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1

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

2011-07-01

2

A Magnetic Resonance (MR) Microscopy System using a Microfluidically Cryo-Cooled Planar Coil  

PubMed Central

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.

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

2011-01-01

3

A two-stage pulse tube cryo-cooled MRI magnet  

NASA Astrophysics Data System (ADS)

A compact, cryogen-free 0.5 Tesla superconducting Magnetic Resonance Imager (MRI) magnet has been conductively-cooled using a two-stage Pulse Tube cryo-refrigerator. With the absence of cold moving parts and seals, Pulse Tube cryo-refrigerators offer lower transmitted vibrations to a MRI magnet and potentially longer MTBF rates. A 7 kW input power compressor package was connected to the Pulse Tube. The Pulse Tube system provided an estimated 1.3 Watts of cooling power at 4.2 K. Vibration measurements made on the vacuum enclosure could not detect vibration or noise due to cryo-refrigerator operation even in the presence of very low levels of background noise. The cryo-refrigerator has been in continuous operation for >4000 hours without degradation of thermal performance. .

Thompson, P. S.; Ackermann, R. A.; Hedeen, R. A.

2002-05-01

4

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

5

[Separation of magnetic bacteria by using a magnetic separator].  

PubMed

A magnetic separator was used to separate magnetic bacteria based on their magnetotactic characteristics. Acidithiobacillus ferrooxidans, a bacterium that could synthesize intra-cellular nanometer magnetic particles, was investigated as an example. Strong magnetic and weak magnetic cells were separated and collected. On average, the number of the magnetic particles present in the strong magnetic cells is more than that of the weak magnetic cells. Moreover, semisolid-plate magnetophoresis showed that the magnetotaxis of strong magnetic cells was stronger than the weak magnetic cells. These results suggest that the magnetic separator can be used to isolate the magnetic bacteria, which will facilitate the research of magnetic bacteria. PMID:20432949

Liu, Xinxing; Guo, Ning; Yang, Yingjie; Liang, Wanjie; Zhang, Jian

2010-02-01

6

Medical protein separation system using high gradient magnetic separation by superconducting magnet  

NASA Astrophysics Data System (ADS)

A high gradient magnetic separation system for medical protein using affinity magnetic nano-beads has been developed. Medical protein such as monoclonal antibody or immunoglobulin is an important substance as a medicine for cancer etc. However; the separation system of these medical protein has very low separation rate and the cost of product is extremely high. The developed system shows very high separation efficiency and can achieve low cost by large production rate compared to the system now using in this field. The system consists of a 3T superconducting magnet cooled by a cryo-cooler, a filter made of fine magnetic metal wires of about 30?m diameter and a demagnetization circuit and a liquid circulation pump for solvent containing medical protein. Affinity magnetic nano-beads is covered with the medical protein after agitation of solvent containing the protein and nano-beads, then the solvent flows through the system and the beads are trapped in the filters by high gradient magnetic field. The beads are released and flow out of the system by the AC demagnetization of the filters using LC resonance circuits after discharge of the magnet. The test results shows 97.8% of the magnetic nano-beads in pure water were captured and 94.1% of total beads were collected.

Kamioka, Y.; Agatsuma, K.; Kajikawa, K.; Ueda, H.; Furuse, M.; Fuchino, S.; Iitsuka, T.; Nakamura, S.

2014-01-01

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

Industrial Applications of Magnetic Separation.  

National Technical Information Service (NTIS)

The conference convened to provide opportunities for researchers and practitioners to exchange the latest information on research and development in magnetic separation, emphasizing the existing and potential industrial applications of magnetic separation...

Y. A. Liu

1979-01-01

9

A Cryo-Free 10 T High-Field Magnet System for a Novel Superconducting Application—Experimental Results  

Microsoft Academic Search

The experimental results of a cryo-free high-field magnet system for a novel magnetizer are presented. The magnet for the application is a superconducting racetrack coil of 0.7 m length using low AC-loss ${\\\\rm Nb}_{3}{\\\\rm Sn}$ wire from Luvata. The coil selection, reaction, epoxy selection, winding trials and vacuum impregnation are reported in a previous paper. Here the experimental testing of

W. Stautner; S. Mine; K. Sivasubramaniam; J. Rochford; E. Budesheim; K. Amm

2012-01-01

10

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

11

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

12

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

13

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

14

Whole mouse cryo-imaging  

NASA Astrophysics Data System (ADS)

The Case cryo-imaging system is a section and image system which allows one to acquire micron-scale, information rich, whole mouse color bright field and molecular fluorescence images of an entire mouse. Cryo-imaging is used in a variety of applications, including mouse and embryo anatomical phenotyping, drug delivery, imaging agents, metastastic cancer, stem cells, and very high resolution vascular imaging, among many. Cryo-imaging fills the gap between whole animal in vivo imaging and histology, allowing one to image a mouse along the continuum from the mouse -> organ -> tissue structure -> cell -> sub-cellular domains. In this overview, we describe the technology and a variety of exciting applications. Enhancements to the system now enable tiled acquisition of high resolution images to cover an entire mouse. High resolution fluorescence imaging, aided by a novel subtraction processing algorithm to remove sub-surface fluorescence, makes it possible to detect fluorescently-labeled single cells. Multi-modality experiments in Magnetic Resonance Imaging and Cryo-imaging of a whole mouse demonstrate superior resolution of cryo-images and efficiency of registration techniques. The 3D results demonstrate the novel true-color volume visualization tools we have developed and the inherent advantage of cryo-imaging in providing unlimited depth of field and spatial resolution. The recent results continue to demonstrate the value cryo-imaging provides in the field of small animal imaging research.

Wilson, David; Roy, Debashish; Steyer, Grant; Gargesha, Madhusudhana; Stone, Meredith; McKinley, Eliot

2008-04-01

15

Magnetic Separator Enhances Treatment Possibilities  

NASA Technical Reports Server (NTRS)

Since the earliest missions in space, NASA specialists have performed experiments in low gravity. Protein crystal growth, cell and tissue cultures, and separation technologies such as electrophoresis and magnetophoresis have been studied on Apollo 14, Apollo 16, STS-107, and many other missions. Electrophoresis and magnetophoresis, respectively, are processes that separate substances based on the electrical charge and magnetic field of a molecule or particle. Electrophoresis has been studied on over a dozen space shuttle flights, leading to developments in electrokinetics, which analyzes the effects of electric fields on mass transport (atoms, molecules, and particles) in fluids. Further studies in microgravity will continue to improve these techniques, which researchers use to extract cells for various medical treatments and research.

2008-01-01

16

Droplet-based magnetically activated cell separation  

Microsoft Academic Search

In this study, we developed a method that target cells in suspension can be separated by combining magnetic force and gravitation force. Since the newly developed method involves a separating process of a droplet containing nontarget cells in suspension by applying magnetic force to separate target cells, we called it droplet-based magnetic activated cell sorting (dMACS). To demonstrate the efficiency

Y. H. Kim; S. Hong; B. Kim; S. Yun; Y. R. Kang; K. K. Paek; J. W. Lee; S. H. Lee; B. K. Ju

2004-01-01

17

High gradient magnetic separation theory and applications  

Microsoft Academic Search

This paper discusses key technical and economical achievements which have extended the range of application of magnetic separation methods into the commercial processing of micron size feebly magnetic materials. Commercial application of magnetic methods in the cleaning of kaolin clay is reviewed and a discussion of magnetic separation principles is given with emphasis on identification and utilization of important process

R. Oder

1976-01-01

18

A novel magnetic suspension cum linear actuator system for satellite cryo coolers  

SciTech Connect

Stirling cycle cryogenic coolers have been widely used for device cooling in satellites. Various types of magnetic bearings and linear actuators find application in such systems. The most widely used configurations have two-axis-radially-active suspension stations placed at either ends of a reciprocating shaft in the compression and expansion sections. Separate or integral liner motors are provided in each section for axial shaft movement. It may be noted that such configurations are rather complicated and less reliable because of the presence of numerous electro-mechanical components, sensors and electronic servo channels. In this paper, a simple and reliable scheme is suggested which axially stabilizes and linearly perturbs the piston so that the need for a separate motor for axial actuation can be totally dispensed with. The piston is radially supported by passive repulsive bearings. In the axial direction, a servo actuator balances'' the piston and also actuates it bi-directionally. Implemented of this bearing cum motor theme,'' reduces the number of electromechanical and electronic components required to operate the system and hence minimizes the chances of system failure. Apart from this, the system's power consumption is reduced and efficiency is improved as electrical heating losses caused by quiescent-operating currents are removed and electromagnetic losses on the moving parts are minimized. The necessary system parameters have been derived using finite element analysis techniques. Finally, the proposed design is validated by computer-aided system simulation.

Sivadasan, K.K. (Indian Space Research Organization, Trivandrum (India). ISRO Inertial Systems Unit)

1994-05-01

19

Magnetic separation of antibiotics by electrochemical magnetic seeding  

NASA Astrophysics Data System (ADS)

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 using a neodymium magnet. Iron and aluminium anodes were suitable for magnetic seeding of the antibiotics. The results indicated that the ability of antibiotics to form strong complex with iron and aluminium allowed the higher removal by magnetic separation. This method would be appropriate for rapid treatment of antibiotics in wastewater.

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

2009-03-01

20

Microfluidic high gradient magnetic cell separation  

Microsoft Academic Search

Separation of blood cells by native susceptibility and by the selective attachment of magnetic beads has recently been demonstrated on microfluidic devices. We discuss the basic principles of how forces are generated via the magnetic susceptibility of an object and how microfluidics can be combined with micron-scale magnetic field gradients to greatly enhance in principle the fractionating power of magnetic

David W. Inglis; Robert Riehn; James C. Sturm; Robert H. Austin

2006-01-01

21

A magnetic separator for efficient microalgae harvesting.  

PubMed

A magnetic separator, which consisted of permanent magnet drum, separation chamber and scraper blade, was manufactured for efficient microalgae harvesting. The harvesting efficiency of Chlorella ellipsoidea cells reached more than 95% within forty seconds in each batch operation of microalgae harvesting. In the continuous operation of microalgae harvesting, the harvesting efficiency decreased with increasing the liquid flow rate through the separation chamber and remained more than 95% at the liquid flow rate less than 100mL/min. The developed magnetic separator together with functional magnetic nanoparticles provided a promising method for efficient microalgae harvesting in practice. PMID:24656619

Hu, Yi-Ru; Guo, Chen; Xu, Ling; Wang, Feng; Wang, Shi-Kai; Hu, Zanmin; Liu, Chun-Zhao

2014-04-01

22

Magnetic nanoparticles separation based on nanostructures  

Microsoft Academic Search

This study describes a magnetic array, which consists of depositing Fe nanowires on a porous alumina membrane. Such a device can be used as a planar magnetic separator. Its performance for the collection of Fe3O4 nanoparticles is experimentally shown. For magnetization of such iron nanowires in the vertical direction, we propose equations to calculate the theoretical absorption ratio.

Jianfei Sun; Rui Xu; Yu Zhang; Ming Ma; Ning Gu

2007-01-01

23

Magnetic nanoparticles separation based on nanostructures  

NASA Astrophysics Data System (ADS)

This study describes a magnetic array, which consists of depositing Fe nanowires on a porous alumina membrane. Such a device can be used as a planar magnetic separator. Its performance for the collection of Fe 3O 4 nanoparticles is experimentally shown. For magnetization of such iron nanowires in the vertical direction, we propose equations to calculate the theoretical absorption ratio.

Sun, Jianfei; Xu, Rui; Zhang, Yu; Ma, Ming; Gu, Ning

2007-05-01

24

Magnetic Cell Separation with Electrodeposited Nanowires  

Microsoft Academic Search

Ferromagnetic nanowires are demonstrated as an effective tool to apply magnetic forces to cells. The nanowires are made by electrochemical deposition in nanoporous templates, permitting detailed control of their morphology, magnetic properties, and composition. In addition, the nanowires can be functionalized with biologically active molecules based on their surface chemistry. Magnetic cell separations were performed with Ni nanowires 350 nm

A. Hultgren; M. Tanase; E. J. Felton; G. J. Meyer; C. S. Chen; D. H. Reich

2003-01-01

25

A PURPOSE ORIENTED MAGNETIC SEPARATOR: SKIMMER  

SciTech Connect

A magnetic separator was designed to selectively separate fine-liberated magnetite. The conceptual design was simulated using CFD techniques. A separator tank was fabricated and a magnetic drum was used to capture magnetic particles. The initial tank design was modified to eliminate application oriented problems. The new separator was able to produce a fine product as a concentrate at relatively high feed rates. A plant simulation showed that such a device could lower circulating loads around ball mills by 16%, thereby creating room for a 5-8% increase in throughput at the same energy level. However, it was concluded that further improvements in terms of both size and mineral selectivity are needed to have a marketable product.

Salih Ersayin

2005-08-09

26

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 Fe 3O 4 of 20 nm in diameter was trapped in the magnetic filter under an external magnetic field of 0.5 T. Fe 3O 4 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

27

High gradient magnetic separation: Theory versus experiment  

Microsoft Academic Search

The experimental performance of a high gradient magnetic separator has been previously reported by other workers in some detail for a CuO\\/Al2O3slurry. Less detailed results were also reported for slurries of Mn2O3, Al, and ?-Fe2O3particles with Al2O3representing a 20:1 range in particle sizes and a 200:1 range in magnetic susceptibility. Examination of these results indicates that many layers of particles

F. Luborsky; B. Drummond

1975-01-01

28

Rapid Characterization of Magnetic Moment of Cells for Magnetic Separation  

PubMed Central

NCI-H1650 lung cancer cell lines labeled with magnetic nanoparticles via the Epithelial Cell Adhesion Molecule (EpCAM) antigen were previously shown to be captured at high efficiencies by a microfabricated magnetic sifter. If fine control and optimization of the magnetic separation process is to be achieved, it is vital to be able to characterize the labeled cells’ magnetic moment rapidly. We have thus adapted a rapid prototyping method to obtain the saturation magnetic moment of these cells. This method utilizes a cross-correlation algorithm to analyze the cells’ motion in a simple fluidic channel to obtain their magnetophoretic velocity, and is effective even when the magnetic moments of cells are small. This rapid characterization is proven useful in optimizing our microfabricated magnetic sifter procedures for magnetic cell capture.

Ooi, Chinchun; Earhart, Christopher M.; Wilson, Robert J.; Wang, Shan X.

2014-01-01

29

Magnetic Cell Separation with Electrodeposited Nanowires  

NASA Astrophysics Data System (ADS)

Ferromagnetic nanowires are demonstrated as an effective tool to apply magnetic forces to cells. The nanowires are made by electrochemical deposition in nanoporous templates, permitting detailed control of their morphology, magnetic properties, and composition. In addition, the nanowires can be functionalized with biologically active molecules based on their surface chemistry. Magnetic cell separations were performed with Ni nanowires 350 nm in diameter and 5-35 µm long in field gradients of 40 T/m. Single -pass separations of NIH-3T3 cells with 35 µm wires achieve 81with 50beads currently in use. After three passes, the efficiency increases to 95discussed. Work supported by DARPA/AFOSR Grant No. F49620-02-1-0307, and by the David and Lucile Packard Foundation Grant No. 2001-17715.

Hultgren, A.; Tanase, M.; Felton, E. J.; Meyer, G. J.; Chen, C. S.; Reich, D. H.

2003-03-01

30

Particle acceleration at a reconnecting magnetic separator  

NASA Astrophysics Data System (ADS)

We present first results of test particle orbit calculations in a time-dependent electro-magnetic field configuration which models separator reconnection in three dimensions. The test particle orbits are calculated using the relativistic guiding-centre approximation. The test particles are accelerated to high kinetic energies by the parallel electric field generically associated with three-dimensional magnetic reconnection, with the final energy depending on the choice of model parameters. We will discuss how the test-particle orbits and the energy gain depend on the initial conditions, and how observations (for example, of solar flares) may be used to constrain our model parameters.

Threlfall, James; Neukirch, Thomas; Parnell, Clare; Eradat Oskoui, Solmaz

2014-05-01

31

Selective Separation of Coal Feedstocks for Conversion by Magnetic Separation Techniques.  

National Technical Information Service (NTIS)

The Open-Gradient Magnetic Separation (OGMS) technique can separate particles on the basis of small differences in magnetic susceptibility. The highly reactive coal macerals are diamagnetic while the minerals and less reactive macerals range from slightly...

E. C. Hise A. S. Holman

1981-01-01

32

Magnetic separation techniques in diagnostic microbiology.  

PubMed Central

The principles of magnetic separation aided by antibodies or other specific binding molecules have been used for isolation of specific viable whole organisms, antigens, or nucleic acids. Whereas growth on selective media may be helpful in isolation of a certain bacterial species, immunomagnetic separation (IMS) technology can isolate strains possessing specific and characteristic surface antigens. Further separation, cultivation, and identification of the isolate can be performed by traditional biochemical, immunologic, or molecular methods. PCR can be used for amplification and identification of genes of diagnostic importance for a target organism. The combination of IMS and PCR reduces the assay time to several hours while increasing both specificity and sensitivity. Use of streptavidin-coated magnetic beads for separation of amplified DNA fragments, containing both biotin and a signal molecule, has allowed for the conversion of the traditional PCR into an easy-to-read microtiter plate format. The bead-bound PCR amplicons can also easily be sequenced in an automated DNA sequencer. The latter technique makes it possible to obtain sequence data of 300 to 600 bases from 20 to 30 strains, starting with clinical samples, within 12 to 24 h. Sequence data can be used for both diagnostic and epidemiologic purposes. IMS has been demonstrated to be a useful method in diagnostic microbiology. Most recent publications describe IMS as a method for enhancing the specificity and sensitivity of other detection systems, such as PCR, and providing considerable savings in time compared with traditional diagnostic systems. The relevance to clinical diagnosis has, however, not yet been fully established for all of these new test principles. In the case of PCR, for example, the presence of specific DNA in a food sample does not demonstrate the presence of a live organism capable of inducing a disease. However, all tests offering increased sensitivity and specificity of detection, combined with reduced time of analysis, have to be seriously evaluated. Images

Olsvik, O; Popovic, T; Skjerve, E; Cudjoe, K S; Hornes, E; Ugelstad, J; Uhlen, M

1994-01-01

33

Droplet-based Magnetically Activated Cell Separator (DMACS): Evaluation of separation efficiency versus variance of magnetic flux density  

Microsoft Academic Search

We introduced a droplet-based magnetically activated cell separator (DMACS) that utilizes a hanging droplet of microliter-sized volume for dividing positive (magnetically labeled) and negative (magnetically unlabeled) cells. It enabled us to solve adhesion problem in channel and showed better separation efficiency. However, the separation efficiency was changed under variations of initial volume (the droplet volume of cell suspension before buffer

Youngho Kim; Su Hong; Sang Ho Lee; Kyeongkap Paek; Byungkyu Kim

2006-01-01

34

Selective separation of coal feedstocks for conversion by magnetic separation techniques  

Microsoft Academic Search

The Open-Gradient Magnetic Separation (OGMS) technique can separate particles on the basis of small differences in magnetic susceptibility. The highly reactive coal macerals are diamagnetic while the minerals and less reactive macerals range from slightly diamagnetic to paramagnetic with the pyritic minerals exhibiting the greatest positive magnetic susceptibility. OGMS can spread a falling stream of fine coal into a spectrum

E. C. Hise; A. S. Holman

1981-01-01

35

Railroading cells, microfluidic magnetic cell separation using ferromagnetic stripes  

Microsoft Academic Search

Magnetic cell separation has been demonstrated using recessed ferromagnetic stripes. Here we demonstrate precise control of the cell's positions using branched magnetic stripes in a microfluidic device. The technique allows magnetically separated cells to be delivered in precise locations to downstream cellular analysis components.

