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1

Synthesis and characterization of diblock copolymer by enzymatic ring-opening polymerization and ATRP from a novel bifunctional initiator  

Microsoft Academic Search

A new method is reported for synthesizing AB-type diblock copolymer polycaprolactone-block-polystyrene (PCL-b-PSt) from a novel bifunctional initiator 2.2.2-trichloroethanol (TCE) by combining two different polymerization techniques: enzymatic ring-opening polymerization (ROP) and atom transfer radical polymerization (ATRP). Trichloromethyl terminated PCL was prepared by enzymatic ROP of ?-caprolactone (?-CL) in the presence of Novozyme-435 and TCE as biocatalyst and initiator, respectively, and subsequently

Ke Sha; Dongshuang Li; Shuwei Wang; Lu Qin; Jingyuan Wang

2005-01-01

2

Bearings.  

National Technical Information Service (NTIS)

The bibliography is a collection of references on bearings. The references are sequenced numerically within the following topics: 1. Airframe Bearings, 2. Ball Bearings, 3. Roller Bearings, 4. Antifriction Bearings, 5. Gas Bearings, 6. Journal Bearings. 7...

1973-01-01

3

BEARS: A radioactive ion beam initiative at LBNL  

SciTech Connect

BEARS is an initiative to develop a radioactive ion-beam capability at Lawrence Berkeley National Laboratory. The aim is to produce isotopes at an existing medical cyclotron and to accelerate them at the 88{sup {double_prime}} Cyclotron. To overcome the 300-meter physical separation of these two accelerators, a carrier-gas transport system will be used. At the terminus of the capillary, the carrier gas will be separated and the isotopes will be injected into the 88{sup {double_prime}} Cyclotron{close_quote}s Advanced Electron Cyclotron Resonance ion source. The first radioactive beams to be developed will include 20-min {sup 11}C and 70-sec {sup 14}O, produced by (p, n) and (p, {alpha}) reactions on low-Z targets. Tests at the 88{sup {double_prime}} Cyclotron lead to projections of initial {sup 11}C beams of 2{times}10{sup 8}&hthinsp;ions/sec {sup 14}O beams of 1{times}10{sup 6}&hthinsp;ions/sec. Construction of BEARS is expected to be completed in the spring of 1999. {copyright} {ital 1999 American Institute of Physics.}

Powell, J.; Guo, F.Q.; Joosten, R.; Larimer, R.-M.; Lyneis, C.M.; McMahan, P.; Moltz, D.M.; Norman, E.B.; O`Neil, J.P.; Rowe, M.W.; VanBrocklin, H.F.; Wutte, D.; Xie, Z.Q.; Xu, X.J.; Cerny, J. [Lawrence Berkeley National Laboratory, University of California, Berkeley, California 94720 (United States)] Haustein, P.E. [Chemistry Department, Brookhaven National Laboratory, Upton, New York 11973 (United States)

1999-06-01

4

BEARS: A radioactive ion beam initiative at LBNL  

SciTech Connect

BEARS is an initiative to develop a radioactive ion-beam capability at Lawrence Berkeley National Laboratory. The aim is to produce isotopes at an existing medical cyclotron and to accelerate them at the 88'' Cyclotron. To overcome the 300-meter physical separation of these two accelerators, a carrier-gas transport system will be used. At the terminus of the capillary, the carrier gas will be separated and the isotopes will be injected into the 88'' Cyclotron's Advanced Electron Cyclotron Resonance ion source. The first radioactive beams to be developed will include 20-min {sup 11}C and 70-sec {sup 14}O, produced by (p, n) and (p, {alpha}) reactions on low-Z targets. Tests at the 88'' Cyclotron lead to projections of initial {sup 11}C beams of 2x10{sup 8} ions/sec {sup 14}O beams of 1x10{sup 6} ions/sec. Construction of BEARS is expected to be completed in the spring of 1999.

Powell, J.; Guo, F. Q.; Joosten, R.; Larimer, R.-M.; Lyneis, C. M.; McMahan, P.; Moltz, D. M.; Norman, E. B.; O'Neil, J. P.; Rowe, M. W.; VanBrocklin, H. F.; Wutte, D.; Xie, Z. Q.; Xu, X. J.; Cerny, Joseph [Lawrence Berkeley National Laboratory, University of California, Berkeley, California 94720 (United States); Haustein, P. E. [Chemistry Department, Brookhaven National Laboratory, Upton, New York 11973 (United States)

1999-06-10

5

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

Federal Register 2010, 2011, 2012, 2013

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

2010-01-21

6

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 ...

Bledsoe, Miss

2011-04-07

7

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

Microsoft Academic Search

Numerical experiments are conducted using an idealized cloud-resolving model to explore the sensitivity of deep convective initiation (DCI) to the lapse rate of the active cloud-bearing layer (ACBL; the atmo- spheric layer above the level of free convection (LFC)). Clouds are initiated using a new technique that involves a preexisting airmass boundary initialized such that the (unrealistic) adjustment of the

Adam L. Houston; Dev Niyogi

2007-01-01

8

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

Federal Register 2010, 2011, 2012, 2013

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

2012-11-08

9

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

Federal Register 2010, 2011, 2012, 2013

...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

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

11

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

PubMed

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

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

1993-08-01

12

Initial non-weight-bearing therapy is important for preventing vertebral body collapse in elderly patients with clinical vertebral fractures  

PubMed Central

Purpose The aim of the present conventional observational study was to compare the clinical outcomes of initial non-weight-bearing therapy and conventional relative rest therapy among elderly patients with clinical vertebral fractures. Methods In total, 196 consecutive patients with clinical vertebral fractures (mean age: 78 years) who were hospitalized for treatment between January 1999 and March 2007 were analyzed. Initial non-weight-bearing therapy consisted of complete bed rest allowing rolling on the bed without any weight-bearing to the spine for 2 weeks, followed by rehabilitation wearing a soft brace. The indications for initial non-weight-bearing therapy were vertebral fracture involving the posterior portion of the vertebral body at the thoraco-lumbar spine, mild neurological deficit, instability of the fracture site, severe pain, multiple vertebral fractures arising from trauma, malalignment at the fracture site, and mild spinal canal stenosis caused by the fracture. Patients who met the indication criteria were treated with initial non-weight-bearing therapy (n = 103), while the other patients were treated with conventional relative rest (n = 93). All the patients were uniformly treated with intramuscular elcatonin to relieve pain. The primary endpoint was progression of the vertebral fracture. The secondary endpoints included bony union and subjective back pain. The follow-up period was 12 weeks. Results Compared with the conventional relative rest group, the collapse rate of the anterior and posterior portions of the vertebral body was significantly smaller in the initial non-weight-bearing group. The bony union rate was 100% in the initial non-weight-bearing group and 97% in the conventional relative rest group. The number of patients who experienced back pain was significantly lower in the initial non-weight-bearing group than in the conventional relative rest group. Conclusion These results suggest that initial non-weight-bearing therapy is important for preventing vertebral body collapse and for relieving pain among elderly patients with clinical vertebral fractures.

Kishikawa, Yoichi

2012-01-01

13

Conformal load-bearing antenna structures (CLAS): initiative for multiple military and commercial applications  

NASA Astrophysics Data System (ADS)

The Structures Division of the Air Force's Wright Laboratory is sponsoring the development and demonstration of a new high pay-off technology termed CLAS--Conformal Load Bearing Antenna Structures. Northrop Grumman Corporation and TRW/ASD are developing the technology under the `Smart-Skin Structure Technology Demonstration (S3D)' program, contract, No. F33615-93-C-3200. The program goal is to design, develop, fabricate, and test a CLAS component and lay the foundation for future work where potential benefits from structurally integrated antennas may be realized. Key issues will focus but are not limited to the design, structures, and manufacturing aspects of antenna embedment into load bearing aircraft structures. Results from Phase 1 of the program have been previously reported, where initial pay-offs in reducing overall airframe acquisition and support cost, weight, signature, and drag were quantitatively and qualitatively identified. A full-sized CLAS component, featuring a broadband multi-arm spiral embedded in sandwich stiffened structure, will be fabricated and tested for static strength, durability, and damage tolerance. Basic electrical performance, (e.g., radiation patterns, gain, and impedance) will also be verified; however, extensive electrical validation will be the subject of further work. Key aspects of the work and progress to date are detailed below. Also covered are future projections of CLAS technology expansion beyond tactical aircraft into other military products highlighting ships, army vehicles, and `spin-off' commercial applications to civil aircraft and the automotive industry.

Lockyer, Allen J.; Alt, Kevin H.; Kudva, Jayanth N.; Kinslow, Robert W.; Goetz, Allen C.

1997-06-01

14

Tight bifunctional hierarchical catalyst.  

PubMed

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

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

2011-11-03

15

Amplification of a plasmid bearing a mammalian replication initiation region in chromosomal and extrachromosomal contexts  

PubMed Central

Amplified genes in cancer cells reside on extrachromosomal double minutes (DMs) or chromosomal homogeneously staining regions (HSRs). We used a plasmid bearing a mammalian replication initiation region to model gene amplification. Recombination junctions in the amplified region were comprehensively identified and sequenced. The junctions consisted of truncated direct repeats (type 1) or inverted repeats (type 2) with or without spacing. All of these junctions were frequently detected in HSRs, whereas there were few type 1 or a unique type 2 flanked by a short inverted repeat in DMs. The junction sequences suggested a model in which the inverted repeats were generated by sister chromatid fusion. We were consistently able to detect anaphase chromatin bridges connected by the plasmid repeat, which were severed in the middle during mitosis. De novo HSR generation was observed in live cells, and each HSR was lengthened more rapidly than expected from the classical breakage/fusion/bridge model. Importantly, we found massive DNA synthesis at the broken anaphase bridge during the G1 to S phase, which could explain the rapid lengthening of the HSR. This mechanism may not operate in acentric DMs, where most of the junctions are eliminated and only those junctions produced through stable intermediates remain.

Harada, Seiyu; Sekiguchi, Naoki; Shimizu, Noriaki

2011-01-01

16

Amplification of a plasmid bearing a mammalian replication initiation region in chromosomal and extrachromosomal contexts.  

PubMed

Amplified genes in cancer cells reside on extrachromosomal double minutes (DMs) or chromosomal homogeneously staining regions (HSRs). We used a plasmid bearing a mammalian replication initiation region to model gene amplification. Recombination junctions in the amplified region were comprehensively identified and sequenced. The junctions consisted of truncated direct repeats (type 1) or inverted repeats (type 2) with or without spacing. All of these junctions were frequently detected in HSRs, whereas there were few type 1 or a unique type 2 flanked by a short inverted repeat in DMs. The junction sequences suggested a model in which the inverted repeats were generated by sister chromatid fusion. We were consistently able to detect anaphase chromatin bridges connected by the plasmid repeat, which were severed in the middle during mitosis. De novo HSR generation was observed in live cells, and each HSR was lengthened more rapidly than expected from the classical breakage/fusion/bridge model. Importantly, we found massive DNA synthesis at the broken anaphase bridge during the G1 to S phase, which could explain the rapid lengthening of the HSR. This mechanism may not operate in acentric DMs, where most of the junctions are eliminated and only those junctions produced through stable intermediates remain. PMID:20929873

Harada, Seiyu; Sekiguchi, Naoki; Shimizu, Noriaki

2010-10-06

17

Bifunctional oxygen electrodes  

Microsoft Academic Search

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

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

1985-01-01

18

Upright, weight-bearing, dynamic–kinetic MRI of the spine: initial results  

Microsoft Academic Search

The potential relative beneficial aspects of upright, weight-bearing (pMRI), dynamic–kinetic (kMRI) spinal imaging over that of recumbent MRI (rMRI) include the revelation of occult spinal disease dependent on true axial loading, the unmasking of kinetic-dependent spinal disease and the ability to scan the patient in the position of clinically relevant signs and symptoms. This imaging unit under study also demonstrated

J. Randy Jinkins; Jay S. Dworkin; Raymond V. Damadian

2005-01-01

19

Bifunctional oxygen electrodes  

NASA Astrophysics Data System (ADS)

The objective of the research on bifunctional oxygen electrodes for alkaline electrolytes was to improve significantly both the cathodic and anodic polarization as well as the cycle life of such electrodes. The research has focused on finding high-efficiency, long-life electrocatalysts for O2 reduction and generation and achieving an understanding of the mechanisms of the catalysis. Catalyst systems which have been examined in alkaline electrolytes have included the following:various types of carbons and graphites; chemically-modified carbons and graphites using adsorptive attachment (e.g., various quinones, macrocycles and chemical linkages); silver and various intermetallics; various oxide systems including perovskites, spinels, pyrochlores and other mixed transition metal oxides; transition metal macrocycles including porphyrins, phthalocyanines, naphthalocyanines and tetraazaannulenes; and thermally-treated macrocycles. Mechanistic studies have particularly focused on the reduction of O2 on various carbon/graphite surfaces and the role of the O2(-) radical ion.

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

1985-01-01

20

Bifunctional Oxygen Electrodes. Final Report.  

National Technical Information Service (NTIS)

Objective of the research on bifunctional oxygen electrodes for alkaline electrolytes has been to improve significantly both the cathodic and anodic polarization as well as the cycle life of such electrodes. The research has focused on finding high-effici...

D. Tryk W. Aldred Z. Chen C. Fierro J. Hashiguchi

1985-01-01

21

Initial observations of mesospheric winds using IDI Radar measurements at the Bear Lake Observatory  

NASA Astrophysics Data System (ADS)

The adaptation of Imaging Doppler Interferometry (IDI) to the dynasonde deployed at the Bear Lake Observatory (41.9°N, 111.4°W) in northeastern Utah enables the routine measurement of mesospheric dynamics. Influenced by the direction of the prevailing wind, a clear seasonal variation is seen in the mesospheric echo numbers. The technique also provides a monitor for the amplitude of the main tidal modes as well as for studying planetary waves with periods of several days. The observations are found to be consistent with those from different instruments based at the same site thus confirming the IDI characterisation of the mesospheric wind field.

Berkey, F. T.; Fish, C. S.; Jones, G. O. L.

22

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

Federal Register 2010, 2011, 2012, 2013

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

2013-08-19

23

Bifunctional oxygen electrodes. Final report  

Microsoft Academic Search

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

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

1985-01-01

24

Synthesis and evaluation of a macrocyclic bifunctional chelating agent for use with bismuth radionuclides.  

PubMed

The detailed synthesis of the bifunctional chelating agent 2-(p-isothiocyanatobenzyl)-1,4,7,10,13-pentaazacyclopentadecane-N,N',N",N"',N"-pentaacetic acid (BF_PEPA) is reported. This ligand was conjugated to monoclonal antibody B3 and the resultant immunoconjugate radiolabeled with (205,206)Bi. The in vivo stability of the radiolabeled immunoconjugate, and targeting characteristics were determined by biodistribution studies in A431 xenograft tumor-bearing mice sacrificed at 0.5, 1, 2, 4, and 24 hr. Results indicate that BF_PEPA appears to not be a suitable bifunctional chelating agent for sequestering isotopes of Bi(III) for radioimmunotherapy applications. PMID:11395314

Garmestani, K; Yao, Z; Zhang, M; Wong, K; Park, C W; Pastan, I; Carrasquillo, J A; Brechbiel, M W

2001-05-01

25

Bifunctional chromophore for photorefractive applications  

Microsoft Academic Search

A bifunctional chromophore has been developed which serves as a charge transporting agent as well as a second-order nonlinear optical compound. The chromophore has been incorporated into an inert polymer to form a photorefractive material when doped with a photocharge generation sensitizer. The dependence of the four-wave mixing diffraction efficiency, holographic grating writing rate, and two-beam coupling gain on the

Yue Zhang; Saswati Ghosal; Martin K. Casstevens; Ryszard Burzynski

1995-01-01

26

Fatigue crack initiation and growth at holes in a high strength bainitic roller bearing steel when loaded with non-proportional shear and compressive cycles  

Microsoft Academic Search

Fatigue initiation from an artificial defect was investigated for a bainitic high strength roller bearing steel. Thin walled pipe specimens with small holes were subjected to multi-axial and non-proportional load cycles. The experimental fatigue crack positions around the hole were predicted with the Findley critical plane criterion. The criterion also ranked the severeness of three load sequences with respect to

Bo Alfredsson; Veronica Wåtz; Erik Olsson

2011-01-01

27

Investigating Science through Bears (and Teddy Bears).  

ERIC Educational Resources Information Center

Presents cooperative classroom projects using science as the initial basis for the study of bears. These projects may also involve other areas of the curriculum such as mathematics, art, and music. "Black Bear" activities include following a park ranger to study our National Parks and researching and building a full-sized brown bear habitat. (AIM)

Smith, Karlene Ray

1997-01-01

28

Investigating Science through Bears (and Teddy Bears).  

ERIC Educational Resources Information Center

|Presents cooperative classroom projects using science as the initial basis for the study of bears. These projects may also involve other areas of the curriculum such as mathematics, art, and music. "Black Bear" activities include following a park ranger to study our National Parks and researching and building a full-sized brown bear habitat.…

Smith, Karlene Ray

1997-01-01

29

Precision Bearing Grease Selection Guide.  

National Technical Information Service (NTIS)

The study was initiated to develop a precision bearing grease selection guide. As a pan of this study, forty lubricating greases used in precision bearings, including instrument bearings was evaluated in a comprehensive series of laboratory tests in order...

I. Rhee

2006-01-01

30

A convenient method for the preparation of ?-vinylfurans by phosphine-initiated reactions of various substituted enynes bearing a carbonyl group with aldehydes  

Microsoft Academic Search

?-Vinylfurans were obtained by phosphine-initiated cyclization of various enynes bearing a carbonyl group at the ene end in the presence of various aldehydes, in moderate to high yields. The reaction may consist of 1,6-addition of phosphine to the enynes, ring closure, and Wittig reaction between the ylid resulting from cyclization and an aldehyde. Thus, various aldehydes were able to be

Hirofumi Kuroda; Emi Hanaki; Hironori Izawa; Michiko Kano; Hiromi Itahashi

2004-01-01

31

Report to Participants in the Workshops to Initiate a Collaborative Planning Process for the Wyoming State Grizzly Bear Management Plan.  

National Technical Information Service (NTIS)

The Wyoming Game and Fish Department (WGFD) is faced with a knotty problem: how to manage grizzly bears in many parts of the state after they are taken off the endangered list. There are many facets to this problem. However, the question of how to conduct...

B. L. Lamb J. G. Taylor N. Burkardt P. D. Ponds L. Caughlan N. Sexton

2000-01-01

32

Bifunctional oxygen electrodes. Final report  

SciTech Connect

Objective of the research on bifunctional oxygen electrodes for alkaline electrolytes has been to improve significantly both the cathodic and anodic polarization as well as the cycle life of such electrodes. The research has focused on finding high-efficiency, long-life electrocatalysts for O/sub 2/ reduction and generation and achieving an understanding of the mechanisms of the catalysis. Catalyst systems which have been examined in alkaline electrolytes have included the following: various types of carbons and graphites; chemically-modified carbons and graphites using adsorptive attachment (e.g., various quinones, macrocycles and chemical linkages); silver and various intermetallics; various oxide systems including perovskites, spinels, pyrochlores and other mixed transition metal oxides; transition metal macrocycles including porphyrins, phthalocyanines, naphthalocyanines and tetraazaannulenes; and thermally-treated macrocycles. Mechanistic studies have particulary focused on the reduction of O/sub 2/ on various carbon/graphite surfaces and the role of the O/sub 2//sup -/ radical ion.

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

1985-01-01

33

Process and apparatus for the release of a prestress initially applied to a mechanism such as a bearing on board a space vehicle  

NASA Astrophysics Data System (ADS)

In space vehicles, mechanisms such as ball bearings are subject to an initial preload or prestress enabling them to withstand the vibrations caused by the launch and without leading to any clearance or play. A member made from a shape memory material, for example, makes it possible under the effect of its elongation to release the preload when the vehicle is in the operational mode. The control of the release can take place by means of a heating resistor, whose energization leads to the member clearing its shape change temperature and releasing the prestress. The heating can also be done by means of solar energy. The process and apparatus of this invention makes it possible in a particularly simple and non-constraining manner to release the prestress applied to a mechanism during launch without incurring any risk of deterioration to the mechanism during the launch phase and without the need to use a rigid member linked with a pyrotechnic control.

Schoeffter, Jean-Pierre

1992-01-01

34

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

Microsoft Academic Search

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

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

2005-01-01

35

Benzyl and Phenylthiomethyl Silanes: A New Class of Bifunctional Linchpins for Type II Anion Relay Chemistry (ARC)  

PubMed Central

A new class of bifunctional linchpins bearing electrophilic sites ? or ? to a silyl group have been designed, synthesized and demonstrated to be competent in tri-component unions exploiting Type II Anion Relay Chemistry (ARC). High diastereoselectivities were observed when a phenyl moiety (R2) served as an anion stabilizing group (ASG) adjacent to a methyl susbtituent (R1), while diastereomeric mixtures were obtained when a phenylthiol moiety served as the ASG, irrespective of ?-substitution.

Smith, Amos B.; Tong, Rongbiao

2010-01-01

36

Benzyl and phenylthiomethyl silanes: a new class of bifunctional linchpins for type II anion relay chemistry (ARC).  

PubMed

A new class of bifunctional linchpins bearing electrophilic sites beta or gamma to a silyl group have been designed, synthesized, and demonstrated to be competent in tricomponent unions exploiting Type II Anion Relay Chemistry (ARC). High diastereoselectivities were observed when a phenyl moiety (R(2)) served as an anion-stabilizing group (ASG) adjacent to a methyl susbtituent (R(1)), while diastereomeric mixtures were obtained when a phenylthiol moiety served as the ASG, irrespective of alpha-substitution. PMID:20180531

Smith, Amos B; Tong, Rongbiao

2010-03-19

37

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

38

THRUST BEARING  

DOEpatents

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

Heller, P.R.

1958-09-16

39

Elastic Bearing.  

National Technical Information Service (NTIS)

The common ball bearings and sliding bearings are well known to people since they are widely employed in modern industries such as trains, automobiles, ships, aircraft, machine tools, instruments, etc. They have also been used in many household appliances...

1985-01-01

40

Bifunctional Janus microparticles with spatially segregated proteins  

PubMed Central

We present a fabrication process to create bifunctional microparticles displaying two distinct proteins that are spatially segregated onto the surface hemispheres. Silica and polystyrene microparticles with 2.0 ?m, 4.1 ?m, and 4.7 ?m diameters are processed with metal deposition to form two chemically distinct and segregated hemispheres. The surface of each hemisphere is then separately derivatized with biological proteins using different chemical conjugation strategies. These bifunctional Janus particles possess biologically relevant, native conformation proteins attached to a biologically-unreactive and safe substrate. They also display high densities of each type of proteins which may enable a range of capabilities that monofunctional particles cannot, such as improved targeting of drugs and bioimaging agents.

Tang, Jennifer L.; Schoenwald, Kipp; Potter, Daniel; White, David; Sulchek, Todd

2012-01-01

41

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

PubMed

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

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

1999-12-01

42

Journal bearing  

DOEpatents

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

Menke, John R. (New York, NY); Boeker, Gilbert F. (New York, NY)

1976-05-11

43

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

PubMed Central

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.

Smith, Amos B.; Kim, Won-Suk

2011-01-01

44

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

2011-01-18

45

GAS BEARING  

DOEpatents

A gas lubricated bearing for a rotating shaft is described. The assembly comprises a stationary collar having an annular member resiliently supported thereon. The collar and annular member are provided with cooperating gas passages arranged for admission of pressurized gas which supports and lubricates a bearing block fixed to the rotatable shaft. The resilient means for the annular member support the latter against movement away from the bearing block when the assembly is in operation.

Skarstrom, C.W.

1960-09-01

46

Bifunctional bacterial magnetic nanoparticles for tumor targeting  

NASA Astrophysics Data System (ADS)

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

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

2012-01-01

47

Seismic bearing  

Microsoft Academic Search

Textron Systems (Textron) has been using geophones for target detection for many years. This sensing capability was utilized for detection and classification purposes only. Recently Textron has been evaluating multiaxis geophones to calculate bearings and track targets more specifically personnel. This capability will not only aid the system in locating personnel in bearing space or cartesian space but also enhance

Dennis Power

2009-01-01

48

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

49

Uniting Anion Relay Chemistry with Pd-Mediated Cross Coupling: Design, Synthesis and Evaluation of Bifunctional Aryl and Vinyl Silane Linchpins  

PubMed Central

Union of Type II Anion Relay Chemistry (ARC) with Pd-induced Cross Coupling Reactions (CCR) has been achieved, in conjunction with the design, synthesis, and evaluation of a new class of bifunctional linchpins, comprising a series of vinyl silanes bearing ?- or ?-electrophilic sites. The synthetic tactic permits both alkylation and Pd-mediated CCR of the anions derived via 1,4-silyl C(sp2)?O Brook Rearrangements.

Smith, Amos B.; Kim, Won-Suk; Tong, Rongbiao

2009-01-01

50

Uniting anion relay chemistry with Pd-mediated cross coupling: design, synthesis and evaluation of bifunctional aryl and vinyl silane linchpins.  

PubMed

Union of type II Anion Relay Chemistry (ARC) with Pd-induced Cross Coupling Reactions (CCR) has been achieved, in conjunction with the design, synthesis, and evaluation of a new class of bifunctional linchpins, comprising a series of vinyl silanes bearing beta- or gamma-electrophilic sites. The synthetic tactic permits both alkylation and Pd-mediated CCR of the anions derived via 1,4-silyl C(sp(2))-->O Brook Rearrangements. PMID:20028107

Smith, Amos B; Kim, Won-Suk; Tong, Rongbiao

2010-02-01

51

Method for the synthesis of a bifunctional complex  

US Patent & Trademark Office Database

Disclosed is a method for obtaining a bifunctional complex comprising a display molecule part and a coding part, wherein a nascent bifunctional complex comprising a chemical reaction site and a priming site for enzymatic addition of a tag is reacted at the chemical reaction site with one or more reactants, and provided with respective tag(s) identifying the reactants(s) at the priming site using one or more enzymes.

Freskgard; Per-Ola (Norrkorping, SE); Franch; Thomas (Copenhagen N., DK); Gouliaev; Alex Haahr (Veksoe Sjaelland, DK); Lundorf; Mikkel Dybro (Copenhagen O, DK); Felding; Jakob (Charlottenlund, DK); Olsen; Eva Kampmann (Herlev, DK); Holtmann; Anette (Ballerup, DK); Jakobsen; Soeren Nyboe (Frederiksberg, DK); Sams; Christian Klarner (Vaerloese, DK); Glad; Sanne Schroeder (Ballerup, DK); Jensen; Kim Birkebaek (Roedovre, DK); Pedersen; Henrik (Bagsvaerd, DK)

2012-06-26

52

Synthesis and preclinical evaluation of bifunctional ligands for improved chelation chemistry of 90Y and 177Lu for targeted radioimmunotherapy.  

PubMed

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, and 3p-C-DEPA for radiolabeling kinetics with (90)Y and (177)Lu. 3p-C-NETA-trastuzumab conjugate exhibited extremely rapid complexation kinetics with (90)Y and (177)Lu. (90)Y-3p-C-NETA-trastuzumab and (177)Lu-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 (177)Lu-radiolabeled trastuzumab conjugate using nude mice bearing ZR-75-1 human breast cancer. (177)Lu-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 (90)Y and (177)Lu and has the 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

2012-08-10

53

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.

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

2012-01-01

54

A new approach to wastewater remediation based on bifunctional electrodes.  

PubMed

Here we report an a novel approach, the marriage of photocatalytic degradation and electrochemical oxidation, to wastewater remediation based on the use of bifunctional electrodes. To illustrate this innovative technique, TiO2/Ti/ Ta2O5-IrO2 bifunctional electrodes were prepared using a facile thermal decomposition technique and employed in this study. The TiO2 photocatalyst was coated on one side of the Ti substrate, while the Ta2O5-IrO2 electrocatalytic thin film was coated on the other side. The fabricated bifunctional electrodes were characterized by scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS). The performance of the bifunctional electrodes was tested using both 4-nitrophenol (4-NPh) and 2-nitrophenol (2-NPh) as model pollutants. Our study demonstrates that the prepared bifunctional electrodes exhibit high efficiency for both 4-NPh and 2-NPh degradation. In the degradation of 4-NPh a rate constant of 1.06 x 10(-2) min(-1) was created and a rate constant of 1.93 x 10(-2) min(-1) was produced for 2-NPh by the combination of the photochemical and electrochemical oxidation on the novel bifunctional electrodes, quadruple the rate constant created by the individual photochemical and photoelectrochemical methods. The innovative approach described in this study provides a very promising and energy efficient environmentally friendly technology for water purification and waste effluent treatment. PMID:19673313

Asmussen, Robert Matthew; Tian, Min; Chen, Aicheng

2009-07-01

55

Yellowstone Grizzly Bear Investigations 1997.  

National Technical Information Service (NTIS)

The Interagency Grizzly Bear Study Team (IGBST) was initiated in 1973 and is a cooperative effort of the National Park Service, Forest Service, and since 1974 the States of Idaho, Montana, and Wyoming. The IGBST conducts research that provides information...

C. C. Schwartz M. A. Haroldson

1998-01-01

56

Yellowstone Grizzly Bear Investigations 1992.  

National Technical Information Service (NTIS)

The Interagency Grizzly Bear Study Team (IGBST) was initiated in 1973 and is a cooperative effort of the National Park Service, Forest Service, and since 1974 the States of Idaho, Montana, and Wyoming. The IGBST conducts research that provides information...

R. R. Knight B. M. Blanchard D. J. Mattson

1993-01-01

57

Yellowstone Grizzly Bear Investigations 1993.  

National Technical Information Service (NTIS)

The Interagency Grizzly Bear Study Team (IGBST) was initiated in 1973 and is a cooperative effort of the National Park Service, Forest Service, and since 1974 the States of Idaho, Montana, and Wyoming. The IGBST conducts research that provides information...

R. R. Knight B. M. Blanchard

1994-01-01

58

Yellowstone Grizzly Bear Investigations 1998.  

National Technical Information Service (NTIS)

The Interagency Grizzly Bear Study Team (IGBST) was initiated in 1973 and is a cooperative effort of the National Park Service, Forest Service, and since 1974 the States of Idaho, Montana, and Wyoming. The IGBST conducts research that provides information...

C. C. Schwartz M. A. Haroldson

1999-01-01

59

Yellowstone Grizzly Bear Investigations 1994.  

National Technical Information Service (NTIS)

The Interagency Grizzly Bear Study Team (IGBST) was initiated in 1973 and is a cooperative effort of the National Park Service, Forest Service, and since 1974 the States of Idaho, Montana, and Wyoming. The IGBST conducts research that provides information...

R. R. Knight B. M. Blanchard

1995-01-01

60

Yellowstone Grizzly Bear Investigations 1990.  

National Technical Information Service (NTIS)

The Interagency Grizzly Bear Study Team (IGBST) was initiated in 1973 and is a cooperative effort of the National Park Service, Forest Service, and since 1974 the States of Idaho, Montana, and Wyoming. The IGBST conducts research that provides information...

R. R. Knight B. M. Blanchard D. J. Mattson

1991-01-01

61

Yellowstone Grizzly Bear Investigations 1991.  

National Technical Information Service (NTIS)

The Interagency Grizzly Bear Study Team (IGBST) was initiated in 1973 and is a cooperative effort of the National Park Service, Forest Service, and since 1974 the States of Idaho, Montana, and Wyoming. The IGBST conducts research that provides information...

R. R. Knight B. M. Blanchard D. J. Mattson

1992-01-01

62

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.

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

63

Preparation of bifunctional mesoporous silica nanoparticles by orthogonal click reactions and their application in cooperative catalysis.  

PubMed

The synthesis of bifunctional mesoporous silica nanoparticles is described. Two chemically orthogonal functionalities are incorporated into mesoporous silica by co-condensation of tetraethoxysilane with two orthogonally functionalized triethoxyalkylsilanes. Post-functionalization is achieved by orthogonal surface chemistry. A thiol-ene reaction, Cu-catalyzed 1,3-dipolar alkyne/azide cycloaddition, and a radical nitroxide exchange reaction are used as orthogonal processes to install two functionalities at the surface that differ in reactivity. Preparation of mesoporous silica nanoparticles bearing acidic and basic sites by this approach is discussed. Particles are analyzed by solid state NMR spectroscopy, elemental analysis, infrared-spectroscopy, and scanning electron microscopy. As a first application, these particles are successfully used as cooperative catalysts in the Henry reaction. PMID:23132649

Dickschat, Arne T; Behrends, Frederik; Bühner, Martin; Ren, Jinjun; Weiss, Mark; Eckert, Hellmut; Studer, Armido

2012-11-06

64

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

65

Journal Bearings.  

National Technical Information Service (NTIS)

The instability of zero or lightly loaded shafts when they rotate at high speeds in bearings in low viscosity lubricants is considered . This instability refers to a selfexcited fractional frequency whirl or tendency of the shaft center to orbit the beari...

F. T. Schuller W. A. Moore

1973-01-01

66

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

PubMed

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

Nagradova, Natalya

2003-08-01

67

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.

Frullano, Luca; Caravan, Peter

2012-01-01

68

Fluid Lubricated Bearing Construction.  

National Technical Information Service (NTIS)

A fluid lubricated thrust bearing assembly is described. A first bearing member has a plain bearing surface; a second bearing member has a bearing surface confronting the surface of the first bearing and is provided with at least one spiral groove extendi...

J. R. Dunning H. A. Boorse G. F. Boeker

1976-01-01

69

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.

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

2010-01-01

70

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

PubMed

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

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

2013-02-25

71

Fluid lubricated bearing construction  

DOEpatents

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

Dunning, John R. (Riverdale, NY); Boorse, Henry A. (Leonia, NJ); Boeker, Gilbert F. (New York, NY)

1976-01-01

72

Crystallization of bi-functional ligand protein complexes.  

