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1

Adaptation de la separation cryomagnetique aux technologies de l'environnement: application a l'epuration d'effluents liquides industriels. (Cryo magnetic separation adaptation to environment technologies: application to industrial effluents).  

National Technical Information Service (NTIS)

Cryomagnetic separation adaptation to environment technologies application to industrial liquid effluents. The performance, obtained by superconducting high filed - high gradient magnetic separation, permitted to foresee the magnetic treatment of heavy me...

V. Bureau

1993-01-01

2

A magnetic resonance (MR) microscopy system using a microfluidically cryo-cooled planar coil.  

PubMed

We present the development of a microfluidically cryo-cooled planar coil for magnetic resonance (MR) microscopy. Cryogenically cooling radiofrequency (RF) coils for magnetic resonance imaging (MRI) can improve the signal to noise ratio (SNR) of the experiment. Conventional cryostats typically use a vacuum gap to keep samples to be imaged, especially biological samples, at or near room temperature during cryo-cooling. This limits how close a cryo-cooled coil can be placed to the sample. At the same time, a small coil-to-sample distance significantly improves the MR imaging capability due to the limited imaging depth of planar MR microcoils. These two conflicting requirements pose challenges to the use of cryo-cooling in MR microcoils. The use of a microfluidic based cryostat for localized cryo-cooling of MR microcoils is a step towards eliminating these constraints. The system presented here consists of planar receive-only coils with integrated cryo-cooling microfluidic channels underneath, and an imaging surface on top of the planar coils separated by a thin nitrogen gas gap. Polymer microfluidic channel structures fabricated through soft lithography processes were used to flow liquid nitrogen under the coils in order to cryo-cool the planar coils to liquid nitrogen temperature (-196 °C). Two unique features of the cryo-cooling system minimize the distance between the coil and the sample: (1) the small dimension of the polymer microfluidic channel enables localized cooling of the planar coils, while minimizing thermal effects on the nearby imaging surface. (2) The imaging surface is separated from the cryo-cooled planar coil by a thin gap through which nitrogen gas flows to thermally insulate the imaging surface, keeping it above 0 °C and preventing potential damage to biological samples. The localized cooling effect was validated by simulations, bench testing, and MR imaging experiments. Using this cryo-cooled planar coil system inside a 4.7 Tesla MR system resulted in an average image SNR enhancement of 1.47 ± 0.11 times relative to similar room-temperature coils. PMID:21603723

Koo, Chiwan; Godley, Richard F; Park, Jaewon; McDougall, Mary P; Wright, Steven M; Han, Arum

2011-05-23

3

Magnetic Separation Device.  

National Technical Information Service (NTIS)

This invention pertains to magnetic separation devices and more particularly to; magnetic separation devices used to selectively remove magnetic bead-coated cells from tissues such as bone marrow or blood. Depletion of cell populations from boner marrow h...

G. M. Starken J. Cavin R. A. Quinnell C. A. Twigg D. P. Crawford

1985-01-01

4

A 10 T cryo-cooled superconducting magnet with 100 mm room temperature bore  

Microsoft Academic Search

A cryo-cooled NbTi\\/Nb3Sn superconducting magnet has been fabricated. It generated 10T field in the center of a 100 mm room temperature bore. A 4K GM refrigerator, using Er3Ni regenerator material, cooled the magnet without help of liquid helium. Heat generated in coils is removed through the heat conduction copper cylinder attached on the outer wall of each coil. Bi(2212) superconducting

M. Urata; K. Koyanagi; T. Kuriyama; K. Yamamoto; S. Nakayama; T. Yazawa; S. Nomura; Y. Yamada; H. Nakagome; S. Murase; H. Maeda; O. Horigami

1996-01-01

5

Magnetic separation anxiety  

SciTech Connect

This paper reports that only a few years ago superconducting magnetic separation was viewed as the next major market for superconducting magnets. The first commercial units had been installed, worked flawlessly, and demonstrated real economic viability. The potential market was seen as quite large, and many people believed that superconducting magnetic separation would soon show the same rapid growth that MRI had demonstrated after its initial success. These hopes even prompted IGC, one of the top MRI magnet builders, to form a separate division devoted to magnetic separation. Despite the existence of Magstream, IGC has not been overly active in the market. As a technology that has applications from the clay on the Earth to the soil on the moon, superconducting magnetic separation has yet to become widely used.

Canning, C.

1992-01-01

6

Superconducting magnetic separation  

SciTech Connect

The initially high hopes of a speedy replacement of conventional magnetic separators by superconducting ones have not been realised. The reasons for this are complex, ranging from the conservative nature of the mineral processing industry to insufficient cryogenic reliability and poor magnet design. The major systems delivered to industry will be described and some possible future developments will be outlined.

Kopp, J.

1988-03-01

7

Fabrication of fully dense nanostructured MnBi magnet by hot compaction of cryo-milled powders  

NASA Astrophysics Data System (ADS)

Recently, rare-earth-free permanent magnets (REFPMs) have attracted much attention globally owing to rare-earth metal crisis and high cost. Among the REFPMs, MnBi is a potential candidate due to its unusual large magnetocrystalline anisotropy (K 10^7 erg/cc) and positive temperature of coefficient of coercivity. In this work, we report for the first time a novel processing method that combines the cryo-milling with hot compaction to produce fully dense bulk nanostructured MnBi magnet. The effect of cryo-milling on particle size, phase formation, and magnetic properties of MnBi has been studied in detail. Also, the microstructural and magnetic properties of bulk nanostructured MnBi magnet were investigated. Adoption of cryo-milling results in nanocrystalline powders with particle size of 400-500 nm. Large coercivity (Hc) values of 18.5 kOe, and 12.9 kOe were obtained in cryo-milled powders and hot compacted magnet respectively. The MnBi magnet shows a large positive temperature coefficient of Hc and the Hc reaches a value of more than 30 kOe above 450 K.

Hadjipanayis, George; Ramarao Neelam, Venkata; Gabay, Alex; Li, Wang

2013-03-01

8

Magnetic separation for soil decontamination  

SciTech Connect

High gradient magnetic separation (HGMS) is a physical separation process that is used to extract magnetic particles from mixtures. The technology is used on a large scale in the kaolin clay industry to whiten or brighten kaolin clay and increase its value. Because all uranium and plutonium compounds are slightly magnetic, HGMS can be used to separate these contaminants from non-magnetic soils. A Cooperative Research and Development Agreement (CRADA) was signed in 1992 between Los Alamos National Laboratory (LANL) and Lockheed Environmental Systems and Technologies Company (LESAT) to develop HGMS for soil decontamination. This paper reports progress and describes the HGMS technology.

Avens, L.R.; Worl, L.A.; deAguero, K.J.; Padilla, D.D.; Prenger, F.C.; Stewart, W.F.; Hill, D.D. (Los Alamos National Lab., NM (United States)); Tolt, T.L. (Lockheed Environmental Systems and Technologies (United States))

1993-01-01

9

Magnetic separation for soil decontamination  

SciTech Connect

High gradient magnetic separation (HGMS) is a physical separation process that is used to extract magnetic particles from mixtures. The technology is used on a large scale in the kaolin clay industry to whiten or brighten kaolin clay and increase its value. Because all uranium and plutonium compounds are slightly magnetic, HGMS can be used to separate these contaminants from non-magnetic soils. A Cooperative Research and Development Agreement (CRADA) was signed in 1992 between Los Alamos National Laboratory (LANL) and Lockheed Environmental Systems and Technologies Company (LESAT) to develop HGMS for soil decontamination. This paper reports progress and describes the HGMS technology.

Avens, L.R.; Worl, L.A.; deAguero, K.J.; Padilla, D.D.; Prenger, F.C.; Stewart, W.F.; Hill, D.D. [Los Alamos National Lab., NM (United States); Tolt, T.L. [Lockheed Environmental Systems and Technologies (United States)

1993-02-01

10

Continuous magnetic separator and process  

DOEpatents

A continuous magnetic separator and process for separating a slurry comprising magnetic particles into a clarified stream and a thickened stream. The separator has a container with a slurry inlet, an overflow outlet for the discharge of the clarified slurry stream, and an underflow outlet for the discharge of a thickened slurry stream. Magnetic particles in the slurry are attracted to, and slide down, magnetic rods within the container. The slurry is thus separated into magnetic concentrate and clarified slurry. Flow control means can be used to control the ratio of the rate of magnetic concentrate to the rate of clarified slurry. Feed control means can be used to control the rate of slurry feed to the slurry inlet.

Oder, Robin R. (Export, PA); Jamison, Russell E. (Lower Burrell, PA)

2008-04-22

11

Magnetic separation for environmental remediation  

SciTech Connect

High Gradient Magnetic Separation (HGMS) is a form of magnetic separation used to separate solids from other solids, liquids or gases. HGMS uses large magnetic field gradients to separate ferromagnetic and paramagnetic particles from diamagnetic host materials. The technology relies only on physical properties, and therefore separations can be achieved while producing a minimum of secondary waste. Actinide and fission product wastes within the DOE weapons complex pose challenging problems for environmental remediation. Because the majority of actinide complexes and many fission products are paramagnetic, while most host materials are diamagnetic, HGMS can be used to concentrate the contaminants into a low volume waste stream. The authors are currently developing HGMS for applications to soil decontamination, liquid waste treatment, underground storage tank waste treatment, and actinide chemical processing residue concentration. Application of HGMS usually involves passing a slurry of the contaminated mixture through a magnetized volume. Field gradients are produced in the magnetized volume by a ferromagnetic matrix material, such as steel wool, expanded metal, iron shot, or nickel foam. The matrix fibers become trapping sites for ferromagnetic and paramagnetic particles in the host material. The particles with a positive susceptibility are attracted toward an increasing magnetic field gradient and can be extracted from diamagnetic particles, which react in the opposite direction, moving away from the areas of high field gradients. The extracted paramagnetic contaminants are flushed from the matrix fibers when the magnetic field is reduced to zero or when the matrix canister is removed from the magnetic field. Results are discussed for the removal of uranium trioxide from water, PuO{sub 2}, U, and Pu from various soils (Fernald, Nevada Test Site), and the waste water treatment of Pu and Am isotopes using HGMS.

Schake, A.R.; Avens, L.R.; Hill, D.D.; Padilla, D.D.; Prenger, F.C.; Romero, D.A.; Worl, L.A. [Los Alamos National Lab., NM (United States); Tolt, T.L. [Lockheed Environmental Systems and Technologies Co., Las Vegas, NV (United States)

1994-11-01

12

Separation of magnetic field lines  

SciTech Connect

The field lines of magnetic fields that depend on three spatial coordinates are shown to have a fundamentally different behavior from those that depend on two coordinates. Unlike two-coordinate cases, a flux tube in a magnetic field that depends on all three spatial coordinates that has a circular cross section at one location along the tube characteristically has a highly distorted cross section at other locations. In an ideal evolution of a magnetic field, the current densities typically increase. Crudely stated, if the current densities increase by a factor {sigma}, the ratio of the long to the short distance across a cross section of a flux tube characteristically increases by e{sup 2{sigma}}, and the ratio of the longer distance to the initial radius increases as e{sup {sigma}}. Electron inertia prevents a plasma from isolating two magnetic field structures on a distance scale shorter than c/{omega}{sub pe}, which is about 10 cm in the solar corona, and reconnection must be triggered if {sigma} becomes sufficiently large. The radius of the sun, R{sub Circled-Dot-Operator }=7 Multiplication-Sign 10{sup 10}cm is about e{sup 23} times larger, so when {sigma} Greater-Than-Or-Equivalent-To 23, two lines separated by c/{omega}{sub pe} at one location can be separated by the full scale of any magnetic structures in the corona at another. The conditions for achieving a large exponentiation, {sigma}, are derived, and the importance of exponentiation is discussed.

Boozer, Allen H. [Department of Applied Physics and Applied Mathematics, Columbia University, New York, New York 10027 (United States)

2012-11-15

13

Magnetic separation of antibiotics by electrochemical magnetic seeding  

Microsoft Academic Search

Magnetic separation of several classes of antibiotics was investigated using electrochemical magnetic seeding. Electrocoagulation with a sacrificial anode followed by addition of magnetite particles was applied for the magnetic seeding of antibiotics. With electrochemical magnetic seeding using an iron anode, tetracycline antibiotics (oxytetracycline, chlortetracycline, doxycycline and tetracycline) and cephalosporin antibiotic (cefdinir) were rapidly removed from synthetic wastewater by magnetic separation

I. Ihara; K. Toyoda; N. Beneragama; K. Umetsu

2009-01-01

14

High gradient magnetic separation using superconducting bulk magnets  

NASA Astrophysics Data System (ADS)

We aim to apply the superconducting bulk magnets to high gradient magnetic separation technique. Two bulk magnets are face-to-face arranged and a pipe stuffed magnetic filters composed of ferromagnetic wires is placed between the magnetic poles. We setup the magnetic separation system and test it using slurry mixed with hematite particles (Fe2O3). Y123 bulk superconductors are magnetized by the ``IMRA'' method (pulsed-field magnetization), and consequently a magnetic field of 1.59 T is generated at the center of 20 mm gap between the magnetic poles. As a result of experiment on the magnetic separation, hematite particles of over 90% were removed from slurry at the flow rate of 2 l/min.

Yokoyama, K.; Oka, T.; Okada, H.; Noto, K.

2003-10-01

15

COAL CLEANING BY HIGH GRADIENT MAGNETIC SEPARATION  

Microsoft Academic Search

Results of experimental work on HGMS coal c leaning will be presented with emphasis on the r elation between cleaning results and coal characteristics. I INTRODUCTION High Gradient Magnetic Separation (HGMS) is a particle separation technique which is based on the differences in the magnetic properties of the particles. A survey of the principles, theory, experimental work and applications has

C. P. van Driel; J. Sikkenga; C. B. W. Kerkdijk

1984-01-01

16

Magnetic separation techniques: their application to medicine  

Microsoft Academic Search

Whilst separation techniques relying on gravitational forces have become relatively sophisticated in their application to biology the same is not true for magnetic separation procedures. The use of the latter has been limited to the few cells which contain paramagnetic iron. However with the development of several different types of magnetic particles and selective delivery system (e.g. monoclonal antibodies) the

J. T. Kemsheadl; J. Ugelstad

1985-01-01

17

The magnets of the GSI fragment separator  

SciTech Connect

The Fragment Separator is a device for producing and separating exotic nuclear beams. The exotic nuclei can be investigated directly, or the secondary beams can be injected into the storage-cooler ring, or delivered to targets in the experimental caves. The magnets of the spectrometer and the equipment used to measure the magnetic fields are described. Results of the measurements and operational experience with the laminated magnets are reported.

Langenbeck, B.; Gaiser, H.; Geissel, H.; Klos, F.; Moritz, G.; Muenzenberg, G.; Zweig, K. (GSI, Darmstadt (Germany))

1994-07-01

18

Magnetic separation of ferrihydrite from wastewater by magnetic seeding and high-gradient magnetic separation  

Microsoft Academic Search

Ferrihydrite, a member of iron oxides family, has been used as an adsorbent for the removal of heavy metal ions from industrial wastewater. The success of the operation depends mainly on the efficient removal of ferrihydrite from the aqueous phase. Hence, the emphasis of this study was given on the separation of ferrihydrite by high-gradient magnetic separator (HGMS) to overcome

Nuray Karapinar

2003-01-01

19

Magnetic separation of uranium from magnesium fluoride  

SciTech Connect

The attraction or repulsion of particles by a magnetic gradient, based on the respective susceptibilities, provides the basis for physical separation of particles that are comprised predominantly of uranium from those that are predominantly magnesium fluoride (MgF/sub 2/). To determine the effectiveness of this approach, a bench-scale magnetic separator from the S.G. Frantz Co., Inc. was used. In the Frantz Model L-1, particles are fed through a funnel onto a vibration tray and through a magnetic field. The specific design of the Frantz magnet causes the magnetic field strength to vary along the width of the magnet, setting up a gradient. The tray in the magnetic field is split at a point about half way down its length so that the separated material does not recombine. A schematic is presented of Frantz Model L-1 CN - the same magnet configured for high gradient magnetic separation of liquid-suspended particles. Here different pole pieces create a uniform magnetic field, and stainless steel wood in the canister between the pole pieces creates the high gradient. 1 ref., 6 figs., 2 tabs.

Hoegler, J.M.

1987-01-01

20

Reciprocating Magnetic Separator. Final Report.  

National Technical Information Service (NTIS)

In 2001, under DOE's Superconductivity Partnership Initiative (SPI), E. I. du Pont de Nemours & Co. (Dupont) was awarded a cost-share contract to build a fully functional full-scale model high temperature superconducting reciprocating magnet unit specific...

2008-01-01

21

High gradient magnetic separation using a high temperature superconducting magnet  

Microsoft Academic Search

We report on the operation and testing of a high temperature superconducting (HTS) high gradient magnetic separator (HGMS). The separator magnet is made of 624m of Silver\\/BSCCO HTS wire and has overall dimensions of 18cm OD, 15.5cm height and 5cm ID. HTS current leads are used to reduce the heat leak to the magnet. The system operates in a vacuum

J. A Selvaggi; D. L Cottrell; T. H Falconer; M. A Daugherty; D. E Daney; D. D Hill; F. C Prenger

1998-01-01

22

Magnetic separation in water pollution control  

Microsoft Academic Search

Magnetic separation as applied to waterborne contaminants is successful in reducing the solids content of a water sample and in removing the dissolved orthophosphate from the aqueous slurry. The contaminants are chemically associated with a magnetic seeding material, and subsequent removal of this seed sweeps the pollutants from the system. The advantage of this form of treatment over conventional techniques

CHRISTOPHER DE LATOUR

1973-01-01

23

HTS High Gradient Magnetic Separation system  

SciTech Connect

We report on the assembly, characterization and operation of a high temperature superconducting (HTS) magnetic separator. The magnet is made of 624 m of Silver/BSCCO superconducting wire and has overall dimensions of 18 cm OD, 15.5 cm height and 5 cm ID. The HTS current leads are designed to operate with the warm end at 75 K and the cold end cooled by a two stage Gifford-McMahon cryocooler. The upper stage of the cryocooler cools the thermal shield and two heat pipe thermal intercepts. The lower stage of the cryocooler cools the HTS magnet and the bottom end of the HTS current leads. The HTS magnet was initially characterized in liquid cryogens. We report on the current- voltage (I-V) characteristics of the HTS magnet at temperatures ranging from 15 to 40 K. At 40 K the magnet can generate a central field of 2.0 T at a current of 120 A.

Daugherty, M.A.; Coulter, J.Y.; Hults, W.L. [and others

1996-09-01

24

Development of magnetic separation system of magnetoliposomes  

NASA Astrophysics Data System (ADS)

The magnetic separation technology using sub-microsized ferromagnetic particle is indispensable in many areas of medical biosciences. For example, ferromagnetic particles (200-500 nm) are widely used for cell sorting in stem cell research with the use of cell surface-specific antigens. Nanosized ferromagnetic particles (10-20 nm) have been suggested as more suitable in drug delivery studies given their efficiency of tissue penetration, however, the magnetic separation method for them has not been established. One of the major reasons is that magnetic force acting on the object particles decreases drastically as a particle diameter becomes small. In this study, magnetic force acting on the targets was enhanced by the combination of superconducting magnet and the filter consisting of ferromagnetic particle. By doing so, we confirmed that Fe3O4 of 20 nm in diameter was trapped in the magnetic filter under an external magnetic field of 0.5 T. Fe3O4 encapsulated with phospholipid liposomes of 200 nm in diameter was also shown to be trapped as external magnetic field of 1.5 T, but not of 0.5 T. We also showed the result of particle trajectory calculation which emulated well the experimental data.

Nakao, R.; Matuo, Y.; Mishima, F.; Taguchi, T.; Maenosono, S.; Nishijima, S.

2009-10-01

25

High-gradient magnetic separation of coated magnetic nanoparticles  

Microsoft Academic Search

The feasibility is examined of using high-gradient magnetic separation (HGMS) to recover about 8-nm magnetite nanoparticles that are tailored specifically to extract target solutes (polymer-coated nanoparticles for the extraction of soluble organic contaminants from water and phospholipid-coated particles for the selective extraction of proteins). A general model for nanoparticle capture based on calculating the limit of static nanopar- ticle buildup

Geoffrey D. Moeser; Kaitlin A. Roach; William H. Green; T. Alan Hatton; Paul E. Laibinis

2004-01-01

26

Beneficiation with Magnetic Fluids—Magnetic Separation of the Second Kind  

Microsoft Academic Search

Colloidal solutions of magnetite placed in a magnetic field have been used to segregate nonmagnetic materials such as nonferrous scrap metals and to concentrate precious minerals. Conventional magnetic separation relies on the inherent magnetic susceptibility of the material to be separated and may be designated as magnetic separation of the first kind. When the medium of separation rather than the

S. E. KHALAFALLA

1985-01-01

27

CryoMACS Freezing Bag  

Center for Biologics Evaluation and Research (CBER)

... CryoMACS Freezing Bag. Applicant: Miltenyi Biotec, Incorporated. 510(k) number: BK090020. Product: CryoMACS Freezing Bag. ... More results from www.fda.gov/biologicsbloodvaccines/bloodbloodproducts/approvedproducts

28

Towards atomic resolution structural determination by single-particle cryo-electron microscopy  

PubMed Central

Recent advances in cryo-electron microscopy and single-particle reconstruction (collectively referred to as “cryoEM”) have made it possible to determine the three-dimensional (3D) structures of several macromolecular complexes at near-atomic resolution (~3.8 – 4.5 Å). These achievements were accomplished by overcoming challenges in sample handling, instrumentation, image processing, and model building. At near-atomic resolution, many detailed structural features can be resolved, such as the turns and deep grooves of helices, strand separation in ? sheets, and densities for loops and bulky amino acid side chains. Such structural data of the cytoplasmic polyhedrosis virus (CPV), the Epsilon 15 bacteriophage and the GroEL complex have provided valuable constraints for atomic model building using integrative tools, thus significantly enhancing the value of the cryoEM structures. The CPV structure revealed a drastic conformational change from a helix to a ? hairpin associated with RNA packaging and replication, coupling of RNA processing and release, and the long sought-after polyhedrin-binding domain. These latest advances in single-particle cryoEM provide exciting opportunities for the 3D structural determination of viruses and macromolecular complexes that are either too large or too heterogeneous to be investigated by conventional X-ray crystallography or nuclear magnetic resonance (NMR) methods.

Zhou, Z. Hong

2009-01-01

29

Modeling High Gradient Magnetic Separation in Biological Fluids  

NASA Astrophysics Data System (ADS)

A portable magnetic filter capable of separating magnetic nanospheres from arterial blood flow for detoxification of human blood is under design. In the separator design, an array of biocompatible capillary tubing and magnetizable wires is immersed into an externally applied homogeneous magnetic field. While subject to the magnetic field, the wires create high magnetic field gradients, which aid in the collection of blood- borne magnetic nanospheres from blood flow. In this study, a numerical model was created to determine the configuration of the wire-tubing array from two possible configurations. To determine which configuration was better suited for the separator design, the numerical capture efficiencies of the separator for the different configurations were compared over a range of mean blood flow velocities using subsets of the full configurations and compared with experimental results. For the configuration that showed higher capture efficiencies, the effects of blood velocity, magnetic field strength, wire and particle materials, and the length of the separator is also studied.

Bockenfeld, D.; Chen, H.; Rempfer, D.; Kaminski, M.; Rosengart, A.

2006-11-01

30

MSWI boiler fly ashes: magnetic separation for material recovery.  

PubMed

Nowadays, ferrous materials are usually recovered from Municipal Solid Waste Incineration (MSWI) bottom ash by magnetic separation. To our knowledge, such a physical technique has not been applied so far to other MSWI residues. This study focuses thus on the applicability of magnetic separation on boiler fly ashes (BFA). Different types of magnet are used to extract the magnetic particles. We investigate the magnetic particle composition, as well as their leaching behaviour (EN 12457-1 leaching test). The magnetic particles present higher Cr, Fe, Mn and Ni concentration than the non-magnetic (NM) fraction. Magnetic separation does not improve the leachability of the NM fraction. To approximate industrial conditions, magnetic separation is also applied to BFA mixed with water by using a pilot. BFA magnetic separation is economically evaluated. This study globally shows that it is possible to extract some magnetic particles from MSWI boiler fly ashes. However, the magnetic particles only represent from 23 to 120 g/kg of the BFA and, though they are enriched in Fe, are composed of similar elements to the raw ashes. The industrial application of magnetic separation would only be profitable if large amounts of ashes were treated (more than 15 kt/y), and the process should be ideally completed by other recovery methods or advanced treatments. PMID:21306886

De Boom, Aurore; Degrez, Marc; Hubaux, Paul; Lucion, Christian

2011-02-08

31

Fundamental study of phosphor separation by controlling magnetic force  

NASA Astrophysics Data System (ADS)

The phosphor wastes consist of phosphors with different emission colors, green (LAP), red (YOX), blue (BAM) and white (HP). It is required to recover and reuse the rare earth phosphors with high market value. In this study, we tried to separate the phosphor using the magnetic separation by HTS bulk magnet utilizing the differences of magnetic susceptibility by the type of phosphors. We succeeded in the successive separation of HP with low market value from YOX and BAM including the rare earth using the magnetic Archimedes method. In this method, vertical and radial components of the magnetic force were used.

Wada, Kohei; Mishima, Fumihito; Akiyama, Yoko; Nishijima, Shigehiro

2013-11-01

32

Integrated acoustic and magnetic separation in microfluidic channels  

PubMed Central

With a growing number of cell-based biotechnological applications, there is a need for particle separation systems capable of multiparameter separations at high purity and throughput, beyond what is presently offered by traditional methods including fluorescence activated cell sorting and column-based magnetic separation. Toward this aim, we report on the integration of microfluidic acoustic and magnetic separation in a monolithic device for multiparameter particle separation. Using our device, we demonstrate high-purity separation of a multicomponent particle mixture at a throughput of up to 108 particles?hr.

Adams, Jonathan D.; Thevoz, Patrick; Bruus, Henrik; Soh, H. Tom

2009-01-01

33

Waste Remediation Using in Situ Magnetically Assisted Chemical Separation  

Microsoft Academic Search

The magnetically assisted chemical separation process (MACS) combines the selective and efficient separation afforded by chemical sorption with the magnetic recovery of ferromagnetic particles. This process is being developed for treating the underground storage tanks at Hanford. These waste streams contain cesium, strontium, and transuranics (TRU) that must be removed before this waste can be disposed of as grout. The

L. Nuñez; B. A. Buchholz; G. F. Vandegrift

1995-01-01

34

Waste remediation using in situ magnetically assisted chemical separation  

Microsoft Academic Search

The magnetically assisted chemical separation process (MACS) combines the selective and efficient separation afforded by chemical sorption with the magnetic recovery of ferromagnetic particles. This process is being developed for treating the underground storage tanks at Hanford. These waste streams contain cesium, strontium, and transuranics (TRU) that must be removed before this waste can be disposed of as grout. The

L. Nunez; B. A. Buchholz; G. F. Vandegrift

1993-01-01

35

High gradient magnetic separation applied to environmental remediation  

SciTech Connect

High Gradient Magnetic Separation (HGMS) is an application of superconducting magnet technology to the separation of magnetic solids from other solids, liquids, or gases. The production of both high magnetic fields (>4 T) and large field gradients using superconducting magnet technology has made it possible to separate a previously unreachable but large family of paramagnetic materials. This is a powerful technique that can be used to separate widely dispersed contaminants from a host material and may be the only technique available for separating material in the colloidal state. Because it is a physical separation process, no additional waste is generated. We are applying this technology to the treatment of radioactive wastes for environmental remediation. We have conducted tests examining slurries containing nonradioactive, magnetic surrogates. Results from these studies were used to verify our analytical model of the separation process. The model describes the rate process for magnetic separation and is based on a force balance on the paramagnetic species. This model was used to support bench scale experiments and prototype separator design.

Prenger, F.C.; Stewart, W.F.; Hill, D.D.; Avens, L.R.; Worl, L.A.; Schake, A.; de Aguero, K.J.; Padilla, D.D. [Los Alamos National Lab., NM (United States); Tolt, T.L. [Lockheed Environmental Systems and Technology Co., Inc., Las Vegas, NV (United States)

1993-08-01

36

Magnetically separable composite photocatalyst with enhanced photocatalytic activity.  

PubMed

A novel magnetically separable composite photocatalyst, anatase titania-coated magnetic activated carbon (TMAC), was prepared in this article. In the synthesis, magnetic activated carbon (MAC) was firstly obtained by adsorbing magnetic Fe3O4 nanoparticles onto the activated carbon (AC), and then the obtained MAC was directly coated by anatase titania nanoparticles prepared at low temperature (i.e. 75 degrees C). The prepared samples were characterized by XRD, SEM and vibrating sample magnetometer (VSM). The composite photocatalyst can be easily separated from solution by a magnet, its photocatalytic activity in degradation of phenol in aqueous solution also has dramatic enhancement compared to that of the neat titania. PMID:18406055

Ao, Yanhui; Xu, Jingjing; Shen, Xunwei; Fu, Degang; Yuan, Chunwei

2008-03-08

37

Phase separation in aqueous magnetic colloidal solutions  

Microsoft Academic Search

Ionic magnetic fluids are aqueous colloidal solutions of magnetic nanoparticles which wear surface charges. Stability of the\\u000a solution is ensured by screened electrostatic repulsions, and phase transitions “gas-liquid” like are observed when an electrolyte\\u000a is added to the colloidal solution. The nature and the onset of the transitions are determined as functions of the nature\\u000a of the particles (maghemite or

V. Cabuil; E. Dubois; S. Neveu; J. Bacri; E. Hasmonay; R. Perzynski

38

Analytical methods for separating and isolating magnetic nanoparticles.  

PubMed

Despite the large body of literature describing the synthesis of magnetic nanoparticles, few analytical tools are commonly used for their purification and analysis. Due to their unique physical and chemical properties, magnetic nanoparticles are appealing candidates for biomedical applications and analytical separations. Yet in the absence of methods for assessing and assuring their purity, the ultimate use of magnetic particles and heterostructures is likely to be limited. In this review, we summarize the separation techniques that have been initially used for this purpose. For magnetic nanoparticles, it is the use of an applied magnetic flux or field gradient that enables separations. Flow based techniques are combined with applied magnetic fields to give methods such as magnetic field flow fractionation and high gradient magnetic separation. Additional techniques have been explored for manipulating particles in microfluidic channels and in mesoporous membranes. Further development of these and new analytical tools for separation and analysis of colloidal particles is critically important to enable the practical use of these, particularly for medicinal purposes. PMID:22306911

Stephens, Jason R; Beveridge, Jacob S; Williams, Mary Elizabeth

2012-02-03

39

Magnetic Separation of Soluble Organic Pollutants from Water.  

National Technical Information Service (NTIS)

The potential use of High Gradient Magnetic Separation (HGMS) for removing soluble organics in water and for treating composite wastewater from a food processing unit was studied. The initial investigation was of soluble organic removal by a combined use ...

J. A. Petruska J. V. Perumpral

1977-01-01

40

Cell Separation Using Protein-A-Coated Magnetic Nanoclusters  

Microsoft Academic Search

A new immunomagnetic separation process that uses protein A-coated magnetic nanoclusters (PACMAN) as the separation vehicles has been developed. The nanoclusters are produced by sonicating egg yolk phosphatidylcholine and the transmembrane Fc receptor protein-A in a buffered aqueous ferrofluid suspension. The phospholipids appear to form a coating around clusters of 5-50 magnetic nanoparticles, while some of the protein-A associate with

Srinivas V. Sonti; Arijit Bose

1995-01-01

41

Self-Assembled Magnetic Filter for Highly Efficient Immunomagnetic Separation  

PubMed Central

We have developed a compact and inexpensive microfluidic chip, the Self Assembled Magnetic filter, to efficiently remove magnetically tagged cells from suspension. The self-assembled magnetic filter consists of a microfluidic channel built directly above a self-assembled NdFeB magnet. Micrometer-sized grains of NdFeB assemble to form alternating magnetic dipoles, creating a magnetic field with a very strong magnitude B (from the material) and field gradient ?B (from the configuration) in the microfluidic channel. The magnetic force imparted on magnetic beads is measured to be comparable to state-of-the-art microfabricated magnets, allowing for efficient separations to be performed in a compact, simple device. The efficiency of the magnetic filter is characterized by sorting non-magnetic (polystyrene) beads from magnetic beads (iron oxide). The filter enriches the population of non-magnetic beads to magnetic beads by a factor of >105 with a recovery rate of 90% at 1 mL/hr. The utility of the magnetic filter is demonstrated with a microfluidic device that sorts tumor cells from leukocytes using negative immunomagnetic selection, and concentrates the tumor cells on an integrated membrane filter for optical detection.

Issadore, David; Shao, Huilin; Chung, Jaehoon; Newton, Andita; Pittet, Mikael; Weissleder, Ralph; Lee, Hakho

2010-01-01

42

Magnetically separable nanocatalysts: bridges between homogeneous and heterogeneous catalysis.  

PubMed

Recovery and reuse of expensive catalysts after catalytic reactions are important factors for sustainable process management. The aim of this Review is to highlight the progress in the formation and catalytic applications of magnetic nanoparticles and magnetic nanocomposites. Directed functionalization of the surfaces of nanosized magnetic materials is an elegant way to bridge the gap between heterogeneous and homogeneous catalysis. The introduction of magnetic nanoparticles in a variety of solid matrices allows the combination of well-known procedures for catalyst heterogenization with techniques for magnetic separation. PMID:20419718

Shylesh, Sankaranarayanapillai; Schünemann, Volker; Thiel, Werner R

2010-05-01

43

Separation of actinide-made transurania by a gas-filled magnetic separator  

Microsoft Academic Search

The performance of the gas-filled magnetic separator HECK at the UNILAC at GSI Darmstadt is described. The system consists of a 30°-dipole magnet and a quadrupole doublet of wide aperture. The separator is operated with helium at pressures between 0.1–1 hPa. It is used to investigate heavy ion induced fusion products in-flight. The recoils emerging from a thin target are

V. Ninov; P. Armbruster; F. P. Heßberger; S. Hofmann; G. Münzenberg; Y. Fujita; M. Leino; A. Lüttgen

1995-01-01

44

Performances of a waste recycling separator with permanent magnets  

Microsoft Academic Search

The polarization fixed point method coupled with Green function method is used for computation the magnetic field. Magnetic force is obtained by using Maxwell tensor. The procedure avoids the spurious forces introduced by artificial boundary or by meshing the air zone. As a performance of the separator, the difference between the detachment angle of ferromagnetic and nonferromagnetic bodies is evaluated.

Florea Hantila; Mihai Maricaru; Claudia Popescu; Costin Ifrim; Stergios Ganatsios

2007-01-01

45

Apparatus and method for continuous separation of magnetic particles from non-magnetic fluids  

DOEpatents

A magnetic separator vessel (1) for separating magnetic particles from non-magnetic fluid includes a separation chamber having an interior and exterior wall, a top and bottom portion; a magnet (3) having first and second poles (2) positioned adjacent to the exterior wall, wherein the first pole is substantially diametrically opposed to the second pole; a inlet port (5) is directed into the top portion of the separation chamber, wherein the inlet port (5) is positioned adjacent to one of the first and second poles (2), wherein the inlet port (5) is adapted to transfer a mixture into the separation chamber; an underflow port (6) in communication with the bottom portion, wherein the underflow port (6) is adapted to receive the magnetic particles; and an overflow port (9) in communication with the separation chamber, wherein the overflow port (9) is adapted to receive the non-magnetic fluid.

Oder, Robin R. (Export, PA); Jamison, Russell E. (Lower Burrell, PA)

2010-02-09

46

Separation and acceleration of magnetic monopole analogs in semiconductor microcavities  

NASA Astrophysics Data System (ADS)

Half-integer topological defects in polariton condensates can be regarded as magnetic charges, with respect to built-in effective magnetic fields present in microcavities. We show how an integer topological defect can be separated into a pair of half-integer ones, paving the way for flows of magnetic charges: spin currents or magnetricity. We discuss the corresponding experimental implementation within microwires (with half-solitons) and planar microcavities (with half-vortices).

Flayac, H.; Solnyshkov, D. D.; Malpuech, G.

2012-08-01

47

Hydrophobic partitioning approach to efficient protein separation with magnetic nanoparticles  

Microsoft Academic Search

A novel approach to the hydrophobic partitioning effect on efficient separation of protein such as BSA was demonstrated by the modification of hydrophobic pockets on the surface of silica-coated magnetic nanoparticles with various alkyl groups at various pH levels. The separation efficiency is strongly reflected and can be attained by controlling the size of the hydrophobic pocket and other factors

Jeong Ho Chang; Jiho Lee; Yeonhwan Jeong; Jin Hyung Lee; Ik Jin Kim; Sang Eon Park

2010-01-01

48

Using magnetic levitation to separate mixtures of crystal polymorphs.  

PubMed

Magnetic levitation (MagLev) provides a simple method for the separation of crystal polymorphs that differ in density (??) by greater than 0.001?g?cm(-3) . Density-based separations of multiple crystalline forms were shown for four organic compounds: 5-methyl-2-[(2-nitro- phenyl)amino]-3-thiophenecarbonitrile, sulfathiazole, carbamazepine, and trans- cinnamic acid. PMID:23939940

Atkinson, Manza B J; Bwambok, David K; Chen, Jie; Chopade, Prashant D; Thuo, Martin M; Mace, Charles R; Mirica, Katherine A; Kumar, Ashok A; Myerson, Allan S; Whitesides, George M

2013-08-12

49

Separation of Fullerence Molecules in an Eletric-Magnetic Isotope Separator  

Microsoft Academic Search

An electric-magnetic isotope separator was used to separate fullerence molecules C60 and C70 produced by dc contact arc vaporization then extracting method. The potential for the analysis of huge fullerence molecules and the producing of macroscopic quantity of any fullerence molecules was revealed. It also showed that the secondly ionized molecules might be produced in the sample preparing process. Bibtex

Fucheng Lin; Zhengliang Wu; Yanyan Xie; Guilin Zhang; Miao Chen; Yingji Zhang

1993-01-01

50

Microfabricated magnetic sifter for high-throughput and high-gradient magnetic separation  

PubMed Central

A microfabricated magnetic sifter has been designed and fabricated for applications in biological sample preparation. The device enables high-throughput, high-gradient magnetic separation of magnetic nanoparticles by utilizing columnar fluid flow through a dense array (~5000/mm2) of micropatterned slots in a magnetically soft membrane. The potential of the sifter for separation of magnetic nanoparticles conjugated with capture antibodies is demonstrated through quantitative separation experiments with CD138-labelled MACS nanoparticles. Capture efficiencies ranging from 28–37% and elution efficiencies greater than 73% were measured for a single pass through the sifter.

Earhart, Christopher M.; Wilson, Robert J.; White, Robert L.; Pourmand, Nader; Wang, Shan X.

2009-01-01

51

Use of high gradient magnetic separation for actinide application  

SciTech Connect

Decontamination of materials such as soils or waste water that contain radioactive isotopes, heavy metals, or hazardous components is a subject of great interest. Magnetic separation is a physical separation process that segregates materials on the basis of magnetic susceptibility. Because the process relies on physical properties, separations can be achieved while producing a minimum of secondary waste. Most traditional physical separation processes effectively treat particles larger than 70 microns. In many situations, the radioactive contaminants are found concentrated in the fine particle size fraction of less than 20 microns. For effective decontamination of the fine particle size fraction most current operations resort to chemical dissolution methods for treatment. High gradient magnetic separation (HGMS) is able to effectively treat particles from 90 to {approximately}0.1 micron in diameter. The technology is currently used on the 60 ton per hour scale in the kaolin clay industry. When the field gradient is of sufficiently high intensity, paramagnetic particles can be physically captured and separated from extraneous nonmagnetic material. Because all actinide compounds are paramagnetic, magnetic separation of actinide containing mixtures is feasible. The advent of reliable superconducting magnets also makes magnetic separation of weakly paramagnetic species attractive. HGMS work at Los Alamos National Laboratory (LANL) is being developed for soil remediation, waste water treatment and treatment of actinide chemical processing residues. LANL and Lockheed Environmental Systems and Technologies Company (LESAT) have worked on a co-operative research and development agreement (CRADA) to develop HGMS for radioactive soil decontamination. The program is designed to transfer HGMS from the laboratory and other industries for the commercial treatment of radioactive contaminated materials. 9 refs., 2 figs., 2 tabs.

Avens, L.R.; Worl, L.A.; Padilla, D.D.

1996-08-01

52

Application of high temperature superconductors to high-gradient magnetic separation  

Microsoft Academic Search

High Gradient Magnetic Separation (HGMS) is a powerful technique which can be used to separate widely dispersed contaminants from a host material, This technology can separate magnetic solids from other solids, liquids, or gases. As the name implies, HGMS uses large magnetic field gradients to separate ferromagnetic and paramagnetic particles. HGMS separators usually consist of a high-field solenoid magnet, the

M. A. Daugherty; F. C. Prenger; D. D. Hill; D. E. Daney; L. W. Worl; A. R. Schake; D. D. Padilla

1994-01-01

53

Magnetic microstructures of phase-separated Sm–Co 2:17-type sintered magnets  

Microsoft Academic Search

Magnetic microstructures of high-temperature Sm–Co 2:17-type sintered magnets during phase separation process have been investigated by using magnetic force microscopy. Results show that the magnetic microstructures of final Sm–Co 2:17-type magnets is an aggregation of many single domains. The evolution of domain structures was explained on the basis of variation of phase constitutions of the specimens together with crystalline microstructures

Y. K. Fang; H. W. Chang; Z. H. Guo; T. Liu; X. M. Li; W. Li; W. C. Chang; B. S. Han

2008-01-01

54

CryoSeal FS System  

Center for Biologics Evaluation and Research (CBER)

... Applicant: ThermoGenesis Corp Product: CryoSeal FS System PMA number: BP060001 ... of autologous human plasma only in a closed, sterile fluid ... More results from www.fda.gov/biologicsbloodvaccines/bloodbloodproducts/approvedproducts

55

Waste remediation using in situ magnetically assisted chemical separation  

SciTech Connect

The magnetically assisted chemical separation process (MACS) combines the selective and efficient separation afforded by chemical sorption with the magnetic recovery of ferromagnetic particles. This process is being developed for treating the underground storage tanks at Hanford. These waste streams contain cesium, strontium, and transuranics (TRU) that must be removed before this waste can be disposed of as grout. The separation process uses magnetic particles coated with either (1) a selective ion exchange material or an organic extractant containing solvent (for cesium and strontium removal) or (2) solvents for selective separation of TRU elements (e.g., TRUEX process). These coatings, by their chemical nature, selectively separate the contaminants onto the particles, which can then be recovered from the tank using a magnet. Once the particles are removed, the contaminants can either be left on the loaded particles and added to the glass feed slurry or stripped into a small volume of solution so that the extracting particles can be reused. The status of chemistry and separation process is discussed in this paper.

Nunez, L.; Buchholz, B.A.; Vandegrift, G.F.

1993-11-01

56

Living Planet: CryoSat  

NSDL National Science Digital Library

This is an overview of the CryoSat program, a three-year radar altimetry mission by the European Space Agency (ESA), scheduled for launch in September 2005. The mission will measure variations in the thickness of the Earth's continental ice sheets and marine ice cover in an effort to determine whether arctic ice is thinning due to global warming. Topics include an introduction to the mission, news articles, science objectives, data products, and links to CryoSat publications.

57

Development of the superconducting magnet system for industrial high gradient magnetic separator  

SciTech Connect

This paper reports that to promote the effective development of superconducting magnetic separation technology and its practical industrial application for Kaolin clay beneficiation, the Institute of Electrical Engineering and the Cryogenic Laboratory, Academia Sinica are jointly working on the development of an industrial prototype superconducting magnetic separator.

Yan, L.; Yi, C.; Yu, Y. (Inst. of Electrical Engineering, Academia Sinica, P.O. Box 2703, Beijing 100080 (CN)); Cai, G.; Tu, G. (Cryogenic Lab., Academia Sinica, P.O. Box 2711, Beijing 100080 (CN))

1991-03-01

58

Study on industrial wastewater treatment using superconducting magnetic separation  

Microsoft Academic Search

The mechanism of industrial wastewater treatment using superconducting magnetic separation is investigated. Fe3O4 nanoparticles were prepared by liquid precipitation and characterized by X-ray diffraction (XRD). Polyacrylic acid (PAA) film was coated on the magnetic particles using plasma coating technique. Transmission electron microscope (TEM) observation and infrared spectrum measurement indicate that the particle surface is well coated with PAA, and the

Hao Zhang; Zhengquan Zhao; Xiangdong Xu; Laifeng Li

2011-01-01

59

Silica coated magnetic nanoparticles for separation of nuclear acidic waste  

SciTech Connect

Fe{sub 2}O{sub 3} magnetic nanoparticles (MNPs) have been coated with silica, followed by covalent attachment of the actinide specific chelators to separate nuclear waste in acidic conditions. A general model is developed to relate the surface coating to the particle's magnetization change, providing an alternative way to characterize the size-distribution/aggregation of MNPs. The optimized silica coating protects the Fe{sub 2}O{sub 3} MNPs from iron leaching under highly acidic conditions, facilitates the dispersion of MNPs, and dramatically increases the loading capacity of chelator onto the MNPs. Compared with the uncoated counterparts, the silica coated MNPs show enhanced actinide separation efficiency.

Han, H.; Kaur, M.; Qiang, Y. [Department of Physics and Environmental Science, University of Idaho, Moscow, Idaho 83844 (United States); Johnson, A.; Paszczynski, A. [Environmental Biotechnology Institute, Molecular Biology and Biochemistry, University of Idaho, Moscow, Idaho 83844 (United States); Department of Microbiology, Molecular Biology and Biochemistry, University of Idaho, Moscow, Idaho 83844 (United States); Kaczor, J. [Environmental Biotechnology Institute, Molecular Biology and Biochemistry, University of Idaho, Moscow, Idaho 83844 (United States)

2010-05-15

60

The study on optimization issues for magnetic separation by magnetic chromatography  

NASA Astrophysics Data System (ADS)

The magnetic chromatography is a very useful system for an ion and/or fine magnetic particle separation because it has strong magnetic field gradients even in a very narrow flow channel. We have not only developed the magnetic chromatography system to separate the fine particles and ions, but also the numerical analysis code based on the fluid dynamics and electromagnetism to investigate the separating characteristics and to optimize design of magnetic column. In this study, the simple experiments using a superconducting magnet with a large room-temperature-bore and a micro-scale magnetic column consisting of ferromagnetic wires were carried out to understand the ions separation. The cobalt chloride (CoCl2) and the nickel sulfate (NiSO4) were used as ions, and the magnetic field and length of magnetic column were used as a parameter in an experiment and an analysis. It can be expected that the ion mobility of a single and complex are quite different, and the ability of the separation will be improved by increasing the column length without external magnetic field.

Kim, S. B.; Iwamoto, R.; Kataoka, K.; Noguchi, S.; Okada, H.

2010-11-01

61

Photocatalytic magnetic separable beads for chromium (VI) reduction.  

PubMed

Magnetically separable photocatalyst beads containing nano-sized iron oxide in alginate polymer were prepared. This magnetic photocatalyst beads are used in slurry-type reactors. The magnetism of the catalyst arises from the nanostructured particles gamma-Fe(2)O(3), by which the catalyst can be easily recovered by the application of an external magnetic field. These synthesized beads are sunlight-driven photocatalyst. In the system without magnetic photocatalyst beads, no chromium reduction was observed under sunlight irradiation due to the stability of the chromium (VI). Upon the addition of magnetic photocatalyst beads, the photo-reduction of Cr(VI) was completed in just after only 50min under sunlight irradiation due to the photocatalytic activity of the beads. However when placed away from sunlight, the reduction rate of the chromium is just about 10%. These observations were explained in terms of absorption occurrence of chromium (VI) onto the catalyst surface which took place in this reaction. In addition, photo-reduction rate of chromium (VI) was more significant at lower pH. The results suggest that the use of magnetic separable photocatalyst beads is a feasible strategy for eliminating Cr(VI). PMID:19963234

Idris, Ani; Hassan, Nursia; Mohd Ismail, Nur Suriani; Misran, Effaliza; Yusof, Noordin Mohd; Ngomsik, Audrey-Flore; Bee, Agnes

2009-11-26

62

TREATMENT OF COMBINED SEWER OVERFLOWS BY HIGH GRADIENT MAGNETIC SEPARATION  

EPA Science Inventory

Seeded water treatment by high gradient magnetic separation techniques was carried out on combined storm overflows and raw sewage influents. Both bench-type and continuous pilot plant tests were performed to evaluate the effectiveness of the process in purifying waste waters. Cri...

63

Magnetic separation as a plutonium residue enrichment process  

SciTech Connect

We have subjected several plutonium contaminated residues to Open Gradient Magnetic Separation (OGMS) on an experimental scale. Separation of graphite, bomb reduction sand, and bomb reduction sand, and bomb reduction sand, slag, and crucible, resulted in a plutonium rich fraction and a plutonium lean fraction. The lean fraction varied between about 20% to 85% of the feed bulk. The plutonium content of the lean fraction can be reduced from about 2% in the feed to the 0.1% to 0.5% range dependent on the portion of the feed rejected to this lean fraction. These values are low enough in plutonium to meet economic discard limits and be considered for direct discard. Magnetic separation of direct oxide reduction and electrorefining pyrochemical salts gave less favorable results. While a fraction very rich in plutonium could be obtained, the plutonium content of the lean fraction was to high for direct discard. This may still have chemical processing applications. OGMS experiments at low magnetic field strength on incinerator ash did give two fractions but the plutonium content of each fraction was essentially identical. Thus, no chemical processing advantage was identified for magnetic separation of this residue. The detailed results of these experiments and the implications for OGMS use in recycle plutonium processing are discussed. 4 refs., 3 figs., 9 tabs.

Avens, L.R.; McFarlan, J.T.; Gallegos, U.F.

1989-01-01

64

Magnetic Separations with Magnetite: Theory, Operation, and Limitations  

SciTech Connect

This dissertation documents the theory development and experimental plan followed to describe how a magnetite-based column under the influence of an external magnetic field functions as a magnetic separator. Theoretical simulations predict that weekly paramagnetic particles in the sub-micron range can be magnetically separated while diamagnetic particles as large as 2 microns in diameter may pass. Magnetite-based columns were evaluated as magnetically-controllable enhanced filtration devices. There was no evidence of enhanced filtration for diamagnetic particles by the magnetite-based bed. Magnetite-based magnetic separators have proven to be effective in specific laboratory experiments, indicating a potential feasibility for scale-up operations. Column media-filter type filtration effects indicate a magnetite-based column would not be suitable for treatment of a waste stream with a high diamagnetic solids content or high volume throughput requirements. Specific applications requiring removal of sub-micron para- or ferromagnetic particles under batch or Stokes flow conditions would be most applicable.

G. B. Cotten

2000-08-01

65

Magnetic precipitate separation for Ni plating waste liquid using HTS bulk magnets  

NASA Astrophysics Data System (ADS)

The magnetic separation experiment for recycling the nickel-bearing precipitates in the waste liquid from the electroless plating processes has been practically conducted under the high gradient magnetic separation technique with use of the face-to-face HTS bulk magnet system. A couple of facing magnetic poles containing Sm123 bulk superconductors were activated through the pulsed field magnetization process to 1.86 T at 38 K and 2.00 T at 37 K, respectively. The weakly magnetized metallic precipitates of Ni crystals and Ni-P compounds deposited from the waste solution after heating it and pH controlling. The high gradient magnetic separation technique was employed with the separation channels filled with the stainless steel balls with dimension of 1 and 3 mm in diameter, which periodically moved between and out of the facing magnetic poles. The Ni-bearing precipitates were effectively attracted to the magnetized ferromagnetic balls. We have succeeded in obtaining the separation ratios over 90% under the flow rates less than 1.35 L/min.

Oka, T.; Kimura, T.; Mimura, D.; Fukazawa, H.; Fukui, S.; Ogawa, J.; Sato, T.; Ooizumi, M.; Yokoyama, K.; Tsujimura, M.; Terasawa, T.

2013-01-01

66

Tank waste remediation system milestone report magnetic separation of tank waste: Surrogate system separations report  

SciTech Connect

High-level radioactive waste (HLW) has been stored in large underground storage tanks (UST) at the US Department of Energy`s Hanford Site since 1944. More than 253,000 m{sup 3} of waste have been accumulated in 177 tanks. The waste consists of many different chemicals and are in the form of liquids, slurries, salt cakes and sludges. A magnetic separation effort at Los Alamos National Laboratory is funded through the Tank Waste Remediation System (TWRS) to explore the use of high-gradient magnetic separation (HGMS) for tank waste segregation. The concept is to concentrate into a low volume waste stream, all or most of the magnetic components, which include actinide compounds, most of the fission products and precious metals. As a first step in this process investigations were made on surrogate systems. This milestone report discusses the HGMS results on these systems.

Avens, L.R.; Worl, L.A.; Schake, A.R.; Padilla, D.D.; de Aguero, K.J.; Prenger, F.C.; Stewart, W.F.; Hill, D.D.

