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Sample records for chain transfer agents

  1. Chain termination in polyhydroxyalkanoate synthesis: involvement of exogenous hydroxy-compounds as chain transfer agents.

    PubMed

    Madden, L A; Anderson, A J; Shah, D T; Asrar, J

    1999-01-01

    We have identified a range of compounds which, when present during poly(3-hydroxybutyrate) [P(3HB)] accumulation by Ralstonia eutropha (reclassified from Alcaligenes eutrophus), can act as chain transfer agents in the chain termination step of polymerization. End-group analysis by 31P NMR of polymer derivatized with 2-chloro-4,4,5,5-tetramethyl-1,3,2-dioxaphospholane revealed that all these compounds were covalently linked to P(3HB) at the carboxyl terminus. All chain transfer agents possessed one or more hydroxyl groups, and glycerol was selected for further investigation. The number-average molecular mass (Mn) of P(3HB) produced by R. eutropha from glycerol was substantially lower than for polymer produced from glucose, and we identified two new end-group structures. These were attributed to a glycerol molecule bound to the P(3HB) chain via the primary or secondary hydroxyl groups. When a primary hydroxyl group of glycerol is involved in chain transfer, the end-group structure is in both [R] and [S] configurations, implying that chain transfer to glycerol is a random transesterification and that PHA synthase does not catalyse chain transfer. 3-Hydroxybutyric acid is the most probable chain transfer agent in vivo, with propagation and termination reactions involving transfer of the P(3HB) chain to enzyme-bound and free 3-hydroxybutyrate, respectively. Only carboxyl end-groups were detected in P(3HB) extracted from exponentially growing bacteria. It is proposed that a compound other than 3-hydroxybutyryl-CoA acts as a primer in the initiation of polymer synthesis. PMID:10416649

  2. Volume holographic recording in nanoparticle-polymer composites doped with multifunctional chain transfer agents

    NASA Astrophysics Data System (ADS)

    Guo, Jinxin; Fujii, Ryuta; Tomita, Yasuo

    2015-10-01

    We report on an experimental investigation of the properties of volume holographic recording in photopolymerizable nanoparticle-polymer composites (NPCs) doped with chain transferring multifunctional di- and tri-thiols as chain transfer agents. It is shown that the incorporation of the multifunctional thiols into NPCs more strongly influences on volume holographic recording than that doped with mono-thiol since more chemical reactions involve in the polymer network formation. It is found that, as similar to the case of mono-thiol doping, there exist optimum concentrations of di- and tri-thiols for maximizing the saturated refractive index modulation. It is also seen that recording sensitivity monotonically decreases with an increase in multifunctional thiol concentration due to the partial inhibition of the photopolymerization event by excessive thiols.

  3. Z-Group ketone chain transfer agents for RAFT polymer nanoparticle modification via hydrazone conjugation

    PubMed Central

    Bandyopadhyay, Saibal; Xia, Xin; Maiseiyeu, Andrei; Mihai, Georgeta; Rajagopalan, Sanjay

    2012-01-01

    A ketal-containing trithiocarbonyl compound has been synthesized and characterized as a chain transfer agent (CTA) in Reversible Addition Fragmentation Transfer (RAFT) polymerization. The ketal functionality does not interfere with RAFT polymerization of acrylate monomers, which proceeds as previously reported to yield macro-CTA polymers and block co-polymers. Post-polymerization ketal cleavage revealed ketone functionality at the polar terminus of an amphiphilic block co-polymer. Hydrazone-formation was facile in both organic solution as well as in aqueous buffer where polymer nanoparticle assemblies were formed, indicating a conjugation/end-functionalization yield of 40–50%. Conjugation was verified with fluorescein, biotin and Gd-DOTA derivatives, and though the trithiocarbonate linkage is hydrolytically labile, we observed stable conjugation for several days at pH 7.4. and 37°C. As expected, streptavidin binding to biotinylated polymer micelles was observed, and size-change based relaxivity increases were observed when Gd-DOTA hydrazide was conjugated to polymer micelles. Cell-uptake of fluorescently labeled polymer micelles was also readily tracked by FACS and fluorescence microscopy. These polymer derivatives demonstrate a range of potential theranostic/biotechnological applications for this conveniently accessible keto-CTA, which include ligand-based nanoparticle targeting and fluorescent/MR nanoparticle contrast agents. PMID:23148126

  4. Facile Fabrication of Water Dispersible Latex Particles with Homogeneous or Chain-Segregated Surface from RAFT Polymerization Using a Mixture of Two Macromolecular Chain Transfer Agents.

    PubMed

    Sun, Li; Hong, Liangzhi; Wang, Chaoyang

    2016-04-01

    Water dispersible latex particles with randomly mixed shells or chain segregated surface are synthesized from one-pot reversible addition-fragmentation chain transfer heterogeneous polymerization of benzyl methacrylate (BzMA) using a mixture of poly(glycerol monomethacrylate) (PGMA) and poly(2,3-bis(succinyloxy)propyl methacrylate) (PBSPMA) macromolecular chain transfer agents. In methanol, the two in situ synthesized PGMA-b-PBzMA and PBSPMA-b-PBzMA diblock copolymers coaggregate into spherical micelles, which contain PBzMA core and discrete PGMA and PBSPMA nanodomains on the shell. In contrast, in water-methanol mixture (V/V = 9/1), latex particles with homogeneous distribution of PGMA and PBSPMA polymer chains on the shell are obtained. The reasons leading to formation of latex particles with homogenous or chain-segregated surface are discussed, and polymerization kinetics and physical state of PBSPMA in methanol and water-methanol mixtures are ascribed. These polymeric micelles with patterned functional group on the surface are potentially important for application in supracolloidal hierarchical assemblies and catalysis. PMID:26954075

  5. Spatial frequency response of a volume hologram recorded in a ZrO2 nanoparticle-dispersed acrylate photopolymer film containing chain transfer agents

    NASA Astrophysics Data System (ADS)

    Guo, Jinxin; Fujii, Ryuta; Tomita, Yasuo

    2014-05-01

    Photopolymerizable nanoparticle-polymer composites (NPCs) have thus far shown their excellent performance in various applications, such as holographic data storage, nonlinear optics and neutron optics. Specifically, for such applications, a high spatial frequency material response is necessary, as it is the response to high spatial frequencies that determines their spatial resolution and diffraction properties. However, it is known that the spatial frequency response of a recorded hologram in multi-component photopolymers including NPCs and holographic polymer-dispersed liquid crystals exhibits a reduction in refractive index modulation at high spatial frequencies. In order to overcome this drawback, an addition of chain transfer agents (CTAs) may be useful as done for all-organic photopolymers to modify their nonlocal response and phase separation characteristics. In our work, we investigate the effect of CTAs on the spatial frequency response in NPCs. Here we employ various chain-transfer agents with three different thiol groups in a photopolymerizable ZrO2 NPC film. A range of CTA concentration is carried out, in order to explore the most effective material combination used in the examination of spatial frequency response. The significant improvement in spatial frequency response of NPCs through the addition of a CTA with the most appropriate concentration is presented.

  6. Reversible addition-fragmentation chain transfer polymerization in microemulsion.

    PubMed

    O'Donnell, Jennifer M

    2012-04-21

    This tutorial review first details the uncontrolled microemulsion polymerization mechanism, and the RAFT polymerization mechanism to provide the necessary background for examining the RAFT microemulsion polymerization mechanism. The effect of the chain transfer agent per micelle ratio and the chain transfer agent aqueous solubility on the RAFT microemulsion polymerization kinetics, polymer molecular weight and polydispersity, and polymer nanoparticle size are discussed with a focus on oil-in-water microemulsions. Modeling of RAFT microemulsion polymerization kinetics and the resulting final polymer molecular weight are presented to assist with the analysis of observed experimental trends. Lastly, the current significance of RAFT microemulsion polymerization and the future directions are discussed. PMID:22246214

  7. Excitation transfer in stacked quantum dot chains

    NASA Astrophysics Data System (ADS)

    Kanjanachuchai, Songphol; Xu, Ming; Jaffré, Alexandre; Jittrong, Apichart; Chokamnuai, Thitipong; Panyakeow, Somsak; Boutchich, Mohamed

    2015-05-01

    Stacked InAs quantum dot chains (QDCs) on InGaAs/GaAs cross-hatch pattern (CHP) templates yield a rich emission spectrum with an unusual carrier transfer characteristic compared to conventional quantum dot (QD) stacks. The photoluminescent spectra of the controlled, single QDC layer comprise multiple peaks from the orthogonal QDCs, the free-standing QDs, the CHP, the wetting layers and the GaAs substrate. When the QDC layers are stacked, employing a 10 nm GaAs spacer between adjacent QDC layers, the PL spectra are dominated by the top-most stack, indicating that the QDC layers are nominally uncoupled. Under high excitation power densities when the high-energy peaks of the top stack are saturated, however, low-energy PL peaks from the bottom stacks emerge as a result of carrier transfers across the GaAs spacers. These unique PL signatures contrast with the state-filling effects in conventional, coupled QD stacks and serve as a means to quickly assess the presence of electronic coupling in stacks of dissimilar-sized nanostructures.

  8. 12 CFR 341.3 - Registration as securities transfer agent.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 12 Banks and Banking 4 2010-01-01 2010-01-01 false Registration as securities transfer agent. 341... OF GENERAL POLICY REGISTRATION OF SECURITIES TRANSFER AGENTS § 341.3 Registration as securities... functions of a transfer agent as described in § 341.2(a) with respect to qualifying securities...

  9. 12 CFR 341.3 - Registration as securities transfer agent.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 12 Banks and Banking 5 2012-01-01 2012-01-01 false Registration as securities transfer agent. 341... OF GENERAL POLICY REGISTRATION OF SECURITIES TRANSFER AGENTS § 341.3 Registration as securities... functions of a transfer agent as described in § 341.2(a) with respect to qualifying securities...

  10. 12 CFR 341.3 - Registration as securities transfer agent.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 12 Banks and Banking 4 2011-01-01 2011-01-01 false Registration as securities transfer agent. 341... OF GENERAL POLICY REGISTRATION OF SECURITIES TRANSFER AGENTS § 341.3 Registration as securities... functions of a transfer agent as described in § 341.2(a) with respect to qualifying securities...

  11. Transfer of Select Agents and Toxins: 2003-2013.

    PubMed

    Shelby, Bryan D; Cartagena, Debora; McClee, Vondguraus; Gangadharan, Denise; Weyant, Robbin

    2015-01-01

    The Federal Select Agent Program, which is composed of the Centers for Disease Control and Prevention Division of Select Agents and Toxins and the Animal and Plant Health Inspection Service Agricultural Select Agent Services, regulates entities that possess, use, or transfer biological select agents and toxins in the United States and must preapprove all transfers within or into the US. The requirement to preapprove transfers allows the Federal Select Agent Program to monitor and track shipments to receive alerts of theft, loss, or release during shipment, thereby protecting public health and safety. As part of the program, the Division of Select Agents and Toxins regulates biological select agents and toxins that have been identified by the US government as posing a severe threat to public health and safety. The division analyzed 4,402 transfers that occurred between March 2003 and December 2013 to identify frequently transferred biological select agents and toxins and the types of entities involved in transfers. During the study period, 1 package was lost during shipment and it was determined not to pose a threat to public health. The Federal Bureau of Investigation investigated the loss and concluded that the package was most likely damaged by the commercial carrier and discarded. Further, there were no reports of theft or release associated with biological select agents and toxins shipments. This report represents the first in-depth review of biological select agent and toxin transfers that were approved by the Division of Select Agents and Toxins. PMID:26186667

  12. Effect of perturbations on information transfer in spin chains

    SciTech Connect

    Ronke, R.; D'Amico, I.; Spiller, T. P.

    2011-01-15

    Spin chains have been proposed as a reliable and convenient way of transferring information and entanglement in a quantum computational context. Nonetheless, it has to be expected that any physical implementation of these systems will be subject to several perturbative factors which could potentially diminish the transfer quality. In this paper, we investigate a number of possible fabrication defects in the spin chains themselves as well as the effect of nonsynchronous or imperfect input operations, with a focus on the case of multiple excitation and qubit transfer. We consider both entangled and unentangled states and, in particular, the transfer of an entangled pair of adjacent spins at one end of a chain under the mirroring rule and also the creation of entanglement resulting from injection at both end spins.

  13. Chain Transfer of Vegetable Oil Macromonomers in Acrylic Solution Copolymerization

    SciTech Connect

    Black, Micah; Messman, Jamie M; Rawlins, James

    2011-01-01

    Use of vegetable oil macromonomers (VOMMs) as comonomers in emulsion polymerization enables good film coalescence without the addition of solvents that constitute volatile organic compounds (VOCs). VOMMs are derived from renewable resources and offer the potential of post-application crosslinking via auto-oxidation. However, chain transfer reactions of VOMMs with initiator and/or polymer radicals during emulsion polymerization reduce the amount of allylic hydrogen atoms available for primary auto-oxidation during drying. Vegetable oils and derivatives were reacted in combination with butyl acrylate and methyl methacrylate via solution polymerization. The copolymerization was monitored using in situ infrared spectroscopy to determine the extent of chain transfer. 1H NMR spectroscopy was used to determine the loci of chain transfer and the molecular weight characteristics of the polymers were characterized by SEC. Solution polymerization was utilized to minimize temperature fluctuations and maintain polymer solubility during the initial characterization.

  14. 76 FR 16843 - Order Cancelling Registrations of Certain Transfer Agents

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-03-25

    ....C. 78q-1(c)(4)(B). \\2\\ Securities Exchange Act Release No. 63211 (Oct. 29, 2010), 75 FR 68012. For... Services) 8405926 GTI Corporate Transfer Agents LLC 8406151 Guarantee Services CORP 8406145 HOLA...

  15. Chain elongation analog of resveratrol as potent cancer chemoprevention agent.

    PubMed

    Kang, Yan-Fei; Qiao, Hai-Xia; Xin, Long-Zuo; Ge, Li-Ping

    2016-09-01

    Resveratrol is identified as a natural cancer chemoprevention agent. There has been a lot of interest in designing and developing resveratrol analogs with cancer chemoprevention activity superior to that of parent molecule and exploring their action mechanism in the past several decades. In this study, we have synthesized resveratrol analogs of compounds A-C via conjugated chain elongation based on isoprene unit retention strategy. Remarkably, cytotoxic activity analysis results indicated that compound B possesses the best proliferation inhibition activity for NCI-H460 cells in all the test compounds. Intriguingly, compound B displayed a higher cytotoxicity against human non-small cell lung cancer cells (NCI-H460) compared to normal human embryonic lung fibroblasts (MRC-5). Afterward, flow cytometry analysis showed that compound B would induce cell apoptosis. We further researched the action mechanism. When NCI-H460 cells were incubated by compound B for 6 or 9 h, respectively, the intracellular reactive oxygen species (ROS) level was enhanced obviously. With elevation of intracellular ROS level, flow cytometry measurement verified mitochondrial transmembrane potential collapse, which was accompanied by the up-regulation of Bax and down-regulation of Bcl-2. More interestingly, compound B increased the expression of caspase-9 and caspase-3, which induced cell apoptosis. Moreover, compound B arrested cell cycle in G0/G1 phase. These are all to provide useful information for designing resveratrol-based chemoprevention agent and understanding the action mechanism. PMID:27160168

  16. State of research: environmental pathways and food chain transfer.

    PubMed Central

    Vaughan, B E

    1984-01-01

    Data on the chemistry of biologically active components of petroleum, synthetic fuel oils, certain metal elements and pesticides provide valuable generic information needed for predicting the long-term fate of buried waste constituents and their likelihood of entering food chains. Components of such complex mixtures partition between solid and solution phases, influencing their mobility, volatility and susceptibility to microbial transformation. Estimating health hazards from indirect exposures to organic chemicals involves an ecosystem's approach to understanding the unique behavior of complex mixtures. Metabolism by microbial organisms fundamentally alters these complex mixtures as they move through food chains. Pathway modeling of organic chemicals must consider the nature and magnitude of food chain transfers to predict biological risk where metabolites may become more toxic than the parent compound. To obtain predictions, major areas are identified where data acquisition is essential to extend our radiological modeling experience to the field of organic chemical contamination. PMID:6428875

  17. Optimization of excitation transfer in a spin chain

    NASA Astrophysics Data System (ADS)

    Gurman, Vladimir I.; Guseva, Irina S.; Fesko, Oles V.

    2016-06-01

    A revised formulation of the problem of fastest transfer of the excitation in a spin chain is considered on the base of Shrödinger equation which Hamiltonian depends linearly on control. It is taken into account that the excitation of the first or last spin means that it has greatest amplitude equal to the chain invariant whereas its phase is undefined and can be considered as an additional control variable. The role of this additional control is analyzed via transformation of the original problem with unbounded linear control to the regular derived problem known from the theory of degenerate problems [1, 2], in the same way as in [2]. The overall procedure is demonstrated in computational experiments with the use of visual examples.

  18. Charge transfer through a cytochrome multiheme chain: theory and simulation.

    PubMed

    Burggraf, Fabian; Koslowski, Thorsten

    2014-01-01

    We study sequential charge transfer within a chain of four heme cofactors located in the c-type cytochrome subunit of the photoreaction center of Rhodopseudomonas viridis from a theoretical perspective. Molecular dynamics simulations of the thermodynamic integration type are used to compute two key energies of Marcus' theory of charge transfer, the driving force ∆G and the reorganization energy λ. Due to the small exposure of the cofactors to the solvent and to charged amino acids, the outer sphere contribution to the reorganization energy almost vanishes. Interheme effective electronic couplings are estimated using ab initio wave functions and a well-parameterized semiempirical scheme for long-range interactions. From the resulting charge transfer rates, we conclude that at most the two heme molecules closest to the membrane participate in a fast recharging of the photoreaction center, whereas the remaining hemes are likely to have a different function, such as intermediate electron storage. Finally, we suggest means to verify or falsify this hypothesis. PMID:24055674

  19. Influence of dispersants on trophic transfer of petroleum hydrocarbons in a marine food chain

    SciTech Connect

    Wolfe, M.; Tjeerdema, R.; Sowby, M.

    1995-12-31

    When crude oil is accidentally released into the ocean, it threatens many levels of marine life. Intervention, in the form of chemical dispersing agents, alters the normal behavior of petroleum hydrocarbons (PH) by increasing their functional water solubility and the extent of their exposure to sub-surface organisms. Dispersing agents may modify bioavailability as a result of altered interactions between dispersed PH droplets and organismal cell membranes.The objective of this research was to determine the impact of dispersing agents on PH bioavailability and trophic transfer in primary levels of a marine food chain. Uptake, bioaccumulation, depuration, and metabolic transformation of a model PH, {sup 14}C-naphthalene, were measured and compared for Prudhoe Bay Crude Oil (PBCO) dispersed with Corexit 9527 and undispersed preparations of the water-accommodated fractions (WAF) of PBCO at two salinities and temperatures. The model food chain consisted of Isochrysis galbana and Brachionus plicatilis. Direct aqueous exposure was compared with combined aqueous and dietary exposure. Fractionation and identification of metabolites was done by HPLC co-chromatography with analytical standards, and quantitation was done by liquid scintillation counting. GC-FID characterization of WAF and dispersed oil (DO) preparations shows higher concentrations of petroleum hydrocarbons and a greater number of individual constituents in the dispersed oil preparations.

  20. 'Green' reversible addition-fragmentation chain-transfer (RAFT) polymerization

    NASA Astrophysics Data System (ADS)

    Semsarilar, Mona; Perrier, Sébastien

    2010-10-01

    Reversible addition-fragmentation chain-transfer (RAFT) polymerization has revolutionized the field of polymer synthesis as a versatile tool for the production of complex polymeric architectures. As for all chemical processes, research and development in RAFT have to focus on the design and application of chemical products and processes that have a minimum environmental impact, and follow the principles of 'green' chemistry. In this Review, we summarize some of the green features of the RAFT process, and review the recent advances in the production of degradable polymers obtained from RAFT polymerization. Its use to modify biodegradable and renewable inorganic and organic materials to yield more functional products with enhanced applications is also covered. RAFT is a promising candidate for answering both the increasing need of modern society to employ highly functional polymeric materials and the global requirements for developing sustainable chemicals and processes.

  1. Modification of eucalyptus pulp fiber using silane coupling agents with aliphatic side chains of different length

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The objective of this work was to evaluate the effect of three silane coupling agents with different aliphatic chain lengths on the hydrophobicity of eucalyptus pulp fiber. The three silanes coupling agents used (isobutyltrimethoxysilane, methyltrimethoxysilane, and n-octyltriethoxysilane [OTES]) we...

  2. Poly(vinyl ester) Block Copolymers Synthesized by Reversible Addition−Fragmentation Chain Transfer Polymerizations

    SciTech Connect

    Lipscomb, Corinne E.; Mahanthappa, Mahesh K.

    2009-07-31

    Homopolymerizations and block copolymerizations of vinyl acetate (VAc), vinyl pivalate (VPv), and vinyl benzoate (VBz) by reversible addition-fragmentation chain transfer (RAFT) polymerization have been studied. Polymerizations of VAc initiated with 2,2{prime}-azobis(isobutyronitrile) (AIBN) at 60 C using two different xanthate RAFT agents C{sub 2}H{sub 5}OC(=S)SR (R = -CH(CH{sub 3})CO{sub 2}C{sub 2}H{sub 5} (1) and -CH(CH{sub 3})O{sub 2}CC(CH{sub 3}){sub 3} (2)) were examined to elucidate the dependence of the polydispersities of the resulting polymers on the RAFT agent leaving group R. RAFT agent 2, in which the leaving R-group mimics a growing vinyl ester polymer chain, consistently yields poly(vinyl acetates) having broader polydispersities than those synthesized using 1 (M{sub n} = 3.6-14 kg/mol and M{sub w}/M{sub n} = 1.15-1.33). While VPv exhibits similar controlled polymerization behavior to VAc, RAFT homopolymerizations of VBz mediated by 1 indicate this electron-deficient vinyl ester requires higher temperatures to effect controlled polymerizations to yield polymers having M{sub n} = 4-14 kg/mol and M{sub w}/M{sub n} = 1.29-1.53. Chain extension reactions from xanthate-terminated vinyl ester homopolymers with VAc, VPv, and VBz proceed with variable efficiencies to furnish block copolymers that microphase separate in the melt state as determined by small-angle X-ray scattering.

  3. Preparation of polystyrene brush film by radical chain-transfer polymerization and micromechanical properties

    NASA Astrophysics Data System (ADS)

    Zhao, Jing; Chen, Miao; An, Yanqing; Liu, Jianxi; Yan, Fengyuan

    2008-12-01

    A radical chain-transfer polymerization technique has been applied to graft-polymerize brushes of polystyrene (PSt) on single-crystal silicon substrates. 3-Mercapto-propyltrimethoxysilane (MPTMS), as a chain-transfer agent for grafting, was immobilized on the silicon surface by a self-assembling process. The structure and morphology of the graft-functionalized silicon surfaces were characterized by the means of contact-angle measurement, ellipsometric thickness measurement, Fourier transformation infrared (FTIR) spectroscopy, and atomic force microscopy (AFM). The nanotribological and micromechanical properties of the as-prepared polymer brush films were investigated by frictional force microscopy (FFM), force-volume analysis and scratch test. The results indicate that the friction properties of the grafted polymer films can be improved significantly by the treatment of toluene, and the chemically bonded polystyrene film exhibits superior scratch resistance behavior compared with the spin-coated polystyrene film. The resultant polystyrene brush film is expected to develop as a potential lubrication coating for microelectromechanical systems (MEMS).

  4. Efficient quantum state transfer in an engineered chain of quantum bits

    NASA Astrophysics Data System (ADS)

    Sandberg, Martin; Knill, Emanuel; Kapit, Eliot; Vissers, Michael R.; Pappas, David P.

    2016-03-01

    We present a method of performing quantum state transfer in a chain of superconducting quantum bits. Our protocol is based on engineering the energy levels of the qubits in the chain and tuning them all simultaneously with an external flux bias. The system is designed to allow sequential adiabatic state transfers, resulting in on-demand quantum state transfer from one end of the chain to the other. Numerical simulations of the master equation using realistic parameters for capacitive nearest-neighbor coupling, energy relaxation, and dephasing show that fast, high-fidelity state transfer should be feasible using this method.

  5. Organic cleanliness of the Mars Science Laboratory sample transfer chain.

    PubMed

    Blakkolb, B; Logan, C; Jandura, L; Okon, A; Anderson, M; Katz, I; Aveni, G; Brown, K; Chung, S; Ferraro, N; Limonadi, D; Melko, J; Mennella, J; Yavrouian, A

    2014-07-01

    One of the primary science goals of the Mars Science Laboratory (MSL) Rover, Curiosity, is the detection of organics in Mars rock and regolith. To achieve this, the Curiosity rover includes a robotic sampling system that acquires rock and regolith samples and delivers it to the Sample Analysis at Mars (SAM) instrument on board the rover. In order to provide confidence that any significant organics detection result was Martian and not terrestrial in origin, a requirement was levied on the flight system (i.e., all sources minus the SAM instrument) to impart no more than 36 parts per billion (ppb by weight) of total reduced carbon terrestrial contamination to any sample transferred to the SAM instrument. This very clean level was achieved by a combination of a rigorous contamination control program on the project, and then using the first collected samples for a "dilution cleaning" campaign of the sample chain prior to delivering a sample to the SAM instrument. Direct cleanliness assays of the sample-contacting and other Flight System surfaces during pre-launch processing were used as inputs to determine the number of dilution cleaning samples needed once on Mars, to enable delivery of suitably clean samples to the SAM experiment. Taking into account contaminant redistribution during launch thorough landing of the MSL on Mars, the amount of residue present on the sampling hardware prior to the time of first dilution cleaning sample acquisition was estimated to be 60 ng/cm(2) on exposed outer surfaces of the sampling hardware and 20 ng/cm(2) on internal sample contacting surfaces; residues consisting mainly of aliphatic hydrocarbons and esters. After three dilution cleaning samples, estimated in-sample contamination level for the first regolith sample delivered to the SAM instrument at the Gale Crater "Rocknest" site was bounded at ≤10 ppb total organic carbon. A Project decision to forego ejecting the dilution cleaning sample and instead transfer the first drill

  6. Organic cleanliness of the Mars Science Laboratory sample transfer chain

    NASA Astrophysics Data System (ADS)

    Blakkolb, B.; Logan, C.; Jandura, L.; Okon, A.; Anderson, M.; Katz, I.; Aveni, G.; Brown, K.; Chung, S.; Ferraro, N.; Limonadi, D.; Melko, J.; Mennella, J.; Yavrouian, A.

    2014-07-01

    One of the primary science goals of the Mars Science Laboratory (MSL) Rover, Curiosity, is the detection of organics in Mars rock and regolith. To achieve this, the Curiosity rover includes a robotic sampling system that acquires rock and regolith samples and delivers it to the Sample Analysis at Mars (SAM) instrument on board the rover. In order to provide confidence that any significant organics detection result was Martian and not terrestrial in origin, a requirement was levied on the flight system (i.e., all sources minus the SAM instrument) to impart no more than 36 parts per billion (ppb by weight) of total reduced carbon terrestrial contamination to any sample transferred to the SAM instrument. This very clean level was achieved by a combination of a rigorous contamination control program on the project, and then using the first collected samples for a "dilution cleaning" campaign of the sample chain prior to delivering a sample to the SAM instrument. Direct cleanliness assays of the sample-contacting and other Flight System surfaces during pre-launch processing were used as inputs to determine the number of dilution cleaning samples needed once on Mars, to enable delivery of suitably clean samples to the SAM experiment. Taking into account contaminant redistribution during launch thorough landing of the MSL on Mars, the amount of residue present on the sampling hardware prior to the time of first dilution cleaning sample acquisition was estimated to be 60 ng/cm2 on exposed outer surfaces of the sampling hardware and 20 ng/cm2 on internal sample contacting surfaces; residues consisting mainly of aliphatic hydrocarbons and esters. After three dilution cleaning samples, estimated in-sample contamination level for the first regolith sample delivered to the SAM instrument at the Gale Crater "Rocknest" site was bounded at ≤10 ppb total organic carbon. A Project decision to forego ejecting the dilution cleaning sample and instead transfer the first drill

  7. All possible coupling schemes in XY spin chains for perfect state transfer

    SciTech Connect

    Wang Yaoxiong; Shuang Feng; Rabitz, Herschel

    2011-07-15

    We investigate quantum state transfer in XY spin chains and propose a recursive procedure to construct the nonuniform couplings within these chains of arbitrary length in order to achieve perfect state transfer. We show that this method is capable of finding all possible coupling schemes for perfect state transfer. These schemes, without external control fields, involve analytically identified engineered couplings without the need for dynamical control. The analytical solutions provide all information for coupling design.

  8. Pretty good state transfer of entangled states through quantum spin chains

    NASA Astrophysics Data System (ADS)

    Sousa, Rúben; Omar, Yasser

    2014-12-01

    The XX model with uniform couplings represents the most natural choice for quantum state transfer through spin chains. Given that it has long been established that single-qubit states cannot be transferred with perfect fidelity in this model, the notion of pretty good state transfer has been recently introduced as a relaxation of the constraints on fidelity. In this paper, we study the transfer of multi-qubit entangled and unentangled states through unmodulated spin chains, and we prove that it is possible to have pretty good state transfer of any multi-particle state. This significantly generalizes the previous results on single-qubit state transfer and opens the way to using uniformly coupled spin chains as short-distance quantum channels for the transfer of arbitrary states of any dimension. Our results could be tested with current technology.

  9. Biodegradable Multiblock Poly[N-(2-hydroxypropyl)methacrylamide] via Reversible Addition-Fragmentation Chain Transfer Polymerization and Click Chemistry

    PubMed Central

    Luo, Kui; Yang, Jiyuan; Kopečková, Pavla; Kopeček, Jindřich

    2011-01-01

    A new bifunctional chain transfer agent (CTA) containing alkyne end groups was designed, synthesized and used for direct synthesis of clickable telechelic polymers. Good control of reversible addition-fragmentation chain transfer (RAFT) polymerization of N-(2-hydroxypropyl)methacrylamide (HPMA) was achieved by using the new CTA, as indicated by a linear increase of number average molecular weight (Mn) with conversion and low polydispersity (PDI) (<1.1). In particular, enzymatically degradable multiblock HPMA polymers were readily prepared by subsequent reaction with αω, -diazido oligopeptide (GFLG) sequence via CuI catalyzed alkyne-azide cycloaddition. Upon exposure of high molecular weight fractions of multiblock polyHPMA to papain or cathepsin B, the polymer was degraded into segments of molecular weight and narrow polydispersity similar to those of the initial telechelic polyHPMA. PMID:21552355

  10. A Demand-Driven Approach for a Multi-Agent System in Supply Chain Management

    NASA Astrophysics Data System (ADS)

    Kovalchuk, Yevgeniya; Fasli, Maria

    This paper presents the architecture of a multi-agent decision support system for Supply Chain Management (SCM) which has been designed to compete in the TAC SCM game. The behaviour of the system is demand-driven and the agents plan, predict, and react dynamically to changes in the market. The main strength of the system lies in the ability of the Demand agent to predict customer winning bid prices - the highest prices the agent can offer customers and still obtain their orders. This paper investigates the effect of the ability to predict customer order prices on the overall performance of the system. Four strategies are proposed and compared for predicting such prices. The experimental results reveal which strategies are better and show that there is a correlation between the accuracy of the models' predictions and the overall system performance: the more accurate the prediction of customer order prices, the higher the profit.

  11. [Preparation of epitope imprinted particles for transferrin recognition by reversible addition fragmentation chain transfer strategy].

    PubMed

    Li, Qinran; Yang, Kaiguang; Li, Senwu; Liu, Jianxi; Zhang, Lihua; Liang, Zhen; Zhang, Yukui

    2014-10-01

    A kind of novel epitope surface imprinted particles was prepared by the reversible addition fragmentation chain transfer (RAFT) strategy. The epitope of transferrin, N-terminal peptide of the protein with nine amino acid residues, was chosen as the template and immobi- lized with covalent interaction on the surface of silica particles through the truss arm glutaraldehyde. The living/controlled polymerization was initialed by 2,2'-azobisisobutyronitrile (AIBN) at 70 °C in the solution of N,N-dimethylformamide, with the regulation by triothioester agent 2-(dodecylthiocarbonothioylthio)-2-methylpropanoic acid. Methacrylic acid and 2-hydroxyethyl methacrylate were chosen as the functional monomers and N, N-methylenebisacrylamide was chosen as the cross-linker in this polymerization. For this material, the binding capacity of the nine residue peptide could reach 2.36 mg/g with the imprinting factor (IF) of 1.89, while that for transferrin could reach 4.98 mg/g with IF of 1.61. The equilibrium could be achieved in 120 min for the transferrin recognition. In multi-protein competitive recognition, the imprinted factor of transferrin was the highest in the mixture of transferrin and other competitive proteins, such as cytochrome C and β-lactoglobulin. The results indicated that these epitope surface imprinted particles with RAFT strategy could recognize not only the nine residue peptide but also the transferrin with good selectivity, high binding capacity and fast mass transfer. PMID:25739262

  12. Detection of biological warfare agents using the polymerase chain reaction. Final report, June-August 1991

    SciTech Connect

    Mann, B.J.

    1992-09-01

    The detection of biological warfare agents is an important mission for the U.S. Army. This report explores the feasibility of using the polymerase chain reaction as a means of rapid detection of biological warfare agents. Two levels of detection are proposed. The first level is group specific detection, using primers derived from 16S rDNA sequences, to detect various groups of pathogenic bacteria. The second level is species-specific detection using primers derived from DNA sequences, unique to each pathogenic organism targeted for detection. Specific examples of Vibrio cholerae, Francisella tularensis, Yersinia pestis, Staphylococcus aureus, and Bacillus anthracis are described.

  13. Quantum error correction for state transfer in noisy spin chains

    NASA Astrophysics Data System (ADS)

    Kay, Alastair

    2016-04-01

    Can robustness against experimental imperfections and noise be embedded into a quantum simulation? In this paper, we report on a special case in which this is possible. A spin chain can be engineered such that, in the absence of imperfections and noise, an unknown quantum state is transported from one end of the chain to the other, due only to the intrinsic dynamics of the system. We show that an encoding into a standard error-correcting code (a Calderbank-Shor-Steane code) can be embedded into this simulation task such that a modified error-correction procedure on readout can recover from sufficiently low rates of noise during transport.

  14. Restricted access chiral stationary phase synthesized via reversible addition-fragmentation chain-transfer polymerization for direct analysis of biological samples by high performance liquid chromatography.

    PubMed

    Song, Wen-Jun; Wei, Ji-Ping; Wang, Su-Ying; Wang, Huai-Song

    2014-06-17

    Novel hydrophilic microparticles containing β-cyclodextrin (β-CD) were prepared via one-pot synthesis using reversible addition-fragmentation chain-transfer (RAFT) precipitation polymerization, a "controlled/living" radical polymerization technique. The polymerization was initiated by hydrophilic macromolecular chain-transfer agent [poly(2-hydroxyethyl methacrylate), PHEMA]. The hydrophilic PHEMA on the surface of microparticles can well improve their surface hydrophilicity and lead to their biological compatibility. As chiral restricted access material (RAM), the hydrophilic microparticles can be used for determination of enantiomers in biological samples with direct injection via HPLC analysis. PMID:24890695

  15. 17 CFR 240.17Ad-17 - Transfer agents' obligation to search for lost securityholders.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ..., each recordkeeping transfer agent shall conduct two data base searches using at least one information data base service. The transfer agent shall search by taxpayer identification number or by name if a.... Such data base searches must be conducted without charge to a lost securityholder and with...

  16. 17 CFR 240.17Ad-17 - Transfer agents' obligation to search for lost securityholders.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... search for lost securityholders. 240.17Ad-17 Section 240.17Ad-17 Commodity and Securities Exchanges... Company Rules § 240.17Ad-17 Transfer agents' obligation to search for lost securityholders. (a)(1) Every..., each recordkeeping transfer agent shall conduct two data base searches using at least one...

  17. 17 CFR 240.17Ad-17 - Transfer agents' obligation to search for lost securityholders.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ..., each recordkeeping transfer agent shall conduct two data base searches using at least one information data base service. The transfer agent shall search by taxpayer identification number or by name if a.... Such data base searches must be conducted without charge to a lost securityholder and with...

  18. Surface modification of carbon nanotubes via combination of mussel inspired chemistry and chain transfer free radical polymerization

    NASA Astrophysics Data System (ADS)

    Wan, Qing; Tian, Jianwen; Liu, Meiying; Zeng, Guangjian; Huang, Qiang; Wang, Ke; Zhang, Qingsong; Deng, Fengjie; Zhang, Xiaoyong; Wei, Yen

    2015-08-01

    In this work, a novel strategy for surface modification of carbon nanotubes (CNTs) was developed via combination of mussel inspired chemistry and chain transfer free radical polymerization. First, pristine CNTs were functionalized with polydopamine (PDA), which is formed via self-polymerization of dopamine in alkaline conditions. These PDA functionalized CNTs can be further reacted with amino-terminated polymers (named as PDMC), which was synthesized through chain transfer free radical polymerization using cysteamine hydrochloride as chain transfer agent and methacryloxyethyltrimethyl ammonium chloride as the monomer. PDMC perfectly conjugated with CNT-PDA was ascertained by a series of characterization techniques including transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FT-IR), thermal gravimetric analysis (TGA) and X-ray photoelectron spectroscopy (XPS). The dispersibility of obtained CNT nanocomposites (named as CNT-PDA-PDMC) was further examined. Results showed that the dispersibility of CNT-PDA-PDMC in aqueous and organic solutions was obviously enhanced. Apart from PDMC, many other amino-terminated polymers can also be used to functionalization of CNTs via similar strategy. Therefore, the method described in this work should be a general strategy for fabrication various polymer nanocomposites.

  19. Energy Transfers in Coupled Ordered Granular Chains with No Precompression

    NASA Astrophysics Data System (ADS)

    Vakakis, Alexander; Hasan, Arif M.; Starosvetsky, Yuli; Manevitch, Leonid I.

    2013-03-01

    We study the dynamics of coupled one-dimensional granular chains mounted on elastic foundations. No dissipative effects, such as plasticity or dry friction effects are taken into account in our analysis. Assuming no pre-compression between beads, the dynamics of the system under consideration is strongly nonlinear and, in an acoustic analogy they can be viewed as `sonic vacua'. Sources of strong nonlinearity in these systems are nonlinearizable Hertzian interactions between adjacent beads in compression, and also possible separations between beads in the absence of compressive forces leading to bead collisions. We find that demonstrate that in weakly coupled granular chains there can occur strong energy exchanges in the form of nonlinear beat phenomena of spatially periodic traveling waves, stationary breathers or propagating breathers. We employ analytical techniques to study these dynamical phenomena. This work was supported by MURI grant US ARO W911NF-09-1-0436. Dr. David Stepp is the grant monitor.

  20. Transferring information through a mixed-five-spin chain channel

    NASA Astrophysics Data System (ADS)

    Arian Zad, Hamid; Movahhedian, Hossein

    2016-08-01

    We initially introduce one-dimensional mixed-five-spin chain with Ising-XY model which includes mixture of spins-1/2 and spins-1. Here, it is considered that nearest spins (1,1/2) have Ising-type interaction and nearest spins (1/2,1/2) have both XY-type and Dzyaloshinskii–Moriya (DM) interactions together. Nearest spins (1,1) have XX Heisenberg interaction. This system is in the vicinity of an external homogeneous magnetic field B in thermal equilibrium state. We promote the quantum information transmitting protocol verified for a normal spin chain with simple model (refer to Rossini D, Giovannetti V and Fazio R 2007 Int. J. Quantum Infor. 5 439) (widely in reference: Giovannetti V and Fazio R 2005 Phys. Rev. A 71 032314) by means of considering the suggested mixed-five-spin chain as a quantum communication channel for transmitting both qubits and qutrits ideally. Hence, we investigate some useful quantities such as quantum capacity and quantum information transmission rate for the system. Finally, we conclude that, when the DM interaction between spins (1/2,1/2) increases the system is a more ideal channel for transmitting information.

  1. Spin chains and electron transfer at stepped silicon surfaces

    NASA Astrophysics Data System (ADS)

    Erwin, Steven; Aulbach, Julian; Claessen, Ralph; Schaefer, Joerg

    Stepped silicon surfaces oriented between Si(111) and Si(001) show unusual behavior when submonolayer amounts of gold are adsorbed: they self-assemble to form arrays of steps with virtually perfect structural order. Known examples include Si(553), Si(557), and Si(775). For the first two of these there is, in addition, strong theoretical and experimental evidence that the silicon step edges are spin polarized, raising the possibility of a magnetically ordered ground state at a silicon surface. The situation is different, however, for Si(775): theory and experiment both show that spin polarization does not occur. Here we use density-functional theory and scanning tunneling microscopy to develop a physically transparent picture explaining the formation of these 'spin chains' on the family of Si(hhk)-Au surfaces. Specifically, we explain why spin chains form on particular silicon (hhk) orientations but not on others. Finally, we use this understanding to propose strategies for using surface chemistry to control the formation or suppression of spin chains on Si(hhk)-Au surfaces.

  2. Spin Chains and Electron Transfer at Stepped Silicon Surfaces.

    PubMed

    Aulbach, J; Erwin, S C; Claessen, R; Schäfer, J

    2016-04-13

    High-index surfaces of silicon with adsorbed gold can reconstruct to form highly ordered linear step arrays. These steps take the form of a narrow strip of graphitic silicon. In some cases--specifically, for Si(553)-Au and Si(557)-Au--a large fraction of the silicon atoms at the exposed edge of this strip are known to be spin-polarized and charge-ordered along the edge. The periodicity of this charge ordering is always commensurate with the structural periodicity along the step edge and hence leads to highly ordered arrays of local magnetic moments that can be regarded as "spin chains." Here, we demonstrate theoretically as well as experimentally that the closely related Si(775)-Au surface has--despite its very similar overall structure--zero spin polarization at its step edge. Using a combination of density-functional theory and scanning tunneling microscopy, we propose an electron-counting model that accounts for these differences. The model also predicts that unintentional defects and intentional dopants can create local spin moments at Si(hhk)-Au step edges. We analyze in detail one of these predictions and verify it experimentally. This finding opens the door to using techniques of surface chemistry and atom manipulation to create and control silicon spin chains. PMID:26974012

  3. Radiative transfer calculated from a Markov chain formalism

    NASA Technical Reports Server (NTRS)

    Esposito, L. W.; House, L. L.

    1978-01-01

    The theory of Markov chains is used to formulate the radiative transport problem in a general way by modeling the successive interactions of a photon as a stochastic process. Under the minimal requirement that the stochastic process is a Markov chain, the determination of the diffuse reflection or transmission from a scattering atmosphere is equivalent to the solution of a system of linear equations. This treatment is mathematically equivalent to, and thus has many of the advantages of, Monte Carlo methods, but can be considerably more rapid than Monte Carlo algorithms for numerical calculations in particular applications. We have verified the speed and accuracy of this formalism for the standard problem of finding the intensity of scattered light from a homogeneous plane-parallel atmosphere with an arbitrary phase function for scattering. Accurate results over a wide range of parameters were obtained with computation times comparable to those of a standard 'doubling' routine. The generality of this formalism thus allows fast, direct solutions to problems that were previously soluble only by Monte Carlo methods. Some comparisons are made with respect to integral equation methods.

  4. Long-range doublon transfer in a dimer chain induced by topology and ac fields.

    PubMed

    Bello, M; Creffield, C E; Platero, G

    2016-01-01

    The controlled transfer of particles from one site of a spatial lattice to another is essential for many tasks in quantum information processing and quantum communication. In this work we study how to induce long-range transfer between the two ends of a dimer chain, by coupling states that are localized just on the chain's end-points. This has the appealing feature that the transfer occurs only between the end-points - the particle does not pass through the intermediate sites-making the transfer less susceptible to decoherence. We first show how a repulsively bound-pair of fermions, known as a doublon, can be transferred from one end of the chain to the other via topological edge states. We then show how non-topological surface states of the familiar Shockley or Tamm type can be used to produce a similar form of transfer under the action of a periodic driving potential. Finally we show that combining these effects can produce transfer by means of more exotic topological effects, in which the driving field can be used to switch the topological character of the edge states, as measured by the Zak phase. Our results demonstrate how to induce long range transfer of strongly correlated particles by tuning both topology and driving. PMID:26932406

  5. Kinetics of electron transfer through the respiratory chain.

    PubMed Central

    Jin, Qusheng; Bethke, Craig M

    2002-01-01

    We show that the rate at which electrons pass through the respiratory chain in mitochondria and respiring prokaryotic cells is described by the product of three terms, one describing electron donation, one acceptance, and a third, the thermodynamic drive. We apply the theory of nonequilibrium thermodynamics in the context of the chemiosmotic model of proton translocation and energy conservation. This approach leads to a closed-form expression that predicts steady-state electron flux as a function of chemical conditions and the proton motive force across the mitochondrial inner membrane or prokaryotic cytoplasmic membrane. The rate expression, derived considering reverse and forward electron flow, is the first to account for both thermodynamic and kinetic controls on the respiration rate. The expression can be simplified under specific conditions to give rate laws of various forms familiar in cellular physiology and microbial ecology. The expression explains the nonlinear dependence of flux on electrical potential gradient, its hyperbolic dependence on substrate concentration, and the inhibiting effects of reaction products. It provides a theoretical basis for investigating life under unusual conditions, such as microbial respiration in alkaline waters. PMID:12324402

  6. Kinetics of electron transfer through the respiratory chain.

    PubMed

    Jin, Qusheng; Bethke, Craig M

    2002-10-01

    We show that the rate at which electrons pass through the respiratory chain in mitochondria and respiring prokaryotic cells is described by the product of three terms, one describing electron donation, one acceptance, and a third, the thermodynamic drive. We apply the theory of nonequilibrium thermodynamics in the context of the chemiosmotic model of proton translocation and energy conservation. This approach leads to a closed-form expression that predicts steady-state electron flux as a function of chemical conditions and the proton motive force across the mitochondrial inner membrane or prokaryotic cytoplasmic membrane. The rate expression, derived considering reverse and forward electron flow, is the first to account for both thermodynamic and kinetic controls on the respiration rate. The expression can be simplified under specific conditions to give rate laws of various forms familiar in cellular physiology and microbial ecology. The expression explains the nonlinear dependence of flux on electrical potential gradient, its hyperbolic dependence on substrate concentration, and the inhibiting effects of reaction products. It provides a theoretical basis for investigating life under unusual conditions, such as microbial respiration in alkaline waters. PMID:12324402

  7. Copper transfer and influence on a marine food chain

    SciTech Connect

    Edding, M.; Tala, F.

    1996-12-31

    Copper is an essential element, required for normal growth by all plants and animals; and a regular constituent in the environment (Lewis and Cave 1982; Lewis 1994). This heavy metal is an essential micronutrient that at higher concentrations can be deleterious to algae and other aquatic biota (Chang and Sibley 1993). Copper toxicity to algae depends upon the individual species, their physiological and environmental conditions, and the chemical forms of metal in the medium (Sunda and Gullard 1976). When copper is accumulated by phytoplankton it can be transferred and may produce toxic effects on zooplankton (Wikfors and Ukeles 1982). Different species of microalgae present different capacities of resistance to copper. Cyanophyceae pre-cultured in a Cu-enriched medium (635 {mu}gCu{center_dot}L{sup {minus}1}) showed an EC{sub 50} that could reach 318 {mu}gCu{center_dot}L{sup {minus}1} for Plectonema radiosum and 339 {mu}gCu{center_dot}L{sup {minus}1} in Phormidium sp. (Takamura et al. 1990). Scenedesmus, Selenastrum and Chlorella were reported able to accumulate copper and other metal ions with an efficiency of 67-98% (Brady et al. 1994). Also, Dunaliella resisted concentrations form 0.38 mgCu{center_dot}L{sup {minus}1} (D. minuta) up to 50.8 mgCu{center_dot}L{sup {minus}1} (D. acidophila), depending on the pH of the medium (Grimmler et al. 1991). One the microalgae are copper-enriched, the copper that is part of the cell can be transferred to the surrounding water and to its predator producing uncertain effects. This study observed the effect of copper on the growth of Dunaliella tertiolecta and Isochrysis galbana that are currently used as food for hatchery-grown scallop larvae (Argopecten purpuratus). We observed the path of copper form the water column into the microalgal cell and the effect of copper-enriched food on the scallop larvae. 16 refs., 3 figs., 2 tabs.

  8. Bioaccumulation and food chain transfer of corrosion products from radioactive stainless steel

    SciTech Connect

    Young, J.S.

    1986-07-01

    Two sets of experiments were conducted to determine if corrosion products from radioactive Type 347 stainless steel could be biologically transferred from sediment through a marine food chain, and whether corrosion products dissolved in seawater could be bioaccumulated and then eliminated. Corrosion products containing /sup 60/Co and /sup 63/Ni from the radioactive stainless steel were introduced into marine sediments. Infaunal polychaete worms exposed to these sediments bioaccumulated the radionuclides. The feeding of these worms to shrimp and fish resulted in a trophic transfer of the radioactive products across a one-step food chain. The magnitude of the transfers are described in terms of transfer factors. Dissolved corrosion products as measured by the radionuclides were also bioaccumulated by shrimp and fish concentrating more than fish. Concentration factors were calculated.

  9. Bacteriophage-like Particles Associated with the Gene Transfer Agent of Methanococcus Voltale PS

    NASA Technical Reports Server (NTRS)

    Bertani, G.; Eiserling, F.; Pushkin, A.; Gingery, M.

    1999-01-01

    The methanogenic archaebacterium Methanococus voltae (strain PS) is known to produce a filterable, DNase resistant agent (called VTA, for voltae transfer agent), which carries very small fragments (4,400 base pairs) of bacterial DNA and is able to transduce bacterial genes between derivatives of the strain.

  10. Passive transfer of maternal immunity in the dromedary (Camelus dromedarius), involvement of heavy chain antibodies.

    PubMed

    Salhi, Imed; Bessalah, Salma; Mbarek, Sonia Ben; Chniter, Mohamed; Seddik, Mabrouk-Mouldi; Khorchani, Touhami; Hammadi, Mohamed

    2015-03-01

    In many mammalian species, newborns are agammaglobulinemic; thus, colostrum and milk are the main sources of early protective antibodies. These antibodies are produced in the mother's serum and transferred to mammalian glands a few days before parturition. Here, we have studied the transfer of immunity from a she-camel immunized with human serum albumin (HSA) to her calf via colostrum and milk. Our results show that HSA-specific antibodies are produced in the mother's serum and are subsequently transferred to her colostrum. These specific antibodies are then transferred by suckling to the calf. The calf serum did not contain HSA-reactive antibodies at parturition and before the first feed, after suckling, a rise in reactivity was observed peaking at 24 h postpartum. The involvement of heavy chain antibodies (HCAbs) in the process of immunity transfer was also examined, and it was found that they were also transferred from the colostrum to the calf serum like conventional antibodies. PMID:25547806

  11. Long-range doublon transfer in a dimer chain induced by topology and ac fields

    NASA Astrophysics Data System (ADS)

    Bello, M.; Creffield, C. E.; Platero, G.

    2016-03-01

    The controlled transfer of particles from one site of a spatial lattice to another is essential for many tasks in quantum information processing and quantum communication. In this work we study how to induce long-range transfer between the two ends of a dimer chain, by coupling states that are localized just on the chain’s end-points. This has the appealing feature that the transfer occurs only between the end-points - the particle does not pass through the intermediate sites-making the transfer less susceptible to decoherence. We first show how a repulsively bound-pair of fermions, known as a doublon, can be transferred from one end of the chain to the other via topological edge states. We then show how non-topological surface states of the familiar Shockley or Tamm type can be used to produce a similar form of transfer under the action of a periodic driving potential. Finally we show that combining these effects can produce transfer by means of more exotic topological effects, in which the driving field can be used to switch the topological character of the edge states, as measured by the Zak phase. Our results demonstrate how to induce long range transfer of strongly correlated particles by tuning both topology and driving.

  12. Long-range doublon transfer in a dimer chain induced by topology and ac fields

    PubMed Central

    Bello, M.; Creffield, C. E.; Platero, G.

    2016-01-01

    The controlled transfer of particles from one site of a spatial lattice to another is essential for many tasks in quantum information processing and quantum communication. In this work we study how to induce long-range transfer between the two ends of a dimer chain, by coupling states that are localized just on the chain’s end-points. This has the appealing feature that the transfer occurs only between the end-points – the particle does not pass through the intermediate sites–making the transfer less susceptible to decoherence. We first show how a repulsively bound-pair of fermions, known as a doublon, can be transferred from one end of the chain to the other via topological edge states. We then show how non-topological surface states of the familiar Shockley or Tamm type can be used to produce a similar form of transfer under the action of a periodic driving potential. Finally we show that combining these effects can produce transfer by means of more exotic topological effects, in which the driving field can be used to switch the topological character of the edge states, as measured by the Zak phase. Our results demonstrate how to induce long range transfer of strongly correlated particles by tuning both topology and driving. PMID:26932406

  13. Sensitive Detection of Thirteen Bacterial Vaginosis-Associated Agents Using Multiplex Polymerase Chain Reaction

    PubMed Central

    Malaguti, Natália; Bahls, Larissa Danielle; Uchimura, Nelson Shozo; Gimenes, Fabrícia; Consolaro, Marcia Edilaine Lopes

    2015-01-01

    Bacterial vaginosis (BV) is characterized by a polymicrobial proliferation of anaerobic bacteria and depletion of lactobacilli, which are components of natural vaginal microbiota. Currently, there are limited conventional methods for BV diagnosis, and these methods are time-consuming, expensive, and rarely allow for the detection of more than one agent simultaneously. Therefore, we conceived and validated a multiplex polymerase chain reaction (M-PCR) assay for the simultaneous screening of thirteen bacterial vaginosis-associated agents (BV-AAs) related to symptomatic BV: Gardnerella vaginalis, Mobiluncus curtisii, Mobiluncus mulieris, Bacteroides fragilis, Mycoplasma hominis, Atopobium vaginae, Ureaplasma urealyticum, Megasphaera type I, Clostridia-like bacteria vaginosis-associated bacteria (BVABs) 1, 2, and 3, Sneathia sanguinegens, and Mycoplasma genitalium. The overall validation parameters of M-PCR compared to single PCR (sPCR) were extremely high, including agreement of 99.1% and sensitivity, specificity, and positive predictive values of 100.0%, negative predictive value of 97.0%, accuracy of 99.3%, and agreement with Nugent results of 100.0%. The prevalence of BV-AAs was very high (72.6%), and simultaneous agents were detected in 53.0%, which demonstrates the effectiveness of the M-PCR assay. Therefore, the M-PCR assay has great potential to impact BV diagnostic methods in vaginal samples and diminish associated complications in the near future. PMID:26078959

  14. Dynamic modeling system for the transfer of radioactivity in terrestrial food chains

    SciTech Connect

    Simmonds, J.R.; Linsley, G.S.

    1981-11-01

    A dynamic modeling system is described for the transfer of radionuclides in terrestrial food chains. The main features of the system are its ability to predict the time dependence of the major transfer processes and its flexibility and applicability to a range of contamination scenarios. The modeling system is regarded as a basic framework on which more realistic models can be based, given the availability of reliable environmental transfer data. An example of such a development is included for /sup 90/Sr in the pasture-cow-milk pathway. The model predicts annual average concentrations of /sup 90/Sr in milk caused by fallout in the United Kingdom to within 15% of measured values for over most of the 20-y period for which data exist. It makes possible the evaluation of the time dependence of the contributions of various transfer processes. Following acute releases to the atmosphere or releases in any other contamination scenario where direct deposition is absent, certain pathways often not considered in food-chain models, such as the external contamination of plants caused by resuspension processes or the ingestion of contaminants together with soil by grazing animals, are shown to be potentially important in the transfer of activity to man. The main application of dynamic food-chain models is the prediction of the consequences of accidental releases to the terrestrial environment. The predictions can be used in planning countermeasures and in assessing the health, economic, and social impacts of accidental release.

  15. Effects of Nanoparticle Morphology and Acyl Chain Length on Spontaneous Lipid Transfer Rates

    DOE PAGESBeta

    Xia, Yan; Li, Ming; Charubin, Kamil; Liu, Ying; Heberle, Frederick A.; Katsaras, John; Jing, Benxin; Zhu, Yingxi; Nieh, Mu-Ping

    2015-11-05

    In this paper, we report on studies of lipid transfer rates between different morphology nanoparticles and lipids with different length acyl chains. The lipid transfer rate of dimyristoylphosphatidylcholine (di-C14, DMPC) in discoidal “bicelles” (0.156 h–1) is 2 orders of magnitude greater than that of DMPC vesicles (ULVs) (1.1 × 10–3 h–1). For both bicellar and ULV morphologies, increasing the acyl chain length by two carbons [going from di-C14 DMPC to di-C16, dipalmitoylphosphatidylcholine (DPPC)] causes lipid transfer rates to decrease by more than 2 orders of magnitude. Results from small angle neutron scattering (SANS), differential scanning calorimetry (DSC), and fluorescence correlationmore » spectroscopy (FCS) are in good agreement. Finally, the present studies highlight the importance of lipid dynamic processes taking place in different morphology biomimetic membranes.« less

  16. Effects of Nanoparticle Morphology and Acyl Chain Length on Spontaneous Lipid Transfer Rates

    SciTech Connect

    Xia, Yan; Li, Ming; Charubin, Kamil; Liu, Ying; Heberle, Frederick A.; Katsaras, John; Jing, Benxin; Zhu, Yingxi; Nieh, Mu-Ping

    2015-11-05

    In this paper, we report on studies of lipid transfer rates between different morphology nanoparticles and lipids with different length acyl chains. The lipid transfer rate of dimyristoylphosphatidylcholine (di-C14, DMPC) in discoidal “bicelles” (0.156 h–1) is 2 orders of magnitude greater than that of DMPC vesicles (ULVs) (1.1 × 10–3 h–1). For both bicellar and ULV morphologies, increasing the acyl chain length by two carbons [going from di-C14 DMPC to di-C16, dipalmitoylphosphatidylcholine (DPPC)] causes lipid transfer rates to decrease by more than 2 orders of magnitude. Results from small angle neutron scattering (SANS), differential scanning calorimetry (DSC), and fluorescence correlation spectroscopy (FCS) are in good agreement. Finally, the present studies highlight the importance of lipid dynamic processes taking place in different morphology biomimetic membranes.

  17. Chaining direct memory access data transfer operations for compute nodes in a parallel computer

    DOEpatents

    Archer, Charles J.; Blocksome, Michael A.

    2010-09-28

    Methods, systems, and products are disclosed for chaining DMA data transfer operations for compute nodes in a parallel computer that include: receiving, by an origin DMA engine on an origin node in an origin injection FIFO buffer for the origin DMA engine, a RGET data descriptor specifying a DMA transfer operation data descriptor on the origin node and a second RGET data descriptor on the origin node, the second RGET data descriptor specifying a target RGET data descriptor on the target node, the target RGET data descriptor specifying an additional DMA transfer operation data descriptor on the origin node; creating, by the origin DMA engine, an RGET packet in dependence upon the RGET data descriptor, the RGET packet containing the DMA transfer operation data descriptor and the second RGET data descriptor; and transferring, by the origin DMA engine to a target DMA engine on the target node, the RGET packet.

  18. Shape control of the magnetic iron oxide nanoparticles under different chain length of reducing agents

    SciTech Connect

    Ngoi, Kuan Hoon; Chia, Chin-Hua Zakaria, Sarani; Chiu, Wee Siong

    2015-09-25

    We report on the effect of using reducing agents with different chain-length on the synthesis of iron oxide nanoparticles by thermal decomposition of iron (III) acetylacetonate in 1-octadecene. This modification allows us to control the shape of nanoparticles into spherical and cubic iron oxide nanoparticles. The highly monodisperse 14 nm spherical nanoparticles are obtained under 1,2-dodecanediol and average 14 nm edge-length cubic iron oxide nanoparticles are obtained under 1,2-tetradecanediol. The structural characterization such as transmission electron microscope (TEM) and X-ray diffraction (XRD) shows similar properties between two particles with different shapes. The vibrating sample magnetometer (VSM) shows no significant difference between spherical and cubic nanoparticles, which are 36 emu/g and 37 emu/g respectively and superparamagnetic in nature.

  19. Study on the performance of polycarboxylate-based superplasticizers synthesized by reversible addition-fragmentation chain transfer (RAFT) polymerization

    NASA Astrophysics Data System (ADS)

    Yu, Binbin; Zeng, Zhong; Ren, Qinyu; Chen, Yang; Liang, Mei; Zou, Huawei

    2016-09-01

    A series of block type polycarboxylate-based superplasticizers (PCs) with different molecular architectures were synthesized with macromonomer butenyl alkylene polyoxyethylene-polyoxypropylene ether (BAPP) and acrylic acid (AA) by reversible addition-fragmentation chain transfer (RAFT) polymerization. Fourier-Transformed Infrared (FTIR) Spectroscopy and dynamic light scattering (DLS) were applied to investigate the PCs' molecular structure. The dispersion capacity of the PCs in cement were also measured, and the results showed that the polycarboxylic dispersing agents prepared by this method were suitable for portlant cement. It was found that the PCs could affect the hydration process, which was performed through retarding the generation of ettringite in the hydrated product. Our studies with X-ray diffraction (XRD), scanning electron microscopy (SEM) and compressive strength measurement of hydrated production were all supporting this conclusion.

  20. Olefin polymerization at bis(pentamethylcyclopentadienyl) zirconium and -hafnium centers: Chain-transfer mechanisms

    SciTech Connect

    Resconi, L.; Piemontesi, F.; Franciscono, G.

    1992-01-29

    Chain transfer via {beta}-CH{sub 3} elimination by a homogeneous bimetallic Ziegler-Natta propylene polymerization catalyst is reported. Propylene is converted by Cp{sup {double_dagger}}{sub 2}MCl{sub 2}/MAO catalysts (Cp{sup {double_dagger}} = pentamethylcyclopentadienyl; M=Zr, Hf; MAO = methylalumoxane) to atactic propylene oligomers and low polymers. GC-MS and {sup 1}H and {sup 13}C NMR analyses of the oligomers obtained at {degrees}C (P{sub n} {approx} 4.5 for Zr, 3.4 for Hf) show these products to be mainly allyl- and isobutyl-terminated (1/1 ratio). The allyl/vinylidene ratio is 92/8 for Zr and 98/2 for Hf. No other unsaturated end groups could be detected. This end group structure is produced by first monomer insertion into the M-CH{sub 3} bond and then chain transfer by {beta}-CH{sub 3} elimination. On the contrary, Cp{sup {double_dagger}}{sub 2}MCl{sub 2}/MAO promotes 1-butene polymerization with the chain transfer being exclusively {beta}-H elimination and transfer to Al: no {beta}-ethyl elimination could be detected. The behavior of these catalysts toward propylene and 1-butene is compared with known Cp{sub 2}MCl{sub 2}/MAO catalysts. 37 refs., 11 figs., 5 tabs.

  1. Tunable self-assembled spin chains of strongly interacting cold atoms for demonstration of reliable quantum state transfer

    NASA Astrophysics Data System (ADS)

    Loft, N. J. S.; Marchukov, O. V.; Petrosyan, D.; Zinner, N. T.

    2016-04-01

    We have developed an efficient computational method to treat long, one-dimensional systems of strongly interacting atoms forming self-assembled spin chains. Such systems can be used to realize many spin chain model Hamiltonians tunable by the external confining potential. As a concrete demonstration, we consider quantum state transfer in a Heisenberg spin chain and we show how to determine the confining potential in order to obtain nearly perfect state transfer.

  2. A crystalline singlet phosphinonitrene: a nitrogen atom-transfer agent.

    PubMed

    Dielmann, Fabian; Back, Olivier; Henry-Ellinger, Martin; Jerabek, Paul; Frenking, Gernot; Bertrand, Guy

    2012-09-21

    A variety of transition metal-nitrido complexes (metallonitrenes) have been isolated and studied in the context of modeling intermediates in biological nitrogen fixation by the nitrogenase enzymes and the industrial Haber-Bosch hydrogenation of nitrogen gas into ammonia. In contrast, nonmetallic nitrenes have so far only been spectroscopically observed at low temperatures, despite their intermediacy in a range of organic reactions. Here, we report the synthesis of a bis(imidazolidin-2-iminato)phosphinonitrene, which is stable at room temperature in solution and can even be isolated in the solid state. The bonding between phosphorus and nitrogen is analogous to that observed for metallonitrenes. We also show that this nitrido phosphorus derivative can be used to transfer a nitrogen atom to organic fragments, a difficult task for transition metal-nitrido complexes. PMID:22997335

  3. Electrode assemblies composed of redox cascades from microbial respiratory electron transfer chains

    SciTech Connect

    Gates, Andrew J.; Marritt, Sophie; Bradley, Justin; Shi, Liang; McMillan, Duncan G.; Jeuken, Lars J.; Richardson, David; Butt, Julea N.

    2013-10-01

    Respiratory and photosynthetic electron transfer chains are dependent on vectorial electron transfer through a series of redox proteins. Examples include electron transfer from NapC to NapAB nitrate reductase in Paracoccus denitrificans and from CymA to Fcc3 (flavocytochrome c3) fumarate reductase in Shewanella oneidensis MR-1. In the present article, we demonstrate that graphite electrodes can serve as surfaces for the stepwise adsorption of NapC and NapAB, and the stepwise adsorption of CymA and Fcc3. Aspects of the catalytic properties of these assemblies are different from those of NapAB and Fcc3 adsorbed in isolation. We propose that this is due to the formation of NapC-NapAB and of CymA-Fcc3 complexes that are capable of supporting vectorial electron transfer.

  4. Universal scheme for finite-probability perfect transfer of arbitrary multispin states through spin chains

    SciTech Connect

    Man, Zhong-Xiao; An, Nguyen Ba; Xia, Yun-Jie; Kim, Jaewan

    2014-12-15

    In combination with the theories of open system and quantum recovering measurement, we propose a quantum state transfer scheme using spin chains by performing two sequential operations: a projective measurement on the spins of ‘environment’ followed by suitably designed quantum recovering measurements on the spins of interest. The scheme allows perfect transfer of arbitrary multispin states through multiple parallel spin chains with finite probability. Our scheme is universal in the sense that it is state-independent and applicable to any model possessing spin–spin interactions. We also present possible methods to implement the required measurements taking into account the current experimental technologies. As applications, we consider two typical models for which the probabilities of perfect state transfer are found to be reasonably high at optimally chosen moments during the time evolution. - Highlights: • Scheme that can achieve perfect quantum state transfer is devised. • The scheme is state-independent and applicable to any spin-interaction models. • The scheme allows perfect transfer of arbitrary multispin states. • Applications to two typical models are considered in detail.

  5. Transfer of Metals in Food Chain: An Example with Copper and Lettuce

    NASA Astrophysics Data System (ADS)

    Vincevica-Gaile, Zane; Klavins, Maris

    2012-12-01

    Present study investigated the possible transfer of metals in the food chain (from soil to edible plants). The experiment was done with lettuce Lactuca sativa grown in different types of soil contaminated with copper (Cu2+) in various concentrations, with or without addition of humic substances. The highest content of copper was detected in lettuce samples grown in soils with lower levels of organic matter, thus indicating the importance of soil organics in metal transfer routes and accumulation rates in plants. It was found that copper accumulation in lettuce grown in contaminated soils can be significantly reduced by the addition of humic substances.

  6. Ultrafast energy transfer from rigid, branched side-chains into a conjugated, alternating copolymer

    SciTech Connect

    Griffin, Graham B.; Rolczynski, Brian S.; Linkin, Alexander; McGillicuddy, Ryan D.; Engel, Gregory S.; Lundin, Pamela M.; Bao, Zhenan

    2014-01-21

    We present the synthesis and characterization of a benzodithiophene/thiophene alternating copolymer decorated with rigid, singly branched pendant side chains. We characterize exciton migration and recombination dynamics in these molecules in tetrahydrofuran solution, using a combination of static and time-resolved spectroscopies. As control experiments, we also measure electronic relaxation dynamics in isolated molecular analogues of both the side chain and polymer moieties. We employ semi-empirical and time-dependent density functional theory calculations to show that photoexcitation of the decorated copolymer using 395 nm laser pulses results in excited states primarily localized on the pendant side chains. We use ultrafast transient absorption spectroscopy to show that excitations are transferred to the polymer backbone faster than the instrumental response function, ∼250 fs.