PubMed

Homodimerization is important in signal transduction and can play a crucial role in many other biological systems. To obtaining structural information for the design of molecules able to control the signalization pathways, the proteins involved will have to be crystallized in complex with ligands that induce dimerization. Bi-functional drugs have been generated by linking two ligands together chemically and the relative crystallizability of complexes with mono-functional and bi-functional ligands has been evaluated. There are problems associated with crystallization with such ligands, but overall, the advantages appear to be greater than the drawbacks. The study involves two matrix metalloproteinases, MMP-12 and MMP-9. Using flexible and rigid linkers we show that it is possible to control the crystal packing and that by changing the ligand-enzyme stoichiometric ratio, one can toggle between having one bi-functional ligand binding to two enzymes and having the same ligand bound to each enzyme. The nature of linker and its point of attachment on the ligand can be varied to aid crystallization, and such variations can also provide valuable structural information about the interactions made by the linker with the protein. We report here the crystallization and structure determination of seven ligand-dimerized complexes. These results suggest that the use of bi-functional drugs can be extended beyond the realm of protein dimerization to include all drug design projects. PMID:23567804

Antoni, Claudia; Vera, Laura; Devel, Laurent; Catalani, Maria Pia; Czarny, Bertrand; Cassar-Lajeunesse, Evelyn; Nuti, Elisa; Rossello, Armando; Dive, Vincent; Stura, Enrico Adriano

2013-04-06

73

A bifunctional biosensor for subcutaneous glucose monitoring by reverse iontophoresis  

Microsoft Academic Search

A continuous, noninvasive glucose monitoring method is necessary for diabetic patients to reduce the risk of hypoglycemia. This paper was to develop a bifunctional biosensor for the simultaneous extracting and detecting the subcutaneous glucose by reverse iontophoresis. The biosensor was constructed by a tri-electrode planar configuration and multi-layer sensitive membrane composed of mediator, enzyme and cross linking agents. A hydrogel

Jian Liu; Liying Jiang; Hongmin Liu; Xinxia Cai

2011-01-01

74

Optimization of bifunctional electrocatalyst for PEM unitized regenerative fuel cell  

Microsoft Academic Search

To find the best operating conditions and oxygen electrode catalyst of the PEM unitized regenerative fuel cell (URFC) system, we examined the effect of reaction conditions and the performance of several bifunctional electrocatalysts for oxygen electrode in a single cell PEM URFC system. When Pt black was employed for both electrodes, the URFC performance improved with increasing cell temperature up

Sung-Dae Yim; Won-Yong Lee; Young-Gi Yoon; Young-Jun Sohn; Gu-Gon Park; Tae-Hyun Yang; Chang-Soo Kim

2004-01-01

75

A novel bifunctional electrocatalyst for unitized regenerative fuel cell  

Microsoft Academic Search

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

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

2010-01-01

76

Squaramides: bridging from molecular recognition to bifunctional organocatalysis.  

PubMed

In this minireview, squaramides are presented from their roots as artificial anion receptors in molecular recognition studies to their recent advances as powerful bifunctional hydrogen-bonding catalysts in asymmetric organocatalysis. The main features of the squaramido functionality and the direct comparison with the analogous ureas and thioureas are also discussed. PMID:21590822

Alemán, José; Parra, Alejandro; Jiang, Hao; Jørgensen, Karl Anker

2011-05-17

77

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.

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

2011-01-01

78

Preparation of a Versatile Bifunctional Zeolite for Targeted Imaging Applications.  

PubMed

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 ((68)Ga) 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

2011-02-01

79

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.

80

Novel bi-functional film ceramic sensors for environmental applications  

Microsoft Academic Search

Two types of bi-functional film sensors have been developed for environmental applications. The first sensing device is based on n-type semiconducting metal oxide WO3 and is fabricated using thin-film surface microfabrication technology. It utilises gas chemisorption at elevated temperatures higher than 300°C as well as water physisorption on grain surfaces at temperatures lower then 150°C. Both humidity and particular pollution

Wenmin Qu; Wojtek Wlodarski; Ray Green; Mike Austin; K. Galatsis

1998-01-01

81

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

82

Engineering isoflavone metabolism with an artificial bifunctional enzyme  

Microsoft Academic Search

Plant secondary metabolism has been a focus of research in recent years due to its significant roles in plant defense and\\u000a in human medicine and nutrition. A protein engineering strategy was designed to more effectively manipulate plant secondary\\u000a metabolite (isoflavonoid) biosynthesis. A bifunctional isoflavone synthase\\/chalcone isomerase (IFS\\/CHI) enzyme was constructed\\u000a by in-frame gene fusion, and expressed in yeast and tobacco.

L. Tian; R. A. Dixon

2006-01-01

83

Investigation of new bifunctional agents: D-Penicillamine  

Microsoft Academic Search

Somatostatin inhibits the release of growth hormone (somatotropin) from the Anterior Pituitary. The main use of derivatives\\u000a of somatostatin is to diagnose growth hormone problems and to use against some forms of cancer which involve growth hormone.\\u000a Also somatostatin suppresses gastric acid secretion, gallbladder contractions, and pancreatic enzyme secretion. The aim of\\u000a the current study is to investigate new bifunctional

C. Acar; S. Teksöz; P. Ünak; F. Z. Biber

2007-01-01

84

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.

Minnesota, Science M.

1995-01-01

85

Thrust bearing for turbocharger  

Microsoft Academic Search

A thrust bearing is described for sustaining the thrust load of the rotor shaft of a turbocharger, the thrust bearing having a first and second opposed side surface, comprising: A first groove formed in the first side surface of the thrust bearing for holding lubricating oil supplied to the bearing; at least one first oil passage extending from the groove

T. Tamura; N. Shibata; T. Kawakami

1987-01-01

86

Polymer-supported enantioselective bifunctional catalysts for nitro-Michael addition of ketones and aldehydes.  

PubMed

Introduction of an L-amino acid as a spacer and a urea-forming moiety in a polymer-supported bifunctional urea-primary amine catalyst, based on (1R, 2R)-(+)-1,2-diphenylethylenediamine, significantly improves the catalyst's activity and stereoselectivity in the asymmetric addition of ketones and aldehydes to nitroolefins. Yields and enantioselectivities, unprecedented for immobilized catalysts, were obtained with such challenging donors as acetone, cyclopentanone, and ?,?-disubstituted aldehydes, which usually perform inadequately in this reaction (particularly when a secondary-amine-based catalyst is used). Remarkably, though in the examined catalysts the D-amino acids as spacers were significantly inferior to the L?isomers, for the chosen configuration of the diamine (match-mismatch pairs) the size of the side chain of the amino acid hardly influenced the enantioselectivity of the catalyst. These results, combined with the reactivity profile of the catalysts with substrates bearing two electron-withdrawing groups and the behavior of the catalysts' analogues based on tertiary (rather than primary) amine, suggest an enamine-involving addition mechanism and a particular ordered C-C bond-forming transition state as being responsible for the catalytic reactions with high enantioselectivity. PMID:22250008

Tuchman-Shukron, Lital; Miller, Scott J; Portnoy, Moshe

2012-01-16

87

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

PubMed Central

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

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

2013-01-01

88

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

PubMed Central

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

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

2009-01-01

89

Defective DNA cross-link removal in Chinese hamster cell mutants hypersensitive to bifunctional alkylating agents  

SciTech Connect

DNA repair-deficient mutants from five genetic complementation groups isolated previously from Chinese hamster cells were assayed for survival after exposure to the bifunctional alkylating agents mitomycin C or diepoxybutane. Groups 1, 3, and 5 exhibited 1.6- to 3-fold hypersensitivity compared to the wild-type cells, whereas Groups 2 and 4 exhibited extraordinary hypersensitivity. Mutants from Groups 1 and 2 were exposed to 22 other bifunctional alkylating agents in a rapid assay that compared cytotoxicity of the mutants to the wild-type parental strain, AA8. With all but two of the compounds, the Group 2 mutant (UV4) was 15- to 60-fold more sensitive than AA8 or the Group 1 mutant (UV5). UV4 showed only 6-fold hypersensitivity to quinacrine mustard. Alkaline elution measurements showed that this compound produced few DNA interstrand cross-links but numerous strand breaks. Therefore, the extreme hypersensitivity of mutants from Groups 2 and 4 appeared specific for compounds the main cytotoxic lesions of which were DNA cross-links. Mutant UV5 was only 1- to 4-fold hypersensitive to all the compounds. Although the initial number of cross-links was similar for the three cell lines, the efficiency of removal of cross-links was lowest in UV4 and intermediate in UV5. These results suggest that the different levels of sensitivity are specifically related to different efficiencies of DNA cross-link removal. The phenotype of hypersensitivity to both UV radiation and cross-link damage exhibited by the mutants in Groups 2 and 4 appears to differ from those of the known human DNA repair syndromes.

Hoy, C.A.; Thompson, L.H.; Mooney, C.L.; Salazar, E.P.

1985-04-01

90

Design and Testing of Bi-Functional, P-Loop-Targeted MDM2 Inhibitors.  

National Technical Information Service (NTIS)

This proposal is to design and evaluate a novel class of bifunctional MDM2 inhibitors, based on the discovery that nucleotides can bind to the P-loop of MDM2 and cause its relocalization to the nucleolus. Such bifunctional compounds will be designed to ta...

C. L. Prives

2006-01-01

91

Purification and Characterization of Bifunctional Lysine-Ketoglutarate Reductase\\/Saccharopine Dehydrogenase from Developing Soybean Seeds  

Microsoft Academic Search

Both in mammals and plants, excess lysine (Lys) is catabolized via saccharopine into a-amino adipic semialdehyde and glutamate by two consecutive enzymes, Lys-ketoglutarate reductase (LKR) and saccharopine dehydrogenase (SDH), which are linked on a single bifunctional polypeptide. To study the control of metabolite flux via this bifunctional enzyme, we have purified it from developing soybean (Glycine max) seeds. LKR activity

Daphna Miron; Sari Ben-Yaacov; Dalit Reches; Avigail Schupper; Gad Galili

2000-01-01

92

Hydroconversion of Methylcyclohexane on Bifunctional Sulfated Zirconia-Supported Platinum Catalysts  

Microsoft Academic Search

A series of bifunctional catalysts prepared from sulfated zirconias (SZs) by deposition of platinum were studied in the conversion of methylcyclohexane (MCH). The main reaction observed is the isomerization to alkylcyclopentanes (ACPs), the slow step of which is the acid-catalyzed contraction of the ring. The positive order with respect to hydrogen pressure is tentatively assigned either to a nonclassical bifunctional

François Figueras; Bernard Coq; Christian Walter; Jean-Yves Carriat

1997-01-01

93

Primary and tertiary amines bifunctional graphene oxide for cooperative catalysis.  

PubMed

In this study, primary and tertiary amine bifunctional graphene oxide (GO-NH2-NEt2) was prepared by silylanization of graphene oxide (GO) with amine-terminal silanes. The obtained GO-NH2-NEt2 was characterized by infrared spectrum (FTIR), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), high-resolution transmission electron microscopy (HRTEM) and X-ray photoelectron spectroscopy (XPS). Systematic studies demonstrated the GO-NH2-NEt2 had excellent catalytic activities and 100% selectivity in the classic trans-?-nitrostyrene forming reaction. PMID:23714770

Zhang, Wenfeng; Wang, Shanshan; Ji, Junyi; Li, Yang; Zhang, Guoliang; Zhang, Fengbao; Fan, Xiaobin

2013-05-29

94

Kinetic properties of Mycobacterium tuberculosis bifunctional GlmU  

Microsoft Academic Search

The UDP-N-acetylglucosamine (UDP-GlcNAc) is present as one of the glycosyl donors for disaccharide linker (d-N-GlcNAc-l-rhamnose) and the precursor of peptidoglycan in mycobacteria. The bifunctional enzyme GlmU involves in the last two sequential\\u000a steps of UDP-GlcNAc synthetic pathway. Glucosamine-1-phosphate acetyltransferase catalyzes the formation of N-acetylglucosamine-1-phosphate\\u000a (GlcNAc-1-P) from glucosamine-1-phosphate (GlcN-1-P) and acetyl coenzyme A (Acetyl CoA), and N-acetylglucosamine-1-phosphate\\u000a uridyltransferase catalyzes the synthesis

Yan Zhou; Yi Xin; Shanshan Sha; Yufang Ma

95

Improved Hybrid Bearings.  

National Technical Information Service (NTIS)

Nitriding technology was determined to significantly enhance the performance of steel bearing rings coupled with silicon nitride balls. NBD-200 silicon nitride was tested in two different sized full scale bearing tests with two nitrided steel ring materia...

M. M. Dezzani P. K. Pearson

1994-01-01

96

High Efficiency Magnetic Bearings.  

National Technical Information Service (NTIS)

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, param...

P. A. Studer C. P. Jayaraman D. K. Anand J. A. Kirk

1993-01-01

97

Magnetic bearing update.  

National Technical Information Service (NTIS)

Stabilization of whirl instability by floppy, viscous bearing mounts is discussed and required material properties are estimated for the new tilt-whirl mode in eddy-current stabilized magnetic bearings. A relatively low Young's modules Y (approximately) 1...

T. K. Fowler

1995-01-01

98

High-Speed Video Analysis of Rotor-Retainer-Bearing-Contacts Due to Failure of Active Magnetic Bearings  

Microsoft Academic Search

.Abstract - This paper addresses the experimental analysis and the modeling of rotor-retainer-bearing- contacts due to failure of active magnetic bearings. The most critical state that can occur, is the backward whirl motion, which is initiated by friction forces acting on the rotor. To model and simulate the highly nonlinear behavior of the system, a good bearing model and an

Marlene Helfert; Martin Ernst; Rainer Nordmann

99

Magring sealed ball bearing  

NASA Astrophysics Data System (ADS)

A one piece, magnetic liquid shaft seal installed between the ball bearing races provides a hermetic dynamic seal. This paper discusses the advantages of such a sealed ball bearing and includes experimental data dealing with differential pressure capability, effect of mixing of magnetic liquid with grease on bearing noise, etc.

Hirao, A.; Ezekiel, F. D.

1987-03-01

100

High Strength Ceramics Bearings.  

National Technical Information Service (NTIS)

Rotordynamics-Seal Research is currently performing on a 6 month contract to develop high strength ceramic bearings using a new low cost process. This effort consists of development of a ceramic bearing design, fabrication, and testing of the bearing in a...

J. K. Scharrer

1997-01-01

101

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

102

Performance of a hybrid cylindrical roller bearing  

NASA Astrophysics Data System (ADS)

A 206-size hybrid (ceramic/steel) cylindrical roller bearing was tested in MIL-L-23699 C oil at several speeds and loads. Heat-generation data was collected and subsequently correlated with bearing-analysis software. Bearing-cage slip data was also collected at various oil-flow rates, oil temperatures, and with both MIL-L-7808 J and MIL-L-23699 C oils. The hybrid bearing was tested in MIL-L-23699 C oil for for 25 hours at 2220 N radial load and 1.08 MDN shaft speed. The hybrid bearing technology demonstrated in the report is applicable to the Integrated High Performance Turbine Engine Technology Initiative.

Schrader, Stephen M.

1992-08-01

103

Performance of a hybrid cylindrical roller bearing  

SciTech Connect

A 206-size hybrid (ceramic/steel) cylindrical roller bearing was tested in MIL-L-23699 C oil at several speeds and loads. Heat-generation data was collected and subsequently correlated with bearing-analysis software. Bearing-cage slip data was also collected at various oil-flow rates, oil temperatures, and with both MIL-L-7808 J and MIL-L-23699 C oils. The hybrid bearing was tested in MIL-L-23699 C oil for for 25 hours at 2220 N radial load and 1.08 MDN shaft speed. The hybrid bearing technology demonstrated in the report is applicable to the Integrated High Performance Turbine Engine Technology Initiative. 15 refs.

Schrader, S.M. (General Motors Corp., Allison Gas Turbine Div., Indianapolis, IN (United States))

1992-08-01

104

Status of understanding for bearing materials  

SciTech Connect

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.

1984-04-01

105

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

PubMed Central

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

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

2008-01-01

106

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

107

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.

Mach, Martin

2009-06-17

108

Novel bidirectional air bearing  

NASA Astrophysics Data System (ADS)

Fluid lubricated bearings (ball or journal) exhibit problems of life and contamination in high speed polygonal scanners, particularly at speeds above 15,000 rpm. Grooved air bearings are limited to relatively high manufacturing cost, vertical only attitude, unidirectional rotation, and they tend to ingest debris. A plain journal air bearing is described which is bidirectional, any attitude operation, is free of whirl instability and has low manufacturing cost.

Sherman, Randy J.

1993-12-01

109

A bifunctional DNA binding region in Tn5 transposase  

PubMed Central

Tn5 transposition is a complicated process that requires the formation of a highly ordered protein–DNA structure, a synaptic complex, to catalyse the movement of a sequence of DNA (transposon) into a target DNA. Much is known about the structure of the synaptic complex and the positioning of protein–DNA contacts, although many protein–DNA contacts remain largely unstudied. In particular, there is little evidence for the positioning of donor DNA and target DNA. In this communication, we describe the isolation and analysis of mutant transposases that have, for the first time, provided genetic and biochemical evidence for the stage-specific positioning of both donor and target DNAs within the synaptic complex. Furthermore, we have provided evidence that some of the amino acids that contact donor DNA also contact target DNA, and therefore suggest that these amino acids help define a bifunctional DNA binding region responsible for these two transposase–DNA binding events.

Gradman, Richard J; Ptacin, Jerod L; Bhasin, Archna; Reznikoff, William S; Goryshin, Igor Y

2008-01-01

110

Thrust bearing for turbocharger  

SciTech Connect

A thrust bearing is described for sustaining the thrust load of the rotor shaft of a turbocharger, the thrust bearing having a first and second opposed side surface, comprising: A first groove formed in the first side surface of the thrust bearing for holding lubricating oil supplied to the bearing; at least one first oil passage extending from the groove toward the axis of the rotor shaft; at least one second oil passage communicating with the first oil passage and having a plurality of oil holes connected thereto that extend respectively to a plurality of tapering land portions formed on the first and second side surfaces of the thrust bearing so that the axial thrust bearing clearance decreases in a direction of rotation of the shaft; a first and second leg portion defining a cut out portion formed exclusively in the lower end portion of the thrust bearing; a planar portion formed in the end surface of the thrust bearing along the first and second cut out portion and forming a portion of a closed loop; and a second groove formed between the planar portion and the surfaces on which the shaft bears wherein the oil holes are formed in proximity to a point of maximum thrust clearance of the tapering land portions.

Tamura, T.; Shibata, N.; Kawakami, T.

1987-01-27

111

On The Dynamic and Thermal Performance of a Zero Clearance Auxiliary Bearing(zcab) for a Magnetic Bearing System  

Microsoft Academic Search

Structural and thermal analysis of a zero clearance auxiliary bearing (ZCAB) for magnetic bearing systems is presented. The ZCAB consists a series of rollers whose centers are initially placed on a circle. At the open condition all rollers have an initial clearance about the rotating shaft. As the shaft drops on the ZCAB rollers, either due to failure of the

Mohsen Salehi; Hooshang Heshmat

2000-01-01

112

Prototypes of bifunctional photochromic and electro-optical systems  

NASA Astrophysics Data System (ADS)

Two types of bifunctional films having both electro-optical and photochromic properties have been prepared and investigated. These films are able to modulate the light transmission by means of suitable electric fields and to change their color under light irradiation. One of the films is fluid-like, being an emulsion of a liquid crystal and a photochrome in an organic monomer. It is defined as a photochromic emulsion dispersed liquid crystal (PEDLC). The other film is solid, having the structure of a polymer dispersed liquid crystal and containing a small percentage of photochrome; it is defined as a photochromic polymer dispersed liquid crystal (PPDLC). The solid films were obtained by photopolymerizing the fluid one. The electro-optical and photochromic properties of these films were investigated. To choose suitable photochromic components, the color-forming and color-bleaching kinetics of some compounds of the classes of spiro-oxazines and spiropyrans were preliminarily investigated in the components of the matrix (liquid crystals and monomers). They generally exhibited a better colorability in the matrix, as compared with organic solvents, due to decreasing of the bleaching rate. Their presence did not alter the electro-optical properties of the films with respect to those of PDLC and EDLC systems. Some significant variations in the color-forming and color-bleaching processes, observed for some of the photochromes dispersed in PDLC films, are discussed. Two of them were found to have the prerequisites of colorability, reversibility, and durability to be used in the bifunctional devices. The results are promising in view of the future involvement of these films in technology.

Chidichimo, G.; Formoso, P.; Manfredi, S.; Favaro, G.; Mazzucato, U.; Romani, A.

2001-11-01

113

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

SciTech Connect

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

Droege, P.

1997-03-01

114

Enantioselective heterocyclic synthesis of spiro chromanone-thiochroman complexes catalyzed by a bifunctional indane catalyst.  

PubMed

Novel asymmetric domino reactions of benzylidenechroman-4-ones and 2-mercaptobenzaldehydes for efficient construction of spiro chromanone-thiochroman complexes were accomplished with high yields and excellent selectivities via a novel bifunctional indane catalyst. PMID:21052574

Gao, Yaojun; Ren, Qiao; Wu, Hao; Li, Maoguo; Wang, Jian

2010-11-04

115

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

116

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

117

Photorefractive composite materials with bi-functional charge transporting second-order nonlinear optical chromophores  

Microsoft Academic Search

Two bi-functional chromophores have been developed which possess second-order nonlinear optical and charge transporting properties. The second-order nonlinearity arises from conjugated structures terminated by donor and acceptor groups and the charge transporting property results from a triphenylamine moiety. The bi-functionality of the chromophores is confirmed by the large electro-optic coefficients and high photoconductivities of composites containing these chromophores. These chromophores

Yue Zhang; Saswati Ghosal; Martin K. Casstevens; Ryszard Burzynski

1996-01-01

118

Opioid Bifunctional Ligands from Morphine and the Opioid Pharmacophore Dmt-Tic  

PubMed Central

Bifunctional ligands containing an ester linkage between morphine and the ?-selective pharmacophore Dmt-Tic were synthesized, and their binding affinity and functional bioactivity at the ?, ? and ? opioid receptors determined. Bifunctional ligands containing or not a spacer of ?-alanine between the two pharmacophores lose the ? agonism deriving from morphine becoming partial ? agonists 4 or ? antagonists 5. Partial ? agonism is evidenced only for compound 4. Finally, both compounds showed potent ? antagonism.

Balboni, Gianfranco; Salvadori, Severo; Marczak, Ewa D.; Knapp, Brian I.; Bidlack, Jean M.; Lazarus, Lawrence H.; Peng, Xuemei; Si, Yu Gui; Neumeyer, John L.

2010-01-01

119

Opioid bifunctional ligands from morphine and the opioid pharmacophore Dmt-Tic.  

PubMed

Bifunctional ligands containing an ester linkage between morphine and the ?-selective pharmacophore Dmt-Tic were synthesized, and their binding affinity and functional bioactivity at the ?, ? and ? opioid receptors determined. Bifunctional ligands containing or not a spacer of ?-alanine between the two pharmacophores lose the ? agonism deriving from morphine becoming partial ? agonists 4 or ? antagonists 5. Partial ? agonism is evidenced only for compound 4. Finally, both compounds showed potent ? antagonism. PMID:21216504

Balboni, Gianfranco; Salvadori, Severo; Marczak, Ewa D; Knapp, Brian I; Bidlack, Jean M; Lazarus, Lawrence H; Peng, Xuemei; Si, Yu Gui; Neumeyer, John L

2010-12-08

120

Metal@Silica yolk-shell nanostructures as versatile bifunctional nanocatalysts  

Microsoft Academic Search

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

Ji Chan Park; Hyunjoon Song

2011-01-01

121

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

PubMed

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

Rider, Mark H; Bertrand, Luc; Vertommen, Didier; Michels, Paul A; Rousseau, Guy G; Hue, Louis

2004-08-01

122

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

PubMed Central

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

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

2010-01-01

123

Bearing Lubrication Apparatus.  

National Technical Information Service (NTIS)

The patent described apparatus for lubrication of anti-friction bearings which uses the oil bleeding characteristics of grease. The apparatus consists of a housing for attachment to a bearing and a grease reservoir wherein the grease is retained in a slop...

K. H. Warren

1970-01-01

124

Superconducting bearings in flywheels  

Microsoft Academic Search

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

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

1998-01-01

125

Grizzly Bear Recovery Plan.  

National Technical Information Service (NTIS)

The grizzly bear(Ursusarcios horribilis) was listed as threatened on July 28, 1975. The original recovery plan was approved on January 29, 1982. This is the first revision of that plan. The grizzly bear was originally distributed in various habitats throu...

1993-01-01

126

Fluid lubricated bearing assembly  

Microsoft Academic Search

1. A support for a loaded rotatable shaft comprising in combination on a housing having a fluid-tight cavity encasing an end portion of said shaft, a thrust bearing near the open end of said cavity for supporting the axial thrust of said shaft, said thrust bearing comprising a thrust plate mounted in said housing and a thrust collar mounted on

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

1976-01-01

127

Fluid lubricated bearing assembly  

Microsoft Academic Search

A support for a loaded rotatable shaft is described. The device consists of: a housing having a fluid-tight cavity encasing an end portion of the shaft; a thrust bearing near the open end of the cavity for supporting the axial thrust of the shaft, the thrust bearing comprising a thrust plate mounted in the housing and a thrust collar mounted

H. A. Boorse; G. F. Boeker; J. R. Menke

1976-01-01

128

OTV bearing deflection investigation  

NASA Astrophysics Data System (ADS)

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

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

1993-04-01

129

Bifunctional Chemopreventive Effects of Adenocaulon himalaicum Through Induction of Detoxification Enzymes and Apoptosis.  

PubMed

Abstract Phase II detoxification enzymes are known to play essential roles in the detoxification and elimination of activated carcinogens during tumor initiation, while apoptosis is one of the most important chemopreventive targets for inhibiting tumor promotion in cancer. In this study, we investigated the cancer chemopreventive activity of two plant extracts, the ethanolic extract of Adenocaulon himalaicum (AHE) and the butanolic fraction of AHE (AHB). Both, the AHE and AHB induced NQO1 activity and had relatively high chemoprevention indices (CI=12.4). The AHE and AHB were associated with increased NQO1 and HO-1 mRNA levels via Nrf2-ARE pathway activation. In addition, the AHB increased CYP1A1 activity through AhR-XRE pathway activation. We also found that the AHE and AHB induced apoptosis, as evidenced by phosphatidylserine externalization, an increase in the sub-G0/G1 content, chromatin condensation, poly(ADP-ribose) polymerase cleavage, and p53 induction. These data suggest that AHE and AHB act as bifunctional inducers and that their chemopreventive effects result from the biphasic induction of phase II detoxification enzymes and apoptosis. Therefore, these results suggest that A. himalaicum plant extracts have potential for use as chemopreventive agents for the prevention and/or treatment of human cancers. PMID:23957354

Yun, Ji Ho; Lee, Saet Byoul; Kang, Kyungsu; Lee, Eun Ha; Lee, Hee Ju; Jung, Sang Hoon; Nho, Chu Won

2013-08-01

130

Denaturation-resistant bifunctional colloidal superstructures assembled via the proteinaceous barnase-barstar interface.  

PubMed

To date, a number of biomolecule-mediated nanoparticle self-assembly systems have been developed that are amenable to controllable disassembly under relatively gentle conditions. However, for some applications such as design of self-assembled multifunctional theragnostic agents, high stability of the assembled structures can be of primary importance. Here, we report extraordinarily high durability of protein-assisted nanoparticle self-assembly systems yielding bifunctional colloidal superstructures resistant to extreme denaturing conditions intolerable for most proteins (e.g., high concentrations of chaotropic agents, high temperature). Among the tested systems (barnase-barstar (BBS), streptavidin-biotin, antibody-antigen, and protein A-immunoglobulin), the BBS is notable due to the combination of its high resistance to severe chemical perturbation and unique advantages offered by genetic engineering of this entirely protein-based system. Comparison of the self-assembly systems shows that whereas in all cases the preassembled structures proved essentially resistant to extreme conditions, the ability of the complementary biomolecular pairs to mediate assembly of the initial biomolecule-particle conjugates differs substantially in these conditions. PMID:23351072

Aghayeva, Ulkar F; Nikitin, Maxim P; Lukash, Sergey V; Deyev, Sergey M

2013-02-05

131

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

PubMed Central

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

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

2008-01-01

132

Magnetic bearing update  

SciTech Connect

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

Fowler, T.K.

1995-05-25

133

Novel Bimodal Bifunctional Ligands for Radioimmunotherapy and Targeted MRI  

PubMed Central

The structurally novel bifunctional ligands C-NETA and C-NE3TA, each possessing both acyclic and macrocyclic moieties, were prepared and evaluated as potential chelates for radioimmunotherapy (RIT) and targeted magnetic resonance imaging (MRI). Heptadentate C-NE3TA was fortuitously discovered during the preparation of C-NETA. An optimized synthetic method to C-NETA and C-NE3TA including purification of the polar and tailing reaction intermediates, tert-butyl C-NETA (2) and tert-butyl C-NE3TA (3) using semi-prep HPLC was developed. The new Gd(III) complexes of C-NETA and C-NE3TA were prepared as contrast enhancement agents for use in targeted MRI. The T1 Relaxivity data indicates that Gd(C-NETA) and Gd(C-NE3TA) possess higher relaxivity than Gd(C-DOTA), a bifunctional version of a commercially available MRI contrast agent, Gd(DOTA). C-NETA and C-NE3TA were radiolabeled with 177Lu, 90Y, 203Pb, 205/6Bi and 153Gd, and in vitro stability of the radiolabeled corresponding complexes was assessed in human serum. The in vitro studies indicate that the evaluated radiolabeled complexes were stable in serum for 11 days with the exception being the 203Pb complexes of C-NETA and C-NE3TA which dissociated in serum. C-NETA and C-NE3TA radiolabeled 177Lu, 90Y, or 153Gd complexes were further evaluated for in vivo stability in athymic mice and possess excellent or acceptable in vivo biodistribution profile. 205/6Bi-C-NE3TA exhibited extremely rapid blood clearance and low radioactivity level at the normal organs, while 205/6Bi-C-NETA displayed low radioactivity level in the blood and all of the organs except for the kidney where relatively high renal uptake of radioactivity is observed. C-NETA and C-NE3TA were further modified for conjugation to the monoclonal antibody Trastuzumab.

Chong, Hyun-Soon; Song, Hyun A; Ma, Xiang; Milenic, Diane; Brady, Erik; Lim, Sooyoun; Lee, Haisung; Baidoo, Kewamena; Cheng, Dengfeng; Brechbiel, Martin W

2008-01-01

134

Bifunctional mesoporous zirconium phosphonates for delivery of nucleic acids.  

PubMed

The bifunctional mesoporous zirconium phosphonates (ZrBFs) were synthesized through surfactant-assisted co-condensation of ZrCl(4) with two different phosphonic acids, both 1-phosphomethylproline (H(3)PMP) and 1,4-bis(phosphomethyl)piperazine (BPMP), in a one-pot procedure. The L-proline group of H(3)PMP and piperazine group of BPMP in the frameworks endow ZrBFs with pH-controllable release function and high cell penetration capability, which was derived from the reversible protonation-deprotonation of L-proline groups and piperazine groups on the mesoporous walls under different pH values (pH sensitivity) as well as further functionalization with biological modifiers via the carboxyls in L-proline groups on the outer surface (functionalizability), respectively. ZrBFs, possessing cationic frameworks once formed, exhibit high payload for salmon sperm DNA as model nucleic acid owing to strong electrostatic attraction between them. On the basis of pH-sensitive ZrBFs carriers and assisted by lag-time films coating, the time- and pH-controlled oral colon-targeted nucleic acid delivery systems have been developed, which can carry most of the loaded salmon sperm DNA to the colon under dual control, time control and pH value control. Furthermore, salmon sperm DNA can remain intact during delivery, as evidenced by the fact that the released salmon sperm DNA in the pH transition release experiment still retain its structural integrity and native conformation. Also, fluorescence spectra demonstrate that ZrBFs can be further functionalized with a cell-penetrating peptide of octaarginine (R8) via the carboxyls in L-proline groups of H(3)PMP on the outer surface using a coupling agent, which will enhance the penetration capability of ZrBFs through biomembranes. ZrBFs have a potential application as a new kind of carrier in oral delivery of nucleic acids targeting the colon for gene therapy of colon-related diseases due to their unique bifunctionality. PMID:23347141

Tang, Yan; Ren, Yubao; Shi, Xin

2013-01-24

135

Bearings. Volume I.  

National Technical Information Service (NTIS)

This bibliography contains a selection of references to reports on bearings, cataloged by the Defense Documentation Center since 1953. The present volume, Volume I, is a compilation of 232 unclassified references with unlimited distribution. These same re...

1969-01-01

136

Optimal synchronizability of bearings.  

PubMed

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)]. 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. PMID:23432250

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

2013-02-07

137

Effect of Bearing Defects.  

National Technical Information Service (NTIS)

This program determined the relationship between selected raceway surface defects and performance and life of miniature ball bearing. The first phase of this two phase program developed the test plan for utilization in the second phase test and evaluation...

C. G. Beecher

1974-01-01

138

Bearing Capacity of Soils.  

National Technical Information Service (NTIS)

This manual presents guidelines for calculation of the bearing capacity of soil under shallow and deep foundations supporting various types of structures and embankments. This information is generally applicable to foundation investigation and design cond...

1992-01-01

139

Optical bifunctionality of europium-complexed luminescent graphene nanosheets.  

PubMed

Graphene is an intriguing two-dimensional material, which could be modified for achieving tunable properties with many applications. Photoluminescence of graphene due to plasmonic emission is well-known, however, attempts to develop strong luminescent graphene have been difficult. Synthesis of a graphene-based material with a dual optical functionality, namely quenching the fluorescence of organic dyes while maintaining its own self-luminescence, is an interesting and challenging proposition. Here, we demonstrate this optical bifunctionality in a lattice-modified luminescent graphene, where europium(III) cations are complexed with graphene through oxygen functionalities. After excitation at 314 nm, a hypersensitive red emission is observed at 614 and 618 nm showing the complexation of europium(III) with graphene. We demonstrate dual functionality of this graphene by the quenching of luminescence of Rhodamine-B while displaying its own hypersensitive red emission. The decay lifetime observed through the time-resolved spectroscopy confirms its potential for applications in biosensing as well as optoelectronics. PMID:22066720

Gupta, Bipin Kumar; Thanikaivelan, Palanisamy; Narayanan, Tharangattu N; Song, Li; Gao, Wei; Hayashi, Takuya; Reddy, Arava Leela Mohana; Saha, Avishek; Shanker, Virendra; Endo, Morinobu; Martí, Angel A; Ajayan, Pulickel M

2011-11-15

140

Monodisperse Magneto-Fluorescent Bifunctional Nanoprobes for Bioapplications  

NASA Astrophysics Data System (ADS)

We present the work on the synthesis of dye-doped monodisperse Fe/SiO2 core/shell nanoparticles as bifunctional probes for bioapplications. Magnetic nanoparticles (NP) have been widely studied as nano-probes for bio-imaging, sensing as well as for cancer therapy. Among all the NPs, Fe NPs have been the focus because they have very high magnetization. However, Fe NPs are usually not stable in ambient due to the fast surface oxidation of the NPs. On the other hand, dye molecules have long been used as probes for bio-imaging. But they are sensitive to environmental conditions. It requires passivation for both so that they can be stable for applications. In this work, monodisperse Fe NPs with sizes ranging from 13-20 nm have been synthesized through the chemical thermal-decomposition in a solution. Silica shells were then coated on the Fe NPs by a two-phase oil-in-water method. Dye molecules were first bonded to a silica precursor and then encapsulated into the silica shell during the coating process. The silica shells protect both the Fe NPs and dye molecules, which makes them as robust probes. The dye doped Fe/SiO2 core/shell NPs remain both highly magnetic and highly fluorescent. The stable dye doped Fe/SiO2NPs have been used as a dual functional probe for both magnetic heating and local nanoscale temperature sending, and their performance will be reported.