David Inglis; Robert Austin; James Sturm

2006-01-01

36

Temperature and magnetic dual responsive microparticles for DNA separation  

Microsoft Academic Search

The use of solid support in DNA separation from biological mixtures for diagnostics offers great potential for developing versatile separating tools. Although different polymer materials have been developed and studied for DNA separation, the application of such non-magnetic particles for DNA separation has remained limited. In this work, we describe the adsorption and desorption behavior of DNA on the temperature

Abdelhamid Elaissari

2011-01-01

37

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

38

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

39

Magnetic separation of FCC equilibrium catalyst by HGMS. [Fluid catalytic cracking (FCC); high gradient magnetic separator (HGMS)  

Microsoft Academic Search

The results of a study on the magnetic separation of a fluid catalytic cracking catalysts by a high gradient magnetic separator are presented. Seven nickel-impregnated catalysts (Ni content ranged from 0.0 to 4.45 wt.%) were mixed in equal amounts as a model sample. The velocity effect of carrier gas is detailed with the magnetic yield and magnetic susceptibility plotted against

S. Takase; M. Ushio; Y. Oishi; T. Morita; T. Shiori

1982-01-01

40

Cryo-negative staining.  

PubMed

A procedure is presented for the preparation of thin layers of vitrified biological suspensions in the presence of ammonium molybdate, which we term cryo-negative staining. The direct blotting of sample plus stain solution on holey carbon supports produces thin aqueous films across the holes, which are routinely thinner than the aqueous film produced by conventional negative staining on a continuous carbon layer. Because of this, a higher than usual concentration of negative stain (ca. 16% rather than 2%) is required for cryo-negative staining in order to produce an optimal image contrast. The maintenance of the hydrated state, the absence of adsorption to a carbon film and associated sample flattening, together with reduced stain granularity, generates high contrast cryo-images of superior quality to conventional air-dry negative staining. Image features characteristic of unstained vitrified cryo-electron microscopic specimens are present, but with reverse contrast. Examples of cryo-negative staining of several particulate biological samples are shown, including bacteriophage T2, tobacco mosaic virus (TMV), bovine liver catalase crystals, tomato bushy stunt virus (TBSV), turnip yellow mosaic virus (TYMV), keyhole limpet hemocyanin (KLH) types 1 and 2, the 20S proteasome from moss and the E. coli chaperone GroEL. Densitometric quantitation of the mass-density of cryo-negatively stained bacteriophage T2 specimens before and after freeze-drying within the TEM indicates a water content of 30% in the vitreous specimen. Determination of the image resolution from cryo-negatively stained TMV rods and catalase crystals shows the presence of optical diffraction data to ca. 10 A and 11.5 A, respectively. For cryo-negatively stained vitrified catalase crystals, electron diffraction shows that atomic resolution is preserved (to better than 20 diffraction orders and less than 3 A). The electron diffraction resolution is reduced to ca. 10 A when catalase crystal specimens are prepared without freezing or when they are freeze-dried in the electron microscope. Thin vitrified films of TMV, TBSV and TYMV in the presence of 16% ammonium molybdate show a clear indication of two-dimensional (2-D) order, confirmed by single particle orientational analysis of TBSV and 2-D crystallographic analysis of TYMV. These observations are in accord with earlier claims that ammonium molybdate induces 2-D array and crystal formation from viruses and macromolecules during drying onto mica. Three-dimensional analysis of the TBSV sample using the tools of icosahedral reconstruction revealed that a significant fraction of the particles were distorted. A reconstruction from a subset of undistorted particles produced the characteristic T = 3 dimer clustered structure of TBSV, although the spikes are shortened relative to the structure defined by X-ray crystallography. The 20S proteasome, GroEL, catalase, bacteriophage T2, TMV, TBSV and TYMV all show no indication of sample instability during cryo-negative staining. However, detectable dissociation of the KLH2 oligomers in the presence of the high concentration of ammonium molybdate conforms with existing knowledge on the molybdate-induced dissociation of this molecule. This indicates that the possibility of sample-stain interaction in solution, prior to vitrification, must always be carefully assessed. PMID:9684350

Adrian, M; Dubochet, J; Fuller, S D; Harris, J R

1998-01-01

41

A Continuous Throughput Micro Magnetic Cell Separator  

Microsoft Academic Search

Micro-fluidic total analysis systems for diagnosis, research and treatment require foolproof sorting and separation techniques. A bulk fluid sample invariably contains unwanted and useless matter that must be disposed of. The chip must first be able to separate the wheat from the chaff before doing any analysis. A micro-fluidic device that continuously separates blood cells from a whole blood sample

David Inglis; James C. Sturm; Robert H. Austin

2004-01-01

42

Magnetic separation of coal fly ash from Bulgarian power plants.  

PubMed

Fly ash from three coal-burning power plants in Bulgaria: 'Maritza 3', 'Republika' and 'Rousse East' were subjected to wet low-intensity magnetic separation. The tests were performed at different combinations of magnetic field intensity, flow velocity and diameter of matrix elements. It was found that all parameters investigated affected the separation efficiency, but their influence was interlinked and was determined by the properties of the material and the combination of other conditions. Among the fly ash characteristics, the most important parameters, determining the magnetic separation applicability, were mineralogical composition and distribution of minerals in particles. The main factors limiting the process were the presence of paramagnetic Fe-containing mineral and amorphous matter, and the existence of poly-mineral particles and aggregates of magnetic and non-magnetic particles. It was demonstrated that the negative effect of both factors could be considerably limited by the selection of a proper set of separation conditions. The dependences between concentration of ferromagnetic iron in the ash, their magnetic properties and magnetic fraction yields were studied. It was experimentally proved that, for a certain set of separation conditions, the yields of magnetic fractions were directly proportional to the saturation magnetization of the ferromagnetic components of the ash. The main properties of typical magnetic and non-magnetic fractions were studied. PMID:20699291

Shoumkova, Annie S

2011-10-01

43

Continuous cell separation using novel magnetic quadrupole flow sorter  

Microsoft Academic Search

A laboratory prototype of a flow cell sorter based on magnetic quadrupole field was built and evaluated. The magnetic force acting on magnetically labeled cells in such a field has a `centrifugal’ character which provides a basis for the design of a continuous separation process. The sorter was tested on a model cell system of human peripheral lymphocytes labeled with

Maciej Zborowski; Liping Sun; Lee R Moore; P Stephen Williams; Jeffrey J. Chalmers

1999-01-01

44

Magnetic separator having a multilayer matrix, method and apparatus  

DOEpatents

A magnetic separator having multiple staggered layers of porous magnetic material positioned to intercept a fluid stream carrying magnetic particles and so placed that a bypass of each layer is effected as the pores of the layer become filled with material extracted from the fluid stream.

Kelland, David R. (Lexington, MA)

1980-01-01

45

Density separation of solids in ferrofluids with magnetic grids  

SciTech Connect

Nonmagnetic solids in a superparamagnetic ferrofluid are subjected to body forces proportional to the intensity of magnetization of the fluid and the gradient of the magnetic field. An apparent density of the fluid can be defined from the force equations, and since the apparent density can be much larger than the true density, it is possible to levitate or float dense objects. Mixtures of solids with a density greater than the apparent density sink while lower density solids float. In practice it is difficult to create a uniform gradient over a large volume and single gap magnetic separators require very large magnets or have a limited throughput. To overcome that problem, multiple gap magnetic grids have been designed. Such grids consist of planar arrays of parallel bars of alternating polarity, driven by permanent magnets. When immersed in ferrofluid, magnetic grids create nonuniform field gradients and apparent densities in the fluid. However, both analysis and experimental measurements show that the grid acts as a barrier to particles below a critical density, while permitting more dense particles to fall through the grid. Thus, a magnetic grid filter can be used as a high throughput binary separator of solids according to their densities. Such filters can be cascaded for more complex separations. Several magnetic grid filters have been designed, built, and tested. Magnetic measurements qualitatively agree with the theoretical predictions. Experiments with synthetic mixtures have demonstrated that good binary separations can be made.

Fay, H. (Union Carbide Corp., Tonawanda, NY); Quets, J.M.

1980-04-01

46

Microstripes for transport and separation of magnetic particles.  

PubMed

We present a simple technique for creating an on-chip magnetic particle conveyor based on exchange-biased permalloy microstripes. The particle transportation relies on an array of stripes with a spacing smaller than their width in conjunction with a periodic sequence of four different externally applied magnetic fields. We demonstrate the controlled transportation of a large population of particles over several millimeters of distance as well as the spatial separation of two populations of magnetic particles with different magnetophoretic mobilities. The technique can be used for the controlled selective manipulation and separation of magnetically labelled species. PMID:22655020

Donolato, Marco; Dalslet, Bjarke Thomas; Hansen, Mikkel Fougt

2012-06-01

47

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

48

Development of micro immuno-magnetic cell sorting system with lamination mixer and magnetic separator  

Microsoft Academic Search

A novel micro immuno-magnetic cell sorting system has been developed for rare cell extraction. The present system consists of a lamination mixer for labeling target cells with magnetic beads, and a separator with an embedded coil, where continuous cell separation is accomplished. We have fabricated a prototype system using soft lithography, and evaluated the separation performance. We successfully achieved the

Hiromichi Inokuchi; Yuji Suzuki; Nobuhide Kasagi

49

A Novel Magnetic Separation Technique: Selective Separation of Ultrafine Particles by Magnetophoresis  

Microsoft Academic Search

The selective and specific extraction of species of interest from local environmental and other sample sources are important for scientific research, industrial processes, and environmental applications. A novel process for selective separation of magnetic particles using magnetophoresis is investigated. The principle of this process is that the direction and velocity of particle movement in a magnetic field gradient are determined

F. Coyne Prenger; Laura A. Worl; Michael D. Johnson; Joseph A. Waynert; Robert M. Wingo

2004-01-01

50

Physicochemical properties of magnetically separated shale oil solids  

Microsoft Academic Search

The authors present thermomagnetic and X-ray studies to show that the composition of shale oil solids magnetically separated from three different shale oil feeds are distinctly varied, but that high ash removal efficiencies are, nonetheless, obtainable under appropriate conditions for all three shale oils investigated. On the basis of the magnetic behavior exhibited by the shale oil solids, a qualitative

K. M. Jeong; L. Petrakis; M. Takayasu; F. J. Friedlaender

1984-01-01

51

MAGNETITE RECOVERY IN COAL WASHING BY HIGH GRADIENT MAGNETIC SEPARATION  

EPA Science Inventory

The report describes a demonstration of the successful recovery of magnetite from mixtures of magnetite and coal, like those found in a coal-washing circuit, by High Gradient Magnetic Separation. The demonstration was part of a research program at Francis Bitter National Magnet L...

52

Novel platform for minimizing cell loss on separation process: Droplet-based magnetically activated cell separator  

Microsoft Academic Search

To reduce the problem of cell loss due to adhesion, one of the basic phenomena in microchannel, we proposed the droplet-based magnetically activated cell separator (DMACS). Based on the platform of the DMACS-which consists of permanent magnets, a coverslip with a circle-shaped boundary, and an injection tube-we could collect magnetically (CD45)-labeled (positive) cells with high purity and minimize cell loss

Youngho Kim; Su Hong; Sang Ho Lee; Kangsun Lee; Seok Yun; Yuri Kang; Kyeong-Kap Paek; Byeong-Kwon Ju; Byungkyu Kim

2007-01-01

53

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

54

Rare cell separation and analysis by magnetic sorting.  

PubMed

The separation and or isolation of rare cells using magnetic forces are commonly used and growing in use ranging from simple sample prep for further studies to a FDA approved, clinical diagnostic test. This growth is the result of both the demand to obtain homogeneous rare cells for molecular analysis and the dramatic increases in the power of permanent magnets that even allow the separation of some unlabeled cells based on intrinsic magnetic moments, such as malaria parasite-infected red blood cells. PMID:21812408

Zborowski, Maciej; Chalmers, Jeffrey J

2011-11-01

55

Separation system and efficient capture of contaminants using magnetic nanoparticles  

US Patent & Trademark Office Database

Methods are disclosed for the capture, detection, separation, isolation and quantification of contaminants in a starting material. Also disclosed are competitive assay methods for the detection and quantification of contaminants in a starting material. Kits for use with the method are disclosed as well. A system for capturing, separating and/or concentrating contaminants from a material is also presented. The system captures, separates and/or concentrates contaminants such as bacteria, viruses, other microorganisms, and/or larger items, such as insects, from a variety of materials, such as food, and environmental and clinical materials. In general, the system uses a rotating magnetic field to mix the material with magnetic particles to capture the target contaminants, and a fixed magnetic field to separate and concentrate the captured target contaminants.

2010-04-20

56

Separating Magnetically Labeled and Unlabeled Biological Cells within Microfluidic Channels  

NASA Astrophysics Data System (ADS)

The transport of microscopic objects that rely on magnetic forces have numerous advantages including flexibility of controlling many design parameters and the long range magnetic interactions generally do not adversely affect biological or chemical interactions. We present results on the use of magnetic micro-arrays imprinted within polydimethylsiloxane (PDMS) microfluidic channels that benefit from these features and the ability to rapidly reprogram the magnetic energy landscape for cell manipulation and sorting applications. A central enabling feature is the very large, tunable, magnetic field gradients (> 10^4 T/m) that can be designed within the microfluidic architecture. Through use of antibody-conjugated magnetic microspheres to label biological cells, results on the transport and sorting of heterogeneous cell populations are presented. The effects of micro-array and fluid channel design parameters, competition between magnetic forces and hydrodynamic drag forces, and cell-labeling efficiency on cell separation are discussed.

Byvank, Tom; Vieira, Greg; Miller, Brandon; Yu, Bo; Chalmers, Jeffrey; Lee, L. James; Sooryakumar, R.

2011-03-01

57

Differential magnetic catch and release: analysis and separation of magnetic nanoparticles.  

PubMed

This article reports the purification and separation of magnetic nanoparticle mixtures using differential magnetic catch and release (DMCR). This method applies a variable magnetic flux orthogonal to the flow direction in an open tubular capillary to trap and controllably release magnetic nanoparticles. Magnetic moments of 8, 12, and 17 nm diameter CoFe2O4 nanoparticles are calculated using the applied magnetic flux and experimentally determined force required to trap 50% of the particle sample. Balancing the relative strengths of the drag and magnetic forces enables separation and purification of magnetic CoFe2O4 nanoparticle samples with <20 nm diameters. Samples were characterized by transmission electron microscopy to determine the average size and size dispersity of the sample population. DMCR is further demonstrated to be useful for separation of a magnetic nanoparticle mixture, resulting in samples with narrowed size distributions. PMID:19891452

Beveridge, Jacob S; Stephens, Jason R; Latham, Andrew H; Williams, Mary Elizabeth

2009-12-01

58

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

59

Process to remove actinides from soil using magnetic separation  

DOEpatents

A process of separating actinide-containing components from an admixture including forming a slurry including actinide-containing components within an admixture, said slurry including a dispersion-promoting surfactant, adjusting the pH of the slurry to within a desired range, and, passing said slurry through a pretreated matrix material, said matrix material adapted to generate high magnetic field gradients upon the application of a strong magnetic field exceeding about 0.1 Tesla whereupon a portion of said actinide-containing components are separated from said slurry and remain adhered upon said matrix material is provided.

Avens, Larry R. (Los Alamos, NM); Hill, Dallas D. (Los Alamos, NM); Prenger, F. Coyne (Los Alamos, NM); Stewart, Walter F. (Las Cruces, NM); Tolt, Thomas L. (Los Alamos, NM); Worl, Laura A. (Los Alamos, NM)

1996-01-01

60

Silica coated magnetic nanoparticles for separation of nuclear acidic waste  

NASA Astrophysics Data System (ADS)

Fe2O3 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 Fe2O3 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.; Johnson, A.; Kaczor, J.; Kaur, M.; Paszczynski, A.; Qiang, Y.

2010-05-01

61

Assessment of Alphamagnetic Spectrometer (AMS) Upper Experiment Structural Configuration Shielding Effectiveness Associated with Change from Cryo-Cooled Magnet to Permanent Magnet  

NASA Technical Reports Server (NTRS)

In the spring of 2010, the Alpha Magnetic Spectrometer 2 (AMS-02) underwent a series of system level electromagnetic interference control measurements, followed by thermal vacuum testing. Shortly after completion of the thermal vacuum testing, the project decided to remove the cryogenically cooled superconducting magnet, and replace it with the original permanent magnet design employed in the earlier AMS- 01 assembly. Doing so necessitated several structural changes, as well as removal or modification of numerous electronic and thermal control devices and systems. At this stage, the project was rapidly approaching key milestone dates for hardware completion and delivery for launch, and had little time for additional testing or assessment of any impact to the electromagnetic signature of the AMS-02. Therefore, an analytical assessment of the radiated emissions behavioural changes associated with the system changes was requested.

Scully, Robert

2012-01-01

62

Development of chitosan-conjugated magnetite for magnetic cell separation  

Microsoft Academic Search

For the purpose of separating microorganisms from culture broth by magnetic force, magnetic particles were conjugated with a polymer to produce polymer-conjugated magnetite (polymer-mag). Among 4 preparation methods investigated—aminosilane coupling, glycidylsilane coupling, crosslinking, and co-precipitation—, polymer-mag prepared by co-precipitation showed the highest cell recovery and high dispersibility. When various cationic, anionic, and nonionic polymers were used to prepare polymer-mag and

Hiroyuki Honda; Atsushi Kawabe; Masashige Shinkai; Takeshi Kobayashi

1998-01-01

63

Advantage of combining magnetic cell separation with sperm preparation techniques  

Microsoft Academic Search

The selection of vital, non-apoptotic spermatozoa is a prerequisite for achieving optimal conception rates in assisted reproductive techniques. Magnetic cell sorting using annexin-V microbeads can effectively separate apoptotic and non-apoptotic spermatozoa. The objective of the present study was to optimize the integration of magnetic cell sorting in standard sperm preparations and to correlate the effect of different sperm preparation procedures

Tamer M Said; Sonja Grunewald; Uwe Paasch; Hans-Juergen Glander; Thomas Baumann; Christian Kriegel; Liang Li; Ashok Agarwal

2005-01-01

64

CHAOTIC MIXING OF MAGNETIC BEADS IN MICRO CELL SEPARATOR  

Microsoft Academic Search

ABSTRACT In micro-scale biological assay systems, the mixing of bio- molecules,becomes ,a critical ,issue because ,of their ,small diffusivity. Chaotic features in a novel micro-mixer designed for cell separation system based on magnetic beads (Suzuki and Ho, 2002) is investigated in detail by means of numerical simu- lation. The mechanism,and the optimum,condition to lead the motion of magnetic beads to

Hiroaki Suzuki; Nobuhide Kasagi; Chih-ming Ho

65

Separation of feeble magnetic particles with magneto-Archimedes levitation  

Microsoft Academic Search

Particles and solid substances with feeble magnetic susceptibility were levitated by magnetic fields with the aid of the “magneto-Archimedes levitation” method [Nature 393 (1998) 749]. A novel feature was found, namely that the initial particle mixture levitated underwent separation into each kind of the ingredient particle aggregates. The samples levitated were NaCl–KCl grain mixtures, and colored glass particles. The experiments

Y Ikezoe; T Kaihatsu; S Sakae; H Uetake; N Hirota; K Kitazawa

2002-01-01

66

Magnetic field analysis of high gradient magnetic separator via finite element analysis  

NASA Astrophysics Data System (ADS)

High Gradient Magnetic Separator (HGMS) uses matrix to make high magnetic field gradient so that ferro- or para-magnetic particles can be attracted to them by high magnetic force. The magnetic force generated by the field gradient is several thousand times larger than that by the magnetic flux density alone. So the HGMS shows excellent performance compared with other magnetic separators. These matrices are usually composed of stainless wires having high magnetization characteristics. This paper deals with superconducting HGMS which is aimed for purifying wastewater by using stainless steel matrix. Background magnetic field up to 6 T is generated by a superconducting solenoid and the stainless steel matrices are arranged inside of the solenoid. In order to calculate magnetic forces exerting on magnetic particles in wastewater, it is important to calculate magnetic field and magnetic field gradient those are proportional to the magnetic force acting on the particle. So we presents magnetic field distribution analysis result and estimates how many times of magnetic force will act on a particle when the matrix are arranged or not. Magnetic field is calculated in 3 dimensions by using Finite Element Method (FEM) and also compared with results obtained from 2 dimensional analysis.

