Sample records for bifunctional initiator bearing

  1. Concurrent initialization for Bearing-Only SLAM.

    PubMed

    Munguía, Rodrigo; Grau, Antoni

    2010-01-01

    Simultaneous Localization and Mapping (SLAM) is perhaps the most fundamental problem to solve in robotics in order to build truly autonomous mobile robots. The sensors have a large impact on the algorithm used for SLAM. Early SLAM approaches focused on the use of range sensors as sonar rings or lasers. However, cameras have become more and more used, because they yield a lot of information and are well adapted for embedded systems: they are light, cheap and power saving. Unlike range sensors which provide range and angular information, a camera is a projective sensor which measures the bearing of images features. Therefore depth information (range) cannot be obtained in a single step. This fact has propitiated the emergence of a new family of SLAM algorithms: the Bearing-Only SLAM methods, which mainly rely in especial techniques for features system-initialization in order to enable the use of bearing sensors (as cameras) in SLAM systems. In this work a novel and robust method, called Concurrent Initialization, is presented which is inspired by having the complementary advantages of the Undelayed and Delayed methods that represent the most common approaches for addressing the problem. The key is to use concurrently two kinds of feature representations for both undelayed and delayed stages of the estimation. The simulations results show that the proposed method surpasses the performance of previous schemes. PMID:22294884

  2. Kinetic modeling of free radical polymerization of styrene initiated by the bifunctional initiator 2,5-dimethyl-2,5-bis(2-ethyl hexanoyl peroxy)hexane

    Microsoft Academic Search

    L Cavin; A Rouge; Th Meyer; A Renken

    2000-01-01

    This paper deals with the kinetic study of bulk free radical polymerization of styrene initiated with the commercial bifunctional initiator 2,5-dimethyl-2,5-bis(2-ethyl hexanoyl peroxy)hexane (Lupersol 256). The polymerization kinetics is investigated by DSC measurement for temperatures between 80 and 110°C and for initiator initial concentration from 0.115 up to 0.46mol%. The experimental conversion and reaction rate are compared and discussed with

  3. INITIAL DEVELOPMENT OF A FORCE-SENSITIVE VIBRATION ISOLATION BEARING

    E-print Network

    Talbot, James P.

    172 Chapter 6 INITIAL DEVELOPMENT OF A FORCE-SENSITIVE VIBRATION ISOLATION BEARING The theoretical-sensitive vibration isolation bearing. The concept of such a device is described, together with the design and testing of a practical force-sensitive bearing for base-isolated buildings. 6.1. The Concept of a Force

  4. 75 FR 3444 - Ball Bearings and Parts Thereof From Germany: Initiation of Antidumping Duty Changed...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-01-21

    ...Administration [A-428-801] Ball Bearings and Parts Thereof From Germany: Initiation...of the antidumping duty order on ball bearings and parts thereof from Germany with respect...published antidumping duty orders on ball bearings, cylindrical roller bearings, and...

  5. 76 FR 10335 - Ball Bearings and Parts Thereof From Germany: Initiation of Antidumping Duty Changed...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-02-24

    ...Administration [A-428-801] Ball Bearings and Parts Thereof From Germany: Initiation...of the antidumping duty order on ball bearings and parts thereof from Germany with respect...published an antidumping duty order on ball bearings and parts thereof from Germany on...

  6. Sequential Bearings-Only-Tracking Initiation with Particle Filtering Method

    PubMed Central

    Hao, Chengpeng

    2013-01-01

    The tracking initiation problem is examined in the context of autonomous bearings-only-tracking (BOT) of a single appearing/disappearing target in the presence of clutter measurements. In general, this problem suffers from a combinatorial explosion in the number of potential tracks resulted from the uncertainty in the linkage between the target and the measurement (a.k.a the data association problem). In addition, the nonlinear measurements lead to a non-Gaussian posterior probability density function (pdf) in the optimal Bayesian sequential estimation framework. The consequence of this nonlinear/non-Gaussian context is the absence of a closed-form solution. This paper models the linkage uncertainty and the nonlinear/non-Gaussian estimation problem jointly with solid Bayesian formalism. A particle filtering (PF) algorithm is derived for estimating the model's parameters in a sequential manner. Numerical results show that the proposed solution provides a significant benefit over the most commonly used methods, IPDA and IMMPDA. The posterior Cramér-Rao bounds are also involved for performance evaluation. PMID:24453865

  7. 78 FR 2984 - Silver Bear Power, LLC; Supplemental Notice That Initial Market-Based Rate Filing Includes...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-01-15

    ...Regulatory Commission [Docket No. ER13-733-000] Silver Bear Power, LLC; Supplemental Notice That Initial Market- Based...supplemental notice in the above-referenced proceeding, of Silver Bear Power, LLC's application for market-based rate...

  8. 78 FR 50410 - Black Bear Development Holdings, LLC; Supplemental Notice that Initial Market-Based Rate Filing...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-08-19

    ...Regulatory Commission [Docket No. ER13-2143-000] Black Bear Development Holdings, LLC; Supplemental Notice that Initial...supplemental notice in the above-referenced proceeding of Black Bear Development Holdings, LLC's application for...

  9. 77 FR 47624 - Tall Bear Group, LLC; Supplemental Notice That Initial Market-Based Rate Filing Includes Request...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-08-09

    ...Regulatory Commission [Docket No. ER12-2374-000] Tall Bear Group, LLC; Supplemental Notice That Initial Market- Based...supplemental notice in the above-referenced proceeding, of Tall Bear Group, LLC's application for market-based rate...

  10. Mechanism of dent initiated flaking and bearing life enhancement technology under contaminated lubrication condition

    Microsoft Academic Search

    T. Ueda; N. Mitamura

    2008-01-01

    In this paper, we have clarified experimentally the mechanism of dent initiated flaking as observed in rolling element bearings operating under contaminated lubrication conditions. A characteristic of dent initiated flaking is the initiation of cracks on the trailing edge of dents relative to the rolling direction. Based on the results of twin-disk testing and ball-on-rod rolling contact fatigue (RCF) testing

  11. Bears, Bears, Bears!

    NSDL National Science Digital Library

    Ms.Beason

    2011-04-16

    What are some things you learned about bears? Use these websites to find out about bears: Parts of a Bear Polar Bears Real Story of the Three Bears The truth about bears Brown Bears Now fill in your chart! Bear Fact Sheet Listen to your teacher for further instruction on completing a book about bears! ...

  12. Undelayed Initialization in Bearing Only SLAM Joan Sol`a, Andre Monin, Michel Devy and Thomas Lemaire

    E-print Network

    Monin, André

    Undelayed Initialization in Bearing Only SLAM Joan Sol`a, Andr´e Monin, Michel Devy and Thomas to the SLAM problem in robotics have utilized Range and Bearing sensors as the provided perception data Bearing-Only information because the distance to the perceived landmarks is not directly provided. A whole

  13. MONTE CARLO INITIALIZATION FOR MULTI-SENSOR BEARING ONLY TRACKING Alon Shalev Housfater, Xiao-Ping Zhang Yifeng Zhou

    E-print Network

    Zhang, Xiao-Ping

    MONTE CARLO INITIALIZATION FOR MULTI-SENSOR BEARING ONLY TRACKING Alon Shalev Housfater, Xiao- distribution is assumed to be a uniform distribution between sensor bearing only tracking is developed. Multiple bearing observations are bution is sampled in a deterministic manner using a geometric used

  14. Novel ferrocene-based bifunctional amine-thioureas for asymmetric Michael addition of acetylacetone to nitroolefins.

    PubMed

    Ren, Xiaochen; He, Chunyan; Feng, Yingle; Chai, Yonghai; Yao, Wei; Chen, Weiping; Zhang, Shengyong

    2015-05-01

    An efficient method was developed to synthesize ferrocene-based bifunctional amine-thioureas bearing multiple hydrogen-bonding donors. Asymmetric Michael addition of acetylacetone to nitroolefins catalyzed by these novel bifunctional catalysts affords the Michael adducts in high yield and moderate to excellent enantioselectivities. Multiple hydrogen-bonds play an important role in accelerating the reaction. PMID:25832649

  15. Fatigue crack initiation and propagation in a quenched and tempered niobium bearing HSLA steel

    Microsoft Academic Search

    S. I. Kwun; R. A. Fournelle

    1982-01-01

    The fatigue crack initiation and propagation behavior of a niobium bearing HSLA steel heat treated to give two tempered martensitic\\u000a microstructures presumably with and without fine niobium carbides has been studied by light microscopy, electron microscopy,\\u000a and strain gage measurements of plastic zone deformation. The high cycle, stress controlled fatigue life of the steel in both\\u000a heat treated conditions was

  16. 77 FR 66975 - Black Bear SO, LLC; Supplemental Notice That Initial Market-Based Rate Filing Includes Request...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-11-08

    ...Regulatory Commission [Docket No. ER13-203-000] Black Bear SO, LLC; Supplemental Notice That Initial Market-Based Rate...supplemental notice in the above-referenced proceeding of Black Bear SO, LLC's application for market-based rate...

  17. Mechanism of dent initiated flaking and bearing life enhancement technology under contaminated lubrication condition. Part II: Effect of rolling element surface roughness on flaking resulting from dents, and life enhancement technology of rolling bearings under contaminated lubrication condition

    Microsoft Academic Search

    T. Ueda; N. Mitamura

    2009-01-01

    The dent initiated flaking life of a bearing is sometimes shorter than the calculated life. Therefore, it is important to develop an enhanced-life bearing for contaminated lubrication conditions. In this paper, the authors indicated that the dent initiated flaking life of a raceway is significantly reduced in bearings where the general surface roughness of the rolling elements is increased by

  18. Fatigue crack initiation and propagation in a quenched and tempered niobium bearing HSLA steel

    NASA Astrophysics Data System (ADS)

    Kwun, S. I.; Fournelle, R. A.

    1982-03-01

    The fatigue crack initiation and propagation behavior of a niobium bearing HSLA steel heat treated to give two tempered martensitic microstructures presumably with and without fine niobium carbides has been studied by light microscopy, electron microscopy, and strain gage measurements of plastic zone deformation. The high cycle, stress controlled fatigue life of the steel in both heat treated conditions was quite similar with the steel presumably containing the fine niobium carbides having slightly better resistance at low stress amplitudes. This slightly better high cycle resistance is associated with better resistance to fatigue crack initiation for this heat treatment. The fatigue crack propagation behavior of the steel was the opposite. The steel presumably containing the fine niobium carbides exhibited a much faster fatigue crack growth rate than that without them. The difference in growth rates is explained in terms of the plastic work expended during the propagation of the fatigue crack.

  19. Bifunctional oxygen electrodes

    Microsoft Academic Search

    D. Tryk; W. Aldred; Z. Chen; C. Fierro; J. Hashiguchi; M. Hossain; Z. Zhang; F. Zhao

    1985-01-01

    The objective of the research on bifunctional oxygen electrodes for alkaline electrolytes was to improve significantly both the cathodic and anodic polarization as well as the cycle life of such electrodes. The research has focused on finding high-efficiency, long-life electrocatalysts for O2 reduction and generation and achieving an understanding of the mechanisms of the catalysis. Catalyst systems which have been

  20. Bifunctional redox flow battery

    Microsoft Academic Search

    Y. H. Wen; J. Cheng; Y. Xun; P. H. Ma; Y. S. Yang

    2008-01-01

    A new bifunctional redox flow battery (BRFB) system, V(III)\\/V(II)—l-cystine(O2), was systematically investigated by using different separators. It is shown that during charge, water transfer is significantly restricted with increasing the concentration of HBr when the Nafion 115 cation exchange membrane is employed. The same result can be obtained when the gas diffusion layer (GDL) hot-pressed separator is used. The organic

  1. Bifunctional transition metal-based molecular catalysts for asymmetric syntheses.

    PubMed

    Ikariya, Takao; Murata, Kunihiko; Noyori, Ryoji

    2006-02-01

    The discovery and development of conceptually new chiral bifunctional transition metal-based catalysts for asymmetric reactions is described. The chiral bifunctional Ru catalyst was originally developed for asymmetric transfer hydrogenation of ketones and imines and is now successfully applicable to enantioselective C-C bond formation reaction with a wide scope and high practicability. The deprotonation of 1,3-dicarbonyl compounds with the chiral amido Ru complexes leading to the amine Ru complexes bearing C- or O-bonded enolates, followed by further reactions with electrophlies gives C-C bond formation products. The present bifunctional Ru catalyst offers a great opportunity to open up new fundamentals for stereoselective molecular transformation including enantioselective C-H and C-C as well as C-O, C-N bond formation. PMID:16446796

  2. Bifunctional Asymmetric Catalysis

    PubMed Central

    PAULL, DANIEL H.; ABRAHAM, CIBY J.; SCERBA, MICHAEL T.; ALDEN-DANFORTH, ETHAN; LECTKA, THOMAS

    2008-01-01

    CONSPECTUS In the field of catalytic, asymmetric synthesis, there is a growing emphasis on multifunctional systems, in which multiple parts of a catalyst or multiple catalysts work together to promote a specific reaction. These efforts, in part, are result-driven, and they are also part of a movement toward emulating the efficiency and selectivity of nature’s catalysts, enzymes. In this Account, we illustrate the importance of bifunctional catalytic methods, focusing on the cooperative action of Lewis acidic and Lewis basic catalysts by the simultaneous activation of both electrophilic and nucleophilic reaction partners. For our part, we have contributed three separate bifunctional methods that combine achiral Lewis acids with chiral cinchona alkaloid nucleophiles, for example, benzoylquinine (BQ), to catalyze highly enantioselective cycloaddition reactions between ketene enolates and various electrophiles. Each method requires a distinct Lewis acid to coordinate and activate the electrophile, which in turn increases the reaction rates and yields, without any detectable influence on the outstanding enantioselectivities inherent to these reactions. To place our results in perspective, many important contributions to this emerging field are highlighted and our own reports are chronicled. PMID:18402470

  3. The Sensitivity of Convective Initiation to the Lapse Rate of the Active Cloud-Bearing Layer

    E-print Network

    Niyogi, Dev

    (DCI) to the lapse rate of the active cloud-bearing layer [ACBL; the atmo- spheric layer above, only the three environments with the largest ACBL lapse rates support DCI. The simulated deep of parcel dilution. In one experiment without deep convection, DCI failure occurs even though thermal

  4. Fatigue crack initiation from small defects under low stress ratios in SAE52100 bearing steel

    Microsoft Academic Search

    Y. Hino; H. Matsunaga

    2009-01-01

    Axial-loading fatigue tests were carried out under low stress ratios, R = -? ~ -5.33, by use of a cylindrical specimen of SAE52100 bearing steel having drill holes of 50 ~ 200 mum in diameter. The maximum stresses, sigmamax = 0 ~ 300 MPa were combined with the minimum stresses, sigmamin of -1600 or -1800 MPa. Even at sigmamax =

  5. Leucine-rich diet alters the eukaryotic translation initiation factors expression in skeletal muscle of tumour-bearing rats

    PubMed Central

    Ventrucci, Gislaine; Mello, Maria Alice R; Gomes-Marcondes, Maria Cristina C

    2007-01-01

    Background Cancer-cachexia induces a variety of metabolic disorders on protein turnorver, decreasing protein synthesis and increasing protein degradation. Controversly, insulin, other hormones, and branched-chain amino acids, especially leucine, stimulate protein synthesis and modulate the activity of translation initiation factors involved in protein synthesis. Since the tumour effects are more pronounced when associated with pregnancy, ehancing muscle-wasting proteolysis, in this study, the influence of a leucine-rich diet on the protein synthesis caused by cancer were investigated. Methods Pregnant rats with or without Walker 256 tumour were distributed into six groups. During 20 days of experiment, three groups were fed with a control diet: C – pregnant control, W – tumour-bearing, and P – pair-fed, which received the same amount of food as ingested by the W group; three other groups of pregnant rats were fed a leucine-rich diet: L – pregnant leucine, WL – tumour-bearing, and PL – pair-fed, which received the same amount of food as ingested by the WL group. Results The gastrocnemius muscle of WL rats showed increased incorporation of leucine in protein compared to W rats; the leucine-rich diet also prevented the decrease in plasma insulin normally seen in W. The expression of translation initiation factors increased when tumour-bearing rats fed leucine-rich diet, with increase of ~35% for eIF2? and eIF5, ~17% for eIF4E and 20% for eIF4G; the expression of protein kinase S6K1 and protein kinase C was also highly enhanced. Conclusion The results suggest that a leucine-rich diet increased the protein synthesis in skeletal muscle in tumour-bearing rats possibly through the activation of eIF factors and/or the S6kinase pathway. PMID:17341295

  6. Dissociation behavior of a bifunctional tempo-active ester reagent for peptide structure analysis by free radical initiated peptide sequencing (FRIPS) mass spectrometry.

    PubMed

    Ihling, Christian; Falvo, Francesco; Kratochvil, Isabel; Sinz, Andrea; Schäfer, Mathias

    2015-02-01

    We have synthesized a homobifunctional active ester cross-linking reagent containing a TEMPO (2,2,6,6-tetramethylpiperidine-1-oxy) moiety connected to a benzyl group (Bz), termed TEMPO-Bz-linker. The aim for designing this novel cross-linker was to facilitate MS analysis of cross-linked products by free radical initiated peptide sequencing (FRIPS). The TEMPO-Bz-linker was reacted with all 20 proteinogenic amino acids as well as with model peptides to gain detailed insights into its fragmentation mechanism upon collision activation. The final goal of this proof-of-principle study was to evaluate the potential of the TEMPO-Bz-linker for chemical cross-linking studies to derive 3D-structure information of proteins. Our studies were motivated by the well documented instability of the central NO-C bond of TEMPO-Bz reagents upon collision activation. The fragmentation of this specific bond was investigated in respect to charge states and amino acid composition of a large set of precursor ions resulting in the identification of two distinct fragmentation pathways. Molecular ions with highly basic residues are able to keep the charge carriers located, i.e. protons or sodium cations, and consequently decompose via a homolytic cleavage of the NO-C bond of the TEMPO-Bz-linker. This leads to the formation of complementary open-shell peptide radical cations, while precursor ions that are protonated at the TEMPO-Bz-linker itself exhibit a charge-driven formation of even-electron product ions upon collision activation. MS(3) product ion experiments provided amino acid sequence information and allowed determining the cross-linking site. Our study fully characterizes the CID behavior of the TEMPO-Bz-linker and demonstrates its potential, but also its limitations for chemical cross-linking applications utilizing the special features of open-shell peptide ions on the basis of selective tandem MS analysis. PMID:25800022

  7. Redirecting splicing with bifunctional oligonucleotides

    E-print Network

    Perreault, Jean-Pierre

    oligonucleotides made of an antisense portion that determines target specificity, and a non- hybridizing tailRedirecting splicing with bifunctional oligonucleotides Jean-Philippe Brosseau1,2 , Jean-Franc¸ ois, for targeted oligonucleotide silencer of splicing and targeted oligonucleotide enhancer of splicing). The use

  8. Bifunctional oxygen electrodes. Final report

    Microsoft Academic Search

    D. Tryk; W. Aldred; Z. Chen; C. Fierro; J. Hashiguchi; M. Hossain; Z. Zhang; F. Zhao

    1985-01-01

    Objective of the research on bifunctional oxygen electrodes for alkaline electrolytes has been to improve significantly both the cathodic and anodic polarization as well as the cycle life of such electrodes. The research has focused on finding high-efficiency, long-life electrocatalysts for Oâ reduction and generation and achieving an understanding of the mechanisms of the catalysis. Catalyst systems which have been

  9. Desiccation of phyllosilicate-bearing samples as analog for desiccation cracks on Mars: Experimental setup and initial results

    NASA Astrophysics Data System (ADS)

    El-Maarry, M. R.; Pommerol, A.; Thomas, N.

    2015-06-01

    The surface of Mars is host to many regions displaying polygonal crack patterns that have been identified as potential desiccation cracks. These regions are mostly within Noachian-aged terrains and are closely associated with phyllosilicate occurrences and smectites in particular. We have built a laboratory setup that allows us to carry out desiccation experiments on Mars-analog materials in an effort to constrain the physical and chemical properties of sediments that display polygonal cracks. The setup is complemented by a pre-existing simulation chamber that enables the investigation of the spectral and photometric properties of analog materials in Mars-like conditions. The initial experiments that have been carried out show that (1) crack patterns are visible in smectite-bearing materials in varying concentrations down to ~10% smectite by weight, (2) chlorides, and potentially other salts, delay the onset of cracking and may even block it from occurring entirely, and (3) the polygonal patterns, while being indicative of the presence of phyllosilicates, cannot be used to differentiate between various phyllosilicate-bearing deposits. However, their size-scale and morphology yields important information regarding their thickness and the hydrological conditions at the time of formation. Furthermore, the complementary spectral measurements for some of the analog samples shows that crack patterns may develop in materials with such low concentrations of smectites that would not be expected to be identified using remote-sensing instruments. This may explain the presence of polygonal patterns on Mars in sediments that lack spectral confirmation of phyllosilicates.

  10. Bifunctional electrodes for unitised regenerative fuel cells

    Microsoft Academic Search

    Sebastian Altmann; Till Kaz; Kaspar Andreas Friedrich

    2011-01-01

    The effects of different configurations and compositions of platinum and iridium oxide electrodes for the oxygen reaction of unitised regenerative fuel cells (URFC) are reported. Bifunctional oxygen electrodes are important for URFC development because favourable properties for the fuel cell and the electrolysis modes must be combined into a single electrode. The bifunctional electrodes were studied under different combinations of

  11. Episomal High Copy Number Maintenance of Hairpin-capped DNA Bearing a Replication Initiation Region in Human Cells*

    PubMed Central

    Harada, Seiyu; Uchida, Masafumi; Shimizu, Noriaki

    2009-01-01

    We previously found that a plasmid bearing a replication initiation region efficiently initiates gene amplification in mammalian cells and that it generates extrachromosomal double minutes and/or chromosomal homogeneously staining regions. During analysis of the underlying mechanism, we serendipitously found that hairpin-capped linear DNA was stably maintained as numerous extrachromosomal tiny episomes for more than a few months in a human cancer cell line. Generation of such episomes depended on the presence of the replication initiation region in the original plasmid. Despite extrachromosomal maintenance, episomal gene expression was epigenetically suppressed. The Southern blot analysis of the DNA of cloned cells revealed that the region around the hairpin end was diversified between the clones. Furthermore, the bisulfite-modified PCR and the sequencing analyses revealed that the palindrome sequence that derived from the original hairpin end or its end-resected structure were well preserved during clonal long term growth. From these data, we propose a model that explains the formation and maintenance of these episomes, in which replication of the hairpin-capped DNA and cruciform formation and its resolution play central roles. Our findings may be relevant for the dissection of mammalian replicator sequences. PMID:19617622

  12. Sonochemical Preparation of a Nanostructured Bifunctional Catalyst

    E-print Network

    Suslick, Kenneth S.

    report here a simple sonochemical preparation of a bifunctional "eggshell" catalyst for the conversion the oxide support onto which the clusters attach.12 This inherently generates "eggshell catalysts" where

  13. Tailored bifunctional polymer for plutonium monitoring.

    PubMed

    Paul, Sumana; Pandey, Ashok K; Kumar, Pranaw; Kaity, Santu; Aggarwal, Suresh K

    2014-07-01

    Monitoring of actinides with sophisticated conventional methods is affected by matrix interferences, spectral interferences, isobaric interferences, polyatomic interferences, and abundance sensitivity problems. To circumvent these limitations, a self-supported disk and membrane-supported bifunctional polymer were tailored in the present work for acidity-dependent selectivity toward Pu(IV). The bifunctional polymer was found to be better than the polymer containing either a phosphate group or a sulfonic acid group in terms of (i) higher Pu(IV) sorption efficiency at 3-4 mol L(-1) HNO3, (ii) selective preconcentration of Pu(IV) in the presence of a trivalent actinide such as Am(III), and (iii) preferential sorption of Pu(IV) in the presence of a large excess of U(VI). The bifunctional polymer was formed as a self-supported matrix by bulk polymerization and also as a 1-2 ?m thin layer anchored on a microporous poly(ether sulfone) by surface grafting. The proportions of sulfonic acid and phosphate groups in both the self-supported disk and membrane-supported bifunctional polymer were found to be the same as expected from the mole proportions of monomers in polymerizing solutions used for syntheses. ? radiography by a solid-state nuclear track detector indicated fairly homogeneous anchoring of the bifunctional polymer on the surface of the membrane. Pu(IV) preconcentrated on a single bifunctional bead was used for determination of the Pu isotopic composition by thermal ionization mass spectrometry. The membrane-supported bifunctional polymer was used for preconcentration and subsequent quantification of Pu(IV) by ? spectrometry using the absolute efficiency at a fixed counting geometry. The analytical performance of the membrane-supported-bifunctional-polymer-based ? spectrometry method was found to be highly reproducible for assay of Pu(IV) in a variety of complex samples. PMID:24901969

  14. A bifunctional nanocarrier based on amphiphilic hyperbranched polyglycerol derivatives

    E-print Network

    Peters, Achim

    A bifunctional nanocarrier based on amphiphilic hyperbranched polyglycerol derivatives Indah N here report on the synthesis of a bifunctional nanocarrier system based on amphiphilic hyperbranched treatment. Introduction Nanocarrier systems based on amphiphilic macromolecules for drug delivery have

  15. Contrast-enhanced MRI-guided photodynamic cancer therapy with a pegylated bifunctional polymer conjugate

    PubMed Central

    Vaidya, Anagha; Sun, Yongen; Feng, Yi; Emerson, Lyska; Jeong, Eun-Kee; Lu, Zheng-Rong

    2008-01-01

    Purpose To study contrast-enhanced MRI guided photodynamic therapy with a pegylated bifunctional polymer conjugate containing an MRI contrast agent and a photosensitizer for minimally invasive image-guided cancer treatment. Methods Pegylated and non-pegylated poly-(L-glutamic acid) conjugates containing mesochlorin e6, a photosensitizer, and Gd(III)-DO3A, an MRI contrast agent, were synthesized. The effect of pegylation on the biodistribution and tumor targeting was non-invasively visualized in mice bearing MDA-MB-231 tumor xenografts with MRI. MRI-guided photodynamic therapy was carried out in the tumor bearing mice. Tumor response to photodynamic therapy was evaluated by dynamic contrast enhanced MRI and histological analysis. Results The pegylated conjugate had longer blood circulation, lower liver uptake and higher tumor accumulation than the non-pegylated conjugate as shown by MRI. Site-directed laser irradiation of tumors resulted in higher therapeutic efficacy for the pegylated conjugate than the non-pegylated conjugate. Moreover, animals treated with photodynamic therapy showed reduced vascular permeability on DCE-MRI and decreased microvessel density in histological analysis. Conclusions Pegylation of the polymer bifunctional conjugates reduced non-specific liver uptake and increased tumor uptake, resulting in significant tumor contrast enhancement and high therapeutic efficacy. The pegylated poly(L-glutamic acid) bifunctional conjugate is promising for contrast enhanced MRI guided photodynamic therapy in cancer treatment. PMID:18584312

  16. Biochemical and Structural Characterization of the Arabidopsis Bifunctional Enzyme Dethiobiotin

    E-print Network

    Paris-Sud XI, Université de

    Biochemical and Structural Characterization of the Arabidopsis Bifunctional Enzyme Dethiobiotin by a single enzyme encoded by a bifunctional gene originating from the fusion of prokaryotic monofunctional of a bifunctional enzyme in biotin synthesis pathway in eukaryotes and the relative implication of each

  17. Synthesis and evaluation of bifunctional chelating agents derived from bis(2-aminophenylthio)alkane for radioimaging with 99mTc

    Microsoft Academic Search

    Bhupender S. Chhikara; Nitin Kumar; Vibha Tandon; Anil K. Mishra

    2005-01-01

    Novel bifunctional chelating agents bearing an aromatic rigid backbone have been synthesized and characterized on the basis of spectroscopic techniques. These macrocyclic multidentate chelating agents were conjugated with monoclonal antibody which forms stable complexes with 99mTc with high radiochemical purity.

  18. Bifunctional nanoparticles with magnetism and NIR fluorescence: controlled synthesis from combination of AGET ATRP and ‘click’ reaction

    NASA Astrophysics Data System (ADS)

    He, Weiwei; Cheng, Liang; Zhang, Lifen; Jiang, Xiaowu; Liu, Zhuang; Cheng, Zhenping; Zhu, Xiulin

    2014-01-01

    In this work, bifunctional nanoparticles (NPs) capable of emitting near infrared (NIR) fluorescence and generating superparamagnetism under an external magnetic field were prepared by combination of ‘click’ reaction and surface-initiated activators generated by electron transfer for atom transfer radical polymerization (AGET ATRP) of water-soluble poly(ethylene glycol) monomethyl ether methacrylate (PEGMA) and glycidyl methacrylate (GMA) using biocompatible iron as the catalyst on the surface of silica-coated iron oxide (Fe3O4@SiO2) NPs. The nanosized Fe3O4@SiO2@PPEGMA-co-PGMA@N3 was prepared through AGET ATRP and alkynyl bearing NIR dye was also prepared; afterwards they were integrated together by ‘click’ reaction. The different stages of surface modification were approved by employing different characterization techniques such as TEM, XRD, XPS, VSM and FT-IR, and the properties of the final NPs were thoroughly studied. Their suitability as dual model imaging agents for magnetic resonance (MR) and fluorescence imaging was investigated, indicating them to be a competitive candidate for imaging contrast agents.

  19. Polar Bears

    NSDL National Science Digital Library

    Mr. Thomas

    2010-09-27

    Use the following websites to answer questions about the rapid disappearance of polar bears in the Arctic region. Polar Bear picture Polar Bear Tracker 1: What region in the world has the fewest polar bears? 2: Using the internet as a resource, provide some reasons as to why this region is suffering from the most polar bear differences? Polar Bears Change Diet 1: Why are polar bears having to change their diets? 2: List some other factors (besides diet) in the ...

  20. Bearing system

    DOEpatents

    Kapich, Davorin D. (Carlsbad, CA)

    1987-01-01

    A bearing system includes backup bearings for supporting a rotating shaft upon failure of primary bearings. In the preferred embodiment, the backup bearings are rolling element bearings having their rolling elements disposed out of contact with their associated respective inner races during normal functioning of the primary bearings. Displacement detection sensors are provided for detecting displacement of the shaft upon failure of the primary bearings. Upon detection of the failure of the primary bearings, the rolling elements and inner races of the backup bearings are brought into mutual contact by axial displacement of the shaft.

  1. Lysine degradation through the saccharopine pathway in mammals: involvement of both bifunctional and monofunctional lysine-degrading enzymes in mouse.

    PubMed Central

    Papes, F; Kemper, E L; Cord-Neto, G; Langone, F; Arruda, P

    1999-01-01

    Lysine-oxoglutarate reductase and saccharopine dehydrogenase are enzymic activities that catalyse the first two steps of lysine degradation through the saccharopine pathway in upper eukaryotes. This paper describes the isolation and characterization of a cDNA clone encoding a bifunctional enzyme bearing domains corresponding to these two enzymic activities. We partly purified those activities from mouse liver and showed for the first time that both a bifunctional lysine-oxoglutarate reductase/saccharopine dehydrogenase and a monofunctional saccharopine dehydrogenase are likely to be present in this organ. Northern analyses indicate the existence of two mRNA species in liver and kidney. The longest molecule, 3.4 kb in size, corresponds to the isolated cDNA and encodes the bifunctional enzyme. The 2.4 kb short transcript probably codes for the monofunctional dehydrogenase. Sequence analyses show that the bifunctional enzyme is likely to be a mitochondrial protein. Furthermore, enzymic and expression analyses suggest that lysine-oxoglutarate reductase/saccharopine dehydrogenase levels increase in livers of mice under starvation. Lysine-injected mice also show an increase in lysine-oxoglutarate reductase and saccharopine dehydrogenase levels. PMID:10567240

  2. Bear Spray Safety Program

    USGS Publications Warehouse

    Blome, C.D.; Kuzniar, R.L.

    2009-01-01

    A bear spray safety program for the U.S. Geological Survey (USGS) was officially initiated by the Firearms Safety Committee to address accident prevention and to promote personnel training in bear spray and its transportation, storage, and use for defense against wild animals. Used as part of a system including firearms, or used alone for those who choose not to carry a firearm, bear spray is recognized as an effective tool that can prevent injury in a wild animal attack.

  3. Polar Bear Polar Bear

    NSDL National Science Digital Library

    Kelly Burgess

    2012-09-11

    In this lesson, students will listen for key details in a nonfiction text about polar bears. They will work at completing a graphic organizer with the teacher to help organize their thinking and understanding of key details about a text. They will also complete an independent assignment where they will draw or write two things that they learned about the topic.

  4. Immunohistochemistry for a bifunctional protein in patients with peroxisomal disorders

    Microsoft Academic Search

    Atsushi Imamura; Atsushi Kamei; Yasuyuki Suzuki; Naomi Kondo; Tadao Orii; Sachio Takashima

    1995-01-01

    Immunohistochemical studies using antisera against bifunctional protein, a ?-oxidation enzyme, were performed on liver, kidney, and brain tissue specimens from patients with peroxisomal disorders and from controls to investigate the distribution and development of peroxisomes. Bifunctional protein-positive granules were not found in patients with Zellweger syndrome or neonatal adrenoleukodystrophy, whereas positive immunoreactivity was observed from 8 and 6 weeks gestation

  5. Bifunctional Asymmetric Catalysis: Cooperative Lewis Acid/Base Systems

    E-print Network

    Lectka, Thomas

    Bifunctional Asymmetric Catalysis: Cooperative Lewis Acid/Base Systems DANIEL H. PAULL, CIBY J with the Lewis base or with the nucleophilic SCHEME 1. Bifunctional Lewis Acid/Base (LA/LB) Catalysis Vol. 41, No acid and a "soft" Lewis base (using Pearson's terminology) may allevi- ate the problem of catalyst

  6. IL12 initiates tumor rejection via lymphoid tissue–inducer cells bearing the natural cytotoxicity receptor NKp46

    Microsoft Academic Search

    Maya Eisenring; Johannes vom Berg; Glen Kristiansen; Elisabeth Saller; Burkhard Becher

    2010-01-01

    The potent tumoricidal activity of interleukin 12 (IL-12) is thought to be mediated by the activation and polarization of natural killer (NK) cells and T helper type 1 (TH1) cells, respectively. By systematic analysis of the IL-12-induced immune response to subcutaneous melanoma (B16), we found that tumor suppression was mediated independently of T lymphocytes or NK cells. IL-12 initiated local

  7. An enzymatic approach to bifunctional chelating agents.

    PubMed

    Minazzi, Paolo; Lattuada, Luciano; Menegotto, Ivan G; Giovenzana, Giovanni B

    2014-09-21

    Bifunctional chelating agents (BFCAs) combine the complexing properties of a multidentate ligand with the presence of a free reactive functional group, mainly devoted to conjugation purposes. Indeed, products obtained by conjugation of a BFCA to a biomolecule and coordination of a suitable metal ion are widely applied in medicine nowadays as diagnostic and therapeutic agents. BFCAs are generally prepared through multi-step syntheses and with extensive application of protection-deprotection strategies, due to the large number of functional groups involved. Hydrolytic enzymes, with their unique chemoselectivity, provided the best results in the preparation of three different BFCAs based on very useful and well known ligand platforms. PMID:25060174

  8. Bifunctional bacterial magnetic nanoparticles for tumor targeting

    NASA Astrophysics Data System (ADS)

    Guo, Lin; Huang, Ji; Zheng, Li-Min

    2012-01-01

    Bifunctional bacterial magnetic nanoparticles (BBMPs), which present both magnetic drug targeting and tumor bio-targeting properties, have been developed by chemically coupling both doxorubicin and a galactosyl ligand on to the membrane surface of the bacterial magnetic nanoparticles (BMPs). The BBMP product has a high drug load ratio and magnetic respondence, and exhibits a narrow size distribution and is sensitive to pH to enable drug release. In comparison to doxorubicin-coupled BMPs, without modification with a galactosyl ligand, BBMPs present a higher uptake by the target asialoglycoprotein receptor (ASGP-R) expressed by HepG2 cells and display stronger cytotoxicity.

  9. Analysis of Bearing Incidents in Aircraft Gas Turbine Mainshaft Bearings

    Microsoft Academic Search

    B. L. Averbach; E. N. Bamberger

    1991-01-01

    An examination of approximately 200 bearing incidents in current aircraft engines has shown that damage in the bearing is initiated at the surface. Twenty-one cases were studied in detail, and five typical incidents are presented here. The initial damage was produced by abrasive particles, dents, grinding scores, skidding, large carbides and corrosion pits. The first phase of the failure mechanism

  10. Bearing fatigue investigation 3

    NASA Technical Reports Server (NTRS)

    Nahm, A. H.; Bamberger, E. N.; Signer, H. R.

    1982-01-01

    The operating characteristics of large diameter rolling-element bearings in the ultra high speed regimes expected in advanced turbine engines for high performance aircraft were investigated. A high temperature lubricant, DuPont Krytox 143 AC, was evaluated at bearing speeds to 3 million DN. Compared to the results of earlier, similar tests using a MIL-L-23699 (Type II) lubricant, bearings lubricated with the high density Krytox fluid showed significantly higher power requirements. Additionally, short bearing lives were observed when this fluid was used with AISI M50 bearings in an air atmosphere. The primary mode of failure was corrosion initiated surface distress (fatigue) on the raceways. The potential of a case-carburized bearing to sustain a combination of high-tangential and hertzian stresses without experiencing race fracture was also investigated. Limited full scale bearing tests of a 120 mm bore ball bearing at a speed of 25,000 rpm (3 million DN) indicated that a carburized material could sustain spalling fatigue without subsequent propagation to fracture. Planned life tests of the carburized material had to be aborted, however, because of apparent processing-induced material defects.

  11. Bifunctional transition metal-based molecular catalysts for asymmetric syntheses

    Microsoft Academic Search

    Takao Ikariya; Kunihiko Murata; Ryoji Noyori

    2006-01-01

    The discovery and development of conceptually new chiral bifunctional transition metal-based catalysts for asymmetric reactions is described. The chiral bifunctional Ru catalyst was originally developed for asymmetric transfer hydrogenation of ketones and imines and is now successfully applicable to enantioselective C-C bond formation reaction with a wide scope and high practicability. The deprotonation of 1,3-dicarbonyl compounds with the chiral amido

  12. Stereogenic-at-Metal Zn- and Al-based N-Heterocyclic Carbene (NHC) Complexes as Bifunctional Catalysts in Cu-Free Enantioselective Allylic Alkylations

    PubMed Central

    Lee, Yunmi; Li, Bo; Hoveyda, Amir H.

    2009-01-01

    Investigations detailed herein demonstrate the ability of chiral bidentate N-heterocyclic carbenes to promote directly – without the need for a Cu salt – site- and enantioselective C–C bond forming reactions. Within this context, catalytic allylic alkylations of various allylic phosphates with dialkylzinc and trialkylaluminum reagents, performed with chiral bidentate imidazolinium salts and in the absence of a Cu salt, are described. The Cu-free transformations deliver products bearing tertiary or (all-carbon) quaternary stereogenic centers with exceptional site- (>98:<2 SN2?:SN2) and high enantioselectivity [up to 97.5:2.5 enantiomer ratio (er)]. A chiral Zn-based N-heterocyclic carbene (NHC) complex, which serves as the catalyst for the enantioselective allylic alkylation reactions, is isolated and fully characterized. Spectroscopic and X-ray crystallographic studies indicate that the sulfonate group within the stereogenic-at-Zn bidentate complexes coordinates syn to the proximal phenyl substituent of the NHC backbone (vs the initially expected anti). Investigations regarding a related chiral NHC–Al based complex reveal similar structural attributes. The studies outlined provide a plausible rationale regarding the mechanism of Cu-free allylic alkylation reactions that involve dialkylzinc or trialkylaluminum reagents as well as the previously reported alkylmagnesium halides. Based on the research disclosed, it is proposed that bidentate metal-carbene complexes can serve as effective bifunctional catalysts, a critical attribute that differentiates such NHC-based complexes from the corresponding monodentate variants. PMID:19630406

  13. Hybrid Bearing Prognostic Test Rig

    NASA Technical Reports Server (NTRS)

    Dempsey, Paula J.; Certo, Joseph M.; Handschuh, Robert F.; Dimofte, Florin

    2005-01-01

    The NASA Glenn Research Center has developed a new Hybrid Bearing Prognostic Test Rig to evaluate the performance of sensors and algorithms in predicting failures of rolling element bearings for aeronautics and space applications. The failure progression of both conventional and hybrid (ceramic rolling elements, metal races) bearings can be tested from fault initiation to total failure. The effects of different lubricants on bearing life can also be evaluated. Test conditions monitored and recorded during the test include load, oil temperature, vibration, and oil debris. New diagnostic research instrumentation will also be evaluated for hybrid bearing damage detection. This paper summarizes the capabilities of this new test rig.

  14. An Efficient Bifunctional Decadentate Ligand 3p-C-DEPA for Targeted Alpha Radioimmunotherapy Applications

    PubMed Central

    Song, Hyun A; Kang, Chi Soo; Baidoo, Kwamena E.; Milenic, Diane E.; Chen, Yunwei; Dai, Anzhi; Brechbiel, M. W.; Chong, Hyun-Soon

    2011-01-01

    A new bifunctional ligand 3p-C-DEPA was synthesized and evaluated for use in targeted alpha radioimmunotherapy. 3p-C-DEPA was efficiently prepared via regiospecific ring opening of an aziridinium ion and conjugated with trastuzumab. The 3p-C-DEPA-trastuzumab conjugate was extremely rapid in binding 205/6Bi, and the corresponding 205/6Bi-3p-C-DEPA-trastuzumab complex was stable in human serum. Biodistribution studies were performed to evaluate in vivo stability and tumor targeting of 205/6Bi-3p-C-DEPA-trastuzumab conjugate in tumor bearing athymic mice. 205/6Bi-3p-C-DEPA-trastuzumab conjugate displayed excellent in vivo stability and targeting as evidenced by low organ uptake and high tumor uptake. The results of the in vitro and in vivo studies indicate that 3p-C-DEPA is a promising chelator for radioimmunotherapy of 212Bi and 213Bi. PMID:21604692

  15. Bearing Cartridge Designed To Reduce Wear

    NASA Technical Reports Server (NTRS)

    Krieg, Eric J.

    1992-01-01

    Bearing cartridge holding outer races of two ball bearings in turbopump designed to prevent unloading of bearings during operating transients. Cartridge and bearings replace two ball bearings, whose outer races mounted in cylinder called "isolator" and preloaded by single spring mount holding isolator and reacting radial loads. Cartridge slides axially in bore of isolator during transients and forces outer races to move as pair. Necessary to eliminate unloading because unloading initiates wear.

  16. Foil bearings

    Microsoft Academic Search

    David A. Elrod

    1993-01-01

    The rolling element bearings (REB's) which support many turbomachinery rotors offer high load capacity, low power requirements, and durability. Two disadvantages of REB's are: (1) rolling or sliding contact within the bearing has life-limiting consequences; and (2) REB's provide essentially no damping. The REB's in the Space Shuttle Main Engine (SSME) turbopumps must sustain high static and dynamic loads, at

  17. Polar Bear

    USGS Publications Warehouse

    Amstrup, S.D.; DeMaster

    1988-01-01

    Polar bears are long-lived, late-maturing carnivores that have relatively low rates of reproduction and natural mortality. Their populations are susceptible to disturbance from human activities, such as the exploration and development of mineral resources or hunting. Polar bear populations have been an important renewable resource available to coastal communities throughout the Arctic for thousands of years.

  18. Designing bifunctional NOP receptor-mu opioid receptor ligands from NOP receptor-selective scaffolds. Part I.

    PubMed

    Zaveri, Nurulain T; Jiang, Faming; Olsen, Cris; Polgar, Willma E; Toll, Lawrence

    2013-06-01

    The nociceptin receptor (NOP) and its endogenous agonist, nociceptin/orphanin FQ (N/OFQ), members of the opioid receptor and peptide families respectively, modulate the pharmacological effects of classical opioids, particularly opioid-induced reward and nociception. We hypothesized that compounds containing both NOP and opioid receptor activity in a single molecule may have useful pharmacological profiles as non-addicting analgesics or as drug abuse medications. We report here our forays into the structure-activity relationships for discovering 'bifunctional' NOP-mu opioid receptor (MOP) ligands, starting from our NOP-selective scaffolds. This initial SAR suggests pharmacophoric elements that may be modified to modulate/increase opioid affinity, while maintaining high affinity for the NOP receptor, to result in potent bifunctional small-molecule NOP/MOP ligands. PMID:23623415

  19. Designing Bifunctional NOP receptor-mu opioid receptor ligands from NOP receptor-selective scaffolds. Part I

    PubMed Central

    Zaveri, Nurulain; Jiang, Faming; Olsen, Cris; Polgar, Willma; Toll, Lawrence

    2013-01-01

    The nociceptin receptor (NOP) and its endogenous agonist, nociceptin/Orphanin FQ (N/OFQ), members of the opioid receptor and peptide families respectively, modulate the pharmacological effects of classical opioids, particularly opioid-induced reward and nociception. We hypothesized that compounds containing both NOP and opioid receptor activity in a single molecule may have useful pharmacological profiles as non-addicting analgesics or as drug abuse medications. We report here our forays into the structure-activity relationships for discovering `bifunctional' NOP-mu opioid receptor (MOP) ligands, starting from our NOP-selective scaffolds. This initial SAR suggests pharmacophoric elements that may be modified to modulate/increase opioid affinity, while maintaining high affinity for the NOP receptor, to result in potent bifunctional small-molecule NOP/MOP ligands. PMID:23623415

  20. Magnetic Bearing

    NASA Technical Reports Server (NTRS)

    1996-01-01

    AVCON, Inc. produces advanced magnetic bearing systems for industrial use, offering a unique technological approach based on contract work done at Marshall Space Flight Center and Lewis Research Center. Designed for the turbopump of the Space Shuttle main engine, they are now used in applications such as electric power generation, petroleum refining, machine tool operation and natural gas pipelines. Magnetic bearings support moving machinery without physical contact; AVCON's homopolar approach is a hybrid of permanent and electromagnets which are one-third the weight, smaller and more power- efficient than previous magnetic bearings.

  1. Polar Bear

    NSDL National Science Digital Library

    2009-01-01

    In this episode of the Podcast of Life, host Ari Daniel Shapiro relates two close calls with polar bears. Listen as Heather Cray recalls how, dumped by a storm on a small Arctic island without a shotgun, she got an unexpected wake-up call. And when researcher Steve Amstrup accidentally crashed through the roof of a polar bear’s den, no one could predict what happened next. Also included is a Learn More section that provides background information on the scientists recorded in the podcast, lessons, images, and cool facts.

  2. Bobbie Bear

    NSDL National Science Digital Library

    Illuminations National Council of Teachers of Mathematics

    2009-03-06

    Using a virtual manipulative, children construct combinations of different colored shirts and pants to help Bobbie Bear, who is planning a vacation and wants to know how many different outfits he will be able to make from these combinations.

  3. Foil bearings

    NASA Technical Reports Server (NTRS)

    Elrod, David A.

    1993-01-01

    The rolling element bearings (REB's) which support many turbomachinery rotors offer high load capacity, low power requirements, and durability. Two disadvantages of REB's are: (1) rolling or sliding contact within the bearing has life-limiting consequences; and (2) REB's provide essentially no damping. The REB's in the Space Shuttle Main Engine (SSME) turbopumps must sustain high static and dynamic loads, at high speeds, with a cryogenic fluid as lubricant and coolant. The pump end ball bearings limit the life of the SSME high pressure oxygen turbopump (HPOTP). Compliant foil bearing (CFB) manufacturers have proposed replacing turbopump REB's with CFB's CFB's work well in aircraft air cycle machines, auxiliary power units, and refrigeration compressors. In a CFB, the rotor only contracts the foil support structure during start up and shut down. CFB damping is higher than REB damping. However, the load capacity of the CFB is low, compared to a REB. Furthermore, little stiffness and damping data exists for the CFB. A rotordynamic analysis for turbomachinery critical speeds and stability requires the input of bearing stiffness and damping coefficients. The two basic types of CFB are the tension-dominated bearing and the bending-dominated bearing. Many investigators have analyzed and measured characteristics of tension-dominated foil bearings, which are applied principally in magnetic tape recording. The bending-dominated CFB is used more in rotating machinery. This report describes the first phase of a structural analysis of a bending-dominated, multileaf CFB. A brief discussion of CFB literature is followed by a description and results of the present analysis.

  4. Structural basis for bifunctional peptide recognition at human ?-opioid receptor.

    PubMed

    Fenalti, Gustavo; Zatsepin, Nadia A; Betti, Cecilia; Giguere, Patrick; Han, Gye Won; Ishchenko, Andrii; Liu, Wei; Guillemyn, Karel; Zhang, Haitao; James, Daniel; Wang, Dingjie; Weierstall, Uwe; Spence, John C H; Boutet, Sébastien; Messerschmidt, Marc; Williams, Garth J; Gati, Cornelius; Yefanov, Oleksandr M; White, Thomas A; Oberthuer, Dominik; Metz, Markus; Yoon, Chun Hong; Barty, Anton; Chapman, Henry N; Basu, Shibom; Coe, Jesse; Conrad, Chelsie E; Fromme, Raimund; Fromme, Petra; Tourwé, Dirk; Schiller, Peter W; Roth, Bryan L; Ballet, Steven; Katritch, Vsevolod; Stevens, Raymond C; Cherezov, Vadim

    2015-03-01

    Bifunctional ?- and ?-opioid receptor (OR) ligands are potential therapeutic alternatives, with diminished side effects, to alkaloid opiate analgesics. We solved the structure of human ?-OR bound to the bifunctional ?-OR antagonist and ?-OR agonist tetrapeptide H-Dmt-Tic-Phe-Phe-NH2 (DIPP-NH2) by serial femtosecond crystallography, revealing a cis-peptide bond between H-Dmt and Tic. The observed receptor-peptide interactions are critical for understanding of the pharmacological profiles of opioid peptides and for development of improved analgesics. PMID:25686086

  5. Bifunctional Chelates Optimized for Molecular MRI

    PubMed Central

    2015-01-01

    Important requirements for exogenous dyes or contrast agents in magnetic resonance imaging (MRI) include an effective concentration of paramagnetic or superparamagnetic ions at the target to be imaged. We report the concise synthesis and characterization of several new enantiopure bifunctional derivatives of (?1R,?4R,?7R,?10R)-?1,?4,?7,?10-tetramethyl-1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTMA) (and their 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA) analogues as controls) that can be covalently attached to a contrast agent delivery system using either click or peptide coupling chemistry. Gd complexes of these derivatives can be attached to delivery systems while maintaining optimal water residence time for increased molecular imaging sensitivity. Long chain biotin (LC-biotin) derivatives of the Eu(III) and Gd(III) chelates associated with avidin are used to demonstrate higher efficiencies. Variable-temperature relaxometry, 17O NMR, and nuclear magnetic resonance dispersion (NMRD) spectroscopy used on the complexes and biotin–avidin adducts measure the influence of water residence time and rotational correlation time on constrained and unconstrained systems. The Gd(III)-DOTMA derivative has a shorter water residence time than the Gd(III)-DOTA derivative. Compared to the constrained Gd(III)-DOTA derivatives, the rotationally constrained Gd(III)-DOTMA derivative has ?40% higher relaxivity at 37 °C, which could increase its sensitivity as an MRI agent as well as reduce the dose of the targeting agent. PMID:24933389

  6. Cave Bear

    NSDL National Science Digital Library

    American Association for the Advancement of Science (; )

    2005-08-15

    Decoding an ancient cave bear. A two-ton, thirteen-foot cave bear, extinct for ten thousand years, has just experienced a rebirth of sorts. From a tooth and a bone, scientists have recovered its entire genetic code.Eddy Rubin, director of the Department of Energy's Joint Genome Institute, says finding genuine cave bear DNA was like looking for a needle in a haystack. The haystack were all the other organisms that were living in the bones and in the tooth of this ancient creature. And the needle was the little bit of the ancient creature's genome DNA, or genes.They used state-of-the-art computer technology to separate the bear genes from the clutter. Jurassic Park fans should note that they can't clone a new cave bear, nor can they recover DNA from creatures as old as the dinosaurs. But they do hope to reconstruct the genetic code of Neanderthals, our closest non-human relatives, to better understand how our own species evolved. This resource contains detailed text description of the research as well as likes for further inquiry.

  7. A novel bifunctional electrocatalyst for unitized regenerative fuel cell

    Microsoft Academic Search

    Yining Zhang; Huamin Zhang; Yuanwei Ma; Jinbin Cheng; Hexiang Zhong; Shidong Song; Haipeng Ma

    2010-01-01

    5wt.% of platinum (Pt) nanoparticles are highly dispersed on the surface of IrO2 by chemical reduction, and the catalyst is mixed with Pt black to be used as a novel bifunctional oxygen electrocatalyst for the unitized regenerative fuel cell (URFC). The novel cell has been evaluated in the hydrogen and oxygen fuel cell and water electrolysis modes, and compared to

  8. Synthesis of acrylic and allylic bifunctional cross-linking monomers derived from PET waste

    NASA Astrophysics Data System (ADS)

    Cruz-Aguilar, A.; Herrera-González, A. M.; Vázquez-García, R. A.; Navarro-Rodríguez, D.; Coreño, J.

    2013-06-01

    An acrylic and two novel allylic monomers synthesized from bis (hydroxyethyl) terephthalate, BHET, are reported. This was obtained by glycolysis of post-consumer PET with boiling ethylene glycol. The bifunctional monomer bis(2-(acryloyloxy)ethyl) terephthalate was obtained from acryloyl chloride, while the allylic monomers 2-(((allyloxi)carbonyl)oxy) ethyl (2-hydroxyethyl) terephthalate and bis(2-(((allyloxi)carbonyl)oxy)ethyl) terephthalate, from allyl chloroformate. Cross-linking was studied in bulk polymerization using two different thermal initiators. Monomers were analyzed by means of 1H NMR and the cross-linked polymers by infrared spectroscopy. Gel content higher than 90% was obtained for the acrylic monomer. In the case of the mixture of the allylic monomers, the cross-linked polymer was 80 % using BPO initiator, being this mixture 24 times less reactive than the acrylic monomer.

  9. Predicting bearing states in three dimensions

    E-print Network

    D. V. Stäger; N. A. M. Araújo; H. J. Herrmann

    2015-05-27

    Bichromatic bearings have an infinite number of sliding-free states, so called bearing states. For three-dimensional bichromatic bearings whose bearing states have four degrees of freedom, we show how the bearing state can be analytically predicted from the initial state without any information about the nature of the contact forces. We provide a systematic way of constructing such bearings and also show how the bearing state is modified by blocking a single sphere and that any bearing state can be induced by controlling the angular velocities of only two spheres. Furthermore, we show that it is possible to determine the total mass and the center of mass of the bearing by analyzing its response to changes of the angular velocities of at most two spheres.

  10. Bear Bones

    NSDL National Science Digital Library

    Science Update

    2004-03-08

    An estimated ten million Americans have osteoporosis, an age-related disease in which the bones gradually become brittle and weak. Now, scientists are looking to animals for clues on how to combat this condition. This resource describes the study of sustaining bone strength of hibernating bears.

  11. Availability of ground water for large-scale use in the Malad Valley-Bear River areas of southeastern Idaho: an initial assessment

    USGS Publications Warehouse

    Burnham, W.L.; Harder, A.H.; Dion, N.P.

    1969-01-01

    Five areas within the Bear River drainage of southeastern Idaho offer potential for further development of ground water--the valley north of Bear Lake, north of Soda Springs, Gem Valley, Cache Valley in Idaho, and Malad Valley in Idaho. Saturated deposits north of Bear Lake are too fine-textured to yield large quantities to wells; the areas north of Soda Springs and in Gem Valley would provide large yields, but at the expense of current beneficial discharge. Northern Cache Valley has small areas of high yield in the northwestern part, but total annual yield would be only about 20,000 acre-feet and seasonal water-level fluctuation would be large. Malad Valley contains a large aquifer system within valley fill underlying about 75 square miles. The aquifer system is several hundred feet thick, and contains about 1.8 million acre-feet of water in storage in the top 300 feet of saturated thickness. Average annual recharge to the valley-fill aquifer is about 64,000 acre-feet. Lowering of the water level 100 feet uniformly over the valley area would theoretically yield about 300,000 acre-feet from storage and salvage a present-day large nonbeneficial discharge. Sufficient water to irrigate all lands in a planned project near Samaria could be pumped with a maximum 200-foot pumping lift and then delivered by gravity flow. Such pumping would cause water-level lowering of a few feet to a few tens of feet in present artesian areas, and would cause many present-day artesian wells to cease flowing at land surface. Chemical-quality problems in Malad Valley seem not to be sufficient to prohibit development and use of the ground-water resource.