Zhang, Hongwang; Huang, Heng; Pralle, Arnd; Zeng, Hao

2013-03-01

141

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

142

Bifunctional Avidin with Covalently Modifiable Ligand Binding Site  

PubMed Central

The extensive use of avidin and streptavidin in life sciences originates from the extraordinary tight biotin-binding affinity of these tetrameric proteins. Numerous studies have been performed to modify the biotin-binding affinity of (strept)avidin to improve the existing applications. Even so, (strept)avidin greatly favours its natural ligand, biotin. Here we engineered the biotin-binding pocket of avidin with a single point mutation S16C and thus introduced a chemically active thiol group, which could be covalently coupled with thiol-reactive molecules. This approach was applied to the previously reported bivalent dual chain avidin by modifying one binding site while preserving the other one intact. Maleimide was then coupled to the modified binding site resulting in a decrease in biotin affinity. Furthermore, we showed that this thiol could be covalently coupled to other maleimide derivatives, for instance fluorescent labels, allowing intratetrameric FRET. The bifunctional avidins described here provide improved and novel tools for applications such as the biofunctionalization of surfaces.

Leppiniemi, Jenni; Maatta, Juha A. E.; Hammaren, Henrik; Soikkeli, Mikko; Laitaoja, Mikko; Janis, Janne; Kulomaa, Markku S.; Hytonen, Vesa P.

2011-01-01

143

AX-5 Space Suit Bearing Torque Investigation.  

National Technical Information Service (NTIS)

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 i...

S. Loewenthal V. Vykukal R. Mackendrick P. Culbertson

1990-01-01

144

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

PubMed

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

2012-02-20

145

Streptavidin binding bifunctional aptamers and their interaction with low molecular weight ligands.  

PubMed

This paper describes the measurement of the binding affinities of two bifunctional RNA aptamers to their respective ligands. The aptamers comprise either a theophylline or malachite green binding sequence fused to a streptavidin binding sequence. These bifunctional aptamers are shown to bind simultaneously to both the small ligand and to streptavidin whether in free solution or on gold surfaces. Binding isotherms for both interactions were measured by different physiochemical techniques: surface plasmon resonance, fluorescence spectroscopy and dynamic light scattering. Both qualitatively and quantitatively there is little difference in binding affinities between the bifunctional aptamers and their monofunctional components. The respective K(d) values for streptavidin binding in the monofunctional aptamer and in the theophylline bifunctional aptamer were 12 nM and 65 nM, respectively whilst the K(d) values for theophylline binding in the monofunctional aptamer and the streptavidin bifunctional aptamer were 300 nM and 120 nM. These results are consistent with treating each aptamer sequence as a module that can be combined with others without significant loss of function. This allows for the use of streptavidin based immobilization strategies without either the cost of biotinylated dNTPs or the variable yields associated with the chemical biotinylation of RNA. PMID:23312325

Le, Thao T; Scott, Steven; Cass, Anthony E G

2012-12-05

146

Purification and characterization of bifunctional lysine-ketoglutarate reductase/saccharopine dehydrogenase from developing soybean seeds.  

PubMed

Both in mammals and plants, excess lysine (Lys) is catabolized via saccharopine into alpha-amino adipic semialdehyde and glutamate by two consecutive enzymes, Lys-ketoglutarate reductase (LKR) and saccharopine dehydrogenase (SDH), which are linked on a single bifunctional polypeptide. To study the control of metabolite flux via this bifunctional enzyme, we have purified it from developing soybean (Glycine max) seeds. LKR activity of the bifunctional LKR/SDH possessed relatively high K(m) for its substrates, Lys and alpha-ketoglutarate, suggesting that this activity may serve as a rate-limiting step in Lys catabolism. Despite their linkage, the LKR and SDH enzymes possessed significantly different pH optima, suggesting that SDH activity of the bifunctional enzyme may also be rate-limiting in vivo. We have previously shown that Arabidopsis plants contain both a bifunctional LKR/SDH and a monofunctional SDH enzymes (G. Tang, D. Miron, J.X. Zhu-Shimoni, G. Galili [1997] Plant Cell 9: 1-13). In the present study, we found no evidence for the presence of such a monofunctional SDH enzyme in soybean seeds. These results may provide a plausible regulatory explanation as to why various plant species accumulate different catabolic products of Lys. PMID:10859195

Miron, D; Ben-Yaacov, S; Reches, D; Schupper, A; Galili, G

2000-06-01

147

Physiological Determinants of Load Bearing Performance at Different March Distances.  

National Technical Information Service (NTIS)

The purpose of this study was to further our knowledge of the physiological determinants of load bearing performance over distances from 2 to 12 km. Twenty eight soldiers, experienced in load bearing, were initially assessed for: aerobic power (VO2max), l...

R. P. Mello A. I. Damokosh K. L. Reynolds C. E. Witt J. A. Vogel

1988-01-01

148

Optimal induction motor bearing selection  

Microsoft Academic Search

There is no choice in bearing selection on small motors (less than 200 HP), where only anti-friction bearings are available. Likewise, a choice does not exist on larger motors (motors in excess of 2000 HP), where various design requirements leave only the sleeve bearing (or tilting pad bearing) as a viable option. On the intermediate size motors a choice exists.

W. R. Finley; M. M. Hodowanec

2003-01-01

149

Adenosine-5'-phosphosulfate--a multifaceted modulator of bifunctional 3'-phospho-adenosine-5'-phosphosulfate synthases and related enzymes.  

PubMed

All sulfation reactions rely on active sulfate in the form of 3'-phospho-adenosine-5'-phosphosulfate (PAPS). In fungi, bacteria, and plants, the enzymes responsible for PAPS synthesis, ATP sulfurylase and adenosine-5'-phosphosulfate (APS) kinase, reside on separate polypeptide chains. In metazoans, however, bifunctional PAPS synthases catalyze the consecutive steps of sulfate activation by converting sulfate to PAPS via the intermediate APS. This intricate molecule and the related nucleotides PAPS and 3'-phospho-adenosine-5'-phosphate modulate the function of various enzymes from sulfation pathways, and these effects are summarized in this review. On the ATP sulfurylase domain that initially produces APS from sulfate and ATP, APS acts as a potent product inhibitor, being competitive with both ATP and sulfate. For the APS kinase domain that phosphorylates APS to PAPS, APS is an uncompetitive substrate inhibitor that can bind both at the ATP/ADP-binding site and the PAPS/APS-binding site. For human PAPS synthase 1, the steady-state concentration of APS has been modelled to be 1.6 ?M, but this may increase up to 60 ?M under conditions of sulfate excess. It is noteworthy that the APS concentration for maximal APS kinase activity is 15 ?M. Finally, we recognized APS as a highly specific stabilizer of bifunctional PAPS synthases. APS most likely stabilizes the APS kinase part of these proteins by forming a dead-end enzyme-ADP-APS complex at APS concentrations between 0.5 and 5 ?M; at higher concentrations, APS may bind to the catalytic centers of ATP sulfurylase. Based on the assumption that cellular concentrations of APS fluctuate within this range, APS can therefore be regarded as a key modulator of PAPS synthase functions. PMID:23517310

Mueller, Jonathan W; Shafqat, Naeem

2013-04-17

150

Adenosine-5?-phosphosulfate - a multifaceted modulator of bifunctional 3?-phospho-adenosine-5?-phosphosulfate synthases and related enzymes  

PubMed Central

All sulfation reactions rely on active sulfate in the form of 3?-phospho-adenosine-5?-phosphosulfate (PAPS). In fungi, bacteria, and plants, the enzymes responsible for PAPS synthesis, ATP sulfurylase and adenosine-5?-phosphosulfate (APS) kinase, reside on separate polypeptide chains. In metazoans, however, bifunctional PAPS synthases catalyze the consecutive steps of sulfate activation by converting sulfate to PAPS via the intermediate APS. This intricate molecule and the related nucleotides PAPS and 3?-phospho-adenosine-5?-phosphate modulate the function of various enzymes from sulfation pathways, and these effects are summarized in this review. On the ATP sulfurylase domain that initially produces APS from sulfate and ATP, APS acts as a potent product inhibitor, being competitive with both ATP and sulfate. For the APS kinase domain that phosphorylates APS to PAPS, APS is an uncompetitive substrate inhibitor that can bind both at the ATP/ADP-binding site and the PAPS/APS-binding site. For human PAPS synthase 1, the steady-state concentration of APS has been modelled to be 1.6 ?m, but this may increase up to 60 ?m under conditions of sulfate excess. It is noteworthy that the APS concentration for maximal APS kinase activity is 15 ?m. Finally, we recognized APS as a highly specific stabilizer of bifunctional PAPS synthases. APS most likely stabilizes the APS kinase part of these proteins by forming a dead-end enzyme–ADP–APS complex at APS concentrations between 0.5 and 5 ?m; at higher concentrations, APS may bind to the catalytic centers of ATP sulfurylase. Based on the assumption that cellular concentrations of APS fluctuate within this range, APS can therefore be regarded as a key modulator of PAPS synthase functions.

Mueller, Jonathan W; Shafqat, Naeem

2013-01-01

151

Double diastereocontrol in bifunctional thiourea organocatalysis: iterative Michael-Michael-Henry sequence regulated by the configuration of chiral catalysts.  

PubMed

The importance and reactivity consequences of the double diastereocontrol in noncovalent bifunctional organocatalysis were studied. The results suggest that the bifunctional thioureas can have synthetic limitations in multicomponent domino or autotandem catalysis. Nevertheless, we provided a means to exploit this behavior and used the configuration of the chiral catalyst as a control element in organo-sequential reactions. PMID:21916428

Varga, Szilárd; Jakab, Gergely; Drahos, László; Holczbauer, Tamás; Czugler, Mátyás; Soós, Tibor

2011-09-14

152

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

PubMed

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. PMID:8280056

Tenhunen, J; Ulmanen, I

1993-12-15

153

Fluid lubricated bearing assembly  

DOEpatents

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

Boorse, Henry A. (Leonia, NJ); Boeker, Gilbert F. (New York, NY); Menke, John R. (New York, NY)

1976-01-01

154

Molecular characterization of a bifunctional glyoxylate cycle enzyme, malate synthase/isocitrate lyase, in Euglena gracilis.  

PubMed

Euglena gracilis induced glyoxylate cycle enzymes when ethanol was fed as a sole carbon source. We purified, cloned and characterized a bifunctional glyoxylate cycle enzyme from E. gracilis (EgGCE). This enzyme consists of an N-terminal malate synthase (MS) domain fused to a C-terminal isocitrate lyase (ICL) domain in a single polypeptide chain. This domain order is inverted compared to the bifunctional glyoxylate cycle enzyme in Caenorhabditis elegans, an N-terminal ICL domain fused to a C-terminal MS domain. Purified EgGCE catalyzed the sequential ICL and MS reactions. ICL activity of purified EgGCE increased in the existence of acetyl-CoA at a concentration of micro-molar order. We discussed the physiological roles of the bifunctional glyoxylate cycle enzyme in these organisms as well as its molecular evolution. PMID:15964777

Nakazawa, Masami; Minami, Tomomi; Teramura, Koji; Kumamoto, Shohei; Hanato, Sayaka; Takenaka, Shigeo; Ueda, Mitsuhiro; Inui, Hiroshi; Nakano, Yoshihisa; Miyatake, Kazutaka

2005-08-01

155

Engineering Bifunctional Laccase-Xylanase Chimeras for Improved Catalytic Performance*  

PubMed Central

Two bifunctional enzymes exhibiting combined xylanase and laccase activities were designed, constructed, and characterized by biochemical and biophysical methods. The Bacillus subtilis cotA and xynA genes were used as templates for gene fusion, and the xynA coding sequence was inserted into a surface loop of the cotA. A second chimera was built replacing the wild-type xynA gene by a thermostable variant (xynAG3) previously obtained by in vitro molecular evolution. Kinetic measurements demonstrated that the pH and temperature optima of the catalytic domains in the chimeras were altered by less than 0.5 pH units and 5 °C, respectively, when compared with the parental enzymes. In contrast, the catalytic efficiency (kcat/Km) of the laccase activity in both chimeras was 2-fold higher than for the parental laccase. Molecular dynamics simulations of the CotA-XynA chimera indicated that the two domains are in close contact, which was confirmed by the low resolution structure obtained by small angle x-ray scattering. The simulation also indicates that the formation of the inter-domain interface causes the dislocation of the loop comprising residues Leu-558 to Lys-573 in the laccase domain, resulting in a more accessible active site and exposing the type I Cu2+ ion to the solvent. These structural changes are consistent with the results from UV-visible electronic and EPR spectroscopy experiments of the type I copper between the native and chimeric enzymes and are likely to contribute to the observed increase in catalytic turnover number.

Ribeiro, Lucas F.; Furtado, Gilvan P.; Lourenzoni, Marcos R.; Costa-Filho, Antonio J.; Santos, Camila R.; Nogueira, Simone C. Peixoto; Betini, Jorge A.; Polizeli, Maria de Lourdes T. M.; Murakami, Mario T.; Ward, Richard J.

2011-01-01

156

Transformation of phenol and its ethers in conditions of hydrogenation on bifunctional zeolite catalysts  

SciTech Connect

The reaction of hydrodimerization of phenol, anisole, and phenetole on bifunctional zeolite catalysts and the products and mechanism of the reaction were investigated. 2-Cyclohexylcyclohexanone is the basic product of the hydrodimerization of phenol, anisole, and phenetole in the presence of bifunctional zeolite catalysts containing palladium, nickel, rhodium, calcium, and lanthanum. The activity of the catalysts is a function of the type of cations added. Hydrodimerization of phenol and its ethers takes place through the stage of hydrogenation of the starting substances to cyclohexanone on metallic sites with subsequent condensation to 2-cyclohexylidenecyclohexane on acid sites and hydrogenation of the latter to 2-cyclohexylcyclohexanone.

Marchenko, L.S.; Levin, D.Z.; Plakhotnik, V.A.; Mortikov, E.S.

1986-07-10

157

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.

Choudhury, Jayati Roy; Bierbach, Ulrich

2005-01-01

158

Amos Bear Gets Hurt.  

ERIC Educational Resources Information Center

A three-day experiment set up by an early childhood teacher explored Piaget's view that children younger than age eight lack ability to take another's point of view. The experiment focused on a bear, the class mascot, and observations of children's empathetic behavior toward its "injury." Age-related differences in the children's responses were…

Read, Laurie

1995-01-01

159

High Performance Bearing Study.  

National Technical Information Service (NTIS)

A feasibility investigation was performed to identify the probable advantages, problem areas, and the degree of feasibility of applying air lubricated bearings to an advanced class of U.S. Air Force complex-cycle aircraft engines. Three P+WA engines incor...

W. D. Waldron W. E. Young

1972-01-01

160

Engine Hybrid Ceramic Bearings.  

National Technical Information Service (NTIS)

The objective of this program was the development of additional performance data and condition-monitoring techniques for silicon nitride (Si3N4) bearings. Induced-defect testing was performed to assess the ability of silicon nitride balls to withstand the...

M. Rhoads M. Bashyam

1994-01-01

161

Fluid Lubricated Bearing Assembly.  

National Technical Information Service (NTIS)

A support for a loaded rotatable shaft is described. The device consists of: a housing having a fluid-tight cavity encasing an end portion of the shaft; a thrust bearing near the open end of the cavity for supporting the axial thrust of the shaft, the thr...

H. A. Boorse G. F. Boeker J. R. Menke

1976-01-01

162

Axial Thrust Bearing.  

National Technical Information Service (NTIS)

The axial thrust bearing intended, for example, for a turbo-compressor used to supercharge an internal combustion engine, contains fixed and moving thrust elements in contact with the working shaft; it is distinguished by the fact that in order to increas...

L. A. Samarin S. T. Sharov V. A. Rakhmanov V. E. Vinyar Y. A. Trofimov

1971-01-01

163

Hybrid superconductor magnet bearings  

NASA Astrophysics Data System (ADS)

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

1995-04-01

164

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

165

Solving bearing overheating problems  

Microsoft Academic Search

Overheating is a major indicator, along with vibration and noise, of an underlying problem affecting a bearing or related components. Because normal operating temperatures vary widely from one application to another, no single temperature is a reliable sign of overheating in every situation. By observing an application when it is running smoothly, a technician can establish a benchmark temperature for

Jendzurski

1995-01-01

166

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

167

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

Code of Federal Regulations, 2011 CFR

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

2011-10-01

168

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

Code of Federal Regulations, 2012 CFR

...2012-10-01 false Who bears the burden of proof in a PIE proceeding? 40.385...Exclusions § 40.385 Who bears the burden of proof in a PIE proceeding? (a...the initiating official bears the burden of proof. (b) This burden is to...

2012-10-01

169

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

Code of Federal Regulations, 2010 CFR

...2009-10-01 2009-10-01 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...

2009-10-01

170

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

171

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

PubMed

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

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

172

Biomedical Applications of Gold Nanoparticles Functionalized Using Hetero-Bifunctional Poly(ethylene glycol) Spacer.  

National Technical Information Service (NTIS)

To increase the targeting potential, circulation time, and the flexibility of surface-attached biomedically-relevant ligands on gold nanoparticles, hetero-bifunctional poly(ethylene glycol) (PEG, MW 1,500) was synthesized having a thiol group on one termi...

W. Fu D. Shenoy J. Li C. Crasto G. Jones

2005-01-01

173

Highly enantioselective three-component direct Mannich reactions of unfunctionalized ketones catalyzed by bifunctional organocatalysts.  

PubMed

A highly stereoselective three-component direct Mannich reaction between aromatic aldehydes, p-toluenesulfonamide, and unfunctionalized ketones was achieved through an enolate mechanism for the first time with a bifunctional quinidine thiourea catalyst. The corresponding N-tosylated ?-aminoketones were obtained in high yields and excellent diastereo- and enantioselectivities (up to >99:1 dr and >99% ee). PMID:23343472

Guo, Qunsheng; Zhao, John Cong-Gui

2013-01-23

174

Efficient hydrodeoxygenation of biomass-derived ketones over bifunctional Pt-polyoxometalate catalyst.  

PubMed

Acidic heteropoly salt Cs(2.5)H(0.5)PW(12)O(40) doped with Pt nanoparticles is a highly active and selective catalyst for one-step hydrogenation of methyl isobutyl and diisobutyl ketones to the corresponding alkanes in the gas phase at 100 °C with 97-99% yield via metal-acid bifunctional catalysis. PMID:22684032

Alotaibi, Mshari A; Kozhevnikova, Elena F; Kozhevnikov, Ivan V

2012-06-11

175

Bifunctional titanocene catalysis in multicomponent couplings: a convergent assembly of ?-alkynyl ketones.  

PubMed

Herein is described a titanium-catalyzed three-component coupling to assemble ?-alkynyl ketones in a single operation. Treatment of an aryl aldehyde with an acetylide and silyl enol ether in the presence of a bifunctional titanocene catalyst enables the highly convergent assembly of ?-alkynyl ketones in good to excellent yields. PMID:23672573

Campos, Catherine A; Gianino, Joseph B; Ashfeld, Brandon L

2013-05-14

176

Pharmacokinetic Analysis of Two-Step Approaches Using Bifunctional and Enzyme-conjugatedAntibodies1  

Microsoft Academic Search

Bifunctional antibodies (BFA) and enzyme-conjugated antibodies (EGA) can be used to preferentially deliver a hapten or drug to tumor sites for diagnosis and therapy. We present here a simple pharmacoki- netic model for the above two systems by considering only two compart ments, the plasma and tumor. The models predict that the longer the time delay between the BFA and

Fan Yuan; Laurence T. Baxter; Rakesh K. Jain

1991-01-01

177

Sensitivity and Robustness in Covalent Modification Cycles with a Bifunctional Converter Enzyme  

PubMed Central

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

Straube, Ronny

2013-01-01

178

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

PubMed

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

Straube, Ronny

2013-10-15

179

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.

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

2000-01-01

180

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

Microsoft Academic Search

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

Guobao Chen; Huamin Zhang; Haipeng Ma; Hexiang Zhong

2009-01-01

181

Binuclear complexes of rhodium bridged by some new bifunctional anionic ligands  

NASA Astrophysics Data System (ADS)

Reaction of the binuclear complexes [Rh(?-Cl)(COD)] 2 with the bifunctional anionic 8-hydroxyquinolinate, 2-mercaptoquinolinate, and 2-hydroxysalicylaldiminate groups yields the binuclear complexes [Rh(?-XY)(COD)] 2, where XY - are the anionic groups listed. The complexes have been fully characterized by 1H and 13C NMR spectroscopy.

Al-Najjar, Ibrahim M.; Al-Hassan, Mohammed I.

1989-01-01

182

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

183

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

184

Bearing parameter identification of rotor-bearing system based on Kriging surrogate model and evolutionary algorithm  

NASA Astrophysics Data System (ADS)

Bearing dynamic parameters are important factors governing the vibration characteristics of rotating machinery, but they are usually unknown in the modeling. In this paper, an effective method is proposed to identify the bearing parameters and unbalance information of a rotor-bearing system based on the Kriging surrogate model and evolutionary algorithm (KSMEA). The initial Kriging surrogate model is constructed by the samples of various identification parameters (bearing parameters and magnitude of mass unbalance) and measured unbalance responses, which substitutes the original finite element model. It effectively reduces the computational expense of identification. In order to search for the global optimal solution exactly, one of the evolutionary algorithms, differential evolution (DE) algorithm is employed based on the constructed Kriging surrogate model. The effect on different numbers of samples is discussed to improve the accuracy of the Kriging surrogate model. Both numerical example and experimental results indicate that the proposed method can identify the bearing parameters and unbalance information of rotor-bearing system accurately and reliably.

Han, Fang; Guo, Xinglin; Gao, Haiyang

2013-05-01

185

Rotating plug bearing and seal  

DOEpatents

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

Wade, Elman E. (Ruffs Dale, PA)

1977-01-01

186

Bearing Race Support without Distortion.  

National Technical Information Service (NTIS)

A race for a bearing, which is mountable to a mount, has an annular bearing surface with a center axis defining an axis of rotation for the bearing and mutually perpendicular radial and transverse directions relative thereto. The race also has a radial wa...

D. A. Nyhus J. V. Alexander R. Soloski

2002-01-01

187

On Sandwiched Magnetic Bearing Design  

Microsoft Academic Search

This paper presents an innovative design for magnetic poles used in active magnetic bearings (AMBs). The proposed hybrid sandwiched magnetic pole design not only practically reduces the bearing size, but also dramatically diminishes its cost. The magnetic force to counterbalance the gravity of the rotor is provided by the embedded permanent magnets (PMs), while the electromagnetic bearing is merely used

Nan-Chyuan Tsai; Sheng-Liang Hsu

2007-01-01

188

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, âHow many polar bears are around the ice holes?â 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

189

Grizzly bears and forestry  

Microsoft Academic Search

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

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

2004-01-01

190

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

PubMed

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

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

2012-08-22

191

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

192

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

Microsoft Academic Search

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

A. K. Tieu; Z. L. Qiu

1995-01-01

193

VIBRATIONS OF HYBRID CERAMIC BALL BEARINGS  

Microsoft Academic Search

Hybrid ceramic ball bearings with silicone nitride balls and steel rings were tested, and the vibration characteristics were compared with those of conventional steel ball bearings. In this study, two types of hybrid ceramic ball bearings and two types of conventional steel ball bearings were used as test bearings. The test bearings were operated under several rotational speeds and axial

H. Ohta; K. Kobayashi

1996-01-01

194

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.

195

Bearing Dynamic Coefficients of Flexible-Pad Journal Bearings  

Microsoft Academic Search

The application of flexible-pad journal bearings for high-speed rotating machinery has recently gained attention from equipment manufacturers for its simplicity of one-piece design which can eliminate the manufacturing tolerance stack-up and possible lower functional power loss. This paper presents a general method for the calculation of bearing dynamic coefficients of flexible-pad journal bearings. These coefficients are critical to the rotor

Wen Jeng Chen

1995-01-01

196

Performance of an active electric bearing for rotary micromotors  

NASA Astrophysics Data System (ADS)

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

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

2011-08-01

197

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

198

Bears on Ice  

NSDL National Science Digital Library

Bears on Ice allows students to experience Antarctica through the eyes of two Geobears, Berkley and OzGold, who sailed on the Aurora Australis with their Australian friend and helper, Gordon Bain. These Bears have traveled to Antarctica and back and have had many adventures. They have brought back information and photographs that will help students share in their adventures. Links to more information and thinking questions are an integral part of this section. The Data pages contain numerical data about the voyage, such as the position of the ship (latitude and longitude) as well as many environmental conditions, like sea temperature, air temperature, or any ice that was encountered. The data lend themselves well to graphing and other math activities. The Information pages contain first-person accounts that go into more detail about some of their more exciting adventures, or ship procedures that need a bit more explanation than is offered in the daily reports. These, along with the linked Special Reports, can serve as reliable sources for research reports.

199

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

200

DEVELOPMENT OF A HYDROSTATIC JOURNAL BEARING WITH SLIT-STEP COMPENSATION  

SciTech Connect

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

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

2006-07-28

201

Mechanistic insights into the bifunctional non-heme iron oxygenase carbapenem synthase by active site saturation mutagenesis.  

PubMed

The carbapenem class of ?-lactam antibiotics is known for its remarkable potency, antibacterial spectrum, and resistance to ?-lactamase-mediated inactivation. While the biosynthesis of structurally "complex" carbapenems, such as thienamycin, share initial biochemical steps with carbapenem-3-carboxylate ("simple" carbapenem), the requisite inversion at C5 and formation of the characteristic ?,?-unsaturated carboxylate are different in origin between the two groups. Here, we consider carbapenem synthase, a mechanistically distinct bifunctional non-heme iron ?-ketoglutarate-dependent enzyme responsible for the terminal reactions, C5 epimerization and desaturation, in simple carbapenem production. Interestingly, this enzyme accepts two stereoisomeric substrates and transforms each to a common active antibiotic. Owing both to enzyme and product instability, resorting to saturation mutagenesis of active site and selected second-sphere residues gave clearly differing profiles of CarC tolerance to structural modification. Guided by a crystal structure and the mutational data, in silico docking was used to suggest the positioning of each disastereomeric substrate in the active site. The two orientations relative to the reactive iron-oxo center are manifest in the two distinct reactions, C5-epimerization and C2/3-desaturation. These observations favor a two-step reaction scheme involving two complete oxidative cycles as opposed to a single catalytic cycle in which an active site tyrosine, Tyr67, after hydrogen donation to achieve bicyclic ring inversion, is further hypothesized to serve as a radical carrier. PMID:23611403

Phelan, Ryan M; Townsend, Craig A

2013-05-13

202

Bifunctional unnatural sialic acids for dual metabolic labeling of cell-surface sialylated glycans.  

PubMed

Sialic acid analogues containing a unique chemical functionality or chemical reporter have been metabolically incorporated into sialylated glycans. This process, termed metabolic glycan labeling, has emerged as a powerful tool for studying sialylation as well as other types of glycosylation. Currently, this technique can install only a single functionality. Here we describe a strategy for dual labeling of sialylated glycans using a new class of bifunctional sialic acid analogues containing two distinct chemical reporters at the N-acyl and C9 positions. These bifunctional unnatural sialic acids were metabolically incorporated into cellular glycans, where the two chemical reporters exerted their distinct functions. This approach expands the capability of metabolic glycan labeling to probe sialylation and glycan-protein interactions. PMID:23725545

Feng, Lianshun; Hong, Senlian; Rong, Jie; You, Qiancheng; Dai, Peng; Huang, Rongbing; Tan, Yanhong; Hong, Weiyao; Xie, Can; Zhao, Jing; Chen, Xing

2013-06-14

203

New bifunctional anion-exchange resins for nuclear waste treatment: Part 2  

SciTech Connect

Additional bifunctional anion-exchange resins have been designed, synthesized and evaluated for their ability to take up Pu(IV) from nitric acid solutions. Bifunctionality is achieved by adding a second anion-exchange site to the pyridine nitrogen (also an anion-exchange site) of the base poly(4-vinylpyridine) resin. Previous work focused on the effect of varying the chemical properties of the added site along with the length of an alkylene spacer between the two sites. Here the authors examine four new 3- and 4-picolyl derivatives which maintain more rigidly defined geometries between the two nitrogen cationic sites. These materials, which have the two anion-exchange sites separated by three and four carbons, respectively, exhibit lower overall Pu(IV) distribution coefficients than the corresponding N-alkylenepyridium derivatives with more flexible spacers. Methylation of the second pyridium site results in a ca. 20% increase in the Pu(IV) distribution coefficients.

Marsh, S.F.; Jarvinen, G.D.; Barr, M.E. [Los Alamos National Lab., NM (United States); Bartsch, R.A. [Texas Tech Univ., Lubbock, TX (United States). Dept. of Chemistry and Biochemistry

1997-06-01

204

Sorption of Pu(IV) from nitric acid by bifunctional anion-exchange resins  

SciTech Connect

Anion exchange is attractive for separating plutonium because the Pu(IV) nitrate complex is very strongly sorbed and few other metal ions form competing anionic nitrate complexes. The major disadvantage of this process has been the unusually slow rate at which the Pu(IV) nitrate complex is sorbed by the resin. The paper summarizes the concept of bifunctional anion-exchange resins, proposed mechanism for Pu(IV) sorption, synthesis of the alkylating agent, calculation of K{sub d} values from Pu(IV) sorption results, and conclusions from the study of Pu(IV) sorption from 7M nitric acid by macroporous anion-exchange resins including level of crosslinking, level of alkylation, length of spacer, and bifunctional vs. monofunctional anion-exchange resins.

Bartsch, R.A.; Zhang, Z.Y.; Elshani, S.; Zhao, W. [Texas Tech Univ., Lubbock, TX (United States). Dept. of Chemistry and Biochemistry; Jarvinen, G.D.; Barr, M.E.; Marsh, S.F.; Chamberlin, R.M. [Los Alamos National Lab., NM (United States). Nuclear Materials Technology Div.

1999-06-01

205

Design and applications of bifunctional small molecules: Why two heads are better than one  

PubMed Central

Induction of protein-protein interactions is a daunting challenge, but recent studies show promise for small molecules that specifically bring two or more protein molecules together for enhanced or novel biological effect. The first such bifunctional molecules were the rapamycin- and FK506-based “Chemical Inducers of Dimerization”, but the field has since expanded with new molecules and new applications in chemical genetics and cell biology. Examples include coumermycin-mediated gyrase B dimerization, proteolysis targeting chimeric molecules (PROTACS), drug hybrids, and strategies for exploiting multivalency in toxin binding and antibody recruitment. This review discusses these and other advances in the design and use of bifunctional small molecules, and potential strategies for future systems.

Corson, Timothy W.; Aberle, Nicholas; Crews, Craig M.