1994-01-14

67

Magnetic design considerations for devices and particles used for biological high-gradient magnetic separation (HGMS) systems  

Microsoft Academic Search

An overview of the magnetic systems used in biological high-gradient magnetic separation (HGMS) is presented. The magnetic design parameters of a range of separation devices are discussed. Such designs have distinct magnetic field characteristics and are usually tailored to meet the needs of particular protocols. The various types of magnets and particles are also discussed, with a comparison of materials

Gareth P. Hatch; Richard E. Stelter

2001-01-01

68

Endotoxin removal by magnetic separation-based blood purification.  

PubMed

This work describes a magnetic separation-based approach using polymyxin B-functionalized metal alloy nanomagnets for the rapid elimination of endotoxins from human blood in vitro and functional assays to evaluate the biological relevance of the blood purification process. Playing a central role in gram-negative sepsis, bacteria-derived endotoxins are attractive therapeutic targets. However, both direct endotoxin detection in and removal from protein-rich fluids remains challenging. We present the synthesis and functionalization of ultra-magnetic cobalt/iron alloy nanoparticles and a magnetic separation-based approach using polymyxin B-functionalized nanomagnets to remove endotoxin from human blood in vitro. Conventional chromogenic Limulus Amebocyte Lysate assays confirm decreased endotoxin activity in purified compared to untreated samples. Functional assays assessing key steps in host defense against bacteria show an attenuated inflammatory mediator expression from human primary endothelial cells in response to purified blood samples compared to untreated blood and less chemotactic activity. Exposing Escherichia coli-positive blood samples to polymyxin B-functionalized nanomagnets even impairs the ability of gram-negative bacteria to form colony forming units, thus making magnetic separation based blood purification a promising new approach for future sepsis treatment. PMID:23225582

Herrmann, Inge K; Urner, Martin; Graf, Samuel; Schumacher, Christoph M; Roth-Z'graggen, Birgit; Hasler, Melanie; Stark, Wendelin J; Beck-Schimmer, Beatrice

2012-12-06

69

Separation of impurity in molten metals by using superconducting magnet  

NASA Astrophysics Data System (ADS)

The separation method by using electromagnetic force is receiving particular attention as elimination method of impurities in molten metal. In this study, low-melting metal is used as model metal and the relation between electromagnetic force and motion of the particle in molten metal was discussed by calculation and experiment. As the result of calculation, the relation between electromagnetic force and separation efficiency can be obtained. The electromagnetic separation was experimented in the condition that was estimated from the results of calculation (average flow velocity: 0.4 m/s, magnetic flux density: 10 T, electric current density: 3.3E+4 A/m2). It succeeded that insulating lead balls in low-melting metal were separated by electromagnetic force.

Terada, T.; Akiyama, Y.; Izumi, Y.; Nishijima, S.

2009-10-01

70

Ramp rate testing of an HTS high gradient magnetic separation magnet  

SciTech Connect

The authors report on the ramp rate testing of a prototype high temperature superconducting (HTS) high gradient magnetic separation (HGMS) magnet. HGMS magnets are ramped from full field to zero field to clean the separation matrix. The time spent ramping the magnet is unavailable for processing and must therefore be kept to a minimum. Existing commercial low temperature superconducting HGMS magnets are immersed in a liquid helium bath and are designed to ramp from zero to full current in one minute. The HTS magnet in the system is conductively cooled and operates in a vacuum at a temperature of approximately 30 K. Heat generated during ramping is not as readily removed from the conductively cooled magnet as a bath cooled magnet. To verify that the conductive cooling can adequately remove heat generated during ramping they recorded magnet temperatures and voltages while ramping at rates of up to 4.8 A/second. The magnet can accommodate ramps from zero to 100 A (1.6 Tesla) in 21 seconds with no degradation in performance. The average magnet temperature rises a maximum of 1 K during ramping. Using temperatures recorded during ramps they have made rough estimates of the ac losses generated in the magnet.

Daugherty, M.A.; Roth, E.W.; Daney, D.E.; Hill, D.D.; Prenger, F.C.

1997-11-01

71

Oil-field wastewater purification by magnetic separation technique using a novel magnetic nanoparticle  

NASA Astrophysics Data System (ADS)

In the present work, oil-field wastewater purification through superconducting magnetic separation technique using a novel magnetic nanoparticle was investigated. The magnetic nanoparticle, which has a multi-shell structure with ferroferric oxide as core, dense nonporous silica as inter layer and mesoporous silica as outer layer, was synthesized by co-precipitation method. To functionalize the magnetic nanoparticle, plasma polymerization technique was adopted and poly methyl acrylate (PMA) was formed on the surface of the nanoparticle. The multi-shell structure of the nanoparticle was confirmed by transmission electron microscope (TEM) and the characteristic is measurable by FTIR. It is found that most of the pollutants (85% by turbidity or 84% by COD value) in the oil-field wastewater are removed through the superconducting magnetic separation technique using this novel magnetic nanoparticle.

Liu, Zhuonan; Yang, Huihui; Zhang, Hao; Huang, Chuanjun; Li, Laifeng

2012-12-01

72

Feasibility study of iron mineral separation from red mud by high gradient superconducting magnetic separation  

NASA Astrophysics Data System (ADS)

The disposal of bayer red mud tailings now seriously threats the environment safety. Reduction and recycling of red mud is now an urgent work in aluminum industry. High gradient superconducting magnetic separation (HGSMS) system was applied to separate the extreme fine RM particles (<100 ?m) into high iron content part and low iron content part. Two sorts of RM were fed in the HGSMS. The iron oxide contents in concentrates were about 65% and 45% when RM 1# and RM 2# were fed respectively. Meanwhile, the residues contained 52.0% or 14.1% iron oxide in residues after eight separation stages when RM 1# and RM 2# were fed respectively. The mass recovery of iron concentrates was about 10% after once separation process regardless of RM 1# or RM 2# was fed. Extreme fine particles (<10 ?m) could be captured in the HGSMS. Intergrowth of Fe and other elements is disadvantages for iron mineral separation from RM by HGSMS. Some improvement should be studied to enhance the efficiency of iron separation. It is possible for HGSMS to separate RM into high iron content part and low iron content part, the former part could be used in iron-making furnace and the later part could be recycling to sintering process for alumina production or used as construction material.

Li, Yiran; Wang, Jun; Wang, Xiaojun; Wang, Baoqiang; Luan, Zhaokun

2011-02-01

73

Magnetic Separation for Nuclear Material Detection and Surveillance  

SciTech Connect

A high performance superconducting magnet is being developed for particle retrieval from field collected samples. Results show that maximum separation effectiveness is obtained when the matrix fiber diameter approaches the diameter of the particles to be captured. Experimentally, the authors obtained a single particle capture limit with 0.8{micro}m PuO{sub 2} particles with dodecane as a carrier fluid. The development of new matrix materials is being pursued through the controlled corrosion of stainless steel wool, or the deposition of nickel dendrites on the existing stainless steel matrix material. They have also derived a model from a continuity equation that uses empirically determined capture cross section values. This enables the prediction of high gradient magnetic separator performance for a variety of materials and applications. The model can be used to optimize the capture cross section and thus increase the capture efficiency.

Worl, L.A.; Devlin, D.; Hill, D.; Padilla, D.; Prenger, F.C.

1998-08-01

74

Capture of metallic copper by high gradient magnetic separation system  

Microsoft Academic Search

Valence copper was recovered from wastewater by chemical reduction and use of a high gradient magnetic separation (HGMS) system. Ammonia (NH3) and sodium dithionate (Na2S2O4) at a molar ratio of [Cu]:[NH3]:[Na2S2O4] = 1:4:3 at pH = 9.5 were used first to chemically reduce copper ion to metallic copper; the resultant metal solids were captured in an upflowing reactor space equipped

P. K. Andy Hong

2011-01-01

75

Tank waste remediation system milestone report magnetic separation of tank waste: Surrogate system separations report  

Microsoft Academic Search

High-level radioactive waste (HLW) has been stored in large underground storage tanks (UST) at the US Department of Energy`s Hanford Site since 1944. More than 253,000 m³ of waste have been accumulated in 177 tanks. The waste consists of many different chemicals and are in the form of liquids, slurries, salt cakes and sludges. A magnetic separation effort at Los

L. R. Avens; L. A. Worl; A. R. Schake; D. D. Padilla; K. J. de Aguero; F. C. Prenger; W. F. Stewart; D. D. Hill

1994-01-01

76

Cryo Utilities Room Cooling System  

Microsoft Academic Search

Many of the mechanical equipment failures at the Laboratory are due to the loss of cooling water. In order to insure the proper operating temperatures and to increase the reliability of the mechanical equipment in the D0 Cryo Utilities Room it is necessary to provide an independent liquid cooling system. To this end, an enclosed glycoVwater cooling system which transfers

G. S. Ball

1989-01-01

77

Radiolysis and hydrolysis of magnetically assisted chemical separation particles  

SciTech Connect

The magnetically assisted chemical separation (MACS) process is designed to separate transuranic (TRU) elements out of high-level waste (HLW) or TRU waste. Magnetic microparticles (1--25 {mu}m) were coated with octyl (phenyl)N,N-diisobutylcarbamoylmethylphosphine oxide (CMPO) dissolved in tributyl phosphate (TBP) and tested for removing TRU elements from acidic nitrate solutions. The particles were contacted with nitric acid solutions and Hanford plutonium finishing plant (PFP) simulant, irradiated with a high intensity {sup 60}Co {gamma}-ray source, and evaluated for effectiveness in removing TRU elements from 2m HNO{sub 3} solutions. The resistance of the coatings and magnetic cores to radiolytic damage and hydrolytic degradation was investigated by irradiating samples of particles suspended in a variety of solutions with doses of up to 5 Mrad. Transmission electron microscopy (TEM), magnetic susceptibility measurements, and physical observations of the particles and suspension solutions were used to assess physical changes to the particles. Processes that affect the surface of the particles dramatically alter the binding sites for TRU in solution. Hydrolysis played a larger role than radiolysis in the degradation of the extraction capacity of the particles.

Buchholz, B.A.; Nunez, L.; Vandegrift, G.F.

1995-05-01

78

Plasma separation process: Magnet move to Oak Ridge National Laboratory  

SciTech Connect

This is the final report on the series of operations which culminated with the delivery of the Plasma Separation Process prototype magnet system (PMS) to Building K1432 at Oak Ridge National Laboratory (ORNL). This procedure included real time monitoring of the cold mass support strut strain gauges and an in-cab rider to monitor the instrumentation and direct the driver. The primary technical consideration for these precautions was the possibility of low frequency resonant vibration of the cold mass when excited by symmetrical rough road conditions at specific speeds causing excess stress levels in the support struts and consequent strut failure. A secondary consideration was the possibility of high acceleration loads due to sudden stops, severe road conditions, of impacts. The procedure for moving and transportation to ORNL included requirements for real time continuous monitoring of the eight strut stain gauges and three external accelerometers. Because the strain gauges had not been used since the original magnet cooldown, it was planned to verify their integrity during magnet warmup. The measurements made from the strut strain gauges resulted in stress values that were physically impossible. It was concluded that further evaluation was necessary to verify the usefulness of these gauges and whether they might be faulty. This was accomplished during the removal of the magnet from the building. 6 figs., 1 tab.

Not Available

1989-07-01

79

Apparatus for magnetic separation of paramagnetic and diamagnetic material  

DOEpatents

The present invention relates to methods and apparatus for segregating paramagnetic from diamagnetic particles in particulate material and, in particular, to the open gradient magnetic separation of ash producing components and pyritic sulfur from coal. The apparatus includes a vertical cylinder and a rotatable vertical screw positioned within the cylinder, the screw having a helical blade angled downwardly and outwardly from the axis. Rotation of the vertical screw causes denser particles, which in the case of coal include pyritic sulfur and ash, which are paramagnetic, to migrate to the outside of the screw, and less dense particles, such as the low sulfur organic portion of the coal, which are diamagnetic, to migrate towards the center of the screw. A vibration mechanism attached to the screw causes the screw to vibrate during rotation, agitating and thereby accommodating further segregation of the particles. An open gradient magnetic field is applied circumferentially along the entire length of the screw by a superconducting quadrupole magnet. The open gradient magnetic field further segregates the paramagnetic particles from the diamagnetic particles. The paramagnetic particles may then be directed from the cylinder into a first storage bin, and the diamagnetic particles, which are suitable for relatively clean combustion, may be directed into a second storage bin. 5 figs.

Doctor, R.D.

1988-10-18

80

Charge separation of plasma flow in curvilinear magnetic field  

NASA Astrophysics Data System (ADS)

The energy spectra of ions occurring in various charged states in a flow of titanium plasma in a steady-state vacuum arc discharge have been studied. It is established that, during the motion of this flow through a plasma transport system based on a curvilinear magnetic field, ions with different charges are spatially separated. As a result, at the system output, ions with greater charges are concentrated in the inner part of the plasma flow, so that the average charge of ions in this region is higher than that in the outer part of the flow.

Korobkin, Yu. V.; Lebedev, N. V.; Paperny, V. L.

2012-03-01

81

Detection of carcinoembryonic antigen using functional magnetic and fluorescent nanoparticles in magnetic separators  

Microsoft Academic Search

We combined a sandwich immunoassay, anti-CEA\\/CEA\\/anti-CEA, with functional magnetic (~80 nm) and fluorescent (~180 nm) nanoparticles\\u000a in magnetic separators to demonstrate a detection method for carcinoembryonic antigen (CEA). Determination of CEA in serum\\u000a can be used in clinical diagnosis and monitoring of tumor-related diseases. The CEA concentrations in samples were deduced\\u000a and determined based on the reference plot using the measured fluorescent

H. Y. Tsai; C. Y. Chang; Y. C. Li; W. C. Chu; K. Viswanathan; C. Bor Fuh

2011-01-01

82

3.88Astructure of cytoplasmic polyhedrosis virus by cryo-electron microscopy  

Microsoft Academic Search

we report the three-dimensional structure of CPV at 3.88 A û reso- lution using single-particle cryo-electron microscopy. Our map clearly shows the turns and deep grooves of a-helices, the strand separation inb-sheets, and densities for loops and many bulky side chains; thus permitting atomic model-building effort from cryo- electron microscopy maps. We observed a helix-to-b-hairpin conformational change between the two

Xuekui Yu; Lei Jin; Z. Hong Zhou

83

On-chip Magnetic Separation and Cell Encapsulation in Droplets  

NASA Astrophysics Data System (ADS)

The demand for high-throughput single cell assays is gaining importance because of the heterogeneity of many cell suspensions, even after significant initial sorting. These suspensions may display cell-to-cell variability at the gene expression level that could impact single cell functional genomics, cancer, stem-cell research and drug screening. The on-chip monitoring of individual cells in an isolated environment could prevent cross-contamination, provide high recovery yield and ability to study biological traits at a single cell level These advantages of on-chip biological experiments contrast to conventional methods, which require bulk samples that provide only averaged information on cell metabolism. We report on a device that integrates microfluidic technology with a magnetic tweezers array to combine the functionality of separation and encapsulation of objects such as immunomagnetically labeled cells or magnetic beads into pico-liter droplets on the same chip. The ability to control the separation throughput that is independent of the hydrodynamic droplet generation rate allows the encapsulation efficiency to be optimized. The device can potentially be integrated with on-chip labeling and/or bio-detection to become a powerful single-cell analysis device.

Chen, A.; Byvank, T.; Bharde, A.; Miller, B. L.; Chalmers, J. J.; Sooryakumar, R.; Chang, W.-J.; Bashir, R.

2012-02-01

84

Plasma separation process: Magnet move to Oak Ridge National Laboratory  

NASA Astrophysics Data System (ADS)

This is the final report on the series of operations which culminated with the delivery of the Plasma Separation Process prototype magnet system (PMS) to Building K1432 at Oak Ridge National Laboratory (ORNL). This procedure included real time monitoring of the cold mass support strut strain gauges and an in-cab rider to monitor the instrumentation and direct the driver. The primary technical consideration for these precautions was the possibility of low frequency resonant vibration of the cold mass when excited by symmetrical rough road conditions at specific speeds causing excess stress levels in the support struts and consequent strut failure. A secondary consideration was the possibility of high acceleration loads due to sudden stops, severe road conditions, of impacts. The procedure for moving and transportation to ORNL included requirements for real time continuous monitoring of the eight strut stain gauges and three external accelerometers. Because the strain gauges had not been used since the original magnet cooldown, it was planned to verify their integrity during magnet warmup. The measurements made from the strut strain gauges resulted in stress values that were physically impossible. It was concluded that further evaluation was necessary to verify the usefulness of these gauges and whether they might be faulty.

1989-07-01

85

Magnetic and fluorescence-encoded polystyrene microparticles for cell separation  

NASA Astrophysics Data System (ADS)

Materials assisting with the efforts of cell isolation are attractive for numerous biomedical applications including tissue engineering and cell therapy. Here, we have developed surface modification methods on microparticles for the purposes of advanced cell separation. Iron oxide nanoparticles were incorporated into 200 ?m polystyrene microparticles for separation of particle-bound cells from non-bound cells in suspension by means of a permanent magnet. The polystyrene microparticles were further encoded with fluorescent quantum dots (QD) as identification tags to distinguish between specific microparticles in a mixture. Cluster of differentiation (CD) antibodies were displayed on the surface of the microparticles through direct adsorption and various methods of covalent attachment. In addition, a protein A coating was used to orientate the antibodies on the microparticle surface and to maximise accessibility of the antigen-binding sites. Microparticles which carried CD antibodies via covalent attachment showed greater cell attachment over those modifications that were only adsorbed to the surface through weak electrostatic interactions. Greatest extent of cell attachment was observed on microparticles modified with protein A - CD antibody conjugates. B and T lymphocytes were successfully isolated from a mixed population using two types of microparticles displaying B and T cell specific CD antibodies, respectively. Our approach will find application in preparative cell separation from tissue isolates and for microcarrier-based cell expansion.

Bradbury, Diana; Anglin, Emily J.; Bailey, Sheree; Macardle, Peter J.; Fenech, Michael; Thissen, Helmut; Voelcker, Nicolas H.

2008-12-01

86

Application of high gradient magnetic separation principles to magnetic drug targeting  

NASA Astrophysics Data System (ADS)

A hypothetical magnetic drug targeting system, utilizing high gradient magnetic separation (HGMS) principles, was studied theoretically using FEMLAB simulations. This new approach uses a ferromagnetic wire placed at a bifurcation point inside a blood vessel and an externally applied magnetic field, to magnetically guide magnetic drug carrier particles (MDCP) through the circulatory system and then to magnetically retain them at a target site. Wire collection (CE) and diversion (DE) efficiencies were defined and used to evaluate the system performance. CE and DE both increase as the strength of the applied magnetic field (0.3-2.0T), the amount of ferromagnetic material (iron) in the MDCP (20-100%) and the size of the MDCP (1-10?m radius) increase, and as the average inlet velocity (0.1-0.8ms-1), the size of the wire (50-250?m radius) and the ratio (4-10) of the parent vessel radius (0.25-1.25mm radius) to wire radius decrease. The effect of the applied magnetic field direction (0° and 90°) on CE and DE was minimal. Under these plausible conditions, CEs as high as 70% were obtained, with DEs reaching only 30%; however, when the MDCPs were allowed to agglomerate (4-10?m radius), CEs and DEs of 100% were indeed achieved. These results reveal that this new magnetic drug targeting approach for magnetically collecting MDCPs at a target site, even in arteries with very high velocities, is feasible and very promising; this new approach for magnetically guiding MDCPs through the circulatory system is also feasible but more limited. Overall, this study shows that magnetic drug targeting, based on HGMS principles, has considerable promise as an effective drug targeting tool with many potential applications.

Ritter, James A.; Ebner, Armin D.; Daniel, Karen D.; Stewart, Krystle L.

2004-09-01

87

Fundamental study on magnetic separation of aquatic organisms for preservation of marine ecosystem  

NASA Astrophysics Data System (ADS)

Recently, destruction and disturbance of marine ecosystem have been caused by changes in global environment and transplants of farmed fishes and shellfishes. To solve the problems, water treatment techniques to kill or to remove aquatic organisms are necessary. In this study, application of magnetic separation for removal of the aquatic organisms was examined in order to establish the process with high-speed, compact device and low environmental load. Techniques of magnetic seeding and magnetic separation using superconducting magnet are important for high-speed processing of aquatic organisms. Magnetic seeding is to adhere separating object to the surface of ferromagnetic particles, and magnetic separation is to remove aquatic organisms with magnetic force. First, we confirmed the possibility of magnetic seeding of aquatic organisms, and then interaction between aquatic organisms and ferromagnetic particles was examined. Next, for practical application of magnetic separation system using superconducting magnet for removal of aquatic organisms, particle trajectories were simulated and magnetic separation experiment using superconducting magnet was performed in order to design magnetic separation system to achieve high separation efficiency.

Sakaguchi, F.; Akiyama, Y.; Izumi, Y.; Nishijima, S.

2009-10-01

88

Development of a high gradient magnetic separator using high temperature superconductors  

SciTech Connect

This is the final report of a one-year, Laboratory-Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL). High-gradient magnetic separation (HGMS) is an application of superconducting magnet technology to the process of magnetic separation of solids from other solids, liquids, or gases. The production of both high magnetic fields and large field gradients using superconducting magnet technology has made it possible to separate a previously unreachable but large family of paramagnetic materials. It is possible to separate more than half of the elements in the periodic table using this method. Because HGMS is a physical separation process, no additional or mixed waste is generated. This project sought to develop a high-gradient magnetic separator using a high-temperature superconducting magnet.

Prenger, F.C.; Daney, D.; Daugherty, M.; Hill, D.

1996-09-01

89

CryoFree Final Report  

SciTech Connect

CryoFree, a gamma-ray spectrometer, has been built and successfully tested. This instrument is based on a planar germanium semiconductor detector and is optimized for high-resolution spectroscopy in the range of a 30 keV to a few hundred keV to detect U and Pu. The spectrometer is cooled with a mechanical cryocooler that obviates the need for liquid cryogen. Furthermore, the instrument is battery powered. The combination of mechanical cooling and battery operation allows high-resolution spectroscopy in a highly-portable field instrument. A description of the instrument along with its performance is given.

Burks, M

2006-11-07

90

Simulation and experimental study on magnetic separation of Au loaded biomass from wastewater  

Microsoft Academic Search

Magnetotactic bacterium has the characteristics of both magnetotaxis and adsorbing the precious metal ions, which makes it possible to recycle the precious metal from wastewater in the combination of high gradient magnetic separation. Nickel wires were used as media which producing gradient magnetic field to separate the magnetotactic bacteria (MTB) which had adsorbed Au(III) with high gradient magnetic field from

Song Huiping; Cheng Huaigang; Li Xingang; Cheng Fangqin

2012-01-01

91

Cryo-electron microscopy of viruses  

Microsoft Academic Search

Thin vitrified layers of unfixed, unstained and unsupported virus suspensions can be prepared for observation by cryo-electron microscopy in easily controlled conditions. The viral particles appear free from the kind of damage caused by dehydration, freezing or adsorption to a support that is encountered in preparing biological samples for conventional electron microscopy. Cryo-electron microscopy of vitrified specimens offers possibilities for

Marc Adrian; Jacques Dubochet; Jean Lepault; Alasdair W. McDowall

1984-01-01

92

BPMS FOR THE XFEL CRYO MODULE  

Microsoft Academic Search

The European XFEL is based on superconducting accelerator technology developed in the context of the TESLA collaboration (1). The accelerator itself consists of cryo modules equipped with 8 acceleration cavities, followed by a quadrupole\\/steerer package, a BPM and a HOM absorber. This contribution will present the layout of the BPM system for the cryo modules, describing the monitor itself and

D. Nölle; N. Baboi; K. Knaack; D. Lipka; J. Lund-Nielsen; N. Mildner; R. Neumann; M. Siemens

93

Development of superconducting high gradient magnetic separation system for highly viscous fluid for practical use  

NASA Astrophysics Data System (ADS)

In the industrial plants processing highly viscous fluid such as foods or industrial products, it is necessary to remove the metallic wear debris originating from pipe in manufacturing line which triggers quality loss. In this study, we developed a high gradient magnetic separation (HGMS) system which consists of superconducting magnet to remove the metallic wear debris. The magnetic separation experiment and the particle trajectory simulation were conducted with polyvinyl alcohol (PVA) as a model material (viscosity coefficient was 10 Pa s, which is 10,000 times higher than that in water). In order to develop a magnetic separation system for practical use, the particle trajectory simulation by using solenoidal superconducting magnet was conducted, and the possibility of the magnetic separation for removing ferromagnetic stainless steel (SUS) particles in highly viscous fluid of 10 Pa s was indicated. Based on the results, the number of filters to obtain required separation efficiency was examined to design the practical separation system.

Hayashi, S.; Mishima, F.; Akiyama, Y.; Nishijima, S.

2011-11-01

94

Selective separation of proteins with pH-dependent magnetic nanoadsorbents  

Microsoft Academic Search

Two kinds of unique pH-dependent magnetic nanoadsorbents based on silica coated magnetic nanoparticles (SMNPs) and amino-silica coated magnetic nanoparticles (ASMNPs) have been exploited for selective separation of proteins. With different isoelectric points, silica coated magnetic nanoadsorbents (SMNAs) and amino-silica coated magnetic nanoadsorbents (ASMNAs) can respectively adsorb proteins with different charges. The interactions between proteins and magnetic nanoadsorbents changed with the

Xiaoxiao He; Yingjie Chen; Kemin Wang; Ping Wu; Ping Gong; Hailing Huo

2007-01-01

95

Magnetic separator having high rate of field change capability  

SciTech Connect

This paper describes a combination of a large magnet for classifying magnetic particles from a passing fluid stream of magnetic and nonmagnetic particles. The large magnet including a central canister having a diameter exceeding 60-inches. It comprises: first and second manifolds for communicating; magnetic coils; a magnetic field; a power supply; first solid state rectifier circuit; second solid state rectifier circuit; first power supply drive means; and, second power supply drive means.

Tillotson, J.A.; Crowe, K.M.

1990-12-18

96

Method and apparatus for separating materials magnetically. [Patent application; iron pyrite from coal  

DOEpatents

Magnetic and nonmagnetic materials are separated by passing stream thereof past coaxial current-carrying coils which produce a magnetic field wherein intensity varies sharply with distance radially of the axis of the coils.

Hise, E.C. Jr.; Holman, A.S.; Friedlaender, F.J.

1980-11-06

97

New process for placer gold recovery by means of magnetic separation  

Microsoft Academic Search

The authors present calculations and results of a study of magnetic systems intended to recover gold. A mathematical model of the separation in magnetic fluid is described. The complex of separators KC3-1 was developed. Industrial-scale testing results are shown. Gold recovery at all stages of magnetic separation is 91.1-99.5%. The feed rate of this complex is 100 kg\\/h

R. D. Smolkin; Y. M. Garin; V. S. Krokhmal; O. P. Sayko

1992-01-01

98

High efficiency protein separation with organosilane assembled silica coated magnetic nanoparticles  

Microsoft Academic Search

This work describes the development of high efficiency protein separation with functionalized organosilanes on the surface of silica coated magnetic nanoparticles. The magnetic nanoparticles were synthesized with average particle size of 9 nm and silica coated magnetic nanoparticles were obtained by controlling the coating thicknesses on magnetic nanoparticles. The silica coating thickness could be uniformly sized with a diameter of

Jeong Ho Chang; Ki Ho Kang; Jinsub Choi; Young Keun Jeong

2008-01-01

99

SUPERCONDUCTING OPEN-GRADIENT MAGNETIC SEPARATION FOR THE PRETREATMENT OF RADIOACTIVE OR MIXED WASTE VITRIFICATION FEEDS  

EPA Science Inventory

Scientists need to gain a better understanding of the magnetic separation processes that can be used to separate deleterious constituents (crystalline, amorphous, and colloidal) in vitrification feed streams for borosilicate glass production without adding chemicals or generating...

100

Superconducting Open-Gradient Magnetic Separation for the Pretreatment of Radioactive or Mixed Waste Vitrification Feeds.  

National Technical Information Service (NTIS)

An open-gradient magnetic separation (OGMS) process is being considered to separate deleterious elements from radioactive and mixed waste streams prior to vitrification or stabilization. By physically segregating solid wastes and slurries based on the mag...

L. Nunez M. D. Kaminsky R. D. Doctor C. Crawfor J. A. Ritter

1999-01-01

101

Magnetic fluid separation of gold-containing products in the vibration field  

Microsoft Academic Search

New data on the process of the magnetic fluid (MF) separation, which is based on the ponderomotive effect of the magnetized\\u000a separation medium—or ferromagnetic fluid (FMF) on the nonmagnetic bodies arranged in it—are obtained. The magnetization of\\u000a the FMF in a nonuniform magnetic field increases the strength of the field of mass forces affecting the FMF and, as a consequence,

A. M. Pan’shin; S. I. Evdokimov; S. V. Artemov

2009-01-01

102

Enhanced separation of magnetic and diamagnetic particles in a dilute ferrofluid  

NASA Astrophysics Data System (ADS)

Traditional magnetic field-induced particle separations take place in water-based diamagnetic solutions, where magnetic particles are captured while diamagnetic particles flow through without being affected by the magnetic field. We demonstrate that replacing the diamagnetic aqueous medium with a dilute ferrofluid can significantly increase the throughput of magnetic and diamagnetic particle separation. This enhancement is attributed to the simultaneous positive and negative magnetophoresis of magnetic and diamagnetic particles, respectively, in a ferrofluid. The particle transport behaviors in both ferrofluid- and water-based separations are predicted using an analytical model.

Liang, Litao; Zhang, Cheng; Xuan, Xiangchun

2013-06-01

103

Application of high temperature superconductors to high-gradient magnetic separation  

SciTech Connect

High Gradient Magnetic Separation (HGMS) is a powerful technique which can be used to separate widely dispersed contaminants from a host material, This technology can separate magnetic solids from other solids, liquids or gases. As the name implies HGMS uses large magnetic field gradients to separate ferromagnetic and paramagnetic particles. HGMS separators usually consist of a high-field solenoid magnet, the bore of which contains a fine-structured, ferromagnetic matrix material. The matrix material locally distorts the magnetic field and creates large field gradients in the vicinity of the matrix elements. These elements then become trapping sites for magnetic particles and are the basis for the magnetic separation. In this paper we discuss the design and construction of a prototype HGMS unit using a magnet made with high temperature superconductors (HTS). The prototype consists of an outer vacuum vessel which contains the HTS solenoid magnet The magnet is surrounded by a thermal radiation shield and multilayer insulation (MLI) blankets. The magnet, thermal shield and current leads all operate in a vacuum and are cooled by a cryocooler. High temperature superconducting current leads are used to reduce the heat leak from the ambient environment to the HTS magnet.

Daugherty, M.A.; Prenger, F.C.; Hill, D.D.; Daney, D.E.; Worl, L.W.; Schake, A.R.; Padilla, D.D.

1994-06-01

104

Application of high temperature superconductors to high-gradient magnetic separation  

NASA Astrophysics Data System (ADS)

High Gradient Magnetic Separation (HGMS) is a powerful technique which can be used to separate widely dispersed contaminants from a host material, This technology can separate magnetic solids from other solids, liquids, or gases. As the name implies, HGMS uses large magnetic field gradients to separate ferromagnetic and paramagnetic particles. HGMS separators usually consist of a high-field solenoid magnet, the bore which contains a fine-structured, ferromagnetic matrix material. The matrix material locally distorts the magnetic field and creates large field gradients in the vicinity of the matrix elements. These elements then become trapping sites for magnetic particles and are the basis for the magnetic separation. In this paper, we discuss the design and construction of a prototype HGMS unit using a magnet made with high temperature superconductors (HTS). The prototype consists of an outer vacuum vessel which contains the HTS solenoid magnet. The magnet is surrounded by a thermal radiation shield and multilayer insulation (MLI) blankets. The magnet, thermal shield, and current leads all operate in a vacuum and are cooled by a cryocooler. High temperature superconducting current leads are used to reduce the heat leak from the ambient environment to the HTS magnet.

Daugherty, M. A.; Prenger, F. C.; Hill, D. D.; Daney, D. E.; Worl, L. W.; Schake, A. R.; Padilla, D. D.

105

Magnetic Separation Immunoassay for Digoxin in Plasma with Flow Injection Fluorescence Detection  

Microsoft Academic Search

Immunoassay (IA) is a sensitive and selective approach for low level quantitation of drugs. Magnetic separation immunoassays use magnetic beads to facilitate the separation of bound labeled antigens from free antigens in solution. Digoxin was chosen for this study because low level analysis (ng?mL -1) in biological samples isrequired, antibodies to digoxin were commercially available and derivatization procedures for fluorescence

Zhe Tang; Kerstin Graefe; Clark March; H. Thomas Karnes

2004-01-01

106

Magnetic separation of particles and cells in ferrofluid flow through a straight microchannel using two offset magnets  

NASA Astrophysics Data System (ADS)

The separation of particles and cells is critical in many chemical and biological applications. This work presents a simple idea for utilizing a pair of permanent magnets to continuously separate diamagnetic particles and cells in ferrofluid flow through a straight microchannel. The first magnet is placed close to the microchannel for focusing the particle mixture to a single stream without the use of a sheath flow. The second magnet, which is offset from the first magnet and placed farther from the channel, is to displace the aligned particles to dissimilar flow paths for a continuous sorting. This idea is first demonstrated through the separation of 3 ?m- and 10 ?m-diameter polystyrene particles, where the effects of flow speed and magnet distance are both examined. The experimental data are found to fit well with the predictions of an analytical model. Furthermore, a continuous separation of live yeast cells from 10 ?m polystyrene particles is implemented in the same device.

Zeng, Jian; Deng, Yanxiang; Vedantam, Pallavi; Tzeng, Tzuen-Rong; Xuan, Xiangchun

2013-11-01

107

Coupled particle-fluid transport and magnetic separation in microfluidic systems with passive magnetic functionality  

NASA Astrophysics Data System (ADS)

A study is presented of coupled particle-fluid transport and field-directed particle capture in microfluidic systems with passive magnetic functionality. These systems consist of a microfluidic flow cell on a substrate that contains embedded magnetic elements. Two systems are considered that utilize soft- and hard-magnetic elements, respectively. In the former, an external field is applied to magnetize the elements, and in the latter, they are permanently magnetized. The field produced by the magnetized elements permeates into the flow cell giving rise to an attractive force on magnetic particles that flow through it. The systems are studied using a novel numerical/closed-form modelling approach that combines numerical transport analysis with closed-form field analysis. Particle-fluid transport is computed using computational fluid dynamics (CFD), while the magnetic force that governs particle capture is obtained in closed form. The CFD analysis takes into account dominant particle forces and two-way momentum transfer between the particles and the fluid. The two-way particle-fluid coupling capability is an important feature of the model that distinguishes it from more commonly used and simplified one-way coupling analysis. The model is used to quantify the impact of two-way particle-fluid coupling on both the capture efficiency and the flow pattern in the systems considered. Many effects such as particle-induced flow-enhanced capture efficiency and flow circulation are studied that cannot be predicted using one-way coupling analysis. In addition, dilute particle dispersions are shown to exhibit significant localized particle-fluid coupling near the capture regions, which contradicts the commonly held view that two-way coupling can be ignored when analysing high-gradient magnetic separation involving such particle systems. Overall, the model demonstrates that two-way coupling needs to be taken into account for rigorous predictions of capture efficiency, especially for applications involving high particle loading and/or low flow rates. It is computationally more efficient and accurate than purely numerical models and should prove useful for the rational design and optimization of novel magnetophoretic microsystems.

Khashan, Saud A.; Furlani, Edward P.

2013-03-01

108

Cryo-Electron Tomography of Rubella Virus  

PubMed Central

Rubella virus is the only member of the Rubivirus genus within the Togaviridae family and is the causative agent of the childhood disease known as rubella or German measles. Here, we report the use of cryo-electron tomography to examine the three-dimensional structure of rubella virions and compare their structure to that of Ross River virus, a togavirus belonging the genus Alphavirus. The ectodomains of the rubella virus glycoproteins, E1 and E2, are shown to be organized into extended rows of density, separated by 9 nm on the viral surface. We also show that the rubella virus nucleocapsid structure often forms a roughly spherical shell which lacks high density at its center. While many rubella virions are approximately spherical and have dimensions similar to that of the icosahedral Ross River virus, the present results indicate that rubella exhibits a large degree of pleomorphy. In addition, we used rotation function calculations and other analyses to show that approximately spherical rubella virions lack the icosahedral organization which characterizes Ross River and other alphaviruses. The present results indicate that the assembly mechanism of rubella virus, which has previously been shown to differ from that of the alphavirus assembly pathway, leads to an organization of the rubella virus structural proteins that is different from that of alphaviruses.

Battisti, Anthony J.; Yoder, Joshua D.; Plevka, Pavel; Winkler, Dennis C.; Mangala Prasad, Vidya; Kuhn, Richard J.; Frey, Teryl K.; Steven, Alasdair C.

2012-01-01

109

Cryo-comminution of plastic waste.  

PubMed

Recycling of plastics is a big issue in terms of environmental sustainability and of waste management. The development of proper technologies for plastic recycling is recognised as a priority. To achieve this aim, the technologies applied in mineral processing can be adapted to recycling systems. In particular, the improvement of comminution technologies is one of the main actions to improve the quality of recycled plastics. The aim of this work is to point out suitable comminution processes for different types of plastic waste. Laboratory comminution tests have been carried out under different conditions of temperature and sample pre-conditioning adopting as refrigerant agents CO2 and liquid nitrogen. The temperature has been monitored by thermocouples placed in the milling chamber. Also different internal mill screens have been adopted. A proper procedure has been set up in order to obtain a selective comminution and a size reduction suitable for further separation treatment. Tests have been performed on plastics coming from medical plastic waste and from a plant for spent lead batteries recycling. Results coming from different mill devices have been compared taking into consideration different indexes for representative size distributions. The results of the performed tests show as cryo-comminution improves the effectiveness of size reduction of plastics, promotes liberation of constituents and increases specific surface size of comminuted particles in comparison to a comminution process carried out at room temperature. PMID:15288298

Gente, Vincenzo; La Marca, Floriana; Lucci, Federica; Massacci, Paolo; Pani, Eleonora

2004-01-01

110

D0 Cryo CC Heater Installation  

SciTech Connect

Nine pairs of heaters are installed in the bottom of the CC pressure vessel.The physical layout is shown in the CC internal development drawing, D0 dwg. 3740.510-ME-255523. Electrically the heater system is a delta configuration. Electrical details are found on D0 dwg. 3740.515EC-273761. The feedthrough connectors for power to the heaters are located in the instrumentation box. Connector positions are found on D0 dwg.3740.515-EC-273760. Original sketches for the above named drawings are included in this document. The heaters and wiring were cleaned various times prior to and after installation with ethyl a1chohol. At various stages in the installation hi-pot and continuity tests were successfully accomplished to verify the integrity of the system. The fmal hi-pot numbers are included in the documentation. The heaters and wiring are kept separated from thermometry and purity cell wiring by SS sheetmetal barriers. The fabrication, testing and installation was completed by M. Hentges and his crew from AD/Cryo.

Urbin, J.; /Fermilab

1991-03-16

111

Cryo-balloon reconstruction from two views  

Microsoft Academic Search

Atrial fibrillation is a major cause of stroke. Its treatment is performed under fluoroscopic image guidance. Augmented fluoroscopy has become a useful tool during the ablation procedure for navigation under X-ray. Unfortunately, current navigation systems do not provide tools to localize and visualize a cryo-balloon catheters in 3-D. This is why we present a new approach to reconstruct the cryo-ballon

A. Kleinoeder; A. Brost; F. Bourier; M. Koch; K. Kurzidim; J. Hornegger; N. Strobel

2011-01-01

112

Magnetic particles for the separation and purification of nucleic acids  

Microsoft Academic Search

Nucleic acid separation is an increasingly important tool for molecular biology. Before modern technologies could be used, nucleic acid separation had been a time- and work-consuming process based on several extraction and centrifugation steps, often limited by small yields and low purities of the separation products, and not suited for automation and up-scaling. During the last few years, specifically functionalised

Sonja Berensmeier

2006-01-01

113

Desulfurization and Deashing of Solvent Refined Coal (SRC-I) by High Gradient Magnetic Separation Techniques  

Microsoft Academic Search

A pilot-scale high gradient magnetic separations (HGMS) system was assembled to investigate the magnetic separation of ash-forming solids and inorganic sulfur from liquefied coal. The liquefied coal studied was a diluted intermediate product obtained from the DOE-sponsored Tacoma SRC-I pilot plant (50 t\\/d coal capacity). The magnetic characteristics and particle size distribution of the Tacoma SRC-I liquefied coal were optimized

L. Petrakis; P. F. Ahner; F. E. Kiviat

1981-01-01

114

Experimental investigation into the application of a magnetic cyclone for dense medium separation  

Microsoft Academic Search

The density differential between the overflow and underflow streams is one of the critical measurable parameters in the operation of dense medium cyclones. Our investigation of the application of a magnetic cyclone to dense medium separation showed that by a judicious positioning of a solenoid magnet along the axis of the cyclone, and by adjusting the strength of the magnetic

J Svoboda; C Coetzee; Q. P Campbell

1998-01-01

115

Magnetic separation of materials. (Latest citations from the EI Compendex*plus database). Published Search  

SciTech Connect

The bibliography contains citations concerning the design, development, and testing of equipment which uses magnetism as a means of separating and purifying ores and minerals. This technology is used extensively in cleaning fossil fuels, separating fly ash constituents, mineral separations, beneficiation of ores, and other ore processing systems. The articles presented describe various operating systems, separating techniques and variables, and high-gradient magnetic separation which can be used with certain metal oxides and other paramagnetic materials. (Contains a minimum of 214 citations and includes a subject term index and title list.)

Not Available

1994-04-01

116

Magnetic separation of materials. (Latest citations from the Compendex database). Published Search  

SciTech Connect

The bibliography contains citations concerning the design, development, and testing of equipment which uses magnetism as a means of separating and purifying ores and minerals. This technology is used extensively in cleaning fossil fuels, separating fly ash constituents, mineral separations, beneficiation of ores, and other ore processing systems. The articles presented describe various operating systems, separating techniques and variables, and high-gradient magnetic separation which can be used with certain metal oxides and other paramagnetic materials. (Contains a minimum of 209 citations and includes a subject term index and title list.)

Not Available

1993-06-01

117

A TIME-DEPENDENT MODEL FOR MAGNETIC RECONNECTION IN THE PRESENCE OF A SEPARATOR  

SciTech Connect

We present a model for separator reconnection due to an isolated reconnection process. Separator reconnection is a process which occurs in the neighborhood of a distinguished field line (the separator) connecting two null points of a magnetic field. It is, for example, important for the dynamics of magnetic flux at the dayside magnetopause and in the solar corona. We find that, above a certain threshold, such a reconnection process generates new separators, which leads to a complex system of magnetic flux tubes connecting regions of previously separated flux. Our findings are consistent with the findings of large numbers of separators in numerical simulations. We discuss how to measure and interpret the reconnection rate in a configuration with multiple separators.

Wilmot-Smith, A. L.; Hornig, G., E-mail: antonia@maths.dundee.ac.uk [Division of Mathematics, University of Dundee, Dundee DD1 4HN (United Kingdom)

2011-10-20

118

Low magnetic-field separation system for metal-loaded magnetotactic bacteria  

NASA Astrophysics Data System (ADS)

Magnetotactic bacteria (MTB) offer a unique approach to metal accumulation and separation from water systems. This paper proposes an integrated separator design, for the production of MTB, the metal uptake phase and their subsequent separation. Applied magnetic fields are used to orientate the bacteria, so that they swim in a direction resulting in their removal.

Bahaj, A. S.; James, P. A. B.; Moeschler, F. D.

1998-01-01

119

Highly sensitive and rapid detection of Pseudomonas aeruginosa based on magnetic enrichment and magnetic separation.  

PubMed

A method for highly sensitive and rapid detection of Pseudomonas aeruginosa, based on magnetic enrichment and magnetic separation, is described in this paper. The magnetic nanoparticles (MNPs) were applied to adsorb genome DNA after the sample was lysed. The DNA binding MNPs were directly subjected to polymerase chain reaction (PCR) to amplify gyrB specific sequence of Pseudomonas aeruginosa. The biotin labeled PCR products were detected by chemiluminescence when they were successively incubated with the probes-modified MNPs and alkaline phosphatase (ALP) labeled streptavidin (SA). Agarose gel electrophoresis analyses approved the method of in situ PCR to be highly reliable. The factors which could affect the chemiluminiscence were studied in detail. The results showed that the MNPs of 400 nm in diameter are beneficial to the detection. The sequence length and the binding site of the probe with a target sequence have obvious effects on the detection. The optimal concentration of the probes, hybridization temperature and hybridization time were 10 ?M, 60 ºC and 60 mins, respectively. The method of in situ PCR based on MNPs can greatly improve the utilization rate of the DNA template ultimately enhancing the detection sensitivity. Experiment results proved that the primer and probe had high specificity, and Pseudomonas aeruginosa was successfully detected with detection limits as low as 10 cfu/mL by this method, while the detection of a single Pseudomonas aeruginosa can also be achieved. PMID:23424183

Tang, Yongjun; Zou, Jun; Ma, Chao; Ali, Zeeshan; Li, Zhiyang; Li, Xiaolong; Ma, Ninging; Mou, Xianbo; Deng, Yan; Zhang, Liming; Li, Kai; Lu, Guangming; Yang, Haowen; He, Nongyue

2013-01-16

120

Highly Sensitive and Rapid Detection of Pseudomonas aeruginosa Based on Magnetic Enrichment and Magnetic Separation  

PubMed Central

A method for highly sensitive and rapid detection of Pseudomonas aeruginosa, based on magnetic enrichment and magnetic separation, is described in this paper. The magnetic nanoparticles (MNPs) were applied to adsorb genome DNA after the sample was lysed. The DNA binding MNPs were directly subjected to polymerase chain reaction (PCR) to amplify gyrB specific sequence of Pseudomonas aeruginosa. The biotin labeled PCR products were detected by chemiluminescence when they were successively incubated with the probes-modified MNPs and alkaline phosphatase (ALP) labeled streptavidin (SA). Agarose gel electrophoresis analyses approved the method of in situ PCR to be highly reliable. The factors which could affect the chemiluminiscence were studied in detail. The results showed that the MNPs of 400 nm in diameter are beneficial to the detection. The sequence length and the binding site of the probe with a target sequence have obvious effects on the detection. The optimal concentration of the probes, hybridization temperature and hybridization time were 10 ?M, 60 ºC and 60 mins, respectively. The method of in situ PCR based on MNPs can greatly improve the utilization rate of the DNA template ultimately enhancing the detection sensitivity. Experiment results proved that the primer and probe had high specificity, and Pseudomonas aeruginosa was successfully detected with detection limits as low as 10 cfu/mL by this method, while the detection of a single Pseudomonas aeruginosa can also be achieved.

Tang, Yongjun; Zou, Jun; Ma, Chao; Ali, Zeeshan; Li, Zhiyang; Li, Xiaolong; Ma, Ninging; Mou, Xianbo; Deng, Yan; Zhang, Liming; Li, Kai; Lu, Guangming; Yang, Haowen; He, Nongyue

2013-01-01

121

High efficiency protein separation with organosilane assembled silica coated magnetic nanoparticles  

Microsoft Academic Search

This work describes the development of high efficiency protein separation with functionalized organosilanes on the surface of silica coated magnetic nanoparticles. The magnetic nanoparticles were synthesized with average particle size of 9 nm and silica coated magnetic nanoparticles were obtained by controlling the coating thicknesses on magnetic nanoparticles. The silica coating thickness could be uniformly sized with a diameter of 10–40 nm

Jeong Ho Chang; Ki Ho Kang; Jinsub Choi; Young Keun Jeong

2008-01-01

122

Magnetic and fluorescence-encoded polystyrene microparticles for cell separation  

Microsoft Academic Search

Materials assisting with the efforts of cell isolation are attractive for numerous biomedical applications including tissue engineering and cell therapy. Here, we have developed surface modification methods on microparticles for the purposes of advanced cell separation. Iron oxide nanoparticles were incorporated into 200 mum polystyrene microparticles for separation of particle-bound cells from non-bound cells in suspension by means of a

Diana Bradbury; Emily J. Anglin; Sheree Bailey; Peter J. Macardle; Michael Fenech; Helmut Thissen; Nicolas H. Voelcker

2008-01-01

123

Development of a dielectric barrier discharge (DBD) cryo-microplasma: generation and diagnostics  

NASA Astrophysics Data System (ADS)

We developed a cryo-microplasma, which can continuously control gas temperature below room temperature and below the freezing point of water. To develop the cryo-microplasma, we first developed an atmospheric-pressure low-temperature microplasma that can suppress the increase in its gas temperature. Helium gas was employed, which was generated in open air. The average estimated electron density and temperature were 108-109 cm-3 and 4-5 eV, respectively, independent of the applied voltage. Then, helium gas, which was the working gas of the atmospheric-pressure low-temperature microplasma, was cooled by liquid nitrogen to generate an atmospheric-pressure cryo-microplasma in open air. We observed the generation of frost around the quartz tube in which the plasma was generated and an increase in atomic oxygen emission by optical emission spectroscopy. Finally, to avoid the generation of frost, a cryo-microplasma was generated in a reactor chamber separated from open air. Helium, nitrogen and oxygen were employed as working gases. Using thermocouples and by estimation from the nitrogen rotational temperature, we verified that the gas temperature of the cryo-microplasma was much lower (Tg ? 180-300 K) than that of the conventional atmospheric-pressure low-temperature plasma (above 300 K).

Ishihara, Daisuke; Noma, Yuri; Stauss, Sven; Sai, Masaki; Tomai, Takaaki; Terashima, Kazuo

2008-08-01

124

Magnetic separation technique for groundwater by five HTS melt-processed bulk magnets arranged in a line  

NASA Astrophysics Data System (ADS)

A magnetic separation study for groundwater purification has been practically conducted by using the multi-pole magnet system. The magnetic pole was composed of 10 open magnetic spaces by arranging five HTS melt-processed bulk magnets in a line in a vacuum sheath. The individual bulk magnets were activated by feeding intense pulsed magnetic fields up to 6 T. The magnetic field distribution was estimated with respect to various pole arrangements. The actual groundwater samples of Sanjo City were processed so as to form large precipitates by adding the coagulant and pH controlling. The maximum separation ratio of the iron-bearing precipitates has exceeded over 70% when slurry water was exposed to 10 magnetic poles of up to 2.5 T at a flowing rate of less than 4.8 l/min. An obvious attraction of flocks to the magnetic poles was observed even when the water contains no magnetite powder at the flow rate of 1.01 l/min. This implies the validity of the multi-pole magnet system with respect to the actual application to water purification.

Oka, T.; Seki, H.; Kimura, T.; Mimura, D.; Fukui, S.; Ogawa, J.; Sato, T.; Ooizumi, M.; Fujishiro, H.; Hayashi, H.; Yokoyama, K.; Stiehler, C.

2011-11-01

125

Magnetic microspheres prepared by redox polymerization used in a cell separation based on gangliosides.  

PubMed

A facile method is described for making magnetic microspheres that bind specifically to cell surfaces, in order to separate cells magnetophoretically. Control over the sizes of the spheres is effected by using their magnetic cores as part of a redox polymerization system. The use of the microspheres is demonstrated with a separation involving C-1300 neuroblastoma cells, 10% of which express the ganglioside GM1 in their membranes. The GM1-containing cells were separated with better than 99% purity, while the deficient cells were obtained at least 98% pure. The separation, which was carried out under sterile conditions, required only 6 minutes. PMID:653356

Kronick, P L; Campbell, G L; Joseph, K

1978-06-01

126

Combined Centrifugal Separation-Flotation-Magnetic Concentration Flowsheet for Treatment of Wolframite Slimes.  

National Technical Information Service (NTIS)

Based on testwork and plant practice a flowsheet has been developed combining centrifugal separation with flotation and magnetic concentration for the treatment of wolframite slimes to yield a high-grade tungsten concentrate. In May, 1977, laboratory and ...

P. Liu D. Wang

1987-01-01

127

Magnetically separable nanoferrite-anchored glutathione: Aqueous homocoupling of arylboronic acids under microwave irradiation  

EPA Science Inventory

A highly active, stable and magnetically separable glutathione based organocatalyst provided good to excellent yields to symmetric biaryls in the homocoupling of arylboronic acids under microwave irradiation. Symmetrical biaryl motifs are present in a wide range of natural p...

128

Separation of binary granular mixtures under vibration and differential magnetic levitation force.  

