These are representative sample records from Science.gov related to your search topic.
For comprehensive and current results, perform a real-time search at Science.gov.
1

Concurrent initialization for Bearing-Only SLAM.  

PubMed

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

Munguía, Rodrigo; Grau, Antoni

2010-01-01

2

DISTURBANCE AND INITIAL STATE UNCERTAINTY ATTENUATION CONTROL FOR MAGNETIC BEARINGS  

E-print Network

to design such controller for MIMO complex systems. A mixed Disturbance and an Initial-state uncertainty, active magnetic bearings allow contract-free suspension of rotors and they are used for various industrial purposes. We derive a mathemati- cal model of the magnetic bearing which has complicated rotor

3

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

Federal Register 2010, 2011, 2012, 2013, 2014

...Ball Bearings and Parts Thereof From Germany: Initiation of Antidumping Duty Changed-Circumstances...on ball bearings and parts thereof from Germany with respect to myonic GmbH. DATES...plain bearings and parts thereof from Germany on May 15, 1989. See Antidumping...

2010-01-21

4

Trimetallic magnesium complexes bearing amine-bis(benzotriazole phenolate) derivatives as bifunctional catalysts for ring-opening polymerization and CO2/epoxide coupling.  

PubMed

New trimetallic magnesium complexes were synthesized for bifunctional catalysis. Complex catalysed ?-caprolactone polymerizations in not only a 'living' manner but also in an 'immortal' fashion. Additionally, tri-Mg was active for the coupling of CO(2) with cyclohexene oxide (CHO) on addition of n-Bu(4)NBr co-catalysts to give cis-cyclohexene carbonate under mild conditions. PMID:22911045

Li, Chen-Yu; Wu, Chen-Ruei; Liu, Yi-Chang; Ko, Bao-Tsan

2012-10-01

5

Bears  

NSDL National Science Digital Library

What are the characteristics of grizzly/brown bears and black bears? As you view the websites, please use this chart to record what you are learning about grizzly bears and black bears. For each bear, you should list 5 characteristics. Grizzly Bear and Black Bear Chart We will first begin by learning about black bears. Please go to these websites to learn some important facts about black bears. Black Bears Facts and Image Black Bear Facts for Kids Now that you have learned ...

Miss Bledsoe

2011-04-07

6

Sequential Bearings-Only-Tracking Initiation with Particle Filtering Method  

PubMed Central

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

Hao, Chengpeng

2013-01-01

7

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

E-print Network

The Sensitivity of Convective Initiation to the Lapse Rate of the Active Cloud-Bearing Layer ADAM L Departments of Agronomy and Earth and Atmospheric Sciences, Purdue University, West Lafayette, Indiana (DCI) to the lapse rate of the active cloud-bearing layer [ACBL; the atmo- spheric layer above

Niyogi, Dev

8

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

Federal Register 2010, 2011, 2012, 2013, 2014

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

2013-01-15

9

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

Federal Register 2010, 2011, 2012, 2013, 2014

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

2012-08-09

10

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

Federal Register 2010, 2011, 2012, 2013, 2014

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

2013-08-19

11

Bears, Bears, Bears!  

NSDL National Science Digital Library

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

Ms.Beason

2011-04-16

12

Surface-initiated spalling fatigue in M-50 and M-50 NiL bearings  

SciTech Connect

The initiation and development of spalling fatigue in M-50 and M-50 NiL thrust bearings running under partial EHD lubrication conditions have been studied. The inner and outer rings of the M-50 NiL bearings were plated with thin hard dense chromium (TDC), and the bearing was assembled with M-50 balls. A spectrum of initial surface flaws was introduced during a prescribed run in a separate test machine in which the oil had been contaminated with 2.5 ppm of 20-micron alumina. The initial flaws propagated by a micropeeling mechanism, and these developed into macroscopic spalls when the peeled region reached a critical size. The L10 life of the surface-damaged M-50 bearings was 87 hours, compared to a calculated AFBMA L10 of 24 hours. The M-50 NiL, TDC rings had an L10 of 480 hours, under the same test conditions. The enhancement of the life of M-50 NiL, TDC over M-50 by a factor of about six is ascribed in part to the presence of residaul compressive stresses in the subsurface regions of the M-50 NiL rings. 7 refs.

Averbach, B.L.; Van pelt, S.G.; Pearson, P.K.; Bamberger, E.N. (MIT, Cambridge, MA (United States) Torrington Co., Fafnir Div., Torrington, CT (United States) General Electric Co., Aircraft Engine Group, Cincinnati, OH (United States))

1991-10-01

13

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

Microsoft Academic Search

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

S. I. Kwun; R. A. Fournelle

1982-01-01

14

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

Federal Register 2010, 2011, 2012, 2013, 2014

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

2012-11-08

15

Initiation and propagation of coagulation from tissue factor-bearing cell monolayers to plasma: initiator cells do not regulate spatial growth rate  

Microsoft Academic Search

Summary. Exposure of tissue factor (TF)-bearing cells to blood is the initial event in coagulation and intravascular thrombus formation. However, the mechanisms which deter- mine thrombus growth remain poorly understood. To explore whether the procoagulant activity of vessel wall-bound cells regulates thrombus expansion, we studied in vitro spatial clot growth initiated by cultured human cells of different types in contact

M. V. OVANESOV; N. M. ANANYEVA; M. A. PANTELEEV; F. I. ATAULLAKHANOV; E. L. SAENKO

2005-01-01

16

Initial in vivo evaluation of the newly developed axial flow turbo pump with hydrodynamic bearings.  

PubMed

An implantable, compact rotary blood pump has been newly developed using an axial flow turbo pump with hydrodynamic bearings. The rotating impeller, which is hydrodynamically levitated with the assistance of repulsive magnetic force, has no contact with the inner surface of the pump. To evaluate the hemodynamic performance and biocompatibility, the pump was installed into four calves for up to 90 days. The pump was installed in the left heart bypass fashion, and placed paracorporeally in the first two calves and in the thoracic cavity in the other two calves. All calves received anticoagulation and antiaggregation therapy during the study. Aortic pressure, heart rate and pump-operating parameters were continuously measured. Hematologic and biochemical tests to evaluate anemia, hepato-renal function and the extent of hemolysis were performed on schedule. Each calf was killed at the termination of the experiments, and pathological analysis for the biocompatibility of the pump system was performed, including the thrombi in the device, emboli in the systemic organs and signs of infection. The pump stably produced a flow of 5 l/min. Each calf was supported for 78, 50, 90 and 90 days, respectively, with no incidence of hemorrhage, organ failure or significant hemolysis. No thrombus formation or mechanical wearing was observed inside the pump. There was no evidence of heat injury around the pump. Device-related infections were observed, but the severity of infection was mild in the implant case compared to the paracorporeal case. The pump demonstrated acceptable hemodynamic performance and biocompatibility in the initial in vivo testing. PMID:21207088

Tanaka, Hideyuki; Tsukiya, Tomonori; Tatsumi, Eisuke; Mizuno, Toshihide; Hidaka, Tatsuya; Okubo, Takeshi; Osada, Toshiyuki; Miyamoto, Shinji; Taenaka, Yoshiyuki

2011-03-01

17

Living Carbocationic Polymerization of Isobutylene with Blocked Bifunctional Initiators in the Presence of Di-tert-butylpyridine as a Proton Trap  

Microsoft Academic Search

The polymerization of isobutylene (IB) has been studied using 5-tert-butyl-1,3-dicumyl-chloride, 5-tert-butyl-1,3-dicumyl-methyl ether, and 5-tert-butyl-1,3-dicumyl-acetate initiators in the absence and presence of 2,6-di-tert-butylpyridine (DTBP) as a proton trap. It is demonstrated that living polymerization can be achieved in the IB\\/initiator\\/TiCl4\\/methylchloride-n-hexane (40:60 v:v)\\/DTBP\\/-80°C system, and that polymers with close to a Poisson molecular weight distribution can be obtained in the presence of

Miklos Gyor; Hsien-Chang Wang; Rudolf Faust

1992-01-01

18

VARIATIONAL CONVERGENCE OF BIFUNCTIONS: MOTIVATING ...  

E-print Network

Jan 28, 2011 ... analyze convergence notion(s) for bifunctions that in turn will guarantee the ... equilibrium for non-cooperative games and Walras economic ...... the beginning of this section and (u? ? D?) ? u yields u ? D by Proposition 5.1.

2011-01-28

19

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

PubMed

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

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

2004-07-01

20

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

PubMed Central

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

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

2014-01-01

21

Poly(ether-ether-ketone) orthopedic bearing surface modified by self-initiated surface grafting of poly(2-methacryloyloxyethyl phosphorylcholine).  

PubMed

We investigated the production of free radicals on a poly(ether-ether-ketone) (PEEK) substrate under ultraviolet (UV) irradiation. The amount of the ketyl radicals produced from the benzophenone (BP) units in the PEEK molecular structure initially increased rapidly and then became almost constant. Our observations revealed that the BP units in PEEK acted as photoinitiators, and that it was possible to use them to control the graft polymerization of poly(2-methacryloyloxyethyl phosphorylcholine) (PMPC). This "self-initiated surface graft polymerization" method is very convenient in the absence of external photoinitiator. We also investigated the effects of the monomer concentration and UV irradiation time on the extent of the grafted PMPC layer. Furthermore, as an application to improving the durability of artificial hips, we demonstrated the nanometer-scale photoinduced grafting of PMPC onto PEEK and carbon fiber-reinforced PEEK (CFR-PEEK) orthopedic bearing surfaces and interfaces. A variety of test revealed significant improvements in the water wettability, frictional properties, and wear resistance of the surfaces and interfaces. PMID:23891520

Kyomoto, Masayuki; Moro, Toru; Yamane, Shihori; Hashimoto, Masami; Takatori, Yoshio; Ishihara, Kazuhiko

2013-10-01

22

Tailored bifunctional polymer for plutonium monitoring.  

PubMed

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

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

2014-07-01

23

A bifunctional nanocarrier based on amphiphilic hyperbranched polyglycerol derivatives  

E-print Network

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

Peters, Achim

24

Biochemical and Structural Characterization of the Arabidopsis Bifunctional Enzyme Dethiobiotin  

E-print Network

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

Paris-Sud XI, Université de

25

Polar Bears  

NSDL National Science Digital Library

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

Mr. Thomas

2010-09-27

26

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

NASA Astrophysics Data System (ADS)

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

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

2014-01-01

27

Bearing system  

DOEpatents

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.

Kapich, Davorin D. (Carlsbad, CA)

1987-01-01

28

Diversity-oriented synthesis leads to an effective class of bifunctional linchpins uniting anion relay chemistry (ARC) with benzyne reactivity.  

PubMed

In conjunction with the construction of a diversity-oriented synthesis library of 10-membered ring "natural product-like" macrolides, the design, synthesis, and validation of a unique class of bifunctional linchpins, uniting benzyne reactivity initiated by type II anion relay chemistry (ARC) has been achieved, permitting access to diverse [2+2], [3+2], and [4+2] cycloadducts. PMID:21245309

Smith, Amos B; Kim, Won-Suk

2011-04-26

29

Polar Bear Polar Bear  

NSDL National Science Digital Library

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

Kelly Burgess

2012-09-11

30

Development of Benzophenone-Alkyne Bifunctional Sigma Receptor Ligands  

PubMed Central

Sigma (?) receptors represent unique non-opioid binding sites that are associated with a broad range of disease states. Sigma-2 receptors provide a promising target for diagnostic imaging and pharmacological interventions to curb tumor progression. Most recently, the progesterone receptor (PGRMC1, 25 kDa) has been identified to contain ?2 receptor-like binding properties, highlighting the need to understand the biological function of an 18-kDa protein that exhibits ?2-like photoaffinity labeling (herein denoted as ?2-18k) but the amino acid sequence of which is not known. In order to provide novel tools for the study of the ?2-18k protein, we have developed bifunctional sigma receptor ligands that bear a benzophenone photo-crosslinking moiety and an alkyne group, to which an azide-containing biotin affinity tag can be covalently attached via click chemistry following photo-crosslink. While several compounds showed favorable ?2 binding properties, compound 22 exhibited the highest affinity (2 nM) and the greatest potency in blocking photolabeling of the ?2-18k by a radioactive photoaffinity ligand. Thus, these benzophenone-alkyne sigma receptor ligands may be amenable for studying the ?2-18k protein via chemical biology approaches. To our knowledge, these compounds represent the first reported benzophenone-containing clickable sigma receptor ligands, which may potentially serve broad applications by “plugging” in various tags. PMID:23001760

Guo, Lian-Wang; Hajipour, Abdol R.; Karaoglu, Kerim; Mavlyutov, Timur A.; Ruoho, Arnold E.

2012-01-01

31

Bear Scratch  

USGS Multimedia Gallery

When looking for a place to set up a trapping location, scientists look for existing bear sign such as scratches on trees and bear scat. Sometimes traps are set in areas that have no obvious bear sign to determine if indeed bears are present....

32

Bifunctional nanoarrays for probing the immune response at the single-molecule level  

PubMed Central

Bifunctional nanoarrays were created to simulate the immunological synapse and probe the T-cell immune response at the single-molecule level. Sub-5?nm AuPd nanodot arrays were fabricated using both e-beam and nanoimprint lithography. The nanoarrays were then functionalized by two costimulatory molecules: antibody UCHT1 Fab, which binds to the T-cell receptor (TCR) and activates the immune response, bound to metallic nanodots; and intercellular adhesion molecule-1, which enhances cell adhesion, on the surrounding area. Initial T-cell experiments show successful attachment and activation on the bifunctional nanoarrays. This nanoscale platform for single-molecule control of TCR in living T-cells provides a new approach to explore how its geometric arrangement affects T-cell activation and behavior, with potential applications in immunotherapy. This platform also serves as a general model for single-molecule nanoarrays where more than one molecular species is required. PMID:24353927

Cai, Haogang; Depoil, David; Palma, Matteo; Sheetz, Michael P.; Dustin, Michael L.; Wind, Shalom J.

2013-01-01

33

Tethering metal ions to photocatalyst particulate surfaces by bifunctional molecular linkers for efficient hydrogen evolution.  

PubMed

A simple and versatile method for the preparation of photocatalyst particulates modified with effective cocatalysts is presented; the method involves the sequential soaking of photocatalyst particulates in solutions containing bifunctional organic linkers and metal ions. The modification of the particulate surfaces is a universal and reproducible method because the molecular linkers utilize strong covalent bonds, which in turn result in modified monolayer with a small but controlled quantity of metals. The photocatalysis results indicated that the CdS with likely photochemically reduced Pd and Ni, which were initially immobilized via ethanedithiol (EDT) as a linker, were highly efficient for photocatalytic hydrogen evolution from Na2S-Na2SO3-containing aqueous solutions. The method developed in this study opens a new synthesis route for the preparation of effective photocatalysts with various combinations of bifunctional linkers, metals, and photocatalyst particulate materials. PMID:25138439

Yu, Weili; Isimjan, Tayirjan; Del Gobbo, Silvano; Anjum, Dalaver H; Abdel-Azeim, Safwat; Cavallo, Luigi; Garcia-Esparza, Angel T; Domen, Kazunari; Xu, Wei; Takanabe, Kazuhiro

2014-09-01

34

Bifunctional redox tagging of carbon nanoparticles  

NASA Astrophysics Data System (ADS)

Despite extensive work on the controlled surface modification of carbon with redox moieties, to date almost all available methodologies involve complex chemistry and are prone to the formation of polymerized multi-layer surface structures. Herein, the facile bifunctional redox tagging of carbon nanoparticles (diameter 27 nm) and its characterization is undertaken using the industrial dye Reactive Blue 2. The modification route is demonstrated to be via exceptionally strong physisorption. The modified carbon is found to exhibit both well-defined oxidative and reductive voltammetric redox features which are quantitatively interpreted. The method provides a generic approach to monolayer modifications of carbon and carbon nanoparticle surfaces.

Poon, Jeffrey; Batchelor-McAuley, Christopher; Tschulik, Kristina; Palgrave, Robert G.; Compton, Richard G.

2015-01-01

35

Polar Bear  

NSDL National Science Digital Library

This site from the World Wildlife Fund (WWF) International provides general information about polar bears as well as data on the movements of two radio-collared bears, along with the ice status, through a series of online maps.

2007-01-01

36

A new look at Pennsylvanian coal-bearing strata of the East Midlands, UK: initial data from the Smalley open pit mine  

NASA Astrophysics Data System (ADS)

Outcrops of Pennsylvanian (Duckmantian) age coal-bearing strata in the East Midlands of England are rare and have become rarer as more of the surface environment has been developed. Much of the stratigraphic correlation and paleoenvironmental interpretation of these strata have thus been based on subsurface data from deep mine workings and coal exploration boreholes. However, in 2009, coal mining commenced at an open pit mine near Smalley, east Derbyshire in the UK East Midlands. The mine provides a unique opportunity to carry out examination of a large-scale outcrop of Pennsylvanian coal-bearing strata in order to undertake detailed palaeoenvironmental reconstructions. The coals that will be exposed during working belong to the Waterloo group of seams of Duckmantian age. Initial examination of the workings has been concentrated on two successive intervals: from the basal Third Waterloo Seam to the Bottom Second Waterloo seam, and the from above the Bottom Second Waterloo seam to the Top Second Waterloo seam. The two inter-seam intervals are approximately 10-12 meters thick. Examination of the coal seams and inter-seam intervals will continue as new faces are exposed, supplemented by exploration drilling data. Initial field observations on the first sections exposed suggest that the two inter-seam intervals represent the infill of lakes formed on a fluvio-lacustrine plain, with negligible marine influence. The strata immediately above the Third Waterloo Seam consist of dark grey fissile shaly mudrocks overlain by an upward coarsening sequence of pale grey siltstones with sandy laminae and current ripples indicating unidirectional tractional flows. These pass upwards into rippled fine sandstones, cut by shallow channels towards the top. The overall inter-seam sequence is interpreted as the deposits of a lacustrine delta system that infilled a shallow lake that was initially anoxic. Once the lake had been infilled, a peat mire was able to form, now represented by the Bottom Second Waterloo Seam. The interval between the Bottom and Top Waterloo Seams contains an upward-coarsening sequence of laminated siltstones, overlain by a series of sharp-based rippled sandstones, each up to about 60 cm thick. The sharp based sandstones are interpreted as being crevasse splay deposits, which would have been fed by a nearby fluvial channel, which has not yet been located. As additional exposures are created during the lifetime of the mine, the temporal, spatial and environmental relationships of the coals and inter-seam strata will be investigated further by recording stratigraphic sections and directional data and producing photo panels. This should enable detailed paleoenvironmental reconstructions for each of the intervals investigated, which will be considered in the light of recent research on analogous ancient and recent environments. Data from adjacent former mines and coal exploration boreholes containing lateral continuations of the intervals examined will then allow the Smalley mine geology to be placed within the regional context of the East Midlands Coalfield, and enable us to consider broad scale paleoenvironmental variation across the area. It is anticipated that by enhancing our understanding of inter-seam deposits, prediction of geological conditions ahead of mining will be improved.

Sian Davies-Vollum, K.; Guion, Paul; Satterfield, Dorothy; Suthren, Roger

2010-05-01

37

Bifunctional Ligands Allow Deliberate Extrinsic Reprogramming of the Glucocorticoid Receptor  

PubMed Central

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-?B. 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

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

2014-01-01

38

Bearing fatigue investigation 3  

NASA Technical Reports Server (NTRS)

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.

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

1982-01-01

39

Particle migration through sealed bearings  

SciTech Connect

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.

Sundvold, P.D.

1993-08-01

40

Synthesis and Preclinical Evaluation of Bifunctional Ligands for Improved Chelation Chemistry of 90Y and 177Lu for Targeted Radioimmunotherapy  

PubMed Central

We report a practical and high yield synthesis of a bimodal bifunctional ligand 3p-C-NETA-NCS containing the isothiocyanate group for conjugation to a tumor targeting antibody. 3p-C-NETA-NCS was conjugated to a tumor-targeting antibody, trastuzumab, and the corresponding 3p-C-NETA-trastuzumab conjugate was evaluated and compared to trastuzumab conjugates of the known bifunctional ligands C-DOTA, C-DTPA, C-NOTA, and 3p-C-DEPA for radiolabeling kinetics with 90Y and 177Lu. 3p-C-NETA-trastuzumab conjugate exhibited extremely rapid complexation kinetics with 90Y and 177Lu. 90Y-3p-C-NETA-trastuzumab and 177Lu-3p-C-NETA-trastuzumab conjugates were stable in human serum for 2 weeks. A pilot biodistribution study was conducted to evaluate in vivo stability and tumor targeting of 177Lu-radiolabeled trastuzumab conjugate using nude mice bearing ZR-75-1 human breast cancer. 177Lu-3p-C-NETA-trastuzumab conjugate displayed low radioactivity level at blood (1.6%), low organ uptake (<2.2%), and high tumor-to-blood ratio (6.4) at 120 h. 3p-C-NETA possesses favorable in vitro and in vivo profiles and is an excellent bifunctional chelator that can be used for targeted RIT applications using 90Y and 177Lu and has potential to replace DOTA and DTPA analogues in current clinical use. PMID:22881720

Kang, Chi Soo; Sun, Xiang; Jia, Fang; Song, Hyun A; Chen, Yunwei; Lewis, Michael; Chong, Hyun-Soon

2012-01-01

41

New bifunctional metalloproteinase inhibitors: an integrated approach towards biological improvements and cancer therapy.  

PubMed

The key role of some matrix metalloproteinases (MMPs) on several pathological processes, including carcinogenesis and tumor growth, makes the development of MMP inhibitors (MMPIs) an attractive approach for cancer therapy. We present herein an integrated approach for the development of a new series of inhibitors of MMP2 and MMP14, two enzymes over-expressed by human ovarian cancer. As a first step, a new series of single model compounds bearing different zinc-binding groups (ZBGs), such as carboxylic, hydroxamic acid, hydrazide and sulfonylhydrazide groups, were studied and revealed reasonably good capacity for the Zn(II) chelation in solution and for the MMP inhibition. Aimed at further reinforcing the biological activity of these MMPIs as anti-cancer agents, a selection of those models was extra-functionalized with benzothiazole (BTA), a group with recognized antitumor activity. Analysis of the results obtained for these bifunctional compounds, in particular the inhibitory activity against MMP2 and MMP14 as well as the anti-proliferative activity on the A2780 ovarian cancer cell line, allowed to understand the activity dependence on the type of ZBG, as well as the relevance of the BTA moiety. Overall, the evidenced BTA-associated activity improvements on enzyme inhibition and cell antiproliferactivity, combined with the hydrolytic stability revealed by the hydrazide group, suggest that these new bifunctional BTA-hydrazide derivatives should be taken in consideration for the development of new generations of MMPIs with anti-cancer activity. PMID:23597851

Marques, Sérgio M; Abate, Claudia C; Chaves, Sílvia; Marques, Fernanda; Santos, Isabel; Nuti, Elisa; Rossello, Armando; Santos, M Amélia

2013-10-01

42

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

PubMed Central

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

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

43

Polar Bear  

USGS Publications Warehouse

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.

Amstrup, S.D.; DeMaster

1988-01-01

44

Magnetic Bearing  

NASA Technical Reports Server (NTRS)

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.

1996-01-01

45

Polar Bear  

NSDL National Science Digital Library

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

2009-01-01

46

Strategies for the preparation of bifunctional gadolinium(III) chelators  

PubMed Central

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

Frullano, Luca; Caravan, Peter

2012-01-01

47

Bobbie Bear  

NSDL National Science Digital Library

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

Illuminations National Council of Teachers of Mathematics

2009-03-06

48

Foil bearings  

NASA Technical Reports Server (NTRS)

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.

Elrod, David A.

1993-01-01

49

Bifunctional Homodimeric Triokinase/FMN Cyclase  

PubMed Central

Mammalian triokinase, which phosphorylates exogenous dihydroxyacetone and fructose-derived glyceraldehyde, is neither molecularly identified nor firmly associated to an encoding gene. Human FMN cyclase, which splits FAD and other ribonucleoside diphosphate-X compounds to ribonucleoside monophosphate and cyclic X-phosphodiester, is identical to a DAK-encoded dihydroxyacetone kinase. This bifunctional protein was identified as triokinase. It was modeled as a homodimer of two-domain (K and L) subunits. Active centers lie between K1 and L2 or K2 and L1: dihydroxyacetone binds K and ATP binds L in different subunits too distant (?14 ?) for phosphoryl transfer. FAD docked to the ATP site with ribityl 4?-OH in a possible near-attack conformation for cyclase activity. Reciprocal inhibition between kinase and cyclase reactants confirmed substrate site locations. The differential roles of protein domains were supported by their individual expression: K was inactive, and L displayed cyclase but not kinase activity. The importance of domain mobility for the kinase activity of dimeric triokinase was highlighted by molecular dynamics simulations: ATP approached dihydroxyacetone at distances below 5 ? in near-attack conformation. Based upon structure, docking, and molecular dynamics simulations, relevant residues were mutated to alanine, and kcat and Km were assayed whenever kinase and/or cyclase activity was conserved. The results supported the roles of Thr112 (hydrogen bonding of ATP adenine to K in the closed active center), His221 (covalent anchoring of dihydroxyacetone to K), Asp401 and Asp403 (metal coordination to L), and Asp556 (hydrogen bonding of ATP or FAD ribose to L domain). Interestingly, the His221 point mutant acted specifically as a cyclase without kinase activity. PMID:24569995

Rodrigues, Joaquim Rui; Couto, Ana; Cabezas, Alicia; Pinto, Rosa María; Ribeiro, João Meireles; Canales, José; Costas, María Jesús; Cameselle, José Carlos

2014-01-01

50

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

PubMed

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

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

51

Cave Bear  

NSDL National Science Digital Library

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

American Association for the Advancement of Science (; )

2005-08-15

52

Bifunctional Asymmetric Catalysis: Cooperative Lewis Acid/Base Systems  

E-print Network

Bifunctional Asymmetric Catalysis: Cooperative Lewis Acid/Base Systems DANIEL H. PAULL, CIBY J a distinct Lewis acid to coordinate and acti- vate the electrophile, which in turn increases the reaction of the difficulty is the large potential for quenching reactions; for instance, the Lewis acid may react

Lectka, Thomas

53

Bifunctional Asymmetric Catalysis: A Tandem Nucleophile/Lewis Acid  

E-print Network

not function as intended. One of the most common reasons is the interference of a self-quenching reaction, a bifunctional system for the acceleration of the Baylis-Hillman reaction was reported wherein the authors combined a metal salt with a catalytic nucleophile, such as dabco.2 Remarkably, the nucleophile and Lewis

Lectka, Thomas

54

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

NASA Astrophysics Data System (ADS)

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

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

2013-06-01

55

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

USGS Publications Warehouse

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.

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

1969-01-01

56

Bearing monitoring  

Microsoft Academic Search

At Ford Motor Company, thrust bearing in drill motors is often damaged by metal chips. Since the vibration frequency is several Hz only, it is very difficult to use accelerometers to pick up the vibration signals. Under the support of Ford and NASA, we propose to use a piezo film as a sensor to pick up the slow vibrations of

Roger Xu; Mark W. Stevenson; Chiman Kwan; Leonard S. Haynes

2001-01-01

57

Bear Bones  

NSDL National Science Digital Library

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

Science Update

2004-03-08

58

Tooling Converts Stock Bearings To Custom Bearings  

NASA Technical Reports Server (NTRS)

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.

Fleenor, E. N., Jr.

1983-01-01

59

Isotopically-coded short-range hetero-bifunctional photo-reactive crosslinkers for studying protein structure.  