2009-01-01

206

[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

207

Development of composite spherical bearing  

Microsoft Academic Search

Carbon–phenolic woven composite materials are employed in heavy-duty bearings due to their inherent self-lubricating properties and thermal stability. In this work, a composite spherical bearing (CSB) composed of carbon–phenolic composite race and steel ball is developed to solve the seizure of conventional metal–metal spherical bearings for the elevation driving mechanism (EDM) of a future battle tank. In order to eliminate

Byung Chul Kim; Dong Chang Park; Hak Sung Kim; Dai Gil Lee

2006-01-01

208

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

Microsoft Academic Search

A novel and efficient method has been developed for the synthesis of acid–base bifunctional catalyst SO3H–MCM-41–NH2. 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

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

2011-01-01

209

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

Microsoft Academic Search

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

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

2011-01-01

210

BIFUNCTIONAL Nb\\/Ti-MCM-41 CATALYST IN OXIDATIVE ACIDIC REACTION OF CYCLOHEXENE TO DIOL  

Microsoft Academic Search

Bifunctional oxidative and acidic catalyst was prepared by incorporating titanium ion (Ti4+) and niobic acid in mesoporous molecular sieves MCM -41 structure. The catalyst is active both in oxidation, and acid-catalyzed reaction of olefin to diol. Nb\\/Ti-MCM -41 catalyst was prepared by first synthesizing Ti-MCM -41 by hydrothermal method, followed by subsequent impregnation of niobic acid (Nb) into Ti-MCM -41

Zainab Ramli; Mazidah Abdul Shukor; Didik Prasetyoko

211

Bifunctional phosphoglucose\\/phosphomannose isomerase from the hyperthermophilic archaeon Pyrobaculum aerophilum  

Microsoft Academic Search

ORF PAE1610 from the hyperthermophilic crenarchaeon Pyrobaculum aerophilum was first annotated as the conjectural pgi gene coding for hypothetical phosphoglucose isomerase (PGI). However, we have recently identified this ORF as the putative pgi\\/pmi gene coding for hypothetical bifunctional phosphoglucose\\/phosphomannose isomerase (PGI\\/PMI). To prove its coding function, ORF PAE1610 was overexpressed in Escherichia coli, and the recombinant enzyme was characterized. The

Thomas Hansen; Claus Urbanke; Peter Schönheit

2004-01-01

212

Molecular characterization of a bifunctional glyoxylate cycle enzyme, malate synthase\\/isocitrate lyase, in Euglena gracilis  

Microsoft Academic Search

Euglena gracilis induced glyoxylate cycle enzymes when ethanol was fed as a sole carbon source. We purified, cloned and characterized a bifunctional glyoxylate cycle enzyme from E. gracilis (EgGCE). This enzyme consists of an N-terminal malate synthase (MS) domain fused to a C-terminal isocitrate lyase (ICL) domain in a single polypeptide chain. This domain order is inverted compared to the

Masami Nakazawa; Tomomi Minami; Koji Teramura; Shohei Kumamoto; Sayaka Hanato; Shigeo Takenaka; Mitsuhiro Ueda; Hiroshi Inui; Yoshihisa Nakano; Kazutaka Miyatake

2005-01-01

213

Construction and Evaluation of a Novel Bifunctional N-Carbamylase-D-Hydantoinase Fusion Enzyme  

Microsoft Academic Search

A fully enzymatic process employing two sequential enzymes, D-hydantoinase and N-carbamylase, is a typical case requiring combined enzyme activity for the production of D-amino acids. To test the possibility of generating a bifunctional fusion enzyme, we constructed a fusion protein via end-to-end fusion of a whole gene that encodes an intact protein at the N terminus of the D-hydantoinase. Firstly,

GEUN-JOONG KIM; DONG-EUN LEE; HAK-SUNG KIM

2000-01-01

214

On the structure of poly- ?-caprolactams, obtained with bifunctional N-carbamyl derivatives of lactams  

Microsoft Academic Search

The present study deals with the structures of poly (?-caprolactams), (PA-6), obtained by anionic ‘pseudoliving’ polymerization in bulk in the presence of bifunctional N-carbamyl lactams as activators (AC): (1) Hexamethylen di-carbamyl di-caprolactam (C-X); (2) 3,3,5 trimethyl-5 methyl cyclohexyl di-carbamyl di-caprolactam (C-I). The physical behavior of PA-6 samples synthesized at various polymerization conditions were studied by DSC, IR, WAXD and thermomechanical

R. Mateva; P. Petrov; S. Rousseva; R. Dimitrov; G. Zolova

2000-01-01

215

NAD(H) recycling activity of an engineered bifunctional enzyme galactose dehydrogenase\\/lactate dehydrogenase  

Microsoft Academic Search

A chimeric bifunctional enzyme composing of galactose dehydrogenase (galDH; from Pseudomonas fluorescens) and lactate dehydrogenase (LDH; from Bacillus stearothermophilus) was successfully constructed. The chimeric galDH\\/LDH possessed dual characteristics of both galactose dehydrogenase and lactate dehydrogenase activities while exhibiting hexameric rearrangement with a molecular weight of approximately 400 kDa. In vitro observations showed that the chimeric enzyme was able to recycle

Virapong Prachayasittikul; Sarah Ljung; Chartchalerm Isarankura-Na-Ayudhya; Leif Bülow

2006-01-01

216

Isolation of the bifunctional enzyme lysine 2-oxoglutarate reductase-saccharopine dehydrogenase from Phaseolus vulgaris  

Microsoft Academic Search

Summary.  ?Lysine is catabolyzed by the bifunctional enzyme lysine 2-oxoglutarate reductase-saccharopine dehydrogenase (LOR-SDH) in\\u000a both animals and plants. LOR condenses lysine and 2-oxoglutarate into saccharopine, using NADPH as cofactor and SDH converts\\u000a saccharopine into ?-aminoadipate ?-semialdehyde and glutamic acid, using NAD as cofactor. The distribution pattern of LOR and SDH among different tissues of\\u000a Phaseolus vulgaris was determined. The hypocotyl contained

S. T. Cunha Lima; R. A. Azevedo; L. G. Santoro; S. A. Gaziola; P. J. Lea

2003-01-01

217

Enantioselective, Organocatalytic Reduction of Ketones using Bifunctional Thiourea-Amine Catalysts  

PubMed Central

Prochiral ketones are reduced to enantioenriched, secondary alcohols using catecholborane and a family of air-stable, bifunctional thiourea-amine organocatalysts. Asymmetric induction is proposed to arise from the in situ complexation between the borane and chiral thiourea-amine organocatalyst resulting in a stereochemically biased boronate-amine complex. The hydride in the complex is endowed with enhanced nucleophilicity while the thiourea concomitantly embraces and activates the carbonyl.

Li, De Run; He, Anyu; Falck, J. R.

2010-01-01

218

Bifunctional mesoporous organic–inorganic hybrid silica for combined one-step hydrogenation\\/esterification  

Microsoft Academic Search

Bifunctional mesoporous organic–inorganic hybrid silicas with platinum and propylsulfonic acid group (Pt\\/SBA15-PrSO3H) were synthesized and tested for the combined one-step hydrogenation\\/esterification (OHE) reaction, which was employed as a model reaction for catalytic upgrading of biomass-derived bio-oil. The model reagents used were acetic acid and acetaldehyde. Different catalyst synthesis procedures were investigated and compared by varying the functional group incorporation method,

Yang Tang; Shaojun Miao; Brent H. Shanks; Xiaoming Zheng

2010-01-01

219

Structural and transcriptional analysis of plant genes encoding the bifunctional lysine ketoglutarate reductase saccharopine dehydrogenase enzyme  

Microsoft Academic Search

BACKGROUND: Among the dietary essential amino acids, the most severely limiting in the cereals is lysine. Since cereals make up half of the human diet, lysine limitation has quality\\/nutritional consequences. The breakdown of lysine is controlled mainly by the catabolic bifunctional enzyme lysine ketoglutarate reductase - saccharopine dehydrogenase (LKR\\/SDH). The LKR\\/SDH gene has been reported to produce transcripts for the

Olin D Anderson; Devin Coleman-Derr; Yong Q Gu; Sekou Heath

2010-01-01

220

Facile one-pot synthesis of gold nanoparticles stabilized with bifunctional amino\\/siloxy ligands  

Microsoft Academic Search

A method for the direct one-pot synthesis of amine-stabilized gold nanoparticles using 3-(trimethoxysilylpropyl)diethylenetriamine (TMSP dien) is described. The amine groups of this bifunctional molecule act as a stabilizer for gold nanoparticles as they form by reduction of HAuCl4. Highly stable gold nanoparticles with sizes tunable between 8 and 20 nm can be readily obtained. This method is quite simple to

Haoguo Zhu; Zhengwei Pan; Edward W. Hagaman; Chengdu Liang; Steven H. Overbury; Sheng Dai

2005-01-01

221

Crystal structure of the membrane-bound bifunctional transglycosylase PBP1b from Escherichia coli  

Microsoft Academic Search

Drug-resistant bacteria have caused serious medical problems in recent years, and the need for new antibacterial agents is undisputed. Transglycosylase, a multidomain membrane protein essential for cell wall synthesis, is an excellent target for the development of new antibiotics. Here, we determined the X-ray crystal structure of the bifunctional transglycosylase penicillin-binding protein 1b (PBP1b) from Escherichia coli in complex with

Ming-Ta Sung; Yen-Ting Lai; Chia-Ying Huang; Lien-Yang Chou; Hao-Wei Shih; Wei-Chieh Cheng; Chi-Huey Wong; Che Ma

2009-01-01

222

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

Microsoft Academic Search

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

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

2006-01-01

223

Electrochemical studies of Pt\\/Ir–IrO 2 electrocatalyst as a bifunctional oxygen electrode  

Microsoft Academic Search

In the present study, Ir nanoparticles are deposited on the surface of IrO2 nanoparticles with microwave-assisted polyol process. Then the obtained Ir–IrO2 nanocomposite is used as a support to prepare Pt\\/Ir–IrO2 nanocomposite, which has been demonstrated as an excellent bifunctional oxygen catalyst for unitized regenerative fuel cell. X-ray diffraction (XRD), X-ray photoelectron spectra (XPS), and transmission electron microscopy (TEM) characterizations

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

224

Development of a pair of bifunctional expression vectors for Escherichia coli and Bacillus licheniformis  

Microsoft Academic Search

A pair of bifunctional expression vectors, pBL-WZX and pHY-WZX, for Escherichia coli and Bacillus licheniformis was constructed to express interesting genes in a secretory manner. The vectors contain an expression cassette consisted\\u000a of the promoter and signal peptide region of B. licheniformis amyL as well as an artificial multiple cloning site and a terminator and utilize kanamycin-resistance and\\/or tetracycline-resistance\\u000a for

Dandan Niu; Zheng-Xiang Wang

2007-01-01

225

Approaches Toward Synthesizing Novel Extractant Systems: Polymeric Bifunctional Extractants with Synergistic Possibilities  

Microsoft Academic Search

The synthesis of a monoarylphosphinic acid-diarylphosphine oxide extractant system supported on macroporous polystyrene beads is reported. The bifunctional resin was used in separate zinc and copper(I1) ion extraction studies. Results wth both metals show an excellent extent of extraction under low loading conditions and solution pH of 1–2; at equivalent meta1:resin concentrations, the resin absorbs 50% of the metalin solution.

S. D. Alexandratos; W. J. McDowell

1983-01-01

226

Enhanced sulfur resistance of bifunctional Pd\\/HZSM-5 catalyst comprising hierarchical carbon-templated zeolite  

Microsoft Academic Search

A bifunctional hierarchical micro-mesoporous Pd\\/HZSM-5-BP catalyst (2wt% Pd) has been prepared by impregnating an HZSM-5 sample hydrothermally synthesized in the presence of nearly uniform carbon nanoparticles (Black Pearls 2000) of ca. 12nm in size in order to generate intracrystalline mesovoids (mostly in the 10–20nm range, as ascertained by TEM). An equivalent catalyst (Pd\\/HZSM-5-ref) comprising an HZSM-5 zeolite having roughly the

A. Martínez; M. A. Arribas; M. Derewinski; A. Burkat-Dulak

2010-01-01

227

Research Trends on Magnetic Bearings  

NASA Astrophysics Data System (ADS)

Use of magnetic bearings for high-speed rotor and application in clean environment or in special circumstance have been gradually increasing. This article overviews research trends and application presented before the Eighth International Symposium on Magnetic Bearings (ISMB-8). Interesting research topics are the combined realization of motor and magnetic bearing, low loss magnetic bearings and self-sensing techniques. New application fields include small spindles for data storage devices, energy storage flywheels, and artificial heart pumps. Various new technologies are reported related to these new application fields.

Okada, Yohji; Nonami, Kenzo

228

A Processive Carbohydrate Polymerase That Mediates Bifunctional Catalysis Using a Single Active Site  

PubMed Central

Even in the absence of a template, glycosyltransferases can catalyze the synthesis of carbohydrate polymers of specific sequence. The paradigm has been that one enzyme catalyzes the formation of one type of glycosidic linkage, yet certain glycosyltransferases generate polysaccharide sequences composed of two distinct linkage types. In principle, bifunctional glycosyltransferases can possess separate active sites for each catalytic activity or one active site with dual activities. We encountered the fundamental question of one or two distinct active sites in our investigation of the galactosyltransferase GlfT2. GlfT2 catalyzes the formation of mycobacterial galactan, a critical cell-wall polymer composed of galactofuranose residues connected with alternating, regioisomeric linkages. We found that GlfT2 mediates galactan polymerization using only one active site that manifests dual regioselectivity. Structural modeling of the bifunctional glycosyltransferases hyaluronan synthase and cellulose synthase suggests that these enzymes also generate multiple glycosidic linkages using a single active site. These results highlight the versatility of glycosyltransferases for generating polysaccharides of specific sequence. We postulate that a hallmark of processive elongation of a carbohydrate polymer by a bifunctional enzyme is that one active site can give rise to two separate types of glycosidic bonds.

May, John F.; Levengood, Matthew R.; Splain, Rebecca A.; Brown, Christopher D.; Kiessling, Laura L.

2012-01-01

229

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

PubMed Central

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

Tircso, Gyula; Benyo, Eniko Tircsone; Suh, Eul Hyun; Jurek, Paul; Kiefer, Garry E.; Sherry, A. Dean; Kovacs, Zoltan

2009-01-01

230

Primary structure of the gene encoding the bifunctional dihydrofolate reductase-thymidylate synthase of Leishmania major.  

PubMed Central

We have determined the nucleotide sequence of the dihydrofolate reductase-thymidylate synthetase (DHFR-TS) gene of the protozoan parasite Leishmania major (dihydrofolate reductase, EC 1.5.1.3 and thymidylate synthase, EC 2.1.1.45). The DHFR-TS protein is encoded by a single 1560-base-pair open reading frame within genomic DNA, in contrast to vertebrate DHFRs or mouse and phage T4 TSs, which contain intervening sequences. Comparisons of the DHFR-TS sequence with DHFR and TS sequences of other organisms indicate that the order of enzymatic activities within the bifunctional polypeptide chain is DHFR followed by TS, the Leishmania bifunctional DHFR-TS evolved independently and not through a phage T4-related intermediate, and the rate of evolution of both the DHFR and TS domains has not detectably changed despite the acquisition of new functional properties by the bifunctional enzyme. The Leishmania gene is 86% G+C in the third codon position, in contrast to genes of the parasite Plasmodium falciparum, which exhibit an opposite bias toward A+T. The DHFR-TS locus is encoded within a region of DNA amplified in methotrexate-resistant lines, as previously proposed.

Beverley, S M; Ellenberger, T E; Cordingley, J S

1986-01-01

231

NASA Antenna Gets its Bearings  

NASA Video Gallery

The historic "Mars antenna" at NASA's Deep Space Network site in Goldstone, Calif. has finished a major, delicate surgery that lasted seven months. The operation on the giant, 70-meter-wide (230-foot) antenna replaced the hydrostatic bearing assembly, which enables the antenna to rotate horizontally, and the elevation bearings, which enable the antenna to track up and down from the horizon.

Luis Espinoza

2010-11-01

232

The Migration of Polar Bears.  

National Technical Information Service (NTIS)

As the polar bear roams widely over its Arctic habitat in quest of its principal food--seal meat, little is known about him. Now a technique is at hand that promises to fill some of the gaps in our knowledge of the polar bear's life. The technique involve...

V. Flyger M. R. Townsend

1968-01-01

233

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

234

GEOPHAGY BY YELLOWSTONE GRIZZLY BEARS  

Microsoft Academic Search

We documented 12 sites in the Yellowstone ecosystem where grizzly bears (Ursus arctos horribilis) had purposefully consumed soil (an activity known as geophagy). We also documented soil in numerous grizzly bear feces. Geophagy primarily occurred at sites barren of vegetation where surficial geology had been modified by geothermal activity. There was no evidence of ungulate use at most sites. Purposeful

GERALD I. GREEN; ROGER SWALLEY

235

Teflon-Lined Bearing Improvement.  

National Technical Information Service (NTIS)

The patent application describes a method of repairing or retrofitting the teflon fabric liner of a spherical and/or self-aligning bearing, that has separated due to poor bonding with the bearing surface, with a metal-backed, teflon liner that includes a ...

P. R. Eklund

1972-01-01

236

Geophagy by yellowstone grizzly bears  

USGS Publications Warehouse

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

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

1999-01-01

237

Synthesis and evaluation of novel bifunctional chelating agents based on 1,4,7,10-tetraazacyclododecane-N,N',N",N"'-tetraacetic acid for radiolabeling proteins.  

PubMed

Detailed synthesis of the bifunctional chelating agents 2-methyl-6-(p-isothiocyanatobenzyl)-1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (1B4M-DOTA) and 2-(p-isothiocyanatobenzyl)-5, 6-cyclohexano-1, 4, 7, 10-tetraazacyclododecane-1, 4, 7, 10-tetraacetate (CHX-DOTA) are reported. These chelating agents were compared to 2-(p-isothiocyanatobenzyl)-1, 4, 7, 10-tetraazacyclododecane-1, 4, 7, 10-tetraacetic acid (C-DOTA) and 1, 4, 7, 10-Tetraaza-N-(1-carboxy-3-(4-nitrophenyl)propyl)-N', N", N"'-tris(acetic acid) cyclododecane (PA-DOTA) as their (177)Lu radiolabeled conjugates with Herceptin. In vitro stability of the immunoconjugates radiolabeled with (177)Lu was assessed by serum stability studies. The in vivo stability of the radiolabeled immunoconjugates and their targeting characteristics were determined by biodistribution studies in LS-174T xenograft tumor-bearing mice. Relative radiolabeling rates and efficiencies were determined for all four immunoconjugates. Insertion of the 1B4M moiety into the DOTA backbone increases radiometal chelation rate and provides complex stability comparable to C-DOTA and PA-DOTA while the CHX-DOTA appears to not form as stable a (177)Lu complex while exhibiting a substantial increase in formation rate. The 1B4M-DOTAmay have potential for radioimmunotherapy applications. PMID:12900284

Chappell, L L; Ma, D; Milenic, D E; Garmestani, K; Venditto, V; Beitzel, M P; Brechbiel, M W

2003-08-01

238

Thermally Activated Seizure of Angular Contact Bearings  

Microsoft Academic Search

Equations have been developed relating friction-power to bearing element temperatures for the particular case of prelubricated or lightly lubricated ball bearings. An expression is derived for the change in relative dimensions of an angular contact bearing, as determined by the temperature gradient across the bearing. A second expression is found for the accommodation of the bearing to expansion, this accommodation

R. A. Burton; H. E. Staph

1967-01-01

239

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

Federal Register 2010, 2011, 2012, 2013

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

2012-11-26

240

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

PubMed Central

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

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

2012-01-01

241

Effects of bearing cleaning and lube environment on bearing performance  

NASA Astrophysics Data System (ADS)

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

Ward, Peter C.

1995-05-01

242

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

PubMed

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

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

2009-03-01

243

Purification and Characterization of Bifunctional Lysine-Ketoglutarate Reductase/Saccharopine Dehydrogenase from Developing Soybean Seeds1  

PubMed Central

Both in mammals and plants, excess lysine (Lys) is catabolized via saccharopine into ?-amino adipic semialdehyde and glutamate by two consecutive enzymes, Lys-ketoglutarate reductase (LKR) and saccharopine dehydrogenase (SDH), which are linked on a single bifunctional polypeptide. To study the control of metabolite flux via this bifunctional enzyme, we have purified it from developing soybean (Glycine max) seeds. LKR activity of the bifunctional LKR/SDH possessed relatively high Km for its substrates, Lys and ?-ketoglutarate, suggesting that this activity may serve as a rate-limiting step in Lys catabolism. Despite their linkage, the LKR and SDH enzymes possessed significantly different pH optima, suggesting that SDH activity of the bifunctional enzyme may also be rate-limiting in vivo. We have previously shown that Arabidopsis plants contain both a bifunctional LKR/SDH and a monofunctional SDH enzymes (G. Tang, D. Miron, J.X. Zhu-Shimoni, G. Galili [1997] Plant Cell 9: 1–13). In the present study, we found no evidence for the presence of such a monofunctional SDH enzyme in soybean seeds. These results may provide a plausible regulatory explanation as to why various plant species accumulate different catabolic products of Lys.

Miron, Daphna; Ben-Yaacov, Sari; Reches, Dalit; Schupper, Avigail; Galili, Gad

2000-01-01

244

Thermal Interactions in Rolling Bearing Dynamics.  

National Technical Information Service (NTIS)

Numerical enhancements to the established bearing dynamics computer code, Advanced Dynamics of Rolling Elements (ADORE), have been accomplished for improved computation of bearing heat generation and geometrical variation in bearing element dimensions. Th...

P. K. Gupta

2002-01-01

245

Labeling Biomolecules with Radiorhenium - a Review of the Bifunctional Chelators  

PubMed Central

For radiotherapy, biomolecules such as intact antibodies, antibody fragments, peptides, DNAs and other oligomers have all been labeled with radiorhenium (186Re and 188Re). Three different approaches have been employed that may be referred to as direct, indirect and integral labeling. Direct labeling applies to proteins and involves the initial reduction of endogenous disulfide bridges to provide chelation sites. Indirect labeling can apply to most biomolecules and involves the initial attachment of an exogenous chelator. Finally, integral labeling is a special case applying only to small molecules in which the metallic radionuclide serves to link two parts of a biomolecule together in forming the labeled complex. While the number of varieties for the direct and integral radiolabeling approaches is rather limited, a fairly large and diverse number of chelators have been reported in the case of indirect labeling. Our objective herein is to provide an overview of the various chelators that have been used in the indirect labeling of biomolecules with radiorhenium, including details on the labeling procedures, the stability of the radiolabel and, where possible, the influence of the label on biological properties.

Liu, Guozheng; Hnatowich, Donald J.

2007-01-01

246

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

247

Mechanistic and structural analysis of aminoglycoside N-acetyltransferase AAC(6')-Ib and its bifunctional, fluoroquinolone-active AAC(6')-Ib-cr variant.  

PubMed

Enzymatic modification of aminoglycoside antibiotics mediated by regioselective aminoglycoside N-acetyltransferases is the predominant cause of bacterial resistance to aminoglycosides. A recently discovered bifunctional aminoglycoside acetyltransferase (AAC(6')-Ib variant, AAC(6')-Ib-cr) has been shown to catalyze the acetylation of fluoroquinolones as well as aminoglycosides. We have expressed and purified AAC(6')-Ib-wt and its bifunctional variant AAC(6')-Ib-cr in Escherichia coli and characterized their kinetic and chemical mechanism. Initial velocity and dead-end inhibition studies support an ordered sequential mechanism for the enzyme(s). The three-dimensional structure of AAC(6')-Ib-wt was determined in various complexes with donor and acceptor ligands to resolutions greater than 2.2 A. Observation of the direct, and optimally positioned, interaction between the 6'-NH 2 and Asp115 suggests that Asp115 acts as a general base to accept a proton in the reaction. The structure of AAC(6')-Ib-wt permits the construction of a molecular model of the interactions of fluoroquinolones with the AAC(6')-Ib-cr variant. The model suggests that a major contribution to the fluoroquinolone acetylation activity comes from the Asp179Tyr mutation, where Tyr179 makes pi-stacking interactions with the quinolone ring facilitating quinolone binding. The model also suggests that fluoroquinolones and aminoglycosides have different binding modes. On the basis of kinetic properties, the pH dependence of the kinetic parameters, and structural information, we propose an acid/base-assisted reaction catalyzed by AAC(6')-Ib-wt and the AAC(6')-Ib-cr variant involving a ternary complex. PMID:18710261

Vetting, Matthew W; Park, Chi Hye; Hegde, Subray S; Jacoby, George A; Hooper, David C; Blanchard, John S

2008-08-19

248

In vivo evaluation of a radiogallium-labeled bifunctional radiopharmaceutical, Ga-DOTA-MN2, for hypoxic tumor imaging.  

PubMed

On the basis of the findings obtained by X-ray crystallography of Ga-DOTA chelates and the drug design concept of bifunctional radiopharmaceuticals, we previously designed and synthesized a radiogallium-labeled DOTA chelate containing two metronidazole moieties, (67)Ga-DOTA-MN2, for hypoxic tumor imaging. As expected, (67)Ga-DOTA-MN2 exhibited high in vivo stability, although two carboxyl groups in the DOTA skeleton were conjugated with metronidazole moieties. In this study, we evaluated (67/68)Ga-DOTA-MN2 as a nuclear imaging agent for hypoxic tumors. (67)Ga-labeling of DOTA-MN2 with (67)GaCl(3) was achieved with high radiochemical yield (>85%) by 1-min of microwave irradiation (50 W). The pharmacokinetics of (67)Ga-DOTA-MN2 were examined in FM3A tumor-bearing mice, and compared with those of (67)Ga-DOTA-MN1 containing one metronidazole unit and (67)Ga-DOTA. Upon administration, (67)Ga-DOTA-MN2 exhibited higher accumulation in the implanted tumors than (67)Ga-DOTA. Tumor-to-blood ratios of (67)Ga-DOTA-MN2 were about two-fold higher than those of (67)Ga-DOTA-MN1. Autoradiographic analysis showed the heterogeneous localization of (67)Ga-DOTA-MN2 in the tumors, which corresponds to hypoxic regions suggested by well-established hypoxia marker drug, pimonidazole. Furthermore, in positron emission tomography (PET) study, the tumors of mice administered (68)Ga-labeled DOTA-MN2 were clearly imaged by small-animal PET at 1 h after administration. This study demonstrates the potential usefulness of (67/68)Ga-DOTA-MN2 as a nuclear imaging agent for hypoxic tumors and suggests that two functional moieties, such as metronidazole, can be conjugated to radiogallium-DOTA chelate without reducing the complex stability. The present findings provide useful information about the chemical design of radiogallium-labeled radiopharmaceuticals for PET and single photon emission computed tomography (SPECT) studies. PMID:23546294

Sano, Kohei; Okada, Mayumi; Hisada, Hayato; Shimokawa, Kenta; Saji, Hideo; Maeda, Minoru; Mukai, Takahiro

2013-01-01

249

Multivalent Bifunctional Chelator Scaffolds for Gallium-68 Based Positron Emission Tomography Imaging Probe Design: Signal Amplification via Multivalency  

PubMed Central

The role of the multivalent effect has been well recognized in the design of molecular imaging probes towards the desired imaging signal amplification. Recently we reported a bifunctional chelator (BFC) scaffold design, which provides a simple and versatile approach to impart multivalency to radiometal based nuclear imaging probes. In this work, we report a series of BFC scaffolds (tBu3-1-COOH, tBu3-2-(COOH)2 and tBu3-3-(COOH)3) constructed on the framework of 1,4,7-triazacyclononane-1,4,7-triacetic acid (NOTA) for 68Ga-based PET probe design and signal amplification via multivalent effect. For proof of principle, a known integrin ?v?3 specific ligand (c(RGDyK)) was used to build the corresponding NOTA conjugates (H31, H32, and H33), which present 1 – 3 copies of c(RGDyK) peptide, respectively, in a systematic manner. Using the integrin ?v?3 binding affinities (IC50 values), the enhanced specific binding was observed for multivalent conjugates (H32: 43.9 ± 16.1 nM; H33: 14.7 ± 5.0 nM) as compared to their monovalent counterpart (H31: 171 ± 60 nM) and the intact c(RGDyK) peptide (204 ± 76 nM). The obtained conjugates were efficiently labeled with 68Ga3+ within 30 min at room temperature in high radiochemical yields (> 95%). The in vivo evaluation of the labeled conjugates, 68Ga-1, 68Ga-2 and 68Ga-3, was performed using male severe combined immunodeficiency (SCID) mice bearing integrin ?v?3 positive PC-3 tumor xenografts (n = 3). All 68Ga -labeled conjugates showed high in vivo stability with no detectable metabolites found by radio-HPLC within 2 h post-injection (p.i.). The PET signal amplification in PC-3 tumor by multivalent effect was clearly displayed by the tumor uptake of the 68Ga-labeled conjugates (68Ga-3: 2.55 ± 0.50%ID/g; 68Ga-2: 1.90 ± 0.10 %ID/g; 68Ga-1: 1.66 ± 0.15 %ID/g) at 2 h p.i. In summary, we have designed and synthesized a series of NOTA-based BFC scaffolds with signal amplification properties, which may find potential applications in diagnostic gallium radiopharmaceuticals.

Singh, Ajay N.; Liu, Wei; Hao, Guiyang; Kumar, Amit; Gupta, Anjali; Oz, Orhan K.; Hsieh, Jer-Tsong; Sun, Xiankai

2011-01-01

250

HOME RANGE AND MOVEMENTS OF WINTER-ACTIVE BLACK BEARS IN THE GREAT DISMAL SWAMP  

Microsoft Academic Search

During May 1984, we initiated a study of black bear (Ursus americanus) ecology on the 410 km2 Great Dismal Swamp Wildlife Refuge, a forested wetland in eastern Virginia and North Carolina. Two male bears (ages 3 and 4) and 2 females (ages 3 and 7) remained active during winter 1984-85. Eight other bears (5 males, 3 females) denned for 70-131

ERIC C. HELLGREN; MICHAEL R. VAUGHAN

251

An apparatus for bearing-bypass testing of bolted joints  

SciTech Connect

A dual-control test system measuring the strength of graphite/epoxy specimens under tension and compression for a wide range of bearing-bypass load ratios is presented. The bearing-bypass strengths of single-fastener specimens are measured for damage onset and ultimate failure and are plotted against one another. The results indicate that an initiated damage grows to failure in the same mode for most cases. However, if the damage is initiated in the compression-reacted-bearing mode, the specimens fail in the offset-compression mode. It is concluded that this type of transition can occur in multi-fastener joints under compression and complicate the strength predictions. 12 refs.

Crews, J.H. Jr. (NASA, Langley Research Center, Hampton, VA (USA))

1990-12-01

252

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

253

Ceramic Gas Bearing Material Evaluation.  

National Technical Information Service (NTIS)

Flat washer specimens were experimentally tested under conditions simulating start-stop and continuous rubbing contact of a gas-lubricated thrust bearing. Minimum surface damage with a constant and low value of the friction coefficient were criteria for j...

J. T. McCabe P. R. Albrecht E. F. Finkin

1972-01-01

254

Yellowstone Grizzly Bear Investigations 2000.  

National Technical Information Service (NTIS)

It was recognized as early as 1973, that in order to understand the dynamics of grizzly bears (Ursus arctos horribilis) throughout the Greater Yellowstone Ecosystem (GYE), there was a need for a centralized research group responsible for collecting, manag...

C. C. Schwartz M. A. Haroldson

2001-01-01

255

Yellowstone Grizzly Bear Investigations 1999.  

National Technical Information Service (NTIS)

It was recognized as early as 1973, that in order to understand the dynamics of grizzly bears (Ursus arctos horribilis) throughout the Greater Yellowstone Area, there was a need for a centralized research group responsible for collecting, managing, analyz...

C. C. Schwartz M. A. Haroldson

2000-01-01

256

Myrmecophagy by Yellowstone grizzly bears  

USGS Publications Warehouse

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

Mattson, D. J.

2001-01-01

257

Lateral Dampers for Thrust Bearings.  

National Technical Information Service (NTIS)

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 cons...

D. H. Hibner D. R. Szafir

1985-01-01

258

Bearing capacity of desiccated tailings  

SciTech Connect

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 respect to matric suction is established by testing reconstituted tailings samples in a modified triaxial cell, in which matric suction can be controlled. The contribution of matric suction to the shear strength is interpreted as an additional apparent cohesion for use in bearing-capacity calculations. Because of the nonlinearity of the shear-strength profile, a numerical method of analysis is adopted to predict the ultimate bearing capacity of the desiccated tailings. A subsequent decrease in bearing capacity following 2D water infiltration into a partially capped tailings deposit and accompanying suction loss is investigated.

Rassam, D.W.; Williams, D.J. [Univ. of Queensland, Brisbane, Queensland (Australia). Dept. of Civil Engineering

1999-07-01

259

Evaluation of Shuttle Turbopump Bearings.  

National Technical Information Service (NTIS)

Because the high pressure turbopumps used on the space shuttle main engine (SSME) are high speed machines and rotor dynamics analysis of these units is very complicated, it was considered necessary to verify calculated turbomachinery shaft bearing loads b...

K. D. Dufrane J. W. Kannel

1978-01-01

260

CCPI bears first fruit  

SciTech Connect

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

Wicker, K.

2006-01-15

261

Superconducting composite for magnetic bearings  

SciTech Connect

A composite includes granules of Type II superconducting material and granules of rare-earth permanent magnets that are distributed in a binder. The composite is a two-phase structure that combines the properties of the superconductor and magnets with the flexibility and toughness of a polymeric material. A bearing made from this composite has the load capacity and stiffness of a permanent magnet bearing with added stability from a Type II superconducting material. 7 figs.

Rigney, T.K. II

1995-10-10

262

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.

2009-04-01

263

Photoaffinity labelling of lactate dehydrogenase from pig heart with a bifunctional NAD +-analogue  

Microsoft Academic Search

P1-N6-(4-azidophenylethyl)adenosine-P2-4-(3-azidopyridinio)butyl diphosphate was synthesized with an [8-14C]adenine label. This bifunctional photoaffinity labelling reagent inactivates lactate dehydrogenase from pig heart upon irradiation with light of wavelength 300–380 nm. Stoichiometry of binding and enzymatic parameters suggest that the analogue is bound to the coenzyme binding site and that adjacent residues are modified. Four radioactive peptides were isolated by reverse-phase HPLC after tryptic

Susanne Becker; Tomas Bergman; Lars Hjelmqvist; Reinhard Jeck; Hans Jörnvall; Hanno Leibrock; Christoph Woenckhaus

1996-01-01

264

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

PubMed

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

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

2012-11-21

265

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

PubMed

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

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

2008-03-10

266

Facile one-pot synthesis of gold nanoparticles stabilized with bifunctional amino/siloxy ligands  

SciTech Connect

A method for the direct one-pot synthesis of amine-stabilized gold nanoparticles using 3-(trimethoxysilylpropyl)diethylenetriamine (TMSP dien) is described. The amine groups of this bifunctional molecule act as a stabilizer for gold nanoparticles as they form by reduction of HAuCl{sub 4}. Highly stable gold nanoparticles with sizes tunable between 8 and 20 nm can be readily obtained. This method is quite simple to implement and environmentally benign as there is no need to add an external reducing reagent. The incorporated siloxy functionality was subsequently used to form a silica shell around the gold particle.

Zhu, Haoguo [ORNL; Pan, Zhengwei [ORNL; Hagaman, Edward {Ed} W [ORNL; Liang, Chengdu [ORNL; Overbury, Steven {Steve} H [ORNL; Dai, Sheng [ORNL

2005-01-01

267

Mechanism of reduction of nitrogen oxides with propene in excess oxygen catalyzed by bifunctional catalysts  

Microsoft Academic Search

HC-SCR (selective reduction of nitrogen oxide by hydrocarbon) and our view on its reaction mechanism are briefly described,\\u000a and then our attempts in the last few years to design catalysts based on the concept of bifunctional catalysis for HC-SCR\\u000a are reviewed. The example chosen is the NO-C3H6-O2-H2O reaction catalyzed by mechanical mixtures of transition metal oxides (e.g., Mn2O3) and metal-loaded

Makoto Misono; Hideaki Niiro; Yoshifumi Hirao

1998-01-01

268

A convenient, novel approach for the synthesis of polyaza macrocyclic bifunctional chelating agents  

Microsoft Academic Search

The convenient, synthetically useful bifunctional chelating agents, (10-p-aminobenzyl)-1,4,7,10-tetraazacyclododecane-1,4,7-triacetate (p-ABz-DO3A) 3 and (11-p-aminobenzyl)-1,4,8,11-tetraazacyclotetradecane-1,4,8-triacetate (p-ABz-TE3A) 6, were obtained by reaction of an ethyl bromoacetate with 1,4,7,10-tetraazacyclododecane and 1,4,8,11-tetraazacyclotetradecane followed by reaction with nitrobenzyl bromide. This method proved more efficient than any described in the literature since the overall yield in a two-step synthesis sequence starting from tetraazamacrocycles was 68%.