Baik, S. K.; Ha, D. W.; Ko, R. K.; Kwon, J. M.

2012-10-01

67

Magnetic Separation of Mineral Matter from Coal Liquids. Final Report.  

National Technical Information Service (NTIS)

The earlier study of the magnetic separation of mineral matter from coal liquids reported in EPRI Report AF-508 has been carried forward with significant improvements in the technique and results. Treatment of the dry residual filter-feed solids with appr...

E. Maxwell D. R. Kelland I. S. Jacobs L. M. Levinson

1978-01-01

68

D0 Cryo System ODH and Cryo Alarm System Response  

SciTech Connect

The D0 Cryo System is monitored by a computerized process control system and an ODH safety system. During steady state operations the cryo system will be unmanned and system experts will depend on communication systems for notification of system problems. The FIRUS system meets the minimum communication requirement and is supplemented with an autodialer which attempts to contact cryo operators by pager or phone. The RD/Safety Department requires the ODH monitor system to be connected to the labwide FIRUS system. which enables the Communications Center to receive alarms and notify the proper experts of the condition. The ODH system will have two alarm points. One for an ODH alarm and one for a system trouble alarm. The autodialer system has replaced a former cryo operations summation alarm point in the FIRUS system. This has freed space on the FIRUS system and has allowed the cryo experts more flexibility in setting up their own communication link. The FIRUS and the autodialer systems receive alarms and access lists of experts to call for notification of problems. Attempts to contact these experts will continue until the alarm or alarms is acknowledged.

Urbin, J.; Dixon, K.; /Fermilab

1990-04-05

69

Physicochemical properties of magnetically separated shale oil solids  

SciTech Connect

The authors present thermomagnetic and X-ray studies to show that the composition of shale oil solids magnetically separated from three different shale oil feeds are distinctly varied, but that high ash removal efficiencies are, nonetheless, obtainable under appropriate conditions for all three shale oils investigated. On the basis of the magnetic behavior exhibited by the shale oil solids, a qualitative measure of the different phase transformations and the species present is obtained. These data reflect the general occurrence of a paramagnetic phase mixed with a trace amount of a ferromagnetic component. This conclusion is consistent with the bulk mineralogy and elemental composition results for the shale magnetic separation system and the choice of operating parameters.

Jeong, K.M.; Petrakis, L.; Takayasu, M.; Friedlaender, F.J.

1984-01-01

70

New design for a space cryo-mechanism  

NASA Astrophysics Data System (ADS)

Based on its experience of space application instrument and its development of cryomechanism for astronomical ground based instrument VLT / VISIR, CEA Saclay is proposing a new concept of Space Cryomechanism. This design is based on VLT/VISIR cryo-mechanism design adapted to space requirements taking into account all the specification of space environment (vibrations at launch, cryogenic vacuum, materials, radiations, ...). The original concept of the design is based on the association of the key elements: a dog-clutch with Hirth teeth jaws coupled to a step-by-step space qualified cryo-motor, a bellows that allows for separation of indexing and rotating functions, and enlarged bearings design in "O" arrangement that increase robustness to vibration. The actuator has 360 steady positions that can be reached within les than a second with repeatability of 5 arcsec peak to peak. After a presentation of the details of the concept and of its benefits to robustness to space environment, the paper describes the thoroughly qualification program of the cryo-mechanism with respect to space requirements (cryo-cycling, indexing accuracy, power consumption, heat dissipation, motorisation margins, vibrations). This cryo-mechanism may be built in 3 different sizes for wheels up to 10 kg.

Durand, Gilles; Amiaux, Jérôme; Augueres, Jean-Louis; Carty, Michael; Barrière, Jean Christophe; Bouzat, Marylène; Duboué, Bruno; Lagage, Pierre Olivier; Lebeuf, Didier; Lepage, Erwan; Lemer, Isabelle; Marlaguey, Nathalie Peydrol; Poupar, Sébastien

2008-07-01

71

CryoTran user's manual, version 1.0  

NASA Technical Reports Server (NTRS)

The development of cryogenic fluid management systems for space operation is a major portion of the efforts of the Cryogenic Fluids Technology Office (CFTO) at the NASA Lewis Research Center. Analytical models are a necessary part of experimental programs which are used to verify the results of experiments and are also used as a predictor for parametric studies. The CryoTran computer program is a bridge to obtain analytical results. The object of CryoTran is to coordinate these separate analyses into an integrated framework with a user-friendly interface and a common cryogenic property database. CryoTran is an integrated software system designed to help solve a diverse set of problems involving cryogenic fluid storage and transfer in both ground and low-g environments.

Cowgill, Glenn R.; Chato, David J.; Saad, Ehab

1989-01-01

72

Upgrading mixed polyolefin waste with magnetic density separation.  

PubMed

Polyolefin fractions are often end fractions resulting from the recycling of end-of-life consumer products. Polypropylene (PP) and polyethylene (PE) are present in such fractions as a mixture. For instance, the ratio of PP and PE in car scrap is 70:30 on average. However, the grade of the PP and PE should typically be better than 97% to be reused again as a high quality product. Density separation of the different polyolefins can be a solution. A promising separation technique is the inverse magnetic density separator (IMDS). This paper discusses the potential of shredder residue, one of the possible polyolefin's waste stream sources for the IMDS, in detail. Experiments with the separation of polyolefins with an IMDS prototype show both high grade and high recovery. The paper concludes with the economic opportunities of the IMDS in the recycling of polyolefins. PMID:19128952

Bakker, E J; Rem, P C; Fraunholcz, N

2009-05-01

73

Experimental investigation of magnetically actuated separation using tangential microfluidic channels and magnetic nanoparticles.  

PubMed

A novel continuous switching/separation scheme of magnetic nanoparticles (MNPs) in a sub-microlitre fluid volume surrounded by neodymium permanent magnet is studied in this work using tangential microfluidic channels. Polydimethylsiloxane tangential microchannels are fabricated using a novel micromoulding technique that can be done without a clean room and at much lower cost and time. Negligible switching of MNPs is seen in the absence of magnetic field, whereas 90% of switching is observed in the presence of magnetic field. The flow rate of MNPs solution had dramatic impact on separation performance. An optimum value of the flow rate is found that resulted in providing effective MNP separation at much faster rate. Separation performance is also investigated for a mixture containing non-magnetic polystyrene particles and MNPs. It is found that MNPs preferentially moved from lower microchannel to upper microchannel resulting in efficient separation. The proof-of-concept experiments performed in this work demonstrates that microfluidic bioseparation can be efficiently achieved using functionalised MNPs, together with tangential microchannels, appropriate magnetic field strength and optimum flow rates. This work verifies that a simple low-cost magnetic switching scheme can be potentially of great utility for the separation and detection of biomolecules in microfluidic lab-on-a-chip systems. PMID:25014081

Munir, Ahsan; Zhu, Zanzan; Wang, Jianlong; Zhou, Hong Susan

2014-06-01

74

A Zernike-moment-based non-local denoising filter for cryo-EM images.  

PubMed

Cryo-electron microscopy (cryo-EM) plays an important role in determining the structure of proteins, viruses, and even the whole cell. It can capture dynamic structural changes of large protein complexes, which other methods such as X-ray crystallography and nuclear magnetic resonance analysis find difficult. The signal-to-noise ratio of cryo-EM images is low and the contrast is very weak, and therefore, the images are very noisy and require filtering. In this paper, a filtering method based on non-local means and Zernike moments is proposed. The method takes into account the rotational symmetry of some biological molecules to enhance the signal-to-noise ratio of cryo-EM images. The method may be useful in cryo-EM image processing such as the automatic selection of particles, orientation determination, and the building of initial models. PMID:23564187

Wang, Jia; Yin, Changcheng

2013-04-01

75

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

76

A separation property for magnetic Schrödinger operators on Riemannian manifolds  

NASA Astrophysics Data System (ADS)

We consider a Schrödinger differential expression L=?A+q on a complete Riemannian manifold (M,g) with metric g, where ?A is the magnetic Laplacian on M and q?0 is a locally square integrable function on M. In the terminology of W.N. Everitt and M. Giertz, the differential expression L is said to be separated in L2(M) if for all u?L2(M) such that Lu?L2(M), we have qu?L2(M). We give sufficient conditions for L to be separated in L2(M).

Milatovic, Ognjen

2011-01-01

77

Capture of metallic copper by high gradient magnetic separation system.  

PubMed

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 with a permalloy matrix net under a high gradient magnetic field. The captured solids were predominantly 6-20 microm in diameter, with Cu2O and CuO present among the solids. Four treatment configurations with and without the use of magnetic field and metal alloy as the matrix net were tested and their effects evaluated: (1) no magnetic field or matrix, (2) no magnetic field but with matrix, (3) with magnetic field but no matrix, (4) with both magnetic field and matrix. At flow rates of 40, 60, 80 and 100 cm3/min, capture efficiencies for metallic copper in the absence of magnetic field were 87%, 86%, 63%, and 39%, respectively, and in the presence of magnetic field were 99%, 98%, 95%, and 93%, respectively. The HGMS was critical for a high capture efficiency, whereas a matrix net only marginally enhanced it. Additional tests with a larger reactor confirmed similarly high efficiencies of > 85%. The use of an alloy matrix appeared to be important when high flow rates are most likely to be employed in practical applications. PMID:22329132

Wu, Wan-I; Wu, Chung-Hsin; Hong, P K Andy; Lin, Cheng-Fang

2011-10-01

78

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

79

Cell separation in a microfluidic channel using magnetic microspheres  

Microsoft Academic Search

Magnetophoretic isolation of biological cells in a microfluidic environment has strong relevance in biomedicine and biotechnology.\\u000a A numerical analysis of magnetophoretic cell separation using magnetic microspheres in a straight and a T-shaped microfluidic\\u000a channel under the influence of a line dipole is presented. The effect of coupled particle–fluid interactions on the fluid\\u000a flow and particle trajectories are investigated under different

Nipu Modak; Amitava Datta; Ranjan Ganguly

2009-01-01

80

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

81

Radiolysis and hydrolysis of magnetically assisted chemical separation particles  

SciTech Connect

The magnetically assisted chemical separation process is designed to separate transuranic (TRU) elements from high-level waste or TRU waste. Magnetic micro-particles (1-25 {mu}m) were coated from octyl (phenyl)-N,N-diisobutylcarbamoyl-methylphosphine oxide dissolved in tributyl phosphate and tested for removing TRU elements from acidic nitrate solutions. The particles were contacted with nitric acid solutions or simulated Hanford Plutonium Finishing Plant waste solution, irradiated with a high intensity {sup 60}Co {gamma}-ray source, and evaluated for their effectiveness in removing TRU elements from 2 M 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, magnetic susceptibility measurements, and physical observations of the particles. Processes that affect the surface of the particles were found to 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. [Argonne National Lab., IL (United States)

1996-08-01

82

A microfabricated planar magnetic particle separator with optically inspectable flow channel  

Microsoft Academic Search

A new planar magnetic particle separator with opening flow channel which can separate magnetic beads from suspended bio-fluids has been realized on silicon and Pyrex glass wafers, using microfabrication techniques. Electromagnets and fluid channels are separately fabricated, and then two components are bonded together to construct the separator using electrostatic wafer bonding techniques. Separation tests are performed by flowing a

Wenjin Zhang; C. H. Ahn

1996-01-01

83

The Yale Gas-Filled Split Pole Magnetic Separator  

NASA Astrophysics Data System (ADS)

Design and construction of a gas-filled recoil separator is underway at the Wright Nuclear Structure Laboratory at Yale University. By filling the magnetic field region of the existing Enge Split-Pole magnet with N2 or He2 gases in the 1 to 15 mbar pressure range a gradual focussing of discrete charge states has been measured. The incident ions were ^16O and ^35,37Cl with 49 MeV and 95 MeV energies, respectively. The process is understood as a result of coalescing of trajectories of different charge states around a trajectory defined by the mean charge state (q¯) of the ion in gas. Because q¯ depends on the atomic number Z and is roughly proportional with the ion velocity, the average magnetic rigidity (B¯?=Av/q¯) is almost independent of the velocity distribution of the incident ions. The ion trajectories will be therefore be mainly determined by the mass number A and the atomic number Z of the ion. Monte Carlo simulations with the code RAYTRACE closely reproduce the experimental behavior. We plan to use the Yale Mass Separator (YaMS) for nuclear structure studies in conjunction with high efficency gamma detectors (clover detectors) for enhancing weak reaction channels and fission background reduction. Work supported by the US-DOE under contract numbers DE-FG02-91ER-40609 and DE-FG02-88ER-40417.

Cata-Danil, G.; Beausang, C. W.; Casten, R. F.; Chen, A.; Chubrich, N.; Cooper, J. R.; Krücken, R.; Liu, B.; Novak, J. R.; Visser, D.; Zamfir, N. V.

1998-10-01

84

Photocatalytically active titanium dioxide nanopowders: Synthesis, photoactivity and magnetic separation  

NASA Astrophysics Data System (ADS)

Two approaches were used to obtain nanocrystalline titanium dioxide (TiO2) photocatalyst powders. Firstly, low-temperature synthesis method and secondly liquid flame spraying. The structural properties of the produced powders were determined with X-ray diffraction, transmission electron microscopy and nitrogen adsorption tests. The photocatalytic properties of the powders were studied with methylene blue (MB) discoloration tests. After discolorations tests, TiO2 was coagulated with magnetite particles using FeCl3·6 H2O at a fixed pH value. Magnetic separation of coagulated TiO2 and magnetite was carried out by a permanent magnet. The obtained results showed that the particle size of the powders synthesized at low-temperature was very small and the specific surface area high. The phase content of the powder was also shown to depend greatly on the acidity of the synthesis solution. Powder synthesized by liquid flame spraying was mixture of anatase and rutile phases with essentially larger particle size and lower specific surface area than those of low-temperature synthesized powders. The MB discoloration test showed that photocatalytic activity depends on the phase structure as well as the specific surface area of the synthesized TiO2 powder. The magnetic separation of TiO2-magnetite coagulate from solution proved to be efficient around pH:8.

Nikkanen, J.-P.; Heinonen, S.; Huttunen Saarivirta, E.; Honkanen, M.; Levänen, E.

2013-12-01

85

Rapid microfluidic separation of magnetic beads through dielectrophoresis and magnetophoresis.  

PubMed

We present the design and fabrication of a new microfluidic device in which the dielectrophoresis and magnetophoresis phenomena were used for the separation of the superparamagnetic microbeads of different sizes. By exploiting the fact that two different particles can exhibit different dielectrophoretic force-frequency spectra, we utilize this device to perform multiplex detection from a single sample solution. We found the transition frequency range for 1, 2.8, and 4.5 microm magnetic beads using our device. Bead-based analysis revealed that a high separation efficiency ( approximately 90%) could be obtained from a single sample solution containing both 4.5 and 2.8 microm beads. The average flow velocity of the beads was maintained at 9.8 mm/s, enabling fast analysis with a smaller amount of reagents. The magnetic field distribution on the beads and the bead flow at the channel cross section for different dielectrophoretic conditions was obtained using CFD-ACE(+) simulation. Issues relating to the fabrication and operation of the device are discussed in detail. Finally, we demonstrated the feasibility of parallel detection/trapping of different beads on the same chip. This separation approach offers the performance of multiplex analysis in lab-on-a-chip devices. PMID:19425001

Krishnan, Jegatha Nambi; Kim, Choong; Park, Hyun Jik; Kang, Ji Yoon; Kim, Tae Song; Kim, Sang Kyung

2009-05-01

86

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

Microsoft Academic Search

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 6T. The magnetic field distribution

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

2011-01-01

87

Apparatus for magnetic separation of paramagnetic and diamagnetic material  

US Patent & Trademark Office Database

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 quadropole 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.

1988-10-18

88

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 quadropole 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.

Doctor, Richard D. (Glen Ellyn, IL)

1988-01-01

89

Continuous separation of dry crushed coal at one ton per hour by high-gradient magnetic separation  

NASA Astrophysics Data System (ADS)

The separation of pyritic sulfur and ash forming minerals from dry crushed coal in a small, cyclic, high gradient magnetic separator over a range of each of the process parameters was tested. A band of operating conditions that affected reductions of the mineral contaminants and recoveries of the heating value comparable to gravimetric separations was defined. The procedures and results of an experimental program to extrapolate from the small, cyclic separations to continuous, pilot scale separation at a feed rate of 1 ton/h are described. The program testing magnetic preparation of dry crushed coal has demonstrated that: (1) dry crushed coal in the size range of about 600 x 45 microns can be effectively cleaned by magnetic separation techniques; (2) product quality and heating value recovery by the high gradient magnetic process approaches that obtained by a laboratory gravimetric separation of the same size fraction; and (3) separations performed on size fractions from 600 to 45 microns at a feed rate of 1 ton/h in a continuous, industrial type high gradient magnetic separator equal those obtained in a cyclic laboratory separator.

Hise, E. C.; Wechsler, I.; Doulin, J. M.

1981-12-01

90

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

91

Titania deposited on soft magnetic activated carbon as a magnetically separable photocatalyst with enhanced activity  

NASA Astrophysics Data System (ADS)

Magnetically separable composite photocatalysts, TiO 2 deposited on soft magnetic ferrite activated carbon (TFAC), were prepared by sol-gel and dip-coating technique. The prepared composites were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), Fourier transform infrared spectra (FTIR), optical absorption spectroscopy, vibrating sample magnetometer (VSM) and nitrogen adsorption. These photocatalysts exhibited enhanced photocatalytic activity compared to Degussa P25 for the degradation of methyl orange (MO) in aqueous solution. The kinetics of MO degradation was well fitted to the Langmuir-Hinshelwood model. The samples showed good magnetic response and could be completely recovered by an external magnet. Furthermore, the photocatalysts could maintain high photocatalytic activity after five cycles, and the degradation rate of MO was still close to 90%.

Wang, Shaohua; Zhou, Shaoqi

2010-08-01

92

ACSD labelling and magnetic cell separation: a rapid method of separating antibody secreting cells from non-secreting cells  

Microsoft Academic Search

Several new ways of selecting cells have recently been developed. These include magnetic separation of cells by labelling with magnetic beads against the recombinant product, gel microdrop technology which encapsulates the cells in gelatine beads and matrix-based secretion assays. Affinity capture surface display (ACSD) is a matrix-based assay for the enrichment of high producing cells and relies on the strong

Silvia Carroll; Mohamed Al-Rubeai

2005-01-01

93

Continuous Separation of Dry Crushed Coal at One Ton Per Hour by High-Gradient Magnetic Separation.  

National Technical Information Service (NTIS)

An earlier experimental program tested the separation of pyritic sulfur and ash-forming minerals from dry crushed coal in a small, cyclic, high-gradient magnetic separator over a range of each of the process parameters. That experimental program defined a...