PubMed

The application of both a strong magnetic field and a magnetic field gradient to a diamagnetic or paramagnetic material can produce a vertical force that acts in concert with the force of gravity. We consider a binary granular mixture in which the two components have different magnetic susceptibilities and therefore experience different effective forces of gravity when subjected to an inhomogeneous magnetic field. Under vertical vibration, such a mixture may rapidly separate into regions almost pure in the two components. We investigate the conditions for this behavior, studying the speed and completeness of separation as a function of differential effective gravity and the frequency and amplitude of vibration. The influence of the cohesive magnetic dipole-dipole interactions on the separation process is also investigated. In our studies insight is gained through the use of a molecular dynamics simulation model. PMID:15783320

Catherall, A T; López-Alcaraz, P; Sánchez, P; Swift, Michael R; King, P J

2005-02-23

129

Quantifying of magnetically separated particles using Hall-effect sensing  

NASA Astrophysics Data System (ADS)

In this paper, we present a modeling of a captured ferromagnetic particles quantifying method based on the detection and evaluation of the magnetic field variation caused by the particle static buildup. The detecting element is a Hall-effect sensor (probe) associated to the particle capture element which is an electromagnet with iron core. From a known value of the magnetic field measured at the particle static buildup locality, we predict the particle global concentration in the treated material sample (powder or liquid). This prediction is achieved by solving the inverse problem for the captured particles magnetic field variation. Such a resolution is based on an iterative resolution of the forward problem until obtaining the global particle concentration related to the measured value of the field variation. Because an exact value can not be obtained we retain the value that minimizes an error function. To minimize such a function we have used the Tabu searching method.

Mehasni, R.; Latreche, M. E.; Feliachi, M.

2007-08-01

130

Electric charge separation in strong transient magnetic fields  

SciTech Connect

We discuss various mechanisms for the creation of an asymmetric charge fluctuation with respect to the reaction plane among hadrons emitted in relativistic heavy-ion collisions. We show that such mechanisms exist in both the hadronic gas and the partonic phases of quantum chromodynamics. The mechanisms considered here all require the presence of a strong magnetic field (the 'chiral magnetic effect'), but they do not involve parity or charge-parity violations. We analyze how a transient local electric current fluctuation generated by the chiral magnetic effect can dynamically evolve into an asymmetric charge distribution among final-state hadrons in momentum space. We estimate the magnitude of the event-by-event fluctuations of the final-state charge asymmetry owing to partonic and hadronic mechanisms.

Asakawa, Masayuki [Department of Physics, Osaka University, Toyonaka 560-0043 (Japan); Majumder, Abhijit [Department of Physics, Ohio State University, Columbus, Ohio 43210 (United States); Mueller, Berndt [Department of Physics and Center for Theoretical and Mathematical Sciences, Duke University, Durham, North Carolina 27708 (United States)

2010-06-15

131

Roasting reduction-magnetic separation of oolitic-hematite and preparation of cementitious materials  

Microsoft Academic Search

Aimed at utilizing oolitic hematite comprehensively and reducing discharge of solid wastes, a series of experiments to extract iron by coal-based roasting reduction-magnetic separation technology and prepare cementitious materials by using magnetic separation tailings were carried out. The experiment results show that when the amount of reductant is 30wt%, the roasting temperature is 1200?` , the reduction time is 60min

Keqing Li; Ming Zhu; Wen Ni; Baoshun Liu

2011-01-01

132

Affinity separation in magnetically stabilized fluidized beds: synthesis and performance of packing materials  

SciTech Connect

A magnetically stabilized fluidized-bed separator designed to test the use of pellicular, ferromagnetic affinity chromatography packing materials has been developed. A wire wound solenoid was used to produce the magnetic field. The ferromagnetic packing material is comprised of a magnetite-containing, polyurethane gel coated onto polystyrene beads. The gel contains free carboxyl groups. These were carbodiimide-coupled to soy trypsin inhibitor and the material used for trypsin purification. Narrow-band affinity chromatography was carried out in packed-bed, fluidized-bed, and magnetically stabilized, fluidized-bed separators. Pressure drop, capacity, dilution, and peak asymmetry were evaluated for each type of separator. The three types provide comparable efficiency but the fluidized separators exhibit a much lower pressure drop. As might be expected, fluidized-bed separators perform well for affinity chromatography (large k') but poorly for size exclusion chromatography.

Lochmueller, C.H.; Wigman, L.S.

1987-11-01

133

Removal of algal blooms from freshwater by the coagulation-magnetic separation method.  

PubMed

This research investigated the feasibility of changing waste into useful materials for water treatment and proposed a coagulation-magnetic separation technique. This technique was rapid and highly effective for clearing up harmful algal blooms in freshwater and mitigating lake eutrophication. A magnetic coagulant was synthesized by compounding acid-modified fly ash with magnetite (Fe(3)O(4)). Its removal effects on algal cells and dissolved organics in water were studied. After mixing, coagulation, and magnetic separation, the flocs obtained from the magnet surface were examined by SEM. Treated samples were withdrawn for the content determination of chlorophyll-a, turbidity, chemical oxygen demand (COD), total nitrogen, and total phosphorus. More than 99 % of algal cells were removed within 5 min after the addition of magnetic coagulant at optimal loadings (200 mg L(-1)). The removal efficiencies of COD, total nitrogen, and phosphorus were 93, 91, and 94 %, respectively. The mechanism of algal removal explored preliminarily showed that the magnetic coagulant played multiple roles in mesoporous adsorption, netting and bridging, as well as high magnetic responsiveness to a magnetic field. The magnetic-coagulation separation method can rapidly and effectively remove algae from water bodies and greatly mitigate eutrophication of freshwater using a new magnetic coagulant. The method has good performance, is low cost, can turn waste into something valuable, and provides reference and directions for future pilot and production scale-ups. PMID:22767355

Liu, Dan; Wang, Peng; Wei, Guanran; Dong, Wenbo; Hui, Franck

2012-07-06

134

Affinity adsorption and separation behaviors of avidin on biofunctional magnetic nanoparticles binding to iminobiotin  

Microsoft Academic Search

Knowing the adsorption behavior of target proteins on biofunctional magnetic nanoparticles is of great importance for the separation and purification of proteins. Adsorption behaviors of avidin on biofunctional magnetic nanoparticles binding to iminobiotin were investigated under different conditions of temperature, pH, ionic strength, and feed avidin concentration. Biofunctionalization of the non-functional nanoparticles was performed, coupled with iminobiotin. Characterization of the

Shuguo Sun; Meihu Ma; Ning Qiu; Xi Huang; Zhaoxia Cai; Qun Huang; Xin Hu

2011-01-01

135

Hyperfine Structure Separation, Nuclear Magnetic Moment, and Hyperfine Structure Anomaly of CESIUM131  

Microsoft Academic Search

The atomic-beam magnetic-resonance method was used to obtain the ; hyperfine structure separation DELTA \\/sub nu \\/, the nuclear magnetic dipole ; momert mu \\/sub I\\/, and the hyperfine structure anomaly DELTA , of Cs¹³¹. ; Independent values of mu \\/sub I\\/ and DELTA nu \\/ were obtained by observing one ; of the DELTA F = plus or minus

Richard Dixon Worley

1963-01-01

136

Extraction of heavy metals using microorganisms and high gradient magnetic separation  

Microsoft Academic Search

It is pointed out that a large number of microorganisms have affinity to ingest or precipitate ion species onto their surfaces. In the case of magnetic ionic species, magnetic separation methods could be applied to remove the ion-loaded organisms from the surroundings. A wide range of metal ions were studied in the experiments described. The results show that the microorganisms

A. S. Bahaj; D. C. Ellwood; J. H. P. Watson

1991-01-01

137

A novel high-gradient magnetic separator (HGMS) design for biotech applications  

Microsoft Academic Search

A novel high-gradient magnetic separator (HGMS) has been designed to meet the strong requirements of biotech processes to grant high product yield, efficient cleanability and low operating costs. The novel design using a rotary permanent magnet leads to an \\

C. Hoffmann; M. Franzreb; W. H. Holl

2002-01-01

138

Optimized high gradient magnetic separation for isolation of Plasmodium-infected red blood cells  

Microsoft Academic Search

BACKGROUND: Highly purified infected red blood cells (irbc), or highly synchronized parasite cultures, are regularly required in malaria research. Conventional isolation and synchronization rely on density and osmotic fragility of irbc, respectively. High gradient magnetic separation (HGMS) offers an alternative based on intrinsic magnetic properties of irbc, avoiding exposure to chemicals and osmotic stress. Successful HGMS concentration in malaria research

Sebastian C Bhakdi; Annette Ottinger; Sangdao Somsri; Panudda Sratongno; Peeranad Pannadaporn; Pattamawan Chimma; Prida Malasit; Kovit Pattanapanyasat; Hartmut PH Neumann

2010-01-01

139

Removal of arsenic from geothermal water by high gradient magnetic separation  

Microsoft Academic Search

On-site experimentation of high gradient magnetic separation (HGMS) for arsenic removal from geothermal water has been conducted using a high-Tc superconducting magnet. This development of an effective method for decontamination of geothermal water is currently being done at the Kakkonda geothermal power plant in Shizukuishi, Iwate, Japan. In order to enhance the magnetic properties of the arsenic-containing particles in geothermal

A. Chiba; H. Okada; T. Tada; H. Kudo; H. Nakazawa; K. Mitsuhashi; T. Ohara; H. Wada

2002-01-01

140

Investigation for Magnetic Separation of Oxygen from Supercritical Air Near the Maxcondentherm Point  

Microsoft Academic Search

In an effort to develop a highly effective separation technology for oxygen operating in the liquefied natural gas (LNG) temperature range, the magnetic separation of oxygen from supercritical air was investigated using a laser holography interferometer. The experiment was carried out near the maxcondentherm (MC) point. For purposes of comparison, the same operation was carried out using supercritical nitrogen. Here,

A. Nakano; M. Shiraishi

2004-01-01

141

ELECTRON TRANSPORT IN CORONAL LOOPS: THE INFLUENCE OF THE EXPONENTIAL SEPARATION OF MAGNETIC FIELD LINES  

SciTech Connect

Observations by the TRACE spacecraft have shown that coronal emission in the extreme ultraviolet is characterized by filamentary structures within coronal loops, with transverse sizes close to the instrumental resolution. Starting from the observed filament widths and using the concepts of braided magnetic fields, an estimate of the turbulence level in the coronal loops can be obtained. Magnetic turbulence in the presence of a background magnetic field can be strongly anisotropic, and such anisotropy influences the separation of magnetic field lines, as well as the magnetic field line diffusion coefficient. Careful computations of the magnetic field line diffusion coefficient D{sub m} and of the rate of exponential separation of magnetic field lines h, also allowing for the possibility of anisotropic magnetic turbulence, enable computation of the effective perpendicular diffusion coefficient for electrons. When compared with observations this yields magnetic turbulence levels on the order of {delta}B/B {sub 0} = 0.05-0.7, which are larger than previous estimates. These values of the magnetic fluctuation level support the idea that magnetic turbulence can contribute to coronal heating by means of MHD turbulence dissipation. It is also found that field line transport is not governed by the quasilinear regime, but by a nonlinear regime which includes an intermediate and the percolation regimes.

Bitane, R. [Universite de Nice-Sophia Antipolis, CNRS, Observatoire de la Cote d'Azur, Laboratoire Cassiopee, Blvd. De l'Observatoire, 06300 Nice (France); Zimbardo, G.; Veltri, P., E-mail: zimbardo@fis.unical.i [Dipartimento di Fisica, Universita della Calabria, Ponte P. Bucci, Cubo 31C, I-87036 Arcavacata di Rende (Italy)

2010-08-20

142

Selective separation of proteins with pH-dependent magnetic nanoadsorbents  

NASA Astrophysics Data System (ADS)

Two kinds of unique pH-dependent magnetic nanoadsorbents based on silica coated magnetic nanoparticles (SMNPs) and amino-silica coated magnetic nanoparticles (ASMNPs) have been exploited for selective separation of proteins. With different isoelectric points, silica coated magnetic nanoadsorbents (SMNAs) and amino-silica coated magnetic nanoadsorbents (ASMNAs) can respectively adsorb proteins with different charges. The interactions between proteins and magnetic nanoadsorbents changed with the solution pH. Thus, the adsorption or desorption between proteins and magnetic nanoadsorbents can be controlled by changing the solution pH according to the charge of the proteins. And the magnetic nanoadsorbents can be separated and recycled simply with a magnet. As model adsorbates, Cyt-c and BSA are selectively separated from simple protein mixtures with SMNAs and ASMNAs respectively. Cyt-c was adsorbed on SMNAs at pH 8.0 at 0.160 mg mg-1. And BSA was adsorbed on ASMNAs at pH 5.0 at 0.142 mg mg-1.

He, Xiaoxiao; Chen, Yingjie; Wang, Kemin; Wu, Ping; Gong, Ping; Huo, Hailing

2007-09-01

143

On-chip magnetic separation of superparamagnetic beads for integrated molecular analysis  

PubMed Central

We have demonstrated a postprocessed complementary metal oxide semiconductor (CMOS) integrated circuit (IC) capable of on-chip magnetic separation, i.e., removing via magnetic forces the nonspecifically bound magnetic beads from the detection area on the surface of the chip. Initially, 4.5 ?m wide superparamagnetic beads sedimenting out of solution due to gravity were attracted to the detection area by a magnetic concentration force generated by flowing current through a conductor embedded in the IC. After sedimentation, the magnetic beads that did not bind strongly to the functionalized surface of the IC through a specific biochemical complex were removed by a magnetic separation force generated by flowing current through another conductor placed laterally to the detection area. As the spherical bead pivoted on the surface of the chip, the lateral magnetic force was further amplified by mechanical leveraging, and 50 mA of current flowing through the separation conductor placed 18 ?m away from the bead resulted in 7.5 pN of tensile force on the biomolecular tether immobilizing the bead. This force proved high enough to break nonspecific interactions while leaving specific antibody-antigen bonds intact. A sandwich capture immunoassay on purified human immunoglobulin G showed strong correlation with a control enzyme linked immunosorbent assay and a detection limit of 10 ng?ml or 70 pM. The beads bound to the detection area after on-chip magnetic separation were detected optically. To implement a fully integrated molecular diagnostics platform, the on-chip magnetic separation functionality presented in this work can be readily combine with state-of-the art CMOS-based magnetic bead detection technology.

Florescu, Octavian; Wang, Kevan; Au, Patrick; Tang, Jimmy; Harris, Eva; Beatty, P. Robert; Boser, Bernhard E.

2010-01-01

144

On-chip magnetic separation of superparamagnetic beads for integrated molecular analysis  

NASA Astrophysics Data System (ADS)

We have demonstrated a postprocessed complementary metal oxide semiconductor (CMOS) integrated circuit (IC) capable of on-chip magnetic separation, i.e., removing via magnetic forces the nonspecifically bound magnetic beads from the detection area on the surface of the chip. Initially, 4.5 ?m wide superparamagnetic beads sedimenting out of solution due to gravity were attracted to the detection area by a magnetic concentration force generated by flowing current through a conductor embedded in the IC. After sedimentation, the magnetic beads that did not bind strongly to the functionalized surface of the IC through a specific biochemical complex were removed by a magnetic separation force generated by flowing current through another conductor placed laterally to the detection area. As the spherical bead pivoted on the surface of the chip, the lateral magnetic force was further amplified by mechanical leveraging, and 50 mA of current flowing through the separation conductor placed 18 ?m away from the bead resulted in 7.5 pN of tensile force on the biomolecular tether immobilizing the bead. This force proved high enough to break nonspecific interactions while leaving specific antibody-antigen bonds intact. A sandwich capture immunoassay on purified human immunoglobulin G showed strong correlation with a control enzyme linked immunosorbent assay and a detection limit of 10 ng/ml or 70 pM. The beads bound to the detection area after on-chip magnetic separation were detected optically. To implement a fully integrated molecular diagnostics platform, the on-chip magnetic separation functionality presented in this work can be readily combine with state-of-the art CMOS-based magnetic bead detection technology.

Florescu, Octavian; Wang, Kevan; Au, Patrick; Tang, Jimmy; Harris, Eva; Beatty, P. Robert; Boser, Bernhard E.

2010-03-01

145

Separation of topographic features from magnetic force images using capacitive coupling effect.  

PubMed

Separation of topographic features from magnetic images has been an issue for the past two decades in magnetic force microscopy (MFM). The frequent pickups of the topographic features are interpreted as transitions of the tip between bistable states of the tip-sample assembly in the noncontact and tapping regions. MFM using electrostatic force modulation demonstrates the separation of the topographic features from the magnetic images by removing the tapping state from the bistable states through the introduction of a capacitive coupling. PMID:19256648

Kim, Byung I

2009-02-01

146

Cr-polluted soil studied by high gradient magnetic separation and electron probe  

SciTech Connect

An Fe-rich soil from the site of a former leather tannery, heavily polluted with Cr, was studied using a combination of wet chemical analysis, high gradient magnetic separation (HGMS), and electron probe microanalysis (EPMA). It is demonstrated that such a combination is a powerful tool for the characterization of polluted soils, especially in cases where the pollution is present as discrete particles. Both EPMA and magnetic separation data indicated that the Cr pollution was present as a hydrous Cr-oxide phase. The Cr does not correlate with the Fe minerals, most likely as a result of the initial high Cr concentrations in the soil, which lead to precipitation of separate hydrous Cr-oxide minerals and Fe minerals. The Cr-containing material is present as (layered) aggregates, which are formed around larger quartz grains or around very small other particles that served as precipitation nuclei. Magnetic separation tests show that the Cr pollution can largely be removed by HGMS.

Rikers, R.A.; Voncken, J.H.L.; Dalmijn, W.L. [Delft Univ. of Technology (Netherlands)

1998-12-01

147

Non-locality of energy separating transformations for Dirac electrons in a magnetic field  

NASA Astrophysics Data System (ADS)

We investigate a non-locality of Moss-Okninski transformation (MOT) used to separate positive and negative energy states in the 3+1 Dirac equation for relativistic electrons in the presence of a magnetic field. Properties of functional kernels generated by the MOT are analyzed and kernel non-localities are characterized by calculating their second moments parallel and perpendicular to the magnetic field. Transformed functions are described and investigated by computing their variances. It is shown that the non-locality of the energy-separating transformation in the direction parallel to the magnetic field is characterized by the Compton wavelength ?c = ?/mc. In the plane transverse to the magnetic field, the non-locality depends both on magnetic radius L = (?/eB)1/2 and ?c. The non-locality of MOT for the 2+1 Dirac equation is also considered.

Rusin, Tomasz M.; Zawadzki, Wlodek

2012-08-01

148

Study on Treatment of Printing and Dyeing Wastewater by Magnetic Seed Coagulation--High Gradient Magnetic Separation  

Microsoft Academic Search

Treatment of printing and dyeing wastewater by the device of high gradient magnetic separation (HGMS) developed by author was tested. The results showed that printing and dyeing wastewater contained varied chemical composition and whose initial concentration of chromaticity and COD were 800 and 565mg\\/L respectively can be well cleaned by Fenton oxidation—magnetic seed coagulation— HGMS. The removal rate of chromaticity

Chen Wen-song; Lin Hua-shi; Zhang Shuo-feng

2011-01-01

149

Magnetically assisted chemical separation (MACS) process: Preparation and optimization of particles for removal of transuranic elements  

SciTech Connect

The Magnetically Assisted Chemical Separation (MACS) process combines the selectivity afforded by solvent extractants with magnetic separation by using specially coated magnetic particles to provide a more efficient chemical separation of transuranic (TRU) elements, other radionuclides, and heavy metals from waste streams. Development of the MACS process uses chemical and physical techniques to elucidate the properties of particle coatings and the extent of radiolytic and chemical damage to the particles, and to optimize the stages of loading, extraction, and particle regeneration. This report describes the development of a separation process for TRU elements from various high-level waste streams. Polymer-coated ferromagnetic particles with an adsorbed layer of octyl(phenyl)-N,N-diisobutylcarbamoylmethylphosphine oxide (CMPO) diluted with tributyl phosphate (TBP) were evaluated for use in the separation and recovery of americium and plutonium from nuclear waste solutions. Due to their chemical nature, these extractants selectively complex americium and plutonium contaminants onto the particles, which can then be recovered from the solution by using a magnet. The partition coefficients were larger than those expected based on liquid[liquid extractions, and the extraction proceeded with rapid kinetics. Extractants were stripped from the particles with alcohols and 400-fold volume reductions were achieved. Particles were more sensitive to acid hydrolysis than to radiolysis. Overall, the optimization of a suitable NMCS particle for TRU separation was achieved under simulant conditions, and a MACS unit is currently being designed for an in-lab demonstration.

Nunez, L.; Kaminski, M.; Bradley, C.; Buchholz, B.A.; Aase, S.B.; Tuazon, H.E.; Vandegrift, G.F. [Argonne National Lab., IL (United States); Landsberger, S. [Univ. of Illinois, Urbana, IL (United States)

1995-05-01

150

Evaluation of Cyanex 923-coated magnetic particles for the extraction and separation of lanthanides and actinides from nuclear waste streams  

Microsoft Academic Search

In the magnetically assisted chemical separation (MACS) process, tiny ferromagnetic particles coated with solvent extractant are used to selectively separate radionuclides and hazardous metals from aqueous waste streams. The contaminant-loaded particles are then recovered from the waste solutions using a magnetic field. The contaminants attached to the magnetic particles are subsequently removed using a small volume of stripping agent. In

B. S. Shaibu; M. L. P. Reddy; A. Bhattacharyya; V. K. Manchanda

2006-01-01

151

Fast separation of bromelain by polyacrylic acid-bound iron oxide magnetic nanoparticles  

Microsoft Academic Search

The adsorption of bromelain from an aqueous solution by polyacrylic acid (PAA)-bound iron oxide magnetic nanoparticles was studied. The magnetic composite nanoparticles were shown to be efficient for the separation of bromelain. Except at pH 0.6M. The adsorption behaviour followed the Langmuir isotherm with a maximum adsorption amount of 0.476mg\\/mg and a Langmuir adsorption equilibrium constant of 58.4ml\\/mg at pH

Dong-Hwang Chen; Shih-Hung Huang

2004-01-01

152

Photocatalytic degradation of dyes on a magnetically separated photocatalyst under visible and UV irradiation  

Microsoft Academic Search

A novel kind of magnetically separable photocatalyst of TiO2\\/SiO2\\/?-Fe2O3 (TSF) is prepared. Scanning tunnel microscope (STM) and X-ray diffractometer (XRD) were used to characterize the structure of the photocatalyst. In the TSF photocatalyst, a TiO2 shell is for photocatalysis, a ?-Fe2O3 core as a carrier is for separation by the magnetic field and a SiO2 membrane between the TiO2 shell

Feng Chen; Yinde Xie; Jincai Zhao; Gongxuan Lu

2001-01-01

153

Flow enhanced non-linear magnetophoretic separation of beads based on magnetic susceptibility.  

PubMed

Magnetic separation provides a rapid and efficient means of isolating biomaterials from complex mixtures based on their adsorption on superparamagnetic (SPM) beads. Flow enhanced non-linear magnetophoresis (FNLM) is a high-resolution mode of separation in which hydrodynamic and magnetic fields are controlled with micron resolution to isolate SPM beads with specific physical properties. In this article we demonstrate that a change in the critical frequency of FNLM can be used to identify beads with magnetic susceptibilities between 0.01 and 1.0 with a sensitivity of 0.01 Hz(-1). We derived an analytical expression for the critical frequency that explicitly incorporates the magnetic and non-magnetic composition of a complex to be separated. This expression was then applied to two cases involving the detection and separation of biological targets. This study defines the operating principles of FNLM and highlights the potential for using this technique for multiplexing diagnostic assays and isolating rare cell types. PMID:24061548

Li, Peng; Kilinc, Devrim; Ran, Ying-Fen; Lee, Gil U

2013-10-15

154

Desulfurization and deashing of solvent refined coal (SRC-I) by high gradient magnetic separation techniques  

SciTech Connect

A pilot-scale high gradient magnetic separations (HGMS) system was assembled to investigate the magnetic separation of ash-forming solids and inorganic sulfur from liquefied coal. The liquefied coal studied was a diluted intermediate product obtained from the DOE-sponsored Tacoma SRC-I pilot plant (50 ton/d coal capacity). The magnetic characteristics and particle size distribution of the Tacoma SRC-I liquefied coal were optimized for removal by HGMS. The effect of the following magnetic separator parameters upon deashing the desulfurization of the diluted liquefied coal was considered: matrix packing density, temperature, applied magnetic field, dilution of and residence time of liquefied coal feed, backflushing of saturated separator parameters upon the deashing and desulfurization of the diluted liquefied model which satisfactorily accounts for HGMS performance was developed. The HGMS system was observed to remove over 90% of the ash-forming materials and inorganic sulfur over a wide range of operating conditions. These removals were increased to 97 and 95%, respectively, with residence times greater than 6 min.

Petrakis, L.; Ahner, P.F.; Kiviat, F.E.

1981-01-01

155

High gradient magnetic particle separation in viscous flows by 3D BEM  

NASA Astrophysics Data System (ADS)

The boundary element method was applied to study the motion of magnetic particles in fluid flow under the action of external nonuniform magnetic field. The derived formulation combines the velocity-vorticity resolved Navier-Stokes equations with the Lagrange based particle tracking model, where the one-way coupling with fluid phase was considered. The derived algorithm was used to test a possible design of high gradient magnetic separation in a narrow channel by computing particles trajectories in channel flow under the influence of hydrodynamic and magnetic forces. Magnetic field gradient was obtained by magnetization wires placed outside of the channel. Simulations with varying external magnetic field and flow rate were preformed in order to asses the collection efficiency of the proposed device. We found that the collection efficiency decreases linearly with increasing flow rate. Also, the collection efficiency was found to increase with magnetic field strength only up a saturation point. Furthermore, we found that high collection efficiently is not feasible at high flow velocity and/or at weak magnetic field. Recommendation for optimal choice of external magnetic field and flow rate is discussed.

Ravnik, J.; Hriberšek, M.

2013-04-01

156

Mechanical and Electrical Properties of Cryo-worked Cu  

NASA Astrophysics Data System (ADS)

For manufacturing the magnets of fusion machines pure copper of both high mechanical resistance and electrical conductivity is required. Though high purity copper guarantees high electrical conductivity, its mechanical properties may be not suitable for the applications in tokamaks. In this view, a new procedure developed for obtaining high purity copper with excellent mechanical strength is described in this work. Samples of oxygen free copper (OFC) have been worked by pressing in liquid nitrogen (77 K). It has been verified that the mechanical properties of the worked metal are strongly dependent on the strain rate. Very low strain rates permitted to attain values of tensile yield strength (550 MPa) significantly higher than those obtained by traditional cold-working at room temperature (450 MPa). The electrical conductivity of the cryo-worked Cu decreases with the tensile yield strength even though the hardest samples of tensile yield strength of 550 MPa exhibit still acceptable values of conductivity (about 94 % IACS at room temperature).

Bettinali, Livio; Tosti, Silvano; Pizzuto, Aldo

2013-10-01

157

D0 Cryo System Control System Autodialer  

SciTech Connect

The DO cryogenic system is controlled by a TI565-PLC based control system. This allows the system to be unmanned when in steady state operation. System experts will need to be contacted when system parameters exceed normal operating points and reach alarm setpoints. The labwide FIRUS system provides one alarm monitor and communication link. An autodialer provides a second and more flexible alarm monitor and communication link. The autodialer monitors contact points in the control system and after receiving indication of an alarm accesses a list of experts which it calls until it receives an acknowledgement. There are several manufacturers and distributors of autodialer systems. This EN explains the search process the DO cryo group used to fmd an autodialer system that fit the cryo system's needs and includes information and specs for the unit we chose.

Urbin, J.; /Fermilab

1990-04-17

158

SIRTF cryo-optics technology plan  

NASA Astrophysics Data System (ADS)

A study was undertaken, early in 1992, to determine if a SIRTF class mission could be developed to allow the Observatory to be launched on an Atlas IIAS rather than the Titan IV/Centaur previously planned. The substantial mass reduction required to make that change resulted in a new set of requirements for science and a heightened interest in light weight optics. This paper addresses the rationale and plan for the Atlas SIRTF cryo-optics technology plan.

Norris, David D.

1993-01-01

159

Complex dynamics of self-generated magnetic clusters in phase-separated perovskites  

NASA Astrophysics Data System (ADS)

The linear and non-linear AC magnetic susceptibilities of the perovskite La1-xSrxCoO3, with 0.15?x?0.30, are presented. It is observed that, for x<0.20, a freezing temperature is defined by AC magnetic susceptibility, pointing to a glassy behaviour whose origin is the phase separation of ferromagnetic metallic-like clusters embedded in an insulating matrix. At this temperature, the non-linear magnetic susceptibility shows critical divergence, similar to spin-glasses, although the width of the diverging peak does not compare well with canonical spin-glasses.

Rivas, J.; Mira, J.; Rinaldi, D.; Caciuffo, R.; Señarís Rodríguez, M. A.

2005-07-01

160

Laboratory cryo soft X-ray microscopy.  

PubMed

Lens-based water-window X-ray microscopy allows two- and three-dimensional (2D and 3D) imaging of intact unstained cells in their near-native state with unprecedented contrast and resolution. Cryofixation is essential to avoid radiation damage to the sample. Present cryo X-ray microscopes rely on synchrotron radiation sources, thereby limiting the accessibility for a wider community of biologists. In the present paper we demonstrate water-window cryo X-ray microscopy with a laboratory-source-based arrangement. The microscope relies on a ?=2.48-nm liquid-jet high-brightness laser-plasma source, normal-incidence multilayer condenser optics, 30-nm zone-plate optics, and a cryo sample chamber. We demonstrate 2D imaging of test patterns, and intact unstained yeast, protozoan parasites and mammalian cells. Overview 3D information is obtained by stereo imaging while complete 3D microscopy is provided by full tomographic reconstruction. The laboratory microscope image quality approaches that of the synchrotron microscopes, but with longer exposure times. The experimental image quality is analyzed from a numerical wave-propagation model of the imaging system and a path to reach synchrotron-like exposure times in laboratory microscopy is outlined. PMID:22119891

Hertz, H M; von Hofsten, O; Bertilson, M; Vogt, U; Holmberg, A; Reinspach, J; Martz, D; Selin, M; Christakou, A E; Jerlström-Hultqvist, J; Svärd, S

2011-11-20

161

Multifunctional magnetic-optical nanoparticle probes for simultaneous detection, separation, and thermal ablation of multiple pathogens.  

PubMed

Multifunctional nanoparticles possessing magnetization and near-infrared (NIR) absorption have warranted interest due to their significant applications in magnetic resonance imaging, diagnosis, bioseparation, target delivery, and NIR photothermal ablation. Herein, the site-selective assembly of magnetic nanoparticles onto the ends or ends and sides of gold nanorods with different aspect ratios (ARs) to create multifunctional nanorods decorated with varying numbers of magnetic particles is described for the first time. The resulting hybrid nanoparticles are designated as Fe(3)O(4)-Au(rod)-Fe(3)O(4) nanodumbbells and Fe(3)O(4)-Au(rod) necklacelike constructs with tunable optical and magnetic properties, respectively. These hybrid nanomaterials can be used for multiplex detection and separation because of their tunable magnetic and plasmonic functionality. More specifically, Fe(3)O(4)-Au(rod) necklacelike probes of different ARs are utilized for simultaneous optical detection based on their plasmon properties, magnetic separation, and photokilling of multiple pathogens from a single sample at one time. The combined functionalities of the synthesized probes will open up many exciting opportunities in dual imaging for targeted delivery and photothermal therapy. PMID:19943255

Wang, Chungang; Irudayaraj, Joseph

2010-01-01

162

New High Performance Magnet Structures for Bead Based MolecularSeparation  

SciTech Connect

New High Performance Magnet Structures for Bead Based Molecular Separation David Humphries Lawrence Berkeley National Laboratory, D.O.E. Joint Genome Institute Abstract High performance Hybrid magnetic separation technology is under continuing development at the D.O.E. Joint Genome Institute and Lawrence Berkeley National Laboratory for general laboratory and high throughput automated applications. This technology has broad applicability for molecular separation in genomics, proteomics and other areas. It s applicability ranges from large and small scale microtiter plate and flow separation processes to single molecule DNA manipulation. It is currently an enabling purification technology for very high throughput production sequencing at the D.O.E. Joint Genome Institute. This technology incorporates hybrid magnetic structures that combine linear permanent magnet material and ferromagnetic material to produce significantly higher fields and gradients than those of currently available commercial devices. These structures incorporate ferromagnetic poles that can be easily shaped to produce complex field distributions for specialized applications. The higher maximum fields and strong gradients of the hybrid structures result in greater holding forces on magnetized targets that are being processed as well as faster extraction. Current development versions of these magnet plates have exhibited fields in excess of 1.0 tesla and gradients approaching 1000.0 tesla/meter. Second generation Hybrid magnet plates have now been developed for both 384 and 96-well applications. This technology is currently being made available to industry through the Tech Transfer Department at Lawrence Berkeley National Laboratory. This work was performed under the auspices of the US Department of Energy's Office of Science, Biological and Environmental Research Program and the by the University of California, Lawrence Livermore National Laboratory under Contract No. W-7405-Eng-48, Lawrence Berkeley National Laboratory under contract No. DE-AC03-6SF00098 and Los Alamos National Laboratory under contract No. W-7405-ENG-36.

Humphries, David

2005-06-01

163

Cryo-electron tomography of cells: connecting structure and function  

PubMed Central

Cryo-electron tomography (cryo-ET) allows the visualization of cellular structures under close-to-life conditions and at molecular resolution. While it is inherently a static approach, yielding structural information about supramolecular organization at a certain time point, it can nevertheless provide insights into function of the structures imaged, in particular, when supplemented by other approaches. Here, we review the use of experimental methods that supplement cryo-ET imaging of whole cells. These include genetic and pharmacological manipulations, as well as correlative light microscopy and cryo-ET. While these methods have mostly been used to detect and identify structures visualized in cryo-ET or to assist the search for a feature of interest, we expect that in the future they will play a more important role in the functional interpretation of cryo-tomograms.

Lucic, Vladan; Leis, Andrew

2008-01-01

164

CryoSat Validation Experiment (CryoVEx) 2011 Radar Penetration Study  

NASA Astrophysics Data System (ADS)

Understanding radar penetration through snow cover on sea ice is essential for sea ice thickness determination using radar altimetry. During the CryoSat Validation Experiment (CryoVEx) in April 2011, we investigated radar penetration into the snow pack. Ground data were collected at three field sites, in the pack ice (85.6 and 83.6N), and on fast ice (82.5N.) Radar data were gathered using the sled-borne UCL Ground Penetrating Radar (GPR), which was deployed for the first time on Arctic sea ice, and the ASIRAS airborne radar altimeter. The ground and airborne radar data are compared to field measurements to investigate how the snow pack properties affect the dominant scattering surface in the radar return echo. In addition we present preliminary comparisons of the airborne radar data with CryoSat-2 and NASA IceBridge airborne altimeters.

Willatt, R. C.; Laxon, S. W.; Haas, C.; Giles, K. A.; Beckers, J.; Davidson, M.; Skourup, H.; Studinger, M.; Cullen, R.; Panzer, B.; Leuschen, C.

2011-12-01

165

Heavy Medium Recovery in Coal Washing by Continuous High Gradient Magnetic Separation. Final Report.  

National Technical Information Service (NTIS)

We have adapted high grade magnetic separation (HGMS) for magnetite recovery because of its insensitivity to coal/magnetite ratio and slurry density and its ability to capture fine magnetite at high velocity. An open vertical matrix able to capture 10 mu ...

D. R. Kelland

1983-01-01

166

High efficiency protein separation with organosilane assembled silica coated magnetic nanoparticles  

NASA Astrophysics Data System (ADS)

This work describes the development of high efficiency protein separation with functionalized organosilanes on the surface of silica coated magnetic nanoparticles. The magnetic nanoparticles were synthesized with average particle size of 9 nm and silica coated magnetic nanoparticles were obtained by controlling the coating thicknesses on magnetic nanoparticles. The silica coating thickness could be uniformly sized with a diameter of 10 40 nm by a sol gel approach. The surface modification was performed with four kinds of functionalized organosilanes such as carboxyl, aldehyde, amine, and thiol groups. The protein separation work with organosilane assembled silica coated magnetic nanoparticles was achieved for model proteins such as bovine serum albumin (BSA) and lysozyme (LSZ) at different pH conditions. Among the various functionalities, the thiol group showed good separation efficiency due to the change of electrostatic interactions and protein conformational structure. The adsorption efficiency of BSA and LSZ was up to 74% and 90% corresponding pH 4.65 and pH 11.

Chang, Jeong Ho; Kang, Ki Ho; Choi, Jinsub; Jeong, Young Keun

2008-10-01

167

Magnetic properties and microstructures of iron oxide@mesoporous silica core-shell composite for applications in magnetic dye separation  

NASA Astrophysics Data System (ADS)

In this report, hollow mesoporous silica (HMS) and iron oxide-hollow mesoporous silica (FexOy@HMS) core-shell composite were prepared by a one-step facile fabrication method. Transmission electron microscopy, X-ray diffraction, N2 adsorption-desorption isotherms, and vibrating sample magnetometer were used to characterize the morphology, microstructure, and magnetic properties of the HMS and core-shell composite. The magnetic separability of FexOy@HMS core-shell composite was tested in Rhodamine B (Rh.B) dye solution. The results indicate that the core-shell composite can absorb Rh.B dyes molecules effectively up to 90.1%.

Hao, Weichang; Xi, Yang; Hu, Jingwei; Wang, Tianmin; Du, Y.; Wang, X. L.

2012-04-01

168

Superconducting open-gradient magnetic separation for the pretreatment of radioactive or mixed waste vitrification feeds. 1998 annual progress report  

SciTech Connect

'The objective is to reduce the volume and cost of high-level waste glass produced during US DOE remediation activities by demonstrating that magnetic separation can separate crystalline, amorphous, and colloidal constituents in vitrification feed streams known to be deleterious to the production of borosilicate glass. Magnetic separation will add neither chemicals nor generate secondary waste streams. The project includes the systematic study of magnetic interactions of waste constituents under controlled physical and chemical conditions (e.g., hydration, oxidation, temperature) to identify mechanisms that control the magnetic properties. Partitioning of radionuclides to determine their sorption mechanisms is also being studied. The identification of fundamental magnetic properties within the microscopic chemical environment in combination with hydrodynamic and electrodynamic models provides insights into the design of a system for optimal separation. Following this, experimental studies using superconducting open-gradient magnetic separation (OGMS) will be conducted to validate its effectiveness as a pretreatment technique.'

Doctor, R.D.; Nunez, L. [Argonne National Lab., IL (US); Crawford, C. [Westinghouse Savannah River Co., Aiken, SC (US); Ritter, J. [Univ. of South Carolina, Columbia, SC (US); Landsberger, S. [Univ. of Texas, Austin, TX (US)

1998-06-01

169

Magnetic materials as sorbents for metal/metalloid preconcentration and/or separation. A review.  

PubMed

The use of magnetic materials in solid phase extraction has received considerable attention in recent years taking into account many advantages arising from the inherent characteristics of magnetic particles. Magnetic solid phase extraction (MSPE) methodology overcomes problems such as column packing and phase separation, which can be easily performed by applying an external magnetic field. The use of magnetic particles in automatic systems is growing over the last few years making the on-line operation of MSPE a promising technique in the frame of green chemistry. This article aims to provide all recent progress in the research of novel magnetic materials as sorbents for metal preconcentration and determination coupled with different detection systems as well as their implementation in sequential injection and microfluidic systems. In addition, a description of preparation, characterization as well as applications of various types of magnetic materials, either with organic or inorganic coating of the magnetic core, is presented. Concluding remarks and future trends are also commented. PMID:23856225

Giakisikli, Georgia; Anthemidis, Aristidis N

2013-04-29

170

Measurement of the adhesion force between particles for high gradient magnetic separation of pneumatic conveyed powder products  

NASA Astrophysics Data System (ADS)

In the industrial plants such as foods, medicines or industrial materials, there are big amount of issues on contamination by metallic wear debris originated from pipes of manufacturing lines. In this study, we developed a high gradient magnetic separation system (HGMS) under the dry process by using superconducting magnet to remove the ferromagnetic particles. One of the major problems of dry HGMS systems is, however, the blockage of magnetic filter caused by particle coagulation or deposition. In order to actualize the magnetic separation without blockage, we introduced pneumatic conveyance system as a new method to feed the powder. It is important to increase the drag force acting on the sufficiently dispersed particles, which require strong magnetic fields. To generate the strong magnetic fields, HGMS technique was examined which consists of a magnetic filter and a superconducting solenoid magnet.As a result of the magnetic separation experiment, it was shown that the separation efficiency changes due to the difference of the cohesive property of the particles. On the basis of the result, the adhesion force which acts between the ferromagnetic particles and the medium particles used for the magnetic separation was measured by Atomic Force Microscope (AFM), and cohesion of particles was studied from the aspect of interparticle interaction. We assessed a suitable flow velocity for magnetic separation according to the cohesive property of each particle based on the result.

Senkawa, K.; Nakai, Y.; Mishima, F.; Akiyama, Y.; Nishijima, S.

2011-11-01

171

Assessment of crystalline disorder in cryo-milled samples of indomethacin using atomic pair-wise distribution functions.  

PubMed

The aim of this study was to investigate the usefulness of the atomic pair-wise distribution function (PDF) to detect the extension of disorder/amorphousness induced into a crystalline drug using a cryo-milling technique, and to determine the optimal milling times to achieve amorphisation. The PDF analysis was performed on samples of indomethacin obtained by cryogenic ball milling (cryo-milling) for different periods of time. X-ray powder diffraction (XRPD), differential scanning calorimetry (DSC), polarised light microscopy (PLM) and solid state nuclear magnetic resonances (ss-NMR) were also used to analyse the cryo-milled samples. The high similarity between the ?-indomethacin cryogenic ball milled samples and the crude ?-indomethacin indicated that milled samples retained residual order of the ?-form. The PDF analysis encompassed the capability of achieving a correlation with the physical properties determined from DSC, ss-NMR and stability experiments. Multivariate data analysis (MVDA) was used to visualize the differences in the PDF and XRPD data. The MVDA approach revealed that PDF is more efficient in assessing the introduced degree of disorder in ?-indomethacin after cryo-milling than MVDA of the corresponding XRPD diffractograms. The PDF analysis was able to determine the optimal cryo-milling time that facilitated the highest degree of disorder in the samples. Therefore, it is concluded that the PDF technique may be used as a complementary tool to other solid state methods and that further investigations are warranted to elucidate the capabilities of this technique. PMID:21182911

Bøtker, Johan P; Karmwar, Pranav; Strachan, Clare J; Cornett, Claus; Tian, Fang; Zujovic, Zoran; Rantanen, Jukka; Rades, Thomas

2010-12-21

172

High-gradient magnetic separation in blood and bone marrow processing  

NASA Astrophysics Data System (ADS)

High-gradient magnetic separation (HGMS) has been succesful in capturing red blood cells from whole blood. This is due to the paramagnetic property of the haemoglobin contained in red blood cells when it is in the deoxygenated state. The captured red blood cells and the processed white blood cells and platelets appear to be functionally undamaged by separation. The capture depends on field gradient, flow rate, dilution of the blood, size of filter and a number of other factors. Malarial parasite-containing red cells have been captured using this technique and elsewhere lymphocyte/red cell rosettes have been retained in the filter of a system using a field gradient produced by a superconducting magnet. The ex vivo processing of human bone marrow is currently under study. Removal of targetted cells from bone marrow, such as tumour cells or T-lymphocytes prior to reinfusion is currently practiced. Positive cell rescue, however, is not practicable as the present techniques mostly damage the targetted cells. We are applying high-gradient magnetic separation, using an antibody complex linked to the surface of red blood cells, which should recognise target cells within bone marrow. The whole complex is then liable to retention in a sufficiently high-gradient magnetic field and the target cell made available by red-blood-cell lysis.

Roath, S.; Smith, A. Richards; Watson, J. H. P.

1990-04-01

173

Separating Effect of a Novel Combined Magnetic Field on Inclusions in Molten Aluminum Alloy  

NASA Astrophysics Data System (ADS)

The feasibility and effectiveness of a novel combined magnetic field (CMF) on the removal of inclusions with a density smaller than the surrounding melt were investigated. The experiment of the separating effect of CMF was conducted on a laboratory-scale apparatus by the simultaneous application of a rotating magnetic field (RMF) and a downward traveling magnetic field (TMF). Primary silicon particles precipitating from the solidification process of Al-Si-Cu alloy were regarded as the inclusions in a molten aluminum alloy. It was found that a CMF consisting of both a RMF and a downward TMF was able to separate silicon particles from the molten Al-Si-Cu alloy by making these particles migrate vertically toward the upper part of the samples. Compared with downward TMF or RMF, CMF improved the separating effectiveness substantially. It was proposed that this type of CMF was approved to be highly effective at eliminating the inclusions with a density smaller than the surrounding molten alloy. A tentative mechanism for the high separating effect of CMF was discussed.

He, Yanjie; Li, Qiulin; Liu, Wei

2012-10-01

174

Microchip electrophoresis coupled with on-line magnetic separation and chemiluminescence detection for multiplexed immunoassay.  

PubMed

A facile and universal strategy for multiplexed immunoassay is proposed. The strategy is based on microchip electrophoresis (MCE) coupled with on-line magnetic separation and chemiluminescence (CL) detection. The system consisted of a microchip, an electromagnet, and a photomultiplier. The realization of multiplexed immunoassay protocol involves sampling magnetic nanoparticles (MNPs) labeled antibodies, N-(4-aminobutyl)-N-ethyl-isoluminol (ABEI) labeled antigens and free antigens in the precolumn reactor, on-line immunoreaction, capturing the MNPs-immunocomplexes, and the separation of unconjugated ABEI-labeled antigens. After on-line magnetic separation, the free ABEI-labeled antigens were transported into the separation channel, and mixed with hydrogen peroxide (H(2) O(2) ) in the presence of horseradish peroxidase in the postcolumn reactor, and producing CL emission. Using this arrangement, multiple analytes could be measured simultaneously by performing the technical operations for a single assay. As a proof-of-concept, the multiplexed immunoassay was evaluated for the simultaneous determination of five model analytes (i.e. hydrocortisone, corticosterone, digoxin, testosterone, and estriol). The results exhibited excellent precision and sensitivity, the relative standard deviations for nine times detection were lower than 4.7% for all the five components, and the detection limits of five analytes were in the range of 3.6-4.9 nM. The MCE system was validated using two human serum-based control samples containing five analytes. PMID:22539323

Huang, Yong; Zhao, Shulin; Shi, Ming; Liu, Jinwen; Liang, Hong

2012-04-01

175

Removal and recycle of phosphate from treated water of sewage plants with zirconium ferrite adsorbent by high gradient magnetic separation  

Microsoft Academic Search

Zirconium ferrite particles are good adsorbent for phosphate ions. Magnetic separation characteristics for removal of phosphate from treated water of sewage plants with the adsorbent have been studied to prevent eutrophication of semi-enclosed bay, e.g. the bay of Tokyo. Based on the adsorption for the phosphate ions and ferromagnetic properties of the zirconium ferrite adsorbent, high gradient magnetic separation characteristics

D. Ito; K. Nishimura; O. Miura

2009-01-01

176

Haloing in bimodal magnetic colloids: the role of field-induced phase separation.  

PubMed

If a suspension of magnetic micrometer-sized and nanosized particles is subjected to a homogeneous magnetic field, the nanoparticles are attracted to the microparticles and form thick anisotropic halos (clouds) around them. Such clouds can hinder the approach of microparticles and result in effective repulsion between them [M. T. López-López, A. Yu. Zubarev, and G. Bossis, Soft Matter 6, 4346 (2010)]. In this paper, we present detailed experimental and theoretical studies of nanoparticle concentration profiles and of the equilibrium shapes of nanoparticle clouds around a single magnetized microsphere, taking into account interactions between nanoparticles. We show that at a strong enough magnetic field, the ensemble of nanoparticles experiences a gas-liquid phase transition such that a dense liquid phase is condensed around the magnetic poles of a microsphere while a dilute gas phase occupies the rest of the suspension volume. Nanoparticle accumulation around a microsphere is governed by two dimensionless parameters--the initial nanoparticle concentration (?(0)) and the magnetic-to-thermal energy ratio (?)--and the three accumulation regimes are mapped onto a ?-?(0) phase diagram. Our local thermodynamic equilibrium approach gives a semiquantitative agreement with the experiments on the equilibrium shapes of nanoparticle clouds. The results of this work could be useful for the development of the bimodal magnetorheological fluids and of the magnetic separation technologies used in bioanalysis and water purification systems. PMID:23005414

Magnet, C; Kuzhir, P; Bossis, G; Meunier, A; Suloeva, L; Zubarev, A

2012-07-13

177

Haloing in bimodal magnetic colloids: The role of field-induced phase separation  

NASA Astrophysics Data System (ADS)

If a suspension of magnetic micrometer-sized and nanosized particles is subjected to a homogeneous magnetic field, the nanoparticles are attracted to the microparticles and form thick anisotropic halos (clouds) around them. Such clouds can hinder the approach of microparticles and result in effective repulsion between them [M. T. López-López, A. Yu. Zubarev, and G. Bossis, Soft Matter10.1039/c0sm00261e 6, 4346 (2010)]. In this paper, we present detailed experimental and theoretical studies of nanoparticle concentration profiles and of the equilibrium shapes of nanoparticle clouds around a single magnetized microsphere, taking into account interactions between nanoparticles. We show that at a strong enough magnetic field, the ensemble of nanoparticles experiences a gas-liquid phase transition such that a dense liquid phase is condensed around the magnetic poles of a microsphere while a dilute gas phase occupies the rest of the suspension volume. Nanoparticle accumulation around a microsphere is governed by two dimensionless parameters—the initial nanoparticle concentration (?0) and the magnetic-to-thermal energy ratio (?)—and the three accumulation regimes are mapped onto a ?-?0 phase diagram. Our local thermodynamic equilibrium approach gives a semiquantitative agreement with the experiments on the equilibrium shapes of nanoparticle clouds. The results of this work could be useful for the development of the bimodal magnetorheological fluids and of the magnetic separation technologies used in bioanalysis and water purification systems.

Magnet, C.; Kuzhir, P.; Bossis, G.; Meunier, A.; Suloeva, L.; Zubarev, A.

2012-07-01

178

Quantitative separation of bacteria in saline solution using lanthanide Er(III) and a magnetic field.  

PubMed

A trivalent lanthanide ion, erbium (Er3+), has been used in combination with a magnetic separation technique to isolate seven bacterial species from suspensions in 0.9% saline. Erbium has an exceptionally high atomic magnetic moment of 9.3 Bohr magnetons, and following addition as ErCl3 (final concentration 5 mM) to bacterial suspensions, it imparts the magnetic moment to the bacterial cells by ionic binding to the cell surface. Strains of Escherichia coli, Klebsiella pneumoniae, Proteus mirabilis, Pseudomonas aeruginosa, Staphylococcus epidermidis, Staphylococcus saprophyticus and Enterococcus faecalis were obtained from the Quality Control Depository of The Cleveland Clinic Foundation, Cleveland, Ohio, USA as suspensions in 0.9% NaCl, in concentrations ranging from 10(2) to 10(8) c.f.u. ml-1. Bacteria were separated from solution inside a capillary flow cell exposed to a highly non-homogeneous magnetic field (maximum field intensity was 0.4 T) and quantified by a light scattering method. The quantity of cellular deposition in the magnetic field was correlated with the initial concentration of cells in the suspension, expressed in c.f.u. ml-1, and sample volume (1.5 and 3.0 ml), sample pH (prior to ErCl3 addition), affinity to Gram stain (negative vs positive) and species.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:1556557

Zborowski, M; Malchesky, P S; Jan, T F; Hall, G S

1992-01-01

179

Review and evaluation of extractants for strontium removal using magnetically assisted chemical separation  

SciTech Connect

A literature review on extractants for strontium removal was initially performed at Northern Illinois University to assess their potential in magnetically assisted chemical separation. A series of potential strontium extractants was systematically evaluated there using radioanalytical methods. Initial experiments were designed to test the uptake of strontium from nitric acid using several samples of magnetic extractant particles that were coated with various crown ether ligands. High partition coefficient (K{sub d}) values for stimulant tank waste were obtained. Further studies demonstrated that the large partitioning was due to uncoated particles.

Bauer, C.B.; Rogers, R.D. [Northern Illinois Univ., De Kalb, IL (United States). Dept. of Chemistry; Nunez, L.; Ziemer, M.D.; Pleune, T.T.; Vandegrift, G.F. [Argonne National Lab., IL (United States)

1995-11-01

180

Separation of true fat and water images by correcting magnetic field inhomogeneity in situ.  

PubMed

Dixon's method of chemical shift imaging of a two-component system is modified and extended without requiring additional imaging time. The modified method allows one to obtain truly segregated fat and water images of animal tissues. This is accomplished by acquiring additional image data from which information about in situ magnetic field inhomogeneity and bulk magnetic susceptibility can be derived. Applications to various anatomic sections of the normal human body are illustrated. The method is compared with the standard Dixon technique of chemical shift image separation. PMID:3704157

Yeung, H N; Kormos, D W

1986-06-01

181

X-25 Cryo-ready In-vacuum Undulator at the NSLS  

SciTech Connect

The existing 15-year-old hybrid wiggler at the NSLS has been replaced by a state-of-the-art, cryo-ready in-vacuum undulator optimized for a dedicated macromolecular crystallography program. The device is a 1m long, 18mm period, hybrid PM-type with a minimum operating gap of 5.6mm, and has provision for cryo-cooling to 150K. Unlike the original SPring-8 cryo-PM undulator proposal, we use a new high-remanence, high-temperature grade of NdFeB (NEOMAX 42AH with Br=1.3T and Hcj=24 kOe) that can be baked to 100 deg. C to be UHV-ready in case of cooling system failure. A novel optical gap measurement system using a LED-based product ensures gap accuracy of {+-}2 micro meter. A friction stir welding technique is used for the first time in an accelerator UHV device to minimize stress and deformation of the magnet arrays due to temperature gradients. This paper describes design issues of the device and other considerations such as magnetic measurement at low temperature.

