Science.gov

Sample records for bifunctional initiator bearing

  1. Radical initiated polymerization in a bifunctional mixture via computer simulation

    NASA Astrophysics Data System (ADS)

    Diamond, Keri L.; Pandey, Ras B.; Thames, Shelby F.

    2004-06-01

    Computer simulations are performed to study the polymerization behavior in a mixture of bifunctional groups such as olefins (A) and acrylates (B) in an effective solvent (a coarse description for vegetable oil derived macromonomers (VOMMs) in solution) on a cubic lattice. A set of interactions between these units and solvent (S) constituents and their relative concentrations (pA, pB, and pS) are considered. Samples are equilibrated with Metropolis algorithm to model the perceived behavior of VOMMs. The covalent bonding between monomeric units is then implemented via reaction pathways initiated by stochastic motion of free radicals (a very small fraction). The rate of reaction shows decay patterns with the time steps (t) with power laws (i.e., Rabαt-r, r≅0.4-0.8), exponential decays (i.e., Rabαe-0.001t), and their combination. Growth of A-B bonding is studied as a function of polymer concentration p=pA+pB for four different model systems appropriate for VOMMs. The data from the free radical initiated simulations are compared to the original simulations with homopolymerization. While most of the data are consistent with experimental observations, the variations are found to be model dependent.

  2. Concurrent Initialization for Bearing-Only SLAM

    PubMed Central

    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

  3. 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

  4. Organocatalytic asymmetric Henry reaction of 1H-pyrrole-2,3-diones with bifunctional amine-thiourea catalysts bearing multiple hydrogen-bond donors.

    PubMed

    Zhang, Ming-Liang; Yue, Deng-Feng; Wang, Zhen-Hua; Luo, Yuan; Xu, Xiao-Ying; Zhang, Xiao-Mei; Yuan, Wei-Cheng

    2016-01-01

    For the first time, a catalytic asymmetric Henry reaction of 1H-pyrrole-2,3-diones was achieved with a chiral bifunctional amine-thiourea as a catalyst possessing multiple hydrogen-bond donors. With this developed method, a range of 3-hydroxy-3-nitromethyl-1H-pyrrol-2(3H)-ones bearing quaternary stereocenters were obtained in acceptable yield (up to 75%) and enantioselectivity (up to 73% ee). PMID:26977188

  5. Organocatalytic asymmetric Henry reaction of 1H-pyrrole-2,3-diones with bifunctional amine-thiourea catalysts bearing multiple hydrogen-bond donors

    PubMed Central

    Zhang, Ming-Liang; Yue, Deng-Feng; Wang, Zhen-Hua; Luo, Yuan; Zhang, Xiao-Mei

    2016-01-01

    Summary For the first time, a catalytic asymmetric Henry reaction of 1H-pyrrole-2,3-diones was achieved with a chiral bifunctional amine-thiourea as a catalyst possessing multiple hydrogen-bond donors. With this developed method, a range of 3-hydroxy-3-nitromethyl-1H-pyrrol-2(3H)-ones bearing quaternary stereocenters were obtained in acceptable yield (up to 75%) and enantioselectivity (up to 73% ee). PMID:26977188

  6. Controlling the Reactivity of Bifunctional Ligands: Carboxylate-Bridged Nonheme Diiron(II) Complexes Bearing Free Thiol Groups.

    PubMed

    Pal, Nabhendu; Majumdar, Amit

    2016-03-21

    Carboxylate-bridged nonheme diiron(II) complexes, bearing free functional groups in general, and free thiol groups in particular, were sought. While the addition of sodium γ-hydroxybutyrate into a mixture of Fe(BF4)2·6H2O, HN-Et-HPTB, and Et3N afforded the complex [Fe2(N-Et-HPTB)(μ-O2C-(CH2)3-OH)](BF4)2 (2) (where N-Et-HPTB is the anion of N,N,N',N'-tetrakis(2-(1-ethylbenzimidazolyl))-2-hydroxy-1,3-diaminopropane), a similar, straightforward process could not be used for the synthesis of diiron(II) complexes with free thiol groups. In order to circumvent this problem, a new class of thiolate bridged diiron(II) complexes, [Fe2(N-Et-HPTB)(μ-SR(1))](BF4)2 (R(1) = Me (1a), Et (1b), (t)Bu (1c), Ph (1d)) was synthesized. Selective proton exchange reactions of one representative compound, 1b, with reagents of the type HS-R(2)-COOH yielded the target compounds, [Fe2(N-Et-HPTB)(μ-O2C-R(2)-SH)](BF4)2 (R(2) = C6H4 (3a), CH2CH2 (3b), CH2(CH2)5CH2 (3c)). Redox properties of the complexes 3a-3c were studied in comparison with the complex, [Fe2(N-Et-HPTB)(μ-O2CMe)](BF4)2 (5). Reaction of (Cp2Fe)(BF4) with 1b yielded [Fe(II)2(N-Et-HPTB)(DMF)3](BF4)3·DMF (4) (when crystallized from DMF/diethyl ether), which might indicate the formation of a transient ethanethiolate bridged {Fe(II)Fe(III)} species, followed by a rapid internal redox reaction to generate diethyldisulfide and the solvent coordinated diiron(II) complex, 4. This possibility was supported by a comparative cyclic voltammetric study of 1a-1c and 4. Prospects of the complexes of the type 3a-3c as potential building blocks for the synthesis of nonheme diiron(II) complexes covalently attached with other redox active metals has been substantiated by the synthesis of the complexes, [Fe2(N-EtHPTB)(μ-O2C-R(2)-S)Cu(Me3TACN)](BF4)2 (R = p-C6H4 (7a), CH2CH2 (7b)). All the compounds were characterized by a combination of single-crystal X-ray structure determinations and/or elemental analysis. PMID:26959857

  7. Sequential bearings-only-tracking initiation with particle filtering method.

    PubMed

    Liu, Bin; 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

  8. 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

  9. 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

    ... FR 20900 (May 15, 1989). On June 30, 2010, we initiated an administrative review of the order on ball..., 75 FR 37759 (June 30, 2010). After analysis of the quantity and value of the sales of ball bearings... International Trade Administration Ball Bearings and Parts Thereof From Germany: Initiation of Antidumping...

  10. Ionic Polymer Microspheres Bearing a Co(III) -Salen Moiety as a Bifunctional Heterogeneous Catalyst for the Efficient Cycloaddition of CO2 and Epoxides.

    PubMed

    Leng, Yan; Lu, Dan; Zhang, Chenjun; Jiang, Pingping; Zhang, Weijie; Wang, Jun

    2016-06-01

    We report a unique strategy to obtain the bifunctional heterogeneous catalyst TBB-Bpy@Salen-Co (TBB=1,2,4,5-tetrakis(bromomethyl)benzene, Bpy=4,4'-bipyridine, Salen-Co=N,N'-bis({4-dimethylamino}salicylidene)ethylenediamino cobalt(III) acetate) by combining a cross-linked ionic polymer with a Co(III) -salen Schiff base. The catalyst showed extra high activity for CO2 fixation under mild, solvent-free reaction conditions with no requirement for a co-catalyst. The synthesized catalyst possessed distinctive spherical structural features, abundant halogen Br(-) anions with good leaving group ability, and accessible Lewis acidic Co metal centers. These unique features, together with the synergistic role of the Co and Br(-) functional sites, allowed TBB-Bpy@Salen-Co to exhibit enhanced catalytic conversion of CO2 into cyclic carbonates relative to the corresponding monofunctional analogues. This catalyst can be easily recovered and recycled five times without significant leaching of Co or loss of activity. Moreover, based on our experimental results and previous work, a synergistic cycloaddition reaction mechanism was proposed. PMID:27116117

  11. Track initiation of bearings-only tracking based on ant navigation concept

    NASA Astrophysics Data System (ADS)

    Zhu, Jihong; Xu, Benlian; Wang, Zhiquan

    2010-11-01

    A novel heuristic track initiation method is developed for the bearing-only multi-sensor-multi-target tracking system, in which each target is assumed to move with a straight line. The key idea of the proposed method is derived from the ant navigation concept in its foraging life, which differs from the traditional ant colony optimization algorithm, and it utilizes the concept of path integration and visual landmarks in ants' navigation toolkit to find the exact positions of each target. Numerous numerical simulations are conducted and the effectiveness of the proposed track initiation method is verified according to the probability of correct track initiation.

  12. Pharmacokinetics of an anti-carcinoembryonic antigen monoclonal antibody conjugated to a bifunctional transition metal carborane complex (venus flytrap cluster) in tumor-bearing mice.

    PubMed

    Beatty, B G; Paxton, R J; Hawthorne, M F; Williams, L E; Rickard-Dickson, K J; Do, T; Shively, J E; Beatty, J D

    1993-08-01

    An anticarcinoembryonic antigen (CEA) monoclonal antibody, T84.66, has been conjugated to a metallocarborane complex (Venus flytrap cluster, VFC) containing 57Co. This radioimmunoconjugate, 57Co-VFC-T84.66, retained > 90% immunoreactivity, was stable in serum (7 days) and demonstrated good localization in LS174T tumor xenografts. Pharmacokinetics of 57Co-VFC-T84.66 in tumor-bearing mice were compared to T84.66 Mab conjugated with either DTPA or its benzylisothiocyanate derivative (BzDTPA) labeled with 111In. Whole-body half-life for VFC-T84.66 was less (t1/2 = 62 hr) than that for either DTPA-T84.66 (t1/2 = 157 hr) or BzDTPA-T84.66 (t1/2 = 167 hr). Blood clearance was similar for all three radioimmunoconjugates (t1/2 = 22 hr). Hepatic uptake of the radiolabel was rapid and remained constant for 7 days for both DTPA radioimmunoconjugates (DTPA radioimmunoconjugate = 13.7 +/- 1.5 %ID/g; BzDTPA radioimmunoconjugate = 10.4 +/- 1.7%ID/g). For VFC, however, liver radioactivity decreased from 19.1 +/- 0.6%ID/g at 1 hr to 0.9 +/- 0.1 %ID/g 7 days postinjection, suggesting a possible role for VFC radioimmunoconjugate in the imaging and therapy of liver metastases. PMID:8326387

  13. 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

    ... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF ENERGY Federal Energy Regulatory Commission Black Bear SO, LLC; Supplemental Notice That Initial Market-Based Rate...-referenced proceeding of Black Bear SO, LLC's application for market-based rate authority, with...

  14. 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

    ... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF ENERGY Federal Energy Regulatory Commission Tall Bear Group, LLC; Supplemental Notice That Initial Market- Based Rate...-referenced proceeding, of Tall Bear Group, LLC's application for market-based rate authority, with...

  15. MTBE OXIDATION BY BIFUNCTIONAL ALUMINUN

    EPA Science Inventory

    Bifunctional aluminum, prepared by sulfating zero-valent aluminum with sulfuric acid, is an innovative extension of zero-valent metal (ZVM) technology for ground water remediation. Bifunctional aluminum has a dual functionality of simultaneously decomposing both reductively- an...

  16. MTBE OXIDATION BY BIFUNCTIONAL ALUMINUM

    EPA Science Inventory

    Bifunctional aluminum, prepared by sulfating zero-valent aluminum with sulfuric acid, has a dual functionality of simultaneously decomposing both reductively- and oxidatively-degradable contaminants. In this work, the use of bifunctional aluminum for the degradation of methyl te...

  17. Bifunctional alkaline oxygen electrodes

    NASA Technical Reports Server (NTRS)

    Swette, L.; Kackley, N.; Mccatty, S. A.

    1991-01-01

    The authors describe the identification and testing of electrocatalysts and supports for the positive electrode of moderate-temperature, single-unit, rechargeable alkaline fuel cells. Recent work on Na(x)Pt3O4, a potential bifunctional catalyst, is described, as well as the application of novel approaches to the development of more efficient bifunctional electrode structures. The three dual-character electrodes considered here showed similar superior performance; the Pt/RhO2 and Rh/RhO2 electrodes showed slightly better performance than the Pt/IrO2 electrode. It is concluded that Na(x)Pt3O4 continues to be a promising bifunctional oxygen electrode catalyst but requires further investigation and development.

  18. Tight bifunctional hierarchical catalyst.

    PubMed

    Højholt, Karen T; Vennestrøm, Peter N R; Tiruvalam, Ramchandra; Beato, Pablo

    2011-12-28

    A new concept to prepare tight bifunctional catalysts has been developed, by anchoring CoMo(6) clusters on hierarchical ZSM-5 zeolites for simultaneous use in HDS and hydrocracking catalysis. The prepared material displays a significant improved activity in HDS catalysis compared to the impregnated counterpart. PMID:22048337

  19. The initial bearing capacities of subchondral bone replacements considerably contributing to chondrogenesis.

    PubMed

    Petrtýl, Miroslav; Danešová, Jana; Lísal, Jaroslav; Senolt, Ladislav; Hulejová, Hana; Polanská, Markéta; Bastl, Zdeněk; Kruliš, Zdeněk; Cerný, Pavel

    2010-01-01

    The degeneration of articular cartilage results from osteoarthritis and many other forms of severe arthritis. Current treatments for cartilage repair are less than satisfactory, and rarely restore a full function or return the tissue to its natural state. The leading strategies in the treatment are aimed at the transplantation of cells and/or the use of various biological grafts, bioactive agents, or biologically compatible implant matrices. The insertion of a crushed autologous bone graft has been reported as a possible therapy. However, the regenerative quality of the tissue was less than 70% of healthy cartilage for fragments and controls. The implantation of cycloolefin-blend 3D-cylinders with hydrogel scaffolds on their proximal parts and with the applications of type I collagen films is one of several surgical therapies. The replacement and continuous biomechanical properties of the subchondral bone play an important role in the morphology and the quality of chondrogenesis. The initial biomechanical stability of COC-blend polymer replacements in the subchondral bone contributes to the formation of a new cartilage tissue. The initial bearing capacities of the implanted tissue/replacements and vertical positions of the replacements have a principal influence upon both the quality and the quantity of new articular cartilage. PMID:21243971

  20. 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

    ... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF ENERGY Federal Energy Regulatory Commission Black Bear Development Holdings, LLC; Supplemental Notice that Initial Market-Based Rate Filing Includes Request for Blanket Section 204 Authorization This is a supplemental notice in the above-referenced proceeding...

  1. 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

    ... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF ENERGY Federal Energy Regulatory Commission Silver Bear Power, LLC; Supplemental Notice That Initial Market- Based Rate Filing Includes Request for Blanket Section 204 Authorization This is a supplemental notice in the above-referenced proceeding, of Silver...

  2. 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

    ... Republic of Germany, 54 FR 20900 (May 15, 1989). The orders on cylindrical roller bearings and spherical... Parts Thereof, From Germany; Final Results of New Shipper Antidumping Duty Administrative Review, 61 FR... and Parts Thereof from Germany: Final Results of Antidumping Duty Changed-Circumstances Review, 73...

  3. Initial studies on sperm cryopreservation of a live-bearing fish, the green swordtail Xiphophorus helleri.

    PubMed

    Huang, Changjiang; Dong, Qiaoxiang; Walter, Ronald B; Tiersch, Terrence R

    2004-07-01

    Swordtails and platyfish of the genus Xiphophorus are valuable models for biomedical research and are also commercially raised as ornamental fish valued by aquarists. While research use and commercial interest increases yearly in these fish, cryopreservation of sperm is unexplored in this genus. Xiphophorus are live-bearing fishes characterized by small body sizes, limited sperm volumes, and internal fertilization, an atypical reproductive mode for fish. These attributes make research involving cryopreservation of Xiphophorus germplasm challenging. To explore methods for sperm cryopreservation, this study evaluated the effect of different loading volumes of sperm suspension in 0.25-ml French straws, different dilution ratios of sperm to extender, an osmolality range of extender without cryoprotectant and with dimethyl sulfoxide (DMSO) as cryoprotectant, and short-term storage at room temperature and 4 degrees C after thawing. No significant difference in sperm motility due to straw loading volume was observed after thawing. Sperm motility was observed to decrease with increasing dilution. The osmolality of Hanks' balanced salt solution (HBSS) without cryoprotectant in which the highest sperm motility (67%) was observed was 320 +/- 3 mOsm/kg, which was also the osmolality of X. helleri blood plasma. When cryopreserved with 10% DMSO, however, the highest motilities within 10 min after thawing were observed with HBSS in the range of 240-300 mOsm/kg. Sperm suspended in HBSS at 320 mOsm/kg with a dilution factor of 100 maintained motility for 24h at room temperature, but persisted for 10 days when stored at 4 degrees C. These results provided the first evidence that cryopreservation may be applied to conservation of genetic resources in live-bearing fishes. PMID:15159112

  4. Bifunctional DTPA-type ligand

    SciTech Connect

    Gansow, O.A.; Brechbiel, M.W.

    1990-03-26

    The subject matter of the invention relates to bifunctional cyclohexyl DTPA ligands and methods of using these compounds. Specifically, such ligands are useful for radiolabeling proteins with radioactive metals, and can consequently be utilized with respect to radioimmunoimaging and/or radioimmunotherapy.

  5. Highly Stereoselective Synthesis of Cyclopentanes bearing Four Stereocenters by a Rhodium Carbene–Initiated Domino Sequence

    PubMed Central

    Parr, Brendan T.; Davies, Huw M. L.

    2014-01-01

    Stereoselective synthesis of a cyclopentane nucleus by convergent annulations constitutes a significant challenge for synthetic chemists. Though a number of biologically relevant cyclopentane natural products are known, more often than not, the cyclopentane core is assembled in a stepwise fashion due to lack of efficient annulation strategies. Herein, we report the rhodium-catalyzed reactions of vinyldiazoacetates with (E)-1,3-disubstituted 2-butenols generate cyclopentanes, containing four new stereogenic centers with very high levels of stereoselectivity (99% ee, >97 : 3 dr). The reaction proceeds by a carbene–initiated domino sequence consisting of five distinct steps: rhodium–bound oxonium ylide formation, [2,3]-sigmatropic rearrangement, oxy-Cope rearrangement, enol–keto tautomerization, and finally an intramolecular carbonyl ene reaction. A systematic study is presented detailing how to control chirality transfer in each of the four stereo-defining steps of the cascade, consummating in the development of a highly stereoselective process. PMID:25082301

  6. Genetics Home Reference: D-bifunctional protein deficiency

    MedlinePlus

    ... Genetics Home Health Conditions D-bifunctional protein deficiency D-bifunctional protein deficiency Enable Javascript to view the ... boxes. Download PDF Open All Close All Description D-bifunctional protein deficiency is a disorder that causes ...

  7. Analyzing the Case for Bifunctional Catalysis.

    PubMed

    Andersen, Mie; Medford, Andrew J; Nørskov, Jens K; Reuter, Karsten

    2016-04-18

    Bifunctional coupling of two different catalytic site types has often been invoked to explain experimentally observed enhanced catalytic activities. We scrutinize such claims with generic scaling-relation-based microkinetic models that allow exploration of the theoretical limits for such a bifunctional gain for several model reactions. For sites at transition-metal surfaces, the universality of the scaling relations between adsorption energies largely prevents any improvements through bifunctionality. Only the consideration of systems that involve the combination of different materials, such as metal particles on oxide supports, offers hope for significant bifunctional gains. PMID:27005967

  8. Bifunctional Phosphorus Dendrimers and Their Properties.

    PubMed

    Caminade, Anne-Marie; Majoral, Jean-Pierre

    2016-01-01

    Dendrimers are hyperbranched and monodisperse macromolecules, generally considered as a special class of polymers, but synthesized step-by-step. Most dendrimers have a uniform structure, with a single type of terminal function. However, it is often desirable to have at least two different functional groups. This review will discuss the case of bifunctional phosphorus-containing dendrimers, and the consequences for their properties. Besides the terminal functions, dendritic structures may have also a function at the core, or linked off-center to the core, or at the core of dendrons (dendritic wedges). Association of two dendrons having different terminal functions leads to Janus dendrimers (two faces). The internal structure can also possess functional groups on one layer, or linked to one layer, or on several layers. Finally, there are several ways to have two types of terminal functions, besides the case of Janus dendrimers: either each terminal function bears two functions sequentially, or two different functions are linked to each terminal branching point. Examples of each type of structure will be given in this review, as well as practical uses of such sophisticated structures in the fields of fluorescence, catalysis, nanomaterials and biology. PMID:27120586

  9. Simple activation by acid of latent Ru-NHC-based metathesis initiators bearing 8-quinolinolate co-ligands

    PubMed Central

    Wappel, Julia; Fischer, Roland C; Cavallo, Luigi; Slugovc, Christian

    2016-01-01

    Summary A straightforward synthesis utilizing the ring-opening metathesis polymerization (ROMP) reaction is described for acid-triggered N,O-chelating ruthenium-based pre-catalysts bearing one or two 8-quinolinolate ligands. The innovative pre-catalysts were tested regarding their behavior in ROMP and especially for their use in the synthesis of poly(dicyclopentadiene) (pDCPD). Bearing either the common phosphine leaving ligand in the first and second Grubbs olefin metathesis catalysts, or the Ru–O bond cleavage for the next Hoveyda-type catalysts, this work is a step forward towards the control of polymer functionalization and living or switchable polymerizations. PMID:26877818

  10. 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 μm 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. α 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 α spectrometry using the absolute efficiency at a fixed counting geometry. The analytical performance of the membrane-supported-bifunctional-polymer-based α spectrometry method was found to be highly reproducible for assay of Pu(IV) in a variety of complex samples. PMID:24901969

  11. A bifunctional chiral [2]catenane based on 1,1'-binaphthyl-phosphates.

    PubMed

    Mitra, R; Thiele, M; Octa-Smolin, F; Letzel, M C; Niemeyer, J

    2016-05-21

    A novel [2]catenane was synthesised by ring-closing metathesis from a Ca-bisphosphate template. The resulting interlocked structure features two chiral 1,1'-binaphthyl-phosphates, leading to a bifunctional catenane structure. Initial binding studies point at the applicability of such mechanically interlocked bisphosphates as artificial receptors for dicationic guest molecules. PMID:27058367

  12. Bearing system

    DOEpatents

    Kapich, Davorin D.

    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.

  13. 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.

  14. Bifunctional hydrogen bonds in monohydrated cycloether complexes.

    PubMed

    Vallejos, Margarita M; Angelina, Emilio L; Peruchena, Nélida M

    2010-03-01

    In this work, the cooperative effects implicated in bifunctional hydrogen bonds (H-bonds) were studied (in monohydrated six-membered cycloether) within the framework of the atoms in molecules (AIM) theory and of the natural bond orbitals (NBO) analysis. The study was carried out in complexes formed by six-membered cycloether compounds (tetrahydropyrane, 1,4-dioxane, and 1,3-dioxane) and a water molecule. These compounds were used as model systems instead of more complicated molecules of biological importance. All the results were obtained at the second-order Møller-Plesset (MP2) level theory using a 6-311++G(d,p) basis set. Attention was focused on the indicators of the cooperative effects that arise when a water molecule interacts simultaneously with a polar and a nonpolar portion of a six-membered cycloether (via bifunctional hydrogen bonds) and compared with conventional H-bonds where the water molecule only interacts with the polar portion of the cycloether. Different indicators of H-bonds strength, such as structural and spectroscopic data, electron charge density, population analysis, hyperconjugation energy and charge transference, consistently showed significant cooperative effects in bifunctional H-bonds. From the AIM, as well as from the NBO analysis, the obtained results allowed us to state that in the monohydrated six-membered cycloether, where the water molecule plays a dual role, as proton acceptor and proton donor, a mutual reinforcement of the two interactions occurs. Because of this feature, the complexes engaged by bifunctional hydrogen bonds are more stabilized than the complexes linked by conventional hydrogen bonds. PMID:20136161

  15. THRUST BEARING

    DOEpatents

    Heller, P.R.

    1958-09-16

    A thrust bearing suitable for use with a rotor or blower that is to rotate about a vertical axis is descrihed. A centrifagal jack is provided so thnt the device may opernte on one hearing at starting and lower speeds, and transfer the load to another bearing at higher speeds. A low viscosity fluid is used to lubricate the higher speed operation bearing, in connection with broad hearing -surfaces, the ability to withstand great loads, and a relatively high friction loss, as contraated to the lower speed operatio;n bearing which will withstand only light thrust loads but is sufficiently frictionfree to avoid bearing seizure during slow speed or startup operation. An axially aligned shaft pin provides the bearing surface for low rotational speeds, but at higher speed, weights operating against spring tension withdraw nthe shaft pin into the bearing proper and the rotor shaft comes in contact with the large bearing surfaces.

  16. 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

  17. Journal bearing

    DOEpatents

    Menke, John R.; Boeker, Gilbert F.

    1976-05-11

    1. An improved journal bearing comprising in combination a non-rotatable cylindrical bearing member having a first bearing surface, a rotatable cylindrical bearing member having a confronting second bearing surface having a plurality of bearing elements, a source of lubricant adjacent said bearing elements for supplying lubricant thereto, each bearing element consisting of a pair of elongated relatively shallowly depressed surfaces lying in a cylindrical surface co-axial with the non-depressed surface and diverging from one another in the direction of rotation and obliquely arranged with respect to the axis of rotation of said rotatable member to cause a flow of lubricant longitudinally along said depressed surfaces from their distal ends toward their proximal ends as said bearing members are rotated relative to one another, each depressed surface subtending a radial angle of less than 360.degree., and means for rotating said rotatable bearing member to cause the lubricant to flow across and along said depressed surfaces, the flow of lubricant being impeded by the non-depressed portions of said second bearing surface to cause an increase in the lubricant pressure.

  18. 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.

  19. Bifunctional Gallium-68 Chelators: Past, Present, and Future.

    PubMed

    Spang, Philipp; Herrmann, Christian; Roesch, Frank

    2016-09-01

    This article reviews the development of bifunctional chelates for synthesising (68)Ga radiopharmaceuticals. It structures the chelates into groups of macrocycles, nonmacrocycles, and chimeric derivatives. The most relevant bifunctional chelates are discussed in chelate structure, parameters of (68)Ga-labeling, and stability of the (68)Ga-chelate complexes. Furthermore those derivatives are included, where (67)Ga was applied instead of (68)Ga. A particular feature discussed is the ability of certain bifunctional chelate structures to function in kit-type preparation of the (68)Ga radiopharmaceuticals. Currently, nonmacrocyclic and chimeric derivates attract particular attention such as THP-derivates and DATA-derivates. PMID:27553464

  20. Particle migration through sealed bearings

    SciTech Connect

    Sundvold, P.D.

    1993-08-01

    Tests were performed to determine the ability of various types of shielded bearings to isolate particulate from a clean environment in support of the Direct Optical Initiation (DOI) program. In the DOI firing system, a stronglink mechanism will share the same environment with a high-powered laser which needs uncontaminated optics to perform properly. Two commercially available shielded and sealed bearings were tested along with a sealed bearing designed at Allied Signal Inc., Kansas City Division (KCD). The KCD-designed bearing proved to be the best barrier, but the torque required to function the bearing was magnitudes above the commercial bearings. The commercial sealed bearing was an effective barrier, allowing a small fraction of particles to migrate through, and had a relatively low running torque. The shielded bearing was not acceptable as a particle barrier.

  1. Grizzly bear

    USGS Publications Warehouse

    Schwartz, C.C.; Miller, S.D.; Haroldson, M.A.

    2003-01-01

    The grizzly bear inspires fear, awe, and respect in humans to a degree unmatched by any other North American wild mammal. Like other bear species, it can inflict serious injury and death on humans and sometimes does. Unlike the polar bear (Ursus maritimus) of the sparsely inhabited northern arctic, however, grizzly bears still live in areas visited by crowds of people, where presence of the grizzly remains physically real and emotionally dominant. A hike in the wilderness that includes grizzly bears is different from a stroll in a forest from which grizzly bears have been purged; nighttime conversations around the campfire and dreams in the tent reflect the presence of the great bear. Contributing to the aura of the grizzly bear is the mixture of myth and reality about its ferocity. unpredictable disposition, large size, strength, huge canines, long claws, keen senses, swiftness, and playfulness. They share characteristics with humans such as generalist life history strategies. extended periods of maternal care, and omnivorous diets. These factors capture the human imagination in ways distinct from other North American mammals. Precontact Native American legends reflected the same fascination with the grizzly bear as modern stories and legends (Rockwell 1991).

  2. 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.

  3. Bifunctional Ligands Allow Deliberate Extrinsic Reprogramming of the Glucocorticoid Receptor

    PubMed Central

    Højfeldt, Jonas W.; Cruz-Rodríguez, Osvaldo; Imaeda, Yasuhiro; Van Dyke, Aaron R.; Carolan, James P.; Mapp, Anna K.

    2014-01-01

    Therapies based on conventional nuclear receptor ligands are extremely powerful, yet their broad and long-term use is often hindered by undesired side effects that are often part of the receptor's biological function. Selective control of nuclear receptors such as the glucocorticoid receptor (GR) using conventional ligands has proven particularly challenging. Because they act solely in an allosteric manner, conventional ligands are constrained to act via cofactors that can intrinsically partner with the receptor. Furthermore, effective means to rationally encode a bias for specific coregulators are generally lacking. Using the (GR) as a framework, we demonstrate here a versatile approach, based on bifunctional ligands, that extends the regulatory repertoire of GR in a deliberate and controlled manner. By linking the macrolide FK506 to a conventional agonist (dexamethasone) or antagonist (RU-486), we demonstrate that it is possible to bridge the intact receptor to either positively or negatively acting coregulatory proteins bearing an FK506 binding protein domain. Using this strategy, we show that extrinsic recruitment of a strong activation function can enhance the efficacy of the full agonist dexamethasone and reverse the antagonist character of RU-486 at an endogenous locus. Notably, the extrinsic recruitment of histone deacetylase-1 reduces the ability of GR to activate transcription from a canonical GR response element while preserving ligand-mediated repression of nuclear factor-κB. By providing novel ways for the receptor to engage specific coregulators, this unique ligand design approach has the potential to yield both novel tools for GR study and more selective therapeutics. PMID:24422633

  4. Organocatalytic One-Pot Asymmetric Synthesis of Thiolated Spiro-γ-lactam Oxindoles Bearing Three Stereocenters.

    PubMed

    Huang, Xin; Liu, Miao; Pham, Kenny; Zhang, Xiaofeng; Yi, Wen-Bin; Jasinski, Jerry P; Zhang, Wei

    2016-07-01

    The first asymmetric synthesis of spiro-γ-lactam oxindoles bearing three stereocenters is reported. One-pot thiol-Michael/Mannich/lactamization reactions promoted by a recyclable fluorous bifunctional cinchona alkaloid/thiourea organocatalyst afford products in moderate to good yields with up to 95% ee and 6:1 dr. PMID:27258150

  5. 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.

  6. Nanoparticle Superlattices as Efficient Bifunctional Electrocatalysts for Water Splitting.

    PubMed

    Li, Jun; Wang, Yongcheng; Zhou, Tong; Zhang, Hui; Sun, Xuhui; Tang, Jing; Zhang, Lijuan; Al-Enizi, Abdullah M; Yang, Zhongqin; Zheng, Gengfeng

    2015-11-18

    The solar-driven water splitting process is highly attractive for alternative energy utilization, while developing efficient, earth-abundant, bifunctional catalysts for both oxygen evolution reaction and hydrogen evolution reaction has remained as a major challenge. Herein, we develop an ordered CoMnO@CN superlattice structure as an efficient bifunctional water-splitting electrocatalyst, in which uniform Co-Mn oxide (CoMnO) nanoparticles are coated with a thin, continuous nitrogen-doped carbon (CN) framework. The CoMnO nanoparticles enable optimized OER activity with effective electronic structure configuration, and the CN framework serves as an excellent HER catalyst. Importantly, the ordered superlattice structure is beneficial for enhanced reactive sites, efficient charge transfer, and structural stability. This bifunctional superlattice catalyst manifests optimized current densities and electrochemical stability in overall water splitting, outperforming most of the previously reported single- or bifunctional electrocatalysts. Combining with a silicon photovoltaic cell, this CoMnO@CN superlattice bifunctional catalyst enables unassisted solar water splitting continuously for ∼5 days with a solar-to-hydrogen conversion efficiency of ∼8.0%. Our discovery suggests that these transition metal oxide-based superlattices may serve as a unique structure modality for efficient bifunctional water splitting electrocatalysts with scale-up potentials. PMID:26496655

  7. 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.

  8. 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

  9. 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.

  10. Seismic bearing

    NASA Astrophysics Data System (ADS)

    Power, Dennis

    2009-05-01

    Textron Systems (Textron) has been using geophones for target detection for many years. This sensing capability was utilized for detection and classification purposes only. Recently Textron has been evaluating multiaxis geophones to calculate bearings and track targets more specifically personnel. This capability will not only aid the system in locating personnel in bearing space or cartesian space but also enhance detection and reduce false alarms. Textron has been involved in the testing and evaluation of several sensors at multiple sites. One of the challenges of calculating seismic bearing is an adequate signal to noise ratio. The sensor signal to noise ratio is a function of sensor coupling to the ground, seismic propagation and range to target. The goals of testing at multiple sites are to gain a good understanding of the maximum and minimum ranges for bearing and detection and to exploit that information to tailor sensor system emplacement to achieve desired performance. Test sites include 10A Site Devens, MA, McKenna Airfield Ft. Benning, GA and Yuma Proving Ground Yuma, AZ. Geophone sensors evaluated include a 28 Hz triax spike, a 15 Hz triax spike and a hybrid triax spike consisting of a 10 Hz vertical geophone and two 28 Hz horizontal geophones. The algorithm uses raw seismic data to calculate the bearings. All evaluated sensors have triaxial geophone configuration mounted to a spike housing/fixture. The suite of sensors also compares various types of geophones to evaluate benefits in lower bandwidth. The data products of these tests include raw geophone signals, seismic features, seismic bearings, seismic detection and GPS position truth data. The analyses produce Probability of Detection vs range, bearing accuracy vs range, and seismic feature level vs range. These analysis products are compared across test sites and sensor types.

  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. Interdomain communications in bifunctional enzymes: how are different activities coordinated?

    PubMed

    Nagradova, Natalya

    2003-08-01

    Although bifunctional enzymes containing two different active centers located within separate domains are quite common in living systems, the significance of this bifunctionality is not always clear, and the molecular mechanisms of site-site interactions in such complex systems have come under the scrutiny of science only in recent years. This review summarizes recent data on the mechanisms of communication between active centers in bifunctional enzymes. Three types of enzymes are considered: (1) those catalyzing consecutive reactions of a metabolic pathway and exhibiting substrate channeling (glutamate synthase and imidazole glycerol phosphate synthase), (2) those catalyzing consecutive reactions without substrate channeling (lysine-ketoglutarate reductase/saccharopine dehydrogenase), and (3) those catalyzing opposed reactions (6-phosphofructo-2-kinase/fructose-2,6-bisphosphatase). The functional role of interdomain communications is briefly discussed. PMID:14609201

  13. Strategies for the preparation of bifunctional gadolinium(III) chelators

    PubMed Central

    Frullano, Luca; Caravan, Peter

    2012-01-01

    The development of gadolinium chelators that can be easily and readily linked to various substrates is of primary importance for the development high relaxation efficiency and/or targeted magnetic resonance imaging (MRI) contrast agents. Over the last 25 years a large number of bifunctional chelators have been prepared. For the most part, these compounds are based on ligands that are already used in clinically approved contrast agents. More recently, new bifunctional chelators have been reported based on complexes that show a more potent relaxation effect, faster complexation kinetics and in some cases simpler synthetic procedures. This review provides an overview of the synthetic strategies used for the preparation of bifunctional chelators for MRI applications. PMID:22375102

  14. Novel bifunctional natriuretic peptides as potential therapeutics.

    PubMed

    Dickey, Deborah M; Burnett, John C; Potter, Lincoln R

    2008-12-12

    Synthetic atrial natriuretic peptide (carperitide) and B-type natriuretic peptide (BNP; nesiritide) are used to treat congestive heart failure. However, despite beneficial cardiac unloading properties, reductions in renal perfusion pressures limit their clinical effectiveness. Recently, CD-NP, a chimeric peptide composed of C-type natriuretic peptide (CNP) fused to the C-terminal tail of Dendroaspis natriuretic peptide (DNP), was shown to be more glomerular filtration rate-enhancing than BNP in dogs. However, the molecular basis for the increased responsiveness was not determined. Here, we show that the DNP tail has a striking effect on CNP, converting it from a non-agonist to a partial agonist of natriuretic peptide receptor (NPR)-A while maintaining the ability to activate NPR-B. This effect is specific for human receptors because CD-NP was only a slightly better activator of rat NPR-A due to the promiscuous nature of CNP in this species. Interesting, the DNP tail alone had no effect on any NPR even though it is effective in vivo. To further increase the potency of CD-NP for NPR-A, we converted two different triplet sequences within the CNP ring to their corresponding residues in BNP. Both variants demonstrated increased affinity and full agonist activity for NPR-A, whereas one was as potent as any NPR-A activator known. In contrast to a previous report, we found that DNP binds the natriuretic peptide clearance receptor (NPR-C). However, none of the chimeric peptides bound NPR-C with significantly higher affinity than endogenous ligands. We suggest that bifunctional chimeric peptides represent a new generation of natriuretic peptide therapeutics. PMID:18940797

  15. Novel Bifunctional Natriuretic Peptides as Potential Therapeutics*

    PubMed Central

    Dickey, Deborah M.; Burnett, John C.; Potter, Lincoln R.

    2008-01-01

    Synthetic atrial natriuretic peptide (carperitide) and B-type natriuretic peptide (BNP; nesiritide) are used to treat congestive heart failure. However, despite beneficial cardiac unloading properties, reductions in renal perfusion pressures limit their clinical effectiveness. Recently, CD-NP, a chimeric peptide composed of C-type natriuretic peptide (CNP) fused to the C-terminal tail of Dendroaspis natriuretic peptide (DNP), was shown to be more glomerular filtration rate-enhancing than BNP in dogs. However, the molecular basis for the increased responsiveness was not determined. Here, we show that the DNP tail has a striking effect on CNP, converting it from a non-agonist to a partial agonist of natriuretic peptide receptor (NPR)-A while maintaining the ability to activate NPR-B. This effect is specific for human receptors because CD-NP was only a slightly better activator of rat NPR-A due to the promiscuous nature of CNP in this species. Interesting, the DNP tail alone had no effect on any NPR even though it is effective in vivo. To further increase the potency of CD-NP for NPR-A, we converted two different triplet sequences within the CNP ring to their corresponding residues in BNP. Both variants demonstrated increased affinity and full agonist activity for NPR-A, whereas one was as potent as any NPR-A activator known. In contrast to a previous report, we found that DNP binds the natriuretic peptide clearance receptor (NPR-C). However, none of the chimeric peptides bound NPR-C with significantly higher affinity than endogenous ligands. We suggest that bifunctional chimeric peptides represent a new generation of natriuretic peptide therapeutics. PMID:18940797

  16. 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 (α1R,α4R,α7R,α10R)-α1,α4,α7,α10-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

  17. Reaction Current Phenomenon in Bifunctional Catalytic Metal-Semiconductor Nanostructures

    NASA Astrophysics Data System (ADS)

    Hashemian, Mohammad Amin

    Energy transfer processes accompany every elementary step of catalytic chemical processes on material surface including molecular adsorption and dissociation on atoms, interactions between intermediates, and desorption of reaction products from the catalyst surface. Therefore, detailed understanding of these processes on the molecular level is of great fundamental and practical interest in energy-related applications of nanomaterials. Two main mechanisms of energy transfer from adsorbed particles to a surface are known: (i) adiabatic via excitation of quantized lattice vibrations (phonons) and (ii) non-adiabatic via electronic excitations (electron/hole pairs). Electronic excitations play a key role in nanocatalysis, and it was recently shown that they can be efficiently detected and studied using Schottky-type catalytic nanostructures in the form of measureable electrical currents (chemicurrents) in an external electrical circuit. These nanostructures typically contain an electrically continuous nanocathode layers made of a catalytic metal deposited on a semiconductor substrate. The goal of this research is to study the direct observations of hot electron currents (chemicurrents) in catalytic Schottky structures, using a continuous mesh-like Pt nanofilm grown onto a mesoporous TiO2 substrate. Such devices showed qualitatively different and more diverse signal properties, compared to the earlier devices using smooth substrates, which could only be explained on the basis of bifunctionality. In particular, it was necessary to suggest that different stages of the reaction are occurring on both phases of the catalytic structure. Analysis of the signal behavior also led to discovery of a formerly unknown (very slow) mode of the oxyhydrogen reaction on the Pt/TiO2(por) system occurring at room temperature. This slow mode was producing surprisingly large stationary chemicurrents in the range 10--50 microA/cm2. Results of the chemicurrent measurements for the bifunctional

  18. System for testing bearings

    NASA Astrophysics Data System (ADS)

    Gibson, John C.

    1993-07-01

    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.

  19. Bifunctional mesoporous silicas with clearly distinguished localization of grafted groups

    NASA Astrophysics Data System (ADS)

    Roik, N. V.; Belyakova, L. A.

    2013-12-01

    Bifunctional mesoporous silicas with clearly distinguished localization of grafted groups on the surface of particles and inside their pores were obtained by means of sol-gel synthesis with postsynthetic vapor-phase treatment in vacuum. It was found that the synthesized materials have the hexagonally ordered porous structure typical of MCM-41 type silica.

  20. CUSHIONED BEARING

    DOEpatents

    Rushing, F.C.

    1960-09-01

    A vibration damping device effective to dampen vibrations occurring at the several critical speeds encountered in the operation of a high-speed centrifuge is described. A self-centering bearing mechanism is used to protect both the centrifuge shaft and the damping mechanism. The damping mechanism comprises spaced-apant, movable, and stationary sleeve members arranged concentrically of a rotating shaft with a fluid maintained between the members. The movable sleeve member is connected to the shaft for radial movement therewith.

  1. Tooling Converts Stock Bearings To Custom Bearings

    NASA Technical Reports Server (NTRS)

    Fleenor, E. N., Jr.

    1983-01-01

    Technique for reworking stock bearings saves time and produces helicopter-rotor bearings ground more precisely. Split tapered ring at one end of threaded bolt expands to hold inside of inner race bearing assembly; nut, at other end of bolt, adjusts amount of spring tension. Piece of hardware grasps bearing firmly without interfering with grinding operation. Operation produces bearing of higher quality than commercially available bearings.

  2. Synthesis and structures of tridentate ketoiminate zinc complexes bearing trifluoromethyl substituents that act as L-lactide ring opening polymerization initiators.

    PubMed

    Rezayee, Nomaan M; Gerling, Kimberly A; Rheingold, Arnold L; Fritsch, Joseph M

    2013-04-21

    A series of NNO ketoimines bearing trifluoromethyl substituents were synthesized from the Schiff base condensation of 1,3-diketones (1,1,1-trifluoro-5,5-dimethyl-2,4-hexanedione, 4,4,4-trifluoro-1-phenyl-1,3-butanedione, and 1,1,1-trifluoro-2,4-pentanedione, 1,1,1,5,5,5-hexafluoroacetylacetone) and 8-aminoquinoline or 8-amino-2-methylquinoline and isolated in 40-70% yield. The ketoimines were combined with zinc bis-(trimethylsilyl)amide to prepare a zinc amide complex in 41% yield or were combined with zinc bis-(trimethylsilyl)amide and 2,6-di-tert-butylphenol to prepare zinc phenoxide complexes in 81-94% yield. The ketoimines and zinc complexes were characterized with (1)H, (13)C, and (19)F NMR, absorbance spectroscopy, mass spectrometry, elemental analysis and X-ray crystallography. The mononuclear solid state structures of the zinc amide and phenoxide complexes showed tridentate coordination of the zinc center by the ketoiminate and monodentate coordination by the amide or phenoxide. The zinc complexes were assessed for their ability to catalyze the ring opening polymerization (ROP) of L-lactide into poly-lactic acid (PLA) with some complexes reaching 100% conversion in 3 h. As the monomer to catalyst ratio increased, the molecular weight of the isolated polymeric material increased in a nearly linear fashion while retaining a narrow molecular weight distribution. Homonuclear decoupled (1)H NMR spectra of the isolated polymeric material showed the retention of stereochemistry in the isotactic poly-L-lactic acid. Kinetic studies, where the substituents on the ketoiminate and quinolyl moiety were varied, showed that lower electron density on the Zn metal center yielded lower ROP catalytic activity than their electron rich counterparts. The complexes are proposed to use the coordination-insertion mechanism for living polymerization of L-lactide. PMID:23435405

  3. Fluid lubricated bearing construction

    DOEpatents

    Dunning, John R.; Boorse, Henry A.; Boeker, Gilbert F.

    1976-01-01

    1. A fluid lubricated thrust bearing assembly comprising, in combination, a first bearing member having a plain bearing surface, a second bearing member having a bearing surface confronting the bearing surface of said first bearing member and provided with at least one spiral groove extending inwardly from the periphery of said second bearing member, one of said bearing members having an axial fluid-tight well, a source of fluid lubricant adjacent to the periphery of said second bearing member, and means for relatively rotating said bearing members to cause said lubricant to be drawn through said groove and to flow between said bearing surfaces, whereby a sufficient pressure is built up between said bearing surfaces and in said well to tend to separate said bearing surfaces.

  4. Glutathione production by recombinant Escherichia coli expressing bifunctional glutathione synthetase.

    PubMed

    Wang, Dezheng; Wang, Cheng; Wu, Hui; Li, Zhimin; Ye, Qin

    2016-01-01

    Glutathione (GSH) is an important bioactive substance applied widely in pharmaceutical and food industries. Due to the strong product inhibition in the GSH biosynthetic pathway, high levels of intracellular content, yield and productivity of GSH are difficult to achieve. Recently, a novel bifunctional GSH synthetase was identified to be less sensitive to GSH. A recombinant Escherichia coli strain expressing gshF encoding the bifunctional glutathione synthetase of Streptococcus thermophilus was constructed for GSH production. In this study, efficient GSH production using this engineered strain was investigated. The cultivation process was optimized by controlling dissolved oxygen (DO), amino acid addition and glucose feeding. 36.8 mM (11.3 g/L) GSH were formed at a productivity of 2.06 mM/h when the amino acid precursors (75 mM each) were added and glucose was supplied as the sole carbon and energy source. PMID:26586402

  5. Bifunctional organophosphorus liquid-liquid extraction reagents: development and applications

    SciTech Connect

    Schulz, W.W.; Navratil, J.D.

    1985-01-01

    American and Russian workers have evidenced great interest in the last decade in the potential application of certain neutral and acidic bifunctional organophosphorus compounds in solvent extraction processes. Triggering this interest is the ability of some carbamoylmethylenephosphorus (CMP) and carbamoylmethylenephosphine oxide (CMPO) compounds to extract trivalent actinides and lanthanides from strong HNO/sub 3/ (>1 M) solutions, a property which distinguishes them from monofunctional organophosphorus reagents. Investigators at several US Department of Energy laboratories have concentrated on synthesis of novel CMP and CMPO reagents and on reactions and mechanisms involved in extraction of metal ions from aqueous nitrate media; application of selected CMP and CMPO reagents in solvent extraction and supported liquid membrane recovery of metal values from nuclear waste solutions have been proposed. This paper, based upon a book now in preparation, provides a brief overview of the current status of the development and application of bifunctional organophosphorus extractants. 44 references, 4 tables.