  7. Spin-state transfer in laterally coupled quantum-dot chains with disorders

    NASA Astrophysics Data System (ADS)

    Yang, Song; Bayat, Abolfazl; Bose, Sougato

    2010-08-01

    Quantum dot arrays are a promising medium for transferring quantum information between two distant points without resorting to mobile qubits. Here we study the two most common disorders, namely hyperfine interaction and exchange coupling fluctuations, in quantum dot arrays and their effects on quantum communication through these chains. Our results show that the hyperfine interaction is more destructive than the exchange coupling fluctuations. The average optimal time for communication is not affected by any disorder in the system and our simulations show that antiferromagnetic chains are much more resistive than the ferromagnetic ones against both kind of disorders. Even when time modulation of a coupling and optimal control is employed to improve the transmission, the antiferromagnetic chain performs much better. We have assumed the quasistatic approximation for hyperfine interaction and time-dependent fluctuations in the exchange couplings. Particularly for studying exchange coupling fluctuations we have considered the static disorder, white noise, and 1/f noise.

  8. Dissemination of CERN's Technology Transfer: Added Value from Regional Transfer Agents

    ERIC Educational Resources Information Center

    Hofer, Franz

    2005-01-01

    Technologies developed at CERN, the European Organization for Nuclear Research, are disseminated via a network of external technology transfer officers. Each of CERN's 20 member states has appointed at least one technology transfer officer to help establish links with CERN. This network has been in place since 2001 and early experiences indicate…

  9. Palladium(II)-catalyzed copolymerization of styrenes with carbon monoxide: mechanism of chain propagation and chain transfer.

    PubMed

    Rix, Francis C; Rachita, Michael J; Wagner, Mark I; Brookhart, Maurice; Milani, Barbara; Barborak, James C

    2009-11-01

    A mechanistic interpretation of the [(1,10-phenanthroline)Pd(CH(3))(CH(3)CN)](+)[BArF](-) (1a) and [(2,2'-bipyridine)Pd(CH(3))(CH(3)CN)](+)[BArF](-) (1b) (BArF = 3,5-(CF(3))(2)-C(6)H(3)) catalyzed perfectly alternating copolymerization of styrenes with CO is reported. The copolymerization in CH(2)Cl(2) or chlorobenzene has been found to be first order in styrene and inverse first order in CO concentrations. The microscopic steps involved in the catalytic cycle have been studied via low temperature NMR techniques. Palladium alkyl chelate complex [(2,2'-bipyridine)Pd(CHArCH(2)C(O)CH(3)](+)[BArF](-) (5b sigma) and [(2,2'-bipyridine)Pd(eta(3)-CH(CH(2)C(O)CH(3))Ar)](+)[BArF](-) (5b pi), existing in equilibrium, were prepared. Treatment of 5b sigma,pi with (13)CO followed by 4-tert-butylstyrene at -78 degrees C allowed for (13)C NMR monitoring of the alternating chain growth of a series of palladium acyl carbonyl complexes. The acyl carbonyl species, representing the catalyst resting state, is in equilibrium with a palladium acyl styrene complex. The equilibrium constant, K(4), measured between [(phen)Pd(CO)(C(O)CH(3)](+)[BArF](-) (3a) and [(phen)Pd(C(O)CH(3))-(C(6)H(5)C=CH(2))](+)[BArF](-) (8a), was determined to be 2.84 +/- 2.8 x 10(-7) at -66 degrees C. The barrier to migratory insertion in 8a was determined (DeltaG(double dagger) (-66 degrees C) = 15.6 +/- 0.1 kcal mol(-1)). From the experimentally determined kinetic and thermodynamic data for the copolymerization of styrene with CO a mechanistic model has been constructed. The ability of this model to predict catalyst turnover frequency (TOF) was used as a test of its validity. A series of para-substituted styrenes, p-XC(6)H(4)CH=CH(2) (X = -OCH(3), -CH(3), -H, -Cl), were copolymerized with CO. A Hammett treatment of TOF for the series showed that electron-donating groups increase the rate of copolymerization (rho p = -0.8). The ratio of chain transfer to chain propagation was found to increase with styrene

  10. Rapid Polymerase Chain Reaction-based Screening Assay for Bacterial Biothreat Agents

    PubMed Central

    Yang, Samuel; Rothman, Richard E.; Hardick, Justin; Kuroki, Marcos; Hardick, Andrew; Doshi, Vishal; Ramachandran, Padmini; Gaydos, Charlotte A.

    2013-01-01

    Objectives To design and evaluate a rapid polymerase chain reaction (PCR)-based assay for detecting Eubacteria and performing early screening for selected Class A biothreat bacterial pathogens. Methods The authors designed a two-step PCR-based algorithm consisting of an initial broad-based universal detection step, followed by specific pathogen identification targeted for identification of the Class A bacterial biothreat agents. A region in the bacterial 16S rRNA gene containing a highly variable sequence flanked by clusters of conserved sequences was chosen as the target for the PCR assay design. A previously described highly conserved region located within the 16S rRNA amplicon was selected as the universal probe (UniProbe, Integrated DNA Technology, Coralville, IA). Pathogen-specific TaqMan probes were designed for Bacillus anthracis, Yersinia pestis, and Francisella tularensis. Performance of the assay was assessed using genomic DNA extracted from the aforementioned biothreat-related organisms (inactivated or surrogate) and other common bacteria. Results The UniProbe detected the presence of all tested Eubacteria (31 / 31) with high analytical sensitivity. The biothreat-specific probes accurately identified organisms down to the closely related species and genus level, but were unable to discriminate between very close surrogates, such as Yersinia philomiragia and Bacillus cereus. Conclusions A simple, two-step PCR-based assay proved capable of both universal bacterial detection and identification of select Class A bacterial biothreat and biothreat-related pathogens. Although this assay requires confirmatory testing for definitive species identification, the method has great potential for use in ED-based settings for rapid diagnosis in cases of suspected Category A bacterial biothreat agents. PMID:18370996

  11. Quantum state transfer in XXZ spin chains: A measurement induced transport method

    NASA Astrophysics Data System (ADS)

    Pouyandeh, Sima; Shahbazi, Farhad

    2015-05-01

    We study the information transferring ability of a spin-1/2 XXZ Hamiltonian for two different proposals of state transfer, namely, the well-studied attaching scenario and the recently proposed measurement induced transport. The latter one has been inspired by recent achievements in optical lattice experiments for local addressability of individual atoms and their time evolution when only local rotations and measurements are available and local control of the Hamiltonian is very limited. We show that while the both scenarios performs with almost similar quality in the case of non-interacting free fermionic XX phase, the difference become more pronounced around the isotropic Heisenberg point. Our study shows that the presence of spin-flip symmetry plays a key point in the quality of state transfer and each scenario which benefits from this symmetry transfers the quantum states with higher fidelity. In fact, for even chains this symmetry exists only for the measurement induced dynamics which then gives higher transport quality and for odd chains the spin-flip symmetry is only valid for the attaching scenarios which become more superior. We also study the effect of thermal fluctuations and environmental interactions on both scenarios.

  12. A silver bullet: elemental silver as an efficient reducing agent for atom transfer radical polymerization of acrylates.

    PubMed

    Williams, Valerie A; Ribelli, Thomas G; Chmielarz, Pawel; Park, Sangwoo; Matyjaszewski, Krzysztof

    2015-02-01

    Elemental silver was used as a reducing agent in the atom transfer radical polymerization (ATRP) of acrylates. Silver wire, in conjunction with a CuBr(2)/TPMA catalyst, enabled the controlled, rapid preparation of polyacrylates with dispersity values down to Đ = 1.03. The silver wire in these reactions was reused several times in sequential reactions without a decline in performance, and the amount of copper catalyst used was reduced to 10 ppm without a large decrease in control. A poly(n-butyl acrylate)-block-poly(tert-butyl acrylate) diblock copolymer was synthesized with a molecular weight of 91 400 and Đ = 1.04, demonstrating good retention of chain-end functionality and a high degree of livingness in this ATRP system. PMID:25599253

  13. Theoretical study of chain transfer to solvent reactions of alkyl acrylates.

    PubMed

    Moghadam, Nazanin; Srinivasan, Sriraj; Grady, Michael C; Rappe, Andrew M; Soroush, Masoud

    2014-07-24

    This computational and theoretical study deals with chain transfer to solvent (CTS) reactions of methyl acrylate (MA), ethyl acrylate (EA), and n-butyl acrylate (n-BA) self-initiated homopolymerization in solvents such as butanol (polar, protic), methyl ethyl ketone (MEK) (polar, aprotic), and p-xylene (nonpolar). The results indicate that abstraction of a hydrogen atom from the methylene group next to the oxygen atom in n-butanol, from the methylene group in MEK, and from a methyl group in p-xylene by a live polymer chain are the most likely mechanisms of CTS reactions in MA, EA, and n-BA. Energy barriers and molecular geometries of reactants, products, and transition states are predicted. The sensitivity of the predictions to three hybrid functionals (B3LYP, X3LYP, and M06-2X) and three different basis sets (6-31G(d,p), 6-311G(d), and 6-311G(d,p)) is investigated. Among n-butanol, sec-butanol, and tert-butanol, tert-butanol has the highest CTS energy barrier and the lowest rate constant. Although the application of the conductor-like screening model (COSMO) does not affect the predicted CTS kinetic parameter values, the application of the polarizable continuum model (PCM) results in higher CTS energy barriers. This increase in the predicted CTS energy barriers is larger for butanol and MEK than for p-xylene. The higher rate constants of chain transfer to n-butanol reactions compared to those of chain transfer to MEK and p-xylene reactions suggest the higher CTS reactivity of n-butanol. PMID:24971646

  14. 17 CFR 240.17Ad-16 - Notice of assumption or termination of transfer agent services.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 17 Commodity and Securities Exchanges 3 2010-04-01 2010-04-01 false Notice of assumption or termination of transfer agent services. 240.17Ad-16 Section 240.17Ad-16 Commodity and Securities Exchanges SECURITIES AND EXCHANGE COMMISSION (CONTINUED) GENERAL RULES AND REGULATIONS, SECURITIES EXCHANGE ACT OF 1934 Rules and Regulations Under...

  15. 76 FR 78215 - Possession, Use, and Transfer of Select Agents and Toxins; Biennial Review; Proposed Rule

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-12-16

    ... Services (HHS) published a Notice of Proposed Rulemaking (NPRM) in the Federal Register (76 FR 61206... of Proposed Rulemaking (NPRM) in the Federal Register (76 FR 61206) requesting public comment on (1... HUMAN SERVICES 42 CFR Part 73 RIN 0920-AA34 Possession, Use, and Transfer of Select Agents and...

  16. 77 FR 71702 - Possession, Use, and Transfer of Select Agents and Toxins; Biennial Review

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-12-04

    ... correcting a final rule that appeared in the Federal Register on October 5, 2012 (77 FR 61084). The document... INFORMATION: In FR Doc. 2012-24389, published on October 5, 2012 (77 FR 61084) appearing on pages 61086 and... HUMAN SERVICES 42 CFR Part 73 RIN 0920-AA34 Possession, Use, and Transfer of Select Agents and...

  17. Numerical Problems and Agent-Based Models for a Mass Transfer Course

    ERIC Educational Resources Information Center

    Murthi, Manohar; Shea, Lonnie D.; Snurr, Randall Q.

    2009-01-01

    Problems requiring numerical solutions of differential equations or the use of agent-based modeling are presented for use in a course on mass transfer. These problems were solved using the popular technical computing language MATLABTM. Students were introduced to MATLAB via a problem with an analytical solution. A more complex problem to which no…

  18. BASE-CATALYZED DESTRUCTION OF PCBS-NEW DONORS, NEW TRANSFER AGENTS/CATALYSTS

    EPA Science Inventory

    The use of hydrogen transfer agents and catalysts to improve the base-catalyzed decomposition of polychlorinated biphenyls (PCBs) was investigated. The reaction proceeded only in the presence of base, but the rate of PCB disappearance increased with increasing amount of hydrogen ...

  19. Mucus altering agents as adjuncts for nonviral gene transfer to airway epithelium.

    PubMed

    Ferrari, S; Kitson, C; Farley, R; Steel, R; Marriott, C; Parkins, D A; Scarpa, M; Wainwright, B; Evans, M J; Colledge, W H; Geddes, D M; Alton, E W

    2001-09-01

    Nonviral vectors have been shown to be a safe and valid alternative to recombinant viruses for gene therapy of cystic fibrosis (CF). Nevertheless, gene transfer efficiency needs to be increased before clinical efficacy is likely in man. One barrier to increased efficacy is normal airway mucus. Using an ex vivo model of sheep tracheal epithelium, we show that this barrier can, in part, be overcome by treatment with the mucolytic agents, Nacystelyn or N-acetylcysteine using either a cationic lipid or a cationic polymer as the gene transfer agent. Further, in vivo application of either Nacystelyn or the anticholinergic glycopyrrolate, both clinically used agents, resulted in increased reporter gene expression in the mouse lung, but no significant correction of the bioelectric defect in CF null mice. These results, whilst unlikely to be sufficient in themselves to achieve clinically relevant gene therapy, may be a further useful step in the attainment of this goal. PMID:11571577

  20. The Oxidation of Terminal Alkenes by Permanganate: A Practical Demonstration of the Use of Phase Transfer Agents.

    ERIC Educational Resources Information Center

    Brown, Keith C.; And Others

    1982-01-01

    Use of phase transfer agents to facilitate/accelerate chemical reactions has become an established practice, particularly in organic chemistry. Describes an undergraduate laboratory procedure demonstrating the principles involved in the use of said agents. Includes student results from phase transfer assisted permanganate oxidations. (Author/JN)

  1. 17 CFR 240.17Ad-18 - Year 2000 Reports to be made by certain transfer agents.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... preparing and testing its computer systems for Year 2000 Problems; (2) Whether the plans of the transfer agent exist in writing and address all mission critical computer systems of the transfer agent wherever... in the event that, after December 31, 1999, it has computer problems caused by Year 2000...

  2. Side-chain amino-acid-based pH-responsive self-assembled block copolymers for drug delivery and gene transfer.

    PubMed

    Kumar, Sonu; Acharya, Rituparna; Chatterji, Urmi; De, Priyadarsi

    2013-12-10

    Developing safe and effective nanocarriers for multitype of delivery system is advantageous for several kinds of successful biomedicinal therapy with the same carrier. In the present study, we have designed amino acid biomolecules derived hybrid block copolymers which can act as a promising vehicle for both drug delivery and gene transfer. Two representative natural chiral amino acid-containing (l-phenylalanine and l-alanine) vinyl monomers were polymerized via reversible addition-fragmentation chain transfer (RAFT) process in the presence of monomethoxy poly(ethylene glycol) based macro-chain transfer agents (mPEGn-CTA) for the synthesis of well-defined side-chain amino-acid-based amphiphilic block copolymers, monomethoxy poly(ethylene glycol)-b-poly(Boc-amino acid methacryloyloxyethyl ester) (mPEGn-b-P(Boc-AA-EMA)). The self-assembled micellar aggregation of these amphiphilic block copolymers were studied by fluorescence spectroscopy, atomic force microscopy (AFM) and scanning electron microscopy (SEM). Potential applications of these hybrid polymers as drug carrier have been demonstrated in vitro by encapsulation of nile red dye or doxorubicin drug into the core of the micellar nanoaggregates. Deprotection of side-chain Boc- groups in the amphiphilic block copolymers subsequently transformed them into double hydrophilic pH-responsive cationic block copolymers having primary amino groups in the side-chain terminal. The DNA binding ability of these cationic block copolymers were further investigated by using agarose gel retardation assay and AFM. The in vitro cytotoxicity assay demonstrated their biocompatible nature and these polymers can serve as "smart" materials for promising bioapplications. PMID:24274731

  3. Discovering Abstract Concepts to Aid Cross-Map Transfer for a Learning Agent

    NASA Astrophysics Data System (ADS)

    Herpson, Cédric; Corruble, Vincent

    The capacity to apply knowledge in a context different than the one in which it was learned has become crucial within the area of autonomous agents. This paper specifically addresses the issue of transfer of knowledge acquired through online learning in partially observable environments. We investigate the discovery of relevant abstract concepts which help the transfer of knowledge in the context of an environment characterized by its 2D geographical configuration. The architecture proposed is tested in a simple grid-world environment where two agents duel each other. Results show that an agent’s performances are improved through learning, including when it is tested on a map it has not yet seen.

  4. Ballistic quantum state transfer in spin chains: General theory for quasi-free models and arbitrary initial states

    NASA Astrophysics Data System (ADS)

    Banchi, Leonardo

    2013-11-01

    Ballistic quantum information transfer through spin chains is based on the idea of making the spin dynamics ruled by collective excitations with linear dispersion relation. Unlike perfect state transfer schemes, a ballistic transmission requires only a minimal engineering of the interactions; in fact, for most practical purposes, the optimization of the couplings to the ends of the chain is sufficient to obtain an almost perfect transmission. In this work we review different ballistic quantum state transfer protocols based on the dynamics of quasi-free spin chains, and further generalize them both at zero and finite temperature. In particular, besides presenting novel analytical results for XX, XY, and Ising spin models, it is shown how, via a complete control on the first and last two qubits of the chain, destructive thermal effects can be cancelled, leading to a high-quality state transmission irrespective of the temperature.

  5. Carrier transfer in vertically stacked quantum ring-quantum dot chains

    SciTech Connect

    Mazur, Yu. I. Dorogan, V. G.; Benamara, M.; Salamo, G. J.; Lopes-Oliveira, V.; Lopez-Richard, V.; Teodoro, M. D.; Marques, G. E.; Souza, L. D. de; Wu, J.; Wang, Z. M.; Tarasov, G. G.; Marega, E.

    2015-04-21

    The interplay between structural properties and charge transfer in self-assembled quantum ring (QR) chains grown by molecular beam epitaxy on top of an InGaAs/GaAs quantum dot (QD) superlattice template is analyzed and characterized. The QDs and QRs are vertically stacked and laterally coupled as well as aligned within each layer due to the strain field distributions that governs the ordering. The strong interdot coupling influences the carrier transfer both along as well as between chains in the ring layer and dot template structures. A qualitative contrast between different dynamic models has been developed. By combining temperature and excitation intensity effects, the tuning of the photoluminescence gain for either the QR or the QD mode is attained. The information obtained here about relaxation parameters, energy scheme, interlayer and interdot coupling resulting in creation of 1D structures is very important for the usage of such specific QR–QD systems for applied purposes such as lasing, detection, and energy-harvesting technology of future solar panels.

  6. Metabolic transistor strategy for controlling electron transfer chain activity in Escherichia coli

    PubMed Central

    Wu, Hui; Tuli, Leepika; Bennett, George N.; San, Ka-Yiu

    2015-01-01

    A novel strategy to finely control a large metabolic flux by using a “metabolic transistor” approach was established. In this approach a small change in the level or availability of an essential component for the process is controlled by adding a competitive reaction that affects a precursor or an intermediate in its biosynthetic pathway. The change of the basal level of the essential component, considered as a base current in a transistor, has a large effect on the flux through the major pathway. In this way, the fine-tuning of a large flux can be accomplished. The “metabolic transistor” strategy was applied to controlling electron transfer chain function by manipulation of the quinone synthesis pathway in Escherichia coli. The achievement of a theoretical yield of lactate production under aerobic conditions via this strategy upon manipulation of the biosynthetic pathway of the key participant, ubiquinone-8 (Q8), in an E. coli strain provides an in vivo, genetically tunable means to control the activity of the electron transfer chain and manipulate the production of reduced products while limiting consumption of oxygen to a defined amount. PMID:25596510

  7. Impairment of electron transfer chain induced by acute carnosine administration in skeletal muscle of young rats.

    PubMed

    Macarini, José Roberto; Maravai, Soliany Grassi; Cararo, José Henrique; Dimer, Nádia Webber; Gonçalves, Cinara Ludvig; Kist, Luiza Wilges; Bogo, Mauricio Reis; Schuck, Patrícia Fernanda; Streck, Emilio Luiz; Ferreira, Gustavo Costa

    2014-01-01

    Serum carnosinase deficiency is an inherited disorder that leads to an accumulation of carnosine in the brain tissue, cerebrospinal fluid, skeletal muscle, and other tissues of affected patients. Considering that high levels of carnosine are associated with neurological dysfunction and that the pathophysiological mechanisms involved in serum carnosinase deficiency remain poorly understood, we investigated the in vivo effects of carnosine on bioenergetics parameters, namely, respiratory chain complexes (I-III, II, and II-III), malate dehydrogenase, succinate dehydrogenase, and creatine kinase activities and the expression of mitochondrial-specific transcription factors (NRF-1, PGC-1α , and TFAM) in skeletal muscle of young Wistar rats. We observed a significant decrease of complexes I-III and II activities in animals receiving carnosine acutely, as compared to control group. However, no significant alterations in respiratory chain complexes, citric acid cycle enzymes, and creatine kinase activities were found between rats receiving carnosine chronically and control group animals. As compared to control group, mRNA levels of NRF-1, PGC-1α , and TFAM were unchanged. The present findings indicate that electron transfer through the respiratory chain is impaired in skeletal muscle of rats receiving carnosine acutely. In case these findings are confirmed by further studies and ATP depletion is also observed, impairment of bioenergetics could be considered a putative mechanism responsible for the muscle damage observed in serum carnosinase-deficient patients. PMID:24877122

  8. Impairment of Electron Transfer Chain Induced by Acute Carnosine Administration in Skeletal Muscle of Young Rats

    PubMed Central

    Macarini, José Roberto; Maravai, Soliany Grassi; Cararo, José Henrique; Dimer, Nádia Webber; Gonçalves, Cinara Ludvig; Kist, Luiza Wilges; Bogo, Mauricio Reis; Schuck, Patrícia Fernanda; Streck, Emilio Luiz; Ferreira, Gustavo Costa

    2014-01-01

    Serum carnosinase deficiency is an inherited disorder that leads to an accumulation of carnosine in the brain tissue, cerebrospinal fluid, skeletal muscle, and other tissues of affected patients. Considering that high levels of carnosine are associated with neurological dysfunction and that the pathophysiological mechanisms involved in serum carnosinase deficiency remain poorly understood, we investigated the in vivo effects of carnosine on bioenergetics parameters, namely, respiratory chain complexes (I–III, II, and II-III), malate dehydrogenase, succinate dehydrogenase, and creatine kinase activities and the expression of mitochondrial-specific transcription factors (NRF-1, PGC-1α, and TFAM) in skeletal muscle of young Wistar rats. We observed a significant decrease of complexes I–III and II activities in animals receiving carnosine acutely, as compared to control group. However, no significant alterations in respiratory chain complexes, citric acid cycle enzymes, and creatine kinase activities were found between rats receiving carnosine chronically and control group animals. As compared to control group, mRNA levels of NRF-1, PGC-1α, and TFAM were unchanged. The present findings indicate that electron transfer through the respiratory chain is impaired in skeletal muscle of rats receiving carnosine acutely. In case these findings are confirmed by further studies and ATP depletion is also observed, impairment of bioenergetics could be considered a putative mechanism responsible for the muscle damage observed in serum carnosinase-deficient patients. PMID:24877122

  9. High-throughput screening of chemical exchange saturation transfer MR contrast agents.

    PubMed

    Liu, Guanshu; Gilad, Assaf A; Bulte, Jeff W M; van Zijl, Peter C M; McMahon, Michael T

    2010-01-01

    A new high-throughput MRI method for screening chemical exchange saturation transfer (CEST) agents is demonstrated, allowing simultaneous testing of multiple samples with minimal attention to sample configuration and shimming of the main magnetic field (B(0)). This approach, which is applicable to diamagnetic, paramagnetic and liposome CEST agents, employs a set of inexpensive glass or plastic capillary tubes containing CEST agents put together in a cheap plastic tube holder, without the need for liquid between the tubes to reduce magnetic susceptibility effects. In this setup, a reference image of direct water saturation spectra is acquired in order to map the absolute water frequency for each volume element (voxel) in the sample image, followed by an image of saturation transfer spectra to determine the CEST properties. Even though the field over the total sample is very inhomogeneous due to air-tube interfaces, the shape of the direct saturation spectra is not affected, allowing removal of susceptibility shift effects from the CEST data by using the absolute water frequencies from the reference map. As a result, quantitative information such as the mean CEST intensity for each sample can be extracted for multiple CEST agents at once. As an initial application, we demonstrate rapid screening of a library of 16 polypeptides for their CEST properties, but in principle the number of tubes is limited only by the available signal-noise-ratio, field of view and gradient strength for imaging. PMID:20586030

  10. Gamma radiation induced synthesis of poly(N-isopropylacrylamide) mediated by Reversible Addition-Fragmentation Chain Transfer (RAFT) process

    NASA Astrophysics Data System (ADS)

    Kiraç, Feyza; Güven, Olgun

    2015-07-01

    Poly(N-isopropylacrylamide) (PNiPAAm) is synthesized by gamma radiation induced Reversible Addition-Fragmentation Chain Transfer (RAFT) polymerization. The monomer is polymerized in the presence of two different trithiocarbonate-based RAFT agents i.e., Cyanomethyldodecyltrithiocarbonate (CDTC) and 2-(Dodecylthiocarbonothioylthio)-2-methylpropionic acid (DMPA) in dimethylformamide (DMF) at room temperature under nitrogen atmosphere. Number-average molecular weights (Mn) and dispersities of the polymers were determined by Size Exclusion Chromatography (SEC). Dispersities (Ɖ) of the resulting polymers are narrow, i.e., Ɖ≤1.18, indicating the occurrence of well-controlled polymerization via radiation induced RAFT process. %Conversion is determined by gravimetric method and also confirmed by Proton Nuclear Magnetic Resonance (1H-NMR) Spectroscopy. By selecting proper [Monomer]/[RAFT] ratio and controlling conversion it is possible to synthesize PNiPAAm in the molecular weight range of 2400-72400 with extremely low molecular weight distributions with the anticipation of preparing corresponding size-controlled nanogels. The phase transition of PNiPAAm with low dispersity synthesized by RAFT is sharper than PNiPAAm synthesized by free radical polymerization.

  11. Simulation of radioactive cesium transfer in the southern Fukushima coastal biota using a dynamic food chain transfer model.

    PubMed

    Tateda, Yutaka; Tsumune, Daisuke; Tsubono, Takaki

    2013-10-01

    The Fukushima Dai-ichi Nuclear Power Plant (1F NPP) accident occurred on 11 March 2011. The accident introduced (137)Cs into the coastal waters which was subsequently transferred to the local coastal biota thereby elevating the concentration of this radionuclide in coastal organisms. In this study, the radioactive cesium levels in coastal biota from the southern Fukushima area were simulated using a dynamic biological compartment model. The simulation derived the possible maximum radioactive cesium levels in organisms, indicating that the maximum (137)Cs concentrations in invertebrates, benthic fish and predator fish occurred during late April, late May and late July, respectively in the studied area where the source was mainly the direct leakage of (137)Cs effluent from the 1F NPP. The delay of a (137)Cs increase in fish was explained by the gradual food chain transfer of (137)Cs introduced to the ecosystem from the initial contamination of the seawater. The model also provided the degree of radionuclide depuration in organisms, and it demonstrated the latest start of the decontamination phase in benthic fish. The ecological half-lives, derived both from model simulation and observation, were 1-4 months in invertebrates, and 2-9 months in plankton feeding fish and coastal predator fish from the studied area. In contrast, it was not possible to similarly calculate these parameters in benthic fish because of an unidentified additional radionuclide source which was deduced from the biological compartment model. To adequately reconstruct the in-situ depuration of radiocesium in benthic fish in the natural ecosystem, a contamination source associated with the bottom sediments is necessary. PMID:23639689

  12. The Potential of Poly[N-(2-hydroxypropyl)methacrylamide] via Reversible Addition-Fragmentation Chain Transfer Polymerization as Safe Nanocarrier.

    PubMed

    Zhang, Yanhong; Guo, Chunhua; Li, Shuo; Luo, Kui; Hu, Jiani; Gu, Zhongwei

    2016-06-01

    N-(2-hydroxypropyl)methacrylamide (HPMA) copolymers have been presented as nanoscale drug/gene delivery systems and imaging probes, and the well-defined HPMA copolymers prepared via reversible addition-fragmentation chain transfer (RAFT) polymerization promote their to clinical trials, as the significant enhanced anticancer efficacy. The biosafety is another issue associated with the carriers. In this study, we prepared the linear and branched HPMA copolymers labeled with Cy5.5 via RAFT polymerization and click chemistry, and their potential biosafety was studied. The linear copolymer was prepared via RAFT polymerization mediated by the ends-functionalized peptide chain transfer agent (peptide2CTA), resulting in well-defined and block linear HPMA copolymer with molecular weight (MW) of 98 kDa. Additionally, the branched HPMA copolymer was also prepared via RAFT polymerization. Followed by Cy5.5 labeling, the two copolymers showed negative zeta potential and their accumulation into tumor was studied by in vivo optical fluorescence imaging in the nude mice with breast tumors. The biosafety studies on in vitro cytotoxicity and hemocompatibility studies, including hemolysis tests, plasma coagulation and thromboelastography assay were carried out well, demonstrating that the linear HPMA copolymer-Cy5.5 with MW around 100 kDa and biodegradable moiety in the main chain might be utilized as safe nanoscale carrier. PMID:27427626

  13. Particle-size dependent accumulation and trophic transfer of cerium oxide through a terrestrial food chain.

    PubMed

    Hawthorne, Joseph; De la Torre Roche, Roberto; Xing, Baoshan; Newman, Lee A; Ma, Xingmao; Majumdar, Sanghamitra; Gardea-Torresdey, Jorge; White, Jason C

    2014-11-18

    The accumulation and trophic transfer of nanoparticle (NP) or bulk CeO2 through a terrestrial food chain was evaluated. Zucchini (Cucurbita pepo L.) was planted in soil with 0 or 1228 μg/g bulk or NP CeO2. After 28 d, zucchini tissue Ce content was determined by ICP-MS. Leaf tissue from each treatment was used to feed crickets (Acheta domesticus). After 14 d, crickets were analyzed for Ce content or were fed to wolf spiders (family Lycosidae). NP CeO2 significantly suppressed flower mass relative to control and bulk treatments. The Ce content of zucchini was significantly greater when exposure was in the NP form. The flowers, leaves, stems, and roots of zucchini exposed to bulk CeO2 contained 93.3, 707, 331, and 119,000 ng/g, respectively; NP-exposed plants contained 153, 1510, 479, and 567 000 ng/g, respectively. Crickets fed NP CeO2-exposed zucchini leaves contained significantly more Ce (33.6 ng/g) than did control or bulk-exposed insects (15.0-15.2 ng/g). Feces from control, bulk, and NP-exposed crickets contained Ce at 248, 393, and 1010 ng/g, respectively. Spiders that consumed crickets from control or bulk treatments contained nonquantifiable Ce; NP-exposed spiders contained Ce at 5.49 ng/g. These findings show that NP CeO2 accumulates in zucchini at greater levels than equivalent bulk materials and that this greater NP intake results in trophic transfer and possible food chain contamination. PMID:25340623

  14. Transfer of selenium from prey to predators in a simulated terrestrial food chain.

    PubMed

    Hopkins, William A; Staub, Brandon P; Baionno, Jennifer A; Jackson, Brian P; Talent, Larry G

    2005-04-01

    Little is known about the accumulation and effects of selenium in reptiles. We developed a simplified laboratory food chain where we fed commercial feed laden with seleno-D,L-methionine (30 microg/g dry mass) to crickets (Acheta domestica) for 5-7 d. Se-enriched crickets (approximately 15 microg/g Se [dry mass]) were fed to juvenile male and female lizards (Sceloporus occidentalis) for 98 d while conspecifics were fed uncontaminated crickets. Lizards fed contaminated prey accumulated Se concentrations ranging from 9.3 (in female carcass) to 14.1 (in female gonad) microg/g compared to <1.5 microg/g in tissues of controls. Female gonad concentrations approached the highest of thresholds for reproductive toxicity in oviparous vertebrates. However, we observed no consistent effect of dietary treatment on sublethal parameters or survival. Our simplified food chain proved to be an ecologically relevant method of exposing lizards to Se, and forms the foundation for future studies on maternal transfer and teratogenicity of Se. PMID:15620590

  15. Bioaccumulative and conchological assessment of heavy metal transfer in a soil-plant-snail food chain

    PubMed Central

    2012-01-01

    Background Copper (Cu), zinc (Zn), cadmium (Cd), and lead (Pb) can pose serious threats to environmental health because they tend to bioaccumulate in terrestrial ecosystems. We investigated under field conditions the transfer of these heavy metals in a soil-plant-snail food chain in Banat area, Romania. The main goal of this paper was to assess the Roman snail (Helix pomatia) usefulness in environmental monitoring as bioindicator of heavy metal accumulation. Eight sampling sites, selected by different history of heavy metal (HM) exposure, were chosen to be sampled for soil, nettle leaves, and newly matured snails. This study also aimed to identify the putative effects of HM accumulation in the environment on phenotypic variability in selected shell features, which included shell height (SH), relative shell height (RSH), and whorl number (WN). Results Significantly higher amounts of HMs were accumulated in snail hepatopancreas and not in foot. Cu, Zn, and Cd have biomagnified in the snail body, particularly in the hepatopancreas. In contrast, Pb decreased when going up into the food chain. Zn, Cd, and Pb correlated highly with each other at all levels of the investigated food chain. Zn and Pb exhibited an effective soil–plant transfer, whereas in the snail body only foot Cu concentration was correlated with that in soil. There were significant differences among sampling sites for WN, SH, and RSH when compared with reference snails. WN was strongly correlated with Cd and Pb concentrations in nettle leaves but not with Cu and Zn. SH was independent of HM concentrations in soil, snail hepatopancreas, and foot. However, SH correlated negatively with nettle leaves concentrations for each HM except Cu. In contrast, RSH correlated significantly only with Pb concentration in hepatopancreas. Conclusions The snail hepatopancreas accumulates high amounts of HMs, and therefore, this organ can function as a reliable biomarker for tracking HM bioavailability in soil. Long

  16. The role of solitons in charge and energy transfer in 1D molecular chains

    NASA Astrophysics Data System (ADS)

    Ivić , Zoran

    1998-03-01

    The idea that polarons and solitons could play the crucial role in the transport processes in biological structures, has been critically reexamined on the basis of the general theory of self-trapping phenomena. The criteria which enable one to determine conditions for the existence and stability of polarons and solitons and to determine their character, in dependence of the values of the basic physical parameters of the system, were formulated. Validity of the so-called Davydov's soliton model was discussed on the basis of these criteria. It was found that the original Davydov's proposal, based upon the idea of the soliton creation due to the single excitation (particle, vibron, etc.) self-trapping, cannot explain the intramolecular energy transfer in α-helix and acetanilide. However, Davydov theory is flexible enough to describe the single electron transfer in some systems (α-helix and acetanilide for example). In the many-particle systems, dressing effect, due to the quantum nature of phonons, may cause the creation of the bound states of the several excitons in the molecular chain. The possibility of creation of the soliton states of this type is discussed for the simple Fröhlich's one-dimensional model. The regions of the system parameter space where different mechanisms dominate the behaviour of such entities are characterized.

  17. Refined Model of Heat Transfer in Composite Bodies Reinforced with Tubes with a Liquid Heat-Transfer Agent Moving in a Developed Turbulent Regime

    NASA Astrophysics Data System (ADS)

    Yankovskii, A. P.

    2015-07-01

    The author has obtained equations describing thermal conductivity of composite bodies spatially reinforced with a system of smooth tubes in which an incompressible liquid heat-transfer agent is pumped in a developed turbulent regime. The corresponding boundary-value heat-conduction problem was formulated and its qualitative analysis was made. Specific calculations were performed for steady-state temperature fields in cylindrical concrete shells spirally reinforced with steel tubes through which a heat-transfer agent (air) is pumped. A study has been made of the influence of the reinforcement parameters and of the velocity and direction of the heat-transfer agent in the tubes and the dimensions of their cross sections on the temperature field. It has been established that variation of these characteristics enables one to substantially change the intensity of heat removal from the shells, opening up wide opportunities for efficient control of the heat transfer in them.

  18. Comparative analysis of using natural and radiogenic lead as heat-transfer agent in fast reactors

    NASA Astrophysics Data System (ADS)

    Laas, R. A.; Gizbrekht, R. V.; Komarov, P. A.; Nesterov, V. N.

    2016-06-01

    Fast reactors with lead coolant have several advantages over analogues. Performance can be further improved by replacement of natural composition lead with radiogenic one. Thus, two main issues need to be addressed: induced radioactivity in coolant and efficient neutron multiplication factor in the core will be changed and need to be estimated. To address these issues analysis of the scheme of the nuclear transformations in the lead heat-transfer agent in the process of radiation was carried out. Induced radioactivity of radiogenic and natural lead has been studied. It is shown that replacement of lead affects multiplication factor in a certain way. Application of radiogenic lead can significantly affect reactor operation.

  19. [Transfer characteristics of cadmium in soil-vegetable-insect food chain].

    PubMed

    Ding, Ping; Zhuang, Ping; Li, Zhi-An; Xia, Han-Ping; Tai, Yi-Ping; Lu, Huan-Ping

    2012-11-01

    Taking two kinds of vegetables (Brassica rapa and Amaranthus mangostanus) and one insect species (Prodenia litura) as test materials, a greenhouse pot experiment was conducted to study the transfer characteristics of cadmium (Cd) in soil-vegetable-insect food chain and the distribution patters of different Cd chemical forms in the organs of the two vegetables. With the increasing concentration of applied Cd in soil, the biomass of the two vegetables decreased significantly, while the Cd concentration in the vegetables had a significant increase. The Cd concentration in the vegetable organs decreased in the order of stem > root > leaf for A. mangostanus, and of stem > leaf > root for B. rapa. The Cd concentration in P. litura larvae also increased with the increasing concentration of Cd in soil, and the maximum Cd concentration in the P. litura larvae on B. rapa and A. mangostanus was 36.7 and 46.3 mg x kg(-1), respectively. In the feces of the larvae on B. rapa and A. mangostanus, the Cd concentration was up to 190 and 229.8 mg x kg(-1), respectively, suggesting that the most part of Cd absorbed by P. litura larvae was excreted out of their bodies via feces. In the organs of the two vegetables, NaCl-extractable Cd was the dominant Cd form (> 70%), followed by d-H2O- and ethanol-extractable Cd, while the HAc-extractable Cd (insoluble cadmium phosphate), HCl-extractable Cd (insoluble cadmium oxalate), and residual Cd only had a very low concentration. Such a present pattern of different Cd forms in vegetable organs could be conducive to the Cd transfer in the food chain. P. litura could ease Cd poison by excreting large amount of absorbed Cd via feces, and effectively restrict the transfer of Cd to next trophic level. Since B. rapa and A. mangostanus could accumulate large amount of Cd in their biomass, the two vegetables were suggested not to be planted in highly Cd-contaminated soil. PMID:23431799

  20. Evaluation of Isoprene Chain Extension from PEO Macromolecular Chain Transfer Agents for the Preparation of Dual, Invertible Block Copolymer Nanoassemblies

    PubMed Central

    Bartels, Jeremy W.; Cauët, Solène I.; Billings, Peter L.; Lin, Lily Yun; Zhu, Jiahua; Fidge, Christopher; Pochan, Darrin J.; Wooley, Karen L.

    2010-01-01

    Two RAFT-capable PEO macro-CTAs, 2 and 5 kDa, were prepared and used for the polymerization of isoprene which yielded well-defined block copolymers of varied lengths and compositions. GPC analysis of the PEO macro-CTAs and block copolymers showed remaining unreacted PEO macro-CTA. Mathematical deconvolution of the GPC chromatograms allowed for the estimation of the blocking efficiency, about 50% for the 5 kDa PEO macro-CTA and 64% for the 2 kDa CTA. Self assembly of the block copolymers in both water and decane was investigated and the resulting regular and inverse assemblies, respectively, were analyzed with DLS, AFM, and TEM to ascertain their dimensions and properties. Assembly of PEO-b-PIp block copolymers in aqueous solution resulted in well-defined micelles of varying sizes while the assembly in hydrophobic, organic solvent resulted in the formation of different morphologies including large aggregates and well-defined cylindrical and spherical structures. PMID:21399721

  1. Detection of nerve agents using proton transfer reaction mass spectrometry with ammonia as reagent gas.

    PubMed

    Ringer, Joachim M

    2013-01-01

    The chemical warfare agents (CWA) Sarin, Soman, Cyclosarin and Tabun were characterised by proton transfer mass spectrometry (PTRMS). It was found that PTRMS is a suitable technique to detect nerve agents highly sensitively, highly selectively and in near real-time. Methods were found to suppress molecule fragmentation which is significant under PTRMS hollow cathode ionisation conditions. In this context, the drift voltage (as one of the most important system parameters) was varied and ammonia was introduced as an additional chemical reagent gas. Auxiliary chemicals such as ammonia affect ionisation processes and are quite common in context with detectors for CWAs based on ion mobility spectrometry (IMS). With both, variation of drift voltage and ammonia as the reagent gas, fragmentation can be suppressed effectively. Suppression of fragmentation is crucial particularly concerning the implementation of an algorithm for automated agent identification in field applications. On the other hand, appearance of particular fragments might deliver additional information. Degradation and rearrangement products of nerve agents are not distinctive for the particular agent but for the chemical class they belong to. It was found that switching between ammonia doped and ordinary water ionisation chemistry can easily be performed within a few seconds. Making use of this effect it is possible to switch between fragment and molecular ion peak spectra. Thus, targeted fragmentation can be used to confirm identification based only on single peak detection. PTRMS turned out to be a promising technique for future CWA detectors. In terms of sensitivity, response time and selectivity (or confidence of identification, respectively) PTRMS performs as a bridging technique between IMS and GC-MS. PMID:24308198

  2. An Agent-Based Framework for Building Decision Support System in Supply Chain Management

    NASA Astrophysics Data System (ADS)

    Kazemi, A.; Fazel Zarandi, M. H.

    In this study, two scenarios are presented for solving Production-Distribution Panning Problem (PDPP) in a Decision Support System (DSS) framework. In the first scenario, a Traditional Decision Support System (TDSS) is presented for PDPP and a Genetic Algorithm (GA) is used for solving it. In the second scenario, a Multi-agent Decision Support System (MADSS) is considered for PDPP and three algorithms are used for solving it: Genetic Algorithm (GA), Tabu Search (TS) and Simulated Annealing (SA). Then an algorithm is suggested by using multi-agent system and A Teams concept. The obtained results reveal that the use of MADSS delivers better solutions to us.

  3. Trophic transfer of naturally produced brominated aromatic compounds in a Baltic Sea food chain.

    PubMed

    Dahlgren, Elin; Lindqvist, Dennis; Dahlgren, Henrik; Asplund, Lillemor; Lehtilä, Kari

    2016-02-01

    Brominated aromatic compounds (BACs) are widely distributed in the marine environment. Some of these compounds are highly toxic, such as certain hydroxylated polybrominated diphenyl ethers (OH-PBDEs). In addition to anthropogenic emissions through use of BACs as e.g. flame retardants, BACs are natural products formed by marine organisms such as algae, sponges, and cyanobacteria. Little is known of the transfer of BACs from natural producers and further up in the trophic food chain. In this study it was observed that total sum of methoxylated polybrominated diphenyl ethers (MeO-PBDEs) and OH-PBDEs increased in concentration from the filamentous red alga Ceramium tenuicorne, via Gammarus sp. and three-spined stickleback (Gasterosteus aculeatus) to perch (Perca fluviatilis). The MeO-PBDEs, which were expected to bioaccumulate, increased in concentration accordingly up to perch, where the levels suddenly dropped dramatically. The opposite pattern was observed for OH-PBDEs, where the concentration exhibited a general trend of decline up the food web, but increased in perch, indicating metabolic demethylation of MeO-PBDEs. Debromination was also indicated to occur when progressing through the food chain resulting in high levels of tetra-brominated MeO-PBDE and OH-PBDE congeners in fish, while some penta- and hexa-brominated congeners were observed to be the dominant products in the alga. As it has been shown that OH-PBDEs are potent disruptors of oxidative phosphorylation and that mixtures of different congener may act synergistically in terms of this toxic mode of action, the high levels of OH-PBDEs detected in perch in this study warrants further investigation into potential effects of these compounds on Baltic wildlife, and monitoring of their levels. PMID:26517387

  4. Biobased Fat Mimicking Molecular Structuring Agents for Medium-Chain Triglycerides (MCTs) and Other Edible Oils.

    PubMed

    Silverman, Julian R; John, George

    2015-12-01

    To develop sustainable value-added materials from biomass, novel small-molecule sugar ester gelators were synthesized using biocatalysis. The facile one-step regiospecific coupling of the pro-antioxidant raspberry ketone glucoside and unsaturated or saturated long- and medium-chain fatty acids provides a simple approach to tailor the structure and self-assembly of the amphiphilic product. These low molecular weight molecules demonstrated the ability to self-assemble in a variety of solvents and exhibited supergelation, with a minimum gelation concentration of 0.25 wt %, in numerous organic solvents, as well as in a range of natural edible oils, specifically a relatively unstudied group of liquids: natural medium-chain triglyceride oils, notably coconut oil. Spectroscopic analysis details the gelator structure as well as the intermolecular noncovalent interactions, which allow for gelation. X-ray diffraction studies indicate fatty acid chain packing of gelators is similar to that of natural fats, signifying the crystalline nature may lead to desirable textural properties and mouthfeel. PMID:26624525

  5. Physical characteristics of lanthanide complexes that act as magnetization transfer (MT) contrast agents

    NASA Astrophysics Data System (ADS)

    Zhang, Shanrong; Sherry, A. Dean

    2003-02-01

    Rapid water exchange is normally considered a prerequisite for efficient Gd 3+-based MRI contrast agents. Yet recent measures of exchange rates in some Gd 3+ complexes have shown that water exchange can become limiting when such complexes are attached to larger macromolecular structures. A new class of lanthanide complexes that display unusually slow water exchange (bound water lifetimes ( τM298) > 10 μs) has recently been reported. This apparent disadvantage may be taken advantage of by switching the metal ion from gadolinium(III) to a lanthanide that shifts the bound water resonance substantially away from bulk water. Given appropriate water exchange kinetics, one can then alter the intensity of the bulk water signal by selective presaturation of this highly shifted, Ln3+-bound water resonance. This provides the basis of a new method to alter MR image contrast in tissue. We have synthesized a variety of DOTA-tetra(amide) ligands to evaluate as potential magnetization transfer (MT) contrast agents and found that the bound water lifetimes in these complexes are sensitive to both ligand structure (a series of Eu 3+ complexes have τM298 values that range from 1 to 1300 μs) and the identity of the paramagnetic Ln3+ cation (from 3 to 800 μs for a single ligand). This demonstrates that it may be possible either to fine-tune the ligand structure or to select proper lanthanide cation to create an optimal MT agent for any clinical imaging field.

  6. STRUCTURAL ANALYSIS OF ALTERNATIVE COMPLEX III IN THE PHOTOSYNTHETIC ELECTRON TRANSFER CHAIN OF CHLOROFLEXUS AURANTIACUS

    PubMed Central

    Gao, Xinliu; Xin, Yueyong; Bell, Patrick D.; Wen, Jianzhong; Blankenship, Robert E.

    2010-01-01

    The green photosynthetic bacterium Chloroflexus aurantiacus, which belongs to the phylum of filamentous anoxygenic phototrophs, does not contain a cytochrome bc or bf type complex as is found in all other known groups of phototrophs. This suggests that a functional replacement exists to link the reaction center photochemistry to cyclic electron transfer as well as respiration. Earlier work identified a potential substitute of the cytochrome bc complex, now named alternative complex III (ACIII), which has been purified, identified and characterized from C. aurantiacus. ACIII functions as a menaquinol:auracyanin oxidoreductase in the photosynthetic electron transfer chain, and a related but distinct complex functions in respiratory electron flow to a terminal oxidase. In this work, we focus on elucidating the structure of the photosynthetic ACIII. We found that AC III is an integral-membrane protein complex of around 300 kDa that consists of 8 subunits of 7 different types. Among them, there are 4 metalloprotein subunits, including a 113 kDa iron-sulfur cluster-containing polypeptide, a 25 kDa penta-heme c-containing subunit and two 20 kDa mono-heme c-containing subunits in the form of a homodimer. A variety of analytical techniques were employed in determining the ACIII substructure, including HPLC combined with ESI-MS, metal analysis, potentiometric titration and intensity analysis of heme-staining SDS-PAGE. A preliminary structural model of the ACIII complex is proposed based on the analytical data and chemical cross-linking in tandem with mass analysis using MALDI-TOF, as well as transmembrane and transit peptide analysis. PMID:20614874

  7. The horizontal transfer of antibiotic resistance genes is enhanced by ionic liquid with different structure of varying alkyl chain length

    PubMed Central

    Wang, Qing; Lu, Qian; Mao, Daqing; Cui, Yuxiao; Luo, Yi

    2015-01-01

    Antibiotic resistance genes (ARGs) have become a global health concern. In our previous study, an ionic liquid (IL) 1-butyl-3-methylimidazolium hexafluorophosphate ([BMIm][PF6]) had been proven to facilitate the dissemination of ARGs in the environment. However, enhanced alkyl group chain length or the substitution of alkyl groups with the cation ring corresponded with increased antimicrobial effects. In this study, we investigated how different structures of ILs with 4, 6, and 8 C atoms in the longer alkyl chain on the imidazolium cations facilitated the dissemination of ARGs. The promotion of plasmid RP4 transfer frequency decreased with [CnMIM][BF4] increasing the alkyl chain length from 4 carbon atoms to 8 carbon atoms on the imidazolium cations, which is observed with [BMIM][BF4] (n = 4, 5.9 fold) > HMIM][BF4] (n = 6, 2.2 fold) > [OMIM][BF4] (n = 8, 1.7 fold). This illustrates that [CnMIM][BF4] with increasing the alkyl chain length exert decreasing ability in facilitating plasmid RP4 horizontal transfer, which is possibly related to IL-structure dependent toxicity. The IL-structure dependent plasmid RP4 transfer frequency was attributable to bacterial cell membrane permeability weaken with increasing alkyl chain length of [CnMIM][PF4], which was evidenced by flow cytometry. In freshwater microcosm, [CnMIm][BF4] promoted the relative abundance of the sulI and intI genes for 4.6 folds, aphA and traF for 5.2 folds higher than the untreated groups, promoting the propagation of ARGs in the aquatic environment. This is the first report that ILs with different structure of varying alkyl chain length facilitate horizontal transfer of plasmid RP4 which is widely distributed in the environment, and thus add the adverse effects of the environmental risk of ILs. PMID:26379641

  8. Surface protein imprinted core-shell particles for high selective lysozyme recognition prepared by reversible addition-fragmentation chain transfer strategy.

    PubMed

    Li, Qinran; Yang, Kaiguang; Liang, Yu; Jiang, Bo; Liu, Jianxi; Zhang, Lihua; Liang, Zhen; Zhang, Yukui

    2014-12-24

    A novel kind of lysozyme (Lys) surface imprinted core-shell particles was synthesized by reversible addition-fragmentation chain transfer (RAFT) strategy. With controllable polymer shell chain length, such particles showed obviously improved selectivity for protein recognition. After the RAFT initial agent and template protein was absorbed on silica particles, the prepolymerization solution, with methacrylic acid and 2-hydroxyethyl methacrylate as the monomers, and N,N'-methylenebis(acrylamide) as the cross-linker, was mixed with the silica particles, and the polymerization was performed at 40 °C in aqueous phase through the oxidation-reduction initiation. Ater polymerization, with the template protein removal and destroying dithioester groups with hexylamine, the surface Lyz imprinted particles were obtained with controllable polymer chain length. The binding capacity of the Lys imprinted particles could reach 5.6 mg protein/g material, with the imprinting factor (IF) as 3.7, whereas the IF of the control material prepared without RAFT strategy was only 1.6. The absorption equilibrium could be achieved within 60 min. Moreover, Lys could be selectively recognized by the imprinted particles from both a four-proteins mixture and egg white sample. All these results demonstrated that these particles prepared by RAFT strategy are promising to achieve the protein recognition with high selectivity. PMID:25434676

  9. THE ROLE OF THE QUINONE POOL IN THE CYCLIC ELECTRON-TRANSFER CHAIN OF RHODOPSEUDOMONAS SPHAEROIDES

    PubMed Central

    CROFTS, A.R.; MEINHARDT, S.W.; JONES, K.R.; SNOZZI, M.

    2010-01-01

    (1) The role of the ubiquinone pool in the reactions of the cyclic electron-transfer chain has been investigated by observing the effects of reduction of the ubiquinone pool on the kinetics and extent of the cytochrome and electrochromic carotenoid absorbance changes following flash illumination. (2) In the presence of antimycin, flash-induced reduction of cytochrome b-561 is dependent on a coupled oxidation of ubiquinol. The ubiquinol oxidase site of the ubiquinol:cytochrome c2 oxidoreductase catalyses a concerted reaction in which one electron is transferred to a high-potential chain containing cytochromes c1 and c2, the Rieske-type iron-sulfur center, and the reaction center primary donor, and a second electron is transferred to a low-potential chain containing cytochromes b-566 and b-561. (3) The rate of reduction of cytochrome b-561 in the presence of antimycin has been shown to reflect the rate of turnover of the ubiquinol oxidase site. This diagnostic feature has been used to measure the dependence of the kinetics of the site on the ubiquinol concentration. Over a limited range of concentration (0–3 mol ubiquinol/mol cytochrome b-561), the kinetics showed a second-order process, first order with respect to ubiquinol from the pool. At higher ubiquinol concentrations, other processes became rate determining, so that above approx. 25 mol ubiquinol/mol cytochrome b-561, no further increase in rate was seen. (4) The kinetics and extents of cytochrome b-561 reduction following a flash in the presence of antimycin, and of the antimycin-sensitive reduction of cytochrome c1 and c2, and the slow phase of the carotenoid change, have been measured as a function of redox potential over a wide range. The initial rate for all these processes increased on reduction of the suspension over the range between 180 and 100 mV (pH 7). The increase in rate occurred as the concentration of ubiquinol in the pool increased on reduction, and could be accounted for in terms of the

  10. In vitro assembly of a prohead-like structure of the Rhodobacter capsulatus gene transfer agent

    SciTech Connect

    Spano, Anthony J. . E-mail: ajs6z@virginia.edu; Chen, Frank S.; Goodman, Benjamin E.; Sabat, Agnes E.; Simon, Martha N.; Wall, Joseph S.; Correia, John J.; McIvor, Wilson; Newcomb, William W.; Brown, Jay C.; Schnur, Joel M.; Lebedev, Nikolai

    2007-07-20

    The gene transfer agent (GTA) is a phage-like particle capable of exchanging double-stranded DNA fragments between cells of the photosynthetic bacterium Rhodobacter capsulatus. Here we show that the major capsid protein of GTA, expressed in E. coli, can be assembled into prohead-like structures in the presence of calcium ions in vitro. Transmission electron microscopy (TEM) of uranyl acetate staining material and thin sections of glutaraldehyde-fixed material demonstrates that these associates have spherical structures with diameters in the range of 27-35 nm. The analysis of scanning TEM images revealed particles of mass {approx} 4.3 MDa, representing 101 {+-} 11 copies of the monomeric subunit. The establishment of this simple and rapid method to form prohead-like particles permits the GTA system to be used for genome manipulation within the photosynthetic bacterium, for specific targeted drug delivery, and for the construction of biologically based distributed autonomous sensors for environmental monitoring.

  11. In vitro assembly of a prohead-like structure of the Rhodobacter capsulatus gene transfer agent.

    PubMed

    Spano, Anthony J; Chen, Frank S; Goodman, Benjamin E; Sabat, Agnes E; Simon, Martha N; Wall, Joseph S; Correia, John J; McIvor, Wilson; Newcomb, William W; Brown, Jay C; Schnur, Joel M; Lebedev, Nikolai

    2007-07-20

    The gene transfer agent (GTA) is a phage-like particle capable of exchanging double-stranded DNA fragments between cells of the photosynthetic bacterium Rhodobacter capsulatus. Here we show that the major capsid protein of GTA, expressed in E. coli, can be assembled into prohead-like structures in the presence of calcium ions in vitro. Transmission electron microscopy (TEM) of uranyl acetate staining material and thin sections of glutaraldehyde-fixed material demonstrates that these associates have spherical structures with diameters in the range of 27-35 nm. The analysis of scanning TEM images revealed particles of mass approximately 4.3 MDa, representing 101+/-11 copies of the monomeric subunit. The establishment of this simple and rapid method to form prohead-like particles permits the GTA system to be used for genome manipulation within the photosynthetic bacterium, for specific targeted drug delivery, and for the construction of biologically based distributed autonomous sensors for environmental monitoring. PMID:17408713

  12. Origin of the red sites and energy transfer rates in single MEH-PPV chains at low temperature.

    PubMed

    Feist, Florian A; Zickler, Martin F; Basché, Thomas

    2011-06-01

    Single poly[2-methoxy-5-(2'-ethyl-hexyloxy)-1,4-phenylene vinylene] (MEH-PPV) molecules dispersed in thin poly(methylmethacrylate) films have been investigated by fluorescence emission, excitation and time-resolved spectroscopy at 1.2 K. For the molecular weight studied (∼200 kDa) a bimodal distribution of emission maxima is observed. Based on a comparison of the spectroscopic properties of blue and red sites and on polarisation-resolved measurements, we argue in agreement with recent quantum-chemical calculations that the red subpopulation most probably does not arise from interchromophoric excitation delocalisation but is to be attributed to longer chromophoric units originating from ordered regions of a polymer chain, where due to constraints on the chain conformation larger conjugation lengths can be realised. In excitation spectra within the red spectral region we can identify multiple chromophoric units, among them chromophores without correspondence in the emission spectrum-donors of the intramolecular energy transfer. Zero-phonon lines of donor chromophores proved to be significantly broadened, indicating fast excited-state population decay due to energy transfer. Thus, a distribution of energy transfer times within MEH-PPV chains could be determined from donor zero-phonon line widths, with an average value of 3.9 ps. Our study represents the first direct measurement of energy transfer times in conjugated polymers, parameters that are crucial for the performance of many technical applications based on this class of material. PMID:21472962

  13. Food-chain transfer of U-series radionuclides in a northern Saskatchewan aquatic system

    SciTech Connect

    Swanson, S.M.

    1985-11-01

    Levels of Total U, 226Ra, and 210Pb in water, sediments, insects and fish were measured in a stream and a lake affected by U mill effluents and in three uncontaminated systems (one creek and two lakes). Radionuclide levels were significantly elevated in water, sediments and biota at contaminated sites. Radionuclide concentration declined with each successive trophic level due primarily to very low assimilation efficiency. Fish radionuclide concentrations varied with season but did not vary with age or year of sampling. Distribution coefficients were high; therefore, a large proportion of radionuclides entering the systems go to the solid phase. Organisms feeding on or near sediments had higher radionuclide levels than pelagic species. There is a potential for long-term cycling of radionuclides from sediments through food chains due to low flux and sedimentation rates. With the exception of water-insects and water-fish all transfer coefficients (TC) were low, usually less than one. Control TCs were greater than TCs in contaminated areas. Radium-226 and 210Pb TCs declined dramatically at the insect-fish level. Uranium uptake from water by insects and fish was much less than 226Ra or 210Pb uptake. Uptake from sediments was similar for all nuclides in insects but 210Pb sediment-fish TCs differed from 226Ra or U TCs. The critical pathway in the contaminated area was sediments-insects-forage fish-whitefish-man. Estimated internal dose rates to large fish in the contaminated area were 1-2 rad/y. Dose to humans from consumption of one fish serving per week for 1 y was 2% of the International Commission on Radiological Protection (ICRP) annual limit for the general public.

  14. In vivo visual evaluation of nanoparticle transfer in a three-species terrestrial food chain.

    PubMed

    Chae, Yooeun; Kim, Shin Woong; An, Youn-Joo

    2016-05-01

    Nanoparticles (NPs) are increasingly being used, and they present the risk of being introduced into food webs. Numerous studies have been conducted to evaluate the toxicological effects of NPs in the aquatic and freshwater environments and their transfer to upper-level trophic organisms. However, information on the transfer and consequent effects of NPs on soil invertebrates is still limited. In this study, we assessed the transfer of quantum dots (QDs) through a three-species terrestrial food chain that consisted of the yeast Saccharomyces cerevisiae, the collembolan Folsomia candida, and the pill bug Armadillidium vulgare, as well as their biodistribution in vital organs using fluorescence analytical techniques. To visualize QD incorporation and biodistribution in F. candida, longitudinal and transversal sections were observed after short-term (3 d) and long-term (12 d) feeding with QD-treated yeast. QDs were located only in the intestine of F. candida and excreted within 1-2 d. QDs were also transferred to the pill bug by feeding, and remained in its intestine. This study showed the transfer of NPs through a model terrestrial food chain and indicated the potential hazards of released NPs for organisms at different trophic levels. PMID:26933900

  15. Effect of the alkyl chain length of secondary amines on the phase transfer of gold nanoparticles from water to toluene.

    PubMed

    Soliwoda, Katarzyna; Tomaszewska, Emilia; Tkacz-Szczesna, Beata; Mackiewicz, Ewelina; Rosowski, Marcin; Bald, Adam; Blanck, Christian; Schmutz, Marc; Novák, Jiří; Schreiber, Frank; Celichowski, Grzegorz; Grobelny, Jaroslaw

    2014-06-17

    In the present paper we describe a phase transfer of aqueous synthesized gold nanoparticles (AuNPs) from water to toluene using secondary amines: dioctylamine, didodecylamine, and dioctadecylamine. The effect of the hydrocarbon chain length and amount of amines on the transfer efficiency were investigated in the case of nanoparticles (NPs) with three different sizes: 5, 9, and 13 nm. Aqueous colloids were precisely characterized before the transfer process using UV-vis spectroscopy, dynamic light scattering (DLS), small-angle X-ray scattering (SAXS), and transmission electron microscopy (TEM). Nanoparticles were next transferred to toluene and characterized using UV-vis and DLS techniques. It was found that dioctadecylamine provides the most effective transfer of nanoparticles. No time-dependent changes in the NP size were observed after 12 days, showing that the dioctadecylamine-stabilized nanoparticles dispersed in toluene were stable. This indicates that long hydrocarbon chains of dioctadecylamine exhibit sufficiently hydrophobic properties of nanoparticles and consequently their good dispersibility in nonpolar solvent. PMID:24893068

  16. [Experimental study of vibrio parahaemolyticus (biotype 2) transfer from water and sediments to benthic marine food chain organisms].

    PubMed

    Gauthier, M J; Clement, R

    1979-04-01

    Transfer of Vibrio parahaemolyticus (biotype 2) from sediments to water and from water to benthic marine organisms was studied experimentally using a streptomycin-resistant strain. Transmission by trophic pathways was also studied using reconstituted marine food chains (Mytilus edulis, Nereis diversicolor, Carcinus maenas, Scorpaena porcus, Mus musculus). Water colonization by sediments could be observed only at temperatures above 16 degrees C. Sediments could well constitute a disseminating reservoir for these germs, their cycle in water being dependent of the cycle followed in the sediments. Contamination of animal organisms is essentially effected by a direct mean, either water or sediments; transfer by trophic pathways being negligible. Infection of land consumers (mice) is linked quantitatively to the nature of the last marine organism of the food chain since bacteria can flourish in the digestive tract of certain animals (Carcinus maenas). PMID:487292

  17. 17 CFR 240.17Ad-18 - Year 2000 Reports to be made by certain transfer agents.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... approved and funded plans for preparing and testing its computer systems for Year 2000 Problems; (2) Whether the plans of the transfer agent exist in writing and address all mission critical computer systems... in the event that, after December 31, 1999, it has computer problems caused by Year 2000...

  18. 12 CFR 709.10 - Treatment by conservator or liquidating agent of financial assets transferred in connection with...

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 12 Banks and Banking 6 2010-01-01 2010-01-01 false Treatment by conservator or liquidating agent of financial assets transferred in connection with a securitization or participation. 709.10 Section 709.10 Banks and Banking NATIONAL CREDIT UNION ADMINISTRATION REGULATIONS AFFECTING CREDIT UNIONS INVOLUNTARY LIQUIDATION OF FEDERAL CREDIT UNIONS...

  19. Identification of a Divided Genome for VSH-1, the Prophage-Like Gene Transfer Agent of Brachyspira hyodysenteriae

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The Brachyspira hyodysenteriae B204 genome sequence revealed three VSH-1 tail genes hvp31, hvp60, and hvp37, in a 3.6 kb cluster. The location and transcription direction of these genes relative to the previously described VSH-1 16.3 kb gene operon indicate that the gene transfer agent VSH-1 has a ...

  20. 17 CFR 249b.101 - Form TA-W, notice of withdrawal from registration as transfer agent.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ...))) Editorial Note: For Federal Register citations affecting Form TA-W, see the List of CFR Sections Affected... 17 Commodity and Securities Exchanges 4 2014-04-01 2014-04-01 false Form TA-W, notice of... TA-W, notice of withdrawal from registration as transfer agent. This form shall be used...

  1. 17 CFR 249b.101 - Form TA-W, notice of withdrawal from registration as transfer agent.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ...))) Editorial Note: For Federal Register citations affecting Form TA-W, see the List of CFR Sections Affected... 17 Commodity and Securities Exchanges 3 2012-04-01 2012-04-01 false Form TA-W, notice of... TA-W, notice of withdrawal from registration as transfer agent. This form shall be used...

  2. 17 CFR 249b.101 - Form TA-W, notice of withdrawal from registration as transfer agent.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ...))) Editorial Note: For Federal Register citations affecting Form TA-W, see the List of CFR Sections Affected... 17 Commodity and Securities Exchanges 3 2011-04-01 2011-04-01 false Form TA-W, notice of... TA-W, notice of withdrawal from registration as transfer agent. This form shall be used...

  3. 17 CFR 249b.101 - Form TA-W, notice of withdrawal from registration as transfer agent.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ...))) Editorial Note: For Federal Register citations affecting Form TA-W, see the List of CFR Sections Affected... 17 Commodity and Securities Exchanges 3 2010-04-01 2010-04-01 false Form TA-W, notice of... TA-W, notice of withdrawal from registration as transfer agent. This form shall be used...

  4. 17 CFR 249b.101 - Form TA-W, notice of withdrawal from registration as transfer agent.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ...))) Editorial Note: For Federal Register citations affecting Form TA-W, see the List of CFR Sections Affected... 17 Commodity and Securities Exchanges 3 2013-04-01 2013-04-01 false Form TA-W, notice of... TA-W, notice of withdrawal from registration as transfer agent. This form shall be used...

  5. Dynamic protein conformations preferentially drive energy transfer along the active chain of the photosystem II reaction centre.

    PubMed

    Zhang, Lu; Silva, Daniel-Adriano; Zhang, Houdao; Yue, Alexander; Yan, YiJing; Huang, Xuhui

    2014-01-01

    One longstanding puzzle concerning photosystem II, a core component of photosynthesis, is that only one of the two symmetric branches in its reaction centre is active in electron transfer. To investigate the effect of the photosystem II environment on the preferential selection of the energy transfer pathway (a prerequisite for electron transfer), we have constructed an exciton model via extensive molecular dynamics simulations and quantum mechanics/molecular mechanics calculations based on a recent X-ray structure. Our results suggest that it is essential to take into account an ensemble of protein conformations to accurately compute the site energies. We identify the cofactor CLA606 of active chain as the most probable site for the energy excitation. We further pinpoint a number of charged protein residues that collectively lower the CLA606 site energy. Our work provides insights into the understanding of molecular mechanisms of the core machinery of the green-plant photosynthesis. PMID:24954746

  6. Emulating quantum state transfer through a spin-1 chain on a one-dimensional lattice of superconducting qutrits

    NASA Astrophysics Data System (ADS)

    Ghosh, Joydip

    2014-12-01

    Spin-1 systems, in comparison to spin-1/2 systems, offer a better security for encoding and transferring quantum information, primarily due to their larger Hilbert spaces. Superconducting artificial atoms possess multiple energy levels, thereby being capable of emulating higher-spin systems. Here I consider a one-dimensional lattice of nearest-neighbor-coupled superconducting transmon systems, and devise a scheme to transfer an arbitrary qutrit state (a state encoded in a three-level quantum system) across the chain. I assume adjustable couplings between adjacent transmons, derive an analytic constraint for the control pulse, and show how to satisfy the constraint to achieve a high-fidelity state transfer under current experimental conditions. My protocol thus enables enhanced quantum communication and information processing with promising superconducting qutrits.