Tanabe, Toshiya; Ablett, James; Berman, Lonny; Harder, David A.; Hulbert, Steve; Lehecka, Mike; Rakowsky, George; Skaritka, John [National Synchrotron Light Source, Brookhaven National Laboratory, Upton, NY 11973 (United States); Deyhim, Alex; Johnson, Eric; Kulesza, Joe; Waterman, Dave [Advanced Design Consulting, U.S.A, Inc., 126 Ridge Rd, PO Box 187, Lansing, NY 14882 (United States)

2007-01-19

182

Cryo-Electron Tomography for Structural Characterization of Macromolecular Complexes  

PubMed Central

Cryo-electron tomography (cryo-ET) is an emerging 3-D reconstruction technology that combines the principles of tomographic 3-D reconstruction with the unmatched structural preservation of biological material embedded in vitreous ice. Cryo-ET is particularly suited to investigating cell-biological samples and large macromolecular structures that are too polymorphic to be reconstructed by classical averaging-based 3-D reconstruction procedures. This unit aims to make cryo-ET accessible to newcomers and discusses the specialized equipment required, as well as the relevant advantages and hurdles associated with sample preparation by vitrification and cryo-ET. Protocols describe specimen preparation, data recording and 3-D data reconstruction for cryo-ET, with a special focus on macromolecular complexes. A step-by-step procedure for specimen vitrification by plunge freezing is provided, followed by the general practicalities of tilt-series acquisition for cryo-ET, including advice on how to select an area appropriate for acquiring a tilt series. A brief introduction to the underlying computational reconstruction principles applied in tomography is described, along with instructions for reconstructing a tomogram from cryo-tilt series data. Finally, a method is detailed for extracting small subvolumes containing identical macromolecular structures from tomograms for alignment and averaging as a means to increase the signal-to-noise ratio and eliminate missing wedge effects inherent in tomographic reconstructions.

Cope, Julia; Heumann, John; Hoenger, Andreas

2011-01-01

183

A continuous, hybrid field-gradient device for magnetic colloid-based separations  

NASA Astrophysics Data System (ADS)

A fully continuous, hybrid field-gradient device is developed for colloidal magnetic affinity separation. The device consists of a 1.0cm internal diameter 1.2m long, axially rotating horizontal glass chamber, with four repeating magnetic units distributed axially along the tube. Each magnetic unit consists of a stationary alternating-current solenoid that surrounds the chamber, followed by a direct current flowing, computer-controlled electromagnet, placed at a distance of 4.0cm from the end of the solenoid. The alternating-current-carrying solenoids impart translational and rotary oscillations to the magnetic particles, enhancing mixing. The computer-controlled electromagnets draw the magnetic particles to the chamber walls, and increase their residence time in the chamber. By manipulating the on-off cycle for these electromagnets, the exiting solution can be switched between one that contains a negligible concentration of target-bound magnetic particles and one that has a high concentration of the target, without interrupting the feed. The operation of this device is demonstrated for the removal of cadmium ions from a cadmium sulfate solution. 1-10?m diameter anion-exchange-resin-coated magnetic particles at a concentration of 0.5mg particles/ml were used as the mobile solid support. The feed consisted of a 10.0mg/l cadmium sulfate solution, at a flow rate of 25ml/min. The device was operated as a three-stage cross-current cascade. For this system, 45%, 58% and 63% of the entering cadmium ions are removed at each stage, respectively, with stage efficiencies that vary between 57% and 65%. Thus, more than 90% of the entering cadmium ions are removed. While this device has been demonstrated for metal ion removal from an aqueous feed, it can potentially be applied to several other affinity-based separations.

Ghebremeskel, Alazar N.; Bose, Arijit

2003-04-01

184

High efficiency X-band magnetically insulated line oscillator with a separate cathode  

NASA Astrophysics Data System (ADS)

An X-band magnetically insulated line oscillator (MILO) with a separate cathode has been proposed in order to improve microwave output characteristics. The separate cathode consists of three parts with gradually decreased radii, which are divided by two deep grooves, and only partial cathode surfaces are allowed to emit electrons. In particle-in-cell simulation, high-power microwave with a power of 6.9 GW, frequency of 9.26 GHz, and efficiency of 20.6% is generated, compared with that of 12.2% obtained in a conventional cathode X-band MILO, and the power ratio of the output transverse-electromagnetic mode to transverse-magnetic (TM01) mode is increased from 4 to 27.

Xiao, Renzhen; Song, Wei; Song, Zhimin; Sun, Jun; Shao, Hao; Chen, Changhua

2010-04-01

185

Magnetic separation of malaria-infected red blood cells in various developmental stages.  

PubMed

Malaria is a serious disease that threatens the public health, especially in developing countries. Various methods have been developed to separate malaria-infected red blood cells (i-RBCs) from blood samples for clinical diagnosis and biological and epidemiological research. In this study, we propose a simple and label-free method for separating not only late-stage but also early-stage i-RBCs on the basis of their paramagnetic characteristics due to the malaria byproduct, hemozoin, by using a magnetic field gradient. A polydimethylsiloxane (PDMS) microfluidic channel was fabricated and integrated with a ferromagnetic wire fixed on a glass slide. To evaluate the performance of the microfluidic device containing the ferromagnetic wire, lateral displacement of NaNO2-treated RBCs, which also have paramagnetic characteristics, was observed at various flow rates. The results showed excellent agreement with theoretically predicted values. The same device was applied to separate i-RBCs. Late-stage i-RBCs (trophozoites and schizonts), which contain optically visible black dots, were separated with a recovery rate of approximately 98.3%. In addition, using an optimal flow rate, early-stage (ring-stage) i-RBCs, which had been difficult to separate because of their low paramagnetic characteristics, were successfully separated with a recovery rate of 73%. The present technique, using permanent magnets and ferromagnetic wire in a microchannel, can effectively separate i-RBCs in various developmental stages so that it could provide a potential tool for studying the invasion mechanism of the malarial parasite, as well as performing antimalarial drug assays. PMID:23815099

Nam, Jeonghun; Huang, Hui; Lim, Hyunjung; Lim, Chaeseung; Shin, Sehyun

2013-07-10

186

Study on the Cytochrome C Separation Based on Silica Coated Magnetic Nanoparticles  

Microsoft Academic Search

A simple and fast method for separation of cytochrome C (Cyt-C) has been reported based on the electrostatic adsorption between silica coated magnetic nanoparticles (SMNPs) and Cyt-C. When the solution pH is above 6.0, but below the isoelectric point of Cyt-C (pi = 10.6), SMNPs possess zeta potential below -30 mV and can electrically adsorb positively charged Cyt-C to form

Yingjie Chen; Xiaoxiao He; Kemin Wang; Ping Wu; Weihong Tan

2007-01-01

187

High-efficiency bioaffinity separation of cells and proteins using novel thermoresponsive biotinylated magnetic nanoparticles  

Microsoft Academic Search

Thermoresponsive magnetic nanoparticles with an upper critical solution temperature (UCST) in aqueous solution were synthesized\\u000a for the first time. Named Therma-Max, the material was synthesized by redox copolymerization of N-acryloyl glycinamide with a monomer form of biotin using methacrylated dextran-magnetite. While the resulting Therma-Max\\u000a was completely dispersed at temperatures above the UCST (18°C) and could not be separated by a

Noriyuki Ohnishi; Hirotaka Furukawa; Hata Hideyuki; Jing-Ming Wang; Chung-Il An; Eiichiro Fukusaki; Kazunori Kataoka; Katsuhiko Ueno; Akihiko Kondo

2006-01-01

188

Dual-template synthesis of magnetically-separable hierarchically-ordered porous carbons by catalytic graphitization  

Microsoft Academic Search

Magnetically-separable hierarchically-ordered porous carbons with graphitic structures (HPC-G) have been directly synthesized by one-pot dual-templating with evaporation-induced self-assembly at calcination temperatures ranging between 600 and 1000°C. Polystyrene latex spheres and triblock copolymer F127 were used as macro- and meso-porous structure-directing agents, while phenol–formaldehyde resins and Ni species were added as the carbon source and graphitization catalyst, respectively. The microstructures in

Chun-hsien Huang; Ruey-an Doong; Dong Gu; Dongyuan Zhao

2011-01-01

189

Selective separation of lambdacyhalothrin by porous/magnetic molecularly imprinted polymers prepared by Pickering emulsion polymerization.  

PubMed

Porous/magnetic molecularly imprinted polymers (PM-MIPs) were prepared by Pickering emulsion polymerization. The reaction was carried out in an oil/water emulsion using magnetic halloysite nanotubes as the stabilizer instead of a toxic surfactant. In the oil phase, the imprinting process was conducted by radical polymerization of functional and cross-linked monomers, and porogen chloroform generated steam under the high reaction temperature, which resulted in some pores decorated with easily accessible molecular binding sites within the as-made PM-MIPs. The characterization demonstrated that the PM-MIPs were porous and magnetic inorganic-polymer composite microparticles with magnetic sensitivity (Ms = 0.7448 emu/g), thermal stability (below 473 K) and magnetic stability (over the pH range of 2.0-8.0). The PM-MIPs were used as a sorbent for the selective binding of lambdacyhalothrin (LC) and rapidly separated under an external magnetic field. The Freundlich isotherm model gave a good fit to the experimental data. The adsorption kinetics of the PM-MIPs was well described by pseudo-second-order kinetics, indicating that the chemical process could be the rate-limiting step in the adsorption of LC. The selective recognition experiments exhibited the outstanding selective adsorption effect of the PM-MIPs for target LC. Moreover, the PM-MIPs regeneration without significant loss in adsorption capacity was demonstrated by at least four repeated cycles. PMID:23894024

Hang, Hui; Li, Chunxiang; Pan, Jianming; Li, Linzi; Dai, Jiangdong; Dai, Xiaohui; Yu, Ping; Feng, Yonghai

2013-08-27

190

Colouring cryo-cooled crystals: online microspectrophotometry  

PubMed Central

X-rays can produce a high concentration of radicals within cryo-cooled macromolecular crystals. Some radicals have large extinction coefficients in the visible (VIS) range of the electromagnetic spectrum, and can be observed optically and spectrally. An online microspectrophotometer with high temporal resolution has been constructed that is capable of measuring UV/VIS absorption spectra (200–1100?nm) during X-ray data collection. The typical X-ray-induced blue colour that is characteristic of a wide range of cryo-conditions has been identified as trapped solvated electrons. Disulphide-containing proteins are shown to form disulphide radicals at millimolar concentrations, with absorption maxima around 400?nm. The solvated electrons and the disulphide radicals seem to have a lifetime in the range of seconds up to minutes at 100?K. The temperature dependence of the kinetics of X-ray-induced radical formation is different for the solvated electrons compared with the disulphide radicals. The online microspectrophotometer provides a technique complementary to X-ray diffraction for analysing and characterizing intermediates and redox states of proteins and enzymes.

McGeehan, John; Ravelli, Raimond B. G.; Murray, James W.; Owen, Robin Leslie; Cipriani, Florent; McSweeney, Sean; Weik, Martin; Garman, Elspeth F.

2009-01-01

191

New monodisperse magnetic polymer microspheres biofunctionalized for enzyme catalysis and bioaffinity separations.  

PubMed

Magnetic macroporous PGMA and PHEMA microspheres containing carboxyl groups are synthesized by multi-step swelling and polymerization followed by precipitation of iron oxide inside the pores. The microspheres are characterized by SEM, IR spectroscopy, AAS, and zeta-potential measurements. Their functional groups enable bioactive ligands of various sizes and chemical structures to couple covalently. The applicability of these monodisperse magnetic microspheres in biospecific catalysis and bioaffinity separation is confirmed by coupling with the enzyme trypsin and huIgG. Trypsin-modified magnetic PGMA-COOH and PHEMA-COOH microspheres are investigated in terms of their enzyme activity, operational and storage stability. The presence of IgG molecules on microspheres is confirmed. PMID:22411761

Horák, Daniel; Ku?erová, Jana; Korecká, Lucie; Jankovi?ová, Barbora; Palar?ík, Ji?í; Mikulášek, Petr; Bílková, Zuzana

2012-03-13

192

Recover vigorous cells of Magnetospirillum magneticum AMB-1 by capillary magnetic separation  

NASA Astrophysics Data System (ADS)

Cultivable magnetotactic bacteria (MTB) in laboratory can provide sufficient samples for molecular microbiological and magnetic studies. However, a cold-stored MTB strain, such as Magnetospirillum magneticum AMB-1, often loses its ability to synthesize magnetosomes and consequently fails to sense the external magnetic field. It is therefore important to quickly recover vigorous bacteria cells that highly capable of magnetosome producing. In this study, a modified capillary magnetic separation system was designed to recover a deteriorating strain of Magnetospirillum magneticum AMB-1 that long-term cold-stored in a refrigerator. The results show that all cells obtained after a 3-cycle treatment were vigorous and had the ability to produce magnetosomes. Moreover, the 3rd-cycle recovered cells were able to form more magnetosome crystals. Compared with the colony formation method, this new method is time-saving, easily operated, and more efficient for recovering vigorous MTB cells.

Li, Jinhua; Ge, Xin; Zhang, Xiaokui; Chen, Guanjun; Pan, Yongxin

2010-07-01

193

Cesium separation from contaminated milk using magnetic particles containing crystalline silicotitantes.  

SciTech Connect

The Chernobyl nuclear reactor disaster in 1986 contaminated vast regions of prime grazing land. Subsequently, milk produced in the region has been contaminated with small amounts of the long-lived fission product cesium-137, and the Ukraine is seeking to deploy a simple separation process that will remove the Cs and preserve the nutritional value of the milk. Tiny magnetic particles containing crystalline silicotitanates (CST) have been manufactured and tested to this end. The results show that partitioning efficiency is optimized with low ratios of particle mass to volume. To achieve 90% Cs decontamination in a single-stage process, <3 g of magnetic CST per l milk is sufficient with a 30-min mixing time. A two-stage process would utilize <0.4 g/l per stage. The modeling of the magnetic CST system described herein can be achieved rather simply which is important for deployment in the affected Ukraine region.

Nunez, L.; Kaminski, M.; Chemical Engineering

2000-11-01

194

The use of multifunctional magnetic mesoporous core/shell heteronanostructures in a biomolecule separation system.  

PubMed

A multifunctional magnetic mesoporous core/shell heteronanostructure (designated as Fe(3)O(4)@NiSiO(3)) has been designed and constructed that combined the capacity of effective protein purification from protein mixture and selective low molecule weight (MW) biomolecule enrichment. The nanoparticle is composed by magnetite nanoparticle with immobilized metal ion surface and solid porous shell which presents a number of important features, such as controllable shell thickness, uniform pore size and excellent magnetism. By taking advantages of the high affinity of Ni(2+) on the shell surface toward His-tagged proteins and the fast response toward an assistant magnet, the heteronanoparticles can be applied to selectively bind to and magnetically separate of His-tagged proteins from a cell lysate of E. coli. Additionally, owing to the homogeneous 3D mesopores on the nickel silicate shell, the heteronanoparticles can selectively capture low MW biomolecules from complex mixture. Significantly, it is expected that this approach can be extended to other biomolecule separation and enrichment systems by changing the immobilized surface and the pore size. PMID:21481453

Liu, Zhen; Li, Meng; Yang, Xinjian; Yin, Meili; Ren, Jinsong; Qu, Xiaogang

2011-04-09

195

A lysozyme and magnetic bead based method of separating intact bacteria.  

PubMed

As a response to environmental stress, bacterial cells can enter a physiological state called viable but noncultivable (VBNC). In this state, bacteria fail to grow on routine bacteriological media. Consequently, standard methods of contamination detection based on bacteria cultivation fail. Although they are not growing, the cells are still alive and are able to reactivate their metabolism. The VBNC state and low bacterial densities are big challenges for cultivation-based pathogen detection in drinking water and the food industry, for example. In this context, a new molecular-biological separation method for bacteria using point-mutated lysozymes immobilised on magnetic beads for separating bacteria is described. The immobilised mutated lysozymes on magnetic beads serve as bait for the specific capture of bacteria from complex matrices or water due to their remaining affinity for bacterial cell wall components. Beads with bacteria can be separated using magnetic racks. To avoid bacterial cell lysis by the lysozymes, the protein was mutated at amino acid position 35, leading to the exchange of the catalytic glutamate for alanine (LysE35A) and glutamine (LysE35Q). As proved by turbidity assay with reference bacteria, the muramidase activity was knocked out. The mutated constructs were expressed by the yeast Pichia pastoris and secreted into expression medium. Protein enrichment and purification were carried out by SO(3)-functionalised nanoscale cationic exchanger particles. For a proof of principle, the proteins were biotinylated and immobilised on streptavidin-functionalised, fluorescence dye-labelled magnetic beads. These constructs were used for the successful capture of Syto9-marked Microccocus luteus cells from cell suspension, as visualised by fluorescence microscopy, which confirmed the success of the strategy. PMID:21574057

Diler, Ebru; Obst, Ursula; Schmitz, Katja; Schwartz, Thomas

2011-05-17

196

THE DETECTION OF NUMEROUS MAGNETIC SEPARATORS IN A THREE-DIMENSIONAL MAGNETOHYDRODYNAMIC MODEL OF SOLAR EMERGING FLUX  

SciTech Connect

Magnetic separators in three-dimensional (3D) magnetic fields are believed to be often associated with locations of magnetic reconnection. In this preliminary study, we investigate this relationship using data from a numerical resistive 3D MHD experiment of a solar flux emergence event. For the first time separators are detected in complex magnetic fields resulting from a 3D resistive MHD model of flux emergence. Two snapshots of the model, taken from different stages of its evolution, are analyzed. Numerous separators are found in both snapshots, and their properties, including their geometry, length, relationship to the magnetic null points, and integrated parallel electric field are studied. The separators reside at the junctions between the emerging flux, the overlying field, and two other flux domains that are newly formed by reconnection. The long separators, which connect clusters of nulls that lie either side of the emerging flux, pass through spatially localized regions of high parallel electric field and correspond to local maxima in integrated parallel electric field. These factors indicate that strong magnetic reconnection takes place along many of the separators, and that separators play a key role during the interaction of emerging and overlying flux.

Parnell, C. E.; Maclean, R. C.; Haynes, A. L., E-mail: clare@mcs.st-and.ac.u [School of Mathematics and Statistics, University of St Andrews, The North Haugh, St Andrews, Fife, KY16 9SS (United Kingdom)

2010-12-20

197

Upgrading of Low-Grade Manganese Ore by Selective Reduction of Iron Oxide and Magnetic Separation  

NASA Astrophysics Data System (ADS)

The utilization of low-grade manganese ores has become necessary due to the intensive mining of high-grade ores for a long time. In this study, calcined ferruginous low-grade manganese ore was selectively reduced by CO, which converted hematite to magnetite, while manganese oxide was reduced to MnO. The iron-rich component was then separated by magnetic separation. The effects of the various reduction parameters such as particle size, reduction time, temperature, and CO content on the efficiency of magnetic separation were studied by single-factor experiments and by a comprehensive full factorial experiment. Under the best experimental conditions tested, the manganese content in the ore increased from around 36 wt pct to more than 44 wt pct, and almost 50 wt pct of iron was removed at a Mn loss of around 5 pct. The results of the full factorial experiments allowed the identification of the significant effects and yielded regression equations for pct Fe removed, Mn/Fe, and pct Mn loss that characterize the efficiency of the upgrading process.

Gao, Yubo; Olivas-Martinez, M.; Sohn, H. Y.; Kim, Hang Goo; Kim, Chan Wook

2012-12-01

198

Three-dimensional modeling of a portable medical device for magnetic separation of particles from biological fluids  

NASA Astrophysics Data System (ADS)

A portable separator has been developed to quantitatively separate blood-borne magnetic spheres in potentially high-flow regimes for the human detoxification purpose. In the separator design, an array of biocompatible capillary tubing and magnetizable wires is immersed in an external magnetic field that is generated by two permanent magnets. The wires are magnetized and the high magnetic field gradient from the magnetized wires helps to collect blood-borne magnetic nano/micro-spheres from the blood flow. In this study, a 3D numerical model was created and the effect of tubing-wire configurations on the capture efficiency of the system was analyzed using COMSOL Multiphysics 3.3®. The results showed that the configuration characterized by bi-directionally alternating wires and tubes was the best design with respect to the four starting configurations. Preliminary in vitro experiments verified the numerical predictions. The results helped us to optimize a prototype portable magnetic separator that is suitable for rapid sequestration of magnetic nano/micro-spheres from the human blood stream while accommodating necessary clinical boundary conditions.

Chen, Haitao; Bockenfeld, Danny; Rempfer, Dietmar; Kaminski, Michael D.; Rosengart, Axel J.

2007-09-01

199

Rapid and selective separation for mixed proteins with thiol functionalized magnetic nanoparticles  

NASA Astrophysics Data System (ADS)

Thiol group functionalized silica-coated magnetic nanoparticles (Si-MNPs@SH) were synthesized for rapid and selective magnetic field-based separation of mixed proteins. The highest adsorption efficiencies of binary proteins, bovine serum albumin (BSA; 66 kDa; p I = 4.65) and lysozyme (LYZ; 14.3 kDa; p I = 11) were shown at the pH values corresponding to their own p I in the single-component protein. In the mixed protein, however, the adsorption performance of BSA and LYZ by Si-MNPs@SH was governed not only by pH but also by the molecular weight of each protein in the mixed protein.

Lee, Soo Youn; Ahn, Chi Young; Lee, Jiho; Lee, Jin Hyung; Chang, Jeong Ho

2012-05-01

200

Preparation of quantum dot-coated magnetic polystyrene nanospheres for cancer cell labelling and separation  

NASA Astrophysics Data System (ADS)

CdTe-coated magnetic polystyrene nanospheres (MPN) were prepared via a stepwise electrostatic self-assembly approach, and the conjugation of epidermal growth factor (EGF) to the MPN/CdTe core-shell nanocomposites was prepared by using 1-ethyl-3(3-dimethylamino propyl)-carbodiimide (EDC) as a cross-linking reagent. The MPN/CdTe and their bioconjugates yielded not only emitted bright fluorescence, but also exhibited superparamagnetism. The human breast cancer MDA-MB-435S cells could be labelled and rapidly separated by the MPN/CdTe-EGF bioconjugates. These magnetofluorescent nanospheres, consisting of magnetic spheres and quantum dots (QDs), may be of special interest for many biomedical applications.

Chu, Maoquan; Song, Xin; Cheng, Duo; Liu, Shupeng; Zhu, Jian

2006-07-01

201

Synthesis of new type of Au-magnetic nanocomposite and application for protein separation thereof  

NASA Astrophysics Data System (ADS)

We present a different strategy for synthesizing the Au-?-Fe2O3 bifunctional nanoparticle by using a larger (50 nm) Au nanoparticle as the core surrounded by smaller (10 nm) ?-Fe2O3 nanoparticles. The synthesis of the composite nanoparticles is quite facile based on a simple redox process whereby Fe2+ is used to reduce Au3+. The morphology and composition of the product is measured by transmission electron microscopy, X-ray powder diffraction and UV-vis spectroscopy. We demonstrate the utility of these as-prepared Au-?-Fe2O3 nanoparticles by showing they can be used to separate proteins in solution. For example, bovine serum is efficiently removed from an aqueous solution with the simple addition of the NPs and application of a small magnet. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis is performed to evaluate the fidelity and efficiency of the protein separation procedure.

Song, Yu; Tao, Ling; Shen, Xiangchun

2012-07-01

202

Formation and properties of magnetic chains for 100 nm nanoparticles used in separations of molecules and cells  

PubMed Central

Optical observations of 100 nm metallic magnetic nanoparticles are used to study their magnetic field induced self assembly. Chains with lengths of tens of microns are observed to form within minutes at nanoparticle concentrations of 1010 per mL. Chain rotation and magnetophoresis are readily observed, and SEM reveals that long chains are not simple single particle filaments. Similar chains are detected for several 100 nm commercial bio-separation nanoparticles. We demonstrate the staged magnetic condensation of different types of nanoparticles into composite structures and show that magnetic chains bind to immunomagnetically labeled cells, serving as temporary handles which allow novel magnetic cell manipulations.

Wilson, Robert J.; Hu, Wei; Fu, Cheryl Wong Po; Koh, Ai Leen; Gaster, Richard S.; Earhart, Christopher M.; Fu, Aihua; Heilshorn, Sarah C.; Sinclair, Robert; Wang, Shan X.

2009-01-01

203

Imaging of magnetic colloids under the influence of magnetic field by cryogenic transmission electron microscopy  

NASA Astrophysics Data System (ADS)

The application of superparamagnetic nanoparticles for in vivo magnetic resonance imaging (MRI) under external ac magnetic field has attracted considerable research efforts in recent years. However, it is unclear how superparamagnetic nanostructures arrange themselves in fluidic environment under external magnetic field. Here, we report direct visualization of the effect of applied magnetic field to the ferrofluids (about 6 nm superparamagnetic magnetite (Fe3O4) nanoparticle ``colloidal'' suspension) using the cryogenic transmission electron microscopy (cryo-TEM). While long dipole chains (up to millimeter range) of the magnetite along the magnetic lines are found in samples dried inside the magnetic field, only short dipole chains (within tens of nanometer scale) with random orientations are observed in the wet sample observed by cryo-TEM. In the wet sample, aggregations of medium-length dipole chains (up to hundreds of nanometer) can be observed at the areas where the nanoparticles are ``solidified'' when phase separation occurs. In situ formation of flux-closure rings is observed at the edge where vitreous ice sublimes due to high-energy electron radiation that leaves magnetite nanoparticles isolated in the vacuum. Such observations may help elucidate the nature of magnetic field-induced assembly in fluidic environment as in the physiological aqueous conditions in MRI and related applications.

Wu, Jinsong; Aslam, M.; Dravid, Vinayak P.

2008-08-01

204

Method and apparatus for separating gases based on electrically and magnetically enhanced monolithic carbon fiber composite sorbents  

DOEpatents

A method for separating gases or other fluids involves placing a magnetic field on a monolithic carbon fiber composite sorption material to more preferentially attract certain gases or other fluids to the sorption material to which a magnetic field is applied. This technique may be combined with the known pressure swing adsorption'' technique utilizing the same sorption material. 1 fig.

Judkins, R.R.; Burchell, T.D.

1999-07-20

205

Method and apparatus for separating gases based on electrically and magnetically enhanced monolithic carbon fiber composite sorbents  

DOEpatents

A method for separating gases or other fluids involves placing a magnetic field on a monolithic carbon fiber composite sorption material to more preferentially attract certain gases or other fluids to the sorption material to which a magnetic field is applied. This technique may be combined with the known "pressure swing adsorption" technique utilizing the same sorption material.

Judkins, Roddie R. (9917 Rainbow Dr., Knoxville, TN 37922); Burchell, Timothy D. (109 Greywood Pl., Oak Ridge, TN 37830)

1999-01-01

206

Cryo-electron tomography of cells: connecting structure and function  

Microsoft Academic Search

Cryo-electron tomography (cryo-ET) allows the visualization of cellular structures under close-to-life conditions and at molecular\\u000a resolution. While it is inherently a static approach, yielding structural information about supramolecular organization at\\u000a a certain time point, it can nevertheless provide insights into function of the structures imaged, in particular, when supplemented\\u000a by other approaches. Here, we review the use of experimental methods

Vladan Lu?i?; Andrew Leis; Wolfgang Baumeister

2008-01-01

207

Magnetic network model including loss separation and Preisach principles for the evaluation of core losses in devices  

NASA Astrophysics Data System (ADS)

In this paper, a method is developed to calculate the core loss in a switched reluctance machine. The magnetic circuit of the motor is described as a magnetic network. The electromagnetic behavior of each magnetic network element takes into account the iron loss using the Preisach model and the principle of loss separation. Using the numerical routines, the local core loss in the different motor sections is calculated. The global core loss is compared with the experimentally determined core loss.

Dupré, Luc; Sergeant, Peter; Vandenbossche, Lode

2005-05-01

208

Synthesis of teicoplanin-modified hybrid magnetic mesoporous silica nanoparticles and their application in chiral separation of racemic compounds.  

PubMed

Teicoplanin-conjugated mesoporous silica magnetic nanoparticles (TE-MSMNPs) were fabricated as novel chiral magnetic nano-selectors. Successful preparation of the functional magnetic mesoporous materials was achieved by grafting teicoplanin on N-(2-aminoethyl)-3-aminopropyltrimethoxysilane-modified mesoporous silica Fe3O4 magnetic nanoparticles (AEAPTMS-MSMNPs), and this was confirmed by various characterization techniques. The synthesized magnetic nanoparticles were regularly spherical and uniformly mesoporous with an average diameter of around 600 nm and a mean pore size of about 3.9 nm, respectively. These versatile magnetic nanoparticles were effective in a direct chiral separation of five racemic compounds in phosphate buffer. Much stronger interactions were observed with the (+)-enantiomers than with the (-)-enantiomers. After washing with water and ethanol by sonication, TE-MSMNPs could be reused at least three times with little efficiency loss. The functional magnetic mesoporous nanoparticles were easily separated from the racemic solutions using an external magnetic field. These magnetic nano-materials are suitable for enantiomer separations. PMID:23541694

Wu, Jingwei; Su, Ping; Huang, Jun; Wang, Siming; Yang, Yi

2013-03-13

209

Removal and recovery of phosphorus in wastewater by superconducting high gradient magnetic separation with ferromagnetic adsorbent  

NASA Astrophysics Data System (ADS)

Prevention of eutrophication for semi-enclosed bays and ponds is serious and important challenge. In spite of the advanced wastewater treatment, typically 1 mg/L phosphorus is discharged into public water bodies from wastewater treatment plants. The total amount of the discharged water is so large that the further improvement of the removal efficiency of phosphorus in the discharged water is demanded. On the other hand, recently phosphorus has become increasingly recognized as the important strategic material due to the global food problem. Therefore, the recovery and recycling of phosphorus is also important issue.In this work, removal and recovery of phosphorus from treated wastewater by High Gradient Magnetic Separation (HGMS) with ferromagnetic zirconium ferrite adsorbent were studied. Phosphorus in the treated wastewater could be removed from 1.12 mg/L to 0.03 mg/L by the HGMS system with 500 mg/L zirconium ferrite adsorbent for 5 min in adsorption time. The magnetic separation speed achieved 1 m/s at 1 T which was necessary for practical use. We also confirmed that phosphorus could be desorbed from zirconium ferrite adsorbent by alkali treatment in a short time.

Ishiwata, T.; Miura, O.; Hosomi, K.; Shimizu, K.; Ito, D.; Yoda, Y.

2010-11-01

210

Isolation/separation of plasmid DNA using hemoglobin modified magnetic nanocomposites as solid-phase adsorbent.  

PubMed

Hemoglobin (Hb) modified magnetic nanocomposites are prepared by immobilization of Hb onto the surface of amino-functionalized Fe(3)O(4)@SiO(2) magnetic nanoparticles via covalent bonding with glutaraldehyde as cross-linker. The obtained nanocomposites are characterized with FT-IR, SEM, XRD and surface charge analysis. A direct solid-phase extraction procedure for the isolation/separation of plasmid DNA using this nanocomposite as a novel adsorbent is thus developed. Some important experimental parameters governing the sorption efficiency, i.e., the pH of sample solution and the ionic strength, are investigated. The Hb modified magnetic nanocomposites provide a sorption capacity of 27.86 mg g(-1) for DNA. By using 2.0mg of the nanocomposites as sorption medium and a suitable acidity of pH 6.1, a sorption efficiency of 93% is achieved for 25 ?g mL(-1) of DNA in 1.0 mL of sample solution. Afterwards, the absorbed DNA could be readily recovered by using 1.0 mL of Tris-HCl buffer (pH 8.9, 0.01 mol L(-1)), giving rise to a recovery of ca. 68.3%. The present solid-phased extraction protocol is applied for the isolation of plasmid DNA from Escherichia coli culture, resulting in comparable yield and purity of plasmid DNA with respect to those obtained by using commercial kits. PMID:23141317

Chen, Xu-Wei; Mao, Quan-Xing; Liu, Jia-Wei; Wang, Jian-Hua

2012-08-07

211

Development of high gradient magnetic separation system for removing the metallic wear debris to be present in highly viscous fluid  

NASA Astrophysics Data System (ADS)

In the industrial plants processing highly viscous fluid such as foods or industrial materials, there is an issue of contamination by metallic wear debris originating from pipe of manufacturing line. It is necessary to remove the metallic wear debris in highly viscous fluid, since these debris causes quality loss. In this study, we developed a high gradient magnetic separation system by using superconducting magnet to remove the metallic wear debris. The particle trajectory simulation and the magnetic separation experiment were conducted with polyvinyl alcohol as a model material. As a result, ca. 100% and 92.2% of the separation efficiency was achieved respectively for the highly viscous fluid of 1 Pa s and 6 Pa s in viscosity, with 14 and 30 mesh magnetic filters.

Hayashi, S.; Mishima, F.; Akiyama, Y.; Nishijima, S.

2010-11-01

212

Magnetic properties of macroscopic colloid crystals of silica-coated FePt nanoparticles with controllable interstices for molecular separation  

NASA Astrophysics Data System (ADS)

This paper reports on the magnetic properties of macroscopic colloidal crystals comprising silica-encapsulated FePt nanoparticles which assembled into three dimensional regular arrays by magnetic crystallization. The crystals have potential for magnetic separation of paramagnetic chemical or biochemical entities (e.g., proteins) by providing local magnetic fields at the interstitial sites to promote magnetic retention of the entities of interest. Structural characterizations by transmission electron microscopy and small angle x-ray scattering using a synchrotron source indicate a hcp arrangement of the nanoparticles in the colloidal crystals. The crystals have a large surface area (110.6 m2 g-1) and a sharp pore size of 15 nm which is adjustable by controlling the silica shell thickness. Under applied fields, the colloidal crystals display substantially stronger magnetic responses than the unaligned particle assembly, thus favoring removal of the colloidal crystals from the mixture by magnetic means after magnetic separation. The potential of the colloidal crystals for separating paramagnetic biological or chemical species is demonstrated in absorption experiments using two proteins with and without a paramagnetic center.

Lo, Chester C. H.; Tsang, Shik Chi; Yu, Chih H.; Tam, Kin

2009-04-01

213

Separation of Plasmodium falciparum late stage-infected erythrocytes by magnetic means.  

PubMed

Unlike other Plasmodium species, P. falciparum can be cultured in the lab, which facilitates its study (1). While the parasitemia achieved can reach the ?40% limit, the investigator usually keeps the percentage at around 10%. In many cases it is necessary to isolate the parasite-containing red blood cells (RBCs) from the uninfected ones, to enrich the culture and proceed with a given experiment. When P. falciparum infects the erythrocyte, the parasite degrades and feeds from haemoglobin (2, 3). However, the parasite must deal with a very toxic iron-containing haem moiety (4, 5). The parasite eludes its toxicity by transforming the haem into an inert crystal polymer called haemozoin (6, 7). This iron-containing molecule is stored in its food vacuole and the metal in it has an oxidative state which differs from the one in haem (8). The ferric state of iron in the haemozoin confers on it a paramagnetic property absent in uninfected erythrocytes. As the invading parasite reaches maturity, the content of haemozoin also increases (9), which bestows even more paramagnetism on the latest stages of P. falciparum inside the erythrocyte. Based on this paramagnetic property, the latest stages of P. falciparum infected-red blood cells can be separated by passing the culture through a column containing magnetic beads. These beads become magnetic when the columns containing them are placed on a magnet holder. Infected RBCs, due to their paramagnetism, will then be trapped inside the column, while the flow-through will contain, for the most part, uninfected erythrocytes and those containing early stages of the parasite. Here, we describe the methodology to enrich the population of late stage parasites with magnetic columns, which maintains good parasite viability (10). After performing this procedure, the unattached culture can be returned to an incubator to allow the remaining parasites to continue growing. PMID:23486405

Coronado, Lorena Michelle; Tayler, Nicole Michelle; Correa, Ricardo; Giovani, Rita Marissa; Spadafora, Carmenza

2013-03-02

214

Investigation of the process of diamagnetic particle separation in a high-gradient ordered-structure magnetic field  

NASA Astrophysics Data System (ADS)

On the basis of the model of a flow-type magnetic filter with a transversely magnetized ordered system of long ferromagnetic rods of rectangular cross section, the process of high-gradient magnetic separation of microscopic diamagnetic particles (potato starch granules of sizes 8-30 ?m) from a liquid suspension has been investigated. The registered laws of change in the concentration and size distribution of particles at the suspension outlet from the filter agree with the theoretical conclusions obtained from the analysis of the magnetic field structure and thecharacter of the particle motion in the filter volume.

Kashevskii, B. É.; Kashevskii, S. É.; Prokhorov, I. V.; Zholud', A. M.

2011-05-01

215

Cryo-Tracker mass gauging system testing in a large-scale expendable launch vehicle LOX tank simulator  

NASA Astrophysics Data System (ADS)

Sierra Lobo tested its patented Cryo-Tracker(R) probe and Mass Gauging System in a large scale Expendable Launch Vehicle (ELV) liquid oxygen tank simulation for NASA. Typical Liquid Oxygen (LOX) tank operations were simulated at Lockheed Martin's Engineering Propulsion Laboratory in Denver, Colorado. The Cryo-Tracker(R) probe is 33 feet long, the longest built to date. It was mounted in the tank at only two locations, separated by 26 feet. Each test simulated typical Lockheed Martin booster pre-launch tanking operations, including filling the tank with LOX at fill rates typically used at the launch pad, and maintaining the fill level for a period representative of a typical pad hold. The Cryo-Tracker(R) Mass Gauging System was the primary instrument used for monitoring the fill and controlling the topping operations. Each test also simulated a typical flight profile, expelling the LOX at representative pressures and expulsion flow rates. During expulsion, the Cryo-Tracker(R) System served to generate an Engine Cut-Off (ECO) signal. Test objectives were as follows: Cryo-Tracker(R) data will be validated by flight-like propellant instruments currently used in launch vehicles; the probe will survive the harsh environment (which will be documented by a digital video camera) with no loss of signal or structural integrity; the system will successfully measure liquid levels and temperatures under all conditions and calculate propellant mass in real-time; the system will successfully demonstrate its feasibility as a control sensor for LOX filling and topping operations, as well as for engine cut-off. All objectives were met and the test results are presented.

Schieb, Daniel J.; Haberbusch, Mark S.; Yeckley, Alexander J.

2006-06-01

216

Research on high gradient magnetic separation of pneumatic conveyed powder products: Investigation from the viewpoint of interparticle interactions  

NASA Astrophysics Data System (ADS)

The separation and removal of the metallic debris originating from pipe of manufacturing line are required in the manufacturing process of the fine particle products. In this study, we develop a high gradient magnetic separation system (HGMS) under a dry process by using a superconducting magnet to remove ferromagnetic particles such as the material stainless steel (SUS). To avoid the obstruction of the separation part by aggregation of the processed material, we develop a magnetic separation system using a pneumatic conveying as a new transportation method of the particles.The magnetic separations were experimented under the same conditions on different days, but the results were different. The reason is considered to be the difference in adhesion force between the particles due to a change of humidity, we have measured the adhesion forces between the ferromagnetic particles and the paramagnetic medium particles using AFM (Atomic Force Microscope) while changing the humidity. As a result, the adhesion force between the particles increased with the increasing of humidity. Furthermore, we saw that the effect of relative humidity was larger in the adhesion force of alumina with larger cohesive property. Based on these results, an appropriate condition of the separation experiment was clarified. And a dehumidification mechanism was introduced.

Senkawa, Kohei; Nakai, Yuki; Mishima, Fumihito; Akiyama, Yoko; Nishijima, Shigehiro

2013-01-01

217

Separation of semiconducting and ferromagnetic FeSi2-nanoparticles by magnetic filtering  

NASA Astrophysics Data System (ADS)

We have investigated the potential of solution-processed ?-phase iron disilicide (FeSi2) nanoparticles as a novel semiconducting material for photovoltaic applications. Combined ultraviolet-visible absorption and photothermal deflection spectroscopy measurements have revealed a direct band gap of 0.85 eV and, therefore, a particularly high absorption in the near infrared. With the help of Fourier-transform infrared and X-ray photoelectron spectroscopy, we have observed that exposure to air primarily leads to the formation of a silicon oxide rather than iron oxide. Mössbauer measurements have confirmed that the nanoparticles possess a phase purity of more than 99%. To diminish the small fraction of metallic iron impurities, which were detected by superconducting quantum interference device magnetometry and which would act as unwanted Auger recombination centers, we present a novel concept to magnetically separate the FeSi2 nanoparticles (NPs). This process leads to a reduction of more than 95% of the iron impurities.

Aigner, Willi; Niesar, Sabrina; Mehmedovic, Ervin; Opel, Matthias; Wagner, Friedrich E.; Wiggers, Hartmut; Stutzmann, Martin

2013-10-01

218

Separation of the Magnetic Field into Parts Produced by Internal and External Sources  

NASA Astrophysics Data System (ADS)

Given the total magnetic field on a toroidal plasma surface, a method for decomposing the field into a part due to internal currents (often the plasma) and a part due to external currents is presented. The decomposition exploits Laplace theory which is valid in the vacuum region between the plasma surface and the chamber walls. The method does not assume toroidal symmetry, and it is partly based on Merkel's 1986 work on vacuum field computations. A change in the plasma shape is produced by the total normal field perturbation on the plasma surface. This method allows a separation of the total normal field perturbation into a part produced by external currents and a part produced by the plasma response.

Lazanja, David

2005-10-01

219

Experimental Signatures of Intrinsic Phase Separation in Magnetically Doped Two-Dimensional Electron Gas  

NASA Astrophysics Data System (ADS)

We theoretically study the properties of a recently observed inhomogeneous phase [1] preceding the metal-insulator transition in Mn-doped two-dimensional electron gas (2DEG). We show that the competition between the carrier-induced (ferromagnetic) double-exchange interaction, and the anti-ferromagnetic ``super-exchange'' interaction of local Mn moments leads to an intrinsic phase separation (PS) at sufficiently low carrier density. Our results establish a dramatic effect of such a PS on the transport properties of the system, resulting in very strong (activated) temperature and magnetic field dependence, but anomalously weak density dependence of the resistivity under the PS dome-in striking agreement with experiments [1]. Based on our results, we argue that such exotic transport behavior should be considered as a signature of intrinsic PS, in dramatic contrast to what is found in situations where PS is driven by disorder.

Terletska, Hanna; Dobrosavljevic, Vladimir

2010-11-01

220

Imaging biological structures with the cryo atomic force microscope.  

PubMed Central

It has long been recognized that one of the major limitations in biological atomic force microscopy (AFM) is the softness of most biological samples, which are easily deformed or damaged by the AFM tip, because of the high pressure in the contact area, especially from the very sharp tips required for high resolution. Another is the molecular motion present at room temperature due to thermal fluctuation. Using an AFM operated in liquid nitrogen vapor (cryo-AFM), we demonstrate that cryo-AFM can be applied to a large variety of biological samples, from immunoglobulins to DNA to cell surfaces. The resolution achieved with cryo-AFM is much improved when compared with AFM at room temperature with similar specimens, and is comparable to that of cryo-electron microscopy on randomly oriented macromolecules. We will also discuss the technical problems that remain to be solved for achieving even higher resolution with cryo-AFM and other possible applications of this novel technique. Images FIGURE 1 FIGURE 2 FIGURE 3 FIGURE 4 FIGURE 5 FIGURE 6 FIGURE 7

Zhang, Y; Sheng, S; Shao, Z

1996-01-01

221

Optimized high gradient magnetic separation for isolation of Plasmodium-infected red blood cells  

PubMed Central

Background Highly purified infected red blood cells (irbc), or highly synchronized parasite cultures, are regularly required in malaria research. Conventional isolation and synchronization rely on density and osmotic fragility of irbc, respectively. High gradient magnetic separation (HGMS) offers an alternative based on intrinsic magnetic properties of irbc, avoiding exposure to chemicals and osmotic stress. Successful HGMS concentration in malaria research was previously reported using polymer coated columns, while HGMS depletion has not been described yet. This study presents a new approach to both HGMS concentration and depletion in malaria research, rendering polymer coating unnecessary. Methods A dipole magnet generating a strong homogenous field was custom assembled. Polypropylene syringes were fitted with one-way stopcocks and filled with stainless steel wool. Rbc from Plasmodium falciparum cultures were resuspended in density and viscosity optimized HGMS buffers and HGMS processed. Purification and depletion results were analysed by flow cytometer and light microscopy. Viability was evaluated by calculating the infection rate after re-culturing of isolates. Results In HGMS concentration, purity of irbc isolates from asynchronous cultures consistently ranged from 94.8% to 98.4% (mean 95.7%). With further optimization, over 90% of isolated irbc contained segmented schizonts. Processing time was less than 45 min. Reinfection rates ranged from 21.0% to 56.4%. In HGMS depletion, results were comparable to treatment with sorbitol, as demonstrated by essentially identical development of cultures. Conclusion The novel HGMS concentration procedure achieves high purities of segmented stage irbc from standard asynchronous cultures, and is the first HGMS depletion alternative to sorbitol lysis. It represents a simple and highly efficient alternative to conventional irbc concentration and synchronization methods.

2010-01-01

222

Templated synthesis of monodisperse mesoporous maghemite/silica microspheres for magnetic separation of genomic DNA  

NASA Astrophysics Data System (ADS)

A novel method is described for the preparation of superparamagnetic mesoporous maghemite (?-Fe2O3)/silica (SiO2) composite microspheres to allow rapid magnetic separation of DNA from biological samples. With magnetite (Fe3O4) and silica nanoparticles as starting materials, such microspheres were synthesized by the following two consecutive steps: (1) formation of monodispersed organic/inorganic hybrid microspheres through urea-formaldedyde (UF) polymerization and (2) removal of the organic template and phase transformation of Fe3O4 to ?-Fe2O3 by calcination at elevated temperatures. The as-synthesized particles obtained by heating at temperature 300 °C feature spherical shape and uniform particle size (dparticle=1.72 ?m), high saturation magnetization (Ms=17.22 emu/g), superparamagnetism (Mr/Ms=0.023), high surface area (SBET=240 m2/g), and mesoporosity (dpore=6.62 nm). The composite microsphere consists of interlocked amorphous SiO2 nanoparticles, in which cubic ?-Fe2O3 nanocrystals are homogeneously dispersed and thermally stable against ?- to ?-phase transformation at temperatures up to 600 °C. With the exposed iron oxide nanoparticles coated with a thin layer of silica shell, the magnetic microspheres were used as a solid-phase adsorbent for rapid extraction of genomic DNA from plant samples. The results show that the DNA templates isolated from pea and green pepper displayed single bands with molecular weights greater than 8 kb and A260/A280 values of 1.60-1.72. The PCR amplification of a fragment encoding the endogenous chloroplast ndhB gene confirmed that the DNA templates obtained were inhibitor-free and amenable to sensitive amplification-based DNA technologies.

Chen, Feng; Shi, Ruobing; Xue, Yun; Chen, Lei; Wan, Qian-Hong

2010-08-01

223

Control of separated flow in a reflected shock interaction using a magnetically-accelerated surface discharge  

NASA Astrophysics Data System (ADS)

A numerical investigation was carried out to explore the effects of a magnetically-accelerated surface discharge on a separated, turbulent boundary layer in supersonic flow. The geometry and test conditions were chosen for comparison to experiments carried out at Princeton University. For those studies, a reflected shock interaction was created using a 14° shock generator acting on an incoming turbulent boundary layer with a Reynolds number based on momentum thickness of 1 × 104 and a freestream Mach number of 2.6. Three-dimensional, Reynolds-averaged, Navier-Stokes (RANS) calculations were carried out to simulate the experiments, using the US3D code developed at the University of Minnesota. The baseline code was modified to include a semi-empirical model of the surface discharge actuator, implemented through source terms in the momentum equation, vibrational energy equation, and total energy equation. The computational results for the baseline flow and several control cases were compared to experimental measurements of mean surface pressure. The level of discrepancy was typical of well-resolved RANS computations of three-dimensional, separated flows: qualitative agreement was obtained, and the general experimental trends were captured by the numerical model. Substantial three-dimensionality was observed even in the baseline flow, and significant changes in the flow topology were observed with the application of the actuator. Because of the highly three-dimensional nature of this shock interaction, the initial interpretation of the experiments may need to be revisited.

Atkinson, Michael D.; Poggie, Jonathan; Camberos, José A.

2012-12-01

224

Synthesis and performance of novel magnetically separable nanospheres of titanium dioxide photocatalyst with egg-like structure  

Microsoft Academic Search

A magnetically separable photocatalyst TiO2\\/SiO2\\/NiFe2O4 (TSN) nanosphere with egg-like structure was prepared by a unique process that combined a liquid catalytic phase transformation method, reverse micelle technique and chemical precipitation means. The prepared photocatalyst shows high photocatalytic activity for the degradation of methyl orange in water. The magnetic property measurements indicate that the photocatalyst possesses a superparamagnetic nature. It can

Shihong Xu; Wenfeng Shangguan; Jian Yuan; Mingxia Chen; Jianwei Shi; Zhi Jiang

2008-01-01

225

76 FR 4338 - Research and Development Strategies for Compressed & Cryo-Compressed Hydrogen Storage Workshops  

Federal Register 2010, 2011, 2012, 2013

...Compressed & Cryo- Compressed Hydrogen Storage Workshops AGENCY: Fuel Cell Technologies...Laboratory, in conjunction with the Hydrogen Storage team of the EERE Fuel Cell Technologies...compressed and cryo-compressed hydrogen storage in the Washington, DC metro area....

2011-01-25

226

An experimental VLT cryo-cooler instrumentation vibration analysis  

NASA Astrophysics Data System (ADS)

Cryo-coolers are widely used to provide the required temperature levels of ESO's VLT instrumentation suite, mainly for infrared instruments and their detectors. Nevertheless, mechanical vibrations induced by these refrigerator systems became a serious issue over the last years. Especially for the extremely sensitive VLT-Interferometer even micro vibration levels can be critical. As a consequence ESO started some time ago a comprehensive vibration reduction program. Major tasks involved are the quantification of typical cryo-cooler instrument vibration levels and their impact on the VLT / VLT-I optical stability. This paper describes the design, construction and calibration of a dedicated VLT dummy instrument comprising six powerful state-of-the-art 2-stage cold heads and the subsequent comprehensive vibration measurement test campaign. As a result trendsetting cryo-cooler instrument design and operation recommendations are presented.

Jakob, Gerd; Lizon, Jean-Louis

2012-09-01

227

Analyses of Subnanometer Resolution Cryo-EM Density Maps  

PubMed Central

Today, electron cryomicroscopy (cryo-EM) can routinely achieve subnanometer resolutions of complex macromolecular assemblies. From a density map, one can extract key structural and functional information using a variety of computational analysis tools. At subnanometer resolution, these tools make it possible to isolate individual subunits, identify secondary structures, and accurately fit atomic models. With several cryo-EM studies achieving resolutions beyond 5 Å, computational modeling and feature recognition tools have been employed to construct backbone and atomic models of the protein components directly from a density map. In this chapter, we describe several common classes of computational tools that can be used to analyze and model subnanometer resolution reconstructions from cryo-EM. A general protocol for analyzing subnanometer resolution density maps is presented along with a full description of steps used in analyzing the 4.3 Å resolution structure of Mm-cpn.

Baker, Matthew L.; Baker, Mariah R.; Hryc, Corey F.; DiMaio, Frank

2011-01-01

228

CRUCIAL: CryoSat+ Land and Inland Water  

NASA Astrophysics Data System (ADS)

The CryoSat-2 SIRAL altimeter presents a unique opportunity for inland water height retrieval. In order to maximise the potential of this new dataset the ESA CRUCIAL (CryoSat+ Land and Inland Water) contract has been set up to investigate the application of CryoSat-2 data over land and inland water. When operating in SAR mode CryoSat-2 obtains waveforms at an unprecedented resolution alongtrack, allowing far smaller inland water targets then previously possible to be acquired. Prior work performed with the Envisat Individual echoes has shown that a high Pulse Repetition Frequency (PRF) allows successful measurements to be obtained from river targets as small as 25m across. SAR Full Bit Rate (FBR) data are acquired over the Mekong River area, including the Mekong Delta itself. This region provides the ideal test-bed for obtaining small target inland water measurements and early results of FBR waveform reconstruction and analysis are presented within this paper. Whilst FBR data over land are available in a few test regions, over much of the Earth's land surface measurements are acquired in Low Resolution Mode. These data are comparable to those obtained by conventional altimeters, such as ERS-2 and EnviSat. The non-repeat orbit of CryoSat-2 presents a new challenge to inland water measurement by satellite radar altimetry, as repeat time-series are no longer possible. However, CryoSat-2 data produce stage measurements from along the course of rivers more regularly than the 35-days of previous ESA missions. New methodologies must be investigated to allow hydrologists to harness the full benefit of these new data. This paper presents initial findings of investigations over major river systems captured in LRM mode and a first look at results over the Mekong area from SAR FBR. This additional data will also be used to enhance and improve the Altimetry Corrected Elevations (ACE2) Global Digital Elevation Models.