PubMed

The resolution and the fidelity of a protein structural model, constructed using crosslinking data, is dependent on the crosslinking distance constraints. Most of the popular amine-reactive NHS-ester crosslinkers are limited in their capacity to provide short distance constraints because of the rarity of lysine residues occurring in close proximity in the protein structure. To solve this problem, hetero-bifunctional crosslinkers containing both a photo-reactive functional group and an NHS-ester group can be used to enable non-specific crosslinking within the proximity of these lysine residues. Here we develop three such isotopically-coded hetero-bifunctional photo-reactive crosslinkers, bearing azido, diazirine or benzophenone photo-reactive groups (azido-benzoic-acid-succinimide (ABAS)-(12)C6/(13)C6, succinimidyl-diazirine (SDA)-(12)C5/(13)C5, and carboxy-benzophenone-succinimide (CBS)-(12)C6/(13)C6, respectively). These crosslinkers were validated using several model proteins/peptides and were then applied to study the structure of the native ?-synuclein protein. In that case the ABAS crosslinker proved to be the most suitable, with 10 crosslinks being found in the native ?-synuclein structure. PMID:25192908

Brodie, Nicholas I; Makepeace, Karl A T; Petrotchenko, Evgeniy V; Borchers, Christoph H

2014-09-01

60

Advances In Magnetic Bearings  

NASA Technical Reports Server (NTRS)

NASA technical memorandum reviews state of technology of magnetic bearings, focusing mainly on attractive bearings rather than repulsive, eddy-current, or Lorentz bearings. Attractive bearings offer greater load capacities and preferred for aerospace machinery.

Fleming, David P.

1994-01-01

61

Preparation of a Versatile Bifunctional Zeolite for Targeted Imaging Applications  

PubMed Central

Bifunctional zeolite Y was prepared for use in targeted in vivo molecular imaging applications. The strategy involved functionalization of the external surface of zeolite Y with chloropropyltriethoxysilane followed by reaction with sodium azide to form azide-functionalized NaY, which is amenable to copper(1) catalyzed click chemistry. In this study, a model alkyne (4-pentyn-1-ol) was attached to the azide-terminated surface via click chemistry to demonstrate feasibility for attachment of molecular targeting vectors (e.g., peptides, aptamers) to the zeolite surface. The modified particle efficiently incorporates the imaging radioisotope gallium-68 (68Ga) into the pores of the azide-functionalized NaY zeolite to form a stable bifunctional molecular targeting vector. The result is a versatile “clickable” zeolite platform that can be tailored for future in vivo molecular targeting and imaging modalities. PMID:21306141

Ndiege, Nicholas; Raidoo, Renugan; Schultz, Michael K.; Larsen, Sarah

2011-01-01

62

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

PubMed

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

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

2014-01-01

63

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

NASA Astrophysics Data System (ADS)

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.

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

2014-10-01

64

Low VOC bifunctional photoinitiator based on ?-hydroxyalkylphenone structure  

Microsoft Academic Search

A novel bifunctional photoinitiator (PI), bis[4-(2-hydroxy-isopropionyl)]ether (BHPE), was synthesized and characterized. Photophysics investigation showed that the absorption maximum of BHPE was at 281nm, red shifted about 40nm compared to the commercial photoinitiators 2-hydroxy-2-methyl-1-phenyl-propan-1-one (HMPP) and 1-hydroxycyclohexyl phenyl ketone (HCPK), dropping into the UVB region, and the fluorescence lifetime and fluorescence quantum yields of BHPE were found to be 14.2ns and

Guodong Ye; Zhuofeng Ke; Jianwen Yang; Tianyi Zhao; Zhaohua Zeng; Yonglie Chen

2006-01-01

65

Room Temperature Hydrosilylation of Silicon Nanocrystals with Bifunctional Terminal Alkenes  

PubMed Central

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

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

2013-01-01

66

Electrocatalysts and Electrode Design for Bifunctional Oxygen/Air Electrodes  

NASA Astrophysics Data System (ADS)

Electrocatalysts and appropriate electrode designs have been studied with respect to the development of Bifunctional Air/Oxygen Electrode (BAE). Three groups of catalysts have been prepared: (i) CuxCo3-xO4; (ii) thin films of Co-Ni-Te-O and Co-Te-O and (iii) CoxOv/ZrO2 films. Different catalysts deposited on classical and originally designed GDE were compared by their electrochemical performances.

Nikolova, V.; Iliev, P.; Petrov, K.; Vitanov, T.; Zhecheva, E.; Stoyanova, R.; Valov, I.; Stoychev, D.

67

Bifunctional air electrodes containing elemental iron powder charging additive  

DOEpatents

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.

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

1982-01-01

68

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

SciTech Connect

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).

Not Available

1991-01-01

69

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

SciTech Connect

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).

Not Available

1991-12-31

70

Rapid decay of unstable Leishmania mRNAs bearing a conserved retroposon signature 3?-UTR motif is initiated by a site-specific endonucleolytic cleavage without prior deadenylation  

PubMed Central

We have previously shown that the Leishmania genome possess two widespread families of extinct retroposons termed Short Interspersed DEgenerated Retroposons (SIDER1/2) that play a role in post-transcriptional regulation. Moreover, we have demonstrated that SIDER2 retroposons promote mRNA degradation. Here we provide new insights into the mechanism by which unstable Leishmania mRNAs harboring a SIDER2 retroposon in their 3?-untranslated region are degraded. We show that, unlike most eukaryotic transcripts, SIDER2-bearing mRNAs do not undergo poly(A) tail shortening prior to rapid turnover, but instead, they are targeted for degradation by a site-specific endonucleolytic cleavage. The main cleavage site was mapped in two randomly selected SIDER2-containing mRNAs in vivo between an AU dinucleotide at the 5?-end of the second 79-nt signature (signature II), which represents the most conserved sequence amongst SIDER2 retroposons. Deletion of signature II abolished endonucleolytic cleavage and deadenylation-independent decay and increased mRNA stability. Interestingly, we show that overexpression of SIDER2 anti-sense RNA can increase sense transcript abundance and stability, and that complementarity to the cleavage region is required for protecting SIDER2-containing transcripts from degradation. These results establish a new paradigm for how unstable mRNAs are degraded in Leishmania and could serve as the basis for a better understanding of mRNA decay pathways in general. PMID:20453029

Müller, Michaela; Padmanabhan, Prasad K.; Rochette, Annie; Mukherjee, Debdutta; Smith, Martin; Dumas, Carole; Papadopoulou, Barbara

2010-01-01

71

Shadow enhancers enable Hunchback bifunctionality in the Drosophila embryo  

PubMed Central

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

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

2015-01-01

72

Shadow enhancers enable Hunchback bifunctionality in the Drosophila embryo.  

PubMed

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

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

2015-01-20

73

Automated Assistance for Designing Active Magnetic Bearings  

NASA Technical Reports Server (NTRS)

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

Imlach, Joseph

2008-01-01

74

Cryogenic turbopump bearing materials  

NASA Technical Reports Server (NTRS)

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.

Bhat, Biliyar N.

1989-01-01

75

Bifunctional aluminum catalyst for CO2 fixation: regioselective ring opening of three-membered heterocyclic compounds.  

PubMed

Regioselective ring opening of three-membered heterocyclic compounds (epoxides or N-substituted aziridines) at various temperatures was observed in coupling reactions with CO2 by the use of an aluminum-salen catalyst in conjunction with intramolecular quaternary ammonium salts as cocatalysts, affording the corresponding five-membered cyclic products with complete configuration retention at the methine carbon. Notably, this bifunctional aluminum-based catalyst exhibited nearly 100% regioselectivity for the ring opening at the methylene C-O bond for various terminal epoxides. This was true for those bearing an electron-withdrawing group, such as styrene oxide or epichlorohydrin, thereby affording the synthesis of various enantiopure cyclic carbonates that have previously been obtained only rarely by other methods. An intramolecular cooperative catalysis is suggested to contribute to the high activity and excellent stereochemistry control observed. Surprisingly, the highly selective ring opening at the methine carbon of N-substituted aziridines was found in the coupling with CO2, predominantly giving 5-substituted oxazolininones with retention of configuration as a result of double inversion at the methine carbon. PMID:25238647

Ren, Wei-Min; Liu, Ye; Lu, Xiao-Bing

2014-10-17

76

Flex bearing UUEC, volume 2  

NASA Technical Reports Server (NTRS)

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.

Clapper, M. L.

1993-01-01

77

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

E-print Network

, this problem is rather difficult to be solved based on the acid electrolyte, even with the Pt-based catalystsAuthor's personal copy A bi-functional cathode structure for alkaline-acid direct ethanol fuel 19 August 2011 Keywords: Fuel cell Alkaline-acid direct ethanol fuel cell Bi-functional structure

Zhao, Tianshou

78

333Biotechnol. Prog. 1995, 11, 333-341 Noncompetitive Immunoassays Using Bifunctional Unilamellar  

E-print Network

333Biotechnol. Prog. 1995, 11, 333-341 Noncompetitive Immunoassays Using Bifunctional Unilamellar the specific signal, the immunoassay protocol was optimized with respect to (1)the type and concentration) the incubation temperature. The bifunctional vesicles were used in a noncompetitive immunoassay to detect d

Kilpatrick, Peter K.

79

The oxidation state of tungsten in iron bearing and iron free silicate glasses: Initial results from W L-edge XANES measurements  

NASA Astrophysics Data System (ADS)

Tungsten is important in constraining core formation of the Earth because this element is a moderately siderophile element (depleted ~ 10 relative to chondrites) and, as a member of the Hf-W isotopic system, it is useful in constraining the timing of core formation. A number of experimental studies have been carried out to determine the silicate solubility and metal-silicate partitioning behavior of W, including its concomitant oxidation state. However, results are inconsistent on whether W occurs as W^{4+} or W^{6+}. Results of Hillgren et al. (1996) and Walter and Thibault (1995) suggest W6+ for oxygen fugacities of IW-1 to -2, whereas Ertel et al. (1996) show W^{4+} for all oxygen fugacities below IW-1. The multiple linear regression analyses of Schmitt et al. (1989) (IW to IW-3) support W^{6+}, while similar analyses by Jones (1998), Lauer and Jones (1999), and Wade and Wood (2005) support W^{4+}, though it was suggested past discrepancies were due to iron-bearing vs. iron free systems. It is assumed that W^{4+} is the cation valence relevant to core formation (Jaeger and Drake, 2000). Given the sensitivity to silicate composition of high valence cations (Jaeger and Drake, 2000), knowledge of the oxidation state of W over a wide range of fO2 is critical to understanding the oxidation state of the mantle and core formation processes. Controlled fO2 experiments were carried out using two compositions to determine the effects of iron content. Experiments were conducted at 1300 °C, for durations of 24 to 72 hours, and air quenched. One series was conducted using the An-Di eutectic, from log fO2 -7.25 to -18. Experiments using an ankaramite starting composition were conducted from log fO2 -1.65 to -18.3. Experiments were doped with 1wt% of WO3. For both starting compositions, at IW-1, one set of experiments was doped with 1wt% of WO2, and at IW+1, one set of experiments was quenched in water. Analyses were conducted using the X-ray absorption near edge structure (XANES) microprobe at the Advanced Photon Source (GeoSoilEnviroCARS), Argonne National Laboratory. A monochromatic X-ray beam from a Si(111) double crystal monochromator was focused onto the sample and the fluorescent X-ray yield was plotted as a function of incident X-ray energy (more detail can be found in Sutton et al., 2002). The oxidation state of tungsten was inferred from the energy of the first peak in the LIII-edge derivative spectrum. WO2, WO3, FeWO4, CaWO4, were used as standards. Results for the CMAS starting materials suggest that only W^{6+} is present from the most oxidized conditions to IW (log fO2 -10.75). At IW-1, W starts to exhibit mixed valence but is still dominated by W^{6+}. At IW-2, W^{4+} becomes more abundant, with the most reduced state observed being equal proportions of W^{4+} and W^{6+}. These preliminary results suggest that W^{6+} may still be present, even below IW-5. At IW-2 and below, metal exsolves from the silicate, complicating the analyses. For ankaramite, only W^{6+} is present down to IW-1, with mixed valence beginning at IW-2, similar behavior to the Fe-free samples. As in the CMAS samples, "the nugget effect" is also observed for the ankaramite glasses below IW-2 and W^{6+} appears to be present below IW-5. Thus, the effect of iron appears to be small, if present at all.

Danielson, L. R.; Righter, K.; Sutton, S.; Newville, M.; Le, L.

2006-12-01

80

Optimal Synchronizability of Bearings  

E-print Network

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 ...

Seybold, Hansjorg

81

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

SciTech Connect

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.

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

1994-05-01

82

Magnetic perturbation inspection of inner bearing races  

NASA Technical Reports Server (NTRS)

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.

Barton, J. R.; Lankford, J.

1972-01-01

83

Interference Fit Life Factors for Roller Bearings  

NASA Technical Reports Server (NTRS)

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.

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

2008-01-01

84

Stability and kinetics of a bifunctional amylase/trypsin inhibitor.  

PubMed

The stability of the bifunctional amylase/trypsin inhibitor from ragi (Indian finger millet, Eleusine coracana) has been studied by methods of circular dichroism, UV absorption and intrinsic fluorescence. The inhibitor is stable in 8 M urea and 6 M guanidine-HCl. In 150 mM NaCl, thermal denaturation does not occur up to 90 degrees C. However, it is irreversibly denatured in 5 mM NaCl if heated over 73 degrees C. The acidic denaturation is reversible in both high and low salt conditions, but it shows different behavior below pH 1.65 under similar salt conditions. The helical content is about 2-4% in the pH range of 7-9 at which the inhibitor is active maximally. The NaCl concentration does not have a significant effect on the secondary structure elements. The beta-strand form does not show much variation under various conditions. Arg34-Leu35 is the reactive peptide bond in the trypsin-binding site. Trp and Tyr are involved in the binding with amylase. The bifunctional inhibitor represents the sum of individual inhibitors of trypsin and amylase. PMID:7692971

Alagiri, S; Singh, T P

1993-11-10

85

Photovoltachromic device with a micropatterned bifunctional counter electrode.  

PubMed

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

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

2014-02-26

86

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

NASA Astrophysics Data System (ADS)

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

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

2015-01-01

87

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

SciTech Connect

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.

Klein, M.; Viswanathan, S.

1986-12-01

88

Bearings for Your Whirligig  

NSDL National Science Digital Library

Experiment with friction and make bearings for a whirligig! This activity is a nice introduction to friction and bearings and demonstrates why bearings are useful for spinning. A related video show Vollis Simpson, an artist who creates kinetic sculptures and whirligigs, explain how he uses bearings in all of his spinning pieces so that they move smoothly.

Science Musuem of Minnesota

1995-01-01

89

Passive magnetic bearing configurations  

DOEpatents

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.

Post, Richard F. (Walnut Creek, CA)

2011-01-25

90

Getting Your Bearings  

NSDL National Science Digital Library

In this activity, learners explore the concept of friction and how ball bearings reduce friction. Learners investigate different uses for ball bearings, how the design has changed over time to incorporate roller bearings, test friction using marbles, and identify the use of ball bearings in everyday items.

IEEE

2013-08-30

91

Cryogenic foil bearing turbopumps  

NASA Technical Reports Server (NTRS)

Cryogenic foil bearing turbopumps offer high reliability and low cost. The fundamental cryogenic foil bearing technology has been validated in both liquid hydrogen and liquid oxygen. High load capacity, excellent rotor dynamics, and negligible bearing wear after over 100 starts and stops, and over many hours of testing, were observed in both fluids. An experimental liquid hydrogen foil bearing turbopump was also successfully demonstrated. The results indicate excellent stability, high reliability, wide throttle-ability, low bearing cooling flow, and two-phase bearing operability. A liquid oxygen foil bearing turbopump has been built and is being tested at NASA MSFC.

Gu, Alston L.

1993-01-01

92

Rolling-Element Bearings  

NASA Technical Reports Server (NTRS)

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.

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

1983-01-01

93

Introduction to ball bearings  

NASA Technical Reports Server (NTRS)

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.

Hamrock, B. J.; Dowson, D.

1981-01-01

94

High efficiency magnetic bearings  

NASA Technical Reports Server (NTRS)

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.

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

1993-01-01

95

The bi-functional organization of human basement membranes.  

PubMed

The current basement membrane (BM) model proposes a single-layered extracellular matrix (ECM) sheet that is predominantly composed of laminins, collagen IVs and proteoglycans. The present data show that BM proteins and their domains are asymmetrically organized providing human BMs with side-specific properties: A) isolated human BMs roll up in a side-specific pattern, with the epithelial side facing outward and the stromal side inward. The rolling is independent of the curvature of the tissue from which the BMs were isolated. B) The epithelial side of BMs is twice as stiff as the stromal side, and C) epithelial cells adhere to the epithelial side of BMs only. Side-selective cell adhesion was also confirmed for BMs from mice and from chick embryos. We propose that the bi-functional organization of BMs is an inherent property of BMs and helps build the basic tissue architecture of metazoans with alternating epithelial and connective tissue layers. PMID:23844050

Halfter, Willi; Monnier, Christophe; Müller, David; Oertle, Philipp; Uechi, Guy; Balasubramani, Manimalha; Safi, Farhad; Lim, Roderick; Loparic, Marko; Henrich, Paul Bernhard

2013-01-01

96

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

PubMed

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

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

2015-03-11

97

The Bi-Functional Organization of Human Basement Membranes  

PubMed Central

The current basement membrane (BM) model proposes a single-layered extracellular matrix (ECM) sheet that is predominantly composed of laminins, collagen IVs and proteoglycans. The present data show that BM proteins and their domains are asymmetrically organized providing human BMs with side-specific properties: A) isolated human BMs roll up in a side-specific pattern, with the epithelial side facing outward and the stromal side inward. The rolling is independent of the curvature of the tissue from which the BMs were isolated. B) The epithelial side of BMs is twice as stiff as the stromal side, and C) epithelial cells adhere to the epithelial side of BMs only. Side-selective cell adhesion was also confirmed for BMs from mice and from chick embryos. We propose that the bi-functional organization of BMs is an inherent property of BMs and helps build the basic tissue architecture of metazoans with alternating epithelial and connective tissue layers. PMID:23844050

Halfter, Willi; Monnier, Christophe; Müller, David; Oertle, Philipp; Uechi, Guy; Balasubramani, Manimalha; Safi, Farhad; Lim, Roderick; Loparic, Marko; Henrich, Paul Bernhard

2013-01-01

98

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

DOEpatents

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.

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

2003-10-21

99

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...

100

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

DOEpatents

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.

Lucas, Joe N. (San Ramon, CA); Straume, Tore (Tracy, CA); Bogen, Kenneth T. (Walnut Creek, CA)

2000-01-01

101

6-Phosphofructo-2-kinase/fructose-2,6-bisphosphatase: head-to-head with a bifunctional enzyme that controls glycolysis  

PubMed Central

Fru-2,6-P2 (fructose 2,6-bisphosphate) is a signal molecule that controls glycolysis. Since its discovery more than 20 years ago, inroads have been made towards the understanding of the structure–function relationships in PFK-2 (6-phosphofructo-2-kinase)/FBPase-2 (fructose-2,6-bisphosphatase), the homodimeric bifunctional enzyme that catalyses the synthesis and degradation of Fru-2,6-P2. The FBPase-2 domain of the enzyme subunit bears sequence, mechanistic and structural similarity to the histidine phosphatase family of enzymes. The PFK-2 domain was originally thought to resemble bacterial PFK-1 (6-phosphofructo-1-kinase), but this proved not to be correct. Molecular modelling of the PFK-2 domain revealed that, instead, it has the same fold as adenylate kinase. This was confirmed by X-ray crystallography. A PFK-2/FBPase-2 sequence in the genome of one prokaryote, the proteobacterium Desulfovibrio desulfuricans, could be the result of horizontal gene transfer from a eukaryote distantly related to all other organisms, possibly a protist. This, together with the presence of PFK-2/FBPase-2 genes in trypanosomatids (albeit with possibly only one of the domains active), indicates that fusion of genes initially coding for separate PFK-2 and FBPase-2 domains might have occurred early in evolution. In the enzyme homodimer, the PFK-2 domains come together in a head-to-head like fashion, whereas the FBPase-2 domains can function as monomers. There are four PFK-2/FBPase-2 isoenzymes in mammals, each coded by a different gene that expresses several isoforms of each isoenzyme. In these genes, regulatory sequences have been identified which account for their long-term control by hormones and tissue-specific transcription factors. One of these, HNF-6 (hepatocyte nuclear factor-6), was discovered in this way. As to short-term control, the liver isoenzyme is phosphorylated at the N-terminus, adjacent to the PFK-2 domain, by PKA (cAMP-dependent protein kinase), leading to PFK-2 inactivation and FBPase-2 activation. In contrast, the heart isoenzyme is phosphorylated at the C-terminus by several protein kinases in different signalling pathways, resulting in PFK-2 activation. PMID:15170386

2004-01-01

102

A mechanistic study of methyl parathion hydrolysis by a bifunctional organoclay.  

PubMed

The mechanism for the hydrolysis of methyl parathion (MP) by a bifunctional quaternary-ammonium based long-chained organclay(LCOC) containing an alkylamine (-CH2CH2-NH2) headgroup was elucidated. The pathway of the catalytic hydrolysis of methyl parathion by the LCOC was defined by following the effect of replacing H20 with D20, by replacing the primary amino headgroup by a tertiary amino group, and by a detailed mathematical analysis of the proposed reaction scheme. A phosphorothioate isomer of MP was formed in the presence of the LCOC as an intermediate reaction product, initially increasing in concentration and then disappearing. The isotope effect was minimal and substituting a tertiary amine in the LCOC increased the rate of MP hydrolysis. A mechanism is proposed in which hydrolysis of MP can proceed via both a direct route (specific base hydrolysis) and through the formation of the isomer which then undergoes specific base hydrolysis more rapidly than the parent MP. The relative importance of each pathway is a function of pH with the direct hydrolysis of MP being predominant at higher pH values (pH > 10) and the isomer intermediate pathway predominating at lower pH values (pH approximately 8-10). PMID:17265934

Rav-Acha, Chaim; Groisman, Ludmila; Mingelgrin, Uri; Kirson, Zvi; Sasson, Yoel; Gerstl, Zev

2007-01-01

103

Mechanical spin bearings  

NASA Technical Reports Server (NTRS)

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.

Vranish, John M. (Inventor)

1998-01-01

104

Tracking Polar Bears  

NSDL National Science Digital Library

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

2008-01-17

105

Conferring flame retardancy on cotton using novel halogen-free flame retardant bifunctional monomers: synthesis, characterizations and applications.  

PubMed

Two novel halogen-free phosphorous-nitrogen flame retardant bifunctional monomers were synthesized and characterized using attenuated total reflectance/Fourier transform-infrared (ATR/FT-IR) and electrospray ionization mass spectrometry ((+)ESI-MS). The monomers were applied separately and graft polymerized on cotton in the presence of the thermal initiator K(2)S(2)O(8). The performance of each monomer was evaluated using thermal gravimetric analysis (TGA), grafting efficiency, and vertical flame test. It was shown that the performance of N,N-dimethyl di(acryloyloxyethyl)phosphoramide (DMDAEP) (monomer 2) as flame retardant outperformed that of ethyl di(acryloyloxyethyl)phosphorodiamidate (EDAEP) (monomer 1). The superior performance of DMDAEP was attributed to the presence of more nitrogen atoms compared to EDAEP. The increased nitrogen content in DMDAEP increased the synergistic effect of the P-N system. Cotton treated using padding methods showed more promising results than cotton treated by exhaust methods. PMID:23218381

Cheema, Hammad A; El-Shafei, Ahmed; Hauser, Peter J

2013-01-30

106

Polar Bears Change Diet  

NSDL National Science Digital Library

This radio broadcast from 2001 explains how polar bears have adjusted their diet due to the climate warming around Hudson Bay, Canada. The ringed seals that polar bears normally eat have been harder for polar bears to get to, due to disappearing ice. This has forced polar bears to begin eating harbor seals and bearded seals. The clip is 4 minutes and 15 seconds in length.

Doug Schneider

2007-12-12

107

Axial Halbach Magnetic Bearings  

NASA Technical Reports Server (NTRS)

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.

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

2008-01-01

108

Tracking Polar Bears  

USGS Multimedia Gallery

Movements of 9 satellite-collared adult female polar bears were tracked in February, 2010 by satellite telemetry. Bears were collared in 2007, 2008, and 2009 on the spring-time sea ice of the southern Beaufort Sea or on the autumn pack ice in 2009. Polar bear satellite telemetry data are shown with ...

109

Grizzly bears and forestry  

Microsoft Academic Search

Today's growing demand for timber is increasing road development in once roadless forest ecosystems. Roads create both local changes in plant communities and landscape-level changes in forest connectivity. Roads also increase human access, which can be detrimental to species such as grizzly bears. Because most grizzly bear mortalities occur near roads, we examined grizzly bear attractants near roads, which could

C. L. Roever; M. S. Boyce; G. B. Stenhouse

2008-01-01

110

1-Way Bearing  

NASA Technical Reports Server (NTRS)

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.

Vranish, John M. (Inventor)

2003-01-01

111

Status of Understanding for Bearing Materials  

NASA Technical Reports Server (NTRS)

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.

Bamberger, E. N.

1984-01-01

112

Cryogenic Hybrid Magnetic Bearing  

NASA Technical Reports Server (NTRS)

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.

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

1994-01-01

113

Bearing strength of carbon fibre\\/epoxy laminates: effects of bolt-hole clearance  

Microsoft Academic Search

The bearing strength of carbon fibre epoxy laminates manufactured from non-crimp fabric from heavy tow yarn has been investigated. The effects of laminate stacking sequence and geometry on the bearing strength have been determined experimentally together with the effect of initial bolt-hole clearance on the bearing strength at 4% hole deformation and at ultimate load. Significant reduction in bearing strength

Gordon Kelly; Stefan Hallström

2004-01-01

114

Magnetic-plasmonic bifunctional CoO-Ag heterostructure nanoparticles  

NASA Astrophysics Data System (ADS)

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

Yang, Jianhui; Cao, Beibei; Liu, Bin

2014-03-01

115

Gold-Copper Nanoparticles: Nanostructural Evolution and Bifunctional Catalytic Sites  

SciTech Connect

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

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

2012-12-12

116

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

PubMed Central

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

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

2013-01-01

117

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

SciTech Connect

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

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

1997-01-01

118

One-pot synthesis of Ir@Pt nanodendrites as highly active bifunctional electrocatalysts for oxygen reduction and oxygen evolution in acidic medium  

E-print Network

One-pot synthesis of Ir@Pt nanodendrites as highly active bifunctional electrocatalysts for oxygen regenerative fuel cell Bifunctional electrocatalyst Nanodendrite Core-shell Iridium Platinum Nanodendritic Ir time. Besides good dispersion and uniform composition distribution, Ir@Pt bifunctional electro

Liu, Fuqiang

119

Bearings: Technology and needs  

NASA Technical Reports Server (NTRS)

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.

Anderson, W. J.

1982-01-01

120

The Incredible Water Bear  

NSDL National Science Digital Library

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

Martin Mach

121

Robust and intelligent bearing estimation  

SciTech Connect

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. The lowest measurable frequency in the dispersion pattern is often a near error free bearing. These latter features should be helpful in calibrating the stations for frequency dependent biases induced by the earth. Future efforts will enhance the SEE algorithm and will also evaluate it using larger station data sets.

Claassen, J.P.

1998-07-01

122

Bearing restoration by grinding  

NASA Technical Reports Server (NTRS)

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.

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

1976-01-01

123

Linear magnetic bearing  

NASA Technical Reports Server (NTRS)

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.