Anil Kumar Mishra; Karine Draillard; Alain Faivre-Chauvet; Jean François Gestin; Chantal Curtet; Jean-François Chatal

1996-01-01

269

Hydroinertia gas bearings for micro spinners  

NASA Astrophysics Data System (ADS)

Externally pressurized gas bearings with large bearing clearance are successfully used in ultra-high-speed micro spinners. For example, a micro spinner 4 mm in diameter is stably operated at more than 20 krps and its whirl ratio exceeds 20. In such bearings, the inertia effect of the gas flow in bearing clearance becomes predominant and its Mach number exceeds 1. As a result, gas pressure in the bearing clearance becomes negative. These bearings are called hydroinertia gas bearings, in contrast to the conventional hydrostatic gas bearings. Static characteristics of hydroinertia gas bearings are analyzed by considering the viscous effect of gas as wall friction, and the optimum design of hydroinertia gas bearings is shown. Experimental results on micro spinners and trial design of hydroinertia gas bearings for micro gas turbines are also discussed.

Hikichi, Kousuke; Goto, Satoshi; Togo, Shinichi; Tanaka, Shuji; Isomura, Kousuke

2005-09-01

270

Intrinsic kinetics of one-step dimethyl ether synthesis from hydrogen-rich synthesis gas over bi-functional catalyst  

Microsoft Academic Search

The reaction kinetics of the dimethyl ether synthesis from hydrogen-rich synthesis gas over bi-functional catalyst was investigated\\u000a using an isothermal integral reactor at 220–260°C temperature, 3–7 MPa pressure, and 1,000–2,500 mL\\/g·h space velocity. The\\u000a H2\\/CO ratio of the synthetic gas was chosen between 3 : 1 and 6 : 1. The bi-functional catalyst was prepared by physically mixing\\u000a commercial CuO\\/ZnO\\/Al2O3

Chengyuan Cheng; Haitao Zhang; Weiyong Ying; Dingye Fang

2011-01-01

271

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

272

BEARS: radioactive ion beams at LBNL  

SciTech Connect

BEARS is an initiative to develop a radioactive ion-beam capability at Lawrence Berkeley National Laboratory. The aim is to produce isotopes at an existing medical cyclotron and to accelerate them at the 88'' Cyclotron. To overcome the 300-meter physical separation of these two accelerators, a carrier-gas transport system will be used. At the terminus of the capillary, the carrier gas will be separated and the isotopes will be injected into the 88'' Cyclotron's Electron Cyclotron Resonance (ECR) ion source. The first radioactive beams to be developed will include 20-min {sup 11}C and 70-sec {sup 14}O, produced by (p,n) and (p, {alpha}) reactions on low-Z targets. A test program is currently being conducted at the 88'' Cyclotron to develop the parts of the BEARS system. Preliminary results of these tests lead to projections of initial {sup 11}C beams of up to 2.5x10{sup 7} ions/sec and {sup 14}O beams of 3x10{sup 5} ions/sec.

Powell, J.; Guo, F. Q.; Joosten, R.; Larimer, R.-M.; Lyneis, C.; Moltz, D. M.; Norman, E. B.; O'Neil, J. P.; Rowe, M. W.; VanBrocklin, H. F.; Xie, Z. Q.; Xu, X. J.; Cerny, Joseph [Lawrence Berkeley National Laboratory, University of California, Berkeley, California 94720 (United States); Haustein, P. E. [Chemistry Department, Brookhaven National Laboratory, Upton, New York 11973 (United States)

1998-12-21

273

BEARS: Radioactive ion beams at LBNL  

SciTech Connect

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

Powell, J.; Guo, F.Q. [Lawrence Berkeley National Lab., CA (United States); Haustein, P.E. [Brookhaven National Lab., Upton, NY (United States). Chemistry Dept.] [and others

1998-07-01

274

BEARS: radioactive ion beams at LBNL  

SciTech Connect

BEARS is an initiative to develop a radioactive ion-beam capability at Lawrence Berkeley National Laboratory. The aim is to produce isotopes at an existing medical cyclotron and to accelerate them at the 88{sup {double_prime}} Cyclotron. To overcome the 300-meter physical separation of these two accelerators, a carrier-gas transport system will be used. At the terminus of the capillary, the carrier gas will be separated and the isotopes will be injected into the 88{sup {double_prime}} Cyclotron{close_quote}s Electron Cyclotron Resonance (ECR) ion source. The first radioactive beams to be developed will include 20-min {sup 11}C and 70-sec {sup 14}O, produced by (p,n) and (p, {alpha}) reactions on low-Z targets. A test program is currently being conducted at the 88{sup {double_prime}} Cyclotron to develop the parts of the BEARS system. Preliminary results of these tests lead to projections of initial {sup 11}C beams of up to 2.5{times}10{sup 7}ions/sec and {sup 14}O beams of 3{times}10{sup 5}ions/sec. {copyright} {ital 1998 American Institute of Physics.}

Powell, J.; Guo, F.Q.; Joosten, R.; Larimer, R.-M.; Lyneis, C.; Moltz, D.M.; Norman, E.B.; O`Neil, J.P.; Rowe, M.W.; VanBrocklin, H.F.; Xie, Z.Q.; Xu, X.J.; Cerny, Joseph [Lawrence Berkeley National Laboratory, University of California, Berkeley, California 94720 (United States)] Haustein, P.E. [Chemistry Department, Brookhaven National Laboratory, Upton, New York 11973 (United States)

1998-12-01

275

Understanding the benefits of long travel constant contact side bearings  

Microsoft Academic Search

In 2001, a comprehensive test program was conducted under the AAR strategic research initiatives program by the Transportation Technology Center, Inc. (TTCI), Pueblo, Colorado, to determine the best types of constant contact side bearings (CCSBs) for use in 10 different North American freight cars. Test results indicated that long travel (LT) CCSB designs generally provided the best overall performance, which

D. Iler

2006-01-01

276

STABILITY OF EXTERNALLY PRESSURIZED GAS JOURNAL BEARINGS. Interim Report  

Microsoft Academic Search

A stability analysis is developed for gas journal bearings having ; externally pressurized pads, symmetrically spaced along the circumference. ; Simplifying assumptions are made and equations of flow and motion are stated in ; terms of perturbation quantities. The case considered is when the journal, ; initially in an eccentric equilibrium position, begins to move in an arbitrary ; direction

Licht

1959-01-01

277

Chaotic motions of a rigid rotor in short journal bearings  

Microsoft Academic Search

In the present paper the conditions that give rise to chaotic motions in a rigid rotor on short journal bearings are investigated and determined. A suitable symmetry was given to the rotor, to the supporting system, to the acting system of forces and to the system of initial conditions, in order to restrict the motions of the rotor to translatory

G. Adiletta; A. R. Guido; C. Rossi

1996-01-01

278

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

279

Black Bear Population Dynamics at Cold Lake, Alberta, 1968-70  

Microsoft Academic Search

SUMMARY A black bear (Ursus americanus) population study was initiated near Cold Lake, Alberta in 1968. In the three succeeding years, 108 individual bears have been captured 210 times. Mean estimates of population on the 80 square mile study area have been 78 in 1968,79 in 1969, and 78 in 1970. Sex ratios of trapped subadults and in adults in

G. A. KEMP

280

Evaluation of K(HYNIC)(2) as a bifunctional chelator for (99m)Tc-labeling of small biomolecules.  

PubMed

This study sought to evaluate K(HYNIC)(2) (K = lysine and HYNIC = 6-hydrazinonicotinyl) as a bifunctional chelator for (99m)Tc-labeling of biomolecule. In this study, four K(HYNIC)(2)-conjugated cyclic RGD peptides, K(HYNIC)(2)-RGD(2) (RGD(2) = E[c(RGDfK)](2)), K(HYNIC)(2)-3G-RGD(2) (3G-RGD(2) = Gly-Gly-Gly-E[Gly-Gly-Gly-c(RGDfK)](2)), K(HYNIC)(2)-2P-RGD(2) (2P-RGD(2) = E[PEG4-c(RGDfK)](2), and PEG(4) = 15-amino-4,7,10,13-tetraoxapentadecanoic acid), and K(HYNIC)(2)-3P-RGD(2) (3P-RGD(2) = PEG4-E[PEG4-c(RGDfK)]2) were prepared, and evaluated for their integrin ?v?3 binding affinity. IC(50) values were determined to be 47 ± 2, 35 ± 2, 37 ± 2, 85 ± 2, and 422 ± 15 nM for K(HYNIC)(2)-2P-RGD(2), K(HYNIC)(2)-3P-RGD(2), K(HYNIC)(2)-3G-RGD(2), K(HYNIC)(2)-RGD(2), and c(RGDyK), respectively, against (125)I-echistatin bound to U87MG cells. Macrocyclic complexes [(99m)Tc(K(HYNIC)(2)-RGD(2))(tricine)] (1), [(99m)Tc(K(HYNIC)(2)-3G-RGD(2))(tricine)] (2), [(99m)Tc(K(HYNIC)(2)-2P-RGD(2))(tricine)] (3), and [(99m)Tc(K(HYNIC)(2)-3P-RGD(2))(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 [(99m)Tc(HYNIC)(tricine)(TPPTS)] (TPPTS = trisodium triphenylphosphine-3,3',3"-trisulfonate) with [(99m)Tc(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 (99m)Tc-labeling of small biomolecules with one or more disulfide linkages. PMID:23521129

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

2013-04-08

281

EXPERIMENTAL MEASUREMENT OF PRECISION BEARING DYNAMIC STIFFNESS  

Microsoft Academic Search

Static stiffness measurement of precision bearing components by influence coefficients is complicated by the task of loading and measuring the baseline test fixture stiffness before including the bearing components. Furthermore, as the displacement of the bearing system is measured for various load conditions, the stiffness of high quality bearings may be difficult to distinguish from the test fixture stiffness. The

E. R. Marsh; D. S. Yantek

1997-01-01

282

Magnetic Bearing Sets for a Flywheel System  

Microsoft Academic Search

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

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

2007-01-01

283

Hydroinertia gas bearings for micro spinners  

Microsoft Academic Search

Externally pressurized gas bearings with large bearing clearance are successfully used in ultra-high-speed micro spinners. For example, a micro spinner 4 mm in diameter is stably operated at more than 20 krps and its whirl ratio exceeds 20. In such bearings, the inertia effect of the gas flow in bearing clearance becomes predominant and its Mach number exceeds 1. As

Kousuke Hikichi; Satoshi Goto; Shinichi Togo; Shuji Tanaka; Kousuke Isomura

2005-01-01

284

Contact Sensors on Ceramic Ball Bearings  

Microsoft Academic Search

Integration of micro contact sensors onto a ball bearing is a critical technology necessary for on-line bearing health monitoring in an industrial harsh environment and evaluation of the bearing performance and design. The current planner fabrication methods offered by the MEMS technology restrict the possibility of integrating micro sensor onto a double contoured bearing surface in a more traditional manufacturing

Jia Yi; Frederick Just-Agosto; Edwar Romero

2002-01-01

285

Current Status of Hybrid Bearing Damage Detection  

Microsoft Academic Search

Advances in material development and processing have led to the introduction of ceramic hybrid bearings for many applications. The introduction of silicon nitride hybrid bearings into the high-pressure oxidizer turbopump on the space shuttle main engine led NASA to solve a highly persistent and troublesome bearing problem. Hybrid bearings consist of ceramic balls and steel races. The majority of hybrid

PAULA J. DEMPSEY; JOSEPH M. CERTO; WILFREDO MORALES

2005-01-01

286

A bifunctional enzyme that has both monoacylglycerol acyltransferase and acyl hydrolase activities.  

PubMed

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 HX(4)D 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

2012-08-22

287

Oxidation of phenolic compounds by the bifunctional catalase-phenol oxidase (CATPO) from Scytalidium thermophilum.  

PubMed

The thermophilic fungus Scytalidium thermophilum produces a novel bifunctional catalase with an additional phenol oxidase activity (CATPO); however, its phenol oxidation spectrum is not known. Here, 14 phenolic compounds were selected as substrates, among which (+)-catechin, catechol, caffeic acid, and chlorogenic acid yielded distinct oxidation products examined by reversed-phase HPLC chromatography method. Characterization of the products by LC-ESI/MS and UV-vis spectroscopy suggests the formation of dimers of dehydrocatechin type B (hydrophilic) and type A (hydrophobic), as well as oligomers, namely, a trimer and tetramer from (+)-catechin, the formation of a dimer and oligomer of catechol, a dimer from caffeic acid with a caffeicin-like structure, as well as trimeric and tetrameric derivatives, and a single major product from chlorogenic acid suggested to be a dimer. Based on the results, CATPO oxidizes phenolic compounds ranging from simple phenols to polyphenols but all having an ortho-diphenolic structure in common. The enzyme also appears to have stereoselectivity due to the oxidation of (+)-catechin, but not that of epicatechin. It is suggested that CATPO may contribute to the antioxidant mechanism of the fungus and may be of value for future food and biotechnology applications where such a bifunctional activity would be desirable. PMID:22370948

Koclar Avci, Gulden; Coruh, Nursen; Bolukbasi, Ufuk; Ogel, Zumrut B

2012-02-28

288

Synthesis, conjugation, and radiolabeling of a novel bifunctional chelating agent for (225)Ac radioimmunotherapy applications.  

PubMed

225Ac (t(1/2) = 10 days) is an alternative alpha-emitter that has been proposed for radioimmunotherapy (RIT) due to its many favorable properties, such as half-life and mode of decay. The factor limiting use of (225)Ac in RIT is the lack of an acceptably stable chelate for in vivo applications. Herein is described the first reported bifunctional chelate for (225)Ac that has been evaluated for stability for in vivo applications. The detailed synthesis of a bifunctional chelating agent 2-(4-isothiocyanatobenzyl)-1,4,7,10,13, 16-hexaazacyclohexadecane- 1,4,7,10,13,16-hexaacetic acid (HEHA-NCS) is reported. This ligand was conjugated to three monoclonal antibodies, CC49, T101, and BL-3 with chelate-to-protein ratios between 1.4 and 2. The three conjugates were radiolabeled with (225)Ac, and serum stability study of the [(225)Ac]BL-3-HEHA conjugate was performed. PMID:10898572

Chappell, L L; Deal, K A; Dadachova, E; Brechbiel, M W

289

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

290

Novel Bifunctional Inhibitor of Xylanase and Aspartic Protease: Implications for Inhibition of Fungal Growth  

PubMed Central

A novel bifunctional inhibitor (ATBI) from an extremophilic Bacillus sp. exhibiting an activity against phytopathogenic fungi, including Alternaria, Aspergillus, Curvularia, Colletotricum, Fusarium, and Phomopsis species, and the saprophytic fungus Trichoderma sp. has been investigated. The 50% inhibitory concentrations of ATBI ranged from 0.30 to 5.9 ?g/ml, whereas the MIC varied from 0.60 to 3.5 ?g/ml for the fungal growth inhibition. The negative charge and the absence of periodic secondary structure in ATBI suggested an alternative mechanism for fungal growth inhibition. Rescue of fungal growth inhibition by the hydrolytic products of xylanase and aspartic protease indicated the involvement of these enzymes in cellular growth. The chemical modification of Asp or Glu or Lys residues of ATBI by 2,4,6-trinitrobenzenesulfonic acid and Woodward's reagent K, respectively, abolished its antifungal activity. In addition, ATBI also inhibited xylanase and aspartic protease competitively, with Ki values 1.75 and 3.25 ?M, respectively. Our discovery led us to envisage a paradigm shift in the concept of fungal growth inhibition for the role of antixylanolytic activity. Here we report for the first time a novel class of antifungal peptide, exhibiting bifunctional inhibitory activity.

Dash, Chandravanu; Ahmad, Absar; Nath, Devyani; Rao, Mala

2001-01-01

291

Bifunctional resin-ZVI composites for effective removal of arsenite through simultaneous adsorption and oxidation.  

PubMed

Bifunctional resin-supported nanosized zero-valent iron (N-S-ZVI) composite was developed by combining the oxidation properties of nZVI/O2 with adsorption features of iron oxides and anion-exchange resin N-S. In batch culture experiments, N-S and the N-S-ZVI composite were examined for As(III) and As(V). The results reveal that ZVI in the composite played a key role in enhancing As(III) removal. The N-S-ZVI composites could oxidize more toxic As(III) to less toxic As(V) with high efficiency under ambient conditions without the need of noble metals. At the same time, the oxidized As(V) could be effectively removed by adsorption onto the surface of composites. The mechanisms for the oxidation of As(III) to As(V) and the simultaneous removal of As(V) are proposed. In order to investigate the potential performance of N-S-ZVI in practical use, the effects of solution pH and coexisting anions on arsenite removal and on fixed-bed column treatment of simulated waters were studied. All the results indicated that the bifunctional composites have a great potential for As(III) removal from contaminated waters. PMID:23969401

Du, Qiong; Zhang, Shujuan; Pan, Bingcai; Lv, Lu; Zhang, Weiming; Zhang, Quanxing

2013-08-08

292

Isolation of the bifunctional enzyme lysine 2-oxoglutarate reductase-saccharopine dehydrogenase from Phaseolus vulgaris.  

PubMed

Lysine is catabolyzed by the bifunctional enzyme lysine 2-oxoglutarate reductase-saccharopine dehydrogenase (LOR-SDH) in both animals and plants. LOR condenses lysine and 2-oxoglutarate into saccharopine, using NADPH as cofactor and SDH converts saccharopine into alpha-aminoadipate delta-semialdehyde and glutamic acid, using NAD as cofactor. The distribution pattern of LOR and SDH among different tissues of Phaseolus vulgaris was determined. The hypocotyl contained the highest specific activity, whereas in seeds the activities of LOR and SDH were below the limit of detection. Precipitation of hypocotyl proteins with increasing concentrations of PEG 8000 revealed one broad peak of SDH activity, indicating that two isoforms may be present, a bifunctional LOR-SDH and possibly a monofunctional SDH. During the purification of the hypocotyl enzyme, the LOR activity proved to be very unstable, following ion-exchange chromatography. Depending on the purification procedure, the protein eluted as a monomer of 91-94 kDa containing only SDH activity, or as a dimer of 190 kDa with both, LOR and SDH activities, eluting together. PMID:12624751

Cunha Lima, S T; Azevedo, R A; Santoro, L G; Gaziola, S A; Lea, P J

2003-01-01

293

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

PubMed

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

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

1998-05-01

294

Differentiating the orientations of photosynthetic reaction centers on Au electrodes linked by different bifunctional reagents.  

PubMed

The photosynthetic reaction center (RC) composite film was fabricated by self-assembled monolayers (SAMs) on the Au electrode with two different bifunctional reagents, 4-aminothiophenol (ATP) and 2-mercaptoethylamine (MEA), respectively. The square wave voltametry (SWV), bulk electrolysis and photocurrent test were employed for characterizing the composite film. The dramatic different electrochemical characteristics were observed for the two types of films, which strongly suggested an orientational difference for RC arising from the structural difference between the two bifunctional reagents. For RC-MEA film, three redox peaks which implying electron transfer (ET) between the primary donor (P) and the bacteriopheophytin (Bphe) were observed. While for RC-ATP film, two redox peaks implying ET between the nonheme iron and the primary quinone (Q(A)) were observed. The ET behavior driven by electric field also supported the result that the RC could be linked to the electrode at different sites. The site-specific immobilization approach reported here supplies a method to differentiate the protein orientation. PMID:12052357

Zhao, Jiequan; Zou, Yonglong; Liu, Baohong; Xu, Chunhe; Kong, Jilie

2002-08-01

295

Locally activity-released bifunctional fusion protein enhances antithrombosis and alleviates bleeding risk.  

PubMed

Despite the fact that lytic therapy of thromboembolic disorder has been achieved, reocclusion of the damaged vessels and bleeding complication frequently reduce the therapeutic effect. In order to prevent the vessel reocclusion and enhance the therapeutic effect, combining the anticoagulant with the thrombolytic was assumed. Herein, we propose that restraining but locally releasing anticoagulant activity in the vicinity of thrombus is a way to alleviate the bleeding risk. A bifunctional fusion protein, termed as SFH (Staphylokinase (SAK) linked by FXa recognition peptide at N-terminus of Hirudin (HV)), was designed. SFH retained thrombolytic activity but no anticoagulant activity in thrombus-free blood due to the extension of the N-terminus of HV. However, it could locally liberate intact HV and exhibit anticoagulant activity when FXa or fresh thrombus was present. At equimolar dose, both improved antithrombotic and thrombolytic effects of SFH were observed in kappa-carrageenin inducing mouse-tail thrombosis model and rat inferior vena cava thrombosis model, respectively. Moreover, we observed significantly lower bleeding risk in mice and rats treated with SFH than with the mixture of SAK and HV with monitoring TT (P < 0.01), aPTT (P < 0.05) and PT (P < 0.05), and bleeding time (P < 0.05). In conclusion, SFH is a promising bifunctional therapeutic candidate with lower bleeding risk. PMID:17487572

Shi, Bingxing; Yu, Aiping; Liu, Yuying; Li, Jingchuan; Jin, Jide; Dong, Chunna; Wu, Chutse

2007-05-09

296

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

PubMed Central

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

Maini, Philip K.; Armitage, Judith P.

2010-01-01

297

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

298

IDENTIFICATION OF SPEED-DEPENDENT BEARING PARAMETERS  

Microsoft Academic Search

Bearing dynamic characteristics have been a major unknown in the modelling and analysis of large turbo-generators. An identification algorithm for bearing dynamic characterization by using unbalance response measurements is developed for multi-degree-of-freedom (m.d.o.f.) flexible rotor-bearing systems. The algorithm identifies the bearing dynamic parameters, consisting of four effective stiffness and four damping coefficients for each bearing, utilizing frequency domain synchronous unbalance

R. TIWARI; A. W. LEES; M. I. FRISWELL

2002-01-01

299

A heterogeneous layered bifunctional catalyst for the integration of aerobic oxidation and asymmetric C-C bond formation.  

PubMed

The design and synthesis of a heterogeneous bifunctional chiral catalyst for the sequential aerobic oxidation-asymmetric Michael reactions between primary allylic alcohols and dibenzyl malonate are described. Interestingly, we found that layering bimetallic nanoparticles over the organocatalyst, within the chiral composite material, is crucial for catalytic activity. PMID:24036576

Miyamura, Hiroyuki; Choo, Gerald C Y; Yasukawa, Tomohiro; Yoo, Woo-Jin; Kobayashi, Shu

2013-10-01

300

The bifunctional dihydrofolate reductase thymidylate synthase of Tetrahymena thermophila provides a tool for molecular and biotechnology applications  

Microsoft Academic Search

BACKGROUND: Dihydrofolate reductase (DHFR) and thymidylate synthase (TS) are crucial enzymes in DNA synthesis. In alveolata both enzymes are expressed as one bifunctional enzyme. RESULTS: Loss of this essential enzyme activities after successful allelic assortment of knock out alleles yields an auxotrophic marker in ciliates. Here the cloning, characterisation and functional analysis of Tetrahymena thermophila's DHFR-TS is presented. A first

Lutz Herrmann; Ulrike Bockau; Arno Tiedtke; Marcus WW Hartmann; Thomas Weide

2006-01-01

301

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

Microsoft Academic Search

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

Ho-Young Jung; Branko N. Popov

2009-01-01

302

Influence of the bearing number on micro gas bearing system  

Microsoft Academic Search

This paper employs a numerical method combining the differential transformation method and the finite difference method to study the bifurcation behavior of a rigid rotor supported by a micro gas bearing system. The numerical results reveal a complex dynamic behavior comprising periodic, sub-harmonic, and quasi-periodic responses of the rotor center. Furthermore, the results reveal the changes which take place in

Cheng-Chi Wang; Her-Terng Yau; Yen-Liang Yeh; Ming-Jyi Jang; Jing-Fung Lin

2009-01-01

303

Effects of Bearing Cleaning and Lube Environment on Bearing Performance.  

National Technical Information Service (NTIS)

Running torque data of SR6 ball bearings are presented for different temperatures and speeds. The data are discussed in contrast to generally used torque prediction models and point out the need to obtain empirical data in critical applications. Also, the...

P. C. Ward

1995-01-01

304

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

305

Structural and transcriptional analysis of plant genes encoding the bifunctional lysine ketoglutarate reductase saccharopine dehydrogenase enzyme  

PubMed Central

Background Among the dietary essential amino acids, the most severely limiting in the cereals is lysine. Since cereals make up half of the human diet, lysine limitation has quality/nutritional consequences. The breakdown of lysine is controlled mainly by the catabolic bifunctional enzyme lysine ketoglutarate reductase - saccharopine dehydrogenase (LKR/SDH). The LKR/SDH gene has been reported to produce transcripts for the bifunctional enzyme and separate monofunctional transcripts. In addition to lysine metabolism, this gene has been implicated in a number of metabolic and developmental pathways, which along with its production of multiple transcript types and complex exon/intron structure suggest an important node in plant metabolism. Understanding more about the LKR/SDH gene is thus interesting both from applied standpoint and for basic plant metabolism. Results The current report describes a wheat genomic fragment containing an LKR/SDH gene and adjacent genes. The wheat LKR/SDH genomic segment was found to originate from the A-genome of wheat, and EST analysis indicates all three LKR/SDH genes in hexaploid wheat are transcriptionally active. A comparison of a set of plant LKR/SDH genes suggests regions of greater sequence conservation likely related to critical enzymatic functions and metabolic controls. Although most plants contain only a single LKR/SDH gene per genome, poplar contains at least two functional bifunctional genes in addition to a monofunctional LKR gene. Analysis of ESTs finds evidence for monofunctional LKR transcripts in switchgrass, and monofunctional SDH transcripts in wheat, Brachypodium, and poplar. Conclusions The analysis of a wheat LKR/SDH gene and comparative structural and functional analyses among available plant genes provides new information on this important gene. Both the structure of the LKR/SDH gene and the immediately adjacent genes show lineage-specific differences between monocots and dicots, and findings suggest variation in activity of LKR/SDH genes among plants. Although most plant genomes seem to contain a single conserved LKR/SDH gene per genome, poplar possesses multiple contiguous genes. A preponderance of SDH transcripts suggests the LKR region may be more rate-limiting. Only switchgrass has EST evidence for LKR monofunctional transcripts. Evidence for monofunctional SDH transcripts shows a novel intron in wheat, Brachypodium, and poplar.

2010-01-01

306

Reductive dissolution of arsenic-bearing ferrihydrite  

NASA Astrophysics Data System (ADS)

Ferrihydrites were prepared by coprecipitation (COP) or adsorption (ADS) of arsenate, and the products were characterized using solid-state methods. In addition, the kinetics of reductive dissolution by hydroquinone of these well-characterized materials were quantified. Characterization and magnetism results indicate that the 10 wt% As COP ferrihydrite is less crystalline and possibly has smaller crystallite size than the other ferrihydrites, which all have similar crystallinity and particle size. The results from reductive dissolution experiments show similar reaction rates, reaction mechanism, and activation energy for ferrihydrite precipitated with or without added arsenate. However, a marked decrease in reactivity was observed for 10 wt% As ADS ferrihydrite. The decrease is not attributed to differences in activation energy but rather the preferential blocking of active sites on the ferrihydrite surface. Results demonstrate that arsenic may be released by the reductive dissolution of arsenic-bearing ferrihydrite regardless of whether the arsenic is coprecipitated with or adsorbed onto the ferrihydrite. However, under these reaction conditions, release from materials with adsorbed arsenate greatly exceeds that from materials with coprecipitated arsenate. In fact, a considerable amount of arsenic was released from the 10 wt% ADS ferrihydrite before reductive dissolution was initiated. Therefore, the characterization of arsenate-bearing iron oxide materials to determine the method of arsenate incorporation into structures—perhaps by quantification of Fe-Fe coordination with EXAFS spectroscopy—may lead to improved predictions of the large-scale release of arsenic within aquifer systems under reducing conditions.

Erbs, Jasmine J.; Berquó, Thelma S.; Reinsch, Brian C.; Lowry, Gregory V.; Banerjee, Subir K.; Penn, R. Lee

2010-06-01

307

Bradycardia of the Polar Bear.  

National Technical Information Service (NTIS)

For several years two male polar bears have been studied by long-life implanted physiological radio capsules at the Naval Arctic Research Laboratory, at Point Barrow. A regular measurement has been the resting heart rate; for this we used the lowest heart...

G. E. Folk J. J. Berberich D. K. Sanders

1973-01-01

308

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

309

THE STABILITY OF GAS BEARINGS  

Microsoft Academic Search

In gas bearings involving divergent flow, a rise in pressure along the ; channel due to the Bernouilli effect is superimposed on the pressure drop due to ; viscosity. Under certain conditions this leads to an unstable gas film. A ; preliminary investigation into this effect was made and is presented. (W.L.H.);

1950-01-01

310

Losses of Superconductor Journal Bearing  

NASA Astrophysics Data System (ADS)

A high-temperature superconductor (HTS) journal bearing was studied for rotational loss. Two HTS bearings support the rotor at top and bottom. The rotor weight is 4 kg and the length is about 300 mm. Both the top and bottom bearings have two permanent magnet (PM) rings with an iron pole piece separating them. Each HTS journal bearing is composed of six pieces of superconductor blocks of size 35×25×10 mm. The HTS blocks are encased in a cryochamber through which liquid nitrogen flows. The inner spool of the cryochamber is made from G-10 to reduce eddy current loss, and the rest of the cryochamber is stainless steel. The magnetic field from the PM rings is < 10 mT on the stainless part. The rotational drag was measured over the same speed range at several chamber pressures. Results indicate that a chamber pressure of 0.4 mtorr is sufficiently low to minimize windage loss, and the 10 mT design criterion for the magnetic field on the stainless part of the cryochamber is too high.

Han, Y. H.; Hull, J. R.; Han, S. C.; Jeong, N. H.; Oh, J. M.; Sung, T. H.

2004-06-01

311

Plain Facts About Plain Bearings.  

National Technical Information Service (NTIS)

This citation summarizes a one-page announcement of technology available for utilization. A special report has been prepared as a concise, practical, easy-to-read guide for anyone with an interest in or need for plain bearings. It begins with a brief hist...

1982-01-01

312

Fuzzy Control of Magnetic Bearings.  

National Technical Information Service (NTIS)

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 controll...

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

1991-01-01

313

Superconductor bearings, flywheels and transportation  

Microsoft Academic Search

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

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

2012-01-01

314

Beth Starts Like Brown Bear!  

ERIC Educational Resources Information Center

|Recounts a reading teacher's illuminating experience with a first grader who enjoyed reading Bill Martin's "Brown Bear" books, despite being labeled as dyslexic. Dyslexia is an elusive condition that is biological in origin and distinct from other reading problems. New research shows that reading difficulties, including dyslexia, occur as part of…

Fawcett, Gay

1994-01-01

315

TOOL ASSEMBLY WITH BI-DIRECTIONAL BEARING  

DOEpatents

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

Longhurst, G.E.

1961-07-11

316

Observation of a polar bear with rabies.  

PubMed

On 1 November 1989 the first confirmed case of rabies in a polar bear (Ursus maritimus) was encountered by Inuit hunters in the vicinity of Cape Kendall, Southampton Island, Northwest Territories (Canada). The adult male polar bear had posterior paralysis. Rabies was detected by mouse inoculation and a positive immunoperoxidase reaction on spinal cord and Gasserian ganglion from the bear. Histologic lesions in the lumbar region of the spinal cord were consistent with the posterior paralysis. The impact of rabies on the population dynamics of polar bears probably is minimal. Rabies in polar bears constitutes a potential health hazard for polar bear hunters. PMID:2067058

Taylor, M; Elkin, B; Maier, N; Bradley, M

1991-04-01

317

Long-Term Bearing Wear Tests of Conventional Journal Bearings and Development of Hydrostatic Bearings for the LOFT Drag-Disc Turbine Transducer.  

National Technical Information Service (NTIS)

The details of a two-year development program concerning materials for use as turbine bearings in a pressurized water reactor environment are reported. Two types of bearings have been examined, both conventional journal bearings and hydrostatic bearings. ...

J. R. Fincke

1979-01-01

318

Bifunctional catalyst promotes highly enantioselective bromolactonizations to generate stereogenic C-Br bonds.  

PubMed

A novel bifunctional catalyst derived from BINOL has been developed that promotes the highly enantioselective bromolactonizations of a number of structurally distinct unsaturated acids. Like some known catalysts, this catalyst promotes highly enantioselective bromolactonizations of 4- and 5-aryl-4-pentenoic acids, but it also catalyzes the highly enantioselective bromolactonizations of 5-alkyl-4(Z)-pentenoic acids. These reactions represent the first catalytic bromolactonizations of alkyl-substituted olefinic acids that proceed via 5-exo mode cyclizations to give lactones in which new carbon-bromine bonds are formed at a stereogenic center with high enantioselectivity. We also disclose the first catalytic desymmetrization of a prochiral dienoic acid by enantioselective bromolactonization. PMID:22726214

Paull, Daniel H; Fang, Chao; Donald, James R; Pansick, Andrew D; Martin, Stephen F

2012-06-27

319

Conversion of cellulose to HMF in ionic liquid catalyzed by bifunctional ionic liquids.  

PubMed

A new kind of bifunctional ionic liquid catalysts was synthesized to degrade microcrystalline cellulose in [BMIM]Cl at atmospheric pressure. The effects of reaction temperature, amount of catalysts, reaction time, ionic liquid purity and cellulose concentration on conversion were investigated. At low temperature cellulose can be degraded with being heated in [BMIM]Cl by oil bath. Among the as-synthesized catalysts, Cr([PSMIM]HSO4)3 exhibited the best performance. The HMF yield of 53% and TRS yield of 94% can be achieved at 120 °C in [BMIM]Cl for 5 h over 0.05 g Cr([PSMIM]HSO4)3/2.0 g [BMIM]Cl with 95% cellulose conversion. PMID:23266845

Zhou, Lilong; Liang, Runjuan; Ma, Zhanwei; Wu, Tinghua; Wu, Ying

2012-11-10

320

A Surprising Mechanistic "Switch" in Lewis Acid Activation: A Bifunctional, Asymmetric Approach to ?-Hydroxy Acid Derivatives  

PubMed Central

We report a detailed synthetic and mechanistic study of an unusual bifunctional, sequential hetero-Diels–Alder/ring-opening reaction in which chiral, metal complexed ketene enolates react with o-quinones to afford highly enantioenriched, ?-hydroxylated carbonyl derivatives in excellent yield. A number of Lewis acids were screened in tandem with cinchona alkaloid derivatives; surprisingly, trans-(Ph3P)2PdCl2 was found to afford the most dramatic increase in yield and rate of reaction. A series of Lewis acid binding motifs were explored through molecular modeling, as well as IR, UV and NMR spectroscopy. Our observations document a fundamental mechanistic “switch” – namely the formation of a tandem Lewis base/Lewis acid activated metal enolate in preference to a metal-coordinated quinone species (as observed in other reactions of o-quinone derivatives). This new method was applied to the syntheses of several pharmaceutical targets, each of which was obtained in high yield and enantioselectivity.