Berry, Philippa; Smith, Richard; Salloway, Mark; Lucas, Bruno Manuel; Dinardo, Salvatore; Benveniste, Jérôme

2013-04-01

229

Kodak AMSD mirror program: overview and cryo test results  

NASA Astrophysics Data System (ADS)

Kodak AMSD mirror processing was successfully completed, and the mirror was cryo tested at NASA. This paper reviews the entire AMSD program at Eastman Kodak Company from mirror blank production to mirror processing and metrology. To achieve the most information possible with respect to the flight configuration planned for JWST, the original Kodak AMSD test plan was modified. This change in plan is discussed and how it impacts the future path for AMSD. The AMSD Phase III program is also discussed and the status of that program is provided. In addition, this paper discusses performance of the mirror at cryo temperatures.

Matthews, Gary; Barrett, David; Bolton, James; Dahl, Roger; Michaels, Elise; Mallette, Mark; Johnson, Josh

2004-01-01

230

Separation of charge-order and magnetic QCPs in heavy fermions and high Tc cuprates  

NASA Astrophysics Data System (ADS)

The Fermi surface topology of high temperature superconductors inferred from magnetic quantum oscillation measurements provides clues for the origin of unconventional pairing thus previously not accessed by other spectroscopy techniques. While the overdoped regime of the high Tc phase diagram has a large Fermi surface consistent with bandstructure calculations, the underdoped regime of YBa2Cu2O6+x is found to be composed of small pockets. There is considerable debate as to whether the small observed ``pocket'' is hole-like or electron-like- whether the Fermi surface is best described by a t-J model or a conventional band folding picture- whether or not a Fermi liquid description applies- or- whether bilayer coupling splits the degeneracy of the observed pockets. We (myself and collaborators) have now collected an extensive body of experimental data that brings this debate to rest, but raises new questions about the nature of itinerant magnetism in underdoped high Tc cuprates. Quantum oscillation measurements are performed on multiple samples in magnetic fields extending to 85 T, temperatures between 30 mK (dilution fridge in dc fields to 45 T) and 18 K, over a range of hole dopings and with samples rotated in-situ about multiple axes with respect to the magnetic field. We perform a topographical map of the Fermi surface, enabling the in-plane shape of one of the pockets to be determined- imposing stringent constraints on the origin of the Fermi surface. While quantum oscillations measurements are consistent with a topological Fermi surface change associated with magnetism near optimal doping, they also point to a secondary instability deep within the underdoped regime beneath a high Tc superconducting sub-dome. An steep upturn in the quasiparticle effective mass is observed on underdoping, suggestive of a quantum critical point near x= 0.46 separating the metallic regime (composed of small pockets) from a more underdoped insulating charge-ordered regime (earlier reported in neutron scattering measurements). Our findings suggest the importance of two critical instabilities affecting the Fermi surface beneath the high Tc superconducting dome(s). While one of these has been proposed to provide the likely origin of unconventional pairing in the cuprates, the other can be an important factor in boosting transition temperatures. [4pt] This work is supported by the DoE BES grant ``Science in 100 T''. The author would like to thank collaborators S. E. Sebastian, C. H. Mielke, P. A. Goddard, M. M. Altarawneh, R. Liang, D. A. Bonn, W. N. Hardy and G. G. Lonzarich, and supporting staff at the National High Magnetic Field Laboratory (NHMFL). Quantum oscillation experiments are performed at the NHMFL, which is funded by the NSF with support from the DoE and State of Florida.

Harrison, Neil

2010-03-01

231

Fabrication of anisotropic porous silica monoliths by means of magnetically controlled phase separation in sol-gel processes.  

PubMed

Sol-gel accompanied by phase separation is an established method for the preparation of porous silica monoliths with well-defined macroporosity, which find numerous applications. In this work, we demonstrate how the addition of (superpara)magnetic nanocolloids as templates to a system undergoing a sol-gel transition with phase separation leads to the creation of monoliths with a strongly anisotropic structure. It is known that magnetic nanocolloids respond to the application of an external magnetic field by self-assembling into columnar structures. The application of a magnetic field during the chemically driven spinodal decomposition induced by the sol-gel transition allows one to break the symmetry of the system and promote the growth of elongated needle-like silica domains incorporating the magnetic nanocolloids, aligned in the direction of the field. It is found that this microstructure imparts a strong mechanical anisotropy to the materials, with a ratio between the Young's modulus values measured in a direction parallel and perpendicular to the one of the field as high as 150, and an overall smaller average macropores size as compared to isotropic monoliths. The microstructure and properties of the porous monoliths can be controlled by changing both the system composition and the strength of the applied magnetic field. Our monoliths represent the first example of materials prepared by magnetically controlling a phase transition occurring via spinodal decomposition. PMID:22849804

Furlan, Marco; Lattuada, Marco

2012-08-14

232

Spin-charge separation in the t-J model: Magnetic and transport anomalies  

NASA Astrophysics Data System (ADS)

A real spin-charge separation scheme is found based on a saddle-point state of the t-J model. In the one-dimensional (1D) case, such a saddle-point reproduces the correct asymptotic correlations at the strong-coupling fixed point of the model. In the two-dimensional (2D) case, the transverse gauge field confining spinon and holon is shown to be gapped at finite doping so that a spin-charge deconfinement is obtained for its first time in 2D. The gap in the gauge fluctuation disappears at half-filling limit, where a long-range antiferromagnetic order is recovered at zero temperature and spinons become confined. The most interesting features of spin dynamics and transport are exhibited at finite doping where exotic residual couplings between spin and charge degrees of freedom lead to systematic anomalies with regard to a Fermi-liquid system. In spin dynamics, a commensurate antiferromagnetic fluctuation with a small, doping-dependent energy scale is found, which is characterized in momentum space by a Gaussian peak at (?/a,?/a) with a doping-dependent width (~ ?? , ? is the doping concentration). This commensurate magnetic fluctuation contributes a non-Korringa behavior for the NMR spin-lattice relaxation rate. There also exists a characteristic temperature scale below thich a pseudogap behavior appears in the spin dynamics. Furthermore, an incommensurate magnetic fluctuation is also obtained at a finite energy regime. In the transport, a strong-range phase intereference leads to an effective holon Lagrangian which can give rise to a series of interesting phenomena including linear-T resistivity and a T2 Hall angle. We discuss the striking similarities of these theoretical features with those found in the high-Tc cuprates and give a consistent picture for the latter. Electronic properties like Fermi surface and superconducting pairing in this framework are also discussed.

Weng, Z. Y.; Sheng, D. N.; Ting, C. S.

1995-07-01

233

In situ magnetic separation of antibody fragments from Escherichia coli in complex media  

PubMed Central

Background In situ magnetic separation (ISMS) has emerged as a powerful tool to overcome process constraints such as product degradation or inhibition of target production. In the present work, an integrated ISMS process was established for the production of his-tagged single chain fragment variable (scFv) D1.3 antibodies (“D1.3”) produced by E. coli in complex media. This study investigates the impact of ISMS on the overall product yield as well as its biocompatibility with the bioprocess when metal-chelate and triazine-functionalized magnetic beads were used. Results Both particle systems are well suited for separation of D1.3 during cultivation. While the triazine beads did not negatively impact the bioprocess, the application of metal-chelate particles caused leakage of divalent copper ions in the medium. After the ISMS step, elevated copper concentrations above 120 mg/L in the medium negatively influenced D1.3 production. Due to the stable nature of the model protein scFv D1.3 in the biosuspension, the application of ISMS could not increase the overall D1.3 yield as was shown by simulation and experiments. Conclusions We could demonstrate that triazine-functionalized beads are a suitable low-cost alternative to selectively adsorb D1.3 fragments, and measured maximum loads of 0.08 g D1.3 per g of beads. Although copper-loaded metal-chelate beads did adsorb his-tagged D1.3 well during cultivation, this particle system must be optimized by minimizing metal leakage from the beads in order to avoid negative inhibitory effects on growth of the microorganisms and target production. Hereby, other types of metal chelate complexes should be tested to demonstrate biocompatibility. Such optimized particle systems can be regarded as ISMS platform technology, especially for the production of antibodies and their fragments with low stability in the medium. The proposed model can be applied to design future ISMS experiments in order to maximize the overall product yield while the amount of particles being used is minimized as well as the number of required ISMS steps.

2013-01-01

234

Magnetically separable nanocomposites with photocatalytic activity under visible light for the selective transformation of biomass-derived platform molecules  

EPA Science Inventory

Novel magnetically separable TiO2-guanidine-(Ni,Co)Fe2O4 nanomaterials were prepared and characterised by a series of techniques including XRD, SEM, TEM, N2 physisorption as well as XPS and subsequently tested for their photocatalytic activities in the selective transformation of...

235

Multifunctional Magnetic-Optical Nanoparticle Probes for Simultaneous Detection, Separation, and Thermal Ablation of Multiple Pathogens  

Microsoft Academic Search

Multifunctional nanoparticles possessing magnetization and near-infrared (NIR) absorption have warranted interest due to their significant applications in magnetic resonance imaging, diagnosis, bioseparation, target delivery, and NIR photothermal ablation. Herein, the site-selective assembly of magnetic nanoparticles onto the ends or ends and sides of gold nanorods with different aspect ratios (ARs) to create multifunctional nanorods decorated with varying numbers of magnetic

Chungang Wang; Joseph Irudayaraj

2010-01-01

236

A Phos-tag-based magnetic-bead method for rapid and selective separation of phosphorylated biomolecules.  

PubMed

A simple and efficient method based on magnetic-bead technology has been developed for the separation of phosphorylated and nonphosphorylated low-molecular-weight biomolecules, such as nucleotides, phosphorylated amino acids, or phosphopeptides. The phosphate-binding site on the bead is an alkoxide-bridged dinuclear zinc(II) complex with 1,3-bis(pyridin-2-ylmethylamino)propan-2-olate (Phos-tag), which is linked to a hydrophilic cross-linked agarose coating on a magnetic core particle. All steps for the phosphate-affinity separation are conducted in buffers of neutral pH with 50 ?L of the magnetic beads in a 1.5-mL microtube. The entire separation protocol for phosphomonoester-type compounds, from addition to elution, requires less than 12 min per sample if the buffers and the zinc(II)-bound Phos-tag magnetic beads have been prepared in advance. The phosphate-affinity magnetic beads are reusable at least 15 times without a decrease in their phosphate-binding ability and they are stable for three months in propan-2-ol. PMID:23523882

Tsunehiro, Masaya; Meki, Yuma; Matsuoka, Kanako; Kinoshita-Kikuta, Emiko; Kinoshita, Eiji; Koike, Tohru

2013-03-08

237

Separation of Sudan dyes from chilli powder by magnetic molecularly imprinted polymer.  

PubMed

A simple method based on magnetic molecularly imprinted polymers (MMIPs) for the separation of Sudan dyes from chilli powder samples has been developed. The MMIPs were synthesized as follows: the Fe(3)O(4) nanoparticles were encapsulated with a SiO(2) shell and functionalized with -CH=CH(2), then the polymers were further fabricated by surface-imprinted polymerization using Sudan IV as template molecule, methacrylic acid as functional monomer, and ethylene glycol dimethacrylate as cross-linking agent. The prepared MMIPs were characterized by scanning electron microscope, Fourier transform infrared spectrometry and physical property measurement system. The isothermal absorption experiment, kinetics absorption experiment and selectivity of MMIPs were tested. The analytes were determined by high performance liquid chromatography. Under the optimal conditions, the limits of detection of the four Sudan dyes are 6.2, 1.6, 4.3 and 4.5 ng g(-1), respectively. The precision expressed as relative standard deviation ranging from 4.8% to 9.1% was obtained. In all three fortified levels (25, 250 and 2500 ng g(-1)), recoveries of Sudan dyes were in the range of 79.9-87.8%. PMID:23141623

Piao, Chunying; Chen, Ligang

2012-10-26

238

Magnetic Structure and Phase Separation in Epitaxial SrCoOx Thin Films  

NASA Astrophysics Data System (ADS)

Bulk SrCoOx separates into three distinct ferromagnetic phases as the oxygen content is increased from x = 2.75 to 3.0, corresponding to TC = 165 K (SrCoO2.75), TC = 220 K (SrCoO2.88), and TC = 280 K (SrCoO3.0). Over this composition, the lattice evolves smoothly and remains a single crystallographic phase. Using pulsed laser deposition and electrochemical oxidation, we have prepared epitaxial films of SrCoOx of varying thickness and orientation on SiTiO3 substrates. While in polycrystalline samples intermediate oxygen concentrations show a two-phase magnetic behavior, 100nm thick (0 0 1) films remain single phase but still favor the same ferromagnetic transitions. Thicker, 150 nm (1 1 1) films also order at comparable TC's, but again show two-phase behavior during deoxidation. Resonant x-ray diffraction on these samples reveals both commensurate and incommensurate ordering dependent on the oxidation state. This implies a charge or orbital ordering which may be influenced by finite size effects.

Rueckert, F. J.; Abughayada, C.; Sabok, S. A.; He, F.; Mohottala, H.; Budnick, J. I.; Hines, W. A.; Dabrowski, B.; Wells, B. O.

2013-03-01

239

The magnetic field induced phase separation in a model of a superconductor with local electron pairing  

NASA Astrophysics Data System (ADS)

We have studied the extended Hubbard model with pair hopping in the atomic limit for arbitrary electron density and chemical potential and focus on paramagnetic effects of the external magnetic field. The Hamiltonian considered consists of (i) the effective on-site interaction U and (ii) the intersite charge exchange interactions I, determining the hopping of electron pairs between nearest-neighbour sites. The phase diagrams and thermodynamic properties of this model have been determined within the variational approach (VA), which treats the on-site interaction term exactly and the intersite interactions within the mean-field approximation. Our investigation of the general case shows that the system can exhibit not only the homogeneous phases—superconducting (SS) and non-ordered (NO)—but also the phase separated states (PS: SS-NO). Depending on the values of interaction parameters, the PS state can occur in higher fields than the SS phase (field induced PS). Some ground state results beyond the VA are also presented.

Kapcia, Konrad; Robaszkiewicz, Stanis?aw

2013-02-01

240

The magnetic field induced phase separation in a model of a superconductor with local electron pairing.  

PubMed

We have studied the extended Hubbard model with pair hopping in the atomic limit for arbitrary electron density and chemical potential and focus on paramagnetic effects of the external magnetic field. The Hamiltonian considered consists of (i) the effective on-site interaction U and (ii) the intersite charge exchange interactions I, determining the hopping of electron pairs between nearest-neighbour sites. The phase diagrams and thermodynamic properties of this model have been determined within the variational approach (VA), which treats the on-site interaction term exactly and the intersite interactions within the mean-field approximation. Our investigation of the general case shows that the system can exhibit not only the homogeneous phases-superconducting (SS) and non-ordered (NO)-but also the phase separated states (PS: SS-NO). Depending on the values of interaction parameters, the PS state can occur in higher fields than the SS phase (field induced PS). Some ground state results beyond the VA are also presented. PMID:23334285

Kapcia, Konrad; Robaszkiewicz, Stanis?aw

2013-02-13

241

Cryomesh: a new substrate for cryo-electron microscopy.  

PubMed

Here we evaluate a new grid substrate developed by ProtoChips Inc. (Raleigh, NC) for cryo-transmission electron microscopy. The new grids are fabricated from doped silicon carbide using processes adapted from the semiconductor industry. A major motivating purpose in the development of these grids was to increase the low-temperature conductivity of the substrate, a characteristic that is thought to affect the appearance of beam-induced movement (BIM) in transmission electron microscope (TEM) images of biological specimens. BIM degrades the quality of data and is especially severe when frozen biological specimens are tilted in the microscope. Our results show that this new substrate does indeed have a significant impact on reducing the appearance and severity of beam-induced movement in TEM images of tilted cryo-preserved samples. Furthermore, while we have not been able to ascertain the exact causes underlying the BIM phenomenon, we have evidence that the rigidity and flatness of these grids may play a major role in its reduction. This improvement in the reliability of imaging at tilt has a significant impact on using data collection methods such as random conical tilt or orthogonal tilt reconstruction with cryo-preserved samples. Reduction in BIM also has the potential for improving the resolution of three-dimensional cryo-reconstructions in general. PMID:20082728

Yoshioka, Craig; Carragher, Bridget; Potter, Clinton S

2010-02-01

242

Preparation of macromolecular complexes for cryo-electron microscopy  

PubMed Central

This protocol describes the preparation of frozen-hydrated single-particle specimens of macromolecular complexes. First, it describes how to create a grid surface coated with holey carbon by first inducing holes in a Formvar film to act as a template for the holey carbon that is stable under cryo-electron microscopy (cryo-EM) conditions and is sample-friendly. The protocol then describes the steps required to deposit the homogeneous sample on the grid and to plunge-freeze the grid into liquid ethane at the temperature of liquid nitrogen, so that it is suitable for cryo-EM visualization. It takes 4–5 h to make several hundred holey carbon grids and about 1 h to make the frozen-hydrated grids. The time required for sample purification varies from hours to days, depending on the sample and the specific procedure required. A companion protocol details how to collect cryo-EM data using an FEI Tecnai transmission electron microscope that can subsequently be processed to obtain a three-dimensional reconstruction of the macromolecular complex.

Grassucci, Robert A; Taylor, Derek J; Frank, Joachim

2009-01-01

243

Correlative cryo-electron tomography and optical microscopy of cells.  

PubMed

The biological processes occurring in a cell are complex and dynamic, and to achieve a comprehensive understanding of the molecular mechanisms underlying these processes, both temporal and spatial information is required. While cryo-electron tomography (cryoET) provides three-dimensional (3D) still pictures of near-native state cells and organelles at molecular resolution, fluorescence light microscopy (fLM) offers movies of dynamic cellular processes in living cells. Combining and integrating these two commonly used imaging modalities (termed correlative microscopy) provides a powerful means to not only expand the imaging scale and resolution but also to complement the dynamic information available from optical microscopy with the molecular-level, 3D ultrastructure detail provided by cryoET. As such, a correlative approach performed on a given specimen can provide high resolution snapshots of dynamic cellular events. In this article, I review recent advances in correlative light microscopy and cryoET and discuss major findings made available by applying this method. PMID:23962486

Zhang, Peijun

2013-08-17

244

The synthesis, characterization and application of iron oxide nanocrystals in magnetic separations for arsenic and uranium removal  

NASA Astrophysics Data System (ADS)

Arsenic and uranium in the environment are hazardous to human health and require better methods for detection and remediation. Nanocrystalline iron oxides offer a number of advantages as sorbents for water purification and environmental remediation. First, highly uniform and crystalline iron oxide nanocrystals (nMAG) were prepared using thermal decomposition of iron salts in organic solutions; for the applications of interest in this thesis, a central challenge was the adaptation of these conventional synthetic methods to the needs of low infrastructure and economically disadvantaged settings. We show here that it is possible to form highly uniform and magnetically responsive nanomaterials using starting reagents and equipment that are readily available and economical. The products of this approach, termed the 'Kitchen Synthesis', are of comparable quality and effectiveness to laboratory materials. The narrow size distributions of the iron oxides produced in the laboratory synthesis made it possible to study the size-dependence of the magnetic separation efficiency of nanocrystals; generally as the diameter of particles increased they could be removed under lower applied magnetic fields. In this work we take advantage of this size-dependence to use magnetic separation as a tool to separate broadly distributed populations of magnetic materials. Such work makes it possible to use these materials in multiplexed separation and sensing schemes. With the synthesis and magnetic separation studies of these materials completed, it was possible to optimize their applications in water purification and environmental remediation. These materials removed both uranium and arsenic from contaminated samples, and had remarkably high sorption capacities --- up to 12 wt% for arsenic and 30 wt% for uranium. The contaminated nMAG is removed from the drinking water by either retention in a sand column, filter, or by magnetic separation. The uranium adsorption process was also utilized for the enhanced detection of uranium in environmental matrices. By relying on alpha-particle detection in well-formed and dense nMAG films, it was possible to improve soil detection of uranium by more than ten-thousand-fold. Central for this work was a detailed understanding of the chemistry at the iron oxide interface, and the role of the organic coatings in mediating the sorption process.

Mayo, John Thomas

245

3.88 A structure of cytoplasmic polyhedrosis virus by cryo-electron microscopy.  

PubMed

Cytoplasmic polyhedrosis virus (CPV) is unique within the Reoviridae family in having a turreted single-layer capsid contained within polyhedrin inclusion bodies, yet being fully capable of cell entry and endogenous RNA transcription. Biochemical data have shown that the amino-terminal 79 residues of the CPV turret protein (TP) is sufficient to bring CPV or engineered proteins into the polyhedrin matrix for micro-encapsulation. Here we report the three-dimensional structure of CPV at 3.88 A resolution using single-particle cryo-electron microscopy. Our map clearly shows the turns and deep grooves of alpha-helices, the strand separation in beta-sheets, and densities for loops and many bulky side chains; thus permitting atomic model-building effort from cryo-electron microscopy maps. We observed a helix-to-beta-hairpin conformational change between the two conformational states of the capsid shell protein in the region directly interacting with genomic RNA. We have also discovered a messenger RNA release hole coupled with the mRNA capping machinery unique to CPV. Furthermore, we have identified the polyhedrin-binding domain, a structure that has potential in nanobiotechnology applications. PMID:18449192

Yu, Xuekui; Jin, Lei; Zhou, Z Hong

2008-04-30

246

Spin-charge separation in the {ital t}-{ital J} model: Magnetic and transport anomalies  

SciTech Connect

A real spin-charge separation scheme is found based on a saddle-point state of the {ital t}-{ital J} model. In the one-dimensional (1D) case, such a saddle-point reproduces the correct asymptotic correlations at the strong-coupling fixed point of the model. In the two-dimensional (2D) case, the transverse gauge field confining spinon and holon is shown to be gapped at {ital finite} {ital doping} so that a spin-charge deconfinement is obtained for its first time in 2D. The gap in the gauge fluctuation disappears at half-filling limit, where a long-range antiferromagnetic order is recovered at zero temperature and spinons become confined. The most interesting features of spin dynamics and transport are exhibited at finite doping where exotic {ital residual} couplings between spin and charge degrees of freedom lead to systematic anomalies with regard to a Fermi-liquid system. In spin dynamics, a commensurate antiferromagnetic fluctuation with a small, doping-dependent energy scale is found, which is characterized in momentum space by a Gaussian peak at ({pi}/{ital a},{pi}/{ital a}) with a doping-dependent width. This commensurate magnetic fluctuation contributes a non-Korringa behavior for the NMR spin-lattice relaxation rate. There also exists a characteristic temperature scale below thich a pseudogap behavior appears in the spin dynamics. Furthermore, an incommensurate magnetic fluctuation is also obtained at a {ital finite} energy regime. In the transport, a strong-range phase intereference leads to an effective holon Lagrangian which can give rise to a series of interesting phenomena including linear-{ital T} resistivity and a {ital T}{sup 2} Hall angle. We discuss the striking similarities of these theoretical features with those found in the high-{ital T}{sub {ital c}} cuprates and give a consistent picture for the latter. Electronic properties like Fermi surface and superconducting pairing in this framework are also discussed.

Weng, Z.Y.; Sheng, D.N.; Ting, C.S. [Texas Center for Superconductivity and Department of Physics, University of Houston, Houston, Texas 77204-5506 (United States)

1995-07-01

247

A paper-based surface-enhanced resonance Raman spectroscopic (SERRS) immunoassay using magnetic separation and enzyme-catalyzed reaction.  

PubMed

In this study, a novel paper-based SERRS immunoassay based on magnetic separation and alkaline phosphatase (ALP) enzyme catalyzed hydrolysis reaction was developed. By using modified antibodies conjugated to magnetic beads, capture of mouse IgG followed by addition of ALP-labeled antibodies would form a sandwich-like immunoconjugate. After magnetic separation, 5-bromo-4-chloro-3-indolyl phosphate (BCIP), a low SERRS active compound, was added as the substrate for ALP to generate a high SERRS response. Detection was conducted on a silver colloid/PVP/filter paper SERS substrate by spotting a pre-aggregated silver colloid sol onto polyvinyl pyrrolidone (PVP) modified filter paper using a semi-automatic TLC sample applicator. The optimization of the highly SERS active paper-based substrate, dynamic hydrolysis process of BCIP, quantitative detection of IgG, and selectivity of the assay was studied in detail. By taking advantage of magnetic separation in order to decrease the background interference, the selective enzyme reaction involved in producing a highly SERRS active product could detect mouse IgG from 1 to 500 ng mL(-1) with a LOD of 0.33 ng mL(-1). PMID:23486763

Chen, Yuanyuan; Cheng, Hanwen; Tram, Kha; Zhang, Shengfeng; Zhao, Yanhua; Han, Liyang; Chen, Zengping; Huan, Shuangyan

2013-05-01

248

Superconducting open-gradient magnetic separation for the pretreatment of radioactive or mixed waste vitrification feeds. 1997 annual progress report  

SciTech Connect

'Vitrification has been selected as a final waste form technology in the US for long-term storage of high-level radioactive wastes (HLW). However, a foreseeable problem during vitrification in some waste feed streams lies in the presence of elements (e.g., transition metals) in the HLW that may cause instabilities in the final glass product. The formation of spinel compounds, such as Fe{sub 3}O{sub 4} and FeCrO{sub 4}, results in glass phase separation and reduces vitrifier lifetime, and durability of the final waste form. A superconducting open gradient magnetic separation (OGMS) system maybe suitable for the removal of the deleterious transition elements (e.g. Fe, Co, and Ni) and other elements (lanthanides) from vitrification feed streams due to their ferromagnetic or paramagnetic nature. The OGMS systems are designed to deflect and collect paramagnetic minerals as they interact with a magnetic field gradient. This system has the potential to reduce the volume of HLW for vitrification and ensure a stable product. In order to design efficient OGMS and High gradient magnetic separation (HGMS) processes, a fundamental understanding of the physical and chemical properties of the waste feed streams is required. Using HLW simulant and radioactive fly ash and sludge samples from the Savannah River Technology Center, Rocky Flats site, and the Hanford reservation, several techniques were used to characterize and predict the separation capability for a superconducting OGMS system.'

Doctor, R.; Nunez, L. [Argonne National Lab., IL (US); Cicero-Herman, C.A. [Westinghouse Savannah River Co., Aiken, SC (US). Savannah River Technology Center; Ritter, J.A. [Univ. of South Carolina, Columbia, SC (US). Chemical Engineering Dept.; Landsberger, S. [Univ. of Texas, Austin, TX (US). Nuclear Engineering Dept.

1997-01-01

249

Fast characterisation of cell-derived extracellular vesicles by nanoparticles tracking analysis, cryo-electron microscopy, and Raman tweezers microspectroscopy  

PubMed Central

The joint use of 3 complementary techniques, namely, nanoparticle tracking analysis (NTA), cryo-electron microscopy (Cryo-EM) and Raman tweezers microspectroscopy (RTM), is proposed for a rapid characterisation of extracellular vesicles (EVs) of various origins. NTA is valuable for studying the size distribution and concentration, Cryo-EM is outstanding for the morphological characterisation, including observation of vesicle heterogeneity, while RTM provides the global chemical composition without using any exogenous label. The capabilities of this approach are evaluated on the example of cell-derived vesicles of Dictyostelium discoideum, a convenient general model for eukaryotic EVs. At least 2 separate species differing in chemical composition (relative amounts of DNA, lipids and proteins, presence of carotenoids) were found for each of the 2 physiological states of this non-pathogenic microorganism, that is, cell growth and starvation-induced aggregation. These findings demonstrate the specific potency of RTM. In addition, the first Raman spectra of human urinary exosomes are reported, presumably constituting the primary step towards Raman characterisation of EVs for the purpose of human diseases diagnoses.

Tatischeff, Irene; Larquet, Eric; Falcon-Perez, Juan M.; Turpin, Pierre-Yves; Kruglik, Sergei G.

2012-01-01

250

Fast characterisation of cell-derived extracellular vesicles by nanoparticles tracking analysis, cryo-electron microscopy, and Raman tweezers microspectroscopy.  

PubMed

The joint use of 3 complementary techniques, namely, nanoparticle tracking analysis (NTA), cryo-electron microscopy (Cryo-EM) and Raman tweezers microspectroscopy (RTM), is proposed for a rapid characterisation of extracellular vesicles (EVs) of various origins. NTA is valuable for studying the size distribution and concentration, Cryo-EM is outstanding for the morphological characterisation, including observation of vesicle heterogeneity, while RTM provides the global chemical composition without using any exogenous label. The capabilities of this approach are evaluated on the example of cell-derived vesicles of Dictyostelium discoideum, a convenient general model for eukaryotic EVs. At least 2 separate species differing in chemical composition (relative amounts of DNA, lipids and proteins, presence of carotenoids) were found for each of the 2 physiological states of this non-pathogenic microorganism, that is, cell growth and starvation-induced aggregation. These findings demonstrate the specific potency of RTM. In addition, the first Raman spectra of human urinary exosomes are reported, presumably constituting the primary step towards Raman characterisation of EVs for the purpose of human diseases diagnoses. PMID:24009887

Tatischeff, Irène; Larquet, Eric; Falcón-Pérez, Juan M; Turpin, Pierre-Yves; Kruglik, Sergei G

2012-11-21

251

Fabrication of magnetic core@shell Fe oxide@Au nanoparticles for interfacial bioactivity and bio-separation.  

PubMed

The immobilization of proteins on gold-coated magnetic nanoparticles and the subsequent recognition of the targeted proteins provide an effective means for the separation of proteins via application of a magnetic filed. A key challenge is the ability to fabricate such nanoparticles with the desired core-shell nanostructure. In this article, we report findings of the fabrication and characterization of gold-coated iron oxide (Fe2O3 and Fe3O4) core@shell nanoparticles (Fe oxide@Au) toward novel functional biomaterials. A hetero-interparticle coalescence strategy has been demonstrated for fabricating Fe oxide@Au nanoparticles that exhibit controllable sizes ranging from 5 to 100 nm and high monodispersity. Composition and surface analyses have proven that the resulting nanoparticles consist of the Fe2O3 core and the Au shell. The magnetically active Fe oxide core and thiolate-active Au shell were shown to be viable for exploiting the Au surface protein-binding reactivity for bioassay and the Fe oxide core magnetism for magnetic bioseparation. These findings are entirely new and could form the basis for fabricating magnetic nanoparticles as biomaterials with tunable size, magnetism, and surface binding properties. PMID:17629315

Park, Hye-Young; Schadt, Mark J; Wang, Lingyan; Lim, I-Im Stephanie; Njoki, Peter N; Kim, Soo Hong; Jang, Min-Young; Luo, Jin; Zhong, Chuan-Jian

2007-07-13

252

Magnetic separation of CD14+ cells using antibody binding with protein A expressed on bacterial magnetic particles for generating dendritic cells.  

PubMed

Herein the potential of a highly efficient cell separation system using bacterial magnetic particles expressing protein A (protein A-BacMPs) was demonstrated. Protein A was expressed on BacMPs using the transmembrane proteins Mms13 and MagA as anchor molecules. The evaluations of the numbers of bound antibody molecules and binding capabilities of the protein A-BacMPs using Mms13 indicated that the antibodies were efficiently introduced into protein A-BacMPs using Mms13 in comparison to MagA. In addition, the recovery ratio of the target cells on the magnetic cell separation system was enhanced by using protein A-BacMPs with Mms13. Using positive selection against peripheral blood mononuclear cells, the CD14(+) cells were separated at a purity of more than 99% by protein A-BacMPs using Mms13. Furthermore, in the evaluation of the influence of protein A-BacMPs on the separated cells, the CD14(+) cells separated using protein A-BacMPs and were successfully differentiated into dendritic cells. PMID:17045961

Matsunaga, Tadashi; Takahashi, Masayuki; Yoshino, Tomoko; Kuhara, Motoki; Takeyama, Haruko

2006-10-05

253

Synthesis of orientedly bioconjugated core\\/shell Fe 3O 4@Au magnetic nanoparticles for cell separation  

Microsoft Academic Search

Orientedly bioconjugated core\\/shell Fe3O4@Au magnetic nanoparticles were synthesized for cell separation. The Fe3O4@Au magnetic nanoparticles were synthesized by reducing HAuCl4 on the surfaces of Fe3O4 nanoparticles, which were further characterized in detail by TEM, XRD and UV–vis spectra. Anti-CD3 monoclonal antibody was orientedly bioconjugated to the surface of Fe3O4@Au nanoparticles through affinity binding between the Fc portion of the antibody

Yi-Ran Cui; Chao Hong; Ying-Lin Zhou; Yue Li; Xiao-Ming Gao; Xin-Xiang Zhang

254

Cell separation by antibody-coupled magnetic microspheres and their application in conjunction with monoclonal HLA-antibodies.  

PubMed

The modification and efficiency of a technique for cell separation is described. This technique combines the specificity of serologic reactions with the strength and physical selectivity of a magnetic field. A monoclonal HLA-BW 6 antibody was coupled to 100 nm diameter Fe3O4 containing albumin microspheres via surface-incorporated St. aureus Protein-A. The mixture of HLA-BW 6 and -BW 4 human peripheral blood lymphocytes was incubated with these immunomicropheres and applied to a glass column located in a magnetic field. Only HLA-BW 4 lymphocytes passed through the column and were collected. The recovered cells were 97% viable. PMID:7276069

Kandzia, J; Anderson, M J; Müller-Ruchholtz, W

1981-01-01

255

Microcystin-LR removal from aqueous solutions using a magnetically separable N-doped TiO2 nanocomposite under visible light irradiation.  

PubMed

The performance of magnetically separable N-doped TiO2 was found to be significantly improved when compared with non-magnetic N-doped TiO2 for the removal of cyanotoxin microcystin-LR from aqueous medium. The observed enhanced photocatalytic activity may be related to the presence of ferrite nanoparticles in the composition of the magnetically separable composite N-doped TiO2. PMID:24045651

Pelaez, Miguel; Baruwati, Babita; Varma, Rajender S; Luque, Rafael; Dionysiou, Dionysios D

2013-10-01

256

Simple analytical model for the magnetophoretic separation of superparamagnetic dispersions in a uniform magnetic gradient.  

PubMed

Magnetophoresis--the motion of magnetic particles under applied magnetic gradient--is a process of great interest in novel applications of magnetic nanoparticles and colloids. In general, there are two main different types of magnetophoresis processes: cooperative magnetophoresis (a fast process enhanced by particle-particle interactions) and noncooperative magnetophoresis (driven by the motion of individual particles in magnetic fields). In the case of noncooperative magnetophoresis, we have obtained a simple analytical solution which allows the prediction of the magnetophoresis kinetics from particle characterization data (size and magnetization). Our comparison with new experimental results shows good quantitative agreement. In addition, we show the existence of a universal curve onto which all experimental results should collapse after proper rescaling. The range of applicability of the analytical solution is discussed in light of the predictions of a magnetic aggregation model [Soft Matter 7, 2336 (2011)]. PMID:21928989

Andreu, J S; Camacho, J; Faraudo, J; Benelmekki, M; Rebollo, C; Martínez, Ll M

2011-08-22

257

Simple analytical model for the magnetophoretic separation of superparamagnetic dispersions in a uniform magnetic gradient  

NASA Astrophysics Data System (ADS)

Magnetophoresis—the motion of magnetic particles under applied magnetic gradient—is a process of great interest in novel applications of magnetic nanoparticles and colloids. In general, there are two main different types of magnetophoresis processes: cooperative magnetophoresis (a fast process enhanced by particle-particle interactions) and noncooperative magnetophoresis (driven by the motion of individual particles in magnetic fields). In the case of noncooperative magnetophoresis, we have obtained a simple analytical solution which allows the prediction of the magnetophoresis kinetics from particle characterization data (size and magnetization). Our comparison with new experimental results shows good quantitative agreement. In addition, we show the existence of a universal curve onto which all experimental results should collapse after proper rescaling. The range of applicability of the analytical solution is discussed in light of the predictions of a magnetic aggregation model [Soft MatterJAPIAU1744-683X10.1039/c0sm01424a 7, 2336 (2011)].

Andreu, J. S.; Camacho, J.; Faraudo, J.; Benelmekki, M.; Rebollo, C.; Martínez, Ll. M.

2011-08-01

258

Linear expansion, phase separation, and magnetic inhomogeneities in La0.92Ca0.08MnO3  

NASA Astrophysics Data System (ADS)

A relation of the thermal expansion with magnetic and magnetotransport properties has been revealed in La0.92Ca0.08MnO3 single crystals in the paramagnetic state. The magnetotransport and lattice properties and the specific features in the neutron scattering characteristics of the La0.92Ca0.08MnO3 single crystals have been explained by the phase separation in the paramagnetic state into magnetic inhomogeneities (clusters) with short-range (˜10 Å) and long-range (>102 Å) orders. The performed investigations have demonstrated that the clusters are closely related to the crystal lattice and that the magnetic inhomogeneities in the paramagnetic region are correlated to T ˜ 250-300 K ? TC.

Solin, N. I.; Kazantsev, V. A.

2013-09-01

259

Synthesis and performance of novel magnetically separable nanospheres of titanium dioxide photocatalyst with egg-like structure  

NASA Astrophysics Data System (ADS)

A magnetically separable photocatalyst TiO2/SiO2/NiFe2O4 (TSN) nanosphere with egg-like structure was prepared by a unique process that combined a liquid catalytic phase transformation method, reverse micelle technique and chemical precipitation means. The prepared photocatalyst shows high photocatalytic activity for the degradation of methyl orange in water. The magnetic property measurements indicate that the photocatalyst possesses a superparamagnetic nature. It can be separated from water when an external magnetic field is added and redispersed into water solution after the external magnetic field is eliminated. It is one of the promising photocatalysts for wastewater treatment. A transmission electron microscope (TEM) and an x-ray diffractometer (XRD) were used to characterize the structure of the TSN photocatalyst. The results indicate that nickel ferrite core nanoparticles were completely encapsulated into monodisperse silica nanospheres as carrier, and titania nanoparticle aggregates were coated onto the surface of SN nanospheres, forming an imperfect TiO2 shell for photocatalysis. The SiO2 layer between the NiFe2O4 core and the TiO2 shell effectively prevents the injection of charges from TiO2 particles to NiFe2O4, which gives rise to an increase in photocatalytic activity. Moreover, the recycled TSN exhibits good repeatability of the photocatalytic activity.

Xu, Shihong; Shangguan, Wenfeng; Yuan, Jian; Chen, Mingxia; Shi, Jianwei; Jiang, Zhi

2008-03-01

260

Detecting particles in cryo-EM micrographs using learned features.  

PubMed

A new learning-based approach is presented for particle detection in cryo-electron micrographs using the Adaboost learning algorithm. The approach builds directly on the successful detectors developed for the domain of face detection. It is a discriminative algorithm which learns important features of the particle's appearance using a set of training examples of the particles and a set of images that do not contain particles. The algorithm is fast (10 s on a 1.3 GHz Pentium M processor), is generic, and is not limited to any particular shape or size of the particle to be detected. The method has been evaluated on a publicly available dataset of 82 cryoEM images of keyhole lympet hemocyanin (KLH). From 998 automatically extracted particle images, the 3-D structure of KLH has been reconstructed at a resolution of 23.2 A which is the same resolution as obtained using particles manually selected by a trained user. PMID:15065673

Mallick, Satya P; Zhu, Yuanxin; Kriegman, David

261

Cryo-electron microscopy of vitrified chromosomes in situ.  

PubMed Central

Chromosomes of metaphase-arrested Chinese hamster ovary (CHO) and HeLa cells were examined in situ, unfixed and unstained, by cryo-electron microscopy. In hydrated, vitrified cryo-sections, chromosomes exhibit a characteristic homogeneous, grainy texture, which, on optical diffraction, gives rise to a broad reflection corresponding to 11 nm. No superstructure or periodic order is discernible. These observations suggest that the chromosome is formed by the compact association of 11 nm filaments, or portions thereof, interacting in a manner akin to the molecules of a liquid. Some implications of the liquid model of chromosome structure are discussed. Images Fig. 1. Fig. 2. Fig. 3. Fig. 4 and 5. Fig. 6.

McDowall, A W; Smith, J M; Dubochet, J

1986-01-01

262

The role of magnetic fields on the membrane-based separation of aqueous electrolyte solutions  

Microsoft Academic Search

Molecular simulations using the method of molecular dynamics have been carried out to examine the role that external magnetic fields can play in the transport of water via reverse osmosis (RO) across membranes. Our results show that magnetic fields can increase the transport rate of water across such membranes significantly. These observations can have an important impact on making RO

S. Murad

2006-01-01

263

Hydration-layer models for cryo-EM image simulation.  

PubMed

To compare cryo-EM images and 3D reconstructions with atomic structures in a quantitative way it is essential to model the electron scattering by solvent (water or ice) that surrounds protein assemblies. The most rigorous method for determining the density of solvating water atoms for this purpose has been to perform molecular-dynamics (MD) simulations of the protein-water system. In this paper we adapt the ideas of bulk-water modeling that are used in the refinement of X-ray crystal structures to the cryo-EM solvent-modeling problem. We present a continuum model for solvent density which matches MD-based results to within sampling errors. However, we also find that the simple binary-mask model of Jiang and Brünger (1994) performs nearly as well as the new model. We conclude that several methods are now available for rapid and accurate modeling of cryo-EM images and maps of solvated proteins. PMID:22609687

Shang, Zhiguo; Sigworth, Fred J

2012-05-17

264

Data quality assessment of CryoSat products  

NASA Astrophysics Data System (ADS)

The main payload of CryoSat is a Ku band pulsewidth limited radar altimeter, called SIRAL (Synthetic interferometric radar altimeter), that transmits pulses at a high pulse repetition frequency thus making the received echoes phase coherent and suitable for azimuth processing. This allows to reach a significantly improved along track resolution with respect to traditional pulse-width limited altimeters. There are three operating modes: low resolution mode (LRM), Synthetic Aperture Radar (SAR) and Synthetic Aperture Radar Interferometric (SARIn). Both the Level 1b and the Level 2 data products are defined depending on the operating mode used by the instrument. However, Level 1b products essentially contain an average echo for each location along the ground track while Level 2 products contains an elevation for each location along the satellite track. In this poster we will detail as first the different data products and then the quality achieved on those products will be described after more than 2 years of operational activity of the CryoSat satellite. In particular, the characteristics of the impulse response function in the two direction, the along track and the across track, will be described in order to verify that the performance are in line with expectation as well as stable over the time. To exploit the stability over the 2 years of mission, the products obtained as outcomes of the reprocessing activity will be exploited, allowing to manage an homogeneous set of data processed with the latest version of the CryoSat IPF.

Scagliola, Michele; Bouzinac, Catherine; Fornari, Marco; Mannan, Rubinder

2013-04-01

265

Cryo Electron Tomography of Herpes Simplex Virus during Axonal Transport and Secondary Envelopment in Primary Neurons  

PubMed Central

During herpes simplex virus 1 (HSV1) egress in neurons, viral particles travel from the neuronal cell body along the axon towards the synapse. Whether HSV1 particles are transported as enveloped virions as proposed by the ‘married’ model or as non-enveloped capsids suggested by the ‘separate’ model is controversial. Specific viral proteins may form a recruitment platform for microtubule motors that catalyze such transport. However, their subviral location has remained elusive. Here we established a system to analyze herpesvirus egress by cryo electron tomography. At 16 h post infection, we observed intra-axonal transport of progeny HSV1 viral particles in dissociated hippocampal neurons by live-cell fluorescence microscopy. Cryo electron tomography of frozen-hydrated neurons revealed that most egressing capsids were transported independently of the viral envelope. Unexpectedly, we found not only DNA-containing capsids (cytosolic C-capsids), but also capsids lacking DNA (cytosolic A-/B-capsids) in mid-axon regions. Subvolume averaging revealed lower amounts of tegument on cytosolic A-/B-capsids than on C-capsids. Nevertheless, all capsid types underwent active axonal transport. Therefore, even few tegument proteins on the capsid vertices seemed to suffice for transport. Secondary envelopment of capsids was observed at axon terminals. On their luminal face, the enveloping vesicles were studded with typical glycoprotein-like spikes. Furthermore, we noted an accretion of tegument density at the concave cytosolic face of the vesicle membrane in close proximity to the capsids. Three-dimensional analysis revealed that these assembly sites lacked cytoskeletal elements, but that filamentous actin surrounded them and formed an assembly compartment. Our data support the ‘separate model’ for HSV1 egress, i.e. progeny herpes viruses being transported along axons as subassemblies and not as complete virions within transport vesicles.

Ibiricu, Iosune; Huiskonen, Juha T.; Dohner, Katinka; Bradke, Frank; Sodeik, Beate; Grunewald, Kay

2011-01-01

266

Cryo-EM modeling by the molecular dynamics flexible fitting method  

PubMed Central

The increasing power and popularity of cryo-electron (cryo-EM) microscopy in structural biology brought about the development of so-called hybrid methods, which permit the interpretation of cryo-EM density maps beyond their nominal resolution in terms of atomic models. The Cryo-EM Modeling Challenge 2010 is the first community effort to bring together developers of hybrid methods as well as cryo-EM experimentalists. Participating in the challenge, the molecular dynamics flexible fitting (MDFF) method was applied to a number of cryo-EM density maps. The results are described here with special emphasis on the use of symmetry-based restraints to improve the quality of atomic models derived from density maps of symmetric complexes; on a comparison of the stereochemical quality of atomic models resulting from different hybrid methods; and on application of MDFF to electron crystallography data.

Chan, Kwok-Yan; Trabuco, Leonardo G.; Schreiner, Eduard; Schulten, Klaus

2012-01-01

267

On a plasma sheath separating regions of oppositely directed magnetic field  

Microsoft Academic Search

Summary  An exact solution of the Vlasov equations is found which describes a layer of plasma confined between two regions of oppositely\\u000a directed magnetic field. The electrons and ions have Maxwellian distributions on the plane where the magnetic field vanishes.\\u000a In the coordinate system, in which the electron and ion drift velocities are equal in magnitude but opposite in direction,\\u000a the

E. G. Harris

1962-01-01

268

Capture and separation of biomolecules using magnetic beads in a simple microfluidic channel without an external flow device.  

PubMed

The use of microfluidic devices and magnetic beads for applications in biotechnology has been extensively explored over the past decade. Many elaborate microfluidic chips have been used in efficient systems for biological assays. However most fail to achieve the ideal point of care (POC) status, as they require larger conventional external devices in conjunction with the microchip. This paper presents a simple technique to capture and separate biomolecules using magnetic bead movement on a microchip without the use of an external flow device. This microchip consisted of two well reservoirs (W1 and W2) connected via a tapered microchannel. Beads were dragged through the microchannel between the two wells at an equivalent speed to a permanent magnet that moved alongside the microchip. More than 95% of beads were transferred from W1 to W2 within 2 min at an average velocity of 0.7 mm s(-1). Enzymatic reactions were employed to test our microchip. Specifically, three assays were performed using the streptavidin coated magnetic beads as a solid support to capture and transfer biomolecules: (1) non-specific adsorption of the substrate, 6-8-difluoro-4-methylumbelliferyl phosphate (DiFMUP), (2) capture of the enzyme, biotinylated alkaline phosphatase (AP), and (3) separation of AP from DiFMUP. Our non-specific adsorption assay indicated that the microchip was capable of transferring the beads with less than 0.002% carryover of DiFMUP. Our capture assay indicated efficient capture and transfer of AP with beads to W2 containing DiFMUP, where the transferred AP converted 100% of DiFMUP to DiFMU within 15 minutes. Our separation assay showed effective separation of AP from DiFMUP and elucidated the binding capacity of the beads for AP. The leftover unbound AP in W1 converted 100% of DiFMUP within 10 minutes and samples with less than the full bead capacity of AP (i.e. all AP was transferred) did not convert any of the DiFMUP. The immobilization of AP on the bead surface resulted in 32% reduced enzymatic speed compared to that of free AP in solution, as a result of altered protein conformation and/or steric hindrance of the catalytic site. Overall, this microfluidic platform was established as a simple, efficient and effective approach for separating biomolecules without any flow apparatus. PMID:24051541

Wang, Jingjing; Morabito, Kenneth; Erkers, Tom; Tripathi, Anubhav

2013-09-30

269

Improved Peak Capacity for Capillary Electrophoretic Separations of Enzyme Inhibitors with Activity-Based Detection Using Magnetic Bead Microreactors  

PubMed Central

A technique for separating and detecting enzyme inhibitors was developed using capillary electrophoresis with an enzyme microreactor. The on-column enzyme microreactor was constructed using NdFeB magnet(s) to immobilize alkaline phosphatase-coated superparamagnetic beads (2.8 ?m diameter) inside a capillary before the detection window. Enzyme inhibition assays were performed by injecting a plug of inhibitor into a capillary filled with the substrate, AttoPhos. Product generated in the enzyme microreactor was detected by laser-induced fluorescence. Inhibitor zones electrophoresed through the capillary, passed through the enzyme microreactor, and were observed as negative peaks due to decreased product formation. The goal of this study was to improve peak capacities for inhibitor separations relative to previous work, which combined continuous engagement electrophoretically mediated microanalysis (EMMA) and transient engagement EMMA to study enzyme inhibition. The effects of electric field strength, bead injection time and inhibitor concentrations on peak capacity and peak width were investigated. Peak capacities were increased to ?20 under optimal conditions of electric field strength and bead injection time for inhibition assays with arsenate and theophylline. Five reversible inhibitors of alkaline phosphatase (theophylline, vanadate, arsenate, L-tryptophan and tungstate) were separated and detected to demonstrate the ability of this technique to analyze complex inhibitor mixtures.

Yan, Xiaoyan; Gilman, S. Douglass

2010-01-01

270

New high performance hybrid magnet plates for DNA separation andbio-technology applications  

SciTech Connect

A new class of magnet plates for biological and industrial applications has recently been developed at the D.O.E. Joint Genome Institute and Lawrence Berkeley National Laboratory (JGI/LBNL). These devices utilize hybrid technology that combines linear permanent magnet material and ferromagnetic material to produce significantly higher fields and gradients than currently available commercial magnet plates. These hybrid structures incorporate ferromagnetic poles that can be easily shaped to produce complex field distributions for specialized applications. The higher maximum fields and strong gradients of the hybrid structures result in greater holding forces on magnetized targets that are being processed as well as faster draw-down. Current development versions of these magnet plates have exhibited maximum fields in excess of 9000.0 Gauss. The design of these structures is easily scalable to allow for field increases to significantly above 1.0 tesla (10000.0gauss). Author's note: 11000.0 Gauss peak fields have been achieved as of January 2005.

Humphries, David; Pollard, Martin; Elkin, Chris; Petermann, Karl; Reiter, Charles; Cepeda, Mario

2004-08-02

271

Interim cryo-cooler/detector report  

SciTech Connect

This report describes development of an electronic system designed to reduce vibration generated by a cryocooler. The diminished vibration makes it practical to use the active cooler to extract heat from a portable gamma ray detector instrument. The system was developed for a Sunpower cryocooler with an integrated counterbalance mass. The overall momentum cancellation approach is also applicable to other similar cryocoolers. The cancellation system is an assembly of several components tailored to accomplish the required vibration reduction with minimum power consumption and volume. It is designed to be powered by a 18--32 Volt battery. Up to ten harmonics of the 58.65 Hz drive frequency are controlled. In addition to the vibration cancellation, the electronic system produces the drive signal for the cryocooler and regulates the cooler temperature. The system employs a sinusoidal drive to reduce the amount of higher harmonic vibration. A digital signal processor (DSP) is used to perform the high speed vibration control. The Texas Instruments TMS320C31 processor is housed on a third-party board. A second board has analog-to-digital (A/D) and digital-to-analog (D/A) converters. The DSP was programmed in C. The physical system consists of two sets of electronics. The first is housed in a case that is separate from the detector unit.

Neufeld, K.; Ruhter, W. [Lawrence Livermore National Lab., CA (United States); Anderson, E. [CSA Engineering, Inc., Palo Alto, CA (United States)

1995-04-19

272

Phase separation and frustrated square lattice magnetism of Na1.5VOPO4F0.5  

NASA Astrophysics Data System (ADS)

Crystal structure, electronic structure, and magnetic behavior of the spin-(1)/(2) quantum magnet Na1.5VOPO4F0.5 are reported. The disorder of Na atoms leads to a sequence of structural phase transitions revealed by synchrotron x-ray powder diffraction and electron diffraction. The high-temperature second-order ??? transition at 500 K is of the order-disorder type, whereas the low-temperature ???+?' transition around 250 K is of the first order and leads to a phase separation toward the polymorphs with long-range (?) and short-range (?') order of Na. Despite the complex structural changes, the magnetic behavior of Na1.5VOPO4F0.5 probed by magnetic susceptibility, heat capacity, and electron spin resonance measurements is well described by the regular frustrated square lattice model of the high-temperature ?-polymorph. The averaged nearest-neighbor and next-nearest-neighbor couplings are J¯1?-3.7 K and J¯2?6.6 K, respectively. Nuclear magnetic resonance further reveals the long-range ordering at TN=2.6 K in low magnetic fields. Although the experimental data are consistent with the simplified square-lattice description, band structure calculations suggest that the ordering of Na atoms introduces a large number of inequivalent exchange couplings that split the square lattice into plaquettes. Additionally, the direct connection between the vanadium polyhedra induces an unusually strong interlayer coupling having effect on the transition entropy and the transition anomaly in the specific heat. Peculiar features of the low-temperature crystal structure and the relation to isostructural materials suggest Na1.5VOPO4F0.5 as a parent compound for the experimental study of tetramerized square lattices as well as frustrated square lattices with different values of spin.