  7. Genetic Diversity of Bacterial Communities and Gene Transfer Agents in Northern South China Sea

    PubMed Central

    Sun, Fu-Lin; Wang, You-Shao; Wu, Mei-Lin; Jiang, Zhao-Yu; Sun, Cui-Ci; Cheng, Hao

    2014-01-01

    Pyrosequencing of the 16S ribosomal RNA gene (rDNA) amplicons was performed to investigate the unique distribution of bacterial communities in northern South China Sea (nSCS) and evaluate community structure and spatial differences of bacterial diversity. Cyanobacteria, Proteobacteria, Actinobacteria, and Bacteroidetes constitute the majority of bacteria. The taxonomic description of bacterial communities revealed that more Chroococcales, SAR11 clade, Acidimicrobiales, Rhodobacterales, and Flavobacteriales are present in the nSCS waters than other bacterial groups. Rhodobacterales were less abundant in tropical water (nSCS) than in temperate and cold waters. Furthermore, the diversity of Rhodobacterales based on the gene transfer agent (GTA) major capsid gene (g5) was investigated. Four g5 gene clone libraries were constructed from samples representing different regions and yielded diverse sequences. Fourteen g5 clusters could be identified among 197 nSCS clones. These clusters were also related to known g5 sequences derived from genome-sequenced Rhodobacterales. The composition of g5 sequences in surface water varied with the g5 sequences in the sampling sites; this result indicated that the Rhodobacterales population could be highly diverse in nSCS. Phylogenetic tree analysis result indicated distinguishable diversity patterns among tropical (nSCS), temperate, and cold waters, thereby supporting the niche adaptation of specific Rhodobacterales members in unique environments. PMID:25364820

  8. A novel roseobacter phage possesses features of podoviruses, siphoviruses, prophages and gene transfer agents.

    PubMed

    Zhan, Yuanchao; Huang, Sijun; Voget, Sonja; Simon, Meinhard; Chen, Feng

    2016-01-01

    Bacteria in the Roseobacter lineage have been studied extensively due to their significant biogeochemical roles in the marine ecosystem. However, our knowledge on bacteriophage which infects the Roseobacter clade is still very limited. Here, we report a new bacteriophage, phage DSS3Φ8, which infects marine roseobacter Ruegeria pomeroyi DSS-3. DSS3Φ8 is a lytic siphovirus. Genomic analysis showed that DSS3Φ8 is most closely related to a group of siphoviruses, CbK-like phages, which infect freshwater bacterium Caulobacter crescentus. DSS3Φ8 contains a smaller capsid and has a reduced genome size (146 kb) compared to the CbK-like phages (205-279 kb). DSS3Φ8 contains the DNA polymerase gene which is closely related to T7-like podoviruses. DSS3Φ8 also contains the integrase and repressor genes, indicating its potential to involve in lysogenic cycle. In addition, four GTA (gene transfer agent) genes were identified in the DSS3Φ8 genome. Genomic analysis suggests that DSS3Φ8 is a highly mosaic phage that inherits the genetic features from siphoviruses, podoviruses, prophages and GTAs. This is the first report of CbK-like phages infecting marine bacteria. We believe phage isolation is still a powerful tool that can lead to discovery of new phages and help interpret the overwhelming unknown sequences in the viral metagenomics. PMID:27460944

  9. A novel roseobacter phage possesses features of podoviruses, siphoviruses, prophages and gene transfer agents

    NASA Astrophysics Data System (ADS)

    Zhan, Yuanchao; Huang, Sijun; Voget, Sonja; Simon, Meinhard; Chen, Feng

    2016-07-01

    Bacteria in the Roseobacter lineage have been studied extensively due to their significant biogeochemical roles in the marine ecosystem. However, our knowledge on bacteriophage which infects the Roseobacter clade is still very limited. Here, we report a new bacteriophage, phage DSS3Φ8, which infects marine roseobacter Ruegeria pomeroyi DSS-3. DSS3Φ8 is a lytic siphovirus. Genomic analysis showed that DSS3Φ8 is most closely related to a group of siphoviruses, CbK-like phages, which infect freshwater bacterium Caulobacter crescentus. DSS3Φ8 contains a smaller capsid and has a reduced genome size (146 kb) compared to the CbK-like phages (205–279 kb). DSS3Φ8 contains the DNA polymerase gene which is closely related to T7-like podoviruses. DSS3Φ8 also contains the integrase and repressor genes, indicating its potential to involve in lysogenic cycle. In addition, four GTA (gene transfer agent) genes were identified in the DSS3Φ8 genome. Genomic analysis suggests that DSS3Φ8 is a highly mosaic phage that inherits the genetic features from siphoviruses, podoviruses, prophages and GTAs. This is the first report of CbK-like phages infecting marine bacteria. We believe phage isolation is still a powerful tool that can lead to discovery of new phages and help interpret the overwhelming unknown sequences in the viral metagenomics.

  10. A novel roseobacter phage possesses features of podoviruses, siphoviruses, prophages and gene transfer agents

    PubMed Central

    Zhan, Yuanchao; Huang, Sijun; Voget, Sonja; Simon, Meinhard; Chen, Feng

    2016-01-01

    Bacteria in the Roseobacter lineage have been studied extensively due to their significant biogeochemical roles in the marine ecosystem. However, our knowledge on bacteriophage which infects the Roseobacter clade is still very limited. Here, we report a new bacteriophage, phage DSS3Φ8, which infects marine roseobacter Ruegeria pomeroyi DSS-3. DSS3Φ8 is a lytic siphovirus. Genomic analysis showed that DSS3Φ8 is most closely related to a group of siphoviruses, CbK-like phages, which infect freshwater bacterium Caulobacter crescentus. DSS3Φ8 contains a smaller capsid and has a reduced genome size (146 kb) compared to the CbK-like phages (205–279 kb). DSS3Φ8 contains the DNA polymerase gene which is closely related to T7-like podoviruses. DSS3Φ8 also contains the integrase and repressor genes, indicating its potential to involve in lysogenic cycle. In addition, four GTA (gene transfer agent) genes were identified in the DSS3Φ8 genome. Genomic analysis suggests that DSS3Φ8 is a highly mosaic phage that inherits the genetic features from siphoviruses, podoviruses, prophages and GTAs. This is the first report of CbK-like phages infecting marine bacteria. We believe phage isolation is still a powerful tool that can lead to discovery of new phages and help interpret the overwhelming unknown sequences in the viral metagenomics. PMID:27460944

  11. 75 FR 68012 - Notice of Intention To Cancel Registrations of Certain Transfer Agents

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-11-04

    .... Advest Transfer Services, Inc 8405855 AGN Associates & Stock Transfer Services, LLC 8406255 Amazon Natural Treasures.com , Inc 8405839 Beverly National Corporation 8505474 Capital Fund Services,...

  12. Synthesis of magnetic molecularly imprinted polymers by reversible addition fragmentation chain transfer strategy and its application in the Sudan dyes residue analysis.

    PubMed

    Xie, Xiaoyu; Chen, Liang; Pan, Xiaoyan; Wang, Sicen

    2015-07-31

    Magnetic molecularly imprinted polymers (MMIPs) have become a hotspot owing to the dual functions of target recognition and magnetic separation. In this study, the MMIPs were obtained by the surface-initiated reversible addition fragmentation chain transfer (RAFT) polymerization using Sudan I as the template. The resultant MMIPs were characterized by transmission electron microscope, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, vibrating sample magnetometer, and X-ray diffraction. Benefiting from the controlled/living property of the RAFT strategy, the uniform MIP layer was successfully grafted on the surface of RAFT agent-modified Fe3O4@SiO2 nanoparticles, favoring the fast mass transfer and rapid binding kinetics. The developed MMIPs were used as the solid-phase extraction sorbents to selectively extract four Sudan dyes (Sudan I, II, III, and IV) from chili powder samples. The recoveries of the spiked samples in chili powder samples ranged from 74.1 to 93.3% with RSD lower than 6.4% and the relative standard uncertainty lower than 0.029. This work provided a good platform for the extraction and removal of Sudan dyes in complicated matrixes and demonstrated a bright future for the application of the well-constructed MMIPs in the field of solid-phase extraction. PMID:26077971

  13. Antibody-Directed Cytotoxic Agents: Use of Monoclonal Antibody to Direct the Action of Toxin A Chains to Colorectal Carcinoma Cells

    NASA Astrophysics Data System (ADS)

    Gilliland, D. Gary; Steplewski, Zenon; Collier, R. John; Mitchell, Kenneth F.; Chang, Tong H.; Koprowski, Hilary

    1980-08-01

    We have constructed cell-specific cytotoxic agents by covalently coupling the A chain from diphtheria toxin or ricin toxin to monoclonal antibody directed against a colorectal carcinoma tumor-associated antigen. Antibody 1083-17-1A was modified by attachment of 3-(2-pyridyldithio)propionyl or cystaminyl groups and then treated with reduced A chain to give disulfide-linked conjugates that retained the original binding specificity of the antibody moiety. The conjugates showed cytotoxic activity for colorectal carcinoma cells in culture, but were not toxic in the same concentration range for a variety of cell lines that lacked the antigen. Under defined conditions virtually 100% of antigen-bearing cultured cells were killed, whereas cells that lacked the antigen were not affected. Conjugates containing toxin A chains coupled to monoclonal antibodies may be useful in studying functions of various cell surface components and, possibly, as tumor-specific therapeutic agents.

  14. Terrestrial model food chain and environmental chemicals. I. Transfer of sodium [14C]pentachlorophenate between springtails and carabids.

    PubMed

    Gruttke, H; Kratz, W; Weigmann, G; Haque, A

    1988-06-01

    A model soil food chain of a ruderal ecosystem has been constructed in order to study the uptake, transfer, and accumulation of [14C]pentachlorophenate (PCP-Na). The model was based on three food levels, viz. baker's yeast, collembola, and carabid beetles, and the contaminant chemical introduced was via initial food. Continuous exposure of the organisms to the test chemical resulted in a significant uptake and transfer of radiocarbon into the food chain elements. Bioaccumulation of radiocarbon in the body tissues of the organisms was low, as large amounts taken up were quickly eliminated through the excrements. The radiocarbon level of prey animals was about 100 times higher than that of their predators, but there was only small difference in concentration between collembolas and yeast. This was probably because of a faster excretion of the chemical by the beetles than by the collembolas. During the test period no conversion of [14C]PCP-Na took place in the yeast, but the collembolas and beetles metabolized 50 and 59%, respectively. Criteria are proposed for successful implementation of food chain models. PMID:3049045

  15. Terrestrial model food chain and environmental chemicals. I. Transfer of sodium (/sup 14/C)pentachlorophenate between springtails and carabids

    SciTech Connect

    Gruttke, H.; Kratz, W.; Weigmann, G.; Haque, A.

    1988-06-01

    A model soil food chain of a ruderal ecosystem has been constructed in order to study the uptake, transfer, and accumulation of (/sup 14/C)pentachlorophenate (PCP-Na). The model was based on three food levels, viz. baker's yeast, collembola, and carabid beetles, and the contaminant chemical introduced was via initial food. Continuous exposure of the organisms to the test chemical resulted in a significant uptake and transfer of radiocarbon into the food chain elements. Bioaccumulation of radiocarbon in the body tissues of the organisms was low, as large amounts taken up were quickly eliminated through the excrements. The radiocarbon level of prey animals was about 100 times higher than that of their predators, but there was only small difference in concentration between collembolas and yeast. This was probably because of a faster excretion of the chemical by the beetles than by the collembolas. During the test period no conversion of (/sup 14/C)PCP-Na took place in the yeast, but the collembolas and beetles metabolized 50 and 59%, respectively. Criteria are proposed for successful implementation of food chain models.

  16. Photoinitiated electron transfer to selected physisorbed alkyl bromides: The effects of alkyl chain length on dissociation cross sections

    SciTech Connect

    Khan, K.A.; Camillone, N. III; Osgood, R.M. Jr.

    1999-06-01

    We report the results of measurements of the cross section as a function of wavelength (351, 248, and 193 nm) for photoinitiated dissociative electron attachment to three normal alkyl bromides [CH{sub 3}(CH{sub 2}){sub n{minus}1}Br, n=1, 2, and 3] physisorbed on GaAs(110). Upon UV exposure, the molecules undergo C{endash}Br bond cleavage due to a substrate-mediated electron-transfer process. The cross sections for all three molecules increase monotonically with decreasing wavelength. Our results suggest a {approximately}1 eV higher threshold for dissociation of ethyl and propyl bromide than for methyl bromide. A simple model of the electron-transfer process is employed to estimate the peak per-electron cross section for dissociative attachment in the monolayer. We find that the cross sections for the physisorbed molecules are approximately five times smaller than those for gas-phase molecules, due to a reduction in the lifetime of the molecular anion in the vicinity of the surface. In addition, we also find an increase in cross section with chain length very similar to that observed in the gas phase; the gas-phase behavior has been explained by an increase in the anion lifetime with chain length. Our results suggest that while quenching of the molecular anion at the surface is important, it does not eliminate the progression of anion lifetime with chain length. {copyright} {ital 1999 American Institute of Physics.}

  17. MASS TRANSFER COEFFICIENTS FOR A NON-NEWTONIAN FLUID AND WATER WITH AND WITHOUT ANTI-FOAM AGENTS

    SciTech Connect

    Leishear, R.

    2009-09-09

    Mass transfer rates were measured in a large scale system, which consisted of an 8.4 meter tall by 0.76 meter diameter column containing one of three fluids: water with an anti-foam agent, water without an anti-foam agent, and AZ101 simulant, which simulated a non-Newtonian nuclear waste. The testing contributed to the evaluation of large scale mass transfer of hydrogen in nuclear waste tanks. Due to its radioactivity, the waste was chemically simulated, and due to flammability concerns oxygen was used in lieu of hydrogen. Different liquids were used to better understand the mass transfer processes, where each of the fluids was saturated with oxygen, and the oxygen was then removed from solution as air bubbled up, or sparged, through the solution from the bottom of the column. Air sparging was supplied by a single tube which was co-axial to the column, the decrease in oxygen concentration was recorded, and oxygen measurements were then used to determine the mass transfer coefficients to describe the rate of oxygen transfer from solution. Superficial, average, sparging velocities of 2, 5, and 10 mm/second were applied to each of the liquids at three different column fill levels, and mass transfer coefficient test results are presented here for combinations of superficial velocities and fluid levels.

  18. Approaching the Kinetic Inertness of Macrocyclic Gadolinium(III)-Based MRI Contrast Agents with Highly Rigid Open-Chain Derivatives.

    PubMed

    Tircsó, Gyula; Regueiro-Figueroa, Martín; Nagy, Viktória; Garda, Zoltán; Garai, Tamás; Kálmán, Ferenc Krisztián; Esteban-Gómez, David; Tóth, Éva; Platas-Iglesias, Carlos

    2016-01-18

    A highly rigid open-chain octadentate ligand (H4 cddadpa) containing a diaminocylohexane unit to replace the ethylenediamine bridge of 6,6'-[(ethane-1,2 diylbis{(carboxymethyl)azanediyl})bis(methylene)]dipicolinic acid (H4 octapa) was synthesized. This structural modification improves the thermodynamic stability of the Gd(3+) complex slightly (log KGdL =20.68 vs. 20.23 for [Gd(octapa)](-) ) while other MRI-relevant parameters remain unaffected (one coordinated water molecule; relaxivity r1 =5.73 mm(-1)  s(-1) at 20 MHz and 295 K). Kinetic inertness is improved by the rigidifying effect of the diaminocylohexane unit in the ligand skeleton (half-life of dissociation for physiological conditions is 6 orders of magnitude higher for [Gd(cddadpa)](-) (t1/2 =1.49×10(5)  h) than for [Gd(octapa)](-) . The kinetic inertness of this novel chelate is superior by 2-3 orders of magnitude compared to non-macrocyclic MRI contrast agents approved for clinical use. PMID:26583317

  19. 17 CFR 249b.102 - Form TA-2, 1 form to be used by transfer agents registered pursuant to section 17A of the...

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... Federal Register citations affecting Form TA-2, see the List of CFR Sections Affected, which appears in... annual report of transfer agent activities. 249b.102 Section 249b.102 Commodity and Securities Exchanges... Exchange Act of 1934 for the annual report of transfer agent activities. 1 Copies of the form may...

  20. Involvement of a cytosine side chain in proton transfer in the rate-determining step of ribozyme self-cleavage.

    PubMed

    Shih, I H; Been, M D

    2001-02-13

    Ribozymes of hepatitis delta virus have been proposed to use an active-site cytosine as an acid-base catalyst in the self-cleavage reaction. In this study, we have examined the role of cytosine in more detail with the antigenomic ribozyme. Evidence that proton transfer in the rate-determining step involved cytosine 76 (C76) was obtained from examining cleavage activity of the wild-type and imidazole buffer-rescued C76-deleted (C76 Delta) ribozymes in D(2)O and H(2)O. In both reactions, a similar kinetic isotope effect and shift in the apparent pKa indicate that the buffer is functionally substituting for the side chain in proton transfer. Proton inventory of the wild-type reaction supported a mechanism of a single proton transfer at the transition state. This proton transfer step was further characterized by exogenous base rescue of a C76 Delta mutant with cytosine and imidazole analogues. For the imidazole analogues that rescued activity, the apparent pKa of the rescue reaction, measured under k(cat)/K(M) conditions, correlated with the pKa of the base. From these data a Brønsted coefficient (beta) of 0.51 was determined for the base-rescued reaction of C76 Delta. This value is consistent with that expected for proton transfer in the transition state. Together, these data provide strong support for a mechanism where an RNA side chain participates directly in general acid or general base catalysis of the wild-type ribozyme to facilitate RNA cleavage. PMID:11171978

  1. Effect of charge transfer on chain dimension in trans-polyacetylene

    NASA Astrophysics Data System (ADS)

    Murthy, N. S.; Shacklette, L. W.; Baughman, R. H.

    1987-08-01

    X-ray diffraction measurements on all-trans-polyacetylene are consistent with a chain-axis length elongation upon donor doping (+0.026 Å for lithium and +0.04 Å for potassium) and a chain-axis length contraction upon acceptor doping (-0.010 Å for iodine), where the changes refer to the length L of a C2H2 unit (2.457 Å in the undoped polymer). These new experimentally derived results for heavily doped compositions, which ignore possible corrections for cell nonorthogonality in the lithium and iodine complexes, are similar to experimental results for graphite intercalation complexes and are consistent with theoretical predictions for doped polyacetylene. The meridional diffraction lines observed at L and L/2 for potassium-doped polyacetylene indicate that there is no lattice symmetry element which includes a translation operation of L/2 in the chain-axis direction. The observations are consistent with a structural model in which alkali-metal ions with an intracolumn spacing of 4.96 Å are commensurate with the polymer chains for the composition (CHM0.125)x. The likely polymer chain-axis repeat length is 2L (i.e., C4H4) and a lattice symmetry element which includes a translation of L is expected.

  2. Elucidation and Control of an Intramolecular Charge Transfer Property of Fucoxanthin by a Modification of Its Polyene Chain Length.

    PubMed

    Kosumi, Daisuke; Kajikawa, Takayuki; Okumura, Satoshi; Sugisaki, Mitsuru; Sakaguchi, Kazuhiko; Katsumura, Shigeo; Hashimoto, Hideki

    2014-03-01

    Fucoxanthin is an essential pigment for the highly efficient light-harvesting function of marine algal photosynthesis. It exhibits excited state properties attributed to intramolecular charge transfer (ICT) in polar environments due to the presence of the carbonyl group in its polyene backbone. This report describes the excited state properties of fucoxanthin homologues with four to eight conjugated double bonds in various solvents using the femtosecond pump-probe technique. The results clarified that fucoxanthin homologues with longer polyene chains did not possess pronounced ICT spectroscopic signatures, while the shorter fucoxanthin homologues had a strong ICT character, even in a nonpolar solvent. On the basis of the observations, we quantitatively correlated the ICT character in the excited state to the conjugated polyene chain lengths of fucoxanthin molecules. PMID:26274069

  3. Developing a Taxonomy and Model to Transfer and Assess Best Practices for Supply Chain Management

    NASA Astrophysics Data System (ADS)

    Flores, Myrna; Mendoza, Ana; Lavin, Victor; Flores, Benito

    Supply Chain Management can be briefly defined as the orchestration of a network of entities such as suppliers, distributors and clients to achieve a common goal: delivering cost efficient products and services exceeding customers’ expectations. Therefore, firms should consider all those End-to-End processes enabling an efficient integration and interoperability of partners collaborating in such Supply Chain when designing their Business Process Architecture (BPA). One key enabler to accomplish this goal is the identification, documentation and sharing of best practices. This paper describes the outcomes of a collaborative project carried out by CEMEX Research Group and the Universidad de Monterrey (UDEM), which focused on developing taxonomy to document best practices for the supply chain management together with a generic model to evaluate their level of implementation.

  4. Food chain transfer of selenium in lentic and lotic habitats of a western Canadian watershed

    SciTech Connect

    Orr, P.L.; Guiguer, K.R.; Russel, C.K.

    2006-02-15

    Selenium (Se) is an essential micronutrient, exhibiting a narrow margin between nutritionally optimal and potentially toxic concentrations. Egg-laying vertebrates at the top of aquatic food chains are most at risk in environments with elevated aqueous Se concentrations. The Elk River watershed in British Columbia, Canada receives effluents containing Se from five coal mine operations. This study tested three hypotheses that might account for higher Se concentrations in fish from lentic compared to lotic habitats in the watershed: (1) enhanced uptake by aquatic primary producers, (2) longer food chain length, or (3) greater food web accumulation through sediment-detrital pathways. Stable isotope and Se concentration data demonstrated that Se concentrations in aquatic primary producers and food chain lengths were comparable in lentic and lotic habitats. Enhanced formation of organoselenium and subsequent uptake and cycling via sediment detrital pathways likely account for higher fish tissue Se concentrations in lentic than in lotic areas.

  5. Markov chain formalism for polarized light transfer in plane-parallel atmospheres, with numerical comparison to the Monte Carlo method.

    PubMed

    Xu, Feng; Davis, Anthony B; West, Robert A; Esposito, Larry W

    2011-01-17

    Building on the Markov chain formalism for scalar (intensity only) radiative transfer, this paper formulates the solution to polarized diffuse reflection from and transmission through a vertically inhomogeneous atmosphere. For verification, numerical results are compared to those obtained by the Monte Carlo method, showing deviations less than 1% when 90 streams are used to compute the radiation from two types of atmospheres, pure Rayleigh and Rayleigh plus aerosol, when they are divided into sublayers of optical thicknesses of less than 0.03. PMID:21263634

  6. Impact of nuclear lattice relaxation on the excitation energy transfer along a chain of π -conjugated molecules

    NASA Astrophysics Data System (ADS)

    Schmid, S. A.; Abbel, R.; Schenning, A. P. H. J.; Meijer, E. W.; Herz, L. M.

    2010-02-01

    We have investigated the extent to which delocalization of the ground-state and excited-state wave functions of a π -conjugated molecule affects the excitation energy transfer (EET) between such molecules. Using femtosecond photoluminescence spectroscopy, we experimentally monitored the EET along well-defined supramolecular chains of extended conjugated molecules. Comparison with Monte Carlo simulations reveals that only a model incorporating a localized emitter and delocalized absorber wave function accurately reproduces these data. Our findings demonstrate that self-localization of the initially excited state, following fast relaxation of the nuclear lattice, has a significant impact on the EET dynamics in molecular assemblies.

  7. Enhancing Chinese Agribusiness Supply Chains with Internet Technologies: A Transnational Knowledge Transfer Approach

    ERIC Educational Resources Information Center

    Duan, Yanqing; Bentley, Yongmei; Fu, Zetian; Zografos, Konstantinos; Bemeleit, Boris

    2008-01-01

    This paper reports research findings from a project funded by the European Commission. The research used case studies and surveys to identify gaps between Europe and China in the level of Internet adoption in fresh-produce supply chains. The project reveals barriers to Internet adoption in China in this industry, and employs a transnational…

  8. Chemical genetics analysis of an aniline mustard anticancer agent reveals complex I of the electron transport chain as a target.

    PubMed

    Fedeles, Bogdan I; Zhu, Angela Y; Young, Kellie S; Hillier, Shawn M; Proffitt, Kyle D; Essigmann, John M; Croy, Robert G

    2011-09-30

    The antitumor agent 11β (CAS 865070-37-7), consisting of a DNA-damaging aniline mustard linked to an androgen receptor (AR) ligand, is known to form covalent DNA adducts and to induce apoptosis potently in AR-positive prostate cancer cells in vitro; it also strongly prevents growth of LNCaP xenografts in mice. The present study describes the unexpectedly strong activity of 11β against the AR-negative HeLa cells, both in cell culture and tumor xenografts, and uncovers a new mechanism of action that likely explains this activity. Cellular fractionation experiments indicated that mitochondria are the major intracellular sink for 11β; flow cytometry studies showed that 11β exposure rapidly induced oxidative stress, mitochondria being an important source of reactive oxygen species (ROS). Additionally, 11β inhibited oxygen consumption both in intact HeLa cells and in isolated mitochondria. Specifically, 11β blocked uncoupled oxygen consumption when mitochondria were incubated with complex I substrates, but it had no effect on oxygen consumption driven by substrates acting downstream of complex I in the mitochondrial electron transport chain. Moreover, 11β enhanced ROS generation in isolated mitochondria, suggesting that complex I inhibition is responsible for ROS production. At the cellular level, the presence of antioxidants (N-acetylcysteine or vitamin E) significantly reduced the toxicity of 11β, implicating ROS production as an important contributor to cytotoxicity. Collectively, our findings establish complex I inhibition and ROS generation as a new mechanism of action for 11β, which supplements conventional DNA adduct formation to promote cancer cell death. PMID:21832047

  9. Accumulation of potentially toxic elements in plants and element transfer to human food chain

    SciTech Connect

    Dudka, S.; Miller, W.P.

    1995-12-31

    This paper summarizes the biological pathways of cadmium, mercury, and lead into the human food chain; major sources of bioaccumulation; and exposure limits. For occupationally non-exposed persons and non-smokers, food is the main source of cadmium. About one-third of the total Cd burden originates from animal products and two-thirds from plant products. Consumption of fish and other aquatic animals is the main source of Hg intake by humans. The Provisional Tolerable Weekly Intake (PTWI) of Hg is achieved through occupational exposure or by consumption of large amounts of contaminated fish. About half of human Pb intake comes from food, of which more than half originates from plants. Drinking water and ingestion of Pb-rich soil and dust make up the other half of the Pb burden in humans. Cases of cadmium and methylmercury poisoning have been reported in Japan. No acute hazard from lead in the food chain has been determined so far.

  10. An 'adding' algorithm for the Markov chain formalism for radiation transfer

    NASA Technical Reports Server (NTRS)

    Esposito, L. W.

    1979-01-01

    An adding algorithm is presented, that extends the Markov chain method and considers a preceding calculation as a single state of a new Markov chain. This method takes advantage of the description of the radiation transport as a stochastic process. Successive application of this procedure makes calculation possible for any optical depth without increasing the size of the linear system used. It is determined that the time required for the algorithm is comparable to that for a doubling calculation for homogeneous atmospheres. For an inhomogeneous atmosphere the new method is considerably faster than the standard adding routine. It is concluded that the algorithm is efficient, accurate, and suitable for smaller computers in calculating the diffuse intensity scattered by an inhomogeneous planetary atmosphere.

  11. A QUANTUM MECHANICAL STUDY OF STRUCTURAL AND ELECTRONIC DILUTION EFFECTS IN PARAMAGNETIC CHEMICAL EXCHANGE SATURATION TRANSFER AGENTS

    PubMed Central

    Miller, Whelton A.; Moore, Preston B.

    2014-01-01

    We present a computational study of the effect of chemical modifications of the meta and para substituents in the coordinating pendant arm of a modified 1,4,7,10-tetraazacyclododecane-N, N’, N″, N‴-tetraamide (DOTAM) ligand on the Chemical Exchange Saturation Transfer (CEST) signal. Magnetic Resonance Imaging (MRI) is currently one of the most widely used techniques available. MRI has led to a new class of pharmaceuticals termed “imagining” or “contrast” agents. These agents usually work by incorporating lanthanide metals such as Gadolinium (Gd) and Europium (Eu). This allows the contrast agents to take advantage of the paramagnetic properties of the metals, which in turn enhances the signal detectable by MRI. The effect of simple electron-withdrawing (e.g., nitro) and electron-donating (e.g., methyl) substituents chemically attached to a modified chelate arm (pendant arm) is quantified by charge transfer interactions in the coordinated water-chelate system computed from quantum mechanics. This study attempts to reveal the origin of the substituent effect on the CEST signal and the electronic structure of the complex. We find that the extent of Charge Transfer (CT) depends on orbital orientations and overlaps. However, CT interactions occur simultaneously from all arms, which causes a dilution effect with respect to the pendant arm. PMID:25485283

  12. Transfer of radionuclides from high polluted bottom sediments to marine organisms through benthic food chain in post Fukushima period

    NASA Astrophysics Data System (ADS)

    Bezhenar, Roman; Jung, Kyung Tae; Maderich, Vladimir; Willemsen, Stefan; de With, Govert; Qiao, Fangli

    2015-04-01

    A catastrophic earthquake and tsunami occurred on March 11, 2011 and severely damaged the Fukushima Daiichi Nuclear Power Plant (FDNPP) that resulted in an uncontrolled release of radioactivity into air and ocean. Around 80% of the radioactivity released due to the FDNPP accident in March-April 2011 was either directly discharged into the ocean or deposited onto the ocean surface from the atmosphere. A large amount of long-lived radionuclides (mainly Cs-137) were released into the environment. The concentration of radionuclides in the ocean reached a maximum in mid-April of 2011, and then gradually decreased. From 2011 the concentration of Cs-137 in water essentially fell except the area around the FDNPP where leaks of contaminated water are continued. However, in the bottom sediment high concentrations of Cs-137 were found in the first months after the accident and slowly decreased with time. Therefore, it should be expected that a time delay is found of sediment-bound radionuclides in marine organisms. For the modeling of radionuclide transfer from highly polluted bottom sediments to marine organisms the dynamical food chain model BURN-POSEIDON (Heling et al, 2002; Maderich et al., 2014) was extended. In this model marine organisms are grouped into a limited number of classes based on their trophic level and type of species. These include: phytoplankton, zooplankton, fishes (two types: piscivorous and non-piscivorous), crustaceans, and molluscs for pelagic food chain and bottom sediment invertebrates, demersal fishes and bottom predators for benthic food chain and whole water column predators feeding by pelagial and benthic fishes. Bottom invertebrates consume organic parts of bottom sediments with adsorbed radionuclides which then migrate through the food chain. All organisms take radionuclides directly from water as well as via food. In fishes where radioactivity is not homogeneously distributed over all tissues of the organism, it is assumed that radionuclide

  13. Biomedical applications of polymers derived by reversible addition - fragmentation chain-transfer (RAFT).

    PubMed

    Fairbanks, Benjamin D; Gunatillake, Pathiraja A; Meagher, Laurence

    2015-08-30

    RAFT- mediated polymerization, providing control over polymer length and architecture as well as facilitating post polymerization modification of end groups, has been applied to virtually every facet of biomedical materials research. RAFT polymers have seen particularly extensive use in drug delivery research. Facile generation of functional and telechelic polymers permits straightforward conjugation to many therapeutic compounds while synthesis of amphiphilic block copolymers via RAFT allows for the generation of self-assembled structures capable of carrying therapeutic payloads. With the large and growing body of literature employing RAFT polymers as drug delivery aids and vehicles, concern over the potential toxicity of RAFT derived polymers has been raised. While literature exploring this complication is relatively limited, the emerging consensus may be summed up in three parts: toxicity of polymers generated with dithiobenzoate RAFT agents is observed at high concentrations but not with polymers generated with trithiocarbonate RAFT agents; even for polymers generated with dithiobenzoate RAFT agents, most reported applications call for concentrations well below the toxicity threshold; and RAFT end-groups may be easily removed via any of a variety of techniques that leave the polymer with no intrinsic toxicity attributable to the mechanism of polymerization. The low toxicity of RAFT-derived polymers and the ability to remove end groups via straightforward and scalable processes make RAFT technology a valuable tool for practically any application in which a polymer of defined molecular weight and architecture is desired. PMID:26050529

  14. Measurement of the uptake of a 14C-labelled fluorescent whitening agent by fish from water and through a model food chain.

    PubMed

    Feron, J P; Hitz, H R

    1975-01-01

    A laboratory technique is described which simulates the uptake of a fluorescent whitening agent by fish directly from the water and indirectly through a model food chain. The use of radioactive labelled material enables the direct and indirect uptake and possible accumulation of the compounds to be measured quantitatively. The results are expressed as concentration factors. Between ecological and toxicological data a safety relationship is established. PMID:1064532

  15. Plasmonics: Electromagnetic energy transfer and switching in nanoparticle chain-arrays below the diffraction limit

    NASA Astrophysics Data System (ADS)

    Brongersma, Mark; Hartman, John; Atwater, Harry

    2000-03-01

    Integrated optics faces the fundamental limitation that, for the guiding, modulation, and amplification of light, structures are needed that have dimensions comparable to the wavelength of light. Recently, it was theoretically shown that this problem can be circumvented by transporting electromagnetic energy along linear chains of closely spaced metal nanoparticles. This transport relies on the near-field electrodynamic interaction between metal particles that sets up coupled plasmon modes. We have modeled the transport properties of corners, T's, and switches that consist of chains of metal nanoparticles. It is shown that propagation is coherent and the group velocities can exceed saturated velocities of electrons in semiconductors ( ~ 105 m/s). High efficiency transmission of energy around sharp corners (bending radius << wavelength of visible light) is possible. The transmission is a strong function of the frequency and polarization direction of the plasmon mode. Finally, the operation of a plasmon switch is modeled in which plasmon waves can be switched. Suggestions are given for the choice of metal particle and host material. These "plasmonic devices" potentially are among the smallest structures with optical functionality.

  16. Characterization and Diagnostic Value of Amino Acid Side Chain Neutral Losses Following Electron-Transfer Dissociation

    NASA Astrophysics Data System (ADS)

    Xia, Qiangwei; Lee, M. Violet; Rose, Christopher M.; Marsh, Alyce J.; Hubler, Shane L.; Wenger, Craig D.; Coon, Joshua J.

    2011-02-01

    Using a large set of high mass accuracy and resolution ETD tandem mass spectra, we characterized ETD-induced neutral losses. From these data we deduced the chemical formula for 20 of these losses. Many of them have been previously observed in electron-capture dissociation (ECD) spectra, such as losses of the side chains of arginine, aspartic acid, glutamic acid, glutamine, asparagine, leucine, histidine, and carbamidomethylated cysteine residues. With this information, we examined the diagnostic value of these amino acid-specific losses. Among 1285 peptide-spectrum matches, 92.5% have agreement between neutral loss-derived peptide amino acid composition and the peptide sequences. Moreover, we show that peptides can be uniquely identified by using only the accurate precursor mass and amino acid composition based on neutral losses; the median number of sequence candidates from an accurate mass query is reduced from 21 to 8 by adding side chain loss information. Besides increasing confidence in peptide identification, our findings suggest the potential use of these diagnostic losses in ETD spectra to improve false discovery rate estimation and to enhance the performance of scoring functions in database search algorithms.

  17. Turning the corner: efficient energy transfer in bent plasmonic nanoparticle chain waveguides.

    PubMed

    Solis, David; Paul, Aniruddha; Olson, Jana; Slaughter, Liane S; Swanglap, Pattanawit; Chang, Wei-Shun; Link, Stephan

    2013-10-01

    For integrating and multiplexing of subwavelength plasmonic waveguides with other optical and electric components, complex architectures such as junctions with sharp turns are necessary. However, in addition to intrinsic losses, bending losses severely limit plasmon propagation. In the current work, we demonstrate that propagation of surface plasmon polaritons around 90° turns in silver nanoparticle chains occurs without bending losses. Using a far-field fluorescence method, bleach-imaged plasmon propagation (BlIPP), which creates a permanent map of the plasmonic near-field through bleaching of a fluorophore coated on top of a plasmonic waveguide, we measured propagation lengths at 633 nm for straight and bent silver nanoparticle chains of 8.0 ± 0.5 and 7.8 ± 0.4 μm, respectively. These propagation lengths were independent of the input polarization. We furthermore show that subradiant plasmon modes yield a longer propagation length compared to energy transport via excitation of super-radiant modes. PMID:24020385

  18. The transfer and fate of Pb from sewage sludge amended soil in a multi-trophic food chain: a comparison with the labile elements Cd and Zn.

    PubMed

    Dar, Mudasir Irfan; Khan, Fareed Ahmad; Green, Iain D; Naikoo, Mohd Irfan

    2015-10-01

    The contamination of agroecosystems due to the presence of trace elements in commonly used agricultural materials is a serious issue. The most contaminated material is usually sewage sludge, and the sustainable use of this material within agriculture is a major concern. This study addresses a key issue in this respect, the fate of trace metals applied to soil in food chains. The work particularly addresses the transfer of Pb, which is an understudied element in this respect, and compares the transfer of Pb with two of the most labile metals, Cd and Zn. The transfer of these elements was determined from sludge-amended soils in a food chain consisting of Indian mustard (Brassica juncea), the mustard aphid (Lipaphis erysimi) and a predatory beetle (Coccinella septempunctata). The soil was amended with sludge at rates of 0, 5, 10 and 20 % (w/w). Results showed that Cd was readily transferred through the food chain until the predator trophic level. Zn was the most readily transferred element in the lower trophic levels, but transfer to aphids was effectively restricted by the plant regulating shoot concentration. Pb had the lowest level of transfer from soil to shoot and exhibited particular retention in the roots. Nevertheless, Pb concentrations were significantly increased by sludge amendment in aphids, and Pb was increasingly transferred to ladybirds as levels increased. The potential for Pb to cause secondary toxicity to organisms in higher trophic levels may have therefore been underestimated. PMID:26070738

  19. Uptake and transfer of14C-simetryne through the laboratory freshwater food chain

    NASA Astrophysics Data System (ADS)

    Xu, Ying; Lay, J. P.; Zhang, Yongyuan

    1989-03-01

    This paper deals with the bioconcentration of14C-simetryne from water by aquatic test organisms: green algae— Monoraphidium minutum, rotifers— Brachionus rubens, daphnids— Daphnia magna, and fish— Brachydanio rerio. The chemical was bioconcentrated rapidly in all test species during the first 48 hours of experiment. The BCF values (bioconcentration factor) from all uptake studies show that simetryne has higher accumulation in algae than in rotifers, daphnids and zebra fish. The logarithm of the n-octanol/water partition coefficient of simetryne measured as 2.06±0.05 was correlated with the BCFs in the organisms as based on the lipid contents. 14C-simetryne uptake via the food-chain amounted to only 22% to 42% of the bioconcentration from water. Clearance of14C-derived residues from fish was rapid with a half-life of 2.1 days.

  20. Medium-chain fatty acid binding to albumin and transfer to phospholipid bilayers

    SciTech Connect

    Hamilton, J.A. )

    1989-04-01

    Temperature-dependent (5-42{degree}C) {sup 13}C NMR spectra of albumin complexes with 90% isotopically substituted (1-{sup 13}C)octanoic or (1-{sup 13}C)decanoic acids showed a single peak at >30{degree}C but three peaks at lower temperatures. The chemical-shift differences result from different ionic and/or hydrogen-bonding interactions between amino acid side chains and the fatty acid carboxyl carbon. Rapid exchange of fatty acid among binding sites obscures these sites at temperatures >30{degree}C. Rate constants for exchange at 33{degree}C were 350 sec{sup {minus}1} for octanoate and 20 sec {sup {minus}1} for decanoate. Temperature-dependent data for octanoate showed an activation energy of 2 kcal/mol for exchange. Spectra of albumin complexes with the 12-carbon saturated fatty acid, lauric acid, had several narrow laurate carboxyl peaks at 35{degree}C, indicating longer lifetimes in the different binding sites. Fatty acid exchange between albumin and model membranes (phosphatidylcholine bilayers) occurred on a time scale comparable to that for exchange among albumin binding sites, following the order octanoate > decanoate > laurate. The equilibrium distribution of fatty acid between lipid bilayers and protein was measured directly from NMR spectra. Decreasing pH increased the relative affinity of fatty acid for the lipid bilayer. The results predict that the relative affinity of octanoic acid for albumin and membranes will be similar to that of long-chain fatty acids, but the rate of equilibration will be {approx} 10{sup 4} faster for octanoic acid.

  1. Food chain transfer and potential renal toxicity of mercury to small mammals at a contaminated terrestrial field site.

    PubMed

    Talmage, S S; Walton, B T

    1993-12-01

    Mercury concentrations were determined in surface soil and biota at a contaminated terrestrial field site and were used to calculate transfer coefficients of mercury through various compartments of the ecosystem based on trophic relationships. Mercury concentrations in all compartments (soil, vegetation, invertebrates, and small mammals) were higher than mercury concentrations in corresponding samples at local reference sites. Nonetheless, mercury concentrations in biota did not exceed concentrations in the contaminated surface soil, which averaged 269 μg g(-1). Plant tissue concentrations of mercury were low (0.01 to 2.0 μg g(-1)) and yielded soil to plant transfer coefficients ranging from 3.7×10(-5) for seeds to 7.0×10(-3) for grass blades. Mercury concentrations in invertebrates ranged from 0.79 for harvestmen (Phalangida) to 15.5 μg g(-1) for undepurated earthworms (Oligochaeta). Mean food chain transfer coefficients for invertebrates were 0.88 for herbivores/omnivores and 2.35 for carnivores. Mean mercury concentrations in target tissue (kidney) were 1.16±1.16 μg g(-1) for the white-footed mouse (Peromyscus leucopus), a granivore, and 38.8±24.6 μg g(-1) for the shorttail shrew (Blarina brevicauda), an insectivore. Transfer coefficients for diet to kidney were 0.75 and 4.40 for P. leucopus and B. brevicauda, respectively. A comparison of kidney mercury residues measured in this study with values from controlled laboratory feeding studies from the literature indicate that B. brevicauda but not P. leucopus may be ingesting mercury at levels that are nephrotoxic. PMID:24201735

  2. Surface-imprinted magnetic particles for highly selective sulfonamides recognition prepared by reversible addition fragmentation chain transfer polymerization.

    PubMed

    Xie, Xiaoyu; Liu, Xia; Pan, Xiaoyan; Chen, Liang; Wang, Sicen

    2016-01-01

    In this work, novel magnetic molecularly imprinted polymers (MMIPs) were prepared by reversible addition fragmentation chain transfer (RAFT) polymerization using sulfamerazine as the template. With the controlled/living property of RAFT polymerization, the resulting MMIPs showed high selectivity for sulfonamides recognition. The MMIPs were characterized by transmission electron microscopy, Fourier transform infrared, vibrating sample magnetometer, X-ray diffraction, X-ray photoelectron spectroscopy, and thermogravimetric analysis. The static and selectivity binding experiments demonstrated the desirable adsorption capacity and high selectivity of the MMIPs. The developed MMIPs were used as the solid-phase extraction sorbents to selectively extract four sulfonamides from aqueous solution. The recoveries of the spiked pond water ranged from 61.2 to 94.1% with RSD lower than 6.5%. This work demonstrated a versatile approach for the preparation of well-constructed MMIPs for application in the field of solid-phase extraction. PMID:26637219

  3. A Small Molecule That Protects the Integrity of the Electron Transfer Chain Blocks the Mitochondrial Apoptotic Pathway.

    PubMed

    Jiang, Xian; Li, Li; Ying, Zhengxin; Pan, Chenjie; Huang, Shaoqiang; Li, Lin; Dai, Miaomiao; Yan, Bo; Li, Ming; Jiang, Hui; Chen, She; Zhang, Zhiyuan; Wang, Xiaodong

    2016-07-21

    In response to apoptotic stimuli, mitochondria in mammalian cells release cytochrome c and other apoptogenic proteins, leading to the subsequent activation of caspases and apoptotic cell death. This process is promoted by the pro-apoptotic members of the Bcl-2 family of proteins, such as Bim and Bax, which, respectively, initiate and execute cytochrome c release from the mitochondria. Here we report the discovery of a small molecule that efficiently blocks Bim-induced apoptosis after Bax is activated on the mitochondria. The cellular target of this small molecule was identified to be the succinate dehydrogenase subunit B (SDHB) protein of complex II of the mitochondrial electron transfer chain (ETC). The molecule protects the integrity of the ETC and allows treated cells to continue to proliferate after apoptosis induction. Moreover, this molecule blocked dopaminergic neuron death and reversed Parkinson-like behavior in a rat model of Parkinson's disease. PMID:27447985

  4. DNAzyme-based biosensor for Cu(2+) ion by combining hybridization chain reaction with fluorescence resonance energy transfer technique.

    PubMed

    Chen, Ying; Chen, Ling; Ou, Yidian; Wang, Zhenhua; Fu, Fengfu; Guo, Liangqia

    2016-08-01

    A novel signal amplification strategy based on Cu(2+)-dependent DNAzyme was developed for sensing Cu(2+) ion by combining hybridization chain reaction (HCR) with fluorescence resonance energy transfer (FRET) technique. In the presence of Cu(2+) ion, the substrate strands of Cu(2+)-dependent DNAzyme immobilized on magnetic beads were specifically cleaved and released. The released strands initiated the HCR process of hairpin H1 and H2 labeled with FAM as the donor and TAMRA as the acceptor, respectively. Long nicked dsDNA structures were self-assembled to bring the donor and the acceptor in close proximity, resulting in a FRET process. The relative ratio of fluorescent intensities of the acceptor and donor was used to quantitatively detect Cu(2+) ion with a limit of detection of 0.5nmolL(-1). This proposed biosensor was applied to detect Cu(2+) ion in tap water with satisfactory results. PMID:27216680

  5. AQUEOUS TOXICITY AND FOOD CHAIN TRANSFER OF QUANTUM DOTS™ IN FRESHWATER ALGAE AND CERIODAPHNIA DUBIA

    PubMed Central

    Bouldin, Jennifer L.; Ingle, Taylor M.; Sengupta, Anindita; Alexander, Regina; Hannigan, Robyn E.; Buchanan, Roger A.

    2011-01-01

    Innovative research and diagnostic techniques for biological testing have advanced during recent years because of the development of semiconductor nanocrystals. Although these commercially available, fluorescent nanocrystals have a protective organic coating, the inner core contains cadmium and selenium. Because these metals have the potential for detrimental environmental effects, concerns have been raised over our lack of understanding about the environmental fate of these products. U.S. Environmental Protection Agency test protocol and fluorescence microscopy were used to determine the fate and effect of quantum dots (QDs; Qdot® 545 ITK™ Carboxyl Quantum Dots [Fisher Scientific, Fisher part Q21391MP; Invitrogen Molecular Probes, Eugene, OR, USA]) using standard aquatic test organisms. No lethality was measured following 48-h exposure of Ceriodaphnia dubia to QD suspensions as high as 110 ppb, but the 96-h median lethal concentration to Pseudokirchneriella subcapitata was measured at 37.1 ppb. Transfer of QDs from dosed algae to C. dubia was verified with fluorescence microscopy. These results indicate that coatings present on nanocrystals provide protection from metal toxicity during laboratory exposures but that the transfer of core metals from intact nanocrystals may occur at levels well above toxic threshold values, indicating the potential exposure of higher trophic levels. Studies regarding the fate and effects of nanoparticles can be incorporated into models for predictive toxicology of these emerging contaminants. PMID:19086211

  6. Transfer of {sup 210}Po and {sup 210}Pb through the lichen-caribou-wolf food chain of northern Canada

    SciTech Connect

    Thomas, P.A.; Sheard, J.W.; Swanson, S.

    1994-06-01

    Natural background activity and food chain transfer of the uranium decay products, {sup 210}Po and {sup 210}Pb, were examined in the lichen-caribou-wolf food chain at two locations in the Northwest Territories of Canada. {sup 210}Po and {sup 210}Pb activities in lichens differed with species and location. Both {sup 210}Po and {sup 210}Pb were markedly higher in caribou bone than in wolf bone. {sup 210}Po activities in liver, kidney, and muscle were similar in both species. Caribou fetuses had lower activities of {sup 210}Po but higher activities of {sup 210}Pb than maternal muscle and placenta, suggesting greater placental transport of {sup 210}Pb than {sup 210}Po. Concentration ratios (CR = Bq kg{sup {minus}1} in consumer/Bq kg{sup {minus}1} in its food source) and f{sub f} values (f{sub f} in d kg{sup {minus}1} = Bq kg{sup {minus}1} in muscle/Bq d{sup {minus}1} ingested) showed that wolves retain more {sup 210}Po and less {sup 210}Pb from their diet than do caribou. {sup 210}Po CRs averaged 0.38 for caribou/lichens, 0.26 for caribou/rumen contents, and 0.40 for wolves/caribou. {sup 210}Pb CRs averaged 0.36 for caribou/lichens, 0.57 for caribou/rumen contents, and 0.13 for wolves/caribou. 43 refs., 4 figs., 5 tabs.

  7. Unraveling the Interplay of Backbone Rigidity and Electron Rich Side-Chains on Electron Transfer in Peptides: The Realization of Tunable Molecular Wires

    PubMed Central

    2015-01-01

    Electrochemical studies are reported on a series of peptides constrained into either a 310-helix (1–6) or β-strand (7–9) conformation, with variable numbers of electron rich alkene containing side chains. Peptides (1 and 2) and (7 and 8) are further constrained into these geometries with a suitable side chain tether introduced by ring closing metathesis (RCM). Peptides 1, 4 and 5, each containing a single alkene side chain reveal a direct link between backbone rigidity and electron transfer, in isolation from any effects due to the electronic properties of the electron rich side-chains. Further studies on the linear peptides 3–6 confirm the ability of the alkene to facilitate electron transfer through the peptide. A comparison of the electrochemical data for the unsaturated tethered peptides (1 and 7) and saturated tethered peptides (2 and 8) reveals an interplay between backbone rigidity and effects arising from the electron rich alkene side-chains on electron transfer. Theoretical calculations on β-strand models analogous to 7, 8 and 9 provide further insights into the relative roles of backbone rigidity and electron rich side-chains on intramolecular electron transfer. Furthermore, electron population analysis confirms the role of the alkene as a “stepping stone” for electron transfer. These findings provide a new approach for fine-tuning the electronic properties of peptides by controlling backbone rigidity, and through the inclusion of electron rich side-chains. This allows for manipulation of energy barriers and hence conductance in peptides, a crucial step in the design and fabrication of molecular-based electronic devices. PMID:25122122

  8. Early Career: Templating of Liquid Crystal Microstructures by Reversible Addition-Fragmentation Chain Transfer Polymerization

    SciTech Connect

    Heinen, Jennifer M

    2014-12-31

    This research has shown that the microstructure of self-assembled copolymers can be decoupled from the polymer chemistry. The simplest polymer architecture, linear block copolymers, is valuable for a broad range of applications, including adhesives and coatings, medical devices, electronics and energy storage, because these block copolymers reproducibly self-assemble into microphase separated nanoscale domains. Unfortunately, the self-assembled microstructure is tuned by polymer composition, thus limiting the potential to simultaneously optimize chemical, mechanical, and transport properties for desired applications. To this end, much work was been put into manipulating block copolymer self-assembly independently of polymer composition. These efforts have included the use of additives or solvents to alter polymer chain conformation, the addition of a third monomer to produce ABC triblock terpolymers, architectures with mixed blocks, such as tapered/gradient polymers, and the synthesis of other nonlinear molecular architectures. This work has shown that the microstructures formed by linear ABC terpolymers can be altered by controlling the architecture of the polymer molecules at a constant monomer composition, so that the microstructure is tuned independently from the chemical properties.

  9. Arsenic Contamination in Food-chain: Transfer of Arsenic into Food Materials through Groundwater Irrigation

    PubMed Central

    Joardar, J.C.; Parvin, S.; Correll, Ray; Naidu, Ravi

    2006-01-01

    Arsenic contamination in groundwater in Bangladesh has become an additional concern vis-à-vis its use for irrigation purposes. Even if arsenic-safe drinking-water is assured, the question of irrigating soils with arsenic-laden groundwater will continue for years to come. Immediate attention should be given to assess the possibility of accumulating arsenic in soils through irrigation-water and its subsequent entry into the food-chain through various food crops and fodders. With this possibility in mind, arsenic content of 2,500 water, soil and vegetable samples from arsenic-affected and arsenic-unaffected areas were analyzed during 1999–2004. Other sources of foods and fodders were also analyzed. Irrigating a rice field with groundwater containing 0.55 mg/L of arsenic with a water requirement of 1,000 mm results in an estimated addition of 5.5 kg of arsenic per ha per annum. Concentration of arsenic as high as 80 mg per kg of soil was found in an area receiving arsenic-contaminated irrigation. A comparison of results from affected and unaffected areas revealed that some commonly-grown vegetables, which would usually be suitable as good sources of nourishment, accumulate substantially-elevated amounts of arsenic. For example, more than 150 mg/kg of arsenic has been found to be accumulated in arum (kochu) vegetable. Implications of arsenic ingested in vegetables and other food materials are discussed in the paper. PMID:17366772

  10. Imaging In Vivo Extracellular pH with a Single Paramagnetic Chemical Exchange Saturation Transfer Magnetic Resonance Imaging Contrast Agent

    PubMed Central

    Liu, Guanshu; Li, Yuguo; Sheth, Vipul R.; Pagel, Mark D.

    2016-01-01

    The measurement of extracellular pH (pHe) has potential utility for cancer diagnoses and for assessing the therapeutic effects of pH-dependent therapies. A single magnetic resonance imaging (MRI) contrast agent that is detected through paramagnetic chemical exchange saturation transfer (PARACEST) was designed to measure tumor pHe throughout the range of physiologic pH and with magnetic resonance saturation powers that are not harmful to a mouse model of cancer. The chemical characterization and modeling of the contrast agent Yb3+-1,4,7,10-tetraazacyclododecane-1,4,7-triacetic acid,10-o-aminoanilide (Yb-DO3A-oAA) suggested that the aryl amine of the agent forms an intramolecular hydrogen bond with a proximal carboxylate ligand, which was essential for generating a practical chemical exchange saturation transfer (CEST) effect from an amine. A ratio of CEST effects from the aryl amine and amide was linearly correlated with pH throughout the physiologic pH range. The pH calibration was used to produce a parametric pH map of a subcutaneous flank tumor on a mouse model of MCF-7 mammary carcinoma. Although refinements in the in vivo CEST MRI methodology may improve the accuracy of pHe measurements, this study demonstrated that the PARACEST contrast agent can be used to generate parametric pH maps of in vivo tumors with saturation power levels that are not harmful to a mouse model of cancer. PMID:22418027

  11. A pH-Responsive MRI Agent that Can Be Activated Beyond the Tissue Magnetization Transfer Window.

    PubMed

    Wang, Xiaojing; Wu, Yunkou; Soesbe, Todd C; Yu, Jing; Zhao, Piyu; Kiefer, Garry E; Sherry, A Dean

    2015-07-20

    A terbium-based complex that displays a water exchange CEST resonance well outside the normal magnetization transfer (MT) frequency range of tissues provides a direct readout of pH values by MRI. Deprotonation of the phenolic proton in this complex results in a frequency shift of 56 ppm in a bound water molecule exchange peak between pH 5 and 8. This allows direct imaging of pH without prior knowledge of the agent concentration and with essentially no interference from the tissue MT signal. PMID:26096197

  12. Role of Humic-Bound Iron as an Electron Transfer Agent in Dissimilatory Fe(III) Reduction

    PubMed Central

    Lovley, Derek R.; Blunt-Harris, Elizabeth L.

    1999-01-01

    The dissimilatory Fe(III) reducer Geobacter metallireducens reduced Fe(III) bound in humic substances, but the concentrations of Fe(III) in a wide range of highly purified humic substances were too low to account for a significant portion of the electron-accepting capacities of the humic substances. Furthermore, once reduced, the iron in humic substances could not transfer electrons to Fe(III) oxide. These results suggest that other electron-accepting moieties in humic substances, such as quinones, are the important electron-accepting and shuttling agents under Fe(III)-reducing conditions. PMID:10473447

  13. 77 FR 61083 - Possession, Use, and Transfer of Select Agents and Toxins; Biennial Review

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-10-05

    ... Advance Notice of Proposed Rulemaking (ANPRM) (75 FR 42363) on July 21, 2010 and a Notice of Proposed Rulemaking (NPRM) (76 FR 61206) on October 3, 2011. The NPRM solicited comments regarding (1) the... adding the haemorrhagic fever virus Chapare, to the list of select agents (74 FR 41829). Chapare virus...

  14. 76 FR 61205 - Possession, Use, and Transfer of Select Agents and Toxins; Biennial Review

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-10-03

    ... Register on October 16, 2008 (73 FR 61363). The HHS select agents and toxins list is divided into two... ANPRM in the Federal Register (75 FR 42363) (July 21, 2010 ANPRM) inviting comments concerning potential... and toxins. Proposed Addition of Lujo and Chapare Viruses On August 19, 2009 (74 FR 41829),...

  15. The transfer of titanium dioxide nanoparticles from the host plant to butterfly larvae through a food chain

    NASA Astrophysics Data System (ADS)

    Kubo-Irie, Miyoko; Yokoyama, Masaaki; Shinkai, Yusuke; Niki, Rikio; Takeda, Ken; Irie, Masaru

    2016-03-01

    This study aimed to examine the transfer of nanoparticles within a terrestrial food chain. Oviposited eggs of the swallowtail butterfly (Atrophaneura alcinous) were hatched on the leaves of the host plant (Aristolochia debilis), and the root stock and root hairs were submerged in a suspension of 10 μg/ml titanium dioxide nanoparticles (TiO2-NPs) in a 100 ml bottle. The presence of TiO2-NPs in the veins of the leaves was confirmed by X-ray analytical microscopy (X-ray AM). The hatched 1st instar larvae fed on the leaves to moult into 2nd instar larvae. Small agglomerates of TiO2-NPs less than 150 nm in diameter were identified in the vascular tissue of the exposed plant, the midgut and the excreta of the larvae by transmission electron microscopy. The image of Ti elemental mapping by X-ray AM was analysed with the quantitative spatial information mapping (QSIM) technique. The results demonstrated that TiO2-NPs were transferred from the plant to the larvae and they were disseminated throughout the environment via larval excreta.

  16. Direct 'in situ', low VOC, high yielding, CO2 expanded phase catalytic chain transfer polymerisation: towards scale-up.

    PubMed

    Adlington, Kevin; Green, Anthony; Wang, Wenxin; Howdle, Steven M; Irvine, Derek J

    2013-01-01

    The successful application of catalytic chain transfer polymerisation (CCTP) by adopting an 'in situ' catalyst preparation methodology in several polymerisation media is described. More specifically, this study is focused on reporting the development of 'in situ' CCTP within a CO(2) expanded phase polymerisation process, which achieved high yields of polymer whilst minimising both VOC footprint and CO(2) compression costs. The 'in situ' method is shown to be effective in controlling polymerisations conducted in both conventional solvents and bulk under inert atmosphere, delivering molecular weight reductions and a Cs value of appropriate similar magnitude to those achieved by the benchmark, commercially sourced CoPhBF catalyst. The 'in situ' effect has been achieved with equal efficiency when both using catalysts with different axial ligands and where the complex is required to undergo a facile ligand dissociation in order to create the required catalyst necessary to achieve CCTP control. Furthermore, both catalysts are shown to effectively control polymerisations in a CO(2) expanded phase process, in which a small amount of compressed CO(2) is introduced to reduce the viscosity of the reaction mixture, allowing for easy heat transfer and good catalyst diffusion during reaction. In this way, yield limitations imposed to avoid the Trommsdorff effect required in bulk processing and the need for post precipitation have been successfully overcome. Both of these factors further improve the sustainability of such a polymerisation process. However, the 'in situ', high pressure expanded phase environment was observed to retard the ligand dissociation required for catalyst activation. PMID:23085824

  17. The transfer of titanium dioxide nanoparticles from the host plant to butterfly larvae through a food chain

    PubMed Central

    Kubo-Irie, Miyoko; Yokoyama, Masaaki; Shinkai, Yusuke; Niki, Rikio; Takeda, Ken; Irie, Masaru

    2016-01-01

    This study aimed to examine the transfer of nanoparticles within a terrestrial food chain. Oviposited eggs of the swallowtail butterfly (Atrophaneura alcinous) were hatched on the leaves of the host plant (Aristolochia debilis), and the root stock and root hairs were submerged in a suspension of 10 μg/ml titanium dioxide nanoparticles (TiO2-NPs) in a 100 ml bottle. The presence of TiO2-NPs in the veins of the leaves was confirmed by X-ray analytical microscopy (X-ray AM). The hatched 1st instar larvae fed on the leaves to moult into 2nd instar larvae. Small agglomerates of TiO2-NPs less than 150 nm in diameter were identified in the vascular tissue of the exposed plant, the midgut and the excreta of the larvae by transmission electron microscopy. The image of Ti elemental mapping by X-ray AM was analysed with the quantitative spatial information mapping (QSIM) technique. The results demonstrated that TiO2-NPs were transferred from the plant to the larvae and they were disseminated throughout the environment via larval excreta. PMID:27030539

  18. Effect of the zebra mussel (Dreissena polymorpha) on food-chain transfer of PCBs in Saginaw Bay

    SciTech Connect

    Hoof, P.L. Van; Hsieh, J.L.; Eadie, B.J.; Lansing, M.B.

    1995-12-31

    The recent invasion of the zebra mussel (Dreissena polymorpha) has significantly impacted the water quality of the Great Lakes. Relatively little is known about the influence of zebra mussels on contaminant cycling, and transfer to higher trophic organisms. Due to its high filtering rate and ability to rapidly establish large populations, Dreissena could potentially alter the flow of energy through the food web. In addition, this species has demonstrated a large capacity for accumulating lipophilic organic contaminants such as polychlorinated biphenyls (PCBs). Thus, zebra mussels could contribute to enhanced contaminant biomagnification by serving as an additional food-chain link either through direct transfer (ingestion by fish or ducks), and/or indirectly by funneling contaminants out of the pelagic zone down to benthic invertebrates. In order to determine if zebra mussels are enhancing biomagnification of PCBs in a Saginaw Bay food web, two years of field collections of various components (water, sediment, algae, zooplankton, zebra mussel, zebra mussel feces, gammarid amphipods, fish) were analyzed for their PCB congener content. Trophic levels will be characterized using stable isotope ratios of {sup 15}N/{sup 14}N, whereas carbon sources will be identified using {sup 13}C/{sup 13}C ratios.

  19. Phospho-transfer networks and ATP homeostasis in response to an ineffective electron transport chain in Pseudomonas fluorescens.

    PubMed

    Appanna, V P; Alhasawi, A A; Auger, C; Thomas, S C; Appanna, V D

    2016-09-15

    Although oxidative stress is known to impede the tricarboxylic acid (TCA) cycle and oxidative phosphorylation, the nutritionally-versatile microbe, Pseudomonas fluorescens has been shown to proliferate in the presence of hydrogen peroxide (H2O2) and nitrosative stress. In this study we demonstrate the phospho-transfer system that enables this organism to generate ATP was similar irrespective of the carbon source utilized. Despite the diminished activities of enzymes involved in the TCA cycle and in the electron transport chain (ETC), the ATP levels did not appear to be significantly affected in the stressed cells. Phospho-transfer networks mediated by acetate kinase (ACK), adenylate kinase (AK), and nucleoside diphosphate kinase (NDPK) are involved in maintaining ATP homeostasis in the oxidatively-challenged cells. This phospho-relay machinery orchestrated by substrate-level phosphorylation is aided by the up-regulation in the activities of such enzymes like phosphoenolpyruvate carboxylase (PEPC), pyruvate orthophosphate dikinase (PPDK), and phosphoenolpyruvate synthase (PEPS). The enhanced production of phosphoenolpyruvate (PEP) and pyruvate further fuel the synthesis of ATP. Taken together, this metabolic reconfiguration enables the organism to fulfill its ATP need in an O2-independent manner by utilizing an intricate phospho-wire module aimed at maximizing the energy potential of PEP with the participation of AMP. PMID:27431058

  20. The transfer of titanium dioxide nanoparticles from the host plant to butterfly larvae through a food chain.

    PubMed

    Kubo-Irie, Miyoko; Yokoyama, Masaaki; Shinkai, Yusuke; Niki, Rikio; Takeda, Ken; Irie, Masaru

    2016-01-01

    This study aimed to examine the transfer of nanoparticles within a terrestrial food chain. Oviposited eggs of the swallowtail butterfly (Atrophaneura alcinous) were hatched on the leaves of the host plant (Aristolochia debilis), and the root stock and root hairs were submerged in a suspension of 10 μg/ml titanium dioxide nanoparticles (TiO2-NPs) in a 100 ml bottle. The presence of TiO2-NPs in the veins of the leaves was confirmed by X-ray analytical microscopy (X-ray AM). The hatched 1st instar larvae fed on the leaves to moult into 2nd instar larvae. Small agglomerates of TiO2-NPs less than 150 nm in diameter were identified in the vascular tissue of the exposed plant, the midgut and the excreta of the larvae by transmission electron microscopy. The image of Ti elemental mapping by X-ray AM was analysed with the quantitative spatial information mapping (QSIM) technique. The results demonstrated that TiO2-NPs were transferred from the plant to the larvae and they were disseminated throughout the environment via larval excreta. PMID:27030539

  1. Toxic heritage: Maternal transfer of pyrethroid insecticides and sunscreen agents in dolphins from Brazil.

    PubMed

    Alonso, Mariana B; Feo, Maria Luisa; Corcellas, Cayo; Gago-Ferrero, Pablo; Bertozzi, Carolina P; Marigo, Juliana; Flach, Leonardo; Meirelles, Ana Carolina O; Carvalho, Vitor L; Azevedo, Alexandre F; Torres, João Paulo M; Lailson-Brito, José; Malm, Olaf; Diaz-Cruz, M Silvia; Eljarrat, Ethel; Barceló, Damià

    2015-12-01

    Pyrethroids (PYR) and UV filters (UVF) were investigated in tissues of paired mother-fetus dolphins from Brazilian coast in order to investigate the possibility of maternal transfer of these emerging contaminants. Comparison of PYR and UVF concentrations in maternal and fetal blubber revealed Franciscana transferred efficiently both contaminants to fetuses (F/M > 1) and Guiana dolphin transferred efficiently PYR to fetuses (F/M > 1) different than UVF (F/M < 1). PYR and UVF concentrations in fetuses were the highest-ever reported in biota (up to 6640 and 11,530 ng/g lw, respectively). Muscle was the organ with the highest PYR and UVF concentrations (p < 0.001), suggesting that these two classes of emerging contaminants may have more affinity for proteins than for lipids. The high PYR and UVF concentrations found in fetuses demonstrate these compounds are efficiently transferred through placenta. This study is the first to report maternal transfer of pyrethroids and UV filters in marine mammals. PMID:26453834

  2. Correlation of chain length compatibility and surface properties of mixed foaming agents with fluid displacement efficiency and effective air mobility in porous media

    SciTech Connect

    Sharma, M.K.; Bringham, W.E.; Shah, D.O.