E. C. Hise I. Wechsler J. M. Doulin

1981-01-01

94

Mercury removal from solution by superconducting magnetic separation with nanostructured magnetic adsorbents  

NASA Astrophysics Data System (ADS)

Recently, mercury Hg concentration in human blood increases due to expanding the global mercury contamination. Excess mercury bioaccumulation poses a significant health risk. In order to decrease mercury concentration in the environment and human blood, we have developed two different kinds of nanostructured magnetic adsorbents for mercury to apply them to superconducting magnetic separation instead of conventional filtration. One is magnetic beads (MBs) which have nanosize magnetite particles in the core and a lot of SH radicals on the surface to adsorb Hg ions effectively. MBs were developed mainly to remove mercury from human blood. The maximum amount of the adsorption for MBs is 6.3 mg/g in the solution in less than a minute. Dithiothreitol can easily remove mercury adsorbed to MBs, hence MBs can be reusable. The other is nanostructured magnetic activated carbon (MAC) which is activated carbon with mesopores and nanosize magnetite. The maximum amount of the adsorption for MAC is 38.3 mg/g in the solution. By heat-treatment mercury can be easily removed from MAC. We have studied superconducting magnetic separation using each adsorbent for mercury removal from solution.

Okamoto, T.; Tachibana, S.; Miura, O.; Takeuchi, M.

2011-11-01

95

CryoSat-2 and the CryoSat Mission  

NASA Astrophysics Data System (ADS)

CryoSat was chosen as the first of ESA's Earth Explorer Opportunity missions in late 1999, following a competitive selection process. Its goal is the measurement of secular change in the cryosphere, particularly in the elevation of the ice caps and the thickness of sea ice. The required accuracy corresponds to about half of the variation expected due to natural variability, over reasonable scales for the surfaces concerned. The selected technique is radar altimetry, although the instrument has been modified to provide the enhanced capabilities needed to significantly extend the spatial coverage of previous altimetry missions, particularly ERS and EnviSat. Thus the radar includes a synthetic aperture mode which enables the along- track resolution to be improved to about 250 m. This will enable detection of leads in sea-ice which are narrower than those detected hitherto, so that operation deeper into pack-ice can be achieved with a consequent reduction in errors due to omission. Altimetry over the steep edges of ice caps is hampered by the irregular topography which, since the radar ranging is performed to the closest reflector rather than the point directly below, introduces uncertainty into the exactitude of repeat measurements. CryoSat's radar includes a second antenna and receiver chain so that interferometry may be used to determine the arrival angle of the echo and so improve localisation of the reflection. The satellite payload, which includes a DORIS receiver for precise orbit determination and a set of star trackers to measure the orientation of the interferometer, is quite complex and demanding. The satellite was launched on 8 October 2005, just less than 6 years after the start of the programme. Unfortunately the launch vehicle, a Rockot launcher derived from the Russian SS-19 ICBM, suffered an anomaly at the end of its second-stage flight, with the result that the satellite was lost, the debris falling close to the North pole. Determination to rebuild the satellite and carry out the mission was extremely widespread: within 6 months all of the necessary funding issues, legal procedures, industrial commitments and resource demands had been solved and the programme restarted. The new satellite, inevitably called CryoSat-2, includes a large number of improvements compared to its predecessor, although many are internal changes to improve the reliability and ease of operations. More significantly, the expected lifetime has been increased. The satellite measurements will be supported by a comprehensive set of validation data, collected on the surface and from airborne platforms. These validation data, designed to specifically address the uncertainties in the interpretation of the radar echoes, have been collected during a series of carefully co- ordinated measurement campaigns over several years. Additionally, techniques to enable the collocation of surface and satellite measurements over the moving sea-ice have been developed and rehearsed, ready to support the dedicated validation campaigns during the mission. CryoSat-2 is near completion, less than 3 years after the start of the industrial contract. Launch was originally planned for March 2009, again with a Rockot. But lack of availability of this vehicle (more specifically, the versatile third stage added to the ICBM) has induced a change to the Dnepr launcher, also an ICBM: the SS- 18. As a result of this change the launch is now planned for November 2009. So finally, about 10 years after it was first selected, the CryoSat mission will start collecting data.

Francis, R.; Cullen, R.

2009-04-01

96

Development of the cryo-rotary joint for a HTS synchronous motor with Gd-bulk HTS field-pole magnets  

NASA Astrophysics Data System (ADS)

We have studied a prototype of an axial-gap type synchronous motor with Gd-bulk HTS field-pole magnets since 2001. At the liquid nitrogen temperature, these bulks have trapped over 1 T inside the motor after being applied the pulsed field magnetization method. Increasing the flux of the field poles is the most straightforward way of improving the output power of the motor. Cooling down the bulk HTS magnets below the liquid nitrogen temperature provides an effective alternative to increase the magnetic flux trapping. In 2007, we exchanged the cryogen from liquid nitrogen to condensed neon. The key technology of this challenge is a rotary joint, introducing a fluid cryogen into the rotating body in the motor from the static reservoir. We have successfully developed a compact rotary joint which is smaller and lighter than the existent one (1/10 volume, 1/3 length and 1/12 weight). The present joint was manufactured and evaluated with liquid nitrogen and condensed neon. We presume a total heat loss of this rotary joint of less than 10 watts. Successful cooling and rotating tests of the bulk-HTS motor with this novel rotary joint are conducted.

Miki, M.; Felder, B.; Tsuzuki, K.; Izumi, M.; Hayakawa, H.

2010-06-01

97

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

98

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

99

Continuous separation of non-magnetic particles through negative magnetophoresis inside ferrofluids  

Microsoft Academic Search

We present a simple, low-cost, effective, and label-free continuous flow non-magnetic microparticle separation scheme in a microfluidic device under static magnetic fields. The separation process is based on negative magnetophoresis and uses water-based ferrofluids. We exploit the difference in particle sizes to achieve continuous binary separation of fluorescent microparticles with high throughput and efficiency. We demonstrate size-based separation (2.1 ?m

Taotao Zhu; Francisco Marrero; Leidong Mao

2010-01-01

100

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

101

Continuous sheath-free magnetic separation of particles in a U-shaped microchannel  

PubMed Central

Particle separation is important to many chemical and biomedical applications. Magnetic field-induced particle separation is simple, cheap, and free of fluid heating issues that accompany electric, acoustic, and optical methods. We develop herein a novel microfluidic approach to continuous sheath-free magnetic separation of particles. This approach exploits the negative or positive magnetophoretic deflection to focus and separate particles in the two branches of a U-shaped microchannel, respectively. It is applicable to both magnetic and diamagnetic particle separations, and is demonstrated through the sorting of 5??m and 15??m polystyrene particles suspended in a dilute ferrofluid.

Liang, Litao; Xuan, Xiangchun

2012-01-01

102

Continuous sheath-free magnetic separation of particles in a U-shaped microchannel.  

PubMed

Particle separation is important to many chemical and biomedical applications. Magnetic field-induced particle separation is simple, cheap, and free of fluid heating issues that accompany electric, acoustic, and optical methods. We develop herein a novel microfluidic approach to continuous sheath-free magnetic separation of particles. This approach exploits the negative or positive magnetophoretic deflection to focus and separate particles in the two branches of a U-shaped microchannel, respectively. It is applicable to both magnetic and diamagnetic particle separations, and is demonstrated through the sorting of 5??m and 15??m polystyrene particles suspended in a dilute ferrofluid. PMID:24175006

Liang, Litao; Xuan, Xiangchun

2012-01-01

103

An integrated microfluidic platform for magnetic microbeads separation and confinement  

Microsoft Academic Search

An innovative microfluidic platform for magnetic beads manipulation is introduced, consisting of novel microfabricated 3D magnetic devices positioned in a microfluidic chamber. Each magnetic device comprises of an embedded actuation micro-coil in various design versions, a ferromagnetic pillar, a magnetic backside plate and a sensing micro-coil. The various designs of the micro-coils enable efficient magnetic beads trapping and concentration in

Qasem Ramadan; Victor Samper; Daniel P. Poenar; Chen Yu

2006-01-01

104

On-chip free-flow magnetophoresis: continuous flow separation of magnetic particles and agglomerates.  

PubMed

The separation of magnetic microparticles was achieved by on-chip free-flow magnetophoresis. In continuous flow, magnetic particles were deflected from the direction of laminar flow by a perpendicular magnetic field depending on their magnetic susceptibility and size and on the flow rate. Magnetic particles could thus be separated from each other and from nonmagnetic materials. Magnetic and nonmagnetic particles were introduced into a microfluidic separation chamber, and their deflection was studied under the microscope. The magnetic particles were 2.0 and 4.5 microm in diameter with magnetic susceptibilities of 1.12 x 10(-4) and 1.6 x 10(-4) m(3) kg(-1), respectively. The 4.5-microm particles with the larger susceptibility were deflected further from the direction of laminar flow than the 2.0-microm magnetic particles. Nonmagnetic 6-microm polystyrene beads, however, were not deflected at all. Furthermore, agglomerates of magnetic particles were found to be deflected to a larger extent than single magnetic particles. The applied flow rate and the strength and gradient of the applied magnetic field were the key parameters in controlling the deflection. This separation method has a wide applicability since magnetic particles are commonly used in bioanalysis as a solid support material for antigens, antibodies, DNA, and even cells. Free-flow magnetophoretic separations could be hyphenated with other microfluidic devices for reaction and analysis steps to form a micro total analysis system. PMID:15595866

Pamme, Nicole; Manz, Andreas

2004-12-15

105

Conformable Tile Method of Applying CryoCoat{sup TM} UL79 Insulation to Cryogenic Tanks  

SciTech Connect

A procedure for fabricating, forming, and bonding thin tiles of CryoCoat{sup TM} UL79 cryogenic insulation, a syntactic foam material, to a large curved surface was developed and its performance was verified. This effort was undertaken because of safety concerns for the Alpha Magnetic Spectrometer 02 (AMS-02) experiment, a space-based particle physics detector designed to search for antimatter, dark matter and the origin of cosmic rays in space. The key component of the detector is a large superconducting magnet, cooled to 1.8 K by superfluid helium. From ground safety and flight safety considerations, the system must be safe in the event of a sudden catastrophic loss of insulating vacuum. Previous testing showed that a thin layer of CryoCoat{sup TM} UL79 reduces the heat flux in the event of vacuum loss by nearly a factor of eight, which satisfies the safety concern. A practical method of applying a uniform 3 mm layer of CryoCoat{sup TM} UL79 insulation material to the helium vessel containing the superconducting magnet was developed for this requirement. The fabrication procedure was validated through application of CryoCoat{sup TM} UL79 on a prototype helium tank, which was subsequently tested at cryogenic temperatures. Because of these successful tests, NASA has accepted the conformable tile method for applying CryoCoat{sup TM} UL79 and has agreed that AMS-02 is safe to fly.

Francis, Will; Tupper, Mike [Composite Technology Development, Lafayette, CO, 80026 (United States); Harrison, Stephen [Space Cryomagnetics Ltd., Abingdon, OX14 3DB (United Kingdom)

2004-06-23

106

Characterisation of bicontinuous cubic liquid crystalline systems of phytantriol and water using cryo field emission scanning electron microscopy (cryo FESEM)  

Microsoft Academic Search

Cubosomes are a novel lipid particulate delivery system currently being investigated for drug delivery purposes. The present study investigates bicontinuous cubic liquid crystalline systems (bulk phase and cubosomes) formed by phytantriol and water using cryo field emission scanning electron microscopy (cryo FESEM). Previously cubosomes have been characterized by cryo transmission electron microscopy (cryo TEM) with small angle X-ray diffraction (SAXS)

S. B. Rizwan; Y.-D. Dong; B. J. Boyd; T. Rades; S. Hook

2007-01-01

107

Studies in cryo-immunology  

PubMed Central

Antibodies produced as a result of experimental cryosurgery were shown to be highly specific with regard to the tissue frozen and the species of origin. As a consequence of destructive freezing in the coagulating gland and seminal vesicle of the rabbit, antibody is produced which reacts with extracts of the seminal vesicle, coagulating, prostate and bulbo-urethral glands, but fails to react with rabbit serum or with extracts of testis, kidney, liver, thyroid, vagina, spleen, stomach, epididymis or synovium of the rabbit. It also fails to react with prostatic or related tissue of human, guinea-pig and rat. This spectrum of tissue and species specificity, along with the proof that this antibody is an autoantibody, indicates that the same antigenic material is responsible for this antibody response as was responsible for antibodies elicited by iso-immunization by injection of tissue extracts with complete Freund's adjuvant. Additional proof was obtained of this identity by use of purified fractions of rabbit prostatic tissue. Only one of the fractions was active with an antiserum produced by iso-immunization, and this same fraction was active with an antiserum produced by cryo-immunization. Although the same autoantigen seems to be involved, the autoantibody response to the freezing of tissue is initiated much more quickly, and rises to a maximum in a much shorter period, than the analogous autoantibody response that follows repeated intradermal injections. The cryo-immunization response is generally at a maximum within 7–10 days, whereas stimulation by injection requires a period of many weeks of repeated injections, before a similar level of antibody is reached. ImagesFIG. 2

Shulman, S.; Brandt, E. J.; Yantorno, C.

1968-01-01

108

Magnetic Microspheres Prepared by Redox Polymerization Used in a Cell Separation Based on Gangliosides  

Microsoft Academic Search

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 percent of which

Paul L. Kronick; Graham Lem. Campbell; Kenneth Joseph

1978-01-01

109

Glassy magnetic behavior in the phase-separated perovskite cobaltites  

Microsoft Academic Search

In this paper we demonstrate that the origin of the glassy behaviors (memory, aging, etc.) in the phase-separated perovskite cobaltites cannot be simply ascribed to intercluster interactions as the phase-separated manganites can. Instead, our study indicates that both the intercluster interactions and a spin glasslike phase contribute to the glassy behaviors. Thus, this study distinguishes the picture of phase separation

Yan-Kun Tang; Young Sun; Zhao-Hua Cheng

2006-01-01

110

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

111

Separation of Uranium from Nitric and Hydrochloric-Acid Solutions with Extractant-Coated Magnetic Microparticles  

Microsoft Academic Search

The magnetically assisted chemical separation (MACS) process utilizes selective magnetic microparticle composites to separate dissolved metals from solution. In this study, MACS particles were coated with neutral and acidic organophosphorus extractants,octyl(phenyl)-N,N-diisobutylcarbamoylmethyl phosphine oxide (CMPO), tributyl phosphate (TBP), trioctylphosphine oxide (TOPO), and bis(2-ethyl-hexyl)phosphoric acid (D2EHPA or HDEHP) and were evaluated for the separation of uranyl ions from nitric- and hydrochloric-acid solutions.

M. D. KAMINSKI; L. NUÑEZ

2000-01-01

112

HIGH-GRADIENT MAGNETIC SEPARATION FOR REMOVAL OF SULFUR FROM COAL  

EPA Science Inventory

The report gives results of a thorough physical, chemical, and magnetic characterization of a Pennsylvania coal from the Upper Freeport seam. The powdered coal was then subjected to high-gradient magnetic separations, as a function of magnetic field and fluid velocity, in both a ...

113

High gradient magnetic separation I: The removal of solids from shale oils  

Microsoft Academic Search

High gradient magnetic separations are effective in the removal of solid particles from shale oil streams. Several types of shale oils were studied that included a wide range of physical properties and retorting conditions. In order to optimize separator performance, the effects of flow velocity and temperature on solids removal were determined. A measure of separator capacity was obtained. Preliminary

K. M. Jeong; L. Petrakis; M. Takayasu; F. Friedlaender

1982-01-01

114

Magnetite/CdTe magnetic-fluorescent composite nanosystem for magnetic separation and bio-imaging  

NASA Astrophysics Data System (ADS)

A new synthesis protocol is described to obtain a CdTe decorated magnetite bifunctional nanosystem via dodecylamine (DDA) as cross linker. High resolution transmission electron microscopy (HRTEM), energy-dispersive x-ray spectroscopy (EDAX), vibrating sample magnetometry (VSM), Fourier transform infrared spectroscopy (FTIR), diffuse reflectance spectroscopy (DRS) and fluorescence microscopy are used to characterize the constitution, size, composition and physical properties of these superparamagnetic-fluorescent nanoparticles. These CdTe decorated magnetite nanoparticles were then functionalized with anti-epidermal growth factor receptor (EGFR) antibody to specifically target cells expressing this receptor. The EGFR is a transmembrane glycoprotein and is expressed on tumor cells from different tissue origins including human leukemic cell line Molt-4 cells. The magnetite-CdTe composite nanosystem is shown to perform excellently for specific selection, magnetic separation and fluorescent detection of EGFR positive Molt-4 cells from a mixed population. Flow cytometry and confocal laser scanning microscopy results show that this composite nanosystem has great potential in antibody functionalized magnetic separation and imaging of cells using cell surface receptor antibody.

Kale, Anup; Kale, Sonia; Yadav, Prasad; Gholap, Haribhau; Pasricha, Renu; Jog, J. P.; Lefez, Benoit; Hannoyer, Béatrice; Shastry, Padma; Ogale, Satishchandra

2011-06-01

115

High-yield cell separations using magnetic nanowires  

Microsoft Academic Search

Ferromagnetic nanowires are demonstrated as a new tool in performing high-yield, single step cell separations on cultures of mammalian cells. The nanowires are made by electrochemical deposition in nanoporous templates, and when added to cultures of 3T3 mouse fibroblast cells, the nanowires can readily bind to the cells. The effectiveness in cell separations of Ni nanowires 350 nm in diameter

Anne Hultgren; Monica Tanase; Christopher S. Chen; Daniel H. Reich

2004-01-01

116

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

117

Application of magnetic separation technology for the recovery of colemanite from plant tailings.  

PubMed

In this study, colemanite was recovered from tailings produced by the Kestelek (Turkey) Processing Plant by magnetic separation. Magnetic susceptibility measurements revealed that colemanite is diamagnetic in character whereas gangue minerals are weakly paramagnetic, apparently due to the presence of the iron-bearing silicates such as smectite and, to a less extent, illite. Three-stage magnetic separation tests were performed on the size fractions coarser than 75 microm produced from the tailings (31.52% B(2)O(3)) using a high-intensity permanent magnetic separator. Under the test conditions a colemanite concentrate with a B(2)O(3) content of 43.74% at 95.06% recovery was shown to be produced from the tailings. The mineralogical composition of the tailings appears to allow the removal of gangue minerals by magnetic separation and hence the production of a concentrate of commercial grade. PMID:18927062

Alp, Ibrahim

2008-10-01

118

Carbon nanotube clusters as universal bacterial adsorbents and magnetic separation agents.  