  6. Bifunctional organophosphorus liquid-liquid extraction reagents: development and applications

    SciTech Connect

    Schulz, W.W.; Navratil, J.D.

    1984-03-13

    American and Russian workers have evidenced great interest in the last decade in the potential application of certain neutral and acidic bifunctional organophosphorus compounds in solvent extraction processes. Triggering this interest is the ability of some carbamoylmethylenephosphorus (CMP) and carbamoylmethylenephosphine oxide (CMPO) compounds to extract trivalent actinides and lanthanides from strong HNO/sub 3/ (>1M) solutions, a property which distinguishes them from monofunctional organophosphorus reagents. Investigators at several US Department of Energy laboratories have concentrated on synthesis of novel CMP and CMPO reagents and on reactions and mechanisms involved in extraction of metal ions from aqueous nitrate media; application of selected CMP and CMPO reagents in solvent extraction and supported liquid membrane recovery of metal values from nuclear waste solutions have been proposed. This paper, based upon a book now in preparation, provides a brief overview of the current status of the development and application of bifunctional organophosphorus extractants. 42 references, 4 tables.

  7. The aminoindanol core as a key scaffold in bifunctional organocatalysts

    PubMed Central

    G. Sonsona, Isaac

    2016-01-01

    Summary The 1,2-aminoindanol scaffold has been found to be very efficient, enhancing the enantioselectivity when present in organocatalysts. This may be explained by its ability to induce a bifunctional activation of the substrates involved in the reaction. Thus, it is easy to find hydrogen-bonding organocatalysts ((thio)ureas, squaramides, quinolinium thioamide, etc.) in the literature containing this favored structural core. They have been successfully employed in reactions such as Friedel–Crafts alkylation, Michael addition, Diels–Alder and aza-Henry reactions. However, the 1,2-aminoindanol core incorporated into proline derivatives has been scarcely explored. Herein, the most representative and illustrative examples are compiled and this review will be mainly focused on the cases where the aminoindanol moiety confers bifunctionality to the organocatalysts. PMID:27340443

  8. The aminoindanol core as a key scaffold in bifunctional organocatalysts.

    PubMed

    G Sonsona, Isaac; Marqués-López, Eugenia; Herrera, Raquel P

    2016-01-01

    The 1,2-aminoindanol scaffold has been found to be very efficient, enhancing the enantioselectivity when present in organocatalysts. This may be explained by its ability to induce a bifunctional activation of the substrates involved in the reaction. Thus, it is easy to find hydrogen-bonding organocatalysts ((thio)ureas, squaramides, quinolinium thioamide, etc.) in the literature containing this favored structural core. They have been successfully employed in reactions such as Friedel-Crafts alkylation, Michael addition, Diels-Alder and aza-Henry reactions. However, the 1,2-aminoindanol core incorporated into proline derivatives has been scarcely explored. Herein, the most representative and illustrative examples are compiled and this review will be mainly focused on the cases where the aminoindanol moiety confers bifunctionality to the organocatalysts. PMID:27340443

  9. Cryogenic turbopump bearing materials

    NASA Technical Reports Server (NTRS)

    Bhat, Biliyar N.

    1989-01-01

    Materials used for modern cryogenic turbopump bearings must withstand extreme conditions of loads and speeds under marginal lubrication. Naturally, these extreme conditions tend to limit the bearing life. It is possible to significantly improve the life of these bearings, however, by improving the fatigue and wear resistance of bearing alloys, and improving the strength, liquid oxygen compatibility and lubricating ability of the bearing cage materials. Improved cooling will also help to keep the bearing temperatures low and hence prolong the bearing life.

  10. Bifunctional air electrodes containing elemental iron powder charging additive

    DOEpatents

    Liu, Chia-tsun; Demczyk, Brian G.; Gongaware, Paul R.

    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.

  11. Room Temperature Hydrosilylation of Silicon Nanocrystals with Bifunctional Terminal Alkenes

    PubMed Central

    Yu, Yixuan; Hessel, Colin M.; Bogart, Timothy; Panthani, Matthew G.; Rasch, Michael R.; Korgel, Brian A.

    2013-01-01

    H-terminated Si nanocrystals undergo room temperature hydrosilylation with bifunctional alkenes with distal polar moieties—ethyl-, methyl-ester or carboxylic acids—without the aid of light or added catalyst. The passivated Si nanocrystals exhibit bright photoluminescence (PL) and disperse in polar solvents, including water. We propose a reaction mechanism in which ester or carboxylic acid groups facilitate direct nucleophilic attack of the highly curved Si surface of the nanocrystals by the alkene. PMID:23312033

  12. Nanoscale intimacy in bifunctional catalysts for selective conversion of hydrocarbons.

    PubMed

    Zečević, Jovana; Vanbutsele, Gina; de Jong, Krijn P; Martens, Johan A

    2015-12-10

    The ability to control nanoscale features precisely is increasingly being exploited to develop and improve monofunctional catalysts. Striking effects might also be expected in the case of bifunctional catalysts, which are important in the hydrocracking of fossil and renewable hydrocarbon sources to provide high-quality diesel fuel. Such bifunctional hydrocracking catalysts contain metal sites and acid sites, and for more than 50 years the so-called intimacy criterion has dictated the maximum distance between the two types of site, beyond which catalytic activity decreases. A lack of synthesis and material-characterization methods with nanometre precision has long prevented in-depth exploration of the intimacy criterion, which has often been interpreted simply as 'the closer the better' for positioning metal and acid sites. Here we show for a bifunctional catalyst--comprising an intimate mixture of zeolite Y and alumina binder, and with platinum metal controllably deposited on either the zeolite or the binder--that closest proximity between metal and zeolite acid sites can be detrimental. Specifically, the selectivity when cracking large hydrocarbon feedstock molecules for high-quality diesel production is optimized with the catalyst that contains platinum on the binder, that is, with a nanoscale rather than closest intimacy of the metal and acid sites. Thus, cracking of the large and complex hydrocarbon molecules that are typically derived from alternative sources, such as gas-to-liquid technology, vegetable oil or algal oil, should benefit especially from bifunctional catalysts that avoid locating platinum on the zeolite (the traditionally assumed optimal location). More generally, we anticipate that the ability demonstrated here to spatially organize different active sites at the nanoscale will benefit the further development and optimization of the emerging generation of multifunctional catalysts. PMID:26659185

  13. Nanoscale intimacy in bifunctional catalysts for selective conversion of hydrocarbons

    NASA Astrophysics Data System (ADS)

    Zecevic, Jovana; Vanbutsele, Gina; de Jong, Krijn P.; Martens, Johan A.

    2015-12-01

    The ability to control nanoscale features precisely is increasingly being exploited to develop and improve monofunctional catalysts. Striking effects might also be expected in the case of bifunctional catalysts, which are important in the hydrocracking of fossil and renewable hydrocarbon sources to provide high-quality diesel fuel. Such bifunctional hydrocracking catalysts contain metal sites and acid sites, and for more than 50 years the so-called intimacy criterion has dictated the maximum distance between the two types of site, beyond which catalytic activity decreases. A lack of synthesis and material-characterization methods with nanometre precision has long prevented in-depth exploration of the intimacy criterion, which has often been interpreted simply as ‘the closer the better’ for positioning metal and acid sites. Here we show for a bifunctional catalyst—comprising an intimate mixture of zeolite Y and alumina binder, and with platinum metal controllably deposited on either the zeolite or the binder—that closest proximity between metal and zeolite acid sites can be detrimental. Specifically, the selectivity when cracking large hydrocarbon feedstock molecules for high-quality diesel production is optimized with the catalyst that contains platinum on the binder, that is, with a nanoscale rather than closest intimacy of the metal and acid sites. Thus, cracking of the large and complex hydrocarbon molecules that are typically derived from alternative sources, such as gas-to-liquid technology, vegetable oil or algal oil, should benefit especially from bifunctional catalysts that avoid locating platinum on the zeolite (the traditionally assumed optimal location). More generally, we anticipate that the ability demonstrated here to spatially organize different active sites at the nanoscale will benefit the further development and optimization of the emerging generation of multifunctional catalysts.

  14. Nanoscale intimacy in bifunctional catalysts for selective conversion of hydrocarbons

    PubMed Central

    Zečević, Jovana; Vanbutsele, Gina; de Jong, Krijn P.; Martens, Johan A.

    2016-01-01

    The ability to precisely control nanoscale features is increasingly exploited to develop and improve monofunctional catalysts1–4. Striking effects might also be expected in the case of bifunctional catalysts, which play an important role in hydrocracking of fossil and renewable hydrocarbon sources to provide high-quality diesel fuel5–7. Such bifunctional hydrocracking catalysts contain metal sites and acid sites, and for more than 50 years the so-called ‘intimacy criterion’8 has dictated the maximum distance between the two site types beyond which catalytic activity decreases. The lack of synthesis and material characterization methods with nanometer precision has long prevented in-depth exploration of the criterion, which has often been interpreted simply as ‘the closer the better’ for positioning metal and acid sites8–11. Here we show for a bifunctional catalyst, comprised of an intimate mixture of zeolite Y and alumina binder and with platinum (Pt) metal controllably deposited20,21 on either the zeolite or the binder, that close proximity between metal and zeolite acid sites can be detrimental: the selectivity when cracking large hydrocarbon feedstock molecules for high-quality diesel production is optimized with the catalyst that contains Pt on the binder, i.e. with a larger distance between metal and acid sites. Cracking of the large and complex hydrocarbon molecules typically derived from alternative sources such as gas-to-liquid technology, vegetable oil or algal oil6–7 should thus benefit especially from bifunctional catalysts that avoid locating Pt on the zeolite as the traditionally assumed optimal location. More generally, we anticipate that the ability to spatially organize different active sites at the nanoscale demonstrated here will benefit the further development and optimization of the newly emerging generation of multifunctional catalysts12–15. PMID:26659185

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

    PubMed

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

    2014-01-01

    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. PMID:25308055

  16. (Bifunctional chelates of Rh-105, Au-199, and other metallic radionuclides as potential radiotherapeutic agents)

    SciTech Connect

    Not Available

    1991-01-01

    Progress during this period is reported under the following headings: Diethylenetriamine based and related bifunctional chelating agents and their complexation with Rh-105, Au-198, Pd-109, cu-67, In-111, and Co-57; studies of Pd-109, Rh-105 and Tc-99m with bifunctional chelates based on phenylenediamine; establishment of an appropriate protein assay method for conjugated proteins; studies of new bifunctional Bi, Tri and tetradentate amine oxime ligands with Rh-105; IgG and antibody B72.3 conjugation studies by HPLC Techniques with bifunctional metal chelates; and progress on ligand systems for Au(III).

  17. [Bifunctional chelates of Rh-105, Au-199, and other metallic radionuclides as potential radiotherapeutic agents

    SciTech Connect

    Not Available

    1991-12-31

    Progress during this period is reported under the following headings: Diethylenetriamine based and related bifunctional chelating agents and their complexation with Rh-105, Au-198, Pd-109, cu-67, In-111, and Co-57; studies of Pd-109, Rh-105 and Tc-99m with bifunctional chelates based on phenylenediamine; establishment of an appropriate protein assay method for conjugated proteins; studies of new bifunctional Bi, Tri and tetradentate amine oxime ligands with Rh-105; IgG and antibody B72.3 conjugation studies by HPLC Techniques with bifunctional metal chelates; and progress on ligand systems for Au(III).

  18. In vivo kinetics of micronuclei induction by bifunctional alkylating antineoplastics.

    PubMed

    Morales-Ramírez, Pedro; Vallarino-Kelly, Teresita; Cruz-Vallejo, Virginia L; López-Iturbe, Rosario; Alvaro-Delgadillo, Horacio

    2004-05-01

    The aim of the present study was to determine in vivo the kinetics of micronucleated polychromatic erythrocyte (MN-PCE) induction in mice, as an approach for studying the mechanism of micronuclei induction by mitomycin C, cis-diamine dichloroplatinum, busulfan and bis-chloroethylnitrosourea, bifuctional alkylating antineoplastic agents having different patterns of crosslink induction. The kinetics of MN-PCE induction was established by scoring the frequency of MN-PCE in 2000 PCE in peripheral blood, for periods of 8 or 10 h after acute treatment and up to 80 h, with different doses of the agent. The kinetics of MN-PCE induction and particularly the times of maximal induction by different bifunctional alkylating agents were compared with the kinetics previously obtained for ethylnitrosourea, methylnitrosourea and 6-mercaptopurine, agents that cause MN-PCE mainly in the first, second and third divisions after exposure, respectively. The results obtained in the present study allow us to conclude that: (i) bifunctional alkylating agents have very different efficiencies of genotoxic and cytotoxic action; (ii) all assayed bifunctional alkylating agents induced micronuclei during the first cell division, owing to the mistaken repair of primary lesions, e.g. excision; (iii) busulfan and bis-chloroethylnitrosourea showed an additional late mechanism of micronuclei induction, which is expressed at the third division and seems to be related to the mismatch repair process. PMID:15123786

  19. 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

  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. 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.

    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.

  2. Enzymatic 13C Labeling and Multidimensional NMR Analysis of Miltiradiene Synthesized by Bifunctional Diterpene Cyclase in Selaginella moellendorffii*

    PubMed Central

    Sugai, Yoshinori; Ueno, Yohei; Hayashi, Ken-ichiro; Oogami, Shingo; Toyomasu, Tomonobu; Matsumoto, Sadamu; Natsume, Masahiro; Nozaki, Hiroshi; Kawaide, Hiroshi

    2011-01-01

    Diterpenes show diverse chemical structures and various physiological roles. The diversity of diterpene is primarily established by diterpene cyclases that catalyze a cyclization reaction to form the carbon skeleton of cyclic diterpene. Diterpene cyclases are divided into two types, monofunctional and bifunctional cyclases. Bifunctional diterpene cyclases (BDTCs) are involved in hormone and defense compound biosyntheses in bryophytes and gymnosperms, respectively. The BDTCs catalyze the successive two-step type-B (protonation-initiated cyclization) and type-A (ionization-initiated cyclization) reactions of geranylgeranyl diphosphate (GGDP). We found that the genome of a lycophyte, Selaginella moellendorffii, contains six BDTC genes with the majority being uncharacterized. The cDNA from S. moellendorffii encoding a BDTC-like enzyme, miltiradiene synthase (SmMDS), was cloned. The recombinant SmMDS converted GGDP to a diterpene hydrocarbon product with a molecular mass of 272 Da. Mutation in the type-B active motif of SmMDS abolished the cyclase activity, whereas (+)-copalyl diphosphate, the reaction intermediate from the conversion of GGDP to the hydrocarbon product, rescued the cyclase activity of the mutant to form a diterpene hydrocarbon. Another mutant lacking type-A activity accumulated copalyl diphosphate as the reaction intermediate. When the diterpene hydrocarbon was enzymatically synthesized from [U-13C6]mevalonate, all carbons were labeled with 13C stable isotope (>99%). The fully 13C-labeled product was subjected to 13C-13C COSY NMR spectroscopic analyses. The direct carbon-carbon connectivities observed in the multidimensional NMR spectra demonstrated that the hydrocarbon product by SmMDS is miltiradiene, a putative biosynthetic precursor of tanshinone identified from the Chinese medicinal herb Salvia miltiorrhiza. Hence, SmMDS functions as a bifunctional miltiradiene synthase in S. moellendorffii. In this study, we demonstrate that one-dimensional and

  3. Chromium(VI) removal via reduction-sorption on bi-functional silica adsorbents.

    PubMed

    Zaitseva, Nataliya; Zaitsev, Vladimir; Walcarius, Alain

    2013-04-15

    Organically-modified silica gels bearing mercaptopropyl and ethylenediaminetriacetate groups (SiO2-SH/ED3A) have been used for reduction and subsequent sequestration of Cr(VI) species. The uptake mechanism involves Cr(VI) reduction by thiol groups (SH) and further immobilization of the so-generated Cr(III) species via complexation to the ethylenediaminetriacetate moieties (ED3A). The most appropriate pH range (1-3) for complete Cr(VI) reduction-sorption by SiO2-SH/ED3A originates from the balance between full reduction of Cr(VI) by SH, requiring low pH values, and quantitative complexation of Cr(III) by ED3A, which is favored in less acidic media. Such bi-functional adsorbents are considerably more effective at removal of Cr(VI) than those simply modified with thiol groups alone. The whole reduction-sorption process was characterized by fast kinetics, thus permitting efficient use of the SiO2-SH/ED3A adsorbent in dynamic conditions (column experiments). Monitoring the amount of immobilized chromium species on the solid was achieved using X-ray fluorescence spectroscopy and UV-vis spectroscopy. Studying the influence of ionic strength and presence of heavy metals revealed few interference on Cr(VI) removal. PMID:23500426

  4. 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, ...

  5. 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

  6. Hexadentate bispidine derivatives as versatile bifunctional chelate agents for copper(II) radioisotopes.

    PubMed

    Juran, Stefanie; Walther, Martin; Stephan, Holger; Bergmann, Ralf; Steinbach, Jörg; Kraus, Werner; Emmerling, Franziska; Comba, Peter

    2009-02-01

    The preparation and use of bispidine derivatives (3,7-diazabicyclo[3.3.1]nonane) as chelate ligands for radioactive copper isotopes for diagnosis (64Cu) or therapy (67Cu) are reported. Starting from the hexadentate bispidine-based bis(amine)tetrakis(pyridine) ligand 1 with a keto and two ester substituents, the corresponding mono-ol 2 and two dicarboxylic acid derivatives 3 and 5 have been synthesized. A range of techniques, including single-crystal X-ray structure analysis, UV/vis spectroscopy, cyclic voltammetry, thin-layer- (TLC), and high-performance liquid chromatography (HPLC), have been used to characterize the structure and stability of the copper(II)-bispidine complexes. A rapid formation (within 1 min) of stable copper(II)-bispidine complexes under mild conditions (ambient temperature, aqueous solution) has been observed. Challenge experiments of these complexes in the presence of a high excess of competing ligands, such as glutathione, cyclam, or superoxide dismutase (SOD), as well as in rat plasma, gave no evidence of demetalation or transchelation. The bifunctional bispidine derivative 5 can be readily functionalized with biologically active molecules at the pendant carboxylate groups. The coupling of a bombesin analogue betahomo-Glu-betaAla-betaAla-[Cha(13),Nle(14)]BBN(7-14), by condensation of a carboxylate of the bispidine backbone with the N-terminus of the peptide produced the bifunctional ligand 6. The radiocopper(II) complex of this bombesin-bispidine conjugate has a considerable hydrophilicity (log D(o/w) < -2.4), and this leads to a very fast blood clearance (blood: 0.28 +/- 0.02 SUV, 1 h p.i.), low liver tissue accumulation (liver: 1.20 +/- 0.27 SUV, 1 h p.i.), and rapid renal-urinary excretion (kidneys: 6.06 +/- 2.96 SUV, 1 h p.i.) as shown by biodistribution studies of 64Cu-6 in Wistar rats. Preliminary in vivo studies of 64Cu-6 in NMRI nu/nu mice, bearing the human prostate tumor PC-3 showed an accumulation of the conjugate in the tumor (2

  7. 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.

  8. Invariants reveal multiple forms of robustness in bifunctional enzyme systems.

    PubMed

    Dexter, Joseph P; Dasgupta, Tathagata; Gunawardena, Jeremy

    2015-08-01

    Experimental and theoretical studies have suggested that bifunctional enzymes catalyzing opposing modification and demodification reactions can confer steady-state concentration robustness to their substrates. However, the types of robustness and the biochemical basis for them have remained elusive. Here we report a systematic study of the most general biochemical reaction network for a bifunctional enzyme acting on a substrate with one modification site, along with eleven sub-networks with more specialized biochemical assumptions. We exploit ideas from computational algebraic geometry, introduced in previous work, to find a polynomial expression (an invariant) between the steady state concentrations of the modified and unmodified substrate for each network. We use these invariants to identify five classes of robust behavior: robust upper bounds on concentration, robust two-sided bounds on concentration ratio, hybrid robustness, absolute concentration robustness (ACR), and robust concentration ratio. This analysis demonstrates that robustness can take a variety of forms and that the type of robustness is sensitive to many biochemical details, with small changes in biochemistry leading to very different steady-state behaviors. In particular, we find that the widely-studied ACR requires highly specialized assumptions in addition to bifunctionality. An unexpected result is that the robust bounds derived from invariants are strictly tighter than those derived by ad hoc manipulation of the underlying differential equations, confirming the value of invariants as a tool to gain insight into biochemical reaction networks. Furthermore, invariants yield multiple experimentally testable predictions and illuminate new strategies for inferring enzymatic mechanisms from steady-state measurements. PMID:26021467

  9. Optimum bifunctionality in a 2-(2-pyridyl-2-ol)-1,10-phenanthroline based ruthenium complex for transfer hydrogenation of ketones and nitriles: impact of the number of 2-hydroxypyridine fragments.

    PubMed

    Paul, Bhaskar; Chakrabarti, Kaushik; Kundu, Sabuj

    2016-07-01

    Considerable differences in reactivity and selectivity for 2-hydroxypyridine (2-HP) derived ruthenium complexes in transfer hydrogenation are described. Bifunctional Ru(ii)-(phenpy-OH) [phenpy-OH: 2-(2-pyridyl-2-ol)-1,10-phenanthroline] complex () exhibited excellent catalytic activity in transfer hydrogenation (TH) of ketones and nitriles. Notably, in comparison with all the reported 2-hydroxypyridine (2-HP) derived ruthenium complexes in transfer hydrogenation, complex displayed significantly higher activity. Additionally, exploiting the metal-ligand cooperativity in complex , chemoselective TH of ketones was achieved and sterically demanding ketones were readily reduced. An outer-sphere mechanism is proposed for this system as exogenous PPh3 has no significant effect on the rate of this reaction. This is a rare example of a highly active bifunctional Ru(ii) catalyst bearing only one 2-HP unit. PMID:27328031

  10. Cupreines and cupreidines: an established class of bifunctional cinchona organocatalysts.

    PubMed

    Bryant, Laura A; Fanelli, Rossana; Cobb, Alexander J A

    2016-01-01

    Cinchona alkaloids with a free 6'-OH functionality are being increasingly used within asymmetric organocatalysis. This fascinating class of bifunctional catalyst offers a genuine alternative to the more commonly used thiourea systems and because of the different spacing between the functional groups, can control enantioselectivity where other organocatalysts have failed. In the main, this review covers the highlights from the last five years and attempts to show the diversity of reactions that these systems can control. It is hoped that chemists developing asymmetric methodologies will see the value in adding these easily accessible, but underused organocatalysts to their screens. PMID:27340439

  11. Cupreines and cupreidines: an established class of bifunctional cinchona organocatalysts

    PubMed Central

    Bryant, Laura A; Fanelli, Rossana

    2016-01-01

    Summary Cinchona alkaloids with a free 6'-OH functionality are being increasingly used within asymmetric organocatalysis. This fascinating class of bifunctional catalyst offers a genuine alternative to the more commonly used thiourea systems and because of the different spacing between the functional groups, can control enantioselectivity where other organocatalysts have failed. In the main, this review covers the highlights from the last five years and attempts to show the diversity of reactions that these systems can control. It is hoped that chemists developing asymmetric methodologies will see the value in adding these easily accessible, but underused organocatalysts to their screens. PMID:27340439

  12. 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.

  13. Restoration of bearings

    NASA Technical Reports Server (NTRS)

    Parker, R. J.; Zaretsky, E. V.; Hanau, H.

    1977-01-01

    Process consisting of grinding raceways to oversize but original quality condition and installing new oversize balls or bearings restores wornout ball and roller bearings to original quality, thereby doubling their operating life. Evaluations reveal process results in restoration of 90% of replaced bearings at less than 50% of new-bearing costs.

  14. Passive magnetic bearing configurations

    DOEpatents

    Post, Richard F.

    2011-01-25

    A journal bearing provides vertical and radial stability to a rotor of a passive magnetic bearing system when the rotor is not rotating and when it is rotating. In the passive magnetic bearing system, the rotor has a vertical axis of rotation. Without the journal bearing, the rotor is vertically and radially unstable when stationary, and is vertically stable and radially unstable when rotating.

  15. 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.

  16. 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.

  17. 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.

  18. 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: ΔilvA and Δfes. 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 ΔilvA or Δfes. 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

  19. Amino Acid-Derived Bifunctional Phosphines for Enantioselective Transformations.

    PubMed

    Wang, Tianli; Han, Xiaoyu; Zhong, Fangrui; Yao, Weijun; Lu, Yixin

    2016-07-19

    Even though seminal reports on phosphine catalysis appeared in the 1960s, in the last few decades of the past century trivalent phosphines were viewed primarily as useful ligands for transition-metal-mediated processes. The 1990s saw revived interest in using phosphines in organic catalysis, but the key advances in asymmetric phosphine catalysis have all come within the past decade. The uniqueness of phosphine catalysis can be attributed to the high nucleophilicity of the phosphorus atom. In typical phosphine-catalyzed reactions, nucleophilic attacks of the phosphorus atom on electron-deficient multiple bonds create different reactive ylide-type intermediates. When such structurally diverse zwitterionic species react with a variety of suitable substrates, new reaction patterns are often discovered and a diverse array of reactions can be developed. In recent years, substantial progress has been made in the field of asymmetric phosphine catalysis; many new reactions have been discovered, and numerous enantioselective processes have been reported. However, we felt that powerful and versatile phosphine catalysts that can work for a wide range of asymmetric reactions are still lacking. We therefore set our goal to develop a family of easily derived phosphine catalysts that are efficient in asymmetric induction for a broad range of phosphine-mediated transformations. This Account describes our efforts in the past few years on the development of amino acid-based bifunctional phosphines and their applications to enantioselective processes. Building upon our previous success in primary-amine-mediated enamine catalysis, we first established that bifunctional phosphines could be readily prepared from amino acids. In most of our studies, we chose threonine as the key backbone for catalyst development, and threonine-based monoamino acid or dipeptide bifunctional phosphines have displayed remarkable stereochemical control. We began our investigations by demonstrating the

  20. Bi-functional CD22 ligands use multimeric immunoglobulins as protein scaffolds in assembly of immune complexes on B cells

    PubMed Central

    O'Reilly, Mary K.; Collins, Brian E.; Han, Shoufa; Liao, Liang; Rillahan, Cory; Kitov, Pavel I.; Bundle, David R.; Paulson, James C.

    2008-01-01

    CD22 is a B cell specific sialic-acid-binding immunoglobulin-like lectin (Siglec) whose function as a regulator of B cell signaling is modulated by its interaction with glycan ligands bearing the sequence NeuAcα2-6Gal. To date, only highly multivalent polymeric ligands (n=450) have achieved sufficient avidity to bind to CD22 on native B cells. Here we demonstrate that a synthetic bi-functional molecule comprising a ligand of CD22 linked to an antigen (nitrophenol; NP) can use a monoclonal anti-NP-IgM as a decavalent protein scaffold to efficiently drive assembly of IgM-CD22 complexes on the surface of native B cells. Surprisingly, anti-NP antibodies of lower valency, IgA (n =4) and IgG (n =2), were also found to drive complex formation, though with lower avidity. Ligands bearing alternate linkers of variable length and structure were constructed to establish the importance of a minimal length requirement, and versatility in the structural requirement. We show that the ligand drives assembly of IgM complexes exclusively on the surface of B cells and not other classes of white blood cells that do not express CD22, which lends itself to the possibility of targeting B cells in certain hematopoietic malignancies. PMID:18505252

  1. Zinc/air battery R and D research and development of bifunctional oxygen electrode: Tasks I and II, Final report

    SciTech Connect

    Klein, M.; Viswanathan, S.

    1986-12-01

    Studies were conducted of the bifunctional oxygen electrode. The development of a rechargeable metal-oxygen (air) cell has been hampered to a great extent by the lack of a stable and cost effective oxygen electrode capable of use during both charge and discharge. The first type of bifunctional electrode consists of two distinct catalytifc layers. The oxygen reduction catalyst layer containing a supported gold catalyst is in contact with a hydrophilic nickel layer in which evolution of oxygen takes place. Loadings of gold from 0.5 to 1.0 mg/cm/sup 2/ were investigated; carbon, graphite, metal, and spinel oxides were evaluated as substrates. The second part of the research effort was centered on developing a reversible oxygen electrode containing only one catalytic layer for both reduction and evolution of oxygen. The work was directed specifically to the study of perovskite type of oxides with the composition AA/sup 1/BO/sub 3/ where A is an element of the lanthanide series, A/sup 1/ is an alkaline earth metal and B, a first row transition element. Initial polarization data obtained in unscrubbed air gave a value of approximately 200 millivolts vs Hg/HgO reference electrode at a current density of 50 ma/cm/sup 2/. Electrodes were made both by roll-bonding and by pelletizing techniques and tested for polarization and cycle life. This study also indicates the optimum process conditions for the manufacture of oxides and fabrication of electrodes.

  2. 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.

  3. Hybrid bearings for LH2 and LO2 turbopumps

    NASA Technical Reports Server (NTRS)

    Butner, M. F.; Lee, F. C.

    1985-01-01

    Hybrid combinations of hydrostatic and ball bearings can improve bearing performance for liquid hydrogen and liquid oxygen turbopumps. Analytic studies were conducted to optimize hybrid bearing designs for the SSME-type turbopump conditions. A method to empirically determine damping coefficients was devised. Four hybrid bearing configurations were designed, and three were fabricated. Six hybrid and hydrostatic-only bearing configurations will be tested for steady-state and transient performance, and quantification of damping coefficients. The initial tests were conducted with the liquid hydrogen bearing.

  4. Mechanical spin bearings

    NASA Technical Reports Server (NTRS)

    Vranish, John M. (Inventor)

    1998-01-01

    A spin bearing assembly including, a pair of mutually opposing complementary bearing support members having mutually spaced apart bearing support surfaces which may be, for example, bearing races and a set of spin bearings located therebetween. Each spin bearing includes a pair of end faces, a central rotational axis passing through the end faces, a waist region substantially mid-way between the end faces and having a first thickness dimension, and discrete side surface regions located between the waist region and the end faces and having a second thickness dimension different from the first thickness dimension of the waist region and wherein the side surface regions further have respective curvilinear contact surfaces adapted to provide a plurality of bearing contact points on the bearing support members.

  5. 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.

  6. Bifunctional combined aptamer for simultaneous separation and detection of thrombin.

    PubMed

    Bing, Tao; Liu, Xiangjun; Cheng, Xiaohong; Cao, Zehui; Shangguan, Dihua

    2010-02-15

    Here we report on the construction and evaluation of a bifunctional combined aptamer (BCA) that consists of a DNA streptavidin-binding aptamer (SBA), a DNA thrombin-binding aptamer (TBA) and a fluorophore. The BCA adopts a new conformation that is very different from simply linking the conformations of the two individual aptamers together, so that it does not bind to streptavidin in the absence of thrombin. Binding of this novel DNA aptamer to streptavidin is triggered by the thrombin binding and depends on the concentration of thrombin. Meanwhile, fluorescence from the streptavidin captured BCA reflects the quantity of the target molecule in the sample. This aptamer combination strategy based on the SBA holds good potential for applications in simultaneous detection and separation of targets of aptamers or certain DNA and RNA targets. PMID:19959350

  7. Enantioselective tandem reaction over a site-isolated bifunctional catalyst.

    PubMed

    Xu, Jianyou; Cheng, Tanyu; Zhang, Kun; Wang, Ziyun; Liu, Guohua

    2016-05-21

    Construction of a site-isolated heterogeneous catalyst to realize the compatibility of bimetallic complexes for a feasible tandem reaction is a significant challenge in heterogeneous asymmetric catalysis. Herein, taking advantage of yolk-shell-structured mesoporous silica, we assemble an active site-isolated bifunctional catalyst through assembly of organopalladium-functionality into silicate channels as an outer shell and chiral organoruthenium-functionality onto silicate yolk as an inner core, realizing the one-pot enantioselective tandem reaction from Pd-catalyzed Sonogashira coupling to Ru-catalyzed asymmetric transfer hydrogenation. As presented in this study, this tandem Sonogashira coupling-asymmetric transfer hydrogenation of haloacetophenones and arylacetylenes affords various chiral conjugated alkynols with high yields and up to 99% enantioselectivity. Moreover, a catalyst can also be recovered easily and recycled repeatedly, making it an interesting feature in a practical organic transformation. PMID:27063335

  8. 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

  9. BIFUNCTIONAL ALUMINUN: A PERMEABLE BARRIER MATERIAL FOR THE DEGRADATION OF MTBE

    EPA Science Inventory

    Bifunctional aluminum is an innovative remedial material for the treatment of gasoline oxygenates in permeable reactive barriers (PRBs). PRBs represent a promising environmental technology for remediation of groundwater contamination. Although zero-valent metals (ZVM) have been...

  10. Bifunctional chelating agent for the design and development of site specific radiopharmaceuticals and biomolecule conjugation strategy

    DOEpatents

    Katti, Kattesh V.; Prabhu, Kandikere R.; Gali, Hariprasad; Pillarsetty, Nagavara Kishore; Volkert, Wynn A.

    2003-10-21

    There is provided a method of labeling a biomolecule with a transition metal or radiometal in a site specific manner to produce a diagnostic or therapeutic pharmaceutical compound by synthesizing a P.sub.2 N.sub.2 -bifunctional chelating agent intermediate, complexing the intermediate with a radio metal or a transition metal, and covalently linking the resulting metal-complexed bifunctional chelating agent with a biomolecule in a site specific manner. Also provided is a method of synthesizing the --PR.sub.2 containing biomolecules by synthesizing a P.sub.2 N.sub.2 -bifunctional chelating agent intermediate, complexing the intermediate with a radiometal or a transition metal, and covalently linking the resulting radio metal-complexed bifunctional chelating agent with a biomolecule in a site specific manner. There is provided a therapeutic or diagnostic agent comprising a --PR.sub.2 containing biomolecule.

  11. Bifunctional chelates of RH-105 and AU199 as potential radiotherapeutic agents

    SciTech Connect

    Droege, P.

    1997-03-01

    Research is presented on new bifunctional chelating ligand systems with stability on the macroscopic and radiochemical levels. The synthesis of the following complexes are described: rhodium 105, palladium 109, and gold 198.

  12. Supertough Stainless Bearing Steel

    NASA Technical Reports Server (NTRS)

    Olson, Gregory B.

    1995-01-01

    Composition and processing of supertough stainless bearing steel designed with help of computer-aided thermodynamic modeling. Fracture toughness and hardness of steel exceeds those of other bearing steels like 440C stainless bearing steel. Developed for service in fuel and oxidizer turbopumps on Space Shuttle main engine. Because of strength and toughness, also proves useful in other applications like gears and surgical knives.

  13. 1-Way Bearing

    NASA Technical Reports Server (NTRS)

    Vranish, John M. (Inventor)

    2003-01-01

    A one-way bearing is provided having sprags and rolling bearings both disposed between an inner and an outer race. The sprags may comprise three-dimensional sprags for preventing rotation in a non-preferential direction. The roll- ing bearings may comprise thrust rollers for transmitting axial, tilt, and radial loads between the inner and outer races.

  14. Synergistic Interaction within Bifunctional Ruthenium Nanoparticle/SILP Catalysts for the Selective Hydrodeoxygenation of Phenols.

    PubMed

    Luska, Kylie L; Migowski, Pedro; El Sayed, Sami; Leitner, Walter

    2015-12-21

    Ruthenium nanoparticles immobilized on acid-functionalized supported ionic liquid phases (Ru NPs@SILPs) act as efficient bifunctional catalysts in the hydrodeoxygenation of phenolic substrates under batch and continuous flow conditions. A synergistic interaction between the metal sites and acid groups within the bifunctional catalyst leads to enhanced catalytic activities for the overall transformation as compared to the individual steps catalyzed by the separate catalytic functionalities. PMID:26545408

  15. Detection and isolation of nucleic acid sequences using a bifunctional hybridization probe

    DOEpatents

    Lucas, Joe N.; Straume, Tore; Bogen, Kenneth T.

    2000-01-01

    A method for detecting and isolating a target sequence in a sample of nucleic acids is provided using a bifunctional hybridization probe capable of hybridizing to the target sequence that includes a detectable marker and a first complexing agent capable of forming a binding pair with a second complexing agent. A kit is also provided for detecting a target sequence in a sample of nucleic acids using a bifunctional hybridization probe according to this method.

  16. Discovery of Bifunctional Oncogenic Target Inhibitors against Allosteric Mitogen-Activated Protein Kinase (MEK1) and Phosphatidylinositol 3-Kinase (PI3K).

    PubMed

    Van Dort, Marcian E; Hong, Hao; Wang, Hanxiao; Nino, Charles A; Lombardi, Rachel L; Blanks, Avery E; Galbán, Stefanie; Ross, Brian D

    2016-03-24

    The synthesis of a series of single entity, bifunctional MEK1/PI3K inhibitors achieved by covalent linking of structural analogs of the ATP-competitive PI3K inhibitor ZSTK474 and the ATP-noncompetitive MEK inhibitor PD0325901 is described. Inhibitors displayed potent in vitro inhibition of MEK1 (0.015 < IC50 (nM) < 56.7) and PI3K (54 < IC50 (nM) < 341) in enzymatic inhibition assays. Concurrent MEK1 and PI3K inhibition was demonstrated with inhibitors 9 and 14 in two tumor cell lines (A549, D54). Inhibitors produced dose-dependent decreased cell viability similar to the combined administration of equivalent doses of ZSTK474 and PD0325901. In vivo efficacy of 14 following oral administration was demonstrated in D54 glioma and A549 lung tumor bearing mice. Compound 14 showed a 95% and 67% inhibition of tumor ERK1/2 and Akt phosphorylation, respectively, at 2 h postadministration by Western blot analysis, confirming the bioavailability and efficacy of this bifunctional inhibitor strategy toward combined MEK1/PI3K inhibition. PMID:26943489

  17. New Tris(hydroxypyridinone) Bifunctional Chelators Containing Isothiocyanate Groups Provide a Versatile Platform for Rapid One-Step Labeling and PET Imaging with 68Ga3+

    PubMed Central

    2015-01-01

    Two new bifunctional tris(hydroxypyridinone) (THP) chelators designed specifically for rapid labeling with 68Ga have been synthesized, each with pendant isothiocyanate groups and three 1,6-dimethyl-3-hydroxypyridin-4-one groups. Both compounds have been conjugated with the primary amine group of a cyclic integrin targeting peptide, RGD. Each conjugate can be radiolabeled and formulated by treatment with generator-produced 68Ga3+ in over 95% radiochemical yield under ambient conditions in less than 5 min, with specific activities of 60–80 MBq nmol–1. Competitive binding assays and in vivo biodistribution in mice bearing U87MG tumors demonstrate that the new 68Ga3+-labeled THP peptide conjugates retain affinity for the αvβ3 integrin receptor, clear within 1–2 h from circulation, and undergo receptor-mediated tumor uptake in vivo. We conclude that bifunctional THP chelators can be used for simple, efficient labeling of 68Ga biomolecules under mild conditions suitable for peptides and proteins. PMID:26286399

  18. Bearings working group

    NASA Technical Reports Server (NTRS)

    1985-01-01

    The service life of the Space Shuttle Main Engine (SSME) turbomachinery bearings was a predominant factor in engine durability and maintenance problems. Recent data has indicated that bearing life is about one order of magnitude lower than the goal of seven and one-half hours particularly those in the High Pressure Oxidizer Turbopump (HPOTP). Bearing technology, primarily cryogenic turbomachinery bearing technology, is expanded by exploring the life and performance effects of design changes; design concept changes; materials changes; manufacturing technique changes; and lubrication system changes. Each variation is assessed against the current bearing design in full scale cryogenic tests.

  19. 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.

  20. Status of Understanding for Bearing Materials

    NASA Technical Reports Server (NTRS)

    Bamberger, E. N.

    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. 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.

  1. 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.

  2. Bifunctional electro-optical nanoprobe to real-time detect local biochemical processes in single cells.

    PubMed

    Zheng, Xin Ting; Hu, Weihua; Wang, Houxiao; Yang, Hongbin; Zhou, Wei; Li, Chang Ming

    2011-07-15

    A bifunctional electro-optical nanoprobe with integrated nanoring electrode and optical nanotip was fabricated and investigated to simultaneously detect both electrical and optical signals in real-time with high spatial resolution. Concurrent measurements of the oxidant generation and the intracellular antioxidant levels in single cells correlate the stronger oxidant generation with an altered initial antioxidant response in the breast cancer cells in comparison to the normal ones suggesting that the cell malignancy is associated with the strength of oxidative stress, and the higher antioxidant level may be the cause of the drug resistance. While the optical detection indicates the fluctuation of the intracellular redox homeostasis, the chronoamperometric signals allow quantitative real-time detection of the H₂O₂ release and decay. Furthermore, the nanoscale probe enables localized simultaneous detections thus discovering that activated enzymes responsible for the oxidative stress target at specific membrane regions. This method promises applications in study of the dynamics of important physiological processes, and provides the opportunity to unravel the interplay of various signaling pathways. PMID:21632233

  3. 78 FR 76104 - Ball Bearings and Parts Thereof From Japan and the United Kingdom: Notice of Reinstatement of...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-12-16

    ... Roller Bearings, and Spherical Plain Bearings, and Parts Thereof From Japan, 54 FR 20904 (May 15, 1989... Value: Ball Bearings, and Cylindrical Roller Bearings and Parts Thereof From the United Kingdom, 54 FR... Initiation of Five-year (``Sunset'') Reviews, 70 FR 31423 (June 1, 2005), and Certain Bearings From...

  4. Bearings: Technology and needs

    NASA Technical Reports Server (NTRS)

    Anderson, W. J.

    1982-01-01

    A brief status report on bearing technology and present and near-term future problems that warrant research support is presented. For rolling element bearings a material with improved fracture toughness, life data in the low Lambda region, a comprehensive failure theory verified by life data and incorporated into dynamic analyses, and an improved corrosion resistant alloy are perceived as important needs. For hydrodynamic bearings better definition of cavitation boundaries and pressure distributions for squeeze film dampers, and geometry optimization for minimum power loss in turbulent film bearings are needed. For gas film bearings, foil bearing geometries that form more nearly optimum film shapes for maximum load capacity, and more effective surface protective coatings for high temperature operation are needed.

  5. Bearing restoration by grinding

    NASA Technical Reports Server (NTRS)

    Hanau, H.; Parker, R. J.; Zaretsky, E. V.; Chen, S. M.; Bull, H. L.

    1976-01-01

    A joint program was undertaken by the NASA Lewis Research Center and the Army Aviation Systems Command to restore by grinding those rolling-element bearings which are currently being discarded at aircraft engine and transmission overhaul. Three bearing types were selected from the UH-1 helicopter engine (T-53) and transmission for the pilot program. No bearing failures occurred related to the restoration by grinding process. The risk and cost of a bearing restoration by grinding programs was analyzed. A microeconomic impact analysis was performed.

  6. Extending bearing life

    SciTech Connect

    Boyer, D.

    1997-08-01

    Long-term bearing operation cannot be achieved unless proper handling, storage, installation, and maintenance procedures are followed. These factors can shorten--sometimes drastically--expected bearing service life. Failures are generally related to improper lubrication or installation and induced conditions. Most major bearing manufacturers offer technical assistance in inspection, evaluation, and reporting on bearings which have failed in service. Actual percentages associated with each failure category vary, depending on the source, but generally they are 70% from lubrication and installation, 20% from induced factors, and 10% from reaching their fatigue limit or design life. The paper describes lubricant-related failures and procedures for the correct handling, storage, installation, and maintenance.

  7. Linear magnetic bearing

    NASA Technical Reports Server (NTRS)

    Studer, P. A. (Inventor)

    1983-01-01

    A linear magnetic bearing system having electromagnetic vernier flux paths in shunt relation with permanent magnets, so that the vernier flux does not traverse the permanent magnet, is described. Novelty is believed to reside in providing a linear magnetic bearing having electromagnetic flux paths that bypass high reluctance permanent magnets. Particular novelty is believed to reside in providing a linear magnetic bearing with a pair of axially spaced elements having electromagnets for establishing vernier x and y axis control. The magnetic bearing system has possible use in connection with a long life reciprocating cryogenic refrigerator that may be used on the space shuttle.

  8. Robust and intelligent bearing estimation

    SciTech Connect

    Claassen, J.P.