Tsirlin, A. A.; Nath, R.; Abakumov, A. M.; Furukawa, Y.; Johnston, D. C.; Hemmida, M.; Krug von Nidda, H.-A.; Loidl, A.; Geibel, C.; Rosner, H.

2011-07-01

273

A Magnetically Separable, Highly Stable Enzyme System Based on Nanocomposites of Enzymes and Magnetic Nanoparticles Shipped in Hierarchically Ordered, Mesocellular, Mesoporous Silica  

SciTech Connect

Enzymes are versatile nanoscale biocatalysts, and find increasing applications in many areas, including organic synthesis[1-3] and bioremediation.[4-5] However, the application of enzymes is often hampered by the short catalytic lifetime of enzymes and by the difficulty in recovery and recycling. To solve these problems, there have been a lot of efforts to develop effective enzyme immobilization techniques. Recent advances in nanotechnology provide more diverse materials and approaches for enzyme immobilization. For example, mesoporous materials offer potential advantages as a host of enzymes due to their well-controlled porosity and large surface area for the immobilization of enzymes.[6,7] On the other hand, it has been demonstrated that enzymes attached on magnetic iron oxide nanoparticles can be easily recovered using a magnet and recycled for iterative uses.[8] In this paper, we report the development of magnetically-separable and highly-stable enzyme system by the combined use of two different kinds of nanostructured materials: magnetic nanoparticles and mesoporous silica.

Kim, Jungbae; Lee, Jinwoo; Na, Hyon Bin; Kim, Byoung Chan; Youn, Jongkyu; Kwak, Ja Hun; Moon, Karam; Lee, Eunwoong; Kim, Jaeyun; Park, Jongnam; Dohnalkova, Alice; Park, Hyun-Gyu; Gu, Man Bock; Chang, Ho Nam; Grate, Jay W.; Hyeon, Taeghwan

2005-12-01

274

Inactivation and magnetic separation of bacteria from liquid suspensions using electrosprayed and nonelectrosprayed nZVI particles: observations and mechanisms.  

PubMed

Here, nonelectrosprayed nanoscale zerovalent iron (NE-nZVI), electrosprayed nZVI (E-nZVI) and preoxidized nZVI (O-nZVI) particles were applied to inactivating Bacillus subtilis, Escherichia coli as well as bacteria in various wastewater samples. In addition, magnetic separation was applied to the mixture of 0.2 mL bacterial sample and 1.8 mL E-nZVI or NE-nZVI suspensions. Bacterial concentrations and optical density of the supernatants were analyzed using culturing, optical adsorption and qPCR tests. In general, for wastewater samples the inactivations were shown to range from 1-log to 3-log. PCR-DGGE analysis indicated that no gene mutation occurred when bacteria were treated with nZVI. Using magnetic separation, significant physical removals, revealed as a function of nZVI type (NE-,E- and O-nZVI) and bacterial concentration, up to 6-log were obtained. E-nZVI and NE-nZVI were shown to react differently with B. subtilis and E. coli, although exhibiting similar inactivation rates. qPCR tests detected higher amount of DNA in the supernatants from mixing E. coli with NE-nZVI, but less for E-nZVI. However, the opposite was observed with B. subtilis. Our data together with optical adsorption analysis suggested that the inactivation and magnetic separation mainly depend on Fe(0)/Fe(3)O(4) shell compositions, the type of bacteria (aerobic and anaerobic) and their concentrations. PMID:22264123

Chen, Qi; Gao, Min; Li, Jing; Shen, Fangxia; Wu, Yan; Xu, Zhenqiang; Yao, Maosheng

2012-02-06

275

Glassy ferromagnetism and magnetic phase separation in La1-xSrxCoO3  

Microsoft Academic Search

We present the results of a comprehensive investigation of the dc magnetization, ac susceptibility, and magnetotransport properties of the glassy ferromagnet La1-xSrxCoO3. The compositions studied span the range from the end-member LaCoO3 (x=0.0) through to x=0.7. These materials have attracted attention recently, primarily due to the spin-state transition phenomena in LaCoO3 and the unusual nature of the magnetic ground state

J. Wu; C. Leighton

2003-01-01

276

Utilization of magnetic hydrogels in the separation of toxic metal ions from aqueous environments  

Microsoft Academic Search

We report the synthesis of poly(2-acrylamido-2-methyl-1-propansulfonic acid-co-vinylimidazole), p(AMPS-c-VI) hydrogels from various amounts of 2-acrylamido-2-methyl-1-propansulfonic acid (AMPS) and N-vinylimidazole (VI) monomers by photo-polymerization technique. Hydrogel composites with magnetic properties were synthesized in situ by incorporating Fe(II) and Fe(III) ions into p(AMPS-c-VI) hydrogels network and then reducing them with alkaline solution. Hydrogels swellings were performed for both bare and magnetic hydrogels. The

Ozgur Ozay; Sema Ekici; Yakup Baran; Senol Kubilay; Nahit Aktas; Nurettin Sahiner

2010-01-01

277

Removal of Radioactive Heavy Metal Ions From Solution by Superconducting High-Gradient Magnetic Separation With Schwertmannite and Zirconium-Ferrite Adsorbents  

Microsoft Academic Search

Schwertmannite, i.e. iron oxyhydroxysulfate and zirconium-ferrite particles are excellent adsorbents for uranium ions. The magnetic separation characteristics for removal of radioactive ions, i.e. uranium and radium ions, from solution with the adsorbents of synthesized schwertmannite and the zirconium-ferrite particles have been studied. By a 10 tesla superconducting high-gradient magnetic separator, 10 ppb uranium ions in sample solution could be reduced

Kenji Nishimura; Osuke Miura; Daisuke Ito; Yasumichi Tsunasima; Yukio Wada

2009-01-01

278

Separation of fields and 3D inversion of gravity and magnetic data for the Thuringian Basin, Germany  

NASA Astrophysics Data System (ADS)

We have developed a new algorithm for the 3D inversion of potential field data, and we have applied it to gravity and magnetic data from the Thuringian Basin in Mid-Germany to obtain additional constraints for the basin structure. A detailed structural model is an essential boundary condition for models of fluid transport, one of the central goals of the INFLUINS project. Our inversion approach separates the sources (i) in depth using upward and downward continuation, (ii) in the lateral direction by means of approximation with a field generated by 3D line segments, and (iii) according to the density and magnetization contrast on the basis of a pseudo-gravity calculation. Potential field anomalies are modeled either as depth variations of a density interface, or as restricted 3D bodies. We have inverted gravity and magnetic data from the Thuringian Basin for short, intermediate and long wavelengths separately. We assume that the intermediate wavelengths are generated by anomalies in the crystalline basement (~10 km depth), while the short wavelength structure is caused by the variable thickness and structure of the basin sediments. Our 3D model for the main intermediate sources includes three low-density bodies that we interpret as granitic intrusions, and a density interface with topography within the crystalline basement. A significant arc-shaped anomaly, visible both in gravity and in magnetic data, is modeled as an uplift of the crystalline crust. More detailed models for the Tannrodaer anticline are indicative of salt tectonics: the corresponding 3D model includes an uplift of Bundsandstein and a salt deposit. We are currently working on including further constraints on the basin structure from a recently acquired reflection seismic survey.

Prutkin, Ilya; Bleibinhaus, Florian; Jahr, Thomas

2013-04-01

279

Photocatalytic degradation of methylene blue by magnetically separable BiVO4 supported on Fe3O4 nanoparticles  

Microsoft Academic Search

Non-titania photocatalyst BiVO4 was supported on SiO2-coated Fe3O4 particles in order to solve the problems of photocatalyst recovery and reuse. The prepared photocatalyst BiVO4\\/SiO2\\/Fe3O4 (BiVO4\\/SFN) was proved to be nano-sized (less than 10 nm) by TEM characterization. The superparamagnetism of BiVO4\\/SFN was confirmed by a vibrating sample magnetometer (VSM). The photocatalyst can be easily separated experimentally by an external magnetic

Guoting Li; Gangfu Song; Jing Chen; Meiya Zhu; P. K. Wong

2010-01-01

280

Experience in using separators based on rare-earth permanent magnets to enrich nonmetalliferous materials  

Microsoft Academic Search

?rga NPF is the leading manufacturer of rare-earth permanent magnets and equipment based on them. When used for enriching\\u000a the initial materials for making glass such equipment sharply reduces the Fe2O3 content in the initial materials and thereby improves the quality of the manufactured glass articles.

S. V. Kotunov; A. V. Vlasko

2007-01-01

281

Entanglement evolution for excitons of two separate quantum dots in a cavity driven by magnetic field  

Microsoft Academic Search

The time evolution of entanglement for excitons in two quantum dots embedded in a single mode cavity is studied in a ``spin-boson'' regime. It is found that although with the dissipation from the boson mode, the excitons in the two quantum dots can be entangled by only modulating their energy bias $\\\\epsilon$ under the influence of external driving magnetic field.

Jun Jing; Z. G. Lü; H. R. Ma

2006-01-01

282

Calculating Separate Magnetic Free Energy Estimates for Active Regions Producing Multiple Flares: NOAA AR11158  

NASA Astrophysics Data System (ADS)

It is well known that photospheric flux emergence is an important process for stressing coronal fields and storing magnetic free energy, which may then be released during a flare. The Helioseismic and Magnetic Imager (HMI) on board the Solar Dynamics Observatory (SDO) captured the entire emergence of NOAA AR 11158. This region emerged as two distinct bipoles, possibly connected underneath the photosphere, yet characterized by different photospheric field evolutions and fluxes. The combined active region complex produced 15 GOES C-class, two M-class, and the X2.2 Valentine's Day Flare during the four days after initial emergence on 2011 February 12. The M and X class flares are of particular interest because they are nonhomologous, involving different subregions of the active region. We use a Magnetic Charge Topology together with the Minimum Current Corona model of the coronal field to model field evolution of the complex. Combining this with observations of flare ribbons in the 1600 Å channel of the Atmospheric Imaging Assembly on board SDO, we propose a minimization algorithm for estimating the amount of reconnected flux and resulting drop in magnetic free energy during a flare. For the M6.6, M2.2, and X2.2 flares, we find a flux exchange of 4.2 × 1020 Mx, 2.0 × 1020 Mx, and 21.0 × 1020 Mx, respectively, resulting in free energy drops of 3.89 × 1030 erg, 2.62 × 1030 erg, and 1.68 × 1032 erg.

Tarr, Lucas; Longcope, Dana; Millhouse, Margaret

2013-06-01

283

Palladium nanoparticle supported on cobalt ferrite: an efficient magnetically separable catalyst for ligand free Suzuki coupling  

Microsoft Academic Search

Synthesis of Pd nanoparticle supported on cobalt ferrite magnetic nanoparticles has been achieved by direct addition of Pd nanoparticles during synthesis of cobalt ferrite nanoparticles by ultrasound assisted co-precipitation in absence of any surface stabilizers or capping agent. The catalytic performance of the Pd incorporated cobalt ferrite nanoparticles was examined in Suzuki coupling reaction in ethanol under ligand free condition.

Kula Kamal Senapati; Subhasish Roy; Chandan Borgohain; Prodeep Phukan

284

Self-assembly molecularly imprinted polymers of 17?-estradiol on the surface of magnetic nanoparticles for selective separation and detection of estrogenic hormones in feeds  

Microsoft Academic Search

This paper reports a surface molecular self-assembly strategy for molecular imprinting on magnetic nanoparticles for selective separation and detection of estrogens in feeds. First, ?-methacryloxypropyltrimethoxysilane (MEMO) was successfully assembled at the surface magnetic nanoparticles through simple free radical polymerization, and subsequently, the copolymerization was further assembled between methacrylic acid (MAA) and ethylene glycol dimethacrylate (EGDMA) in the presence of templates

Shu Wang; Yun Li; Meijuan Ding; Xiaoli Wu; Jinhui Xu; Ruoyu Wang; Tingting Wen; Wenyu Huang; Ping Zhou; Kunfang Ma; Xuemin Zhou; Shuhu Du

2011-01-01

285

Cryo-electron tomography of microtubule-kinesin motor complexes  

PubMed Central

Microtubules complexed with molecular motors of the kinesin family or non-motor microtubule associated proteins (MAPs) such as tau or EB1 have been the subject of cryo-electron microcopy based 3-D studies for several years. Most of these studies that targeted complexes with intact microtubules have been carried out by helical 3-D reconstruction, while few were analyzed by single particle approaches or from 2-D crystalline arrays. Helical reconstruction of microtubule-MAP or motor complexes has been extremely successful but by definition, all helical 3-D reconstruction attempts require perfectly helical assemblies, which present a serious limitation and confine the attempts to 15- or 16-protofilament microtubules, microtubule configurations that are very rare in nature. The rise of cryo-electron tomography within the last few years has now opened a new avenue towards solving 3-D structures of microtubule-MAP complexes that do not form helical assemblies, most importantly for the subject here, all microtubules that exhibit a lattice seam. In addition, not all motor domains or MAPs decorate the microtubule surface regularly enough to match the underlying microtubule lattice, or they adopt conformations that deviate from helical symmetry. Here we demonstrate the power and limitation of cryo-electron tomography using two kinesin motor domains, the monomeric Eg5 motor domain, and the heterodimeric Kar3Vik1 motor. We show here that tomography does not exclude the possibility of post-tomographic averaging when identical subvolumes can be extracted from tomograms and in both cases we were able to reconstruct 3-D maps of conformations that are not possible to obtain using helical or other averaging-based methods.

Cope, Julia; Gilbert, Susan; Rayment, Ivan; Mastronarde, David

2010-01-01

286

Sample preparation induced artifacts in cryo-electron tomographs  

PubMed Central

We investigated the effects of sample preparation and of the exposure to an electron beam on particles in cryo-electron tomographs. Various virus particles with icosahedral symmetry were examined, allowing a comparison of symmetrically related components that should be identical in structure but might be affected differently by these imaging artifacts. Comparison of tomographic reconstructions with previously determined structures established by an independent method showed that neither freezing nor electron beam exposure produced a significant amount of shrinkage along the z axis (thickness). However, we observed damage to regions of the particles located close to the surface of the vitreous ice.

Plevka, P.; Battisti, A.J.; Winkler, D.C.; Tars, K.; Holdaway, H.A.; Bator, C.M.; Rossmann, M.G.

2012-01-01

287

Beam Breakup Studies for New Cryo-Unit  

SciTech Connect

In this paper, we report the numerical simulations of cumulative beam breakup studies for a new cryo-unit for booster design at Jefferson lab. The system consists of two 1-cell and one 7-cell superconducting RF cavities. Combining two 1-cell into a 2-cell together with a 7-cell is also an option. Simulations have been performed using the 2-dimensional time-domain code. The 1-cell+1-cell+7-cell combination confirms beam stability, however, the arrangement 2-cell+7-cell shows instability.

S. Ahmed, I. Shin, R. Kazimi, F. Marhauser ,F. Hannon ,G. Krafft ,B. Yunn ,A. Hofler

2011-03-01

288

The long-term storage of cryo-preserved materials  

NASA Astrophysics Data System (ADS)

Were traces of oestrogen present in veal ten years ago, or has it been used for only a short time very recently? There is no scientist who can answer this question, even with the most advanced analytical techniques. This is because unchanged reference specimens from ten years ago are not available. The Cryo-Bank-Krefeld was set up in West Germany at the beginning of 1980, offering facilities for the storage of all types of substances for posterity by preservation with liquid nitrogen.

Thoma, K.

289

Separation and characterization of alkyl phenol formaldehyde resins demulsifier by adsorption chromatography, gel permeation chromatography, infrared spectrometry and nuclear magnetic resonance spectroscopy  

Microsoft Academic Search

This paper deals with the separation and characterization of alkyl phenol formaldehyde resins demulsifier by infrared spectrometry and nuclear magnetic resonance spectroscopy after separation of the different surfactants and low molecular additives by adsorption chromatography. Firstly, the types of surfactants are identified by methylene blue chloride–chloroform test method and the elemental analysis such as Ca, K, Mg, Na, P, S

Jinxin Li; Jinjun Zhang; Haijun Yang; Yongcheng Ning

2006-01-01

290

Negative ion beam production by a microwave ion source equipped with a magnetically separated double plasma cell system  

NASA Astrophysics Data System (ADS)

Filamentless negative ion beam production was investigated with a compact microwave ion source (2.45 GHz). One of the key points for negative ion production is the magnetic configuration. A magnetic filter field to lower electron temperature was generated in a negative ion production cell, which was shielded magnetically from a discharge cell with a magnetic field to couple microwave to plasma. Production of H- beam was studied with this source. H- was extracted through a grid slit (2×16 mm2) from plasma and accelerated to 20-40 keV. H- beam current was measured with a Faraday cup after magnetic mass separation. Continuous H- beam current of 73 ?A (0.23 mA/cm2) was obtained with a magnetron power of 700 W. H- beam current was increased around 1.4 times by adding Xe gas to the H2 gas. Other negative ion species, which have a potential for applications to industrial ion beam processing with little charge-up problem, were also investigated. Carbon and hydrocarbon negative ion beams were produced using boron alkoxide (B(OCH3)3) and methane. C2H2- beams (22 ?A) were obtained with the alkoxide. C2-(1.6 ?A), C2H-(2.3 ?A), C2H2-(0.6 ?A), and H-(6.9 ?A) beams were produced with methane. SiF4 and BF3 were used to generate F-, Si-, SiF3- and B- beams. Beam currents of these ion species were 17, 0.25, 1.5, and 0.03 ?A, respectively.

Tanaka, M.; Amemiya, K.

2000-02-01

291

Nitride Fuel Development Using Cryo-Process Technique. Space Nuclear Conference 2007.  

National Technical Information Service (NTIS)

A new cryo-process technique has been developed for the fabrication of advanced fuel for nuclear systems. The process uses a new cryo-processing technique whereby small, porous microspheres (<2000 ..m) are formed from sub-micron oxide powder. A simple aqu...

A. E. Erickson B. O'Brien W. E. Windes

2007-01-01

292

Synthesis of magnetically separable Sn doped magnetite\\/silica core–shell structure and photocatalytic property  

Microsoft Academic Search

Sn doped Fe3O4\\/SiO2 core–shell structures with the magnetic and photocatalytic properties have been successfully synthesized using Fe3O4 microspheres as the precursor. The morphology, phase and structure of the bifunctional products were investigated by X-ray powder diffraction, transmission electron microscopy, selected-area electron diffraction, high-resolution transmission electron microscopy, energy dispersive spectroscopy, and scanning electron microscopy. The effects of the amount and hydrolysis

Wei-Wei Wang; Jia-Liang Yao

2010-01-01

293

Screening of cyclodextrins by nuclear magnetic resonance for the design of chiral capillary electrophoresis separations  

Microsoft Academic Search

High-field one-dimensional (1D) and two-dimensional (2D) nuclear magnetic resonance (NMR) spectroscopy and capillary electrophoresis (CE) are examined to investigate the process of chiral recognition occurring between different cyclodextrins (CDs) and the racemic anti-schistosomiasis drug, oxamniquine. Five neutral CDs (?-CD, ?-CD, ?-CD, hydroxypropyl-?-CD and hydroxyethyl-?-CD) and two anionic CDs, carboxymethyl-?-CD (CM-?-CD) and sulphobutyl ether-?-CD (SBE-?-CD) were selected for these NMR and

Paul K Owens; Anthony F Fell; Michael W Coleman; John C Berridge

1998-01-01

294

Entanglement evolution for excitons of two separate quantum dots in a cavity driven by magnetic field  

Microsoft Academic Search

The time evolution of entanglement for excitons in two quantum dots embedded\\u000ain a single mode cavity is studied in a ``spin-boson'' regime. It is found that\\u000aalthough with the dissipation from the boson mode, the excitons in the two\\u000aquantum dots can be entangled by only modulating their energy bias $\\\\epsilon$\\u000aunder the influence of external driving magnetic field.

Jun Jing; Z. G. Lu; H. R. Ma

2006-01-01

295

PDMAEMA-Grafted Core-Shell-Corona Particles for Nonviral Gene Delivery and Magnetic Cell Separation.  

PubMed

Monodisperse, magnetic nanoparticles as vectors for gene delivery were successfully synthesized via the grafting-from approach. First, oleic acid stabilized maghemite nanoparticles (?-Fe2O3) were encapsulated with silica utilizing a reverse microemulsion process with simultaneous functionalization with initiating sites for atom transfer radical polymerization (ATRP). Polymerization of 2-(dimethylamino)ethyl methacrylate (DMAEMA) from the core-shell nanoparticles led to core-shell-corona hybrid nanoparticles (?-Fe2O3@silica@PDMAEMA) with an average grafting density of 91 polymer chains of DPn = 540 (PDMAEMA540) per particle. The permanent attachment of the arms was verified by field-flow fractionation. The dual-responsive behavior (pH and temperature) was confirmed by dynamic light scattering (DLS) and turbidity measurements. The interaction of the hybrid nanoparticles with plasmid DNA at various N/P ratios (polymer nitrogen/DNA phosphorus) was investigated by DLS and zeta-potential measurements, indicating that for N/P ? 7.5 the complexes bear a positive net charge and do not undergo secondary aggregation. The hybrids were tested as transfection agents under standard conditions in CHO-K1 and L929 cells, revealing transfection efficiencies >50% and low cytotoxicity at N/P ratios of 10 and 15, respectively. Due to the magnetic properties of the hybrid gene vector, it is possible to collect most of the cells that have incorporated a sufficient amount of magnetic material by using a magnetic activated cell sorting system (MACS). Afterward, cells were further cultivated and displayed a transfection efficiency of ca. 60% together with a high viability. PMID:23889326

Majewski, Alexander P; Stahlschmidt, Ullrich; Jérôme, Valérie; Freitag, Ruth; Müller, Axel H E; Schmalz, Holger

2013-08-12

296

Dual-responsive magnetic core-shell nanoparticles for nonviral gene delivery and cell separation.  

PubMed

We present the synthesis of dual-responsive (pH and temperature) magnetic core-shell nanoparticles utilizing the grafting-from approach. First, oleic acid stabilized superparamagnetic maghemite (?-Fe(2)O(3)) nanoparticles (NPs), prepared by thermal decomposition of iron pentacarbonyl, were surface-functionalized with ATRP initiating sites bearing a dopamine anchor group via ligand exchange. Subsequently, 2-(dimethylamino)ethyl methacrylate (DMAEMA) was polymerized from the surface by ATRP, yielding dual-responsive magnetic core-shell NPs (?-Fe(2)O(3)@PDMAEMA). The attachment of the dopamine anchor group on the nanoparticle's surface is shown to be reversible to a certain extent, resulting in a grafting density of 0.15 chains per nm(2) after purification. Nevertheless, the grafted NPs show excellent long-term stability in water over a wide pH range and exhibit a pH- and temperature-dependent reversible agglomeration, as revealed by turbidimetry. The efficiency of ?-Fe(2)O(3)@PDMAEMA hybrid nanoparticles as a potential transfection agent was explored under standard conditions in CHO-K1 cells. Remarkably, ?-Fe(2)O(3)@PDMAEMA led to a 2-fold increase in the transfection efficiency without increasing the cytotoxicity, as compared to polyethyleneimine (PEI), and yielded on average more than 50% transfected cells. Moreover, after transfection with the hybrid nanoparticles, the cells acquired magnetic properties that could be used for selective isolation of transfected cells. PMID:22296556

Majewski, Alexander P; Schallon, Anja; Jérôme, Valérie; Freitag, Ruth; Müller, Axel H E; Schmalz, Holger

2012-02-22

297

Optimization of Yield in Magnetic Cell Separations Using Nickel Nanowires of Different Lengths  

Microsoft Academic Search

Ferromagnetic nanowires are shown to perform both high yield and high purity single- step cell separations on cultures of NIH-3T3 mouse fibroblast cells. The nanowires are made by electrochemical deposition in nanoporous templates, permitting detailed control of their chemical and physical properties. When added to fibroblast cell cultures, the nanowires are internalized by the cells via the integrin-mediated adhesion pathway.

Anne Hultgren; Monica Tanase; Edward J. Felton; Kiran Bhadriraju; Aliasger K. Salem; Christopher S. Chen; Daniel H. Reich

2005-01-01

298

The GSI projectile fragment separator (FRS): a versatile magnetic system for relativistic heavy ions  

Microsoft Academic Search

The projectile fragment separator FRS designed for research and applied studies with relativistic heavy ions was installed at GSI as a part of the new high-energy SIS\\/ESR accelerator facility. This high-resolution forward spectrometer has been successfully used in first atomic and nuclear physics experiments using neon, argon, krypton, xenon, and gold beams in the energy range from 500 to 2000

H. Geissel; P. Armbruster; K. H. Behr; A. Brünle; K. Burkard; M. Chen; H. Folger; B. Franczak; H. Keller; O. Klepper; B. Langenbeck; F. Nickel; E. Pfeng; M. Pfützner; E. Roeckl; K. Rykaczewski; I. Schall; D. Schardt; C. Scheidenberger; K.-H. Schmidt; A. Schröter; T. Schwab; K. Sümmerer; M. Weber; G. Münzenberg; T. Brohm; H.-G. Clerc; M. Fauerbach; J.-J. Gaimard; A. Grewe; E. Hanelt; B. Knödler; M. Steiner; B. Voss; J. Weckenmann; C. Ziegler; A. Magel; H. Wollnik; J. P. Dufour; Y. Fujita; D. J. Vieira; B. Sherrill

1992-01-01

299

A New Self-Organized Criticality Model of Solar Flaring Using Reconnection at Magnetic Separators  

Microsoft Academic Search

Several authors have proposed solar flare models in the form of cellular automota, sometimes called sandpile models (Lu and Hamilton 1991, Vlahos et al. 1995). Such models are chiefly motivated by the observation that flare-frequency is related to flare-amplitude by a power-law. We propose an alternative derivation for a cellular automoton model, based on reconnection along separators in a complex

E. J. Noonan; D. W. Longcope

1999-01-01

300

Phase Separation and Magnetic Order in K-doped Iron Selenide Superconductor  

Microsoft Academic Search

Alkali-doped iron selenide is the latest member of high Tc superconductor family, and its peculiar characters have immediately attracted extensive attention. We prepared high-quality potassium-doped iron selenide (KxFe2-ySe2) thin films by molecular beam epitaxy and unambiguously demonstrated the existence of phase separation, which is currently under debate, in this material using scanning tunneling microscopy and spectroscopy. The stoichiometric superconducting phase

Wei Li; Hao Ding; Peng Deng; Kai Chang; Canli Song; Ke He; Lili Wang; Xucun Ma; Jiang-Ping Hu; Xi Chen; Qi-Kun Xue

2011-01-01

301

Cryo Electron Tomography of Native HIV-1 Budding Sites  

PubMed Central

The structure of immature and mature HIV-1 particles has been analyzed in detail by cryo electron microscopy, while no such studies have been reported for cellular HIV-1 budding sites. Here, we established a system for studying HIV-1 virus-like particle assembly and release by cryo electron tomography of intact human cells. The lattice of the structural Gag protein in budding sites was indistinguishable from that of the released immature virion, suggesting that its organization is determined at the assembly site without major subsequent rearrangements. Besides the immature lattice, a previously not described Gag lattice was detected in some budding sites and released particles; this lattice was found at high frequencies in a subset of infected T-cells. It displays the same hexagonal symmetry and spacing in the MA-CA layer as the immature lattice, but lacks density corresponding to NC-RNA-p6. Buds and released particles carrying this lattice consistently lacked the viral ribonucleoprotein complex, suggesting that they correspond to aberrant products due to premature proteolytic activation. We hypothesize that cellular and/or viral factors normally control the onset of proteolytic maturation during assembly and release, and that this control has been lost in a subset of infected T-cells leading to formation of aberrant particles.

Carlson, Lars-Anders; de Marco, Alex; Oberwinkler, Heike; Habermann, Anja; Briggs, John A. G.; Krausslich, Hans-Georg; Grunewald, Kay

2010-01-01

302

Golgi apparatus analyzed by cryo-electron microscopy.  

PubMed

In 1898, the Golgi apparatus was discovered by light microscopy, and since the 1950s, the ultrastructure composition is known by electron microscopic investigation. The complex three-dimensional morphology fascinated researchers and was sometimes even the driving force to develop novel visualization techniques. However, the highly dynamic membrane systems of Golgi apparatus are delicate and prone to fixation artifacts. Therefore, the understanding of Golgi morphology and its function has been improved significantly with the development of better preparation methods. Nowadays, cryo-fixation is the method of choice to arrest instantly all dynamic and physiological processes inside cells, tissues, and small organisms. Embedded in amorphous ice, such samples can be further processed by freeze substitution or directly analyzed in their fully hydrated state by cryo-electron microscopy and tomography. Even though the overall morphology of vitrified Golgi stacks is comparable to well-prepared and resin-embedded samples, previously unknown structural details can be observed solely based on their native density. At this point, any further improvement of sample preparation would gain novel insights, perhaps not in terms of general morphology, but on fine structural details of this dynamic organelle. PMID:23954988

Han, Hong-Mei; Bouchet-Marquis, Cedric; Huebinger, Jan; Grabenbauer, Markus

2013-08-18

303

From CryoSat-2 to Sentinel-3 and Beyond  

NASA Astrophysics Data System (ADS)

CryoSat-2 carried into Earth orbit the first altimeter using SAR principles, although similar techniques had been used on earlier Venusian missions. Furthermore, it carries a second antenna and receive chain, and has been very carefully calibrated, allowing interferometry between these antennas. The results of the SAR mode and of the interferometer have met all expectations, with handsome margins. Even before the launch of CryoSat-2 the further development of this concept was underway with the radar for the oceanography mission Sentinel-3. While this radar, named SRAL (SAR Radar Altimeter) does not have the interferometer capability of CryoSat-2's SIRAL (SAR Interferometric Radar Altimeter), it does have a second frequency, to enable direct measurement of the delay induced by the ionospheric electron content. Sentinel-3 will have a sun-synchronous orbit, like ERS and EnviSat, and will have a similar latitudinal range: about 82° north and south, compared to CryoSat's 88°. Sentinel-3 will operate its radar altimeter in the high-resolution SAR mode over coastal oceans and inland water, and will revert to the more classical pulse-width limited mode over the open oceans. The SAR mode generates data at a high rate, so the major limiting factor is the amount of on-board storage. The power consumption is also higher, imposing less critical constraints. For sizing purposes the coastal oceans are defined as waters within 300 km of the continental shorelines. Sentinel-3 is expected to be launched in 2013 and be followed 18 months later by a second satellite of the same design. The next step in the development of this family of radar altimeters is Jason-CS, which will provide Continuity of Service to the existing Jason series of operational oceanography missions. Jason-CS has a very strong heritage from CryoSat but will fly the traditional Jason orbit, which covers latitudes up to 66° from a high altitude of 1330 km. The new radar is called Poseidon-4, to emphasise the connection to Jason, but its concept owes more to Sentinel-3's SRAL. It retains SRAL's dual frequencies and its SAR mode, but adds some further refinements. Most notably, an operating mode in which SAR operations and full performance pulse-width limited mode are available simultaneously, is under study. This would enable the benefits of SAR mode to be achieved over all ocean areas if the volume of data generated could be stored and downlinked to the ground. This problem only becomes tractable if an on-board processing system can be introduced to perform the first level of SAR processing, reducing the data volume by several orders of magnitude. This is also under study. The architecture of the radar has a further improvement, in the extension of digital technology further into the domain of analog radio-frequency electronics. While this is essentially invisible to the scientific user, it will yield an instrument with higher quality and markedly superior stability. The Jason-CS missions (at least two satellites are planned) are currently in a study phase with an implementation decision expected at the end of 2012. The planned launch date for the first mission is 2017.

Francis, R.

2011-12-01

304

Identification of new astatine isotopes using the gas-filled magnetic separator, SASSY  

Microsoft Academic Search

A He-filled on-line mass separator system was built at the SuperHILAC and used to study the fusion products in the reaction ⁵⁶Fe + ¹⁴¹Pr. The new neutron-deficient isotopes ¹⁹⁴At and ¹⁹⁵At were produced in this bombardment as three- and two- neutron-out products, respectively, and were identified by the ..cap alpha..-..cap alpha.. time-correlation technique. The measured ..cap alpha.. energies and half

Yashita

1984-01-01

305

Identification of new astatine isotopes using the gas-filled magnetic separator, Sassy  

Microsoft Academic Search

A He-filled on-line separator system was built at the SuperHILAC and used to study the fusion products in the reaction ⁵⁶Fe + ¹⁴¹Pr. The new neutron-deficient isotopes ¹⁹⁴At and ¹⁹⁵At were produced in this bombardment as three- and two-neutron-out products, respectively, and were identified by the ..cap alpha..-..cap alpha.. time-correlation technique. The measured ..cap alpha.. energies and half lives are

Yashita

1983-01-01

306

Improvement of the separation of tumour cells from peripheral blood cells using magnetic nanoparticles  

NASA Astrophysics Data System (ADS)

Circulating tumour cells are a key challenge in tumour therapy. Numerous approaches are on the way to achieving the elimination of these potential sources of metastasis formation. Antibody-directed magnetic cell sorting is supposed to enrich tumour cells with high selectivity, but low efficiency. The short term application of carboxymethyl dextran (CMD) coated magnetit/maghemit nanoparticles allows the discrimination of tumour cells from leukocytes. In the present work we show that the interaction of CMD nanoparticles is cell-type specific and time dependent. The breast cancer cell line MCF-7 and the CML cell line K-562 are characterized by a rapid and high interaction rate, whereas leukocytes exhibit a decelerated behaviour. The addition of carboxymethyl dextran or glucose stimulated the magnetic labelling of leukocytes. The variation of the degree of substitution of dextran with carboxymethyl groups did not affect the labelling profile of leukocytes and MCF-7 cells. In order to verify the in vitro results, whole blood samples from 13 cancer patients were analysed ex vivo. Incubation of the purified leukocyte fraction with CMD nanoparticles in the presence of low amounts of plasma reduced the overall cell content in the positive fraction. In contrast, the absolute number of residual tumour cells in the positive fraction was 90% of the initial amount.

Schwalbe, M.; Pachmann, K.; Höffken, K.; Clement, J. H.

2006-09-01

307

Phase-separated alloys for bulk exchange-biased permanent magnets  

SciTech Connect

Explorations in the metallurgical synthesis from the melt of bulk permanent magnets with coercivity conferred by the exchange bias mechanism were carried out in a two-phase materials system composed of ferromagnetic FeCo and antiferromagnetic, nominally equiatomic AuMn. Rapid solidification synthesis of composite alloys of nominal composition (Fe{sub 65}Co{sub 35}){sub 100-x}(AuMn){sub x} (x=5, 10, and 15) was carried out. The ribbons possess AuMn and Au{sub 2}Mn spherical phases in a bcc (Fe,Co) matrix with a bimodal size distribution of nanoscaled and micron sizes. Magnetization measurements of the composite confirm an exchange bias effect correlated with a coercivity increase over that of the (Fe,Co) melt-spun base alloy. While the exchange bias effect is small, the enhanced coercivity and shifted hysteresis loop observed in a single sample create a strong argument for coercivity enhancement conferred by the exchange bias interaction between antiferromagnetic and ferromagnetic phases in a bulk melt-spun nanocomposite material.

Lewis, L. H.; Harland, C. L.; McCallum, R. W.; Kramer, M. J.; Dennis, K. W. [Materials Science Department, Brookhaven National Laboratory, Upton, New York 11973-5000 (United States); Ames Laboratory, Department of Materials Science and Engineering, Iowa State University, Ames, Iowa 50011 (United States)

2006-04-15

308

Facile synthesis of porous Fe7Co3/carbon nanocomposites and their applications as magnetically separable adsorber and catalyst support.  

PubMed

A facile co-gelation route has been developed to synthesize novel porous Fe(7)Co(3)/carbon composites with Fe(7)Co(3) nanoparticles embedded in the porous carbon matrix. The sol-gel process of this route simultaneously involves the hydrolysis of tetraethylorthosilicate (TEOS) and the polymerization of furfuryl alcohol (FA) within an ethanol solution containing TEOS, FA, and metal nitrates, which led to the inorganic/organic hybrid xerogel, accompanying metal salts spontaneously captured in the xerogel, mostly in the framework of poly(furfuryl alcohol) (PFA). Compared to the nanocasting route, the advantage of this method is that the formation of silica template and the impregnation of carbon precursor and metal salts were simultaneously carried out in one co-gelation process, which makes the synthesis very simple and eliminates the time-consuming synthesis of the silica template and multistep impregnation process. Different amounts of Fe(7)Co(3) can be introduced into the composites, which led to different pore structures and magnetic properties. The composites have large surface areas (as high as 651.4 m(2)/g) and high saturation magnetizations (as high as 31.2 emu/g). The Fe(7)Co(3)/carbon composites prepared were successfully applied to the removal of dyes from water and catalysis of hydrogenation as efficient magnetically separable adsober and catalyst support. The facile co-gelation route makes the scalable synthesis of magnetic porous carbon possible for application, and it also provides a promising path to the synthesis of nanoscale metal or alloy embedded in the porous carbon materials. PMID:20369845

Wang, Zhongli; Liu, Ruixia; Zhao, Fengyu; Liu, Xiaojuan; Lv, Minfeng; Meng, Jian

2010-06-15

309

A Longitudinal Study of Abnormal Behaviour of Vertical Magnetic Field in Equatorial Stations Separated by 40  

NASA Astrophysics Data System (ADS)

Variations of the geomagnetic componenets at three equatorial stations Ascension Island(7.95S,14.38W),Ad (9.03N,38.77E)and Trivandrum (8.48N,76.94E) are studied using hourly mean values of geo-magnetic componenents.It is shown that the Sq current system have shown a new type of Sq current distribution dierent from those associated with normal or counter electrojet(EEJ) events on 30 July 1995.This abnormal feature described seems to be a rare phenomenon. Both the horizontal and the vertical componenets of the geomagnetic eld at Addis ababa showed ab-normal maximum when compared with neighbouring days. The daily range of EEJ is found to exist in Indian longitudes did not show any correlation with this event.This additional current system could be due to excitation of certain tidal modes.

Thiagarajan, Arunachalam

310

Suppression of magnetic phase separation in epitaxial SrCoOX films  

NASA Astrophysics Data System (ADS)

Using pulsed laser deposition and a unique fast quenching method, we have prepared SrCoOx epitaxial films on SiTiO3 substrates. As electrochemical oxidation increases the oxygen content from x = 2.75 to 3.0, the films tend to favor the discrete magnetic phases seen in bulk samples for the homologous series SrCoO(3-n/8) (n = 0, 1, 2). Unlike bulk samples, 200 nm thick films remain single phase throughout the oxidation cycle. 300 nm films can show two simultaneous phases during deoxidation. These results are attributed to finite thickness effects and imply the formation of ordered regions larger than approximately 300 nm.

Rueckert, F. J.; Nie, Y. F.; Abughayada, C.; Sabok-Sayr, S. A.; Mohottala, H. E.; Budnick, J. I.; Hines, W. A.; Dabrowski, B.; Wells, B. O.

2013-04-01

311

EVIDENCE FOR TWO SEPARATE BUT INTERLACED COMPONENTS OF THE CHROMOSPHERIC MAGNETIC FIELD  

SciTech Connect

Chromospheric fibrils are generally thought to trace out low-lying, mainly horizontal magnetic fields that fan out from flux concentrations in the photosphere. A high-resolution ({approx}0.''1 pixel{sup -1}) image, taken in the core of the Ca II 854.2 nm line and covering an unusually large area, shows the dark fibrils within an active region remnant as fine, looplike features that are aligned parallel to each other and have lengths comparable to a supergranular diameter. Comparison with simultaneous line-of-sight magnetograms confirms that the fibrils are centered above intranetwork areas (supergranular cell interiors), with one end rooted just inside the neighboring plage or strong unipolar network but the other endpoint less clearly defined. Focusing on a particular arcade-like structure lying entirely on one side of a filament channel (large-scale polarity inversion), we find that the total amount of positive-polarity flux underlying this 'fibril arcade' is {approx}50 times greater than the total amount of negative-polarity flux. Thus, if the fibrils represent closed loops, they must consist of very weak fields (in terms of total magnetic flux), which are interpenetrated by a more vertical field that contains most of the flux. This surprising result suggests that the fibrils in unipolar regions connect the network to the nearby intranetwork flux, while the bulk of the network flux links to remote regions of the opposite polarity, forming a second, higher canopy above the fibril canopy. The chromospheric field near the edge of the network thus has an interlaced structure resembling that in sunspot penumbrae.

Reardon, K. P. [Osservatorio Astrofisico di Arcetri, 50125 Firenze (Italy); Wang, Y.-M.; Warren, H. P. [Space Science Division, Naval Research Laboratory, Washington, DC 20375-5352 (United States); Muglach, K., E-mail: kreardon@arcetri.astro.it, E-mail: yi.wang@nrl.navy.mil, E-mail: hwarren@nrl.navy.mil, E-mail: karin.muglach@nasa.gov [NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States)

2011-12-01

312

Microstructural investigation of monoglyceride-water coagel systems by NMR and CryoSEM.  

PubMed

Monoglyceride coagels consist of a network of plate-like crystals and are formed from a swollen gel state (alpha-gel). In order to resolve the transition mechanism, coagels were prepared with monoglycerides that differ in fatty acid composition (monomyristate and palmitate/stearate, respectively). Rheology provided information on kinetics of coagel formation and the strength of the resulting crystal network. From NMR measurements, the surface-to-volume ratio, tortuosity, and dimensionality of the network were obtained. These findings were in line with qualitative and quantitative structural information obtained from CryoSEM. As a model for the behaviour of non-monoglyceride species, the dynamics of (perdeuterated) palmitic acid was monitored in both alpha-gels and coagels. The experimental data support a two-stage mechanism. In the first stage, two-dimensional separation of D- and L-isomers in the monoglyceride bilayers of the alpha-gel occurs. This process depends primarily on lateral diffusion rate of the monoglycerides. Palmitic acid can be accommodated in the alpha-gel bilayer, but in the coagels it is separated into relative mobile and mechanically weak junction zones between the crystal plates. In the second stage of coagel formation, the crystal plates also grow in the third dimension. Both monoglyceride type and concentration determine the kinetics of this process. PMID:15837489

van Duynhoven, John P M; Broekmann, Ilka; Sein, Arjen; van Kempen, Geert M P; Goudappel, Gert-Jan W; Veeman, Wiebren S

2005-05-15

313

Phase separation and oxygen diffusion in electrochemically oxidized La2CuO4+?: A static magnetic susceptibility study  

NASA Astrophysics Data System (ADS)

The compound La2CuO4+? is known to phase separate for 0.01<~?<~0.06 below a temperature Tps~300 K into the nearly stoichiometric antiferromagnetic compound La2CuO4.01-4.02 with Néel temperature TN~250 K, and a metallic oxygen-rich phase La2CuO~=4.06 with superconducting transition temperature Tc~=34 K. We report studies of the superconducting and normal-state static magnetic susceptibility ? of La2CuO4+? samples with 0<~?<=0.11 prepared by electrochemical oxidation or reduction of conventionally synthesized ceramic La2CuO4+?. The upper limit to the miscibility gap at low T is found be ?<~0.065, in agreement with the previous work. The interstitial oxygen diffusion during the phase-separation process was studied using thermal- and magnetic-field history-dependent ?(T,t) measurements versus temperature T and time t as a probe. Phase separation is found to be suppressed by quenching at >~100 K/s and favored by slow cooling at ~0.5 K/min. A large thermal hysteresis of both the normal and superconducting state ?(T) was observed between data obtained after quenching to 5 K and then warming, and data obtained while or after slowly cooling from 300 K, for samples of La2CuO4+? (?~=0.030, 0.044) within the miscibility gap. Quenching reduces Tc by ~=5 K relative to the value (34 K) obtained after slow cooling. A similar decrease is found for La2CuO4.065 which does not phase separate, indicating the importance of oxygen-ordering effects within this single phase. A model for the excess oxygen diffusion is presented, from which the data yield a nearly T-independent activation energy for excess oxygen diffusion of (0.24+/-0.03) eV from 150 to 220 K apart from a possible anomaly near 210 K.

Chou, F. C.; Johnston, D. C.

1996-07-01

314

Identification of new astatine isotopes using the gas-filled magnetic separator, Sassy  

SciTech Connect

A He-filled on-line separator system was built at the SuperHILAC and used to study the fusion products in the reaction /sup 56/Fe + /sup 141/Pr. The new neutron-deficient isotopes /sup 194/At and /sup 195/At were produced in this bombardment as three- and two-neutron-out products, respectively, and were identified by the ..cap alpha..-..cap alpha.. time-correlation technique. The measured ..cap alpha.. energies and half lives are 7.20 +/- 0.02 MeV and 180 +/- 80 msec for /sup 194/At, and 7.12 +/- 0.02 MeV and 200 +/- 100 msec for /sup 195/At.

Yashita, S.

1983-01-01

315

Identification of new astatine isotopes using the gas-filled magnetic separator, SASSY  

SciTech Connect

A He-filled on-line mass separator system was built at the SuperHILAC and used to study the fusion products in the reaction /sup 56/Fe + /sup 141/Pr. The new neutron-deficient isotopes /sup 194/At and /sup 195/At were produced in this bombardment as three- and two- neutron-out products, respectively, and were identified by the ..cap alpha..-..cap alpha.. time-correlation technique. The measured ..cap alpha.. energies and half lives are 7.20 +- 0.02 MeV and 180 +- 80 msec for /sup 194/At, and 7.12 +- 0.02 MeV and 200 +- 100 msec for /sup 195/At. 66 references.

Yashita, S.

1984-02-01

316

Airborne surveys in the Arctic and Antarctic for geophysics, sea-ice thickness, and CryoSat validation  

NASA Astrophysics Data System (ADS)

Airborne laser and radar measurements over the Greenland ice sheet, Svalbard, and adjacent parts of the Arctic Ocean have been carried out by DTU-Space in a number of recent Danish/Greenlandic and European project campaigns, with the purpose to monitor ice sheet and sea-ice changes, support of Greenland societal needs (oil exploration and hydropower), and support of CryoSat pre-launch calibration and validation campaigns. The Arctic campaigns have been done using a Twin-Otter aircraft, carrying laser scanners and various radars. Since 2009 a new program of long-range gravity and magnetic surveys have been initiated using a Basler DC3 aircraft for large-scale surveys in the Arctic Ocean and Antarctica, with the 2010 cooperative Danish-Argentinean-Chilean-US ICEGRAV survey of the Antarctic Peninsula additionally including a UTIG 60 MHz ice-penetrating radar. In the paper we outline the recent and upcoming airborne survey activities, outline the usefulness of the airborne data for satellite validation (CryoSat and GOCE), and give examples of measurements and comparisons to satellite and in-situ data.

Forsberg, R.; Olesen, A. V.; Hvidegaard, S.; Skourup, H.

2010-12-01

317

The effect of charge separation on nonlinear electrostatic waves in a magnetized dusty plasma with two-temperature ions  

SciTech Connect

In view of the observations of parallel (to Earth's magnetic field) spiky electric field structures by the FAST satellite, a theoretical study is conducted using a dusty plasma model comprising Boltzmann distributed hot and cool ions, Boltzmann electrons and a negatively charged cold dust fluid to investigate the existence of similar low frequency nonlinear electrostatic waves in a dusty plasma which could have a similar appearance as the observed waveforms. Charge separation effects are incorporated into our model by the inclusion of Poisson's equation as opposed to assuming quasineutrality. The system of nonlinear equations is then numerically solved. The resulting electric field structure is examined as a function of various plasma parameters such as Mach number, driving electric field amplitude, bulk dust drift speed, particle densities and particle temperatures.

Maharaj, S. K. [Hermanus Magnetic Observatory, P.O. Box 32, Hermanus 7200 (South Africa); Bharuthram, R. [University of the Western Cape, Modderdam Road, Bellville 7530 (South Africa); Pillay, S. R. [University of KwaZulu-Natal, Private Bag X54001, Durban 4000 (South Africa); Singh, S. V.; Reddy, R. V.; Lakhina, G. S. [Indian Institute of Geomagnetism, New Panvel, Navi Mumbai-410218 (India)

2008-09-07

318

Pressure induced magnetic phase separation in La0.75Ca0.25MnO3 manganite.  

PubMed

The pressure dependence of the Curie temperature T(C)(P) in La(0.75)Ca(0.25)MnO(3) was determined by neutron diffraction up to 8 GPa, and compared with the metallization temperature T(IM)(P) (Postorino et al 2003 Phys. Rev. Lett. 91 175501). The behavior of the two temperatures appears similar over the whole pressure range, suggesting a key role of magnetic double-exchange also in the pressure regime where the superexchange interaction is dominant. The coexistence of antiferromagnetic and ferromagnetic peaks at high pressure and low temperature indicates a phase separated regime which is well reproduced with a dynamical mean-field calculation for a simplified model. A new P-T phase diagram has been proposed on the basis of the whole set of experimental data. PMID:22214651

Baldini, M; Capogna, L; Capone, M; Arcangeletti, E; Petrillo, C; Goncharenko, I; Postorino, P

2012-01-03

319

Initial assessment of CryoSat-2 Performance.  

NASA Astrophysics Data System (ADS)

Following the launch of CryoSat-2 in April 2010, we have examined the performance of the CryoSat-2 SAR Interferometer over the continental ice sheets of Antarctica and Greenland, the Artic Ocean, and, for the purposes of calibration, over the oceans. Our aim has been to provide confirmation of the engineering performance of the radar interferometer, and to provide an initial geophysical validation of the resulting elevation measurements. We have confirmed the engineering performance at system level of the interferometer through performing a sequence of satellite rolls over the oceans, which provide a surface of known behavior and surface gradient. The activity has identified some errors in the SARIN L1b data products presently issued by ESA. Once corrected, the ocean calibration has demonstrated that the interferometer measures across-track surface slopes with a precision of 25 micro-radians and an accuracy of 10 micro-radians, which may be compared with a pre-launch estimation of 100 micro-radians; in short, the engineering performance greatly its the specification. The elevation measurement over the ice sheets combines the interferometer measurement of across track slope with the range measurement deduced from the SAR echoes. We have examined the performance of the range estimation, and determined the range precision to be 19 cm RMS at 20 Hz. We have examined the retrieval of the phase information over the ice sheets, and found the phase estimates to be robust and little affected by the uncertain ice sheet topography. Based on the calibration of the interferometer, the contribution of the across track slope error is, at 0.4 mm, negligible. While the quantity of data available to us that contains the corrections identified by the interferometer is limited, we have been able to confirm the range precision values from a limited cross-over analysis. Over marine sea ice, we have verified the discrimination of sea ice and ocean lead returns using contemporaneous SAR imagery from ENVISAT. Using one month's of data, we have determined an initial dynamic topography that agrees with a high resolution region ocean model to 4 cm. We have estimated the precision of individual (20 Hz) measurements to be 2 cm. We have combined estimated the Arctic ice thickness for January and February 2011, and made a preliminary comparison with contemporaneous in-situ and air-borne estimates of thickness which agree to 20 cm. In summary, with the corrected data products, we are able to confirm that the system performance of CryoSat-2 will meet or exceed its specification over the continental and marine ice sheets.

Wingham, D.; Galin, N.; Ridout, A.; Cullen, R.; Giles, K. A.; Laxon, S. W.

2011-12-01

320

Separation of Intra- and Extramyocellular Lipid Signals in Proton MR Spectra by Determination of Their Magnetic Field Distribution  

NASA Astrophysics Data System (ADS)

In skeletal musculature intramyocellular (IMCL) and extramyocellular lipids (EMCL) are stored in compartments of different geometry and experience different magnetic field strengths due to geometrical susceptibility effects. The effect is strong enough to-at least partly-separate IMCL and EMCL contributions in 1H MR spectroscopy, despite IMCL and EMCL consisting of the same substances. The assessment of intramyocellular lipid stores in skeletal musculature by 1H MR spectroscopy plays an important role for studying physiological and pathological aspects of lipid metabolism. Therefore, a method using mathematical tools of Fourier analysis is developed to obtain the magnetic field distribution (MFD) from the measured spectra by deconvolution. A reference lipid spectrum is required which was recorded in tibial yellow bone marrow. It is shown that the separation of IMCL contributions can be performed more precisely-compared to other methods-based on the MFD. Examples of deconvolution in model systems elucidate the principle. Applications of the proposed approach on in vivo examinations in m. soleus and m. tibialis anterior are presented. Fitting the IMCL part of the MFD by a Gaussian lineshape with a linewidth kept fixed with respect to the linewidth of creatine and with the assumption of a smooth but not necessarily symmetrical shape for the EMCL part, the only free fit parameter, the amplitude of the IMCL part, is definite and subtraction leads to the EMCL part in the MFD. This procedure is especially justified for the soleus muscle showing a severely asymmetrical distribution which might lead to a marked overestimation of IMCL using common line fitting procedures. .