PubMed

The magnetic susceptibility and high bacterial affinity of carbon nanotube (CNT) clusters highlight their great potential as a magnetic bio-separation agent. This article reports the CNT clusters' capability as "universal" bacterial adsorbents and magnetic separation agents by designing and testing a multiwalled carbon nanotube (MWNT) cluster-based process for bacterial capturing and separation. The reaction system consisted of large clusters of MWNTs for bacterial capture and an external magnet for bio-separation. The designed system was tested and optimized using Escherichia coli as a model bacterium, and further generalized by testing the process with other representative strains of both gram-positive and gram-negative bacteria. For all strains tested, bacterial adsorption to MWNT clusters occurred spontaneously, and the estimated MWNT clusters' adsorption capacities were nearly the same regardless of the types of strains. The bacteria-bound MWNT clusters also responded almost instantaneously to the magnetic field by a rare-earth magnet (0.68 Tesla), and completely separated from the bulk aqueous phase and retained in the system. The results clearly demonstrate their excellent potential as highly effective "universal" bacterial adsorbents for the spontaneous adsorption of any types of bacteria to the clusters and as paramagnetic complexes for the rapid and highly effective magnetic separations. PMID:19856390

Moon, Hyung-Mo; Kim, Jin-Woo

2010-01-01

119

High resolution separations of nanoparticles with improved electrical and magnetic field flow fractionation  

NASA Astrophysics Data System (ADS)

Electrical and Magnetic Field Flow Fractionation (ElFFF, MFFF) methods are two rapidly developing separation and characterization techniques using electrical and magnetic fields that have not been regularly applied to nanoparticle fractionation, separation, and characterization. Currently, several limitations characteristic of both techniques prevent them from being widely used tools in the separation of nanoparticles. In this work, we address the main limitations of both techniques and develop methods to enhance their separation abilities, and particularly their application to nanoparticles. Specifically, one order of magnitude improvement is obtained in the separation capability of the Cyclical ElFFF systems. It is shown that high resolution separations of 15 and 40 nm gold nanoparticles can be achieved by Cyclical ElFFF, for which the separation of particles smaller than 100 nanometers was not demonstrated before. In addition, the first particle based modeling of Electrical Field Flow Fractionation (ElFFF) systems is demonstrated for the first time. The developed particle based simulation code allows visualization of individual particles inside the separation channel, which leads to a better understanding of ElFFF operation and mechanisms. The outputs of the simulation code show good agreement with the experimental results. We have also fabricated a new ElFFF system and tested it with four different channel heights to investigate the effect of channel height on the separation performance of the ElFFF systems. It is also shown for the first time that ElFFF can be used for the separation of magnetic nanoparticles. In previously reported studies, magnetic field driven techniques were used for the separation of magnetic particles. However, in this study, it is revealed that an electrical field driven technique can also be used for the separation of these nanoparticles. A new magnetic field flow fractionation (MFFF) system was designed and modeled using both finite element and particle based simulations. As a change from current magnetic FFF systems, which use static magnetic fields, the new system uses cyclical magnetic fields for the separation of the particles. Finally, a novel passive magnetic microfluidic mixer is designed and fabricated which produces high efficiency mixing at the microscale, without need of an active actuation mechanism.

Tasci, Tonguc Onur

120

Method for Purifying and Recovering Silk Proteins Using Magnetic Affinity Separation.  

National Technical Information Service (NTIS)

A method for the purification of recombinant silk proteins from a sample using magnetic affinity separation is described. The recombinant silk protein is expressed with an affinity tag which has a high binding affinity for an affinity ligand immobilized o...

C. Hoffmann K. Keller

2005-01-01

121

Technical Performance Comparison of Coal-Pyrite Flotation and High-Gradient Magnetic Separation.  

National Technical Information Service (NTIS)

The Coal Preparation Division of the Pittsburgh Mining Technology Center conducted an investigation to assess and compare the pyritic sulfur reduction potential of coal-pyrite flotation and high-gradient magnetic separation (HGMS). Tests were run on three...

R. E. Hucko K. J. Miller

1980-01-01

122

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

123

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...

124

A Novel Blind Separation Method in Magnetic Resonance Images  

PubMed Central

A novel global search algorithm based method is proposed to separate MR images blindly in this paper. The key point of the method is the formulation of the new matrix which forms a generalized permutation of the original mixing matrix. Since the lowest entropy is closely associated with the smooth degree of source images, blind image separation can be formulated to an entropy minimization problem by using the property that most of neighbor pixels are smooth. A new dataset can be obtained by multiplying the mixed matrix by the inverse of the new matrix. Thus, the search technique is used to searching for the lowest entropy values of the new data. Accordingly, the separation weight vector associated with the lowest entropy values can be obtained. Compared with the conventional independent component analysis (ICA), the original signals in the proposed algorithm are not required to be independent. Simulation results on MR images are employed to further show the advantages of the proposed method.

Gao, Jianbin; Xia, Qi; Yin, Lixue; Zhou, Ji; Du, Li

2014-01-01

125

Effect of anisotropy in temperature dynamics of magnetic phase separation in europium hexaboride  

NASA Astrophysics Data System (ADS)

The ESR measurements of the EuB6 single crystal samples were executed on frequency 9.25 GHz in TE102 rectangular cavity in the temperature range from 15 to 300 K. We used samples of identical form and size, but different crystallografic orientation to estimate their magnetization. At T = 30 - 40K was observed the magnetic phase separation, which, most likely, is accompanied also by charging separation. The anisotropy magnetization of more intensive magnetic phase (with anti-Kondo interaction) along the different crystallographic directions was found above a temperature of the ferromagnetic transition. We conclude that this result connect with existence the ferronic states and charging separation in the EuB6 single crystal. Estimations of angular distribution of the magnetic moment of ferrons in EuB6 are made.

Altshuler, T. S.; Goryunov, Yu V.; Shitsevalova, N. Yu; Dukhnenko, A.

2010-01-01

126

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

2005-02-01

127

Magnetic phase separation in europium hexaboride and its relation to the Kondo interaction  

NASA Astrophysics Data System (ADS)

Europium hexaboride single crystals have been investigated using the electron paramagnetic resonance at a frequency of 9.25 GHz in the temperature range 10 300 K. The magnetic phase separation of the spin system of europium ions Eu2+ is observed. The cause of the separation is the formation of the polarons of two types associated with the Kondo and anti-Kondo couplings of charge carriers of the valence and conduction bands, respectively, with the localized magnetic moments of Eu2+.

Al'Tshuler, T. S.; Goryunov, Yu. V.; Dukhnenko, A. V.; Shitsevalova, N. Yu.

2008-10-01

128

Magnetic microheaters for cell separation, manipulation, and lysing  

Microsoft Academic Search

Precise heating is important for biological culturing, biological characterization, and thermal lysis, while cellular manipulation has been an area of significant interest and has been explored by a variety of methods. In this work, we present a preliminary study of the use of metallic thermal probes. The probes were used for magnetophoresis and micromanipulation of magnetically labeled HeLa cells. The

Angelo Gaitas; Paddy French

2011-01-01

129

Shock and Current-Sheet Separation in Magnetic Shock Tubes  

Microsoft Academic Search

The problem of separation of a shock wave from the current driving it, is experimentally investigated over a wide range of Mach numbers in a single gas. In order to do this, a parallel plate shock tube was developed which produces repeatable shocks in hydrogen from Mach 20-180 at initial pressures from 75-460 ?Hg. In the present work, no preheating

F. Y. Sorrell

1969-01-01

130

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

2013-01-01

131

Pulverized coal beneficiation by dry type high gradient magnetic separation process  

Microsoft Academic Search

A novel dry type high gradient magnetic separation (HGMS) device comprising a fluidizing bed is studied for the purpose of the pulverized coal ice is examined related to powder size, gas velocity, amount of feed, processing time, wire size and repeated process. Chinese Coal in the size range of 44 and 297 ..mu..m in diameter with high magnetic susceptibility compared

T. Oda; Y. Kunisue; S. Masuda

1983-01-01

132

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

133

Separation of Uranium by an Extractant Encapsulated Magnetic Alginate Gels  

NASA Astrophysics Data System (ADS)

The aim of this work is to prepare environmentally friendly and practically applicable alginate magnetic biopolymers encapsulated tri-n-butyl phosphate (TBP) for the removal uranium ions. Some important process parameters such as initial pH, initial U(VI) concentration, adsorbent dosage, time, temperature and sorption isotherms for uranium uptake were studied and the thermodynamic parameters for U(VI) were determined.

Portakal, Z.; Gok, C.; Aytas, S.

134

Structure and photocatalytic performance of magnetically separable titania photocatalysts for the degradation of propachlor  

Microsoft Academic Search

A magnetic photocatalyst was prepared by modification of TiO2 nanoparticles (Degussa P25) with nanocrystalline ?-Fe2O3 nanoparticles through a protective lining made up of two oppositely charged polyelectrolytes. As-prepared magnetically separable photocatalysts differing in ?-Fe2O3 loading (3, 8, 13, 20 and 30wt.%) were characterized by XRD, TEM, thermal analysis, Mössbauer and magnetic measurements. The photocatalytic efficiency of the nanocomposite catalysts was

V. Belessi; D. Lambropoulou; I. Konstantinou; R. Zboril; J. Tucek; D. Jancik; T. Albanis; D. Petridis

2009-01-01

135

A novel blind separation method in magnetic resonance images.  

PubMed

A novel global search algorithm based method is proposed to separate MR images blindly in this paper. The key point of the method is the formulation of the new matrix which forms a generalized permutation of the original mixing matrix. Since the lowest entropy is closely associated with the smooth degree of source images, blind image separation can be formulated to an entropy minimization problem by using the property that most of neighbor pixels are smooth. A new dataset can be obtained by multiplying the mixed matrix by the inverse of the new matrix. Thus, the search technique is used to searching for the lowest entropy values of the new data. Accordingly, the separation weight vector associated with the lowest entropy values can be obtained. Compared with the conventional independent component analysis (ICA), the original signals in the proposed algorithm are not required to be independent. Simulation results on MR images are employed to further show the advantages of the proposed method. PMID:24707318

Gao, Jianbin; Xia, Qi; Yin, Lixue; Zhou, Ji; Du, Li; Fan, Yunfeng

2014-01-01

136

An on-chip magnetic bead separator using spiral electromagnets with semi-encapsulated permalloy  

Microsoft Academic Search

A new planar bio-magnetic bead separator on a glass chip has been designed, fabricated and tested. The separator is composed of micromachined semi-encapsulated spiral electromagnets and fluid channels, which have been separately fabricated and then bonded. The device was tested with super-paramagnetic beads of mean diameter 1 ?m which were suspended in a buffered solution. When a DC current of

Jin-Woo Choi; Trifon M. Liakopoulos; Chong H. Ahn

2001-01-01

137

High gradient magnetic separation; I: the removal of solids from shale oils  

SciTech Connect

High gradient magnetic separations are effective in the removal of solid particles from shale oil streams. Several types of shale oils were studied that included a wide range of physical properties and retorting conditions. In order to optimize separator performance, the effects of flow velocity and temperature on solids removal were determined. A measure of separator capacity was obtained. Preliminary solids characterization data are also discussed.

Jeong, K.M.; Friedlaender, F.J.; Petrakis, L.; Takayasu, M.

1982-11-01

138

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

139

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

140

Aligning effect of magnetic field on PDLC films during the phase separation  

NASA Astrophysics Data System (ADS)

The results ofthe study ofthe uniaxially oriented PDLC films prepared by solvent induced phase separation (SIPS) method are presented. The samples were obtained applying a longitudinal magnetic field while the phase separation of the liquid crystal and polymer occurs due to the evaporation of common solvent from the uniform solution. In the presence of magnetic field the nematic liquid crystals 4-n-pentyl-4' -cyanophenylcyclohexane (5PCH), the 4-n-pentyl-4'- cyanobiphenyl (SCB) and nematic mixture LN-394 form the separate droplets in polyvinylbutyral (PVB) matrix. At that, the nematics 5PCH and LN-394 form always the stable bipolar structures with the order parameter of the droplet axes depending on the value of the applied field. In 5CB droplets the bipolar structure is realized only in a weak magnetic field and the radial one is formed in a strong magnetic field. At intermediate field the non-equilibrium structures are appeared that are characterized by the flickering textures.

Nazarov, V. G.; Parshin, A. M.; Zyryanov, V. Y.; Shabanov, V. F.; Lapanik, V. I.; Bezborodov, V. S.

2007-06-01

141

D0 Cryo Instrument Air Backup System  

Microsoft Academic Search

The D0 instrument air system for cryo controls has an emergency backup supply of nitrogen gas. The backup system consists of a high pressure tube trailer (38 tubes - 2400 psig MAWP), piping, valves, regulators and pressure monitoring instrumentation. The trailer is located south of DAB alongside the LN Dewar. Fixed piping ties to the trailer with a flex-hose. The

J. Urbin

1990-01-01

142

Selective loss of progenitor subsets following clinical CD34+ cell enrichment by magnetic field, magnetic beads or chromatography separation  

Microsoft Academic Search

In this preclinical evaluation we have compared the efficacy of three clinical CD34+enrichment procedures with respect to purity, yield and recovery, as well as risk of selective loss of CD34+ lineage-specific subsets. The three devices work by different principles and have several different manipulation steps: The magnetic field separator uses paramagnetic iron-dextran particles; the magnetic microbead selection is based on

HE Johnsen; M Hutchings; E Taaning; T Rasmussen; LM Knudsen; SW Hansen; H Andersen; E Gaarsdal; L Jensen; K Nikolajsen; E Kjæsgård; NE Hansen

1999-01-01

143

Direct observation of magnetically induced phase separation in Co-W sputtered thin films  

NASA Astrophysics Data System (ADS)

Phase separation of Co-W sputtered thin films having a large magnetocrystalline anisotropy energy have been investigated. A nanoscale compositional fluctuation caused by magnetically induced phase separation was directly confirmed in the films deposited on a heated substrate in analogy with Co-Cr-based alloys. The difference between the phase separation features in Co-W and Co-Cr is attributed to the difference in their elastic energy. It is expected that the phase separation is enhanced by selecting optimum sputtering conditions. The Co-W system, therefore, is considered to be a promising candidate as a base alloy system for high-density recording media.

Oikawa, K.; Qin, G. W.; Sato, M.; Okamoto, S.; Kitakami, O.; Shimada, Y.; Fukamichi, K.; Ishida, K.; Koyama, T.

2004-09-01

144

Optimisation of magnetic separation: A case study for soil washing at a heavy metals polluted site.  

PubMed

Sandy loam soil polluted with heavy metals (As, Cu, Pb and Zn) from an ancient Mediterranean Pb mining and metallurgy site was treated by means of wet high-intensity magnetic separation to remove some of the pollutants therein. The treated fractions were chemically analysed and then subjected to magnetic characterisation, which determined the high-field specific (mass), magnetic susceptibility (?) and the specific (mass) saturation magnetisation (?S), through isothermal remanent magnetisation (IRM) curves. From the specific values of ? and ?S, a new expression to assess the performance of the magnetic separation operation was formulated and verified by comparison with the results obtained by traditional chemical analysis. The magnetic study provided valuable information for the exhaustive explanation of the operation, and the deduced mathematical expression was found to be appropriate to estimate the performance of the separation operation. From these results we determined that magnetic soil washing was effective for the treatment of the contaminated soil, concentrating the majority of the heavy metals and peaking its separation capacity at 60% of the maximum output voltage. PMID:24418067

Sierra, C; Martínez-Blanco, D; Blanco, Jesús A; Gallego, J R

2014-07-01

145

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

146

Setting up High Gradient Magnetic Separation for combating eutrophication of inland waters.  

PubMed

To find new approaches to devise technologies for handling with eutrophication of inland waters is a global challenge. Separation of the P from water under conditions of continuous flow is proposed as an alternative and effective method. This work is based on using highly magnetic particles as the seeding adsorbent material and their later removal from solution by High Gradient Magnetic Separation (HGMS). Contrast to other methods based on batch conditions, large volumes of water can be easily handled by HGMS because of decreasing retention times. This study identifies the best working conditions for removing P from solution by investigating the effects of a set of four different experimental variables: sonication time, flow rate (as it determines the retention time of particles in the magnetic field), magnetic field strength and the iron (Fe) particles/P concentration ratio. Additionally, the change of P removal efficiency with time (build up effect) and the possibility of reusing magnetic particles were also studied. Our results evidenced that while flow rate does not significantly affect P removal efficiency in the range 0.08-0.36 mL s(-1), sonication time, magnetic field strength and the Fe particles/P concentration ratio are the main factors controlling magnetic separation process. PMID:21255924

Merino-Martos, A; de Vicente, J; Cruz-Pizarro, L; de Vicente, I

2011-02-28

147

Imaging endosomes and autophagosomes in whole mammalian cells using correlative cryo-fluorescence and cryo-soft X-ray microscopy (cryo-CLXM)?  

PubMed Central

Cryo-soft X-ray tomography (cryo-SXT) is a powerful imaging technique that can extract ultrastructural information from whole, unstained mammalian cells as close to the living state as possible. Subcellular organelles including the nucleus, the Golgi apparatus and mitochondria have been identified by morphology alone, due to the similarity in contrast to transmission electron micrographs. In this study, we used cryo-SXT to image endosomes and autophagosomes, organelles that are particularly susceptible to chemical fixation artefacts during sample preparation for electron microscopy. We used two approaches to identify these compartments. For early and recycling endosomes, which are accessible to externally-loaded markers, we used an anti-transferrin receptor antibody conjugated to 10 nm gold particles. For autophagosomes, which are not accessible to externally-applied markers, we developed a correlative cryo-fluorescence and cryo-SXT workflow (cryo-CLXM) to localise GFP-LC3 and RFP-Atg9. We used a stand-alone cryo-fluorescence stage in the home laboratory to localise the cloned fluorophores, followed by cryo-soft X-ray tomography at the synchrotron to analyse cellular ultrastructure. We mapped the 3D ultrastructure of the endocytic and autophagic structures, and discovered clusters of omegasomes arising from ‘hotspots’ on the ER. Thus, immunogold markers and cryo-CLXM can be used to analyse cellular processes that are inaccessible using other imaging modalities.

Duke, Elizabeth M.H.; Razi, Minoo; Weston, Anne; Guttmann, Peter; Werner, Stephan; Henzler, Katja; Schneider, Gerd; Tooze, Sharon A.; Collinson, Lucy M.

2014-01-01

148

Imaging endosomes and autophagosomes in whole mammalian cells using correlative cryo-fluorescence and cryo-soft X-ray microscopy (cryo-CLXM).  

PubMed

Cryo-soft X-ray tomography (cryo-SXT) is a powerful imaging technique that can extract ultrastructural information from whole, unstained mammalian cells as close to the living state as possible. Subcellular organelles including the nucleus, the Golgi apparatus and mitochondria have been identified by morphology alone, due to the similarity in contrast to transmission electron micrographs. In this study, we used cryo-SXT to image endosomes and autophagosomes, organelles that are particularly susceptible to chemical fixation artefacts during sample preparation for electron microscopy. We used two approaches to identify these compartments. For early and recycling endosomes, which are accessible to externally-loaded markers, we used an anti-transferrin receptor antibody conjugated to 10nm gold particles. For autophagosomes, which are not accessible to externally-applied markers, we developed a correlative cryo-fluorescence and cryo-SXT workflow (cryo-CLXM) to localise GFP-LC3 and RFP-Atg9. We used a stand-alone cryo-fluorescence stage in the home laboratory to localise the cloned fluorophores, followed by cryo-soft X-ray tomography at the synchrotron to analyse cellular ultrastructure. We mapped the 3D ultrastructure of the endocytic and autophagic structures, and discovered clusters of omegasomes arising from 'hotspots' on the ER. Thus, immunogold markers and cryo-CLXM can be used to analyse cellular processes that are inaccessible using other imaging modalities. PMID:24238600

Duke, Elizabeth M H; Razi, Minoo; Weston, Anne; Guttmann, Peter; Werner, Stephan; Henzler, Katja; Schneider, Gerd; Tooze, Sharon A; Collinson, Lucy M

2014-08-01

149

Proton-nuclear magnetic resonance study of water solvent magnetic fluid's phase separation  

Microsoft Academic Search

We report proton-nuclear magnetic resonance experiments on a diluted water solvent magnetic fluid of colloidal volume fraction phi=0.30%. By sweeping the external magnetic field strength, H0, applied to the magnetic fluid around 4000 Oe, we found one major resonant field, HM, and two satellite resonant fields, HS1 and HS2, which correspond to resonant protons in three different coexisting phases. HS1

Susamu Taketomi; Shin-Hachiro Saito

2000-01-01

150

Botryococcus braunii cells: Ultrasound-intensified outdoor cultivation integrated with in situ magnetic separation.  

