi périodique. Conclusion Les 5 A représentent une stratégie d'intervention comportementale fondée sur des données probantes qui a le potentiel d'améliorer le taux de réussite de la gestion du poids en soins primaires.

  6. 1,2,4-Triazolo[1,5-a]quinoxaline as a versatile tool for the design of selective human A3 adenosine receptor antagonists: synthesis, biological evaluation, and molecular modeling studies of 2-(hetero)aryl- and 2-carboxy-substituted derivatives.

    PubMed

    Catarzi, Daniela; Colotta, Vittoria; Varano, Flavia; Lenzi, Ombretta; Filacchioni, Guido; Trincavelli, Letizia; Martini, Claudia; Montopoli, Christian; Moro, Stefano

    2005-12-15

    A number of 4-oxo-substituted 1,2,4-triazolo[1,5-a]quinoxaline derivatives bearing at position-2 the claimed (hetero)aryl moiety (compounds 1-15) but also a carboxylate group (16-28, 32-36) or a hydrogen atom (29-31) were designed as human A3 (hA3) adenosine receptor (AR) antagonists. This study produced some interesting compounds and among them the 2-(4-methoxyphenyl)-1,2,4-triazolo[1,5-a]quinoxalin-4-one (8), which can be considered one of the most potent and selective hA3 adenosine receptor antagonists reported till now. Moreover, as a new finding, replacement of the classical 2-(hetero)aryl moiety with a 2-carboxylate function (compounds 16-28 and 32-36) maintained good hA3 AR binding activity but, most importantly and interestingly, produced a large increase in hA3 versus hA1 selectivity. A receptor-based SAR analysis provided new interesting insights about the steric and electrostatic requirements that are important for the anchoring of these derivatives at the hA3 receptor recognition site, thus highlighting the versatility of the triazoloquinoxaline scaffold for obtaining potent and selective hA3 AR antagonists.

  7. Sieve Estimation of Constant and Time-Varying Coefficients in Nonlinear Ordinary Differential Equation Models by Considering Both Numerical Error and Measurement Error

    PubMed Central

    Xue, Hongqi; Miao, Hongyu; Wu, Hulin

    2010-01-01

    This article considers estimation of constant and time-varying coefficients in nonlinear ordinary differential equation (ODE) models where analytic closed-form solutions are not available. The numerical solution-based nonlinear least squares (NLS) estimator is investigated in this study. A numerical algorithm such as the Runge–Kutta method is used to approximate the ODE solution. The asymptotic properties are established for the proposed estimators considering both numerical error and measurement error. The B-spline is used to approximate the time-varying coefficients, and the corresponding asymptotic theories in this case are investigated under the framework of the sieve approach. Our results show that if the maximum step size of the p-order numerical algorithm goes to zero at a rate faster than n−1/(p∧4), the numerical error is negligible compared to the measurement error. This result provides a theoretical guidance in selection of the step size for numerical evaluations of ODEs. Moreover, we have shown that the numerical solution-based NLS estimator and the sieve NLS estimator are strongly consistent. The sieve estimator of constant parameters is asymptotically normal with the same asymptotic co-variance as that of the case where the true ODE solution is exactly known, while the estimator of the time-varying parameter has the optimal convergence rate under some regularity conditions. The theoretical results are also developed for the case when the step size of the ODE numerical solver does not go to zero fast enough or the numerical error is comparable to the measurement error. We illustrate our approach with both simulation studies and clinical data on HIV viral dynamics. PMID:21132064

  8. Batteries: Sieving the ions

    NASA Astrophysics Data System (ADS)

    Serre, Christian

    2016-07-01

    The major obstacle in the development of Li–S batteries is the undesired dissolution of polysulfide intermediates produced during electrochemical reactions. Now, a metal–organic framework-based separator is shown to mitigate the problem, leading to stable long cycles.

  9. Generalized Fibonacci photon sieves

    NASA Astrophysics Data System (ADS)

    Ke, Jie; Zhang, Junyong

    2015-08-01

    We propose a family of zone plates which are produced by the generalized Fibonacci sequences and their axial focusing properties are analyzed in detail. Compared with traditional Fresnel zone plates, the generalized Fibonacci zone plates present two axial foci with equal intensity. Besides, we propose an approach to adjust the axial locations of the two foci by means of different optical path difference, and further give the deterministic ratio of the two focal distances which attributes to their own generalized Fibonacci sequences. The generalized Fibonacci zone plates may allow for new applications in micro and nanophotonics.

  10. Cystathionine-Gamma-Lyase Gene Deletion Protects Mice against Inflammation and Liver Sieve Injury following Polymicrobial Sepsis

    PubMed Central

    Gaddam, Ravinder Reddy; Fraser, Robin; Badiei, Alireza; Chambers, Stephen; Cogger, Victoria C; Le Couteur, David G; Ishii, Isao; Bhatia, Madhav

    2016-01-01

    Background Hydrogen sulfide (H2S), produced by the activity of cystathionine-gamma-lyase (CSE), is a key mediator of inflammation in sepsis. The liver sinusoidal endothelial cells (LSECs) are important target and mediator of sepsis. The aim of this study was to investigate the role of CSE-derived H2S on inflammation and LSECs fenestrae in caecal-ligation and puncture (CLP)-induced sepsis using CSE KO mice. Methods Sepsis was induced by CLP, and mice (C57BL/6J, male) were sacrificed after 8 hours. Liver, lung, and blood were collected and processed to measure CSE expression, H2S synthesis, MPO activity, NF-κB p65, ERK1/2, and cytokines/chemokines levels. Diameter, frequency, porosity and gap area of the liver sieve were calculated from scanning electron micrographs of the LSECs. Results An increased CSE expression and H2S synthesizing activity in the liver and lung of wild-type mice following CLP-induced sepsis. This was associated with an increased liver and lung MPO activity, and increased liver and lung and plasma levels of the pro-inflammatory cytokines TNF-α, IL-6, and IL-1β, and the chemokines MCP-1 and MIP-2α. Conversely, CSE KO mice had less liver and lung injury and reduced inflammation following CLP-induced sepsis as evidenced by decreased levels of H2S synthesizing activity, MPO activity, and pro-inflammatory cytokines/chemokines production. Extracellular-regulated kinase (ERK1/2) and nuclear factor-κB p65 (NF-κB) became significantly activated after the CLP in WT mice but not in CSE KO mice. In addition, CLP-induced damage to the LSECs, as indicated by increased defenestration and gaps formation in the LSECs compared to WT sham control. CSE KO mice showed decreased defenestration and gaps formation following sepsis. Conclusions Mice with CSE (an H2S synthesising enzyme) gene deletion are less susceptible to CLP-induced sepsis and associated inflammatory response through ERK1/2-NF-κB p65 pathway as evidenced by reduced inflammation, tissue damage

  11. A new sieving matrix for DNA sequencing, genotyping and mutation detection and high-throughput genotyping with a 96-capillary array system

    SciTech Connect

    Gao, David

    1999-11-08

    Capillary electrophoresis has been widely accepted as a fast separation technique in DNA analysis. In this dissertation, a new sieving matrix is described for DNA analysis, especially DNA sequencing, genetic typing and mutation detection. A high-throughput 96 capillary array electrophoresis system was also demonstrated for simultaneous multiple genotyping. The authors first evaluated the influence of different capillary coatings on the performance of DNA sequencing. A bare capillary was compared with a DB-wax, an FC-coated and a polyvinylpyrrolidone dynamically coated capillary with PEO as sieving matrix. It was found that covalently-coated capillaries had no better performance than bare capillaries while PVP coating provided excellent and reproducible results. The authors also developed a new sieving Matrix for DNA separation based on commercially available poly(vinylpyrrolidone) (PVP). This sieving matrix has a very low viscosity and an excellent self-coating effect. Successful separations were achieved in uncoated capillaries. Sequencing of M13mp18 showed good resolution up to 500 bases in treated PVP solution. Temperature gradient capillary electrophoresis and PVP solution was applied to mutation detection. A heteroduplex sample and a homoduplex reference were injected during a pair of continuous runs. A temperature gradient of 10 C with a ramp of 0.7 C/min was swept throughout the capillary. Detection was accomplished by laser induced fluorescence detection. Mutation detection was performed by comparing the pattern changes between the homoduplex and the heteroduplex samples. High throughput, high detection rate and easy operation were achieved in this system. They further demonstrated fast and reliable genotyping based on CTTv STR system by multiple-capillary array electrophoresis. The PCR products from individuals were mixed with pooled allelic ladder as an absolute standard and coinjected with a 96-vial tray. Simultaneous one-color laser-induced fluorescence

  12. Tomato ovary-to-fruit transition is characterized by a spatial shift of mRNAs for cell wall invertase and its inhibitor with the encoded proteins localized to sieve elements.

    PubMed

    Palmer, William M; Ru, Lei; Jin, Ye; Patrick, John W; Ruan, Yong-Ling

    2015-02-01

    Central to understanding fruit development is to elucidate the processes mediating a successful transition from pre-pollination ovaries to newly set fruit, a key step in establishing fruit yield potential. In tomato, cell wall invertase (CWIN) LIN5 and its inhibitor INH1 are essential for fruit growth. However, the molecular and cellular basis by which they exert their roles in ovary-to-fruit transition remains unknown. To address this issue, we conducted a study focusing on ovaries and fruitlets at 2 days before and 2 days after anthesis, respectively. In situ hybridization analyses revealed that LIN5 and INH1 exhibited a dispersed expression in ovaries compared with their phloem-specific expression in fruitlets. Remarkably, LIN5 and INH1 proteins were immunologically co-localized to cell walls of sieve elements (SEs) in ovaries immediately prior to anthesis and in young fruitlets, but were undetectable in provascular bundles of younger ovaries. A burst in CWIN activity occurred during ovary-to-fruit transition. Interestingly, the ovaries, but not the fruitlets, exhibited high expression of a defective invertase, SldeCWIN1, an ortholog of which is known to enhance inhibition of INH on CWIN activity in tobacco. Imaging of a fluorescent symplasmic tracer indicated an apoplasmic phloem unloading pathway operated in ovaries, contrary to the previously observed symplasmic unloading pathway in fruit pericarp. These new data indicate that (1) a phloem-specific patterning of the CWIN and INH mRNAs is induced during ovary-to-fruit transition, and (2) LIN5 protein functions specifically in walls of SEs and increases its activity during ovary-to-fruit transition, probably to facilitate phloem unloading and to generate a glucose signal positively regulating cell division, hence fruit set. PMID:25680776

  13. Classical swine fever virus NS5B protein suppresses the inhibitory effect of NS5A on viral translation by binding to NS5A.

    PubMed

    Sheng, Chun; Wang, Jing; Xiao, Jing; Xiao, Jun; Chen, Yan; Jia, Lin; Zhi, Yimiao; Li, Guangyuan; Xiao, Ming

    2012-05-01

    In order to investigate molecular mechanisms of internal ribosome entry site (IRES)-mediated translation in classical swine fever virus (CSFV), an important pathogen of pigs, the expression level of NS3 was evaluated in the context of genomic RNAs and reporter RNA fragments. All data showed that the NS5A protein has an inhibitory effect on IRES-mediated translation and that NS5B proteins suppress the inhibitory effect of NS5A on viral translation, but CSFV NS5B GDD mutants do not. Furthermore, glutathione S-transferase pull-down assay and immunoprecipitation analysis, associated with deletion and alanine-scanning mutations, were performed. Results showed that NS5B interacts with NS5A and that the region aa 390-414, located in the C-terminal half of NS5A, is important for binding of NS5B to NS5A. Furthermore, amino acids K399, T401, E406 and L413 in the region were found to be essential for NS5A-NS5B interaction, virus rescue and infection. The above-mentioned region and four amino acids were observed to overlap with the site responsible for inhibition of IRES-mediated translation by the NS5A protein. We also found that aa 63-72, aa 637-653 and the GDD motif of NS5B were necessary for the interaction between NS5A and NS5B. These findings suggest that the repression activity of the NS5B protein toward the role of NS5A in translation might be achieved by NS5A-NS5B interaction, for which aa 390-414 of NS5A and aa 63-72, aa 637-653 and the GDD motif of NS5B are indispensable. This is important for understanding the role of NS5A-NS5B interaction in the virus life cycle. PMID:22258858

  14. FRS 1000, an extract of red onion peel, strongly inhibits phosphodiesterase 5A (PDE 5A).

    PubMed

    Lines, T C; Ono, M

    2006-03-01

    As part of our ongoing search for flavonoids that are bioactive in humans, it was determined that FRS 1000, a beverage containing flavonoids extracted from onion peel, showed unexpected improvement of male sexual function. An in vitro enzyme assay clearly showed that FRS 1000 has a strong phosphodiesterase 5A (PDE 5A) inhibitory activity, which is considered to be important for treatment of erectile dysfunction. Detailed assays of each major ingredient indicated that the antioxidative flavonoid quercetin was responsible for the activity. Results also suggested that PDE 5A inhibition is not directly related to the free radical scavenging activity of flavonoids. PMID:16492525

  15. Determination of the acid/base properties of MgY and NH4Y molecular sieves by inverse gas chromatography.

    PubMed

    Bilgiç, Ceyda; Tümsek, Fatma

    2007-08-24

    The surface characterization of MgY and NH(4)Y zeolites was performed using inverse gas chromatography (IGC). The adsorption thermodynamic parameters (the standard enthalpy (DeltaH degrees ), standard entropy change (DeltaS degrees ), and free energy change of adsorption (DeltaG degrees ), the dispersive component of the surface free energies (gamma(S)(d)), and the acid-base character of the surface of MgY and NH(4)Y zeolites were estimated using the retention time of different non-polar and polar probes at infinite dilution region. The specific free energy of adsorption (DeltaG(sp)), the specific enthalpy of adsorption (DeltaH(sp)), and the specific entropy of adsorption (DeltaS(sp)) of polar probes on MgY and NH(4)Y zeolites were determined. The values of the DeltaH(sp) were correlated with both the donor and acceptor numbers of the probes to quantify the acidic K(A) and the basic K(D) parameters of the zeolite surfaces. The values obtained for the K(A) and K(D) parameters indicated a basic character for the surface of MgY and NH(4)Y zeolites. PMID:17451721

  16. Manganese oxide octahedral molecular sieve K-OMS-2 as catalyst in post plasma-catalysis for trichloroethylene degradation in humid air.

    PubMed

    Nguyen Dinh, M T; Giraudon, J-M; Vandenbroucke, A M; Morent, R; De Geyter, N; Lamonier, J-F

    2016-08-15

    The total oxidation of trichloroethylene (TCE) in air at low relative humidity (RH=10%) in the presence of CO2 (520ppmv) was investigated in function of energy density using an atmospheric pressure negative DC luminescent glow discharge combined with a cryptomelane catalyst positioned downstream of the plasma reactor at a temperature of 150°C. When using Non-Thermal Plasma (NTP) alone, it is found a low COx (x=1-2) yield in agreement with the detection of gaseous polychlorinated by-products in the outlet stream as well as ozone which is an harmful pollutant. Introduction of cryptomelane enhanced trichloroethylene removal, totally inhibited plasma ozone formation and increased significantly the COx yield. The improved performances of the hybrid system were mainly ascribed to the total destruction of plasma generated ozone on cryptomelane surface to produce active oxygen species. Consequently these active oxygen species greatly enhanced the abatement of the plasma non-reacted TCE and completely destroyed the hazardous plasma generated polychlorinated intermediates. The facile redox of Mn species associated with oxygen vacancies and mobility as well as the textural properties of the catalyst might also contribute as a whole to the efficiency of the process. PMID:27107238

  17. Preparation and characterization of L-Leucine-modified amphiprotic bifunctional mesoporous SBA-15 molecular sieve as a drug carrier for ribavirin

    NASA Astrophysics Data System (ADS)

    Xu, Zhigang; Ji, Yongsheng; Guan, Min; Huang, Huayu; Zhao, Chuande; Zhang, Haixia

    2010-03-01

    In this study, an amphiphilic bifunctional mesoporous SBA-15 material (AMPBIF-SBA-15) was synthesized through post-synthesis method as a drug carrier. Ribavirin was selected as the model drug and whose release from both unmodified and functionalized SBA-15 was evaluated in four media solutions with different pH or ionic strength. The release process indicated that AMPBIF-SBA-15 was a pH-sensitive drug carrier, which showed a phased low-release effect to ribavirin in the simulated body fluid (PBS, pH 7.4) solution. The materials were further characterized by Fourier transform infrared (FTIR) spectroscopy, powder X-ray diffraction (XRD), transmission electron microscopy (TEM), nitrogen adsorption-desorption measurements and elemental analysis. This study provided a novel drug carrier for ribavirin to improve curative effect of ribavirin.

  18. Carbogenic molecular sieves for reaction and separation by design: A novel approach to shape selective super base, super acid and catalytic membranes. Final report

    SciTech Connect

    Foley, Henry C.

    2002-03-18

    This report details the findings of three years of research plus one year of a no-cost extension. Primary results are the work with supported nanoporous carbon membranes for separation and reaction as well as with cesium-nanoporous carbon catalysts. The work resulted in 17 plus 2 papers (2 are in progress) and partial or full support for five Ph.D. students. Two patents were filed based on this research.

  19. A SIEVE M-THEOREM FOR BUNDLED PARAMETERS IN SEMIPARAMETRIC MODELS, WITH APPLICATION TO THE EFFICIENT ESTIMATION IN A LINEAR MODEL FOR CENSORED DATA*

    PubMed Central

    Ding, Ying; Nan, Bin

    2013-01-01

    In many semiparametric models that are parameterized by two types of parameters – a Euclidean parameter of interest and an infinite-dimensional nuisance parameter, the two parameters are bundled together, i.e., the nuisance parameter is an unknown function that contains the parameter of interest as part of its argument. For example, in a linear regression model for censored survival data, the unspecified error distribution function involves the regression coefficients. Motivated by developing an efficient estimating method for the regression parameters, we propose a general sieve M-theorem for bundled parameters and apply the theorem to deriving the asymptotic theory for the sieve maximum likelihood estimation in the linear regression model for censored survival data. The numerical implementation of the proposed estimating method can be achieved through the conventional gradient-based search algorithms such as the Newton-Raphson algorithm. We show that the proposed estimator is consistent and asymptotically normal and achieves the semiparametric efficiency bound. Simulation studies demonstrate that the proposed method performs well in practical settings and yields more efficient estimates than existing estimating equation based methods. Illustration with a real data example is also provided. PMID:24436500

  20. Symplasmic Constriction and Ultrastructural Features of the Sieve Element/Companion Cell Complex in the Transport Phloem of Apoplasmically and Symplasmically Phloem-Loading Species1

    PubMed Central

    Kempers, Ronald; Ammerlaan, Ankie; van Bel, Aart J.E.