    1984-05-01

    The effects of chain length compatibility and surface properties of mixed foaming agents on fluid displacement efficiency and effective air mobility in porous media were investigated. Sodium dodecyl sulfate (C/sub 12/H/sub 25/SO/sub 4/Na) and various alkyl alcohols (e.g., C/sub 8/OH,C/sub 10/OH,C/sub 12/OH,C/sub 14/OH, and C/sub 16/OH) were used as mixed foaming agents. It was observed that the surface properties of surfactant solutions and flow behavior of foams through porous media were influenced by the chain length compatibility of the surfactant molecules. The increase in the length of porous media improved fluid displacement efficiency while breakthrough time per unit length decreased slightly with increase in the length of porous media. For mixed surfactant systems, a minimum in surface tension, a maximum in surface viscosity, a minimum in bubble size, a maximum in breakthrough time, a maximum in fluid displacement efficiency, and a minimum in effective air mobility were observed when the two components of the surfactant system had the same chain length. These results indicate that the surface properties of foaming solutions and molecular packing at interfaces exhibit a striking correlation with breakthrough time, fluid displacement efficiency, and effective air mobility in porous media.

  3. Real-time tracking of dissociation of hyperpolarized 89Y-DTPA: a model for degradation of open-chain Gd3+ MRI contrast agents

    NASA Astrophysics Data System (ADS)

    Ferguson, Sarah; Niedbalski, Peter; Parish, Christopher; Kiswandhi, Andhika; Kovacs, Zoltan; Lumata, Lloyd

    Gadolinium (Gd) complexes are widely used relaxation-based clinical contrast agents in magnetic resonance imaging (MRI). Gd-based MRI contrast agents with open-chain ligand such as Gd-DTPA, commercially known as magnevist, are less stable compared to Gd complexes with macrocyclic ligands such as GdDOTA (Dotarem). The dissociation of Gd-DPTA into Gd ion and DTPA ligand under certain biological conditions such as high zinc levels can potentially cause kidney damage. Since Gd is paramagnetic, direct NMR detection of the Gd-DTPA dissociation is quite challenging due to ultra-short relaxation times. In this work, we have investigated Y-DTPA as a model for Gd-DPTA dissociation under high zinc content solutions. Using dissolution dynamic nuclear polarization (DNP), the 89Y NMR signal is amplified by several thousand-fold. Due to the the relatively long T1 relaxation time of 89Y which translates to hyperpolarization lifetime of several minutes, the dissociation of Y-DTPA can be tracked in real-time by hyperpolarized 89Y NMR spectroscopy. Dissociation kinetic rates and implications on the degradation of open-chain Gd3+ MRI contrast agents will be discussed. This work was supported by the U.S. Department of Defense Award Number W81XWH-14-1-0048 and by the Robert A. Welch Foundation research Grant Number AT-1877.

  4. Heat transfer models for predicting Salmonella enteritidis in shell eggs through supply chain distribution.

    PubMed

    Almonacid, S; Simpson, R; Teixeira, A

    2007-11-01

    Egg and egg preparations are important vehicles for Salmonella enteritidis infections. The influence of time-temperature becomes important when the presence of this organism is found in commercial shell eggs. A computer-aided mathematical model was validated to estimate surface and interior temperature of shell eggs under variable ambient and refrigerated storage temperature. A risk assessment of S. enteritidis based on the use of this model, coupled with S. enteritidis kinetics, has already been reported in a companion paper published earlier in JFS. The model considered the actual geometry and composition of shell eggs and was solved by numerical techniques (finite differences and finite elements). Parameters of interest such as local (h) and global (U) heat transfer coefficient, thermal conductivity, and apparent volumetric specific heat were estimated by an inverse procedure from experimental temperature measurement. In order to assess the error in predicting microbial population growth, theoretical and experimental temperatures were applied to a S. enteritidis growth model taken from the literature. Errors between values of microbial population growth calculated from model predicted compared with experimentally measured temperatures were satisfactorily low: 1.1% and 0.8% for the finite difference and finite element model, respectively. PMID:18034720

  5. FAD oxidizes the ERO1-PDI electron transfer chain: The role of membrane integrity

    SciTech Connect

    Papp, Eszter; Nardai, Gabor; Mandl, Jozsef; Banhegyi, Gabor; Csermely, Peter . E-mail: csermely@puskin.sote.hu

    2005-12-16

    The molecular steps of the electron transfer in the endoplasmic reticulum from the secreted proteins during their oxidation are relatively unknown. We present here that flavine adenine dinucleotide (FAD) is a powerful oxidizer of the oxidoreductase system, Ero1 and PDI, besides the proteins of rat liver microsomes and HepG2 hepatoma cells. Inhibition of FAD transport hindered the action of FAD. Microsomal membrane integrity was mandatory for all FAD-related oxidation steps downstream of Ero1. The PDI inhibitor bacitracin could inhibit FAD-mediated oxidation of microsomal proteins and PDI, but did not hinder the FAD-driven oxidation of Ero1. Our data demonstrated that Ero1 can utilize FAD as an electron acceptor and that FAD-driven protein oxidation goes through the Ero1-PDI pathway and requires the integrity of the endoplasmic reticulum membrane. Our findings prompt further studies to elucidate the membrane-dependent steps of PDI oxidation and the role of FAD in redox folding.

  6. Well-defined coinage metal transfer agents for the synthesis of NHC-based nickel, rhodium and palladium macrocycles.

    PubMed

    Andrew, Rhiann E; Storey, Caroline M; Chaplin, Adrian B

    2016-06-01

    With a view to use as carbene transfer agents, well-defined silver(i) and copper(i) complexes of a macrocyclic NHC-based pincer ligand, bearing a central lutidine donor and a dodecamethylene spacer [CNC-(CH2)12, 1], have been prepared. Although the silver adduct is characterised by X-ray diffraction as a dinuclear species anti-[Ag(μ-1)]2(2+), variable temperature measurements indicate dynamic structural interchange in solution involving fragmentation into mononuclear [Ag(1)](+) on the NMR time scale. In contrast, a mononuclear structure is evident in both solution and the solid-state for the analogous copper adduct partnered with the weakly coordinating [BAr(F)4](-) counter anion. A related copper derivative, bearing instead the more coordinating cuprous bromide dianion [Cu2Br4](2-), is notable for the adoption of an interesting tetranuclear assembly in the solid-state, featuring two cuprophilic interactions and two bridging NHC donors, but is not retained on dissolution. Coinage metal precursors [M(1)]n[BAr(F)4]n (M = Ag, n = 2; M = Cu, n = 1) both act as carbene transfer agents to afford palladium, rhodium and nickel complexes of 1 and the effectiveness of these precursors has been evaluated under equivalent reaction conditions. PMID:27157720

  7. Neutral-Type One-Dimensional Mixed-Valence Halogen-Bridged Platinum Chain Complexes with Large Charge-Transfer Band Gaps.

    PubMed

    Otake, Ken-Ichi; Otsubo, Kazuya; Sugimoto, Kunihisa; Fujiwara, Akihiko; Kitagawa, Hiroshi

    2016-03-01

    One-dimensional (1D) electronic systems have attracted significant attention for a long time because of their various physical properties. Among 1D electronic systems, 1D halogen-bridged mixed-valence transition-metal complexes (the so-called MX chains) have been thoroughly studied owing to designable structures and electronic states. Here, we report the syntheses, structures, and electronic properties of three kinds of novel neutral MX-chain complexes. The crystal structures consist of 1D chains of Pt-X repeating units with (1R,2R)-(-)-diaminocychlohexane and CN(-) in-plane ligands. Because of the absence of a counteranion, the neutral MX chains have short interchain distances, so that strong interchain electronic interaction is expected. Resonance Raman spectra and diffuse-reflectance UV-vis spectra indicate that their electronic states are mixed-valence states (charge-density-wave state: Pt(2+)···X-Pt(4+)-X···Pt(2+)···X-Pt(4+)-X···). In addition, the relationship between the intervalence charge-transfer (IVCT) band gap and the degree of distortion of the 1D chain shows that the neutral MX chains have a larger IVCT band gap than that of cationic MX-chain complexes. These results provide new insight into the physical and electronic properties of 1D chain compounds. PMID:26901774

  8. Bioaccumulation and food-chain analysis for evaluating ecological risks in terrestrial and wetland habitats: Availability-transfer factors (ATFs) in soil {r_arrow} soil macroinvertebrate {r_arrow} amphibian food chains

    SciTech Connect

    Linder, G.; Bollman, M.; Callahan, C.; Gillette, C.; Nebeker, A.; Wilborn, D.

    1998-12-31

    As part of the ecological risk assessment process for terrestrial and wetland habitats, the evaluation of bioaccumulative chemicals of concern (BCCs) is frequently pursued through food-chain analysis with a subsequent comparison of daily doses to benchmark toxicity reference values, when available. Food-chain analysis has frequently been applied to the analysis of exposure to BCCs identified as chemicals of potential ecological concern (COPECs) in the ecological risk assessment process. Here, designed studies focused on wetland food-chains such as hydric soil {r_arrow} soil macroinvertebrate {r_arrow} amphibian and terrestrial food-chains such as soil {r_arrow} plant {r_arrow} small mammal illustrate an approach for the derivation and validation of trophic transfer factors for metals considered as COPECs such as cadmium, chromium, copper, lead, and zinc. The results clearly indicate that the transfer of chemicals between trophic levels is critical in the bioaccumulation process in wetland and terrestrial food-chains and is influenced by numerous interacting abiotic and biotic factors, including physicochemical properties of soil, and the role, if any, that the metal has in the receptor as a required trace element.

  9. Controlling Electron Transfer between the Two Cofactor Chains of Photosystem I by the Redox State of One of Their Components

    PubMed Central

    Santabarbara, Stefano; Bullock, Bradford; Rappaport, Fabrice; Redding, Kevin E.

    2015-01-01

    Two functional electron transfer (ET) chains, related by a pseudo-C2 symmetry, are present in the reaction center of photosystem I (PSI). Due to slight differences in the environment around the cofactors of the two branches, there are differences in both the kinetics of ET and the proportion of ET that occurs on the two branches. The strongest evidence that this is indeed the case relied on the observation that the oxidation rates of the reduced phylloquinone (PhQ) cofactor differ by an order of magnitude. Site-directed mutagenesis of residues involved in the respective PhQ-binding sites resulted in a specific alteration of the rates of semiquinone oxidation. Here, we show that the PsaA-F689N mutation results in an ∼100-fold decrease in the observed rate of PhQA− oxidation. This is the largest change of PhQA− oxidation kinetics observed so far for a single-point mutation, resulting in a lifetime that exceeds that of the terminal electron donor, P700+. This situation allows a second photochemical charge separation event to be initiated before PhQA− has decayed, thereby mimicking in PSI a situation that occurs in type II reaction centers. The results indicate that the presence of PhQA− does not impact the overall quantum yield and leads to an almost complete redistribution of the fractional utilization of the two functional ET chains, in favor of the one that does not bear the charged species. The evolutionary implications of these results are also briefly discussed. PMID:25809266

  10. Controlling electron transfer between the two cofactor chains of photosystem I by the redox state of one of their components.

    PubMed

    Santabarbara, Stefano; Bullock, Bradford; Rappaport, Fabrice; Redding, Kevin E

    2015-03-24

    Two functional electron transfer (ET) chains, related by a pseudo-C2 symmetry, are present in the reaction center of photosystem I (PSI). Due to slight differences in the environment around the cofactors of the two branches, there are differences in both the kinetics of ET and the proportion of ET that occurs on the two branches. The strongest evidence that this is indeed the case relied on the observation that the oxidation rates of the reduced phylloquinone (PhQ) cofactor differ by an order of magnitude. Site-directed mutagenesis of residues involved in the respective PhQ-binding sites resulted in a specific alteration of the rates of semiquinone oxidation. Here, we show that the PsaA-F689N mutation results in an ∼100-fold decrease in the observed rate of PhQA(-) oxidation. This is the largest change of PhQA(-) oxidation kinetics observed so far for a single-point mutation, resulting in a lifetime that exceeds that of the terminal electron donor, P700(+). This situation allows a second photochemical charge separation event to be initiated before PhQA(-) has decayed, thereby mimicking in PSI a situation that occurs in type II reaction centers. The results indicate that the presence of PhQA(-) does not impact the overall quantum yield and leads to an almost complete redistribution of the fractional utilization of the two functional ET chains, in favor of the one that does not bear the charged species. The evolutionary implications of these results are also briefly discussed. PMID:25809266

  11. Employing Tryptone as a General Phase Transfer Agent to Produce Renal Clearable Nanodots for Bioimaging.

    PubMed

    Liu, Fuyao; He, Xiuxia; Zhang, Junping; Zhang, Huimao; Wang, Zhenxin

    2015-08-12

    Hydrophobic ultrasmall nanoparticles synthesized in nonpolar solvents exhibit great potential in biomedical applications. However, a major challenge when applying these nanomaterials in biomedical research is the lack of a versatile strategy to render them water dispersible while preserving the hydrodynamic diameter (HD) to be less than 8 nm for efficient renal clearance. To address this problem, tryptone is employed as the novel ligand to fabricate a simple, versatile, and inexpensive strategy for transferring hydrophobic NaGdF(4) nanodots (3 nm in diameter) from organic phase into aqueous phase without any complicated organic synthesis. The paramagnetic properties of NaGdF(4) nanodots are well retained after the phase transfer process. In particular, the tryptone-NaGdF(4) nanodots have ultrasmall HD (ca., 7.5 nm), which greatly improves their tumor accumulation and facilitates renal clearance within 24 h postinjection. The as-prepared tryptone-NaGdF(4) nanodots can also be further functionalized with other molecules for extensively biomedical and bioanalytical applications. Furthermore, the proposed strategy can easily be extended to transfer other types of inorganic nanoparticles from hydrophobic to hydrophilic for facilitating biomedical applications. PMID:25914195

  12. Investigations in physical mechanism of the oxidative desulfurization process assisted simultaneously by phase transfer agent and ultrasound.

    PubMed

    Bhasarkar, Jaykumar B; Chakma, Sankar; Moholkar, Vijayanand S

    2015-05-01

    This paper attempts to discern the physical mechanism of the oxidative desulfurization process simultaneously assisted by ultrasound and phase transfer agent (PTA). With different experimental protocols, an attempt is made to deduce individual beneficial effects of PTA and ultrasound on the oxidative desulfurization system, and also the synergy between the effects of PTA and ultrasound. Effect of PTA is more marked for mechanically stirred system due to mass transfer limitations, while intense emulsification due to ultrasound helps overcome the mass transfer limitations and reduces the extent of enhancement of oxidation by PTA. Despite application of PTA and ultrasound, the intrinsic factors and properties of the reactants such as polarity (and hence partition coefficient) and diffusivity have a crucial effect on the extent of oxidation. The intrinsic reactivity of the oxidant also plays a vital role, as seen from the extent of oxidation achieved with performic acid and peracetic acid. The interfacial transport of oxidant in the form of oxidant-PTA complex reduces the undesired consumption of oxidant by the reducing species formed during transient cavitation in organic medium, which helps effective utilization of oxidant towards desulfurization. PMID:25465876

  13. Metal Ion-dependent Heavy Chain Transfer Activity of TSG-6 Mediates Assembly of the Cumulus-Oocyte Matrix.

    PubMed

    Briggs, David C; Birchenough, Holly L; Ali, Tariq; Rugg, Marilyn S; Waltho, Jon P; Ievoli, Elena; Jowitt, Thomas A; Enghild, Jan J; Richter, Ralf P; Salustri, Antonietta; Milner, Caroline M; Day, Anthony J

    2015-11-27

    The matrix polysaccharide hyaluronan (HA) has a critical role in the expansion of the cumulus cell-oocyte complex (COC), a process that is necessary for ovulation and fertilization in most mammals. Hyaluronan is organized into a cross-linked network by the cooperative action of three proteins, inter-α-inhibitor (IαI), pentraxin-3, and TNF-stimulated gene-6 (TSG-6), driving the expansion of the COC and providing the cumulus matrix with its required viscoelastic properties. Although it is known that matrix stabilization involves the TSG-6-mediated transfer of IαI heavy chains (HCs) onto hyaluronan (to form covalent HC·HA complexes that are cross-linked by pentraxin-3) and that this occurs via the formation of covalent HC·TSG-6 intermediates, the underlying molecular mechanisms are not well understood. Here, we have determined the tertiary structure of the CUB module from human TSG-6, identifying a calcium ion-binding site and chelating glutamic acid residue that mediate the formation of HC·TSG-6. This occurs via an initial metal ion-dependent, non-covalent, interaction between TSG-6 and HCs that also requires the presence of an HC-associated magnesium ion. In addition, we have found that the well characterized hyaluronan-binding site in the TSG-6 Link module is not used for recognition during transfer of HCs onto HA. Analysis of TSG-6 mutants (with impaired transferase and/or hyaluronan-binding functions) revealed that although the TSG-6-mediated formation of HC·HA complexes is essential for the expansion of mouse COCs in vitro, the hyaluronan-binding function of TSG-6 does not play a major role in the stabilization of the murine cumulus matrix. PMID:26468290

  14. Metal Ion-dependent Heavy Chain Transfer Activity of TSG-6 Mediates Assembly of the Cumulus-Oocyte Matrix*

    PubMed Central

    Briggs, David C.; Birchenough, Holly L.; Ali, Tariq; Rugg, Marilyn S.; Waltho, Jon P.; Ievoli, Elena; Jowitt, Thomas A.; Enghild, Jan J.; Richter, Ralf P.; Salustri, Antonietta; Milner, Caroline M.; Day, Anthony J.

    2015-01-01

    The matrix polysaccharide hyaluronan (HA) has a critical role in the expansion of the cumulus cell-oocyte complex (COC), a process that is necessary for ovulation and fertilization in most mammals. Hyaluronan is organized into a cross-linked network by the cooperative action of three proteins, inter-α-inhibitor (IαI), pentraxin-3, and TNF-stimulated gene-6 (TSG-6), driving the expansion of the COC and providing the cumulus matrix with its required viscoelastic properties. Although it is known that matrix stabilization involves the TSG-6-mediated transfer of IαI heavy chains (HCs) onto hyaluronan (to form covalent HC·HA complexes that are cross-linked by pentraxin-3) and that this occurs via the formation of covalent HC·TSG-6 intermediates, the underlying molecular mechanisms are not well understood. Here, we have determined the tertiary structure of the CUB module from human TSG-6, identifying a calcium ion-binding site and chelating glutamic acid residue that mediate the formation of HC·TSG-6. This occurs via an initial metal ion-dependent, non-covalent, interaction between TSG-6 and HCs that also requires the presence of an HC-associated magnesium ion. In addition, we have found that the well characterized hyaluronan-binding site in the TSG-6 Link module is not used for recognition during transfer of HCs onto HA. Analysis of TSG-6 mutants (with impaired transferase and/or hyaluronan-binding functions) revealed that although the TSG-6-mediated formation of HC·HA complexes is essential for the expansion of mouse COCs in vitro, the hyaluronan-binding function of TSG-6 does not play a major role in the stabilization of the murine cumulus matrix. PMID:26468290

  15. Structural geometry and kinematic processes at the intracontinental Daloushan mountain chain: Implications for tectonic transfer in the Yangtze Block interior

    NASA Astrophysics Data System (ADS)

    Deng, Bin; Li, Zhi-Wu; Liu, Shu-Gen; Wang, Guo-Zhi; Li, Shuang-Jian; Qin, Zuo-Pen; Li, Jing-Xi; Jansa, Luba

    2016-02-01

    The Daloushan mountain chain, located in the centre of the upper Yangtze continental block, is considered to represent the locus of the tectonic shortening resulting from the eastward growth of the Tibetan Plateau and NW-thrusting of the Xuefeng Orogen. Structural data and apatite fission-track ages have been used to decipher the geometry and the kinematic evolution of the Daloushan. The latter is subdivided into two domains: the eastern domain, governed by west- to NW-verging thrusting and deformation with dextral transpression, and a western domain, governed by south-verging thrusting and deformation. Both domains experienced four episodes of deformation, synchronous with the four stages of post-Cretaceous denudation, marked by rapid cooling propagating eastward from 20 to 5 Ma, at a rate of ∼0.1 mm/year. In particular, the last two episodes of denudation are closely related to the growth of the Tibetan Plateau. This indicates an intra-continental transfer of tectonic forcing from the Palaeo-Pacific to the Tethys-Himalayan Tectonic Domain across the Daloushan.

  16. Markov Chain Method for Radiative Transfer Modeling: A Case Study of Aerosol/Surface Retrieval using AirMSPI Measurements

    NASA Astrophysics Data System (ADS)

    Xu, F.; Diner, D. J.; Davis, A. B.; Latyshev, S.; Garay, M. J.; Kalashnikova, O.; Ge, C.; Wang, J.

    2013-12-01

    A vector Markov chain (MarCh) radiative transfer (RT) code developed at JPL that includes forward modeling of radiance and polarization fields and linearization (analytical estimation of Jacobians) was incorporated into an aerosol and surface retrieval package for a plane-parallel atmosphere/surface system. The RT computation by MarCh is based on matrix operations. To improve the code's computational efficiency, the forward model is currently undergoing acceleration through the exploration of different strategies for matrix operation and inversion, including numerical optimization, multi-threading/multi-processing techniques on a CPU. Implementation on a graphics processing unit (GPU) is also planned. Following a benchmarking study of the forward model, the performance of MarCh in aerosol and surface retrieval is being tested. With an optimized algorithm, we started from aerosol optical depth and surface retrieval using imagery acquired by Airborne Multiangle SpectroPolarimetric Imager (AirMSPI) over Fresno, CA. Aerosol properties including concentration and size distribution of different species provided by the Weather Research and Forecasting (WRF)-Chem model were used to constrain the retrieval and reduce the parameter space. The assumptions of spectral invariance in the angular shape of surface bidirectional reflectance factors (BRFs) and the magnitude of polarized surface BRFs were tested. The aerosol and surface properties are then relaxed in a stepwise way to refine the aerosol retrieval results and enable comparison with independent retrievals obtained from a collocated AErosol RObotic NETwork (AERONET) station.

  17. A hermetic self-sustained microbial solar cell based on Chlorella vulgaris and a versatile charge transfer chain

    NASA Astrophysics Data System (ADS)

    Pan, Keliang; Zhou, Peijiang

    2015-10-01

    A hermetic noble-metal-free membrane-less microbial solar cell (MSC) is established. The substances decomposition and regeneration in this MSC are carried out only by Chlorella vulgaris simultaneously. The conversion of metabolism types of C. vulgaris is controlled only by illumination. By using a pleiotropic redox mediator and a cupric hexacyanoferrate modified cathode, a two-phase three-stage charge transfer chain is formed. Through this pathway, the one microorganism self-sustained system gets a long-term power output up to 0.04773 mW/cm2 at 0.423 V without any material exchange with external, which is 50 times higher than that obtained from the original system. Benefiting from this electron buffer system, the battery will achieve an electricity generation in both light and dark conditions. There is almost no consumption of any substrates throughout the stabilized process, and no more additions are required. This maintenance-free and extremely inexpensive reactor with a simple structure and a long service life demonstrates the possibility of combining the microbial, chemical and photo cells.

  18. Xanthohumol induces generation of reactive oxygen species and triggers apoptosis through inhibition of mitochondrial electron transfer chain complex I.

    PubMed

    Zhang, Bo; Chu, Wei; Wei, Peng; Liu, Ying; Wei, Taotao

    2015-12-01

    Xanthohumol is a prenylflavonoid extracted from hops (Humulus lupulus). It possesses anti-cancer and anti-inflammatory activities in vitro and in vivo, and offers therapeutic benefits for treatment of metabolic syndromes. However, the precise mechanisms underlying its pharmacological effects remain to be elucidated, together with its cellular target. Here, we provide evidence that xanthohumol directly interacts with the mitochondrial electron transfer chain complex I (NADH dehydrogenase), inhibits the oxidative phosphorylation, triggers the production of reactive oxygen species, and induces apoptosis. In addition, we show that as a result of the inhibition of the mitochondrial oxidative phosphorylation, xanthohumol exposure causes a rapid decrease of mitochondrial transmembrane potential. Furthermore, we showed that xanthohumol up-regulates the glycolytic capacity in cells, and thus compensates cellular ATP generation. Dissection of the multiple steps of aerobic respiration by extracellular flux assays revealed that xanthohumol specifically inhibits the activity of mitochondrial complex I, but had little effect on that of complex II, III and IV. Inhibition of complex I by xanthohumol caused the overproduction of reactive oxygen species, which are responsible for the induction of apoptosis in cancer cells. We also found that isoxanthohumol, the structural isomer of xanthohumol, is inactive to cells, suggesting that the reactive 2-hydroxyl group of xanthohumol is crucial for its targeting to the mitochondrial complex I. Together, the remodeling of cell metabolism revealed here has therapeutic potential for the use of xanthohumol. PMID:26453927

  19. A Cu(II)2 Paramagnetic Chemical Exchange Saturation Transfer Contrast Agent Enabled by Magnetic Exchange Coupling.

    PubMed

    Du, Kang; Harris, T David

    2016-06-29

    The ability of magnetic exchange coupling to enable observation of paramagnetic chemical exchange saturation transfer (PARACEST) in transition metal ions with long electronic relaxation times (τs) is demonstrated. Metalation of the dinucleating, tetra(carboxamide) ligand HL with Cu(2+) in the presence of pyrophosphate (P2O7)(4-) affords the complex [LCu(II)2(P2O7)](-). Solution-phase variable-temperature magnetic susceptibility data reveal weak ferromagnetic superexchange coupling between the two S = 1/2 Cu(II) centers, with a coupling constant of J = +2.69(5) cm(-1), to give an S = 1 ground state. This coupling results in a sharpened NMR line width relative to a GaCu analogue, indicative of a shortening of τs. Presaturation of the amide protons in the Cu2 complex at 37 °C leads to a 14% intensity decrease in the bulk water (1)H NMR signal through the CEST effect. Conversely, no CEST effect is observed in the GaCu complex. These results provide the first example of a Cu-based PARACEST magnetic resonance contrast agent and demonstrate the potential to expand the metal ion toolbox for PARACEST agents through introduction of magnetic exchange coupling. PMID:27276533

  20. Gas-phase transfer of polymer cross-linking agents and by-products to solid oral pharmaceuticals.

    PubMed

    Maus, Russell G; Li, Min; Clement, Christopher M; Kinzer, Jeffery A

    2007-11-01

    In the pharmaceutical industry, solid oral compressed tablets (OCT) are frequently transported in bulk containers prior to packaging. While in this state, the product is generally protected from interaction with liquid and solid contaminants by physical barriers (e.g., polyethylene bags, drums, etc.). Vapor phase contamination, although generally less frequently observed, is possible. A specific example of the detection and identification of volatile by-products (acetophenone and 2-phenyl-2-propanol) of a common polymer cross-linking agent (dicumyl peroxide) is presented. The product tablets were compressed, placed into double polyethylene bags, and subsequently placed into a polyethylene drum for shipment overseas. To cushion the product during transit, a cross-linked polyethylene foam disk (designed to fit into the bottom of the drum) was placed below the bag of tablets. Initially, these contaminants were detected by HPLC with UV detection at the receiving laboratory, and assumed to be degradates of the active components of the product. Further analysis showed that neither the collected UV absorbance data nor the observed levels of the contaminants were consistent with known degradates of the product. Liquid extraction followed by GC-MS analysis of the product as well as the cross-linked foam disk exhibited measurable quantities of the contaminants in question. Vapor phase transfer of these cross-linking agent by-products, originating in the cross-linked foam pads, was determined to be the root cause for the presence of these compounds in the product. PMID:17686599

  1. Study of fluorescence characteristics of the charge-transfer reaction of quinolone agents with bromanil

    NASA Astrophysics Data System (ADS)

    Li, Wen-Ying; Chen, Xiao-Fang; Xuan, Chun-Sheng

    2009-01-01

    A spectrofluorimetric method was discussed for the determination of three antibacterial quinolone derivatives, ofloxacin (OFL), norfloxacin (NOR) and ciprofloxacin (CIP) through charge-transfer complexation (CTC) with 2,3,5,6-tetrabromo-1,4-benzoquinone (bromanil, TBBQ). The method was based on the reaction of these drugs as n-electron donors with the π-acceptor TBBQ. TBBQ was found to react with these drugs to produce a kind of yellow complexes and the fluorescence intensities of the complexes were enhanced by 29-36 times more than those of the corresponding monomers. UV-vis, 1H NMR and XPS techniques were used to study the complexes formed. The various experimental parameters affecting the fluorescence intensity were studied and optimized. Under optimal reaction conditions, the rectilinear calibration graphs were obtained in the concentration range of 0.021-2.42 μg mL -1, 0.017-2.63 μg mL -1 and 0.019-2.14 μg mL -1 for OFL, NOR and CIP, respectively. The methods developed were applied successfully to the determination of the subject drugs in their pharmaceutical dosage forms with good precision and accuracy compared to official and reported methods as revealed by t- and F-tests.

  2. Main-Chain and Side-Chain Sequence-Regulated Vinyl Copolymers by Iterative Atom Transfer Radical Additions and 1:1 or 2:1 Alternating Radical Copolymerization.

    PubMed

    Soejima, Takamasa; Satoh, Kotaro; Kamigaito, Masami

    2016-01-27

    Main- and side-chain sequence-regulated vinyl copolymers were prepared by a combination of iterative atom transfer radical additions (ATRAs) of vinyl monomers for side-chain control and 1:1 or 2:1 alternating radical copolymerization of the obtained side-chain sequenced "oligomonomers" and vinyl comonomers for main-chain control. A complete set of sequence-regulated trimeric vinyl oligomers of styrene (S) and/or methyl acrylate (A) were first synthesized via iterative ATRAs of these monomers to a halide of monomeric S or A unit (X-S or X-A) under optimized conditions with appropriate ruthenium or copper catalysts, which were selected depending on the monomers and halides. The obtained halogen-capped oligomers were then converted into a series of maleimide (M)-ended oligomonomers with different monomer compositions and sequences (M-SSS, M-ASS, M-SAS, M-AAS, M-SSA, M-ASA, M-SAA, M-AAA) by a substitution reaction of the halide with furan-protected maleimide anion followed by deprotection of the furan units. These maleimide-ended oligomonomers were then radically copolymerized with styrene or limonene to enable the 1:1 or 2:1 monomer-sequence regulation in the main chain and finally result in the main- and side-chain sequence-regulated vinyl copolymers with high molecular weights in high yield. The properties of the sequence-regulated vinyl copolymers depended on not only the monomer compositions but also the monomer sequences. The solubility was highly affected by the outer monomer units in the side chains whereas the glass transition temperatures were primarily affected by the two successive monomer sequences. PMID:26761148

  3. Novel Dental Restorative Materials having Low Polymerization Shrinkage Stress via Stress Relaxation by Addition-Fragmentation Chain Transfer

    PubMed Central

    Park, Hee Young; Kloxin, Christopher J.; Abuelyaman, Ahmed S.; Oxman, Joe D.; Bowman, Christopher N.

    2012-01-01

    Objectives To produce a reduced stress dental restorative material while simultaneously maintaining excellent mechanical properties, we have incorporated an allyl sulfide functional group into norbornene-methacrylate comonomer resins. We hypothesize that the addition-fragmentation chain transfer (AFCT) enabled by the presence of the allyl sulfide relieves stress in these methacrylate-based systems while retaining excellent mechanical properties owing to the high glass transition temperature of norbornene-containing resins. Methods An allyl sulfide-containing dinorbornene was stoichiometrically formulated with a ring-containing allyl sulfide-possessing methacrylate. To evaluate the stress relaxation effect as a function of the allyl sulfide concentration, a propyl sulfide-based dinorbornene, not capable of addition-fragmentation, was also formulated with the methacrylate monomer. Shrinkage stress, the glass transition temperature and the elastic modulus were all measured. The composite flexural strength and modulus were also measured. ANOVA (CI 95%) was conducted to determine differences between the means. Results Increasing the allyl sulfide content in the resin dramatically reduces the final stress in the norbornene-methacrylate systems. Both norbornene-methacrylate resins demonstrated almost zero stress (more than 96% stress reduction) compared with the conventional BisGMA/TEGDMA 70/30 wt% control. Mechanical properties of the allyl sulfide-based dental composites were improved to the point of being statistically indistinguishable from the control BisGMA-TEGDMA by changing the molar ratio between the methacrylate and norbornene functionalities. Significance The allyl sulfide-containing norbornene-methacrylate networks possessed super-ambient Tg, and demonstrated significantly lower shrinkage stress when compared with the control (BisGMA/TEGDMA 70 to 30 wt%). Although additional development remains, these low stress materials exhibit excellent mechanical

  4. Case studies of aerosol and ocean color retrieval using a Markov chain radiative transfer model and AirMSPI measurements

    NASA Astrophysics Data System (ADS)

    Xu, F.; Diner, D. J.; Seidel, F. C.; Dubovik, O.; Zhai, P.

    2014-12-01

    A vector Markov chain radiative transfer method was developed for forward modeling of radiance and polarization fields in a coupled atmosphere-ocean system. The method was benchmarked against an independent Successive Orders of Scattering code and linearized through the use of Jacobians. Incorporated with the multi-patch optimization algorithm and look-up-table method, simultaneous aerosol and ocean color retrievals were performed using imagery acquired by the Airborne Multiangle SpectroPolarimetric Imager (AirMSPI) when it was operated in step-and-stare mode with 9 viewing angles ranging between ±67°. Data from channels near 355, 380, 445, 470*, 555, 660*, and 865* nm were used in the retrievals, where the asterisk denotes the polarimetric bands. Retrievals were run for AirMSPI overflights over Southern California and Monterey Bay, CA. For the relatively high aerosol optical depth (AOD) case (~0.28 at 550 nm), the retrieved aerosol concentration, size distribution, water-leaving radiance, and chlorophyll concentration were compared to those reported by the USC SeaPRISM AERONET-OC site off the coast of Southern California on 6 February 2013. For the relatively low AOD case (~0.08 at 550 nm), the retrieved aerosol concentration and size distribution were compared to those reported by the Monterey Bay AERONET site on 28 April 2014. Further, we evaluate the benefits of multi-angle and polarimetric observations by performing the retrievals using (a) all view angles and channels; (b) all view angles but radiances only (no polarization); (c) the nadir view angle only with both radiance and polarization; and (d) the nadir view angle without polarization. Optimized retrievals using different initial guesses were performed to provide a measure of retrieval uncertainty. Removal of multi-angular or polarimetric information resulted in increases in both parameter uncertainty and systematic bias. Potential accuracy improvements afforded by applying constraints on the surface

  5. Chemiluminescence resonance energy transfer imaging on magnetic particles for single-nucleotide polymorphism detection based on ligation chain reaction.

    PubMed

    Bi, Sai; Zhang, Zhipeng; Dong, Ying; Wang, Zonghua

    2015-03-15

    A novel ligation chain reaction (LCR) methodology for single-nucleotide polymorphism (SNP) detection was developed based on luminol-H2O2-horseradish peroxidase (HRP)-mimicking DNAzyme-fluorescein chemiluminescence resonance energy transfer (CRET) imaging on magnetic particles. For LCR, four unique target-complement probes (X and X(⁎), YG and Y(⁎)) for the amplification of K-ras (G12C) were designed by modifying G-quadruplex sequence at 3'-end of YG and fluorescein at 5'-end of Y(⁎). After the LCR, the resulting products of XYG/X(⁎)Y(⁎) with biotin-labeled X(⁎) were captured onto streptavidin-coated magnetic particles (SA-MPs) via specific biotin-SA interaction, which stimulated the CRET reaction from hemin/G-quadruplex-catalyzed luminol-H2O2 CL system to fluorescein. By collecting signals by a cooled low-light CCD, a CRET imaging method was proposed for visual detection and quantitative analysis of SNP. As low as 0.86fM mutant DNA was detected by this assay, and positive mutation detection was achieved with a wild-type to mutant ratio of 10,000:1. This high sensitivity and specificity could be attributed to not only the exponential amplification and excellent discrimination of LCR but also the employment of SA-MPs. SA-MPs ensured the feasibility of the proposed strategy, which also simplified the operations through magnetic separation and separated the reaction and detection procedures to improve sensitivity. The proposed LCR-CRET imaging strategy extends the application of signal amplification techniques to SNP detection, providing a promising platform for effective and high-throughput genetic diagnosis. PMID:25461149

  6. Synthesis of five and six-membered heterocycles bearing an arylpiperazinylalkyl side chain as orally active antinociceptive agents.

    PubMed

    Vergelli, Claudia; Ciciani, Giovanna; Cilibrizzi, Agostino; Crocetti, Letizia; Di Cesare Mannelli, Lorenzo; Ghelardini, Carla; Guerrini, Gabriella; Iacovone, Antonella; Giovannoni, Maria Paola

    2015-10-01

    A number of heterocycles bearing an arylpiperazinylalkyl side chain and structurally related to the previously described lead ET1 (4-amino-6-methyl-2-[3-(4-p-tolylpiperazin-1-yl)propyl]-5-vinylpyridazin-3(2H)-one) was synthesized and tested for their antinociceptive activity in Writhing Test. Many compounds, tested at doses of 20-40 mg/kg po were able to reduce the number of abdominal constrictions by more than 47% and, in same cases, the potency is comparable to lead ET1 as for 5e, 24a, 27b and 27c. The analgesia induced by the active compounds was completely prevented by pretreatment with α2-antagonist yohimbine, confirming the involvement of the adrenergic system in the mechanism of action for these new compounds. PMID:26361735

  7. Simultaneous detection of seven sexually transmitted agents in human immunodeficiency virus-infected Brazilian women by multiplex polymerase chain reaction.

    PubMed

    Souza, Raquel P; de Abreu, André L P; Ferreira, Érika C; Rocha-Brischiliari, Sheila C; de B Carvalho, Maria D; Pelloso, Sandra M; Bonini, Marcelo G; Gimenes, Fabrícia; Consolaro, Marcia E L

    2013-12-01

    We determined the prevalence of seven clinically important pathogens that cause sexually transmitted infections (STIs) (Chlamydia trachomatis, Neisseria gonorrhoeae, Mycoplasma genitalium, Trichomonas vaginalis, herpes simplex virus 1 [HSV-1], HSV-2, and Treponema pallidum), by using a multiplex polymerase chain reaction (M-PCR) in samples from Brazilian woman infected with human immunodeficiency virus 1 (HIV-1) and uninfected Brazilian women (controls). The M-PCR assay identified all STIs tested for and surprisingly, occurred association between the control and STIs. This association was probably caused by excellent HIV infection control and regular monitoring in these women established by public health strategies in Brazil to combat HIV/acquired immunodeficiency syndrome. Studies using this M-PCR in different populations may help to better elucidate the roles of STIs in several conditions. PMID:24080632

  8. Trophic transfer of lead through a model marine four-level food chain: Tetraselmis suecica, Artemia franciscana, Litopenaeus vannamei, and Haemulon scudderi.

    PubMed

    Soto-Jiménez, M F; Arellano-Fiore, C; Rocha-Velarde, R; Jara-Marini, M E; Ruelas-Inzunza, J; Páez-Osuna, F

    2011-08-01

    The objective of this investigation was to assess the transfer of lead (Pb) along an experimental, four-level food chain: Tetraselmis suecica (phytoplankton) → Artemia franciscana (crustacean, brine shrimp) → Litopenaeus vannamei (crustacean, white shrimp) → Haemulon scudderi (fish, grunt). T. suecica was exposed to a sublethal dose of Pb in solution and then used as the base of a marine food chain. Significant differences in Pb concentrations were found between exposed organisms of the different trophic levels and the control. Particularly, Pb concentrations in fish of the simulated trophic chain were two-to three times higher in the exposed specimens than in the control. Levels of Pb in phytoplankton showed a substantial increase with respect to the solution (level I), with bioconcentration factors averaging from 930 to 3630. In contrast, a strong decrease in Pb concentration from phytoplankton to zooplankton (level II) and from zooplankton to shrimp tissues (level III) was evidenced by bioaccumulation factors <1. Despite the decrease in the assimilation efficiency of metal transfer observed in these two predators, Pb concentration in the grunt fish (level IV) was higher than in the shrimp (level III) (bioaccumulation factor >1.0). Some of the added Pb is transferred from the phytoplankton along the food chain, thus producing a net accumulation of Pb mainly in fish and, to a lesser extent, in shrimp tissues. Because Pb is one of the most pervasive contaminants in coastal ecosystems, its transference by way of diet and potential net accumulation in higher predators is of ecologic importance for marine life. In addition, because shrimp and adult Haemulon scudderi are commercially important resources, this issue is of particular relevance to the safety of marine products. PMID:21082317

  9. Development of a set of multiplex standard polymerase chain reaction assays for the identification of infectious agents from aborted bovine clinical samples.

    PubMed

    Tramuta, Clara; Lacerenza, Daniela; Zoppi, Simona; Goria, Mariella; Dondo, Alessandro; Ferroglio, Ezio; Nebbia, Patrizia; Rosati, Sergio

    2011-07-01

    The current study describes the development of a set of 5 multiplex polymerase chain reaction (mPCR) assays for the simultaneous detection of abortive infection agents in bovine fetal tissues, including Brucella spp., Leptospira spp., and Campylobacter fetus (mPCR1); Hammondia heydorni, Neospora caninum, and Toxoplasma gondii (mPCR2); Coxiella burnetii and Chlamydophila psittaci (mPCR3); Mycoplasma bovis, Mycoplasma bovigenitalium, and Ureaplasma diversum (mPCR4); and Bovine viral diarrhea virus (BVDV) and Bovine herpesvirus-1 (BoHV-1; mPCR5). The protocol was tested on different tissue samples collected from 50 aborted bovine fetuses, and it showed that out of the 50 fetuses, 7 (14%, mPCR2) were PCR-positive for N. caninum, 4 (8%, mPCR5) were PCR-positive for BVDV, and 2 (4%, mPCR4) were PCR-positive for U. diversum. The results obtained by using each multiplex PCR were 100% concordant with those obtained by using the respective PCR assays targeting single genes on the same specimens. Moreover, all multiplex PCR assays on clinical samples were compared with reference methods, obtaining a perfect accordance in all samples and confirming the validity of the set of multiplex PCR assays. The proposed set of multiplex PCR assays is, therefore, suitable for the simultaneous detection of the main infectious agents responsible for bovine abortion. PMID:21908306

  10. Nucleic Acid Ligands With Protein-like Side Chains: Modified Aptamers and Their Use as Diagnostic and Therapeutic Agents

    PubMed Central

    Rohloff, John C; Gelinas, Amy D; Jarvis, Thale C; Ochsner, Urs A; Schneider, Daniel J; Gold, Larry; Janjic, Nebojsa

    2014-01-01

    Limited chemical diversity of nucleic acid libraries has long been suspected to be a major constraining factor in the overall success of SELEX (Systematic Evolution of Ligands by EXponential enrichment). Despite this constraint, SELEX has enjoyed considerable success over the past quarter of a century as a result of the enormous size of starting libraries and conformational richness of nucleic acids. With judicious introduction of functional groups absent in natural nucleic acids, the “diversity gap” between nucleic acid–based ligands and protein-based ligands can be substantially bridged, to generate a new class of ligands that represent the best of both worlds. We have explored the effect of various functional groups at the 5-position of uracil and found that hydrophobic aromatic side chains have the most profound influence on the success rate of SELEX and allow the identification of ligands with very low dissociation rate constants (named Slow Off-rate Modified Aptamers or SOMAmers). Such modified nucleotides create unique intramolecular motifs and make direct contacts with proteins. Importantly, SOMAmers engage their protein targets with surfaces that have significantly more hydrophobic character compared with conventional aptamers, thereby increasing the range of epitopes that are available for binding. These improvements have enabled us to build a collection of SOMAmers to over 3,000 human proteins encompassing major families such as growth factors, cytokines, enzymes, hormones, and receptors, with additional SOMAmers aimed at pathogen and rodent proteins. Such a large and growing collection of exquisite affinity reagents expands the scope of possible applications in diagnostics and therapeutics. PMID:25291143

  11. Concise and Efficient Fluorescent Probe via an Intromolecular Charge Transfer for the Chemical Warfare Agent Mimic Diethylchlorophosphate Vapor Detection.

    PubMed

    Yao, Junjun; Fu, Yanyan; Xu, Wei; Fan, Tianchi; Gao, Yixun; He, Qingguo; Zhu, Defeng; Cao, Huimin; Cheng, Jiangong

    2016-02-16

    Sarin, used as chemical warfare agents (CWAs) for terrorist attacks, can induce a number of virulent effects. Therefore, countermeasures which could realize robust and convenient detection of sarin are in exigent need. A concise charge-transfer colorimetric and fluorescent probe (4-(6-(tert-butyl)pyridine-2-yl)-N,N-diphenylaniline, TBPY-TPA) that could be capable of real-time and on-site monitoring of DCP vapor was reported in this contribution. Upon contact with DCP, the emission band red-shifted from 410 to 522 nm upon exposure to DCP vapor. And the quenching rate of TBPY-TPA reached up to 98% within 25 s. Chemical substances such as acetic acid (HAc), dimethyl methylphosphonate (DMMP), pinacolyl methylphosphonate (PAMP), and triethyl phosphate (TEP) do not interfere with the detection. A detection limit for DCP down to 2.6 ppb level is remarkably achieved which is below the Immediately Dangerous to Life or Health concentration. NMR data suggested that a transformation of the pyridine group into pyridinium salt via a cascade reaction is responsible for the sensing process which induced the dramatic fluorescent red shift. All of these data suggest TBPY-TPA is a promising fluorescent sensor for a rapid, simple, and low-cost method for DCP detection, which could be easy to prepare as a portable chemosensor kit for its practical application in real-time and on-site monitoring. PMID:26776457

  12. Adjusting the Chain Gear

    NASA Astrophysics Data System (ADS)

    Koloc, Z.; Korf, J.; Kavan, P.

    The adjustment (modification) deals with gear chains intermediating (transmitting) motion transfer between the sprocket wheels on parallel shafts. The purpose of the adjustments of chain gear is to remove the unwanted effects by using the chain guide on the links (sliding guide rail) ensuring a smooth fit of the chain rollers into the wheel tooth gap.

  13. EFFECTS OF ALTERNATE ANTIFOAM AGENTS, NOBLE METALS, MIXING SYSTEMS AND MASS TRANSFER ON GAS HOLDUP AND RELEASE FROM NONNEWTONIAN SLURRIES

    SciTech Connect

    Guerrero, H; Mark Fowley, M; Charles Crawford, C; Michael Restivo, M; Robert Leishear, R

    2007-12-24

    Gas holdup tests performed in a small-scale mechanically-agitated mixing system at the Savannah River National Laboratory (SRNL) were reported in 2006. The tests were for a simulant of waste from the Hanford Tank 241-AZ-101 and featured additions of DOW Corning Q2-3183A Antifoam agent. Results indicated that this antifoam agent (AFA) increased gas holdup in the waste simulant by about a factor of four and, counter intuitively, that the holdup increased as the simulant shear strength decreased (apparent viscosity decreased). These results raised questions about how the AFA might affect gas holdup in Hanford Waste Treatment and Immobilization Plant (WTP) vessels mixed by air sparging and pulse-jet mixers (PJMs). And whether the WTP air supply system being designed would have the capacity to handle a demand for increased airflow to operate the sparger-PJM mixing systems should the AFA increase retention of the radiochemically generated flammable gases in the waste by making the gas bubbles smaller and less mobile, or decrease the size of sparger bubbles making them mix less effectively for a given airflow rate. A new testing program was developed to assess the potential effects of adding the DOW Corning Q2-3183A AFA to WTP waste streams by first confirming the results of the work reported in 2006 by Stewart et al. and then determining if the AFA in fact causes such increased gas holdup in a prototypic sparger-PJM mixing system, or if the increased holdup is just a feature of the small-scale agitation system. Other elements of the new program include evaluating effects other variables could have on gas holdup in systems with AFA additions such as catalysis from trace noble metals in the waste, determining mass transfer coefficients for the AZ-101 waste simulant, and determining whether other AFA compositions such as Dow Corning 1520-US could also increase gas holdup in Hanford waste. This new testing program was split into two investigations, prototypic sparger

  14. Modulation of Symmetry-Breaking Intramolecular Charge-Transfer Dynamics Assisted by Pendant Side Chains in π-Linkers in Quadrupolar Diketopyrrolopyrrole Derivatives.

    PubMed

    Kim, Woojae; Sung, Jooyoung; Grzybowski, Marek; Gryko, Daniel T; Kim, Dongho

    2016-08-01

    The effect of the length of pendant side chains in centrosymmetric quadrupolar molecules on dynamics of their most perplexing photophysical phenomenon, i.e., symmetry-breaking intramolecular charge transfer, has been discovered. Unexpectedly, considerable influence of length of these pendant side chains in π-linkers arose as a structural factor enabling the control of the degree of fluorescence solvatochromism. The symmetry-breaking intramolecular charge-transfer dynamics has been described on quadrupolar diketopyrrolopyrrole derivatives possessing fluorene moieties as π-linkers and diarylamino groups as electron donors. On the basis of the evolution of transient fluorescence spectra obtained by a femtosecond broadband fluorescence up-conversion spectroscopy, it was found that the relative contribution of diffusive solvation and torsional relaxation in overall spectral relaxation can be modulated by the length of pendant side chain in π-linkers. Consequently, we demonstrated that this modulation plays a significant role in determining the photophysical properties of diketopyrrolopyrroles in a polar medium. PMID:27455383

  15. Building Pathways to Transfer: Community Colleges That Break the Chain of Failure for Students of Color. Policy Brief

    ERIC Educational Resources Information Center

    Civil Rights Project / Proyecto Derechos Civiles, 2012

    2012-01-01

    This study followed all freshman community college students in California who had demonstrated the intent to transfer from 1996, 1997, and 1998. Outcomes were assessed for each of the three entering cohorts after six years (2002-2004) and students were linked with their high schools of origin and the 4-year colleges to which they transferred. The…

  16. Ultrafast charge-transfer reactions of indoline dyes with anchoring alkyl chains of varying length in mesoporous ZnO solar cells.

    PubMed

    Rohwer, Egmont; Minda, Iulia; Tauscher, Gabriele; Richter, Christoph; Miura, Hidetoshi; Schlettwein, Derck; Schwoerer, Heinrich

    2015-04-01

    Dye-sensitized solar cells based on a mesoporous ZnO substrate were sensitized with the indoline derivatives DN91, DN216 and DN285. The chromophore is the same for each of these dyes. They differ from each other in the length of an alkyl chain, which provides a second anchor to the ZnO surface and prolongs cell lifetime. Ultrafast transient absorption measurements reveal a correlation between the length of the alkyl chain and the fastest electron-injection process. The depopulation of the excited state and the associated emergence of the oxidized molecules are dominant spectral features in the transient absorption of the dyes with shorter alkyl chains. A slower picosecond-scale decay proceeds at constant rate for all three derivatives and is assigned to electron transfer into the trap states of ZnO. All assignments are in good agreement with a higher quantum efficiency of charge injection leading to higher short-circuit currents J(sc) for dyes with shorter alkyl chains. PMID:25652263

  17. Anti-CD20 single chain variable antibody fragment–apolipoprotein A-I chimera containing nanodisks promote targeted bioactive agent delivery to CD20-positive lymphomas

    PubMed Central

    Crosby, Natasha M.; Ghosh, Mistuni; Su, Betty; Beckstead, Jennifer A.; Kamei, Ayako; Simonsen, Jens B.; Luo, Bing; Gordon, Leo I.; Forte, Trudy M.; Ryan, Robert O.

    2015-01-01

    A fusion protein comprising an α-CD20 single chain variable fragment (scFv) antibody, a spacer peptide, and human apolipoprotein (apo) A-I was constructed and expressed in Escherichia coli. The lipid interaction properties intrinsic to apoA-I as well as the antigen recognition properties of the scFv were retained by the chimera. scFv•apoA-I was formulated into nanoscale reconstituted high-density lipoprotein particles (termed nanodisks; ND) and incubated with cultured cells. α-CD20 scFv•apoA-I ND bound to CD20-positive non-Hodgkins lymphoma (NHL) cells (Ramos and Granta) but not to CD20-negative T lymphocytes (i.e., Jurkat). Binding to NHL cells was partially inhibited by pre-incubation with rituximab, a monoclonal antibody directed against CD20. Confocal fluorescence microscopy analysis of Granta cells following incubation with α-CD20 scFv•apoA-I ND formulated with the intrinsically fluorescent hydrophobic polyphenol, curcumin, revealed α-CD20 scFv•apoA-I localizes to the cell surface, while curcumin off-loads and gains entry to the cell. Compared to control incubations, viability of cultured NHL cells was decreased upon incubation with α-CD20 scFv•apoA-I ND harboring curcumin. Thus, formulation of curcumin ND with α-CD20 scFv•apoA-I as the scaffold component confers cell targeting and enhanced bioactive agent delivery, providing a strategy to minimize toxicity associated with chemotherapeutic agents. PMID:25994015

  18. Anti-CD20 single chain variable antibody fragment-apolipoprotein A-I chimera containing nanodisks promote targeted bioactive agent delivery to CD20-positive lymphomas.

    PubMed

    Crosby, Natasha M; Ghosh, Mistuni; Su, Betty; Beckstead, Jennifer A; Kamei, Ayako; Simonsen, Jens B; Luo, Bing; Gordon, Leo I; Forte, Trudy M; Ryan, Robert O

    2015-08-01

    A fusion protein comprising an α-CD20 single chain variable fragment (scFv) antibody, a spacer peptide, and human apolipoprotein (apo) A-I was constructed and expressed in Escherichia coli. The lipid interaction properties intrinsic to apoA-I as well as the antigen recognition properties of the scFv were retained by the chimera. scFv•apoA-I was formulated into nanoscale reconstituted high-density lipoprotein particles (termed nanodisks; ND) and incubated with cultured cells. α-CD20 scFv•apoA-I ND bound to CD20-positive non-Hodgkins lymphoma (NHL) cells (Ramos and Granta) but not to CD20-negative T lymphocytes (i.e., Jurkat). Binding to NHL cells was partially inhibited by pre-incubation with rituximab, a monoclonal antibody directed against CD20. Confocal fluorescence microscopy analysis of Granta cells following incubation with α-CD20 scFv•apoA-I ND formulated with the intrinsically fluorescent hydrophobic polyphenol, curcumin, revealed α-CD20 scFv•apoA-I localizes to the cell surface, while curcumin off-loads and gains entry to the cell. Compared to control incubations, viability of cultured NHL cells was decreased upon incubation with α-CD20 scFv•apoA-I ND harboring curcumin. Thus, formulation of curcumin ND with α-CD20 scFv•apoA-I as the scaffold component confers cell targeting and enhanced bioactive agent delivery, providing a strategy to minimize toxicity associated with chemotherapeutic agents. PMID:25994015

  19. Slow and fast singlet energy transfers in BODIPY-gallium(III)corrole dyads linked by flexible chains.

    PubMed

    Brizet, Bertrand; Desbois, Nicolas; Bonnot, Antoine; Langlois, Adam; Dubois, Adrien; Barbe, Jean-Michel; Gros, Claude P; Goze, Christine; Denat, Franck; Harvey, Pierre D

    2014-04-01

    Red (no styryl), green (monostyryl), and blue (distyryl) BODIPY-gallium(III) (BODIPY = boron-dipyrromethene) corrole dyads have been prepared in high yields using click chemistry, and their photophysical properties are reported. An original and efficient control of the direction of the singlet energy transfers is reported, going either from BODIPY to the gallium-corrole units or from gallium-corroles to BODIPY, depending upon the nature of the substitution on BODIPY. In one case (green), both directions are possible. The mechanism for the energy transfers is interpreted by means of through-space Förster resonance energy transfer (FRET). PMID:24661249

  20. Transfer of radiocaesium from contaminated bottom sediments to marine organisms through benthic food chains in post-Fukushima and post-Chernobyl periods

    NASA Astrophysics Data System (ADS)

    Bezhenar, Roman; Jung, Kyung Tae; Maderich, Vladimir; Willemsen, Stefan; de With, Govert; Qiao, Fangli

    2016-05-01

    After the earthquake and tsunami on 11 March 2011 damaged the Fukushima Dai-ichi Nuclear Power Plant (FDNPP), an accidental release of a large amount of radioactive isotopes into both the air and the ocean occurred. Measurements provided by the Japanese agencies over the past 5 years show that elevated concentrations of 137Cs still remain in sediments, benthic organisms, and demersal fishes in the coastal zone around the FDNPP. These observations indicate that there are 137Cs transfer pathways from bottom sediments to the marine organisms. To describe the transfer quantitatively, the dynamic food chain biological uptake model of radionuclides (BURN) has been extended to include benthic marine organisms. The extended model takes into account both pelagic and benthic marine organisms grouped into several classes based on their trophic level and type of species: phytoplankton, zooplankton, and fishes (two types: piscivorous and non-piscivorous) for the pelagic food chain; deposit-feeding invertebrates, demersal fishes fed by benthic invertebrates, and bottom omnivorous predators for the benthic food chain; crustaceans, mollusks, and coastal predators feeding on both pelagic and benthic organisms. Bottom invertebrates ingest organic parts of bottom sediments with adsorbed radionuclides which then migrate up through the food chain. All organisms take radionuclides directly from water as well as food. The model was implemented into the compartment model POSEIDON-R and applied to the north-western Pacific for the period of 1945-2010, and then for the period of 2011-2020 to assess the radiological consequences of 137Cs released due to the FDNPP accident. The model simulations for activity concentrations of 137Cs in both pelagic and benthic organisms in the coastal area around the FDNPP agree well with measurements for the period of 2011-2015. The decrease constant in the fitted exponential function of simulated concentration for the deposit-feeding invertebrates (0.45 yr-1

  1. Polymerase chain reaction detection of Leishmania DNA in skin biopsy samples in Sri Lanka where the causative agent of cutaneous leishmaniasis is Leishmania donovani.

    PubMed

    Ranasinghe, Shalindra; Wickremasinghe, Renu; Hulangamuwa, Sanjeeva; Sirimanna, Ganga; Opathella, Nandimithra; Maingon, Rhaiza D C; Chandrasekharan, Vishvanath

    2015-12-01

    Leishmania donovani is the known causative agent of both cutaneous (CL) and visceral leishmaniasis in Sri Lanka. CL is considered to be under-reported partly due to relatively poor sensitivity and specificity of microscopic diagnosis. We compared robustness of three previously described polymerase chain reaction (PCR) based methods to detect Leishmania DNA in 38 punch biopsy samples from patients presented with suspected lesions in 2010. Both, Leishmania genus-specific JW11/JW12 KDNA and LITSR/L5.8S internal transcribed spacer (ITS)1 PCR assays detected 92% (35/38) of the samples whereas a KDNA assay specific forL. donovani (LdF/LdR) detected only 71% (27/38) of samples. All positive samples showed a L. donovani banding pattern upon HaeIII ITS1 PCR-restriction fragment length polymorphism analysis. PCR assay specificity was evaluated in samples containing Mycobacterium tuberculosis, Mycobacterium leprae, and human DNA, and there was no cross-amplification in JW11/JW12 and LITSR/L5.8S PCR assays. The LdF/LdR PCR assay did not amplify M. leprae or human DNA although 500 bp and 700 bp bands were observed in M. tuberculosis samples. In conclusion, it was successfully shown in this study that it is possible to diagnose Sri Lankan CL with high accuracy, to genus and species identification, using Leishmania DNA PCR assays. PMID:26676321

  2. Polymerase chain reaction detection of Leishmania DNA in skin biopsy samples in Sri Lanka where the causative agent of cutaneous leishmaniasis is Leishmania donovani

    PubMed Central

    Ranasinghe, Shalindra; Wickremasinghe, Renu; Hulangamuwa, Sanjeeva; Sirimanna, Ganga; Opathella, Nandimithra; Maingon, Rhaiza DC; Chandrasekharan, Vishvanath

    2015-01-01

    Leishmania donovani is the known causative agent of both cutaneous (CL) and visceral leishmaniasis in Sri Lanka. CL is considered to be under-reported partly due to relatively poor sensitivity and specificity of microscopic diagnosis. We compared robustness of three previously described polymerase chain reaction (PCR) based methods to detectLeishmania DNA in 38 punch biopsy samples from patients presented with suspected lesions in 2010. Both, Leishmaniagenus-specific JW11/JW12 KDNA and LITSR/L5.8S internal transcribed spacer (ITS)1 PCR assays detected 92% (35/38) of the samples whereas a KDNA assay specific forL. donovani (LdF/LdR) detected only 71% (27/38) of samples. All positive samples showed a L. donovani banding pattern upon HaeIII ITS1 PCR-restriction fragment length polymorphism analysis. PCR assay specificity was evaluated in samples containing Mycobacterium tuberculosis, Mycobacterium leprae, and human DNA, and there was no cross-amplification in JW11/JW12 and LITSR/L5.8S PCR assays. The LdF/LdR PCR assay did not amplify M. leprae or human DNA although 500 bp and 700 bp bands were observed in M. tuberculosis samples. In conclusion, it was successfully shown in this study that it is possible to diagnose Sri Lankan CL with high accuracy, to genus and species identification, using Leishmania DNA PCR assays. PMID:26676321

  3. Insight into the stereospecificity of short-chain thermus thermophilus alcohol dehydrogenase showing pro-S hydride transfer and prelog enantioselectivity.

    PubMed

    Pennacchio, Angela; Giordano, Assunta; Esposito, Luciana; Langella, Emma; Rossi, Mosè; Raia, Carlo A

    2010-04-01

    The stereochemistry of the hydride transfer in reactions catalyzed by NAD(H)-dependent alcohol dehydrogenase from Thermus thermophilus HB27 was determined by means of (1)H-NMR spectroscopy. The enzyme transfers the pro-S hydrogen of [4R-(2)H]NADH and exhibits Prelog specificity. Enzyme-substrate docking calculations provided structural details about the enantioselectivity of this thermophilic enzyme. These results give additional insights into the diverse active site architectures of the largely versatile short-chain dehydrogenase superfamily enzymes. A feasible protocol for the synthesis of [4R-(2)H]NADH with high yield was also set up by enzymatic oxidation of 2-propanol-d(8) catalyzed by Bacillus stearothermophilus alcohol dehydrogenase. PMID:19807673

  4. Assessing the involvement of migratory dendritic cells in the transfer of the scrapie agent from the immune to peripheral nervous systems.

    PubMed

    Raymond, Claudine R; Mabbott, Neil A

    2007-07-01

    Many transmissible spongiform encephalopathy (TSE) agents accumulate upon follicular dendritic cells (FDCs) in lymphoid tissues before spreading to the brain. How TSE agents spread from FDCs to the nervous system is not known as there is no physical FDC-nerve synapse. As FDCs form immobile networks we investigated whether other mobile cells might transfer TSE agents between FDCs and peripheral nerves. We show that scrapie-infected mononuclear cells, B cells and migratory dendritic cells (DCs) were unable to efficiently transmit disease to the peripheral nervous systems (PNSs) of FDC-deficient TNFR1(-/-) mice. These findings differed significantly from a similar study which suggested that scrapie-infected DCs could efficiently transmit disease directly to FDC-deficient RAG1(-/-) mice. Comparison of the innervation in spleens from TNFR1(-/-) mice and RAG1(-/-) mice indicated that the density of sympathetic nerves was much higher in RAG1(-/-) mice. These data imply that DCs could efficiently transmit disease directly to RAG1(-/-) mice because their spleens were highly innervated, but not to TNFR1(-/-) mice because their spleens were less densely innervated. As the density of the innervation in the spleens of wild-type mice also appeared to be much lower than that of RAG1(-/-) mice our data suggest that DCs are unlikely to play a key role in the transfer of TSE agents from FDCs to the PNS of wild-type mice. PMID:17561271

  5. Toxicity and transfer of polyvinylpyrrolidone-coated silver nanowires in an aquatic food chain consisting of algae, water fleas, and zebrafish.

    PubMed

    Chae, Yooeun; An, Youn-Joo

    2016-04-01

    Nanomaterials of various shapes and dimensions are widely used in the medical, chemical, and electronic industries. Multiple studies have reported the ecotoxicological effects of nanaoparticles when released in aquatic and terrestrial ecosystems; however, information on the toxicity of silver nanowires (AgNWs) to freshwater organisms and their transfer through the food webs is limited. In the present study, we aimed to evaluate the toxicity of 10- and 20-μm-long AgNWs to the alga Chlamydomonas reinhardtii, the water flea Daphnia magna, and the zebrafish and study their movement through this three-species food chain using a variety of qualitative and quantitative methods as well as optical techniques. We found that AgNWs directly inhibited the growth of algae and destroyed the digestive organs of water fleas. The results showed that longer AgNWs (20μm) were more toxic than shorter ones (10μm) to both algae and water fleas, but shorter AgNWs were accumulated more than longer ones in the body of the fish. Overall, this study suggests that AgNWs are transferred through food chains, and that they affect organisms at higher trophic levels, potentially including humans. Therefore, further studies that take into account environmental factors, food web complexity, and differences between nanomaterials are required to gain better understanding of the impact of nanomaterials on natural communities and human health. PMID:26854872

  6. Long-time dynamics of quantum chains: Transfer-matrix renormalization group and entanglement of the maximal eigenvector

    NASA Astrophysics Data System (ADS)

    Huang, Yu-Kun; Chen, Pochung; Kao, Ying-Jer; Xiang, Tao

    2014-05-01

    By using a different quantum-to-classical mapping from the Trotter-Suzuki decomposition, we identify the entanglement structure of the maximal eigenvectors for the associated quantum transfer matrix. This observation provides a deeper insight into the problem of linear growth of the entanglement entropy in time evolution using conventional methods. Based on this observation, we propose a general method for arbitrary temperatures using the biorthonormal transfer-matrix renormalization group. Our method exhibits a competitive accuracy with a much cheaper computational cost in comparison with two recently proposed methods for long-time dynamics based on a folding algorithm [Phys. Rev. Lett. 102, 240603 (2009), 10.1103/PhysRevLett.102.240603] and a modified time-dependent density-matrix renormalization group [Phys. Rev. Lett. 108, 227206 (2012), 10.1103/PhysRevLett.108.227206].

  7. Trophic transfer and accumulation of TiO2 nanoparticles from clamworm (Perinereis aibuhitensis) to juvenile turbot (Scophthalmus maximus) along a marine benthic food chain.

    PubMed

    Wang, Zhenyu; Yin, Liyun; Zhao, Jian; Xing, Baoshan

    2016-05-15

    In the present work, we investigated the potential benthic trophic transfer of TiO2 nanoparticles (NPs) from clamworm (Perinereis aibuhitensis) to juvenile turbot (Scophthalmus maximus) and their related distribution and toxicity. TiO2 NPs (at 10, 50 and 100 mg/L) could be taken up by clamworms, and mainly accumulated in the lower-digestive tract. TiO2 NPs were able to transfer from clamworms to juvenile turbots. The accumulation of TiO2 NPs in juvenile turbots increased with increasing Ti contents in clamworms during the dietary exposure, however, no biomagnification (BMFs, 0.30-0.33) of TiO2 NPs was observed. For both dietary and waterborne exposure, accumulation of TiO2 NPs was higher in the gill, intestine and stomach of juvenile turbot, following by skin, liver, and muscle. During dietary exposure at Day 20, the growth of turbots was reduced, and abnormal symptoms of liver and spleen were detected. Moreover, both dietary (50 and 100 mg/L TiO2 NPs-treated clamworms) and waterborne (100 mg/L TiO2 NPs) exposures led to significantly lower protein and higher lipid contents, suggesting the nutrition quality reduction of turbots. The findings from this work highlighted the trophic transfer of TiO2 NPs in marine benthic food chain, leading to the potential negative impact on marine aquaculture and food quality. PMID:27010785

  8. Facile Synthesis of Thiol-terminated Poly(styrene-ran-vinyl phenol) (PSVPh) Copolymers via Reversible Addition-Fragmentation Chain Transfer (RAFT) Polymerization and Their Use in the Synthesis of Gold Nanoparticles with Controllable Hydrophilicity

    SciTech Connect

    Lee, Chang-Uk; Roy, Debashish; Dadmun, Mark D

    2010-01-01

    A facile approach to prepare thiol-terminated poly(styrene-ran-vinyl phenol) (PSVPh) copolymers and PSVPh-coated gold nanoparticles is reported with the goal of creating stabilizing ligands for nanoparticles with controlled hydrophilicity. Dithioester-terminated poly(styrene-ran-acetoxystyrene) copolymers were synthesized via RAFT polymerization using cumyl dithiobenzoate as a chain transfer agent. These copolymers were converted to thiol-terminated PSVPh copolymers by a one step hydrazinolysis reaction using hydrazine hydrate to simultaneously convert dithioester-terminal and acetoxypendant groups to thiol-terminal and hydroxyl-pendant groups, respectively. Spectroscopic observations including NMR and IR confirm end- and pendant-group conversion. PSVPh-coated gold nanoparticles were synthesized in the presence of a mixture of thiol-terminated PSVPh and PSVPh copolymers containing disulfides as stabilizing ligands in a water/toluene, two-phase system. The size and size distribution of core gold nanoparticles were determined by TEM and image analysis. The hydrodynamic radius of PSVPh-coated gold nanoparticles was also determined by dynamic light scattering experiment, which confirms the particle analysis by TEM. This procedure provides a facile technique to control the polarity and hydrophilicity of metal nanoparticle surfaces and could prove critical in advancing the control of nanoparticle placement in biological and hierarchically ordered systems, such as diblock copolymers.