    1998-07-01

    As the monitoring thresholds of global and regional networks are lowered, bearing estimates become more important to the processes which associate (sparse) detections and which locate events. Current methods of estimating bearings from observations by 3-component stations and arrays lack both accuracy and precision. Methods are required which will develop all the precision inherently available in the arrival, determine the measurability of the arrival, provide better estimates of the bias induced by the medium, permit estimates at lower SNRs, and provide physical insight into the effects of the medium on the estimates. Initial efforts have focused on 3-component stations since the precision is poorest there. An intelligent estimation process for 3-component stations has been developed and explored. The method, called SEE for Search, Estimate, and Evaluation, adaptively exploits all the inherent information in the arrival at every step of the process to achieve optimal results. In particular, the approach uses a consistent and robust mathematical framework to define the optimal time-frequency windows on which to make estimates, to make the bearing estimates themselves, and to withdraw metrics helpful in choosing the best estimate(s) or admitting that the bearing is immeasurable. The approach is conceptually superior to current methods, particular those which rely on real values signals. The method has been evaluated to a considerable extent in a seismically active region and has demonstrated remarkable utility by providing not only the best estimates possible but also insight into the physical processes affecting the estimates. It has been shown, for example, that the best frequency at which to make an estimate seldom corresponds to the frequency having the best detection SNR and sometimes the best time interval is not at the onset of the signal. The method is capable of measuring bearing dispersion, thereby withdrawing the bearing bias as a function of frequency

  9. Bioinspired Bifunctional Membrane for Efficient Clean Water Generation.

    PubMed

    Liu, Yang; Lou, Jinwei; Ni, Mengtian; Song, Chengyi; Wu, Jianbo; Dasgupta, Neil P; Tao, Peng; Shang, Wen; Deng, Tao

    2016-01-13

    Solving the problems of water pollution and water shortage is an urgent need for the sustainable development of modern society. Different approaches, including distillation, filtration, and photocatalytic degradation, have been developed for the purification of contaminated water and the generation of clean water. In this study, we explored a new approach that uses solar light for both water purification and clean water generation. A bifunctional membrane consisting of a top layer of TiO2 nanoparticles (NPs), a middle layer of Au NPs, and a bottom layer of anodized aluminum oxide (AAO) was designed and fabricated through multiple filtration processes. Such a design enables both TiO2 NP-based photocatalytic function and Au NP-based solar-driven plasmonic evaporation. With the integration of these two functions into a single membrane, both the purification of contaminated water through photocatalytic degradation and the generation of clean water through evaporation were demonstrated using simulated solar illumination. Such a demonstration should also help open up a new strategy for maximizing solar energy conversion and utilization. PMID:26646606

  10. Gold(I) catalysts with bifunctional P, N ligands.

    PubMed

    Wetzel, Corinna; Kunz, Peter C; Thiel, Indre; Spingler, Bernhard

    2011-08-15

    A series of phosphanes with imidazolyl substituents were prepared as hemilabile PN ligands. The corresponding gold(I) complexes were tested as bifunctional catalysts in the Markovnikov hydration of 1-octyne, as well as in the synthesis of propargylamines by the three component coupling reaction of piperidine, benzaldehyde, and phenylacetylene. While the activity in the hydration of 1-octyne was low, the complexes are potent catalysts for the three component coupling reaction. In homogeneous solution the conversions to the respective propargylamine were considerably higher than under aqueous biphasic conditions. The connectivity of the imidazolyl substituents to the phosphorus atom, their substitution pattern, as well as the number of heteroaromatic substituents have pronounced effects on the catalytic activity of the corresponding gold(I) complexes. Furthermore, formation of polymetallic species with Au(2), Au(3), and Au(4) units has been observed and the solid-state structures of the compounds [(5)(2)Au(3)Cl(2)]Cl and [(3c)(2)Au(4)Cl(2)]Cl(2) (3c = tris(2-isopropylimidazol-4(5)-yl phosphane, 5 = 2-tert-butylimidazol-4(5)-yldiphenyl phosphane) were determined. The gold(I) complexes of imidazol-2-yl phosphane ligands proved to be a novel source for bis(NHC)gold(I) complexes (NHC = N-heterocyclic carbene). PMID:21761834

  11. Identification of a Bifunctional Maize C- and O-Glucosyltransferase*

    PubMed Central

    Falcone Ferreyra, María Lorena; Rodriguez, Eduardo; Casas, María Isabel; Labadie, Guillermo; Grotewold, Erich; Casati, Paula

    2013-01-01

    Flavonoids accumulate in plant vacuoles usually as O-glycosylated derivatives, but several species can also synthesize flavonoid C-glycosides. Recently, we demonstrated that a flavanone 2-hydroxylase (ZmF2H1, CYP93G5) converts flavanones to the corresponding 2-hydroxy derivatives, which are expected to serve as substrates for C-glycosylation. Here, we isolated a cDNA encoding a UDP-dependent glycosyltransferase (UGT708A6), and its activity was characterized by in vitro and in vivo bioconversion assays. In vitro assays using 2-hydroxyflavanones as substrates and in vivo activity assays in yeast co-expressing ZmF2H1 and UGT708A6 show the formation of the flavones C-glycosides. UGT708A6 can also O-glycosylate flavanones in bioconversion assays in Escherichia coli as well as by in vitro assays with the purified recombinant protein. Thus, UGT708A6 is a bifunctional glycosyltransferase that can produce both C- and O-glycosidated flavonoids, a property not previously described for any other glycosyltransferase. PMID:24045947

  12. Bifunctional drugs for the treatment of asthma and chronic obstructive pulmonary disease.

    PubMed

    Page, Clive; Cazzola, Mario

    2014-08-01

    Over the last decade, there has been a steady increase in the use of fixed-dose combinations of drugs for the treatment of a range of diseases, including hypertension, cancer, AIDS, tuberculosis and other infectious diseases. It is now evident that patients with asthma or chronic obstructive pulmonary disease (COPD) can also benefit from the use of fixed-dose combinations, including combinations of a long-acting β2-agonist and an inhaled corticosteroid, and combinations of long-acting β2-agonists and long-acting muscarinic receptor antagonists. In fact, there are now a number of "triple-inhaler" fixed-dose combinations under development, with the first such triple combination having been approved in India. This use of combinations containing drugs with complementary pharmacological actions in the treatment of patients with asthma or COPD has also led to the discovery and development of drugs having two different primary pharmacological actions in the same molecule, which we have called "bifunctional drugs". In this review, we discuss the state of the art of these new bifunctional drugs as novel treatments for asthma and COPD that can be categorised as bifunctional bronchodilators, bifunctional bronchodilator/anti-inflammatory drugs and bifunctional anti-inflammatory drugs. PMID:24696121

  13. Perovskite-nitrogen-doped carbon nanotube composite as bifunctional catalysts for rechargeable lithium-air batteries.

    PubMed

    Park, Hey Woong; Lee, Dong Un; Park, Moon Gyu; Ahmed, Raihan; Seo, Min Ho; Nazar, Linda F; Chen, Zhongwei

    2015-03-01

    Developing an effective bifunctional catalyst is a significant issue, as rechargeable metal-air batteries are very attractive for future energy systems. In this study, a facile one-pot process is introduced to prepare an advanced bifunctional catalyst (op-LN) incorporating nitrogen-doped carbon nanotubes (NCNTs) into perovskite La0.5 Sr0.5 Co0.8 Fe0.2 O3 nanoparticles (LSCF-NPs). Confirmed by half-cell testing, op-LN exhibits synergistic effects of LSCF-NP and NCNT with excellent bifunctionality for both the oxygen reduction reaction and the oxygen evolution reaction. Furthermore, op-LN exhibits comparable performances in these reactions to Pt/C and Ir/C, respectively, which highlights its potential for use as a commercially viable bifunctional catalyst. Moreover, the results obtained by testing op-LN in a practical Li-air battery demonstrate improved and complementary charge/discharge performance compared to those of LSCF-NP and NCNT, and this confirms that simply prepared op-LN is a promising candidate as a highly effective bifunctional catalyst for rechargeable metal-air batteries. PMID:25684405

  14. Passive Magnetic Bearing

    NASA Technical Reports Server (NTRS)

    Studer, P. A.

    1983-01-01

    Magnetic bearing for limited rotation devices requires no feedback control system to sense and correct shaft position. Passive Magnetic Torsion Bearing requires no power supply and has no rubbing parts. Torsion wire restrains against axial instability. Magnetic flux geometry chosen to assure lateral stability with radial restoring force that maintains alignment.

  15. Bearing servicing tool

    NASA Technical Reports Server (NTRS)

    Boyce, Rex A. (Inventor)

    1992-01-01

    A tool for removing and/or replacing bearings in situ is presented. The tool is comprised of a brace having a first end adapted to engage a first end of the bearing housing, and a second end adapted to engage a second end of the bearing housing. If the two ends of the bearing housing are different in configuration, then the respective ends of the brace are configured accordingly. An elongate guide member integral with the brace has two parts, each projecting endwise from a respective end of the brace. A removable pressure plate can be mounted on either part of the guide member for longitudinal movement therealong and has first and second ends of different configurations adapted to engage the first and second ends of the bearing. A threaded-type drive is cooperative between the guide and the pressure plate to move the pressure plate longitudinally along the guide and apply a force to the bearing, either to remove the bearing from its housing, or to emplace a new bearing in the housing.

  16. Cylindrical bearing analysis

    NASA Technical Reports Server (NTRS)

    Kleckner, R. J.; Pirvics, J.

    1981-01-01

    Program CYBEAN computes behavior of rolling-element bearings including effects of bearing geometry, shaft misalinement, and temperature. Accurate assessment is possible for various outer-ring and housing configurations. CYBEAN is structured for coordinated execution of modules that perform specific analytical tasks. It is written in FORTRAN IV for use on the UNIVAC 1100/40 computer.

  17. 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.

  18. Arcturus and the Bears

    NASA Astrophysics Data System (ADS)

    Antonello, E.

    2009-08-01

    Arcturus is the brightest star in Bootes. The ancient Greek name Arktouros means Bear Guard. The star, however, is not close to Ursa Maior (Big She-Bear) and Ursa Minor (Little She-Bear), as the name would suggest. This curious discrepancy could be explained by the star proper motion, assuming the name Bear Guard is a remote cultural heritage. The proper motion analysis could allow us to get an insight also into an ancient myth regarding Ursa Maior. Though we cannot explain scientifically such a myth, some interesting suggestions can be obtained about its possible origin, in the context of the present knowledge of the importance of the cult of the bear both during the Palaeolithic times and for several primitive populations of modern times, as shown by the ethnological studies.

  19. OTV bearing deflection investigation

    NASA Astrophysics Data System (ADS)

    Reimer, B. L.; Diepenbrock, R. T.; Millis, M. G.

    1993-04-01

    The primary goal of the Bearing Deflectometer Investigation was to gain experience in the use of fiber optic displacement probe technology for bearing health monitoring in a liquid hydrogen turbo pump. The work specified in this Task Order was conducted in conjunction with Air Force Rocket Propulsion Laboratory Contract F04611-86-C-0010. APD conducted the analysis and design coordination to provide a displacement probe design compatible with the XLR-134 liquid hydrogen turbo pump assembly (TPA). Specifications and requirements of the bearing deflectometer were established working with Mechanical Technology Instruments, Inc. (MTI). The TPA design accommodated positioning of the probe to measure outer race cyclic deflections of the pump inlet bearing. The fiber optic sensor was installed as required in the TPA and sensor output was recorded during the TPA testing. Data review indicated that no bearing deflection signature could be differentiated from the inherent system noise. Alternate sensor installations were not investigated, but might yield different results.

  20. 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.

  1. 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.

  2. Enhanced Bifunctional Oxygen Catalysis in Strained LaNiO3 Perovskites.

    PubMed

    Petrie, Jonathan R; Cooper, Valentino R; Freeland, John W; Meyer, Tricia L; Zhang, Zhiyong; Lutterman, Daniel A; Lee, Ho Nyung

    2016-03-01

    Strain is known to greatly influence low-temperature oxygen electrocatalysis on noble metal films, leading to significant enhancements in bifunctional activity essential for fuel cells and metal-air batteries. However, its catalytic impact on transition-metal oxide thin films, such as perovskites, is not widely understood. Here, we epitaxially strain the conducting perovskite LaNiO3 to systematically determine its influence on both the oxygen reduction and oxygen evolution reaction. Uniquely, we found that compressive strain could significantly enhance both reactions, yielding a bifunctional catalyst that surpasses the performance of noble metals such as Pt. We attribute the improved bifunctionality to strain-induced splitting of the eg orbitals, which can customize orbital asymmetry at the surface. Analogous to strain-induced shifts in the d-band center of noble metals relative to the Fermi level, such splitting can dramatically affect catalytic activity in this perovskite and other potentially more active oxides. PMID:26866808

  3. Electrochemical Investigation of Interaction between a Bifunctional Probe and GG Mismatch Duplex.

    PubMed

    Li, Jiao; He, Hanping; Peng, Xiaoqian; Huang, Min; Zhang, Xiuhua; Wang, Shengfu

    2015-01-01

    A bifunctional probe (FecNC), containing a recognition part and an electrochemical active center, was applied to electrochemical detection of GG mismatch duplexes. The preparation of gold electrodes modified by mismatch and complementatry duplexes was characterized by electrochemical impedance spectroscopy (EIS) and optimized for better detection in terms of self-assembly time, hybridization time, and incubation time. The interaction between FecNC and DNA duplexes modified on the surface of a gold electrode was explored by square wave voltammetry (SWV) and EIS. The results showed that the DNA duplexes with GG mismatch on the surface of a gold electrode was easily detected by the largest electrochemical signal of the bifunctional probe because of its selective binding to GG mismatches. The bifunctional probe could offer a simple, effective electrochemical detection of GG mismatches, and theoretical bases for development of electrochemical biosensors. Further, the method would be favorable for diagnosis of genetic diseases. PMID:26165289

  4. Nickel sulfide microsphere film on Ni foam as an efficient bifunctional electrocatalyst for overall water splitting.

    PubMed

    Zhu, Wenxin; Yue, Xiaoyue; Zhang, Wentao; Yu, Shaoxuan; Zhang, Yuhuan; Wang, Jing; Wang, Jianlong

    2016-01-25

    Developing low-cost, efficient, and bifunctional electrocatalysts for both the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) is an appealing yet challenging task. Herein, for the first time, a NiS microsphere film was grown in situ on Ni foam (NiS/Ni foam) via a sulfurization reaction as an efficient bifunctional electrocatalyst for overall water splitting with superior activity and good durability. This NiS/Ni foam electrode delivers 20 mA cm(-2) at an overpotential of 158 mV for the HER and 50 mA cm(-2) at an overpotential of 335 mV for the OER in 1.0 M KOH. This bifunctional electrode also enables a high-efficiency alkaline water electrolyzer with 10 mA cm(-2) at a cell voltage of only 1.64 V, which could be promising in water splitting devices for large-scale hydrogen production. PMID:26661579

  5. Touchdown Ball-Bearing System for Magnetic Bearings

    NASA Technical Reports Server (NTRS)

    Kingsbury, Edward P.; Price, Robert; Gelotte, Erik; Singer, Herbert B.

    2003-01-01

    The torque-limited touchdown bearing system (TLTBS) is a backup mechanical-bearing system for a high-speed rotary machine in which the rotor shaft is supported by magnetic bearings in steady-state normal operation. The TLTBS provides ball-bearing support to augment or supplant the magnetic bearings during startup, shutdown, or failure of the magnetic bearings. The TLTBS also provides support in the presence of conditions (in particular, rotational acceleration) that make it difficult or impossible to control the magnetic bearings or in which the magnetic bearings are not strong enough (e.g., when the side load against the rotor exceeds the available lateral magnetic force).

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

    SciTech Connect

    Shao, Yanqiu; Liu, Heng; Yu, Xiaofang; Guan, Jingqi; Kan, Qiubin

    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.

  7. Magnetically-controlled bearing lubrication

    NASA Technical Reports Server (NTRS)

    Whitaker, A. F.

    1977-01-01

    Proposed magnetic-lubricant ball-bearing assembly has permanently-magnetized bearing retainer fabricated of porous material. Pores of retainer are filled with ferrolubricant. Surface tension causes retainer to deliver sufficient lubricant to nonmagnetic ball bearings.

  8. Evolution of Conifer Diterpene Synthases: Diterpene Resin Acid Biosynthesis in Lodgepole Pine and Jack Pine Involves Monofunctional and Bifunctional Diterpene Synthases1[W][OA

    PubMed Central

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

    2013-01-01

    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

  9. Bifunctional aldehyde/alcohol dehydrogenase (ADHE) in chlorophyte algal mitochondria.

    PubMed

    Atteia, Ariane; van Lis, Robert; Mendoza-Hernández, Guillermo; Henze, Katrin; Martin, William; Riveros-Rosas, Hector; González-Halphen, Diego

    2003-09-01

    Protein profiles of mitochondria isolated from the heterotrophic chlorophyte Polytomella sp. grown on ethanol at pH 6.0 and pH 3.7 were analyzed by Blue Native and denaturing polyacrylamide gel electrophoresis. Steady-state levels of oxidative phosphorylation complexes were influenced by external pH. Levels of an abundant, soluble, mitochondrial protein of 85 kDa and its corresponding mRNA increased at pH 6.0 relative to pH 3.7. N-terminal and internal sequencing of the 85 kDa mitochondrial protein together with the corresponding cDNA identified it as a bifunctional aldehyde/alcohol dehydrogenase (ADHE) with strong similarity to homologues from eubacteria and amitochondriate protists. A mitochondrial targeting sequence of 27 amino acids precedes the N-terminus of the mature mitochondrial protein. A gene encoding an ADHE homologue was also identified in the genome of Chlamydomonas reinhardtii, a photosynthetic relative of Polytomella. ADHE reveals a complex picture of sequence similarity among homologues. The lack of ADHE from archaebacteria indicates a eubacterial origin for the eukaryotic enzyme. Among eukaryotes, ADHE has hitherto been characteristic of anaerobes since it is essential to cytosolic energy metabolism of amitochondriate protists such as Giardia intestinalis and Entamoeba histolytica. Its abundance and expression pattern suggest an important role for ADHE in mitochondrial metabolism of Polytomella under the conditions studied. The current data are compatible with the view that Polytomella ADHE could be involved either in ethanol production or assimilation, or both, depending upon environmental conditions. Presence of ADHE in an oxygen-respiring algal mitochondrion and co-expression at ambient oxygen levels with respiratory chain components is unexpected with respect to the view that eukaryotes acquired ADHE genes specifically as an adaptation to an anaerobic lifestyle. PMID:14756315

  10. Physical properties of bifunctional BST/LSMO nanocomposites

    SciTech Connect

    Beltran-Huarac, Juan Morell, Gerardo; Martinez, Ricardo

    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.

  11. 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

  12. Structural basis for bifunctional peptide recognition at human δ-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 μ- and δ-opioid receptor (OR) ligands are potential therapeutic alternatives, with diminished side effects, to alkaloid opiate analgesics. We solved the structure of human δ-OR bound to the bifunctional δ-OR antagonist and μ-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

  13. Structural basis for bifunctional peptide recognition at human δ-opioid receptor

    DOE PAGESBeta

    Fenalti, Gustavo; Zatsepin, Nadia A.; Betti, Cecilia; Giguere, Patrick; Han, Gye Won; Ishchenko, Andrii; Liu, Wei; Guillemyn, Karel; Zhang, Haitao; James, Daniel; et al

    2015-02-16

    Bi-functional μ- and δ- opioid receptor (OR) ligands are potential therapeutic alternatives to alkaloid opiate analgesics with diminished side effects. We solved the structure of human δ-OR bound to the bi-functional δ-OR antagonist and μ-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. In summary, the observed receptor-peptide interactions are critical to understand the pharmacological profiles of opioid peptides, and to develop improved analgesics.

  14. Structural basis for bifunctional peptide recognition at human δ-opioid receptor

    SciTech Connect

    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

    2015-02-16

    Bi-functional μ- and δ- opioid receptor (OR) ligands are potential therapeutic alternatives to alkaloid opiate analgesics with diminished side effects. We solved the structure of human δ-OR bound to the bi-functional δ-OR antagonist and μ-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. In summary, the observed receptor-peptide interactions are critical to understand the pharmacological profiles of opioid peptides, and to develop improved analgesics.

  15. 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.

  16. Magnetic bearing update

    SciTech Connect

    Fowler, T.K.

    1995-05-25

    Stabilization of whirl instability by floppy, viscous bearing mounts is discussed and required material properties are estimated for the new tilt-whirl mode in eddy-current stabilized magnetic bearings. A relatively low Young`s modules Y {approximately} 10{sup 5} and high viscosity {zeta} {approximately} 10{sup 7} are required (both in MKS units), suggesting the need for careful mounting design. New information on periodic bearings shows that, thus far, Earshaw`s Theorem cannot be defeated by periodicity, despite the author`s earlier claims.

  17. Ball and Roller Bearings. A Teaching Reference.

    ERIC Educational Resources Information Center

    American Association for Vocational Instructional Materials, Athens, GA.

    The manual provides a subject reference for ball and roller bearings. The following topics are included: (1) bearing nomenclature, (2) bearing uses, (3) bearing capacities, (4) shop area working conditions, (5) bearing removal, (6) bearing cleaning and inspection, (7) bearing replacement, (8) bearing lubrication, (9) bearing installation, (10)…

  18. Arkansas black bear hunter survey

    USGS Publications Warehouse

    Pharris, Larry D.; Clark, Joseph D.

    1987-01-01

    Questionnaires were mailed to black bear (Ursus americanus) hunters in Arkansas following the 1980-84 bear seasons to determine participation, hunter success, and number of bears observed by hunters. Man-days of hunting to harvest a bear ranged from 148 to 671 and hunter success ranged from 0.4% to 2.2%. With the exception of 1980, number of permits issued, man-days of bear hunting, and bears harvested appear affected by hunting permit cost. 

  19. Local Attitudes towards Bear Management after Illegal Feeding and Problem Bear Activity.

    PubMed

    Dubois, Sara; Fraser, David

    2013-01-01

    The "pot bears" received international media attention in 2010 after police discovered the intentional feeding of over 20 black bears during the investigation of an alleged marijuana-growing operation in Christina Lake, British Columbia, Canada. A two-phase random digit dialing survey of the community was conducted in 2011 to understand local perspectives on bear policy and management, before and after a summer of problem bear activity and government interventions. Of the 159 households surveyed in February 2011, most had neutral or positive attitudes towards bears in general, and supported the initial decision to feed the food-conditioned bears until the autumn hibernation. In contrast to wildlife experts however, most participants supported relocating the problem bears, or allowing them to remain in the area, ahead of killing; in part this arose from notions of fairness despite the acknowledged problems of relocation. Most locals were aware of the years of feeding but did not report it, evidently failing to see it as a serious form of harm, even after many bears had been killed. This underscores the importance of preventive action on wildlife feeding and the need to narrow the gap between public and expert opinion on the likely effects of relocation versus killing. PMID:26479542

  20. Rice bifunctional phytocystatin is a dual modulator of legumain and papain-like proteases.

    PubMed

    Christoff, Ana Paula; Passaia, Gisele; Salvati, Caroline; Alves-Ferreira, Márcio; Margis-Pinheiro, Marcia; Margis, Rogerio

    2016-09-01

    Phytocystatins are well-known inhibitors of C1A cysteine proteinases. However, previous research has revealed legumain (C13) protease inhibition via a carboxy-extended phytocystatin. Among the 12 phytocystatins genes in rice, OcXII is the only gene possessing this carboxy-terminal extension. The specific legumain inhibition activity was confirmed, in our work, using a recombinant OcXII harboring only the carboxy-terminal domain and this part did not exhibit any effect on papain-like activities. Meanwhile, rice plants silenced at the whole OcXII gene presented higher legumain and papain-like proteolytic activities, resulting in a faster initial seedling growth. However, when germinated under stressful alkaline conditions, OcXII-silenced plants exhibited impaired root formation and delayed shoot growth. Interestingly, the activity of OcXII promoter gene was detected in the rice seed scutellum region, and decreases with seedling growth. Seeds from these plants also exhibited slower growth at germination under ABA or alkaline conditions, while maintaining very high levels of OcXII transcriptional activation. This likely reinforces the proteolytic control necessary for seed germination and growth. In addition, increased legumain activity was detected in OcXII RNAi plants subjected to a fungal elicitor. Overall, the results of this study highlight the association of OcXII with not only plant development processes, but also with stress response pathways. The results of this study reinforce the bifunctional ability of carboxy-extended phytocystatins in regulating legumain proteases via its carboxy-extended domain and papain-like proteases by its amino-terminal domain. PMID:27325119

  1. Characterization and expression of human bifunctional 3'-phosphoadenosine 5'-phosphosulphate synthase isoforms.

    PubMed Central

    Fuda, Hirotoshi; Shimizu, Chikara; Lee, Young C; Akita, Harukuni; Strott, Charles A

    2002-01-01

    Sulphonation, a fundamental process essential for normal growth and development, requires the sulphonate donor molecule 3'-phosphoadenosine 5'-phosphosulphate (PAPS), which is produced from ATP and inorganic sulphate by the bifunctional enzyme PAPS synthase. In humans, two genes encode isoenzymes that are 77% identical at the amino acid level, and alternative splicing creates two subtypes of PAPS synthase 2. The question as to whether distinctions in amino acid composition are reflected in differences in activity has been examined. The specific activity of the PAPS synthase 2 subtypes is 10- to 15-fold higher than that for PAPS synthase 1. The greater catalytic efficiency of the PAPS synthase 2 subtypes is demonstrated further by the 3- to 6-fold higher k(cat)/K(m) ratios for ATP and inorganic sulphate as compared with the ratios for PAPS synthase 1. In humans, PAPS synthase 1 is expressed ubiquitously, and is the dominant isoform in most tissues, whereas expression of the PAPS synthase 2 subtypes is variable and tissue-specific. It is noteworthy that, similar to other human tissues, PAPS synthase 1 also appears to be the dominant isoform expressed in cartilage. The latter finding initially created a conundrum, since there is a specific human dwarfing disorder that is known to be caused by a mutation in the PAPS synthase 2 gene. This apparent enigma would seem to be resolved by examination of cartilage from guinea-pigs as an animal model. Similar to humans, cartilage from mature animals predominantly expresses PAPS synthase 1. In contrast, expression of PAPS synthase 1 is relatively low in the cartilage of immature guinea-pigs, including the growth plate of long bones, whereas PAPS synthase 2 is the highly expressed isoenzyme. PMID:11931637

  2. Roller bearing geometry design

    NASA Technical Reports Server (NTRS)

    Savage, M.; Pinkston, B. H. W.

    1976-01-01

    A theory of kinematic stabilization of rolling cylinders is extended and applied to the design of cylindrical roller bearings. The kinematic stabilization mechanism puts a reverse skew into the rolling elements by changing the roller taper. Twelve basic bearing modification designs are identified amd modeled. Four have single transverse convex curvature in their rollers while eight have rollers which have compound transverse curvature made up of a central cylindrical band surrounded by symmetric bands with slope and transverse curvature. The bearing designs are modeled for restoring torque per unit axial displacement, contact stress capacity, and contact area including dynamic loading, misalignment sensitivity and roller proportion. Design programs are available which size the single transverse curvature roller designs for a series of roller slopes and load separations and which design the compound roller bearings for a series of slopes and transverse radii of curvature. The compound rollers are proportioned to have equal contact stresses and minimum size. Design examples are also given.

  3. Magnetically levitated superconducting bearing

    SciTech Connect

    Weinberger, B.R.; Lynds, L. Jr.

    1993-10-26

    A magnetically levitated superconducting bearing includes a magnet mounted on a shaft that is rotatable around an axis of rotation and a Type II superconductor supported on a stator in proximity to the magnet. The superconductor is positioned so that when it is cooled to its superconducting state in the presence of a magnetic field, it interacts with the magnet to produce an attractive force that levitates the magnet and supports a load on the shaft. The interaction between the superconductor and magnet also produces surface screening currents that generate a repulsive force perpendicular to the load. The bearing also has means for maintaining the superconductor at a temperature below its critical temperature. The bearing could also be constructed so the magnet is supported on the stator and the superconductor is mounted on the shaft. The bearing can be operated by cooling the superconductor to its superconducting state in the presence of a magnetic field. 6 figures.

  4. Hydrostatic bearing support

    NASA Technical Reports Server (NTRS)

    Cunningham, R. E. (Inventor)

    1977-01-01

    A hydrostatic bearing support system is provided which comprises a bearing housing having a polygonally configured outer surface which defines at least three symmetrically disposed working faces and a plurality of pressure plates, each of which is disposed relatively opposite a corresponding working face and spaced therefrom to define a gap therebetween. A hydrostatic support film is created in the gap for supporting the housing in spaced relationship to the pressure plates.

  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. Deformable bearing seat

    NASA Technical Reports Server (NTRS)

    Moreman, O. S., III (Inventor)

    1977-01-01

    A deformable bearing seat is described for seating a bearing assembly in a housing. The seat includes a seating surface in the housing having a first predetermined spheroidal contour when the housing is in an undeformed mode. The seating surface is deformable to a second predetermined spherically contoured surface when the housing is in a deformed mode. The seat is particularly adaptable for application to a rotating blade and mounting ring assembly in a gas turbine engine.

  7. Load responsive hydrodynamic bearing

    DOEpatents

    Kalsi, Manmohan S.; Somogyi, Dezso; Dietle, Lannie L.

    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.

  8. Magnetic bearing and motor

    NASA Technical Reports Server (NTRS)

    Studer, P. A. (Inventor)

    1983-01-01

    A magnetic bearing for passively suspending a rotatable element subjected to axial and radial thrust forces is disclosed. The magnetic bearing employs a taut wire stretched along the longitudinal axis of the bearing between opposed end pieces and an intermediate magnetic section. The intermediate section is segmented to provide oppositely directed magnetic flux paths between the end pieces and may include either an axially polarized magnets interposed between the segments. The end pieces, separated from the intermediate section by air gaps, control distribution of magnetic flux between the intermediate section segments. Coaxial alignment of the end pieces with the intermediate section minimizes magnetic reluctance in the flux paths endowing the bearing with self-centering characteristics when subjected to radial loads. In an alternative embodiment, pairs of oppositely wound armature coils are concentrically interposed between segments of the intermediate section in concentric arcs adjacent to radially polarized magnets to equip a magnetic bearing as a torsion drive motor. The magnetic suspension bearing disclosed provides long term reliability without maintenance with application to long term space missions such as the VISSR/VAS scanning mirror instrument in the GOES program.

  9. 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.

  10. 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.

  11. Evaluation of SRM flex bearing materials and processes

    NASA Technical Reports Server (NTRS)

    Wood, T. E.

    1980-01-01

    Tensile, peel, and shear testing was performed on combinations of primers, adhesives, tycements and rubber compounds cured at various times and temperatures. The materials used in the fabrication of the solid rocket motor flex bearing as well as in other systems were evaluated. A compatibility study between adhesives and tycements was initiated. The flex bearing mold design was reviewed by our tooling experts.

  12. Exploiting metal-ligand bifunctional reactions in the design of iron asymmetric hydrogenation catalysts.

    PubMed

    Morris, Robert H

    2015-05-19

    This is an Account of our development of iron-based catalysts for the asymmetric transfer hydrogenation (ATH) and asymmetric pressure hydrogenation (AH) of ketones and imines. These chemical processes provide enantiopure alcohols and amines for use in the pharmaceutical, agrochemical, fragrance, and other fine chemical industries. Fundamental principles of bifunctional reactivity obtained by studies of ruthenium catalysts by Noyori's group and our own with tetradentate ligands with tertiary phosphine and secondary amine donor groups were applied to improve the performance of these first iron(II) catalysts. In particular the correct positioning of a bifunctional H-Fe-NH unit in an iron hydride amine complex leads to exceptional catalyst activity because of the low energy barrier of dihydrogen transfer to the polar bond of the substrate. In addition the ligand structure with this NH group along with an asymmetric array of aryl groups orients the incoming substrate by hydrogen-bonding, and steric interactions provide the hydrogenated product in high enantioselectivity for several classes of substrates. Enantiomerically pure diamines or diphenylphosphino-amine compounds are used as the source of the asymmetry in the tetradentate ligands formed by the condensation of the amines with dialkyl- or diaryl-phosphinoaldehydes, a synthesis that is templated by Fe(II). The commercially available ortho-diphenylphosphinobenzaldehyde was used in the initial studies, but then diaryl-phosphinoacetaldehydes were found to produce much more effective ligands for iron(II). Once the mechanism of catalysis became clearer, the iron-templated synthesis of (S,S)-PAr2CH2CH2NHCHPhCHPhNH2 ligand precursors was developed to specifically introduce a secondary amine in the precatalyst structures. The reaction of a precatalyst with strong base yields a key iron-amido complex that reacts with isopropanol (in ATH) or dihydrogen (in AH) to generate an iron hydride with the Fe-H bond parallel to the

  13. Local Attitudes towards Bear Management after Illegal Feeding and Problem Bear Activity

    PubMed Central

    Dubois, Sara; Fraser, David

    2013-01-01

    Simple Summary The “pot bears” received international media attention in 2010 after police discovered the intentional feeding of black bears during the investigation of an alleged marijuana-growing operation in Christina Lake, British Columbia. Residents of this small community were surveyed by phone twice over the following year, before and after government actions. This study aimed to understand local attitudes on how these bears should be managed and whether they differed from existing bear management policy. Results indicate a significant problem with the public view of wildlife feeding and a gap between public and expert opinion on relocation and killing of food-conditioned wildlife. Abstract The “pot bears” received international media attention in 2010 after police discovered the intentional feeding of over 20 black bears during the investigation of an alleged marijuana-growing operation in Christina Lake, British Columbia, Canada. A two-phase random digit dialing survey of the community was conducted in 2011 to understand local perspectives on bear policy and management, before and after a summer of problem bear activity and government interventions. Of the 159 households surveyed in February 2011, most had neutral or positive attitudes towards bears in general, and supported the initial decision to feed the food-conditioned bears until the autumn hibernation. In contrast to wildlife experts however, most participants supported relocating the problem bears, or allowing them to remain in the area, ahead of killing; in part this arose from notions of fairness despite the acknowledged problems of relocation. Most locals were aware of the years of feeding but did not report it, evidently failing to see it as a serious form of harm, even after many bears had been killed. This underscores the importance of preventive action on wildlife feeding and the need to narrow the gap between public and expert opinion on the likely effects of relocation versus

  14. 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

  15. Porous MoO2 Nanosheets as Non-noble Bifunctional Electrocatalysts for Overall Water Splitting.

    PubMed

    Jin, Yanshuo; Wang, Haotian; Li, Junjie; Yue, Xin; Han, Yujie; Shen, Pei Kang; Cui, Yi

    2016-05-01

    A porous MoO2 nanosheet as an active and stable bifunctional electrocatalyst for overall water splitting, is presented. It needs a cell voltage of only about 1.53 V to achieve a current density of 10 mA cm(-2) and maintains its activity for at least 24 h in a two-electrode configuration. PMID:26996884

  16. Sensitivity and robustness in covalent modification cycles with a bifunctional converter enzyme.

    PubMed

    Straube, Ronny

    2013-10-15

    Regulation by covalent modification is a common mechanism to transmit signals in biological systems. The modifying reactions are catalyzed either by two distinct converter enzymes or by a single bifunctional enzyme (which may employ either one or two catalytic sites for its opposing activities). The reason for this diversification is unclear, but contemporary theoretical models predict that systems with distinct converter enzymes can exhibit enhanced sensitivity to input signals whereas bifunctional enzymes with two catalytic sites are believed to generate robustness against variations in system's components. However, experiments indicate that bifunctional enzymes can also exhibit enhanced sensitivity due to the zero-order effect, raising the question whether both phenomena could be understood within a common mechanistic model. Here, I argue that this is, indeed, the case. Specifically, I show that bifunctional enzymes with two catalytic sites can exhibit both ultrasensitivity and concentration robustness, depending on the kinetic operating regime of the enzyme's opposing activities. The model predictions are discussed in the context of experimental observations of ultrasensitivity and concentration robustness in the uridylylation cycle of the PII protein, and in the phosphorylation cycle of the isocitrate dehydrogenase, respectively. PMID:24138868

  17. Asymmetric α-amination of β-keto esters using a guanidine–bisurea bifunctional organocatalyst

    PubMed Central

    Yamamoto, Yoshiharu

    2016-01-01

    Summary An asymmetric α-amination of β-keto esters with azodicarboxylate in the presence of a guanidine–bisurea bifunctional organocatalyst was investigated. The α-amination products were obtained in up to 99% yield with up to 94% ee. PMID:26977179

  18. Bifunctional N-heterocyclic carbene-catalyzed highly enantioselective synthesis of spirocyclic oxindolo-β-lactams.

    PubMed

    Zhang, Han-Ming; Gao, Zhong-Hua; Ye, Song

    2014-06-01

    The N-heterocyclic carbene-catalyzed Staudinger reaction of ketenes with isatin-derived ketimines was investigated. The bifunctional NHCs with a free hydroxyl group were demonstrated as efficient catalysts for the reaction, giving the corresponding spirocyclic oxindolo-β-lactams in high yields with excellent diastereo- and enantioselectivities. PMID:24856000

  19. 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.

  20. Climate Drives Polar Bear Origins

    Technology Transfer Automated Retrieval System (TEKTRAN)

    In their provocative analysis of northern bears (“Nuclear genomic sequences reveal that polar bears are an old and distinct bear lineage,” Reports, 20 April, p. 344), F. Hailer et al. use independent nuclear loci to show that polar bears originated during the middle Pleistocene, rather than during t...

  1. Magnetic Bearing Consumes Low Power

    NASA Technical Reports Server (NTRS)

    Studer, P. A.

    1982-01-01

    Energy-efficient linear magnetic bearing maintains a precise small separation between its moving and stationary parts. Originally designed for cryogenic compressors on spacecraft, proposed magnetic bearing offers an alternative to roller or gas bearing in linear motion system. Linear noncontacting bearing operates in environments where lubricants cannot be used.

  2. Synthesis of hetero-polymer functionalized nanocarriers by combining surface-initiated ATRP and RAFT polymerization.

    PubMed

    Huang, Xin; Hauptmann, Nicole; Appelhans, Dietmar; Formanek, Petr; Frank, Simon; Kaskel, Stefan; Temme, Achim; Voit, Brigitte

    2012-12-01

    Smart nanocarriers are created based on a bi-functional hetero-initiator for RAFT and ATRP technique, bi-functionalizing mesoporous silica nanoparticles with two polymer types. The pH-dependent behavior of PDEAEMA as the gatekeeper polymer is verified by electrokinetic measurements and a controlled release behavior is demonstrated using doxorubicin as the drug. PMID:22911545

  3. Bifunctional combined Au-Fe(2)O(3) nanoparticles for induction of cancer cell-specific apoptosis and real-time imaging.

    PubMed

    Gao, Wen; Ji, Lifei; Li, Lu; Cui, Guanwei; Xu, Kehua; Li, Ping; Tang, Bo

    2012-05-01

    We demonstrate bifunctional combined Au-Fe(2)O(3) nanoparticles (NPs) for selectively induction of apoptosis in cancer cells and real-time imaging. The as-prepared Au-Fe(2)O(3) NPs combine the merits of both Au and γ-Fe(2)O(3) NPs, maintaining excellent fluorescence quenching property and catalytic activity. Conjugated with α(Ⅴ)β(3) integrin-targeting peptide (RGD) and fluorescein isothiocyanate (FITC)-labeled capsase-3 recognition sequence (DEVD) on the Au surface, the resulting RGD/FITC-DEVD-Au-Fe(2)O(3) NPs bind preferentially to integrin α(Ⅴ)β(3)-rich human liver cancer cells (HepG2), sequentially initiate catalytic formation of hydroxyl radicals (·OH) and enable the real-time monitoring of·OH-induced caspase-3-dependent apoptosis in these cancer cells. Furthermore, the catalytic activity of RGD/FITC-DEVD-Au-Fe(2)O(3) NPs is much higher than that of individual γ-Fe(2)O(3) NPs due to the polarization effect at the Au-Fe(2)O(3) interface. Such bifunctional Au-Fe(2)O(3) NPs exhibit simultaneous targeting, therapeutic and imaging functions and are therefore promising for future therapeutic applications in cancer. PMID:22342711

  4. Hydrothermal synthesis of superparamagnetic and red luminescent bifunctional Fe3O4@Mn2+-doped NaYF4:Yb/Er core@shell monodisperse nanoparticles and their subsequent ligand exchange in water

    NASA Astrophysics Data System (ADS)

    Qin, Zhenli; Du, Sinan; Luo, Yang; Liao, Zhijian; Zuo, Fang; Luo, Jianbin; Liu, Dong

    2016-08-01

    We report the use of an efficient hydrothermal method to synthesize superparamagnetic and red luminescent bifunctional Fe3O4@Mn2+-doped NaYF4:Yb/Er nanoparticles (NPs) with core@shell structures via a seed-growth procedure. Oleic acid coated Fe3O4 (OA-Fe3O4) NPs were initially synthesized using a coprecipitation method. The as-synthesized OA-Fe3O4 NPs were then used as seeds, on which the red upconversion luminescent shell (Mn2+-doped NaYF4:Yb/Er) was formed. Furthermore, hydrophobic to hydrophilic surface modification of the Fe3O4@Mn2+-doped NaYF4:Yb/Er NPs was achieved via a ligand exchange method where oleic acid was displaced by a PEG phosphate ligand [PEG = poly(ethylene glycol)]. These materials were characterized by means of transmission electron microscopy (TEM), X-ray diffraction (XRD), photoluminescence (PL) spectroscopy, and vibrating sample magnetometry (VSM). The Fe3O4 cores were uniformly coated with a Mn2+-doped NaYF4:Yb/Er shell, and the bifunctional Fe3O4@Mn2+-doped NaYF4:Yb/Er NPs were monodispersed. Furthermore, the Fe3O4@Mn2+-doped NaYF4:Yb/Er NPs exhibited a saturated magnetization value of 6.2 emu/g and emitted red luminescence under a 980 nm laser. The obtained bifunctional Fe3O4@Mn2+-doped NaYF4:Yb/Er NPs may find potential applications in drug targeting, bioseparation, and diagnostic analysis. The synthetic method may be employed for the preparation of other bifunctional nanomaterials.

  5. Fluid lubricated bearing assembly

    DOEpatents

    Boorse, Henry A.; Boeker, Gilbert F.; Menke, John R.

    1976-01-01

    1. A support for a loaded rotatable shaft comprising in combination on a housing having a fluid-tight cavity encasing an end portion of said shaft, a thrust bearing near the open end of said cavity for supporting the axial thrust of said shaft, said thrust bearing comprising a thrust plate mounted in said housing and a thrust collar mounted on said shaft, said thrust plate having a central opening the peripheral portion of which is hermetically sealed to said housing at the open end of said cavity, and means for supplying a fluid lubricant to said thrust bearing, said thrust bearing having a lubricant-conducting path connecting said lubricant supplying means with the space between said thrust plate and collar intermediate the peripheries thereof, the surfaces of said plate and collar being constructed and arranged to inhibit radial flow of lubricant and, on rotation of said thrust collar, to draw lubricant through said path between the bearing surfaces and to increase the pressure therebetween and in said cavity and thereby exert a supporting force on said end portion of said shaft.

  6. Solving bearing overheating problems

    SciTech Connect

    Jendzurski, T.

    1995-05-08

    Overheating is a major indicator, along with vibration and noise, of an underlying problem affecting a bearing or related components. Because normal operating temperatures vary widely from one application to another, no single temperature is a reliable sign of overheating in every situation. By observing an application when it is running smoothly, a technician can establish a benchmark temperature for a particular bearing arrangement. Wide deviations from this accepted norm generally indicate troublesome overheating. The list of possible causes of over-heating ranges from out-of-round housings and oversize shaft diameters to excessive lubrication and bearing preloading. These causes fall into two major categories: improper or faulty lubrication and mechanical problems, such as incorrect fits and tolerances. These are discussed along with solutions.

  7. 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

  8. Magnetic bearings for spacecraft

    NASA Technical Reports Server (NTRS)

    Studer, P. A.

    1972-01-01

    Magnetic bearings have been successfully applied to motorized rotor systems in the multi-kilogram range, at speeds up to 1200 radians per second. These engineering models also indicated the need for continued development in specific areas to make them feasible for spacecraft applications. Significant power reductions have recently been attained. A unique magnetic circuit, combining permanent magnets with electromagnetic control, has a bidirectional forcing capability with improved current sensitivity. The multi-dimensional nature of contact-free rotor support is discussed. Stable continuous radial suspension is provided by a rotationally symmetric permanent magnet circuit. Two bearings, on a common shaft, counteract the normal instability perpendicular to the rotational axis. The axial direction is servoed to prevent contact. A new bearing technology and a new field of application for magnetics is foreseen.

  9. 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.

  10. Organocatalytic Domino Oxa-Michael/1,6-Addition Reactions: Asymmetric Synthesis of Chromans Bearing Oxindole Scaffolds.

    PubMed

    Zhao, Kun; Zhi, Ying; Shu, Tao; Valkonen, Arto; Rissanen, Kari; Enders, Dieter

    2016-09-19

    An asymmetric organocatalytic domino oxa-Michael/1,6-addition reaction of ortho-hydroxyphenyl-substituted para-quinone methides and isatin-derived enoates has been developed. In the presence of 5 mol % of a bifunctional thiourea organocatalyst, this scalable domino reaction affords 4-phenyl-substituted chromans bearing spiro-connected oxindole scaffolds and three adjacent stereogenic centers in good to excellent yields (up to 98 %) and with very high stereoselectivities (up to >20:1 d.r., >99 % ee). PMID:27600477

  11. 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.

  12. 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.

  13. Modular gear bearings

    NASA Technical Reports Server (NTRS)

    Vranish, John M. (Inventor)

    2009-01-01

    A gearing system using modular gear bearing components. Each component is composed of a core, one or more modules attached to the core and two or more fastening modules rigidly attaching the modules to the core. The modules, which are attached to the core, may consist of gears, rollers or gear bearing components. The core orientation affects the orientation of the modules attached to the core. This is achieved via the keying arrangement of the core and the component modules that attach to the core. Such an arrangement will also facilitate the phase tuning of gear modules with respect to the core and other gear modules attached to the core.

  14. 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.

  15. Hybrid superconductor magnet bearings

    SciTech Connect

    Chu, W.

    1995-04-01

    Hybrid superconductor magnet bearings (HSMB`s) utilize high temperature superconductors (HTS`s) together with permanent magnets to form a frictionless interface between relatively rotating parts. They are low mass, stable, and do not incur expenditure of energy during normal operation. There is no direct physical contact between rotor and stator, and hence there is no wear and tear. However, just as any other applications of HTS`s, it requires a very cold temperature to function. Whereas this might be perceived as a disadvantage on earth, it is of no great concern in space or on the moon. To astronomers, the moon is an excellent site for an observatory, but the cold and dusty vacuum environment on the moon precludes the use of mechanical bearings on the telescope mounts. Furthermore, drive mechanisms with very fine steps, and hence bearings with extremely low friction are needed to track a star from the moon, because the moon rotates very slowly. All aspects considered, the HSMB is about the only candidate that fits in naturally. Here, the authors present a design for one such bearing, capable of supporting a telescope that weighs about 3 lbs on Earth.

  16. Hybrid superconductor magnet bearings

    NASA Astrophysics Data System (ADS)

    Chu, Wei-Kan

    1995-04-01

    Hybrid superconductor magnet bearings (HSMB's) utilize high temperature superconductors (HTS's) together with permanent magnets to form a frictionless interface between relatively rotating parts. They are low mass, stable, and do not incur expenditure of energy during normal operation. There is no direct physical contact between rotor and stator, and hence there is no wear and tear. However, just as any other applications of HTS's, it requires a very cold temperature to function. Whereas this might be perceived as a disadvantage on earth, it is of no great concern in space or on the moon. To astronomers, the moon is an excellent site for an observatory, but the cold and dusty vacuum environment on the moon precludes the use of mechanical bearings on the telescope mounts. Furthermore, drive mechanisms with very fine steps, and hence bearings with extremely low friction are needed to track a star from the moon, because the moon rotates very slowly. All aspects considered, the HSMB is about the only candidate that fits in naturally. Here, we present a design for one such bearing, capable of supporting a telescope that weighs about 3 lbs on Earth.

  17. 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.