Studer, P. A. (inventor)

1983-01-01

124

A practical magnetic bearing  

NASA Technical Reports Server (NTRS)

A small compact magnetic bearing design developed and tested features a bearing capable of supporting over ten times its own weight, dimensioned 8 cm diam by 3.75 cm, with rare-earth cobalt magnets. Only 1% of the device payload figures as part of the magnetic suspension. The design is servoed in two axes and exhibits inherent stability in three more degrees of freedom, with full rotational freedom in the desired axis. Capacitive radial gap sensing allows stiff servoing of the rotation axis. Differential sensing and EM control linearize control functions. Low power drain, simple fabrication and assembly, and larger clearances than in air bearings or ball bearings are reported

Studer, P. A.

1977-01-01

125

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

SciTech Connect

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.

Alexandratos, S. D.

2001-06-01

126

Laccase-mediated oxidation of small organics: bifunctional roles for versatile applications.  

PubMed

Laccases have been widely used in several biotechnological areas, including organic synthesis, bioremediation, and pulp/textile bleaching. In most applications, the enzymatic actions start with single-electron oxidation of small organics followed by formation of the corresponding radicals. These radicals are subsequently involved in either oxidative coupling (i.e., bond formation) or bond cleavage of target organics. These bifunctional actions--catabolic versus anabolic--are readily identifiable in in vivo metabolic processes involving laccases. Here, we characterize the bifunctionality of laccase-mediated oxidation of small organics and present the view that knowledge of the biological functions of these metabolic processes in vivo can illuminate potential biotechnological applications of this bifunctionality. PMID:23639526

Jeon, Jong-Rok; Chang, Yoon-Seok

2013-06-01

127

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

SciTech Connect

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.

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

2012-03-15

128

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

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

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

2013-01-01

129

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

PubMed

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

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

2013-02-01

130

Past Performance analysis of HPOTP bearings  

NASA Technical Reports Server (NTRS)

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.

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

1982-01-01

131

Bioconjugates of rhizavidin with single domain antibodies as bifunctional immunoreagents.  

PubMed

Use of the avidin-biotin binding interaction for immunoassay applications is widespread. One advantageous immunoreagent is the recombinant fusion of an antibody fragment with a biotin binding protein. These genetic fusions alleviate the need to prepare chemical conjugates to achieve molecules that combine target recognition with signal transduction or to facilitate the directional immobilization of the binding element. In order for such a fusion protein to be useful, however, it must be able to be produced in good yield. Unfortunately, recombinant production of avidin or streptavidin as well as bioconjugates derived thereof has been problematic. An alternative biotin binding molecule called rhizavidin has been described, which forms a homodimer instead of a tetramer, but it has not been evaluated in genetic fusions with antibody binding domains. Single domain antibodies, the variable domain derived from camelid heavy chain only antibodies, offer binding domains with high affinity, and solubility that are well expressed in Escherichia coli. In this work, we prepared an anti-ricin single domain antibody - rhizavidin bioconjugate and evaluated it on the basis of its production in E. coli and on its activity in comparison to a streptavidin core bioconjugate and unfused single domain antibody. The single domain antibody-rhizavidin bioconjugate produced much better than its streptavidin core counterparts, yielding an average of 14 mg/L, a 20-fold improvement. When used in assays the rhizavidin conjugate provided the same desirable characteristics as the streptavidin core fusion as both capture and detection reagents. Since rhizavidin and single domain antibodies both display impressive thermal stabilities their fusion provides a route to achieve robust bifunctional immunoreagents. PMID:24946086

Liu, Jinny L; Zabetakis, Dan; Walper, Scott A; Goldman, Ellen R; Anderson, George P

2014-09-01

132

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

NASA Astrophysics Data System (ADS)

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

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

2014-02-01

133

Synthesis and characterization of hafnium and molybdenum bifunctional initiators for the preparation of triblock copolymers  

E-print Network

Chapter 1. Three monofunctional mixed alkyl hafnium complexes containing the (MesNpy)2 ligand ([(MesitylNCH2)2CMe(2-CsH4N)]2) were synthesized. (MesNpy)Hf(Neo)R ((2b), R = Me; Neo = CH2CMe2Ph) and (MesNpy)Hf(CH2TMS)(R), ...

Gabert, Andrea Jennifer

2007-01-01

134

Characterization of the bisintercalative DNA binding mode of a bifunctional platinum–acridine agent  

PubMed Central

The DNA interactions of PT-BIS(ACRAMTU) ([Pt(en)(ACRAMTU)2](NO3)4; ACRAMTU = 1-[2-(acridin-9-ylamino)ethyl]-1,3-dimethylthiourea, en = ethylenediamine), a bifunctional platinum–acridine conjugate, have been studied in native and synthetic double-stranded DNAs and model duplexes using various biophysical techniques. These include ethidium-DNA fluorescence quenching and thermal melting experiments, circular dichroism (CD) spectroscopy and plasmid unwinding assays. In addition, the binding mode was studied in a short octamer by NMR spectroscopy in conjunction with molecular modeling. In alternating copolymers, PT-BIS(ACRAMTU) shows a distinct preference for poly(dA-dT)2, which is ?3-fold higher than that of ACRAMTU. In the ligand-oligomer complex, d(GCTATAGC)2·PT-BIS(ACRAMTU) (complex I*), PT-BIS(ACRAMTU) increases the thermal stability of the B-form host duplex by ?Tm > 30 K (CD and UV melting experiments). The agent unwinds pSP73 plasmid DNA by 44(±2)° per bound molecule, indicating bisintercalative binding. A 2-D NMR study unequivocally demonstrates that PT-BIS(ACRAMTU)'s chromophores deeply bisintercalate into the 5?-TA/TA base pair steps in I*, while the platinum linker lies in the minor groove. An AMBER model reflecting the NMR results shows that bracketing of the central AT base pairs in a classical nearest neighbor excluded fashion is feasible. PT-BIS(ACRAMTU) inhibits DNA hydrolysis by BstZ17 I at the enzyme's restriction site, GTA?TAC. Possible consequences for other relevant DNA–protein interactions, such as those involved in TATA-box-mediated transcription initiation and the utility of the platinum-intercalator technology for the design of sequence-specific agents are discussed. PMID:16192574

Choudhury, Jayati Roy; Bierbach, Ulrich

2005-01-01

135

AX-5 space suit bearing torque investigation  

NASA Technical Reports Server (NTRS)

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.

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

1990-01-01

136

Bearing servicing tool  

NASA Technical Reports Server (NTRS)

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.

Boyce, Rex A. (inventor)

1992-01-01

137

Grizzly bears and forestry  

Microsoft Academic Search

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

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

2004-01-01

138

Grizzly bears and forestry  

Microsoft Academic Search

Timber harvesting and oil and gas extraction create ecological change beyond just the footprint of the resource extraction. These activities also create a permanent network of roads that can have lasting effects on forest ecology. Grizzly bears (Ursus arctos) suffer higher mortality when in close proximity to roads, yet bears in the foothills of west-central Alberta, continue to use these

C. L. Roever; M. S. Boyce; G. B. Stenhouse

2008-01-01

139

ALASKAN POLAR BEAR DENNING  

Microsoft Academic Search

Abstract: Information on 35 overwinter maternity dens of Alaskan polar bears (Ursus maritimnus Phipps) and on 101 female polar bears with cubs, recently emerged from dens, was obtained by aerial and ground surveys, interviews with Arctic coast residents, and literature review. Pregnant females form snow dens in October and November and give birth in December and January. Females and cubs

Jack W. Lentfer; Richard J. Hensel

140

Magnetic bearing applications & economics  

Microsoft Academic Search

Magnetic bearings offer a myriad of operational advantages and efficiency improvement over traditional oil lubricated bearings. They have been in use for the past thirty years, but for several reasons, including cost, have been limited to niche applications (such as high-speed turbomachines) that required their unique capabilities. Recent advances in the technology are making it more practical to apply these

D. Eaton; J. Rama; S. Singhal

2010-01-01

141

Operation of a Microfabricated High Speed Gas Bearing  

NASA Astrophysics Data System (ADS)

As with large scale engines, the MIT microfabricated gas turbine engine requires high speed rotating components to achieve useful levels of power density and efficiency. The gas bearing flows in this microengine have much larger Mach and Reynolds numbers than conventional scale gas bearing flows. Due to microfabrication constraints, the aspect ratio of this bearing also differs significantly from the common design space. A microfabricated test device has been designed and fabricated to study gas lubricated bearings on the microscale. The bearing test device consists of a bonded stack of five silicon wafers. A 4 mm diameter, 450 ?m thick rotor is captured within the device. The rotor is driven by an air turbine. Hydrostatic thrust bearings support the rotor axially; a coupled hydrostatic/hydrodynamic journal bearing supports the rotor radially. A rotation rate of 500,000 rpm has been achieved in initial tests. Results from operation of this microbearing test device will be presented.

Jacobson, S. A.; Ehrich, F. F.; Fréchette, L. G.; Lin, C. C.; Breuer, K. S.

1999-11-01

142

Study of Catcher Bearings for High Temperature Magnetic Bearing Application  

E-print Network

temperature permanent magnet based magnetic bearings. The magnetic bearings are made of high temperature resistant permanent magnets (up to 1000 degrees F). A test rig has been developed to test these magnetic bearings. The test rig mainly consists of two...

Narayanaswamy, Ashwanth

2011-08-08

143

Touchdown Ball-Bearing System for Magnetic Bearings  

NASA Technical Reports Server (NTRS)

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).

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

2003-01-01

144

Ball and Roller Bearings. A Teaching Reference.  

ERIC Educational Resources Information Center

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)…

American Association for Vocational Instructional Materials, Athens, GA.

145

Magnetically-controlled bearing lubrication  

NASA Technical Reports Server (NTRS)

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.

Whitaker, A. F.

1977-01-01

146

Bifunctional highly fluorescent hollow porous microspheres made of BaMoO4 : Pr3+  

E-print Network

Bifunctional highly fluorescent hollow porous microspheres made of BaMoO4 : Pr3+ nanocrystals via hollow porous microsphere composed of single-component BaMoO4 : Pr3+ nanocrystals by a facile template-free synthesis. All the as-synthesized hollow microspheres are well- dispersed with a diameter of 2­4 mm

Demir, Hilmi Volkan

147

Preparation of bifunctional hybrid mesoporous silica potentially useful for drug targeting  

Microsoft Academic Search

Bifunctional hybrid mesoporous silica potentially useful for drug targeting has been synthesized starting from neutral surfactant-templated mesoporous silica. A receptor specific ligand folic acid, in principle able to be recognized from specific tissues, has been covalently coupled on the external function of as-synthesized mesoporous silica thanks to the presence of aminopropyl groups. A series of hybrid materials useful to investigate

Luigi Pasqua; Flaviano Testa; Rosario Aiello; Sante Cundari; Janos B. Nagy

2007-01-01

148

Crossing the threshold from accelerated substitution to elimination with a bifunctional macrocyclewz  

E-print Network

Crossing the threshold from accelerated substitution to elimination with a bifunctional. This present study examines the reactivity with 1,2-disubstituted ethanes. Accelerated substitution is observed elimination is the outcome with 3-halopropionitriles (10 000 times faster than analogous control amines

Smith, Bradley D.

149

Crystal Structure of the Bifunctional ATP Sulfurylase APS kinase from the Chemolithotrophic  

E-print Network

and adenosine-5-phosphosul- fate (APS) kinase activities. These enzymes are usually segregated on two separate-phosphoadenosine-5- phosphosulfate; ATS, ATP sulfurylase; APS, adenosine-5- phosphosulfate; ASK, APS kinase. ECrystal Structure of the Bifunctional ATP Sulfurylase ­ APS kinase from the Chemolithotrophic

Fisher, Andrew J.

150

Formation of ceramophilic chitin and biohybrid materials enabled by a genetically engineered bifunctional protein.  

PubMed

A bifunctional protein composed of a highly negatively charged oyster shell protein and a chitin-binding domain enabled the formation of biohybrid materials through non-covalent surface modification of chitin nanofibres. The results demonstrate that specific biomolecular interactions offer a route for the formation of biosynthetic materials. PMID:24871427

Malho, Jani-Markus; Heinonen, Hanna; Kontro, Inkeri; Mushi, Ngesa E; Serimaa, Ritva; Hentze, Hans-Peter; Linder, Markus B; Szilvay, Géza R

2014-07-14

151

Hydrodeoxygenation and coupling of aqueous phenolics over bifunctional zeolite-supported metal catalysts.  

PubMed

Pt supported on HY zeolite is successfully used as a bifunctional catalyst for phenol hydrodeoxygenation in a fixed-bed configuration at elevated hydrogen pressures, leading to hydrogenation-hydrogenolysis ring-coupling reactions producing hydrocarbons, some with enhanced molecular weight. PMID:20126705

Hong, Do-Young; Miller, Stephen J; Agrawal, Pradeep K; Jones, Christopher W

2010-02-21

152

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

PubMed

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

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

2011-12-01

153

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

E-print Network

Bifunctional Lewis Acid-Nucleophile-Based Asymmetric Catalysis: Mechanistic Evidence for Imine. Chiral cinchona alkaloid derivatives work best when paired with Lewis acids based on Al(III), Zn(II), Sc, particularly in the case of traditionally slow reactions. Theoretically, the use of a Lewis acid and a (1) (a

Lectka, Thomas

154

Simple coordination complex-derived three-dimensional mesoporous graphene as an efficient bifunctional oxygen electrocatalyst.  

PubMed

3D mesoporous graphene (mesoG) was synthesized from [Ni2(EDTA)] (EDTA = ethylenediaminetetraacetate). The material is comprised of interconnected 4 nm-sized hollow carbon shells composed of 3-4 layers of graphene and exhibits high bifunctional electrocatalytic activity as well as high durability for use in oxygen evolution and reduction reactions. PMID:25785568

Lee, Kyung Joo; Sa, Young Jin; Jeong, Hu Young; Bielawski, Christopher W; Joo, Sang Hoon; Moon, Hoi Ri

2015-04-01

155

Charge conductivity in peptides: Dynamic simulations of a bifunctional model supporting experimental data  

PubMed Central

Our previous finding and the given mechanism of charge and electron transfer in polypeptides are here integrated in a bifunctional model involving electronic charge transfer coupled to special internal rotations. Present molecular dynamics simulations that describe these motions in the chain result in the mean first passage times for the hopping process of an individual step. This “rest and fire” mechanism is formulated in detail—i.e., individual amino acids are weakly coupled and must first undergo alignment to reach the special strong coupling. This bifunctional model contains the essential features demanded by our prior experiments. The molecular dynamics results yield a mean first passage time distribution peaked at about 140 fs, in close agreement with our direct femtosecond measurements. In logic gate language this is a strongly conducting ON state resulting from small firing energies, the system otherwise being a quiescent OFF state. The observed time scale of about 200 fs provides confirmation of our simulations of transport, a model of extreme transduction efficiency. It explains the high efficiency of charge transport observed in polypeptides. We contend that the moderate speed of weak coupling is required in our model by the bifunctionality of peptides. This bifunctional mechanism agrees with our data and contains valuable features for a general model of long-range conductivity, final reactivity, and binding at a long distance. PMID:10655485

Schlag, E. W.; Sheu, Sheh-Yi; Yang, Dah-Yen; Selzle, H. L.; Lin, S. H.

2000-01-01

156

Dimerization and Bifunctionality Confer Robustness to the Isocitrate Dehydrogenase Regulatory System in Escherichia  

E-print Network

robustness. E. coli IDH is regulated by reversible phosphorylation catalyzed by the bifunctional isocitrate is directed through the glyoxylate bypass (for growth on two-carbon substrates) or the full tricarboxylic acid realistic models in systems biology. During growth on a two-carbon substrate, Escherichia coli diverts

Gunawardena, Jeremy

157

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

PubMed

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

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

2014-03-01

158

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

PubMed Central

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

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

2012-01-01

159

Vinyl sulfone bifunctional derivatives of DOTA allow sulfhydryl- or amino-directed coupling to antibodies. Conjugates retain immunoreactivity and have similar biodistributions.  

PubMed

We have synthesized a bifunctional vinyl sulfone-cysteineamido derivative of DOTA (1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid) that can be conjugated to the sulfhydryls of mildly reduced recombinant antibody (chimeric anti-CEA antibody cT84.66) at pH 7 or to the amino groups of lysine residues at pH 9. The conjugation is sulfhydryl specific at pH 7 (case 1), and amino specific at pH 9 (case 2) as long as the antibody has no free sulhydryl groups. At a molar ratio of 50 BCA (bifunctional chelating agent) to mAb, the number of chelates conjugated is 0.8 for case 1, and 4.6 for case 2. The resulting conjugates can be radiolabeled with (111)In to high specific activity (5 mCi/mg) with high efficiency (>95%) at 43 degrees C in 60 min. The radiolabeled conjugates retained >95% immunoreactivity and are stable in serum containing 1mM DTPA over 3 d. When the radiolabeled conjugates were injected into nude mice bearing LS174T human colon tumor xenografts, over 40% ID/g accumulated in tumors during the period 24-72h. Tumor-to-blood ratios were 4.5, 3.5, and 2.5 for the sulfhydryl coupled conjugate at 24, 48, and 72 h, respectively, and 2.7, 2.5, and 2.3 for the amino-coupled conjugate at the same time points. For other organs the biodistributions were nearly identical whether the conjugates were attached via sulfhydryl or amino groups. These novel BCAs are easy to synthesize, offer versatile conjugation options, and give equivalent biodistributions that result in high tumor uptake and good tumor-to-blood ratios. PMID:11792185

Li, Lin; Tsai, Shih-Wa; Anderson, Anne-Line; Keire, David A; Raubitschek, Andrew A; Shively, John E

2002-01-01

160

The Polar Bear Tracker  

NSDL National Science Digital Library

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

161

Ball Bearing Mechanics  

NASA Technical Reports Server (NTRS)

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.

Hamrock, B. J.; Dowson, D.

1981-01-01

162

Roller bearing geometry design  

NASA Technical Reports Server (NTRS)

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.

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

1976-01-01

163

Protecting Bear While Tranqualized  

USGS Multimedia Gallery

The kerchief over the bear's eyes protects it from dust and debris and reduces visual stimulation. The small tubing in its nose, known as a nasal cannula, delivers oxygen to the animal while it is tranquilized....

164

PCs and Polar Bears  

NSDL National Science Digital Library

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

Jessica Fries-Gaither

2011-01-01

165

Optimal Synchronizability of Bearings  

NASA Astrophysics Data System (ADS)

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

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

2013-02-01

166

Rocketdyne LOX bearing tester program  

NASA Technical Reports Server (NTRS)

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.

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

1988-01-01

167

Investigation of Pressurized Wave Bearings  

NASA Technical Reports Server (NTRS)

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.

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

2003-01-01

168

Gear bearing drive  

NASA Technical Reports Server (NTRS)

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.

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

2011-01-01

169

Load responsive hydrodynamic bearing  

DOEpatents

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.

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

2002-01-01

170

Simple modeling of hydrostatic bearings  

NASA Astrophysics Data System (ADS)

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.

Hull, Charlie

2014-07-01

171

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...

172

American Black Bear: Ursus americanus  

E-print Network

3/21/2011 1 USFWS American Black Bear: Ursus americanus www.bear.org LDWF Historic Distribution Bear: Ursus americanus Louisiana Florida Eastern Olympic New Mexico California Cinnamon Mexican: Ursus americanus luteolus American black bear Historically abundant in Louisiana, eastern Texas

Gray, Matthew

173

Externally Pressurized Porous Thrust Bearings  

Microsoft Academic Search

The use of porous material in the bearing surface of externally pressurized thrust bearings leads to a compact design by eliminating the need for an external restrictor and has other potential advantages.An experimental and theoretical investigation of the performance of such bearings, using liquid lubricants is described: the investigation is limited to static conditions but considers the effect of bearing

R. B. Howarth

1976-01-01

174

Production of rat soluble and membrane-bound catechol O-methyltransferase forms from bifunctional mRNAs.  

PubMed Central

In the rat, the catechol O-methyltransferase (COMT) gene has been found to contain two promoters, P1 and P2. This organization enables the gene to produce a soluble (S-COMT) and a membrane-associated (MB-COMT) protein by using two in-frame ATG initiation codons (S- and MB-ATG). The P1 promoter expresses a 1.6 kb transcript (S-mRNA) which codes for the S-COMT polypeptide only. Here we demonstrate that the P2 promoter controls the expression of alternatively spliced 1.9 kb transcripts (MB-mRNA) which differ by a 27-nucleotide region immediately upstream of the MB-AUG codon. The presence of the 27-base sequence alters the nucleotide at position -3 from G to C, thereby changing the translation initiation context of the MB-AUG codon. Expression experiments in COS-7 cells using full-length COMT cDNAs showed that this alteration affected the initiation of the translation of the MB-AUG and consequently changed the relative amounts of MB- and S-COMT polypeptides produced. No proteolytic cleavage of the MB-COMT form to S-COMT was detected in in vitro or in vivo pulse-chase experiments. We conclude that the bifunctional 1.9 kb mRNAs are able to produce both S-COMT and MB-COMT polypeptide by the leaky scanning mechanism of translation initiation. Images Figure 1 Figure 4 Figure 5 PMID:8280056

Tenhunen, J; Ulmanen, I

1993-01-01

175

Preparation and characteristics of Fe 3O 4@YVO 4:Eu 3+ bifunctional magnetic–luminescent nanocomposites  

Microsoft Academic Search

A facile direct precipitation method has been developed for the synthesis of bifunctional magnetic–luminescent nanocomposites with Fe3O4 nanoparticles as the core and YVO4:Eu3+ as the shell. Transmission electron microscopy (TEM) images revealed that the obtained bifunctional nanocomposites had a core–shell structure and a spherical morphology. The average size was ?150nm, and the thickness of the shell was ?15nm. The X-ray

Hongxia Peng; Guixia Liu; Xiangting Dong; Jinxian Wang; Jia Xu; Wensheng Yu

2011-01-01

176

Magnetic, luminescent and core–shell structured Fe 3O 4@YF 3:Ce 3+,Tb 3+ bifunctional nanocomposites  

Microsoft Academic Search

Bifunctional magnetic–luminescent nanocomposites with Fe3O4 nanoparticles as the cores and YF3:Ce3+,Tb3+ as the shells were synthesized by a facile direct precipitation method. Transmission electron microscopy (TEM) images revealed that the obtained bifunctional nanocomposites had a core–shell structure, in a spherical shape with a size ranging from 160 to 220nm, and the shell thickness of about 25nm. The X-ray diffraction (XRD)

Hongxia Peng; Guixia Liu; Xiangting Dong; Jinxian Wang; Wensheng Yu; Jia Xu

177

Molecular changes in the d -bifunctional protein cDNA sequence in australasian patients belonging to the bifunctional protein complementation group  

Microsoft Academic Search

The cDNA sequence for the human d-bifunctional protein (D-BP: 17?-hydroxysteroid dehydrogenase IV) was investigated in patients with peroxisomal disorders\\u000a belonging to the BP complementation group (CG). In three cases, analysis of polymerase chain reaction products generated from\\u000a the patients' cDNA indicated the presence of a deletion within the region corresponding to nucleotides 209–537 of the normal\\u000a cDNA sequence. Subsequent sequencing

Barbara C. Paton; Anthony N. Pollard

2000-01-01

178

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

Code of Federal Regulations, 2011 CFR

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

2011-10-01

179

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

Code of Federal Regulations, 2010 CFR

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

2010-10-01

180

78 FR 70515 - Petition To Promulgate Standards for Bears Under the Animal Welfare Act Regulations  

Federal Register 2010, 2011, 2012, 2013, 2014

...the public that the Animal and Plant Health Inspection...requesting that we amend the Animal Welfare Act regulations...species of bears held in captivity except polar bears...Ethical Treatment of Animals requesting that we initiate...species of bears held in captivity except polar...

2013-11-26

181

ANALYSIS AND TESTING OF A MAGNETIC BEARING ENERGY STORAGE FLYWHEEL WITH GAIN-SCHEDULED, MIMO CONTROL  

Microsoft Academic Search

The design and initial testing of a five axis magnetic bearing system in an energy storage flywheel is presented. The flywheel is under development at the University of Texas Center for Electromechanics (UT-CEM) for application in a transit bus. The bearing system for the prototype features homopolar permanent magnet bias magnetic bearings. The system has been successfully tested to the

Lawrence A. Hawkins; Brian T. Murphy; John Kajs

182

Partial tooth gear bearings  

NASA Technical Reports Server (NTRS)

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.

Vranish, John M. (Inventor)

2010-01-01

183

Radial Halbach Magnetic Bearings  

NASA Technical Reports Server (NTRS)

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

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

2009-01-01

184

Blood Pump Bearing System  

NASA Technical Reports Server (NTRS)

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.

Aber, Gregory S. (Inventor)

2000-01-01

185

Blood Pump Bearing System  

NASA Technical Reports Server (NTRS)

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.

Aber, Gregory S. (Inventor)

1999-01-01

186

Dinuclear silylium-enolate bifunctional active species: remarkable activity and stereoselectivity toward polymerization of methacrylate and renewable methylene butyrolactone monomers.  

PubMed

Novel dinuclear silylium-enolate active species, consisting of an electrophilic silylium catalyst site and a nucleophilic silicon enolate initiating site that are covalently linked as single molecules, and their unique polymerization characteristics and kinetics are reported. Such unimolecular, bifunctional propagating species are conveniently generated from activation of ethyl- and oxo-bridged disilicon enolate (i.e., disilyl ketene acetal, di-SKA) compounds with [Ph(3)C][B(C(6)F(5))(4)]. Both the ethyl- and oxo-bridged dinuclear species are much more active for the polymerization of methyl methacrylate (MMA) than the mononuclear SKA-based active species, exhibiting an approximate rate enhancement by a factor of 12 and 44, respectively. The oxo-bridged silylium-enolate species is considerably more active and controlled than the ethyl-bridged one, with their differences being even more pronounced in polymerizing a renewable monomer, ?-methyl-?-methylene-?-butyrolactone. The polymerization by the oxo-bridged silylium-enolate active species follows first-order kinetics in both monomer and silylium catalyst concentrations, indicating a unimolecular propagation mechanism which involves an intramolecular delivery of the polymeric enolate nucleophile to the monomer activated by the silylium ion electrophile being placed in proximity in the same catalyst molecule. Highly stereoregular poly(methyl methacrylate) (PMMA), with a syndiotacticity up to 92% rr, can be produced in quantitative yield using the oxo-bridged propagator at low temperature. PMID:21819049

Zhang, Yuetao; Gustafson, Laura O; Chen, Eugene Y-X

2011-08-31

187

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

PubMed

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

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

2014-05-01

188

Modular gear bearings  

NASA Technical Reports Server (NTRS)

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.

Vranish, John M. (Inventor)

2009-01-01

189

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

NASA Astrophysics Data System (ADS)

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

Tu, Chifeng; Yang, Yunhua; Gao, Mingyuan

2008-03-01

190

[Construction of a new bifunctional vector which contains EGFP-gene].  

PubMed

A number of bifunctional vector structures (pTpE, pTpE5, pTpH2, pTpH7, pTpS1) with molecular dimension of 11.3 kb has been created. Vector plasmids can be replicated, sustainably maintained and expressed both in Gram-negative (Escherichia coli XL1 Blue) and in Gram-positive (Streptomyces levoris 165) cultures. The given bifunctional vectors contain genes of resistance to 3 antibiotics. Genes of resistance to ampicillin and canamycin are expressed in E. coli cells, gene of resistance to thiostrepton ensures the resistance of streptomycete cells to the given antibiotic. It is proved that all the studied plasmids contain active egfp-gene which allows the visual study in vivo of the functioning of the poducts ofpEGFP-C1 gene cloned to polylinker. PMID:22686022

Luk'ianchuk, V V; Polishchuk, L V

2012-01-01

191

Amplified electrochemiluminescence detection of cancer cells using a new bifunctional quantum dot as signal probe.  