    1998-01-01

    The ultrastructural features of the sieve element/companion cell complexes were screened in the stem phloem of two symplasmically loading (squash, [Cucurbita maxima L.] and Lythrum salicaria L.) and two apoplasmically loading (broad bean [Vicia faba L.] and Zinnia elegans L.) species. The distinct ultrastructural differences between the companion cells in the collection phloem of symplasmically and apoplasmically phloem-loading species continue to exist in the transport phloem. Plasmodesmograms of the stem phloem showed a universal symplasmic constriction at the interface between the sieve element/companion cell complex and the phloem parenchyma cells. This contrasts with the huge variation in symplasmic continuity between companion cells and adjoining cells in the collection phloem of symplasmically and apoplasmically loading species. Further, the ultrastructure of the companion cells in the transport phloem faintly reflected the features of the companion cells in the loading zone of the transport phloem. The companion cells of squash contained numerous small vacuoles (or vesicles), and those of L. salicaria contained a limited number of vacuoles. The companion cells of broad bean and Z. elegans possessed small wall protrusions. Implications of the present findings for carbohydrate processing in intact plants are discussed.

  1. 17 CFR 259.5a - Form U5A, for notification of registration filed under section 5(a) of the Act.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ...: For Federal Register citations affecting Form U5A, see the List of CFR Sections Affected, which... 17 Commodity and Securities Exchanges 3 2010-04-01 2010-04-01 false Form U5A, for notification of... OF 1935 Forms for Registration and Annual Supplements § 259.5a Form U5A, for notification...

  2. Removal of digesta components from the rumen of steers determined by sieving techniques and fluid, particulate and microbial markers.

    PubMed

    Dixon, R M; Milligan, L P

    1985-03-01

    When 103Ru-labelled Tris (1,10-phenanthroline) ruthenium II chloride (103Ru-P) particulate marker in aqueous solution was added to the rumen of four steers given 5.5 kg grass hay/d at two-hourly intervals, the distribution of 103Ru-P marker among rumen particles of various sizes was the same at 4 h, 3 d and 7 d after administration, the concentration of 103Ru-P/g dry matter (DM) was inversely related to particle size and 0.30 of the 103Ru-P was associated with the DM of particles too large to be moved from the rumen at a meaningful rate. Thus, fractional outflow rate (FOR) of 103Ru-P would reflect, but was not a direct measure of, the FOR of the small particle pool in the rumen. When rumen digesta were labelled with 103Ru-P, placed in nylon cloth bags and incubated in vitro with unlabelled digesta, 59% of the 103Ru-P disappeared from the nylon bag in 24 h, and 74% in 48 h. Similar results were obtained when large particles (retained by a 3.2 mm mesh screen during wet sieving) from rumen digesta were subjected to this procedure. In a further experiment, the steers were given the hay in either the long or ground form and drinking water to which 10 g sodium chloride/l were, or were not, added. The FOR of 51CrEDTA in centrifuged rumen fluid was increased (P less than 0.05) from 1.78 to 2.10/d by grinding of the hay diet, but was not influenced by the intake of an additional 257 g NaCl/d. The FOR values of 103Ru-P in mixed rumen digesta and organic 35S in micro-organisms were linearly correlated (P less than 0.05) and were not affected (P greater than 0.05) by grinding and salt treatments. On average, the FOR of organic 35S in micro-organisms was 0.41 of that of 51CrEDTA in centrifuged rumen fluid and 0.85 of that of 103Ru-P in rumen digesta respectively. Grinding of the hay did not (P greater than 0.05) change the proportion of rumen DM (0.476-0.515) or faecal DM (0.107-0.153) retained by the 3.2 mm mesh and larger screens. FOR from the rumen of a given size group of

  3. Permeance of H2 through porous graphene from molecular dynamics

    NASA Astrophysics Data System (ADS)

    Liu, Hongjun; Dai, Sheng; Jiang, De-en

    2013-12-01

    A recent experiment (Koenig et al., 2012 [15]) demonstrated the capability of porous graphene as one-atom-thin membrane to separate gases by molecular sieving. A quantitative connection between the measured leak rate and the simulated gas permeance has yet to be established. Using H2 as a model gas, here we determine its permeance through porous graphene from molecular dynamics (MD) simulations. Trajectories are used to directly obtain H2 flux, pressure drop across the graphene membrane, and subsequently, H2 permeance. The permeance is determined to be on the order of 105 GPU (gas permeance unit) for pressure driving forces ranging from 2 to 163 atm. By relating to the experimental leak rate, we then use the permeation data to estimate the pore density in the experimentally created porous graphene.

  4. Magnetismo Molecular (Molecular Magentism)

    SciTech Connect

    Reis, Mario S; Moreira Dos Santos, Antonio F

    2010-07-01

    The new synthesis processes in chemistry open a new world of research, new and surprising materials never before found in nature can now be synthesized and, as a wonderful result, observed a series of physical phenomena never before imagined. Among these are many new materials the molecular magnets, the subject of this book and magnetic properties that are often reflections of the quantum behavior of these materials. Aside from the wonderful experience of exploring something new, the theoretical models that describe the behavior these magnetic materials are, in most cases, soluble analytically, which allows us to know in detail the physical mechanisms governing these materials. Still, the academic interest in parallel this subject, these materials have a number of properties that are promising to be used in technological devices, such as in computers quantum magnetic recording, magnetocaloric effect, spintronics and many other devices. This volume will journey through the world of molecular magnets, from the structural description of these materials to state of the art research.

  5. Solar, planetary, and other inert gases in two sieve fractions of a disaggregated Allende sample - A study by stepwise heating extraction

    NASA Technical Reports Server (NTRS)

    Palma, R. L.; Heymann, D.

    1988-01-01

    Inert gases released by stepwise heating of unaltered, strongly magnetic, and weakly magnetic samples from the 0-64 micron and the 105-250 micron fractions of a disaggregated and sieved sample of the Allende meteorite reveal the occurrence of both solar and planetary neon. The origin of the solar neon is thought to be implantation of solar wind ions. The origin of the planetary neon remains unresolved. Heavy isotope enriched components of krypton and xenon have been detected and there are some indications that a light krypton component may also be present. Other than a larger concentration of Xe-129 in the weakly magnetic samples, the signatures of the magnetic separates are isotopically very similar.

  6. Highly selective quantum sieving of D2 from H2 by a metal-organic framework as determined by gas manometry and infrared spectroscopy.

    PubMed

    FitzGerald, Stephen A; Pierce, Christopher J; Rowsell, Jesse L C; Bloch, Eric D; Mason, Jarad A

    2013-06-26

    The quantum sieving effect between D2 and H2 is examined for a series of metal-organic frameworks (MOFs) over the temperature range 77-150 K. Isothermal adsorption measurements demonstrate a consistently larger isosteric heat of adsorption for D2 vs H2, with the largest difference being 1.4 kJ/mol in the case of Ni-MOF-74. This leads to a low-pressure selectivity for this material that increases from 1.5 at 150 K to 5.0 at 77 K. Idealized adsorption solution theory indicates that the selectivity decreases with increasing pressure, but remains well above unity at ambient pressure. Infrared measurements on different MOF materials show a strong correlation between selectivity and the frequency of the adsorbed H2 translational band. This confirms that the separation is predominantly due to the difference in the zero-point energies of the adsorbed isotopologues.

  7. Molecular Plasmonics.

    PubMed

    Wilson, Andrew J; Willets, Katherine A

    2016-06-12

    In this review, we survey recent advances in the field of molecular plasmonics beyond the traditional sensing modality. Molecular plasmonics is explored in the context of the complex interaction between plasmon resonances and molecules and the ability of molecules to support plasmons self-consistently. First, spectroscopic changes induced by the interaction between molecular and plasmonic resonances are discussed, followed by examples of how tuning molecular properties leads to active molecular plasmonic systems. Next, the role of the position and polarizability of a molecular adsorbate on surface-enhanced Raman scattering signals is examined experimentally and theoretically. Finally, we introduce recent research focused on using molecules as plasmonic materials. Each of these examples is intended to highlight the role of molecules as integral components in coupled molecule-plasmon systems, as well as to show the diversity of applications in molecular plasmonics.

  8. Molecular Plasmonics

    NASA Astrophysics Data System (ADS)

    Wilson, Andrew J.; Willets, Katherine A.

    2016-06-01

    In this review, we survey recent advances in the field of molecular plasmonics beyond the traditional sensing modality. Molecular plasmonics is explored in the context of the complex interaction between plasmon resonances and molecules and the ability of molecules to support plasmons self-consistently. First, spectroscopic changes induced by the interaction between molecular and plasmonic resonances are discussed, followed by examples of how tuning molecular properties leads to active molecular plasmonic systems. Next, the role of the position and polarizability of a molecular adsorbate on surface-enhanced Raman scattering signals is examined experimentally and theoretically. Finally, we introduce recent research focused on using molecules as plasmonic materials. Each of these examples is intended to highlight the role of molecules as integral components in coupled molecule-plasmon systems, as well as to show the diversity of applications in molecular plasmonics.

  9. Gastric emptying and sieving of solid food and pancreatic and biliary secretions after solid meals in patients with nonresective ulcer surgery

    SciTech Connect

    Mayer, E.A.; Thomson, J.B.; Jehn, D.; Reedy, T.; Elashoff, J.; Deveny, C.; Meyer, J.H.

    1984-12-01

    This study was undertaken to compare with previously published findings in normal subjects and subjects after truncal vagotomy and antrectomy the effects of nonresective ulcer surgery on (a) gastric emptying, grinding, and sieving of solid food and on (b) pancreatic and biliary secretions. Six subjects with proximal gastric vagotomy and 7 subjects with truncal vagotomy with pyloroplasty were studied using a previously validated indicator perfusion system with its aspiration port placed in the proximal jejunum. All subjects were given a meal of 30 g of /sup 99m/Tc-liver, 60 g of beefsteak, and 100 ml of H/sub 2/O. In conjunction with a gamma-camera to measure total gastric emptying of /sup 99m/Tc-liver, this method allowed the estimation of the fraction of 99mTc-liver emptied from the stomach as particles of less than 1-mm diameter; in addition, it was possible to measure jejunal concentrations and outputs of bile salts and pancreatic enzymes. In subjects with proximal gastric vagotomy, all parameters studied were indistinguishable from normal. Subjects with truncal vagotomy and pyloroplasty behaved similarly to subjects with vagotomy and antrectomy, showing (a) early precipitous emptying of food, (b) heterogeneous distribution of half-emptying times, (c) near normal concentration of biliary and pancreatic secretions, (d) markedly reduced jejunal flow rates, and (e) a reduction in postcibal trypsin secretion. In contrast to subjects after truncal vagotomy and antrectomy, however, the majority of subjects with vagotomy and pyloroplasty did not show a persistent defect in grinding and sieving of solid food.

  10. Molecular beacons.

    PubMed

    Tan, Weihong; Wang, Kemim; Drake, Timothy J

    2004-10-01

    This opinion covers the field of molecular beacons (MBs), in which nucleic acids are molecularly engineered to have unique functions for the investigation of biomolecules. Molecular beacons have been used in a variety of formats, and this review discusses four: first, in vitro RNA and DNA monitoring; second, biosensors and biochips based on MBs; third, real-time monitoring of genes and gene expression in living systems; and finally, the next generation of molecular beacons that will be highly useful for studies with proteins, molecular beacon aptamers. These unique applications have shown that MBs holds great potential in genomics and proteomics where real-time molecular recognition with high sensitivity and excellent specificity is critical.

  11. STAT5A/B Gene Locus Undergoes Amplification during Human Prostate Cancer Progression

    PubMed Central

    Haddad, Bassem R.; Gu, Lei; Mirtti, Tuomas; Dagvadorj, Ayush; Vogiatzi, Paraskevi; Hoang, David T.; Bajaj, Renu; Leiby, Benjamin; Ellsworth, Elyse; Blackmon, Shauna; Ruiz, Christian; Curtis, Mark; Fortina, Paolo; Ertel, Adam; Liu, Chengbao; Rui, Hallgeir; Visakorpi, Tapio; Bubendorf, Lukas; Lallas, Costas D.; Trabulsi, Edouard J.; McCue, Peter; Gomella, Leonard; Nevalainen, Marja T.

    2014-01-01

    The molecular mechanisms underlying progression of prostate cancer (PCa) to castrate-resistant (CR) and metastatic disease are poorly understood. Our previous mechanistic work shows that inhibition of transcription factor Stat5 by multiple alternative methods induces extensive rapid apoptotic death of Stat5-positive PCa cells in vitro and inhibits PCa xenograft tumor growth in nude mice. Furthermore, STAT5A/B induces invasive behavior of PCa cells in vitro and in vivo, suggesting involvement of STAT5A/B in PCa progression. Nuclear STAT5A/B protein levels are increased in high-grade PCas, CR PCas, and distant metastases, and high nuclear STAT5A/B expression predicts early disease recurrence and PCa-specific death in clinical PCas. Based on these findings, STAT5A/B represents a therapeutic target protein for advanced PCa. The mechanisms underlying increased Stat5 protein levels in PCa are unclear. Herein, we demonstrate amplification at the STAT5A/B gene locus in a significant fraction of clinical PCa specimens. STAT5A/B gene amplification was more frequently found in PCas of high histologic grades and in CR distant metastases. Quantitative in situ analysis revealed that STAT5A/B gene amplification was associated with increased STAT5A/B protein expression in PCa. Functional studies showed that increased STAT5A/B copy numbers conferred growth advantage in PCa cells in vitro and as xenograft tumors in vivo. The work presented herein provides the first evidence of somatic STAT5A/B gene amplification in clinical PCas. PMID:23660011

  12. STAT5A/B gene locus undergoes amplification during human prostate cancer progression.

    PubMed

    Haddad, Bassem R; Gu, Lei; Mirtti, Tuomas; Dagvadorj, Ayush; Vogiatzi, Paraskevi; Hoang, David T; Bajaj, Renu; Leiby, Benjamin; Ellsworth, Elyse; Blackmon, Shauna; Ruiz, Christian; Curtis, Mark; Fortina, Paolo; Ertel, Adam; Liu, Chengbao; Rui, Hallgeir; Visakorpi, Tapio; Bubendorf, Lukas; Lallas, Costas D; Trabulsi, Edouard J; McCue, Peter; Gomella, Leonard; Nevalainen, Marja T

    2013-06-01

    The molecular mechanisms underlying progression of prostate cancer (PCa) to castrate-resistant (CR) and metastatic disease are poorly understood. Our previous mechanistic work shows that inhibition of transcription factor Stat5 by multiple alternative methods induces extensive rapid apoptotic death of Stat5-positive PCa cells in vitro and inhibits PCa xenograft tumor growth in nude mice. Furthermore, STAT5A/B induces invasive behavior of PCa cells in vitro and in vivo, suggesting involvement of STAT5A/B in PCa progression. Nuclear STAT5A/B protein levels are increased in high-grade PCas, CR PCas, and distant metastases, and high nuclear STAT5A/B expression predicts early disease recurrence and PCa-specific death in clinical PCas. Based on these findings, STAT5A/B represents a therapeutic target protein for advanced PCa. The mechanisms underlying increased Stat5 protein levels in PCa are unclear. Herein, we demonstrate amplification at the STAT5A/B gene locus in a significant fraction of clinical PCa specimens. STAT5A/B gene amplification was more frequently found in PCas of high histologic grades and in CR distant metastases. Quantitative in situ analysis revealed that STAT5A/B gene amplification was associated with increased STAT5A/B protein expression in PCa. Functional studies showed that increased STAT5A/B copy numbers conferred growth advantage in PCa cells in vitro and as xenograft tumors in vivo. The work presented herein provides the first evidence of somatic STAT5A/B gene amplification in clinical PCas.

  13. Molecular dynamics

    SciTech Connect

    Ladd, A.J.C.

    1988-08-01

    The basic methodology of equilibrium molecular dynamics is described. Examples from the literature are used to illustrate how molecular dynamics has been used to resolve theoretical controversies, provide data to test theories, and occasionally to discover new phenomena. The emphasis is on the application of molecular dynamics to an understanding of the microscopic physics underlying the transport properties of simple fluids. 98 refs., 4 figs.

  14. The adsorption of CO(2)/H(2)O/N(2) on 5A zeolite and silica gel in a packed column in one and two-dimensional flows

    NASA Astrophysics Data System (ADS)

    Mohamadinejad, Habib

    The purpose of this work is to develop a computer model that simulates the dynamic behavior of a Four-Bed Molecular Sieves (4-BMS) system. The system will be installed on the International Space Station for removal of CO 2/H2O/N2 on four beds that consist of 5A zeolite, 13X zeolite, and Silica gel. Due to the complexity of the actual 4-BMS, separately packed columns of 5A and Silica gel were built and tested using the model results to obtain the mass and heat transfer coefficients necessary for the development of the 4-BMS. This work begins by introducing the adsorption/desorption process in a packed column. The formulation of the simplest model of adsorption in a packed bed is developed assuming that Darcy's law. In this model, the mass and heat transport gradients are assumed to vary only in the axial direction, i.e., one-dimensional flow. The results of temperature and mass transfer breakthrough of one-dimensional flow are compared with the test results for adsorption of CO2/N2 and CO2/H2O/N2 on 5A zeolite. In the packed column near the wall boundary, the velocity decreases due to the viscous forces and the porosity increases exponentially. This near-wall region of higher porosity results in the channeling of fluid close to the wall surface. This channeling causes an early solute breakthrough relative to the center of the column. In order to accommodate the effect of porosity variation on the breakthrough, a two-dimensional model of the packed column is developed. The results of two-dimensional flow are compared with the test results for adsorption of CO2/N2 and CO2/H 2O/N2 on 5A zeolite. This work also investigates the dynamics of H2O adsorption on Silica gel material. A one-dimensional flow of a packed column bed is developed with the assumption that Darcy's law governs the momentum transport. The results of both models are compared with the test results for adsorption of H 2O/N2 on Silica gel. Finally, a computer model based on the obtained parameters of

  15. Accumulation, selection and covariation of amino acids in sieve tube sap of tansy (Tanacetum vulgare) and castor bean (Ricinus communis): evidence for the function of a basic amino acid transporter and the absence of a γ-amino butyric acid transporter.