  12. System for testing bearings

    NASA Technical Reports Server (NTRS)

    Gibson, John C. (inventor)

    1993-01-01

    Disclosed here is a system for testing bearings wherein a pair of spaced bearings provides support for a shaft on which is mounted a bearing to be tested, this bearing being mounted in a bearing holder spaced from and in alignment with the pair of bearings. The bearing holder is provided with an annular collar positioned in an opening in the bearing holder for holding the bearing to be tested. A screw threaded through the bearing holder into engagement with the annular collar can be turned to force the collar radially out of alignment with the pair of bearings to apply a radial load to the bearing.

  13. Improving battery safety by early detection of internal shorting with a bifunctional separator

    NASA Astrophysics Data System (ADS)

    Wu, Hui; Zhuo, Denys; Kong, Desheng; Cui, Yi

    2014-10-01

    Lithium-based rechargeable batteries have been widely used in portable electronics and show great promise for emerging applications in transportation and wind–solar-grid energy storage, although their safety remains a practical concern. Failures in the form of fire and explosion can be initiated by internal short circuits associated with lithium dendrite formation during cycling. Here we report a new strategy for improving safety by designing a smart battery that allows internal battery health to be monitored in situ. Specifically, we achieve early detection of lithium dendrites inside batteries through a bifunctional separator, which offers a third sensing terminal in addition to the cathode and anode. The sensing terminal provides unique signals in the form of a pronounced voltage change, indicating imminent penetration of dendrites through the separator. This detection mechanism is highly sensitive, accurate and activated well in advance of shorting and can be applied to many types of batteries for improved safety.

  14. Bifunctional air electrodes containing elemental iron powder charging additive

    DOEpatents

    Liu, Chia-tsun (Monroeville, PA); Demczyk, Brian G. (Rostrover Township, Westmoreland County, PA); Gongaware, Paul R. (Penn Township, Westmoreland County, PA)

    1982-01-01

    A bifunctional air electrode for use in electrochemical energy cells is made, comprising a hydrophilic layer and a hydrophobic layer, where the hydrophilic layer essentially comprises a hydrophilic composite which includes: (i) carbon; (ii) elemental iron particles having a particle size of between about 25 microns and about 700 microns diameter; (iii) an oxygen evolution material; (iv) a nonwetting agent; and (v) a catalyst, where at least one current collector is formed into said composite.

  15. Topologically constrained bifunctional intercalators: DNA intercalation by a macrocyclic bisacridine

    Microsoft Academic Search

    Steven C. Zimmerman; Carol R. Lamberson; Michael Cory; Terri A. Fairley

    1989-01-01

    A topologically novel DNA bifunctional intercalator, 4, has been synthesized and its DNA binding compared with the binding of the monointercalator 9-aminoacridine (6) and spermine bisacridine (5), a known bisintercalator. Water-soluble macrocyclic bisacridine 4 was synthesized by reaction of 4-(bromomethyl)-9-~hloroacridine with N,N'-bis(2-mercapto- ethy1)succinamide and base. The resulting dichloride was converted to the corresponding bis(9-phenoxyacridine), which reacted with spermine tetrahydrochloride to

  16. Automated Assistance for Designing Active Magnetic Bearings

    NASA Technical Reports Server (NTRS)

    Imlach, Joseph

    2008-01-01

    MagBear12 is a computer code that assists in the design of radial, heteropolar active magnetic bearings (AMBs). MagBear12 was developed to help in designing the system described in "Advanced Active-Magnetic-Bearing Thrust-Measurement System". Beyond this initial application, MagBear12 is expected to be useful for designing AMBs for a variety of rotating machinery. This program incorporates design rules and governing equations that are also implemented in other, proprietary design software used by AMB manufacturers. In addition, this program incorporates an advanced unpublished fringing-magnetic-field model that increases accuracy beyond that offered by the other AMB-design software.

  17. Shadow enhancers enable Hunchback bifunctionality in the Drosophila embryo.

    PubMed

    Staller, Max V; Vincent, Ben J; Bragdon, Meghan D J; Lydiard-Martin, Tara; Wunderlich, Zeba; Estrada, Javier; DePace, Angela H

    2015-01-20

    Hunchback (Hb) is a bifunctional transcription factor that activates and represses distinct enhancers. Here, we investigate the hypothesis that Hb can activate and repress the same enhancer. Computational models predicted that Hb bifunctionally regulates the even-skipped (eve) stripe 3+7 enhancer (eve3+7) in Drosophila blastoderm embryos. We measured and modeled eve expression at cellular resolution under multiple genetic perturbations and found that the eve3+7 enhancer could not explain endogenous eve stripe 7 behavior. Instead, we found that eve stripe 7 is controlled by two enhancers: the canonical eve3+7 and a sequence encompassing the minimal eve stripe 2 enhancer (eve2+7). Hb bifunctionally regulates eve stripe 7, but it executes these two activities on different pieces of regulatory DNA--it activates the eve2+7 enhancer and represses the eve3+7 enhancer. These two "shadow enhancers" use different regulatory logic to create the same pattern. PMID:25564665

  18. Shadow enhancers enable Hunchback bifunctionality in the Drosophila embryo

    PubMed Central

    Staller, Max V.; Vincent, Ben J.; Bragdon, Meghan D. J.; Lydiard-Martin, Tara; Wunderlich, Zeba; Estrada, Javier; DePace, Angela H.

    2015-01-01

    Hunchback (Hb) is a bifunctional transcription factor that activates and represses distinct enhancers. Here, we investigate the hypothesis that Hb can activate and repress the same enhancer. Computational models predicted that Hb bifunctionally regulates the even-skipped (eve) stripe 3+7 enhancer (eve3+7) in Drosophila blastoderm embryos. We measured and modeled eve expression at cellular resolution under multiple genetic perturbations and found that the eve3+7 enhancer could not explain endogenous eve stripe 7 behavior. Instead, we found that eve stripe 7 is controlled by two enhancers: the canonical eve3+7 and a sequence encompassing the minimal eve stripe 2 enhancer (eve2+7). Hb bifunctionally regulates eve stripe 7, but it executes these two activities on different pieces of regulatory DNA—it activates the eve2+7 enhancer and represses the eve3+7 enhancer. These two “shadow enhancers” use different regulatory logic to create the same pattern. PMID:25564665

  19. 5790 J. Am. Chem. SOC.1987, 109, 5790-5800 Concerted General Base and Bifunctional General Acid

    E-print Network

    Cox, Michael M.

    5790 J. Am. Chem. SOC.1987, 109, 5790-5800 Concerted General Base and Bifunctional General Acid with pyrazole is catalyzed by general bases and by bifunctional general acids. The Br~lnstedplot for general of a significant lifetime for T'. Catalysis is observed with buffer acids when the acid is bifunctional. The rate

  20. Flex bearing UUEC, volume 2

    NASA Technical Reports Server (NTRS)

    Clapper, M. L.

    1993-01-01

    This volume, Volume 2, of this Flex Bearing UUEC Final Report documents findings and data pertaining to Team B's tasks. Team B was organized as one of two sub-teams of the Unplanned/Unintended Event or Condition (UUEC) board established per InterOffice Memorandum (IOM) A100-FY93-072. Team A determined the cause of the unacceptable unbonds (referred to as 'heat-affect' unbonds), including the initial, light rust film, in the FSM #3 flex bearing was overheating of the Forward End Ring (FER) during cure, specifically in zone 8 of the mold. Team A's findings are documented in Volume 1 of this report. Team B developed flight rationale for existing bearings, based on absence or presence of an unpropitious unbond condition like that in FSM #3's flex bearing.

  1. Author's personal copy A bi-functional cathode structure for alkaline-acid direct

    E-print Network

    Zhao, Tianshou

    Author's personal copy A bi-functional cathode structure for alkaline-acid direct ethanol fuel 19 August 2011 Keywords: Fuel cell Alkaline-acid direct ethanol fuel cell Bi-functional structure associated with the use of hydrogen peroxide as the oxidant in the so-called alkaline-acid direct ethanol

  2. REDUCTIVE ACTIVATION OF DIOXYGEN FOR DEGRADATION OF METHYL TERT-BUTYL ETHER BY BIFUNCTION

    EPA Science Inventory

    Bifunctional aluminum is prepared by sulfating aluminum metal with sulfuric acid. The use of bifunctional aluminum to degrade methyl tert-butyl ether (MTBE) in the presence of dioxygen has been examined using batch systems. Primary degradation products were tert-butyl alcohol, ...

  3. Motor bearing fluting

    Microsoft Academic Search

    J. A. Lawson

    1993-01-01

    Electrical motor bearing fluting has been defined as damage due to electrical current discharge through a motor bearing. Bearing race metal is electroplated onto the bearing balls. Close inspection reveals microscopic pits on bearing ball and race surfaces. A DC motor frame was completely isolated from ground except by a single grounding conductor with applied armature and field voltage. No

  4. Bifunctional Phage-Based Pretargeted Imaging of Human Prostate Carcinoma Bifunctional Phage Based Pretargeted Imaging

    PubMed Central

    Newton-Northup, Jessica R.; Figueroa, Said D.; Quinn, Thomas P.; Deutscher, Susan L.

    2009-01-01

    Introduction Two-step and three-step pretargeting systems utilizing biotinylated prostate tumor-homing bacteriophage (phage) and 111In-radiolabeled- streptavidin or biotin were developed for use in cancer radioimaging. The in vivo selected prostate carcinoma-specific phage (G1) displaying up to five copies of the peptide IAGLATPGWSHWLAL, was the focus of the present study. Methods The ability of G1 phage to extravasate and target prostate tumor cells was investigated using immunohistochemistry. G1 phage were biotinylated, streptavidin was conjugated to diethylenetriaminepentaacetic acid (DTPA), and biotin was conjugated to 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA). Biodistribution studies and single photon emission computed tomography (SPECT)/CT imaging of xenografted PC-3 tumors via two-step pretargeted 111In-labeled streptavidin and three-step pretargeted 111In-labeled biotin were performed in SCID mice to determine the optimal pretargeting method. Results The ability of G1 phage to extravasate the vasculature and bind directly to human PC-3 prostate carcinoma tumor cells in vivo was demonstrated via immunocytochemical analysis. Comparative biodistribution studies of the two-step and three-step pretargeting strategies indicated increased PC-3 human prostate carcinoma tumor uptake in SCID mice of 4.34 ±0.26 %ID/g at 0.5 hours post-injection of 111In radiolabeled biotin (utilized in a three-step protocol) compared to that of 0.67 ±0.06 %ID/g at twenty four hour postinjection of 111In radiolabeled streptavidin (employed in a two-step protocol). In vivo SPECT/CT imaging of xenografted PC-3 tumors in SCID mice with the three-step pretargeting method was superior to that of the two-step pretargeting method, and, importantly, blocking studies demonstrated specificity of tumor uptake of 111In-labeled biotin in the three-step pretargeting scheme. Conclusion This study demonstrates the use of multivalent bifunctional phage in a three-step pretargeting system for prostate cancer radioimaging. PMID:19720291

  5. Magnetic perturbation inspection of inner bearing races

    NASA Technical Reports Server (NTRS)

    Barton, J. R.; Lankford, J.

    1972-01-01

    Approximately 100 inner race bearings were inspected nondestructively prior to endurance testing. Two of the bearings which failed during testing spalled at the sites of subsurface inclusions previously detected by using magnetic field perturbation. At other sites initially judged to be suspect, subsurface inclusion-nucleated cracking was observed. Inspection records and metallurgical sectioning results are presented and discussed.

  6. Interference Fit Life Factors for Roller Bearings

    NASA Technical Reports Server (NTRS)

    Oswald, Fred B.; Zaretsky, Erwin V.; Poplawski, Joseph V.

    2008-01-01

    The effect of hoop stresses in reducing cylindrical roller bearing fatigue life was determined for various classes of inner ring interference fit. Calculations were performed for up to seven interference fit classes for each of ten bearing sizes. Each fit was taken at tightest, average and loosest values within the fit class for RBEC-5 tolerance, thus requiring 486 separate analyses. The hoop stresses were superimposed on the Hertzian principal stresses created by the applied radial load to calculate roller bearing fatigue life. The method was developed through a series of equations to calculate the life reduction for cylindrical roller bearings based on interference fit. All calculated lives are for zero initial bearing internal clearance. Any reduction in bearing clearance due to interference fit was compensated by increasing the initial (unmounted) clearance. Results are presented as tables and charts of life factors for bearings with light, moderate and heavy loads and interference fits ranging from extremely light to extremely heavy and for bearing accuracy class RBEC 5 (ISO class 5). Interference fits on the inner bearing ring of a cylindrical roller bearing can significantly reduce bearing fatigue life. In general, life factors are smaller (lower life) for bearings running under light load where the unfactored life is highest. The various bearing series within a particular bore size had almost identical interference fit life factors for a particular fit. The tightest fit at the high end of the RBEC-5 tolerance band defined in ANSI/ABMA shaft fit tables produces a life factor of approximately 0.40 for an inner-race maximum Hertz stress of 1200 MPa (175 ksi) and a life factor of 0.60 for an inner-race maximum Hertz stress of 2200 MPa (320 ksi). Interference fits also impact the maximum Hertz stress-life relation.

  7. Divergent evolution of a bifunctional de novo protein.

    PubMed

    Smith, Betsy A; Mularz, Ann E; Hecht, Michael H

    2015-02-01

    Primordial proteins, the evolutionary ancestors of modern sequences, are presumed to have been minimally active and nonspecific. Following eons of selective pressure, these early progenitors evolved into highly active and specific proteins. While evolutionary trajectories from poorly active and multifunctional generalists toward highly active specialists likely occurred many times in evolutionary history, such pathways are difficult to reconstruct in natural systems, where primordial sequences are lost to time. To test the hypothesis that selection for enhanced activity leads to a loss of promiscuity, we evolved a de novo designed bifunctional protein. The parental protein, denoted Syn-IF, was chosen from a library of binary patterned 4-helix bundles. Syn-IF was shown previously to rescue two different auxotrophic strains of E. coli: ?ilvA and ?fes. These two strains contain deletions for proteins with very different biochemical functions; IlvA is involved in isoleucine biosynthesis, while Fes is involved in iron assimilation. In two separate experiments, Syn-IF, was evolved for faster rescue of either ?ilvA or ?fes. Following multiple rounds of mutagenesis, two new proteins were selected, each capable of rescuing the selected function significantly faster than the parental protein. In each case, the evolved protein also lost the ability to rescue the unselected function. In both evolutionary trajectories, the original bifunctional generalist was evolved into a monofunctional specialist with enhanced activity. PMID:25420677

  8. Photovoltachromic device with a micropatterned bifunctional counter electrode.

    PubMed

    Cannavale, Alessandro; Manca, Michele; De Marco, Luisa; Grisorio, Roberto; Carallo, Sonia; Suranna, Gian Paolo; Gigli, Giuseppe

    2014-02-26

    A photovoltachromic window can potentially act as a smart glass skin which generates electric energy as a common dye-sensitized solar cell and, at the same time, control the incoming energy flux by reacting to even small modifications in the solar radiation intensity. We report here the successful implementation of a novel architecture of a photovoltachromic cell based on an engineered bifunctional counter electrode consisting of two physically separated platinum and tungsten oxide regions, which are arranged to form complementary comb-like patterns. Solar light is partially harvested by a dye-sensitized photoelectrode made on the front glass of the cell which fully overlaps a bifunctional counter electrode made on the back glass. When the cell is illuminated, the photovoltage drives electrons into the electrochromic stripes through the photoelectrochromic circuit and promotes the Li(+) diffusion towards the WO3 film, which thus turns into its colored state: a photocoloration efficiency of 17 cm(2) min(-1) W(-1) at a wavelength of 650 nm under 1.0 sun was reported along with fast response (coloration time <2 s and bleaching time <5 s). A fairly efficient photovoltaic functionality was also retained due to the copresence of the independently switchable micropatterned platinum electrode. PMID:24460118

  9. Initial comparison of Cu-67-and Cu-64-labeled anti-colorectal carcinoma Mab 1A3 as agents for radioimmunotherapy in tumor-bearing hamsters

    SciTech Connect

    Anderson, C.J.; Connett, J.M.; Guo, L.W. [Washington Univ. School of Medicine, St. Louis, MO (United States)] [and others

    1994-05-01

    For imaging or radiotherapy, {sup 64}Cu (T{sub 1/2}=12.8 h) has advantages over {sup 67}Cu (T{sub 1/2}=62h) that include wider availibility, lower cost, and a higher specific activity. {sup 67}Cu- and {sup 64}Cu- labeled monoclonal antibody (MAb) 1A3 showed similar lethal efficiencies in vitro to LS174T human colon cancer cells. To compare the lethal effiencies of these agents in vivo, 200 or 400 {mu}Ci of {sup 67}Cu-labeled Mab 1A3 and 500, 1000 or 2000 {mu}Ci of {sup 64}Cu-labeled 1A3 were administered into hamsters carrying 2 day old GW-39 human colon tumors in their thigh musculature. In another group of hamsters, {sup 67}Cu- and {sup 64}Cu-labeled non-specific Mab MOPC were also administered in corresponding amounts. A control group was injected with saline solution. At all doses, hamsters that were given either {sup 64}Cu- or {sup 67}Cu-labeled 1A3 showed inhibition of tumor growth over hamsters injected with either saline or {sup 64}Cu- or {sup 67}Cu-labeled MOPC. Tumor weights in hamsters administered with 2000 {mu}Ci of {sup 64}Cu-1A3 showed an 11-fold decrease over tumors in hamsters given saline (0.184 {plus_minus} 0.106 (n=3) vs 2.056 {plus_minus} 0.369 (n=10)), and a 5-fold decrease over those where {sup 64}Cu-MOPC was administered (0.184 {plus_minus} 0.106 (n=3) vs 0.961 {plus_minus} 0.228 (n=4)). In hamsters injected with 400 {mu}Ci {sup 67}Cu-1A3, a 13-fold decrease in tumor weight was observed over control hamsters given saline (0.345 {plus_minus} 0.129 (n=5)vs 4.457 {plus_minus}0.405 (n=10)), and a 7-fold decrease was observed when {sup 67}Cu-MOPC was injected (0.345 {plus_minus} 0.129 (n=5) vs 2.507 {plus_minus} 1.064 (n=5)). Given the 5-fold difference in half-life between {sup 67}Cu and {sup 64}Cu, at corresponding doses the inhibition of tumor growth was similar. These initial experiments indicate that {sup 64}Cu has a radiotherapeutic potential comparable to {sup 67}Cu when labeled to Mab 1A3.

  10. Preparation of Pt/Irx(IrO2)10 - x bifunctional oxygen catalyst for unitized regenerative fuel cell

    NASA Astrophysics Data System (ADS)

    Kong, Fan-Dong; Zhang, Sheng; Yin, Ge-Ping; Zhang, Na; Wang, Zhen-Bo; Du, Chun-Yu

    2012-07-01

    Bifunctional Pt/Irx(IrO2)10 - x (x < 10) catalyst for unitized regenerative fuel cell (URFC) has been prepared by depositing Pt on Irx(IrO2)10 - x support which is obtained initially from Adams fusion method. X-ray diffraction and transmission electron microscopy show that ultrafine and narrow distributed Pt/Ir3(IrO2)7 nanocomposites are formed. Electrochemical measurements demonstrate that among the series of catalysts studied, Pt/Ir3(IrO2)7 catalyst possesses the highest electrochemical surface area (24.74 m2 g-1) and the highest activity towards oxygen reduction reaction (ORR) (21.71 mA mg-1 at 0.85 V). Meanwhile, considerably high activity towards oxygen evolution reaction (OER) (42.35 mA mg-1 at 1.55 V) is also observed for Pt/Ir3(IrO2)7 catalyst. Kinetic analyses indicate that ORR on Pt/Ir3(IrO2)7 catalyst follows four-electron mechanism. This work opens a new way to fabricate efficient bifunctional oxygen catalyst for URFC.

  11. Sulfur electrode modified by bifunctional nafion/?-Al2O3 membrane for high performance lithium-sulfur batteries

    NASA Astrophysics Data System (ADS)

    Liu, Xiaoyan; Shan, Zhongqiang; Zhu, Kunlei; Du, Jiangyong; Tang, Qiwei; Tian, Jianhua

    2015-01-01

    Lithium sulfur batteries have brought significant advancement to the current state-of-art battery technologies due to their high theoretical specific energy of 1675 mAh g-1. However, the rapid capacity degradation, mainly caused by polysulfide dissolution, remains a significant challenge prior to practical applications. In this work, a sulfur cathode modified by bifunctional nafion/?-Al2O3 membrane has been successfully prepared, which can remarkably immobilize the polysulfides within the unique cathode structure due to its ions selectivity and absorbent capacity. A high initial discharge capacity of 1448.0 mAh g-1 can be achieved at 1C and 788.6 mAh g-1 preserved after 200 cycles, indicating a slow degradation. Furthermore, the coulombic efficiency maintains as high as 97% during cycling. The excellent electrochemical properties can be attributed to the bifunctional and stable membrane which can dramatically reduce the shuttle effect and keep integrated even after charging-discharging for 200 cycles.

  12. AURALISATION OF ROLLING BEARINGS

    Microsoft Academic Search

    Michael Vorländer; João Henrique; Diniz Guimarães

    Monitoring the operating conditions of rolling bearings and prediction of the remaining lifetime of bearings is one of the most crucial tasks in machine diagnosis. This work presents the results of the auralization of structure-borne sound in bearings and the transmission in machines. These signals correspond to the vibration measured on the machine's housing generated by cylindrical and ball bearings

  13. Rolling-Element Bearings

    NASA Technical Reports Server (NTRS)

    Hamrock, B. J.; Anderson, W. J.

    1983-01-01

    Rolling element bearings are a precision, yet simple, machine element of great utility. A brief history of rolling element bearings is reviewed and the type of rolling element bearings, their geometry and kinematics, as well as the materials they are made from and the manufacturing processes they involve are described. Unloaded and unlubricated rolling element bearings, loaded but unlubricated rolling element bearings and loaded and lubricated rolling element bearings are considered. The recognition and understanding of elastohydrodynamic lubrication covered, represents one of the major development in rolling element bearings.

  14. Introduction to ball bearings

    NASA Technical Reports Server (NTRS)

    Hamrock, B. J.; Dowson, D.

    1981-01-01

    The purpose of a ball bearing is to provide a relative positioning and rotational freedom while transmitting a load between two structures, usually a shaft and a housing. For high rotational speeds (e.g., in gyroscope ball bearings) the purpose can be expanded to include rotational freedom with practically no wear in the bearing. This condition can be achieved by separating the bearing parts with a coherent film of fluid known as an elastohydrodynamic film. This film can be maintained not only when the bearing carries the load on a shaft, but also when the bearing is preloaded to position the shaft to within micro- or nano-inch accuracy and stability. Background information on ball bearings is provided, different types of ball bearings and their geometry and kinematics are defined, bearing materials, manufacturing processes, and separators are discussed. It is assumed, for the purposes of analysis, that the bearing carries no load.

  15. High efficiency magnetic bearings

    NASA Technical Reports Server (NTRS)

    Studer, Philip A.; Jayaraman, Chaitanya P.; Anand, Davinder K.; Kirk, James A.

    1993-01-01

    Research activities concerning high efficiency permanent magnet plus electromagnet (PM/EM) pancake magnetic bearings at the University of Maryland are reported. A description of the construction and working of the magnetic bearing is provided. Next, parameters needed to describe the bearing are explained. Then, methods developed for the design and testing of magnetic bearings are summarized. Finally, a new magnetic bearing which allows active torque control in the off axes directions is discussed.

  16. Feature Evaluation for Effective Bearing Prognostics , K. Medjaherb

    E-print Network

    Paris-Sud XI, Université de

    that has shorter remaining useful life than the defected one. Thus, prognostics of bearing plays critical are typically designed to have a life greater than the subsystem they are in. Failure initiation in bearings, it is not uncommon to replace a defected/used bearing with a new one that has shorter remaining useful life than

  17. Hypoxia targeted bifunctional suicide gene expression enhances radiotherapy in vitro and in vivo

    PubMed Central

    Sun, Xiaorong; Xing, Ligang; Deng, Xuelong; Hsiao, Hung Tsung; Manami, Akiko; Koutcher, Jason A.; Ling, C. Clifton; Li, Gloria C.

    2013-01-01

    Purpose To investigate whether hypoxia targeted bifunctional suicide gene expression-cytosine deaminase (CD) and uracil phosphoribosyltransferase (UPRT) with 5-FC treatments can enhance radiotherapy. Material and Methods Stable transfectant of R3327-AT cells were established which express a triple-fusion-gene: CD, UPRT and monomoric DsRed (mDsRed) controlled by a hypoxia inducible promoter. Hypoxia-induced expression/function of CDUPRTmDsRed was varified by western blot, flow cytometry, fluorescent microscopy, and cytotoxicity assay of 5-FU and 5-FC. Tumor-bearing mice were treated with 5-FC and locally radiation. Tumor volume were monitored and compared with those treated with 5-FC or radiation alone. In addition, the CDUPRTmDsRed distribution in hypoxic regions of tumor sections was visualized with fluorescent microscopy. Results Hypoxic induction of CDUPRTmDsRed protein correlated with increased sensitivity to 5-FC and 5-FU. Significant radiosensitization effects were detected after 5-FC treatments under hypoxic conditions. In the tumor xenografts, the distribution of CDUPRTmDsRed expression visualized with fluorescence microscopy was co-localized with the hypoxia marker pimonidazole positive staining cells. Furthermore, administration of 5-FC to mice in combined with local irradiation resulted in significant tumor regression, as comparison with 5-FC or radiation treatments alone. Conclusions Our data suggest that the hypoxia-inducible CDUPRT/5-FC gene therapy strategy has the ability to specifically target hypoxic cancer cells and significantly improves the tumor control in combination with radiotherapy. PMID:22938726

  18. Structures and Modes of Reactions of Some Hexachlorocyclodiphosphazane With Some Bifunctional Reagents

    Microsoft Academic Search

    E. H. M. Ibrahim

    1989-01-01

    Aminocyclodiphosph(v)azanes of the type (II-V) obtained from the interaction of hexachlorocyclodiphosphazanes (I) with some bifunctional reagents (such as phenylurea, diphenylurea, thiourea and its phenyl derivatives) in acetonitrile, have been discussed.

  19. Bifunctional magnetic-fluorescent nanoparticles: synthesis, characterization, and cell imaging.

    PubMed

    Lu, Yanjiao; Zheng, Yang; You, Shusen; Wang, Feng; Gao, Zhuo; Shen, Jie; Yang, Wantai; Yin, Meizhen

    2015-03-11

    A new type of bifunctional magnetic-fluorescent Fe3O4@SiO2-PDI-PAA/Ca(2+) nanoparticles has been prepared by coating PDI-cored star polymers (PDI-PAA) onto the surface of Fe3O4@SiO2 core-shell nanostructures. The morphology and properties of the composite nanoparticles are investigated by transmission electron microscopy, ultraviolet-visible spectrometry, fluorescence spectrometry, and vibrating sample magnetometry. The composite nanoparticles display a strong red emission and superparamagnetic behavior at room temperature. The cell viability and uptake assays reveal good biocompatibility of these hybrid nanoparticles. Hence, the composite nanoparticles are of potential to be further explored as therapeutic vector in biomedical field. PMID:25691125

  20. Experimental Realization of Simultaneous and Independent Manipulation of Thermal and Electric Fields with Bifunctional Metamaterials

    E-print Network

    Lan, Chuwen; Zhou, Ji

    2015-01-01

    Here, we report the experimental realization of simultaneous and independent manipulation of thermal and electric fields with bifunctional metamaterials. A composite with independently controllable thermal and electric conductivity was introduced and exploited to achieve independent manipulation of thermal and electric fields. A bifunctional device capable of shielding thermal flux and concentrating electric current simultaneously was designed, fabricated and characterized. This work provides a novel way towards independently tailoring material properties, which would pave a broad platform for manipulation of multi-physics field.

  1. Metal@Silica yolk-shell nanostructures as versatile bifunctional nanocatalysts

    Microsoft Academic Search

    Ji Chan Park; Hyunjoon Song

    2011-01-01

    Recent developments in nanochemistry offer precise morphology control of nanomaterials, which has significant impacts in the\\u000a field of heterogeneous catalysis. Rational design of bifunctional catalysts can influence various aspects of catalytic properties.\\u000a In this review, a new class of bifunctional catalysts with a metal@silica yolk-shell nanostructure is introduced. This structure\\u000a has many advantages as a heterogeneous catalyst since it ensures

  2. Imaging Cancer Using PET – the Effect of the Bifunctional Chelator on the Biodistribution of a 64Cu-Labeled Antibody

    PubMed Central

    Dearling, Jason L.J.; Voss, Stephan D.; Dunning, Patricia; Snay, Erin; Fahey, Frederic; Smith, Suzanne V.; Huston, James S.; Meares, Claude F.; Treves, S. Ted; Packard, Alan B.

    2010-01-01

    Introduction Use of copper radioisotopes in antibody radiolabeling is challenged by reported loss of the radionuclide from the bifunctional chelator used to label the protein. The objective of this study was to investigate the relationship between the thermodynamic stability of the 64Cu-complexes of five commonly used bifunctional chelators (BFCs) and the biodistribution of an antibody labeled with 64Cu using these chelators in tumor-bearing mice. Methods The chelators (p-NH2-Bn-NOTA, BAT-6, p-NH2-Bn-DOTA, DOTA, and SarAr) were conjugated to the anti-GD2 antibody ch14.18, and the conjugated antibody was labeled with 64Cu and injected into mice bearing subcutaneous human melanoma tumors (M21) (n = 3-5 for each study). Biodistribution data were obtained from PET images acquired at 1, 24 and 48 hours post-injection, and at 48 hours post-injection a full ex vivo biodistribution study was carried out. Results The biodistribution, including tumor targeting, was similar for all the radioimmunoconjugates. At 48 h post-injection, the only statistically significant differences in radionuclide uptake (p < 0.05) were between blood, liver, spleen and kidney. For example, liver uptake of [64Cu]ch14.18-p-NH2-Bn-NOTA was 4.74 ± 0.77 per cent of the injected dose per gram of tissue (%ID/g), and for [64Cu]ch14.18-SarAr was 8.06 ± 0.77 %ID/g. Differences in tumor targeting correlated with variations in tumor size rather than which BFC was used. Conclusions The results of this study indicate that differences in the thermodynamic stability of these chelator-Cu(II) complexes were not associated with significant differences in uptake of the tracer by the tumor. However, there were significant differences in tracer concentration in other tissues, including those involved in clearance of the radioimmunoconjugate (e.g., liver and spleen). PMID:21220127

  3. Bifunctional Binding of Cisplatin to DNA: Why Does Cisplatin Form 1,2-Intrastrand Cross-links with AG, But Not with GA?

    PubMed Central

    Mantri, Yogita; Lippard, Stephen J.; Baik, Mu-Hyun

    2008-01-01

    The bifunctional binding of the anticancer drug cisplatin to two adjacent nucleobases in DNA is modeled using density functional theory. Previous experimental studies revealed that cisplatin binding to adjacent guanine and adenine is sensitive to nucleobase sequence. Whereas AG 1,2-intrastrand cross-links are commonly observed, the analogous GA adducts are not known. This study focuses on understanding this directional preference by constructing a full reaction profile using quantum chemical simulation methods. Monofunctional and bifunctional cisplatin adducts were generated and the transition states that connect them were located for the dinucleotides d(pApG) and d(pGpA), assuming that initial platination takes place at the guanine site. Our computer simulations reveal a significant kinetic preference for formation of the AG over the GA adduct. The activation free energies of ~23 kcal/mol for AG and ~32 kcal/mol for GA suggest that bifunctional closure is ~6 orders of magnitude faster for AG than for GA. Responsible for the stabilization of the transition state that affords the AG adduct is a strong hydrogen bond between one of the ammine ligands of cisplatin and the 5? phosphate group of the DNA backbone. This interaction is absent in the transition state that leads to the GA adduct, because the right-handed helix of the DNA backbone places the phosphate out of reach for the ammine ligand. We found only an insignificant thermodynamic difference between AG and GA adducts and conclude that the preference of AG over GA binding is largely under kinetic control. The puckering of the deoxyribose ring plays an important role in determining the energetics of the bifunctional platination products. Whereas the 3?-nucleoside remains in the native C2?-endo/C3?-exo form of B-DNA, the deoxyribose of the 5?-nucleoside always adopts the C2?-exo/C3?-endo puckering in our simulations. A detailed analysis of the energies and structures of the bifunctional adducts revealed that the observed sugar puckering patterns are necessary for platinum to bind in a relaxed coordination geometry. PMID:17402732

  4. Tracking Polar Bears

    NSDL National Science Digital Library

    WGBH Educational Foundation

    2008-01-17

    In this interactive activity adapted from the USGS Alaska Science Center, track the movements of a polar bear as it migrates across the changing Arctic sea ice and compare the paths of four different polar bears.

  5. Catalytic, Enantioselective Bifunctional Inverse Electron Demand Hetero-Diels-Alder Reactions of Ketene Enolates and o-Benzoquinone

    E-print Network

    Lectka, Thomas

    Catalytic, Enantioselective Bifunctional Inverse Electron Demand Hetero-Diels-Alder Reactions@jhu.edu Catalytic, enantioselective Diels-Alder reactions ([4 + 2] cycloadditions) constitute a vital part

  6. Axial Halbach Magnetic Bearings

    NASA Technical Reports Server (NTRS)

    Eichenberg, Dennis J.; Gallo, Christopher A.; Thompson, William K.

    2008-01-01

    Axial Halbach magnetic bearings have been investigated as part of an effort to develop increasingly reliable noncontact bearings for future high-speed rotary machines that may be used in such applications as aircraft, industrial, and land-vehicle power systems and in some medical and scientific instrumentation systems. Axial Halbach magnetic bearings are passive in the sense that unlike most other magnetic bearings that have been developed in recent years, they effect stable magnetic levitation without need for complex active control.

  7. Status of understanding for bearing materials

    SciTech Connect

    Bamberger, E.N.

    1984-04-01

    The structural materials and potential failure modes for high technology aircraft gas turbine bearings are reviewed. Among the failure modes discussed for iron-base through-hardened bearing materials are fatigue, surface distress, and corrosion. It is shown that the sub-surface initiated rolling-contact fatigue failure mode is reasonably well understood and in most cases can be controlled by proper material selection and design. Current bearing materials provide long life and high reliability in existing applications. A new generation of materials are being developed which will provide improved fracture toughness, better corrosion resistance, and a further extension of bearing fatigue life. Bearing problems due to surface distress, caused by a variety of surface and near surface anomalies, are less well understood. This area will require the implementation of an interdisciplinary effort to improve the level of understanding of metallic surface-lubricant reactions and interactions.

  8. Cryogenic Hybrid Magnetic Bearing

    NASA Technical Reports Server (NTRS)

    Meeks, Crawford R.; Dirusso, Eliseo; Brown, Gerald V.

    1994-01-01

    Cryogenic hybrid magnetic bearing is example of class of magnetic bearings in which permanent magnets and electromagnets used to suspend shafts. Electromagnets provide active control of position of shaft. Bearing operates at temperatures from -320 degrees F (-196 degrees C) to 650 degrees F (343 degrees C); designed for possible use in rocket-engine turbopumps, where effects of cryogenic environment and fluid severely limit lubrication of conventional ball bearings. This and similar bearings also suitable for terrestrial rotating machinery; for example, gas-turbine engines, high-vacuum pumps, canned pumps, precise gimbals that suspend sensors, and pumps that handle corrosive or gritty fluids.

  9. Status of understanding for bearing materials

    Microsoft Academic Search

    Bamberger

    1984-01-01

    The structural materials and potential failure modes for high technology aircraft gas turbine bearings are reviewed. Among the failure modes discussed for iron-base through-hardened bearing materials are fatigue, surface distress, and corrosion. It is shown that the sub-surface initiated rolling-contact fatigue failure mode is reasonably well understood and in most cases can be controlled by proper material selection and design.

  10. Zirconium-labeled monoclonal antibodies and their distribution in tumor-bearing nude mice

    SciTech Connect

    Meijs, W.E.; Haisma, H.J.; Klok, R.P. [Vrije Univ. Hospital, Amsterdam (Netherlands)] [and others

    1997-01-01

    A method to label monoclonal antibodies (MAbs) with {sup 88}Zr and {sup 89}Zr has been developed and tested on the MAbs 323/A3 and E48. The bifunctional chelating agent desferal (Df) was linked through a thioether bond to the MAbs. Labeling was accomplished by addition of the premodified antibodies to isolated Zr. The retention of the in vivo behavior of the MAbs was determined by comparing the biodistribution of {sup 88}Zr-labeled MAbs with those of {sup 123}I and {sup 99m}Tc in mice bearing tumor xenografts. 45 refs., 7 figs., 1 tab.

  11. Single flexible nanofiber to achieve simultaneous photoluminescence-electrical conductivity bifunctionality.

    PubMed

    Sheng, Shujuan; Ma, Qianli; Dong, Xiangting; Lv, Nan; Wang, Jinxian; Yu, Wensheng; Liu, Guixia

    2015-02-01

    In order to develop new-type multifunctional composite nanofibers, Eu(BA)3 phen/PANI/PVP bifunctional composite nanofibers with simultaneous photoluminescence and electrical conductivity have been successfully fabricated via electrospinning technology. Polyvinyl pyrrolidone (PVP) is used as a matrix to construct composite nanofibers containing different amounts of Eu(BA)3 phen and polyaniline (PANI). X-Ray diffractometry (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), vibrating sample magnetometry (VSM), fluorescence spectroscopy and a Hall effect measurement system are used to characterize the morphology and properties of the composite nanofibers. The results indicate that the bifunctional composite nanofibers simultaneously possess excellent photoluminescence and electrical conductivity. Fluorescence emission peaks of Eu(3+) ions are observed in the Eu(BA)3 phen/PANI/PVP photoluminescence-electrical conductivity bifunctional composite nanofibers. The electrical conductivity reaches up to the order of 10(-3) ?S/cm. The luminescent intensity and electrical conductivity of the composite nanofibers can be tuned by adjusting the amounts of Eu(BA)3 phen and PANI. The obtained photoluminescence-electrical conductivity bifunctional composite nanofibers are expected to possess many potential applications in areas such as microwave absorption, molecular electronics, biomedicine and future nanomechanics. More importantly, the design concept and construction technique are of universal significance to fabricate other bifunctional one-dimensional naonomaterials. PMID:24817327

  12. Design principles for bifunctional targeted oligonucleotide enhancers of splicing

    PubMed Central

    Owen, Nicholas; Zhou, Haiyan; Malygin, Alexey A.; Sangha, Jason; Smith, Lindsay D.; Muntoni, Francesco; Eperon, Ian C.

    2011-01-01

    Controlling the patterns of splicing of specific genes is an important goal in the development of new therapies. We have shown that the splicing of a refractory exon, SMN2 exon 7, could be increased in fibroblasts derived from patients with spinal muscular atrophy by using bifunctional targeted oligonucleotide enhancers of splicing (TOES) oligonucleotides that anneal to the exon and contain a ‘tail’ of enhancer sequences that recruit activating proteins. We show here that there are striking agreements between the effects of oligonucleotides on splicing in vitro and on both splicing and SMN2 protein expression in patient-derived fibroblasts, indicating that the effects on splicing are the major determinant of success. Increased exon inclusion depends on the number, sequence and chemistry of the motifs that bind the activator protein SRSF1, but it is not improved by increasing the strength of annealing to the target site. The optimal oligonucleotide increases protein levels in transfected fibroblasts by a mean value of 2.6-fold (maximum 4.6-fold), and after two rounds of transfection the effect lasted for a month. Oligonucleotides targeted to the upstream exon (exon 6 in SMN) are also effective. We conclude that TOES oligonucleotides are highly effective reagents for restoring the splicing of refractory exons and can act across long introns. PMID:21602265

  13. Magnetic-plasmonic bifunctional CoO-Ag heterostructure nanoparticles

    NASA Astrophysics Data System (ADS)

    Yang, Jianhui; Cao, Beibei; Liu, Bin

    2014-03-01

    We demonstrate the synthesis of CoO-Ag heterostructure nanoparticles by chemical reduction of AgNO3 in the presence of Co nanoparticles in oleylamine (OAm). OAm plays multiple roles as a surfactant, solvent, and reducing agent. The mechanism of surface-activated heterogeneous nucleation and growth on the preformed seeds has been proposed. At the same time, the Co nanoparticles are oxidized to form hollow CoO nanoparticles through the Kirkendall effect. The resulting CoO-Ag heterostructures display mushroom-like morphology, Ag nanoparticle as ‘cap’ attached on the ‘stem’ of hollow CoO nanoparticles. The size of Ag domains in the heterostructure nanoparticles can be tuned by controlling the volume of Co nanoparticles. The plasmonic absorption and the magnetization of the bifunctional nanoparticles were investigated. The combination of the hollow structure of the CoO and the surface plasmon resonances of the Ag domains may make them suitable for catalysis, drug delivery, therapy, and surface-enhanced Raman scattering.

  14. Gold-Copper Nanoparticles: Nanostructural Evolution and Bifunctional Catalytic Sites

    SciTech Connect

    Yin, Jun; Shan, Shiyao; Yang, Lefu; Mott, Derrick; Malis, Oana; Petkov, Valeri; Cai, Fan; Ng, Mei; Luo, Jin; Chen, Bing H.; Engelhard, Mark H.; Zhong, Chuan-Jian

    2012-12-12

    Understanding of the atomic-scale structure is essential for exploiting the unique catalytic properties of any nanoalloy catalyst. This report describes novel findings of an investigation of the nanoscale alloying of gold-copper (AuCu) nanoparticles and its impact on the surface catalytic functions. Two pathways have been explored for the formation of AuCu nanoparticles of different compositons, including wet chemical synthesis from mixed Au- and Cu-precursor molecules, and nanoscale alloying via an evolution of mixed Au- and Cu-precursor nanoparticles near the nanoscale melting temperatures. For the evolution of mixed precursor nanoparticles, synchrotron x-ray based in-situ real time XRD was used to monitor the structural changes, revealing nanoscale alloying and reshaping towards an fcc-type nanoalloy (particle or cube) via a partial melting–resolidification mechanism. The nanoalloys supported on carbon or silica were characterized by in-situ high-energy XRD/PDFs, revealing an intriguing lattice "expanding-shrinking" phenomenon depending on whether the catalyst is thermochemically processed under oxidative or reductive atmosphere. This type of controllable structural changes is found to play an important role in determining the catalytic activity of the catalysts for carbon monoxide oxidation reaction. The tunable catalytic activities of the nanoalloys under thermochemically oxidative and reductive atmospheres are also discussed in terms of the bifunctional sites and the surface oxygenated metal species for carbon monoxide and oxygen activation.

  15. The Incredible Water Bear

    NSDL National Science Digital Library

    Martin Mach

    This image-rich Micscape Magazine article explores how water bears can be found almost everywhere yet are still unknown to almost everybody, why there are relatively few light microscope photographs of water bears in the literature and on the Web, and how light microscopy can outperform scanning electron microscopy when viewing these animals. It includes a list of historical references, early sketches, and colorful images of water bears, also known as tardigrades.

  16. New Volunteer Guidebook For volunteers teaching credit-bearing courses at Mt.

    E-print Network

    New Volunteer Guidebook For volunteers teaching credit-bearing courses at Mt. McGregor Correctional Initiative provides free, credit-bearing Siena College courses to the men of Mt. McGregor CorrectionalGregor College Initiative provides free, credit-bearing Siena College courses to the men of Mt. Mc

  17. Polymer-Supported Reagents: The Role of Bifunctionality in the Design of Ion-Selective Complexants

    SciTech Connect

    Alexandratos, S. D.

    2001-06-01

    The importance of multi-functionality in the preparation of ion-selective polymers is evident from the structure of enzymes where specific metal ions are bound through cooperative interactions among different amino acids. In synthetic polymers, ionic selectivity is enhanced when a chemical reaction is superimposed on an ion-exchange process. The concept of reactive ion exchange has been extended through the synthesis of crosslinked polymers whose metal ion selectivity is a function of reduction, coordination or precipitation reactions as determined by various covalently bound ligands. Development of three classes of dual mechanism bifunctional polymers, a new series of bifunctional diphosphonate polymers, and novel bifunctional ion-selective polymers with enhanced ionic accessibility has been accomplished.

  18. Evolution of conifer diterpene synthases: diterpene resin acid biosynthesis in lodgepole pine and jack pine involves monofunctional and bifunctional diterpene synthases.

    PubMed

    Hall, Dawn E; Zerbe, Philipp; Jancsik, Sharon; Quesada, Alfonso Lara; Dullat, Harpreet; Madilao, Lina L; Yuen, Macaire; Bohlmann, Jörg

    2013-02-01

    Diterpene resin acids (DRAs) are major components of pine (Pinus spp.) oleoresin. They play critical roles in conifer defense against insects and pathogens and as a renewable resource for industrial bioproducts. The core structures of DRAs are formed in secondary (i.e. specialized) metabolism via cycloisomerization of geranylgeranyl diphosphate (GGPP) by diterpene synthases (diTPSs). Previously described gymnosperm diTPSs of DRA biosynthesis are bifunctional enzymes that catalyze the initial bicyclization of GGPP followed by rearrangement of a (+)-copalyl diphosphate intermediate at two discrete class II and class I active sites. In contrast, similar diterpenes of gibberellin primary (i.e. general) metabolism are produced by the consecutive activity of two monofunctional class II and class I diTPSs. Using high-throughput transcriptome sequencing, we discovered 11 diTPS from jack pine (Pinus banksiana) and lodgepole pine (Pinus contorta). Three of these were orthologous to known conifer bifunctional levopimaradiene/abietadiene synthases. Surprisingly, two sets of orthologous PbdiTPSs and PcdiTPSs were monofunctional class I enzymes that lacked functional class II active sites and converted (+)-copalyl diphosphate, but not GGPP, into isopimaradiene and pimaradiene as major products. Diterpene profiles and transcriptome sequences of lodgepole pine and jack pine are consistent with roles for these diTPSs in DRA biosynthesis. The monofunctional class I diTPSs of DRA biosynthesis form a new clade within the gymnosperm-specific TPS-d3 subfamily that evolved from bifunctional diTPS rather than monofunctional enzymes (TPS-c and TPS-e) of gibberellin metabolism. Homology modeling suggested alterations in the class I active site that may have contributed to their functional specialization relative to other conifer diTPSs. PMID:23370714

  19. Synthesis, characterization and catalytic activity of acid-base bifunctional materials through protection of amino groups

    SciTech Connect

    Shao, Yanqiu [College of Chemistry, Jilin University, Changchun 130023 (China) [College of Chemistry, Jilin University, Changchun 130023 (China); College of Chemistry, Mudanjiang Normal University, Mudanjiang 157012 (China); Liu, Heng; Yu, Xiaofang [College of Chemistry, Jilin University, Changchun 130023 (China)] [College of Chemistry, Jilin University, Changchun 130023 (China); Guan, Jingqi, E-mail: guanjq@jlu.edu.cn [College of Chemistry, Jilin University, Changchun 130023 (China)] [College of Chemistry, Jilin University, Changchun 130023 (China); Kan, Qiubin, E-mail: qkan@mail.jlu.edu.cn [College of Chemistry, Jilin University, Changchun 130023 (China)] [College of Chemistry, Jilin University, Changchun 130023 (China)

    2012-03-15

    Graphical abstract: Acid-base bifunctional mesoporous material SO{sub 3}H-SBA-15-NH{sub 2} was successfully synthesized under low acidic medium through protection of amino groups. Highlights: Black-Right-Pointing-Pointer The acid-base bifunctional material SO{sub 3}H-SBA-15-NH{sub 2} was successfully synthesized through protection of amino groups. Black-Right-Pointing-Pointer The obtained bifunctional material was tested for aldol condensation. Black-Right-Pointing-Pointer The SO{sub 3}H-SBA-15-NH{sub 2} catalyst containing amine and sulfonic acid groups exhibited excellent acid-basic properties. -- Abstract: Acid-base bifunctional mesoporous material SO{sub 3}H-SBA-15-NH{sub 2} was successfully synthesized under low acidic medium through protection of amino groups. X-ray diffraction (XRD), N{sub 2} adsorption-desorption, transmission electron micrographs (TEM), back titration, {sup 13}C magic-angle spinning (MAS) NMR and {sup 29}Si magic-angle spinning (MAS) NMR were employed to characterize the synthesized materials. The obtained bifunctional material was tested for aldol condensation reaction between acetone and 4-nitrobenzaldehyde. Compared with monofunctional catalysts of SO{sub 3}H-SBA-15 and SBA-15-NH{sub 2}, the bifunctional sample of SO{sub 3}H-SBA-15-NH{sub 2} containing amine and sulfonic acid groups exhibited excellent acid-basic properties, which make it possess high activity for the aldol condensation.

  20. Past Performance analysis of HPOTP bearings

    NASA Technical Reports Server (NTRS)

    Bhat, B. N.; Dolan, F. J.

    1982-01-01

    The past performance analysis conducted on three High Pressure Oxygen Turbopump (HPOTP) bearings from the Space Shuttle Main Engine is presented. Metallurgical analysis of failed bearing balls and races, and wear track and crack configuration analyses were carried out. In addition, one bearing was tested in laboratory at very high axial loads. The results showed that the cracks were surface initiated and propagated into subsurface locations at relatively small angles. Subsurface cracks were much more extensive than was appeared on the surface. The location of major cracks in the races corresponded to high radial loads rather than high axial loads. There was evidence to suggest that the inner races were heated to elevated temperatures. A failure scenario was developed based on the above findings. According to this scenario the HPOTP bearings are heated by a combination of high loads and high coefficient of friction (poor lubrication). Different methods of extending the HPOTP bearing life are also discussed. These include reduction of axial loads, improvements in bearing design, lubrication and cooling, and use of improved bearing materials.

  1. Janus nanobelts: fabrication, structure and enhanced magnetic-fluorescent bifunctional performance

    NASA Astrophysics Data System (ADS)

    Ma, Qianli; Yu, Wensheng; Dong, Xiangting; Wang, Jinxian; Liu, Guixia

    2014-02-01

    A new nanostructure of magnetic-fluorescent bifunctional Janus nanobelts with Fe3O4/PMMA as one half and Tb(BA)3phen/PMMA as the other half has been successfully fabricated by a specially designed parallel spinneret electrospinning technology. The morphology and properties of the final products were investigated in detail by X-ray diffractometry (XRD), scanning electron microscopy (SEM), energy dispersive spectrometry (EDS), biological microscopy (BM), vibrating sample magnetometry (VSM) and fluorescence spectroscopy. The results revealed that the [Fe3O4/PMMA]//[Tb(BA)3phen/PMMA] magnetic-fluorescent bifunctional Janus nanobelts possess superior magnetic and fluorescent properties due to their special nanostructure. Compared with Fe3O4/Tb(BA)3phen/PMMA composite nanobelts, the magnetic-fluorescent bifunctional Janus nanobelts provided better performance. The new magnetic-fluorescent bifunctional Janus nanobelts have potential applications in novel nano-bio-label materials, drug target delivery materials and future nanodevices due to their excellent magnetic-fluorescent properties, flexibility and insolubility. Moreover, the construction technique for the Janus nanobelts is of universal significance for the fabrication of other multifunctional Janus nanobelts.A new nanostructure of magnetic-fluorescent bifunctional Janus nanobelts with Fe3O4/PMMA as one half and Tb(BA)3phen/PMMA as the other half has been successfully fabricated by a specially designed parallel spinneret electrospinning technology. The morphology and properties of the final products were investigated in detail by X-ray diffractometry (XRD), scanning electron microscopy (SEM), energy dispersive spectrometry (EDS), biological microscopy (BM), vibrating sample magnetometry (VSM) and fluorescence spectroscopy. The results revealed that the [Fe3O4/PMMA]//[Tb(BA)3phen/PMMA] magnetic-fluorescent bifunctional Janus nanobelts possess superior magnetic and fluorescent properties due to their special nanostructure. Compared with Fe3O4/Tb(BA)3phen/PMMA composite nanobelts, the magnetic-fluorescent bifunctional Janus nanobelts provided better performance. The new magnetic-fluorescent bifunctional Janus nanobelts have potential applications in novel nano-bio-label materials, drug target delivery materials and future nanodevices due to their excellent magnetic-fluorescent properties, flexibility and insolubility. Moreover, the construction technique for the Janus nanobelts is of universal significance for the fabrication of other multifunctional Janus nanobelts. Electronic supplementary information (ESI) available. See DOI: 10.1039/c3nr05472a

  2. AX-5 space suit bearing torque investigation

    NASA Technical Reports Server (NTRS)

    Loewenthal, Stuart; Vykukal, Vic; Mackendrick, Robert; Culbertson, Philip, Jr.

    1990-01-01

    The symptoms and eventual resolution of a torque increase problem occurring with ball bearings in the joints of the AX-5 space suit are described. Starting torques that rose 5 to 10 times initial levels were observed in crew evaluation tests of the suit in a zero-g water tank. This bearing problem was identified as a blocking torque anomaly, observed previously in oscillatory gimbal bearings. A large matrix of lubricants, ball separator designs and materials were evaluated. None of these combinations showed sufficient tolerance to lubricant washout when repeatedly cycled in water. The problem was resolved by retrofitting a pressure compensated, water exclusion seal to the outboard side of the bearing cavity. The symptoms and possible remedies to blocking are discussed.

  3. Physical properties of bifunctional BST/LSMO nanocomposites

    SciTech Connect

    Beltran-Huarac, Juan, E-mail: baristary26@gmail.com; Morell, Gerardo [Institute for Functional Nanomaterials, University of Puerto Rico, San Juan, Puerto Rico 00931 (United States); Department of Physics, University of Puerto Rico, Rio Piedras Campus, San Juan, Puerto Rico 00936 (United States); Martinez, Ricardo [Department of Mathematics and Physics, University of Puerto Rico, Cayey Campus, Cayey, Puerto Rico 00737 (United States)

    2014-02-28

    We report the fabrication of bifunctional nanocomposites consisting of ferroelectric Ba{sub 0.7}Sr{sub 0.3}TiO{sub 3} (BST) and ferromagnetic La{sub 0.67}Sr{sub 0.33}MnO{sub 3} (LSMO) at different concentrations via a high-temperature solid state route. The structural, dielectric, electrical, magnetodielectric (MD), magnetoelectric (ME) and magnetic properties of BST/LSMO nanocomposites were systematically investigated over a wide range of temperatures and frequencies. The X-Ray Diffraction analyses reveal the nanocrystalline nature of the heterostructures, wherein both perovskite phases co-exist. No parasitic phases were observed. The study of the dielectric properties shows that the nanocomposites exhibit relaxor ferroelectric character, with ferroelectric-paraelectric phase transition temperatures around 287–292?K that do not follow the Curie-Weiss law. The electrical measurements indicate that ac conductivities of the nanocomposites follow the Jonscher's universal power law, with activation energies of 0.42–0.63?eV based on Arrhenius-type behavior at high temperatures. The nanocomposites exhibit well-defined ferromagnetic hysteresis loops at room temperature (RT). The MD and ME measurements at RT indicate that BST/LSMO exhibits a nonlinear ME effect at low frequencies, with a threshold near 0.5?T. The magnetocapacitance (MC{sub p}) measurements evidence a quadratic dependence on magnetic field, further confirming the multiferroic nature of BST/LSMO. The order of MC{sub p} was found to be ?7% per Tesla. The analysis of the MC{sub p} measurements indicates that one of the BST/LSMO compositions studied can be considered as a new multiferroic compound.