PubMed

In this work, we prepared a new electrochemiluminescent signal probe using a small bifunctional composite quantum dot (QD) with intense electrochemiluminescence (ECL) and excellent magnetic property, and developed a sensitive ECL biosensor for detection of cancer cells via DNA cyclic amplification technique. The graphene oxide (GO) with unique electrical properties was used as nano-amplified platform to immobilize a large number of capture DNA (c-DNA1). The endonuclease-assisted amplification technique was applied to amplify the ECL signal change induced by target cells. Specifically, the bifunctional composite QDs with excellent magnetic property can be conveniently labeled, separated, and developed the ECL signal probe, thus an ECL method for rapid and sensitive detection of cancer cells was developed. So far, it is for the first time that the small magnetic electrochemiluminescent QDs were applied to the assays of cancer cells by using amplification strategy, which is expected to have great potential for early clinical diagnosis of cancer. PMID:23891800

Jie, Guifen; Zhao, Yanbin; Niu, Shuyan

2013-12-15

192

Monte Carlo simulations of self-assembling hexagonal and cage-like bifunctional periodic mesoporous materials  

Microsoft Academic Search

Self-assembly of lyotropic liquid crystalline mesophases formed by amphiphilic molecules was studied using computer simulations. The addition of an inorganic and two hybrid organic-inorganic precursors, one with a bridging and the other with a terminal organic functionality, lead to the formation of bifunctional hexagonally-packed mesoporous materials. These structures exhibit very ordered and uniform mesopores with the organic functional groups located

Alessandro Patti; Allan D. Mackie; Flor R. Siperstein

2009-01-01

193

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

Microsoft Academic Search

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

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

2008-01-01

194

Dispersion polymerization of methyl methacrylate with a novel bifunctional polyurethane macromonomer as a reactive stabilizer  

Microsoft Academic Search

A novel macromonomer of vinyl-terminated bifunctional polyurethane was synthesized and applied to the dispersion polymerization of MMA in ethanol. The existence of the vinyl terminal groups and the grafted macromonomer with PMMA was verified using 1H NMR and 13C NMR. The stable and monodisperse PMMA microspheres having a weight-average diameter of 5.09 ?m and a good uniformity of 1.01 were

Sang Eun Shim; Hyejun Jung; Kangseok Lee; Jung Min Lee; Soonja Choe

2004-01-01

195

Direct synthesis of DME over bifunctional catalyst: surface properties and catalytic performance  

Microsoft Academic Search

A series of bifunctional catalysts CuO\\/ZnO\\/ZrO2\\/HZSM-5 with different ZrO2 contents were prepared and characterized by surface area, XRD and XPS analysis. The catalytic system was evaluated in the development of STD process (synthesis gas-to-dimethyl ether). Based on these results, it was deduced that the incorporation of ZrO2 in CuO lattice caused the formation of Cu+ on the catalyst surface during

Kunpeng Sun; Weiwei Lu; Fengyan Qiu; Shuwen Liu; Xianlun Xu

2003-01-01

196

Bifunctional anthracene derivatives as non-doped blue emitters and hole-transporters for electroluminescent devices.  

PubMed

New highly fluorescent bifunctional anthracenes showed high thermal and electrochemical stability, and great potential as both blue emitters and hole-transporters for OLEDs. Deep-blue and Alq3-based green devices with maximum efficiencies and CIE coordinates of 1.65 and 6.25 cd A(-1), and (0.15, 0.16) and (0.26, 0.49) were achieved, respectively. PMID:21614369

Thangthong, A-monrat; Meunmart, Duangratchaneekorn; Prachumrak, Narid; Jungsuttiwong, Siriporn; Keawin, Tinnagon; Sudyoadsuk, Taweesak; Promarak, Vinich

2011-07-01

197

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

SciTech Connect

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.

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

2011-06-15

198

Nitrogen-doped aligned carbon nanotube/graphene sandwiches: facile catalytic growth on bifunctional natural catalysts and their applications as scaffolds for high-rate lithium-sulfur batteries.  

PubMed

Nitrogen-doped aligned CNT/graphene sandwiches are rationally designed and in-situ fabricated by a facile catalytic growth on bifunctional natural catalysts that exhibit high-rate performances as scaffolds for lithium-sulfur batteries, with a high initial capacity of 1152 mA h g(-1) at 1.0 C. A remarkable capacity of 770 mA h g(-1) can be achieved at 5.0 C. Such a design strategy for materials opens up new perspectives to novel advanced functional composites, especially interface-modified hierarchical nanocarbons for broad applications. PMID:24862890

Tang, Cheng; Zhang, Qiang; Zhao, Meng-Qiang; Huang, Jia-Qi; Cheng, Xin-Bing; Tian, Gui-Li; Peng, Hong-Jie; Wei, Fei

2014-09-17

199

Lubricant effects on bearing life  

NASA Technical Reports Server (NTRS)

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.

Zaretsky, Erwin V.

1986-01-01

200

Gearbox Reliability Collaborative Bearing Calibration  

SciTech Connect

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.

van Dam, J.

2011-10-01

201

Bifunctional Electrophiles Cross-Link Thioredoxins with Redox Relay Partners in Cells  

PubMed Central

Thioredoxin protects cells against oxidative damage by reducing disulfide bonds in improperly oxidized proteins. Previously, we found that the baker's yeast cytosolic thioredoxin Trx2 undergoes cross-linking to form several protein-protein complexes in cells treated with the bifunctional electrophile divinyl sulfone (DVSF). Here, we report that the peroxiredoxin Tsa1 and the thioredoxin reductase Trr1, both of which function in a redox relay network with thioredoxin, become cross-linked in complexes with Trx2 upon DVSF treatment. Treatment of yeast with other bifunctional electrophiles, including diethyl acetylenedicarboxylate (DAD), mechlorethamine (HN2), and 1,2,3,4-diepoxybutane (DEB), resulted in the formation of similar cross-linked complexes. Cross-linking of Trx2 and Tsa1 to other proteins by DVSF and DAD is dependent on modification of the active site Cys residues within these proteins. In addition, the human cytosolic thioredoxin, cytosolic thioredoxin reductase, and peroxiredoxin 2 form cross-linked complexes to other proteins in the presence of DVSF, although each protein shows different susceptibilities to modification by DAD, HN2, and DEB. Taken together, our results indicate that bifunctional electrophiles potentially disrupt redox homeostasis in yeast and human cells by forming cross-linked complexes between thioredoxins and their redox partners. PMID:23414292

Naticchia, Matthew R.; Brown, Haley A.; Garcia, Francisco J.; Lamade, Andrew M.; Justice, Samantha L.; Herrin, Rachelle P.; Morano, Kevin A.; West, James D.

2013-01-01

202

(S)-5-(p-nitrobenzyl)-PCTA, a promising bifunctional ligand with advantageous metal ion complexation kinetics.  

PubMed

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(NO(2)-Bn-PCTA) (M = Mg(2+), Ca(2+), Cu(2+), Zn(2+)) complexes was similar to that of the corresponding PCTA complexes, while the stability of Ln(3+) complexes of the bifunctional ligand is somewhat lower than that of PCTA chelates. The rate of complex formation of Ln(NO(2)-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(NO(2)-Bn-PCTA) complexes showed that the kinetic inertness of the complexes was comparable to that of Ln(DOTA) chelates making the bifunctional ligand NO(2)-Bn-PCTA suitable for labeling biological vectors with radioisotopes for nuclear medicine applications. PMID:19220012

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

2009-03-18

203

Hybrid superconductor magnet bearings  

NASA Technical Reports Server (NTRS)

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.

Chu, Wei-Kan

1995-01-01

204

Bear vs Bee  

NSDL National Science Digital Library

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

2012-01-01

205

Hybrid superconductor magnet bearings  

SciTech Connect

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.

Chu, W.

1995-04-01

206

Tardigrada (Water Bears)  

NSDL National Science Digital Library

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

Micrographia

207

History of ball bearings  

NASA Technical Reports Server (NTRS)

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.

Dowson, D.; Hamrock, B. J.

1981-01-01

208

Oregon Zoo Polar Bear  

USGS Multimedia Gallery

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

209

Magnetically leviated superconducting bearing  

DOEpatents

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.

Weinberger, Bernard R. (Avon, CT); Lynds, Jr., Lahmer (Glastonbury, CT)

1993-01-01

210

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

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

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

211

Interference-Fit Life Factors for Roller Bearings  

NASA Technical Reports Server (NTRS)

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.

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

2009-01-01

212

Synthesis and comparative biological evaluation of bifunctional ligands for radiotherapy applications of (90)Y and (177)Lu.  

PubMed

Zevalin® is an antibody-drug conjugate radiolabeled with a cytotoxic radioisotope ((90)Y) that was approved for radioimmunotherapy (RIT) of B-cell non-Hodgkin's lymphoma. A bifunctional ligand that displays favorable complexation kinetics and in vivo stability is required for effective RIT. New bifunctional ligands 3p-C-DE4TA and 3p-C-NE3TA for potential use in RIT were efficiently prepared by the synthetic route based on regiospecific ring opening of aziridinium ions with prealkylated triaza- or tetraaza-backboned macrocycles. The new bifunctional ligands 3p-C-DE4TA and 3p-C-NE3TA along with the known bimodal ligands 3p-C-NETA and 3p-C-DEPA were comparatively evaluated for potential use in targeted radiotherapy using ?-emitting radionuclides (90)Y and (177)Lu. The bifunctional ligands were evaluated for radiolabeling kinetics with (90)Y and (177)Lu, and the corresponding (90)Y or (177)Lu-radiolabeled complexes were studied for in vitro stability in human serum and in vivo biodistribution in mice. The results of the comparative complexation kinetic and stability studies indicate that size of macrocyclic cavity, ligand denticity, and bimodality of donor groups have a substantial impact on complexation of the bifunctional ligands with the radiolanthanides. The new promising bifunctional chelates in the DE4TA and NE3TA series were rapid in binding (90)Y and (177)Lu, and the corresponding (90)Y- and (177)Lu-radiolabeled complexes remained inert in human serum or in mice. The in vitro and in vivo data show that 3p-C-DE4TA and 3p-C-NE3TA are promising bifunctional ligands for targeted radiotherapy applications of (90)Y and (177)Lu. PMID:25648683

Chong, Hyun-Soon; Sun, Xiang; Chen, Yunwei; Sin, Inseok; Kang, Chi Soo; Lewis, Michael R; Liu, Dijie; Ruthengael, Varyanna C; Zhong, Yongliang; Wu, Ningjie; Song, Hyun A

2015-03-01

213

Vygotsky and the Three Bears  

ERIC Educational Resources Information Center

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.

Kulczewski, Peggy

2004-01-01

214

Magnetic bearings grow more attractive  

SciTech Connect

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.

Not Available

1993-10-01

215

A self-lubricating bearing  

NASA Technical Reports Server (NTRS)

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

Whitaker, A. F. (inventor)

1974-01-01

216

Carbon Nanotube Linear Bearing Nanoswitches  

E-print Network

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

Bockrath, Marc

217

Frictionless Bearing Uses Permanent Magnets  

NASA Technical Reports Server (NTRS)

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.

1965-01-01

218

Plain bearing stresses due to forming and oil film pressure  

NASA Astrophysics Data System (ADS)

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.

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

2009-08-01

219

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

PubMed

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 Tra2? splicing factors, respectively. The C-to-T substitution concomitantly increases hnRNPA1 and weakens Tra2?-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

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

2015-05-01

220

Passive magnetic bearing system  

DOEpatents

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.

Post, Richard F.

2014-09-02

221

Centrifugally decoupling touchdown bearings  

DOEpatents

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.

Post, Richard F

2014-06-24

222

The Polar Bear Game  

NSDL National Science Digital Library

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

2010-10-24

223

Dicey Polar Bears  

NSDL National Science Digital Library

In this Sketchpad activity, which opens on Geometer's Sketchpad and on iOS with Sketchbook Explorer (cataloged separately), 5 dice are shown and the player must determine how many polar bears are around the ice holes. The participant tries to figure out the riddle (rules of the game) by studying the dice arrangements and the answers that correspond. In this game, players also determine the number of fish and plankton.

Meehank

2011-07-03

224

Bears in a Boat  

NSDL National Science Digital Library

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

2012-06-14

225

Night of the Bear  

NSDL National Science Digital Library

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

Casey Debenham

2002-08-25

226

Highly integrated magnetic bearings  

SciTech Connect

Active Magnetic Bearings (AMB) have many advantages, compared to other bearing concepts. However, for many potential applications they are still too complicated and too expensive. In this paper the authors will present a new concept for active magnetic bearings with smaller dimensions, lower power consumption, and lower cost. To achieve this goal the system has been optimized in an overall mechatronic design. This led to new concepts for rotor, magnets, electronics and control. A single chip computer is used to reduce the number of electronic components. The switches of the voltage controlled power amplifier are driven directly by the PWM-unit of the single chip computer. Additionally, also the frequency inverter for the motor is driven directly by the PWM-unit. This leads to a minimum number of electronic components including the emergency power supply provided through energy recovered by the inverter. For development, calibration and error diagnostics a powerful serial link to a PC has been implemented. It works at a speed of 57.6 kBit/s and realizes a direct interface to MATLAB. This new configuration has been successfully applied to a small rotor system spinning at 60,000 rpm.

Buehler, P.; Siegwart, R. [ETH-Center, Zurich (Switzerland); Herzog, R. [Mecos Traxler AG, Winterthur (Switzerland)

1995-12-31

227

Anti-backlash gear bearings  

NASA Technical Reports Server (NTRS)

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.

Vranish, John M. (Inventor)

2009-01-01

228

Bearing for liquid metal pump  

DOEpatents

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.

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

1984-01-01

229

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

E-print Network

profile using quantum chemical simulation methods. Monofunctional and bifunctional cisplatin adducts wereBifunctional Binding of Cisplatin to DNA: Why Does Cisplatin Form 1,2-Intrastrand Cross of the anticancer drug cisplatin to two adjacent nucleobases in DNA is modeled using density functional theory

Baik, Mu-Hyun

230

Effect of Bearing Cleaning on Long Term Bearing Life  

NASA Technical Reports Server (NTRS)

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.

Jett, Tim; Thom, R. L.

1999-01-01

231

Hybrid hydrostatic/ball bearings in high-speed turbomachinery  

NASA Technical Reports Server (NTRS)

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.

Nielson, C. E.

1983-01-01

232

Kalman Filter Behavior in Bearings-Only Tracking Applications  

Microsoft Academic Search

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

Vincent Aidala

1979-01-01

233

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

PubMed

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

Hailer, Frank

2015-03-01

234

Measurements of changes in the atmospheric partitioning of bifunctional carbonyls near a road in a suburban area  

NASA Astrophysics Data System (ADS)

Bifunctional carbonyls are ubiquitous in the atmosphere and are important contributors to atmospheric aerosols through heterogenous reactions. However, the actual contributions of bifunctional carbonyls to atmospheric aerosols have been little measured because of their capacity to coexist in both the gaseous phase and the particulate phase, making it difficult to sample them in both phases simultaneously. Using a short time resolution (2 h), we measured the atmospheric partitioning of semivolatile species to understand their contributions to atmospheric aerosols. Our results indicate that equilibrium between the gaseous phase and the particulate phase was due not only to thermodynamic partitioning but also to an aging process. Fresh emissions from motor vehicles affected the partitioning, and partitioning coefficients stabilized when the aerosols aged. The contribution of bifunctional carbonyl compounds to atmospheric aerosols was 3-8 orders of magnitude higher than that estimated by thermodynamic predictions, corroborating previous findings.

Ortiz, R.; Shimada, S.; Sekiguchi, K.; Wang, Q.; Sakamoto, K.

2013-12-01

235

H6phospa-Trastuzumab: Bifunctional Methylenephosphonate-based Chelator with 89Zr, 111In and 177Lu  

PubMed Central

The acyclic chelator H6phospa and the bifunctional derivative p-SCN-Bn-H6phospa have been synthesized using nosyl protection chemistry and evaluated with 89Zr, 111In, and 177Lu. The p-SCN-Bn-H6phospa derivative was successfully conjugated to trastuzumab with isotopic dilution assays indicating 3.3 ± 0.1 chelates per antibody and in vitro cellular binding assays indicating an immunoreactivity value of 97.9 ± 2.6%. Radiolabeling of the H6phospa-trastuzumab immunoconjugate was achieved with 111In in 70–90% yields at room temperature in 30 minutes, while 177Lu under the same conditions produced more inconsistent yields of 40–80%. Stability experiments in human serum revealed the 111In-phospa-trastuzumab complex to be 52.0 ± 5.3% intact after 5 days at 37 °C, while the 177Lu-phospa-trastuzumab to be only 2.0 ± 0.3% intact. Small animal SPECT/CT imaging using mice bearing subcutaneous SKOV-3 ovarian cancer xenografts was performed, and it was found that 111In-phospa-trastuzumab successfully identified and delineated small (~2 mm in diameter) tumors from surrounding tissues, despite visible uptake in the kidneys and bone due to moderate chelate instability. As predicted from stability assays in serum, the 177Lu-phospa-trastuzumab conjugate served as a negative control and displayed no tumor uptake, with high uptake in bones indicating rapid and complete radiometal dissociation and suggesting a potential application of H6phospa in transient lanthanide chelation for bone-delivery. Radiolabeling with 89Zr was attempted, but even with elevated temperatures of 37 °C, the maximum observed radiometal incorporation over 18 hours was 12%. It can be concluded from this work that H6phospa is not superior to the previously studied H4octapa for use with 111In and 177Lu, but improvements in 89Zr radiolabeling were observed over H4octapa, suggesting H6phospa to be an excellent starting point for elaboration of 89Zr-based radiopharmaceutical development. To our knowledge, H6phospa is the best desferrioxamine alternative for 89Zr radiolabeling to be studied to date. PMID:24104523

Price, Eric W.; Zeglis, Brian M.

2013-01-01

236

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

NASA Astrophysics Data System (ADS)

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.

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

2005-11-01

237

Fretting fatigue mechanism of bearing cap bolted joints  

NASA Astrophysics Data System (ADS)

Fretting fatigue is a common type of failure of the bearing cap bolted joints. This paper proposes a methodology to analyze the fretting fatigue mechanism of the bearing cap bolted joint. A biaxially loading system was designed to simulate fretting fatigue failure under typical engine working condition. Meanwhile, a submodel was developed in the finite element calculation to analyze the contact status and stress distribution of the structural models. The test result shows that long inclined cracks (about 650 ?m long, orientation at 17°-34°) initiate at the middle region of the contact interface. As the increase of the bolt pretension load (from 6000 N to 10 000 N), the crack initial location is getting away from the bolt screw, and the fretting fatigue lives is increasing (from 7.8 × 105 to 6.0 × 106). With the fatigue phenomenon and the stress field analysis result, it concludes that the crack initiation is governed by the maximum shear stress; the bolt pretension load and the additional rotate torque caused by the bearing load are the two main factors which affect the fretting fatigue mechanism of the bearing cap bolted joints. It is beneficial to fretting fatigue lives of the bearing cap joints by increasing the bolt pretension load and restraining the oscillation of the bearing cap.

Li, Xin; Zuo, Zhengxing; Qin, Wenjie

2014-05-01

238

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

PubMed

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

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

239

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

PubMed

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

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

2015-03-01

240

Dialogue for Kids Wild About Bears Sleepy Bear Lesson Plan  

NSDL National Science Digital Library

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

241

Aerospace applications of magnetic bearings  

NASA Technical Reports Server (NTRS)

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.

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

1994-01-01

242

PNA bearing 5-azidomethyluracil  

PubMed Central

Fmoc- and Boc-protected modified monomers bearing 5-azidomethyluracil nucleobase were synthesized. Four different solid-phase synthetic strategies were tested in order to evaluate the application of this series of monomers for the solid-phase synthesis of modified PNA. The azide was used as masked amine for the introduction of amide-linked functional groups, allowing the production of a library of compounds starting from a single modified monomer. The azide function was also exploited as reactive group for the modification of PNA in solution via azide-alkyne click cycloaddition. PMID:22772040

Manicardi, Alex; Accetta, Alessandro; Tedeschi, Tullia; Sforza, Stefano; Marchelli, Rosangela; Corradini, Roberto

2012-01-01

243

Actively controlled superconducting bearings  

NASA Astrophysics Data System (ADS)

Actively controlled conventional radial beating using copper winding and soft magnetic material can provide only up to 200 N/sq cm of pressure. Large cryogenic pumps for space applications operating at 30,000 rpm and high rpm machines may require larger magnetic pressure. We show that using superconducting winding in the rotor and the stator of a magnetic bearing system increases the pressure by an order of magnitude. The paper addresses winding configuration, stability, ac losses, and power requirement for the superconducting winding.

Eyssa, Yehia M.; Huang, X.

244

Basic evaluation of 67Ga labeled digoxin derivative as a metal-labeled bifunctional radiopharmaceutical.  

PubMed

To develop metal-labeled digoxin radiopharmaceuticals with affinity with anti-digoxin antibody as well as Na+,K(+)-ATPase, a digoxin derivative conjugated with deferoxamine was synthesized. The derivative had a high binding affinity with 67Ga at deferoxamine introduced to the terminal sugar ring of digoxin. The 67Ga labeled digoxin derivative showed enough in vitro binding affinity and selectivity to anti-digoxin antibody as well as Na+,K(+)-ATPase. The 67Ga labeled digoxin derivative is considered to be a potential metal-labeled bifunctional radiopharmaceutical for digoxin RIA as well as myocardial Na+,K(+)-ATPase imaging. PMID:8292449

Fujibayashi, Y; Takemura, Y; Taniuchi, H; Iijima, N; Konishi, J; Yokoyama, A

1993-11-01

245

Characterization of a Bifunctional Cytidine 5?Monophosphate N -acetylneuraminic acid Synthetase Cloned from Streptococcus Agalactiae  

Microsoft Academic Search

Recombinant CMP-sialic acid synthetase, cloned from Streptococcus agalactiae serotype V strain 2603 V\\/R, is bifunctional having both CMP-sialic acid synthetase and acetylhydrolase (acylesterase) activities.\\u000a The enzyme is active over a wide pH range with an optimal CMP-sialic acid synthetase activity at pH 9.0 and an optimal acetylhydrolase\\u000a activity at pH 8.0. A metal cofactor (either Mg2+ or Mn2+) is required

Hui Yu; Wesley Ryan; Hai Yu; Xi Chen

2006-01-01

246

A bi-functional block copolymer hydrogels for protein and drug delivery  

Microsoft Academic Search

Novel biodegradable & injectable poly(?-amino ester)-poly(?-caprolactone)- poly(ethylene glycol)-poly(?-caprolactone)-poly(?-amino ester)(PAE-PCL-PEG-PCL- PAE) bi-functional, pH\\/temperature-sensitive, block copolymer hydrogels were prepared and applied to protein and drug delivery. In this study, human insulin(HI) was loaded into this copolymer as a model protein and the release of HI was investigated in vitro and in vivo. In in vivo experiments, the polymer solution including the complex

Doo Sung Lee

2007-01-01

247

Creation through immobilization: a new family of high performance heterogeneous bifunctional iminophosphorane (BIMP) superbase organocatalysts.  

PubMed

An immobilized chiral bifunctional iminophosphorane superbase organocatalyst has been developed and applied in a range of challenging enantioselective reactions. A unique feature of this novel catalytic system is that the final step creation of the iminophosphorane occurs at the point of immobilization. The utility of the immobilized catalyst system was demonstrated in the nitro-Mannich reaction of ketimines as well as the conjugate addition of high pKa 1,3-dicarbonyl pro-nucleophiles to nitrostyrene. Catalyst recycling was also demonstrated. PMID:25459386

Goldys, Anna M; Núñez, Marta G; Dixon, Darren J

2014-12-19

248

Bifunctional Iminophosphorane Organocatalysts for Enantioselective Synthesis: Application to the Ketimine Nitro-Mannich Reaction  

PubMed Central

The design, synthesis, and development of a new class of modular, strongly basic, and tunable bifunctional Brønsted base/H-bond-donor organocatalysts are reported. These catalysts incorporate a triaryliminophosphorane as the Brønsted basic moiety and are readily synthesized via a last step Staudinger reaction of a chiral organoazide and a triarylphosphine. Their application to the first general enantioselective organocatalytic nitro-Mannich reaction of nitromethane to unactivated ketone-derived imines allows the enantioselective construction of ?-nitroamines possessing a fully substituted carbon atom. The reaction is amenable to multigram scale-up, and the products are useful for the synthesis of enantiopure 1,2-diamine and ?-amino acid derivatives. PMID:24107070

2013-01-01

249

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

SciTech Connect

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.

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

2014-12-01

250

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

NASA Astrophysics Data System (ADS)

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

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

2014-11-01

251

Effect of Bearing Cleaning on Long Term Bearing Life  

NASA Technical Reports Server (NTRS)

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.

Jett, Timothy Raymond; Thom, Robert L.

1998-01-01

252

Toxic Chemicals Initiative  

NSDL National Science Digital Library

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

253

Downhole bearing assembly  

SciTech Connect

A sealed downhole bearing assembly is described which consists of: an outer tube adapted to be connected to a first portion of a drill string; an inner tube adapted to be connected to a second portion of a drill string and disposed within the outer tube to define an enclosed annular space therebetween; at least one bearing mounted in the annular space between the outer and inner tubes to allow relative rotation therebetween; at least one high pressure seal mounted in the annular space between the outer and inner tubes to divide the annular space into first and second chambers; first and second abrasion resistant, metal-to-metal seals mounted between the inner and outer tubes to seal the first and second chambers, respectively, the first seal in fluid communication with an outer region exterior of the outer tube and the second seal in fluid communication with an inner region interior of the inner tube, the metal-to-metal seals adapted to seal effectively when in contact with drilling mud; first and second pressure balancing systems in communication with the first and second chambers, respectively, the first pressure balancing system also in communication with the outer region to balance pressure in the first chamber with respect to the outer region, the second pressure balancing system also in communication with the inner region to balance pressure in the second chamber with respect to the inner region; each of the pressure balancing systems comprising respective flexible, variable volume containers.

Lingafelter, J.

1986-06-10

254

Liquid hydrogen turbopump foil bearing  

NASA Technical Reports Server (NTRS)

Space transfer vehicles and other power and propulsion systems require long-life turbopumps. Rolling element bearings used in current turbopumps do not have sufficient life for these applications. Process fluid foil bearings have established long life, with exceptional reliability, over a wide range of temperatures and fluids in many high-speed turbomachinery applications. However, liquid hydrogen turbopumps require high-load capacity bearings. An experimental study was conducted to measure foil journal bearing load capacity in liquid hydrogen, using a bearing designed specifically for cryogenic hydrogen turbopump applications. Additional performance parameters such as power loss, stability, cooling flow requirements, and bearing life were measured. These tests showed a load capacity safety factor of approximately 10 for liquid hydrogen turbopump applictions. These tests also demonstrated good rotor stability, low power loss and cooling flow, and long life.

Saville, M.; Gu, A.; Capaldi, R.

1991-01-01

255

Ecological effects of contaminants and remedial actions in Bear Creek  

SciTech Connect

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.

Southworth, G.R.; Loar, J.M.; Ryon, M.G.; Smith, J.G.; Stewart, A.J. (Oak Ridge National Lab., TN (United States)); Burris, J.A. (C. E. Environmental, Inc., Tallahassee, FL (United States))

1992-01-01

256

Primarily Pro-bear-bility  

NSDL National Science Digital Library

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

2006-01-01

257

Robust and intelligent bearing estimation  

DOEpatents

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

Claassen, John P. (Albuquerque, NM)

2000-01-01

258

76 FR 57019 - Ball Bearings and Parts Thereof From France, Germany and Italy: Final Results of Sunset Reviews...  

Federal Register 2010, 2011, 2012, 2013, 2014

...Bearings and Parts Thereof From France, Germany and Italy: Final Results of Sunset Reviews...bearings and parts thereof from France, Germany, and Italy. See Initiation of Five-Year...bearings and parts thereof from France, Germany, and Italy. DATES: Effective...