    PubMed

    Bauer, Susanne N; Nowak, Heike; Keller, Frank; Kallarackal, Jose; Hajirezaei, Mohamad-Reza; Komor, Ewald

    2014-09-01

    Sieve tube sap was obtained from Tanacetum by aphid stylectomy and from Ricinus after apical bud decapitation. The amino acids in sieve tube sap were analyzed and compared with those from leaves. Arginine and lysine accumulated in the sieve tube sap of Tanacetum more than 10-fold compared to the leaf extracts and they were, together with asparagine and serine, preferably selected into the sieve tube sap, whereas glycine, methionine/tryptophan and γ-amino butyric acid were partially or completely excluded. The two basic amino acids also showed a close covariation in sieve tube sap. The acidic amino acids also grouped together, but antagonistic to the other amino acids. The accumulation ratios between sieve tube sap and leaf extracts were smaller in Ricinus than in Tanacetum. Arginine, histidine, lysine and glutamine were enriched and preferentially loaded into the phloem, together with isoleucine and valine. In contrast, glycine and methionine/tryptophan were partially and γ-amino butyric acid almost completely excluded from sieve tube sap. The covariation analysis grouped arginine together with several neutral amino acids. The acidic amino acids were loaded under competition with neutral amino acids. It is concluded from comparison with the substrate specificities of already characterized plant amino acid transporters, that an AtCAT1-like transporter functions in phloem loading of basic amino acids, whereas a transporter like AtGAT1 is absent in phloem. Although Tanacetum and Ricinus have different minor vein architecture, their phloem loading specificities for amino acids are relatively similar.

  16. Molecular motors

    NASA Astrophysics Data System (ADS)

    Allemand, Jean François Desbiolles, Pierre

    2015-10-01

    How do we move? More precisely, what are the molecular mechanisms that can explain that our muscles, made of very small components can move at a osopic scale? To answer these questions we must introduce molecular motors. Those motors are proteins, or small protein assemblies that, in our cells, transform chemical energy into mechanical work. Then, like we could do for a oscopic motor, used in a car or in a fan, we are going to study the basic behavior of these molecular machines, present what are their energy sources, calculate their power, their yield. If molecular motors are crucial for our oscopic movements, we are going to see that they are also essential to cellular transport and that considering the activity of some enzymes as molecular motors bring some interesting new insights on their activity.

  17. Mars Molecular and Isotopic Analysis Research Study

    NASA Technical Reports Server (NTRS)

    Manning, Heidi L. K.

    1998-01-01

    Recently, the Martian atmosphere and surface constituents have become of great interest. The Viking in situ gas chromatograph mass spectrometer experiment contributed greatly to our knowledge of the composition of the Martian atmosphere. However, important questions remain such as the abundance of water on Mars. The Viking experiment employed solid reagents to enhance their carbon measurements. Techniques of chemical conversion using simple solid reagents have advanced considerably in the past 20 years. In this investigation we researched the advancements in techniques to reversibly adsorb and desorb water and focused on the techniques potentially useful for the temperatures and pressures on the Martian surface. During the granting period from June 15, 1998 to August 14, 1998, a literature study of the material appropriate for use in a chemical conversion device and the availability of these materials were undertaken. The focus of this investigation was searching for methods and materials potentially useful in enhancing the measurements of water. Three different methods were considered for the means to extract water from a given gas sample. These methods included adsorption in a desiccant, adsorption on a clean metal surface, and adsorption in a carbon molecular sieve or zeolite. Each method was evaluated with feasibility and reversibility in mind. By far the simplest and perhaps cheapest way to remove water from a gaseous sample is by means of a bulk desiccant. Desiccants are commercially available from many companies including those that supply chemicals. The main feature of a desiccant is its ability to rapidly bind or absorb water from the atmosphere. Calcium chloride, for example, is frequently incorporated into drying tubes by organic chemists when reactions require the absence of water. Other desiccants include sodium hydroxide, calcium hydride, and commercial products such as Drierite, available from Aldrich Chemical. The disadvantage to most desiccants is

  18. Preparation of Robust, Thin Zeolite Membrane Sheet for Molecular Separation

    SciTech Connect

    Liu, Wei; Zhang, Jian; Canfield, Nathan L.; Saraf, Laxmikant V.

    2011-10-19

    This paper reports a feasibility study on the preparation of zeolite membrane films on a thin, porous metal support sheet (50-{micro}m thick). Zeolite sodium A (NaA) and silicalite zeolite frameworks are chosen to represent synthesis of respective hydrophilic-type and hydrophobic-type zeolite membranes on this new support. It is found that a dense, continuous inter-grown zeolite crystal layer at a thickness less than 2 {micro}m can be directly deposited on such a support by using direct and secondary growth techniques. The resulting membrane shows excellent adhesion on the metal sheet. Molecular-sieving functions of the prepared membranes are characterized with ethanol/water separation, CO2 separation, and air dehumidification. The results show great potential to make flexible metal-foil-like zeolite membranes for a range of energy conversion and environmental applications.

  19. Molecular engineering of porous silica using aryl templates

    DOEpatents

    Loy, D.A.; Shea, K.J.

    1994-06-14

    A process is described for manipulating the porosity of silica using a series of organic template groups covalently incorporated into the silicate matrix. The templates in the bridged polysilsesquioxanes are selectively removed from the material by oxidation with oxygen plasma or other means, leaving engineered voids or pores. The size of these pores is dependent upon the length or size of the template or spacer. The size of the templates is measured in terms of Si-Si distances which range from about 0.67 nm to 1.08 nm. Changes introduced by the loss of the templates result in a narrow range of micropores (i.e. <2 nm). Both aryl and alkyl template groups are used as spacers. Novel microporous silica materials useful as molecular sieves, desiccants, and catalyst supports are produced. 3 figs.

  20. Molecular Descriptors

    NASA Astrophysics Data System (ADS)

    Consonni, Viviana; Todeschini, Roberto

    In the last decades, several scientific researches have been focused on studying how to encompass and convert - by a theoretical pathway - the information encoded in the molecular structure into one or more numbers used to establish quantitative relationships between structures and properties, biological activities, or other experimental properties. Molecular descriptors are formally mathematical representations of a molecule obtained by a well-specified algorithm applied to a defined molecular representation or a well-specified experimental procedure. They play a fundamental role in chemistry, pharmaceutical sciences, environmental protection policy, toxicology, ecotoxicology, health research, and quality control. Evidence of the interest of the scientific community in the molecular descriptors is provided by the huge number of descriptors proposed up today: more than 5000 descriptors derived from different theories and approaches are defined in the literature and most of them can be calculated by means of dedicated software applications. Molecular descriptors are of outstanding importance in the research fields of quantitative structure-activity relationships (QSARs) and quantitative structure-property relationships (QSPRs), where they are the independent chemical information used to predict the properties of interest. Along with the definition of appropriate molecular descriptors, the molecular structure representation and the mathematical tools for deriving and assessing models are other fundamental components of the QSAR/QSPR approach. The remarkable progress during the last few years in chemometrics and chemoinformatics has led to new strategies for finding mathematical meaningful relationships between the molecular structure and biological activities, physico-chemical, toxicological, and environmental properties of chemicals. Different approaches for deriving molecular descriptors here reviewed and some of the most relevant descriptors are presented in

  1. Molecular Haeckel.

    PubMed

    Elinson, Richard P; Kezmoh, Lorren

    2010-07-01

    More than a century ago, Ernst Haeckel created embryo drawings to illustrate the morphological similarity of vertebrate early embryos. These drawings have been both widely presented and frequently criticized. At the same time that the idea of morphological similarity was recently attacked, there has been a growing realization of molecular similarities in the development of tissues and organs. We have surveyed genes expressed in vertebrate embryos, and we have used them to construct drawings that we call Molecular Haeckels. The Molecular Haeckels emphasize that, based on gene expression, there is a greater similarity among vertebrate embryos than even Haeckel might have imagined. PMID:20549737

  2. Structural complexes of the agonist, inverse agonist and antagonist bound C5a receptor: insights into pharmacology and signaling.

    PubMed

    Rana, Soumendra; Sahoo, Amita Rani; Majhi, Bharat Kumar

    2016-04-26

    The C5a receptor (C5aR) is a pharmacologically important G-protein coupled receptor (GPCR) that interacts with (h)C5a, by recruiting both the "orthosteric" sites (site1 at the N-terminus and site2 at the ECS, extra cellular surface) on C5aR in a two site-binding model. However, the complex pharmacological landscape and the distinguishing chemistry operating either at the "orthosteric" site1 or at the functionally important "orthosteric" site2 of C5aR are still not clear, which greatly limits the understanding of C5aR pharmacology. One of the major bottlenecks is the lack of an experimental structure or a refined model structure of C5aR with appropriately defined active sites. The study attempts to understand the pharmacology at the "orthosteric" site2 of C5aR rationally by generating a highly refined full-blown model structure of C5aR through advanced molecular modeling techniques, and further subjecting it to automated docking and molecular dynamics (MD) studies in the POPC bilayer. The first series of structural complexes of C5aR respectively bound to a linear native peptide agonist ((h)C5a-CT), a small molecule inverse agonist (NDT) and a cyclic peptide antagonist (PMX53) are reported, apparently establishing the unique pharmacological landscape of the "orthosteric" site2, which also illustrates an energetically distinct but coherent competitive chemistry ("cation-π" vs. "π-π" interactions) involved in distinguishing the established ligands known for targeting the "orthosteric" site2 of C5aR. Over a total of 1 μs molecular dynamics (MD) simulation in the POPC bilayer, it is evidenced that while the agonist prefers a "cation-π" interaction, the inverse agonist prefers a "cogwheel/L-shaped" interaction in contrast to the "edge-to-face/T-shaped" type π-π interactions demonstrated by the antagonist by engaging the F275(7.28) of the C5aR. In the absence of a NMR or crystallographically guided model structure of C5aR, the computational model complexes not only

  3. Sieving di-branched from mono-branched and linear alkanes using ZIF-8: experimental proof and theoretical explanation.

    PubMed

    Ferreira, Alexandre F P; Mittelmeijer-Hazeleger, Marjo C; Granato, Miguel Angelo; Martins, Vanessa F Duarte; Rodrigues, Alírio E; Rothenberg, Gadi

    2013-06-14

    We study the adsorption equilibrium isotherms and differential heats of adsorption of hexane isomers on the zeolitic imidazolate framework ZIF-8. The studies are carried out at 373 K using a manometric set-up combined with a micro-calorimeter. We see that the Langmuir model describes well the isotherms for all four isomers (n-hexane, 2-methylpentane, 2,2-dimethylbutane and 2,3-dimethylbutane). The linear and mono-branched isomers adsorb well, but 2,2-dimethylbutane is totally excluded. Plotting the differential heat of adsorption against the loading shows an initial plateau for n-hexane and 2-methylpentane. This is followed by a slow rise, indicating adsorbate-adsorbate interactions. For the di-branched isomers the differential heat of adsorption decreases with loading. To gain further insight, we ran molecular simulations using the grand-canonical Monte Carlo approach. Comparing the simulation and the experimental results shows that the ZIF framework model requires blocking of the cages, since 2,2-dimethylbutane cannot fit through the sodalite-type windows. Practically speaking, this means that ZIF-8 is a highly promising candidate for enhancing gasoline octane numbers at 373 K, as it can separate 2,2-dimethylbutane and 2,3-dimethylbutane from 2-methylpentane. Our results prove the potential of ZIF-8 as a new adsorbent that can be employed in the upgrade of the Total Isomerization Process for the production of high octane number gasoline, by blending di-branched alkanes in the gasoline.

  4. Molecular Diagnostics

    PubMed Central

    Choe, Hyonmin; Deirmengian, Carl A.; Hickok, Noreen J.; Morrison, Tiffany N.; Tuan, Rocky S.

    2015-01-01

    Orthopaedic infections are complex conditions that require immediate diagnosis and accurate identification of the causative organisms to facilitate appropriate management. Conventional methodologies for diagnosis of these infections sometimes lack accuracy or sufficient rapidity. Current molecular diagnostics are an emerging area of bench-to-bedside research in orthopaedic infections. Examples of promising molecular diagnostics include measurement of a specific biomarker in the synovial fluid, polymerase chain reaction–based detection of bacterial genes, and metabolomic determination of responses to orthopaedic infection. PMID:25808967

  5. CO2 splitting by H2O to CO and O2 under UV light in TiMCM-41silicate sieve

    SciTech Connect

    Lin, Wenyong; Han, Hongxian; Frei, Heinz

    2004-04-06

    The 266 nm light-induced reaction of CO{sub 2} and H{sub 2}O gas mixtures (including isotopic modifications {sup 13}CO{sub 2}, C{sup 18}O{sub 2}, and D{sub 2}O) in framework TiMCM-41 silicate sieve was monitored by in-situ FT-IR spectroscopy at room temperature. Carbon monoxide gas was observed as the sole product by infrared, and the growth was found to depend linearly on the photolysis laser power. H{sub 2}O was confirmed as stoichiometric electron donor. The work establishes CO as the single photon, 2-electron transfer product of CO{sub 2} photoreduction by H{sub 2}O at framework Ti centers for the first time. O{sub 2} was detected as co-product by mass spectrometric analysis of the photolysis gas mixture. These results are explained by single UV photon-induced splitting of CO{sub 2} by H{sub 2}O to CO and surface OH radical.

  6. Sieving di-branched from mono-branched and linear alkanes using ZIF-8: experimental proof and theoretical explanation.

    PubMed

    Ferreira, Alexandre F P; Mittelmeijer-Hazeleger, Marjo C; Granato, Miguel Angelo; Martins, Vanessa F Duarte; Rodrigues, Alírio E; Rothenberg, Gadi

    2013-06-14

    We study the adsorption equilibrium isotherms and differential heats of adsorption of hexane isomers on the zeolitic imidazolate framework ZIF-8. The studies are carried out at 373 K using a manometric set-up combined with a micro-calorimeter. We see that the Langmuir model describes well the isotherms for all four isomers (n-hexane, 2-methylpentane, 2,2-dimethylbutane and 2,3-dimethylbutane). The linear and mono-branched isomers adsorb well, but 2,2-dimethylbutane is totally excluded. Plotting the differential heat of adsorption against the loading shows an initial plateau for n-hexane and 2-methylpentane. This is followed by a slow rise, indicating adsorbate-adsorbate interactions. For the di-branched isomers the differential heat of adsorption decreases with loading. To gain further insight, we ran molecular simulations using the grand-canonical Monte Carlo approach. Comparing the simulation and the experimental results shows that the ZIF framework model requires blocking of the cages, since 2,2-dimethylbutane cannot fit through the sodalite-type windows. Practically speaking, this means that ZIF-8 is a highly promising candidate for enhancing gasoline octane numbers at 373 K, as it can separate 2,2-dimethylbutane and 2,3-dimethylbutane from 2-methylpentane. Our results prove the potential of ZIF-8 as a new adsorbent that can be employed in the upgrade of the Total Isomerization Process for the production of high octane number gasoline, by blending di-branched alkanes in the gasoline. PMID:23640581

  7. Recovery and characterization of Balanites aegyptiaca Del. kernel proteins. Effect of defatting, air classification, wet sieving and aqueous ethanol treatment on solubility, digestibility, amino acid composition and sapogenin content.

    PubMed

    Mohamed, A M; Wolf, W; Spiess, W E

    2000-02-01

    In order to find alternative protein sources in African regions where protein deficiency in nutrition is prevailing, solubility, in-vitro digestibility, amino acid composition and chemical score of Balanites aegyptiaca Del. kernel proteins were investigated as a function of different processing steps including defatting, air classification, wet sieving and aqueous ethanol treatment. Air classification delivered a fine fraction of 58.1% of the total protein. Applying a wet sieving process, a protein concentrate of 72.9% protein content was achieved but the recovery was very low (35.6%). However, in case of isoelectric precipitation followed by aqueous ethanol treatment both protein content (78.2%) and recovery (53.7%) were high. Data concerning the chemical score revealed, that lysine content of the defatted kernel flour amounted to 74.2% of the recommended FAO/WHO standard level. In-vitro protein digestibility was found to be higher than of legume proteins. The digestible protein of the full fat flour, defatted flour, air classified and wet sieved fine fractions and protein concentrate were 91.9, 93.7, 82.0, 86.4 and 94.2%, respectively. The sapogenin content per 100 g protein of the investigated protein preparations was significantly lower (46% to 62%) than of the initial material (oilcake).

  8. Molecular fountain.

    SciTech Connect

    Strecker, Kevin E.; Chandler, David W.

    2009-09-01

    A molecular fountain directs slowly moving molecules against gravity to further slow them to translational energies that they can be trapped and studied. If the molecules are initially slow enough they will return some time later to the position from which they were launched. Because this round trip time can be on the order of a second a single molecule can be observed for times sufficient to perform Hz level spectroscopy. The goal of this LDRD proposal was to construct a novel Molecular Fountain apparatus capable of producing dilute samples of molecules at near zero temperatures in well-defined user-selectable, quantum states. The slowly moving molecules used in this research are produced by the previously developed Kinematic Cooling technique, which uses a crossed atomic and molecular beam apparatus to generate single rotational level molecular samples moving slowly in the laboratory reference frame. The Kinematic Cooling technique produces cold molecules from a supersonic molecular beam via single collisions with a supersonic atomic beam. A single collision of an atom with a molecule occurring at the correct energy and relative velocity can cause a small fraction of the molecules to move very slowly vertically against gravity in the laboratory. These slowly moving molecules are captured by an electrostatic hexapole guiding field that both orients and focuses the molecules. The molecules are focused into the ionization region of a time-of-flight mass spectrometer and are ionized by laser radiation. The new molecular fountain apparatus was built utilizing a new design for molecular beam apparatus that has allowed us to miniaturize the apparatus. This new design minimizes the volumes and surface area of the machine allowing smaller pumps to maintain the necessary background pressures needed for these experiments.

