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Sample records for stabilizing active site

  1. Active serine involved in the stabilization of the active site loop in the Humicola lanuginosa lipase

    DEFF Research Database (Denmark)

    Peters, Günther H.j.; Svendsen, A.; Langberg, H.

    1998-01-01

    , whereas only small changes are observed for I-Ill suggesting that the active site Lid in the latter opens more easily and hence more lipase molecules are bound to the liposomes. These observations are in agreement with molecular dynamics simulations and subsequent essential dynamics analyses. The results...

  2. Optimal allosteric stabilization sites using contact stabilization analysis.

    Science.gov (United States)

    Dickson, Alex; Bailey, Christopher T; Karanicolas, John

    2017-06-05

    Proteins can be destabilized by a number of environmental factors such as temperature, pH, and mutation. The ability to subsequently restore function under these conditions by adding small molecule stabilizers, or by introducing disulfide bonds, would be a very powerful tool, but the physical principles that drive this stabilization are not well understood. The first problem lies is in choosing an appropriate binding site or disulfide bond location to best confer stability to the active site and restore function. Here, we present a general framework for predicting which allosteric binding sites correlate with stability in the active site. Using the Karanicolas-Brooks Gō-like model, we examine the dynamics of the enzyme β-glucuronidase using an Umbrella Sampling method to thoroughly sample the conformational landscape. Each intramolecular contact is assigned a score termed a "stabilization factor" that measures its correlation with structural changes in the active site. We have carried out this analysis for three different scaling strengths for the intramolecular contacts, and we examine how the calculated stabilization factors depend on the ensemble of destabilized conformations. We further examine a locally destabilized mutant of β-glucuronidase that has been characterized experimentally, and show that this brings about local changes in the stabilization factors. We find that the proximity to the active site is not sufficient to determine which contacts can confer active site stability. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

  3. Site selection of active damper for stabilizing power electronics based power distribution system

    DEFF Research Database (Denmark)

    Yoon, Changwoo; Wang, Xiongfei; Bak, Claus Leth

    2015-01-01

    Stability in the nowadays distribution power system is endangered by interaction problems that may arise from newly added power-electronics based power devices. Recently, a new concept to deal with this higher frequency instability, the active damper, has been proposed. The active damper is a power...... point when the system has many nodes. Therefore, this paper addresses the proper placement of an active damper in an unstable small-scale power distribution system. A time-domain model of the Cigre benchmark low-vltage network is used as a test field. The result shows the active damper location...... electronics based power device, which provides an adjustable damping capability to the power system where the voltage harmonic instability is measured. It can stabilize by adjusting the equivalent node impedance with its plug and play feature. This feature gives many degrees of freedom of its installation...

  4. Encapsulation and Nano-Encapsulation of Papain Active Sites to Enhance Radiolityc Stability and Decrease Toxicity

    International Nuclear Information System (INIS)

    Lugão, A.B.; Varca, G.H.C.; Mathor, M.B.; Santos Lopes, P.; Rogero, M.S.S.; Rogero, J.R.

    2010-01-01

    Papain is used as an ingredient in various enzymatic debridement preparations. Those paste-like preparations are based on water solution and usually are sterilized by radiation. As a consequence, there is a major decrease in papain activity. Papain containing preparations are used in chronic wounds treatment in order to clean and remove the necrotic tissue. However FDA (2008) is taking an action against such products due to severe adverse events reported in patients submitted to papain treatments. Thus, the main goal of this proposal is to develop encapsulated papain containing membranes based on hydrogels and silicone rubber in an attempt to achieve a controllable distribution of size and delivery profile, a toxicity reduction and provide stability towards radiation processing through molecular encapsulation with β-cyclodextrin, which may also provide protection to the enzyme against radiation induced radiolysis. (author)

  5. Encapsulation and Nano-Encapsulation of Papain Active Sites to Enhance Radiolityc Stability and Decrease Toxicity

    International Nuclear Information System (INIS)

    Lugão, A.B.; Varca, G.H.C.; Paiffer, F.; Mathor, M.B.; Lopes, P.S.; Rogero, S.; Rogero, J.R.

    2009-01-01

    Papain is used as an ingredient in various enzymatic debridement preparations. Those paste-like preparations are based on water solution and usually are sterilized by radiation. As a consequence, there is a major decrease in papain activity. Papain containing preparations are used in chronic wounds treatment in order to clean and remove the necrotic tissue. However FDA (2008) is taking an action against such products due to severe adverse events reported in patients which were submitted to papain treatments. Thus, the main goal of this proposal is to develop encapsulated papain containing membranes based on hydrogels and silicone rubber in an attempt to achieve a controllable distribution of size and delivery profile, a toxicity reduction and provide stability towards radiation processing through nanoencapsulation with cyclodextrins, which may also provide protection to the enzyme against radiation induced radiolysis. (author)

  6. Effects of metal ions on stability and activity of hyperthermophilic pyrolysin and further stabilization of this enzyme by modification of a Ca2+-binding site.

    Science.gov (United States)

    Zeng, Jing; Gao, Xiaowei; Dai, Zheng; Tang, Bing; Tang, Xiao-Feng

    2014-05-01

    Pyrolysin is an extracellular subtilase produced by the marine hyperthermophilic archaeon Pyrococcus furiosus. This enzyme functions at high temperatures in seawater, but little is known about the effects of metal ions on the properties of pyrolysin. Here, we report that the supplementation of Na(+), Ca(2+), or Mg(2+) salts at concentrations similar to those in seawater destabilizes recombinant pyrolysin but leads to an increase in enzyme activity. The destabilizing effect of metal ions on pyrolysin appears to be related to the disturbance of surface electrostatic interactions of the enzyme. In addition, mutational analysis of two predicted high-affinity Ca(2+)-binding sites (Ca1 and Ca2) revealed that the binding of Ca(2+) is important for the stabilization of this enzyme. Interestingly, Asn substitutions at residues Asp818 and Asp820 of the Ca2 site, which is located in the C-terminal extension of pyrolysin, resulted in improvements in both enzyme thermostability and activity without affecting Ca(2+)-binding affinity. These effects were most likely due to the elimination of unfavorable electrostatic repulsion at the Ca2 site. Together, these results suggest that metal ions play important roles in modulating the stability and activity of pyrolysin.

  7. Effects of Metal Ions on Stability and Activity of Hyperthermophilic Pyrolysin and Further Stabilization of This Enzyme by Modification of a Ca2+-Binding Site

    Science.gov (United States)

    Zeng, Jing; Gao, Xiaowei; Dai, Zheng; Tang, Bing

    2014-01-01

    Pyrolysin is an extracellular subtilase produced by the marine hyperthermophilic archaeon Pyrococcus furiosus. This enzyme functions at high temperatures in seawater, but little is known about the effects of metal ions on the properties of pyrolysin. Here, we report that the supplementation of Na+, Ca2+, or Mg2+ salts at concentrations similar to those in seawater destabilizes recombinant pyrolysin but leads to an increase in enzyme activity. The destabilizing effect of metal ions on pyrolysin appears to be related to the disturbance of surface electrostatic interactions of the enzyme. In addition, mutational analysis of two predicted high-affinity Ca2+-binding sites (Ca1 and Ca2) revealed that the binding of Ca2+ is important for the stabilization of this enzyme. Interestingly, Asn substitutions at residues Asp818 and Asp820 of the Ca2 site, which is located in the C-terminal extension of pyrolysin, resulted in improvements in both enzyme thermostability and activity without affecting Ca2+-binding affinity. These effects were most likely due to the elimination of unfavorable electrostatic repulsion at the Ca2 site. Together, these results suggest that metal ions play important roles in modulating the stability and activity of pyrolysin. PMID:24561589

  8. Role of AP-endonuclease (Ape1) active site residues in stabilization of the reactant enzyme-DNA complex.

    Science.gov (United States)

    Batebi, Hossein; Dragelj, Jovan; Imhof, Petra

    2018-04-01

    Apurinic/apyrimidinic endonuclease 1 (Ape1) is an important metal-dependent enzyme in the base excision repair mechanism, responsible for the backbone cleavage of abasic DNA through a phosphate hydrolysis reaction. Molecular dynamics simulations of Ape1 complexed to its substrate DNA performed for models containing 1 or 2 Mg 2+ -ions as cofactor located at different positions show a complex with 1 metal ion bound on the leaving group site of the scissile phosphate to be the most likely reaction-competent conformation. Active-site residue His309 is found to be protonated based on pKa calculations and the higher conformational stability of the Ape1-DNA substrate complex compared to scenarios with neutral His309. Simulations of the D210N mutant further support the prevalence of protonated His309 and strongly suggest Asp210 as the general base for proton acceptance by a nucleophilic water molecule. © 2018 Wiley Periodicals, Inc.

  9. Atomic scale determination of enzyme flexibility and active site stability through static modes: case of dihydrofolate reductase.

    Science.gov (United States)

    Brut, Marie; Estève, Alain; Landa, Georges; Renvez, Guillaume; Djafari Rouhani, Mehdi; Vaisset, Marc

    2011-02-24

    A Static Mode approach is used to screen the biomechanical properties of DHFR. In this approach, a specific external stimulus may be designed at the atomic scale granularity to arrive at a proper molecular mechanism. In this frame, we address the issues related to the overall molecular flexibility versus loop motions and versus enzymatic activity. We show that backbone motions are particularly important to ensure DHFR domain communication and notably highlight the role of a α-helix in Met20 loop motion. We also investigate the active site flexibility in different bound states. Whereas in the occluded conformation the Met20 loop is highly flexible, in the closed conformation backbone motions are no longer significant, the Met20 loop is rigidified by new intra- and intermolecular weak bonds, which stabilizes the complex and promotes the hydride transfer. Finally, while various simulations, including I14 V and I14A mutations, confirm that Ile14 is a key residue in catalytic activity, we isolate and characterize at the atomic scale how a specific intraresidue chemical group makes it possible to assist ligand positioning, to direct the nicotinamide ring toward the folate ring.

  10. Subunit CydX of Escherichia coli cytochrome bd ubiquinol oxidase is essential for assembly and stability of the di-heme active site.

    Science.gov (United States)

    Hoeser, Jo; Hong, Sangjin; Gehmann, Gerfried; Gennis, Robert B; Friedrich, Thorsten

    2014-05-02

    Cytochrome bd ubiquinol oxidase uses the electron transport from ubiquinol to oxygen to establish a proton gradient across the membrane. The enzyme complex consists of subunits CydA and B and contains two b- and one d-type hemes as cofactors. Recently, it was proposed that a third subunit named CydX is essential for the function of the complex. Here, we show that CydX is indeed a subunit of purified Escherichia coli cytochrome bd oxidase and that the small protein is needed either for the assembly or the stability of the active site di-heme center and, thus, is essential for oxidase activity. Copyright © 2014 Federation of European Biochemical Societies. All rights reserved.

  11. Stabilization of cytochrome b5 by a conserved tyrosine in the secondary sphere of heme active site: A spectroscopic and computational study

    Science.gov (United States)

    Hu, Shan; He, Bo; Wang, Xiao-Juan; Gao, Shu-Qin; Wen, Ge-Bo; Lin, Ying-Wu

    2017-03-01

    Heme proteins perform a large array of biological functions, with the heme group bound non-covalently or covalently. To probe the stabilization role of conserved tyrosine residue in the secondary sphere of heme site in heme proteins, we herein used cytochrome b5 (Cyt b5) as a model protein, and mutated Tyr30 to Phe or His by removal of Tyr30 associated H-bond network and hydrophobic interaction. We performed thermal-induced unfolding studies for the two mutants, Y30F Cyt b5 and Y30H Cyt b5, as monitored by both UV-Vis and CD spectroscopy, as well as heme transfer studies from these proteins to apo-myoglobin, with wild-type Cyt b5 under the same conditions for comparison. The reduced stability of both mutants indicates that both the H-bonding and hydrophobic interactions associated with Tyr30 contribute to the protein stability. Moreover, we performed molecular modeling studies, which revealed that the hydrophobic interaction in the local region of Y30F Cyt b5 was well-remained, whereas Y30H Cyt b5 formed an H-bond network. These observations suggest that the conserved Tyr30 in Cyt b5 is not replaceable due to the presence of both the H-bond network and hydrophobic interaction in the secondary sphere of the heme active site. As demonstrated here for Cyt b5, it may be of practical importance for design of artificial heme proteins by engineering a Tyr in the secondary sphere with improved properties and functions.

  12. Electrostatic stabilization and general base catalysis in the active site of the human protein disulfide isomerase a domain monitored by hydrogen exchange.

    Science.gov (United States)

    Hernández, Griselda; Anderson, Janet S; LeMaster, David M

    2008-03-25

    The nucleophilic Cys36 thiol of the human protein disulfide isomerase a domain is positioned over the N terminus of the alpha(2) helix. Amides in the active site exhibit diffusion-limited, hydroxide-catalyzed exchange, indicating that the local positive electrostatic potential decreases the pK value for peptide anion formation by at least 2 units so as to equal or exceed the acidity of water. In stark contrast to the pH dependence of exchange for simple peptides, the His38 amide in the reduced enzyme exhibits a maximum rate of exchange at pH 5 due to efficient general base catalysis by the neutral imidazole of its own side chain and suppression of its exchange by the ionization of the Cys36 thiol. Ionization of this thiol and deprotonation of the His38 side chain suppress the Cys39 amide hydroxide-catalyzed exchange by a million-fold. The electrostatic potential within the active site monitored by these exchange experiments provides a means of stabilizing the two distinct transition states that lead to substrate reduction and oxidation. Molecular modeling offers a role for the conserved Arg103 in coordinating the oxidative transition-state complex, thus providing further support for mechanisms of disulfide isomerization that utilize enzymatic catalysis at each step of the overall reaction.

  13. Effects of Metal Ions on Stability and Activity of Hyperthermophilic Pyrolysin and Further Stabilization of This Enzyme by Modification of a Ca2+-Binding Site

    OpenAIRE

    Zeng, Jing; Gao, Xiaowei; Dai, Zheng; Tang, Bing; Tang, Xiao-Feng

    2014-01-01

    Pyrolysin is an extracellular subtilase produced by the marine hyperthermophilic archaeon Pyrococcus furiosus. This enzyme functions at high temperatures in seawater, but little is known about the effects of metal ions on the properties of pyrolysin. Here, we report that the supplementation of Na+, Ca2+, or Mg2+ salts at concentrations similar to those in seawater destabilizes recombinant pyrolysin but leads to an increase in enzyme activity. The destabilizing effect of metal ions on pyrolysi...

  14. Single-Atom Mn Active Site in a Triol-Stabilized β-Anderson Manganohexamolybdate for Enhanced Catalytic Activity towards Adipic Acid Production

    Directory of Open Access Journals (Sweden)

    Jianhui Luo

    2018-03-01

    Full Text Available Adipic acid is an important raw chemical for the commercial production of polyamides and polyesters. The traditional industrial adipic acid production utilizes nitric acid to oxidize KA oil (mixtures of cyclohexanone and cyclohexanol, leading to the emission of N2O and thus causing ozone depletion, global warming, and acid rain. Herein, we reported an organically functionalized β-isomer of Anderson polyoxometalates (POMs nanocluster with single-atom Mn, β-{[H3NC(CH2O3]2MnMo6O18}− (1, as a highly active catalyst to selectively catalyze the oxidation of cyclohexanone, cyclohexanol, or KA oil with atom economy use of 30% H2O2 for the eco-friendly synthesis of adipic acid. The catalyst has been characterized by single crystal and powder XRD, XPS, ESI-MS, FT-IR, and NMR. A cyclohexanone (cyclohexanol conversion of >99.9% with an adipic acid selectivity of ~97.1% (~85.3% could be achieved over catalyst 1 with high turnover frequency of 2427.5 h−1 (2132.5 h−1. It has been demonstrated that the existence of Mn3+ atom active site in catalyst 1 and the special butterfly-shaped topology of POMs both play vital roles in the enhancement of catalytic activity.

  15. Understanding the role of histidine in the GHSxG acyltransferase active site motif: evidence for histidine stabilization of the malonyl-enzyme intermediate.

    Directory of Open Access Journals (Sweden)

    Sean Poust

    Full Text Available Acyltransferases determine which extender units are incorporated into polyketide and fatty acid products. The ping-pong acyltransferase mechanism utilizes a serine in a conserved GHSxG motif. However, the role of the conserved histidine in this motif is poorly understood. We observed that a histidine to alanine mutation (H640A in the GHSxG motif of the malonyl-CoA specific yersiniabactin acyltransferase results in an approximately seven-fold higher hydrolysis rate over the wildtype enzyme, while retaining transacylation activity. We propose two possibilities for the reduction in hydrolysis rate: either H640 structurally stabilizes the protein by hydrogen bonding with a conserved asparagine in the ferredoxin-like subdomain of the protein, or a water-mediated hydrogen bond between H640 and the malonyl moiety stabilizes the malonyl-O-AT ester intermediate.

  16. DNA damage, acetylcholinesterase activity and lysosomal stability in native and transplanted mussels (Mytilus edulis) in areas close to coastal chemical dumping sites in Denmark

    DEFF Research Database (Denmark)

    Rank, Jette; Lehtonen, Kari K.; Strand, Jakob

    2007-01-01

    Biomarkers of genotoxicity (DNA damage, measured as tail moment in the Comet assay), neurotoxicity (acetylcholinesterase inhibition, AChE) and general stress (lysosomal membrane stability, LMS) were studied in native and transplanted blue mussels (Mytilus edulis) in coastal areas of western Denmark...... of chemical pollution complex, as seen especially in the variability in results on DNA damage, and also in regard to AChE activity. These investigations further stress the importance of understanding the effects of natural factors (salinity, temperature, water levels, rain and storm events) in correct...

  17. DOE site performance assessment activities

    International Nuclear Information System (INIS)

    1990-07-01

    Information on performance assessment capabilities and activities was collected from eight DOE sites. All eight sites either currently dispose of low-level radioactive waste (LLW) or plan to dispose of LLW in the near future. A survey questionnaire was developed and sent to key individuals involved in DOE Order 5820.2A performance assessment activities at each site. The sites surveyed included: Hanford Site (Hanford), Idaho National Engineering Laboratory (INEL), Los Alamos National Laboratory (LANL), Nevada Test Site (NTS), Oak Ridge National Laboratory (ORNL), Paducah Gaseous Diffusion Plant (Paducah), Portsmouth Gaseous Diffusion Plant (Portsmouth), and Savannah River Site (SRS). The questionnaire addressed all aspects of the performance assessment process; from waste source term to dose conversion factors. This report presents the information developed from the site questionnaire and provides a comparison of site-specific performance assessment approaches, data needs, and ongoing and planned activities. All sites are engaged in completing the radioactive waste disposal facility performance assessment required by DOE Order 5820.2A. Each site has achieved various degrees of progress and have identified a set of critical needs. Within several areas, however, the sites identified common needs and questions

  18. Soil stabilization mat for lunar launch/landing site

    Science.gov (United States)

    Acord, Amy L.; Cohenour, Mark W.; Ephraim, Daniel; Gochoel, Dennis; Roberts, Jefferson G.

    1990-01-01

    Facilities which are capable of handling frequent arrivals and departures of spaceships between Earth and a lunar colony are necessary. The facility must be able to provide these services with minimal interruption of operational activity within the colony. The major concerns associated with the space traffic are the dust and rock particles that will be kicked up by the rocket exhaust. As a result of the reduced gravitation of the Moon, these particles scatter over large horizontal distances. This flying debris will not only seriously interrupt the routine operations of the colony, but could cause damage to the equipment and facilities surrounding the launch site. An approach to overcome this problem is presented. A proposed design for a lunar take-off/landing mat is presented. This proposal goes beyond dealing with the usual problems of heat and load resistances associated with take-off and landing, by solving the problem of soil stabilization at the site. Through adequate stabilization, the problem of flying debris is eliminated.

  19. Positively selected sites in cetacean myoglobins contribute to protein stability.

    Directory of Open Access Journals (Sweden)

    Pouria Dasmeh

    Full Text Available Since divergence ∼50 Ma ago from their terrestrial ancestors, cetaceans underwent a series of adaptations such as a ∼10-20 fold increase in myoglobin (Mb concentration in skeletal muscle, critical for increasing oxygen storage capacity and prolonging dive time. Whereas the O2-binding affinity of Mbs is not significantly different among mammals (with typical oxygenation constants of ∼0.8-1.2 µM(-1, folding stabilities of cetacean Mbs are ∼2-4 kcal/mol higher than for terrestrial Mbs. Using ancestral sequence reconstruction, maximum likelihood and bayesian tests to describe the evolution of cetacean Mbs, and experimentally calibrated computation of stability effects of mutations, we observe accelerated evolution in cetaceans and identify seven positively selected sites in Mb. Overall, these sites contribute to Mb stabilization with a conditional probability of 0.8. We observe a correlation between Mb folding stability and protein abundance, suggesting that a selection pressure for stability acts proportionally to higher expression. We also identify a major divergence event leading to the common ancestor of whales, during which major stabilization occurred. Most of the positively selected sites that occur later act against other destabilizing mutations to maintain stability across the clade, except for the shallow divers, where late stability relaxation occurs, probably due to the shorter aerobic dive limits of these species. The three main positively selected sites 66, 5, and 35 undergo changes that favor hydrophobic folding, structural integrity, and intra-helical hydrogen bonds.

  20. Probabilistic approaches for geotechnical site characterization and slope stability analysis

    CERN Document Server

    Cao, Zijun; Li, Dianqing

    2017-01-01

    This is the first book to revisit geotechnical site characterization from a probabilistic point of view and provide rational tools to probabilistically characterize geotechnical properties and underground stratigraphy using limited information obtained from a specific site. This book not only provides new probabilistic approaches for geotechnical site characterization and slope stability analysis, but also tackles the difficulties in practical implementation of these approaches. In addition, this book also develops efficient Monte Carlo simulation approaches for slope stability analysis and implements these approaches in a commonly available spreadsheet environment. These approaches and the software package are readily available to geotechnical practitioners and alleviate them from reliability computational algorithms. The readers will find useful information for a non-specialist to determine project-specific statistics of geotechnical properties and to perform probabilistic analysis of slope stability.

  1. Soil Stabilization Methods with Potential for Application at the Nevada National Security Site: A Literature Review

    Energy Technology Data Exchange (ETDEWEB)

    Shillito, Rose [DRI; Fenstermaker, Lynn [DRI

    2014-01-01

    Nuclear testing at the Nevada National Security Site (NNSS) has resulted in large areas of surficial radionuclide-contaminated soils. Much of the radionuclide contamination is found at or near the soil surface, and due to the dry climate setting, and the long half-life of radioactive isotopes, soil erosion poses a long-term health risk at the NNSS. The objective of this literature review is to present a survey of current stabilization methods used for minimizing soil erosion, both by water and wind. The review focuses on in situ uses of fundamental chemical and physical mechanisms for soil stabilization. A basic overview of the physical and chemical properties of soil is also presented to provide a basis for assessing stabilization methods. Some criteria for stabilization evaluation are identified based on previous studies at the NNSS. Although no specific recommendations are presented as no stabilization method, alone or in combination, will be appropriate in all circumstances, discussions of past and current stabilization procedures and specific soil tests that may aid in current or future soil stabilization activities at the NNSS are presented. However, not all Soils Corrective Action Sites (CASs) or Corrective Action Units (CAUs) will require stabilization of surficial radionuclide-contaminated soils. Each Soils CAS or CAU should be evaluated for site-specific conditions to determine if soil stabilization is necessary or practical for a given specific site closure alternative. If stabilization is necessary, then a determination will be made as to which stabilization technique is the most appropriate for that specific site.

  2. Stability-class determination: a comparison for one site

    International Nuclear Information System (INIS)

    Bowen, B.M.; Dewart, J.M.; Chen, A.I.

    1983-01-01

    The Pasquill method of determining stability class at a site with irregular terrain with other commonly used methods: vertical temperature difference (#betta#T); Richardson number (Ri) and Bulk Richardson number (Ri/sub B/); and horizontal standard deviation of wind and vertical standard deviation of wind. Also, the indirect methods of measuring turbulence, such as the Pasquill method, are compared to direct measures of turbulence. The various methods for determining stability class are analyzed and compared with the Pasquill classification scheme at 2 sites with irregular terrain. The Pasquill categories were estimated objectively and compared with other stability indicators for 15-minute periods over a year. The results show that near-surface #betta#T distinguishes the neutral category very well. However, it does not differentiate the specific stable and unstable categories very well. Both the Ri and Ri/sub B/, indicators of both thermal and mechanical turbulence, correlate very well with and distinguish the different stability categories. Due to the irregular terrain, the various methods of determining stability may be even better indicators of turbulence and diffusion if the wind direction were taken into account. It is suggested that further study investigate the methods by wind direction

  3. Active site CP-loop dynamics modulate substrate binding, catalysis, oligomerization, stability, over-oxidation and recycling of 2-Cys Peroxiredoxins.

    Science.gov (United States)

    Kamariah, Neelagandan; Eisenhaber, Birgit; Eisenhaber, Frank; Grüber, Gerhard

    2018-04-01

    Peroxiredoxins (Prxs) catalyse the rapid reduction of hydrogen peroxide, organic hydroperoxide and peroxynitrite, using a fully conserved peroxidatic cysteine (C P ) located in a conserved sequence Pxxx(T/S)xxC P motif known as C P -loop. In addition, Prxs are involved in cellular signaling pathways and regulate several redox-dependent process related disease. The effective catalysis of Prxs is associated with alterations in the C P -loop between reduced, Fully Folded (FF), and oxidized, Locally Unfolded (LU) conformations, which are linked to dramatic changes in the oligomeric structure. Despite many studies, little is known about the precise structural and dynamic roles of the C P -loop on Prxs functions. Herein, the comprehensive biochemical and biophysical studies on Escherichia coli alkyl hydroperoxide reductase subunit C (EcAhpC) and the C P -loop mutants, EcAhpC-F45A and EcAhpC-F45P reveal that the reduced form of the C P -loop adopts conformational dynamics, which is essential for effective peroxide reduction. Furthermore, the point mutants alter the structure and dynamics of the reduced form of the C P -loop and, thereby, affect substrate binding, catalysis, oligomerization, stability and overoxidiation. In the oxidized form, due to restricted C P -loop dynamics, the EcAhpC-F45P mutant favours a decamer formation, which enhances the effective recycling by physiological reductases compared to wild-type EcAhpC. In addition, the study reveals that residue F45 increases the specificity of Prxs-reductase interactions. Based on these studies, we propose an evolution of the C P -loop with confined sequence conservation within Prxs subfamilies that might optimize the functional adaptation of Prxs into various physiological roles. Copyright © 2018 Elsevier Inc. All rights reserved.

  4. Evolution of an Antibiotic Resistance Enzyme Constrained by Stability and Activity Trade-offs

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Xiaojun; Minasov, George; Shoichet, Brian K. (NWU)

    2010-03-08

    Pressured by antibiotic use, resistance enzymes have been evolving new activities. Does such evolution have a cost? To investigate this question at the molecular level, clinically isolated mutants of the {beta}-lactamase TEM-1 were studied. When purified, mutant enzymes had increased activity against cephalosporin antibiotics but lost both thermodynamic stability and kinetic activity against their ancestral targets, penicillins. The X-ray crystallographic structures of three mutant enzymes were determined. These structures suggest that activity gain and stability loss is related to an enlarged active site cavity in the mutant enzymes. In several clinically isolated mutant enzymes, a secondary substitution is observed far from the active site (Met182 {yields} Thr). This substitution had little effect on enzyme activity but restored stability lost by substitutions near the active site. This regained stability conferred an advantage in vivo. This pattern of stability loss and restoration may be common in the evolution of new enzyme activity.

  5. Surgical site infections following instrumented stabilization of the spine

    Directory of Open Access Journals (Sweden)

    Dapunt U

    2017-09-01

    Full Text Available Ulrike Dapunt,1 Caroline Bürkle,1 Frank Günther,2 Wojciech Pepke,1 Stefan Hemmer,1 Michael Akbar1 1Clinic for Orthopedics and Trauma Surgery, Center for Orthopedics, Trauma Surgery and Spinal Cord Injury, Heidelberg University Hospital, 2Department for Infectious Diseases, Medical Microbiology and Hygiene, Heidelberg University, Heidelberg, Germany Background: Implant-associated infections are still a feared complication in the field of orthopedics. Bacteria attach to the implant surface and form so-called biofilm colonies that are often difficult to diagnose and treat. Since the majority of studies focus on prosthetic joint infections (PJIs of the hip and knee, current treatment options (eg, antibiotic prophylaxis of implant-associated infections have mostly been adapted according to these results. Objective: The aim of this study was to evaluate patients with surgical site infections following instrumented stabilization of the spine with regard to detected bacteria species and the course of the disease. Patients and methods: We performed a retrospective single-center analysis of implant-associated infections of the spine from 2010 to 2014. A total of 138 patients were included in the study. The following parameters were evaluated: C-reactive protein serum concentration, microbiological evaluation of tissue samples, the time course of the disease, indication for instrumented stabilization of the spine, localization of the infection, and the number of revision surgeries required until cessation of symptoms. Results: Coagulase-negative Staphylococcus spp. were most commonly detected (n=69, 50%, followed by fecal bacteria (n=46, 33.3%. In 23.2% of cases, no bacteria were detected despite clinical suspicion of an infection. Most patients suffered from degenerative spine disorders (44.9%, followed by spinal fractures (23.9%, non-degenerative scoliosis (20.3%, and spinal tumors (10.1%. Surgical site infections occurred predominantly within 3

  6. Vehicle lateral dynamics stabilization using active suspension

    Directory of Open Access Journals (Sweden)

    Drobný V.

    2008-12-01

    Full Text Available The paper deals with the investigation of active nonlinear suspension control in order to stabilize the lateral vehicle motion in similar way as systems like ESP do. The lateral stabilization of vehicle based on braking forces can be alternatively provided by the different setting of suspension forces. The basis of this control is the nonlinear property of the tyres. The vehicle has at least four wheels and it gives one or more redundant vertical forces that can be used for the different distribution of vertical suspension forces in such a way that resulting lateral and/or longitudinal forces create the required correction moment for lateral dynamic vehicle stabilization.

  7. Does implant design affect primary stability in extraction sites?

    Science.gov (United States)

    Karl, Matthias; Irastorza-Landa, Ainara

    2017-01-01

    Immediate implant placement and restoration following tooth extraction is desirable for shortening treatment times and maintaining oral structures. With a variety of bone-level implants available on the market, the goal of this in-vitro study was to compare different implant designs. Using a polyurethane foam sandwich model with an intermediate cortical layer, a standardized extraction socket model was created. The following implant systems were assessed: OsseoSpeed EV (Astra), Straumann Bone Level Tapered (BLT), and Nobel Active (NA). Implant stability assessment included implant insertion torque (IT) and implant stability quotient (ISQ). The three implant systems were compared in a statistical analysis based on the two sample tests with the level of significance set at α = .05 and Bonferroni correction for multiple comparisons. The relationship between IT and ISQ was assessed using the Pearson correlation coefficient. IT values were highest for NA implants, with a mean of 36.52 Ncm, which was significantly greater than in BLT (P extraction model allowed for consistent measurements of implant stability parameters at a clinically relevant level. Implant design seems to play a relevant role for achieving primary stability in challenging situations. Next evaluation steps should involve testing under dynamic loading conditions.

  8. Active Risk Management and Banking Stability

    NARCIS (Netherlands)

    Silva Buston, C.F.

    2013-01-01

    Abstract: This paper analyzes the net impact of two opposing effects of active risk management at banks on their stability: higher risk-taking incentives and better isolation of credit supply from varying economic conditions. We present a model where banks actively manage their portfolio risk by

  9. Towards Stabilizing Parametric Active Contours

    DEFF Research Database (Denmark)

    Liu, Jinchao; Fan, Zhun; Olsen, Søren Ingvor

    2014-01-01

    to a parametrization that is proportional to the natural parametrization which implies that the control points of the contour are uniformly distributed. We theoretically prove that this tangential diffusion term is bounded and therefore numerically stable. Several experiments were conducted and verified......Numerical instability often occurs in evolving of parametric active contours. This is mainly due to the undesired change of parametrization during evolution. In this paper, we propose a new tangential diffusion term to compensate this undesired change. As a result, the parametrization will converge...

  10. Synergistic Effects of Copper Sites on Apparent Stability of Multicopper Oxidase, Fet3p

    Directory of Open Access Journals (Sweden)

    Erik Sedlák

    2018-01-01

    Full Text Available Saccharomyces cerevisiae Fet3p is a multicopper oxidase that contains three cupredoxin-like domains and four copper ions located in three distinct metal sites (T1 in domain 3; T2 and the binuclear T3 at the interface between domains 1 and 3. To probe the role of the copper sites in Fet3p thermodynamic stability, we performed urea-induced unfolding experiments with holo-, apo- and three partially-metallated (T1, T2 and T1/T2 sites depleted of copper forms of Fet3p. Using a combination of spectroscopic probes (circular dichroism, fluorescence intensity and maximum, 8-anilinonaphthalene-1-sulfonic acid (ANS emission, oxidase activity and blue color, we reveal that all forms of Fet3p unfold in a four-state reaction with two partially-folded intermediates. Using phase diagrams, it emerged that Fet3p with all copper sites filled had a significantly higher stability as compared to the combined contributions of the individual copper sites. Hence, there is long-range inter-domain communication between distal copper sites that contribute to overall Fet3p stability.

  11. On-site and off-site activities

    International Nuclear Information System (INIS)

    Martin, H.D.

    1986-01-01

    Design principles for NPP training programs. Effects of NPP contracts. Effects of domestic industrial activities. The role of international bodies. Requirements for on-site training. Training abroad, technical, financial and social aspects. Training center on-site, an evaluation. (orig.)

  12. Remedial action plan and site design for stabilization of the inactive uranium mill tailings site at Tuba City, Arizona

    International Nuclear Information System (INIS)

    1989-08-01

    This Remedial Action Plan (RAP) has been developed to serve a threefold purpose. It presents the series of activities which are proposed by the US Department of Energy (DOE) to accomplish long-term stabilization and control of radioactive materials at the inactive uranium processing site near Tuba City, Arizona. It provides a characterization of the present conditions of the site. It also serves to document the concurrence of the Navajo Nation, the Hopi Tribe, US Bureau of Indian Affairs (BIA), and the US Nuclear Regulatory Commission (NRC) in the remedial action. This agreement, upon execution by DOE, the Navajo Nation, and the Hopi Tribe, and concurrence by NRC, becomes Appendix B of the Cooperative Agreement. Following the introduction, contents are as follows: Section 2.0 presents the EPA standards, including a discussion of their objectives. Section 3.0 summarizes the present site characteristics and provides a definition of site-specific problems. Section 4.0 is the site design for the proposed action. Section 5.0 summarizes the plan for ensuring environmental, health, and safety protection for the surrounding community and the on-site workers. Section 6.0 presents a detailed listing of the responsibilities of the project participants. Section 7.0 describes the features of the long-term surveillance and maintenance plan. Section 8.0 presents the quality assurance aspects of the project. Section 9.0 documents the ongoing activities to keep the public informed and participating in the project

  13. Remedial Action Plan and site conceptual design for stabilization of the inactive uranium mill tailings site at Spook, Wyoming

    Energy Technology Data Exchange (ETDEWEB)

    Matthews, M L [USDOE Albuquerque Operations Office, NM (United States). Uranium Mill Tailings Remedial Action Project Office; Sullivan, M [Wyoming State Government, Cheyenne, WY (United States)

    1990-04-01

    This Remedial Action Plan (RAP) has been developed to serve a threefold purpose. It presents the series of activities which are proposed by the US Department of Energy (DOE) to accomplish long-term stabilization and control of radioactive materials at an inactive uranium processing site northeast of Casper, Wyoming, and referred to as the Spook site. It provides a characterization of the present conditions at the site and also serves to document the concurrence of the State of Wyoming and the US Nuclear Regulatory Commission (NRC) in the remedial action. This agreement, upon execution by the DOE and the State of Wyoming, and concurrence by the NRC, becomes Appendix B of the Cooperative Agreement.

  14. Remedial Action Plan and site conceptual design for stabilization of the inactive uranium mill tailings site at Spook, Wyoming

    International Nuclear Information System (INIS)

    Matthews, M.L.

    1990-04-01

    This Remedial Action Plan (RAP) has been developed to serve a threefold purpose. It presents the series of activities which are proposed by the US Department of Energy (DOE) to accomplish long-term stabilization and control of radioactive materials at an inactive uranium processing site northeast of Casper, Wyoming, and referred to as the Spook site. It provides a characterization of the present conditions at the site and also serves to document the concurrence of the State of Wyoming and the US Nuclear Regulatory Commission (NRC) in the remedial action. This agreement, upon execution by the DOE and the State of Wyoming, and concurrence by the NRC, becomes Appendix B of the Cooperative Agreement

  15. Analysis of cavern stability at the Bryan Mound SPR site.

    Energy Technology Data Exchange (ETDEWEB)

    Ehgartner, Brian L.; Sobolik, Steven Ronald

    2009-04-01

    This report presents computational analyses that simulate the structural response of caverns at the Strategic Petroleum Reserve Bryan Mound site. The cavern field comprises 20 caverns. Five caverns (1, 2, 4, and 5; 3 was later plugged and abandoned) were acquired from industry and have unusual shapes and a history dating back to 1946. The other 16 caverns (101-116) were leached according to SPR standards in the mid-1980s and have tall cylindrical shapes. The history of the caverns and their shapes are simulated in a 3-D geomechanics model of the site that predicts deformations, strains, and stresses. Future leaching scenarios due to oil drawdowns using fresh water are also simulated by increasing the volume of the caverns. Cavern pressures are varied in the model to capture operational practices in the field. The results of the finite element model are interpreted to provide information on the current and future status of subsidence, well integrity, and cavern stability. The most significant result in this report is relevant to caverns 1, 2, and 5. The caverns have non-cylindrical shapes and have potential regions where the surrounding salt may be damaged during workover procedures. During a workover the normal cavern operating pressure is lowered to service a well. At this point the wellhead pressures are atmospheric. When the workover is complete, the cavern is repressurized. The resulting elastic stresses are sufficient to cause tension and large deviatoric stresses at several locations. With time, these stresses relax to a compressive state due to salt creep. However, the potential for salt damage and fracturing exists. The analyses predict tensile stresses at locations with sharp-edges in the wall geometry, or in the case of cavern 5, in the neck region between the upper and lower lobes of the cavern. The effects do not appear to be large-scale, however, so the only major impact is the potential for stress-induced salt falls in cavern 5, potentially leading to

  16. Direct epoxidation of propylene over stabilized Cu(+) surface sites on titanium-modified Cu2O.

    Science.gov (United States)

    Yang, Xiaofang; Kattel, Shyam; Xiong, Ke; Mudiyanselage, Kumudu; Rykov, Sergei; Senanayake, Sanjaya D; Rodriguez, José A; Liu, Ping; Stacchiola, Dario J; Chen, Jingguang G

    2015-10-05

    Direct propylene epoxidation by O2 is a challenging reaction because of the strong tendency for complete combustion. Results from the current study demonstrate that by generating highly dispersed and stabilized Cu(+) active sites in a TiCuOx mixed oxide the epoxidation selectivity can be tuned. The TiCuOx surface anchors the key surface intermediate, an oxametallacycle, leading to higher selectivity for epoxidation of propylene. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  17. Analysis of cavern stability at the West Hackberry SPR site.

    Energy Technology Data Exchange (ETDEWEB)

    Ehgartner, Brian L.; Sobolik, Steven Ronald

    2009-05-01

    This report presents computational analyses that simulate the structural response of caverns at the Strategic Petroleum Reserve (SPR) West Hackberry site. The cavern field comprises 22 caverns. Five caverns (6, 7, 8, 9, 11) were acquired from industry and have unusual shapes and a history dating back to 1946. The other 17 caverns (101-117) were leached according to SPR standards in the mid-1980s and have tall cylindrical shapes. The history of the caverns and their shapes are simulated in a three-dimensional geomechanics model of the site that predicts deformations, strains, and stresses. Future leaching scenarios corresponding to oil drawdowns using fresh water are also simulated by increasing the volume of the caverns. Cavern pressures are varied in the model to capture operational practices in the field. The results of the finite element model are interpreted to provide information on the current and future status of subsidence, well integrity, and cavern stability. The most significant results in this report are relevant to Cavern 6. The cavern is shaped like a bowl with a large ceiling span and is in close proximity to Cavern 9. The analyses predict tensile stresses at the edge of the ceiling during repressuization of Cavern 6 following workover conditions. During a workover the cavern is at low pressure to service a well. The wellhead pressures are atmospheric. When the workover is complete, the cavern is repressurized. The resulting elastic stresses are sufficient to cause tension around the edge of the large ceiling span. With time, these stresses relax to a compressive state because of salt creep. However, the potential for salt fracture and propagation exists, particularly towards Cavern 9. With only 200 ft of salt between the caverns, the operational consequences must be examined if the two caverns become connected. A critical time may be during a workover of Cavern 9 in part because of the operational vulnerabilities, but also because dilatant damage is

  18. IMPACT OF PSYCHOLOGICAL STABILITY ON MANAGERS’ ACTIVITIES

    Directory of Open Access Journals (Sweden)

    Tsvetelina Мihailova

    2016-10-01

    Full Text Available The latest research performed in European countries shows that the psychosocial risks and the job related stress will become more and more important in the years to come due to their increasing spread. These trends will have even greater influence on healthcare managers' activities due to the specific nature of their jobs, which, in turn, increases the needs of efficient leadership. The purpose of the questionnaire held is to study the impact of healthcare managers’ psychological stability on the activities they perform in the course of their jobs. The analysis made shows that an individual’s performance depends on their motivation, abilities and organizational conditions and skills. What is also found out is that people with different types of behavioral control work in healthcare operative management. People with different types of psychological stability will be needed for the different management levels.

  19. Multi-site breathers in Klein–Gordon lattices: stability, resonances and bifurcations

    International Nuclear Information System (INIS)

    Pelinovsky, Dmitry; Sakovich, Anton

    2012-01-01

    We prove a general criterion of spectral stability of multi-site breathers in the discrete Klein–Gordon equation with a small coupling constant. In the anti-continuum limit, multi-site breathers represent excited oscillations at different sites of the lattice separated by a number of ‘holes’ (sites at rest). The criterion describes how the stability or instability of a multi-site breather depends on the phase difference and distance between the excited oscillators. Previously, only multi-site breathers with adjacent excited sites were considered within the first-order perturbation theory. We show that the stability of multi-site breathers with one-site holes changes for large-amplitude oscillations in soft nonlinear potentials. We also discover and study a symmetry-breaking (pitchfork) bifurcation of one-site and multi-site breathers in soft quartic potentials near the points of 1 : 3 resonance. (paper)

  20. Efficient oxygen electrocatalysis on special active sites

    DEFF Research Database (Denmark)

    Halck, Niels Bendtsen

    Oxygen electrocatalysis will be pivotal in future independent of fossil fuels. Renewable energy production will rely heavily on oxygen electrocatalysis as a method for storing energy from intermittent energy sources such as the wind and sun in the form of chemical bonds and to release the energy...... throughout this thesis to understand these local structure effects and their influence on surface reactions. The concept of these special active sites is used to explain how oxygen evolution reaction (OER) catalysts can have activities beyond the limits of what was previously thought possible. The concept...... functional theory calculation provides an insight into the how the activity is increased at these special active sites and proposes a modified reaction mechanism for the oxygen evolution reaction on these sites. Another type of special active site can explain the production of hydrogen peroxide on nickel...

  1. Remedial Action Plan and site design for stabilization of the inactive uranium mill tailings site at Falls City, Texas

    International Nuclear Information System (INIS)

    Chernoff, A.R.; Lacker, D.K.

    1992-09-01

    The uranium processing site near Falls City, Texas, was one of 24 inactive uranium mill sites designated to be remediated by the US Department of Energy (DOE) under Title I of the Uranium Mill Tailings Radiation Control Act of 1978 (UMTRCA). The UMTRCA requires that the US Nuclear Regulatory Commission (NRC) concur with the DOE's remedial action plan (RAP) and certify that the remedial action conducted at the site complies with the standards promulgated by the US Environmental Protection Agency (EPA). The RAP, which includes this summary remedial action selection report (RAS), serves a two-fold purpose. First, it describes the activities proposed by the DOE to accomplish long-term stabilization and control of the residual radioactive materials at the inactive uranium processing site near Falls City, Texas. Second, this document and the remainder of the RAP, upon concurrence and execution by the DOE, the State of Texas, and the NRC, becomes Appendix B of the Cooperative Agreement between the DOE and the State of Texas

  2. Remedial action plan and site design for stabilization of the inactive uranium processing site at Naturita, Colorado

    International Nuclear Information System (INIS)

    1993-08-01

    The uranium processing site near Naturita, Colorado, is one of 24 inactive uranium mill sites designated to be cleaned up by the US Department of Energy (DOE) under the Uranium Mill Tailings Radiation Control Act of 1978 (UMTRCA), Public Law 95-604. Part of the UMTRCA requires that the US Nuclear Regulatory Commission (NRC) concur with the DOE's remedial action plan (RAP) and certify that the remedial action conducted at the site complies with the standards promulgated by the US Environmental Protection Agency (EPA). Included in the RAP is this Remedial Action Selection Report (RAS), which serves two purposes. First, it describes the activities that are proposed by the DOE to accomplish remediation and long-term stabilization and control of the radioactive materials at the inactive uranium processing site near Naturita, Colorado. Second, this document and the rest of the RAP, upon concurrence and execution by the DOE, the state of Colorado, and the NRC, become Appendix B of the cooperative agreement between the DOE and the State of Colorado

  3. Remedial action and site design for stabilization of the inactive uranium mill tailings sites at Slick Rock, Colorado

    International Nuclear Information System (INIS)

    1993-07-01

    This report presents geologic considerations that are pertinent to the Remedial Action Plan for Slick Rock mill tailings. Topics covered include regional geology, site geology, geologic stability, and geologic suitability

  4. Chemical and Enzymatic Site Specific PEGylation of hGH: The Stability and in vivo Activity of PEG-N-Terminal-hGH and PEG-Gln141-hGH Conjugates.

    Science.gov (United States)

    Grigoletto, Antonella; Mero, Anna; Zanusso, Ilenia; Schiavon, Oddone; Pasut, Gianfranco

    2016-01-01

    The use of therapeutic proteins is often impaired by their short in vivo half-lives. PEGylation has been exploited to enhance protein stability and to prolong the pharmacokinetic. The biophysical characterization of two site-specific mono-PEGylated forms of human growth hormone (hGH)--chemically N-terminal PEGylated hGH (PEG-Nter-hGH) and enzymatically Gln141 PEGylated hGH (PEG-Gln141-hGH) via transglutaminase--is outlined here and their pharmacodynamics are compared. The thermal stability of PEG-Nter-hGH was increased with respect to that of hGH and PEG-Gln141-hGH. Pharmacodynamic studies in rats showed that a single injection of the conjugates had a better or comparable potency with respect to a daily hGH on a week schedule in terms of weight gain, femoral length, and tibial diaphysis width. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  5. Geomorphic stability field reconnaissance site visit, Canonsburg, Pennsylvania, December 1992. Final report

    International Nuclear Information System (INIS)

    1993-05-01

    To license the Canonsburg site, the US Nuclear Regulatory Commission (NRC) has required that geomorphic stability be demonstrated for the stream banks and slopes around the perimeter of the site for 200 years. Based on a study of the stream channel and slopes, it has been determined that due to recent human intervention, the required geomorphic stability cannot now be achieved without installation of erosion protection works and continued monitoring of the site. The Pittsburgh District Corps of Engineers has plans to channelize Chartiers Creek and install erosion protection rock within the next 5 or 6 years, if local government agencies raise the necessary matching funds. Much of the stream bank and slope adjacent to the ''fenced in'' western area of the site is anticipated to remain geomorphically stable for more than 20 years, but less than 200 years without human intervention. Therefore in much of this area, the Corps of Engineers will have adequate time to perform its work without jeopardizing the integrity of the controlled area. In contrast, two approximately 200-foot (ft) (60-meter [m]) long portions of the stream channel located north-northwest of the encapsulation area are subject to active stream erosion that threatens the integrity of the controlled area. These areas should be fixed by installation of erosion protection rock within the next 2 years

  6. Catalysis: Elusive active site in focus

    Science.gov (United States)

    Labinger, Jay A.

    2016-08-01

    The identification of the active site of an iron-containing catalyst raises hopes of designing practically useful catalysts for the room-temperature conversion of methane to methanol, a potential fuel for vehicles. See Letter p.317

  7. 10 CFR 61.62 - Funding for disposal site closure and stabilization.

    Science.gov (United States)

    2010-01-01

    ... 10 Energy 2 2010-01-01 2010-01-01 false Funding for disposal site closure and stabilization. 61.62 Section 61.62 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) LICENSING REQUIREMENTS FOR LAND DISPOSAL OF RADIOACTIVE WASTE Financial Assurances § 61.62 Funding for disposal site closure and stabilization. (a) The...

  8. 10 CFR 61.44 - Stability of the disposal site after closure.

    Science.gov (United States)

    2010-01-01

    ... 10 Energy 2 2010-01-01 2010-01-01 false Stability of the disposal site after closure. 61.44 Section 61.44 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) LICENSING REQUIREMENTS FOR LAND DISPOSAL OF RADIOACTIVE WASTE Performance Objectives § 61.44 Stability of the disposal site after closure. The disposal...

  9. Positively selected sites in cetacean myoglobins contribute to protein stability

    DEFF Research Database (Denmark)

    Dasmeh, Pouria; Serohijos, Adrian W R; Kepp, Kasper P

    2013-01-01

    Since divergence ∼50 Ma ago from their terrestrial ancestors, cetaceans underwent a series of adaptations such as a ∼10-20 fold increase in myoglobin (Mb) concentration in skeletal muscle, critical for increasing oxygen storage capacity and prolonging dive time. Whereas the O2-binding affinity...... between Mb folding stability and protein abundance, suggesting that a selection pressure for stability acts proportionally to higher expression. We also identify a major divergence event leading to the common ancestor of whales, during which major stabilization occurred. Most of the positively selected...

  10. Managing Siting Activities for Nuclear Power Plants

    International Nuclear Information System (INIS)

    2012-01-01

    One of the IAEA's statutory objectives is to ''seek to accelerate and enlarge the contribution of atomic energy to peace, health and prosperity throughout the world''. One way this objective is achieved is through the publication of a range of technical series. Two of these are the IAEA Nuclear Energy Series and the IAEA Safety Standards Series. According to Article III.A.6 of the IAEA Statute, the safety standards establish 'standards of safety for protection of health and minimization of danger to life and property.' The safety standards include the Safety Fundamentals, Safety Requirements and Safety Guides. These standards are written primarily in a regulatory style, and are binding on the IAEA for its own programmes. The principal users are the regulatory bodies in Member States and other national authorities. The IAEA Nuclear Energy Series comprises reports designed to encourage and assist R and D on, and application of, nuclear energy for peaceful uses. This includes practical examples to be used by owners and operators of utilities in Member States, implementing organizations, academia, and government officials, among others. This information is presented in guides, reports on technology status and advances, and best practices for peaceful uses of nuclear energy based on inputs from international experts. The IAEA Nuclear Energy Series complements the IAEA Safety Standards Series. The introduction of nuclear power brings new challenges to States - one of them being the selection of appropriates sites. It is a project that needs to begin early, be well managed, and deploy good communications with all stakeholders; including regulators. This is important, not just for those States introducing nuclear power for the first time, but for any State looking to build a new nuclear power plant. The purpose of the siting activities goes beyond choosing a suitable site and acquiring a licence. A large part of the project is about producing and maintaining a validated

  11. Effect of soil erosion on the long-term stability of FUSRAP near-surface waste-burial sites

    Energy Technology Data Exchange (ETDEWEB)

    Knight, M.J.

    1983-04-01

    Decontamination of FUSRAP sites could result in the generation of large volumes (in excess of 400,000 m/sup 3/) of low-activity radioactive wastes (primarily contaminated soil and building materials) requiring subsequent disposal. It is likely that near-surface burial will be seriously considered as an option for disposal of these materials. A number of factors - including soil erosion - could adversely affect the long-term stability of a near-surface waste-burial site. The majority of FUSRAP sites are located in the humid eastern United States, where the principal cause of erosion is the action of water. This report examines the effect of soil erosion by water on burial-site stability based on analysis of four hypothetical near-surface burial sites. The Universal Soil Loss Equation was employed to estimate average annual soil loss from burial sites and the 1000-year effects of soil loss on the soil barrier (burial trench cap) placed over low-activity wastes. Results suggest that the land use of the burial site and the slope gradient of the burial trench cap significantly affect the rate of soil erosion. The development of measures limiting the potential land use of a burial site (e.g., mixing large rocks into the burial trench cap) may be required to preserve the integrity of a burial trench for long periods of time.

  12. Effect of soil erosion on the long-term stability of FUSRAP near-surface waste-burial sites

    International Nuclear Information System (INIS)

    Knight, M.J.

    1983-04-01

    Decontamination of FUSRAP sites could result in the generation of large volumes (in excess of 400,000 m 3 ) of low-activity radioactive wastes (primarily contaminated soil and building materials) requiring subsequent disposal. It is likely that near-surface burial will be seriously considered as an option for disposal of these materials. A number of factors - including soil erosion - could adversely affect the long-term stability of a near-surface waste-burial site. The majority of FUSRAP sites are located in the humid eastern United States, where the principal cause of erosion is the action of water. This report examines the effect of soil erosion by water on burial-site stability based on analysis of four hypothetical near-surface burial sites. The Universal Soil Loss Equation was employed to estimate average annual soil loss from burial sites and the 1000-year effects of soil loss on the soil barrier (burial trench cap) placed over low-activity wastes. Results suggest that the land use of the burial site and the slope gradient of the burial trench cap significantly affect the rate of soil erosion. The development of measures limiting the potential land use of a burial site (e.g., mixing large rocks into the burial trench cap) may be required to preserve the integrity of a burial trench for long periods of time

  13. Stability and Hopf bifurcation in a delayed competitive web sites model

    International Nuclear Information System (INIS)

    Xiao Min; Cao Jinde

    2006-01-01

    The delayed differential equations modeling competitive web sites, based on the Lotka-Volterra competition equations, are considered. Firstly, the linear stability is investigated. It is found that there is a stability switch for time delay, and Hopf bifurcation occurs when time delay crosses through a critical value. Then the direction and stability of the bifurcated periodic solutions are determined, using the normal form theory and the center manifold reduction. Finally, some numerical simulations are carried out to illustrate the results found

  14. Savannah River Site integrated stabilization management plan. Revision 3

    International Nuclear Information System (INIS)

    Geddes, R.L.; Barone, A.; Shook, H.E.; Varner, C.E.; Rollins, R.

    1996-01-01

    On May 26, 1994, the Defense Nuclear Facilities Safety Board (DNFSB) issued Recommendation 94-1. The concern is that the halt in production of materials to be used in nuclear weapons froze the manufacturing pipeline in a state that, for safety reasons, should not be allowed to persist unremediated. This recommendation had eight specific sub-recommendations that dealt with the potential problems. Specifically, the Board expressed concern about certain liquids and solids containing fissile materials and other radioactive substances located in spent fuel storage pools, reactor basins, reprocessing canyons; and various other facilities once used for processing and weapons manufacture. The WSRC and DOE-SR acknowledges and shares the Board's concerns and has developed this Integrated Stabilization Management Plan (ISMP) to aggressively address these urgent problems in a systems engineering approach

  15. Remedial action plan and site conceptual design for stabilization of the inactive uranium mill tailings site at Ambrosia Lake, New Mexico

    International Nuclear Information System (INIS)

    Matthews, M.L.; Mitzelfelt, R.

    1991-11-01

    This Remedial Action Plan (RAP) has been developed to serve a dual purpose. It presents the series of activities that is proposed by the US Department of Energy (DOE) to stabilize and control radioactive materials at the inactive Phillips/United Nuclear uranium processing site designated as the Ambrosia Lake site in McKinley County, New Mexico. It also serves to document the concurrence of both State of New Mexico and the US Nuclear Regulatory Commission (NRC) in the remedial action. This agreement, upon execution by the DOE and the state and concurrence by NRC, becomes Appendix B of the Cooperative Agreement

  16. Soil aggregate stability and erodibility in different gully sites in parts ...

    African Journals Online (AJOL)

    This paper assesses soil aggregate stability and erodibility in different gully sites in parts of Zaria, Kaduna State, Nigeria with the aim to provide quantitative information on the variation of some soil properties and their interaction with eroding agents and how this affects soil erosion on the sites. The gullies selected are found ...

  17. Insights on the Fort Davis — Mc Donald site stability: a GPS footprint

    Science.gov (United States)

    Vigny, Christophe

    1996-05-01

    In june 1990, NASA's Crustal Dynamics Project (CDP) has established a geodetic footprint for the Satellite Laser Ranging (SLR) and Very Long Baseline Interferometry (VLBI) systems located near Fort Davis, Texas using GPS measurements. The purpose of such a footprint is to assess both the tectonic and physical stability of the main observing monuments. Included in the survey were four new monuments forming a 20 to 30 km quadrilateral, as well as four existing monuments near the McDonald Laser Ranging System (MLRS), the Harvard Radio Astronomy (HRA) 85' antenna, and the new 85' antenna of the Very Long Baseline Array (VLBA). This network was partly reoccupied by the University of Texas Austin in may 1992. Three additional sites not observed in 1990 were occupied, two of them being old monuments in the observatory area (Harvard-RM4 and VLBA-SLR), and a new monument 80 km away across the closest active fault near Valentine, Texas. Thanks to existing ties between nearby monuments in the observatory area, the comparison between the two epochs was made possible. Significant motion of more than 1 cm of any of the implied sites over a two year period can be ruled out. Despite this quite reassuring results, smaller displacements cannot be detected mainly because of the poor quality of the 1990 data. Therefore it is strongly advised that a third occupation of the footprint sites takes place in the close future. Such a survey, occuring five years after the first one and three years after the second one, should definitely answer the questions on the Fort Davis area stability at the millimeter per year level.

  18. Engineering feasibility analysis for in-situ stabilization of Burrell Township site residues

    International Nuclear Information System (INIS)

    1982-11-01

    The Burrell Township site, located in western Pennsylvania, received approximately 11,600 tons of radioactively-contaminated material in late 1956 and early 1957 from the Vitro Manufacturing Company's operations in Canonsburg, Pennsylvania. WESTON was requested to conduct an engineering study to determine the feasibility of stabilizing the site in accordance with the US Environmental Protection Agency's (EPA) interim and proposed standards (45 FR 27366--27368, April 22, 1980, and 46 FR 2556--2563, January 9, 1981). The scope of this study is limited to those alternatives that can be implemented on the site and will not require removal and offsite disposal of radioactively-contaminated material. Four alternatives for control of the radioactive material at the Burrell site were considered and evaluated, as follows: 1. Site stabilization and closure. 2. Site control and containment. 3. Waste excavation and encapsulation. 4. Waste excavation, incineration, and encapsulation. 2 refs., 32 figs., 12 tabs

  19. Engineering feasibility analysis for in-situ stabilization of Burrell Township site residues. [UMTRA

    Energy Technology Data Exchange (ETDEWEB)

    1982-11-01

    The Burrell Township site, located in western Pennsylvania, received approximately 11,600 tons of radioactively-contaminated material in late 1956 and early 1957 from the Vitro Manufacturing Company's operations in Canonsburg, Pennsylvania. WESTON was requested to conduct an engineering study to determine the feasibility of stabilizing the site in accordance with the US Environmental Protection Agency's (EPA) interim and proposed standards (45 FR 27366--27368, April 22, 1980, and 46 FR 2556--2563, January 9, 1981). The scope of this study is limited to those alternatives that can be implemented on the site and will not require removal and offsite disposal of radioactively-contaminated material. Four alternatives for control of the radioactive material at the Burrell site were considered and evaluated, as follows: 1. Site stabilization and closure. 2. Site control and containment. 3. Waste excavation and encapsulation. 4. Waste excavation, incineration, and encapsulation. 2 refs., 32 figs., 12 tabs.

  20. Characterization of active sites in zeolite catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Eckert, J. [Los Alamos National Lab., NM (United States); Bug, A. [Swarthmore Coll., PA (United States); Nicol, J.M. [MOLTECH (United States)] [and others

    1997-11-01

    This is the final report of a three-year, Laboratory Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL). Atomic-level details of the interaction of adsorbed molecules with active sites in catalysts are urgently needed to facilitate development of more effective and/or environmentally benign catalysts. To this end the authors have carried out neutron scattering studies combined with theoretical calculations of the dynamics of small molecules inside the cavities of zeolite catalysts. The authors have developed the use of H{sub 2} as a probe of adsorption sites by observing the hindered rotations of the adsorbed H{sub 2} molecule, and they were able to show that an area near the four-rings is the most likely adsorption site for H{sub 2} in zeolite A while adsorption of H{sub 2} near cations located on six-ring sites decreases in strength as Ni {approximately} Co > Ca > Zn {approximately} Na. Vibrational and rotational motions of ethylene and cyclopropane adsorption complexes were used as a measure for zeolite-adsorbate interactions. Preliminary studies of the binding of water, ammonia, and methylamines were carried out in a number of related guest-host materials.

  1. Membrane Stabilizing Activity And Phytochemistry Of Hibiscus rosa ...

    African Journals Online (AJOL)

    The human erythrocyte membrane stabilizing activity of saline extract of Hibiscus rosa-sinensis leaves was investigated as part of efforts at validating its use as anti-arthritic and anti-inflammatory agent. The results of the membrane stabilizing activity of the extract, when compared to two non-steroidal anti-inflammatory drugs ...

  2. An assessment of different atmospheric stability methods for annual atmospheric dispersion factors at a coastal site

    International Nuclear Information System (INIS)

    Bagavathsingh, A.; Rakesh, P.T.; Srinivas, C.V.; Baskaran, R.; Venkatraman, B.

    2018-01-01

    The meteorological data is used for routine radiological release consequence analysis, real time consequence assessments of accidental releases of radiological effluents and design basis accidental analysis in a nuclear plant site. For dispersion estimate, it is often required to specify the type of stability and/or turbulence conditions in which diffusion of pollutants would occur. Stability indicates the degree of turbulence and thus the atmospheric mixing. Intensity of turbulence and dispersion of pollutant releases in to the lower atmosphere are strongly dependent on the local winds as well as resistance of atmosphere to vertical mixing which is called atmospheric stability. Three different methods of atmospheric stability based on Standard deviation of wind direction (σθ), temperature gradient and Bulk Richardson (Rib) number are used to compute stability over Kalpakkam site using hourly meteorological data. All the three methods of estimating atmospheric stability are compared with M-O similarity based method. Different atmospheric stability methods were analyzed to estimate the annual average atmospheric dispersion factors at Kalpakkam coastal site for the year 2016

  3. Multiple binding of thallium and rubidium to potassium-activated yeast aldehyde dehydrogenase. Influences on tertiary structure, stability and catalytic activity.

    Science.gov (United States)

    Bostian, K A; Betts, G F; Man, W K; Hughes, M N

    1982-01-01

    Univalent cation activators of aldehyde dehydrogenase have dual effects, both interpreted as cation-induced or -stabilized conformation changes. These two processes are differentiated by the time scales of their associated changes in activity. Using Tl+ as an activator, under certain conditions, the slower change in activity saturates at a Tl+ concentration which is only 0.1 Ks for the faster change. This, together with evidence for cation-induced rather than cation-stabilized conformation changes, is used to propose separate binding sites for cations responsible for the two activation processes. Equilibrium dialysis indicates 4 binding sites per active site for Rb+ or 6 sites for Tl+. At least one of the additional sites for Tl+ is an inhibitory site which has been differentiated from the activator sites on the basis of steady-state and pre-steady-state kinetic data. PMID:6758767

  4. First principles study of structural stability and site preference in Co3 (W,X

    Directory of Open Access Journals (Sweden)

    Joshi Sri Raghunath

    2014-01-01

    Full Text Available Since the discovery [1] of γ′ precipitate (L12 – Co3(Al, W in the Co-Al-W ternary system, there has been an increased interest in Co-based superalloys. Since these alloys have two phase microstructures (γ + γ′ similar to Ni-based superalloys [2], they are viable candidates in high temperature applications, particularly in land-based turbines. The role of alloying on stability of the γ′ phase has been an active area of research. In this study, electronic structure calculations were done to probe the effect of alloying in Co3W with L12 structure. Compositions of type Co3(W,X, (where X/Y = Mn, Fe, Ni, Pt, Cr , Al, Si, V, W, Ta, Ti, Nb, Hf, Zr and Mo were studied. Effect of alloying on equilibrium lattice parameters and ground state energies was used to calculate Vegard's coefficients and site preference related data. The effect of alloying on the stability of the L12 structure vis a vis other geometrically close packed ordered structures was also studied for a range of Co3X compounds. Results suggest that the penchant of element for the W sublattice can be predicted by comparing heats of formation of Co3X in different structures.

  5. Stability of multi orifice active tilting-pad journal bearings

    DEFF Research Database (Denmark)

    Haugaard, Asger M.; Santos, Ilmar

    2010-01-01

    The stability properties of actively lubricated tilting-pad journal bearings are investigated theoretically. The bearing preload factor and control system gains are varied, and stable and unstable regions are identified. It is seen, that the control system influences bearing stability, and that t......The stability properties of actively lubricated tilting-pad journal bearings are investigated theoretically. The bearing preload factor and control system gains are varied, and stable and unstable regions are identified. It is seen, that the control system influences bearing stability...

  6. New stability and stabilization criteria for fuzzy neural networks with various activation functions

    Science.gov (United States)

    Mathiyalagan, K.; Sakthivel, R.; Anthoni, S. Marshal

    2011-07-01

    In this paper, the stability analysis and control design of Takagi-Sugeno (TS) fuzzy neural networks with various activation functions and continuously distributed time delays are addressed. By implementing the delay-fractioning technique together with the linear matrix inequality (LMI) approach , a new set of sufficient conditions is derived in terms of linear matrix inequalities, which ensure the stability of the considered fuzzy neural networks. Further, based on the above-mentioned techniques, a control law with an appropriate gain control matrix is derived to achieve stabilization of the fuzzy neural networks. In addition, the results are extended to the study of the stability and stabilization results for TS fuzzy uncertain neural networks with parameter uncertainties. The stabilization criteria are obtained in terms LMIs and hence the gain control matrix can be easily determined by the MATLAB LMI control toolbox. Two numerical examples with simulation results are given to illustrate the effectiveness of the obtained result.

  7. Remedial Action Plan and site design for stabilization of the inactive uranium mill tailings site at Gunnison, Colorado

    International Nuclear Information System (INIS)

    1992-10-01

    The US Environmental Protection Agency (EPA) has established health and environmental protection regulations to correct and prevent groundwater contamination resulting from processing activities at inactive uranium milling sites (40 CFR 192). The US Department of Energy (DOE) is responsible for assessing the inactive uranium processing sites. The DOE has determined this assessment shall include information on hydrogeologic site characterization. This document contains appendices to Attachment 3, Groundwater Hydrology Report included are calculations

  8. Development of corrective measures and site stabilization technologies for shallow land burial facilities at semiarid sites

    International Nuclear Information System (INIS)

    Nyhan, J.W.; Abeele, W.V.

    1986-01-01

    The overall purpose of the corrective measures task performed for the National Low-Level Waste Management Program has been to develop and test methods that can be used to correct any actual or anticipated problems with new and existing shallow land burial (SLB) sites in a semiarid environment. These field tests have not only evaluated remedial actions, but have also investigated phenomena suspected of being a possible problem at semiarid SLB sites. The approach we have taken in developing remedial action and site closure technologies for low-level waste sites is to recognize that physical and biological processes affecting site integrity are interdependent, and therefore, cannot be treated as separate problems. The field experiments performed for this task were to identify, evaluate, and model erosion control technologies, field test second generation biointrusion barriers, determine by field experiments the extent of upward radionuclide migration due to moisture cycling, and measure the effects of subsidence on remedial action of other system components. Progress made in each of these research areas is described

  9. Slope stability and bearing capacity of landfills and simple on-site test methods.

    Science.gov (United States)

    Yamawaki, Atsushi; Doi, Yoichi; Omine, Kiyoshi

    2017-07-01

    This study discusses strength characteristics (slope stability, bearing capacity, etc.) of waste landfills through on-site tests that were carried out at 29 locations in 19 sites in Japan and three other countries, and proposes simple methods to test and assess the mechanical strength of landfills on site. Also, the possibility of using a landfill site was investigated by a full-scale eccentric loading test. As a result of this, landfills containing more than about 10 cm long plastics or other fibrous materials were found to be resilient and hard to yield. An on-site full scale test proved that no differential settlement occurs. The repose angle test proposed as a simple on-site test method has been confirmed to be a good indicator for slope stability assessment. The repose angle test suggested that landfills which have high, near-saturation water content have considerably poorer slope stability. The results of our repose angle test and the impact acceleration test were related to the internal friction angle and the cohesion, respectively. In addition to this, it was found that the air pore volume ratio measured by an on-site air pore volume ratio test is likely to be related to various strength parameters.

  10. Structure and Reactivity of the Phosphotriesterase Active Site

    National Research Council Canada - National Science Library

    Krauss, Morris

    2002-01-01

    ... wide range of theoretical structures can be optimized for metal substituted and mutant active sites. The structural behavior of the active site is modeled using a new effective potential for representing the protein molecular environment...

  11. DNFSB Recommendation 94-1 Hanford site integrated stabilization management plan, volumes 1 and 2

    International Nuclear Information System (INIS)

    Gerber, E.W.

    1996-01-01

    This document comprises the Hanford Site Integrated Stabilization Management Plan (SISMP). This document describes the DOE's plans at the Hanford Site to address concerns identified in Defense Nuclear Facilites Safety Board (DNFSB) Recommendation 94-1. This document also identifies plans for other spent nuclear fuel (SNF) inventories at the Hanford Site which are not within the scope of DNFSB Recommendation 94-1 for reference purposes because of their interrelationship with plans for SNF within the scope of DNFSB Recommendation 94-1. The SISMP was also developed to assist DOE in initial formulation of the Research and Development Plan and the Integrated Facilities Plan

  12. Montezuma Creek Stability Evaluation at Site of Former Monticello Tailings Pile; TOPICAL

    International Nuclear Information System (INIS)

    Korte, N.