2011-09-15

259

Spin bearing retainer design optimization  

NASA Technical Reports Server (NTRS)

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.

Boesiger, Edward A.; Warner, Mark H.

1991-01-01

260

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

SciTech Connect

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.

Hine, J.; Sinha, A.

1984-06-15

261

Ambient air measurements of six bifunctional carbonyls in a suburban area  

NASA Astrophysics Data System (ADS)

Low-molecular-weight carbonyl compounds, generated by photochemical reactions in the atmosphere and found in the exhaust of motor vehicles, have recently come to the attention of researchers because some of them are suspected carcinogens or mutagens. Six bifunctional carbonyl compounds were detected and measured in a suburban site 30 km northwest of the Tokyo metropolitan area. Samples were taken on five sunny days between 2 August and 11 August 2003 with a low-volume denuder and three-filter tandem system using O-(2,3,4,5,6-pentafluorobenzyl)hydroxylamine (PFBHA) as a sorbent. Bifunctional carbonyls were measured by gas chromatography-mass spectrometry after two derivatization processes with PFBHA and N, O-bis(trimethylsilyl)-trifluoroacetamide (BSTFA). The average total (gas plus particle) concentrations were 162.8 ng m - 3 for pyruvic acid, 113.7 ng m - 3 for methylglyoxal, 36.0 ng m - 3 for glycolaldehyde and 58.6 ng m - 3 for glyoxal.

Ortiz, Ricardo; Hagino, Hiroyuki; Sekiguchi, Kazuhiko; Wang, Qingyue; Sakamoto, Kazuhiko

2006-12-01

262

Dispersion polymerization of methyl methacrylate with a novel bifunctional polyurethane macromonomer as a reactive stabilizer.  

PubMed

A novel macromonomer of vinyl-terminated bifunctional polyurethane was synthesized and applied to the dispersion polymerization of MMA in ethanol. The existence of the vinyl terminal groups and the grafted macromonomer with PMMA was verified using 1H NMR and 13C NMR. The stable and monodisperse PMMA microspheres having a weight-average diameter of 5.09 microm and a good uniformity of 1.01 were obtained with 20 wt% polyurethane macromonomer. The molecular weight increased, but the size of the synthesized PMMA microspheres decreased with the macromonomer concentration since the macromonomer acts as a reactive stabilizer in dispersion polymerization. Furthermore, the molecular weight of the PMMA prepared by the use of the macromonomer was approximately twofold higher than that prepared by a conventional stabilizer, poly(N-vinylpyrrolidone). The higher molecular weight is thought to originate from the grafting and a possibly slight crosslinking of PMMA molecules due to the bifunctional reactive groups at the ends of macromonomer chains. PMID:15464812

Shim, Sang Eun; Jung, Hyejun; Lee, Kangseok; Lee, Jung Min; Choe, Soonja

2004-11-15

263

Facile synthesis of folate-conjugated magnetic/fluorescent bifunctional microspheres  

PubMed Central

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

2014-01-01

264

Proteolytic and partial sequencing studies of the bifunctional dihydrofolate reductase-thymidylate synthase from Daucus carota.  

PubMed

The bifunctional dihydrofolate reductase-thymidylate synthase (DHFR-TS) of Daucus carota has been further characterized as regards molecular weight, amino acid composition, protease digestion and microsequencing of proteolytic peptides. Data reported in this paper demonstrate that the carrot protein has a calculated Mr of 124,000 thus indicating that, contrarily to what has previously been suggested, it occurs as a dimer of identical subunits. Results of partial amino acid microsequencing show the presence of sequences highly homologous with those of the active sites of both DHFR and TS from other organisms confirming, at the structural level, the bifunctional nature of the carrot protein. As in the case of Leishmania tropica DHFR-TS, incubation of the carrot protein with V8 protease led to a rapid loss of TS activity while retaining that of DHFR. However the pattern of proteolysis did not allow to establish whether the sequence of domains is DHFR-TS as in Leishmania, or vice versa. Low homology of other amino acid sequences, as judged by computer analysis, and absence of common epitopes indicate an apparent divergence between carrot and leishmanian proteins. PMID:1863769

Cella, R; Carbonera, D; Orsi, R; Ferri, G; Iadarola, P

1991-06-01

265

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

PubMed Central

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

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

2012-01-01

266

Pushing the theoretical limit of Li-CF(x) batteries: a tale of bifunctional electrolyte.  

PubMed

In a typical battery, the inert electrolyte functions solely as the ionic conductor without contribution to the cell capacity. Here we demonstrate that the most energy-dense Li-CF(x) battery delivers a capacity exceeding the theoretical maximum of CF(x) 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 bifunctional electrolyte reconciles both inert and active characteristics through a synergistic discharge mechanism of CF(x) and LPS. The synergy at the cathode is through LiF, the discharge product of CF(x), which activates the electrochemical discharge of LPS at a close electrochemical potential of CF(x). Therefore, the solid-state Li-CF(x) batteries output 126.6% energy beyond their theoretic limits without compromising the stability of the cell voltage. The additional energy comes from the electrochemical discharge of LPS, the inert electrolyte. This bifunctional electrolyte revolutionizes the concept of conventional batteries and opens a new avenue for the design of batteries with unprecedented energy density. PMID:24730570

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

2014-05-14

267

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

SciTech Connect

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.

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

2014-01-01

268

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

PubMed

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

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

2011-11-01

269

The Bifunctional Pyruvate Decarboxylase/Pyruvate Ferredoxin Oxidoreductase from Thermococcus guaymasensis  

PubMed Central

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

2014-01-01

270

Rational Design and Generation of a Bimodal Bifunctional Ligand for Antibody-Targeted Radiation Cancer Therapy  

PubMed Central

An antibody-targeted radiation therapy (radioimmunotherapy, RIT) employs a bifunctional ligand that can effectively hold a cytotoxic metal with clinically acceptable complexation kinetics and stability while being attached to a tumor-specific antibody. Clinical exploration of the therapeutic potential of RIT has been challenged by the absence of adequate ligand, a critical component for enhancing the efficacy of the cancer therapy. To address this deficiency, the bifunctional ligand C-NETA in a unique structural class possessing both a macrocyclic cavity and a flexible acyclic moiety was designed. The practical, reproducible, and readily scalable synthetic route to C-NETA was developed, and its potential as the chelator of 212Bi, 213Bi, and 177Lu for RIT was evaluated in vitro and in vivo. C-NETA rapidly binds both Lu(III) and Bi(III), and the respective metal complexes remain extremely stable in serum for 14 days. 177Lu—C-NETA and 205/6Bi—C-NETA possess an excellent or acceptable in vivo biodistribution profile. PMID:18062661

Chong, Hyun-Soon; Ma, Xiang; Le, Thien; Kwamena, Baidoo; Milenic, Diane E.; Brady, Erik D.; Song, Hyun A.; Brechbiel, Martin W.

2008-01-01

271

Bifunctional metal-free catalysis of mesoporous noble carbons for oxygen reduction and evolution reactions.  

PubMed

Electrochemical oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) are key reactions in lithium-oxygen batteries (LOBs) being a promising candidate to store renewable energies due to their high specific energy. However current development on LOBs is suffering from unsuitable catalysts. In particular, carbon-based catalysts were found to perform poorly in this system. Here, we show that metal-free mesoporous nitrogen-doped carbons (meso-NdCs) offer highly promising performances in both ORR and OER; they act as bifunctional catalysts, and can be synthesized by a very simple method. The efficient electrocatalytic activity of ORR and OER was used in a LOB cell during discharge and charge, respectively, and the present system showed a lower overpotential comparable to metal-based catalysts in LOB system. Thus, we demonstrate that meso-NdCs act as a new and affordable candidate for the efficient bifunctional oxygen catalysis, therefore can be applied to many energy-related applications. PMID:25739370

Sakaushi, Ken; Fellinger, Tim-Patrick; Antonietti, Markus

2015-04-13

272

Evaluation of K(HYNIC)2 as A Bifunctional Chelator for 99mTc-Labeling of Small Biomolecules  

PubMed Central

This study sought to evaluate K(HYNIC)2 (K = lysine and HYNIC = 6-hydrazinonicotinyl) as a bifunctional chelator for 99mTc-labeling of biomolecule. In this study, four K(HYNIC)2–conjugated cyclic RGD peptides, K(HYNIC)2-RGD2 (RGD2 = E[c(RGDfK)]2), K(HYNIC)2-3G-RGD2 (3G-RGD2 = Gly-Gly-Gly-E[Gly-Gly-Gly-c(RGDfK)]2), K(HYNIC)2-2P-RGD2 (2P-RGD2 = E[PEG4-c(RGDfK)]2, and PEG4 = 15-amino-4,7,10,13-tetraoxapentadecanoic acid), and K(HYNIC)2-3P-RGD2 (3P-RGD2 = PEG4-E[PEG4-c(RGDfK)]2) were prepared, and evaluated for their integrin ?v?3 binding affinity. IC50 values were determined to be 47 ± 2, 35 ± 2, 37 ± 2, 85 ± 2 and 422 ± 15 nM for K(HYNIC)2-2P-RGD2, K(HYNIC)2-3P-RGD2, K(HYNIC)2-3G-RGD2, K(HYNIC)2-RGD2 and c(RGDyK), respectively, against 125I-echistatin bound to U87MG cells. Macrocyclic complexes [99mTc(K(HYNIC)2-RGD2)(tricine)] (1), [99mTc(K(HYNIC)2-3G-RGD2)(tricine)] (2), [99mTc(K(HYNIC)2-2P-RGD2)(tricine)] (3), and [99mTc(K(HYNIC)2-3P-RGD2)(tricine)] (4) were prepared, and evaluated in athymic nude mice bearing U87MG glioma xenografts for their tumor targeting capability and biodistribution. It was found that 1 – 4 all had high solution stability and more than two isomers, as evidenced by the presence of multiple radiometric peaks in their radio-HPLC chromatograms. The tumor uptake of 1 – 4 was 3.78 ± 0.81, 7.46 ± 1.68, 9.74 ± 1.65 and 8.59 ± 1.52 %ID/g, respectively, which was completely consistent with trend of integrin ?v?3 binding affinity for cyclic RGD peptides. Replacing [99mTc(HYNIC)(tricine)(TPPTS)] (TPPTS = trisodium triphenylphosphine-3,3?,3?-trisulfonate) with [99mTc(K(HYNIC)2)(tricine)] had little impact on radiotracer tumor uptake; but it had significant effect on the uptake of radiotracer in kidneys, lungs and spleen. The tumor was clearly visualized by SPECT/CT with excellent contrast in a glioma-bearing mouse administered with 4. K(HYNIC)2 would be particularly useful for 99mTc-labeling of small biomolecules with one or more disulfide linkages. PMID:23521129

Ji, Shundong; Zhou, Yang; Shao, Guoqiang; Liu, Shuang

2013-01-01

273

Bifunctional staining for ex vivo determination of area at risk in rabbits with reperfused myocardial infarction  

PubMed Central

AIM: To develop a method for studying myocardial area at risk (AAR) in ischemic heart disease in correlation with cardiac magnetic resonance imaging (cMRI). METHODS: Nine rabbits were anesthetized, intubated and subjected to occlusion and reperfusion of the left circumflex coronary artery (LCx) to induce myocardial infarction (MI). ECG-triggered cMRI with delayed enhancement was performed at 3.0 T. After euthanasia, the heart was excised with the LCx re-ligated. Bifunctional staining was performed by perfusing the aorta with a homemade red-iodized-oil (RIO) dye. The heart was then agar-embedded for ex vivo magnetic resonance imaging and sliced into 3 mm-sections. The AAR was defined by RIO-staining and digital radiography (DR). The perfusion density rate (PDR) was derived from DR for the AAR and normal myocardium. The MI was measured by in vivo delayed enhancement (iDE) and ex vivo delayed enhancement (eDE) cMRI. The AAR and MI were compared to validate the bifunctional straining for cardiac imaging research. Linear regression with Bland-Altman agreement, one way-ANOVA with Bonferroni’s multiple comparison, and paired t tests were applied for statistics. RESULTS: All rabbits tolerated well the surgical procedure and subsequent cMRI sessions. The open-chest occlusion and close-chest reperfusion of the LCx, double suture method and bifunctional staining were successfully applied in all animals. The percentage MI volumes globally (n = 6) and by slice (n = 25) were 36.59% ± 13.68% and 32.88% ± 12.38% on iDE, and 35.41% ± 12.25% and 32.40% ± 12.34% on eDE. There were no significant differences for MI determination with excellent linear regression correspondence (rglobal = 0.89; rslice = 0.9) between iDE and eDE. The percentage AAR volumes globally (n = 6) and by slice (n = 25) were 44.82% ± 15.18% and 40.04% ± 13.64% with RIO-staining, and 44.74% ± 15.98% and 40.48% ± 13.26% by DR showing high correlation in linear regression analysis (rglobal = 0.99; rslice = 1.0). The mean differences of the two AAR measurements on Bland-Altman were almost zero, indicating RIO-staining and DR were essentially equivalent or inter-replaceable. The AAR was significantly larger than MI both globally and slice-by-slice (P < 0.01). After correction with the background and the blank heart without bifunctional staining (n = 3), the PDR for the AAR and normal myocardium was 32% ± 15% and 35.5% ± 35%, respectively, which is significantly different (P < 0.001), suggesting that blood perfusion to the AAR probably by collateral circulation was only less than 10% of that in the normal myocardium. CONCLUSION: The myocardial area at risk in ischemic heart disease could be accurately determined postmortem by this novel bifunctional staining, which may substantially contribute to translational cardiac imaging research. PMID:25237621

Feng, Yuanbo; Ma, Zhan-Long; Chen, Feng; Yu, Jie; Cona, Marlein Miranda; Xie, Yi; Li, Yue; Ni, Yicheng

2013-01-01

274

The polar bear phenomena  

SciTech Connect

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.

Maw, P.K. (United Kingdom Ingersoll-Rand Sales Company, Ltd., Horwich, Bolton Lancashire, BL6 6JN (GB)); Lane, M.T.

1990-02-01

275

Superconducting levitating bearing  

NASA Technical Reports Server (NTRS)

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.

Moon, Francis C. (Inventor)

1996-01-01

276

Introduction to magnetic bearings  

NASA Technical Reports Server (NTRS)

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.

Skowronski, Lori; Bisese, Anne

1993-01-01

277

Synthesis and characterization of bifunctional hybrid nanocomposite YPO4:5Eu@Fe3O4  

NASA Astrophysics Data System (ADS)

Spherical, non-agglomerated and highly water dispersed bifunctional YPO4:5Eu@Fe3O4 nanocomposite was prepared by coprecipitation method. The nanohybrid shows characteristic induction heating under AC magnetic field by reaching the hyperthermia temperature (˜42°C) and giving red emission under 395nm excitation, characteristic of Eu3+, thus potential material for biological applications.

Prasad, Amresh I.; Singh, L. Robindro; Parchur, A. K.; Ninghthoujam, R. S.

2014-04-01

278

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

PubMed

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

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

2014-12-21

279

Bifunctional thiourea-catalyzed enantioselective double Michael reaction of ?,?-unsaturated ?-ketoester to nitroalkene: asymmetric synthesis of (?)-epibatidine  

Microsoft Academic Search

The asymmetric synthesis of 4-nitrocyclohexanone derivatives has been accomplished by enantioselective double Michael additions of ?,?-unsaturated ?-ketoesters to nitroalkenes using a catalytic amount of bifunctional thiourea and TMG. The three contiguous stereogenic centers of the obtained products were constructed with good to high diastereoselectivity and up to 92% ee. The biologically active natural product, (?)-epibatidine, has been synthesized from the

Yasutaka Hoashi; Takaya Yabuta; Yoshiji Takemoto

2004-01-01

280

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

E-print Network

5790 J. Am. Chem. SOC.1987, 109, 5790-5800 Concerted General Base and Bifunctional General Acid. It is concluded that the reaction involves concerted general base catalysis of prQton abstraction from pyrazole addition species,p,to reactants suggests that the concerted mechanism is enforced by the absence

Cox, Michael M.

281

Structure of Human Epoxide Hydrolase Reveals Mechanistic Inferences on Bifunctional Catalysis in Epoxide and Phosphate Ester Hydrolysis,  

E-print Network

Structure of Human Epoxide Hydrolase Reveals Mechanistic Inferences on Bifunctional Catalysis ReceiVed February 4, 2004 ABSTRACT: The X-ray crystal structure of human soluble epoxide hydrolase (s mechanism of the human enzyme proceeds through an alkyl-enzyme intermediate with Asp-333 in the C

Hammock, Bruce D.

282

Permanent-Magnet Meissner Bearing  

NASA Technical Reports Server (NTRS)

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.

Robertson, Glen A.

1994-01-01

283

Spherical-Bearing Analysis Program  

NASA Technical Reports Server (NTRS)

Computer program SPHERBEAN, developed to predict thermomechanical performance characteristics of double-row spherical roller bearings over wide range of operating conditions. Analysis allows six degrees of freedom for each roller and three for each half of an optionally split cage. Program capabilities provide sufficient generality to allow detailed simulation of both high-speed and conventional bearing operation.

Kleckner, R. J.

1984-01-01

284

Polar Bears and Climate Change  

NSDL National Science Digital Library

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

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

2008-05-01

285

Nonlinear control of magnetic bearings  

NASA Technical Reports Server (NTRS)

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.

Pradeep, A. K.; Gurumoorthy, R.

1994-01-01

286

Immobilization of Wyoming bears using carfentanil and xylazine.  

PubMed

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

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

2013-07-01

287

Oxygen electrode bifunctional electrocatalyst NiCo2O4 spinel  

NASA Technical Reports Server (NTRS)

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.

Fielder, William L.; Singer, Joseph

1988-01-01

288

Bears, Big and Little. Young Discovery Library Series.  

ERIC Educational Resources Information Center

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)…

Pfeffer, Pierre

289

36 CFR 13.1236 - Bear orientation.  

Code of Federal Regulations, 2012 CFR

... 2012-07-01 false Bear orientation. 13.1236 Section 13.1236...Developed Area § 13.1236 Bear orientation. All persons visiting the BCDA must receive an NPS-approved Bear Orientation. Failure to receive an...

2012-07-01

290

36 CFR 13.1236 - Bear orientation.  

Code of Federal Regulations, 2013 CFR

... 2013-07-01 false Bear orientation. 13.1236 Section 13.1236...Developed Area § 13.1236 Bear orientation. All persons visiting the BCDA must receive an NPS-approved Bear Orientation. Failure to receive an...

2013-07-01

291

36 CFR 13.1236 - Bear orientation.  

Code of Federal Regulations, 2011 CFR

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

2011-07-01

292

36 CFR 13.1236 - Bear orientation.  

Code of Federal Regulations, 2010 CFR

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

2010-07-01

293

36 CFR 13.1236 - Bear orientation.  

Code of Federal Regulations, 2014 CFR

... 2014-07-01 false Bear orientation. 13.1236 Section 13.1236...Developed Area § 13.1236 Bear orientation. All persons visiting the BCDA must receive an NPS-approved Bear Orientation. Failure to receive an...

2014-07-01

294

USGS Scientist Taking Measurements Along Bear Creek  

USGS Multimedia Gallery

USGS Scientist Taking Measurements Along Bear Creek - Photo taken by Heidi Koontz, USGS Communications, Friday, Sept. 13. USGS scientist Ben Glass conducting current profiler measurements along Bear Creek near Bear Creek Lake in Morrison, Colo....

295

49 CFR 229.64 - Plain bearings.  

Code of Federal Regulations, 2013 CFR

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

2013-10-01

296

49 CFR 229.64 - Plain bearings.  

Code of Federal Regulations, 2014 CFR

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

2014-10-01

297

49 CFR 229.64 - Plain bearings.  

Code of Federal Regulations, 2010 CFR

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

2010-10-01

298

49 CFR 229.64 - Plain bearings.  

Code of Federal Regulations, 2011 CFR

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

2011-10-01

299

49 CFR 229.64 - Plain bearings.  

Code of Federal Regulations, 2012 CFR

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

2012-10-01

300

49 CFR 229.69 - Side bearings.  

Code of Federal Regulations, 2011 CFR

...2011-10-01 2011-10-01 false Side bearings. 229.69 Section 229.69 Transportation...Requirements Suspension System § 229.69 Side bearings. (a) Friction side bearings with springs designed to carry weight...

2011-10-01

301

49 CFR 229.69 - Side bearings.  

Code of Federal Regulations, 2013 CFR

...2013-10-01 2013-10-01 false Side bearings. 229.69 Section 229.69 Transportation...Requirements Suspension System § 229.69 Side bearings. (a) Friction side bearings with springs designed to carry weight...

2013-10-01

302

Magnetic Bearings at Draper Laboratory  

NASA Technical Reports Server (NTRS)

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.

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

1996-01-01

303

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

PubMed Central

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

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

2013-01-01

304

Random bearings and their stability.  

PubMed

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

Mahmoodi Baram, Reza; Herrmann, Hans J

2005-11-25

305

Using a Bear Put Spread  

E-print Network

might be used when the marketer is bearish on a market to a point (i.e., the marketer believes the market has limited downside risk). An attractive feature of the bear put spread is that once the strike prices are selected and the premiums are known..., the maximum loss and net potential gain from the spread are also known. When to Use a Bear Put Spread A producer can use a bear put spread to hedge against a falling market. However, if the market falls below the strike price of the sold put op- tion...

Bevers, Stan; Amosson, Stephen H.; Waller, Mark L.; Dhuyvetter, Kevin C.

2008-10-07

306

Analysis of foil bearings for high speed operation in cryogenic applications  

NASA Technical Reports Server (NTRS)

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

Carpino, Marc

1991-01-01

307

Quantification of noise in bifunctionality-induced post-translational modification  

NASA Astrophysics Data System (ADS)

We present a generic analytical scheme for the quantification of fluctuations due to bifunctionality-induced signal transduction within the members of a bacterial two-component system. The proposed model takes into account post-translational modifications in terms of elementary phosphotransfer kinetics. Sources of fluctuations due to autophosphorylation, kinase, and phosphatase activity of the sensor kinase have been considered in the model via Langevin equations, which are then solved within the framework of linear noise approximation. The resultant analytical expression of phosphorylated response regulators are then used to quantify the noise profile of biologically motivated single and branched pathways. Enhancement and reduction of noise in terms of extra phosphate outflux and influx, respectively, have been analyzed for the branched system. Furthermore, the role of fluctuations of the network output in the regulation of a promoter with random activation-deactivation dynamics has been analyzed.

Maity, Alok Kumar; Bandyopadhyay, Arnab; Chattopadhyay, Sudip; Chaudhuri, Jyotipratim Ray; Metzler, Ralf; Chaudhury, Pinaki; Banik, Suman K.

2013-09-01

308

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

PubMed Central

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

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

2014-01-01

309

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

PubMed Central

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

2011-01-01

310

On the Molecular Basis of D-Bifunctional Protein Deficiency Type III  

PubMed Central

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

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

2013-01-01

311

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

PubMed

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

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

2014-01-01

312

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

PubMed

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 ?-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

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

2014-07-01

313

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

SciTech Connect

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.

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

314

Development of tartaric esters as bifunctional additives of methanol-gasoline  

PubMed Central

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

2014-01-01

315

Chimeric bifunctional oligonucleotides as a novel tool to invade telomerase assembly  

PubMed Central

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

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

2014-01-01

316

Design and validation of a bifunctional ligand display system for receptor targeting.  

PubMed

Here we developed a bacteriophage display particle designed to serve as a bifunctional entity that can target tumors while delivering an agent. We engineered a chimera phage vector containing a pIII-displayed alphav integrins-targeting moiety and a pVIII-displayed streptavidin binding adaptor moiety. By using the chimeric phage particle, targeting of alphav integrins on cells in culture and tumor-related blood vessels was shown through different applications, including luminescent quantum dots localization, surface plasmon resonance-based binding detection, and an in vivo tumor model. The strategy validated here will accelerate the discovery and characterization of receptor-ligand binding events in high throughput, and cell-specific delivery of diagnostics or therapeutics to organs of choice without the need for chemical conjugation. PMID:15324809

Chen, Limor; Zurita, Amado J; Ardelt, Peter U; Giordano, Ricardo J; Arap, Wadih; Pasqualini, Renata

2004-08-01

317

Fabrication of bifunctional core-shell Fe3O4 particles coated with ultrathin phosphor layer  

PubMed Central

Bifunctional monodispersed Fe3O4 particles coated with an ultrathin Y2O3:Tb3+ shell layer were fabricated using a facile urea-based homogeneous precipitation method. The obtained composite particles were characterized by powder X-ray diffraction, transmission electron microscopy (TEM), quantum design vibrating sample magnetometry, and photoluminescence (PL) spectroscopy. TEM revealed uniform spherical core-shell-structured composites ranging in size from 306 to 330 nm with a shell thickness of approximately 25 nm. PL spectroscopy confirmed that the synthesized composites displayed a strong eye-visible green light emission. Magnetic measurements indicated that the composite particles obtained also exhibited strong superparamagnetic behavior at room temperature. Therefore, the inner Fe3O4 core and outer Y2O3:Tb3+ shell layer endow the composites with both robust magnetic properties and strong eye-visible luminescent properties. These composite materials have potential use in magnetic targeting and bioseparation, simultaneously coupled with luminescent imaging. PMID:23962025

2013-01-01

318

Chimeric gene construct coding for bi-functional enzyme endowed with endoglucanase and phytase activities.  

PubMed

Phytase and endoglucanase enzymes are being widely used as feed additives in poultry industry. In our earlier studies, the Bacillus phytase, when expressed in Escherichia coli, was found in inclusion bodies, whereas endoglucanase was found in active soluble form. Herein, we report the development of a chimeric gene construct coding for ~73 kDa fusion protein and its over-expression in E. coli in soluble form. The novel enzyme exhibited both endoglucanase and phytase activities across broad pH (4.0-8.0) and temperature (25-75 degrees C) ranges. As such, the bi-functional enzyme seems promising and might serve as a potential feed additive for enhanced nutrition uptake in monogastric animals. PMID:18987844

Reddy, V Arunodai; Venu, K; Rao, D E C S; Rao, K V; Reddy, V D

2009-02-01

319

Ontogenetic Habitat Shifts of Juvenile Bear Lake Sculpin  

Microsoft Academic Search

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

James R. Ruzycki; Wayne A. Wurtsbaugh

1999-01-01

320

Grease Inhibits Stress-Corrosion Cracking In Bearing Race  

NASA Technical Reports Server (NTRS)

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.

Beatty, Robert F.; Mcvey, Scott E.

1991-01-01

321

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

Microsoft Academic Search

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 30000 rpm. Increases in radial clearance were accomplished by reducing the

Kevin Radil; Samuel Howard; Brian Dykas

2002-01-01

322

AmpH, a Bifunctional dd-Endopeptidase and dd-Carboxypeptidase of Escherichia coli?  