  4. Grizzly bears and forestry

    Microsoft Academic Search

    S. E. Nielsen; R. H. M. Munro; E. L. Bainbridge; G. B. Stenhouse; M. S. Boyce

    2004-01-01

    We assessed the occurrence and fruit production of 13 grizzly bear foods in west-central Alberta, Canada, to better understand use of clearcuts by grizzly bears. Comparisons were made between clearcuts and upland forest stands, while specific models describing food or fruit occurrence within clearcuts were developed from canopy, clearcut age, scarification, and terrain-related variables using logistic regression. Ants, Equisetum spp.,

  5. Superconducting bearings in flywheels

    Microsoft Academic Search

    T. A. Coombs; A. M. Campbell; I. Ganney; W. Lo; T. Twardowski; B. Dawson

    1998-01-01

    Investigations are being carried out into the use of superconducting magnetic bearings to levitate Energy storage flywheels. In a planned program of work, Cambridge University are aiming to produce a practical bearing system for Pirouette™. The Pirouette™ system is designed to provide 5 kWh of recoverable energy which is currently recoverable at a rate of 5 kW (future revisions will

  6. Constructive optimisation criteria to increase bearing service life

    Microsoft Academic Search

    R. Grigorescu; M. D. Gafitanu

    2000-01-01

    For light mechanical structures, a bearing housing cannot be considered as rigid. Thus, rolling bearing rings are elastically\\u000a deformed under loading and lose their initial cylindrical shape. The load distribution among the rolling bodies is then modified,\\u000a which therefore affects the bearing life. In order to improve deficiencies in the existing models concerning the load distribution\\u000a in the case of

  7. Behaviour of solitary adult Scandinavian brown bears (Ursus arctos) when approached by humans on foot.

    PubMed

    Moen, Gro Kvelprud; Støen, Ole-Gunnar; Sahlén, Veronica; Swenson, Jon E

    2012-01-01

    Successful management has brought the Scandinavian brown bear (Ursus arctos L.) back from the brink of extinction, but as the population grows and expands the probability of bear-human encounters increases. More people express concerns about spending time in the forest, because of the possibility of encountering bears, and acceptance for the bear is decreasing. In this context, reliable information about the bear's normal behaviour during bear-human encounters is important. Here we describe the behaviour of brown bears when encountering humans on foot. During 2006-2009, we approached 30 adult (21 females, 9 males) GPS-collared bears 169 times during midday, using 1-minute positioning before, during and after the approach. Observer movements were registered with a handheld GPS. The approaches started 869±348 m from the bears, with the wind towards the bear when passing it at approximately 50 m. The bears were detected in 15% of the approaches, and none of the bears displayed any aggressive behaviour. Most bears (80%) left the initial site during the approach, going away from the observers, whereas some remained at the initial site after being approached (20%). Young bears left more often than older bears, possibly due to differences in experience, but the difference between ages decreased during the berry season compared to the pre-berry season. The flight initiation distance was longer for active bears (115±94 m) than passive bears (69±47 m), and was further affected by horizontal vegetation cover and the bear's age. Our findings show that bears try to avoid confrontations with humans on foot, and support the conclusions of earlier studies that the Scandinavian brown bear is normally not aggressive during encounters with humans. PMID:22363710

  8. Behaviour of Solitary Adult Scandinavian Brown Bears (Ursus arctos) when Approached by Humans on Foot

    PubMed Central

    Moen, Gro Kvelprud; Støen, Ole-Gunnar; Sahlén, Veronica; Swenson, Jon E.

    2012-01-01

    Successful management has brought the Scandinavian brown bear (Ursus arctos L.) back from the brink of extinction, but as the population grows and expands the probability of bear-human encounters increases. More people express concerns about spending time in the forest, because of the possibility of encountering bears, and acceptance for the bear is decreasing. In this context, reliable information about the bear's normal behaviour during bear-human encounters is important. Here we describe the behaviour of brown bears when encountering humans on foot. During 2006–2009, we approached 30 adult (21 females, 9 males) GPS-collared bears 169 times during midday, using 1-minute positioning before, during and after the approach. Observer movements were registered with a handheld GPS. The approaches started 869±348 m from the bears, with the wind towards the bear when passing it at approximately 50 m. The bears were detected in 15% of the approaches, and none of the bears displayed any aggressive behaviour. Most bears (80%) left the initial site during the approach, going away from the observers, whereas some remained at the initial site after being approached (20%). Young bears left more often than older bears, possibly due to differences in experience, but the difference between ages decreased during the berry season compared to the pre-berry season. The flight initiation distance was longer for active bears (115±94 m) than passive bears (69±47 m), and was further affected by horizontal vegetation cover and the bear's age. Our findings show that bears try to avoid confrontations with humans on foot, and support the conclusions of earlier studies that the Scandinavian brown bear is normally not aggressive during encounters with humans. PMID:22363710

  9. Bifunctional phosphoramidite reagents for the introduction of histidyl and dihistidyl residues into oligonucleotides.

    PubMed

    Smith, T H; LaTour, J V; Bochkariov, D; Chaga, G; Nelson, P S

    1999-01-01

    The synthesis and characterization of reagents for the incorporation of histidyl residues into oligonucleotides by automated chemical synthesis is described. Automated oligonucleotide synthesis utilizing a bifunctional reagent for the incorporation of a dihistidyl residue into oligonucleotides is described. Oligonucleotides incorporating one to three dihistidyl residues were prepared and characterized. The interaction of these oligonucleotides with a metal chelating IMAC matrix was explored. PMID:10411463

  10. Coated bifunctional catalysts for NO x SCR with C 3H 6

    Microsoft Academic Search

    Michael K. Neylon; Mario J. Castagnola; Norma B. Castagnola; Christopher L. Marshall

    2004-01-01

    Bifunctional catalysts comprising metal-exchange zeolites coated by metal oxides have been prepared and shown to be active catalysts for the selective catalytic reduction of NOx with propylene. Characterization of the materials by various means shows that oxide nano-particles adhere to the external surface of the zeolite and create a fine permeable coating which does not block the zeolite pores. When

  11. Bifunctional Lewis Acid-Nucleophile-Based Asymmetric Catalysis: Mechanistic Evidence for Imine Activation Working

    E-print Network

    Lectka, Thomas

    Bifunctional Lewis Acid-Nucleophile-Based Asymmetric Catalysis: Mechanistic Evidence for Imine. Chiral cinchona alkaloid derivatives work best when paired with Lewis acids based on Al(III), Zn(II), Sc catalysts (in this case a Lewis base and Lewis acid) are involved in the rate-determining step

  12. Janus nanobelts: fabrication, structure and enhanced magnetic-fluorescent bifunctional performance.

    PubMed

    Ma, Qianli; Yu, Wensheng; Dong, Xiangting; Wang, Jinxian; Liu, Guixia

    2014-03-01

    A new nanostructure of magnetic-fluorescent bifunctional Janus nanobelts with Fe3O4/PMMA as one half and Tb(BA)3phen/PMMA as the other half has been successfully fabricated by a specially designed parallel spinneret electrospinning technology. The morphology and properties of the final products were investigated in detail by X-ray diffractometry (XRD), scanning electron microscopy (SEM), energy dispersive spectrometry (EDS), biological microscopy (BM), vibrating sample magnetometry (VSM) and fluorescence spectroscopy. The results revealed that the [Fe3O4/PMMA]//[Tb(BA)3phen/PMMA] magnetic-fluorescent bifunctional Janus nanobelts possess superior magnetic and fluorescent properties due to their special nanostructure. Compared with Fe3O4/Tb(BA)3phen/PMMA composite nanobelts, the magnetic-fluorescent bifunctional Janus nanobelts provided better performance. The new magnetic-fluorescent bifunctional Janus nanobelts have potential applications in novel nano-bio-label materials, drug target delivery materials and future nanodevices due to their excellent magnetic-fluorescent properties, flexibility and insolubility. Moreover, the construction technique for the Janus nanobelts is of universal significance for the fabrication of other multifunctional Janus nanobelts. PMID:24480832

  13. Preparation of bi-functional silica particles for antibacterial and self cleaning surfaces.

    PubMed

    Hebalkar, Neha Y; Acharya, Snigdhatanu; Rao, Tata N

    2011-12-01

    Synthesis of bi-functional silica particles by a simple wet chemical method is described where the mixture of ultra fine nanoparticles (1-3 nm) of titania and silver were attached on the silica particle surface in a controlled way to form a core-shell structure. The silica surface showed efficient bi-functional activity of photo-catalytically self cleaning and antibacterial activity due to nanotitania and nanosilver mutually benefiting each other's function. The optimum silver concentration was found where extremely small silver nanoparticles are formed and the total composite particle remains white in color. This is an important property in view of certain applications such as antibacterial textiles where the original fabric color has to be retained even after applying the nanosilver on it. The particles were characterized at each step of the synthesis by X-ray photoelectron spectroscopy, UV-visible spectroscopy, X-ray diffraction, scanning electron microscopy, transmission electron microscopy and electron energy loss spectroscopy. Bi-functional silica particles showed accelerated photocatalytic degradation of methylene blue as well as enhanced antibacterial property when tested as such particles and textiles coated with these bi-functional silica particles even at lower silver concentration. PMID:21889161

  14. Catalysis Today 67 (2001) 341355 Combinatorial discovery of bifunctional oxygen reduction --

    E-print Network

    2001-01-01

    oxidation electrocatalysts for regenerative fuel cells Guoying Chena, David A. Delafuentea, S. Sarangapanib cell; Regenerative fuel cell; Electrocatalyst; Bifunctional catalyst; Combinatorial; Water oxidation the oxidative deprotonation of S­OH groups. © 2001 Elsevier Science B.V. All rights reserved. Keywords: Fuel

  15. Effect of fabrication methods of bifunctional catalyst layers on unitized regenerative fuel cell performance

    Microsoft Academic Search

    Guobao Chen; Huamin Zhang; Haipeng Ma; Hexiang Zhong

    2009-01-01

    In order to understand the origins of performance variations in unitized regenerative fuel cells (URFCs), bifunctional catalyst layers (BCLs) fabricated with two different methods, i.e., ink deposition on membrane or GDL, were designed in this paper. The performances of the two different methods were evaluated, and their reaction dynamics were measured by electrochemical impedance spectra. The different BCLs, caused by

  16. Catalytic Asymmetric Peroxidation of ?,?-Unsaturated Nitroalkenes by a Bifunctional Organic Catalyst

    PubMed Central

    2015-01-01

    A new enantioselective peroxidation of ?,?-unsaturated nitroalkenes was realized with an easily accessible acid–base bifunctional organic catalyst derived from cinchona alkaloids. This reaction provides unprecedented easy access to optically active chiral peroxides, as illustrated by the asymmetric synthesis of ?-peroxy nitro compounds. PMID:24730647

  17. The soluble epoxide hydrolase encoded by EPXH2 is a bifunctional enzyme with novel lipid phosphate

    E-print Network

    Hammock, Bruce D.

    The soluble epoxide hydrolase encoded by EPXH2 is a bifunctional enzyme with novel lipid phosphate for the soluble epoxide hydrolase (sEH), an enzyme involved in the regulation of cardiovascular and renal definitively reported. In this study we describe the N-terminal domain as a functional phosphatase unaffected

  18. Residues Involved in the Mechanism of the Bifunctional Methylenetetrahydrofolate Dehydrogenase-Cyclohydrolase

    E-print Network

    Verbrugge, Clark

    -Cyclohydrolase THE ROLES OF GLUTAMINE 100 AND ASPARTATE 125* Received for publication, January 5, 2002, and in revised form, McGill University, Montreal, Quebec H3G 1Y6, Canada The human bifunctional dehydrogenase the role of lysine 56, the work presented in this study explores the func- tions of glutamine 100

  19. Ball Bearing Mechanics

    NASA Technical Reports Server (NTRS)

    Hamrock, B. J.; Dowson, D.

    1981-01-01

    Load-deflection relationships for different types of elliptical contacts such as those found in a ball bearing are developed. Simplified expressions that allow quick calculations of deformation to be made simply from a knowledge of the applied load, the material properties, and the geometry of the contacting elements are presented. Ball bearings subjected to radial, thrust and combined ball loads are analyzed. A design criterion for fatigue life of ball bearings is developed. The section of a satisfactory lubricant, as well as describing systems that provide a constant flow of lubricant to the contact, is considered.

  20. The Polar Bear Tracker

    NSDL National Science Digital Library

    This new Web site from the World Wildlife Fund (WWF) International explores how polar bears are affected by global warming. Data on the movements of two radio-collared bears can be viewed, along with the ice status, through a series of online maps. This is an interesting site with valuable information and a nice balance of maps, photos, and text. The animation of the polar bear tracking data is a really neat feature, but is best viewed by advancing through the stages manually because the rapid speed of the film makes it difficult to comprehend.

  1. Rocketdyne LOX bearing tester program

    NASA Technical Reports Server (NTRS)

    Keba, J. E.; Beatty, R. F.

    1988-01-01

    The cause, or causes, for the Space Shuttle Main Engine ball wear were unknown, however, several mechanisms were suspected. Two testers were designed and built for operation in liquid oxygen to empirically gain insight into the problems and iterate solutions in a timely and cost efficient manner independent of engine testing. Schedules and test plans were developed that defined a test matrix consisting of parametric variations of loading, cooling or vapor margin, cage lubrication, material, and geometry studies. Initial test results indicated that the low pressure pump thrust bearing surface distress is a function of high axial load. Initial high pressure turbopump bearing tests produced the wear phenomenon observed in the turbopump and identified an inadequate vapor margin problem and a coolant flowrate sensitivity issue. These tests provided calibration data of analytical model predictions to give high confidence in the positive impact of future turbopump design modification for flight. Various modifications will be evaluated in these testers, since similar turbopump conditions can be produced and the benefit of the modification will be quantified in measured wear life comparisons.

  2. Investigation of Pressurized Wave Bearings

    NASA Technical Reports Server (NTRS)

    Keith, Theo G., Jr.; Dimofte, Florin

    2003-01-01

    The wave bearing has been pioneered and developed by Dr. Dimofte over the past several years. This bearing will be the main focus of this research. It is believed that the wave bearing offers a number of advantages over the foil bearing, which is the bearing that NASA is currently pursuing for turbomachinery applications. The wave bearing is basically a journal bearing whose film thickness varies around the circumference approximately sinusoidally, with usually 3 or 4 waves. Being a rigid geometry bearing, it provides precise control of shaft centerlines. The wave profile also provides good load capacity and makes the bearing very stable. Manufacturing techniques have been devised that should allow the production of wave bearings almost as cheaply as conventional full-circular bearings.

  3. Optimal Synchronizability of Bearings

    NASA Astrophysics Data System (ADS)

    Araújo, N. A. M.; Seybold, H.; Baram, R. M.; Herrmann, H. J.; Andrade, J. S., Jr.

    2013-02-01

    Bearings are mechanical dissipative systems that, when perturbed, relax toward a synchronized (bearing) state. Here we find that bearings can be perceived as physical realizations of complex networks of oscillators with asymmetrically weighted couplings. Accordingly, these networks can exhibit optimal synchronization properties through fine-tuning of the local interaction strength as a function of node degree [Motter, Zhou, and Kurths, Phys. Rev. E 71, 016116 (2005)PLEEE81539-3755]. We show that, in analogy, the synchronizability of bearings can be maximized by counterbalancing the number of contacts and the inertia of their constituting rotor disks through the mass-radius relation, m˜r?, with an optimal exponent ?=?× which converges to unity for a large number of rotors. Under this condition, and regardless of the presence of a long-tailed distribution of disk radii composing the mechanical system, the average participation per disk is maximized and the energy dissipation rate is homogeneously distributed among elementary rotors.

  4. PCs and Polar Bears

    NSDL National Science Digital Library

    Jessica Fries-Gaither

    2011-01-01

    This article looks at the growing energy consumption from consumer electronics and the increases it may cause in greenhouse gases and global warming. The article appears in the free, online magazine Beyond Penguins and Polar Bears.

  5. Gear bearing drive

    NASA Technical Reports Server (NTRS)

    Weinberg, Brian (Inventor); Mavroidis, Constantinos (Inventor); Vranish, John M. (Inventor)

    2011-01-01

    A gear bearing drive provides a compact mechanism that operates as an actuator providing torque and as a joint providing support. The drive includes a gear arrangement integrating an external rotor DC motor within a sun gear. Locking surfaces maintain the components of the drive in alignment and provide support for axial loads and moments. The gear bearing drive has a variety of applications, including as a joint in robotic arms and prosthetic limbs.

  6. Load responsive hydrodynamic bearing

    DOEpatents

    Kalsi, Manmohan S. (Houston, TX); Somogyi, Dezso (Sugar Land, TX); Dietle, Lannie L. (Stafford, TX)

    2002-01-01

    A load responsive hydrodynamic bearing is provided in the form of a thrust bearing or journal bearing for supporting, guiding and lubricating a relatively rotatable member to minimize wear thereof responsive to relative rotation under severe load. In the space between spaced relatively rotatable members and in the presence of a liquid or grease lubricant, one or more continuous ring shaped integral generally circular bearing bodies each define at least one dynamic surface and a plurality of support regions. Each of the support regions defines a static surface which is oriented in generally opposed relation with the dynamic surface for contact with one of the relatively rotatable members. A plurality of flexing regions are defined by the generally circular body of the bearing and are integral with and located between adjacent support regions. Each of the flexing regions has a first beam-like element being connected by an integral flexible hinge with one of the support regions and a second beam-like element having an integral flexible hinge connection with an adjacent support region. A least one local weakening geometry of the flexing region is located intermediate the first and second beam-like elements. In response to application of load from one of the relatively rotatable elements to the bearing, the beam-like elements and the local weakening geometry become flexed, causing the dynamic surface to deform and establish a hydrodynamic geometry for wedging lubricant into the dynamic interface.

  7. Simulation of Rolling Element Bearings

    Microsoft Academic Search

    Lars-Erik Stacke; Dag Fritzson

    Rolling bearings are high precision, low cost machine elements, used in all kinds of rotat- ing machinery. Simulations of rolling bear- ings bring increased understanding of their dy- namic behaviour, and shortens product develop- ment time. A rolling bearing simulation model called BEAST (BEAring Simulation Tool), has been developed by SKF. Due to the high demands on contact geometry description

  8. Simple modeling of hydrostatic bearings

    NASA Astrophysics Data System (ADS)

    Hull, Charlie

    2014-07-01

    Hydrostatic bearings are a key component for many large telescopes due to their high load bearing capacity, stiffness and low friction. A simple technique is presented to model these bearings to understand the effects of geometry, oil viscosity, flow control, temperature, etc. on the bearings behavior.

  9. Developmental and pathological expression of peroxisomal enzymes: their relationship of d-bifunctional protein deficiency and Zellweger syndrome

    Microsoft Academic Search

    Masayuki Itoh; Yasuyuki Suzuki; Shinjiro Akaboshi; Zhongyi Zhang; Shinichi Miyabara; Sachio Takashima

    2000-01-01

    We present the developmental changes of peroxisomal enzymes, catalase, l-bifunctional protein (l-BF) and d-bifunctional protein (d-BF), in the normal brains, and patients with d-BF deficiency, a new peroxisomal disease. d-BF immunoreactivity was observed in controls as early as 13 gestational weeks (GW) and increased with maturation. The adult pattern with fine granule staining of somata and dendrites became apparent in

  10. Square Root Iterated Kalman Filter for Bearing-Only SLAM Hyungpil Moon, George Kantor, Howie Choset

    E-print Network

    Choset, Howie

    Square Root Iterated Kalman Filter for Bearing-Only SLAM Hyungpil Moon, George Kantor, Howie Choset an undelayed solution to the bearing-only simultaneous localization and mapping problem (SLAM). We employ existing bearing- only algorithms focus on proper initialization of landmark locations, our method allows

  11. Iterated Filters for Bearing-Only SLAM Stephen Tully, Hyungpil Moon, George Kantor, and Howie Choset

    E-print Network

    Choset, Howie

    Iterated Filters for Bearing-Only SLAM Stephen Tully, Hyungpil Moon, George Kantor, and Howie step for the problem of bearing-only SLAM. We focus on an undelayed approach that initializes a landmark after only one bearing measurement. Traditionally, the extended Kalman filter (EKF) has been used

  12. 49 CFR 40.385 - Who bears the burden of proof in a PIE proceeding?

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ...2010-10-01 2010-10-01 false Who bears the burden of proof in a PIE proceeding...Interest Exclusions § 40.385 Who bears the burden of proof in a PIE proceeding...issuing a PIE, the initiating official bears the burden of proof. (b) This...

  13. 49 CFR 40.385 - Who bears the burden of proof in a PIE proceeding?

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ...2011-10-01 2011-10-01 false Who bears the burden of proof in a PIE proceeding...Interest Exclusions § 40.385 Who bears the burden of proof in a PIE proceeding...issuing a PIE, the initiating official bears the burden of proof. (b) This...

  14. Occurrence of brittle flaking on bearings used for automotive electrical instruments and auxiliary devices

    Microsoft Academic Search

    K. Tamada; H. Tanaka

    1996-01-01

    The higher transmission efficiency of engine accessory drive belts has resulted in a new type of bearing damage, called “brittle flaking” by NTN. This new type of bearing damage has been observed in bearings used in automotive electrical instruments and auxiliary devices. This paper summarizes recent test results which clarify the initiation mechanism of the brittle flaking damage.the type of

  15. Sinorhizobium meliloti flavin secretion and bacteria-host interaction: role of the bifunctional RibBA protein.

    PubMed

    Yurgel, Svetlana N; Rice, Jennifer; Domreis, Elizabeth; Lynch, Joseph; Sa, Na; Qamar, Zeeshan; Rajamani, Sathish; Gao, Mengsheng; Roje, Sanja; Bauer, Wolfgang D

    2014-05-01

    Sinorhizobium meliloti, the nitrogen-fixing bacterial symbiont of Medicago spp. and other legumes, secretes a considerable amount of riboflavin. This precursor of the cofactors flavin mononucleotide and flavin adenine dinucleotide is a bioactive molecule that has a beneficial effect on plant growth. The ribBA gene of S. meliloti codes for a putative bifunctional enzyme with dihydroxybutanone phosphate synthase and guanosine triphosphate (GTP) cyclohydrolase II activities, catalyzing the initial steps of the riboflavin biosynthesis pathway. We show here that an in-frame deletion of ribBA does not cause riboflavin auxotrophy or affect the ability of S. meliloti to establish an effective symbiosis with the host plant but does affect the ability of the bacteria to secrete flavins, colonize host-plant roots, and compete for nodulation. A strain missing the RibBA protein retains considerable GTP cyclohydrolase II activity. Based on these results, we hypothesize that S. meliloti has two partly interchangeable modules for biosynthesis of riboflavin, one fulfilling the internal need for flavins in bacterial metabolism and the other producing riboflavin for secretion. Our data also indicate that bacteria-derived flavins play a role in communication between rhizobia and the legume host and that the RibBA protein is important in this communication process even though it is not essential for riboflavin biosynthesis and symbiosis. PMID:24405035

  16. Partial tooth gear bearings

    NASA Technical Reports Server (NTRS)

    Vranish, John M. (Inventor)

    2010-01-01

    A partial gear bearing including an upper half, comprising peak partial teeth, and a lower, or bottom, half, comprising valley partial teeth. The upper half also has an integrated roller section between each of the peak partial teeth with a radius equal to the gear pitch radius of the radially outwardly extending peak partial teeth. Conversely, the lower half has an integrated roller section between each of the valley half teeth with a radius also equal to the gear pitch radius of the peak partial teeth. The valley partial teeth extend radially inwardly from its roller section. The peak and valley partial teeth are exactly out of phase with each other, as are the roller sections of the upper and lower halves. Essentially, the end roller bearing of the typical gear bearing has been integrated into the normal gear tooth pattern.

  17. Radial Halbach Magnetic Bearings

    NASA Technical Reports Server (NTRS)

    Eichenberg, Dennis J.; Gallo, Christopher A.; Thompson, William K.

    2009-01-01

    Radial Halbach magnetic bearings have been investigated as part of an effort to develop increasingly reliable noncontact bearings for future high-speed rotary machines that may be used in such applications as aircraft, industrial, and land-vehicle power systems and in some medical and scientific instrumentation systems. Radial Halbach magnetic bearings are based on the same principle as that of axial Halbach magnetic bearings, differing in geometry as the names of these two types of bearings suggest. Both radial and axial Halbach magnetic bearings are passive in the sense that unlike most other magnetic bearings that have been developed in recent years, they effect stable magnetic levitation without need for complex active control. Axial Halbach magnetic bearings were described in Axial Halbach Magnetic Bearings (LEW-18066-1), NASA Tech Briefs, Vol. 32, No. 7 (July 2008), page 85. In the remainder of this article, the description of the principle of operation from the cited prior article is recapitulated and updated to incorporate the present radial geometry. In simplest terms, the basic principle of levitation in an axial or radial Halbach magnetic bearing is that of the repulsive electromagnetic force between (1) a moving permanent magnet and (2) an electric current induced in a stationary electrical conductor by the motion of the magnetic field. An axial or radial Halbach bearing includes multiple permanent magnets arranged in a Halbach array ("Halbach array" is defined below) in a rotor and multiple conductors in the form of wire coils in a stator, all arranged so the rotary motion produces an axial or radial repulsion that is sufficient to levitate the rotor. A basic Halbach array (see Figure 1) consists of a row of permanent magnets, each oriented so that its magnetic field is at a right angle to that of the adjacent magnet, and the right-angle turns are sequenced so as to maximize the magnitude of the magnetic flux density on one side of the row while minimizing it on the opposite side. The advantage of this configuration is that it makes it possible to approach the theoretical maximum force per unit area that could be exerted by a given amount of permanent-magnet material. The configuration is named after physicist Klaus Halbach, who conceived it for use in particle accelerators. Halbach arrays have also been studied for use in magnetic-levitation ("maglev") railroad trains. In a radial Halbach magnetic bearing, the basic Halbach arrangement is modified into a symmetrical arrangement of sector-shaped permanent magnets mounted on the outer cylindrical surface of a drum rotor (see Figure 2). The magnets are oriented to concentrate the magnetic field on their radially outermost surface. The stator coils are mounted in a stator shell surrounding the rotor.

  18. Blood Pump Bearing System

    NASA Technical Reports Server (NTRS)

    Aber, Gregory S. (Inventor)

    2000-01-01

    An apparatus is provided for a blood pump bearing system within a pump housing to support long-term highspeed rotation of a rotor with an impeller blade having a plurality of individual magnets disposed thereon to provide a small radial air gap between the magnets and a stator of less than 0.025 inches. The bearing system may be mounted within a flow straightener, diffuser, or other pump element to support the shaft of a pump rotor. The bearing system includes a zirconia shaft having a radiused end. The radiused end has a first radius selected to be about three times greater than the radius of the zirconia shaft. The radiused end of the zirconia shaft engages a flat sapphire endstone. Due to the relative hardness of these materials a flat is quickly produced during break-in on the zirconia radiused end of precisely the size necessary to support thrust loads whereupon wear substantially ceases. Due to the selection of the first radius, the change in shaft end-play during pump break-in is limited to a total desired end-play of less than about 0.010 inches. Radial loads are supported by an olive hole ring jewel that makes near line contact around the circumference of the Ir shaft to support big speed rotation with little friction. The width of olive hole ring jewel is small to allow heat to conduct through to thereby prevent heat build-up in the bearing. A void defined by the bearing elements may fill with blood that then coagulates within the void. The coagulated blood is then conformed to the shape of the bearing surfaces.

  19. Blood Pump Bearing System

    NASA Technical Reports Server (NTRS)

    Aber, Gregory S. (Inventor)

    1999-01-01

    Methods and apparatus are provided for a blood pump bearing system within a pump housing to support long-term high-speed rotation of a rotor with an impeller blade having a plurality of individual magnets disposed thereon to provide a small radial air gap between the magnets and a stator of less than 0.025 inches. The bearing system may be mounted within a flow straightener, diffuser, or other pump element to support the shaft of a pump rotor. The bearing system includes a zirconia shaft having a radiused end. The radiused end has a first radius selected to be about three times greater than the radius of the zirconia shaft. The radiused end of the zirconia shaft engages a flat sapphire endstone. Due to the relative hardness of these materials a flat is quickly produced during break-in on the zirconia radiused end of precisely the size necessary to support thrust loads whereupon wear substantially ceases. Due to the selection of the first radius, the change in shaft end-play during pump break-in is limited to a total desired end-play of less than about 0.010 inches. Radial loads are supported by an olive hole ring jewel that makes near line contact around the circumference of the shaft to support high speed rotation with little friction. The width of olive hole ring jewel is small to allow heat to conduct through to thereby prevent heat build-up in the bearing. A void defined by the bearing elements may fill with blood that then coagulates within the void. The coagulated blood is then conformed to the shape of the bearing surfaces.

  20. Comparative analysis of smart bearing sensors

    NASA Astrophysics Data System (ADS)

    Matre, Jeffrey S.; Wahrmund, John C.; Waters, Donald P.

    1998-07-01

    Currently, the Air Force's fleet of aircraft, and helicopters in particular, are aging. These aircraft are nearing the end of their design life, but are being required to continue service well into the next century. In an attempt to help extend the life of these aircraft, the area of health monitoring has received considerable interest. In the case of the MH-53J PAVE LOW, this health monitoring has taken the form of vibration monitoring. The initial effort at health monitoring has consisted of placing accelerometers on the bearing support brackets for the tail rotor drive shaft. The results of this monitoring have provided information that allows the maintainers to replace the bearings only when the bearing is showing signs of wear rather than at a given interval. Additionally, the data has been used to make near real time evaluations of the airworthiness of the aircraft. The result has been a decrease of 50% in the number of missions canceled due to vibration related issues. The Air Force is looking at expanding the present vibration monitoring system to the entire fleet of MH-53J aircraft. In conjunction with this expansion, this paper looks at evaluating a transducer specifically designed for monitoring bearings. A comparison between accelerometer responses and the bearing transducer response is made.

  1. Preparations of bifunctional polymeric beads simultaneously incorporated with fluorescent quantum dots and magnetic nanocrystals

    NASA Astrophysics Data System (ADS)

    Tu, Chifeng; Yang, Yunhua; Gao, Mingyuan

    2008-03-01

    Bifunctional polystyrene beads simultaneously incorporated with fluorescent CdTe quantum dots (Q-dots) and superparamagnetic Fe3O4 nanocrystals were prepared by a modified mini-emulsion polymerization method, in which polymerizable surfactants were used as both phase transfer agent for aqueous colloidal nanoparticles and emulsifier. In addition, silica coating was also introduced to Fe3O4 nanocrystals for regulating the internal structure of the composite beads. Transmission electron microscopy, confocal fluorescence microscopy and conventional spectroscopy were used to characterize the composite beads, as well as the polymerizable surfactant-coated CdTe Q-dots and silica-coated Fe3O4 nanoparticles. Different mixing methods were also attempted in order to vary the size of the resultant bifunctional beads.

  2. Biochemical characterization and structural analysis of a bifunctional cellulase/xylanase from Clostridium thermocellum.

    PubMed

    Yuan, Shuo-Fu; Wu, Tzu-Hui; Lee, Hsiao-Lin; Hsieh, Han-Yu; Lin, Wen-Ling; Yang, Barbara; Chang, Chih-Kang; Li, Qian; Gao, Jian; Huang, Chun-Hsiang; Ho, Meng-Chiao; Guo, Rey-Ting; Liang, Po-Huang

    2015-02-27

    We expressed an active form of CtCel5E (a bifunctional cellulase/xylanase from Clostridium thermocellum), performed biochemical characterization, and determined its apo- and ligand-bound crystal structures. From the structures, Asn-93, His-168, His-169, Asn-208, Trp-347, and Asn-349 were shown to provide hydrogen-bonding/hydrophobic interactions with both ligands. Compared with the structures of TmCel5A, a bifunctional cellulase/mannanase homolog from Thermotoga maritima, a flexible loop region in CtCel5E is the key for discriminating substrates. Moreover, site-directed mutagenesis data confirmed that His-168 is essential for xylanase activity, and His-169 is more important for xylanase activity, whereas Asn-93, Asn-208, Tyr-270, Trp-347, and Asn-349 are critical for both activities. In contrast, F267A improves enzyme activities. PMID:25575592

  3. Radiometals (non-Tc, non-Re) and Bifunctional Labeling Chemistry

    NASA Astrophysics Data System (ADS)

    Fani, M.; Good, S.; Maecke, H. R.

    Radiometals are of increased current interest because of the growing use of targeted radiotherapy for tumors and the development of generators that produce positron-emitting radiometals. In addition, biomedical cyclotrons allow the cheap production of some relevant radiometals. The design of the corresponding radiopharmaceuticals includes the synthesis of bifunctional chelators, which carry a functional unit for the immobilization of the radiometal and a functional group for the covalent attachment to a vector molecule. Radiometals of interest for therapeutic applications are some lanthanides, 67Cu, and 90Y. For diagnostic applications 61Cu, 62Cu, 64Cu, 89Zr, and 68Ga are currently used and corresponding radiopharmaceuticals are being designed. In this chapter, some properties and the synthesis of bifunctional chelators including metal ion selectivity and special aspects of coupling chemistry are being described.

  4. Purification, characterization, and identification of a novel bifunctional catalase-phenol oxidase from Scytalidium thermophilum

    Microsoft Academic Search

    Didem Sutay Kocabas; Ufuk Bakir; Simon E. V. Phillips; Michael J. McPherson; Zumrut B. Ogel

    2008-01-01

    A novel bifunctional catalase with an additional phenol oxidase activity was isolated from a thermophilic fungus, Scytalidium thermophilum. This extracellular enzyme was purified ca. 10-fold with 46% yield and was biochemically characterized. The enzyme contains\\u000a heme and has a molecular weight of 320 kDa with four 80 kDa subunits and an isoelectric point of 5.0. Catalase and phenol\\u000a oxidase activities were most

  5. Bifunctional hydrogel coatings for water purification membranes: Improved fouling resistance and antimicrobial activity

    Microsoft Academic Search

    Young-Hye La; Bryan D. McCloskey; Ratnam Sooriyakumaran; Ankit Vora; Benny Freeman; Majed Nassar; James Hedrick; Alshakim Nelson; Robert Allen

    2011-01-01

    Bifunctional hydrogel materials having both fouling resistance and antimicrobial activity were prepared by the photopolymerization of polyethylene glycol diacrylate (PEGDA) and a functional monomer containing ammonium salt (RNH3Cl) in the presence of a photoinitiator. Water was added to the prepolymerization mixture to increase the solubility of the RNH3Cl monomer and to control the cross-linking density of the UV-cured films. The

  6. Bifunctional redox flow battery-1 V(III)\\/V(II)–glyoxal(O 2) system

    Microsoft Academic Search

    Y. H. Wen; J. Cheng; P. H. Ma; Y. S. Yang

    2008-01-01

    Bifunctional redox flow batteries (BRFB) possess functions of both electricity storage and electrochemical preparation, having the potential for increasing the electrical energy utilization. A V(III)\\/V(II)–glyoxal(O2) system has been developed. Separators of the BRFB play a key role in BRFB performance. A Nafion solution was sprayed on a gas diffusion layer (GDL) at the Nafion loading of 2mgcm?2, and the GDL

  7. Synthesis of acid-base bifunctional mesoporous materials by oxidation and thermolysis

    SciTech Connect

    Yu, Xiaofang [College of Chemistry, Jilin University, Jiefang Road 2519, Changchun 130023 (China)] [College of Chemistry, Jilin University, Jiefang Road 2519, Changchun 130023 (China); Zou, Yongcun [State Key Laboratory of Inoranic Synthesis and Preparative Chemistryg, College of Chemistry, Jilin University, Changchun 130012 (China)] [State Key Laboratory of Inoranic Synthesis and Preparative Chemistryg, College of Chemistry, Jilin University, Changchun 130012 (China); Wu, Shujie; Liu, Heng [College of Chemistry, Jilin University, Jiefang Road 2519, Changchun 130023 (China)] [College of Chemistry, Jilin University, Jiefang Road 2519, Changchun 130023 (China); Guan, Jingqi, E-mail: guanjq@jlu.edu.cn [College of Chemistry, Jilin University, Jiefang Road 2519, Changchun 130023 (China)] [College of Chemistry, Jilin University, Jiefang Road 2519, Changchun 130023 (China); Kan, Qiubin, E-mail: qkan@jlu.edu.cn [College of Chemistry, Jilin University, Jiefang Road 2519, Changchun 130023 (China)] [College of Chemistry, Jilin University, Jiefang Road 2519, Changchun 130023 (China)

    2011-06-15

    Graphical abstract: A novel and efficient method has been developed for the synthesis of acid-base bifunctional catalyst. The obtained sample of SO{sub 3}H-MCM-41-NH{sub 2} containing amine and sulfonic acids exhibits excellent catalytic activity in aldol condensation reaction. Research highlights: {yields} Synthesize acid-base bifunctional mesoporous materials SO{sub 3}H-MCM-41-NH{sub 2}. {yields} Oxidation and then thermolysis to generate acidic site and basic site. {yields} Exhibit good catalytic performance in aldol condensation reaction between acetone and various aldehydes. -- Abstract: A novel and efficient method has been developed for the synthesis of acid-base bifunctional catalyst SO{sub 3}H-MCM-41-NH{sub 2}. This method was achieved by co-condensation of tetraethylorthosilicate (TEOS), 3-mercaptopropyltrimethoxysilane (MPTMS) and (3-triethoxysilylpropyl) carbamicacid-1-methylcyclohexylester (3TAME) in the presence of cetyltrimethylammonium bromide (CTAB), followed by oxidation and then thermolysis to generate acidic site and basic site. X-ray diffraction (XRD) and transmission electron micrographs (TEM) show that the resultant materials keep mesoporous structure. Thermogravimetric analysis (TGA), X-ray photoelectron spectra (XPS), back titration, solid-state {sup 13}C CP/MAS NMR and solid-state {sup 29}Si MAS NMR confirm that the organosiloxanes were condensed as a part of the silica framework. The bifunctional sample (SO{sub 3}H-MCM-41-NH{sub 2}) containing amine and sulfonic acids exhibits excellent acid-basic properties, which make it possess high activity in aldol condensation reaction between acetone and various aldehydes.

  8. Bifunctional oxygen electrode with corrosion-resistive gas diffusion layer for unitized regenerative fuel cell

    Microsoft Academic Search

    Shidong Song; Huamin Zhang; Xiaoping Ma; Zhi-Gang Shao; Yining Zhang; Baolian Yi

    2006-01-01

    To develop the unitized regenerative fuel cell (URFC) with low cost and high performance, a novel bifunctional oxygen electrode with a thin-film electrocatalyst layer and a corrosion-resistive gas diffusion layer (GDL) prepared by the carbon paper backing and a protective micro-porous layer (MPL) was developed. The protective MPL was made of the IrO2 deposited fine Ti powders. The cycle performance

  9. The improved performance of dye sensitized solar cells by bifunctional aminosilane modified dye sensitized photoanode

    Microsoft Academic Search

    Jing Zhang; Guangtao Yang; Qiang Sun; Jun Zheng; Peiqing Wang; Yuejin Zhu; Xingzhong Zhao

    2010-01-01

    The dye sensitized photoanode is modified by the bifunctional 3-aminopropyltriethoxysilane (APTS). The attenuated total reflection–Fourier transform infrared spectroscopy, the UV-IR spectroscopy, the dye adsorption amount, and the electrochemical impedance spectroscopy were carried out to examine the modification effect. The experiments indicated that the APTS with amino endgroup and triethoxysilane group deprotonated the surface of the dye sensitized photoanode and formed

  10. Activation of C 2–C 4 alkanes over acid and bifunctional zeolite catalysts

    Microsoft Academic Search

    G. Caeiro; R. H. Carvalho; X. Wang; M. A. N. D. A. Lemos; F. Lemos; M. Guisnet; F. Ramôa Ribeiro

    2006-01-01

    This review paper presents the significant advances which were made in the last decade in the understanding of the transformation over acid and bifunctional zeolite catalysts of the cheap and readily available C2–C4 alkanes into more valuable products: mechanism of activation, reaction scheme, nature of the active sites. Both the transformations of pure alkanes: n-butane isomerization, C2–C4 alkane aromatization and

  11. Bifunctional ligands in combination with phosphines and Lewis acidic phospheniums for the carbonylative Sonogashira reaction.

    PubMed

    Tan, Chen; Wang, Peng; Liu, Huan; Zhao, Xiao-Li; Lu, Yong; Liu, Ye

    2015-06-23

    The combination of phosphine-ligated Pd catalysis and phosphenium(v) Lewis acid catalysis has been developed for the carbonylative Sonogashira reaction using phosphino-phosphenium salts () as bifunctional ligands, in which the Lewis acidic phosphenium(v) cations can form secondary bonds with O atoms (in C[double bond, length as m-dash]O) to cooperatively stabilize Pd-acyl intermediates. PMID:26055388

  12. Efficient Synthesis of Octahydrophenanthrene Derivatives with Mild Cascade Reactions of Isochromenylium Tetrafluoroborates and Bifunctional Styrenes.

    PubMed

    Mo, Lei; Wu, Lin-Lin; Wang, Shaozhong; Yao, Zhu-Jun

    2015-07-01

    A highly efficient catalyst-free cascade reaction of air-stable isochromenylium tetrafluoroborates and bifunctional styrenes containing a 1,3-diketone moiety has been developed, affording the corresponding single diastereomeric ocatahydrophenanthrene derivatives (21 examples, up to 86% yield). A cascade process of [4 + 2]-cyclization and subsequent intramolecular nucleophilic addition is proposed to generate the three new C-C bonds diastereoselectively in the reactions. PMID:26098712

  13. Bearing-Cartridge Damping Seal

    NASA Technical Reports Server (NTRS)

    Goggins, David G.; Scharrer, Joseph K.; Chen, Wei C.

    1991-01-01

    In proposed design for improved ball-bearing cartridge, damping seal in form of thin-layer fluid journal bearing incorporated into cartridge. Damping seal acts as auxiliary bearing, relieving bearing balls of significant portions of both static and dynamic bearing loads. Damping from seal reduces dynamic loads even further by reducing amplitude of vibrations in second vibrational mode of rotor, which mode occurs when rotor turning at nearly full operating speed. Intended for use in high-pressure-oxygen turbopump of Space Shuttle main engine, also applicable to other turbomachinery bearings.

  14. Development of Cobalt Hydroxide as a Bifunctional Catalyst for Oxygen Electrocatalysis in Alkaline Solution.

    PubMed

    Zhan, Yi; Du, Guojun; Yang, Shiliu; Xu, Chaohe; Lu, Meihua; Liu, Zhaolin; Lee, Jim Yang

    2015-06-17

    Co(OH)2 in the form of hexagonal nanoplates synthesized by a simple hydrothermal reaction has shown even greater activity than cobalt oxides (CoO and Co3O4) in oxygen reduction and oxygen evolution reactions (ORR and OER) under alkaline conditions. The bifunctionality for oxygen electrocatalysis as shown by the OER-ORR potential difference (?E) could be reduced to as low as 0.87 V, comparable to the state-of-the-art non-noble bifunctional catalysts, when the Co(OH)2 nanoplates were compounded with nitrogen-doped reduced graphene oxide (N-rGO). The good performance was attributed to the nanosizing of Co(OH)2 and the synergistic interaction between Co(OH)2 and N-rGO. A zinc-air cell assembled with a Co(OH)2-air electrode also showed a performance comparable to that of the state-of-the-art zinc-air cells. The combination of bifunctional activity and operational stability establishes Co(OH)2 as an effective low-cost alternative to the platinum group metal catalysts. PMID:25997179

  15. Gearbox Reliability Collaborative Bearing Calibration

    SciTech Connect

    van Dam, J.

    2011-10-01

    NREL has initiated the Gearbox Reliability Collaborative (GRC) to investigate the root cause of the low wind turbine gearbox reliability. The GRC follows a multi-pronged approach based on a collaborative of manufacturers, owners, researchers and consultants. The project combines analysis, field testing, dynamometer testing, condition monitoring, and the development and population of a gearbox failure database. At the core of the project are two 750kW gearboxes that have been redesigned and rebuilt so that they are representative of the multi-megawatt gearbox topology currently used in the industry. These gearboxes are heavily instrumented and are tested in the field and on the dynamometer. This report discusses the bearing calibrations of the gearboxes.

  16. 10. DETAIL VIEW OF END BEARING CONDITION SHOWING MOVEABLE BEARING ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    10. DETAIL VIEW OF END BEARING CONDITION SHOWING MOVEABLE BEARING AT SOUTHEAST END OF LOWER ROAD LEVEL - Mahoning Avenue Pratt Double-Deck Bridge, Spanning Mill Creek at Mahoning Avenue (C.R. 319), Youngstown, Mahoning County, OH

  17. Totally frictionless magnetic bearing

    Microsoft Academic Search

    Wayne Dodakian; John Bulman

    2000-01-01

    A totally frictionless magnetic bearing has been developed which supports a rotor in a contactless manner. The rotor is held in a magnetic potential well via repulsive forces only. Vertical and lateral restoring forces are provided to the rotor passively via permanent magnets in such an arrangement so as to support the weight of the rotor and provide it with

  18. Tardigrada (Water Bears)

    NSDL National Science Digital Library

    Micrographia

    This reference page offers a brief description of Tardigrades, also known as water bears. It includes information about their physical appearance, an explanation of their name, likely habitats, internal organs and other distinguishing features, and a few images. A diagram of a common tardigrade, Macrobiotus macronyx, is also provided via an internal link.

  19. Magnetic Bearings For Turbopumps

    NASA Technical Reports Server (NTRS)

    Meeks, Crawford R.; Mendez, Antonio J.

    1995-01-01

    Report presents study of feasibility of magnetic bearings in turbopumps. Liquid-oxygen turbopump in space shuttle main engine selected for study. Other potential applications include manned and unmanned spacecraft, gas turbines for commercial and military aircraft, turbomachinery for petro-chemical and gas operations, suspension systems for precise machinery, and precise pointing and tracking systems.

  20. Bear vs Bee

    NSDL National Science Digital Library

    2012-01-01

    This interactive Java applet is a game that challenges a student to solve problems by using logic and rudimentary engineering skills. The goal in each case is to create a conveyance that gets the bear to the pot of honey, avoiding the bees. The game has 32 stages of increasing complexity.

  1. Bearings Incorporating Deadband Rollers

    NASA Technical Reports Server (NTRS)

    Gualtieri, Guy V.

    1996-01-01

    Bearings in high-pressure turbopump redesigned to incorporate rollers allowing limited axial motion within small deadband. Does not permit radial deadband motion. Axial deadband motion used for rotor-thrust-balance control. Design eliminates some nonlinearities in dynamics of pump rotor and assists in suppressing vibrations at harmonics of frequency of rotation.

  2. History of ball bearings

    NASA Technical Reports Server (NTRS)

    Dowson, D.; Hamrock, B. J.

    1981-01-01

    The familiar precision rolling-element bearings of the twentieth century are products of exacting technology and sophisticated science. Their very effectiveness and basic simplicity of form may discourage further interest in their history and development. Yet the full story covers a large portion of recorded history and surprising evidence of an early recognition of the advantages of rolling motion over sliding action and progress toward the development of rolling-element bearings. The development of rolling-element bearings is followed from the earliest civilizations to the end of the eighteenth century. The influence of general technological developments, particularly those concerned with the movement of large building blocks, road transportation, instruments, water-raising equipment, and windmills are discussed, together with the emergence of studies of the nature of rolling friction and the impact of economic factors. By 1800 the essential features of ball and rolling-element bearings had emerged and it only remained for precision manufacture and mass production to confirm the value of these fascinating machine elements.

  3. Oregon Zoo Polar Bear

    USGS Multimedia Gallery

    Tasul, an Oregon Zoo polar bear, sports a high-tech collar that will help researchers study her endangered wild counterparts in the Arctic. Photo by Michael Durham, courtesy of the Oregon Zoo. Photo by Michael Durham, courtesy of the Oregon Zoo....

  4. Rolling bearing life models and steel internal cleanliness

    SciTech Connect

    Beswick, J.; Gabelli, A.; Ioannides, S.; Tripp, J.H.; Voskamp, A.P.

    1999-07-01

    The most widely used steel grade for rolling bearings is based on a steel composition first used almost a hundred years ago, the so-called 1C-1.5Cr steel. This steel is used either in a selective surface induction hardened conditions or in a through hardened heat treated condition, both yielding exceptional structural and contact fatigue properties. The Lundberg and Palmgren rolling bearing life prediction model, published in 1947, was the first analytical approach to bearing performance prediction, subsequently becoming a widely accepted basis for rolling bearing life calculations. At that time the fatigue life of rolling bearings was dominated by the classical sub-surface initiated failure mode. This mode results from the accumulation of micro-plastic strain at the depth of maximum Hertzian stress and is accelerated by the stress concentrations occurring at the micro internal defects. In common with all fatigue processes, rolling bearing failure is a statistical process: the failures of bearings with high inclusion content tested at high stress levels belong to the well-known family of Weibull distributions. Steady improvements in bearing steel cleanliness due, amongst other things, to the introduction of secondary metallurgy steel making techniques, have resulted in a significantly increased rolling bearing life and load carrying capacity. In recognition of this, in 1985 Ioannides and Harris introduced a new fatigue life model for rolling bearings, comprising a more widely applicable approach to the modeling of bearing life based on the relevant failure mode. Subsequently this has been extended to include effects of hardness and of micro-inclusion distributions in state-of-the-art clean bearing steel.

  5. The Great Bear Rainforest Spirit Bears, Grizzlies and Ancient Forests

    E-print Network

    de Leon, Alex R.

    The Great Bear Rainforest Spirit Bears, Grizzlies and Ancient Forests September 16 ­ 22, 2015 with Dr. Wayne Lynch The temperate rainforests are one of the richest habitats on Earth; supporting more at the movies and the Great Bear Rainforest is one of the world's best places to witness this primordial drama

  6. Vygotsky and the Three Bears

    ERIC Educational Resources Information Center

    Kulczewski, Peggy

    2004-01-01

    Peggy Kulczewski, a kindergarten classroom teacher, remembers the day when students enjoyed a story she told them from the book "The Three Bears". The students' discussion about comparison of the bears was very helpful to the whole group.

  7. A self-lubricating bearing

    NASA Technical Reports Server (NTRS)

    Whitaker, A. F. (inventor)

    1974-01-01

    An improved bearing structure is described which includes a permanently magnetized porous body filled with an interstitial magnetic lubricant for extending the operational life of self-lubricating bearings. The bearing structure is characterized by a permanently magnetized retainer formed of a porous material and filled with an interstitial magnetic lubricant, whereby the pores serve as lubricant reservoirs from which the lubricant continuously is delivered to a film disposed between contiguous bearing surfaces.

  8. Development of passive superconducting bearings. Phase 3. Final report

    SciTech Connect

    Rao, D.K.

    1993-05-14

    This report documents the work performed by MTI under contract to Strategic Defense Initiative Organization to develop the technology of Superconducting Bearings. This work, had been supported by NASA and DARPA in addition to SDIO. As a result of this work, MTI had developed a passive superconducting bearing that is used to levitate relatively heavy rotors. It used this bearing to levitate a 7 lb rotor and spin at speeds of up to 12,000 rpm. The success of this effort indicates that the superconducting bearings have potential for transition from a mere laboratory curiosity to a functional bearing component in a wider range of practical applications such as cryoturbopumps, miniature cryocoolers and magnetic refrigerators. In addition, MTI had investigated several configurations of using superconductors to support loads along a single axis. The effort was directed to identify a specific configuration that offers a very high stiffness.

  9. Carbon Nanotube Linear Bearing Nanoswitches

    E-print Network

    Bockrath, Marc

    Carbon Nanotube Linear Bearing Nanoswitches V. V. Deshpande, H.-Y. Chiu, H. W. Ch. Postma, C. Miko-friction bearing capabilities of multiwalled carbon nanotubes (MWNTs) to realize nanoelectromechanical switches bearing capabilities3-5 of multi- and double-walled carbon nanotubes (MWNTs and DWNTs) to realize

  10. Crystallization, dehydration and experimental phasing of WbdD, a bifunctional kinase and methyltransferase from Escherichia coli O9a

    SciTech Connect

    Hagelueken, Gregor; Huang, Hexian [The University of St Andrews, North Haugh, St Andrews KY16 9ST, Scotland (United Kingdom); Harlos, Karl [University of Oxford, Roosevelt Drive, Oxford OX3 7BN (United Kingdom); Clarke, Bradley R.; Whitfield, Chris [University of Guelph, Ontario N1G 2W1 (Canada); Naismith, James H., E-mail: naismith@st-and.ac.uk [The University of St Andrews, North Haugh, St Andrews KY16 9ST, Scotland (United Kingdom)

    2012-10-01

    The optimization of WbdD crystals using a novel dehydration protocol and experimental phasing at 3.5 Å resolution by cross-crystal averaging followed by molecular replacement of electron density into a non-isomorphous 3.0 Å resolution native data set are reported. WbdD is a bifunctional kinase/methyltransferase that is responsible for regulation of lipopolysaccharide O antigen polysaccharide chain length in Escherichia coli serotype O9a. Solving the crystal structure of this protein proved to be a challenge because the available crystals belonging to space group I23 only diffracted to low resolution (>95% of the crystals diffracted to resolution lower than 4 Å and most only to 8 Å) and were non-isomorphous, with changes in unit-cell dimensions of greater than 10%. Data from a serendipitously found single native crystal that diffracted to 3.0 Å resolution were non-isomorphous with a lower (3.5 Å) resolution selenomethionine data set. Here, a strategy for improving poor (3.5 Å resolution) initial phases by density modification and cross-crystal averaging with an additional 4.2 Å resolution data set to build a crude model of WbdD is desribed. Using this crude model as a mask to cut out the 3.5 Å resolution electron density yielded a successful molecular-replacement solution of the 3.0 Å resolution data set. The resulting map was used to build a complete model of WbdD. The hydration status of individual crystals appears to underpin the variable diffraction quality of WbdD crystals. After the initial structure had been solved, methods to control the hydration status of WbdD were developed and it was thus possible to routinely obtain high-resolution diffraction (to better than 2.5 Å resolution). This novel and facile crystal-dehydration protocol may be useful for similar challenging situations.

  11. Crystallization, dehydration and experimental phasing of WbdD, a bifunctional kinase and methyltransferase from Escherichia coli O9a

    PubMed Central

    Hagelueken, Gregor; Huang, Hexian; Harlos, Karl; Clarke, Bradley R.; Whitfield, Chris; Naismith, James H.

    2012-01-01

    WbdD is a bifunctional kinase/methyltransferase that is responsible for regulation of lipopolysaccharide O antigen polysaccharide chain length in Escherichia coli serotype O9a. Solving the crystal structure of this protein proved to be a challenge because the available crystals belonging to space group I23 only diffracted to low resolution (>95% of the crystals diffracted to resolution lower than 4?Å and most only to 8?Å) and were non-isomorphous, with changes in unit-cell dimensions of greater than 10%. Data from a serendipitously found single native crystal that diffracted to 3.0?Å resolution were non-isomorphous with a lower (3.5?Å) resolution selenomethionine data set. Here, a strategy for improving poor (3.5?Å resolution) initial phases by density modification and cross-crystal averaging with an additional 4.2?Å resolution data set to build a crude model of WbdD is desribed. Using this crude model as a mask to cut out the 3.5?Å resolution electron density yielded a successful molecular-replacement solution of the 3.0?Å resolution data set. The resulting map was used to build a complete model of WbdD. The hydration status of individual crystals appears to underpin the variable diffraction quality of WbdD crystals. After the initial structure had been solved, methods to control the hydration status of WbdD were developed and it was thus possible to routinely obtain high-resolution diffraction (to better than 2.5?Å resolution). This novel and facile crystal-dehydration protocol may be useful for similar challenging situations. PMID:22993091

  12. Bears in a Boat

    NSDL National Science Digital Library

    2012-06-14

    In this math activity, learners are challenged to create aluminum foil boats that will hold plastic bears until the boats sink. The lesson serves as a fun, hands-on way to collect data. Data from two attempts is collected and used to make two class box-and-whisker plots with some surprising results. This lesson guide includes questions for learners, assessment options, extensions, and reflection questions.