    2001-01-01

    This report documents the results of an evaluation of stream stability for Montezuma Creek downstream of the former uranium and vanadium millsite at Monticello, Utah. The work was performed by personnel from Oak Ridge National Laboratory's (ORNL's) Environmental Technology Section (ETS). ORNL/ETS was the Independent Verification Contractor (IVC) for the Monticello projects, and it established independent verification strategies that provided the U.S. Department of Energy (DOE) with a third-party assessment of whether remedial action had effectively reduced levels of contamination and whether supporting documentation that described the remediation was adequate. The DOE regulation 10 CFR 1022, which implements Executive Orders 11988 and 11990 for the protection of wetlands and floodplains, provided the regulatory rationale for the activity. This report documents both the impact of millsite remedial activities and postremediation conditions of Montezuma Creek. The scientific rationale for the stream survey was that conventional engineering practices do not adequately account for varying hydrologic regimes nor do they address the entire riparian zone as an interrelated unit. As a result, modifications to streams consistently cause damage to the environment by increasing erosion and sedimentation. Field activities included the establishment of permanent cross sections and periodic measurements and surveys of physical characteristics. The data demonstrated an increase in downstream stream bank erosion when activities at the millsite were greatest. Note, however, that agricultural practices have also contributed to erosion and bank instability. Nevertheless, an increase in fine sediment and bank recession were correlated to the construction. In addition, the project documented the failure of best management practices such as silt fences, to control sediment loss. Furthermore, conventional engineering designs were used to reroute Montezuma Creek, an action that will

  13. Modeling, Stability Analysis and Active Stabilization of Multiple DC-Microgrids Clusters

    DEFF Research Database (Denmark)

    Shafiee, Qobad; Dragicevic, Tomislav; Vasquez, Juan Carlos

    2014-01-01

    . This model can be also used to synthesis and study dynamics of control loops in dc MGs and also dc MG clusters. An active stabilization method is proposed to be implemented as a dc active power filter (APF) inside the MGs in order to not only increase damping of dc MGs at the presence of CPLs but also......DC microgrids (MGs), as an alternative option, have attracted increasing interest in recent years due to many potential advantages as compare to the ac system. Stability of these systems can be an important issue under high penetration of load converters which behaves as constant power loads (CPLs......), and more especially during interconnection with other MGs, creating dc MG clusters. This paper develops a small signal model for dc MGs from the control point of view, in order to study stability analysis and investigate effects of CPLs and line impedances between the MGs on stability of these systems...

  14. Neighborhood Stabilization Program (NSP) Activities by Tract

    Data.gov (United States)

    Department of Housing and Urban Development — The data being displayed are census tract level counts of NSP-funded activities and is derived from an extract of HUD's Community Planning and Development’s (CPD)...

  15. Maxey Flats low-level waste disposal site closure activities

    International Nuclear Information System (INIS)

    Haight, C.P.; Mills, D.; Razor, J.E.

    1987-01-01

    The Maxey Flats Radioactive Waste Disposal Facility in Fleming County, Kentucky is in the process of being closed. The facility opened for commercial business in the spring of 1963 and received approximately 4.75 million cubic feet of radioactive waste by the time it was closed in December of 1977. During fourteen years of operation approximately 2.5 million curies of by-product material, 240,000 kilograms of source material, and 430 kilograms of special nuclear material were disposed. The Commonwealth purchased the lease hold estate and rights in May 1978 from the operating company. This action was taken to stabilize the facility and prepare it for closure consisting of passive care and monitoring. To prepare the site for closure, a number of remedial activities had to be performed. The remediation activities implemented have included erosion control, surface drainage modifications, installation of a temporary plastic surface cover, leachate removal, analysis, treatment and evaporation, US DOE funded evaporator concentrates solidification project and their on-site disposal in an improved disposal trench with enhanced cover for use in a humid environment situated in a fractured geology, performance evaluation of a grout injection demonstration, USGS subsurface geologic investigation, development of conceptual closure designs, and finally being added to the US EPA National Priority List for remediation and closure under Superfund. 13 references, 3 figures

  16. Remedial Action Plan and site design for stabilization of the inactive uranium mill tailings site at Rifle, Colorado

    International Nuclear Information System (INIS)

    1990-02-01

    This document has been structured to provide a comprehensive understanding of the remedial action proposed for the Rifle sites. That remedial action consists of removing approximately 4,185,000 cubic yards (cy) of tailings and contaminated materials from their current locations, transporting, and stabilizing the tailings material at the Estes Gulch disposal site, approximately six miles north of Rifle. The tailings and contaminated materials are comprised of approximately 597,000 cy from Old Rifle, 3,232,000 cy from New Rifle, and 322,000 cy from vicinity properties and about 34,000 cy from demolition. The remedial action plan includes specific design requirements for the detailed design and construction of the remedial action. An extensive amount of data and supporting information have been generated for this remedial action and cannot all be incorporated into this document. Pertinent information and data are included with reference given to the supporting documents

  17. Remedial Action Plan for stabilization of the inactive uraniferous lignite processing sites at Belfield and Bowman, North Dakota

    International Nuclear Information System (INIS)

    1990-12-01

    This remedial action plan (RAP) has been developed to serve a threefold purpose. It presents the series of activities that are proposed by the US Department of Energy (DOE) to accomplish long-term stabilization and control of radioactive materials at the inactive uraniferous lignite processing sites at Belfield and near Bowman (at the former Griffin town site), North Dakota. It provides a characterization of the present conditions of the sites. It also serves to document the concurrence of the state of North Dakota and the US Nuclear Regulatory Commission (NRC) in the remedial action. This agreement, upon execution by the DOE and the state of North Dakota and concurrence by the NRC, becomes Appendix B of the Cooperative Agreement

  18. Trunk muscle activity in healthy subjects during bridging stabilization exercises

    Directory of Open Access Journals (Sweden)

    Vanderstraeten Guy G

    2006-09-01

    Full Text Available Abstract Background Trunk bridging exercises are often used as therapeutic exercises for lumbopelvic stabilization. These exercises focus on the retraining of muscle coordination patterns in which optimal ratios between local segmental stabilizing and global torque producing muscle activity are assumed to be essential. However, a description of such ratios is lacking. The purpose of this study was to investigate both relative (as a percentage of maximal voluntary isometric contraction muscle activity levels and ratios of local to global muscle activity, during bridging stabilization exercises. Methods Thirty healthy university students (15 men, 15 women with a mean age of 19.6 year volunteered to perform 3 bridging exercises (single bridging, ball bridge and unilateral bridging. The surface electromyographic activity of different trunk muscles was evaluated on both sides. Results During all bridging exercises, the ratio of the internal oblique to the rectus abdominis was very high due to minimal relative activity of the rectus abdominis. In general, the ratio of the internal/external abdominal oblique activity was about 1. However, during the unilateral bridging exercise, the ipsilateral internal/external abdominal oblique activity ratio was 2.79 as a consequence of the significant higher relative activity of the internal oblique compared to the external oblique. The relative muscle activity and the ratios of the back muscles demonstrated similar activity levels for all back muscles, resulting in ratios about 1. Conclusion Both the minimal relative activity of the rectus abdominis and the high internal oblique to the rectus abdominis activity ratio reported in the present study are in accordance with results of other trunk stabilization exercises. The relative muscle activity and the ratio of the abdominal obliques seem to alter depending on the task and the presumable need for stability. The findings concerning the relative muscle activity and

  19. An active interferometer-stabilization scheme with linear phase control

    DEFF Research Database (Denmark)

    Vardhan Krishnamachari, Vishnu; Andresen, Esben Ravn; Potma, Eric Olaf

    2006-01-01

    We report a simple and robust computer-based active interferometer stabilization scheme which does not require modulation of the interfering beams and relies on an error signal which is linearly related to the optical path difference. In this setup, a non-collinearly propagating reference laser...... beam stabilizes the interference output of the laser light propagating collinearly through the interferometer. This stabilization scheme enables adjustable phase control with 20 ms switching times in the range from 0.02π radians to 6π radians at 632.8 nm....

  20. Peptide fibrils with altered stability, activity, and cell selectivity

    OpenAIRE

    Chen, Long; Liang, Jun F.

    2013-01-01

    Peptides have some unique and superior features compared to proteins. However, the use of peptides as therapeutics is hampered by their low stability and cell selectivity. In this study, a new lytic peptide (CL-1, FLGALFRALSRLL) was constructed. Under the physiological condition, peptide CL-1 self-assembled into dynamically stable aggregates with fibrils-like structures. Aggregated CL-1 demonstrated dramatically altered activity and stability in comparison with single molecule CL-1 and other ...

  1. Promoter proximal polyadenylation sites reduce transcription activity

    DEFF Research Database (Denmark)

    Andersen, Pia Kjølhede; Lykke-Andersen, Søren; Jensen, Torben Heick

    2012-01-01

    , which in turn causes reduced transcription. Functional depletion of U1 snRNP in the context of the wild-type SD triggers the same CpA event accompanied by decreased RNA levels. Thus, in accordance with recent findings, U1 snRNP can shield premature pA sites. The negative impact of unshielded pA sites...

  2. Metabolic stabilization of acetylcholine receptors in vertebrate neuromuscular junction by muscle activity

    International Nuclear Information System (INIS)

    Rotzler, S.; Brenner, H.R.

    1990-01-01

    The effects of muscle activity on the growth of synaptic acetylcholine receptor (AChR) accumulations and on the metabolic AChR stability were investigated in rat skeletal muscle. Ectopic end plates induced surgically in adult soleus muscle were denervated early during development when junctional AChR number and stability were still low and, subsequently, muscles were either left inactive or they were kept active by chronic exogenous stimulation. AChR numbers per ectopic AChR cluster and AChR stabilities were estimated from the radioactivity and its decay with time, respectively, of end plate sites whose AChRs had been labeled with 125 I-alpha-bungarotoxin (alpha-butx). The results show that the metabolic stability of the AChRs in ectopic clusters is reversibly increased by muscle activity even when innervation is eliminated very early in development. 1 d of stimulation is sufficient to stabilize the AChRs in ectopic AChR clusters. Muscle stimulation also produced an increase in the number of AChRs at early denervated end plates. Activity-induced cluster growth occurs mainly by an increase in area rather than in AChR density, and for at least 10 d after denervation is comparable to that in normally developing ectopic end plates. The possible involvement of AChR stabilization in end plate growth is discussed

  3. Mechanisms of antibacterial activity and stability of silver ...

    Indian Academy of Sciences (India)

    Abstract. Nanomaterials with high stability and efficient antibacterial activity are of considerable interest. The preparation of silver nanoparticles (AgNPs) on titania coatings and their effective antibacterial activity against. Staphylococcus aureus ATCC 6538 were reported. Titanium dioxide (TiO2) coatings with AgNPs were ...

  4. Revegetation/rock cover for stabilization of inactive U-tailings sites

    International Nuclear Information System (INIS)

    Beedlow, P.A.; Cadwell, L.L.

    1982-01-01

    Soil placed over any sealant/barrier system can provide a protective mantle if the soil is not lost by erosion. Vegetation is an attractive choice for controlling erosion because it can provide an economic self-renewing cover that serves to reduce erosion by both wind and water. Vegetation alone, however, may not adequately stabilize the surface in extremely arid areas. In those areas, a properly designed surface treatment of rock cover, perhaps in conjunction with vegetation, may be necessary to stabilize the tailings surfaces. The objective of this program is to establish guidelines for surface stabilization that are compatible with sealant/barrier systems and that are suited to soils and climates at inactive uranium mill tailings sites. These guidelines will provide the means to estimate potential vegetation cover, potential erosion, effects of surface treatments on sealant/barrier systems, and costs of vegetation and rock covers. Methods for establishing vegetation on sealed tailings will also be provided

  5. Existence and stability of 3-site breathers in a triangular lattice

    International Nuclear Information System (INIS)

    Koukouloyannis, Vassilis; MacKay, Robert S

    2005-01-01

    We find conditions for existence and stability of various types of discrete breather concentrated around three central sites in a triangular lattice of one-dimensional Hamiltonian oscillators with on-site potential and nearest-neighbour coupling. In particular, we confirm that it can support non-reversible breather solutions, despite the time-reversible character of the system. They carry a net energy flux and can be called 'vortex breathers'. We prove that there are parameter regions for which they are linearly stable, for example in a lattice consisting of coupled Morse oscillators, whereas the related reversible breathers are unstable. Thus non-reversible breathers can be physically relevant

  6. Evaluation of the geologic relations and seismotectonic stability of the Yucca Mountain Area Nevada Nuclear Waste Site Investigation (NNWSI)

    International Nuclear Information System (INIS)

    1995-01-01

    This report provides a summary of progress for the project open-quotes Evaluation of the Geologic Relations and Seismotectonic Stability of the Yucca Mountain Area, Nevada Nuclear Waste Site Investigation (NNWSI).close quotes A similar report was previously provided for the period of 1 October 1993 to 30 September 1994. The report initially covers the activities of the General Task and is followed by sections that describe the progress of the other ongoing Tasks which are listed below. Task 1: Quaternary Tectonics Task 3: Mineral Deposits, Volcanic Geology Task 4: Seismology Task 5: Tectonics Task 8: Basinal Studies

  7. Engineering Lipases: walking the fine line between activity and stability

    Science.gov (United States)

    Dasetty, Siva; Blenner, Mark A.; Sarupria, Sapna

    2017-11-01

    Lipases are enzymes that hydrolyze lipids and have several industrial applications. There is a tremendous effort in engineering the activity, specificity and stability of lipases to render them functional in a variety of environmental conditions. In this review, we discuss the recent experimental and simulation studies focused on engineering lipases. Experimentally, mutagenesis studies have demonstrated that the activity, stability, and specificity of lipases can be modulated by mutations. It has been particularly challenging however, to elucidate the underlying mechanisms through which these mutations affect the lipase properties. We summarize results from experiments and molecular simulations highlighting the emerging picture to this end. We end the review with suggestions for future research which underscores the delicate balance of various facets in the lipase that affect their activity and stability necessitating the consideration of the enzyme as a network of interactions.

  8. Activities on the site during construction phase

    International Nuclear Information System (INIS)

    Fickel, O.F.

    1977-01-01

    A survey is given of the work done on the site from site-opening till turn over of the plant to the client. After a short introduction to time schedules, manpower on site, site facilities and civil work and constructions, the commissioning and trial operation phase is discussed in detail. This phase begins with finishing the assembly of individual systems and components and ends with the trial operation and the acceptance measurement. During this period the subsystems are started-up in a useful sequence, first from cold, then from hot conditions and are finally operated as a total with nuclear energy. The single steps are: a) commissioning of indivudal systems; b) hot functional test 1 (without fuels) c) baseline inspection at the reactor pressure vessel; d) hot functional test 2 (with fuels); e) preparation for first criticality; f) postcriticality test program; g) trial operation: h) acceptance measurement. (HP) [de

  9. Remedial action plan and site design for stabilization of the inactive uranium mill tailings site at Lowman, Idaho

    International Nuclear Information System (INIS)

    1991-09-01

    The US Environmental Protection Agency (EPA) has established health and environmental regulations to correct and prevent groundwater contamination resulting from former uranium processing activities at inactive uranium processing sites (40 CFR 192). According to the Uranium Mill Tailings Radiation Control Act of 1978 (UMTRCA), the US Department of Energy (DOE) is responsible for assessing the inactive uranium processing sites. The DOE has decided that each assessment shall include information on hydrogeologic site characterization. The water resources protection strategy that describes how the proposed action will comply with the EPA groundwater protection standards is presented in Attachment 4. Site characterization activities discussed in this section include: Definition of the hydrogeologic characteristics of the environment, including hydrostratigraphy, aquifer parameters, areas of aquifer recharge and discharge, potentiometric surfaces, and groundwater velocities. Definition of background groundwater quality and comparison with the proposed EPA groundwater protection standards. Evaluation of the physical and chemical characteristics of the contaminant source and/or residual radioactive materials. Definition of existing groundwater contamination by comparison with the EPA groundwater protection standards. Description of the geochemical processes that affect the downward migration of the source contaminants at the processing site. Description of water resource utilization, including availability, current and future use and value, and alternate water supplies

  10. Substituent Effects on the Stability and Antioxidant Activity of Spirodiazaselenuranes

    Directory of Open Access Journals (Sweden)

    Devappa S. Lamani

    2015-07-01

    Full Text Available Spirodiazaselenuranes are structurally interesting compounds and the stability of these compounds depends highly on the nature of the substituents attached to the nitrogen atoms. Aromatic substituents are known to play important roles in stabilizing the Se-N bonds in spiro compounds. In this study, several spirodiazaselenuranes are synthesized by introducing benzylic and aliphatic substituents to understand their effect on the stability of the Se-N bonds and the antioxidant activity. Replacement of phenyl substituent by benzyl/alkyl groups significantly reduces the stability of the spirodiazaselenuranes and slows down the oxidative cyclization process. The selenium centre in the spiro compounds undergoes further oxidation to produce the corresponding selenurane oxides, which are stable at room temperature. Comparison of the glutathione peroxidase (GPx mimetic activity of the compounds showed that the diaryl selenides having heterocyclic rings are significantly more active due to the facile oxidation of the selenium centre. However, the activity is reduced significantly for compounds having aliphatic substituents. In addition to GPx activity, the compounds also inhibit peroxynitrite-mediated nitration and oxidation reaction of protein and small molecules, respectively. The experimental observations suggest that the antioxidant activity is increased considerably upon substitution of the aromatic group with the benzylic/aliphatic substituents on the nitrogen atoms.

  11. Superior acidic catalytic activity and stability of Fe-doped HTaWO6 nanotubes

    KAUST Repository

    Liu, He

    2017-07-26

    Fe-doped HTaWO6 (H1-3xFexTaWO6, x = 0.23) nanotubes as highly active solid acid catalysts were prepared via an exfoliation-scrolling-exchange process. The specific surface area and pore volume of undoped nanotubes (20.8 m2 g-1, 0.057 cm3 g-1) were remarkably enhanced through Fe3+ ion-exchange (>100 m2 g-1, 0.547 cm3 g-1). Doping Fe ions into the nanotubes endowed them with improved thermal stability due to the stronger interaction between the intercalated Fe3+ ions and the host layers. This interaction also facilitated the preservation of effective Brønsted acid sites and the generation of new acid sites. The integration of these functional roles resulted in Fe-doped nanotubes with high acidic catalytic activities in the Friedel-Crafts alkylation of anisole and the esterification of acetic acid. Facile accessibility to active sites, generation of effective Brønsted acid sites, high stability of the tubular structure and strong acid sites were found to synergistically contribute to the excellent acidic catalytic efficiency. Additionally, the activity of cycled nanocatalysts can be easily recovered through annealing treatment.

  12. Remedial action plan and site design for stabilization of the inactive uranium processing site at Naturita, Colorado. Remedial action selection report, Attachment 2, Geology report: Preliminary final

    Energy Technology Data Exchange (ETDEWEB)

    1993-08-01

    The uranium processing site near Naturita, Colorado, is one of 24 inactive uranium mill sites designated to be cleaned up by the US Department of Energy (DOE) under the Uranium Mill Tailings Radiation Control Act of 1978 (UMTRCA), Public Law 95-604. Part of the UMTRCA requires that the US Nuclear Regulatory Commission (NRC) concur with the DOE`s remedial action plan (RAP) and certify that the remedial action conducted at the site complies with the standards promulgated by the US Environmental Protection Agency (EPA). Included in the RAP is this Remedial Action Selection Report (RAS), which serves two purposes. First, it describes the activities that are proposed by the DOE to accomplish remediation and long-term stabilization and control of the radioactive materials at the inactive uranium processing site near Naturita, Colorado. Second, this document and the rest of the RAP, upon concurrence and execution by the DOE, the state of Colorado, and the NRC, become Appendix B of the cooperative agreement between the DOE and the State of Colorado.

  13. Remedial Action Plan and site design for stabilization of the inactive uranium mill tailings site at Durango, Colorado: Remedial action selection report

    International Nuclear Information System (INIS)

    1991-12-01

    The uranium mill tailings site near Durango, Colorado, was one of 24 inactive uranium mill sites designated to be remediated by the US Department of Energy (DOE) under the Uranium Mill Tailings Radiation Control Act of 1978 (UMTRCA). Part of the UMTRCA requires that the US Nuclear Regulatory Commission (NRC) concur with the DOE's Remedial Action Plan (RAP) and certify that the remedial action conducted at the site complies with the standards promulgated by the US Environmental Protection Agency (EPA). Included in the RAP is this Remedial Action Selection Report (RAS), which has been developed to serve a two-fold purpose. First, it describes the activities that have been conducted by the DOE to accomplish remediation and long-term stabilization and control of the radioactive materials at the inactive uranium mill processing site near Durango, Colorado. Secondly, this document and the rest of the RAP, upon concurrence and execution by the DOE, the State of Colorado, and the NRC, become Appendix B of the Cooperative Agreement between the DOE and the State of Colorado

  14. DNFSB Recommendation 94-1 Hanford Site Integrated Stabilization Management Plan. Volume 1

    International Nuclear Information System (INIS)

    Gerber, E.W.

    1995-10-01

    The US Department of Energy (DOE) has developed an Integrated Program Plan (IPP) to address concerns identified in Defense Nuclear Facilities Safety Board Recommendation 94-1. The IPP describes the actions that DOE plans to implement at its various sites to convert excess fissile materials to forms or conditions suitable for safe interim storage. The baseline IPP was issued as DOE's Defense Nuclear Facilities Safety Board (DNFSB) Recommendation 94-1 Implementation Plan (IP), which was transmitted to the DNFSB on February 28, 1995. The IPP is being further developed to include complex-wide requirements for research and development and a long-range facility requirements section. The planned additions to the baseline IPP are being developed based on a systems engineering approach that integrates facilities and capabilities at the various DOE sites and focuses on attaining safe interim storage with minimum safety risks and environmental impacts. Each affected DOE site has developed a Site Integrated Stabilization Management Plan (SISMP) to identify individual site plans to implement the DNFSB Recommendation 94-1 and to provide a basis for formulating planned additions to the IPP. The SISMPs were developed based on the objectives, requirements, and commitments identified in the baseline DNFSB Recommendation 94-1 IPP. The SISMPs will be periodically updated to reflect improved integration between DOE sites as identified during the IPP systems engineering evaluations

  15. DNFSB Recommendation 94-1 Hanford Site Integrated Stabilization Management Plan. Volume 1

    Energy Technology Data Exchange (ETDEWEB)

    Gerber, E.W.

    1995-10-01

    The US Department of Energy (DOE) has developed an Integrated Program Plan (IPP) to address concerns identified in Defense Nuclear Facilities Safety Board Recommendation 94-1. The IPP describes the actions that DOE plans to implement at its various sites to convert excess fissile materials to forms or conditions suitable for safe interim storage. The baseline IPP was issued as DOE`s Defense Nuclear Facilities Safety Board (DNFSB) Recommendation 94-1 Implementation Plan (IP), which was transmitted to the DNFSB on February 28, 1995. The IPP is being further developed to include complex-wide requirements for research and development and a long-range facility requirements section. The planned additions to the baseline IPP are being developed based on a systems engineering approach that integrates facilities and capabilities at the various DOE sites and focuses on attaining safe interim storage with minimum safety risks and environmental impacts. Each affected DOE site has developed a Site Integrated Stabilization Management Plan (SISMP) to identify individual site plans to implement the DNFSB Recommendation 94-1 and to provide a basis for formulating planned additions to the IPP. The SISMPs were developed based on the objectives, requirements, and commitments identified in the baseline DNFSB Recommendation 94-1 IPP. The SISMPs will be periodically updated to reflect improved integration between DOE sites as identified during the IPP systems engineering evaluations.

  16. A review of heat-treatment effects on activity and stability of PEM fuel cell catalysts for oxygen reduction reaction

    Energy Technology Data Exchange (ETDEWEB)

    Bezerra, Cicero W.B. [Institute for Fuel Cell Innovation, National Research Council of Canada, Vancouver, BC V6T 1W5 (Canada); Department of Chemistry, Universidade Federal do Maranhao, Av. dos Portugueses, S/N 65.080-040 Sao Luis, MA (Brazil); Zhang, Lei; Liu, Hansan; Lee, Kunchan; Wang, Haijiang; Zhang, Jiujun [Institute for Fuel Cell Innovation, National Research Council of Canada, Vancouver, BC V6T 1W5 (Canada); Marques, Aldalea L.B. [Department of Technology Chemistry, Universidade Federal do Maranhao, Sao Luis, MA (Brazil); Marques, Edmar P. [Department of Chemistry, Universidade Federal do Maranhao, Av. dos Portugueses, S/N 65.080-040 Sao Luis, MA (Brazil)

    2007-11-15

    This paper reviews over 120 papers regarding the effect of heat treatment on the catalytic activity and stability of proton exchange membrane (PEM) fuel cell catalysts. These catalysts include primarily unsupported and carbon-supported platinum (Pt), Pt alloys, non-Pt alloys, and transition metal macrocycles. The heat treatment can induce changes in catalyst properties such as particle size, morphology, dispersion of the metal on the support, alloying degree, active site formation, catalytic activity, and catalytic stability. The optimum heat-treatment temperature and time period are strongly dependent on the individual catalyst. With respect to Pt-based catalysts, heat treatment can induce particle-size growth, better alloying degree, and changes in the catalyst surface morphology from amorphous to more ordered states, all of which have a remarkable effect on oxygen reduction reaction (ORR) activity and stability. However, heat treatment of the catalyst carbon supports can also significantly affect the ORR catalytic activity of the supported catalyst. Regarding non-noble catalysts, in particular transition metal macrocycles, heat treatment is also important in ORR activity and stability improvement. In fact, heat treatment is a necessary step for introducing more active catalytic sites. For metal chalcogenide catalysts, it seems that heat treatment may not be necessary for catalytic activity and stability improvement. More research is necessary to improve our fundamental understanding and to develop a new strategy that includes innovative heat-treatment processes for enhancing fuel cell catalyst activity and stability. (author)

  17. A review of heat-treatment effects on activity and stability of PEM fuel cell catalysts for oxygen reduction reaction

    Science.gov (United States)

    Bezerra, Cicero W. B.; Zhang, Lei; Liu, Hansan; Lee, Kunchan; Marques, Aldaléa L. B.; Marques, Edmar P.; Wang, Haijiang; Zhang, Jiujun

    This paper reviews over 120 papers regarding the effect of heat treatment on the catalytic activity and stability of proton exchange membrane (PEM) fuel cell catalysts. These catalysts include primarily unsupported and carbon-supported platinum (Pt), Pt alloys, non-Pt alloys, and transition metal macrocycles. The heat treatment can induce changes in catalyst properties such as particle size, morphology, dispersion of the metal on the support, alloying degree, active site formation, catalytic activity, and catalytic stability. The optimum heat-treatment temperature and time period are strongly dependent on the individual catalyst. With respect to Pt-based catalysts, heat treatment can induce particle-size growth, better alloying degree, and changes in the catalyst surface morphology from amorphous to more ordered states, all of which have a remarkable effect on oxygen reduction reaction (ORR) activity and stability. However, heat treatment of the catalyst carbon supports can also significantly affect the ORR catalytic activity of the supported catalyst. Regarding non-noble catalysts, in particular transition metal macrocycles, heat treatment is also important in ORR activity and stability improvement. In fact, heat treatment is a necessary step for introducing more active catalytic sites. For metal chalcogenide catalysts, it seems that heat treatment may not be necessary for catalytic activity and stability improvement. More research is necessary to improve our fundamental understanding and to develop a new strategy that includes innovative heat-treatment processes for enhancing fuel cell catalyst activity and stability.

  18. Activity, stability and kinetic parameters for α-chymotrypsin catalysed ...

    Indian Academy of Sciences (India)

    activity of α-CT with various degrees of hydration to varying AOT concentration and its stability in RM medium. ... and organic solvents (ethanol and isooctane) were procured from Qualigens Fine Chemicals (Mumbai, ... strate, the PNPA was prepared in pure ethanol. Stock solutions of AOT RMs containing Tris/HCl buffer in.

  19. Activity, stability and kinetic parameters for α-chymotrypsin catalysed ...

    Indian Academy of Sciences (India)

    under the effect of nonionic and zwitterionic surfactants to obtain an in depth knowledge of enzymatic reaction in micellar media. We propose the advances in catalytic activity of α-CT with various degrees of hydration to varying AOT concentration and its stability in RM medium. The hydrolysis of PNPA catalysed by α-CT.

  20. Role of water balance in the long-term stability of hazardous waste site cover treatments

    International Nuclear Information System (INIS)

    Barnes, F.J.; Rodgers, J.C.; Trujillo, G.

    1986-01-01

    After the 30-year post-closure maintenance period at hazardous waste landfills, long-term stability must be assured without continued intervention. Understanding water balance in the established vegetative cover system is central to predicting such stability. A Los Alamos National Laboratory research project has established a series of experimental cover treatment plots on a closed waste disposal site which will permit the determination of the effects of such critical parameters as soil cover design, leaf area index, and rooting characteristics on water balance under varied conditions. Data from these experiments are being analyzed by water balance modeling and other means. The results show consistent differences in soil moisture storage between soil profiles and between vegetation cover treatments

  1. Sequences Flanking the Gephyrin-Binding Site of GlyRβ Tune Receptor Stabilization at Synapses.

    Science.gov (United States)

    Grünewald, Nora; Jan, Audric; Salvatico, Charlotte; Kress, Vanessa; Renner, Marianne; Triller, Antoine; Specht, Christian G; Schwarz, Guenter

    2018-01-01

    The efficacy of synaptic transmission is determined by the number of neurotransmitter receptors at synapses. Their recruitment depends upon the availability of postsynaptic scaffolding molecules that interact with specific binding sequences of the receptor. At inhibitory synapses, gephyrin is the major scaffold protein that mediates the accumulation of heteromeric glycine receptors (GlyRs) via the cytoplasmic loop in the β-subunit (β-loop). This binding involves high- and low-affinity interactions, but the molecular mechanism of this bimodal binding and its implication in GlyR stabilization at synapses remain unknown. We have approached this question using a combination of quantitative biochemical tools and high-density single molecule tracking in cultured rat spinal cord neurons. The high-affinity binding site could be identified and was shown to rely on the formation of a 3 10 -helix C-terminal to the β-loop core gephyrin-binding motif. This site plays a structural role in shaping the core motif and represents the major contributor to the synaptic confinement of GlyRs by gephyrin. The N-terminal flanking sequence promotes lower affinity interactions by occupying newly identified binding sites on gephyrin. Despite its low affinity, this binding site plays a modulatory role in tuning the mobility of the receptor. Together, the GlyR β-loop sequences flanking the core-binding site differentially regulate the affinity of the receptor for gephyrin and its trapping at synapses. Our experimental approach thus bridges the gap between thermodynamic aspects of receptor-scaffold interactions and functional receptor stabilization at synapses in living cells.

  2. Catalytically active Au-O(OH)x- species stabilized by alkali ions on zeolites and mesoporous oxides

    Energy Technology Data Exchange (ETDEWEB)

    Yang, M.; Li, S.; Wang, Y.; Herron, J. A.; Xu, Y.; Allard, L. F.; Lee, S.; Huang, J.; Mavrikakis, M.; Flytzani-Stephanopoulos, M.

    2014-11-27

    We report that the addition of alkali ions (sodium or potassium) to gold on KLTL-zeolite and mesoporous MCM-41 silica stabilizes mononuclear gold in Au-O(OH)x-(Na or K) ensembles. This single-site gold species is active for the low-temperature (< 200°C) water-gas shift (WGS) reaction. Unexpectedly, gold is thus similar to platinum in creating –O and –OH linkages with more than eight alkali ions and establishing an active site on various supports. The intrinsic activity of the single-site gold species is the same on irreducible supports as on reducible ceria, iron oxide, and titania supports; apparently all sharing a common, similarly structured gold active site. This finding paves the way for using earth-abundant supports to disperse and stabilize precious metal atoms with alkali additives for the WGS and potentially other fuel processing reactions.

  3. Savannah River Site prioritization of transition activities

    International Nuclear Information System (INIS)

    Finley, R.H.

    1993-11-01

    Effective management of SRS conversion from primarily a production facility to other missions (or Decontamination and Decommissioning (D ampersand D)) requires a systematic and consistent method of prioritizing the transition activities. This report discusses the design of a prioritizing method developed to achieve systematic and consistent methods of prioritizing these activities

  4. Safety Oversight of Decommissioning Activities at DOE Nuclear Sites

    International Nuclear Information System (INIS)

    Zull, Lawrence M.; Yeniscavich, William

    2008-01-01

    The Defense Nuclear Facilities Safety Board (Board) is an independent federal agency established by Congress in 1988 to provide nuclear safety oversight of activities at U.S. Department of Energy (DOE) defense nuclear facilities. The activities under the Board's jurisdiction include the design, construction, startup, operation, and decommissioning of defense nuclear facilities at DOE sites. This paper reviews the Board's safety oversight of decommissioning activities at DOE sites, identifies the safety problems observed, and discusses Board initiatives to improve the safety of decommissioning activities at DOE sites. The decommissioning of former defense nuclear facilities has reduced the risk of radioactive material contamination and exposure to the public and site workers. In general, efforts to perform decommissioning work at DOE defense nuclear sites have been successful, and contractors performing decommissioning work have a good safety record. Decommissioning activities have recently been completed at sites identified for closure, including the Rocky Flats Environmental Technology Site, the Fernald Closure Project, and the Miamisburg Closure Project (the Mound site). The Rocky Flats and Fernald sites, which produced plutonium parts and uranium materials for defense needs (respectively), have been turned into wildlife refuges. The Mound site, which performed R and D activities on nuclear materials, has been converted into an industrial and technology park called the Mound Advanced Technology Center. The DOE Office of Legacy Management is responsible for the long term stewardship of these former EM sites. The Board has reviewed many decommissioning activities, and noted that there are valuable lessons learned that can benefit both DOE and the contractor. As part of its ongoing safety oversight responsibilities, the Board and its staff will continue to review the safety of DOE and contractor decommissioning activities at DOE defense nuclear sites

  5. Elliptically Bent X-Ray Mirrors with Active Temperature Stabilization

    International Nuclear Information System (INIS)

    Yuan, S.; Church, M.; Yashchuk, V.V.; Celestre, R.S.; McKinney, W.R.; Morrison, G.; Warwick, T.; Padmore, H.A.; Goldberg, K.A.; Kirschman, J.; Noll, T.

    2010-01-01

    We present details of design of elliptically bent Kirkpatrick-Baez mirrors developed and successfully used at the advanced light source for submicron focusing. A distinctive feature of the mirror design is an active temperature stabilization based on a Peltier element attached directly to the mirror body. The design and materials have been carefully optimized to provide high heat conductance between the mirror body and substrate. We describe the experimental procedures used when assembling and precisely shaping the mirrors, with special attention paid to laboratory testing of the mirror-temperature stabilization. For this purpose, the temperature dependence of the surface slope profile of a specially fabricated test mirror placed inside a temperature-controlled container was measured. We demonstrate that with active mirror-temperature stabilization, a change of the surrounding temperature by more than 3 K does not noticeably affect the mirror figure. Without temperature stabilization, the rms slope error is changed by approximately 1.5 μrad (primarily defocus) under the same conditions

  6. Personality predictors of longevity: Activity, Emotional Stability, and Conscientiousness

    Science.gov (United States)

    Terracciano, Antonio; Löckenhoff, Corinna E.; Zonderman, Alan B.; Ferrucci, Luigi; Costa, Paul T.

    2008-01-01

    Objective To examine the association between personality traits and longevity. Methods Using the Guilford-Zimmerman Temperament Survey, personality traits were assessed in 2359 participants (38% women; age: 17 to 98 years, M = 50) from the Baltimore Longitudinal Study of Aging (BLSA), starting in 1958. Over the duration of the study, 943 (40%) participants died, on average 18 years after their personality assessment. The association of each trait with longevity was examined by Cox regression controlling for demographic variables. Results In preliminary analyses among the deceased, those who scored one SD above the mean on General Activity (a facet of Extraversion), Emotional Stability (low Neuroticism), or Conscientiousness lived on average two to three years longer than those scoring one SD below the mean. Survival analyses on the full sample confirmed the association of General Activity, Emotional Stability, and Conscientiousness with lower risk of death, such that every one SD increase was related to about 13%, 15%, and 27% risk reduction, respectively. The association of personality traits with longevity was largely independent from the influence of smoking and obesity. Personality predictors of longevity did not differ by sex, except for Ascendance (a facet of Extraversion). Emotional Stability was a significant predictor when the analyses were limited to deaths due to cardiovascular disease, with comparable effect sizes for General Activity and Conscientiousness. Conclusions In a large sample of generally healthy individuals followed for almost five decades, longevity was associated with being conscientious, emotionally stable, and active. PMID:18596250

  7. Sludge stabilization at the Plutonium Finishing Plant, Hanford Site, Richland, Washington

    International Nuclear Information System (INIS)

    1994-10-01

    This Environmental Assessment evaluates the proposed action to operate two laboratory-size muffle furnaces in glovebox HC-21C, located in the Plutonium Finishing Plant (PFP), Hanford Site, Richland, Washington. The muffle furnaces would be used to stabilize chemically reactive sludges that contain approximately 25 kilograms (55 pounds) of plutonium by heating to approximately 500 to 1000 degrees C (900 to 1800 degrees F). The resulting stable powder, mostly plutonium oxide with impurities, would be stored in the PFP vaults. The presence of chemically reactive plutonium-bearing sludges in the process gloveboxes poses a risk to workers from radiation exposure and limits the availability of storage space for future plant cleanup. Therefore, there is a need to stabilize the material into a form suitable for long-term storage. This proposed action would be an interim action, which would take place prior to completion of an Environmental Impact Statement for the PFP which would evaluate stabilization of all plutonium-bearing materials and cleanout of the facility. However, only 10 percent of the total quantity of plutonium in reactive materials is in the sludges, so this action will not limit the choice of reasonable alternatives or prejudice the Record of Decision of the Plutonium Finishing Plant Environmental Impact Statement

  8. Robotics at Savannah River site: activity report

    International Nuclear Information System (INIS)

    Byrd, J.S.

    1984-09-01

    The objectives of the Robotics Technology Group at the Savannah River Laboratory are to employ modern industrial robots and to develop unique automation and robotic systems to enhance process operations at the Savannah River site (SRP and SRL). The incentives are to improve safety, reduce personnel radiation exposure, improve product quality and productivity, and to reduce operating costs. During the past year robotic systems have been installed to fill chemical dilution vials in a SRP laboratory at 772-F and remove radioactive waste materials in the SRL Californium Production Facility at 773-A. A robotic system to lubricate an extrusion press has been developed and demonstrated in the SRL robotics laboratory and is scheduled for installation at the 321-M fuel fabrication area. A mobile robot was employed by SRP for a radiation monitoring task at a waste tank top in H-Area. Several other robots are installed in the SRL robotics laboratories and application development programs are underway. The status of these applications is presented in this report

  9. Remedial action plan and site design for stabilization of the inactive uranium mill tailings sites at Rifle, Colorado: Final report

    International Nuclear Information System (INIS)

    1990-02-01

    This radiologic characterization of tho two inactive uranium millsites at Rifle, Colorado, was conducted by Bendix Field Engineering Corporation (Bendix) for the US Department of Energy (DOE), Grand Junction Projects Office, in accord with a Statement of Work prepared by the DOE Uranium Mill Tailings Remedial Action (UMTRA) Project Technical Assistance Contractor, Jacobs Engineering Group, Inc. (Jacobs). The purpose of this project is to define the extent of radioactive contamination at the Rifle sites that exceeds US Environmental Protection Agency, (EPA) standards for UMTRA sites. The data presented in this report are required for characterization of the areas adjacent to the tailings piles and for the subsequent design of cleanup activities. An orientation visit to the study area was conducted on 31 July--1 August 1984, in conjunction with Jacobs, to determine the approximate extent of contaminated area surrounding tho piles. During that visit, survey control points were located and baselines were defined from which survey grids would later be established; drilling requirements were assessed; and radiologic and geochemical data were collected for use in planning the radiologic fieldwork. The information gained from this visit was used by Jacobs, with cooperation by Bendix, to determine the scope of work required for the radiologic characterization of the Rifle sites. Fieldwork at Rifle was conducted from 1 October through 16 November 1984

  10. Remedial action plan and site design for stabilization of the inactive uranium mill tailings sites at Slick Rock, Colorado

    International Nuclear Information System (INIS)

    1993-07-01

    The Slick Rock uranium mill tailings sites are located near the small town of Slick Rock, in San Miguel County, Colorado. There are two designated UMTRA sites at Slick Rock, the Union Carbide (UC) site and the North Continent (NC) site. Both sites are adjacent to the Dolores River. The UC site is approximately 1 mile (mi) [2 kilometers (km)] downstream of the NC site. Contaminated materials cover an estimated 55 acres (ac) [22 hectares (ha)] at the UC site and 12 ac (4.9 ha) at the NC site. The sites contain former mill building concrete foundations, tailings piles, demolition debris, and areas contaminated by windblown and waterborne radioactive materials. The total estimated volume of contaminated materials is approximately 620, 000 cubic yards (yd 3 ) [470,000 cubic meters (m 3 )]. In addition to the contamination at the two processing site areas, four vicinity properties were contaminated. Contamination associated with the UC and NC sites has leached into groundwater

  11. Remedial action plan and site design for stabilization of the inactive uranium mill tailings site at Lowman, Idaho: Attachment 2, Geology report

    International Nuclear Information System (INIS)

    1991-09-01

    Detailed investigations of geologic, geomorphic, and seismic conditions at the Lowman site in central Idaho were conducted by the Technical Assistance Contractor. The purpose of these investigations was basic site characterization and the identification of potential geologic hazards that could affect long-term site stability. Subsequent engineering studies (e.g., analyses of the hydrologic regime and liquefaction potential) use this data . The geomorphic analysis is employed in the design of effective erosion protection. Studies of the regional and local seismotectonic setting, which included a detailed search for possible capable faults within a 65-km (40-mile) radius of the site, provided the basis for estimating seismic design parameters

  12. Lattice sites and stability of implanted Er in FZ and CZ Si

    CERN Document Server

    Wahl, U; Langouche, G; Vantomme, A

    1998-01-01

    We report on the lattice location of $^{167}$Er in Si measured by conversion electron emission channeling. In both FZ and CZ Si, a high fraction of Er (>65%) occupies near-tetrahedral interstitial (T) sites directly following 60 keV room temperature implantation at doses of 6 $\\times 10^{12}$ cm$^{-2}$. For higher doses, the as-implanted near-T fractions of Er visible by emission channeling are smaller, due to the beginning of amorphization. Following the recovery of implantation damage at 600°C, more than 70% of Er is found on near-T sites in both FZ and CZ Si. In FZ Si, Er exhibits a remarkable thermal stability and only prolonged annealing for several hours reduces the near-T fraction. On the other hand, annealing of CZ Si at 900°C for more than 10 minutes results in the majority of Er probes in sites of very low symmetry or disordered surroundings.

  13. Active site - a site of binding of affinity inhibitors in baker's yeast inorganic pyrophosphatase

    International Nuclear Information System (INIS)

    Svyato, I.E.; Sklyankina, V.A.; Avaeva, S.M.

    1986-01-01

    The interaction of the enzyme-substrate complex with methyl phosphate, O-phosphoethanolamine, O-phosphopropanolamine, N-acetylphosphoserine, and phosphoglyolic acid, as well as pyrophosphatase, modified by monoesters of phosphoric acid, with pyrophosphate and tripolyphosphate, was investigated. It was shown that the enzyme containing the substrate in the active site does not react with monophosphates, but modified pyrophosphatase entirely retains the ability to bind polyanions to the regulatory site. It is concluded that the inactivation of baker's yeast inorganic pyrophosphatase by monoesters of phosphoric acid, which are affinity inhibitors of it, is the result of modification of the active site of the enzyme

  14. Preparation and bactericide activity of gallic acid stabilized gold nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Moreno-Alvarez, S. A. [UASLP, Doctorado Institucional en Ingenieria y Ciencia de Materiales (Mexico); Martinez-Castanon, G. A., E-mail: mtzcastanon@fciencias.uaslp.m [UASLP, Maestria en Ciencias Odontologicas, Facultad de Estomatologia (Mexico); Nino-Martinez, N. [UASLP, Facultad de Ciencias (Mexico); Reyes-Macias, J. F.; Patino-Marin, N.; Loyola-Rodriguez, J. P. [UASLP, Maestria en Ciencias Odontologicas, Facultad de Estomatologia (Mexico); Ruiz, Facundo [UASLP, Facultad de Ciencias (Mexico)

    2010-10-15

    In this work, gold nanoparticles with three different sizes (13.7, 39.4, and 76.7 nm) were prepared using a simple aqueous method with gallic acid as the reducing and stabilizing agent, the different sizes were obtained varying some experimental parameters as the pH of the reaction and the amount of the gallic acid. The prepared nanoparticles were characterized using X-ray diffraction, transmission electron microscopy, dynamic light scattering, and UV-Vis spectroscopy. Samples were identified as elemental gold and present spherical morphology, a narrow size distribution and good stabilization according to TEM and DLS results. The antibacterial activity of this gallic acid stabilized gold nanoparticles against S. mutans (the etiologic agent of dental caries) was assessed using a microdilution method obtaining a minimum inhibitory concentration of 12.31, 12.31, and 49.25 {mu}g/mL for 13.7, 39.4, and 76.7 nm gold nanoparticles, respectively. The antibacterial assay showed that gold nanoparticles prepared in this work present a bactericide activity by a synergistic action with gallic acid. The MIC found for this nanoparticles are much lower than those reported for mixtures of gold nanoparticles and antibiotics.

  15. Preparation and bactericide activity of gallic acid stabilized gold nanoparticles

    International Nuclear Information System (INIS)

    Moreno-Alvarez, S. A.; Martinez-Castanon, G. A.; Nino-Martinez, N.; Reyes-Macias, J. F.; Patino-Marin, N.; Loyola-Rodriguez, J. P.; Ruiz, Facundo

    2010-01-01

    In this work, gold nanoparticles with three different sizes (13.7, 39.4, and 76.7 nm) were prepared using a simple aqueous method with gallic acid as the reducing and stabilizing agent, the different sizes were obtained varying some experimental parameters as the pH of the reaction and the amount of the gallic acid. The prepared nanoparticles were characterized using X-ray diffraction, transmission electron microscopy, dynamic light scattering, and UV-Vis spectroscopy. Samples were identified as elemental gold and present spherical morphology, a narrow size distribution and good stabilization according to TEM and DLS results. The antibacterial activity of this gallic acid stabilized gold nanoparticles against S. mutans (the etiologic agent of dental caries) was assessed using a microdilution method obtaining a minimum inhibitory concentration of 12.31, 12.31, and 49.25 μg/mL for 13.7, 39.4, and 76.7 nm gold nanoparticles, respectively. The antibacterial assay showed that gold nanoparticles prepared in this work present a bactericide activity by a synergistic action with gallic acid. The MIC found for this nanoparticles are much lower than those reported for mixtures of gold nanoparticles and antibiotics.

  16. Resolving the Structure of Active Sites on Platinum Catalytic Nanoparticles

    DEFF Research Database (Denmark)

    Chang, Lan Yun; Barnard, Amanda S.; Gontard, Lionel Cervera

    2010-01-01

    Accurate understanding of the structure of active sites is fundamentally important in predicting catalytic properties of heterogeneous nanocatalysts. We present an accurate determination of both experimental and theoretical atomic structures of surface monatomic steps on industrial platinum nanop...

  17. Activity and Stability of Nanoscale Oxygen Reduction Catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Shao-Horn, Yang

    2015-07-28

    Design of highly active and stable nanoscale catalysts for electro-oxidation of small organic molecules is of great importance to the development of efficient fuel cells. The amount and instability of Pt-based catalysts in the cathode limits the cost, efficiency and lifetime of proton exchange membrane fuel cells. We developed a microscopic understanding of the factors governing activity and stability in Pt and PtM alloys. Experimental efforts were focused on probing the size and shape dependence of ORR activity of Pt-based nanoparticles supported on carbon nanotubes. A microscopic understanding of the activity was achieved by correlating voltammetry and rotating ring disk electrodes to surface atomic and electronic structures, which were elucidated predominantly by high-resolution transmission electron microscopy (HRTEM), Scanning transmission electron microscopy energy dispersive X-ray Spectroscopy (STEM-EDS) and synchrotron X-ray absorption spectroscopy (XAS).

  18. Design and creation of a Ca2+ binding site in human lysozyme to enhance structural stability.

    OpenAIRE

    Kuroki, R; Taniyama, Y; Seko, C; Nakamura, H; Kikuchi, M; Ikehara, M

    1989-01-01

    A Ca2+ binding site like an EF-hand motif was designed and created in human lysozyme by replacing both Gln-86 and Ala-92 with aspartic acids by site-directed mutagenesis. The mutant human lysozyme (D86/92-lysozyme) was expressed and secreted by yeast. One Ca2+ was found to bind one molecule of the purified protein with the binding constant 5.0 x 10(6) M-1. The enzymatic activity of holo-D86/92-lysozyme against glycol chitin at 40 degrees C was 2-fold higher than that of the native lysozyme. M...

  19. Loss of Consciousness Is Associated with Stabilization of Cortical Activity.

    Science.gov (United States)

    Solovey, Guillermo; Alonso, Leandro M; Yanagawa, Toru; Fujii, Naotaka; Magnasco, Marcelo O; Cecchi, Guillermo A; Proekt, Alex

    2015-07-29

    What aspects of neuronal activity distinguish the conscious from the unconscious brain? This has been a subject of intense interest and debate since the early days of neurophysiology. However, as any practicing anesthesiologist can attest, it is currently not possible to reliably distinguish a conscious state from an unconscious one on the basis of brain activity. Here we approach this problem from the perspective of dynamical systems theory. We argue that the brain, as a dynamical system, is self-regulated at the boundary between stable and unstable regimes, allowing it in particular to maintain high susceptibility to stimuli. To test this hypothesis, we performed stability analysis of high-density electrocorticography recordings covering an entire cerebral hemisphere in monkeys during reversible loss of consciousness. We show that, during loss of consciousness, the number of eigenmodes at the edge of instability decreases smoothly, independently of the type of anesthetic and specific features of brain activity. The eigenmodes drift back toward the unstable line during recovery of consciousness. Furthermore, we show that stability is an emergent phenomenon dependent on the correlations among activity in different cortical regions rather than signals taken in isolation. These findings support the conclusion that dynamics at the edge of instability are essential for maintaining consciousness and provide a novel and principled measure that distinguishes between the conscious and the unconscious brain. What distinguishes brain activity during consciousness from that observed during unconsciousness? Answering this question has proven difficult because neither consciousness nor lack thereof have universal signatures in terms of most specific features of brain activity. For instance, different anesthetics induce different patterns of brain activity. We demonstrate that loss of consciousness is universally and reliably associated with stabilization of cortical dynamics

  20. Phase stability and site preference of Sm(Fe,T)12

    International Nuclear Information System (INIS)

    Chen Nanxian; Hao Shiqiang; Wu Yu; Shen Jiang

    2001-01-01

    The structure of intermetallics Sm(Fe,T) 12 is analyzed via a quasi-ab initio pair potentials PHI Fe-Fe (r), PHI Sm-Fe (r), PHI Sm-Sm (r), PHI Sm-T (r), PHI Fe-T (r) and PHI T-T (r). The calculation results show that each of Cr, V, Mo and Ti significantly decreases the cohesive energy of Sm(Fe,T) 12 , and thus stabilizes its structure of ThMn 12 . The calculated lattice constants coincide quite well with experimental values. The sequence of site preference occupation is 8i, 8j and 8f, with the 8i occupation corresponding to the greatest energy decrease. The calculated results also show that each of Co, Cu, Ni and Sc does not stabilize the system with the structure of ThMn 12 . The calculated crystal structure can recover after either an overall wide-range macro-deformation or atomic random motion, demonstrating that an Sm-Fe-T system has the stable structure of ThMn 12 . The crystal space group remaining consistent at different temperatures is also shown in this paper. All of the results verify that the first principle potentials based on the lattice inversion technique are effective

  1. Klipperaas study site. Scope of activities and main results

    International Nuclear Information System (INIS)

    Ahlbom, K.; Andersson, J.E.; Andersson, Peter; Ittner, T.; Tiren, S.; Ljunggren, C.

    1992-09-01

    During the period from 1977 - 1986 SKB (Swedish Nuclear Fuel and Waste Management Co.) performed surface and borehole investigations of 14 study sites for the purpose of assessing their suitability for a repository of spent nuclear fuel. The next phase in the SKB site selection rpogramme will be to perform detailed characterisation, including characterization from shafts and/or tunnels, of two or three sites. The detailed investigations will continue over several years to provide all the data needed for a licensing application to build a repository. Such an application is foreseen to be given to the authorities around the year 2003. It is presently not clear if any of the study sites will be selected as a site for detailed characterization. Other sites with geological and/or socio-economical characteristics judged more favorable may very well be the ones selected. However, as a part of the background documentation needed for the site selection studies to come, summary reports will be prepared for most study sites. These reports will include scope of activities, main results, uncertainties and need of complementary investigations. This report concern the Klipperaas study site. The main topics are the scope of activities, geologic model, geohydrological model, groundwater chemistry, assessment of solute transport, and rock mechanics

  2. Peptide fibrils with altered stability, activity, and cell selectivity.

    Science.gov (United States)

    Chen, Long; Liang, Jun F

    2013-07-08

    Peptides have some unique and superior features compared to proteins. However, the use of peptides as therapeutics is hampered by their low stability and cell selectivity. In this study, a new lytic peptide (CL-1, FLGALFRALSRLL) was constructed. Under the physiological condition, peptide CL-1 self-assembled into dynamically stable aggregates with fibrils-like structures. Aggregated CL-1 demonstrated dramatically altered activity and stability in comparison with single molecule CL-1 and other lytic peptides: when incubated with cocultured bacteria and tissue cells, CL-1 aggregates killed bacteria selectively but spared cocultured human cells; CL-1 aggregates were kept intact in human serum for more than five hours. Peptide-cell interaction studies performed on lipid monolayers and live human tissue cells revealed that in comparison with monomeric CL-1, aggregated CL-1 had decreased cell affinity and membrane insertion capability on tissue cells. A dynamic process involving aggregate dissociation and rearrangement seemed to be an essential step for membrane bound CL-1 aggregates to realize its cytotoxicity to tissue cells. Our study suggests that peptide aggregation could be as important as the charge and secondary structure of a peptide in affecting peptide-cell interactions. Controlling peptide self-assembly represents a new way to increase the stability and cell selectivity of bioactive peptides for wide biomedical applications.

  3. Evaluation of pancreatin stability through enzyme activity determination

    Directory of Open Access Journals (Sweden)

    Terra Gleysson De Paula

    2016-09-01

    Full Text Available Pancreatin is a biotechnological product containing an enzyme complex, obtained from porcine pancreas, that is employed in treating pancreatic diseases. Experiments regarding the stability of the pharmaceutical formulation containing pancreatin were performed using standard binary mixtures with 6 excipients in a 1:1 ratio (m/m and a commercial formulation. To accomplish these goals, samples were stored for 1, 3 and 6 months at 40 ± 1 °C and 75 ± 5 % relative humidity (RH and 40 ± 1 °C and 0 % RH. Stress testing was also performed. All samples were analyzed to evaluate the α-amylase, lipase and protease activities through UV/Vis spectrophotometry. The results revealed that the excipient proprieties and the storage conditions affected enzyme stability. Humidity was a strong influencing factor in the reduction of α-amylase and protease activities. Stress testing indicated that pH 9.0 and UV light did not induce substantial alterations in enzyme activity.

  4. Attachment Site Cysteine Thiol pKa Is a Key Driver for Site-Dependent Stability of THIOMAB Antibody-Drug Conjugates.

    Science.gov (United States)

    Vollmar, Breanna S; Wei, Binqing; Ohri, Rachana; Zhou, Jianhui; He, Jintang; Yu, Shang-Fan; Leipold, Douglas; Cosino, Ely; Yee, Sharon; Fourie-O'Donohue, Aimee; Li, Guangmin; Phillips, Gail L; Kozak, Katherine R; Kamath, Amrita; Xu, Keyang; Lee, Genee; Lazar, Greg A; Erickson, Hans K

    2017-10-18

    The incorporation of cysteines into antibodies by mutagenesis allows for the direct conjugation of small molecules to specific sites on the antibody via disulfide bonds. The stability of the disulfide bond linkage between the small molecule and the antibody is highly dependent on the location of the engineered cysteine in either the heavy chain (HC) or the light chain (LC) of the antibody. Here, we explore the basis for this site-dependent stability. We evaluated the in vivo efficacy and pharmacokinetics of five different cysteine mutants of trastuzumab conjugated to a pyrrolobenzodiazepine (PBD) via disulfide bonds. A significant correlation was observed between disulfide stability and efficacy for the conjugates. We hypothesized that the observed site-dependent stability of the disulfide-linked conjugates could be due to differences in the attachment site cysteine thiol pK a . We measured the cysteine thiol pK a using isothermal titration calorimetry (ITC) and found that the variants with the highest thiol pK a (LC K149C and HC A140C) were found to yield the conjugates with the greatest in vivo stability. Guided by homology modeling, we identified several mutations adjacent to LC K149C that reduced the cysteine thiol pK a and, thus, decreased the in vivo stability of the disulfide-linked PBD conjugated to LC K149C. We also present results suggesting that the high thiol pK a of LC K149C is responsible for the sustained circulation stability of LC K149C TDCs utilizing a maleimide-based linker. Taken together, our results provide evidence that the site-dependent stability of cys-engineered antibody-drug conjugates may be explained by interactions between the engineered cysteine and the local protein environment that serves to modulate the side-chain thiol pK a . The influence of cysteine thiol pK a on stability and efficacy offers a new parameter for the optimization of ADCs that utilize cysteine engineering.

  5. Field application of innovative grouting agents for in situ stabilization of buried waste sites

    International Nuclear Information System (INIS)

    Loomis, G.G.; Farnsworth, R.K.

    1997-01-01

    This paper presents field applications for two innovative grouting agents that were used to in situ stabilize buried waste sites, via jet grouting. The two grouting agents include paraffin and a proprietary iron oxide based cement grout called TECT. These materials were tested in specially designed cold test pits that simulate buried transuranic waste at the Idaho National Engineering Laboratory (INEL). The field demonstrations were performed at the INEL in an area referred to as the Cold Test Pit, which is adjacent to the INEL Radioactive Waste Management Complex (RWMC). At the RWMC, 56,000 m 3 of transuranic (TRU) waste is co-mingled with over 170,000 m 3 of soil in shallow land burial. Improving the confinement of this waste is one of the options for final disposition of this waste. Using jet-grouting technology to inject these materials into the pore spaces of buried waste sites results in the creation of buried monolithic waste forms that simultaneously protect the waste from subsidence, while eliminating the migratory potential of hazardous and radioactive contaminants in the waste

  6. Actively-stabilized photomultiplier tube base for vacuum operation

    International Nuclear Information System (INIS)

    Bryan, M.A; Morris, C.L.; Idzorek, G.C.

    1992-01-01

    An actively stabilized photomultiplier tube (PMT) base design for an Amperex XP-2262B PMT is described. Positive-negative-positive transistors are used as low-impedance current sources to maintain constant voltages on the last three dynodes. This technique results in a highly stable, low-power tube base ideal for use with low-duty-factor beams, such as those found at the Clinton P. Anderson Meson Physics Facility. Furthermore, because of the low power usage of this large design, these bases can be sealed in a heat-conductive, electrically insulating material and used in a vacuum

  7. Dashboard applications to monitor experiment activities at sites

    International Nuclear Information System (INIS)

    Andreeva, Julia; Gaidioz, Benjamin; Grigoras, Costin; Kokoszkiewicz, Lukasz; Lanciotti, Elisa; Rocha, Ricardo; Saiz, Pablo; Santinelli, Roberto; Sidorova, Irina; Sciaba, Andrea; Belforte, Stefano; Boehm, Max; Casajus, Adrian; Flix, Josep; Tsaregorodtsev, Andrei

    2010-01-01

    In the framework of a distributed computing environment, such as WLCG, monitoring has a key role in order to keep under control activities going on in sites located in different countries and involving people based in many different sites. To be able to cope with such a large scale heterogeneous infrastructure, it is necessary to have monitoring tools providing a complete and reliable view of the overall performance of the sites. Moreover, the structure of a monitoring system critically depends on the object to monitor and on the users it is addressed to. In this article we will describe two different monitoring systems both aimed to monitor activities and services provided in the WLCG framework, but designed in order to meet the requirements of different users: Site Status Board has an overall view of the services available in all the sites supporting an experiment, whereas Siteview provides a complete view of all the activities going on at a site, for all the experiments supported by the site.

  8. Active sites environmental monitoring program FY 1997 annual report

    International Nuclear Information System (INIS)

    Morrissey, C.M.; Marshall, D.S.; Cunningham, G.R.

    1998-03-01

    This report summarizes the activities conducted by the Active Sites Environmental Monitoring Program (ASEMP) from October 1996 through September 1997. The purpose of the program is to provide early detection and performance monitoring at active low-level waste (LLW) disposal sites in Solid Waste Storage Area (SWSA) 6 and transuranic (TRU) waste storage sites in SWSA 5 North. This report continues a series of annual and semiannual reports that present the results of ASEMP monitoring activities. This report details monitoring results for fiscal year (FY) 1997 from SWSA 6, including the Interim Waste Management Facility (IWMF) and the Hillcut Disposal Test Facility (HDTF), and (2) TRU-waste storage areas in SWSA 5 N. This report presents a summary of the methodology used to gather data for each major area along with the FY 1997 results. Figures referenced in the text are found in Appendix A and data tables are presented in Appendix B

  9. Prolonged stability of antimicrobial activity in peritoneal dialysis solutions.

    Science.gov (United States)

    Dooley, David P; Tyler, J Robert; Wortham, William G; Harrison, Linda S; Starnes, William F; Collins, George R; Ozuna, Irene S; Violet, Patty L; Ward, John A

    2003-01-01

    To evaluate the stability of the antimicrobial chemical and bioactivity of gentamicin, vancomycin, and gentamicin and vancomycin in combination, and the stability of the bioactivity of ceftazidime, admixed in standard peritoneal dialysis solutions and then maintained over a 14-day period at room temperature or under refrigeration. Peritoneal dialysis center and microbiology laboratory at a military, teaching medical center. Standard peritoneal dialysate bags admixed with gentamicin, vancomycin, gentamicin and vancomycin in combination, or ceftazidime were stored at either 4 degrees C or 20 degrees C for 14 days. Sequential aliquots were withdrawn and assayed for antibiotic activity by bioassay and, except for ceftazidime, immunoassay for chemical activity. The bioassay was performed using a standardized Kirby-Bauer disc method. Significance was determined by ANOVA and, where the effect size was significant at the p < 0.05 level, the application of the paired t-test or the Wilcoxon signed rank test to the difference in activity between the first and last samples. Antibiotic concentration by immunoassay did not significantly deteriorate over 14 days for vancomycin or gentamicin when either room temperature or refrigerated samples were studied. By bioassay, gentamicin and ceftazidime, but not vancomycin, lost moderate but significant activity over 14 days when refrigerated bags were assayed (except for an insignificant decrement in gentamicin in the combined vancomycin and gentamicin bags). Bags stored at room temperature, in general, lost significant bioactivity over 14 days, but to levels where clinical efficacy would still be expected. The vancomycin bioassay performed on the combination bags demonstrated a remarkably enhanced bioactivity, presumably reflecting synergy with gentamicin. These data indicate that the study antibiotics admixed with peritoneal dialysis fluids retain stable chemical activity, whether refrigerated or kept at room temperature, for at least

  10. The Effects of Active Straight Leg Raising on Tonicity and Activity of Pelvic Stabilizer Muscles

    Directory of Open Access Journals (Sweden)

    Azadeh Shadmehr

    2011-01-01

    Full Text Available Objective: Active straight leg raising (SLR test is advocated as a valid diagnostic method in diagnosis of sacroiliac joint (SIJ dysfunction that can assess the quality of load transfer between trunk and lower limb. The aim of this study is Comparison of changes in tonicity and activity of pelvic stabilizer muscles during active SLR, between healthy individuals and patients with sacroiliac joint pain. Materials & Methods: A case – control study was designed in 26 women (19-50 years old. With use of simple sampling, surface electromyography from rectus abdominis, external oblique, internal oblique, adductor longus, erector spine, gluteus maximus and biceps femoris was recorded in 26 subjects (15 healthy females and 11 females with sacroiliac pain in resting position and during active SLR test. Resting muscle tonicity and rms during ramp time and hold time in active SLR test were assessed by non parametric-two independent sample test. Results: Biceps femoris activity in resting position was significantly larger in patients group (P<0.05. During the active SLR, the women with sacroiliac joint pain used much less activity in some pelvic stabilizer muscles compared to the healthy subjects (P<0.05. Conclusion: The increased resting tonicity of biceps femoris and decreased activity of pelvic stabilizer muscles in subjects with sacroiliac joint pain, suggests an alteration in the strategy for lumbopelvic stabilization that may disrupt load transference through the pelvis.

  11. Substrate Shuttling Between Active Sites of Uroporphyrinogen Decarboxylase in Not Required to Generate Coproporphyrinogen

    Energy Technology Data Exchange (ETDEWEB)

    Phillips, J.; Warby, C; Whitby, F; Kushner, J; Hill, C

    2009-01-01

    Uroporphyrinogen decarboxylase (URO-D; EC 4.1.1.37), the fifth enzyme of the heme biosynthetic pathway, is required for the production of heme, vitamin B12, siroheme, and chlorophyll precursors. URO-D catalyzes the sequential decarboxylation of four acetate side chains in the pyrrole groups of uroporphyrinogen to produce coproporphyrinogen. URO-D is a stable homodimer, with the active-site clefts of the two subunits adjacent to each other. It has been hypothesized that the two catalytic centers interact functionally, perhaps by shuttling of reaction intermediates between subunits. We tested this hypothesis by construction of a single-chain protein (single-chain URO-D) in which the two subunits were connected by a flexible linker. The crystal structure of this protein was shown to be superimposable with wild-type activity and to have comparable catalytic activity. Mutations that impaired one or the other of the two active sites of single-chain URO-D resulted in approximately half of wild-type activity. The distributions of reaction intermediates were the same for mutant and wild-type sequences and were unaltered in a competition experiment using I and III isomer substrates. These observations indicate that communication between active sites is not required for enzyme function and suggest that the dimeric structure of URO-D is required to achieve conformational stability and to create a large active-site cleft.

  12. Redox modulation of curcumin stability: Redox active antioxidants increase chemical stability of curcumin.

    Science.gov (United States)

    Nimiya, Yoshiki; Wang, Weicang; Du, Zheyuan; Sukamtoh, Elvira; Zhu, Julia; Decker, Eric; Zhang, Guodong

    2016-03-01

    Substantial studies have shown that curcumin, a dietary compound from turmeric, has beneficial effects on many diseases. However, curcumin rapidly degrades at physiological pH, making it difficult to interpret whether the observed actions of curcumin are from curcumin itself or its degradation products. Therefore, it is important to better understand the mechanisms involved in curcumin degradation and the roles of degradation in its biological actions. Here, we show that a series of redox active antioxidants with diverse chemical structures, including gallic acid, ascorbate (vitamin C), tert-butylhydroquinone (TBHQ), caffeic acid, rosmarinic acid, and Trolox (a water-soluble analog of vitamin E), dramatically increased curcumin stability in phosphate buffer at physiological pH. When treated in basal cell culture medium in MC38 colon cancer cells, curcumin rapidly degraded with a half-life of several minutes and showed a weak antiproliferative effect; co-addition of antioxidants enhanced stability and antiproliferative effect of curcumin. Finally, co-administration of antioxidant significantly increased plasma level of curcumin in animal models. Together, these studies strongly suggest that a redox-dependent mechanism plays a critical role in mediating curcumin degradation. In addition, curcumin itself, instead of its degradation products, is largely responsible for the observed biological actions of curcumin. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  13. Comparison of long-term stability of containment systems for residues and wastes contaminated with naturally occurring radionuclides at an arid site and two humid sites

    International Nuclear Information System (INIS)

    Winters, M.; Merry-Libby, P.; Hinchman, R.

    1985-01-01

    The long-term stability of near-surface containment systems designed for the management of radioactive wastes and residues contaminated with naturally occurring radionuclides are compared at the three different sites. The containment designs are: (1) a diked 8.9-m high mound, including a 3.2-m layered cap at a site (humid) near Lewiston, New York, (2) a 6.8-m-high mound, including a similar 3.2-m cap at a site (humid) near Oak Ridge, Tennessee, and (3) 4.8-m deep trenches with 3.0-m backfilled caps at a site (arid) near Hanford, Washington. Geological, hydrological, and biological factors affecting the long-term (1000-year) integrity of the containment systems at each site are examined, including: erosion, flooding, drought, wildfire, slope and cover failure, plant root penetration, burrowing animals, other soil-forming processes, and land-use changes. For the containment designs evaluated, releases of radon-222 at the arid site are predicted to be several orders of magnitude higher than at the two humid sites - upon initial burial and at 1000 years (after severe erosion). Transfer of wastes containing naturally occurring radionuclides from a humid to an arid environment offers little or no advantage relative to long-term stability of the containment system and has a definite disadvantage in terms of gaseous radioactive releases. 26 references, 3 figures, 4 tables

  14. Probing the putative active site of YjdL

    DEFF Research Database (Denmark)

    Jensen, Johanne Mørch; Ismat, Fouzia; Szakonyi, Gerda

    2012-01-01

    pocket that opens towards the extracellular space. The C-terminal side chain faces in the opposite direction into a sub pocket that faces the cytoplasm. These data indicated a stabilizing effect on a bulky N-terminal residue by an Ala281Phe variant and on the dipeptide backbone by Trp278...... with Glu388, a preliminary orientation model of a dipeptide in the YjdL cavity is presented. Single site mutations of particularly Ala281 and Trp278 support the presented orientation. A dipeptide bound in the cavity of YjdL appears to be oriented such that the N-terminal side chain protrudes into a sub...