  9. Real-time trace detection and identification of chemical warfare agent simulants using recent advances in proton transfer reaction time-of-flight mass spectrometry.

    PubMed

    Petersson, Fredrik; Sulzer, Philipp; Mayhew, Chris A; Watts, Peter; Jordan, Alfons; Märk, Lukas; Märk, Tilmann D

    2009-12-01

    This work demonstrates for the first time the potential of using recent developments in proton transfer reaction mass spectrometry for the rapid detection and identification of chemical warfare agents (CWAs) in real-time. A high-resolution (m/Deltam up to 8000) and high-sensitivity (approximately 50 cps/ppbv) proton transfer reaction time-of-flight mass spectrometer (PTR-TOF 8000 from Ionicon Analytik GmBH) has been successfully used to detect a number of CWA simulants at room temperature; namely dimethyl methylphosphonate, diethyl methylphosphonate, diisopropyl methylphosphonate, dipropylene glycol monomethyl ether and 2-chloroethyl ethyl sulfide. Importantly, we demonstrate in this paper the potential to identify CWAs with a high level of confidence in complex chemical environments, where multiple threat agents and interferents could also be present in trace amounts, thereby reducing the risk of false positives. Instantaneous detection and identification of trace quantities of chemical threats using proton transfer reaction mass spectrometry could form the basis for a timely warning system capability with greater precision and accuracy than is currently provided by existing analytical technologies. PMID:19902419

  10. Photoinduced electron transfer double fragmentation. An oxygen-mediated radical chain process in the cofragmentation of aminopinacol donors with organic halides

    SciTech Connect

    Chen, L.; Farahat, M.S.; Gan, H.; Whitten, D.G.; Farid, S. |

    1995-06-14

    We reprot an investigation in which excited states of amino pinacols 1-3 are reacted with the halides CCl{sub 4}, benzyl bromide, and p-cyanobenzyl bromide. Interesting results from this study include the finding that low-to-moderate quantum efficiencies for reaction are observed when the reactions are carried out under degassed conditions, indicating that the halide radical anions must survive long enough within the initial ion pair formed in the quenching step to undergo considerable return electron transfer. More strikingly we find that for certain pinacol-halide combinations reaction in aerared solutions leads to much higher efficiencies, which can be attributed to a chain reaction involving oxygen capture of a primary radical product. 25 refs., 1 fig., 1 tab.

  11. Bioaccumulation and food-chain transfer of polycyclic aromatic hydrocarbons and heavy metals: A laboratory and field investigation. Final report, 15 Oct 91-14 Oct 92

    SciTech Connect

    Clements, W.H.

    1992-10-14

    The extent to which heavy metals and Polycyclic aromatic hydrocarbons (PAH) may be transferred up the food chain from sediments to benthic invertebrates and then on to fish species was examined using both laboratory and field techniques. PAHs were shown to bioaccumulate in a chironomid invertebrate (chironomus riparius) to relatively high levels depending on the specific compound. Accumulation in a fish specie (Lepomis macrochirus) that was fed contaminated chironomids was found to be generally low. Mobilization of PAHs from sediments into water was affected by benthic organisms enhancing the bioavailability of these contaminants to other organisms. In field studies, certain benthic invertebrates and abiotic sediment components were also shown to accumulate heavy metals. This metal accumulation persisted even when metal concentrations in the water were diminishing.

  12. Anomalous charge and negative-charge-transfer insulating state in cuprate chain compound KCuO2

    NASA Astrophysics Data System (ADS)

    Choudhury, D.; Rivero, P.; Meyers, D.; Liu, X.; Cao, Y.; Middey, S.; Whitaker, M. J.; Barraza-Lopez, S.; Freeland, J. W.; Greenblatt, M.; Chakhalian, J.

    2015-11-01

    Using a combination of x-ray absorption spectroscopy (XAS) experiments and first-principles calculations, we demonstrate that insulating KCuO2 contains Cu in an unusually high formal 3+ valence state, and the ligand-to-metal (O-to-Cu) charge-transfer energy is intriguingly negative (Δ ˜-1.5 eV) and has a dominant (˜60 % ) ligand-hole character in the ground state akin to the high Tc cuprate Zhang-Rice state. Unlike most other formal Cu3 + compounds, the Cu 2 p XAS spectra of KCuO2 exhibit pronounced 3 d8 (Cu3 +) multiplet structures, which account for ˜40 % of its ground state wave function. Ab initio calculations elucidate the origin of the band gap in KCuO2 as arising primarily from strong intracluster Cu 3 d -O 2 p hybridizations (tpd); the value of the band gap decreases with a reduced value of tpd. Further, unlike conventional negative-charge-transfer insulators, the band gap in KCuO2 persists even for vanishing values of Coulomb repulsion U , underscoring the importance of single-particle band-structure effects connected to the one-dimensional nature of the compound.

  13. [The transfer of 90Sr and of 137Cs radionuclides in the chain of soil-fodder-animal products in the area contaminated as a consequence of the Chernobyl AES accident].

    PubMed

    Spirin, E V; Aleksakhin, R M; Kalmykov, M V; Ageets, V Iu; Averin, V S; Lazarev, N M; Cavellin, G D; Biesold, H

    2006-01-01

    The database on 137Cs and or 90Sr transfer factors in the soil-fodder-animal products chain compiled in the framework of the project "Radioecological Consequences of the Chernobyl Accident" under the French-German Initiative was analyzed. The 137Cs transfer factors were determined into 10 fodder types for farm animals. The 137Cs and 90Sr transfer from daily diet to milk is practically independent from milk yield and season and is about 0.83% and 0.16%. 137Cs transfer factor into beef (adult animals) is about to 2.4% from the daily uptake with fodder per 1 kg meat. PMID:16579548

  14. Synchrotron verification of TiO2 accumulation in cucumber fruit: a possible pathway of TiO2 nanoparticle transfer from soil into the food chain.

    PubMed

    Servin, Alia D; Morales, Maria Isabel; Castillo-Michel, Hiram; Hernandez-Viezcas, Jose Angel; Munoz, Berenice; Zhao, Lijuan; Nunez, Jose E; Peralta-Videa, Jose R; Gardea-Torresdey, Jorge L

    2013-10-15

    The transfer of nanoparticles (NPs) into the food chain through edible plants is of great concern. Cucumis sativus L. is a freshly consumed garden vegetable that could be in contact with NPs through biosolids and direct agrichemical application. In this research, cucumber plants were cultivated for 150 days in sandy loam soil treated with 0 to 750 mg TiO2 NPs kg(-1). Fruits were analyzed using synchrotron μ-XRF and μ-XANES, ICP-OES, and biochemical assays. Results showed that catalase in leaves increased (U mg(-1) protein) from 58.8 in control to 78.8 in 750 mg kg(-1) treatment; while ascorbate peroxidase decreased from 21.9 to 14.1 in 500 mg kg(-1) treatment. Moreover, total chlorophyll content in leaves increased in the 750 mg kg(-1) treatment. Compared to control, FTIR spectra of fruit from TiO2 NP treated plants showed significant differences (p ≤ 0.05) in band areas of amide, lignin, and carbohydrates, suggesting macromolecule modification of cucumber fruit. In addition, compared with control, plants treated with 500 mg kg(-1) had 35% more potassium and 34% more phosphorus. For the first time, μ-XRF and μ-XANES showed root-to-fruit translocation of TiO2 in cucumber without biotransformation. This suggests TiO2 could be introduced into the food chain with unknown consequences. PMID:24040965

  15. Risks associated with the transfer of toxic organo-metallic mercury from soils into the terrestrial feed chain.

    PubMed

    Henriques, Bruno; Rodrigues, S M; Coelho, C; Cruz, N; Duarte, A C; Römkens, P F A M; Pereira, E

    2013-09-01

    Although the transfer of organo-metallic mercury (OrgHg) in aquatic food webs has long been studied, it has only been recently recognized that there is also accumulation in terrestrial systems. There is still however little information about the exposure of grazing animals to OrgHg from soils and feed as well as on risks of exposure to animal and humans. In this study we collected 78 soil samples and 40 plant samples (Lolium perenne and Brassica juncea) from agricultural fields near a contaminated industrial area and evaluated the soil-to-plant transfer of Hg as well as subsequent trophic transfer. Inorganic Hg (IHg) concentrations ranged from 0.080 to 210mgkg(-1) d.w. in soils, from 0.010 to 84mgkg(-1) d.w. in roots and from 0.020 to 6.9mgkg(-1) d.w. in shoots. OrgHg concentrations in soils varied between 0.20 and 130μgkg(-1) d.w. representing on average 0.13% of the total Hg (THg). In root and shoot samples OrgHg comprised on average 0.58% (roots) and 0.66% (shoots) of THg. Average bioaccumulation factors (BAFs) for OrgHg in relation to soil concentrations were 3.3 (for roots) and 1.5 (for shoots). The daily intake (DI) of THg in 33 sampling sites exceeded the acceptable daily intake (ADI) of THg of both cows (ADI=1.4mgd(-1)) and sheep (ADI=0.28mgd(-1)), in view of food safety associated with THg in animal kidneys. Estimated DI of OrgHg for grazing animals were up to 220μgd(-1) (for cows) and up to 33μgd(-1) (for sheep). This study suggested that solely monitoring the levels of THg in soils and feed may not allow to adequately taking into account accumulation of OrgHg in feed crops and properly address risks associated with OrgHg exposure for animals and humans. Hence, the inclusion of limits for OrgHg in feed quality and food safety legislation is advised. PMID:23917441

  16. 76 FR 16707 - Rule 17Ad-17; Transfer Agents', Brokers', and Dealers' Obligation To Search for Lost...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-03-25

    ... Act Release No. 39176 (Oct. 1, 1997), 62 FR 52229 (Oct. 7, 1997) (adopting Rule 17Ad-17). \\14\\ See id... pursuant to the state's escheatment laws. \\16\\ See Exchange Act Release No. 37595 (Aug. 22, 1996), 61 FR... Search for Lost Securityholders; Paying Agents' Obligation To Search for Missing Securityholders...

  17. Effects of sewage sludge amendment on snail growth and trace metal transfer in the soil-plant-snail food chain.

    PubMed

    Bourioug, Mohamed; Gimbert, Frédéric; Alaoui-Sehmer, Laurence; Benbrahim, Mohammed; Badot, Pierre-Marie; Alaoui-Sossé, Badr; Aleya, Lotfi

    2015-11-01

    Cu, Zn, Pb, and Cd concentrations in a soil plant (Lactuca sativa) continuum were measured after sewage sludge amendment. The effects of sewage sludge on growth and trace metal bioaccumulation in snails (Cantareus aspersus) were investigated in a laboratory experiment specifically designed to identify contamination sources (e.g., soil and leaves). Application of sewage sludge increased trace metal concentrations in topsoil. However, except Zn, metal concentrations in lettuce leaves did not reflect those in soil. Lettuce leaves were the main source of Zn, Cu, and Cd in exposed snails. Bioaccumulation of Pb suggested its immediate transfer to snails via the soil. No apparent toxic effects of trace metal accumulation were observed in snails. Moreover, snail growth was significantly stimulated at high rates of sludge application. This hormesis effect may be due to the enhanced nutritional content of lettuce leaves exposed to sewage sludge. PMID:26165994

  18. Using a Commercial Ultrasound Contrast Agent for Viral-Mediated Gene Transfer In Vitro and In Vivo

    NASA Astrophysics Data System (ADS)

    Howard, Candace M.; Forsberg, Flemming; Liu, Ji-Bin; Merton, Daniel A.; Minimo, Corrado; Claudio, Pier P.

    2007-05-01

    This study evaluated the feasibility of site-specific gene delivery mediated by diagnostic ultrasound using genes encapsulated in commercially available ultrasound contrast agents in vitro and in vivo. Five different commercially available contrast agents were tested in vitro for their ability to enclose an adenoviral vector carrying GFP. Prostate cancer cells (DU 145) or non small cell lung cancer cells (H23) were plated in 80 culture wells and insonified at 207 or 535 kPa peak negative pressure for 1 min after administration of 0.1 ml of bubbles reconstituted with the viral vector. Experiments were repeated with the delivery vehicle incubated with complement to inactivate unenclosed Adeno-GFP and with controls. After 24 hours transduction efficiency was demonstrated by fluorescent microscopy. In vivo 15 nude mice with 21 melanoma tumors (DB-1) implanted received 0.1 ml injections of contrast. Mice were split into 3 control and 4 active groups and ultrasound was performed for 4 min at 4 MHz using an Aplio scanner (Toshiba America Medical Systems, Tustin, CA). Tumors, heart, lungs and liver were harvested 48 hours later. Specimens underwent regular and fluorescent microscopy and were stained using an antibody against GFP. In vitro all contrast agents produced more fluorescence at 207 kPa than at 535 kPa. However, only Imagent (IMCOR Pharmaceuticals, San Diego, CA) was able to induce marked gene transduction with the inactivating agent. In vivo systemic delivery of Adeno-GFP carrying microbubbles following pre-treatment with the inactivating agent resulted in specific transduction of the tumor cells only with no uptake in heart, lungs or liver (unlike the controls). In conclusion, specific viral gene transduction has been obtained in vitro and in vivo through the use of ultrasound and Imagent microbubbles as delivery vehicles.

  19. A Gene Transfer Agent and a Dynamic Repertoire of Secretion Systems Hold the Keys to the Explosive Radiation of the Emerging Pathogen Bartonella

    PubMed Central

    Guy, Lionel; Nystedt, Björn; Toft, Christina; Zaremba-Niedzwiedzka, Katarzyna; Berglund, Eva C.; Granberg, Fredrik; Näslund, Kristina; Eriksson, Ann-Sofie; Andersson, Siv G. E.

    2013-01-01

    Gene transfer agents (GTAs) randomly transfer short fragments of a bacterial genome. A novel putative GTA was recently discovered in the mouse-infecting bacterium Bartonella grahamii. Although GTAs are widespread in phylogenetically diverse bacteria, their role in evolution is largely unknown. Here, we present a comparative analysis of 16 Bartonella genomes ranging from 1.4 to 2.6 Mb in size, including six novel genomes from Bartonella isolated from a cow, two moose, two dogs, and a kangaroo. A phylogenetic tree inferred from 428 orthologous core genes indicates that the deadly human pathogen B. bacilliformis is related to the ruminant-adapted clade, rather than being the earliest diverging species in the genus as previously thought. A gene flux analysis identified 12 genes for a GTA and a phage-derived origin of replication as the most conserved innovations. These are located in a region of a few hundred kb that also contains 8 insertions of gene clusters for type III, IV, and V secretion systems, and genes for putatively secreted molecules such as cholera-like toxins. The phylogenies indicate a recent transfer of seven genes in the virB gene cluster for a type IV secretion system from a cat-adapted B. henselae to a dog-adapted B. vinsonii strain. We show that the B. henselae GTA is functional and can transfer genes in vitro. We suggest that the maintenance of the GTA is driven by selection to increase the likelihood of horizontal gene transfer and argue that this process is beneficial at the population level, by facilitating adaptive evolution of the host-adaptation systems and thereby expansion of the host range size. The process counters gene loss and forces all cells to contribute to the production of the GTA and the secreted molecules. The results advance our understanding of the role that GTAs play for the evolution of bacterial genomes. PMID:23555299

  20. One for All or All for One: Heterogeneous Expression and Host Cell Lysis Are Key to Gene Transfer Agent Activity in Rhodobacter capsulatus

    PubMed Central

    Fogg, Paul C. M.; Westbye, Alexander B.; Beatty, J. Thomas

    2012-01-01

    The gene transfer agent (RcGTA) of Rhodobacter capsulatus is the model for a family of novel bacteriophage-related genetic elements that carry out lateral transfer of essentially random host DNA. Genuine and putative gene transfer agents have been discovered in diverse genera and are becoming recognized as potentially an important source of genetic exchange and microbial evolution in the oceans. Despite being discovered over 30 years ago, little is known about many essential aspects of RcGTA biology. Here, we validate the use of direct fluorescence reporter constructs, which express the red fluorescent protein mCherry in R. capsulatus. A construct containing the RcGTA promoter fused to mCherry was used to examine the single-cell expression profiles of wild type and RcGTA overproducer R. capsulatus populations, under different growth conditions and growth phases. The majority of RcGTA production clearly arises from a small, distinct sub-set of the population in the wild type strain and a larger sub-set in the overproducer. The most likely RcGTA release mechanism concomitant with this expression pattern is host cell lysis and we present direct evidence for the release of an intracellular enzyme accompanying RcGTA release. RcGTA ORF s is annotated as a ‘cell wall peptidase’ but we rule out a role in host lysis and propose an alternative function as a key contributor to RcGTA invasion of a target cell during infection. PMID:22916305

  1. Food-chain transfer of cadmium and zinc from contaminated Urtica dioica to Helix aspersa and Lumbricus terrestris.

    PubMed

    Sinnett, Danielle E; Hodson, Mark E; Hutchings, Tony R

    2009-08-01

    The present study examines the potential of Urtica dioica as an ecologically relevant species for use in ecotoxicological testing. It is prevalent in degraded ecosystems and is a food source for invertebrates. Urtica dioica grown in hydroponic solutions containing from less than 0.003 to 5.7 mg Cd/L or from 0.02 to 41.9 mg Zn/L accumulated metals resulting in leaf tissue concentrations in the range of 0.10 to 24.9 mg Cd/kg or 22.5 to 2,772.0 mg Zn/kg. No toxicological effects were apparent except at the highest concentrations tested, suggesting that this species may be an important pathway for transfer of metals to primary plant consumers. Helix aspersa and Lumbricus terrestris were fed the Cd- and Zn-rich leaves of U. dioica for six and four weeks, respectively. Cadmium and Zn body load increased with increasing metal concentration in the leaves (p < 0.001). Ratios of invertebrate metal concentration to leaf metal concentration were in the range of 1:0.03 to 1:1.4 for Cd and 1:0.2 to 1:2.8 for Zn in H. aspersa and 1:0.002 to 1:3.9 for Cd and 1:0.2 to 1:8.8 for Zn in L. terrestris. Helix aspersa Cd and Zn tissue concentrations (15.5 and 1,220.2 mg/kg, respectively) were approximately threefold those in L. terrestris when both species were fed nettle leaves with concentrations of approximately 23 mg Cd/kg and 3,400 mg Zn/kg. Models demonstrate that L. terrestris Cd tissue concentrations (r2 = 0.74, p < 0.001) and H. aspersa Zn tissue concentrations (r(2) = 0.69, p < 0.001) can be estimated from concentrations of Cd and Zn within the leaves of U. dioica and suggest that reasonably reproducible results can be obtained using these species for ecotoxicological testing. PMID:19292567

  2. Green Preparation of Epoxy/Graphene Oxide Nanocomposites Using a Glycidylamine Epoxy Resin as the Surface Modifier and Phase Transfer Agent of Graphene Oxide.

    PubMed

    Tang, Xinlei; Zhou, Yang; Peng, Mao

    2016-01-27

    In studies of epoxy/graphene oxide (GO) nanocomposites, organic solvents are commonly used to disperse GO, and vigorous mechanical processes and complicated modification of GO are usually required, increasing the cost and hindering the development and application of epoxy nanocomposites. Here, we report a green, facile, and efficient method of preparing epoxy/GO nanocomposites. When triglycidyl para-aminophenol (TGPAP), a commercially available glycidyl amine epoxy resin with one tertiary amine group per molecule, is used as both the surface modifier and phase transfer agent of GO, GO can be directly and rapidly transferred from water to diglycidyl ether of bisphenol A and other types of epoxy resins by manual stirring under ambient conditions, whereas GO cannot be transferred to these epoxy resins in the absence of TGPAP. The interaction between TGPAP and GO and the effect of the TGPAP content on the dispersion of GO in the epoxy matrix were investigated systematically. Superior dispersion and exfoliation of GO nanosheets and remarkably improved mechanical properties, including tensile and flexural properties, toughness, storage modulus, and microhardness, of the epoxy/GO nanocomposites with a suitable amount of TGPAP were demonstrated. This method is organic-solvent-free and technically feasible for large-scale preparation of high-performance nanocomposites; it opens up new opportunities for exploiting the unique properties of graphene or even other nanofillers for a wide range of applications. PMID:26720708

  3. Cytomegalovirus survival and transferability and the effectiveness of common hand-washing agents against cytomegalovirus on live human hands.

    PubMed

    Stowell, Jennifer D; Forlin-Passoni, Daniela; Radford, Kay; Bate, Sheri L; Dollard, Sheila C; Bialek, Stephanie R; Cannon, Michael J; Schmid, D Scott

    2014-01-01

    Congenital cytomegalovirus (CMV) transmission can occur when women acquire CMV while pregnant. Infection control guidelines may reduce risk for transmission. We studied the duration of CMV survival after application of bacteria to the hands and after transfer from the hands to surfaces and the effectiveness of cleansing with water, regular and antibacterial soaps, sanitizer, and diaper wipes. Experiments used CMV AD169 in saliva at initial titers of 1 × 10(5) infectious particles/ml. Samples from hands or surfaces (points between 0 and 15 min) were placed in culture and observed for at least 2 weeks. Samples were also tested using CMV real-time PCR. After application of bacteria to the hands, viable CMV was recovered from 17/20 swabs at 0 min, 18/20 swabs at 1 min, 5/20 swabs at 5 min, and 4/20 swabs at 15 min. After transfer, duration of survival was at least 15 min on plastic (1/2 swabs), 5 min on crackers and glass (3/4 swabs), and 1 min or less on metal and cloth (3/4 swabs); no viable virus was collected from wood, rubber, or hands. After cleansing, no viable virus was recovered using water (0/22), plain soap (0/20), antibacterial soap (0/20), or sanitizer (0/22). Viable CMV was recovered from 4/20 hands 10 min after diaper wipe cleansing. CMV remains viable on hands for sufficient times to allow transmission. CMV may be transferred to surfaces with reduced viability. Hand-cleansing methods were effective at eliminating viable CMV from hands. PMID:24185855

  4. Homologues of Genetic Transformation DNA Import Genes Are Required for Rhodobacter capsulatus Gene Transfer Agent Recipient Capability Regulated by the Response Regulator CtrA

    PubMed Central

    Brimacombe, Cedric A.; Ding, Hao; Johnson, Jeanette A.

    2015-01-01

    ABSTRACT Gene transfer agents (GTAs) morphologically resemble small, double-stranded DNA (dsDNA) bacteriophages; however, their only known role is to package and transfer random pieces of the producing cell genome to recipient cells. The best understood GTA is that of Rhodobacter capsulatus, termed RcGTA. We discovered that homologues of three genes involved in natural transformation in other bacteria, comEC, comF, and comM, are essential for RcGTA-mediated gene acquisition. This paper gives genetic and biochemical evidence that RcGTA-borne DNA entry into cells requires the ComEC and ComF putative DNA transport proteins and genetic evidence that putative cytoplasmic ComM protein of unknown function is required for recipient capability. Furthermore, the master regulator of RcGTA production in <1% of a cell population, CtrA, which is also required for gene acquisition in recipient cells, is expressed in the vast majority of the population. Our results indicate that RcGTA-mediated gene transfer combines key aspects of two bacterial horizontal gene transfer mechanisms, where donor DNA is packaged in transducing phage-like particles and recipient cells take up DNA using natural transformation-related machinery. Both of these differentiated subsets of a culture population, donors and recipients, are dependent on the same response regulator, CtrA. IMPORTANCE Horizontal gene transfer (HGT) is a major driver of bacterial evolution and adaptation to environmental stresses. Traits such as antibiotic resistance or metabolic properties can be transferred between bacteria via HGT; thus, HGT can have a tremendous effect on the fitness of a bacterial population. The three classically described HGT mechanisms are conjugation, transformation, and phage-mediated transduction. More recently, the HGT factor GTA was described, where random pieces of producing cell genome are packaged into phage-like particles that deliver DNA to recipient cells. In this report, we show that transport of

  5. Magnetic molecularly imprinted polymers synthesized by surface-initiated reversible addition-fragmentation chain transfer polymerization for the enrichment and determination of synthetic estrogens in aqueous solution.

    PubMed

    Chen, Fangfang; Zhang, Jingjing; Wang, Minjun; Kong, Jie

    2015-08-01

    Magnetic molecularly imprinted polymers have attracted significant interest because of their multifunctionality of selective recognition of target molecules and rapid magnetic response. In this contribution, magnetic molecularly imprinted polymers were synthesized via surface-initiated reversible addition addition-fragmentation chain transfer polymerization using diethylstilbestrol as the template for the enrichment of synthetic estrogens. The uniform imprinted surface layer and the magnetic property of the magnetic molecularly imprinted polymers favored a fast binding kinetics and rapid analysis of target molecules. The static and selective binding experiments demonstrated a desirable adsorption capacity and good selectivity of the magnetic molecularly imprinted polymers in comparison to magnetic non-molecularly imprinted polymers. Accordingly, a corresponding analytical method was developed in which magnetic molecularly imprinted polymers were employed as magnetic solid-phase extraction materials for the concentration and determination of four synthetic estrogens (diethylstilbestrol, hexestrol, dienestrol, and bisphenol A) in fish pond water. The recoveries of these synthetic estrogens in spiked fish pond water samples ranged from 61.2 to 99.1% with a relative standard deviation of lower than 6.3%. This study provides a versatile approach to prepare well-defined magnetic molecularly imprinted polymers sorbents for the analysis of synthetic estrogens in water solution. PMID:25989155

  6. Asymmetric Synthesis and Binding Study of New Long-Chain HPA-12 Analogues as Potent Ligands of the Ceramide Transfer Protein CERT.

    PubMed

    Ďuriš, Andrej; Daïch, Adam; Santos, Cécile; Fleury, Laurence; Ausseil, Frédéric; Rodriguez, Frédéric; Ballereau, Stéphanie; Génisson, Yves; Berkeš, Dušan

    2016-05-01

    A series of 12 analogues of the Cer transfer protein (CERT) antagonist HPA-12 with long aliphatic chains were prepared as their (1R,3S)-syn and (1R,3R)-anti stereoisomers from pivotal chiral oxoamino acids. The enantioselective access to these intermediates as well as their ensuing transformation relied on a practical crystallization-induced asymmetric transformation (CIAT) process. Sonogashira coupling followed by triple bond reduction and thiophene ring hydrodesulfurization (HDS) into the corresponding alkane moieties was then implemented to complete the synthetic routes delivering the targeted HPA-12 analogues in concise 4- to 6-step reaction sequences. Ten compounds were evaluated regarding their ability to bind to the CERT START domain by using the recently developed time-resolved FRET-based homogeneous (HTR-FRET) binding assay. The introduction of a lipophilic appendage on the phenyl moiety led to an overall 10- to 1000-fold enhancement of the protein binding, with the highest effect being observed for a n-hexyl residue in the meta position. The importance of the phenyl ring for the activity was indicated by the reduced potency of the 3-deoxyphytoceramide aliphatic analogues. The 1,3-syn stereoisomers were systematically more potent than their 1,3-anti analogues. In silico studies were used to rationalized these trends, leading to a model of protein recognition coherent with the stronger binding of (1R,3S)-syn HPAs. PMID:27031925

  7. Thermally conductive, electrically insulating and melt-processable polystyrene/boron nitride nanocomposites prepared by in situ reversible addition fragmentation chain transfer polymerization.

    PubMed

    Huang, Xingyi; Wang, Shen; Zhu, Ming; Yang, Ke; Jiang, Pingkai; Bando, Yoshio; Golberg, Dmitri; Zhi, Chunyi

    2015-01-01

    Thermally conductive and electrically insulating polymer/boron nitride (BN) nanocomposites are highly attractive for various applications in many thermal management fields. However, so far most of the preparation methods for polymer/BN nanocomposites have usually caused difficulties in the material post processing. Here, an in situ grafting approach is designed to fabricate thermally conductive, electrically insulating and post-melt processable polystyrene (PS)/BN nanosphere (BNNS) nanocomposites by initiating styrene (St) on the surface functionalized BNNSs via reversible addition fragmentation chain transfer polymerization. The nanocomposites exhibit significantly enhanced thermal conductivity. For example, at a St/BN feeding ratio of 5:1, an enhancement ratio of 1375% is achieved in comparison with pure PS. Moreover, the dielectric properties of the nanocomposites show a desirable weak dependence on frequency, and the dielectric loss tangent of the nanocomposites remains at a very low level. More importantly, the nanocomposites can be subjected to multiple melt processing to form different shapes. Our method can become a universal approach to prepare thermally conductive, electrically insulating and melt-processable polymer nanocomposites with diverse monomers and nanofillers. PMID:25493655

  8. Thermally conductive, electrically insulating and melt-processable polystyrene/boron nitride nanocomposites prepared by in situ reversible addition fragmentation chain transfer polymerization

    NASA Astrophysics Data System (ADS)

    Huang, Xingyi; Wang, Shen; Zhu, Ming; Yang, Ke; Jiang, Pingkai; Bando, Yoshio; Golberg, Dmitri; Zhi, Chunyi

    2015-01-01

    Thermally conductive and electrically insulating polymer/boron nitride (BN) nanocomposites are highly attractive for various applications in many thermal management fields. However, so far most of the preparation methods for polymer/BN nanocomposites have usually caused difficulties in the material post processing. Here, an in situ grafting approach is designed to fabricate thermally conductive, electrically insulating and post-melt processable polystyrene (PS)/BN nanosphere (BNNS) nanocomposites by initiating styrene (St) on the surface functionalized BNNSs via reversible addition fragmentation chain transfer polymerization. The nanocomposites exhibit significantly enhanced thermal conductivity. For example, at a St/BN feeding ratio of 5:1, an enhancement ratio of 1375% is achieved in comparison with pure PS. Moreover, the dielectric properties of the nanocomposites show a desirable weak dependence on frequency, and the dielectric loss tangent of the nanocomposites remains at a very low level. More importantly, the nanocomposites can be subjected to multiple melt processing to form different shapes. Our method can become a universal approach to prepare thermally conductive, electrically insulating and melt-processable polymer nanocomposites with diverse monomers and nanofillers.

  9. 100-N Area Strontium-90 Treatability Demonstration Project: Food Chain Transfer Studies for Phytoremediation Along the 100-N Columbia River Riparian Zone

    SciTech Connect

    Fellows, Robert J.; Fruchter, Jonathan S.; Driver, Crystal J.

    2009-04-01

    Strontium-90 (90Sr) exceeds the U.S. Environmental Protection Agency’s drinking water standards for groundwater (8 picocuries/L) by as much as a factor of 1000 at several locations within the Hanford 100-N Area and along the 100-N Area Columbia River shoreline). Phytoextraction, a managed remediation technology in which plants or integrated plant/rhizosphere systems are employed to phytoextract and/or sequester 90Sr, is being considered as a potential remediation system along the riparian zone of the Columbia River as part of a treatment train that includes an apatite barrier to immobilize groundwater transport of 90Sr. Phytoextraction would employ coyote willow (Salix exigua) to extract 90Sr from the vadose zone soil and aquifer sediments (phytoextraction) and filter 90Sr (rhizofiltration) from the shallow groundwater along the riparian zone of the Columbia River. The stem and foliage of coyote willows accumulating 90Sr may present not only a mechanism to remove the contaminant but also can be viewed as a source of nutrition for natural herbivores, therefore becoming a potential pathway for the isotope to enter the riparian food chain. Engineered barriers such as large and small animal fencing constructed around the field plot will control the intrusion of deer, rodents, birds, and humans. These efforts, however, will have limited effect on mobile phytophagous insects. Therefore, this study was undertaken to determine the potential for food chain transfer by insects prior to placement of the remediation technology at 100-N. Insect types include direct consumers of the sap or liquid content of the plants vascular system (xylem and phloem) by aphids as well as those that would directly consume the plant foliage such as the larvae (caterpillars) of Lepidoptera species. Heavy infestations of aphids feeding on the stems and leaves of willows growing in 90Sr-contaminated soil can accumulate a small amount (~0.15 ± 0.06%) of the total label removed from the soil by

  10. Enhanced heat transfer through filler-polymer interface by surface-coupling agent in heat-dissipation material: A non-equilibrium molecular dynamics study

    SciTech Connect

    Tanaka, Kouichi; Ogata, Shuji; Kobayashi, Ryo; Tamura, Tomoyuki; Kitsunezuka, Masashi; Shinma, Atsushi

    2013-11-21

    Developing a composite material of polymers and micrometer-sized fillers with higher heat conductance is crucial to realize modular packaging of electronic components at higher densities. Enhancement mechanisms of the heat conductance of the polymer-filler interfaces by adding the surface-coupling agent in such a polymer composite material are investigated through the non-equilibrium molecular dynamics (MD) simulation. A simulation system is composed of α-alumina as the filler, bisphenol-A epoxy molecules as the polymers, and model molecules for the surface-coupling agent. The inter-atomic potential between the α-alumina and surface-coupling molecule, which is essential in the present MD simulation, is constructed to reproduce the calculated energies with the electronic density-functional theory. Through the non-equilibrium MD simulation runs, we find that the thermal resistance at the interface decreases significantly by increasing either number or lengths of the surface-coupling molecules and that the effective thermal conductivity of the system approaches to the theoretical value corresponding to zero thermal-resistance at the interface. Detailed analyses about the atomic configurations and local temperatures around the interface are performed to identify heat-transfer routes through the interface.

  11. A high-throughput fluorescence resonance energy transfer (FRET)-based endothelial cell apoptosis assay and its application for screening vascular disrupting agents

    SciTech Connect

    Zhu, Xiaoming; Fu, Afu; Luo, Kathy Qian

    2012-02-24

    Highlights: Black-Right-Pointing-Pointer An endothelial cell apoptosis assay using FRET-based biosensor was developed. Black-Right-Pointing-Pointer The fluorescence of the cells changed from green to blue during apoptosis. Black-Right-Pointing-Pointer This method was developed into a high-throughput assay in 96-well plates. Black-Right-Pointing-Pointer This assay was applied to screen vascular disrupting agents. -- Abstract: In this study, we developed a high-throughput endothelial cell apoptosis assay using a fluorescence resonance energy transfer (FRET)-based biosensor. After exposure to apoptotic inducer UV-irradiation or anticancer drugs such as paclitaxel, the fluorescence of the cells changed from green to blue. We developed this method into a high-throughput assay in 96-well plates by measuring the emission ratio of yellow fluorescent protein (YFP) to cyan fluorescent protein (CFP) to monitor the activation of a key protease, caspase-3, during apoptosis. The Z Prime factor for this assay was above 0.5 which indicates that this assay is suitable for a high-throughput analysis. Finally, we applied this functional high-throughput assay for screening vascular disrupting agents (VDA) which could induce endothelial cell apoptosis from our in-house compounds library and dioscin was identified as a hit. As this assay allows real time and sensitive detection of cell apoptosis, it will be a useful tool for monitoring endothelial cell apoptosis in living cell situation and for identifying new VDA candidates via a high-throughput screening.

  12. Phosphate Concentration and the Putative Sensor Kinase Protein CckA Modulate Cell Lysis and Release of the Rhodobacter capsulatus Gene Transfer Agent

    PubMed Central

    Westbye, A. B.; Leung, M. M.; Florizone, S. M.; Taylor, T. A.; Johnson, J. A.; Fogg, P. C.

    2013-01-01

    The gene transfer agent of Rhodobacter capsulatus (RcGTA) is a bacteriophage-like genetic element with the sole known function of horizontal gene transfer. Homologues of RcGTA genes are present in many members of the alphaproteobacteria and may serve an important role in microbial evolution. Transcription of RcGTA genes is induced as cultures enter the stationary phase; however, little is known about cis-active sequences. In this work, we identify the promoter of the first gene in the RcGTA structural gene cluster. Additionally, gene transduction frequency depends on the growth medium, and the reason for this is not known. We report that millimolar concentrations of phosphate posttranslationally inhibit the lysis-dependent release of RcGTA from cells in both a complex medium and a defined medium. Furthermore, we found that cell lysis requires the genes rcc00555 and rcc00556, which were expressed and studied in Escherichia coli to determine their predicted functions as an endolysin and holin, respectively. Production of RcGTA is regulated by host systems, including a putative histidine kinase, CckA, and we found that CckA is required for maximal expression of rcc00555 and for maturation of RcGTA to yield gene transduction-functional particles. PMID:23995641

  13. Photoinduced electron transfer in ordered polymers

    SciTech Connect

    Jones, G. II.

    1990-10-20

    Photochemical studies on organic polymers or biopolymers (particularly synthetic peptides) that have been modified by covalent attachment (or other means of binding) of organic chromophores and electron transfer agents are described. Specific projects involve are: peptide conjugates bearing electroactive residues such as tryptophan and specifically labeled at the N- or C-terminus of peptide chains; the electrostatic binding of organic dyes to poly-electrolytes (polyacrylates) for which the formation of dimeric aggregates of bound dye that display unusual photophysical and electron transfer properties is important; a study of the binding of dyes and electron transfer agents to the protein mimic,'' polyvinyl-2-pyrrolidinone (PVP), in hydrophobic domains that depend on specific H-bond interaction; and completion of an earlier study having to do with the triplet state properties of charge-transfer (CT) complexes of a high potential quinone and various electron donors (investigation of the properties of triplet (contact) radical-ion pairs). 13 refs., 5 figs., 2 tabs.

  14. Electrospun regenerated cellulose nanofibrous membranes surface-grafted with polymer chains/brushes via the atom transfer radical polymerization method for catalase immobilization.

    PubMed

    Feng, Quan; Hou, Dayin; Zhao, Yong; Xu, Tao; Menkhaus, Todd J; Fong, Hao

    2014-12-10

    In this study, an electrospun regenerated cellulose (RC) nanofibrous membrane with fiber diameters of ∼200-400 nm was prepared first; subsequently, 2-hydroxyethyl methacrylate (HEMA), 2-dimethylaminoethyl methacrylate (DMAEMA), and acrylic acid (AA) were selected as the monomers for surface grafting of polymer chains/brushes via the atom transfer radical polymerization (ATRP) method. Thereafter, four nanofibrous membranes (i.e., RC, RC-poly(HEMA), RC-poly(DMAEMA), and RC-poly(AA)) were explored as innovative supports for immobilization of an enzyme of bovine liver catalase (CAT). The amount/capacity, activity, stability, and reusability of immobilized catalase were evaluated, and the kinetic parameters (Vmax and Km) for immobilized and free catalase were determined. The results indicated that the respective amounts/capacities of immobilized catalase on RC-poly(HEMA) and RC-poly(DMAEMA) nanofibrous membranes reached 78 ± 3.5 and 67 ± 2.7 mg g(-1), which were considerably higher than the previously reported values. Meanwhile, compared to that of free CAT (i.e., 18 days), the half-life periods of RC-CAT, RC-poly(HEMA)-CAT, RC-poly(DMAEMA)-CAT, and RC-poly(AA)-CAT were 49, 58, 56, and 60 days, respectively, indicating that the storage stability of immobilized catalase was also significantly improved. Furthermore, the immobilized catalase exhibited substantially higher resistance to temperature variation (tested from 5 to 70 °C) and lower degree of sensitivity to pH value (tested from 4.0 and 10.0) than the free catalase. In particular, according to the kinetic parameters of Vmax and Km, the nanofibrous membranes of RC-poly(HEMA) (i.e., 5102 μmol mg(-1) min(-1) and 44.89 mM) and RC-poly(DMAEMA) (i.e., 4651 μmol mg(-1) min(-1) and 46.98 mM) had the most satisfactory biocompatibility with immobilized catalase. It was therefore concluded that the electrospun RC nanofibrous membranes surface-grafted with 3-dimensional nanolayers of polymer chains/brushes would be

  15. Exploration on natural product anibamine side chain modification toward development of novel CCR5 antagonists and potential anti-prostate cancer agents.

    PubMed

    Xu, Guoyan G; Zaidi, Saheem A; Zhang, Feng; Singh, Shilpa; Raborg, Thomas J; Yuan, Yunyun; Zhang, Yan

    2015-09-01

    Prostate cancer is one of the leading causes of death among males in the world. Prostate cancer cells have been shown to express upregulated chemokine receptor CCR5, a G protein-coupled receptor (GPCR) that relates to the inflammation process. Anibamine, a natural product containing a pyridine ring and two aliphatic side chains, was shown to carry a binding affinity of 1 μM at CCR5 as an antagonist with potential anti-cancer activity. However, it is not drug-like according to the Lipinski's rule of five mainly due to its two long aliphatic side chains. In our effort to improve its drug-like property, a series of anibamine derivatives were designed and synthesized by placement of aromatic side chains through an amide linkage to the pyridine ring. The newly synthesized compounds were tested for their CCR5 affinity and antagonism, and potential anti-proliferation activity against prostate cancer cell lines. Basal cytotoxicity was finally studied for compounds showing potent anti-proliferation activity. It was found that compounds with hydrophobic substitutions on the aromatic systems seemed to carry more promising CCR5 binding and prostate cancer cell proliferation inhibition activities. PMID:26096680

  16. Understanding Transferable Supply Chain Lessons and Practices to a “High-Tech” Industry Using Guidelines from a Primary Sector Industry: A Case Study in the Food Industry Supply Chain

    PubMed Central

    Coronado Mondragon, Adrian E.; Coronado, Etienne S.

    2015-01-01

    Flexibility and innovation at creating shapes, adapting processes, and modifying materials characterize composites materials, a “high-tech” industry. However, the absence of standard manufacturing processes and the selection of materials with defined properties hinder the configuration of the composites materials supply chain. An interesting alternative for a “high-tech” industry such as composite materials would be to review supply chain lessons and practices in “low-tech” industries such as food. The main motivation of this study is to identify lessons and practices that comprise innovations in the supply chain of a firm in a perceived “low-tech” industry that can be used to provide guidelines in the design of the supply chain of a “high-tech” industry, in this case composite materials. This work uses the case study/site visit with analogy methodology to collect data from a Spanish leading producer of fresh fruit juice which is sold in major European markets and makes use of a cold chain. The study highlights supply base management and visibility/traceability as two elements of the supply chain in a “low-tech” industry that can provide guidelines that can be used in the configuration of the supply chain of the composite materials industry. PMID:25821848

  17. Understanding transferable supply chain lessons and practices to a "high-tech" industry using guidelines from a primary sector industry: a case study in the food industry supply chain.

    PubMed

    Coronado Mondragon, Adrian E; Coronado Mondragon, Christian E; Coronado, Etienne S

    2015-01-01

    Flexibility and innovation at creating shapes, adapting processes, and modifying materials characterize composites materials, a "high-tech" industry. However, the absence of standard manufacturing processes and the selection of materials with defined properties hinder the configuration of the composites materials supply chain. An interesting alternative for a "high-tech" industry such as composite materials would be to review supply chain lessons and practices in "low-tech" industries such as food. The main motivation of this study is to identify lessons and practices that comprise innovations in the supply chain of a firm in a perceived "low-tech" industry that can be used to provide guidelines in the design of the supply chain of a "high-tech" industry, in this case composite materials. This work uses the case study/site visit with analogy methodology to collect data from a Spanish leading producer of fresh fruit juice which is sold in major European markets and makes use of a cold chain. The study highlights supply base management and visibility/traceability as two elements of the supply chain in a "low-tech" industry that can provide guidelines that can be used in the configuration of the supply chain of the composite materials industry. PMID:25821848

  18. ALTERNATE FOOD-CHAIN TRANSFER OF THE TOXIN LINKED TO AVIAN VACUOLAR MYELINOPATHY AND IMPLICATIONS FOR THE ENDANGERED FLORIDA SNAIL KITE (ROSTRHAMUS SOCIABILIS).

    PubMed

    Dodd, Shelley R; Haynie, Rebecca S; Williams, Susan M; Wilde, Susan B

    2016-04-28

    Avian vacuolar myelinopathy (AVM) is a neurologic disease causing recurrent mortality of Bald Eagles ( Haliaeetus leucocephalus ) and American Coots ( Fulica americana ) at reservoirs and small impoundments in the southern US. Since 1994, AVM is considered the cause of death for over 170 Bald Eagles and thousands of American Coots and other species of wild birds. Previous studies link the disease to an uncharacterized toxin produced by a recently described cyanobacterium, Aetokthonos hydrillicola gen. et sp. nov. that grows epiphytically on submerged aquatic vegetation (SAV). The toxin accumulates, likely in the gastrointestinal tract of waterbirds that consume SAV, and birds of prey are exposed when feeding on the moribund waterbirds. Aetokthonos hydrillicola has been identified in all reservoirs where AVM deaths have occurred and was identified growing abundantly on an exotic SAV hydrilla ( Hydrilla verticillata ) in Lake Tohopekaliga (Toho) in central Florida. Toho supports a breeding population of a federally endangered raptor, the Florida Snail Kite ( Rostrhamus sociabilis ) and a dense infestation of an exotic herbivorous aquatic snail, the island applesnail ( Pomacea maculata ), a primary source of food for resident Snail Kites. We investigated the potential for transmission in a new food chain and, in laboratory feeding trials, confirmed that the AVM toxin was present in the hydrilla/A. hydrillicola matrix collected from Toho. Additionally, laboratory birds that were fed apple snails feeding on hydrilla/A. hydrillicola material from a confirmed AVM site displayed clinical signs (3/5), and all five developed brain lesions unique to AVM. This documentation of AVM toxin in central Florida and the demonstration of AVM toxin transfer through invertebrates indicate a significant risk to the already diminished population of endangered Snail Kites. PMID:26981686

  19. Disruption of neuronal CXCR4 function by opioids: preliminary evidence of Ferritin Heavy Chain as a potential etiological agent in neuroAIDS

    PubMed Central

    Pitcher, Jonathan; Shimizu, Saori; Meucci, Olimpia

    2010-01-01

    The chemokine CXCL12 and its receptor, CXCR4, regulate neuronal migration, differentiation, and survival. Alterations of CXCL12/CXCR4 signaling are implicated in different neuropathologies, including the neurological complications of HIV infection. Opiates are important co-factors for progression to neuroAIDS and can disrupt the CXCL12/CXCR4 axis in vitro and in vivo. This paper will review recently identified mechanisms of opiate-induced CXCR4 impairment in neurons and introduce results from pilot studies in human brain tissue, which highlight the role of the protein ferritin heavy chain in HIV neuropathology in patients with history of drug abuse. PMID:20627326

  20. A high-throughput fluorescence resonance energy transfer (FRET)-based endothelial cell apoptosis assay and its application for screening vascular disrupting agents.

    PubMed

    Zhu, Xiaoming; Fu, Afu; Luo, Kathy Qian

    2012-02-24

    In this study, we developed a high-throughput endothelial cell apoptosis assay using a fluorescence resonance energy transfer (FRET)-based biosensor. After exposure to apoptotic inducer UV-irradiation or anticancer drugs such as paclitaxel, the fluorescence of the cells changed from green to blue. We developed this method into a high-throughput assay in 96-well plates by measuring the emission ratio of yellow fluorescent protein (YFP) to cyan fluorescent protein (CFP) to monitor the activation of a key protease, caspase-3, during apoptosis. The Z' factor for this assay was above 0.5 which indicates that this assay is suitable for a high-throughput analysis. Finally, we applied this functional high-throughput assay for screening vascular disrupting agents (VDA) which could induce endothelial cell apoptosis from our in-house compounds library and dioscin was identified as a hit. As this assay allows real time and sensitive detection of cell apoptosis, it will be a useful tool for monitoring endothelial cell apoptosis in living cell situation and for identifying new VDA candidates via a high-throughput screening. PMID:22290227

  1. O-GlcNAcylation of the Plum pox virus capsid protein catalyzed by SECRET AGENT: characterization of O-GlcNAc sites by electron transfer dissociation mass spectrometry.

    PubMed

    Kim, Young-Cheon; Udeshi, Namrata D; Balsbaugh, Jeremy L; Shabanowitz, Jeffrey; Hunt, Donald F; Olszewski, Neil E

    2011-03-01

    The capsid protein of Plum pox virus (PPV-CP) is modified with O-linked β-N-acetylglucosamine (O-GlcNAc). In Arabidopsis thaliana this modification is made by an O-GlcNAc transferase named SECRET AGENT (SEC). Modification of PPV-CP by SEC is hypothesized to have a direct role in the infection process, because virus titer and rate of spread are reduced in SEC mutants. Previous studies used deletion mapping and site-directed mutagenesis to identify four O-GlcNAc sites on the capsid protein that are modified by Escherichia coli-expressed SEC. The infection process was not affected when two of these sites were mutated suggesting that O-GlcNAcylation of these sites does not have a significant role in the infection process or that a subset of the modifications is sufficient. Since it is possible that the mutational mapping approach missed or incorrectly identified O-GlcNAc sites, the modifications produced by E. coli-expressed SEC were characterized using mass spectrometry. O-GlcNAcylated peptides were enzymatically tagged with galactose, the products were enriched on immobilized Ricinus communis agglutinin I and sequenced by electron transfer dissociation (ETD) mass spectrometry. Five O-GlcNAc sites on PPV-CP were identified. Two of these sites were not identified in by the previous mutational mapping. In addition, one site previously predicted by mutation mapping was not detected, but modification of this site was not supported when the mutation mapping was repeated. This study suggests that mapping modification sites by ETD mass spectrometry is more comprehensive and accurate than mutational mapping. PMID:20676902

  2. Liposome encapsulation of chelating agents

    DOEpatents

    Rahman, Yueh Erh

    1976-01-13

    A method for transferring a chelating agent across a cellular membrane by encapsulating the charged chelating agent within liposomes and carrying the liposome-encapsulated chelating agent to the cellular membrane where the liposomes containing the chelating agent will be taken up by the cells, thereby transferring the chelating agent across the cellular membrane. A chelating agent can be introduced into the interior of a cell of a living organism wherein the liposomes will be decomposed, releasing the chelating agent to the interior of the cell. The released chelating agent will complex intracellularly deposited toxic heavy metals, permitting the more soluble metal complex to transfer across the cellular membrane from the cell and subsequently be removed from the living organism.

  3. Reinforcement learning in supply chains.

    PubMed

    Valluri, Annapurna; North, Michael J; Macal, Charles M

    2009-10-01

    Effective management of supply chains creates value and can strategically position companies. In practice, human beings have been found to be both surprisingly successful and disappointingly inept at managing supply chains. The related fields of cognitive psychology and artificial intelligence have postulated a variety of potential mechanisms to explain this behavior. One of the leading candidates is reinforcement learning. This paper applies agent-based modeling to investigate the comparative behavioral consequences of three simple reinforcement learning algorithms in a multi-stage supply chain. For the first time, our findings show that the specific algorithm that is employed can have dramatic effects on the results obtained. Reinforcement learning is found to be valuable in multi-stage supply chains with several learning agents, as independent agents can learn to coordinate their behavior. However, learning in multi-stage supply chains using these postulated approaches from cognitive psychology and artificial intelligence take extremely long time periods to achieve stability which raises questions about their ability to explain behavior in real supply chains. The fact that it takes thousands of periods for agents to learn in this simple multi-agent setting provides new evidence that real world decision makers are unlikely to be using strict reinforcement learning in practice. PMID:19885962

  4. Respiratory chain supercomplexes.

    PubMed

    Schägger, H

    2001-01-01

    Respiratory chain supercomplexes have been isolated from mammalian and yeast mitochondria, and bacterial membranes. Functional roles of respiratory chain supercomplexes are catalytic enhancement, substrate channelling, and stabilization of complex I by complex III in mammalian cells. Bacterial supercomplexes are characterized by their relatively high detergent-stability compared to yeast or mammalian supercomplexes that are stable to sonication. The mobility of substrate cytochrome c increases in the order bacterial, yeast, and mammalian respiratory chain. In bacterial supercomplexes, the electron transfer between complexes III and IV involves movement of the mobile head of a tightly bound cytochrome c, whereas the yeast S. cerevisiae seems to use substrate channelling of a mobile cytochrome c, and mammalian respiratory chains have been described to use a cytochrome c pool. Dimeric ATP synthase seems to be specific for mitochondrial OXPHOS systems. Monomeric complex V was found in Acetobacterium woodii and Paracoccus denitrificans. PMID:11798023

  5. Specific dimerization of the light chains of human immunoglobulin.

    PubMed

    Stevenson, G T; Straus, D

    1968-07-01

    1. The light chains of human immunoglobulin were allowed to dimerize in vitro on removal of the dispersing agents acetic acid or urea. 2. On electrophoresis in polyacrylamide gel at pH8.8 the dimers yielded up to nine regularly spaced bands. This approximates to the number of electrophoretic components known to occur among the monomers. 3. Single electrophoretic components of the dimers were isolated from the gel, dissociated into monomers, and subjected as such to electrophoresis in urea-containing gels. Each gave two adjacent bands. 4. Similarly, after all the light chains as monomers had been subjected to electrophoresis in urea-containing gels, single electrophoretic components were isolated and allowed to dimerize. When examined now as dimers in the absence of urea, each component gave two adjacent bands. 5. These findings are explicable on the following basis. (a) The dimerization of the light chains is specific, at least inasmuch as it occurs between monomers of the same electrophoretic mobilities. (b) With the buffer constant, different light chains undergo different changes in net charge on being transferred from urea-containing to urea-free solution; in this way two different chains of the same initial charge can acquire a charge difference of 1. 6. Experiments with Bence-Jones proteins and other homogeneous light chains gave results substantiating the conclusions (a) and (b). PMID:4174431

  6. End-Functionalized Polymers and Junction-Functionalized Diblock Copolymers Via RAFT Chain Extension with Maleimido Monomers

    PubMed Central

    Henry, Scott M.; Convertine, Anthony J.; Benoit, Danielle S. W.; Hoffman, Allan S.; Stayton, Patrick S.

    2010-01-01

    A new strategy is described for functionalizing the ω-terminal end of polymers synthesized by reversible addition–fragmentation chain transfer (RAFT) polymerization that provides spatially controlled bioconjugation sites. Traditional methods for preparing ω-functional polymers require the reduction of the RAFT chain-transfer agent to yield secondary or tertiary thiols of low reactivity or the synthesis of novel chain-transfer agents that contain reactive groups. As an additional strategy, N-substituted maleimido monomers have been used in a modified block polymerization to add a single maleimido unit onto the RAFT polymer with nearly quantitative efficiency. Unique reactive groups contained in the N-substituent are thereby added to the ω-terminal end of the polymer and are subsequently available for conjugation reactions. This technique has been demonstrated using N-(2-aminoethyl)maleimide trifluoroacetate to introduce a single primary amine to the ω-terminus of poly(dimethy-laminoethyl methacrylate) and poly(N-isopropyl acrylamide) and to a specialized block copolymer for siRNA delivery. Evidence for retention of functional RAFT endgroups is provided by synthesis results where chain-extended polyDMAEMA (Mn = 10 600 g/mol, Mw/Mn = 1.14) was used as a macro chain transfer agent for the polymerization of styrene, yielding a diblock polymer of low polydispersity (Mn = 20 300 g/mol, Mw/Mn = 1.11). It is thus also possible to construct diblock copolymers with a bioconjugation site precisely located at the junction between the two blocks. The chain-extended polymers are functionalized with an amine-reactive fluorescent dye or folic acid at conjugation efficiencies of 86 and 94%, respectively. The versatile chain-extension technique described here offers unique opportunities for the synthesis of well-defined polymeric conjugates to molecules of biological and targeting interest. PMID:19480416

  7. Ernst Chain: a great man of science.

    PubMed

    Kardos, Nelson; Demain, Arnold L

    2013-08-01

    This paper is a tribute to the scientific accomplishments of Ernst Chain and the influence he exerted over the fields of industrial microbiology and biotechnology. Chain is the father of the modern antibiotic era and all the benefits that these therapeutic agents have brought, i.e., longer life spans, greater levels of public health, widespread modern surgery, and control of debilitating infectious diseases, including tuberculosis, gonorrhea, syphilis, etc. Penicillin was the first antibiotic to become commercially available, and its use ushered in the age of antibiotics. The discovery of penicillin's bactericidal action had been made by Alexander Fleming in London in 1928. After publishing his observations in 1929, no further progress was made until the work was picked up in 1939 by scientists at Oxford University. The group was headed by Howard Florey, and Chain was the group's lead scientist. Chain was born and educated in Germany, and he fled in 1933 as a Jewish refugee from Nazism to England. Other important members of the Oxford research team were Norman Heatley and Edward Abraham. The team was able to produce and isolate penicillin under conditions of scarce resources and many technical challenges. Sufficient material was collected and tested on mice to successfully demonstrate penicillin's bactericidal action on pathogens, while being nontoxic to mammals. Chain directed the microbiological methods for producing penicillin and the chemical engineering methods to extract the material. This technology was transferred to US government facilities in 1941 for commercial production of penicillin, becoming an important element in the Allied war effort. In 1945, the Nobel Prize for medicine was shared by Fleming, Florey, and Chain in recognition of their work in developing penicillin as a therapeutic agent. After World War II, Chain tried to persuade the British government to fund a new national antibiotic industry with both research and production facilities. As

  8. Diagonalization of transfer matrix of supersymmetry U{sub q}(sl-caret(M+1|N+1)) chain with a boundary

    SciTech Connect

    Kojima, Takeo

    2013-04-15

    We study the supersymmetry U{sub q}(sl-caret(M+1|N+1)) analogue of the supersymmetric t-J model with a boundary. Our approach is based on the algebraic analysis method of solvable lattice models. We diagonalize the commuting transfer matrix by using the bosonizations of the vertex operators associated with the quantum affine supersymmetry U{sub q}(sl-caret(M+1|N+1)).

  9. Electron-lattice interactions strongly renormalize the charge-transfer energy in the spin-chain cuprate Li2CuO2

    DOE PAGESBeta

    Johnston, Steve; Monney, Claude; Bisogni, Valentina; Zhou, Ke-Jin; Kraus, Roberto; Behr, Günter; Strocov, Vladimir N.; Málek, Jiři; Drechsler, Stefan-Ludwig; Geck, Jochen; et al

    2016-02-17

    Strongly correlated insulators are broadly divided into two classes: Mott–Hubbard insulators, where the insulating gap is driven by the Coulomb repulsion U on the transition-metal cation, and charge-transfer insulators, where the gap is driven by the charge-transfer energy Δ between the cation and the ligand anions. The relative magnitudes of U and Δ determine which class a material belongs to, and subsequently the nature of its low-energy excitations. These energy scales are typically understood through the local chemistry of the active ions. Here we show that the situation is more complex in the low-dimensional charge-transfer insulator Li2CuO2, where Δ hasmore » a large non-electronic component. Combining resonant inelastic X-ray scattering with detailed modelling, we determine how the elementary lattice, charge, spin and orbital excitations are entangled in this material. This results in a large lattice-driven renormalization of Δ, which significantly reshapes the fundamental electronic properties of Li2CuO2.« less

  10. Electron-lattice interactions strongly renormalize the charge-transfer energy in the spin-chain cuprate Li2CuO2

    PubMed Central

    Johnston, Steve; Monney, Claude; Bisogni, Valentina; Zhou, Ke-Jin; Kraus, Roberto; Behr, Günter; Strocov, Vladimir N.; Málek, Jiři; Drechsler, Stefan-Ludwig; Geck, Jochen; Schmitt, Thorsten; van den Brink, Jeroen

    2016-01-01

    Strongly correlated insulators are broadly divided into two classes: Mott–Hubbard insulators, where the insulating gap is driven by the Coulomb repulsion U on the transition-metal cation, and charge-transfer insulators, where the gap is driven by the charge-transfer energy Δ between the cation and the ligand anions. The relative magnitudes of U and Δ determine which class a material belongs to, and subsequently the nature of its low-energy excitations. These energy scales are typically understood through the local chemistry of the active ions. Here we show that the situation is more complex in the low-dimensional charge-transfer insulator Li2CuO2, where Δ has a large non-electronic component. Combining resonant inelastic X-ray scattering with detailed modelling, we determine how the elementary lattice, charge, spin and orbital excitations are entangled in this material. This results in a large lattice-driven renormalization of Δ, which significantly reshapes the fundamental electronic properties of Li2CuO2. PMID:26884151

  11. Measurements of sup 129 I in human and bovine thyroids in Europe--transfer of sup 129 I into the food chain

    SciTech Connect

    Handl, J.; Pfau, A.; Huth, F.W. )

    1990-05-01

    Bovine thyroid glands from different countries in Europe and human thyroid glands from Lower Saxony (Federal Republic of Germany) show isotopic 129I/127I ratios of 2.1 X 10(-9) to 8.2 X 10(-8) for cattle and 2.1 X 10(-9) to 8 X 10(-8) in humans. These values give information about the concentration of fallout 129I in Europe since most of these glands were collected in areas without nuclear facilities. Some of the human thyroids were collected after the Chernobyl accident between May 1986 and February 1988. Results obtained from human thyroids taken in some locations of Lower Saxony show no significant increase of the 129I during this time. Higher concentrations of 129I were only found in cattle grazing in the vicinity of a reprocessing plant in Mol, Belgium. Samples of soil, vegetation, milk, and water from this area contained higher than normal concentrations of 129I. The long-term transfer of radioiodine from the soil to the plant and the translocation within the soil were studied using a soil monolith with a 129I-contaminated surface. During the 4 y of the experiment, the transfer factor plant/soil decreased from 0.3 to 2.2 X 10(-3). Soil samples taken in 5-cm steps to a depth of 30 cm then at 40 and 50 cm depths showed that the transport of radioiodine to lower layers proceeds very slowly. In an in-vivo study with a dairy cow, the transfer of radioiodine from feed to milk to cow meat and to pig thyroid gland was followed for 53 d using 129I-labeled pasture grass contaminated via roots. A part of the milk obtained from the cow was fed to a pig as a substitute for humans. The mean value of the transfer factor milk/feed was 2.4 X 10(-3) d kg-1. The values of the transfer factor cow meat/feed obtained for different muscle cuts and organs (excluding thyroid) ranged between 3.0 X 10(-4) (kidney) and 5.4 X 10(-2) d kg-1 f.w.

  12. Agent Orange

    MedlinePlus

    ... Index Agent Orange Agent Orange Home Facts about Herbicides Veterans' Diseases Birth Defects Benefits Exposure Locations Provider ... millions of gallons of Agent Orange and other herbicides on trees and vegetation during the Vietnam War. ...

  13. Salicylic acid analogues as chemical exchange saturation transfer MRI contrast agents for the assessment of brain perfusion territory and blood-brain barrier opening after intra-arterial infusion.

    PubMed

    Song, Xiaolei; Walczak, Piotr; He, Xiaowei; Yang, Xing; Pearl, Monica; Bulte, Jeff Wm; Pomper, Martin G; McMahon, Michael T; Janowski, Mirosław

    2016-07-01

    The blood-brain barrier (BBB) is a major obstacle for drug delivery to the brain. Predicted, focal opening of the BBB through intra-arterial infusion of hyperosmolar mannitol is feasible, but there is a need to facilitate imaging techniques (e.g. MRI) to guide interventional procedures and assess the outcomes. Here, we show that salicylic acid analogues (SAA) can depict the brain territory supplied by the catheter and detect the BBB opening, through chemical exchange saturation transfer (CEST) MRI. Hyperosmolar SAA solutions themselves are also capable of opening the BBB, and, when multiple SAA agents were co-injected, their locoregional perfusion could be differentiated. PMID:26980755

  14. Atom Transfer Radical Polymerization of Methacrylic Acid: A Won Challenge.

    PubMed

    Fantin, Marco; Isse, Abdirisak A; Venzo, Alfonso; Gennaro, Armando; Matyjaszewski, Krzysztof

    2016-06-15

    Polymerization of acidic monomers is one of the biggest challenges for atom transfer radical polymerization (ATRP). An intramolecular cyclization reaction leading to the loss of the C-X chain-end functionality was found to be the main reason for the partial termination of the growing polymer chains. Three approaches were used to overcome this problem: using Cl as the chain-end halogen, lowering the pH (to 0.9), and increasing polymerization rate. Methacrylic acid (MAA) was polymerized by both electrochemically mediated ATRP and supplemental activator and reducing agent ATRP up to high conversion (>90%), in t ≤ 4 h at 25 °C, using inexpensive and nontoxic reagents (NaCl, diluted HCl, water). Control over molecular weight (MW) dispersity was satisfactory, and MWs were in agreement with theoretical values. The "livingness" of the process was confirmed by an electrochemical switch, used to repeatedly and periodically deactivate/reactivate growing chains. PMID:27244091

  15. Surface molecular imprinting onto fluorescein-coated magnetic nanoparticlesvia reversible addition fragmentation chain transfer polymerization: A facile three-in-one system for recognition and separation of endocrine disrupting chemicals

    NASA Astrophysics Data System (ADS)

    Li, Ying; Dong, Cunku; Chu, Jia; Qi, Jingyao; Li, Xin

    2011-01-01

    In this study, we present a general protocol for the making of surface-imprinted magnetic fluorescence beads viareversible addition-fragmentation chain transfer polymerization. The resulting composites were characterized by X-ray diffraction analysis, transmission electron microscopy, scanning electron microscopy, fluorescence spectroscopy, Fourier transform infrared spectroscopy, and energy dispersive spectroscopy. The as-synthesized beads exhibited homogeneous polymer films (thickness of about 5.7 nm), spherical shape, high fluorescence intensity and magnetic property (Magnetization (Ms) = 3.67 emu g-1). The hybrids bind the original template 17β-estradiol with an appreciable selectivity over structurally related compounds. In addition, the resulting hybrids performed without obvious deterioration after five repeated cycles. This study therefore demonstrates the potential of molecularly imprinted polymers for the recognition and separation of endocrine disrupting chemicals.In this study, we present a general protocol for the making of surface-imprinted magnetic fluorescence beads viareversible addition-fragmentation chain transfer polymerization. The resulting composites were characterized by X-ray diffraction analysis, transmission electron microscopy, scanning electron microscopy, fluorescence spectroscopy, Fourier transform infrared spectroscopy, and energy dispersive spectroscopy. The as-synthesized beads exhibited homogeneous polymer films (thickness of about 5.7 nm), spherical shape, high fluorescence intensity and magnetic property (Magnetization (Ms) = 3.67 emu g-1). The hybrids bind the original template 17β-estradiol with an appreciable selectivity over structurally related compounds. In addition, the resulting hybrids performed without obvious deterioration after five repeated cycles. This study therefore demonstrates the potential of molecularly imprinted polymers for the recognition and separation of endocrine disrupting chemicals. Electronic

  16. Kinetics and mechanism of electron transfer reaction of single and double chain surfactant cobalt(III) complex by Fe2+ ions in liposome (dipalmitoylphosphotidylcholine) vesicles: effects of phase transition

    NASA Astrophysics Data System (ADS)

    Nagaraj, Karuppiah; Senthil Murugan, Krishnan; Thangamuniyandi, Pilavadi

    2015-05-01

    In this study, we report the kinetics of reduction reactions of single and double chain surfactant cobalt(III) complexes of octahedral geometry, cis-[Co(en)2(4AMP)(DA)](ClO4)3 and cis-[Co(dmp)2(C12H25NH2)2](ClO4)3 (en = ethylenediamine, dmp = 1,3-diaminopropane, 4AMP = 4-aminopropane, C12H25NH2 = dodecylamine) by Fe2+ ion in dipalmitoylphosphotidylcholine (DPPC) vesicles at different temperatures under pseudo first-order conditions. The kinetics of these reactions is followed by spectrophotometry method. The reactions are found to be second order and the electron transfer is postulated as outer sphere. The remarkable findings in the present investigation are that, below the phase transition temperature of DPPC, the rate decreases with an increase in the concentration of DPPC, while above the phase transition temperature the rate increases with an increase in the concentration of DPPC. The main driving force for this phenomenon is considered to be the intervesicular hydrophobic interaction between vesicles surface and hydrophobic part of the surfactant complexes. Besides, comparing the values of rate constants of these outer-sphere electron transfer reactions in the absence and in the presence of DPPC, the rate constant values in the presence of DPPC are always found to be greater than in the absence of DPPC. This is ascribed to the double hydrophobic fatty acid chain in the DPPC that gives the molecule an overall tubular shape due to the intervesicular hydrophobic interaction between vesicles surface and hydrophobic part of the surfactant complexes more suitable for vesicle aggregation which facilitates lower activation energy, and consequently higher rate is observed in the presence of DPPC. The activation parameters (ΔS# and ΔH#) of the reactions at different temperatures have been calculated which corroborate the kinetics of the reaction.