  18. The Teddy Bears' Disc.

    ERIC Educational Resources Information Center

    Laurillard, Diana

    1985-01-01

    Reports an evaluation of the Teddy Bear disc, an interactive videodisc developed at the Open University for a second-level course in metallurgy and materials technology. Findings from observation of students utilizing the videodisc are reviewed; successful design features and design problems are considered; and development costs are outlined. (MBR)

  19. Hybrid superconductor magnet bearings

    NASA Technical Reports Server (NTRS)

    Chu, Wei-Kan

    1995-01-01

    Hybrid superconductor magnet bearings (HSMB's) utilize high temperature superconductors (HTS's) together with permanent magnets to form a frictionless interface between relatively rotating parts. They are low mass, stable, and do not incur expenditure of energy during normal operation. There is no direct physical contact between rotor and stator, and hence there is no wear and tear. However, just as any other applications of HTS's, it requires a very cold temperature to function. Whereas this might be perceived as a disadvantage on earth, it is of no great concern in space or on the moon. To astronomers, the moon is an excellent site for an observatory, but the cold and dusty vacuum environment on the moon precludes the use of mechanical bearings on the telescope mounts. Furthermore, drive mechanisms with very fine steps, and hence bearings with extremely low friction are needed to track a star from the moon, because the moon rotates very slowly. All aspects considered, the HSMB is about the only candidate that fits in naturally. Here, we present a design for one such bearing, capable of supporting a telescope that weighs about 3 lbs on Earth.

  20. Composite Bear Canister

    NASA Technical Reports Server (NTRS)

    Chung, W. Richard; Jara, Steve; Suffel, Susan

    2003-01-01

    To many national park campers and mountain climbers saving their foods in a safe and unbreakable storage container without worrying being attacked by a bear is a challenging task. In some parks, the park rangers have mandated that park visitors rent a bear canister for their food storage. Commercially available bear canisters are made of ABS plastic, weigh 2.8 pounds, and have a 180 cubic inch capacity for food storage. A new design with similar capacity was conducted in this study to reduce its weight and make it a stiffer and stronger canister. Two prototypes incorporating carbon prepreg with and without honeycomb constructions were manufactured using hand lay-up and vacuum bag forming techniques. A 6061-T6-aluminum ring was machined to dimensions in order to reinforce the opening area of the canister. Physical properties (weight and volume) along with mechanical properties (flexural strength and specific allowable moment) of the newly fabricated canisters are compared against the commercial ones. The composite canister weighs only 56% of the ABS one can withstand 9 times of the force greater. The advantages and limitations of using composite bear canisters will be discussed in the presentation.

  1. 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˜rα, with an optimal exponent α=α× 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.

  2. Magnetically leviated superconducting bearing

    DOEpatents

    Weinberger, Bernard R.; Lynds, Jr., Lahmer

    1993-01-01

    A magnetically levitated superconducting bearing includes a magnet (2) mounted on a shaft (12) that is rotatable around an axis of rotation and a Type II superconductor (6) supported on a stator (14) in proximity to the magnet (2). The superconductor (6) is positioned so that when it is cooled to its superconducting state in the presence of a magnetic field, it interacts with the magnet (2) to produce an attractive force that levitates the magnet (2) and supports a load on the shaft (12). The interaction between the superconductor (6) and magnet(2) also produces surface screening currents (8) that generate a repulsive force perpendicular to the load. The bearing also has means for maintaining the superconductor at a temperature below its critical temperature (16, 18). The bearing could also be constructed so the magnet (2) is supported on the stator (14) and the superconductor (6) is mounted on the shaft (12). The bearing can be operated by cooling the superconductor (6) to its superconducting state in the presence of a magnetic field.

  3. Lubricant effects on bearing life

    NASA Technical Reports Server (NTRS)

    Zaretsky, Erwin V.

    1986-01-01

    Lubricant considerations for rolling-element bearings have within the last two decades taken on added importance in the design and operation of mechanical systems. The phenomenon which limits the useful life of bearings is rolling-element or surface pitting fatigue. The elastohydrodynamic (EHD) film thickness which separates the ball or roller surface from those of the raceways of the bearing directly affects bearing life. Chemical additives added to the lubricant can also significantly affect bearings life and reliability. The interaction of these physical and chemical effects is important to the design engineer and user of these systems. Design methods and lubricant selection for rolling-element bearings are presented and discussed.

  4. Magnetic-Bearing Test Fixture

    NASA Technical Reports Server (NTRS)

    Groom, Nelson J.; Poole, William L.

    1991-01-01

    Microcomputer-controlled magnetic-bearing test fixture used to develop approaches to design of controls for magnetic bearing actuators designed and constructed. Includes load cells connected to bar, in turn, connected through screw positioners to geared drive motors. Position of equivalent suspended element sensed by position sensors and controlled by drive motors. Provides control of gap in magnetic bearing and of current in electromagnet coil. Measurements made include magnetic-bearing gaps, magnetic flux in bearing gaps, and bearing forces. Approaches to linearization and control developed by use of fixture applicable to wide range of small-gap suspension systems.

  5. Flexure Bearing Reduces Startup Friction

    NASA Technical Reports Server (NTRS)

    Clingman, W. Dean

    1991-01-01

    Design concept for ball bearing incorporates small pieces of shim stock, wire spokes like those in bicycle wheels, or other flexing elements to reduce both stiction and friction slope. In flexure bearing, flexing elements placed between outer race of ball bearing and outer ring. Elements flex when ball bearings encounter small frictional-torque "bumps" or even larger ones when bearing balls encounter buildups of grease on inner or outer race. Flexure of elements reduce high friction slopes of "bumps", helping to keep torque between outer ring and inner race low and more nearly constant. Concept intended for bearings in gimbals on laser and/or antenna mirrors.

  6. 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.

  7. Modular "Click" Preparation of Bifunctional Polymeric Heterometallic Catalysts.

    PubMed

    Wang, Wenlong; Zhao, Liyuan; Lv, Hui; Zhang, Guodong; Xia, Chungu; Hahn, F Ekkehardt; Li, Fuwei

    2016-06-27

    Heterobimetallic molecular complexes or strictly alternating metallated polymers are obtained by a click reaction between mononuclear metal complexes (secondary building units, SBUs) bearing NHCs functionalized with either p-azidophenyl or p-ethynylphenyl wingtips. With a copper-NHC complex as SBU the formation of molecular or polymeric compounds did not require any additives as the copper complex catalyzes the click reaction. Transmetallation from heterobimetallic Cu/Ag derivatives to Cu/Pd derivatives was achieved. The linker between the SBUs (flexible or rigid) influences the catalytic activity of the heterobimetallic compounds. The polymer with alternating copper-NHC and silver-NHC units and a flexible methylene-triazole bridge between them shows the highest activity in the catalytic alkynylation of trifluoromethyl ketones to give fluorinated propargylic alcohols. PMID:27331787

  8. 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

  9. Exfoliated Pd/HNb3O8 nanosheet as highly efficient bifunctional catalyst for one-pot cascade reaction

    NASA Astrophysics Data System (ADS)

    Lee, Nahaeng; Chung, Young-Min

    2016-05-01

    Ultrathin two-dimensional metal oxide nanosheets have drawn attention as potential solid acid catalysts owing to their strong acidity, attributed to the bridged OH groups formed on the nanosheets. In this study, a new class of bifunctional acid-metal catalyst was realized by the deposition of Pd on layered niobium oxide (KNb3O8 and HNb3O8) or its exfoliated nanosheet (Pd/HNb3O8-NS) and applied to one-pot cascade deacetalization and hydrogenation. It was found that the acid strength of the support exerted a large influence not only on the promotion of the first deacetalization step, but also on the acceleration of the subsequent hydrogenation step. Comparative experiments using a series of Pd/HZSM-5 catalysts with different acidities reconfirmed the crucial role of acid strength on hydrogenation. However, the superior catalytic activity of Pd/HNb3O8-NS for hydrogenation compared to that of Pd/HZSM-5 of similar acidity suggests a more efficient ensemble effect of the strong acid sites with the nearby metal sites on the nanosheet surface. Among the catalysts used, Pd/HNb3O8-NS showed the best catalytic performance for one-pot cascade reaction affording the desired product (benzyl alcohol) in approximately 92% yield, which was 7.1 and 1.2 times higher than that of layered Pd/KNb3O8 or Pd/HNb3O8, respectively. The excellent catalytic performance of Pd/HNb3O8-NS may result from the characteristic features of nanosheets: (i) the synergistic cooperation between the bifunctional active sites and (ii) the two-dimensional open surface offering easier access of the reactants to the active sites. Although the use of NaBH4 as hydrogen source was effective in improving the initial reaction performance, the basic nature of NaBH4 adversely resulted in weakening the acid strength of the catalyst, and consequently led to a reduction in catalytic activity.

  10. 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.

  11. Magnetic bearings grow more attractive

    SciTech Connect

    Not Available

    1993-10-01

    Advances in materials and electronics have enabled designers to devise simpler, smaller magnetic bearings. As a result, costs have dropped, widening the applications for these very-low-friction devices. Avcon (Advanced Controls Technology) has patented a permanent-magnet bias actively controlled bearing. Here high-energy rare earth permanent-magnet materials supply the basic bearing load levitation, while servo-driven electromagnets generate stabilization and centering forces for motion contol. Previous heavy-duty magnetic bearings used electromagnets entirely for suspension and control, which led to large bearings and control systems with higher power requirements. Avcon has developed several types of permanent-magnet bias bearings. The simplest is the radial repulsion bearing. Avcon's homopolar permanent-magnet bias active bearing is the most versatile of the company's designs.

  12. Interference-Fit Life Factors for Roller Bearings

    NASA Technical Reports Server (NTRS)

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

    2009-01-01

    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 7 fit classes for each of 10 bearing sizes. The hoop stresses were superimposed on the Hertzian principal stresses created by the applied radial load to calculate roller bearing fatigue life. A method was developed through a series of equations to calculate the life reduction for cylindrical roller bearings. All calculated lives are for zero initial internal clearance. Any reduction in bearing clearance due to interference fit would be 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 for bearing accuracy class RBEC-5 (ISO class 5). Interference fits on the inner 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 tolerance band 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.

  13. Cloning, primary structure, and regulation of the HIS7 gene encoding a bifunctional glutamine amidotransferase: cyclase from Saccharomyces cerevisiae.

    PubMed Central

    Kuenzler, M; Balmelli, T; Egli, C M; Paravicini, G; Braus, G H

    1993-01-01

    The Saccharomyces cerevisiae HIS7 gene was cloned by its location immediately downstream of the previously isolated and characterized ARO4 gene. The two genes have the same orientation with a distance of only 416 bp between the two open reading frames. The yeast HIS7 gene represents the first isolated eukaryotic gene encoding the enzymatic activities which catalyze the fifth and sixth step in histidine biosynthesis. The open reading frame of the HIS7 gene has a length of 1,656 bp resulting in a gene product of 552 amino acids with a calculated molecular weight of 61,082. Two findings implicate a bifunctional nature of the HIS7 gene product. First, the N-terminal and C-terminal segments of the deduced HIS7 amino acid sequence show significant homology to prokaryotic monofunctional glutamine amidotransferases and cyclases, respectively, involved in histidine biosynthesis. Second, the yeast HIS7 gene is able to suppress His auxotrophy of corresponding Escherichia coli hisH and hisF mutants. HIS7 gene expression is regulated by the general control system of amino acid biosynthesis. GCN4-dependent and GCN4-independent (basal) transcription use different initiator elements in the HIS7 promoter. Images PMID:8366040

  14. Increasing round trip efficiency of hybrid Li-air battery with bifunctional catalysts

    SciTech Connect

    Huang, K; Li, YF; Xing, YC

    2013-07-30

    Previously it was shown that Pt as cathode catalyst ha's a large overpotential during charge in rechargeable hybrid Li-air battery with sulfuric acid catholyte. This article demonstrates that a bifunctional catalyst composed of Pt and IrO2 supported on carbon nanotubes can address this problem. The specially designed and synthesized bifunctional catalyst showed significant overpotential reduction and achieved a round trip energy efficiency of 81% after 10 cycles, higher than many achieved in aprotic Li-O-2 batteries. The hybrid Li-air battery was discharged and recharged for 20 cycles at 0.2 mA/cm(2), showing a fairly stable cell performance. A specific capacity of 306 mAh/g and a specific energy of 1110 Wh/kg were obtained for the hybrid Li-air battery in terms of acid weight. (c) 2013 Elsevier Ltd. All rights reserved.

  15. Externally Pressurized Journal Gas Bearings

    NASA Technical Reports Server (NTRS)

    Laub, John H.

    1959-01-01

    Externally pressurized gas-lubricated bearings with multiple orifice feed are investigated. An analytical treatment is developed for a semi-cylindrical bearing with 9 orifices and for a cylindrical journal bearing with 192 radial and 24 axial orifices. Experiments are described on models of the two bearing configurations with specially designed fixtures which incorporate pneumatic loading and means for determining pressure profiles, gas flow and gap height. The correlation between theory and experiment is satisfactory.

  16. Passive magnetic bearing system

    DOEpatents

    Post, Richard F.

    2014-09-02

    An axial stabilizer for the rotor of a magnetic bearing provides external control of stiffness through switching in external inductances. External control also allows the stabilizer to become a part of a passive/active magnetic bearing system that requires no external source of power and no position sensor. Stabilizers for displacements transverse to the axis of rotation are provided that require only a single cylindrical Halbach array in its operation, and thus are especially suited for use in high rotation speed applications, such as flywheel energy storage systems. The elimination of the need of an inner cylindrical array solves the difficult mechanical problem of supplying support against centrifugal forces for the magnets of that array. Compensation is provided for the temperature variation of the strength of the magnetic fields of the permanent magnets in the levitating magnet arrays.

  17. Magnetic bearing and motor

    NASA Technical Reports Server (NTRS)

    Studer, Philip A. (Inventor)

    1983-01-01

    A magnetic bearing assembly (10) has an intermediate rotatable section (33) having an outer cylindrical member (30) coaxially suspended by a torsion wire (72) around an axially polarized cylindrical magnet (32). Axial alignment between the pole faces (40-43) of the intermediate section (33) and end surfaces (50-53) of opposed end bells (20, 22) provides a path of least reluctance across intervening air gaps (60-63) for the magnetic flux emanating from magnet (32). Radial dislocation increases the reluctance and creates a radial restoring force. Substitution of radially polarized magnets 107 fixed to a magnetically permeable cylinder (32') and insertion of pairs of armature coil windings (109-112) between the cylinder pair (33') provides an integral magnetic bearing and torsion motor (100) able to provide arcuately limited rotational drive.

  18. Centrifugally decoupling touchdown bearings

    DOEpatents

    Post, Richard F

    2014-06-24

    Centrifugally decoupling mechanical bearing systems provide thin tensioned metallic ribbons contained in a support structure. This assembly rotates around a stationary shaft being centered at low speeds by the action of the metal ribbons. Tension springs are connected on one end to the ribbons and on the other end to the support structure. The ribbons pass through slots in the inner ring of the support structure. The spring preloading thus insures contact (or near-contact) between the ribbons and the shaft at rotation speeds below the transition speed. Above this speed, however, the centrifugal force on the ribbons produces a tensile force on them that exceeds the spring tensile force so that the ribbons curve outward, effectively decoupling them from mechanical contact with the shaft. They still remain, however, in position to act as a touchdown bearing in case of abnormally high transverse accelerations.

  19. Rotating plug bearing and seal

    DOEpatents

    Wade, Elman E.

    1977-01-01

    A bearing and seal structure for nuclear reactors utilizing rotating plugs above the nuclear reactor vessel. The structure permits lubrication of bearings and seals of the rotating plugs without risk of the lubricant draining into the reactor vessel below. The structure permits lubrication by utilizing a rotating outer race bearing.

  20. Frictionless Bearing Uses Permanent Magnets

    NASA Technical Reports Server (NTRS)

    1965-01-01

    The purpose of this innovation was to develop a frictionless bearing for high speed, light load applications. The device involves the incorporation of permanent magnets in the bearing design. The repulsion of like magnetic poles provides concentric support of the inner member so that no metallic contact occurs between the bearing surfaces.

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

    SciTech Connect

    Yu, Xiaofang; Zou, Yongcun; Wu, Shujie; Liu, Heng; Guan, Jingqi; Kan, Qiubin

    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.

  2. Porous cobalt-based thin film as a bifunctional catalyst for hydrogen generation and oxygen generation.

    PubMed

    Yang, Yang; Fei, Huilong; Ruan, Gedeng; Tour, James M

    2015-05-27

    A mixed-phased Co-based catalyst composed of Co phosphide and Co phosphate is successfully fabricated for bifunctional water electrolysis. The highly porous morphology in this anodized film enables efficient catalytic activity toward water splitting in an extremely low loading mass. The mixed phases in the porous film afford an ability to generate both H2 and O2 in a single electrolyzer. PMID:25872881

  3. Highly enantioselective conjugate addition of malononitrile to 2-enoylpyridines with bifunctional organocatalyst.

    PubMed

    Molleti, Nagaraju; Rana, Nirmal K; Singh, Vinod K

    2012-09-01

    An efficient enantioselective conjugate addition of malononitrile to a range of β-substituted 2-enoylpyridines catalyzed by cinchona alkaloid-based bifunctional urea catalysts has been developed. Both enantiomers of the products could be achieved with the same level of enantioselectivity by using pseudoenantiomeric catalysts in up to 97% ee and in excellent yields. One of the enantioenriched products has been transformed to a highly functionalized piperidone derivative. PMID:22920458

  4. 3D Ordered Mesoporous Bifunctional Oxygen Catalyst for Electrically Rechargeable Zinc-Air Batteries.

    PubMed

    Park, Moon Gyu; Lee, Dong Un; Seo, Min Ho; Cano, Zachary Paul; Chen, Zhongwei

    2016-05-01

    To enhance energy efficiency and durability, a highly active and durable 3D ordered mesoporous cobalt oxide framework has been developed for rechargeable zinc-air batteries. The bifunctional air electrode consisting of 3DOM Co3 O4 having high active surface area and robust structure, results in superior charge and discharge battery voltages, and durable performance for electrically rechargeable zinc-air batteries. PMID:27043451

  5. L-Proline Derived Bifunctional Organocatalysts: Enantioselective Michael Addition of Dithiomalonates to trans-β-Nitroolefins.

    PubMed

    Jin, Hui; Kim, Seung Tae; Hwang, Geum-Sook; Ryu, Do Hyun

    2016-04-15

    A series of novel L-proline derived tertiary amine bifunctional organocatalysts 9 are reported, which were applied to the asymmetric Michael addition of dithiomalonates 2 to trans-β-nitroolefins 1. The reaction proceeded in high yields (up to 99%) with high enantioselectivities (up to 97% ee). The synthetic utility of this methodology was demonstrated in the short synthesis of (R)-phenibut in high yield. PMID:26989804

  6. Big Bear Solar Observatory

    NASA Astrophysics Data System (ADS)

    Murdin, P.

    2000-11-01

    Big Bear Solar Observatory (BBSO) is located at the end of a causeway in a mountain lake more than 2 km above sea level. The site has more than 300 sunny days a year and a natural inversion caused by the lake which makes for very clean images. BBSO is the only university observatory in the US making high-resolution observations of the Sun. Its daily images are posted at http://www.bbso.njit.e...

  7. Radium bearing waste disposal

    SciTech Connect

    Tope, W.G.; Nixon, D.A.; Smith, M.L.; Stone, T.J.; Vogel, R.A.; Schofield, W.D.

    1995-07-01

    Fernald radium bearing ore residue waste, stored within Silos 1 and 2 (K-65) and Silo 3, will be vitrified for disposal at the Nevada Test Site (NTS). A comprehensive, parametric evaluation of waste form, packaging, and transportation alternatives was completed to identify the most cost-effective approach. The impacts of waste loading, waste form, regulatory requirements, NTS waste acceptance criteria, as-low-as-reasonably-achievable principles, and material handling costs were factored into the recommended approach.

  8. Magnetic translator bearings

    NASA Technical Reports Server (NTRS)

    Hockney, Richard L. (Inventor); Downer, James R. (Inventor); Eisenhaure, David B. (Inventor); Hawkey, Timothy J. (Inventor); Johnson, Bruce G. (Inventor)

    1990-01-01

    A magnetic bearing system for enabling translational motion includes a carriage and a shaft for movably supporting the carriage; a first magnetic bearing fixed to one of the carriage and shaft and slidably received in a first channel of the other of the carriage and shaft. The first channel is generally U shaped with two side walls and a back wall. The magnetic bearing includes a pair of spaced magnetic pole pieces, each pole piece having a pair of electromagnetic coils mounted on poles on opposite ends of the pole piece proximate the side walls, and a third electromagnetic coil mounted on a pole of the pole piece proximate the backwall; a motion sensor for sensing translational motion along two axes and rotationally about three axes of the carriage and shaft relative to each other; and a correction circuit responsive to the sensor for generating a correction signal to drive the coils to compensate for any misalignment sensed between the carriage and the shaft.

  9. The series hybrid bearing - A new high speed bearing concept.

    NASA Technical Reports Server (NTRS)

    Anderson, W. J.; Fleming, D. P.; Parker, R. J.

    1971-01-01

    The series-hybrid bearing couples a fluid-film bearing with a rolling-element bearing such that the rolling-element bearing inner race runs at a fraction of shaft speed. A series-hybrid bearing was analyzed and experiments were run at thrust loads from 100 to 300 lb and speeds from 4000 to 30,000 rpm. Agreement between theoretical and experimental speed sharing was good. The lowest speed ratio (ratio of ball bearing inner-race speed to shaft speed) obtained was 0.67. This corresponds to an approximate reduction in DN value of 1/3. For a ball bearing in a 3 million DN application, fatigue life would theoretically be improved by a factor as great as 8.

  10. Evolution of a bifunctional enzyme: 6-phosphofructo-2-kinase/fructose-2,6-bisphosphatase.

    PubMed Central

    Bazan, J F; Fletterick, R J; Pilkis, S J

    1989-01-01

    The bifunctional rat liver enzyme 6-phosphofructo-2-kinase/fructose-2,6-bisphosphatase (ATP:D-fructose-6-phosphate 2-phosphotransferase/D-fructose-2,6-bisphosphate 2-phosphohydrolase, EC 2.7.1.105/EC 3.1.3.46) is constructed of two independent catalytic domains. We present evidence that the kinase and bisphosphatase halves of the bifunctional enzyme are, respectively, structurally similar to the glycolytic enzymes 6-phosphofructo-1-kinase and phosphoglycerate mutase. Computer-assisted modeling of the C-terminal bisphosphatase domain reveals a hydrophobic core and active site residue constellation equivalent to the yeast mutase structure; structural differences map to length-variable, surface-located loops. Sequence patterns derived from the structural alignment of mutases and the bisphosphatase further detect a significant similarity to a family of acid phosphatases. The N-terminal kinase domain, in turn, is predicted to form a nucleotide-binding fold that is analogous to a segment of 6-phosphofructo-1-kinase, suggesting that these unrelated enzymes bind fructose 6-phosphate and ATP substrates in a similar geometry. This analysis indicates that the bifunctional enzyme is the likely product of gene fusion of kinase and mutase/phosphatase catalytic units. Images PMID:2557623

  11. Bifunctional Perovskite Oxide Catalysts for Oxygen Reduction and Evolution in Alkaline Media.

    PubMed

    Gupta, Shiva; Kellogg, William; Xu, Hui; Liu, Xien; Cho, Jaephil; Wu, Gang

    2016-01-01

    Oxygen electrocatalysis, namely of the oxygen reduction reaction (ORR) and the oxygen evolution reaction (OER), governs the performance of numerous electrochemical energy systems such as reversible fuel cells, metal-air batteries, and water electrolyzers. However, the sluggish kinetics of these two reactions and their dependency on expensive noble metal catalysts (e.g, Pt or Ir) prohibit the sustainable commercialization of these highly innovative and in-demand technologies. Bifunctional perovskite oxides have emerged as a new class of highly efficient non-precious metal catalysts (NPMC) for oxygen electrocatalysis in alkaline media. In this review, we discuss the state-of-the-art understanding of bifunctional properties of perovskites with regards to their OER/ORR activity in alkaline media and review the associated reaction mechanisms on the oxides surface and the related activity descriptors developed in the recent literature. We also summarize the present strategies to modify their electronic structure and to further improve their performance for the ORR/OER through highlighting the new concepts relating to the role of surface redox chemistry and oxygen deficiency of perovskite oxides for the ORR/OER activity. In addition, we provide a brief account of recently developed advanced perovskite-nanocarbon hybrid bifunctional catalysts with much improved performances. PMID:26247625

  12. Comparison of Dynamical Behaviors Between Monofunctional and Bifunctional Two-Component Signaling Modules

    NASA Astrophysics Data System (ADS)

    Yang, Xiyan; Wu, Yahao; Yuan, Zhanjiang

    2015-06-01

    Two-component signaling modules exist extensively in bacteria and microbes. These modules can be, based on their distinct network structures, divided into two types: the monofunctional system (denoted by MFS) where the sensor kinase (SK) modulates only phosphorylation of the response regulator (RR), and the bifunctional system (denoted by BFS) where the SK catalyzes both phosphorylation and dephosphorylation of the RR. Here, we analyze dynamical behaviors of these two systems based on stability theory, focusing on differences between them. The analysis of the deterministic behavior indicates that there is no difference between the two modules, that is, each system has the unique stable steady state. However, there are significant differences in stochastic behavior between them. Specifically, if the mean phosphorylated SK level is kept the same for the two modules, then the variance and the Fano factor for the phosphorylated RR in the BFS are always no less than those in the MFS, indicating that bifunctionality always enhances fluctuations. The correlation between the phosphorylated SK and the phosphorylated RR in the BFS is always positive mainly due to competition between system components, but this correlation in the MFS may be positive, almost zero, or negative, depending on the ratio between two rate constants. Our overall analysis indicates that differences between dynamical behaviors of monofunctional and bifunctional signaling modules are mainly in the stochastic rather than deterministic aspect.

  13. 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 (ΔE) 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

  14. Enhanced Bifunctional Oxygen Catalysis in Strained LaNiO3 Perovskites

    DOE PAGESBeta

    Petrie, Jonathan R.; Cooper, Valentino R.; Freeland, John W.; Meyer, Tricia L.; Zhang, Zhiyong; Lutterman, Daniel A.; Lee, Ho Nyung

    2016-02-11

    Strain is known to greatly influence low-temperature oxygen electrocatalysis on noble metal films, leading to significant enhancements in bifunctional activity essential for fuel cells and metal-air batteries. Still, its catalytic impact on transition-metal oxide thin films, such as perovskites, is not widely understood. Here, we epitaxially strain the conducting perovskite LaNiO3 to systematically determine its influence on both the oxygen reduction and oxygen evolution reaction. Uniquely, we found that compressive strain could significantly enhance both reactions, yielding a bifunctional catalyst that surpasses the performance of noble metals such as Pt. We attribute the improved bifunctionality to strain-induced splitting of themore » eg orbitals, which can customize orbital asymmetry at the surface. Lastly, analogous to strain-induced shifts in the d-band center of noble metals relative to the Fermi level, such splitting can dramatically affect catalytic activity in this perovskite and other potentially more active oxides.« less

  15. Mechanical Characterization of a Bi-functional Tetronic Hydrogel Adhesive for Soft Tissues

    PubMed Central

    Sanders, Lindsey; Stone, Roland; Webb, C. Kenneth; Mefford, O. Thompson; Nagatomi, Jiro

    2014-01-01

    Although a number of tissue adhesives and sealants for surgical use are currently available, attaining a useful balance in high strength, high compliance, and low swelling has proven difficult. Recent studies have demonstrated that a 4-arm poly(propylene oxide)-poly(ethylene oxide) (PPO-PEO) block copolymer, Tetronic, can be chemically modified to form a hydrogel tissue adhesive21–23. Building on the success of these studies, the present study explored bi-functionalization of Tetronic with acrylates for chemical crosslinking of the hydrogel and N-hydroxysuccinimide (NHS) for reaction with tissue amines. The adhesive bond strengths of various uni- and bi-functional Tetronic blends (T1107 ACR: T1107 ACR/NHS) determined by lap shear testing ranged between 8 and 74 kPa, with the 75:25 (T1107 ACR: T1107 ACR/NHS) blend displaying the highest value. These results indicated that addition of NHS led to improvement of tissue bond strength over acrylation alone Furthermore, ex vivo pressure tests using the rat bladder demonstrated that the bi-functional Tetronic adhesive exhibited high compliance and maintained pressures under hundreds of filling and emptying cycles. Together, the results of the present study provided evidence that the bi-functional Tetronic adhesive with a proper blend ratio may be used to achieve an accurate balance in bulk and tissue bond strengths, as well as the compliance and durability for soft tissue such as the bladder. PMID:25111445

  16. (S)-5-(p-Nitrobenzyl)-PCTA, a Promising Bifunctional Ligand with Advantageous Metal Ion Complexation Kinetics

    PubMed Central

    Tircsó, Gyula; Benyó, Enikő Tircsóné; Suh, Eul Hyun; Jurek, Paul; Kiefer, Garry E.; Sherry, A. Dean; Kovács, Zoltán

    2009-01-01

    A bifunctional version of PCTA (3,6,9,15-tetraazabicyclo[9.3.1]pentadeca-1(15),11,13-triene-3,6,9,-triacetic acid) that exhibits fast complexation kinetics with the trivalent lanthanide(III) ions was synthesized in reasonable yields starting from N, N′, N″-tristosyl-(S)-2-(p-nitrobenzyl)-diethylenetriamine. pH-potentiometric studies showed that the basicities of p-nitrobenzyl-PCTA and the parent ligand PCTA were similar. The stability of M(NO2-Bn-PCTA) (M = Mg2+, Ca2+, Cu2+, Zn2+) complexes was similar to that of the corresponding PCTA complexes while the stability of Ln3+ complexes of the bifunctional ligand is somewhat lower than that of PCTA chelates. The rate of complex formation of Ln(NO2-Bn-PCTA) complexes was found to be quite similar to that of PCTA, a ligand known to exhibit the fastest formation rates among all lanthanide macrocyclic ligand complexes studied to date. The acid catalyzed decomplexation kinetic studies of the selected Ln(NO2-Bn-PCTA) complexes showed that the kinetic inertness of the complexes was comparable to that of Ln(DOTA) chelates making the bifunctional ligand NO2-Bn-PCTA suitable for labeling biological vectors with radioisotopes for nuclear medicine applications. PMID:19220012

  17. 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.

  18. Bearing for liquid metal pump

    DOEpatents

    Dickinson, Robert J.; Wasko, John; Pennell, William E.

    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.

  19. Bearing, gearing, and lubrication technology

    NASA Technical Reports Server (NTRS)

    Anderson, W. J.

    1978-01-01

    Results of selected NASA research programs on rolling-element and fluid-film bearings, gears, and elastohydrodynamic lubrication are reported. Advances in rolling-element bearing material technology, which have resulted in a significant improvement in fatigue life, and which make possible new applications for rolling bearings, are discussed. Research on whirl-resistant, fluid-film bearings, suitable for very high-speed applications, is discussed. An improved method for predicting gear pitting life is reported. An improved formula for calculating the thickness of elastohydrodynamic films (the existence of which help to define the operating regime of concentrated contact mechanisms such as bearings, gears, and cams) is described.

  20. Plain bearing stresses due to forming and oil film pressure

    NASA Astrophysics Data System (ADS)

    Burke-Veliz, A.; Wang, D.; Wahdy, N.; Reed, P. A. S.; Merritt, D.; Syngellakis, S.

    2009-08-01

    This paper describes a methodology for assessing critical stress ranges arising in automotive plain bearings during engine operations. An industry-produced and run simulation program provides information on oil film pressure and overall bearing deformation during accelerated performance tests. This code performs an elasto-hydrodynamic lubrication analysis accounting for the compliance of the housing and journal. Finite element analyses of a multilayer bearing are performed to assess the conditions responsible for possible fatigue damage over the bearing lining. The residual stresses arising from the forming and fitting process are first assessed. The stress analyses over the engine cycle show the intensity and distribution of cyclic tensile and compressive stresses in the bearing. The location of maximum stress range is found to be consistent with the damage observed in accelerated fatigue tests. Critical zones are identified in the lining for possible fatigue crack initiation and growth studies.

  1. Bearing construction for refrigeration compressor

    SciTech Connect

    Middleton, M.G.; Nelson, R.T.

    1988-01-12

    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. 4 figs.

  2. Bearing construction for refrigeration compresssor

    DOEpatents

    Middleton, Marc G.; Nelson, Richard T.

    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.

  3. Damping Bearings In High-Speed Turbomachines

    NASA Technical Reports Server (NTRS)

    Von Pragenau, George L.

    1994-01-01

    Paper presents comparison of damping bearings with traditional ball, roller, and hydrostatic bearings in high-speed cryogenic turbopumps. Concept of damping bearings described in "Damping Seals and Bearings for a Turbomachine" (MFS-28345).

  4. 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.

  5. Introgressive hybridization: brown bears as vectors for polar bear alleles.

    PubMed

    Hailer, Frank

    2015-03-01

    The dynamics and consequences of introgression can inform about numerous evolutionary processes. Biologists have therefore long been interested in hybridization. One challenge, however, lies in the identification of nonadmixed genotypes that can serve as a baseline for accurate quantification of admixture. In this issue of Molecular Ecology, Cahill et al. (2015) analyse a genomic data set of 28 polar bears, eight brown bears and one American black bear. Polar bear alleles are found to be introgressed into brown bears not only near a previously identified admixture zone on the Alaskan Admiralty, Baranof and Chichagof (ABC) Islands, but also far into the North American mainland. Elegantly contrasting admixture levels at autosomal and X chromosomal markers, Cahill and colleagues infer that male-biased dispersal has spread these introgressed alleles away from the Late Pleistocene contact zone. Compared to a previous study on the ABC Island population in which an Alaskan brown bear served as a putatively admixture-free reference, Cahill et al. (2015) utilize a newly sequenced Swedish brown bear as admixture baseline. This approach reveals that brown bears have been impacted by introgression from polar bears to a larger extent (up to 8.8% of their genome), than previously known, including the bear that had previously served as admixture baseline. No evidence for introgression of brown bear into polar bear is found, which the authors argue could be a consequence of selection. Besides adding new exciting pieces to the puzzle of polar/brown bear evolutionary history, the study by Cahill and colleagues highlights that wildlife genomics is moving from analysing single genomes towards a landscape genomics approach. PMID:25775930

  6. Gold-bearing skarns

    USGS Publications Warehouse

    Theodore, Ted G.; Orris, Greta J.; Hammerstrom, Jane M.; Bliss, James D.

    1991-01-01

    In recent years, a significant proportion of the mining industry's interest has been centered on discovery of gold deposits; this includes discovery of additional deposits where gold occurs in skarn, such as at Fortitude, Nevada, and at Red Dome, Australia. Under the classification of Au-bearing skarns, we have modeled these and similar gold-rich deposits that have a gold grade of at least 1 g/t and exhibit distinctive skarn mineralogy. Two subtypes, Au-skarns and byproduct Au-skarns, can be recognized on the basis of gold, silver, and base-metal grades, although many other geological factors apparently are still undistinguishable largely because of a lack of detailed studies of the Au-skarns. Median grades and tonnage for 40 Au-skarn deposits are 8.6 g/t Au, 5.0 g/t Ag, and 213,000 t. Median grades and tonnage for 50 byproduct and Au-skarn deposits are 3.7 g/t Au, 37 g/t Ag, and 330,000 t. Gold-bearing skarns are generally calcic exoskarns associated with intense retrograde hydrosilicate alteration. These skarns may contain economic amounts of numerous other commodities (Cu, Fe, Pb, Zn, As, Bi, W, Sb, Co, Cd, and S) as well as gold and silver. Most Au-bearing skarns are found in Paleozoic and Cenozoic orogenic-belt and island-arc settings and are associated with felsic to intermediate intrusive rocks of Paleozoic to Tertiary age. Native gold, electru, pyrite, pyrrhotite, chalcopyrite, arsenopyrite, sphalerite, galena, bismuth minerals, and magnetite or hematite are the most common opaque minerals. Gangue minerals typically include garnet (andradite-grossular), pyroxene (diopside-hedenbergite), wollastonite, chlorite, epidote, quartz, actinolite-tremolite, and (or) calcite.

  7. Linear magnetic bearings

    NASA Technical Reports Server (NTRS)

    Goldowskiy, M. P.

    1984-01-01

    A self regulating, nonfrictional, active magnetic bearing is disclosed which has an elongated cylindrical housing for containing a shaft type armature with quadrature positioned shaft position sensors and equidistantly positioned electromagnets located at one end of the housing. Each set of sensors is responsive to orthogonal displacement of the armature and is used to generate control signals to energize the electromagnets to center the armature. A bumper magnet assembly is located at one end of the housing for dampening any undesired axial movement of the armature or to axially move the armature either continuously or fixedly.

  8. Exon-Specific U1s Correct SPINK5 Exon 11 Skipping Caused by a Synonymous Substitution that Affects a Bifunctional Splicing Regulatory Element.

    PubMed

    Dal Mas, Andrea; Fortugno, Paola; Donadon, Irving; Levati, Lauretta; Castiglia, Daniele; Pagani, Franco

    2015-05-01

    The c.891C>T synonymous transition in SPINK5 induces exon 11 (E11) skipping and causes Netherton syndrome (NS). Using a specific RNA-protein interaction assay followed by mass spectrometry analysis along with silencing and overexpression of splicing factors, we showed that this mutation affects an exonic bifunctional splicing regulatory element composed by two partially overlapping silencer and enhancer sequences, recognized by hnRNPA1 and Tra2β splicing factors, respectively. The C-to-T substitution concomitantly increases hnRNPA1 and weakens Tra2β-binding sites, leading to pathological E11 skipping. In hybrid minigenes, exon-specific U1 small nuclear RNAs (ExSpe U1s) that target by complementarity intronic sequences downstream of the donor splice site rescued the E11 skipping defect caused by the c.891C>T mutation. ExSpe U1 lentiviral-mediated transduction of primary NS keratinocytes from a patient bearing the mutation recovered the correct full-length SPINK5 mRNA and the corresponding functional lympho-epithelial Kazal-type related inhibitor protein in a dose-dependent manner. This study documents the reliability of a mutation-specific, ExSpe U1-based, splicing therapy for a relatively large subset of European NS patients. Usage of ExSpe U1 may represent a general approach for correction of splicing defects affecting skin disease genes. PMID:25665175

  9. A Bifunctional Thioether Linked Coumarin Appended Calix[4]arene Acquires Selectivity Toward Cu(2+) Sensing on Going from Solution to SAM on Gold.

    PubMed

    Samanta, Kushal; Rao, Chebrolu Pulla

    2016-02-10

    A bifunctional calix[4]arene molecule bearing coumarin moiety on the lower rim and thioether moiety on the upper rim (L1), has been synthesized and well characterized by (1)H, (13)C NMR and mass spectrometry. Suitably functionalized coumarin moieties are well suited for selective recognition of various cations and anions. Among the 10 different metal ions studied, only Cu(2+) and Fe(3+) exhibit appreciable changes in the absorption spectra owing to the availability of functional moieties present at both the lower as well as the upper rim of free L1 in acetonitrile solution. To bring better selectivity, we blocked one of these functional moieties by coating on to a surface so that only the other one is exposed to the environment for sensing. Such a study carried out in the present case using the self-assembled monolayer (SAM) of L1 on Au(111) resulted in selective sensing of Cu(2+) over several other metal ions as studied by surface plasmon resonance (SPR). The SAM of L1 on Au(111) was confirmed by different techniques, such as grazing incidence FT-IR, contact angle measurement, cyclic voltammetry and scanning tunneling microscopy. Thus, L1 is proven to be a suitable sensor for Cu(2+) when attached to gold surface. PMID:26771103

  10. 6-Azido-6-deoxy-l-idose as a Hetero-Bifunctional Spacer for the Synthesis of Azido-Containing Chemical Probes.

    PubMed

    Hamagami, Hiroki; Kumazoe, Motofumi; Yamaguchi, Yoshiki; Fuse, Shinichiro; Tachibana, Hirofumi; Tanaka, Hiroshi

    2016-08-26

    The design of 6-azido-6-deoxy-l-idose for use as a hetero-bifunctional spacer is reported. The hemiacetal at one terminus is an equivalent of an aldehyde and can react with nucleophiles, such as amino groups and electron-rich aromatics. The azido group at the other terminus bio-orthogonally undergoes a Hüisgen [3+2] cycloaddition with an acetylene. The idose derivative exhibited a higher level of reactivity towards oxime formation than a corresponding glucose derivative. The (13) C NMR spectrum of the uniformly (13) C-labeled 6-azido-idose indicated that the acyclic forms of the sugar totaled 0.3 % of all the isomers, whereas those of glucose totaled 0.01 %. The larger population of the acyclic forms of the idose derivative would result in higher reactivity towards electrophilic addition in comparison with glucose derivatives. Finally, we prepared a C-idosyl epigallocatechin gallate (EGCG) that bears an azido group through C-glycosylation of EGCG with 6-azido-idose. This glycosyl form of the C-idosyl EGCG exhibited a cytotoxicity against U266 cells that was comparable to that of EGCG. These results suggested that the EGCG derivative could be used as an effective chemical probe for the elucidation of EGCG biological functions. PMID:27482948

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

    SciTech Connect

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

    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.

  12. 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.

  13. 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.

  14. 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.

  15. DEVELOPMENT OF A HYDROSTATIC JOURNAL BEARING WITH SLIT-STEP COMPENSATION

    SciTech Connect

    Hale, L C; Donaldson, R R; Castro, C; Chung, C A; Hopkins, D J

    2006-07-28

    This paper describes the mathematical modeling and initial testing of an oil-hydrostatic bearing that derives compensation from both a central radial slit where fluid enters and stepped clearances near each end. Bearings using either a radial slit or stepped clearances for compensation were well studied over forty years ago by Donaldson. These bearings have smooth bores uninterrupted with multiple recesses around the circumference. The present slit-step bearing achieves the best of both types with somewhat higher hydrostatic stiffness than the slit bearing and fluid shear drag lower than the step bearing. This is apparent in TABLE 1, which compares calculated values of initial (i.e., centered) hydrostatic stiffness for each type. The slit-step bearing is one of several types being studied at Lawrence Livermore National Laboratory for possible use on the Precision Optical Grinder and Lathe (POGAL).

  16. 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.

  17. Reduction in bearing size due to superconductors in magnetic bearings

    NASA Technical Reports Server (NTRS)

    Rao, Dantam K.; Lewis, Paul; Dill, James F.

    1991-01-01

    A design concept that reduces the size of magnetic bearings is assessed. The small size will enable magnetic bearings to fit into limited available bearing volume of cryogenic machinery. The design concept, called SUPERC, uses (high Tc) superconductors or high-purity aluminum conductors in windings instead of copper. The relatively high-current density of these conductors reduces the slot radial thickness for windings, which reduces the size of the bearings. MTI developed a sizing program called SUPERC that translates the high-current density of these conductors into smaller sized bearings. This program was used to size a superconducting bearing to carry a 500 lb. load. The sizes of magnetic bearings needed by various design concepts are as follows: SUPERC design concept = 3.75 in.; magnet-bias design concept = 5.25 in.; and all electromagnet design concept = 7.0 in. These results indicate that the SUPERC design concept can significantly reduce the size of the bearing. This reduction, in turn, reduces the weight and yields a lighter bearing. Since the superconductors have inherently near-zero resistance, they are also expected to save power needed for operation considerably.

  18. Unusual non-bifunctional mechanism for Co-PNP complex catalyzed transfer hydrogenation governed by the electronic configuration of metal center.

    PubMed

    Hou, Cheng; Jiang, Jingxing; Li, Yinwu; Zhang, Zhihan; Zhao, Cunyuan; Ke, Zhuofeng

    2015-10-01

    The mimic of hydrogenases has unleashed a myriad of bifunctional catalysts, which are widely used in the catalytic hydrogenation of polar multiple bonds. With respect to ancillary ligands, the bifunctional mechanism is generally considered to proceed via the metal-ligand cooperation transition state. Inspired by the interesting study conducted by Hanson et al. (Chem Commun., 2013, 49, 10151), we present a computational study of a distinctive example, where a Co(II)-PNP catalyst with an ancillary ligand exhibits efficient transfer hydrogenation through a non-bifunctional mechanism. Both the bifunctional and non-bifunctional mechanisms are discussed. The calculated results, which are based on a full model of the catalyst, suggest that the inner-sphere non-bifunctional mechanism is more favorable (by ∼11 kcal mol(-1)) than the outer-sphere bifunctional mechanism, which is in agreement with the experimental observations. The origin of this mechanistic preference of the Co(II)-PNP catalyst can be attributed to its preference for the square planar geometry. A traditional bifunctional mechanism is less plausible for Co(II)-PNP due to the high distortion energy caused by the change in electronic configuration with the varied ligand field. Considering previous studies that focus on the development of ligands more often, this computational study indicates that the catalytic hydrogenation mechanism is controlled not only by the structure of the ligand but also by the electronic configuration of the metal center. PMID:26332273

  19. Series-hybrid bearing - An approach to extending bearing fatigue life at high speeds

    NASA Technical Reports Server (NTRS)

    Anderson, W. J.; Coe, H. H.; Fleming, D. P.; Parker, R. J.

    1971-01-01

    Fluid film bearing of hybrid device consists of orifice compensated annular thrust bearing and self-acting journal bearing. In series hybrid bearing, both ball bearing and annular thrust bearing carry full system thrust load, but two bearings share speed. Operation of system is stable and automatically fail-safe.

  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. Unidirectional Adsorption of Bifunctional 1,4-Phenylene Diisocyanide on the Ge(100)-2 × 1 Surface.

    PubMed

    Shong, Bonggeun; Sandoval, Tania E; Crow, Allison M; Bent, Stacey F

    2015-03-19

    Adsorption of bifunctional organic molecules on semiconductor surfaces is important for surface modification; however, most bifunctional molecules previously studied have yielded mixtures of singly and dually tethered adsorbates. Here we report the adsorption of bifunctional 1,4-phenylene diisocyanide (PDI) on the Ge(100)-2 × 1 surface, in which singly bound adsorbates are selectively produced. As shown by polarized multiple internal reflection infrared spectroscopy experiments and density functional theory calculations, PDI adsorbates form a single C-dative bonding configuration through one of the isocyanide functionalities, retaining one unreacted isocyanide moiety per adsorbate. The angle of the molecular axis is ∼30° from the surface normal. The delocalized π* molecular orbital of the free molecule is also preserved upon adsorption. These results demonstrate the potential usefulness of isocyanide adsorbates as a means toward selective organic functionalization of semiconductor surfaces. PMID:26262866

  2. Integrating NiCo Alloys with Their Oxides as Efficient Bifunctional Cathode Catalysts for Rechargeable Zinc-Air Batteries.