PubMed

An integrated system combining ultrasound-intensified outdoor cultivation of Botryococcus braunii with in situ magnetic harvesting of the algal cells was developed. The algal cells were cultivated in 200L plastic bag reactors, and seven five-minute ultrasonic treatments at a four-day interval using a fixed frequency of 40kHz and a total power of 300W improved algal cell biomass and hydrocarbon productivity. The algal cells were harvested using functional magnetic particles and a magnetic separator, and a recovery efficiency of 90% was obtained under continuous operation at a flow rate of 100mL/min using the in situ magnetic separation system. The overall production cost using the integrated system was US$ 25.14 per kilogram of B. braunii dry biomass. The system developed in this study provides a base for the industrial production of B. braunii. PMID:24998478

Wang, Shi-Kai; Wang, Feng; Stiles, Amanda R; Guo, Chen; Liu, Chun-Zhao

2014-09-01

151

Tools for correlative cryo-fluorescence microscopy and cryo-electron tomography applied to whole mitochondria in human endothelial cells.  

PubMed

Cryo-electron tomography (cryo-ET) allows for the visualization of biological material in a close-to-native state, in three dimensions and with nanometer scale resolution. However, due to the low signal-to-noise ratio inherent to imaging of the radiation-sensitive frozen-hydrated samples, it appears often times impossible to localize structures within heterogeneous samples. Because a major potential for cryo-ET is thereby left unused, we set out to combine cryo-ET with cryo-fluorescence microscopy (cryo-FM), in order to facilitate the search for structures of interest. We describe a cryo-FM setup and workflow for correlative cryo-fluorescence and cryo-electron microscopy (cryo-CLEM) that can be easily implemented. Cells are grown on finder grids, vitally labeled with one or two fluorescent dyes, and vitrified. After a structure is located by cryo-FM (with 0.4microm resolution), its image coordinates are translated to cryo-ET stage coordinates via a home-built software routine. We tested our workflow on whole mount primary human umbilical vein endothelial cells. The correlative routine enabled us to investigate mitochondrial ultrastructure for the first time on intact human mitochondria, and led us to find mitochondrial cristae that were connected to the intermembrane space via large slits, which challenges the current view that such connections are established exclusively via small circular pores. Taken together, this study emphasizes that cryo-CLEM can be a routinely used technique that opens up exciting new possibilities for cryo-ET. PMID:19726102

van Driel, Linda F; Valentijn, Jack A; Valentijn, Karine M; Koning, Roman I; Koster, Abraham J

2009-11-01

152

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

2013-11-21

153

Thermal diffusion of magnetic nanoparticles in ferrocolloids: Experiments on particle separation in vertical columns  

Microsoft Academic Search

Experiments on nonstationary separation of nanometer-sized Fe3O4 particles of hydrocarbon-based ferrocolloids in a flat vertical thermal diffusion column are performed. By using a modified separation theory which accounts for an one-dimensional mixed (thermal and concentration) convection in the column, the Soret coefficient of magnetic nanoparticles are calculated. It is shown that particles are transferred in the direction of decreasing temperature.

Elmars Blums; Ansis Mezulis; Michail Maiorov; Gunars Kronkalns

1997-01-01

154

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

155

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

156

Correlated cryo-fluorescence and cryo-electron microscopy with high spatial precision and improved sensitivity.  

PubMed

Performing fluorescence microscopy and electron microscopy on the same sample allows fluorescent signals to be used to identify and locate features of interest for subsequent imaging by electron microscopy. To carry out such correlative microscopy on vitrified samples appropriate for structural cryo-electron microscopy it is necessary to perform fluorescence microscopy at liquid-nitrogen temperatures. Here we describe an adaptation of a cryo-light microscopy stage to permit use of high-numerical aperture objectives. This allows high-sensitivity and high-resolution fluorescence microscopy of vitrified samples. We describe and apply a correlative cryo-fluorescence and cryo-electron microscopy workflow together with a fiducial bead-based image correlation procedure. This procedure allows us to locate fluorescent bacteriophages in cryo-electron microscopy images with an accuracy on the order of 50 nm, based on their fluorescent signal. It will allow the user to precisely and unambiguously identify and locate objects and events for subsequent high-resolution structural study, based on fluorescent signals. PMID:24275379

Schorb, Martin; Briggs, John A G

2014-08-01

157

Design of large aperture superferric quadrupole magnets for an in-flight fragment separator  

NASA Astrophysics Data System (ADS)

Superferric quadrupole magnets to be used for in-flight fragment separator have been designed. A quadrupole magnet triplet for beam focusing is placed in a cryostat together with superconducting correction coils. To maximize acceptance of rare isotope beams produced by projectile fragmentation, it is essential to use large-aperture quadrupole magnets. The pole tip radius is 17 cm in the current design, and we tried to enlarge the aperture with 3D analysis on magnetic fields. In the front end of the separator, where a target and beam dump are located, we plan to use two sets of quadrupole triplets made of high-Tc superconductor (HTS) operating at 20-50 K considering high radiation heat load. The HTS magnet will use warm iron poles. Both low-Tc and high-Tc superconductors are acquired for test winding, and two kinds of dewar and cryostat are under construction to perform the coil and magnet tests. The magnetic design of superferric quadrupole is mainly discussed.

Zaghloul, Aziz; Kim, Dogyun; Kim, Jangyoul; Kim, Mijung; Kim, Myeongjin; Yun, Chongcheoul; Kim, Jongwon

2014-01-01

158

Imaging protein three-dimensional nanocrystals with cryo-EM.  

PubMed

Flash-cooled three-dimensional crystals of the small protein lysozyme with a thickness of the order of 100 nm were imaged by 300 kV cryo-EM on a Falcon direct electron detector. The images were taken close to focus and to the eye appeared devoid of contrast. Fourier transforms of the images revealed the reciprocal lattice up to 3 Å resolution in favourable cases and up to 4 Å resolution for about half the crystals. The reciprocal-lattice spots showed structure, indicating that the ordering of the crystals was not uniform. Data processing revealed details at higher than 2 Å resolution and indicated the presence of multiple mosaic blocks within the crystal which could be separately processed. The prospects for full three-dimensional structure determination by electron imaging of protein three-dimensional nanocrystals are discussed. PMID:23633595

Nederlof, Igor; Li, Yao Wang; van Heel, Marin; Abrahams, Jan Pieter

2013-05-01

159

The CryoCapsule: simplifying correlative light to electron microscopy.  

PubMed

Correlating complementary multiple scale images of the same object is a straightforward means to decipher biological processes. Light microscopy and electron microscopy are the most commonly used imaging techniques, yet despite their complementarity, the experimental procedures available to correlate them are technically complex. We designed and manufactured a new device adapted to many biological specimens, the CryoCapsule, that simplifies the multiple sample preparation steps, which at present separate live cell fluorescence imaging from contextual high-resolution electron microscopy, thus opening new strategies for full correlative light to electron microscopy. We tested the biological application of this highly optimized tool on three different specimens: the in vitro Xenopus laevis mitotic spindle, melanoma cells over-expressing YFP-langerin sequestered in organized membranous subcellular organelles and a pigmented melanocytic cell in which the endosomal system was labeled with internalized fluorescent transferrin. PMID:24533564

Heiligenstein, Xavier; Heiligenstein, Jérôme; Delevoye, Cédric; Hurbain, Ilse; Bardin, Sabine; Paul-Gilloteaux, Perrine; Sengmanivong, Lucie; Régnier, Gilles; Salamero, Jean; Antony, Claude; Raposo, Graca

2014-06-01

160

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

161

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

162

High intensity magnetic separation for the clean-up of a site polluted by lead metallurgy.  

PubMed

The industrial history in the district of Linares (Spain) has had a severe impact on soil quality. Here we examined soil contaminated by lead and other heavy metals in "La Cruz" site, a brownfield affected by metallurgical residues. Initially, the presence of contaminants mainly associated with the presence of lead slag fragments mixed with the soil was evaluated. The subsequent analysis showed a quasi-uniform distribution of the pollution irrespective of the grain-size fractions. This study was accompanied by a characterization of the lead slag behavior under the presence of a magnetic field. Two main magnetic components were detected: first a ferromagnetic and/or ferrimagnetic contribution, second a paramagnetic and/or antiferromagnetic one. It was also established that the slag was composed mainly of lead spherules and iron oxides embedded in a silicate matrix. Under these conditions, the capacity of magnetic separation to remove pollutants was examined. Therefore, two high intensity magnetic separators (dry and wet devices, respectively) were used. Dry separation proved to be successful at decontaminating soil in the first stages of a soil washing plant. In contrast, wet separation was found effective as a post-process for the finer fractions. PMID:23357508

Sierra, C; Martínez, J; Menéndez-Aguado, J M; Afif, E; Gallego, J R

2013-03-15

163

Separation and enrichment of enantiopure from racemic compounds using magnetic levitation.  

PubMed

Crystallization of a solution with high enantiomeric excess can generate a mixture of crystals of the desired enantiomer and the racemic compound. Using a mixture of S-/RS-ibuprofen crystals as a model, we demonstrated that magnetic levitation (MagLev) is a useful technique for analysis, separation and enantioenrichment of chiral/racemic products. PMID:24875274

Yang, Xiaochuan; Wong, Shin Yee; Bwambok, David K; Atkinson, Manza B J; Zhang, Xi; Whitesides, George M; Myerson, Allan S

2014-06-17

164

Sustained Magnetic Fields Reveal Separate Sites for Sound Level and Temporal Regularity in Human Auditory Cortex  

Microsoft Academic Search

Magnetoencephalographywas used to investigate the relationship between the sustained magnetic field in auditory cortex and the perception of periodic sounds. The response to regular and irregular click trains was measured at three sound intensities. Two separate sources were isolated adjacent to primary auditory cortex: One, located in lateral Heschl's gyrus, was particularly sensitive to regularity and largely insensitive to sound

Alexander Gutschalk; Roy D. Patterson; André Rupp; Stefan Uppenkamp; Michael Scherg

2002-01-01

165

APPLICATION OF HIGH-GRADIENT MAGNETIC SEPARATION TO FINE PARTICLE CONTROL  

EPA Science Inventory

The report gives results of an assessment of the potential use of high-gradient magnetic separation (HGMS) as a means of collecting gas stream particulates. The assessment included both experiments and analyses of theoretical models. Phase I included evaluations of theoretical ex...

166

Separable constrained nonlinear least squares and an application in magnetic resonance spectroscopy  

Microsoft Academic Search

An application in magnetic resonance spectroscopy (MRS) quantification models a signal as a linear combination of nonlinear functions. It leads to a separable nonlinear least squares fitting problem, with linear bound constraints on some variables. The Variable Projection (VARPRO) (1) technique can be applied to this problem, but needs to be adapted in several respects. If only the nonlinear variables

Diana M. Sima

167

A method to obtain uniform magnetic-field energy density gradient distribution using discrete pole pieces for a microelectromechanical-system-based magnetic cell separator  

Microsoft Academic Search

A spatially uniform magnetic energy density gradient (?B2) distribution offers a controlled environment to separate magnetically tagged cells or biomolecules based on their magnetophoretic mobility [L. R. Moore et al., J. Biochem. Biophys. Methods 37, 11 (1998)]. A design to obtain a uniform ?B2 distribution for a microelectromechanical-systems-based magnetic cell separator was developed. The design consists of an external magnetic

Pulak Nath; Lee R. Moore; Maciej Zborowski; Shuvo Roy; Aaron Fleischman

2006-01-01

168

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

169

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

170

Conformable Tile Method of Applying CryoCoat™ UL79 Insulation to Cryogenic Tanks  

Microsoft Academic Search

A procedure for fabricating, forming, and bonding thin tiles of CryoCoat™ UL79 cryogenic insulation, a syntactic foam material, to a large curved surface was developed and its performance was verified. This effort was undertaken because of safety concerns for the Alpha Magnetic Spectrometer 02 (AMS-02) experiment, a space-based particle physics detector designed to search for antimatter, dark matter and the

Will Francis; Mike Tupper; Stephen Harrison

2004-01-01

171

Conformable Tile Method of Applying CryoCoat{sup TM} UL79 Insulation to Cryogenic Tanks  

Microsoft Academic Search

A procedure for fabricating, forming, and bonding thin tiles of CryoCoat{sup TM} UL79 cryogenic insulation, a syntactic foam material, to a large curved surface was developed and its performance was verified. This effort was undertaken because of safety concerns for the Alpha Magnetic Spectrometer 02 (AMS-02) experiment, a space-based particle physics detector designed to search for antimatter, dark matter and

Will Francis; Mike Tupper; Stephen Harrison

2004-01-01

172

Improvement of Immunomagnetic Separation for Escherichia coli O157:H7 Detection by the PickPen Magnetic Particle Separation Device  

Microsoft Academic Search

Conventional immunomagnetic separation (IMS) procedures, which use an external magnetic source to capture magnetic particles against the side of a test tube, are labor-intensive and can have poor sensitivity for the target organism because of high background microflora that is not effectively washed away during the IMS process. This report compares the conventional IMS procedure to a new IMS procedure

XIANGWU NOU; TERRANCE M. ARTHUR; JOSEPH M. BOSILEVAC; DAYNA M. BRICHTA-HARHAY; MICHAEL N. GUERINI; NORASAK KALCHAYANAND; MOHAMMAD KOOHMARAIE

2006-01-01

173

On-chip free-flow magnetophoresis: Separation and detection of mixtures of magnetic particles in continuous flow  

NASA Astrophysics Data System (ADS)

The complete separation of mixtures of magnetic particles was achieved by on-chip free-flow magnetophoresis. In continuous flow, magnetic particles were deflected from the direction of laminar flow by a perpendicular magnetic field depending on their magnetic susceptibility and size and on the flow rate. 2.8 and 4.5 ?m superparamagnetic particles with magnetic susceptibilities of 1.1×10 -4 and 1.6×10 -4 m 3 kg -1, respectively, could be completely separated from each other reproducibly. The separated particles were detected by video observation and also by on-chip laser light scattering. Potential applications of this separation method include sorting of magnetic micro- and nanoparticles as well as magnetically labelled cells.

Pamme, Nicole; Eijkel, Jan C. T.; Manz, Andreas

2006-12-01

174

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

2013-07-30

175

Physical and Structural Studies on the Cryo-cooling of Insulin Crystals  

NASA Technical Reports Server (NTRS)

Reflection profiles were analyzed from microgravity-(mg) and earth-grown insulin crystals to measure mosaicity (h) and to reveal mosaic domain structure and composition. The effects of cryocooling on single and multi-domain crystals were compared. The effects of cryocooling on insulin structure were also re-examined. Microgravity crystals were larger, more homogeneous, and more perfect than earth crystals. Several mg crystals contained primarily a single mosaic domain with havg of 0.005deg. The earth crystals varied in quality and all contained multiple domains with havg of 0.031deg. Cryocooling caused a 43-fold increase in h for mg crystals (havg=0.217deg) and an %fold increase for earth crystals (havg=0.246deg). These results indicate that very well-ordered crystals are not completely protected from the stresses associated with cryocooling, especially when structural perturbations occur. However, there were differences in the reflection profiles. For multi-mosaic domain crystals, each domain individually broadened and separated from the other domains upon cryo-cooling. Cryo-cooling did not cause an increase in the number of domains. A crystal composed of a single domain retained this domain structure and the reflection profiles simply broadened. Therefore, an improved signal-to-noise ratio for each reflection was measured from cryo-cooled single domain crystals relative to cryo-cooled multi-domain crystals. This improved signal, along with the increase in crystal size, facilitated the measurement of the weaker high- resolution reflections. The observed broadening of reflection profiles indicates increased variation in unit cell dimensions which may be linked to cryo-cooling-associated structural changes and disorder.

Lovelace, J.; Bellamy, H.; Snell, E. H.; Borgstahl, G.

2003-01-01

176

Isolation of osteoprogenitors from human jaw periosteal cells: a comparison of two magnetic separation methods.  

PubMed

Human jaw periosteum tissue contains osteoprogenitors that have potential for tissue engineering applications in oral and maxillofacial surgeries. To isolate osteoprogenitor cells from heterogeneous cell populations, we used the specific mesenchymal stem cell antigen-1 (MSCA-1) antibody and compared two magnetic separation methods. We analyzed the obtained MSCA-1(+) and MSCA-1(-) fractions in terms of purity, yield of positive/negative cells and proliferative and mineralization potentials. The analysis of cell viability after separation revealed that the EasySep method yielded higher viability rates, whereas the flow cytometry results showed a higher purity for the MACS-separated cell fractions. The mineralization capacity of the osteogenic induced MSCA-1(+) cells compared with the MSCA-1(-) controls using MACS was 5-fold higher, whereas the same comparison after EasySep showed no significant differences between both fractions. By analyzing cell proliferation, we detected a significant difference between the proliferative potential of the osteogenic cells versus untreated cells after the MACS and EasySep separations. The differentiated cells after MACS separation adjusted their proliferative capacity, whereas the EasySep-separated cells failed to do so. The protein expression analysis showed small differences between the two separation methods. Our findings suggest that MACS is a more suitable separation method to isolate osteoprogenitors from the entire jaw periosteal cell population. PMID:23094035

Olbrich, Marcus; Rieger, Melanie; Reinert, Siegmar; Alexander, Dorothea

2012-01-01

177

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

178

Droplet-based magnetically activated cell separation: analysis of separation efficiency based on the variation of flow-induced circulation in a pendent drop  

Microsoft Academic Search

Under the assumption that separation efficiencies are mainly affected by the velocity of flow-induced circulation due to buffer\\u000a injection in a pendent drop, this paper describes an analysis of the separation efficiency of a droplet-based magnetically\\u000a activated cell separation (DMACS) system. To investigate the velocity of the flow-induced circulation, we supposed that numerous\\u000a flows in a pendent drop could be

Youngho Kim; Sang Ho Lee; Byungkyu Kim

2009-01-01

179

Tools for correlative cryo-fluorescence microscopy and cryo-electron tomography applied to whole mitochondria in human endothelial cells  

Microsoft Academic Search

Cryo-electron tomography (cryo-ET) allows for the visualization of biological material in a close-to-native state, in three dimensions and with nanometer scale resolution. However, due to the low signal-to-noise ratio inherent to imaging of the radiation-sensitive frozen-hydrated samples, it appears oftentimes impossible to localize structures within heterogeneous samples. Because a major potential for cryo-ET is thereby left unused, we set out

Linda F. van Driel; Jack A. Valentijn; Karine M. Valentijn; Roman I. Koning; Abraham J. Koster

2009-01-01

180

Hydrodynamic Separation of Magnetic Particles and Magnetically-Labeled Blood Cells in an Annular Channel in a Quadrupole Magnetic Field  

Microsoft Academic Search

A quadrupole magnetic field coupled with a flow in an axisymmetric annular thin channel is used for the continuous sorting of magnetic particles and of magnetically-labeled lymphocytes differing in magnetophoretic mobilities. The channel is composed of two concentric cylinders; in the thin annulus two flow splitters are placed at each extremity. The channel has two inlets and two outlets. Species

Mauricio Hoyos; Lee Moore; Kara McCloskey; Masayuki Nakamura; Jeffrey J. Chalmers; Maciej Zborowski

1999-01-01

181

On-chip free-flow magnetophoresis: Separation and detection of mixtures of magnetic particles in continuous flow  

Microsoft Academic Search

The complete separation of mixtures of magnetic particles was achieved by on-chip free-flow magnetophoresis. In continuous flow, magnetic particles were deflected from the direction of laminar flow by a perpendicular magnetic field depending on their magnetic susceptibility and size and on the flow rate. 2.8 and 4.5?m superparamagnetic particles with magnetic susceptibilities of 1.1×10?4 and 1.6×10?4m3kg?1, respectively, could be completely

Nicole Pamme; Jan C. T. Eijkel; Andreas Manz

2006-01-01

182

Magnetic Solid Sulfonic Acid Decorated with Hydrophobic Regulators: A Combinatorial and Magnetically Separable Catalyst for the Synthesis of ?-Aminonitriles.  