PubMed Central

In Escherichia coli, low-molecular-mass penicillin-binding proteins (LMM PBPs) are important for correct cell morphogenesis. These enzymes display dd-carboxypeptidase and/or dd-endopeptidase activities associated with maturation and remodeling of peptidoglycan (PG). AmpH has been classified as an AmpH-type class C LMM PBP, a group closely related to AmpC ?-lactamases. AmpH has been associated with PG recycling, although its enzymatic activity remained uncharacterized until now. Construction and purification of His-tagged AmpH from E. coli permitted a detailed study of its enzymatic properties. The N-terminal export signal of AmpH is processed, but the protein remains membrane associated. The PBP nature of AmpH was demonstrated by its ability to bind the ?-lactams Bocillin FL (a fluorescent penicillin) and cefmetazole. In vitro assays with AmpH and specific muropeptides demonstrated that AmpH is a bifunctional dd–endopeptidase and dd-carboxypeptidase. Indeed, the enzyme cleaved the cross-linked dimers tetrapentapeptide (D45) and tetratetrapeptide (D44) with efficiencies (kcat/Km) of 1,200 M?1 s?1 and 670 M?1 s?1, respectively, and removed the terminal d-alanine from muropeptides with a C-terminal d-Ala-d-Ala dipeptide. Both dd-peptidase activities were inhibited by 40 ?M cefmetazole. AmpH also displayed a weak ?-lactamase activity for nitrocefin of 1.4 × 10?3 nmol/?g protein/min, 1/1,000 the rate obtained for AmpC under the same conditions. AmpH was also active on purified sacculi, exhibiting the bifunctional character that was seen with pure muropeptides. The wide substrate spectrum of the dd-peptidase activities associated with AmpH supports a role for this protein in PG remodeling or recycling. PMID:22001512

González-Leiza, Silvia M.; de Pedro, Miguel A.; Ayala, Juan A.

2011-01-01

323

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

PubMed Central

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

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

2011-01-01

324

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

SciTech Connect

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.

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

2007-11-11

325

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

SciTech Connect

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.

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

1984-01-01

326

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

SciTech Connect

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

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

1991-03-01

327

Novel 16-substituted bifunctional derivatives of huperzine B: multifunctional cholinesterase inhibitors  

PubMed Central

Aim: To design novel bifunctional derivatives of huperzine B (HupB) based on the concept of dual binding site of acetylcholinesterase (AChE) and evaluate their pharmacological activities for seeking new drug candidates against Alzheimer's disease (AD). Methods: Novel 16-substituted bifunctional derivatives of HupB were synthesized through chemical reactions. The inhibitory activities of the derivatives toward AChE and butyrylcholinesterase (BuChE) were determined in vitro by modified Ellman's method. Cell viability was quantified by the reduction of MTT. Results: A new preparative method was developed for the generation of 16-substituted derivatives of HupB, and pharmacological trials indicated that the derivatives were multifunctional cholinesterase inhibitors targeting both AChE and BuChE. Among the derivatives tested, 9c, 9e, 9f, and 9i were 480 to 1360 times more potent as AChE inhibitors and 370 to 1560 times more potent as BuChE inhibitors than the parent HupB. Further preliminary pharmacological trials of derivatives 9c and 9i were performed, including examining the mechanism of AChE inhibition, the substrate kinetics of the enzyme inhibition, and protection against hydrogen peroxide (H2O2)-induced cytotoxicity in PC12 cells. Conclusion: Preliminary pharmacological evaluation indicated that 16-substituted derivatives of HupB, particularly 9c and 9i, would be potentially valuable new drug candidates for AD therapy, and further exploration is needed to evaluate their pharmacological and clinical efficacies. PMID:19578388

Shi, Yu-fang; Zhang, Hai-yan; Wang, Wei; Fu, Yan; Xia, Yu; Tang, Xi-can; Bai, Dong-lu; He, Xu-chang

2009-01-01

328

Synthesis of Dithio-Diphosphine (P2S2COOH)Based Bifunctional Chelating Agent. Its Coupling Reactions with Peptide Analogs and Steroids  

Microsoft Academic Search

Bifunctional chelating agents are important in the development of site-specific radiopharmaceuticals for diagnosis and therapy of cancer. Recently. our Laboratory has developed a new dithio-diphosphine (P2S2COOH)-based bifunctional chelating agent [1]. Its coupling to biologically important molecules such as peptide analogs and steroids have been investigated in detail (Scheme I). The intermediate compound P2S2 phosphine hydride 3 was synthesized as described

Hariprasad Gali; Srinivasa R. Karra; Sreenivasa V. Reedy; Roger Schilbli; Wynn A. Volkert; Kattesh V. Katti

1999-01-01

329

Mixed-mu superconducting bearings  

DOEpatents

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.

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

1998-03-03

330

Mixed-mu superconducting bearings  

DOEpatents

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.

Hull, John R. (Hinsdale, IL); Mulcahy, Thomas M. (Western Springs, IL)

1998-01-01

331

ATM CMG bearing failure analysis  

NASA Technical Reports Server (NTRS)

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).

1975-01-01

332

Teddy Bear Line-Up  

NSDL National Science Digital Library

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

333

Lateral dampers for thrust bearings  

NASA Technical Reports Server (NTRS)

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.

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

1985-01-01

334

Improved Superconducting Magnetic Rotary Bearings  

NASA Technical Reports Server (NTRS)

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

Flom, Yury; Royston, James

1992-01-01

335

Testing and Lubrication for Single Race Bearings  

SciTech Connect

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.

Steinhoff, R.G.

1998-03-04

336

Application of space technology to X-ray tube bearings  

SciTech Connect

This paper describes work done to transfer technology, developed during the SP100 Space Reactor program, to commercial applications. The SP100 program was intended to develop a high temperature nuclear reactor power source for space applications. The specific area described in this paper is the use of high temperature bearings and lubricants under vacuum conditions. At the instigation of the Jet Propulsion Laboratory, a joint program was initiated between Varian Corporation and Advanced Methods and Materials Co. (AMM); with AMM providing the technical expertise in high temperature bearing technology, acquired during the Sp100 program, and Varian providing the testing and performance evaluation of the completed bearing assemblies. The Varian bearing application is X-ray tubes. The tungsten target is required to rotate within the vacuum tube with the bearings operating at temperatures in the region of 300 C. The high temperature vacuum conditions preclude the use of any organic lubricants. The desired improvements in bearing performance were in the areas of noise reduction and extended lifetime. The SP100 program had required low friction ball bearings for the Control Drive Assembly motors, clutches and brakes. These assemblies were required to operate at 540 C in hard vacuum. For the SP100 program silver coated tool steel bearings were tested along with molybdenum disulfide coated Stellite L605 races and balls with molybdenum disulfide coated Stellite L605 races with silicon nitride balls. The work described in this paper covers the results from the SP100 tests and describes the application of this technology to the Varian X-ray tubes using optimized MoS{sub 2} deposition parameters. The results of this work to date and the conclusions resulting from the endurance testing are described in detail.

Ring, P.J. [Advanced Methods and Materials Co., San Jose, CA (United States); Virshup, G.F. [Varian Associates, Palo Alto, CA (United States)

1996-12-31

337

SSME Long-life Bearings  

NASA Technical Reports Server (NTRS)

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).

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

1986-01-01

338

Stability of finite journal bearings from bearings--linear and nonlinear bearing forces  

NASA Astrophysics Data System (ADS)

The paper investigates the relationship between the stability contour determined from the nonlinear simulation and that from the linear theory. The nonlinear bearing forces are directly obtained from the bearing pressure distribution which is solved from the Reynolds equation at each journal position. It is found that the critical speeds in the case of nonlinear bearing forces are the same as those predicted by the linear theory, although the whirl loci under large dynamic excitations are significantly different from those arising from the linear bearing forces. Typical whirling trajectories under impact excitation, positionperturbation and synchronous unbalance excitations are simulated and presented to explain the stable, critical and unstable phenomena. The whirl displacement signals are also transformed to the frequency domain, and their whirling frequencies are analyzed according to their frequency characteristics.

Tieu, A. K.; Qiu, Z. L.

1995-07-01

339

Ball Bearings Equipped for In Situ Lubrication on Demand  

NASA Technical Reports Server (NTRS)

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

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

2005-01-01

340

Journal gas bearing for curved surfaces  

NASA Technical Reports Server (NTRS)

Optimizing bearing length and permissible axis curvature alleviates distortion of film gap of gas lubricated journal bearing in deployment mechanisms. Required bearing length is divided into two shorter bearings interconnected by links which allow satisfactory conformity with the bent, load-carrying member.

Redmon, J. W.

1969-01-01

341

Ball-and-Socket-Bearing Wear Test  

NASA Technical Reports Server (NTRS)

Series of experiments to measure wear life of spherical bearing summarized. Report designed to establish clearance, contour, finish, and lubricant parameters for highly-loaded, compact plain spherical bearing. Information useful in design of bearings for helicopter control linkages, business machines, nuclear reactor, and rotor bearings.

Graham, W. G.

1984-01-01

342

Hydrostatic bearings for a turbine fluid flow metering device  

DOEpatents

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.

Fincke, James R. (Rigby, ID)

1982-01-01

343

Hydrostatic bearings for a turbine fluid flow metering device  

DOEpatents

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.

Fincke, J.R.

1982-05-04

344

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

PubMed

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

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

2012-04-14

345

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

PubMed Central

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

Martín, Carmen

2014-01-01

346

Cryogenic Magnetic Bearing Test Facility (CMBTF)  

NASA Technical Reports Server (NTRS)

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.

1992-01-01

347

Pt\\/H-beta zeolites as productive bifunctional catalysts for the one-step citronellal-to-menthol conversion  

Microsoft Academic Search

Pt-loaded H-beta zeolite was identified as a highly active catalyst for the bifunctional transformation of citronellal to menthol, with isopulegol as the intermediate. With a 2 wt% Pt-loaded catalyst, citronellal is fully converted within 12 h, with only 2.5 wt% catalyst with respect to citronellal, and with a citronellal to Pt molar ratio of 2500. 1,4-Dioxane is the best reaction

Pascal Mertens; Francis Verpoort; Andrei-Nicolae Parvulescu; Dirk De Vos

2006-01-01

348

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

PubMed Central

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

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

2010-01-01

349

Application of bifunctional Saccharomyces cerevisiae to remove lead(II) and cadmium(II) in aqueous solution  

Microsoft Academic Search

A magnetic adsorbent, EDTAD-functionalized Saccharomyces cerevisiae, has been synthesized to behave as an adsorbent for heavy metal ions by adjusting the pH value of the aqueous solution to make carboxyl and amino groups protonic or non-protonic. The bifunctional Saccharomyces cerevisiae (EMS) were used to remove lead(II) and cadmium(II) in solution in a batch system. The results showed that the adsorption

Yunsong Zhang; Weiguo Liu; Li Zhang; Meng Wang; Maojun Zhao

2011-01-01

350

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

Microsoft Academic Search

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

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

1996-01-01

351

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

PubMed

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

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

2015-01-14

352

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

Microsoft Academic Search

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

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

1992-01-01

353

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

NASA Technical Reports Server (NTRS)

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

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

2006-01-01

354

Improving Metabolic Stability By Glycosylation: Bifunctional Peptide Derivatives That Are Opioid Receptor Agonists and Neurokinin 1 Receptor Antagonists  

PubMed Central

In order to obtain a metabolically more stable analgesic peptide derivative, O-?-glycosylated serine (Ser(Glc)) was introduced into TY027 (Tyr-D-Ala-Gly-Phe-Met-Pro-Leu-Trp-NH-3’,5’-Bzl(CF3)2) which was a previously reported bifunctional compound with delta/mu opioid agonist and neurokinin-1 receptor antagonist activities, and with a half life of 4.8 h in rat plasma. Incorporation of Ser(Glc) into various positions of TY027 gave analogues with variable bioactivities. Analogue 6 (Tyr-D-Ala-Gly-Phe-Nle-Pro-Leu-Ser(Glc)-Trp-NH-3’,5’-Bzl(CF3)2) was found to have effective bifunctional activities with a well-defined conformation with two ?-turns based on the NMR conformational analysis in the presence of DPC micelles. In addition, 6 showed significant improvement in its metabolic stability (70 ± 9 % of 6 was intact after 24 h incubation in rat plasma). This improved metabolic stability, along with its effective and delta selective bifunctional activities, suggests that 6 could be an interesting research tool and possibly a promising candidate as a novel analgesic drug. PMID:20560643

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

2012-01-01

355

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

PubMed Central

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

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

2010-01-01

356

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

NASA Astrophysics Data System (ADS)

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

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

2014-12-01

357

Activity modulation of core and shell in nanozeolite@enzyme bi-functional catalyst for dynamic kinetic resolution.  

PubMed

A core-shell nanozeolite@enzyme bi-functional catalyst is prepared by using nanozeolite ? as acidic core and immobilized Candida antarctica lipase B (CALB) as enzyme shell for the purpose of dynamic kinetic resolution (DKR), and polydiallyldimethylammonium chloride (PDDA) is used as interlayer to compart core and shell. The activities of core and shell in bi-functional catalyst are modulated to achieve the matching between racemization and kinetic resolution (KR) rates in DKR, i.e., a slow racemization rate on core while a fast KR rate on shell. Nanozeolite ? with intermediate SiO2/Al2O3 ratio provides proper acid amount for racemization step. A relatively thick layer of PDDA not only improves the activity of CALB by its coverage for surface acidic sites but also limits the accessibility and diffusion of substrate towards the acidic core. The CALB shell with larger immobilized amount and higher enzyme activity offers enhanced driving force of DKR process, leading to higher conversion, selectivity and yield. The preparation and activity modulation of core-shell catalyst provide an ideal method to improve the catalytic performance of bi-functional catalyst. PMID:25454421

Li, Xiang; Yan, Yueer; Wang, Wanlu; Zhang, Yahong; Tang, Yi

2015-01-15

358

Superconductor bearings, flywheels and transportation  

NASA Astrophysics Data System (ADS)

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.

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

2012-01-01

359

EXCITATION OF STRUCTURAL RESONANCE DUE TO A BEARING FAILURE  

SciTech Connect

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 bearing were multiples of each other. This resonant condition was detected before other damage occurred, and further damage due to the resonant condition was prevented through vibration analysis.

Leishear, R; David Stefanko, D

2007-04-30

360

Magnetic bearings with zero bias  

NASA Technical Reports Server (NTRS)

A magnetic bearing operating without a bias field has supported a shaft rotating at speeds up to 12,000 rpm with the usual four power supplies and with only two. A magnetic bearing is commonly operated with a bias current equal to half of the maximum current allowable in its coils. This linearizes the relation between net force and control current and improves the force slewing rate and hence the band width. The steady bias current dissipates power, even when no force is required from the bearing. The power wasted is equal to two-thirds of the power at maximum force output. Examined here is the zero bias idea. The advantages and disadvantages are noted.

Brown, Gerald V.; Grodsinsky, Carlos M.

1991-01-01

361

Cloning and characterization of bifunctional enzyme farnesyl diphosphate/geranylgeranyl diphosphate synthase from Plasmodium falciparum  

PubMed Central

Background Isoprenoids are the most diverse and abundant group of natural products. In Plasmodium falciparum, isoprenoid synthesis proceeds through the methyl erythritol diphosphate pathway and the products are further metabolized by farnesyl diphosphate synthase (FPPS), turning this enzyme into a key branch point of the isoprenoid synthesis. Changes in FPPS activity could alter the flux of isoprenoid compounds downstream of FPPS and, hence, play a central role in the regulation of a number of essential functions in Plasmodium parasites. Methods The isolation and cloning of gene PF3D7_18400 was done by amplification from cDNA from mixed stage parasites of P. falciparum. After sequencing, the fragment was subcloned in pGEX2T for recombinant protein expression. To verify if the PF3D7_1128400 gene encodes a functional rPfFPPS protein, its catalytic activity was assessed using the substrate [4-14C] isopentenyl diphosphate and three different allylic substrates: dimethylallyl diphosphate, geranyl diphosphate or farnesyl diphosphate. The reaction products were identified by thin layer chromatography and reverse phase high-performance liquid chromatography. To confirm the product spectrum formed of rPfFPPS, isoprenic compounds were also identified by mass spectrometry. Apparent kinetic constants KM and Vmax for each substrate were determined by Michaelis–Menten; also, inhibition assays were performed using risedronate. Results The expressed protein of P. falciparum FPPS (rPfFPPS) catalyzes the synthesis of farnesyl diphosphate, as well as geranylgeranyl diphosphate, being therefore a bifunctional FPPS/geranylgeranyl diphosphate synthase (GGPPS) enzyme. The apparent KM values for the substrates dimethylallyl diphosphate, geranyl diphosphate and farnesyl diphosphate were, respectively, 68?±?5 ?M, 7.8?±?1.3 ?M and 2.06?±?0.4 ?M. The protein is expressed constitutively in all intra-erythrocytic stages of P. falciparum, demonstrated by using transgenic parasites with a haemagglutinin-tagged version of FPPS. Also, the present data demonstrate that the recombinant protein is inhibited by risedronate. Conclusions The rPfFPPS is a bifunctional FPPS/GGPPS enzyme and the structure of products FOH and GGOH were confirmed mass spectrometry. Plasmodial FPPS represents a potential target for the rational design of chemotherapeutic agents to treat malaria. PMID:23734739

2013-01-01

362

The Great Bear Rainforest Spirit Bears, Grizzlies and Ancient Forests  

E-print Network

-old western red cedars. 22 conted.ucalgary.ca/travelprograms|403.220.2952 #12;Orientation The orientation's sea lions, and the biological complexity of the intertidal zone. Itinerary Three meals daily private 12-passenger boat to search for grizzly bears fishing for salmon, an amusing and entertaining

de Leon, Alex R.

363

Nonlinear dynamics of attractive magnetic bearings  

NASA Technical Reports Server (NTRS)

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.

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

1987-01-01

364

Application of computational fluid dynamics on cavitation in journal bearings  

NASA Astrophysics Data System (ADS)

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

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

2014-03-01

365

Wave Journal Bearing. Part 1: Analysis  

NASA Technical Reports Server (NTRS)

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.

Dimofte, Florin

1995-01-01

366

Report on the biological monitoring program for Bear Creek at the Oak Ridge Y-12 Plant, Oak Ridge, Tennessee, 1989-1994  

SciTech Connect

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.

Hinzman, R.L. [ed.] [ed.; Beauchamp, J.J.; Cada, G.F.; Peterson, M.J. [and others] [and others

1996-04-01

367

Initiatives Programs  

Cancer.gov

Skip to Content Home | Investigator Resources | Protocol Development | Initiatives/Programs/Collaborations | Links to More Resources | Funding Opportunities | About CTEP Home | Sitemap | Contact CTEP Search this site Initiatives / Programs National

368

Transient Ru-methyl formate intermediates generated with bifunctional transfer hydrogenation catalysts  

PubMed Central

Desorption electrospray ionization (DESI) coupled to high-resolution Orbitrap mass spectrometry (MS) was used to study the reactivity of a (?-amino alcohol)(arene)RuCl transfer hydrogenation catalytic precursor in methanol (CH3OH). By placing [(p-cymene)RuCl2]2 on a surface and spraying a solution of ?-amino alcohol in methanol, two unique transient intermediates having lifetimes in the submillisecond to millisecond range were detected. These intermediates were identified as Ru (II) and Ru (IV) complexes incorporating methyl formate (HCOOCH3). The Ru (IV) intermediate is not observed when the DESI spray solution is sparged with Ar gas, indicating that O2 dissolved in the solvent is necessary for oxidizing Ru (II) to Ru (IV). These proposed intermediates are supported by high-resolution and high mass accuracy measurements and by comparing experimental to calculated isotope profiles. Additionally, analyzing the bulk reaction mixture using gas chromatography-MS and nuclear magnetic resonance spectroscopy confirms the formation of HCOOCH3. These results represent an example that species generated from the (?-amino alcohol)(arene)RuCl (II) catalytic precursor can selectively oxidize CH3OH to HCOOCH3. This observation leads us to propose a pathway that can compete with the hydrogen transfer catalytic cycle. Although bifunctional hydrogen transfer with Ru catalysts has been well-studied, the ability of DESI to intercept intermediates formed in the first few milliseconds of a chemical reaction allowed identification of previously unrecognized intermediates and reaction pathways in this catalytic system. PMID:22315417

Perry, Richard H.; Brownell, Kristen R.; Chingin, Konstantin; Cahill, Thomas J.; Waymouth, Robert M.; Zare, Richard N.

2012-01-01

369

Photoluminescent lead(II) coordination polymers stabilised by bifunctional organoarsonate ligands  

NASA Astrophysics Data System (ADS)

Four lead(II) coordination polymers were isolated under hydro(solvo)thermal conditions. The applied synthetic methodology takes advantage of the coordination behaviour of a new bifunctional organoarsonate ligand, 4-(1, 2, 4-triazol-4-yl)phenylarsonic acid (H2TPAA) and involves the variation of lead(II) reactants, metal/ligand mole ratios, and solvents. The constitutional composition of the four lead(II) coordination polymers can be formulated as [Pb2(TPAA)(HTPAA)(NO3)]·6H2O (1), [Pb2(TPAA)(HTPAA)2]·DMF·0.5H2O (DMF = N, N-Dimethylformamide) (2), [Pb2Cl2(TPAA)H2O] (3), and [Pb3Cl(TPAA)(HTPAA)2H2O]Cl (4). The compounds were characterized by single-crystal and powder x-ray diffraction techniques, thermogravimetric analyses, infra-red spectroscopy, and elemental analyses. Single-crystal x-ray diffraction reveals that 1 and 2 represent two-dimensional (2D) layered structures whilst 3 and 4 form three-dimensional (3D) frameworks. The structures of 1, 2, and 4 contain one-dimensional (1D) {PbII/AsO3} substructures, while 3 is composed of 2D {PbII/AsO3} arrays. Besides their interesting topologies, 1–4 all exhibit photoluminescence properties in the solid state at room temperature.

Lin, Jian-Di; Onet, Camelia I.; Schmitt, Wolfgang

2015-04-01

370

Biosynthesis of riboflavin: characterization of the bifunctional deaminase-reductase of Escherichia coli and Bacillus subtilis.  

PubMed Central

The ribG gene at the 5' end of the riboflavin operon of Bacillus subtilis and a reading frame at 442 kb on the Escherichia coli chromosome (subsequently designated ribD) show similarity with deoxycytidylate deaminase and with the RIB7 gene of Saccharomyces cerevisiae. The ribG gene of B. subtilis and the ribD gene of E. coli were expressed in recombinant E. coli strains and were shown to code for bifunctional proteins catalyzing the second and third steps in the biosynthesis of riboflavin, i.e., the deamination of 2,5-diamino-6-ribosylamino-4(3H)-pyrimidinone 5'-phosphate (deaminase) and the subsequent reduction of the ribosyl side chain (reductase). The recombinant proteins specified by the ribD gene of E. coli and the ribG gene of B. subtilis were purified to homogeneity. NADH as well as NADPH can be used as a cosubstrate for the reductase of both microorganisms under study. Expression of the N-terminal or C-terminal part of the RibG protein yielded proteins with deaminase or reductase activity, respectively; however, the truncated proteins were rather unstable. PMID:9068650

Richter, G; Fischer, M; Krieger, C; Eberhardt, S; Lüttgen, H; Gerstenschläger, I; Bacher, A

1997-01-01

371

Recombination, RNA evolution, and bifunctional RNA molecules isolated through chimeric SELEX.  

PubMed Central

Exchange of RNA structural domains through recombination can be used to engineer RNAs with novel functions and may have played an important role in the early evolution of life. The degree of function an RNA element retains upon recombination into a new sequence context is a measure of how deleterious or beneficial recombination will be. When we fused pairs of aptamers previously selected to bind coenzyme A, chloramphenicol, or adenosine, the chimerae retained some ability to bind both targets, but with reduced binding activity both in solution and on affinity resins, probably due to misfolding. Complex populations of recombined RNAs gave similar results. Applying dual selection pressure to recombined populations yielded the combinations that were best suited to binding both targets. Most reselected RNAs folded into the active conformation more readily than chimerae built from arbitrarily chosen aptamers, as indicated both by solution Kd measurements and affinity resin binding activity. Deletion/selection experiments confirmed that the sequences required for binding are fully contained within the respective domains and not derived from interaction between the domains, consistent with the modular architecture of their original design. The combinatorial nature of the recombination methods presented here takes advantage of the full sequence diversity of the starting populations and yields large numbers of bifunctional molecules (10(6) to more than 1012). The method can be easily generalized and should be applicable to engineering dual-function RNAs for a wide variety of applications, including catalysis, novel therapeutics, and studies of long-range RNA structure. PMID:9740133

Burke, D H; Willis, J H

1998-01-01

372

Skeletal isomerization of n-heptane and hydroisomerization of benzene over bifunctional heteropoly compounds  

Microsoft Academic Search

Hydroisomerization of benzene and skeletal isomerization of n-heptane have been studied using various 2wt.% Pt-promoted solid acids such as Pt–Cs2.5H0.5PW12O40 (Pt–Cs2.5), SiO2 supported Pt–Cs2.5H0.5PW12O40 (Pt–Cs2.5\\/SiO2), Pt–SO42?\\/ZrO2, Pt–WO3\\/ZrO2, and Pt–H-? zeolite. The catalytic activity for the formation of methylcyclopentane in the hydroisomerization of benzene was in order of Pt–Cs2.5\\/SiO2>Pt–Cs2.5>Pt–WO3\\/ZrO2>Pt–SO42?\\/ZrO2. The highest activity of Pt–Cs2.5\\/SiO2 among these bifunctional catalysts would be due

Atsuyuki Miyaji; Toshio Okuhara

2003-01-01

373

BIFUNCTIONAL CATALYSTS FOR THE SELECTIVE CATALYTIC REDUCTION OF NO BY HYDROCARBONS  

SciTech Connect

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

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

2003-08-24

374

Impedimetric and amperometric bifunctional glucose biosensor based on hybrid organic-inorganic thin films.  

PubMed

A novel glucose biosensor with an immobilized mediator was studied using electrochemical impedance spectroscopy (EIS) and amperometry measurements. The biosensor has a characteristic ultrathin form and is composed of a self-assembled monolayer anchoring glucose oxidase (GOx) covered with Langmuir-Blodgett (LB) films of Prussian blue (PB). The immobilized PB in the LB films acts as a mediator and enables the biosensor to work under a low potential (0.0V vs. Ag/AgCl). In the EIS measurements, a dramatic decrease in charge transfer resistance (Rct) was observed with sequential addition of glucose, which can be attributed to enzymatic activity. The linearity of the biosensor response was observed by the variation of the sensor response (1/Rct) as a function of glucose concentration in the range 0 to 25mM. The sensor also showed linear amperometric response below 130mM glucose. The organic-inorganic system of GOx and PB nanoclusters demonstrated bifunctional sensing action, both amperometry and EIS modes, as well as long sensing stability for 4 days. PMID:25014167

Wang, Huihui; Ohnuki, Hitoshi; Endo, Hideaki; Izumi, Mitsuru

2015-02-01

375

Engineering the robustness of Saccharomyces cerevisiae by introducing bifunctional glutathione synthase gene.  

PubMed

Robust, high-yielding Saccharomyces cerevisiae is highly desirable for cost-effective cellulosic ethanol production. In this study, the bifunctional glutathione (GSH) synthetase genes GCSGS at high copy number was integrated into ribosomal DNA of S. cerevisiae by Cre-LoxP system. Threefold higher GSH contents (54.9 ?mol/g dry weight) accumulated in the engineered strain BY-G compared to the reference strain. Tolerance of BY-G to H2O2 (3 mM), temperature (40 °C), furfural (10 mM), hydroxymethylfurfural (HMF, 10 mM) and 0.5 mM Cd(2+) increased compared to reference strain. Twofold higher ethanol concentration was obtained by BY-G in simultaneous saccharification and fermentation of corn stover compared to the reference strain. The results showed that intracellular GSH content of S. cerevisiae has an influence on robustness. The strategy is used to engineer S. cerevisiae strains adaptive to a combination of tolerance to inhibitors and raised temperature that may occur in high solid simultaneous saccharification and fermentation of lignocellulosic feedstocks. PMID:25561319

Qiu, Zhiqi; Deng, Zujun; Tan, Hongming; Zhou, Shining; Cao, Lixiang

2015-04-01

376

Chrysanthemyl diphosphate synthase operates in planta as a bifunctional enzyme with chrysanthemol synthase activity.  