Steidle, G.; Machann, J.; Claussen, C. D.; Schick, F.

2002-02-01

321

A rapid method for detection of genetically modified organisms based on magnetic separation and surface-enhanced Raman scattering.  

PubMed

In this study, a new method combining magnetic separation (MS) and surface-enhanced Raman scattering (SERS) was developed to detect genetically modified organisms (GMOs). An oligonucleotide probe which is specific for 35 S DNA target was immobilized onto gold coated magnetic nanospheres to form oligonucleotide-coated nanoparticles. A self assembled monolayer was formed on gold nanorods using 5,5'-dithiobis (2-nitrobenzoic acid) (DTNB) and the second probe of the 35 S DNA target was immobilized on the activated nanorod surfaces. Probes on the nanoparticles were hybridized with the target oligonucleotide. Optimization parameters for hybridization were investigated by high performance liquid chromatography. Optimum hybridization parameters were determined as: 4 ?M probe concentration, 20 min immobilization time, 30 min hybridization time, 55 °C hybridization temperature, 750 mM buffer salt concentration and pH: 7.4. Quantification of the target concentration was performed via SERS spectra of DTNB on the nanorods. The correlation between the target concentration and the SERS signal was found to be linear within the range of 25-100 nM. The analyses were performed with only one hybridization step in 40 min. Real sample analysis was conducted using Bt-176 maize sample. The results showed that the developed MS-SERS assay is capable of detecting GMOs in a rapid and selective manner. PMID:22049365

Guven, Burcu; Boyac?, ?smail Hakk?; Tamer, Ugur; Çal?k, P?nar

2011-11-03

322

An investigation of artificial biasing in detrital zircon U-Pb geochronology due to magnetic separation in sample preparation  

NASA Astrophysics Data System (ADS)

The application of detrital zircon geochronology for provenance analysis is complicated by the presence of biases induced by natural processes and sample preparation. The biasing of age distributions as a result of magnetic susceptibility is illustrated using sensitive high resolution ion microprobe dating of detrital zircon from a metaquartzite sample partitioned using a Frantz magnetic barrier separator. The relationship of paramagnetism with U content, ?-dose, and discordance is demonstrated, but no relationship between grain size and discordance or age is found. The data also demonstrate that previous limits of zircon survival in sedimentary processes based on U content alone are too simplistic. Two age modes at ˜3150 and ˜2960 Ma are present in all the paramagnetic fractions; there is a bias toward the ˜3150 Ma mode being more prominent in the least-paramagnetic fractions. While the ˜2960 Ma is present in the least-paramagnetic fraction, it is argued that such fortuitous representation cannot be assumed before analysis. Such "there or not" provenance interpretations are considered simplistic, and at the very least there is no harm in broadening the range of paramagnetic fractions sampled for analysis. The results indicate a compromise between broad representation and analytical efficiency (avoiding discordant and thus unreliable results) can be made with a Frantz setting of ˜1.8 A and 10° side-slope.

Sircombe, Keith N.; Stern, Richard A.

2002-07-01

323

Signature of magnetic phase separation in the ground state of Pr1-xCaxMnO3  

SciTech Connect

Neutron scattering has been used to investigate the evolution of the long- and short-range charge-ordered (CO), ferromagnetic (FM), and antiferromagnetic (AF) correlations in single crystals of $\\rm Pr_{1-x}Ca_{x}MnO_3$ ($x$ = 0.3, 0.35 and 0.4). These correlations are a ssociated with the existence of spin clusters with populations that drastically depend on the doping ($x$) and temperature. Concentrated spin clusters coexist with long-range canted AF order in a wide temperature range for $x$ = 0.3 while clusters do not appear in the $x$ = 0.4 crystal. In contrast, both CO and AF order parameters in the $x$ = 0.35 crystal show a precipitous decrease below $\\sim$ 35 K where spin clusters form. These results provide direct evidence of magnetic phase separation and indicate that there is a critical doping $x_{c}$ (close to $x$ = 0.35) that divides the phase-separated site-centered from the homogeneous bond-centered or charge-disproportionated CO ground state.

Sha, Hao [Florida International University, Miami; Ye, Feng [ORNL; Dai, Pengcheng [ORNL; Fernandez-Baca, Jaime A [ORNL; Mesa, Dalgis [ORNL; Lynn, J. W. [National Institute of Standards and Technology (NIST); Tomioka, Y. [Correlated Electron Research Center (CERC), Japan; Tokura, Y. [University of Tokyo, Tokyo, Japan; Zhang, Jiandi [Florida International University, Miami

2008-01-01

324

High Resolution CryoFESEM of Microbial Surfaces  

NASA Astrophysics Data System (ADS)

The outer surfaces of three microorganisms, Giardia lamblia, Enterococcus faecalis, and Proteus mirabilis, were investigated by cryo-immobilization followed by sublimation of extracellular ice and cryocoating with either Pt alone or Pt plus carbon. Cryocoated samples were examined at [minus sign]125°C in either an in-lens field emission SEM or a below-the-lens field emission SEM. Cryocoating with Pt alone was sufficient for low magnification observation, but attempts to do high-resolution imaging resulted in radiolysis and cracking of the specimen surface. Double coating with Pt and carbon, in combination with high resolution backscatter electron detectors, enabled high-resolution imaging of the glycocalyx of bacteria, revealing a sponge-like network over the surface. High resolution examination of bacterial flagella also revealed a periodic substructure. Common artifacts included radiolysis leading to “cracking” of the surface, and insufficient deposition of Pt resulting in the absence of detectable surface topography.

Erlandsen, Stanley; Lei, Ming; Martin-Lacave, Ines; Dunny, Gary; Wells, Carol

2003-08-01

325

Assessing the benefits of focal pair cryo-electron tomography.  

PubMed

Cryo electron tomography provides nanometer-scale information on biological matter preserved in a close-to native state. The resolution of tomograms and structures resolved by sub-tomogram averaging is typically limited by the contrast transfer function of the electron microscope, which is especially critical for thick samples. Here, we report a method to increase the attainable resolution by recording tomographic 'focal pairs', which are pairs of tilt series of the same object acquired in complementary defocus conditions. Low defocus imaging provides high resolution at low contrast, while high defocus imaging yields high contrast at the price of limited resolution. Quantitative assessment of the quality of lipid bilayer reconstructions in the resulting tomograms demonstrates stable resolution preservation beyond 3 nm for cells thicker than 500 nm. Further, in computational simulations on synthetic datasets we show the applicability of the method to sub-tomogram averaging, demonstrating its potential for achieving higher resolution. PMID:22056466

Kudryashev, Mikhail; Stahlberg, Henning; Castaño-Díez, Daniel

2011-10-25

326

Removal of subsurface fluorescence in cryo-imaging using deconvolution.  

PubMed

We compared image restoration methods [Richardson-Lucy (RL), Wiener, and Next-image] with measured "scatter" point-spread-functions, for removing subsurface fluorescence from section-and-image cryo-image volumes. All methods removed haze, delineated single cells from clusters, and improved visualization, but RL best represented structures. Contrast-to-noise and contrast-to-background improvement from RL and Wiener were comparable and 35% better than Next-image. Concerning detection of labeled cells, ROC analyses showed RL ?Wiener > Next-image > no processing. Next-image was faster than other methods and less prone to image processing artifacts. RL is recommended for the best restoration of the shape and size of fluorescent structures. PMID:20941133

Krishnamurthi, Ganapathy; Wang, Charlie Y; Steyer, Grant; Wilson, David L

2010-10-11

327

Evidence for Two Separate But Interlaced Components of the Chromospheric Magnetic Field  

NASA Astrophysics Data System (ADS)

Chromospheric fibrils are generally thought to trace out horizontal magnetic fields that fan out from flux concentrations in the photosphere. A high-resolution (0.2") image taken in the core of the Ca II 854.2 nm line shows the dark fibrils within an active region remnant as fine, looplike features that are aligned parallel to each other and have lengths on the order of a supergranular diameter ( 30 Mm). Comparison with a line-of-sight magnetogram confirms that the fibrils are centered above intranetwork areas, with one end rooted just inside the neighboring plage or strong unipolar network but the other endpoint less clearly defined. Focusing on a particular arcade-like structure lying entirely on one side of a filament channel (large-scale polarity inversion), we find that the total amount of positive-polarity flux underlying this ``fibril arcade'' is 50 times greater than the total amount of negative-polarity flux. Thus, if the fibrils represent closed loops, they must consist of very weak fields (in terms of flux density), which are interpenetrated by a more vertical field that contains most of the flux. This surprising result suggests that the fibrils in unipolar regions connect the network to the nearby intranetwork flux, while the bulk of the network flux is diverted upward into the corona and connects to remote regions of the opposite polarity. We conclude that the chromospheric field near the edge of the network has an interlaced structure resembling that in sunspot penumbrae, with the fibrils representing the low-lying horizontal flux that remains trapped within the highly nonpotential chromospheric layer.

Muglach, Karin; Reardon, K.; Wang, Y.; Warren, H.

2012-05-01

328

Label-free visualization of ultrastructural features of artificial synapses via cryo-EM.  

PubMed

The ultrastructural details of presynapses formed between artificial substrates of submicrometer silica beads and hippocampal neurons are visualized via cryo-electron microscopy (cryo-EM). The silica beads are derivatized by poly-d-lysine or lipid bilayers. Molecular features known to exist at presynapses are clearly present at these artificial synapses, as visualized by cryo-EM. Key synaptic features such as the membrane contact area at synaptic junctions, the presynaptic bouton containing presynaptic vesicles, as well as microtubular structures can be identified. This is the first report of the direct, label-free observation of ultrastructural details of artificial synapses. PMID:22860164

Gopalakrishnan, Gopakumar; Yam, Patricia T; Madwar, Carolin; Bostina, Mihnea; Rouiller, Isabelle; Colman, David R; Lennox, R Bruce

2011-10-04

329

Nitride Fuel Development Using Cryo-process Technique  

SciTech Connect

A new cryo-process technique has been developed for the fabrication of advanced fuel for nuclear systems. The process uses a new cryo-processing technique whereby small, porous microspheres (<2000 µm) are formed from sub-micron oxide powder. A simple aqueous particle slurry of oxide powder is pumped through a microsphere generator consisting of a vibrating needle with controlled amplitude and frequency. As the water-based droplets are formed and pass through the microsphere generator they are frozen in a bath of liquid nitrogen and promptly vacuum freeze-dried to remove the water. The resulting porous microspheres consist of half micron sized oxide particles held together by electrostatic forces and mechanical interlocking of the particles. Oxide powder microspheres ranging from 750 µm to 2000 µm are then converted into a nitride form using a high temperature fluidized particle bed. Carbon black can be added to the oxide powder before microsphere formation to augment the carbothermic reaction during conversion to a nitride. Also, the addition of ethyl alcohol to the aqueous slurry reduces the surface tension energy of the droplets resulting in even smaller droplets forming in the microsphere generator. Initial results from this new process indicate a lower impurity contamination in the final nitrides due to the single feed stream of particles, material handling and conversion are greatly simplified, a minimum of waste and personnel exposure are anticipated, and finally the conversion kinetics may be greatly increased because of the small oxide powder size (sub-micron) forming the porous microsphere. Thus far the fabrication process has been successful in demonstrating all of these improvements with surrogate ZrO2 powder. Further tests will be conducted in the future using the technique on UO2 powders.

O'Brien, Brandi M; Windes, William E

2007-06-01

330

Tandem assays of protein and glucose with functionalized core/shell particles based on magnetic separation and surface-enhanced Raman scattering.  

PubMed

Tandem assays of protein and glucose in combination with mannose-functionalized Fe3 O4 @SiO2 and Ag@SiO2 tag particles have promising potential in effective magnetic separation and highly sensitive and selective SERS assays of biomaterials. It is for the first time that tandem assay of glucose is developed using SERS based on the Con A-sandwiched microstructures between the functionalized magnetic and tag particles. PMID:23585333

Kong, Xianming; Yu, Qian; Lv, Zhongpeng; Du, Xuezhong

2013-04-15

331

Chemically Driven Nanoscopic Magnetic Phase Separation at the SrTiO(3)(001)/La(1-x)Sr(x)CoO(3) Interface  

SciTech Connect

The degradation in magnetic properties in very thin film complex oxides is studied using SrTiO(3)(001)/La(1-x)Sr(x)CoO(3), providing unequivocal evidence for nanoscopic interfacial magnetic phase separation. Electron microscopy and spectroscopy reveal that this occurs due to inhomogeneity in local hole doping, driven by subtle, depthwise variations in the Sr and O stoichiometry. Simple thermodynamic and structural arguments for the origin of these variations are provided.

Torija, Maria [University of Minnesota; Sharma, M [University of Minnesota; Gazquez Alabart, Jaume [ORNL; Varela del Arco, Maria [ORNL; He, C. [University of Minnesota; Schmitt, J. [University of Minnesota; Borchers, J.A. [National Institute of Standards and Technology (NIST); Laver, M. [National Institute of Standards and Technology (NIST); El-Khatib, S. [University of Minnesota; Leighton, chris [University of Minnesota

2011-01-01

332

Magnetic anisotropy of phase-separated CaO–Fe 3O 4–SiO 2 glasses prepared from a two-liquids immiscible melt  

Microsoft Academic Search

The phase-separated glass containing magnetite in CaO–Fe3O4–SiO2 system was prepared through liquid–liquid stable immiscibility. Possibilities of the distortion of the phase-separation texture by elongation during quenching were investigated in order to introduce magnetic anisotropy in the glass. The sintered rods of raw materials were melted at 2200 °C first for homogenizing the liquid melt, and subsequently melted at 1800 °C

Atsuo Yasumori; Akio Koike; Yoshikazu Kameshima; Kiyoshi Okada; Hiroaki Nishio

2002-01-01

333

Effect of Intentional Cryo-Injury to the Renal Collecting System  

Microsoft Academic Search

PurposeWe determined the short-term and long-term sequelae of intentional cryoablation of the renal pelvicaliceal system and evaluated whether continuous irrigation of the renal pelvicaliceal system with warm saline protects it against cryo-injury.

GYUNG TAK SUNG; INDERBIR S. GILL; THOMAS H. S. HSU; ANOOP M. MERANEY; MAREK SKACEL; JENIFER A. BRAINARD; ERICK M. REMER

2003-01-01

334

Movies of ice-embedded particles enhance resolution in electron cryo-microscopy  

PubMed Central

Summary Low-dose images obtained by electron cryo-microscopy (cryo-EM) are often affected by blurring caused by sample motion during electron beam exposure, degrading signal especially at high resolution. We show here that we can align frames of movies, recorded with a direct electron detector during beam exposure of rotavirus double-layered particles, thereby greatly reducing image blurring caused by beam-induced motion and sample stage instabilities. This procedure increases the efficiency of cryo-EM imaging and enhances the resolution obtained in three-dimensional reconstructions of the particle. Employing movies in this way is generally applicable to all cryo-EM samples and should also improve the performance of mid-range electron microscopes that may have limited mechanical stability and beam coherence.

Campbell, Melody G.; Cheng, Anchi; Brilot, Axel F.; Moeller, Arne; Lyumkis, Dmitry; Veesler, David; Pan, Junhua; Harrison, Stephen C.; Potter, Clinton S.; Carragher, Bridget; Grigorieff, Nikolaus

2012-01-01

335

3.88 ? structure of cytoplasmic polyhedrosis virus by cryo-electron microscopy  

PubMed Central

Cytoplasmic polyhedrosis virus (CPV) is unique within the Reoviridae family in having a turreted single-layer capsid contained within polyhedrin inclusion bodies, yet being fully capable of cell entry and endogenous RNA transcription1–4. Biochemical data have shown that the amino-terminal 79 residues of the CPV turret protein (TP) is sufficient to bring CPV or engineered proteins into the polyhedrin matrix for micro-encapsulation5,6. Here we report the three-dimensional structure of CPV at 3.88Å resolution using single-particle cryo-electron microscopy. Our map clearly shows the turns and deep grooves of ?-helices, the strand separation in ?-sheets, and densities for loops and many bulky side chains; thus permitting atomic model-building effort from cryoelectron microscopy maps. We observed a helix-to-?-hairpin conformational change between the two conformational states of the capsid shell protein in the region directly interacting with genomic RNA. We have also discovered a messenger RNA release hole coupled with the mRNA capping machinery unique to CPV. Furthermore, we have identified the polyhedrin-binding domain, a structure that has potential in nanobiotechnology applications.

Yu, Xuekui; Jin, Lei; Zhou, Z. Hong

2009-01-01

336

Zernike Phase Contrast Cryo-Electron Microscopy and Tomography for Structure Determination at Nanometer and Sub-Nanometer Resolutions  

PubMed Central

SUMMARY Zernike phase contrast cryo-electron microscopy (ZPC-cryoEM) is an emerging technique which is capable of producing higher image contrast than conventional cryoEM. By combining this technique with advanced image processing methods, we achieved subnanometer resolution for two biological specimens: 2-D bacteriorhodopsin crystal and epsilon15 bacteriophage. For an asymmetric reconstruction of epsilon15 bacteriophage, ZPC-cryoEM can reduce the required amount of data by a factor of ~3 compared to conventional cryoEM. The reconstruction was carried out to 13 Å resolution without the need to correct the contrast transfer function. New structural features at the portal vertex of the epsilon15 bacteriophage are revealed in this reconstruction. Using ZPC cryo-electron tomography (ZPC-cryoET), a similar level of data reduction and higher resolution structures of epsilon15 bacteriophage can be obtained relative to conventional cryoET. These results show quantitatively the benefits of ZPC-cryoEM and -cryoET for structural determinations of macromolecular machines at nanometer and subnanometer resolutions.

Murata, Kazuyoshi; Liu, Xiangan; Danev, Radostin; Jakana, Joanita; Schmid, Michael F.; King, Jonathan; Nagayama, Kuniaki; Chiu, Wah

2010-01-01

337

CHOYCE: a web server for constrained homology modelling with cryoEM maps  

PubMed Central

Summary: CHOYCE is a web server for homology modelling of protein components and the fitting of those components into cryo electron microscopy (cryoEM) maps of their assemblies. It provides an interactive approach to improving the selection of models based on the quality of their fit into the EM map. Availability: http://choyce.ismb.lon.ac.uk/ Contact: m.topf@cryst.bbk.ac.uk; reda.rawi@uni-due.de Supplementary information: Supplementary data are available at Bioinformatics online.

Rawi, Reda; Whitmore, Lee; Topf, Maya

2010-01-01

338

The making of frozen-hydrated, vitreous lamellas from cells for cryo-electron microscopy  

Microsoft Academic Search

There has been a long standing desire to produce thick (up to 500nm) cryo-sections of fully hydrated cells and tissue for high-resolution analysis in their natural state by cryo-transmission electron microscopy. Here, we present a method that can successfully produce sections (lamellas in FIB-SEM terminology) of fully hydrated, unstained cells from high-pressure frozen samples by focused ion beam (FIB) milling.

Michael F. Hayles; D. A. Matthijs de Winter; Chris T. W. M. Schneijdenberg; Johannes D. Meeldijk; Uwe Luecken; Hans Persoon; Jeroen de Water; Frank de Jong; Bruno M. Humbel; Arie J. Verkleij

2010-01-01

339

Near-atomic resolution reconstructions of icosahedral viruses from electron cryo-microscopy  

PubMed Central

Nine different near-atomic resolution structures of icosahedral viruses, determined by electron cryo-microscopy and published between early 2008 and late 2010, fulfill predictions made 15 years ago that single-particle cryo-EM techniques could visualize molecular detail at 3 – 4 Å resolution. This review summarizes technical developments, both in instrumentation and in computation, that have led to the new structures, which advance our understanding of virus assembly and cell entry.

Grigorieff, Nikolaus; Harrison, Stephen C.

2011-01-01

340

Imaging system for creating 3D block-face cryo-images of whole mice  

Microsoft Academic Search

We developed a cryomicrotome\\/imaging system that provides high resolution, high sensitivity block-face images of whole mice or excised organs, and applied it to a variety of biological applications. With this cryo-imaging system, we sectioned cryo-preserved tissues at 2-40 mum thickness and acquired high resolution brightfield and fluorescence images with microscopic in-plane resolution (as good as 1.2 mum). Brightfield images of

Debashish Roy; Michael Breen; Olivier Salvado; Meredith Heinzel; Eliot McKinley; David Wilson

2006-01-01

341

Enhanced volume rendering techniques for high-resolution color cryo-imaging data  

Microsoft Academic Search

We are developing enhanced volume rendering techniques for color image data. One target application is cryo-imaging, which provides whole-mouse, micron-scale, anatomical color, and molecular fluorescence image volumes by alternatively sectioning and imaging the frozen tissue block face. With the rich color images provided by cryo-imaging, we use true-color volume rendering and visually enhance anatomical regions by proper selection of voxel

Madhusudhana Gargesha; Mohammed Qutaish; Debashish Roy; Grant Steyer; Hauke Bartsch; David L. Wilson

2009-01-01

342

Effect of cryo-rolling on age hardening of Cu–1.5Ti alloy  

Microsoft Academic Search

Cryo-rolling, i.e. deformation at liquid nitrogen temperature (LNT) has been attempted on several metals to obtain very fine grain sizes and improved strength levels. In the present study, the influence of cryo-rolling with deformation up to 90% on age hardening behaviour of Cu–1.5Ti alloy has been investigated using hardness and tensile tests and optical as well as transmission electron microscopy

S. Nagarjuna; U. Chinta Babu; Partha Ghosal

2008-01-01

343

Retracking CryoSat-2 Ocean Waveforms for Optimal Gravity Field Recovery  

NASA Astrophysics Data System (ADS)

Achieving improved accuracy of the global marine gravity field derived from satellite altimetry depends primarily on two factors - a dense spatial distribution of ground tracks and high range measurement precision. CryoSat-2 is the first altimeter in the past 15 years that offers advancements in both of these capabilities. Over the ocean, the altimeter is operated in two modes, which produce distinct returned signals - one is similar to the conventional pulse-limited waveform, while the new SAR waveform results from along-track focusing. In order to extract physical measurements of the ocean surface, we are developing the models and algorithms for estimating the arrival time of the leading edge of both waveform types, specifically to enhance gravity field recovery. For the conventional-mode data, we have modified our two-pass approach originally developed for retracking ERS-1 waveforms and demonstrate a factor of 1.4 improvement in range precision for CryoSat-2. We attribute this to its 2 times higher pulse repetition frequency. Waveform retracking models and methods for the SAR mode data are still in active development by the community. We are testing three approaches to SAR waveform retracking. The simplest SAR waveform model (Raney, 1998) assumes a boxcar beamform along the track for a perfectly flat ocean surface, which results in a functional form that has the return power rising as the square root of time. A complete analytic waveform model accounts for the effects of a rough surface. Therefore, the flat ocean surface response is convolved with a Gaussian wave height model. We have obtained a solution for the functional form for this first model as well as its derivatives with respect to the arrival time and rise time parameters. The second retracking approach assumes a Gaussian beamform along the track, and this leads to a modified Bessel function representation of the waveform. This particular analytic model for a flat ocean surface cannot be convolved exactly with a Gaussian wave height model, and thus we resort to using a series approximation and numerical integration in separate instances. The third approach utilizes a purely numerical integration via quadrature of both the flat ocean response and the Gaussian wave height model. Comparing the modeled power from these three approaches results in remarkably similar waveform shapes with less than 10% differences for the flat ocean case and smaller differences for a typical Gaussian wave height. The range precision of the SAR mode data is expected to be 2 times better than the conventional mode data. We will select the optimal retracking approach based on the analysis of the CryoSat-2 SAR waveforms, which involves evaluating the data through comparisons with EGM2008 as well as through the analysis of repeat tracks.

Garcia, E. S.; Sandwell, D. T.

2011-12-01

344

MAGNETIC DRUM SEPARATOR PERFORMANCE SCALPING SHREDDED TROMMEL OVERFLOW AT NOMINAL DESIGN CONDITIONS. TEST NO. 4.03, RECOVERY 1, NEW ORLEANS  

EPA Science Inventory

This report describes the first test of the shredded trommel overs magnetic drum separator at the New Orleans, Louisiana, resource recovery facility. Shredded trommel overs refers to waste which reports to the oversize discharge from the trommel and is subsequently shredded. For ...

345

A new method in mineral magnetism for the separation of weak antiferromagnetic signal from a strong ferrimagnetic background  

Microsoft Academic Search

This paper describes a new magnetic method for determining the contribution of weakly magnetic hematite against a strongly magnetic (e.g. magnetite) background. The method involves measurements of Mfr, a residual or ``final'' remanence after hysteretic demagnetization of saturated isothermal remanent magnetization. In terms of sensitivity and precision, our proposed method is superior to the currently popular approach known as the

Qingsong Liu; Subir K. Banerjee; Michael J. Jackson; Rixiang Zhu; Yongxin Pan

2002-01-01

346

Design of a core-shell type immuno-magnetic separation system and multiplex PCR for rapid detection of pathogens from food samples.  

PubMed

We report an immuno-magnetic separation system developed by the immobilization of pathogen-specific antibodies on the core-shell magnetic beads. The magnetic beads were grafted with glycidylmethacrylate (GMA) using surface-initiated atom transfer radical polymerization (SI-ATRP). For immuno-magnetic separation (IMS) of target bacterial cells from others, antibodies for Escherichia coli and Salmonella enterica serovar Typhimurium cells were immobilized on the magnetic beads via glutaraldehyde coupling reaction. Our IMS system successfully separated Salmonella cells when the concentrations of target (i.e., Salmonella) and interfering (i.e., E. coli) cells were at the same level. Polymerase chain reaction (PCR) assays amplifying the rfb/rfbE region of the E. coli genome and a 647-bp fragment of the invA region of Salmonella were performed as the specific selection to accurately confirm the presence of E. coli and Salmonella, respectively. IMS and multiplex PCR methods can be used for specific and quantitative detection of pathogens from food samples. Thus, this study developed a reliable and direct system for rapid detection of Salmonella and E. coli in food samples. In addition, IMS method could be easily adapted to detect other pathogens by selecting the pertinent antibody. PMID:24048640

Ozalp, V Cengiz; Bayramoglu, Gulay; Arica, M Yakup; Oktem, H Avni

2013-09-19

347

Selective separation and enrichment of glibenclamide in health foods using surface molecularly imprinted polymers prepared via dendritic grafting of magnetic nanoparticles.  

PubMed

In this paper, the novel surface molecularly imprinted polymers based on dendritic-grafting magnetic nanoparticles were developed to enrich and separate glibenclamide in health foods. The density functional theory method was used to give theoretical directions to the synthesis of molecularly imprinted polymers. The polymers were prepared by using magnetic nanoparticles as supporting materials, methacrylic acid as the functional monomer, and ethylene glycol dimethacrylate as the cross-linker. The characteristics of magnetic nanoparticles and polymers were measured by transmission electron microscope and SEM, respectively. The enriching ability of molecularly imprinted polymers was measured by Freundlich Isotherm. The molecularly imprinted polymers were used as dispersive SPE materials to enrich, separate, and detect glibenclamide in health foods by HPLC. The average recoveries of glibenclamide in spiked health foods were 81.46-93.53% with the RSD < 4.07%. PMID:23418142

Wang, Ruoyu; Wang, Yang; Xue, Cheng; Wen, Tingting; Wu, Jinhua; Hong, Junli; Zhou, Xuemin

2013-02-18

348

Multifunctional inorganic-organic hybrid nanospheres for rapid and selective luminescence detection of TNT in mixed nitroaromatics via magnetic separation.  

PubMed

Rapid, sensitive and selective detection of 2,4,6-trinitrotoluene (TNT) in aqueous solution differentiating from other nitroaromatics and independent of complicated instruments is in high demand for public safety and environmental monitoring. Despite of many methods for TNT detection, it is hard to differentiate TNT from 2,4,6-trinitrophenol (TNP) due to their highly similar structures and properties. In this work, via a simple and versatile method, LaF3?Ce(3+)-Tb(3+)and Fe3O4 nanoparticle-codoped multifunctional nanospheres were prepared through self-assembly of the building blocks. The luminescence of these nanocomposites was dramatically quenched via adding nitroaromatics into the aqueous solution. After the magnetic separation, however, the interference of other nitroaromatics including 2,4,6-trinitrophenol (TNP), 2,4-dinitrotoluene (DNT), and nitrobenzene (NB) was effectively overcome due to the removal of these coexisting nitroaromatics from the surface of nanocomposites. Due to the formation of TNT(-)-RCONH3(+), the TNT was attached to the surface of the nanocomposites and was quantitatively detected by the postexposure luminescence quenching. Meanwhile, the luminescence intensity is negatively proportional to the concentration of TNT in the range of 0.01-5.0?g/mL with the 3? limit of detection (LOD) of 10.2ng/mL. Therefore, the as-developed method provides a novel strategy for rapid and selective detection of TNT in the mixture solution of nitroaromatics by postexposure luminescence quenching. PMID:24148441

Ma, Yingxin; Huang, Sheng; Wang, Leyu

2013-07-20

349

Improving the binding capacity of Ni2+ decorated porous magnetic silica spheres for histidine-rich protein separation.  

PubMed

Biomagnetic immobilization of histidine-rich proteins based on the single-step affinity adsorption of transition metal ions continues to be a suitable practice as a cost effective and a up scaled alternative to the to multiple-step chromatographic separations. In our previous work, we synthesised Porous Magnetic silica (PMS) spheres by one-step hydrothermal-assisted modified-stöber method. The obtained spheres were decorated with Ni(2+) and Co(2+), and evaluated for the capture of a H6-Tagged green fluorescence protein (GFP-H6) protein. The binding capacity of the obtained spheres was found to be slightly higher in the case Ni(2+) decorated PMS spheres (PMSNi). However, comparing with commercial products, the binding capacity was found to be lower than the expected. In this way, the present work is an attempt to improve the binding capacity of PMSNi to histidine-rich proteins. We find that increasing the amount of Ni(2+) onto the surface of the PMS spheres leads to an increment of the binding capacity to GFP-H6 by a factor of two. On the other hand, we explore how the size of histidine-rich protein can affect the binding capacity comparing the results of the GFP-6H to those of the His-tagged ?-galactosidase (?-GLA). Finally, we demonstrate that the optimization of the magnetophoresis parameters during washing and eluting steps can lead to an additional improvement of the binding capacity. PMID:23010043

Benelmekki, M; Caparros, C; Xuriguera, E; Lanceros-Mendez, S; Rodriguez-Carmona, E; Mendoza, R; Corchero, J L; Martinez, Ll M

2012-07-21

350

Preparation of anti-CD4 monoclonal antibody-conjugated magnetic poly(glycidyl methacrylate) particles and their application on CD4+ lymphocyte separation.  

PubMed

Novel immunomagnetic particles have been prepared for separation of CD4(+) lymphocytes. The magnetic nanoparticles with a diameter of approximately 5-6 nm were first synthesized by co-precipitation from ferrous and ferric iron solutions and subsequently encapsulated with poly(glycidyl methacrylate) (PGMA) by precipitation polymerization. Monoclonal antibody specific to CD4 molecules expressed on CD4(+) lymphocytes was conjugated to the surface of magnetic PGMA particles through covalent bonding between epoxide functional groups on the particle surface and primary amine groups of the antibodies. The generated immunomagnetic particles have successfully separated CD4(+) lymphocytes from whole blood with over 95% purity. The results indicated that these particles can be employed for cell separation and provide a strong potential to be applied in various biomedical applications including diagnosis, and monitoring of human diseases. PMID:21315903

Pimpha, Nuttaporn; Chaleawlert-umpon, Saowaluk; Chruewkamlow, Nuttapol; Kasinrerk, Watchara

2010-12-25

351

A novel magnetically separable gamma-Fe2O3/crosslinked chitosan adsorbent: preparation, characterization and adsorption application for removal of hazardous azo dye.  

PubMed

A novel magnetically separable adsorbent, namely magnetic gamma-Fe(2)O(3)/crosslinked chitosan composites (Mgamma-Fe(2)O(3)/CSCs), was prepared by microemulsion process and characterized by XRD, FT-IR, TGA, DSC, SEM and VSM. Adsorption of methyl orange (MO), used as a model pollutant, from aqueous solution on Mgamma-Fe(2)O(3)/CSCs was investigated. Characterization results indicated that magnetic gamma-Fe(2)O(3) nanoparticles have been introduced in Mgamma-Fe(2)O(3)/CSCs and kept intrinsic magnetic properties. The saturated magnetization (sigma(s)) of Mgamma-Fe(2)O(3)/CSCs can be expediently adjusted by changing additive dosage of gamma-Fe(2)O(3). Adsorption results showed that both nanocomposite adsorbents with weight ratio of gamma-Fe(2)O(3) to chitosan of 1:10 and 2:5 exhibited higher adsorption capacities and attained adsorption equilibria in shorter time compared with crosslinked chitosan. After adsorption, Mgamma-Fe(2)O(3)/CSCs were effectively separated from reaction solution in 10s by applying an adscititious magnetic field. Adsorption kinetics of MO on 1:10 Mgamma-Fe(2)O(3)/CSCs followed the pseudo-second-order kinetic model. Effects of both initial pH and adsorbent dosage on the adsorption of MO were remarkable in experimental conditions. PMID:20334972

Zhu, Hua-Yue; Jiang, Ru; Xiao, Ling; Li, Wei

2010-03-03

352

In-plane magnetic pattern separation in NiFe/NiO and Co/NiO exchange biased bilayers investigated by magnetic force microscopy  

NASA Astrophysics Data System (ADS)

Ion bombardment induced magnetic patterning (IBMP) was used to write in-plane magnetized micro and submicron patterns in exchange biased magnetic bilayers, where the magnetization directions of the adjacent patterns are antiparallel to each other in remanence. These magnetic patterns were investigated by non-contact magnetic force microscopy (MFM). It is shown that the recorded MFM images of the IBMP patterns in two exemplarily chosen standard layer systems (NiFe(4.8nm)/NiO(68nm) and Co(4.8nm)/NiO(68nm)) can be well described by a model within the point-dipole approximation for the tip magnetization. For 5 and 0.9?m wide bar patterns the domain wall widths between adjacent magnetically patterned areas were determined to a~1?m. The minimum magnetically stable pattern width was estimated to be 0.7?m in the standard system Co(4.8nm)/NiO(68nm).

Ehresmann, A.; Krug, I.; Kronenberger, A.; Ehlers, A.; Engel, D.

2004-09-01

353

Image formation modeling in cryo-electron microscopy.  

PubMed

Accurate modeling of image formation in cryo-electron microscopy is an important requirement for quantitative image interpretation and optimization of the data acquisition strategy. Here we present a forward model that accounts for the specimen's scattering properties, microscope optics, and detector response. The specimen interaction potential is calculated with the isolated atom superposition approximation (IASA) and extended with the influences of solvent's dielectric and ionic properties as well as the molecular electrostatic distribution. We account for an effective charge redistribution via the Poisson-Boltzmann approach and find that the IASA-based potential forms the dominant part of the interaction potential, as the contribution of the redistribution is less than 10%. The electron wave is propagated through the specimen by a multislice approach and the influence of the optics is included via the contrast transfer function. We incorporate the detective quantum efficiency of the camera due to the difference between signal and noise transfer characteristics, instead of using only the modulation transfer function. The full model was validated against experimental images of 20S proteasome, hemoglobin, and GroEL. The simulations adequately predict the effects of phase contrast, changes due to the integrated electron flux, thickness, inelastic scattering, detective quantum efficiency and acceleration voltage. We suggest that beam-induced specimen movements are relevant in the experiments whereas the influence of the solvent amorphousness can be neglected. All simulation parameters are based on physical principles and, when necessary, experimentally determined. PMID:23711417

Vulovi?, Miloš; Ravelli, Raimond B G; van Vliet, Lucas J; Koster, Abraham J; Lazi?, Ivan; Lücken, Uwe; Rullgård, Hans; Öktem, Ozan; Rieger, Bernd

2013-05-25

354

Development of external cooling cryo-resistive cable systems. Part 2: Insulation characteristics on 66 kV rated cryo-resistive testing cable  

NASA Astrophysics Data System (ADS)

Cryo-resistive cable system was tested to demonstrate dielectric characteristics. Dielectric characteristics of 66kV cryo-resistive cable at the start of immersion cooling in the liquid nitrogen were 2.25 specific dielectric constant and 0.18 percent dielectric loss which was less than 0.4 percent , the aimed value. Electrostatic capacity and dielectric loss tangent of dielectric characteristics under the applied voltage did not depend on the voltage and the dielectric loss was less than 0.4 percent through the temperature range from -170 to -190C. These values fulfilled the specifications on 275kV class cryo-resistive cable design. The tested cable passed the cable test on 66kV oil-filled cable (ac 90kV, 10 min), but broken down at ac 110kV on the way to endurance testing voltage 130kV. The breakdown occurred due to the mechanical damage of cable insulator by bending and thermal contraction of the cable. It is necessary from these facts to develop flexible cable terminal and joint which can absorb the contraction to realize 275kV cryo-resistive cable. (19 figs, 7 tabs, 15 refs).

Ishihara, Kaoru; Akita, Shige; Suzuki, Hiroshi; Ogata, Junichi; Nemoto, Minoru

1987-08-01

355

Consensus among flexible fitting approaches improves the interpretation of cryo-EM data  

PubMed Central

Cryo-elecron microscopy (Cryo-EM) can provide important structural information of large macromolecular assemblies in different conformational states. Recent years have seen an increase in structures deposited in the Protein Data Bank (PDB) by fitting a high-resolution structure into its low-resolution cryo-EM map. A commonly used protocol for accommodating the conformational changes between the X-ray structure and the cryo-EM map is rigid body fitting of individual domains. With the emergence of different flexible fitting approaches, there is a need to compare and revise these different protocols for the fitting. We have applied three diverse automated flexible fitting approaches on a protein dataset for which rigid domain fitting (RDF) models have been deposited in the PDB. In general, a consensus is observed in the conformations, which indicates a convergence from these theoretically different approaches to the most probable solution corresponding to the cryo-EM map. However, the result shows that the convergence might not be observed for proteins with complex conformational changes or with missing densities in cryo-EM map. In contrast, RDF structures deposited in the PDB can represent conformations that not only differ from the consensus obtained by flexible fitting but also from X-ray crystallography. Thus, this study emphasizes that a “consensus” achieved by the use of several automated flexible fitting approaches can provide a higher level of confidence in the modeled configurations. Following this protocol not only increases the confidence level of fitting, but also highlights protein regions with uncertain fitting. Hence, this protocol can lead to better interpretation of cryo-EM data.

Ahmed, Aqeel; Whitford, Paul C.; Sanbonmatsu, Karissa Y.; Tama, Florence

2011-01-01

356

Consensus among flexible fitting approaches improves the interpretation of cryo-EM data.  

PubMed

Cryo-elecron microscopy (cryo-EM) can provide important structural information of large macromolecular assemblies in different conformational states. Recent years have seen an increase in structures deposited in the Protein Data Bank (PDB) by fitting a high-resolution structure into its low-resolution cryo-EM map. A commonly used protocol for accommodating the conformational changes between the X-ray structure and the cryo-EM map is rigid body fitting of individual domains. With the emergence of different flexible fitting approaches, there is a need to compare and revise these different protocols for the fitting. We have applied three diverse automated flexible fitting approaches on a protein dataset for which rigid domain fitting (RDF) models have been deposited in the PDB. In general, a consensus is observed in the conformations, which indicates a convergence from these theoretically different approaches to the most probable solution corresponding to the cryo-EM map. However, the result shows that the convergence might not be observed for proteins with complex conformational changes or with missing densities in cryo-EM map. In contrast, RDF structures deposited in the PDB can represent conformations that not only differ from the consensus obtained by flexible fitting but also from X-ray crystallography. Thus, this study emphasizes that a "consensus" achieved by the use of several automated flexible fitting approaches can provide a higher level of confidence in the modeled configurations. Following this protocol not only increases the confidence level of fitting, but also highlights protein regions with uncertain fitting. Hence, this protocol can lead to better interpretation of cryo-EM data. PMID:22019767

Ahmed, Aqeel; Whitford, Paul C; Sanbonmatsu, Karissa Y; Tama, Florence

2011-10-13

357

Magnetically separable hybrid CdS-TiO2-Fe3O4 nanomaterial: Enhanced photocatalystic activity under UV and visible irradiation  

NASA Astrophysics Data System (ADS)

Magnetically separable photocatalyst of TiO2-CdS-Fe3O4@SiO2 nanocomposite was successfully prepared through a microwave heating method. The products exhibit enhanced photocatalystic activity which is more efficient than that of pure CdS and Degussa P25 TiO2 toward the degradation of RhB under both UV and visible irradiation. This is attributed to the charge separation and transformation from CdS to TiO2. The hysteresis loop of TiO2-CdS-Fe3O4@SiO2 nanocomposite indicates an excellent magnetic property with the saturated magnetization of 9 emu/g. We also show the fast magnetic separation behaviour of the TiO2-CdS-Fe3O4@SiO2 nanocomposite to remove and recycle the photocatalyst from the solution. These indicate TiO2-CdS-Fe3O4@SiO2 nanocomposite is an effective and convenient recyclable photocatalyst.

Bian, Xiaofang; Hong, Kunquan; Liu, Liqing; Xu, Mingxiang

2013-09-01

358

Nhs: Network-based Hierarchical Segmentation for Cryo-EM Density Maps  

PubMed Central

Electron cryo-microscopy (cryo-EM) experiments yield low-resolution (3–30Å) 3D-density maps of macromolecules. These density maps are segmented to identify structurally distinct proteins, protein domains, and sub-units. Such partitioning aids the inference of protein motions and guides fitting of high-resolution atomistic structures. Cryo-EM density map segmentation has traditionally required tedious and subjective manual partitioning or semi-supervised computational methods, while validation of resulting segmentations has remained an open problem in this field. Our network-based bias-free segmentation method for cryo-EM density map segmentation, Nhs (Network-based hierarchical segmentation), provides the user with a multi-scale partitioning, reflecting local and global clustering, while requiring no user input. This approach models each map as a graph, where map voxels constitute nodes and edges connect neighboring voxels. Nhs initiates Markov diffusion (or random walk) on the weighted graph. As Markov probabilities homogenize through diffusion, an intrinsic segmentation emerges. We validate the segmentations with ground-truth maps based on atomistic models. When implemented on density maps in the 2010 Cryo-EM Modeling Challenge, Nhs efficiently and objectively partitions macromolecules into structurally and functionally relevant sub-regions at multiple scales.

Burger, Virginia; Chennubhotla, Chakra

2012-01-01

359

Orientation dependence of the interfacial magnetic phase separation in epitaxial La1-xSrxCoO3 films on SrTiO3 and LaAlO3 substrates  

Microsoft Academic Search

We have observed interfacial magneto-electronic phase separation in epitaxial films of La1-xSrxCoO3 (x > 0.18) on SrTiO3 (001) substrates, where no such phase separation occurs in the bulk. This magnetic phase separation was detected indirectly via reduced magnetization, insulating transport, and the presence of intercluster type GMR, and subsequently verified directly by small-angle neutron scattering. Z contrast STEM\\/EELS results reveal

M. Sharma; M. A. Torija; J. Schmidt; C. He; C. Leighton; J. Gazquez; M. Varela; M. Laver; S. El-Khatib; B. B. Maranville; J. A. Borchers; M. Zhernenkov; M. R. Fitzsimmons

2010-01-01

360

Anomalous phase separation in La0.225Pr0.4Ca0.375MnO3: consequence of temperature and magnetic-field cycles  

NASA Astrophysics Data System (ADS)

The evolutions of electronic phase separation in manganites La0.225Pr0.4Ca0.375MnO3 are studied by the specific temperature and magnetic-field cycling experiments. It is found that the electronic phase separation state at low temperature can be tuned substantially by temperature and/or magnetic-field cycles. Surprisingly, the initial more ferromagnetic metallic (FMM) nuclei can impede the growth of these nuclei during the cooling process. It implies that there must coexist more than two phases which take part in the complex first-order phase transitions, and the charge-disordered insulating phase is possible, one of the parent phases transiting into the FMM phase at low temperature. In addition, the accommodation strain is suggested to control the nucleation and growth of FMM domains.

Yan, Z. B.; Liu, J.-M.

2011-07-01

361

CRYOGENIC SYSTEM FOR BEPCII SRF CAVITY, IR QUADRUPOLE AND DETECTOR SOLENOID MAGNETS.  

SciTech Connect

Beijing Electron-Positron Collider Upgrade (BEPCII) requires three types of superconducting facilities, including one pair of SRF cavities, one pair of interaction region quadrupole magnets, and one detector solenoid magnet. The cryo-plant for BEPCII has a total cooling capacity of 1kW at 4.5K, which is composed of two separate helium refrigerators of 500W each. Two refrigerators share the same gas storage and recovery system. The engineering design for the cryogenic systems, including power leads, control dewars, subcooler, cryogenic valve boxes, cryogenic transfer-lines and cryogenic controls, is completed. The production of its subsystem is under way. This paper summarizes the progress in cryogenics of the BEPCII project.

JIA,J.X.; WANG.L.

2004-05-11

362

Application of a Peptide-Mediated Magnetic Separation-Phage Assay for Detection of Viable Mycobacterium avium subsp. paratuberculosis to Bovine Bulk Tank Milk and Feces Samples?†  

PubMed Central

Naturally contaminated bovine bulk tank milk (n = 44) and feces (n = 39) were tested for the presence of viable Mycobacterium avium subsp. paratuberculosis by a novel peptide-mediated magnetic separation-phage (PMS-phage) assay. Counts of viable M. avium subsp. paratuberculosis cells ranging from 1 to 110 PFU/50 ml of milk and 6 to 41,111 PFU/g of feces were indicated by the PMS-phage assay.

Foddai, Antonio; Strain, Samuel; Whitlock, Robert H.; Elliott, Christopher T.; Grant, Irene R.

2011-01-01

363

Magnetism.  

National Technical Information Service (NTIS)

This program describes magnets and magnetic materials by pointing out the characteristics of the magnetic field, the molecular arrangement of magnetized and unmagnetized metals, the laws of attraction and repulsion, and the factors that affect the amount ...

1972-01-01

364

Analysis of the intact surface layer of Caulobacter crescentus by cryo-electron tomography.  

PubMed

The surface layers (S layers) of those bacteria and archaea that elaborate these crystalline structures have been studied for 40 years. However, most structural analysis has been based on electron microscopy of negatively stained S-layer fragments separated from cells, which can introduce staining artifacts and allow rearrangement of structures prone to self-assemble. We present a quantitative analysis of the structure and organization of the S layer on intact growing cells of the Gram-negative bacterium Caulobacter crescentus using cryo-electron tomography (CET) and statistical image processing. Instead of the expected long-range order, we observed different regions with hexagonally organized subunits exhibiting short-range order and a broad distribution of periodicities. Also, areas of stacked double layers were found, and these increased in extent when the S-layer protein (RsaA) expression level was elevated by addition of multiple rsaA copies. Finally, we combined high-resolution amino acid residue-specific Nanogold labeling and subtomogram averaging of CET volumes to improve our understanding of the correlation between the linear protein sequence and the structure at the 2-nm level of resolution that is presently available. The results support the view that the U-shaped RsaA monomer predicted from negative-stain tomography proceeds from the N terminus at one vertex, corresponding to the axis of 3-fold symmetry, to the C terminus at the opposite vertex, which forms the prominent 6-fold symmetry axis. Such information will help future efforts to analyze subunit interactions and guide selection of internal sites for display of heterologous protein segments. PMID:20833802

Amat, Fernando; Comolli, Luis R; Nomellini, John F; Moussavi, Farshid; Downing, Kenneth H; Smit, John; Horowitz, Mark

2010-09-10

365

An integrated passive micromixer-magnetic separation-capillary electrophoresis microdevice for rapid and multiplex pathogen detection at the single-cell level.  

PubMed

Here we report an integrated microdevice consisting of an efficient passive mixer, a magnetic separation chamber, and a capillary electrophoretic microchannel in which DNA barcode assay, target pathogen separation, and barcode DNA capillary electrophoretic analysis were performed sequentially within 30 min for multiplex pathogen detection at the single-cell level. The intestine-shaped serpentine 3D micromixer provides a high mixing rate to generate magnetic particle-pathogenic bacteria-DNA barcode labelled AuNP complexes quantitatively. After magnetic separation and purification of those complexes, the barcode DNA strands were released and analyzed by the microfluidic capillary electrophoresis within 5 min. The size of the barcode DNA strand was controlled depending on the target bacteria (Staphylococcus aureus, Escherichia coli O157:H7, and Salmonella typhimurium), and the different elution time of the barcode DNA peak in the electropherogram allows us to recognize the target pathogen with ease in the monoplex as well as in the multiplex analysis. In addition, the quantity of the DNA barcode strand (?10(4)) per AuNP is enough to be observed in the laser-induced confocal fluorescence detector, thereby making single-cell analysis possible. This novel integrated microdevice enables us to perform rapid, sensitive, and multiplex pathogen detection with sample-in-answer-out capability to be applied for biosafety testing, environmental screening, and clinical trials. PMID:21870015

Jung, Jae Hwan; Kim, Gha-Young; Seo, Tae Seok

2011-08-25

366

Magnetic properties of phase separated Fe3O4-TiO2-SiO2 glasses prepared from a two-liquids immiscible melt  

NASA Astrophysics Data System (ADS)

The glassy composite materials were prepared by quenching the phase separated melts in two-liquids immiscibility region of Fe3O4-TiO2-SiO2 ternary system. The fine phase-separation textures which consisted of Fe-Ti rich phase and Si rich one were formed in the samples, and the precipitation of Fe3O4-TiO2 solid solution was observed in the samples of the specific compositions. The samples containing Fe3O4-TiO2 solid solution showed ferrimagnetic properties on their magnetization curves. In low Fe3O4-TiO2 content, coercivity increased with increase of Fe3O4-TiO2 content since the precipitated particles in the samples grew and had single magnetic domain. In high Fe3O4-TiO2 content, the coercivity decreased with increase of Fe3O4-TiO2 content because the magnetostatical interparticle interaction among the precipitated particles appeared. These results indicate that the magnetic properties of the composite materials owing to the crystalline phase and its size can be controlled by utilizing the phase separation in this system.

Kono, K.; Kishi, T.; Ohgaki, T.; Yasumori, A.

2008-03-01

367

[A review of automatic particle recognition in Cryo-EM images].  

PubMed

Advances in cryo-electron microscopy (Cryo-EM) and single-particle reconstruction have led to increasingly high resolutions of macromolecular three-dimensional reconstruction. However, for keeping up the continuing improvements in resolution, it is necessary to increase the number of particles included in performing reconstructions. Manual selection of particles, even assisted by computer, is a bottleneck of single-particle reconstruction. Cryo-EM image has low signal-to-noise ratio and low contrast, which leads to difficulty in particle picking. Various approaches have been developed to address the problem of automatic particle. This paper describes the application of template-based method, edge based method, feature-based method, neural network, DoG-based and simulated annealing approach in particle picking. The characteristics of various approaches are discussed, and the future development is presented. PMID:21089695

Wu, Xiaorong; Wu, Xiaoming

2010-10-01

368

Visualization of macromolecular complexes using cryo-electron microscopy with FEI Tecnai transmission electron microscopes  

PubMed Central

This protocol details the steps used for visualizing the frozen-hydrated grids as prepared following the accompanying protocol entitled ‘Preparation of macromolecular complexes for visualization using cryo-electron microscopy.’ This protocol describes how to transfer the grid to the microscope using a standard cryo-transfer holder or, alternatively, using a cryo-cartridge loading system, and how to collect low-dose data using an FEI Tecnai transmission electron microscope. This protocol also summarizes and compares the various options that are available in data collection for three-dimensional (3D) single-particle reconstruction. These options include microscope settings, choice of detectors and data collection strategies both in situations where a 3D reference is available and in the absence of such a reference (random-conical and common lines).

Grassucci, Robert A; Taylor, Derek; Frank, Joachim

2009-01-01

369

Negative staining and Cryo-negative Staining of Macromolecules and Viruses for TEM  

PubMed Central

In this review we cover the technical background to negative staining of biomolecules and viruses, and then expand upon the different possibilities and limitations. Topics range from conventional air-dry negative staining of samples adsorbed to carbon support films, the variant termed the “negative staining-carbon film” technique and negative staining of samples spread across the holes of holey carbon support films, to a consideration of dynamic/time-dependent negative staining. For each of these approaches examples of attainable data are given. The cryo-negative staining technique for the specimen preparation of frozen-hydrated/vitrified samples is also presented. A detailed protocol to successfully achieve cryo-negative staining with ammonium molybdate is given, as well as examples of data, which support the claim that cryo-negative staining provides a useful approach for the high-resolution study of macromolecular and viral structure.

De Carlo, Sacha; Harris, J. Robin

2010-01-01

370

3D structural analysis of flagella/cilia by cryo-electron tomography.  