  15. Passive and Active Stabilization of Liquid Bridges in Low Gravity

    Science.gov (United States)

    Marston, Philip L.; Thiessen, David B.; Marr-Lyon, Mark J.; Wei, Wei; Niederhaus, Charles E.; Truong, Duc K.

    2001-01-01

    Tests are planned in the low gravity environment of the International Space Station (ISS) of new methods for the suppression of the capillary instability of liquid bridges. Our suppression methods are unusual in that they are not limited to liquid bridges having very special properties and may impact a variety of low-gravity and earth-based technologies. There are two main approaches to be investigated: (1) Passive Acoustic Stabilization (PAS); and (2) Active Electrostatic Stabilization (AES). In PAS, the suppression of the mode growth is accomplished by placing the bridge in an acoustic field having the appropriate properties such that the acoustic radiation pressure automatically pulls outward on the thinnest portion of the bridge. In AES, the bridge deformation is sensed optically and counteracted by actively adjusting the electrostatic Maxwell stresses via two ring electrodes concentric with the slightly conducting bridge to offset the growth of the unstable mode. While the present work emphasizes cylindrical bridges, the methods need not be restricted to that case. The methods to be explored are relevant to the suppression of capillary instabilities in floating zone crystal growth, breakup of liquid jets and columns, bubbles, and annular films as well as the management of coolants or propellants in low-gravity.

  16. Modification of polymer surfaces to enhance enzyme activity and stability

    DEFF Research Database (Denmark)

    Hoffmann, Christian

    Enzyme immobilization is an important concept for the development of improved biocatalytic processes, primarily through facilitated separation procedures. However, enzyme immobilization usually comes at a price of reduced biocatalytic activity. For this reason, different immobilization methods have...... already been developed, combining the same goal to improve enzyme activity, stability and selectivity. Polymer materials have shown, due to their easy processibility and versatile properties, high potential as enzyme support. However, in order to achieve improved enzyme performance, the combination...... of different factors, such as the nature of the enzyme, the properties of the support, the type of immobilization and the interaction between enzyme and support, has to be taken into consideration. In this thesis, these factors are pursued and addressed by exploiting various types of polymers with focus...

  17. Enhanced biological activity of carotenoids stabilized by phenyl groups.

    Science.gov (United States)

    You, Ji Suk; Jeon, Sunhwa; Byun, Youn Jung; Koo, Sangho; Choi, Shin Sik

    2015-06-15

    Carotenoids are lipid soluble food ingredients with multifunction including antioxidant and anticancer activities. However, carotenoids are destructively oxidized upon reaction with radicals resulting in toxic effects on biological systems. Two synthetic carotenoids (BAS and BTS) containing the aromatic phenyl groups with a para-substituent (OMe and Me, respectively) at C-13 and C-13' position were prepared in order to overcome a structural instability of carotenoid. Both BAS and BTS exerted stronger radical scavenging activity than β-carotene in DPPH and ABTS assays. In particular, BTS significantly reduced in vivo ROS (reactive oxygen species) levels and improved body growth and reproduction of Caenorhabditiselegans. BTS has a great potential for the advanced and modified carotenoid material with stability leading to enhanced bioavailability. Copyright © 2015 Elsevier Ltd. All rights reserved.

  18. Theory, Investigation and Stability of Cathode Electrocatalytic Activity

    Energy Technology Data Exchange (ETDEWEB)

    Ding, Dong; Liu, Mingfei; Lai, Samson; Blinn, Kevin; Liu, Meilin

    2012-09-30

    The main objective of this project is to systematically characterize the surface composition, morphology, and electro-catalytic properties of catalysts coated on LSCF, aiming to establish the scientific basis for rational design of high-performance cathodes by combining a porous backbone (such as LSCF) with a thin catalyst coating. The understanding gained will help us to optimize the composition and morphology of the catalyst layer and microstructure of the LSCF backbone for better performance. More specifically, the technical objectives include: (1) to characterize the surface composition, morphology, and electro-catalytic properties of catalysts coated on LSCF; (2) to characterize the microscopic details and stability of the LSCF-catalyst (e.g., LSM) interfaces; (3) to establish the scientific basis for rational design of high-performance cathodes by combining a porous backbone (such as LSCF) with a thin catalyst coating; and (4) to demonstrate that the performance and stability of porous LSCF cathodes can be enhanced by the application of a thin-film coating of LSM through a solution infiltration process in small homemade button cells and in commercially available cells of larger dimension. We have successfully developed dense, conformal LSM films with desired structure, composition, morphology, and thickness on the LSCF surfaces by two different infiltration processes: a non-aqueous and a water-based sol-gel process. It is demonstrated that the activity and stability of LSCF cathodes can be improved by the introduction of a thin-film LSM coating through an infiltration process. Surface and interface of the LSM-coated LSCF cathode were systematically characterized using advanced microscopy and spectroscopy techniques. TEM observation suggests that a layer of La and Sr oxide was formed on LSCF surfaces after annealing. With LSM infiltration, in contrast, we no longer observe such La/Sr oxide layer on the LSM-coated LSCF samples after annealing under similar

  19. Activity and Stability of Biofilm Uricase of Lactobacillus plantarum for Uric Acid Biosensor

    Science.gov (United States)

    Iswantini, Dyah; Rachmatia, Rescy; Diana, Novita Rose; Nurhidayat, Novik; Akhiruddin; Saprudin, Deden

    2016-01-01

    Research of uric acid biosensor used a Lactobacillus plantarum was successfully conducted. Lactobacillus plantarum could produce uricase that could be used as uric acid biosensor. Therefore, lifetime of bacteria were quite short that caused the bacteria could not detect uric acid for a long time. To avoid this problem, development of biofilm for uric acid biosensor is important. Biofilms is a structured community of bacterial cells, stick together and are able to maintain a bacteria in an extreme environments. The purpose of present study was to determine and compare the activity of uricase produced by L. plantarum, deposited whithin biofilm and planktonic bacteria on glassy carbon electrode (GCEb & GCE), also to determine the stability of biofilm. The optimization process was conducted by using temperature, pH, and substrate concentration as the parameters. It showed that the activity of uricase within biofilm was able to increase the oxidation current. GCEb and GCE yielded the oxidation current in the amount of 47.24 μA and 23.04 μA, respectively, under the same condition. Results indicated that the optimum condition for uric acid biosensor using biofilm were pH 10, temperature of 40 oC, and uric acid concentration of 5 mM. The stability of GCEb decreased after 10 hours used, with decreasing percentage over 86.33%. This low stability probably caused by the unprotected active site of the enzyme that the enzyme is easier to experience the denaturation.

  20. Remedial action plan and site design for stabilization of the inactive uranium mill tailings sites at Rifle, Colorado

    Energy Technology Data Exchange (ETDEWEB)

    1992-02-01

    This appendix assesses the present conditions and data gathered about the two inactive uranium mill tailings sites near Rifle, Colorado, and the designated disposal site six miles north of Rifle in the area of Estes Gulch. It consolidates available engineering, radiological, geotechnical, hydrological, meteorological, and other information pertinent to the design of the Remedial Action Plan (RAP). The data characterize conditions at the mill, tailings, and disposal site so that the Remedial Action Contractor (RAC) may complete final designs for the remedial actions.

  1. Active chemisorption sites in functionalized ionic liquids for carbon capture.

    Science.gov (United States)

    Cui, Guokai; Wang, Jianji; Zhang, Suojiang

    2016-07-25

    Development of novel technologies for the efficient and reversible capture of CO2 is highly desired. In the last decade, CO2 capture using ionic liquids has attracted intensive attention from both academia and industry, and has been recognized as a very promising technology. Recently, a new approach has been developed for highly efficient capture of CO2 by site-containing ionic liquids through chemical interaction. This perspective review focuses on the recent advances in the chemical absorption of CO2 using site-containing ionic liquids, such as amino-based ionic liquids, azolate ionic liquids, phenolate ionic liquids, dual-functionalized ionic liquids, pyridine-containing ionic liquids and so on. Other site-containing liquid absorbents such as amine-based solutions, switchable solvents, and functionalized ionic liquid-amine blends are also investigated. Strategies have been discussed for how to activate the existent reactive sites and develop novel reactive sites by physical and chemical methods to enhance CO2 absorption capacity and reduce absorption enthalpy. The carbon capture mechanisms of these site-containing liquid absorbents are also presented. Particular attention has been paid to the latest progress in CO2 capture in multiple-site interactions by amino-free anion-functionalized ionic liquids. In the last section, future directions and prospects for carbon capture by site-containing ionic liquids are outlined.

  2. Remedial action plan and site design for stabilization of the inactive uranium mill tailings site at Lowman, Idaho: Remedial action selection report for the Lowman UMTRA project site, Idaho

    International Nuclear Information System (INIS)

    Matthews, M.L.; Nagel, J.

    1991-09-01

    The inactive uranium mill tailings site near Lowman, Idaho, was designated as one of 24 abandoned uranium tailings sites to be remediated by the US Department of Energy (DOE) under the Uranium Mill Tailings Radiation Control Act of 1978 (UMTRCA). The UMTRCA requires that the US Nuclear Regulatory Commission (NRC) concur with the DOE's remedial action plan and certify that the remedial action complies with the standards promulgated by the US Environmental Protection Agency (EPA). The remedial action plan (RAP), which includes this remedial action selection report (RAS), has been developed to serve a two-fold purpose. First, it describes the activities that are proposed by the DOE to accomplish long-term stabilization and control of residual radioactive materials at the inactive uranium processing site near Lowman, Idaho. Second, this document and the remainder of the RAP, upon concurrence and execution by the DOE, the State of Idaho, and the NRC, becomes Appendix B of the Cooperative Agreement (No. DE-FC04-85AL20535) between the DOE and the State of Idaho

  3. Stability-activity tradeoffs constrain the adaptive evolution of RubisCO.

    Science.gov (United States)

    Studer, Romain A; Christin, Pascal-Antoine; Williams, Mark A; Orengo, Christine A

    2014-02-11

    A well-known case of evolutionary adaptation is that of ribulose-1,5-bisphosphate carboxylase (RubisCO), the enzyme responsible for fixation of CO2 during photosynthesis. Although the majority of plants use the ancestral C3 photosynthetic pathway, many flowering plants have evolved a derived pathway named C4 photosynthesis. The latter concentrates CO2, and C4 RubisCOs consequently have lower specificity for, and faster turnover of, CO2. The C4 forms result from convergent evolution in multiple clades, with substitutions at a small number of sites under positive selection. To understand the physical constraints on these evolutionary changes, we reconstructed in silico ancestral sequences and 3D structures of RubisCO from a large group of related C3 and C4 species. We were able to precisely track their past evolutionary trajectories, identify mutations on each branch of the phylogeny, and evaluate their stability effect. We show that RubisCO evolution has been constrained by stability-activity tradeoffs similar in character to those previously identified in laboratory-based experiments. The C4 properties require a subset of several ancestral destabilizing mutations, which from their location in the structure are inferred to mainly be involved in enhancing conformational flexibility of the open-closed transition in the catalytic cycle. These mutations are near, but not in, the active site or at intersubunit interfaces. The C3 to C4 transition is preceded by a sustained period in which stability of the enzyme is increased, creating the capacity to accept the functionally necessary destabilizing mutations, and is immediately followed by compensatory mutations that restore global stability.

  4. Active Sites Environmental Monitoring Program: Mid-FY 1991 report

    Energy Technology Data Exchange (ETDEWEB)

    Ashwood, T.L.; Wickliff, D.S.; Morrissey, C.M.

    1991-10-01

    This report summarizes the activities of the Active Sites Environmental Monitoring Program (ASEMP) from October 1990 through March 1991. The ASEMP was established in 1989 by Solid Waste Operations and the Environmental Sciences Division to provide early detection and performance monitoring at active low-level radioactive waste (LLW) disposal sites in Solid Waste Storage Area (SWSA) 6 and transuranic (TRU) waste storage sites in SWSA 5 as required by chapters II and III of US Department of Energy Order 5820.2A. Monitoring results continue to demonstrate the no LLW is being leached from the storage vaults on the tumulus pads. Loading of vaults on Tumulus II began during this reporting period and 115 vaults had been loaded by the end of March 1991.

  5. Site I Inactivation Impacts Calmodulin Calcium Binding and Activation of Bordetella pertussis Adenylate Cyclase Toxin.

    Science.gov (United States)

    Johns, Christian W; Finley, Natosha L

    2017-11-30

    Site I inactivation of calmodulin (CaM) was used to examine the importance of aspartic acid 22 at position 3 in CaM calcium binding, protein folding, and activation of the Bordetella pertussis adenylate cyclase toxin domain (CyaA-ACD). NMR calcium titration experiments showed that site I in the CaM mutant (D22A) remained largely unperturbed, while sites II, III, and IV exhibited calcium-induced conformational changes similar to wild-type CaM (CaMWt). Circular dichroism analyses revealed that D22A had comparable α -helical content to CaMWt, and only modest differences in α -helical composition were detected between CaMWt-CyaA-ACD and D22A-CyaA-ACD complexes. However, the thermal stability of the D22A-CyaA-ACD complex was reduced, as compared to the CaMWt-CyaA-ACD complex. Moreover, CaM-dependent activity of CyaA-ACD decreased 87% in the presence of D22A. Taken together, our findings provide evidence that D22A engages CyaA-ACD, likely through C -terminal mediated binding, and that site I inactivation exerts functional effects through the modification of stabilizing interactions that occur between N -terminal CaM and CyaA-ACD.

  6. Oxygen reduction and evolution at single-metal active sites

    DEFF Research Database (Denmark)

    Calle-Vallejo, F.; Martínez, J.I.; García Lastra, Juan Maria

    2013-01-01

    overpotentials and is made of precious materials. A possible solution is the use of non-noble electrocatalysts with single-metal active sites. Here, on the basis of DFT calculations of adsorbed intermediates and a thermodynamic analysis, we compare the oxygen reduction (ORR) and evolution (OER) activities...... of functionalized graphitic materials and gas-phase porphyrins with late transition metals. We find that both kinds of materials follow approximately the same activity trends, and active sites with transition metals from groups 7 to 9 may be good ORR and OER electrocatalysts. However, spin analyses show more...... flexibility in the possible oxidation states of the metal atoms in solid electrocatalysts, while in porphyrins they must be +2. These observations reveal that the catalytic activity of these materials is mainly due to nearest-neighbor interactions. Based on this, we propose that this class of electrocatalysts...

  7. Site preference of Zr in Ti3Al and phase stability of Ti2ZrAl

    Indian Academy of Sciences (India)

    Unknown

    Abstract. The site preference of Zr atoms in Ti3Al and the phase stability of Ti2ZrAl are examined using first-principles electronic structure total energy calculations. Of the sixteen possible ways in which Ti, Zr and. Al atoms can be arranged, in the lattice sites corresponding to D019 structure of Ti3Al, to obtain Ti2ZrAl, it is.

  8. Transportation risk assessment of radioactive wastes generated by the N-Reactor stabilization program at the Hanford Site, Washington

    International Nuclear Information System (INIS)

    Wheeler, T.

    1994-12-01

    The potential radiological and nonradiological risks associated with specific radioactive waste shipping campaigns at the Hanford Site are estimated. The shipping campaigns analyzed are associated with the transportation of wastes from the N-Reactor site at the 200-W Area, both within the Hanford Reservation, for disposal. The analysis is based on waste that would be generated from the N-Reactor stabilization program

  9. Remedial action plan and site design for stabilization of the inactive uranium processing site at Naturita, Colorado

    International Nuclear Information System (INIS)

    1994-03-01

    Attachment 3 Groundwater Hydrology Report describes the hydrogeology, water quality, and water resources at the processing site and Dry Flats disposal site. The Hydrological Services calculations contained in Appendix A of Attachment 3, are presented in a separate report. Attachment 4 Water Resources Protection Strategy describes how the remedial action will be in compliance with the proposed EPA groundwater standards

  10. Enhancement in catalytic activity of Aspergillus niger XynB by selective site-directed mutagenesis of active site amino acids.

    Science.gov (United States)

    Wu, Xiuyun; Tian, Zhennan; Jiang, Xukai; Zhang, Qun; Wang, Lushan

    2018-01-01

    XynB from Aspergillus niger ATCC1015 (AnXynB) is a mesophilic glycoside hydrolase (GH) family 11 xylanase which holds great potentials in a wide variety of industrial applications. In the present study, the catalytic activity and stability of AnXynB were improved by a combination of computational and experimental approaches. Virtual mutation and molecular dynamics simulations indicated that the introduction of Glu and Asn altered the interaction network at the - 3 subsite. Interestingly, the double mutant S41N/T43E displayed 72% increase in catalytic activity when compared to the wild type (WT). In addition, it also showed a better thermostability than the WT enzyme. Kinetic determination of the T43E and S41N/T43E mutants suggested that the higher xylanase activity is probably due to the increasing binding affinity of enzyme and substrate. Consequently, the enzyme activity and thermostability of AnXynB was both increased by selective site-directed mutagenesis at the - 3 subsite of its active site architecture which provides a good example for a successfully engineered enzyme for potential industrial application. Moreover, the molecular evolution approach adopted in this study led to the design of a library of sequences that captures a meaningful functional diversity in a limited number of protein variants.

  11. Endonuclease active site plasticity allows DNA cleavage with diverse alkaline Earth and transition metal ions.

    Science.gov (United States)

    Vasu, Kommireddy; Saravanan, Matheshwaran; Nagaraja, Valakunja

    2011-09-16

    A majority of enzymes show a high degree of specificity toward a particular metal ion in their catalytic reaction. However, Type II restriction endonuclease (REase) R.KpnI, which is the first member of the HNH superfamily of REases, exhibits extraordinary diversity in metal ion dependent DNA cleavage. Several alkaline earth and transition group metal ions induce high fidelity and promiscuous cleavage or inhibition depending upon their concentration. The metal ions having different ionic radii and co-ordination geometries readily replace each other from the enzyme's active site, revealing its plasticity. Ability of R.KpnI to cleave DNA with both alkaline earth and transition group metal ions having varied ionic radii could imply utilization of different catalytic site(s). However, mutation of the invariant His residue of the HNH motif caused abolition of the enzyme activity with all of the cofactors, indicating that the enzyme follows a single metal ion catalytic mechanism for DNA cleavage. Indispensability of His in nucleophile activation together with broad cofactor tolerance of the enzyme indicates electrostatic stabilization function of metal ions during catalysis. Nevertheless, a second metal ion is recruited at higher concentrations to either induce promiscuity or inhibit the DNA cleavage. Regulation of the endonuclease activity and fidelity by a second metal ion binding is a unique feature of R.KpnI among REases and HNH nucleases. The active site plasticity of R.KpnI opens up avenues for redesigning cofactor specificities and generation of mutants specific to a particular metal ion.

  12. Molecular Basis for Enzymatic Sulfite Oxidation -- HOW THREE CONSERVED ACTIVE SITE RESIDUES SHAPE ENZYME ACTIVITY

    Energy Technology Data Exchange (ETDEWEB)

    Bailey, Susan; Rapson, Trevor; Johnson-Winters, Kayunta; Astashkin, Andrei; Enemark, John; Kappler, Ulrike

    2008-11-10

    Sulfite dehydrogenases (SDHs) catalyze the oxidation and detoxification of sulfite to sulfate, a reaction critical to all forms of life. Sulfite-oxidizing enzymes contain three conserved active site amino acids (Arg-55, His-57, and Tyr-236) that are crucial for catalytic competency. Here we have studied the kinetic and structural effects of two novel and one previously reported substitution (R55M, H57A, Y236F) in these residues on SDH catalysis. Both Arg-55 and His-57 were found to have key roles in substrate binding. An R55M substitution increased Km(sulfite)(app) by 2-3 orders of magnitude, whereas His-57 was required for maintaining a high substrate affinity at low pH when the imidazole ring is fully protonated. This effect may be mediated by interactions of His-57 with Arg-55 that stabilize the position of the Arg-55 side chain or, alternatively, may reflect changes in the protonation state of sulfite. Unlike what is seen for SDHWT and SDHY236F, the catalytic turnover rates of SDHR55M and SDHH57A are relatively insensitive to pH (~;;60 and 200 s-1, respectively). On the structural level, striking kinetic effects appeared to correlate with disorder (in SDHH57A and SDHY236F) or absence of Arg-55 (SDHR55M), suggesting that Arg-55 and the hydrogen bonding interactions it engages in are crucial for substrate binding and catalysis. The structure of SDHR55M has sulfate bound at the active site, a fact that coincides with a significant increase in the inhibitory effect of sulfate in SDHR55M. Thus, Arg-55 also appears to be involved in enabling discrimination between the substrate and product in SDH.

  13. Evaluation of the geologic relations and seismotectonic stability of the Yucca Mountain area, Nevada Nuclear Waste Site Investigation (NNWSI)

    International Nuclear Information System (INIS)

    1988-10-01

    This report provides a summary of progress for the project ''Evaluation of the Geologic Relations and Seismotectonic Stability of the Yucca Mountain Area, Nevada Nuclear Waste Site Investigation (NNWSI)'' for the eighteen month period of January 1, 1987 to June 10, 1988. This final report was preceded by the final report for the initial six month period, July 1, 1986 to December 31, 1986 (submitted on January 25, 1987, and revised in June 1987). The general Task continued to coordinate project activities to meet general deadlines and responsibilities. The central office provided general secretarial support. The activities that were started during the first project period included expansion of the central copying facilities, growth of the central reprint, map, aerial and photograph collections, and some expansion of personal computer capabilities. The research and review accomplishments are mainly under the following tasks: quaternary tectonics, geochemical, mineral deposits, volcanic geology, seismology, tectonics, neotectonics, remote sensing, geotechnical assessments, geotechnical rock mass assessment, basinal studies, and strong ground motion

  14. Decentralized stabilization of semi-active vibrating structures

    Science.gov (United States)

    Pisarski, Dominik

    2018-02-01

    A novel method of decentralized structural vibration control is presented. The control is assumed to be realized by a semi-active device. The objective is to stabilize a vibrating system with the optimal rates of decrease of the energy. The controller relies on an easily implemented decentralized switched state-feedback control law. It uses a set of communication channels to exchange the state information between the neighboring subcontrollers. The performance of the designed method is validated by means of numerical experiments performed for a double cantilever system equipped with a set of elastomers with controlled viscoelastic properties. In terms of the assumed objectives, the proposed control strategy significantly outperforms the passive damping cases and is competitive with a standard centralized control. The presented methodology can be applied to a class of bilinear control systems concerned with smart structural elements.

  15. The stability of correlates of labour force activity.

    Science.gov (United States)

    Waghorn, G; Chant, D; Harris, M G

    2009-05-01

    To investigate the stability of correlates of labour force activity among people with affective and anxiety disorders, compared with healthy adults, between 1998 and 2003. Secondary analyses of multi-stage probability samples of community residents (n(1998)=37,580 and n(2003)=36,088) obtained from repeat administrations of an Australian population survey. Proportionally, fewer people with affective or anxiety disorders were employed compared with well controls. Extent of employment restrictions, sex, age left school, country of birth, age and educational attainment were strong correlates of labour force participation and current employment. These effects were stable despite improved labour market conditions in 2003. These results can inform decisions about access to substantial forms of employment assistance. Subgroups of people with anxiety and depression, with severe employment restrictions, low education, low language proficiency, aged 15-24 years, or aged 55 years or more, may require greater access to substantial employment assistance.

  16. Erythrocyte membrane stabilization effect and antioxidant activity of methyl methacrylate

    International Nuclear Information System (INIS)

    Popov, B.

    2004-01-01

    Methyl methacrylate (MMK) is a synthetic product with mild impact on human health that is not well studied on cellular basis. Here, human erythrocytes were used to investigate the effects MMK exerts on acid and heat-induced hemolysis. Biphasic effect of MMK was observed for acid-induced hemolysis; i.e., protection at low (0 - 0.05% v/v) and stimulation at higher (0.1- 0.4% v/v) concentrations. The maximal protective effect was produced at 0.03% (v/v). At this concentration MMK increased the temperatures of heat denaturation of erythrocyte membrane proteins, spectrin and integral proteins, by about 2 0 C and inhibited the heat-induced hemolysis by 20 %. This membrane stabilization effect of MMK is similar to that produced by some anti-inflammatory and antirheumatic drugs. The increased acid resistance possibly indicated anti-oxidant properties of MMK. The nonenzymatic antioxidant activity test evidenced that MMK has no superoxide dismutase-like activity but demonstrates strong catalase-like activity (about 900 kU/mmol at 0.05-0.1 mmol/l concentration). The results indicate that at low concentration MMK exerts benign effect on cellular membrane that could find therapeutic usage. (author)

  17. Folding and activity of hybrid sequence, disulfide-stabilized peptides

    Energy Technology Data Exchange (ETDEWEB)

    Pease, J.H.B.; Storrs, R.W.; Wemmer, D.E. (Univ. of California, Berkeley (USA))

    1990-08-01

    Peptides have been synthesized that have hybrid sequences, partially derived from the bee venom peptide apamin and partially from the S peptide of ribonuclease A. The hybrid peptides were demonstrated by NMR spectroscopy to fold, forming the same disulfides and basic three-dimensional structure as native apamin, containing a {beta}-turn and an {alpha}-helix. These hybrids were active in complementing S protein, reactivating nuclease activity. In addition, the hybrid peptide was effective in inducing antibodies that cross-react with the RNase, without conjugation to a carrier protein. The stability of the folded structure of this peptide suggests that it should be possible to elicit antibodies that will react not only with a specific sequence, but also with a specific secondary structure. Hybrid sequence peptides also provide opportunities to study separately nucleation and propagation steps in formation of secondary structure. The authors show that in S peptide the {alpha}-helix does not end abruptly but rather terminates gradually over four or five residues. In general, these hybrid sequence peptides, which fold predictably because of disulfide bond formation, can provide opportunities for examining structure - function relationships for many biologically active sequences.

  18. Folding and activity of hybrid sequence, disulfide-stabilized peptides

    International Nuclear Information System (INIS)

    Pease, J.H.B.; Storrs, R.W.; Wemmer, D.E.

    1990-01-01

    Peptides have been synthesized that have hybrid sequences, partially derived from the bee venom peptide apamin and partially from the S peptide of ribonuclease A. The hybrid peptides were demonstrated by NMR spectroscopy to fold, forming the same disulfides and basic three-dimensional structure as native apamin, containing a β-turn and an α-helix. These hybrids were active in complementing S protein, reactivating nuclease activity. In addition, the hybrid peptide was effective in inducing antibodies that cross-react with the RNase, without conjugation to a carrier protein. The stability of the folded structure of this peptide suggests that it should be possible to elicit antibodies that will react not only with a specific sequence, but also with a specific secondary structure. Hybrid sequence peptides also provide opportunities to study separately nucleation and propagation steps in formation of secondary structure. The authors show that in S peptide the α-helix does not end abruptly but rather terminates gradually over four or five residues. In general, these hybrid sequence peptides, which fold predictably because of disulfide bond formation, can provide opportunities for examining structure - function relationships for many biologically active sequences

  19. Active Sites Environmental Monitoring Program: FY 1990 annual report

    International Nuclear Information System (INIS)

    Wickliff, D.S.; Morrissey, C.M.; Ashwood, T.L.

    1991-10-01

    Chapter 3 of US Department of Energy (DOE) Order 5820.2A (DOE 1988) sets forth requirements for environmental monitoring of active low-level waste (LLW) disposal sites. Active sites are defined as those LLW facilities that were in use on or after the date of the order (September 1988). The transuranic (TRU) waste storage areas in Solid Waste Storage Area (SWSA) 5 North are covered by Chap. 2 of the order. In both chapters, monitoring is required to provide for early warning of leaks before those leaks pose a threat to human health or the environment. Chapter 3 also requires that monitoring be conducted to evaluate the short- and long-term performance of LLW disposal facilities. In accordance with this order, the Solid Waste Operations Department at Oak Ridge National Laboratory (ORNL) has established an Active Sites Environmental Monitoring Program (ASEMP) that is implemented by staff of the Environmental Sciences Division (ESD) at ORNL. This report summarizes data from ASEMP monitoring activities for the final 6 months of FY 1990. A brief summary of the monitoring methodology for each site is presented also

  20. Active site modeling in copper azurin molecular dynamics simulations

    NARCIS (Netherlands)

    Rizzuti, B; Swart, M; Sportelli, L; Guzzi, R

    Active site modeling in molecular dynamics simulations is investigated for the reduced state of copper azurin. Five simulation runs (5 ns each) were performed at room temperature to study the consequences of a mixed electrostatic/constrained modeling for the coordination between the metal and the

  1. Energy transfer at the active sites of heme proteins

    International Nuclear Information System (INIS)

    Dlott, D.D.; Hill, J.R.

    1995-01-01

    Experiments using a picosecond pump-probe apparatus at the Picosecond Free-electron Laser Center at Stanford University, were performed to investigate the relaxation of carbon monoxide bound to the active sites of heme proteins. The significance of these experiments is two-fold: (1) they provide detailed information about molecular dynamics occurring at the active sites of proteins; and (2) they provide insight into the nature of vibrational relaxation processes in condensed matter. Molecular engineering is used to construct various molecular systems which are studied with the FEL. We have studied native proteins, mainly myoglobin obtained from different species, mutant proteins produced by genetic engineering using recombinant DNA techniques, and a variety of model systems which mimic the structures of the active sites of native proteins, which are produced using molecular synthesis. Use of these different systems permits us to investigate how specific molecular structural changes affect dynamical processes occurring at the active sites. This research provides insight into the problems of how different species needs are fulfilled by heme proteins which have greatly different functionality, which is induced by rather small structural changes

  2. Modelling the active site properties of dopamine b-hydroxylase

    Indian Academy of Sciences (India)

    Administrator

    Dopamine b-hydroxylase (DbH) is a copper-containing glycoprotein that hydroxylates dopamine to norepinephrine 1,2. Based on spectroscopic studies the active site of the metalloenzyme is proposed to have two copper centres. The enzyme in the oxidized dicopper(II) form gets reduced to the dicopper(I) unit by ascorbate ...

  3. The nature of the active site in heterogeneous metal catalysis

    DEFF Research Database (Denmark)

    Nørskov, Jens Kehlet; Bligaard, Thomas; Larsen, Britt Hvolbæk

    2008-01-01

    This tutorial review, of relevance for the surface science and heterogeneous catalysis communities, provides a molecular-level discussion of the nature of the active sites in metal catalysis. Fundamental concepts such as "Bronsted-Evans-Polanyi relations'' and "volcano curves'' are introduced...

  4. Leachate characterization of active and closed dump sites in Port ...

    African Journals Online (AJOL)

    This study characterizes the leachate quality of both active and closed dump sites in Port Harcourt City. Leachates were sampled from the base of the dum psites and analysed, pH, dissolved oxygen (DO), electrical conductivity and total dissolved solids were determined on the samples in-situ. While chloride, sulphate ...

  5. Functional and catalytic active sites prediction and docking analysis ...

    African Journals Online (AJOL)

    Bioinformatics

    2015-07-01

    Jul 1, 2015 ... African Journal of Biotechnology. Full Length Research Paper. Functional and catalytic active sites prediction and docking analysis of azoreductase enzyme in. Pseudomonas putida with a variety of commercially available azodyes. Bikash Thakuria, Chandra J Singha, Premchand Maisnam and Samrat ...

  6. Use of phytoproductivity data in the choice of native plant species to restore a degraded coal mining site amended with a stabilized industrial organic sludge.

    Science.gov (United States)

    Chiochetta, Claudete G; Toumi, Hela; Böhm, Renata F S; Engel, Fernanda; Poyer-Radetski, Gabriel; Rörig, Leonardo R; Adani, Fabrizio; Radetski, Claudemir M

    2017-11-01

    Coal mining-related activities result in a degraded landscape and sites associated with large amounts of dumped waste material. The arid soil resulting from acid mine drainage affects terrestrial and aquatic ecosystems, and thus, site remediation programs must be implemented to mitigate this sequential deleterious processes. A low-cost alternative material to counterbalance the affected physico-chemical-microbiological aspects of the degraded soil is the amendment with low contaminated and stabilized industrial organic sludge. The content of nutrients P and N, together with stabilized organic matter, makes this material an excellent fertilizer and soil conditioner, fostering biota colonization and succession in the degraded site. However, choice of native plant species to restore a degraded site must be guided by some minimal criteria, such as plant survival/adaptation and plant biomass productivity. Thus, in this 3-month study under environmental conditions, phytoproductivity tests with five native plant species (Surinam cherry Eugenia uniflora L., C. myrianthum-Citharexylum myrianthum, Inga-Inga spp., Brazilian peppertree Schinus terebinthifolius, and Sour cherry Prunus cerasus) were performed to assess these criteria, and additional biochemical parameters were measured in plant tissues (i.e., protein content and peroxidase activity) exposed to different soil/sludge mixture proportions. The results show that three native plants were more adequate to restore vegetation on degraded sites: Surinam cherry, C. myrianthum, and Brazilian peppertree. Thus, this study demonstrates that phytoproductivity tests associated with biochemical endpoint measurements can help in the choice of native plant species, as well as aiding in the choice of the most appropriate soil/stabilized sludge proportion in order to optimize biomass production.

  7. Insights into the glycyl radical enzyme active site of benzylsuccinate synthase: a computational study.

    Science.gov (United States)

    Bharadwaj, Vivek S; Dean, Anthony M; Maupin, C Mark

    2013-08-21

    The fumarate addition reaction, catalyzed by the enzyme benzylsuccinate synthase (BSS), is considered to be one of the most intriguing and energetically challenging reactions in biology. BSS belongs to the glycyl radical enzyme family and catalyzes the fumarate addition reaction, which enables microorganisms to utilize hydrocarbons as an energy source under anaerobic conditions. Unfortunately, the extreme sensitivity of the glycyl radical to oxygen has hampered the structural and kinetic characterization of BSS, thereby limiting our knowledge on this enzyme. To enhance our molecular-level understanding of BSS, a computational approach involving homology modeling, docking studies, and molecular dynamics (MD) simulations has been used to deduce the structure of BSS's catalytic subunit (BSSα) and illuminate the molecular basis for the fumarate addition reaction. We have identified two conserved and distinct binding pockets at the BSSα active site: a hydrophobic pocket for toluene binding and a polar pocket for fumaric acid binding. Subsequent dynamical and energetic evaluations have identified Glu509, Ser827, Leu390, and Phe384 as active site residues critical for substrate binding. The orientation of substrates at the active site observed in MD simulations is consistent with experimental observations of the syn addition of toluene to fumaric acid. It is also found that substrate binding tightens the active site and restricts the conformational flexibility of the thiyl radical, leading to hydrogen transfer distances conducive to the proposed reaction mechanism. The stability of substrates at the active site and the occurrence of feasible radical transfer distances between the thiyl radical, substrates, and the active site glycine indicate a substrate-assisted radical transfer pathway governing fumarate addition.

  8. Remedial action plan and site design for stabilization of the inactive uranium mill tailings sites at Slick Rock, Colorado. Final report

    International Nuclear Information System (INIS)

    1996-08-01

    This document contains the page changes for Attachment 3, Ground Water Hydrology Report dated August, 1996 for the Remedial Action Plan and Site Design for Stabilization of the Inactive Uranium Mill Tailings at Slick Rock, Colorado. This portion of Attachment 3 contains the Table of Contents pages i and ii, and pages numbered 3-3 through 3-56 of the Ground Water Hydrology Report. Also included are the cover sheets for Appendix A, B, and C to Attachment 3

  9. Direct instrumental identification of catalytically active surface sites

    Science.gov (United States)

    Pfisterer, Jonas H. K.; Liang, Yunchang; Schneider, Oliver; Bandarenka, Aliaksandr S.

    2017-09-01

    The activity of heterogeneous catalysts—which are involved in some 80 per cent of processes in the chemical and energy industries—is determined by the electronic structure of specific surface sites that offer optimal binding of reaction intermediates. Directly identifying and monitoring these sites during a reaction should therefore provide insight that might aid the targeted development of heterogeneous catalysts and electrocatalysts (those that participate in electrochemical reactions) for practical applications. The invention of the scanning tunnelling microscope (STM) and the electrochemical STM promised to deliver such imaging capabilities, and both have indeed contributed greatly to our atomistic understanding of heterogeneous catalysis. But although the STM has been used to probe and initiate surface reactions, and has even enabled local measurements of reactivity in some systems, it is not generally thought to be suited to the direct identification of catalytically active surface sites under reaction conditions. Here we demonstrate, however, that common STMs can readily map the catalytic activity of surfaces with high spatial resolution: we show that by monitoring relative changes in the tunnelling current noise, active sites can be distinguished in an almost quantitative fashion according to their ability to catalyse the hydrogen-evolution reaction or the oxygen-reduction reaction. These data allow us to evaluate directly the importance and relative contribution to overall catalyst activity of different defects and sites at the boundaries between two materials. With its ability to deliver such information and its ready applicability to different systems, we anticipate that our method will aid the rational design of heterogeneous catalysts.

  10. From 3D to 2D Co and Ni Oxyhydroxide Catalysts: Elucidation of the Active Site and Influence of Doping on the Oxygen Evolution Activity

    DEFF Research Database (Denmark)

    Tripkovic, Vladimir; Hansen, Heine Anton; Vegge, Tejs

    2017-01-01

    Layered oxyhydroxides (ox-hys) of Ni and Co are among the most active catalysts for oxygen evolution in alkaline media. Their activities can be further tuned by delamination into single-layer oxide sheets or by means of doping. The active site for the reaction and how doping and delamination...... investigate the role of terrace and edge sites and use stability, catalytic activity, and electronic conductivity as evaluation criteria to pinpoint the best catalysts. We arrive at several important conclusions: the ox-hy surface is fully oxidized under oxygen evolution conditions, bulk terraces...

  11. Development of corrective measures and site stabilization technologies for shallow land burial facilities at semiarid sites: summary paper

    International Nuclear Information System (INIS)

    Nyhan, J.W.; Abeele, W.V.

    1987-01-01

    The overall purpose of the corrective measures task performed for the national Low-Level Waste Management Program (NLLWMP) has been to develop and test methods that can be used to correct any actual or anticipated problems with new and existing shallow land burial (SLB) sites in a semiarid environment. These field tests have not only evaluated remedial actions, but have also investigated phenomena suspected of being a possible problem at semiarid SLB sites. The approach the authors have taken in developing remedial action and site closure technologies for low-level waste sites is to recognize the physical and biological processes affecting site integrity are interdependent, and therefore, cannot be treated as separate problems. More specifically the field experiments performed for this task were to identify, evaluate, and model erosion control technologies, field test second generation biointrusion barriers, determine by field experiments the extent of upward radionuclide migration due to moisture cycling, and measure the effects of subsidence on remedial action of other system components. In the following sections of this final task summary report, the authors describe the progress made in establishing the facility in which many of these field experiments were performed, the Los Alamos Experimental Engineered Test Facility (EETF), as well as a brief description of the four research areas encompassed by this task. 45 references, 4 figures

  12. Remedial action plan and site design for stabilization of the inactive uranium processing site at Naturita, Colorado

    International Nuclear Information System (INIS)

    1994-03-01

    The uranium processing site near Naturita, Colorado, is one of 24 inactive uranium mill sites designated to be cleaned up by the US Department of Energy (DOE) under the Uranium Mill Tailings Radiation Control Act of 1978 (UMTRCA), 42 USC section 7901 et seq. Part of the UMTRCA requires that the US Nuclear Regulatory Commission (NRC) concur with the DOE's remedial action plan (RAP) and certify that the remedial action conducted at the site complies with the standards promulgated by the US Environmental Protection Agency (EPA). Included in the RAP is this Remedial Action Selection Report (RAS), which describes the proposed remedial action for the Naturita site. An extensive amount of data and supporting information has been generated and evaluated for this remedial action. These data and supporting information are not incorporated into this single document but are included or referenced in the supporting documents. The RAP consists of this RAS and four supporting documents or attachments. This Attachment 2, Geology Report describes the details of geologic, geomorphic, and seismic conditions at the Dry Flats disposal site

  13. New route toward building active ruthenium nanoparticles on ordered mesoporous carbons with extremely high stability

    Science.gov (United States)

    Yang, Ying; Sun, Chengjun; Ren, Yang; Hao, Shijie; Jiang, Daqiang

    2014-04-01

    Creating highly active and stable metal catalysts is a persistent goal in the field of heterogeneous catalysis. However, a real catalyst can rarely achieve both of these qualities simultaneously due to limitations in the design of the active site and support. One method to circumvent this problem is to fabricate firmly attached metal species onto the voids of a mesoporous support formed simultaneously. In this study, we developed a new type of ruthenium catalyst that was firmly confined by ordered mesoporous carbons through the fabrication of a cubic Ia3d chitosan-ruthenium-silica mesophase before pyrolysis and silica removal. This facile method generates fine ruthenium nanoparticles (ca. 1.7 nm) that are homogeneously dispersed on a mesoporous carbonaceous framework. This ruthenium catalyst can be recycled 22 times without any loss of reactivity, showing the highest stability of any metal catalysts; this catalyst displays a high activity (23.3 molLAh-1gmetal-1) during the catalytic hydrogenation of levulinic acid (LA) when the metal loading is 6.1 wt%. Even at an ultralow loading (0.3 wt%), this catalyst still outperforms the most active known Ru/C catalyst. This work reveals new possibilities for designing and fabricating highly stable and active metal catalysts by creating metal sites and mesoporous supports simultaneously.

  14. Remedial Action Plan and site design for stabilization of the inactive uranium mill tailings site at Gunnison, Colorado. Attachment 2, Geology report: Final report

    Energy Technology Data Exchange (ETDEWEB)

    1992-10-01

    Detailed investigations of geologic, geomorphic, and seismic conditions at the Landfill disposal site were conducted. The purpose of these studies was basic site characterization and identification of potential geologic hazards that could affect long-term site stability. Subsequent engineering studies, such as analyses of hydrologic and liquefaction hazards, used the data developed in these studies. The geomorphic analysis was employed in the design of effective erosion protection. Studies of the regional and local seismotectonic setting, which included a detailed search for possible capable faults within a 65-kilometer (km) (40-mile) radius of the site, provided the basis for seismic design parameters. The scope of work performed included the following: Compilation and analysis of previous published and unpublished geologic literature and maps. Review of historical and instrumental earthquake data. Review of site-specific subsurface geologic data, including lithologic and geophysical logs of exploratory boreholes advanced in the site area. Photogeologic interpretations of existing conventional aerial photographs. Ground reconnaissance and mapping of the site region.

  15. Remedial Action Plan and site design for stabilization of the inactive uranium mill tailings site at Durango, Colorado: Attachment 2, Geology report

    International Nuclear Information System (INIS)

    1991-12-01

    Detailed investigations of geologic, geomorphic, and seismic conditions at the Bodo Canyon disposal site were conducted. The purpose of these investigations was basic site characterization and identification of potential geologic hazards that could affect long-term site stability. Subsequent engineering studies, such as analyses of hydrologic and liquefaction hazards, used the data developed in these studies. The geomorphic analysis was employed in the design of effective erosion protection. Studies of the regional and local seismotectonic setting, which included a detailed search for possible capable faults within a 65 kilometer radius of the site, provided the basis for seismic design parameters. The scope of work performed included the following: Compilation and analysis of previous published and unpublished geologic literature and maps; Review of historical and instrumental earthquake data; Review of site-specific subsurface geologic data, including lithologic and geophysical logs of exploratory boreholes advanced in the site area; Photogeologic interpretations of existing conventional aerial photographs; and, Ground reconnaissance and mapping of the site region

  16. Iron metallodrugs: stability, redox activity and toxicity against Artemia salina.

    Directory of Open Access Journals (Sweden)

    Hector Aguilar Vitorino

    Full Text Available Iron metallodrugs comprise mineral supplements, anti-hypertensive agents and, more recently, magnetic nanomaterials, with both therapeutic and diagnostic roles. As biologically-active metal compounds, concern has been raised regarding the impact of these compounds when emitted to the environment and associated ecotoxicological effects for the fauna. In this work we assessed the relative stability of several iron compounds (supplements based on glucoheptonate, dextran or glycinate, as well as 3,5,5-trimethylhexanoyl (TMH derivatives of ferrocene against high affinity models of biological binding, calcein and aprotransferrin, via a fluorimetric method. Also, the redox-activity of each compound was determined in a physiologically relevant medium. Toxicity toward Artemia salina at different developmental stages was measured, as well as the amount of lipid peroxidation. Our results show that polymer-coated iron metallodrugs are stable, non-redox-active and non-toxic at the concentrations studied (up to 300 µM. However, TMH derivatives of ferrocene were less stable and more redox-active than the parent compound, and TMH-ferrocene displayed toxicity and lipid peroxidation to A. salina, unlike the other compounds. Our results indicate that iron metallodrugs based on polymer coating do not present direct toxicity at low levels of emission; however other iron species (eg. metallocenes, may be deleterious for aquatic organisms. We suggest that ecotoxicity depends more on metal speciation than on the total amount of metal present in the metallodrugs. Future studies with discarded metallodrugs should consider the chemical speciation of the metal present in the composition of the drug.

  17. Remedial action plan and site design for stabilization of the inactive uranium mill tailings site at Lakeview, Oregon: Volume 1, Text and appendices A through D

    International Nuclear Information System (INIS)

    Chernoff, A.R.

    1992-07-01

    The Lakeview inactive uranium processing site is in Lake County, Oregon, approximately one mile northwest of the town of Lakeview, sixteen miles north of the California-Oregon border, and 96 miles east of Klamath Falls. The total designated site covers an area of 258 acres consisting of a tailings pile (30 acres). seven evaporation ponds (69 acres), the mill buildings, and related structures. The mill buildings and other structures have been decontaminated and are currently being used by Goose Lake Lumber Company. The tailings pile at the processing site was originally stabilized by Atlantic Richfield with an earthen cover 18--24 inches thick. The average depth of the tailings, including the cover, varied from six to eight feet. There were estimated to be 662,000 cubic yards of tailings, windblown contaminated materials, and vicinity property materials. During remedial action under the Uranium Mill Tailings Remedial Action (UMTRA) Project, approximately 264,000 cubic yards of additional contaminated materials were identified from excavations required to remove thorium- and arsenic-contaminated soils. The remedial action for the Lakeview site consisted of the cleanup, relocation, consolidation, and stabilization of all residual radioactive materials and thorium- and arsenic-contaminated materials in a partially below-grade disposal cell at a location approximately seven miles northwest of the tailings site, identified as the Collins Ranch site. A cover, including a radon/infiltration barrier and rock layer for protection from erosion, was Placed on top of the tailings. A rock-soil matrix covers the topslope and provides a growth medium for vegetation. The US Department of Energy (DOE) will retain the license and surveillance and maintenance responsibilities for the final restricted site of 13 acres

  18. Remedial action plan and site design for stabilization of the inactive uranium mill tailings site at Lakeview, Oregon: Volume 1, Text and appendices A through D

    Energy Technology Data Exchange (ETDEWEB)

    Chernoff, A R [USDOE Albuquerque Operations Office, NM (United States). Uranium Mill Tailings Project Office; Ervin, C [Oregon State Dept. of Energy, Salem, OR (United States)

    1992-07-01

    The Lakeview inactive uranium processing site is in Lake County, Oregon, approximately one mile northwest of the town of Lakeview, sixteen miles north of the California-Oregon border, and 96 miles east of Klamath Falls. The total designated site covers an area of 258 acres consisting of a tailings pile (30 acres). seven evaporation ponds (69 acres), the mill buildings, and related structures. The mill buildings and other structures have been decontaminated and are currently being used by Goose Lake Lumber Company. The tailings pile at the processing site was originally stabilized by Atlantic Richfield with an earthen cover 18--24 inches thick. The average depth of the tailings, including the cover, varied from six to eight feet. There were estimated to be 662,000 cubic yards of tailings, windblown contaminated materials, and vicinity property materials. During remedial action under the Uranium Mill Tailings Remedial Action (UMTRA) Project, approximately 264,000 cubic yards of additional contaminated materials were identified from excavations required to remove thorium- and arsenic-contaminated soils. The remedial action for the Lakeview site consisted of the cleanup, relocation, consolidation, and stabilization of all residual radioactive materials and thorium- and arsenic-contaminated materials in a partially below-grade disposal cell at a location approximately seven miles northwest of the tailings site, identified as the Collins Ranch site. A cover, including a radon/infiltration barrier and rock layer for protection from erosion, was Placed on top of the tailings. A rock-soil matrix covers the topslope and provides a growth medium for vegetation. The US Department of Energy (DOE) will retain the license and surveillance and maintenance responsibilities for the final restricted site of 13 acres.

  19. STABILITY AND COMPATIBILITY OF TAXOL WITH VARIOUS DRUGS DURING SIMULATED Y-SITE ADMINISTRATION

    Directory of Open Access Journals (Sweden)

    JIN PIL BURM

    2005-01-01

    Full Text Available This study evaluates the compatibility and stability of Taxol with ondansetron, ranitidine, vancomycin and cephalosporins in 5% dextrose injection and 0.9% sodium chloride injection during simulated Y-site administration. Two stock solutions of Taxol 0.3 and 1.2 mg/mL and each stock solutions of ondansetron 0.03, 0.1 and 0.3 mg/mL, ranitidine 0.5 and 2 mg/mL, vancomycin 1, 5 and 10 mg/mL and cephalosporins 20 mg/mL were prepared in glass bottles. Two mL of Taxol stock solution was mixed with 2 mL of each stock solution. Samples were removed at room temperature at time zero, one, two, four and 12 hours for immediate assay. Taxol concentrations were analyzed by High Performance Liquid Chromatography. All solutions were prepared in triplicate, and each drug was assayed in duplicate. At the time of sampling assay and before any dilution, each sample was visually inspected for clarity, color and precipitation. The pH was also determined. Taxol in concentrations of 0.3 and 1.2 mg/mL was stable when mixed with either ondansetron (0.03, 0.1 or 0.3 mg/mL, as the hydrochloride salt, ranitidine (0.5 or 2.0 mg/mL, as the hydrochloride salt, vancomycin (1, 5 or 10 mg/mL, as the hydrochloride salt or cephalosporins 20 mg/mL and stored in glass containers for 12 hours. No precipitates, color changes, or haziness was seen. The changes in pH were minor.

  20. Remedial Action Plan and site design for stabilization of the inactive uranium mill tailings site at Gunnison, Colorado

    International Nuclear Information System (INIS)

    1992-10-01

    To achieve compliance with the proposed US Environmental Protection Agency (EPA) groundwater protection standards the US Department of Energy (DOE) proposes to meet background concentrations or the EPA maximum concentration limits (MCLS) for hazardous constituents in groundwater in the uppermost aquifer at the point of compliance (POC) at the Gunnison Uranium Mill Tailings Remedial Action (UMTRA) Project disposal site near Gunnison, Colorado. The proposed remedial action will ensure protection of human health and the environment. A summary of the principal features of the water resources protection strategy for the Gunnison disposal site is included in this report

  1. Fragment-based identification of determinants of conformational and spectroscopic change at the ricin active site

    Directory of Open Access Journals (Sweden)

    Soares Alexei S

    2007-11-01

    Full Text Available Abstract Background Ricin is a potent toxin and known bioterrorism threat with no available antidote. The ricin A-chain (RTA acts enzymatically to cleave a specific adenine base from ribosomal RNA, thereby blocking translation. To understand better the relationship between ligand binding and RTA active site conformational change, we used a fragment-based approach to find a minimal set of bonding interactions able to induce rearrangements in critical side-chain positions. Results We found that the smallest ligand stabilizing an open conformer of the RTA active site pocket was an amide group, bound weakly by only a few hydrogen bonds to the protein. Complexes with small amide-containing molecules also revealed a switch in geometry from a parallel towards a splayed arrangement of an arginine-tryptophan cation-pi interaction that was associated with an increase and red-shift in tryptophan fluorescence upon ligand binding. Using the observed fluorescence signal, we determined the thermodynamic changes of adenine binding to the RTA active site, as well as the site-specific binding of urea. Urea binding had a favorable enthalpy change and unfavorable entropy change, with a ΔH of -13 ± 2 kJ/mol and a ΔS of -0.04 ± 0.01 kJ/(K*mol. The side-chain position of residue Tyr80 in a complex with adenine was found not to involve as large an overlap of rings with the purine as previously considered, suggesting a smaller role for aromatic stacking at the RTA active site. Conclusion We found that amide ligands can bind weakly but specifically to the ricin active site, producing significant shifts in positions of the critical active site residues Arg180 and Tyr80. These results indicate that fragment-based drug discovery methods are capable of identifying minimal bonding determinants of active-site side-chain rearrangements and the mechanistic origins of spectroscopic shifts. Our results suggest that tryptophan fluorescence provides a sensitive probe for the

  2. Sleeping site selection by agile gibbons: the influence of tree stability, fruit availability and predation risk.

    Science.gov (United States)

    Cheyne, Susan M; Höing, Andrea; Rinear, John; Sheeran, Lori K

    2012-01-01

    Primates spend a significant proportion of their lives at sleeping sites: the selection of a secure and stable sleeping tree can be crucial for individual survival and fitness. We measured key characteristics of all tree species in which agile gibbons slept, including exposure of the tree crown, root system, height, species and presence of food. Gibbons most frequently slept in Dipterocarpaceae and Fabaceae trees and preferentially chose trees taller than average, slept above the mean canopy height and showed a preference for liana-free trees. These choices could reflect avoidance of competition with other frugivores, but we argue these choices reflect gibbons prioritizing avoidance of predation. The results highlight that gibbons are actively selecting and rejecting sleeping trees based on several characteristics. The importance of the presence of large trees for food is noted and provides insight into gibbon antipredatory behaviour. Copyright © 2013 S. Karger AG, Basel.

  3. Mapping the active site of vaccinia virus RNA triphosphatase

    International Nuclear Information System (INIS)

    Gong Chunling; Shuman, Stewart

    2003-01-01

    The RNA triphosphatase component of vaccinia virus mRNA capping enzyme (the product of the viral D1 gene) belongs to a family of metal-dependent phosphohydrolases that includes the RNA triphosphatases of fungi, protozoa, Chlorella virus, and baculoviruses. The family is defined by two glutamate-containing motifs (A and C) that form the metal-binding site. Most of the family members resemble the fungal and Chlorella virus enzymes, which have a complex active site located within the hydrophilic interior of a topologically closed eight-stranded β barrel (the so-called ''triphosphate tunnel''). Here we queried whether vaccinia virus capping enzyme is a member of the tunnel subfamily, via mutational mapping of amino acids required for vaccinia triphosphatase activity. We identified four new essential side chains in vaccinia D1 via alanine scanning and illuminated structure-activity relationships by conservative substitutions. Our results, together with previous mutational data, highlight a constellation of six acidic and three basic amino acids that likely compose the vaccinia triphosphatase active site (Glu37, Glu39, Arg77, Lys107, Glu126, Asp159, Lys161, Glu192, and Glu194). These nine essential residues are conserved in all vertebrate and invertebrate poxvirus RNA capping enzymes. We discerned no pattern of clustering of the catalytic residues of the poxvirus triphosphatase that would suggest structural similarity to the tunnel proteins (exclusive of motifs A and C). We infer that the poxvirus triphosphatases are a distinct lineage within the metal-dependent RNA triphosphatase family. Their unique active site, which is completely different from that of the host cell's capping enzyme, recommends the poxvirus RNA triphosphatase as a molecular target for antipoxviral drug discovery

  4. A three-dimensional model of mammalian tyrosinase active site accounting for loss of function mutations.

    Science.gov (United States)

    Schweikardt, Thorsten; Olivares, Concepción; Solano, Francisco; Jaenicke, Elmar; García-Borrón, José Carlos; Decker, Heinz

    2007-10-01

    Tyrosinases are the first and rate-limiting enzymes in the synthesis of melanin pigments responsible for colouring hair, skin and eyes. Mutation of tyrosinases often decreases melanin production resulting in albinism, but the effects are not always understood at the molecular level. Homology modelling of mouse tyrosinase based on recently published crystal structures of non-mammalian tyrosinases provides an active site model accounting for loss-of-function mutations. According to the model, the copper-binding histidines are located in a helix bundle comprising four densely packed helices. A loop containing residues M374, S375 and V377 connects the CuA and CuB centres, with the peptide oxygens of M374 and V377 serving as hydrogen acceptors for the NH-groups of the imidazole rings of the copper-binding His367 and His180. Therefore, this loop is essential for the stability of the active site architecture. A double substitution (374)MS(375) --> (374)GG(375) or a single M374G mutation lead to a local perturbation of the protein matrix at the active site affecting the orientation of the H367 side chain, that may be unable to bind CuB reliably, resulting in loss of activity. The model also accounts for loss of function in two naturally occurring albino mutations, S380P and V393F. The hydroxyl group in S380 contributes to the correct orientation of M374, and the substitution of V393 for a bulkier phenylalanine sterically impedes correct side chain packing at the active site. Therefore, our model explains the mechanistic necessity for conservation of not only active site histidines but also adjacent amino acids in tyrosinase.

  5. Decommissioning and decontamination activity, Gnome Site, Eddy County, New Mexico

    International Nuclear Information System (INIS)

    1978-10-01

    The purpose of this assessment is to present a brief description of the proposed activity and its potential impacts on the environment. This assessment will constitute an evaluation as to whether or not a formal Environmental Statement need be prepared. As background to the proposed activity, Project Gnome was an underground nuclear test conducted in December 1961 as part of the PLOWSHARE Program. The project site is located about 25 miles southeast of Carlsbad, New Mexico. By means of an excavated shaft and tunnel, a 3-kiloton nuclear explosive was emplaced and detonated in a salt bed about 1200 feet below the surface. The uncontaminated rock and salt muck from the original excavation and subsequent contaminated muck and minor construction debris from reentry activities into the nuclear cavity is commingled and stored in a pile near the Gnome/Coach Shaft. Other areas on the site are known to have been contaminated. In 1969, a program was conducted to cleanup and dispose of all surface contamination to whatever depth it occurred in excess of 0.1 mR/hr. Contaminated materials and soil were collected and disposed into the Gnome shaft, which was filled and sealed. Since then, NV has proposed to DOE/HQ much lower criteria for residual radioactive contamination for the Gnome Site. These proposed criteria were to collect and dispose of surficial materials which contain more than 2 x 10 -5 microcuries per gram of soil for beta/gamma emitters and 3 x 10 -2 microcuries per milliliter of tritium in soil moisture. According to the latest reconnaissance in 1972, low concentrations of Cs-137, Sr-90 and tritium were present at various locations on the site in excess of these proposed guidelines. Other operational areas within the site are suspected of containing radioactive contamination in much lesser volume, which are to be determined by careful probing and monitoring, as described in the next section

  6. Redesigned and chemically-modified hammerhead ribozymes with improved activity and serum stability

    Directory of Open Access Journals (Sweden)

    Stewart Tom S

    2004-12-01

    Full Text Available Abstract Background Hammerhead ribozymes are RNA-based molecules which bind and cleave other RNAs specifically. As such they have potential as laboratory reagents, diagnostics and therapeutics. Despite having been extensively studied for 15 years or so, their wide application is hampered by their instability in biological media, and by the poor translation of cleavage studies on short substrates to long RNA molecules. This work describes a systematic study aimed at addressing these two issues. Results A series of hammerhead ribozyme derivatives, varying in their hybridising arm length and size of helix II, were tested in vitro for cleavage of RNA derived from the carbamoyl phosphate synthetase II gene of Plasmodium falciparum. Against a 550-nt transcript the most efficient (t1/2 = 26 seconds was a miniribozyme with helix II reduced to a single G-C base pair and with twelve nucleotides in each hybridising arm. Miniribozymes of this general design were targeted to three further sites, and they demonstrated exceptional cleavage activity. A series of chemically modified derivatives was prepared and examined for cleavage activity and stability in human serum. One derivative showed a 103-fold increase in serum stability and a doubling in cleavage efficiency compared to the unmodified miniribozyme. A second was almost 104-fold more stable and only 7-fold less active than the unmodified parent. Conclusion Hammerhead ribozyme derivatives in which helix II is reduced to a single G-C base pair cleave long RNA substrates very efficiently in vitro. Using commonly available phosphoramidites and reagents, two patterns of nucleotide substitution in this derivative were identified which conferred both good cleavage activity against long RNA targets and good stability in human serum.

  7. Methodology for contaminated sites of military activity territories restoration

    International Nuclear Information System (INIS)

    Khrushchov, D. P.; Yushchenko, Yu. V.; Shekhunova, S. B.

    2002-01-01

    Major part of Eastern Europe countries meet environmental problems related to sites of military activity. Major part of these sites is characterised with degradation of natural landscapes and contamination of geological environment with toxic and hazardous waste representing actual and potential danger for population and environment. Actual danger is caused with localisation of toxic waste, hazardous materials and waste which are preventing normal land use. Potential danger is related to successive dispersion of contamination in biosphere as well as origin of new derivatives and products having toxic and hazardous properties. The list of such sites and objects comprises bases of land, air and naval forces. These objects include a network of infrastructures: storages of fuels and lubricants (surface, underground), filling stations, pipe lines, reparation stations, garages, decontamination stations, underground storages of different purposes, depots (for ammunition, chemical products), hospitals, constructions, firing grounds (tank, artillery, aircraft bombing etc.) and waste disposal sites. Special programs aimed at military industries and bases contaminated sites remediation have been carrying out in developed countries (USA, United Kingdom, Germany etc.). This experience was used in the frames of joint programs having been founded in several countries of Central and Eastern Europe (Chesh Republic, Slovakia, Lithuania etc.). (author)

  8. Evaluation of the geologic relations and seismotectonic stability of the Yucca Mountain area Nevada Nuclear Waste site investigation (NNWSI). Progress report, October 1, 1992--September 30, 1993

    International Nuclear Information System (INIS)

    1993-01-01

    This report provides a summary of progress for the project open-quotes Evaluation of the Geologic Relations and Seismotectonic Stability of the Yucca Mountain Area, Nevada Nuclear Waste Site Investigation (NNWSI).close quotes A similar report was previously provided for the period of 1 October 1991 to 30 September 1992. The report initially covers the activities of the General Task and is followed by sections that describe the progress of the other ongoing Tasks. This report summarizes the geologic and seismotectonic studies conducted at Yucca Mountain during the contract period including Quaternary tectonics, an evaluation of mineral resource potential of the area, caldera geology, and volcano-tectonic activity at and near the site. A report of basinal studies conducted during the contract period is also included. Selected papers are indexed separately for inclusion in the Energy Science and Technology Database

  9. Design of Single-Atom Co-N5Catalytic Site: A Robust Electrocatalyst for CO2Reduction with Nearly 100% CO Selectivity and Remarkable Stability.

    Science.gov (United States)

    Pan, Yuan; Lin, Rui; Chen, Yinjuan; Liu, Shoujie; Zhu, Wei; Cao, Xing; Chen, Wenxing; Wu, Konglin; Cheong, Weng-Chon; Wang, Yu; Zheng, Lirong; Luo, Jun; Lin, Yan; Liu, Yunqi; Liu, Chenguang; Li, Jun; Lu, Qi; Chen, Xin; Wang, Dingsheng; Peng, Qing; Chen, Chen; Li, Yadong

    2018-03-14

    We develop an N-coordination strategy to design a robust CO 2 reduction reaction (CO 2 RR) electrocatalyst with atomically dispersed Co-N 5 site anchored on polymer-derived hollow N-doped porous carbon spheres. Our catalyst exhibits high selectivity for CO 2 RR with CO Faradaic efficiency (FE CO ) above 90% over a wide potential range from -0.57 to -0.88 V (the FE CO exceeded 99% at -0.73 and -0.79 V). The CO current density and FE CO remained nearly unchanged after electrolyzing 10 h, revealing remarkable stability. Experiments and density functional theory calculations demonstrate single-atom Co-N 5 site is the dominating active center simultaneously for CO 2 activation, the rapid formation of key intermediate COOH* as well as the desorption of CO.

  10. Evaluation of the geologic relations and seismotectonic stability of the Yucca Mountain area Nevada Nuclear Waste site investigation (NNWSI). Progress report, October 1, 1992--September 30, 1993

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1993-09-30

    This report provides a summary of progress for the project {open_quotes}Evaluation of the Geologic Relations and Seismotectonic Stability of the Yucca Mountain Area, Nevada Nuclear Waste Site Investigation (NNWSI).{close_quotes} A similar report was previously provided for the period of 1 October 1991 to 30 September 1992. The report initially covers the activities of the General Task and is followed by sections that describe the progress of the other ongoing Tasks. This report summarizes the geologic and seismotectonic studies conducted at Yucca Mountain during the contract period including Quaternary tectonics, an evaluation of mineral resource potential of the area, caldera geology, and volcano-tectonic activity at and near the site. A report of basinal studies conducted during the contract period is also included. Selected papers are indexed separately for inclusion in the Energy Science and Technology Database.

  11. Stabilization of Harmonic Instability in AC Distribution Power System with Active Damping

    DEFF Research Database (Denmark)

    Yoon, Changwoo; Wang, Xiongfei; Bak, Claus Leth

    2015-01-01

    This paper deals stabilizing method of the interaction problems among the interconnected power electronics based power devices in a power distribution system. Even if each of the inverters in the network is stable individually, the combined network stability cannot be assured unless holistic...... stability assessment is performed. The impedance based stability criterion is used to study the effect of the active damping on the system stability. A benchmark of a Cigré power distribution network is modeled under the impedance based stability criterion and validated using the PSCAD/EMTDC simulation...

  12. Delta Learning Rule for the Active Sites Model

    OpenAIRE

    Lingashetty, Krishna Chaithanya

    2010-01-01

    This paper reports the results on methods of comparing the memory retrieval capacity of the Hebbian neural network which implements the B-Matrix approach, by using the Widrow-Hoff rule of learning. We then, extend the recently proposed Active Sites model by developing a delta rule to increase memory capacity. Also, this paper extends the binary neural network to a multi-level (non-binary) neural network.

  13. Active sites in char gasification: Final technical report

    Energy Technology Data Exchange (ETDEWEB)

    Wojtowicz, M.; Lilly, W.D.; Perkins, M.T.; Hradil, G.; Calo, J.M.; Suuberg, E.M.

    1987-09-01

    Among the key variables in the design of gasifiers and combustors is the reactivity of the chars which must be gasified or combusted. Significant loss of unburned char is unacceptable in virtually any process; the provision of sufficient residence time for complete conversion is essential. A very wide range of reactivities are observed, depending upon the nature of the char in a process. The current work focuses on furthering the understanding of gasification reactivities of chars. It has been well established that the reactivity of char to gasification generally depends upon three principal factors: (1) the concentration of ''active sites'' in the char; (2) mass transfer within the char; and (3) the type and concentration of catalytic impurities in the char. The present study primarily addresses the first factor. The subject of this research is the origin, nature, and fate of active sites in chars derived from parent hydrocarbons with coal-like structure. The nature and number of the active sites and their reactivity towards oxygen are examined in ''model'' chars derived from phenol-formaldehyde type resins. How the active sites are lost by the process of thermal annealing during heat treatment of chars are studied, and actual rate for the annealing process is derived. Since intrinsic char reactivities are of primary interest in the present study, a fair amount of attention was given to the model char synthesis and handling so that the effect of catalytic impurities and oxygen-containing functional groups in the chemical structure of the material were minimized, if not completely eliminated. The project would not be considered complete without comparing characteristic features of synthetic chars with kinetic behavior exhibited by natural chars, including coal chars.

  14. Exploiting Innocuous Activity for Correlating Users Across Sites

    OpenAIRE

    Goga , Oana; Lei , Howard; Parthasarathi , Sree Hari Krishnan; Friedland , Gerald; Sommer , Robin; Teixeira , Renata

    2013-01-01

    International audience; We study how potential attackers can identify accounts on different social network sites that all belong to the same user, exploiting only innocuous activity that inherently comes with posted content. We examine three specific features on Yelp, Flickr, and Twitter: the geo-location attached to a user's posts, the timestamp of posts, and the user's writing style as captured by language models. We show that among these three features the location of posts is the most powe...

  15. Stabilization

    Directory of Open Access Journals (Sweden)

    Muhammad H. Al-Malack

    2016-07-01

    Full Text Available Fuel oil flyash (FFA produced in power and water desalination plants firing crude oils in the Kingdom of Saudi Arabia is being disposed in landfills, which increases the burden on the environment, therefore, FFA utilization must be encouraged. In the current research, the effect of adding FFA on the engineering properties of two indigenous soils, namely sand and marl, was investigated. FFA was added at concentrations of 5%, 10% and 15% to both soils with and without the addition of Portland cement. Mixtures of the stabilized soils were thoroughly evaluated using compaction, California Bearing Ratio (CBR, unconfined compressive strength (USC and durability tests. Results of these tests indicated that stabilized sand mixtures could not attain the ACI strength requirements. However, marl was found to satisfy the ACI strength requirement when only 5% of FFA was added together with 5% of cement. When the FFA was increased to 10% and 15%, the mixture’s strength was found to decrease to values below the ACI requirements. Results of the Toxicity Characteristics Leaching Procedure (TCLP, which was performed on samples that passed the ACI requirements, indicated that FFA must be cautiously used in soil stabilization.

  16. Sulfur Polymer Stabilization/Solidification Treatability Study of Mercury Contaminated Soil from the Y-12 Site

    Energy Technology Data Exchange (ETDEWEB)

    Kalb P.; Milian, L.; Yim, S. P.