  17. Molecularly imprinted polymer coated solid-phase microextraction fiber prepared by surface reversible addition-fragmentation chain transfer polymerization for monitoring of Sudan dyes in chilli tomato sauce and chilli pepper samples.

    PubMed

    Hu, Xiaogang; Fan, Yanan; Zhang, Yi; Dai, Guimei; Cai, Quanling; Cao, Yujuan; Guo, Changjuan

    2012-06-20

    Surface reversible addition-fragmentation chain transfer (RAFT) polymerization method was firstly applied to the preparation of molecularly imprinted polymer (MIP) coated silicon solid-phase microextraction (SPME) fibers. With Sudan I as template, an ultra-thin MIP coating with about 0.55-μm thickness was obtained with homogeneous structure and controlled composition, due to the controllable radical growing and chain propagation in surface RAFT polymerization. The MIP-coated fibers were found with enhanced selectivity coefficients (3.0-6.5) to Sudan I-IV dyes in contrast with those reported in our previous work. Furthermore, the ultra-thin thickness of MIP coating was helpful to the effective elution of template and fast adsorption/desorption kinetics, so only about 18 min was needed for MIP-coated SPME operation. The detection limits of 21-55 ng L(-1) were achieved for four Sudan dyes, when MIP-coated SPME was coupled with liquid chromatography (LC) and mass spectrometry (MS) detection. The MIP-coated SPME-LC-MS/MS method was tested for the monitoring of ultra trace Sudan dyes in spiked chilli tomato sauce and chilli pepper samples, and high enrichment effect, remarkable matrix peaks-removing capability, and consequent high sensitivities were achieved to four Sudan dyes. PMID:22652263

  18. Development and inter-laboratory transfer of a decaplex polymerase chain reaction assay combined with capillary electrophoresis for the simultaneous detection of ten food allergens.

    PubMed

    Cheng, Fang; Wu, Jiajie; Zhang, Jin; Pan, Aihu; Quan, Sheng; Zhang, Dabing; Kim, HaeYeong; Li, Xiang; Zhou, Shan; Yang, Litao

    2016-05-15

    Food allergies cause health risks to susceptible consumers and regulations on labeling of food allergen contents have been implemented in many countries and regions. To achieve timely and accurate food allergen labeling, the development of fast and effective allergen detection methods is very important. Herein, a decaplex polymerase chain reaction (PCR) assay combined with capillary electrophoresis was developed to detect simultaneously 10 common food allergens from hazelnut, pistachio, oat, sesame, peanut, cashew, barley, wheat, soybean and pecan. The absolute limit of detection (LODa) of this system is between 2 and 20 copies of haploid genome, and the relative LOD (LODr) is as low as 0.005% (w/w) in simulated food mixtures. The developed assay was subsequently applied to 20 commercial food products and verified the allergen ingredients stated on the labels. Furthermore, results using this decaplex PCR assay was successfully replicated in three other laboratories, demonstrating the repeatability and applicability of this assay in routine analysis of the 10 food allergens. PMID:26776037

  19. Characterization of a unique [FeS] cluster in the electron transfer chain of the oxygen tolerant [NiFe] hydrogenase from Aquifex aeolicus

    PubMed Central

    Pandelia, Maria-Eirini; Nitschke, Wolfgang; Infossi, Pascale; Giudici-Orticoni, Marie-Thérèse; Bill, Eckhard; Lubitz, Wolfgang

    2011-01-01

    Iron-sulfur clusters are versatile electron transfer cofactors, ubiquitous in metalloenzymes such as hydrogenases. In the oxygen-tolerant Hydrogenase I from Aquifex aeolicus such electron “wires” form a relay to a diheme cytb, an integral part of a respiration pathway for the reduction of O2 to water. Amino acid sequence comparison with oxygen-sensitive hydrogenases showed conserved binding motifs for three iron-sulfur clusters, the nature and properties of which were unknown so far. Electron paramagnetic resonance spectra exhibited complex signals that disclose interesting features and spin-coupling patterns; by redox titrations three iron-sulfur clusters were identified in their usual redox states, a [3Fe4S] and two [4Fe4S], but also a unique high-potential (HP) state was found. On the basis of 57Fe Mössbauer spectroscopy we attribute this HP form to a superoxidized state of the [4Fe4S] center proximal to the [NiFe] site. The unique environment of this cluster, characterized by a surplus cysteine coordination, is able to tune the redox potentials and make it compliant with the [4Fe4S]3+ state. It is actually the first example of a biological [4Fe4S] center that physiologically switches between 3+, 2+, and 1+ oxidation states within a very small potential range. We suggest that the (1 + /2+) redox couple serves the classical electron transfer reaction, whereas the superoxidation step is associated with a redox switch against oxidative stress. PMID:21444783

  20. Derepression of Synthesis of the Aminoacyl-Transfer Ribonucleic Acid Synthetases for the Branched-Chain Amino Acids of Escherichia coli

    PubMed Central

    McGinnis, Etheleen; Williams, Ann C.; Williams, L. S.

    1974-01-01

    The kinetics of derepression of valyl-, isoleucyl-, and leucyl-transfer ribonucleic acid (tRNA) synthetase formation was examined during valine-, isoleucine-, and leucine-limited growth. When valine was limiting growth, valyl-tRNA synthetase formation was maximally derepressed within 5 min, whereas the rates of synthesis of isoleucyl-, and leucyl-tRNA synthetases were unchanged. Isoleucine-restricted growth caused a maximal derepression of isoleucyl-tRNA synthetase formation in 5 min and derepression of valyl-tRNA synthetase formation in 15 min with no effect on leucyl-tRNA synthetase formation. When leucine was limiting growth, leucyl-tRNA synthetase formation was immediately derepressed, whereas valyl- and isoleucyl-tRNA synthetase formation was unaffected by manipulation of the leucine supply to the cells. These results support our previous findings that valyl-tRNA synthetase formation is subject to multivalent repression control by both isoleucine and valine. In contrast, repression control of iso-leucyl- and leucyl-tRNA synthetase formation is specifically mediated by the supply of the cognate amino acid. PMID:4604302

  1. A marriage of convenience; a simple food chain comprised of Lemna minor (L.) and Gammarus pulex (L.) to study the dietary transfer of zinc.

    PubMed

    Lahive, E; O'Halloran, J; Jansen, M A K

    2015-01-01

    Macrophytes contribute significantly to the cycling of metals in aquatic systems, through accumulation during growth and release during herbivory or decomposition. Accumulation of high levels of metals has been extensively documented in Lemnaceae (duckweeds). However, the degree of trophic transfer of metals from Lemnaceae to secondary consumers remains poorly understood. This study demonstrates that zinc accumulated in Lemna minor is bioavailable to the herbivore consumer Gammarus pulex. Overall, the higher the zinc content of L. minor, the more zinc accumulated in G. pulex. Accumulation in G. pulex was such that mortality occurred when they were fed high zinc-containing L. minor. Yet, the percentage of consumed zinc retained by G. pulex actually decreased with higher zinc concentrations in L. minor. We hypothesise that this decrease reflects internal zinc metabolism, including a shift from soluble to covalently bound zinc in high zinc-containing L. minor. Consistently, relatively more zinc is lost through depuration when G. pulex is fed L. minor with high zinc content. The developed Lemna-Gammarus system is simple, easily manipulated, and sensitive enough for changes in plant zinc metabolism to be reflected in metal accumulation by the herbivore, and therefore suitable to study ecologically relevant metal cycling in aquatic ecosystems. PMID:24731282

  2. Long-term impact of sewage irrigation on soil properties and assessing risk in relation to transfer of metals to human food chain.

    PubMed

    Meena, Ramu; Datta, S P; Golui, Debasis; Dwivedi, B S; Meena, M C

    2016-07-01

    A case study was undertaken to assess the risk of sewage-irrigated soils in relation to the transfer of trace elements to rice and wheat grain. For this purpose, peri-urban agricultural lands under the Keshopur Effluent Irrigation Scheme (KEIS) of Delhi were selected. These agricultural lands have been receiving irrigation through sewage effluents since 1979. Sewage effluent, groundwater, soil, and plant (rice and wheat grain) samples were collected with GPS coordinates from this peri-urban area. Under wheat crop, sewage irrigation for four decades resulted into a significant buildup of zinc (141 %), copper (219 %), iron (514 %), nickel (75.0 %), and lead (28.1 %) in sewage-irrigated soils over adjacent tube well water-irrigated ones. Under rice crop, there was also a significant buildup of phosphorus (339 %), sulfur (130 %), zinc (287 %), copper (352 %), iron (457 %), nickel (258 %), lead (136 %), and cadmium (147 %) in sewage-irrigated soils as compared to that of tube well water-irrigated soils. The values of hazard quotient (HQ) for intake of trace toxic elements by humans through consumption of rice and wheat grain grown on these sewage-irrigated soils were well within the safe permissible limit. The variation in Zn, Ni, and Cd content in wheat grain could be explained by solubility-free ion activity model (FIAM) to the extent of 50.1, 56.8, and 37.2 %, respectively. Corresponding values for rice grain were 49.9, 41.2, and 42.7 %, respectively. As high as 36.4 % variation in As content in rice grain could be explained by solubility-FIAM model. Toxic limit of extractable Cd and As in soil for rice in relation to soil properties and human health hazard associated with consumption of rice grain by humans was established. A similar exercise was also done in respect of Cd for wheat. The conceptual framework of fixing the toxic limit of extractable metals and metalloid in soils with respect to soil properties and human health hazard under the

  3. Biological Agents

    MedlinePlus

    ... to Z Index Contact Us FAQs What's New Biological Agents This page requires that javascript be enabled ... and Health Topics A-Z Index What's New Biological agents include bacteria, viruses, fungi, other microorganisms and ...

  4. Charge-Transfer-Assisted Supramolecular 1 D Nanofibers through a Cholesteric Structure-Directing Agent: Self-Assembly Design for Supramolecular Optoelectronic Materials.

    PubMed

    Babu, Thunga Madhu; Prasad, Edamana

    2015-08-17

    Self-assembly of pyrene butyric acid (PBA) and 2,4,7-trinitro-9H-fluoren-9-one (TNF) directed by a pyridine-linked cholesterol unit resulted in the formation of a conducting material (1.9472×10(-4)  S Cm(-1) ) due to the formation of 1 D nanofibers. X-ray diffraction, IR, and atomic force microscopic (AFM) techniques were used to establish the mechanism of the self-assembly of the multicomponent gels. Results indicate efficient charge transfer in the 1 D nanofibers, assisted by hydrogen bonding. PMID:26189871

  5. Agent amplified communication

    SciTech Connect

    Kautz, H.; Selman, B.; Milewski, A.

    1996-12-31

    We propose an agent-based framework for assisting and simplifying person-to-person communication for information gathering tasks. As an example, we focus on locating experts for any specified topic. In our approach, the informal person-to-person networks that exist within an organization are used to {open_quotes}referral chain{close_quotes} requests for expertise. User-agents help automate this process. The agents generate referrals by analyzing records of e-mail communication patterns. Simulation results show that the higher responsiveness of an agent-based system can be effectively traded for the higher accuracy of a completely manual approach. Furthermore, preliminary experience with a group of users on a prototype system has shown that useful automatic referrals can be found in practice. Our experience with actual users has also shown that privacy concerns are central to the successful deployment of personal agents: an advanced agent-based system will therefore need to reason about issues involving trust and authority.

  6. Preparation of a bifunctional pyrazosulfuron-ethyl imprinted polymer with hydrophilic external layers by reversible addition-fragmentation chain transfer polymerization and its application in the sulfonylurea residue analysis.

    PubMed

    Yang, Meixian; Zhang, Yingying; Lin, Shen; Yang, Xinlin; Fan, Zhijin; Yang, Lixia; Dong, Xiangchao

    2013-09-30

    A new bifunctional pyrazosulfuron-ethyl imprinted polymer was synthesized by the combination of molecular imprinting technology and living radical polymerization. In the synthesis, the pyrazosulfuron-ethyl imprinted polymer was obtained by the reversible addition-fragmentation chain transfer (RAFT) precipitation polymerization followed by grafting poly(glyceryl monomethacrylate) (pGMMA) by the post-RAFT polymerization. In this research, we used polyethylene glycol (PEG) as the polymeric porogen in order to increase the porosity of the material which is a new porogen application in the precipitation polymerization. The imprinted polymer has selectivity for the template and ability of humic acids exclusion which has shown the merits of molecularly imprinted polymers and restricted access materials. An online solid-phase extraction/HPLC method for the analysis of three sulfonylurea residues in soil samples has been developed and validated. The recovery of 81-99% in the spiked levels of 40-200 μg kg(-1) was obtained and the limit of detection (LOD) and limit of quantification (LOQ) were less than 4.8 and 15.9 μg kg(-1) respectively. The results demonstrated that this bifunctional material can be used for the efficient pyrazosulfuron-ethyl extraction in the sulfonylurea residue analysis from environmental samples. PMID:23953454

  7. Detection of Babesia canis vogeli and Hepatozoon canis in canine blood by a single-tube real-time fluorescence resonance energy transfer polymerase chain reaction assay and melting curve analysis.

    PubMed

    Kongklieng, Amornmas; Intapan, Pewpan M; Boonmars, Thidarut; Thanchomnang, Tongjit; Janwan, Penchom; Sanpool, Oranuch; Lulitanond, Viraphong; Taweethavonsawat, Piyanan; Chungpivat, Sudchit; Maleewong, Wanchai

    2015-03-01

    A real-time fluorescence resonance energy transfer polymerase chain reaction (qFRET PCR) coupled with melting curve analysis was developed for detection of Babesia canis vogeli and Hepatozoon canis infections in canine blood samples in a single tube assay. The target of the assay was a region within the 18S ribosomal RNA gene amplified in either species by a single pair of primers. Following amplification from the DNA of infected dog blood, a fluorescence melting curve analysis was done. The 2 species, B. canis vogeli and H. canis, could be detected and differentiated in infected dog blood samples (n = 37) with high sensitivity (100%). The detection limit for B. canis vogeli was 15 copies of a positive control plasmid, and for H. canis, it was 150 copies of a positive control plasmid. The assay could simultaneously distinguish the DNA of both parasites from the DNA of controls. Blood samples from 5 noninfected dogs were negative, indicating high specificity. Several samples can be run at the same time. The assay can reduce misdiagnosis and the time associated with microscopic examination, and is not prone to the carryover contamination associated with the agarose gel electrophoresis step of conventional PCR. In addition, this qFRET PCR method would be useful to accurately determine the range of endemic areas or to discover those areas where the 2 parasites co-circulate. PMID:25776544

  8. Automatic microbial transfer

    NASA Technical Reports Server (NTRS)

    Wilkins, J. R.; Mills, S. M.

    1973-01-01

    Device can transfer metabolites or inhibitory agents to broth cultures of bacteria, in various stages of growth, for study. It also has application in transfer of other micro-organisms, such as yeasts, and could be useful in clinical and research laboratories. Device has been used for wide variety of purposes in experimental situations.

  9. Fluorescence resonance energy transfer-based real-time polymerase chain reaction method without DNA extraction for the genotyping of F5, F2, F12, MTHFR, and HFE.

    PubMed

    Martinez-Serra, Jordi; Robles, Juan; Nicolàs, Antoni; Gutierrez, Antonio; Ros, Teresa; Amat, Juan Carlos; Alemany, Regina; Vögler, Oliver; Abelló, Aina; Noguera, Aina; Besalduch, Joan

    2014-01-01

    Blood samples are extensively used for the molecular diagnosis of many hematological diseases. The daily practice in a clinical laboratory of molecular diagnosis in hematology involves using a variety of techniques, based on the amplification of nucleic acids. Current methods for polymerase chain reaction (PCR) use purified genomic DNA, mostly isolated from total peripheral blood cells or white blood cells (WBC). In this paper we describe a real-time fluorescence resonance energy transfer-based method for genotyping directly from blood cells. Our strategy is based on an initial isolation of the WBCs, allowing the removal of PCR inhibitors, such as the heme group, present in the erythrocytes. Once the erythrocytes have been lysed, in the LightCycler(®) 2.0 Instrument, we perform a real-time PCR followed by a melting curve analysis for different genes (Factors 2, 5, 12, MTHFR, and HFE). After testing 34 samples comparing the real-time crossing point (CP) values between WBC (5×10(6) WBC/mL) and purified DNA (20 ng/μL), the results for F5 Leiden were as follows: CP mean value for WBC was 29.26±0.566 versus purified DNA 24.79±0.56. Thus, when PCR was performed from WBC (5×10(6) WBC/mL) instead of DNA (20 ng/μL), we observed a delay of about 4 cycles. These small differences in CP values were similar for all genes tested and did not significantly affect the subsequent analysis by melting curves. In both cases the fluorescence values were high enough, allowing a robust genotyping of all these genes without a previous DNA purification/extraction. PMID:25028568

  10. Rhodobacter capsulatus DprA is essential for RecA-mediated gene transfer agent (RcGTA) recipient capability regulated by quorum-sensing and the CtrA response regulator.

    PubMed

    Brimacombe, Cedric A; Ding, Hao; Beatty, J Thomas

    2014-06-01

    Gene transfer agents (GTAs) are genetic exchange elements that resemble small DNA bacteriophages that transfer random pieces of the producing cell's genome to recipient cells. The best-studied GTA is that of Rhodobacter capsulatus, termed RcGTA. We discovered that the putative response regulator CtrA, which is essential for RcGTA production, is required for RcGTA-mediated gene acquisition, and confirmed that a RecA homologue is required. It was also discovered that a DprA (DNA-protecting protein A) homologue is essential for RcGTA-mediated gene acquisition, and that dprA expression is induced by gtaI-dependent quorum-sensing and non-phosphorylated CtrA. Modelling of the R. capsulatus DprA structure indicated the presence of a C-terminal region that resembles a dsDNA-binding protein domain. Purified His-tagged R. capsulatus DprA protein bound to both single-stranded (ss)DNA and double-stranded (ds)DNA, but with a greater affinity for ssDNA. Additionally, DprA protected dsDNA from endonuclease digestion, and increased the rate of nucleation of Escherichia coli RecA onto ssDNA. Single-cell expression analyses revealed that dprA is expressed in the majority of cells throughout a population. Overall, the results suggest that incorporation of RcGTA DNA into the recipient cell genome proceeds through a homologous recombination pathway resembling DNA recombination in natural transformation. PMID:24784901

  11. Quantum spin chains with fractional revival

    NASA Astrophysics Data System (ADS)

    Genest, Vincent X.; Vinet, Luc; Zhedanov, Alexei

    2016-08-01

    A systematic study of fractional revival at two sites in XX quantum spin chains is presented. Analytic models with this phenomenon are obtained by combining two basic ways of realizing fractional revival in a spin chain. The first proceeds through isospectral deformations of spin chains with perfect state transfer. The second makes use of couplings provided by the recurrence coefficients of polynomials with a bi-lattice orthogonality grid. The latter method leads to analytic models previously identified that can exhibit perfect state transfer in addition to fractional revival.

  12. Dangling chain elastomers as repeatable fibrillar adhesives.

    PubMed

    Sitti, Metin; Cusick, Brian; Aksak, Burak; Nese, Alper; Lee, Hyung-il; Dong, Hongchen; Kowalewski, Tomasz; Matyjaszewski, Krzysztof

    2009-10-01

    This work reports on repeatable adhesive materials prepared by controlled grafting of dangling hetero chains from polymer elastomers. The dangling chain elastomer system was prepared by grafting poly(n-butyl acrylate) (PBA) chains from prefunctionalized polydimethylsiloxane (PDMS) elastomer networks using atom transfer radical polymerization. To study the effects of chain growth and network strain as they relate to network adhesion mechanics, various lengths of PBA chains with degree of polymerizations (DP) of 65, 281, 508, and 1200 were incorporated into the PDMS matrix. PBA chains with a DP value of 281 grafted from a flat PDMS substrate showed the highest (approximately 3.5-fold) enhancement of nano- and macroscale adhesion relative to a flat raw (ungrafted and not prefunctionalized) PDMS substrate. Moreover, to study the effect of PBA dangling chains on adhesion in fibrillar elastomer structures inspired by gecko foot hairs, a dip-transfer fabrication method was used to graft PBA chains with a DP value of 296 from the tip endings of mushroom-shaped PDMS micropillars. A PBA chain covered micropillar array showed macroscale adhesion enhancement up to approximately 7 times relative to the flat ungrafted prefunctionalized PDMS control substrate, showing additional nonoptimized approximately 2-fold adhesion enhancement due to fibrillar structuring and mushroom-shaped tip ending. These dangling hetero chains on elastomer micro-/nanofibrillar structures may provide a novel fabrication platform for multilength scale, repeatable, and high-strength fibrillar adhesives inspired by gecko foot hairs. PMID:20355863

  13. Sunscreening Agents

    PubMed Central

    Martis, Jacintha; Shobha, V; Sham Shinde, Rutuja; Bangera, Sudhakar; Krishnankutty, Binny; Bellary, Shantala; Varughese, Sunoj; Rao, Prabhakar; Naveen Kumar, B.R.

    2013-01-01

    The increasing incidence of skin cancers and photodamaging effects caused by ultraviolet radiation has increased the use of sunscreening agents, which have shown beneficial effects in reducing the symptoms and reoccurrence of these problems. Many sunscreen compounds are in use, but their safety and efficacy are still in question. Efficacy is measured through indices, such as sun protection factor, persistent pigment darkening protection factor, and COLIPA guidelines. The United States Food and Drug Administration and European Union have incorporated changes in their guidelines to help consumers select products based on their sun protection factor and protection against ultraviolet radiation, whereas the Indian regulatory agency has not yet issued any special guidance on sunscreening agents, as they are classified under cosmetics. In this article, the authors discuss the pharmacological actions of sunscreening agents as well as the available formulations, their benefits, possible health hazards, safety, challenges, and proper application technique. New technologies and scope for the development of sunscreening agents are also discussed as well as the role of the physician in patient education about the use of these agents. PMID:23320122

  14. Crater Chains

    NASA Technical Reports Server (NTRS)

    2003-01-01

    [figure removed for brevity, see original site]

    The large crater at the top of this THEMIS visible image has several other craters inside of it. Most noticeable are the craters that form a 'chain' on the southern wall of the large crater. These craters are a wonderful example of secondary impacts. They were formed when large blocks of ejecta from an impact crashed back down onto the surface of Mars. Secondaries often form radial patterns around the impact crater that generated them, allowing researchers to trace them back to their origin.

    Note: this THEMIS visual image has not been radiometrically nor geometrically calibrated for this preliminary release. An empirical correction has been performed to remove instrumental effects. A linear shift has been applied in the cross-track and down-track direction to approximate spacecraft and planetary motion. Fully calibrated and geometrically projected images will be released through the Planetary Data System in accordance with Project policies at a later time.

    NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA's Office of Space Science, Washington, D.C. The Thermal Emission Imaging System (THEMIS) was developed by Arizona State University, Tempe, in collaboration with Raytheon Santa Barbara Remote Sensing. The THEMIS investigation is led by Dr. Philip Christensen at Arizona State University. Lockheed Martin Astronautics, Denver, is the prime contractor for the Odyssey project, and developed and built the orbiter. Mission operations are conducted jointly from Lockheed Martin and from JPL, a division of the California Institute of Technology in Pasadena.

    Image information: VIS instrument. Latitude 19.3, Longitude 347.5 East (12.5 West). 19 meter/pixel resolution.

  15. Entropy-Driven Selectivity for Chain Scission: Where Macromolecules Cleave.

    PubMed

    Pahnke, Kai; Brandt, Josef; Gryn'ova, Ganna; Lin, Ching Y; Altintas, Ozcan; Schmidt, Friedrich G; Lederer, Albena; Coote, Michelle L; Barner-Kowollik, Christopher

    2016-01-22

    We show that, all other conditions being equal, bond cleavage in the middle of molecules is entropically much more favored than bond cleavage at the end. Multiple experimental and theoretical approaches have been used to study the selectivity for bond cleavage or dissociation in the middle versus the end of both covalent and supramolecular adducts and the extensive implications for other fields of chemistry including, e.g., chain transfer, polymer degradation, and control agent addition are discussed. The observed effects, which are a consequence of the underlying entropic factors, were predicted on the basis of simple theoretical models and demonstrated via high-temperature (HT) NMR spectroscopy of self-assembled supramolecular diblock systems as well as temperature-dependent size-exclusion chromatography (TD SEC) of covalently bonded Diels-Alder step-growth polymers. PMID:26663567

  16. An Organizational Knowledge Ontology for Automotive Supply Chains

    NASA Astrophysics Data System (ADS)

    Hellingrath, Bernd; Witthaut, Markus; Böhle, Carsten; Brügger, Stephan

    The currently completed ILIPT (Intelligent Logistics for Innovative Product Technologies) project was concerned with the concept of the “5 day car” (a customized car that is delivered within five days after its ordering) and encompassed extensive research on the required production and logistics network structures and processes. As car manufacturers in the automotive industry (commonly referred to as OEMs) rely heavily on their suppliers, the major challenge lies in the organization of inter-enterprise cooperation supported by information systems (IS) in an efficient manner. A common understanding of supply chain concepts is indispensable for this. Ontologies as formal representations of concepts can be used as a semantic basis for cooperation. Relevant results from ILIPT are presented followed by a concept as well as a prototype of how to transfer the theoretical findings to a practical implementation, in this case a multi-agent system.

  17. Photoinduced electron transfer in ordered polymers

    SciTech Connect

    Jones, G. II.

    1991-12-01

    Long range photoinduced electron transfer between electron donor and acceptor groups is of considerable current interest in terms of strategies for artificial photosynthesis and studies regarding the redox properties of proteins. As part of an extensive study of long range electron transfer involving biopolymers, we have carried out this year investigations of the assembly of electron transfer agents in a system of model short peptides. Also studied is a polyelectrolyte that can adopt a helical conformation when electrostatically complexed with organic dye counter-ions. The principal interest in these systems has to do with the well ordered secondary structures adopted by peptide polymers, and the capabilities for synthetic modification of peptide side chains and end groups with chromophores or electroactive substituents. The present report gives a brief account of the following elements of work related to photochemical electron transfer themes: (1) the synthesis and photochemical characterization of chromophore-bound peptides and amino acid model compounds based on the amino acids, tryptophan and the spacer residue, alanine (Ala); (2) the study of binding of the cationic organic dye to a peptide electrolyte, for which cooperative dye loading and helix formation is important; and (3) completion of the synthesis of a new series of acridinium chromophores that have rod-like'' arrangements of inked aryl rings for assembly of electron donor-acceptor systems that will exhibit especially long lived charge separation.

  18. Precise Nanoelectronics with Adatom Chains

    NASA Technical Reports Server (NTRS)

    Yamada, Toshishige

    1999-01-01

    Adatom chains on an atomically regulated substrate will be building components in future precise nanoelectronics. Adatoms need to be secured with chemical bonding, but then electronic isolation between the adatom and substrate systems is not guaranteed. A one-dimensional model shows that good isolation with existence of surface states is expected on an s-p crossing substrate such as Si, Ge, or GaAs, reflecting the bulk nature of the substrate. Isolation is better if adatoms are electronically similar to the substrate atoms, and can be manipulated by hydrogenation. Chain structures with group IV adatoms with two chemical bonds, or group III adatoms with one chemical bond, are semiconducting, reflecting the surface nature of the substrate. These structures are unintentionally doped due to the charge transfer across the chemical bonds. Physical properties of adatom chains have to be determined for the unified adatom-substrate system.

  19. Chain reconfiguration in active noise

    NASA Astrophysics Data System (ADS)

    Samanta, Nairhita; Chakrabarti, Rajarshi

    2016-05-01

    In a typical single molecule experiment, the dynamics of an unfolded protein is studied by determining the reconfiguration time using long-range Förster resonance energy transfer, where the reconfiguration time is the characteristic decay time of the position correlation between two residues of the protein. In this paper we theoretically calculate the reconfiguration time for a single flexible polymer in the presence of active noise. The study suggests that though the mean square displacement grows faster, the chain reconfiguration is always slower in the presence of long-lived active noise with exponential temporal correlation. Similar behavior is observed for a worm-like semi-flexible chain and a Zimm chain. However it is primarily the characteristic correlation time of the active noise and not the strength that controls the increase in the reconfiguration time. In brief, such active noise makes the polymer move faster but the correlation loss between the monomers becomes slow.

  20. Antidiabetic Agents.

    ERIC Educational Resources Information Center

    Plummer, Nancy; Michael, Nancy, Ed.

    This module on antidiabetic agents is intended for use in inservice or continuing education programs for persons who administer medications in long-term care facilities. Instructor information, including teaching suggestions, and a listing of recommended audiovisual materials and their sources appear first. The module goal and objectives are then…

  1. Design, synthesis and in vitro biological evaluation of short-chain C12-sphinganine and its 1,2,3-triazole analogs as potential antimicrobial and anti-biofilm agents.

    PubMed

    Vijai Kumar Reddy, T; Jyotsna, A; Prabhavathi Devi, B L A; Prasad, R B N; Poornachandra, Y; Ganesh Kumar, C

    2016-08-01

    A conceptual synthetic approach of short-chain C12-sphinganine 1 and a small library of its 1,2,3-triazole analogs 2(a-f) has been accomplished using the commercially available and inexpensive 10-undecenoic acid as a starting material. Miyashita's C-2 selective endo mode azidolysis and Huisgen click reaction was employed for the synthesis of the designed analogs. Based on biological evaluation studies of all the synthesized compounds, it was observed that, (2S,3R)-2-(4-(3-hydroxyphenyl)-1H-1,2,3-triazol-1-yl)dodecan-1,3-diol (2b) exhibited promising antimicrobial and antifungal activities. Furthermore, compound 2b was able to inhibit the biofilm formation of Candida albicans MTCC 227, Micrococcus luteus MTCC 2470 and Staphylococcus aureus MTCC 96 with IC50 values of 1.9, 2.1 and 2.9 μg/mL, respectively. Compound 2b increased the levels of reactive oxygen species (ROS) in C. albicans MTCC 227. PMID:27128176

  2. Antiparasitic agents.

    PubMed

    Rosenblatt, J E

    1999-11-01

    Several important developments have occurred in recent years in the chemotherapy for and prophylaxis of parasitic infections. Although mefloquine is clearly the most effective agent for prevention of chloroquine-resistant falciparum malaria, its use has been compromised by side effects, both real and imagined. Well-designed studies have shown that side effects occur no more frequently with low-dose mefloquine than with chloroquine. Use of mefloquine in pregnant women has not been associated with birth defects, but the incidence of stillbirths may be increased. Malarone is a new agent that combines atovaquone and proguanil, and it may be as effective as mefloquine; however, it is not yet available in the United States. Several newer agents have appeared in response to the development of multidrug resistant Plasmodium falciparum, especially in Southeast Asia. Halofantrine is available for the treatment of mild to moderate malaria due to P. falciparum and for P. vivax infections. Because of severe toxic effects, use of halofantrine should be restricted to only those unusual and rare situations in which other agents cannot be used. Artemisinin (an extract of the Chinese herbal remedy qinghaosu) and two derivatives, artesunate and artemether, are active against multidrug resistant P. falciparum and are widely used in Asia in oral, parenteral, and rectal forms. The antibacterial azithromycin in combination with atovaquone or quinine has now been reported to treat babesiosis effectively in experimental animals and in a few patients. Azithromycin in combination with paromomycin has also shown promise in the treatment of cryptosporidiosis (and toxoplasmosis when combined with pyrimethamine) in patients with the acquired immunodeficiency syndrome (AIDS). Albendazole is currently the only systemic agent available for treatment of microsporidiosis, an infection primarily of patients with AIDS. In addition, albendazole and ivermectin have emerged as effective broad

  3. The human element in technology transfer

    NASA Technical Reports Server (NTRS)

    Peake, H. J.

    1978-01-01

    A transfer model composed of three roles and their linkages was considered. This model and a growing body of experience was analyzed to provide guidance in the human elements of technology transfer. For example, criteria for selection of technology transfer agents was described, and some needed working climate factors were known. These concepts were successfully applied to transfer activities.

  4. Health supply chain management.

    PubMed

    Zimmerman, Rolf; Gallagher, Pat

    2010-01-01

    This chapter gives an educational overview of: * The actual application of supply chain practice and disciplines required for service delivery improvement within the current health environment. * A rationale for the application of Supply Chain Management (SCM) approaches to the Health sector. * The tools and methods available for supply chain analysis and benchmarking. * Key supply chain success factors. PMID:20407173

  5. Antifungal agents.

    PubMed

    Ryder, N S

    1999-12-01

    At this year's ICAAC Meeting, new data on approximately 20 different antifungal agents were presented, while no new agents were disclosed. Drugs in late development include the triazoles, voriconazole (Pfizer Ltd) and Sch-56592 (Schering-Plough Corp), and the echinocandins, caspofungin (Merck & Co Inc) and FK-463 (Fujisawa Pharmaceutical Co Ltd). In contrast to previous years, presentations on these and earlier developmental compounds were relatively modest in scope, with few significant new data. Little new information appeared on the most recent novel class of agents, the sordarins (Glaxo Wellcome plc). Early clinical results were presented for FK-463, showing acceptable tolerability and dose-dependent efficacy in AIDS-associated esophageal candidiasis. A new liposomal formulation of nystatin (Nyotran; Aronex Pharmaceuticals Inc) was shown to be equivalent to conventional amphotericin B in empiric therapy of presumed fungal infection in neutropenic patients, but with reduced toxicity. Intravenous itraconazole (Janssen Pharmaceutica NV) was an effective prophylactic therapy in invasive pulmonary aspergillosis, while oral itraconazole was discussed as a treatment for fungal infection in heart and liver transplant patients. The allylamine compound, terbinafine (Novartis AG), showed good clinical efficacy against fungal mycetoma, a serious tropical infection. A major highlight was the first presentation of inhibitors of fungal efflux pumps as a strategy for overcoming resistance. MC-510027 (milbemycin alpha-9; Microcide Pharmaceuticals Inc) and its derivatives, potentiated the antifungal activity of triazoles and terbinafine in a number of Candida spp. Another pump inhibitor, MC-005172 (Microcide Pharmaceuticals Inc) showed in vivo potentiation of fluconazole in a mouse kidney infection model. Microcide Pharmaceuticals Inc also presented inhibitors of bacterial efflux pumps. PMID:16113946

  6. KGB agents

    NASA Astrophysics Data System (ADS)

    Gaina, Alex

    A short story is reported in which the activity of Communist Party of the USSR and secret KGB agents, which were payed by the State, in view of controlling of the conscience of population. The story reffers to the Physics Department of the Moscow University, Planing Institute of the Gosplan of Moldavian S.S.R. and Chishinau Technical University (actually: Technical University of Moldova), where the author has worked during Soviet times. Almost every 6-th citizen in the USSR was engaged in this activity, while actually the former communists rule in the Republic of Moldova.

  7. [New agents for hypercholesterolemia].

    PubMed

    Pintó, Xavier; García Gómez, María Carmen

    2016-02-19

    An elevated proportion of high cardiovascular risk patients do not achieve the therapeutic c-LDL goals. This owes to physicians' inappropriate or insufficient use of cholesterol lowering medications or to patients' bad tolerance or therapeutic compliance. Another cause is an insufficient efficacy of current cholesterol lowering drugs including statins and ezetimibe. In addition, proprotein convertase subtilisin kexin type 9 inhibitors are a new cholesterol lowering medications showing safety and high efficacy to reduce c-LDL in numerous already performed or underway clinical trials, potentially allowing an optimal control of hypercholesterolemia in most patients. Agents inhibiting apolipoprotein B synthesis and microsomal transfer protein are also providing a new potential to decrease cholesterol in patients with severe hypercholesterolemia and in particular in homozygote familial hypercholesterolemia. Last, cholesteryl ester transfer protein inhibitors have shown powerful effects on c-HDL and c-LDL, although their efficacy in cardiovascular prevention and safety has not been demonstrated yet. We provide in this article an overview of the main characteristics of therapeutic agents for hypercholesterolemia, which have been recently approved or in an advanced research stage. PMID:25817449

  8. Method of encapsulating polyaminopolycarboxylic acid chelating agents in liposomes

    DOEpatents

    Rahman, Yueh Erh

    1977-11-10

    A method is provided for transferring a polyaminopolycarboxylic acid chelating agent across a cellular membrane by encapsulating the charged chelating agent within liposomes, which liposomes will be taken up by the cells, thereby transferring the chelating agent across the cellular membrane. The chelating agent is encapsulated within liposomes by drying a lipid mixture to form a thin film and wetting the lipid film with a solution containing the chelating agent. Mixing then results in the formation of a suspension of liposomes encapsulating the chelating agent, which liposomes can then be separated.

  9. Conjugative transfer of preferential utilization of aromatic compounds from Pseudomonas putida CSV86.

    PubMed

    Basu, Aditya; Phale, Prashant S

    2008-02-01

    Pseudomonas putida CSV86 utilizes naphthalene (Nap), salicylate (Sal), benzyl alcohol (Balc), and methylnaphthalene (MN) preferentially over glucose. Methylnaphthalene is metabolized by ring-hydroxylation as well as side-chain hydroxylation pathway. Although the degradation property was found to be stable, the frequency of obtaining Nap(-)Sal(-)MN(-)Balc(-) phenotype increased to 11% in the presence of curing agents. This property was transferred by conjugation to Stenotrophomonas maltophilia CSV89 with a frequency of 7 x 10(-8) per donor cells. Transconjugants were Nap(+)Sal(+)MN(+)Balc(+) and metabolized MN by ring- as well as side-chain hydroxylation pathway. Transconjugants also showed the preferential utilization of aromatic compounds over glucose indicating transfer of the preferential degradation property. The transferred properties were lost completely when transconjugants were grown on glucose or 2YT. Attempts to detect and isolate plasmid DNA from CSV86 and transconjugants were unsuccessful. Transfer of degradation genes and its subsequent loss from the transconjugants was confirmed by PCR using primers specific for 1,2-dihydroxynaphthalene dioxygenase and catechol 2,3-dioxygenase (C23O) as well as by DNA-DNA hybridizations using total DNA as template and C23O PCR fragment as a probe. These results indicate the involvement of a probable conjugative element in the: (i) metabolism of aromatic compounds, (ii) ring- and side-chain hydroxylation pathways for MN, and (iii) preferential utilization of aromatics over glucose. PMID:17487554

  10. Plasmids encoding therapeutic agents

    DOEpatents

    Keener, William K.

    2007-08-07

    Plasmids encoding anti-HIV and anti-anthrax therapeutic agents are disclosed. Plasmid pWKK-500 encodes a fusion protein containing DP178 as a targeting moiety, the ricin A chain, an HIV protease cleavable linker, and a truncated ricin B chain. N-terminal extensions of the fusion protein include the maltose binding protein and a Factor Xa protease site. C-terminal extensions include a hydrophobic linker, an L domain motif peptide, a KDEL ER retention signal, another Factor Xa protease site, an out-of-frame buforin II coding sequence, the lacZ.alpha. peptide, and a polyhistidine tag. More than twenty derivatives of plasmid pWKK-500 are described. Plasmids pWKK-700 and pWKK-800 are similar to pWKK-500 wherein the DP178-encoding sequence is substituted by RANTES- and SDF-1-encoding sequences, respectively. Plasmid pWKK-900 is similar to pWKK-500 wherein the HIV protease cleavable linker is substituted by a lethal factor (LF) peptide-cleavable linker.

  11. Laser amplifier chain

    DOEpatents

    Hackel, R.P.

    1992-10-20

    A laser amplifier chain has a plurality of laser amplifiers arranged in a chain to sequentially amplify a low-power signal beam to produce a significantly higher-power output beam. Overall efficiency of such a chain is improved if high-gain, low efficiency amplifiers are placed on the upstream side of the chain where only a very small fraction of the total pumped power is received by the chain and low-gain, high-efficiency amplifiers are placed on the downstream side where a majority of pumping energy is received by the chain. 6 figs.

  12. Laser amplifier chain

    DOEpatents

    Hackel, Richard P.

    1992-01-01

    A laser amplifier chain has a plurality of laser amplifiers arranged in a chain to sequentially amplify a low-power signal beam to produce a significantly higher-power output beam. Overall efficiency of such a chain is improved if high-gain, low efficiency amplifiers are placed on the upstream side of the chain where only a very small fraction of the total pumped power is received by the chain and low-gain, high-efficiency amplifiers are placed on the downstream side where a majority of pumping energy is received by the chain.

  13. 42 CFR 73.16 - Transfers.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 42 Public Health 1 2010-10-01 2010-10-01 false Transfers. 73.16 Section 73.16 Public Health PUBLIC HEALTH SERVICE, DEPARTMENT OF HEALTH AND HUMAN SERVICES QUARANTINE, INSPECTION, LICENSING SELECT AGENTS... select agent or toxin may only be transferred to individuals or entities registered to possess, use,...

  14. Isomerization of alkanes on sulfated zirconia: Promotion by Pt and by adamantyl hydride transfer species

    SciTech Connect

    Iglesia, E.; Soled, S.L.; Kramer, G.M. )

    1993-11-01

    The work shows that hydride transfer species, such as adamantane, increase isomerization rates and inhibit C-C scission reactions. n-Heptane isomerization rates show positive hydrogen kinetic orders, suggesting that the reaction proceeds on Pt/ZrO[sub 2]-SO[sub 4] via chain transfer pathways, in which carbenium ions propagate, after a chain initiation step involvings loss of hydrogen from alkanes, by hydride transfer from neutral species to carbonations. These pathways contrast with those involved in the bifunctional (metal-acid) catalytic sequences usually required for alkane isomerization, in which metal sites catalyze alkane dehydrogenation and acid sites catalyze skeletal rearrangements of alkenes. Rate-limiting hydride transfer steps are consistent with the strong influence of molecular hydride transfer agents such as adamantane, which act as co-catalysts and increase isomerization rate and selectivity. The addition of small amounts of adamantane (0.1-0.8 wt%) to n-heptane increases isomerizations rates by a factor of 3 and inhibits undesirable cracking reactions. Adamantane increases hydride transfer and carbenium ion termination rates, thus reducing the surface residence time required for a catalytic turnover. As a result, desorption occurs before secondary cracking of isomerized carbenium ions. Less effective hydride transfer agents (n-alkanes, isoalkanes) also increase n-alkanes isomerization rate and selectivity, but require much higher concentrations than adamantane. Dihydrogen also acts as a hydride source in alkane isomerization catalysis, but it requires the additional presence of metals or reducible oxides, which catalyze H[sub 2] dissociation and the formation of hydridic and protonic forms of hydrogen. 40 refs., 10 figs., 4 tabs.

  15. Health care agents

    MedlinePlus

    Durable power of attorney for health care; Health care proxy; End-of-life - health care agent; Life support treatment - ... Respirator - health care agent; Ventilator - health care agent; Power of attorney - health care agent; POA - health care ...

  16. Agent Building Software

    NASA Technical Reports Server (NTRS)

    2000-01-01

    AgentBuilder is a software component developed under an SBIR contract between Reticular Systems, Inc., and Goddard Space Flight Center. AgentBuilder allows software developers without experience in intelligent agent technologies to easily build software applications using intelligent agents. Agents are components of software that will perform tasks automatically, with no intervention or command from a user. AgentBuilder reduces the time and cost of developing agent systems and provides a simple mechanism for implementing high-performance agent systems.

  17. Silver nanoparticles well-dispersed in amine-functionalized, one-pot made vesicles as an effective antibacterial agent.

    PubMed

    Deng, Yuanming; Li, Jiefeng; Yu, Junyan; Zhao, Jinlai; Tang, Jiaoning

    2016-03-01

    We report a simple route to prepare silver nanoparticle (Ag NP) loaded amine functionalized poly-oligomeric (ethylene glycol) methyl ether methacrylate block poly-glycidyl methacrylate (POEGMA-b-PGMA) vesicles as an effective antibacterial agent. Self-assemblies of POEGMA-b-PGMA were prepared from reversible addition-fragmentation chain transfer (RAFT) dispersion polymerization mediated by a POEGMA macro-chain transfer agent (macro-CTA) in ethanol. Amine-functionalized self-assemblies were applied for Ag NP loading by using amine and hydroxyl groups as both the coordination agent and reductant under hydrothermal condition in high-pressure steam sterilization. 12.7 wt.% content of fine Ag NP well-dispersed in vesicles showed excellent antibacterial activities with the minimum inhibitory concentration (MIC) and the minimum bactericidal concentration (MBC) below 5.0 and 10.0 mg/L against Escherichia coli and 2.5 and 80 mg/L against Staphylococcus aureus respectively. PMID:26706511

  18. Relations in Chains

    ERIC Educational Resources Information Center

    Mineur, B. W.

    1973-01-01

    The criticisms made against chain indexing are reviewed, and PRECIS briefly considered as a possible (but improbable) general substitute for indexing. The failures of chain indexing arise mainly from an overemphasis on generic relationships. The use of symbols to represent relations between terms is suggested for the chain index. (80 references)…

  19. Advances in Magnetic Resonance Imaging Contrast Agents for Biomarker Detection

    PubMed Central

    Sinharay, Sanhita; Pagel, Mark D.

    2016-01-01

    Recent advances in magnetic resonance imaging (MRI) contrast agents have provided new capabilities for biomarker detection through molecular imaging. MRI contrast agents based on the T2 exchange mechanism have more recently expanded the armamentarium of agents for molecular imaging. Compared with T1 and T2* agents, T2 exchange agents have a slower chemical exchange rate, which improves the ability to design these MRI contrast agents with greater specificity for detecting the intended biomarker. MRI contrast agents that are detected through chemical exchange saturation transfer (CEST) have even slower chemical exchange rates. Another emerging class of MRI contrast agents uses hyperpolarized 13C to detect the agent with outstanding sensitivity. These hyperpolarized 13C agents can be used to track metabolism and monitor characteristics of the tissue microenvironment. Together, these various MRI contrast agents provide excellent opportunities to develop molecular imaging for biomarker detection. PMID:27049630

  20. Advances in Magnetic Resonance Imaging Contrast Agents for Biomarker Detection.

    PubMed

    Sinharay, Sanhita; Pagel, Mark D

    2016-06-12

    Recent advances in magnetic resonance imaging (MRI) contrast agents have provided new capabilities for biomarker detection through molecular imaging. MRI contrast agents based on the T2 exchange mechanism have more recently expanded the armamentarium of agents for molecular imaging. Compared with T1 and T2* agents, T2 exchange agents have a slower chemical exchange rate, which improves the ability to design these MRI contrast agents with greater specificity for detecting the intended biomarker. MRI contrast agents that are detected through chemical exchange saturation transfer (CEST) have even slower chemical exchange rates. Another emerging class of MRI contrast agents uses hyperpolarized (13)C to detect the agent with outstanding sensitivity. These hyperpolarized (13)C agents can be used to track metabolism and monitor characteristics of the tissue microenvironment. Together, these various MRI contrast agents provide excellent opportunities to develop molecular imaging for biomarker detection. PMID:27049630

  1. Advances in Magnetic Resonance Imaging Contrast Agents for Biomarker Detection

    NASA Astrophysics Data System (ADS)

    Sinharay, Sanhita; Pagel, Mark D.

    2016-06-01

    Recent advances in magnetic resonance imaging (MRI) contrast agents have provided new capabilities for biomarker detection through molecular imaging. MRI contrast agents based on the T2 exchange mechanism have more recently expanded the armamentarium of agents for molecular imaging. Compared with T1 and T2* agents, T2 exchange agents have a slower chemical exchange rate, which improves the ability to design these MRI contrast agents with greater specificity for detecting the intended biomarker. MRI contrast agents that are detected through chemical exchange saturation transfer (CEST) have even slower chemical exchange rates. Another emerging class of MRI contrast agents uses hyperpolarized 13C to detect the agent with outstanding sensitivity. These hyperpolarized 13C agents can be used to track metabolism and monitor characteristics of the tissue microenvironment. Together, these various MRI contrast agents provide excellent opportunities to develop molecular imaging for biomarker detection.

  2. Gushing metal chain

    NASA Astrophysics Data System (ADS)

    Belyaev, Alexander; Sukhanov, Alexander; Tsvetkov, Alexander

    2016-03-01

    This article addresses the problem in which a chain falls from a glass from some height. This phenomenon demonstrates a paradoxical rise of the chain over the glass. To explain this effect, an initial hypothesis and an appropriate theory are proposed for calculating the steady fall parameters of the chain. For this purpose, the modified Cayley's problem of falling chain given its rise due to the centrifugal force of upward inertia is solved. Results show that the lift caused by an increase in linear density at the part of chain where it is being bent (the upper part) is due to the convergence of the chain balls to one another. The experiments confirm the obtained estimates of the lifting chain.

  3. 17 CFR 240.17Ad-14 - Tender agents.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 17 Commodity and Securities Exchanges 3 2013-04-01 2013-04-01 false Tender agents. 240.17Ad-14... Exchange Act of 1934 Supervised Investment Bank Holding Company Rules § 240.17Ad-14 Tender agents. (a... the time a tender or exchange offer is commenced, no registered transfer agent shall act on behalf...

  4. 17 CFR 240.17Ad-14 - Tender agents.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 17 Commodity and Securities Exchanges 4 2014-04-01 2014-04-01 false Tender agents. 240.17Ad-14... Exchange Act of 1934 Nationally Recognized Statistical Rating Organizations § 240.17Ad-14 Tender agents. (a... the time a tender or exchange offer is commenced, no registered transfer agent shall act on behalf...

  5. 17 CFR 240.17Ad-14 - Tender agents.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 17 Commodity and Securities Exchanges 3 2012-04-01 2012-04-01 false Tender agents. 240.17Ad-14... Exchange Act of 1934 Supervised Investment Bank Holding Company Rules § 240.17Ad-14 Tender agents. (a... the time a tender or exchange offer is commenced, no registered transfer agent shall act on behalf...

  6. 17 CFR 240.17Ad-14 - Tender agents.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 17 Commodity and Securities Exchanges 3 2011-04-01 2011-04-01 false Tender agents. 240.17Ad-14... Exchange Act of 1934 Supervised Investment Bank Holding Company Rules § 240.17Ad-14 Tender agents. (a... the time a tender or exchange offer is commenced, no registered transfer agent shall act on behalf...

  7. 17 CFR 240.17Ad-14 - Tender agents.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 17 Commodity and Securities Exchanges 3 2010-04-01 2010-04-01 false Tender agents. 240.17Ad-14... Exchange Act of 1934 Supervised Investment Bank Holding Company Rules § 240.17Ad-14 Tender agents. (a... the time a tender or exchange offer is commenced, no registered transfer agent shall act on behalf...

  8. An analytic spin chain model with fractional revival

    NASA Astrophysics Data System (ADS)

    Lemay, Jean-Michel; Vinet, Luc; Zhedanov, Alexei

    2016-08-01

    New analytic spin chains with fractional revival are introduced. Their nearest-neighbor couplings and local magnetic fields correspond to the recurrence coefficients of para-Racah polynomials which are orthogonal on quadratic bi-lattices. These models generalize the spin chain associated to the dual-Hahn polynomials. Instances where perfect state transfer also occurs are identified.

  9. Crater chains on Mercury

    NASA Astrophysics Data System (ADS)

    Shevchenko, V.; Skobeleva, T.

    After discovery of disruption comet Shoemaker-Levy 9 into fragment train before it's collision with Jupiter there was proposed that linear crater chains on the large satellites of Jupiter and on the Moon are impact scars of past tidally disrupted comets.It's known that radar images have revealed the possible presence of water ice deposits in polar regions of Mercury. Impacts by a few large comets seem to provide the best explanation for both the amount and cleanliness of the ice deposits on Mercury because they have a larger volatile content that others external sources, for example, asteroid. A number of crater chains on the surface of Mercury are most likely the impact tracks of "fragment trains" of comets tidally disrupted by Sun or by Mercury and are not secondary craters. Mariner 10 image set (the three Mariner 10 flybys in 1974-1975) was used to recognize the crater chains these did not associate with secondary crater ejecta from observed impact structures. As example, it can be shown such crater chain located near crater Imhotep and crater Ibsen (The Kuiper Quadrangle of Mercury). Resolution of the Mariner 10 image is about 0.54 km/pixel. The crater chain is about 50 km long. It was found a similar crater chain inside large crater Sophocles (The Tolstoj Quadrangle of Mercury). The image resolution is about 1.46 km/pixel. The chain about 50 km long is located in northen part of the crater. Image resolution limits possibility to examine the form of craters strongly. It seems the craters in chains have roughly flat floor and smooth form. Most chain craters are approximately circular. It was examined many images from the Mariner 10 set and there were identified a total 15 crater chains and were unable to link any of these directly to any specific large crater associated with ejecta deposits. Chain craters are remarkably aligned. All distinguished crater chains are superposed on preexisting formations. A total of 127 craters were identified in the 15 recognized

  10. Proton-Coupled Electron-Transfer Mechanism for the Radical Scavenging Activity of Cardiovascular Drug Dipyridamole

    PubMed Central

    Barzegar, Abolfazl

    2012-01-01

    Dipyridamole (DIP) is a well-known pharmaceutical drug used as a coronary vasodilator and anti-platelet agent in clinics for treating several cardiovascular diseases. Primarily, the therapeutic effects of the drug are attributed to its antioxidant potency. In this research, we aim to declare the unknown antioxidant mechanism of DIP as well as its potent chain-breaking antioxidant activity in polar aqueous medium inside the cells, using different experimental methods and theoretical quantum calculations. Data demonstrated the higher antioxidant capacity of DIP against ROS and free radicals in polar cell's interior. DIP is capable of generating long living and noninvasive DIP• radicals in oxidant condition that leads to an effective “chain-breaking antioxidant” activity. Quantum computational data indicated that DIP antioxidant has more favorable ionization potential than trolox which means DIP has higher antioxidant activity. Also, data showed that the direct hydrogen-transfer is not a favorable process to construct DIP• because of high barrier energy, though electron-transfer process can more easily to produce DIP•+ with the lowest barrier energy. Altogether, the electron donating potency of DIP to reduce ferric ion, having the low anodic oxidation peak potential, producing long lived stable DIP• radicals and protecting myoblast cells from oxidation, proposed the excellent “chain-breaking antioxidant” potency via electron-transfer mechanism of this vasodilator DIP drug in polar aqueous medium. PMID:22745807

  11. Preparing Change Agents for Change Agent Roles.

    ERIC Educational Resources Information Center

    Sedlacek, James R.

    Seventy-seven Spanish- and Portuguese-speaking agricultural change agents from developing Central and South American countries responded to a questionnaire which sought perceptions of the roles in which the change agents felt they were involved and the roles for which they felt they were being trained. The agents were participating in training…

  12. Accumulation and transfer of Hg, As, Se, and other metals in the sediment-vegetation-crab-human food chain in the coastal zone of the northern Brazilian state of Pará (Amazonia).

    PubMed

    Vilhena, Maria S P; Costa, Marcondes L; Berredo, Jose Francisco

    2013-08-01

    The high consumption of crabs (Ucides cordatus) stimulated interest in the present study on the northern coast of Brazil, which encompasses a preserved area of mangrove forest. The objective was to describe and quantify the transfer of metals from the muddy sediments to the leaves of the Rhizophora mangle, and thence the crabs and humans. The samples were collected along two transects, while samples of hair were obtained from local habitants. The pH, interstitial salinity, Eh (mV) were measured, the granulometry and mineralogical and multi-element chemical analyses were run, and the organic material determined. The sediments are silty-clayey, composed of quartz, kaolinite, iron oxides, and illite, as well as smaller portions of smectite, pyrite, halite, and high levels of SiO2 (56.5 %), Al2O3 (18.5 %), and Fe2O3 (7 %). The elements Zn, Sr, As, and Zr are concentrated in the leaves, while the bioaccumulation of Zn, Se, Sr, and As was recorded in the crabs, of which, Se is the most concentrated in the tissue of the muscles and the hepatopancreas. The concentrations of nutrient and toxic elements were similar in all age groups (hair samples), with only Hg presenting an increasing concentration between infants and adults. The highest rates of transfer were recorded for the elements Zn and Se in the crabs and Hg in leaves and hair. The accumulation of metals in the leaves and crabs reflects the chemical composition of the sediments and low rates of sediment-vegetation-crab transfer, with the exception of Hg, which accumulated in the hair. PMID:23334486

  13. Tutorial on agent-based modeling and simulation. Part 2 : how to model with agents.

    SciTech Connect

    Macal, C. M.; North, M. J.; Decision and Information Sciences

    2006-01-01

    Agent-based modeling and simulation (ABMS) is a new approach to modeling systems comprised of interacting autonomous agents. ABMS promises to have far-reaching effects on the way that businesses use computers to support decision-making and researchers use electronic laboratories to do research. Some have gone so far as to contend that ABMS is a new way of doing science. Computational advances make possible a growing number of agent-based applications across many fields. Applications range from modeling agent behavior in the stock market and supply chains, to predicting the spread of epidemics and the threat of bio-warfare, from modeling the growth and decline of ancient civilizations to modeling the complexities of the human immune system, and many more. This tutorial describes the foundations of ABMS, identifies ABMS toolkits and development methods illustrated through a supply chain example, and provides thoughts on the appropriate contexts for ABMS versus conventional modeling techniques.

  14. Remote Agent Demonstration

    NASA Technical Reports Server (NTRS)

    Dorais, Gregory A.; Kurien, James; Rajan, Kanna

    1999-01-01

    We describe the computer demonstration of the Remote Agent Experiment (RAX). The Remote Agent is a high-level, model-based, autonomous control agent being validated on the NASA Deep Space 1 spacecraft.

  15. Chain entanglements. I. Theory

    NASA Astrophysics Data System (ADS)

    Fixman, Marshall

    1988-09-01

    A model of concentrated polymer solution dynamics is described. The forces in a linear generalized Langevin equation for the motion of a probe chain are derived on the assumption that all relaxation of the forces is due to motion of the surrounding matrix. Vicinal chain displacements are classified as viscoelastic deformation, reptation, and minor residual fluctuations. The latter provide a torsional relaxation of the primitive path that minimizes the significance of transverse forces on the probe chain. All displacements of vicinal segments are assumed proportional to the forces that they exert on the probe chain. In response to an external force, the displacement of the probe chain relative to a laboratory frame is increased by viscoelastic deformation of the matrix, but reptative diffusion relative to the deforming matrix is slowed down. The net effect on translational diffusion is negligible if the probe and vicinal chains have the same chain length N, but the friction constant for reptative motion is increased by a factor N1-xs. xs=1/2 if Gaussian conformational statistics applies during the disengagement process, while xs =0.6 if excluded volume statistics applies. The translational friction constant is βp ˜N2, as in reptation theory, but the viscosity is η˜N4-xs . The persistence of entanglements during the translational diffusion of the probe chain across many radii of gyration is rationalized pictorially in terms of correlated reptative motion of the probe and vicinal chains.

  16. Knitting distributed cluster-state ladders with spin chains

    SciTech Connect

    Ronke, R.; D'Amico, I.; Spiller, T. P.

    2011-09-15

    Recently there has been much study on the application of spin chains to quantum state transfer and communication. Here we discuss the utilization of spin chains (set up for perfect quantum state transfer) for the knitting of distributed cluster-state structures, between spin qubits repeatedly injected and extracted at the ends of the chain. The cluster states emerge from the natural evolution of the system across different excitation number sectors. We discuss the decohering effects of errors in the injection and extraction process as well as the effects of fabrication and random errors.

  17. Chemical Action of Halogenated Agents in Fire Extinguishing

    NASA Technical Reports Server (NTRS)

    Belles, Frank E.

    1955-01-01

    The action of halogenated agents in preventing flame propagation in fuel-air mixtures in laboratory tests is discussed in terms of a possible chemical mechanism. The mechanism chosen is that of chain-breaking reactions between agent and active particles (hydrogen and oxygen atoms and hydroxyl radicsls). Data from the literature on the flammability peaks of n-heptane agent-air mixtures are treated. Ratings of agent effectiveness in terms of the fuel equivalent of the agent, based on both fuel and agent concentrations at the peak, are proposed as preferable to ratings in terms of agent concentration alone. These fuel-equivalent ratings are roughly correlated by reactivities assigned to halogen and hydrogen atoms in the agent molecules. It is concluded that the presence of hydrogen in agent need not reduce its fire-fighting ability, provided there is enough halogen to make the agent nonflammable. A method is presented for estimating from quenching-distance data a rate constant for the reaction of agent with active particles. A quantitative result is obtained for methyl bromide. This rate constant predicts the observed peak concentration of methyl bromide quite well. However, more data are needed to prove the validity of the method. The assumption that hal.ogenatedagents act mainly by chain-bresking reactions with active particles is consistent with the experimental facts and should help guide the selection of agents for further tests.

  18. Respiratory chain cysteine and methionine usage indicate a causal role for thiyl radicals in aging.

    PubMed

    Moosmann, Bernd

    2011-01-01

    The identification of longevity-related structural adaptations in biological macromolecules may yield relevant insights into the molecular mechanisms of aging. In screening fully sequenced animal proteomes for signals associated with longevity, it was found that cysteine depletion in respiratory chain complexes was the by far strongest predictor on the amino acid usage level to co-vary with lifespan. This association was though restricted to aerobic animals, whereas anaerobic animals showed variable cysteine accumulation. By contrast, methionine accumulation, a prominent feature of mitochondrially encoded proteins affording competitive antioxidant protection, was not predictive of longevity, but rather paralleled aerobic metabolic capacity. Hence, the easily oxidized sulfur-containing amino acids cysteine (a thiol) and methionine (a thioether) show doubly diametrical behaviour in two central paradigms of respiratory oxidative stress. From this comparison, it is concluded that only the one-electron oxidation of thiols to thiyl radicals contributes to aging, whereas other forms of sulfur oxidation, especially even-electron oxidation of both thiols and thioethers, are less critically involved, presumably as their consequences may be much more easily repaired. Thiyl radicals may yet act as chain-transfer agents to entail an irreversible intramembrane cross-linking ("plastination") of some of the a priori most hydrophobic and insoluble proteins known, the respiratory chain complexes. PMID:20850516

  19. Chain Reaction Polymerization.

    ERIC Educational Resources Information Center

    McGrath, James E.

    1981-01-01

    The salient features and importance of chain-reaction polymerization are discussed, including such topics as the thermodynamics of polymerization, free-radical polymerization kinetics, radical polymerization processes, copolymers, and free-radical chain, anionic, cationic, coordination, and ring-opening polymerizations. (JN)

  20. Critical Chain Exercises

    ERIC Educational Resources Information Center

    Doyle, John Kevin

    2010-01-01

    Critical Chains project management focuses on holding buffers at the project level vs. task level, and managing buffers as a project resource. A number of studies have shown that Critical Chain project management can significantly improve organizational schedule fidelity (i.e., improve the proportion of projects delivered on time) and reduce…

  1. Synthesis of furanonaphthoquinones with hydroxyamino side chains.

    PubMed

    Wu, C; Johnson, R K; Mattern, M R; Wong, J C; Kingston, D G

    1999-07-01

    Several furanonaphthoquinones have shown useful activity in a yeast assay for DNA-damaging agents and cytotoxicity in mammalian cell culture assays. These results, together with the planar aromatic character of the furanonaphthoquinones, suggested that they might be acting as DNA intercalators. In an attempt to improve this activity, various analogues containing a hydroxyamino side chain have been synthesized. The analogues were prepared by standard methods, but some unexpected reactions were observed nonetheless. Thus, 8-formyl-5-methoxy-4,9-dihydronaphtho[2,3-b]furan-4,9-dione (24) showed an unusual reactivity toward reductive amination, with the reaction proceeding further to give one of two different cyclized products, depending on the amination reagent used. Bioassay results indicated that only simple furanonaphthoquines showed activity in a yeast assay for DNA-damaging agents; compounds with a substituted hydroxyamino side chain were uniformly inactive in this assay. Most of the compounds with a substituted hydroxyamino side chain on the furan ring did, however, show cytotoxicity, although none of them was any more active than the simple aldehyde 2-formyl-4, 9-dihydronaphtho[2,3-b]furan-4,9-dione (14). This evidence tends to suggest that the furanonaphthoquinones do not serve primarily as DNA intercalators, because if this were the case, they would have been expected to show an increased activity on conversion to their hydroxyamino side chain derivatives. PMID:10425117

  2. Chain-amplified photochemical fragmentation of N-alkoxypyridinium salts: proposed reaction of alkoxyl radicals with pyridine bases to give pyridinyl radicals.

    PubMed

    Shukla, Deepak; Adiga, Shashishekar P; Ahearn, Wendy G; Dinnocenzo, Joseph P; Farid, Samir

    2013-03-01

    Photoinduced electron transfer to N-alkoxypyridiniums, which leads to N–O bond cleavage and alkoxyl radical formation, is highly chain amplified in the presence of a pyridine base such as lutidine. Density functional theory calculations support a mechanism in which the alkoxyl radicals react with lutidine via proton-coupled electron transfer (PCET) to produce lutidinyl radicals (BH•). A strong electron donor, BH• is proposed to reduce another alkoxypyridinium cation, leading to chain amplification, with quantum yields approaching 200. Kinetic data and calculations support the formation of a second, stronger reducing agent: a hydrogen-bonded complex between BH• and another base molecule (BH•···B). Global fitting of the quantum yield data for the reactions of four pyridinium salts (4-phenyl and 4-cyano with N-methoxy and N-ethoxy substituents) led to a consistent set of kinetic parameters. The chain nature of the reaction allowed rate constants to be determined from steady-state kinetics and independently determined chain-termination rate constants. The rate constant of the reaction of CH3O• with lutidine to form BH•, k1, is ~6 × 10(6) M(–1) s(–1); that of CH3CH2O• is ~9 times larger. Reaction of CD3O• showed a deuterium isotope effect of ~6.5. Replacing lutidine by 3-chloropyridine, a weaker base, decreases k1 by a factor of ~400. PMID:23181705

  3. Pragmatic Transfer.

    ERIC Educational Resources Information Center

    Kasper, Gabriele

    1992-01-01

    Attempting to clarify the concept of pragmatic transfer, this article proposes as a basic distinction Leech/Thomas' dichotomy of sociopragmatics versus pragmalinguistics, presenting evidence for transfer at both levels. Issues discussed include pragmatic universals in speech act realization, conditions for pragmatic transfer, communicative…

  4. The NDUFB6 subunit of the mitochondrial respiratory chain complex I is required for electron transfer activity: A proof of principle study on stable and controlled RNA interference in human cell lines

    SciTech Connect

    Loublier, Sandrine; Bayot, Aurelien; Rak, Malgorzata; El-Khoury, Riyad; Benit, Paule; Rustin, Pierre

    2011-10-22

    Highlights: {yields} NDUFB6 is required for activity of mitochondrial complex I in human cell lines. {yields} Lentivirus based RNA interference results in frequent off target insertions. {yields} Flp-In recombinase mediated miRNA insertion allows gene-specific extinction. -- Abstract: Molecular bases of inherited deficiencies of mitochondrial respiratory chain complex I are still unknown in a high proportion of patients. Among 45 subunits making up this large complex, more than half has unknown function(s). Understanding the function of these subunits would contribute to our knowledge on mitochondrial physiology but might also reveal that some of these subunits are not required for the catalytic activity of the complex. A direct consequence of this finding would be the reduction of the number of candidate genes to be sequenced in patients with decreased complex I activity. In this study, we tested two different methods to stably extinct complex I subunits in cultured cells. We first found that lentivirus-mediated shRNA expression frequently resulted in the unpredicted extinction of additional gene(s) beside targeted ones. This can be ascribed to uncontrolled genetic material insertions in the genome of the host cell. This approach thus appeared inappropriate to study unknown functions of a gene. Next, we found it possible to specifically extinct a CI subunit gene by direct insertion of a miR targeting CI subunits in a Flp site (HEK293 Flp-In cells). By using this strategy we unambiguously demonstrated that the NDUFB6 subunit is required for complex I activity, and defined conditions suitable to undertake a systematic and stable extinction of the different supernumerary subunits in human cells.