  13. The Polar Bear Game

    NSDL National Science Digital Library

    2010-10-24

    In this game, which is similar to Petals Around the Rose (cataloged separately), a player rolls 5 dice and asks the participants, “How many polar bears are around the ice holes?” The participants try to figure out the riddle (rules of the game) by studying the dice arrangements and the answers that correspond. This webpage extends the game to have players also determine the number of fish and plankton.

  14. Night of the Bear

    NSDL National Science Digital Library

    Casey Debenham

    2002-08-25

    The NOAA Ocean Exploration program strives to engage broad audiences to enhance America's environmental literacy through the excitement of ocean discovery. Increasing this literacy requires high-quality, effective collaborations between ocean explorers and America's teachers. NOAA is forming such collaborations to reach out in new ways to the public to improve the literacy of learners with respect to ocean issues. This site is a daily log of exploration in the Arctic and research on the Polar Bear.

  15. Grizzly bears and forestry

    Microsoft Academic Search

    Scott E. Nielsen; Mark S. Boyce; Gordon B. Stenhouse

    2004-01-01

    We examined if clearcuts were selected as habitats by grizzly bears (Ursus arctos L.) in west-central Alberta during three seasons: hypophagia, early hyperphagia, and late hyperphagia. Our objectives were to describe seasonal habitat selection of clearcuts using resource selection functions at two scales. At the first scale, we assessed patch or third-order selection by comparing use (radiotelemetry) with study area-wide

  16. Anti-backlash gear bearings

    NASA Technical Reports Server (NTRS)

    Vranish, John M. (Inventor)

    2009-01-01

    A gear bearing having a first gear and a second gear, each having a plurality of teeth. Each gear operates on two non-parallel surfaces of the opposing gear teeth to perform both gear and bearing functions simultaneously. The gears are moving at substantially the same speed at their contact points. The gears may be roller gear bearings or phase-shifted gear bearings, and may be arranged in a planet/sun system or used as a transmission. One preferred embodiment discloses and describes an anti-backlash feature to counter ''dead zones'' in the gear bearing movement.

  17. Bearing for liquid metal pump

    DOEpatents

    Dickinson, Robert J. (Shaler Township, Allegheny County, PA); Wasko, John (Plum Borough, PA); Pennell, William E. (Unity Township, Allegheny County, PA)

    1984-01-01

    A liquid metal pump bearing support comprises a series of tangentially oriented spokes that connect the bearing cylinder to the pump internals structure. The spokes may be arranged in a plurality of planes extending from the bearing cylinder to the pump internals with the spokes in one plane being arranged alternately with those in the next plane. The bearing support structure provides the pump with sufficient lateral support for the bearing structure together with the capability of accommodating differential thermal expansion without adversely affecting pump performance.

  18. Hybrid hydrostatic/ball bearings in high-speed turbomachinery

    NASA Technical Reports Server (NTRS)

    Nielson, C. E.

    1983-01-01

    A high speed, high pressure liquid hydrogen turbopump was designed, fabricated, and tested under a previous contract. This design was then modified to incorporate hybrid hydrostatic/ball bearings on both the pump end and turbine end to replace the original conventional ball bearing packages. The design, analysis, turbopump modification, assembly, and testing of the turbopump with hybrid bearings is presented here. Initial design considerations and rotordynamic performance analysis was made to define expected turbopump operating characteristics and are reported. The results of testing the turbopump to speeds of 9215 rad/s (88,000 rpm) using a wide range of hydrostatic bearing supply pressures are presented. The hydrostatic bearing test data and the rotordynamic behavior of the turbopump was closely analyzed and are included in the report. The testing of hybrid hydrostatic/ball bearings on a turbopump to the high speed requirements has indicated the configuration concept is feasible. The program has presented a great deal of information on the technology requirements of integrating the hybrid bearing into high speed turbopump designs for improved bearing life.

  19. Performance of an active electric bearing for rotary micromotors

    NASA Astrophysics Data System (ADS)

    Han, F. T.; Wang, L.; Wu, Q. P.; Liu, Y. F.

    2011-08-01

    An electric bearing used to support a micromachined rotor of variable-capacitance motors was designed and tested in order to study the characteristics of this frictionless bearing. Electrostatic suspension of a ring-shaped rotor in five degrees of freedom is required to eliminate the mechanical bearing and thus the friction and wear between the rotor and the substrate. Bulk microfabrication-based glass/silicon/glass bonding is chosen for this device, allowing the fabrication of large area sense capacitors and rotor, which make the device potentially suitable for the development of an electrostatically suspended micromachined gyroscope. The device and its basic operating principle are described, as well as the dynamics of the rotor and basic design considerations of the electric bearing system. A theoretical relationship to relate the characteristics of a classical lag-lead compensator to the stiffness properties of the electric bearing is developed to explain the experimental bearing measurements. The experimental results of closed-loop frequency response, suspension stiffness and drive voltage effects are presented and discussed for the bearing operated initially in the atmospheric environment. The performance of a tri-axial electrostatic accelerometer has also been experimentally investigated on the prototype of the electric bearing system.

  20. Kalman Filter Behavior in Bearings-Only Tracking Applications

    Microsoft Academic Search

    Vincent Aidala

    1979-01-01

    The extended Kalman filter applied to bearings-only target tracking is theoretically analyzed. Closed-form expressions for the state vector and its associated covariance matrix are introduced, and subsequently used to demonstrate how bearing and range estimation errors can interact to cause filter instability (i.e., premature covariance collapse and divergence). Further investigation reveals that conventional initialization techniques often precipitate such anomalous behavior.

  1. Bearing construction for refrigeration compresssor

    DOEpatents

    Middleton, Marc G. (Wyoming, MI); Nelson, Richard T. (Worthington, OH)

    1988-01-01

    A hermetic refrigeration compressor has a cylinder block and a crankshaft rotatable about a vertical axis to reciprocate a piston in a cylinder on the cylinder block. A separate bearing housing is secured to the central portion of the cylinder block and extends vertically along the crankshaft, where it carries a pair of roller bearings to journal the crankshaft. The crankshaft has a radially extending flange which is journaled by a thrust-type roller bearing above the bearing housing to absorb the vertical forces on the crankshaft so that all three of the roller bearings are between the crankshaft and the bearing housing to maintain and control the close tolerances required by such bearings.

  2. Effect of Bearing Cleaning on Long Term Bearing Life

    NASA Technical Reports Server (NTRS)

    Jett, Tim; Thom, R. L.

    1999-01-01

    For many years chlorofluorocarbon (CFC) based solvents, such as CFC-113 and 1,1,1, trichloroethane (TCA), were used as bearing cleaning solvents for space mechanism bearings. The 1995 ban on the production of ozone depleting chemicals (ODC) such as CFCs caused a change requiring the use of ODC-free cleaners for precision bearing cleaning. With this change the question arises; what effect if any do these new cleaners have on long term bearing life? The purpose of this study was to evaluate this effect. A one year test using 60 small electrical motors (two bearings per motor) was conducted in a high vacuum environment (2.0 x 10(exp -6) torr) at a temperature of 90 C. Prior to testing the bearings were cleaned with one of four cleaners. These cleaners included two aqueous based cleaners, a CFC based cleaner and supercritical carbon dioxide. Three space compatible greases were tested. After testing, the mass of each lubricated bearing was measured both pre and post test. Along with mass loss measurements a profilometer trace of each bearing was taken to measure post test wear of the bearings. In addition, the bearings were visually examined and analyzed using an optical microscope.

  3. Efficacy of Bear Deterrent Spray in Alaska

    Microsoft Academic Search

    Tom S. Smith; Stephen Herrero; Terry D. Debruyn; James M. Wilder

    2008-01-01

    We present a comprehensive look at a sample of bear spray incidents that occurred in Alaska, USA, from 1985 to 2006. We analyzed 83 bear spray incidents involving brown bears (Ursus arctos; 61 cases, 74%), black bears (Ursus americanus; 20 cases, 24%), and polar bears (Ursus maritimus; 2 cases, 2%). Of the 72 cases where persons sprayed bears to defend

  4. Conservation of brown bear in the Alps: space use and settlement behavior of reintroduced bears

    NASA Astrophysics Data System (ADS)

    Preatoni, Damiano; Mustoni, Andrea; Martinoli, Adriano; Carlini, Eugenio; Chiarenzi, Barbara; Chiozzini, Simonetta; Van Dongen, Stefan; Wauters, Luc A.; Tosi, Guido

    2005-11-01

    Large carnivores typically need large home ranges containing habitats patches of different quality. Consequently, their conservation requires habitat protection and management at the landscape scale. In some cases, reintroduction might be used to support remnant or restore extinct populations. This is the case for the brown bear ( Ursus arctos) in the Italian Alps. We monitored spacing behavior and settlement of reintroduced brown bears in Adamello-Brenta Natural Park, North-Italy, using radio-tracking. Habitat use, dispersion and survival were studied to evaluate the success of reintroduction and possible conflicts with man. All three males and five of seven females settled in the study area. Most bears roamed widely the first months after release, exploring the new habitat. Patterns of home range overlap between seasons and years revealed that home range use stabilized the year after first hibernation. Home ranges were larger in the mating season (May-July) than in spring or autumn. Home ranges varied between 34 and 1813 km 2 the year after release, but core-areas, where feeding activity was concentrated, were much smaller. Some bears had exclusive core-areas in summer and autumn, but most showed considerable core-area overlap with animals of the same and/or the opposite sex. Bears selected deciduous forests, mixed and conifer forests were used according to availability, and areas with anthropogenic disturbance were avoided. Most bears settled and some reproduced successfully at the release site, causing high initial population growth, suggesting that reintroduction can help to re-establish a brown bear population in the Italian Alps.

  5. High-Speed Shaft Bearing Loads Testing and Modeling in the NREL Gearbox Reliability Collaborative: Preprint

    SciTech Connect

    McNiff, B.; Guo, Y.; Keller, J.; Sethuraman, L.

    2014-12-01

    Bearing failures in the high speed output stage of the gearbox are plaguing the wind turbine industry. Accordingly, the National Renewable Energy Laboratory (NREL) Gearbox Reliability Collaborative (GRC) has performed an experimental and theoretical investigation of loads within these bearings. The purpose of this paper is to describe the instrumentation, calibrations, data post-processing and initial results from this testing and modeling effort. Measured HSS torque, bending, and bearing loads are related to model predictions. Of additional interest is examining if the shaft measurements can be simply related to bearing load measurements, eliminating the need for invasive modifications of the bearing races for such instrumentation.

  6. Dialogue for Kids Wild About Bears Sleepy Bear Lesson Plan

    NSDL National Science Digital Library

    Each winter, bears hunker down, slow their metabolisms, and pretty much wait out the winter in the safety of some sort of den. This lesson plan, from Idaho Public Television, is a fun way to illustrate to children (probably elementary grades primarily) the process of hibernation. At this site, educators are given the complete lesson plan instructions as well as several links to all sorts of great resources, including links to information on: Bear Diet, Home Range, Reproduction, Bear Research, People and Bears, more Classroom Activities, and more. And, the great addition to the site is a link to a 30-minute video about bears. While the site is somewhat focused on Idaho-specific bear information, teachers should be able to easily integrate the lesson no matter where you are.

  7. Aerospace applications of magnetic bearings

    NASA Technical Reports Server (NTRS)

    Downer, James; Goldie, James; Gondhalekar, Vijay; Hockney, Richard

    1994-01-01

    Magnetic bearings have traditionally been considered for use in aerospace applications only where performance advantages have been the primary, if not only, consideration. Conventional wisdom has been that magnetic bearings have certain performance advantages which must be traded off against increased weight, volume, electric power consumption, and system complexity. These perceptions have hampered the use of magnetic bearings in many aerospace applications because weight, volume, and power are almost always primary considerations. This paper will review progress on several active aerospace magnetic bearings programs at SatCon Technology Corporation. The magnetic bearing programs at SatCon cover a broad spectrum of applications including: a magnetically-suspended spacecraft integrated power and attitude control system (IPACS), a magnetically-suspended momentum wheel, magnetic bearings for the gas generator rotor of a turboshaft engine, a vibration-attenuating magnetic bearing system for an airborne telescope, and magnetic bearings for the compressor of a space-rated heat pump system. The emphasis of these programs is to develop magnetic bearing technologies to the point where magnetic bearings can be truly useful, reliable, and well tested components for the aerospace community.

  8. Cobalt nanoparticles embedded in N-doped carbon as an efficient bifunctional electrocatalyst for oxygen reduction and evolution reactions

    NASA Astrophysics Data System (ADS)

    Su, Yunhe; Zhu, Yihua; Jiang, Hongliang; Shen, Jianhua; Yang, Xiaoling; Zou, Wenjian; Chen, Jianding; Li, Chunzhong

    2014-11-01

    Cobalt based catalysts are promising bifunctional electrocatalysts for both oxygen reduction and oxygen evolution reactions (ORR and OER) in unitized regenerative fuel cells (URFCs) operating with alkaline electrolytes. Here we report a hybrid composite of cobalt nanoparticles embedded in nitrogen-doped carbon (Co/N-C) via a solvothermal carbonization strategy. With the synergistic effect arising from the N-doped carbon and cobalt nanoparticles in the composite, the Co/N-C hybrid catalyst exhibits highly efficient bifunctional catalytic activity and excellent stability toward both ORR and OER. The ?E (oxygen electrode activity parameter for judging the overall electrocatalytic activity of a bifunctional electrocatalyst) value for Co/N-C is 0.859 V, which is smaller than those of Pt/C and most of the non-precious metal catalysts in previous studies. Furthermore, the Co/N-C composite also shows better bifunctional catalytic activity than its oxidative counterparts, which could be attributed to the high specific surface area and the efficient charge transfer ability of the composite, as well as the good synergistic effect between N-doped carbon and the Co nanoparticles in the Co/N-C composite.Cobalt based catalysts are promising bifunctional electrocatalysts for both oxygen reduction and oxygen evolution reactions (ORR and OER) in unitized regenerative fuel cells (URFCs) operating with alkaline electrolytes. Here we report a hybrid composite of cobalt nanoparticles embedded in nitrogen-doped carbon (Co/N-C) via a solvothermal carbonization strategy. With the synergistic effect arising from the N-doped carbon and cobalt nanoparticles in the composite, the Co/N-C hybrid catalyst exhibits highly efficient bifunctional catalytic activity and excellent stability toward both ORR and OER. The ?E (oxygen electrode activity parameter for judging the overall electrocatalytic activity of a bifunctional electrocatalyst) value for Co/N-C is 0.859 V, which is smaller than those of Pt/C and most of the non-precious metal catalysts in previous studies. Furthermore, the Co/N-C composite also shows better bifunctional catalytic activity than its oxidative counterparts, which could be attributed to the high specific surface area and the efficient charge transfer ability of the composite, as well as the good synergistic effect between N-doped carbon and the Co nanoparticles in the Co/N-C composite. Electronic supplementary information (ESI) available: Detailed and additional figures as noted in the text. See DOI: 10.1039/c4nr04357j

  9. Novel 3-nitrotriazole-based amides and carbinols as bifunctional antichagasic agents.

    PubMed

    Papadopoulou, Maria V; Bloomer, William D; Lepesheva, Galina I; Rosenzweig, Howard S; Kaiser, Marcel; Aguilera-Venegas, Benjamín; Wilkinson, Shane R; Chatelain, Eric; Ioset, Jean-Robert

    2015-02-12

    3-Nitro-1H-1,2,4-triazole-based amides with a linear, rigid core and 3-nitrotriazole-based fluconazole analogues were synthesized as dual functioning antitrypanosomal agents. Such compounds are excellent substrates for type I nitroreductase (NTR) located in the mitochondrion of trypanosomatids and, at the same time, act as inhibitors of the sterol 14?-demethylase (T. cruzi CYP51) enzyme. Because combination treatments against parasites are often superior to monotherapy, we believe that this emerging class of bifunctional compounds may introduce a new generation of antitrypanosomal drugs. In the present work, the synthesis and in vitro and in vivo evaluation of such compounds is discussed. PMID:25580906

  10. A novel bifunctional maleimido CHX-A'' chelator for conjugation to thiol-containing biomolecules.

    PubMed

    Xu, Heng; Baidoo, Kwamena E; Wong, Karen J; Brechbiel, Martin W

    2008-04-15

    A novel bifunctional maleimido CHX-A'' DTPA chelator 5 was developed and conjugated to the monoclonal antibody trastuzumab (Herceptin) and subsequently radiolabeled with (111)In. The resulting (111)In labeled immunoconjugate 2 was demonstrated to bind to SKOV-3 ovarian cancer cells comparably to an isothiocyanato CHX-A'' DTPA modified native trastuzumab, 1. Through efficient thiol-maleimide chemistry, antibodies, peptides or other targeting vectors can now be modified with an established radioactive metal chelating agent CHX-A'' DTPA for imaging and/or therapies of cancer. PMID:18359632

  11. Crystal structure of the invertebrate bifunctional purine biosynthesis enzyme PAICS at 2.8 Å resolution.

    PubMed

    Taschner, Michael; Basquin, Jérôme; Benda, Christian; Lorentzen, Esben

    2013-08-01

    Two important steps of the de novo purine biosynthesis pathway are catalyzed by the 5-aminoimidazole ribonucleotide carboxylase and the 4-(N-succinylcarboxamide)-5-aminoimidazole ribonucleotide synthetase enzymes. In most eukaryotic organisms, these two activities are present in the bifunctional enzyme complex known as PAICS. We have determined the 2.8-Å resolution crystal structure of the 350-kDa invertebrate PAICS from insect cells (Trichoplusia ni) using single-wavelength anomalous dispersion methods. Comparison of insect PAICS to human and prokaryotic homologs provides insights into substrate binding and reveals a highly conserved enzymatic framework across divergent species. PMID:23553965

  12. Contrast-Enhanced MRI-Guided Photodynamic Cancer Therapy with a Pegylated Bifunctional Polymer Conjugate

    Microsoft Academic Search

    Anagha Vaidya; Yongen Sun; Yi Feng; Lyska Emerson; Eun-Kee Jeong; Zheng-Rong Lu

    2008-01-01

    Purpose  To study contrast-enhanced MRI guided photodynamic therapy with a pegylated bifunctional polymer conjugate containing an MRI\\u000a contrast agent and a photosensitizer for minimally invasive image-guided cancer treatment.\\u000a \\u000a \\u000a \\u000a Methods  Pegylated and non-pegylated poly-(l-glutamic acid) conjugates containing mesochlorin e6, a photosensitizer, and Gd(III)-DO3A, an MRI contrast agent, were synthesized. The effect of pegylation on the biodistribution\\u000a and tumor targeting was non-invasively visualized in

  13. Preparation of bifunctional isocyanate hydroxamate linkers: Synthesis of carbamate and urea tethered polyhydroxamic acid chelators.

    PubMed

    Fernando, Rasika; Shirley, Jonathan M; Torres, Emilio; Jacobs, Hollie K; Gopalan, Aravamudan S

    2012-11-21

    Two novel bifunctional N-methylhydroxamate-isocyanate linkers 20 and 21 were prepared in good yield and high purity from the corresponding amine salts using a biphasic reaction with phosgene. The facile ring opening reaction of N-Boc lactams using the anion of O-benzylhydroxylamine gave the protected amino hydroxamates 6a and 6c in good yields. The selective methylation of the hydroxamate nitrogen in the presence of the N-Boc group in these intermediates could be readily accomplished. The utility of the linkers was clearly demonstrated by the synthesis of the carbamate-tethered trishydroxamic acid 27 and the urea-tethered 29. PMID:23162172

  14. Effect of Bearing Cleaning on Long Term Bearing Life

    NASA Technical Reports Server (NTRS)

    Jett, Timothy Raymond; Thom, Robert L.

    1998-01-01

    For many years chlorofluorocarbon (CFC ) based solvents, such as Freon and 1,1,1, Trichloroethane (TCA), were used as bearing cleaning solvents for space mechanisms. The 1995 ban on the production of ozone depleting chemicals (ODC) such as CFCs caused a change to new ODC-free cleaners for the precision bearing cleaning. With this change the question arises what effect if any do these new cleaners have on long term bearing life. The purpose of this study was to evaluate this effect. A one year test using 60 small electrical motors (two bearings per motor) was conducted in a high vacuum environment (2.0* 10(exp -6) torr) at a temperature of 90C. Prior to testing the bearings were cleaned with one of four cleaners. These cleaners included two aqueous based cleaners, a CFC based cleaner and supercritical carbon dioxide. Three space compatible greases were tested. After testing the mass of each lubricated bearing was measured both pre and post test. Along with mass loss measurements a profilometer trace of each bearing was taken to measure post test wear of the bearings. In addition the bearings were visually examined and analyzed using an optical microscope.

  15. The effect of ion implantation on the fatigue life and corrosion resistance of M50 steel bearings

    Microsoft Academic Search

    A. Dodd; J. Kinder; B. Torp; B. R. Nielsen; C. M. Rangel; M. F. da Silva

    1995-01-01

    With the overall objective to improve the service life and reliability of gas turbine engine bearings by increasing their corrosion resistance, a collaborative project under the EEC BRITE\\/EURAM programme was initiated. The project was aimed at developing an ion implantation technique to implant bearing components with metallic species and to optimize the process to improve the service life of bearings

  16. Ball bearing heat analysis program (BABHAP)

    NASA Technical Reports Server (NTRS)

    1978-01-01

    The Ball Bearing Heat Analysis Program (BABHAP) is an attempt to assemble a series of equations, some of which are non-linear algebraic systems, in a logical order, which when solved, provide a complex analysis of load distribution among the balls, ball velocities, heat generation resulting from friction, applied load, and ball spinning, minimum lubricant film thickness, and many additional characteristics of ball bearing systems. Although initial design requirements for BABHAP were dictated by the core limitations of the PDP 11/45 computer, (approximately 8K of real words with limited number of instructions) the program dimensions can easily be expanded for large core computers such as the UNIVAC 1108. The PDP version of BABHAP is also operational on the UNIVAC system with the exception that the PDP uses 029 punch and the UNIVAC uses 026. A conversion program was written to allow transfer between machines.

  17. Totally frictionless magnetic bearing

    NASA Astrophysics Data System (ADS)

    Dodakian, Wayne; Bulman, John

    2000-11-01

    A totally frictionless magnetic bearing has been developed which supports a rotor in a contactless manner. The rotor is held in a magnetic potential well via repulsive forces only. Vertical and lateral restoring forces are provided to the rotor passively via permanent magnets in such an arrangement so as to support the weight of the rotor and provide it with a high degree of lateral stability. Axial stability of the rotor is provided by the use of an electromagnet which is controlled by a PID control loop. Information on the axial position of the rotor is provided to the circuit by use of an infrared LED and IR phototransistor. To prevent unwanted oscillations of the rotor’s axial position from occurring, an oscillation sensor in the form of an inductive pick-up coil of high impedance provides signals to the oscillation sensing portion of the circuit, which in turn feeds the oscillation dampening circuit. The use of only repulsive forces in stabilizing the rotor means that there will be no eddy current losses or hysterisis losses. Such a frictionless magnetic bearing can, for example be used in rotational oscillation experiments and ultra low loss watt-hour meters, which are of great importance to utility companies. When properly tuned, the total power requirements of the circuit is a mere 40mW, which is less than the 80 mW used by present day watt-hour meters.

  18. Robust and intelligent bearing estimation

    DOEpatents

    Claassen, John P. (Albuquerque, NM)

    2000-01-01

    A method of bearing estimation comprising quadrature digital filtering of event observations, constructing a plurality of observation matrices each centered on a time-frequency interval, determining for each observation matrix a parameter such as degree of polarization, linearity of particle motion, degree of dyadicy, or signal-to-noise ratio, choosing observation matrices most likely to produce a set of best available bearing estimates, and estimating a bearing for each observation matrix of the chosen set.

  19. Primarily Pro-bear-bility

    NSDL National Science Digital Library

    2006-01-01

    In this probability lesson plan students make predictions about the color of the bear they are likely to draw from a bag, and then draw and record the color of the bear they actually draw. Students complete this activity in cooperative learning groups and take turns removing a bear, without replacing it, and seeing if their predictions become more accurate. The lesson plan includes four student activity worksheets and extension questions and suggestions (PDF).

  20. Spin bearing retainer design optimization

    NASA Technical Reports Server (NTRS)

    Boesiger, Edward A.; Warner, Mark H.

    1991-01-01

    The dynamics behavior of spin bearings for momentum wheels (control-moment gyroscope, reaction wheel assembly) is critical to satellite stability and life. Repeated bearing retainer instabilities hasten lubricant deterioration and can lead to premature bearing failure and/or unacceptable vibration. These instabilities are typically distinguished by increases in torque, temperature, audible noise, and vibration induced by increases into the bearing cartridge. Ball retainer design can be optimized to minimize these occurrences. A retainer was designed using a previously successful smaller retainer as an example. Analytical methods were then employed to predict its behavior and optimize its configuration.

  1. Toxic Chemicals Initiative

    NSDL National Science Digital Library

    This World Wildlife Fund initiative is aimed at banning the most deadly, persistent pollutants (such as DDT, PCBs, and dioxins) that endanger every species, ecosystem, and community on Earth. The serious damage to the health of wildlife and humans caused by synthetic chemical contamination is addressed. There are documents about persistent organic pollutants, and endocrine disrupting chemicals. There are also several photographs of polar bears and other animals.

  2. Pushing the Theoretical Limit of Li-CFx Batteries: A Tale of Bi-functional Electrolyte

    SciTech Connect

    Rangasamy, Ezhiylmurugan [ORNL] [ORNL; Li, Juchuan [ORNL] [ORNL; Sahu, Gayatri [ORNL] [ORNL; Dudney, Nancy J [ORNL] [ORNL; Liang, Chengdu [ORNL] [ORNL

    2014-01-01

    In a typical battery, electrodes deliver capacities less or equal the theoretical maxima of the electrode materials.1 The inert electrolyte functions solely as the ionic conductor without contribution to the cell capacity because of its distinct mono-function in the concept of conventional batteries. Here we demonstrate that the most energy-dense Li-CFx battery2 delivers a capacity exceeding the theoretical maximum of CFx with a solid electrolyte of Li3PS4 (LPS) that has dual functions: as the inert electrolyte at the anode and the active component at the cathode. Such a bi-functional electrolyte reconciles both inert and active characteristics through a synergistic discharge mechanism of CFx and LPS. Li3PS4 is known as an inactive solid electrolyte with a broad electrochemical window over 5 V.3 The synergy at the cathode is through LiF, the discharge product of CFx, which activates the electrochemical discharge of LPS at a close electrochemical potential of CFx. Therefore, the solid-state Li-CFx batteries output 126.6% energy beyond their theoretic limits without compromising the stability of the cell voltage. The extra energy comes from the electrochemical discharge of LPS, the inert electrolyte. This bi-functional electrolyte revolutionizes the concept of conventional batteries and opens a new avenue for the design of batteries with an unprecedentedly high energy density.

  3. Carbon Nitrogen Nanotubes as Efficient Bifunctional Electrocatalysts for Oxygen Reduction and Evolution Reactions.

    PubMed

    Yadav, Ram Manohar; Wu, Jingjie; Kochandra, Raji; Ma, Lulu; Tiwary, Chandra Sekhar; Ge, Liehui; Ye, Gonglan; Vajtai, Robert; Lou, Jun; Ajayan, Pulickel M

    2015-06-10

    Oxygen reduction and evolution reactions are essential for broad range of renewable energy technologies such as fuel cells, metal-air batteries and hydrogen production through water splitting, therefore, tremendous effort has been taken to develop excellent catalysts for these reactions. However, the development of cost-effective and efficient bifunctional catalysts for both reactions still remained a grand challenge. Herein, we report the electrocatalytic investigations of bamboo-shaped carbon nitrogen nanotubes (CNNTs) having different diameter distribution synthesized by liquid chemical vapor deposition technique using different nitrogen containing precursors. These CNNTs are found to be efficient bifunctional electrocatalyst for oxygen reduction and evolution reactions. The electrocatalytic activity strongly depends on the nanotube diameter as well as nitrogen functionality type. The higher diameter CNNTs are more favorable for these reactions. The increase in nanotube diameter itself enhances the catalytic activity by lowering the oxygen adsorption energy, better conductivity, and further facilitates the reaction by increasing the percentage of catalytically active nitrogen moieties in CNNTs. PMID:25970133

  4. Facile synthesis of folate-conjugated magnetic/fluorescent bifunctional microspheres

    PubMed Central

    2014-01-01

    In this paper, we investigated the functional imaging properties of magnetic microspheres composed of magnetic core and CdTe quantum dots in the silica shell functionalized with folic acid (FA). The preparation procedure included the preparation of chitosan-coated Fe3O4 nanoparticles (CS-coated Fe3O4 NPs) prepared by a one-pot solvothermal method, the reaction between carboxylic and amino groups under activation of NHS and EDC in order to obtain the CdTe-CS-coated Fe3O4 NPs, and finally the growth of SiO2 shell vent the photoluminescence (PL) quenching via a Stöber method (Fe3O4-CdTe@SiO2). Moreover, in order to have a specific targeting capacity, the magnetic and fluorescent bifunctional microspheres were synthesized by bonding of SiO2 shell with FA molecules via amide reaction (Fe3O4-CdTe@SiO2-FA). The morphology, size, chemical components, and magnetic property of as-prepared composite nanoparticles were characterized by ultraviolet-visible spectroscopy, fluorescent spectroscopy, Fourier transform infrared spectroscopy (FTIR), X-ray powder diffraction (XRD), scanning transmission electron microscopy (SEM), transmission electron microscopy (TEM), thermogravimetric analysis (TGA), and vibrating sample magnetometer (VSM), respectively. The results show that the magnetic and fluorescent bifunctional microspheres have strong luminescent which will be employed for immuno-labeling and fluorescent imaging of HeLa cells. PMID:25328504

  5. Modeling Chemotaxis Reveals the Role of Reversed Phosphotransfer and a Bi-Functional Kinase-Phosphatase

    PubMed Central

    Maini, Philip K.; Armitage, Judith P.

    2010-01-01

    Understanding how multiple signals are integrated in living cells to produce a balanced response is a major challenge in biology. Two-component signal transduction pathways, such as bacterial chemotaxis, comprise histidine protein kinases (HPKs) and response regulators (RRs). These are used to sense and respond to changes in the environment. Rhodobacter sphaeroides has a complex chemosensory network with two signaling clusters, each containing a HPK, CheA. Here we demonstrate, using a mathematical model, how the outputs of the two signaling clusters may be integrated. We use our mathematical model supported by experimental data to predict that: (1) the main RR controlling flagellar rotation, CheY6, aided by its specific phosphatase, the bifunctional kinase CheA3, acts as a phosphate sink for the other RRs; and (2) a phosphorelay pathway involving CheB2 connects the cytoplasmic cluster kinase CheA3 with the polar localised kinase CheA2, and allows CheA3-P to phosphorylate non-cognate chemotaxis RRs. These two mechanisms enable the bifunctional kinase/phosphatase activity of CheA3 to integrate and tune the sensory output of each signaling cluster to produce a balanced response. The signal integration mechanisms identified here may be widely used by other bacteria, since like R. sphaeroides, over 50% of chemotactic bacteria have multiple cheA homologues and need to integrate signals from different sources. PMID:20808885

  6. Construction of a bifunctional enzyme fusion for the combined determination of biogenic amines in foods.

    PubMed

    Lee, Jae-Ick; Jang, Jun-Hyuck; Yu, Mi-Ji; Kim, Young-Wan

    2013-09-25

    Biogenic amines (BAs) are a group of low-molecular-mass organic bases derived from free amino acids. Due to the undesirable effects of BAs on human health, amine oxidase-based detection methods for BAs in foods have been developed. Here, we developed a bifunctional enzyme fusion (MAPO) using a Cu(2+)-containing monoamine oxidase (AMAO2) and a flavin adenine dinucleotide-containing putrescine oxidase (APUO) from Arthrobacter aurescens. It was necessary to activate MAPO with supplementary Cu(2+) ions, leading to a 6- to 12-fold improvement in catalytic efficiency (kcat/KM) for monoamines. The optimal temperatures of Cu(2+)-activated MAPO (cMAPO) for both tyramine and putrescine were 50 °C, and the optimal pH values for tyramine and putrescine were pH 7.0 and pH 8.0, respectively, consistent with those of AMAO2 and APUO, respectively. The cMAPO showed relative specific activities of 100, 99, 32, and 32 for 2-phenylethylamine, tyramine, histamine, and putrescine, respectively. The tyramine-equivalent BA contents of fermented soybean pastes by cMAPO were more than 90% of the total BA determined by HPLC. In conclusion, cMAPO is fully bifunctional toward biogenic monoamines and putrescine, allowing the combined determination of multiple BAs in foods. This colorimetric determination method could be useful for point-of-care testing to screen safety-guaranteed products prior to instrumental analyses. PMID:24001036

  7. Structure and regulation of the bifunctional enzyme lysine-oxoglutarate reductase-saccharopine dehydrogenase in maize.

    PubMed

    Kemper, E L; Cord-Neto, G; Capella, A N; Gonçalves-Butruile, M; Azevedo, R A; Arruda, P

    1998-05-01

    The lysine-oxoglutarate reductase (LOR) domain of the bifunctional enzyme lysine-oxoglutarate reductase-saccharopine dehydrogenase (LOR/SDH) from maize endosperm was shown to be activated by Ca2+, high salt concentration, organic solvents and Mg2+. The Ca2+-dependent enhancement of LOR activity was inhibited by the calmodulin antagonists N-(6-aminohexyl)-5-chloro-1-naphthalenesulfonamide (W7) and calmidazolium. Limited proteolysis was used to assess the structure/function relationship of the enzyme. Digestion with elastase separated the bifunctional 125-kDa polypeptide into two polypeptides of 65 kDa and 57 kDa, containing the functional domains of LOR and SDH, respectively. Proteolysis did not affect SDH activity, while LOR showed a time-dependent and protease-concentration-dependent inactivation followed by reactivation. Prolonged digestion or increasing amounts of elastase produced a complex pattern of limit polypeptides derived from additional cleavage sites within the 65-kDa (LOR) and 57-kDa (SDH) domains. The SDH-containing polypeptides inhibited the enzymatic activity of LOR-containing polypeptides. When separated from the SDH domain by limited proteolysis and ion-exchange chromatography, the LOR domain retained its Ca2+ activation property, but was no longer activated by high salt concentrations. These results suggest that the LOR activity of the native enzyme is normally inhibited such that after modulation, the enzyme undergoes a conformational alteration to expose the catalytic domain for substrate binding. PMID:9654071

  8. Sulfonic and phosphonic acid and bifunctional organic-inorganic hybrid membranes and their proton conduction properties.

    PubMed

    Sel, Ozlem; Azais, Thierry; Maréchal, Manuel; Gébel, Gérard; Laberty-Robert, Christel; Sanchez, Clément

    2011-11-01

    Hybrid organic-inorganic approaches are used for the synthesis of bifunctional proton exchange membrane fuel cell (PEMFC) membranes owing to their ability to combine the properties of a functionalized inorganic network and an organic thermostable polymer. We report the synthesis of both sulfonic and phosphonic acid functionalized mesostructured silica networks into a poly(vinylidenefluoride-co-hexafluoropropylene) (poly(VDF-co-HFP) copolymer. These membranes, containing different amounts of phosphonic acid and sulfonic acid groups, have been characterized using FTIR and NMR spectroscopy, SA-XRD, SAXS, and electrochemical techniques. The proton conductivity of the bifunctional hybrid membranes depends strongly on hydration, increasing by two orders of magnitude over the relative humidity (RH) range of 20 to 100%, up to a maximum of 0.031 S cm(-1) at 60 °C and 100% RH. This value is interesting as only half of the membrane conducts protons. This approach allows the synthesis of a porous SiO(2) network with two different functions, having -SO(3)H and -PO(3)H(2) embedded in a thermostable polymer matrix. PMID:21850711

  9. Peroxisomal D-bifunctional protein deficiency: First case reports from Slovakia.

    PubMed

    Konko?ová, J; Petrovi?, R; Chandoga, J; Repiský, M; Zelinková, H; Kršiaková, J; Kolníková, M; Kantarská, D; Šutovský, S; Böhmer, D

    2015-08-15

    D-bifunctional protein deficiency (#OMIM 261515) is a rare autosomal recessive hereditary metabolic disorder causing severe clinical and biochemical abnormalities that are usually fatal in the course of the first years of life. This disease is classified as single enzyme peroxisomal disorder affecting the ?-oxidation pathway in this compartment. In this paper we present a full overview of the clinical presentation, magnetic resonance imaging, biochemical and molecular data of two Slovak D-bifunctional protein deficient patients. In the clinical presentation of both patients severe generalized hypotonia, depression of neonatal reflexes, craniofacial dysmorphism and seizures dominated starting from the second day of life. In both patients, who died up to two years of life, we found elevated plasma levels of very long chain fatty acids and we identified the presence of causative mutations in the HSD17B4 gene. In the first case, we found the homozygous mutation c.46G>A, which is responsible for a defect in the dehydrogenase domain. In the second patient, the heterozygous mutations c.1369A>G and c.1516C>T were present and functionally they are related to the hydratase domain of the protein. This combination of mutations in the second patient is very rare and has not been reported until now. The presence of mutations was examined in all family members, and the resulting data were successfully utilized for prenatal diagnosis. PMID:25967389

  10. The Bifunctional Pyruvate Decarboxylase/Pyruvate Ferredoxin Oxidoreductase from Thermococcus guaymasensis

    PubMed Central

    2014-01-01

    The hyperthermophilic archaeon Thermococcus guaymasensis produces ethanol as a metabolic end product, and an alcohol dehydrogenase (ADH) catalyzing the reduction of acetaldehyde to ethanol has been purified and characterized. However, the enzyme catalyzing the formation of acetaldehyde has not been identified. In this study an enzyme catalyzing the production of acetaldehyde from pyruvate was purified and characterized from T. guaymasensis under strictly anaerobic conditions. The enzyme had both pyruvate decarboxylase (PDC) and pyruvate ferredoxin oxidoreductase (POR) activities. It was oxygen sensitive, and the optimal temperatures were 85°C and >95°C for the PDC and POR activities, respectively. The purified enzyme had activities of 3.8 ± 0.22?U?mg?1 and 20.2 ± 1.8?U?mg?1, with optimal pH-values of 9.5 and 8.4 for each activity, respectively. Coenzyme A was essential for both activities, although it did not serve as a substrate for the former. Enzyme kinetic parameters were determined separately for each activity. The purified enzyme was a heterotetramer. The sequences of the genes encoding the subunits of the bifunctional PDC/POR were determined. It is predicted that all hyperthermophilic ?-keto acids ferredoxin oxidoreductases are bifunctional, catalyzing the activities of nonoxidative and oxidative decarboxylation of the corresponding ?-keto acids. PMID:24982594

  11. A Bifunctional Enzyme That Has Both Monoacylglycerol Acyltransferase and Acyl Hydrolase Activities1[W][OA

    PubMed Central

    Vijayaraj, Panneerselvam; Jashal, Charnitkaur B.; Vijayakumar, Anitha; Rani, Sapa Hima; Venkata Rao, D.K.; Rajasekharan, Ram

    2012-01-01

    Monoacylglycerol acyltransferase (MGAT) catalyzes the synthesis of diacylglycerol, the precursor of triacylglycerol biosynthesis and an important signaling molecule. Here, we describe the isolation and characterization of the peanut (Arachis hypogaea) MGAT gene. The soluble enzyme utilizes invariant histidine-62 and aspartate-67 residues of the acyltransferase motif for its MGAT activity. A sequence analysis revealed the presence of a hydrolase (GXSXG) motif, and enzyme assays revealed the presence of monoacylglycerol (MAG) and lysophosphatidylcholine (LPC) hydrolytic activities, indicating the bifunctional nature of the enzyme. The overexpression of the MGAT gene in yeast (Saccharomyces cerevisiae) caused an increase in triacylglycerol accumulation. Similar to the peanut MGAT, the Arabidopsis (Arabidopsis thaliana) homolog (At1g52760) also exhibited both acyltransferase and hydrolase activities. Interestingly, the yeast homolog lacks the conserved HX4D motif, and it is deficient in the acyltransferase function but exhibits MAG and LPC hydrolase activities. This study demonstrates the presence of a soluble MGAT/hydrolase in plants. The predicted three-dimensional homology modeling and substrate docking suggested the presence of two separate substrate (MAG and LPC)-binding sites in a single polypeptide. Our study describes a soluble bifunctional enzyme that has both MGAT and hydrolase functions. PMID:22915575

  12. Study of Catcher Bearings for High Temperature Magnetic Bearing Application 

    E-print Network

    Narayanaswamy, Ashwanth

    2011-08-08

    for catcher bearing material need to be done. A dynamic model needs to be designed for studying and simulating the rotor drop of the shaft onto the catcher bearing using a finite element approach in MATLAB. The assembly of the test rig was completed...

  13. Superconducting levitating bearing

    NASA Technical Reports Server (NTRS)

    Moon, Francis C. (Inventor)

    1996-01-01

    A superconducting bearing assembly includes a coil field source that may be superconducting and a superconducting structure. The coil field source assembly and superconducting structure are positioned so as to enable relative rotary movement therebetween. The structure and coil field source are brought to a supercooled temperature before a power supply induces a current in the coil field source. A Meissner-like effect is thereby obtained and little or no penetration of the field lines is seen in the superconducting structure. Also, the field that can be obtained from the superconducting coil is 2-8 times higher than that of permanent magnets. Since the magnetic pressure is proportioned to the square of the field, magnetic pressures from 4 to 64 times higher are achieved.

  14. Bifunctional cinchona alkaloid-squaramide-catalyzed highly enantioselective aza-Michael addition of indolines to ?,?-unsaturated ketones.

    PubMed

    Ghosh, Arun K; Zhou, Bing

    2013-07-01

    An enantioselective aza-Michael addition of indolines to ?,?-unsaturated ketones was achieved using a bifunctional cinchona alkaloid-derived chiral squaramide derivative. Various ?-indolinyl ketone derivatives were obtained in good to excellent yields and with high enantioselectivity. DDQ or MnO2 oxidation of indoline derivatives provided convenient access to various enantioenriched N-substituted indole derivatives. PMID:24014895

  15. Cobalt nanoparticles embedded in N-doped carbon as an efficient bifunctional electrocatalyst for oxygen reduction and evolution reactions.

    PubMed

    Su, Yunhe; Zhu, Yihua; Jiang, Hongliang; Shen, Jianhua; Yang, Xiaoling; Zou, Wenjian; Chen, Jianding; Li, Chunzhong

    2014-12-21

    Cobalt based catalysts are promising bifunctional electrocatalysts for both oxygen reduction and oxygen evolution reactions (ORR and OER) in unitized regenerative fuel cells (URFCs) operating with alkaline electrolytes. Here we report a hybrid composite of cobalt nanoparticles embedded in nitrogen-doped carbon (Co/N-C) via a solvothermal carbonization strategy. With the synergistic effect arising from the N-doped carbon and cobalt nanoparticles in the composite, the Co/N-C hybrid catalyst exhibits highly efficient bifunctional catalytic activity and excellent stability toward both ORR and OER. The ?E (oxygen electrode activity parameter for judging the overall electrocatalytic activity of a bifunctional electrocatalyst) value for Co/N-C is 0.859 V, which is smaller than those of Pt/C and most of the non-precious metal catalysts in previous studies. Furthermore, the Co/N-C composite also shows better bifunctional catalytic activity than its oxidative counterparts, which could be attributed to the high specific surface area and the efficient charge transfer ability of the composite, as well as the good synergistic effect between N-doped carbon and the Co nanoparticles in the Co/N-C composite. PMID:25369741

  16. Electrochemical studies of an unsupported PtIr electrocatalyst as a bifunctional oxygen electrode in a unitized regenerative fuel cell

    Microsoft Academic Search

    Ho-Young Jung; Branko N. Popov

    2009-01-01

    The electrochemical performance of an unsupported PtIr electrocatalyst was evaluated as a bifunctional oxygen electrode in a unitized regenerative fuel cell (URFC). The catalyst was a mixture of unsupported Pt black and Ir black catalysts in varying proportions. The performance of the unsupported PtIr catalyst was studied by using a rotating ring disc electrode (RRDE) and linear sweep voltammetry (LSV).

  17. Introduction to magnetic bearings

    NASA Technical Reports Server (NTRS)

    Skowronski, Lori; Bisese, Anne

    1993-01-01

    Multi-axis suspension has several advantages over single axis system, in that it provides control of an object with precision in two or three orthogonal axes. In this report, we discuss the primary use of magnetic-bearing suspension and it's relevance to what was formally known as NASA's Annular Suspension and Pointing System (ASPS). This system is an experimental pointing system with applications for the space shuttle and the space station programs. The objectives behind this magnetic suspension research project are to provide insight to the use of the ASPS configuration, to control the solar panels of the space station. This is important to maintain the correct position of the panels in relation to the sun and orbiting space station for the continuous supply of solar energy. Since the panels are suspended, they can be aligned with minimum outside interference. The approach of using magnetic suspension technology guarantees mechanical isolation since there are no contacting surfaces. This isolation reduces vibration transmission and mechanical wear which in turn extends the life of the payload and of the carrier. It should be noted that ASPS has a high pointing accuracy along the line of 0.01 arc-second. This research will be done in a laboratory setting by incorporating five bearing stations and one motion control station. We will attempt to suspend an object of dead weight similar to that of a solar panel. The long term applications may include deep-space navigation, fire control in weapon systems, and an improved mass transit system.

  18. Adaptive Spindle Balancing Using Magnetically Levitated Bearings

    Microsoft Academic Search

    PATRICK S. BARNEY; JAMES P. LAUFFER; REBECCA PETTEYS; JAMES M. REDMOND; WILLIAM N. SULLIVAN

    1999-01-01

    A technological break through for supporting rotating shafts is the active magnetic bearing (AMB). Active magnetic bearings offer some important advantages over conventional ball, roller or journal bearings such as reduced frictional drag, no physical contact in the bearing, no need for lubricants, compatibility with high vacuum and ultra-clean environments, and ability to control shaft position within the bearing. The

  19. Service Lives Of Restored Bearings

    NASA Technical Reports Server (NTRS)

    Zaretsky, Erwin V.

    1988-01-01

    Rebuilt units last almost as long as new ones. Report describes theoretical and experiemental studies of lifetimes of restored ball and cylindrical-roller bearings. Results of this and related studies have implications of economy and safety in modern high-speed machinery, especially in aircraft industry, where inspection and rejection or replacing of bearings are new standard practice.

  20. Zero-Deadband Ball Bearings

    NASA Technical Reports Server (NTRS)

    Hine, Michael J.

    1988-01-01

    Proposed supports for ball bearings press outer races against balls without radial clearance. Diaphragm-like axially flexible springs eliminate deadband and consequent nonlinear radial vibrational response of rotor. If shaft needs two bearings at each end, they are supported independently or connected in series by U-spring. Mechanical stops limit axial travel of shaft.

  1. Polar Bears and Climate Change

    NSDL National Science Digital Library

    Andrew E. Derocher (University of Alberta, Canada; )

    2008-05-01

    The issue-focused, peer reviewed article discusses how a warming climate is altering sea ice conditions, which affects polar bears in many ways, including more difficulty in getting to and hunting prey, fewer den areas and lower cub survival, increased interactions between bears and humans, and lower survival rate of the species in general.

  2. 77 FR 70423 - Black Bear Hydro Partners, LLC and Black Bear Development Holdings, LLC and Black Bear SO, LLC...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-11-26

    ...Federal Energy Regulatory Commission [Project Nos. 2710-061; 2712-078] Black Bear Hydro Partners, LLC and Black Bear Development Holdings, LLC and Black Bear SO, LLC; Notice of Application for Partial Transfer of Licenses, and...

  3. Immobilization of Wyoming bears using carfentanil and xylazine.

    PubMed

    Kreeger, Terry J; Bjornlie, Dan; Thompson, Dan; Clapp, Justin; Clark, Colby; Hansen, Cole; Huizenga, Matt; Lockwood, Sam

    2013-07-01

    Seven grizzly (Ursus arctos; four male, three female) and three black (Ursus americanus; two male, one female) bears caught in culvert traps or leg snares were immobilized in northwestern Wyoming with carfentanil and xylazine at doses, respectively, of 0.011 ± 0.001 and 0.12 ± 0.01 mg/kg for grizzly bears and 0.014 ± 0.002 and 0.15 ± 0.04 mg/kg for black bears. These drugs were antagonized with 1 mg/kg naltrexone and 2 mg/kg tolazoline. Induction and recovery times, respectively, were 4.3 ± 0.5 and 7.1 ± 0.8 min for grizzly bears and 5.2 ± 0.4 and 9.1 ± 2.2 min for black bears. Inductions were smooth and uneventful. Recoveries were characterized initially by increased respiration followed by raising of the head, which quickly led to a full recovery, with the bears recognizing and avoiding humans and moving away, maneuvering around obstacles. All bears experienced respiratory depression, which did not significantly improve with supplemental oxygen on the basis of pulse oximetry (P=0.56). Rectal temperatures were normothermic. Carfentanil-xylazine immobilization of bears provided significant advantages over other drug regimens, including small drug volumes, predictable inductions, quick and complete recoveries, and lower costs. On the basis of these data, both grizzly and black bears can be immobilized effectively with 0.01 mg/kg carfentanil and 0.1 mg/kg xylazine. PMID:23778620

  4. Superconducting meissner effect bearings for cryogenic turbomachines. Interim report, 1 November 1989-31 December 1990

    SciTech Connect

    Iannello, V.

    1991-02-27

    This report describes the first year efforts to develop a miniature, high speed superconducting bearing system suitable for cryogenic turbomachines such as miniature turboexpanders used in spaceborne cryocoolers for surveillance sensors. A bearing breadboard was designed, fabricated, and tested to a rotational speed of 450,000 rpm. Numerical models were developed to predict levitation focus between superconductors and permanent magnets, and validated with experimental data. The design of the turbomachine was initiated, including the conceptualization of a novel bearing system.

  5. 49 CFR 229.64 - Plain bearings.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 2013-10-01 2013-10-01 false Plain bearings. 229.64 Section 229.64 Transportation...Requirements Suspension System § 229.64 Plain bearings. A plain bearing box shall contain visible free oil and may not...

  6. 49 CFR 229.64 - Plain bearings.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 2011-10-01 2011-10-01 false Plain bearings. 229.64 Section 229.64 Transportation...Requirements Suspension System § 229.64 Plain bearings. A plain bearing box shall contain visible free oil and may not...

  7. 49 CFR 229.64 - Plain bearings.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 2012-10-01 2012-10-01 false Plain bearings. 229.64 Section 229.64 Transportation...Requirements Suspension System § 229.64 Plain bearings. A plain bearing box shall contain visible free oil and may not...

  8. 49 CFR 229.64 - Plain bearings.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 2010-10-01 2010-10-01 false Plain bearings. 229.64 Section 229.64 Transportation...Requirements Suspension System § 229.64 Plain bearings. A plain bearing box shall contain visible free oil and may not...

  9. 49 CFR 229.64 - Plain bearings.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 2014-10-01 2014-10-01 false Plain bearings. 229.64 Section 229.64 Transportation...Requirements Suspension System § 229.64 Plain bearings. A plain bearing box shall contain visible free oil and may not...

  10. Structures of a bifunctional cell wall hydrolase CwlT containing a novel bacterial lysozyme and an NlpC/P60 DL-endopeptidase.

    PubMed

    Xu, Qingping; Chiu, Hsiu-Ju; Farr, Carol L; Jaroszewski, Lukasz; Knuth, Mark W; Miller, Mitchell D; Lesley, Scott A; Godzik, Adam; Elsliger, Marc-André; Deacon, Ashley M; Wilson, Ian A

    2014-01-01

    Tn916-like conjugative transposons carrying antibiotic resistance genes are found in a diverse range of bacteria. Orf14 within the conjugation module encodes a bifunctional cell wall hydrolase CwlT that consists of an N-terminal bacterial lysozyme domain (N-acetylmuramidase, bLysG) and a C-terminal NlpC/P60 domain (?-d-glutamyl-l-diamino acid endopeptidase) and is expected to play an important role in the spread of the transposons. We determined the crystal structures of CwlT from two pathogens, Staphylococcus aureus Mu50 (SaCwlT) and Clostridium difficile 630 (CdCwlT). These structures reveal that NlpC/P60 and LysG domains are compact and conserved modules, connected by a short flexible linker. The LysG domain represents a novel family of widely distributed bacterial lysozymes. The overall structure and the active site of bLysG bear significant similarity to other members of the glycoside hydrolase family 23 (GH23), such as the g-type lysozyme (LysG) and Escherichia coli lytic transglycosylase MltE. The active site of bLysG contains a unique structural and sequence signature (DxxQSSES+S) that is important for coordinating a catalytic water. Molecular modeling suggests that the bLysG domain may recognize glycan in a similar manner to MltE. The C-terminal NlpC/P60 domain contains a conserved active site (Cys-His-His-Tyr) that appears to be specific to murein tetrapeptide. Access to the active site is likely regulated by isomerism of a side chain atop the catalytic cysteine, allowing substrate entry or product release (open state), or catalysis (closed state). PMID:24051416

  11. Structures of a bifunctional cell-wall hydrolase CwlT containing a novel bacterial lysozyme and an NlpC/P60 dl-endopeptidase

    PubMed Central

    Xu, Qingping; Chiu, Hsiu-Ju; Farr, Carol L.; Jaroszewski, Lukasz; Knuth, Mark W.; Miller, Mitchell D.; Lesley, Scott A.; Godzik, Adam; Elsliger, Marc-André; Deacon, Ashley M.; Wilson, Ian A.

    2013-01-01

    Tn916-like conjugative transposons carrying antibiotic resistance genes are found in a diverse range of bacteria. Orf14 within the conjugation module encodes a bifunctional cell-wall hydrolase CwlT that consists of an N-terminal bacterial lysozyme domain (N-acetylmuramidase, bLysG) and a C-terminal NlpC/P60 domain (?-d-glutamyl-l-diamino acid endopeptidase) and is expected to play an important role in the spread of the transposons. We determined the crystal structures of two CwlT from pathogens Staphylococcus aureus mu50 (SaCwlT) and Clostridium difficile 630 (CdCwlT). These structures reveal that NlpC/P60 and LysG domains are compact and conserved modules, connected by a short flexible linker. The LysG domain represents a novel family of widely distributed bacterial lysozymes. The overall structure and the active site of bLysG bear significant similarity to other members of the glycoside hydrolase family 23 (GH23), such as the g-type lysozyme (LysG) and Escherichia coli lytic transglycosylase MltE. The active site of bLysG contains a unique structural and sequence signature (DxxQSSES+S) that is important for coordinating a catalytic water. Molecular modeling suggests that the bLysG domain may recognize glycan in a similar manner to MltE. The C-terminal NlpC/P60 domain contains a conserved active site (Cys-His-His-Tyr) that appears to be specific for tetrapeptide. Access to the active site is likely regulated by isomerism of a side chain atop the catalytic cysteine, allowing substrate entry or product release, or closing during catalysis. PMID:24051416

  12. Analysis of foil bearings for high speed operation in cryogenic applications

    NASA Technical Reports Server (NTRS)

    Carpino, Marc

    1991-01-01

    The general objective of this project is to develop analysis tools which are required for the design of foil bearings to be used in cryogenic applications. During the second year of this project, a general analysis approach and code for journal bearings operating under steady state conditions will be completed. This will be followed by the initiation of an investigation into transient behavior of foil bearings to determine their performance in rotor systems. Foil bearings have been proposed as an alternative to rolling element bearings for use in cryogenic turbopumps in liquid propellant rocket engines. This type of bearing offers several advantages over rolling element bearings since they would use the cryogenic pump fluid for a lubricant and have structural flexibility. These bearings have the potential of high reliability and long life. The bearing surface is constructed of a 'foil' which resists deflection by a combination of bending, membrane, and elastic foundation effects. The relative motion between the rotating shaft and the foil causes pressure in the fluid film to develop. This pressure deflects the the foil surface away from the shaft. Once a full fluid film is established between the foil and the rotor shaft, contact no longer takes place and there is no subsequent wear of the surfaces. The flexible foil structure of the bearing allows it to compensate for minor tolerance and manufacturing defects. This same flexibility also has a significant effect on the dynamic performance of the rotor-bearing system.

  13. Magnetic Bearings at Draper Laboratory

    NASA Technical Reports Server (NTRS)

    Kondoleon, Anthony S.; Kelleher, William P.; Possel, Peter D.