    2012-11-30

    As a result of past operations, the Department of Energy’s (DOE) Oak Ridge Y-12 National Security Complex (Y-12 Plant) has extensive mercury-contamination in building structures, soils, storm sewer sediments, and stream sediments, which are a source of pollution to the local ecosystem. Because of mercury’s toxicity and potential impacts on human health and the environment, DOE continues to investigate and implement projects to support the remediation of the Y-12 site.URS and #9122;CH2M Oak Ridge LLC (UCOR) under its prime contract with DOE has cleanup responsibilities on the DOE Oak Ridge Reservation and is investigating potential mercury-contaminated soil treatment technologies through an agreement with Babcock and Wilcox (B and W) Y-12, the Y-12 operating contractor to DOE. As part of its investigations, UCOR has subcontracted with Brookhaven National Laboratory (BNL) to conduct laboratory-scale studies evaluating the applicability of the Sulfur Polymer Stabilization/Solidification (SPSS) process using surrogate and actual mixed waste Y-12 soils containing mercury (Hg) at 135, 2,000, and 10,000 ppm.SPSS uses a thermoplastic sulfur binder to convert Hg to stable mercury sulfide (HgS) and solidifies the chemically stable product in a monolithic solid final waste form to reduce dispersion and permeability. Formulations containing 40 – 60 dry wt% Y-12 soil were fabricated and samples were prepared in triplicate for Environmental Protection Agency Toxicity Characteristic Leaching Procedure (TCLP) testing by an independent laboratory. Those containing 50 and 60 wt% soil easily met the study criteria for maximum allowable Hg concentrations (47 and 1 ppb, respectively compared with the TCLP limit of 200 ppb Hg). The lowest waste loading of 40 wt% yielded TCLP Hg concentrations slightly higher (240 ppb) than the allowable limit. Since the Y-12 soil tended to form clumps, the improved leaching at higher waste loadings was probably due to reduction in particle size

  17. The Stability and Antioxidant Activity of Anthocyanins from Blueberry

    Directory of Open Access Journals (Sweden)

    Rui He

    2010-01-01

    Full Text Available Anthocyanins from highbush blueberry (Vaccinium corymbosum L. have tremendous potential as natural colorants and functional food with pharmaceutical purposes in food applications. To exploit the potential for food applications, the stability and antioxidant activity of anthocyanins present in blueberries have been studied. The results indicate that anthocyanins from blueberry were stable against the low pH (≤5.0, NaCl (0.125–0.500 mol/L, sucrose (0.584–2.336 mol/L and preservative (sodium benzoate, 0.035–0.140 mol/L, but were sensitive to alkaline conditions (≥7.0, high temperature (≥80 °C, light (natural light, oxidizing agent (H2O2, 0.5–2.0 % and reducing agent (Na2SO3, 0.005–0.040 mol/L. At concentrations of 25 and 50 mg/mL, anthocyanins from blueberry could protect ECV-304 cells against oxidative damage induced by H2O2. These results suggest that anthocyanins from blueberry can be regarded as a potential colorant for some acidic (pH≤5.0 food products and could be used as health food to prevent diseases arising from oxidative processes.

  18. Steel passive state stability in activated fly ash mortars

    Directory of Open Access Journals (Sweden)

    Fernández-Jiménez, A.

    2010-12-01

    Full Text Available The present study explores the behaviour of structural steel embedded in Portland cement (OPC mortars and NaOH- and NaOH-waterglass-activated fly ash, in the presence and absence of 2 % Cl- (CaCl2. Variations were determined in the corrosion potential (Ecorr, linear polarization resistance (Rp and corrosion current density (icorr under different environmental conditions (90 days at 95 % relative humidity (RH, 30 days at ≈ 30 % RH, 760 days at ≈ 95 % RH. In the absence of Cl-, fly ash mortars were able to passivate steel reinforcement, although the stability of the passive state in changing environmental conditions was found to depend heavily on the activating solution used. Steel corrosion in the presence of 2 % Cl- was observed to be similar to the corrosion reported for the material in OPC mortars.

    En el presente trabajo se estudia el comportamiento del acero estructural embebido en morteros de cemento Pórtland (OPC y de cenizas volantes activadas con NaOH y una mezcla de NaOH y waterglass, en ausencia y en presencia de un 2% de Cl- (CaCl2. Se determino la evolución del potencial de corrosión (Ecorr, la resistencia de polarización lineal (Rp y la intensidad de corrosión (icorr, variando las condiciones ambientales (90 días al 95% de humedad relativa (HR-30 días a ≈ 30% HR- 760 días a ≈ 95% HR. En ausencia de Cl- los morteros de cenizas volantes activadas pueden pasivar los refuerzos de acero, si bien la estabilidad del estado pasivo ante cambios en las condiciones ambientales parece mostrar una fuerte dependencia de la solución activadora empleada. En presencia de un 2% de Cl- los aceros se corroen mostrando en comportamiento similar al observado en morteros en base OPC.

  19. Robust stability analysis of delayed Takagi-Sugeno fuzzy Hopfield neural networks with discontinuous activation functions.

    Science.gov (United States)

    Wu, Xiru; Wang, Yaonan; Huang, Lihong; Zuo, Yi

    2010-12-01

    In this paper, the global robust stability problem of delayed Takagi-Sugeno fuzzy Hopfield neural networks with discontinuous activation functions (TSFHNNs) is considered. Based on Lyapunov stability theory and M-matrices theory, we derive a stability criterion to guarantee the global robust stability of TSFHNNs. Compared with the existing literature, we remove the assumptions on the neuron activations such as Lipschitz conditions, bounded, monotonic increasing property or the assumption that the right-limit value is bigger than the left one at the discontinuous point. Finally, two numerical examples are given to show the effectiveness of the proposed stability results.

  20. Communication activities for NUMO's site selection process

    International Nuclear Information System (INIS)

    Takeuchi, Mitsuo; Okuyama, Shigeru; Kitayama, Kazumi; Kuba, Michiyoshi

    2004-01-01

    A siting program for geological disposal of high-level radioactive waste (HLW) in Japan has just started and is moving into a new stage of communication with the public. A final repository site will be selected via a stepwise process, as stipulated in the Specified Radioactive Waste Final Disposal Act promulgated in June 2000. Based on the Act, the site selection process of the Nuclear Waste Management Organization of Japan (NUMO, established in October 2000) will be carried out in the three steps: selection of Preliminary Investigation Areas (PIAs), selection of Detailed Investigation Areas (DIAs) and selection of the Repository Site. The Act also defines NUMO's responsibilities in terms of implementing the HLW disposal program in an open and transparent manner. NUMO fully understands the importance of public participation in its activities and is aiming to promote public involvement in the process of site selection based on a fundamental policy, which consists of 'adopting a stepwise approach', 'respecting the initiative of municipalities' and 'ensuring transparency in information disclosure'. This policy is clearly reflected in the adoption of an open solicitation approach for volunteer municipalities for Preliminary Investigation Areas (PIAs). NUMO made the official announcement of the start of its open solicitation program on 19 December 2002. This paper outlines how NUMO's activities are currently carried out with a view to encouraging municipalities to volunteer as PIAs and how public awareness of the safety of the HLW disposal is evaluated at this stage

  1. Seismic activity parameters of the Finnish potential repository sites

    International Nuclear Information System (INIS)

    Saari, J.

    2000-10-01

    Posiva Oy has started a project for estimating the possible earthquake induced rock movements on the deposition holes containing canisters of spent nuclear fuel. These estimates will be made for the four investigation sites, Romuvaara, Kivetty, Olkiluoto and Haestholmen. This study deals with the current and future seismicity associated with the above mentioned sites. Seismic belts that participate the seismic behaviour of the studied sites have been identified and the magnitude-frequency distributions of these belts have been estimated. The seismic activity parameters of the sites have been deduced from the characteristics of the seismic belts in order to forecast the seismicity during the next 100,000 years. The report discusses the possible earthquakes induced by future glaciation. The seismic interpretation seems to indicate that the previous postglacial faults in Finnish Lapland have been generated in compressional environment. The orientation of the rather uniform compression has been NW-SE, which coincide with the current stress field. It seems that, although the impact of postglacial crustal rebound must have been significant, the impact of plate tectonics has been dominant. A major assumption of this study has been that future seismicity will generally resemble the current seismicity. However, when the postglacial seismicity is concerned, the magnitude-frequency distribution is likely different and the expected maximum magnitude will be higher. Maximum magnitudes of future postglacial earthquakes have been approximated by strain release examinations. Seismicity has been examined within the framework of the lineament maps, in order to associate the future significant earthquakes with active fault zones in the vicinity of the potential repository sites. (orig.)

  2. Stability issues in Pd-based catalysts: the role of surface Pt in improving the stability and oxygen reduction reaction (ORR) activity.

    Science.gov (United States)

    Singh, R K; Rahul, R; Neergat, M

    2013-08-21

    Carbon-supported Pd and Pd3Co catalysts have been electrochemically characterized in 0.1 M HClO4 solution and we found that both catalysts were unstable. On repeated potential cycling, the electrochemical surface area of the catalysts decreases and the oxygen reduction reaction (ORR) activity suffers. To stabilize surface Pd atoms of both Pd and Pd3Co catalysts, we deposited Pt using adsorbed hydrogen on the catalytically active Pd sites. The Pt : Pd ratio of Pt-coated Pd and Pt-coated Pd3Co catalysts suggests half-a-monolayer coverage of Pt (two hydrogen atoms required for reducing a Pt(2+) ion). The Pt : Pd ratio of Pt-coated Pd3Co catalyst obtained from the simple geometrical hard sphere model, energy-dispersive X-ray spectroscopy (EDS) line scan and bulk EDS agrees very well with that calculated from the hydrogen desorption (H(des)) charge of Pd3Co. At the same time, the Pt : Pd ratio of Pt-coated Pd calculated from the H(des) charge of Pd catalyst is significantly lower than the ratio obtained from the other methods. Thus, the Pt : Pd ratio of the Pt-coated Pd catalyst estimated from the H(des) region of Pd is an underestimation of the composition. This suggests that Pd forms an electrochemically inactive species from the H(upd) region itself and Co in Pd3Co seems to stabilize Pd against oxidation by delaying the formation of electrochemically inactive species to higher potentials above the H(upd) region. The voltammograms along with the peroxide formation characteristics of the catalysts support the above observations. The deposited Pt on the surface of the Pd and Pd3Co catalysts masks active Pd sites from the electrochemical environment and even partial coverage with Pt improves the stability and ORR activity of the catalysts when compared to that of the respective Pt-free counterparts.

  3. Physical and chemical stability of palonosetron hydrochloride with dacarbazine and with methylprednisolone sodium succinate during simulated y-site administration.

    Science.gov (United States)

    Trissel, Lawrence A; Zhang, Yanping; Xu, Quanyun A

    2006-01-01

    The objective of this study was to evaluate the physical and chemical stability of mixtures of undiluted palonosetron hydrochloride 50 micrograms/mL with dacarbazine 4 mg/mL and with methylprednisolone sodium succinate 5 mg/mL in 5% dextrose injection during simulated Y-site administration. Triplicate test samples were prepared by admixing 7.5 mL of palonosetron hydrochloride with 7.5 mL of dacarbazine solution and, separately, methylprednisolone sodium succinate solution. Physical stability was assessed by using a multistep evaluation procedure that included both turbidimetric and particulate measurement as well as visual inspection. Chemical stability was assessed by using stability-indicating high-performance liquid chromatographic analytical techniques that determined drug concentrations. Evaluations were performed immediately after mixing and 1 and 4 hours after mixing. The palonosetron hydrochloride-dacarbazine samples were clear and colorless when viewed in normal fluorescent room light and when viewed with a Tyndall beam. Measured turbidities remained unchanged; particulate contents were low and exhibited little change. High-performance liquid chromatography analysis revealed that palonosetron hydrochloride and dacarbazine remained stable throughout the 4-hour test with no drug loss. Palonosetron hydrochloride is, therefore, physically compatible and chemically stable with dacarbazine during Y-site administration. Within 4 hours, the mixtures of palonosetron hydrochloride and methylprednisolone sodium succinate developed a microprecipitate that became a white precipitate visible to the unaided eye. The precipitate was analyzed and identified as methylprednisolone. Palonosetron hydrochloride is incompatible with methylprednisolone sodium succinate.

  4. State fusion entropy for continuous and site-specific analysis of landslide stability changing regularities

    Science.gov (United States)

    Liu, Yong; Qin, Zhimeng; Hu, Baodan; Feng, Shuai

    2018-04-01

    Stability analysis is of great significance to landslide hazard prevention, especially the dynamic stability. However, many existing stability analysis methods are difficult to analyse the continuous landslide stability and its changing regularities in a uniform criterion due to the unique landslide geological conditions. Based on the relationship between displacement monitoring data, deformation states and landslide stability, a state fusion entropy method is herein proposed to derive landslide instability through a comprehensive multi-attribute entropy analysis of deformation states, which are defined by a proposed joint clustering method combining K-means and a cloud model. Taking Xintan landslide as the detailed case study, cumulative state fusion entropy presents an obvious increasing trend after the landslide entered accelerative deformation stage and historical maxima match highly with landslide macroscopic deformation behaviours in key time nodes. Reasonable results are also obtained in its application to several other landslides in the Three Gorges Reservoir in China. Combined with field survey, state fusion entropy may serve for assessing landslide stability and judging landslide evolutionary stages.

  5. Remedial Action Plan and site design for stabilization of the inactive uranium mill tailings site at Durango, Colorado: Attachment 3, Groundwater hydrology report

    International Nuclear Information System (INIS)

    1991-12-01

    The US Environmental Protection Agency (EPA) has established health and environmental protection regulations to correct and prevent groundwater contamination resulting from processing activities at inactive uranium milling sites. According to the Uranium Mill Tailings Radiation Control Act of 1978, (UMTRCA) the US Department of Energy (DOE) is responsible for assessing the inactive uranium processing sites. The DOE has determined this assessment shall include information on hydrogeologic site characterization. The water resources protection strategy that describes how the proposed action will comply with the EPA groundwater protection standards is presented in Attachment 4. Site characterization activities discussed in this section include: Characterization of the hydrogeologic environment; characterization of existing groundwater quality; definition of physical and chemical characteristics of the potential contaminant source; and description of local water resources

  6. Remedial Action Plan and site design for stabilization of the inactive uranium mill tailings site at Durango, Colorado: Attachment 3, Groundwater hydrology report. Revised final report

    Energy Technology Data Exchange (ETDEWEB)

    1991-12-01

    The US Environmental Protection Agency (EPA) has established health and environmental protection regulations to correct and prevent groundwater contamination resulting from processing activities at inactive uranium milling sites. According to the Uranium Mill Tailings Radiation Control Act of 1978, (UMTRCA) the US Department of Energy (DOE) is responsible for assessing the inactive uranium processing sites. The DOE has determined this assessment shall include information on hydrogeologic site characterization. The water resources protection strategy that describes how the proposed action will comply with the EPA groundwater protection standards is presented in Attachment 4. Site characterization activities discussed in this section include: Characterization of the hydrogeologic environment; characterization of existing groundwater quality; definition of physical and chemical characteristics of the potential contaminant source; and description of local water resources.

  7. Current activities handbook: formerly utilized sites remedial action program

    Energy Technology Data Exchange (ETDEWEB)

    None

    1981-02-27

    This volume is one of a series produced under contract with the DOE, by Politech Corporation to develop a legislative and regulatory data base to assist the FUSRAP management in addressing the institutional and socioeconomic issues involved in carrying out the Formerly Utilized Sites Remedial Action Program. This Information Handbook series contains information about all relevant government agencies at the Federal and state levels, the pertinent programs they administer, each affected state legislature, and current Federal and state legislative and regulatory initiatives. This volume is a compilation of information about the activities each of the thirteen state legislatures potentially affected by the Formerly Utilized Sites Remedial Action Program. It contains a description of the state legislative procedural rules and a schedule of each legislative session; a summary of pending relevant legislation; the name and telephone number of legislative and state agency contacts; and the full text of all bills identified.

  8. Current activities handbook: formerly utilized sites remedial action program

    International Nuclear Information System (INIS)

    1981-01-01

    This volume is one of a series produced under contract with the DOE, by Politech Corporation to develop a legislative and regulatory data base to assist the FUSRAP management in addressing the institutional and socioeconomic issues involved in carrying out the Formerly Utilized Sites Remedial Action Program. This Information Handbook series contains information about all relevant government agencies at the Federal and state levels, the pertinent programs they administer, each affected state legislature, and current Federal and state legislative and regulatory initiatives. This volume is a compilation of information about the activities each of the thirteen state legislatures potentially affected by the Formerly Utilized Sites Remedial Action Program. It contains a description of the state legislative procedural rules and a schedule of each legislative session; a summary of pending relevant legislation; the name and telephone number of legislative and state agency contacts; and the full text of all bills identified

  9. Selective Electrocatalytic Activity of Ligand Stabilized Copper Oxide Nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Kauffman, Douglas R; Ohodnicki, Paul R; Kail, Brian W; Matranga, Christopher

    2011-01-01

    Ligand stabilization can influence the surface chemistry of Cu oxide nanoparticles (NPs) and provide unique product distributions for electrocatalytic methanol (MeOH) oxidation and CO{sub 2} reduction reactions. Oleic acid (OA) stabilized Cu{sub 2}O and CuO NPs promote the MeOH oxidation reaction with 88% and 99.97% selective HCOH formation, respectively. Alternatively, CO{sub 2} is the only reaction product detected for bulk Cu oxides and Cu oxide NPs with no ligands or weakly interacting ligands. We also demonstrate that OA stabilized Cu oxide NPs can reduce CO{sub 2} into CO with a {approx}1.7-fold increase in CO/H{sub 2} production ratios compared to bulk Cu oxides. The OA stabilized Cu oxide NPs also show 7.6 and 9.1-fold increases in CO/H{sub 2} production ratios compared to weakly stabilized and non-stabilized Cu oxide NPs, respectively. Our data illustrates that the presence and type of surface ligand can substantially influence the catalytic product selectivity of Cu oxide NPs.

  10. The comparison of abdominal muscle activation on unstable surface according to the different trunk stability exercises

    OpenAIRE

    Lee, Jung-seok; Kim, Da-yeon; Kim, Tae-ho

    2016-01-01

    [Purpose] This study aimed to determine the effect of abdominal muscle activities and the activation ratio related to trunk stabilization to compare the effects between the abdominal drawing-in maneuver and lumbar stabilization exercises on an unstable base of support. [Subjects and Methods] Study subjects were 20 male and 10 female adults in their 20s without lumbar pain, who were equally and randomly assigned to either the abdominal drawing-in maneuver group and the lumbar stabilization exe...

  11. Effect of polyols on the conformational stability and biological activity of a model protein lysozyme.

    Science.gov (United States)

    Singh, Somnath; Singh, Jagdish

    2003-01-01

    The purpose of this study was to investigate the stabilizing action of polyols against various protein degradation mechanisms (eg, aggregation, deamidation, oxidation), using a model protein lysozyme. Differential scanning calorimeter (DSC) was used to measure the thermodynamic parameters, mid point transition temperature and calorimetric enthalpy, in order to evaluate conformational stability. Enzyme activity assay was used to corroborate the DSC results. Mannitol, sucrose, lactose, glycerol, and propylene glycol were used as polyols to stabilize lysozyme against aggregation, deamidation, and oxidation. Mannitol was found to stabilize lysozyme against aggregation, sucrose against deamidation both at neutral pH and at acidic pH, and lactose against oxidation. Stabilizers that provided greater conformational stability of lysozyme against various degradation mechanisms also protected specific enzyme activity to a greater extent. It was concluded that DSC and bioassay could be valuable tools for screening stabilizers in protein formulations.

  12. Remedial Action Plan and site design for stabilization of the inactive uranium mill tailings site at Gunnison, Colorado

    International Nuclear Information System (INIS)

    1992-10-01

    Diffusion coefficients for radon gas in earthen materials are required to design suitable radon-barrier covers for uranium tailings impoundments and other materials that emit radon gas. Many early measurements of radon diffusion coefficients relied on the differences in steady-state radon fluxes measured from radon source before and after installation of a cover layer of the material being tested. More recent measurements have utilized the small-sample transient (SST) technique for greater control on moistures and densities of the test soils, greater measurement precision, and reduced testing time and costs. Several of the project sites for the US Department of Energy's Uranium Mill Tailings Remedial Action (UMTRA) Program contain radiologically contaminated subsurface material composed predominantly of cobbles, gravels andsands. Since remedial action designs require radon diffusion coefficients for the source materials as well as the cover materials, these cobbly and gravelly materials also must be tested. This report contains the following information: a description of the test materials used and the methods developed to conduct the SST radon diffusion measurements on cobbly soils; the protocol for conducting radon diffusion tests oncobbly soils; the results of measurements on the test samples; and modifications to the FITS computer code for analyzing the time-dependent radon diffusion data

  13. Remarkable enhancement of O₂ activation on yttrium-stabilized zirconia surface in a dual catalyst bed.

    Science.gov (United States)

    Richard, Mélissandre; Can, Fabien; Duprez, Daniel; Gil, Sonia; Giroir-Fendler, Anne; Bion, Nicolas

    2014-10-13

    Yttrium-stabilized zirconia (YSZ) has been extensively studied as an electrolyte material for solid oxide fuel cells (SOFC) but its performance in heterogeneous catalysis is also the object of a growing number of publications. In both applications, oxygen activation on the YSZ surface remains the step that hinders utilization at moderate temperature. It was demonstrated by oxygen isotope exchange that a dual catalyst bed system consisting of two successive LaMnO3 and YSZ beds without intimate contact drastically enhances oxygen activation on the YSZ surface at 698 K. It can be concluded that LaMnO3 activates the triplet ground-state of molecular oxygen into a low-lying singlet state, thereby facilitating the activation of the O2 molecule on the YSZ oxygen vacancy sites. This phenomenon is shown to improve the catalytic activity of the LaMnO3-Pd/YSZ system for the partial oxidation of methane. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  14. An active damper for stabilizing power electronics-based AC systems

    DEFF Research Database (Denmark)

    Wang, Xiongfei; Blaabjerg, Frede; Liserre, Marco

    2013-01-01

    The mutual interactions between the parallel grid-connected converters coupled through the grid impedance tend to result in a number of stability and power quality challenges. To address them, this paper proposes an active damper concept based on a low-power, high-bandwidth power converter......-connected converters are carried out. The results validate the stabilizing performance of the active damper....

  15. Evaluation of the geologic relations and seismotectonic stability of the Yucca Mountain Area Nevada Nuclear Waste Site Investigations (NNWSI). Progress report, October 1, 1991--September 30, 1992

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1992-09-30

    This report dated 30 September 1992 provides a summary of progress for the project {open_quotes}Evaluation of the Geologic Relations and Seismotectonic Stability of the Yucca Mountain Area, Nevada Nuclear Waste Site Investigation (NNWSI){close_quotes}. This progress report was preceded by the progress report for the year from 1 October 1990 to 30 September 1991. This report summarizes the geologic and seismotectonic studies conducted at Yucca Mountain during the contract period including Quaternary tectonics, an evaluation of mineral resource potential of the area, caldera geology, and volcano-tectonic activity at and near the site. A report of basinal studies conducted during the contract period is also included. Selected papers are indexed separately for inclusion in the Energy Science and Technology Database.

  16. Evaluation of the geologic relations and seismotectonic stability of the Yucca Mountain Area Nevada Nuclear Waste Site Investigation (NNWSI). Progress report, 30 September 1994

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1994-12-31

    This report dated 30 September 1994 provides a summary of progress for the project {open_quotes}Evaluation of the Geologic Relations and Seismotectonic Stability of the Yucca Mountain Area, Nevada Nuclear Waste Site Investigation (NNWSI){close_quotes}. This progress report was preceded by the progress report for the year from 1 October 1992 to 30 September 1993. This report summarizes the geologic and seismotectonic studies conducted at Yucca Mountain during the contract period including Quaternary tectonics, an evaluation of mineral resource potential of the area, caldera geology, and volcano-tectonic activity at and near the site. A report of basinal studies conducted during the contract period is also included. Selected papers are indexed separately for inclusion in the Energy Science and Technology Database.

  17. Two tandem RNase III cleavage sites determine betT mRNA stability in response to osmotic stress in Escherichia coli.

    Directory of Open Access Journals (Sweden)

    Minji Sim

    Full Text Available While identifying genes regulated by ribonuclease III (RNase III in Escherichia coli, we observed that steady-state levels of betT mRNA, which encodes a transporter mediating the influx of choline, are dependent on cellular concentrations of RNase III. In the present study, we also observed that steady-state levels of betT mRNA are dependent on RNase III activity upon exposure to osmotic stress, indicating the presence of cis-acting elements controlled by RNase III in betT mRNA. Primer extension analyses of betT mRNA revealed two tandem RNase III cleavage sites in its stem-loop region, which were biochemically confirmed via in vitro cleavage assays. Analyses of cleavage sites suggested the stochastic selection of cleavage sites by RNase III, and mutational analyses indicated that RNase III cleavage at either site individually is insufficient for efficient betT mRNA degradation. In addition, both the half-life and abundance of betT mRNA were significantly increased in association with decreased RNase III activity under hyper-osmotic stress conditions. Our findings demonstrate that betT mRNA stability is controlled by RNase III at the post-transcriptional level under conditions of osmotic stress.

  18. Active and passive stabilization of n  =  0 RWMs in future tokamak devices

    Science.gov (United States)

    Portone, A.

    2017-12-01

    The aim of this paper is to study the effects of the plasma aspect ratio, plasma elongation and plasma-wall distance on passive stabilization; this will be quantified by the plasma stability margin and instability growth time. Following this first step, the key aspects and figures of merit of plasma active vertical stabilization will be reviewed, with specific emphasis on the maximum disturbances that can be recovered by the plasma control system while minimizing active currents and voltages. Out of the (ex) vessel, optimally placed stabilization coils will be considered. The final goal being the study of the interplay among plasma elongation and the parameters described above to achieve robust passive and active stabilization. By fixing the maximum control voltage, the optimal position of the active coils is derived by estimating the maximum stabilizable vertical displacement and the envelope of current-power requirements for the active control system.

  19. Novel active stabilization technology in highly crosslinked UHMWPEs for superior stability

    Science.gov (United States)

    Oral, Ebru; Neils, Andrew L.; Wannomae, Keith K.; Muratoglu, Orhun K.

    2014-12-01

    Radiation cross-linked ultrahigh molecular weight polyethylene (UHMWPE) is the bearing of choice in joint arthroplasty. The demands on the longevity of this polymer are likely to increase with the recently advancing deterioration of the performance of alternative metal-on-metal implants. Vitamin E-stabilized, cross-linked UHMWPEs are considered the next generation of improved UHMWPE bearing surfaces for improving the oxidation resistance of the polymer. It was recently discovered that in the absence of radiation-induced free radicals, lipids absorbed into UHMWPE from the synovial fluid can initiate oxidation and result in new free radical-mediated oxidation mechanisms. In the presence of radiation-induced free radicals, it is possible for the polymer to oxidize through both existing free radicals at the time of implantation and through newly formed free radicals in vivo. Thus, we showed that reducing the radiation-induced free radicals in vitamin E-stabilized UHMWPE would increase its oxidative stability and presumably lead to improved longevity. We describe mechanical annealing and warm irradiation of irradiated vitamin E blends as novel methods to eliminate 99% of radiation-induced free radicals without sacrificing crystallinity. These are significant improvements in the processing of highly cross-linked UHMWPE for joint implants with improved longevity.

  20. Active stabilization of a diode laser injection lock

    Energy Technology Data Exchange (ETDEWEB)

    Saxberg, Brendan; Plotkin-Swing, Benjamin; Gupta, Subhadeep [Department of Physics, University of Washington, P.O. Box 351560, Seattle, Washington 98195-1560 (United States)

    2016-06-15

    We report on a device to electronically stabilize the optical injection lock of a semiconductor diode laser. Our technique uses as discriminator the peak height of the laser’s transmission signal on a scanning Fabry-Perot cavity and feeds back to the diode current, thereby maintaining maximum optical power in the injected mode. A two-component feedback algorithm provides constant optimization of the injection lock, keeping it robust to slow thermal drifts and allowing fast recovery from sudden failures such as temporary occlusion of the injection beam. We demonstrate the successful performance of our stabilization method in a diode laser setup at 399 nm used for laser cooling of Yb atoms. The device eases the requirements on passive stabilization and can benefit any diode laser injection lock application, particularly those where several such locks are employed.

  1. Active stabilization of a diode laser injection lock.

    Science.gov (United States)

    Saxberg, Brendan; Plotkin-Swing, Benjamin; Gupta, Subhadeep

    2016-06-01

    We report on a device to electronically stabilize the optical injection lock of a semiconductor diode laser. Our technique uses as discriminator the peak height of the laser's transmission signal on a scanning Fabry-Perot cavity and feeds back to the diode current, thereby maintaining maximum optical power in the injected mode. A two-component feedback algorithm provides constant optimization of the injection lock, keeping it robust to slow thermal drifts and allowing fast recovery from sudden failures such as temporary occlusion of the injection beam. We demonstrate the successful performance of our stabilization method in a diode laser setup at 399 nm used for laser cooling of Yb atoms. The device eases the requirements on passive stabilization and can benefit any diode laser injection lock application, particularly those where several such locks are employed.

  2. Active stabilization of a diode laser injection lock

    International Nuclear Information System (INIS)

    Saxberg, Brendan; Plotkin-Swing, Benjamin; Gupta, Subhadeep

    2016-01-01

    We report on a device to electronically stabilize the optical injection lock of a semiconductor diode laser. Our technique uses as discriminator the peak height of the laser’s transmission signal on a scanning Fabry-Perot cavity and feeds back to the diode current, thereby maintaining maximum optical power in the injected mode. A two-component feedback algorithm provides constant optimization of the injection lock, keeping it robust to slow thermal drifts and allowing fast recovery from sudden failures such as temporary occlusion of the injection beam. We demonstrate the successful performance of our stabilization method in a diode laser setup at 399 nm used for laser cooling of Yb atoms. The device eases the requirements on passive stabilization and can benefit any diode laser injection lock application, particularly those where several such locks are employed.

  3. Stability and enzyme inhibition activities of au nanoparticles using an aqueous extract of clove as a reducing and stabilizing agent

    International Nuclear Information System (INIS)

    Hameed, A.; Khan, I.; Naz, S.S.; Islam, N.U.

    2014-01-01

    Gold nanoparticles (AuNPs) were synthesized in one pot using aqueous extract of clove buds (CB) to reduce HAuCl/sub 4/ and stabilize gold in its atomic form at room temperature. To determine the potential of gold nanoparticles with clove buds (AuCB) for in vivo applications, the stability of the nanoparticles was explored as a function of temperature, pH and salt concentration. The suspensions were found to be stable for salt concentrations up to 1 mol/L, temperatures of up to 100 degree C and a pH range of 2-13. Our results indicate that CB exhibited comparable activities to standards of urease and carbonic anhydrase, but its conjugation to Au knocks out the enzyme inhibition activity by about two times. In case of xanthine oxidase activity, CB and its gold Au bio-conjugates (AuCB) are found to be absolutely inactive. (author)

  4. Study the active site of flavonoid applying radiation chemistry

    International Nuclear Information System (INIS)

    Wu Jilan; Sun Gang; Zhang Fugen; He Yongke; Li Jiuqiang

    2000-01-01

    Flavonoid are a large and important class of naturally occurring, low molecular weight benzo-γ-pyrone derivatives which are reported to have a myriad of biological activities, but the study on the active sites of flavonoids is still ambiguous. In this paper, rutin, quercetin and baicalin have been selected as model compounds. It is well known that rutin is used in inhibiting arteriosclerosis and baicalin is antibacterial and antiviral. They have similar basic structure, but their medicinal properties are so different, why? As most flavonoids contain carbonyl group, which can capture electron effectively, we predict that flavonoids can capture electron to form radical anion. The formation of anion radical may have influence on the mitochondrial electron transport chain. The difference in the ability of forming anion radical may cause the difference in their medicinal effects. (author)

  5. Study the active site of flavonoid applying radiation chemistry

    Energy Technology Data Exchange (ETDEWEB)

    Wu Jilan; Sun Gang; Zhang Fugen; He Yongke; Li Jiuqiang [Department of Technical Physics, Peking Univ., Beijing (China)

    2000-03-01

    Flavonoid are a large and important class of naturally occurring, low molecular weight benzo-{gamma}-pyrone derivatives which are reported to have a myriad of biological activities, but the study on the active sites of flavonoids is still ambiguous. In this paper, rutin, quercetin and baicalin have been selected as model compounds. It is well known that rutin is used in inhibiting arteriosclerosis and baicalin is antibacterial and antiviral. They have similar basic structure, but their medicinal properties are so different, why? As most flavonoids contain carbonyl group, which can capture electron effectively, we predict that flavonoids can capture electron to form radical anion. The formation of anion radical may have influence on the mitochondrial electron transport chain. The difference in the ability of forming anion radical may cause the difference in their medicinal effects. (author)

  6. Identification of covalent active site inhibitors of dengue virus protease

    Directory of Open Access Journals (Sweden)

    Koh-Stenta X

    2015-12-01

    Full Text Available Xiaoying Koh-Stenta,1 Joma Joy,1 Si Fang Wang,1 Perlyn Zekui Kwek,1 John Liang Kuan Wee,1 Kah Fei Wan,2 Shovanlal Gayen,1 Angela Shuyi Chen,1 CongBao Kang,1 May Ann Lee,1 Anders Poulsen,1 Subhash G Vasudevan,3 Jeffrey Hill,1 Kassoum Nacro11Experimental Therapeutics Centre, Agency for Science, Technology and Research (A*STAR, Singapore; 2Novartis Institute for Tropical Diseases, Singapore; 3Program in Emerging Infectious Diseases, Duke-NUS Graduate Medical School, SingaporeAbstract: Dengue virus (DENV protease is an attractive target for drug development; however, no compounds have reached clinical development to date. In this study, we utilized a potent West Nile virus protease inhibitor of the pyrazole ester derivative class as a chemical starting point for DENV protease drug development. Compound potency and selectivity for DENV protease were improved through structure-guided small molecule optimization, and protease-inhibitor binding interactions were validated biophysically using nuclear magnetic resonance. Our work strongly suggests that this class of compounds inhibits flavivirus protease through targeted covalent modification of active site serine, contrary to an allosteric binding mechanism as previously described.Keywords: flavivirus protease, small molecule optimization, covalent inhibitor, active site binding, pyrazole ester derivatives

  7. Eel calcitonin binding site distribution and antinociceptive activity in rats

    International Nuclear Information System (INIS)

    Guidobono, F.; Netti, C.; Sibilia, V.; Villa, I.; Zamboni, A.; Pecile, A.

    1986-01-01

    The distribution of binding site for [ 125 I]-eel-calcitonin (ECT) to rat central nervous system, studied by an autoradiographic technique, showed concentrations of binding in the diencephalon, the brain stem and the spinal cord. Large accumulations of grains were seen in the hypothalamus, the amygdala, in the fasciculus medialis prosencephali, in the fasciculus longitudinalis medialis, in the ventrolateral part of the periventricular gray matter, in the lemniscus medialis and in the raphe nuclei. The density of grains in the reticular formation and in the nucleus tractus spinalis nervi trigemini was more moderate. In the spinal cord, grains were scattered throughout the dorsal horns. Binding of the ligand was displaced equally by cold ECT and by salmon CT(sCT), indicating that both peptides bind to the same receptors. Human CT was much weaker than sCT in displacing [ 125 I]-ECT binding. The administration of ECT into the brain ventricles of rats dose-dependently induced a significant and long-lasting enhancement of hot-plate latencies comparable with that obtained with sCT. The antinociceptive activity induced by ECT is compatible with the topographical distribution of binding sites for the peptide and is a further indication that fish CTs are active in the mammalian brain

  8. Oculocutaneous albinism type 1: link between mutations, tyrosinase conformational stability, and enzymatic activity.

    Science.gov (United States)

    Dolinska, Monika B; Kus, Nicole J; Farney, S Katie; Wingfield, Paul T; Brooks, Brian P; Sergeev, Yuri V

    2017-01-01

    Oculocutaneous albinism type 1 (OCA1) is an autosomal recessive disorder caused by mutations in the tyrosinase gene. Two subtypes of OCA1 have been described: severe OCA1A with complete absence of tyrosinase activity and less severe OCA1B with residual tyrosinase activity. Here, we characterize the recombinant human tyrosinase intramelanosomal domain and mutant variants, which mimic genetic changes in both subtypes of OCA1 patients. Proteins were prepared using site-directed mutagenesis, expressed in insect larvae, purified by chromatography, and characterized by enzymatic activities, tryptophan fluorescence, and Gibbs free energy changes. The OCA1A mutants showed very low protein expression and protein yield and are enzymatically inactive. Mutants mimicking OCA1B were biochemically similar to the wild type, but exhibited lower specific activities and protein stabilities. The results are consistent with clinical data, which indicates that OCA1A mutations inactivate tyrosinase and result in severe phenotype, while OCA1B mutations partially inactivate tyrosinase and result in OCA1B albinism. Published 2017. This article is a U.S. Government work and is in the public domain in the USA.

  9. Resurvey of site stability quadrilaterals, Otay Mountain and Quincy, California. [San Andreas fault experiment

    Science.gov (United States)

    Scholz, C. H.

    1977-01-01

    Trilateration quadrilaterals established across two faults near the San Andreas Fault Experiment laser/satellite ranging sites were resurveyed after four years. No evidence of significant tectonic motion was found.

  10. Offshore Wind Guidance Document: Oceanography and Sediment Stability (Version 1) Development of a Conceptual Site Model.

    Energy Technology Data Exchange (ETDEWEB)

    Roberts, Jesse D.; Jason Magalen; Craig Jones

    2014-06-01

    This guidance document provide s the reader with an overview of the key environmental considerations for a typical offshore wind coastal location and the tools to help guide the reader through a thoro ugh planning process. It will enable readers to identify the key coastal processes relevant to their offshore wind site and perform pertinent analysis to guide siting and layout design, with the goal of minimizing costs associated with planning, permitting , and long - ter m maintenance. The document highlight s site characterization and assessment techniques for evaluating spatial patterns of sediment dynamics in the vicinity of a wind farm under typical, extreme, and storm conditions. Finally, the document des cribe s the assimilation of all of this information into the conceptual site model (CSM) to aid the decision - making processes.

  11. 3D active stabilization system with sub-micrometer resolution.

    Directory of Open Access Journals (Sweden)

    Olli Kursu

    Full Text Available Stable positioning between a measurement probe and its target from sub- to few micrometer scales has become a prerequisite in precision metrology and in cellular level measurements from biological tissues. Here we present a 3D stabilization system based on an optoelectronic displacement sensor and custom piezo-actuators driven by a feedback control loop that constantly aims to zero the relative movement between the sensor and the target. We used simulations and prototyping to characterize the developed system. Our results show that 95% attenuation of movement artifacts is achieved at 1 Hz with stabilization performance declining to ca. 70% attenuation at 10 Hz. Stabilization bandwidth is limited by mechanical resonances within the displacement sensor that occur at relatively low frequencies, and are attributable to the sensor's high force sensitivity. We successfully used brain derived micromotion trajectories as a demonstration of complex movement stabilization. The micromotion was reduced to a level of ∼1 µm with nearly 100 fold attenuation at the lower frequencies that are typically associated with physiological processes. These results, and possible improvements of the system, are discussed with a focus on possible ways to increase the sensor's force sensitivity without compromising overall system bandwidth.

  12. In vitro antioxidant and membrane stabilization activities of the fruit ...

    African Journals Online (AJOL)

    Arthritis is an inflammation of one or more joints. There is considerable experimental evidence linking lysosomal enzymes with tissue damage in arthritis. This study investigated anti-arthritic properties of Tetrapleura tetraptera (TT) using membrane stabilization assay (MSA). Powdered TT fruit sample was extracted by ...

  13. Mechanisms of antibacterial activity and stability of silver ...

    Indian Academy of Sciences (India)

    2016-08-26

    Aug 26, 2016 ... ... antimicrobial stability and durability. Furthermore, the interdependence between the concentration of released silver and bacterial growth inhibition was demonstrated. In addition, direct contact killing and released silver-mediated killing have been proposed as a bactericidal mechanism of action of tested ...

  14. 3D Active Stabilization System with Sub-Micrometer Resolution

    Science.gov (United States)

    Rahkonen, Timo; Vähäsöyrinki, Mikko

    2012-01-01

    Stable positioning between a measurement probe and its target from sub- to few micrometer scales has become a prerequisite in precision metrology and in cellular level measurements from biological tissues. Here we present a 3D stabilization system based on an optoelectronic displacement sensor and custom piezo-actuators driven by a feedback control loop that constantly aims to zero the relative movement between the sensor and the target. We used simulations and prototyping to characterize the developed system. Our results show that 95 % attenuation of movement artifacts is achieved at 1 Hz with stabilization performance declining to ca. 70 % attenuation at 10 Hz. Stabilization bandwidth is limited by mechanical resonances within the displacement sensor that occur at relatively low frequencies, and are attributable to the sensor's high force sensitivity. We successfully used brain derived micromotion trajectories as a demonstration of complex movement stabilization. The micromotion was reduced to a level of ∼1 µm with nearly 100 fold attenuation at the lower frequencies that are typically associated with physiological processes. These results, and possible improvements of the system, are discussed with a focus on possible ways to increase the sensor's force sensitivity without compromising overall system bandwidth. PMID:22900045

  15. In Situ Probing of the Active Site Geometry of Ultrathin Nanowires for the Oxygen Reduction Reaction.

    Science.gov (United States)

    Liu, Haiqing; An, Wei; Li, Yuanyuan; Frenkel, Anatoly I; Sasaki, Kotaro; Koenigsmann, Christopher; Su, Dong; Anderson, Rachel M; Crooks, Richard M; Adzic, Radoslav R; Liu, Ping; Wong, Stanislaus S

    2015-10-07

    To create truly effective electrocatalysts for the cathodic reaction governing proton exchange membrane fuel cells (PEMFC), namely the oxygen reduction reaction (ORR), necessitates an accurate and detailed structural understanding of these electrocatalysts, especially at the nanoscale, and to precisely correlate that structure with demonstrable performance enhancement. To address this key issue, we have combined and interwoven theoretical calculations with experimental, spectroscopic observations in order to acquire useful structural insights into the active site geometry with implications for designing optimized nanoscale electrocatalysts with rationally predicted properties. Specifically, we have probed ultrathin (∼2 nm) core-shell Pt∼Pd9Au nanowires, which have been previously shown to be excellent candidates for ORR in terms of both activity and long-term stability, from the complementary perspectives of both DFT calculations and X-ray absorption spectroscopy (XAS). The combination and correlation of data from both experimental and theoretical studies has revealed for the first time that the catalytically active structure of our ternary nanowires can actually be ascribed to a PtAu∼Pd configuration, comprising a PtAu binary shell and a pure inner Pd core. Moreover, we have plausibly attributed the resulting structure to a specific synthesis step, namely the Cu underpotential deposition (UPD) followed by galvanic replacement with Pt. Hence, the fundamental insights gained into the performance of our ultrathin nanowires from our demonstrated approach will likely guide future directed efforts aimed at broadly improving upon the durability and stability of nanoscale electrocatalysts in general.

  16. The PINK1 p.I368N mutation affects protein stability and ubiquitin kinase activity.

    Science.gov (United States)

    Ando, Maya; Fiesel, Fabienne C; Hudec, Roman; Caulfield, Thomas R; Ogaki, Kotaro; Górka-Skoczylas, Paulina; Koziorowski, Dariusz; Friedman, Andrzej; Chen, Li; Dawson, Valina L; Dawson, Ted M; Bu, Guojun; Ross, Owen A; Wszolek, Zbigniew K; Springer, Wolfdieter

    2017-04-24

    Mutations in PINK1 and PARKIN are the most common causes of recessive early-onset Parkinson's disease (EOPD). Together, the mitochondrial ubiquitin (Ub) kinase PINK1 and the cytosolic E3 Ub ligase PARKIN direct a complex regulated, sequential mitochondrial quality control. Thereby, damaged mitochondria are identified and targeted to degradation in order to prevent their accumulation and eventually cell death. Homozygous or compound heterozygous loss of either gene function disrupts this protective pathway, though at different steps and by distinct mechanisms. While structure and function of PARKIN variants have been well studied, PINK1 mutations remain poorly characterized, in particular under endogenous conditions. A better understanding of the exact molecular pathogenic mechanisms underlying the pathogenicity is crucial for rational drug design in the future. Here, we characterized the pathogenicity of the PINK1 p.I368N mutation on the clinical and genetic as well as on the structural and functional level in patients' fibroblasts and in cell-based, biochemical assays. Under endogenous conditions, PINK1 p.I368N is expressed, imported, and N-terminally processed in healthy mitochondria similar to PINK1 wild type (WT). Upon mitochondrial damage, however, full-length PINK1 p.I368N is not sufficiently stabilized on the outer mitochondrial membrane (OMM) resulting in loss of mitochondrial quality control. We found that binding of PINK1 p.I368N to the co-chaperone complex HSP90/CDC37 is reduced and stress-induced interaction with TOM40 of the mitochondrial protein import machinery is abolished. Analysis of a structural PINK1 p.I368N model additionally suggested impairments of Ub kinase activity as the ATP-binding pocket was found deformed and the substrate Ub was slightly misaligned within the active site of the kinase. Functional assays confirmed the lack of Ub kinase activity. Here we demonstrated that mutant PINK1 p.I368N can not be stabilized on the OMM upon

  17. Enhancer transcripts mark active estrogen receptor binding sites.

    Science.gov (United States)

    Hah, Nasun; Murakami, Shino; Nagari, Anusha; Danko, Charles G; Kraus, W Lee

    2013-08-01

    We have integrated and analyzed a large number of data sets from a variety of genomic assays using a novel computational pipeline to provide a global view of estrogen receptor 1 (ESR1; a.k.a. ERα) enhancers in MCF-7 human breast cancer cells. Using this approach, we have defined a class of primary transcripts (eRNAs) that are transcribed uni- or bidirectionally from estrogen receptor binding sites (ERBSs) with an average transcription unit length of ∼3-5 kb. The majority are up-regulated by short treatments with estradiol (i.e., 10, 25, or 40 min) with kinetics that precede or match the induction of the target genes. The production of eRNAs at ERBSs is strongly correlated with the enrichment of a number of genomic features that are associated with enhancers (e.g., H3K4me1, H3K27ac, EP300/CREBBP, RNA polymerase II, open chromatin architecture), as well as enhancer looping to target gene promoters. In the absence of eRNA production, strong enrichment of these features is not observed, even though ESR1 binding is evident. We find that flavopiridol, a CDK9 inhibitor that blocks transcription elongation, inhibits eRNA production but does not affect other molecular indicators of enhancer activity, suggesting that eRNA production occurs after the assembly of active enhancers. Finally, we show that an enhancer transcription "signature" based on GRO-seq data can be used for de novo enhancer prediction across cell types. Together, our studies shed new light on the activity of ESR1 at its enhancer sites and provide new insights about enhancer function.

  18. The impact of fluid advection on gas hydrate stability: Investigations at sites of methane seepage offshore Costa Rica

    Science.gov (United States)

    Crutchley, G. J.; Klaeschen, D.; Planert, L.; Bialas, J.; Berndt, C.; Papenberg, C.; Hensen, C.; Hornbach, M. J.; Krastel, S.; Brueckmann, W.

    2014-09-01

    Fluid flow through marine sediments drives a wide range of processes, from gas hydrate formation and dissociation, to seafloor methane seepage including the development of chemosynthetic ecosystems, and ocean acidification. Here, we present new seismic data that reveal the 3D nature of focused fluid flow beneath two mound structures on the seafloor offshore Costa Rica. These mounds have formed as a result of ongoing seepage of methane-rich fluids. We show the spatial impact of advective heat flow on gas hydrate stability due to the channelled ascent of warm fluids towards the seafloor. The base of gas hydrate stability (BGHS) imaged in the seismic data constrains peak heat flow values to ∼60 mW m and ∼70 mW m beneath two separate seep sites known as Mound 11 and Mound 12, respectively. The initiation of pronounced fluid flow towards these structures was likely controlled by fault networks that acted as efficient pathways for warm fluids ascending from depth. Through the gas hydrate stability zone, fluid flow has been focused through vertical conduits that we suggest developed as migrating fluids generated their own secondary permeability by fracturing strata as they forced their way upwards towards the seafloor. We show that Mound 11 and Mound 12 (about 1 km apart on the seafloor) are sustained by independent fluid flow systems through the hydrate system, and that fluid flow rates across the BGHS are probably similar beneath both mounds. 2D seismic data suggest that these two flow systems might merge at approximately 1 km depth, i.e. much deeper than the BGHS. This study provides a new level of detail and understanding of how channelled, anomalously-high fluid flow towards the seafloor influences gas hydrate stability. Thus, gas hydrate systems have good potential for quantifying the upward flow of subduction system fluids to seafloor seep sites, since the fluids have to interact with and leave their mark on the hydrate system before reaching the seafloor.

  19. Biochemical characterization of mutants in the active site residues of the β-galactosidase enzyme of Bacillus circulans ATCC 31382

    Directory of Open Access Journals (Sweden)

    Jelle B. Bultema

    2014-01-01

    Full Text Available The Bacillus circulans ATCC 31382 β-galactosidase (BgaD is a retaining-type glycosidase of glycoside hydrolase family 2 (GH2. Its commercial enzyme preparation, Biolacta N5, is used for commercial-scale production of galacto-oligosaccharides (GOS. The BgaD active site and catalytic amino acid residues have not been studied. Using bioinformatic routines we identified two putative catalytic glutamates and two highly conserved active site histidines. The site-directed mutants E447N, E532Q, and H345F, H379F had lost (almost all catalytic activity. This confirmed their essential role in catalysis, as general acid/base catalyst (E447 and nucleophile (E532, and as transition state stabilizers (H345, H379, respectively.

  20. DAC-3 Pointing Stability Analysis Results for SAGE 3 and Other Users of the International Space Station (ISS) Payload Attachment Sites (PAS)

    Science.gov (United States)

    Woods-Vedeler, Jessica A.; Rombado, Gabriel

    1997-01-01

    The purpose of this paper is to provide final results of a pointing stability analysis for external payload attachment sites (PAS) on the International Space Station (ISS). As a specific example, the pointing stability requirement of the SAGE III atmospheric science instrument was examined in this paper. The instrument requires 10 arcsec stability over 2 second periods. SAGE 3 will be mounted on the ISS starboard side at the lower, outboard FIAS. In this engineering analysis, an open-loop DAC-3 finite element model of ISS was used by the Microgravity Group at Johnson Space Flight Center to generate transient responses at PAS to a limited number of disturbances. The model included dynamics up to 50 Hz. Disturbance models considered included operation of the solar array rotary joints, thermal radiator rotary joints, and control moment gyros. Responses were filtered to model the anticipated vibration attenuation effects of active control systems on the solar and thermal radiator rotary joints. A pointing stability analysis was conducted by double integrating acceleration transient over a 2 second period. Results of the analysis are tabulated for ISS X, Y, and Z Axis rotations. These results indicate that the largest excursions in rotation during pointing occurred due to rapid slewing of the thermal radiator. Even without attenuation at the rotary joints, the resulting pointing error was limited to less than 1.6 arcsec. With vibration control at the joints, to a maximum 0.5 arcsec over a 2 second period. Based on this current level of model definition, it was concluded that between 0 - 50 Hz, the pointing stability requirement for SAGE 3 will not be exceeded by the disturbances evaluated in this study.

  1. Distinct Roles of N- and O-Glycans in Cellulase Activity and Stability

    Energy Technology Data Exchange (ETDEWEB)

    Beckham, Gregg T [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Amore, Antonella [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Knott, Brandon C [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Linger, Jeffrey G [National Renewable Energy Laboratory (NREL), Golden, CO (United States); VanderWall, Todd A [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Shollenberger, Todd S [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Yarbrough, John M [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Crowley, Michael F [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Himmel, Michael E [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Decker, Steve [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Hobdey, Sarah E. [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Taylor III, Larry E. [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Supekar, Nitin T. [University of Georgia; Shajahan, Asif [University of Georgia; Azadi, Parastoo [University of Georgia; Zhao, Peng [University of Georgia; Wells, Lance [University of Georgia; Tan, Zhongping [University of Colorado

    2017-12-11

    In nature, many microbes secrete mixtures of glycoside hydrolases, oxidoreductases, and accessory enzymes to deconstruct polysaccharides and lignin in plants. These enzymes are often decorated with N- and O-glycosylation, the roles of which have been broadly attributed to protection from proteolysis, as the extracellular milieu is an aggressive environment. Glycosylation has been shown to sometimes affect activity, but these effects are not fully understood. Here, we examine N- and O-glycosylation on a model, multimodular glycoside hydrolase family 7 cellobiohydrolase (Cel7A), which exhibits an O-glycosylated carbohydrate-binding module (CBM) and an O-glycosylated linker connected to an N- and O-glycosylated catalytic domain (CD) - a domain architecture common to many biomass-degrading enzymes. We report consensus maps for Cel7A glycosylation that include glycan sites and motifs. Additionally, we examine the roles of glycans on activity, substrate binding, and thermal and proteolytic stability. N-glycan knockouts on the CD demonstrate that N-glycosylation has little impact on cellulose conversion or binding, but does have major stability impacts. O-glycans on the CBM have little impact on binding, proteolysis, or activity in the whole-enzyme context. However, linker O-glycans greatly impact cellulose conversion via their contribution to proteolysis resistance. Molecular simulations predict an additional role for linker O-glycans, namely that they are responsible for maintaining separation between ordered domains when Cel7A is engaged on cellulose, as models predict a-helix formation and decreased cellulose interaction for the nonglycosylated linker. Overall, this study reveals key roles for N- and O-glycosylation that are likely broadly applicable to other plant cell-wall-degrading enzymes.

  2. Role of the NC-loop in catalytic activity and stability in lipase from Fervidobacterium changbaicum.

    Directory of Open Access Journals (Sweden)

    Binchun Li

    Full Text Available Flexible NC-loops between the catalytic domain and the cap domain of the α/β hydrolase fold enzymes show remarkable diversity in length, sequence, and configuration. Recent investigations have suggested that the NC-loop might be involved in catalysis and substrate recognition in many enzymes from the α/β hydrolase fold superfamily. To foster a deep understanding of its role in catalysis, stability, and divergent evolution, we here systemically investigated the function of the NC-loop (residues 131-151 in a lipase (FClip1 from thermophilic bacterium Fervidobacterium changbaicum by loop deletion, alanine-scanning mutagenesis and site-directed mutagenesis. We found that the upper part of the NC-loop (residues 131-138 was of great importance to enzyme catalysis. Single substitutions in this region could fine-tune the activity of FClip1 as much as 41-fold, and any deletions from this region rendered the enzyme completely inactive. The lower part of the NC-loop (residues 139-151 was capable of enduring extensive deletions without loss of activity. The shortened mutants in this region were found to show both improved activity and increased stability simultaneously. We therefore speculated that the NC-loop, especially the lower part, would be a perfect target for enzyme engineering to optimize the enzymatic properties, and might present a hot zone for the divergent evolution of α/β hydrolases. Our findings may provide an opportunity for better understanding of the mechanism of divergent evolution in the α/β hydrolase fold superfamily, and may also guide the design of novel biocatalysts for industrial applications.

  3. Metal active site elasticity linked to activation of homocysteine in methionine synthases

    Energy Technology Data Exchange (ETDEWEB)

    Koutmos, Markos; Pejchal, Robert; Bomer, Theresa M.; Matthews, Rowena G.; Smith, Janet L.; Ludwig, Martha L. (Michigan)

    2008-04-02

    Enzymes possessing catalytic zinc centers perform a variety of fundamental processes in nature, including methyl transfer to thiols. Cobalamin-independent (MetE) and cobalamin-dependent (MetH) methionine synthases are two such enzyme families. Although they perform the same net reaction, transfer of a methyl group from methyltetrahydrofolate to homocysteine (Hcy) to form methionine, they display markedly different catalytic strategies, modular organization, and active site zinc centers. Here we report crystal structures of zinc-replete MetE and MetH, both in the presence and absence of Hcy. Structural investigation of the catalytic zinc sites of these two methyltransferases reveals an unexpected inversion of zinc geometry upon binding of Hcy and displacement of an endogenous ligand in both enzymes. In both cases a significant movement of the zinc relative to the protein scaffold accompanies inversion. These structures provide new information on the activation of thiols by zinc-containing enzymes and have led us to propose a paradigm for the mechanism of action of the catalytic zinc sites in these and related methyltransferases. Specifically, zinc is mobile in the active sites of MetE and MetH, and its dynamic nature helps facilitate the active site conformational changes necessary for thiol activation and methyl transfer.

  4. Differential active site loop conformations mediate promiscuous activities in the lactonase SsoPox.

    Directory of Open Access Journals (Sweden)

    Julien Hiblot

    Full Text Available Enzymes are proficient catalysts that enable fast rates of Michaelis-complex formation, the chemical step and products release. These different steps may require different conformational states of the active site that have distinct binding properties. Moreover, the conformational flexibility of the active site mediates alternative, promiscuous functions. Here we focused on the lactonase SsoPox from Sulfolobus solfataricus. SsoPox is a native lactonase endowed with promiscuous phosphotriesterase activity. We identified a position in the active site loop (W263 that governs its flexibility, and thereby affects the substrate specificity of the enzyme. We isolated two different sets of substitutions at position 263 that induce two distinct conformational sampling of the active loop and characterized the structural and kinetic effects of these substitutions. These sets of mutations selectively and distinctly mediate the improvement of the promiscuous phosphotriesterase and oxo-lactonase activities of SsoPox by increasing active-site loop flexibility. These observations corroborate the idea that conformational diversity governs enzymatic promiscuity and is a key feature of protein evolvability.

  5. Evaluation of the geologic relations and seismotectonic stability of the Yucca Mountain area, Nevada Nuclear Waste Site Investigation (NNWSI)

    International Nuclear Information System (INIS)

    1988-10-01

    This report provides a summary of progress for the project ''Evaluation of the Geologic Relations and Seismotectonic Stability of the Yucca Mountain Area, Nevada Nuclear Waste Site Investigation (NNWSI)'' for the eighteen month period of January 1, 1987 to June 10, 1988. This final report was preceded by the final report for the initial six month period, July 1, 1986 to December 31, 1986 (submitted on January 25, 1987, and revised in June 1987.) Quaternary Tectonics, Geochemical, Mineral Deposits, Vulcanic Geology, Seismology, Tectonics, Neotectonics, Remote Sensing, Geotechnical Assessments, Geotechnical Rock Mass Assessments, Basinal Studies, and Strong Ground Motion

  6. Stability in Bank Income through Fee-based Activities

    Directory of Open Access Journals (Sweden)

    R. K. Uppal

    2010-12-01

    Full Text Available This paper is an attempt to study the trends in non-interest income which is a vital source of stability in bank income. For this, the study takes some parameters like interest and non-interest income as a percentage to total income, share of non-interest income components like exchange & brokerage, sale in investment and exchange transaction. On the basis of these parameters the study concludes that interest income is continuously declining due to deregulation in interest rates and non-interest income is rising. Among the non-interest income components, commodity exchange & brokerage witnessed a large share while exchange transaction witnessed a meager part. The paper also gives some ways and means to bring stability in the total income.

  7. Evaluation of the geologic relations and seismotectonic stability of the Yucca Mountain Area, Nevada Nuclear Waste Site Investigation (NNWSI)

    International Nuclear Information System (INIS)

    Peppin, W.A.

    1988-01-01

    This document describes activities for the year ending 30 June 1988 by staff members of the Seismological Laboratory in support of the Yucca Mountain site assessment program. Activities during the year centered largely around acquisition of equipment to be used for site assessment and around a review of the draft site characterization plan for Yucca Mountain. Due to modifications in the scheduling and level of funding, this work has not progressed as originally anticipated. The report describes progress in seven areas, listed in approximate order of significance to the Yucca Mountain project. These are: (1) equipment acquisition, (2) review of the draft site characterization plan, (3) studies of earthquake sequence related to the tectonic problems at Yucca Mountain, (4) a review of the work of Szymanski in relation to Task 4 concerns, (5) coordination meetings with USGS, DOE, and NRC personnel, (6) studies related to Yucca Mountain, and (7) other studies

  8. Revegetation and rock cover for stabilization of inactive uranium mill tailings disposal sites. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Beedlow, P.A.

    1984-05-01

    Guidelines for using vegetation and rock to protect inactive uranium mill tailings from erosion were developed by Pacific Northwest Laboratory as part of the Department of Energy's Uranium Mill Tailings Remedial Action Project (UMTRAP) Technology Development program. Information on soils, climate, and vegetation were collected for 20 inactive tailings sites in the western United States. Sites were grouped according to similarities in climate and vegetation. Soil loss for those sites was characterized using the Universal Soil Loss Equation. Test plots were used to evaluate (1) the interaction between vegetation and sealant barrier systems and (2) the effects of surface rock on soil water and vegetation. Lysimeter and simulation studies were used to direct and support field experiments. 49 references, 17 figures, 16 tables.

  9. Revegetation and rock cover for stabilization of inactive uranium mill tailings disposal sites. Final report

    International Nuclear Information System (INIS)

    Beedlow, P.A.

    1984-05-01

    Guidelines for using vegetation and rock to protect inactive uranium mill tailings from erosion were developed by Pacific Northwest Laboratory as part of the Department of Energy's Uranium Mill Tailings Remedial Action Project (UMTRAP) Technology Development program. Information on soils, climate, and vegetation were collected for 20 inactive tailings sites in the western United States. Sites were grouped according to similarities in climate and vegetation. Soil loss for those sites was characterized using the Universal Soil Loss Equation. Test plots were used to evaluate (1) the interaction between vegetation and sealant barrier systems and (2) the effects of surface rock on soil water and vegetation. Lysimeter and simulation studies were used to direct and support field experiments. 49 references, 17 figures, 16 tables

  10. Active Stabilization of a Diode Laser Injection Lock

    OpenAIRE

    Saxberg, Brendan; Plotkin-Swing, Benjamin; Gupta, Subhadeep

    2016-01-01

    We report on a device to electronically stabilize the optical injection lock of a semiconductor diode laser. Our technique uses as discriminator the peak height of the laser's transmission signal on a scanning Fabry-Perot cavity and feeds back to the diode current, thereby maintaining maximum optical power in the injected mode. A two-component feedback algorithm provides constant optimization of the injection lock, keeping it robust to slow thermal drifts and allowing fast recovery from sudde...

  11. Stability Simulation of a Vehicle with Wheel Active Steering

    Directory of Open Access Journals (Sweden)

    Brabec Pavel

    2016-01-01

    Full Text Available This paper deals with the possibility of increasing the vehicle driving stability at a higher speed. One of the ways how to achieve higher stability is using the 4WS system. Mathematical description of vehicle general movement is a very complex task. For simulation, models which are aptly simplified are used. For the first approach, so-called single-truck vehicle model (often linear is usually used. For the simulation, we have chosen to extend the model into a two-truck one, which includes the possibility to input more vehicle parameters. Considering the 4WS system, it is possible to use a number of potential regulations. In our simulation model, the regulation system with compound coupling was used. This type of regulation turns the rear wheels depending on the input parameters of the system (steering angle of the front wheels and depending on the output moving quantities of the vehicle, most frequently the yaw rate. Criterion for compensation of lateral deflection centre of gravity angle is its zero value, or more precisely the zero value of its first-order derivative. Parameters and set-up of the simulation model were done in conjunction with the dSAPACE software. Reference performances of the vehicle simulation model were made through the defined manoeuvres. But the simulation results indicate that the rear-wheels steering can have a positive effect on the vehicle movement stability, especially when changing the driving direction at high speed.

  12. Stability of thin liquid films containing surface active particles

    Science.gov (United States)

    Umashankar, Hariharan; Kalpathy, Sreeram; Dixit, Harish

    2017-11-01

    The stability and dynamics of thin liquid films(industrial settings like coating and printing processes and extraction of oil from porous rocks. In this study a hydrodynamic model is introduced to capture the long term evolution of a Newtonian liquid film containing insoluble surfaceactive particles.We consider here the possibility of four distinct interaction regimes based on the surface rheological effects of the particles, such that either, both or neither of Marangoni and surface viscosity effects would be present at the leading order in the governing equations. The liquid film is bounded by a rigid impermeable solid below and covered by passive air phase above.A standard linear stability analysis and nonlinear simulations are performed on the set of highly coupled partial differential evolution equations. Linear stability analysis gives insights on whether a particular imposed perturbationwavenumber will grow or decay in time and also evaluating the fastest growing wavenumber. Parametric studies for all four regimes provides a strong confirmation that surface viscosity and Marangoni effects are indeed rupture delaying effects.

  13. Implementation of an ex situ stabilization technique at the Sand Springs superfund site to solidify and stabilize acid tar sludges involving a quick-lime based stabilization process and innovative equipment design

    International Nuclear Information System (INIS)

    McManus, R.W.; Grajczak, P.; Wilcoxson, J.C.; Webster, S.D.

    1997-01-01

    An old refinery site was safely remediated a year before schedule and for 25% less than final engineering estimates for the stabilization remedy thanks to energetic project management and innovative design involving ex situ stabilization/solidification of acid tar sludges. A quicklime based process, Dispersion by Chemical Reaction (DCR trademark), was employed to solidify and stabilize (SS) over 103,000 cubic meters (135,000 cubic yards) of petroleum waste, mostly acidic tarry sludge. The SS process was selected over competing methods because it afforded minimal volume increase, could readily achieve Record of Decision (ROD) specified physical and chemical treatment goals, could be implemented with treatment equipment that minimized emissions, and could be performed with low reagent usage and at low cost. To ensure treatment goals were achieved and an accelerated schedule met, a custom designed and fabricated transportable treatment unit (TTU) was employed to implement the process. The treated material was visually soil-like in character, it was left in stockpiles for periods of time, and it was placed and compacted in the on site landfill using standard earth-moving equipment

  14. Abdominal muscle activation increases lumbar spinal stability: analysis of contributions of different muscle groups.

    Science.gov (United States)

    Stokes, Ian A F; Gardner-Morse, Mack G; Henry, Sharon M

    2011-10-01

    Antagonistic activation of abdominal muscles and increased intra-abdominal pressure are associated with both spinal unloading and spinal stabilization. Rehabilitation regimens have been proposed to improve spinal stability via selective recruitment of certain trunk muscle groups. This biomechanical analytical study addressed whether lumbar spinal stability is increased by such selective activation. The biomechanical model included anatomically realistic three-layers of curved abdominal musculature, rectus abdominis and 77 symmetrical pairs of dorsal muscles. The muscle activations were calculated with the model loaded with either flexion, extension, lateral bending or axial rotation moments up to 60 Nm, along with intra-abdominal pressure up to 5 or 10 kPa (37.5 or 75 mm Hg) and partial bodyweight. After solving for muscle forces, a buckling analysis quantified spinal stability. Subsequently, different patterns of muscle activation were studied by forcing activation of selected abdominal muscles to at least 10% or 20% of maximum. Spinal stability increased by an average factor of 1.8 with doubling of intra-abdominal pressure. Forcing at least 10% activation of obliques or transversus abdominis muscles increased stability slightly for efforts other than flexion, but forcing at least 20% activation generally did not produce further increase in stability. Forced activation of rectus abdominis did not increase stability. Based on analytical predictions, the degree of stability was not substantially influenced by selective forcing of muscle activation. This casts doubt on the supposed mechanism of action of specific abdominal muscle exercise regimens that have been proposed for low back pain rehabilitation. Copyright © 2011 Elsevier Ltd. All rights reserved.

  15. Metals in the active site of native protein phosphatase-1.

    Science.gov (United States)

    Heroes, Ewald; Rip, Jens; Beullens, Monique; Van Meervelt, Luc; De Gendt, Stefan; Bollen, Mathieu

    2015-08-01

    Protein phosphatase-1 (PP1) is a major protein Ser/Thr phosphatase in eukaryotic cells. Its activity depends on two metal ions in the catalytic site, which were identified as manganese in the bacterially expressed phosphatase. However, the identity of the metal ions in native PP1 is unknown. In this study, total reflection X-ray fluorescence (TXRF) was used to detect iron and zinc in PP1 that was purified from rabbit skeletal muscle. Metal exchange experiments confirmed that the distinct substrate specificity of recombinant and native PP1 is determined by the nature of their associated metals. We also found that the iron level associated with native PP1 is decreased by incubation with inhibitor-2, consistent with a function of inhibitor-2 as a PP1 chaperone. Copyright © 2015 Elsevier Inc. All rights reserved.

  16. Troponin C Mutations Partially Stabilize the Active State of Regulated Actin and Fully Stabilize the Active State When Paired with Δ14 TnT.

    Science.gov (United States)

    Baxley, Tamatha; Johnson, Dylan; Pinto, Jose R; Chalovich, Joseph M

    2017-06-13

    Striated muscle contraction is regulated by the actin-associated proteins tropomyosin and troponin. The extent of activation of myosin ATPase activity is lowest in the absence of both Ca 2+ and activating cross-bridges (i.e., S1-ADP or rigor S1). Binding of activating species of myosin to actin at a saturating Ca 2+ concentration stabilizes the most active state (M state) of the actin-tropomyosin-troponin complex (regulated actin). Ca 2+ binding alone produces partial stabilization of the active state. The extent of stabilization at a saturating Ca 2+ concentration depends on the isoform of the troponin subunits, the phosphorylation state of troponin, and, in the case of cardiac muscle, the presence of hypertrophic cardiomyopathy-producing mutants of troponin T and troponin I. Cardiac dysfunction is also associated with mutations of troponin C (TnC). Troponin C mutants A8V, C84Y, and D145E increase the Ca 2+ sensitivity of ATPase activity. We show that these mutants change the distribution of regulated actin states. The A8V and C84Y TnC mutants decreased the inactive B state distribution slightly at low Ca 2+ concentrations, but the D145E mutants had no effect on that state. All TnC mutants increased the level of the active M state compared to that of the wild type, at a saturating Ca 2+ concentration. Troponin complexes that contained two mutations that stabilize the active M state, A8V TnC and Δ14 TnT, appeared to be completely in the active state in the presence of only Ca 2+ . Because Ca 2+ gives full activation, in this situation, troponin must be capable of positioning tropomyosin in the active M state without the need for rigor myosin binding.