  5. Ligand-to-ligand charge-transfer transitions of platinum(II) complexes with arylacetylide ligands with different chain lengths: spectroscopic characterization, effect of molecular conformations, and density functional theory calculations.

    PubMed

    Tong, Glenna So Ming; Law, Yuen-Chi; Kui, Steven C F; Zhu, Nianyong; Leung, King Hong; Phillips, David Lee; Che, Chi-Ming

    2010-06-11

    The complexes [Pt(tBu(3)tpy){C[triple bond]C(C(6)H(4)C[triple bond]C)(n-1)R}](+) (n = 1: R = alkyl and aryl (Ar); n = 1-3: R = phenyl (Ph) or Ph-N(CH(3))(2)-4; n = 1 and 2, R = Ph-NH(2)-4; tBu(3)tpy = 4,4',4''-tri-tert-butyl-2,2':6',2''-terpyridine) and [Pt(Cl(3)tpy)(C[triple bond]CR)](+) (R = tert-butyl (tBu), Ph, 9,9'-dibutylfluorene, 9,9'-dibutyl-7-dimethyl-amine-fluorene; Cl(3)tpy = 4,4',4''-trichloro-2,2':6',2''-terpyridine) were prepared. The effects of substituent(s) on the terpyridine (tpy) and acetylide ligands and chain length of arylacetylide ligands on the absorption and emission spectra were examined. Resonance Raman (RR) spectra of [Pt(tBu(3)tpy)(C[triple bond]CR)](+) (R = n-butyl, Ph, and C(6)H(4)-OCH(3)-4) obtained in acetonitrile at 298 K reveal that the structural distortion of the C[triple bond]C bond in the electronic excited state obtained by 502.9 nm excitation is substantially larger than that obtained by 416 nm excitation. Density functional theory (DFT) and time-dependent DFT (TDDFT) calculations on [Pt(H(3)tpy)(C[triple bond]CR)](+) (R = n-propyl (nPr), 2-pyridyl (Py)), [Pt(H(3)tpy){C[triple bond]C(C(6)H(4)C[triple bond]C)(n-1)Ph}](+) (n = 1-3), and [Pt(H(3)tpy){C[triple bond]C(C(6)H(4)C[triple bond]C)(n-1)C(6)H(4)-N(CH(3))(2)-4}](+)/+H(+) (n = 1-3; H(3)tpy = nonsubstituted terpyridine) at two different conformations were performed, namely, with the phenyl rings of the arylacetylide ligands coplanar ("cop") with and perpendicular ("per") to the H(3)tpy ligand. Combining the experimental data and calculated results, the two lowest energy absorption peak maxima, lambda(1) and lambda(2), of [Pt(Y(3)tpy)(C[triple bond]CR)](+) (Y = tBu or Cl, R = aryl) are attributed to (1)[pi(C[triple bond]CR)-->pi*(Y(3)tpy)] in the "cop" conformation and mixed (1)[d(pi)(Pt)-->pi*(Y(3)tpy)]/(1)[pi(C[triple bond]CR)-->pi*(Y(3)tpy)] transitions in the "per" conformation. The lowest energy absorption peak lambda(1) for [Pt(tBu(3)tpy){C[triple bond]C(C(6)H(4)C

  6. Fluorescence quenching of flavins by reductive agents

    NASA Astrophysics Data System (ADS)

    Penzkofer, A.; Bansal, A. K.; Song, S.-H.; Dick, B.

    2007-07-01

    The fluorescence behaviour of the flavins riboflavin, flavin mononucleotide (FMN), flavin adenine dinucleotide (FAD), and lumiflavin in aqueous solution at pH 8 in the presence of the reducing agents β-mercaptoethanol (β-ME), dithiothreitol (DTT), and sodium nitrite (NaNO 2) is studied under aerobic conditions. The fluorescence quantum yields and fluorescence lifetimes are determined as a function of the reducing agent concentration. For all three reducing agents diffusion controlled dynamic fluorescence quenching is observed which is thought to be due to photo-induced reductive electron transfer. For DTT additionally static fluorescence quenching occurs.

  7. Microwave-assisted solid-phase synthesis of side-chain to side-chain lactam-bridge cyclic peptides.

    PubMed

    Tala, Srinivasa R; Schnell, Sathya M; Haskell-Luevano, Carrie

    2015-12-15

    Side-chain to side-chain lactam-bridged cyclic peptides have been utilized as therapeutic agents and biochemical tools. Previous synthetic methods of these peptides need special reaction conditions, form side products and take longer reaction times. Herein, an efficient microwave-assisted synthesis of side-chain to side-chain lactam-bridge cyclic peptides SHU9119 and MTII is reported. The synthesis time and efforts are significantly reduced in the present method, without side product formation. The analytical and pharmacological data of the synthesized cyclic peptides are in accordance with the commercially obtained compounds. This new method could be used to synthesize other side-chain to side-chain lactam-bridge peptides and amenable to automation and extensive SAR compound derivatization. PMID:26555357

  8. Technology transfer

    NASA Technical Reports Server (NTRS)

    Handley, Thomas

    1992-01-01

    The requirements for a successful technology transfer program and what such a program would look like are discussed. In particular, the issues associated with technology transfer in general, and within the Jet Propulsion Laboratory (JPL) environment specifically are addressed. The section on background sets the stage, identifies the barriers to successful technology transfer, and suggests actions to address the barriers either generally or specifically. The section on technology transfer presents a process with its supporting management plan that is required to ensure a smooth transfer process. Viewgraphs are also included.

  9. SUMO chains: polymeric signals.

    PubMed

    Vertegaal, Alfred C O

    2010-02-01

    Ubiquitin and ubiquitin-like proteins are conjugated to a wide variety of target proteins that play roles in all biological processes. Target proteins are conjugated to ubiquitin monomers or to ubiquitin polymers that form via all seven internal lysine residues of ubiquitin. The fate of these target proteins is controlled in a chain architecture-dependent manner. SUMO (small ubiquitin-related modifier) shares the ability of ubiquitin to form chains via internal SUMOylation sites. Interestingly, a SUMO-binding site in Ubc9 is important for SUMO chain synthesis. Similar to ubiquitin-polymer cleavage by USPs (ubiquitin-specific proteases), SUMO chain formation is reversible. SUMO polymers are cleaved by the SUMO proteases SENP6 [SUMO/sentrin/SMT3 (suppressor of mif two 3)-specific peptidase 6], SENP7 and Ulp2 (ubiquitin-like protease 2). SUMO chain-binding proteins including ZIP1, SLX5/8 (synthetic lethal of unknown function 5/8), RNF4 (RING finger protein 4) and CENP-E (centromere-associated protein E) have been identified that interact non-covalently with SUMO chains, thereby regulating target proteins that are conjugated to SUMO multimers. SUMO chains play roles in replication, in the turnover of SUMO targets by the proteasome and during mitosis and meiosis. Thus signalling via polymers is an exciting feature of the SUMO family. PMID:20074033

  10. Can Space Applications Benefit from Intelligent Agents?

    NASA Astrophysics Data System (ADS)

    Varghese, Blesson; McKee, Gerard

    The work reported in this paper proposes a Swarm-Array computing approach based on 'Intelligent Agents' to apply autonomic computing concepts to parallel computing systems and build reliable systems for space applications. Swarm-array computing is a swarm robotics inspired, novel computing approach considered as a path to achieve autonomy in parallel computing systems. In the intelligent agent approach, a task to be executed on parallel computing cores is considered as a swarm of autonomous agents. A task is carried to a computing core by carrier agents and can be seamlessly transferred between cores in the event of a predicted failure, thereby achieving self-* objectives of autonomic computing. The approach is validated on a multi-agent simulator.

  11. Spacecraft sanitation agent development

    NASA Technical Reports Server (NTRS)

    1972-01-01

    The development of an effective sanitizing agent that is compatible with the spacecraft environment and the human occupant is discussed. Experimental results show that two sanitation agents must be used to satisfy mission requirements: one agent for personal hygiene and one for equipment maintenance. It was also recommended that a water rinse be used with the agents for best results, and that consideration be given to using the agents pressure packed or in aerosol formulations.

  12. Characterization of chemical agent transport in paints.

    PubMed

    Willis, Matthew P; Gordon, Wesley; Lalain, Teri; Mantooth, Brent

    2013-09-15

    A combination of vacuum-based vapor emission measurements with a mass transport model was employed to determine the interaction of chemical warfare agents with various materials, including transport parameters of agents in paints. Accurate determination of mass transport parameters enables the simulation of the chemical agent distribution in a material for decontaminant performance modeling. The evaluation was performed with the chemical warfare agents bis(2-chloroethyl) sulfide (distilled mustard, known as the chemical warfare blister agent HD) and O-ethyl S-[2-(diisopropylamino)ethyl] methylphosphonothioate (VX), an organophosphate nerve agent, deposited on to two different types of polyurethane paint coatings. The results demonstrated alignment between the experimentally measured vapor emission flux and the predicted vapor flux. Mass transport modeling demonstrated rapid transport of VX into the coatings; VX penetrated through the aliphatic polyurethane-based coating (100 μm) within approximately 107 min. By comparison, while HD was more soluble in the coatings, the penetration depth in the coatings was approximately 2× lower than VX. Applications of mass transport parameters include the ability to predict agent uptake, and subsequent long-term vapor emission or contact transfer where the agent could present exposure risks. Additionally, these parameters and model enable the ability to perform decontamination modeling to predict how decontaminants remove agent from these materials. PMID:23872337

  13. Translocation of reptating chains

    NASA Astrophysics Data System (ADS)

    Żurek, S.; Drzewiński, A.; van Leeuwen, J. M. J.

    2011-05-01

    Voltage-driven translocation is modeled with the Rubinstein-Duke rules for hopping reptons in one- and two-dimensional lattices. The chain is driven through the pore by a bias potential promoting the transition of stored length in one direction. Coupling states give a semi-periodicity of the process that enables us to relate the properties to the stationary state of the master equation. The exact solution for short chains and Monte Carlo simulations for longer chains are used to calculate displacements, velocities and the translocation time.

  14. Substrate Effects for Atomic Chain Electronics

    NASA Technical Reports Server (NTRS)

    Yamada, Toshishige; Saini, Subhash (Technical Monitor)

    1998-01-01

    A substrate for future atomic chain electronics, where adatoms are placed at designated positions and form atomically precise device components, is studied theoretically. The substrate has to serve as a two-dimensional template for adatom mounting with a reasonable confinement barrier and also provide electronic isolation, preventing unwanted coupling between independent adatom structures. For excellent structural stability, we demand chemical bonding between the adatoms and substrate atoms, but then good electronic isolation may not be guaranteed. Conditions are clarified for good isolation. Because of the chemical bonding, fundamental adatom properties are strongly influenced: a chain with group IV adatoms having two chemical bonds, or a chain with group III adatoms having one chemical bond is semiconducting. Charge transfer from or to the substrate atoms brings about unintentional doping, and the electronic properties have to be considered for the entire combination of the adatom and substrate systems even if the adatom modes are well localized at the surface.

  15. Kinetic chain abnormalities in the athletic shoulder.

    PubMed

    Sciascia, Aaron; Thigpen, Charles; Namdari, Surena; Baldwin, Keith

    2012-03-01

    Overhead activities require the shoulder to be exposed to and sustain repetitive loads. The segmental activation of the body's links, known as the kinetic chain, allows this to occur effectively. Proper muscle activation is achieved through generation of energy from the central segment or core, which then transfers the energy to the terminal links of the shoulder, elbow, and hand. The kinetic chain is best characterized by 3 components: optimized anatomy, reproducible efficient motor patterns, and the sequential generation of forces. However, tissue injury and anatomic deficits such as weakness and/or tightness in the leg, pelvic core, or scapular musculature can lead to overuse shoulder injuries. These injuries can be prevented and maladaptations can be detected with a thorough understanding of biomechanics of the kinetic chain as it relates to overhead activity. PMID:22311288

  16. Predicting the chemical stability of monatomic chains

    NASA Astrophysics Data System (ADS)

    Lin, Zheng-Zhe; Chen, Xi

    2013-02-01

    A simple model for evaluating the thermal atomic transfer rates in nanosystems (Lin Z.-Z. et al., EPL, 94 (2011) 40002) was developed to predict the chemical reaction rates of nanosystems with small gas molecules. The accuracy of the model was verified by MD simulations for molecular adsorption and desorption on a monatomic chain. By the prediction, a monatomic carbon chain should survive for 1.2 × 102 years in the ambient of 1 atm O2 at room temperature, and it is very invulnerable to N2, H2O, NO2, CO and CO2, while a monatomic gold chain quickly ruptures in vacuum. It is worth noting that since the model can be easily applied via common ab initio calculations, it could be widely used in the prediction of chemical stability of nanosystems.

  17. BART: Bayesian Atmospheric Radiative Transfer fitting code

    NASA Astrophysics Data System (ADS)

    Cubillos, Patricio; Blecic, Jasmina; Harrington, Joseph; Rojo, Patricio; Lust, Nate; Bowman, Oliver; Stemm, Madison; Foster, Andrew; Loredo, Thomas J.; Fortney, Jonathan; Madhusudhan, Nikku

    2016-08-01

    BART implements a Bayesian, Monte Carlo-driven, radiative-transfer scheme for extracting parameters from spectra of planetary atmospheres. BART combines a thermochemical-equilibrium code, a one-dimensional line-by-line radiative-transfer code, and the Multi-core Markov-chain Monte Carlo statistical module to constrain the atmospheric temperature and chemical-abundance profiles of exoplanets.

  18. Practicality of spin chain wiring in diamond quantum technologies.

    PubMed

    Ping, Yuting; Lovett, Brendon W; Benjamin, Simon C; Gauger, Erik M

    2013-03-01

    Coupled spin chains are promising candidates for wiring up qubits in solid-state quantum computing (QC). In particular, two nitrogen-vacancy centers in diamond can be connected by a chain of implanted nitrogen impurities; when driven by suitable global fields the chain can potentially enable quantum state transfer at room temperature. However, our detailed analysis of error effects suggests that foreseeable systems may fall far short of the fidelities required for QC. Fortunately the chain can function in the more modest role as a mediator of noisy entanglement, enabling QC provided that we use subsequent purification. For instance, a chain of 5 spins with interspin distances of 10 nm has finite entangling power as long as the T(2) time of the spins exceeds 0.55 ms. Moreover we show that repurposing the chain this way can remove the restriction to nearest-neighbor interactions, so eliminating the need for complicated dynamical decoupling sequences. PMID:23521240

  19. Atomic Chain Electronics

    NASA Technical Reports Server (NTRS)

    Yamada, Toshishige; Saini, Subhash (Technical Monitor)

    1998-01-01

    Adatom chains, precise structures artificially created on an atomically regulated surface, are the smallest possible candidates for future nanoelectronics. Since all the devices are created by combining adatom chains precisely prepared with atomic precision, device characteristics are predictable, and free from deviations due to accidental structural defects. In this atomic dimension, however, an analogy to the current semiconductor devices may not work. For example, Si structures are not always semiconducting. Adatom states do not always localize at the substrate surface when adatoms form chemical bonds to the substrate atoms. Transport properties are often determined for the entire system of the chain and electrodes, and not for chains only. These fundamental issues are discussed, which will be useful for future device considerations.

  20. Factorialsum Number Chains.

    ERIC Educational Resources Information Center

    Lamb, John, Jr.

    1989-01-01

    Describes several phenomena in which interesting properties of numbers are demonstrated. Includes discussions of amicable, perfect, and sociable numbers. Presents computer programs for conducting a number chain search. (RT)

  1. A simulation framework for mapping risks in clinical processes: the case of in-patient transfers

    PubMed Central

    Ong, Mei-Sing; Westbrook, Johanna I; Magrabi, Farah; Coiera, Enrico; Wobcke, Wayne

    2011-01-01

    Objective To model how individual violations in routine clinical processes cumulatively contribute to the risk of adverse events in hospital using an agent-based simulation framework. Design An agent-based simulation was designed to model the cascade of common violations that contribute to the risk of adverse events in routine clinical processes. Clinicians and the information systems that support them were represented as a group of interacting agents using data from direct observations. The model was calibrated using data from 101 patient transfers observed in a hospital and results were validated for one of two scenarios (a misidentification scenario and an infection control scenario). Repeated simulations using the calibrated model were undertaken to create a distribution of possible process outcomes. The likelihood of end-of-chain risk is the main outcome measure, reported for each of the two scenarios. Results The simulations demonstrate end-of-chain risks of 8% and 24% for the misidentification and infection control scenarios, respectively. Over 95% of the simulations in both scenarios are unique, indicating that the in-patient transfer process diverges from prescribed work practices in a variety of ways. Conclusions The simulation allowed us to model the risk of adverse events in a clinical process, by generating the variety of possible work subject to violations, a novel prospective risk analysis method. The in-patient transfer process has a high proportion of unique trajectories, implying that risk mitigation may benefit from focusing on reducing complexity rather than augmenting the process with further rule-based protocols. PMID:21486883

  2. Light chain nephropathy.

    PubMed

    Darouich, Sihem; Bettaieb, Ilhem; Aouadia, Raja; Hedri, Hafedh; Abderrahim, Ezzeddine; Goucha, Rym; Khedher, Adel

    2015-01-01

    Light chain deposition disease (LCDD) is characterized by the tissue deposition of monotypic immunoglobulin light chains of either kappa or lambda isotype. It is the archetypal systemic disease that is most frequently diagnosed on a kidney biopsy, although the deposits may involve several other organs. This brief review focuses on the clinicopathological features of LCDD-associated nephropathy with an emphasis on the diagnostic and therapeutic difficulties related to this elusive condition. PMID:26022011

  3. Technology transfer

    NASA Technical Reports Server (NTRS)

    Penaranda, Frank E.

    1992-01-01

    The topics are presented in viewgraph form and include the following: international comparison of R&D expenditures in 1989; NASA Technology Transfer Program; NASA Technology Utilization Program thrusts for FY 1992 and FY 1993; National Technology Transfer Network; and NTTC roles.

  4. Phasic Triplet Markov Chains.

    PubMed

    El Yazid Boudaren, Mohamed; Monfrini, Emmanuel; Pieczynski, Wojciech; Aïssani, Amar

    2014-11-01

    Hidden Markov chains have been shown to be inadequate for data modeling under some complex conditions. In this work, we address the problem of statistical modeling of phenomena involving two heterogeneous system states. Such phenomena may arise in biology or communications, among other fields. Namely, we consider that a sequence of meaningful words is to be searched within a whole observation that also contains arbitrary one-by-one symbols. Moreover, a word may be interrupted at some site to be carried on later. Applying plain hidden Markov chains to such data, while ignoring their specificity, yields unsatisfactory results. The Phasic triplet Markov chain, proposed in this paper, overcomes this difficulty by means of an auxiliary underlying process in accordance with the triplet Markov chains theory. Related Bayesian restoration techniques and parameters estimation procedures according to the new model are then described. Finally, to assess the performance of the proposed model against the conventional hidden Markov chain model, experiments are conducted on synthetic and real data. PMID:26353069

  5. Hydroxypyridonate chelating agents

    DOEpatents

    Raymond, Kenneth N.; Scarrow, Robert C.; White, David L.

    1987-01-01

    Chelating agents having 1-hydroxy-2-pyridinone (HOPO) and related moieties incorporated within their structures, including polydentate HOPO-substituted polyamines such as spermidine and spermine, and HOPO-substituted desferrioxamine. The chelating agents are useful in selectively removing certain cations from solution, and are particularly useful as ferric ion and actinide chelators. Novel syntheses of the chelating agents are provided.

  6. Mobile Agents Applications.

    ERIC Educational Resources Information Center

    Martins, Rosane Maria; Chaves, Magali Ribeiro; Pirmez, Luci; Rust da Costa Carmo, Luiz Fernando

    2001-01-01

    Discussion of the need to filter and retrieval relevant information from the Internet focuses on the use of mobile agents, specific software components which are based on distributed artificial intelligence and integrated systems. Surveys agent technology and discusses the agent building package used to develop two applications using IBM's Aglet…

  7. Possession, use, and transfer of select agents and toxins--reconstructed replication competent forms of the 1918 pandemic influenza virus containing any portion of the coding regions of all eight gene segments. Interim final rule.

    PubMed

    2005-10-20

    We are adding reconstructed replication competent forms of the 1918 pandemic influenza virus containing any portion of the coding regions of all eight gene segments to the list of HHS select agents and toxins. We are taking this action for several reasons. First the pandemic influenza virus of 1918-19 killed up to 50 million people worldwide, including an estimated 675,000 deaths in the United States. Also, the complete coding sequence for the 1918 pandemic influenza A H1N1 virus was recently identified, which will make it possible for those with knowledge of reverse genetics to reconstruct this virus. In addition, the first published study on a reconstructed 1918 pandemic influenza virus demonstrated the high virulence of this virus in cell culture, embryonated eggs, and in mice relative to other human influenza viruses. Therefore, we have determined that the reconstructed replication competent forms of the 1918 pandemic influenza virus containing any portion of the coding regions of all eight gene segments have the potential to pose a severe threat to public health and safety. PMID:16237858

  8. Chain formation and chain dynamics in a dilute magnetorheological fluid.

    PubMed

    Hagenbüchle, M; Liu, J

    1997-10-20

    Magnetorheological fluids are suspensions of magnetizable particles that reversibly change from liquid to solid when subjected to a magnetic field. A field-induced structure of dipolar chains is responsible for these changes. Our work aimed at understanding chain dynamics and the kinetics of chain formation by using dynamic light scattering. Chain length is determined by measurement of the diffusion coefficient. Chain-length growth shows a Smoluchowski behavior. PMID:18264283

  9. Pre-validation study for testing of avian viral vaccines for extraneous agents by PCR.

    PubMed

    Bruckner, L; Ottiger, H P

    2007-12-01

    The biological nature of vaccines imposes a permanent risk for contamination with extraneous agents. Therefore, testing of vaccines for freedom from extraneous agents is essential in the manufacturing process and quality control. Relevant methods for testing for extraneous agents of avian viral vaccines are specified in the monographs of the European Pharmacopoeia (Ph. Eur.). Currently, most of these methods involve the use of embryonated eggs or chickens. Polymerase chain reaction (PCR) is a widely used and suitable tool for the amplification and detection of extraneous nucleic acids. Different PCR assays have been developed for the application in routine testing of veterinary vaccines. However, before introduction of new methods in monographs of the Ph. Eur., they must undergo validation. Here we report about a pre-validation study performed in Official Medicines Control Laboratories (OMCLs). Diluted samples of avian infectious laryngotracheitis, avian infectious bronchitis and avian infectious bursal disease viruses have been analysed using standardised procedures and reagents. The study demonstrated that PCR methods can be transferred to other laboratories. The results also show that further work is warranted for full validation of the method. PMID:18413134

  10. Spatial Data Supply Chains

    NASA Astrophysics Data System (ADS)

    Varadharajulu, P.; Azeem Saqiq, M.; Yu, F.; McMeekin, D. A.; West, G.; Arnold, L.; Moncrieff, S.

    2015-06-01

    This paper describes current research into the supply of spatial data to the end user in as close to real time as possible via the World Wide Web. The Spatial Data Infrastructure paradigm has been discussed since the early 1990s. The concept has evolved significantly since then but has almost always examined data from the perspective of the supplier. It has been a supplier driven focus rather than a user driven focus. The current research being conducted is making a paradigm shift and looking at the supply of spatial data as a supply chain, similar to a manufacturing supply chain in which users play a significant part. A comprehensive consultation process took place within Australia and New Zealand incorporating a large number of stakeholders. Three research projects that have arisen from this consultation process are examining Spatial Data Supply Chains within Australia and New Zealand and are discussed within this paper.

  11. Standard Agent Framework 1

    SciTech Connect

    Goldsmith, Steven Y.

    1999-04-06

    The Standard Agent framework provides an extensible object-oriented development environment suitable for use in both research and applications projects. The SAF provides a means for constructing and customizing multi-agent systems through specialization of standard base classes (architecture-driven framework) and by composition of component classes (data driven framework). The standard agent system is implemented as an extensible object-centerd framework. Four concrete base classes are developed: (1) Standard Agency; (2) Standard Agent; (3) Human Factor, and (4) Resources. The object-centered framework developed and utilized provides the best comprimise between generality and flexibility available in agent development systems today.

  12. Supply-Chain Optimization Template

    NASA Technical Reports Server (NTRS)

    Quiett, William F.; Sealing, Scott L.

    2009-01-01

    The Supply-Chain Optimization Template (SCOT) is an instructional guide for identifying, evaluating, and optimizing (including re-engineering) aerospace- oriented supply chains. The SCOT was derived from the Supply Chain Council s Supply-Chain Operations Reference (SCC SCOR) Model, which is more generic and more oriented toward achieving a competitive advantage in business.

  13. Solitons in Granular Chains

    SciTech Connect

    Manciu, M.; Sen, S.; Hurd, A.J.

    1999-04-12

    The authors consider a chain of elastic (Hertzian) grains that repel upon contact according to the potential V = a{delta}{sup u}, u > 2, where {delta} is the overlap between the grains. They present numerical and analytical results to show that an impulse initiated at an end of a chain of Hertzian grains in contact eventually propagates as a soliton for all n > 2 and that no solitons are possible for n {le} 2. Unlike continuous, they find that colliding solitons in discrete media initiative multiple weak solitons at the point of crossing.

  14. Polyisobutylene chain end transformations: Block copolymer synthesis and click chemistry functionalizations

    NASA Astrophysics Data System (ADS)

    Magenau, Andrew Jackson David

    The primary objectives of this research were twofold: (1) development of synthetic procedures for combining quasiliving carbocationic polymerization (QLCCP) of isobutylene (IB) and reversible addition fragmentation chain transfer (RAFT) polymerization for block copolymer synthesis; (2) utilization of efficient, robust, and modular chemistries for facile functionalization of polyisobutylene (PIB). In the first study block copolymers consisting of PIB, and either PMMA or PS block segments, were synthesized by a site transformation approach combining living cationic and reversible addition-fragmentation chain transfer (RAFT) polymerizations. The initial PIB block was synthesized via quasiliving cationic polymerization using the TMPCl/TiCl4 initiation system and was subsequently converted into a hydroxylterminated PIB. Site transformation of the hydroxyl-terminated PIB into a macro chain transfer agent (PIB-CTA) was accomplished by N,N'-dicyclohexylcarbodiimide/dimethylaminopyridine-catalyzed esterification with 4-cyano-4-(dodecylsulfanylthiocarbonylsulfanyl)pentanoic acid. In the second study another site transformation approach was developed to synthesize a novel block copolymer, composed of PIB and PNIPAM segments. The PIB block was prepared via quasiliving cationic polymerization and end functionalized by in-situ quenching to yield telechelic halogen-terminated PIB. Azido functionality was obtained by displacement of the terminal halogen through nucleophilic substitution, which was confirmed by both 1H and 13C NMR. Coupling of an alkyne-functional chain transfer agent (CTA) to azido PIB was successfully accomplished through a copper catalyzed click reaction. Structure of the resulting PIB-based macro-CTA was verified with 1H NMR, FTIR, and GPC; whereas coupling reaction kinetics were monitored by real time variable temperature (VT) 1H NMR. In a third study, a click chemistry functionalization procedure was developed based upon the azide-alkyne 1,3-dipolar

  15. Transport of triplet excitons along continuous 100 nm polyfluorene chains

    SciTech Connect

    Xi, Liang; Bird, Matthew; Mauro, Gina; Asaoka, Sadayuki; Cook, Andrew R.; Chen, Hung -Cheng; Miller, John R.

    2014-12-03

    Triplet excitons created in poly-2,7-(9,9-dihexyl)fluorene (pF) chains with end trap groups in solution are efficiently transported to and captured by the end groups. The triplets explore the entire lengths of the chains, even for ~100 nm long chains enabling determination of the completeness of end capping. The results show that the chains continuous: they may contain transient barriers or traps, such as those from fluctuations of dihedral angles, but are free of major defects that stop motion of the triplets. Quantitative determinations are aided by the addition of a strong electron donor, TMPD, which removes absorption bands of the end-trapped triplets. For chains having at least one end trap, triplet capture is quantitative on the 1 µs timescale imposed by the use of the donor. Fractions of chains having no end traps were 0.15 for pF samples with anthraquinone (AQ) end traps and 0.063 with naphthylimide (NI) end traps. These determinations agreed with measurements by NMR for short (<40 polymer repeat units (PRU)) chains, where NMR determinations are accurate. The results find no evidence for traps or barriers to transport of triplets, and places limits on the possible presence of defects as impenetrable barriers to less than one per 300 PRU. The present results present a paradigm different from the current consensus, derived from observations of singlet excitons, that conjugated chains are divided into “segments,” perhaps by some kind of defects. For the present pF chains, the segmentation either does not apply to triplet excitons or is transient so that the defects are healed or surmounted in times much shorter than 1 µs. Triplets on chains without end trap groups transfer to chains with end traps on a slower time scale. Rate constants for these bimolecular triplet transfer reactions were found to increase with the length of the accepting chain, as did rate constants for triplet transfer to the chains from small molecules like biphenyl. As a result, a

  16. Transport of triplet excitons along continuous 100 nm polyfluorene chains

    DOE PAGESBeta

    Xi, Liang; Bird, Matthew; Mauro, Gina; Asaoka, Sadayuki; Cook, Andrew R.; Chen, Hung -Cheng; Miller, John R.

    2014-12-03

    Triplet excitons created in poly-2,7-(9,9-dihexyl)fluorene (pF) chains with end trap groups in solution are efficiently transported to and captured by the end groups. The triplets explore the entire lengths of the chains, even for ~100 nm long chains enabling determination of the completeness of end capping. The results show that the chains continuous: they may contain transient barriers or traps, such as those from fluctuations of dihedral angles, but are free of major defects that stop motion of the triplets. Quantitative determinations are aided by the addition of a strong electron donor, TMPD, which removes absorption bands of the end-trappedmore » triplets. For chains having at least one end trap, triplet capture is quantitative on the 1 µs timescale imposed by the use of the donor. Fractions of chains having no end traps were 0.15 for pF samples with anthraquinone (AQ) end traps and 0.063 with naphthylimide (NI) end traps. These determinations agreed with measurements by NMR for short (<40 polymer repeat units (PRU)) chains, where NMR determinations are accurate. The results find no evidence for traps or barriers to transport of triplets, and places limits on the possible presence of defects as impenetrable barriers to less than one per 300 PRU. The present results present a paradigm different from the current consensus, derived from observations of singlet excitons, that conjugated chains are divided into “segments,” perhaps by some kind of defects. For the present pF chains, the segmentation either does not apply to triplet excitons or is transient so that the defects are healed or surmounted in times much shorter than 1 µs. Triplets on chains without end trap groups transfer to chains with end traps on a slower time scale. Rate constants for these bimolecular triplet transfer reactions were found to increase with the length of the accepting chain, as did rate constants for triplet transfer to the chains from small molecules like biphenyl. As a

  17. The Relationship between Organizational Transfer Climate and Positive Transfer of Training.

    ERIC Educational Resources Information Center

    Rouiller, Janice Z; Goldstein, Irwin L.

    1993-01-01

    After a 9-week training course, 102 manager trainees in a fast-food chain were assigned to restaurants. Those assigned to units having positive organizational transfer climate (measured by situational cues and consequences) were rated as better performers. Climate affected the degree to which learned behavior was transferred to the actual job. (SK)

  18. INTERACTING QUANTUM SPIN CHAINS

    SciTech Connect

    ZHELUDEV,A.

    2001-09-09

    A brief review of recent advances in neutron scattering studies of low-dimensional quantum magnets is followed by a particular example. The separation of single-particle and continuum states in the weakly-coupled S = l/2 chains system BaCu{sub 2}Si{sub 2}O{sub 7} is described in some detail.

  19. Exploration Supply Chain Simulation

    NASA Technical Reports Server (NTRS)

    2008-01-01

    The Exploration Supply Chain Simulation project was chartered by the NASA Exploration Systems Mission Directorate to develop a software tool, with proper data, to quantitatively analyze supply chains for future program planning. This tool is a discrete-event simulation that uses the basic supply chain concepts of planning, sourcing, making, delivering, and returning. This supply chain perspective is combined with other discrete or continuous simulation factors. Discrete resource events (such as launch or delivery reviews) are represented as organizational functional units. Continuous resources (such as civil service or contractor program functions) are defined as enabling functional units. Concepts of fixed and variable costs are included in the model to allow the discrete events to interact with cost calculations. The definition file is intrinsic to the model, but a blank start can be initiated at any time. The current definition file is an Orion Ares I crew launch vehicle. Parameters stretch from Kennedy Space Center across and into other program entities (Michaud Assembly Facility, Aliant Techsystems, Stennis Space Center, Johnson Space Center, etc.) though these will only gain detail as the file continues to evolve. The Orion Ares I file definition in the tool continues to evolve, and analysis from this tool is expected in 2008. This is the first application of such business-driven modeling to a NASA/government-- aerospace contractor endeavor.

  20. Heavy Chain Diseases

    MedlinePlus

    ... cells often prevents proper absorption of nutrients from food (malabsorption), resulting in severe diarrhea and weight loss. A rare form that affects the respiratory tract also exists. Blood tests are done when alpha heavy chain disease is suspected. Serum protein electrophoresis, measurement of ...

  1. Polymerase chain reaction system

    DOEpatents

    Benett, William J.; Richards, James B.; Stratton, Paul L.; Hadley, Dean R.; Milanovich, Fred P.; Belgrader, Phil; Meyer, Peter L.

    2004-03-02

    A portable polymerase chain reaction DNA amplification and detection system includes one or more chamber modules. Each module supports a duplex assay of a biological sample. Each module has two parallel interrogation ports with a linear optical system. The system is capable of being handheld.

  2. Atwood's Heavy Chain

    ERIC Educational Resources Information Center

    Beeken, Paul

    2011-01-01

    While perusing various websites in search of a more challenging lab for my students, I came across a number of ideas where replacing the string in an Atwood's machine with a simple ball chain like the kind found in lamp pulls created an interesting system to investigate. The replacement of the string produced a nice nonuniform acceleration, but…

  3. Breaking the Chains

    ERIC Educational Resources Information Center

    Stanistreet, Paul

    2007-01-01

    In 1792 more than 350,000 people in Britain signed a petition calling for an end to the slave trade. It was, writes historian Adam Hochschild in his book "Bury the Chains," "the first time in history that a large number of people became outraged, and stayed outraged for many years, over someone else's rights". In 1807--after 15 years of…

  4. NISAC Agent Based Laboratory for Economics

    SciTech Connect

    Downes, Paula; Davis, Chris; Eidson, Eric; Ehlen, Mark; Gieseler, Charles; Harris, Richard

    2006-10-11

    The software provides large-scale microeconomic simulation of complex economic and social systems (such as supply chain and market dynamics of businesses in the US economy) and their dependence on physical infrastructure systems. The system is based on Agent simulation, where each entity of inteest in the system to be modeled (for example, a Bank, individual firms, Consumer households, etc.) is specified in a data-driven sense to be individually repreented by an Agent. The Agents interact using rules of interaction appropriate to their roles, and through those interactions complex economic and social dynamics emerge. The software is implemented in three tiers, a Java-based visualization client, a C++ control mid-tier, and a C++ computational tier.

  5. NISAC Agent Based Laboratory for Economics

    Energy Science and Technology Software Center (ESTSC)

    2006-10-11

    The software provides large-scale microeconomic simulation of complex economic and social systems (such as supply chain and market dynamics of businesses in the US economy) and their dependence on physical infrastructure systems. The system is based on Agent simulation, where each entity of inteest in the system to be modeled (for example, a Bank, individual firms, Consumer households, etc.) is specified in a data-driven sense to be individually repreented by an Agent. The Agents interactmore » using rules of interaction appropriate to their roles, and through those interactions complex economic and social dynamics emerge. The software is implemented in three tiers, a Java-based visualization client, a C++ control mid-tier, and a C++ computational tier.« less

  6. Dioxin reservoirs in southern Viet Nam--a legacy of Agent Orange.

    PubMed

    Dwernychuk, L Wayne; Cau, Hoang Dinh; Hatfield, Christopher T; Boivin, Thomas G; Hung, Tran Manh; Dung, Phung Tri; Thai, Nguyen Dinh

    2002-04-01

    In the isolated Aluoi Valley of central Viet Nam, very high levels of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) were measured in soil, fish fat, duck fat, pooled human blood and breast milk samples collected from A So village between 1996 and 1999. The village was situated on a former military base occupied by US Special Forces between 1963 and 1966. TCDD was a contaminant of the herbicide "Agent Orange", aerially sprayed in the valley between 1965 and 1970, and stored at the A So base. Measured levels were lower near the sites of two other former US bases in the valley which had been occupied for shorter periods of time. In areas where Agent Orange had been applied by low-flying aircraft, levels of TCDD in soil, food and human samples were elevated, but lower than those near the three former US bases. We confirm the apparent food chain transfer of TCDD from contaminated soil to cultured fish pond sediments to fish and duck tissues, then to humans as measured in whole blood and breast milk. We theorize that the Aluoi Valley is a microcosm of southern Viet Nam, where numerous reservoirs of TCDD exist in the soil of former military installations south of the former demilitarized zone. Large quantities of Agent Orange were stored at many sites, used in ground and aerial applications, and spilled. TCDD, through various forms of soil disturbance, can be mobilized from these reservoirs after decades below the surface, and subsequently, introduced into the human food chain. PMID:11993628

  7. Pure transfer

    NASA Astrophysics Data System (ADS)

    2014-03-01

    Spectral purity can now be transferred from one laser to another with a very different wavelength at an order of magnitude better than previously achievable. Yann Le Coq spoke to Nature Photonics about the new development.

  8. Biosecurity reference : CFR-listed agent and toxin summaries.

    SciTech Connect

    Barnett, Natalie Beth

    2003-09-01

    This reference document provides summary information on the animal, plant, zoonotic, and human pathogens and toxins regulated and categorized by 9 CFR 331 and 7 CFR 121, 'Agricultural Bioterrorism Protection Act of 2002; Possession, Use and Transfer of Biological Agents and Toxins,' and 42 CFR 73, 'Possession, Use, and Transfer of Select Agents and Toxins.' Summary information includes, at a minimum, a description of the agent and its associated symptoms; often additional information is provided on the diagnosis, treatment, geographic distribution, transmission, control and eradication, and impacts on public health.

  9. Biocatalytic reduction of short-chain carboxylic acids into their corresponding alcohols with syngas fermentation.

    PubMed

    Perez, Jose M; Richter, Hanno; Loftus, Sarah E; Angenent, Largus T

    2013-04-01

    Short-chain carboxylic acids generated by various mixed- or pure-culture fermentation processes have been considered valuable precursors for production of bioalcohols. While conversion of carboxylic acids into alcohols is routinely performed with catalytic hydrogenation or with strong chemical reducing agents, here, a biological conversion route was explored. The potential of carboxydotrophic bacteria, such as Clostridium ljungdahlii and Clostridium ragsdalei, as biocatalysts for conversion of short-chain carboxylic acids into alcohols, using syngas as a source of electrons and energy is demonstrated. Acetic acid, propionic acid, n-butyric acid, isobutyric acid, n-valeric acid, and n-caproic acid were converted into their corresponding alcohols. Furthermore, biomass yields and fermentation stoichiometry from the experimental data were modeled to determine how much metabolic energy C. ljungdahlii generated during syngas fermentation. An ATP yield of 0.4-0.5 mol of ATP per mol CO consumed was calculated in the presence of hydrogen. The ratio of protons pumped across the cell membrane versus electrons transferred from ferredoxin to NAD(+) via the Rnf complex is suggested to be 1.0. Based on these results, we provide suggestions how n-butyric acid to n-butanol conversion via syngas fermentation can be further improved. PMID:23172270

  10. Agent Architectures for Compliance

    NASA Astrophysics Data System (ADS)

    Burgemeestre, Brigitte; Hulstijn, Joris; Tan, Yao-Hua

    A Normative Multi-Agent System consists of autonomous agents who must comply with social norms. Different kinds of norms make different assumptions about the cognitive architecture of the agents. For example, a principle-based norm assumes that agents can reflect upon the consequences of their actions; a rule-based formulation only assumes that agents can avoid violations. In this paper we present several cognitive agent architectures for self-monitoring and compliance. We show how different assumptions about the cognitive architecture lead to different information needs when assessing compliance. The approach is validated with a case study of horizontal monitoring, an approach to corporate tax auditing recently introduced by the Dutch Customs and Tax Authority.

  11. Mitochondrial electron transfer chain complexes inhibition by different organochalcogens.

    PubMed

    Puntel, Robson L; Roos, Daniel H; Seeger, Rodrigo Lopes; Rocha, João B T

    2013-02-01

    Mitochondrial dysfunction plays a pivotal role in the cell toxicology and death decision. The aim of the present study was to investigate the effect of three organocompounds (ebselen [Ebs], diphenyl diselenide [(PhSe)(2)] and diphenyl ditelluride [(PhTe)(2)]) on mitochondrial complexes (I, II, I-III, II-III and IV) activity from rat liver and kidney to determine their potential role as molecular targets of organochalcogens. All studied organochalcogens caused a statistically significant inhibition of the mitochondrial complex I activity. Ebs and (PhTe)(2) caused a statistically significant inhibition of the mitochondrial complex II activity in both hepatic and renal membranes. Hepatic mitochondrial complex II activity was practically unchanged by (PhSe)(2), whereas it significantly inhibited renal complex II activity. Mitochondrial complex IV activity was practically unchanged by the organochalcogens. Furthermore, organochalcogens inhibited the mitochondrial respiration supported by complex I or complex II substrates. The inhibitory effect of Ebs, (PhSe)(2) and (PhTe)(2) on mitochondrial complex I was prevented by NADH, but it was not prevented by catalase (CAT) and/or superoxide dismutase (SOD). Additionally, the organochalcogens-induced inhibition of complex I and II was completely reversed by reduced glutathione (GSH). In conclusion, Ebs, (PhSe)(2) and (PhTe)(2) were more effective inhibitors of renal and hepatic mitochondrial complex I than complex II, whereas complexes III and IV were little modified by these compounds. Taking into account the presented results, we suggest that organochalcogen-induced mitochondrial complexes I and II inhibition can be mediated by their thiol oxidation activity, i.e., Ebs, (PhSe)(2) and (PhTe)(2) can oxidize critical thiol groups from mitochondrial complexes I and II. So, mitochondrial dysfunction can be considered an important factor in the toxicity of Ebs, (PhSe)(2) and (PhTe)(2). PMID:23103426

  12. Multi-Agent Patrolling under Uncertainty and Threats

    PubMed Central

    Chen, Shaofei; Wu, Feng; Shen, Lincheng; Chen, Jing; Ramchurn, Sarvapali D.

    2015-01-01

    We investigate a multi-agent patrolling problem where information is distributed alongside threats in environments with uncertainties. Specifically, the information and threat at each location are independently modelled as multi-state Markov chains, whose states are not observed until the location is visited by an agent. While agents will obtain information at a location, they may also suffer damage from the threat at that location. Therefore, the goal of the agents is to gather as much information as possible while mitigating the damage incurred. To address this challenge, we formulate the single-agent patrolling problem as a Partially Observable Markov Decision Process (POMDP) and propose a computationally efficient algorithm to solve this model. Building upon this, to compute patrols for multiple agents, the single-agent algorithm is extended for each agent with the aim of maximising its marginal contribution to the team. We empirically evaluate our algorithm on problems of multi-agent patrolling and show that it outperforms a baseline algorithm up to 44% for 10 agents and by 21% for 15 agents in large domains. PMID:26086946

  13. Chemical crowd control agents.

    PubMed

    Menezes, Ritesh G; Hussain, Syed Ather; Rameez, Mansoor Ali Merchant; Kharoshah, Magdy A; Madadin, Mohammed; Anwar, Naureen; Senthilkumaran, Subramanian

    2016-03-01

    Chemical crowd control agents are also referred to as riot control agents and are mainly used by civil authorities and government agencies to curtail civil disobedience gatherings or processions by large crowds. Common riot control agents used to disperse large numbers of individuals into smaller, less destructive, and more easily controllable numbers include chloroacetophenone, chlorobenzylidenemalononitrile, dibenzoxazepine, diphenylaminearsine, and oleoresin capsicum. In this paper, we discuss the emergency medical care needed by sufferers of acute chemical agent contamination and raise important issues concerning toxicology, safety and health. PMID:26658556

  14. Magnetocaloric effect in ferroelectric Ising chain magnet

    NASA Astrophysics Data System (ADS)

    Qi, Yan; Liu, Jia; Yu, Nai-sen; Du, An

    2016-05-01

    We investigate the magnetocaloric effect (MCE) in multiferroic chain system by adopting the elastic Ising-chain model. Based on the transfer-matrix method, the magnetothermal quantities of characterizing MCE behaviors including the entropy, entropy change and adiabatic cooling rate are rigorously determined. Combined with analysis of ground-state, we mainly discuss results in an antiferromagnetic regime associated with ferroelectric transition. Our results show that the entropy change is greatly enhanced near the saturation field as frustration parameter varies in this regime, and accompanied with remarkable inverse MCE, indicating the enormous potential of multiferroic system in low-temperature refrigeration. Meanwhile we also observe a prominent temperature variation in the isoentropy curves close to zero-temperature ferroelectric transition, but this enhancing MCE signal is very sensitive to the thermal fluctuations, and can be strongly suppressed even under a small temperature.

  15. Cross-contact chain

    NASA Technical Reports Server (NTRS)

    Lieneweg, Udo (Inventor)

    1988-01-01

    A system is provided for use with wafers that include multiple integrated circuits that include two conductive layers in contact at multiple interfaces. Contact chains are formed beside the integrated circuits, each contact chain formed of the same two layers as the circuits, in the form of conductive segments alternating between the upper and lower layers and with the ends of the segments connected in series through interfaces. A current source passes a current through the series-connected segments, by way of a pair of current tabs connected to opposite ends of the series of segments. While the current flows, voltage measurements are taken between each of a plurality of pairs of voltage tabs, the two tabs of each pair connected to opposite ends of an interface that lies along the series-connected segments. A plot of interface conductances on a normal probability chart, enables prediction of the yield of good integrated circuits from the wafer.

  16. Cross-contact chain

    NASA Technical Reports Server (NTRS)

    Lieneweg, U. (Inventor)

    1986-01-01

    A system is provided for use with wafers that include multiple integrated circuits that include two conductive layers in contact at multiple interfaces. Contact chains are formed beside the integrated circuits, each contact chain formed of the same two layers as the circuits, in the form of conductive segments alternating between the upper and lower layers and with the ends of the segments connected in series through interfaces. A current source passes a current through the series-connected segments, by way of a pair of current tabs connected to opposite ends of the series of segments. While the current flows, voltage measurements are taken between each of a plurality of pairs of voltage tabs, the two tabs of each pair connected to opposite ends of an interface that lies along the series-connected segments. A plot of interface conductances on normal probability chart enables prediction of the yield of good integrated circuits from the wafer.

  17. Synthesis of stable Au-PEG nanocomposite chains in a single step precursor free method and its formation mechanism and Di-electric behavior

    NASA Astrophysics Data System (ADS)

    Neogy, Rajesh Kumar; Nath, Rajib; Basu, Gautam; Raychaudhuri, Arup Kumar

    2011-03-01

    We report a simple and effective one step and one-pot synthesis of stable assembly of Au nanoparticles (diameter 8-10nm) into chains in an Ethylene Glycol medium(MEG), using only a solid metallic Au target and a pulsed excimer laser. No use any external precursor, reducing agent or surfactant so it is a chemistry free synthesis route. The Au-PEG nanocomposite chains (with unbroken lengths often more than few microns) formed in liquid medium are mechanically and thermally stable and can be transferred unchanged into a solid substrate which can span a large surface area. The nanochains show a broad optical absorption near to visible spectrum. Hybrid of Au nanochains and separated nanoparticles can also be formed using a proper choice of the laser fluence and MEG/DI water concentration. The Au-PEG nanocomposite chains in the medium shows enhanced low frequency dielectric constant & electrical conductivity. NMR shows that due to the formation of dimer/trimers of MEG molecules that formed by the ablation process, attach to the Au nanoparticles and facilitate the nanocomposite chain formation. DST is acknowledged for financial support.

  18. Streamlining the supply chain.

    PubMed

    Neumann, Lydon

    2003-07-01

    Effective management of the supply chain requires attention to: Product management--formulary development and maintenance, compliance, clinical involvement, standardization, and demand-matching. Sourcing and contracting--vendor consolidation, GPO portfolio management, price leveling, content management, and direct contracting Purchasing and payment-cycle--automatic placement, web enablement, centralization, evaluated receipts settlement, and invoice matching Inventory and distribution management--"unofficial" and "official" locations, vendor-managed inventory, automatic replenishment, and freight management. PMID:12866156

  19. Callisto Crater Chain Mosaic

    NASA Technical Reports Server (NTRS)

    1997-01-01

    This mosaic of three images shows an area within the Valhalla region on Jupiter's moon, Callisto. North is to the top of the mosaic and the Sun illuminates the surface from the left. The smallest details that can be discerned in this picture are knobs and small impact craters about 160 meters (175 yards) across. The mosaic covers an area approximately 45 kilometers (28 miles) across. It shows part of a prominent crater chain located on the northern part of the Valhalla ring structure.

    Crater chains can form from the impact of material ejected from large impacts (forming secondary chains) or by the impact of a fragmented projectile, perhaps similar to the Shoemaker-Levy 9 cometary impacts into Jupiter in July 1994. It is believed this crater chain was formed by the impact of a fragmented projectile. The images which form this mosaic were obtained by the solid state imaging system aboard NASA's Galileo spacecraft on Nov. 4, 1996 (Universal Time).

    Launched in October 1989, Galileo entered orbit around Jupiter on December 7, 1995. The spacecraft's mission is to conduct detailed studies of the giant planet, its largest moons and the Jovian magnetic environment. The Jet Propulsion Laboratory, Pasadena, CA manages the mission for NASA's Office of Space Science, Washington, DC.

    This image and other images and data received from Galileo are posted on the World Wide Web Galileo mission home page at http://galileo.jpl.nasa.gov. Background information and educational context for the images can be found at http:// www.jpl.nasa.gov/galileo/sepo.

  20. The innovation value chain.

    PubMed

    Hansen, Morten T; Birkinshaw, Julian

    2007-06-01

    The challenges of coming up with fresh ideas and realizing profits from them are different for every company. One firm may excel at finding good ideas but may have weak systems for bringing them to market. Another organization may have a terrific process for funding and rolling out new products and services but a shortage of concepts to develop. In this article, Hansen and Birkinshaw caution executives against using the latest and greatest innovation approaches and tools without understanding the unique deficiencies in their companies' innovation systems. They offer a framework for evaluating innovation performance: the innovation value chain. It comprises the three main phases of innovation (idea generation, conversion, and diffusion) as well as the critical activities performed during those phases (looking for ideas inside your unit; looking for them in other units; looking for them externally; selecting ideas; funding them; and promoting and spreading ideas companywide). Using this framework, managers get an end-to-end view of their innovation efforts. They can pinpoint their weakest links and tailor innovation best practices appropriately to strengthen those links. Companies typically succumb to one of three broad "weakest-link" scenarios. They are idea poor, conversion poor, or diffusion poor. The article looks at the ways smart companies - including Intuit, P&G, Sara Lee, Shell, and Siemens- modify the best innovation practices and apply them to address those organizations' individual needs and flaws. The authors warn that adopting the chain-based view of innovation requires new measures of what can be delivered by each link in the chain. The approach also entails new roles for employees "external scouts" and "internal evangelists," for example. Indeed, in their search for new hires, companies should seek out those candidates who can help address particular weaknesses in the innovation value chain. PMID:17580654

  1. Intermuscular force transmission along myofascial chains: a systematic review.

    PubMed

    Krause, Frieder; Wilke, Jan; Vogt, Lutz; Banzer, Winfried

    2016-06-01

    The present review aims to provide a systematic overview on tensile transmission along myofascial chains based on anatomical dissection studies and in vivo experiments. Evidence for the existence of myofascial chains is growing, and the capability of force transmission via myofascial chains has been hypothesized. However, there is still a lack of evidence concerning the functional significance and capability for force transfer. A systematic literature research was conducted using MEDLINE (Pubmed), ScienceDirect and Google Scholar. Studied myofascial chains encompassed the superficial backline (SBL), the back functional line (BFL) and the front functional line (FFL). Peer-reviewed human dissection studies as well as in vivo experiments reporting intermuscular tension transfer between the constituents of a myofascial chain were included. To assess methodic quality, two independent investigators rated studies by means of validated assessment tools (QUACS and PEDro Scale). The literature research identified 1022 articles. Nine studies (moderate to excellent methodological quality) were included. Concerning the SBL and the BFL, there is moderate evidence for force transfer at all three transitions (based on six studies), and one of two transitions (three studies). One study yields moderate evidence for a slight, but not significant force transfer at one transition in the FFL. The findings of the present study indicate that tension can be transferred between some of the examined adjacent structures. Force transfer might have an impact in overuse conditions as well as on sports performance. However, different methods of force application and measurement hinder the comparability of results. Considering anatomical variations in the degree of continuity and histological differences of the linking structures is crucial for interpretation. Future studies should focus on the in vivo function of myofascial continuity during isolated active or passive tissue tensioning. PMID

  2. Thermally multiplexed polymerase chain reaction

    PubMed Central

    Phaneuf, Christopher R.; Pak, Nikita; Saunders, D. Curtis; Holst, Gregory L.; Birjiniuk, Joav; Nagpal, Nikita; Culpepper, Stephen; Popler, Emily; Shane, Andi L.; Jerris, Robert; Forest, Craig R.

    2015-01-01

    Amplification of multiple unique genetic targets using the polymerase chain reaction (PCR) is commonly required in molecular biology laboratories. Such reactions are typically performed either serially or by multiplex PCR. Serial reactions are time consuming, and multiplex PCR, while powerful and widely used, can be prone to amplification bias, PCR drift, and primer-primer interactions. We present a new thermocycling method, termed thermal multiplexing, in which a single heat source is uniformly distributed and selectively modulated for independent temperature control of an array of PCR reactions. Thermal multiplexing allows amplification of multiple targets simultaneously—each reaction segregated and performed at optimal conditions. We demonstrate the method using a microfluidic system consisting of an infrared laser thermocycler, a polymer microchip featuring 1 μl, oil-encapsulated reactions, and closed-loop pulse-width modulation control. Heat transfer modeling is used to characterize thermal performance limitations of the system. We validate the model and perform two reactions simultaneously with widely varying annealing temperatures (48 °C and 68 °C), demonstrating excellent amplification. In addition, to demonstrate microfluidic infrared PCR using clinical specimens, we successfully amplified and detected both influenza A and B from human nasopharyngeal swabs. Thermal multiplexing is scalable and applicable to challenges such as pathogen detection where patients presenting non-specific symptoms need to be efficiently screened across a viral or bacterial panel. PMID:26339317

  3. Single-Chain Antibody Library

    DOE Data Explorer

    Baird, Cheryl

    Researchers at Pacific Northwest National Laboratory (PNNL) have constructed a nonimmune library consisting of 109 human antibody scFv fragments, which have been cloned and expressed on the surface of yeast. Nanomolar-affinity scFvs are routinely obtained by magnetic bead screening and flow cytometric sorting. The yeast library can be amplified 1010 fold without measurable loss of clonal diversity. This allows for indefinite expansion of the library. All scFv clones can be assessed directly on the yeast cell surface by immunofluorescent labeling and flow cytometry, obviating separate subcloning, expression, and purification steps. The ability to use multiplex library screening demonstrates the utility of this approach for high-throughput antibody isolation for proteomic applications. The yeast library may be used for research projects or teaching performed for U.S. Government purposes only. If you would like to request an aliquot of the single-chain antibody library for your research, please print and fill out the Materials Transfer Agreement (MTA) [PDF, 20K]. The website provides the contact information for mailing the MTA. [copied from http://www.sysbio.org/dataresources/singlechain.stm

  4. 42 CFR 73.6 - Exemptions for overlap select agents and toxins.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... days after identification, the select agent or toxin is transferred in accordance with § 73.16 or 9 CFR part 121.16 or destroyed on-site by a recognized sterilization or inactivation process, (2) The select... of receipt, the select agent or toxin is transferred in accordance with § 73.16 or 9 CFR part...

  5. 42 CFR 73.6 - Exemptions for overlap select agents and toxins.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... days after identification, the select agent or toxin is transferred in accordance with § 73.16 or 9 CFR part 121.16 or destroyed on-site by a recognized sterilization or inactivation process, (2) The select... of receipt, the select agent or toxin is transferred in accordance with § 73.16 or 9 CFR part...

  6. Application of rubber anti-aging agents in preventing coal spontaneous combustion

    SciTech Connect

    Yu, S.; Zhang, R.; Yang, Y.; Yang, H.; Fan, X.

    1999-07-01

    Based on the mechanism of rubber aging and action of anti-aging agents in preventing rubber aging, the free radical chain reaction mechanism of the oxidation of coal was discussed and compound stopping agents were introduced in the paper. The rubber anti-aging agents of aromatic amine are selected for the stopping agent of preventing coal spontaneous combustion. The stopping action of these anti-aging agents and common inorganic salt stopping agents for long flame coal in Gengcun Colliery, Yima city, Henan province in China is researched. The anti-aging agents for the long flame coal have the prominent efficiency and fine stopping action in later period, and inorganic stopping agents containing magnesium chloride salt for the long flame coal have the prominent efficiency in early period, but the compound stopping agents that are composed of the rubber anti-aging agents and magnesium chloride have longer life.

  7. Technology Transfer

    NASA Technical Reports Server (NTRS)

    Smith, Nanette R.

    1995-01-01

    The objective of this summer's work was to attempt to enhance Technology Application Group (TAG) ability to measure the outcomes of its efforts to transfer NASA technology. By reviewing existing literature, by explaining the economic principles involved in evaluating the economic impact of technology transfer, and by investigating the LaRC processes our William & Mary team has been able to lead this important discussion. In reviewing the existing literature, we identified many of the metrics that are currently being used in the area of technology transfer. Learning about the LaRC technology transfer processes and the metrics currently used to track the transfer process enabled us to compare other R&D facilities to LaRC. We discuss and diagram impacts of technology transfer in the short run and the long run. Significantly, it serves as the basis for analysis and provides guidance in thinking about what the measurement objectives ought to be. By focusing on the SBIR Program, valuable information regarding the strengths and weaknesses of this LaRC program are to be gained. A survey was developed to ask probing questions regarding SBIR contractors' experience with the program. Specifically we are interested in finding out whether the SBIR Program is accomplishing its mission, if the SBIR companies are providing the needed innovations specified by NASA and to what extent those innovations have led to commercial success. We also developed a survey to ask COTR's, who are NASA employees acting as technical advisors to the SBIR contractors, the same type of questions, evaluating the successes and problems with the SBIR Program as they see it. This survey was developed to be implemented interactively on computer. It is our hope that the statistical and econometric studies that can be done on the data collected from all of these sources will provide insight regarding the direction to take in developing systematic evaluations of programs like the SBIR Program so that they can

  8. Change Agent Survival Guide

    ERIC Educational Resources Information Center

    Dunbar, Folwell L.

    2011-01-01

    Consulting is a rough racket. Only a tarantula hair above IRS agents, meter maids and used car sales people, the profession is a prickly burr for slings and arrows. Throw in education, focus on dysfunctional schools and call oneself a "change agent," and this bad rap all but disappears. Unfortunately, though, consulting/coaching/mentoring in…

  9. Travel Agent Course Outline.

    ERIC Educational Resources Information Center

    British Columbia Dept. of Education, Victoria.

    Written for college entry-level travel agent training courses, this course outline can also be used for inservice training programs offered by travel agencies. The outline provides information on the work of a travel agent and gives clear statements on what learners must be able to do by the end of their training. Material is divided into eight…

  10. Alpha chain unsaturated derivatives of misoprostol.

    PubMed

    Collins, P W; Gasiecki, A F; Weier, R M; Kramer, S W; Jones, P H; Gullikson, G W; Bianchi, R G; Bauer, R F

    1987-01-01

    Misoprostol, a 15-deoxy-16-hydroxy-16-methyl analog of PGE1, is an effective agent for the treatment of peptic ulcer disease. Efforts to impede metabolic degradation of the alpha chain of misoprostol led to the discovery of a second clinical candidate in this series. Enisoprost, a delta 4Z derivative of misoprostol, is more potent as a gastric antisecretory agent and longer acting than misoprostol. These findings prompted further work to determine the effects that two double bonds in the alpha chain might have on the activity profile of misoprostol. The most promising structure in this series was a 1:1 mixture of 3E,5Z and 3Z,5Z dienes which was about three times more potent than misoprostol in inhibiting gastric secretion in dogs, while the separation of the diarrheogenic effect was significantly improved. Chromatographic separation of the mixture was very difficult, but small amounts of each isomer were obtained by HPLC, and preliminary antisecretory studies indicated that most of the activity resided in the 3E,5Z isomer. A stereospecific synthesis of the 3E,5Z isomer was carried out to provide sufficient quantities for complete pharmacological assessment. The 3E,5Z diene was about three times more potent than misoprostol in inhibiting gastric acid secretion in dogs and also in producing diarrhea in rats. PMID:3122273

  11. Pediatric Antifungal Agents

    PubMed Central

    Cohen-Wolkowiez, Michael; Moran, Cassandra; Benjamin, Daniel K.; Smith, P Brian

    2009-01-01

    Purpose of review In immunocompromised hosts, invasive fungal infections are common and fatal. In the past decade, the antifungal armamentarium against invasive mycoses has expanded greatly. The purpose of this report is to review the most recent literature addressing the use of antifungal agents in children. Recent findings Most studies evaluating the safety and efficacy of antifungal agents are limited to adults. However, important progress has been made in describing the pharmacokinetics and safety of newer antifungal agents in children, including the echinocandins. Summary Dosage guidelines for newer antifungal agents are currently based on adult and limited pediatric data. Because important developmental pharmacology changes occur throughout childhood impacting the pharmacokinetics of these agents, antifungal studies specifically designed for children are necessary. PMID:19741525

  12. How do agents represent?

    NASA Astrophysics Data System (ADS)

    Ryan, Alex

    Representation is inherent to the concept of an agent, but its importance in complex systems has not yet been widely recognised. In this paper I introduce Peirce's theory of signs, which facilitates a definition of representation in general. In summary, representation means that for some agent, a model is used to stand in for another entity in a way that shapes the behaviour of the agent with respect to that entity. Representation in general is then related to the theories of representation that have developed within different disciplines. I compare theories of representation from metaphysics, military theory and systems theory. Additional complications arise in explaining the special case of mental representations, which is the focus of cognitive science. I consider the dominant theory of cognition — that the brain is a representational device — as well as the sceptical anti-representational response. Finally, I argue that representation distinguishes agents from non-representational objects: agents are objects capable of representation.

  13. Standard Agent Framework 1

    Energy Science and Technology Software Center (ESTSC)

    1999-04-06

    The Standard Agent framework provides an extensible object-oriented development environment suitable for use in both research and applications projects. The SAF provides a means for constructing and customizing multi-agent systems through specialization of standard base classes (architecture-driven framework) and by composition of component classes (data driven framework). The standard agent system is implemented as an extensible object-centerd framework. Four concrete base classes are developed: (1) Standard Agency; (2) Standard Agent; (3) Human Factor, and (4)more » Resources. The object-centered framework developed and utilized provides the best comprimise between generality and flexibility available in agent development systems today.« less

  14. CHI: A General Agent Communication Framework

    SciTech Connect

    Goldsmith, S.Y.; Phillips, L.R.; Spires, S.V.

    1998-12-17

    We have completed and exercised a communication framework called CHI (CLOS to HTML Interface) by which agents can communicate with humans. CHI follows HTTP (HyperText Transfer Protocol) and produces HTML (HyperText Markup Language) for use by WWW (World-Wide Web) browsers. CHI enables the rapid and dynamic construction of interface mechanisms. The essence of CHI is automatic registration of dynamically generated interface elements to named objects in the agent's internal environment. The agent can access information in these objects at will. State is preserved, so an agent can pursue branching interaction sequences, activate failure recovery behaviors, and otherwise act opportunistically to maintain a conversation. The CHI mechanism remains transparent in multi-agent, multi-user environments because of automatically generated unique identifiers built into the CHI mechanism. In this paper we discuss design, language, implementation, and extension issues, and, by way of illustration, examine the use of the general CHI/HCHI mechanism in a specific international electronic commerce system. We conclude that the CHI mechanism is an effective, efficient, and extensible means of the agent/human communication.

  15. Requirements of supply chain management in differentiating European pork chains.

    PubMed

    Trienekens, Jacques; Wognum, Nel

    2013-11-01

    This paper summarizes results obtained by research into pork chain management in the EU Integrated Project Q-Porkchains. Changing demands for intrinsic and extrinsic quality attributes of pork products impact the way supply chain management should be organized from the farmer down to the consumer. The paper shows the importance of Quality Management Systems for integrating supply chains and enhancing consumer confidence. The paper also presents innovations in information system integration for aligning information exchange in the supply chain and logistics concepts based on innovative measurement technologies at the slaughterhouse stage. In the final section research challenges towards sustainable pork supply chains satisfying current consumer demands are presented. PMID:23611335

  16. Hyperinflation in the Ising model on quasiperiodic chains

    NASA Astrophysics Data System (ADS)

    Odagaki, T.

    1990-02-01

    Using a hyperinflation rule, the free energy of the two component Ising system on a chain with an arbitrary quasiperiodic order is shown to be given by an average of the free energy of each component, in agreement with the result obtained by the transfer matrix formalism.

  17. [Technology Transfer.

    ERIC Educational Resources Information Center

    Latker, Norman J.

    Some authorities on technolgoy transfer feel that industry is not fully capitalizing on the inventive output of universities and nonprofit organizations. From the point of view of the government, the stakes are high. The magnitude of federal support of research and development in these organizations demands evidence of useful results if it is to…

  18. A Framework of Multi Objectives Negotiation for Dynamic Supply Chain Model

    NASA Astrophysics Data System (ADS)

    Chai, Jia Yee; Sakaguchi, Tatsuhiko; Shirase, Keiichi

    Trends of globalization and advances in Information Technology (IT) have created opportunity in collaborative manufacturing across national borders. A dynamic supply chain utilizes these advances to enable more flexibility in business cooperation. This research proposes a concurrent decision making framework for a three echelons dynamic supply chain model. The dynamic supply chain is formed by autonomous negotiation among agents based on multi agents approach. Instead of generating negotiation aspects (such as amount, price and due date) arbitrary, this framework proposes to utilize the information available at operational level of an organization in order to generate realistic negotiation aspect. The effectiveness of the proposed model is demonstrated by various case studies.

  19. 9 CFR 121.6 - Exemptions for overlap select agents and toxins.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... CFR 73.16 or destroyed on-site by a recognized sterilization or inactivation process; (2) The agent or... after identification, the agent or toxin is transferred in accordance with § 121.16 or 42 CFR 73.16 or destroyed on-site by a recognized sterilization or inactivation process; (2) The agent or toxin is...

  20. [Light Chain Amyloidosis: an Update for Treatment].