PubMed

A three-component, Strecker reaction of a series of aldehydes or ketones, amines, and trimethylsilyl cyanide for the synthesis of ?-aminonitriles in the presence of a catalytic amount of a magnetic solid sulfonic acid catalyst, Fe3O4@SiO2@Me&Et-PhSO3H under solvent-free conditions have been investigated. This catalyst, with a combination of hydrophobicity and acidity on the Fe3O4@SiO2 core-shell of the magnetic nanobeads, as well as its water-resistant property, enabled easy mass transfer and catalytic activity in the Strecker reaction. The catalyst was easily separated by an external magnet and the recovered catalyst was reused in 6 successive reaction cycles without any significant loss of activity. PMID:24932543

Mobaraki, Akbar; Movassagh, Barahman; Karimi, Babak

2014-07-14

183

Removal of malaria-infected red blood cells using magnetic cell separators: A computational study  

PubMed Central

High gradient magnetic field separators have been widely used in a variety of biological applications. Recently, the use of magnetic separators to remove malaria-infected red blood cells (pRBCs) from blood circulation in patients with severe malaria has been proposed in a dialysis-like treatment. The capture efficiency of this process depends on many interrelated design variables and constraints such as magnetic pole array pitch, chamber height, and flow rate. In this paper, we model the malaria-infected RBCs (pRBCs) as paramagnetic particles suspended in a Newtonian fluid. Trajectories of the infected cells are numerically calculated inside a micro-channel exposed to a periodic magnetic field gradient. First-order stiff ordinary differential equations (ODEs) governing the trajectory of particles under periodic magnetic fields due to an array of wires are solved numerically using the 1st –5th order adaptive step Runge-Kutta solver. The numerical experiments show that in order to achieve a capture efficiency of 99% for the pRBCs it is required to have a longer length than 80 mm; this implies that in principle, using optimization techniques the length could be adjusted, i.e., shortened to achieve 99% capture efficiency of the pRBCs.

Kim, Jeongho; Massoudi, Mehrdad; Antaki, James F.; Gandini, Alberto

2012-01-01

184

Measurement of the magnetic interaction between two bound electrons of two separate ions.  

PubMed

Electrons have an intrinsic, indivisible, magnetic dipole aligned with their internal angular momentum (spin). The magnetic interaction between two electronic spins can therefore impose a change in their orientation. Similar dipolar magnetic interactions exist between other spin systems and have been studied experimentally. Examples include the interaction between an electron and its nucleus and the interaction between several multi-electron spin complexes. The challenge in observing such interactions for two electrons is twofold. First, at the atomic scale, where the coupling is relatively large, it is often dominated by the much larger Coulomb exchange counterpart. Second, on scales that are substantially larger than the atomic, the magnetic coupling is very weak and can be well below the ambient magnetic noise. Here we report the measurement of the magnetic interaction between the two ground-state spin-1/2 valence electrons of two (88)Sr(+) ions, co-trapped in an electric Paul trap. We varied the ion separation, d, between 2.18 and 2.76 micrometres and measured the electrons' weak, millihertz-scale, magnetic interaction as a function of distance, in the presence of magnetic noise that was six orders of magnitude larger than the magnetic fields the electrons apply on each other. The cooperative spin dynamics was kept coherent for 15 seconds, during which spin entanglement was generated, as verified by a negative measured value of -0.16 for the swap entanglement witness. The sensitivity necessary for this measurement was provided by restricting the spin evolution to a decoherence-free subspace that is immune to collective magnetic field noise. Our measurements show a d(-3.0(4)) distance dependence for the coupling, consistent with the inverse-cube law. PMID:24943952

Kotler, Shlomi; Akerman, Nitzan; Navon, Nir; Glickman, Yinnon; Ozeri, Roee

2014-06-19

185

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

186

Optimizing the coating process of organic actinide extractants on magnetically assisted chemical separation particles.  

SciTech Connect

The coatings of ferromagnetic-charcoal-polymer microparticles (1-25 gm) with organic extractants specific for actinides were optimized for use in the magnetically assisted chemical separation (MACS) process. The organic extractants, octyl (phenyl)-N,N-diisobutylcarbamoylmethylphosphine oxide (CMPO) dissolved in tributyl phosphate (TBP), coated the particles when a carrier organic solvent was evaporated. Coated particles were heated in an oven overnight to drive off any remaining carrier solvent and fix the extractants on the particles. Partitioning coefficients for americium obtained with the coated particles routinely reached 3000-4000 ml g-1, approximately 10 times the separation efficiency observed with the conventional solvent extraction system using CMPO and TBP.

Buchholz, B. A.; Tuazon, H. E.; Kaminski, M. D.; Aase, S. B.; Nunez, L.; Vandegrift, G. F.; Chemical Engineering; LLNL; California State Polytechnic Univ. at Pomona; Univ. of Illinois; Univ. of Illinois at Chicago

1997-01-01

187

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

2013-08-01

188

On chip cell separator using magnetic bead-based enrichment and depletion of various surface markers  

Microsoft Academic Search

This paper presents an on-chip magnetic cell sorting system for the sorting of cells based on a variety of surface markers.\\u000a A polymer lab on a chip integrated with an electroplated array of Ni\\/Fe permalloy has been designed, fabricated, and characterized\\u000a for the separation of cell substitutes at a variety of flow rates and incubation times. The system sequentially labels

Matthew D. Estes; Chong H. Ahn

2009-01-01

189

Design of a cellular-uptake-shielding magnetic catcher for cancer cell separation.  

PubMed

Fluorescent-magnetic-biotargeting multifunctional microcapsules (FMBMMs) are designed and fabricated via layer-by-layer assembly. It is found that the arginine-glycine-aspartate-modified FMBMMs were capable of sensitively detecting and efficiently isolating approximately 80% target cancer cells within 20 min. More importantly, FMBMMs present a general template for identifying and separating multiple types of cancer cells simply by altering the recognition motif. PMID:22965892

Wang, Ya; Zhang, Jing; Jia, Hui-Zhen; Yang, Juan; Qin, Si-Yong; Liu, Chen-Wei; Zhuo, Ren-Xi; Zhang, Xian-Zheng

2012-10-01

190

Antibody conjugated magnetic iron oxide nanoparticles for cancer cell separation in fresh whole blood  

Microsoft Academic Search

A highly efficient process using iron oxide magnetic nanoparticles (IO)-based immunomagnetic separation of tumor cells from fresh whole blood has been developed. The process involved polymer coated 30 nm IO that was modified with antibodies (Ab) against human epithelial growth factor receptor 2 (anti-HER2 or anti-HER2\\/neu) forming IO-Ab. HER2 is a cell membrane protein that is overexpressed in several types of

Hengyi Xu; Zoraida P. Aguilar; Lily Yang; Min Kuang; Hongwei Duan; Yonghua Xiong; Hua Wei; Andrew Wang

2011-01-01

191

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

192

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

Microsoft Academic Search

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

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

2010-01-01

193

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

194

ATOMIC RESOLUTION CRYO ELECTRON MICROSCOPY OF MACROMOLECULAR COMPLEXES  

PubMed Central

Single-particle cryo electron microscopy (cryoEM) is a technique for determining three-dimensional (3D) structures from projection images of molecular complexes preserved in their “native,” noncrystalline state. Recently, atomic or near-atomic resolution structures of several viruses and protein assemblies have been determined by single-particle cryoEM, allowing ab initio atomic model building by following the amino acid side chains or nucleic acid bases identifiable in their cryoEM density maps. In particular, these cryoEM structures have revealed extended arms contributing to molecular interactions that are otherwise not resolved by the conventional structural method of X-ray crystallography at similar resolutions. High-resolution cryoEM requires careful consideration of a number of factors, including proper sample preparation to ensure structural homogeneity, optimal configuration of electron imaging conditions to record high-resolution cryoEM images, accurate determination of image parameters to correct image distortions, efficient refinement and computation to reconstruct a 3D density map, and finally appropriate choice of modeling tools to construct atomic models for functional interpretation. This progress illustrates the power of cryoEM and ushers it into the arsenal of structural biology, alongside conventional techniques of X-ray crystallography and NMR, as a major tool (and sometimes the preferred one) for the studies of molecular interactions in supramolecular assemblies or machines.

ZHOU, Z. HONG

2013-01-01

195

ELCS in ice: cryo-electron microscopy of nuclear envelope-limited chromatin sheets.  

PubMed

Nuclear envelope-limited chromatin sheets (ELCS) form during excessive interphase nuclear envelope growth in a variety of cells. ELCS appear as extended sheets within the cytoplasm connecting distant nuclear lobes. Cross-section stained images of ELCS, viewed by transmission electron microscopy, resemble a sandwich of apposed nuclear envelopes separated by ?30 nm, containing a layer of parallel chromatin fibers. In this study, the ultrastructure of ELCS was compared by three different methods: (1) aldehyde fixation/dehydration/plastic embedding/sectioning and staining, (2) high-pressure freezing/freeze substitution into plastic/sectioning and staining, and (3) high-pressure freezing/cryo-sectioning/cryo-electron microscopy. ELCS could be clearly visualized by all three methods and, consequently, must exist in vivo and are not fixation artifacts. The ?30-nm chromatin fibers could only be observed following aldehyde fixation; none were seen in cryo-sections. Electron microscopic tomography tangential views of aldehyde-fixed ELCS suggested an ordering of the separate chromatin fibers adjacent to the nuclear envelope. Possible mechanisms of this chromatin ordering are discussed. PMID:24570264

Eltsov, Mikhail; Sosnovski, Sergey; Olins, Ada L; Olins, Donald E

2014-06-01

196

Heavy medium recovery in coal washing by continuous high gradient magnetic separation. Final report  

SciTech Connect

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..m (avg. size) magnetite without entraining 2 mm coal has been incorporated in a 1.85 m diameter continuous high gradient magnetic separator. Three-quarter ton samples of magnetite (in 1000 gallons of water) have been recovered with the matrix ring turning at 40 cm/s through a field of 6 kOe. A laminated core demagnetizing coil followed by water sprays removes the recovered magnetite. The recovery is high, particularly for two passes which could be accomplished by two magnet heads on a single carousel ring. Coal entrainment is low for a wide range of operating conditions. A 4.8 m diameter separator, the largest currently available, with multiple heads, should be able to treat 350 tons of magnetite and coal per hour. 29 references, 52 figures, 13 tables.

Kelland, D.R.

1983-09-01

197

Magnetization reversal and nanoscopic magnetic-phase separation in La1-x Srx CoO3  

NASA Astrophysics Data System (ADS)

The doped perovskite cobaltite La1-x Srx CoO3 (LSCO) has been advanced as a model system for studying intrinsic magnetic phase separation. We have employed a first-order reversal curve (FORC) method to probe the amount of irreversible switching in bulk polycrystalline LSCO as a function of Sr doping, field cooling procedure, and temperature. The value of the FORC distribution ? is used as a measure of the extent of irreversible switching. For x<0.18 , the small values of ? and its ridgelike distribution along local coercivity ( Hc ) and zero bias ( Hb ) are characteristic of noninteracting single domain particles. This is consistent with the formation of an array of isolated nanoscopic ferromagnetic clusters, as observed in previous work. For x?0.18 , the much larger values of ? , the tilting of its distribution towards negative bias field, and the emergence of regions with negative ? are consistent with increased long-range ferromagnetic ordering. The FORC distributions display little dependence on the cooling procedure. With increasing temperature, the fraction of irreversible switching determined from the FORC distribution follows closely the ferromagnetic phase fraction measured by La nuclear magnetic resonance. Our results furthermore demonstrate that the FORC method is a valuable first-pass characterization tool for magnetic-phase separation.

Davies, Joseph E.; Wu, J.; Leighton, C.; Liu, Kai

2005-10-01

198

A novel human detoxification system based on nanoscale bioengineering and magnetic separation techniques.  

PubMed

We describe the conceptual approach, theoretical background and preliminary experimental data of a proposed platform technology for specific and rapid decorporation of blood-borne toxins from humans. The technology is designed for future emergent in-field or in-hospital detoxification of large numbers of biohazard-exposed victims; for example, after radiological attacks. The proposed systems is based on nanoscale technology employing biocompatible, superparamagnetic nanospheres, which are functionalized with target-specific antitoxin receptors, and freely circulate within the human blood stream after simple intravenous injection. Sequestration of the blood-borne toxins onto the nanosphere receptors generates circulating nanosphere-toxin complexes within a short time interval; mathematical modeling indicates prevailing of unbound nanosphere receptors over target toxin concentrations at most therapeutic injection dosages. After a toxin-specific time interval nanosphere-toxin complexes are generated within the blood stream and, after simple arterial or venous access, the blood is subsequently circulated via a small catheter through a portable high gradient magnetic separator device. In this device, the magnetic toxin complexes are retained by a high gradient magnetic field and the detoxified blood is then returned back to the blood circulation (extracorporeal circulation). Our preliminary in vitro experiments demonstrate >95% first pass capture efficiency of magnetic spheres within a prototype high gradient magnetic separation device. Further, based on the synthesis of novel hydrophobic magnetite nanophases with high magnetization ( approximately 55 emu/g), the first biodegradable magnetic nanospheres at a size range of approximately 280 nm and functionalized with PEG-maleimide surface groups for specific antibody attachment are described here. In future applications, we envision this technology to be suitable for emergent, in-field usage for acutely biohazard exposed victims as both the injectable toxin-binding magnetic spheres and the separator device are made to be portable, light-weight, zero-power, and self- or helper-employed. Details of the technology are presented and the state-of-knowledge and research is discussed. PMID:17123743

Chen, Haitao; Kaminski, Michael D; Liu, Xianqiao; Mertz, Carol J; Xie, Yumei; Torno, Michael D; Rosengart, Axel J

2007-01-01

199

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

2012-05-01

200

Phase transitions in a ferrofluid at magnetic-field-induced microphase separation.  

PubMed

In the presence of a magnetic field applied perpendicular to a thin sample layer, a suspension of magnetic colloidal particles (ferrofluid) can form spatially modulated phases with a characteristic length determined by the competition between dipolar forces and short-range forces opposing density variations. We introduce models for thin-film ferrofluids in which magnetization and particle density are viewed as independent variables and in which the nonmagnetic properties of the colloidal particles are described either by a lattice-gas entropy or by the Carnahan-Starling free energy. Our description is particularly well suited to the low-particle-density regions studied in many experiments. Within mean-field theory, we find isotropic, hexagonal and stripe phases, separated in general by first-order phase boundaries. PMID:11690032

Lacoste, D; Lubensky, T C

2001-10-01

201

Conjugates of Magnetic Nanoparticle -- Actinide Specific Chelator for Radioactive Waste Separation  

SciTech Connect

A novel nanotechnology for the separation of radioactive waste that uses magnetic nanoparticles (MNPs) conjugated with actinide specific chelators (MNP-Che) is reviewed with a focus on design and process development. The MNP-Che separation process is an effective way of separating heat generating minor actinides (Np, Am, Cm) from spent nuclear fuel solution to reduce the radiological hazard. It utilizes coated MNPs to selectively adsorb the contaminants onto their surfaces, after which the loaded particles are collected using a magnetic field. The MNP-Che conjugates can be recycled by stripping contaminates into a separate, smaller volume of solution, and then become the final waste form for disposal after reusing number of times. Due to the highly selective chelators, this remediation method could be both simple and versatile while allowing the valuable actinides to be recovered and recycled. Key issues standing in the way of large-scale application are stability of the conjugates and their dispersion in solution to maintain their unique properties, especially large surface area, of MNPs. With substantial research progress made on MNPs and their surface functionalization, as well as development of environmentally benign chelators, this method could become very flexible and cost-effective for recycling used fuel. Finally, the development of this nanotechnology is summarized and its future direction is discussed.

Maninder Kaur; Huijin Zhang; Leigh Martin; Terry Todd; You Qiang

2013-11-01

202

Nanomagnetism of Core-Shell Magnetic Nanoparticles and Application in Spent Nuclear Fuel Separation  

NASA Astrophysics Data System (ADS)

This dissertation presents the study on novel core-shell magnetic nanoparticles (NPs) with unique magnetic properties. Understanding the fundamental physics of antiferromagnetic - ferromagnetic interactions is essential to apply in different applications. Chromium (Cr) doped and undoped core-shell iron/iron-oxide NPs have been synthesized using cluster deposition system and studied with respect to their nanostructures, morphologies, sizes, chemical composition and magnetic properties. The room-temperature magnetic properties of Fe based NPs shows the strong dependence of intra/inter-particle interaction on NP size. The Cr-doped Fe NP shows the origin of sigma-FeCr phase at very low Cr concentration (2 at.%) unlike others reported at high Cr content and interaction reversal from dipolar to exchange interaction. A theoretical model of watermelon is constructed based on the experimental results and core-shell NP system in order to explain the physics of exchange interaction in Cr-doped Fe particles. The magnetic nanoparticle---chelator separation nanotechnology is investigated for spent nuclear fuel recycling and is reported 97% and 80% of extraction for Am(III) and Pu(IV) actinides respectively. If the long-term heat generating actinides such as Am(III) can be efficiently removed from the used fuel raffinates, the volume of material that can be placed in a given amount of repository space can be significantly increased. As it is a simple, versatile, compact, and cost efficient process that minimizes secondary waste and improves storage performance.

Tarsem Singh, Maninder Kaur

203

Preparation of magnetic molecularly imprinted polymers for separating rutin from Chinese medicinal plants.  

PubMed

The preparation of magnetic molecularly imprinted polymers (MMIPs) which can be used for the separation and purification of rutin from Chinese medicinal plants has been proposed. By applying the improved co-precipitation method, magnetic Fe(3)O(4) particles were easily prepared, followed by the modification of TEOS and functionalization with -CH=CH(2). Using functionalized Fe(3)O(4) particles as the magnetic cores, rutin as the template, and acrylamide as the functional monomer, MMIPs were synthesized by surface-imprinted polymerization under the protection of nitrogen gas and successive mechanical stirring at 60 °C for 24 h. Magnetic non-molecularly imprinted polymers (MNIPs) were also prepared with the same synthesis procedure as with MMIPs only without the presence of rutin. Magnetic particles were characterized by FT-IR, XRD, and TG analysis. And the selectivity of MMIPs was also investigated in detail. In addition, the performance of the MMIPs for the adsorption of rutin in the analysis of Chinese medicinal plants was assessed. The mean recoveries were 84.33% (RSD: 3.22%, n = 3) for Saururus chinensis (Lour.) Bail and 85.20% (RSD: 3.58%, n = 3) for Flos Sophorae, respectively, which showed that the prepared MMIPs with many advantages possess the value of practical application. PMID:22489285

Zeng, Huan; Wang, Yuzhi; Nie, Chan; Kong, Jinhuan; Liu, Xiaojie

2012-05-21

204

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

NASA Astrophysics Data System (ADS)

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 10 10/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 immuno-magnetically 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.

2009-05-01

205

Selective recognition and separation of nucleosides using carboxymethyl-?-cyclodextrin functionalized hybrid magnetic nanoparticles.  

PubMed

A novel magnetic nanoadsorbent (CMCD-APTS-MNPs) containing the superparamagnetic and molecular recognition properties was synthesized by grafting carboxymethyl-?-cyclodextrin (CM-?-CD) on 3-aminopropyltriethoxysile (APTS) modified Fe(3)O(4) nanoparticles. The feasibility of using CMCD-APTS-MNPs as magnetic nanoadsorbent for selective adsorption of adenosine (A) and guanosine (G) based on inclusion and molecular recognition was demonstrated. The as-synthesized magnetic nanoparticles were characterized by TEM, FTIR and TGA analyses. The effects of pH and initial nucleoside concentrations on the adsorption behavior were studied. The complexation of CMCD-APTS-MNPs with both nucleosides was found to follow the Langmuir adsorption isotherm. The CMCD-APTS-MNPs showed a higher adsorption ability and selectivity for G than A under identical experimental conditions, which results from the ability of selective binding and recognition of the immobilized CM-?-CD towards G. The driving force of the separation between G and A is through the different weak interaction with grafted CM-?-CD, i.e., hydrogen bond interaction, which is evidenced by different inclusion equilibrium constants and FTIR analyses of inclusion complexes between grafted cyclodextrin and the guest molecules. Our results indicated that this nanoadsorbent would be a promising tool for easy, fast and selective separation, analysis of nucleosides and nucleotides in biological samples. PMID:22177539

Badruddoza, A Z M; Junwen, L; Hidajat, K; Uddin, M S

2012-04-01

206

Effective antifouling using quorum-quenching acylase stabilized in magnetically-separable mesoporous silica.  