    PubMed

    Liu, Xien; Park, Minjoon; Kim, Min Gyu; Gupta, Shiva; Wu, Gang; Cho, Jaephil

    2015-08-10

    The lack of high-efficient, low-cost, and durable bifunctional electrocatalysts that act simultaneously for the oxygen reduction reaction (ORR) and the oxygen evolution reaction (OER) is currently one of the major obstacles to commercializing the electrical rechargeability of zinc-air batteries. A nanocomposite CoO-NiO-NiCo bifunctional electrocatalyst supported by nitrogen-doped multiwall carbon nanotubes (NCNT/CoO-NiO-NiCo) exhibits excellent activity and stability for the ORR/OER in alkaline media. More importantly, real air cathodes made from the bifunctional NCNT/CoO-NiO-NiCo catalysts further demonstrated superior performance to state-of-the-art Pt/C or Pt/C+IrO2 catalysts in primary and rechargeable zinc-air batteries. PMID:26118973

  3. Nanostructured Perovskite LaCo1-xMnxO3 as Bifunctional Catalysts for Rechargeable Metal-Air Batteries

    NASA Astrophysics Data System (ADS)

    Ge, Xiaoming; Li, Bing; Wuu, Delvin; Sumboja, Afriyanti; An, Tao; Hor, T. S. Andy; Zong, Yun; Liu, Zhaolin

    2015-09-01

    Bifunctional catalyst that is active for both oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) is one of the most important components of rechargeable metal-air batteries. Nanostructured perovskite bifunctional catalysts comprising La, Co and Mn(LaCo1-xMnxO3, LCMO) are synthesized by hydrothermal methods. The morphology, structure and electrochemical activity of the perovskite bifunctional catalysts are characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD) and rotating disk electrode (RDE) techniques. Nanorod, nanodisc and nanoparticle are typical morphologies of LCMO. The electrocatalytic activity of LCMO is significantly improved by the addition of conductive materials such as carbon nanotube. To demonstrate the practical utilization, LCMO in the composition of LaCo0.8Mn0.2O3(LCMO82) is used as air cathode catalysts for rechargeable zinc-air batteries. The battery prototype can sustain 470 h or 40 discharge-charge cycles equivalent.

  4. 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.

  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. Enhanced tumor retention of radioiodinated anti-epidermal growth factor receptor antibody using novel bifunctional iodination linker for radioimmunotherapy.

    PubMed

    Kim, Eun Jung; Kim, Byoung Soo; Choi, Dan Bee; Chi, Sung-Gil; Choi, Tae Hyun

    2016-06-01

    Radioimmunotherapy (RIT) uses an antibody labeled with a radionuclide to deliver cytotoxic radiation to a target tumor cells. Radioiodine is most commonly employed to prepare radiolabeled proteins (antibodies, peptides) for in vitro and in vivo applications. A major shortcoming of radioiodinated proteins prepared by direct labeling methods is their deiodination in vivo. For the preparation of more stable radioiodinated antibodies, we developed a new linker (N-(4-isothiocyanatobenzyl)-2-(3-(tributylstannyl)phenyl) acetamide (IBPA). This study evaluated the usefulness of IBPA as a linker for the stable radioiodinated internalizing antibody, cetuximab. Directly labeled cetuximab ([125I]-cetuximab) was prepared by the chloramine T method. To prepare indirectly labeled cetuximab using IBPA ([125I]-IBPA-cetuximab), IBPA was radioiodinated using chloramine-T to give N-(4-isothiocyanatobenzyl)-2-(3-[125I]phenyl)acetamide ([125I]‑IBPA), which was purified by high performance liquid chromatography. [125I]-IBPA was then conjugated to cetuximab. In vitro target binding and internalizing assays were performed in PC9, LS174T, and FaDu cell lines. In vivo planar images were obtained using an Inveon SPECT scanner 3, 24, 48, and 168 h after i.v. injection of [125I]-cetuximab or [125I]-IBPA-cetuximab in athymic mice bearing LS174T tumor xenografts. Specific binding and internalized radioactivity of [125I]-IBPA-cetuximab were higher than those of [125I]-cetuximab in PC9, LS174T, and FaDu cell lines. In planar images scant radioactivity was evident in thyroid glands after injection of [125I]-IBPA-cetuximab, while a high level of radioactivity was present in thyroid glands after injection of [125I]-cetuximab. Tumor uptake value of [125I]-IBPA-cetuximab was higher than that of [125I]-cetuximab for up to 168 h. [125I]-IBPA-cetuximab is stable and resistant to deiodination in vivo. IBPA is a promising bi-functional linker for radioiodination of internalizing monoclonal antibodies

  7. Enhanced tumor retention of radioiodinated anti-epidermal growth factor receptor antibody using novel bifunctional iodination linker for radioimmunotherapy

    PubMed Central

    KIM, EUN JUNG; KIM, BYOUNG SOO; CHOI, DAN BEE; CHI, SUNG-GIL; CHOI, TAE HYUN

    2016-01-01

    Radioimmunotherapy (RIT) uses an antibody labeled with a radionuclide to deliver cytotoxic radiation to a target tumor cells. Radioiodine is most commonly employed to prepare radiolabeled proteins (antibodies, peptides) for in vitro and in vivo applications. A major shortcoming of radioiodinated proteins prepared by direct labeling methods is their deiodination in vivo. For the preparation of more stable radioiodinated antibodies, we developed a new linker (N-(4-isothiocyanatobenzyl)-2-(3-(tributylstannyl)phenyl) acetamide (IBPA). This study evaluated the usefulness of IBPA as a linker for the stable radioiodinated internalizing antibody, cetuximab. Directly labeled cetuximab ([125I]-cetuximab) was prepared by the chloramine T method. To prepare indirectly labeled cetuximab using IBPA ([125I]-IBPA-cetuximab), IBPA was radioiodinated using chloramine-T to give N-(4-isothiocyanatobenzyl)-2-(3-[125I]phenyl)acetamide ([125I]-IBPA), which was purified by high performance liquid chromatography. [125I]-IBPA was then conjugated to cetuximab. In vitro target binding and internalizing assays were performed in PC9, LS174T, and FaDu cell lines. In vivo planar images were obtained using an Inveon SPECT scanner 3, 24, 48, and 168 h after i.v. injection of [125I]-cetuximab or [125I]-IBPA-cetuximab in athymic mice bearing LS174T tumor xenografts. Specific binding and internalized radioactivity of [125I]-IBPA-cetuximab were higher than those of [125I]-cetuximab in PC9, LS174T, and FaDu cell lines. In planar images scant radioactivity was evident in thyroid glands after injection of [125I]-IBPA-cetuximab, while a high level of radioactivity was present in thyroid glands after injection of [125I]-cetuximab. Tumor uptake value of [125I]-IBPA-cetuximab was higher than that of [125I]-cetuximab for up to 168 h. [125I]-IBPA-cetuximab is stable and resistant to deiodination in vivo. IBPA is a promising bi-functional linker for radioiodination of internalizing monoclonal antibodies for in

  8. 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.

  9. The polar bear phenomena

    SciTech Connect

    Maw, P.K. ); Lane, M.T.

    1990-02-01

    Results from measuring the thermal profile of polar bear pelts, reflectiveness of the pelts, and total thermal conversion data lead to the conclusion that the pelts from an ultra-efficient thermal diode for solar-thermal conversion. The transfer of the thermal energy from the surface of the fur to the skin where it is absorbed cannot be thermal, and therefore must be radiative. This process must have an efficiency of better than 90:0090 percent to account for measured values. The radiative transfer process is not known at present. To understand it, a detailed knowledge of the microscopic parameters of the pelts must be obtained. This is the current thrust of the polar solar research. If the process can be understood and synthesized,it will provide a major breakthrough in the area of solar-thermal energy conversion.

  10. Introduction to magnetic bearings

    NASA Astrophysics Data System (ADS)

    Skowronski, Lori; Bisese, Anne

    1993-04-01

    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.

  11. 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.

  12. Ecological effects of contaminants and remedial actions in Bear Creek

    SciTech Connect

    Southworth, G.R.; Loar, J.M.; Ryon, M.G.; Smith, J.G.; Stewart, A.J. ); Burris, J.A. )

    1992-01-01

    Ecological studies of the Bear Creek watershed, which drains the area surrounding several Oak Ridge Y-12 Plant waste disposal facilities, were initiated in May 1984 and are continuing at present. These studies consisted of an initial, detailed characterization of the benthic invertebrate and fish communities in Bear Creek, and they were followed by a presently ongoing monitoring phase that involves reduced sampling intensities. The characterization phase utilized two approaches: (1) instream sampling of benthic invertebrate and fish communities in Bear Creek to identify spatial and temporal patterns in distribution and abundance and (2) laboratory bioassays on water samples from Bear Creek and selected tributaries to identify potential sources of toxicity to biota. The monitoring phase of the ecological program relates to the long-term goals of identifying and prioritizing contaminant sources and assessing the effectiveness of remedial actions. It continues activities of the characterization phase at less frequent intervals. The Bear Greek Valley is a watershed that drains the area surrounding several closed Oak Ridge Y-12 Plant waste disposal facilities. Past waste disposal practices in Bear Creek Valley resulted in contamination of Bear Creek and consequent ecological damage. Extensive remedial actions have been proposed at waste sites, and some of the have been implemented or are now underway. The proposed study plan consists of an initial, detailed characterization of the benthic invertebrate and fish communities in Bear Creek in the first year followed by a reduction in sampling intensity during the monitoring phase of the plan. The results of sampling conducted from May 1984 through early 1989 are presented in this report.

  13. Characterization of modular bifunctional processive endoglucanase Cel5 from Hahella chejuensis KCTC 2396.

    PubMed

    Ghatge, Sunil Subhash; Telke, Amar Anandrao; Kang, Seo-Hee; Arulalapperumal, Venkatesh; Lee, Keun-Woo; Govindwar, Sanjay Prabhu; Um, Youngsoon; Oh, Doo-Byoung; Shin, Hyun-Dong; Kim, Seon-Won

    2014-05-01

    Cel5 from marine Hahella chejuensis is composed of glycoside hydrolase family-5 (GH5) catalytic domain (CD) and two carbohydrate binding modules (CBM6-2). The enzyme was expressed in Escherichia coli and purified to homogeneity. The optimum endoglucanase and xylanase activities of recombinant Cel5 were observed at 65 °C, pH 6.5 and 55 °C, pH 5.5, respectively. It exhibited K m of 1.8 and 7.1 mg/ml for carboxymethyl cellulose and birchwood xylan, respectively. The addition of Ca(2+) greatly improved thermostability and endoglucanase activity of Cel5. The Cel5 retained 90 % of its endoglucanase activity after 24 h incubation in presence of 5 M concentration of NaCl. Recombinant Cel5 showed production of cellobiose after hydrolysis of cellulosic substrates (soluble/insoluble) and methylglucuronic acid substituted xylooligosaccharides after hydrolysis of glucuronoxylans by endo-wise cleavage. These results indicated that Cel5 as bifunctional enzyme having both processive endoglucanase and xylanase activities. The multidomain structure of Cel5 is clearly distinguished from the GH5 bifunctional glycoside hydrolases characterized to date, which are single domain enzymes. Sequence analysis and homology modeling suggested presence of two conserved binding sites with different substrate specificities in CBM6-2 and a single catalytic site in CD. Residues Glu132 and Glu219 were identified as key catalytic amino acids by sequence alignment and further verified by using site directed mutagenesis. CBM6-2 plays vital role in catalytic activity and thermostability of Cel5. The bifunctional activities and multiple substrate specificities of Cel5 can be utilized for efficient hydrolysis of cellulose and hemicellulose into soluble sugars. PMID:24343767

  14. Mechanical characterization of a bifunctional Tetronic hydrogel adhesive for soft tissues.

    PubMed

    Sanders, Lindsey; Stone, Roland; Webb, Kenneth; Mefford, Thompson; Nagatomi, Jiro

    2015-03-01

    Although a number of tissue adhesives and sealants for surgical use are currently available, attaining a useful balance in high strength, high compliance, and low swelling has proven difficult. Recent studies have demonstrated that a four-arm poly(propylene oxide)-poly(ethylene oxide) block copolymer, Tetronic, can be chemically modified to form a hydrogel tissue adhesive (Cho et al., Acta Biomater 2012;8:2223-2232; Barrett et al., Adv Health Mater 2012;1-11; Balakrishnan, Evaluating mechanical performance of hydrogel-based adhesives for soft tissue applications. Clemson University, All Theses, Paper 1574: Tiger Prints; 2013). Building on the success of these studies, this study explored bifunctionalization of Tetronic with acrylates for chemical crosslinking of the hydrogel and N-hydroxysuccinimide (NHS) for reaction with tissue amines. The adhesive bond strengths of various uni and bifunctional Tetronic blends (T1107 ACR: T1107 ACR/NHS) determined by lap shear testing ranged between 8 and 74 kPa, with the 75:25 (T1107 ACR: T1107 ACR/NHS) blend displaying the highest value. These results indicated that addition of NHS led to improvement of tissue bond strength over acrylation alone. Furthermore, ex vivo pressure tests using the rat bladder demonstrated that the bifunctional Tetronic adhesive exhibited high compliance and maintained pressures under hundreds of filling and emptying cycles. Together, the results of this study provided evidence that the bifunctional Tetronic adhesive with a proper blend ratio may be used to achieve an accurate balance in bulk and tissue bond strengths, as well as the compliance and durability for soft tissue such as the bladder. PMID:25111445

  15. Supported bifunctional thioureas as recoverable and reusable catalysts for enantioselective nitro-Michael reactions

    PubMed Central

    Ceballos, Miriam; Maestro, Alicia; Sanz, Isabel

    2016-01-01

    Summary The catalytic activity of different supported bifunctional thioureas on sulfonylpolystyrene resins has been studied in the nitro-Michael addition of different nucleophiles to trans-β-nitrostyrene derivatives. The activity of the catalysts depends on the length of the tether linking the chiral thiourea to the polymer. The best results were obtained with the thiourea derived from (L)-valine and 1,6-hexanediamine. The catalysts can be used in only 2 mol % loading, and reused for at least four cycles in neat conditions. The ball milling promoted additions also worked very well. PMID:27340453

  16. Direct transformation of esters into arenes with 1,5-bifunctional organomagnesium reagents.

    PubMed

    Link, Achim; Fischer, Christian; Sparr, Christof

    2015-10-01

    A direct transformation of carboxylic acid esters into arenes with 1,5-bifunctional organomagnesium reagents is described. This efficient and practical method enables the one-step defunctionalization of various carboxylic acid esters to prepare benzene, anthracene, tetracene, and pentacene derivatives. A double nucleophilic addition of the 1,5-organodimagnesium reagent to the ester is followed by an immediate 1,4-elimination reaction that leads to the direct [5+1] formation of a new aromatic ring. PMID:26291060

  17. A novel bifunctional mitochondria-targeted anticancer agent with high selectivity for cancer cells.

    PubMed

    He, Huan; Li, Dong-Wei; Yang, Li-Yun; Fu, Li; Zhu, Xun-Jin; Wong, Wai-Kwok; Jiang, Feng-Lei; Liu, Yi

    2015-01-01

    Mitochondria have recently emerged as novel targets for cancer therapy due to its important roles in fundamental cellular function. Discovery of new chemotherapeutic agents that allow for simultaneous treatment and visualization of cancer is urgent. Herein, we demonstrate a novel bifunctional mitochondria-targeted anticancer agent (FPB), exhibiting both imaging capability and anticancer activity. It can selectively accumulate in mitochondria and induce cell apoptosis. Notably, it results in much higher toxicity toward cancer cells owing to much higher uptake by cancer cells. These features make it highly attractive in cancer imaging and treatment. PMID:26337336

  18. Acid–base bifunctional shell cross-linked micelle nanoreactor for one-pot tandem reaction

    SciTech Connect

    Lee, Li -Chen; Lu, Jie; Weck, Marcus; Jones, Christopher W.

    2015-12-29

    Shell cross-linked micelles (SCMs) containing acid sites in the shell and base sites in the core are prepared from amphiphilic poly(2-oxazoline) triblock copolymers. The materials are utilized as two-chamber nanoreactors for a prototypical acid-base bifunctional tandem deacetalization-nitroaldol reaction. Furthermore, the acid and base sites are localized in different regions of the micelle, allowing the two steps in the reaction sequence to largely proceed in separate compartments, akin to the compartmentalization that occurs in biological systems.

  19. An efficient bifunctional electrocatalyst for water splitting based on cobalt phosphide

    NASA Astrophysics Data System (ADS)

    Yang, Libin; Qi, Honglan; Zhang, Chengxiao; Sun, Xuping

    2016-06-01

    The development of highly efficient electrocatalysts for water splitting is critical for various renewable-energy technologies. In this letter, we demonstrate a cobalt phosphide nanowire array grown on a Ti mesh (CoP/TM) behaving as a bifunctional electrocatalyst for water splitting. The CoP/TM electrode delivers 10 mA cm‑2 at an overpotential of 72 mV for the hydrogen evolution reaction (HER) and 310 mV for the oxygen evolution reaction (OER) in 1.0 M KOH. Furthermore, its corresponding two-electrode alkaline electrolyzer displays 10 mA cm‑2 at 1.64 V.

  20. Bifunctional phase-transfer catalysis in the asymmetric synthesis of biologically active isoindolinones

    PubMed Central

    Di Mola, Antonia; Tiffner, Maximilian; Scorzelli, Francesco; Palombi, Laura; Filosa, Rosanna; De Caprariis, Paolo

    2015-01-01

    Summary New bifunctional chiral ammonium salts were investigated in an asymmetric cascade synthesis of a key building block for a variety of biologically relevant isoindolinones. With this chiral compound in hand, the development of further transformations allowed for the synthesis of diverse derivatives of high pharmaceutical value, such as the Belliotti (S)-PD172938 and arylated analogues with hypnotic sedative activity, obtained in good overall total yield (50%) and high enantiomeric purity (95% ee). The synthetic routes developed herein are particularly convenient in comparison with the current methods available in literature and are particularly promising for large scale applications. PMID:26734105

  1. Au@Cu(II)-MOF: Highly Efficient Bifunctional Heterogeneous Catalyst for Successive Oxidation-Condensation Reactions.

    PubMed

    Wang, Jing-Si; Jin, Fa-Zheng; Ma, Hui-Chao; Li, Xiao-Bo; Liu, Ming-Yang; Kan, Jing-Lan; Chen, Gong-Jun; Dong, Yu-Bin

    2016-07-01

    A new composite Au@Cu(II)-MOF catalyst has been synthesized via solution impregnation and full characterized by HRTEM, SEM-EDS, XRD, gas adsorption-desorption, XPS, and ICP analysis. It has been shown here that the Cu(II)-framework can be a useful platform to stabilize and support gold nanoparticles (Au NPs). The obtained Au@Cu(II)-MOF exhibits a bifunctional catalytic behavior and is able to promote selective aerobic benzyl alcohol oxidation-Knoevenagel condensation in a stepwise way. PMID:27322613

  2. Highly Enantioselective, Intermolecular Hydroamination of Allenyl Esters Catalyzed by Bifunctional Phosphinothioureas

    PubMed Central

    2015-01-01

    Bifunctional phosphinothiourea catalysts have been developed successfully for the highly regio- and enantioselective γ-hydroamination of allenyl and propargyl esters with N-methoxy carbamate nucleophiles to yield α,β-unsaturated γ-amino acid ester products. In the case of propargyl ester substrates, the reaction proceeds through reversible phosphinothiourea-catalyzed isomerization to the corresponding allenyl ester. The high enantioselectivity of the process is attributed to a cooperative conjugate addition of a thiourea-bound carbamate anion to a vinyl phosphonium ion resulting from covalent activation of the allenyl ester substrate. PMID:25496451

  3. Bifunctional Organic Polymeric Catalysts with a Tunable Acid-Base Distance and Framework Flexibility

    NASA Astrophysics Data System (ADS)

    Chen, Huanhui; Wang, Yanan; Wang, Qunlong; Li, Junhui; Yang, Shiqi; Zhu, Zhirong

    2014-09-01

    Acid-base bifunctional organic polymeric catalysts were synthesized with tunable structures. we demonstrated two synthesis approaches for structural fine-tune. In the first case, the framework flexibility was tuned by changing the ratio of rigid blocks to flexible blocks within the polymer framework. In the second case, we precisely adjusted the acid-base distance by distributing basic monomers to be adjacent to acidic monomers, and by changing the chain length of acidic monomers. In a standard test reaction for the aldol condensation of 4-nitrobenzaldehyde with acetone, the catalysts showed good reusability upon recycling and maintained relatively high conversion percentage.

  4. Bifunctional Brønsted Base Catalyzes Direct Asymmetric Aldol Reaction of α-Keto Amides.

    PubMed

    Echave, Haizea; López, Rosa; Palomo, Claudio

    2016-03-01

    The first enantioselective direct cross-aldol reaction of α-keto amides with aldehydes, mediated by a bifunctional ureidopeptide-based Brønsted base catalyst, is described. The appropriate combination of a tertiary amine base and an aminal, and urea hydrogen-bond donor groups in the catalyst structure promoted the exclusive generation of the α-keto amide enolate which reacted with either non-enolizable or enolizable aldehydes to produce highly enantioenriched polyoxygenated aldol adducts without side-products resulting from dehydration, α-keto amide self-condensation, aldehyde enolization, and isotetronic acid formation. PMID:26835655

  5. An efficient bifunctional electrocatalyst for water splitting based on cobalt phosphide.

    PubMed

    Yang, Libin; Qi, Honglan; Zhang, Chengxiao; Sun, Xuping

    2016-06-10

    The development of highly efficient electrocatalysts for water splitting is critical for various renewable-energy technologies. In this letter, we demonstrate a cobalt phosphide nanowire array grown on a Ti mesh (CoP/TM) behaving as a bifunctional electrocatalyst for water splitting. The CoP/TM electrode delivers 10 mA cm(-2) at an overpotential of 72 mV for the hydrogen evolution reaction (HER) and 310 mV for the oxygen evolution reaction (OER) in 1.0 M KOH. Furthermore, its corresponding two-electrode alkaline electrolyzer displays 10 mA cm(-2) at 1.64 V. PMID:27146428

  6. A novel bifunctional mitochondria-targeted anticancer agent with high selectivity for cancer cells

    PubMed Central

    He, Huan; Li, Dong-Wei; Yang, Li-Yun; Fu, Li; Zhu, Xun-Jin; Wong, Wai-Kwok; Jiang, Feng-Lei; Liu, Yi

    2015-01-01

    Mitochondria have recently emerged as novel targets for cancer therapy due to its important roles in fundamental cellular function. Discovery of new chemotherapeutic agents that allow for simultaneous treatment and visualization of cancer is urgent. Herein, we demonstrate a novel bifunctional mitochondria-targeted anticancer agent (FPB), exhibiting both imaging capability and anticancer activity. It can selectively accumulate in mitochondria and induce cell apoptosis. Notably, it results in much higher toxicity toward cancer cells owing to much higher uptake by cancer cells. These features make it highly attractive in cancer imaging and treatment. PMID:26337336

  7. Bifunctional phase-transfer catalysis in the asymmetric synthesis of biologically active isoindolinones.

    PubMed

    Di Mola, Antonia; Tiffner, Maximilian; Scorzelli, Francesco; Palombi, Laura; Filosa, Rosanna; De Caprariis, Paolo; Waser, Mario; Massa, Antonio

    2015-01-01

    New bifunctional chiral ammonium salts were investigated in an asymmetric cascade synthesis of a key building block for a variety of biologically relevant isoindolinones. With this chiral compound in hand, the development of further transformations allowed for the synthesis of diverse derivatives of high pharmaceutical value, such as the Belliotti (S)-PD172938 and arylated analogues with hypnotic sedative activity, obtained in good overall total yield (50%) and high enantiomeric purity (95% ee). The synthetic routes developed herein are particularly convenient in comparison with the current methods available in literature and are particularly promising for large scale applications. PMID:26734105

  8. Tunable catalytic properties of bi-functional mixed oxides in ethanol conversion to high value compounds

    DOE PAGESBeta

    Ramasamy, Karthikeyan K.; Gray, Michel; Job, Heather; Smith, Colin; Wang, Yong

    2016-02-03

    Here, a highly versatile ethanol conversion process to selectively generate high value compounds is presented here. By changing the reaction temperature, ethanol can be selectively converted to >C2 alcohols/oxygenates or phenolic compounds over hydrotalcite derived bi-functional MgO–Al2O3 catalyst via complex cascade mechanism. Reaction temperature plays a role in whether aldol condensation or the acetone formation is the path taken in changing the product composition. This article contains the catalytic activity comparison between the mono-functional and physical mixture counterpart to the hydrotalcite derived mixed oxides and the detailed discussion on the reaction mechanisms.

  9. Recovery of uranium from acid media by macroporous bifunctional phosphinic acid resin

    SciTech Connect

    Sabharwal, K.N.; Srinivasan, T.G.; Rao, P.R.V.; Nandy, K.K.

    1996-11-01

    The extraction of uranium from various acid media such as nitric acid, sulphuric acid, hydrochloric acid, phosphoric acid and perchloric acid by a macroporous bifunctional phosphinic acid resin (MPBPA) has been studied. The distribution coefficients for the extraction of uranium by the MPBPA resin are compared with the corresponding values reported in literature for the conventional sulphonic acid resin. The results clearly indicate the suitability of the MPBPA resin to recover uranium from different types of acid solutions of widely ranging acidities. 17 refs., 6 figs., 5 tabs.

  10. 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 ΔE (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 ΔE (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

  11. NiCoMnO4: A Bifunctional Affinity Probe for His-Tagged Protein Purification and Phosphorylation Sites Recognition.

    PubMed

    Qi, Xiaoyue; Chen, Long; Zhang, Chaoqun; Xu, Xinyuan; Zhang, Yiding; Bai, Yu; Liu, Huwei

    2016-07-27

    A bifunctional affinity probe NiCoMnO4 was designed and prepared with controllable morphology and size using facile methods. It was observed that the probe could be applied in His-tagged proteins purification and phosphopeptides enrichment simply through the buffer modulation. NiCoMnO4 particles showed satisfactory cycling performance for His-tagged proteins purification and broad pH-tolerance of loading buffer for phosphopeptides affinity. Therefore, a high-throughput, cost-effective, and efficient protein/peptide purification method was developed within 10 min based on the novel bifunctional affinity probe. PMID:27381638

  12. 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.

  13. Lubrication of rolling element bearings

    NASA Technical Reports Server (NTRS)

    Parker, R. J.

    1980-01-01

    This paper is a broad survey of the lubrication of rolling-element bearings. Emphasis is on the critical design aspects related to speed, temperature, and ambient pressure environment. Types of lubrication including grease, jets, mist, wick, and through-the-race are discussed. The paper covers the historical development, present state of technology, and the future problems of rolling-element bearing lubrication.

  14. Permanent-Magnet Meissner Bearing

    NASA Technical Reports Server (NTRS)

    Robertson, Glen A.

    1994-01-01

    Permanent-magnet meissner bearing features inherently stable, self-centering conical configuration. Bearing made stiffer or less stiff by selection of magnets, springs, and spring adjustments. Cylindrical permanent magnets with axial magnetization stacked coaxially on rotor with alternating polarity. Typically, rare-earth magnets used. Magnets machined and fitted together to form conical outer surface.

  15. Nonlinear control of magnetic bearings

    NASA Technical Reports Server (NTRS)

    Pradeep, A. K.; Gurumoorthy, R.

    1994-01-01

    In this paper we present a variety of nonlinear controllers for the magnetic bearing that ensure both stability and robustness. We utilize techniques of discontinuous control to design novel control laws for the magnetic bearing. We present in particular sliding mode controllers, time optimal controllers, winding algorithm based controllers, nested switching controllers, fractional controllers, and synchronous switching controllers for the magnetic bearing. We show existence of solutions to systems governed by discontinuous control laws, and prove stability and robustness of the chosen control laws in a rigorous setting. We design sliding mode observers for the magnetic bearing and prove the convergence of the state estimates to their true values. We present simulation results of the performance of the magnetic bearing subject to the aforementioned control laws, and conclude with comments on design.

  16. Space Station alpha joint bearing

    NASA Technical Reports Server (NTRS)

    Everman, Michael R.; Jones, P. Alan; Spencer, Porter A.

    1987-01-01

    Perhaps the most critical structural system aboard the Space Station is the Solar Alpha Rotary Joint which helps align the power generation system with the sun. The joint must provide structural support and controlled rotation to the outboard transverse booms as well as power and data transfer across the joint. The Solar Alpha Rotary Joint is composed of two transition sections and an integral, large diameter bearing. Alpha joint bearing design presents a particularly interesting problem because of its large size and need for high reliability, stiffness, and on orbit maintability. The discrete roller bearing developed is a novel refinement to cam follower technology. It offers thermal compensation and ease of on-orbit maintenance that are not found in conventional rolling element bearings. How the bearing design evolved is summarized. Driving requirements are reviewed, alternative concepts assessed, and the selected design is described.

  17. Geophagy by yellowstone grizzly bears

    USGS Publications Warehouse

    Mattson, D.J.; Green, G.I.; Swalley, R.

    1999-01-01

    We documented 12 sites in the Yellowstone ecosystem where grizzly bears (Ursus arctos horribilis) had purposefully consumed soil (an activity known as geophagy). We also documented soil in numerous grizzly bear feces. Geophagy primarily occurred at sites barren of vegetation where surficial geology had been modified by geothermal activity. There was no evidence of ungulate use at most sites. Purposeful consumption of soil by bears peaked first from March to May and again from August to October, synchronous with peaks in consumption of ungulate meat and mushrooms. Geophageous soils were distinguished from ungulate mineral licks and soils in general by exceptionally high concentrations of potassium (K) and high concentrations of magnesium (Mg) and sulphur (S). Our results do not support the hypotheses that bears were consuming soil to detoxify secondary compounds in grazed foliage, as postulated for primates, or to supplement dietary sodium, as known for ungulates. Our results suggest that grizzly bears could have been consuming soil as an anti-diarrheal.

  18. Acquired arteriovenous fistula in a grizzly bear (Ursus arctos horribilis).

    PubMed

    Tuttle, Allison D; MacLean, Robert A; Linder, Keith; Cullen, John M; Wolfe, Barbara A; Loomis, Michael

    2009-03-01

    A captive adult male grizzly bear (Ursus arctos horribilis) was evaluated due to multifocal wounds of the skin and subcutaneous tissues sustained as a result of trauma from another grizzly bear. On presentation, one lesion that was located in the perineal region seemed to be a deep puncture with purple tissue protruding from it. This perineal wound did not heal in the same manner or rate as did the other wounds. Twenty-five days after initial detection, substantial active hemorrhage from the lesion occurred and necessitated anesthesia for examination of the bear. The entire lesion was surgically excised, which later proved curative. An acquired arteriovenous fistula was diagnosed via histopathology. Arteriovenous fistulas can develop after traumatic injury and should be considered as a potential complication in bears with nonhealing wounds. PMID:19368261

  19. Effects of bearing cleaning and lube environment on bearing performance

    NASA Technical Reports Server (NTRS)

    Ward, Peter C.

    1995-01-01

    Running torque data of SR6 ball bearings are presented for different temperatures and speeds. The data are discussed in contrast to generally used torque prediction models and point out the need to obtain empirical data in critical applications. Also, the effects of changing bearing washing techniques from old, universally used CFC-based systems to CFC-free aqueous/alkaline solutions are discussed. Data on wettability, torque and lubricant life using SR3 ball bearings are presented. In general, performance is improved using the new aqueous washing techniques.

  20. Characteristics of bifunctional acidic endoglucanase (Cel5B) from Gloeophyllum trabeum.

    PubMed

    Kim, Ho Myeong; Lee, Yoon Gyo; Patel, Darshan H; Lee, Kwang Ho; Lee, Dae-Seok; Bae, Hyeun-Jong

    2012-07-01

    The endoglucanase (Cel5B) from the filamentous fungus Gloeophyllum trabeum was cloned and expressed without a signal peptide, and alanine residue 22 converted to glutamine in Pichia pastoris GS115. The DNA sequence of Cel5B had an open reading frame of 1,077 bp, encoding a protein of 359 amino acid residues with a molecular weight of 47 kDa. On the basis of sequence similarity, Cel5B displayed active site residues at Glu-175 and Glu-287. Both residues lost full hydrolytic activity when replaced with alanine through point mutation. The purified recombinant Cel5B showed very high specific activity, about 80- to 1,000-fold and 13- to 70-fold in comparison with other endoglucanases and cellobiohydrolase, on carboxymethylcellulose and filter paper, respectively, at pH 3.5 and 55°C. Cel5B displayed bifunctional characteristics under acidic conditions. The kinetic properties of the enzyme determined using a Lineweaver-Burk plot indicated that Cel5B is a catalytically efficient cellulolytic enzyme. These results suggest that Cel5B has high bifunctional endo- and exoglucanase activity under acidic conditions and is a good candidate for bioconversion of lignocellulose. PMID:22395898

  1. A bifunctional spin label reports the structural topology of phospholamban in magnetically-aligned bicelles.

    PubMed

    McCaffrey, Jesse E; James, Zachary M; Svensson, Bengt; Binder, Benjamin P; Thomas, David D

    2016-01-01

    We have applied a bifunctional spin label and EPR spectroscopy to determine membrane protein structural topology in magnetically-aligned bicelles, using monomeric phospholamban (PLB) as a model system. Bicelles are a powerful tool for studying membrane proteins by NMR and EPR spectroscopies, where magnetic alignment yields topological constraints by resolving the anisotropic spectral properties of nuclear and electron spins. However, EPR bicelle studies are often hindered by the rotational mobility of monofunctional Cys-linked spin labels, which obscures their orientation relative to the protein backbone. The rigid and stereospecific TOAC label provides high orientational sensitivity but must be introduced via solid-phase peptide synthesis, precluding its use in large proteins. Here we show that a bifunctional methanethiosulfonate spin label attaches rigidly and stereospecifically to Cys residues at i and i+4 positions along PLB's transmembrane helix, thus providing orientational resolution similar to that of TOAC, while being applicable to larger membrane proteins for which synthesis is impractical. Computational modeling and comparison with NMR data shows that these EPR experiments provide accurate information about helix tilt relative to the membrane normal, thus establishing a robust method for determining structural topology in large membrane proteins with a substantial advantage in sensitivity over NMR. PMID:26720587

  2. Bifunctional Spin Labeling of Muscle Proteins: Accurate Rotational Dynamics, Orientation, and Distance by EPR.

    PubMed

    Thompson, Andrew R; Binder, Benjamin P; McCaffrey, Jesse E; Svensson, Bengt; Thomas, David D

    2015-01-01

    While EPR allows for the characterization of protein structure and function due to its exquisite sensitivity to spin label dynamics, orientation, and distance, these measurements are often limited in sensitivity due to the use of labels that are attached via flexible monofunctional bonds, incurring additional disorder and nanosecond dynamics. In this chapter, we present methods for using a bifunctional spin label (BSL) to measure muscle protein structure and dynamics. We demonstrate that bifunctional attachment eliminates nanosecond internal rotation of the spin label, thereby allowing the accurate measurement of protein backbone rotational dynamics, including microsecond-to-millisecond motions by saturation transfer EPR. BSL also allows for accurate determination of helix orientation and disorder in mechanically and magnetically aligned systems, due to the label's stereospecific attachment. Similarly, labeling with a pair of BSL greatly enhances the resolution and accuracy of distance measurements measured by double electron-electron resonance (DEER). Finally, when BSL is applied to a protein with high helical content in an assembly with high orientational order (e.g., muscle fiber or membrane), two-probe DEER experiments can be combined with single-probe EPR experiments on an oriented sample in a process we call BEER, which has the potential for ab initio high-resolution structure determination. PMID:26477249

  3. Bifunctional catalysis of the dedeuteration of methoxyacetone-1,1,3,3,3-d

    SciTech Connect

    Hine, J.; Sinha, A.

    1984-06-15

    The dedeuteration of methoxyacetone-1,1,3,3,3-d/sub 5/ is subject to bifunctional catalysis by 3-(dimethylamino)-propylamine (3DP) and (1R,2S,3R,4R)-3-((dimethylamino)methyl)-1,7,7-trimethyl-2-norbornamine (DTN). These catalysts act by using their primary amino groups to transform the ketone to an iminium ion and their tertiary amino groups to transfer a deuteron internally, changing the iminium ion to an enamine. Although analogous monofunctional bases favor exchange at the methyl position relative to exchange at the methylene position by factors of up to 4-fold, bifunctional catalysis by the diamines used favors the methyl group by 11- to 15-fold. Exchange at the methylene group in the presence of DTN was strongly stereoselective. The pro-S deuteron was removed 12-20 times as rapidly as the pro-R deuteron. This is the result of the steric effect of the methoxy substituent. 19 references, 2 figures, 2 tables.

  4. Bifunctional Ag/C3N4.5 composite nanobelts for photocatalysis and antibacterium.

    PubMed

    Lei, Renbo; Jian, Jikang; Zhang, Zhihua; Song, Bo; Wu, Rong

    2016-09-30

    Multiple functions can be achieved in carbon nitride-based composite nanomaterials by tuning their components and structures. Here, we report on a large-scale synthesis of novel bifunctional Ag/C3N4.5 composite nanobelts (CNBs) with efficient photocatalytic and antibacterial activity. The Ag/C3N4.5 CNBs were synthesized in high yield by a two-step route including a homogeneous precipitation process and a subsequent calcination treatment. The structural, morphological, compositional, and spectroscopic characterizations revealed that the Ag/C3N4.5 CNBs are composed of N-deficient melem ultrathin nanobelts and crystalline Ag nanoparticles attached to the surface of the nanobelts with good contact. The band gap of the Ag/C3N4.5 CNBs is determined to be about 3.04 eV. The efficient photocatalytic and antibacterial activities of the composite nanomaterials are verified by testing the degradation of Rhodamine B (RhB) and the inhibition zone to bacterium E. coli. The work provides a facile route to bifunctional carbon nitride-based composites with potential applications in the fields of the environment and biology. PMID:27560165

  5. Bifunctional graphene/γ-Fe₂O₃ hybrid aerogels with double nanocrystalline networks for enzyme immobilization.

    PubMed

    Chen, Liang; Wei, Bin; Zhang, Xuetong; Li, Chun

    2013-07-01

    Highly porous hosting materials with conducting (favorable to electron transfer) and magnetic (favorable to product separation) bicontinuous networks should possess great potentials for immobilization of various enzymes in the field of biocatalytic engineering, but the synthesis of such materials is still a great challenge. Herein, bifunctional graphene/γ-Fe2 O3 hybrid aerogels with quite low density (30-65 mg cm(-3) ), large specific surface area (270-414 m(2) g(-1) ), high electrical conductivity (0.5-5 × 10(-2) S m(-1) ), and superior saturation magnetization (23-54 emu g(-1) ) are fabricated. Single networks of either graphene aerogels or γ-Fe2 O3 aerogels are obtained by etching of the hybrid aerogels with acid solution or calcining of the hybrid aerogels in air, indicative of the double networks of the as-synthesized graphene/γ-Fe2 O3 hybrid aerogels for the first time. The resulting bifunctional aerogels are used to immobilize β-glucuronidase for biocatalytic transformation of glycyrrhizin into glycyrrhetinic acid monoglucuronide or glycyrrhetinic acid, with high biocatalytic activity and definite repeatability. PMID:23423944

  6. Binuclear platinum (II)-terpyridine complexes. A new class of bifunctional DNA-intercalating agent.

    PubMed Central

    McFadyen, W D; Wakelin, L P; Roos, I A; Hillcoat, B L

    1986-01-01

    A series of binuclear DNA-binding ligands was prepared by linking two (2,2':6',2"-terpyridine)platinum(II) moieties via alpha omega-dithiols of the type HS-[CH2]n-SH where n = 4-10. A monomeric analogue was also synthesized. Compounds were characterized by elemental analysis and electronic and n.m.r. spectroscopy. Viscometric measurements with sonicated rod-like DNA fragments and covalently closed circular DNA were performed to investigate the mode of binding of these agents. The ligands with n = 5 and 6 function as bis intercalators and form a single 'base-pair sandwich' in violation of neighbour-exclusion binding. Bifunctional reaction occurs for the ligand with n = 7, whereas the ligands with n = 8 and 10 show a preference for mixed monofunctional/bifunctional binding. The data do not permit definitive assignment of the binding mode of the ligands with n = 4 and 9. All compounds are growth-inhibitory against mouse leukaemia L1210 cells in culture with IC50 values in the range 2-14 microM. PMID:3800959

  7. Magnetically labelled gold and epoxy bi-functional microcarriers for suspension based bioassay technologies.

    PubMed

    Vyas, Kunal N; Palfreyman, Justin J; Love, David M; Mitrelias, Thanos; Barnes, Crispin H W

    2012-12-21

    Microarrays and suspension-based assay technologies have attracted significant interest over the past decade with applications ranging from medical diagnostics to high throughput molecular biology. The throughput and sensitivity of a microarray will always be limited by the array density and slow reaction kinetics. Suspension (or bead) based technologies offer a conceptually different approach, improving detection by substituting a fixed plane of operation with many individually distinguishable microcarriers. In addition to all the features of a suspension based assay technology, our technology offers a rewritable label. This has the potential to be truly revolutionary by opening up the possibility of generating, on chip, extensive labelled molecular libraries. We unveil our latest SU-8 microcarrier design with embedded magnetic films that can be utilized for both magnetic and optical labelling. The novel design significantly simplifies fabrication and additionally incorporates a gold cap to provide a dual surface, bi-functional architecture. The microcarriers are fabricated using deep-ultraviolet lithography techniques and metallic thin film growth by evaporation. The bi-functional properties of the microcarriers will allow us to use each microcarrier as its own positive control thereby increasing the reliability of our technology. Here we present details of the design, fabrication, magnetic detection and functionalization of these microcarriers. PMID:23128508

  8. A bifunctional spin label reports the structural topology of phospholamban in magnetically-aligned bicelles

    NASA Astrophysics Data System (ADS)

    McCaffrey, Jesse E.; James, Zachary M.; Svensson, Bengt; Binder, Benjamin P.; Thomas, David D.

    2016-01-01

    We have applied a bifunctional spin label and EPR spectroscopy to determine membrane protein structural topology in magnetically-aligned bicelles, using monomeric phospholamban (PLB) as a model system. Bicelles are a powerful tool for studying membrane proteins by NMR and EPR spectroscopies, where magnetic alignment yields topological constraints by resolving the anisotropic spectral properties of nuclear and electron spins. However, EPR bicelle studies are often hindered by the rotational mobility of monofunctional Cys-linked spin labels, which obscures their orientation relative to the protein backbone. The rigid and stereospecific TOAC label provides high orientational sensitivity but must be introduced via solid-phase peptide synthesis, precluding its use in large proteins. Here we show that a bifunctional methanethiosulfonate spin label attaches rigidly and stereospecifically to Cys residues at i and i + 4 positions along PLB's transmembrane helix, thus providing orientational resolution similar to that of TOAC, while being applicable to larger membrane proteins for which synthesis is impractical. Computational modeling and comparison with NMR data shows that these EPR experiments provide accurate information about helix tilt relative to the membrane normal, thus establishing a robust method for determining structural topology in large membrane proteins with a substantial advantage in sensitivity over NMR.

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

    SciTech Connect

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

    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.