    1996-01-01

    Magnetic bearings, unlike traditional mechanical bearings, consist of a series of components mated together to form a stabilized system. The correct design of the actuator and sensor will provide a cost effective device with low power requirements. The proper choice of a control system utilizes the variables necessary to control the system in an efficient manner. The specific application will determine the optimum design of the magnetic bearing system including the touch down bearing. Draper for the past 30 years has been a leader in all these fields. This paper summarizes the results carried out at Draper in the field of magnetic bearing development. A 3-D radial magnetic bearing is detailed in this paper. Data obtained from recently completed projects using this design are included. One project was a high radial load (1000 pound) application. The second was a high speed (35,000 rpm), low loss flywheel application. The development of a low loss axial magnetic bearing is also included in this paper.

  14. SSME turbopump bearing analytical study

    NASA Technical Reports Server (NTRS)

    Kannel, J. W.; Merriman, T.

    1980-01-01

    Three shuttle pump bearings operating under severe overspeed and shut-down conditions are evaluated. The specific parameters investigated include outer race stresses, cage stresses, cage-race drag, bearing heating, and crush loading. A quasi-dynamic version of the BASDAP computer code was utilized which involved the calculation of ball-race forces (inner and outer), contact pressures, contact dimensions, and contact angles as a function of (1) axial load, (2) radial load, and (3) centrifugal load on the bearing. Generally, radial loads on the order of 13,300 N (3000 pounds) per bearing or 26,700 N (6000 pounds) per bearing pair, could be expected to cause severe problems to any of the bearings with a 17,800 N (4000 pounds) axial load. Further, when possible temperature excursions are considered, even a load of 8900 N (2000 pounds) may be excessive. However, high momentary radial loads with a 3800 N (850 pounds) axial load would not be anticipated to cause catastrophic failure of the fuel pump bearing.

  15. Random Bearings and Their Stability

    NASA Astrophysics Data System (ADS)

    Baram, Reza Mahmoodi; Herrmann, Hans J.

    2005-11-01

    Self-similar space-filling bearings have been proposed some time ago as models for the motion of tectonic plates and appearance of seismic gaps. These models have two features which, however, seem unrealistic, namely, high symmetry in the arrangement of the particles, and lack of a lower cutoff in the size of the particles. In this work, an algorithm for generating random bearings in both two and three dimensions is presented. Introducing a lower cutoff for the sizes of the particles, the instabilities of the bearing under an external force such as gravity, are studied.

  16. Bypass control valve seal and bearing life cycle test report

    NASA Technical Reports Server (NTRS)

    Lundback, A. V.

    1972-01-01

    The operating characteristics of a bypass control valve seal and bearing life cycle tests are reported. Data from the initial assembly, leak, torque, and deflection tests are included along with the cycle life test results and conclusions. The equipment involved was to be used in the nuclear engine for the rocket vehicles program.

  17. Grease Inhibits Stress-Corrosion Cracking In Bearing Race

    NASA Technical Reports Server (NTRS)

    Beatty, Robert F.; Mcvey, Scott E.

    1991-01-01

    Coating with suitable grease found to inhibit stress-corrosion cracking in bore of inner race of ball-bearing assembly operating in liquid oxygen. Protects bore and its corner radii from corrosion-initiating and -accelerating substances like moisture and contaminants, which enter during assembly. Operating life extended at low cost, and involves very little extra assembly time.

  18. Detection of rolling element bearing defects by adaptive filtering

    Microsoft Academic Search

    Imed Khemili; Mnaouar Chouchane

    2005-01-01

    Most of the difficulties encountered when detecting initial bearing defects are due to the presence of noise in the measured signals. In the present paper, we show the effectiveness of using Adaptive Noise Cancellation techniques, in enhancing the vibration signal which is corrupted with noise in the low frequency spectrum. Two algorithms have been used in the paper, the Adaptive

  19. Ontogenetic Habitat Shifts of Juvenile Bear Lake Sculpin

    Microsoft Academic Search

    James R. Ruzycki; Wayne A. Wurtsbaugh

    1999-01-01

    Bear lake sculpin Cottus extensus exhibit ontogenetic habitat shifts during their initial year of life. Distribution and habitat switching was measured with bimonthly bottom-trawl surveys repeated throughout the summer. Patterns of daily growth increments on otoliths were used to measure the history of habitat residence, individual size at the time of the habitat switch, and habitat-specific growth rates. Laboratory experiments

  20. Bi-functional biobased packing of the cassava starch, glycerol, licuri nanocellulose and red propolis.

    PubMed

    Costa, Samantha Serra; Druzian, Janice Izabel; Machado, Bruna Aparecida Souza; de Souza, Carolina Oliveira; Guimarães, Alaíse Gil

    2014-01-01

    The aim of this study was to characterize and determine the bi-functional efficacy of active packaging films produced with starch (4%) and glycerol (1.0%), reinforced with cellulose nanocrystals (0-1%) and activated with alcoholic extracts of red propolis (0.4 to 1.0%). The cellulose nanocrystals used in this study were extracted from licuri leaves. The films were characterized using moisture, water-activity analyses and water vapor-permeability tests and were tested regarding their total phenolic compounds and mechanical properties. The antimicrobial and antioxidant efficacy of the films were evaluated by monitoring the use of the active films for packaging cheese curds and butter, respectively. The cellulose nanocrystals increased the mechanical strength of the films and reduced the water permeability and water activity. The active film had an antimicrobial effect on coagulase-positive staphylococci in cheese curds and reduced the oxidation of butter during storage. PMID:25383783

  1. Bifunctional nanoparticles for SERS monitoring and magnetic intervention of assembly and enzyme cutting of DNAs

    SciTech Connect

    Lin, Liqin; Crew, Elizabeth; Yan, Hong; Shan, Shiyao; Skeete, Zakiya; Mott, Derrick; Krentsel, Tatiana; Yin, Jun; Chernova, Natasha A.; Luo, Jin; Engelhard, Mark H.; Wang, Chong M.; Li, Qingbiao; Zhong, Chuan-Jian

    2013-07-27

    The ability to detect and intervene in DNA assembly, disassembly, and enzyme cutting processes in a solution phase requires effective signal transduction and stimulus response. This report demonstrates a novel bifunctional strategy for the creation of this ability using gold- and silver-coated MnZn ferrite nanoparticles (MZF@Au or MZF@Ag) that impart magnetic and surfaceenhanced Raman scattering (SERS) functionalities to these processes. The double-stranded DNA linkage of labeled gold nanoparticles with MZF@Au (or MZF@Ag) produces interparticle "hot-spots" for real-time SERS monitoring of the DNA assembly, disassembly, or enzyme cutting processes, during which the magnetic component provides an effective means for intervention in the solution. The unique combination of the nanoprobes functionalities serves a new paradigm for the design of functional nanoprobes in biomolecular recognition and intervention.

  2. The inner synergistic effect of bifunctional ionic liquid extractant for solvent extraction.

    PubMed

    Sun, Xiaoqi; Ji, Yang; Hu, Fengchun; He, Bo; Chen, Ji; Li, Deqian

    2010-06-15

    The inner synergistic effect of bifunctional ionic liquid extractant (Bif-ILE) for solvent extraction is reported for the first time using [tricaprylmethylammonium][di-2-ethylhexylphosphinate] ([A336][P204]) as n extractant for Eu(III), which can be attributed to better stability and hydrophobicity of the complex formed by [A336][P204] with Eu(III). Some other Bif-ILEs are also found to have the similar inner synergistic effect. Distribution coefficient, stripping property and extraction mechanism of the novel extraction protocol are discussed in this report. The study contributes towards acquiring a new understanding of synergistic extraction and task specific ionic liquid (TSIL), furthermore, providing a positive influence on their potential application in analytical chemistry. PMID:20441990

  3. Pure blue-light emissive poly(oligofluorenes) with bifunctional poss in the main chain.

    PubMed

    Chi, Hong; Lim, Siew Lay; Wang, Fuke; Wang, Xizu; He, Chaobin; Chin, Wee Shong

    2014-04-01

    Emission of conjugated polymers is known to undergo bathochromic shift from solution to film formation due to ?-? stacking in the solid state. In this report, a series of pearl-necklace-like hybrid polymers is designed via the hydrosilylation condensation between bifunctional polyhedral oligomeric silsesquioxanes (B-POSS) and oligofluorene segments. Optoelectronic analyses unequivocally show that the presence of these interconnecting B-POSS can effectively reduce red-shift in photoluminescence and electroluminescence during film formation. These hybrid poly(oligofluorenes) display stable blue emission with high color purity. Thermal analyses also indicate that they are vitrified polymers with high glass transition temperature (up to 125 °C). We believe that this strategy can be extended to other conjugated systems to control color purity in electroactive materials and holds promise as new emissive materials for various applications. PMID:24677615

  4. Differential response of familial polyposis fibroblasts to two bifunctional alkylating agents.

    PubMed

    Friedman, E; Carnright, K; Lipkin, M

    1982-01-01

    Skin fibroblasts from three subjects with familial polyposis coli, a hereditary disorder predisposing to colon cancer, exhibited an unexpected insensitivity to mitomycin C (MMC). Sister chromatid exchanges (SCEs) were either reduced or unchanged after exposure to MMC, while another bi-functional alkylating agent, diepoxybutane (DEB), induced an increase in SCE level at a low, equitoxic dosage in parallel experiments. Increased sensitivity to MMC as assayed by colony formation was, however, shown by one of the subjects with polyposis. These cells with the familial polyposis genotype may have a deficiency in the DNA repair system handling MMC-induced alkylation damage yet remain capable of repairing damage induced by DEB alkylation. This deficiency may contribute to the increased frequency of neoplastic transformation known to occur in these cells in vivo. PMID:7151262

  5. SCO5745, a bifunctional RNase J ortholog, affects antibiotic production in Streptomyces coelicolor.

    PubMed

    Bralley, Patricia; Aseem, Madiha; Jones, George H

    2014-03-01

    The bacterial RNases J are considered bifunctional RNases possessing both endo- and exonucleolytic activities. We have isolated an RNase J ortholog from Streptomyces coelicolor encoded by the gene sco5745. We overexpressed a decahistidine-tagged version of SCO5745 and purified the overexpressed protein by immobilized metal ion affinity chromatography. We demonstrated the presence of both 5'-to-3' exonucleolytic and endonucleolytic activities on the Bacillus subtilis thrS transcript. Exonucleoytic activity predominated with 5' monophosphorylated thrS, while endonucleolytic activity predominated with 5' triphosphorylated thrS. While sco5745 is the only RNase J allele in S. coelicolor, the gene is not essential. Its disruption resulted in delayed production of the antibiotic actinorhodin, overproduction of undecylprodigiosin, and diminished production of the calcium-dependent antibiotic, in comparison with the parental strain. PMID:24415725

  6. SCO5745, a Bifunctional RNase J Ortholog, Affects Antibiotic Production in Streptomyces coelicolor

    PubMed Central

    Bralley, Patricia; Aseem, Madiha

    2014-01-01

    The bacterial RNases J are considered bifunctional RNases possessing both endo- and exonucleolytic activities. We have isolated an RNase J ortholog from Streptomyces coelicolor encoded by the gene sco5745. We overexpressed a decahistidine-tagged version of SCO5745 and purified the overexpressed protein by immobilized metal ion affinity chromatography. We demonstrated the presence of both 5?-to-3? exonucleolytic and endonucleolytic activities on the Bacillus subtilis thrS transcript. Exonucleoytic activity predominated with 5? monophosphorylated thrS, while endonucleolytic activity predominated with 5? triphosphorylated thrS. While sco5745 is the only RNase J allele in S. coelicolor, the gene is not essential. Its disruption resulted in delayed production of the antibiotic actinorhodin, overproduction of undecylprodigiosin, and diminished production of the calcium-dependent antibiotic, in comparison with the parental strain. PMID:24415725

  7. Bi-Functional Biobased Packing of the Cassava Starch, Glycerol, Licuri Nanocellulose and Red Propolis

    PubMed Central

    Costa, Samantha Serra; Druzian, Janice Izabel; Machado, Bruna Aparecida Souza; de Souza, Carolina Oliveira; Guimarães, Alaíse Gil

    2014-01-01

    The aim of this study was to characterize and determine the bi-functional efficacy of active packaging films produced with starch (4%) and glycerol (1.0%), reinforced with cellulose nanocrystals (0–1%) and activated with alcoholic extracts of red propolis (0.4 to 1.0%). The cellulose nanocrystals used in this study were extracted from licuri leaves. The films were characterized using moisture, water-activity analyses and water vapor-permeability tests and were tested regarding their total phenolic compounds and mechanical properties. The antimicrobial and antioxidant efficacy of the films were evaluated by monitoring the use of the active films for packaging cheese curds and butter, respectively. The cellulose nanocrystals increased the mechanical strength of the films and reduced the water permeability and water activity. The active film had an antimicrobial effect on coagulase-positive staphylococci in cheese curds and reduced the oxidation of butter during storage. PMID:25383783

  8. Crystal structure of a bifunctional aldolase–dehydrogenase: Sequestering a reactive and volatile intermediate

    PubMed Central

    Manjasetty, Babu A.; Powlowski, Justin; Vrielink, Alice

    2003-01-01

    The crystal structure of the bifunctional enzyme 4-hydroxy-2-ketovalerate aldolase (DmpG)/acylating acetaldehyde dehydrogenase (DmpF), which is involved in the bacterial degradation of toxic aromatic compounds, has been determined by multiwavelength anomalous dispersion (MAD) techniques and refined to 1.7-Å resolution. Structures of the two polypeptides represent a previously unrecognized subclass of metal-dependent aldolases, and of a CoA-dependent dehydrogenase. The structure reveals a mixed state of NAD+ binding to the DmpF protomer. Domain movements associated with cofactor binding in the DmpF protomer may be correlated with channeling and activity at the DmpG protomer. In the presence of NAD+ a 29-Å-long sequestered tunnel links the two active sites. Two barriers are visible along the tunnel and suggest control points for the movement of the reactive and volatile acetaldehyde intermediate between the two active sites. PMID:12764229

  9. Development of tartaric esters as bifunctional additives of methanol-gasoline

    PubMed Central

    2014-01-01

    Background Methanol has become an alternative fuel for gasoline, which is facing a rapidly rising world demand with a limited oil supply. Methanol-gasoline has been used in China, but phase stability and vapor lock still need to be resolved in methanol-gasoline applications. In this paper, a series of tartaric esters were synthesized and used as phase stabilizers and saturation vapor pressure depressors for methanol-gasoline. Results The results showed that the phase stabilities of tartaric esters for methanol-gasoline depend on the length of the alkoxy group. Several tartaric esters were found to be effective in various gasoline-methanol blends, and the tartaric esters display high capacity to depress the saturation vapor pressure of methanol-gasoline. Conclusion According to the results, it can be concluded that the tartaric esters have great potential to be bifunctional gasoline-methanol additives. PMID:24731649

  10. On the molecular basis of D-bifunctional protein deficiency type III.

    PubMed

    Mehtälä, Maija L; Lensink, Marc F; Pietikäinen, Laura P; Hiltunen, J Kalervo; Glumoff, Tuomo

    2013-01-01

    Molecular basis of D-bifunctional protein (D-BP) deficiency was studied with wild type and five disease-causing variants of 3R-hydroxyacyl-CoA dehydrogenase fragment of the human MFE-2 (multifunctional enzyme type 2) protein. Complementation analysis in vivo in yeast and in vitro enzyme kinetic and stability determinants as well as in silico stability and structural fluctuation calculations were correlated with clinical data of known patients. Despite variations not affecting the catalytic residues, enzyme kinetic performance (K(m), V(max) and k(cat)) of the recombinant protein variants were compromised to a varying extent and this can be judged as the direct molecular cause for D-BP deficiency. Protein stability plays an additional role in producing non-functionality of MFE-2 in case structural variations affect cofactor or substrate binding sites. Structure-function considerations of the variant proteins matched well with the available data of the patients. PMID:23308274

  11. Increased Catalytic Efficiency Following Gene Fusion of Bifunctional Methionine Sulfoxide Reductase Enzymes from Shewanella oneidensis

    SciTech Connect

    Chen, Baowei; Markillie, Lye Meng; Xiong, Yijia; Mayer, M. Uljana; Squier, Thomas C.

    2007-11-11

    Methionine sulfoxide reductase enzymes MsrA and MsrB have complementary stereospecificies that respectively reduce the S- and R-stereoisomers of methionine sulfoxide (MetSO), and together function as critical antioxidant enzymes. In some pathogenic and metal reducing bacteria these genes are fused to form a bifunctional methionine sulfoxide reductase (i.e., MsrBA) enzyme. To investigate the impact of gene fusion on the substrate specificity and catalytic activities of Msr, we have cloned and expressed the MsrBA enzyme from Shewanella oneidensis, a metal reducing bacterium and fish pathogen. For comparison, we also cloned and expressed the wild-type MsrA enzyme and a genetically engineered MsrB protein. We report that MsrBA is able to completely reduce (i.e., repair) MetSO in the calcium regulatory protein calmodulin; in comparison only partial repair is observed using both MsrA and MsrB enzymes together at 25 °C. MsrBA has a twenty-fold enhanced rate of repair for MetSO in proteins in comparison with the individual MsrA or MsrB enzymes alone and respective 14- and 50-fold increases in catalytic efficiency (i.e., kcat/KM). In comparison, MsrBA and MsrA have similar catalytic efficiencies when free MetSO is used as a substrate. These results indicate that the individual domains within bifunctional MsrBA work cooperatively to selectively recognize and reduce MetSO in highly oxidized proteins. The enhanced catalytic activity of MsrBA against oxidized proteins and its common expression in bacterial pathogens is consistent with an important role for this enzyme activity in promoting bacterial survival under highly oxidizing conditions associated with pathogenesis or bioremediation.

  12. Active sites in working bifunctional GaH-TON aromatization catalysts: kinetic evaluation.

    PubMed

    Lukyanov, Dmitry B; Vazhnova, Tanya

    2006-09-21

    The conversion of light alkanes to high value aromatics proceeds with a high selectivity over bifunctional, gallium (Ga) containing zeolite catalysts. It is generally agreed that Ga sites are involved in dehydrogenation reaction steps and that the zeolite acid sites catalyze cracking, oligomerization, and cyclization reactions. However, understanding of the precise roles of the acid and Ga sites in the reaction mechanisms is significantly hampered since the number of these sites in working catalysts is not known. This paper describes a kinetic approach to evaluation of the acid and Ga active sites in working Ga containing TON zeolite catalysts that relies on the analysis of the rates of formation of the primary products of a n-butane aromatization reaction. Our results show that the rate of ethane formation at low n-butane conversions can be used as a quantitative estimate of acidity in working bifunctional zeolite catalysts and demonstrate, for the first time, a significant decrease in the number of Brønsted acid sites in the Ga containing catalysts under reaction conditions: around 47 and 79% for the catalysts with Ga loading of 1.5 and 2.5 wt %, respectively. We conclude that the reduction in acidity is associated with the formation of catalytically active Ga(+) ions and obtain estimates for the number and steady-state turnover activity of the acid and Ga active sites in n-butane transformation. We anticipate that our work will facilitate understanding of the precise roles of the acid and Ga sites in the mechanisms of alkane aromatization and, as a far-reaching implication, will prompt wider use of detailed kinetic studies for the evaluation of active sites in working catalysts. PMID:16970474

  13. Purification and Characterization of a Bifunctional Alginate Lyase from Pseudoalteromonas sp. SM0524

    PubMed Central

    Li, Jian-Wei; Dong, Sheng; Song, Jie; Li, Chun-Bo; Chen, Xiu-Lan; Xie, Bin-Bin; Zhang, Yu-Zhong

    2011-01-01

    An alginate lyase-producing bacterial strain, Pseudoalteromonas sp. SM0524, was screened from marine rotten kelp. In an optimized condition, the production of alginate lyase from Pseudoalteromonas sp. SM0524 reached 62.6 U/mL, suggesting that strain SM0524 is a good producer of alginate lyases. The bifunctional alginate lyase aly-SJ02 secreted by strain SM0524 was purified. Aly-SJ02 had an apparent molecular mass of 32 kDa. The optimal temperature and pH of aly-SJ02 toward sodium alginate was 50 °C and 8.5, respectively. The half life period of aly-SJ02 was 41 min at 40 °C and 20 min at 50 °C. Aly-SJ02 was most stable at pH 8.0. N-terminal sequence analysis suggested that aly-SJ02 may be an alginate lyase of polysaccharide lyase family 18. Aly-SJ02 showed activities toward both polyG (?-l-guluronic acid) and polyM (?-d-mannuronic acid), indicating that it is a bifunctional alginate lyase. Aly-SJ02 had lower Km toward polyG than toward polyM and sodium alginate. Thin layer chromatography and ESI-MS analyses showed that aly-SJ02 mainly released dimers and trimers from polyM and alginate, and trimers and tetramers from polyG, which suggests that aly-SJ02 may be a good tool to produce dimers and trimers from alginate. PMID:21339950

  14. A novel bifunctional metabolizable linker for the conjugation of antibodies with radionuclides

    SciTech Connect

    Arano, Y.; Matsushima, H.; Tagawa, M.; Koizumi, M.; Endo, K.; Konishi, J.; Yokoyama, A. (Kyoto University (Japan))

    1991-03-01

    A novel heterogeneous bifunctional reagent containing an ester bond, N-((4-(2-maleimidoethoxy)-succinyl)oxy)succinimide (MESS), was designed and synthesized for the conjugation of antibodies with the gallium-67 (67Ga) chelate of succinyldeferoxamine (SDF) via the ester bond. MESS was synthesized by the acylation of N-(2-hydroxyethyl)maleimide with succinic anhydride, followed by the activation of the resulting carboxylic acid to a succinimido ester. MESS possesses a maleimide group for protein conjugation and an active ester group for deferoxamine (DFO) coupling, and the two functional groups are linked via ester bonding. Conjugation of 67Ga-SDF with nonspecific human IgG was performed by reacting freshly thiolated IgG with the reaction product of MESS and DFO, followed by 67Ga labeling of the resulting conjugate using GaCl3 (67Ga-DFO-MESS-IgG). For comparison, 67Ga-DFO conjugated nonspecific human IgG with a nonmetabolizable linkage was synthesized under the same conjugation conditions as those for 67Ga-DFO-MESS-IgG, using a nonmetabolizable heterogenous bifunctional reagent (N-((6-maleimidocaproyl)oxy)succinimide, EMCS) instead of MESS (67Ga-DFO-EMCS-IgG). HPLC size-exclusion chromatography of both preparations showed a single radioactivity and UV peak corresponding to the intact IgG. Generation of 67Ga-SDF from the 67Ga-DFO-MESS-IgG was demonstrated by reverse-phase HPLC analysis and cellulose acetate electrophoresis after the incubation of 67Ga-DFO-MESS-IgG in a buffered solution containing carboxyesterase. After injection of 67Ga-DFO-MESS-IgG into mice, faster radioactivity clearance from the blood and less radioactivity accumulation in the liver, kidney, and spleen was noted than when 67Ga-DFO-EMCS-IgG was injected.

  15. Crystal structure of the bifunctional ATP sulfurylase-APS kinase from the chemolithotrophic thermophile Aquifex aeolicus.

    PubMed

    Yu, Zhihao; Lansdon, Eric B; Segel, Irwin H; Fisher, Andrew J

    2007-01-19

    The thermophilic chemolithotroph, Aquifex aeolicus, expresses a gene product that exhibits both ATP sulfurylase and adenosine-5'-phosphosulfate (APS) kinase activities. These enzymes are usually segregated on two separate proteins in most bacteria, fungi, and plants. The domain arrangement in the Aquifex enzyme is reminiscent of the fungal ATP sulfurylase, which contains a C-terminal domain that is homologous to APS kinase yet displays no kinase activity. Rather, in the fungal enzyme, the motif serves as a sulfurylase regulatory domain that binds the allosteric effector 3'-phosphoadenosine-5'-phosphosulfate (PAPS), the product of true APS kinase. Therefore, the Aquifex enzyme may represent an ancestral homolog of a primitive bifunctional enzyme, from which the fungal ATP sulfurylase may have evolved. In heterotrophic sulfur-assimilating organisms such as fungi, ATP sulfurylase catalyzes the first committed step in sulfate assimilation to produce APS, which is subsequently metabolized to generate all sulfur-containing biomolecules. In contrast, ATP sulfurylase in sulfur chemolithotrophs catalyzes the reverse reaction to produce ATP and sulfate from APS and pyrophosphate. Here, the 2.3 A resolution X-ray crystal structure of Aquifex ATP sulfurylase-APS kinase bifunctional enzyme is presented. The protein dimerizes through its APS kinase domain and contains ADP bound in all four active sites. Comparison of the Aquifex ATP sulfurylase active site with those from sulfate assimilators reveals similar dispositions of the bound nucleotide and nearby residues. This suggests that minor perturbations are responsible for optimizing the kinetic properties for the physiologically relevant direction. The APS kinase active-site lid adopts two distinct conformations, where one conformation is distorted by crystal contacts. Additionally, a disulfide bond is observed in one ATP-binding P-loop of the APS kinase active site. This linkage accounts for the low kinase activity of the enzyme under oxidizing conditions. The thermal stability of the Aquifex enzyme can be explained by the 43% decreased cavity volume found within the protein core. PMID:17095009

  16. Abietadiene synthase from grand fir (Abies grandis). cDNA isolation, characterization, and bacterial expression of a bifunctional diterpene cyclase involved in resin acid biosynthesis.

    PubMed

    Vogel, B S; Wildung, M R; Vogel, G; Croteau, R

    1996-09-20

    (-)-Abietic acid, the principal diterpenoid resin acid of the wound-induced oleoresin secreted by grand fir (Abies grandis), is synthesized by the cyclization of geranylgeranyl diphosphate to (-)-abieta-7(8),13(14)-diene, followed by sequential three-step oxidation of the C-18 methyl group of the olefin to a carboxyl function. The enzyme catalyzing the cyclization reaction, abietadiene synthase, was purified from stems of wounded grand fir saplings and was digested with trypsin. Amino acid sequence information from the resulting peptides allowed construction of degenerate oligonucleotide primers, which amplified a 551-base pair fragment from a wound-induced stem cDNA library. This hybridization probe was then utilized to screen the wound-induced stem cDNA library, from which three cDNA clones were isolated that were functionally expressed in Escherichia coli, thereby confirming that a single protein catalyzes the complex, multistep cyclization of geranylgeranyl diphosphate to abietadiene. cDNA isolate Ac22.1, which yielded the highest expressed level of cyclase activity, was 2861 base pairs in length and encoded an 868-amino acid open reading frame that included a putative plastidial transit peptide. Deduced amino acid sequence comparison to other terpene cyclases revealed an amino-terminal region of the abietadiene synthase, which resembles those of enzymes that employ substrate double bond protonation to initiate the carbocationic reaction cascade, and a carboxyl-terminal region of the synthase, which resembles those of enzymes that employ ionization of the substrate allylic diphosphate ester function to initiate the cyclization reaction. This apparent fusion of segments of the two distinct terpenoid cyclase types is consistent with the novel mechanism of the bifunctional abietadiene synthase in catalyzing both protonation-initiated and ionization-initiated cyclization steps. PMID:8798524

  17. High-temperature bearing lubricants

    NASA Technical Reports Server (NTRS)

    Anderson, W. J.; Parker, R. J.; Zaretsky, E. V.

    1968-01-01

    Synthetic paraffinic oil lubricates ball bearings at temperatures in the 600 degrees F range. The lubricant contains antiwear and antifoam additives, is thermally stable in the high temperature range, but requires protection from oxygen.

  18. ATM CMG bearing failure analysis

    NASA Technical Reports Server (NTRS)

    1975-01-01

    The cause or causes for the failure of ATM CMG S/N 5 (Skylab 1) and the anomalies associated with ATM CMG S/N 6 (Skylab 2) were investigated. Skylab telemetry data were reviewed and presented in the form of parameter distributions. The theory that the problems were caused by marginal bearing lubrication was studied along with the effects of orbital conditions on lubricants. Bearing tests were performed to investigate the effect of lubricant or lack of lubricant in the ATM CMG bearings and the dispersion and migration of the lubricant. The vacuum and weightless conditions of space were simulated in the bearing tests. Analysis of the results of the tests conducted points to inadequate lubrication as the predominant factor causing the failure of ATM CMG S/N 5 (Skylab 1) and the anomalies associated with ATM CMG S/N 6 (Skylab 2).

  19. A Passive Magnetic Bearing Flywheel

    NASA Technical Reports Server (NTRS)

    Siebert, Mark; Ebihara, Ben; Jansen, Ralph; Fusaro, Robert L.; Morales, Wilfredo; Kascak, Albert; Kenny, Andrew

    2002-01-01

    A 100 percent passive magnetic bearing flywheel rig employing no active control components was designed, constructed, and tested. The suspension clothe rotor was provided by two sets of radial permanent magnetic bearings operating in the repulsive mode. The axial support was provided by jewel bearings on both ends of the rotor. The rig was successfully operated to speeds of 5500 rpm, which is 65 percent above the first critical speed of 3336 rpm. Operation was not continued beyond this point because of the excessive noise generated by the air impeller and because of inadequate containment in case of failure. Radial and axial stiffnesses of the permanent magnetic bearings were experimentally measured and then compared to finite element results. The natural damping of the rotor was measured and a damping coefficient was calculated.

  20. Testing and Lubrication for Single Race Bearings

    SciTech Connect

    Steinhoff, R.G.

    1998-03-04

    Three ES and H-compatible lubricants (Environment, Safety and Health) for single race bearing applications and one hybrid-material single race bearings were evaluated and compared against single race bearings with trichlorotrifluoroethane (Freon) deposition of low molecular weight polytetrafluoroethylene (PTFE) bearing lubricant extracted from Vydax{trademark}. Vydax is a product manufactured by DuPont consisting of various molecular weights of PTFE suspended in trichlorotrifluoroethane (Freon), which is an ozone-depleting solvent. Vydax has been used as a bearing lubricant in stronglink mechanisms since 1974. Hybrid bearings with silicon nitride balls and molded glass-nylon-Teflon retainers, bearings lubricated with titanium carbide (TiC) on the balls, bearings lubricated with sputtered MoS{sub 2} on races and retainers, and bearings lubricated with electrophoretically deposited MoS{sub 2} were evaluated. The bearings were maintained in a preloaded state in bearing cartridges during cycling and vibration tests. Bearings with electrophoretically deposited MoS{sub 2} performed as well as bearings lubricated with Vydax and were the best performing candidate. All candidates were suitable for low preload applications. Bearings with TiC coated balls and bearings lubricated with sputtered MoS{sub 2} on the races and retainers performed well at high preloads, though not as well as bearings lubricated with electrophoretic deposition of MoS{sub 2}. Bearings with silicon nitride balls were not suitable for high preload applications.

  1. Improved Superconducting Magnetic Rotary Bearings

    NASA Technical Reports Server (NTRS)

    Flom, Yury; Royston, James

    1992-01-01

    Improved magnetic rotary bearings designed by exploiting properties of type-II superconducting materials. Depending on design and application, bearing provides fixed or adjustable compensation for lateral vector component of weight or other lateral load on rotor. Allows applied magnetic field to penetrate partially in clusters of field lines, with concomitant establishment of undamped circulating electrical currents within material. Type-II superconductors have critical magnetic fields and critical temperatures greater than type-I superconductors.

  2. Teddy Bear Line-Up

    NSDL National Science Digital Library

    This problem requires children to develop logical reasoning and promotes using visualization to plan ahead. Students are presented with a line of four blue, then four red followed by four yellow and finally four green bears and are asked to rearrange them using the least number of moves so that no two bears of the same color are next to each other. The Teachers' Notes page offers rationale, suggestions for implementation, discussion questions, and an idea for support and extension.

  3. Designing Rolling-Element Bearings

    NASA Technical Reports Server (NTRS)

    Moore, James D., Jr.

    2007-01-01

    Bearing Analysis Tool (BAT) is a computer program for designing rolling-element bearings for cryogenic turbomachines. BAT provides a graphical user interface (GUI) that guides the entry of data to develop mathematical models of bearings. The GUI breaks model data into logical subsets that are entered through logic-driven input screens. The software generates a threedimensional graphical model of a bearing as the data are entered. Most dataentry errors become immediately obvious in the graphical model. BAT provides for storage of all the data on a shaft/bearing system, enabling the creation of a library of proven designs. Data from the library can be transferred to subsequent projects by use of simple cut-and-paste routines. BAT includes a library of temperature- dependent cryogenic bearing-material properties for use in the mathematical models. BAT implements algorithms that (1) enable the user to select combinations of design and/or operating-condition parameters, and then (2) automatically optimize the design by performing trade studies over all of the parameter combinations. This feature enables optimization over a large trade space in a fraction of the time taken when using prior bearingmodel software.

  4. Highly active, low-valence molybdenum- and tungsten-amide catalysts for bifunctional imine-hydrogenation reactions.

    PubMed

    Chakraborty, Subrata; Blacque, Olivier; Fox, Thomas; Berke, Heinz

    2014-01-01

    The reactions of [M(NO)(CO)4(ClAlCl3)] (M=Mo, W) with (iPr2PCH2CH2)2NH, (PN(H)P) at 90 °C afforded [M(NO)(CO)(PN(H)P)Cl] complexes (M=Mo, 1a; W, 1b). The treatment of compound 1a with KOtBu as a base at room temperature yielded the alkoxide complex [Mo(NO)(CO)(PN(H)P)(OtBu)] (2a). In contrast, with the amide base Na[N(SiMe3 )2 ], the PN(H) P ligand moieties in compounds 1a and 1b could be deprotonated at room temperature, thereby inducing dehydrochlorination into amido complexes [M(NO)(CO)(PNP)] (M=Mo, 3a; W, 3b; PNP=(iPr2PCH2CH2)2N)). Compounds 3a and 3b have pseudo-trigonal-bipyramidal geometries, in which the amido nitrogen atom is in the equatorial plane. At room temperature, compounds 3a and 3b were capable of adding dihydrogen, with heterolytic splitting, thereby forming pairs of isomeric amine-hydride complexes [Mo(NO)(CO)H(PN(H)P)] (4a(cis) and 4a(trans)) and [W(NO)(CO)H(PN(H)P)] (4b(cis) and 4b(trans); cis and trans correspond to the position of the H and NO groups). H2 approaches the Mo/W=N bond in compounds 3a,b from either the CO-ligand side or from the NO-ligand side. Compounds 4a(cis) and 4a(trans) were only found to be stable under a H2 atmosphere and could not be isolated. At 140 °C and 60 bar H2 , compounds 3a and 3b catalyzed the hydrogenation of imines, thereby showing maximum turnover frequencies (TOFs) of 2912 and 1120 h(-1), respectively, for the hydrogenation of N-(4-methoxybenzylidene)aniline. A Hammett plot for various para-substituted imines revealed linear correlations with a negative slope of -3.69 for para substitution on the benzylidene side and a positive slope of 0.68 for para substitution on the aniline side. Kinetics analysis revealed the initial rate of the hydrogenation reactions to be first order in c(cat.) and zeroth order in c(imine). Deuterium kinetic isotope effect (DKIE) experiments furnished a low kH /kD value (1.28), which supported a Noyori-type metal-ligand bifunctional mechanism with H2 addition as the rate-limiting step. PMID:24129970

  5. The HtrA/DegP family protease MamE is a bifunctional protein with roles in magnetosome protein localization and magnetite biomineralization

    PubMed Central

    Quinlan, Anna; Murat, Dorothée; Vali, Hojatollah; Komeili, Arash

    2011-01-01

    Summary Magnetotactic bacteria contain nanometer-sized, membrane-bound organelles, called magnetosomes, which are tasked with the biomineralization of small crystals of the iron oxide magnetite allowing the organism to use geomagnetic field lines for navigation. A key player in this process is the HtrA/DegP family protease MamE. In its absence, Magnetospirillum magneticum str AMB-1 is able to form magnetosome membranes but not magnetite crystals, a defect previously linked to the mislocalization of magnetosome proteins. In this work we use a directed genetic approach to find that MamE, and another predicted magnetosome-associated protease, MamO, likely function as proteases in vivo. However, as opposed to the complete loss of mamE where no biomineralization is observed, the protease-deficient variant of this protein still supports the initiation and formation of small, 20 nm-sized crystals of magnetite, too small to hold a permanent magnetic dipole moment. This analysis also reveals that MamE is a bifunctional protein with a protease-independent role in magnetosome protein localization and a protease-dependent role in maturation of small magnetite crystals. Together these results imply the existence of a previously unrecognized “checkpoint” in biomineralization where MamE moderates the completion of magnetite formation and thus committal to magneto-aerotaxis as the organism’s dominant mode of navigating the environment. PMID:21414040

  6. MnCo2 O4 Nanowires Anchored on Reduced Graphene Oxide Sheets as Effective Bifunctional Catalysts for Li-O2 Battery Cathodes.

    PubMed

    Kim, Jong Guk; Kim, Youngmin; Noh, Yuseong; Kim, Won Bae

    2015-05-22

    A hybrid composite system of MnCo2 O4 nanowires (MCO NWs) anchored on reduced graphene oxide (RGO) nanosheets was prepared as the bifunctional catalyst of a Li-O2 battery cathode. The catalysts can be obtained from the hybridization of one-dimensional MCO NWs and two-dimensional RGO nanosheets. As O2 -cathode catalysts for Li-O2 cells, the MCO@RGO composites showed a high initial discharge capacity (ca. 11092.1?mAh?gcarbon (-1) ) with a high rate performance. The Li-O2 cells could run for more than 35?cycles with high reversibility under a limited specific capacity of 1000?mAh?gcarbon (-1) with a low potential polarization of 1.36?V, as compared with those of pure Ketjenblack and MCO NWs. The high cycling stability, low potential polarization, and rate capability suggest that the MCO@RGO composites prepared here are promising catalyst candidates for highly reversible Li-O2 battery cathodes. PMID:25908219

  7. Ball Bearings Equipped for In Situ Lubrication on Demand

    NASA Technical Reports Server (NTRS)

    Marchetti, Mario; Jones, William R., Jr.; Pepper, Stephen V.; Jansen, Mark; Predmore, Roamer

    2005-01-01

    In situ systems that provide fresh lubricants to ball/race contacts on demand have been developed to prolong the operational lives of ball bearings. These systems were originally intended to be incorporated into ball bearings in mechanisms that are required to operate in outer space for years, in conditions in which lubricants tend to deteriorate and/or evaporate. These systems may also be useful for similarly prolonging bearing lifetimes on Earth. Reservoirs have been among the means used previously to resupply lubricants. Lubricant- resupply reservoirs are bulky and add complexity to bearing assemblies. In addition, such a reservoir cannot be turned on or off as needed: it supplies lubricant continuously, often leading to an excess of lubricant in the bearing. A lubricator of the present type includes a porous ring cartridge attached to the inner or the outer ring of a ball bearing (see Figure 1). Oil is stored in the porous cartridge and is released by heating the cartridge: Because the thermal expansion of the oil exceeds that of the cartridge, heating causes the ejection of some oil. A metal film can be deposited on a face of the cartridge to serve as an electrical-resistance heater. The heater can be activated in response to a measured increase in torque that signals depletion of oil from the bearing/race contacts. Because the oil has low surface tension and readily wets the bearing-ring material, it spreads over the bearing ring and eventually reaches the ball/race contacts. The Marangoni effect (a surface-tension gradient associated with a temperature gradient) is utilized to enhance the desired transfer of lubricant to the ball/race contacts during heating. For a test, a ball bearing designed for use at low speed was assembled without lubricant and equipped with a porous-ring lubricator, the resistance heater of which consumed a power of less than 1 W when triggered on by a torque-measuring device. In the test, a load of 20 lb (.89 N) was applied and the bearing was turned at a rate of 200 RPM. The lubricator control was turned on at the beginning of the test, turned off for about 800 seconds, then turned on again. As shown in Figure 2, the controlled lubricator stabilized the torque in a low range, starting immediately after initial turn-on and immediately after resumption of the lubricator control.

  8. Hydrostatic bearings for a turbine fluid flow metering device

    DOEpatents

    Fincke, James R. (Rigby, ID)

    1982-01-01

    A rotor assembly fluid metering device has been improved by development of a hydrostatic bearing fluid system which provides bearing fluid at a common pressure to rotor assembly bearing surfaces. The bearing fluid distribution system produces a uniform film of fluid between bearing surfaces and allows rapid replacement of bearing fluid between bearing surfaces, thereby minimizing bearing wear and corrosion.

  9. Hydrostatic bearings for a turbine fluid flow metering device

    DOEpatents

    Fincke, J.R.

    1982-05-04

    A rotor assembly fluid metering device has been improved by development of a hydrostatic bearing fluid system which provides bearing fluid at a common pressure to rotor assembly bearing surfaces. The bearing fluid distribution system produces a uniform film of fluid between bearing surfaces and allows rapid replacement of bearing fluid between bearing surfaces, thereby minimizing bearing wear and corrosion. 3 figs.

  10. Roller bearings for I. C. engines

    Microsoft Academic Search

    M. Mc Kenzie; R. Lugosi

    1987-01-01

    Analyses indicate that lower heat generation, smaller friction coefficients, and thinner lubricant films will occur if roller bearings replace today's journal bearings. Results indicate that, for the conditions selected, the roller bearing operates at a lower coefficient of friction and exhibits less heat generation than the journal bearing. These benefits can conceivably be translated into significantly better cold start characteristics,

  11. Damping Seals And Bearings For A Turbomachine

    NASA Technical Reports Server (NTRS)

    Von Pragenau, George L.

    1990-01-01

    Improved design for support of rotor in turbopump integrates ball bearings with damping seals and damping bearings. Reduces radial (side) loads on ball bearings, making it possible to increase contact angles to withstand increased transient axial loads. Service lives of bearings prolonged.

  12. Customized Wavelet for Bearing Defect Detection

    Microsoft Academic Search

    Brian T. Holm-Hansen; Robert X. Gao; ASME Mem

    2004-01-01

    Rolling element bearings play a critical role in dynamic sys- tems, ranging from paper mills to aircrafts, and unexpected bear- ing failures may result in significant economic losses, even loss of lives. The significance of maintaining effective and safe bearing operations has led to the development of a wide range of bearing condition monitoring and diagnostic techniques over the past

  13. Magnetic Bearing Sets for a Flywheel System

    Microsoft Academic Search

    Guilherme Goncalves Sotelo; R. de Andrade; A. C. Ferreira

    2007-01-01

    This paper presents a magnetic bearing set developed to work in a flywheel energy storage system. The bearing set is composed of a permanent magnetic bearing (PMB) and a superconducting magnetic bearing (SMB). A new configuration of a PMB having Nd-Fe-B magnet rings and a back yoke is proposed and compared with an existing one. Finite element method (FEM) simulations

  14. Comparing kinetic profiles between bifunctional and binary type of Zn(salen)-based catalysts for organic carbonate formation

    PubMed Central

    Martín, Carmen

    2014-01-01

    Summary Zn(salen) complexes have been employed as active catalysts for the formation of cyclic carbonates from epoxides and CO2. A series of kinetic experiments was carried out to obtain information about the mechanism for this process catalyzed by these complexes and in particular about the order-dependence in catalyst. A comparative analysis was done between the binary catalyst system Zn(salphen)/NBu4I and a bifunctional system Zn(salpyr)·MeI with a built-in nucleophile. The latter system demonstrates an apparent second-order dependence on the bifunctional catalyst concentration and thus follows a different, bimetallic mechanism as opposed to the binary catalyst that is connected with a first-order dependence on the catalyst concentration and a monometallic mechanism. PMID:25161742

  15. Dynamics of tropomyosin in muscle fibers as monitored by saturation transfer EPR of bi-functional probe.

    PubMed

    Rayes, Roni F; Kálai, Tamás; Hideg, Kálmán; Geeves, Michael A; Fajer, Piotr G

    2011-01-01

    The dynamics of four regions of tropomyosin was assessed using saturation transfer electron paramagnetic resonance in the muscle fiber. In order to fully immobilize the spin probe on the surface of tropomyosin, a bi-functional spin label was attached to i,i+4 positions via cysteine mutagenesis. The dynamics of bi-functionally labeled tropomyosin mutants decreased by three orders of magnitude when reconstituted into "ghost muscle fibers". The rates of motion varied along the length of tropomyosin with the C-terminus position 268/272 being one order of magnitude slower then N-terminal domain or the center of the molecule. Introduction of troponin decreases the dynamics of all four sites in the muscle fiber, but there was no significant effect upon addition of calcium or myosin subfragment-1. PMID:21701580

  16. Dynamics of Tropomyosin in Muscle Fibers as Monitored by Saturation Transfer EPR of Bi-Functional Probe

    PubMed Central

    Rayes, Roni F.; Kálai, Tamás; Hideg, Kálmán; Geeves, Michael A.; Fajer, Piotr G.

    2011-01-01

    The dynamics of four regions of tropomyosin was assessed using saturation transfer electron paramagnetic resonance in the muscle fiber. In order to fully immobilize the spin probe on the surface of tropomyosin, a bi-functional spin label was attached to i,i+4 positions via cysteine mutagenesis. The dynamics of bi-functionally labeled tropomyosin mutants decreased by three orders of magnitude when reconstituted into “ghost muscle fibers”. The rates of motion varied along the length of tropomyosin with the C-terminus position 268/272 being one order of magnitude slower then N-terminal domain or the center of the molecule. Introduction of troponin decreases the dynamics of all four sites in the muscle fiber, but there was no significant effect upon addition of calcium or myosin subfragment-1. PMID:21701580

  17. Designing bifunctional NOP receptor-mu opioid receptor ligands from NOP-receptor selective scaffolds. Part II

    PubMed Central

    Journigan, V. Blair; Polgar, Willma; Khroyan, Taline V.; Zaveri, Nurulain T.

    2014-01-01

    The nociceptin opioid receptor (NOP) and its endogenous peptide ligand nociceptin/orphanin FQ have been shown to modulate the pharmacological effects of the classical opioid receptor system. Suppression of opioid-induced reward associated with mu-opioid receptor (MOP)-mediated analgesia, without decreasing anti-nociceptive efficacy, can potentially be achieved with NOP agonists having bifunctional agonist activity at MOP, to afford ‘non-addicting’ analgesics. In Part II of this series, we describe a continuing structure-activity relationship (SAR) study of the NOP-selective piperidin-4-yl-1,3-dihydroindol-2-one scaffold, to obtain bifunctional activity at MOP, and a suitable ratio of NOP/MOP agonist activity that produces a non-addicting analgesic profile. The SAR reported here is focused on the influence of various piperidine nitrogen aromatic substituents on the ratio of binding affinity and intrinsic activity at both the NOP and MOP receptors. PMID:24657054

  18. Vertically integrated translational studies of PDX1 as a therapeutic target for pancreatic cancer via a novel bifunctional RNAi platform.

    PubMed

    Wu, J; Liu, S; Yu, J; Zhou, G; Rao, D; Jay, C M; Kumar, P; Sanchez, R; Templeton, N; Senzer, N; Maples, P; Nemunaitis, J; Brunicardi, F C

    2014-02-01

    RNA interference (RNAi) represents a powerful, new tool for scientific investigation as well as a promising new form of targeted gene therapy, with applications currently in clinical trials. Bifunctional short hairpin RNA (shRNA) are synthetic RNAi molecules, engineered to utilize multiple endogenous RNAi pathways to specifically silence target genes. Pancreatic and duodenal homeobox 1 (PDX1) is a key regulator of pancreatic development, ?-cell differentiation, normal ?-cell function and pancreatic cancer. Our aim is to review the process of identifying PDX1 as a specific, potential RNAi target in pancreatic cancer, as well as the underlying mechanisms and various forms of RNAi, with subsequent testing and development of PDX1-targeted bifunctional shRNA therapy. PMID:24457987

  19. Space Shuttle Body Flap Actuator Bearing Testing for NASA Return to Flight

    NASA Technical Reports Server (NTRS)

    Jett, Timothy R.; Predmore, Roamer E.; Dube, Michael J.; Jones, William R., Jr.

    2006-01-01

    The Space Shuttle body flap is located beneath the main engine nozzles and is required for proper aerodynamic control during orbital descent. Routine inspection of one of four body flap actuators found one of the actuator bearings had degraded and blackened balls. A test program was initiated to demonstrate that it is acceptable to operate bearings which are degraded from operation over several flights. This test exposed the bearing to predicted flight axial loads, speeds and temperatures. Testing at 140 F has been completed, and results indicate the previously flown bearings are acceptable for up to 12 additional missions. Additional testing is underway to determine the lubricant life at various temperatures and stresses and to further understand the mechanism that caused the blacken balls. Initial results of this testing indicates that bearing life is shorten at room temperature possibly due fact that higher temperature (140 F) accelerates the flow of grease and oil into the wear surface

  20. Optico-cochleo-dentate degeneration associated with severe peripheral neuropathy and caused by peroxisomal D-bifunctional protein deficiency

    Microsoft Academic Search

    J. M. Schröder; V. Hackel; R. J. A. Wanders; G. Göhlich-Ratmann; T. Voit

    2004-01-01

    The clinical, neuroradiological, neuropathological and biochemical findings in a patient with optico-cochleo-dentate degeneration (OCDD; OMIM 258700) are presented in a severe case succumbing at the age of 4 years. The electron microscopic and biochemical data showed for the first time that OCDD may occur as the phenotypic expression of D-bifunctional protein deficiency, i.e., a peroxisomal disorder. The boy was born as

  1. Enhanced uptake of porous silica microparticles by bifunctional surface modification with a targeting antibody and a biocompatible polymer.

    PubMed

    Cheng, Kai; Blumen, Steven R; MacPherson, Maximilian B; Steinbacher, Jeremy L; Mossman, Brooke T; Landry, Christopher C

    2010-09-01

    Strategies were developed by which mesoporous microparticles were modified on their external surfaces with tetraethylene glycol (TEG), a protein, or both, leaving the pore surfaces available for modification with a separate moiety, such as a dye. Only particles bifunctionally modified with both TEG and a cell-specific antibody were taken up specifically by a targeted cancer cell line. In contrast to similarly functionalized nanoparticles, endocytosed microparticles were not contained within a lysosome. PMID:20707315

  2. Enhanced Uptake of Porous Silica Microparticles by Bifunctional Surface Modification with a Targeting Antibody and a Biocompatible Polymer

    PubMed Central

    Cheng, Kai; Blumen, Steven R.; MacPherson, Maximilian B.; Steinbacher, Jeremy L.; Mossman, Brooke T.; Landry, Christopher C.

    2010-01-01

    Strategies were developed by which mesoporous microparticles were modified on their external surfaces with tetraethylene glycol (TEG), a protein, or both, leaving the pore surfaces available for modification with a separate moiety, such as a dye. Only particles bifunctionally modified with both TEG and a cell-specific antibody were taken up specifically by a targeted cancer cell line. In contrast to similarly functionalized nanoparticles, endocytosed microparticles were not contained within a lysosome. PMID:20707315

  3. Highly enantioselective synthesis of 1,3-mercapto alcohols from ?,?-unsaturated ketones: asymmetric bifunctional group exchange reaction

    Microsoft Academic Search

    Hiroaki Shiraki; Kiyoharu Nishide; Manabu Node

    2000-01-01

    Optically active 1,3-mercapto alcohols were synthesized from ?,?-unsaturated ketones using a chiral reagent B and dimethylaluminum chloride in two steps. The transformation involved a tandem Michael addition–MPV reduction and a base-catalyzed elimination. The two newly created chiral carbons in trans-chalcone derivatives were enantioselectively controlled to a high degree. Using the above transformation, an asymmetric bifunctional group exchange reaction between the

  4. A Bifunctional Enzyme (Delta^1Pyrroline5Carboxylate Synthetase) Catalyzes the First Two Steps in Proline Biosynthesis in Plants

    Microsoft Academic Search

    Chien-An A. Hu; Ashton J. Delauney; Desh Pal S. Verma

    1992-01-01

    Many plants synthesize and accumulate proline in response to osmotic stress. Despite the importance of this pathway, however, the exact metabolic route and enzymes involved in the synthesis of proline in plants have not been unequivocally identified. We report here the isolation of a mothbean (Vigna aconitifolia) cDNA clone encoding a bifunctional enzyme, Delta^1-pyrroline-5-carboxylate synthetase (P5CS), with both gamma-glutamyl kinase

  5. Bifunctional TiO2 Catalysts for Efficient Cr(VI) Photoreduction Under Solar Light Irradiation Without Addition of Acids

    NASA Astrophysics Data System (ADS)

    Shi, Fu-cheng; Wang, Wen-dong; Huang, Wei-xin

    2012-04-01

    Bifunctional TiO2 photocatalysts co-doped with nitrogen and sulfur were prepared by the controlled thermal decomposition of ammonium titanyl sulfate precursor. They have both photocatalytic activity and Brønsted acidity, and thus are active in the photoreduction of Cr(VI) under solar light irradiation without the addition of acids. The activity is superior to that of Degussa P25 in the acidified suspension at the same pH adjusted by H2SO4.

  6. Design and characterization of bi-functional electrocatalytic layers for application in PEM unitized regenerative fuel cells

    Microsoft Academic Search

    S. A. Grigoriev; P. Millet; K. A. Dzhus; H. Middleton; T. O. Saetre; V. N. Fateev

    2010-01-01

    Results concerning the development and characterization of bi-functional electrocatalytic layers for application in unitized regenerative fuel cells (URFCs) based on proton exchange membrane (PEM) technology are reported. Carbon-supported hydrophobic (10wt.% of PTFE) Pt catalysts (40wt.% of Pt), and Pt and Ir black powders of large specific areas have been synthesized. Their structure, morphology and electrochemical properties have been investigated using

  7. Double coating via repeat admicellar polymerization for preparation of bifunctional cotton fabric: Ultraviolet protection and water repellence

    Microsoft Academic Search

    Suchada Tragoonwichian; Edgar A. O’Rear; Nantaya Yanumet

    2009-01-01

    Bifunctional cotton fabric was produced by double coating via repeat admicellar polymerization using dodecylbenzenesulfonic acid, sodium salt (DBSA), as the surfactant. 2-Hydroxy-4-acryloyloxybenzophenone (HAB) was first coated on a cotton fabric in order to improve its ultraviolet protection and then methacryloxymethyltrimethylsilane (MSi) was coated to create a water-repellent surface. Adsorption of DBSA on the HAB-coated substrate was found to be less

  8. Isomerization and Hydrocracking of Heptane over Bimetallic Bifunctional PtPd\\/H-Beta and PtPd\\/USY Zeolite Catalysts

    Microsoft Academic Search

    E. Blomsma; J. A. Martens; P. A. Jacobs

    1997-01-01

    Bifunctional catalysts are prepared by loading NH4-Beta zeolites with platinum, palladium, and platinum–palladium metal combinations via cation exchange and incipient wetness impregnation with Pt(NH3)4Cl2and Pd(NH3)4Cl2complexes, followed by calcination and reduction. In comparison to the Pt and Pd loaded acid zeolites, the bimetallic Pd–Pt zeolites are found to be more active and selective in the isomerization of heptane. The noble metal

  9. Control of charge trapping in a novel photorefractive composite consisting of a bifunctional molecule based on TPD

    Microsoft Academic Search

    Henk J. Bolink; C. Arts; Victor V. Krasnikov; George G. Malliaras; Georges Hadziioannou

    1996-01-01

    A novel photorefractive polymer is presented, based on a bifunctional molecule which is a derivative of the well known charge transport molecule N,N'-diphenyl-N,N'-bis(3- methylphenyl)-[1,1'-biphenyl]-4,4'-diamine (TPD). In this material the low intrinsic tap density causes the rather low value for the gain coefficient as well as the 90 degree phase shift between the refractive index grating and the illumination pattern. The

  10. Voltammetric determination of Cd 2+ based on the bifunctionality of single-walled carbon nanotubes–Nafion film

    Microsoft Academic Search

    Dong Sun; Xiafeng Xie; Yuepiao Cai; Huajie Zhang; Kangbing Wu

    2007-01-01

    In the presence of Nafion, single-walled carbon nanotubes (SWNTs) were easily dispersed into ethanol, resulting in a homogeneous SWNTs\\/Nafion suspension. After evaporating ethanol, a SWNTs\\/Nafion film with bifunctionality was constructed onto glassy carbon electrode (GCE) surface. Attributing to the strong cation-exchange ability of Nafion and excellent properties of SWNTs, the SWNTs\\/Nafion film-coated GCE remarkably enhances the sensitivity of determination of

  11. High performance lithium-ion hybrid capacitors with pre-lithiated hard carbon anodes and bifunctional cathode electrodes

    NASA Astrophysics Data System (ADS)

    Sun, Xianzhong; Zhang, Xiong; Zhang, Haitao; Xu, Nansheng; Wang, Kai; Ma, Yanwei

    2014-12-01

    Lithium-ion hybrid capacitor is a type of energy storage device that bridge the gap between lithium-ion battery and electrical double layer capacitor. We have developed a facile approach to achieve the pre-lithiation of carbonaceous anode, and then fabricated lithium-ion hybrid capacitors with bifunctional cathode containing capacitor material (activated carbon) and battery material (LiNi0.5Co0.2Mn0.3O2). The hybrid capacitor with 25 wt.% LiNi0.5Co0.2Mn0.3O2 addition in bifunctional cathode (denoted as LAN25) exhibits excellent rate capability and high energy density. The rate capability of LAN25 is comparable to that with pure AC cathode (denoted as LAC), while the volumetric energy density is 1.36 times higher than the latter one. The continuous galvanostatic charge-discharge cycling tests reveal that the lithium-ion hybrid capacitor remains more than 98% capacity after 20,000 cycles, and nearly 100% coulombic efficiency over entire cycles. The superior performance is ascribed to the synergy effect of the active components in bifunctional cathode and the effective pre-lithiation of hard carbon anode. The present work makes the study of lithium-ion hybrid capacitor easily accessible and broadens roads to hybrid devices with high energy density, high power density and long cycle life.