Abraham, Ciby J.; Paull, Daniel H.; Bekele, Tefsit; Scerba, Michael T.; Dudding, Travis; Lectka, Thomas

2009-01-01

321

Recent Development of Bifunctional Small Molecules to Study Metal-Amyloid-? Species in Alzheimer's Disease  

PubMed Central

Alzheimer's disease (AD) is a multifactorial neurodegenerative disease related to the deposition of aggregated amyloid-? (A?) peptides in the brain. It has been proposed that metal ion dyshomeostasis and miscompartmentalization contribute to AD progression, especially as metal ions (e.g., Cu(II) and Zn(II)) found in A? plaques of the diseased brain can bind to A? and be linked to aggregation and neurotoxicity. The role of metal ions in AD pathogenesis, however, is uncertain. To accelerate understanding in this area and contribute to therapeutic development, recent efforts to devise suitable chemical reagents that can target metal ions associated with A? have been made using rational structure-based design that combines two functions (metal chelation and A? interaction) in the same molecule. This paper presents bifunctional compounds developed by two different design strategies (linkage or incorporation) and discusses progress in their applications as chemical tools and/or potential therapeutics.

Braymer, Joseph J.; DeToma, Alaina S.; Choi, Jung-Suk; Ko, Kristin S.; Lim, Mi Hee

2011-01-01

322

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.

Mehtala, Maija L.; Lensink, Marc F.; Pietikainen, Laura P.; Hiltunen, J. Kalervo; Glumoff, Tuomo

2013-01-01

323

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

NASA Astrophysics Data System (ADS)

The reaction of a bifunctional ligand, 3-(1-oxo-1,3-dihydro-isoindol-2-yl)-propionic acid (Hpda) with Cu(NO3)2?3H2O in methanol-water in the presence of NaOH at room temperature produces a novel dinuclear copper(II) coordination polymer [Cu2(pda)4]n. The complex is fully characterized in the solid state as well as in solution using various analytical techniques including single crystal X-ray diffraction study. The single crystal X-ray structure analysis reveals that the monomeric unit of complex consists of Cu2(O2CR)4 paddlewheel building unit, where the two copper centers acquire a distorted square pyramidal geometry with amide oxygen of the isoindol ring of an adjacent Hpda ligand sitting on the axial positions.

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

2013-09-01

324

A bifunctional allosteric site in the dimer interface of procaspase-3  

PubMed Central

The dimer interface of caspase-3 contains a bifunctional allosteric site in which the enzyme can be activated or inactivated, depending on the context of the protein. In the mature caspase-3, the binding of allosteric inhibitors to the interface results in an order-to-disorder transition in the active site loops. In procaspase-3, by contrast, the binding of allosteric activators to the interface results in a disorder-to-order transition in the active site. We have utilized the allosteric site to identify a small molecule activator of procaspase and to characterize it's binding to the protease. The data suggest that an efficient activator must stabilize the active conformer of the zymogen by expelling the intersubunit linker from the interface, and it must interact with active site residues found in the allosteric site. Small molecule activators that fulfill the two requirements should provide scaffolds for drug candidates as a therapeutic strategy for directly promoting procaspase-3 activation in cancer cells.

Schipper, Joshua L.; MacKenzie, Sarah H.; Sharma, Anil; Clark, A. Clay

2011-01-01

325

Bifunctional transition metal zeolite catalysts for synthesis gas to gasoline conversion  

SciTech Connect

Conventional Shultz-Flory catalysts suffer from the inherent nonselective product distributions of Shultz-Floryian kinetics. Development of the Mobil M technology is the firest major breakthrough in synthetic fuel technology in 5 decades. To utilize the Mobil m technology, synthesis gas produced from the gasification of coal must first be converted to methanol. The high pressures and/or high recycle ratios necessary, because of the thermodynamics of the methanol synthesis reaction, make the overall cost of this approach prohibitive in today's economy. The logical extension of the Mobil M technology is to use bifunctional Pentasil based catalysts to provide a single reactor route from the synthesis gas to high octane gasoline. Various methods exist to incorporate the CO reduction function with the Pentasil zeolite. The direct synthesis approach, largely overlooked by investigators to date, is emphasized in this research.

Dodwell, G.W.

1984-01-01

326

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

PubMed

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

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

2013-01-07

327

Convenient Synthesis and Evaluation of Heptadentate Bifunctional Ligand for Radioimmunotherapy Applications  

PubMed Central

An efficient synthetic route to a bifunctional chelating agent C-NE3TA-NCS for antibody-targeted radioimmunotherapy (RIT) applications was developed. Various synthetic methods centered on the key reaction steps including bimolecular cyclization, ring opening reactions of aziridine and aziridinium cations, and reductive aminiation were explored to optimize the preparation of a tetraaza-based chelate TANPA and C-NE3TA analogues. Heptadentate C-NE3TA-NCS was conjugated to a tumor targeting antibody and compared to hexadentate C-NOTA-NCS for radiolabeling reaction kinetics with lanthanides for RIT. C-NE3TA-antibody conjugate displayed significantly enhanced complexation kinetics with 90Y as compared to C-NOTA-antibody conjugate. The synthetic methods for TANPA and C-NE3TA-NCS reported herein have broad applications for preparation of bifunctioanl macrocyclic chelating agents.

Chong, Hyun-Soon; Sun, Xiang; Dong, Pengfei; Kang, Chi Soo

2013-01-01

328

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

NASA Astrophysics Data System (ADS)

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.

Atabaev, Timur Sh; Kim, Hyung-Kook; Hwang, Yoon-Hwae

2013-08-01

329

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

330

A novel luminescent bifunctional POSS as a molecular platform for biomedical applications.  

PubMed

A novel luminescent polyhedral oligomeric silsesquioxane (POSS) containing in the structure a fluorescein derivative molecule and a carboxylic functionality, suitable to anchor different organic compounds (dyes, markers, drugs, contrast agents, …), was successfully synthesized and characterized in this manuscript by a multidisciplinary approach. An emission enhancement of the dye of ca. four times was found after reaction with POSS, rendering this new hybrid compound a promising contrast agent for optical imaging. In vitro tests on tumoral HeLa cells demonstrated that the luminescent POSS (namely POSS_F), here described, is able to be taken up in the cell cytosol by an efficient and selective process. Its high chemical versatility and peculiar properties could render this novel bifunctional POSS a molecular platform for biomedical applications. PMID:22576682

Olivero, Francesco; Renò, Filippo; Carniato, Fabio; Rizzi, Manuela; Cannas, Mario; Marchese, Leonardo

2012-05-11

331

Preparation and Characterization of Silica-Coated Magnetic-Fluorescent Bifunctional Microspheres  

PubMed Central

Bifunctional magnetic–fluorescent composite nanoparticles (MPQDs) with Fe3O4MPs and Mn:ZnS/ZnS core–shell quantum dots (QDs) encapsulated in silica spheres were synthesized through reverse microemulsion method and characterized by X-ray powder diffraction, scanning electron microscopy, transmission electron microscopy, vibration sample magnetometer, and photoluminescence (PL) spectra. Our strategy could offer the following features: (1) the formation of Mn:ZnS/ZnS core/shell QDs resulted in enhancement of the PL intensity with respect to that of bare Mn:ZnS nanocrystals due to the effective elimination of the surface defects; (2) the magnetic nanoparticles were coated with silica, in order to reduce any detrimental effects on the QD PL by the magnetic cores; and (3) both Fe3O4MPs and Mn:ZnS/ZnS core–shell QDs were encapsulated in silica spheres, and the obtained MPQDs became water soluble. The experimental conditions for the silica coating on the surface of Fe3O4nanoparticles, such as the ratio of water to surfactant (R), the amount of ammonia, and the amount of tetraethoxysilane, on the photoluminescence properties of MPQDs were studied. It was found that the silica coating on the surface of Fe3O4could effectively suppress the interaction between the Fe3O4and the QDs under the most optimal parameters, and the emission intensity of MPQDs showed a maximum. The bifunctional MPQDs prepared under the most optimal parameters have a typical diameter of 35 nm and a saturation magnetization of 4.35 emu/g at room temperature and exhibit strong photoluminescence intensity.

2009-01-01

332

Construction and Evaluation of a Novel Bifunctional N-Carbamylase-d-Hydantoinase Fusion Enzyme  

PubMed Central

A fully enzymatic process employing two sequential enzymes, d-hydantoinase and N-carbamylase, is a typical case requiring combined enzyme activity for the production of d-amino acids. To test the possibility of generating a bifunctional fusion enzyme, we constructed a fusion protein via end-to-end fusion of a whole gene that encodes an intact protein at the N terminus of the d-hydantoinase. Firstly, maltose-binding protein (MBP) gene of E. coli was fused with d-hydantoinase gene from Bacillus stearothermophilus SD1, and the properties of the resulting fusion protein (MBP-HYD) were compared with those of native d-hydantoinase. Gel filtration and kinetic analyses clearly demonstrated that the typical characteristics of d-hydantoinase are maintained even in a fusion state. Based on this result, we constructed an artificial fusion enzyme composed of the whole length of N-carbamylase (304 amino acids [aa]) from Agrobacterim radiobacter NRRL B11291 and d-hydantoinase (471 aa). The fusion enzyme (CAB-HYD) was functionally expressed with an expected molecular mass of 86 kDa and efficiently converted exogenous hydantoin derivatives to the d-amino acids. A related d-hydantoinase (HYD1) gene from Bacillus thermocatenulatus GH2 was also fused with the N-carbamylase gene at its N terminus. The resulting enzyme (CAB-HYD1) was bifunctional as expected and showed better performance than the CAB-HYD fusion enzyme. The conversion of hydantoin derivatives to corresponding amino acids by the fusion enzymes was much higher than that by the separately expressed enzymes, and comparable to that by the coexpressed enzymes. Thus, the fusion enzyme might be useful as a potential biocatalyst for the production of nonnatural amino acids.

Kim, Geun-Joong; Lee, Dong-Eun; Kim, Hak-Sung

2000-01-01

333

Purification and characterization of a bifunctional alginate lyase from Pseudoalteromonas sp. SM0524.  

PubMed

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 K(m) 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

2011-01-21

334

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

335

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

336

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.

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

2011-01-01

337

Lubrication for high load duplex bearings.  

National Technical Information Service (NTIS)

Three ES and H-compatible lubricants (Environment, Safety and Health) for high load duplex bearing applications were evaluated and compared against trichlorotrifluoroethane (Freon) deposition of low molecular weight polytetrafluoroethylene (PTFE) bearing ...

R. G. Steinhoff

1997-01-01

338

Railcar Roller Bearing Failure Progression Tests.  

National Technical Information Service (NTIS)

This report describes the laboratory endurance test of six railcar roller bearings that had previously suffered physical damage or were otherwise degraded as a result of actual railroad service. Two different onboard impending bearing failure sensors were...

W. D. Waldron

1982-01-01

339

Development of ASTM Precision Bearing Grease Guide.  

National Technical Information Service (NTIS)

Lubricating grease is one of important operational parameter in the rolling bearing applications. Specially, the selection of the lubricating grease for the precision bearing applications is very risky due to many other factors unique to any specific prec...

I. Rhee

2007-01-01

340

Physiological Determinants of Load Bearing Capacity.  

National Technical Information Service (NTIS)

This study identifies some of the physiological determinants of load bearing capacity. Although it is reasonable to assume that maximal aerobic capacity (VO2) is an important determinant of load bearing ability, research implicating the importance of musc...

J. E. Dziados A. I. Damokosh R. P. Mello J. A. Vogel K. L. Farmer

1987-01-01

341

Antarctic Geoscience Initiative  

NASA Astrophysics Data System (ADS)

Antarctia has recently been described as a continent surrounded by advice. The advice stems from growing realization of the Antarctic's importance in many aspects of globalscale Earth science. This article outlines a U.S. and international initiative to move solid-Earth scientists from an advisory role to one of acquiring new data bearing on the structure and evolution of the ice-covered Antarctic lithosphere.The initiative has marine, airborne, and terrestrial components; plans for all three are underway. Platforms exist for undertaking the work at sea and in the air, but land geophysical techniques need to be adapted to the Antarctic environment. An international workshop to plan modern over-ice geoscience transects will be convened in Washington, D.C., July 19-22 in conjunction with the 28th International Geological Congress (IGC).

Dalziel, Ian W. D.; Zimmerman, Herman B.

342

Identification of bifunctional 12\\/3 fatty acid desaturases for improving the ratio of 3 to 6 fatty acids in microbes and plants  

Microsoft Academic Search

We report the identification of bifunctional 12\\/3 desaturases from Fusarium moniliforme, Fusarium graminearum, and Magnaporthe grisea. The bifunctional activity of these desaturases distinguishes them from all known 12 or 3 fatty acid desaturases. The 3 desaturase activity of these enzymes also shows a broad 6 fatty acid substrate specificity by their ability to convert linoleic acid (LA), -linolenic acid, di-homo--linolenic

Howard G. Damude; Hongxiang Zhang; Leonard Farrall; Kevin G. Ripp; Jean-Francois Tomb; Dieter Hollerbach; Narendra S. Yadav

2006-01-01

343

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

344

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

345

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

346

Bears and Pipeline Construction in Alaska  

Microsoft Academic Search

Serious problems were encountered with bears during construction of the 1274-km-long trans-Alaska oil pipelinebetween Prudhoe Bay and Valdez. This multi-billion-dollar project traversed both black bear (Ursus americanus Pallas) and grizzly bear (U. arctos L.) habitat throughout its entire length. Plans for dealing with anticipated problems with bears were often inadequate. Most (71 %) problems occurred north of the Yukon River

ERICH H. FOLLMANN; JOHN L. HECHTEL

347

Performance of a hybrid cylindrical roller bearing  

Microsoft Academic Search

A 206-size hybrid (ceramic\\/steel) cylindrical roller bearing was tested in MIL-L-23699 C oil at several speeds and loads. Heat-generation data was collected and subsequently correlated with bearing-analysis software. Bearing-cage slip data was also collected at various oil-flow rates, oil temperatures, and with both MIL-L-7808 J and MIL-L-23699 C oils. The hybrid bearing was tested in MIL-L-23699 C oil for for

Stephen M. Schrader

1992-01-01

348

Design Handbook on Gas Bearings for Gyroscopes.  

National Technical Information Service (NTIS)

This report presents the work accomplished thus far in the preparation of a design handbook on gas bearings for the spin-axis of gyroscopes. The ultimate handbook will contain design data on four different bearings: (1) the spiral-grooved thrust bearing; ...

J. H. Vohr C. Y. Chow

1966-01-01

349

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

350

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

351

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

352

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

353

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

354

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

355

49 CFR 229.69 - Side bearings.  

Code of Federal Regulations, 2011 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...

2011-10-01

356

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

357

Teaching American History with Teddy's Bear.  

ERIC Educational Resources Information Center

Discusses the origins of "Teddy's bear," tracing back to a cartoon published in 1902. States that Teddy's bear can shed light on U.S. culture and society. Focuses on the role of Teddy's bear as a symbol of conservationism, an embodiment of male dominance and female nurturance, and a manifestation of white racial supremacy. (CMK)

Forman-Brunell, Miriam

2001-01-01

358

A Spherical Gas Bearing for Airborne Application  

Microsoft Academic Search

A spherical gas bearing is analyzed and tested for an airborne application. The externally pressurized bearing supports an inertially stabilized 36-in aperture, infrared telescope. The bearing provides the isolation of rotary motion from the aircraft and also serves as a seal between the aircraft cabin and cavity condition at 50, 000 ft altitude. The accompanying temperature gradient of 135 F

Anton Bouvier; John C. Schmertz

1975-01-01

359

Stability of high stiffness gas journal bearings  

Microsoft Academic Search

One of the most important problems in the design of gas bearings is their stability. In this paper, results of investigations of the stability of a new type of gas journal bearing, the so-called 'high stiffness bearing' (HSB), are presented. As linear models of HSB do not allow us to estimate the stability threshold with satisfactory precision, all the numerical

Krzysztof Czolczynski

1994-01-01

360

Vibration in Grease Lubricated Bearing Systems  

Microsoft Academic Search

In this study a dynamic bearing apparatus is designed, developed and used to evaluate noise and vibration of bearings lubricated with various greases under different operating conditions. Eight different greases are evaluated for their vibration and noise characteristics. The threshold, kurtosis and mean square methods are used to quantify grease vibration and rank the greases based on their bearing vibration.

Sundar Ramamurthy; Charles M. Krousgrill; Farshid Sadeghi

2000-01-01

361

Superconducting magnetic bearings for energy storage flywheels  

Microsoft Academic Search

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

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

1999-01-01

362

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

363

Teaching American History with Teddy's Bear.  

ERIC Educational Resources Information Center

|Discusses the origins of "Teddy's bear," tracing back to a cartoon published in 1902. States that Teddy's bear can shed light on U.S. culture and society. Focuses on the role of Teddy's bear as a symbol of conservationism, an embodiment of male dominance and female nurturance, and a manifestation of white racial supremacy. (CMK)|

Forman-Brunell, Miriam

2001-01-01

364

Cryptosporidiosis in a black bear in Virginia.  

PubMed

Cryptosporidiosis has not been previously reported in black bears in North America, either free-roaming or captive. However, oocysts have been documented in two captive Malayan sun bears (Helarctos malayanus) located in zoological parks in Taiwan. Developmental stages of Cryptosporidium parvum were observed in tissue sections from the small intestine of a black bear cub found dead in Virginia (USA). PMID:10231767

Duncan, R B; Caudell, D; Lindsay, D S; Moll, H D

1999-04-01

365

Gas Bearing Implementation of Small Cryocooler Compressor  

Microsoft Academic Search

In order to reduce the life-cycle cost of systems that use cryocoolers, it is necessary to extend the operating life of the cooler beyond what is currently available for tactical military applications. Several approaches have been used to increase life such as flexure bearing and gas bearing support. It was determined that a gas bearing system offered a novel and

D. T. Kuo; A. S. Loc; M. Hanes

2006-01-01

366

Grease Life Prediction for Sealed Ball Bearings  

Microsoft Academic Search

Sealed ball bearings are used widely for electric motors and automotive components. Appropriate grease is selected for the each application, considering grease life, bearing torque, sound characteristics, etc. Recently, as these components have become progressively more compact, the sealed ball bearings are required to operate at higher temperatures and rotational speeds. In such cases, grease life has become more critical

T. Kawamura; M. Minami; M. Hirata

2001-01-01

367

36 CFR 13.1236 - Bear orientation.  

Code of Federal Regulations, 2010 CFR

...2009-07-01 2009-07-01 false Bear orientation. 13.1236 Section 13...Brooks Camp Developed Area § 13.1236 Bear orientation. All persons visiting the BCDA must receive an NPS-approved Bear Orientation. Failure to receive an...

2009-07-01

368

36 CFR 13.1236 - Bear orientation.  

Code of Federal Regulations, 2010 CFR

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

2010-07-01

369

36 CFR 13.1236 - Bear orientation.  

Code of Federal Regulations, 2013 CFR

...2013-07-01 2013-07-01 false Bear orientation. 13.1236 Section 13...Brooks Camp Developed Area § 13.1236 Bear orientation. All persons visiting the BCDA must receive an NPS-approved Bear Orientation. Failure to receive an...

2013-07-01

370

FIELD TESTS OF POTENTIAL POLAR BEAR REPELLENTS  

Microsoft Academic Search

Field tests of potential repellents were made on free-ranging polar bears (Ursus maritimus) near Churchill, Manitoba, from 11 October through 12 November 1978. Polar bears were attracted to an observation\\/testing area with sardine baits at 11 sites. Commercial dog repellents and household chemicals were tested for their ability to keep bears from visiting baited sites, recorded sounds were tested for

GARY D. MILLER

371

Minimizing electric bearing currents in ASD systems  

Microsoft Academic Search

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

P. J. Link

1999-01-01

372

The BEAR Beamline at Elettra  

SciTech Connect

The BEAR (Bending Magnet for Emission Absorption and Reflectivity) beamline is installed at the right exit of the 8.1 bending magnet at ELETTRA. The beamline - in operation since January 2003 - delivers linear and circularly polarized radiation in the 5 - 1600 eV energy range. The experimental station is composed of a UHV chamber for reflectivity, absorption, fluorescence and angle resolved photoemission measurements and a UHV chamber for in-situ sample preparation.

Nannarone, S.; Pasquali, L.; Selvaggi, G. [UdR-INFM Modena, Universita di Modena and Reggio Emilia, Via Vignolese 905, 41100 Modena (Italy); Borgatti, F.; DeLuisa, A.; Doyle, B.P.; Gazzadi, G.C.; Giglia, A.; Finetti, P.; Pedio, M. [TASC-INFM, MM building in Area Science Park, s.s.14 km 163.5, 34012 Basovizza, Trieste (Italy); Mahne, N. [TASC-INFM, Universita di Trieste, Trieste (Italy); Naletto, G.; Pelizzo, M.G.; Tondello, G. [LUXOR-INFM, Universita di Padova, Padua (Italy)

2004-05-12

373

Fracture of mobile unicompartmental knee bearings: A parametric finite element study.  

PubMed

Cases of fractured mobile unicompartmental knee bearings have recently been reported. The purpose of this study was to understand the mechanics behind these fractures and to examine the influence of different design modifications. A parametric finite element model was used to examine the influence of different geometrical factors on the stresses within the bearing. Crack initiation occurred clinically in the centre of the bearing; this correlated with the position of the maximum von Mises stress. Tensile stresses, thought to propagate the fatigue crack, were maximal at the medial-lateral sides of the bearing, and the tensile vectors were normal to the fracture direction observed clinically. Fully congruent femoral articulation on the bearing, use of a thicker bearing size, and minimising wear of the component reduced the risk of fracture. For example, an unworn 6.5-mm-thick bearing (no clinical fractures reported) had 21.6% lower medial-lateral tensile stress compared to an unworn 3.5 mm bearing (five clinical fractures reported). In turn, an unworn 3.5 mm bearing had 34.3% lower tensile stress compared to a 3.5 mm bearing after 1.9 mm wear (average linear wear reported for clinically fractured bearings). The fracture risk was also reduced when the radio-opaque marker wire was positioned further from the centre of the bearing, and when marker balls were used instead of marker wires (19% reduction in tensile stress in some regions). These results indicate the importance of minimising component wear; the data also support the current component design which uses posterior marker balls instead of marker wires, and the continuing use of a congruous femoral component. PMID:23940210

Pegg, Elise C; Murray, David W; Pandit, Hemant G; O'Connor, John J; Gill, Harinderjit S

2013-08-12

374

Stability analysis of a disk-spindle supported by a plain journal bearing and pivot bearing  

Microsoft Academic Search

A hydrodynamic bearing is widely used for hard disk drives, and it is better than a ball bearing in terms of vibration suppression, noise reduction and shock resistance. However, its cost to performance ratio should be further improved. In this study we analyzed the stability of a disk-spindle assembly supported by a hydrodynamic plain journal bearing and a pivot bearing

Kyosuke Ono; Seiji Murashita; Hiroshi Yamaura

2005-01-01

375

On the Control of Synchronous Vibration in Rotor\\/Magnetic Bearing Systems Involving Auxiliary Bearing Contact  

Microsoft Academic Search

During the normal operation of rotor\\/magnetic bearing systems, contacts with auxiliary bearings or bushes are avoided. However, auxiliary bearings are required under abnor- mal conditions and in malfunction situations to prevent contact between the rotor and stator laminations. Studies in the open literature deal largely with rotor drop and the requirements of auxiliary bearings design parameters for safe rundown. Rotor

P. S. Keogh; M. O. T. Cole; M. N. Sahinkaya; C. R. Burrows

2004-01-01

376

ON THE DESIGN OF AN ACTIVE AUXILIARY BEARING FOR ROTOR\\/MAGNETIC BEARING SYSTEMS  

Microsoft Academic Search

This paper considers the design of an actively con- trolled auxiliary bearing system for use with mag- netic bearings. During rotor\\/auxiliary bearing con- tact large frictional contact forces can lead to signif- icant thermal stresses. Furthermore, the non-linear nature of the contact can induce unfavourable rotor dynamic behaviour. An active auxiliary bearing ca- pable of reducing the contact forces and

Iain S. Cade; M. Necip Sahinkaya; Cliord R. Burrows; Patrick S. Keogh

377

ADAPTIVE CONTROL OF ACTIVE MAGNETIC BEARINGS TO PREVENT ROTOR-BEARING CONTACT  

Microsoft Academic Search

Active Magnetic Bearing (AMB) systems offer various ad- vantages over conventional bearings but due to their limited force capacity, with high levels of vibrations the rotor may come into contact with retainer bearings. Under conventional PID control, when a rotor comes into contact with its retainer bear- ings it remains in contact, until the rotor is run down and the

Abdul-Hadi G. Abulrub; M. Necip Sahinkaya; Clifford R. Burrows; Patrick S. Keogh

378

Catalytic asymmetric aza-Morita-Baylis-Hillman reaction of methyl acrylate: role of a bifunctional La(O-iPr)3/linked-BINOL complex.  

PubMed

The catalytic asymmetric aza-Morita-Baylis-Hillman reaction using unactivated methyl acrylate is described. A simple Lewis acidic metal catalyst, such as La(OTf)(3), was not suitable for the reaction, but rare earth metal alkoxide/linked-BINOL complexes possessing bifunctional Lewis acid and Brønsted base properties efficiently promoted the reaction in combination with an achiral nucleophilic organocatalyst. The combined use of a La(O-iPr)(3)/(S,S)-TMS-linked-BINOL complex with a catalytic amount of DABCO promoted the aza-Morita-Baylis-Hillman reaction of a broad range of N-diphenylphosphinoyl imines. Products from aryl, heteroaryl, and alkenyl imines were obtained in 67-99% yield and 81-95% ee. It is noteworthy that isomerizable alkyl imines could be employed as well, giving products in 78-89% yield and 94-98% ee. Initial rate kinetic studies as well as kinetic isotope effect experiments using alpha-deuterio-methyl acrylate support the importance of both the nucleophilicity of La-enolate and the Brønsted basicity of a La-catalyst for promoting the reaction. PMID:20690698

Yukawa, Takafumi; Seelig, Bianca; Xu, Yingjie; Morimoto, Hiroyuki; Matsunaga, Shigeki; Berkessel, Albrecht; Shibasaki, Masakatsu

2010-09-01

379

Identification of the pgmG Gene, Encoding a Bifunctional Protein with Phosphoglucomutase and Phosphomannomutase Activities, in the Gellan Gum-Producing Strain Sphingomonas paucimobilis ATCC 31461  

PubMed Central

The pgmG gene of Sphingomonas paucimobilis ATCC 31461, the industrial gellan gum-producing strain, was cloned and sequenced. It encodes a 50,059-Da polypeptide that has phosphoglucomutase (PGM) and phosphomannomutase (PMM) activities and is 37 to 59% identical to other bifunctional proteins with PGM and PMM activities from gram-negative species, including Pseudomonas aeruginosa AlgC. Purified PgmG protein showed a marked preference for glucose-1-phosphate (G1P); the catalytic efficiency was about 50-fold higher for G1P than it was for mannose-1-phosphate (M1P). The estimated apparent Km values for G1P and M1P were high, 0.33 and 1.27 mM, respectively. The pgmG gene allowed the recovery of alginate biosynthetic ability in a P. aeruginosa mutant with a defective algC gene. This result indicates that PgmG protein can convert mannose-6-phosphate into M1P in the initial steps of alginate biosynthesis and, together with other results, suggests that PgmG may convert glucose-6-phosphate into G1P in the gellan pathway.

Videira, Paula A.; Cortes, Luisa L.; Fialho, Arsenio M.; Sa-Correia, Isabel

2000-01-01

380

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

PubMed

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

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

2011-03-30

381

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

PubMed Central

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

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

2011-01-01

382

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

PubMed Central

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

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

2013-01-01

383

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

PubMed

Antibiotic-producing Streptomyces are complex bacteria that remodel global transcription patterns and their nucleoids during development. Here, we describe a novel developmentally regulated nucleoid-associated protein, DdbA, of the genus that consists of an N-terminal DNA-binding histone H1-like domain and a C-terminal DksA-like domain that can potentially modulate RNA polymerase activity in conjunction with ppGpp. Owing to its N-terminal domain, the protein can efficiently bind and condense DNA in vitro. Loss of function of this DNA-binding protein results in changes in both DNA condensation during development and the ability to adjust DNA supercoiling in response to osmotic stress. Initial analysis of the DksA-like activity of DdbA indicates that overexpression of the protein suppresses a conditional deficiency in antibiotic production of relA mutants that are unable to synthesise ppGpp, just as DksA overexpression in Escherichia coli can suppress ppGpp(0) phenotypes. The null mutant is also sensitive to oxidative stress owing to impaired upregulation of transcription of sigR, encoding an alternative sigma factor. Consequently, we propose this bifunctional histone-like protein as a candidate that could structurally couple changes in DNA conformation and transcription during the streptomycete life-cycle and in response to stress. PMID:23525459

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

2013-03-21

384

Polymeric biomaterials for load-bearing medical devices  

Microsoft Academic Search

This paper aims to give a broad overview of the challenges that are faced in load-bearing medical devices and focuses specifically\\u000a on the challenges faced in utilizing polymeric materials in such applications. Three specific cases are given in the field\\u000a of polymeric biomaterials. These cases build in complexity and initiate with examination of the evolution of intravascular\\u000a catheter design in

Lisa Pruitt; Jevan Furmanski

2009-01-01

385

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

2012-03-02

386

A bifunctional endoglucanase/endoxylanase from Cellulomonas flavigena with potential use in industrial processes at different pH.  

PubMed

Cellulomonas flavigena CDBB-531 was found to secrete a bifunctional cellulase/xylanase with a molecular mass of 49 kDa and pI 4.3. This enzyme was active on Remazol brilliant blue-carboxymethylcellulose (RBB-CMC) and Remazol brilliant blue-xylan (RBB-X). Based on thin-layer chromatographic analysis of the degradation products, the cellulase activity produced glucose, cellobiose, cellotriose, and cellotetraose from CMC as the substrate. When xylan from birchwood was used, end products were xylose, arabinose, and xylobiose. The bifunctional enzyme showed a pH optimum of 6 for cellulase activity and 9 for xylanase activity, which pointed out that this enzyme had separate sites for each activity. In both cases, the apparent optimum temperature was 50 degrees C. The predicted amino acid sequence of purified protein showed similarity with the catalytic domain of several glycosyl hydrolases of family 10. PMID:18379842

Pérez-Avalos, Odilia; Sánchez-Herrera, Leticia M; Salgado, Luis M; Ponce-Noyola, Teresa

2008-04-01

387

Valve assembly having remotely replaceable bearings  

DOEpatents

A valve assembly having remotely replaceable bearings is disclosed wherein a valve disc is supported within a flow duct for rotation about a pair of axially aligned bearings, one of which is carried by a spindle received within a diametral bore in the valve disc, and the other of which is carried by a bearing support block releasably mounted on the duct circumferentially of an annular collar on the valve disc coaxial with its diametrical bore. The spindle and bearing support block are adapted for remote removal to facilitate servicing or replacement of the valve disc support bearings.

Johnson, Evan R. (San Diego, CA); Tanner, David E. (Poway, CA)

1980-01-01

388

76 FR 47149 - Initiation of Five-Year (“Sunset”) Review: Correction  

Federal Register 2010, 2011, 2012, 2013

...included two revoked antidumping duty orders, Ball Bearings and Parts Thereof from Japan (A-588-804) (third review) and Ball Bearings and Parts Thereof from the United...initiating Sunset Reviews in August 2011. See Ball Bearings and Parts Thereof From Japan...

2011-08-04

389

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

PubMed

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

2010-09-01

390

Fiber-Optic Probe Based on a Bifunctional Lensed Photonic Crystal Fiber for Refractive Index Measurements of Liquids  

Microsoft Academic Search

We report a fiber-optic sensor for measuring the re- fractive index (RI) of a liquid sample. The sensing probe is con- structed from an extrinsic cavity formed by a micromirror and a lensedphotoniccrystalfiber(PCF)tip.WeshowthatPCFlenswith an unconventionally large radius of curvature is bifunctional ;a n effective reflector as well as a collimator and thus suitable for re- alizing long single-arm interferometers, with

Gopinath Mudhana; Kwan Seob Park; Seon Young Ryu; Byeong Ha Lee

2011-01-01

391

Development of 177Lu-nanobodies for radioimmunotherapy of HER2-positive breast cancer: evaluation of different bifunctional chelators.  