  10. Determining the Origin of Half-bandgap-voltage Electroluminescence in Bifunctional Rubrene/C60 Devices

    PubMed Central

    Chen, Qiusong; Jia, Weiyao; Chen, Lixiang; Yuan, De; Zou, Yue; Xiong, Zuhong

    2016-01-01

    Lowering the driving voltage of organic light-emitting diodes (OLEDs) is an important approach to reduce their energy consumption. We have fabricated a series of bifunctional devices (OLEDs and photovoltaics) using rubrene and fullerene (C60) as the active layer, in which the electroluminescence threshold voltage(~1.1 V) was half the value of the bandgap of rubrene. Magneto-electroluminescence (MEL) response of planner heterojunction diodes exhibited a small increase in response to a low magnetic field strength (<20 mT); however, a very large decay was observed at a high magnetic field strength (>20 mT). When a hole-transport layer with a low mobility was included in these devices, the MEL response reversed in shape, and simultaneously, the EL threshold voltage became larger than the bandgap voltage. When bulk heterojunction device was examined, the amplitude of MEL curves presented an anomalous voltage-dependence. Following an analysis of the MEL responses of these devices, we proposed that the EL of half-bandgap-voltage device originated from bimolecular triplet-triplet annihilation in the rubrene film, rather than from singlet excitons that formed via an interface auger recombination. This work provides critical insight into the mechanisms of OLED emission and will help advance the applications of bifunctional devices. PMID:27142285

  11. 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

  12. Conversion of cellulose into isosorbide over bifunctional ruthenium nanoparticles supported on niobium phosphate.

    PubMed

    Sun, Peng; Long, Xiangdong; He, Hao; Xia, Chungu; Li, Fuwei

    2013-11-01

    Considerable effort has been applied to the development of new processes and catalysts for cellulose conversion to valuable platform chemicals. Isosorbide is among the most interesting products as it can be applied as a monomer and building block for the future replacement of fossil resource-based products. A sustainable method of isosorbide production from cellulose is presented in this work. The strategy relies on a bifunctional Ru catalyst supported on mesoporous niobium phosphate in a H2 atmosphere under pressure without further addition of any soluble acid. Over 50 % yield of isosorbide with almost 100 % cellulose conversion can be obtained in 1 h. The large surface area, pore size, and strong acidity of mesoporous niobium phosphate promote the hydrolysis of cellulose and dehydration of sorbitol; additionally, the appropriate size of the supported Ru nanoparticles avoids unnecessary hydrogenolysis of sorbitol. Under a cellulose/catalyst mass ratio of 43.3, the present bifunctional catalyst could be stably used up to six times, with its mesoporous structure well preserved and without detectable Ru leaching into the reaction solution. PMID:24115374

  13. Bifunctional Ligands for Inhibition of Tight-Binding Protein-Protein Interactions.

    PubMed

    Ivan, Taavi; Enkvist, Erki; Viira, Birgit; Manoharan, Ganesh Babu; Raidaru, Gerda; Pflug, Alexander; Alam, Kazi Asraful; Zaccolo, Manuela; Engh, Richard Alan; Uri, Asko

    2016-08-17

    The acknowledged potential of small-molecule therapeutics targeting disease-related protein-protein interactions (PPIs) has promoted active research in this field. The strategy of using small molecule inhibitors (SMIs) to fight strong (tight-binding) PPIs tends to fall short due to the flat and wide interfaces of PPIs. Here we propose a biligand approach for disruption of strong PPIs. The potential of this approach was realized for disruption of the tight-binding (KD = 100 pM) tetrameric holoenzyme of cAMP-dependent protein kinase (PKA). Supported by X-ray analysis of cocrystals, bifunctional inhibitors (ARC-inhibitors) were constructed that simultaneously associated with both the ATP-pocket and the PPI interface area of the catalytic subunit of PKA (PKAc). Bifunctional inhibitor ARC-1411, possessing a KD value of 3 pM toward PKAc, induced the dissociation of the PKA holoenzyme with a low-nanomolar IC50, whereas the ATP-competitive inhibitor H89 bound to the PKA holoenzyme without disruption of the protein tetramer. PMID:27389935

  14. Highly Efficient and Robust Nickel Phosphides as Bifunctional Electrocatalysts for Overall Water-Splitting.

    PubMed

    Li, Jiayuan; Li, Jing; Zhou, Xuemei; Xia, Zhaoming; Gao, Wei; Ma, Yuanyuan; Qu, Yongquan

    2016-05-01

    To search for the efficient non-noble metal based and/or earth-abundant electrocatalysts for overall water-splitting is critical to promote the clean-energy technologies for hydrogen economy. Herein, we report nickel phosphide (NixPy) catalysts with the controllable phases as the efficient bifunctional catalysts for water electrolysis. The phases of NixPy were determined by the temperatures of the solid-phase reaction between the ultrathin Ni(OH)2 plates and NaH2PO2·H2O. The NixPy with the richest Ni5P4 phase synthesized at 325 °C (NixPy-325) delivered efficient and robust catalytic performance for hydrogen evolution reaction (HER) in the electrolytes with a wide pH range. The NixPy-325 catalysts also exhibited a remarkable performance for oxygen evolution reaction (OER) in a strong alkaline electrolyte (1.0 M KOH) due to the formation of surface NiOOH species. Furthermore, the bifunctional NixPy-325 catalysts enabled a highly performed overall water-splitting with ∼100% Faradaic efficiency in 1.0 M KOH electrolyte, in which a low applied external potential of 1.57 V led to a stabilized catalytic current density of 10 mA/cm(2) over 60 h. PMID:27064172

  15. Active-site remodelling in the bifunctional fructose-1,6-bisphosphate aldolase/phosphatase.

    PubMed

    Du, Juan; Say, Rafael F; Lü, Wei; Fuchs, Georg; Einsle, Oliver

    2011-10-27

    Fructose-1,6-bisphosphate (FBP) aldolase/phosphatase is a bifunctional, thermostable enzyme that catalyses two subsequent steps in gluconeogenesis in most archaea and in deeply branching bacterial lineages. It mediates the aldol condensation of heat-labile dihydroxyacetone phosphate (DHAP) and glyceraldehyde-3-phosphate (GAP) to FBP, as well as the subsequent, irreversible hydrolysis of the product to yield the stable fructose-6-phosphate (F6P) and inorganic phosphate; no reaction intermediates are released. Here we present a series of structural snapshots of the reaction that reveal a substantial remodelling of the active site through the movement of loop regions that create different catalytic functionalities at the same location. We have solved the three-dimensional structures of FBP aldolase/phosphatase from thermophilic Thermoproteus neutrophilus in a ligand-free state as well as in complex with the substrates DHAP and FBP and the product F6P to resolutions up to 1.3 Å. In conjunction with mutagenesis data, this pinpoints the residues required for the two reaction steps and shows that the sequential binding of additional Mg(2+) cations reversibly facilitates the reaction. FBP aldolase/phosphatase is an ancestral gluconeogenic enzyme optimized for high ambient temperatures, and our work resolves how consecutive structural rearrangements reorganize the catalytic centre of the protein to carry out two canonical reactions in a very non-canonical type of bifunctionality. PMID:21983965

  16. Structural basis for the bifunctionality of fructose-1,6-bisphosphate aldolase/phosphatase.

    PubMed

    Fushinobu, Shinya; Nishimasu, Hiroshi; Hattori, Daiki; Song, Hyun-Jin; Wakagi, Takayoshi

    2011-10-27

    Enzymes catalyse specific reactions and are essential for maintaining life. Although some are referred to as being bifunctional, they consist of either two distinct catalytic domains or a single domain that displays promiscuous substrate specificity. Thus, one enzyme active site is generally responsible for one biochemical reaction. In contrast to this conventional concept, archaeal fructose-1,6-bisphosphate (FBP) aldolase/phosphatase (FBPA/P) consists of a single catalytic domain, but catalyses two chemically distinct reactions of gluconeogenesis: (1) the reversible aldol condensation of dihydroxyacetone phosphate (DHAP) and glyceraldehyde-3-phosphate (GA3P) to FBP; (2) the dephosphorylation of FBP to fructose-6-phosphate (F6P). Thus, FBPA/P is fundamentally different from ordinary enzymes whose active sites are responsible for a specific reaction. However, the molecular mechanism by which FBPA/P achieves its unusual bifunctionality remains unknown. Here we report the crystal structure of FBPA/P at 1.5-Å resolution in the aldolase form, where a critical lysine residue forms a Schiff base with DHAP. A structural comparison of the aldolase form with a previously determined phosphatase form revealed a dramatic conformational change in the active site, demonstrating that FBPA/P metamorphoses its active-site architecture to exhibit dual activities. Thus, our findings expand the conventional concept that one enzyme catalyses one biochemical reaction. PMID:21983966

  17. Determining the Origin of Half-bandgap-voltage Electroluminescence in Bifunctional Rubrene/C60 Devices

    NASA Astrophysics Data System (ADS)

    Chen, Qiusong; Jia, Weiyao; Chen, Lixiang; Yuan, De; Zou, Yue; Xiong, Zuhong

    2016-05-01

    Lowering the driving voltage of organic light-emitting diodes (OLEDs) is an important approach to reduce their energy consumption. We have fabricated a series of bifunctional devices (OLEDs and photovoltaics) using rubrene and fullerene (C60) as the active layer, in which the electroluminescence threshold voltage(~1.1 V) was half the value of the bandgap of rubrene. Magneto-electroluminescence (MEL) response of planner heterojunction diodes exhibited a small increase in response to a low magnetic field strength (<20 mT) however, a very large decay was observed at a high magnetic field strength (>20 mT). When a hole-transport layer with a low mobility was included in these devices, the MEL response reversed in shape, and simultaneously, the EL threshold voltage became larger than the bandgap voltage. When bulk heterojunction device was examined, the amplitude of MEL curves presented an anomalous voltage-dependence. Following an analysis of the MEL responses of these devices, we proposed that the EL of half-bandgap-voltage device originated from bimolecular triplet-triplet annihilation in the rubrene film, rather than from singlet excitons that formed via an interface auger recombination. This work provides critical insight into the mechanisms of OLED emission and will help advance the applications of bifunctional devices.

  18. Large-scale Generation of Patterned Bubble Arrays on Printed Bi-functional Boiling Surfaces

    NASA Astrophysics Data System (ADS)

    Choi, Chang-Ho; David, Michele; Gao, Zhongwei; Chang, Alvin; Allen, Marshall; Wang, Hailei; Chang, Chih-Hung

    2016-04-01

    Bubble nucleation control, growth and departure dynamics is important in understanding boiling phenomena and enhancing nucleate boiling heat transfer performance. We report a novel bi-functional heterogeneous surface structure that is capable of tuning bubble nucleation, growth and departure dynamics. For the fabrication of the surface, hydrophobic polymer dot arrays are first printed on a substrate, followed by hydrophilic ZnO nanostructure deposition via microreactor-assisted nanomaterial deposition (MAND) processing. Wettability contrast between the hydrophobic polymer dot arrays and aqueous ZnO solution allows for the fabrication of heterogeneous surfaces with distinct wettability regions. Heterogeneous surfaces with various configurations were fabricated and their bubble dynamics were examined at elevated heat flux, revealing various nucleate boiling phenomena. In particular, aligned and patterned bubbles with a tunable departure frequency and diameter were demonstrated in a boiling experiment for the first time. Taking advantage of our fabrication method, a 6 inch wafer size heterogeneous surface was prepared. Pool boiling experiments were also performed to demonstrate a heat flux enhancement up to 3X at the same surface superheat using bi-functional surfaces, compared to a bare stainless steel surface.

  19. Large-scale Generation of Patterned Bubble Arrays on Printed Bi-functional Boiling Surfaces.

    PubMed

    Choi, Chang-Ho; David, Michele; Gao, Zhongwei; Chang, Alvin; Allen, Marshall; Wang, Hailei; Chang, Chih-hung

    2016-01-01

    Bubble nucleation control, growth and departure dynamics is important in understanding boiling phenomena and enhancing nucleate boiling heat transfer performance. We report a novel bi-functional heterogeneous surface structure that is capable of tuning bubble nucleation, growth and departure dynamics. For the fabrication of the surface, hydrophobic polymer dot arrays are first printed on a substrate, followed by hydrophilic ZnO nanostructure deposition via microreactor-assisted nanomaterial deposition (MAND) processing. Wettability contrast between the hydrophobic polymer dot arrays and aqueous ZnO solution allows for the fabrication of heterogeneous surfaces with distinct wettability regions. Heterogeneous surfaces with various configurations were fabricated and their bubble dynamics were examined at elevated heat flux, revealing various nucleate boiling phenomena. In particular, aligned and patterned bubbles with a tunable departure frequency and diameter were demonstrated in a boiling experiment for the first time. Taking advantage of our fabrication method, a 6 inch wafer size heterogeneous surface was prepared. Pool boiling experiments were also performed to demonstrate a heat flux enhancement up to 3X at the same surface superheat using bi-functional surfaces, compared to a bare stainless steel surface. PMID:27034255

  20. MULT1E/mIL-12: a novel bifunctional protein for natural killer cell activation.

    PubMed

    Tietje, A; Li, J; Yu, X; Wei, Y

    2014-05-01

    Natural killer (NK) cells have the potential to be effective killers of tumor cells. They are governed by inhibitory and activating receptors like NKG2D, whose ligands are normally upregulated in cells that are stressed, like cancer cells. Advanced cancer cells, however, have ways to reduce these ligands' expression, leaving them less detectable by NK cells. Along with these receptors, NK cells also require activating cytokines, like interleukin 12 (IL-12). The goal of this study is to develop a novel bi-functional fusion protein for enhanced NK cell activation. The proposed protein combines the extracellular domain of the NKG2D ligand Mouse UL-16-binding protein-like transcript 1 (MULT1E) and mouse IL-12 (mIL-12). It is hypothesized that when expressed by tumor cells, the protein will activate NK and other killer cells using the NKG2D receptor, and deliver mIL-12 to the NK cells where it can interact with the IL-12R and enhance cytotoxicity. The fusion protein, when expressed by engineered tumor cells, indeed activated NK cells in vitro as assayed by increased production of interferon-γ and cytotoxicity and significantly reduced tumor growth in vivo. Although the study is preliminary, the data suggest that the MULT1E/mIL-12 bi-functional fusion protein is an effective activator of NK cells for cancer treatment. PMID:24572784

  1. Subnanometer Cobalt-Hydroxide-Anchored N-Doped Carbon Nanotube Forest for Bifunctional Oxygen Catalyst.

    PubMed

    Kim, Ji Eun; Lim, Joonwon; Lee, Gil Yong; Choi, Sun Hee; Maiti, Uday Narayan; Lee, Won Jun; Lee, Ho Jin; Kim, Sang Ouk

    2016-01-27

    Electrochemical oxygen redox reactions are the crucial elements for energy conversion and storage including fuel cells and metal air batteries. Despite tremendous research efforts, developing high-efficient, low-cost, and durable bifunctional oxygen catalysts remains a major challenge. We report a new class of hybrid material consisting of subnanometer thick amorphous cobalt hydroxide anchored on NCNT as a durable ORR/OER bifunctional catalyst. Although amorphous cobalt species-based catalysts are known as good OER catalysts, hybridizing with NCNT successfully enhanced ORR activity by promoting a 4e reduction pathway. Abundant charge carriers in amorphous cobalt hydroxide are found to trigger the superior OER activity with high current density and low Tafel slope as low as 36 mV/decade. A remarkably high OER turnover frequency (TOF) of 2.3 s(-1) at an overpotential of 300 mV was obtained, one of the highest values reported so far. Moreover, the catalytic activity was maintained over 120 h of cycling. The unique subnanometer scale morphology of amorphous hydroxide cobalt species along with intimate cobalt species-NCNT interaction minimizes the deactivation of catalyst during prolonged repeated cycles. PMID:26766495

  2. Determining the Origin of Half-bandgap-voltage Electroluminescence in Bifunctional Rubrene/C60 Devices.

    PubMed

    Chen, Qiusong; Jia, Weiyao; Chen, Lixiang; Yuan, De; Zou, Yue; Xiong, Zuhong

    2016-01-01

    Lowering the driving voltage of organic light-emitting diodes (OLEDs) is an important approach to reduce their energy consumption. We have fabricated a series of bifunctional devices (OLEDs and photovoltaics) using rubrene and fullerene (C60) as the active layer, in which the electroluminescence threshold voltage(~1.1 V) was half the value of the bandgap of rubrene. Magneto-electroluminescence (MEL) response of planner heterojunction diodes exhibited a small increase in response to a low magnetic field strength (<20 mT); however, a very large decay was observed at a high magnetic field strength (>20 mT). When a hole-transport layer with a low mobility was included in these devices, the MEL response reversed in shape, and simultaneously, the EL threshold voltage became larger than the bandgap voltage. When bulk heterojunction device was examined, the amplitude of MEL curves presented an anomalous voltage-dependence. Following an analysis of the MEL responses of these devices, we proposed that the EL of half-bandgap-voltage device originated from bimolecular triplet-triplet annihilation in the rubrene film, rather than from singlet excitons that formed via an interface auger recombination. This work provides critical insight into the mechanisms of OLED emission and will help advance the applications of bifunctional devices. PMID:27142285

  3. Large-scale Generation of Patterned Bubble Arrays on Printed Bi-functional Boiling Surfaces

    PubMed Central

    Choi, Chang-Ho; David, Michele; Gao, Zhongwei; Chang, Alvin; Allen, Marshall; Wang, Hailei; Chang, Chih-hung

    2016-01-01

    Bubble nucleation control, growth and departure dynamics is important in understanding boiling phenomena and enhancing nucleate boiling heat transfer performance. We report a novel bi-functional heterogeneous surface structure that is capable of tuning bubble nucleation, growth and departure dynamics. For the fabrication of the surface, hydrophobic polymer dot arrays are first printed on a substrate, followed by hydrophilic ZnO nanostructure deposition via microreactor-assisted nanomaterial deposition (MAND) processing. Wettability contrast between the hydrophobic polymer dot arrays and aqueous ZnO solution allows for the fabrication of heterogeneous surfaces with distinct wettability regions. Heterogeneous surfaces with various configurations were fabricated and their bubble dynamics were examined at elevated heat flux, revealing various nucleate boiling phenomena. In particular, aligned and patterned bubbles with a tunable departure frequency and diameter were demonstrated in a boiling experiment for the first time. Taking advantage of our fabrication method, a 6 inch wafer size heterogeneous surface was prepared. Pool boiling experiments were also performed to demonstrate a heat flux enhancement up to 3X at the same surface superheat using bi-functional surfaces, compared to a bare stainless steel surface. PMID:27034255

  4. 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

  5. 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

  6. Rolling-element bearings in China: From ancient times to the 20th century

    NASA Astrophysics Data System (ADS)

    Sun, Lie; Li, Ang

    2016-03-01

    The development of rolling-element bearings in China has spanned a long period. Based on several typical and important cases, the present article reconstructs the history of rolling-element bearings in China by dividing it into four stages according to the various characteristics of the bearings. The first stage represents the origin of rolling bearings in China, which remains controversial because of several suspected races and cages that were likely the components of bearings more than a millennium ago. At the second stage, a type of simple roller bearing was used for astronomical instruments not later than the 13th century based on clear philological and physical evidence. A similar bearing was also applied to an abridged armillary in the 17th century. Another type of spherical thrust bearings with rolling elements, which is a key component of a traditional Chinese windmill, could support a rotating shaft that moves rotationally and at an angle. At the third stage, the Chinese began studying and using the so-called Europeanstyle bearing since the 17th century. Moreover, over the last 100 years, the modern rolling bearing industry was gradually established in China, particularly because of the technology transfer from the Soviet Union in the 1950s. At the fourth stage, the Chinese government initiated the relatively rapid development of bearing technology. The government launched the "bearing movement" from the 1950s to the 1960s to establish the modern bearing industry and to promote rolling bearings as replacement for traditional sliding bearings. Furthermore, a number of large professional factories and institutions in China have continually introduced advanced technology and equipment. At present, these companies and institutions play a significant role in the international bearing industry.

  7. 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

  8. 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.

  9. 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.

  10. Hybrid Hydrostatic/Transient Roller Bearing Assembly

    NASA Technical Reports Server (NTRS)

    Justak, John F.

    1992-01-01

    Proposed bearing assembly for shaft of high-speed turbopump includes both hydrostatic and rolling-element bearings. Rolling-element bearing unloaded at high speed by centrifugal expansion of outer race and transient retainer.

  11. Two pad axially grooved hydrostatic bearing

    NASA Technical Reports Server (NTRS)

    San Andres, Luis A. (Inventor)

    1995-01-01

    A hydrostatic bearing having two axial grooves on opposite sides of the bearing for breaking the rotational symmetry in the dynamic force coefficients thus reducing the whirl frequency ratio and increasing the damping and stiffness of the hydrostatic bearing.

  12. 49 CFR 229.69 - Side bearings.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ....69 Side bearings. (a) Friction side bearings with springs designed to carry weight may not have more than 25 percent of the springs in any one nest broken. (b) Friction side bearings may not be run...

  13. 49 CFR 229.69 - Side bearings.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ....69 Side bearings. (a) Friction side bearings with springs designed to carry weight may not have more than 25 percent of the springs in any one nest broken. (b) Friction side bearings may not be run...

  14. 49 CFR 229.69 - Side bearings.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ....69 Side bearings. (a) Friction side bearings with springs designed to carry weight may not have more than 25 percent of the springs in any one nest broken. (b) Friction side bearings may not be run...

  15. Fluid Film Bearing Code Development

    NASA Technical Reports Server (NTRS)

    1995-01-01

    The next generation of rocket engine turbopumps is being developed by industry through Government-directed contracts. These turbopumps will use fluid film bearings because they eliminate the life and shaft-speed limitations of rolling-element bearings, increase turbopump design flexibility, and reduce the need for turbopump overhauls and maintenance. The design of the fluid film bearings for these turbopumps, however, requires sophisticated analysis tools to model the complex physical behavior characteristic of fluid film bearings operating at high speeds with low viscosity fluids. State-of-the-art analysis and design tools are being developed at the Texas A&M University under a grant guided by the NASA Lewis Research Center. The latest version of the code, HYDROFLEXT, is a thermohydrodynamic bulk flow analysis with fluid compressibility, full inertia, and fully developed turbulence models. It can predict the static and dynamic force response of rigid and flexible pad hydrodynamic bearings and of rigid and tilting pad hydrostatic bearings. The Texas A&M code is a comprehensive analysis tool, incorporating key fluid phenomenon pertinent to bearings that operate at high speeds with low-viscosity fluids typical of those used in rocket engine turbopumps. Specifically, the energy equation was implemented into the code to enable fluid properties to vary with temperature and pressure. This is particularly important for cryogenic fluids because their properties are sensitive to temperature as well as pressure. As shown in the figure, predicted bearing mass flow rates vary significantly depending on the fluid model used. Because cryogens are semicompressible fluids and the bearing dynamic characteristics are highly sensitive to fluid compressibility, fluid compressibility effects are also modeled. The code contains fluid properties for liquid hydrogen, liquid oxygen, and liquid nitrogen as well as for water and air. Other fluids can be handled by the code provided that the

  16. Long-Term Persistence of Bi-functionality Contributes to the Robustness of Microbial Life through Exaptation

    PubMed Central

    Sterner, Reinhard; Merkl, Rainer

    2016-01-01

    Modern enzymes are highly optimized biocatalysts that process their substrates with extreme efficiency. Many enzymes catalyze more than one reaction; however, the persistence of such ambiguities, their consequences and evolutionary causes are largely unknown. As a paradigmatic case, we study the history of bi-functionality for a time span of approximately two billion years for the sugar isomerase HisA from histidine biosynthesis. To look back in time, we computationally reconstructed and experimentally characterized three HisA predecessors. We show that these ancient enzymes catalyze not only the HisA reaction but also the isomerization of a similar substrate, which is commonly processed by the isomerase TrpF in tryptophan biosynthesis. Moreover, we found that three modern-day HisA enzymes from Proteobacteria and Thermotogae also possess low TrpF activity. We conclude that this bi-functionality was conserved for at least two billion years, most likely without any evolutionary pressure. Although not actively selected for, this trait can become advantageous in the case of a gene loss. Such exaptation is exemplified by the Actinobacteria that have lost the trpF gene but possess the bi-functional HisA homolog PriA, which adopts the roles of both HisA and TrpF. Our findings demonstrate that bi-functionality can perpetuate in the absence of selection for very long time-spans. PMID:26824644

  17. Facile synthesis of 4-vinyl- and 4-fluorovinyl-1,2,3-triazoles via bifunctional “click-olefination” reagents

    PubMed Central

    Kumar, Rakesh; Pradhan, Padmanava; Zajc, Barbara

    2011-01-01

    Modular synthesis of vinyl and fluorovinyl triazoles can be achieved from bifunctional propargyl and fluoropropargyl sulfones by Cu-catalyzed azide-alkyne ligation and Julia-Kocienski olefination. Competitive click reactions of the protio and fluoropropargyl sulfones show higher reactivity of the latter, and a preliminary DFT analysis was performed. PMID:21336351

  18. Scalable Fabrication of Nanoporous Carbon Fiber Films as Bifunctional Catalytic Electrodes for Flexible Zn-Air Batteries.

    PubMed

    Liu, Qin; Wang, Yaobing; Dai, Liming; Yao, Jiannian

    2016-04-01

    A flexible nanoporous carbon-fiber film for wearable electronics is prepared by a facile and scalable method through pyrolysis of electrospun polyimide. It exhibits excellent bifunctional electrocatalytic activities for oxygen reduction and oxygen evolution. Flexible rechargeable zinc-air batteries based on the carbon-fiber film show high round-trip efficiency and mechanical stability. PMID:26914270

  19. Bifunctional-Phosphine-Catalyzed Sequential Annulations of Allenoates and Ketimines: Construction of Functionalized Poly-heterocycle Rings.

    PubMed

    Li, Erqing; Jin, Hongxing; Jia, Penghao; Dong, Xuelin; Huang, You

    2016-09-12

    A highly stereoselective sequential annulation reaction between γ-substituted allenoates and ketimines was reported. By using bifunctional N-acyl aminophosphine catalysts, poly-heterocycle rings were obtained with high stereocontrol in good to excellent yields. The desired products have four contiguous stereogenic centers (one quaternary and three tertiary carbon centers), and only one isomer was obtained in all reactions. PMID:27529614

  20. Random bearings and their stability.

    PubMed

    Mahmoodi Baram, Reza; Herrmann, Hans J

    2005-11-25

    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. PMID:16384225

  1. Bears, Big and Little. Young Discovery Library Series.

    ERIC Educational Resources Information Center

    Pfeffer, Pierre

    This book is written for children 5 through 10. Part of a series designed to develop their curiosity, fascinate them and educate them, this volume describes: (1) the eight species of bears, including black bear, brown bear, grizzly bear, spectacled bear, sun bear, sloth bear, polar bear, and giant panda; (2) geographical habitats of bears; (3)…

  2. 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.

  3. CCPI bears first fruit

    SciTech Connect

    Wicker, K.

    2006-01-15

    In 2002, the Bush administration launched the Clean Coal Power Initiative (CCCPI) in the hope that it would develop the missing technology piece of the cleaner energy puzzle. Four years and two rounds later, the US electric power industry is seeing the first usable clean coal technologies emerge before its eyes. This article describe progress on one of the eight selected projects in the initial phase of the CCPI - led by NeuCo Inc. and carried out at Dynegy's Baldwin Energy Complex in Illinois - to increase efficiency and reduce emissions of the station's three coal-fired units with plant optimization software. In year one, a combustion/post-combustion (SCR) optimization system called CombustOpt was installed on cyclone boilers of units 1 and 2. They were also retrofitted with NeuCo's PerformanceOpt system. The fuel technology piece is MainenanceOpt to determine root causes of problems affecting unit efficiency and capacity. 5 figs.

  4. Bifunctional μ/δ Opioid Peptides: Variation of the Type and Length of the Linker Connecting the Two Components

    PubMed Central

    Ding, Jinguo; Lemieux, Carole; Chung, Nga N.; Schiller, Peter W.

    2011-01-01

    On the basis of evidence that opioid compounds with a mixed μ agonist/δ antagonist profile may produce an antinociceptive effect with low propensity to induce side effects, bifunctional opioid peptides containing the μ agonist [Dmt1]DALDA (H-Dmt-D-Arg-Phe-Lys-NH2; Dmt = 2',6’-dimethyltyrosine) connected tail-to-tail via various α,ω-diaminoalkyl- or diaminocyclohexane linkers to the δ antagonists TICP[Ψ] (H-Tyr-TicΨ[CH2-NH]Cha-Phe-OH; Cha = cyclohexylalanine, Tic = 1,2,3,4-tetrahydroisoquinoline-3-carboxylic acid), H-Dmt-Tic-OH or H-Bcp-Tic-OH (Bcp = 4'-[N-((4'-phenyl)phenethyl)carboxamido]phenylalanine) were synthesized and pharmacologically characterized in vitro. Bifunctional [Dmt1]DALDA→NH-(CH2)n-NH←TICP[Ψ] compounds (n = 0–12) showed decreasing μ and δ receptor binding affinities with increasing linker length. As expected, several of the bifunctional peptides were μ agonist/δ antagonists with low nanomolar μ and δ receptor binding affinities. However, compounds with unexpected opioid activity profiles, including a μ partial agonist/δ partial agonist, μ antagonist/δ antagonists and μ agonist/δ agonists, were also identified. These results indicate that the binding affinities and intrinsic efficacies of these bifunctional compounds at both receptors depend on the length and type of the linker connecting the μ and δ components. An important recommendation emerging from this study is that the in vitro activity profiles of bifunctional compounds containing an agonist and an antagonist component connected via a linker need to be determined prior to their pharmacological evaluation in vivo. PMID:22070627

  5. Sputter etching of hemispherical bearings

    NASA Technical Reports Server (NTRS)

    Schiesser, R. J.

    1972-01-01

    Technique was developed for fabricating three dimensional pumping grooves on gas bearings by sputter etching. Method eliminates problems such as groove nonuniformity, profile, and finish, which are associated with normal grooving methods.

  6. Mixed-mu superconducting bearings

    DOEpatents

    Hull, J.R.; Mulcahy, T.M.

    1998-03-03

    A mixed-mu superconducting bearing is disclosed including a ferrite structure disposed for rotation adjacent a stationary superconductor material structure and a stationary permanent magnet structure. The ferrite structure is levitated by said stationary permanent magnet structure. 9 figs.

  7. Mixed-mu superconducting bearings

    DOEpatents

    Hull, John R.; Mulcahy, Thomas M.

    1998-01-01

    A mixed-mu superconducting bearing including a ferrite structure disposed for rotation adjacent a stationary superconductor material structure and a stationary permanent magnet structure. The ferrite structure is levitated by said stationary permanent magnet structure.

  8. 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.

  9. 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).

  10. 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.

  11. Myrmecophagy by Yellowstone grizzly bears

    USGS Publications Warehouse

    Mattson, D.J.

    2001-01-01

    I used data collected during a study of radio-marked grizzly bears (Ursus arctos horribilis) in the Yellowstone region from 1977 to 1992 to investigate myrmecophagy by this population. Although generally not an important source of energy for the bears (averaging 8 mm long) nested in logs over small ants (6 mm long) nested under stones. Optimal conditions for consumption of ants occurred on the warmest sites with ample substrate suitable for ant nests. For ants in mounds, this occurred at low elevations at non-forested sites. For ants in logs, this occurred at low elevations or on southerly aspects where there was abundant, large-diameter, well-decomposed woody debris under an open forest canopy. Grizzly bears selected moderately decomposed logs 4a??5 dm in diameter at midpoint. Ants will likely become a more important food for Yellowstone's grizzly bears as currently important foods decline, owing to disease and warming of the regional climate.

  12. Lateral dampers for thrust bearings

    NASA Technical Reports Server (NTRS)

    Hibner, D. H.; Szafir, D. R.

    1985-01-01

    The development of lateral damping schemes for thrust bearings was examined, ranking their applicability to various engine classes, selecting the best concept for each engine class and performing an in-depth evaluation. Five major engine classes were considered: large transport, military, small general aviation, turboshaft, and non-manrated. Damper concepts developed for evaluation were: curved beam, constrained and unconstrained elastomer, hybrid boost bearing, hydraulic thrust piston, conical squeeze film, and rolling element thrust face.

  13. Polyurethane retainers for ball bearings

    NASA Technical Reports Server (NTRS)

    Christy, R. I.

    1973-01-01

    Evaluation of a new ball bearing retainer material is reported. A special composite polyurethane foam ball retainer has been developed that has virtually zero wear, is chemically inert to hydrocarbon lubricants, and stores up to 60 times as much lubricant per unit volume as the most commonly used retainer material, cotton phenolic. This new retainer concept shows promise of years of ball bearing operation without reoiling, based on life testing in high vacuum.

  14. SSME Long-life Bearings

    NASA Technical Reports Server (NTRS)

    Butner, M. F.; Murphy, B. T.

    1986-01-01

    Hybrid hydrostatic/ball bearings for LH2 and LO2 service in turbopumps were studied as a means of improving speed and life capabilities. Four hybrid bearing configurations were designed with emphasis on achieving maximum stiffness and damping. Parallel load bearings were tested at steady-state and transient conditions with LH2 (externally fed) and LN2 (internally fed). The hydrostatic elements were tested with Freon 113 for empirical determination of dynamic characteristics. Tests using an eccentric journal for loading showed the externally and internally fed hydrostatic bearings to have significant separated coefficients of direct stiffness and damping. For the internally fed bearing, the strongly speed-dependent cross-coupling stiffness arising from fluid swirl, along with significant cross-coupling damping, resulted in low net effective stiffness and damping. The test method used can produce separated coefficients with a sufficiently elliptic journal orbit; otherwise, only net effective coefficients combining direct and cross-coupling terms can be determined. Testing with nonsynchronous excitation is recommended to avoid this restriction. Investigation of hard materials, including ceramics, is recommended as a means of eliminating the need for the rolling bearing for startup and shutdown support. The testing was performed in 1984 (LH2), 1985 (LN2) and 1985-86 (Freon).

  15. 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.

  16. Gimbal bearing design considerations and friction control

    NASA Technical Reports Server (NTRS)

    Kramer, N. R.

    1979-01-01

    The design considerations of bearing selection, bearing fits, bearing installation, and thermal control are discussed for a gimbal with a high stiffness, low friction torque requirement. Tradeoffs between a quad set of small diameter spread apart or a large diameter bearing pair resulted in a cleaner, lighter, stiffer unit with the latter selection. Bearing fits were designed to eliminate clearances with tolerances of .00127 mm 00005 in) on the bearing shafts and housings. The problems in metrology are discussed and a perferred technique for measurement of small cross-section bearings described. A technique for installation to assure proper seating of the bearing is offered. Where transient thermal conditions are involved, a method of controlling bearing friction by active control of bearing temperature gradients including the use of bearing unload test curves is described.

  17. Research of singular value decomposition based on slip matrix for rolling bearing fault diagnosis

    NASA Astrophysics Data System (ADS)

    Cong, Feiyun; Zhong, Wei; Tong, Shuiguang; Tang, Ning; Chen, Jin

    2015-05-01

    Rolling element bearings are at the heart of most rotating machines and they bear the function of connectivity between the rotor and stator. It is important to distinguish the incipient fault before the bearing step into serious failure. The Slip Matrix (SM) construction method based on Singular Value Decomposition (SVD) is proposed in this paper. The SM based fault feature extraction and impulses intelligent detection methods are introduced as the key steps for rolling bearing fault diagnosis. The numerical simulation of rolling bearing fault signal is adopted which shows that the proposed method is good at fault impulses detection in strong background noise environment. The rolling element bearing accelerated life test is performed for the acquisition of experimental data of rolling bearing fault. With the rolling bearing running from normal state to failure, the initial fault signal part can be picked out from the whole life vibration data of the rolling bearing. The vibration signal is close to the nature fault signal which is acquired from a rolling bearing applied in industrial field. The analysis result shows that the proposed method has an excellent performance in rolling bearing fault detection.

  18. Oxygen electrode bifunctional electrocatalyst NiCo2O4 spinel

    NASA Technical Reports Server (NTRS)

    Fielder, William L.; Singer, Joseph

    1988-01-01

    A significant increase in energy density may be possible if a two-unit alkaline regenerative H2-O2 fuel cell is replaced with a single-unit system that uses passive means for H2O transfer and thermal control. For this single-unit system, new electrocatalysts for the O2 electrode will be required which are not only bifunctionally active but also chemically and electrochemically stable between the voltage range of about 0.7 and 1.5 V. NiCo2O4 spinel is reported to have certain characteristics that make it useful for a study of electrode fabrication techniques. High surface area NiCo2O4 powder was fabricated into unsupported, bifunctional, PTFE-bonded, porous gas fuel cell electrodes by commercial sources using varying PTFE contents and sintering temperatures. The object of this study is to measure the bifunctional activities of these electrodes and to observe what performance differences might result from different commercial electrode fabricators. O2 evolution and O2 reduction data were obtained at 80 C (31 percent KOH). An irreversible reaction (i.e., aging) occurred during O2 evolution at potentials greater than about 1.5 V. Anodic Tafel slopes of 0.06 and 0.12 V/decade were obtained for the aged electrodes. Within the range of 15 to 25 percent, the PTFE content was not a critical parameter for optimizing the electrode for O2 evolution activity. Sintering temperatures between 300 and 340 C may be adequate but heating at 275 C may not be sufficient to properly sinter the PTFE-NiCo2O4 mixture. Electrode disintegration was observed during O2 reduction. Transport of O2 to the NiCo2O4 surface became prohibitive at greater than about -0.02 A/sq cm. Cathodic Tafel slopes of -0.6 and -0.12 V/decade were assumed for the O2 reduction process. A PTFE content of 25 percent (or greater) appears to be preferable for sintering the PTFE-NiCo2O4 mixture.

  19. 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.

  20. 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.

  1. 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.

  2. BEARS: Radioactive ion beams at LBNL

    SciTech Connect

    Powell, J.; Guo, F.Q.; Haustein, P.E.

    1998-07-01

    BEARS (Berkeley Experiments with Accelerated Radioactive Species) is an initiative to develop a radioactive ion-beam capability at Lawrence Berkeley National Laboratory. The aim is to produce isotopes at an existing medical cyclotron and to accelerate them at the 88 inch Cyclotron. To overcome the 300-meter physical separation of these two accelerators, a carrier-gas transport system will be used. At the terminus of the capillary, the carrier gas will be separated and the isotopes will be injected into the 88 inch Cyclotron`s Electron Cyclotron Resonance (ECR) ion source. The first radioactive beams to be developed will include 20-min {sup 11}C and 70-sec {sup 14}O, produced by (p,n) and (p,{alpha}) reactions on low-Z targets. A test program is currently being conducted at the 88 inch Cyclotron to develop the parts of the BEARS system. Preliminary results of these tests lead to projections of initial {sup 11}C beams of up to 2.5 {times} 10{sup 7} ions/sec and {sup 14}O beams of 3 {times} 10{sup 5} ions/sec.

  3. Prototype ventricular assist device supported on magnetic bearings

    SciTech Connect

    Allaire, P.E.; Maslen, E.H.; Kim, H.C.; Olsen, D.B.; Bearnson, G.D.

    1995-12-31

    Mechanical artificial hearts are now expected to be used as assist or total replacements for failing human hearts, if a reliable, anatomically appropriate design is developed. Initially, ventricular assist or total replacement devices were pulsatile air driven units containing a flexing polymeric diaphragm and two valves for each ventricle. Many reliability problems were encountered. Recently, attention has been focused on axial or centrifugal continuous flow blood pumps. Magnetic bearings employed in such devices offer the advantages of no required lubrication and large operating clearances. This paper describes a prototype continuous flow pump supported in magnetic bearings. The pump performance was measured in a simulated adult human circulation system. It delivered 6 liters/min of flow at 100 mm Hg differential head operating at 2,400 rpm in water. The pump is totally magnetically supported in four magnetic bearings - two radial and two thrust. The geometry and other properties of the bearings are described. Bearing parameters such as load capacity, current gains, and open loop stiffness are discussed. Bearing coil currents were measured during operation in air and water. The rotor was operated in various orientations to determine the actuator current gains. These values were then used to estimate the radial and thrust forces acting on the rotor in both air and water.

  4. 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

    ... Energy Regulatory Commission 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 Soliciting Comments and Motions To Intervene On October 25, 2012, Black Bear Hydro Partners, LLC, sole licensee (transferor)...

  5. 49 CFR 40.385 - Who bears the burden of proof in a PIE proceeding?

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 49 Transportation 1 2014-10-01 2014-10-01 false Who bears the burden of proof in a PIE proceeding... TRANSPORTATION WORKPLACE DRUG AND ALCOHOL TESTING PROGRAMS Public Interest Exclusions § 40.385 Who bears the burden of proof in a PIE proceeding? (a) As the proponent of issuing a PIE, the initiating official...

  6. 49 CFR 40.385 - Who bears the burden of proof in a PIE proceeding?

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 49 Transportation 1 2011-10-01 2011-10-01 false Who bears the burden of proof in a PIE proceeding... TRANSPORTATION WORKPLACE DRUG AND ALCOHOL TESTING PROGRAMS Public Interest Exclusions § 40.385 Who bears the burden of proof in a PIE proceeding? (a) As the proponent of issuing a PIE, the initiating official...

  7. 49 CFR 40.385 - Who bears the burden of proof in a PIE proceeding?

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 49 Transportation 1 2012-10-01 2012-10-01 false Who bears the burden of proof in a PIE proceeding... TRANSPORTATION WORKPLACE DRUG AND ALCOHOL TESTING PROGRAMS Public Interest Exclusions § 40.385 Who bears the burden of proof in a PIE proceeding? (a) As the proponent of issuing a PIE, the initiating official...

  8. 49 CFR 40.385 - Who bears the burden of proof in a PIE proceeding?

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 49 Transportation 1 2013-10-01 2013-10-01 false Who bears the burden of proof in a PIE proceeding... TRANSPORTATION WORKPLACE DRUG AND ALCOHOL TESTING PROGRAMS Public Interest Exclusions § 40.385 Who bears the burden of proof in a PIE proceeding? (a) As the proponent of issuing a PIE, the initiating official...

  9. 77 FR 53844 - Ball Bearings and Parts Thereof From France and Italy: Rescission of Antidumping Duty...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-09-04

    ... Duty Administrative Reviews and Request for Revocations in Part, 77 FR 40565 (July 10, 2012... International Trade Administration Ball Bearings and Parts Thereof From France and Italy: Rescission of... (the Department) initiated administrative reviews of the antidumping duty orders on ball bearings...

  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 (γ-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. Mono- and bi-functional arenethiols as surfactants for gold nanoparticles: synthesis and characterization

    NASA Astrophysics Data System (ADS)

    Vitale, Floriana; Fratoddi, Ilaria; Battocchio, Chiara; Piscopiello, Emanuela; Tapfer, Leander; Russo, Maria Vittoria; Polzonetti, Giovanni; Giannini, Cinzia

    2011-12-01

    Stable gold nanoparticles stabilized by different mono and bi-functional arenethiols, namely, benzylthiol and 1,4-benzenedimethanethiol, have been prepared by using a modified Brust's two-phase synthesis. The size, shape, and crystalline structure of the gold nanoparticles have been determined by high-resolution electron microscopy and full-pattern X-ray powder diffraction analyses. Nanocrystals diameters have been tuned in the range 2 ÷ 9 nm by a proper variation of Au/S molar ratio. The chemical composition of gold nanoparticles and their interaction with thiols have been investigated by X-ray photoelectron spectroscopy. In particular, the formation of networks has been observed with interconnected gold nanoparticles containing 1,4-benzenedimethanethiol as ligand.

  12. Bi-functional Mo-doped WO3 nanowire array electrochromism-plus electrochemical energy storage.

    PubMed

    Zhou, D; Shi, F; Xie, D; Wang, D H; Xia, X H; Wang, X L; Gu, C D; Tu, J P

    2016-03-01

    Metal-doping is considered to be an effective way for construction of advanced semiconducting metal oxides with tailored physicochemical properties. Herein, Mo-doped WO3 nanowire arrays are rationally fabricated by a sulfate-assisted hydrothermal method. Compared to the pure WO3, the optimized Mo-doped WO3 nanowire arrays exhibit improved electrochromic properties with fast switching speed (3.2s and 2.6s for coloration and bleaching, respectively), significant optical modulation (56.7% at 750nm, 83.0% at 1600nm and 48.5% at 10μm), high coloration efficiency (123.5cm(2)C(-1)) and excellent cycling stability. In addition, as a proof of concept, the Mo-doped WO3 nanowire arrays are demonstrated with electrochemical energy storage monitored by the electrochromism. This electrode design protocol can provide an alternative way for developing high-performance active materials for bi-functional electrochromic batteries. PMID:26669497

  13. Novel 3-nitrotriazole-based amides and carbinols as bifunctional anti-Chagasic agents

    PubMed Central

    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

    2015-01-01

    3-Nitro-1H-1,2,4-triazole-based amides with a linear, rigid core and 3-nitrotriazole-based fluconazole analogs 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 14α-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

  14. Chimeric bifunctional oligonucleotides as a novel tool to invade telomerase assembly

    PubMed Central

    Azhibek, Dulat; Zvereva, Maria; Zatsepin, Timofei; Rubtsova, Maria; Dontsova, Olga

    2014-01-01

    Telomerase is a key participant in the telomere length maintaining system in eukaryotic cells. Telomerase RNA and protein reverse transcriptase subunits are essential for the appearance of active telomerase in vitro. Telomerase is active in many cancer types and is a potential target for anticancer drug development. Here we report a new approach for impairing telomerase function at the stage of human telomerase assembly. The approach is based on the application of chimeric bifunctional oligonucleotides that contain two oligonucleotide parts complementary to the functional domains of telomerase RNA connected with non-nucleotide linkers in different orientations (5′-3′, 5′-5′ or 3′-3′). Such chimeras inhibited telomerase in vitro in the nM range, but were effective in vivo in sub-nM concentrations, predominantly due to their effect on telomerase assembly and dimerization. PMID:25081209

  15. Cage-like bifunctional chelators, copper-64 radiopharmaceuticals and PET imaging using the same

    DOEpatents

    Conti, Peter S.; Cai, Hancheng; Li, Zibo; Liu, Shuanglong

    2016-08-02

    Disclosed is a class of versatile Sarcophagine based bifunctional chelators (BFCs) containing a hexa-aza cage for labeling with metals having either imaging, therapeutic or contrast applications radiolabeling and one or more linkers (A) and (B). The compounds have the general formula ##STR00001## where A is a functional group selected from group consisting of an amine, a carboxylic acid, an ester, a carbonyl, a thiol, an azide and an alkene, and B is a functional group selected from the group consisting of hydrogen, an amine, a carboxylic acid, and ester, a carbonyl, a thiol, an azide and an alkene. Also disclosed are conjugate of the BFC and a targeting moiety, which may be a peptide or antibody. Also disclosed are metal complexes of the BFC/targeting moiety conjugates that are useful as radiopharmaceuticals, imaging agents or contrast agents.

  16. Polarization holograms in a bifunctional amorphous polymer exhibiting equal values of photoinduced linear and circular birefringences.

    PubMed

    Provenzano, Clementina; Pagliusi, Pasquale; Cipparrone, Gabriella; Royes, Jorge; Piñol, Milagros; Oriol, Luis

    2014-10-01

    Light-controlled molecular alignment is a flexible and useful strategy introducing novelty in the fields of mechanics, self-organized structuring, mass transport, optics, and photonics and addressing the development of smart optical devices. Azobenzene-containing polymers are well-known photocontrollable materials with large and reversible photoinduced optical anisotropies. The vectorial holography applied to these materials enables peculiar optical devices whose properties strongly depend on the relative values of the photoinduced birefringences. Here is reported a polarization holographic recording based on the interference of two waves with orthogonal linear polarization on a bifunctional amorphous polymer that, exceptionally, exhibits equal values of linear and circular birefringence. The peculiar photoresponse of the material coupled with the holographic technique demonstrates an optical device capable of decomposing the light into a set of orthogonally polarized linear components. The holographic structures are theoretically described by the Jones matrices method and experimentally investigated. PMID:25187982

  17. Oxychlorination-Dehydrochlorination Chemistry on Bifunctional Ceria Catalysts for Intensified Vinyl Chloride Production.

    PubMed

    Scharfe, Matthias; Lira-Parada, Pedro A; Paunović, Vladimir; Moser, Maximilian; Amrute, Amol P; Pérez-Ramírez, Javier

    2016-02-24

    Ceria catalyzes the one-step production of the vinyl chloride monomer (VCM) from ethylene with a high yield because of its bifunctional character: redox centers oxychlorinate ethylene to ethylene dichloride (EDC), which is subsequently dehydrochlorinated to VCM over strong acid sites generated in situ. Nanocrystalline CeO2 and CeO2-ZrO2 lead to a VCM yield of 25 % in a single pass, outperforming the best reported systems and reaching industrially attractive levels. The use of CeO2 intensifies the current two-step process within PVC production encompassing CuCl2 -catalyzed oxychlorination and thermal cracking. In addition, ceria-based materials offer stability advantages with respect to the archetypical CuCl2 -based catalysts. PMID:26823027

  18. 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.

  19. The fabrication of a bifunctional oxygen electrode without carbon components for alkaline secondary batteries

    NASA Astrophysics Data System (ADS)

    Price, Stephen W. T.; Thompson, Stephen J.; Li, Xiaohong; Gorman, Scott F.; Pletcher, Derek; Russell, Andrea E.; Walsh, Frank C.; Wills, Richard G. A.

    2014-08-01

    The fabrication of a gas diffusion electrode (GDE) without carbon components is described. It is therefore suitable for use as a bifunctional oxygen electrode in alkaline secondary batteries. The electrode is fabricated in two stages (a) the formation of a PTFE-bonded nickel powder layer on a nickel foam substrate and (b) the deposition of a NiCo2O4 spinel electrocatalyst layer by dip coating in a nitrate solution and thermal decomposition. The influence of modifications to the procedure on the performance of the GDEs in 8 M NaOH at 333 K is described. The GDEs can support current densities up to 100 mA cm-2 with state-of-the-art overpotentials for both oxygen evolution and oxygen reduction. Stable performance during >50 successive, 1 h oxygen reduction/evolution cycles at a current density of 50 mA cm-2 has been achieved.