  9. Effective suppression of C5a-induced proinflammatory response using anti-human C5a repebody.

    PubMed

    Hwang, Da-Eun; Choi, Jung-Min; Yang, Chul-Su; Lee, Joong-Jae; Heu, Woosung; Jo, Eun-Kyeong; Kim, Hak-Sung

    2016-09-01

    The strongest anaphylatoxin, C5a, plays a critical role in the proinflammatory responses, causing the pathogenesis of a number of inflammatory diseases including sepsis, asthma, and rheumatoid arthritis. Inhibitors of C5a thus have great potential as therapeutics for various inflammatory disorders. Herein, we present the development of a high-affinity repebody against human C5a (hC5a), which effectively suppresses the proinflammatory response. A repebody scaffold composed of leucine-rich repeat (LRR) modules was previously developed as an alternative protein scaffold. A repebody specifically binding to hC5a was selected through a phage display, and its affinity was increased up to 5 nM using modular engineering. The repebody was shown to effectively inhibit the production of C5a-induced proinflammatory cytokines by human monocytes. To obtain insight into a mode of action by the repebody, we determined its crystal structure in complex with hC5a. A structural analysis revealed that the repebody binds to the D1 and D3 regions of hC5a, overlapping several epitope residues with the hC5a receptor (hC5aR). It is thus likely that the repebody suppresses the hC5a-mediated immune response in monocytes by blocking the binding of hC5a to its receptor. The anti-hC5a repebody can be developed as a potential therapeutic for C5a-involved inflammatory diseases. PMID:27416759

  10. Wnt5a attenuates hypoxia-induced pulmonary arteriolar remodeling and right ventricular hypertrophy in mice

    PubMed Central

    Jin, Yuling; Wang, Wang; Chai, Sanbao; Liu, Jie

    2015-01-01

    Hypoxic pulmonary hypertension (HPH), which is characterized by pulmonary arteriolar remodeling and right ventricular hypertrophy, is still a life-threatening disease with the current treatment strategies. The underlying molecular mechanisms of HPH remain unclear. Our previously published study showed that Wnt5a, one of the ligands in the Wnt family, was critically involved in the inhibition of hypoxia-induced pulmonary arterial smooth muscle cell proliferation by downregulation of β-catenin/cyclin D1 in vitro. In this study, we investigated the possible functions and mechanisms of Wnt5a in HPH in vivo. Recombinant mouse Wnt5a (rmWnt5a) or phosphate buffered saline (PBS) was administered to male C57/BL6 mice weekly from the first day to the end of the two or four weeks after exposed to hypoxia (10% O2). Hypoxia-induced pulmonary hypertension was associated with a marked increase in β-catenin/cyclin D1 expression in lungs. Right ventricular systolic pressure and right ventricular hypertrophy index were reduced in animals treated with rmWnt5a compared with PBS. Histology showed less pulmonary vascular remodeling and right ventricular hypertrophy in the group treated with rmWnt5a than with PBS. Treatment with rmWnt5a resulted in a concomitant reduction in β-catenin/cyclin D1 levels in lungs. These data demonstrate that Wnt5a exerts its beneficial effects on HPH by regulating pulmonary vascular remodeling and right ventricular hypertrophy in a manner that is associated with reduction in β-catenin/cyclin D1 signaling. A therapy targeting the β-catenin/cyclin D1 signaling pathway might be a potential strategy for HPH treatment. PMID:25956683

  11. A Wnt5a signaling pathway in the pathogenesis of HIV-1 gp120-induced pain.

    PubMed

    Yuan, Su-Bo; Ji, Guangchen; Li, Bei; Andersson, Tommy; Neugebauer, Volker; Tang, Shao-Jun

    2015-07-01

    Pathological pain is one of the most common neurological complications in patients with HIV-1/AIDS. However, the pathogenic process is unclear. Our recent studies show that Wnt5a is upregulated in the spinal cord dorsal horn (SDH) of the patients with HIV who develop pain and that HIV-1 gp120, a potential causal factor of the HIV-associated pain, rapidly upregulates Wnt5a in the mouse SDH. Using a mouse model, we show here that a specific Wnt5a antagonist, Box-5, attenuated gp120-induced mechanical allodynia. Conversely, a Wnt5a agonist, Foxy5, facilitated the allodynia. To elucidate the molecular mechanism by which Wnt5a regulates gp120-induced allodynia, we tested the role of the JNK/TNF-α pathway. We observed that the JNK-specific inhibitor SP600125 blocked either gp120- or Foxy5-induced allodynia. Similarly, the TNF-α-specific antagonist Enbrel also reversed either gp120- or Foxy5-induced allodynia. These data suggest that JNK and TNF-α mediate the biological effects of Wnt5a in regulating gp120-induced allodynia. To investigate the cellular mechanism, we performed extracellular single-unit recording from SDH neurons in anesthetized mice. Both Box-5 and SP600125 negated gp120-induced potentiation of SDH neuron spiking evoked by mechanical stimulation of the hind paw. Furthermore, while Foxy5 potentiated spike frequency of SDH neurons, either SP600125 or Enbrel blocked the potentiation. The data indicate that Wnt5a potentiates the activity of SDH neurons through the JNK-TNF-α pathway. Collectively, our findings suggest that Wnt5a regulates the pathogenesis of gp120-induced pain, likely by sensitizing pain-processing SDH neurons through JNK/TNF-α signaling.

  12. Wnt5a attenuates hypoxia-induced pulmonary arteriolar remodeling and right ventricular hypertrophy in mice.

    PubMed

    Jin, Yuling; Wang, Wang; Chai, Sanbao; Liu, Jie; Yang, Ting; Wang, Jun

    2015-12-01

    Hypoxic pulmonary hypertension (HPH), which is characterized by pulmonary arteriolar remodeling and right ventricular hypertrophy, is still a life-threatening disease with the current treatment strategies. The underlying molecular mechanisms of HPH remain unclear. Our previously published study showed that Wnt5a, one of the ligands in the Wnt family, was critically involved in the inhibition of hypoxia-induced pulmonary arterial smooth muscle cell proliferation by downregulation of β-catenin/cyclin D1 in vitro. In this study, we investigated the possible functions and mechanisms of Wnt5a in HPH in vivo. Recombinant mouse Wnt5a (rmWnt5a) or phosphate buffered saline (PBS) was administered to male C57/BL6 mice weekly from the first day to the end of the two or four weeks after exposed to hypoxia (10% O2). Hypoxia-induced pulmonary hypertension was associated with a marked increase in β-catenin/cyclin D1 expression in lungs. Right ventricular systolic pressure and right ventricular hypertrophy index were reduced in animals treated with rmWnt5a compared with PBS. Histology showed less pulmonary vascular remodeling and right ventricular hypertrophy in the group treated with rmWnt5a than with PBS. Treatment with rmWnt5a resulted in a concomitant reduction in β-catenin/cyclin D1 levels in lungs. These data demonstrate that Wnt5a exerts its beneficial effects on HPH by regulating pulmonary vascular remodeling and right ventricular hypertrophy in a manner that is associated with reduction in β-catenin/cyclin D1 signaling. A therapy targeting the β-catenin/cyclin D1 signaling pathway might be a potential strategy for HPH treatment.

  13. Inhibition of C5a receptor alleviates experimental CNS lupus.

    PubMed

    Jacob, Alexander; Hack, Bradley; Bai, Tao; Brorson, James R; Quigg, Richard J; Alexander, Jessy J

    2010-04-15

    To investigate the role of C5a generated on complement activation in brain, the lupus model, MRL/lpr mice were treated with C5a receptor(R) antagonist (ant). Neutrophil infiltration, ICAM, TNF-alpha and iNOS mRNA expression, neuronal apoptosis and the expression of p-JNK, pSTAT1 and p-Erk were reduced and p-Akt increased on C5aR inhibition in MRL/lpr brains. MRL/lpr serum caused increased apoptosis in neurons showing that lupus had a direct effect on these cells. C5aRant pretreatment prevented the lupus serum induced loss of neuronal cells. Our findings demonstrate for the first time that C5a/C5aR signaling plays an important role in the pathogenesis of CNS lupus.

  14. Inhibition of C5a receptor alleviates experimental CNS lupus

    PubMed Central

    Jacob, Alexander; Hack, Bradley; Bai, Tao; Brorson, James R.; Quigg, Richard J.; Alexander, Jessy J.

    2010-01-01

    To investigate the role of C5a generated on complement activation in brain, the lupus model, MRL/lpr mice were treated with C5a receptor(R) antagonist (ant). Neutrophil infiltration, ICAM, TNF-α and iNOS mRNA expression, neuronal apoptosis and the expression of p-JNK, pSTAT1 and p-Erk were reduced and p-Akt increased on C5aR inhibition in MRL/lpr brains. MRL/lpr serum caused increased apoptosis in neurons showing that lupus had a direct effect on these cells. C5aRant pretreatment prevented the lupus serum induced loss of neuronal cells. Our findings demonstrate for the first time that C5a/C5aR signaling plays an important role in the pathogenesis of CNS lupus. PMID:20207017

  15. Molecular Electronics

    NASA Astrophysics Data System (ADS)

    Petty, Michael

    The prospects of using organic materials in electronics and optoelectronics applications have attracted scientists and technologists since the 1970s. This field has become known as molecular electronics. Some successes have already been achieved, for example the liquid-crystal display. Other products such as organic light-emitting displays, chemical sensors and plastic transistors are developing fast. There is also a keen interest in exploiting technologies at the molecular scale that might eventually replace silicon devices. This chapter provides some of the background physics and chemistry to the interdisciplinary subject of molecular electronics. A review of some of the possible application areas for organic materials is presented and some speculation is provided regarding future directions.

  16. Structural disorganization of pronephric glomerulus in zebrafish mpp5a/nagie oko mutant

    PubMed Central

    Ichimura, Koichiro; Fukuyo, Yayoi; Nakamura, Tomomi; Powell, Rebecca; Sakai, Tatsuo; Obara, Tomoko

    2012-01-01

    Background The podocyte slit diaphragm (SD) is an essential component of the selective filtration barrier in the glomerulus. Several structural proteins required for formation and maintenance of SD have been identified; however, molecular mechanisms regulating these proteins are still limited. Results Here, we demonstrate that MAGUK p55 subfamily member 5a (Mpp5a)/Nagie oko, a component of the Crb multi-protein complex, was colocalized with an SD-associated protein ZO-1 in the zebrafish pronephric glomerulus. To characterize the function of Mpp5a, zebrafish mpp5am520 mutant embryos, which are known to have defects in cardiac and neuronal morphogenesis, were analyzed. These mutants failed to merge the bilateral glomerular primordia and to form the glomerular capillary and mesangium, but the foot processes and SD showed normal appearance. The structural disorganization in the mpp5am520 mutant glomerulus was quite similar to that of a cardiac troponin T2a/tnnt2a/silent heart knockdown zebrafish, which exhibited circulatory failure due to lack of heart beating. Conclusions Mpp5a is not prerequisite to form podocyte slit diaphragm in the pronephric glomerular development in zebrafish. The structural disorganization of the pronephric glomerulus in the mpp5am520 mutant is likely to result from circulatory failure, rather than the anomaly of Mpp5a protein in the glomerulus. PMID:23027442

  17. Nuclear receptor NR5A2 controls neural stem cell fate decisions during development

    PubMed Central

    Stergiopoulos, Athanasios; Politis, Panagiotis K.

    2016-01-01

    The enormous complexity of mammalian central nervous system (CNS) is generated by highly synchronized actions of diverse factors and signalling molecules in neural stem/progenitor cells (NSCs). However, the molecular mechanisms that integrate extrinsic and intrinsic signals to control proliferation versus differentiation decisions of NSCs are not well-understood. Here we identify nuclear receptor NR5A2 as a central node in these regulatory networks and key player in neural development. Overexpression and loss-of-function experiments in primary NSCs and mouse embryos suggest that NR5A2 synchronizes cell-cycle exit with induction of neurogenesis and inhibition of astrogliogenesis by direct regulatory effects on Ink4/Arf locus, Prox1, a downstream target of proneural genes, as well as Notch1 and JAK/STAT signalling pathways. Upstream of NR5a2, proneural genes, as well as Notch1 and JAK/STAT pathways control NR5a2 endogenous expression. Collectively, these observations render NR5A2 a critical regulator of neural development and target gene for NSC-based treatments of CNS-related diseases. PMID:27447294

  18. Extended phenotypic spectrum of KIF5A mutations

    PubMed Central

    Liu, Yo-Tsen; Laurá, Matilde; Hersheson, Joshua; Horga, Alejandro; Jaunmuktane, Zane; Brandner, Sebastian; Pittman, Alan; Hughes, Deborah; Polke, James M.; Sweeney, Mary G.; Proukakis, Christos; Janssen, John C.; Auer-Grumbach, Michaela; Zuchner, Stephan; Shields, Kevin G.; Reilly, Mary M.

    2014-01-01

    Objective: To establish the phenotypic spectrum of KIF5A mutations and to investigate whether KIF5A mutations cause axonal neuropathy associated with hereditary spastic paraplegia (HSP) or typical Charcot-Marie-Tooth disease type 2 (CMT2). Methods: KIF5A sequencing of the motor-domain coding exons was performed in 186 patients with the clinical diagnosis of HSP and in 215 patients with typical CMT2. Another 66 patients with HSP or CMT2 with pyramidal signs were sequenced for all exons of KIF5A by targeted resequencing. One additional patient was genetically diagnosed by whole-exome sequencing. Results: Five KIF5A mutations were identified in 6 unrelated patients: R204W and D232N were novel mutations; R204Q, R280C, and R280H have been previously reported. Three patients had CMT2 as the predominant and presenting phenotype; 2 of them also had pyramidal signs. The other 3 patients presented with HSP but also had significant axonal neuropathy or other additional features. Conclusion: This is currently the largest study investigating KIF5A mutations. By combining next-generation sequencing and conventional sequencing, we confirm that KIF5A mutations can cause variable phenotypes ranging from HSP to CMT2. The identification of mutations in CMT2 broadens the phenotypic spectrum and underlines the importance of KIF5A mutations, which involve degeneration of both the central and peripheral nervous systems and should be tested in HSP and CMT2. PMID:25008398

  19. 42 CFR 5a.3 - Definition of Underserved Rural Community.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 42 Public Health 1 2010-10-01 2010-10-01 false Definition of Underserved Rural Community. 5a.3... PROVISIONS RURAL PHYSICIAN TRAINING GRANT PROGRAM § 5a.3 Definition of Underserved Rural Community. Underserved Rural Community means a community: (a) Located in: (1) A non-Metropolitan County or...

  20. 42 CFR 5a.3 - Definition of Underserved Rural Community.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 42 Public Health 1 2011-10-01 2011-10-01 false Definition of Underserved Rural Community. 5a.3 Section 5a.3 Public Health PUBLIC HEALTH SERVICE, DEPARTMENT OF HEALTH AND HUMAN SERVICES GENERAL... Professions Shortage Area, (under section 332(a)(1)(A) of the Public Health Service Act) or (2)...

  1. 42 CFR 5a.1 - Statutory basis and purpose.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 42 Public Health 1 2010-10-01 2010-10-01 false Statutory basis and purpose. 5a.1 Section 5a.1 Public Health PUBLIC HEALTH SERVICE, DEPARTMENT OF HEALTH AND HUMAN SERVICES GENERAL PROVISIONS RURAL... the Public Health Service Act. These provisions define “underserved rural community” for purposes...

  2. 42 CFR 5a.1 - Statutory basis and purpose.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 42 Public Health 1 2011-10-01 2011-10-01 false Statutory basis and purpose. 5a.1 Section 5a.1 Public Health PUBLIC HEALTH SERVICE, DEPARTMENT OF HEALTH AND HUMAN SERVICES GENERAL PROVISIONS RURAL... the Public Health Service Act. These provisions define “underserved rural community” for purposes...

  3. Molecular simulations and experimental studies of zeolites

    NASA Astrophysics Data System (ADS)

    Moloy, Eric C.

    Zeolites are microporous aluminosilicate tetrahedral framework materials that have symmetric cages and channels with open-diameters between 0.2 and 2.0 nm. Zeolites are used extensively in the petrochemical industries for both their microporosity and their catalytic properties. The role of water is paramount to the formation, structure, and stability of these materials. Zeolites frequently have extra-framework cations, and as a result, are important ion-exchange materials. Zeolites also play important roles as molecular sieves and catalysts. For all that is known about zeolites, much remains a mystery. How, for example, can the well established metastability of these structures be explained? What is the role of water with respect to the formation, stabilization, and dynamical properties? This dissertation addresses these questions mainly from a modeling perspective, but also with some experimental work as well. The first discussion addresses a special class of zeolites: pure-silica zeolites. Experimental enthalpy of formation data are combined with molecular modeling to address zeolitic metastability. Molecular modeling is used to calculate internal surface areas, and a linear relationship between formation enthalpy and internal surface areas is clearly established, producing an internal surface energy of approximately 93 mJ/m2. Nitrate bearing sodalite and cancrinite have formed under the caustic chemical conditions of some nuclear waste processing centers in the United States. These phases have fouled expensive process equipment, and are the primary constituents of the resilient heels in the bottom of storage tanks. Molecular modeling, including molecular mechanics, molecular dynamics, and density functional theory, is used to simulate these materials with respect to structure and dynamical properties. Some new, very interesting results are extracted from the simulation of anhydrous Na6[Si6Al 6O24] sodalite---most importantly, the identification of two distinct

  4. In planta differential targeting analysis of Thermotoga maritima Cel5A and CBM6-engineered Cel5A for autohydrolysis.

    PubMed

    Mahadevan, Shobana Arumugam; Wi, Seung Gon; Kim, Yeon Ok; Lee, Kwang Ho; Bae, Hyeun-Jong

    2011-08-01

    The heterologous expression of glycosyl hydrolases in bioenergy crops can improve the lignocellulosic conversion process for ethanol production. We attempted to obtain high-level expression of an intact Thermotoga maritima endoglucanase, Cel5A, and CBM6-engineered Cel5A in transgenic tobacco plants for the mass production and autohydrolysis of endoglucanase. Cel5A expression was targeted to different subcellular compartments, namely, the cytosol, apoplast, and chloroplast, using the native form of the pathogenesis-related protein 1a (PR1a) and Rubisco activase (RA) transit peptides. Cel5A transgenic tobacco plants with the chloroplast transit peptide showed the highest average endoglucanase activity and protein accumulation up to 4.5% total soluble protein. Cel5A-CBM6 was targeted to the chloroplast and accumulated up to 5.2% total soluble protein. In terms of the direct conversion of plant tissue into free sugar, the Cel5A-CBM6 transgenic plant was 33% more efficient than the Cel5A transgenic plant. The protein stability of Cel5A and Cel5A-CBM6 in lyophilized leaf material is an additional advantage in the bioconversion process.