  12. Biological and Conformational Evaluation of Bifunctional Compounds for Opioid Receptor Agonists and Neurokinin 1 Receptor Antagonists Possessing Two Penicillamines

    PubMed Central

    Yamamoto, Takashi; Nair, Padma; Jacobsen, Neil E.; Kulkarni, Vinod; Davis, Peg; Ma, Shou-wu; Navratilova, Edita; Yamamura, Henry I.; Vanderah, Todd W.; Porreca, Frank; Lai, Josephine; Hruby, Victor J.

    2010-01-01

    Neuropathic pain states and tolerance to opioids can result from system changes in the CNS, such as up-regulation of the NK1 receptor and substance P, which have anti-opioid effects in ascending or descending pain-signaling pathways. Bifunctional compounds, possessing both the NK1 antagonist pharmacophore and the opioid agonist pharmacophore with delta-selectivity, could counteract these system changes to have significant analgesic efficacy without undesirable side effects. As a result of the introduction of cyclic and topological constraints with penicillamines, 2 (Tyr-cyclo[D-Pen-Gly-Phe-Pen]-Pro-Leu-Trp-NH-[3?,5?-(CF3)2-Bzl]) was found as the best bifunctional compound with effective NK1 antagonist and potent opioid agonist activities, and 1400-fold delta-selectivity over the mu-receptor. The NMR structural analysis of 2 revealed that the relative positioning of the two connected pharmacophores as well as its cyclic and topological constraints might be responsible for its excellent bifunctional activities as well as its significant delta-opioid selectivity. Together with the observed high metabolic stability, 2 could be considered as a valuable research tool and possibly a promising candidate for a novel analgesic drug. PMID:20617791

  13. Superconductor bearings, flywheels and transportation

    NASA Astrophysics Data System (ADS)

    Werfel, F. N.; Floegel-Delor, U.; Rothfeld, R.; Riedel, T.; Goebel, B.; Wippich, D.; Schirrmeister, P.

    2012-01-01

    This paper describes the present status of high temperature superconductors (HTS) and of bulk superconducting magnet devices, their use in bearings, in flywheel energy storage systems (FESS) and linear transport magnetic levitation (Maglev) systems. We report and review the concepts of multi-seeded REBCO bulk superconductor fabrication. The multi-grain bulks increase the averaged trapped magnetic flux density up to 40% compared to single-grain assembly in large-scale applications. HTS magnetic bearings with permanent magnet (PM) excitation were studied and scaled up to maximum forces of 10 kN axially and 4.5 kN radially. We examine the technology of the high-gradient magnetic bearing concept and verify it experimentally. A large HTS bearing is tested for stabilizing a 600 kg rotor of a 5 kWh/250 kW flywheel system. The flywheel rotor tests show the requirement for additional damping. Our compact flywheel system is compared with similar HTS-FESS projects. A small-scale compact YBCO bearing with in situ Stirling cryocooler is constructed and investigated for mobile applications. Next we show a successfully developed modular linear Maglev system for magnetic train operation. Each module levitates 0.25t at 10 mm distance during one-day operation without refilling LN2. More than 30 vacuum cryostats containing multi-seeded YBCO blocks are fabricated and are tested now in Germany, China and Brazil.

  14. 'Dodo' and 'Baby Bear' Trenches

    NASA Technical Reports Server (NTRS)

    2008-01-01

    NASA's Phoenix Mars Lander's Surface Stereo Imager took this image on Sol 11 (June 5, 2008), the eleventh day after landing. It shows the trenches dug by Phoenix's Robotic Arm. The trench on the left is informally called 'Dodo' and was dug as a test. The trench on the right is informally called 'Baby Bear.' The sample dug from Baby Bear will be delivered to the Phoenix's Thermal and Evolved-Gas Analyzer, or TEGA. The Baby Bear trench is 9 centimeters (3.1 inches) wide and 4 centimeters (1.6 inches) deep.

    The Phoenix Mission is led by the University of Arizona, Tucson, on behalf of NASA. Project management of the mission is by NASA's Jet Propulsion Laboratory, Pasadena, Calif. Spacecraft development is by Lockheed Martin Space Systems, Denver.

  15. The Mycobacterium tuberculosis Rv2540c DNA sequence encodes a bifunctional chorismate synthase

    PubMed Central

    Ely, Fernanda; Nunes, José ES; Schroeder, Evelyn K; Frazzon, Jeverson; Palma, Mário S; Santos, Diógenes S; Basso, Luiz A

    2008-01-01

    Background The emergence of multi- and extensively-drug resistant Mycobacterium tuberculosis strains has created an urgent need for new agents to treat tuberculosis (TB). The enzymes of shikimate pathway are attractive targets to the development of antitubercular agents because it is essential for M. tuberculosis and is absent from humans. Chorismate synthase (CS) is the seventh enzyme of this route and catalyzes the NADH- and FMN-dependent synthesis of chorismate, a precursor of aromatic amino acids, naphthoquinones, menaquinones, and mycobactins. Although the M. tuberculosis Rv2540c (aroF) sequence has been annotated to encode a chorismate synthase, there has been no report on its correct assignment and functional characterization of its protein product. Results In the present work, we describe DNA amplification of aroF-encoded CS from M. tuberculosis (MtCS), molecular cloning, protein expression, and purification to homogeneity. N-terminal amino acid sequencing, mass spectrometry and gel filtration chromatography were employed to determine identity, subunit molecular weight and oligomeric state in solution of homogeneous recombinant MtCS. The bifunctionality of MtCS was determined by measurements of both chorismate synthase and NADH:FMN oxidoreductase activities. The flavin reductase activity was characterized, showing the existence of a complex between FMNox and MtCS. FMNox and NADH equilibrium binding was measured. Primary deuterium, solvent and multiple kinetic isotope effects are described and suggest distinct steps for hydride and proton transfers, with the former being more rate-limiting. Conclusion This is the first report showing that a bacterial CS is bifunctional. Primary deuterium kinetic isotope effects show that C4-proS hydrogen is being transferred during the reduction of FMNox by NADH and that hydride transfer contributes significantly to the rate-limiting step of FMN reduction reaction. Solvent kinetic isotope effects and proton inventory results indicate that proton transfer from solvent partially limits the rate of FMN reduction and that a single proton transfer gives rise to the observed solvent isotope effect. Multiple isotope effects suggest a stepwise mechanism for the reduction of FMNox. The results on enzyme kinetics described here provide evidence for the mode of action of MtCS and should thus pave the way for the rational design of antitubercular agents. PMID:18445278

  16. Application of computational fluid dynamics on cavitation in journal bearings

    NASA Astrophysics Data System (ADS)

    Riedel, Marco; Schmidt, Marcus; Reinke, Peter; Nobis, Matthias; Redlich, Marcel

    2014-03-01

    Journal bearings are applied in internal combustion engines due to their favourable wearing quality and operating characteristics. Under certain operating conditions damage of the journal bearing can occur caused by cavitation. The cavitation reduces the load capacity and leads to material erosion. Experimental investigations of cavitating flows in dimension of real journal bearing are difficult to realize or almost impossible caused by the small gap and transient flow conditions. Therefore numerical simulation is a very helpful engineering tool to research the cavitation behaviour. The CFD-Code OpenFOAM is used to analyse the flow field inside the bearing. The numerical cavitation model based on a bubble dynamic approach and requires necessary initial parameter for the calculation, such as nuclei bubble diameter, the number of nuclei and two empirical constants. The first part of this paper shows the influence of these parameters on the solution. For the adjustment of the parameters an experiment of Jakobsson et.al. [1] was used to validate the numerical flow model. The parameters have been varied according to the method Design of Experiments (DoE). With a defined model equation the parameters determined, to identify the parameter for CFD-calculations in comparison to the experimental values. The second part of the paper presents investigations on different geometrical changes in the bearing geometry. The effect of these geometrical changes on cavitation was compared with experimental results from Wollfarth [2] and Garner et.al. [3].

  17. Nonlinear dynamics of attractive magnetic bearings

    NASA Technical Reports Server (NTRS)

    Hebbale, K. V.; Taylor, D. L.

    1987-01-01

    The nonlinear dynamics of a ferromagnetic shaft suspended by the force of attraction of 1, 2, or 4 independent electromagnets is presented. Each model includes a state variable feedback controller which has been designed using the pole placement method. The constitutive relationships for the magnets are derived analytically from magnetic circuit theory, and the effects of induced eddy currents due to the rotation of the journal are included using Maxwell's field relations. A rotor suspended by four electro-magnets with closed loop feedback is shown to have nine equilibrium points within the bearing clearance space. As the rotor spin speed increases, the system is shown to pass through a Hopf bifurcation (a flutter instability). Using center manifold theory, this bifurcation can be shown to be of the subcritical type, indicating an unstable limit cycle below the critical speed. The bearing is very sensitive to initial conditions, and the equilibrium position is easily upset by transient excitation. The results are confirmed by numerical simulation.

  18. Chromizing of ball bearing steels for extending bearing life

    Microsoft Academic Search

    G. N. Dubinin; G. L. Oganesyan; V. P. Zhukov; V. A. Boikov

    1986-01-01

    1.Diffusion chromizing of self-aligning bearings of steels ShKh15 and 95Kh18 enhances wear resistance and corrosion resistance of these steels.2.Diffusion chromizing makes it possible to replace stainless steel 95Kh18 by the relatively cheap steel ShKh15 with better operational properties obtained after chromizing.

  19. BIFUNCTIONAL CATALYSTS FOR THE SELECTIVE CATALYTIC REDUCTION OF NO BY HYDROCARBONS

    SciTech Connect

    Neylon, M; Castagnola, M; Kropf, A.; Marshall, C

    2003-08-24

    Novel bifunctional catalysts combining two active phases, typically Cu-ZSM-5 and a modifier, were prepared and tested for the selective catalytic reduction of nitrogen oxides using propylene in order to overcome the hindering effects of water typically seen for single-phase catalysts such as Cu-ZSM-5. The catalysts were made by typical preparation techniques, but parameters could be varied to influence the catalyst. The physical characterization of the materials showed that the modification phase was added strictly to the external surface of the zeolite without hindering any internal surface area. Chemical characterization by temperature programmed reactions, DRIFTS and x-ray absorption spectroscopy indicated strong interaction between the two phases, primarily producing materials that exhibited lower reduction temperatures. Two improvements in NOx reduction activity (1000 ppm NO, 1000 ppm C3H6, 2% O2, 30,000 hr-1 GHSV) were seen for these catalysts compared with Cu- ZSM-5: a lower temperature of maximum NOx conversion activity (as low at 250 C), and an enhancement of activity when water was present in the system. The use of a second phase provides a way to further tune the properties of the catalyst in order to achieve mechanistic conditions necessary to maximize NOx remediation.

  20. Redirection of genetically engineered CAR-T cells using bifunctional small molecules.

    PubMed

    Kim, Min Soo; Ma, Jennifer S Y; Yun, Hwayoung; Cao, Yu; Kim, Ji Young; Chi, Victor; Wang, Danling; Woods, Ashley; Sherwood, Lance; Caballero, Dawna; Gonzalez, Jose; Schultz, Peter G; Young, Travis S; Kim, Chan Hyuk

    2015-03-01

    Chimeric antigen receptor (CAR)-engineered T cells (CAR-Ts) provide a potent antitumor response and have become a promising treatment option for cancer. However, despite their efficacy, CAR-T cells are associated with significant safety challenges related to the inability to control their activation and expansion and terminate their response. Herein, we demonstrate that a bifunctional small molecule "switch" consisting of folate conjugated to fluorescein isothiocyanate (folate-FITC) can redirect and regulate FITC-specific CAR-T cell activity toward folate receptor (FR)-overexpressing tumor cells. This system was shown to be highly cytotoxic to FR-positive cells with no activity against FR-negative cells, demonstrating the specificity of redirection by folate-FITC. Anti-FITC-CAR-T cell activation and proliferation was strictly dependent on the presence of both folate-FITC and FR-positive cells and was dose titratable with folate-FITC switch. This novel treatment paradigm may ultimately lead to increased safety for CAR-T cell immunotherapy. PMID:25692571

  1. Novel Bifunctional Cyclic Chelator for (89)Zr Labeling-Radiolabeling and Targeting Properties of RGD Conjugates.

    PubMed

    Zhai, Chuangyan; Summer, Dominik; Rangger, Christine; Franssen, Gerben M; Laverman, Peter; Haas, Hubertus; Petrik, Milos; Haubner, Roland; Decristoforo, Clemens

    2015-06-01

    Within the last years (89)Zr has attracted considerable attention as long-lived radionuclide for positron emission tomography (PET) applications. So far desferrioxamine B (DFO) has been mainly used as bifunctional chelating system. Fusarinine C (FSC), having complexing properties comparable to DFO, was expected to be an alternative with potentially higher stability due to its cyclic structure. In this study, as proof of principle, various FSC-RGD conjugates targeting ?vß3 integrins were synthesized using different conjugation strategies and labeled with (89)Zr. In vitro stability, biodistribution, and microPET/CT imaging were evaluated using [(89)Zr]FSC-RGD conjugates or [(89)Zr]triacetylfusarinine C (TAFC). Quantitative (89)Zr labeling was achieved within 90 min at room temperature. The distribution coefficients of the different radioligands indicate hydrophilic character. Compared to [(89)Zr]DFO, [(89)Zr]FSC derivatives showed excellent in vitro stability and resistance against transchelation in phosphate buffered saline (PBS), ethylenediaminetetraacetic acid solution (EDTA), and human serum for up to 7 days. Cell binding studies and biodistribution as well as microPET/CT imaging experiments showed efficient receptor-specific targeting of [(89)Zr]FSC-RGD conjugates. No bone uptake was observed analyzing PET images indicating high in vivo stability. These findings indicate that FSC is a highly promising chelator for the development of (89)Zr-based PET imaging agents. PMID:25941834

  2. Bifunctional nanoparticles for surface-enhanced Raman spectroscopy-based leukemia biomarker detection

    NASA Astrophysics Data System (ADS)

    Mehn, Dora; Morasso, Carlo; Vanna, Renzo; Schiumarini, Domitilla; Bedoni, Marzia; Ciceri, Fabio; Gramatica, Furio

    2014-03-01

    The Wilms tumor gene (WT1) is a biomarker overexpressed in more than 90% of acute myeloid leukemia patients. Fast and sensitive detection of the WT1 in blood samples would allow monitoring of the minimal residual disease during clinical remission and would permit early detection of a potential relapse in acute myeloid leukemia. In this work, Surface Enhanced Raman Spectroscopy (SERS) based detection of the WT1 sequence using bifunctional, magnetic core - gold shell nanoparticles is presented. The classical co-precipitation method was applied to generate magnetic nanoparticles which were coated with a gold shell after modification with aminopropyltriethoxy silane and subsequent deposition of gold nanoparticle seeds. Simple hydroquinone based reduction procedure was applied for the shell growing in water based reaction mixture at room temperature. Thiolated ssDNA probes of the WT1 sequence were immobilized as capture oligonucleotides on the gold surface. Malachite green was applied both for testing the amplification performance of the core-shell colloidal SERS substrate and also as label dye of the target DNA sequence. The SERS enhancer efficacy of the core-shell nanomaterial was compared with the efficacy of classical spherical gold particles produced using the conventional citrate reduction method. The core-shell particles were found not only to provide an opportunity for facile separation in a heterogeneous reaction system but also to be superior regarding robustness as SERS enhancers.

  3. Modifying lysine biosynthesis and catabolism in corn with a single bifunctional expression/silencing transgene cassette.

    PubMed

    Frizzi, Alessandra; Huang, Shihshieh; Gilbertson, Larry A; Armstrong, Toni A; Luethy, Michael H; Malvar, Thomas M

    2008-01-01

    Although it is one of the major crops in the world, corn has poor nutritional quality for human and animal consumption due to its low lysine content. Here, we report a method of simultaneous expression of a deregulated lysine biosynthetic enzyme, CordapA, and reduction of a bifunctional lysine degradation enzyme, lysine-ketoglutarate reductase/saccharophine dehydrogenase (LKR/SDH), in transgenic corn plants by a single transgene cassette. This is accomplished by inserting an inverted-repeat sequence targeting the maize LKR/SDH gene into an intron of a transgene cassette that expresses CordapA. This combination of LKR/SDH silencing and CordapA expression led to the accumulation of free lysine to over 4000 p.p.m. in transgenic corn grain, compared to less than 100 p.p.m. in wild-type controls. This intron-embedded silencing cassette design reduces the number of transgene cassettes needed in transgenic approaches for manipulating metabolic pathways that sometimes require expression of one gene and silencing of another. PMID:17725550

  4. The Golgi localized bifunctional UDP-rhamnose/UDP-galactose transporter family of Arabidopsis.

    PubMed

    Rautengarten, Carsten; Ebert, Berit; Moreno, Ignacio; Temple, Henry; Herter, Thomas; Link, Bruce; Doñas-Cofré, Daniela; Moreno, Adrián; Saéz-Aguayo, Susana; Blanco, Francisca; Mortimer, Jennifer C; Schultink, Alex; Reiter, Wolf-Dieter; Dupree, Paul; Pauly, Markus; Heazlewood, Joshua L; Scheller, Henrik V; Orellana, Ariel

    2014-08-01

    Plant cells are surrounded by a cell wall that plays a key role in plant growth, structural integrity, and defense. The cell wall is a complex and diverse structure that is mainly composed of polysaccharides. The majority of noncellulosic cell wall polysaccharides are produced in the Golgi apparatus from nucleotide sugars that are predominantly synthesized in the cytosol. The transport of these nucleotide sugars from the cytosol into the Golgi lumen is a critical process for cell wall biosynthesis and is mediated by a family of nucleotide sugar transporters (NSTs). Numerous studies have sought to characterize substrate-specific transport by NSTs; however, the availability of certain substrates and a lack of robust methods have proven problematic. Consequently, we have developed a novel approach that combines reconstitution of NSTs into liposomes and the subsequent assessment of nucleotide sugar uptake by mass spectrometry. To address the limitation of substrate availability, we also developed a two-step reaction for the enzymatic synthesis of UDP-l-rhamnose (Rha) by expressing the two active domains of the Arabidopsis UDP-l-Rha synthase. The liposome approach and the newly synthesized substrates were used to analyze a clade of Arabidopsis NSTs, resulting in the identification and characterization of six bifunctional UDP-l-Rha/UDP-d-galactose (Gal) transporters (URGTs). Further analysis of loss-of-function and overexpression plants for two of these URGTs supported their roles in the transport of UDP-l-Rha and UDP-d-Gal for matrix polysaccharide biosynthesis. PMID:25053812

  5. Smoothelin-like 1 Protein Is a Bifunctional Regulator of the Progesterone Receptor during Pregnancy*

    PubMed Central

    Bodoor, Khaldon; Lontay, Beata; Safi, Rachid; Weitzel, Douglas H.; Loiselle, David; Wei, Zhengzheng; Lengyel, Szabolcs; McDonnell, Donald P.; Haystead, Timothy A.

    2011-01-01

    During pregnancy, uterine smooth muscle (USM) coordinately adapts its contractile phenotype in order to accommodate the developing fetus and then prepare for delivery. Herein we show that SMTNL1 plays a major role in pregnancy to promote adaptive responses in USM and that this process is specifically mediated through interactions of SMTNL1 with the steroid hormone receptor PR-B. In vitro and in vivo SMTNL1 selectively binds PR and not other steroid hormone receptors. The physiological relationship between the two proteins was also established in global gene expression and transcriptional reporter studies in pregnant smtnl1?/? mice and by RNA interference in progesterone-sensitive cell lines. We show that the contraction-associated and progestin-sensitive genes (oxytocin receptor, connexin 43, and cyclooxygenase-2) and prolactins are down-regulated in pregnant smtnl1?/? mice. We suggest that SMTNL1 is a bifunctional co-regulator of PR-B signaling and thus provides a molecular mechanism whereby PR-B is targeted to alter gene expression patterns within USM cells to coordinately promote alterations in USM function during pregnancy. PMID:21771785

  6. Purification and characterisation of a bifunctional alginate lyase from novel Isoptericola halotolerans CGMCC 5336.

    PubMed

    Dou, Wenfang; Wei, Dan; Li, Hui; Li, Heng; Rahman, Muhammad Masfiqur; Shi, Jinsong; Xu, Zhenghong; Ma, Yanhe

    2013-11-01

    A novel halophilic alginate-degrading microorganism was isolated from rotten seaweed and identified as Isoptericola halotolerans CGMCC5336. The lyase from the strain was purified to homogeneity by combining of ammonium sulfate fractionation and anion-exchange chromatography with a specific activity of 8409.19 U/ml and a recovery of 25.07%. This enzyme was a monomer with a molecular mass of approximately 28 kDa. The optimal temperature and pH were 50 °C and pH 7.0, respectively. The lyase maintained stability at neutral pH (7.0-8.0) and temperatures below 50 °C. Metal ions including Na(+), Mg(2+), Mn(2+), and Ca(2+) notably increased the activity of the enzyme. With sodium alginate as the substrate, the Km and Vmax were 0.26 mg/ml and 1.31 mg/ml min, respectively. The alginate lyase had substrate specificity for polyguluronate and polymannuronate units in alginate molecules, indicating its bifunctionality. These excellent characteristics demonstrated the potential applications in alginate oligosaccharides production with low polymerisation degrees. PMID:24053829

  7. Reflex assessment of a reciprocal inhibition between bifunctional ago-antagonist muscles.

    PubMed

    Pérot, C; Mora, I; Goubel, F

    1994-01-01

    Neuronal connections between the peroneus longus and the soleus, ago-antagonist bifunctional muscles, were investigated by reflex analysis. The peroneus longus H-reflex, obtained by stimulating the common peroneal nerve, was conditioned by a posterior tibial nerve stimulation. This conditioning stimulus induced an early inhibition of the peroneus longus H-reflex and the degree of inhibition increased with the conditioning stimulus intensity. The soleus H-reflex, solicited by stimulating the posterior tibial nerve, was conditioned by passive adduction movements. These movements were passive quick-release movements achieved by a specific device containing an electromagnet and stiff springs. The passive adduction movement induced both a myotatic reflex in the stretched muscles and an early inhibition of the test soleus H-reflex. This inhibition is most likely due to the activation of the primary spindle afferents of the stretched muscles. Thus we propose an antagonist neuronal scheme between peroneus longus and soleus muscles in spite of their agonism in plantarflexion. PMID:20870550

  8. Novel Bifunctional Cyclic Chelator for 89Zr Labeling–Radiolabeling and Targeting Properties of RGD Conjugates

    PubMed Central

    2015-01-01

    Within the last years 89Zr has attracted considerable attention as long-lived radionuclide for positron emission tomography (PET) applications. So far desferrioxamine B (DFO) has been mainly used as bifunctional chelating system. Fusarinine C (FSC), having complexing properties comparable to DFO, was expected to be an alternative with potentially higher stability due to its cyclic structure. In this study, as proof of principle, various FSC-RGD conjugates targeting ?vß3 integrins were synthesized using different conjugation strategies and labeled with 89Zr. In vitro stability, biodistribution, and microPET/CT imaging were evaluated using [89Zr]FSC-RGD conjugates or [89Zr]triacetylfusarinine C (TAFC). Quantitative 89Zr labeling was achieved within 90 min at room temperature. The distribution coefficients of the different radioligands indicate hydrophilic character. Compared to [89Zr]DFO, [89Zr]FSC derivatives showed excellent in vitro stability and resistance against transchelation in phosphate buffered saline (PBS), ethylenediaminetetraacetic acid solution (EDTA), and human serum for up to 7 days. Cell binding studies and biodistribution as well as microPET/CT imaging experiments showed efficient receptor-specific targeting of [89Zr]FSC-RGD conjugates. No bone uptake was observed analyzing PET images indicating high in vivo stability. These findings indicate that FSC is a highly promising chelator for the development of 89Zr-based PET imaging agents. PMID:25941834

  9. The Golgi localized bifunctional UDP-rhamnose/UDP-galactose transporter family of Arabidopsis

    PubMed Central

    Rautengarten, Carsten; Ebert, Berit; Moreno, Ignacio; Temple, Henry; Herter, Thomas; Link, Bruce; Doñas-Cofré, Daniela; Moreno, Adrián; Saéz-Aguayo, Susana; Blanco, Francisca; Mortimer, Jennifer C.; Schultink, Alex; Reiter, Wolf-Dieter; Dupree, Paul; Pauly, Markus; Heazlewood, Joshua L.; Scheller, Henrik V.; Orellana, Ariel

    2014-01-01

    Plant cells are surrounded by a cell wall that plays a key role in plant growth, structural integrity, and defense. The cell wall is a complex and diverse structure that is mainly composed of polysaccharides. The majority of noncellulosic cell wall polysaccharides are produced in the Golgi apparatus from nucleotide sugars that are predominantly synthesized in the cytosol. The transport of these nucleotide sugars from the cytosol into the Golgi lumen is a critical process for cell wall biosynthesis and is mediated by a family of nucleotide sugar transporters (NSTs). Numerous studies have sought to characterize substrate-specific transport by NSTs; however, the availability of certain substrates and a lack of robust methods have proven problematic. Consequently, we have developed a novel approach that combines reconstitution of NSTs into liposomes and the subsequent assessment of nucleotide sugar uptake by mass spectrometry. To address the limitation of substrate availability, we also developed a two-step reaction for the enzymatic synthesis of UDP–l-rhamnose (Rha) by expressing the two active domains of the Arabidopsis UDP–l-Rha synthase. The liposome approach and the newly synthesized substrates were used to analyze a clade of Arabidopsis NSTs, resulting in the identification and characterization of six bifunctional UDP–l-Rha/UDP–d-galactose (Gal) transporters (URGTs). Further analysis of loss-of-function and overexpression plants for two of these URGTs supported their roles in the transport of UDP–l-Rha and UDP–d-Gal for matrix polysaccharide biosynthesis. PMID:25053812

  10. Bifunctional compounds for controlling metal-mediated aggregation of the a?42 peptide.

    PubMed

    Sharma, Anuj K; Pavlova, Stephanie T; Kim, Jaekwang; Finkelstein, Darren; Hawco, Nicholas J; Rath, Nigam P; Kim, Jungsu; Mirica, Liviu M

    2012-04-18

    Abnormal interactions of Cu and Zn ions with the amyloid ? (A?) peptide are proposed to play an important role in the pathogenesis of Alzheimer's disease (AD). Disruption of these metal-peptide interactions using chemical agents holds considerable promise as a therapeutic strategy to combat this incurable disease. Reported herein are two bifunctional compounds (BFCs) L1 and L2 that contain both amyloid-binding and metal-chelating molecular motifs. Both L1 and L2 exhibit high stability constants for Cu(2+) and Zn(2+) and thus are good chelators for these metal ions. In addition, L1 and L2 show strong affinity toward A? species. Both compounds are efficient inhibitors of the metal-mediated aggregation of the A?(42) peptide and promote disaggregation of amyloid fibrils, as observed by ThT fluorescence, native gel electrophoresis/Western blotting, and transmission electron microscopy (TEM). Interestingly, the formation of soluble A?(42) oligomers in the presence of metal ions and BFCs leads to an increased cellular toxicity. These results suggest that for the A?(42) peptide-in contrast to the A?(40) peptide-the previously employed strategy of inhibiting A? aggregation and promoting amyloid fibril dissagregation may not be optimal for the development of potential AD therapeutics, due to formation of neurotoxic soluble A?(42) oligomers. PMID:22452395

  11. The determination of the rate of conjugation immunoglobuline with bifunctional chelator

    NASA Astrophysics Data System (ADS)

    Málek, Z.; Miler, V.; Budský, F.

    2006-01-01

    The work was performed under the GACR project: "Technology of preparation of radionuclides and their labelled compounds for nuclear medicine and pharmacy with the use of the reactor LVR-15" reg. no. 104/03/0499. Imaging of cell’s antigens with the use of labelled immunoglobulines allows imaging of specific receptors on cell membrane and specific tumours. It is necessary to carry out the labelling of the immunoglobulines with radionuclides of suitable physical properties, which form cations (e.g., 111In, 90Y, 177Lu) that form very strong chelates of sufficiently high stability constant preventing the dissociation of complexes or the radionuclide under “in-vivo” conditions. The immunoglobuline must be conjugated with the bifunctional chelator (BCH), which contains both chelating unit and reactive group for binding to the immunoglobuline. In our laboratory we have conjugated human IgG and monoclonal antibody CD20 with diethylenetriamine pentaacetic acid dianhydride (cDTPAA). Radionuclides 90Y and 177Lu prepared on the LVR-15 reactor in NRI Rez were used for labelling. After conjugation and labelling the yields in relation to the amount of isotopic carrier have been determined.

  12. Bifunctional Crosslinking Agents Enhance Anion Exchange Membrane Efficacy for Vanadium Redox Flow Batteries.

    PubMed

    Wang, Wenpin; Xu, Min; Wang, Shubo; Xie, Xiaofeng; Lv, Yafei; Ramani, Vijay K

    2014-06-01

    A series of cross-linked fluorinated poly (aryl ether oxadiazole) membranes (FPAEOM) derivatized with imidazolium groups were prepared. Poly (N-vinylimidazole) (PVI) was used as the bifunctional cross-linking agent to: a) lower vanadium permeability, b) enhance dimensional stability, and c) concomitantly provide added ion exchange capacity in the resultant anion exchange membranes. At a molar ratio of PVI to FPAEOM of 1.5, the resultant membrane (FPAEOM-1.5 PVI) had an ion exchange capacity of 2.2 meq g-1, a vanadium permeability of 6.8×10-7 cm2 min-1, a water uptake of 68 wt.%, and an ionic conductivity of 22.0 mS cm-1, all at 25°C. Single cells prepared with the FPAEOM-1.5 PVI membrane exhibited a higher coulombic efficiency (> 92%) and energy efficiency (> 86%) after 40 test cycles in vanadium redox flow battery. The imidazolium cation showed high chemical stability in highly acidic and oxidizing vanadium solution as opposed to poor stability in alkaline solutions. Based on our DFT studies, this was attributed to the lower HOMO energy (-7.265 eV) of the HSO4- ion (compared to the OH- ion; -5.496 eV) and the larger HOMO-LUMO energy gap (6.394 eV) of dimethylimidazolium bisulfate ([DMIM] [HSO4]) as compared to [DMIM] [OH] (5.387 eV). PMID:24884171

  13. High-resolution helix orientation in actin-bound myosin determined with a bifunctional spin label.

    PubMed

    Binder, Benjamin P; Cornea, Sinziana; Thompson, Andrew R; Moen, Rebecca J; Thomas, David D

    2015-06-30

    Using electron paramagnetic resonance (EPR) of a bifunctional spin label (BSL) bound stereospecifically to Dictyostelium myosin II, we determined with high resolution the orientation of individual structural elements in the catalytic domain while myosin is in complex with actin. BSL was attached to a pair of engineered cysteine side chains four residues apart on known ?-helical segments, within a construct of the myosin catalytic domain that lacks other reactive cysteines. EPR spectra of BSL-myosin bound to actin in oriented muscle fibers showed sharp three-line spectra, indicating a well-defined orientation relative to the actin filament axis. Spectral analysis indicated that orientation of the spin label can be determined within <2.1° accuracy, and comparison with existing structural data in the absence of nucleotide indicates that helix orientation can also be determined with <4.2° accuracy. We used this approach to examine the crucial ADP release step in myosin's catalytic cycle and detected reversible rotations of two helices in actin-bound myosin in response to ADP binding and dissociation. One of these rotations has not been observed in myosin-only crystal structures. PMID:26056276

  14. Structure of the E. Coli Bifunctional GlmU Acetyltransferase Active Site with Substrates and Products

    SciTech Connect

    Olsen,L.; Vetting, M.; Roderick, S.

    2007-01-01

    The biosynthesis of UDP-GlcNAc in bacteria is carried out by GlmU, an essential bifunctional uridyltransferase that catalyzes the CoA-dependent acetylation of GlcN-1-PO{sub 4} to form GlcNAc-1-PO{sub 4} and its subsequent condensation with UTP to form pyrophosphate and UDP-GlcNAc. As a metabolite, UDP-GlcNAc is situated at a branch point leading to the biosynthesis of lipopolysaccharide and peptidoglycan. Consequently, GlmU is regarded as an important target for potential antibacterial agents. The crystal structure of the Escherichia coli GlmU acetyltransferase active site has been determined in complexes with acetyl-CoA, CoA/GlcN-1-PO{sub 4}, and desulpho-CoA/GlcNAc-1-PO{sub 4}. These structures reveal the enzyme groups responsible for binding the substrates. A superposition of these complex structures suggests that the 2-amino group of GlcN-1-PO{sub 4} is positioned in proximity to the acetyl-CoA to facilitate direct attack on its thioester by a ternary complex mechanism.

  15. Production of a bifunctional hybrid molecule B72.3/metallothionein-1 by protein engineering.

    PubMed Central

    Xiang, J; Koropatnick, J; Qi, Y; Luo, X; Moyana, T; Li, K; Chen, Y

    1993-01-01

    A hybrid anti-tumour B72.3 antibody/metallothionein protein B72.3MT-1 was produced by the construction of the expression vector mpSV2neo-EP1-B72.3MT-1. This vector contained the neo gene as a selection marker, the murine immunoglobulin promoter and enhancer, and the hybrid B72.3 heavy chain gene fragment with mouse metallothionein-1 cDNA gene ligated into its CH2 domain. The expression vector was transfected to the heavy chain loss mutant B72.3Mut(K) cell line. The hybrid protein B72.3MT-1 was purified from transfectant supernates using a Protein G column. We showed that the hybrid protein retained the binding reactivity for the TAG72 antigen as the original B72.3 antibody, and the metal-binding capacity of the native metallothionein molecule. Therefore, the bifunctional hybrid protein B72.3MT-1 may be very useful in cancer imaging when labelled with radionuclides such as 99mTc. Images Figure 3 Figure 6 Figure 7 PMID:8495976

  16. Gradient Tempering Of Bearing Races

    NASA Technical Reports Server (NTRS)

    Parr, Richardson A.

    1991-01-01

    Gradient-tempering process increases fracture toughness and resistance to stress-corrosion cracking of ball-bearing races made of hard, strong steels and subject to high installation stresses and operation in corrosive media. Also used in other applications in which local toughening of high-strength/low-toughness materials required.

  17. Radiation tolerance in water bears

    Microsoft Academic Search

    D. D. Horikawa; T. Sakashita; C. Katagiri; M. Watanabe; Y. Nakahara; T. Okuda; N. Hamada; S. Wada; T. Funayama; Y. Kobayashi

    2006-01-01

    Tardigrades water bears are tiny invertebrates forming a phylum and inhabit various environments on the earth Terrestrial tardigrades enter a form called as anhydrobiosis when the surrounding water disappears Anhyydrobiosis is defined as an ametabolic dry state and followed by recovering their activity when rehydrated Anhydrobiotic tardigrades show incredible tolerance to a variety of extreme environmental conditions such as temperatures

  18. Hybrid bearings for turbopumps and the like

    NASA Technical Reports Server (NTRS)

    Justak, John F. (inventor); Owens, Gregg R. (inventor)

    1994-01-01

    In rocket engines power is usually obtained by burning fuel and oxidizer which are mixed, pressurized, and directed to a combustion chamber by means of turbopumps. Roller bearings are generally used in these turbopumps, but because of bearing demands hydrostatic bearings were proposed. The use of such bearings is quite feasible because during flight hydrostatic lubrication can reduce roller bearing wear. A disadvantage of such proposals is that during startup, acceleration, and shutdown high pressure fluids are not available for hydrostatic bearings. The fluid lubrication film is not always present in bearings of turbopumps. During these periods a second bearing is required to carry the load. This requirement suggests the use of hybrid bearings in rocket engine turbopumps. Such duplex bearings were provided, but when their inner races are keyed to the shaft or journal two of them are required. And such duplex bearings do not wear evenly. A hybrid hydrostatic-rolling element bearing was provided wherein the rolling element bearing is locked on the stationary housing rather than on the rotating journal.

  19. Design of a low cost hydrostatic bearing

    E-print Network

    Wong, Anthony Raymond

    2012-01-01

    This thesis presents the design and manufacturing method for a new surface self compensating hydrostatic bearing. A lumped resistance model was used to analyze the performance of the bearing and provide guidance on laying ...

  20. High Temperature, Permanent Magnet Biased Magnetic Bearings 

    E-print Network

    Gandhi, Varun R.

    2010-07-14

    The Electron Energy Corporation (EEC) along with the National Aeronautics and Space Administration (NASA) is researching magnetic bearings. The purpose of this research was to design and develop a high-temperature (1000?F) magnetic bearing system...

  1. Hunting for 'bears' in the backyard

    NSDL National Science Digital Library

    Dave Walker

    This Micscape Magazine article offers practical hints about how to collect and study tardigrades, or water bears, from mosses in your backyard. It features a general introduction of water bears, a video, and a section of references for further reading.

  2. Bear-inflicted human injury and fatality.

    PubMed

    Floyd, T

    1999-01-01

    This review attempts to summarize credible scientific information, and to dispel myths, regarding bear attacks. Publications in the scientific literature were sought through a Medline search and by reviewing the bibliographies of related books and scientific articles. Personal experience and interviews with authorities were also used in preparation of this review, although only published articles or books are cited. This is a summary of case series reported or observed elsewhere. Bear-inflicted human injury and death is rare. Brown bear attacks tend to be severe and to occur suddenly, without provocation. Black bear attacks usually result in minor injuries and tend to be predacious. Polar bear attacks are exceedingly rare, and the ferocity of polar bears has probably been overemphasized. Bear-inflicted wounds should be treated as major trauma in accordance with advanced trauma life support guidelines. This information may be useful in counseling patients with regard to prevention of injury or death from bear attack. PMID:10442155

  3. Rolling Element Bearing Stiffness Matrix Determination (Presentation)

    SciTech Connect

    Guo, Y.; Parker, R.

    2014-01-01

    Current theoretical bearing models differ in their stiffness estimates because of different model assumptions. In this study, a finite element/contact mechanics model is developed for rolling element bearings with the focus of obtaining accurate bearing stiffness for a wide range of bearing types and parameters. A combined surface integral and finite element method is used to solve for the contact mechanics between the rolling elements and races. This model captures the time-dependent characteristics of the bearing contact due to the orbital motion of the rolling elements. A numerical method is developed to determine the full bearing stiffness matrix corresponding to two radial, one axial, and two angular coordinates; the rotation about the shaft axis is free by design. This proposed stiffness determination method is validated against experiments in the literature and compared to existing analytical models and widely used advanced computational methods. The fully-populated stiffness matrix demonstrates the coupling between bearing radial, axial, and tilting bearing deflections.

  4. Bearing fault diagnosis based on rough set

    Microsoft Academic Search

    Chen Xin; Yuhua Chen; Guofeng Wang; Hu Dong

    2010-01-01

    Bearing defects were categorized as localized and distributed. For on-line bearing fault diagnosis, in this paper, the time-domain kurtosis calculation and the frequency domain wavelet analysis were used to extract the transitory features of non-stationary vibration signal produced by the bearing distributed defects. To distributed defects, bearing fault diagnosis was built on the reducing decision based on rough set. According

  5. Notes 16. Analysis of tilting pad bearings

    E-print Network

    San Andres, Luis

    2010-01-01

    installed to carry a static load on a pad (LOP) or a static load in between pads (LBP). Commercial tilting pad bearings have various pivot designs such as rocker pivots (line contact), spherical pivots (point contact) and flexure supported pivots.... Figure 1. Schematic view of a four pad tilting pad bearing, Ref. [1] Accurate prediction of tilting pad bearing forces and force coefficients is essential to design and predict the dynamic performance of rotor-bearing systems. Parameters affecting...

  6. Effects of bearing deadbands on bearing loads and rotor stability

    NASA Technical Reports Server (NTRS)

    1984-01-01

    A generic model of a turbopump, simplified to bring out these effects is examined. This model demonstrates that bearing deadbands which are of the same order of magnitude or larger than the center-of-mass offset of a rotor due to mass imbalances cause significantly different dynamic behavior than would be expected of a linear, dynamical system. This fundamentally nonlinear behavior yields altered stability characteristics and altered bearing loading tendencies. It is shown that side forces can enhance system stability in the small, i.e., as long as the mass imbalance does not exceed some thresholds value or as long as no large, impulsive disturbances cause the motion to depart significantly from the region of stability. Limit cycles are investigated in this report and techniques for determining these limit cycles are developed. These limit cycles are the major source of bearing loading and appear in both synchronous and nonsynchronous forms. The synchronous limit cycles are driven by rotor imbalances. The nonsynchronous limit cycles (also called subsynchronous whirls) are self-excited and are the sources of instability.

  7. Seismic evaluation of a large nuclear pump bearing using non-linear dynamic analysis

    SciTech Connect

    Huber, K.A.; Hugins, M.S.

    1983-01-01

    Hydrostatic bearings of a large vertical pump using sodium as the lubricant were critically examined to determine their ability to withstand seismic loads. Initial linear dynamics analyses predicted journal displacements to exceed bearing clearance by a ratio of 3:1. Equivalent time-history excitations were then developed from the response spectra to determine the number, magnitude, and duration of the bearing impact loads. Predicted loads were further reduced by 50% by modeling non-linear bearing characteristics normally present but not generally included in conventional linear analyses. Results are presented of the comprehensive design evaluation performed, based on these non-linear predictions, that assess stress, wear, and fatigue to demonstrate hydrostatic bearing integrity.

  8. Bearing diagnosis based on Mahalanobis-Taguchi-Gram-Schmidt method

    NASA Astrophysics Data System (ADS)

    Shakya, Piyush; Kulkarni, Makarand S.; Darpe, Ashish K.

    2015-02-01

    A methodology is developed for defect type identification in rolling element bearings using the integrated Mahalanobis-Taguchi-Gram-Schmidt (MTGS) method. Vibration data recorded from bearings with seeded defects on outer race, inner race and balls are processed in time, frequency, and time-frequency domains. Eleven damage identification parameters (RMS, Peak, Crest Factor, and Kurtosis in time domain, amplitude of outer race, inner race, and ball defect frequencies in FFT spectrum and HFRT spectrum in frequency domain and peak of HHT spectrum in time-frequency domain) are computed. Using MTGS, these damage identification parameters (DIPs) are fused into a single DIP, Mahalanobis distance (MD), and gain values for the presence of all DIPs are calculated. The gain value is used to identify the usefulness of DIP and the DIPs with positive gain are again fused into MD by using Gram-Schmidt Orthogonalization process (GSP) in order to calculate Gram-Schmidt Vectors (GSVs). Among the remaining DIPs, sign of GSVs of frequency domain DIPs is checked to classify the probable defect. The approach uses MTGS method for combining the damage parameters and in conjunction with the GSV classifies the defect. A Defect Occurrence Index (DOI) is proposed to rank the probability of existence of a type of bearing damage (ball defect/inner race defect/outer race defect/other anomalies). The methodology is successfully validated on vibration data from a different machine, bearing type and shape/configuration of the defect. The proposed methodology is also applied on the vibration data acquired from the accelerated life test on the bearings, which established the applicability of the method on naturally induced and naturally progressed defect. It is observed that the methodology successfully identifies the correct type of bearing defect. The proposed methodology is also useful in identifying the time of initiation of a defect and has potential for implementation in a real time environment.

  9. 14 CFR 23.623 - Bearing factors.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ...2014-01-01 2014-01-01 false Bearing factors. 23.623 Section 23.623...Design and Construction § 23.623 Bearing factors. (a) Each part that has...to pounding or vibration, must have a bearing factor large enough to provide for...

  10. 14 CFR 23.623 - Bearing factors.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ...2010-01-01 2010-01-01 false Bearing factors. 23.623 Section 23.623...Design and Construction § 23.623 Bearing factors. (a) Each part that has...to pounding or vibration, must have a bearing factor large enough to provide for...

  11. 14 CFR 27.623 - Bearing factors.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ...2012-01-01 2012-01-01 false Bearing factors. 27.623 Section 27.623...Construction General § 27.623 Bearing factors. (a) Except as provided...to pounding or vibration, must have a bearing factor large enough to provide for...

  12. 14 CFR 27.623 - Bearing factors.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ...2011-01-01 2011-01-01 false Bearing factors. 27.623 Section 27.623...Construction General § 27.623 Bearing factors. (a) Except as provided...to pounding or vibration, must have a bearing factor large enough to provide for...

  13. 14 CFR 29.623 - Bearing factors.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ...2010-01-01 2010-01-01 false Bearing factors. 29.623 Section 29.623...Construction General § 29.623 Bearing factors. (a) Except as provided...to pounding or vibration, must have a bearing factor large enough to provide for...

  14. 14 CFR 23.623 - Bearing factors.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ...2012-01-01 2012-01-01 false Bearing factors. 23.623 Section 23.623...Design and Construction § 23.623 Bearing factors. (a) Each part that has...to pounding or vibration, must have a bearing factor large enough to provide for...

  15. 14 CFR 29.623 - Bearing factors.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ...2012-01-01 2012-01-01 false Bearing factors. 29.623 Section 29.623...Construction General § 29.623 Bearing factors. (a) Except as provided...to pounding or vibration, must have a bearing factor large enough to provide for...

  16. 14 CFR 29.623 - Bearing factors.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ...2011-01-01 2011-01-01 false Bearing factors. 29.623 Section 29.623...Construction General § 29.623 Bearing factors. (a) Except as provided...to pounding or vibration, must have a bearing factor large enough to provide for...

  17. 14 CFR 23.623 - Bearing factors.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ...2011-01-01 2011-01-01 false Bearing factors. 23.623 Section 23.623...Design and Construction § 23.623 Bearing factors. (a) Each part that has...to pounding or vibration, must have a bearing factor large enough to provide for...

  18. 14 CFR 25.623 - Bearing factors.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ...2013-01-01 2013-01-01 false Bearing factors. 25.623 Section 25.623...Construction General § 25.623 Bearing factors. (a) Except as provided...to pounding or vibration, must have a bearing factor large enough to provide for...

  19. Induction Motors Bearing Failures Detection and Diagnosis

    E-print Network

    Boyer, Edmond

    331 1 Induction Motors Bearing Failures Detection and Diagnosis Using a RBF ANN Park Pattern Based Method I. Y. Önel, I. enol and M. E. H. Benbouzid Abstract--This paper deals with the problem of bearing detection and diagnosis process. Experimental tests with artificial bearing damages results show

  20. 14 CFR 29.623 - Bearing factors.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ...2013-01-01 2013-01-01 false Bearing factors. 29.623 Section 29.623...Construction General § 29.623 Bearing factors. (a) Except as provided...to pounding or vibration, must have a bearing factor large enough to provide for...

  1. 14 CFR 25.623 - Bearing factors.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ...2012-01-01 2012-01-01 false Bearing factors. 25.623 Section 25.623...Construction General § 25.623 Bearing factors. (a) Except as provided...to pounding or vibration, must have a bearing factor large enough to provide for...

  2. 14 CFR 25.623 - Bearing factors.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ...2010-01-01 2010-01-01 false Bearing factors. 25.623 Section 25.623...Construction General § 25.623 Bearing factors. (a) Except as provided...to pounding or vibration, must have a bearing factor large enough to provide for...

  3. 14 CFR 29.623 - Bearing factors.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ...2014-01-01 2014-01-01 false Bearing factors. 29.623 Section 29.623...Construction General § 29.623 Bearing factors. (a) Except as provided...to pounding or vibration, must have a bearing factor large enough to provide for...

  4. 14 CFR 27.623 - Bearing factors.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ...2013-01-01 2013-01-01 false Bearing factors. 27.623 Section 27.623...Construction General § 27.623 Bearing factors. (a) Except as provided...to pounding or vibration, must have a bearing factor large enough to provide for...

  5. 14 CFR 27.623 - Bearing factors.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ...2014-01-01 2014-01-01 false Bearing factors. 27.623 Section 27.623...Construction General § 27.623 Bearing factors. (a) Except as provided...to pounding or vibration, must have a bearing factor large enough to provide for...

  6. 14 CFR 23.623 - Bearing factors.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ...2013-01-01 2013-01-01 false Bearing factors. 23.623 Section 23.623...Design and Construction § 23.623 Bearing factors. (a) Each part that has...to pounding or vibration, must have a bearing factor large enough to provide for...

  7. 14 CFR 27.623 - Bearing factors.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ...2010-01-01 2010-01-01 false Bearing factors. 27.623 Section 27.623...Construction General § 27.623 Bearing factors. (a) Except as provided...to pounding or vibration, must have a bearing factor large enough to provide for...

  8. 14 CFR 25.623 - Bearing factors.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ...2014-01-01 2014-01-01 false Bearing factors. 25.623 Section 25.623...Construction General § 25.623 Bearing factors. (a) Except as provided...to pounding or vibration, must have a bearing factor large enough to provide for...

  9. 14 CFR 25.623 - Bearing factors.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ...2011-01-01 2011-01-01 false Bearing factors. 25.623 Section 25.623...Construction General § 25.623 Bearing factors. (a) Except as provided...to pounding or vibration, must have a bearing factor large enough to provide for...

  10. CURIOSITY IN THE AMERICAN BLACK BEAR

    Microsoft Academic Search

    ELLIS S. BACON

    American black bears (Ursus americanus) were tested to quantify their response to novel objects placed in their environment. The results indicate that the level of orientation may be greater in the black bear than in other North American carnivores. The exploration of objects by the black bear is characterized by a high degree of contact with the objects. This contact

  11. Hydrology of the Bear Lake Basin, Utah

    Microsoft Academic Search

    Patsy Palacios; Chris Luecke; Justin Robinson

    2007-01-01

    Bear Lake’s natural watershed is made up of relatively low mountains covered with sagebrush at lower elevations and southern exposures and fir-aspen forests at higher elevations and northern exposures. The basin is traversed by the Bear River that begins high in the Unita Mountains and flows through Utah, Idaho, and Wyoming before feeding the Great Salt Lake. The Bear River

  12. Passive Thermal Management of Foil Bearings

    NASA Technical Reports Server (NTRS)

    Bruckner, Robert J. (Inventor)

    2015-01-01

    Systems and methods for passive thermal management of foil bearing systems are disclosed herein. The flow of the hydrodynamic film across the surface of bearing compliant foils may be disrupted to provide passive cooling and to improve the performance and reliability of the foil bearing system.

  13. Hybrid air foil bearing with external pressurization 

    E-print Network

    Park, Soongook

    2009-05-15

    Foil bearings are widely used for oil-free micro turbomachinery. One of the critical technical issues related to reliability of the foil bearings is a coating wear on the top foil and rotor during start/stops. Bearing cooling is also mandatory...

  14. FOSTERING BLACK BEAR CUBS IN THE WILD

    Microsoft Academic Search

    STEPHEN H. CLARKE; CHARLES HACKFORD

    Three black bear (Ursus americanus) cubs were abandoned, at approximately 2 weeks of age, on 4 February 1976, in New York State's Catskill region. The dens of 4 radio-telemetered adult female bears were located by the Department of Environmental Conservation during research on the black bear population in the Catskills. Two of the abandoned cubs were placed in the only

  15. Dare to Care for a Grizzly Bear

    NSDL National Science Digital Library

    2008-10-31

    Using the Nature episode “The Good, The Bad and the Grizzly,” students will be able to articulate the complex and competing perspectives on how to best handle the growing bear population, and they will investigate the factors contributing to the destabilization of the bear’s Yellowstone ecosystem.

  16. 36 CFR 13.1236 - Bear orientation.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ...2011-07-01 2011-07-01 false Bear orientation. 13.1236 Section 13...Brooks Camp Developed Area § 13.1236 Bear orientation. All persons visiting the BCDA must receive an NPS-approved Bear Orientation. Failure to receive an...

  17. 36 CFR 13.1236 - Bear orientation.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ...2010-07-01 2010-07-01 false Bear orientation. 13.1236 Section 13...Brooks Camp Developed Area § 13.1236 Bear orientation. All persons visiting the BCDA must receive an NPS-approved Bear Orientation. Failure to receive an...

  18. Rolling element bearing design through genetic algorithms

    Microsoft Academic Search

    Indraneel Chakraborty; Vinay Kumar; Shivashankar B. Nair; Rajiv Tiwari

    2003-01-01

    The design of rolling element bearings has been a challenging task in the field of mechanical engineering. While most of the real aspects of the design are never disclosed by bearing manufacturers, the common engineer is left with no other alternative than to refer to standard tables and charts containing the bearing performance characteristics. This paper presents a more viable

  19. Fault tolerant control of active magnetic bearings

    Microsoft Academic Search

    P. Schroder; A. J. Chipperfield; P. J. Fleming; N. Grum

    1998-01-01

    A nonlinear model of a Rolls-Royce turbomachine's rotor supported by active magnetic bearings (AMBs) is presented. The model has the capability to model magnetic bearing systems of a variety of different configurations. A multiobjective genetic algorithm (MOGA) is used to design PID controllers for the AMB system with five different bearing configurations. A centralised fault compensation scheme is demonstrated and

  20. Superconducting magnetic bearings for energy storage flywheels

    Microsoft Academic Search

    T. Coombs; A. M. Campbell; R. Storey; R. Weller

    1999-01-01

    We are investigating the use of flywheels for energy storage. Flywheel devices need to be of high efficiency and an important source of losses is the bearings. In addition, the requirement is for the devices to have long lifetimes with minimal or no maintenance. Conventional rolling element bearings can and have been used, but a noncontact bearing, such as a

  1. Cool Polar Bears: Dabbing on the Texture

    ERIC Educational Resources Information Center

    O'Connell, Jean

    2011-01-01

    In this article, the author describes how her second-graders created their cool polar bears. The students used the elements of shape and texture to create the bears. They used Monet's technique of dabbing paint so as to give the bear some texture on his fur.

  2. Minimizing electric bearing currents in ASD systems

    Microsoft Academic Search

    P. J. Link

    1999-01-01

    During recent years, an increase in bearing failures has been seen in ASD-fed electric motors, as well as in gearboxes, and other connected machinery, caused by electric current flow through such bearings. The theories presented in this paper focus on bearing currents in ASDs of the voltage source pulse width modulated (PWM) type, for use with AC induction motors, although

  3. White-etching matter in bearing steel Part 2: Distinguishing cause and eect in bearing steel

    E-print Network

    Cambridge, University of

    White-etching matter in bearing steel Part 2: Distinguishing cause and eect in bearing steel of Cambridge, U.K Abstract The premature failure of large bearings of the type used in wind turbines, possibly as reported observations on real bearings. Evidence suggests that the formation mechanism of the white

  4. Delivery of bifunctional RNAs that target an intronic repressor and increase SMN levels in an animal model of spinal muscular atrophy

    PubMed Central

    Baughan, Travis D.; Dickson, Alexa; Osman, Erkan Y.; Lorson, Christian L.