  20. A Bifunctional Electrocatalyst for Oxygen Evolution and Oxygen Reduction Reactions in Water

    PubMed Central

    Faschinger, Felix; Chattopadhyay, Samir; Bhakta, Snehadri; Mondal, Biswajit; Elemans, Johannes A. A. W.; Müllegger, Stefan; Tebi, Stefano; Koch, Reinhold; Klappenberger, Florian; Paszkiewicz, Mateusz; Barth, Johannes V.; Rauls, Eva; Aldahhak, Hazem; Schmidt, Wolf Gero

    2016-01-01

    Abstract Oxygen reduction and water oxidation are two key processes in fuel cell applications. The oxidation of water to dioxygen is a 4 H+/4 e− process, while oxygen can be fully reduced to water by a 4 e−/4 H+ process or partially reduced by fewer electrons to reactive oxygen species such as H2O2 and O2 −. We demonstrate that a novel manganese corrole complex behaves as a bifunctional catalyst for both the electrocatalytic generation of dioxygen as well as the reduction of dioxygen in aqueous media. Furthermore, our combined kinetic, spectroscopic, and electrochemical study of manganese corroles adsorbed on different electrode materials (down to a submolecular level) reveals mechanistic details of the oxygen evolution and reduction processes. PMID:27478281

  1. A Bifunctional Electrocatalyst for Oxygen Evolution and Oxygen Reduction Reactions in Water

    PubMed Central

    Faschinger, Felix; Chattopadhyay, Samir; Bhakta, Snehadri; Mondal, Biswajit; Elemans, Johannes A. A. W.; Müllegger, Stefan; Tebi, Stefano; Koch, Reinhold; Klappenberger, Florian; Paszkiewicz, Mateusz; Barth, Johannes V.; Rauls, Eva; Aldahhak, Hazem; Schmidt, Wolf Gero

    2016-01-01

    Abstract Oxygen reduction and water oxidation are two key processes in fuel cell applications. The oxidation of water to dioxygen is a 4 H+/4 e− process, while oxygen can be fully reduced to water by a 4 e−/4 H+ process or partially reduced by fewer electrons to reactive oxygen species such as H2O2 and O2 −. We demonstrate that a novel manganese corrole complex behaves as a bifunctional catalyst for both the electrocatalytic generation of dioxygen as well as the reduction of dioxygen in aqueous media. Furthermore, our combined kinetic, spectroscopic, and electrochemical study of manganese corroles adsorbed on different electrode materials (down to a submolecular level) reveals mechanistic details of the oxygen evolution and reduction processes. PMID:26773287

  2. Bifunctional hairy silica nanoparticles as high-performance additives for lubricant

    PubMed Central

    Sui, Tianyi; Song, Baoyu; Wen, Yu-ho; Zhang, Feng

    2016-01-01

    Bifunctional hairy silica nanoparticles (BHSNs), which are silica nanoparticles covered with alkyl and amino organic chains, were prepared as high-performance additives for lubricants. Compared with hairy silica nanoparticles covered by a single type of organic chain, binary hairy silica nanoparticles exhibit the advantages of both types of organic chains, which exhibit excellent compatibility with lubricants and adsorbability to metal surfaces. Nanoparticles with different ratios of amino and alkyl ligands were investigated. In comparison to an untreated lubricant, BHSNs reduce the friction coefficient and wear scar diameter by 40% and 60%, respectively. The wear mechanism of BHSNs was investigated, and the protective and filling effect of the nanoparticles improved because of collaboration of amino and alkyl ligands. PMID:26936117

  3. A crystal structure of the bifunctional antibiotic simocyclinone D8, bound to DNA gyrase.

    PubMed

    Edwards, Marcus J; Flatman, Ruth H; Mitchenall, Lesley A; Stevenson, Clare E M; Le, Tung B K; Clarke, Thomas A; McKay, Adam R; Fiedler, Hans-Peter; Buttner, Mark J; Lawson, David M; Maxwell, Anthony

    2009-12-01

    Simocyclinones are bifunctional antibiotics that inhibit bacterial DNA gyrase by preventing DNA binding to the enzyme. We report the crystal structure of the complex formed between the N-terminal domain of the Escherichia coli gyrase A subunit and simocyclinone D8, revealing two binding pockets that separately accommodate the aminocoumarin and polyketide moieties of the antibiotic. These are close to, but distinct from, the quinolone-binding site, consistent with our observations that several mutations in this region confer resistance to both agents. Biochemical studies show that the individual moieties of simocyclinone D8 are comparatively weak inhibitors of gyrase relative to the parent compound, but their combination generates a more potent inhibitor. Our results should facilitate the design of drug molecules that target these unexploited binding pockets. PMID:19965760

  4. A Bifunctional Electrocatalyst for Oxygen Evolution and Oxygen Reduction Reactions in Water.

    PubMed

    Schöfberger, Wolfgang; Faschinger, Felix; Chattopadhyay, Samir; Bhakta, Snehadri; Mondal, Biswajit; Elemans, Johannes A A W; Müllegger, Stefan; Tebi, Stefano; Koch, Reinhold; Klappenberger, Florian; Paszkiewicz, Mateusz; Barth, Johannes V; Rauls, Eva; Aldahhak, Hazem; Schmidt, Wolf Gero; Dey, Abhishek

    2016-02-12

    Oxygen reduction and water oxidation are two key processes in fuel cell applications. The oxidation of water to dioxygen is a 4 H(+)/4 e(-) process, while oxygen can be fully reduced to water by a 4 e(-)/4 H(+) process or partially reduced by fewer electrons to reactive oxygen species such as H2O2 and O2(-). We demonstrate that a novel manganese corrole complex behaves as a bifunctional catalyst for both the electrocatalytic generation of dioxygen as well as the reduction of dioxygen in aqueous media. Furthermore, our combined kinetic, spectroscopic, and electrochemical study of manganese corroles adsorbed on different electrode materials (down to a submolecular level) reveals mechanistic details of the oxygen evolution and reduction processes. PMID:26773287

  5. Bifunctional hairy silica nanoparticles as high-performance additives for lubricant.

    PubMed

    Sui, Tianyi; Song, Baoyu; Wen, Yu-Ho; Zhang, Feng

    2016-01-01

    Bifunctional hairy silica nanoparticles (BHSNs), which are silica nanoparticles covered with alkyl and amino organic chains, were prepared as high-performance additives for lubricants. Compared with hairy silica nanoparticles covered by a single type of organic chain, binary hairy silica nanoparticles exhibit the advantages of both types of organic chains, which exhibit excellent compatibility with lubricants and adsorbability to metal surfaces. Nanoparticles with different ratios of amino and alkyl ligands were investigated. In comparison to an untreated lubricant, BHSNs reduce the friction coefficient and wear scar diameter by 40% and 60%, respectively. The wear mechanism of BHSNs was investigated, and the protective and filling effect of the nanoparticles improved because of collaboration of amino and alkyl ligands. PMID:26936117

  6. Development and computational modeling of novel bifunctional organophosphorus extractants for lanthanoid separation

    SciTech Connect

    Goto, Masahiro; Matsumoto, Satoshi; Uezu, Kazuya; Nakashio, Fumiyuki; Yoshizuka, Kazuharu; Inoue, Katsutoshi

    1999-08-01

    Novel organophosphorus extractants, which have two functional groups in the molecular structure, have been developed for the separation of lanthanoids using the liquid-liquid extraction technique. The separation efficiency and extractability of the novel extractants were investigated for nine lanthanoids. These bifunctional extractants have an extremely high extractability to all the lanthanoids compared to those of commercially available organophosphorus extractants. Two isomers having an identical chemical formulation show significantly different behaviors in lanthanoid extraction. This means that the extraction and separation abilities are quite sensitive to the structure of the spacer connecting the two functional groups. The authors also discuss the experimental results with a computational modeling by means of molecular mechanics and semiempirical molecular orbital methods. The novel molecular mechanics (MM) calculation program MOMEC enables them to analyze the stable conformation of a series of lanthanoid complexes. The calculation suggests that the structural effect of the spacer is one of the decisive factors for enhancing selectivity and extractability in lanthanoid extraction.

  7. Bifunctional Nanoparticle-SILP Catalysts (NPs@SILP) for the Selective Deoxygenation of Biomass Substrates

    SciTech Connect

    Luska, Kylie L.; Julis, Jennifer; Stavitski, Eli; Zakharov, Dmitri N.; Adams, Alina; Leitner, Walter

    2014-08-27

    We immobilized ruthenium nanoparticles onto an acidic supported ionic liquid phase (RuNPs@SILP) in the development of bifunctional catalysts for the selective deoxygenation of biomass substrates. RuNPs@SILPs possessed high catalytic activities, selectivities and recyclabilities in the hydrogenolytic deoxygenation and ring opening of C8- and C9-substrates derived from furfural or 5-hydroxymethylfurfural and acetone. When we tailor the acidity of the SILP through the ionic liquid loading provided a molecular parameter by which the catalytic activity and selectivity of the RuNPs@SILPs were controlled to provide a flexible catalyst system toward the formation of different classes of value-added products: cyclic ethers, primary alcohols or aliphatic ethers.

  8. 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

  9. Synthesis and evaluation of novel bifunctional oligomer-based composites for dental applications.

    PubMed

    Xie, Dong; Chung, Il-Doo; Wang, Guigui; Mays, Jimmy

    2006-01-01

    Five novel bifunctional oligomers containing both carboxylic acid and methacrylate groups are synthesized, characterized, and used to formulate compomers by mixing with strontium fluoroaluminosilicate glass powder at a filler level of 75% (by weight). Compressive strength (CS) of the cements and viscosity of the resin liquids are used as screening tools to find the optimal formulation. Diametral tensile (DTS) and flexural strengths (FS) are also determined. Results show that the oligomers derivatized with glycerol dimethacrylate exhibit higher CS than those with 2-hydroxyethyl methacrylate. The CS increases with increasing diluent content, filler level, and light-exposure time. During aging, the cement shows an increase of strength over 24 h and then remains unaltered for up to 3 months. The experimental compomer is 45 and 69% higher in CS, 35 and 174% higher in DTS, and 39 and 170% higher in FS, respectively, as compared to Dyract and Fuji II LC. PMID:16364963

  10. A novel copper(II) coordination polymer with carboxylate and isoindol backbones of a bifunctional ligand

    NASA Astrophysics Data System (ADS)

    Patra, Ayan; Sen, Tamal K.; Musie, Ghezai T.; Mandal, Swadhin K.; Bera, Manindranath

    2013-09-01

    The reaction of a bifunctional ligand, 3-(1-oxo-1,3-dihydro-isoindol-2-yl)-propionic acid (Hpda) with Cu(NO3)2ṡ3H2O in methanol-water in the presence of NaOH at room temperature produces a novel dinuclear copper(II) coordination polymer [Cu2(pda)4]n. The complex is fully characterized in the solid state as well as in solution using various analytical techniques including single crystal X-ray diffraction study. The single crystal X-ray structure analysis reveals that the monomeric unit of complex consists of Cu2(O2CR)4 paddlewheel building unit, where the two copper centers acquire a distorted square pyramidal geometry with amide oxygen of the isoindol ring of an adjacent Hpda ligand sitting on the axial positions.

  11. "Click" chemistry mildly stabilizes bifunctional gold nanoparticles for sensing and catalysis.

    PubMed

    Li, Na; Zhao, Pengxiang; Liu, Na; Echeverria, María; Moya, Sergio; Salmon, Lionel; Ruiz, Jaime; Astruc, Didier

    2014-07-01

    A large family of bifunctional 1,2,3-triazole derivatives that contain both a polyethylene glycol (PEG) chain and another functional fragment (e.g., a polymer, dendron, alcohol, carboxylic acid, allyl, fluorescence dye, redox-robust metal complex, or a β-cyclodextrin unit) has been synthesized by facile "click" chemistry and mildly coordinated to nanogold particles, thus providing stable water-soluble gold nanoparticles (AuNPs) in the size range 3.0-11.2 nm with various properties and applications. In particular, the sensing properties of these AuNPs are illustrated through the detection of an analogue of a warfare agent (i.e., sulfur mustard) by means of a fluorescence "turn-on" assay, and the catalytic activity of the smallest triazole-AuNPs (core of 3.0 nm) is excellent for the reduction of 4-nitrophenol in water. PMID:24891131

  12. Dyes as bifunctional markers of DNA hybridization on surfaces and mutation detection.

    PubMed

    García-Mendiola, Tania; Cerro, María Ramos; López-Moreno, José María; Pariente, Félix; Lorenzo, Encarnación

    2016-10-01

    The interaction of small molecules with DNA has found diagnostic and therapeutic applications. In this work, we propose the use of two different dyes, in particular Azure A and Safranine, as bifunctional markers of on-surface DNA hybridization and potent tools for screening of specific gene mutations directly in real DNA PCR amplicons extracted from blood cells. By combining spectroscopic and electrochemical methods we demonstrate that both dyes can interact with single and double stranded DNA to a different extent, allowing reliable hybridization detection. From these data, we have also elucidated the nature of the interaction. We conclude that the binding mode is fundamentally intercalative with an electrostatic component. The dye fluorescence allows their use as nucleic acid stains for the detection of on-surfaces DNA hybridization. Its redox activity is exploited in the development of selective electrochemical DNA biosensors. PMID:27317997

  13. Bifunctional hairy silica nanoparticles as high-performance additives for lubricant

    NASA Astrophysics Data System (ADS)

    Sui, Tianyi; Song, Baoyu; Wen, Yu-Ho; Zhang, Feng

    2016-03-01

    Bifunctional hairy silica nanoparticles (BHSNs), which are silica nanoparticles covered with alkyl and amino organic chains, were prepared as high-performance additives for lubricants. Compared with hairy silica nanoparticles covered by a single type of organic chain, binary hairy silica nanoparticles exhibit the advantages of both types of organic chains, which exhibit excellent compatibility with lubricants and adsorbability to metal surfaces. Nanoparticles with different ratios of amino and alkyl ligands were investigated. In comparison to an untreated lubricant, BHSNs reduce the friction coefficient and wear scar diameter by 40% and 60%, respectively. The wear mechanism of BHSNs was investigated, and the protective and filling effect of the nanoparticles improved because of collaboration of amino and alkyl ligands.

  14. 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 14α-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

  15. Mono- and bi-functional arenethiols as surfactants for gold nanoparticles: synthesis and characterization

    PubMed Central

    2011-01-01

    Stable gold nanoparticles stabilized by different mono and bi-functional arenethiols, namely, benzylthiol and 1,4-benzenedimethanethiol, have been prepared by using a modified Brust's two-phase synthesis. The size, shape, and crystalline structure of the gold nanoparticles have been determined by high-resolution electron microscopy and full-pattern X-ray powder diffraction analyses. Nanocrystals diameters have been tuned in the range 2 ÷ 9 nm by a proper variation of Au/S molar ratio. The chemical composition of gold nanoparticles and their interaction with thiols have been investigated by X-ray photoelectron spectroscopy. In particular, the formation of networks has been observed with interconnected gold nanoparticles containing 1,4-benzenedimethanethiol as ligand. PMID:21711615

  16. Mechanistic Insights into the Mode of Action of Bifunctional Pyrrolidine-Squaramide-Derived Organocatalysts.

    PubMed

    Roca-López, David; Uria, Uxue; Reyes, Efraim; Carrillo, Luisa; Jørgensen, Karl Anker; Vicario, Jose L; Merino, Pedro

    2016-01-18

    The catalytic modes of action of three squaramide-derived bifunctional organocatalysts have been investigated using DFT methods. The [5+2] cycloaddition between oxidopyrylium ylides and enals was used as the model reaction. Two primary modes were possible for the different catalysts studied. The preference for one mode over the other was due to the possibility of additional favorable π-π interactions between the hydrogen-bond activated pyrylium ylide and an electron-deficient aromatic ring bonded to the squaramide NH group. The model can be extended to other reactions catalyzed by the same catalysts, such as formal [2+2] cycloadditions between nitroalkenes and α,β-unsaturated aldehydes. The computational results were in excellent concurrence with the available experimental reports on the observed total enantioselectivity and differences in diastereoselectivity depending on the substrate and the reaction. PMID:26612630

  17. 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

  18. A Cascade-Reaction Nanoreactor Composed of a Bifunctional Molecularly Imprinted Polymer that Contains Pt Nanoparticles.

    PubMed

    Wang, Jiao; Zhu, Maiyong; Shen, Xiaojuan; Li, Songjun

    2015-05-11

    This study was aimed at addressing the present challenge of cascade reactions, namely, how to furnish the catalysts with desired and hierarchical catalytic ability. This issue was addressed by constructing a cascade-reaction nanoreactor made of a bifunctional molecularly imprinted polymer containing acidic catalytic sites and Pt nanoparticles. The acidic catalytic sites within the imprinted polymer allowed one specified reaction, whereas the encapsulated Pt nanoparticles were responsible for another coupled reaction. To that end, the unique imprinted polymer was fabricated by using two well-coupled templates, that is, 4-nitrophenyl acetate and 4-nitrophenol. The catalytic hydrolysis of the former compound at the acidic catalytic sites led to the formation of the latter compound, which was further reduced by the encapsulated Pt nanoparticles to 4-aminophenol. Therefore, this nanoreactor demonstrated a catalytic-cascade ability. This protocol opens up the opportunity to develop functional catalysts for complicated chemical processes. PMID:25846700

  19. Bifunctional mechanism of catalysis in reactions leading to formation of /alpha/-amino ketones

    SciTech Connect

    Popov, A.F.; Anikeev, A.V.

    1988-10-20

    The kinetics of the reaction of /alpha/-bromoacetophenone and benzyl bromide with aniline and pyridine in the presence of additions of acetic acid and phenol in benzene at 30/degree/C were investigated. The catalytic effects due to the activity of the uncombined forms of the catalyst, their dimers, and their 1:1 complexes with the amines were separated quantitatively. The change in the catalytic activity of the respective particles in the solutions with variation in the structure of the reagents is examined, and possible mechanisms for the catalytic reactions are discussed on this basis. It is concluded that there is a bifunctional mechanism of catalysis by acetic acid in the reaction of /alpha/-bromoacetophenone with aniline.

  20. RNA Secondary Structure Modulates FMRP's Bi-Functional Role in the MicroRNA Pathway.

    PubMed

    Kenny, Phillip; Ceman, Stephanie

    2016-01-01

    MicroRNAs act by post-transcriptionally regulating the gene expression of 30%-60% of mammalian genomes. MicroRNAs are key regulators in all cellular processes, though the mechanism by which the cell activates or represses microRNA-mediated translational regulation is poorly understood. In this review, we discuss the RNA binding protein Fragile X Mental Retardation Protein (FMRP) and its role in microRNA-mediated translational regulation. Historically, FMRP is known to function as a translational suppressor. However, emerging data suggests that FMRP has both an agonistic and antagonistic role in regulating microRNA-mediated translational suppression. This bi-functional role is dependent on FMRP's interaction with the RNA helicase Moloney leukemia virus 10 (MOV10), which modifies the structural landscape of bound mRNA, therefore facilitating or inhibiting its association with the RNA-Induced Silencing Complex. PMID:27338369

  1. Eggplant-derived microporous carbon sheets: towards mass production of efficient bifunctional oxygen electrocatalysts at low cost for rechargeable Zn-air batteries.

    PubMed

    Li, Bing; Geng, Dongsheng; Lee, Xinjing Shannon; Ge, Xiaoming; Chai, Jianwei; Wang, Zhijuan; Zhang, Jie; Liu, Zhaolin; Hor, T S Andy; Zong, Yun

    2015-05-25

    We report 2D microporous carbon sheets with high surface area, derived from eggplant via simple carbonization and KOH activation, as low cost yet efficient bifunctional catalysts for high performance rechargeable zinc-air batteries. PMID:25920952

  2. Bear reintroduction: Lessons and challenges

    USGS Publications Warehouse

    Clark, Joseph D.; Huber, Djuro; Servheen, Christopher

    2002-01-01

    Reintroduction is defined as an attempt to establish a species in an area that was once part of its historical range, but from which it has been extirpated or become extinct. Historically, one of the most successful programs was the reintroduction of 254 American black bears (Ursus americanus) from Minnesota to the Interior Highlands of Arkansas in the 1960s; that population has grown to >2,500 today. More recent efforts have involved fewer but better monitored animals and have sometimes employed techniques to improve site fidelity and survival. In Pennsylvania, for example, pregnant female American black bears were successfully translocated from winter dens, the premise being that the adult females would be less likely to return because of the presence of young cubs. That winter-release technique was compared to summer trapping and release in Tennessee; winter releases resulted in greater survival and reduced post-release movements. Homing has not been a problem for small numbers of brown bears (Ursus arctos) reintroduced to the Cabinet-Yaak ecosystem in Montana and Idaho and to the mountains of Austria and France. Reintroduction success appears to be correlated with translocation distance and is greater for subadults and females. As with any small population, reintroduced bear populations are susceptible to environmental variation and stochastic demographic and genetic processes. Although managers have focused on these biological barriers, sociopolitical impediments to bear reintroduction are more difficult to overcome. Poor public acceptance and understanding of bears are the main reasons some reintroduction programs have been derailed. Consequently, the public should be involved in the reintroduction process from the outset; overcoming negative public perceptions about bear reintroduction will be our greatest challenge.

  3. Hydrostatic liquid-bearing for precision gyro

    NASA Technical Reports Server (NTRS)

    Sgambati, R. J.

    1971-01-01

    Unit with 2W power increase and slightly larger overall dimensions performs as well as or better than its gas-bearing counterpart. Liquid-bearings are built by reworking serviceable gas-bearing components /sleeves, endplates, and cylinders/. Hydrostatic bearing is self-centered, requiring no magnetic suspension or centering jewel.

  4. 36 CFR 13.1236 - Bear orientation.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 36 Parks, Forests, and Public Property 1 2010-07-01 2010-07-01 false Bear orientation. 13.1236... Developed Area § 13.1236 Bear orientation. All persons visiting the BCDA must receive an NPS-approved Bear Orientation. Failure to receive an NPS-approved Bear Orientation is prohibited....

  5. 36 CFR 13.1236 - Bear orientation.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 36 Parks, Forests, and Public Property 1 2012-07-01 2012-07-01 false Bear orientation. 13.1236... Developed Area § 13.1236 Bear orientation. All persons visiting the BCDA must receive an NPS-approved Bear Orientation. Failure to receive an NPS-approved Bear Orientation is prohibited....

  6. 36 CFR 13.1236 - Bear orientation.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 36 Parks, Forests, and Public Property 1 2014-07-01 2014-07-01 false Bear orientation. 13.1236... Developed Area § 13.1236 Bear orientation. All persons visiting the BCDA must receive an NPS-approved Bear Orientation. Failure to receive an NPS-approved Bear Orientation is prohibited....

  7. 49 CFR 229.69 - Side bearings.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 49 Transportation 4 2012-10-01 2012-10-01 false Side bearings. 229.69 Section 229.69....69 Side bearings. (a) Friction side bearings with springs designed to carry weight may not have more than 25 percent of the springs in any one nest broken. (b) Friction side bearings may not be run...

  8. 36 CFR 13.1236 - Bear orientation.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 36 Parks, Forests, and Public Property 1 2011-07-01 2011-07-01 false Bear orientation. 13.1236... Developed Area § 13.1236 Bear orientation. All persons visiting the BCDA must receive an NPS-approved Bear Orientation. Failure to receive an NPS-approved Bear Orientation is prohibited....

  9. 49 CFR 229.69 - Side bearings.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 49 Transportation 4 2011-10-01 2011-10-01 false Side bearings. 229.69 Section 229.69....69 Side bearings. (a) Friction side bearings with springs designed to carry weight may not have more than 25 percent of the springs in any one nest broken. (b) Friction side bearings may not be run...

  10. 36 CFR 13.1236 - Bear orientation.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 36 Parks, Forests, and Public Property 1 2013-07-01 2013-07-01 false Bear orientation. 13.1236... Developed Area § 13.1236 Bear orientation. All persons visiting the BCDA must receive an NPS-approved Bear Orientation. Failure to receive an NPS-approved Bear Orientation is prohibited....

  11. Proteasome inhibitors act as bifunctional antagonists of human immunodeficiency virus type 1 latency and replication

    PubMed Central

    2013-01-01

    Background Existing highly active antiretroviral therapy (HAART) effectively controls viral replication in human immunodeficiency virus type 1 (HIV-1) infected individuals but cannot completely eradicate the infection, at least in part due to the persistence of latently infected cells. One strategy that is being actively pursued to eliminate the latent aspect of HIV-1 infection involves therapies combining latency antagonists with HAART. However, discordant pharmacokinetics between these types of drugs can potentially create sites of active viral replication within certain tissues that might be impervious to HAART. Results A preliminary reverse genetic screen indicated that the proteasome might be involved in the maintenance of the latent state. This prompted testing to determine the effects of proteasome inhibitors (PIs) on latently infected cells. Experiments demonstrated that PIs effectively activated latent HIV-1 in several model systems, including primary T cell models, thereby defining PIs as a new class of HIV-1 latency antagonists. Expanding upon experiments from previous reports, it was also confirmed that PIs inhibit viral replication. Moreover, it was possible to show that PIs act as bifunctional antagonists of HIV-1. The data indicate that PIs activate latent provirus and subsequently decrease viral titers and promote the production of defective virions from activated cells. Conclusions These results represent a proof-of-concept that bifunctional antagonists of HIV-1 can be developed and have the capacity to ensure precise tissue overlap of anti-latency and anti-replication functions, which is of significant importance in the consideration of future drug therapies aimed at viral clearance. PMID:24156270

  12. Cobalt Selenide Nanostructures: An Efficient Bifunctional Catalyst with High Current Density at Low Coverage.

    PubMed

    Masud, Jahangir; Swesi, Abdurazag T; Liyanage, Wipula P R; Nath, Manashi

    2016-07-13

    Electrodeposited Co7Se8 nanostructures exhibiting flake-like morphology show bifunctional catalytic activity for oxygen evolution and hydrogen evolution reaction (OER and HER, respectively) in alkaline medium with long-term durability (>12 h) and high Faradaic efficiency (99.62%). In addition to low Tafel slope (32.6 mV per decade), the Co7Se8 OER electrocatalyst also exhibited very low overpotential to achieve 10 mA cm(-2) (0.26 V) which is lower than other transition metal chalcogenide based OER electrocatalysts reported in the literature and significantly lower than the state-of-the-art precious metal oxides. A low Tafel slope (59.1 mV per decade) was also obtained for the HER catalytic activity in alkaline electrolyte. The OER catalytic activity could be further improved by creating arrays of 3-dimensional rod-like and tubular structures of Co7Se8 through confined electrodeposition on lithographically patterned nanoelectrodes. Such arrays of patterned nanostructures produced exceptionally high mass activity and gravimetric current density (∼68 000 A g(-1)) compared to the planar thin films (∼220 A g(-1)). Such high mass activity of the catalysts underlines reduction in usage of the active material without compromising efficiency and their practical applicability. The catalyst layer could be electrodeposited on different substrates, and an effect of the substrate surface on the catalytic activity was also investigated. The Co7Se8 bifunctional catalyst enabled water electrolysis in alkaline solution at a cell voltage of 1.6 V. The electrodeposition works with exceptional reproducibility on any conducting substrate and shows unprecedented catalytic performance especially with the patterned growth of catalyst rods and tubes. PMID:27309595

  13. Luminomagnetic bifunctionality of Mn2+-bonded graphene oxide/reduced graphene oxide two dimensional nanosheets

    NASA Astrophysics Data System (ADS)

    Amandeep; Kedawat, Garima; Kumar, Pawan; Anshul, Avaneesh; Deshmukh, Abhay D.; Singh, Om Pal; Gupta, R. K.; Amritphale, S. S.; Gupta, Govind; Singh, V. N.; Gupta, Bipin Kumar

    2015-07-01

    Herein, we report the luminomagnetic bifunctional properties of two-dimensional (2D) Mn2+ bonded graphene oxide (GO)/reduced graphene oxide (RGO) nanosheets synthesized using a facile route of oxidation followed by a solvothermal reduction method. Photoluminescence (PL) studies (excited by different wavelengths) revealed that the resonant energy transfer between Mn2+ and sp3/sp2 clusters of GO/RGO is responsible for the enhancement of emissions. Moreover, pH-sensitive PL behaviors have also been investigated in detail. The ferromagnetic behavior is believed to arise due to defects in Mn2+ bonded GO composites. Thus, present reduction method provides a direct route to tune and enhance the optical properties of GO and RGO nanosheets bonded with Mn2+ ions, which creates an opportunity for various technological applications.Herein, we report the luminomagnetic bifunctional properties of two-dimensional (2D) Mn2+ bonded graphene oxide (GO)/reduced graphene oxide (RGO) nanosheets synthesized using a facile route of oxidation followed by a solvothermal reduction method. Photoluminescence (PL) studies (excited by different wavelengths) revealed that the resonant energy transfer between Mn2+ and sp3/sp2 clusters of GO/RGO is responsible for the enhancement of emissions. Moreover, pH-sensitive PL behaviors have also been investigated in detail. The ferromagnetic behavior is believed to arise due to defects in Mn2+ bonded GO composites. Thus, present reduction method provides a direct route to tune and enhance the optical properties of GO and RGO nanosheets bonded with Mn2+ ions, which creates an opportunity for various technological applications. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr01095k

  14. Preparation of Ga-67 labeled monoclonal antibodies using deferoxamine as a bifunctional chelating agent

    SciTech Connect

    Endo, K.; Furukawa, T.; Ohmomo, Y.; Sakahara, H.; Ohta, H.; Nakashima, T.; Okada, K.; Yoshida, O.; Yokoyama, A.; Torizuka, K.

    1984-01-01

    Ga-67 labeled monoclonal IgG or F(ab')/sub 2/ fragments against ..cap alpha..-fetoprotein and ..beta..-subunit of human choriogonadotropin (HCG), were prepared using Deferoxamine (DFO) as a bifunctional chelating agent. DFO, a well-known iron chelating agent, was conjugated with monoclonal antibodies (Ab) by a glutaraldehyde two step method and the effect of conjugation on the Ab activities was examined by RIA and Scatchard plot analysis. In both monoclonal Ab preparations, the conjugation reaction was favored as the pH increased. However, Ab-binding activities decreased as the molecular ratios of DFO to Ab increased. Preserved Ab activities were observed when Ab contained DFO per Ab molecule less than 2.1. At a ratio of over 3.3 DFO molecules per Ab, the maximal binding capacity rather than the affinity constant decreased. The inter-molecular cross linkage seemed to be responsible for the deactivation of binding activities. The obtained DFO-Ab conjugates, were then easily labeled with high efficiency and reproducibility and Ga-67 DFO-Ab complexes were highly stable both in vitro and in vivo. Thus, biodistribution of Ga-67 labeled F(ab')/sub 2/ fragments of monoclonal Ab to HCG ..beta..-subunit was attempted in nude mice transplanted with HCG-producing human teratocarcinoma. Tumor could be visualized, in spite of relatively high background imaging of liver, kidney and spleen. The use of DFO as a bifunctional chelating agent provided good evidence for its applicability to labeling monoclonal Ab with almost full retention of Ab activities. Further, availability of Ga-68 will make Ga-68 DFO-monoclonal Ab a very useful tool for positron tomography imaging of various tumors.

  15. Synthesis and Evaluation of New Generation Cross-Bridged Bifunctional Chelator for (64)Cu Radiotracers.

    PubMed

    Dale, Ajit V; An, Gwang Il; Pandya, Darpan N; Ha, Yeong Su; Bhatt, Nikunj; Soni, Nisarg; Lee, Hochun; Ahn, Heesu; Sarkar, Swarbhanu; Lee, Woonghee; Huynh, Phuong Tu; Kim, Jung Young; Gwon, Mi-Ri; Kim, Sung Hong; Park, Jae Gyu; Yoon, Young-Ran; Yoo, Jeongsoo

    2015-09-01

    Bifunctional chelators have been successfully used to construct (64)Cu-labeled radiopharmaceuticals. Previously reported chelators with cross-bridged cyclam backbones have various essential features such as high stability of the copper(II) complex, high efficiency of radiolabeling at room temperature, and good biological inertness of the radiolabeled complex, along with rapid body clearance. Here, we report a new generation propylene-cross-bridged chelator with hybrid acetate/phosphonate pendant groups (PCB-TE1A1P) developed with the aim of combining these key properties in a single chelator. The PCB-TE1A1P was synthesized from cyclam with good overall yield. The Cu(II) complex of our chelator showed good robustness in kinetic stability evaluation experiments, such as acidic decomplexation and cyclic voltammetry studies. The Cu(II) complex of PCB-TE1A1P remained intact under highly acidic conditions (12 M HCl, 90 °C) for 8 d and showed quasi-reversible reduction/oxidation peaks at -0.77 V in electrochemical studies. PCB-TE1A1P was successfully radiolabeled with (64)Cu ions in an acetate buffer at 60 °C within 60 min. The electrophoresis study revealed that the (64)Cu-PCB-TE1A1P complex has net negative charge in aqueous solution. The biodistribution and in vivo stability study profiles of (64)Cu-PCB-TE1A1P indicated that the radioactive complex was stable under physiological conditions and cleared rapidly from the body. A whole body positron emission tomography (PET) imaging study further confirmed high in vivo stability and fast clearance of the complex in mouse models. In conclusion, PCB-TE1A1P has good potential as a bifunctional chelator for (64)Cu-based radiopharmaceuticals, especially those involving peptides. PMID:26286436

  16. 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.

  17. Mitigation of nitrogen mustard mediated skin injury by a novel indomethacin bifunctional prodrug.

    PubMed

    Composto, Gabriella M; Laskin, Jeffrey D; Laskin, Debra L; Gerecke, Donald R; Casillas, Robert P; Heindel, Ned D; Joseph, Laurie B; Heck, Diane E

    2016-06-01

    Nitrogen mustard (NM) is a bifunctional alkylating agent that is highly reactive in the skin causing extensive tissue damage and blistering. In the present studies, a modified cutaneous murine patch model was developed to characterize NM-induced injury and to evaluate the efficacy of an indomethacin pro-drug in mitigating toxicity. NM (20μmol) or vehicle control was applied onto 6mm glass microfiber filters affixed to the shaved dorsal skin of CD-1 mice for 6min. This resulted in absorption of approximately 4μmol of NM. NM caused localized skin damage within 1 d, progressing to an eschar within 2-3 d, followed by wound healing after 4-5 d. NM-induced injury was associated with increases in skin thickness, inflammatory cell infiltration, reduced numbers of sebocytes, basal keratinocyte double stranded DNA breaks, as measured by phospho-histone 2A.X expression, mast cell degranulation and increases in inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2). Wound healing was characterized by epidermal hyperplasia and marked increases in basal cells expressing proliferating cell nuclear antigen. A novel indomethacin-anticholinergic prodrug (4338) designed to target cyclooxygenases and acetylcholinesterase (AChE), was found to markedly suppress NM toxicity, decreasing wound thickness and eschar formation. The prodrug also inhibited mast cell degranulation, suppressed keratinocyte expression of iNOS and COX-2, as well as markers of epidermal proliferation. These findings indicate that a novel bifunctional pro-drug is effective in limiting NM mediated dermal injury. Moreover, our newly developed cutaneous patch model is a sensitive and reproducible method to assess the mechanism of action of countermeasures. PMID:27189522

  18. Dimerization and Bifunctionality Confer Robustness to the Isocitrate Dehydrogenase Regulatory System in Escherichia coli*

    PubMed Central

    Dexter, Joseph P.; Gunawardena, Jeremy

    2013-01-01

    An important goal of systems biology is to develop quantitative models that explain how specific molecular features give rise to systems-level properties. Metabolic and regulatory pathways that contain multifunctional proteins are especially interesting to study from this perspective because they have frequently been observed to exhibit robustness: the ability for a system to perform its proper function even as levels of its components change. In this study, we use extensive biochemical data and algebraic modeling to develop and analyze a model that shows how robust behavior arises in the isocitrate dehydrogenase (IDH) regulatory system of Escherichia coli, which was shown in 1985 to experimentally exhibit robustness. E. coli IDH is regulated by reversible phosphorylation catalyzed by the bifunctional isocitrate dehydrogenase kinase/phosphatase (IDHKP), and the level of IDH activity determines whether carbon flux is directed through the glyoxylate bypass (for growth on two-carbon substrates) or the full tricarboxylic acid cycle. Our model, which incorporates recent structural data on IDHKP, identifies several specific biochemical features of the system (including homodimerization of IDH and bifunctionality of IDHKP) that provide a potential explanation for robustness. Using algebraic techniques, we derive an invariant that summarizes the steady-state relationship between the phospho-forms of IDH. We use the invariant in combination with kinetic data on IDHKP to calculate IDH activity at a range of total IDH levels and find that our model predicts robustness. Our work unifies much of the known biochemistry of the IDH regulatory system into a single quantitative framework and highlights the importance of constructing biochemically realistic models in systems biology. PMID:23192354

  19. Investigations of a bearing fault detector for railroad bearings

    NASA Technical Reports Server (NTRS)

    Wilson, D. S.; Frarey, J. L.

    1975-01-01

    The laboratory tests are described which were conducted on new and damaged bearings to determine the feasibility of using high-frequency vibration as a diagnostic tool. A high-frequency band pass filter and demodulator was assembled to permit field measurements of the high-frequency vibrations. Field tests were conducted on an actual truck and on an axle assembly run in a grease test rig. These field tests were directed toward demonstration of the suitability and capabilities of the high-frequency technique for field application. Two specific areas of field application were identified as being cost effective for railroad use. One area is the examination of railroad roller bearings at a derailment site, and the second is as a wayside detector to supplement present hot box detectors for defective roller bearings.

  20. Space Shuttle Body Flap Actuator Bearing Testing For NASA Return to Flight

    NASA Technical Reports Server (NTRS)

    Jett, Timothy R.; Thom, Robert L.; Moore, Lewis E.; Gibson, Howard G.; Hall, Phillip B.; Predmore, Roamer E.

    2005-01-01

    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 actuatols 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 has been completed, and results indicate the previously flown bearings are acceptable for up to 12 additional missions.

  1. 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

    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.

  2. 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.

  3. Hydrostatic bearings for a turbine fluid flow metering device

    DOEpatents

    Fincke, James R.

    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.

  4. Cryogenic Magnetic Bearing Test Facility (CMBTF)

    NASA Technical Reports Server (NTRS)

    1992-01-01

    The Cryogenic Magnetic Bearing Test Facility (CMBTF) was designed and built to evaluate compact, lightweight magnetic bearings for use in the SSME's (space shuttle main engine) liquid oxygen and liquid hydrogen turbopumps. State of the art and tradeoff studies were conducted which indicated that a hybrid permanent magnet bias homopolar magnetic bearing design would be smaller, lighter, and much more efficient than conventional industrial bearings. A test bearing of this type was designed for the test rig for use at both room temperature and cryogenic temperature (-320 F). The bearing was fabricated from state-of-the-art materials and incorporated into the CMBTF. Testing at room temperature was accomplished at Avcon's facility. These preliminary tests indicated that this magnetic bearing is a feasible alternative to older bearing technologies. Analyses showed that the hybrid magnetic bearing is one-third the weight, considerably smaller, and uses less power than previous generations of magnetic bearings.

  5. Application of foil bearings to helium turbocompressor

    SciTech Connect

    Chen, H.Ming; Howarth, R.; Bernard, Geren; Theilacker, Jay C.; Soyars, William M.; /Fermilab

    2001-01-01

    Hydrodynamic gas-lubricated foil bearings are ideal for machinery that operates at high speed or in extreme-temperature environments. As motors and generators run at higher speeds with more torque capacity, the need for commonly available, robust, high-speed, low-loss foil bearings is clear. This paper presents an application example of the successful replacement of a tape-type bearing for a bump-type bearing in a helium turbocompressor. Both bearing types are described, as are the steps involved in design and fabrication of the bump bearing, and results of comparison tests between the original and replacement bearings. Methods to analyze bump-type foil bearings with commercially available software are reviewed to further emphasize the inherent simplicity of these bearings. By providing the engineering community with the understanding needed to successfully apply foil bearings, the authors hope that the benefits and true potential of this technology will finally be realized.

  6. 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.

  7. 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

  8. [Controlled weight bearing after osteosynthesis].

    PubMed

    Perren, T; Matter, P

    1993-01-01

    Patient compliance with postoperative partial weight bearing can be a difficult management problem. The problem may be intentional or unintentional. There is no objective way to assess the amount of weight placed on the lower extremity by the patient. It is our clinical suspicion that patients place more weight than is desirable on the effected limb. There are few reports in the literature on this topic. One study has confirmed our suspicion of poor patient compliance with postoperative weight bearing. Our goal is to develop a system to accurately assess weight bearing and to improve this aspect of postoperative fracture care. Through an active feedback device we hope to improve patient education and understanding. We plan to study the clinical applications of using a pressure sensitive shoe insert device. Our ultimate goal is to improve upon the present device and to study the clinical application of there use. PMID:8123330

  9. '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.

  10. 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

  11. The Role of Radial Clearance on the Performance of Foil Air Bearings

    NASA Technical Reports Server (NTRS)

    Radil, Kevin; Howard, Samuel; Dykas, Brian

    2002-01-01

    Load capacity tests were conducted to determine how radial clearance variations affect the load capacity coefficient of foil air bearings. Two Generation III foil air bearings with the same design but possessing different initial radial clearances were tested at room temperature against an as-ground PS304 coated journal operating at 30,000 rpm. Increases in radial clearance were accomplished by reducing the journal's outside diameter via an in-place grinding system. From each load capacity test the bearing load capacity coefficient was calculated from the rule-of-thumb (ROT) model developed for foil air bearings. The test results indicate that, in terms of the load capacity coefficient, radial clearance has a direct impact on the performance of the foil air bearing. Each test bearing exhibited an optimum radial clearance that resulted in a maximum load capacity coefficient. Relative to this optimum value are two separate operating regimes that are governed by different modes of failure. Bearings operating with radial clearances less than the optimum exhibit load capacity coefficients that are a strong function of radial clearance and are prone to a thermal runaway failure mechanism and bearing seizure. Conversely, a bearing operating with a radial clearance twice the optimum suffered only a 20 percent decline in its maximum load capacity coefficient and did not experience any thermal management problems. However, it is unknown to what degree these changes in radial clearance had on other performance parameters, such as the stiffness and damping properties of the bearings.

  12. Air bearing vacuum seal assembly

    DOEpatents

    Booth, Rex

    1978-01-01

    An air bearing vacuum seal assembly capable of rotating at the speed of several thousand revolutions per minute using an air cushion to prevent the rotating and stationary parts from touching, and a two stage differential pumping arrangement to maintain the pressure gradient between the air cushion and the vacuum so that the leak rate into the vacuum is, for example, less than 1 .times. 10.sup.-4 Pa m.sup.3 /s. The air bearing vacuum seal has particular application for mounting rotating targets to an evacuated accelerator beam tube for bombardment of the targets with high-power charged particle beams in vacuum.

  13. 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

  14. 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

  15. A novel bifunctional histone protein in Streptomyces: a candidate for structural coupling between DNA conformation and transcription during development and stress?

    PubMed Central

    Aldridge, Matthew; Facey, Paul; Francis, Lewis; Bayliss, Sion; Del Sol, Ricardo; Dyson, Paul

    2013-01-01

    Antibiotic-producing Streptomyces are complex bacteria that remodel global transcription patterns and their nucleoids during development. Here, we describe a novel developmentally regulated nucleoid-associated protein, DdbA, of the genus that consists of an N-terminal DNA-binding histone H1-like domain and a C-terminal DksA-like domain that can potentially modulate RNA polymerase activity in conjunction with ppGpp. Owing to its N-terminal domain, the protein can efficiently bind and condense DNA in vitro. Loss of function of this DNA-binding protein results in changes in both DNA condensation during development and the ability to adjust DNA supercoiling in response to osmotic stress. Initial analysis of the DksA-like activity of DdbA indicates that overexpression of the protein suppresses a conditional deficiency in antibiotic production of relA mutants that are unable to synthesise ppGpp, just as DksA overexpression in Escherichia coli can suppress ppGpp0 phenotypes. The null mutant is also sensitive to oxidative stress owing to impaired upregulation of transcription of sigR, encoding an alternative sigma factor. Consequently, we propose this bifunctional histone-like protein as a candidate that could structurally couple changes in DNA conformation and transcription during the streptomycete life-cycle and in response to stress. PMID:23525459

  16. MnCo2O4 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

  17. Seasonal carbohydrate storage and mobilization in bearing and non-bearing pistachio (Pistacia vera) trees.

    PubMed

    Spann, Timothy M; Beede, Robert H; Dejong, Theodore M

    2008-02-01

    We analyzed annual carbohydrate storage and mobilization of bearing ("on") and non-bearing ("off") 'Kerman' pistachio (Pistacia vera L.) trees growing on three different rootstocks. On all rootstocks, carbohydrate storage in shoots and branches of "on" and "off" trees was lowest following the spring growth flush. In "off" trees, stored carbohydrates increased and remained high after the initial growth flush. In "on" trees, stem carbohydrates increased temporarily in early summer, but were mobilized in mid-season during kernel fill, and then increased again after nut harvest. During the dormant season, the only substantial differences in carbohydrate storage between previously "on" and "off" trees were found in the roots of the weakest rootstock. The annual carbohydrate storage and mobilization pattern in canopy branches of heavily cropped pistachio trees appeared to be driven by carbohydrate demands related to nut development and untempered by tree vigor. Mobilization of carbohydrates from current-season and 1- and 2-year-old stem wood of "on" trees during the primary period of kernel fill corresponded with the period of inflorescence bud abscission. Thus, the alternate bearing pattern associated with inflorescence bud abscission in 'Kerman' pistachio may be a function of mid-season mobilization of stored carbohydrates in current-season stems resulting in stimulation of inflorescence bud abscission. PMID:18055431

  18. Purification, crystallization and preliminary X-ray crystallographic analysis of rice bifunctional α-amylase/subtilisin inhibitor from Oryza sativa

    SciTech Connect

    Lin, Yi-Hung; Peng, Wen-Yan; Huang, Yen-Chieh; Guan, Hong-Hsiang; Hsieh, Ying-Cheng; Liu, Ming-Yih; Chang, Tschining; Chen, Chun-Jung

    2006-08-01

    The crystallization of rice α-amylase/subtilisin bifunctional inhibitor is reported. Rice bifunctional α-amylase/subtilisin inhibitor (RASI) can inhibit both α-amylase from larvae of the red flour beetle (Tribolium castaneum) and subtilisin from Bacillus subtilis. The synthesis of RASI is up-regulated during the late milky stage in developing seeds. The 8.9 kDa molecular-weight RASI from rice has been crystallized using the hanging-drop vapour-diffusion method. According to 1.81 Å resolution X-ray diffraction data from rice RASI crystals, the crystal belongs to space group P2{sub 1}2{sub 1}2, with unit-cell parameters a = 79.99, b = 62.95, c = 66.70 Å. Preliminary analysis indicates two RASI molecules in an asymmetric unit with a solvent content of 44%.