  5. Synergistic Activity of Combined NS5A Inhibitors

    PubMed Central

    Nower, Peter T.; Gao, Min; Fridell, Robert; Wang, Chunfu; Hewawasam, Piyasena; Lopez, Omar; Tu, Yong; Meanwell, Nicholas A.; Belema, Makonen; Roberts, Susan B.; Cockett, Mark; Sun, Jin-Hua

    2015-01-01

    Daclatasvir (DCV) is a first-in-class hepatitis C virus (HCV) nonstructural 5A replication complex inhibitor (NS5A RCI) that is clinically effective in interferon-free combinations with direct-acting antivirals (DAAs) targeting alternate HCV proteins. Recently, we reported NS5A RCI combinations that enhance HCV inhibitory potential in vitro, defining a new class of HCV inhibitors termed NS5A synergists (J. Sun, D. R. O’Boyle II, R. A. Fridell, D. R. Langley, C. Wang, S. Roberts, P. Nower, B. M. Johnson F. Moulin, M. J. Nophsker, Y. Wang, M. Liu, K. Rigat, Y. Tu, P. Hewawasam, J. Kadow, N. A. Meanwell, M. Cockett, J. A. Lemm, M. Kramer, M. Belema, and M. Gao, Nature 527:245–248, 2015, doi:10.1038/nature15711). To extend the characterization of NS5A synergists, we tested new combinations of DCV and NS5A synergists against genotype (gt) 1 to 6 replicons and gt 1a, 2a, and 3a viruses. The kinetics of inhibition in HCV-infected cells treated with DCV, an NS5A synergist (NS5A-Syn), or a combination of DCV and NS5A-Syn were distinctive. Similar to activity observed clinically, DCV caused a multilog drop in HCV, followed by rebound due to the emergence of resistance. DCV–NS5A-Syn combinations were highly efficient at clearing cells of viruses, in line with the trend seen in replicon studies. The retreatment of resistant viruses that emerged using DCV monotherapy with DCV–NS5A-Syn resulted in a multilog drop and rebound in HCV similar to the initial decline and rebound observed with DCV alone on wild-type (WT) virus. A triple combination of DCV, NS5A-Syn, and a DAA targeting the NS3 or NS5B protein cleared the cells of viruses that are highly resistant to DCV. Our data support the observation that the cooperative interaction of DCV and NS5A-Syn potentiates both the genotype coverage and resistance barrier of DCV, offering an additional DAA option for combination therapy and tools for explorations of NS5A function. PMID:26711745

  6. Affinity labeling of (2'-5')-oligoadenylate-activated endonuclease with (/sup 32/P)-2', 5'A and its analogs

    SciTech Connect

    Saarma, M.Y.; Gordon, J.; Minks, M.A.

    1985-09-01

    This paper examines the role interferons play in the origin of the antiviral state of cells and in the inhibition of virus reproduction. Treatment of cells with interferon induces the synthesis of a whole series of proteins. For affinity labeling of 2', 5'A-dependent endoribonuclease, the authors synthesized P-32 labeled 2; 5'A by two methods. Results of the investigation show that the most probable candidate for 2', 5'A-dependent endoribonuclease is the protein with molecular weight 80,000. The role of the other two proteins is still unknown.

  7. Molecular gastronomy

    NASA Astrophysics Data System (ADS)

    This, Hervé

    2005-01-01

    For centuries, cooks have been applying recipes without looking for the mechanisms of the culinary transformations. A scientific discipline that explores these changes from raw ingredients to eating the final dish, is developing into its own field, termed molecular gastronomy. Here, one of the founders of the discipline discusses its aims and importance.

  8. Thermal and hydraulic performance tests of a sieve-tray direct-contact heat exchanger vaporizing pure and mixed-hydrocarbon Rankine-cycle working fluids

    SciTech Connect

    Mines, G.L.; Demuth, O.J.; Wiggins, D.J.

    1983-08-01

    Experiments investigating a sieve-tray direct-contact heat exchanger were conducted at the Raft River Geothermal Test Site in southeastern Idaho using the 60-kW Mobile Heat Cycle Research Facility operating in the thermal loop mode (without a turbine). Isobutane, propane, and several hydrocarbon mixtures were heated and boiled in the direct-contact column, which is approx. 12 in. in diameter and 19-1/2 ft. high, using the energy from a 280/sup 0/F geothermal resource. Using pure fluids, isobutane or propane, the column operated much as intended, with 17 trays used for preheating and one or two accomplishing the boiling. For the pure fluids, individual tray efficiencies were found to be 70% or higher for preheating, and close to 100% for boiling; column pinch points were projected to be well under 1/sup 0/F with some runs reaching values as low as approx. 0.02/sup 0/F. Maximum geofluid throughputs for the isobutane tests corresponded roughly to the terminal rise velocity of a 1/32 in. working fluid droplet in geofluid. Boiling was found to occur in as many as 12 trays for the mixtures having the highest concentrations of the minor component, with overall efficiencies in the boiling section estimated on the order of 25 or 30%. Preheating tray efficiencies appeared to be fairly independent of working fluid, with pinch points ranging from as low as approx. 0.03/sup 0/F for a 0.95 isobutane/0.05 hexane mixture to approx. 2.3/sup 0/F for a 0.85 isobutane/0.05 hexane mixture. Column operation was noticeably less stable for the mixtures than for the pure fluids, with maximum throughputs dropping to as low as 40 to 50% of those for the pure fluids.

  9. Digester performance and microbial community changes in thermophilic and mesophilic sequencing batch reactors fed with the fine sieved fraction of municipal sewage.

    PubMed

    Ghasimi, Dara S M; Tao, Yu; de Kreuk, Merle; Abbas, Ben; Zandvoort, Marcel H; van Lier, Jules B

    2015-12-15

    This study investigates the start-up and operation of bench-scale mesophilic (35 °C) and thermophilic (55 °C) anaerobic sequencing batch reactor (SBR) digesters treating the fine sieved fraction (FSF) from raw municipal sewage. FSF was sequestered from raw municipal wastewater, in the Netherlands, using a rotating belt filter equipped with a 350 micron mesh. For the given wastewater, the major component of FSF was toilet paper, which is estimated to be 10-14 kg per year per average person in the western European countries. A seven months adaptation time was allowed for the thermophilic and mesophilic digesters in order to adapt to FSF as the sole substrate with varying dry solids content of 10-25%. Different SBR cycle durations (14, 9 and 2 days) were applied for both temperature conditions to study methane production rates, volatile fatty acids (VFAs) dynamics, lag phases, as well as changes in microbial communities. The prevailing sludge in the two digesters consisted of very different bacterial and archaeal communities, with OP9 lineage and Methanothermobacter being pre-dominant in the thermophilic digester and Bacteroides and Methanosaeta dominating the mesophilic one. Eventually, decreasing the SBR cycle period, thus increasing the FSF load, resulted in improved digester performances, particularly with regard to the thermophilic digester, i.e. shortened lag phases following the batch feedings, and reduced VFA peaks. Over time, the thermophilic digester outperformed the mesophilic one with 15% increased volatile solids (VS) destruction, irrespective to lower species diversity found at high temperature.

  10. Digester performance and microbial community changes in thermophilic and mesophilic sequencing batch reactors fed with the fine sieved fraction of municipal sewage.

    PubMed

    Ghasimi, Dara S M; Tao, Yu; de Kreuk, Merle; Abbas, Ben; Zandvoort, Marcel H; van Lier, Jules B

    2015-12-15

    This study investigates the start-up and operation of bench-scale mesophilic (35 °C) and thermophilic (55 °C) anaerobic sequencing batch reactor (SBR) digesters treating the fine sieved fraction (FSF) from raw municipal sewage. FSF was sequestered from raw municipal wastewater, in the Netherlands, using a rotating belt filter equipped with a 350 micron mesh. For the given wastewater, the major component of FSF was toilet paper, which is estimated to be 10-14 kg per year per average person in the western European countries. A seven months adaptation time was allowed for the thermophilic and mesophilic digesters in order to adapt to FSF as the sole substrate with varying dry solids content of 10-25%. Different SBR cycle durations (14, 9 and 2 days) were applied for both temperature conditions to study methane production rates, volatile fatty acids (VFAs) dynamics, lag phases, as well as changes in microbial communities. The prevailing sludge in the two digesters consisted of very different bacterial and archaeal communities, with OP9 lineage and Methanothermobacter being pre-dominant in the thermophilic digester and Bacteroides and Methanosaeta dominating the mesophilic one. Eventually, decreasing the SBR cycle period, thus increasing the FSF load, resulted in improved digester performances, particularly with regard to the thermophilic digester, i.e. shortened lag phases following the batch feedings, and reduced VFA peaks. Over time, the thermophilic digester outperformed the mesophilic one with 15% increased volatile solids (VS) destruction, irrespective to lower species diversity found at high temperature. PMID:25976021

  11. Structural basis for the targeting of complement anaphylatoxin C5a using a mixed L-RNA/L-DNA aptamer

    NASA Astrophysics Data System (ADS)

    Yatime, Laure; Maasch, Christian; Hoehlig, Kai; Klussmann, Sven; Andersen, Gregers R.; Vater, Axel

    2015-04-01

    L-Oligonucleotide aptamers (Spiegelmers) consist of non-natural L-configured nucleotides and are of particular therapeutic interest due to their high resistance to plasma nucleases. The anaphylatoxin C5a, a potent inflammatory mediator generated during complement activation that has been implicated with organ damage, can be efficiently targeted by Spiegelmers. Here, we present the first crystallographic structures of an active Spiegelmer, NOX-D20, bound to its physiological targets, mouse C5a and C5a-desArg. The structures reveal a complex 3D architecture for the L-aptamer that wraps around C5a, including an intramolecular G-quadruplex stabilized by a central Ca2+ ion. Functional validation of the observed L-aptamer:C5a binding mode through mutational studies also rationalizes the specificity of NOX-D20 for mouse and human C5a against macaque and rat C5a. Finally, our structural model provides the molecular basis for the Spiegelmer affinity improvement through positional L-ribonucleotide to L-deoxyribonucleotide exchanges and for its inhibition of the C5a:C5aR interaction.

  12. Structural basis for the targeting of complement anaphylatoxin C5a using a mixed L-RNA/L-DNA aptamer

    PubMed Central

    Yatime, Laure; Maasch, Christian; Hoehlig, Kai; Klussmann, Sven; Andersen, Gregers R.; Vater, Axel

    2015-01-01

    L-Oligonucleotide aptamers (Spiegelmers) consist of non-natural L-configured nucleotides and are of particular therapeutic interest due to their high resistance to plasma nucleases. The anaphylatoxin C5a, a potent inflammatory mediator generated during complement activation that has been implicated with organ damage, can be efficiently targeted by Spiegelmers. Here, we present the first crystallographic structures of an active Spiegelmer, NOX-D20, bound to its physiological targets, mouse C5a and C5a-desArg. The structures reveal a complex 3D architecture for the L-aptamer that wraps around C5a, including an intramolecular G-quadruplex stabilized by a central Ca2+ ion. Functional validation of the observed L-aptamer:C5a binding mode through mutational studies also rationalizes the specificity of NOX-D20 for mouse and human C5a against macaque and rat C5a. Finally, our structural model provides the molecular basis for the Spiegelmer affinity improvement through positional L-ribonucleotide to L-deoxyribonucleotide exchanges and for its inhibition of the C5a:C5aR interaction. PMID:25901944

  13. Molecular thermometry.

    PubMed

    McCabe, Kevin M; Hernandez, Mark

    2010-05-01

    Conventional temperature measurements rely on material responses to heat, which can be detected visually. When Galileo developed an air expansion based device to detect temperature changes, Santorio, a contemporary physician, added a scale to create the first thermometer. With this instrument, patients' temperatures could be measured, recorded, and related to changing health conditions. Today, advances in materials science and bioengineering provide new ways to report temperature at the molecular level in real time. In this review, the scientific foundations and history of thermometry underpin a discussion of the discoveries emerging from the field of molecular thermometry. Intracellular nanogels and heat sensing biomolecules have been shown to accurately report temperature changes at the nanoscale. Various systems will soon provide the ability to accurately measure temperature changes at the tissue, cellular, and even subcellular level, allowing for detection and monitoring of very small changes in local temperature. In the clinic, this will lead to enhanced detection of tumors and localized infection, and accurate and precise monitoring of hyperthermia-based therapies. Some nanomaterial systems have even demonstrated a theranostic capacity for heat-sensitive, local delivery of chemotherapeutics. Just as early thermometry rapidly moved into the clinic, so too will these molecular thermometers.

  14. Molecular Imprinting

    NASA Astrophysics Data System (ADS)

    Dufaud, V.; Bonneviot, L.

    Our senses of smell and taste are able to recognise molecules selectively, to the point where they can even discriminate between different chiral states. This property, called molecular recognition, is essential to all forms of life [1]. It is based on the principle of a specific interaction between a receptor or host and a target molecule, which will be identified among a multitude of others, then selectively adsorbed. If the host is endowed with reactive functions, the attached molecule may be transported or transformed. Enzymes are the archetypal host molecules exploiting the idea of molecular recognition. Their complexation sites comprise a hydrophobic pocket with definite shape within which amino acid residues are located in a precisely defined way. The combined effect of these different characteristics underlies not only the affinity for some specific substrate, but also the transformation of this substrate into the desired product [2]. In fact, the phenomena actually brought into play are much more involved, being made up of an ensemble of physicochemical events that act together in a cooperative way, either simultaneously or sequentially, and in which the molecular processes are difficult to follow in detail.

  15. Molecular Thermometry

    PubMed Central

    McCabe, Kevin M.; Hernandez, Mark

    2010-01-01

    Conventional temperature measurements rely on material responses to heat, which can be detected visually. When Galileo developed an air expansion based device to detect temperature changes, Santorio, a contemporary physician, added a scale to create the first thermometer. With this instrument, patients’ temperatures could be measured, recorded and related to changing health conditions. Today, advances in materials science and bioengineering provide new ways to report temperature at the molecular level in real time. In this review the scientific foundations and history of thermometry underpin a discussion of the discoveries emerging from the field of molecular thermometry. Intracellular nanogels and heat sensing biomolecules have been shown to accurately report temperature changes at the nano-scale. Various systems will soon provide the ability to accurately measure temperature changes at the tissue, cellular, and even sub-cellular level, allowing for detection and monitoring of very small changes in local temperature. In the clinic this will lead to enhanced detection of tumors and localized infection, and accurate and precise monitoring of hyperthermia based therapies. Some nanomaterial systems have even demonstrated a theranostic capacity for heat-sensitive, local delivery of chemotherapeutics. Just as early thermometry moved into the clinic, so too will these molecular thermometers. PMID:20139796

  16. [Involvement of nonstructural protein 5A and lipids on production of hepatitis C virus particles].

    PubMed

    Suzuki, Tetsuro; Masaki, Takahiro; Aizaki, Hideki

    2008-12-01

    A robust system for production of recombinant infectious hepatitis C virus (HCV) has been established in 2005 and classical virological techniques are now able to be applied to the HCV research, especially regarding molecular mechanisms on virion assembly and maturation. We recently demonstrated that the C-terminal serine cluster of NS5A is a determinant of NS5A interaction with Core and the subcellular localization of NSSA. Mutation of this cluster blocks the NS5A-Core interaction, resulting in perturbation of association between Core and HCV RNA. It is thus tempting to consider that NS5A plays a key role in transporting the viral genome RNA synthesized by the replication complex to the surface of lipid droplets (LDs) or LD-associated membranes, where Core localizes, leading to facilitation of nucleocapsid formation. We also demonstrated an important role of cholesterol and sphingolipid in HCV infection and virion maturation. Specifically, mature HCV particles are rich in cholesterol. Depletion of cholesterol from HCV or hydrolysis of virion-associated sphingomyelin results in a loss of infectivity, and the addition of exogenous cholesterol restores infectivity. In addition, cholesterol and sphingolipid on the HCV membrane play a key role in virus internalization. Finally, inhibitors of the sphingolipid biosynthetic pathway efficiently block virion production. PMID:19374198

  17. Human Macrophage SCN5A Activates an Innate Immune Signaling Pathway for Antiviral Host Defense*

    PubMed Central

    Jones, Alexis; Kainz, Danielle; Khan, Faatima; Lee, Cara; Carrithers, Michael D.