  17. Depletion of GGA3 stabilizes BACE and enhances beta-secretase activity.

    Science.gov (United States)

    Tesco, Giuseppina; Koh, Young Ho; Kang, Eugene L; Cameron, Andrew N; Das, Shinjita; Sena-Esteves, Miguel; Hiltunen, Mikko; Yang, Shao-Hua; Zhong, Zhenyu; Shen, Yong; Simpkins, James W; Tanzi, Rudolph E

    2007-06-07

    Beta-site APP-cleaving enzyme (BACE) is required for production of the Alzheimer's disease (AD)-associated Abeta protein. BACE levels are elevated in AD brain, and increasing evidence reveals BACE as a stress-related protease that is upregulated following cerebral ischemia. However, the molecular mechanism responsible is unknown. We show that increases in BACE and beta-secretase activity are due to posttranslational stabilization following caspase activation. We also found that during cerebral ischemia, levels of GGA3, an adaptor protein involved in BACE trafficking, are reduced, while BACE levels are increased. RNAi silencing of GGA3 also elevated levels of BACE and Abeta. Finally, in AD brain samples, GGA3 protein levels were significantly decreased and inversely correlated with increased levels of BACE. In summary, we have elucidated a GGA3-dependent mechanism regulating BACE levels and beta-secretase activity. This mechanism may explain increased cerebral levels of BACE and Abeta following cerebral ischemia and existing in AD.

  18. Depletion of GGA3 stabilizes BACE and enhances β-secretase activity

    Science.gov (United States)

    Tesco, Giuseppina; Koh, Young Ho; Kang, Eugene; Cameron, Andrew; Das, Shinjita; Sena-Esteves, Miguel; Hiltunen, Mikko; Yang, Shao-Hua; Zhong, Zhenyu; Shen, Yong; Simpkins, James; Tanzi, Rudolph E.

    2007-01-01

    Summary Beta-site APP-cleaving enzyme (BACE) is required for production of the Alzheimer's disease (AD)-associated Aβ protein. BACE levels are elevated in AD brain, and increasing evidence reveals BACE as a stress-related protease that is upregulated following cerebral ischemia. However, the molecular mechanism responsible is unknown. We show that increases in BACE and β-secretase activity are due to post-translational stabilization following caspase activation. We also found that during cerebral ischemia, levels of GGA3, an adaptor protein involved in BACE trafficking, are reduced, while BACE levels are increased. RNAi silencing of GGA3 also elevated levels of BACE and Aβ. Finally, in AD brain samples, GGA3 protein levels were significantly decreased and inversely correlated with increased levels of BACE. In summary, we have elucidated a novel GGA3-dependent mechanism regulating BACE levels and β-secretase activity. This mechanism may explain increased cerebral levels of BACE and Aβ following cerebral ischemia and in AD. PMID:17553422

  19. Active site loop conformation regulates promiscuous activity in a lactonase from Geobacillus kaustophilus HTA426.

    Directory of Open Access Journals (Sweden)

    Yu Zhang

    Full Text Available Enzyme promiscuity is a prerequisite for fast divergent evolution of biocatalysts. A phosphotriesterase-like lactonase (PLL from Geobacillus kaustophilus HTA426 (GkaP exhibits main lactonase and promiscuous phosphotriesterase activities. To understand its catalytic and evolutionary mechanisms, we investigated a "hot spot" in the active site by saturation mutagenesis as well as X-ray crystallographic analyses. We found that position 99 in the active site was involved in substrate discrimination. One mutant, Y99L, exhibited 11-fold improvement over wild-type in reactivity (kcat/Km toward the phosphotriesterase substrate ethyl-paraoxon, but showed 15-fold decrease toward the lactonase substrate δ-decanolactone, resulting in a 157-fold inversion of the substrate specificity. Structural analysis of Y99L revealed that the mutation causes a ∼6.6 Å outward shift of adjacent loop 7, which may cause increased flexibility of the active site and facilitate accommodation and/or catalysis of organophosphate substrate. This study provides for the PLL family an example of how the evolutionary route from promiscuity to specificity can derive from very few mutations, which promotes alteration in the conformational adjustment of the active site loops, in turn draws the capacity of substrate binding and activity.

  20. Stability and activity profile of alkaline protease produced from bacillus subtilis

    International Nuclear Information System (INIS)

    Anjum, S.; Mukhtar, H.; Nawaz, A.; Haq, I.U.

    2015-01-01

    The present study gives an insight into the effect of different activators and inhibitors on the activity and stability of alkaline proteases produced by Bacillus subtilis IH-72. The alkaline protease was strongly activated both by bivalent and monovalent cations such as Mg/sup 2+/, Mn/sup 2+/, Na/sup +/ and K/sup +/. The enzyme activity was considerably enhanced in the presence of fructose, galactose, glucose and mannitol. The enzyme was stabilized up to 10 days by immobilization on activated charcoal and was efficiently stabilized up to 2 months by lyophilization. The enzyme remained stable up to 19 days both at 4 degree C and 30 degree C in the presence of Mn/sup 2+/. However, it exhibited significant stability up to 22 days at 4 degree C and 30 degree C in the presence of fructose, galactose and polyethylene glycol. (author)

  1. Stability evaluation and correction of a pulsed neutron generator prompt gamma activation analysis system

    Science.gov (United States)

    Source output stability is important for accurate measurement in prompt gamma neutron activation. This is especially true when measuring low-concentration elements such as in vivo nitrogen (~2.5% of body weight). We evaluated the stability of the compact DT neutron generator within an in vivo nitrog...

  2. Beta activity in the premotor cortex is increased during stabilized as compared to normal walking.

    NARCIS (Netherlands)

    Bruijn, S.M.; van Dieen, J.H.; Daffertshofer, A.

    2015-01-01

    Walking on two legs is inherently unstable. Still, we humans perform remarkable well at it, mostly without falling. To gain more understanding of the role of the brain in controlling gait stability we measured brain activity using electro-encephalography (EEG) during stabilized and normal walking.

  3. Metals content of Glossoscolex paulistus extracellular hemoglobin: Its peroxidase activity and the importance of these ions in the protein stability.

    Science.gov (United States)

    Caruso, Celia S; Biazin, Ezer; Carvalho, Francisco A O; Tabak, Marcel; Bachega, José F R

    2016-08-01

    In this work we investigate the presence of divalent cations bound to the Glossoscolex paulistus (HbGp) hemoglobin and their effect over the protein stability and the peroxidase (POD) activity. Atomic absorption studies show that the HbGp iron content is consistent with the presence of 144 ions per protein. Moreover, using iron as a reference, the content of calcium was estimated as 30±4 ions per protein, independently of the EDTA pre-treatment or not prior to the acidic treatment performed in the protein digestion. The zinc content was 14±2 ions in the absence of EDTA pre-treatment, and 3±1 ions per protein in the presence of EDTA pre-treatment, implying the presence of one zinc ion per protomer (1/12 of the whole molecule). Finally, the copper concentration is negligible. Different from the vertebrate hemoglobins, where the effectors are usually organic anions, the hexagonal bilayer hemoglobins have as effectors inorganic cations that increase the oxygen affinity and stabilize the structure. Previous studies have suggested that the presence of divalent cations, such as copper and zinc, is related to the different types of antioxidant enzymatic activities as the superoxide dismutase (SOD) activity shown by giant hemoglobin from Lumbricus terrestris (HbLt). Recently, studies on HbGp crystal structure have confirmed the presence of Zn(2+) and Ca(2+) binding sites. The Ca(2+) sites are similar as observed in the HbLt crystal structure. Otherwise, the Zn(2+) sites have no relation with those observed in Cu/Zn SODs. Our peroxidase assays with guaiacol confirm the POD activity and the effect of the zinc ions for HbGp. Our present results on HbGp metal content and their stability effects is the first step to understand the role of these cations in HbGp function in the future. Copyright © 2016 Elsevier Inc. All rights reserved.

  4. Preparation of [In-111]-labeled-DTPA-bombesin conjugates at high specific activity and stability: Evaluation of labeling parameters and potential stabilizers

    Energy Technology Data Exchange (ETDEWEB)

    Pujatti, P.B., E-mail: pujatti.pb@gmail.com [Directory of Radiopharmacy, Nuclear and Energy Research Institute (IPEN/CNEN), Av. Prof. Lineu Prestes, 2242 - Cidade Universitaria da USP - Butanta, Sao Paulo - SP - Brazil - CEP: 05508-000 (Brazil); Massicano, A.V.F.; Mengatti, J.; Araujo, E.B. de [Directory of Radiopharmacy, Nuclear and Energy Research Institute (IPEN/CNEN), Av. Prof. Lineu Prestes, 2242 - Cidade Universitaria da USP - Butanta, Sao Paulo - SP - Brazil - CEP: 05508-000 (Brazil)

    2012-05-15

    The aim of the present work was to obtain stabilized high specific activity (HSA) {sup 111}In-labeled bombesin conjugates for preclinical evaluations. Parameters influencing the kinetics of labeling were investigated and the effect of stabilizers on HSA radiopeptides stability at room temperature were systematically categorized applying chromatography techniques. A SA of 174 GBq/{mu}mol was achieved with high radiochemical purity, but the labeled compounds exhibited low stability. The addition of stabilizers avoided their radiolysis and significantly increased their stability. - Highlights: Black-Right-Pointing-Pointer We aimed to obtain stabilized high specific activity (SA) {sup 111}In-labeled bombesin conjugates. Black-Right-Pointing-Pointer The effect of stabilizers on high SA radiopeptides stability were investigated. Black-Right-Pointing-Pointer A maximum specific activity of 174 GBq/{mu}mol was achieved. Black-Right-Pointing-Pointer The studied stabilizers significantly increased the stability of high SA radiopeptides. Black-Right-Pointing-Pointer These stabilized bombesin conjugates will be applied in preclinical studies.

  5. Assessment of the Spectral Stability of Libya 4, Libya 1, and Mauritania 2 Sites Using Earth Observing One Hyperion

    Science.gov (United States)

    Choi, Taeyoung; Xiong, Xiaoxiong; Angal, Amit; Chander, Gyanesh; Qu, John J.

    2014-01-01

    The objective of this paper is to formulate a methodology to assess the spectral stability of the Libya 4, Libya 1, and Mauritania 2 pseudo-invariant calibration sites (PICS) using Earth Observing One (EO-1) Hyperion sensor. All the available Hyperion collections, downloaded from the Earth Explorer website, were utilized for the three PICS. In each site, a reference spectrum is selected at a specific day in the vicinity of the region of interest (ROI) defined by Committee on Earth Observation Satellites (CEOS). A series of ROIs are predefined in the along-track direction with 196 spectral top-of-atmosphere reflectance values in each ROI. Based on the reference ROI spectrum, the spectral stability of these ROIs is evaluated by average deviations (ADs) and spectral angle mapper (SAM) methods in the specific ranges of time and geo-spatial locations. Time and ROI location-dependent SAM and AD results are very stable within +/- 2 deg and +/-1.7% of 1sigma standard deviations. Consequently, the Libya 4, Mauritania 2, and Libya 1 CEOS selected PICS are spectrally stable targets within the time and spatial swath ranges of the Hyperion collections.

  6. The Crystal Structure of a Quercetin 2,3-Dioxygenase from Bacillus subtilis Suggests Modulation of Enzyme Activity by a Change in the Metal Ion at the Active Site(s)

    Energy Technology Data Exchange (ETDEWEB)

    Gopal, B.; Madan, Lalima L.; Betz, Stephen F.; Kossiakoff, Anthony A. (Indian); (UC); (GeneFormatics)

    2010-11-10

    Common structural motifs, such as the cupin domains, are found in enzymes performing different biochemical functions while retaining a similar active site configuration and structural scaffold. The soil bacterium Bacillus subtilis has 20 cupin genes (0.5% of the total genome) with up to 14% of its genes in the form of doublets, thus making it an attractive system for studying the effects of gene duplication. There are four bicupins in B. subtilis encoded by the genes yvrK, yoaN, yxaG, and ywfC. The gene products of yvrK and yoaN function as oxalate decarboxylases with a manganese ion at the active site(s), whereas YwfC is a bacitracin synthetase. Here we present the crystal structure of YxaG, a novel iron-containing quercetin 2,3-dioxygenase with one active site in each cupin domain. Yxag is a dimer, both in solution and in the crystal. The crystal structure shows that the coordination geometry of the Fe ion is different in the two active sites of YxaG. Replacement of the iron at the active site with other metal ions suggests modulation of enzymatic activity in accordance with the Irving-Williams observation on the stability of metal ion complexes. This observation, along with a comparison with the crystal structure of YvrK determined recently, has allowed for a detailed structure-function analysis of the active site, providing clues to the diversification of function in the bicupin family of proteins.

  7. Active sites monitoring at Oak Ridge National Laboratory

    International Nuclear Information System (INIS)

    Ashwood, T.L.; Wickliff, D.S.; Morrissey, C.M.; Adair, H.L.

    1990-01-01

    Oak Ridge National Laboratory (ORNL) currently disposes of solid low-level radioactive wastes (LLW) in Solid Waste Storage Area (SWSA) 6 and stores transuranic (TRU) wastes in SWSA 5 North. Environmental monitoring of all TRU storage areas and those LLW disposal facilities active on or after September 1988 is required by U.S. Department of Energy (DOE) Order 5820.2A to provide for early detection of contaminant migration and to enable assessment of the performance of these facilities with regard to the exposure limits established in the order. In this paper, the authors develop a cost-effective monitoring program that is consistent with the authors' best understanding of the hydrogeology in the affected areas while complying with the DOE order. Active LLW disposal sites at ORNL consist of: lined auger holes with concrete bottoms, vertical concrete silos in trenches, and tumulus technology facilities (above-grade storage in concrete vaults on concrete pads to be covered by impermeable caps)

  8. Lack of dynamics in the MabA active site kills the enzyme activity: practical consequences for drug-design studies.

    Science.gov (United States)

    Poncet-Montange, Guillaume; Ducasse-Cabanot, Stephanie; Quemard, Annaick; Labesse, Gilles; Cohen-Gonsaud, Martin

    2007-08-01

    The MabA protein from Mycobacterium tuberculosis is a validated drug target. Previous structural studies of this protein showed dynamic behaviour in the catalytic site and described motion between an open 'active' holo form (with NADP) and a closed 'inactive' apo form (without NADP). Here, a mutation (G139A) is reported that leads to complete protein inactivation and freezes the catalytic site into its closed form, even in the presence of the cofactor. This observation suggests a new way to develop anti-MabA drugs via protein stabilization of the 'inactive' form.

  9. History and stabilization of the Plutonium Finishing Plant (PFP) complex, Hanford Site

    Energy Technology Data Exchange (ETDEWEB)

    Gerber, M.S., Fluor Daniel Hanford

    1997-02-18

    The 231-Z Isolation Building or Plutonium Metallurgy Building is located in the Hanford Site`s 200 West Area, approximately 300 yards north of the Plutonium Finishing Plant (PFP) (234-5 Building). When the Hanford Engineer Works (HEW) built it in 1944 to contain the final step for processing plutonium, it was called the Isolation Building. At that time, HEW used a bismuth phosphate radiochemical separations process to make `AT solution,` which was then dried and shipped to Los Alamos, New Mexico. (AT solution is a code name used during World War II for the final HEW product.) The process was carried out first in T Plant and the 224-T Bulk Reduction Building and B Plant and the 224-B Bulk Reduction Building. The 224-T and -B processes produced a concentrated plutonium nitrate stream, which then was sent in 8-gallon batches to the 231-Z Building for final purification. In the 231-Z Building, the plutonium nitrate solution underwent peroxide `strikes` (additions of hydrogen peroxide to further separate the plutonium from its carrier solutions), to form the AT solution. The AT solution was dried and shipped to the Los Alamos Site, where it was made into metallic plutonium and then into weapons hemispheres.` The 231-Z Building began `hot` operations (operations using radioactive materials) with regular runs of plutonium nitrate on January 16, 1945.

  10. Stability of perchlorate hydrates and their liquid solutions at the Phoenix landing site, Mars

    Science.gov (United States)

    Chevrier, Vincent F.; Hanley, Jennifer; Altheide, Travis S.

    2009-05-01

    We studied the low-temperature properties of sodium and magnesium perchlorate solutions as potential liquid brines at the Phoenix landing site. We determined their theoretical eutectic values to be 236 ± 1 K for 52 wt% sodium perchlorate and 206 ± 1 K for 44.0 wt% magnesium perchlorate. Evaporation rates of solutions at various concentrations were measured under martian conditions, and range from 0.07 to 0.49 mm h-1 for NaClO4 and from 0.06 to 0.29 mm h-1 for Mg(ClO4)2. The extrapolation to Phoenix landing site conditions using our theoretical treatment shows that perchlorates are liquid during the summer for at least part of the day, and exhibit very low evaporation rates. Moreover, magnesium perchlorate eutectic solutions are thermodynamically stable over vapour and ice during a few hours a day. We conclude that liquid brines may be present and even stable for short periods of time at the Phoenix landing site.

  11. Delay-dependent robust stabilization and H∞ control for neural networks with various activation functions

    Science.gov (United States)

    Sakthivel, R.; Mathiyalagan, K.; Anthoni, S. Marshal

    2012-04-01

    This paper considers the problem of robust stabilization for a class of uncertain neural networks with various activation functions and mixed time delays. The aim is to derive a H∞ control law to ensure the robust stability of the closed-loop system about its equilibrium with parameter uncertainties. By employing the Lyapunov stability theory and the matrix inequality technique, a new set of sufficient conditions is presented for the existence of the H∞ control problem. The stability criteria are derived in terms of linear matrix inequalities (LMIs) which can be solved easily by the Matlab LMI toolbox. In addition to the requirement of global robust stabilization, for a prescribed H∞ performance level the stabilizing controller gain matrices for all delays to satisfy the upper bound of the time-varying delay are required to be obtained. Numerical examples are presented to illustrate the effectiveness of the proposed method.

  12. Wellbore stability analysis in chemically active shale formations

    Directory of Open Access Journals (Sweden)

    Shi Xiang-Chao

    2016-01-01

    Full Text Available Maintaining wellbore stability involves significant challenges when drilling in low-permeability reactive shale formations. In the present study, a non-linear thermo-chemo-poroelastic model is provided to investigate the effect of chemical, thermal, and hydraulic gradients on pore pressure and stress distributions near the wellbores. The analysis indicates that when the solute concentration of the drilling mud is higher than that of the formation fluid, the pore pressure and the effective radial and tangential stresses decrease, and v. v. Cooling of the lower salinity formation decreases the pore pressure, radial and tangential stresses. Hole enlargement is the combined effect of shear and tensile failure when drilling in high-temperature shale formations. The shear and tensile damage indexes reveal that hole enlargement occurs in the vicinity of the wellbore at an early stage of drilling. This study also demonstrates that shale wellbore stability exhibits a time-delay effect due to changes in the pore pressure and stress. The delay time computed with consideration of the strength degradation is far less than that without strength degradation.

  13. Engineering a highly active thermophilic β-glucosidase to enhance its pH stability and saccharification performance.

    Science.gov (United States)

    Xia, Wei; Xu, Xinxin; Qian, Lichun; Shi, Pengjun; Bai, Yingguo; Luo, Huiying; Ma, Rui; Yao, Bin

    2016-01-01

    β-Glucosidase is an important member of the biomass-degrading enzyme system, and plays vital roles in enzymatic saccharification for biofuels production. Candidates with high activity and great stability over high temperature and varied pHs are always preferred in industrial practice. To achieve cost-effective biomass conversion, exploring natural enzymes, developing high level expression systems and engineering superior mutants are effective approaches commonly used. A newly identified β-glucosidase of GH3, Bgl3A, from Talaromyces leycettanus JCM12802, was overexpressed in yeast strain Pichia pastoris GS115, yielding a crude enzyme activity of 6000 U/ml in a 3 L fermentation tank. The purified enzyme exhibited outstanding enzymatic properties, including favorable temperature and pH optima (75 °C and pH 4.5), good thermostability (maintaining stable at 60 °C), and high catalytic performance (with a specific activity and catalytic efficiency of 905 U/mg and 9096/s/mM on pNPG, respectively). However, the narrow stability of Bgl3A at pH 4.0-5.0 would limit its industrial applications. Further site-directed mutagenesis indicated the role of excessive O-glycosylation in pH liability. By removing the potential O-glycosylation sites, two mutants showed improved pH stability over a broader pH range (3.0-10.0). Besides, with better stability under pH 5.0 and 50 °C compared with wild type Bgl3A, saccharification efficiency of mutant M1 was improved substantially cooperating with cellulase Celluclast 1.5L. And mutant M1 reached approximately equivalent saccharification performance to commercial β-glucosidase Novozyme 188 with identical β-glucosidase activity, suggesting its great prospect in biofuels production. In this study, we overexpressed a novel β-glucosidase Bgl3A with high specific activity and high catalytic efficiency in P. pastoris. We further proved the negative effect of excessive O-glycosylation on the pH stability of Bgl3A, and enhanced the p

  14. Revegetation/rock cover for stabilization of inactive uranium mill tailings disposal sites

    International Nuclear Information System (INIS)

    Beedlow, P.A.; McShane, M.C.; Cadwell, L.L.

    1982-07-01

    Pacific Northwest Laboratory is developing design and performance guidelines for surface stabilization of inactive uranium mill tailings. In this work, vegetation and rock covers are being evaluated for maintaining long-term integrity of impoundment systems. Methods are being developed to estimate erosion rates associated with rock and/or vegetation covers, and to determine the effects of surface treatments on soil moisture. Interactions between surface treatments and barriers (radon and biological) are being studied as well. The product will be a set of guidelines to aid in designing surface covers. This report presents the status of this program and a discussion of considerations pertinent to the application of surface covers to tailings. Test plots located in Grand Junction, Colorado and Waterflow, New Mexico are being used to study: (1) the interactions between vegetation and radon and biological barriers, (2) the effects of surface covers on soil moisture, and (3) the effects of rock covers on vegetation

  15. Identification of Active Edge Sites for Electrochemical H2 Evolution from MoS2 Nanocatalysts

    DEFF Research Database (Denmark)

    Jaramillo, Thomas; Jørgensen, Kristina Pilt; Bonde, Jacob

    2007-01-01

    The identification of the active sites in heterogeneous catalysis requires a combination of surface sensitive methods and reactivity studies. We determined the active site for hydrogen evolution, a reaction catalyzed by precious metals, on nanoparticulate molybdenum disulfide (MoS2) by atomically....... Electrocatalytic activity measurements for hydrogen evolution correlate linearly with the number of edge sites on the MoS2 catalyst....

  16. Global Asymptotic Stability of Impulsive CNNs with Proportional Delays and Partially Lipschitz Activation Functions

    Directory of Open Access Journals (Sweden)

    Xueli Song

    2014-01-01

    Full Text Available This paper researches global asymptotic stability of impulsive cellular neural networks with proportional delays and partially Lipschitz activation functions. Firstly, by means of the transformation vi(t=ui(et, the impulsive cellular neural networks with proportional delays are transformed into impulsive cellular neural networks with the variable coefficients and constant delays. Secondly, we provide novel criteria for the uniqueness and exponential stability of the equilibrium point of the latter by relative nonlinear measure and prove that the exponential stability of equilibrium point of the latter implies the asymptotic stability of one of the former. We furthermore obtain a sufficient condition to the uniqueness and global asymptotic stability of the equilibrium point of the former. Our method does not require conventional assumptions on global Lipschitz continuity, boundedness, and monotonicity of activation functions. Our results are generalizations and improvements of some existing ones. Finally, an example and its simulations are provided to illustrate the correctness of our analysis.

  17. Remedial Action Plan and site design for stabilization of the inactive uranium mill tailings site at Durango, Colorado: Attachment 6, Supplemental standard for Durango processing site

    International Nuclear Information System (INIS)

    1991-12-01

    Excavation control to the 15 pCi/g radium-226 (Ra-226) standard at certain areas along the Animas River on the Durango Site would require extensive engineering and construction support. Elevated Ra-226 concentrations have been encountered immediately adjacent to the river at depths in excess of 7 feet below the present river stage. Decontamination to such depths to ensure compliance with the EPA standards will, in our opinion, become unreasonable. This work does not appear to be in keeping with the intent of the standards. Because the principal reason for radium removal is reduction of radon daughter concentrations (RDC) in homes to be built onsite, and because radon produced at depth will be attenuated in clean fill cover before entering such homes, it is appropriate to calculate the depth of excavation needed under a home to reduce RDC to acceptable levels. Potential impact was assessed through radon emanation estimation, using the RAECOM computer model. Elevated Ra-226 concentrations were encountered during final radium excavation of the flood plain below the large tailings pile, adjacent to the slag area. Data from 7 test pits excavated across the area were analyzed to provide an estimate of the Ra-226 concentration profile. Results are given in this report

  18. Characterization of the activity and stability of supported cobalt catalysts for the steam reforming of ethanol

    Science.gov (United States)

    Batista, Marcelo S.; Santos, Rudye K. S.; Assaf, Elisabete M.; Assaf, José M.; Ticianelli, Edson A.

    This paper reports results of studies of the catalytic activity and stability of supported cobalt catalysts for steam reforming of ethanol. Co/Al 2O 3, Co/SiO 2, and Co/MgO catalysts were prepared by an impregnation method and characterized by X-ray diffraction, atomic absorption spectroscopy, Raman spectroscopy, and temperature programmed reduction with hydrogen. The results showed the presence of Co 3O 4 and CoO x species interacting with Al 2O 3 or MgO and formed after a calcination step. It was evident that only Co 0 sites are active for the steam reforming of ethanol. All materials showed high levels of ethanol conversion, with molar yields of about 70% of hydrogen and 30% of CO+CO 2+CH 4 in the gaseous mixture. The Co/Al 2O 3 catalyst also produced ethylene through a dehydration reaction of ethanol. It is proposed that the methane formation on Co/SiO 2 catalysts occurs by methanation of CO and by ethanol decomposition. After 9 h of reaction, 14-24% (w/w) of carbon was deposited on all catalysts, indicating that a well characterized deactivation of the materials is due to coke deposition.

  19. DNFSB Recommendation 94-1 Hanford Site Integrated Stabilization Management Plan. Volume 1

    Energy Technology Data Exchange (ETDEWEB)

    McCormack, R.L.

    1995-08-01

    This document describes the plans of the Hanford Site for the safe interim storage of fissile materials. Currently, spent nuclear fuels reside in storage basins that have leaked in the past and are projected to leak in the future. Other problems in the basins include; sludge from decomposition, degraded cladding of fuel elements, and construction defects which make the basins seismically unsafe. This management plan describes the time and cost that it will take to implement a safe interim storage plan for the fissile materials.

  20. Evaluation of the geologic relations and seismotectonic stability of the Yucca Mountain area, Nevada Nuclear Waste Site Investigation (NNWSI)

    International Nuclear Information System (INIS)

    1988-10-01

    This document describes activities for the year ending 30 June 1988 by staff members of the Seismological Laboratory in support of the Yucca Mountain site assessment program. Participants include James N. Brune, Director, John Anderson, William Peppin, Keith Priestley, Martha Savage, and Ute Vetter. Activities during the year centered largely around acquisition of equipment to be used for site characterization plan for Yucca Mountain. Due to modifications in the scheduling and level of funding, this work has not progressed as originally anticipated. The report describes progress in seven areas, listed in approximate order of significance to the Yucca Mountain project. These are: (1) equipment acquisition, (2) review of the draft site characterization plan, (3) studies of earthquake sequence related to the tectonic problems at Yucca Mountain, (4) a review of the work of Szymanski in relation to Task 4 concerns, (5) coordination meetings with USGS, DOE and NRC personnel, (6) studies related to Yucca Mountain and (7) other studies

  1. An appraisal of the enzyme stability-activity trade-off.

    Science.gov (United States)

    Miller, Scott R

    2017-07-01

    A longstanding idea in evolutionary physiology is that an enzyme cannot jointly optimize performance at both high and low temperatures due to a trade-off between stability and activity. Although a stability-activity trade-off has been observed for well-characterized examples, such a trade-off is not imposed by any physical chemical constraint. To better understand the pervasiveness of this trade-off, I investigated the stability-activity relationship for comparative biochemical studies of purified orthologous enzymes identified by a literature search. The nature of this relationship varied greatly among studies. Notably, studies of enzymes with low mean synonymous nucleotide sequence divergence were less likely to exhibit the predicted negative correlation between stability and activity. Similarly, a survey of directed evolution investigations of the stability-activity relationship indicated that these traits are often uncoupled among nearly identical yet phenotypically divergent enzymes. This suggests that the presumptive trade-off often reported for investigations of enzymes with high mean sequence divergence may in some cases instead be a consequence of the degeneration over time of enzyme function in unselected environments, rather than a direct effect of thermal adaptation. The results caution against the general assertion of a stability-activity trade-off during enzyme adaptation. © 2017 The Author(s). Evolution © 2017 The Society for the Study of Evolution.

  2. Ligand Exchange-Mediated Activation and Stabilization of a Re-Based Olefin Metathesis Catalyst by Chlorinated Alumina.

    Science.gov (United States)

    Gallo, Alessandro; Fong, Anthony; Szeto, Kai C; Rieb, Julia; Delevoye, Laurent; Gauvin, Régis M; Taoufik, Mostafa; Peters, Baron; Scott, Susannah L

    2016-10-05

    Extensive chlorination of γ-Al 2 O 3 results in the formation of highly Lewis acidic surface domains depleted in surface hydroxyl groups. Adsorption of methyltrioxorhenium (MTO) onto these chlorinated domains serves to activate it as a low temperature, heterogeneous olefin metathesis catalyst and confers both high activity and high stability. Characterization of the catalyst reveals that the immobilized MTO undergoes partial ligand exchange with the surface, whereby some Re sites acquire a chloride ligand from the modified alumina while donating an oxo ligand to the support. More specifically, Re L III -edge EXAFS and DFT calculations support facile ligand exchange between MTO and Cl-Al 2 O 3 to generate [CH 3 ReO 2 Cl + ] fragments that interact with a bridging oxygen of the support via a Lewis acid-base interaction. According to IR and solid-state NMR, the methyl group remains intact, and does not evolve spontaneously to a stable methylene tautomer. Nevertheless, the chloride-promoted metathesis catalyst is far more active and productive than MTO/γ-Al 2 O 3 , easily achieving a TON of 100 000 for propene metathesis in a flow reactor at 10 °C (compared to TON < 5000 for the nonchlorinated catalyst). Increased activity is a consequence of both a larger fraction of active sites and a higher intrinsic activity for the new sites. Increased stability is tentatively attributed to a stronger interaction between MTO and chlorinated surface regions, as well as extensive depletion of the Brønsted acidic surface hydroxyl population. The reformulated catalyst represents a major advance for Re-based metathesis catalysts, whose widespread use has thus far been severely hampered by their instability.

  3. Collagen fibril surface displays a constellation of sites capable of promoting fibril assembly, stability, and hemostasis

    Energy Technology Data Exchange (ETDEWEB)

    Orgel, J.P.; Antipova, O.; Sagi, I.; Bitler, A.; Qiu, D.; Wang, R.; Xu, Y.; San Antonio, J.D. (IIT)

    2011-12-14

    Fibrillar collagens form the structural basis of organs and tissues including the vasculature, bone, and tendon. They are also dynamic, organizational scaffolds that present binding and recognition sites for ligands, cells, and platelets. We interpret recently published X-ray diffraction findings and use atomic force microscopy data to illustrate the significance of new insights into the functional organization of the collagen fibril. These data indicate that collagen's most crucial functional domains localize primarily to the overlap region, comprising a constellation of sites we call the 'master control region.' Moreover, the collagen's most exposed aspect contains its most stable part - the C-terminal region that controls collagen assembly, cross-linking, and blood clotting. Hidden beneath the fibril surface exists a constellation of 'cryptic' sequences poised to promote hemostasis and cell - collagen interactions in tissue injury and regeneration. These findings begin to address several important, and previously unresolved, questions: How functional domains are organized in the fibril, which domains are accessible, and which require proteolysis or structural trauma to become exposed? Here we speculate as to how collagen fibrillar organization impacts molecular processes relating to tissue growth, development, and repair.

  4. Environmentally Persistent Free Radicals in Soils of Past Coking Sites: Distribution and Stabilization.

    Science.gov (United States)

    Jia, Hanzhong; Zhao, Song; Nulaji, Gulimire; Tao, Kelin; Wang, Fu; Sharma, Virender K; Wang, Chuanyi

    2017-06-06

    This study presents the existence of environmentally persistent free radicals (EPFRs) in soils of past coking sites, mainly contaminated by polycyclic aromatic hydrocarbons (PAHs). Measurements of EPFRs were conducted by electron paramagnetic resonance (EPR) technique with numerous soil samples, which were collected from different distances (0-1000 m) and different depths (0-30 cm) of three contaminant sources. EPR signals with ∼3 × 10 17 radicals/g of the soil samples were obtained, which are very similar to that generated in PAHs contaminated clays, that is, g = 2.0028-2.0036. Concentrations of PAHs and soil components were determined to understand their role in producing EPFRs. PAHs, clay, and iron predominately contributed to generating EPRFs. Meanwhile, organic matter negatively influenced the production of EPRFs. The effects of environmental factors (moisture and oxic/anoxic) were also studied to probe the persistency of EPFRs under various simulated conditions. The EPFRs are stable under relatively dry and oxic conditions. Under anoxic conditions without O 2 and H 2 O, the spin densities decrease initially, followed by gradual increase before attaining constant values in two months period time. The present work implies that continuous formation of EPFRs induced by PAHs is largely responsible for the presence of relatively stable radicals in soils of coking sites.

  5. Statistical optimization of activity and stability of β-xylanase ...

    African Journals Online (AJOL)

    A factorial design was performed to find the best conditions of pH and temperature for #946-xylanase activity and to maintain its activity for prolonged periods of time of pure xylanase produced by newly isolated Thermomyces lanuginosus THKU-49. The central composite design (CCD) used for the analysis of treatment ...

  6. Conceptual design for the demonstration and evaluation of stabilization and closure techniques of a low-level radioactive waste disposal site

    International Nuclear Information System (INIS)

    Cox, L.C.

    1987-01-01

    Long term stabilization and closure of radioactive or hazardous waste disposal sites is a critical element in waste management which is presently undemonstrated. This report represents an integration of stabilization and closure methodology researched at ORNL and other locations into a design, and ultimately a demonstration of long term passive stabilization and closure techniques. The chosen demonstration site is a 19 trench low level waste disposal site within Solid Waste Storage Area (SWSA) No. 6 at ORNL. Design criteria included prevention of biological intrusion (animals and plant roots), waste stabilization, hydrological isolation, failure detection, run-off and infiltration monitoring, and passive performance evaluation capability. These criteria are satisfied through incorporation of these basic components: dynamic compaction; in situ chemical grouting; high density polyethylene (HDPE); high swelling bentonite; rock/gravel animal and root barrier; native soil cap; and under-cap and surface drainage

  7. Cliff stability assessment using electrical resistivity tomography at the historic WWII D-Day invasion site, Pointe du Hoc, France

    Science.gov (United States)

    Everett, M. E.; Udphuay, S.; Warden, R.

    2007-05-01

    The 1944 D-Day invasion site at Pointe du Hoc, Normandy, France is an important WWII battlefield and cultural resource but is at risk from chalk cliff collapse. The American Battle Monuments Commission tasked us to evaluate the geohazard to the observation post and other cliff-side buildings of historical significance. Geophysical multi-electrode resistivity profiling is used to study cliff stability and the condition of the observation- post foundations. Preliminary 2-D geological interpretations are provided of individual profiles. The copious steel, concrete and void spaces at the site renders hydrogeological interpretation challenging but tractable. The cliff face appears to be relatively intact and well-drained. Several routes taken by groundwater into fractures within the chalk were identified mainly on the western side of the site. The eastern side is drier and somewhat sheltered from the Atlantic storms but may contain large void spaces that could efficiently transmit groundwater flow during heavy precipitation events, thereby imperiling the major antiaircraft gun emplacement occupied by Col. Rudder in the early days of the Allied invasion. The forward German observation post perched close to the sea stack, which now hosts the U.S. Ranger memorial, may be moving with the soil and not securely anchored to bedrock. A complex failure mechanism is identified as a combination of groundwater dissolution of the fractured chalk and sea wave attack at the cliff base.

  8. Leisure Activities and Change in Cognitive Stability: A Multivariate Approach

    Directory of Open Access Journals (Sweden)

    Nathalie Mella

    2017-03-01

    Full Text Available Aging is traditionally associated with cognitive decline, attested by slower reaction times and poorer performance in various cognitive tasks, but also by an increase in intraindividual variability (IIV in cognitive performance. Results concerning how lifestyle activities protect from cognitive decline are mixed in the literature and all focused on how it affects mean performance. However, IIV has been proven to be an index more sensitive to age differences, and very little is known about the relationships between lifestyle activities and change in IIV in aging. This longitudinal study explores the association between frequency of physical, social, intellectual, artistic, or cultural activities and age-related change in various cognitive abilities, considering both mean performance and IIV. Ninety-six participants, aged 64–93 years, underwent a battery of cognitive tasks at four measurements over a seven-year period, and filled out a lifestyle activity questionnaire. Linear multilevel models were used to analyze the associations between change in cognitive performance and five types of activities. Results showed that the practice of leisure activities was more strongly associated with IIV than with mean performance, both when considering overall level and change in performance. Relationships with IIV were dependent of the cognitive tasks considered and overall results showed protective effects of cultural, physical and intellectual activities on IIV. These results underline the need for considering IIV in the study of age-related cognitive change.

  9. Beta activity in the premotor cortex is increased during stabilized as compared to normal walking

    Directory of Open Access Journals (Sweden)

    Sjoerd M. Bruijn

    2015-10-01

    Full Text Available Walking on two legs is inherently unstable. Still, we humans perform remarkable well at it, mostly without falling. To gain more understanding of the role of the brain in controlling gait stability we measured brain activity using electro-encephalography (EEG during stabilized and normal walking.Subjects walked on a treadmill in two conditions, each lasting 10 minutes; normal, and while being laterally stabilized by elastic cords. Kinematics of trunk and feet, electro-myography (EMG of neck muscles, as well as 64-channel EEG were recorded. To assess gait stability the local divergence exponent, step width, and trunk range of motion were calculated from the kinematic data. We used independent component analysis to remove movement, EMG, and eyeblink artifacts from the EEG, after which dynamic imaging of coherent sources beamformers were determined to identify cortical sources that showed a significant difference between conditions. Stabilized walking led to a significant increase in gait stability, i.e. lower local divergence exponents. Beamforming analysis of the beta band activity revealed significant sources in bilateral pre-motor cortices. Projection of sensor data on these sources showed a significant difference only in the left premotor area, with higher beta power during stabilized walking, specifically around push-off, although only significant around contralateral push-off. It appears that even during steady gait the cortex is involved in the control of stability.

  10. Forkhead box protein A2 (FOXA2 protein stability and activity are regulated by sumoylation.

    Directory of Open Access Journals (Sweden)

    Narasimhaswamy S Belaguli

    Full Text Available The forkhead box protein A2 (FOXA2 is an important regulator of glucose and lipid metabolism and organismal energy balance. Little is known about how FOXA2 protein expression and activity are regulated by post-translational modifications. We have identified that FOXA2 is post-translationally modified by covalent attachment of a small ubiquitin related modifier-1 (SUMO-1 and mapped the sumoylation site to the amino acid lysine 6 (K6. Preventing sumoylation by mutating the SUMO acceptor K6 to arginine resulted in downregulation of FOXA2 protein but not RNA expression in INS-1E insulinoma cells. K6R mutation also downregulated FOXA2 protein levels in HepG2 hepatocellular carcinoma cells, HCT116 colon cancer cells and LNCaP and DU145 prostate cancer cells. Further, interfering with FOXA2 sumoylation through siRNA mediated knockdown of UBC9, an essential SUMO E2 conjugase, resulted in downregulation of FOXA2 protein levels. Stability of sumoylation deficient FOXA2K6R mutant protein was restored when SUMO-1 was fused in-frame. FOXA2 sumoylation and FOXA2 protein levels were increased by PIAS1 SUMO ligase but not a SUMO ligase activity deficient PIAS1 mutant. Although expressed at lower levels, sumoylation deficient FOXA2K6R mutant protein was detectable in the nucleus indicating that FOXA2 nuclear localization is independent of sumoylation. Sumoylation increased the transcriptional activity of FOXA2 on Pdx-1 area I enhancer. Together, our results show that sumoylation regulates FOXA2 protein expression and activity.

  11. Forkhead box protein A2 (FOXA2) protein stability and activity are regulated by sumoylation.

    Science.gov (United States)

    Belaguli, Narasimhaswamy S; Zhang, Mao; Brunicardi, F Charles; Berger, David H

    2012-01-01

    The forkhead box protein A2 (FOXA2) is an important regulator of glucose and lipid metabolism and organismal energy balance. Little is known about how FOXA2 protein expression and activity are regulated by post-translational modifications. We have identified that FOXA2 is post-translationally modified by covalent attachment of a small ubiquitin related modifier-1 (SUMO-1) and mapped the sumoylation site to the amino acid lysine 6 (K6). Preventing sumoylation by mutating the SUMO acceptor K6 to arginine resulted in downregulation of FOXA2 protein but not RNA expression in INS-1E insulinoma cells. K6R mutation also downregulated FOXA2 protein levels in HepG2 hepatocellular carcinoma cells, HCT116 colon cancer cells and LNCaP and DU145 prostate cancer cells. Further, interfering with FOXA2 sumoylation through siRNA mediated knockdown of UBC9, an essential SUMO E2 conjugase, resulted in downregulation of FOXA2 protein levels. Stability of sumoylation deficient FOXA2K6R mutant protein was restored when SUMO-1 was fused in-frame. FOXA2 sumoylation and FOXA2 protein levels were increased by PIAS1 SUMO ligase but not a SUMO ligase activity deficient PIAS1 mutant. Although expressed at lower levels, sumoylation deficient FOXA2K6R mutant protein was detectable in the nucleus indicating that FOXA2 nuclear localization is independent of sumoylation. Sumoylation increased the transcriptional activity of FOXA2 on Pdx-1 area I enhancer. Together, our results show that sumoylation regulates FOXA2 protein expression and activity.

  12. Enzyme-polymer composites with high biocatalytic activity and stability

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Jungbae; Kosto, Timothy J.; Manimala, Joseph C.; Nauman, E B.; Dordick, Jonathan S.

    2004-08-22

    We have applied vacuum-spraying and electrospinning to incorporate an enzyme into a polymer matrix, creating a novel and highly active biocatalytic composite. As a unique technical approach, enzymes were co-dissolved in toluene with polymers, and the solvent was then rapidly removed by injecting the mixture into a vacuum chamber or by electrospinning. Subsequent crosslinking of the enzyme with glutaraldehyde resulted in stable entrapped enzyme within the polymeric matrices. For example, an amorphous composite of alpha-chymotrypsin and polyethylene showed no significant loss of enzymatic activity in aqueous buffer for one month. Nanofibers of alpha-chymotrypsin and polystyrene also showed no decrease in activity for more than two weeks. The normalized activity of amorphous composite in organic solvents was 3-13 times higher than that of native alpha-chymotrypsin. The activity of nanofibers was 5-7 times higher than that of amorphous composite in aqueous buffer solution. The composites of alpha-chymotrypsin and polymers demonstrate the feasibility of obtaining a wide variety of active and stable biocatalytic materials with many combinations of enzymes and polymers.

  13. Electrocatalytic Activity and Stability of M-Fe Catalysts Synthesized by Polymer Complex Method for PEFC Cathode

    KAUST Repository

    Ou, Yiwei

    2011-11-01

    The polymerized complex (PC) method was used to synthesize highly dispersed iron-based catalysts for the oxygen reduction reaction (ORR). The catalysts were prepared with an addition of 1,10-phenanthroline (Phen) and transition metals (M), such as Ta, Ti, and W, in an attempt to enhance the ORR activity and durability of the catalysts. The composition and properties of the catalysts were characterized by thermogravimetric analysis, X-ray diffraction, and X-ray photoelectron spectroscopy. The catalyst components, after extensive dissolution in a strong acid solution, were characterized by inductively coupled plasma mass spectroscopy and ultraviolet-visible spectroscopy. It was found that the Ti-Fe catalyst showed improved ORR performance, and the Ta-Fe catalyst showed enhanced stability towards ORR in acidic solution. The catalytic activity and stability for ORR was observed by adding Ti or Ta into the catalyst formulation, suggesting that the interaction between added hetero-ions (Ti and Ta) and ionic Fe active sites was beneficial for the ORR. A single-cell test with the synthesized catalyst in the cathode initially generated a high power density, but the low stability remains an issue to be solved.

  14. Using the Sonoran Desert test site to monitor the long-term radiometric stability of the Landsat TM/ETM+ and Terra MODIS sensors

    Science.gov (United States)

    Angal, A.; Xiong, X.; Choi, T.; Chander, G.; Wu, A.

    2009-01-01

    Pseudo-invariant ground targets have been extensively used to monitor the long-term radiometric calibration stability of remote sensing instruments. The NASA MODIS Characterization Support Team (MCST), in collaboration with members from the U.S. Geological Survey (USGS) Earth Resources Observation and Science (EROS) Center, has previously demonstrated the use of pseudo-invariant ground sites for the long-term stability monitoring of Terra MODIS and Landsat 7 ETM+ sensors. This paper focuses on the results derived from observations made over the Sonoran Desert. Additionally, Landsat 5 TM data over the Sonoran Desert site were used to evaluate the temporal stability of this site. Top-ofatmosphere (TOA) reflectances were computed for the closely matched TM, ETM+, and MODIS spectral bands over selected regions of interest. The impacts due to different viewing geometries, or the effect of test site Bi-directional Reflectance Distribution Function (BRDF), are also presented. ?? 2009 SPIE.

  15. Modification of the ATP inhibitory site of the Ascaris suum phosphofructokinase results in the stabilization of an inactive T state

    Energy Technology Data Exchange (ETDEWEB)

    Rao, G.S.J.; Cook, P.F.; Harris, B.G. (Univ. of North Texas, Fort Worth (United States))

    1991-10-15

    Treatment of the Ascaris suum phosphofructokinase (PFK) with 2{prime},3{prime}-dialdehyde ATP (oATP) results in an enzyme form that is inactive. The conformational integrity of the active site, however, is preserved, suggesting that oATP modification locks the PFK into an inactive T state that cannot be activated. A rapid, irreversible first-order inactivation of the PFK is observed in the presence of oATP. The rate of inactivation is saturable and gives a K{sub oATP} of 1.07 {plus minus} 0.27 mM. Complete protection against inactivation is afforded by high concentrations of ATP. This desensitized enzyme incorporates only 0.2-0.3 mol of ({sup 3}H)oATP/subunit, suggesting that in te native enzyme inactivation perhaps results from the modification of the ATP inhibitory site rather than the catalytic site. Modification of an active-site thiol by 4,4{prime}-dithiodipyridine is prevented yb ATP before and after oATP treatment. Finally, gel filtration HPLC studies show that the oATP-modified enzyme retains its tetrameric state and neither the tryptophan fluorescence nor the circular dichroic spectra of the modified enzyme are affected by fructose 2,6-bisphosphate, suggesting that the enzyme is locked into a tetrameric inactive T state.

  16. Role of cysteine residues in the structure, stability, and alkane producing activity of cyanobacterial aldehyde deformylating oxygenase.

    Directory of Open Access Journals (Sweden)

    Yuuki Hayashi

    Full Text Available Aldehyde deformylating oxygenase (AD is a key enzyme for alkane biosynthesis in cyanobacteria, and it can be used as a catalyst for alkane production in vitro and in vivo. However, three free Cys residues in AD may impair its catalytic activity by undesired disulfide bond formation and oxidation. To develop Cys-deficient mutants of AD, we examined the roles of the Cys residues in the structure, stability, and alkane producing activity of AD from Nostoc punctiforme PCC 73102 by systematic Cys-to-Ala/Ser mutagenesis. The C71A/S mutations reduced the hydrocarbon producing activity of AD and facilitated the formation of a dimer, indicating that the conserved Cys71, which is located in close proximity to the substrate-binding site, plays crucial roles in maintaining the activity, structure, and stability of AD. On the other hand, mutations at Cys107 and Cys117 did not affect the hydrocarbon producing activity of AD. Therefore, we propose that the C107A/C117A double mutant is preferable to wild type AD for alkane production and that the double mutant may be used as a pseudo-wild type protein for further improvement of the alkane producing activity of AD.

  17. Finding of no significant impact shipment of stabilized mixed waste from the K-25 Site to an off-site commercial disposal facility, Oak Ridge K-25 Site, Oak Ridge, Tennessee

    International Nuclear Information System (INIS)

    1994-01-01

    The Department of Energy (DOE) has prepared an Environmental Assessment (EA) for the shipment of stabilized mixed waste, removed from K-1407-B and -C ponds, to an off-site commercial disposal facility (Envirocare) for permanent land disposal. Based on the analysis in the EA, DOE has determined that the proposed action is not a major federal action significantly affecting the quality of the human environment, within the meaning of the National Environmental Policy Act (NEPA) of 1969. Therefore, the preparation of an environmental impact statement (EIS) is not required, and DOE is issuing this Finding of No Significant Impact (FONSI)

  18. Seismic stability of the survey areas of potential sites for the deep geological repository of the spent nuclear fuel

    Directory of Open Access Journals (Sweden)

    Kaláb Zdeněk

    2017-07-01

    Full Text Available This paper deals with the seismic stability of the survey areas of potential sites for the deep geological repository of the spent nuclear fuel in the Czech Republic. The basic source of data for historical earthquakes up to 1990 was the seismic website [10]. The most intense earthquake described occurred on September 15, 1590 in the Niederroesterreich region (Austria in the historical period; its reported intensity is Io = 8-9. The source of the contemporary seismic data for the period since 1991 to the end of 2014 was the website [11]. It may be stated based on the databases and literature review that in the period from 1900, no earthquake exceeding magnitude 5.1 originated in the territory of the Czech Republic.

  19. Robotics and Automation Activities at the Savannah River Site: A Site Report for SUBWOG 39F

    International Nuclear Information System (INIS)

    Teese, G.D.

    1995-01-01

    The Savannah River Site has successfully used robots, teleoperators, and remote video to reduce exposure to ionizing radiation, improve worker safety, and improve the quality of operations. Previous reports have described the use of mobile teleoperators in coping with a high level liquid waste spill, the removal of highly contaminated equipment, and the inspection of nuclear reactor vessels. This report will cover recent applications at the Savannah River, as well as systems which SRS has delivered to other DOE site customers

  20. PROGRESS WITH K BASINS SLUDGE RETRIEVAL STABILIZATION & PACKAGING AT THE HANFORD NUCLEAR SITE

    Energy Technology Data Exchange (ETDEWEB)

    KNOLLMEYER, P.M.; PHILLIPS, C; TOWNSON, P.S.

    2006-01-30

    This paper shows how Fluor Hanford and BNG America have combined nuclear plant skills from the U.S. and the U.K. to devise methods to retrieve and treat the sludge that has accumulated in K Basins at the Hanford Site over many years. Retrieving the sludge is the final stage in removing fuel and sludge from the basins to allow them to be decontaminated and decommissioned, so as to remove the threat of contamination of the Columbia River. A description is given of sludge retrieval using vacuum lances and specially developed nozzles and pumps into Consolidation Containers within the basins. The special attention that had to be paid to the heat generation and potential criticality issues with the irradiated uranium-containing sludge is described. The processes developed to re-mobilize the sludge from the Consolidation Containers and pump it through flexible and transportable hose-in-hose piping to the treatment facility are explained with particular note made of dealing with the abrasive nature of the sludge. The treatment facility, housed in an existing Hanford building, is described, and the uranium-corrosion and grout packaging processes explained. The uranium corrosion process is a robust, tempered process very suitable for dealing with a range of differing sludge compositions. Optimization and simplification of the original sludge corrosion process design is described and the use of transportable and reusable equipment is indicated. The processes and techniques described in the paper are shown to have wide applicability to nuclear cleanup.

  1. Influence of sternal size and inadvertent paramedian sternotomy on stability of the closure site: a clinical and mechanical study.

    Science.gov (United States)

    Zeitani, J; Penta de Peppo, A; Moscarelli, M; Guerrieri Wolf, L; Scafuri, A; Nardi, P; Nanni, F; Di Marzio, E; De Vico, P; Chiariello, L

    2006-07-01

    The influence of sternal size and of inadvertent paramedian sternotomy on stability of the closure site is not well defined. Data on 171 consecutive patients undergoing cardiac surgery through a midline sternotomy were prospectively collected. Intraoperative measurements of sternal dimension included thickness and width at the manubrium, the third and fifth intercostal spaces; paramedian sternotomy was defined as width of one side of the sternum equaling 75% or more of the entire width, at any of the three levels. The chest was closed with simple peristernal steel wires and inspected to detect deep wound infection and/or instability for 3 postoperative months. The sternal factors and several patient/surgery-related factors were included in a multivariate analysis model to identify factors affecting stability. An electromechanical traction test was conducted on 6 rewired sternal models after midline or paramedian sternotomy and separation data were analyzed. Chest instability was detected in 12 (7%) patients and wound infection in 2 (1.2%). Patient weight (P = .03), depressed left ventricular function (P = .04), sternum thickness (indexed to body weight, P = .03), and paramedian sternotomy (P = .0001) were risk factors of postoperative instability; paramedian sternotomy was the only independent predictor (P = .001). The electromechanical test showed more lateral displacement of the two rewired sternal halves after paramedian than midline sternotomy (P = .002); accordingly, load at fracture point was lower after paramedian sternotomy (220 +/- 20 N vs 545 +/- 25 N, P = 0.001). Inadvertent paramedian sternomoty strongly affects postoperative chest wound stability independently from sternal size, requiring prompt reinforcement of chest closure.

  2. Research in Support of Remediation Activities at the Savannah River Site

    International Nuclear Information System (INIS)

    Seaman, J.C.; B.B. Looney and M.K. Harris

    2007-01-01

    The USDOE Savannah River Site (SRS), an 803-km 2 (310-mile 2 ) facility located south of Aiken, SC on the upper Atlantic Coastal Plain and bounded to the west by the Savannah River, was established in the 1950s for the production and refinement of nuclear materials. To fulfill this mission during the past 50 years SRS has operated five nuclear reactors, two large chemical separation areas, waste disposal facilities (landfills, waste ponds, waste tanks, and waste stabilization), and a large number of research and logistics support facilities. Contaminants of concern (COC) resulting from site operations include chlorinated solvents, radionuclides, metals, and metalloids, often found as complex mixtures that greatly complicate remediation efforts when compared with civilian industries. The objective of this article is to provide a description of the lithology and hydrostratigraphy of the SRS, as well as a brief history of site operations and research activities as a preface to the current special section of Vadose Zone Journal (VZJ) dedicated to SRS, focusing mainly on issues that are unique to the USDOE complex. Contributions to the special section reflect a diverse range of topics, from hydrologic tracer experiments conducted both within the vadose and saturated zones to studies specifically aimed at identifying geochemical processes controlling the migration and partitioning of specific contaminants (e.g., TCE, 137 Cs, U, and Pu) in SRS subsurface environments. Addressing the diverse environmental challenges of the SRS provides a unique opportunity to conduct both fundamental and applied research across a range of experimental scales. Hence, the SRS has been a pioneering force in several areas of environmental research and remediation, often through active interdisciplinary collaboration with researchers from other USDOE facilities, academic and federal institutions, and commercial entities

  3. Site characterization activities at Stripa and other Swedish projects

    International Nuclear Information System (INIS)

    Ahlstroehm, P.E.

    1991-01-01

    The Swedish research programme concerning spent nuclear fuel disposal aims for submitting a siting license application around the year 2000. An important step towards that goal will be the detailed characterization of at least two potential sites in late 1990s. In preparation for such characterization several research projects are conducted. One is the international Stripa Project that includes a site characterization and validation project for a small size granite rock body. The Stripa work also includes further development of instrumentation and measurement techniques. Another project is the Finnsjoen Fracture Zone Project, which is characterizing a subhorizontal zone at depths from 100 to 350 meters. The third project is the new Swedish Hard Rock Laboratory planned at the site of the Oskarshamn nuclear power plant. The preinvestigations and construction of this laboratory include major efforts in development, application and validation of site characterization methodology. (author) 6 figs., 9 refs

  4. NOx reduction over metal-ion exchanged novel zeolite under lean conditions. Activity and hydrothermal stability

    International Nuclear Information System (INIS)

    Subbiah, Ayyappan; Gujar, Amit; Price, Geoffrey L.; Cho, Byong K.; Blint, Richard J.; Yie, Jae E.

    2003-01-01

    Zeolite SUZ-4 was synthesized and tested for its hydrothermal stability using a standard aging procedure coupled with NMR spectroscopy, and was identified as a promising support for lean-NO x catalysts for high temperature applications. Various metals such as Cu, Ag, Fe, Co were ion exchanged onto the SUZ-4 zeolite, and their catalytic activity for NO/NO x conversion was measured in the presence of excess oxygen using ethylene as the reducing agent. Among the metal-ions exchanged, copper proved to be the best metal cation for lean-NO x catalysis with the optimum level of exchange at 29-42%. The optimized, fresh Cu/SUZ-4 catalyst achieved 70-80% of NO/NO x conversion activity over a wide range of temperature from 350 to 600C with the maximum conversion temperature at 450C. The presence of H 2 O and SO 2 reduced the NO/NO x conversion by about 30% of the fresh Cu/SUZ-4 catalyst due possibly to the blocking of active sites for NO/NO x adsorption. Substitution of gasoline vapor for ethylene as the reductant improved the NO x reduction activity of the fresh Cu/SUZ-4 catalyst at high temperatures above 350C. Aging the Cu/SUZ-4 catalyst resulted in a slight shift of activity profile toward higher temperatures, yielding an increase of NO conversion by 16% and a decrease of NO x conversion by 15% at 525C. The effect of H 2 O and SO 2 on the aged catalyst was to reduce the NO activity by 20% and NO x activity by 30% at 500C. The effect of space velocity change was not significant except in the low temperature range where the reaction light-off occurs. Adsorption/desorption measurements indicate that aging Cu/SUZ-4 results in partial migration/agglomeration of Cu particles in the pores thereby reducing the NO/NO x activity. Overall, the NO x conversion efficiency of Cu/SUZ-4, for both fresh and aged, is much better than the benchmark Cu/ZSM-5 in the presence of H 2 O and/or SO 2

  5. Using Carbohydrate Interaction Assays to Reveal Novel Binding Sites in Carbohydrate Active Enzymes

    DEFF Research Database (Denmark)

    Cockburn, Darrell; Wilkens, Casper; Dilokpimol, Adiphol

    2016-01-01

    Carbohydrate active enzymes often contain auxiliary binding sites located either on independent domains termed carbohydrate binding modules (CBMs) or as so-called surface binding sites (SBSs) on the catalytic module at a certain distance from the active site. The SBSs are usually critical...

  6. Heat activation and stability of amylases from Bacillus species | Ajayi ...

    African Journals Online (AJOL)

    Leitch and Collier sporulating Bacillus medium was used to isolate some strains of Bacillus species from soil, wastewater and food sources in Ibadan, Oyo State, Nigeria, by heat activation method. Heat treatment at 80oC allowed the growth of sporulating Bacillus species, in the culture sample source without other bacteria ...

  7. Stability of deep-sited smectite minerals in crystalline rock-chemical aspects

    International Nuclear Information System (INIS)

    Pusch, R.

    1983-03-01

    A recent survey of possible conditions and mechanisms of smectite alteration, with special respect to the Swedish concept of radioactive waste disposal, has shown that the charge change by replacement of tetrahedral Si by Al is the key mechanism of the only practically important alteration, namely that of smectite/illite conversion. If K is available in sufficient quantities it will be fixed and permanent conversion to the unwanted illite-type minerals is a fact; if not, the smectite will be beidellitelike with practically unchanged physico/mechanical properties. Heating to more than about 100degreeC is thought to be the cause of the charge change. One other process may be critical and that is cementation of various substances. A possible cementation mechanism, i.e. that of quartz precipitation, is very probably associated with the smectite/illite conversion. Practical examples of smectite alteration and survival under reasonably well documented geological conditions with respect to temperature and pressure are available, one being that of the Kinnekulle bentonites, another one, although less well known, being the smectitic clay beds in the Hoeganaes depression. Rather comprehensive core sampling was made at both sites and elemental and mineral analyses were conducted as well as microstructural studies. They support the hypothesis that practically important charge change through Si/Al replacement requires a temperature of more than 100degreeC, and that such replacement does not yield permanent lattice collapse unless K is available in sufficient quantities. The Hoeganaes case also serves as an example of drastic loss in plasticity and swelling potential by cementation of other precipitates than quartz, namely iron compounds. (author)

  8. Effects of supported metallocene catalyst active center multiplicity on antioxidant-stabilized ethylene homo- and copolymers

    KAUST Repository

    Atiqullah, Muhammad

    2014-10-09

    © 2014 Akadémiai Kiadó, Budapest, Hungary. A silica-supported bis(n-butylcyclopentadienyl) zirconium dichloride [( n BuCp)2ZrCl2] catalyst was synthesized. This was used to prepare an ethylene homopolymer and an ethylene-1-hexene copolymer. The active center multiplicity of this catalyst was modeled by deconvoluting the copolymer molecular mass distribution and chemical composition distribution. Five different active site types were predicted, which matched the successive self-nucleation and annealing temperature peaks. The thermo-oxidative melt stability, with and without Irganox 1010 and Irgafos 168, of the above polyethylenes was investigated using nonisothermal differential scanning calorimetric (DSC) experiments at 150 °C. This is a temperature that ensures complete melting of the samples and avoids the diffusivity of oxygen to interfere into polyethylene crystallinity and its thermo-oxidative melt degradation. The oxidation parameters such as onset oxidation temperature, induction period, protection factor, and S-factor were determined by combining theoretical modeling with the DSC experiments. Subsequently, these findings were discussed considering catalyst active center multiplicity and polymer microstructure, particularly average ethylene sequence length. Several insightful results, which have not been reported earlier in the literature, were obtained. The antioxidant effect, for each polymer, varied as (Irganox + Irgafos) ≈ Irganox > Irgafos > Neat polymer. The as-synthesized homopolymer turned out to be almost twice as stable as the corresponding copolymer. The antioxidant(s) in the copolymer showed higher antioxidant effectiveness (AEX) than those in the homopolymer. Irganox exhibited more AEX than Irgafos. To the best of our knowledge, such findings have not been reported earlier in the literature. However, mixed with Irganox or Irgafos, their melt oxidation stability was comparable. The homopolymer, as per the calculated S-factor, showed Irganox

  9. Structure-based stabilization of HIV-1 gp120 enhances humoral immune responses to the induced co-receptor binding site.

    Directory of Open Access Journals (Sweden)

    Barna Dey

    2009-05-01

    Full Text Available The human immunodeficiency virus type 1 (HIV-1 exterior envelope glycoprotein, gp120, possesses conserved binding sites for interaction with the primary virus receptor, CD4, and also for the co-receptor, generally CCR5. Although gp120 is a major target for virus-specific neutralizing antibodies, the gp120 variable elements and its malleable nature contribute to evasion of effective host-neutralizing antibodies. To understand the conformational character and immunogenicity of the gp120 receptor binding sites as potential vaccine targets, we introduced structure-based modifications to stabilize gp120 core proteins (deleted of the gp120 major variable regions into the conformation recognized by both receptors. Thermodynamic analysis of the re-engineered core with selected ligands revealed significant stabilization of the receptor-binding regions. Stabilization of the co-receptor-binding region was associated with a marked increase in on-rate of ligand binding to this site as determined by surface plasmon resonance. Rabbit immunization studies showed that the conformational stabilization of core proteins, along with increased ligand affinity, was associated with strikingly enhanced humoral immune responses against the co-receptor-binding site. These results demonstrate that structure-based approaches can be exploited to stabilize a conformational site in a large functional protein to enhance immunogenic responses specific for that region.

  10. ALD Functionalized Nanoporous Gold: Thermal Stability, Mechanical Properties, and Catalytic Activity

    Energy Technology Data Exchange (ETDEWEB)

    Biener, M M; Biener, J; Wichmann, A; Wittstock, A; Baumann, T F; Baeumer, M; Hamza, A V

    2011-03-24

    Nanoporous metals have many technologically promising applications but their tendency to coarsen limits their long-term stability and excludes high temperature applications. Here, we demonstrate that atomic layer deposition (ALD) can be used to stabilize and functionalize nanoporous metals. Specifically, we studied the effect of nanometer-thick alumina and titania ALD films on thermal stability, mechanical properties, and catalytic activity of nanoporous gold (np-Au). Our results demonstrate that even only one-nm-thick oxide films can stabilize the nanoscale morphology of np-Au up to 1000 C, while simultaneously making the material stronger and stiffer. The catalytic activity of np-Au can be drastically increased by TiO{sub 2} ALD coatings. Our results open the door to high temperature sensor, actuator, and catalysis applications and functionalized electrodes for energy storage and harvesting applications.

  11. Voltage stability in low voltage microgrids in aspects of active and reactive power demand

    Directory of Open Access Journals (Sweden)

    Parol Mirosław

    2016-03-01

    Full Text Available Low voltage microgrids are autonomous subsystems, in which generation, storage and power and electrical energy consumption appear. In the paper the main attention has been paid to the voltage stability issue in low voltage microgrid for different variants of its operation. In the introduction a notion of microgrid has been presented, and also the issue of influence of active and reactive power balance on node voltage level has been described. Then description of voltage stability issue has been presented. The conditions of voltage stability and indicators used to determine voltage stability margin in the microgrid have been described. Description of the low voltage test microgrid, as well as research methodology along with definition of considered variants of its operation have been presented further. The results of exemplary calculations carried out for the daily changes in node load of the active and reactive power, i.e. the voltage and the voltage stability margin indexes in nodes have been presented. Furthermore, the changes of voltage stability margin indexes depending on the variant of the microgrid operation have been presented. Summary and formulation of conclusions related to the issue of voltage stability in microgrids have been included at the end of the paper.

  12. A Surface-Coupled Optical Trap with 1-bp Precision via Active Stabilization.

    Science.gov (United States)

    Okoniewski, Stephen R; Carter, Ashley R; Perkins, Thomas T

    2017-01-01

    Optical traps can measure bead motions with Å-scale precision. However, using this level of precision to infer 1-bp motion of molecular motors along DNA is difficult, since a variety of noise sources degrade instrumental stability. In this chapter, we detail how to improve instrumental stability by (1) minimizing laser pointing, mode, polarization, and intensity noise using an acousto-optical-modulator mediated feedback loop and (2) minimizing sample motion relative to the optical trap using a three-axis piezo-electric-stage mediated feedback loop. These active techniques play a critical role in achieving a surface stability of 1 Å in 3D over tens of seconds and a 1-bp stability and precision in a surface-coupled optical trap over a broad bandwidth (Δf = 0.03-2 Hz) at low force (6 pN). These active stabilization techniques can also aid other biophysical assays that would benefit from improved laser stability and/or Å-scale sample stability, such as atomic force microscopy and super-resolution imaging.

  13. Optimisation of activity and storage stability of crude pepsin ...

    African Journals Online (AJOL)

    Clearing of the extract by centrifugation at 3000g/15 min gave an extract with 902.3 PU/ml. Clarification by use of di-sodium phosphate (Na2HSO4) gave extract of 1679.1 PU/ml. The enzyme activity of the extract stored under deep freezer temperature was sibnificantly higher (p < 0.05) than ambient and refrigeration ...

  14. Vascular nanomedicine: Site specific delivery of elastin stabilizing therapeutics to damaged arteries

    Science.gov (United States)

    Sinha, Aditi

    improved resistance to elastolytic digestion. We further show that the same polyphenols interact with monomeric tropoelastin released by the vascular cells and dramatically increasing their self-assembly in-vitro. In addition, we demonstrate the elastogenic ability of these polyphenols in aiding the crosslinking of tropoelastin released by aneurysmal cells converting it into mature elastin. Finally, we developed a nanoparticle system functionalized with elastin antibody on the surface that, upon systemic delivery, can recognize and bind to sites of damaged elastin in the aorta. We are able to show that this nanoparticle system works in representative animal models for MAC and AAA. These nanoparticles demonstrated spatial and functional specificity for degraded elastin. In conclusion, our work is focused on understanding the role of elastin degradation in vascular calcification and aortic aneurysms. We tested approaches to halt elastin degradation and to regenerate elastin in arteries so that homeostasis can be achieved.

  15. Electronic metal-support interaction enhanced oxygen reduction activity and stability of boron carbide supported platinum

    Science.gov (United States)

    Jackson, Colleen; Smith, Graham T.; Inwood, David W.; Leach, Andrew S.; Whalley, Penny S.; Callisti, Mauro; Polcar, Tomas; Russell, Andrea E.; Levecque, Pieter; Kramer, Denis

    2017-06-01

    Catalysing the reduction of oxygen in acidic media is a standing challenge. Although activity of platinum, the most active metal, can be substantially improved by alloying, alloy stability remains a concern. Here we report that platinum nanoparticles supported on graphite-rich boron carbide show a 50-100% increase in activity in acidic media and improved cycle stability compared to commercial carbon supported platinum nanoparticles. Transmission electron microscopy and x-ray absorption fine structure analysis confirm similar platinum nanoparticle shapes, sizes, lattice parameters, and cluster packing on both supports, while x-ray photoelectron and absorption spectroscopy demonstrate a change in electronic structure. This shows that purely electronic metal-support interactions can significantly improve oxygen reduction activity without inducing shape, alloying or strain effects and without compromising stability. Optimizing the electronic interaction between the catalyst and support is, therefore, a promising approach for advanced electrocatalysts where optimizing the catalytic nanoparticles themselves is constrained by other concerns.

  16. Electronic metal-support interaction enhanced oxygen reduction activity and stability of boron carbide supported platinum.

    Science.gov (United States)

    Jackson, Colleen; Smith, Graham T; Inwood, David W; Leach, Andrew S; Whalley, Penny S; Callisti, Mauro; Polcar, Tomas; Russell, Andrea E; Levecque, Pieter; Kramer, Denis

    2017-06-22

    Catalysing the reduction of oxygen in acidic media is a standing challenge. Although activity of platinum, the most active metal, can be substantially improved by alloying, alloy stability remains a concern. Here we report that platinum nanoparticles supported on graphite-rich boron carbide show a 50-100% increase in activity in acidic media and improved cycle stability compared to commercial carbon supported platinum nanoparticles. Transmission electron microscopy and x-ray absorption fine structure analysis confirm similar platinum nanoparticle shapes, sizes, lattice parameters, and cluster packing on both supports, while x-ray photoelectron and absorption spectroscopy demonstrate a change in electronic structure. This shows that purely electronic metal-support interactions can significantly improve oxygen reduction activity without inducing shape, alloying or strain effects and without compromising stability. Optimizing the electronic interaction between the catalyst and support is, therefore, a promising approach for advanced electrocatalysts where optimizing the catalytic nanoparticles themselves is constrained by other concerns.