  19. Spinel Mn-Co oxide in N-doped carbon nanotubes as a bifunctional electrocatalyst synthesized by oxidative cutting.

    PubMed

    Zhao, Anqi; Masa, Justus; Xia, Wei; Maljusch, Artjom; Willinger, Marc-Georg; Clavel, Guylhaine; Xie, Kunpeng; Schlögl, Robert; Schuhmann, Wolfgang; Muhler, Martin

    2014-05-28

    The notorious instability of non-precious-metal catalysts for oxygen reduction and evolution is by far the single unresolved impediment for their practical applications. We have designed highly stable and active bifunctional catalysts for reversible oxygen electrodes by oxidative thermal scission, where we concurrently rupture nitrogen-doped carbon nanotubes and oxidize Co and Mn nanoparticles buried inside them to form spinel Mn-Co oxide nanoparticles partially embedded in the nanotubes. Impressively high dual activity for oxygen reduction and evolution is achieved using these catalysts, surpassing those of Pt/C, RuO2, and IrO2 and thus raising the prospect of functional low-cost, non-precious-metal bifunctional catalysts in metal-air batteries and reversible fuel cells, among others, for a sustainable and green energy future. PMID:24815686

  20. N,P-Codoped Carbon Networks as Efficient Metal-free Bifunctional Catalysts for Oxygen Reduction and Hydrogen Evolution Reactions.

    PubMed

    Zhang, Jintao; Qu, Liangti; Shi, Gaoquan; Liu, Jiangyong; Chen, Jianfeng; Dai, Liming

    2016-02-01

    The high cost and scarcity of noble metal catalysts, such as Pt, have hindered the hydrogen production from electrochemical water splitting, the oxygen reduction in fuel cells and batteries. Herein, we developed a simple template-free approach to three-dimensional porous carbon networks codoped with nitrogen and phosphorus by pyrolysis of a supermolecular aggregate of self-assembled melamine, phytic acid, and graphene oxide (MPSA/GO). The pyrolyzed MPSA/GO acted as the first metal-free bifunctional catalyst with high activities for both oxygen reduction and hydrogen evolution. Zn-air batteries with the pyrolyzed MPSA/GO air electrode showed a high peak power density (310 W g(-1) ) and an excellent durability. Thus, the pyrolyzed MPSA/GO is a promising bifunctional catalyst for renewable energy technologies, particularly regenerative fuel cells. PMID:26709954

  1. Vanadium nanobelts coated nickel foam 3D bifunctional electrode with excellent catalytic activity and stability for water electrolysis.

    PubMed

    Yu, Yu; Li, Pei; Wang, Xiaofang; Gao, Wenyu; Shen, Zongxu; Zhu, Yanan; Yang, Shuliang; Song, Weiguo; Ding, Kejian

    2016-05-19

    Pursuit of highly active, stable and low-cost electrocatalysts for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) is the key point for large-scale water splitting. A vanadium nanobelts coating on a nickel foam (V/NF) is proposed as an excellent 3D bifunctional electrode for water electrolysis here, which exhibits high activities with overpotentials of 292 and 176 mV at 10 mA cm(-2) for OER and HER, respectively. When employed as a bifunctional electrocatalyst in an alkaline water electrolyzer, a cell voltage of 1.80 V was required to achieve 20 mA cm(-2) with a slight increase during a 24 h durability test. The existence of the appropriate amount of nitrogen and oxygen elements in the surface region of vanadium nanobelts is regarded to be responsible for the electrocatalytic activity. PMID:27152646

  2. MOFs as multifunctional catalysts: one-pot synthesis of menthol from citronellal over a bifunctional MIL-101 catalyst.

    PubMed

    Cirujano, F G; Llabrés i Xamena, F X; Corma, A

    2012-04-14

    A bifunctional MOF catalyst containing coordinatively unsaturated Cr(3+) sites and palladium nanoparticles (Pd@MIL-101) has been used for the cyclization of citronellal to isopulegol and for the one-pot tandem isomerization/hydrogenation of citronellal to menthol. The MOF was found to be stable under the reaction conditions used, and the results obtained indicate that the performance of this bifunctional solid catalyst is comparable with other state-of-the-art materials for the tandem reaction: Full citronellal conversion was attained over Pd@MIL-101 in 18 h, with 86% selectivity to menthols and a diastereoselectivity of 81% to the desired (-)-menthol, while up to 30 h were necessary for attaining similar values over Ir/H-beta under analogous reaction conditions. PMID:22382815

  3. 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, β-cell differentiation, normal β-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

  4. Dual-Doped Molybdenum Trioxide Nanowires: A Bifunctional Anode for Fiber-Shaped Asymmetric Supercapacitors and Microbial Fuel Cells.

    PubMed

    Yu, Minghao; Cheng, Xinyu; Zeng, Yinxiang; Wang, Zilong; Tong, Yexiang; Lu, Xihong; Yang, Shihe

    2016-06-01

    A novel in situ N and low-valence-state Mo dual doping strategy was employed to significantly improve the conductivity, active-site accessibility, and electrochemical stability of MoO3 , drastically boosting its electrochemical properties. Consequently, our optimized N-MoO3-x nanowires exhibited exceptional performances as a bifunctional anode material for both fiber-shaped asymmetric supercapacitors (ASCs) and microbial fuel cells (MFCs). The flexible fiber-shaped ASC and MFC device based on the N-MoO3-x anode could deliver an unprecedentedly high energy density of 2.29 mWh cm(-3) and a remarkable power density of 0.76 μW cm(-1) , respectively. Such a bifunctional fiber-shaped N-MoO3-x electrode opens the way to integrate the electricity generation and storage for self-powered sources. PMID:27097987

  5. EXCITATION OF STRUCTURAL RESONANCE DUE TO A BEARING FAILURE

    SciTech Connect

    Leishear, R; David Stefanko, D

    2007-04-30

    Vibration due to a bearing failure in a pump created significant vibrations in a fifteen foot by fifteen foot by eight feet tall mounting platform due to excitation of resonant frequencies. In this particular application, an 18,000 pound pump was mounted to a structural steel platform. When bearing damage commenced, the platform vibrated with sufficient magnitude that conversations could not be heard within forty feet of the pump. Vibration analysis determined that the frequency of the bearing was coincident to one of the natural frequencies of the pump, which was, in turn, coincident to one of the natural frequencies of the mounting platform. This coincidence of frequencies defines resonance. Resonance creates excessive vibrations when the natural frequency of a structure is coincident to an excitation frequency. In this well documented case, the excitation frequency was related to ball bearing failures. The pump is a forty foot long vertical pump used to mix nuclear waste in 1,300,000 gallon tanks. A 300 horsepower drive motor is mounted to a structural steel platform on top of the tank. The pump hangs down into the tank from above to mix the waste and is inaccessible after installation. Initial awareness of the problem was due to increased noise from the pump. Initial vibration analysis indicated that the vibration levels of the bearing were within the expected range for this type of bearing, and the resonant condition was not obvious. Further analysis consisted of disassembly of the motor to inspect the bearings and extensive vibration monitoring. Vibration data for the bearings was obtained from the manufacturer and compared to measured vibration plots for the pump and mounting platform. Vibration data measured along the length of the pump was available from full scale testing, and vibrations were also measured at the installed pump. One of the axial frequencies of the pump, the platform frequency in the vertical direction, and the ball spin frequency for the

  6. Vibrations of Hybrid Ceramic Ball Bearings

    NASA Astrophysics Data System (ADS)

    Ohta, H.; Kobayashi, K.

    1996-05-01

    Hybrid ceramic ball bearings with silicone nitride balls and steel rings were tested, and the vibration characteristics were compared with those of conventional steel ball bearings. In this study, two types of hybrid ceramic ball bearings and two types of conventional steel ball bearings were used as test bearings. The test bearings were operated under several rotational speeds and axial loads. The radial and the axial vibrations on the outer ring of each test bearing were detected by an accelerometer. The vibrations were examined by using an FFT analyzer. From the experimental results, analysis and discussion, the vibration characteristics of hybrid ceramic ball bearings, compared with those of conventional steel ball bearings, are explained.

  7. 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.

  8. Wave Journal Bearing. Part 1: Analysis

    NASA Technical Reports Server (NTRS)

    Dimofte, Florin

    1995-01-01

    A wave journal bearing concept features a waved inner bearing diameter of the non-rotating bearing side and it is an alternative to the plain journal bearing. The wave journal bearing has a significantly increased load capacity in comparison to the plain journal bearing operating at the same eccentricity. It also offers greater stability than the plain circular bearing under all operating conditions. The wave bearing's design is relatively simple and allows the shaft to rotate in either direction. Three wave bearings are sensitive to the direction of an applied stationary side load. Increasing the number of waves reduces the wave bearing's sensitivity to the direction of the applied load relative to the wave. However, the range in which the bearing performance can be varied decreases as the number of waves increases. Therefore, both the number and the amplitude of the waves must be properly selected to optimize the wave bearing design for a specific application. It is concluded that the stiffness of an air journal bearing, due to hydrodynamic effect, could be doubled and made to run stably by using a six or eight wave geometry with a wave amplitude approximately half of the bearing radial clearance.

  9. Synthesis, characterization, and evaluation of a novel bifunctional chelating agent for the lead isotopes 203Pb and 212Pb.

    PubMed

    Chappell, L L; Dadachova, E; Milenic, D E; Garmestani, K; Wu, C; Brechbiel, M W

    2000-01-01

    Radioisotopes of Pb(II) have been of some interest in radioimmunotherapy and radioimmunoimaging (RII). However, the absence of a kinetically stable bifunctional chelating agent for Pb(II) has hampered its use for these applications. 203Pb (T(1/2) = 52.02 h) has application potential in RII, with a gamma-emission that is ideal for single photon emission computerized tomography, whereas 212Pb (T(1/2) = 10 h) is a source of highly cytotoxic alpha-particles via its decay to its 212Bi (T(1/2) = 60 min) daughter. The synthesis of the novel bifunctional chelating agent 2-(4-isothiocyanotobenzyl)-1,4,7,10-tetraaza-1,4,7,10-tetra- (2-carbamoyl methyl)-cyclododecane (4-NCS-Bz-TCMC) is reported herein. The Pb[TCMC]2+ complex was less labile to metal ion release than Pb[DOTA]2- at pH 3.5 and below in isotopic exchange experiments. In addition to increased stability to Pb2+ ion release at low pH, the bifunctional TCMC ligand was found to have many other advantages over the bifunctional 1,4,7,10-tetraazacyclodocane-1,4,7,10-tetraacetic acid (DOTA) ligand. These include a shorter and more straightforward synthetic route, a more efficient conjugation reaction to a monoclonal antibody (mAb), with a higher chelate to protein ratio, a higher percent immuroreactivity, and a more efficient radiolabeling reaction of the mAb-ligand conjugate with 203Pb. PMID:10755652

  10. Synergistic bifunctional catalyst design based on perovskite oxide nanoparticles and intertwined carbon nanotubes for rechargeable zinc-air battery applications.

    PubMed

    Lee, Dong Un; Park, Hey Woong; Park, Moon Gyu; Ismayilov, Vugar; Chen, Zhongwei

    2015-01-14

    Advanced morphology of intertwined core-corona structured bifunctional catalyst (IT-CCBC) is introduced where perovskite lanthanum nickel oxide nanoparticles (LaNiO3 NP) are encapsulated by high surface area network of nitrogen-doped carbon nanotubes (NCNT) to produce highly active and durable bifunctional catalyst for rechargeable metal-air battery applications. The unique composite morphology of IT-CCBC not only enhances the charge transport property by providing rapid electron-conduction pathway but also facilitates in diffusion of hydroxyl and oxygen reactants through the highly porous framework. Confirmed by electrochemical half-cell testing, IT-CCBC in fact exhibits very strong synergy between LaNiO3 NP and NCNT demonstrating bifunctionality with significantly improved catalytic activities of oxygen reduction reaction (ORR) and oxygen evolution reaction (OER). Furthermore, when compared to the state-of-art catalysts, IT-CCBC outperforms Pt/C and Ir/C in terms of ORR and OER, respectively, and shows improved electrochemical stability compared to them after cycle degradation testing. The practicality of the catalyst is corroborated by testing in a realistic rechargeable zinc-air battery utilizing atmospheric air in ambient conditions, where IT-CCBC demonstrates superior charge and discharge voltages and long-term cycle stability with virtually no battery voltage fading. These improved electrochemical properties of the catalyst are attributed to the nanosized dimensions of LaNiO3 NP controlled by simple hydrothermal technique, which enables prolific growth of and encapsulation by highly porous NCNT network. The excellent electrochemical results presented in this study highlight IT-CCBC as highly efficient and commercially viable bifunctional catalyst for rechargeable metal-air battery applications. PMID:25494945

  11. Highly active and durable core-corona structured bifunctional catalyst for rechargeable metal-air battery application.

    PubMed

    Chen, Zhu; Yu, Aiping; Higgins, Drew; Li, Hui; Wang, Haijiang; Chen, Zhongwei

    2012-04-11

    A new class of core-corona structured bifunctional catalyst (CCBC) consisting of lanthanum nickelate centers supporting nitrogen-doped carbon nanotubes (NCNT) has been developed for rechargeable metal-air battery application. The nanostructured design of the catalyst allows the core and corona to catalyze the oxygen evolution reaction (OER) and oxygen reduction reaction (ORR), respectively. These materials displayed exemplary OER and ORR activity through half-cell testing, comparable to state of the art commercial lanthanum nickelate (LaNiO(3)) and carbon-supported platinum (Pt/C), with added bifunctional capabilities allowing metal-air battery rechargeability. LaNiO(3) and Pt/C are currently the most accepted benchmark electrocatalyst materials for the OER and ORR, respectively; thus with comparable activity toward both of these reactions, CCBC are presented as a novel, inexpensive catalyst component for the cathode of rechargeable metal-air batteries. Moreover, after full-range degradation testing (FDT) CCBC retained excellent activity, retaining 3 and 13 times greater ORR and OER current upon comparison to state of the art Pt/C. Zinc-air battery performances of CCBC is in good agreement with the half-cell experiments with this bifunctional electrocatalyst displaying high activity and stability during battery discharge, charge, and cycling processes. Owing to its outstanding performance toward both the OER and ORR, comparable with the highest performing commercial catalysts to date for each of the respective reaction, coupled with high stability and rechargeability, CCBC is presented as a novel class of bifunctional catalyst material that is very applicable to future generation rechargeable metal-air batteries. PMID:22372510

  12. Dynamic Kinetic Resolution of Biaryl Lactones via a Chiral Bifunctional Amine Thiourea-Catalyzed Highly Atropo-enantioselective Transesterification.

    PubMed

    Yu, Chenguang; Huang, He; Li, Xiangmin; Zhang, Yueteng; Wang, Wei

    2016-06-01

    A solution to the unmet synthetic challenge of achieving highly atropo-enantioselective transesterification of Bringmann's lactones has been realized, employing a chiral bifunctional amine thiourea as promoter. The synergistic activation of the lactones and alcohols/phenols by the respective thiourea and amine groups is crucial for achieving the highly enantioselective, high-yielding dynamic kinetic resolution process. This protocol gives highly optically pure, axially chiral biaryl compounds with a broad substrate scope under mild reaction conditions. PMID:27218264

  13. Vanadium nanobelts coated nickel foam 3D bifunctional electrode with excellent catalytic activity and stability for water electrolysis

    NASA Astrophysics Data System (ADS)

    Yu, Yu; Li, Pei; Wang, Xiaofang; Gao, Wenyu; Shen, Zongxu; Zhu, Yanan; Yang, Shuliang; Song, Weiguo; Ding, Kejian

    2016-05-01

    Pursuit of highly active, stable and low-cost electrocatalysts for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) is the key point for large-scale water splitting. A vanadium nanobelts coating on a nickel foam (V/NF) is proposed as an excellent 3D bifunctional electrode for water electrolysis here, which exhibits high activities with overpotentials of 292 and 176 mV at 10 mA cm-2 for OER and HER, respectively. When employed as a bifunctional electrocatalyst in an alkaline water electrolyzer, a cell voltage of 1.80 V was required to achieve 20 mA cm-2 with a slight increase during a 24 h durability test. The existence of the appropriate amount of nitrogen and oxygen elements in the surface region of vanadium nanobelts is regarded to be responsible for the electrocatalytic activity.Pursuit of highly active, stable and low-cost electrocatalysts for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) is the key point for large-scale water splitting. A vanadium nanobelts coating on a nickel foam (V/NF) is proposed as an excellent 3D bifunctional electrode for water electrolysis here, which exhibits high activities with overpotentials of 292 and 176 mV at 10 mA cm-2 for OER and HER, respectively. When employed as a bifunctional electrocatalyst in an alkaline water electrolyzer, a cell voltage of 1.80 V was required to achieve 20 mA cm-2 with a slight increase during a 24 h durability test. The existence of the appropriate amount of nitrogen and oxygen elements in the surface region of vanadium nanobelts is regarded to be responsible for the electrocatalytic activity. Electronic supplementary information (ESI) available: More SEM, TEM images, XRD patterns, LSV curves, XPS spectra. See DOI: 10.1039/c6nr02395a

  14. Iterative Coupling of Two Different Enones by Nitromethane Using Bifunctional Thiourea Organocatalysts. Stereocontrolled Assembly of Cyclic and Acyclic Structures.

    PubMed

    Varga, Szilárd; Jakab, Gergely; Csámpai, Antal; Soós, Tibor

    2015-09-18

    An organocatalytic iterative assembly line has been developed in which nitromethane was sequentially coupled with two different enones using a combination of pseudoenantiomeric cinchona-based thiourea catalysts. Application of unsaturated aldehydes and ketones in the second step of the iterative sequence allows the construction of cyclic syn-ketols and acyclic compounds with multiple contiguous stereocenters. The combination of the multifunctional substrates and ambident electrophiles rendered some organocatalytic transformations possible that have not yet been realized in bifunctional noncovalent organocatalysis. PMID:26301563

  15. Pros and cons of bifunctional platinum(IV) antitumor prodrugs: two are (not always) better than one.

    PubMed

    Gabano, Elisabetta; Ravera, Mauro; Osella, Domenico

    2014-07-14

    This article evaluates the efficacy and applicability of bifunctional prodrugs consisting of a six-coordinate Pt(iv) octahedral core and one or more bioactive molecules. The platinum(iv) complexes release upon reduction the corresponding cytotoxic Pt(ii) agents and the bioactive molecules, able to inhibit some biochemical mechanisms of cancer growth and/or prevent the deactivation of the Pt(ii) metabolites. PMID:24874896

  16. A bifunctional monocyclic beta-lactam cross-links across the active site of beta-lactamase.

    PubMed

    Ahluwalia, R; Day, R A; Nauss, J

    1995-01-17

    A 4-alkoxy-2-azetidinone behaves as a bifunctional active site-directed inhibitor of the class A beta-lactamase from Bacillus cereus 569/H. It cross-links SER 70 and LYS 234 as it binds in a approximately 1:1 ratio. The cross-linked enzyme is irreversibly inhibited while the secondary structure is partially stabilized under conditions when the native enzyme is otherwise converted to a form with no detectable secondary structure by circular dichroism. PMID:7826374

  17. Fuzzy control of magnetic bearings

    NASA Technical Reports Server (NTRS)

    Feeley, J. J.; Niederauer, G. M.; Ahlstrom, D. J.

    1991-01-01

    The use of an adaptive fuzzy control algorithm implemented on a VLSI chip for the control of a magnetic bearing was considered. The architecture of the adaptive fuzzy controller is similar to that of a neural network. The performance of the fuzzy controller is compared to that of a conventional controller by computer simulation.

  18. Inserts Automatically Lubricate Ball Bearings

    NASA Technical Reports Server (NTRS)

    Hager, J. A.

    1983-01-01

    Inserts on ball-separator ring of ball bearings provide continuous film of lubricant on ball surfaces. Inserts are machined or molded. Small inserts in ball pockets provide steady supply of lubricant. Technique is utilized on equipment for which maintenance is often poor and lubrication interval is uncertain, such as household appliances, automobiles, and marine engines.

  19. High performance rolling element bearing

    NASA Technical Reports Server (NTRS)

    Bursey, Jr., Roger W. (Inventor); Olinger, Jr., John B. (Inventor); Owen, Samuel S. (Inventor); Poole, William E. (Inventor); Haluck, David A. (Inventor)

    1993-01-01

    A high performance rolling element bearing (5) which is particularly suitable for use in a cryogenically cooled environment, comprises a composite cage (45) formed from glass fibers disposed in a solid lubricant matrix of a fluorocarbon polymer. The cage includes inserts (50) formed from a mixture of a soft metal and a solid lubricant such as a fluorocarbon polymer.

  20. 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.

  1. Intelligent Engine Systems: Bearing System

    NASA Technical Reports Server (NTRS)

    Singh, Arnant P.

    2008-01-01

    The overall requirements necessary for sensing bearing distress and the related criteria to select a particular rotating sensor were established during the phase I. The current phase II efforts performed studies to evaluate the Robustness and Durability Enhancement of the rotating sensors, and to design, and develop the Built-in Telemetry System concepts for an aircraft engine differential sump. A generic test vehicle that can test the proposed bearing diagnostic system was designed, developed, and built. The Timken Company, who also assisted with testing the GE concept of using rotating sensors for the differential bearing diagnostics during previous phase, was selected as a subcontractor to assist General Electric (GE) for the design, and procurement of the test vehicle. A purchase order was prepared to define the different sub-tasks, and deliverables for this task. The University of Akron was selected to provide the necessary support for installing, and integrating the test vehicle with their newly designed test facility capable of simulating the operating environment for the planned testing. The planned testing with good and damaged bearings will be on hold pending further continuation of this effort during next phase.

  2. Satellite monitoring of black bear.

    NASA Technical Reports Server (NTRS)

    Craighead, J. J.; Craighead, F. C., Jr.; Varney, J. R.; Cote, C. E.

    1971-01-01

    Description of a feasibility experiment recently performed to test the use of a satellite system for telemetering environmental and physiological data from the winter den of a 'hibernating' black bear, Ursus americanus. The instrumentation procedure and evaluations of the equipment performance and sensory data obtained are discussed in detail.

  3. Bi-functional air electrodes for metal-air batteries. Final report, September 15, 1993--December 14, 1994

    SciTech Connect

    Swette, L.L.; Manoukian, M.; LaConti, A.B.

    1995-12-01

    The program was directed to the need for development of bifunctional air electrodes for Zn-Air batteries for the consumer market. The Zn-Air system, widely used as a primary cell for hearing-aid batteries and as a remote-site power source in industrial applications, has the advantage of high energy density, since it consumes oxygen from the ambient air utilizing a thin, efficient fuel-cell-type gas-diffusion electrode, and is comparatively low in cost. The disadvantages of the current technology are a relatively low rate capability, and the lack of simple reversibility. {open_quotes}Secondary{close_quotes} Zn-Air cells require a third electrode for oxygen evolution or mechanical replacement of the Zinc anodes; thus the development of a bifunctional air electrode (i.e., an electrode that can alternately consume and evolve oxygen) would be a significant advance in Zn-Air cell technology. Evaluations of two carbon-free non-noble metal perovskite-type catalyst systems, La{sub 1-x}CA{sub x}CoO{sub 3} as bifunctional catalysts for potential application in Zn-air batteries were carried out. The technical objectives were to develop higher-surface-area materials and to fabricate reversible electrodes by modifying the hydrophobic/hydrophilic balance of the catalyst-binder structures.

  4. Construction and evaluation of a novel bifunctional phenylalanine-formate dehydrogenase fusion protein for bienzyme system with cofactor regeneration.

    PubMed

    Jiang, Wei; Fang, Bai-Shan

    2016-05-01

    Phenylalanine dehydrogenase (PheDH) plays an important role in enzymatic synthesis of L-phenylalanine for aspartame (sweetener) and detection of phenylketonuria (PKU), suggesting that it is important to obtain a PheDH with excellent characteristics. Gene fusion of PheDH and formate dehydrogenase (FDH) was constructed to form bifunctional multi-enzymes for bioconversion of L-phenylalanine coupled with coenzyme regeneration. Comparing with the PheDH monomer from Microbacterium sp., the bifunctional PheDH-FDH showed noteworthy stability under weakly acidic and alkaline conditions (pH 6.5-9.0). The bifunctional enzyme can produce 153.9 mM L-phenylalanine with remarkable performance of enantiomers choice by enzymatic conversion with high molecular conversion rate (99.87 %) in catalyzing phenylpyruvic acid to L-phenylalanine being 1.50-fold higher than that of the separate expression system. The results indicated the potential application of the PheDH and PheDH-FDH with coenzyme regeneration for phenylpyruvic acid analysis and L-phenylalanine biosynthesis in medical diagnosis and pharmaceutical field. PMID:26819086

  5. Gold nanoparticle immobilization on ZnO nanorods via bi-functional monolayers: A facile method to tune interface properties

    NASA Astrophysics Data System (ADS)

    Jayaraman, Sundaramurthy; Suresh Kumar, P.; Mangalaraj, D.; Dharmarajan, Rajarathnam; Ramakrishna, Seeram; P Srinivasan, M.

    2015-11-01

    We demonstrated the functionalization of one dimensional (1-D) zinc oxide nanorods (ZnO NRs) using bi-functional organic molecules to create hybrid structures with surface functionalities and tuneable organic/inorganic interface. Bi-functional molecules with carboxylic acid, thiol and silane end groups and amine termination had been employed to functionalize the NRs by forming carboxylate, thiolate and hydroxylation bonds, respectively, with ZnO. The surface textures of NRs were preserved even after functionalization. The functionalized NRs were decorated with gold nanoparticles (AuNPs) and the hybrid structures exhibited a quenched blue shift ultraviolet emission which depended on the distance between the ZnO surface and the AuNPs. The NR functionalization with bi-functional molecules and decoration of NPs, and surface morphologies were analyzed using x-ray photoelectron spectroscopy, field emission scanning electron microscopy and transmission electron spectroscopy. These hybrid structures can play a vital role in tuning the interface properties and have potential applications in future photovoltaics, chemical sensors, biomarkers, and wavelength based biosensors.

  6. Molecular and biochemical characterization of bifunctional pyruvate decarboxylases and pyruvate ferredoxin oxidoreductases from Thermotoga maritima and Thermotoga hypogea.

    PubMed

    Eram, Mohammad S; Wong, Alton; Oduaran, Erica; Ma, Kesen

    2015-12-01

    Hyperthermophilic bacteria Thermotoga maritima and Thermotoga hypogea produce ethanol as a metabolic end product, which is resulted from acetaldehyde reduction catalysed by an alcohol dehydrogenase (ADH). However, the enzyme that is involved in the production of acetaldehyde from pyruvate is not well characterized. An oxygen sensitive and coenzyme A-dependent pyruvate decarboxylase (PDC) activity was found to be present in cell free extracts of T. maritima and T. hypogea. Both enzymes were purified and found to have pyruvate ferredoxin oxidoreductase (POR) activity, indicating their bifunctionality. Both PDC and POR activities from each of the purified enzymes were characterized in regards to their optimal assay conditions including pH dependency, oxygen sensitivity, thermal stability, temperature dependency and kinetic parameters. The close relatedness of the PORs that was shown by sequence analysis could be an indication of the presence of such bifunctionality in other hyperthermophilic bacteria. This is the first report of a bifunctional PDC/POR enzyme in hyperthermophilic bacteria. The PDC and the previously reported ADHs are most likely the key enzymes catalysing the production of ethanol from pyruvate in bacterial hyperthermophiles. PMID:26032540

  7. Himalayan black bear mauling: offense or defense?

    PubMed

    Thakur, Jagdeep Singh; Mohan, Chander; Sharma, Dev R

    2007-01-01

    The Asiatic Black Bear (Ursus thibetanus or Selenarctos thibetanus), also known as the Tibetan black bear, the Himalayan black bear, or the moon bear is a omnivorous mammal. This animal is declared threatened animal and rarely comes in human contact. Recent decrease in forest area has, however, increased the chances of bear-human interaction, hence causing injuries to humans. There is only one published report in English literature on Himalayan black bear mauling. We present 5 cases referred to our department over a period of 1 year. PMID:17606040

  8. TOOL ASSEMBLY WITH BI-DIRECTIONAL BEARING

    DOEpatents

    Longhurst, G.E.

    1961-07-11

    A two-direction motion bearing which is incorporated in a refueling nuclear fuel element trsnsfer tool assembly is described. A plurality of bi- directional bearing assembliesare fixed equi-distantly about the circumference of the transfer tool assembly to provide the tool assembly with a bearing surface- for both axial and rotational motion. Each bi-directional bearing assembly contains a plurality of circumferentially bulged rollers mounted in a unique arrangement which will provide a bearing surface for rotational movement of the tool assembly within a bore. The bi-direc tional bearing assembly itself is capable of rational motion and thus provides for longitudinal movement of the tool assembly.

  9. Alaskan brown bears, humans, and habituation

    USGS Publications Warehouse

    Smith, Thomas; Herrero, Stephen; DeBruyn, Terry D.

    2005-01-01

    We present a new paradigm for understanding habituation and the role it plays in brown bear (Ursus arctos) populations and interactions with humans in Alaska. We assert that 3 forms of habituation occur in Alaska: bear-to-bear, bear-to-human, and human-to-bear. We present data that supports our theory that bear density is an important factor influencing a bear’s overt reaction distance (ORD); that as bear density increases, overt reaction distance decreases, as does the likelihood of bear– human interactions. We maintain that the effects of bear-to-bear habituation are largely responsible for not only shaping bear aggregations but also for creating the relatively safe environment for bear viewing experienced at areas where there are high densities of brown bears. By promoting a better understanding of the forces that shape bear social interactions within populations and with humans that mingle with them, we can better manage human activities and minimize bear–human conflict.

  10. 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.

  11. Journal and Wave Bearing Impedance Calculation Software

    NASA Technical Reports Server (NTRS)

    Hanford, Amanda; Campbell, Robert

    2012-01-01

    The wave bearing software suite is a MALTA application that computes bearing properties for user-specified wave bearing conditions, as well as plain journal bearings. Wave bearings are fluid film journal bearings with multi-lobed wave patterns around the circumference of the bearing surface. In this software suite, the dynamic coefficients are outputted in a way for easy implementation in a finite element model used in rotor dynamics analysis. The software has a graphical user interface (GUI) for inputting bearing geometry parameters, and uses MATLAB s structure interface for ease of interpreting data. This innovation was developed to provide the stiffness and damping components of wave bearing impedances. The computational method for computing bearing coefficients was originally designed for plain journal bearings and tilting pad bearings. Modifications to include a wave bearing profile consisted of changing the film thickness profile given by an equation, and writing an algorithm to locate the integration limits for each fluid region. Careful consideration was needed to implement the correct integration limits while computing the dynamic coefficients, depending on the form of the input/output variables specified in the algorithm.

  12. Short-bearing approximation for full journal bearings

    NASA Technical Reports Server (NTRS)

    Ocvirk, F W

    1952-01-01

    A short-bearing approximation of pressure distribution in the oil film is presented which is an extension of the pressure-distribution function of Michell and Cardullo and includes end-leakage effects. Equations giving applied load, attitude angle, location and magnitude of peak film pressure, friction, and required oil flow rate as functions of the eccentricity ratio are also given. The capacity number, a basic non dimensional quantity resulting from this analysis is the product of the Sommerfeld number and the square of the length-diameter ratio. Curves determined by this analysis are compared with previously published experimental data and theoretical curves of Sommerfeld and Cameron and Wood. Conclusions reached indicate that this approximation is of practical value for analysis of short bearings.

  13. Mobile bearing and fixed bearing total knee arthroplasty

    PubMed Central

    Dolfin, Marco; Saccia, Francesco

    2016-01-01

    The mobile bearing (MB) concept in total knee arthroplasty (TKA) was developed as an alternative to fixed bearing (FB) implants in order to reduce wear and improve range of motion (ROM), especially focused on younger patients. Unfortunately, its theoretical advantages are still controversial. In this paper we exhibit a review of the more recent literature available comparing FB and MB designs in biomechanical and clinical aspects, including observational studies, clinical trials, national and international registries analyses, randomized controlled trials, meta-analyses and Cochrane reviews. Except for some minor aspects, none of the studies published so far has reported a significant improvement related to MBs regarding patient satisfaction, clinical, functional and radiological outcome or medium and long-term survivorship. Thus the presumed superiority of MBs over FBs appears largely inconsistent. The routine use of MB is not currently supported by adequate evidences; implant choice should be therefore made on the basis of other factors, including cost and surgeon experience. PMID:27162777

  14. 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.

  15. Report on the biological monitoring program for Bear Creek at the Oak Ridge Y-12 Plant, Oak Ridge, Tennessee, 1989-1994

    SciTech Connect

    Hinzman, R.L.; Beauchamp, J.J.; Cada, G.F.; Peterson, M.J.

    1996-04-01

    The Bear Creek Valley watershed drains the area surrounding several closed Oak Ridge Y-12 Plant waste disposal facilities. Past waste disposal practices in the Bear Creek Valley resulted in the contamination of Bear Creek and consequent ecological damage. Ecological monitoring by the Biological Monitoring and Abatement Program (BMAP) was initiated in the Bear Creek watershed in May 1984 and continues at present. Studies conducted during the first year provided a detailed characterization of the benthic invertebrate and fish communities in Bear Creek. The initial characterization was followed by a biological monitoring phase in which studies were conducted at reduced intensities.

  16. Research Initiatives

    Cancer.gov

    This page provides detailed information about currently funded RFA initiatives both led by DCCPS, and those led by other NIH Institutes and Centers (I/Cs) that include DCCPS as a partner. Each initiative includes a table of funded grants and a map that shows the location of funded institutions.

  17. Improved transducer for squeeze-film bearings

    NASA Technical Reports Server (NTRS)

    Hoogenbloom, L.

    1971-01-01

    Transducer amplifies vibrations produced by piezoelectric drivers, creating greater amplitudes than were possible with direct drive devices. Drivers isolated from bearing surfaces result in bearings with high axial load capacity and stiffness, thus, wear on ceramic cylinders is reduced.

  18. 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.

  19. A Preliminary Foil Gas Bearing Performance Map

    NASA Technical Reports Server (NTRS)

    DellaCorte, Christopher; Radil, Kevin C.; Bruckner, Robert J.; Howard, S. Adam

    2006-01-01

    Recent breakthrough improvements in foil gas bearing load capacity, high temperature tribological coatings and computer based modeling have enabled the development of increasingly larger and more advanced Oil-Free Turbomachinery systems. Successful integration of foil gas bearings into turbomachinery requires a step wise approach that includes conceptual design and feasibility studies, bearing testing, and rotor testing prior to full scale system level demonstrations. Unfortunately, the current level of understanding of foil gas bearings and especially their tribological behavior is often insufficient to avoid developmental problems thereby hampering commercialization of new applications. In this paper, a new approach loosely based upon accepted hydrodynamic theory, is developed which results in a "Foil Gas Bearing Performance Map" to guide the integration process. This performance map, which resembles a Stribeck curve for bearing friction, is useful in describing bearing operating regimes, performance safety margins, the effects of load on performance and limiting factors for foil gas bearings.

  20. Happy Birthday Smokey Bear from Joe Acaba

    NASA Video Gallery

    Expedition 32 Flight Engineer Joe Acaba wishes Smokey Bear a Happy Birthday. For 68 years Smokey Bear has been promoting fire safety and prevention through the message, “Only You Can Prevent Wild...

  1. Stable isotopes to detect food-conditioned bears and to evaluate human-bear management

    USGS Publications Warehouse

    Hopkins, John B., III; Koch, Paul L.; Schwartz, Charles C.; Ferguson, Jake M.; Greenleaf, Schuyler S.; Kalinowski, Steven T.

    2012-01-01

    We used genetic and stable isotope analysis of hair from free-ranging black bears (Ursus americanus) in Yosemite National Park, California, USA to: 1) identify bears that consume human food, 2) estimate the diets of these bears, and 3) evaluate the Yosemite human–bear management program. Specifically, we analyzed the isotopic composition of hair from bears known a priori to be food-conditioned or non-food-conditioned and used these data to predict whether bears with an unknown management status were food-conditioned (FC) or non-food-conditioned (NFC). We used a stable isotope mixing model to estimate the proportional contribution of natural foods (plants and animals) versus human food in the diets of FC bears. We then used results from both analyses to evaluate proactive (population-level) and reactive (individual-level) human–bear management, and discussed new metrics to evaluate the overall human–bear management program in Yosemite. Our results indicated that 19 out of 145 (13%) unknown bears sampled from 2005 to 2007 were food-conditioned. The proportion of human food in the diets of known FC bears likely declined from 2001–2003 to 2005–2007, suggesting proactive management was successful in reducing the amount of human food available to bears. In contrast, reactive management was not successful in changing the management status of known FC bears to NFC bears, or in reducing the contribution of human food to the diets of FC bears. Nine known FC bears were recaptured on 14 occasions from 2001 to 2007; all bears were classified as FC during subsequent recaptures, and human–bear management did not reduce the amount of human food in the diets of FC bears. Based on our results, we suggest Yosemite continue implementing proactive human–bear management, reevaluate reactive management, and consider removing problem bears (those involved in repeated bear incidents) from the population.

  2. Analysis of middle bearing failure in rotor jet engine using tip-timing and tip-clearance techniques

    NASA Astrophysics Data System (ADS)

    Rzadkowski, R.; Rokicki, E.; Piechowski, L.; Szczepanik, R.

    2016-08-01

    The reported problem is the failure of the middle bearing in an aircraft rotor engine. Tip-timing and tip-clearance and variance analyses are carried out on a compressor rotor blade in the seventh stage above the middle bearing. The experimental analyses concern both an aircraft engine with a middle bearing in good working order and an engine with a damaged middle bearing. A numerical analysis of seventh stage blade free vibration is conducted to explain the experimental results. This appears to be an effective method of predicting middle bearing failure. The results show that variance first increases in the initial stages of bearing failure, but then starts to decrease and stabilize, and then again decrease shortly before complete bearing failure.

  3. Mercury in polar bears from Alaska

    SciTech Connect

    Lentfer, J.W.; Galster, W.A.

    1987-04-01

    Alaskan polar bear (Ursus maritimus) muscle and liver samples collected in 1972 were analyzed for total mercury. Bears north of Alaska had more mercury than bears west of Alaska. The only difference between young and adult animals was in the northern area where adults had more mercury in liver tissue than young animals. Levels were probably not high enough to be a serious threat to bears.

  4. Research In Diagnosing Bearing Defects From Vibrations

    NASA Technical Reports Server (NTRS)

    Zoladz, T.; Earhart, E.; Fiorucci, T.

    1995-01-01

    Report describes research in bearing-defect signature analysis - use of vibration-signal analysis to diagnose defects in roller and ball bearings. Experiments performed on bearings in good condition and other bearings in which various parts scratched to provide known defects correlated with vibration signals. Experiments performed on highly instrumented motor-driven rotor assembly at speeds up to 10,050 r/min, using accelerometers, velocity probes, and proximity sensors mounted at various locations on assembly to measure vibrations.

  5. Human impacts on bear habitat use

    USGS Publications Warehouse

    Mattson, David J.

    1990-01-01

    : Human effects on bear habitat use are mediated through food biomass changes, bear tolerance of humans and their impacts, and human tolerance of bears. Large-scale changes in bear food biomass have been caused by conversion of wildlands and waterways to intensive human use, and by the introduction of exotic pathogens. Bears consume virtually all human foods that have been established in former wildlands, but bear use has been limited by access. Air pollution has also affected bear food biomass on a small scale and is likely to have major future impacts on bear habitat through climatic warming. Major changes in disturbance cycles and landscape mosaics wrought by humans have further altered temporal and spatial pulses of bear food production. These changes have brought short-term benefits in places, but have also added long-term stresses to most bear populations. Although bears tend to avoid humans, they will also use exotic and native foods in close proximity to humans. Subadult males and adult females are more often impelled to forage closer to humans because of their energetic predicament and because more secure sites are often preempted by adult males. Although male bears are typically responsible for most livestock predation, adult females and subadult males are more likely to be habituated to humans because they tend to forage closer to humans. Elimination of human-habituated bears predictably reduces effective carrying capacity and is more likely to be a factor in preserving bear populations where humans are present in moderate-to-high densities. If humans desire to preserve viable bear populations, they will either have to accept increased risk of injury associated with preserving habituated animals, or continue to crop habituated bears while at the same time preserving large tracts of wildlands free from significant human intrusion.

  6. Thin film superconductor magnetic bearings

    DOEpatents

    Weinberger, Bernard R.

    1995-12-26

    A superconductor magnetic bearing includes a shaft (10) that is subject to a load (L) and rotatable around an axis of rotation, a magnet (12) mounted to the shaft, and a stator (14) in proximity to the shaft. The stator (14) has a superconductor thin film assembly (16) positioned to interact with the magnet (12) to produce a levitation force on the shaft (10) that supports the load (L). The thin film assembly (16) includes at least two superconductor thin films (18) and at least one substrate (20). Each thin film (18) is positioned on a substrate (20) and all the thin films are positioned such that an applied magnetic field from the magnet (12) passes through all the thin films. A similar bearing in which the thin film assembly (16) is mounted on the shaft (10) and the magnet (12) is part of the stator (14) also can be constructed.

  7. Dynamics of air bearing sliders

    NASA Astrophysics Data System (ADS)

    Witelski, T. P.

    1998-03-01

    In this paper we present new results for the dynamics of a problem for the interaction of a compressible gas flow with a movable rigid surface. Compressible lubrication theory is applied to describe the dynamics of the vertical motion of air bearing sliders used in computer hard disk drives. In the limit of large bearing number we show this problem can be reduced to a nonlinear integrodifferential equation. Linear stability analysis and perturbation methods show that over the range of possible slider positions there is an infinite sequence of Hopf bifurcations yielding stable large amplitude periodic orbits. The dynamics of near-crash behavior and interaction with a moving disk surface are also addressed.

  8. Thin film superconductor magnetic bearings

    SciTech Connect

    Weinberger, B.R.

    1995-12-26

    A superconductor magnetic bearing includes a shaft that is subject to a load (L) and rotatable around an axis of rotation, a magnet mounted to the shaft, and a stator in proximity to the shaft. The stator has a superconductor thin film assembly positioned to interact with the magnet to produce a levitation force on the shaft that supports the load (L). The thin film assembly includes at least two superconductor thin films and at least one substrate. Each thin film is positioned on a substrate and all the thin films are positioned such that an applied magnetic field from the magnet passes through all the thin films. A similar bearing in which the thin film assembly is mounted on the shaft and the magnet is part of the stator also can be constructed. 8 figs.

  9. Air Bearing Lift Pad (ABLP)

    NASA Technical Reports Server (NTRS)

    Dane, Dan H.; Blaise, Herman T.

    1968-01-01

    Typical air bearings float on air films of only a few thousandths of an inch and so will only operate above very smooth, even surfaces. For the mechanical simulation of space, the small drag of the bladder type air pads is much more than can be coped with, and the practicality of large floor areas being machined for precision air bearings is nonexistent. To enable operation above surfaces that undulate slightly or feature cracks and discontinuities, an ABLP has been developed. It consists of a rigid pad beneath which an inflatable bladder is mounted. The bladder is inflated with air which then escapes through passages into a cavity in the center of the bladder to produce the lifting energy. As the air escapes about the perimeter of the bladder, a certain degree of balance and equilibrium is imparted to the pad as it is able to move a limited weight across slightly uneven surfaces.

  10. Foil bearing lubrication theory including compressibility effects

    NASA Technical Reports Server (NTRS)

    Gorla, Rama Subba Reddy; Catalano, Daniel A.

    1987-01-01

    An analysis is presented to determine the film thickness in a foil bearing. Using the Reynolds equation and including the compressibility effects of the gas, an equation was developed applicable to the film thickness in a foil bearing. The bearing was divided into three regions, namely, the entrance region, middle region and exit region. Solutions are obtained for the film thickness in each region.

  11. 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.

  12. 49 CFR 229.64 - Plain bearings.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 49 Transportation 4 2014-10-01 2014-10-01 false Plain bearings. 229.64 Section 229.64 Transportation Other Regulations Relating to Transportation (Continued) FEDERAL RAILROAD ADMINISTRATION....64 Plain bearings. A plain bearing box shall contain visible free oil and may not be cracked to...

  13. 49 CFR 229.64 - Plain bearings.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 49 Transportation 4 2011-10-01 2011-10-01 false Plain bearings. 229.64 Section 229.64 Transportation Other Regulations Relating to Transportation (Continued) FEDERAL RAILROAD ADMINISTRATION....64 Plain bearings. A plain bearing box shall contain visible free oil and may not be cracked to...

  14. 14 CFR 25.623 - Bearing factors.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 14 Aeronautics and Space 1 2011-01-01 2011-01-01 false Bearing factors. 25.623 Section 25.623... STANDARDS: TRANSPORT CATEGORY AIRPLANES Design and Construction General § 25.623 Bearing factors. (a) Except... subject to pounding or vibration, must have a bearing factor large enough to provide for the effects...

  15. 14 CFR 25.623 - Bearing factors.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Bearing factors. 25.623 Section 25.623... STANDARDS: TRANSPORT CATEGORY AIRPLANES Design and Construction General § 25.623 Bearing factors. (a) Except... subject to pounding or vibration, must have a bearing factor large enough to provide for the effects...

  16. 14 CFR 29.623 - Bearing factors.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 14 Aeronautics and Space 1 2013-01-01 2013-01-01 false Bearing factors. 29.623 Section 29.623... STANDARDS: TRANSPORT CATEGORY ROTORCRAFT Design and Construction General § 29.623 Bearing factors. (a... subject to pounding or vibration, must have a bearing factor large enough to provide for the effects...

  17. 14 CFR 29.623 - Bearing factors.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 14 Aeronautics and Space 1 2014-01-01 2014-01-01 false Bearing factors. 29.623 Section 29.623... STANDARDS: TRANSPORT CATEGORY ROTORCRAFT Design and Construction General § 29.623 Bearing factors. (a... subject to pounding or vibration, must have a bearing factor large enough to provide for the effects...

  18. 14 CFR 27.623 - Bearing factors.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 14 Aeronautics and Space 1 2014-01-01 2014-01-01 false Bearing factors. 27.623 Section 27.623... STANDARDS: NORMAL CATEGORY ROTORCRAFT Design and Construction General § 27.623 Bearing factors. (a) Except... subject to pounding or vibration, must have a bearing factor large enough to provide for the effects...

  19. 49 CFR 229.64 - Plain bearings.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 49 Transportation 4 2012-10-01 2012-10-01 false Plain bearings. 229.64 Section 229.64 Transportation Other Regulations Relating to Transportation (Continued) FEDERAL RAILROAD ADMINISTRATION....64 Plain bearings. A plain bearing box shall contain visible free oil and may not be cracked to...

  20. 14 CFR 27.623 - Bearing factors.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 14 Aeronautics and Space 1 2011-01-01 2011-01-01 false Bearing factors. 27.623 Section 27.623... STANDARDS: NORMAL CATEGORY ROTORCRAFT Design and Construction General § 27.623 Bearing factors. (a) Except... subject to pounding or vibration, must have a bearing factor large enough to provide for the effects...