PubMed

Three dimensional arrangement of proteins inside the axoneme is essential information to elucidate the flagellar/ciliary bending mechanism. Cryo-electron tomography provides structural information in situ at ~30 Å resolution and thus is a suitable method for flagella/cilia research. The biggest challenge in cryo-electron tomography is the low signal-to-noise ratio. Therefore, subtomogram averaging, an in silico processing step to detect identical structural units based on 3D image analysis, aligns them three dimensionally and average is required to improve the signal-to-noise ratio. When structural units are not exactly identical, they must be classified. In this chapter, we describe our strategy to extract, align, classify, and average molecular structures from cryo-electron tomograms of flagella/cilia, utilizing longitudinal periodicity and pseudo-ninefold symmetry in the axoneme. PMID:23498747

Bui, Khanh Huy; Ishikawa, Takashi

2013-01-01

371

Simple synthesis of functionalized superparamagnetic magnetite/silica core/shell nanoparticles and their application as magnetically separable high-performance biocatalysts  

SciTech Connect

We report on the facile large-scale synthesis of magnetite@silica core-shell nanoparticles by a simple addition of tetraethyl orthosilicate (TEOS) into reverse micelles during the formation of uniformly-sized magnetite nanoparticles. The size of magnetic core was determined by the ratio of solvent and surfactant in reverse micelle solution while the thickness of silica shell could be easily controlled by adjusting the amount of added TEOS. Amino group functional groups were grafted to the magnetic nanoparticles, and crosslinked enzyme clusters (CEC) were fabricated on the surface of magnetite@silica nanoparticles. The resulting hybrid materials of magnetite and CEC were magnetically separable, highly active, and stable enough to show no decrease of enzyme activity under rigorous shaking for more than 15 days.

Lee, Jinwoo; Lee, Youjin; Youn, Jongkyu; Na, Hyon Bin; Yu, Taekyung; Kim, Hwan O.; Lee, Sang-mok; Koo, Yoon-mo; Kwak, Ja Hun; Park, Hyun-Gyu; Chang, Ho Nam; Hwang, Misun; Park, Je-Geun; Kim, Jungbae; Hyeon, Taeghwan

2008-01-01

372

Structure, Composition and Magnetic Properties of Ferrofluid Nanoparticles after Separation / Feromagn?tisko Š?idrumu Nanoda?i?u Strukt?ras, Sast?va un Magn?tisko ?paš?bu Izmai?as P?c Separ?cijas  

NASA Astrophysics Data System (ADS)

The structure, composition and magnetic properties of iron oxide nanoparticles are studied as dependent on the synthesis technology and method of separation in ferrofluids. The goal of the present study is to improve the magnetic properties of wet-synthesized nanoparticles and achieve a narrow nanoparticle size distribution. The results of measurements show that by varying the conditions of the chemical coprecipitation method, different compositions and structures of the nanoparticles could be obtained. The separation of ferrite nanoparticles of a polydisperse colloid by centrifugation as well as by HGMS provides the possibility to obtain a nanoparticle set with narrow size distribution Darb? izp?t?tas dzelzs oks?da nanoda?i?u strukt?ras, sast?va un magn?tisko ?paš?bu izmai?as atkar?b? no sint?zes tehnolo?ijas, k? ar? no daž?d?m feromagn?tisko š?idrumu separ?cijas metod?m. Magn?tisko nanoda?i?u strukt?ra, sast?vs un izm?rs tika p?t?ts ar rentgenstaru difraktometru un transmisijas elektronu mikroskopu. Da?i?u magn?tisk?s ?paš?bas tika m?r?tas ar vibr?cijas magnetometru. P?t?jum? par?d?ts, ka, mainot magn?tisko nanoda?i?u sint?zes apst?k?us, k? ar?, separ?jot feromagn?tisko š?idrumu ar daž?d?m metod?m, var izgatavot paraugus ar nepieciešamaj?m specifiskaj?m ?paš?b?m

Kronkalns, G.; Kodols, M.; Maiorov, M. M.

2013-08-01

373

Cryo-electron tomography: moving towards revealing the viral life cycle of Rice dwarf virus  

PubMed Central

It is well known that viruses utilize the host cellular systems for their infection and replication processes. However, the molecular mechanisms underlying these processes are poorly understood for most viruses. To understand these molecular mechanisms, it is essential to observe the viral and virus-related structures and analyse their molecular interactions within a cellular context. Cryo-electron microscopy and tomography offer the potential to observe macromolecular structures and to analyse their molecular interactions within the cell. Here, using cryo-electron microscopy and tomography, the structures of Rice dwarf virus are reported within fully hydrated insect vector cells grown on electron microscopy grids towards revealing the viral infection and replication mechanisms.

Miyazaki, Naoyuki; Akita, Fusamichi; Nakagawa, Atsushi; Murata, Kazuyoshi; Omura, Toshihiro; Iwasaki, Kenji

2013-01-01

374

Retrofit implementation of Zernike phase plate imaging for cryo-TEM  

PubMed Central

In-focus phase-plate imaging is particularly beneficial for cryo-TEM because it offers a substantial overall increase in image contrast, without an electron dose penalty, and it simplifies image interpretation. We show how phase-plate cryo-TEM can be implemented with an appropriate existing TEM, and provide a basic practical introduction to use of thin-film (carbon) phase plates. We point out potential pitfalls of phase-plate operation, and discuss solutions. We provide information on evaluating a particular TEM for its suitability.

Marko, Michael; Leith, ArDean; Hsieh, Chyongere; Danev, Radostin

2011-01-01

375

Wettability studies at the pore level: A new approach by use of Cryo-SEM  

SciTech Connect

Cryo-scanning electron microscopy (Cryo-SEM) is used to study the wettability of reservoir rocks from fluid distribution at irreducible water saturation, S{sub wi}, and residual oil saturation, S{sub or}. Results on mixed-wettability cores point out the importance of composition, distribution, and accessibility of minerals in determining the macroscopic behavior of the rocks. For the studied samples, wettability of sandstones is related to the presence of kaolinite, while wettability of carbonates seems to be related to pore-size distribution.

Robin, M.; Rosenberg, E. [Inst. Francais du Petrole, Rueil-Malmaison (France); Fassi-Fihri, O.

1995-03-01

376

Synthesis of Fe3O4@poly(methylmethacrylate-co-divinylbenzene) magnetic porous microspheres and their application in the separation of phenol from aqueous solutions.  

PubMed

A simple strategy to fabricate magnetic porous microspheres of Fe(3)O(4)@poly(methylmethacrylate-co-divinylbenzene) was demonstrated. The magnetic microspheres, consisting of polymer-coated iron oxide nanoparticles, were synthesized by the modified suspension polymerization of methacrylate and divinylbenzene in the presence of a magnetic fluid. The morphology and the properties of the magnetic porous microspheres were examined by scanning electron microscopy, transmission electron microscopy, superconducting quantum interference device, Fourier transform infrared spectroscopy, thermogravimetry, and X-ray powder diffraction. The pore size distribution and the specific surface area of the microspheres were measured by nitrogen sorption and mercury porosimetry technique. As predicted from the previous knowledge, the magnetic porous microspheres possessed a high specific surface area using n-hexane as a porogen. It was further found that the amounts of divinylbenzene and methacrylate, the ratio of porogens, and the dosage of ferrofluids affect the specific surface area of the microspheres. Furthermore, the microspheres were applied to remove phenol from aqueous solutions. The results showed that the microspheres had a high adsorption capacity for phenol and a high separation efficiency due to their porous structure, polar groups, and superparamagnetic characteristic. PMID:21601864

Tai, Yulei; Wang, Li; Gao, Jingmin; Amer, Wael A; Ding, Wenbing; Yu, Haojie

2011-05-04

377

Reaching the information limit in cryo-EM of biological macromolecules: experimental aspects.  

PubMed

Although cryo-electron microscopy (cryo-EM) of biological macromolecules has made important advances in the past few years, the level of current technical performance is still well below what the physics of electron scattering would allow. It should be possible, for example, to use cryo-EM to solve protein structures at atomic resolution for particle sizes well below 80 kDa, but currently this has been achieved only for particles at least 10 times larger than that. In this review, we first examine some of the reasons for this large gap in performance. We then give an overview of work that is currently in progress to 1), improve the signal/noise ratio for area detectors; 2), improve the signal transfer between the scattered electrons and the corresponding images; and 3), reduce the extent to which beam-induced movement causes a steep fall-off of signal at high resolution. In each case, there is substantial reason to think that cryo-EM can indeed be made to approach the estimated physical limits. PMID:21575566

Glaeser, Robert M; Hall, Richard J

2011-05-18

378

XYLEM FEEDING BY SPITTLEBUG NYMPHS: SOME OBSERVATIONS BY OPTICAL AND CRYO-SCANNING ELECTRON MICROSCOPY1  

Microsoft Academic Search

The feeding of spittlebug nymphs (Philaenus spumarius) from mature xylem vessels was studied by optical and cryo- analytical scanning electron microscopy. Feeding did not produce xylem embolisms and vessels remained liquid-filled during the day. Saliva secreted by the insect forms a hardened lining (salivary sheath) between the stylet bundle and the plant tissues. This sheath is continuous through the hole

LAURA J. CREWS; MARGARET E. MCCULLY; MARTIN J. CANNY; CHENG X. HUANG; LEWIS E. C. LING

379

3D cryo-section\\/imaging of blood vessel lesions for validation of MRI data  

Microsoft Academic Search

Vascular disease is a leading cause of death and disability in the western world. Diagnosis and staging of atherosclerosis is a challenge, especially with regards to the identification of plaque vulnerability. We are developing imaging methods based upon MRI and intravascular microcoils. In order to rigorously validate our MRI imaging methods and algorithms, we have developed a new cryo-imaging system

Olivier Salvado; Debashish Roy; Meredith Heinzel; Eliot McKinley; David Wilson

2006-01-01

380

Special features of phosphatidylcholine vesicles as seen in cryo-transmission electron microscopy  

Microsoft Academic Search

Vesicles of egg yolk phosphatidylcholine (EYPC) were studied by cryo-transmission electron microscopy. The electron micrographs indicate that, despite the rapidity of cooling, membrane undulations are flattened and some vesicles change their shapes before the samples freeze. These artefacts are attributed to the action of the lateral tension that results from the membrane area contraction associated with the temperature drop. Other

Beate Klösgen; Wolfgang Helfrich

1993-01-01

381

Technical Assessment of Cryo-Compressed Hydrogen Storage Tank Systems for Automotive Applications.  

National Technical Information Service (NTIS)

On-board and off-board performance and cost of cryo-compressed hydrogen storage has been assessed and compared to the DOE 2010, 2015 and ultimate targets for automotive applications. The Gen-3 prototype system of Lawrence Livermore National Laboratory was...

J. Sinha J. K. Peng K. McKenney R. K. Ahluwalia S. Lasher T. Q. Hua

2009-01-01

382

Cryomesh(TM): A new substrate for cryo-electron microscopy  

PubMed Central

Here we evaluate a new grid substrate developed by ProtoChips Inc. for cryo-transmission electron microscopy. The new grids are fabricated from doped silicon carbide using processes adapted from the semi-conductor industry. A major motivating purpose in the development of these grids was to increase the low-temperature conductivity of the substrate, a characteristic that is thought to affect the appearance of beam-induced movement (BIM) in TEM images of biological specimens. BIM degrades the quality of data, and is especially severe when frozen biological specimens are tilted in the microscope. Our results show that this new substrate does indeed have a significant impact on reducing the appearance and severity of beam-induced movement in TEM images of tilted cryo-preserved samples. Furthermore, while we have not been able to ascertain the exact causes underlying the BIM phenomenon, we have evidence that the rigidity and flatness of these grids may play a major role in its reduction. This improvement in the reliability of imaging at tilt has a significant impact on using data collection methods such as random conical tilt or orthogonal tilt reconstruction with cryo-preserved samples. Reduction in BIM also has the potential for improving the resolution of 3D cryo-reconstructions in general.

Yoshioka, Craig; Carragher, Bridget; Potter, Clint

2010-01-01

383

Whole Cell Cryo-Electron Tomography Reveals Distinct Disassembly Intermediates of Vaccinia Virus  

PubMed Central

At each round of infection, viruses fall apart to release their genome for replication, and then reassemble into stable particles within the same host cell. For most viruses, the structural details that underlie these disassembly and assembly reactions are poorly understood. Cryo-electron tomography (cryo-ET), a unique method to investigate large and asymmetric structures at the near molecular resolution, was previously used to study the complex structure of vaccinia virus (VV). Here we study the disassembly of VV by cryo-ET on intact, rapidly frozen, mammalian cells, infected for up to 60 minutes. Binding to the cell surface induced distinct structural rearrangements of the core, such as a shape change, the rearrangement of its surface spikes and de-condensation of the viral DNA. We propose that the cell surface induced changes, in particular the decondensation of the viral genome, are a prerequisite for the subsequent release of the vaccinia DNA into the cytoplasm, which is followed by its cytoplasmic replication. Generally, this is the first study that employs whole cell cryo-ET to address structural details of pathogen-host cell interaction.

Cyrklaff, Marek; Linaroudis, Alexandros; Boicu, Marius; Chlanda, Petr; Baumeister, Wolfgang; Griffiths, Gareth; Krijnse-Locker, Jacomine

2007-01-01

384

Cryo-Tracker® Mass Gauging System Testing in a Launch Vehicle Simulation  

NASA Astrophysics Data System (ADS)

Sierra Lobo successfully tested its patented Cryo-Tracker® probe and mass gauging system in an Expendable Launch Vehicle (ELV) liquid oxygen tank simulation for NASA's Launch Service Providers Directorate. The effort involved collaboration between Sierra Lobo, NASA Kennedy Space Center (KSC), and Lockheed Martin personnel. Testing simulated filling and expulsion operations of Lockheed Martin's Atlas V liquid oxygen (LOX) tank and characterized the 10.06 m (33-ft) Cryo-Tracker's performance. Sierra Lobo designed a 9.14 m (30-ft) tall liquid nitrogen test tank to simulate the Atlas V LOX tank flow conditions and validate Cryo-Tracker® data via other sensors and visualization. This test package was fabricated at Sierra Lobo's Cryogenics Testbed at NASA KSC. All test objectives were met or exceeded. Key accomplishments include: fabrication of the longest Cryo-Tracker® probe to date; installation technique proven with only two attachment points at top and bottom of tank; probe survived a harsh environment with no loss of signal or structural integrity; probe successfully measured liquid levels and temperatures under all conditions and successfully demonstrated its feasibility as an engine cut-off signal.

Schieb, Daniel J.; Haberbusch, Mark S.; Yeckley, Alexander J.

2006-04-01

385

Direct electron detection yields cryo-EM reconstructions at resolutions beyond 3/4 Nyquist frequency  

PubMed Central

One limitation in electron cryo-microscopy (cryo-EM) is the inability to recover high-resolution signal from the image-recording media at the full-resolution limit of the transmission electron microscope. Direct electron detection using CMOS-based sensors for digitally recording images has the potential to alleviate this shortcoming. Here, we report a practical performance evaluation of a Direct Detection Device (DDD) for biological cryo-EM at two different microscope voltages: 200 and 300 kV. Our DDD images of amorphous and graphitized carbon show strong per-pixel contrast with image resolution near the theoretical sampling limit of the data. Single-particle reconstructions of two frozen-hydrated bacteriophages, P22 and ?15, establish that the DDD is capable of recording usable signal for 3-D reconstructions at about 4/5 of the Nyquist frequency, which is a vast improvement over the performance of conventional imaging media. We anticipate the unparalleled performance of this digital recording device will dramatically benefit cryo-EM for routine tomographic and single-particle structural determination of biological specimens.

Bammes, Benjamin E.; Rochat, Ryan H.; Jakana, Joanita; Chen, Dong-Hua; Chiu, Wah

2012-01-01

386

Direct Visualization of HIV-1 with Correlative Live-Cell Microscopy and Cryo-Electron Tomography  

PubMed Central

SUMMARY Cryo-electron tomography (cryoET) allows 3D visualization of cellular structures at molecular resolution in a close-to-native state, and therefore has the potential to help elucidate early events of HIV-1 infection in host cells. However, direct observation of structural details of infecting HIV-1 has not been realized due to technological challenges in working with rare and dynamic HIV-1 particles in human cells. Here, we report structural analysis of HIV-1 and host-cell interactions by developing a correlative high-speed 3D live-cell imaging and cryoET method. Using this methodology, we showed, for the first time under near-native conditions, that intact hyperstable mutant HIV-1 cores are released into the cytoplasm of host-cells. We further obtained direct evidence to suggest that a hyperstable mutant capsid, E45A, delayed capsid disassembly compared to the wild-type capsid. Together, these results demonstrate the advantage of our correlative live-cell and cryoET approach to image dynamic processes, such as viral infection.

Jun, Sangmi; Ke, Danxia; Debiec, Karl; Zhao, Gongpu; Meng, Xin; Ambrose, Zandrea; Gibson, Gregory A.; Watkins, Simon C.; Zhang, Peijun

2011-01-01

387

Structure of intact Thermus thermophilus V-ATPase by cryo-EM reveals organization of the membrane-bound VO motor  

PubMed Central

The eubacterium Thermus thermophilus uses a macromolecular assembly closely related to eukaryotic V-ATPase to produce its supply of ATP. This simplified V-ATPase offers several advantages over eukaryotic V-ATPases for structural analysis and investigation of the mechanism of the enzyme. Here we report the structure of the complex at ?16 ? resolution as determined by single particle electron cryomicroscopy (cryo-EM). The resolution of the map and our use of cryo-EM, rather than negative stain EM, reveals detailed information about the internal organization of the assembly. We could separate the map into segments corresponding to subunits A and B, the threefold pseudosymmetric C-subunit, a central rotor consisting of subunits D and F, the L-ring, the stator subcomplex consisting of subunits I, E, and G, and a micelle of bound detergent. The architecture of the VO region shows a remarkably small area of contact between the I-subunit and the ring of L-subunits and is consistent with a two half-channel model for proton translocation. The arrangement of structural elements in VO gives insight into the mechanism of torque generation from proton translocation.

Lau, Wilson C. Y.; Rubinstein, John L.

2010-01-01

388

Imaging system for creating 3D block-face cryo-images of whole mice  

NASA Astrophysics Data System (ADS)

We developed a cryomicrotome/imaging system that provides high resolution, high sensitivity block-face images of whole mice or excised organs, and applied it to a variety of biological applications. With this cryo-imaging system, we sectioned cryo-preserved tissues at 2-40 ?m thickness and acquired high resolution brightfield and fluorescence images with microscopic in-plane resolution (as good as 1.2 ?m). Brightfield images of normal and pathological anatomy show exquisite detail, especially in the abdominal cavity. Multi-planar reformatting and 3D renderings allow one to interrogate 3D structures. In this report, we present brightfield images of mouse anatomy, as well as 3D renderings of organs. For BPK mice model of polycystic kidney disease, we compared brightfield cryo-images and kidney volumes to MRI. The color images provided greater contrast and resolution of cysts as compared to in vivo MRI. We note that color cryo-images are closer to what a researcher sees in dissection, making it easier for them to interpret image data. The combination of field of view, depth of field, ultra high resolution and color/fluorescence contrast enables cryo-image volumes to provide details that cannot be found through in vivo imaging or other ex vivo optical imaging approaches. We believe that this novel imaging system will have applications that include identification of mouse phenotypes, characterization of diseases like blood vessel disease, kidney disease, and cancer, assessment of drug and gene therapy delivery and efficacy and validation of other imaging modalities.

Roy, Debashish; Breen, Michael; Salvado, Olivier; Heinzel, Meredith; McKinley, Eliot; Wilson, David

2006-03-01

389

Limiting factors in atomic resolution cryo electron microscopy: No simple tricks  

PubMed Central

To bring cryo electron microscopy (cryoEM) of large biological complexes to atomic resolution, several factors – in both cryoEM image acquisition and 3D reconstruction – that may be neglected at low resolution become significantly limiting. Here we present thorough analyses of four limiting factors: (a) electron-beam tilt, (b) inaccurate determination of defocus values, (c) focus gradient through particles, and (d) particularly for large particles, dynamic (multiple) scattering of electrons. We also propose strategies to cope with these factors: (a) the divergence and direction tilt components of electron-beam tilt could be reduced by maintaining parallel illumination and by using a coma-free alignment procedure, respectively. Moreover, the effect of all beam tilt components, including spiral tilt, could be eliminated by use of a spherical aberration corrector. (b) More accurate measurement of defocus value could be obtained by imaging areas adjacent to the target area at high electron dose and by measuring the image shift induced by tilting the electron beam. (c) Each known Fourier coefficient in the Fourier transform of a cryoEM image is the sum of two Fourier coefficients of the 3D structure, one on each of two curved ‘characteristic surfaces’ in 3D Fourier space. We describe a simple model-based iterative method that could recover these two Fourier coefficients on the two characteristic surfaces. (d) The effect of dynamic scattering could be corrected by deconvolution of a transfer function. These analyses and our proposed strategies offer useful guidance for future experimental designs targeting atomic resolution cryoEM reconstruction.

Zhang, Xing; Zhou, Z. Hong

2013-01-01

390

Strain-induced oxygen defect formation and interfacial magnetic phase separation in SrTiO3(001)/La1-xSrxCoO3  

NASA Astrophysics Data System (ADS)

The remarkable functionality and epitaxial compatibility of complex oxides provides many opportunities for new physics and applications in oxide heterostructures. Perovskite manganites and cobaltites provide excellent examples, being of interest for solid oxide fuel cells, catalysis, ferroelectric RAM, gas sensing, resistive switching memory, and oxide spintronics. However, the same delicate balance between phases that provides this diverse functionality also leads to a serious problem - the difficulty of maintaining desired properties close to the interface with other oxides. Although this problem is widespread, manifests itself in several ways, and could present a significant roadblock to the development of heterostructured devices for oxide electronics, there is no consensus as to its origin, or even whether it is driven by electronic or chemical effects. In this work, using SrTiO3(001)/La1-xSrxCoO3 as a model system, we have combined epitaxial growth via high pressure oxygen sputtering with high resolution x-ray diffraction, atomic resolution electron microscopy and spectroscopy, and detailed magnetic, transport, and neutron scattering measurements to determine the fundamental origin of the deterioration in interfacial transport and magnetism. The effect is found to be due to nanoscopic magnetic phase separation in the near-interface region driven by a significant depletion in interfacial hole doping due to accumulation of O vacancies. This occurs due to a novel mechanism for accommodation of lattice mismatch with the substrate based on formation and long-range ordering of O vacancies, thus providing a fundamental link between strain state and O vacancy density. Further impacts of the O vacancy ordering and interfacial magnetic phase separation, such as formation of a spin-state superlattice and an extraordinary coercivity enhancement, will also be discussed. Work in collaboration with M. Sharma, M. Torija, J. Schmitt, C. He, S. El-Khatib, J. Gazquez, M. Varela, M. Laver and J. Borchers.

Leighton, Chris

2012-02-01

391

Possible magnetic phase separation in Ru-doped La 0.67Ca 0.33MnO 3  

Microsoft Academic Search

X-ray diffraction, resistivity, AC susceptibility and magnetization studies on La0.67Ca0.33Mn1?xRuxO3 (0?x<0.085) were carried out. A significant increase in the lattice parameters indicated the presence of mixed valence state of Ru: Ru3+ and Ru4+. The resistivity of the doped compounds exhibited two features: a broad hump and a relatively sharp peak. While a para- to ferromagnetic transition could be observed for

L. Seetha Lakshmi; V. Sridharan; D. V. Natarajan; Sharat Chandra; V. Sankara Sastry; T. S. Radhakrishnan; Ponn Pandian; R. Justine Joseyphus; A. Narayanasamy

2003-01-01

392

The general concept of signal–noise separation (SNS): mathematical aspects and implementation in magnetic resonance spectroscopy  

Microsoft Academic Search

Magnetic resonance spectroscopy (MRS) and spectroscopic imaging (MRSI) are increasingly recognized as potentially key modalities\\u000a in cancer diagnostics. It is, therefore, urgent to overcome the shortcomings of current applications of MRS and MRSI. We explain\\u000a and substantiate why more advanced signal processing methods are needed, and demonstrate that the fast Padé transform (FPT),\\u000a as the quotient of two polynomials, is

Dževad Belki?; Karen Belki?

2009-01-01

393

Magnetically-Separable and Highly-Stable Enzyme System Based on Crosslinked Enzyme Aggregates Shipped in Magnetite-Coated Mesoporous Silica  

SciTech Connect

Magnetically-separable and highly-stable enzyme system was developed by adsorption of enzymes in superparamagnetic hierarchically ordered mesocellular mesoporous silica (M-HMMS) and subsequent enzyme crosslinking. Superparamagnetic nanoparticles were homogeneously incorporated into hierarchically-ordered mesocellular mesoporous silica (HMMS) by the decomposition of preformed iron propionate complex. The size of incorporated superparamagnetic 15 nanoparticles was around 5 nm, generating a magnetically separable host with high pore volumes and large pores (M-HMMS). ?-chymotrypsin (CT) was adsorbed into M-HMMS with high loading (~30 wt%) in less than 30 minutes. Glutaraldehyde (GA) treatment of adsorbed CT resulted in nanometer scale crosslinked enzyme aggregates in M-HMMS (CLEA-M). The activity of these CT aggregates in M-HMMS (CLEA-M-CT) was 34 times than that of simply adsorbed CT in M20 HMMS, due to an effective prevention of enzyme leaching during washing via a ship-in-a-bottle approach. CLEA-M-CT maintained the intial activity not only under shaking (250 rpm) for 30 days, but also under recycled uses of 35 times. The same approach was employed for the synthesis of CLEA-M of lipase (CLEA-M-LP), and proven to be effective in improving the loading, activity, and stability of enzyme when compared to those of adsorbed LP in M-HMMS.

Lee, Jinwoo; Na, Hyon Bin; Kim, Byoung Chan; Lee, Jin Hyung; Lee, Byoungsoo; Kwak, Ja Hun; Hwang, Yosun; Park, Je-Geun; Gu, Man Bock; Kim, Jaeyun; Joo, Jin; Shin, Chae-Ho; Grate, Jay W.; Hyeon, Taeghwan; Kim, Jungbae

2009-10-15

394

Phase separation in Fe-Si and Co-Si sputtered ferromagnetic alloys and the origin of their magnetic anisotropy  

SciTech Connect

Fe-Si and Co-Si thin films were studied with different Si concentrations by x-ray absorption spectroscopy (XAFS), and the analysis was confronted to their magnetic properties of coercivity and anisotropy. The analysis of the XAFS spectra showed a higher disorder in the amorphous Fe-Si films than in the Co-Si films and a larger degree of clustering of Co atoms, consistent with the higher heat of alloying of Fe-Si with respect to Co-Si alloys. Both kinds of amorphous films contained a strongly disordered silicide phase that was hardly detected by extended XAFS spectroscopy (EXAFS). EXAFS spectra were dominated by the nonmagnetic (Fe,Co)Si{sub 2} environments. The orientation of the magnetic easy axis of the films was correlated with the expected anisotropic spatial distribution of Si concentration, which was defined by the oblique angle of incidence of Si atoms during film deposition. This indicates that such a detected nonmagnetic Si rich environments were anisotropically distributed and possibly segregated, influencing in a significant way the magnetic anisotropy of these films.

Diaz, J.; Morales, R.; Valvidares, S.M.; Alameda, J.M. [Departamento de Fisica, Universidad de Oviedo, Avenida de Calvo Sotelo s/n, Oviedo-33007 (Spain)

2005-10-01

395

Recovery of metals from Cuban nickel tailings by leaching with organic acids followed by precipitation and magnetic separation.  

PubMed

The percolation leaching of the Cuban nickel tailings containing 0.34% Ni, 0.08% Co and 44.2% Fe was investigated by using tartaric and oxalic acids at different concentrations. About 70% Ni, 80% Co and 30% Fe were extracted after 5 days of leaching with the mixture of 0.15 mol/L tartaric acid and 0.05 mol/L oxalic acid at ambient temperature and normal pressure. Nickel and cobalt extraction of 80% as well as iron extraction of 50% were achieved from the pregnant solution by means of precipitation at 80 degrees C for 2h. The precipitation at ambient temperature led to a similar result after 16 days. Cobalt, nickel and iron oxalates were found in the precipitate by using the X-ray diffraction method. The regeneration of acids during the precipitation step made possible the reuse of the raffinate at the leaching step. Heating of the precipitate at 200 degrees C increased the metal concentration to 1.22% Ni and 0.33% Co, which can be fed in the existing nickel plant in Moa, Cuba. The magnetic processing of the leaching residues led to a non-magnetic product containing less than 20% Fe and a magnetic product containing more than 50% Fe. PMID:17084523

Hernández, C M F; Banza, A N; Gock, E

2006-09-23

396

CryoVEx 2011: In-situ sea ice measurements in the high Arctic Ocean for the validation of CryoSat-2 ice thickness retrievals  

NASA Astrophysics Data System (ADS)

The European Space Agency (ESA) CryoSat-2 satellite, which was launched in April 2010, is designed to measure changes in the thickness of the polar ice caps. By means of radar altimetry, CryoSat-2 performs accurate measurements of sea ice freeboard, the height of the ice surface above the water level, which is related to ice thickness via isostasy. From this, ice thickness can be estimated when assumptions are made about the density of snow and ice as well as about the thickness of snow and radar penetration into the snow. There are thus many sources of uncertainty related to the physical properties of snow and ice which may lead to significant errors in the satellite-retrieved ice thickness. Some of these uncertainties can be addressed through in-situ measurements. These were performed during CryoVEx 2011, an international project sponsored and coordinated by ESA and other funding agencies. Three sites with different ice and snow properties were studied between the coast of Ellesmere Island, Canada, and 85.5°N. These sites were visited by Twin Otter airplane landing on unprepared landing strips. At each site, corner reflectors to be used as references for airborne radar altimeter surveys were deployed and marked with drifting GPS buoys, and extensive snow and ice measurements were performed between the corner reflectors. Very high-resolution measurements were carried out in the immediate vicinity of the corner reflectors, including snow pit studies and measurements of radar penetration using a ground-based radar. Subsequently, the sites were overflown by aircraft carrying radar altimeters and ice thickness sensors. This presentation will review the validation concept implemented in the campaign and will summarize the snow and ice properties obtained at the different sites.

Haas, C.; Willatt, R. C.; Laxon, S. W.; Giles, K. A.; Beckers, J.; Hendricks, S.; Davidson, M.

2011-12-01

397

Magnetism  

NSDL National Science Digital Library

This webpage is part of the University Corporation for Atmospheric Research (UCAR) Windows to the Universe program. It describes the nature and configuration of magnetic fields, which are the result of moving electric charges, including how they cause magnetic objects to orient themselves along the direction of the magnetic force points, which are illustrated as lines. Magnetic field lines by convention point outwards at the north magnetic pole and inward at the south magnetic pole. The site features text, scientific illustrations and an animation. Text and vocabulary are selectable for the beginning, intermediate, or advanced reader.

Team, University C.

2007-12-12

398

Prospective randomized study comparing cryo-assisted and needle-wire localization of ultrasound-visible breast tumors  

Microsoft Academic Search

BackgroundThis study compared the surgical results of 2 localization methods—cryo-assisted localization (CAL) and needle-wire localization (NWL)—in patients undergoing breast lumpectomy for breast cancer.

Lorraine Tafra; Richard Fine; Pat Whitworth; Michael Berry; James Woods; Gregory Ekbom; Jennifer Gass; Peter Beitsch; Daleela Dodge; Linda Han; Theodore Potruch; Darius Francescatti; Lori Oetting; J. Stanley Smith; Howard Snider; Donna Kleban; Anees Chagpar; Stephanie Akbari

2006-01-01

399

Crystal and cryoEM structural studies of a cell wall degrading enzyme in the bacteriophage ?29 tail  

PubMed Central

The small bacteriophage ?29 must penetrate the ?250-? thick external peptidoglycan cell wall and cell membrane of the Gram-positive Bacillus subtilis, before ejecting its dsDNA genome through its tail into the bacterial cytoplasm. The tail of bacteriophage ?29 is noncontractile and ?380 ? long. A 1.8-? resolution crystal structure of gene product 13 (gp13) shows that this tail protein has spatially well separated N- and C-terminal domains, whose structures resemble lysozyme-like enzymes and metallo-endopeptidases, respectively. CryoEM reconstructions of the WT bacteriophage and mutant bacteriophages missing some or most of gp13 shows that this enzyme is located at the distal end of the ?29 tail knob. This finding suggests that gp13 functions as a tail-associated, peptidoglycan-degrading enzyme able to cleave both the polysaccharide backbone and peptide cross-links of the peptidoglycan cell wall. Comparisons of the gp13? mutants with the ?29 mature and emptied phage structures suggest the sequence of events that occur during the penetration of the tail through the peptidoglycan layer.

Xiang, Ye; Morais, Marc C.; Cohen, Daniel N.; Bowman, Valorie D.; Anderson, Dwight L.; Rossmann, Michael G.

2008-01-01

400

Crystal and cryoEM structural studies of a cell wall degrading enzyme in the bacteriophage [psi]29 tail  

SciTech Connect

The small bacteriophage {phi}29 must penetrate the {approx}250-{angstrom} thick external peptidoglycan cell wall and cell membrane of the Gram-positive Bacillus subtilis, before ejecting its dsDNA genome through its tail into the bacterial cytoplasm. The tail of bacteriophage {phi}29 is noncontractile and {approx}380 {angstrom} long. A 1.8-{angstrom} resolution crystal structure of gene product 13 (gp13) shows that this tail protein has spatially well separated N- and C-terminal domains, whose structures resemble lysozyme-like enzymes and metallo-endopeptidases, respectively. CryoEM reconstructions of the WT bacteriophage and mutant bacteriophages missing some or most of gp13 shows that this enzyme is located at the distal end of the {phi}29 tail knob. This finding suggests that gp13 functions as a tail-associated, peptidoglycan-degrading enzyme able to cleave both the polysaccharide backbone and peptide cross-links of the peptidoglycan cell wall. Comparisons of the gp13{sup -} mutants with the {phi}29 mature and emptied phage structures suggest the sequence of events that occur during the penetration of the tail through the peptidoglycan layer.

Xiang, Ye; Morais, Marc C.; Cohen, Daniel N.; Bowman, Valorie D.; Anderson, Dwight L.; Rossmann, Michael G. (Purdue); (UMM)

2009-08-28

401

Efficient separation and sensitive detection of Listeria monocytogenes using an impedance immunosensor based on magnetic nanoparticles, a microfluidic chip, and an interdigitated microelectrode.  

PubMed

Listeria monocytogenes continues to be a major foodborne pathogen that causes food poisoning, and sometimes death, among immunosuppressed people and abortion among pregnant women. In this study, magnetic nanoparticles with a diameter of 30 nm were functionalized with anti-L. monocytogenes antibodies via biotin-streptavidin bonds to become immunomagnetic nanoparticles (IMNPs) to capture L. monocytogenes in a sample during a 2-h immunoreaction. A magnetic separator was used to collect and hold the IMNPs-L. monocytogenes complex while the supernatants were removed. After the washing step, the nanoparticle-L. monocytogenes complex was separated from the sample and injected into a microfluidic chip. The impedance change caused by L. monocytogenes was measured by an impedance analyzer through the interdigitated microelectrode in the microfluidic chip. For L. monocytogenes in phosphate-buffered saline solution, up to 75% of the cells in the sample could be separated, and as few as three to five cells in the microfluidic chip could be detected, which is equivalent to 10(3) CFU/ml of cells in the original sample. The detection of L. monocytogenes was not interfered with by other major foodborne bacteria, including E. coli O157:H7, E. coli K-12, L. innocua, Salmonella Typhimurium, and Staphylococcus aureus. A linear correlation (R(2) = 0.86) was found between the impedance change and the number of L. monocytogenes in a range of 10(3) to 10(7) CFU/ml. Equivalent circuit analysis indicated that the impedance change was mainly due to the decrease in medium resistance when the IMNPs-L. monocytogenes complexes existed in mannitol solution. Finally, the immunosensor was evaluated with food sample tests; the results showed that, without preenrichment and labeling, 10(4) and 10(5) CFU/ml L. monocytogenes in lettuce, milk, and ground beef samples could be detected in 3 h. PMID:23127703

Kanayeva, Damira A; Wang, Ronghui; Rhoads, Douglas; Erf, Gisela F; Slavik, Michael F; Tung, Steve; Li, Yanbin

2012-11-01

402

Cryo-cooler development for space flight applications  

NASA Astrophysics Data System (ADS)

Several types of cryogenic cooling systems for the focal planes and optical elements in sensors aboard orbiting spacecraft have been developed. (1) The cryogenic radiator is very reliable and requires no power consumption although it does not cool below 40 K and has a limited capacity. (2) The Vuilleumier cooler has moderate efficiency but it is difficult to detach the cold section and there is a problem of wearing parts. (3) The turbo-cooler has gas film bearings, a detached cold section and a large cooling capacity, but has poor efficiency in small sizes. (4) The rotary reciprocating refrigerator has good efficiency, little vibration and a detached cold section, but it is a complex machine with complex electronics. (5) The Stirling cooler with magnetic bearings and clearance seals is highly efficient but requires a counter-mass balance system and complex electronics for its magnetic bearings.

Harris, R. E.; Chenoweth, J. E.; White, R.

1981-01-01

403

Synthesis of chitosan networks: Swelling, drug release, and magnetically assisted BSA separation using Fe3O4 nanoparticles.  

PubMed

Chitosan (CS) nanohydrogel networks were prepared by reaction with glyceroldiglycidylether (GDE) and poly(dimethylsiloxane) (PDMS), as crosslinking agents in an emulsion system. The nanogel content increased with increasing the amount of crosslinkers and reached to a maximum of 90% with GDE. The nanogels structure was characterized by FT-IR, AFM, DSC, and TGA. The average size for CS-GDE and CS-PDMS particles were 59nm and 180nm, respectively. The swelling behavior of nanohydrogels was observed to be dependent on pH, temperature, degree of crosslinking, and on the chemical structure of crosslinker. The equilibrium water content of CS-GDE nanohydrogels reached to a maximum of 600% at neutral pH, and decreased at high and low pH and low temperature. These nanohydrogels were tested for sodium diclofenac (SDF) loading and releasing efficiency. The covalent conjugation of bovine serum albumin (BSA) and magnetic Fe(3)O(4) nanoparticles on the hydrogels were found to hold a potential application in magnetically assisted bioseparation. PMID:22939340

Ghaemy, Mousa; Naseri, Motahare

2012-07-02

404

3D structure of eukaryotic flagella in a quiescent state revealed by cryo-electron tomography.  

PubMed

We have used cryo-electron tomography to investigate the 3D structure and macromolecular organization of intact, frozen-hydrated sea urchin sperm flagella in a quiescent state. The tomographic reconstructions provide information at a resolution better than 6 nm about the in situ arrangements of macromolecules that are key for flagellar motility. We have visualized the heptameric rings of the motor domains in the outer dynein arm complex and determined that they lie parallel to the plane that contains the axes of neighboring flagellar microtubules. Both the material associated with the central pair of microtubules and the radial spokes display a plane of symmetry that helps to explain the planar beat pattern of these flagella. Cryo-electron tomography has proven to be a powerful technique for helping us understand the relationships between flagellar structure and function and the design of macromolecular machines in situ. PMID:16246999

Nicastro, Daniela; McIntosh, J Richard; Baumeister, Wolfgang

2005-10-24

405

3D structure of eukaryotic flagella in a quiescent state revealed by cryo-electron tomography  

PubMed Central

We have used cryo-electron tomography to investigate the 3D structure and macromolecular organization of intact, frozen-hydrated sea urchin sperm flagella in a quiescent state. The tomographic reconstructions provide information at a resolution better than 6 nm about the in situ arrangements of macromolecules that are key for flagellar motility. We have visualized the heptameric rings of the motor domains in the outer dynein arm complex and determined that they lie parallel to the plane that contains the axes of neighboring flagellar microtubules. Both the material associated with the central pair of microtubules and the radial spokes display a plane of symmetry that helps to explain the planar beat pattern of these flagella. Cryo-electron tomography has proven to be a powerful technique for helping us understand the relationships between flagellar structure and function and the design of macromolecular machines in situ.

Nicastro, Daniela; McIntosh, J. Richard; Baumeister, Wolfgang

2005-01-01

406

Noise models and cryo-EM drift correction with a direct-electron camera.  

PubMed

Blurring due to specimen-holder drift is a common occurrence in cryo-EM images. Cameras employing active-pixel sensors are capable of high frame rates such that a single low-dose exposure can be acquired as a series of frames. In this paper we consider the possibility of tracking and compensating for overall drift in typical single-particle specimens through the analysis of frame sequences. A problem that arises in tracking through cross-correlation of frames obtained with the DE-12 camera from Direct Electron LLC is the presence of "hot-pixel noise". This random pattern of bright pixels is highly correlated among frames. We show how a model of this noise can be employed to greatly reduce its effects. A filter function is derived that optimizes the tracking of image shifts by cross-correlation, and we demonstrate the tracking of specimen drift in typical cryo-EM specimens. PMID:23748163

Shigematsu, H; Sigworth, F J

2013-04-18

407

4.4 ? cryo-EM structure of an enveloped alphavirus Venezuelan equine encephalitis virus  

PubMed Central

Venezuelan equine encephalitis virus (VEEV), a member of the membrane-containing Alphavirus genus, is a human and equine pathogen, and has been developed as a biological weapon. Using electron cryo-microscopy (cryo-EM), we determined the structure of an attenuated vaccine strain, TC-83, of VEEV to 4.4 Å resolution. Our density map clearly resolves regions (including E1, E2 transmembrane helices and cytoplasmic tails) that were missing in the crystal structures of domains of alphavirus subunits. These new features are implicated in the fusion, assembly and budding processes of alphaviruses. Furthermore, our map reveals the unexpected E3 protein, which is cleaved and generally thought to be absent in the mature VEEV. Our structural results suggest a mechanism for the initial stage of nucleocapsid core formation, and shed light on the virulence attenuation, host recognition and neutralizing activities of VEEV and other alphavirus pathogens.

Zhang, Rui; Hryc, Corey F; Cong, Yao; Liu, Xiangan; Jakana, Joanita; Gorchakov, Rodion; Baker, Matthew L; Weaver, Scott C; Chiu, Wah

2011-01-01

408

Model of human low-density lipoprotein and bound receptor based on CryoEM  

PubMed Central

Human plasma low-density lipoproteins (LDL), a risk factor for cardiovascular disease, transfer cholesterol from plasma to liver cells via the LDL receptor (LDLr). Here, we report the structures of LDL and its complex with the LDL receptor extracellular domain (LDL·LDLr) at extracellular pH determined by cryoEM. Difference imaging between LDL·LDLr and LDL localizes the site of LDLr bound to its ligand. The structural features revealed from the cryoEM map lead to a juxtaposed stacking model of cholesteryl esters (CEs). High density in the outer shell identifies protein-rich regions that can be accounted for by a single apolipoprotein (apo B-100, 500 kDa) leading to a model for the distribution of its ?-helix and ?-sheet rich domains across the surface. The structural relationship between the apo B-100 and CEs appears to dictate the structural stability and function of normal LDL.

Ren, Gang; Rudenko, Gabby; Ludtke, Steven J.; Deisenhofer, Johann; Chiu, Wah; Pownall, Henry J.

2010-01-01

409

Cryo-electron tomography: moving towards revealing the viral life cycle of Rice dwarf virus.  

PubMed

It is well known that viruses utilize the host cellular systems for their infection and replication processes. However, the molecular mechanisms underlying these processes are poorly understood for most viruses. To understand these molecular mechanisms, it is essential to observe the viral and virus-related structures and analyse their molecular interactions within a cellular context. Cryo-electron microscopy and tomography offer the potential to observe macromolecular structures and to analyse their molecular interactions within the cell. Here, using cryo-electron microscopy and tomography, the structures of Rice dwarf virus are reported within fully hydrated insect vector cells grown on electron microscopy grids towards revealing the viral infection and replication mechanisms. PMID:24121321

Miyazaki, Naoyuki; Akita, Fusamichi; Nakagawa, Atsushi; Murata, Kazuyoshi; Omura, Toshihiro; Iwasaki, Kenji

2013-10-02

410

Cross-linking cellulose nanofibrils for potential elastic cryo-structured gels  

NASA Astrophysics Data System (ADS)

Cellulose nanofibrils were produced from P. radiata kraft pulp fibers. The nanofibrillation was facilitated by applying 2,2,6,6-tetramethylpiperidinyl-1-oxyl-mediated oxidation as pretreatment. The oxidized nanofibrils were cross-linked with polyethyleneimine and poly N-isopropylacrylamide- co-allylamine- co-methylenebisacrylamide particles and were frozen to form cryo-structured gels. Samples of the gels were critical-point dried, and the corresponding structures were assessed with scanning electron microscopy. It appears that the aldehyde groups in the oxidized nanofibrils are suitable reaction sites for cross-linking. The cryo-structured materials were spongy, elastic, and thus capable of regaining their shape after a given pressure was released, indicating a successful cross-linking. These novel types of gels are considered potential candidates in biomedical and biotechnological applications.

Syverud, Kristin; Kirsebom, Harald; Hajizadeh, Solmaz; Chinga-Carrasco, Gary

2011-12-01

411

Cross-linking cellulose nanofibrils for potential elastic cryo-structured gels  

PubMed Central

Cellulose nanofibrils were produced from P. radiata kraft pulp fibers. The nanofibrillation was facilitated by applying 2,2,6,6-tetramethylpiperidinyl-1-oxyl-mediated oxidation as pretreatment. The oxidized nanofibrils were cross-linked with polyethyleneimine and poly N-isopropylacrylamide-co-allylamine-co-methylenebisacrylamide particles and were frozen to form cryo-structured gels. Samples of the gels were critical-point dried, and the corresponding structures were assessed with scanning electron microscopy. It appears that the aldehyde groups in the oxidized nanofibrils are suitable reaction sites for cross-linking. The cryo-structured materials were spongy, elastic, and thus capable of regaining their shape after a given pressure was released, indicating a successful cross-linking. These novel types of gels are considered potential candidates in biomedical and biotechnological applications.

2011-01-01

412

CRYO-ELECTRON MICROSCOPY DATA DENOISING BASED ON THE GENERALIZED DIGITIZED TOTAL VARIATION METHOD  

PubMed Central

The energy functional used in digitalized total variation method is expanded to a general form and a generalized digitized total variation (GDTV) denoising method is obtained. We further expand this method from 2-dimensional (2D) image to 3-dimensional (3D) image processing field. Cryo-electron microscopy (cryo EM) and single particle reconstruction are becoming part of standard collection of structural techniques used for studying macromolecular assemblies. Howerver, the 3D data obtained suffers greatly from noise and degradation for the low dose electron radiation. Thus, image enhancement and noise reduction are theoretically necessary to improve the data for the subsequent segmentation and/or structure skeletonization. Although there are several methods to tackle this problem, we are pleased to find that GDTV method is very efficient and can achieve better performance. Comparative experiments are carried out to verify the enhancement achieved by the GDTV method.

ZHANG, QIN; BAJAJ, CHANDRAJIT L.

2010-01-01

413

Opening windows into the cell: focused-ion-beam milling for cryo-electron tomography.  

PubMed

Cryo-electron tomography (CET) is ideally suited for bridging the resolution gap between molecular and cellular structural studies. However, CET is limited to a sample thickness under 500nm, which is thinner than most cells. Here, we review a method for preparing cells for CET using focused-ion-beam milling, a technique commonly used in materials science. Adapted to cryogenic conditions, FIB milling can be applied to various cell types to produce samples thin enough for CET that do not present the artefacts typical to other preparation techniques, for example, cryo-ultramicrotomy, effectively opening windows into intact cells. Samples can be produced routinely and reproducibly. The data obtained from CET can be used for structural studies in situ, or to do quantitative cell biology studies, in which cells can be observed at the molecular level under different physiological conditions. PMID:24090931

Villa, Elizabeth; Schaffer, Miroslava; Plitzko, Jürgen M; Baumeister, Wolfgang

2013-09-30

414

A lumped-parameter model for cryo-adsorber hydrogen storage tank  

Microsoft Academic Search

One of the primary requirements for commercialization of hydrogen fuel-cell vehicles is the on-board storage of hydrogen in sufficient quantities. On-board storage of hydrogen by adsorption on nano-porous adsorbents at around liquid nitrogen temperatures and moderate pressures is considered viable and competitive with other storage technologies: liquid hydrogen, compressed gas, and metallic or complex hydrides. The four cryo-adsorber fuel tank

V. Senthil Kumar; K. Raghunathan; Sudarshan Kumar

2009-01-01

415

Technical assessment of cryo-compressed hydrogen storage tank systems for automotive applications  

Microsoft Academic Search

On-board and off-board performance and cost of cryo-compressed hydrogen storage has been assessed and compared to the DOE 2010, 2015 and ultimate targets for automotive applications. The Gen-3 prototype system of Lawrence Livermore National Laboratory was modeled to project the performance of a scaled-down 5.6-kg usable hydrogen storage system. The on-board performance of the system and high-volume manufacturing cost were

R. K. Ahluwalia; T. Q. Hua; J.-K. Peng; S. Lasher; K. McKenney; J. Sinha; TIAX LLC

2010-01-01

416

Technical assessment of cryo-compressed hydrogen storage tank systems for automotive applications  

Microsoft Academic Search

On-board and off-board performance and cost of cryo-compressed hydrogen storage are assessed and compared to the targets for automotive applications. The on-board performance of the system and high-volume manufacturing cost were determined for liquid hydrogen refueling with a single-flow nozzle and a pump that delivers liquid H2 to the insulated cryogenic tank capable of being pressurized to 272atm. The off-board

R. K. Ahluwalia; T. Q. Hua; J.-K. Peng; S. Lasher; K. McKenney; J. Sinha; M. Gardiner; TIAX LLC

2010-01-01

417

Practical performance evaluation of a 10k x 10k CCD for electron cryo-microscopy  

PubMed Central

Electron cryo-microscopy (cryo-EM) images are commonly collected using either charge-coupled devices (CCD) or photographic film. Both film and the current generation of 16 megapixel (4k × 4k) CCD cameras have yielded high-resolution structures. Yet, despite the many advantages of CCD cameras, more than two times as many structures of biological macromolecules have been published in recent years using photographic film. The continued preference to film, especially for subnanometer-resolution structures, may be partially influenced by the finer sampling and larger effective specimen imaging area offered by film. Large format digital cameras may finally allow them to overtake film as the preferred detector for cryo-EM. We have evaluated a 111-megapixel (10k × 10k) CCD camera with a 9 ?m pixel size. The spectral signal-to-noise ratios of low dose images of carbon film indicate that this detector is capable of providing signal up to at least 2/5 Nyquist frequency potentially retrievable for 3-D reconstructions of biological specimens, resulting in more than double the effective specimen imaging area of existing 4k × 4k CCD cameras. We verified our estimates using frozen-hydrated ?15 bacteriophage as a biological test specimen with previously determined structure, yielding a ~7 Å resolution single particle reconstruction from only 80 CCD frames. Finally, we explored the limits of current CCD technology by comparing the performance of this detector to various CCD cameras used for recording data yielding subnanometer resolution cryo-EM structures submitted to the Electron Microscopy Data Bank (http://www.emdatabank.org/).

Bammes, Benjamin E.; Rochat, Ryan H.; Jakana, Joanita; Chiu, Wah

2011-01-01

418

Multiple Oligomeric States of the Helicobacter pylori Vacuolating Toxin Demonstrated by Cryo-electron Microscopy  

Microsoft Academic Search

Helicobacter pylori vacuolating toxin (VacA) is a bacterial protein toxin that forms water-soluble oligomeric complexes, and can somehow insert into lipid bilayers to produce anion-selective channels. In this study, we utilize the novel technique of “cryo-negative staining” to examine the morphology of vitrified VacA complexes. Two basic types of oligomeric structures were observed: (i) relatively thick six or seven-sided astral

Marc Adrian; Jacques Dubochet; John E. Heuser

2002-01-01

419

Cryo Cooler Induced MicroVibration Disturbances to the Hubble Space Telescope  

Microsoft Academic Search

This paper presents an overview of the Hubble Space Telescope (HST) Near Infrared Camera and Multi-Object Spectrometer (NICMOS) Cryo Cooler (NCC) system, a description of the micro-vibration characterization testing performed, and a discussion of the simulated performance. The NCC is a reverse Brayton cycle system that employs micro turbo-machinery to provide cooling to the NICMOS instrument. Extensive testing was conducted

N. Jedricha; D. Zimbelmanb; M. Turczync; J. Sillsd; C. Voorheese; B. Clappf

420

Cryo Cooler Induced MicroVibration Disturbances to the Hubble Space Telescope  

Microsoft Academic Search

This paper presents an overview of the Hubble Space Telescope (HST) Near Infrared Camera and Multi-Object Spectrometer (NICMOS) Cryo Cooler (MCC) system, a description of the micro-vibration characterization testing performed, and a discussion of the simulated performance. The NCC is a reverse Brayton cycle system that employs micro turbo-machinery to provide cooling to the NICMOS instrument. Extensive testing was conducted

Nick Jedrich; Darrell Zimbelman; Mark Turczyn; Joel Sills; Carl Voorhees; Brian Clapp

2002-01-01

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