  17. Effect of polyols on the conformational stability and biological activity of a model protein lysozyme

    OpenAIRE

    Singh, Somnath; Singh, Jagdish

    2003-01-01

    The purpose of this study was to investigate the stabilizing action of polyols against various protein degradation mechanisms (eg, aggregation, deamidation, oxidation), using a model protein lysozyme. Differential scanning calorimeter (DSC) was used to measure the thermodynamic parameters, mid point transition temperature and calorimetric enthalpy, in order to evaluate conformational stability. Enzyme activity assay was used to corroborate the DSC results. Mannitol, sucrose, lactose, glycerol...

  18. Poly(ethylene glycol)-mediated conformational alteration of α-chymotrypsin prevents inactivation of insulin by stabilizing active intermediates.

    Science.gov (United States)

    Yu, Jibing; Wei, Xiuli; Zhang, Li; Fang, Xiaocui; Yang, Tao; Huang, Feng; Liang, Wei

    2014-10-06

    Proteolytic enzymes in the gut represent one of the biggest barriers against oral delivery of therapeutic proteins and peptides. In the current study, we explored the effect of poly(ethylene glycol) 400 (PEG 400), a commonly used crowding agent, on insulin degradation mediated by α-chymotrypsin (α-CT). Without PEG 400, insulin was quickly cleaved by α-CT to generate inactive degradation products. In comparison, incorporation of PEG 400 resulted in reaction mixtures with retained biological activity. The analysis on the conformation of α-CT and the local environment of the enzyme's active site unraveled that PEG 400 altered the conformation of α-CT to prevent the inactivation of insulin via stabilization of active intermediates. These findings indicated that PEG 400 may provide a promising addition toward oral delivery of insulin.

  19. Biogeochemical Cycling and Environmental Stability of Pu Relevant to Long-Term Stewardship of DOE Sites

    Energy Technology Data Exchange (ETDEWEB)

    Honeyman, Bruce D.

    2006-06-01

    The overall objective of this proposed research is to understand the biogeochemical cycling of Pu in environments of interest to long-term DOE stewardship issues. Central to Pu cycling (transport initiation to immobilization) is the role of microorganisms. The hypothesis underlying this proposal is that microbial activity is the causative agent in initiating the mobilization of Pu in near-surface environments: through the transformation of Pu associated with solid phases, production of extracellular polymeric substances (EPS) carrier phases, and the creation of microenvironments. Also, microbial processes are central to the immobilization of Pu species, through the metabolism of organically complexed Pu species and Pu associated with extracellular carrier phases and the creation of environments favorable for Pu transport retardation.

  20. Biogeochemical Cycling and Environmental Stability of Pu Relevant to Long-Term Stewardship of DOE Sites

    Energy Technology Data Exchange (ETDEWEB)

    Francis, Arokiasamy J.; Santschi, Peter H.; Honeyman, Bruce D.

    2005-06-01

    The overall objective of this proposed research is to understand the biogeochemical cycling of Pu in environments of interest to long-term DOE stewardship issues. Central to Pu cycling (transport initiation to immobilization) is the role of microorganisms. The hypothesis underlying this proposal is that microbial activity is the causative agent in initiating the mobilization of Pu in near-surface environments: through the transformation of Pu associated with solid phases, production of extracellular polymeric substances (EPS) carrier phases, and the creation of microenvironments. Also, microbial processes are central to the immobilization of Pu species, through the metabolism of organically complexed Pu species and Pu associated with extracellular carrier phases and the creation of environments favorable for Pu transport retardation.

  1. Influence of ozonation on COD in stabilized landfill leachate: Case study at Alor Pongsu landfill site, Perak

    Science.gov (United States)

    Zakaria, Siti Nor Farhana; Aziz, Hamidi Abdul

    2017-10-01

    One of an anaerobic stabilized landfill leachate in Malaysia underwent ozonation process. The sample rich in chemical oxygen demand (COD) was collected from Alor Pongsu Landfill Site, Perak (APLS). This site has been operating since year 2000. The leachate also contains other pollutants that exceeded the standard discharge limit for wastewater effluents. The effectiveness of ozone (O3) dosage, pH variation, and reaction time during ozonation was evaluated to measure the performance of O3 and determine the maximum operational conditions for this treatment. The maximum removal efficiency for COD was 50% at an ozone dosage of 31 g/m3, natural of pH 8.5, and reaction time of 60 min. The biodegradability ratio (BOD5/COD) improved from 0.08 to 0.23 after treatment with O3. The ozonation method has enhanced the biodegradability ratio and resulted high percentage removal of COD. This improvement showed that oxidation has a great potential to remediate recalcitrant pollutant wastes, such as landfill leachate.

  2. Complexation of trivalent lanthanide cations by different chelation sites of malic and tartric acid (composition, stability and probable structure

    Directory of Open Access Journals (Sweden)

    Mohammed Riri

    2016-11-01

    Full Text Available The formation of colorless gadolinium complexes (x,y,z between x gadolinium ions, y ligands and z protons of some organic acids has been studied in aqueous solution. In this work we shall present the results of investigations on the interaction of the gadolinium ion (Gd3+ with different chelation sites of malic and tartric acid formed in dilute solution for pH values between 5.50 and 7.50. The structures of these new organometallic complexes are Gd3(C4H4O52·(NO33·nH2O and Gd3(C4H4O62·(NO33·nH2O (C4H4O52-: malate ions and C4H4O62-: tartrate ions. These colorless gadolinium complexes of malate and tartrate ions have no absorption band UV–visible, the indirect photometry detection (IPD study; have identified major tri-nuclear complexes of these dicarboxylic acids, giving for these colorless complexes a (3,2,2 and (3,2,3, respectively. Composition and apparent stability constant depends on the acidity of the medium. To complement previous results and to propose probable structures for these new complexes detected in solution FT-IR and FT-Raman spectroscopy have been conducted to identify the different chelation sites for both ligands.

  3. Prevalence and Stability of Active Play, Restricted Movement and Television Viewing in Infants

    Science.gov (United States)

    Hesketh, Kylie D.; Crawford, David A.; Abbott, Gavin; Campbell, Karen J.; Salmon, Jo

    2015-01-01

    This study describes engagement in and stability of physical activity and sedentary behaviours in early life, and assesses associations with sex, maternal education and developmental stage. Maternal-report data at child age 4, 9 and 20 months were collected from 542 families in the Melbourne Infant Feeding Activity and Nutrition Trial Program.…

  4. Influence of Soil Humic and Fulvic Acid on the Activity and Stability of Lysozyme and Urease

    NARCIS (Netherlands)

    Li, Yan; Tan, WenFeng; Koopal, Luuk K.; Wang, MingXia; Liu, Fan; Norde, Willem

    2013-01-01

    Humic substances (HS), including humic acids (HA) and fulvic acids (FA), are important components of soil systems. HS form strong complexes with oppositely charged proteins, which will lead to changes in the enzyme activity. The effect of soil HS on the activity and stability of two enzymes was

  5. Influence of soil humic and fulvic acid on the activity and stability of lysozyme and urease

    NARCIS (Netherlands)

    Li, Y.; Tan, W.; Koopal, L.K.; Wang, M.; Liu, Fan; Norde, W.

    2013-01-01

    Humic substances (HS), including humic acids (HA) and fulvic acids (FA), are important components of soil systems. HS form strong complexes with oppositely charged proteins, which will lead to changes in the enzyme activity. The effect of soil HS on the activity and stability of two enzymes was

  6. Temporal stability and drivers of change in cardiac autonomic nervous system activity

    NARCIS (Netherlands)

    Hu, Mandy Xian; Lamers, Femke; Penninx, Brenda W J H; de Geus, Eco J C

    2017-01-01

    OBJECTIVES: This study determined temporal stability of ambulatory measured cardiac autonomic activity for different time periods and investigated potential drivers of changes in this activity. METHODS: Data was drawn from baseline (n=2379), 2-year (n=2245), and 6-year (n=1876) follow-up from the

  7. Stability and phase transfer of catalytically active platinum nanoparticle suspensions

    Energy Technology Data Exchange (ETDEWEB)

    Sriram, Indira; Curtin, Alexandra E.; Chiaramonti, Ann N.; Cuchiaro, J. Hunter; Weidner, Andrew R.; Tingley, Tegan M.; Greenlee, Lauren F.; Jeerage, Kavita M., E-mail: jeerage@boulder.nist.gov [National Instrument of Standards and Technology, Applied Chemicals and Materials Division (United States)

    2015-05-15

    In this work, we present a robust synthesis protocol for platinum nanoparticles that yields a monomodal dispersion of particles that are approximately 100 nm in diameter. We determine that these particles are actually agglomerates of much smaller particles, creating a “raspberry” morphology. We demonstrate that these agglomerates are stable at room temperature for at least 8 weeks by dynamic light scattering. Furthermore, we demonstrate consistent electrocatalytic activity for methanol oxidation. Finally, we quantitatively explore the relationship between dispersion solvent and particle agglomeration; specifically, particles are found to agglomerate abruptly as solvent polarity decreases.

  8. Stability and phase transfer of catalytically active platinum nanoparticle suspensions

    International Nuclear Information System (INIS)

    Sriram, Indira; Curtin, Alexandra E.; Chiaramonti, Ann N.; Cuchiaro, J. Hunter; Weidner, Andrew R.; Tingley, Tegan M.; Greenlee, Lauren F.; Jeerage, Kavita M.

    2015-01-01

    In this work, we present a robust synthesis protocol for platinum nanoparticles that yields a monomodal dispersion of particles that are approximately 100 nm in diameter. We determine that these particles are actually agglomerates of much smaller particles, creating a “raspberry” morphology. We demonstrate that these agglomerates are stable at room temperature for at least 8 weeks by dynamic light scattering. Furthermore, we demonstrate consistent electrocatalytic activity for methanol oxidation. Finally, we quantitatively explore the relationship between dispersion solvent and particle agglomeration; specifically, particles are found to agglomerate abruptly as solvent polarity decreases

  9. [Effects of loess soil stabilization on Lolium perenne L. growth and root activity].

    Science.gov (United States)

    Liu, Yue-mei; Zhang, Xing-chang; Wang, Dan-dan

    2011-10-01

    Taking the loess soils with bulk density 1.2 g cm(-3), 1.3 g cm(-3), and 1.4 g cm(-3) from Ansai, Shaanxi Province as test objects, a pot experiment was conducted to study the effects of different amendment amount of soil stabilizer (EN-1 stabilizer) on the growth and root activity of ryegrass (Lolium perenne L.). Within the range of the bulk densities, the leaf chlorophyll content, root activity, root/shoot ratio, root biomass, and plant biomass of L. perenne all decreased with increasing soil bulk density, and were higher under the amendment of EN-1 stabilizer, as compared with the control. With increasing amendment amount of EN-1 stabilizer, the leaf chlorophyll content, root activity, root/shoot ratio, root biomass, and plant biomass had a trend of increased first and decreased then. Soil bulk density and stabilizer amendment amount had significant interactive effect on the root biomass and plant biomass. Overall, the values of the test indices were the highest under 1.3 g cm(-3) soil bulk density and 0.15% EN-1 stabilizer amendment amount.

  10. Disulfide bond within mu-calpain active site inhibits activity and autolysis.

    Science.gov (United States)

    Lametsch, René; Lonergan, Steven; Huff-Lonergan, Elisabeth

    2008-09-01

    Oxidative processes have the ability to influence mu-calpain activity. In the present study the influence of oxidation on activity and autolysis of mu-calpain was examined. Furthermore, LC-MS/MS analysis was employed to identify and characterize protein modifications caused by oxidation. The results revealed that the activity of mu-calpain is diminished by oxidation with H2O2 in a reversible manner involving cysteine and that the rate of autolysis of mu-calpain concomitantly slowed. The LC-MS/MS analysis of the oxidized mu-calpain revealed that the amino acid residues 105-133 contained a disulfide bond between Cys(108) and Cys(115). The finding that the active site cysteine in mu-calpain is able to form a disulfide bond has, to our knowledge, not been reported before. This could be part of a unique oxidation mechanism for mu-calpain. The results also showed that the formation of the disulfide bond is limited in the control (no oxidant added), and further limited in a concentration-dependent manner when beta-mercaptoethanol is added. However, the disulfide bond is still present to some extent in all conditions indicating that the active site cysteine is potentially highly susceptible to the formation of this intramolecular disulfide bond.

  11. Calpain 3 Is Activated through Autolysis within the Active Site and Lyses Sarcomeric and Sarcolemmal Components

    Science.gov (United States)

    Taveau, Mathieu; Bourg, Nathalie; Sillon, Guillaume; Roudaut, Carinne; Bartoli, Marc; Richard, Isabelle

    2003-01-01

    Calpain 3 (Capn3) is known as the skeletal muscle-specific member of the calpains, a family of intracellular nonlysosomal cysteine proteases. This enigmatic protease has many unique features among the calpain family and, importantly, mutations in Capn3 have been shown to be responsible for limb girdle muscular dystrophy type 2A. Here we demonstrate that the Capn3 activation mechanism is similar to the universal activation of caspases and corresponds to an autolysis within the active site of the protease. We undertook a search for substrates in immature muscle cells, as several lines of evidence suggest that Capn3 is mostly in an inactive state in muscle and needs a signal to be activated. In this model, Capn3 proteolytic activity leads to disruption of the actin cytoskeleton and disorganization of focal adhesions through cleavage of several endogenous proteins. In addition, we show that titin, a previously identified Capn3 partner, and filamin C are further substrates of Capn3. Finally, we report that Capn3 colocalizes in vivo with its substrates at various sites along cytoskeletal structures. We propose that Capn3-mediated cleavage produces an adaptive response of muscle cells to external and/or internal stimuli, establishing Capn3 as a muscle cytoskeleton regulator. PMID:14645524

  12. Biopolymer-stabilized Pt nanoparticles colloid: a highly active and recyclable catalyst for biphasic catalysis

    International Nuclear Information System (INIS)

    Wang, Yujia; Shen, Yueyue; Qiu, Yunfei; Zhang, Ting; Liao, Yang; Zhao, Shilin; Ma, Jun; Mao, Hui

    2016-01-01

    Noble metal nanoparticles are promising candidates to replace conventional bulk counterparts owing to their high activity and selectivity. To enable catalyst recovery, noble metal nanoparticles are often supported onto solid matrices to prepare heterogeneous catalyst. Although recycle of noble metal nanoparticles is realized by heterogenization, a loss of activity is usually encountered. In the present investigation, Pt nanoparticles with tunable particle size (1.85–2.80 nm) were facilely prepared by using polyphenols as amphiphilic stabilizers. The as-prepared Pt nanoparticles colloid solution could be used as highly active catalyst in aqueous–organic biphasic catalysis. The phenolic hydroxyls of polyphenols could constrain Pt nanoparticles in aqueous phase, and simultaneously, the aromatic scaffold of polyphenols ensured effective interactions between substrates and Pt nanoparticles. As a consequence, the obtained polyphenols-stabilized Pt nanoparticles exhibited high activity and cycling stability in biphasic hydrogenation of a series of unsaturated compounds. Compared with conventional heterogeneous Pt-C and Pt-Al 2 O 3 catalysts, polyphenols-stabilized Pt nanoparticles showed obvious advantage both in activity and cycling stability.

  13. Towards identifying the active sites on RuO2(110) in catalyzing oxygen evolution  

    DEFF Research Database (Denmark)

    Rao, Reshma R.; Kolb, Manuel J.; Halck, Niels Bendtsen

    2017-01-01

    on the coordinatively unsaturated Ru sites (CUS) and hydrogen adsorbed to the bridging oxygen sites. At potentials relevant to the oxygen evolution reaction (OER), an –OO species on the Ru CUS sites was detected, which was stabilized by a neighboring –OH group on the Ru CUS or bridge site. Combining potential...

  14. Stability investigation of an airfoil section with active flap control

    DEFF Research Database (Denmark)

    Bergami, Leonardo; Gaunaa, Mac

    2010-01-01

    This work presents a method to determine flutter and divergence instability limits for a two-dimensional (2-D) airfoil section fitted with an actively controlled trailing edge flap. This flap consists of a deformable trailing edge, which deformation is governed by control algorithms based...... on measurements of either heave displacement, local angle of attack or aerodynamic pressure difference measured over the airfoil. The purpose of the controlled deformable flap is to reduce fluctuations in the aerodynamic forces on the airfoil, which, according to recent studies, have a significant potential...... for fatigue load alleviation. The structural model of the 2-D airfoil section contains three degrees of freedom: heave translation, pitch rotation and flap deflection. A potential flow model provides the aerodynamic forces and their distribution. The unsteady aerodynamics are described using an indicial...

  15. Directed surfaces structures and interfaces for enhanced electrocatalyst activity, selectivity, and stability for energy conversion reactions

    Energy Technology Data Exchange (ETDEWEB)

    Jaramillo, Thomas F. [Stanford Univ., CA (United States). Dept. of Chemical Engineering. Shriram Center

    2016-04-20

    IrO3/IrOx catalyst significantly outperforms rutile IrO2 and RuO2, the only other OER catalysts to have reasonable stability and activity in acidic electrolyte, and in fact demonstrates the best activity for any known OER catalyst measured in either acidic or in alkaline electrolyte. For alkaline conditions we have demonstrated that the combined effect of cerium as a dopant and gold as a metal support, significantly enhances the OER activity of electrodeposited NiOx films. This NiCeOx-Au catalyst delivers high OER activity in alkaline media, and is among the most active OER electrocatalysts reported to date (Nature Energy, accepted 2016). These studies of new catalysts for the OER, both in acid and in base, are fundamental to enabling new technologies of interest for the DOE, including the production of sustainable fuels and chemicals. ORR: One method to significantly reduce the Pt loading in fuel cell devices is to increase the ORR activity of Pt based systems. To this end we have synthesized a high surface area supported meso-structured PtxNi alloy thin film with a double gyroid morphology that both exhibits high activity and stability for the ORR (submitted, 2016). We have furthermore developed a Ru-core, Pt-shell system that improves the per Pt site activity by more than a factor of 2 (ChemElectroChem, 2014). Further refinement, optimizing Pt-shell thickness and reducing particle sintering during processing, enabled us to obtain a mass activity that is 2 times higher than commercial Pt/C from TKK. These are important contributions to the DOE goal of reducing Pt loading since an improved understanding of how to increase mass activity and stability helps enable low Pt content fuel cells.

  16. Relating structural aspects of bimetallic Pt(3)Cr(1)/C nanoparticles to their electrocatalytic activity, stability, and selectivity in the oxygen reduction reaction.

    Science.gov (United States)

    Taufany, Fadlilatul; Pan, Chun-Jern; Chou, Hung-Lung; Rick, John; Chen, Yong-Siou; Liu, Din-Goa; Lee, Jyh-Fu; Tang, Mau-Tsu; Hwang, Bing-Joe

    2011-09-12

    Two methods were used to prepare bimetallic Pt(3)Cr(1)/C nanocatalysts with similar composition but different alloying extent (structure). We investigated how these differences in alloying extent affect the catalytic activity, stability and selectivity in the oxygen reduction reaction (ORR). One method, based on slow thermal decomposition of the Cr precursor at a rate that matches that of chemical reduction of the Pt precursor, allows fine control of the composition of the Pt(3)Cr(1)/C alloy, whereas the second approach, using the ethylene glycol method, results in considerable deviation (>25 %) from the projected composition. Consequently, these two methods lead to variations in the alloying extent that strongly influence the Pt d-band vacancy and the Pt electroactive surface area (Pt ESCA). This relationship was systematically evaluated by transmission electron microscopy, X-ray absorption near edge structure spectroscopy, and electrochemical analysis. The ORR activity depends on two effects that nullify each other, namely, the number of active Pt sites and their activity. The Pt-site activity is more dominant in governing the ORR activity. The selectivity of the nanocatalyst towards the ORR and the competitive methanol oxidation reaction (MOR) depend on these two effects acting in cooperation to give enhanced ORR activity with suppressed MOR. The number of active Pt sites is associated with the Pt ESCA value, while Pt-site activity is associated with the alloying extent and Pt d-band vacancy (electronic) effects. The presence of Cr atoms in Pt(3)Cr(1)/C enhances stability during electrochemical treatment. Overall, the Pt(3)Cr(1)/C catalyst prepared by controlled-composition synthesis was shown to be superior in ORR activity, selectivity and stability owing to its favorable alloying extent, Pt d-band vacancy, and Pt ESCA. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  17. Methanol Synthesis over Cu/ZnO/Al2O3: The Active Site in Industrial Catalysis

    Energy Technology Data Exchange (ETDEWEB)

    Behrens, Malte

    2012-03-28

    Unlike homogeneous catalysts, heterogeneous catalysts that have been optimized through decades are typically so complex and hard to characterize that the nature of the catalytically active site is not known. This is one of the main stumbling blocks in developing rational catalyst design strategies in heterogeneous catalysis. We show here how to identify the crucial atomic structure motif for the industrial Cu/ZnO/Al{sub 2}O{sub 3} methanol synthesis catalyst. Using a combination of experimental evidence from bulk-, surface-sensitive and imaging methods collected on real high-performance catalytic systems in combination with DFT calculations. We show that the active site consists of Cu steps peppered with Zn atoms, all stabilized by a series of well defined bulk defects and surface species that need jointly to be present for the system to work.

  18. Evaluation of Cavity Collapse and Surface Crater Formation at the Norbo Underground Nuclear Test in U8c, Nevada Nuclear Security Site, and the Impact on Stability of the Ground Surface

    Energy Technology Data Exchange (ETDEWEB)

    Pawloski, G A

    2012-06-18

    Lawrence Livermore National Laboratory (LLNL) Containment Program performed a review of nuclear test-related data for the Norbo underground nuclear test in U8c to assist in evaluating this legacy site as a test bed for application technologies for use in On-Site Inspections (OSI) under the Comprehensive Nuclear Test Ban Treaty. This request is similar to one made for the Salut site in U8c (Pawloski, 2012b). Review of the Norbo site is complicated because the test first exhibited subsurface collapse, which was not unusual, but it then collapsed to the surface over one year later, which was unusual. Of particular interest is the stability of the ground surface above the Norbo detonation point. Proposed methods for on-site verification include radiological signatures, artifacts from nuclear testing activities, and imaging to identify alteration to the subsurface hydrogeology due to the nuclear detonation. Aviva Sussman from the Los Alamos National Laboratory (LANL) has also proposed work at this site. Both proposals require physical access at or near the ground surface of specific underground nuclear test locations at the Nevada Nuclear Security Site (NNSS), formerly the Nevada Test Site (NTS), and focus on possible activities such as visual observation, multispectral measurements, and shallow and deep geophysical surveys.

  19. Human population and activities in Forsmark. Site description

    International Nuclear Information System (INIS)

    Miliander, Sofia; Punakivi, Mari; Kylaekorpi, Lasse; Rydgren, Bernt

    2004-12-01

    The Swedish Nuclear Fuel and Waste Management Co (SKB) is in the process of selecting a safe and environmentally acceptable location for a deep repository of radioactive waste. Two alternative locations are under investigation. These are Forsmark, Oesthammars kommun (kommun = municipality) and Simpevarp/Laxemar, Oskarshamns kommun. SKB has expressed the importance of describing the humans and their activities in these areas and therefore has this synthesis concerning the human population in Forsmark been produced.The description is a statistical synthesis, mainly based upon statistical data from SCB (Statistics Sweden) that has been collected, processed and analysed. The statistical data has not been verified through site inspections and interviews. When using statistical data, it is advisable to note that the data becomes more unreliable if the areas are small, with small populations.The data in this description is essential for future evaluations of the impact on the environment and its human population (Environmental Impact Assessments). The data is also important when modelling the potential flows of radio nuclides and calculating the risk of exposure in future safety assessments.The actual area for the study is in this report called 'the Forsmark area', an area of 19.5 km 2 near Forsmark nuclear power plant. The land use in the Forsmark area differs notably from the land use in Uppsala laen (laen = county). Only 0.04% of the total area is developed (built-up) compared to 4.9% in Uppsala laen and only 4% is agricultural land compared to 25% in the county. Furthermore, there are far more forest, wetlands and water areas in the Forsmark area. The forest area represents as much as 72.5% of the total area.The Forsmark area is uninhabited, and its surroundings are very sparsely populated. In 2002, the population density in Forsmark was 1.8 inhabitants per square kilometre, which was 24 times lower than in Uppsala laen. The population density in the parish has been

  20. Human population and activities in Forsmark. Site description

    Energy Technology Data Exchange (ETDEWEB)

    Miliander, Sofia; Punakivi, Mari; Kylaekorpi, Lasse; Rydgren, Bernt [SwedPower AB, Stockholm (Sweden)

    2004-12-01

    The Swedish Nuclear Fuel and Waste Management Co (SKB) is in the process of selecting a safe and environmentally acceptable location for a deep repository of radioactive waste. Two alternative locations are under investigation. These are Forsmark, Oesthammars kommun (kommun = municipality) and Simpevarp/Laxemar, Oskarshamns kommun. SKB has expressed the importance of describing the humans and their activities in these areas and therefore has this synthesis concerning the human population in Forsmark been produced.The description is a statistical synthesis, mainly based upon statistical data from SCB (Statistics Sweden) that has been collected, processed and analysed. The statistical data has not been verified through site inspections and interviews. When using statistical data, it is advisable to note that the data becomes more unreliable if the areas are small, with small populations.The data in this description is essential for future evaluations of the impact on the environment and its human population (Environmental Impact Assessments). The data is also important when modelling the potential flows of radio nuclides and calculating the risk of exposure in future safety assessments.The actual area for the study is in this report called 'the Forsmark area', an area of 19.5 km{sup 2} near Forsmark nuclear power plant. The land use in the Forsmark area differs notably from the land use in Uppsala laen (laen = county). Only 0.04% of the total area is developed (built-up) compared to 4.9% in Uppsala laen and only 4% is agricultural land compared to 25% in the county. Furthermore, there are far more forest, wetlands and water areas in the Forsmark area. The forest area represents as much as 72.5% of the total area.The Forsmark area is uninhabited, and its surroundings are very sparsely populated. In 2002, the population density in Forsmark was 1.8 inhabitants per square kilometre, which was 24 times lower than in Uppsala laen. The population density in the

  1. From phosphatases to vanadium peroxidases: a similar architecture of the active site

    NARCIS (Netherlands)

    Hemrika, W.; Renirie, R.; Dekker, H. L.; Barnett, P.; Wever, R.

    1997-01-01

    We show here that the amino acid residues contributing to the active sites of the vanadate containing haloperoxidases are conserved within three families of acid phosphatases; this suggests that the active sites of these enzymes are very similar. This is confirmed by activity measurements showing

  2. Enhancement of transglutaminase activity by NMR identification of its flexible residues affecting the active site.

    Science.gov (United States)

    Shimba, Nobuhisa; Shinohara, Mina; Yokoyama, Kei ichi; Kashiwagi, Tatsuki; Ishikawa, Kohki; Ejima, Daisuke; Suzuki, Ei ichiro

    2002-04-24

    Incorporation of inter- or intramolecular covalent cross-links into food proteins with microbial transglutaminase (MTG) improves the physical and textural properties of many food proteins, such as tofu, boiled fish paste, and sausage. By using nuclear magnetic resonance, we have shown that the residues exhibiting relatively high flexibility in MTG are localized in the N-terminal region; however, the N-terminal region influences the microenvironment of the active site. These results suggest that the N-terminal region is not of primary importance for the global fold, but influences the substrate binding. Therefore, in order to increase the transglutaminase activity, the N-terminal residues were chosen as candidates for site-directed replacement and deletion. We obtained several mutants with higher activity, del1-2, del1-3, and S2R. We propose a strategy for enzyme engineering targeted toward flexible regions involved in the enzymatic activity. In addition, we also briefly describe how the number of glutamine residues in a substrate protein can be increased by mixing more than two kinds of TGases with different substrate specificities.

  3. Promotion of activity and thermal stability of chloroperoxidase by trace amount of metal ions (M2+/M3+).

    Science.gov (United States)

    Li, Haiyun; Gao, Jinwei; Wang, Limin; Li, Xiaohong; Jiang, Yucheng; Hu, Mancheng; Li, Shuni; Zhai, Quanguo

    2014-03-01

    The effect of M(2+) (Zn(2+), Cu(2+), Cd(2+), Mn(2+), Pb(2+)) and M(3+) (Cr(3+), La(3+), Fe(3+), Ce(3+), Y(3+), Al(3+)) metal ions on the activity and thermal stability of chloroperoxidase (CPO) was investigated in this work. It was found that the lower concentration of metal ions was favorable to CPO activity whereas the higher concentration reversed the results. CPO activity could be increased to 116.4-127.1% in the presence of a trace amount of these M(2+)/M(3+) metal ions at a concentration range of 0-25 μmol L(-1) after 2 h of incubation at 25 °C. The activating effect of M(3+) is better than that of M(2+), and Cr(3+) was mostly efficient. The thermal stability of the enzyme was also improved significantly. Only 30.3% of CPO activity was retained at 50 °C whereas 82.6% of CPO activity was maintained in the presence of Cr(3+) after 2 h of incubation at the same temperature. The activation of CPO by metal ions at their low concentration was studied through intrinsic fluorescence, circular dichroism (CD), and UV-Vis spectra assay. A favorable environment around the active site was achieved in the presence of metal ions. Intrinsic fluorescence and CD spectra indicated that the α-helix structure of CPO was strengthened in metal ion-contained media. More exposure of the heme ring was achieved for easy access of the substrate, which was suggested by UV-Vis spectrum analysis. This strategy for enhancing CPO activity is very simple and useful. It will be favorable to the practical application of this enzyme.

  4. Modification to the Remedial Action Plan and site design for stabilization of the inactive uranium mill tailings site at Mexican Hat, Utah: Volume 1, Text, Attachments 1--6. Final report

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1989-01-01

    This document provides the modifications to the 1988 Remedial Action Plan (RAP) of the contaminated materials at the Monument Valley, Arizona, and Mexican Hat, Utah. The text detailing the modifications and attachments 1 through 6 are provided with this document. The RAP was developed to serve a two-fold purpose. It presents the activities proposed by the Department of Energy (DOE) to accomplish long-term stabilization and control of the residual radioactive materials (RRM) from Monument Valley, Arizona, and Mexican Hat, Utah, at the Mexican Hat disposal site. It also serves to document the concurrence of both the Navajo Nation and the Nuclear Regulatory Commission (NRC) in the remedial action. This agreement, upon execution by DOE and the Navajo Nation and concurrence by the NRC, becomes Appendix B of the Cooperative Agreement. This document has been structured to provide a comprehensive understanding of the remedial action proposed for the Monument Valley and Mexican Hat sites. It includes specific design and construction requirements for the remedial action. Pertinent information and data are included with reference given to the supporting documents.

  5. Uranium Plume Treatability Demonstration at the Hanford Site 300 Area: Development of Polyphosphate Remediation Technology for In-Situ Stabilization of Uranium - 8070

    International Nuclear Information System (INIS)

    Wellman, Dawn M.; Pierce, Eric M.; Richards, Emily L.; Fruchter, Jonathan S.; Vermeul, Vincent R.

    2008-01-01

    A groundwater plume containing uranium, originating from a combination of purposeful discharges of wastewater to cribs, trenches and ponds, along with some accidental leaks and spills during nuclear fuel fabrication activities, has persisted beneath the Hanford Site 300 Area for many years. Despite the cessation of uranium releases and the removal of shallow vadose zone source materials, the goal of less than 30 (micro)g/L has not been achieved within the anticipated 10-year time period. Polyphosphate technology has been demonstrated to delay the precipitation of phosphate phases for controlled in situ precipitation of stable phosphate phases to control the long-term fate of uranium. Precipitation occurs when polyphosphate compounds hydrolyze to yield the orthophosphate molecule. Based on the hydrolysis kinetics of the polyphosphate polymer, the amendment can be tailored to act as a time-released source of phosphate for lateral plume treatment, immediate and sustained remediation of dissolved uranium, and to preclude rapid precipitation which could result in a drastic change in hydraulic conductivity of the target aquifer. Critical to successful implementation of polyphosphate remediation technology is a site specific evaluation and optimization of multi-length polyphosphate amendment formulations. A multi-faceted approach has been taken to provide key fundamental science knowledge regarding optimization of the polyphosphate remedy through: (1) phosphorus-31 nuclear magnetic resonance to quantify the effects of Hanford groundwater and sediment on the degradation of inorganic phosphates, (2) static tests to quantify the kinetics, loading, and stability of apatite as a long-term sorbent for uranium, and (3) single-pass flow through testing to quantify the stability of autunite and apatite under relevant site conditions. Dynamic column tests were utilized to (1) optimize the composition of the polyphosphate formulation for the formation and emplacement of apatite and

  6. LONG-TERM STABILITY OF THE LOCAL GROUND CONTROL NETWORK AT THE CO-LOCATION SITE OF MEDICINA

    Science.gov (United States)

    Abbondanza, C.; Sarti, P.; Legrand, J.

    2009-12-01

    ITRF combinations rely on the availability of accurate tie vectors linking reference points of space geodetic techniques. Co-located instruments are assumed to move consistently and no local relative motion is taken into account. Instabilities may degrade the quality of the co-location itself and perturb the result of ITRF combinations. This work aims to determine the stability of the local ground control network at Medicina (Italy) with independent surveying methods. The observatory hosts a co-location between a VLBI telescope and two GPS antennas, MEDI and MSEL. It is located in the Po Plain where thick layers of clays are the prevalent soil characteristics. Hence, provision of long term stability of geodetic monuments is a challenge and monitoring their stability is an issue. MEDI and the VLBI station regularly contribute to the determination of ITRF, while MSEL is part of the EUREF network. A set of five tie vectors observations linking the VLBI and MEDI reference points was acquired between 2001 and 2007. It is our main tool for performing local deformation analysis. Additionally, the GPS time series of MEDI and MSEL were used to cross check and confirm the local instability detected by terrestrial methods. To achieve a rigorous and reliable investigation of the local stability, multi-epoch terrestrial observations were homogeneously processed according to common parameterizations in a consistent reference frame. Similarly, continuous GPS observations from MEDI and MSEL were analysed according to the new EPN reprocessing strategy in order to monitor the short baseline between MEDI and MSEL; to spotlight any change in its length. Both approaches confirm differential motions at the site which can be related to monument instabilities originated by the particularly unfavourable local geological setting and the inapt design of the monuments foundation. The monuments move non homogeneously at rates reaching up to 1.6 mm/year, this value being comparable to intra

  7. Respiration and enzymatic activities as indicators of stabilization of sewage sludge composting.

    Science.gov (United States)

    Nikaeen, Mahnaz; Nafez, Amir Hossein; Bina, Bijan; Nabavi, BiBi Fatemeh; Hassanzadeh, Akbar

    2015-05-01

    The objective of this work was to study the evolution of physico-chemical and microbial parameters in the composting process of sewage sludge (SS) with pruning wastes (PW) in order to compare these parameters with respect to their applicability in the evaluation of organic matter (OM) stabilization. To evaluate the composting process and organic matter stability, different microbial activities were compared during composting of anaerobically digested SS with two volumetric ratios, 1:1 and 3:1 of PW:SS and two aeration techniques including aerated static piles (ASP) and turned windrows (TW). Dehydrogenase activity, fluorescein diacetate hydrolysis, and specific oxygen uptake rate (SOUR) were used as microbial activity indices. These indices were compared with traditional parameters, including temperature, pH, moisture content, organic matter, and C/N ratio. The results showed that the TW method and 3:1 (PW:SS) proportion was superior to the ASP method and 1:1 proportion, since the former accelerate the composting process by catalyzing the OM stabilization. Enzymatic activities and SOUR, which reflect microbial activity, correlated well with temperature fluctuations. Based on these results it appears that SOUR and the enzymatic activities are useful parameters to monitor the stabilization of SS compost. Copyright © 2015 Elsevier Ltd. All rights reserved.

  8. Structure of protein O-mannose kinase reveals a unique active site architecture.

    Science.gov (United States)

    Zhu, Qinyu; Venzke, David; Walimbe, Ameya S; Anderson, Mary E; Fu, Qiuyu; Kinch, Lisa N; Wang, Wei; Chen, Xing; Grishin, Nick V; Huang, Niu; Yu, Liping; Dixon, Jack E; Campbell, Kevin P; Xiao, Junyu

    2016-11-23

    The 'pseudokinase' SgK196 is a protein O-mannose kinase (POMK) that catalyzes an essential phosphorylation step during biosynthesis of the laminin-binding glycan on α-dystroglycan. However, the catalytic mechanism underlying this activity remains elusive. Here we present the crystal structure of Danio rerio POMK in complex with Mg 2+ ions, ADP, aluminum fluoride, and the GalNAc-β3-GlcNAc-β4-Man trisaccharide substrate, thereby providing a snapshot of the catalytic transition state of this unusual kinase. The active site of POMK is established by residues located in non-canonical positions and is stabilized by a disulfide bridge. GalNAc-β3-GlcNAc-β4-Man is recognized by a surface groove, and the GalNAc-β3-GlcNAc moiety mediates the majority of interactions with POMK. Expression of various POMK mutants in POMK knockout cells further validated the functional requirements of critical residues. Our results provide important insights into the ability of POMK to function specifically as a glycan kinase, and highlight the structural diversity of the human kinome.

  9. A practical approach for computing the active site of the ribonucleoside hydrolase of E. coli encoded by rihC.

    Science.gov (United States)

    Farone, Anthony; Farone, Mary; Kline, Paul; Quinn, Terrance; Sinkala, Zachariah

    2010-01-01

    We predict the potential active and catalytic sites, the transition state and how it is stabilized, and the mechanism of rihC ribonucleoside hydrolase of E. coli. Our approach is based on well-known primary sequence analysis techniques. A canonically associated extreme value distribution is used to assess the significance of the prediction. Parameters for the extreme value distribution are computed directly from data. Our practical approach is consistent with known results in the literature. We obtain BLOSUM matrices in a way that is intrinsically tied to the data base, and we employ user-friendly techniques that should be applicable to a range of medically significant scenarios.

  10. Exponential stability of delayed and impulsive cellular neural networks with partially Lipschitz continuous activation functions.

    Science.gov (United States)

    Song, Xueli; Xin, Xing; Huang, Wenpo

    2012-05-01

    The paper discusses exponential stability of distributed delayed and impulsive cellular neural networks with partially Lipschitz continuous activation functions. By relative nonlinear measure method, some novel criteria are obtained for the uniqueness and exponential stability of the equilibrium point. Our method abandons usual assumptions on global Lipschitz continuity, boundedness and monotonicity of activation functions. Our results are generalization and improvement of some existing ones. Finally, two examples and their simulations are presented to illustrate the correctness of our analysis. Copyright © 2012 Elsevier Ltd. All rights reserved.

  11. Models for the active site in galactose oxidase: Structure, spectra ...

    Indian Academy of Sciences (India)

    The crystal structure of the enzyme reveals that the coordination geometry of mononuclear copper(II) ion is square pyramidal, with two histidine imidazoles, a tyrosinate, and either H2O (H 7.0) or acetate (from buffer, H 4.5) in the equatorial sites and a tyrosinate ligand weakly bound in the axial position. This paper ...

  12. Informations on the active site of palmito polyphenol oxidase.

    Science.gov (United States)

    Robert, C; Cadet, F; Rouch, C; Pabion, M

    1995-01-01

    pH studies of palmito polyphenol oxidase are carried out with either 4-methylcatechol or pyrogallol as substrates. The pH profile is independent of the nature of the substrates tested. The symmetrical behaviour and the very slight differences between the values obtained suggest the existence of only one site on the molecule for o-diphenol substrates.

  13. Analysis of cavern and well stability at the West Hackberry SPR site using a full-dome model.

    Energy Technology Data Exchange (ETDEWEB)

    Sobolik, Steven R. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2015-08-01

    This report presents computational analyses that simulate the structural response of caverns at the Strategic Petroleum Reserve (SPR) West Hackberry site. The cavern field comprises 22 caverns. Five caverns (6, 7, 8, 9, 11) were acquired from industry and have unusual shapes and a history dating back to 1946. The other 17 caverns (101-117) were leached according to SPR standards in the mid-1980s and have tall cylindrical shapes. The history of the caverns and their shapes are simulated in a three-dimensional geomechanics model of the site that predicts deformations, strains, and stresses. Future leaching scenarios corresponding to oil drawdowns using fresh water are also simulated by increasing the volume of the caverns. Cavern pressures are varied in the model to capture operational practices in the field. The results of the finite element model are interpreted to provide information on the current and future status of subsidence, well integrity, and cavern stability. The most significant results in this report are relevant to Cavern 6. The cavern is shaped like a bowl with a large ceiling span and is in close proximity to Cavern 9. The analyses predict tensile stresses at the edge of the ceiling during repressurization of Cavern 6 following workover conditions. During a workover the cavern is at low pressure to service a well. The wellhead pressures are atmospheric. When the workover is complete, the cavern is repressurized. The resulting elastic stresses are sufficient to cause tension around the edge of the large ceiling span. With time, these stresses relax to a compressive state because of salt creep. However, the potential for salt fracture and propagation exists, particularly towards Cavern 9. With only 200 feet of salt between the caverns, the operational consequences must be examined if the two caverns become connected. A critical time may be during a workover of Cavern 9 in part because of the operational vulnerabilities, but also because dilatant damage

  14. Quantum mechanics study of the hydroxyethylamines-BACE-1 active site interaction energies

    Science.gov (United States)

    Gueto-Tettay, Carlos; Drosos, Juan Carlos; Vivas-Reyes, Ricardo

    2011-06-01

    The identification of BACE-1, a key enzyme in the production of Amyloid-β (Aβ) peptides, generated by the proteolytic processing of amyloid precursor protein, was a major advance in the field of Alzheimer's disease as this pathology is characterized by the presence of extracellular senile plaques, mainly comprised of Aβ peptides. Hydroxyethylamines have demonstrated a remarkable potential, like candidate drugs, for this disease using BACE-1 as target. Density Functional Theory calculations were employed to estimate interaction energies for the complexes formed between the hydroxyethylamine derivated inhibitors and 24 residues in the BACE-1 active site. The collected data offered not only a general but a particular quantitative description that gives a deep insight of the interactions in the active site, showing at the same time how ligand structural variations affect them. Polar interactions are the major energetic contributors for complex stabilization and those ones with charged aspartate residues are highlighted, as they contribute over 90% of the total attractive interaction energy. Ligand-ARG296 residue interaction reports the most repulsive value and decreasing of the magnitude of this repulsion can be a key feature for the design of novel and more potent BACE-1 inhibitors. Also it was explained why sultam derivated BACE-1 inhibitors are better ones than lactam based. Hydrophobic interactions concentrated at S1 zone and other relevant repulsions and attractions were also evaluated. The comparison of two different theory levels (X3LYP and M062X) allowed to confirm the relevance of the detected interactions as each theory level has its own strength to depict the forces involved, as is the case of M062X which is better describing the hydrophobic interactions. Those facts were also evaluated and confirmed by comparing the quantitative trend, of selected ligand-residue interactions, with MP2 theory level as reference standard method for electrostatic plus

  15. Catalytic Activity and Stability of Oxides: The Role of Near-Surface Atomic Structures and Compositions

    KAUST Repository

    Feng, Zhenxing

    2016-05-05

    δ oxide thin films, and the physical origin of segregation is discussed in comparison with (La1–ySry)2CoO4±δ/La1–xSrxCo0.2Fe0.8O3−δ. Sr enrichment in many electrocatalysts, such as La1–xSrxMO3−δ (M = Cr, Co, Mn, or Co and Fe) and Sm1–xSrxCoO3, has been probed using alternative techniques, including low energy ion scattering, secondary ion mass spectrometry, and X-ray fluorescence-based methods for depth-dependent, element-specific analysis. We highlight a strong connection between cation segregation and electrocatalytic properties, because cation segregation enhances oxygen transport and surface oxygen exchange kinetics. On the other hand, the formation of cation-enriched secondary phases can lead to the blocking of active sites, inhibiting oxygen exchange. With help from density functional theory, the links between cation migration, catalyst stability, and catalytic activity are provided, and the oxygen p-band center relative to the Fermi level can be identified as an activity descriptor. Based on these findings, we discuss strategies to increase a catalyst’s activity while maintaining stability to design efficient, cost-effective electrocatalysts.

  16. Active Erk Regulates Microtubule Stability in H-ras-Transformed Cells

    Directory of Open Access Journals (Sweden)

    Rene E. Harrison

    2001-01-01

    Full Text Available Increasing evidence suggests that activated erk regulates cell functions, at least in part, by mechanisms that do not require gene transcription. Here we show that the map kinase, erk, decorates microtubules (MTs and mitotic spindles in both parental and mutant active rastransfected 10T1 /2 fibroblasts and MCF10A breast epithelial cells. Approximately 20% of total cellular erk decorated MTs in both cell lines. A greater proportion of activated erk was associated with MTs in the presence of mutant active H-ras than in parental cells. Activation of erk by the ras pathway coincided with a decrease in the stability of MT, as detected by a stability marker. The MKK1 inhibitor, PD98059 and transfection of a dominant negative MKK1 blocked ras-induced instability of MTs but did not modify the association of erk with MTs or affect MT stability of the parental cells. These results indicate that the subset of active erk kinase that associates with MTs contributes to their instability in the presence of a mutant active ras. The MT-associated subset of active erk likely contributes to the enhanced invasive and proliferative abilities of cells containing mutant active H-ras.

  17. Remedial Action Plan and Site Design for stabilization of the inactive Uranium Mill Tailings sites at Slick Rock, Colorado: Appendix C to Attachment 3, Calculations. Final

    International Nuclear Information System (INIS)

    1995-09-01

    This volume contains calculations for: Slick Rock processing sites background ground water quality; Slick Rock processing sites lysimeter water quality; Slick Rock processing sites on-site and downgradient ground water quality; Slick Rock disposal site background water quality; Burro Canyon disposal site, Slick Rock, Colorado, average hydraulic gradients and average liner ground water velocities in the upper, middle, and lower sandstone units of the Burro Canyon formation; Slick Rock--Burro Canyon disposal site, Burro Canyon pumping and slug tests--analyses; water balance and surface contours--Burro Canyon disposal cell; and analytical calculation of drawdown in a hypothetical well completed in the upper sandstone unit of the Burro Canyon formation

  18. Preliminary siting activities for new waste handling facilities at the Idaho National Engineering Laboratory

    Energy Technology Data Exchange (ETDEWEB)

    Taylor, D.D.; Hoskinson, R.L.; Kingsford, C.O.; Ball, L.W.

    1994-09-01

    The Idaho Waste Processing Facility, the Mixed and Low-Level Waste Treatment Facility, and the Mixed and Low-Level Waste Disposal Facility are new waste treatment, storage, and disposal facilities that have been proposed at the Idaho National Engineering Laboratory (INEL). A prime consideration in planning for such facilities is the selection of a site. Since spring of 1992, waste management personnel at the INEL have been involved in activities directed to this end. These activities have resulted in the (a) identification of generic siting criteria, considered applicable to either treatment or disposal facilities for the purpose of preliminary site evaluations and comparisons, (b) selection of six candidate locations for siting,and (c) site-specific characterization of candidate sites relative to selected siting criteria. This report describes the information gathered in the above three categories for the six candidate sites. However, a single, preferred site has not yet been identified. Such a determination requires an overall, composite ranking of the candidate sites, which accounts for the fact that the sites under consideration have different advantages and disadvantages, that no single site is superior to all the others in all the siting criteria, and that the criteria should be assigned different weighing factors depending on whether a site is to host a treatment or a disposal facility. Stakeholder input should now be solicited to help guide the final selection. This input will include (a) siting issues not already identified in the siting, work to date, and (b) relative importances of the individual siting criteria. Final site selection will not be completed until stakeholder input (from the State of Idaho, regulatory agencies, the public, etc.) in the above areas has been obtained and a strategy has been developed to make a composite ranking of all candidate sites that accounts for all the siting criteria.

  19. Preliminary siting activities for new waste handling facilities at the Idaho National Engineering Laboratory

    International Nuclear Information System (INIS)

    Taylor, D.D.; Hoskinson, R.L.; Kingsford, C.O.; Ball, L.W.

    1994-09-01

    The Idaho Waste Processing Facility, the Mixed and Low-Level Waste Treatment Facility, and the Mixed and Low-Level Waste Disposal Facility are new waste treatment, storage, and disposal facilities that have been proposed at the Idaho National Engineering Laboratory (INEL). A prime consideration in planning for such facilities is the selection of a site. Since spring of 1992, waste management personnel at the INEL have been involved in activities directed to this end. These activities have resulted in the (a) identification of generic siting criteria, considered applicable to either treatment or disposal facilities for the purpose of preliminary site evaluations and comparisons, (b) selection of six candidate locations for siting,and (c) site-specific characterization of candidate sites relative to selected siting criteria. This report describes the information gathered in the above three categories for the six candidate sites. However, a single, preferred site has not yet been identified. Such a determination requires an overall, composite ranking of the candidate sites, which accounts for the fact that the sites under consideration have different advantages and disadvantages, that no single site is superior to all the others in all the siting criteria, and that the criteria should be assigned different weighing factors depending on whether a site is to host a treatment or a disposal facility. Stakeholder input should now be solicited to help guide the final selection. This input will include (a) siting issues not already identified in the siting, work to date, and (b) relative importances of the individual siting criteria. Final site selection will not be completed until stakeholder input (from the State of Idaho, regulatory agencies, the public, etc.) in the above areas has been obtained and a strategy has been developed to make a composite ranking of all candidate sites that accounts for all the siting criteria

  20. One stone, two birds: silica nanospheres significantly increase photocatalytic activity and colloidal stability of photocatalysts

    Science.gov (United States)

    Rasamani, Kowsalya D.; Foley, Jonathan J., IV; Sun, Yugang

    2018-03-01

    Silver-doped silver chloride [AgCl(Ag)] nanoparticles represent a unique class of visible-light-driven photocatalysts, in which the silver dopants introduce electron-abundant mid-gap energy levels to lower the bandgap of AgCl. However, free-standing AgCl(Ag) nanoparticles, particularly those with small sizes and large surface areas, exhibit low colloidal stability and low compositional stability upon exposure to light irradiation, leading to easy aggregation and conversion to metallic silver and thus a loss of photocatalytic activity. These problems could be eliminated by attaching the small AgCl(Ag) nanoparticles to the surfaces of spherical dielectric silica particles with submicrometer sizes. The high optical transparency in the visible spectral region (400-800 nm), colloidal stability, and chemical/electronic inertness displayed by the silica spheres make them ideal for supporting photocatalysts and significantly improving their stability. The spherical morphology of the dielectric silica particles can support light scattering resonances to generate significantly enhanced electric fields near the silica particle surfaces, on which the optical absorption cross-section of the AgCl(Ag) nanoparticles is dramatically increased to promote their photocatalytic activity. The hybrid silica/AgCl(Ag) structures exhibit superior photocatalytic activity and stability, suitable for supporting photocatalysis sustainably; for instance, their efficiency in the photocatalytic decomposition of methylene blue decreases by only ˜9% even after ten cycles of operation.

  1. Manipulation of EphB2 regulatory motifs and SH2 binding sites switches MAPK signaling and biological activity.

    Science.gov (United States)

    Tong, Jiefei; Elowe, Sabine; Nash, Piers; Pawson, Tony

    2003-02-21

    Signaling by the Eph family of receptor tyrosine kinases (RTKs) is complex, because they can interact with a variety of intracellular targets, and can potentially induce distinct responses in different cell types. In NG108 neuronal cells, activated EphB2 recruits p120RasGAP, in a fashion that is associated with down-regulation of the Ras-Erk mitogen-activated kinase (MAPK) pathway and neurite retraction. To pursue the role of the Ras-MAPK pathway in EphB2-mediated growth cone collapse, and to explore the biochemical and biological functions of Eph receptors, we sought to re-engineer the signaling properties of EphB2 by manipulating its regulatory motifs and SH2 binding sites. An EphB2 mutant that retained juxtamembrane (JM) RasGAP binding sites but incorporated a Grb2 binding motif at an alternate RasGAP binding site within the kinase domain had little effect on basal Erk MAPK activation. In contrast, elimination of all RasGAP binding sites, accompanied by the addition of a Grb2 binding site within the kinase domain, led to an increase in phospho-Erk levels in NG108 cells following ephrin-B1 stimulation. Functional assays indicated a correlation between neurite retraction and the ability of the EphB2 mutants to down-regulate Ras-Erk MAPK signaling. These data suggest that EphB2 can be designed to repress, stabilize, or activate the Ras-Erk MAPK pathway by the manipulation of RasGAP and Grb2 SH2 domain binding sites and support the notion that Erk MAPK regulation plays a significant role in axon guidance. The behavior of EphB2 variants with mutations in the JM region and kinase domains suggests an intricate pattern of regulation and target recognition by Eph receptors.

  2. Identification of promiscuous ene-reductase activity by mining structural databases using active site constellations.

    Science.gov (United States)

    Steinkellner, Georg; Gruber, Christian C; Pavkov-Keller, Tea; Binter, Alexandra; Steiner, Kerstin; Winkler, Christoph; Lyskowski, Andrzej; Schwamberger, Orsolya; Oberer, Monika; Schwab, Helmut; Faber, Kurt; Macheroux, Peter; Gruber, Karl

    2014-06-23

    The exploitation of catalytic promiscuity and the application of de novo design have recently opened the access to novel, non-natural enzymatic activities. Here we describe a structural bioinformatic method for predicting catalytic activities of enzymes based on three-dimensional constellations of functional groups in active sites ('catalophores'). As a proof-of-concept we identify two enzymes with predicted promiscuous ene-reductase activity (reduction of activated C-C double bonds) and compare them with known ene-reductases, that is, members of the Old Yellow Enzyme family. Despite completely different amino acid sequences, overall structures and protein folds, high-resolution crystal structures reveal equivalent binding modes of typical Old Yellow Enzyme substrates and ligands. Biochemical and biocatalytic data show that the two enzymes indeed possess ene-reductase activity and reveal an inverted stereopreference compared with Old Yellow Enzymes for some substrates. This method could thus be a tool for the identification of viable starting points for the development and engineering of novel biocatalysts.

  3. Improvement of AEP Predictions Using Diurnal CFD Modelling with Site-Specific Stability Weightings Provided from Mesoscale Simulation

    Science.gov (United States)

    Hristov, Y.; Oxley, G.; Žagar, M.

    2014-06-01

    The Bolund measurement campaign, performed by Danish Technical University (DTU) Wind Energy Department (also known as RISØ), provided significant insight into wind flow modeling over complex terrain. In the blind comparison study several modelling solutions were submitted with the vast majority being steady-state Computational Fluid Dynamics (CFD) approaches with two equation k-epsilon turbulence closure. This approach yielded the most accurate results, and was identified as the state-of-the-art tool for wind turbine generator (WTG) micro-siting. Based on the findings from Bolund, further comparison between CFD and field measurement data has been deemed essential in order to improve simulation accuracy for turbine load and long-term Annual Energy Production (AEP) estimations. Vestas Wind Systems A/S is a major WTG original equipment manufacturer (OEM) with an installed base of over 60GW in over 70 countries accounting for 19% of the global installed base. The Vestas Performance and Diagnostic Centre (VPDC) provides online live data to more than 47GW of these turbines allowing a comprehensive comparison between modelled and real-world energy production data. In previous studies, multiple sites have been simulated with a steady neutral CFD formulation for the atmospheric surface layer (ASL), and wind resource (RSF) files have been generated as a base for long-term AEP predictions showing significant improvement over predictions performed with the industry standard linear WAsP tool. In this study, further improvements to the wind resource file generation with CFD are examined using an unsteady diurnal cycle approach with a full atmospheric boundary layer (ABL) formulation, with the unique stratifications throughout the cycle weighted according to mesoscale simulated sectorwise stability frequencies.

  4. Fe65 does not stabilize AICD during activation of transcription in a luciferase assay

    International Nuclear Information System (INIS)

    Huysseune, Sandra; Kienlen-Campard, Pascal; Octave, Jean-Noel

    2007-01-01

    The APP intracellular domain (AICD) could be involved in signaling via interaction with the adaptor protein Fe65, and with the histone acetyl transferase Tip60. However, the real function of AICD and Fe65 in regulation of transcription remains controversial. In this study, the human APPGal4 fusion protein was expressed in CHO cells and the transcriptional activity of AICDGal4 was measured in a luciferase-based reporter assay. AICDGal4 was stabilized by expression of Fe65 and levels of AICDGal4 controlled luciferase activity. On the contrary, when human APP was expressed in CHO cells, coexpression of Fe65 increased luciferase activity without affecting the amount of AICD fragment. AICD produced from APP was protected from degradation by orthophenanthroline, but not by lactacystine, indicating that AICD is not a substrate of the chymotryptic activity of the proteasome. It is concluded that Fe65 can control luciferase activity without stabilizing the labile AICD fragment

  5. Evaluating Chemical Reactivity And Mechanical Stability Of Nano Palladized Iron Embedded In Activated Carbon On Dechlorination Of Polychlorinated Biphenyls

    Science.gov (United States)

    Remediation of contaminated sites with hydrophobic organic compounds such as polychlorinated biphenyls (PCBs) remains a scientific and technical challenge. The high stability, low aqueous solubility, and high organic affinity of PCBs make them difficult to treat. Many physical,...

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

    Directory of Open Access Journals (Sweden)

    Pengyu Dong

    2016-11-01

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

  7. Enzyme Stability and Activity in Non-Aqueous Reaction Systems: A Mini Review

    Directory of Open Access Journals (Sweden)

    Shihui Wang

    2016-02-01

    Full Text Available Enormous interest in biocatalysis in non-aqueous phase has recently been triggered due to the merits of good enantioselectivity, reverse thermodynamic equilibrium, and no water-dependent side reactions. It has been demonstrated that enzyme has high activity and stability in non-aqueous media, and the variation of enzyme activity is attributed to its conformational modifications. This review comprehensively addresses the stability and activity of the intact enzymes in various non-aqueous systems, such as organic solvents, ionic liquids, sub-/super-critical fluids and their combined mixtures. It has been revealed that critical factors such as Log P, functional groups and the molecular structures of the solvents define the microenvironment surrounding the enzyme molecule and affect enzyme tertiary and secondary structure, influencing enzyme catalytic properties. Therefore, it is of high importance for biocatalysis in non-aqueous media to elucidate the links between the microenvironment surrounding enzyme surface and its stability and activity. In fact, a better understanding of the correlation between different non-aqueous environments and enzyme structure, stability and activity can contribute to identifying the most suitable reaction medium for a given biotransformation.

  8. Human population and activities at Simpevarp. Site description

    International Nuclear Information System (INIS)

    Miliander, Sofia; Punakivi, Mari; Kylaekorpi, Lasse; Rydgren, Bernt

    2004-12-01

    The Swedish Nuclear Fuel and Waste Management Co (SKB) is in the process of selecting a safe and environmentally acceptable location for a deep repository of radioactive waste. Two alternative locations are under investigation. These are Forsmark, Oesthammars kommun (kommun = municipality) and Simpevarp/Laxemar, Oskarshamns kommun. SKB has expressed the importance of describing the humans and their activities in these areas and therefore has this synthesis concerning the human population in Forsmark been produced. The description is a statistical synthesis, mainly based upon statistical data from SCB (Statistics Sweden) that has been collected, processed and analysed. The statistical data has not been verified through site inspections and interviews. When using statistical data, it is advisable to note that the data becomes more unreliable if the areas are small, with small populations. The data in this description is essential for future evaluations of the impact on the environment and its human population (environmental impacts assessments). The data is also important when modelling the potential flows of radio nuclides and calculating the risk of exposure in future safety assessments. The actual area for the study is in this report called 'the Simpevarp area', an area of 127.0 km 2 near Oskarshamn nuclear power plant. The land use in Simpevarp area differs notably from the land use in Kalmar laen. The forest area is far more dominating in Simpevarp area than in Kalmar laen and it represents as much as 89% compared to 63% of the total area. Only 4.4% of the area is arable land compared to 11.6% in Kalmar laen and only 0.3% is of other type (wetlands, bare rock, quarries, pites etc) compared to 15.6% in the county. The main observation is that Simpevarp area is a sparsely populated area located in a relatively lightly populated county. In 2002, the population density was 7.4 inhabitants/km 2 , three times lower than in Kalmar laen. The demography statistics show

  9. Human population and activities at Simpevarp. Site description

    Energy Technology Data Exchange (ETDEWEB)

    Miliander, Sofia; Punakivi, Mari; Kylaekorpi, Lasse; Rydgren, Bernt [SwedPower AB, Stockholm (Sweden)

    2004-12-01

    The Swedish Nuclear Fuel and Waste Management Co (SKB) is in the process of selecting a safe and environmentally acceptable location for a deep repository of radioactive waste. Two alternative locations are under investigation. These are Forsmark, Oesthammars kommun (kommun = municipality) and Simpevarp/Laxemar, Oskarshamns kommun. SKB has expressed the importance of describing the humans and their activities in these areas and therefore has this synthesis concerning the human population in Forsmark been produced. The description is a statistical synthesis, mainly based upon statistical data from SCB (Statistics Sweden) that has been collected, processed and analysed. The statistical data has not been verified through site inspections and interviews. When using statistical data, it is advisable to note that the data becomes more unreliable if the areas are small, with small populations. The data in this description is essential for future evaluations of the impact on the environment and its human population (environmental impacts assessments). The data is also important when modelling the potential flows of radio nuclides and calculating the risk of exposure in future safety assessments. The actual area for the study is in this report called 'the Simpevarp area', an area of 127.0 km{sup 2} near Oskarshamn nuclear power plant. The land use in Simpevarp area differs notably from the land use in Kalmar laen. The forest area is far more dominating in Simpevarp area than in Kalmar laen and it represents as much as 89% compared to 63% of the total area. Only 4.4% of the area is arable land compared to 11.6% in Kalmar laen and only 0.3% is of other type (wetlands, bare rock, quarries, pites etc) compared to 15.6% in the county. The main observation is that Simpevarp area is a sparsely populated area located in a relatively lightly populated county. In 2002, the population density was 7.4 inhabitants/km{sup 2}, three times lower than in Kalmar laen. The

  10. Early Site Permit Demonstration Program: Recommendations for communication activities and public participation in the Early Site Permit Demonstration Program

    International Nuclear Information System (INIS)

    1993-01-01

    On October 24, 1992, President Bush signed into law the National Energy Policy Act of 1992. The bill is a sweeping, comprehensive overhaul of the Nation's energy laws, the first in more than a decade. Among other provisions, the National Energy Policy Act reforms the licensing process for new nuclear power plants by adopting a new approach developed by the US Nuclear Regulatory Commission (NRC) in 1989, and upheld in court in 1992. The NRC 10 CFR Part 52 rule is a three-step process that guarantees public participation at each step. The steps are: early site permit approval; standard design certifications; and, combined construction/operating licenses for nuclear power reactors. Licensing reform increases an organization's ability to respond to future baseload electricity generation needs with less financial risk for ratepayers and the organization. Costly delays can be avoided because design, safety and siting issues will be resolved before a company starts to build a plant. Specifically, early site permit approval allows for site suitability and acceptability issues to be addressed prior to an organization's commitment to build a plant. Responsibility for site-specific activities, including communications and public participation, rests with those organizations selected to try out early site approval. This plan has been prepared to assist those companies (referred to as sponsoring organizations) in planning their communications and public involvement programs. It provides research findings, information and recommendations to be used by organizations as a resource and starting point in developing their own plans

  11. Early Site Permit Demonstration Program: Recommendations for communication activities and public participation in the Early Site Permit Demonstration Program

    Energy Technology Data Exchange (ETDEWEB)

    1993-01-27

    On October 24, 1992, President Bush signed into law the National Energy Policy Act of 1992. The bill is a sweeping, comprehensive overhaul of the Nation`s energy laws, the first in more than a decade. Among other provisions, the National Energy Policy Act reforms the licensing process for new nuclear power plants by adopting a new approach developed by the US Nuclear Regulatory Commission (NRC) in 1989, and upheld in court in 1992. The NRC 10 CFR Part 52 rule is a three-step process that guarantees public participation at each step. The steps are: early site permit approval; standard design certifications; and, combined construction/operating licenses for nuclear power reactors. Licensing reform increases an organization`s ability to respond to future baseload electricity generation needs with less financial risk for ratepayers and the organization. Costly delays can be avoided because design, safety and siting issues will be resolved before a company starts to build a plant. Specifically, early site permit approval allows for site suitability and acceptability issues to be addressed prior to an organization`s commitment to build a plant. Responsibility for site-specific activities, including communications and public participation, rests with those organizations selected to try out early site approval. This plan has been prepared to assist those companies (referred to as sponsoring organizations) in planning their communications and public involvement programs. It provides research findings, information and recommendations to be used by organizations as a resource and starting point in developing their own plans.

  12. SUMOylation of the Forkhead transcription factor FOXL2 promotes its stabilization/activation through transient recruitment to PML bodies.

    Directory of Open Access Journals (Sweden)

    Adrien Georges

    Full Text Available BACKGROUND: FOXL2 is a transcription factor essential for ovarian development and maintenance. It is mutated in the genetic condition called Blepharophimosis Ptosis Epicantus inversus Syndrome (BPES and in cases of isolated premature ovarian failure. We and others have previously shown that FOXL2 undergoes several post-translational modifications. METHODS AND PRINCIPAL FINDINGS: Here, using cells in culture, we show that interference with FOXL2 SUMOylation leads to a robust inhibition of its transactivation ability, which correlates with a decreased stability. Interestingly, FOXL2 SUMOylation promotes its transient recruitment to subnuclear structures that we demonstrate to be PML (Promyelocytic Leukemia Nuclear Bodies. Since PML bodies are known to be sites where post-translational modifications of nuclear factors take place, we used tandem mass spectrometry to identify new post-translational modifications of FOXL2. Specifically, we detected four phosphorylated, one sulfated and three acetylated sites. CONCLUSIONS: By analogy with other transcription factors, we propose that PML Nuclear Bodies might transiently recruit FOXL2 to the vicinity of locally concentrated enzymes that could be involved in the post-translational maturation of FOXL2. FOXL2 acetylation, sulfation, phosphorylation as well as other modifications yet to be discovered might alter the transactivation capacity of FOXL2 and/or its stability, thus modulating its global intracellular activity.

  13. Active-Site Hydration and Water Diffusion in Cytochrome P450cam: A Highly Dynamic Process

    Energy Technology Data Exchange (ETDEWEB)

    Miao, Yinglong [ORNL; Baudry, Jerome Y [ORNL

    2011-01-01

    Long-timescale molecular dynamics simulations (300 ns) are performed on both the apo- (i.e., camphor-free) and camphor-bound cytochrome P450cam (CYP101). Water diffusion into and out of the protein active site is observed without biased sampling methods. During the course of the molecular dynamics simulation, an average of 6.4 water molecules is observed in the camphor-binding site of the apo form, compared to zero water molecules in the binding site of the substrate-bound form, in agreement with the number of water molecules observed in crystal structures of the same species. However, as many as 12 water molecules can be present at a given time in the camphor-binding region of the active site in the case of apo-P450cam, revealing a highly dynamic process for hydration of the protein active site, with water molecules exchanging rapidly with the bulk solvent. Water molecules are also found to exchange locations frequently inside the active site, preferentially clustering in regions surrounding the water molecules observed in the crystal structure. Potential-of-mean-force calculations identify thermodynamically favored trans-protein pathways for the diffusion of water molecules between the protein active site and the bulk solvent. Binding of camphor in the active site modifies the free-energy landscape of P450cam channels toward favoring the diffusion of water molecules out of the protein active site.

  14. Diffusion-controlled reaction rates for two active sites on a sphere.

    Science.gov (United States)

    Shoup, David E

    2014-01-01

    The diffusion-limited reaction rate of a uniform spherical reactant is generalized to anisotropic reactivity. Previous work has shown that the protein model of a uniform sphere is unsatisfactory in many cases. Competition of ligands binding to two active sites, on a spherical enzyme or cell is studied analytically. The reaction rate constant is given for two sites at opposite ends of the species of interest. This is compared with twice the reaction rate for a single site. It is found that the competition between sites lowers the reaction rate over what is expected for two sites individually. Competition between sites does not show up, until the site half angle is greater than 30 degrees. Competition between sites is negligible until the site size becomes large. The competitive effect grows as theta becomes large. The maximum effect is given for theta = pi/2.

  15. Improvement of helicopter attitude stability by active control of the conventional swash plate

    Science.gov (United States)

    Ham, Norman D.

    1993-01-01

    The Final Report on improvement of helicopter attitude stability by active control of the conventional swash plate covering the period from Nov. 1986 to Dec. 1993 is presented. A paper on the history, principles, and applications of helicopter individual-blade-control is included.

  16. Effect of active arm swing to local dynamic stability during walking.

    Science.gov (United States)

    Wu, Yu; Li, Yue; Liu, An-Min; Xiao, Fei; Wang, Yin-Zhi; Hu, Fei; Chen, Jin-Ling; Dai, Ke-Rong; Gu, Dong-Yun

    2016-02-01

    Arm swing is an essential component in regulating dynamic stability of the whole body during walking, while the contribution of active arm swing to local dynamic stability of different motion segments remains unclear. This study investigated the effects of arm swing under natural arm swing condition and active arm swing condition on local dynamic stability and gait variability of the trunk segments (C7 and T10 joint) and lower extremity joints (hip, knee and ankle joint). The local divergence exponents (λs) and mean standard deviation over strides (MeanSD) of 24 young healthy adults were calculated while they were walking on treadmill with two arm swing conditions at their preferred walking speed (PWS). We found that in medial-lateral direction, both λs and MeanSD values of the trunk segments (C7 and T10 joint) in active arm swing condition were significantly lower than those in natural arm swing condition (parm swing conditions (p>0.05, respectively). In anterior-posterior and vertical direction, neither λs nor MeanSD values of all body segments showed significant difference between two arm swing conditions (p>0.05, respectively). These findings indicate that active arm swing may help to improve the local dynamic stability of the trunk segments in medial-lateral direction. Copyright © 2015 Elsevier B.V. All rights reserved.