    2014-01-01

    Pattern recognition receptors contain a binding domain for pathogen-associated molecular patterns coupled to a signaling domain that regulates transcription of host immune response genes. Here, a novel mechanism that links pathogen recognition to channel activation and downstream signaling is proposed. We demonstrate that an intracellular sodium channel variant, human macrophage SCN5A, initiates signaling and transcription through a calcium-dependent isoform of adenylate cyclase, ADCY8, and the transcription factor, ATF2. Pharmacological stimulation with a channel agonist or treatment with cytoplasmic poly(I:C), a mimic of viral dsRNA, activates this pathway to regulate expression of SP100-related genes and interferon β. Electrophysiological analysis reveals that the SCN5A variant mediates nonselective outward currents and a small, but detectable, inward current. Intracellular poly(I:C) markedly augments an inward voltage-sensitive sodium current and inhibits the outward nonselective current. These results suggest human macrophage SCN5A initiates signaling in an innate immune pathway relevant to antiviral host defense. It is postulated that SCN5A is a novel pathogen sensor and that this pathway represents a channel activation-dependent mechanism of transcriptional regulation. PMID:25368329

  18. CD8 and CD4 Epitope Predictions in RV144: No Strong Evidence of a T-Cell Driven Sieve Effect in HIV-1 Breakthrough Sequences from Trial Participants

    PubMed Central

    Dommaraju, Kalpana; Kijak, Gustavo; Carlson, Jonathan M.; Larsen, Brendan B.; Tovanabutra, Sodsai; Geraghty, Dan E.; Deng, Wenjie; Maust, Brandon S.; Edlefsen, Paul T.; Sanders-Buell, Eric; Ratto-Kim, Silvia; deSouza, Mark S.; Rerks-Ngarm, Supachai; Nitayaphan, Sorachai; Pitisuttihum, Punnee; Kaewkungwal, Jaranit; O'Connell, Robert J.; Robb, Merlin L.; Michael, Nelson L.; Mullins, James I.; Kim, Jerome H.; Rolland, Morgane

    2014-01-01

    The modest protection afforded by the RV144 vaccine offers an opportunity to evaluate its mechanisms of protection. Differences between HIV-1 breakthrough viruses from vaccine and placebo recipients can be attributed to the RV144 vaccine as this was a randomized and double-blinded trial. CD8 and CD4 T cell epitope repertoires were predicted in HIV-1 proteomes from 110 RV144 participants. Predicted Gag epitope repertoires were smaller in vaccine than in placebo recipients (p = 0.019). After comparing participant-derived epitopes to corresponding epitopes in the RV144 vaccine, the proportion of epitopes that could be matched differed depending on the protein conservation (only 36% of epitopes in Env vs 84–91% in Gag/Pol/Nef for CD8 predicted epitopes) or on vaccine insert subtype (55% against CRF01_AE vs 7% against subtype B). To compare predicted epitopes to the vaccine, we analyzed predicted binding affinity and evolutionary distance measurements. Comparisons between the vaccine and placebo arm did not reveal robust evidence for a T cell driven sieve effect, although some differences were noted in Env-V2 (0.022≤p-value≤0.231). The paucity of CD8 T cell responses identified following RV144 vaccination, with no evidence for V2 specificity, considered together both with the association of decreased infection risk in RV 144 participants with V-specific antibody responses and a V2 sieve effect, lead us to hypothesize that this sieve effect was not T cell specific. Overall, our results did not reveal a strong differential impact of vaccine-induced T cell responses among breakthrough infections in RV144 participants. PMID:25350851

  19. Molecular clocks.

    PubMed

    Lee, Michael S Y; Ho, Simon Y W

    2016-05-23

    In the 1960s, several groups of scientists, including Emile Zuckerkandl and Linus Pauling, had noted that proteins experience amino acid replacements at a surprisingly consistent rate across very different species. This presumed single, uniform rate of genetic evolution was subsequently described using the term 'molecular clock'. Biologists quickly realised that such a universal pacemaker could be used as a yardstick for measuring the timescale of evolutionary divergences: estimating the rate of amino acid exchanges per unit of time and applying it to protein differences across a range of organisms would allow deduction of the divergence times of their respective lineages (Figure 1). PMID:27218841

  20. Streptococcal C5a peptidase is a highly specific endopeptidase.

    PubMed Central

    Cleary, P P; Prahbu, U; Dale, J B; Wexler, D E; Handley, J

    1992-01-01

    Compositional analysis of streptococcal C5a peptidase (SCPA) cleavage products from a synthetic peptide corresponding to the 20 C-terminal residues of C5a demonstrated that the target cleavage site is His-Lys rather than Lys-Asp, as previously suggested. A C5a peptide analog with Lys replaced by Gln was also subject to cleavage by SCPA. This confirmed that His-Lys rather than Lys-Asp is the scissile bond. Cleavage at histidine is unusual but is the same as that suggested for a peptidase produced by group B streptococci. Native C5 protein was also resistant to SCPA, suggesting that the His-Lys bond is inaccessible prior to proteolytic cleavage by C5 convertase. These experiments showed that the streptococcal C5a peptidase is highly specific for C5a and suggest that its function is not merely to process protein for metabolic consumption but to act primarily to eliminate this chemotactic signal from inflammatory foci. Images PMID:1452354

  1. A Possible Zebrafish Model of Polycystic Kidney Disease: Knockdown of wnt5a Causes Cysts in Zebrafish Kidneys

    PubMed Central

    Huang, Liwei; Xiao, An; Wecker, Andrea; McBride, Daniel A.; Choi, Soo Young; Zhou, Weibin; Lipschutz, Joshua H.

    2015-01-01

    Polycystic kidney disease (PKD) is one of the most common causes of end-stage kidney disease, a devastating disease for which there is no cure. The molecular mechanisms leading to cyst formation in PKD remain somewhat unclear, but many genes are thought to be involved. Wnt5a is a non-canonical glycoprotein that regulates a wide range of developmental processes. Wnt5a works through the planar cell polarity (PCP) pathway that regulates oriented cell division during renal tubular cell elongation. Defects of the PCP pathway have been found to cause kidney cyst formation. Our paper describes a method for developing a zebrafish cystic kidney disease model by knockdown of the wnt5a gene with wnt5a antisense morpholino (MO) oligonucleotides. Tg(wt1b:GFP) transgenic zebrafish were used to visualize kidney structure and kidney cysts following wnt5a knockdown. Two distinct antisense MOs (AUG - and splice-site) were used and both resulted in curly tail down phenotype and cyst formation after wnt5a knockdown. Injection of mouse Wnt5a mRNA, resistant to the MOs due to a difference in primary base pair structure, rescued the abnormal phenotype, demonstrating that the phenotype was not due to “off-target” effects of the morpholino. This work supports the validity of using a zebrafish model to study wnt5a function in the kidney. PMID:25489842

  2. A possible zebrafish model of polycystic kidney disease: knockdown of wnt5a causes cysts in zebrafish kidneys.

    PubMed

    Huang, Liwei; Xiao, An; Wecker, Andrea; McBride, Daniel A; Choi, Soo Young; Zhou, Weibin; Lipschutz, Joshua H

    2014-12-02

    Polycystic kidney disease (PKD) is one of the most common causes of end-stage kidney disease, a devastating disease for which there is no cure. The molecular mechanisms leading to cyst formation in PKD remain somewhat unclear, but many genes are thought to be involved. Wnt5a is a non-canonical glycoprotein that regulates a wide range of developmental processes. Wnt5a works through the planar cell polarity (PCP) pathway that regulates oriented cell division during renal tubular cell elongation. Defects of the PCP pathway have been found to cause kidney cyst formation. Our paper describes a method for developing a zebrafish cystic kidney disease model by knockdown of the wnt5a gene with wnt5a antisense morpholino (MO) oligonucleotides. Tg(wt1b:GFP) transgenic zebrafish were used to visualize kidney structure and kidney cysts following wnt5a knockdown. Two distinct antisense MOs (AUG - and splice-site) were used and both resulted in curly tail down phenotype and cyst formation after wnt5a knockdown. Injection of mouse Wnt5a mRNA, resistant to the MOs due to a difference in primary base pair structure, rescued the abnormal phenotype, demonstrating that the phenotype was not due to "off-target" effects of the morpholino. This work supports the validity of using a zebrafish model to study wnt5a function in the kidney.

  3. A structural study of Hypocrea jecorina Cel5A.

    PubMed

    Lee, Toni M; Farrow, Mary F; Arnold, Frances H; Mayo, Stephen L

    2011-11-01

    Interest in generating lignocellulosic biofuels through enzymatic hydrolysis continues to rise as nonrenewable fossil fuels are depleted. The high cost of producing cellulases, hydrolytic enzymes that cleave cellulose into fermentable sugars, currently hinders economically viable biofuel production. Here, we report the crystal structure of a prevalent endoglucanase in the biofuels industry, Cel5A from the filamentous fungus Hypocrea jecorina. The structure reveals a general fold resembling that of the closest homolog with a high-resolution structure, Cel5A from Thermoascus aurantiacus. Consistent with previously described endoglucanase structures, the H. jecorina Cel5A active site contains a primarily hydrophobic substrate binding groove and a series of hydrogen bond networks surrounding two catalytic glutamates. The reported structure, however, demonstrates stark differences between side-chain identity, loop regions, and the number of disulfides. Such structural information may aid efforts to improve the stability of this protein for industrial use while maintaining enzymatic activity through revealing nonessential and immutable regions.

  4. A structural study of Hypocrea jecorina Cel5A

    PubMed Central

    Lee, Toni M; Farrow, Mary F; Arnold, Frances H; Mayo, Stephen L

    2011-01-01

    Interest in generating lignocellulosic biofuels through enzymatic hydrolysis continues to rise as nonrenewable fossil fuels are depleted. The high cost of producing cellulases, hydrolytic enzymes that cleave cellulose into fermentable sugars, currently hinders economically viable biofuel production. Here, we report the crystal structure of a prevalent endoglucanase in the biofuels industry, Cel5A from the filamentous fungus Hypocrea jecorina. The structure reveals a general fold resembling that of the closest homolog with a high-resolution structure, Cel5A from Thermoascus aurantiacus. Consistent with previously described endoglucanase structures, the H. jecorina Cel5A active site contains a primarily hydrophobic substrate binding groove and a series of hydrogen bond networks surrounding two catalytic glutamates. The reported structure, however, demonstrates stark differences between side-chain identity, loop regions, and the number of disulfides. Such structural information may aid efforts to improve the stability of this protein for industrial use while maintaining enzymatic activity through revealing nonessential and immutable regions. PMID:21898652

  5. A structural study of Hypocrea jecorina Cel5A.

    PubMed

    Lee, Toni M; Farrow, Mary F; Arnold, Frances H; Mayo, Stephen L

    2011-11-01

    Interest in generating lignocellulosic biofuels through enzymatic hydrolysis continues to rise as nonrenewable fossil fuels are depleted. The high cost of producing cellulases, hydrolytic enzymes that cleave cellulose into fermentable sugars, currently hinders economically viable biofuel production. Here, we report the crystal structure of a prevalent endoglucanase in the biofuels industry, Cel5A from the filamentous fungus Hypocrea jecorina. The structure reveals a general fold resembling that of the closest homolog with a high-resolution structure, Cel5A from Thermoascus aurantiacus. Consistent with previously described endoglucanase structures, the H. jecorina Cel5A active site contains a primarily hydrophobic substrate binding groove and a series of hydrogen bond networks surrounding two catalytic glutamates. The reported structure, however, demonstrates stark differences between side-chain identity, loop regions, and the number of disulfides. Such structural information may aid efforts to improve the stability of this protein for industrial use while maintaining enzymatic activity through revealing nonessential and immutable regions. PMID:21898652

  6. Molecular spintronics.

    PubMed

    Sanvito, Stefano

    2011-06-01

    The electron spin made its debut in the device world only two decades ago but today our ability of detecting the spin state of a moving electron underpins the entire magnetic data storage industry. This technological revolution has been driven by a constant improvement in our understanding on how spins can be injected, manipulated and detected in the solid state, a field which is collectively named Spintronics. Recently a number of pioneering experiments and theoretical works suggest that organic materials can offer similar and perhaps superior performances in making spin-devices than the more conventional inorganic metals and semiconductors. Furthermore they can pave the way for radically new device concepts. This is Molecular Spintronics, a blossoming research area aimed at exploring how the unique properties of the organic world can marry the requirements of spin-devices. Importantly, after a first phase, where most of the research was focussed on exporting the concepts of inorganic spintronics to organic materials, the field has moved to a more mature age, where the exploitation of the unique properties of molecules has begun to emerge. Molecular spintronics now collects a diverse and interdisciplinary community ranging from device physicists to synthetic chemists to surface scientists. In this critical review, I will survey this fascinating, rapidly evolving, field with a particular eye on new directions and opportunities. The main differences and challenges with respect to standard spintronics will be discussed and so will be the potential cross-fertilization with other fields (177 references).

  7. Molecular paleontology.

    PubMed

    Marota, I; Rollo, F

    2002-01-01

    Molecular paleontology, i.e., the recovery of DNA from ancient human, animal, and plant remains is an innovative research field that has received progressively more attention from the scientific community since the 1980s. In the last decade, the field was punctuated by claims which aroused great interest but eventually turned out to be fakes--the most famous being the sequence of dinosaur DNA later shown to be of human origin. At present, the discipline is characterized by some certainties and many doubts. We know, for example, that we have reasonable chances to recover authentic DNA from a mammoth carcass, while our chances are negligible (or nonexistent) in the case of a dynastic mummy from Egypt. On the other hand, though we are developing convincing models of DNA decay in bone, we are not yet able to predict whether a certain paleontological or archeological site will yield material amenable to DNA analysis. This article reviews some of the most important and promising investigations using molecular paleontology approaches, such as studies on the conservation of DNA in human bone, the quest for ancient DNA in permafrost-frozen fauna, the Tyrolean iceman, and the Neandertals.

  8. Molecular Plasmonics.

    PubMed

    Lauchner, Adam; Schlather, Andrea E; Manjavacas, Alejandro; Cui, Yao; McClain, Michael J; Stec, Grant J; García de Abajo, F Javier; Nordlander, Peter; Halas, Naomi J

    2015-09-01

    Graphene supports surface plasmons that have been observed to be both electrically and geometrically tunable in the mid- to far-infrared spectral regions. In particular, it has been demonstrated that graphene plasmons can be tuned across a wide spectral range spanning from the mid-infrared to the terahertz. The identification of a general class of plasmonic excitations in systems containing only a few dozen atoms permits us to extend this versatility into the visible and ultraviolet. As appealing as this extension might be for active nanoscale manipulation of visible light, its realization constitutes a formidable technical challenge. We experimentally demonstrate the existence of molecular plasmon resonances in the visible for ionized polycyclic aromatic hydrocarbons (PAHs), which we reversibly switch by adding, then removing, a single electron from the molecule. The charged PAHs display intense absorption in the visible regime with electrical and geometrical tunability analogous to the plasmonic resonances of much larger nanographene systems. Finally, we also use the switchable molecular plasmon in anthracene to demonstrate a proof-of-concept low-voltage electrochromic device.

  9. Molecular Modeling

    NASA Astrophysics Data System (ADS)

    Holmes, Jon L.

    1999-06-01

    Molecular modeling has trickled down from the realm of pharmaceutical and research laboratories into the realm of undergraduate chemistry instruction. It has opened avenues for the visualization of chemical concepts that previously were difficult or impossible to convey. I am sure that many of you have developed exercises using the various molecular modeling tools. It is the desire of this Journal to become an avenue for you to share these exercises among your colleagues. It is to this end that Ron Starkey has agreed to edit such a column and to publish not only the description of such exercises, but also the software documents they use. The WWW is the obvious medium to distribute this combination and so accepted submissions will appear online as a feature of JCE Internet. Typical molecular modeling exercise: finding conformation energies. Molecular Modeling Exercises and Experiments is the latest feature column of JCE Internet, joining Conceptual Questions and Challenge Problems, Hal's Picks, and Mathcad in the Chemistry Curriculum. JCE Internet continues to seek submissions in these areas of interest and submissions of general interest. If you have developed materials and would like to submit them, please see our Guide to Submissions for more information. The Chemical Education Resource Shelf, Equipment Buyers Guide, and WWW Site Review would also like to hear about chemistry textbooks and software, equipment, and WWW sites, respectively. Please consult JCE Internet Features to learn more about these resources at JCE Online. Email Announcements Would you like to be informed by email when the latest issue of the Journal is available online? when a new JCE Software title is shipping? when a new JCE Internet article has been published or is available for Open Review? when your subscription is about to expire? A new feature of JCE Online makes this possible. Visit our Guestbook to learn how. When

  10. Relevance of the Axis Spermidine/eIF5A for Plant Growth and Development.

    PubMed

    Belda-Palazón, Borja; Almendáriz, Carla; Martí, Esmeralda; Carbonell, Juan; Ferrando, Alejandro

    2016-01-01

    One key role of the essential polyamine spermidine in eukaryotes is to provide the 4-aminobutyl moiety group destined to the post-translational modification of a lysine in the highly conserved translation factor eIF5A. This modification is catalyzed by two sequential enzymatic steps leading to the activation of eIF5A by the conversion of one conserved lysine to the unusual amino acid hypusine. The active translation factor facilitates the sequence-specific translation of polyproline sequences that otherwise cause ribosome stalling. In spite of the well-characterized involvement of active eIF5A in the translation of proline repeat-rich proteins, its biological role has been recently elucidated only in mammals, and it is poorly described at the functional level in plants. Here we describe the alterations in plant growth and development caused by RNAi-mediated conditional genetic inactivation of the hypusination pathway in Arabidopsis thaliana by knocking-down the enzyme deoxyhypusine synthase. We have uncovered that spermidine-mediated activation of eIF5A by hypusination is involved in several aspects of plant biology such as the control of flowering time, the aerial and root architecture, and root hair growth. In addition this pathway is required for adaptation to challenging growth conditions such as high salt and high glucose medium and to elevated concentrations of the plant hormone ABA. We have also performed a bioinformatic analysis of polyproline-rich containing proteins as putative eIF5A targets to uncover their organization in clusters of protein networks to find molecular culprits for the disclosed phenotypes. This study represents a first attempt to provide a holistic view of the biological relevance of the spermidine-dependent hypusination pathway for plant growth and development.