PubMed

Nanobodies show favourable pharmacokinetic characteristics for tumor targeting, including high tumor-to-background-ratios. Labelled with a therapeutic radionuclide, nanobodies could be used as an adjuvant treatment option for HER2-overexpressing minimal residual disease. The therapeutic radionuclide Lutetium-177 is linked to the nanobody using a bifunctional chelator. The choice of the bifunctional chelator could affect the in vivo behaviour of the radiolabeled nanobody. Consequently, we compared four different bifunctional chelators - p-SCN-Bn-DOTA, DOTA-NHS-ester, CHX-A"-DTPA or 1B4M-DTPA - in order to select the optimal chemical link between Lutetium-177 and a HER2 targeting nanobody. MS results revealed different degrees of chelator-conjugation. High stability in time was observed, together with nanomolar affinities on HER2-expressing tumor cells. Ex vivo biodistributions as well as SPECT/micro-CT analyses showed high activities in tumors expressing medium HER2 levels with low background activity except for the kidneys. The 1B4M-DTPA-coupled conjugate was further evaluated in a high HER2-expressing tumor model. Here, tumor uptake values of 5.99?±?0.63, 5.12?±?0.17, 2.83?±?0.36 and 2.47?±?0.38 %IA/g were obtained at 1, 3, 24 and 48h p.i., which coincided with exceptionally low background values, except for the kidneys, and unprecedented tumor-to-background ratios. No specific binding was observed in a HER2-negative model. In conclusion, the in-house developed anti-HER2 nanobody 2Rs15dHIS can be successfully labeled with (177) Lu using different bifunctional chelators. Both macrocyclic and acyclic chelators show high stability in time. High specific tumor uptake combined with the lowest background uptake was measured using the 1B4M-DTPA-based conjugate. PMID:22434639

D'Huyvetter, Matthias; Aerts, An; Xavier, Catarina; Vaneycken, Ilse; Devoogdt, Nick; Gijs, Marlies; Impens, Nathalie; Baatout, Sarah; Ponsard, Bernard; Muyldermans, Serge; Caveliers, Vicky; Lahoutte, Tony

392

Toward building a database of bifunctional probes for the MS3D investigation of nucleic acids structures  

Microsoft Academic Search

This report illustrates the approaches employed to investigate critical aspects of the activity of crosslinking reagents toward\\u000a nucleic acid substrates, which should be evaluated to identify candidate probes for mass spectrometric 3D (MS3D) investigations\\u000a of biomolecules and macromolecular complexes. Representative members of different classes of bifunctional reagents were taken\\u000a into consideration, including bikethoxal and phenyl-diglyoxal [bis-(1,2-dicarbonyls)], cisplatin (coordinative binding agents),

Qingrong Zhang; Eizadora T. Yu; Katherine A. Kellersberger; Elizabeth Crosland; Daniele Fabris

2006-01-01

393

Dissolution of Pre-Existing Platelet Thrombus by Synergistic Administration of Low Concentrations of Bifunctional Antibodies against ?3 Integrin  

Microsoft Academic Search

Most antithrombotic approaches target prevention rather than the more clinically relevant issue of resolution of an existing thrombus. In this study, we describe a novel and effective therapeutic strategy for ex vivo clearance of pre-existing platelet thrombus by the combination of two bifunctional platelet GPIIIa49-66 ligands that target different parts of the arterial thrombus. We produced an additional GPIIIa49-66 agent

Suying Dang; Tao Hong; Thomas Wisniewski; Wei Zhang

2011-01-01

394

Conformational flexibility in the peripheral site of Torpedo californica acetylcholinesterase revealed by the complex structure with a bifunctional inhibitor.  

PubMed

The X-ray crystallographic structure of Torpedo californica acetylcholinesterase (TcAChE) in complex with the bifunctional inhibitor NF595, a potentially new anti-Alzheimer drug, has been solved. For the first time in TcAChE, a major conformational change in the peripheral-site tryptophan residue is observed upon complexation. The observed conformational flexibility highlights the dynamic nature of protein structures and is of importance for structure-based drug design. PMID:16594661

Colletier, Jacques Ph; Sanson, Benoît; Nachon, Florian; Gabellieri, Emanuele; Fattorusso, Caterina; Campiani, Giuseppe; Weik, Martin

2006-04-12

395

Identification and expression studies of a catalase and a bifunctional catalase-peroxidase in Frankia strain R43  

Microsoft Academic Search

A monofunctional catalase and a bifunctional catalase-peroxidase were revealed by activity staining of non-denaturing PAGE in Frankia strain R43. Both enzymes were shown to be cytoplasmatic, growth regulated and expressed mainly during the stationary growth phase. Nevertheless, low levels of constitutive expression could also be detected during the early stages of growth. Immunoblot analyses using a polyclonal antibody raised against

Fernando Tavares; Lisandro Bernardo; Anita Sellstedt

2003-01-01

396

Structure, genomic organization and transcription of the bifunctional dihydrofolate reductase-thymidylate synthase gene from Crithidia fasciculata  

Microsoft Academic Search

The bifunctional dihydrofolate reductase-thymidylate synthase (DHFR-TS) gene from the monogenetic kinetoplastid proto­ zoan, Criihidia fasciculata, was isolated and characterized. The gene is located on a single chromosome of approximately one me- gabase, and shows significant sequence similarity to other eukaryotic and prokaryotic DHFR and TS genes. There is a single low- abundance polyadenylated DHFR-TS transcript of approximately 3100 nt. One

Dallas E. Hughes; Opeolu A. Shonekan; Larry Simpson

1989-01-01

397

Statistical analysis of the performance of a bi-functional catalyst under operating conditions of LPDME process  

Microsoft Academic Search

Liquid phase direct synthesis of dimethyl ether (LPDME™) under various operating conditions (temperature, H2\\/CO molar ratio of feed) was conducted in a mechanically agitated slurry reactor system. Each run was monitored for 60h time on stream (TOS) in order to confirm the high activity and long-term stability of a bi-functional catalytic system (CuO–ZnO–Al2O3\\/H-MFI-90). Statistical experimental design was applied for determining

G. R. Moradi; M. Nazari; F. Yaripour

2008-01-01

398

Structural dynamics of the actomyosin complex probed by a bifunctional spin label that crosslinks SH1 and SH2  

Microsoft Academic Search

We have used a bifunctional spin label (BSL) to cross-link Cys707 (SH1) and Cys697 (SH2) in the catalytic domain of myosin subfragment 1 (S1). BSL induces the same weakened ATPase activity and actin-binding affinity that is observed when SH1 and SH2 are cross-linked with pPDM, which traps an analog of the post-hydrolysis state AMADPP. Electron paramagnetic resonance showed that BSL

Andrew R. Thompson; Nariman Naber; Clyde Wilson; Roger Cooke

399

Chemical fixation of carbon dioxide to cyclic carbonates under extremely mild conditions with highly active bifunctional catalysts  

Microsoft Academic Search

Chemical fixation of carbon dioxide to cyclic carbonates proceeds effectively under extremely mild temperature and pressure by using a bifunctional nucleophile–electrophile catalyst system of tetradentate Schiff-base aluminum complexes ((Salen)AlX) in conjunction with a quaternary ammonium salt (n-Bu4NY) in the absence of any organic solvent. Electrophilicity of central Al3+ ion and the steric factor of substituent groups on the aromatic rings

Xiao-Bing Lu; Ying-Ju Zhang; Bin Liang; Xiao Li; Hui Wang

2004-01-01

400

Recovery of plutonium from nitric acid containing oxalate and fluoride by a macroporous bifunctional phosphinic acid resin (MPBPA)  

Microsoft Academic Search

Summary  The sorption of Pu from nitric acid solutions containing oxalate\\/fluoride was studied using an indigenously available macroporous\\u000a bifunctional phosphinic acid (MPBPA) resin. Batch experiments were carried out to obtain the distribution data of Pu(IV) with\\u000a a view to optimize conditions for its recovery from nitric acid waste solutions containing oxalate or fluoride ions. The measurements\\u000a showed high distribution ratio (D)

K. Venugopal Chetty; A. G. Godbole; R. Swarup; V. N. Vaidya; V. Venugopal; P. R. Vasudeva Rao

2005-01-01

401

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

Microsoft Academic Search

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

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

2010-01-01

402

Gas Bearing Implementation of Small Cryocooler Compressor  

NASA Astrophysics Data System (ADS)

In order to reduce the life-cycle cost of systems that use cryocoolers, it is necessary to extend the operating life of the cooler beyond what is currently available for tactical military applications. Several approaches have been used to increase life such as flexure bearing and gas bearing support. It was determined that a gas bearing system offered a novel and cost effective approach for our products. This paper presents the implementation of a gas bearing system into the miniature cryocooler compressor. The theoretical analyses used to design the gas bearing system will be discussed and empirical data comparing the performance between the baseline and gas bearing coolers will be presented. A life test program is being undertaken to verify the life characteristics of the gas bearing cooler and the results will be summarized and published at a later date.

Kuo, D. T.; Loc, A. S.; Hanes, M.

2006-04-01

403

Lubrication for high load duplex bearings  

SciTech Connect

Three ES and H-compatible lubricants (Environment, Safety and Health) for high load duplex bearing applications were evaluated and compared against 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. Bearings with Supercritical CO{sub 2} deposition of PTFE extracted from Vydax AR/IPA, bearings with titanium carbide coated balls, and bearings with diamond-like carbon races and retainers were evaluated. Bearings with Supercritical CO{sub 2} deposition of PTFE from Vydax AR/IPA performed as well as bearings with Freon deposition of PTFE from Freon-based Vydax.

Steinhoff, R.G.

1997-08-01

404

Identification of potentially new bifunctional RNA based on genome-wide data-mining of alternative splicing events.  

PubMed

It is now evident that the transcriptional output of the genome is much more complex than estimates based on the number of protein-coding genes, and that non-coding RNA widely increase the source of regulatory molecules, a role previously ascribed to proteins. Furthermore, the recent characterization of bifunctional RNA, i.e. RNA for which both coding capacity and activity as functional RNA have been reported, adds an additional degree of complexity. Based on the SRA (Steroid Receptor RNA Activator) model, where bifunctionality is regulated by alternative splicing, we hypothesized that similar cases, not yet formally tested experimentally, might exist. Using freely available data from high-throughput sequencing projects, we propose here a bioinformatical identification of mRNA whose ORF are disrupted by alternative splicing events, especially by intron retention, and potentially representing a cognate non-coding RNA. Our data-mining approach revealed that the human genome contains around 300 possibilities of potentially new bifunctional RNA. PMID:21729736

Ulveling, Damien; Francastel, Claire; Hubé, Florent

2011-06-26

405

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 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, J.R.

1980-05-02

406

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.

2013-01-01

407

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

PubMed

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 muM, 7.8 +/- 1.3 muM and 2.06 +/- 0.4 muM. 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

Jordão, Fabiana M; Gabriel, Heloisa B; Alves, João Mp; Angeli, Claudia B; Bifano, Thaís D; Breda, Ardala; de Azevedo, Mauro F; Basso, Luiz A; Wunderlich, Gerhard; Kimura, Emilia A; Katzin, Alejandro M

2013-06-01

408

Turbocharger bearing retention and lubrication system  

SciTech Connect

This patent describes exhausts gas driven turbocharger. It comprises a housing, a shaft within the housing having a longitudinal axis of rotation and a pair of ends, a compressor wheel mounted within the housing on one end of the shaft for rotation therewith, a turbine wheel mounted within the housing on the other end of the shaft for rotation therewith, means for communicating air to the compressor wheel, means for communicating exhaust gas to the turbine wheel to cause the latter to rotate the shaft and the compressor wheel mounted thereon to compress the air communicated to the compressor wheel, and bearing means mounting the shaft for rotation relative to the housing, the bearing means including a bearing outer ring, a bearing inner ring, and ball bearing elements supporting the bearing outer ring on the bearing inner ring, a bearing locating aperture in the bearing outer ring, and an elongated bearing location pin having a longitudinal axis of symmetry extending transversely to the longitudinal axis of the shaft.

Gutknecht, D.A.

1991-12-31

409

Test of a habitat suitability index for black bears in the southern Appalachians  

USGS Publications Warehouse

We present a habitat suitability index (HSI) model for black bears (Ursus americanus) living in the southern Appalachians that was developed a priori from the literature, then tested using location and home range data collected in the Pisgah Bear Sanctuary, North Carolina, over a 12-year period. The HSI was developed and initially tested using habitat and bear data collected over 2 years in the sanctuary. We increased number of habitat sampling sites, included data collected in areas affected by timber harvest, used more recent Geographic Information System (GIS) technology to create a more accurate depiction of the HSI for the sanctuary, evaluated effects of input variability on HSI values, and duplicated the original tests using more data. We found that the HSI predicted habitat selection by bears on population and individual levels and the distribution of collared bears were positively correlated with HSI values. We found a stronger relationship between habitat selection by bears and a second-generation HSI. We evaluated our model with criteria suggested by Roloff and Kernohan (1999) for evaluating HSI model reliability and concluded that our model was reliable and robust. The model's strength is that it was developed as an a priori hypothesis directly modeling the relationship between critical resources and fitness of bears and tested with independent data. We present the HSI spatially as a continuous fitness surface where potential contribution of habitat to the fitness of a bear is depicted at each point in space.

Mitchell, M. S.; Zimmerman, J. W.; Powell, R. A.

2002-01-01

410

Post-den emergence behavior of polar bears (Ursus maritimus) in Northern Alaska  

USGS Publications Warehouse

We observed polar bear (Ursus maritimus) maternity den sites on Alaska's North Slope in March 2002 and 2003 in an effort to describe bears' post-den emergence behavior. During 40 sessions spanning 459 h, we observed 8 adults and 14 dependent cubs outside dens for 37.5 h (8.2% of total observation time). There was no significant difference between den emergence dates in 2002 (mean = 15 Mar ?? 4.1 d) and 2003 (mean = 21 Mar ?? 2.1 d). Following initial den breakout, polar bears remained at their den sites for 1.5 to 14 days (mean = 8.1 ?? 5.1 d). The average length of stay in dens between emergent periods was significantly shorter in 2002 (1.79 h) than in 2003 (4.82 h). While outside, adult bears were inactive 49.5% of the time, whereas cubs were inactive 13.4% of the time. We found no significant relationships between den emergence activity and weather. Adult polar bears at den sites subjected to industrial activity exhibited significantly fewer bouts of vigilance than denned bears in undisturbed areas (t = -5.5164, df = 4, p = 0.00). However, the duration of vigilance behaviors at sites near industrial activity was not significantly shorter than at the other sites studied (t = -1.8902, df = 4, p = 0.07). Results for these bears were within the range of findings in other studies of denned polar bears. ?? The Arctic Institute of North America.

Smith, T. S.; Partridge, S. T.; Amstrup, S. C.; Schliebe, S.

2007-01-01

411

Mechanics of superconducting magnetic bearings  

SciTech Connect

Levitation forces and lateral forces in relation to the gaps in superconducting bearings were measured using a beam-and-camera system. Dynamic magnetic stiffness derived from vibration tests were compared to static magnetic stiffness. The relaxation of magnetic forces as a function of time was measured as well. The behavior of levitation forces at temperatures from 4.2 K to 77 K were studied. A rotor equipped with two superconducting bearings was fabricated and was spun up to 120,000 RPM. The drag torques acting on the rotor were measured at both atmospheric pressure and at a partial vacuum of a few mm Hg. Many high-temperature superconductors of different compositions fabricated through different processing techniques were investigated by measuring the magnetic force-gap relationships. The data indicated that YBa{sub 2}Cu{sub 3}O{sub 7} specimens made of melt-quench process produced the largest magnetic forces obtained in the laboratory so far. Models predicting the magnetic forces between superconductors and externally applied magnetic fields were studied. A numerical scheme based on the magnetization model was developed. The calculated levitation force-gap relationships showed a reasonable agreement with experimental results.

Chang, Peizen.

1991-01-01

412

Bifunctional rhodamine probes of Myosin regulatory light chain orientation in relaxed skeletal muscle fibers.  

PubMed

The orientation of the regulatory light chain (RLC) region of the myosin heads in relaxed skinned fibers from rabbit psoas muscle was investigated by polarized fluorescence from bifunctional rhodamine (BR) probes cross-linking pairs of cysteine residues introduced into the RLC. Pure 1:1 BR-RLC complexes were exchanged into single muscle fibers in EDTA rigor solution for 30 min at 30 degrees C; approximately 60% of the native RLC was removed and stoichiometrically replaced by BR-RLC, and >85% of the BR-RLC was located in the sarcomeric A-bands. The second- and fourth-rank order parameters of the orientation distributions of BR dipoles linking RLC cysteine pairs 100-108, 100-113, 108-113, and 104-115 were calculated from polarized fluorescence intensities, and used to determine the smoothest RLC orientation distribution-the maximum entropy distribution-consistent with the polarized fluorescence data. Maximum entropy distributions in relaxed muscle were relatively broad. At the peak of the distribution, the "lever" axis, linking Cys707 and Lys843 of the myosin heavy chain, was at 70-80 degrees to the fiber axis, and the "hook" helix (Pro830-Lys843) was almost coplanar with the fiber and lever axes. The temperature and ionic strength of the relaxing solution had small but reproducible effects on the orientation of the RLC region. PMID:15041671

Brack, Andrew S; Brandmeier, Birgit D; Ferguson, Roisean E; Criddle, Susan; Dale, Robert E; Irving, Malcolm

2004-04-01

413

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

PubMed

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

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

2007-08-28

414

The structure of the conserved neurotrophic factors MANF and CDNF explains why they are bifunctional.  

PubMed

We have solved the structures of mammalian mesencephalic astrocyte-derived neurotrophic factor (MANF) and conserved dopamine neurotrophic factor (CDNF). CDNF protects and repairs midbrain dopaminergic neurons in vivo; MANF supports their survival in culture and is also cytoprotective against endoplasmic reticulum (ER) stress. Neither protein structure resembles any known growth factor but the N-terminal domain is a saposin-like lipid-binding domain. MANF and CDNF may thus bind lipids or membranes. Consistent with this, there are two patches of conserved lysines and arginines. The natively unfolded MANF C-terminus contains a CKGC disulphide bridge, such as reductases and disulphide isomerases, consistent with a role in ER stress response. The structure thus explains why MANF and CDNF are bifunctional; neurotrophic activity may reside in the N-terminal domain and ER stress response in the C-terminal domain. Finally, we identified three changes, (MANF)I10-->K(CDNF), (MANF)E79-->M(CDNF) and (MANF)K88-->L(CDNF), that may account for the biological differences between the proteins. PMID:19258449

Parkash, Vimal; Lindholm, Päivi; Peränen, Johan; Kalkkinen, Nisse; Oksanen, Esko; Saarma, Mart; Leppänen, Veli-Matti; Goldman, Adrian

2009-03-03

415

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.

Liu, Shuang

2008-01-01

416

Bifunctional apoptosis inhibitor (BAR) protects neurons from diverse cell death pathways.  

PubMed

The bifunctional apoptosis regulator (BAR) is a multidomain protein that was originally identified as an inhibitor of Bax-induced apoptosis. Immunoblot analysis of normal human tissues demonstrated high BAR expression in the brain, compared to low or absent expression in other organs. Immunohistochemical staining of human adult tissues revealed that the BAR protein is predominantly expressed by neurons in the central nervous system. Immunofluorescence microscopy indicated that BAR localizes mainly to the endoplasmic reticulum (ER) of cells. Overexpression of BAR in CSM 14.1 neuronal cells resulted in significant protection from a broad range of cell death stimuli, including agents that activate apoptotic pathways involving mitochondria, TNF-family death receptors, and ER stress. Downregulation of BAR by antisense oligonucleotides sensitized neuronal cells to induction of apoptosis. Moreover, the search for novel interaction partners of BAR identified several candidate proteins that might contribute to the regulation of neuronal apoptosis (HIP1, Hippi, and Bap31). Taken together, the expression pattern and functional data suggest that the BAR protein is involved in the regulation of neuronal survival. PMID:14502241

Roth, W; Kermer, P; Krajewska, M; Welsh, K; Davis, S; Krajewski, S; Reed, J C

2003-10-01

417

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

2013-04-07

418

Mechanism of tetralin ring opening and contraction over bifunctional Ir/SiO?-Al?O? Catalysts.  

PubMed

The development of cleaner fuels from conventional resources requires the finding of new hydrotreatment processes able to improve the combustion performances of fuels and limit undesirable emissions. In the context of gas oil upgrading by selective ring opening, we have investigated the hydroconversion of tetralin over iridium nanoparticles supported on amorphous silica-alumina. The conversion of tetralin leads to hydrogenation, ring-contraction, and ring-opening products. The selectivity to ring-opening/-contraction products (ROCPs) increases linearly with the acid-metal site ratio and can be tuned by modifying the metal loading, the metal nanoparticle size, or the support composition. From the combination of catalytic tests at variable conversion and the products identification by two-dimensional gas chromatography, a mechanistic reaction scheme has been established. Aromatic ROCPs are formed through purely acidic steps, whereas the formation of saturated ROCPs mostly involves bifunctional reaction steps. Iridium-catalyzed hydrogenolysis appears to be a minor pathway with respect to iridium-catalyzed hydrogenation and Brønsted acid catalyzed isomerization. PMID:22949005

Piccolo, Laurent; Nassreddine, Salim; Toussaint, Guy; Geantet, Christophe

2012-07-02

419

Crystal structure of a DNA containing the planar, phenoxazine-derived bi-functional spectroscopic probe ?  

PubMed Central

Previously, we developed the deoxycytosine analog Ç (C-spin) as a bi-functional spectroscopic probe for the study of nucleic acid structure and dynamics using electron paramagnetic resonance (EPR) and fluorescence spectroscopy. To understand the effect of Ç on nucleic acid structure, we undertook a detailed crystallographic analysis. A 1.7?Å resolution crystal structure of Ç within a decamer duplex A-form DNA confirmed that Ç forms a non-perturbing base pair with deoxyguanosine, as designed. In the context of double-stranded DNA Ç adopted a planar conformation. In contrast, a crystal structure of the free spin-labeled base ç displayed a ?20° bend at the oxazine linkage. Density function theory calculations revealed that the bent and planar conformations are close in energy and exhibit the same frequency for bending. These results indicate a small degree of flexibility around the oxazine linkage, which may be a consequence of the antiaromaticity of a 16-? electron ring system. Within DNA, the amplitude of the bending motion is restricted, presumably due to base-stacking interactions. This structural analysis shows that the Ç forms a planar, structurally non-perturbing base pair with G indicating it can be used with high confidence in EPR- or fluorescence-based structural and dynamics studies.

Edwards, Thomas E.; Cekan, Pavol; Reginsson, Gunnar W.; Shelke, Sandip A.; Ferre-D'Amare, Adrian R.; Schiemann, Olav; Sigurdsson, Snorri Th.

2011-01-01

420

Characterization of a recombinant bifunctional xylosidase/arabinofuranosidase from Phanerochaete chrysosporium.  

PubMed

A bifunctional xylosidase/arabinofuranosidase gene (PcXyl) was cloned from the cDNA library of Phanerochaete chrysosporium and further expressed in Pichia pastoris. Enzymatic assay indicated that P. pastoris produced rPcXyl at a level of 26,141 U l?¹. The xylosidase and arabinofuranosidase activities of rPcXyl were maximized, respectively, at pHs of 5.0 and 5.5 and temperatures of 45°C and 50°C. SDS-PAGE revealed a single band of purified rPcXyl of 83 kDa. Cu²? and Zn²? completely inhibited the enzyme activity of rPcXyl. The enzyme activity of rPcXyl was increased 151%, 126% and 123%, respectively, in the presence of glucose, xylose and arabinose at concentrations of 5 mM. rPcXyl hydrolyzed xylobiose to xylose and xylotriose to xylose and xylobiose, indicating rPcXyl acts as an exo-type enzyme. Additionally, rPcXyl enhanced xylose release from xylan substrates in synergy with rPcXynC. PMID:23474097

Huy, Nguyen Duc; Thayumanavan, Palvannan; Kwon, Tae-Ho; Park, Seung-Moon

2013-03-07

421

Studies on stability of bi-functional P3HT:PCBM:rubrene optoelectronic devices  

NASA Astrophysics Data System (ADS)

Investigations are carried out for stability in photovoltaic response of bifunctional electroluminescent and photovoltaic devices, based on ternary blend of poly(3-hexylthiophene) (P3HT), phenyl [6,6']C61 butyric acid methyl ester (PCBM), and 5,6,11,12-tetraphenylnaphthacene (rubrene). P3HT and PCBM are important and the most frequent materials used for photovoltaic applications, therefore, for relative comparison, photovoltaic cells were also prepared using a binary mixture of P3HT and PCBM. Devices based on the ternary blend exhibited better stability in all photovoltaic parameters and the lifetime was almost doubled, but their photovoltaic efficiency was lower than that of those based on the binary blend. Longer lifetime of ternary blend devices is because of a relatively better thermal, electrochemical, and morphological stabilities of the ternary blend system. However, the lower efficiencies are because of the reduced photo-current and low fill factor ( FF) due to an increased recombination and introduction of defects/trapping sites by rubrene molecules.

Gaur, Ankita; Kumar, Pankaj

2013-06-01

422

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

PubMed Central

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

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

2011-01-01

423

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

424

Molecular characterization of bifunctional hydroxymethyldihydropterin pyrophosphokinase-dihydropteroate synthase from Plasmodium falciparum.  

PubMed

A 2118-base pair gene encoding the bifunctional hydroxymethyldihydropterin pyrophosphokinase-dihydropteroate syntheses of Plasmodium falciparum (pfPPPK-DHPS) was expressed under the control of the T5 promoter in a DHPS-deficient Escherichia coli strain. The enzyme was purified to near homogeneity using nickel affinity chromatography followed by gel filtration and migrates as an intense band on sodium dodecyl sulfate-polyacrylamide gel electrophoresis with apparent mass of approximately 83 kDa. Gel filtration suggested that the native pfPPPK-DHPS might exist as a tetramer of identical subunits. The enzyme was found to be Mg2+ - and ATP-dependent and had optimal temperature ranging from 37 to 45 degrees C with peak activity at pH 10. Sodium chloride and potassium chloride at 0.2 and 0.4 M, respectively, activated the activity of the enzyme but higher salt concentrations were inhibitory. Guanidine-HCl and urea inhibited the enzyme activity by 50% at 0.25 and 0.9 M, respectively. Kinetic properties of the recombinant pfPPPK-DHPS were investigated. Sulfathiazole and dapsone were potent inhibitors of pfPPPK-DHPS, whilst sulfadoxine, sulfanilamide, sulfacetamide and p-aminosalicylic acid were less inhibitory. Our construct provides an abundant source of recombinant pfPPPK-DHPS for crystallization and drug screening. PMID:15279950

Kasekarn, Waraporn; Sirawaraporn, Rachada; Chahomchuen, Thippayarat; Cowman, Alan F; Sirawaraporn, Worachart

2004-09-01

425

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

PubMed

A novel bifunctional catalase with an additional phenol oxidase activity was isolated from a thermophilic fungus, Scytalidium thermophilum. This extracellular enzyme was purified ca. 10-fold with 46% yield and was biochemically characterized. The enzyme contains heme and has a molecular weight of 320 kDa with four 80 kDa subunits and an isoelectric point of 5.0. Catalase and phenol oxidase activities were most stable at pH 7.0. The activation energies of catalase and phenol oxidase activities of the enzyme were found to be 2.7 +/- 0.2 and 10.1 +/- 0.4 kcal/mol, respectively. The pure enzyme can oxidize o-diphenols such as catechol, caffeic acid, and L-DOPA in the absence of hydrogen peroxide and the highest oxidase activity is observed against catechol. No activity is detected against tyrosine and common laccase substrates such as ABTS and syringaldazine with the exception of weak activity with p-hydroquinone. Common catechol oxidase inhibitors, salicylhydroxamic acid and p-coumaric acid, inhibit the oxidase activity. Catechol oxidation activity was also detected in three other catalases tested, from Aspergillus niger, human erythrocyte, and bovine liver, suggesting that this dual catalase-phenol oxidase activity may be a common feature of catalases. PMID:18369615

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

2008-03-28

426

Bifunctional sucrose phosphate synthase/phosphatase is involved in the sucrose biosynthesis by Methylobacillus flagellatus KT.  

PubMed

The aerobic obligate methylotroph Methylobacillus flagellatus KT was shown to synthesize sucrose in the presence of 0.5-2% NaCl in the growth medium. In the genome of this bacterium, an open reading frame (ORF) encoding a predicted 84-kD polypeptide homologous to the plant and cyanobacterial sucrose phosphate synthases (SPSs) was found. Using heterologous expression of the putative sps gene in Escherichia coli, followed by affinity chromatography, pure recombinant protein SPS-His6 was obtained. The enzyme catalyzed two reactions: conversion of fructose 6-phosphate and UDP-glucose into sucrose 6-phosphate and hydrolysis of sucrose 6-phosphate to sucrose. The bifunctional sucrose phosphate synthase/phosphatase (SPS/SPP) was a 340 kDa homotetrameric Mg(2+) -dependent enzyme activated by fructose 1,6-phosphate2 and ATP but inhibited by glucose 6-phosphate, fructose 1-phosphate, AMP and inorganic phosphate. The amino acid sequence of the protein had a C-terminal domain homologous to SPPs. This correlated with the absence of the spp gene in the M. flagellatus chromosome. The ORFs homologous to the M. flagellatus SPS were found in the genomes of another obligate methylotroph Methylovorus glucosetrophus as well as the lithoautotrophic bacteria Acidithiobacillus ferrooxidans, Nitrosomonas europaea and Nitrosospira multiformis whose genomes lacked the spp genes. Thus, data extending the knowledge of biochemical properties of bacterial SPSs have been obtained. PMID:23865613

But, Sergey Y; Khmelenina, Valentina N; Reshetnikov, Alexander S; Trotsenko, Yuri A

2013-08-12

427

GGAPs, a New Family of Bifunctional GTP-Binding and GTPase-Activating Proteins  

PubMed Central

G proteins are molecular switches that control a wide variety of physiological functions, including neurotransmission, transcriptional activation, cell migration, cell growth. and proliferation. The ability of GTPases to participate in signaling events is determined by the ratio of GTP-bound to GDP-bound forms in the cell. All known GTPases exist in an inactive (GDP-bound) and an active (GTP-bound) conformation, which are catalyzed by guanine nucleotide exchange factors and GTPase-activating proteins (GAPs), respectively. In this study, we identified and characterized a new family of bifunctional GTP-binding and GTPase-activating proteins, named GGAP. GGAPs contain an N-terminal Ras homology domain, called the G domain, followed by a pleckstrin homology (PH) domain, a C-terminal GAP domain, and a tandem ankyrin (ANK) repeat domain. Expression analysis indicates that this new family of proteins has distinct cell localization, tissue distribution, and even message sizes. GTPase assays demonstrate that GGAPs have high GTPase activity through direct intramolecular interaction of the N-terminal G domain and the C-terminal GAP domain. In the absence of the GAP domain, the N-terminal G domain has very low activity, suggesting a new model of GGAP protein regulation via intramolecular interaction like the multidomain protein kinases. Overexpression of GGAPs leads to changes in cell morphology and activation of gene transcription.

Xia, Chunzhi; Ma, Wenbin; Stafford, Lewis Joe; Liu, Chengyu; Gong, Liming; Martin, James F.; Liu, Mingyao

2003-01-01

428

Employing bifunctional enzymes for enhanced extraction of bioactives from plants: flavonoids as an example.  

PubMed

A cost-effective and environmentally friendly approach was developed to improve the extraction of active ingredients from plants, in which a bifunctional enzyme was employed for not only facilitating cell wall degradation but also increasing the bioactivity of target compounds in the extract. In the aqueous extraction of flavonoids from Glycyrrhizae radix , Trichoderma viride cellulase, a commercial cell-wall-degrading enzyme, was found to efficiently deglycosylate liquiritin and isoliquiritin, which are of high content but low bioactivity, into their aglycones that have much higher physiological activities for dietary and medicinal uses. Under optimized conditions, the extraction yield of liquiritigenin and isoliquiritigenin aglycones reached 4.23 and 0.39 mg/g of dry weight (dw) with 6.51- and 3.55-fold increases, respectively. The same approach was expanded to the extraction of flavonoids from Scutellariae radix using Penicillium decumbens naringinase, where enhanced production of more bioactive bacalein and wogonin was achieved via enzymatic deglycosylation of bacalin and wogonoside. PMID:23869387

Xu, Ming-Shu; Chen, Shuo; Wang, Wen-Quan; Liu, Si-Qin

2013-08-09

429

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

PubMed

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 (CH(3)OH). By placing [(p-cymene)RuCl(2)](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 (HCOOCH(3)). The Ru (IV) intermediate is not observed when the DESI spray solution is sparged with Ar gas, indicating that O(2) 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 HCOOCH(3). These results represent an example that species generated from the (?-amino alcohol)(arene)RuCl (II) catalytic precursor can selectively oxidize CH(3)OH to HCOOCH(3). 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

2012-02-06

430

The Structural Basis for a Coordinated Reaction Catalyzed by a Bifunctional Glycosyltransferase in Chondroitin Biosynthesis*  

PubMed Central

Bifunctional chondroitin synthase K4CP catalyzes glucuronic acid and N-acetylgalactosamine transfer activities and polymerizes a chondroitin chain. Here we have determined that an N-terminal region (residues 58–134) coordinates two transfer reactions and enables K4CP to catalyze polymerization. When residues 58–107 are deleted, K4CP loses polymerase activity while retaining both transfer activities. Peptide 113DWPSDL118 within this N-terminal region interacts with C-terminal peptide 677YTWEKI682. The deletion of either sequence abolishes glucuronic acid but not N-acetylgalactosamine transfer activity in K4CP. Both donor bindings and transfer activities are lost by mutating 677YTWEKI682 to 677DAWEDI682. On the other hand, acceptor substrates retain their binding to K4CP mutants. The characteristics of these K4CP mutants highlight different states of the enzyme reaction, providing an underlying structural basis for how these peptides play essential roles in coordinating the two glycosyltransferase activities for K4CP to elongate the chondroitin chain.

Sobhany, Mack; Kakuta, Yoshimitsu; Sugiura, Nobuo; Kimata, Koji; Negishi, Masahiko

2012-01-01

431

Linalool Dehydratase-Isomerase, a Bifunctional Enzyme in the Anaerobic Degradation of Monoterpenes*  

PubMed Central

Castellaniella (ex Alcaligenes) defragrans strain 65Phen mineralizes monoterpenes in the absence of oxygen. Soluble cell extracts anaerobically catalyzed the isomerization of geraniol to linalool and the dehydration of linalool to myrcene. The linalool dehydratase was present in cells grown on monoterpenes, but not if grown on acetate. We purified the novel enzyme ?1800-fold to complete homogeneity. The native enzyme had a molecular mass of 160 kDa. Denaturing gel electrophoresis revealed one single protein band with a molecular mass of 40 kDa, which indicated a homotetramer as native conformation. The aerobically purified enzyme was anaerobically activated in the presence of 2 mm DTT. The linalool dehydratase catalyzed in vitro two reactions in both directions depending on the thermodynamic driving forces: a water secession from the tertiary alcohol linalool to the corresponding acyclic monoterpene myrcene and an isomerization of the primary allylalcohol geraniol in its stereoisomer linalool. The specific activities (Vmax) were 140 nanokatals mg?1 for the linalool dehydratase and 410 nanokatals mg?1 for the geraniol isomerase, with apparent Km values of 750 ?m and 500 ?m, respectively. The corresponding open reading frame was identified and revealed a precursor protein with a signal peptide for a periplasmatic location. The amino acid sequence did not affiliate with any described enzymes. We suggest naming the enzyme linalool dehydratase-isomerase according to its bifunctionality and placing it as a member of a new protein family within the hydrolyases (EC 4.2.1.X).