PubMed

Chrysanthemyl diphosphate synthase (CDS) is the first pathway-specific enzyme in the biosynthesis of pyrethrins, the most widely used plant-derived pesticide. CDS catalyzes c1'-2-3 cyclopropanation reactions of two molecules of dimethylallyl diphosphate (DMAPP) to yield chrysanthemyl diphosphate (CPP). Three proteins are known to catalyze this cyclopropanation reaction of terpene precursors. Two of them, phytoene and squalene synthase, are bifunctional enzymes with both prenyltransferase and terpene synthase activity. CDS, the other member, has been reported to perform only the prenyltransferase step. Here we show that the NDXXD catalytic motif of CDS, under the lower substrate conditions prevalent in plants, also catalyzes the next step, converting CPP into chrysanthemol by hydrolyzing the diphosphate moiety. The enzymatic hydrolysis reaction followed conventional Michaelis-Menten kinetics, with a Km value for CPP of 196 ?m. For the chrysanthemol synthase activity, DMAPP competed with CPP as substrate. The DMAPP concentration required for half-maximal activity to produce chrysanthemol was ?100 ?m, and significant substrate inhibition was observed at elevated DMAPP concentrations. The N-terminal peptide of CDS was identified as a plastid-targeting peptide. Transgenic tobacco plants overexpressing CDS emitted chrysanthemol at a rate of 0.12-0.16 ?g h(-1) g(-1) fresh weight. We propose that CDS should be renamed a chrysanthemol synthase utilizing DMAPP as substrate. PMID:25378387

Yang, Ting; Gao, Liping; Hu, Hao; Stoopen, Geert; Wang, Caiyun; Jongsma, Maarten A

2014-12-26

377

Three crystal forms of the bifunctional enzyme proline utilization A (PutA) from Bradyrhizobium japonicum.  

PubMed

Proline utilization A proteins (PutAs) are large (1000-1300 residues) membrane-associated bifunctional flavoenzymes that catalyze the two-step oxidation of proline to glutamate by the sequential action of proline dehydrogenase and Delta(1)-pyrroline-5-carboxylate dehydrogenase domains. Here, the first successful crystallization efforts for a PutA protein are described. Three crystal forms of PutA from Bradyrhizobium japonicum are reported: apparent tetragonal, hexagonal and centered monoclinic. The apparent tetragonal and hexagonal crystals were grown in the presence of PEG 3350 and sodium formate near pH 7. The apparent tetragonal form diffracted to 2.7 A resolution and exhibited pseudo-merohedral twinning such that the true space group is P2(1)2(1)2(1) with four molecules in the asymmetric unit. The hexagonal form diffracted to 2.3 A resolution and belonged to space group P6(2)22 with one molecule in the asymmetric unit. Centered monoclinic crystals were grown in ammonium sulfate, diffracted to 2.3 A resolution and had two molecules in the asymmetric unit. Removing the histidine tag was important in order to obtain the C2 crystal form. PMID:18931443

Schuermann, Jonathan P; White, Tommi A; Srivastava, Dhiraj; Karr, Dale B; Tanner, John J

2008-10-01

378

Crystal structure of the bifunctional proline utilization A flavoenzyme from Bradyrhizobium japonicum  

PubMed Central

The bifunctional proline catabolic flavoenzyme, proline utilization A (PutA), catalyzes the oxidation of proline to glutamate via the sequential activities of FAD-dependent proline dehydrogenase (PRODH) and NAD+-dependent ?1-pyrroline-5-carboxylate dehydrogenase (P5CDH) domains. Although structures for some of the domains of PutA are known, a structure for the full-length protein has not previously been solved. Here we report the 2.1 ? resolution crystal structure of PutA from Bradyrhizobium japonicum, along with data from small-angle x-ray scattering, analytical ultracentrifugation, and steady-state and rapid-reaction kinetics. PutA forms a ring-shaped tetramer in solution having a diameter of 150 ?. Within each protomer, the PRODH and P5CDH active sites face each other at a distance of 41 ? and are connected by a large, irregularly shaped cavity. Kinetics measurements show that glutamate production occurs without a lag phase, suggesting that the intermediate, ?1-pyrroline-5-carboxylate, is preferably transferred to the P5CDH domain rather than released into the bulk medium. The structural and kinetic data imply that the cavity serves both as a microscopic vessel for the hydrolysis of ?1-pyrroline-5-carboxylate to glutamate semialdehyde and a protected conduit for the transport of glutamate semialdehyde to the P5CDH active site. PMID:20133651

Srivastava, Dhiraj; Schuermann, Jonathan P.; White, Tommi A.; Krishnan, Navasona; Sanyal, Nikhilesh; Hura, Greg L.; Tan, Anmin; Henzl, Michael T.; Becker, Donald F.; Tanner, John J.

2010-01-01

379

Three crystal forms of the bifunctional enzyme proline utilization A (PutA) from Bradyrhizobium japonicum  

PubMed Central

Proline utilization A proteins (PutAs) are large (1000–1300 residues) membrane-associated bifunctional flavoenzymes that catalyze the two-step oxidation of proline to glutamate by the sequential action of proline dehydrogenase and ?1-pyrroline-5-carboxylate dehydrogenase domains. Here, the first successful crystallization efforts for a PutA protein are described. Three crystal forms of PutA from Bradyrhizobium japonicum are reported: apparent tetragonal, hexagonal and centered monoclinic. The apparent tetragonal and hexagonal crystals were grown in the presence of PEG 3350 and sodium formate near pH 7. The apparent tetragonal form diffracted to 2.7?Å resolution and exhibited pseudo-merohedral twinning such that the true space group is P212121 with four molecules in the asymmetric unit. The hexagonal form diffracted to 2.3?Å resolution and belonged to space group P6222 with one molecule in the asymmetric unit. Centered monoclinic crystals were grown in ammonium sulfate, diffracted to 2.3?Å resolution and had two molecules in the asymmetric unit. Removing the histidine tag was important in order to obtain the C2 crystal form. PMID:18931443

Schuermann, Jonathan P.; White, Tommi A.; Srivastava, Dhiraj; Karr, Dale B.; Tanner, John J.

2008-01-01

380

Design, synthesis, and biological evaluation of a series of bifunctional ligands of opioids/SSRIs.  

PubMed

A series of opioid and serotonin re-uptake inhibitors (SSRIs) bifunctional ligands have been designed, synthesized, and tested for their activities and efficacies at ?-, ?- and ? opioid receptors and SSRIs receptors. Most of the compounds showed high affinities for ?- and ?-opioid receptors and lower affinities for SSRIs and ? opioid receptors. A docking study on the ?-opioid receptor binding pocket has been carried out for ligands 3-11. The ligands 7 and 11 have displayed the highest binding profiles for the ?-opioid receptor binding site with ?Gbind (-12.14kcal/mol) and Ki value (1.0nM), and ?Gbind (-12.41kcal/mol) and Ki value (0.4nM), respectively. Ligand 3 was shown to have the potential of dual acting serotonin/norepinephrine re-uptake inhibitor (SNRI) antidepressant activity in addition to opioid activities, and thus could be used for the design of multifunctional ligands in the area of a novel approach for the treatment of pain and depression. PMID:25703306

Mehr-Un-Nisa; Munawar, Munawar A; Lee, Yeon Sun; Rankin, David; Munir, Jawaria; Lai, Josephine; Khan, Misbahul A; Hruby, Victor J

2015-03-15

381

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

NASA Astrophysics Data System (ADS)

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

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

2014-03-01

382

Sequential catalytic role of bifunctional bicyclic guanidine in asymmetric phospha-Michael reaction.  

PubMed

The catalytic mechanism and origin of enantioselectivity of bicyclic guanidine-catalyzed phospha-Michael reaction between diphenyl phosphine oxide and ?-nitrostyrene were investigated by DFT calculations at M06-2X/cc-pVTZ//M06-2X/cc-pVDZ level in conjunction with the implicit SMD solvation method. The catalyst is found to be involved in all 3 steps of the proposed catalytic cycle, namely (1) tautomerization of phosphine oxide, (2) C-P bond formation and (3) concerted hydrogen transfer. The bifunctional role of the guanidine catalyst is clearly demonstrated in all 3 key steps. Due to the geometry of the bicyclic guanidine catalyst, the preferred orientation of the reactants in the transition state of enantioselective C-P bond forming step favours the R enantiomer, in excellent accord with the observed enantioselectivity. Analysis of various transition states suggests that the asymmetric C-P bond formation is controlled by the hydrogen bonding interaction and steric effect between the catalyst and substrate. Various weaker C-H···X (X = N, O and ?) interactions also play a role in stabilizing the key transition states. PMID:21509383

Cho, Bokun; Tan, Choon-Hong; Wong, Ming Wah

2011-06-21

383

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

PubMed

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

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

2014-06-01

384

Synthesis of an activated phosphonated bifunctional chelate with potential for PET imaging and radiotherapy.  

PubMed

The synthesis of a phosphonated acyclic bifunctional chelate L* for the labeling of biomaterial is described. L* is based on a pyridine backbone, functionalized in ortho positions by aminomethyl-bis-methylphosphonic acids, and, in the para position, by a side chain containing a reactive NHS carbamate function. The stability of L* in aqueous solutions at different pH values was studied by mass spectrometry, showing the activated function to be sensitive to hydrolysis above neutral pH. The reactivity of L* towards amine functions was tested using ethylamine under different conditions of pH and concentrations, and by the labeling of two reference peptides containing both an N-terminal amino function and a ?-amino group of a lysine residue in the backbone, and a supplementary thiol group of a cysteine residue for one of these two peptides. The results showed the coupling to be efficient at pH 8.0, with a total selectivity for the terminal amine function with respect to lysine and cysteine. The labeling was further performed on B28-13, a mouse monoclonal antibody specifically recognizing tenascin-C protein in human cancer. The labeled antibody was characterized by means of mass spectrometry and spectrofluorimetry, unraveling a labeling ratio of one chelate per antibody. Finally, the affinity of the labeled antibody towards its target was controlled by immunofluorescence staining experiments on human colon cancer biopsies, confirming the affinity of the labeled peptide for tenascin-C. PMID:23086384

Christine, Câline; Koubemba, Michaelle; Shakir, Shakir; Clavier, Séverine; Ehret-Sabatier, Laurence; Saupe, Falk; Orend, Gertraud; Charbonnière, Loïc J

2012-12-14

385

The determination of the rate of conjugation immunoglobuline with bifunctional chelator  

NASA Astrophysics Data System (ADS)

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

Málek, Z.; Miler, V.; Budský, F.

2006-01-01

386

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

PubMed

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

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

2013-11-01

387

Bifunctional Coupling Agents for Radiolabeling of Biomolecules and Target-Specific Delivery of Metallic Radionuclides  

PubMed Central

Receptor-based radiopharmaceuticals are of great current interest in early molecular imaging and radiotherapy of cancers, and provide a unique tool for target-specific delivery of radionuclides to the diseased tissues. In general, a target-specific radiopharmaceutical can be divided into four parts: targeting biomolecule (BM), pharmacokinetic modifying (PKM) linker, bifunctional coupling or chelating agent (BFC), and radionuclide. The targeting biomolecule serves as a “carrier” for specific delivery of the radionuclide. PKM linkers are used to modify radiotracer excretion kinetics. BFC is needed for radiolabeling of biomolecules with a metallic radionuclide. Different radiometals have significant difference in their coordination chemistry, and require BFCs with different donor atoms and chelator frameworks. Since the radiometal chelate can have a significant impact on physical and biological properties of the target-specific radiopharmaceutical, its excretion kinetics can be altered by modifying the coordination environment with various chelators or coligand, if needed. This review will focus on the design of BFCs and their coordination chemistry with technetium, copper, gallium, indium, yttrium and lanthanide radiometals. PMID:18538888

Liu, Shuang

2008-01-01

388

Assembly of cyanometalate-functionalized phosphotungstates with magnetic properties and bifunctional electrocatalytic activities.  

PubMed

Two cyanometalate-functionalized heteropolytungstates (C4H10ON)23[HN(CH2CH2OH)3]11H[Fe(III()CN)6(?2-P2W17O61Ni(II))4]·31H2O () and (C4H10ON)23[HN(CH2CH2OH)3]10H2[Fe(III)(CN)6(?2-P2W17O61Co(II))4]·27H2O () (C4H10ON = morpholine, HN(CH2CH2OH)3 = triethanol amine) have been successfully synthesized in aqueous solution under conventional reaction conditions, which demonstrated that it is a successful strategy to incorporate the cyanometalate fragment into lacunary heteropolytungstates. These polyanions were characterized by single-crystal X-ray diffraction, IR spectra, elemental analysis, thermogravimetric analysis, magnetic studies, and electrochemistry. Interestingly, the electrochemical studies have shown that the two complexes have bifunctional electrocatalytic activities towards not only the reduction of potassium iodate (KIO3) ascribed to the function of POM, but also the oxidation of the biological molecule ascorbic acid (AA) ascribed to the Fe-center in [M(II)4Fe(III)(CN)6](5+). Significantly, the magnetic investigations demonstrate the presence of ferromagnetic exchange interactions in (Ni4Fe) and antiferromagnetic interactions in (Co4Fe). PMID:25651792

Wang, Ya; Sun, Ming-Hui; Li, Feng-Yan; Sun, Zhi-Xia; Xu, Lin

2015-02-24

389

Herinase: a novel bi-functional fibrinolytic protease from the monkey head mushroom, Hericium erinaceum.  

PubMed

Herinase, a new bi-functional fibrinolytic metalloprotease, was purified from a medicinal and edible mushroom Hericium erinaceum. The enzyme was monomeric with a molecular mass of 51 kDa. Analysis of fibrin zymography showed an active band with a similar molecular mass. The N-terminal sequence of herinase VPSSFRTTITDAQLRG was highly distinguished from known fibrinolytic enzymes. Moreover, the enzyme activity was strongly inhibited by EDTA and EGTA, indicating that herinase is a metalloprotease. Herinase exhibited high specificity for the substrate t-PA followed by plasmin. The K(m) and V(max) values for H-D-Ile-Pro-Arg-PNA were found to be 4.7 mg and 26.7 U/ml respectively. Similarly, fibrin plate assays revealed that it was able to degrade fibrin clot directly and also able to activate plasminogen. Herinase provoked a rapid degradation of fibrin and fibrinogen ? chains and slower degradation of ? chains. It had no activity on the ? chains of fibrin and fibrinogen. This result suggests that herinase could possibly contain higher amount of ?-fibrinogenase. The activity of herinase was stimulated by metal ions such as Ca(2+), Mg(2+), and Mn(2+), but inhibited by Cu(2+), Fe(2+), and Zn(2+). Herinase exhibited maximum activity at 30 °C and pH 7.0. These results demonstrate that herinase could be a novel fibrinolytic enzyme. PMID:23564433

Choi, Bong-Suk; Sapkota, Kumar; Choi, Jun-Hui; Shin, Chang-ho; Kim, Seung; Kim, Sung-Jun

2013-06-01

390

Stability of the Mn photoluminescence in bifunctional ZnS:0.05Mn nanoparticles  

NASA Astrophysics Data System (ADS)

We investigate the stability of the orange band photoluminescence (PL) of bifunctional nanoparticles of Mn2+-doped ZnS at 5% (ZnS:0.05Mn). These 4-nm nanoparticles are synthesized via a one-step inorganic chemical route under ambient conditions. The phase, crystallinity, and morphology are analyzed via X-ray and electron diffractions and high-resolution electron microscopy. Based on the thermally activated carrier-transfer model, it is found that orange emission is rather stable at low temperatures and possesses thermal activation energy of ˜18 meV. The analysis of the PL decay curves suggests the coexistence of multiple lifetimes, that the shortening observed in PL lifetime is not due to the Mn2+ ions, and that the orange band decay is stable in temperature range from 10 K to 300 K. The measured M-H hysteresis loops demonstrate that ZnS:0.05Mn nanoparticles exhibit ferromagnetic ordering below 30 K, unlike its bulk counterpart. No magnetic field dependence of the Mn2+ PL intensity is observed up to 1 T. The stability of the PL signal when subject to an applied magnetic field is discussed. This study offers experimental evidence to test low-dimensional dilute magnetic semiconductor models and widens the range of applications of ZnS:Mn nanostructures beyond optoelectronics.

Beltran-Huarac, Juan; Wang, Jingzhou; Tanaka, Hiroki; Jadwisienczak, Wojciech M.; Weiner, Brad R.; Morell, Gerardo

2013-08-01

391

Preparation and characterization of bifunctional Ti-Fe kaolinite composite for Cr(VI) removal.  

PubMed

A novel bifunctional Ti-Fe kaolinite composite with excellent adsorption and photocatalytic properties was synthesized by a simple precipitation method. X-ray diffraction analysis and high-resolution transmission electron microscope analysis confirmed the existence of rutile phase TiO2 and amorphous iron in the composite. The specific surface area of the Ti-Fe kaolinite composite is 5.5 times higher than that of the original kaolinite. The composite was used as an adsorbent as well as photocatalyst for Cr(VI) removal. The results indicate that the low pH is favorable to the Cr(VI) removal by the composite and the removal rate of Cr(VI) reached 87% at pH 3.0. Visible light irradiation obviously increased the removal of Cr(VI) by the composite and greatly shortened reaction equilibrium time, which may be attributed to the photocatalytic reduction of Cr(VI) to Cr(III) by TiO2 associated with simultaneous redox cycle of Fe(III)/Fe(II). Various common co-existing ions did not show obvious effects on the removal of Cr(VI) by the composite. The composite exhibited very high stability for the Cr(VI) removal. The adsorption models and thermodynamics of Cr(VI) onto the composite were studied. PMID:25514646

Fida, Hussain; Guo, Sheng; Zhang, Gaoke

2015-03-15

392

Structure of a bifunctional alcohol dehydrogenase involved in bioethanol generation in Geobacillus thermoglucosidasius.  

PubMed

Bifunctional alcohol/aldehyde dehydrogenase (ADHE) enzymes are found within many fermentative microorganisms. They catalyse the conversion of an acyl-coenzyme A to an alcohol via an aldehyde intermediate; this is coupled to the oxidation of two NADH molecules to maintain the NAD(+) pool during fermentative metabolism. The structure of the alcohol dehydrogenase (ADH) domain of an ADHE protein from the ethanol-producing thermophile Geobacillus thermoglucosidasius has been determined to 2.5?Å resolution. This is the first structure to be reported for such a domain. In silico modelling has been carried out to generate a homology model of the aldehyde dehydrogenase domain, and this was subsequently docked with the ADH-domain structure to model the structure of the complete ADHE protein. This model suggests, for the first time, a structural mechanism for the formation of the large multimeric assemblies or `spirosomes' that are observed for this ADHE protein and which have previously been reported for ADHEs from other organisms. PMID:24100328

Extance, Jonathan; Crennell, Susan J; Eley, Kirstin; Cripps, Roger; Hough, David W; Danson, Michael J

2013-10-01

393

Synergistic effect resulting from combinations of a bifunctional HIV-1 antagonist with antiretroviral drugs.  

PubMed

Development of new anti-HIV therapeutics remains necessary for patients with HIV/AIDS who fail to respond to the current antiretroviral drugs. In this study, we investigated the potential cooperative effects of 2DLT, a bifunctional HIV-1 antagonist with viral inactivation and fusion inhibition activities, combined with different antiretroviral drugs, including HIV entry inhibitors, nucleoside and nonnucleoside reverse-transcriptase inhibitors (NRTIs and NNRTIs), and protease inhibitors. We found that combining 2DLT with these antiretroviral drugs resulted in synergism or strong synergism against infection by both X4 and R5 HIV-1 strains. Although 2DLT alone is highly effective against both NRTI- and NNRTI-resistant HIV-1 strains, combining 2DLT with zidovudine, stavudine, or nevirapine resulted in synergistic or strong synergistic antiviral effect against single or multiple RTI-resistant HIV-1 strains, suggesting that 2DLT can be further developed as a novel anti-HIV-1 drug for addition to the highly active antiretroviral therapy regimen for salvage therapy of patients with HIV/AIDS who are refractory to current antiretroviral drugs. PMID:24977378

Xu, Wei; Wang, Qian; Yu, Fei; Lu, Lu; Jiang, Shibo

2014-09-01

394

Bifunctional Lipocalin Ameliorates Murine Immune Complex-induced Acute Lung Injury  

PubMed Central

Molecules that simultaneously inhibit independent or co-dependent proinflammatory pathways may have advantages over conventional monotherapeutics. OmCI is a bifunctional protein derived from blood-feeding ticks that specifically prevents complement (C)-mediated C5 activation and also sequesters leukotriene B4 (LTB4) within an internal binding pocket. Here, we examined the effect of LTB4 binding on OmCI structure and function and investigated the relative importance of C-mediated C5 activation and LTB4 in a mouse model of immune complex-induced acute lung injury (IC-ALI). We describe two crystal structures of bacterially expressed OmCI: one binding a C16 fatty acid and the other binding LTB4 (C20). We show that the C5 and LTB4 binding activities of the molecule are independent of each other and that OmCI is a potent inhibitor of experimental IC-ALI, equally dependent on both C5 inhibition and LTB4 binding for full activity. The data highlight the importance of LTB4 in IC-ALI and activation of C5 by the complement pathway C5 convertase rather than by non-C proteases. The findings suggest that dual inhibition of C5 and LTB4 may be useful for treatment of human immune complex-dependent diseases. PMID:23625922

Roversi, Pietro; Ryffel, Bernhard; Togbe, Dieudonnée; Maillet, Isabelle; Teixeira, Mauro; Ahmat, Nurfilza; Paesen, Guido C.; Lissina, Olga; Boland, Wilhelm; Ploss, Kerstin; Caesar, Joseph J. E.; Leonhartsberger, Susanne; Lea, Susan M.; Nunn, Miles A.

2013-01-01

395

Bi-functional cross-linking reagents efficiently capture protein-DNA complexes in Drosophila embryos  

PubMed Central

Chromatin immunoprecipitation (ChIP) is widely used for mapping DNA-protein interactions across eukaryotic genomes in cells, tissues or even whole organisms. Critical to this procedure is the efficient cross-linking of chromatin-associated proteins to DNA sequences that are in close proximity. Since the mid-nineties formaldehyde fixation has been the method of choice. However, some protein-DNA complexes cannot be successfully captured for ChIP using formaldehyde. One such formaldehyde refractory complex is the developmentally regulated insulator factor, Elba. Here we describe a new embryo fixation procedure using the bi-functional cross-linking reagents DSG (disuccinimidyl glutarate) and DSP (dithiobis[succinimidyl propionate). We show that unlike standard formaldehyde fixation protocols, it is possible to capture Elba association with insulator elements in 2–5 h embryos using this new cross-linking procedure. We show that this new cross-linking procedure can also be applied to localize nuclear proteins that are amenable to ChIP using standard formaldehyde cross-linking protocols, and that in the cases tested the enrichment was generally superior to that achieved using formaldehyde cross-linking. PMID:24135698

Aoki, Tsutomu; Wolle, Daniel; Preger-Ben Noon, Ella; Dai, Qi; Lai, Eric C; Schedl, Paul

2014-01-01

396

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

PubMed

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

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

2014-08-01

397

Bifunctional (64)Cu-labelled macrobicyclic cage amine isothiocyanates for immuno-positron emission tomography.  

PubMed

New macrobicyclic cage amine or "sarcophagine" (sar) bifunctional chelators have been synthesised that form copper complexes of exceptional in vivo stability and incorporate isothiocyanate (-NCS) functional groups for conjugation to an antibody. The chelators were synthesised from the methyl-capped complex [Mg(II)(CH3)(NH2)sar](2+). Coordination of Mg(II) within the cavity of the cage amine ligand protects the secondary amine atoms from reacting with the -NCS functional groups. Two different [Mg(II)(NCS-sar)](2+) derivatives were conjugated to the HER2/neu-targeting antibody trastuzumab and the progress of the reaction monitored by electrospray mass spectrometry. The Mg(II) ion was removed from the immunoconjugates under mild conditions (0.1 M citrate buffer, pH 6). Labelling of the (CH3)(p-NCS-Ph)sar-trastuzumab conjugate with (64)Cu(II), a radioisotope suitable for positron emission tomography (PET), was fast (?5 min) and easily performed at room temperature with high radiochemical purity (>95%). Biodistribution and PET imaging studies in vivo showed that (64)Cu-labelled (CH3)(p-NCS-Ph)sar-trastuzumab maintained high stability under physiological conditions with high and selective uptake in a HER2-positive cancer cell line. The stability of the copper complex and the 12.7 h half-life of the radioisotope allows clear visualisation of tumours out to 48 h. PMID:25351329

Paterson, Brett M; Buncic, Gojko; McInnes, Lachlan E; Roselt, Peter; Cullinane, Carleen; Binns, David S; Jeffery, Charmaine M; Price, Roger I; Hicks, Rodney J; Donnelly, Paul S

2015-03-01

398

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

PubMed Central

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

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

2014-01-01

399

Directed assembly of bifunctional silica-iron oxide nanocomposite with open shell structure.  

PubMed

The synthesis of nanocomposite with controlled surface morphology plays a key role for pollutant removal from aqueous environments. The influence of the molecular size of the polyelectrolyte in synthesizing silica-iron oxide core-shell nanocomposite with open shell structure was investigated by using dynamic light scattering, atomic force microscopy, and quartz crystal microbalance with dissipation (QCM-D). Here, poly(diallydimethylammonium chloride) (PDDA) was used to promote the attachment of iron oxide nanoparticles (IONPs) onto the silica surface to assemble a nanocomposite with magnetic and catalytic bifunctionality. High molecular weight PDDA tended to adsorb on silica colloid, forming a more extended conformation layer than low molecular weight PDDA. Subsequent attachment of IONPs onto this extended PDDA layer was more randomly distributed, forming isolated islands with open space between them. By taking amoxicillin, an antibiotic commonly found in pharmaceutical waste, as the model system, better removal was observed for silica-iron oxide nanocomposite with a more extended open shell structure. PMID:25198872

Che, Hui Xin; Yeap, Swee Pin; Osman, Mohamed Syazwan; Ahmad, Abdul Latif; Lim, JitKang

2014-10-01

400

Bearing Strength of Lunar Soil  

Microsoft Academic Search

Bearing load vs penetration curves have been measured on a 1.3 g sample of lunar soil from the scoop of the Surveyor 3 soil mechanics surface sampler, using a circular indentor 2 mm in diameter. Measurements were made in an Earth laboratory, in air. This sample provided a unique opportunity to evaluate earlier, remotely controlled, in-situ measurements of lunar surface

L. D. Jaffe

1971-01-01

401

Bearing strength of lunar soil  

Microsoft Academic Search

Bearing load vs penetration curves have been measured on a 1.3 g sample of lunar soil from the scoop of the Surveyor 3 soil mechanics surface sampler, using a circular indentor 2 mm in diameter. Measurements were made in an Earth laboratory, in air. This sample provided a unique opportunity to evaluate earlier, remotely controlled, in-situ measurements of lunar surface

L. D. Jaffe

1971-01-01

402

Fuzzy control of magnetic bearings  

NASA Technical Reports Server (NTRS)

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.

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

1991-01-01

403

Tardigrades: Bears of the Moss  

NSDL National Science Digital Library

This online PowerPoint presentation is dedicated to the phylum Tardigrada. It discusses distinguishing characteristics of Tardigrades (also known as water bears), their relationship to arthropods and nematodes, internal structures, life stages, cryptobiosis, research opportunities, classification, identification, habitat, distribution, ease of study in the lab, and more. Each slide contains illustrations and descriptions of the microscopic animal.