  17. Activation and thermal stability of ultra-shallow B+-implants in Ge

    DEFF Research Database (Denmark)

    Yates, B. R.; Darby, B. L.; Petersen, Dirch Hjorth

    2012-01-01

    The activation and thermal stability of ultra-shallow B+ implants in crystalline (c-Ge) and preamorphized Ge (PA-Ge) following rapid thermal annealing was investigated using micro Hall effect and ion beam analysis techniques. The residual implanted dose of ultra-shallow B+ implants in Ge was char...

  18. Effect of different stabilizers on the antibacterial activity of “ginger ...

    African Journals Online (AJOL)

    The effect of five stabilizers i.e. citric acid, sodium metabisulfite, sodium benzoate, olive oil and ascorbic acid mixed in the ginger - garlic paste were evaluated against five pathogens (E.coli, Staphylococcus aureus, Salmonella typhi, Proteus mirabilis and Enterobacter aerogenes). Activity of the control paste decreased ...

  19. The Broadening of Activities in the Financial System : Implications for Financial Stability and Regulation

    NARCIS (Netherlands)

    Wagner, W.B.

    2006-01-01

    Conglomeration and consolidation in the financial system broaden the activities financial institutions are undertaking and cause them to become more homogenous.Although resulting diversification gains make each institution appear less risky, we argue that financial stability may not improve as total

  20. The use of indigenous plant species and calcium phosphate for the stabilization of highly metal-polluted sites in southern Poland

    NARCIS (Netherlands)

    Kucharski, R.; Sas-Nowosielska, A.; Malkowski, E.; Japenga, J.; Kuperberg, J.M.; Pogrzeba, M.; Krzyzak, J.

    2005-01-01

    Highly metal-polluted (Pb, Cd, Zn) soil from a non-ferrous mine and smelter site in southern Poland, further referred to as Waryski soil, was used to test indigenous plant species for stabilization effectiveness of heavy metals in soils. Results of pilot investigations with commercially available

  1. Calculations of axisymmetric stability of tokamak plasmas with active and passive feedback

    Energy Technology Data Exchange (ETDEWEB)

    Ward, D.J.; Jardin, S.C.; Cheng, C.Z.

    1991-07-01

    A new linear MHD stability code, NOVA-W, has been developed in order to study feedback stabilization of the axisymmetric mode in deformable tokamak plasmas. The NOVA-W code is a modification of the non-variational MHD stability code NOVA that includes the effects of resistive passive conductors and active feedback circuits. The vacuum calculation has been reformulated in terms of the perturbed poloidal flux to allow the inclusion of perturbed toroidal currents outside the plasma. The boundary condition at the plasma-vacuum interface relates the instability displacement to the perturbed poloidal flux. This allows a solution of the linear MHD stability equations with the feedback effects included. The passive stability predictions of the code have been tested both against a simplified analytic model and against a different numerical calculation for a realistic tokamak configuration. The comparisons demonstrate the accuracy of the NOVA-W results. Active feedback calculations are performed for the CIT tokamak design demonstrating the effect of varying the position of the flux loops that provide the measurements of vertical displacement. The results compare well with those computed earlier using a less efficient nonlinear code. 37 refs., 13 figs.

  2. Spatial patterns of microbial diversity and activity in an aged creosote-contaminated site

    OpenAIRE

    Mukherjee, Shinjini; Juottonen, Heli; Siivonen, Pauli; Lloret Quesada, Cosme; Tuomi, Pirjo; Pulkkinen, Pertti; Yrjälä, Kim

    2014-01-01

    Restoration of polluted sites via in situ bioremediation relies heavily on the indigenous microbes and their activities. Spatial heterogeneity of microbial populations, contaminants and soil chemical parameters on such sites is a major hurdle in optimizing and implementing an appropriate bioremediation regime. We performed a grid-based sampling of an aged creosote-contaminated site followed by geostatistical modelling to illustrate the spatial patterns of microbial diversity and activity and ...

  3. Assessment of former uranium sites and their ongoing remediation activities

    International Nuclear Information System (INIS)

    Khakimov, N.; Adkhamov, A.; Nazarov, Kh.M.; Mahmadov, T.; Mirsaidov, I.U.

    2012-01-01

    Carried out analysis on tailing's buildings operation shows that period for engineer barrier service, taking into account any catastrophic natural impacts, is too little in comparison with life-time of long-live radionuclides. Priorities should be defined by danger degree and isolation costs (protection optimization), therefore uncommon, non-traditional methods, developed taking into account natural factors for long-live waste (radionuclides) isolation are necessary. That's why, it is necessary to carry out specialized research and development, design and exploratory and other works on monitoring of social-ecological condition of these sites, as well as on demographic public diseases, living in these regions.

  4. A proposed definition of the 'activity' of surface sites on lactose carriers for dry powder inhalation

    NARCIS (Netherlands)

    Grasmeijer, Floris; Frijlink, Henderik W.; de Boer, Anne

    2014-01-01

    A new definition of the activity of surface sites on lactose carriers for dry powder inhalation is proposed which relates to drug detachment during dispersion. The new definition is expected to improve the understanding of 'carrier surface site activity', which stimulates the unambiguous

  5. 78 FR 8190 - Commercial Wind Leasing and Site Assessment Activities on the Atlantic Outer Continental Shelf...

    Science.gov (United States)

    2013-02-05

    ... DEPARTMENT OF THE INTERIOR Bureau of Ocean Energy Management [Docket No. BOEM-2012-0090] Commercial Wind Leasing and Site Assessment Activities on the Atlantic Outer Continental Shelf (OCS) Offshore... Assessment (EA) for Commercial Wind Leasing and Site Assessment Activities on the OCS Offshore North Carolina...

  6. Facebook, Twitter Activities Sites, Location and Students' Interest in Learning

    Science.gov (United States)

    Igbo, J. N.; Ezenwaji, Ifeyinwa; Ajuziogu, Christiana U.

    2018-01-01

    This study was carried out to ascertain the influence of social networking sites activities (twitter and Facebook) on secondary school students' interest in learning It also considered the impact of these social networking sites activities on location of the students. Two research questions and two null hypotheses guided the study. Mean and…

  7. Nanocaged enzymes with enhanced catalytic activity and increased stability against protease digestion

    Science.gov (United States)

    Zhao, Zhao; Fu, Jinglin; Dhakal, Soma; Johnson-Buck, Alexander; Liu, Minghui; Zhang, Ting; Woodbury, Neal W.; Liu, Yan; Walter, Nils G.; Yan, Hao

    2016-01-01

    Cells routinely compartmentalize enzymes for enhanced efficiency of their metabolic pathways. Here we report a general approach to construct DNA nanocaged enzymes for enhancing catalytic activity and stability. Nanocaged enzymes are realized by self-assembly into DNA nanocages with well-controlled stoichiometry and architecture that enabled a systematic study of the impact of both encapsulation and proximal polyanionic surfaces on a set of common metabolic enzymes. Activity assays at both bulk and single-molecule levels demonstrate increased substrate turnover numbers for DNA nanocage-encapsulated enzymes. Unexpectedly, we observe a significant inverse correlation between the size of a protein and its activity enhancement. This effect is consistent with a model wherein distal polyanionic surfaces of the nanocage enhance the stability of active enzyme conformations through the action of a strongly bound hydration layer. We further show that DNA nanocages protect encapsulated enzymes against proteases, demonstrating their practical utility in functional biomaterials and biotechnology. PMID:26861509

  8. Stability of Anthocyanins from Rubus glaucus and Solanum betaceum as affected by Temperature and Water Activity

    OpenAIRE

    Clara Marcela Olaya; Maria Paola Castaño; Gloria Astrid Garzon Monroy

    2009-01-01

    The stability of sprayed-dried microencapsulated anthocyanins from Andes berry (Rubus glaucus) and Tamarillo (Solanum betaceum), as affected by storage time, water activity (Aw) and temperature was compared. The fruits were osmotically dehydrated with ethanol and the anthocyanin extract was microencapsulated with maltodextrin DE 20 by spray drying. Half life of the anthocyanins; changes in color, total phenolics, and antioxidant activity of the powders, were analyzed during storage at two dif...

  9. [Phytotoxic activity of chernozem saprophytic micromycetes: specificity, sorption and stability of phytotoxins in soil].

    Science.gov (United States)

    Svistova, I D; Shcherbakov, A P; Frolova, L O

    2003-01-01

    Micromycetes of the complex of typical chernozem saprotrophic fungi released phytotoxic metabolites into medium. The metabolites displayed their phytotoxic activities directly in soil. Evaluation of the toxicities, range of biological effects activities, and stabilities of phytotoxins in soil and the rates of their biodegradation allowed the species that can serve as indicators of chernozem microbial toxicosis to be selected, namely, Aspergillus clavatus, Fusarium solani, Talaromyces flavus, Penicillium rubrum, and P. funiculosum.

  10. The Antioxidant Activity and Oxidative Stability of Cold-Pressed Oils

    OpenAIRE

    Prescha, Anna; Grajzer, Magdalena; Dedyk, Martyna; Grajeta, Halina

    2014-01-01

    In our study, we characterized the antioxidant activity and oxidative stability of cold-pressed macadamia, avocado, sesame, safflower, pumpkin, rose hip, Linola, flaxseed, walnut, hempseed, poppy, and milk thistle oils. The radical scavenging activity of the non-fractionated fresh oil, as well as the lipophilic and hydrophilic fractions of the oil was determined using a 1,1-diphenyl-2-picrylhydrazyl (DPPH) assay. The fatty acid composition of the fresh and stored oils was analyzed by gas chro...

  11. Prediction of Active Site and Distal Residues in E. coli DNA Polymerase III alpha Polymerase Activity.

    Science.gov (United States)

    Parasuram, Ramya; Coulther, Timothy A; Hollander, Judith M; Keston-Smith, Elise; Ondrechen, Mary Jo; Beuning, Penny J

    2018-02-20

    The process of DNA replication is carried out with high efficiency and accuracy by DNA polymerases. The replicative polymerase in E. coli is DNA Pol III, which is a complex of 10 different subunits that coordinates simultaneous replication on the leading and lagging strands. The 1160-residue Pol III alpha subunit is responsible for the polymerase activity and copies DNA accurately, making one error per 10 5 nucleotide incorporations. The goal of this research is to determine the residues that contribute to the activity of the polymerase subunit. Homology modeling and the computational methods of THEMATICS and POOL were used to predict functionally important amino acid residues through their computed chemical properties. Site-directed mutagenesis and biochemical assays were used to validate these predictions. Primer extension, steady-state single-nucleotide incorporation kinetics, and thermal denaturation assays were performed to understand the contribution of these residues to the function of the polymerase. This work shows that the top 15 residues predicted by POOL, a set that includes the three previously known catalytic aspartate residues, seven remote residues, plus five previously unexplored first-layer residues, are important for function. Six previously unidentified residues, R362, D405, K553, Y686, E688, and H760, are each essential to Pol III activity; three additional residues, Y340, R390, and K758, play important roles in activity.

  12. MEASUREMENT OF THE RESISTIVE WALL MODE STABILITY IN A ROTATING PLASMA USING ACTIVE MHD SPECTROSCOPY

    International Nuclear Information System (INIS)

    CHU, M.S; JACKSON, G.L; LA HAYE, R.J; SCOVILLE, J.T; STRAIT, E.J

    2003-01-01

    The stability of the resistive-wall mode (RWM) in DIII-D plasmas above the conventional pressure limit, where toroidal plasma rotation in the order of a few percent of the Alfven velocity is sufficient to stabilize the n=1 RWM, has been probed using the technique of active MHD spectroscopy at frequencies of a few Hertz. The measured frequency spectrum of the plasma response to externally applied rotating resonant magnetic fields is well described by a single mode approach and provides an absolute measurement of the damping rate and the natural mode rotation frequency of the stable RWM

  13. Stabilization of Parametric Roll Resonance with Active U-Tanks via Lyapunov Control Design

    DEFF Research Database (Denmark)

    Holden, Christian; Galeazzi, Roberto; Fossen, Thor Inge

    2009-01-01

    Parametric ship roll resonance is a phenomenon where a ship can rapidly develop high roll motion while sailing in longitudinal waves. This effect can be described mathematically by periodic changes of the parameters of the equations of motion, which lead to a bifurcation. In this paper, the control...... design of an active u-tank stabilizer is carried out using Lyapunov theory. A nonlinear backstepping controller is developed to provide global exponential stability of roll. An extension of commonly used u-tank models is presented to account for large roll angles, and the control design is tested via...... simulation on a high-fidelity model of a vessel under parametric roll resonance....

  14. Active stabilization of a Michelson interferometer at an arbitrary phase with subnanometer resolution.

    Science.gov (United States)

    Grassani, Davide; Galli, Matteo; Bajoni, Daniele

    2014-04-15

    We report on the active stabilization of a Michelson interferometer at an arbitrary phase angle with a precision better than 1° at λ=632.8  nm, which corresponds to a precision in the optical path difference between the two arms of less than 1 nm. The stabilization method is ditherless, and the error signal is computed from the spatial shift of the interference pattern of a reference laser, measured in real-time with a CCD array detector. We discuss the usefulness of this method for nanopositioning, optical interferometry, and quantum optical experiments.

  15. Effect of active-site mutation at Asn67 on the proton transfer mechanism of human carbonic anhydrase II.

    Science.gov (United States)

    Maupin, C Mark; Zheng, Jiayin; Tu, Chingkuang; McKenna, Robert; Silverman, David N; Voth, Gregory A

    2009-08-25

    The rate-limiting proton transfer (PT) event in the site-specific mutant N67L of human carbonic anhydrase II (HCA II) has been examined by kinetic, X-ray, and simulation approaches. The X-ray crystallography studies, which were previously reported, and molecular dynamics (MD) simulations indicate that the proton shuttling residue, His64, predominantly resides in the outward orientation with a significant disruption of the ordered water in the active site for the dehydration pathway. While disorder is seen in the active-site water, water cluster analysis indicates that the N67L mutant may form water clusters similar to those seen in the wild-type (WT). For the hydration pathway of the enzyme, the active site water cluster analysis reveals an inability of the N67L mutant to stabilize water clusters when His64 is in the inward orientation, thereby favoring PT when His64 is in the outward orientation. The preference of the N67L mutant to carry out the PT when His64 is in the outward orientation for both the hydration and dehydration pathway is reasoned to be the main cause of the observed reduction in the overall rate. To probe the mechanism of PT, solvent H/D kinetic isotope effects (KIEs) were experimentally studied with catalysis measured by the exchange of (18)O between CO(2) and water. The values obtained from the KIEs were determined as a function of the deuterium content of solvent, using the proton inventory method. No differences were detected in the overarching mechanism of PT between WT and N67L HCA II, despite changes in the active-site water structure and/or the orientation of His64.

  16. Iron impurities as the active sites for peroxidase-like catalytic reaction on graphene and its derivatives.

    Science.gov (United States)

    Dong, Ying; Li, Jing; Shi, Lei; Guo, Zhiguang

    2015-07-22

    We established four kinds of good dispersing systems of graphene and its derivatives with different structural characteristics to estimate their peroxidase-like activity. Besides graphene oxide (GO), it is demonstrated that defect-free graphene, low-oxygen graphene, and iron(III)-doped graphene oxide (GO-Fe) are all capable of H2O2 activation to oxidize peroxidase substrates. As for defect-free graphene, the dispersibility in reaction medium exerts great impact on its catalytic activity and our further judgements concerning the nature of active sites. Improved stability and further exfoliation of defect-free graphene in reaction medium are beneficial to the access of reactants to active sites on the basal planes and enhance its peroxidase-like activity, which is superior to that of low-oxygen graphene and much higher than that of GO. In addition, their peroxidase-like activity can be greatly inhibited by the addition of iron chelators. Interestingly, the introduction of trace ferric ions into GO does not lead to an apparent change except for remarkable increase of its peroxidase-like activity. Therefore, we propose that the observed iron impurities rather than the doped nonmetallic heteroatoms play an important role in the peroxidase-like activity of graphene and its derivatives. In this light, saturated iron(III) was immobilized onto the oxygen-donor coordination of GO to immensely promote its activity. The peroxidase-like activity of the prepared GO-Fe was systematically evaluated by using 3,3',5,5'-tetramethylbenzidine and pyrogallol as peroxidase substrates and was compared to that of horseradish peroxidase and hemin. As a result, GO-Fe shows excellent peroxidase-like catalytic activity, which is comparable to that of hemin. Furthermore, GO-Fe was used for the quantitative detection of H2O2 and glucose.

  17. Assessment of activation products in the Savannah River Site environment

    International Nuclear Information System (INIS)

    Carlton, W.H.; Denham, M.

    1996-07-01

    This document assesses the impact of radioactive activation products released from SRS facilities since the first reactor became operational late in 1953. The isotopes reported here are those whose release resulted in the highest dose to people living near SRS: 32 P, 51 Cr, 60 C, and 65 Zn. Release pathways, emission control features, and annual releases to the aqueous and atmospheric environments are discussed. No single incident has resulted in a major acute release of activation products to the environment. The releases were the result of normal operations of the reactors and separations facilities. Releases declined over the years as better controls were established and production was reduced. The overall radiological impact of SRS activation product atmospheric releases from 1954 through 1994 on the offsite maximally exposed individual can be characterized by a total dose of 0.76 mrem. During the same period, such an individual received a total dose of 14,400 mrem from non-SRS sources of ionizing radiation present in the environment. SRS activation product aqueous releases between 1954 and 1994 resulted in a total dose of 54 mrem to the offsite maximally exposed individual. The impact of SRS activation product releases on offsite populations also has been evaluated

  18. Effect of Alkaline Activator to Fly Ash Ratio for Geopolymer Stabilized Soil

    Directory of Open Access Journals (Sweden)

    Abdullah Muhammad Sofian

    2017-01-01

    Full Text Available Geopolymer technology have been developed and explored especially in the construction material field. However, lack of research related to geopolymer stabilized soil. In this research, the utilization of geopolymer has been investigated to stabilize the soil including the factors that affecting the geopolymerization process. Unconfined compressive test (UCT used as indicator to the strength development and hence evaluating the performance of geopolymer stabilized soil. This paper focusing on the effect of fly ash/alkaline activator ratio, Na2SiO3/NaOH ratio and curing time on geopolymer stabilized soil. A various mix design at different fly ash/alkaline activator ratio, Na2SiO3/NaOH ratio were prepared and cured for 7 and 28 days. Molarity and the percentage of geopolymer to soil were fixed at 10 molar and 8 percent respectively. Then, the UCT tests were carried out on 38mm diameter x 76mm height specimens. The highest strength obtained at the fly ash/alkaline activator ratio 2.5 and Na2SiO3/NaOH ratio 2.0 at 28 days curing time.

  19. Apoferritin Nanoparticle: A Novel and Biocompatible Carrier for Enzyme Immobilization with Enhanced Activity and Stability

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Youyu; Tang, Zhiwen; Wang, Jun; Wu, Hong J.; Lin, Chiann Tso; Lin, Yuehe

    2011-11-01

    Apoferritin is a nanostructured material with a uniform size and spherical structure, and it has excellent bio-compatibility. In this work, we report the use of apoferritin as a novel and biocompatible carrier for stabilizing enzymes and their activities. We used glucose oxidase (GOx) as a model enzyme. GOx was immobilized on the surface of the apoferritin through a green synthetic approach taking advantage of bioaffinity binding between streptavidin and biotin. As a result, a glucose oxidase-biotin/streptavidin/biotin-apoferritin conjugate (Apo-GOx) was prepared using streptavidin as a bridge. The synthesized Apo-GOx was characterized with transmission electron microscopy, ultraviolet, and fluorescence spectroscopy. The activity and stability of GOx on the surface of the apoferritin were studied in different environments, such as temperature, chemicals, and pH, in comparison with the biotinylated GOx (B-GOx). The results showed that the activity of GOx on the apoferritin surface was significantly enhanced. The thermal and chemical stability of the GOx on the apoferritin was also greatly improved compared to free B-GOx in a solution. It was found that the activity of the GOx on the apoferritin only lost 30% in comparison to a 70% loss of free B-GOx after a 2 h incubation at 50oC. There was almost no decrease in activity for the GOx on the apoferritin as compared to an 80% activity decrease for free B-GOx after 30 min incubation in a 5 M urea solution. Glucose detection was used as a model application for the enzyme immobilization method developed in this work. The GOx immobilized apoferritin nanoparticles exhibited high sensitivity for glucose detection with a detection limit of 3 nM glucose. This work offers a novel approach for immobilizing enzymes with enhanced stability and activity, and this method may find a number of applications, such as in enzyme catalysis, DNA assays and immunoassays.

  20. HDAC Inhibitors without an Active Site Zn2+-Binding Group

    DEFF Research Database (Denmark)

    Vickers, Chris J.; Olsen, Christian Adam; Leman, Luke J.

    2012-01-01

    -target interactions with other metalloenzymes. As a step toward mitigating this issue, here, we describe the design, synthesis, and structure−activity characterizations of cyclic α3β-tetrapeptide HDAC inhibitors that lack the presumed indispensable Zn2+-binding group. The lead compounds (e.g., 15 and 26) display good...... potency against class 1 HDACs and are active in tissue culture against various human cancer cell lines. Importantly, enzymological analysis of 26 indicates that the cyclic α3β-tetrapeptide is a fast-on/ off competitive inhibitor of HDACs 1−3 with Ki values of 49, 33, and 37 nM, respectively. Our proof...

  1. Temporal stability and drivers of change in cardiac autonomic nervous system activity.

    Science.gov (United States)

    Hu, Mandy X; Lamers, Femke; Penninx, Brenda W J H; de Geus, Eco J C

    2017-12-01

    This study determined temporal stability of ambulatory measured cardiac autonomic activity for different time periods and investigated potential drivers of changes in this activity. Data was drawn from baseline (n=2379), 2-year (n=2245), and 6-year (n=1876) follow-up from the Netherlands Study of Depression and Anxiety. Cardiac autonomic activity was measured with heart rate (HR), respiratory sinus arrhythmia (RSA) and pre-ejection period (PEP). Autonomic temporal stability was determined across 2, 4, and 6year intervals. We subsequently examined the association between sociodemographics, lifestyle, mental health, cardiometabolic health, and the use of antidepressant and cardiac medication with change in cardiac autonomic activity. Over 2years, stability was good for HR (ICC=0.703), excellent for RSA (ICC=0.792) and moderate for PEP (ICC=0.576). Stability decreased for a 4- (HR ICC=0.688, RSA ICC=0.652 and PEP ICC=0.387) and 6-year interval (HR ICC=0.633, RSA ICC=0.654 and PEP ICC=0.355). The most important determinants for increase in HR were (increase in) smoking, increase in body mass index (BMI) and (starting) the use of antidepressants. Beta-blocking/antiarrhythmic drug use led to a decrease in HR. Decrease in RSA was associated with age, smoking and (starting) antidepressant use. Decrease in PEP was associated with age and (increase in) BMI. Cardiac autonomic measures were rather stable over 2years, but stability decreased with increasing time span. Determinants contributing to cardiac autonomic deterioration were older age, (increase in) smoking and BMI, and (starting) the use of antidepressants. (Starting) the use of cardiac medication improved autonomic function. Copyright © 2017 Elsevier B.V. All rights reserved.

  2. The Stability, Sustained Release and Cellular Antioxidant Activity of Curcumin Nanoliposomes

    Directory of Open Access Journals (Sweden)

    Xing Chen

    2015-08-01

    Full Text Available Curcumin is a multifunctional and natural agent considered to be pharmacologically safe. However, its application in the food and medical industry is greatly limited by its poor water solubility, physicochemical instability and inadequate bioavailability. Nanoliposome encapsulation could significantly enhance the solubility and stability of curcumin. Curcumin nanoliposomes exhibited good physicochemical properties (entrapment efficiency = 57.1, particle size = 68.1 nm, polydispersity index = 0.246, and zeta potential = −3.16 mV. Compared with free curcumin, curcumin nanoliposomes exhibited good stability against alkaline pH and metal ions as well as good storage stability at 4 °C. Curcumin nanoliposomes also showed good sustained release properties. Compared with free curcumin, curcumin nanoliposomes presented an equal cellular antioxidant activity, which is mainly attributed to its lower cellular uptake as detected by fluorescence microscopy and flow cytometry. This study provide theoretical and practical guides for the further application of curcumin nanoliposomes.

  3. Towards passive and active laser stabilization using cavity-enhanced atomic interaction

    DEFF Research Database (Denmark)

    Schäffer, Stefan Alaric; Christensen, Bjarke Takashi Røjle; Rathmann, Stefan Mossor

    2017-01-01

    Ultra stable frequency references such as the ones used in optical atomic clocks and for quantum metrology may be obtained by stabilizing a laser to an optical cavity that is stable over time. State-of-the-art frequency references are constructed in this way, but their stabilities are currently...... experimental efforts derived from these proposals, to use cavity-enhanced interaction with atomic 88Sr samples as a frequency reference for laser stabilization. Such systems can be realized using both passive and active approaches where either the atomic phase response is used as an error signal, or the narrow...... atomic transition itself is used as a source for a spectrally pure laser. Both approaches shows the promise of being able to compete with the current state of the art in stable lasers and have similar limitations on their ultimately achievable linewidths [1, 2]....

  4. Active feedback stabilization of the flute instability in a mirror machine using field-aligned coils

    International Nuclear Information System (INIS)

    Lifshitz, A.; Be'ery, I.; Fisher, A.; Ron, A.; Fruchtman, A.

    2012-01-01

    A plasma confined in linear mirror machines is unstable even at low β, mainly because of the flute instability. One possible way to stabilize the plasma is to use active feedback to correct the plasma shape in real time. The theoretically investigated apparatus consists of feedback coils aligned with the magnetic field, immersed in a cold plasma around the hot core. When the current through the feedback coils changes, the plasma moves to conserve the magnetic flux via compressional Alfvén waves. An analytical model is used to find a robust feedback algorithm with zero residual currents. It is shown that due to the plasma's rotation, maximal stability is obtained with a large phase angle between the perturbations' modes and the feedback integral-like term. Finally, a two-dimensional MHD simulation implementing the above algorithm in fact shows stabilization of the plasma with zero residual currents. (paper)

  5. Active Frequency Stabilization Method for Sensitive Applications Operating in Variable Temperature Environments

    Directory of Open Access Journals (Sweden)

    DONE, A.

    2018-02-01

    Full Text Available This article proposes a cost efficient and easy to implement frequency stabilization method orientated toward communication systems operating in an extensive temperature range, as the automotive or the aerospace applications. The proposed solution uses off-the-shelf components and it is optimized for very low power consumption. The novelty of this article is represented by the introduction of the barium strontium titanate capacitor for quartz crystal oscillator active frequency stabilization. After the design was completed, the performances were evaluated and compared to the ones of the uncompensated oscillator. Experimental results confirmed the suitability of the proposed design, achieving 35 times better frequency stability within variable temperature conditions, whereas the power consumption is maintained below 6mW.

  6. Understanding the role of aluminum-based activators in single site iron catalysts for ethylene oligomerization.

    OpenAIRE

    Boudene , Zoubeyr; Boudier , Adrien; Breuil , Pierre-Alain; Olivier-Bourbigou , Hélène; Raybaud , Pascal; Toulhoat , Hervé; De Bruin , Theodorus

    2014-01-01

    International audience; In a combined experimental and theoretical study, the activation process of a single site ethylene oligomerization catalyst with aluminum-based activators has been studied. The results put forward a plausible deactivation reaction path of the catalyst for trimethylaluminum, while for methylaluminoxane and a novel phenoxyaluminum-based activator, the experimental catalyst's activity correlates with the energy barrier for the ethylene insertion.

  7. Site directed mutagenesis of amino acid residues at the active site of mouse aldehyde oxidase AOX1.

    Directory of Open Access Journals (Sweden)

    Silvia Schumann

    Full Text Available Mouse aldehyde oxidase (mAOX1 forms a homodimer and belongs to the xanthine oxidase family of molybdoenzymes which are characterized by an essential equatorial sulfur ligand coordinated to the molybdenum atom. In general, mammalian AOs are characterized by broad substrate specificity and an yet obscure physiological function. To define the physiological substrates and the enzymatic characteristics of mAOX1, we established a system for the heterologous expression of the enzyme in Escherichia coli. The recombinant protein showed spectral features and a range of substrate specificity similar to the native protein purified from mouse liver. The EPR data of recombinant mAOX1 were similar to those of AO from rabbit liver, but differed from the homologous xanthine oxidoreductase enzymes. Site-directed mutagenesis of amino acids Val806, Met884 and Glu1265 at the active site resulted in a drastic decrease in the oxidation of aldehydes with no increase in the oxidation of purine substrates. The double mutant V806E/M884R and the single mutant E1265Q were catalytically inactive enzymes regardless of the aldehyde or purine substrates tested. Our results show that only Glu1265 is essential for the catalytic activity by initiating the base-catalyzed mechanism of substrate oxidation. In addition, it is concluded that the substrate specificity of molybdo-flavoenzymes is more complex and not only defined by the three characterized amino acids in the active site.

  8. Location and activity specific site-management for military locations

    NARCIS (Netherlands)

    Maring, L.; Hulst, M. van; Meuken, D.

    2009-01-01

    pace is limited in the Netherlands and military activities, that may cause nuisance or environmental hazards, should therefore be considered and evaluated during the use of military locations. The last few years TNO and Deltares have worked on a research program on environmental effects due to

  9. The landscape degradation in the mining sites with suspended activity

    Directory of Open Access Journals (Sweden)

    Anca IONCE

    2009-08-01

    Full Text Available The extracting industry, through its extraction activities, of shipping the ores, of breaking the ores, of preparing the practical substances, of stowing the useless rock, of transporting the practical substances, etc. might modify the area’s relief and the quality of ground, of thesurface waters and of the air. Suceava County has an old tradition of mining, where the results of this activity are visible, especially the visual point of view, and where not taking certain measures of ecological remediation will emphasize the disappointing image of the landscape within the areas of mining activity performing.The predominant mountainous landscape, in which mining activities have been held, is being affected also by the abandoned industrial and administrative buildings, in an advanced degradation state.The hydrographic system, very rich in mining areas, has its water quality affected by the acid rock drainage- phenomenon which appeared in many mining waste deposits.

  10. Hydrogen bonding effect between active site and protein environment on catalysis performance in H2-producing [NiFe] hydrogenases.

    Science.gov (United States)

    Qiu, Siyao; Azofra, Luis Miguel; MacFarlane, Douglas R; Sun, Chenghua

    2018-02-28

    The interaction between the active site and the surrounding protein environment plays a fundamental role in the hydrogen evolution reaction (HER) in [NiFe] hydrogenases. Our density functional theory (DFT) findings demonstrate that the reaction Gibbs free energy required for the rate determining step decreases by 7.1 kcal mol -1 when the surrounding protein environment is taken into account, which is chiefly due to free energy decreases for the two H + /e - addition steps (the so-called Ni-SIa to I1, and Ni-C to Ni-R), being the largest thermodynamic impediments of the whole reaction. The variety of hydrogen bonds (H-bonds) between the amino acids and the active site is hypothesised to be the main reason for such stability: H-bonds not only work as electrostatic attractive forces that influence the charge redistribution, but more importantly, they act as an electron 'pull' taking electrons from the active site towards the amino acids. Moreover, the electron 'pull' effect through H-bonds via the S - in cysteine residues shows a larger influence on the energy profile than that via the CN - ligands on Fe.

  11. Impact of Power Ultrasound on Antihypertensive Activity, Functional Properties, and Thermal Stability of Rapeseed Protein Hydrolysates

    Directory of Open Access Journals (Sweden)

    Asif Wali

    2017-01-01

    Full Text Available The effects of power ultrasound pretreatments on the degree of hydrolysis (DH, angiotensin-I-converting enzyme (ACE inhibitory activity, amino acid composition, surface hydrophobicity, protein solubility, and thermal stability of ACE inhibition of rapeseed protein hydrolysates were evaluated. Ultrasonic pretreatments before enzymolysis in terms of power and exposure time increased the DH and ACE inhibitory activities over the control (without sonication. In this study, maximum DH 22.07% and ACE inhibitory activity 72.13% were achieved at 600 W and 12 min pretreatment. Compared to the hydrolysates obtained without sonication, the amino acid profile of ultrasound pretreated hydrolysates showed significant changes particularly in the proline content and hydrophobic amino acids with an increased rate of 2.47% and 6.31%, respectively. Ultrasound pretreatment (600 watts, 12 min improved functional properties of protein hydrolysates over control by enhancing surface hydrophobicity and solubility index with an increased rate of 130.76% and 34.22%. Moreover, the stability test showed that the ACE inhibitory activity remains stable against heat treatments. However, extensive heat, prolonged heating time, and alkaline conditions were not in the favor of stability test, while under mild heat and acidic conditions their ACE inhibitory activities were not significantly different from unheated samples.

  12. Semisynthetic modifications of hemiaminal function at ornithine unit of mulundocandin, towards chemical stability and antifungal activity.

    Science.gov (United States)

    Lal, Bansi; Gund, Vitthal Genbhau; Gangopadhyay, Ashok Kumar; Nadkarni, S R; Dikshit, Vidula; Chatterjee, D K; Shirvaikar, R

    2003-11-17

    Mulundocandin (1), is an echinocandin class of lipopeptide. It has wide spectrum of antifungal activity against Candida and Aspergillus species. Semisynthetic modification at Ornithine-5-hydroxyl (hemiaminal function) of 1 was carried out to improve solution stability and hence in vivo activity. Synthesis of ether (C-OR), thioether (C-SR) and C-N linkage at hemiaminal function have been described. All synthetic analogues were evaluated for their stability in aqueous solution and found to be more stable than mulundocandin. Antifungal activity of Orn-5 analogues was evaluated both in vitro against Candida albicans and Aspergillus fumigatus by agar well method and in vivo (oral and intraperitoneal) in C. albicans infected Swiss mice. Results of in vivo assays of analogues 2-9 by the oral route suggests that the introduction of either oxygen nucleophiles (-OR) or sulphur nucleophiles (-SR), at either Orn-5 or at both Orn-5 and HTyr-4 positions, results in retaining the activity of the parent compound with improved aqueous stability in most cases. Compound 9 has shown improved antifungal activity in comparison to mulundocandin by oral application in Swiss mice.

  13. The Antioxidant Activity and Oxidative Stability of Cold-Pressed Oils.

    Science.gov (United States)

    Prescha, Anna; Grajzer, Magdalena; Dedyk, Martyna; Grajeta, Halina

    2014-01-01

    In our study, we characterized the antioxidant activity and oxidative stability of cold-pressed macadamia, avocado, sesame, safflower, pumpkin, rose hip, Linola, flaxseed, walnut, hempseed, poppy, and milk thistle oils. The radical scavenging activity of the non-fractionated fresh oil, as well as the lipophilic and hydrophilic fractions of the oil was determined using a 1,1-diphenyl-2-picrylhydrazyl (DPPH) assay. The fatty acid composition of the fresh and stored oils was analyzed by gas chromatography. The acid value, peroxide value, p -anisidine value and conjugated diene and triene contents in the fresh oils, as well as in those stored throughout the whole period of their shelf life, were measured by CEN ISO methods. The antioxidant activity of the oils expressed as Trolox equivalent antioxidant capacity (TEAC), ranged from 0.17 to 2.32 mM. The lipophilic fractions of the oils were characterized by much higher antioxidant activity than the hydrophilic ones. There were no significant changes in fatty acid composition and only slight changes in the oxidative stability parameters of the oils during their shelf life. Through the assessment of the relationship between antiradical activity and the oxidative stability of oils, it is proposed that a DPPH assay predicts the formation of oxidation products in cold-pressed oils-however, the correlations differ in fractionated and nonfractionated oils.

  14. Quantifying the density and utilization of active sites in non-precious metal oxygen electroreduction catalysts

    Science.gov (United States)

    Sahraie, Nastaran Ranjbar; Kramm, Ulrike I.; Steinberg, Julian; Zhang, Yuanjian; Thomas, Arne; Reier, Tobias; Paraknowitsch, Jens-Peter; Strasser, Peter

    2015-01-01

    Carbon materials doped with transition metal and nitrogen are highly active, non-precious metal catalysts for the electrochemical conversion of molecular oxygen in fuel cells, metal air batteries, and electrolytic processes. However, accurate measurement of their intrinsic turn-over frequency and active-site density based on metal centres in bulk and surface has remained difficult to date, which has hampered a more rational catalyst design. Here we report a successful quantification of bulk and surface-based active-site density and associated turn-over frequency values of mono- and bimetallic Fe/N-doped carbons using a combination of chemisorption, desorption and 57Fe Mössbauer spectroscopy techniques. Our general approach yields an experimental descriptor for the intrinsic activity and the active-site utilization, aiding in the catalyst development process and enabling a previously unachieved level of understanding of reactivity trends owing to a deconvolution of site density and intrinsic activity. PMID:26486465

  15. Remedial Action Plan and site design for stabilization of the inactive uranium mill tailings site at Durango, Colorado: Attachment 5, Dewatering report

    International Nuclear Information System (INIS)

    1991-12-01

    This report provides an update on dewatering activities at the Durango disposal embankment and presents recommendations for the work required to complete the closure of the cell in 1990 (Section 2). In October 1989, test pit investigations were performed and a toe trench was excavated at the eastern slope of the disposal embankment. A description and results of the test pit investigations along with the implications . of the results relative to the over . all dewatering effort are discussed in Sections 3 through 5. Installation and performance of the 17-well dewatering system were previously described in' the ''StatusReport on Dewatering of Disposal Embankment'' issued in September, 1989. Additional studies are still on-going and are described in Section 6. Laboratory analysis continues on samples taken from the test pits. TAC's characterization of the hydrogeological conditions at the Durango site is also proceeding. Results of these studies will be presented in subsequent reports. Appendices A and B present construction details of the well point system, toe trench and holding pond. Appendix C summarizes the performance-of the 17 pumping wells prior to winter shutdown and provides information on pumping rates, drawdowns, and disposition of the wells. Appendix D outlines the chronology of the dewatering effort to date

  16. Encroachment of Human Activity on Sea Turtle Nesting Sites

    Science.gov (United States)

    Ziskin, D.; Aubrecht, C.; Elvidge, C.; Tuttle, B.; Baugh, K.; Ghosh, T.

    2008-12-01

    The encroachment of anthropogenic lighting on sea turtle nesting sites poses a serious threat to the survival of these animals [Nicholas, 2001]. This danger is quantified by combining two established data sets. The first is the Nighttime Lights data produced by the NOAA National Geophysical Data Center [Elvidge et al., 1997]. The second is the Marine Turtle Database produced by the World Conservation Monitoring Centre (WCMC). The technique used to quantify the threat of encroachment is an adaptation of the method described in Aubrecht et al. [2008], which analyzes the stress on coral reef systems by proximity to nighttime lights near the shore. Nighttime lights near beaches have both a direct impact on turtle reproductive success since they disorient hatchlings when they mistake land-based lights for the sky-lit surf [Lorne and Salmon, 2007] and the lights are also a proxy for other anthropogenic threats. The identification of turtle nesting sites with high rates of encroachment will hopefully steer conservation efforts to mitigate their effects [Witherington, 1999]. Aubrecht, C, CD Elvidge, T Longcore, C Rich, J Safran, A Strong, M Eakin, KE Baugh, BT Tuttle, AT Howard, EH Erwin, 2008, A global inventory of coral reef stressors based on satellite observed nighttime lights, Geocarto International, London, England: Taylor and Francis. In press. Elvidge, CD, KE Baugh, EA Kihn, HW Kroehl, ER Davis, 1997, Mapping City Lights with Nighttime Data from the DMSP Operational Linescan System, Photogrammatic Engineering and Remote Sensing, 63:6, pp. 727-734. Lorne, JK, M Salmon, 2007, Effects of exposure to artificial lighting on orientation of hatchling sea turtles on the beach and in the ocean, Endangered Species Research, Vol. 3: 23-30. Nicholas, M, 2001, Light Pollution and Marine Turtle Hatchlings: The Straw that Breaks the Camel's Back?, George Wright Forum, 18:4, p77-82. Witherington, BE, 1999, Reducing Threats To Nesting Habitat, Research and Management Techniques for

  17. Rac1 GTPase activates the WAVE regulatory complex through two distinct binding sites

    Science.gov (United States)

    Brautigam, Chad A; Xing, Wenmin; Yang, Sheng; Henry, Lisa; Doolittle, Lynda K; Walz, Thomas

    2017-01-01

    The Rho GTPase Rac1 activates the WAVE regulatory complex (WRC) to drive Arp2/3 complex-mediated actin polymerization, which underpins diverse cellular processes. Here we report the structure of a WRC-Rac1 complex determined by cryo-electron microscopy. Surprisingly, Rac1 is not located at the binding site on the Sra1 subunit of the WRC previously identified by mutagenesis and biochemical data. Rather, it binds to a distinct, conserved site on the opposite end of Sra1. Biophysical and biochemical data on WRC mutants confirm that Rac1 binds to both sites, with the newly identified site having higher affinity and both sites required for WRC activation. Our data reveal that the WRC is activated by simultaneous engagement of two Rac1 molecules, suggesting a mechanism by which cells may sense the density of active Rac1 at membranes to precisely control actin assembly. PMID:28949297

  18. Remedial action plan and site design for stabilization of the inactive uranium mill tailings sites at Rifle, Colorado. Volume 2, Appendices D and E: Final report

    Energy Technology Data Exchange (ETDEWEB)

    1992-02-01

    This appendix assesses the present conditions and data gathered about the two inactive uranium mill tailings sites near Rifle, Colorado, and the designated disposal site six miles north of Rifle in the area of Estes Gulch. It consolidates available engineering, radiological, geotechnical, hydrological, meteorological, and other information pertinent to the design of the Remedial Action Plan (RAP). The data characterize conditions at the mill, tailings, and disposal site so that the Remedial Action Contractor (RAC) may complete final designs for the remedial actions.

  19. Report on the use of stability parameters and mesoscale modelling in short-term prediction[Wind speed at wind farm sites

    Energy Technology Data Exchange (ETDEWEB)

    Badger, J.; Giebel, G.; Guo Larsen, X.; Skov Nielsen, T.; Aalborg Nielsen, H.; Madsen, Henrik; Toefting, J.

    2007-06-15

    In this report investigations using atmospheric stability measures to improve wind speed predictions at wind farm sites are described. Various stability measures have been calculated based on numerical weather prediction model output. Their ability to improve the wind speed predictions is assessed at three locations. One of the locations is in complex terrain. Mesoscale modelling has been carried out using KAMM at this location. The characteristics of the measured winds are captured well by the mesoscale modelling. It can be seen that the atmospheric stability plays an important role in determining how the flow is influence by the terrain. A prediction system employing a look-up table approach based on wind class simulations is presented. The mesoscale modelling results produced by KAMM were validated using an alternative mesoscale model called WRF. A good agreement in the results of KAMM and WRF was found. It is shown that including a stability parameter in physical and/or statistical modelling can improve the wind speed predictions at a wind farm site. A concept for the inclusion of a stability measure in the WPPT prediction system is presented, and the testing of the concept is outlined. (au)

  20. Lipolytic activity from bacteria prospected in polluted portuary sites

    Directory of Open Access Journals (Sweden)

    Kaori Levy Fonseca

    2014-06-01

    This study demonstrates that these TBT resistant isolates have, at the same time, the capacity to produce enzymes with a large biotechnological potential but, nevertheless, their relationship is not well understood, representing a novel approach. It is expected for these organisms to produce highly biotechnological relevant biocatalysts, due to their severe adaptations (Suehiro et al., 2007. The fully characterization of these lipases, mostly for F3 with elevated lipolytic activity exhibited, presents also a future challenge.

  1. Time Multiplexed Active Neural Probe with 1356 Parallel Recording Sites

    Directory of Open Access Journals (Sweden)

    Bogdan C. Raducanu

    2017-10-01

    Full Text Available We present a high electrode density and high channel count CMOS (complementary metal-oxide-semiconductor active neural probe containing 1344 neuron sized recording pixels (20 µm × 20 µm and 12 reference pixels (20 µm × 80 µm, densely packed on a 50 µm thick, 100 µm wide, and 8 mm long shank. The active electrodes or pixels consist of dedicated in-situ circuits for signal source amplification, which are directly located under each electrode. The probe supports the simultaneous recording of all 1356 electrodes with sufficient signal to noise ratio for typical neuroscience applications. For enhanced performance, further noise reduction can be achieved while using half of the electrodes (678. Both of these numbers considerably surpass the state-of-the art active neural probes in both electrode count and number of recording channels. The measured input referred noise in the action potential band is 12.4 µVrms, while using 678 electrodes, with just 3 µW power dissipation per pixel and 45 µW per read-out channel (including data transmission.

  2. Recent progress in volcanism studies: Site characterization activities for the Yucca Mountain site characterization project

    International Nuclear Information System (INIS)

    Crowe, B.M.; Valentine, G.; Morley, R.; Perry, F.V.

    1992-01-01

    Significant progress has been made on volcanism studies over the past calendar year. There are a number of major highlights from this work. Geochronology data have been obtained for the Lathrop Wells center using a range of isotopic, radiogenic, and age-calibrated methods. Initial work is encouraging but still insufficient to resolve the age of the center with confidence. Geologic mapping of the Sleeping Butte volcanic centers was completed and a report issued on the geology and chronology data. Twenty shallow trenches have been constructed in volcanic units of the Lathrop Wells volcanic center. Results of detailed studies of the trenches support a polycyclic eruptive history. New soil data from the trenches continue to support a late Pleistocene or Holocene age for many of the volcanic units at the center. Geochemical data (trace element and isotopic analysis) show that the volcanic units of the Lathrop Wells center cannot be related to one another by fractional crystallization of a single magma batch, supporting a polycyclic model of volcanism. Structural models using existing data are used to evaluate the probability of magmatic disruption of a potential repository. Several permissive models have been developed but none lead to significant differences in calculating the disruption ratio. Work was initiated on the eruptive and subsurface effects of magmatic activity on a repository. (author)

  3. Adaptive Neural-Sliding Mode Control of Active Suspension System for Camera Stabilization

    Directory of Open Access Journals (Sweden)

    Feng Zhao

    2015-01-01

    Full Text Available The camera always suffers from image instability on the moving vehicle due to the unintentional vibrations caused by road roughness. This paper presents a novel adaptive neural network based on sliding mode control strategy to stabilize the image captured area of the camera. The purpose is to suppress vertical displacement of sprung mass with the application of active suspension system. Since the active suspension system has nonlinear and time varying characteristics, adaptive neural network (ANN is proposed to make the controller robustness against systematic uncertainties, which release the model-based requirement of the sliding model control, and the weighting matrix is adjusted online according to Lyapunov function. The control system consists of two loops. The outer loop is a position controller designed with sliding mode strategy, while the PID controller in the inner loop is to track the desired force. The closed loop stability and asymptotic convergence performance can be guaranteed on the basis of the Lyapunov stability theory. Finally, the simulation results show that the employed controller effectively suppresses the vibration of the camera and enhances the stabilization of the entire camera, where different excitations are considered to validate the system performance.

  4. Cooperative activation of cardiac transcription through myocardin bridging of paired MEF2 sites

    Energy Technology Data Exchange (ETDEWEB)

    Anderson, Courtney M. [Univ. of California, San Francisco, CA (United States). Cardiovascular Research Inst.; Hu, Jianxin [Univ. of California, San Francisco, CA (United States). Cardiovascular Research Inst.; Thomas, Reuben [Univ. of California, San Francisco, CA (United States). Gladstone Inst.; Gainous, T. Blair [Univ. of California, San Francisco, CA (United States). Cardiovascular Research Inst.; Celona, Barbara [Univ. of California, San Francisco, CA (United States). Cardiovascular Research Inst.; Sinha, Tanvi [Univ. of California, San Francisco, CA (United States). Cardiovascular Research Inst.; Dickel, Diane E. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Genomics Division; Heidt, Analeah B. [Univ. of California, San Francisco, CA (United States). Cardiovascular Research Inst.; Xu, Shan-Mei [Univ. of California, San Francisco, CA (United States). Cardiovascular Research Inst.; Bruneau, Benoit G. [Univ. of California, San Francisco, CA (United States). Cardiovascular Research Inst.; Univ. of California, San Francisco, CA (United States). Gladstone Inst.; Pollard, Katherine S. [Univ. of California, San Francisco, CA (United States). Gladstone Inst.; Pennacchio, Len A. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Genomics Division; Black, Brian L. [Univ. of California, San Francisco, CA (United States). Cardiovascular Research Inst.; Univ. of California, San Francisco, CA (United States). Dept. of

    2017-03-28

    Enhancers frequently contain multiple binding sites for the same transcription factor. These homotypic binding sites often exhibit synergy, whereby the transcriptional output from two or more binding sites is greater than the sum of the contributions of the individual binding sites alone. Although this phenomenon is frequently observed, the mechanistic basis for homotypic binding site synergy is poorly understood. Here in this paper, we identify a bona fide cardiac-specific Prkaa2 enhancer that is synergistically activated by homotypic MEF2 binding sites. We show that two MEF2 sites in the enhancer function cooperatively due to bridging of the MEF2C-bound sites by the SAP domain-containing co-activator protein myocardin, and we show that paired sites buffer the enhancer from integration site-dependent effects on transcription in vivo. Paired MEF2 sites are prevalent in cardiac enhancers, suggesting that this might be a common mechanism underlying synergy in the control of cardiac gene expression in vivo.

  5. Active site proton delivery and the lyase activity of human CYP17A1

    Energy Technology Data Exchange (ETDEWEB)

    Khatri, Yogan; Gregory, Michael C.; Grinkova, Yelena V.; Denisov, Ilia G.; Sligar, Stephen G., E-mail: s-sligar@illinois.edu

    2014-01-03

    equivalents and protons are funneled into non-productive pathways. This is similar to previous work with other P450 catalyzed hydroxylation. However, catalysis of carbon–carbon bond scission by the T306A mutant was largely unimpeded by disruption of the CYP17A1 acid-alcohol pair. The unique response of CYP17A1 lyase activity to mutation of Thr306 is consistent with a reactive intermediate formed independently of proton delivery in the active site, and supports involvement of a nucleophilic peroxo-anion rather than the traditional Compound I in catalysis.

  6. Structural Insights into the Catalytic Active Site and Activity of Human Nit2/ω-Amidase

    Science.gov (United States)

    Chien, Chin-Hsiang; Gao, Quan-Ze; Cooper, Arthur J. L.; Lyu, Jyun-Hong; Sheu, Sheh-Yi

    2012-01-01

    Human nitrilase-like protein 2 (hNit2) is a putative tumor suppressor, recently identified as ω-amidase. hNit2/ω-amidase plays a crucial metabolic role by catalyzing the hydrolysis of α-ketoglutaramate (the α-keto analog of glutamine) and α-ketosuccinamate (the α-keto analog of asparagine), yielding α-ketoglutarate and oxaloacetate, respectively. Transamination between glutamine and α-keto-γ-methiolbutyrate closes the methionine salvage pathway. Thus, hNit2/ω-amidase links sulfur metabolism to the tricarboxylic acid cycle. To elucidate the catalytic specificity of hNit2/ω-amidase, we performed molecular dynamics simulations on the wild type enzyme and its mutants to investigate enzyme-substrate interactions. Binding free energies were computed to characterize factors contributing to the substrate specificity. The predictions resulting from these computations were verified by kinetic analyses and mutational studies. The activity of hNit2/ω-amidase was determined with α-ketoglutaramate and succinamate as substrates. We constructed three catalytic triad mutants (E43A, K112A, and C153A) and a mutant with a loop 116–128 deletion to validate the role of key residues and the 116–128 loop region in substrate binding and turnover. The molecular dynamics simulations successfully verified the experimental trends in the binding specificity of hNit2/ω-amidase toward various substrates. Our findings have revealed novel structural insights into the binding of substrates to hNit2/ω-amidase. A catalytic triad and the loop residues 116–128 of hNit2 play an essential role in supporting the stability of the enzyme-substrate complex, resulting in the generation of the catalytic products. These observations are predicted to be of benefit in the design of new inhibitors or activators for research involving cancer and hyperammonemic diseases. PMID:22674578

  7. STABILIZATION OF ACTIVE SLUDGE AFTER WASTEWATER TREATMENT CONTAMINATED BY PETROLEUM PRODUCTS

    Directory of Open Access Journals (Sweden)

    Olena Semenova

    2016-06-01

    Full Text Available Purpose: Biochemical purification of wastewater containing refined petroleum products takes place due to the oxidation of pollutants by active sludge organisms. As a result of this process the intense consumption of pollutants by active sludge and its growth occurs. Therefore, the possibility to use active sludge containing refined petroleum products after wastewater treatment requires its stabilization. Methods: In this work the oxidation by a 30% hydrogen peroxide solution was studied for its use as a stabilizer. Chemical oxidizers, including hydrogen peroxide destroy organic polymers retaining free water thus promoting water release from the structure of sludge particles. On the other hand remains of fine structured oxidized biopolymers can lead to filter clogging, that is, reduce moisture exchange of sludge. Results: The experiment was carried out to find out the correlation between the doses of hydrogen peroxide and the resistivity value of sludge filtration. Discussion: Stabilized active sludge can be used as a fuel for boiler rooms, which in its turn will reduce natural gas consumption for the enterprise needs.

  8. Alkyl caffeates improve the antioxidant activity, antitumor property and oxidation stability of edible oil.

    Directory of Open Access Journals (Sweden)

    Jun Wang

    Full Text Available Caffeic acid (CA is distributed widely in nature and possesses strong antioxidant activity. However, CA has lower solubility in non-polar media, which limits its application in fat-soluble food. To increase the lipophilicity of natural antioxidant CA, a series of alkyl caffeates were synthesized and their antioxidant and antitumor activities were investigated. The antioxidant parameters, including the induction period, acid value and unsaturated fatty acid content, of the alkyl caffeates in edible oil were firstly investigated. The results indicated that alkyl caffeates had a lower DPPH IC₅₀ (14-23 µM compared to CA, dibutyl hydroxy toluene (BHT and Vitamin C (24-51 µM, and significantly inhibited four human cancer cells (SW620, SW480, SGC7901 and HepG2 with inhibition ratio of 71.4-78.0% by a MTT assay. With regard to the induction period and acid value assays, methyl and butyl caffeates had higher abilities than BHT to restrain the oxidation process and improve the stability of edible oil. The addition of ethyl caffeate to oil allowed maintenance of a higher unsaturated fatty acid methyl ester content (68.53% at high temperatures. Overall, the alkyl caffeats with short chain length (n<5 assessed better oxidative stability than those with long chain length. To date, this is the first report to the correlations among the antioxidant activity, anticancer activity and oxidative stability of alkyl caffeates.

  9. School Pharmacist/School Environmental Hygienic Activities at School Site.

    Science.gov (United States)

    Muramatsu, Akiyoshi

    2016-01-01

    The "School Health and Safety Act" was enforced in April 2009 in Japan, and "school environmental health standards" were established by the Minister of Education, Culture, Sports, Science and Technology. In Article 24 of the Enforcement Regulations, the duties of the school pharmacist have been clarified; school pharmacists have charged with promoting health activities in schools and carrying out complete and regular checks based on the "school environmental health standards" in order to protect the health of students and staff. In supported of this, the school pharmacist group of Japan Pharmaceutical Association has created and distributed digital video discs (DVDs) on "check methods of school environmental health standards" as support material. We use the DVD to ensure the basic issues that school pharmacists deal with, such as objectives, criteria, and methods for each item to be checked, advice, and post-measures. We conduct various workshops and classes, and set up Q&A committees so that inquiries from members are answered with the help of such activities. In addition, school pharmacists try to improve the knowledge of the school staff on environmental hygiene during their in-service training. They also conduct "drug abuse prevention classes" at school and seek to improve knowledge and recognition of drugs, including "dangerous drugs".

  10. Effects of cobalt-substitution of the active zinc ion in thermolysin on its activity and active-site microenvironment.

    Science.gov (United States)

    Kuzuya, K; Inouye, K

    2001-12-01

    Thermolysin is remarkably activated in the presence of high concentrations (1-5 M) of neutral salts [Inouye, K. (1992) J. Biochem. 112, 335-340]. The activity is enhanced 13-15 times with 4 M NaCl at pH 7.0 and 25 degrees C. Substitution of the active site zinc with other transition metals alters the activity of thermolysin [Holmquist, B. and Vallee, B.L. (1974) J. Biol. Chem. 249, 4601-4607]. Cobalt is the most effective among the transition metals and doubles the activity toward N-[3-(2-furyl)acryloyl]-glycyl-L-leucine amide. In this study, the effect of NaCl on the activity of cobalt-substituted thermolysin was examined. Cobalt-substituted thermolysin, with 2.8-fold increased activity compared with the native enzyme, is further activated by the addition of NaCl in an exponential fashion, and the activity is enhanced 13-15 times at 4 M NaCl. The effects of cobalt-substitution and the addition of salt are independent of each other. The activity of cobalt-substituted thermolysin, expressed as k(cat)/K(m), is pH-dependent and controlled by at least two ionizing residues with pK(a) values of 6.0 and 7.8, the acidic pK(a) being slightly higher compared to 5.6 of the native enzyme. These pK(a) values remain constant in the presence of 4 M NaCl, indicating that the electrostatic environment of cobalt-substituted thermolysin is more stable than that of the native enzyme, the acidic pK(a) of which shifts remarkably from 5.6 to 6.7 at 4 M NaCl. Zincov, a competitive inhibitor, binds more tightly to the cobalt-substituted than to native thermolysin at pH 4.9-9.0, probably because of its preference for cobalt in the fivefold coordination. The cobalt substitution has been shown to be a favorable tool with which to explore the active-site microenvironment of thermolysin.

  11. Identification of the active site serine in pancreatic cholesterol esterase by chemical modification and site-specific mutagenesis.

    Science.gov (United States)

    DiPersio, L P; Fontaine, R N; Hui, D Y

    1990-10-05

    Chemical modification and site-specific mutagenesis approaches were used in this study to identify the active site serine residue of pancreatic cholesterol esterase. In the first approach, purified porcine pancreatic cholesterol esterase was covalently modified by incubation with [3H]diisopropylfluorophosphate (DFP). The radiolabeled cholesterol esterase was digested with CNBr, and the peptides were separated by high performance liquid chromatography. A single 3H-containing peptide was obtained for sequence determination. The results revealed the binding of DFP to a serine residue within the serine esterase homologous domain of the protein. Furthermore, the DFP-labeled serine was shown to correspond to serine residue 194 of rat cholesterol esterase (Kissel, J. A., Fontaine, R. N., Turck, C. W., Brockman, H. L., and Hui, D. Y. (1989) Biochim. Biophys. Acta 1006, 227-236). The codon for serine 194 in rat cholesterol esterase cDNA was then mutagenized to ACT or GCT to yield mutagenized cholesterol esterase with either threonine or alanine, instead of serine, at position 194. Expression of the mutagenized cDNA in COS-1 cells demonstrated that substitution of serine 194 with threonine or alanine abolished enzyme activity in hydrolyzing the water-soluble substrate, p-nitrophenyl butyrate, and the lipid substrates cholesteryl [14C]oleate and [14C] lysophosphatidylcholine. These studies definitively identified serine 194 in the catalytic site of pancreatic cholesterol esterase.

  12. Site preference of Zr in Ti 3 Al and phase stability of Ti 2 ZrAl

    Indian Academy of Sciences (India)

    Calculated values of equilibrium lattice parameters, heat of formation and bulk modulus of Ti2ZrAl are presented. The basis for the structural stability and bonding are analysed in terms of the density of states. Between the two possible 2-like structures, Ti2ZrAl shows enhanced stability for the one where Zr is substituted in ...

  13. Relationship between the CT Value and Cortical Bone Thickness at Implant Recipient Sites and Primary Implant Stability with Comparison of Different Implant Types.

    Science.gov (United States)

    Howashi, Miori; Tsukiyama, Yoshihiro; Ayukawa, Yasunori; Isoda-Akizuki, Kei; Kihara, Masafumi; Imai, Yu; Sogo, Motofumi; Koyano, Kiyoshi

    2016-02-01

    Studies have shown that bone quality at the implant recipient site can influence primary stability. The aims of this study were to explore the quantitative estimation of the primary stability of implants preoperatively using CT values and to examine the effect of different implant designs with recommended socket preparation on primary stability. Forty-four fresh porcine femoral heads were prepared. The bone surrounding implant sockets was preoperatively evaluated by helical CT. Forty-four implants (φ 4.3 × 10 mm), 22 straight and 22 tapered, were placed according to the manufacturer's instructions. The insertion torque value (ITV), implant stability quotient (ISQ), and removal torque value (RTV) were recorded as indicators of primary implant stability. Significant correlations and linear relationships were found between the CT value and ITV, ISQ, and RTV for both straight and tapered implants (Spearman's correlation coefficient, p < .001; linear regression analysis, p < .01). Tapered implants had a significantly higher ITV than straight implants (analysis of covariance, p < .01). Obtained results suggest that the primary stability of implants could be quantitatively estimated using the CT value preoperatively, indicating the CT value of bone surrounding an implant can contribute considerably to implant planning and design choice in clinical situations. © 2014 Wiley Periodicals, Inc.

  14. Mimicking the Active Sites of Organophosphorus Hydrolase on the Backbone of Graphene Oxide to Destroy Nerve Agent Simulants.

    Science.gov (United States)

    Ma, Xuejuan; Zhang, Lin; Xia, Mengfan; Li, Shuangqin; Zhang, Xiaohong; Zhang, Yaodong

    2017-06-28

    Recent global military events, such as the conflict in Syria, have emphasized the need to find effective strategies to rapidly destroy organophosphorus-based nerve agents. In this work, we designed active site-engineered graphene oxide (GO) via polymerization (polymer bead-GOs) as organophosphorus hydrolase (OPH) mimetic hotspots for the rapid degradation of nerve agents. This hybrid catalyst has a high total turnover frequency value of 0.65 s -1 and good stability (94.8% activity maintained after 5 cycles). Mechanism investigations suggested that the high catalytic performance could be attributed to the synergistic effect among the clusters of imidazole and the presence of - COOH groups on the GO surface and Zn 2+ .

  15. An Accessory Agonist Binding Site Promotes Activation of α4β2* Nicotinic Acetylcholine Receptors.

    Science.gov (United States)

    Wang, Jingyi; Kuryatov, Alexander; Sriram, Aarati; Jin, Zhuang; Kamenecka, Theodore M; Kenny, Paul J; Lindstrom, Jon

    2015-05-29

    Neuronal nicotinic acetylcholine receptors containing α4, β2, and sometimes other subunits (α4β2* nAChRs) regulate addictive and other behavioral effects of nicotine. These nAChRs exist in several stoichiometries, typically with two high affinity acetylcholine (ACh) binding sites at the interface of α4 and β2 subunits and a fifth accessory subunit. A third low affinity ACh binding site is formed when this accessory subunit is α4 but not if it is β2. Agonists selective for the accessory ACh site, such as 3-[3-(3-pyridyl)-1,2,4-oxadiazol-5-yl]benzonitrile (NS9283), cannot alone activate a nAChR but can facilitate more efficient activation in combination with agonists at the canonical α4β2 sites. We therefore suggest categorizing agonists according to their site selectivity. NS9283 binds to the accessory ACh binding site; thus it is termed an accessory site-selective agonist. We expressed (α4β2)2 concatamers in Xenopus oocytes with free accessory subunits to obtain defined nAChR stoichiometries and α4/accessory subunit interfaces. We show that α2, α3, α4, and α6 accessory subunits can form binding sites for ACh and NS9283 at interfaces with α4 subunits, but β2 and β4 accessory subunits cannot. To permit selective blockage of the accessory site, α4 threonine 126 located on the minus side of α4 that contributes to the accessory site, but not the α4β2 sites, was mutated to cysteine. Alkylation of this cysteine with a thioreactive reagent blocked activity of ACh and NS9283 at the accessory site. Accessory agonist binding sites are promising drug targets. © 2015 by The American Society for Biochemistry and Molecular Biology, Inc.

  16. Stability analysis and active damping for LLCL-filter based grid-connected inverters

    DEFF Research Database (Denmark)

    Huang, Min; Blaabjerg, Frede; Loh, Poh Chiang

    2014-01-01

    A higher order passive power filter (LLCL-filter) for the grid-tied inverter is becoming attractive for the industrial applications due to the possibility to reduce the cost of the copper and the magnetic material. To avoid the well-known stability problems of the LLCL-filter it is requested to use...... either passive or active damping methods. This paper analyzes the stability when damping is required and when damping is not necessary considering sampling and transport delay. Basic LLCL resonance damping properties of different feedback states are also studied. Then an active damping method which...... is using the capacitor current feedback for LLCL-filter is introduced. Based on this method, a design procedure for the control method is given. Last, both simulation and experimental results are provided to validate the theoretical analysis of this paper....

  17. Improvement of the directional stability of passenger car trailer couplings with actively controlled steering

    Science.gov (United States)

    Desens, Jens

    The stabilization of pendulum oscillations of passenger car trailer couplings, using active steering, was examined. A linear model of the couplings was presented. Each axle was provided with a controller. The controllers were optimized, with regard to necessary sensors, in order to minimize costs. The rear and the front axles were provided with a control unit in order to compute the potential prevailing in the active steering of several axles. It was shown that the passenger car rear axle was the most suitable for coupling stabilization. The experiment was simulated, using a complex coupling model. The developed controller allowed the passenger car trailer to be driven at a speed higher than 150 km per hour.

  18. Absolute exponential stability of recurrent neural networks with Lipschitz-continuous activation functions and time delays.

    Science.gov (United States)

    Cao, Jinde; Wang, Jun

    2004-04-01

    This paper investigates the absolute exponential stability of a general class of delayed neural networks, which require the activation functions to be partially Lipschitz continuous and monotone nondecreasing only, but not necessarily differentiable or bounded. Three new sufficient conditions are derived to ascertain whether or not the equilibrium points of the delayed neural networks with additively diagonally stable interconnection matrices are absolutely exponentially stable by using delay Halanay-type inequality and Lyapunov function. The stability criteria are also suitable for delayed optimization neural networks and delayed cellular neural networks whose activation functions are often nondifferentiable or unbounded. The results herein answer a question: if a neural network without any delay is absolutely exponentially stable, then under what additional conditions, the neural networks with delay is also absolutely exponentially stable.

  19. Stability Analysis for Isolated AC Microgrids Based on PV-Active Generators

    DEFF Research Database (Denmark)

    Aldana, Nelson Leonardo Diaz; Coelho, Ernane A. A.; Quintero, Juan Carlos Vasquez

    2015-01-01

    for interconnecting several different distributed generators in parallel to a common bus, whose parameters determine the stability and damping of the microgrid operation. In this paper, a small-signal stability analysis is applied to an isolated AC microgrid composed of (PV+ESS) active generators, regarding three......The current trend in isolated microgrids is oriented to distributed renewable energy generators, such as photovoltaic (PV) generators and their corresponding distributed energy storage systems (ESS) as an unit denoted as active generator (PV+ESS). In an isolated microgrid, every distributed...... generator (ESS or PV) may operate in two operation modes (grid-forming or grid-following) in accordance to specific operational conditions. Nevertheless, at least one distributed generator should assume the regulation of the common bus, and seamless transition between operation modes should be ensured...

  20. Stability of Anthocyanins from Rubus glaucus and Solanum betaceum as affected by Temperature and Water Activity

    OpenAIRE

    Garzon Monroy Gloria Astrid; Castaño Maria Paola; Olaya Clara Marcela

    2009-01-01

    The stability of sprayed-dried microencapsulated anthocyanins from Andes berry (Rubus glaucus) and Tamarillo (Solanum betaceum), as affected by storage time, water activity (Aw) and temperature was compared. The fruits were osmotically dehydrated with ethanol and the anthocyanin extract was microencapsulated with maltodextrin DE 20 by spray drying. Half life o...

  1. Rotation in a reversed field pinch with active feedback stabilization of resistive wall modes

    Science.gov (United States)

    Cecconello, M.; Menmuir, S.; Brunsell, P. R.; Kuldkepp, M.

    2006-09-01

    Active feedback stabilization of multiple resistive wall modes (RWMs) has been successfully proven in the EXTRAP T2R reversed field pinch. One of the features of plasma discharges operated with active feedback stabilization, in addition to the prolongation of the plasma discharge, is the sustainment of the plasma rotation. Sustained rotation is observed both for the internally resonant tearing modes (TMs) and the intrinsic impurity oxygen ions. Good quantitative agreement between the toroidal rotation velocities of both is found: the toroidal rotation is characterized by an acceleration phase followed, after one wall time, by a deceleration phase that is slower than in standard discharges. The TMs and the impurity ions rotate in the same poloidal direction with also similar velocities. Poloidal and toroidal velocities have comparable amplitudes and a simple model of their radial profile reproduces the main features of the helical angular phase velocity. RWMs feedback does not qualitatively change the TMs behaviour and typical phenomena such as the dynamo and the 'slinky' are still observed. The improved sustainment of the plasma and TMs rotation occurs also when feedback only acts on internally non-resonant RWMs. This may be due to an indirect positive effect, through non-linear coupling between TMs and RWMs, of feedback on the TMs or to a reduced plasma-wall interaction affecting the plasma flow rotation. Electromagnetic torque calculations show that with active feedback stabilization the TMs amplitude remains well below the locking threshold condition for a thick shell. Finally, it is suggested that active feedback stabilization of RWMs and current profile control techniques can be employed simultaneously thus improving both the plasma duration and its confinement properties.