Brodkorb, Danny; Gottschall, Matthias; Marmulla, Robert; Luddeke, Frauke; Harder, Jens

2010-01-01

432

Purification and Characterization of the Bifunctional Enzyme Lysine-Ketoglutarate Reductase-Saccharopine Dehydrogenase from Maize.  

PubMed

The first enzyme of the lysine degradation pathway in maize (Zea mays L.), lysine-ketoglutarate reductase, condenses lysine and [alpha]-ketoglutarate into saccharopine using NADPH as a cofactor, whereas the second, saccharopine dehydrogenase, converts saccharopine to [alpha]-aminoadipic-[delta]-semialdehyde and glutamic acid using NAD+ or NADP+ as a cofactor. The reductase and dehydrogenase activities are optimal at pH 7.0 and 9.0, respectively. Both enzyme activities, co-purified on diethylaminoethyl-cellulose and gel filtration columns, were detected on nondenaturing polyacrylamide gels as single bands with identical electrophoretic mobilities and share tissue specificity for the endosperm. The highly purified preparation containing the reductase and dehydrogenase activities showed a single polypeptide band of 125 kD on sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The native form of the enzyme is a dimer of 260 kD. Limited proteolysis with elastase indicated that lysine-ketoglutarate reductase and saccharopine dehydrogenase from maize endosperm are located in two functionally independent domains of a bifunctional polypeptide. PMID:12226216

Goncalves-Butruille, M.; Szajner, P.; Torigoi, E.; Leite, A.; Arruda, P.

1996-03-01

433

Gel electrophoresis of a charge-regulated, bi-functional particle.  

PubMed

Adopting a Brinkman fluid model, we analyzed the electrophoresis of a charged-regulated, bi-functional particle containing both acidic and basic functional groups in a gel solution. Both the long-range hydrodynamic effect arising from the liquid drag and the short-range steric effect from particle-polymer interaction are considered. The type of particle considered is capable of simulating both biocolloids such as microorganisms and cells, and particles with adsorbed polyelectrolyte or membrane layer. Our model describes successfully the experimental data in the literature. The presence of gel has the effect of reducing the particle mobility and alleviating double-layer polarization so that the particle behavior is less complicated than that in the case where gel is absent. On the other hand, both the quantitative and qualitative behaviors of a particle depend highly on solution pH and background salt concentration, yielding interesting and significant results. These results provide valuable information for both experimental data interpretation and electrophoresis devices design. PMID:23161269

Hsu, Jyh-Ping; Huang, Chih-Hua; Tseng, Shiojenn

2013-01-30

434

Bifunctional NMN adenylyltransferase/ADP ribose pyrophosphatase: structure and function in bacterial NAD metabolism  

PubMed Central

Summary Bacterial NadM-Nudix is a bifunctional enzyme containing a nicotinamide mononucleotide (NMN) adenylyltransferase and an ADP-ribose pyrophosphatase domain. While most members of this enzyme family, such as that from a model cyanobacterium Synechocystis sp., are involved primarily in NAD savage/recycling pathways, its close homolog in a category A biodefense pathogen Francisella tularensis likely plays a central role in a recently discovered novel pathway of NAD de novo synthesis. The crystal structures of NadM-Nudix from both species, including their complexes with various ligands and catalytic metal ions, revealed detailed configurations of the substrate binding and catalytic sites in both domains. The structure of the N-terminal NadM domain may be exploited for designing new anti-tularemia therapeutics. The ADP-ribose binding site in the C-terminal Nudix domain is substantially different from that of E. coli ADP-ribose pyrophosphatase, and is more similar to human NUDT9. The latter observation provided new insights into the ligand binding mode of ADPR-gated Ca2+ channel TRPM2.

Huang, Nian; Sorci, Leonardo; Zhang, Xuejun; Brautigan, Chad; Li, Xiaoqing; Raffaelli, Nadia; Magni, Giulio; Grishin, Nick V.; Osterman, Andrei; Zhang, Hong

2008-01-01

435

Purification and Characterization of the Bifunctional Enzyme Lysine-Ketoglutarate Reductase-Saccharopine Dehydrogenase from Maize.  

PubMed Central

The first enzyme of the lysine degradation pathway in maize (Zea mays L.), lysine-ketoglutarate reductase, condenses lysine and [alpha]-ketoglutarate into saccharopine using NADPH as a cofactor, whereas the second, saccharopine dehydrogenase, converts saccharopine to [alpha]-aminoadipic-[delta]-semialdehyde and glutamic acid using NAD+ or NADP+ as a cofactor. The reductase and dehydrogenase activities are optimal at pH 7.0 and 9.0, respectively. Both enzyme activities, co-purified on diethylaminoethyl-cellulose and gel filtration columns, were detected on nondenaturing polyacrylamide gels as single bands with identical electrophoretic mobilities and share tissue specificity for the endosperm. The highly purified preparation containing the reductase and dehydrogenase activities showed a single polypeptide band of 125 kD on sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The native form of the enzyme is a dimer of 260 kD. Limited proteolysis with elastase indicated that lysine-ketoglutarate reductase and saccharopine dehydrogenase from maize endosperm are located in two functionally independent domains of a bifunctional polypeptide.

Goncalves-Butruille, M.; Szajner, P.; Torigoi, E.; Leite, A.; Arruda, P.

1996-01-01

436

Bifunctional molecules evade cytochrome P(450) metabolism by forming protective complexes with FK506-binding protein.  

PubMed

Despite their large size and complexity, the macrolide natural products rapamycin and FK506 have excellent pharmacological characteristics. We hypothesize that these unexpected properties may arise from protective, high affinity interactions with the cellular FK506-binding protein, FKBP. In this model, the drug-FKBP complex might sequester the small molecule and limit its degradation by restricting access to metabolic enzymes. In support of this idea, we found that adding FKBP blocks binding of FK506 to the common cytochrome P(450) enzyme CYP3A4 in vitro. To further test this idea, we have systematically modified a small collection of otherwise unrelated compounds, such that they acquire affinity for FKBP. Strikingly, we found that many of these synthetic derivatives, but not the unmodified parent compounds, are also protected from CYP3A4-mediated metabolism. Depending on the properties of the linker, the bifunctional molecules exhibited up to a 3.5-fold weaker binding to CYP3A4, and this protective effect was observed in the presence of either purified FKBP or FKBP-expressing cells. Together, these results suggest that the surprising pharmacology of rapamycin and FK506 might arise, in part, from binding to their abundant, intracellular target, FKBP. Furthermore, these findings provide a framework by which other small molecules might be systematically modified to impart this protective effect. PMID:18493655

Marinec, Paul S; Lancia, Jody K; Gestwicki, Jason E

2008-04-18

437

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

2013-09-20

438

Evolution of the Bifunctional Lead ? Agonist / ? Antagonist Containing the Dmt-Tic Opioid Pharmacophore.  

PubMed

Based on a renewed importance recently attributed to bi- or multifunctional opioids, we report the synthesis and pharmacological evaluation of some analogues derived from our lead ? agonist / ? antagonist, H-Dmt-Tic-Gly-NH-Bzl. Our previous studies focused on the importance of the C-teminal benzyl function in the induction of such bifunctional activity. The introduction of some substituents in the para position of the phenyl ring (-Cl, -CH(3), partially -NO(2), inactive -NH(2)) was found to give a more potent ? agonist / antagonist effect associated with a relatively unmodified ? antagonist activity (pA(2) = 8.28-9.02). Increasing the steric hindrance of the benzyl group (using diphenylmethyl and tetrahydroisoquinoline functionalities) substantially maintained the ? agonist and ? antagonist activities of the lead compound. Finally and quite unexpectedly D-Tic2, considered as a wrong opioid message now; inserted into the reference compound in lieu of L-Tic, provided a ? agonist / ? agonist better than our reference ligand (H-Dmt-Tic-Gly-NH-Ph) and was endowed with the same pharmacological profile. PMID:20352071

Balboni, Gianfranco; Salvadori, Severo; Trapella, Claudio; Knapp, Brian I; Bidlack, Jean M; Lazarus, Lawrence H; Peng, Xuemei; Neumeyer, John L

2010-02-17

439

First report of a bifunctional chitinase/lysozyme produced by Bacillus pumilus SG2.  

PubMed

Bacillus pumilus SG2 isolated from high salinity ecosystem in Iran produces two chitinases (ChiS and ChiL) and secretes them into the medium. In this study, chiS and chiL genes were cloned in pQE-30 expression vector and were expressed in the cytoplasm of Escherichia coli strain M15. The recombinant proteins were purified using Ni-NTA column. The optimum pH and optimum temperature for enzyme activity of ChiS were pH 6, 50°C; those of ChiL were pH 6.5, 40°C. The purified chitinases showed antifungal activity against Fusarium graminearum, Rhizoctonia solani, Magnaporthe grisea, Sclerotinia sclerotiorum, Trichoderma reesei, Botrytis cinerea and Bipolaris sp. Moreover, purified ChiS was identified as chitinase/lysozyme, which are capable of degrading the chitin component of fungal cell walls and the peptidoglycan component of cell walls with many kinds of bacteria (Xanthomonas translucens pv. hordei, Xanthomonas axonopodis pv. citri, Bacillus licheniformis, E. coli C600, E. coli TOP10, Pseudomonas aeruginosa and Pseudomonas putida). Strong homology was found between the three-dimensional structures of ChiS and a chitinase/lysozyme from Bacillus circulans WL-12. This is the first report of a bifunctional chitinase/lysozyme from B. pumilus. PMID:22112904

Ghasemi, Seyedhadi; Ahmadian, Gholamreza; Sadeghi, Mehdi; Zeigler, Daniel R; Rahimian, Heshmatollah; Ghandili, Soheila; Naghibzadeh, Neda; Dehestani, Ali

2010-11-12

440

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.

Richter, G; Fischer, M; Krieger, C; Eberhardt, S; Luttgen, H; Gerstenschlager, I; Bacher, A

1997-01-01

441

Platinum-gold nanoparticles: a highly active bifunctional electrocatalyst for rechargeable lithium-air batteries.  

PubMed

PtAu nanoparticles (NPs) were shown to strongly enhance the kinetics of the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) in rechargeable Li-O(2) cells. Li-O(2) cells with PtAu/C were found to exhibit the highest round-trip efficiency reported to date. During ORR via xLi(+) + O(2) + xe(-) --> Li(x)O(2), the discharge voltage with PtAu/C was considerably higher than that of pure carbon and comparable to that of Au/C. During OER via Li(x)O(2) --> xLi(+) + O(2) + xe(-), the charge voltages with PtAu/C fell in the range from 3.4 to 3.8 V(Li), which is slightly lower than obtained with Pt. It is hypothesized that PtAu NPs exhibit bifunctional catalytic activity, having surface Au and Pt atoms primarily responsible for ORR and OER kinetics in Li-O(2) cells, respectively. PMID:20527774

Lu, Yi-Chun; Xu, Zhichuan; Gasteiger, Hubert A; Chen, Shuo; Hamad-Schifferli, Kimberly; Shao-Horn, Yang

2010-09-01

442

DEER EPR Measurements for Membrane Protein Structures via Bifunctional Spin Labels and Lipodisq Nanoparticles.  

PubMed

Pulsed EPR DEER structural studies of membrane proteins in a lipid bilayer have often been hindered by difficulties in extracting accurate distances when compared to those of globular proteins. In this study, we employed a combination of three recently developed methodologies, (1) bifunctional spin labels (BSL), (2) SMA-Lipodisq nanoparticles, and (3) Q band pulsed EPR measurements, to obtain improved signal sensitivity, increased transverse relaxation time, and more accurate and precise distances in DEER measurements on the integral membrane protein KCNE1. The KCNE1 EPR data indicated an ?2-fold increase in the transverse relaxation time for the SMA-Lipodisq nanoparticles when compared to those of proteoliposomes and narrower distance distributions for the BSL when compared to those of the standard MTSL. The certainty of information content in DEER data obtained for KCNE1 in SMA-Lipodisq nanoparticles is comparable to that in micelles. The combination of techniques will enable researchers to potentially obtain more precise distances in cases where the traditional spin labels and membrane systems yield imprecise distance distributions. PMID:23984855

Sahu, Indra D; McCarrick, Robert M; Troxel, Kaylee R; Zhang, Rongfu; Smith, Hubbell J; Dunagan, Megan M; Swartz, Max S; Rajan, Prashant V; Kroncke, Brett M; Sanders, Charles R; Lorigan, Gary A

2013-09-09

443

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

444

Static forces in a superconducting magnet bearing  

SciTech Connect

Static levitation forces and stiffnesses in a superconducting bearing consisting of concentric ring magnets and a superconducting YBaCuO ring are investigated. In the field-cooled mode a levitation force of 20 N has been achieved. The axial and radial stiffnesses have values of 15 N/mm and 10 N/mm, respectively. An arrangement with two bearings supporting a high speed shaft is now under development. A possible application of superconducting magnetic bearings is flywheels for energy storage.

Stoye, P.; Fuchs, G. [Institut fuer Festkoerper- und Werkstofforschung, Dresden (Germany); Gawalek, W.; Goernert, P. [Institut fuer Physikalische Hochtechnologie, Jena (Germany); Gladun, A. [Technische Univ., Dresden (Germany)

1995-11-01

445

Superconducting bearings with levitation control configurations  

SciTech Connect

This patent describes a superconducting rotating assembly. It comprises first and second bearing means comprising a material exhibiting superconducting properties; a rotatable member having two extremities aligned along a common axis; magnet means at each extremity; means for maintaining each the bearing means at a temperature where the superconducting properties are manifest; means for rotating the rotatable member; means for sensing the position of the rotatable member relative to each the bearing means; and means for controlling the levitation forces exerted on the rotatable member by each the bearing means.

Flom, Y.; Royston, J.D.

1992-05-26

446

Development of passive superconducting bearings. Phase 3  

NASA Astrophysics Data System (ADS)

This report documents the development of a passive superconducting bearing that is used to levitate relatively heavy rotors. This bearing was used to levitate a 7 lb rotor and spin at speeds of up to 12,000 rpm. The success of this effort indicates that the superconducting bearings have the potential for transition from a mere laboratory curiosity to a functional bearing component in a wider range of practical applications such as cryoturbopumps, miniature cryocoolers, and magnetic refrigerators. In addition, several configurations using superconductors to support loads along a single axis were investigated. The effort was directed to identify a specific configuration that offers a very high stiffness.

Rao, Dantam K.

1993-05-01

447

Nutrition Initiative  

Center for Food Safety and Applied Nutrition (CFSAN)

Text VersionPage 1. 9 / Health and Human Services / US Food and Drug Administration Nutrition Initiative Enforcement Letters The front ... More results from www.fda.gov/downloads/food/ingredientspackaginglabeling

448

Ceramic Bearing Development. Silicon Nitride Bearing Balls of Improved Reliability: Thermal Oxidation.  

National Technical Information Service (NTIS)

The major objective of this work was to improve the reliability of silicon nitride bearing balls by means of an optimized thermal oxidation treatment. Previous work had shown that the thermal fracture resistance of silicon nitride bearing balls increased ...

C. B. Burk

1996-01-01

449

Nuclear genomic sequences reveal that polar bears are an old and distinct bear lineage.  

PubMed

Recent studies have shown that the polar bear matriline (mitochondrial DNA) evolved from a brown bear lineage since the late Pleistocene, potentially indicating rapid speciation and adaption to arctic conditions. Here, we present a high-resolution data set from multiple independent loci across the nuclear genomes of a broad sample of polar, brown, and black bears. Bayesian coalescent analyses place polar bears outside the brown bear clade and date the divergence much earlier, in the middle Pleistocene, about 600 (338 to 934) thousand years ago. This provides more time for polar bear evolution and confirms previous suggestions that polar bears carry introgressed brown bear mitochondrial DNA due to past hybridization. Our results highlight that multilocus genomic analyses are crucial for an accurate understanding of evolutionary history. PMID:22517859

Hailer, Frank; Kutschera, Verena E; Hallström, Björn M; Klassert, Denise; Fain, Steven R; Leonard, Jennifer A; Arnason, Ulfur; Janke, Axel

2012-04-20

450

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

451

A bifunctional enzyme catalyzes the first two steps in N-acetylneuraminic acid biosynthesis of rat liver. Molecular cloning and functional expression of UDP-N-acetyl-glucosamine 2-epimerase/N-acetylmannosamine kinase.  

PubMed

N-Acetylneuraminic acid (Neu5Ac) is the precursor of sialic acids, a group of important molecules in biological recognition systems. Biosynthesis of Neu5Ac is initiated and regulated by its key enzyme, UDP-N-acetylglucosamine 2-epimerase (UDP-GlcNAc 2-epimerase, EC 5.1. 3.14)/N-acetylmannosamine kinase (ManNAc kinase, EC 2.7.1.60) in rat liver (Hinderlich, S., Stäsche, R., Zeitler, R., and Reutter, W. (1997) J. Biol. Chem. 272, 24313-24318). In the present paper we report the isolation and characterization of a cDNA clone encoding this bifunctional enzyme. An open reading frame of 2166 base pairs encodes 722 amino acids with a predicted molecular mass of 79 kDa. The deduced amino acid sequence contains exact matches of the sequences of five peptides derived from tryptic cleavage of the enzyme. The recombinant bifunctional enzyme was expressed in COS7 cells, where it displayed both epimerase and kinase activity. Distribution of UDP-GlcNAc 2-epimerase/ManNAc kinase in the cytosol of several rat tissues was investigated by determining both specific enzyme activities. Secreting organs (liver, salivary glands, and intestinal mucosa) showed high specific activities of UDP-GlcNAc 2-epimerase/ManNAc kinase, whereas significant levels of these activities were absent from other organs (lung, kidney, spleen, brain, heart, skeletal muscle, and testis). Northern blot analysis revealed no UDP-GlcNAc 2-epimerase/ManNAc kinase mRNA in the non-secreting tissues. PMID:9305888

Stäsche, R; Hinderlich, S; Weise, C; Effertz, K; Lucka, L; Moormann, P; Reutter, W

1997-09-26

452

Remote Detection of Bearing Fatigue Spalls via the Dynamic Response of Bearings on the Same Shaft  

Microsoft Academic Search

Turbine engine bearing failures are the leading mechanical cause of class-A failures. The most common mode of bearing failure in turbine engine applications is fatigue spalling. This paper describes a sensor capable of monitoring multiple bearings on a common shaft for the presence of fatigue spalls. Experimental data is presented demonstrating the ability of a single sensor installed on one

David Tow; Sean Marble

2007-01-01

453

Stability of Finite Journal Bearings–-from Linear and Nonlinear Bearing Forces  

Microsoft Academic Search

This 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

A. K. Tieu; Z. L. Qiu

1995-01-01

454

PERFORMANCE OF SYNCHRONOUS CONTROLLERS FOR ROTOR MAGNETIC BEARING SYSTEMS UNDER RETAINER BEARING CONTACT  

Microsoft Academic Search

Magnetic bearings provide frictionless, non-contact support of rotating machinery, but they have limited force generation capabilities and have to incorporate retainer bearings to protect the rotor and stator laminations if rotor vibration levels become excessive. The usual practice when the contact occurs is to shut down the system. The contact occurrence with retainer bearings is not restricted to power loss

M. N. Sahinkaya; A. G. Abulrub; P. S. Keogh

455

Precision instrumentation for rolling element bearing characterization  

SciTech Connect

This article describes an instrument to measure the error motion of rolling element bearings. This challenge is met by simultaneously satisfying four requirements. First, an axial preload must be applied to seat the rolling elements in the bearing races. Second, one of the races must spin under the influence of an applied torque. Third, rotation of the remaining race must be prevented in a way that leaves the radial, axial/face, and tilt displacements free to move. Finally, the bearing must be fixtured and measured without introducing off-axis loading or other distorting influences. In the design presented here, an air bearing reference spindle with error motion of less than 10 nm rotates the inner race of the bearing under test. Noninfluencing couplings are used to prevent rotation of the bearing outer race and apply an axial preload without distorting the bearing or influencing the measurement. Capacitive displacement sensors with 2 nm resolution target the nonrotating outer race. The error motion measurement repeatability is shown to be less than 25 nm. The article closes with a discussion of how the instrument may be used to gather data with sufficient resolution to accurately estimate the contact angle of deep groove ball bearings.

Marsh, Eric R.; Vigliano, Vincent C.; Weiss, Jeffrey R.; Moerlein, Alex W.; Vallance, R. Ryan [Machine Dynamics Research Laboratory, Pennsylvania State University, 331 Reber Building University Park, Pennsylvania 16802 (United States); Precision Systems Laboratory, George Washington University, 738 Phillips Hall 801 22nd Street, N.W. Washington, D.C., 20052 (United States)

2007-03-15

456

Methods and systems for micro bearings  

DOEpatents

A micro drive assembly may comprise a substrate, a micro shall oriented in-plane with the substrate and at least one micro bearing to support rotation of the micro shaft. The micro shaft and micro bearing may be in or less than the micrometer domain.

Stalford, Harold L.

2012-10-09

457

High temperature corrosion resistant bearing steel development  

Microsoft Academic Search

The aim towards increased power-to-weight ratios and reduced specific fuel consumption in advanced gas turbine engines demands mainshaft bearings that are able to operate under an increasingly severe environment. This environment includes higher temperatures, increased hoop stresses, and more rapid accumulation of stress cycles. In addition, corrosion currently accounts for approximately 30 percent of all bearing rejections during engine overhaul.

E. E. Pfaffenberger; P. Tarrantini

1993-01-01

458

Bearing Assembly for an Electrical Machine.  

National Technical Information Service (NTIS)

The bearing assembly differs from existing ones in that a bushing is fixed onto the shaft of the machine in order to increase sealing reliability. The butt end of the bushing from the side opposite the bearing is conical and mates with the seal. A rotatin...

A. S. Kozharin M. P. Bakumenko M. V. Babai Y. S. Marchuk

1972-01-01

459

Self-Feeding Fluid Film Bearings.  

National Technical Information Service (NTIS)

A concept is proposed for a fluid film bearing retainer (FFBR) which includes the following: (1) a reservoir in which excess lubricating fluid is stored; (2) a means of pumping the stored fluid from the reservoir to the bearing; (3) a seal to prevent loss...

C. H. T. Pan R. L. Smith

1982-01-01

460

Precision instrumentation for rolling element bearing characterization  

Microsoft Academic Search

This article describes an instrument to measure the error motion of rolling element bearings. This challenge is met by simultaneously satisfying four requirements. First, an axial preload must be applied to seat the rolling elements in the bearing races. Second, one of the races must spin under the influence of an applied torque. Third, rotation of the remaining race must

Eric R. Marsh; Vincent C. Vigliano; Jeffrey R. Weiss; Alex W. Moerlein; R. Ryan Vallance

2007-01-01

461

Precision instrumentation for rolling element bearing characterization  

NASA Astrophysics Data System (ADS)

This article describes an instrument to measure the error motion of rolling element bearings. This challenge is met by simultaneously satisfying four requirements. First, an axial preload must be applied to seat the rolling elements in the bearing races. Second, one of the races must spin under the influence of an applied torque. Third, rotation of the remaining race must be prevented in a way that leaves the radial, axial/face, and tilt displacements free to move. Finally, the bearing must be fixtured and measured without introducing off-axis loading or other distorting influences. In the design presented here, an air bearing reference spindle with error motion of less than 10 nm rotates the inner race of the bearing under test. Noninfluencing couplings are used to prevent rotation of the bearing outer race and apply an axial preload without distorting the bearing or influencing the measurement. Capacitive displacement sensors with 2 nm resolution target the nonrotating outer race. The error motion measurement repeatability is shown to be less than 25 nm. The article closes with a discussion of how the instrument may be used to gather data with sufficient resolution to accurately estimate the contact angle of deep groove ball bearings.

Marsh, Eric R.; Vigliano, Vincent C.; Weiss, Jeffrey R.; Moerlein, Alex W.; Vallance, R. Ryan

2007-03-01

462

BLACK BEAR DENNING ECOLOGY IN INTERIOR ALASKA  

Microsoft Academic Search

From 1988 to 1991 we observed the denning activity of 27 radio-collared black bears (Ursus americanus) at 57 dens on the Tanana River Flats, near Fairbanks, Alaska. This is the northernmost population of black bears studied using radio telemetry, and nears the northern extreme of their range. We compared differences in den chronology, morphology, and habitat use, among sex, age,

MARTIN E. SMITH; JOHN L. HECHTEL; ERICH H. FOLLMANN

463

Grease Degradation in Rolling Element Bearings  

Microsoft Academic Search

Grease is degraded during use in rolling element bearings and as a result the lubrication performance can deteriorate. Under severe conditions this can result in lubrication failure and, thus, the grease life will effectively limit the bearing life. At present there is a lack of detailed information regarding the changes that occur in the grease and the way in which

P. M. Cann; J. P. Doner; M. N. Webster; V. Wikstrom

2001-01-01

464

Space-filling bearings in three dimensions.  

PubMed

We present the first space-filling bearing in three dimensions. It is shown that a packing which contains only loops of an even number of spheres can be constructed in a self-similar way and that it can act as a three-dimensional bearing in which spheres can rotate without slip and with negligible torsion friction. PMID:14995378

Baram, R Mahmoodi; Herrmann, H J; Rivier, N

2004-01-30

465

29 CFR of - bearing Animals, or Poultry  

Code of Federal Regulations, 2010 CFR

...2010-07-01 false bearing Animals, or Poultry of Raising of Livestock, Bees, Fur Labor Regulations Relating to Labor (Continued...780.147; §§ 780.152 through 780.157. Raising of Livestock, Bees, Fur-bearing Animals, or...

2010-07-01

466

Further Evidence for Hibernation of Bears.  

National Technical Information Service (NTIS)

In the previous symposia on the Biology of Bears, we presented the argument that three species of bears undergo a form of dormancy which is in several senses more profound than in the typical or classical hibernators, such as woodchucks(Marmota monax) (Fo...

G. E. Folk J. M. Hunt M. A. Folk

1977-01-01

467

Improvement of bearing strength of laminated composites  

Microsoft Academic Search

Carbon fibre reinforced composite structures generally out perform metallic ones, but this is not the case when the structure is loaded in bearing. This work examines several different strategies for improving bearing performance. The first strategy was fibre steering (directed fibre placement). Three different methods were used to determine the trajectories for the steered fibres, referred to as the principal

A. Crosky; D. Kelly; R. Li; X. Legrand; N. Huong; R. Ujjin

2006-01-01

468

Dare to Care for a Grizzly Bear  

NSDL National Science Digital Library

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

Wnet

2008-11-18

469

Rotating shaft seal and bearing lubricating apparatus  

Microsoft Academic Search

In accordance with an illustrative embodiment of the present invention, a seal or bearing lubricating system adapted for use in a downhole tool such as a drilling motor includes chamber means packed with grease for lubricating said and\\/or bearing, and centrifugal separator means responsive to rotation of a shaft included in said tool for separating and trapping solid particles suspended

Young

1985-01-01

470

Diffusion of Water with Gummy Bears  

NSDL National Science Digital Library

In this activity, learners investigate the movement of water into and out of a polymer. Learners test the diffusion of water through gummy bears, which are made of sugar and gelatin (a polymer). Learners compare what happens when they put gummy bears are submerged in tap water versus distilled water.

Harris, Mary

2003-01-01

471

The Use of Glass Substrates with Bi-Functional Silanes for Designing Micropatterned Cell-Secreted Cytokine Immunoassays  

PubMed Central

It is often desirable to sequester cells in specific locations on the surface and to integrate sensing elements next to the cells. In the present study, surfaces were fabricated so as to position cytokine sensing domains inside non-fouling poly(ethylene glycol) (PEG) hydrogel microwells. Our aim was to increase sensitivity of micropatterned cytokine immunoassays through covalent attachment of biorecognition molecules. To achieve this, glass substrates were functionalized with a binary mixture of acrylate- and thiol-terminated methoxysilanes. During subsequent hydrogel photopatterning step acrylate moieties served to anchor hydrogel microwells to glass substrates. Importantly, glass attachment sites within the microwells contained thiol groups that could be activated with a hetero-bifunctional cross-linker for covalent immobilization of proteins. After incubation with fluorescently-labeled avidin, microwells fabricated on a mixed acryl/thiol silane layer emitted ~6 times more fluorescence compared to microwells fabricated on an acryl silane alone. This result highlighted the advantages of covalent attachment of avidin inside the microwells. To create cytokine immunoassays, micropatterned surfaces were incubated with biotinylated IFN-? or TNF-? antibodies (Abs). Micropatterned immunoassays prepared in this manner were sensitive down to 1 ng/ml or 60 pM IFN-?. To further prove utility of this bionterface design, macrophages were seeded into 30 µm diameter microwells fabricated on either bi-functional (acryl/thiol) or monofunctional silane layers. Both types of microwells were coated with avidin and biotin-anti-TNF-? prior to cell seeding. Short mitogenic activation followed by immunostaining for TNF-? revealed that microwells created on bi-functional silane layer had 3 times higher signal due to macrophage-secreted TNF-? compared to microwells fabricated on mono-functional silane. The rational design of cytokine-sensing surfaces described here will be leveraged in the future for rapid detection of multiple cytokines secreted by individual immune cells.

Seo, Jeong Hyun; Chen, Li-Jung; Verkhoturov, Stanislav V.; Schweikert, Emile A.; Revzin, Alexander

2011-01-01

472

Nested Arg-specific bifunctional crosslinkers for MS-based structural analysis of proteins and protein assemblies  

PubMed Central

The combination of chemical probing and high-resolution mass spectrometry constitutes a powerful alternative for the structural elucidation of biomolecules possessing unfavorable size, solubility, and flexibility. We have developed nested Arg-specific bifunctional crosslinkers to obtain complementary information to typical Cys- and Lys-specific reagents available on the market. The structures of 1,4-phenyl-diglyoxal (PDG) and 4,4?-biphenyl-diglyoxal (BDG) include two identical 1,2-dicarbonyl functions capable of reacting with the guanido group of Arg residues in proteins, as well as the base-pairing face of guanine in nucleic acids. The reactive functions are separated by modular spacers consisting of one or two benzene rings, which confer greater rigidity to the crosslinker structure than it is afforded by typical aliphatic spacers. Analysis by electrospray ionization (ESI) Fourier transform ion cyclotron resonance (FTICR) mass spectrometry has shown that the probes provide both mono- and bifunctional products with model protein substrates, which are stabilized by the formation of diester derivatives in the presence of borate buffer. The identification of crosslinked sites was accomplished by employing complementary proteolytic procedures and peptide mapping by ESI-FTICR. The results showed excellent correlation with the solvent accessibility and structural context of susceptible residues, and highlighted the significance of possible dynamic effects in determining the outcome of crosslinking reactions. The application of nested reagents with different spacing has provided a new tool for experimentally recognizing flexible regions that may be involved in prominent dynamics in solution. The development of new bifunctional crosslinkers with diverse target specificity and different bridging spans is expected to facilitate the structure elucidation of progressively larger biomolecular assemblies by increasing the number and diversity of spatial constraints available for triangulating the position of crosslinked structures in the three dimensions.

Zhang, Qingrong; Crosland, Elizabeth; Fabris, Daniele

2009-01-01

473

Single-mismatch position-sensitive detection of DNA based on a bifunctional ruthenium complex.  

PubMed

A ruthenium complex, pentaamine ruthenium [3-(2-phenanthren-9-yl-vinyl)-pyridine] (which we refer to as RuL in the text) generated in situ has been used as a sensitive and selective electrochemical indicator in DNA sensing. The complex incorporates dual functionalities with the Ru center providing a redox probe and the ligand (L) providing a fluorescent tag. The presence of the aromatic groups in the ligand endows the complex with an intercalative character and makes it capable of binding to double-stranded DNA (dsDNA) more efficiently than to single-stranded DNA (ssDNA). Combining spectroscopic and electrochemical techniques, we have elucidated the nature of the interactions. From these data we conclude that the binding mode is fundamentally intercalative. The ligand-based fluorescence allows characterization of the complex formation as well as for melting experiments to be carried out. The metal-based redox center is employed as an electrochemical indicator to detect the hybridization event in a DNA biosensor. The biosensor has been developed by immobilization of a thiolated capture probe sequence from Helicobacter pylori onto gold electrodes. With the use of this approach, complementary target sequences of Helicobacter can be quantified over the range of 106 to 708 pmol with a detection limit of 92+/-0.4 pmol and a linear correlation coefficient of 0.995. In addition, this approach allows the detection, without the need for a hybridization suppressor in solution, such as formamide, of not only a single mismatch but also its position in a specific sequence of H. pylori, due to the selective interaction of this bifunctional ruthenium complex with dsDNA. PMID:18031019

García, T; Revenga-Parra, M; Abruña, H D; Pariente, F; Lorenzo, E

2007-11-22

474

Synthesis and Evaluation of Bifunctional sGC Regulators: Optimization of a Connecting Linker.  

PubMed

Hybrid molecules composed of PpIX and cobyrinic acid derivatives conjugated through linkers of varying length and composition were prepared via 1,3-dipolar cycloaddition (CuAAC) or amidation/esteryfication reactions. They were tested for activation of soluble guanylyl cyclase (sGC), a key enzyme in the NO/cGMP signaling pathway, by an in vitro GTP?cGMP conversion assay. Using purified heme-deficient sGC and truncated sGC variants lacking a heme-binding domain, we demonstrated that such hybrid molecules may activate sGC by targeting heme-binding and/or catalytic domain. While all conjugates activated sGC, only selected compounds served as bifunctional regulators and were capable of simultaneous targeting both heme and catalytic domains of sGC. The length and type of a linker connecting both components had a profound effect on the extent of sGC activation, indicating that the linker's type is crucial for their binding affinities with regulatory and catalytic domains. Only hybrids with the conjugated linker of 13-16 atom length synergistically target both domains and displayed the lowest EC50 and highest activating potency. Compounds with shorter connecting linkers were much less potent and were no more active than the cobyrinic acid component alone. The most active conjugate, which showed a 60-fold activation of sGC, was compound 11, in which PpIX and cobyrinic acid components are separated by 11 atoms chain with the triazole moiety in between. PMID:23961771

Chromi?ski, Miko?aj; Banach, Lukasz; Karczewski, Maksymilian; O Proinsias, Keith; Sharina, Iraida; Gryko, Dorota; Martin, Emil

2013-09-10

475

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

476