    PubMed

    Shen, Kai-Ni; Li, Jian

    2015-06-01

    Systemic light chain amyloidosis (AL amyloidosis) is the most common type of amyloidosis, in which deposition of misfolded monoclonal light chain secreted by underlying clonal plasma cells leads to organ dysfunction. Tissue biopsy of involved organ is needed to confirm the type of amyloid deposits, thus proper treatment could be applied. Laser microdissection followed by mass spectrometry, performed on formalin-fixed paraffin-embedded specimens, has been proven superior to traditional methods on accurate diagnosis of amyloidosis. Prognosis depends on the extent of cardiac involvement. The Mayo staging system using NT-ProBNP, cardiac troponin-T and free light chain, is the most robust method for risk stratification and treatment guidance. The introduction of autologous stem cell transplantation (auto-ASCT) resulted in long-term survival in responders, while treatment-related toxicity substantially limited the number of eligible candidates. Novel agents, especially bortezomib, thalidomide and lenalidomide hold promise to achieve comparable hematological responses with auto-ASCT, which might play significant role in treatment of recurrent or refractory AL amyloidosis. PMID:26117060

  1. Radiology's value chain.

    PubMed

    Enzmann, Dieter R

    2012-04-01

    A diagnostic radiology value chain is constructed to define its main components, all of which are vulnerable to change, because digitization has caused disaggregation of the chain. Some components afford opportunities to improve productivity, some add value, while some face outsourcing to lower labor cost and to information technology substitutes, raising commoditization risks. Digital image information, because it can be competitive at smaller economies of scale, allows faster, differential rates of technological innovation of components, initiating a centralization-to-decentralization technology trend. Digitization, having triggered disaggregation of radiology's professional service model, may soon usher in an information business model. This means moving from a mind-set of "reading images" to an orientation of creating and organizing information for greater accuracy, faster speed, and lower cost in medical decision making. Information businesses view value chain investments differently than do small professional services. In the former model, producing a better business product will extend image interpretation beyond a radiologist's personal fund of knowledge to encompass expanding external imaging databases. A follow-on expansion with integration of image and molecular information into a report will offer new value in medical decision making. Improved interpretation plus new integration will enrich and diversify radiology's key service products, the report and consultation. A more robust, information-rich report derived from a "systems" and "computational" radiology approach will be facilitated by a transition from a professional service to an information business. Under health care reform, radiology will transition its emphasis from volume to greater value. Radiology's future brightens with the adoption of a philosophy of offering information rather than "reads" for decision making. Staunchly defending the status quo via turf wars is unlikely to constitute a

  2. The causal agents of damping-off disease of buglosse from Iran.

    PubMed

    Okhovvat, S M; Zakeri, Z; Moshashai, R

    2005-01-01

    Iran is considered a major genetic for medicinal plant in the world. Because of this significant diversity and historical background in identification and utilization to remedy human and animal diseases, export of medicinal plant can help to strengthen local as well as natural economy. Buglosse (Fig. 1) is one of the most important and common medicinal plants in Iran and exist as Echium amoneum and Borago officinalis. This work was conducted in order to identify the causal agent(s) of damping off disease in buglosse. Plant disease samples were taken from Esfahan and Tehran provinces. Symptoms on original plant including root, crown rot, dark tissue, pith and hallow root were collected in order to isolate disease agent(s). Symptomatic root and crown tissues after surface sterilization with 96% ethanol were transferred on to PDA and WA media and also on moist filter paper in petri dishes. Two fungal colonies grew from tissue segments and spore culture was subsequently purified. The fungal isolate identified as Rhizoctonia solani based on the following test. Hyphal tip was removed from colony margin placed on PDA and PSA media and incubated in dark. Colony diameter of one hundred hyphae measured and nucleus was stained according to Bandoni (1979), Kronland and Stanghellini (1988). It was observed that in each cell of hyphae there are more than two nuclei. Single spore culture were obtained from macroconidia of Fusarium isolate. After 24 hr of incubation, growing single spore were transferred to KCL medium to detect spore chains. Fungal isolates transferred to PSA and PDA media for sporulation. After 7 days colonies appeared as white cream to pinkish on top and cream to dark pink at the bottom of petri dish with abundant micro and macro conidia. Colonies were snow white, felting shape, with ample causal hyphae on PSA medium. On KCL medium, fungal growth was superficial and colonies were colorless with long macroconidia and individual sausage-shape macroconidia being

  3. Musical Markov Chains

    NASA Astrophysics Data System (ADS)

    Volchenkov, Dima; Dawin, Jean René

    A system for using dice to compose music randomly is known as the musical dice game. The discrete time MIDI models of 804 pieces of classical music written by 29 composers have been encoded into the transition matrices and studied by Markov chains. Contrary to human languages, entropy dominates over redundancy, in the musical dice games based on the compositions of classical music. The maximum complexity is achieved on the blocks consisting of just a few notes (8 notes, for the musical dice games generated over Bach's compositions). First passage times to notes can be used to resolve tonality and feature a composer.

  4. Monte Carlo without chains

    SciTech Connect

    Chorin, Alexandre J.

    2007-12-12

    A sampling method for spin systems is presented. The spin lattice is written as the union of a nested sequence of sublattices, all but the last with conditionally independent spins, which are sampled in succession using their marginals. The marginals are computed concurrently by a fast algorithm; errors in the evaluation of the marginals are offset by weights. There are no Markov chains and each sample is independent of the previous ones; the cost of a sample is proportional to the number of spins (but the number of samples needed for good statistics may grow with array size). The examples include the Edwards-Anderson spin glass in three dimensions.

  5. Biological warfare agents

    PubMed Central

    Thavaselvam, Duraipandian; Vijayaraghavan, Rajagopalan

    2010-01-01

    The recent bioterrorist attacks using anthrax spores have emphasized the need to detect and decontaminate critical facilities in the shortest possible time. There has been a remarkable progress in the detection, protection and decontamination of biological warfare agents as many instrumentation platforms and detection methodologies are developed and commissioned. Even then the threat of biological warfare agents and their use in bioterrorist attacks still remain a leading cause of global concern. Furthermore in the past decade there have been threats due to the emerging new diseases and also the re-emergence of old diseases and development of antimicrobial resistance and spread to new geographical regions. The preparedness against these agents need complete knowledge about the disease, better research and training facilities, diagnostic facilities and improved public health system. This review on the biological warfare agents will provide information on the biological warfare agents, their mode of transmission and spread and also the detection systems available to detect them. In addition the current information on the availability of commercially available and developing technologies against biological warfare agents has also been discussed. The risk that arise due to the use of these agents in warfare or bioterrorism related scenario can be mitigated with the availability of improved detection technologies. PMID:21829313

  6. Dioxin, agent orange

    SciTech Connect

    Gough, M.

    1986-01-01

    This book presents information on the following topics: dioxin, a prevalent problem; nobody wanted dioxin; agent organe and Vietnam; what we know about and may learn about agent orange and Veterans' health; agent organe and birth defects; dioxin in Missouri; 2, 4, 5-T: the U.S.' disappearing herbicide; Seveso: high-level environmental exposure; the nitro explosion; industrial exposures to dioxin; company behavior in the face of dioxin exposures; dioxin and specific cancers; animal tests of dioxin toxicity; dioxin decions; the present and the future.

  7. Rural Child Labour: Views of Extension Agents in Ethiopia

    ERIC Educational Resources Information Center

    Murray, Una

    2013-01-01

    Purpose: Whilst children working in agriculture and domestic work is an inherent part of growing up and essential for survival, if boys and girls lose out on education they are less equipped to respond to inevitable environmental shocks and to negotiate agri-food value chains. This article investigates views of extension agents on children…

  8. [Trophic chains in soil].

    PubMed

    2013-01-01

    Trophic links of soil animals are extensively diverse but also flexible. Moreover, feeding activity of large soil saprotrophs often cascades into a range of ecosystem-level consequences via the ecological engineering. Better knowledge on the main sources of energy utilized by soil animals is needed for understanding functional structure of soil animal communities and their participation in the global carbon cycling. Using published and original data, we consider the relative importance of dead organic matter and saprotrophic microorganisms as a basal energy source in the detritus-based food chains, the feeding of endogeic macrofauna on the stabilized soil organic matter, and the role of recent photosynthate in the energy budget of soil communities. Soil food webs are spatially and functionally compartmentalized, though the separation of food chains into bacteria- and fungi-based channels seems to be an over-simplification. The regulation of the litter decomposition rates via top-down trophic interactions across more than one trophic level is only partly supported by experimental data, but mobile litter-dwelling predators play a crucial role in integrating local food webs within and across neighboring ecosystems. PMID:25508107

  9. [Trophic chains in soil].

    PubMed

    Goncharov, A A; Tiunov, A V

    2013-01-01

    Trophic links of soil animals are extensively diverse but also flexible. Moreover, feeding activity of large soil saprotrophs often cascades into a range of ecosystem-level consequences via the ecological engineering. Better knowledge on the main sources of energy utilized by soil animals is needed for understanding functional structure of soil animal communities and their participation in the global carbon cycling. Using published and original data, we consider the relative importance of dead organic matter and saprotrophic microorganisms as a basal energy source in the detritus-based food chains, the feeding of endogeic macrofauna on the stabilized soil organic matter, and the role of recent photosynthate in the energy budget of soil communities. Soil food webs are spatially and functionally compartmentalized, though the separation of food chains into bacteria- and fungi-based channels seems to be an over-simplification. The regulation of the litter decomposition rates via top-down trophic interactions across more than one trophic level is only partly supported by experimental data, but mobile litter-dwelling predators play a crucial role in integrating local food webs within and across neighboring ecosystems. PMID:25438576

  10. Analysis of a complex shape chain plate using Transmission Photoelasticity

    NASA Astrophysics Data System (ADS)

    Dasari, N.; Ramesh, K.

    2010-06-01

    Most chains are an assembly [1] of five parts namely, outer plate, inner plate, bush, pin and roller. Two inner plates are press fitted with two bushes to form an inner block assembly. The outer plates are press fitted with pins after keeping the pins through the assembled bushes of the inner block. Roller is a rotating member and placed over the bush during inner block assembly. Inner block assembly is the load transfer member from sprocket tooth. The outer block assembly helps in holding and also to pull the inner block over the sprocket teeth. If a chain length is in odd number of pitches, it requires an offset plate as shown in Figure 1 to connect two ends of the chain together to make chain endless. When the chain is assembled with an offset plate, the chain fatigue life was observed only 20 to 25% of the total life of a chain, assembled without an offset plate. The holes in the offset plate are of the same size as in the outer and inner plates respectively and it is a complex in shape chain plate. A inbuilt thinning zone at the centre of the chain plate as shown in Figure 1 is unavoidable. The stresses and its distribution in this complex shape chain plate geometry play a critical role in the fatigue life performance of a chain assembly. However, it is difficult identify the stress distribution and stress concentration zones precisely using only the conventional industrial friendly tools such as routine quality control test, breaking load test and numerical computations. In this context the transmission photoelastic technique has made it possible to identify the stress distribution, its concentration and also to quantify the stress and strain [2-3] at any point in the chain plate. This paper explains how transmission photoelastic technique is used to estimate the stress distribution and its concentration zones in a complex chain plate when it isloaded. An epoxy chain plate model was made through the casting method using a Perspex mould [2-3]. A loading

  11. Transfer functions

    NASA Technical Reports Server (NTRS)

    Taback, I.

    1979-01-01

    The vulnerability of electronic equipment to carbon fibers is studied. The effectiveness of interfaces, such as filters, doors, window screens, and cabinets, which affect the concentration, exposure, or deposition of carbon fibers on both (internal and external) sides of the interface is examined. The transfer function of multilayer aluminum mesh, wet and dry, polyurethane foam, and window screen are determined as a function of air velocity. FIlters installed in typical traffic control boxes and air conditioners are also considered.

  12. Agent oriented programming

    NASA Technical Reports Server (NTRS)

    Shoham, Yoav

    1994-01-01

    The goal of our research is a methodology for creating robust software in distributed and dynamic environments. The approach taken is to endow software objects with explicit information about one another, to have them interact through a commitment mechanism, and to equip them with a speech-acty communication language. System-level applications include software interoperation and compositionality. A government application of specific interest is an infrastructure for coordination among multiple planners. Daily activity applications include personal software assistants, such as programmable email, scheduling, and new group agents. Research topics include definition of mental state of agents, design of agent languages as well as interpreters for those languages, and mechanisms for coordination within agent societies such as artificial social laws and conventions.

  13. Radioactive diagnostic agent

    SciTech Connect

    Shigematsu, A.; Aihara, M.; Matsuda, M.; Suzuki, A.; Tsuya, A.

    1984-02-07

    A radioactive diagnostic agent for renal cortex, adrenal cortex, myocardium, brain stem, spinal nerve, etc., which comprises as an essential component monoiodoacetic acid wherein the iodine atom is radioactive.

  14. Riot Control Agents

    MedlinePlus

    ... your clothing, rapidly wash your entire body with soap and water, and get medical care as quickly ... agent from your skin with large amounts of soap and water. Washing with soap and water will ...

  15. Dual chain synthetic heparin-binding growth factor analogs

    DOEpatents

    Zamora, Paul O.; Pena, Louis A.; Lin, Xinhua

    2012-04-24

    The invention provides synthetic heparin-binding growth factor analogs having two peptide chains each branched from a branch moiety, such as trifunctional amino acid residues, the branch moieties separated by a first linker of from 3 to about 20 backbone atoms, which peptide chains bind a heparin-binding growth factor receptor and are covalently bound to a non-signaling peptide that includes a heparin-binding domain, preferably by a second linker, which may be a hydrophobic second linker. The synthetic heparin-binding growth factor analogs are useful as pharmaceutical agents, soluble biologics or as surface coatings for medical devices.

  16. Dual chain synthetic heparin-binding growth factor analogs

    DOEpatents

    Zamora, Paul O.; Pena, Louis A.; Lin, Xinhua

    2009-10-06

    The invention provides synthetic heparin-binding growth factor analogs having two peptide chains each branched from a branch moiety, such as trifunctional amino acid residues, the branch moieties separated by a first linker of from 3 to about 20 backbone atoms, which peptide chains bind a heparin-binding growth factor receptor and are covalently bound to a non-signaling peptide that includes a heparin-binding domain, preferably by a second linker, which may be a hydrophobic second linker. The synthetic heparin-binding growth factor analogs are useful as pharmaceutical agents, soluble biologics or as surface coatings for medical devices.

  17. Analogs of the antituberculous agent pyrazinamide are competitive inhibitors of NADPH binding to M. tuberculosis fatty acid synthase I.

    PubMed

    Sayahi, Halimah; Pugliese, Kaitlin M; Zimhony, Oren; Jacobs, William R; Shekhtman, Alexander; Welch, John T

    2012-11-01

    Analogs of pyrazinamide (=pyrazine-2-carboxamide; PZA), an essential component of short-course antituberculous chemotherapy, such as 5-chloropyrazinamide (5-Cl-PZA) act as competitive inhibitors of NADPH binding to purified mycobacterial fatty acid synthase I (FAS I) as shown by Saturation Transfer Difference (STD) NMR studies. In addition, pyrazinoic acid esters (POE) and 5-Cl-POE reversibly bind to FAS I with the relatively greater affinity of longer-chain esters for FAS I, clear from the STD amplification factors. The competitive binding of PZA and 5-Cl-PZA clearly illustrates that both agents bind FAS. In contrast to PZA, at low NADPH concentrations 5-Cl-PZA is a cooperative inhibitor of NADPH binding. PMID:23161636

  18. Excited state proton transfer in 9-aminoacridine carboxamides in water and in DNA

    SciTech Connect

    Smith, C.A.

    1995-11-01

    The 9-aminoacridine molecule is important in several different fields of chemistry. The absorption and fluorescence spectra of this compound are pH sensitive and it is this property that allowed it to be used as a pH probe in different chemical environments. The compound exhibits proton transfer reactions which are among the most fundamental of chemical reactions. The planarity of 9-aminoacridine allows it to intercalate into DNA. Intercalation is a process in which the aromatic flat surface of the intercalator inserts between adjacent base pairs of DNA. The large surface area of 9-aminoacridine`s fused tricyclic ring system allows strong intercalative binding through van der Waals attractions. 9-aminoacridine and many of its derivatives have been tried as possible antitumor drugs. The cytotoxicity of an antitumor agent can be dramatically increased through the addition of one or two cationic side chains. This increase in cytotoxicity using the 9-aminoacridine compound as a parent molecule has been investigated through various derivatives with cationic side chains consisting of different number of carbon atoms between the proximal and distal N atoms. Similar derivatives varied the position of the carboxamide side chain on the aromatic ring system. The objective of this work is to first create a baseline study of the excited state kinetics of the 9-aminoacridine carboxamides in the absence of DNA. The baseline study will allow the excited state kinetics of these antitumor drugs when placed in DNA to be more fully understood.

  19. Synthesis and in vivo magnetic resonance imaging evaluation of biocompatible branched copolymer nanocontrast agents.

    PubMed

    Jackson, Alexander W; Chandrasekharan, Prashant; Shi, Jian; Rannard, Steven P; Liu, Quan; Yang, Chang-Tong; He, Tao

    2015-01-01

    Branched copolymer nanoparticles (D(h) =20-35 nm) possessing 1,4,7, 10-tetraazacyclododecane-N,N',N″,N‴-tetraacetic acid macrocycles within their cores have been synthesized and applied as magnetic resonance imaging (MRI) nanosized contrast agents in vivo. These nanoparticles have been generated from novel functional monomers via reversible addition-fragmentation chain transfer polymerization. The process is very robust and synthetically straightforward. Chelation with gadolinium and preliminary in vivo experiments have demonstrated promising characteristics as MRI contrast agents with prolonged blood retention time, good biocompatibility, and an intravascular distribution. The ability of these nanoparticles to perfuse and passively target tumor cells through the enhanced permeability and retention effect is also demonstrated. These novel highly functional nanoparticle platforms have succinimidyl ester-activated benzoate functionalities within their corona, which make them suitable for future peptide conjugation and subsequent active cell-targeted MRI or the conjugation of fluorophores for bimodal imaging. We have also demonstrated that these branched copolymer nanoparticles are able to noncovalently encapsulate hydrophobic guest molecules, which could allow simultaneous bioimaging and drug delivery. PMID:26425088

  20. Synthesis and in vivo magnetic resonance imaging evaluation of biocompatible branched copolymer nanocontrast agents

    PubMed Central

    Jackson, Alexander W; Chandrasekharan, Prashant; Shi, Jian; Rannard, Steven P; Liu, Quan; Yang, Chang-Tong; He, Tao

    2015-01-01

    Branched copolymer nanoparticles (Dh =20–35 nm) possessing 1,4,7, 10-tetraazacyclododecane-N,N′,N″,N‴-tetraacetic acid macrocycles within their cores have been synthesized and applied as magnetic resonance imaging (MRI) nanosized contrast agents in vivo. These nanoparticles have been generated from novel functional monomers via reversible addition–fragmentation chain transfer polymerization. The process is very robust and synthetically straightforward. Chelation with gadolinium and preliminary in vivo experiments have demonstrated promising characteristics as MRI contrast agents with prolonged blood retention time, good biocompatibility, and an intravascular distribution. The ability of these nanoparticles to perfuse and passively target tumor cells through the enhanced permeability and retention effect is also demonstrated. These novel highly functional nanoparticle platforms have succinimidyl ester-activated benzoate functionalities within their corona, which make them suitable for future peptide conjugation and subsequent active cell-targeted MRI or the conjugation of fluorophores for bimodal imaging. We have also demonstrated that these branched copolymer nanoparticles are able to noncovalently encapsulate hydrophobic guest molecules, which could allow simultaneous bioimaging and drug delivery. PMID:26425088

  1. Stable, Electroinactive Wetting Agent For Fuel Cells

    NASA Technical Reports Server (NTRS)

    Prakash, Surya G.; Olah, George A.; Narayanan, Sekharipuram R.; Surampudi, Subbarao; Halpert, Gerald

    1994-01-01

    Straight-chain perfluorooctanesulfonic acid (C8 acid) identified as innocuous and stable wetting agent for use with polytetrafluoroethylene-containing electrodes in liquid-feed direct-oxidation fuel cells suggested for use in vehicles and portable power supplies. C8 acid in small concentrations in aqueous liquid solutions of methanol, trimethoxymethane, dimethoxymethane, and trioxane enables oxidation of these substances by use of commercially available electrodes of type designed originally for use with gases. This function specific to C8 acid molecule and not achieved by other related perfluorolkanesulfonic acids.

  2. Doping of Semiconducting Atomic Chains

    NASA Technical Reports Server (NTRS)

    Toshishige, Yamada; Kutler, Paul (Technical Monitor)

    1997-01-01

    Due to the rapid progress in atom manipulation technology, atomic chain electronics would not be a dream, where foreign atoms are placed on a substrate to form a chain, and its electronic properties are designed by controlling the lattice constant d. It has been shown theoretically that a Si atomic chain is metallic regardless of d and that a Mg atomic chain is semiconducting or insulating with a band gap modified with d. For electronic applications, it is essential to establish a method to dope a semiconducting chain, which is to control the Fermi energy position without altering the original band structure. If we replace some of the chain atoms with dopant atoms randomly, the electrons will see random potential along the chain and will be localized strongly in space (Anderson localization). However, if we replace periodically, although the electrons can spread over the chain, there will generally appear new bands and band gaps reflecting the new periodicity of dopant atoms. This will change the original band structure significantly. In order to overcome this dilemma, we may place a dopant atom beside the chain at every N lattice periods (N > 1). Because of the periodic arrangement of dopant atoms, we can avoid the unwanted Anderson localization. Moreover, since the dopant atoms do not constitute the chain, the overlap interaction between them is minimized, and the band structure modification can be made smallest. Some tight-binding results will be discussed to demonstrate the present idea.

  3. Myosin light-chain phosphatase.

    PubMed Central

    Morgan, M; Perry, S V; Ottaway, J

    1976-01-01

    1. A method for the isolation of a new enzyme, myosin light-chain phosphatase, from rabbit white skeletal muscle by using a Sepharose-phosphorylated myosin light-chain affinity column is described. 2. The enzyme migrated as a single component on electrophoresis in sodium dodecyl sulphate/polyacrylamide gel at pH7.0, with apparent mol.wt. 70000. 3. The enzyme was highly specific for the phosphorylated P-light chain of myosin, had pH optima at 6.5 and 8.0 and was not inhibited by NaF. 4. A Ca2+-sensitive 'ATPase' (adenosine triphosphatase) system consisting of myosin light-chain kinase, myosin light-chain phosphatase and the P-light chain is described. 5. Evidence is presented for a phosphoryl exchange between Pi, phosphorylated P-light chain and myosin light-chain phosphatase. 6. Heavy meromyosin prepared by chymotryptic digestion can be phosphorylated by myosin light-chain kinase. 7. The ATPase activities of myosin and heavy meromyosin, in the presence and absence of F-actin, were not significantly changed (+/- 10%) by phosphorylation of the P-light chain. Images PLATE 1 PMID:186030

  4. Polymeric Thioxanthones as Potential Anticancer and Radiotherapy Agents.

    PubMed

    Yilmaz, Gorkem; Guler, Emine; Barlas, Firat Baris; Timur, Suna; Yagci, Yusuf

    2016-07-01

    Thioxanthone (TX) and its derivatives, which are widely used as photoinitiators in UV curing technology, hold promising research interest in biological applications. In particular, the use of TXs as anticancer agent has recently been manifested as an outstanding additional property of this class of molecules. Incorporation of TX molecules into specially designed polymers widens their practical use in such applications. In this study, two water-soluble, biocompatible, and stable polymers, namely poly(vinyl alcohol) and poly(ethylene glycol), possessing TX moieties at the side chains and chain ends, respectively, are prepared and used as anticancer and radiotherapy agents. The findings confirm that both polymers are potential candidates for therapeutic agents as they possess useful features including water-solubility, radiosensitizer effect, and anticancer activity in a polymeric scaffold. PMID:27168378

  5. Biodegradable Iodinated Polydisulfides as Contrast Agents for CT Angiography

    PubMed Central

    Jin, Erlei; Zheng-Rong, Lu

    2014-01-01

    Current clinical CT contrast agents are mainly small molecular iodinated compounds, which often suffer from short blood pool retention for more comprehensive cardiovascular CT imaging and may cause contrast-induced nephropathy. In this work, we prepared polydisulfides containing a traditional iodinated CT contrast agent in order to optimize the pharmacokinetics of the agent and improve its safety. Initially acting as a macromolecular agent and achieving sharp blood vessel delineation, the polydisulfides can be reduced by endogenous thiols via disulfide-thiol exchange reaction to oligomers that can be readily excreted via renal filtration. Short polyethylene glycol (PEG) chain was also introduced to the polymers to further modify the in vivo properties of the agents. Strong and prolonged vascular enhancement has been generated with two new agents in mice (5–10 times higher blood pool enhancement than iodinaxol). The polydisulfide agents gradually degraded and excreted via renal filtration. The gradual excretion process could prevent contrast induced nephropathy. These results suggest that the biodegradable macromolecular CT contrast agents are promising safe and effective blood contrast agents for CT angiography and image-guided interventions. PMID:24768156

  6. NNSA TRITIUM SUPPLY CHAIN

    SciTech Connect

    Wyrick, Steven; Cordaro, Joseph; Founds, Nanette; Chambellan, Curtis

    2013-08-21

    Savannah River Site plays a critical role in the Tritium Production Supply Chain for the National Nuclear Security Administration (NNSA). The entire process includes: • Production of Tritium Producing Burnable Absorber Rods (TPBARs) at the Westinghouse WesDyne Nuclear Fuels Plant in Columbia, South Carolina • Production of unobligated Low Enriched Uranium (LEU) at the United States Enrichment Corporation (USEC) in Portsmouth, Ohio • Irradiation of TPBARs with the LEU at the Tennessee Valley Authority (TVA) Watts Bar Reactor • Extraction of tritium from the irradiated TPBARs at the Tritium Extraction Facility (TEF) at Savannah River Site • Processing the tritium at the Savannah River Site, which includes removal of nonhydrogen species and separation of the hydrogen isotopes of protium, deuterium and tritium.

  7. The glassy wormlike chain

    NASA Astrophysics Data System (ADS)

    Kroy, Klaus; Glaser, Jens

    2007-11-01

    We introduce a new model for the dynamics of a wormlike chain (WLC) in an environment that gives rise to a rough free energy landscape, which we name the glassy WLC. It is obtained from the common WLC by an exponential stretching of the relaxation spectrum of its long-wavelength eigenmodes, controlled by a single parameter \\boldsymbol{\\cal E} . Predictions for pertinent observables such as the dynamic structure factor and the microrheological susceptibility exhibit the characteristics of soft glassy rheology and compare favourably with experimental data for reconstituted cytoskeletal networks and live cells. We speculate about the possible microscopic origin of the stretching, implications for the nonlinear rheology, and the potential physiological significance of our results.

  8. Polymerase chain displacement reaction.

    PubMed

    Harris, Claire L; Sanchez-Vargas, Irma J; Olson, Ken E; Alphey, Luke; Fu, Guoliang

    2013-02-01

    Quantitative PCR assays are now the standard method for viral diagnostics. These assays must be specific, as well as sensitive, to detect the potentially low starting copy number of viral genomic material. We describe a new technique, polymerase chain displacement reaction (PCDR), which uses multiple nested primers in a rapid, capped, one-tube reaction that increases the sensitivity of normal quantitative PCR (qPCR) assays. Sensitivity was increased by approximately 10-fold in a proof-of-principle test on dengue virus sequence. In PCDR, when extension occurs from the outer primer, it displaces the extension strand produced from the inner primer by utilizing a polymerase that has strand displacement activity. This allows a greater than 2-fold increase of amplification product for each amplification cycle and therefore increased sensitivity and speed over conventional PCR. Increased sensitivity in PCDR would be useful in nucleic acid detection for viral diagnostics. PMID:23384180

  9. Energy transfer of nucleic acid products

    NASA Astrophysics Data System (ADS)

    Jung, Paul M.; Hu, Hsiang-Yun; Khalil, Omar S.

    1995-04-01

    Fluorescence energy transfer was investigated as a homogeneous detection method for the gapped ligase chain reaction (G-LCR). Oligonucleotides of a Chlamydia trachomatic G-LCR probe set were labeled with fluorescein as the donor and Texas Red as the acceptor fluorophore. Amplification and detection of 10 molecules of synthetic target was demonstrated in spiked urine samples.

  10. Chains, bombs, potrzebies and slugs

    NASA Astrophysics Data System (ADS)

    Jewess, Mike; McDowell, Alex; Maxfield, Stephen; Hunt, A. G.; Hicks, Bruce

    2010-03-01

    I read with pleasure Robert Crease's article on unusual units (February pp17-19). However, the article stated that an acre is 10×10 chains, when it is in fact 10×1 chains. Incidentally, a distance of 10 chains (220 yards) is known as a furlong, a word that suggests the length of a ploughed furrow and that is still used in horse-racing.

  11. Supply Chain Coordination in Hospitals

    NASA Astrophysics Data System (ADS)

    Rego, Nazaré; de Sousa, Jorge Pinho

    This paper presents an innovative approach to support the definition of strategies for the design of alternative configurations of hospital supply chains. This approach was developed around a hybrid Tabu Search / Variable Neighbourhood Search metaheuristic, that uses several neighbourhood structures. The flexibility of the procedure allows its application to supply chains with different topologies and atypical cost characteristics. A preliminary computational experience shows the approach potential in solving large scale supply chain configuration problems. The future incorporation of this approach in a broader Decision Support System (DSS) will provide a tool that can significantly contribute to an increase of healthcare supply chains efficiency and encourage the establishment of collaborative partnerships between their members.

  12. Dynamical Aspects of Inextensible Chains

    NASA Astrophysics Data System (ADS)

    Ferrari, Franco; Pyrka, Maciej

    In the present work, a method to impose the inextensibility constraints on the dynamics of a chain fluctuating in a thermal bath at fixed temperature is investigated. The final goal is to construct the probability function of the chain and the generating functional of the correlation functions of the relevant degrees of freedom of the system. First, we study the dynamics of a freely hinged chain composed by massive beads connected together by massless segments of fixed length. It is shown that a system of this kind may be described by a set of Langevin equations in which the noise is characterized by a non-gaussian probability distribution. Starting from these Langevin equations, the generating functional of the freely hinged chain is derived in path integral form. A connection with a stochastic process governed by a Fokker-Planck equation is established. Next, a chain composed by one-dimensional bars with constant mass distribution is considered. A path integral expression of the generating functional for a chain of this type is derived. Finally, it is verified that in the limit in which the chain becomes continuous, both generating functionals of the freely hinged chain and of the freely jointed bar chain converge to the same result as expected.

  13. Human laminin B2 chain

    SciTech Connect

    Pikkarainen, T.; Kallunki, T.; Tryggvason, K.

    1988-05-15

    The complete amino acid sequence of the human laminin B2 chains has been determined by sequencing of cDNA clones. The six overlapping clones studied cover approximately 7.5 kilobases of which 5312 nucleotides were sequenced from the 5' end. The open reading frame codes for a 33-residue signal peptide and a 1576-residue B2 chain proper, which is 189 residues less than in the highly homologous B1 chain. Computer analysis revealed that the B2 chain consists of distinct domains that contain helical structures, cysteine-rich repeats, and globular regions, as does the B1 chain. However, domain ..cap alpha.. and domain ..beta.. of the B1 chain have no counterpart in B2, and the number of cysteine-rich repeats is 12, or 1 less than in the B1 chain. The degree of homology between the two chains is highest in the cysteine repeat-containing domains III and V where 40% of the residues match. However, in helical domains I/II only 16% of residues match. The results demonstrate that the B1 and B2 chains of laminin are highly homologous proteins that are probably the products of related genes.

  14. Matrix product solutions of boundary driven quantum chains

    NASA Astrophysics Data System (ADS)

    Prosen, Tomaž

    2015-09-01

    We review recent progress on constructing non-equilibrium steady state density operators of boundary driven locally interacting quantum chains, where driving is implemented via Markovian dissipation channels attached to the chain’s ends. We discuss explicit solutions in three different classes of quantum chains, specifically, the paradigmatic (anisotropic) Heisenberg spin-1/2 chain, the Fermi-Hubbard chain, and the Lai-Sutherland spin-1 chain, and discuss universal concepts which characterize these solutions, such as matrix product ansatz and a more structured walking graph state ansatz. The central theme is the connection between the matrix product form of nonequilibrium states and the integrability structures of the bulk Hamiltonian, such as the Lax operators and the Yang-Baxter equation. However, there is a remarkable distinction with respect to the conventional quantum inverse scattering method, namely addressing nonequilibrium steady state density operators requires non-unitary irreducible representations of Yang-Baxter algebra which are typically of infinite dimensionality. Such constructions result in non-Hermitian, and often also non-diagonalisable families of commuting transfer operators which in turn result in novel conservation laws of the integrable bulk Hamiltonians. For example, in the case of the anisotropic Heisenberg model, quasi-local conserved operators which are odd under spin reversal (or spin flip) can be constructed, whereas the conserved operators stemming from orthodox Hermitian transfer operators (via logarithmic differentiation) are all even under spin reversal.

  15. Agent independent task planning

    NASA Technical Reports Server (NTRS)

    Davis, William S.

    1990-01-01

    Agent-Independent Planning is a technique that allows the construction of activity plans without regard to the agent that will perform them. Once generated, a plan is then validated and translated into instructions for a particular agent, whether a robot, crewmember, or software-based control system. Because Space Station Freedom (SSF) is planned for orbital operations for approximately thirty years, it will almost certainly experience numerous enhancements and upgrades, including upgrades in robotic manipulators. Agent-Independent Planning provides the capability to construct plans for SSF operations, independent of specific robotic systems, by combining techniques of object oriented modeling, nonlinear planning and temporal logic. Since a plan is validated using the physical and functional models of a particular agent, new robotic systems can be developed and integrated with existing operations in a robust manner. This technique also provides the capability to generate plans for crewmembers with varying skill levels, and later apply these same plans to more sophisticated robotic manipulators made available by evolutions in technology.

  16. An Abstract Argumentation Framework for Supporting Agreements in Agent Societies

    NASA Astrophysics Data System (ADS)

    Heras, Stella; Botti, Vicente; Julián, Vicente

    In this paper we present an abstract argumentation framework for the support of agreement processes in agent societies. This framework takes into account arguments, attacks between them and the social contex of the agents that put forward arguments. Then, we define the semantics of the framework, providing a mechanism to evaluate arguments in view of other arguments posed in the argumentation process. Finally, the framework is illustrated with an example in a real domain of a water-rights transfer market.

  17. Excitation energy transfer in the photosystem I

    SciTech Connect

    Webber, Andrew N

    2012-09-25

    Photosystem I is a multimeric pigment protein complex in plants, green alage and cyanobacteria that functions in series with Photosystem II to use light energy to oxidize water and reduce carbon dioxide. The Photosystem I core complex contains 96 chlorophyll a molecules and 22 carotenoids that are involved in light harvesting and electron transfer. In eucaryotes, PSI also has a peripheral light harvesting complex I (LHCI). The role of specific chlorophylls in excitation and electron transfer are still unresolved. In particular, the role of so-called bridging chlorophylls, located between the bulk antenna and the core electron transfer chain, in the transfer of excitation energy to the reaction center are unknown. During the past funding period, site directed mutagenesis has been used to create mutants that effect the physical properties of these key chlorophylls, and to explore how this alters the function of the photosystem. Studying these mutants using ultrafast absorption spectroscopy has led to a better understanding of the process by which excitation energy is transferred from the antenna chlorophylls to the electron transfer chain chlorophylls, and what the role of connecting chlorophylls and A_0 chlorophylls is in this process. We have also used these mutants to investigate whch of the central group of six chlorophylls are involved in the primary steps of charge separation and electron transfer.

  18. Chain Dynamics in Magnetorheological Suspensions

    NASA Technical Reports Server (NTRS)

    Gast, A. P.; Furst, E. M.

    1999-01-01

    Magnetorheological (MR) suspensions are composed of colloidal particles which acquire dipole moments when subjected to an external magnetic field. At sufficient field strengths and concentrations, the dipolar particles rapidly aggregate to form long chains. Subsequent lateral cross-linking of the dipolar chains is responsible for a rapid liquid-to-solid-like rheological transition. The unique, magnetically-activated rheological properties of MR suspensions make them ideal for interfacing mechanical systems to electronic controls. Additionally, the ability to experimentally probe colloidal suspensions interacting through tunable anisotropic potentials is of fundamental interest. Our current experimental work has focused on understanding the fluctuations of dipolar chains. It has been proposed by Halsey and Toor (HT) that the strong Landau-Peierls thermal fluctuations of dipolar chains could be responsible for long-range attractions between chains. Such interactions will govern the long-time relaxation of MR suspensions. We have synthesized monodisperse neutrally buoyant MR suspensions by density matching stabilized ferrofluid emulsion droplets with D2O. This allows us to probe the dynamics of the dipolar chains using light scattering without gravitational, interfacial, and polydispersity effects to resolve the short-wavelength dynamics of the dipolar chains. We used diffusing wave spectroscopy to measure these dynamics. The particle displacements at short times that show an independence to the field strength, but at long times exhibit a constrained, sub-diffusive motion that slows as the dipole strength is increased. The experiments are in good qualitative agreement with Brownian dynamics simulations of dipolar chains. Although there have been several important and detailed studies of the structure and interactions in MR suspensions, there has not been conclusive evidence that supports or contradicts the HT model prediction that long-range interactions exist between

  19. Modification of seizure disorders: the interruption of behavioral chains.

    PubMed Central

    Zlutnick, S; Mayville, W J; Moffat, S

    1975-01-01

    This study investigated the effects of interruption and differential reinforcement on seizures in children. Seizures were conceptualized as the terminal link in a behavioral chain, resulting in a strategy aimed at identifying and modifying behaviors that reliably preceded the seizure climax. Seizure frequency was reduced in four of five subjects, whereas the frequency of preseizure behavior was reduced in only three subjects. Parents and school personnel were successfully used as change agents. PMID:1141076

  20. MpcAgent

    SciTech Connect

    Nutaro, James

    2013-11-29

    MpcAgent software is a module for the VolltronLite platform from PNNL that regulates the operation of rooftop air conditioning units in small to medium commercial buildings for the purpose of reducing peak power consumption. The MpcAgent accomplishes this by restricting the number of units that may operate simultaneously and using a model predictive control strategy to select which units to operate in each control period. The outcome of this control is effective control of the building air temperature at the user specified set point while avoiding expensive peak demand charges that result from running all HVAC units simultaneously.

  1. MpcAgent

    Energy Science and Technology Software Center (ESTSC)

    2013-11-29

    MpcAgent software is a module for the VolltronLite platform from PNNL that regulates the operation of rooftop air conditioning units in small to medium commercial buildings for the purpose of reducing peak power consumption. The MpcAgent accomplishes this by restricting the number of units that may operate simultaneously and using a model predictive control strategy to select which units to operate in each control period. The outcome of this control is effective control of themore » building air temperature at the user specified set point while avoiding expensive peak demand charges that result from running all HVAC units simultaneously.« less

  2. Gadofullerene MRI contrast agents.

    PubMed

    Bolskar, Robert D

    2008-04-01

    A promising new class of MRI contrast-enhancing agents with high relaxivities is based on gadolinium-containing metallofullerenes, which are also termed gadofullerenes. Detailed study of the water-proton relaxivity properties and intermolecular nanoclustering behavior of gadofullerene derivatives has revealed valuable information about their relaxivity mechanisms and given a deeper understanding of this new class of paramagnetic contrast agent. Here, the latest findings on water-solubilized gadofullerene materials and how these findings relate to their future applications in MRI are reviewed and discussed. PMID:18373426

  3. Exploring membrane respiratory chains.

    PubMed

    Marreiros, Bruno C; Calisto, Filipa; Castro, Paulo J; Duarte, Afonso M; Sena, Filipa V; Silva, Andreia F; Sousa, Filipe M; Teixeira, Miguel; Refojo, Patrícia N; Pereira, Manuela M

    2016-08-01

    Acquisition of energy is central to life. In addition to the synthesis of ATP, organisms need energy for the establishment and maintenance of a transmembrane difference in electrochemical potential, in order to import and export metabolites or to their motility. The membrane potential is established by a variety of membrane bound respiratory complexes. In this work we explored the diversity of membrane respiratory chains and the presence of the different enzyme complexes in the several phyla of life. We performed taxonomic profiles of the several membrane bound respiratory proteins and complexes evaluating the presence of their respective coding genes in all species deposited in KEGG database. We evaluated 26 quinone reductases, 5 quinol:electron carriers oxidoreductases and 18 terminal electron acceptor reductases. We further included in the analyses enzymes performing redox or decarboxylation driven ion translocation, ATP synthase and transhydrogenase and we also investigated the electron carriers that perform functional connection between the membrane complexes, quinones or soluble proteins. Our results bring a novel, broad and integrated perspective of membrane bound respiratory complexes and thus of the several energetic metabolisms of living systems. This article is part of a Special Issue entitled 'EBEC 2016: 19th European Bioenergetics Conference, Riva del Garda, Italy, July 2-6, 2016', edited by Prof. Paolo Bernardi. PMID:27044012

  4. Agent Persuasion Mechanism of Acquaintance

    NASA Astrophysics Data System (ADS)

    Jinghua, Wu; Wenguang, Lu; Hailiang, Meng

    Agent persuasion can improve negotiation efficiency in dynamic environment based on its initiative and autonomy, and etc., which is being affected much more by acquaintance. Classification of acquaintance on agent persuasion is illustrated, and the agent persuasion model of acquaintance is also illustrated. Then the concept of agent persuasion degree of acquaintance is given. Finally, relative interactive mechanism is elaborated.

  5. 13 CFR 107.1620 - Functions of agents, including Central Registration Agent, Selling Agent and Fiscal Agent.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 13 Business Credit and Assistance 1 2010-01-01 2010-01-01 false Functions of agents, including Central Registration Agent, Selling Agent and Fiscal Agent. 107.1620 Section 107.1620 Business Credit and Assistance SMALL BUSINESS ADMINISTRATION SMALL BUSINESS INVESTMENT COMPANIES SBA Financial Assistance...

  6. 13 CFR 108.1620 - Functions of agents, including Central Registration Agent, Selling Agent and Fiscal Agent.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 13 Business Credit and Assistance 1 2010-01-01 2010-01-01 false Functions of agents, including Central Registration Agent, Selling Agent and Fiscal Agent. 108.1620 Section 108.1620 Business Credit and Assistance SMALL BUSINESS ADMINISTRATION NEW MARKETS VENTURE CAPITAL (âNMVCâ) PROGRAM SBA...

  7. Verifying the Hanging Chain Model

    ERIC Educational Resources Information Center

    Karls, Michael A.

    2013-01-01

    The wave equation with variable tension is a classic partial differential equation that can be used to describe the horizontal displacements of a vertical hanging chain with one end fixed and the other end free to move. Using a web camera and TRACKER software to record displacement data from a vibrating hanging chain, we verify a modified version…

  8. Developing sustainable food supply chains.

    PubMed

    Smith, B Gail

    2008-02-27

    This paper reviews the opportunities available for food businesses to encourage consumers to eat healthier and more nutritious diets, to invest in more sustainable manufacturing and distribution systems and to develop procurement systems based on more sustainable forms of agriculture. The important factors in developing more sustainable supply chains are identified as the type of supply chain involved and the individual business attitude to extending responsibility for product quality into social and environmental performance within their own supply chains. Interpersonal trust and working to standards are both important to build more sustainable local and many conserved food supply chains, but inadequate to transform mainstream agriculture and raw material supplies to the manufactured and commodity food markets. Cooperation among food manufacturers, retailers, NGOs, governmental and farmers' organizations is vital in order to raise standards for some supply chains and to enable farmers to adopt more sustainable agricultural practices. PMID:17766237

  9. Delocalization of mechanical waves in the ladder chain of DNA with correlated disorder

    NASA Astrophysics Data System (ADS)

    Farzadian, O.; Niry, M. D.

    2016-05-01

    Localization-delocalization transition of mechanical vibrations in a ladder chain with correlated disorder is studied analytically and numerically. An exact analytical analysis is carried out for the delocalization properties of the waves in the ladder chain. This analysis predicts resonance frequencies at which the waves can propagate in the entire chain like DNA. Our analytical results in prediction of extended modes are confirmed by numerical simulations using the transfer matrix method. Finally we consider the entropy of disorder as a control parameter for localization-delocalization transition in chain with correlated disorder.

  10. Can Subscription Agents Survive?

    ERIC Educational Resources Information Center

    Tuttle, Marcia

    1985-01-01

    With the saturation of traditional markets for their services, subscription agents have evolved from orders and invoices to serving customers by communicating with librarians and publishers and making automated and paper products available. Magazine fulfillment centers, publisher discounts, and electronic publishing will influence the subscription…

  11. Remote Agent Experiment

    NASA Technical Reports Server (NTRS)

    Benard, Doug; Dorais, Gregory A.; Gamble, Ed; Kanefsky, Bob; Kurien, James; Millar, William; Muscettola, Nicola; Nayak, Pandu; Rouquette, Nicolas; Rajan, Kanna; Norvig, Peter (Technical Monitor)

    2000-01-01

    Remote Agent (RA) is a model-based, reusable artificial intelligence (At) software system that enables goal-based spacecraft commanding and robust fault recovery. RA was flight validated during an experiment on board of DS1 between May 17th and May 21th, 1999.

  12. E-Learning Agents

    ERIC Educational Resources Information Center

    Gregg, Dawn G.

    2007-01-01

    Purpose: The purpose of this paper is to illustrate the advantages of using intelligent agents to facilitate the location and customization of appropriate e-learning resources and to foster collaboration in e-learning environments. Design/methodology/approach: This paper proposes an e-learning environment that can be used to provide customized…

  13. Battlefield agent collaboration

    NASA Astrophysics Data System (ADS)

    Budulas, Peter P.; Young, Stuart H.; Emmerman, Philip J.

    2001-09-01

    Small air and ground physical agents (robots) will be ubiquitous on the battlefield of the 21st century, principally to lower the exposure to harm of our ground forces in urban and open terrain scenarios. Teams of small collaborating physical agents conducting tasks such as Reconnaissance, Surveillance, and Target Acquisition (RSTA), intelligence, chemical and biological agent detection, logistics, decoy, sentry; and communications relay will have advanced sensors, communications, and mobility characteristics. It is anticipated that there will be many levels of individual and team collaboration between the soldier and robot, robot to robot, and robot to mother ship. This paper presents applications and infrastructure components that illustrate each of these levels. As an example, consider the application where a team of twenty small robots must rapidly explore and define a building complex. Local interactions and decisions require peer to peer collaboration. Global direction and information fusion warrant a central team control provided by a mother ship. The mother ship must effectively deliver/retrieve, service, and control these robots as well as fuse the information gathered by these highly mobile robot teams. Any level of collaboration requires robust communications, specifically a mobile ad hoc network. The application of fixed ground sensors and mobile robots is also included in this paper. This paper discusses on going research at the U.S. Army Research Laboratory that supports the development of multi-robot collaboration. This research includes battlefield visualization, intelligent software agents, adaptive communications, sensor and information fusion, and multi-modal human computer interaction.

  14. Mobility control agent

    SciTech Connect

    Argabright, P.A.; Phillips, B.L.; Rhudy, J.S.

    1983-05-17

    Polymer mobility control agents useful in supplemental oil recovery processes, which give improved reciprocal relative mobilities, are prepared by initiating the polymerization of a monomer containing a vinyl group with a catalyst comprising a persulfate and ferrous ammonium sulfate. The vinyl monomer is an acrylyl, a vinyl cyanide, a styryl and water soluble salts thereof.

  15. Mixed Species Ion Chains for Scalable Quantum Computation

    NASA Astrophysics Data System (ADS)

    Wright, John Albert

    Mixed species chains of barium and ytterbium ions are investigated as a tool for building scalable quantum computation devices. Ytterbium ions provide a stable, environmentally-insensitive qubit that is easily initialized and manipulated, while barium ions are easily entangled with photons that can allow quantum information to be transmitted between systems in modular quantum computation units. Barium and ytterbium are trapped together in a linear chain in a linear rf trap and their normal mode structure and the thermal occupation numbers of these modes are measured with a narrow band laser addressing an electric quadrupole transition in barium ions. Before these measurements, barium ions are directly cooled using Doppler cooling, while the ytterbium ions are sympathetically cooled by the barium. For radial modes strongly coupled to ytterbium ions the average thermal occupation numbers vary between 400 and 12,000 depending on ion species configuration and trap parameters. Ion chain temperatures are also measured using a technique based on ion species reordering. Surface traps with many dc electrodes provide the ability to controllably reorder the chain to optimize normal mode cooling, and initial work towards realizing this capability are discussed. Quantum information can be transferred between ions in a linear chain using an optical system that is well coupled to the motional degrees of freedom of the chain. For this reason, a 532 nm Raman system is developed and its expected performance is evaluated.

  16. [Quality of transfer. Biologist and clinician's point of view].

    PubMed

    Nogueira, D; Isnard, V; Fallet, C

    2010-04-01

    Embryonic transfer is one of the briefest procedures in the long-lasting chain of events occurring during an infertility treatment. Embryo transfer is, however, one of the most crucial steps in assisted reproductive technologies. The realization of this ultimate gesture involves the control of numerous parameters that exert an impact on its success. These various influential factors engage the multidisciplinary team: biologist, clinician... to permanently search for ways to optimize embryo transfer outcome. PMID:20728805

  17. Tutorial on agent-based modeling and simulation.

    SciTech Connect

    Macal, C. M.; North, M. J.; Decision and Information Sciences

    2005-01-01

    Agent-based modeling and simulation (ABMS) is a new approach to modeling systems comprised of autonomous, interacting agents. ABMS promises to have far-reaching effects on the way that businesses use computers to support decision-making and researchers use electronic laboratories to support their research. Some have gone so far as to contend that ABMS is a third way of doing science besides deductive and inductive reasoning. Computational advances have made possible a growing number of agent-based applications in a variety of fields. Applications range from modeling agent behavior in the stock market and supply chains, to predicting the spread of epidemics and the threat of bio-warfare, from modeling consumer behavior to understanding the fall of ancient civilizations, to name a few. This tutorial describes the theoretical and practical foundations of ABMS, identifies toolkits and methods for developing ABMS models, and provides some thoughts on the relationship between ABMS and traditional modeling techniques.

  18. Fluorescent sensors for organophosphorus nerve agent mimics.

    PubMed

    Dale, Trevor J; Rebek, Julius

    2006-04-12

    We present a small molecule sensor that provides an optical response to the presence of an organophosphorus (OP)-containing nerve agent mimic. The design contains three key features: a primary alcohol, a tertiary amine in close proximity to the alcohol, and a fluorescent group used as the optical readout. In the sensor's rest state, the lone pair of electrons of the basic amine quenches the fluorescence of the nearby fluorophore through photoinduced electron transfer (PET). Exposure to an OP nerve agent mimic triggers phosphorylation of the primary alcohol followed rapidly by an intramolecular substitution reaction as the amine displaces the created phosphate. The quaternized ammonium salt produced by this cyclization reaction no longer possesses a lone pair of electrons, and a fluorescence readout is observed as the nonradiative PET quenching pathway of the fluorophore is shut down. PMID:16594648

  19. Technology Transfer

    NASA Technical Reports Server (NTRS)

    Bullock, Kimberly R.

    1995-01-01

    The development and application of new technologies in the United States has always been important to the economic well being of the country. The National Aeronautics and Space Administration (NASA) has been an important source of these new technologies for almost four decades. Recently, increasing global competition has emphasized the importance of fully utilizing federally funded technologies. Today NASA must meet its mission goals while at the same time, conduct research and development that contributes to securing US economic growth. NASA technologies must be quickly and effectively transferred into commercial products. In order to accomplish this task, NASA has formulated a new way of doing business with the private sector. Emphasis is placed on forming mutually beneficial partnerships between NASA and US industry. New standards have been set in response to the process that increase effectiveness, efficiency, and timely customer response. This summer I have identified potential markets for two NASA inventions: including the Radially Focused Eddy Current Sensor for Characterization of Flaws in Metallic Tubing and the Radiographic Moire. I have also worked to establish a cooperative program with TAG, private industry, and a university known as the TAG/Industry/Academia Program.

  20. Entanglement Entropy in 1-D integrable chains

    NASA Astrophysics Data System (ADS)

    Franchini, Fabio; Evangelisti, Stefano; Ercolessi, Elisa; Ravanini, Francesco; de Luca, Andrea

    2012-02-01

    We study analytically the Renyi entropy of a bipartite lattice in the limit of two semi-infinite chains joined at the origin, for a few integrable 1-dimensional models, by using the techniques of Corner Transfer Matrices of the corresponding 2-D classical systems, namely the 8-vertex model and the RSOS. In the scaling limit, close to a conformal point, we reproduce the leading behavior expected from CFT prediction. The sub-leading corrections, however, differ from na"ive expectations and we show that lattice effect can give rise to additional relevant terms in any numerical approach. Moreover, in the vicinity of a non-conformal (ferromagnetic) point, we observe a violation of universality and a behavior of the entropy characteristic of an essential singularity.

  1. Asymptotic behavior of the entropy of chains placed on cylinders

    NASA Astrophysics Data System (ADS)

    Dantas, W. G.; de Oliveira, M. J.; Stilck, J. F.

    2007-09-01

    By using the transfer matrix approach, we investigate the asymptotic behavior of the entropy of flexible chains with M monomers each placed on strips with periodic boundary conditions (cylinders). In the limit of high density of monomers, we study the behavior of the entropy as a function of the density of monomers and the width of the strip, inspired by recent analytical studies of this problem for the particular case of dimers (M=2) . We obtain the entropy in the asymptotic regime of high densities for chains with M=2,…,9 monomers, as well as for the special case of polymers, where M→∞ , and find that the results show a regular behavior similar to the one found analytically for dimers. We also verify that in the low-density limit the mean-field expression for the entropy is followed by the results from our transfer matrix calculations.

  2. Food Chain Security and Vulnerability

    NASA Astrophysics Data System (ADS)

    Brunet, Sébastien; Delvenne, Pierre; Claisse, Frédéric

    In our contemporary societies, the food chain could be defined as a macro-technical system, which depends on a wide variety of actors and risks analysis methods. In this contribution, risks related to the food chain are defined in terms of "modern risks" (Beck 1992). The whole national economic sector of food production/distribution is vulnerable to a local accident, which can affect the functioning of food chain, the export programs and even the political system. Such a complex socio-technical environment is undoubtedly vulnerable to intentional act such as terrorism.

  3. Supersymmetric quantum spin chains and classical integrable systems

    NASA Astrophysics Data System (ADS)

    Tsuboi, Zengo; Zabrodin, Anton; Zotov, Andrei

    2015-05-01

    For integrable inhomogeneous supersymmetric spin chains (generalized graded magnets) constructed employing Y( gl( N| M))-invariant R-matrices in finite-dimensional representations we introduce the master T-operator which is a sort of generating function for the family of commuting quantum transfer matrices. Any eigenvalue of the master T-operator is the tau-function of the classical mKP hierarchy. It is a polynomial in the spectral parameter which is identified with the 0-th time of the hierarchy. This implies a remarkable relation between the quantum supersymmetric spin chains and classical many-body integrable systems of particles of the Ruijsenaars-Schneider type. As an outcome, we obtain a system of algebraic equations for the spectrum of the spin chain Hamiltonians.

  4. Distributed Agents for Autonomy

    NASA Astrophysics Data System (ADS)

    Blake, Rick; Amigoni, Francesco; Brambilla, Andrea; de la Rosa Steinz, Sonia; Lavagna, Michele; le Duc, Ian; Page, Jonathan; Page, Oliver; Steel, Robin; Wijnands, Quirien

    2010-08-01

    The Distributed Agents for Autonomy (DAFA) Study has been performed for ESA by SciSys UK Ltd, Vega GmbH and Politecnico di Milano. An analysis of past, present and future space missions has been conducted, structured around a set of three pre-defined mission scenarios: Formation Flying, Earth Observation and Planetary Exploration. This analysis led to the definition of a framework of use cases where the application of distributed autonomy seems necessary or appropriate, and a set of metrics that may be used to assess such deployments. Agent technology and architectures were extensively surveyed and the results used to elaborate each of the mission scenarios to the point where a software prototype could be constructed. Such a prototype was developed for a scenario based on the ExoMars mission and this has been used to highlight the advantages of a DAFA approach to the mission architecture.

  5. All chain Loran-C time synchronization

    NASA Technical Reports Server (NTRS)

    Sherman, H. T.

    1973-01-01

    A program is in progress to implement coordinated universal time (UTC) synchronization on all Loran-C transmissions. The present capability is limited to five Loran-C chains in which the tolerance is twenty-five microseconds with respect to UTC. Upon completion of the program, the transmissions of all Loran-C chains will be maintained within five microseconds of UTC. The improvement plan consists of equipping selected Loran-C transmitting stations for greater precision of frequency standard adjustment and improved monitoring capability. External time monitor stations will utilize television time transfer techniques with nearby SATCOM terminals where practicable, thus providing the requisite traceability to the Naval Observatory. The monitor equipment groups and the interrelationships with the ground station equipment are discussed. After a brief review of control doctrine, forth-coming improvements to transmitting stations and how the time monitor and navigation equipments will complement each other resulting in improved service to all users of the Loran-C system are described.

  6. Rigid bifunctional chelating agents

    DOEpatents

    Sweet, Mark P.; Mease, Ronnie C.; Srivastava, Suresh C.

    1998-07-21

    Bicyclo›2.2.2! octane-2,3 diamine-N,N,N',N'-tetraacetic acids (BODTA) and bicyclo›2.2.1! heptane-2,3 diamine-N,N,N',N'-tetraacetic acid (BHDTA) are chelating agents useful in forming detectably labeled bioconjugate compounds for diagnostic and therapeutic purposes. New compounds and processes of forming BODTA and BHDTA are disclosed. Radioimmunoconjugates of the present invention show high and prolonged tumor uptake with low normal tissue uptakes.

  7. Rigid bifunctional chelating agents

    DOEpatents

    Sweet, Mark P.; Mease, Ronnie C.; Srivastava, Suresh C.

    2000-02-08

    Bicyclo[2.2.2]octane-2,3 diamine-N,N,N',N'-tetraacetic acids (BODTA) and bicyclo[2.2.1]heptane-2,3 diamine-N,N,N',N'-tetraacetic acid (BHDTA) are chelating agents useful in forming detectably labeled bioconjugate compounds for diagnostic and therapeutic purposes. New compounds and processes of forming BODTA and BHDTA are disclosed. Radioimmunoconjugates of the present invention show high and prolonged tumor uptake with low normal tissue uptakes.

  8. Surface polymerization agents

    SciTech Connect

    Taylor, C.; Wilkerson, C.

    1996-12-01

    This is the final report of a 1-year, Laboratory-Directed R&D project at LANL. A joint technical demonstration was proposed between US Army Missile Command (Redstone Arsenal) and LANL. Objective was to demonstrate that an unmanned vehicle or missile could be used as a platform to deliver a surface polymerization agent in such a manner as to obstruct the filters of an air-breathing mechanism, resulting in operational failure.

  9. Rigid bifunctional chelating agents

    DOEpatents

    Sweet, M.P.; Mease, R.C.; Srivastava, S.C.

    1998-07-21

    Bicyclo[2.2.2] octane-2,3 diamine-N,N,N`,N`-tetraacetic acids (BODTA) and bicyclo[2.2.1] heptane-2,3 diamine-N,N,N`,N`-tetraacetic acid (BHDTA) are chelating agents useful in forming detectably labeled bioconjugate compounds for diagnostic and therapeutic purposes. New compounds and processes of forming BODTA and BHDTA are disclosed. Radioimmunoconjugates of the present invention show high and prolonged tumor uptake with low normal tissue uptakes.

  10. 76 FR 30092 - Notice of Request for Extension of Approval of an Information Collection; Select Agent Registration

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-05-24

    ... Collection; Select Agent Registration AGENCY: Animal and Plant Health Inspection Service, USDA. ACTION... information regarding the select agent registration process associated with the possession, use, or transfer..., Agriculture Select Agent Program, RIPPS, PPQ, APHIS, 4700 River Road, Unit 2, Riverdale, MD 20737; (301)...

  11. 46 CFR 315.6 - Transferred vessels and contracts.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 8 2011-10-01 2011-10-01 false Transferred vessels and contracts. 315.6 Section 315.6... AGREEMENTS AND APPPOINTMENT OF AGENTS § 315.6 Transferred vessels and contracts. The requirements of § 315.5(a)(1) shall not apply to a contractor managing vessels owned by the United States under a...

  12. Perioperative allergy: uncommon agents.

    PubMed

    Caimmi, S; Caimmi, D; Cardinale, F; Indinnimeo, L; Crisafulli, G; Peroni, D G; Marseglia, G L

    2011-01-01

    Anesthesia may often be considered as a high-risk procedure and anaphylaxis remains a major cause of concern for anesthetists who routinely administer many potentially allergenic agents. Neuromuscular blocking agents, latex and antibiotics are the substances involved in most of the reported reactions. Besides these three agents, a wide variety of substances may cause an anaphylactic reaction during anesthesia. Basically all the administered drugs or substances may be potential causes of anaphylaxis. Among them, those reported the most in literature include hypnotics, opioids, local anesthetics, colloids, dye, Non-Steroidal Anti-Inflammatory Drugs (NSAIDs), Iodinated Contrast Media (ICM), antiseptics, aprotinin, ethylene oxyde and formaldehyde, and protamine and heparins. No premedication can effectively prevent an allergic reaction and a systematic preoperative screening is not justified for all patients; nevertheless, an allergy specialist should evaluate those patients with a history of anesthesia-related allergy. Patients must be fully informed of investigation results, and advised to provide a detailed report prior to future anesthesia. PMID:22014927

  13. Long chain fatty acids and dietary fats in fetal nutrition

    PubMed Central

    Cetin, Irene; Alvino, Gioia; Cardellicchio, Manuela

    2009-01-01

    Long chain polyunsaturated fatty acids are essential nutrients for a healthy diet. The different kinds consumed by the mother during gestation and lactation may influence pregnancy, fetal and also neonatal outcome. The amount of fatty acids transferred from mother to fetus depends not only on maternal metabolism but also on placental function, i.e. by the uptake, metabolism and then transfer of fatty acids to the fetus. The third trimester of gestation is characterized by an increase of long chain polyunsaturated fatty acids in the fetal circulation, in particular docosahexaenoic acid, especially to support brain growth and visual development. These mechanisms may be altered in pathological conditions, such as intrauterine growth restriction and diabetes, when maternal and fetal plasma levels of long chain polyunsaturated fatty acids undergo significant changes. The aim of this review is to describe the maternal and placental factors involved in determining fetal fatty acid availability and metabolism, focusing on the specific role of long chain polyunsaturated fatty acids in normal and pathological pregnancies. PMID:19528253

  14. A nano-sized PARACEST-fluorescence imaging contrast agent facilitates & validates in vivo CEST MRI detection of glioma

    PubMed Central

    Ali, Meser M; Bhuiyan, Mohammed PI; Janic, Branislava; Varma, Nadimpalli RS; Mikkelsen, Tom; Ewing, James R; Knight, Robert A; Pagel, Mark D; Arbab, Ali S

    2012-01-01

    Aim The authors have investigated the usefulness of in vivo chemical exchange saturation transfer MRI for detecting gliomas using a dual-modality imaging contrast agent. Materials & methods A paramagnetic chemical exchange saturation transfer MRI contrast agent, Eu-1,4,7,10-tetraazacclododecane-1,4,7,10-tetraacetic acid-Gly4 and a fluorescent agent, DyLight® 680, were conjugated to a generation 5 polyamidoamine dendrimer to create the dual-modality, nano-sized imaging contrast agent. Results The agent was detected with in vivo chemical exchange saturation transfer MRI in an U87 glioma model. These results were validated using in vivo and ex vivo fluorescence imaging. Conclusion This study demonstrated the merits of using a nano-sized imaging contrast agent for detecting gliomas and using a dual-modality agent for detecting gliomas at different spatial scales. PMID:22891866

  15. Mn2+ activates skinned smooth muscle cells in the absence of myosin light chain phosphorylation.

    PubMed

    Hoar, P E; Kerrick, W G

    1988-08-01

    Two effects of Mn2+ on skinned fibers from chicken gizzard smooth muscle were observed, dependent on the presence or absence of dithiothreitol (DTT) reducing agent. One involves protein oxidation (in the absence of DTT) with production of a "latch"-like state, and the other involves direct Mn2+ activation of contractile proteins. Cells activated by Mn2+ in the presence of ATP and the absence of Ca2+, Mg2+ and DTT did not relax when transferred to normal relaxing solutions. In contrast, when 5 mM DTT was included in the Mn2+ contracting solution to prevent protein oxidation by Mn2+, the cells still contracted when exposed to Mn2+, but relaxed rapidly when the Mn2+ was removed. In the presence of DTT both the Mn2+ activation and the relaxation following removal of Mn2+ were more rapid than normal Ca2+-activated contractions and relaxations. The skinned fibers activated by Mn2+ in the absence of DTT showed little active shortening unless DTT was added. This rigor-like state is probably due to oxidation of contractile proteins since the cells relaxed when exposed to a relaxing solution containing DTT (50 mM) and then contracted again in response to Ca2+ and relaxed normally. The Mn2+ activation was not associated with myosin light chain phosphorylation, in contrast to Ca2+-activated contractions. PMID:3186428

  16. Bibliometric Application of Markov Chains.

    ERIC Educational Resources Information Center

    Pao, Miranda Lee; McCreery, Laurie

    1986-01-01

    A rudimentary description of Markov Chains is presented in order to introduce its use to describe and to predict authors' movements among subareas of the discipline of ethnomusicology. Other possible applications are suggested. (Author)

  17. Effect of Molecular Interactions on Electron-Transfer and Antioxidant Activity of Bis(alkanol)selenides: A Radiation Chemical Study.

    PubMed

    Kumar, Pavitra V; Singh, Beena G; Phadnis, Prasad P; Jain, Vimal K; Priyadarsini, K Indira

    2016-08-16

    Understanding electron-transfer processes is crucial for developing organoselenium compounds as antioxidants and anti-inflammatory agents. To find new redox-active selenium antioxidants, we have investigated one-electron-transfer reactions between hydroxyl ((.) OH) radical and three bis(alkanol)selenides (SeROH) of varying alkyl chain length, using nanosecond pulse radiolysis. (.) OH radical reacts with SeROH to form radical adduct, which is converted primarily into a dimer radical cation (>Se∴Se<)(+) and α-{bis(hydroxyl alkyl)}-selenomethine radical along with a minor quantity of an intramolecularly stabilized radical cation. Some of these radicals have been subsequently converted to their corresponding selenoxide, and formaldehyde. Estimated yield of these products showed alkyl chain length dependency and correlated well with their antioxidant ability. Quantum chemical calculations suggested that compounds that formed more stable (>Se∴Se<)(+) , produced higher selenoxide and lower formaldehyde. Comparing these results with those for sulfur analogues confirmed for the first time the distinctive role of selenium in making such compounds better antioxidants. PMID:27405246

  18. Learning in engineered multi-agent systems

    NASA Astrophysics Data System (ADS)

    Menon, Anup

    graph (communication graph) and, under certain conditions, prove convergence of agent joint action (under eITEL) to the welfare optimizing set. The main condition requires that the union of interaction and communication graphs be strongly connected; thus the algorithm combines an implicit form of communication (via interactions through utility functions) with explicit inter-agent communications to achieve the given collaborative goal. This work has kinship with certain evolutionary computation techniques such as Simulated Annealing; the algorithm steps are carefully designed such that it describes an ergodic Markov chain with a stationary distribution that has support over states where agent joint actions optimize the welfare function. The main analysis tool is perturbed Markov chains and results of broader interest regarding these are derived as well. The other algorithm, Collaborative Extremum Seeking (CES), uses techniques from extremum seeking control to solve the problem when agent actions are drawn from the set of real numbers. In this case, under the assumption of existence of a local minimizer for the welfare function and a connected undirected communication graph between agents, a result regarding convergence of joint action to a small neighborhood of a local optimizer of the welfare function is proved. Since extremum seeking control uses a simultaneous gradient estimation-descent scheme, gradient information available in the continuous action space formulation is exploited by the CES algorithm to yield improved convergence speeds. The effectiveness of this algorithm for the wind farm power maximization problem is evaluated via simulations. Lastly, we turn to a different question regarding role of the information exchange pattern on performance of distributed control systems by means of a case study for the vehicle platooning problem. In the vehicle platoon control problem, the objective is to design distributed control laws for individual vehicles in a platoon

  19. 42 CFR 73.5 - Exemptions for HHS select agents and toxins.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... is transferred in accordance with § 73.16 or destroyed on-site by a recognized sterilization or... or destroyed on-site by a recognized sterilization or inactivation process, (2) The select agent...

  20. 42 CFR 73.5 - Exemptions for HHS select agents and toxins.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... is transferred in accordance with § 73.16 or destroyed on-site by a recognized sterilization or... or destroyed on-site by a recognized sterilization or inactivation process, (2) The select agent...