William Miller

404

Intelligent Engine Systems: Bearing System  

NASA Technical Reports Server (NTRS)

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.

Singh, Arnant P.

2008-01-01

405

High performance rolling element bearing  

NASA Technical Reports Server (NTRS)

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.

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

406

Toxicity of Polar Bear Liver  

Microsoft Academic Search

ACCORDING to information from the Eskimos, and records from Arctic travellers, bad effects may follow the consumption, by men and dogs, of the livers of polar bear, bearded seal, Greenland fox and Eskimo huskies, whereas livers of other Arctic mammals can usually be eaten without injury.

Kaare Rodahl

1949-01-01

407

Gradient Tempering Of Bearing Races  

NASA Technical Reports Server (NTRS)

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.

Parr, Richardson A.

1991-01-01

408

Satellite monitoring of black bear.  

NASA Technical Reports Server (NTRS)

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.

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

1971-01-01

409

Synthesis of bifunctional molecules containing [12]aneN3 and coumarin moieties as effective DNA condensation agents and new non-viral gene vectors.  

PubMed

A series of bifunctional molecules with different combinations of macrocyclic polyamine [12]aneN3 and coumarin moieties, and , were synthesized by a two-step copper(i)-mediated alkyne-azide click reactions between 1,3,5-tris(azidomethyl)benzene and Boc-protected N-propynyl-[12]aneN3/7-propynyloxycoumarins. Agarose gel electrophoresis experiments indicated that bifunctional molecules and effectively induced complete plasmid DNA condensation at concentrations up to 40 ?M. It was found that the structural variation had a major impact on the condensation behavior of these compounds. The electrostatic interaction involving the [12]aneN3 moiety can be compensated by the binding contribution of the coumarin units during the DNA condensation process. These two types of interaction showed different effects on the reversibility of DNA condensation. Results from studies using dynamic laser scattering, atomic force microscopy, and EB replacement assay further supported the above conclusion. Cytotoxicity assays on bifunctional compounds and indicated their low cytotoxicity. Results from cellular uptake and cell transfection experiments proved that bifunctional compounds and successfully served as non-viral gene vectors. Furthermore, methyl substituents attached to the coumarin unit ( and ) greatly enhanced their DNA condensation capability and gene transfection. These bifunctional molecules, with the advantages of lower cytotoxicity, good water solubility, and potential structural modification, will have great potential for the development of new non-viral gene delivery agents. PMID:25772225

Yue, Pan; Zhang, Ying; Guo, Zhi-Fo; Cao, Ao-Cheng; Lu, Zhong-Lin; Zhai, Yong-Gong

2015-03-31

410

Hybrid bearings for turbopumps and the like  

NASA Technical Reports Server (NTRS)

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.

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

1994-01-01

411

Journal and Wave Bearing Impedance Calculation Software  

NASA Technical Reports Server (NTRS)

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.

Hanford, Amanda; Campbell, Robert

2012-01-01

412

Rubber bearings for precision positioning systems  

E-print Network

In this thesis we investigate the use of thin rubber sheets or laminates of metal and rubber sheets as bearings in precision positioning systems. Such bearings have the potential to replace more conventional flexures ...

Barton Martinelli, Augusto E

2005-01-01

413

A Preliminary Foil Gas Bearing Performance Map  

NASA Technical Reports Server (NTRS)

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.

DellaCorte, Christopher; Radil, Kevin C.; Bruckner, Robert J.; Howard, S. Adam

2006-01-01

414

Rolling Element Bearing Stiffness Matrix Determination (Presentation)  

SciTech Connect

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.

Guo, Y.; Parker, R.

2014-01-01

415

High Temperature, Permanent Magnet Biased Magnetic Bearings  

E-print Network

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

Gandhi, Varun R.

2010-07-14

416

Self-bearing motor design & control  

E-print Network

This thesis presents the design, implementation and control of a new class of self-bearing motors. The primary thesis contributions include the design and experimental demonstration of hysteresis self-bearing motors, novel ...

Imani Nejad, Mohammad

2013-01-01

417

Hunting for 'bears' in the backyard  

NSDL National Science Digital Library

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

Dave Walker

418

Stable isotopes to detect food-conditioned bears and to evaluate human-bear management  

USGS Publications Warehouse

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.

Hopkins, John B., III; Koch, Paul L.; Schwartz, Charles C.; Ferguson, Jake M.; Greenleaf, Schuyler S.; Kalinowski, Steven T.

2012-01-01

419

Effects of bearing deadbands on bearing loads and rotor stability  

NASA Technical Reports Server (NTRS)

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.

1984-01-01

420

Cartridge Bearing System for Space Applications  

NASA Technical Reports Server (NTRS)

Conventional spin axis ball bearings have been unreliable in spacecraft, often failing by two heretofore uncontrolled processes: ball retainer instability and lubricant breakdown. The Space Cartridge Bearing System (SCBS) addresses each of these mechanisms directly, leading to a bearing system with absolute freedom from retainer instability and negligible lubricant degradation rate. The result is a reliable plug-in bearing cartridge with a definite design life.

Kingsbury, Edward P.; Hanson, Robert A.; Jones, William R.; Mohr, Terry W.

1999-01-01

421

Mercury in polar bears from Alaska  

SciTech Connect

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.

Lentfer, J.W.; Galster, W.A.

1987-04-01

422

Predation of Svalbard reindeer by polar bears  

Microsoft Academic Search

Polar bears (Ursus maritimus) are believed to be obligate predators on marine mammals, and particularly, on two species of seals. This paper reports on\\u000a observations of polar bears preying (n=7) and scavenging (n=6) on Svalbard reindeer (Rangifer tarandus platyrhyncus). Similar to their closest evolutionary ancestor, the brown bear (U. arctos), polar bears are opportunistic and will prey on ungulates. Reindeer

Andrew E. Derocher; Øystein Wiig; Georg Bangjord

2000-01-01

423

Bifunctional Inhibition of Human Immunodeficiency Virus Type 1 Reverse Transcriptase: Mechanism and Proof-of-Concept as a Novel Therapeutic Design Strategy  

PubMed Central

Human immunodeficiency virus type 1 reverse transcriptase (HIV-1 RT) is a major target for currently approved anti-HIV drugs. These drugs are divided into two classes: nucleoside and non-nucleoside reverse transcriptase inhibitors (NRTIs and NNRTIs). This study illustrates the synthesis and biochemical evaluation of a novel bifunctional RT inhibitor utilizing d4T (NRTI) and a TMC-derivative (a diarylpyrimidine NNRTI) linked via a poly(ethylene glycol) (PEG) linker. HIV-1 RT successfully incorporates the triphosphate of d4T-4PEG-TMC bifunctional inhibitor in a base-specific manner. Moreover, this inhibitor demonstrates low nanomolar potency that has 4.3-fold and 4300-fold enhancement of polymerization inhibition in vitro relative to the parent TMC-derivative and d4T, respectively. This study serves as a proof-of-concept for the development and optimization of bifunctional RT inhibitors as potent inhibitors of HIV-1 viral replication. PMID:23659183

Bailey, Christopher M.; Sullivan, Todd J.; Iyidogan, Pinar; Tirado-Rives, Julian; Chung, Raymond; Ruiz-Caro, Juliana; Mohamed, Ebrahim; Jorgensen, William; Hunter, Roger; Anderson, Karen S.

2013-01-01

424

Hydrology of the Bear Lake Basin, Utah  

Microsoft Academic Search

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

Patsy Palacios; Chris Luecke; Justin Robinson

2007-01-01

425

14 CFR 23.623 - Bearing factors.  

Code of Federal Regulations, 2013 CFR

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

2013-01-01

426

14 CFR 23.623 - Bearing factors.  

Code of Federal Regulations, 2011 CFR

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

2011-01-01

427

14 CFR 27.623 - Bearing factors.  

Code of Federal Regulations, 2010 CFR

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

2010-01-01

428

14 CFR 29.623 - Bearing factors.  

Code of Federal Regulations, 2011 CFR

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

2011-01-01

429

14 CFR 29.623 - Bearing factors.  

Code of Federal Regulations, 2010 CFR

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

2010-01-01

430

14 CFR 27.623 - Bearing factors.  

Code of Federal Regulations, 2012 CFR

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

2012-01-01

431

14 CFR 25.623 - Bearing factors.  

Code of Federal Regulations, 2013 CFR

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

2013-01-01

432

14 CFR 29.623 - Bearing factors.  

Code of Federal Regulations, 2013 CFR

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

2013-01-01

433

14 CFR 25.623 - Bearing factors.  

Code of Federal Regulations, 2012 CFR

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

2012-01-01

434

14 CFR 23.623 - Bearing factors.  

Code of Federal Regulations, 2010 CFR

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

2010-01-01

435

14 CFR 25.623 - Bearing factors.  

Code of Federal Regulations, 2010 CFR

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

2010-01-01

436

14 CFR 25.623 - Bearing factors.  

Code of Federal Regulations, 2011 CFR

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

2011-01-01

437

14 CFR 27.623 - Bearing factors.  

Code of Federal Regulations, 2013 CFR

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

2013-01-01

438

14 CFR 23.623 - Bearing factors.  

Code of Federal Regulations, 2012 CFR

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

2012-01-01

439

14 CFR 29.623 - Bearing factors.  

Code of Federal Regulations, 2012 CFR

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

2012-01-01

440

14 CFR 27.623 - Bearing factors.  

Code of Federal Regulations, 2014 CFR

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

2014-01-01

441

14 CFR 23.623 - Bearing factors.  

Code of Federal Regulations, 2014 CFR

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

2014-01-01

442

14 CFR 25.623 - Bearing factors.  

Code of Federal Regulations, 2014 CFR

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

2014-01-01

443

14 CFR 29.623 - Bearing factors.  

Code of Federal Regulations, 2014 CFR

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

2014-01-01

444

14 CFR 27.623 - Bearing factors.  

Code of Federal Regulations, 2011 CFR

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

2011-01-01

445

Active magnetic bearings applied to industrial compressors  

Microsoft Academic Search

The design and shop test results are given for a high-speed eight-stage centrifugal compressor supported by active magnetic bearings. A brief summary of the basic operation of active magnetic bearings and the required rotor dynamics analysis are presented with specific attention given to design considerations for optimum rotor stability. The concerns for retrofits of magnetic bearings in existing machinery are

R. G. Kirk; J. F. Hustak; K. A. Schoeneck

1993-01-01

446

Cool Polar Bears: Dabbing on the Texture  

ERIC Educational Resources Information Center

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

O'Connell, Jean

2011-01-01

447

49 CFR 229.69 - Side bearings.  

Code of Federal Regulations, 2010 CFR

... Suspension System § 229.69 Side bearings. (a) Friction side bearings with springs designed to carry weight may not...than 25 percent of the springs in any one nest broken. (b) Friction side bearings may not be run in contact unless designed to...

2010-10-01

448

49 CFR 229.69 - Side bearings.  

Code of Federal Regulations, 2012 CFR

... Suspension System § 229.69 Side bearings. (a) Friction side bearings with springs designed to carry weight may not...than 25 percent of the springs in any one nest broken. (b) Friction side bearings may not be run in contact unless designed to...

2012-10-01

449

49 CFR 229.69 - Side bearings.  

Code of Federal Regulations, 2014 CFR

... Suspension System § 229.69 Side bearings. (a) Friction side bearings with springs designed to carry weight may not...than 25 percent of the springs in any one nest broken. (b) Friction side bearings may not be run in contact unless designed to...

2014-10-01

450

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

NASA Astrophysics Data System (ADS)

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

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

2015-02-01

451

Thin film superconductor magnetic bearings  

DOEpatents

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.

Weinberger, Bernard R. (Avon, CT)

1995-12-26

452

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

PubMed Central

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

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

2009-01-01

453

Structural basis for hypermodification of the wobble uridine in tRNA by bifunctional enzyme MnmC  

PubMed Central

Background Methylaminomethyl modification of uridine or 2-thiouridine (mnm5U34 or mnm5s2U34) at the wobble position of tRNAs specific for glutamate, lysine and arginine are observed in Escherichia coli and allow for specific recognition of codons ending in A or G. In the biosynthetic pathway responsible for this post-transcriptional modification, the bifunctional enzyme MnmC catalyzes the conversion of its hypermodified substrate carboxymethylaminomethyl uridine (cmnm5U34) to mnm5U34. MnmC catalyzes the flavin adenine dinucleotide (FAD)-dependent oxidative cleavage of carboxymethyl group from cmnm5U34 via an imine intermediate to generate aminomethyl uridine (nm5U34), which is subsequently methylated by S-adenosyl-L-methionine (SAM) to yield methylaminomethyl uridine (mnm5U34). Results The X-ray crystal structures of SAM/FAD-bound bifunctional MnmC from Escherichia coli and Yersinia pestis, and FAD-bound bifunctional MnmC from Yersinia pestis were determined and the catalytic functions verified in an in vitro assay. Conclusion The crystal structures of MnmC from two Gram negative bacteria reveal the overall architecture of the enzyme and the relative disposition of the two independent catalytic domains: a Rossmann-fold domain containing the SAM binding site and an FAD containing domain structurally homologous to glycine oxidase from Bacillus subtilis. The structures of MnmC also reveal the detailed atomic interactions at the interdomain interface and provide spatial restraints relevant to the overall catalytic mechanism. PMID:23617613

2013-01-01

454

Rolling element bearings in space  

NASA Technical Reports Server (NTRS)

Some of the advances in tribology that have been associated with aerospace mechanisms are discussed. The needs of aerospace have been the dominant forces leading to improvements in understanding and applying tribology technology. In the past two decades improvements in understanding bearing torque, elastohydrodynamic lubrication, lubricant distribution, cage stability, and transfer film lubricants have been made. It is anticipated that further developments will be made in response to future aerospace requirements.

Kannel, J. W.; Dufrane, K. F.

1986-01-01

455

Bearing capacity of desiccated tailings  

Microsoft Academic Search

The development of matric suctions in soils contributes to their shear strength, resulting in an enhanced factor of safety against bearing-capacity failure. In this paper, matric suction profiles of desiccated mine tailings are predicted from a steady-state solution for evaporative conditions, and from an isothermal mathematical model that simulates liquid and vapor water flow through soils. The shear-strength envelope with

Daud W. Rassam; David J. Williams

1999-01-01

456

DNA modifications by a novel bifunctional trinuclear platinum phase I anticancer agent.  

PubMed

The DNA-binding profile of a novel, trinuclear platinum Phase I clinical agent (BBR3464) is summarized. The structure of BBR3464 is best described as two trans-[PtCl(NH3)2] units linked by a tetra-amine [trans-Pt(NH3)2{H2N(CH2)6NH2}2]2+ unit. The +4 charge of BBR3464, the presence of at least two Pt coordination units capable of binding to DNA, and the consequences of such DNA binding are remarkable departures from the cisplatin structural paradigm. The chemical and biological features argue that the drug should be considered the first clinical representative of an entirely new structural class of DNA-modifying anticancer agents. The high charge on BBR3464 facilitates rapid binding to DNA with a t1/2 of approximately 40 min, significantly faster than the neutral cisplatin. The melting temperature of DNA adducted by BBR3464 increased at low ionic strength but decreased in high salt for the same rb. This unusual behavior is in contrast to that of cisplatin. BBR3464 produces an unwinding angle of 14 degrees in negatively supercoiled pSP73 plasmid DNA, indicative of bifunctional DNA binding. Quantitation of interstrand DNA-DNA cross-linking in plasmid pSP73 DNA linearized by EcoRI indicated approximately 20% of the DNA to be interstrand cross-linked. While this is significantly higher than the value for cisplatin, it is, interestingly, lower than that for dinuclear platinum compounds such as [{trans-PtCl(NH3)2}2H2N(CH2)6NH2]2+ (BBR3005) where interstrand cross-linking efficiency may be as high as 70-90%. Either the presence of charge in the linker backbone or the increased distance between platinating moieties may contribute to this relatively decreased ability of BBR3464 to induce DNA interstrand cross-linking. Fluorescence experiments with ethidium bromide were consistent with the formation of long-range delocalized lesions on DNA produced by BBR3464. The sequence preference for BBR3464 on plasmid DNA was determined to the exact base pair by assaying extension of the polynucleotide by VentR(exo+) DNA polymerase. Strong sequence preference for single dG or d(GG) sites was suggested. The presence of relatively few blocks on DNA in comparison to either cisplatin or BBR3005 was indicative of high sequence selectivity. The following appropriate sequence where stop sites occur was chosen: [sequence: see text] molecular modeling on 1,4 interstrand (G'30 to G33) and 1,5 intrastrand (G33 to G29) cross-links further confirmed the similarity in energy between the two forms of cross-link. Finally, immunochemical analysis confirmed the unique nature of the DNA adducts formed by BBR3464. This analysis showed that antibodies raised to cisplatin-adducted DNA did not recognize DNA modified by BBR3464. In contrast, DNA modified by BBR3464 inhibited the binding of antibodies raised to transplatin-adducted DNA. Thus, the bifunctional binding of BBR3464 contains few similarities to that of cisplatin but may have a subset of adducts recognized as being similar to the transplatinum species. In summary, the results point to a unique profile of DNA binding for BBR3464, strengthening the original hypothesis that modification of DNA binding in manners distinct from that of cisplatin will also lead to a distinct and unique profile of antitumor activity. PMID:10346899

Brabec, V; Kaspárková, J; Vrána, O; Nováková, O; Cox, J W; Qu, Y; Farrell, N

1999-05-25

457

Selective Bifunctional Modification of a Non-catenated Metal-Organic Framework Material via 'Click' Chemistry  

SciTech Connect

A noncatenated, Zn-based metal-organic framework (MOF) material bearing silyl-protected acetylenes was constructed and postsynthetically modified using 'click' chemistry. Using a solvent-based, selective deprotection strategy, two different organic azides were 'clicked' onto the MOF crystals, resulting in a porous material whose internal and external surfaces are differently functionalized.

Gadzikwa, Tendai; Farha, Omar K.; Malliakas, Christos D.; Kanatzidis, Mercouri G.; Hupp, Joseph T.; Nguyen, SonBinh T.; NWU

2009-12-01

458

Bearing strength of lunar soil.  

NASA Technical Reports Server (NTRS)

Bearing load vs penetration curves have been measured on a 1.3 g sample of lunar soil from the scoop of the Surveyor 3 soil mechanics surface sampler, using a circular indentor 2 mm in diameter. Measurements were made in an Earth laboratory, in air. This sample provided a unique opportunity to evaluate earlier, remotely controlled, in-situ measurements of lunar surface bearing properties. Bearing capacity, measured at a penetration equal to the indentor diameter, varied from 0.02-0.04 N/sq cm at bulk densities of 1.15 g/cu cm to 30-100 N/sq cm at 1.9 g/cu cm. Deformation was by compression directly below the indentor at bulk densities below 1.61 g/cu cm, by outward displacement at bulk densities over 1.62 g/cu cm. Preliminary comparison of in-situ remote measurements with those on returned material indicates good agreement if the lunar regolith at Surveyor 3 has a bulk density of 1.6 g/cu cm at 2.5 cm depth.

Jaffe, L. D.

1971-01-01

459

Fault Tolerant Homopolar Magnetic Bearings  

NASA Technical Reports Server (NTRS)

Magnetic suspensions (MS) satisfy the long life and low loss conditions demanded by satellite and ISS based flywheels used for Energy Storage and Attitude Control (ACESE) service. This paper summarizes the development of a novel MS that improves reliability via fault tolerant operation. Specifically, flux coupling between poles of a homopolar magnetic bearing is shown to deliver desired forces even after termination of coil currents to a subset of failed poles . Linear, coordinate decoupled force-voltage relations are also maintained before and after failure by bias linearization. Current distribution matrices (CDM) which adjust the currents and fluxes following a pole set failure are determined for many faulted pole combinations. The CDM s and the system responses are obtained utilizing 1D magnetic circuit models with fringe and leakage factors derived from detailed, 3D, finite element field models. Reliability results are presented vs. detection/correction delay time and individual power amplifier reliability for 4, 6, and 7 pole configurations. Reliability is shown for two success criteria, i.e. (a) no catcher bearing contact following pole failures and (b) re-levitation off of the catcher bearings following pole failures. An advantage of the method presented over other redundant operation approaches is a significantly reduced requirement for backup hardware such as additional actuators or power amplifiers.

Li, Ming-Hsiu; Palazzolo, Alan; Kenny, Andrew; Provenza, Andrew; Beach, Raymond; Kascak, Albert

2003-01-01

460

SLEEPLESS is a bi-functional regulator of excitability and cholinergic synaptic transmission  

PubMed Central

Summary Background Although sleep is conserved throughout evolution, the molecular basis of its control is still largely a mystery. We previously showed that the quiver/sleepless (qvr/sss) gene encodes a membrane-tethered protein that is required for normal sleep in Drosophila. SLEEPLESS (SSS) protein functions, at least in part, by upregulating the levels and open probability of Shaker (Sh) potassium channels to suppress neuronal excitability and enable sleep. Consistent with this proposed mechanism, loss-of-function mutations in Sh phenocopy qvr/sss null mutants. However, sleep is more genetically modifiable in Sh than in qvr/sss mutants, suggesting that sss may regulate additional molecules to influence sleep. Results Here we show that SSS also antagonizes nicotinic acetylcholine receptors (nAChRs) to reduce synaptic transmission and promote sleep. Mimicking this antagonism with the nAChR inhibitor mecamylamine or by RNAi knockdown of specific nAChR subunits is sufficient to restore sleep to qvr/sss mutants. Regulation of nAChR activity by SSS occurs post-transcriptionally since the levels of nAChR mRNAs are unchanged in qvr/sss mutants. Regulation of nAChR activity by SSS may in fact be direct, since SSS forms a stable complex with and antagonizes fly nAChR function in transfected cells. Intriguingly, lynx1, a mammalian homolog of SSS, can partially restore normal sleep to qvr/sss mutants, and lynx1 can form stable complexes with Shaker-type channels and nAChRs. Conclusions Together, our data point to an evolutionarily conserved, bi-functional role for SSS and its homologs in controlling excitability and synaptic transmission in fundamental processes of the nervous system such as sleep. PMID:24613312

Wu, Meilin; Robinson, James E.; Joiner, William J.

2014-01-01

461

Isomerism in Benzyl-DOTA Derived Bifunctional Chelators: Implications for Molecular Imaging.  

PubMed

The bifunctional chelator IB-DOTA has found use in a range of biomedical applications given its ability to chelate many metal ions, but in particular the lanthanide(III) ions. Gd(3+) in particular is of interest in the development of new molecular imaging agents for MRI and is highly suitable for chelation by IB-DOTA. Given the long-term instability of the aryl isothiocyanate functional group we have used the more stable nitro derivative (NB-DOTA) to conduct a follow-up study of some of our previous work on the coordination chemistry of chelates of these BFCs. Using a combination of NMR and HPLC to study the Eu(3+) and Yb(3+) chelates of NB-DOTA, we have demonstrated that this ligand will produce two discrete regioisomeric chelates at the point at which the metal ion is introduced into the BFC. These regioisomers are defined by the position of the benzylic substituent on the macrocyclic ring: adopting an equatorial position either at the corner or the side of the [3333] ring conformation. These regioisomers are incapable of interconversion and are distinct, separate structures with different SAP/TSAP ratios. The side isomer exhibits an increased population of the TSAP isomer, pointing to more rapid water exchange kinetics in this regioisomer. This has potential ramifications for the use of these two regioisomers of Gd(3+)-BFC chelates in MRI applications. We have also found that, remarkably, there is little or no freedom of rotation about the first single bond extending from the macrocyclic ring to the benzylic substituent. Since this is the linkage through which the chelate is conjugated to the remainder of the molecular imaging probe, this result implies that there may be reduced local rotation of the Gd(3+) chelate within a molecular imaging probe. This implies that this type of BFC could exhibit higher relaxivities than other types of BFC. PMID:25635382

Payne, Katherine M; Woods, Mark

2015-02-18

462

Radiochemical studies of 99mTc complexes of modified cysteine ligands and bifunctional chelating agents.  

PubMed

The synthesis of four novel ligands using the amino-acid cysteine and its ethyl carboxylate derivative is described. The synthetic method involves a two-step procedure, wherein the intermediate Schiff base formed by the condensation of the amino group of the cysteine substrate and salicylaldehyde is reduced to give the target ligands. The intermediates and the final products were characterized by high resolution nuclear magnetic resonance spectroscopy. Complexation studies of the ligands with 99mTc were optimized using stannous tartrate as the reducing agent under varying reaction conditions. The complexes were characterized using standard quality control techniques such as thin layer chromatography, paper electrophoresis, and paper chromatography. Lipophilicities of the complexes were estimated by solvent extraction into chloroform. Substantial changes in net charge and lipophilicity of the 99mTc complexes were observed on substituting the carboxylic acid functionality in ligands I and II with the ethyl carboxylate groups (ligands II and IV). All the ligands formed 99mTc complexes in high yield. Whereas the complexes with ligands I and II were observed to be hydrophilic in nature and not extractable into CHCl3, ligands III and IV resulted in neutral and lipophilic 99mTc complexes. The 99mTc complex with ligand II was not stable and on storage formed a hydrophilic and nonextractable species. The biodistribution of the complexes of ligands I and II showed that they cleared predominantly through the kidneys, whereas the complexes with ligands III and IV were excreted primarily through the hepatobiliary system. No significant brain uptake was observed with the 99mTc complexes with ligands III and IV despite their favorable properties of neutrality, lipophilicity, and conversion into a hydrophilic species. These ligands offer potential for use as bifunctional chelating agents. PMID:10473195

Pillai, M R; Kothari, K; Banerjee, S; Samuel, G; Suresh, M; Sarma, H D; Jurisson, S

1999-07-01

463

Activation of Aurora-A kinase by protein phosphatase inhibitor-2, a bifunctional signaling protein.  

PubMed

Aurora-A kinase is necessary for centrosome maturation, for assembly and maintenance of a bipolar spindle, and for proper chromosome segregation during cell division. Aurora-A is an oncogene that is overexpressed in multiple human cancers. Regulation of kinase activity apparently depends on phosphorylation of Thr-288 in the T-loop. In addition, interactions with targeting protein for Xenopus kinesin-like protein 2 (TPX2) allosterically activate Aurora-A. The Thr-288 phosphorylation is reversed by type-1 protein phosphatase (PP1). Mutations in the yeast Aurora, Ipl1, are suppressed by overexpression of Glc8, the yeast homolog of phosphatase inhibitor-2 (I-2). In this study, we show that human I-2 directly and specifically stimulated recombinant human Aurora-A activity in vitro. The I-2 increase in kinase activity was not simply due to inhibition of PP1 because it was not mimicked by other phosphatase inhibitors. Furthermore, activation of Aurora-A was unaffected by deletion of the I-2 N-terminal PP1 binding motif but was eliminated by deletion of the I-2 C-terminal domain. Aurora-A and I-2 were recovered together from mitotic HeLa cells. Kinase activation by I-2 and TPX2 was not additive and occurred without a corresponding increase in T-loop phosphorylation. These results suggest that both I-2 and TPX2 function as allosteric activators of Aurora-A. This implies that I-2 is a bifunctional signaling protein with separate domains to inhibit PP1 and directly stimulate Aurora-A kinase. PMID:15173575

Satinover, David L; Leach, Craig A; Stukenberg, P Todd; Brautigan, David L

2004-06-01

464

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

PubMed

Unusual N-acetylated sugars have been observed on the O-antigens of some Gram-negative bacteria and on the S-layers of both Gram-positive and Gram-negative bacteria. One such sugar is 3-aceta