    2009-01-01

    Spinal muscular atrophy (SMA) is a motor neuron disease caused by the loss of survival motor neuron-1 (SMN1). A nearly identical copy gene, SMN2, is present in all SMA patients, which produces low levels of functional protein. Although the SMN2 coding sequence has the potential to produce normal, full-length SMN, ?90% of SMN2-derived transcripts are alternatively spliced and encode a truncated protein lacking the final coding exon (exon 7). SMN2, however, is an excellent therapeutic target. Previously, we developed bifunctional RNAs that bound SMN exon 7 and modulated SMN2 splicing. To optimize the efficiency of the bifunctional RNAs, a different antisense target was required. To this end, we genetically verified the identity of a putative intronic repressor and developed bifunctional RNAs that target this sequence. Consequently, there is a 2-fold mechanism of SMN induction: inhibition of the intronic repressor and recruitment of SR proteins via the SR recruitment sequence of the bifunctional RNA. The bifunctional RNAs effectively increased SMN in human primary SMA fibroblasts. Lead candidates were synthesized as 2?-O-methyl RNAs and were directly injected in the central nervous system of SMA mice. Single-RNA injections were able to illicit a robust induction of SMN protein in the brain and throughout the spinal column of neonatal SMA mice. In a severe model of SMA, mean life span was extended following the delivery of bifunctional RNAs. This technology has direct implications for the development of an SMA therapy, but also lends itself to a multitude of diseases caused by aberrant pre-mRNA splicing. PMID:19228773

  5. Cu-catalyzed selective mono-N-pyridylation: direct access to 2-aminoDMAP/sulfonamides as bifunctional organocatalysts.

    PubMed

    Isik, Murat; Tanyeli, Cihangir

    2013-02-15

    Direct and selective mono-N-pyridylation of trans-(R,R)-cyclohexane-1,2-diamine is described here. Facile preparation of a novel chiral 2-aminoDMAP core catalaphore via Cu catalysis has led to the development of various sulfonamide/2-aminoDMAPs as bifunctional acid/base organocatalysts (most in two steps overall), which have been shown to very effectively promote asymmetric conjugate addition of acetylacetone to trans-?-nitroolefins with good to excellent yields (87-93%) and enantioselectivites (up to 99%). PMID:23331280

  6. Recyclable Bifunctional Polystyrene and Silica Gel-Supported Organocatalyst for the Coupling of CO2 with Epoxides.

    PubMed

    Kohrt, Christina; Werner, Thomas

    2015-06-22

    A bifunctional ammonium salt covalently bound to a polystyrene or silica support proved to be an efficient and recyclable catalyst for the solvent-free synthesis of cyclic carbonates from epoxides and CO2 . The catalyst can be easily recovered by simple filtration after the reaction and reused in up to 13 consecutive runs with retention of high activity and selectivity even at 90?°C. The scope and limitations of the reaction has been evaluated in terms of reaction conditions and substrate scope. PMID:25872906

  7. A nucleotide insertion between two adjacent methyltransferases in Helicobacter pylori results in a bifunctional DNA methyltransferase.

    PubMed

    Kumar, Ritesh; Rao, Desirazu N

    2011-02-01

    Helicobacter pylori has a dynamic R-M (restriction-modification) system. It is capable of acquiring new R-M systems from the environment in the form of DNA released from other bacteria or other H. pylori strains. Random mutations in R-M genes can result in non-functional R-M systems or R-M systems with new properties. hpyAVIAM and hpyAVIBM are two solitary DNA MTase (methyltransferase) genes adjacent to each other and lacking a cognate restriction enzyme gene in H. pylori strain 26695. Interestingly, in an Indian strain D27, hpyAVIAM-hpyAVIBM encodes a single bifunctional polypeptide due to insertion of a nucleotide just before the stop codon of hpyAVIBM and, when a similar mutation was made in hpyAVIAM-hpyAVIBM from strain 26695, a functional MTase with an N-terminal C?-cytosine MTase domain and a C-terminal N?-adenine MTase domain was constructed. Mutations in the AdoMet (S-adenosylmethionine)-binding motif or in the catalytic motif of M.HpyAVIA or M.HpyAVIB selectively abrogated the C?-cytosine or N?-adenine methylation activity of M.HpyAVIA-M.HpyAVIB fusion protein. The present study highlights the ability of H. pylori to evolve genes with unique functions and thus generate variability. For organisms such as H. pylori, which have a small genome, these adaptations could be important for their survival in the hostile host environment. PMID:21110832

  8. Domain Organization in Candida glabrata THI6, a Bifunctional Enzyme Required for Thiamin Biosynthesis in Eukaryotes

    SciTech Connect

    Paul, Debamita; Chatterjee, Abhishek; Begley, Tadhg P.; Ealick, Steven E. (Cornell); (TAM)

    2010-11-15

    THI6 is a bifunctional enzyme found in the thiamin biosynthetic pathway in eukaryotes. The N-terminal domain of THI6 catalyzes the ligation of the thiamin thiazole and pyrimidine moieties to form thiamin phosphate, and the C-terminal domain catalyzes the phosphorylation of 4-methyl-5-hydroxyethylthiazole in a salvage pathway. In prokaryotes, thiamin phosphate synthase and 4-methyl-5-hydroxyethylthiazole kinase are separate gene products. Here we report the first crystal structure of a eukaryotic THI6 along with several complexes that characterize the active sites responsible for the two chemical reactions. THI6 from Candida glabrata is a homohexamer in which the six protomers form a cage-like structure. Each protomer is composed of two domains, which are structurally homologous to their monofunctional bacterial counterparts. Two loop regions not found in the bacterial enzymes provide interactions between the two domains. The structures of different protein-ligand complexes define the thiazole and ATP binding sites of the 4-methyl-5-hydroxyethylthiazole kinase domain and the thiazole phosphate and 4-amino-5-hydroxymethyl-2-methylpyrimidine pyrophosphate binding sites of the thiamin phosphate synthase domain. Our structural studies reveal that the active sites of the two domains are 40 {angstrom} apart and are not connected by an obvious channel. Biochemical studies show 4-methyl-5-hydroxyethylthiazole phosphate is a substrate for THI6; however, adenosine diphospho-5{beta}-ethyl-4-methylthiazole-2-carboxylic acid, the product of THI4, is not a substrate for THI6. This suggests that an unidentified enzyme is necessary to produce the substrate for THI6 from the THI4 product.

  9. Thrombolytic, anticoagulant and antiplatelet activities of codiase, a bi-functional fibrinolytic enzyme from Codium fragile.

    PubMed

    Choi, Jun-Hui; Sapkota, Kumar; Park, Se-Eun; Kim, Seung; Kim, Sung-Jun

    2013-06-01

    Thrombosis is a leading cause of morbidity and mortality throughout the world. Thrombolytic agents are important for both the prevention and treatment of thrombosis. In this study, codiase, a new bi-functional fibrinolytic serine protease having thrombolytic, anticoagulant, and antiplatelet activities was purified from marine green alga, Codium fragile. The molecular weight of the enzyme was estimated to be 48.9 kDa by SDS-PAGE, and mass spectrometry. Fibrin zymography analysis showed an active band with similar molecular weight. The N-terminal sequence was found to be APKASTDQTLPL, which is different from that of other known fibrinolytic enzymes. Codiase displayed maximum activity at 30 °C and pH 6.0, and the activity was inhibited by Zn(2+) and Fe(2+). Moreover, the enzyme activity was strongly inhibited by serine protease inhibitor such as PMSF. Codiase exhibited high specificity for the substrate S-2288, and the Km and Vmax values for this substrate were found to be 0.24 mM and 79 U/ml respectively. Fibrin plate assays revealed that it was able to hydrolyze fibrin clot either directly or by activation of plasminogen. Codiase effectively hydrolyzed fibrin and fibrinogen, preferentially degrading ?- and A? chains, followed by ?-?, and ?-chains. However, it provoked slower degradation of B? and ?-chains. The structural change of fibrin clot and fibrinogen by codiase was also detected by FTIR-ATR spectroscopy analysis. In vitro and in vivo studies revealed that codiase reduces thrombosis in concentration-dependent manner. Codiase was found to prolong activated partial thromboplastin time (APTT), and prothrombin time (PT). PFA-100 studies showed that codiase prolonged the closure time (CT) of citrated whole human blood. These favorable antithrombotic profiles together with its anticoagulant and platelet disaggregation properties, and lack of toxicity to mice and NIH-3T3 cells, make it a potential agent for thrombolytic therapy. PMID:23402909

  10. Mutational spectrum of D-bifunctional protein deficiency and structure-based genotype-phenotype analysis.

    PubMed

    Ferdinandusse, Sacha; Ylianttila, Mari S; Gloerich, Jolein; Koski, M Kristian; Oostheim, Wendy; Waterham, Hans R; Hiltunen, J Kalervo; Wanders, Ronald J A; Glumoff, Tuomo

    2006-01-01

    D-bifunctional protein (DBP) deficiency is an autosomal recessive inborn error of peroxisomal fatty acid oxidation. The clinical presentation of DBP deficiency is usually very severe, but a few patients with a relatively mild presentation have been identified. In this article, we report the mutational spectrum of DBP deficiency on the basis of molecular analysis in 110 patients. We identified 61 different mutations by DBP cDNA analysis, 48 of which have not been reported previously. The predicted effects of the different disease-causing amino acid changes on protein structure were determined using the crystal structures of the (3R)-hydroxyacyl-coenzyme A (CoA) dehydrogenase unit of rat DBP and the 2-enoyl-CoA hydratase 2 unit and liganded sterol carrier protein 2-like unit of human DBP. The effects ranged from the replacement of catalytic amino acid residues or residues in direct contact with the substrate or cofactor to disturbances of protein folding or dimerization of the subunits. To study whether there is a genotype-phenotype correlation for DBP deficiency, these structure-based analyses were combined with extensive biochemical analyses of patient material (cultured skin fibroblasts and plasma) and available clinical information on the patients. We found that the effect of the mutations identified in patients with a relatively mild clinical and biochemical presentation was less detrimental to the protein structure than the effect of mutations identified in those with a very severe presentation. These results suggest that the amount of residual DBP activity correlates with the severity of the phenotype. From our data, we conclude that, on the basis of the predicted effect of the mutations on protein structure, a genotype-phenotype correlation exists for DBP deficiency. PMID:16385454

  11. A metal-free bifunctional electrocatalyst for oxygen reduction and oxygen evolution reactions.

    PubMed

    Zhang, Jintao; Zhao, Zhenghang; Xia, Zhenhai; Dai, Liming

    2015-05-01

    The oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) are traditionally carried out with noble metals (such as Pt) and metal oxides (such as RuO2 and MnO2) as catalysts, respectively. However, these metal-based catalysts often suffer from multiple disadvantages, including high cost, low selectivity, poor stability and detrimental environmental effects. Here, we describe a mesoporous carbon foam co-doped with nitrogen and phosphorus that has a large surface area of ?1,663?m(2)?g(-1) and good electrocatalytic properties for both ORR and OER. This material was fabricated using a scalable, one-step process involving the pyrolysis of a polyaniline aerogel synthesized in the presence of phytic acid. We then tested the suitability of this N,P-doped carbon foam as an air electrode for primary and rechargeable Zn-air batteries. Primary batteries demonstrated an open-circuit potential of 1.48?V, a specific capacity of 735?mAh?gZn(-1) (corresponding to an energy density of 835?Wh?kgZn(-1)), a peak power density of 55?mW?cm(-2), and stable operation for 240?h after mechanical recharging. Two-electrode rechargeable batteries could be cycled stably for 180 cycles at 2?mA?cm(-2). We also examine the activity of our carbon foam for both OER and ORR independently, in a three-electrode configuration, and discuss ways in which the Zn-air battery can be further improved. Finally, our density functional theory calculations reveal that the N,P co-doping and graphene edge effects are essential for the bifunctional electrocatalytic activity of our material. PMID:25849787

  12. Bifunctional reactivity of amidoximes observed upon nucleophilic addition to metal-activated nitriles.

    PubMed

    Bolotin, Dmitrii S; Demakova, Marina Ya; Novikov, Alexander S; Avdontceva, Margarita S; Kuznetsov, Maxim L; Bokach, Nadezhda A; Kukushkin, Vadim Yu

    2015-04-20

    Treatment of the aromatic nitrile complexes trans-[PtCl2(RC6H4CN)2] (R = p-CF3 NC1, H NC2, o-Cl NC3) with the aryl amidoximes p-R'C6H4C(NH2)=NOH (R' = Me AO1, H AO2, Br AO3, CF3 AO4, NO2 AO5) in all combinations, followed by addition of 1 equiv of AgOTf and then 5 equiv of Et3N, leads to the chelates [PtCl{HN=C(RC6H4)ON=C(C6H4R'-p)NC(RC6H4)?NH}] (1-15; 15 examples; yields 71-88% after column chromatography) derived from the platinum(II)-mediated coupling between metal-activated nitriles and amidoximes. The mechanism of this reaction was studied experimentally by trapping and identification of the reaction intermediates, and it was also investigated theoretically at the DFT level of theory. The combined experimental and theoretical results indicate that the coupling with the nitrile ligands involves both the HON and monodeprotonated NH2 groups of the amidoximes, whereas in the absence of the base, the NH2 functionality is inactive toward the coupling. The observed reaction represents the first example of bifunctional nucleophilic behavior of amidoximes. The complexes 1-16 were characterized by elemental analyses (C, H, N), high-resolution ESI(+)-MS, FTIR, and (1)H NMR techniques, whereas unstable 17 was characterized by HRESI(+)-MS and FTIR. In addition, 8·C4H8O2, 12, and 16·CHCl3 were studied by single-crystal X-ray diffraction. PMID:25822628

  13. Fast and reliable production, purification and characterization of heat-stable, bifunctional enzyme chimeras.

    PubMed

    Neddersen, Mara; Elleuche, Skander

    2015-12-01

    Degradation of complex plant biomass demands a fine-regulated portfolio of glycoside hydrolases. The LE (LguI/Eco81I)-cloning approach was used to produce two enzyme chimeras CB and BC composed of an endoglucanase Cel5A (C) from the extreme thermophilic bacterium Fervidobacterium gondwanense and an archaeal ?-glucosidase Bgl1 (B) derived from a hydrothermal spring metagenome. Recombinant chimeras and parental enzymes were produced in Escherichia coli and purified using a two-step affinity chromatography approach. Enzymatic properties revealed that both chimeras closely resemble the parental enzymes and physical mixtures, but Cel5A displayed lower temperature tolerance at 100°C when fused to Bgl1 independent of the conformational order. Moreover, the determination of enzymatic performances resulted in the detection of additive effects in case of BC fusion chimera. Kinetic measurements in combination with HPLC-mediated product analyses and site-directed mutation constructs indicated that Cel5A was strongly impaired when fused at the N-terminus, while activity was reduced to a slighter extend as C-terminal fusion partner. In contrast to these results, catalytic activity of Bgl1 at the N-terminus was improved 1.2-fold, effectively counteracting the slightly reduced activity of Cel5A by converting cellobiose into glucose. In addition, cellobiose exhibited inhibitory effects on Cel5A, resulting in a higher yield of cellobiose and glucose by application of an enzyme mixture (53.1%) compared to cellobiose produced from endoglucanase alone (10.9%). However, the overall release of cellobiose and glucose was even increased by catalytic action of BC (59.2%). These results indicate possible advantages of easily produced bifunctional fusion enzymes for the improved conversion of complex polysaccharide plant materials. PMID:26054736

  14. Structural and biochemical characterization of a bifunctional ketoisomerase/N-acetyltransferase from Shewanella denitrificans.

    PubMed

    Chantigian, Daniel P; Thoden, James B; Holden, Hazel M

    2013-11-19

    Unusual N-acetylated sugars have been observed on the O-antigens of some Gram-negative bacteria and on the S-layers of both Gram-positive and Gram-negative bacteria. One such sugar is 3-acetamido-3,6-dideoxy-?-d-galactose or Fuc3NAc. The pathway for its production requires five enzymes with the first step involving the attachment of dTMP to glucose-1-phosphate. Here, we report a structural and biochemical characterization of a bifunctional enzyme from Shewanella denitificans thought to be involved in the biosynthesis of dTDP-Fuc3NAc. On the basis of a bioinformatics analysis, the enzyme, hereafter referred to as FdtD, has been postulated to catalyze the third and fifth steps in the pathway, namely, a 3,4-keto isomerization and an N-acetyltransferase reaction. For the X-ray analysis reported here, the enzyme was crystallized in the presence of dTDP and CoA. The crystal structure shows that FdtD adopts a hexameric quaternary structure with 322 symmetry. Each subunit of the hexamer folds into two distinct domains connected by a flexible loop. The N-terminal domain adopts a left-handed ?-helix motif and is responsible for the N-acetylation reaction. The C-terminal domain folds into an antiparallel flattened ?-barrel that harbors the active site responsible for the isomerization reaction. Biochemical assays verify the two proposed catalytic activities of the enzyme and reveal that the 3,4-keto isomerization event leads to the inversion of configuration about the hexose C-4' carbon. PMID:24128043

  15. A metal-free bifunctional electrocatalyst for oxygen reduction and oxygen evolution reactions

    NASA Astrophysics Data System (ADS)

    Zhang, Jintao; Zhao, Zhenghang; Xia, Zhenhai; Dai, Liming

    2015-05-01

    The oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) are traditionally carried out with noble metals (such as Pt) and metal oxides (such as RuO2 and MnO2) as catalysts, respectively. However, these metal-based catalysts often suffer from multiple disadvantages, including high cost, low selectivity, poor stability and detrimental environmental effects. Here, we describe a mesoporous carbon foam co-doped with nitrogen and phosphorus that has a large surface area of ?1,663?m2?g?1 and good electrocatalytic properties for both ORR and OER. This material was fabricated using a scalable, one-step process involving the pyrolysis of a polyaniline aerogel synthesized in the presence of phytic acid. We then tested the suitability of this N,P-doped carbon foam as an air electrode for primary and rechargeable Zn–air batteries. Primary batteries demonstrated an open-circuit potential of 1.48?V, a specific capacity of 735?mAh?gZn?1 (corresponding to an energy density of 835?Wh?kgZn?1), a peak power density of 55?mW?cm?2, and stable operation for 240?h after mechanical recharging. Two-electrode rechargeable batteries could be cycled stably for 180 cycles at 2?mA?cm?2. We also examine the activity of our carbon foam for both OER and ORR independently, in a three-electrode configuration, and discuss ways in which the Zn–air battery can be further improved. Finally, our density functional theory calculations reveal that the N,P co-doping and graphene edge effects are essential for the bifunctional electrocatalytic activity of our material.

  16. Bifunctional DNA Alkylator 1,3-Bis(2-chloroethyl)-1-nitrosourea Activates the ATR-Chk1 Pathway Independently of the Mismatch Repair Pathway

    PubMed Central

    Cui, B.; Johnson, S. P.; Bullock, N.; Ali-Osman, F.; Bigner, D. D.; Friedman, H. S.

    2009-01-01

    The presence of DNA damage initiates signaling through the ataxia-telangiectasia mutated kinase (ATM) and the ATM- and the Rad3-related kinase (ATR), which phosphorylate, thus activating, the checkpoint kinases (Chk) 1 and 2, which leads to cell cycle arrest. The bifunctional DNA alkylator 1,3-bis(2-chloroethyl)-1-nitrosourea (BCNU) is cytotoxic primarily by inducing DNA monoadducts and ultimately, interstrand cross-links, which block DNA replication. In this study, we investigated the activation of the ATR-Chk1 pathway in response to BCNU treatment and the dependence of this response on the DNA mismatch repair (MMR) capacity. Medulloblastoma cells were exposed to low and moderate doses of BCNU, and the effects on this DNA damage signaling pathway were examined. In response to BCNU, Chk1 was found to be phosphorylated at serine 345 and exhibited increased kinase activity. Caffeine and wortmannin, which are broad-spectrum inhibitors of ATM and ATR, reduced this phosphorylation. Cell cycle analysis further revealed an accumulation of cells in the S phase in response to BCNU, an effect that was attenuated by caffeine. Small interfering RNA knockdown of ATR also reduced Chk1 phosphorylation after exposure to BCNU. However, knockdown of ATM had no effect on the observed Chk1 phosphorylation, suggesting that ATR was primarily responsible for Chk1 activation. Analysis of Chk1 activation in cells deficient in MMR proteins MutL? or MutS? indicated that the DNA damage response induced by BCNU was independent of the MMR apparatus. This MMR-independent activation seems to be the result of DNA interstrand cross-link formation. PMID:19261750

  17. Computing Thermal Performances Of Shafts And Bearings

    NASA Technical Reports Server (NTRS)

    Woods, Claudia M.

    1992-01-01

    SHABERTH computer program developed to predict steady-state and transient thermal performance of multi-bearing shaft system operating with either wet or dry friction. Calculates loads, torques, temperatures, and fatigue lives for ball and/or roller bearings on single shaft. Enables study of many causes of instabilities in bearings. Also provides for analysis of reaction of system to termination of supply of lubricant to bearings and other lubricated mechanical elements. Valuable software tool in design and analysis of shaft bearing systems. Written in FORTRAN IV.

  18. Polar Bears International : Wrangel Island, Russia

    NSDL National Science Digital Library

    2007-12-12

    This site describes the ongoing research of the polar bears in the Russian High Arctic. Wrangel Island with neighboring small island, Herald Island, are the key reproductive areas for the Chukchi-Alaskan polar bear population. Marine areas and Wrangel and Herald islands provide optimum foraging habitats for polar bears, and polar bear densities in these marine habitats are high all year round. Approximately 350-500 pregnant female polar bears construct their maternity dens on Wrangel and Herald islands every fall, emerging with their cubs in spring. The research is described in terms of goals and objectives, structure, methods, equipment, staff, and implementations.

  19. Life of Pennzane and 815Z-Lubricated Instrument Bearings Cleaned with Non-CFC Solvents

    NASA Technical Reports Server (NTRS)

    Loewenthal, Stuart; Jones, William; Predmore, Roamer

    1999-01-01

    This report takes the form of two papers: (1) "Life of Pennzane and 815Z-Lubricated Instrument Bearings cleaned with Non-CFC Solvents" and (2) a published paper, entitled "Instrument bearing life with NON-CFC cleaners". Abstract for paper # 1 : Bearings used in spacecraft mechanisms have historically been cleaned with chlorofluorocarbon CFC-1 13 (Freon) solvents and lubricated with a perfluorinated polyalkylether (PFPE) oils like 815-Z. Little full-scale bearing life test data exists to evaluate the effects of the newer class environmental-friendly bearing cleaners or improved synthetic hydrocarbon space oils like Pennzane. To address the lack of data, a cooperative, bearing life test program was initiated between NASA, Lockheed Martin and MPB. The objective was to obtain comparative long-term, life test data for flight-quality bearings, cleaned with non-CFC solvents versus CFC-1 13 under flight-like conditions with two space oils. A goal was to gain a better understanding of the lubricant surface chemistry effects with such solvents. A second objective was to obtain well-controlled, full-scale bearing life test data with a relatively new synthetic oil (Pennzane), touted as an improvement to Bray 815Z, an oil with considerable space flight history. The second paper, which serves as an attachment, is abstracted below: Bearings used in spacecraft mechanisms have historically been cleaned with chlorofluorocarbon CFC-113 (Freon) solvents and lubricated with a perfluorinated polyalkylether (PFPE) oils like 815-Z. Little full-scale bearing life test data exists to evaluate the effects of the newer class environmental-friendly bearing cleaners or improved synthetic hydrocarbon space oils like Pennzane. To address the lack of data, a cooperative, bearing life test program was initiated between NASA, Lockheed Martin and MPB. The objective was to obtain comparative long-term, life test data for flight-quality bearings, cleaned with non-CFC solvents versus CFC-1 13 under flight-like conditions with two space oils. A goal was to gain a better understanding of the lubricant surface chemistry effects with such solvents. A second objective was to obtain well-controlled, full-scale bearing life test data with a relatively new synthetic oil (Pennzane), touted as an improvement to Bray 815Z, an oil with considerable space flight history.

  20. Test of a habitat suitability index for black bears in the southern Appalachians

    USGS Publications Warehouse

    Mitchell, M.S.; Zimmerman, J.W.; Powell, R.A.

    2002-01-01

    We present a habitat suitability index (HSI) model for black bears (Ursus americanus) living in the southern Appalachians that was developed a priori from the literature, then tested using location and home range data collected in the Pisgah Bear Sanctuary, North Carolina, over a 12-year period. The HSI was developed and initially tested using habitat and bear data collected over 2 years in the sanctuary. We increased number of habitat sampling sites, included data collected in areas affected by timber harvest, used more recent Geographic Information System (GIS) technology to create a more accurate depiction of the HSI for the sanctuary, evaluated effects of input variability on HSI values, and duplicated the original tests using more data. We found that the HSI predicted habitat selection by bears on population and individual levels and the distribution of collared bears were positively correlated with HSI values. We found a stronger relationship between habitat selection by bears and a second-generation HSI. We evaluated our model with criteria suggested by Roloff and Kernohan (1999) for evaluating HSI model reliability and concluded that our model was reliable and robust. The model's strength is that it was developed as an a priori hypothesis directly modeling the relationship between critical resources and fitness of bears and tested with independent data. We present the HSI spatially as a continuous fitness surface where potential contribution of habitat to the fitness of a bear is depicted at each point in space.

  1. Hydrostatic bearings for a turbine fluid flow metering device

    DOEpatents

    Fincke, J.R.

    1980-05-02

    A rotor assembly fluid metering device has been improved by development of a hydrostatic bearing fluid system which provides bearing fluid at a common pressure to rotor assembly bearing surfaces. The bearing fluid distribution system produces a uniform film of fluid distribution system produces a uniform film of fluid between bearing surfaces and allows rapid replacement of bearing fluid between bearing surfaces, thereby minimizing bearing wear and corrosion.

  2. Subsurface damage investigation by high frequency ultrasonic echography on 100Cr6 bearing steel

    Microsoft Academic Search

    P. Guy; P. Meynaud; A. Vincent; G. Dudragne; G. Baudry

    1997-01-01

    This paper presents an original ultrasonic technique devoted to the early detection of sub-surface fatigue cracks in 100Cr6 bearing steels. Echographic experiments were carried out during interrupted rolling contact fatigue tests. Crack initiation and crack propagation stages were both investigated. Quantitative measurements of sub-surface crack position, depth and angle with respect to the bearing surface are presented. Experimental results are

  3. Foil bearing research at Penn State

    NASA Astrophysics Data System (ADS)

    Carpino, Marc

    1993-11-01

    Foil journal bearings consist of a compliant metal shell or foil which supports a rigid journal by means of a fluid film. Foil bearings are considered to be a potential alternative to rolling element or traditional rigid surface bearings in cryogenic turbomachinery applications. The prediction of foil bearing performance requires the coupled solution of the foil deflection and the fluid flow in the bearing clearance between the rotor and the foil. The investigations being conducted in the Department of Mechanical Engineering at Penn State are focused in three areas: theoretical prediction of steady state bearing performance, modeling of the dynamic bearing characteristics to determine performance in rotor systems, and experimental verification of analysis codes. The current status and results from these efforts will be discussed.

  4. Design review of fluid film bearing testers

    NASA Technical Reports Server (NTRS)

    Scharrer, Joseph K.

    1993-01-01

    The designs of three existing testers (Hybrid Bearing Tester, OTV Bearing Tester, and Long Life Bearing Tester) owned by NASA were reviewed for their capability to serve as a multi-purpose cryogenic fluid film bearing tester. The primary tester function is the validation of analytical predictions for fluid film bearing steady state and dynamic performance. Evaluation criteria were established for test bearing configurations, test fluids, instrumentation, and test objectives. Each tester was evaluated with respect to these criteria. A determination was made of design improvements which would allow the testers to meet the stated criteria. The cost and time required to make the design changes were estimated. A recommendation based on the results of this study was made to proceed with the Hybrid Bearing Tester.

  5. Hydrostatic bearings for a turbine fluid flow metering device

    Microsoft Academic Search

    Fincke

    1980-01-01

    A rotor assembly fluid metering device has been improved by development of a hydrostatic bearing fluid system which provides bearing fluid at a common pressure to rotor assembly bearing surfaces. The bearing fluid distribution system produces a uniform film of fluid distribution system produces a uniform film of fluid between bearing surfaces and allows rapid replacement of bearing fluid between

  6. Public attitudes towards brown bears ( Ursus arctos) in Slovenia

    Microsoft Academic Search

    Petra Kaczensky; Mateja Blazic; Hartmut Gossow

    2004-01-01

    In northern Slovenia a radical change in brown bear (Ursus arctos) management – from a policy of bear suppression to a policy of bear protection – resulted in a sharp increase in sheep predation by bears. In the bear core area in southern Slovenia, on the other hand, bears have always been present, cause little damage and are an important

  7. A defined ?-helix in the bifunctional O-glycosylated natriuretic peptide TcNPa from the venom of Tropidechis carinatus.

    PubMed

    Reeks, Timothy; Jones, Alun; Brust, Andreas; Sridharan, Sindhuja; Corcilius, Leo; Wilkinson, Brendan L; Thaysen-Andersen, Morten; Payne, Richard J; Kini, R Manjunatha; Daly, Norelle L; Alewood, Paul F

    2015-04-13

    Natriuretic peptides (NP) play important roles in human cardiac physiology through their guanylyl cyclase receptors NPR-A and NPR-B. Described herein is a bifunctional O-glycosylated natriuretic peptide, TcNPa, from Tropidechis carinatus venom and it unusually targets both NPR-A and NPR-B. Characterization using specific glycosidases and ETD-MS identified the glycan as galactosyl-?(1-3)-N-acetylgalactosamine (Gal-GalNAc) and was ?-linked to the C-terminal threonine residue. TcNPa contains the characteristic NP 17-membered disulfide ring with conserved phenylalanine and arginine residues. Both glycosylated and nonglycosylated forms were synthesized by Fmoc solid-phase peptide synthesis and NMR analysis identified an ?-helix within the disulfide ring containing the putative pharmacophore for NPR-A. Surprisingly, both forms activated NPR-A and NPR-B and were relatively resistant towards proteolytic degradation in plasma. This work will underpin the future development of bifunctional NP peptide mimetics. PMID:25735823

  8. NiCo2S4@graphene as a bifunctional electrocatalyst for oxygen reduction and evolution reactions.

    PubMed

    Liu, Qiao; Jin, Jutao; Zhang, Junyan

    2013-06-12

    Here, the hybrid of NiCo2S4 nanoparticles grown on graphene in situ is first described as an effective bifunctional nonprecious electrocatalyst for oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) in the alkaline medium. NiCo2S4@N/S-rGO was synthesized by a one-pot solvothermal strategy using Co(OAc)2, Ni(OAc)2, thiourea, and graphene oxide as precursors and ethylene glycol as the dispersing agent; simultaneously, traces of nitrogen and sulfur were double-doped into the reduced graphene oxide (rGO) in the forms of pyrrolic-N, pyridinic-N, and thiophenic-S, which are often desirable for metal-free ORR catalysts. In comparison with commercial Pt/C catalyst, NiCo2S4@N/S-rGO shows less reduction activity, much better durability, and superior methanol tolerance toward ORR in 0.1 M KOH; it reveals higher activity toward OER in both KOH electrolyte and phosphate buffer at pH 7.0. NiCo2S4@graphene demonstrated excellent overall bicatalytic performance, and importantly, it suggests a novel kind of promising nonprecious bifunctional catalyst in the related renewable energy devices. PMID:23662625

  9. Mannitol-1-phosphate dehydrogenases/phosphatases: a family of novel bifunctional enzymes for bacterial adaptation to osmotic stress.

    PubMed

    Sand, Miriam; Rodrigues, Marta; González, José M; de Crécy-Lagard, Valérie; Santos, Helena; Müller, Volker; Averhoff, Beate

    2015-03-01

    The nutritionally versatile soil bacterium Acinetobacter baylyi?ADP1 copes with salt stress by the accumulation of compatible solutes, a strategy that is widespread in nature. This bacterium synthesizes the sugar alcohol mannitol de novo in response to osmotic stress. In a previous study, we identified MtlD, a mannitol-1-phosphate dehydrogenase, which is essential for mannitol biosynthesis and which catalyses the first step in mannitol biosynthesis, the reduction of fructose-6-phosphate (F-6-P) to the intermediate mannitol-1-phosphate (Mtl-1-P). Until now, the identity of the second enzyme, the phosphatase that catalyses the dephosphorylation of Mtl-1-P to mannitol, was elusive. Here we show that MtlD has a unique sequence among known mannitol-1-phosphate dehydrogenases with a haloacid dehalogenase (HAD)-like phosphatase domain at the N-terminus. This domain is indeed shown to have a phosphatase activity. Phosphatase activity is strictly Mg(2+) dependent. Nuclear magnetic resonance analysis revealed that purified MtlD catalyses not only reduction of F-6-P but also dephosphorylation of Mtl-1-P. MtlD of A.?baylyi is the first bifunctional enzyme of mannitol biosynthesis that combines Mtl-1-P dehydrogenase and phosphatase activities in a single polypeptide chain. Bioinformatic analysis revealed that the bifunctional enzyme is widespread among Acinetobacter strains but only rarely present in other phylogenetic tribes. PMID:24800891

  10. Turbocharger bearing retention and lubrication system

    SciTech Connect

    Gutknecht, D.A.

    1991-12-31

    This patent describes exhausts gas driven turbocharger. It comprises a housing, a shaft within the housing having a longitudinal axis of rotation and a pair of ends, a compressor wheel mounted within the housing on one end of the shaft for rotation therewith, a turbine wheel mounted within the housing on the other end of the shaft for rotation therewith, means for communicating air to the compressor wheel, means for communicating exhaust gas to the turbine wheel to cause the latter to rotate the shaft and the compressor wheel mounted thereon to compress the air communicated to the compressor wheel, and bearing means mounting the shaft for rotation relative to the housing, the bearing means including a bearing outer ring, a bearing inner ring, and ball bearing elements supporting the bearing outer ring on the bearing inner ring, a bearing locating aperture in the bearing outer ring, and an elongated bearing location pin having a longitudinal axis of symmetry extending transversely to the longitudinal axis of the shaft.

  11. Current Status of Hybrid Bearing Damage Detection

    NASA Technical Reports Server (NTRS)

    Dempsey, Paula J.; Certo, Joseph M.; Morales, Wilfredo

    2004-01-01

    Advances in material development and processing have led to the introduction of ceramic hybrid bearings for many applications. The introduction of silicon nitride hybrid bearings into the high pressure oxidizer turbopump, on the space shuttle main engine, led NASA to solve a highly persistent and troublesome bearing problem. Hybrid bearings consist of ceramic balls and steel races. The majority of hybrid bearings utilize Si3N4 balls. The aerospace industry is currently studying the use of hybrid bearings and naturally the failure modes of these bearings become an issue in light of the limited data available. In today s turbine engines and helicopter transmissions, the health of the bearings is detected by the properties of the debris found in the lubrication line when damage begins to occur. Current oil debris sensor technology relies on the magnetic properties of the debris to detect damage. Since the ceramic rolling elements of hybrid bearings have no metallic properties, a new sensing system must be developed to indicate the system health if ceramic components are to be safely implemented in aerospace applications. The ceramic oil debris sensor must be capable of detecting ceramic and metallic component damage with sufficient reliability and forewarning to prevent a catastrophic failure. The objective of this research is to provide a background summary on what is currently known about hybrid bearing failure modes and to report preliminary results on the detection of silicon nitride debris, in oil, using a commercial particle counter.

  12. Monitoring grizzly bear population trends

    USGS Publications Warehouse

    Eberhardt, L.L.; Knight, R.R.; Blanchard, B.M.

    1986-01-01

    A simple different equation model was developed to provide additional perspective on observed mortality and trend data on Yellowstone grizzly bears (Ursus arctos horribilis). Records of mortalities of adult females from 1959 to 1985 were utilized, in conjunction with data on females with cubs. The overall downward trend of observed numbers of females with cubs generally agrees with the model calculations but does not adequately reflect mortality from 1970 to 1974. The model may be useful in developing a composite index of population trend.

  13. Using a Bear Put Spread 

    E-print Network

    Bevers, Stan; Amosson, Stephen H.; Waller, Mark L.; Dhuyvetter, Kevin C.

    2008-10-07

    a bear put spread. In this example, assume the current Chicago Board of Trade December Corn contract is trad- ing at $6.00 per bushel. The associated December put option premiums are listed in Table 1. The producer begins the strategy by buying a... put op- tion near the money, in this case a $6.00 put op- tion for $0.90 per bushel ($4,500 per 5,000-bushel contract). At the same time, he also writes (sells) a put option with a strike price below the put option. In our example, he writes a $5...

  14. 77 FR 4993 - Certain Frozen Warmwater Shrimp From the Socialist Republic of Vietnam: Initiation and...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-02-01

    ...c)(3)(ii); see also Initiation and Preliminary Results of Antidumping Duty Changed Circumstances Review: Canned Pineapple Fruit From Thailand, 69 FR 30878 (June 1, 2004). \\16\\ See Ball Bearings and Parts Thereof from Japan: Initiation...

  15. The dual action gas thrust bearing - A new high load bearing concept

    NASA Technical Reports Server (NTRS)

    Etsion, I.

    1976-01-01

    The principle of utilizing hydrodynamic effects in diverging films for improving load capacity in gas thrust bearings is discussed. A new concept of dual action bearing based on that principle is described and analyzed. The potential of the new bearing is demonstrated both analytically for an infinitely long slider and by numerical solution for a flat sector shaped thrust bearing. It is shown that the dual action bearing can extend substantially the range of load carrying capacity in gas lubricated thrust bearings and improve their efficiency.

  16. Bifunctional RNAs Targeting the Intronic Splicing Silencer N1 Increase SMN Levels and Reduce Disease Severity in an Animal Model of Spinal Muscular Atrophy

    PubMed Central

    Osman, Erkan Y; Yen, Pei-Fen; Lorson, Christian L

    2012-01-01

    Spinal muscular atrophy (SMA) is a neurodegenerative disease caused by loss of survival motor neuron-1 (SMN1). A nearly identical copy gene, SMN2, is present in all SMA patients. Although the SMN2 coding sequence has the potential to produce full-length SMN, nearly 90% of SMN2-derived transcripts are alternatively spliced and encode a truncated protein. SMN2, however, is an excellent therapeutic target. Previously, we developed antisense-based oligonucleotides (bifunctional RNAs) that specifically recruit SR/SR-like splicing factors and target a negative regulator of SMN2 exon-7 inclusion within intron-6. As a means to optimize the antisense sequence of the bifunctional RNAs, we chose to target a potent intronic repressor downstream of SMN2 exon 7, called intronic splicing silencer N1 (ISS-N1). We developed RNAs that specifically target ISS-N1 and concurrently recruit the modular SR proteins SF2/ASF or hTra2?1. RNAs were directly injected in the brains of SMA mice. Bifunctional RNA injections were able to elicit robust induction of SMN protein in the brain and spinal column of neonatal SMA mice. Importantly, hTra2?1-ISS-N1 and SF2/ASF-ISS-N1 bifunctional RNAs significantly extended lifespan and increased weight in the SMN?7 mice. This technology has direct implications for SMA therapy and provides similar therapeutic strategies for other diseases caused by aberrant splicing. PMID:22031236

  17. Perovskite Sr0.95Ce0.05CoO3d loaded with copper nanoparticles as a bifunctional catalyst for lithium-air batteries

    E-print Network

    by a solid Li-ion electrolyte acting as a separator of an organic liquid electrolyte (anolyte) on the lithium studied as cathodes in solid oxide fuel cells operating in the temperature range 500­800 C.22 Also, Shao could be used in a metal/air battery or a PEM fuel cell as an efficient and stable bifunctional catalyst

  18. Multicolor imaging and the anticancer effect of a bifunctional silica nanosystem based on the complex of graphene quantum dots and hypocrellin A.

    PubMed

    Zhou, Lin; Zhou, Lin; Ge, Xuefeng; Zhou, Jiahong; Wei, Shaohua; Shen, Jian

    2015-01-01

    An effective theranostic platform based on porous silica nanoparticles encapsulated with the complex of a photodynamic anticancer drug and graphene quantum dots (GQDs), with the bifunction of multicolor imaging and satisfactory photo-induced anticancer activity, was successfully designed and prepared for in vitro photodynamic therapy (PDT) of superficial cancer. PMID:25407475

  19. Structural Dynamics of the Actomyosin Complex Probed by a Bifunctional Spin Label that Cross-Links SH1 and SH2

    E-print Network

    Thomas, David D.

    Structural Dynamics of the Actomyosin Complex Probed by a Bifunctional Spin Label that Cross* *Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, Minnesota showed that BSL reports the global orientation and dynamics of S1. When bound to actin in oriented muscle

  20. Small Sized EGFR1 and HER2 Specific Bifunctional Antibody for Targeted Cancer Therapy

    PubMed Central

    Ding, Li; Tian, Caiping; Feng, Song; Fida, Guissi; Zhang, Congying; Ma, Yuxiang; Ai, Guanhua; Achilefu, Samuel; Gu, Yueqing

    2015-01-01

    Targeting tumors using miniature antibodies is a novel and attractive therapeutic approach, as these biomolecules exhibit low immunogenicity, rapid clearance, and high targeting specificity. However, most of the small-sized antibodies in existence do not exhibit marked anti-tumor effects, which limit their use in targeted cancer immunotherapy. To overcome this difficulty in targeting multiple biomarkers by combination therapies, we designed a new bifunctional antibody, named MaAbNA (multivalent antibody comprised of nanobody and affibody moieties), capable of targeting EGFR1 and HER2, which are widely overexpressed in a variety of tumor types. The small-sized (29 kDa) MaAbNA, which was expressed in E.coli, consists of one anti-EGFR1 nanobody and two anti-HER2 affibodies, and possesses high affinity (KD) for EGFR1 (~4.1 nM) and HER2 (~4.7 nM). In order to enhance its anti-tumor activity, MaAbNA was conjugated with adriamycin (ADM) using a PEG2000 linker, forming a new complex anticancer drug, MaAbNA-PEG2000-ADM. MaAbNA exhibited high inhibitory effects on tumor cells over-expressing both EGFR1 and HER2, but displayed minimal cytotoxicity in cells expressing low levels of EGFR1 and HER2. Moreover, MaAbNA-PEG2000-ADM displayed increased tumoricidal effects than ADM or MaAbNA alone, as well exhibited greater antitumor efficacy than EGFR1 (Cetuximab) and HER2 (Herceptin) antibody drugs. The ability of MaAbNA to regulate expression of downstream oncogenes c-jun, c-fos, c-myc, as well as AEG-1 for therapeutic potential was evaluated by qPCR and western-blot analyses. The antitumor efficacy of MaAbNA and its derivative MaAbNA-PEG2000-ADM were validated in vivo, highlighting the potential for use of MaAbNA as a highly tumor-specific dual molecular imaging probe and targeted cancer therapeutic. PMID:25699098

  1. Idiosyncratic responses of grizzly bear habitat to climate change based on projected food resource changes.

    PubMed

    Roberts, David R; Nielsen, Scott E; Stenhouse, Gordon B

    2014-07-01

    Climate change vulnerability assessments for species of conservation concern often use species distribution and ecological niche modeling to project changes in habitat. One of many assumptions of these approaches is that food web dependencies are consistent in time and environmental space. Species at higher trophic levels that rely on the availability of species at lower trophic levels as food may be sensitive to extinction cascades initiated by changes in the habitat of key food resources. Here we assess climate change vulnerability for Ursus arctos (grizzly bears) in the southern Canadian Rocky Mountains using projected changes to 17 of the most commonly consumed plant food items. We used presence-absence information from 7088 field plots to estimate ecological niches and to project changes in future distributions of each species. Model projections indicated idiosyncratic responses among food items. Many food items persisted or even increased, although several species were found to be vulnerable based on declines or geographic shifts in suitable habitat. These included Hedysarum alpinum (alpine sweet vetch), a critical spring and autumn root-digging resource when little else is available. Potential habitat loss was also identified for three fruiting species of lower importance to bears: Empetrum nigrum (crowberry), Vaccinium scoparium (grouseberry), and Fragaria virginiana (strawberry). A general trend towards uphill migration of bear foods may result in higher vulnerability to bear populations at low elevations, which are also those that are most likely to have human-bear conflict problems. Regardless, a wide diet breadth of grizzly bears, as well as wide environmental niches of most food items, make climate change a much lower threat to grizzly bears than other bear species such as polar bears and panda bears. We cannot exclude, however, future alterations in human behavior and land use resulting from climate change that may reduce survival rates. PMID:25154102

  2. Magnetic bearings - State of the art

    NASA Technical Reports Server (NTRS)

    Fleming, David P.

    1993-01-01

    Magnetic bearings have existed for many years, at least in theory. Earnshaw's theorem, formulated in 1842, concerns stability of magnetic suspensions, and states that not all axes of a bearing can be stable without some means of active control. In Beam's widely referenced experiments, a tiny (1/64 in diameter) rotor was rotated to the astonishing speed of 800,000 rps while it was suspended in a magnetic field. Despite a long history, magnetic bearings have only begun to see practical application since about 1980. The development that finally made magnetic bearings practical was solid state electronics, enabling power supplies and controls to be reduced in size to where they are now comparable in volume to the bearings themselves. An attempt is made to document the current (1991) state of the art of magnetic bearings. The referenced papers are large drawn from two conferences publications published in 1988 and 1990 respectively.

  3. Magnetic bearings-state of the art

    NASA Technical Reports Server (NTRS)

    Fleming, David P.

    1991-01-01

    Magnetic bearings have existed for many years, at least in theory. Earnshaw's theorem, formulated in 1842, concerns stability of magnetic suspensions, and states that not all axes of a bearing can be stable without some means of active control. In Beam's widely referenced experiments, a tiny (1/64 in diameter) rotor was rotated to the astonishing speed of 800,000 rps while it was suspended in a magnetic field. Despite a long history, magnetic bearings have only begun to see practical application since about 1980. The development that finally made magnetic bearings practical was solid state electronics, enabling power supplies and controls to be reduced in size to where they are now comparable in volume to the bearings themselves. An attempt is made to document the current (1991) state of the art of magnetic bearings. The referenced papers are large drawn from two conferences publications published in 1988 and 1990 respectively.

  4. Effect of Rolling Bearing Refurbishment and Restoration on Bearing Life and Reliability

    NASA Technical Reports Server (NTRS)

    Zaretsky, Erwin V.; Branzai, Emanuel V.

    2005-01-01

    For nearly four decades it has been a practice in commercial and military aircraft application that rolling-element bearings removed at maintenance or overhaul be reworked and returned to service. The work presented extends previously reported bearing life analysis to consider the depth (Z(45)) to maximum shear stress (45) on stressed volume removal and the effect of replacing the rolling elements with a new set. A simple algebraic relationship was established to determine the L(10) life of bearing races subject to bearing rework. Depending on the extent of rework and based upon theoretical analysis, representative life factors (LF) for bearings subject to rework ranged from 0.87 to 0.99 the lives of new bearings. Based on bearing endurance data, 92 percent of the bearing sets that would be subject to rework would result in L(10) lives equaling and/or exceeding that predicted for new bearings with the remaining 8 percent having the potential to achieve the analytically predicted life of new bearings when one of the rings is replaced at rework.. The potential savings from bearing rework varies from 53 to 82 percent that of new bearings depending on the cost, size and complexity of the bearing.

  5. Contrasting past and current numbers of bears visiting Yellowstone cutthroat trout streams

    USGS Publications Warehouse

    Haroldson, Mark A.; Schwartz, Charles C.; , JUSTIN E. TEISBERG; , Kerry A. Gunther; , JENNIFER K. FORTIN; , CHARLES T. ROBBINS

    2014-01-01

    Spawning cutthroat trout (Oncorhynchus clarkii bouvieri) were historically abundant within tributary streams of Yellowstone Lake within Yellowstone National Park and were a highly digestible source of energy and protein for Yellowstone’s grizzly bears (Ursus arctos) and black bears (U. americanus). The cutthroat trout population has subsequently declined since the introduction of non-native lake trout (Salvelinus namaycush), and in response to effects of drought and whirling disease (Myxobolus cerebralis). The trout population, duration of spawning runs, and indices of bear use of spawning streams had declined in some regions of the lake by 1997–2000. We initiated a 3-year study in 2007 to assess whether numbers of spawning fish, black bears, and grizzly bears within and alongside stream corridors had changed since 1997– 2000. We estimated numbers of grizzly bears and black bears by first compiling encounter histories of individual bears visiting 48 hair-snag sites along 35 historically fished streams.We analyzed DNA encounter histories with Pradel-recruitment and Jolly-Seber (POPAN) capture-mark-recapture models. When compared to 1997–2000, the current number of spawning cutthroat trout per stream and the number of streams with cutthroat trout has decreased. We estimated that 48 (95% CI¼42–56) male and 23 (95% CI¼21–27) female grizzly bears visited the historically fished tributary streams during our study. In any 1- year, 46 to 59 independent grizzly bears (8–10% of estimated Greater Yellowstone Ecosystem population) visited these streams. When compared with estimates from the 1997 to 2000 study and adjusted for equal effort, the number of grizzly bears using the stream corridors decreased by 63%. Additionally, the number of black bears decreased between 64% and 84%. We also document an increased proportion of bears of both species visiting front-country (i.e., near human development) streams. With the recovery of cutthroat trout, we suggest bears that still reside within the Lake basin will readily use this high-quality food resource.

  6. Quantifying oil filtration effects on bearing life

    Microsoft Academic Search

    W. M. Needelman; E. V. Zaretsky

    1991-01-01

    Rolling-element bearing life is influenced by the number, size, and material properties of particles entering the Hertzian contact of the rolling element and raceway. In general, rolling-element bearing life increases with increasing level of oil filtration. Based upon test results, two equations are presented which allow for the adjustment of bearing Lââ or catalog life based upon oil filter rating.

  7. Notes 16. Analysis of tilting pad bearings 

    E-print Network

    San Andres, Luis

    2010-01-01

    NOTES 16. STATIC AND DYNAMIC FORCED PERFORMANCE OF TILTING PAD BEARINGS: ANALYSIS INCLUDING PIVOT STIFFNESS Dr. Luis San Andr?s Mast-Childs Professor August 2010 SUMMARY Work in progress ? still a lot of be done Introduction... Figure 1 shows a tilting pad journal bearing comprised of four pads. Each pad tilts about its pivot making a hydrodynamic film that generates a pressure reacting to the static load applied on the spinning journal. This type of bearing is typically...

  8. Cantilever mounted resilient pad gas bearing

    NASA Technical Reports Server (NTRS)

    Etsion, I. (inventor)

    1978-01-01

    A gas-lubricated bearing is described, employing at least one pad mounted on a rectangular cantilever beam to produce a lubricating wedge between the face of the pad and a moving surface. The load-carrying and stiffness characteristics of the pad are related to the dimensions and modulus of elasticity of the beam. The bearing is applicable to a wide variety of types of hydrodynamic bearings.

  9. Hybrid air foil bearing with external pressurization

    E-print Network

    Park, Soongook

    2009-05-15

    . Heshmat [8], calculated load carrying capacity using Finite Difference (FD) and Finite Element (FE) Method for better design of foil bearings. Peng and Khonsari [9] presented thermohydrodynamic analyses on temperature distribution of the air film... and compared with experimental results. DellaCorte [10] presented a rule of thumb-based analytical formula predicting comparative load capacities of various air foil bearings, and provides design guidelines of air foil bearing. Kim and San Andr?s [11...

  10. Static forces in a superconducting magnet bearing

    SciTech Connect

    Stoye, P.; Fuchs, G. [Institut fuer Festkoerper- und Werkstofforschung, Dresden (Germany)] [Institut fuer Festkoerper- und Werkstofforschung, Dresden (Germany); Gawalek, W.; Goernert, P. [Institut fuer Physikalische Hochtechnologie, Jena (Germany)] [Institut fuer Physikalische Hochtechnologie, Jena (Germany); Gladun, A. [Technische Univ., Dresden (Germany)] [Technische Univ., Dresden (Germany)

    1995-11-01

    Static levitation forces and stiffnesses in a superconducting bearing consisting of concentric ring magnets and a superconducting YBaCuO ring are investigated. In the field-cooled mode a levitation force of 20 N has been achieved. The axial and radial stiffnesses have values of 15 N/mm and 10 N/mm, respectively. An arrangement with two bearings supporting a high speed shaft is now under development. A possible application of superconducting magnetic bearings is flywheels for energy storage.

  11. Development Initiatives

    NSDL National Science Digital Library

    Development Initiatives is an English independent organization focusing on issues of poverty, aid, development, and international relations. Updated regularly, the Development Initiatives Website contains the organization's reactions to development policy and links and commentary on other agencies' reports. The site also contains detailed information on the Finance and Development Research Programme including an extensive collection of working papers, newsletters, and links and related literature. Also included on the site are articles from the Development Initiatives' publication, Reality of Aid, an "independent review of poverty reduction and development assistance." Although the site's navigation is a little bit disorganized, it is well worth some exploration by those interested in development issues.

  12. Synthesis of bifunctional molecules containing [12]aneN3 and coumarin moieties as effective DNA condensation agents and new non-viral gene vectors.

    PubMed

    Yue, Pan; Zhang, Ying; Guo, Zhi-Fo; Cao, Ao-Cheng; Lu, Zhong-Lin; Zhai, Yong-Gong

    2015-04-21

    A series of bifunctional molecules with different combinations of macrocyclic polyamine [12]aneN3 and coumarin moieties, 4a/b and 5a/b, were synthesized by a two-step copper(I)-mediated alkyne–azide click reactions between 1,3,5-tris(azidomethyl)benzene and Boc-protected N-propynyl-[12]aneN3/7-propynyloxycoumarins. Agarose gel electrophoresis experiments indicated that bifunctional molecules 4b and 5b effectively induced complete plasmid DNA condensation at concentrations up to 40 ?M. It was found that the structural variation had a major impact on the condensation behavior of these compounds. The electrostatic interaction involving the [12]aneN3 moiety can be compensated by the binding contribution of the coumarin units during the DNA condensation process. These two types of interaction showed different effects on the reversibility of DNA condensation. Results from studies using dynamic laser scattering, atomic force microscopy, and EB replacement assay further supported the above conclusion. Cytotoxicity assays on bifunctional compounds 4a/b and 5a/b indicated their low cytotoxicity. Results from cellular uptake and cell transfection experiments proved that bifunctional compounds 4b and 5b successfully served as non-viral gene vectors. Furthermore, methyl substituents attached to the coumarin unit (4b and 5b) greatly enhanced their DNA condensation capability and gene transfection. These bifunctional molecules, with the advantages of lower cytotoxicity, good water solubility, and potential structural modification, will have great potential for the development of new non-viral gene delivery agents. PMID:25772225

  13. Fractional Whirl Motion in Wave Journal Bearings

    NASA Technical Reports Server (NTRS)

    Dimofte, Florin; Hendricks, Robert C.

    1996-01-01

    Unloaded gas, plain journal bearings experience sub-synchronous whirl motion due to fluid film instabilities and wall contact usually occurs immediately after the onset of the whirl motion. An alternative is the wave journal bearing which significantly improves bearing stability. The predicted threshold where the sub-synchronous whirl motion starts was well confirmed by the experimental observation. In addition, both a two-wave and a three-wave journal bearing can operate free of sub-synchronous whirl motion over a large range in speeds. When the sub-synchronous whirl motion occurs, both the two-wave and three-wave bearing can run in a whirl orbit well within the bearing clearance. At large clearances and wave amplitudes a two-wave bearing, unliKe other bearings, can exhibit a sub-synchronous whirl movement at both low and high speeds, but can run extremely stable and without whirl at intermediate speeds. Moreover, in these cases, the whirl frequencies are close to a quarter of the synchronous speed. The three-wave bearing can exhibit sub-synchronous whirl motion only after a specific threshold when the speed increases and the whirl frequencies are close to half of the synchronous speed.

  14. Polar Bears International: Vital Maternity Den Study

    NSDL National Science Digital Library

    This report describes a journalist's participation in a study of polar bear denning sites in the Alaska National Wildlife Refuge (ANWR). It is thought that cubs born in those dens play an important role in maintaining the Beaufort Sea population of polar bears. Prior to the study, no complete map existed pinpointing the ANWR's denning areas. The study data will be available to manage human activities, thus protecting the sensitive areas in which a mother polar bear may den. The study will also provide baseline data to assess how climate change may alter the distribution of polar-bear denning habitat.