  11. Relevance of the Axis Spermidine/eIF5A for Plant Growth and Development

    PubMed Central

    Belda-Palazón, Borja; Almendáriz, Carla; Martí, Esmeralda; Carbonell, Juan; Ferrando, Alejandro

    2016-01-01

    One key role of the essential polyamine spermidine in eukaryotes is to provide the 4-aminobutyl moiety group destined to the post-translational modification of a lysine in the highly conserved translation factor eIF5A. This modification is catalyzed by two sequential enzymatic steps leading to the activation of eIF5A by the conversion of one conserved lysine to the unusual amino acid hypusine. The active translation factor facilitates the sequence-specific translation of polyproline sequences that otherwise cause ribosome stalling. In spite of the well-characterized involvement of active eIF5A in the translation of proline repeat-rich proteins, its biological role has been recently elucidated only in mammals, and it is poorly described at the functional level in plants. Here we describe the alterations in plant growth and development caused by RNAi-mediated conditional genetic inactivation of the hypusination pathway in Arabidopsis thaliana by knocking-down the enzyme deoxyhypusine synthase. We have uncovered that spermidine-mediated activation of eIF5A by hypusination is involved in several aspects of plant biology such as the control of flowering time, the aerial and root architecture, and root hair growth. In addition this pathway is required for adaptation to challenging growth conditions such as high salt and high glucose medium and to elevated concentrations of the plant hormone ABA. We have also performed a bioinformatic analysis of polyproline-rich containing proteins as putative eIF5A targets to uncover their organization in clusters of protein networks to find molecular culprits for the disclosed phenotypes. This study represents a first attempt to provide a holistic view of the biological relevance of the spermidine-dependent hypusination pathway for plant growth and development. PMID:26973686

  12. Deletion of Inpp5a causes ataxia and cerebellar degeneration in mice.

    PubMed

    Yang, Andy W; Sachs, Andrew J; Nystuen, Arne M

    2015-10-01

    The progressive and permanent loss of cerebellar Purkinje cells (PC) is a hallmark of many inherited ataxias. Mutations in several genes involved in the regulation of Ca(2+) release from intracellular stores by the second messenger IP3 have been associated with PC dysfunction or death. While much is known about the defects in production and response to IP3, less is known about the defects in breakdown of the IP3 second messenger. A mutation in Inpp4a of the pathway is associated with a severe, early-onset PC degeneration in the mouse model weeble. The step preceding the removal of the 4-phosphate is the removal of the 5-phosphate by Inpp5a. Gene expression analysis was performed on an Inpp5a (Gt(OST50073)Lex) mouse generated by gene trap insertion using quantitative real-time PCR (qRT-PCR), immunohistochemistry, and Western blot. Phenotypic analyses were performed using rotarod, β-galactosidase staining, and phosphatase activity assay. Statistical significance was calculated. The deletion of Inpp5a causes an early-onset yet slowly progressive PC degeneration and ataxia. Homozygous mutants (90%) exhibit perinatal lethality; surviving homozygotes show locomotor instability at P16. A consistent pattern of PC loss in the cerebellum is initially detectable by weaning and widespread by P60. Phosphatase activity toward phosphoinositol substrates is reduced in the mutant relative to littermates. The ataxic phenotype and characteristics neurodegeneration of the Inpp5a (Gt(OST50073)Lex) mouse indicate a crucial role for Inpp5a in PC survival. The identification of the molecular basis of the selective PC survival will be important in defining a neuroprotective gene applicable to establishing a disease mechanism.

  13. Wnt5a induces ROR1/ROR2 heterooligomerization to enhance leukemia chemotaxis and proliferation

    PubMed Central

    Yu, Jian; Chen, Liguang; Cui, Bing; Widhopf, George F.; Shen, Zhouxin; Wu, Rongrong; Zhang, Ling; Zhang, Suping; Briggs, Steven P.; Kipps, Thomas J.

    2015-01-01

    Evolutionarily conserved receptor tyrosine kinase–like orphan receptor-1 and -2 (ROR1/2) are considered distinct receptors for Wnt5a and are implicated in noncanonical Wnt signaling in organogenesis and cancer metastasis. We found that Wnt5a enhanced proliferation and migration of chronic lymphocytic leukemia (CLL) cells and that these effects were blocked by the humanized anti-ROR1 mAb cirmtuzumab (UC-961). Treatment of CLL cells with Wnt5a induced ROR1 to oligomerize with ROR2 and recruit guanine exchange factors (GEFs), which activated Rac1 and RhoA; siRNA-mediated silencing of either ROR1 or ROR2 or treatment with UC-961 inhibited these effects. Using the ROR1-deficient CLL cell line MEC1, we demonstrated that ectopic ROR1 expression induced ROR1/ROR2 heterooligomers, which recruited GEFs, and enhanced proliferation, cytokine-directed migration, and engraftment potential of MEC1 cells in immune-deficient mice. Notably, treatment with UC-961 inhibited engraftment of ROR1+ leukemia cells in immune-competent ROR1-transgenic mice. Molecular analysis revealed that the extracellular Kringle domain is required for ROR1/ROR2 heterooligomerization and the cysteine-rich domain or intracellular proline-rich domain is required for Wnt5a-induced recruitment of GEFs to ROR1/ROR2. This study identifies an interaction between ROR1 and ROR2 that is required for Wnt5a signaling that promotes leukemia chemotaxis and proliferation. PMID:26690702

  14. 5 A's Dean's Grant Second Year Monograph. 1980-82.

    ERIC Educational Resources Information Center

    Melnick, Curtis C., Ed.

    The monograph presents 12 papers on aspects of retraining College of Education faculty regarding mainstreaming of handicapped children. Papers grew out of the 5 A's Dean's Grant (Awareness, Access, Appropriateness, Assessment, and Accountability) at Roosevelt University. The following titles and authors are represented: "On Loving the Unlovable"…

  15. Molecular dynamics.

    PubMed

    Cheng, Xiaolin; Ivanov, Ivaylo

    2012-01-01

    Molecular dynamics (MD) simulation holds the promise of revealing the mechanisms of biological processes in their ultimate detail. It is carried out by computing the interaction forces acting on each atom and then propagating the velocities and positions of the atoms by numerical integration of Newton's equations of motion. In this review, we present an overview of how the MD simulation can be conducted to address computational toxicity problems. The study cases will cover a standard MD simulation performed to investigate the overall flexibility of a cytochrome P450 (CYP) enzyme and a set of more advanced MD simulations to examine the barrier to ion conduction in a human α7 nicotinic acetylcholine receptor (nAChR).

  16. Upgradation of bauxite by molecular hydrogen and hydrogen plasma

    NASA Astrophysics Data System (ADS)

    Parhi, B. R.; Sahoo, S. K.; Mishra, S. C.; Bhoi, B.; Paramguru, R. K.; Satapathy, B. K.

    2016-10-01

    An approach was developed to upgrade the bauxite ore by molecular hydrogen and hydrogen plasma. A gibbsite-type bauxite sample was obtained from National Aluminium Company (NALCO), Odisha, India. The obtained sample was crushed and sieved (to 100 μm) prior to the chemical analysis and grain-size distribution study. The bauxite sample was calcined in the temperature range from 500 to 700°C for different time intervals to optimize the conditions for maximum moisture removal. This process was followed by the reduction of the calcined ore by molecular hydrogen and hydrogen plasma. Extraction of alumina from the reduced ore was carried out via acid leaching in chloride media for 2 h at 60°C. X-ray diffraction, scanning electron microscopy, thermogravimetry in conjunction with differential scanning calorimetry, and Fourier transform infrared spectroscopy were used to determine the physicochemical characteristics of the material before and after extraction. Alumina extracted from the reduced ore at the optimum calcination temperature of 700°C and the optimum calcination time of 4 h is found to be 90% pure.

  17. International Conference on Harmonisation; guidance on Q4B Evaluation and Recommendation of Pharmacopoeial texts for use in the International Conference on Harmonisation Regions; Annex 12 on Analytical Sieving General Chapter; availability. Notice.

    PubMed

    2010-09-01

    The Food and Drug Administration (FDA) is announcing the availability of a guidance entitled "Q4B Evaluation and Recommendation of Pharmacopoeial Texts for Use in the ICH Regions; Annex 12: Analytical Sieving General Chapter." The guidance was prepared under the auspices of the International Conference on Harmonisation of Technical Requirements for Registration of Pharmaceuticals for Human Use (ICH). The guidance provides the results of the ICH Q4B evaluation of the Analytical Sieving General Chapter harmonized text from each of the three pharmacopoeias (United States, European, and Japanese) represented by the Pharmacopoeial Discussion Group (PDG). The guidance conveys recognition of the three pharmacopoeial methods by the three ICH regulatory regions and provides specific information regarding the recognition. The guidance is intended to recognize the interchangeability between the local regional pharmacopoeias, thus avoiding redundant testing in favor of a common testing strategy in each regulatory region. This guidance is in the form of an annex to the core guidance on the Q4B process entitled "Q4B Evaluation and Recommendation of Pharmacopoeial Texts for Use in the ICH Regions" (the core ICH Q4B guidance).

  18. Progress on New Hepatitis C Virus Targets: NS2 and NS5A

    NASA Astrophysics Data System (ADS)

    Marcotrigiano, Joseph

    Hepatitis C virus (HCV) is a major global health problem, affecting about 170 million people worldwide. Chronic infection can lead to cirrhosis and liver cancer. The replication machine of HCV is a multi-subunit membrane associated complex, consisting of nonstructural proteins (NS2-5B), which replicate the viral RNA genome. The structures of NS5A and NS2 were recently determined. NS5A is an essential replicase component that also modulates numerous cellular processes ranging from innate immunity to cell growth and survival. The structure reveals a novel protein fold, a new zinc coordination motif, a disulfide bond and a dimer interface. Analysis of molecular surfaces suggests the location of the membrane interaction surface of NS5A, as well as hypothetical protein and RNA binding sites. NS2 is one of two virally encoded proteases that are required for processing the viral polyprotein into the mature nonstructural proteins. NS2 is a dimeric cysteine protease with two composite active sites. For each active site, the catalytic histidine and glutamate residues are contributed by one monomer and the nucleophilic cysteine by the other. The C-terminal residues remain coordinated in the two active sites, predicting an inactive post-cleavage form. The structure also reveals possible sites of membrane interaction, a rare cis-proline residue, and highly conserved dimer contacts. The novel features of both structures have changed the current view of HCV polyprotein replication and present new opportunities for antiviral drug design.

  19. A novel missense mutation of COL5A2 in a patient with Ehlers–Danlos syndrome

    PubMed Central

    Watanabe, Miki; Nakagawa, Ryuji; Naruto, Takuya; Kohmoto, Tomohiro; Suga, Ken-ichi; Goji, Aya; Kagami, Shoji; Masuda, Kiyoshi; Imoto, Issei

    2016-01-01

    Ehlers–Danlos syndrome (EDS) is a group of inherited connective tissue disorders characterized by hyperextensible skin, joint hypermobility and soft tissue fragility. For molecular diagnosis, targeted exome sequencing was performed on a 9-year-old male patient who was clinically suspected to have EDS. The patient presented with progressive kyphoscoliosis, joint hypermobility and hyperextensible skin without scars. Ultimately, classical EDS was diagnosed by identifying a novel, mono-allelic mutation in COL5A2 [NM_000393.3(COL5A2_v001):c.682G>A, p.Gly228Arg]. PMID:27656288

  20. A novel missense mutation of COL5A2 in a patient with Ehlers-Danlos syndrome.

    PubMed

    Watanabe, Miki; Nakagawa, Ryuji; Naruto, Takuya; Kohmoto, Tomohiro; Suga, Ken-Ichi; Goji, Aya; Kagami, Shoji; Masuda, Kiyoshi; Imoto, Issei

    2016-01-01

    Ehlers-Danlos syndrome (EDS) is a group of inherited connective tissue disorders characterized by hyperextensible skin, joint hypermobility and soft tissue fragility. For molecular diagnosis, targeted exome sequencing was performed on a 9-year-old male patient who was clinically suspected to have EDS. The patient presented with progressive kyphoscoliosis, joint hypermobility and hyperextensible skin without scars. Ultimately, classical EDS was diagnosed by identifying a novel, mono-allelic mutation in COL5A2 [NM_000393.3(COL5A2_v001):c.682G>A, p.Gly228Arg]. PMID:27656288

  1. A novel missense mutation of COL5A2 in a patient with Ehlers–Danlos syndrome

    PubMed Central

    Watanabe, Miki; Nakagawa, Ryuji; Naruto, Takuya; Kohmoto, Tomohiro; Suga, Ken-ichi; Goji, Aya; Kagami, Shoji; Masuda, Kiyoshi; Imoto, Issei

    2016-01-01

    Ehlers–Danlos syndrome (EDS) is a group of inherited connective tissue disorders characterized by hyperextensible skin, joint hypermobility and soft tissue fragility. For molecular diagnosis, targeted exome sequencing was performed on a 9-year-old male patient who was clinically suspected to have EDS. The patient presented with progressive kyphoscoliosis, joint hypermobility and hyperextensible skin without scars. Ultimately, classical EDS was diagnosed by identifying a novel, mono-allelic mutation in COL5A2 [NM_000393.3(COL5A2_v001):c.682G>A, p.Gly228Arg].

  2. Unique aspects of pain reduction in osteoarthritis of the knee with LMWF-5A

    PubMed Central

    McGrath, Brian

    2015-01-01

    Osteoarthritis of the knee (OAK) is a common form of arthritis that can lead to substantial pain and disability. This commentary highlights key aspects of the recently published phase 3 A Efficacy and Safety Study of Two Doses of Intra-Articular Injection of Ampion™ in Adults With Pain Due to Osteoarthritis of the Knee (SPRING) study. SPRING (NCT01839331) was a multicenter, randomized, vehicle-controlled, double-blind trial that evaluated the safety and efficacy of the low-molecular-weight fraction of 5% human serum albumin (LMWF-5A) for treatment of pain, measured by the Western Ontario and McMaster Universities Osteoarthritis (WOMAC) pain scale, in patients with symptomatic OAK (N=329). Patients in this study reflected many characteristics of “real-world” individuals with OAK, with a broad range of disease severity and disability. The most important finding from this study was that treatment with a single intra-articular injection of LMWF-5A led to significant pain reduction in the patients with objective radiographic evidence of severe disease and joint deterioration (Kellgren-Lawrence grade 3; P=0.04 and Kellgren-Lawrence grade 4; P=0.02). The magnitude of pain reduction in the entire cohort treated with LMWF-5A was 42% from baseline and the treatment effect compared with vehicle control (estimated difference in WOMAC pain, −0.25; P=0.004) was also notable, especially relative to a previously reported study of hyaluronic acid, in which only a marginally significant treatment effect was observed (mean difference in WOMAC pain compared with control, −0.15; P=0.047). Significant improvement in physical function observed with LMWF-5A (P=0.04) was also noted and suggests that LMWF-5A may provide therapeutic benefit for those who are limited in the activities of daily living. Intra-articular injection of LMWF-5A was well tolerated, and the adverse event profile was similar to that of control. These results demonstrate significant benefit of LMWF-5A for

  3. Transonic buffet behavior of Northrop F-5A aircraft

    NASA Technical Reports Server (NTRS)

    Hwang, C.; Pi, W. S.

    1975-01-01

    Flight tests were performed on an extensively instrumented F-5A aircraft to investigate the dynamic buffet pressure distribution on the wing surfaces and the responses during a series of transonic maneuvers called the windup turns. The maneuvers to maximum lift were performed at three Mach number-altitude combinations with a constant 'q' of approximately 14,360 N/sq m (300 psf). The fluctuating buffet pressure data at 24 stations on the right wing of the F-5A were acquired by miniaturized semiconductor type pressure transducers mounted on the wing. A new transducer mounting and wiring technique was applied where the interference with the natural flow condition was minimized. The data acquired in this manner were found adequate to trace the shock origin, the movement of the shock front and the development of the separated flow (shock induced or leading edge induced) on the wing surface.

  4. Calcium and cargoes as regulators of myosin 5a activity

    SciTech Connect

    Sellers, James R. Thirumurugan, Kavitha; Sakamoto, Takeshi; Hammer, John A.; Knight, Peter J.

    2008-04-25

    Myosin 5a is a two-headed actin-dependent motor that transports various cargoes in cells. Its enzymology and mechanochemistry have been extensively studied in vitro. It is a processive motor that takes multiple 36 nm steps on actin. The enzymatic activity of myosin 5 is regulated by an intramolecular folding mechanism whereby its lever arms fold back against the coiled-coil tail such that the motor domains directly bind the globular tail domains. We show that the structure seen in individual folded molecules is consistent with electron density map of two-dimensional crystals of the molecule. In this compact state, the actin-activated MgATPase activity of the molecule is markedly inhibited and the molecule cannot move processively on surface bound actin filaments. The actin-activated MgATPase activity of myosin 5a is activated by increasing the calcium concentration or by binding of a cargo-receptor molecule, melanophilin, in vitro. However, calcium binding to the calmodulin light chains results in dissociation of some of the calmodulin which disrupts the ability of myosin 5a to move on actin filaments in vitro. Thus we propose that the physiologically relevant activation pathway in vivo involves binding of cargo-receptor proteins.

  5. Zeolitic imidazolate framework-8 as a reverse osmosis membrane for water desalination: insight from molecular simulation.

    PubMed

    Hu, Zhongqiao; Chen, Yifei; Jiang, Jianwen

    2011-04-01

    A molecular simulation study is reported for water desalination in zeolitic imidazolate framework-8 (ZIF-8) membrane. The simulation demonstrates that water desalination occurs under external pressure, and Na(+) and Cl(-) ions cannot transport across the membrane due to the sieving effect of small apertures in ZIF-8. The flux of water permeating the membrane scales linearly with the external pressure, and exhibits an Arrhenius-type relation with temperature (activation energy of 24.4 kJ∕mol). Compared with bulk phase, water molecules in ZIF-8 membrane are less hydrogen-bonded and the lifetime of hydrogen-bonding is considerably longer, as attributed to the surface interactions and geometrical confinement. This simulation study suggests that ZIF-8 might be potentially used as a reverse osmosis membrane for water purification.

  6. Molecular Electronic Terms and Molecular Orbital Configurations.

    ERIC Educational Resources Information Center

    Mazo, R. M.

    1990-01-01

    Discussed are the molecular electronic terms which can arise from a given electronic configuration. Considered are simple cases, molecular states, direct products, closed shells, and open shells. Two examples are provided. (CW)

  7. The NPG 7120.5A Electronic Review Process

    NASA Technical Reports Server (NTRS)

    McBrayer, Robert; Ives, Mark

    1998-01-01

    The use of electronics to review a document is well within the technical realm of today's state-of-the-art workplace. File servers and web site interaction are common tools for many NASA employees. The electronic comment processing described here was developed for the NPG 7120.5A review to augment the existing NASA Online Directives Information System (NODIS). The NODIS system is NASA's official system for formal review, approval and storage of NASA Directives. The electronic review process worked so well that NASA and other agencies may want to consider it as one of our "best practices." It was participatory decision making at its very best, a process that attracted dozens of very good ideas to improve the document as well as the way we can be managing projects far more effectively. The revision of NPG 7120.5A has significant implications for the way all elements of the Agency accomplish program and project management. Therefore, the review of NPG 7120.5A was an Agencywide effort with high visibility, heavy participation and a short schedule. The level of involvement created interest in supplementing the formal NODIS system with a system to collect comments efficiently and to allow the Centers and Codes to review and consolidate their comments into the official system in a short period of time. In addition, the Program Management Council Working Group (PMCWG), responsible for the revision of the document and the disposition of official comments, needed an electronic system to manage the disposition of comments, obtain PMCWG consensus on each disposition, and coordinate the disposition with the appropriate Headquarters Code that had submitted the official comment. The combined NASA and contractor talents and resources provided a system that supplemented the NODIS system and its operating personnel to produce a thorough review and approval of NPG 7120.5A on April 3, 1998, 7.5 months from the start of the process. The original six-month schedule is indicated. All

  8. Assaying Wnt5A-mediated invasion in melanoma cells.

    PubMed

    O'Connell, Michael P; French, Amanda D; Leotlela, Poloko D; Weeraratna, Ashani T

    2008-01-01

    Wnt5A has been implicated in melanoma metastasis, and the progression of other cancers including pancreatic, gastric, prostate, and lung cancers. Assays to test motility and invasion include both in vivo assays and in vitro assays. The in vivo assays include the use of tail vein or footpad injections of metastatic cells, and are often laborious and expensive. In vitro invasion assays provide quick readouts that can help to establish conditions that either activate or inhibit melanoma cell motility, and to assess whether the conditions in question are worth translating into an in vivo model. Here we describe two standard methods for assaying motility and invasion in vitro including wound healing assays and Matrigel invasion assays (Boyden chamber assays). In addition, we and several other laboratories have previously shown that melanoma cells require matrix metalloproteinase (MMP)-2 for their invasion, and have recently shown that Wnt5A treatment can increase the levels of this enzyme in melanoma cells, as demonstrated by gelatin zymography. The use of these techniques can help to assess the migratory capacity of melanoma cells in response to Wnt treatment.