  2. Rotation in a reversed field pinch with active feedback stabilization of resistive wall modes

    Energy Technology Data Exchange (ETDEWEB)

    Cecconello, M [Division of Fusion Plasma Physics, Association EURATOM -VR, Alfven Laboratory, School of Electrical Engineering, Royal Institute of Technology KTH, SE-10044 Stockholm (Sweden); Menmuir, S [Department of Physics, Association EURATOM -VR, School of Engineering Science, Royal Institute of Technology KTH, SE-10691 Stockhom (Sweden); Brunsell, P R [Division of Fusion Plasma Physics, Association EURATOM -VR, Alfven Laboratory, School of Electrical Engineering, Royal Institute of Technology KTH, SE-10044 Stockholm (Sweden); Kuldkepp, M [Department of Physics, Association EURATOM -VR, School of Engineering Science, Royal Institute of Technology KTH, SE-10691 Stockhom (Sweden)

    2006-09-15

    Active feedback stabilization of multiple resistive wall modes (RWMs) has been successfully proven in the EXTRAP T2R reversed field pinch. One of the features of plasma discharges operated with active feedback stabilization, in addition to the prolongation of the plasma discharge, is the sustainment of the plasma rotation. Sustained rotation is observed both for the internally resonant tearing modes (TMs) and the intrinsic impurity oxygen ions. Good quantitative agreement between the toroidal rotation velocities of both is found: the toroidal rotation is characterized by an acceleration phase followed, after one wall time, by a deceleration phase that is slower than in standard discharges. The TMs and the impurity ions rotate in the same poloidal direction with also similar velocities. Poloidal and toroidal velocities have comparable amplitudes and a simple model of their radial profile reproduces the main features of the helical angular phase velocity. RWMs feedback does not qualitatively change the TMs behaviour and typical phenomena such as the dynamo and the 'slinky' are still observed. The improved sustainment of the plasma and TMs rotation occurs also when feedback only acts on internally non-resonant RWMs. This may be due to an indirect positive effect, through non-linear coupling between TMs and RWMs, of feedback on the TMs or to a reduced plasma-wall interaction affecting the plasma flow rotation. Electromagnetic torque calculations show that with active feedback stabilization the TMs amplitude remains well below the locking threshold condition for a thick shell. Finally, it is suggested that active feedback stabilization of RWMs and current profile control techniques can be employed simultaneously thus improving both the plasma duration and its confinement properties.

  3. Rotation in a reversed field pinch with active feedback stabilization of resistive wall modes

    International Nuclear Information System (INIS)

    Cecconello, M; Menmuir, S; Brunsell, P R; Kuldkepp, M

    2006-01-01

    Active feedback stabilization of multiple resistive wall modes (RWMs) has been successfully proven in the EXTRAP T2R reversed field pinch. One of the features of plasma discharges operated with active feedback stabilization, in addition to the prolongation of the plasma discharge, is the sustainment of the plasma rotation. Sustained rotation is observed both for the internally resonant tearing modes (TMs) and the intrinsic impurity oxygen ions. Good quantitative agreement between the toroidal rotation velocities of both is found: the toroidal rotation is characterized by an acceleration phase followed, after one wall time, by a deceleration phase that is slower than in standard discharges. The TMs and the impurity ions rotate in the same poloidal direction with also similar velocities. Poloidal and toroidal velocities have comparable amplitudes and a simple model of their radial profile reproduces the main features of the helical angular phase velocity. RWMs feedback does not qualitatively change the TMs behaviour and typical phenomena such as the dynamo and the 'slinky' are still observed. The improved sustainment of the plasma and TMs rotation occurs also when feedback only acts on internally non-resonant RWMs. This may be due to an indirect positive effect, through non-linear coupling between TMs and RWMs, of feedback on the TMs or to a reduced plasma-wall interaction affecting the plasma flow rotation. Electromagnetic torque calculations show that with active feedback stabilization the TMs amplitude remains well below the locking threshold condition for a thick shell. Finally, it is suggested that active feedback stabilization of RWMs and current profile control techniques can be employed simultaneously thus improving both the plasma duration and its confinement properties

  4. Engineering a highly active thermophilic ?-glucosidase to enhance its pH stability and saccharification performance

    OpenAIRE

    Xia, Wei; Xu, Xinxin; Qian, Lichun; Shi, Pengjun; Bai, Yingguo; Luo, Huiying; Ma, Rui; Yao, Bin

    2016-01-01

    Background ?-Glucosidase is an important member of the biomass-degrading enzyme system, and plays vital roles in enzymatic saccharification for biofuels production. Candidates with high activity and great stability over high temperature and varied pHs are always preferred in industrial practice. To achieve cost-effective biomass conversion, exploring natural enzymes, developing high level expression systems and engineering superior mutants are effective approaches commonly used. Results A new...

  5. Physical and chemical characterization of active pharmaceutical ingredients in the framework of preformulation and stability studies

    OpenAIRE

    Gana , Inès

    2015-01-01

    The development of a drug for a given therapeutic target requires several steps, which can be summarized by drug screening, a preclinical phase and a number of clinical phases. These steps allow the selection of an active substance and a verification of its therapeutic efficacy and toxicological safety. The latter two criteria define the quality of the drug, which once demonstrated, must be guaranteed throughout its shelf life. Quality is assessed through stability studies that are carried ou...

  6. A coexisting fungal-bacterial community stabilizes soil decomposition activity in a microcosm experiment.

    Directory of Open Access Journals (Sweden)

    Masayuki Ushio

    Full Text Available How diversity influences the stability of a community function is a major question in ecology. However, only limited empirical investigations of the diversity-stability relationship in soil microbial communities have been undertaken, despite the fundamental role of microbial communities in driving carbon and nutrient cycling in terrestrial ecosystems. In this study, we conducted a microcosm experiment to investigate the relationship between microbial diversity and stability of soil decomposition activities against changes in decomposition substrate quality by manipulating microbial community using selective biocides. We found that soil respiration rates and degradation enzyme activities by a coexisting fungal and bacterial community (a taxonomically diverse community are more stable against changes in substrate quality (plant leaf materials than those of a fungi-dominated or a bacteria-dominated community (less diverse community. Flexible changes in the microbial community composition and/or physiological state in the coexisting community against changes in substrate quality, as inferred by the soil lipid profile, may be the mechanism underlying this positive diversity-stability relationship. Our experiment demonstrated that the previously found positive diversity-stability relationship could also be valid in the soil microbial community. Our results also imply that the functional/taxonomic diversity and community ecology of soil microbes should be incorporated into the context of climate-ecosystem feedbacks. Changes in substrate quality, which could be induced by climate change, have impacts on decomposition process and carbon dioxide emission from soils, but such impacts may be attenuated by the functional diversity of soil microbial communities.

  7. Remedial action plan and site conceptual design for stabilization of the inactive uranium mill tailings sites at Rifle, Colorado. Appendix D, Final report

    International Nuclear Information System (INIS)

    1992-02-01

    This appendix assesses the present conditions and data gathered about the two designated inactive uranium mill tailings sites near Rifle, Colorado, and the proposed disposal site six miles north of Rifle in the area of Estes Gulch. It consolidates available engineering, radiological, geotechnical, hydrological, meteorological, and other information pertinent to the design of the Remedial Action Plan (RAP). The data characterize conditions at the mill, tailings, and disposal site so that the Remedial Action Contractor (RAC) may complete final designs for the remedial actions

  8. Remedial action plan and site conceptual design for stabilization of the inactive uranium mill tailings sites at Rifle, Colorado. Appendix D, Final report

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1992-02-01

    This appendix assesses the present conditions and data gathered about the two designated inactive uranium mill tailings sites near Rifle, Colorado, and the proposed disposal site six miles north of Rifle in the area of Estes Gulch. It consolidates available engineering, radiological, geotechnical, hydrological, meteorological, and other information pertinent to the design of the Remedial Action Plan (RAP). The data characterize conditions at the mill, tailings, and disposal site so that the Remedial Action Contractor (RAC) may complete final designs for the remedial actions.

  9. Thermal stability and kinetic constants for 129 variants of a family 1 glycoside hydrolase reveal that enzyme activity and stability can be separately designed.

    Directory of Open Access Journals (Sweden)

    Dylan Alexander Carlin

    Full Text Available Accurate modeling of enzyme activity and stability is an important goal of the protein engineering community. However, studies seeking to evaluate current progress are limited by small data sets of quantitative kinetic constants and thermal stability measurements. Here, we report quantitative measurements of soluble protein expression in E. coli, thermal stability, and Michaelis-Menten constants (kcat, KM, and kcat/KM for 129 designed mutants of a glycoside hydrolase. Statistical analyses reveal that functional Tm is independent of kcat, KM, and kcat/KM in this system, illustrating that an individual mutation can modulate these functional parameters independently. In addition, this data set is used to evaluate computational predictions of protein stability using the established Rosetta and FoldX algorithms. Predictions for both are found to correlate only weakly with experimental measurements, suggesting improvements are needed in the underlying algorithms.

  10. Neutron activation analysis to the profile surface sediments from several sites on the Havana Bay

    International Nuclear Information System (INIS)

    Diaz Riso, O.; Gelen, A.; Lopez, N.; Gonzalez, H.; Manso, M.V.; Graciano, A.M.; Nogueira, C.A.; Beltran, J.; Soto, J.

    2003-01-01

    Instrumental neutron activation analysis (INAA) technique was employed to analyze the surface sediments from several sites on the Havana Bay, Cuba. Measurements of heavy and trace elements in the sediments are reported. The results show that the concentration of the elements is site dependent. The data suggest that an anthropogenic input into the bay from domestic sewage and industries occurred

  11. 10 CFR 60.18 - Review of site characterization activities. 2

    Science.gov (United States)

    2010-01-01

    ... 10 Energy 2 2010-01-01 2010-01-01 false Review of site characterization activities. 2 60.18 Section 60.18 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) DISPOSAL OF HIGH-LEVEL RADIOACTIVE WASTES... Atomic Energy Act of 1954, as amended. Accordingly, neither the issuance of a site characterization...

  12. 10 CFR 63.16 - Review of site characterization activities. 2

    Science.gov (United States)

    2010-01-01

    ... 10 Energy 2 2010-01-01 2010-01-01 false Review of site characterization activities. 2 63.16 Section 63.16 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) DISPOSAL OF HIGH-LEVEL RADIOACTIVE WASTES... recommendations or stating objections to DOE's site characterization program. The Director shall invite public...

  13. Facet-dependent activity and stability of Co₃O₄ nanocrystals towards the oxygen evolution reaction.

    Science.gov (United States)

    Chen, Zhu; Kronawitter, Coleman X; Koel, Bruce E

    2015-11-21

    The electrocatalytic activities and stabilities of spinel cobalt oxides with different morphologies have been investigated for the oxygen evolution reaction (OER) in an alkaline environment. Spinel cobalt oxide nanoparticles with well-defined cubic and octahedral morphologies were prepared, which predominantly expose the (100) and (111) surfaces, respectively. The OER activity of spinel cobalt oxide, measured in terms of current density, increases with higher relative proportion of the (111) surface, which can be attributed to the higher density of cobalt ions on the (111) surface compared to that on the (100) surface. The surfaces of cobalt oxide nanocubes are slighted reduced compared to those of nanooctahedra prior to OER testing. Based on chronoamperometry experiments, the nanocubes exhibited higher stability compared to the nanooctahedra, which could be due to the lower surface energy of the (100) surface compared to the (111) surface. The dependence of OER activity and stability on spinel cobalt oxide crystal facets demonstrates the importance of surface orientation in catalyst performance optimization.

  14. Stability and Activity of Non-Noble-Metal-Based Catalysts Toward the Hydrogen Evolution Reaction.

    Science.gov (United States)

    Ledendecker, Marc; Mondschein, Jared S; Kasian, Olga; Geiger, Simon; Göhl, Daniel; Schalenbach, Max; Zeradjanin, Aleksandar; Cherevko, Serhiy; Schaak, Raymond E; Mayrhofer, Karl

    2017-08-07

    A fundamental understanding of the behavior of non-noble based materials toward the hydrogen evolution reaction is crucial for the successful implementation into practical devices. Through the implementation of a highly sensitive inductively coupled plasma mass spectrometer coupled to a scanning flow cell, the activity and stability of non-noble electrocatalysts is presented. The studied catalysts comprise a range of compositions, including metal carbides (WC), sulfides (MoS 2 ), phosphides (Ni 5 P 4 , Co 2 P), and their base metals (W, Ni, Mo, Co); their activity, stability, and degradation behavior was elaborated and compared to the state-of-the-art catalyst platinum. The non-noble materials are stable at HER potentials but dissolve substantially when no current is flowing. Through pre- and post-characterization of the catalysts, explanations of their stability (thermodynamics and kinetics) are discussed, challenges for the application in real devices are analyzed, and strategies for circumventing dissolution are suggested. The precise correlation of metal dissolution with applied potential/current density allows for narrowing down suitable material choices as replacement for precious group metals as for example, platinum and opens up new ways in finding cost-efficient, active, and stable new-generation electrocatalysts. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  15. Hammerhead ribozyme activity and oligonucleotide duplex stability in mixed solutions of water and organic compounds

    Directory of Open Access Journals (Sweden)

    Shu-ichi Nakano

    2014-01-01

    Full Text Available Nucleic acids are useful for biomedical targeting and sensing applications in which the molecular environment is different from that of a dilute aqueous solution. In this study, the influence of various types of mixed solutions of water and water-soluble organic compounds on RNA was investigated by measuring the catalytic activity of the hammerhead ribozyme and the thermodynamic stability of an oligonucleotide duplex. The compounds with a net neutral charge, such as poly(ethylene glycol, small primary alcohols, amide compounds, and aprotic solvent molecules, added at high concentrations changed the ribozyme-catalyzed RNA cleavage rate, with the magnitude of the effect dependent on the NaCl concentration. These compounds also changed the thermodynamic stability of RNA base pairs of an oligonucleotide duplex and its dependence on the NaCl concentration. Specific interactions with RNA molecules and reduced water activity could account for the inhibiting effects on the ribozyme catalysis and destabilizing effects on the duplex stability. The salt concentration dependence data correlated with the dielectric constant, but not with water activity, viscosity, and the size of organic compounds. This observation suggests the significance of the dielectric constant effects on the RNA reactions under molecular crowding conditions created by organic compounds.

  16. Regulation of xanthine oxidase activity by substrates at active sites via cooperative interactions between catalytic subunits: implication to drug pharmacokinetics.

    Science.gov (United States)

    Tai, L A; Hwang, K C

    2011-01-01

    Three xanthine oxidase substrates (i.e., xanthine, adenine, and 2-amino-4-hydroxypterin) show a "substrate inhibition" pattern (i.e., slower turnover rates at higher substrate concentrations), whereas another two substrates (i.e., xanthopterin and lumazine) show a "substrate activation" pattern (i.e., higher turnover rates at higher substrate concentrations). Binding of a 6-formylpterin at one of the two xanthine oxidase active sites slows down the turnover rate of xanthine at the adjacent active site from 17.0 s(-1) to 10.5 s(-1), and converts the V-[S] plot from "substrate inhibition" pattern to a classical Michaelis-Menten hyperbolic saturation pattern. In contrast, binding of xanthine at an active site accelerates the turnover rate of 6-formylpterin at the neighboring active site. The experimental results demonstrate that a substrate can regulate the activity of xanthine oxidase via binding at the active sites; or a xanthine oxidase catalytic subunit can simultaneously serve as a regulatory unit. Theoretical simulation based on the velocity equation derived from the extended Michaelis-Menten model shows that the substrate inhibition and the substrate activation behavior in the V-[S] plots could be obtained by introducing cooperative interactions between two catalytic subunits in homodimeric enzymes. The current work confirms that there exist very strong cooperative interactions between the two catalytic subunits of xanthine oxidase.

  17. The balance of flexibility and rigidity in the active site residues of hen egg white lysozyme

    International Nuclear Information System (INIS)

    Qi Jian-Xun; Jiang Fan

    2011-01-01

    The crystallographic temperature factors (B factor) of individual atoms contain important information about the thermal motion of the atoms in a macromolecule. Previously the theory of flexibility of active site has been established based on the observation that the enzyme activity is sensitive to low concentration denaturing agents. It has been found that the loss of enzyme activity occurs well before the disruption of the three-dimensional structural scaffold of the enzyme. To test the theory of conformational flexibility of enzyme active site, crystal structures were perturbed by soaking in low concentration guanidine hydrochloride solutions. It was found that many lysozyme crystals tested could still diffract until the concentration of guanidine hydrochloride reached 3 M. It was also found that the B factors averaged over individually collected data sets were more accurate. Thus it suggested that accurate measurement of crystal temperature factors could be achieved for medium-high or even medium resolution crystals by averaging over multiple data sets. Furthermore, we found that the correctly predicted active sites included not only the more flexible residues, but also some more rigid residues. Both the flexible and the rigid residues in the active site played an important role in forming the active site residue network, covering the majority of the substrate binding residues. Therefore, this experimental prediction method may be useful for characterizing the binding site and the function of a protein, such as drug targeting. (interdisciplinary physics and related areas of science and technology)

  18. 1993 annual report of hazardous waste activities for the Oak Ridge K-25 site

    Energy Technology Data Exchange (ETDEWEB)

    1994-02-01

    This report is a detailed listing of all of the Hazardous Waste activities occurring at Martin Marietta`s K-25 site. Contained herein are hazardous waste notification forms, waste stream reports, generator fee forms and various TSDR reports.

  19. 1993 annual report of hazardous waste activities for the Oak Ridge K-25 site

    International Nuclear Information System (INIS)

    1994-02-01

    This report is a detailed listing of all of the Hazardous Waste activities occurring at Martin Marietta's K-25 site. Contained herein are hazardous waste notification forms, waste stream reports, generator fee forms and various TSDR reports

  20. Modifications to the remedial action plan and site design for stabilization of the inactive Uranium Mill Tailings Site at Green River, Utah

    International Nuclear Information System (INIS)

    1994-09-01

    Modifications to the water resources protection strategy detailed in the remedial action plan for the Green River, Utah, disposal site are presented. The modifications are based on new information, including ground water quality data collected after remedial action was completed and on a revised assessment of disposal cell design features, surface conditions, and site hydrogeology. The modifications will result in compliance with the U.S. EPA proposed ground water standards (52 FR 36000 (1987))

  1. Catalytic activity and stability of xanthine oxidase in aqueous-organic mixtures.

    Science.gov (United States)

    Rashidi, M R; Soruraddin, M H; Taherzadeh, F; Jouyban, A

    2009-01-01

    In the present study, bovine milk xanthine oxidase activity in various aqueous-organic mixtures and the effects of pH, temperature, and lyophilization on the enzyme activity have been investigated. The enzyme was incubated with xanthine as the substrate in Sorenson's phosphate buffer (pH 7.0) containing 0.1 mM EDTA, and the activity was determined spectrophotometrically in the absence and presence of different fractions of nine water-miscible organic solvents at 27-50 degrees C and at different pH values ranging from 6 to 9. The organic solvents reduced the enzyme activity to different extents. In spite of these inhibitory effects, the enzyme showed relatively good stability in the aqueous-organic mixtures compared with the aqueous medium. A significant increase in the activity of the lyophilized enzyme was observed in pure organic solvents.

  2. Active control stabilization of pelvic position in the transverse plane: an evaluation of soccer players' performance.

    Science.gov (United States)

    Santos, Thiago Ribeiro Teles; Andrade, Juliana Alves de; Silva, Bárbara Lopes da; Garcia, Alysson Francisco Alves; Persichini Filho, José Gaspar Wild; Ocarino, Juliana de Melo; Silva, Paula Lanna

    2014-08-01

    To describe the capability of soccer players to stabilize pelvic position actively in the transverse plane; and, to evaluate the influence of lower limb dominance, length of exposure to soccer practice, and field position on pelvic stabilization capability. Cross-sectional. Sixty-eight soccer players from under-15 (U-15) and professional categories. Magnitude and asymmetry of pelvic tilt in the transverse plane, evaluated using the bridge test with unilateral knee extension. The magnitude of pelvic tilt did not differ between dominant and non-dominant sides, suggesting absence of relative asymmetry. However, there was difference between the sides of greater and lesser magnitude of pelvic tilt, indicating presence of absolute asymmetry. Players with shorter length of exposure to soccer practice (U-15 group) had greater pelvic tilt than players with longer length of exposure (professional group). There was no association of field position with the magnitude and asymmetry of pelvic tilt. Soccer players showed asymmetry in pelvic stabilization capability that was unrelated to lower limb dominance or field position. Athletes with longer length of exposure to soccer practice present better capability to stabilize the pelvis in the transverse plane than those with shorter length of exposure to soccer practice. Copyright © 2013 Elsevier Ltd. All rights reserved.

  3. Development and flight evaluation of an augmented stability active controls concept: Executive summary

    Science.gov (United States)

    Guinn, W. A.

    1982-01-01

    A pitch active control system (PACS) was developed and flight tested on a wide body jet transport (L-1011) with a flying horizontal stabilizer. Two dual channel digital computers and the associated software provide command signals to a dual channel series servo which controls the stabilizer power actuators. Input sensor signals to the computer are pitch rate, column trim position, and dynamic pressure. Control laws are given for the PACS and the system architecture is defined. Discussions are given regarding piloted flight simulation and vehicle system simulation and vehicle system simulation tests that are performed to verify control laws and system operation prior to installation on the aircraft. Modifications to the basic aircraft included installation of the PACS, addition of a c.g. management system to provide a c.g. range from 25 to 39% mac, and downrigging of the geared elevator to provide the required nose down control authority for aft c.g. flight test conditions. Three pilots used the Cooper-Harper Rating Scale to judge flying qualities of the aircraft with PACS on and off. The handling qualities with the c.g. at 39% mac (41% stability margin) and PACS operating were judged to be as good as the handling qualities with the c.g. at 25% mac (+15% stability margin) and PACS off.

  4. Stabilization of enzymes by multipoint covalent immobilization on supports activated with glyoxyl groups.

    Science.gov (United States)

    López-Gallego, Fernando; Fernandez-Lorente, Gloria; Rocha-Martin, Javier; Bolivar, Juan M; Mateo, Cesar; Guisan, Jose M

    2013-01-01

    Stabilization of enzymes via immobilization techniques is a valuable approach in order to convert a necessary protocol (immobilization) into a very interesting tool to improve key enzyme properties (stabilization). Multipoint covalent attachment of each immobilized enzyme molecule may promote a very interesting stabilizing effect. The relative distances among all enzyme residues involved in immobilization has to remain unaltered during any conformational change induced by any distorting agent. Amino groups are very interesting nucleophiles placed on protein surfaces. The immobilization of enzyme through the region having the highest amount of amino groups (Lys residues) is key for a successful stabilization. Glyoxyl groups are small aliphatic aldehydes that form very unstable Schiff's bases with amino groups and they do not seem to be useful for enzyme immobilization at neutral pH. However, under alkaline conditions, glyoxyl supports are able to immobilize enzymes via a first multipoint covalent immobilization through the region having the highest amount of Lysine groups. Activation of supports with a high surface density of glyoxyl groups and the performance of very intense enzyme-support multipoint covalent attachments are here described.

  5. Structure-Activity Relationship Analysis of the Thermal Stabilities of Nitroaromatic Compounds Following Different Decomposition Mechanisms.

    Science.gov (United States)

    Li, Jiazhong; Liu, Huanxiang; Huo, Xing; Gramatica, Paola

    2013-02-01

    The decomposition behavior of energetic materials is very important for the safety problems concerning their production, transportation, use and storage, because molecular decomposition is intimately connected to their explosive properties. Nitroaromatic compounds, particularly nitrobenzene derivatives, are often considered as prototypical energetic molecules, and some of them are commonly used as high explosives. Quantitative structure-activity relationship (QSAR) represents a potential tool for predicting the thermal stability properties of energetic materials. But it is reported that constructing general reliable models to predict their stability and their potential explosive properties is a very difficult task. In this work, we make our efforts to investigate the relationship between the molecular structures and corresponding thermal stabilities of 77 nitrobenzene derivatives with various substituent functional groups (in ortho, meta and/or para positions). The proposed best MLR model, developed by the new software QSARINS, based on Genetic Algorithm for variable selection and with various validation tools, is robust, stable and predictive with R(2) of 0.86, QLOO (2) of 0.79 and CCC of 0.90. The results indicated that, though difficult, it is possible to build predictive, externally validated QSAR models to estimate the thermal stability of nitroaromatic compounds. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  6. Activation of TREK-1, but Not TREK-2, Channel by Mood Stabilizers

    Directory of Open Access Journals (Sweden)

    Eun-Jin Kim

    2017-11-01

    Full Text Available Earlier studies have demonstrated that the tandem pore domain weak inward rectifying K+ channel (TWIK-related K+ (TREK-1 channel is inhibited by antidepressants and is associated with major depression. However, little is known about the effect of mood stabilizers that are commonly used for treatment of bipolar disorder on TREK channels, members of the two-pore domain K+ (K2P channel family. This study sought to investigate the effect of mood stabilizers on TREK-1 and TREK-2 channels. HEK-293A cells were transfected with human TREK-1 or TREK-2 DNA. The effect of mood stabilizers on TREK-1 and TREK-2 was studied using the patch clamp technique. Changes in TREK protein expression by mood stabilizers were studied in the HT-22 mouse hippocampal neuronal cells using western blot analysis. Lithium chloride (LiCl, 1 mM, gabapentin (100 μM, valproate (100 μM, and carbamazepine (100 μM increased TREK-1 currents by 31 ± 14%, 25 ± 11%, 28 ± 12%, and 72 ± 12%, respectively, whereas they had no effect on TREK-2 channel activity. In addition, western blot analysis showed LiCl and carbamazepine slightly upregulated TREK-1 expression, but not TREK-2 in the HT-22 cells. These results suggest that TREK-1 could be a potential therapeutic target for treatment of bipolar disorders as well as depression, while TREK-2 is a target well suited for treatment of major depression.

  7. Treatment of coke-oven wastewater with the powdered activated carbon-contact stabilization activated sludge process. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Suidan, M.T.; Deady, M.A.; Gee, C.S.

    1983-11-01

    The objective of the study was to determine optimum parameters for the operation of an innovative process train used in the treatment of coke-over wastewater. The treatment process train consisted of a contact-stabilization activated sludge system with powdered activated carbon (PAC) addition, followed by activated sludge nitrification, followed by denitrification in an anoxic filter. The control and operating parameters evaluated during the study were: (a) the average mixed-liquor PAC concentration maintained in the contact-stabilization system, (b) the solids retention time practiced in the contact-stabilization system, and (c) the hydraulic detention time maintained in the contact aeration tank. Three identical treatement process trains were constructed and employed in this study. The coke-oven wastewater used for this investigation was fed to the treatment units at 30% strength. The first part of the study was devoted to determining the interactions between the mixed liquor PAC concentration and the solids retention time in the contact-stabilization tanks. Results showed that optimum overall system performance is attainable when the highest sludge age (30 day) and highest mixed liquor PAC concentration were practiced. During the second phase of the study, all three systems were operated at a 30 day solids retention time while different detention times of 1, 2/3 and 1/3 day were evaluated in the contact tank. PAC addition rates were maintained at the former levels and, consequently, reduced contact times entailed higher mixed liquor carbon concentrations. Once again, the system receiving the highest PAC addition rate of PAC exhibited the best overall performance. This system exhibited no deterioration in process performance as a result of decreased contact detention time. 72 references, 41 figures, 24 tables.

  8. Understanding the catalytic benefits of multi=metallic active sites in microporous aluminophosphates

    OpenAIRE

    Potter, Matthew

    2015-01-01

    Structure-property correlations, which direct the formation of specific active-acid sites, in nanoporous materials have been explored with the aim to further the notion of rational catalyst design. It is demonstrated that the influence of the specific zeotype framework extends beyond modulating Brønsted acidity, with the framework topology playing a fundamental role in reaction kinetics. The structural integrity and nature of the active site has been probed using a combined catalysis and mult...

  9. High-Q nested resonator in an actively stabilized optomechanical cavity

    Science.gov (United States)

    Buters, F. M.; Heeck, K.; Eerkens, H. J.; Weaver, M. J.; Luna, F.; de Man, S.; Bouwmeester, D.

    2017-03-01

    Experiments involving micro- and nanomechanical resonators need to be carefully designed to reduce mechanical environmental noise. A small scale on-chip approach is to add a resonator to the system as a mechanical low-pass filter. However, the inherent low frequency of the low-pass filter causes the system to be easily excited mechanically. We solve this problem by applying active feedback to the resonator, thereby minimizing the motion with respect to the front mirror of an optomechanical cavity. Not only does this method actively stabilize the cavity length but it also retains the on-chip vibration isolation.

  10. XAFS Study of the Photo-Active Site of Mo/MCM-41

    International Nuclear Information System (INIS)

    Miyamoto, Daisuke; Ichikuni, Nobuyuki; Shimazu, Shogo

    2007-01-01

    An Mo/MCM-41 catalyst was prepared and used for study of propene and 1-butene photo-metathesis reactions. XAFS analysis revealed that hydrogen reduction leads to a decreased role for the Mo=O site. The Mo-O site plays an important role for the olefin photo-metathesis reaction on the H2 reduced Mo/MCM-41. From EXAFS analysis, the active site of photo-metathesis reaction is the Mo=O part for oxidized Mo/MCM-41, whereas it is the Mo-O site for reduced Mo/MCM-41

  11. Antibacterial activity of silver nanoparticles stabilized on tannin-grafted collagen fiber

    International Nuclear Information System (INIS)

    He Li; Gao Siying; Wu Hao; Liao Xuepin; He Qiang; Shi Bi

    2012-01-01

    Bayberry tannin (BT), a typical plant polyphenol, was grafted on collagen fiber (CF) in different mass ratios. Subsequently, the BT-grafted CF (BT-CF) was used as carrier and stabilizer to prepare BT-CF stabilized silver nanoparticles (BT-CF-AgNPs). Scanning Electron Microscopy image of BT-CF-AgNPs showed that the BT-CF-AgNPs was in ordered fibrous state. X-ray Diffraction patterns and Transmission Electron Microscopy images offered evidence that the Ag nanoparticles were well dispersed on BT-CF. Fourier Transform-Infrared Spectroscopy (FTIR) and X-ray Photoelectron Spectroscopy (XPS) investigations revealed that the Ag NPs were stabilized by the phenolic hydroxyls and quinones of BT on CF through electron donation/acception interaction. Antibacterial experiments demonstrated that BT-CF-AgNPs exhibited high antibacterial activity. When cell suspensions of Escherichia coli and Staphylococcus aureus (10 4 –10 5 cfu/mL) were contacted with BT 0.19 -CF-AgNPs (mass ratio of BT to CF = 0.19, conc. of Ag = 8 μg/mL) at 310 K under constant shaking, the number of cells went down to zero within 2 h. In addition, the minimal inhibitory concentration of BT 0.19 -CF-AgNPs against Escherichia coli, Staphylococcus aureus, Penicillium glaucum and Saccharomyces cerevisiae was 2 μg/mL, 4 μg/mL, 6 μg/mL and 12 μg/mL Ag, respectively. During recycling use, the antibacterial activity of BT 0.19 -CF-AgNPs against Escherichia coli can last for 5 cycles. These facts suggest that BT-CF-AgNPs can be used as a new and effective antibacterial agent. - Highlights: ► Bayberry tannin-grafted collagen fiber can be acted as carrier and stabilizer for the preparation of nano-silver (AgNPs) with different particle size. ► Bayberry tannin-grafted collagen fiber stabilized silver nanoparticles (BT-CF-AgNPs) were characterized by SEM, XRD, TEM, FTIR and XPS. ► BT-CF-AgNPs has the advantages of highly antibacterial activity, good reusability and storage stability.

  12. Antibacterial activity of silver nanoparticles stabilized on tannin-grafted collagen fiber

    Energy Technology Data Exchange (ETDEWEB)

    He Li [National Engineering Laboratory for Clean Technology of Leather Manufacture, Sichuan University, Chengdu 610065 (China); Gao Siying; Wu Hao [Department of Biomass Chemistry and Engineering, Sichuan University, Chengdu 610065 (China); Liao Xuepin, E-mail: xpliao@scu.edu.cn [Department of Biomass Chemistry and Engineering, Sichuan University, Chengdu 610065 (China); He Qiang [National Engineering Laboratory for Clean Technology of Leather Manufacture, Sichuan University, Chengdu 610065 (China); Shi Bi, E-mail: sibitannin@vip.163.com [National Engineering Laboratory for Clean Technology of Leather Manufacture, Sichuan University, Chengdu 610065 (China) and Department of Biomass Chemistry and Engineering, Sichuan University, Chengdu 610065 (China)

    2012-07-01

    Bayberry tannin (BT), a typical plant polyphenol, was grafted on collagen fiber (CF) in different mass ratios. Subsequently, the BT-grafted CF (BT-CF) was used as carrier and stabilizer to prepare BT-CF stabilized silver nanoparticles (BT-CF-AgNPs). Scanning Electron Microscopy image of BT-CF-AgNPs showed that the BT-CF-AgNPs was in ordered fibrous state. X-ray Diffraction patterns and Transmission Electron Microscopy images offered evidence that the Ag nanoparticles were well dispersed on BT-CF. Fourier Transform-Infrared Spectroscopy (FTIR) and X-ray Photoelectron Spectroscopy (XPS) investigations revealed that the Ag NPs were stabilized by the phenolic hydroxyls and quinones of BT on CF through electron donation/acception interaction. Antibacterial experiments demonstrated that BT-CF-AgNPs exhibited high antibacterial activity. When cell suspensions of Escherichia coli and Staphylococcus aureus (10{sup 4}-10{sup 5} cfu/mL) were contacted with BT{sub 0.19}-CF-AgNPs (mass ratio of BT to CF = 0.19, conc. of Ag = 8 {mu}g/mL) at 310 K under constant shaking, the number of cells went down to zero within 2 h. In addition, the minimal inhibitory concentration of BT{sub 0.19}-CF-AgNPs against Escherichia coli, Staphylococcus aureus, Penicillium glaucum and Saccharomyces cerevisiae was 2 {mu}g/mL, 4 {mu}g/mL, 6 {mu}g/mL and 12 {mu}g/mL Ag, respectively. During recycling use, the antibacterial activity of BT{sub 0.19}-CF-AgNPs against Escherichia coli can last for 5 cycles. These facts suggest that BT-CF-AgNPs can be used as a new and effective antibacterial agent. - Highlights: Black-Right-Pointing-Pointer Bayberry tannin-grafted collagen fiber can be acted as carrier and stabilizer for the preparation of nano-silver (AgNPs) with different particle size. Black-Right-Pointing-Pointer Bayberry tannin-grafted collagen fiber stabilized silver nanoparticles (BT-CF-AgNPs) were characterized by SEM, XRD, TEM, FTIR and XPS. Black-Right-Pointing-Pointer BT-CF-AgNPs has the

  13. Surface structural-chemical characterization of a single-site d0 heterogeneous arene hydrogenation catalyst having 100% active sites

    Science.gov (United States)

    Williams, Linda A.; Guo, Neng; Motta, Alessandro; Delferro, Massimiliano; Fragalà, Ignazio L.; Miller, Jeffrey T.; Marks, Tobin J.

    2013-01-01

    Structural characterization of the catalytically significant sites on solid catalyst surfaces is frequently tenuous because their fraction, among all sites, typically is quite low. Here we report the combined application of solid-state 13C-cross-polarization magic angle spinning nuclear magnetic resonance (13C-CPMAS-NMR) spectroscopy, density functional theory (DFT), and Zr X-ray absorption spectroscopy (XAS) to characterize the adsorption products and surface chemistry of the precatalysts (η5-C5H5)2ZrR2 (R = H, CH3) and [η5-C5(CH3)5]Zr(CH3)3 adsorbed on Brønsted superacidic sulfated alumina (AlS). The latter complex is exceptionally active for benzene hydrogenation, with ∼100% of the Zr sites catalytically significant as determined by kinetic poisoning experiments. The 13C-CPMAS-NMR, DFT, and XAS data indicate formation of organozirconium cations having a largely electrostatic [η5-C5(CH3)5]Zr(CH3)2+···AlS− interaction with greatly elongated Zr···OAlS distances of ∼2.35(2) Å. The catalytic benzene hydrogenation cycle is stepwise understandable by DFT, and proceeds via turnover-limiting H2 delivery to surface [η5-C5(CH3)5]ZrH2(benzene)+···AlS− species, observable by solid-state NMR and XAS. PMID:23269836

  14. Poisoning Experiments Aimed at Discriminating Active and Less-Active Sites of Silica-Supported Tantalum Hydride for Alkane Metathesis

    KAUST Repository

    Saggio, Guillaume

    2010-10-04

    Only 50% of the silica-supported tantalum hydride sites are active in the metathesis of propane. Indeed, more than 45% of the tantalum hydride can be eliminated by a selective oxygen poisoning of inactive sites with no significant decrease in the global turnover. Conversely, cyclopentane induces no such selective poisoning. Hence, the active tantalum hydride sites that show greater resistance to oxygen poisoning correspond to the νTa-H bands of higher wavenumbers, particularly that at 1860cm-1. These active tantalum hydride sites should correspond to tris- or monohydride species relatively far from silica surface oxygen atoms. © 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  15. Active Site Loop Dynamics of a Class IIa Fructose 1,6-Bisphosphate Aldolase from Mycobacterium tuberculosis

    Energy Technology Data Exchange (ETDEWEB)

    Pegan, Scott D. [Univ. of Denver, CO (United States); Rukseree, Kamolchanok [National Center for Genetic Engineering and Biotechnology (BIOTEC), Tha Khlong (Thailand); Capodagli, Glenn C. [Univ. of Denver, CO (United States); Baker, Erica A. [Univ. of Denver, CO (United States); Krasnykh, Olga [Univ. of Illinois, Chicago, IL (United States); Franzblau, Scott G. [Univ. of Illinois, Chicago, IL (United States); Mesecar, Andrew D. [Purdue Univ., West Lafayette, IN (United States)

    2013-01-08

    The class II fructose 1,6-bisphosphate aldolases (FBAs, EC 4.1.2.13) comprises one of two families of aldolases. Instead of forming a Schiff base intermediate using an ε-amino group of a lysine side chain, class II FBAs utilize Zn(II) to stabilize a proposed hydroxyenolate intermediate (HEI) in the reversible cleavage of fructose 1,6-bisphosphate, forming glyceraldehyde 3-phosphate and dihydroxyacetone phosphate (DHAP). As class II FBAs have been shown to be essential in pathogenic bacteria, focus has been placed on these enzymes as potential antibacterial targets. Although structural studies of class II FBAs from Mycobacterium tuberculosis (MtFBA), other bacteria, and protozoa have been reported, the structure of the active site loop responsible for catalyzing the protonation–deprotonation steps of the reaction for class II FBAs has not yet been observed. We therefore utilized the potent class II FBA inhibitor phosphoglycolohydroxamate (PGH) as a mimic of the HEI- and DHAP-bound form of the enzyme and determined the X-ray structure of the MtFBA–PGH complex to 1.58 Å. Remarkably, we are able to observe well-defined electron density for the previously elusive active site loop of MtFBA trapped in a catalytically competent orientation. Utilization of this structural information and site-directed mutagenesis and kinetic studies conducted on a series of residues within the active site loop revealed that E169 facilitates a water-mediated deprotonation–protonation step of the MtFBA reaction mechanism. Furthermore, solvent isotope effects on MtFBA and catalytically relevant mutants were used to probe the effect of loop flexibility on catalytic efficiency. Additionally, we also reveal the structure of MtFBA in its holoenzyme form.

  16. Remedial Action Plan and Site Design for Stabilization of the Inactive Uranium Mill Tailings Site, Maybell, Colorado. Remedial action selection report: Attachment 2, Geology report, Final

    Energy Technology Data Exchange (ETDEWEB)

    1994-06-01

    The Maybell uranium mill tailings site is 25 miles (mi) (40 kilometers [km]) west of the town of Craig, Colorado, in Moffat County, in the northwestern part of the state. The unincorporated town of Maybell is 5 road mi (8 km) southwest of the site. The designated site covers approximately 110 acres (ac) (45 hectares [ha]) and consists of a concave-shaped tailings pile and rubble from the demolition of the mill buildings buried in the former mill area. Contaminated materials at the Maybell processing site include the tailings pile, which has an average depth of 20 feet (ft) (6 meters [m]) and contains 2.8 million cubic yards (yd{sup 3}) (2.1 million cubic meters [m{sup 3}]) of tailings. The former mill processing area is on the north side of the site and contains 20,000 yd{sup 3} (15,000 m{sup 3}) of contaminated demolition debris. Off-pile contamination is present and includes areas adjacent to the tailings pile, as well as contamination dispersed by wind and surface water flow. The volume of off-pile contamination to be placed in the disposal cell is 550,000 yd{sup 3} (420,000 m{sup 3}). The total volume of contaminated materials to be disposed of as part of the remedial action is estimated to be 3.37 million yd{sup 3} (2.58 million m{sup 3}). Information presented in this Final Remedial Action Plan (RAP) and referenced in supporting documents represents the current disposal cell design features and ground water compliance strategy proposed by the US Department of Energy (DOE) for the Maybell, Colorado, tailings site. Both the disposal cell design and the ground water compliance strategy have changed from those proposed prior to the preliminary final RAP document as a result of prudent site-specific technical evaluations.

  17. Remedial Action Plan and Site Design for Stabilization of the Inactive Uranium Mill Tailings Site, Maybell, Colorado. Remedial action selection report: Attachment 2, Geology report, Final

    International Nuclear Information System (INIS)

    1994-06-01

    The Maybell uranium mill tailings site is 25 miles (mi) (40 kilometers [km]) west of the town of Craig, Colorado, in Moffat County, in the northwestern part of the state. The unincorporated town of Maybell is 5 road mi (8 km) southwest of the site. The designated site covers approximately 110 acres (ac) (45 hectares [ha]) and consists of a concave-shaped tailings pile and rubble from the demolition of the mill buildings buried in the former mill area. Contaminated materials at the Maybell processing site include the tailings pile, which has an average depth of 20 feet (ft) (6 meters [m]) and contains 2.8 million cubic yards (yd 3 ) (2.1 million cubic meters [m 3 ]) of tailings. The former mill processing area is on the north side of the site and contains 20,000 yd 3 (15,000 m 3 ) of contaminated demolition debris. Off-pile contamination is present and includes areas adjacent to the tailings pile, as well as contamination dispersed by wind and surface water flow. The volume of off-pile contamination to be placed in the disposal cell is 550,000 yd 3 (420,000 m 3 ). The total volume of contaminated materials to be disposed of as part of the remedial action is estimated to be 3.37 million yd 3 (2.58 million m 3 ). Information presented in this Final Remedial Action Plan (RAP) and referenced in supporting documents represents the current disposal cell design features and ground water compliance strategy proposed by the US Department of Energy (DOE) for the Maybell, Colorado, tailings site. Both the disposal cell design and the ground water compliance strategy have changed from those proposed prior to the preliminary final RAP document as a result of prudent site-specific technical evaluations

  18. A universal trend of reduced mRNA stability near the translation-initiation site in prokaryotes and eukaryotes.

    Directory of Open Access Journals (Sweden)

    Wanjun Gu

    2010-02-01

    Full Text Available Recent studies have suggested that the thermodynamic stability of mRNA secondary structure near the start codon can regulate translation efficiency in Escherichia coli, and that translation is more efficient the less stable the secondary structure. We survey the complete genomes of 340 species for signals of reduced mRNA secondary structure near the start codon. Our analysis includes bacteria, archaea, fungi, plants, insects, fishes, birds, and mammals. We find that nearly all species show evidence for reduced mRNA stability near the start codon. The reduction in stability generally increases with increasing genomic GC content. In prokaryotes, the reduction also increases with decreasing optimal growth temperature. Within genomes, there is variation in the stability among genes, and this variation correlates with gene GC content, codon bias, and gene expression level. For birds and mammals, however, we do not find a genome-wide trend of reduced mRNA stability near the start codon. Yet the most GC rich genes in these organisms do show such a signal. We conclude that reduced stability of the mRNA secondary structure near the start codon is a universal feature of all cellular life. We suggest that the origin of this reduction is selection for efficient recognition of the start codon by initiator-tRNA.

  19. Increased amylosucrase activity and specificity, and identification of regions important for activity, specificity and stability through molecular evolution

    DEFF Research Database (Denmark)

    van der Veen, Bart A; Skov, Lars K; Potocki-Véronèse, Gabrielle

    2006-01-01

    , several variants are expected to be improved concerning activity and/or thermostability. Most of the amino acid substitutions observed in the totality of these improved variants are clustered around specific regions. The secondary sucrose-binding site and beta strand 7, connected to the important Asp393...

  20. From phosphatases to vanadium peroxidases: a similar architecture of the active site.

    Science.gov (United States)

    Hemrika, W; Renirie, R; Dekker, H L; Barnett, P; Wever, R

    1997-03-18

    We show here that the amino acid residues contributing to the active sites of the vanadate containing haloperoxidases are conserved within three families of acid phosphatases; this suggests that the active sites of these enzymes are very similar. This is confirmed by activity measurements showing that apochloroperoxidase exhibits phosphatase activity. These observations not only reveal interesting evolutionary relationships between these groups of enzymes but may also have important implications for the research on acid phosphatases, especially glucose-6-phosphatase-the enzyme affected in von Gierke disease-of which the predicted membrane topology may have to be reconsidered.

  1. Wobble pairs of the HDV ribozyme play specific roles in stabilization of active site dynamics

    Czech Academy of Sciences Publication Activity Database

    Sripathi, K.N.; Banáš, P.; Réblová, K.; Šponer, Jiří; Otyepka, M.; Walter, Nils G.

    2015-01-01

    Roč. 17, č. 8 (2015), s. 5887-5900 ISSN 1463-9076 R&D Projects: GA ČR GAP208/12/1878 Institutional support: RVO:68081707 Keywords : HEPATITIS-DELTA-VIRUS * SELF-CLEAVING RIBOZYMES * ACID-BASE CATALYSIS Subject RIV: BO - Biophysics Impact factor: 4.449, year: 2015

  2. A small RNA activates CFA synthase by isoform-specific mRNA stabilization.

    Science.gov (United States)

    Fröhlich, Kathrin Sophie; Papenfort, Kai; Fekete, Agnes; Vogel, Jörg

    2013-11-13

    Small RNAs use a diversity of well-characterized mechanisms to repress mRNAs, but how they activate gene expression at the mRNA level remains not well understood. The predominant activation mechanism of Hfq-associated small RNAs has been translational control whereby base pairing with the target prevents the formation of an intrinsic inhibitory structure in the mRNA and promotes translation initiation. Here, we report a translation-independent mechanism whereby the small RNA RydC selectively activates the longer of two isoforms of cfa mRNA (encoding cyclopropane fatty acid synthase) in Salmonella enterica. Target activation is achieved through seed pairing of the pseudoknot-exposed, conserved 5' end of RydC to an upstream region of the cfa mRNA. The seed pairing stabilizes the messenger, likely by interfering directly with RNase E-mediated decay in the 5' untranslated region. Intriguingly, this mechanism is generic such that the activation is equally achieved by seed pairing of unrelated small RNAs, suggesting that this mechanism may be utilized in the design of RNA-controlled synthetic circuits. Physiologically, RydC is the first small RNA known to regulate membrane stability.

  3. Biomechanical Stability of Dental Implants in Augmented Maxillary Sites: Results of a Randomized Clinical Study with Four Different Biomaterials and PRF and a Biological View on Guided Bone Regeneration

    Science.gov (United States)

    Angelo, Troedhan; Marcel, Wainwright; Andreas, Kurrek; Izabela, Schlichting

    2015-01-01

    Introduction. Bone regenerates mainly by periosteal and endosteal humoral and cellular activity, which is given only little concern in surgical techniques and choice of bone grafts for guided bone regeneration. This study investigates on a clinical level the biomechanical stability of augmented sites in maxillary bone when a new class of moldable, self-hardening calcium-phosphate biomaterials (SHB) is used with and without the addition of Platelet Rich Fibrin (aPRF) in the Piezotome-enhanced subperiosteal tunnel-technique (PeSPTT). Material and Methods. 82 patients with horizontal atrophy of anterior maxillary crest were treated with PeSPTT and randomly assigned biphasic (60% HA/40% bTCP) or monophasic (100% bTCP) SHB without or with addition of aPRF. 109 implants were inserted into the augmented sites after 8.3 months and the insertion-torque-value (ITV) measured as clinical expression of the (bio)mechanical stability of the augmented bone and compared to ITVs of a prior study in sinus lifting. Results. Significant better results of (bio)mechanical stability almost by two-fold, expressed by higher ITVs compared to native bone, were achieved with the used biomaterials and more constant results with the addition of aPRF. Conclusion. The use of SHB alone or combined with aPRF seems to be favourable to achieve a superior (bio)mechanical stable restored alveolar bone. PMID:25954758

  4. Biomechanical Stability of Dental Implants in Augmented Maxillary Sites: Results of a Randomized Clinical Study with Four Different Biomaterials and PRF and a Biological View on Guided Bone Regeneration

    Directory of Open Access Journals (Sweden)

    Troedhan Angelo

    2015-01-01

    Full Text Available Introduction. Bone regenerates mainly by periosteal and endosteal humoral and cellular activity, which is given only little concern in surgical techniques and choice of bone grafts for guided bone regeneration. This study investigates on a clinical level the biomechanical stability of augmented sites in maxillary bone when a new class of moldable, self-hardening calcium-phosphate biomaterials (SHB is used with and without the addition of Platelet Rich Fibrin (aPRF in the Piezotome-enhanced subperiosteal tunnel-technique (PeSPTT. Material and Methods. 82 patients with horizontal atrophy of anterior maxillary crest were treated with PeSPTT and randomly assigned biphasic (60% HA/40% bTCP or monophasic (100% bTCP SHB without or with addition of aPRF. 109 implants were inserted into the augmented sites after 8.3 months and the insertion-torque-value (ITV measured as clinical expression of the (biomechanical stability of the augmented bone and compared to ITVs of a prior study in sinus lifting. Results. Significant better results of (biomechanical stability almost by two-fold, expressed by higher ITVs compared to native bone, were achieved with the used biomaterials and more constant results with the addition of aPRF. Conclusion. The use of SHB alone or combined with aPRF seems to be favourable to achieve a superior (biomechanical stable restored alveolar bone.

  5. Concept for calculating dose rates from activated groundwater at accelerator sites

    CERN Document Server

    Prolingheuer, N; Vanderborght, J; Schlögl, B; Nabbi, R; Moormann, R

    Licensing of particle accelerators requires the proof that the groundwater outside of the site will not be significantly contaminated by activation products formed below accelerator and target. In order to reduce the effort for this proof, a site independent simplified but conservative method is under development. The conventional approach for calculation of activation of soil and groundwater is shortly described on example of a site close to Forschungszentrum Juelich, Germany. Additionally an updated overview of a data library for partition coefficients for relevant nuclides transported in the aquifer at the site is presented. The approximate model for transport of nuclides with ground water including exemplary results on nuclide concentrations outside of the site boundary and of resulting effective doses is described. Further applications and developments are finally outlined.

  6. Stability and Antioxidant Activity of Semi-synthetic Derivatives of 4-Nerolidylcatechol

    Directory of Open Access Journals (Sweden)

    Emerson Silva Lima

    2012-12-01

    Full Text Available 4-nerolidylcatechol (4-NC is an unstable natural product that exhibits important antioxidant, anti-inflammatory and other properties. It is readily obtainable on a multi-gram scale through straightforward solvent extraction of the roots of cultivated Piper peltatum or P. umbellatum, followed by column chromatography on the resulting extract. Semi-synthetic derivatives of 4-NC with one or two substituent groups (methyl, acetyl, benzyl, benzoyl on the O atoms have been introduced that have increased stability compared to 4-NC and significant in vitro inhibitory activity against the human malaria parasite Plasmodium falciparum. Antioxidant and anti-inflammatory properties may be important for the antiplasmodial mode of action of 4-NC derivatives. Thus, we decided to investigate the antioxidant properties, cytotoxicity and stability of 4-NC derivatives as a means to explore the potential utility of these compounds. 4-NC showed high antioxidant activity in the DPPH and ABTS assays and in 3T3-L1 cells (mouse embryonic fibroblast, however 4-NC was more cytotoxic (IC50 = 31.4 µM and more unstable than its derivatives and lost more than 80% of its antioxidant activity upon storage in solution at −20 °C for 30 days. DMSO solutions of mono-O-substituted derivatives of 4-NC exhibited antioxidant activity and radical scavenging activity in the DPPH and ABTS assays that was comparable to that of BHA and BHT. In the cell-based antioxidant model, most DMSO solutions of derivatives of 4-NC were less active on day 1 than 4-NC, quercetin and BHA and more active antioxidants than BHT. After storage for 30 days at −20 °C, DMSO solutions of most of the derivatives of 4-NC were more stable and exhibited more antioxidant activity than 4-NC, quercetin and BHA and exhibited comparable antioxidant activity to BHT. These findings point to the potential of derivatives of 4-NC as antioxidant compounds.

  7. Heat shock modulates the subcellular localization, stability, and activity of HIPK2

    Energy Technology Data Exchange (ETDEWEB)

    Upadhyay, Mamta; Bhadauriya, Pratibha; Ganesh, Subramaniam, E-mail: sganesh@iitk.ac.in

    2016-04-15

    The homeodomain-interacting protein kinase-2 (HIPK2) is a highly conserved serine/threonine kinase and is involved in transcriptional regulation. HIPK2 is a highly unstable protein, and is kept at a low level under normal physiological conditions. However, exposure of cells to physiological stress – such as hypoxia, oxidative stress, or UV damage – is known to stabilize HIPK2, leading to the HIPK2-dependent activation of p53 and the cell death pathway. Therefore HIPK2 is also known as a stress kinase and as a stress-activated pro-apoptotic factor. We demonstrate here that exposure of cells to heat shock results in the stabilization of HIPK2 and the stabilization is mediated via K63-linked ubiquitination. Intriguingly, a sub-lethal heat shock (42 °C, 1 h) results in the cytoplasmic localization of HIPK2, while a lethal heat shock (45 °C, 1 h) results in its nuclear localization. Cells exposed to the lethal heat shock showed significantly higher levels of the p53 activity than those exposed to the sub-lethal thermal stress, suggesting that both the level and the nuclear localization are essential for the pro-apoptotic activity of HIPK2 and that the lethal heat shock could retain the HIPK2 in the nucleus to promote the cell death. Taken together our study underscores the importance of HIPK2 in stress mediated cell death, and that the HIPK2 is a generic stress kinase that gets activated by diverse set of physiological stressors.

  8. Heat shock modulates the subcellular localization, stability, and activity of HIPK2

    International Nuclear Information System (INIS)

    Upadhyay, Mamta; Bhadauriya, Pratibha; Ganesh, Subramaniam

    2016-01-01

    The homeodomain-interacting protein kinase-2 (HIPK2) is a highly conserved serine/threonine kinase and is involved in transcriptional regulation. HIPK2 is a highly unstable protein, and is kept at a low level under normal physiological conditions. However, exposure of cells to physiological stress – such as hypoxia, oxidative stress, or UV damage – is known to stabilize HIPK2, leading to the HIPK2-dependent activation of p53 and the cell death pathway. Therefore HIPK2 is also known as a stress kinase and as a stress-activated pro-apoptotic factor. We demonstrate here that exposure of cells to heat shock results in the stabilization of HIPK2 and the stabilization is mediated via K63-linked ubiquitination. Intriguingly, a sub-lethal heat shock (42 °C, 1 h) results in the cytoplasmic localization of HIPK2, while a lethal heat shock (45 °C, 1 h) results in its nuclear localization. Cells exposed to the lethal heat shock showed significantly higher levels of the p53 activity than those exposed to the sub-lethal thermal stress, suggesting that both the level and the nuclear localization are essential for the pro-apoptotic activity of HIPK2 and that the lethal heat shock could retain the HIPK2 in the nucleus to promote the cell death. Taken together our study underscores the importance of HIPK2 in stress mediated cell death, and that the HIPK2 is a generic stress kinase that gets activated by diverse set of physiological stressors.

  9. Adaptive neural networks control for camera stabilization with active suspension system

    Directory of Open Access Journals (Sweden)

    Feng Zhao

    2015-08-01

    Full Text Available The camera always suffers from image instability on the moving vehicle due to unintentional vibrations caused by road roughness. This article presents an adaptive neural network approach mixed with linear quadratic regulator control for a quarter-car active suspension system to stabilize the image captured area of the camera. An active suspension system provides extra force through the actuator which allows it to suppress vertical vibration of sprung mass. First, to deal with the road disturbance and the system uncertainties, radial basis function neural network is proposed to construct the map between the state error and the compensation component, which can correct the optimal state-feedback control law. The weights matrix of radial basis function neural network is adaptively tuned online. Then, the closed-loop stability and asymptotic convergence performance is guaranteed by Lyapunov analysis. Finally, the simulation results demonstrate that the proposed controller effectively suppresses the vibration of the camera and enhances the stabilization of the entire camera, where different excitations are considered to validate the system performance.

  10. Expression, purification and characterization of a novel double-sites mutant of the single-chain sweet-tasting protein monellin (MNEI) with both improved sweetness and stability.

    Science.gov (United States)

    Zheng, Weiwei; Yang, Liu; Cai, Chenggu; Ni, Jinfeng; Liu, Bo

    2018-03-01

    The sweet protein monellin has high sweet potency with limited stability. In this study, 3 double-sites mutants (E2N/E23A, E2N/Y65R and E23A/Y65R) of the single-chain monellin (MNEI) were constructed. The proteins were expressed in E. coli BL21 and purified to homogeneity by nickel affinity chromatography with yields above 10 mg/L cell culture. Introduction of a sweeter mutant E2N into E23A or Y65R (E2N/E23A and E2N/Y65R) led to about 3-fold increase of sweetness, while addition of a more stable mutant E23A into E2N or Y65R (E2N/E23A and E23A/Y65R) resulted in improved thermal stability (about 10 °C). The results indicate that residues E2 and E23 mediate the sweetness and thermal stability of the protein, respectively. Multiple mutations of different residues (E2N/E23A) led to an additive performance with both improved sweetness and stability, suggesting that the sweetness and stability could be modulated by the independent molecular mechanism. The sweeter and thermal stable variant has a potential in further industrial applications. Copyright © 2017 Elsevier Inc. All rights reserved.

  11. Determination of the protease cleavage site repertoire—The RNase H but not the RT domain is essential for foamy viral protease activity

    Energy Technology Data Exchange (ETDEWEB)

    Spannaus, Ralf; Bodem, Jochen, E-mail: Jochen.Bodem@vim.uni-wuerzburg.de

    2014-04-15

    In contrast to orthoretroviruses, the foamy virus protease is only active as a protease-reverse transcriptase fusion protein and requires viral RNA for activation. Maturation of foamy viral proteins seems to be restricted to a single cleavage site in Gag and Pol. We provide evidence that unprocessed Gag is required for optimal infectivity, which is unique among retroviruses. Analyses of the cleavage site sequences of the Gag and Pol cleavage sites revealed a high similarity compared to those of Lentiviruses. We show that positions P2' and P2 are invariant and that Gag and Pol cleavage sites are processed with similar efficiencies. The RNase H domain is essential for protease activity, but can functionally be substituted by RNase H domains of other retroviruses. Thus, the RNase H domain might be involved in the stabilization of the protease dimer, while the RT domain is essential for RNA dependent protease activation. - Highlights: • Unprocessed Gag is required for optimal infectivity of foamy viruses. • Positions P2 and P2' are invariant in the foamy viral cleavage sites. • The RNaseH domain is essential for protease activity. • The RNaseH domains of other retroviruses support foamy viral protease activity.

  12. Determination of the protease cleavage site repertoire—The RNase H but not the RT domain is essential for foamy viral protease activity

    International Nuclear Information System (INIS)

    Spannaus, Ralf; Bodem, Jochen

    2014-01-01

    In contrast to orthoretroviruses, the foamy virus protease is only active as a protease-reverse transcriptase fusion protein and requires viral RNA for activation. Maturation of foamy viral proteins seems to be restricted to a single cleavage site in Gag and Pol. We provide evidence that unprocessed Gag is required for optimal infectivity, which is unique among retroviruses. Analyses of the cleavage site sequences of the Gag and Pol cleavage sites revealed a high similarity compared to those of Lentiviruses. We show that positions P2' and P2 are invariant and that Gag and Pol cleavage sites are processed with similar efficiencies. The RNase H domain is essential for protease activity, but can functionally be substituted by RNase H domains of other retroviruses. Thus, the RNase H domain might be involved in the stabilization of the protease dimer, while the RT domain is essential for RNA dependent protease activation. - Highlights: • Unprocessed Gag is required for optimal infectivity of foamy viruses. • Positions P2 and P2' are invariant in the foamy viral cleavage sites. • The RNaseH domain is essential for protease activity. • The RNaseH domains of other retroviruses support foamy viral protease activity

  13. Demonstration of In-Situ Stabilization of Buried Waste at Pit G-11 at the Brookhaven National laboratory Glass Pits Disposal Site

    International Nuclear Information System (INIS)

    Dwyer, B.P.; Gilbert, J.; Heiser, J.

    1999-01-01

    In 1989 BNL was added to the EPAs National Priorities List. The site is divided into seven operable units (OU). OU-I includes the former landfill area. The field task site is noted as the AOC 2C Glass Holes location. Beginning in the 1960s and continuing into the 1980s, BNL disposed of laboratory waste (glassware, chemicals and animal carcasses) in numerous shallow pits. The drivers for remediating the pits are; historical records that indicate hazardous materials may have been disposed of in the pits; ground water contamination down gradient of the pits; a test excavation of one of the glass holes that unearthed laboratory glass bottles with unidentified liquids still contained; and the fact that BNL rests atop an EPA designated sole-source aquifer. The specific site chosen for this demonstration was pit G-11. The requirements that lead to choosing this pit were; a well characterized pit and a relatively isolated pit where our construction operations would not impact on adjacent pits. The glass holes area, including pit G-11, was comprehensively surveyed using a suite of geophysical techniques (e.g., EM-31, EM-61, GPR). Prior to stabilizing the waste form a subsurface barrier was constructed to contain the entire waste pit. The pit contents were then stabilized using a cement grout applied via jet grouting. The stabilization was performed to make removal of the waste from the pit easier and safer in terms of worker exposure. The grouting process would mix and masticate the waste and grout and form a single monolithic waste form. This large monolith would then be subdivided into smaller 4 foot by 4 foot by 10-12 foot block using a demolition grout. The smaller blocks would then be easily removed from the site and disposed of in a CERCLA waste site

  14. Computational evaluations of charge coupling and hydrogen bonding in the active site of a family 7 cellobiohydrolase.

    Science.gov (United States)

    Granum, David M; Vyas, Shubham; Sambasivarao, Somisetti V; Maupin, C Mark

    2014-01-16

    Solution pH and the pKa values of ionizable residues are critical factors known to influence enzyme catalysis, structural stability, and dynamical fluctuations. Presented here is an exhaustive computational study utilizing long time constant pH molecular dynamics, pH replica exchange simulations, and kinetic modeling to evaluate pH-dependent conformations, charge dynamics, residue pKa values, and the catalytic activity-pH profile for cellobiohydrolase Cel7B from Melanocarpus albomyces . The predicted pKa values support the role of Glu212 as the catalytic nucleophile and Glu217 as the acid-base residue. The presence of a charge-correlated active site and an extensive hydrogen bonding network is found to be critical in enabling favorable residue orientations for catalysis and shuttling excess protons around the active site. Clusters of amino acids are identified that act in concert to effectively modulate the optimal pH for catalysis while elevating the overall catalytic rate with respect to a noncoupled system. The work presented here demonstrates the complex and critical role of coupled ionizable residues to the proper functioning of cellobiohydrolase Cel7B, functionally related glycosyl hydrolases, and enzymes in general. The simulations also support the use of the CpHMD for the accurate prediction of residue pKa values and to evaluate the impact of pH on protein structure and charge dynamics.

  15. Polyphenolic content, antiradical activity, stability and microbiological quality of elderberry (Sambucus nigra L.) extracts.

    Science.gov (United States)

    Pliszka, Barbara

    2017-01-01

    The pharmaceutical and food industries expect detailed knowledge on the physicochemical properties of elderberry fruit extracts, their stability and microbiological quality, as well as the polyphenol content in elderberry cultivars. The characteristics of the extracts might be additionally modified by citric acid, which improves the stability of anthocyanins and protects processed fruits and syrups from pathogenic microorganisms. The choice of the method with citric acid was a consequence of the physicochemical charac teristics of elderberry pigments, which are not stable under the effect of light in alcoholic solutions. The aim of study was to analyze the properties of elderberry fruit extracts regarding polyphenol content and antiradical activity, as well as their stability and microbiological quality. The plant material consisted of fruit from four cultivars (Alleso, Korsor, Sampo, Samyl) of black elderberry (Sambucus nigra L.). The following were determined in fruit extracts: polyphe- nolic content (HPLC), antiradical activity (ABTS and DPPH) and stability and microbiological quality. The HPLC analysis of polyphenols demonstrated that the extracts from fruits collected from cv. Samyl had the highest 3-sambubioside cyanidin content and those from cv. Korsor contained the highest quantity of 3-glucoside cyanidin. The extracts from cv. Sampo fruit had a dominant 3-sambubioside-5-gluco- side cyanidin and 3,5-diglucoside cyanidin content. The highest quercetin (5.92 mg 100 mg-1 of extract) and caffeic acid (1.21 mg 100 mg-1 of extract) content was found in fruit extracts from cv. Alleso. The cultivars Samyl and Korsor had a higher level of anthocyanins and higher antiradical activity (ABTS) in fruit extracts than cv. Alleso and Sampo. The antiradical activity (DPPH) of fruit extracts from elderberry cultivars as- sessed in this research was similar. The degradation index for all fruit extracts was similar (DI = 1.035). The microbiological species detected in

  16. Harmonic Active Filtering and Impedance-based Stability Analysis in Offshore Wind Power Plants

    DEFF Research Database (Denmark)

    Dhua, Debasish; Yang, Guangya; Zhang, Zhe

    2017-01-01

    Nowadays, to eliminate harmonics injected by the wind turbines in offshore wind power plants there is a need to install passive filters. Moreover, the passive filters are not adaptive to harmonic profile changes due to topology changes, grid loading etc. Therefore, active filters in wind turbines...... installation and provides effectively similar functionality as passive filters. This work is focused on harmonic propagation studies in wind power plants, power quality evaluation at the point of connection and harmonic mitigation by active filtering. Finally, an impedance-based stability analysis...... are proposed as a flexible harmonic mitigation measure. The motivation of this study is to explore the possibility of embedding active filtering in wind turbine grid-side converters without having to change the system electrical infrastructure. The active filtering method can prevent additional equipment...

  17. Stability Analysis and Active Damping for LLCL-filter-Based Grid-Connected Inverters

    DEFF Research Database (Denmark)

    Huang, Min; Wang, Xiongfei; Loh, Poh Chiang

    2015-01-01

    A higher-order passive power filter (LLCL-filter) for the grid-connected inverter is becoming attractive for the industrial applications due to the possibility to reduce the cost of the copper and the magnetic material. To avoid the well-known resonance problems of the LLCL-filter, it is requested...... to use either passive or active damping methods. This paper analyzes the stability of the LLCL-filter based grid-connected inverter and identifies a critical resonant frequency for the LLCL-filter when sampling and transport delays are considered. In a high resonant frequency region the active damping...... is not required but in a low resonant frequency region the active damping is necessary. The basic LLCL resonance damping properties of different feedback states based on a notch filter concept are also studied. Then an active damping method which is using the capacitor current feedback for LLCL-filter...

  18. The status of siting activities for a low level waste repository in the Philippines

    International Nuclear Information System (INIS)

    Valdezco, E.M.; Visitacion, M.; Palattao, B.; Marcelo, E.A.; Venida, L.L.

    2001-01-01

    The process of site selection for a low level waste repository was initiated in 1976 when the Philippine Government decided to go nuclear and constructed the first Philippine Nuclear Power Plant in the Bataan Peninsula. However, all siting activities were suspended when the nuclear power plant was mothballed and the final decision was made to convert the plant into a combined cycle power plant. In 1995, an inter-agency committee was created under the Nuclear Power Steering Committee and mandated to conduct studies on siting of radioactive waste disposal facilities, and at the same time, perform R and D activities in support of the project. This paper describes the various siting activities carried out to date. (author)

  19. Frequency domain stability analysis of nonlinear active disturbance rejection control system.

    Science.gov (United States)

    Li, Jie; Qi, Xiaohui; Xia, Yuanqing; Pu, Fan; Chang, Kai

    2015-05-01

    This paper applies three methods (i.e., root locus analysis, describing function method and extended circle criterion) to approach the frequency domain stability analysis of the fast tool servo system using nonlinear active disturbance rejection control (ADRC) algorithm. Root locus qualitative analysis shows that limit cycle is generated because the gain of the nonlinear function used in ADRC varies with its input. The parameters in the nonlinear function are adjustable to suppress limit cycle. In the process of root locus analysis, the nonlinear function is transformed based on the concept of equivalent gain. Then, frequency domain description of the nonlinear function via describing function is presented and limit cycle quantitative analysis including estimating prediction error is presented, which virtually and theoretically demonstrates that the describing function method cannot guarantee enough precision in this case. Furthermore, absolute stability analysis based on extended circle criterion is investigated as a complement. Copyright © 2014 ISA. Published by Elsevier Ltd. All rights reserved.

  20. Activity and stability studies of platinized multi-walled carbon nanotubes as fuel cell electrocatalysts

    DEFF Research Database (Denmark)

    Stamatin, Serban Nicolae; Borghei, Maryam; Dhiman, Rajnish

    2015-01-01

    A non-covalent functionalization for multi-walled carbon nanotubes has been used as an alternative to the damaging acid treatment. Platinum nanoparticles with similar particle size distribution have been deposited on the surface modified multi-walled carbon nanotubes. The interaction between...... platinum nanoparticles and multi-walled carbon nanotubes functionalized with 1-pyrenecarboxylic acid is studied and its electrochemical stability investigated. This study reveals the existence of a platinum-support interaction and leads to three main conclusions. First, the addition of 1-pyrenecarboxylic...... acid is improving the dispersion of platinum nanoparticles, leading to an improved electrochemical activity towards oxygen reduction reaction. Second, the investigations regarding the electrochemical stability showed that the platinum-support interaction plays an important role in improving the long...