  15. 63 FR 40878 - Antifriction Bearings (Other Than Tapered Roller Bearings) and Parts Thereof From Italy, Romania...

    Federal Register 2010, 2011, 2012, 2013, 2014

    1998-07-31

    ...Bearings) and Parts Thereof From Italy, Romania, and the United Kingdom; Amended Final...from France, Germany, Italy, Japan, Romania, Singapore, Sweden, and the United...with regard to ball bearings from Italy, Romania and the United Kingdom. Based on...

  16. Dynamic modelling and response characteristics of a magnetic bearing rotor system including auxiliary bearings

    NASA Technical Reports Server (NTRS)

    Free, April M.; Flowers, George T.; Trent, Victor S.

    1993-01-01

    Auxiliary bearings are a critical feature of any magnetic bearing system. They protect the soft iron core of the magnetic bearing during an overload or failure. An auxiliary bearing typically consists of a rolling element bearing or bushing with a clearance gap between the rotor and the inner race of the support. The dynamics of such systems can be quite complex. It is desired to develop a rotor-dynamic model and assess the dynamic behavior of a magnetic bearing rotor system which includes the effects of auxiliary bearings. Of particular interest is the effects of introducing sideloading into such a system during failure of the magnetic bearing. A model is developed from an experimental test facility and a number of simulation studies are performed. These results are presented and discussed.

  17. Dynamic modelling and response characteristics of a magnetic bearing rotor system with auxiliary bearings

    NASA Technical Reports Server (NTRS)

    Free, April M.; Flowers, George T.; Trent, Victor S.

    1995-01-01

    Auxiliary bearings are a critical feature of any magnetic bearing system. They protect the soft iron core of the magnetic bearing during an overload or failure. An auxiliary bearing typically consists of a rolling element bearing or bushing with a clearance gap between the rotor and the inner race of the support. The dynamics of such systems can be quite complex. It is desired to develop a rotordynamic model which describes the dynamic behavior of a flexible rotor system with magnetic bearings including auxiliary bearings. The model is based upon an experimental test facility. Some simulation studies are presented to illustrate the behavior of the model. In particular, the effects of introducing sideloading from the magnetic bearing when one coil fails is studied.

  18. Dynamic modelling and response characteristics of a magnetic bearing rotor system with auxiliary bearings

    NASA Astrophysics Data System (ADS)

    Free, April M.; Flowers, George T.; Trent, Victor S.

    1995-06-01

    Auxiliary bearings are a critical feature of any magnetic bearing system. They protect the soft iron core of the magnetic bearing during an overload or failure. An auxiliary bearing typically consists of a rolling element bearing or bushing with a clearance gap between the rotor and the inner race of the support. The dynamics of such systems can be quite complex. It is desired to develop a rotordynamic model which describes the dynamic behavior of a flexible rotor system with magnetic bearings including auxiliary bearings. The model is based upon an experimental test facility. Some simulation studies are presented to illustrate the behavior of the model. In particular, the effects of introducing sideloading from the magnetic bearing when one coil fails is studied.

  19. Dynamic modelling and response characteristics of a magnetic bearing rotor system including auxiliary bearings

    NASA Astrophysics Data System (ADS)

    Free, April M.; Flowers, George T.; Trent, Victor S.

    Auxiliary bearings are a critical feature of any magnetic bearing system. They protect the soft iron core of the magnetic bearing during an overload or failure. An auxiliary bearing typically consists of a rolling element bearing or bushing with a clearance gap between the rotor and the inner race of the support. The dynamics of such systems can be quite complex. It is desired to develop a rotor-dynamic model and assess the dynamic behavior of a magnetic bearing rotor system which includes the effects of auxiliary bearings. Of particular interest is the effects of introducing sideloading into such a system during failure of the magnetic bearing. A model is developed from an experimental test facility and a number of simulation studies are performed. These results are presented and discussed.

  20. Socioeconomic issues for the Bear River Watershed Conservation Land Area Protection Plan

    USGS Publications Warehouse

    Thomas, Catherine Cullinane; Huber, Christopher; Gascoigne, William; Koontz, Lynne

    2012-01-01

    The Bear River Watershed Conservation Area is located in the Bear River Watershed, a vast basin covering fourteen counties across three states. Located in Wyoming, Utah, and Idaho, the watershed spans roughly 7,500 squares miles: 1,500 squares miles in Wyoming; 2,700 squares miles in Idaho; and 3,300 squares miles in Utah (Utah Division of Water Resources, 2004). Three National Wildlife Refuges are currently contained within the boundary of the BRWCA: the Bear River Migratory Bird Refuge in Utah, the Bear Lake National Wildlife Refuge in Idaho, and the Cokeville Meadows National Wildlife Refuge in Wyoming. In 2010, the U.S. Fish and Wildlife Service conducted a Preliminary Project Proposal and identified the Bear River Watershed Conservation Area as having high-value wildlife habitat. This finding initiated the Land Protection Planning process, which is used by the U.S. Fish and Wildlife Service to study land conservation opportunities including adding lands to the National Wildlife Refuge System. The U.S. Fish and Wildlife Service proposes to include part of the Bear River Watershed Conservation Area in the Refuge System by acquiring up to 920,000 acres of conservation easements from willing landowners to maintain landscape integrity and habitat connectivity in the region. The analysis described in this report provides a profile of the social and economic conditions in the Bear River Watershed Conservation Area and addresses social and economic questions and concerns raised during public involvement in the Land Protection Planning process.

  1. Evaluation of bearing configurations using the single bearing tester in liquid nitrogen

    NASA Technical Reports Server (NTRS)

    Jett, T.; Hall, P.; Thom, R.

    1991-01-01

    Various bearing configurations were tested using the Marshall Space Flight Center single bearing tester with LN2 as the cryogenic coolant. The baseline was one Rocketdyne phase one high pressure oxidizer turbopump (HPOTP) pump end 45-mm bore bearing. The bearing configurations that were tested included a Salox/M cage configuration, a silicon nitride ball configuration, an elongated cage configuration, and a Bray 601 grease configuration.

  2. 61 FR 60679 - Antifriction Bearings (Other than Tapered Roller Bearings) and Parts Thereof from Romania...

    Federal Register 2010, 2011, 2012, 2013, 2014

    1996-11-29

    ...Roller Bearings) and Parts Thereof from Romania; Preliminary Results of Antidumping Duty...bearings) and parts thereof (AFBs), from Romania. The review covers shipments of the subject...on ball bearings and parts thereof from Romania. On June 22, 1994 (59 FR...

  3. 62 FR 32292 - Antifriction Bearings (Other Than Tapered Roller Bearings) and Parts Thereof From Romania; Final...

    Federal Register 2010, 2011, 2012, 2013, 2014

    1997-06-13

    ...Roller Bearings) and Parts Thereof From Romania; Final Results of Antidumping Duty Administrative...bearings) and parts thereof (AFBs), from Romania. The period of review (POR) is May...duty order on BBs and parts thereof from Romania. See Antifriction Bearings (Other...

  4. Unbalance Response Prediction for Rotors on Ball Bearings Using Speed and Load Dependent Nonlinear Bearing Stiffness

    NASA Technical Reports Server (NTRS)

    Fleming, David P.; Poplawski, J. V.

    2003-01-01

    Rolling-element bearing forces vary nonlinearly with bearing deflection. Thus an accurate rotordynamic analysis requires that bearing forces corresponding to the actual bearing deflection be utilized. For this work bearing forces were calculated by COBRA-AHS, a recently developed rolling-element bearing analysis code. Bearing stiffness was found to be a strong function of bearing deflection, with higher deflection producing markedly higher stiffness. Curves fitted to the bearing data for a range of speeds and loads were supplied to a flexible rotor unbalance response analysis. The rotordynamic analysis showed that vibration response varied nonlinearly with the amount of rotor imbalance. Moreover, the increase in stiffness as critical speeds were approached caused a large increase in rotor and bearing vibration amplitude over part of the speed range compared to the case of constant bearing stiffness. Regions of bistable operation were possible, in which the amplitude at a given speed was much larger during rotor acceleration than during deceleration. A moderate amount of damping will eliminate the bistable region, but this damping is not inherent in ball bearings.

  5. Remote Detection of Bearing Fatigue Spalls via the Dynamic Response of Bearings on the Same Shaft

    Microsoft Academic Search

    David Tow; Sean Marble

    2007-01-01

    Turbine engine bearing failures are the leading mechanical cause of class-A failures. The most common mode of bearing failure in turbine engine applications is fatigue spalling. This paper describes a sensor capable of monitoring multiple bearings on a common shaft for the presence of fatigue spalls. Experimental data is presented demonstrating the ability of a single sensor installed on one

  6. Active hydrostatic bearing with magnetorheological fluid

    NASA Astrophysics Data System (ADS)

    Hesselbach, J.; Abel-Keilhack, C.

    2003-05-01

    Special bearings based on magnetic fluids are well known in literature. These bearings use the magnetic pressure inside a ferrofluid that is exposed to a magnetic field. The biggest disadvantage of this principle is the small load that can be supported. In one reference [B. M. Berkovsky, V. F. Medvedev, and M. S. Krakov, Magnetic Fluids, Engineering Applications (Oxford University Press, Oxford, 1993)], the specific load is specified as 1 N cm-2. To support heavy loads very large support areas are needed. We will present a completely different concept for bearings with magnetorheological fluids. Hydrostatic bearings get their load bearing capacity from the hydrostatic pressure produced by an external pump and should not be confused with hydrodynamic bearings presented in another reference [R. Patzwald, M. S. thesis, Institute für Werkzeugmaschinen und Fabrikbetrieb, Technische Universität, Berlin (2001)]. The main disadvantage of hydrostatic bearings is that the bearing gap varies with the payload. Conventional systems compensate for these variations with a change of the oil flow rate, that is done, for example, by external valves. Our contribution will present a hydrostatic bearing that uses magnetorheological fluids. Due to the fact that magnetorheological fluids change their rheological properties with the change of an external magnetic field, it is possible to achieve a constant bearing gap even if the payload changes. The great advantage of this system compared to valve based systems is the short response time to payload changes, because the active element (i.e., the fluid) acts directly inside the bearing gap, and not outside like in the case of valves.

  7. Universal surface-initiated polymerization of antifouling zwitterionic brushes using a mussel-mimetic peptide initiator.

    PubMed

    Kuang, Jinghao; Messersmith, Phillip B

    2012-05-01

    We report a universal method for the surface-initated polymerization (SIP) of an antifouling polymer brush on various classes of surfaces, including noble metals, metal oxides, and inert polymers. Inspired by the versatility of mussel adhesive proteins, we synthesized a novel bifunctional tripeptide bromide (BrYKY) that combines atom-transfer radical polymerization (ATRP) initiating alkyl bromide with l-3,4-dihydroxyphenylalanine (DOPA) and lysine. The simple dip-coating of substrates with variable wetting properties and compositions, including Teflon, in a BrYKY solution at pH 8.5 led to the formation of a thin film of cross-linked BrYKY. Subsequently, we showed that the BrYKY layer initiated the ATRP of a zwitterionic monomer, sulfobetaine methacrylate (SBMA), on all substrates, resulting in high-density antifouling pSBMA brushes. Both BrYKY deposition and pSBMA grafting were unambiguously confirmed by ellipsometry, X-ray photoelectron spectroscopy, and goniometry. All substrates that were coated with BrYKY/pSBMA dramatically reduced bacterial adhesion for 24 h and also resisted mammalian cell adhesion for at least 4 months, demonstrating the long-term stability of the BrYKY anchoring and antifouling properties of pSBMA. The use of BrYKY as a primer and polymerization initiator has the potential to be widely employed in surface-grafted polymer brush modifications for biomedical and other applications. PMID:22506651

  8. Universal Surface-initiated Polymerization of Antifouling Zwitterionic Brushes Using A Mussel-Mimetic Peptide Initiator

    PubMed Central

    Kuang, Jinghao; Messersmith, Phillip B.

    2012-01-01

    We report a universal method for the surface-initated polymerization (SIP) of a antifouling polymer brush on various classes of surfaces, including noble metals, metal oxides and inert polymers. Inspired by the versatility of mussel adhesive proteins, we synthesized a novel bifunctional tripeptide bromide (BrYKY) which combines an atom transfer radical polymerization (ATRP) initiating alkyl bromide with l-3,4-dihydroxyphenylalanine (DOPA) and lysine. Simple dip-coating of substrates with variable wetting properties and compositions, including Teflon®, in a BrYKY solution at pH 8.5 led to formation of a thin film of cross-linked BrYKY. Subsequently, we showed that the BrYKY layer initiated the ATRP of a zwitterionic monomer, sulfobetaine methacrylate (SBMA) on all substrates, resulting in high density antifouling pSBMA brushes. Both BrYKY deposition and pSBMA grafting were unambiguously confirmed by ellipsometry, X-ray photoelectron spectroscopy and goniometry. All substrates that were coated with BrYKY/pSBMA dramatically reduced bacterial adhesion for 24 h and also resisted mammalian cell adhesion for at least 4 months, demonstrating the long-term stability of the BrYKY anchoring and antifouling properties of pSBMA. The use of BrYKY as a primer and polymerization initiator has the potential to be widely employed in surface grafted polymer brush modifications for biomedical and other applications. PMID:22506651

  9. Grizzly Bear Creek Flooding May 2015, SD

    USGS Multimedia Gallery

    Grizzly Bear Creek in Keystone, SD, on May 24, 2015. USGS streamgage 06403850 (Grizzly Bear Creek near Keystone, SD) showed the creek was more than one-half foot above flood stage on May 24. This streamgage is operated in cooperation with the METWARN (Rapid City/Pennington County Emer...

  10. Methods and systems for micro bearings

    DOEpatents

    Stalford, Harold L.

    2012-10-09

    A micro drive assembly may comprise a substrate, a micro shall oriented in-plane with the substrate and at least one micro bearing to support rotation of the micro shaft. The micro shaft and micro bearing may be in or less than the micrometer domain.

  11. Air-Bearing Table for Machine Shops

    NASA Technical Reports Server (NTRS)

    Ambrisco, D.

    1986-01-01

    Frequent workpiece repositioning made easier. Air-bearing table facilitates movement of heavy workpiece during machining or between repeated operations at different positions. Table assembly consists of workpiece supporting fixture riding on air bearing. Table especially useful for inertia welding, in which ease of mobility is important.

  12. Electrorheological fluid-controlled 'smart' journal bearings

    NASA Astrophysics Data System (ADS)

    Dimarogonas, Andrew D.; Kollias, Alexander

    1992-10-01

    The controllability of the stability properties of electrorheological (ER) fluid bearings is investigated using a specially developed solution of the lubricating equation for ER fluids. It was found that the properties of ER fluid bearings can be changed considerably by an applied electric field and that the stability region can be extended substantially.

  13. Pneumatic power is transmitted through air bearing

    NASA Technical Reports Server (NTRS)

    Johnson, H. I.; Wobig, O. A.

    1964-01-01

    A more efficient method for supplying high pressure air to an air bearing and pneumatic equipment mounted on it has been developed. The system uses a conventional air bearing and an air-supported sphere with a central passage. High pressure air is channeled through it into the pneumatic equipment on the sphere.

  14. Self-adjusting magnetic bearing systems

    DOEpatents

    Post, R.F.

    1998-07-21

    A self-adjusting magnetic bearing automatically adjusts the parameters of an axially unstable magnetic bearing such that its force balance is maintained near the point of metastable equilibrium. Complete stabilization can be obtained with the application of weak restoring forces either from a mechanical bearing (running at near-zero load, thus with reduced wear) or from the action of residual eddy currents in a snubber bearing. In one embodiment, a torque is generated by the approach of a slotted pole to a conducting plate. The torque actuates an assembly which varies the position of a magnetic shunt to change the force exerted by the bearing. Another embodiment achieves axial stabilization by sensing vertical displacements in a suspended bearing element, and using this information in an electrical servo system. In a third embodiment, as a rotating eddy current exciter approaches a stationary bearing, it heats a thermostat which actuates an assembly to weaken the attractive force between the two bearing elements. An improved version of an electromechanical battery utilizing the designs of the various embodiments is described. 7 figs.

  15. The greening of polar bears in zoos

    Microsoft Academic Search

    Ralph A. Lewin

    1979-01-01

    POLAR BEARS (Thalarctos maritimus) normally have creamy-white fur, presumably an adaptation for camouflage in a snowy environment. However, during the summer of 1978, the fur on the back and sides of three adults in the San Diego Zoo turned green, though the animals remained otherwise healthy. (Of these bears, one female was born in the zoo in Calgary, Alberta, Canada,

  16. A flexible cruciform journal bearing mount

    NASA Technical Reports Server (NTRS)

    Frost, A. E.; Geiger, W. A.

    1973-01-01

    Flexible mount achieves low roll, pitch and yaw stiffnesses while maintaining high radial stiffness by holding bearing pad in fixed relationship to deep web cruciform member and holding this member in fixed relationship to bearing support. This mount has particular application in small, high performance gas turbines.

  17. Characteristics of shaft voltage and bearing currents

    Microsoft Academic Search

    D. Busse; J. Erdman; R. Kerkman; D. Schlegel; G. Skibinski

    1997-01-01

    This article reviews investigations into reduced bearing life due to voltage source adjustable speed drive (ASD) AC motor operation. Relevant bearing failure mechanisms and indicators are discussed. dv\\/dt and electric discharge machining (EDM) contributions are discussed and experimental data presented showing the voltage levels on motor shafts when operating with ASDs. Finally, techniques to reduce shaft voltage are discussed, along

  18. Measuring Bearing Wear Via Weight Loss

    NASA Technical Reports Server (NTRS)

    Keba, John E.; Moore, Richard S.

    1989-01-01

    Wear in critical parts of bearings measured via amounts of weight lost during use. Technique applicable in general to bearings made of nonporous materials. Weight-loss measurements easier, faster, more precise, and less likely to damage measured parts. Weight-loss measurements performed in clean rooms and under constraint of extreme cleanliness for compatability with liquid oxygen.

  19. The Bearing Strength of Fiber Metal Laminates

    Microsoft Academic Search

    R. G. J. Van Rooijen; J. Sinke; T. J. De Vries; S. Van Der Zwaag

    2006-01-01

    The bearing strength, in particular the edge distance sensitivity, of several fiber metal laminates of the GLARE family is experimentally evaluated. The behavior of the fiber layer is investigated in detail to obtain a better understanding of its failure mode. Parallel with these experiments, the bearing behavior is studied using a finite element (FE) model. The plasticity in the metal

  20. Corrosion of plain bearings in diesel engines

    Microsoft Academic Search

    B. M. Bunakov; G. P. Belyanchikov; A. L. Chudinovskikh; M. A. Grigorev

    1983-01-01

    The serviceability of plain bearings depends on many factors, in particular the engine operating temperatures and loads, the bearing design and conditions of assembly, the type of antifriction layer and break-in coating, the design features of the engine lubrication system, and the quality of the engine oil. Demonstrates that the corrosivity of modern oils for high-performance diesel engines depends on

  1. Computing Flows In Turbine End Bearings

    NASA Technical Reports Server (NTRS)

    Smith, Tyn S.

    1990-01-01

    Computer program implements mathematical model of flow through turbine and bearings of high-pressure-oxygen turbopump of Space Shuttle main engine. Intended to determine rate of flow and margin before vaporization in these bearings for various types of geometries. Effects of hydrostatic damper and/or back-pressure seal included. Modified for application to other turbomachines and fluids other than oxygen.

  2. Precision instrumentation for rolling element bearing characterization

    SciTech Connect

    Marsh, Eric R.; Vigliano, Vincent C.; Weiss, Jeffrey R.; Moerlein, Alex W.; Vallance, R. Ryan [Machine Dynamics Research Laboratory, Pennsylvania State University, 331 Reber Building University Park, Pennsylvania 16802 (United States); Precision Systems Laboratory, George Washington University, 738 Phillips Hall 801 22nd Street, N.W. Washington, D.C., 20052 (United States)

    2007-03-15

    This article describes an instrument to measure the error motion of rolling element bearings. This challenge is met by simultaneously satisfying four requirements. First, an axial preload must be applied to seat the rolling elements in the bearing races. Second, one of the races must spin under the influence of an applied torque. Third, rotation of the remaining race must be prevented in a way that leaves the radial, axial/face, and tilt displacements free to move. Finally, the bearing must be fixtured and measured without introducing off-axis loading or other distorting influences. In the design presented here, an air bearing reference spindle with error motion of less than 10 nm rotates the inner race of the bearing under test. Noninfluencing couplings are used to prevent rotation of the bearing outer race and apply an axial preload without distorting the bearing or influencing the measurement. Capacitive displacement sensors with 2 nm resolution target the nonrotating outer race. The error motion measurement repeatability is shown to be less than 25 nm. The article closes with a discussion of how the instrument may be used to gather data with sufficient resolution to accurately estimate the contact angle of deep groove ball bearings.

  3. CHANGES IN MORTALITY OF YELLOWSTONE'S GRIZZLY BEARS

    Microsoft Academic Search

    DAVID J. MATTSON

    Records of grizzly bear (Ursus arctos) deaths are currently used by managers to indicate trends in actual grizzly bear mortality and to judge the effectiveness of management. Two assumptions underlie these current uses: first, that recorded mortality is an unbiased indicator of actual mortality, and second, that changes in mortality after implementation of management strategies are sufficient grounds to infer

  4. Diffusion of Water with Gummy Bears

    NSDL National Science Digital Library

    Mary Harris

    2003-01-01

    In this activity, learners investigate the movement of water into and out of a polymer. Learners test the diffusion of water through gummy bears, which are made of sugar and gelatin (a polymer). Learners compare what happens when gummy bears are submerged in tap water versus distilled water.

  5. 33 CFR 117.543 - Bear Creek.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ...Navigable Waters 1 2010-07-01 2010-07-01 false Bear Creek. 117.543 Section 117.543 Navigation and Navigable...REGULATIONS Specific Requirements Maryland § 117.543 Bear Creek. (a) The draws of the Baltimore County...

  6. 33 CFR 117.543 - Bear Creek.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ...Navigable Waters 1 2011-07-01 2011-07-01 false Bear Creek. 117.543 Section 117.543 Navigation and Navigable...REGULATIONS Specific Requirements Maryland § 117.543 Bear Creek. (a) The draws of the Baltimore County...

  7. Adaptive prognostics for rolling element bearing condition

    Microsoft Academic Search

    Y. Li; S. Billington; C. Zhang; T. Kurfess; S. Danyluk; S. Liang

    1999-01-01

    Rolling element bearing failure is one of the foremost causes of breakdown in rotating machinery. This paper proposes a remaining life adaptation methodology based on mechanistic modeling and parameter tuning. Vibration measurement is used to estimate defect severity by monitoring the signals generated from rotating bearings. Through a defect propagation model and defect diagnostic model, an adaptive algorithm is developed

  8. Distributed bearing estimation via matrix completion

    Microsoft Academic Search

    Andrew Waters; Volkan Cevher

    2010-01-01

    We consider bearing estimation of multiple narrow-band plane waves impinging on an array of sensors. For this problem, bearing estimation algorithms such as minimum variance distortionless response (MVDR), multiple signal classification, and maximum likelihood generally require the array covariance matrix as sufficient statistics. Interestingly, the rank of the array covariance matrix is approximately equal to the number of the sources,

  9. Control Method of Heavy Hydrostatic Thrust Bearing

    Microsoft Academic Search

    Guihua Han; Jianying Li; Yuhong Dong; Junpeng Shao

    2009-01-01

    A hybrid fuzzy control scheme was applied to improve the rigidity of hydrostatic thrust bearing. The bearing oil film control was realized by coupling oil film thickness of four controllable chambers. The chamber flow can be regulated by electro hydraulic servo valve-control variable pump according to the surface roughness, load, cutting force, and thermal effects of worktable. The nonlinear hybrid

  10. Long-wearing TFE/metal bearings

    NASA Technical Reports Server (NTRS)

    Brass, R. A.; Gillon, W. A., Jr.

    1980-01-01

    Method for making metal/polytetrafluoroethylene (TFE) bearing surfaces embeds long-wearing layer of TFE in microscopic pits in metal. Technique has potential applications in automotive gears, ball joints, and roller chain components. Other applications are in use of unlubricated bearings in chemical, pharmaceutical, and food-processing equipment.

  11. Inbreeding depression in brown bear Ursus arctos

    Microsoft Academic Search

    Linda Laikre; Robert Andrén; Hans-Ove Larsson; Nils Ryman

    1996-01-01

    This note reports the occurrence of inbreeding depression in a captive brown bear Ursus arctos population. We analyzed studbook records of brown bears bred in Nordic zoos and found a significant reduction in litter size following an increase of inbreeding. In addition, albinism is associated with inbreeding in this population. The amount of depression is compared to that found in

  12. Evaluation of the wear of the pivot bearing in the Gyro C1E3 pump.

    PubMed

    Makinouchi, K; Nakazawa, T; Takami, Y; Takatani, S; Nosé, Y

    1996-06-01

    To estimate the lifetime of the pivot bearing system of the sealless centrifugal Gyro C1E3 pump, pivot bearing wear phenomena of the C1E3 were studied. The pivot bearing system consisted of a male and female pivot made of ceramics and ultrahigh molecular weight polyethylene (UHMWPE), respectively. First, many pumping tests were performed with the C1E3 under various pumping conditions, and the effects of impeller position and fluid on wear were analyzed. Through these preliminary tests, it was found that the wear progress of the pivot bearing consisted of initial wear and stationary wear. Most of this initial wear is caused by the plastic deformation of the polyethylene female pivot. It also was observed that bovine blood was almost comparable to water in its effect on the stationary wear rate at the same rotational speed. Based on these results, a long-term pumping test was performed with the C1E3, and initial and stationary wear rates were determined. At the same time, the maximal loosening distance (LDmax) (permissible total wear) of the C1E3 was determined experimentally from hemolytic and hydraulic performance perspectives. By using experimentally determined parameters the lifetime of the pivot bearing system of the C1E3 was typically 10 years for right ventricular assist, 8 years for left ventricular assist, and 5 years for cardiopulmonary bypass. PMID:8817949

  13. New entries in Lewis acid-Lewis base bifunctional asymmetric catalyst: catalytic enantioselective Reissert reaction of pyridine derivatives.

    PubMed

    Ichikawa, Eiko; Suzuki, Masato; Yabu, Kazuo; Albert, Matthias; Kanai, Motomu; Shibasaki, Masakatsu

    2004-09-29

    The first catalytic enantioselective Reissert reaction of pyridine derivatives that affords products with excellent regio- and enantioselectivity is described. The key for success is the development of new Lewis acid-Lewis base bifunctional asymmetric catalysts containing an aluminum as a Lewis acid and sulfoxides or phosphine sulfides as a Lewis base. These reactions are useful for the synthesis of a variety of chiral piperidine subunits, and catalytic enantioselective formal synthesis of CP-293,019, a selective D4 receptor antagonist, was achieved. Preliminary mechanistic studies indicated that both sulfoxides and phosphine sulfides can activate TMSCN as a Lewis base. In addition, the sulfoxides with appropriate stereochemistry might stabilize a highly enantioselective bimetallic complex (a presumed active catalyst) through internal coordination to aluminum. PMID:15382912

  14. A bi-functional device for self-powered electrochromic window and self-rechargeable transparent battery applications

    NASA Astrophysics Data System (ADS)

    Wang, Jinmin; Zhang, Lei; Yu, Le; Jiao, Zhihui; Xie, Huaqing; Lou, Xiong Wen (David); Wei Sun, Xiao

    2014-09-01

    Electrochromic smart windows are regarded as a good choice for green buildings. However, conventional devices need external biases to operate, which causes additional energy consumption. Here we report a self-powered electrochromic window, which can be used as a self-rechargeable battery. We use aluminium to reduce Prussian blue (PB, blue in colour) to Prussian white (PW, colourless) in potassium chloride electrolyte, realizing a device capable of self-bleaching. Interestingly, the device can be self-recovered (gaining blue appearance again) by simply disconnecting the aluminium and PB electrodes, which is due to the spontaneous oxidation of PW to PB by the dissolved oxygen in aqueous solution. The self-operated bleaching and colouration suggest another important function of the device: a self-rechargeable transparent battery. Thus the PB/aluminium device we report here is bifunctional, that is, it is a self-powered electrochromic window as well as a self-rechargeable transparent battery.

  15. A bi-functional device for self-powered electrochromic window and self-rechargeable transparent battery applications.

    PubMed

    Wang, Jinmin; Zhang, Lei; Yu, Le; Jiao, Zhihui; Xie, Huaqing; Lou, Xiong Wen David; Sun, Xiao Wei

    2014-01-01

    Electrochromic smart windows are regarded as a good choice for green buildings. However, conventional devices need external biases to operate, which causes additional energy consumption. Here we report a self-powered electrochromic window, which can be used as a self-rechargeable battery. We use aluminium to reduce Prussian blue (PB, blue in colour) to Prussian white (PW, colourless) in potassium chloride electrolyte, realizing a device capable of self-bleaching. Interestingly, the device can be self-recovered (gaining blue appearance again) by simply disconnecting the aluminium and PB electrodes, which is due to the spontaneous oxidation of PW to PB by the dissolved oxygen in aqueous solution. The self-operated bleaching and colouration suggest another important function of the device: a self-rechargeable transparent battery. Thus the PB/aluminium device we report here is bifunctional, that is, it is a self-powered electrochromic window as well as a self-rechargeable transparent battery. PMID:25247385

  16. NAD-Dependent DNA-Binding Activity of the Bifunctional NadR Regulator of Salmonella typhimurium

    PubMed Central

    Penfound, Thomas; Foster, John W.

    1999-01-01

    NadR is a 45-kDa bifunctional regulator protein. In vivo genetic studies indicate that NadR represses three genes involved in the biosynthesis of NAD. It also participates with an integral membrane protein (PnuC) in the import of nicotinamide mononucleotide, an NAD precursor. NadR was overexpressed and purified as a His-tagged fusion in order to study its DNA-binding properties. The protein bound to DNA fragments containing NAD box consensus sequences. NAD proved to be the relevant in vivo corepressor, but full NAD dependence of repressor activity required nucleotide triphosphates. DNA footprint analysis and gel shift assays suggest that NadR binds as a multimer to adjacent NAD boxes. The DNA-repressor complex would sequester a potential RNA polymerase binding site and thereby decrease expression of the nad regulon. PMID:9882682

  17. The EpsE Flagellar Clutch Is Bifunctional and Synergizes with EPS Biosynthesis to Promote Bacillus subtilis Biofilm Formation

    PubMed Central

    Guttenplan, Sarah B.; Blair, Kris M.; Kearns, Daniel B.

    2010-01-01

    Many bacteria inhibit motility concomitant with the synthesis of an extracellular polysaccharide matrix and the formation of biofilm aggregates. In Bacillus subtilis biofilms, motility is inhibited by EpsE, which acts as a clutch on the flagella rotor to inhibit motility, and which is encoded within the 15 gene eps operon required for EPS production. EpsE shows sequence similarity to the glycosyltransferase family of enzymes, and we demonstrate that the conserved active site motif is required for EPS biosynthesis. We also screen for residues specifically required for either clutch or enzymatic activity and demonstrate that the two functions are genetically separable. Finally, we show that, whereas EPS synthesis activity is dominant for biofilm formation, both functions of EpsE synergize to stabilize cell aggregates and relieve selective pressure to abolish motility by genetic mutation. Thus, the transition from motility to biofilm formation may be governed by a single bifunctional enzyme. PMID:21170308

  18. Synthesis of a bifunctional cytidine derivative and its conjugation to RNA for in vitro selection of a cytidine deaminase ribozyme

    PubMed Central

    Rublack, Nico

    2014-01-01

    Summary Over the past 20 years, the generation of functional RNAs by in vitro selection has become a standard technique. Apart from aptamers for simple binding of defined ligands, also RNAs for catalysis of chemical reactions have been selected. In the latter case, a key step often is the conjugation of one of the two reactants to the library, requiring suitable strategies for terminal or internal RNA functionalization. With the aim of selecting a ribozyme for deamination of cytidine, we have set up a selection scheme involving the attachment of the cytidine acting as deamination substrate to the 3'-terminus of the RNAs in the library, and library immobilization. Here, we report the synthesis of a bifunctional cytidine derivative suitable for conjugation to RNA and linkage of the conjugated library to a streptavidine-coated surface. Successful conjugation of the cytidine derivative to the 3'-terminus of a model RNA is demonstrated. PMID:25246949

  19. Effect of the hydrogenating component of bifunctional zeolitecontaining catalysts on the composition of the hydrogenation products of carbon monoxide

    SciTech Connect

    Ivanova, A.S.; Egorova, L.S.; Ione, K.G.; Poshis, A.V.

    1985-09-01

    This paper presents a study on the Fe/M ratio, where M is a group V-VIII metal in bifunctional zeolite-containing catalysts on the composition of the hydrocarbon products of the hydrogenation of carbon monoxide under different reaction conditions. Additives introduced into the iron-containing component may be divided into two groups: group I) Mn, V. and Mn-V facilitate an enhancement of the products in the epsilonC/sub 5/+ fraction and group II) Sb, ce, cu, Mo and Mn-Mo which gave an enhancement in the volatile hydrocarbon fraction epsilonC/sub 2/-C/sub 4/. The nature of the zeolite (high-silicon or erionite) affects the selectivity of the transformation of CO and H/sub 2/.

  20. A Ni-Fe-Cu center in a bifunctional carbon monoxide dehydrogenase/acetyl-CoA synthase.

    PubMed

    Doukov, Tzanko I; Iverson, Tina M; Seravalli, Javier; Ragsdale, Stephen W; Drennan, Catherine L

    2002-10-18

    A metallocofactor containing iron, sulfur, copper, and nickel has been discovered in the enzyme carbon monoxide dehydrogenase/acetyl-CoA (coenzyme A) synthase from Moorella thermoacetica (f. Clostridium thermoaceticum). Our structure at 2.2 angstrom resolution reveals that the cofactor responsible for the assembly of acetyl-CoA contains a [Fe4S4] cubane bridged to a copper-nickel binuclear site. The presence of these three metals together in one cluster was unanticipated and suggests a newly discovered role for copper in biology. The different active sites of this bifunctional enzyme complex are connected via a channel, 138 angstroms long, that provides a conduit for carbon monoxide generated at the C-cluster on one subunit to be incorporated into acetyl-CoA at the A-cluster on the other subunit. PMID:12386327

  1. The EpsE flagellar clutch is bifunctional and synergizes with EPS biosynthesis to promote Bacillus subtilis biofilm formation.

    PubMed

    Guttenplan, Sarah B; Blair, Kris M; Kearns, Daniel B

    2010-01-01

    Many bacteria inhibit motility concomitant with the synthesis of an extracellular polysaccharide matrix and the formation of biofilm aggregates. In Bacillus subtilis biofilms, motility is inhibited by EpsE, which acts as a clutch on the flagella rotor to inhibit motility, and which is encoded within the 15 gene eps operon required for EPS production. EpsE shows sequence similarity to the glycosyltransferase family of enzymes, and we demonstrate that the conserved active site motif is required for EPS biosynthesis. We also screen for residues specifically required for either clutch or enzymatic activity and demonstrate that the two functions are genetically separable. Finally, we show that, whereas EPS synthesis activity is dominant for biofilm formation, both functions of EpsE synergize to stabilize cell aggregates and relieve selective pressure to abolish motility by genetic mutation. Thus, the transition from motility to biofilm formation may be governed by a single bifunctional enzyme. PMID:21170308

  2. Effects of support on bifunctional methanol oxidation pathways catalyzed by polyoxometallate keggin clusters

    SciTech Connect

    Liu, Haichao; Iglesia, Enrique

    2003-12-26

    H5PV2Mo10O40 polyoxometallate Keggin clusters supported on ZrO2, TiO2, SiO2, and Al2O3 are effective catalysts for CH3OH oxidation reactions to form HCHO, methyl formate (MF), and dimethoxymethane (DMM). Rates and selectivities and the structure of supported clusters depend on the surface properties of the oxide supports. Raman spectroscopy showed that Keggin structures remained essentially intact on ZrO2, TiO2, and SiO2 after treatment in air at 553 K, but decomposed to MoOx and VOx oligomers on Al2O3. Accessible protons per Keggin unit (KU) were measured during CH3OH oxidation by titration with 2,6-di-tert-butyl pyridine. For similar KU surface densities (0.28 0.37 KU/nm2), the number of accessible protons was larger on SiO2 than on ZrO2 and TiO2 and much smaller on Al2O3 supports, even though residual dimethyl ether (DME) synthesis rates after titrant saturation indicated that the fractional dispersion of KU was similar on the first three supports. These effects of support on structure and on H+ accessibility reflect varying extents of interaction between polyoxometallate clusters and supports. Rates of CH3OH oxidative dehydrogenation per KU were higher on ZrO2 and TiO2 than on SiO2 at similar KU surface densities (0.28 0.37 KU/nm2) and dispersion, indicating that redox properties of Keggin clusters depend on the identity of the support used to disperse them. ZrO2 and TiO2 supports appear to enhance the reducibility of anchored polyoxometallate clusters. Rates were much lower on Al2O3, because structural degradation led to less reactive MoOx and VOx domains. CH3OH reactions involve primary oxidation to form HCHO and subsequent secondary reactions to form DMM and MF. These reactions involve HCHO CH3OH acetalization steps leading to methoxymethanol (CH3OCH2OH) or hemiacetal intermediates, which condense with CH3OH on acid sites to form DMM or dehydrogenate to form MF. COx formation rates are much lower than those of other reactions, and DME forms in parallel pathways catalyzed by acid sites. Secondary reactions leading to DMM and MF are strongly influenced by the chemical properties of support surfaces. Acidic SiO2 surfaces favored DMM formation, while amphoteric or dehydrogenating surfaces on ZrO2 and TiO2 led to MF formation, as a result of the varying role of each support in directing the reactions of HCHO and CH3OH and of the CH3OCH2OH intermediates toward DMM or MF, which was confirmed using physical catalyst pure support mixtures. These support effects reflect the bifunctional pathways of CH3OH reactions. These pathways are consistent with the effects of residence time and of the partial removal of H+ sites by titration using 2,6-di-tert-butyl pyridine.

  3. Rotor and bearing system for a turbomachine

    DOEpatents

    Lubell, Daniel; Weissert, Dennis

    2006-09-26

    A rotor and bearing system for a turbomachine. The turbomachine includes a drive shaft, an impeller positioned on the drive shaft, and a turbine positioned on the drive shaft proximate to the impeller. The bearing system comprises one gas journal bearing supporting the drive shaft between the impeller and the turbine. The area between the impeller and the turbine is an area of increased heat along the drive shaft in comparison to other locations along the drive shaft. The section of the drive shaft positioned between impeller and the turbine is also a section of the drive shaft that experiences increased stressed and load in the turbomachine. The inventive bearing machine system positions only one radial bearing in this area of increased stress and load.

  4. Ball bearing tests to evaluate Duroid replacements

    NASA Astrophysics Data System (ADS)

    Anderson, M. J.

    2001-09-01

    ESTL has completed a programme to identify and qualify a self-lubricating material to replace RT/duroid 5813 ("Duroid"), for ball bearing cage applications in space mechanisms. Following literature reviews, material evaluations, friction and wear testing and a ball bearing screening test programme, PGM-HT (a PTFE/MoS2/glass fibre composite) was selected for evaluation in ball bearings. PGM-HT cages were tested extensively in conditions representative of that experienced by a selection of current mechanism applications. Different types (and sizes) of ball bearings and cages were tested over a range of operating speeds, loads (contact stresses) and under different environments. From these tests, it was concluded that the torque behaviour of PGM-HT lubricated bearings was identical to that of Duroid. A design guide was then prepared to summarise the findings and assist designers with torque and lifetime predictions.

  5. Flywheel energy storage with superconductor magnetic bearings

    SciTech Connect

    Weinberger, B.R.; Lynds, L. Jr.

    1993-06-01

    A system for storing energy in a flywheel suspended by magnetic levitation in a vacuum vessel is described comprising: a rotatable member having a rotation axis in a central shaft said shaft having first and second magnetic tips formed from permanent magnets on opposite ends thereof, superconductor magnetic bearings, positioned to support said first and second magnetic tips and supported in turn by bearing support means, said superconductor magnetic bearings having a main direction of lift; cooling means in thermal contact with said bearing support means; and energy transfer means, connected to said rotatable member, for transferring energy into and extracting energy from said rotatable member, characterized in that: at least one of said superconducting bearings includes a lifting portion comprising melt-processed, directionally solidified material structure having a crystal structure C-axis oriented parallel to said main direction of lift.

  6. Hydrodynamic air lubricated compliant surface bearing for an automotive gas turbine engine. 1: Journal bearing performance

    NASA Technical Reports Server (NTRS)

    Ruscitto, D.; Mccormick, J.; Gray, S.

    1978-01-01

    A 38.1 mm (1.5 inch) diameter Hydresil Compliant Surface Air Lubricated Journal Bearing was designed and tested to obtain bearing performance characteristics at both room temperature and 315 C (600 F). Testing was performed at various speeds up to 60,000 rpm with varying loads. Rotating sensors provided an opportunity to examine the film characteristics of the compliant surface bearing. In addition to providing minimum film thickness values and profiles, many other insights into bearing operation were gained such as the influence of bearing fabrication accuracy and the influence of smooth foil deflection between the bumps.

  7. Behavioural differences between single scandinavian brown bears (Ursus arctos) and females with dependent young when experimentally approached by humans.

    PubMed

    Sahlén, Veronica; Ordiz, Andrés; Swenson, Jon E; Støen, Ole Gunnar

    2015-01-01

    Carnivore-human encounters that result in human injury present a conservation and management challenge and it is therefore important to understand under what conditions such incidents occur. Females with cubs are often involved when humans are injured by brown bears Ursus arctos. In Scandinavia, this is particularly true for unarmed recreational forest users. Our aim was to document behavioural differences between single bears and females with cubs in order to develop recommendations to minimize the risk of injuries to recreational forest users. We documented the reactions of GPS-collared females with cubs and single brown bears to experimental approaches by humans to 50 m from the bear on 42 and 108 occasions, respectively. The majority of females with cubs (95%) and single bears (89%) left when approached. Bears that left were passed at shorter distances and were in more open areas than those that stayed. Both groups had similar flight initiation distances, which were longer for bears that were active at the time of the disturbance. Females with cubs selected more open habitat than single bears, also for the new site they selected following disturbance. Females with cubs, particularly active females with cubs of the year, moved greater distances and spent more time active following the approach. Females with cubs and single bears were seen or heard in 26% and 14% of the approaches, respectively. None of the bears displayed any aggressive behaviour during the approaches. Females with cubs selected more open habitat, perhaps predisposing them to encountering people that are not involved in hunting activities, which might be the primary explanation why females with cubs are most frequently involved when unarmed people are injured by bears in Scandinavia. To mitigate injury risks, one must consider factors that bring bears closer to human activity in the first place. PMID:25830333

  8. Xenon in And at the End of the Tunnel of Bifunctional Carbon Monoxide Dehydrogenase/Acetyl-CoA Synthase

    SciTech Connect

    Doukov, T.I.; Blasiak, L.C.; Seravalli, J.; Ragsdale, S.W.; Drennan, C.L.; /MIT /SLAC, SSRL /Nebraska U.

    2009-05-11

    A fascinating feature of some bifunctional enzymes is the presence of an internal channel or tunnel to connect the multiple active sites. A channel can allow for a reaction intermediate generated at one active site to be used as a substrate at a second active site, without the need for the intermediate to leave the safety of the protein matrix. One such bifunctional enzyme is carbon monoxide dehydrogenase/acetyl-CoA synthase from Moorella thermoacetica (mtCODH/ACS). A key player in the global carbon cycle, CODH/ACS uses a Ni-Fe-S center called the C-cluster to reduce carbon dioxide to carbon monoxide and uses a second Ni-Fe-S center, called the A-cluster, to assemble acetyl-CoA from a methyl group, coenzyme A, and C-cluster-generated CO. mtCODH/ACS has been proposed to contain one of the longest enzyme channels (138 A long) to allow for intermolecular CO transport. Here, we report a 2.5 A resolution structure of xenon-pressurized mtCODH/ACS and examine the nature of gaseous cavities within this enzyme. We find that the cavity calculation program CAVENV accurately predicts the channels connecting the C- and A-clusters, with 17 of 19 xenon binding sites within the predicted regions. Using this X-ray data, we analyze the amino acid composition surrounding the 19 Xe sites and consider how the protein fold is utilized to carve out such an impressive interior passageway. Finally, structural comparisons of Xe-pressurized mtCODH/ACS with related enzyme structures allow us to study channel design principles, as well as consider the conformational flexibility of an enzyme that contains a cavity through its center.

  9. Structure of the phosphotransferase domain of the bifunctional aminoglycoside-resistance enzyme AAC(6?)-Ie-APH(2??)-Ia

    PubMed Central

    Smith, Clyde A.; Toth, Marta; Bhattacharya, Monolekha; Frase, Hilary; Vakulenko, Sergei B.

    2014-01-01

    The bifunctional acetyltransferase(6?)-Ie-phosphotransfer­ase(2??)-Ia [AAC(6?)-Ie-APH(2??)-Ia] is the most important aminoglycoside-resistance enzyme in Gram-positive bacteria, conferring resistance to almost all known aminoglycoside antibiotics in clinical use. Owing to its importance, this enzyme has been the focus of intensive research since its isolation in the mid-1980s but, despite much effort, structural details of AAC(6?)-Ie-APH(2??)-Ia have remained elusive. The structure of the Mg2GDP complex of the APH(2??)-Ia domain of the bifunctional enzyme has now been determined at 2.3?Å resolution. The structure of APH(2??)-Ia is reminiscent of the structures of other aminoglycoside phosphotransferases, having a two-domain architecture with the nucleotide-binding site located at the junction of the two domains. Unlike the previously characterized APH(2??)-IIa and APH(2??)-IVa enzymes, which are capable of utilizing both ATP and GTP as the phosphate donors, APH(2??)-Ia uses GTP exclusively in the phosphorylation of the aminoglycoside antibiotics, and in this regard closely resembles the GTP-dependent APH(2??)-IIIa enzyme. In APH(2??)-Ia this GTP selectivity is governed by the presence of a ‘gatekeeper’ residue, Tyr100, the side chain of which projects into the active site and effectively blocks access to the adenine-binding template. Mutation of this tyrosine residue to a less bulky phenylalanine provides better access for ATP to the NTP-binding template and converts APH(2??)-Ia into a dual-specificity enzyme. PMID:24914967

  10. Xenon in and at the end of the tunnel of bifunctional carbon monoxide dehydrogenase/acetyl-CoA synthase.

    PubMed

    Doukov, Tzanko I; Blasiak, Leah C; Seravalli, Javier; Ragsdale, Stephen W; Drennan, Catherine L

    2008-03-18

    A fascinating feature of some bifunctional enzymes is the presence of an internal channel or tunnel to connect the multiple active sites. A channel can allow for a reaction intermediate generated at one active site to be used as a substrate at a second active site, without the need for the intermediate to leave the safety of the protein matrix. One such bifunctional enzyme is carbon monoxide dehydrogenase/acetyl-CoA synthase from Moorella thermoacetica (mtCODH/ACS). A key player in the global carbon cycle, CODH/ACS uses a Ni-Fe-S center called the C-cluster to reduce carbon dioxide to carbon monoxide and uses a second Ni-Fe-S center, called the A-cluster, to assemble acetyl-CoA from a methyl group, coenzyme A, and C-cluster-generated CO. mtCODH/ACS has been proposed to contain one of the longest enzyme channels (138 A long) to allow for intermolecular CO transport. Here, we report a 2.5 A resolution structure of xenon-pressurized mtCODH/ACS and examine the nature of gaseous cavities within this enzyme. We find that the cavity calculation program CAVENV accurately predicts the channels connecting the C- and A-clusters, with 17 of 19 xenon binding sites within the predicted regions. Using this X-ray data, we analyze the amino acid composition surrounding the 19 Xe sites and consider how the protein fold is utilized to carve out such an impressive interior passageway. Finally, structural comparisons of Xe-pressurized mtCODH/ACS with related enzyme structures allow us to study channel design principles, as well as consider the conformational flexibility of an enzyme that contains a cavity through its center. PMID:18293927

  11. Optico-cochleo-dentate degeneration associated with severe peripheral neuropathy and caused by peroxisomal D-bifunctional protein deficiency.

    PubMed

    Schröder, J M; Hackel, V; Wanders, R J A; Göhlich-Ratmann, G; Voit, T

    2004-08-01

    The clinical, neuroradiological, neuropathological and biochemical findings in a patient with optico-cochleo-dentate degeneration (OCDD; OMIM 258700) are presented in a severe case succumbing at the age of 4 years. The electron microscopic and biochemical data showed for the first time that OCDD may occur as the phenotypic expression of D-bifunctional protein deficiency, i.e., a peroxisomal disorder. The boy was born as the first child of healthy, consanguineous parents of Turkish origin. No other family members were affected. The main clinical symptoms consisted of muscle hypotonia ("floppy infant"), generalized epileptic fits, hypacusis, rotatory nystagmus, insufficient pupillary reactions, and mental retardation. Fibroblast cultures revealed D-bifunctional protein deficiency. Neuropathological examination displayed moderate frontoparietal and insular microgyria, and atrophy of the cerebellum. Loss of neurons was severe in the granular layer, the Purkinje cell band of the cerebellum, and rather complete in the dentate nucleus. A corresponding loss of myelinated fibers associated with characteristic periodic acid-Schiff-positive macrophages was most prominent in the white matter of the cerebellum. There was additional severe loss of myelinated fibers in the central portions of the optic nerve, reduction of the nerve fiber density in the cochlear nerve, and reduction of myelinated nerve fibers by about 80-90% in the sural nerve, which has not been studied in previous cases. At the electron microscopic level, characteristic inclusions mainly in perivascular macrophages and astrocytes were the most prominent finding. The inclusions usually showed a bilaminar structure, whereas trilaminar structures, typically seen in adrenoleukodystrophy, and multilaminar structures were less frequently seen. PMID:15235808

  12. Clinical Outcomes Assessment of Three Similar Hip Arthroplasty Bearing Surfaces

    PubMed Central

    Parsons, Christopher; Batson, Ryan; Reighard, Shane; Tanner, Stephanie; Snider, Becky; Pace, Thomas B.

    2014-01-01

    This report examines the clinical performance of three very similar total hip arthroplasty designs with distinctly different bearing surfaces used over the course 10-17 years. Clinical outcomes assessments for each group are compared in the context of varying implant related costs related to the latest technology at the time of surgery. Eighty-one surgeries were studied and differ by bearing surface. In this study, 36 hips are ceramic on polyethylene, 27 are metal on polyethylene and 18 are metal on metal. All polyethylene components are nonhighly cross-linked. The ceramic on polyethylene group has younger patients, on average, and higher percentage of patients with significant polyethylene wear. These groups have an average follow-up time of 8.6 years when assessing functional hip scores, thigh pain, groin pain, revision surgeries and radiographic osteolysis. The implant purchasing cost at the time of surgery was assessed to determine if a correlation exists between outcomes and the more technologically advanced implants use at the time of surgery. Based on midterm clinical outcome assessment, no correlation between initial hospital cost and clinical outcomes of one bearing surface over another can be found. PMID:25002938

  13. Modeling of Rolling Element Bearing Mechanics: Computer Program Updates

    NASA Technical Reports Server (NTRS)

    Ryan, S. G.

    1997-01-01

    The Rolling Element Bearing Analysis System (REBANS) extends the capability available with traditional quasi-static bearing analysis programs by including the effects of bearing race and support flexibility. This tool was developed under contract for NASA-MSFC. The initial version delivered at the close of the contract contained several errors and exhibited numerous convergence difficulties. The program has been modified in-house at MSFC to correct the errors and greatly improve the convergence. The modifications consist of significant changes in the problem formulation and nonlinear convergence procedures. The original approach utilized sequential convergence for nested loops to achieve final convergence. This approach proved to be seriously deficient in robustness. Convergence was more the exception than the rule. The approach was changed to iterate all variables simultaneously. This approach has the advantage of using knowledge of the effect of each variable on each other variable (via the system Jacobian) when determining the incremental changes. This method has proved to be quite robust in its convergence. This technical memorandum documents the changes required for the original Theoretical Manual and User's Manual due to the new approach.

  14. Bearing tester data compilation, analysis, and reporting and bearing math modeling

    NASA Technical Reports Server (NTRS)

    1983-01-01

    The Shaberth bearing analysis computer program was developed for the analysis of jet engine shaft/bearing systems operating above room temperature with normal hydrocarbon lubricants. It is also possible to use this tool to evaluate the shaft bearing systems operating in cryogenics. Effects such as fluid drag, radial temperature gradients, outer race misalignments and clearance changes were simulated and evaluated. In addition, the speed and preload effects on bearing radial stiffness was evaluated. The Shaberth program was also used to provide contact stresses from which contact geometry was calculated to support other analyses such as the determination of cryogenic fluid film thickness in the contacts and evaluation of surface and subsurface stresses necessary for bearing failure evaluation. This program was a vital tool for the thermal analysis of the bearing in that it provides the heat generation rates at the rolling element/race contacts for input into a thermal model of the bearing/shaft assembly.

  15. Initials Autobiography

    NSDL National Science Digital Library

    Format Edit

    2012-04-30

    Using excerpts from Roald Dahl's Boy: Tales of Childhood and D is for Dahl: A gloriumptious A-Z guide to the World of Roald Dahl compiled by Wendy Cooling the students will compare and contrast biographies and autobiographies. They will identify and chart the differences between each. As a culminating assignment, students will compose their own autobiography using only their initials.

  16. Assessment of bearing pad fretting flaws in CANDU Zr-Nb pressure tubes

    SciTech Connect

    Scarth, D.A.; Mok, D.H.B. [Ontario Hydro Technologies, Toronto, Ontario (Canada); Newman, G.W. [Ontario Hydro Nuclear, Toronto, Ontario (Canada)

    1996-12-01

    Flaws due to fretting of the fuel bundle bearing pads on the inside wall of the pressure tubes have been detected in some Ontario Hydro CANDU reactors. The major pressure tube structural integrity consideration with these flaws is delayed hydride cracking initiation. CANDU-specific fitness-for-service evaluation procedures have been developed to evaluate these flaws for pressure tube structural integrity. These procedures are described in this paper, along with an example assessment of actual inservice flaws. Experience to date with bearing pad fretting flaws has been favorable. Crack growth from a flaw has not been detected. Thus far, all bearing pad fretting flaws which have been evaluated have satisfied the acceptance criteria. The example assessment demonstrates that the most limiting factor in terms of reactor operation is the reactor Heatup/Cooldown cycles limit from the delayed hydride cracking initiation evaluation. However, the Heatup/Cooldown cycles limit has not necessitated removal of a pressure tube.

  17. 19 CFR 133.21 - Articles bearing counterfeit trademarks.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ...2012-04-01 2012-04-01 false Articles bearing counterfeit trademarks. 133.21 ...NAMES, AND COPYRIGHTS Importations Bearing Registered and/or Recorded Trademarks...Recorded Trade Names § 133.21 Articles bearing counterfeit trademarks. (a)...

  18. 46 CFR 61.20-23 - Tailshaft clearance; bearing weardown.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ...2012-10-01 false Tailshaft clearance; bearing weardown. 61.20-23 Section 61.20-23...Equipment § 61.20-23 Tailshaft clearance; bearing weardown. (a) Water lubricated bearings, other than rubber, must be rebushed as...

  19. 46 CFR 61.20-23 - Tailshaft clearance; bearing weardown.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ...2013-10-01 false Tailshaft clearance; bearing weardown. 61.20-23 Section 61.20-23...Equipment § 61.20-23 Tailshaft clearance; bearing weardown. (a) Water lubricated bearings, other than rubber, must be rebushed as...

  20. 12 CFR 330.16 - Noninterest-bearing transaction accounts.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ...2012-01-01 false Noninterest-bearing transaction accounts. 330.16 Section...COVERAGE § 330.16 Noninterest-bearing transaction accounts. (a) Separate...depositor's funds in a “noninterest-bearing transaction account” (as...