  9. The molecular matching problem

    NASA Technical Reports Server (NTRS)

    Kincaid, Rex K.

    1993-01-01

    Molecular chemistry contains many difficult optimization problems that have begun to attract the attention of optimizers in the Operations Research community. Problems including protein folding, molecular conformation, molecular similarity, and molecular matching have been addressed. Minimum energy conformations for simple molecular structures such as water clusters, Lennard-Jones microclusters, and short polypeptides have dominated the literature to date. However, a variety of interesting problems exist and we focus here on a molecular structure matching (MSM) problem.

  10. Is HDF5 a Good Format to Replace UVFITS?

    NASA Astrophysics Data System (ADS)

    Price, D. C.; Barsdell, B. R.; Greenhill, L. J.

    2015-09-01

    The FITS (Flexible Image Transport System) data format was developed in the late 1970s for storage and exchange of astronomy-related image data. Since then, it has become a standard file format not only for images, but also for radio interferometer data (e.g. UVFITS, FITS-IDI). But is FITS the right format for next-generation telescopes to adopt? The newer Hierarchical Data Format (HDF5) file format offers considerable advantages over FITS, but has yet to gain widespread adoption within the radio astronomy. One of the major holdbacks is that HDF5 is not well supported by data reduction software packages. Here, we present a comparison of FITS, HDF5, and the MeasurementSet (MS) format for storage of interferometric data. In addition, we present a tool for converting between formats. We show that the underlying data model of FITS can be ported to HDF5, a first step toward achieving wider HDF5 support.

  11. Evaluation of Recharge Potential at Crater U5a (WISHBONE)

    SciTech Connect

    Richard H. French; Samuel L. Hokett

    1998-11-01

    Radionuclides are present both below and above the water table at the Nevada Test Site (NTS), as the result of underground nuclear testing. Mobilization and transport of radionuclides from the vadose zone is a complex process that is influenced by the solubility and sorption characteristics of the individual radionuclides, as well as the soil water flux. On the NTS, subsidence craters resulting from testing underground nuclear weapons are numerous, and many intercept surface water flows. Because craters collect surface water above the sub-surface point of device detonation, these craters may provide a mechanism for surface water to recharge the groundwater aquifer system underlying the NTS. Given this situation, there is a potential for the captured water to introduce contaminants into the groundwater system. Crater U5a (WISHBONE), located in Frenchman Flat, was selected for study because of its potentially large drainage area, and significant erosional features, which suggested that it has captured more runoff than other craters in the Frenchman Flat area. Recharge conditions were studied in subsidence crater U5a by first drilling boreholes and analyzing the collected soil cores to determine the soil properties and moisture conditions. This information, coupled with a 32-year precipitation record, was used to conduct surface and vaodse zone modeling. Surface water modeling predicted that approximately 13 ponding events had occurred during the life of the crater. Vadose zone modeling indicated that since the crater's formation approximately 5,900 m3 of water were captured by the crater. Of this total, approximately 5,200 m3 of potential recahrge may have occurred, and the best estimates of annual average potential recharge rates lie between 36 and 188 cm of water per year. The term potential is used here to indicate that the water is not technically recharged because it has not yet reached the water table.

  12. Cryogenic separation of hydrogen isotopes in single-walled carbon and boron-nitride nanotubes: insight into the mechanism of equilibrium quantum sieving in quasi-one-dimensional pores.

    PubMed

    Kowalczyk, Piotr; Gauden, Piotr A; Terzyk, Artur P

    2008-07-17

    Quasi-one-dimensional cylindrical pores of single-walled boron nitride and carbon nanotubes efficiently differentiate adsorbed hydrogen isotopes at 33 K. Extensive path integral Monte Carlo simulations revealed that the mechanisms of quantum sieving for both types of nanotubes are quantitatively similar; however, the stronger and heterogeneous external solid-fluid potential generated from single-walled boron nitride nanotubes enhanced the selectivity of deuterium over hydrogen both at zero coverage and at finite pressures. We showed that this enhancement of the D(2)/H(2) equilibrium selectivity results from larger localization of hydrogen isotopes in the interior space of single-walled boron nitride nanotubes in comparison to that of equivalent single-walled carbon nanotubes. The operating pressures for efficient quantum sieving of hydrogen isotopes are strongly depending on both the type as well as the size of the nanotube. For all investigated nanotubes, we predicted the occurrence of the minima of the D(2)/H(2) equilibrium selectivity at finite pressure. Moreover, we showed that those well-defined minima are gradually shifted upon increasing of the nanotube pore diameter. We related the nonmonotonic shape of the D(2)/H(2) equilibrium selectivity at finite pressures to the variation of the difference between the average kinetic energy computed from single-component adsorption isotherms of H(2) and D(2). In the interior space of both kinds of nanotubes hydrogen isotopes formed solid-like structures (plastic crystals) at 33 K and 10 Pa with densities above the compressed bulk para-hydrogen at 30 K and 30 MPa.

  13. Bitterness of glucose/galactose: novel mutations in the SLC5A1 gene.

    PubMed

    Pode-Shakked, Ben; Reish, Orit; Aktuglu-Zeybek, Cigdem; Kesselman, Dafna; Dekel, Benjamin; Bujanover, Yoram; Anikster, Yair

    2014-01-01

    Glucose galactose malabsorption (GGM) is a rare autosomal recessive disorder characterized by life-threatening osmotic diarrhea at infancy. When the intake of the offending sugars (namely, glucose, galactose and lactose) is ceased, the diarrhea promptly stops. Mutations in the SLC5A1 gene, encoding the sodium-glucose co-transporter located in the brush border of enterocytes, have been shown to cause the disease. More than 300 subjects of diverse origin have been reported worldwide, most of whom are a result of a consanguineous union. We examined 6 patients from 4 families presenting with complaints consistent with GGM and responsive to the appropriate fructose-based diet. Genomic DNA of the patients was polymerase chain reaction amplified for each of the 15 exons of the SLC5A1 gene and analyzed by nucleotide sequencing. The analysis lead to the identification of 2 novel mutations: a 1915 del C mutation, a frameshift mutation leading to a premature stop at codon 645; and a substitution missense mutation of T to C on nucleotide 947 (exon 9) causing a L316P substitution. In addition, G426R and C255W mutations previously described were identified; in both cases, the patients were shown to be homozygous and their parents heterozygous for the mutation. Of note, additional patients who underwent a similar evaluation at our center for suspected GGM did not show mutations in the SLC5A1 gene. Because the latter did not previously undergo a diagnostic algorithm in full, for instance, one that may consist of a glucose breath hydrogen test and an empiric attempt of a dietary switch to galactomin, we suggest that molecular genotyping of such patients should only follow such appropriate clinical evaluation. PMID:24048166

  14. Dengue virus RNA polymerase NS5: a potential therapeutic target?

    PubMed

    Rawlinson, Stephen M; Pryor, Melinda J; Wright, Peter J; Jans, David A

    2006-12-01

    Dengue fever (DF)/dengue haemorrhagic fever (DHF) is the most common arthropod-borne viral infection, where it is now estimated that 2.5-3 billion people world-wide are at risk of infection. Currently there is no available treatment, in the form of vaccine or drug, making eradication of the mosquito vector the only viable control measure, which has proved costly and of limited success. There are a number of different vaccines undergoing testing, but whilst a dengue vaccine is clearly desirable, there are several issues which make live-attenuated vaccines problematic. These include the phenomenon of antibody-dependent enhancement (ADE) and the possibility of recombination of attenuated vaccine strains with wild-type flavivirus members reverting vaccines to a virulent form. Until we gain a better understanding of these issues and their associated risks, the safety of any live dengue vaccine cannot be assured. It therefore may be safer and more feasible for therapeutic-based approaches to be developed as an alternative to live vaccines. As our understanding of dengue molecular biology expands, new potential targets for drugs are emerging. One of the most promising is the dengue non-structural protein 5 (NS5), the largest and most highly conserved of the dengue proteins. This review examines the unique properties of NS5, including its functions, interactions, subcellular localisation and regulation, and looks at ways in which some of these may be exploited in our quest for effective drugs.

  15. Synthesis and physicochemical properties of Zr-MCM-41 mesoporous molecular sieves and Pt/H{sub 3}PW{sub 12}O{sub 40}/Zr-MCM-41 catalysts

    SciTech Connect

    Chen, L.F. Wang, J.A.; Norena, L.E.; Aguilar, J.; Navarrete, J.; Salas, P.; Montoya, J.A.; Del Angel, P.

    2007-10-15

    For the first time, modifications of the surface and framework of Si-MCM-41 by depositing a heteropolyacid on the surface and by introducing foreign Zr{sup 4+} ions into the framework are investigated. The Zr-modified Si-MCM-41 mesoporous materials (hereafter referred as WSZn, n=Si/Zr=25, 15, 8, 4) were synthesized through a surfactant-templated preparation approach, using low-cost fumed silica as the Si precursor. After impregnation with 25 wt% of H{sub 3}PW{sub 12}O{sub 40}, the surface Broensted acidity of the Pt/H{sub 3}PW{sub 12}O{sub 40}/WSZn catalysts was greatly enhanced by 2-10 times relative to the bare WSZn support. Two kinds of supported heteropolyacids were formed: (i) bulk-like heteropolyacid crystals with unchanged Keggin structures, and (ii) highly dispersed heteropolyacid with distorted Keggin units. The formation of various kinds of heteropolyacid structures is closely related to the interaction between the heteropolyanions and the hydroxyl groups in the host support. - Graphical abstract: Modifications of the surface and framework of Si-MCM-41 by depositing a heteropolyacid on the surface and by introducing foreign Zr{sup 4+} ions into the framework are investigated. Broensted acidity of the Pt/H{sub 3}PW{sub 12}O{sub 40}/Zr-MCM-41 catalysts was greatly enhanced by 2-10 times relative to the bare Zr-MCM-41 support.

  16. Determination of 2-5A synthetase and 2-5A phosphodiesterase in neuroblastoma cells by analytical capillary isotachophoresis: effects of cytokines and comparison with radioenzymatic methods.

    PubMed

    Bruchelt, G; Büdenbender, M; Schmidt, K H; Birk, A; Treuner, J; Niethammer, D

    1994-01-01

    2-5A Synthetase and 2-5A phosphodiesterase were determined by analytical capillary isotachophoresis in comparison to radioenzymatic methods. By means of isotachophoretic analysis, a frequently used radioenzymatic 2-5A synthetase assay was optimized and the results of both assays were compared. Using the isotachophoretic assay the influence of interferon-related cytokines (tumor necrosis factor-alpha and interleukin-2) on 2-5A synthetase induction in neuroblastoma cells was estimated. In contrast to mononuclear blood cells, the tumor necrosis factor induced 2-5A synthetase in these cells. 2-5A Phosphodiesterase was determined using an isotachophoretic assay and a radioenzymatic method. Degradation of A2'p5'A2'p5'A (trimeric form of 2-5A core) was measured by isotachophoresis whereas degradation of a mixture of phosphorus-32 labeled 2-5A cores was registered by radioenzymatic assay. Activity of 2-5A phosphodiesterase was only insignificantly enhanced by interferon in mononuclear blood and neuroblastoma cells. In contrast to the radioenzymatic assays, an accurate determination of 2-5A synthetase as well as of 2-5A phosphodiesterase is possible using the isotachophoretic method because the reactions are followed by measuring the substrates ATP and A2'p5'A2'p5'A, respectively.

  17. A Proline-Tryptophan Turn in the Intrinsically Disordered Domain 2 of NS5A Protein Is Essential for Hepatitis C Virus RNA Replication*

    PubMed Central

    Dujardin, Marie; Madan, Vanesa; Montserret, Roland; Ahuja, Puneet; Huvent, Isabelle; Launay, Helene; Leroy, Arnaud; Bartenschlager, Ralf; Penin, François; Lippens, Guy; Hanoulle, Xavier

    2015-01-01

    Hepatitis C virus (HCV) nonstructural protein 5A (NS5A) and its interaction with the human chaperone cyclophilin A are both targets for highly potent and promising antiviral drugs that are in the late stages of clinical development. Despite its high interest in regards to the development of drugs to counteract the worldwide HCV burden, NS5A is still an enigmatic multifunctional protein poorly characterized at the molecular level. NS5A is required for HCV RNA replication and is involved in viral particle formation and regulation of host pathways. Thus far, no enzymatic activity or precise molecular function has been ascribed to NS5A that is composed of a highly structured domain 1 (D1), as well as two intrinsically disordered domains 2 (D2) and 3 (D3), representing half of the protein. Here, we identify a short structural motif in the disordered NS5A-D2 and report its NMR structure. We show that this structural motif, a minimal Pro314–Trp316 turn, is essential for HCV RNA replication, and its disruption alters the subcellular distribution of NS5A. We demonstrate that this Pro-Trp turn is required for proper interaction with the host cyclophilin A and influences its peptidyl-prolyl cis/trans isomerase activity on residue Pro314 of NS5A-D2. This work provides a molecular basis for further understanding of the function of the intrinsically disordered domain 2 of HCV NS5A protein. In addition, our work highlights how very small structural motifs present in intrinsically disordered proteins can exert a specific function. PMID:26085105

  18. HMGN2 inducibly binds a novel transactivation domain in nuclear PRLr to coordinate Stat5a-mediated transcription.

    PubMed

    Fiorillo, Alyson A; Medler, Terry R; Feeney, Yvonne B; Liu, Yi; Tommerdahl, Kalie L; Clevenger, Charles V

    2011-09-01

    The direct actions of transmembrane receptors within the nucleus remain enigmatic. In this report, we demonstrate that the prolactin receptor (PRLr) localizes to the nucleus where it functions as a coactivator through its interactions with the latent transcription factor signal transducer and activator of transcription 5a (Stat5a) and the high-mobility group N2 protein (HMGN2). We identify a novel transactivation domain within the PRLr that is activated by ligand-induced phosphorylation, an event coupled to HMGN2 binding. The association of the PRLr with HMGN2 enables Stat5a-responsive promoter binding, thus facilitating transcriptional activation and promoting anchorage-independent growth. We propose that HMGN2 serves as a critical regulatory factor in Stat5a-driven gene expression by facilitating the assembly of PRLr/Stat5a onto chromatin and that these events may serve to promote biological events that contribute to a tumorigenic phenotype. Our data imply that phosphorylation may be the molecular switch that activates a cell surface receptor transactivation domain, enabling it to tether chromatin-modifying factors, such as HMGN2, to target promoter regions in a sequence-specific manner.

  19. Identification of two novel KIF5A mutations in hereditary spastic paraplegia associated with mild peripheral neuropathy.

    PubMed

    López, Eva; Casasnovas, Carlos; Giménez, Javier; Santamaría, Raúl; Terrazas, Jesús M; Volpini, Víctor

    2015-11-15

    Spastic paraplegia type 10 (SPG10) is a rare form of autosomal dominant hereditary spastic paraplegia (AD-HSP) due to mutations in KIF5A, a gene encoding the neuronal kinesin heavy-chain involved in axonal transport. KIF5A mutations have been associated with a wide clinical spectrum, ranging from pure HSP to isolated peripheral nerve involvement or complicated HSP phenotypes. Most KIF5A mutations are clustered in the motor domain of the protein that is necessary for microtubule interaction. Here we describe two Spanish families with an adult onset complicated AD-HSP in which neurological studies revealed a mild sensory neuropathy. Intention tremor was also present in both families. Molecular genetic analysis identified two novel mutations c.773 C>T and c.833 C>T in the KIF5A gene resulting in the P258L and P278L substitutions respectively. Both were located in the highly conserved kinesin motor domain of the protein which has previously been identified as a hot spot for KIF5A mutations. This study adds to the evidence associating the known occurrence of mild peripheral neuropathy in the adult onset SPG10 type of AD-HSP. PMID:26403765

  20. Identification of two novel KIF5A mutations in hereditary spastic paraplegia associated with mild peripheral neuropathy.

    PubMed

    López, Eva; Casasnovas, Carlos; Giménez, Javier; Santamaría, Raúl; Terrazas, Jesús M; Volpini, Víctor

    2015-11-15

    Spastic paraplegia type 10 (SPG10) is a rare form of autosomal dominant hereditary spastic paraplegia (AD-HSP) due to mutations in KIF5A, a gene encoding the neuronal kinesin heavy-chain involved in axonal transport. KIF5A mutations have been associated with a wide clinical spectrum, ranging from pure HSP to isolated peripheral nerve involvement or complicated HSP phenotypes. Most KIF5A mutations are clustered in the motor domain of the protein that is necessary for microtubule interaction. Here we describe two Spanish families with an adult onset complicated AD-HSP in which neurological studies revealed a mild sensory neuropathy. Intention tremor was also present in both families. Molecular genetic analysis identified two novel mutations c.773 C>T and c.833 C>T in the KIF5A gene resulting in the P258L and P278L substitutions respectively. Both were located in the highly conserved kinesin motor domain of the protein which has previously been identified as a hot spot for KIF5A mutations. This study adds to the evidence associating the known occurrence of mild peripheral neuropathy in the adult onset SPG10 type of AD-HSP.