PubMed

Highly effective antifouling was achieved by immobilizing and stabilizing an acylase, disrupting bacterial cell-to-cell communication, in the form of cross-linked enzymes in magnetically separable mesoporous silica. This so-called "quorum-quenching" acylase (AC) was adsorbed into spherical mesoporous silica (S-MPS) with magnetic nanoparticles (Mag-S-MPS), and further cross-linked for the preparation of nanoscale enzyme reactors of AC in Mag-S-MPS (NER-AC/Mag-S-MPS). NER-AC effectively stabilized the AC activity under rigorous shaking at 200 rpm for 1 month, while free and adsorbed AC lost more than 90% of their initial activities in the same condition within 1 and 10 days, respectively. When applied to the membrane filtration for advanced water treatment, NER-AC efficiently alleviated the biofilm maturation of Pseudomonas aeruginosa PAO1 on the membrane surface, thereby enhancing the filtration performance by preventing membrane fouling. Highly stable and magnetically separable NER-AC, as an effective and sustainable antifouling material, has a great potential to be used in the membrane filtration for water reclamation. PMID:24601563

Lee, Byoungsoo; Yeon, Kyung-Min; Shim, Jongmin; Kim, Sang-Ryoung; Lee, Chung-Hak; Lee, Jinwoo; Kim, Jungbae

2014-04-14

207

Effect of microwave irradiation on selective heating behavior and magnetic separation characteristics of Panzhihua ilmenite  

NASA Astrophysics Data System (ADS)

The influences of microwave irradiation on the surface characteristics of Panzhihua ilmenite were systematically investigated. The crystal structures, surface morphology and surface chemical functional groups of ilmenite were characterized before and after microwave irradiation and magnetic separation for different microwave treatment times by using various methods, such as XRD, SEM, and FT-IR, respectively. XRD analysis showed that the microwave treated ilmenite has the strongest peaks of phase more than that of raw samples, indicates that the crystalline compound of ilmenite increased with the microwave irradiation time. SEM analysis showed the micro-cracking appeared at many grain boundaries of ilmenite after being pretreated by microwave treatment. The separations of ilmenite from gangue minerals were completed and the micro-fissure within ilmenite minerals were also formed, which could be attributed to the microwave selective heating characteristics of the different minerals and compounds, and the thermal stresses were caused by the uniform heat rate disturbed under microwave irradiation. The mineral processing results showed that the magnetic separation characteristics and properties of microwave treated ilmenite samples were better than that of microwave untreated ilmenite samples. It was concluded that microwave irradiation can be applied effectively and efficiently to the irradiation processes of Panzhihua ilmenite.

Zhao, Wei; Chen, Jin; Chang, Xiaodong; Guo, Shenghui; Srinivasakannan, C.; Chen, Guo; Peng, Jinhui

2014-05-01

208

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

209

Cryo-Field Emission Scanning Electron Microscopy Imaging of a Rigid Surfactant Mesophase  

PubMed Central

The aerosol OT/l-?-phosphatidylcholine/isooctane/water system forms a rigid mesophase that transitions from reverse hexagonal to multilamellar in structure at specific water contents. This study shows that characteristics of ordered liquid-crystalline mesophases can be distinguished and imaged in high clarity using cryo-field emission scanning electron microscopy (cryo-FESEM). The reverse hexagonal phase consists of bundles of long cylinders, some with length scales of over 2 ?m, that are randomly oriented as part of a larger domain. Cryo-imaging allows the visualization of the intercylinder spacings and the details of transitions from one domain to another. The multilamellar structured mesophase consists of spherical vesicles of 100 nm to 10 ?m in diameter, with intervening noncrystalline isotropic regions. Coexistence regions containing both the reverse hexagonal and lamellar structures are also observed in the transition from the reverse hexagonal to the lamellar phase. These results complement and qualitatively verify our earlier studies with small-angle neutron scattering, high-field nuclear magnetic resonance spectroscopy, and freeze-fracture direct imaging transmission electron microscopy. The information is useful in understanding materials templating in these rigid systems.

Tan, Grace; Xu, Peng; John, Vijay T.; He, Jibao; McPherson, Gary L.; Agarwal, Vivek; Bose, Arijit

2009-01-01

210

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

SciTech Connect

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{reg_sign}. 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, H.; Bockenfeld, D.; Rempfer, D.; Kaminski, M. D.; Rosengart, A. J.; Chemical Engineering; Univ. of Chicago; Illinois Inst. of Tech.

2007-09-07

211

4D cryo-electron microscopy of proteins.  

PubMed

Cryo-electron microscopy is a form of transmission electron microscopy that has been used to determine the 3D structure of biological specimens in the hydrated state and with high resolution. We report the development of 4D cryo-electron microscopy by integrating the fourth dimension, time, into this powerful technique. From time-resolved diffraction of amyloid fibrils in a thin layer of vitrified water at cryogenic temperatures, we were able to detect picometer movements of protein molecules on a nanosecond time scale. Potential future applications of 4D cryo-electron microscopy are numerous, and some are discussed here. PMID:24313395

Fitzpatrick, Anthony W P; Lorenz, Ulrich J; Vanacore, Giovanni M; Zewail, Ahmed H

2013-12-26

212

Magnetic-field-induced nematic-nematic phase separation and droplet formation in colloidal goethite.  

PubMed

We demonstrate the suitability of polarization microscopy to study the recently discovered (parallel) nematic-(perpendicular) nematic phase separation. This novel type of phase transition is induced by applying an external magnetic field to a nematic liquid crystal of boardlike colloidal goethite and is due to an interplay between the intrinsic magnetic properties of goethite and the collective effect of liquid crystal formation. It is shown that the intense ochre colour of goethite does not preclude the use of polarization microscopy and interference colours, and that dichroism can give valuable qualitative information on the nature of the phases, their anchoring and their sedimentation and order parameter profiles. We also apply these techniques to study 'nematic-nematic tactoids': nematic droplets sedimenting within a nematic medium with mutually perpendicular orientations. PMID:21525548

van den Pol, E; Verhoeff, A A; Lupascu, A; Diaconeasa, M A; Davidson, P; Dozov, I; Kuipers, B W M; Thies-Weesie, D M E; Vroege, G J

2011-05-18

213

Magnetic resonance assessment of iron overload by separate measurement of tissue ferritin and hemosiderin iron  

PubMed Central

With transfusional iron overload, almost all the excess iron is sequestered intracellularly as rapidly mobilizable, dispersed, soluble, ferritin iron, and as aggregated, insoluble hemosiderin iron for long-term storage. Established magnetic resonance imaging (MRI) indicators of tissue iron (R2, R2*) are principally influenced by hemosiderin iron and change slowly, even with intensive iron chelation. Intracellular ferritin iron is evidently in equilibrium with the low-molecular-weight cytosolic iron pool that can change rapidly with iron chelation. We have developed a new magnetic resonance imaging (MRI) method to separately measure ferritin and hemosiderin iron, based on the non-monoexponential signal decay induced by aggregated iron in multiple-spin-echo sequences. We have initially validated the method in agarose phantoms and in human liver explants and shown the feasibility of its application in patients with thalassemia major. Measurement of tissue ferritin iron is a promising new means to rapidly evaluate the effectiveness of iron-chelating regimens.

Wu, Ed X.; Kim, Daniel; Tosti, Christina L.; Tang, Haiying; Jensen, Jens H.; Cheung, Jerry S.; Feng, Li; Au, Wing-Yan; Ha, Shau-Yin; Sheth, Sujit S.; Brown, Truman R.; Brittenham, Gary M.

2010-01-01

214

Solution for MEG inverse problem using Signal Space Separation and Magnetic Field Tomography  

NASA Astrophysics Data System (ADS)

Magnetic Field Tomography (MFT) is a source localization method for Magnetoencephalography (MEG), a non-invasive method to observe the brain activity. MFT just requires the source to be a linear combination of lead fields that describe the distribution of the sensitivity of each sensor, while other commonly used MEG source localization methods such as equivalent current dipole (ECD) fitting or the beamformer require some more inappropriate assumptions. However, less requirements on the source results in a huge amount of computational load in MFT. In this paper, the reduction of the computational load for MFT was achieved by considering the coefficients of multipolar expansion as the measurements of virtual sensors. These coefficients are obtained by performing Signal Space Separation (SSS) in which the exclusion of external magnetic field generated by the external sensor arrays is enabled. Based on our simulation, the calculation time was reduced from 6 hours to about 10 seconds preserving the source localization ability.

Kitahara, Tadashi; Honda, Satoshi

2011-06-01

215

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

PubMed Central

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; pI = 4.65) and lysozyme (LYZ; 14.3 kDa; pI = 11) were shown at the pH values corresponding to their own pI 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.

2012-01-01

216

Adaptive separation of regular and irregular magnetic activity for K indices  

NASA Astrophysics Data System (ADS)

A numerical-data adaptive-separation method is developed for the discrimination of quasi-regular magnetic variations from the irregular variations for the determination of the K indices. The method is based on a pattern comparison and discrimination technique using harmonic analyses and is more objective than the hand-scaling method. The method is tested on digital data from the Canadian magnetic observatories Victoria, Meanook, and Ottawa over a 4-month period. The data are at a 10-s sampling interval and encompass the full range of K values (0-9). The two methods were found to agree about 97 percent of the time, with most errors occurring during very irregular periods. This is comparable with values carefully determined by highly skilled observers. It is proposed that the method is suitable for use on a regular basis.

Walker, J. K.

1987-10-01

217

Desulphurization of lignites by slow, fast, and flash pyrolysis and high intensity dry magnetic separation  

SciTech Connect

Slow, fast and flash pyrolysis followed by high intensity dry magnetic (HIDM) separation experiments were conducted to obtain improved solid fuels. Pyrolysis experiments were performed in three different apparatus, and important parameters of processes, temperature, particle size, residence time and heating rate were studied to determine the optimum conditions. Desulphurization of lignites by flash pyrolysis is more successful than slow and fast pyrolysis. At optimum conditions of pyrolysis, up to 58.15, 60.24, and 62.31% sulphur reductions were obtained in slow, fast and flash pyrolysis, respectively. Char, obtained from the pyrolysis experiments, was further cleaned by a Permroll HIDM separator. Sulphur reduction enhanced up to 82.68, 84.40, and 86.55% in the char of slow, fast and flash pyrolysis, respectively.

Koca, H.; Kockar, O.M.; Koca, S. [Anadolu University, Eskisehir (Turkey). Porsuk Technical College

2007-07-01

218

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

219

Utilization of magnetic and electrostatic separation in the recycling of printed circuit boards scrap.  

PubMed

The progress of the technology is directly related to the growth of production and consumption of electrical/electronics equipment, especially of personal computers. This type of equipment has a relatively short average lifetime, 2-3 years. The amount of defective or obsolete equipment has been increasing substantially; consequently its disposition and/or recycling should be studied. In this work, printed circuit boards, which are used in personal computers, were studied in order to recover the metals in the circuit boards through mechanical processing, such as crushing, screening, as well as magnetic and electrostatic separation. The results obtained demonstrate the feasibility of using these processes to separate metal fractions from polymers and ceramics, and that it is possible to obtain a fraction concentrated in metals containing more than 50% on average of copper, 24% of tin and 8% of lead. PMID:15681180

Veit, H M; Diehl, T R; Salami, A P; Rodrigues, J S; Bernardes, A M; Tenório, J A S

2005-01-01

220

CryoSat Data Quality Overview  

NASA Astrophysics Data System (ADS)

CryoSat data are routinely controlled by ESA-ESRIN-SPPA office with various tools and with the support of the IDEAS industrial consortium. This poster introduces to the structure of the data products, the available quality tools (Quality Checks and Monitoring Facility) and methodology, and shows the main statistical results from the data acquired since the end of the commissioning phase (January 2011). Due to some anomalies still present in the data, ESA is planning to operate a new version of the processors by the end of 2011, followed by a full reprocessing campaign in 2012. This poster presents the reprocessing schedule and the main improvements expected from the new release of the specialized processors at Level 1b and at Level 2.

Bouzinac, C.; Parrinello, T.; Féménias, P.; Fornari, M.; Mannan, R.

2011-12-01

221

CryoSat Data Quality Overview  

NASA Astrophysics Data System (ADS)

CryoSat data are routinely controlled by ESA-ESRIN-SPPA office with various tools and with the support of the IDEAS industrial consortium. This presentation introduces to the structure of the data products, the available quality tools (Quality Checks and Monitoring Facility) and methodology, and shows the main statistical results from the data acquired since the end of the commissioning phase (January 2011). Due to some anomalies still present in the data, ESA is planning to operate a new version of the processors by February 2012, followed by a full reprocessing campaign in 2012. This presentation details the reprocessing schedule and the main improvements expected from the new release of the specialized processors at Level 1b and at Level 2.

Bouzinac, C.; Femenias, P.; Parrinello, T.; Fornari, M.; Mannan, R.

2012-04-01

222

Simultaneous determination of ten organophosphate pesticide residues in fruits by gas chromatography coupled with magnetic separation.  

PubMed

In this study, ?-Fe2 O3 /chitosan magnetic microspheres were synthesized and evaluated by X-ray diffraction, SEM, thermogravimetric analysis, and static and kinetic adsorption experiments. Results showed that the magnetic microspheres exhibited good adsorption ability, and offered fast kinetics for the adsorption of trichlorfon, methamidophos, malathion, methyl parathion, dimethoate, omethoate, phosphamidon, phorate, isocarbophos, and chlorpyrifos. Based on magnetic separation, a simple method of magnetic SPE coupled to GC for the simultaneous determination of ten trace organophosphate pesticide residues was developed. Under the optimal conditions, the enrichment factor for ten organophosphorus pesticides was 10.1-364.7 and linear range was 0.001-10.0 mg/L. The LOD (S/N = 3) of the method for the ten pesticides was 0.31-3.59 ?g/kg. The RSD for three replicate extractions of spiked samples was between 2.5 and 6.3%. The pear and apple samples spiked with ten organophosphate pesticides at 20 and 200 ?g/kg levels were extracted and determined by this method with good recoveries ranging from 79.9 to 98.7%. Moreover, the method has been successfully applied for the determination of the ten organophosphate pesticide residues in peach samples. PMID:24470377

Tang, Qinghua; Wang, Xilong; Yu, Fan; Qiao, Xuguang; Xu, Zhixiang

2014-04-01

223

Orientation and Strain Dependence of the Magnetic Phase Separation at Perovskite Cobaltite Interfaces  

NASA Astrophysics Data System (ADS)

We recently showed that the degraded magnetic and electronic properties in very thin STO(001)/La1-xSrxCoO3 films is due to a form of magnetic phase separation. This is primarily due to the strain driven accumulation of O vacancies near the interface. In this work we demonstrate how this understanding allows us to engineer these interfacial properties via crystallographic orientation and strain control. Using PNR, magnetometry and transport, we show how this degradation can be significantly mitigated by using LAO(001) and STO(110) substrates cf. STO(001). PNR on 400å x=0.28 films reveals an interfacial layer with suppressed magnetism on all three substrates. However, while this layer is 150å on STO(001), it extends at most to 30å on LAO(001) and STO(110). Transport measurements on x=0.5 films show that at a thickness of ˜ 55å, films on STO(110) and LAO(001) exhibit AMR whereas films on STO(001) are dominated by inter-cluster GMR. Finally, thickness dependent magnetometry shows that the magnetic order deteriorates more quickly on STO(001) than on LAO(001) and STO(110). Our work thus opens up a possible new route to tailor interfacial magneto-electronic properties in oxide heterostructures.

Bose, S.; Sharma, M.; Torija, M. A.; Gazquez, J.; Varela, M.; Ambaye, H.; Goyette, R.; Lauter, V.; Fitzsimmons, M. R.; Schmitt, J.; Leighton, C.

2013-03-01

224

Initial exploration of application of open-gradient magnetic separation of coal to beneficiation of liquefaction feeds  

Microsoft Academic Search

Finely divided multi-component solids can be separated into multiple fractions by Open-Gradient Magnetic Separation if differences in magnetic susceptibility exist among the components. This technique has now been applied to several crushed coals, in particular to the 30-100 mesh cut. Coal fractions have been characterized by petrographic, mineralogical, and analytical data. As one proceeds from the most diamagnetic to the

M. L. Poutsma; L. A. Harris; E. C. Hise; R. M. Wham; J. E. Wortman

1983-01-01

225

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

PubMed

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 10(10) 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. PMID:20161001

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

2009-05-01

226

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

227

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

228

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

229

Mineralogy and heavy metal leachability of magnetic fractions separated from some Chinese coal fly ashes.  

PubMed

Magnetic fractions (MFs) in fly ashes from eight coal-burning power plants were extracted by magnetic separation procedure. Their mineralogy and potential leachability of heavy metals were analyzed using rock magnetism, X-ray diffraction (XRD), scanning electron microscopy equipped with energy-dispersive X-ray spectroscopy (SEM/EDX) and leaching procedures (toxicity characteristics leaching procedure by the United States Environmental Protection Agency, TCLP, and gastric juice simulation test, GJST). Results show that the MFs in the fly ashes range between 2.2 and 16.3wt%, and are generally composed of magnetite, hematite, quartz and mullite. Thermomagnetic analysis and SEM/EDX indicate that the main magnetic carrier magnetite is substituted with small amounts of impure ions, and its structures are featured by rough, dendritic and granular iron spherules. The MFs are found to be rich in Fe, Mn, Cr, Cu, Cd and Pb. Compared with the non-magnetic fractions (NMFs), the MFs have about 5 times higher iron, and 1.6 times higher Mn, Cr, Cu and Cd concentrations. The TCLP test shows that the TCLP-extractable Cr, Cu, and Pb concentrations in the MFs are higher than those in the NMFs, while the TCLP-extractable Cd concentration in the MFs and NMFs is below the detection limit (<0.1mg/L). The GJST-extractable Cd, Cr, Cu, and Pb concentrations in the MFs are higher those in the NMFs. No significant difference in the leachability ratio of Cr, Cu and Pb with TCLP and GJST is found in the MFs and NMFs. However, the GJST test showed that Pb has higher leachability in MFs than that in NMFs. The leachability ratio of heavy metals has an order of Cu>Cr>Pb>Cd. The heavy metals of fly ashes have a great potential to be released into the environment under acid environment. PMID:19380201

Lu, S G; Chen, Y Y; Shan, H D; Bai, S Q

2009-09-30

230

Quantification of Non-Specific Binding of Magnetic Micro and Nano particles using Cell Tracking Velocimetry: Implication for magnetic cell separation and detection  

PubMed Central

The maturation of magnetic cell separation technology places increasing demands on magnetic cell separation performance. While a number of factors can cause suboptimal performance, one of the major challenges can be non-specific binding of magnetic nano or micro particles to non-targeted cells. Depending on the type of separation, this non-specific binding can have a negative effect on the final purity, the recovery of the targeted cells, or both. In this work, we quantitatively demonstrate that non-specific binding of magnetic nanoparticles can impart a magnetization to cells such that these cells can be retained in a separation column and thus negatively impact the purity of the final product and the recovery of the desired cells. Through experimental data and theoretical arguments, we demonstrate that the number of MACS magnetic particles needed to impart a magnetization that is sufficient to causes non-targeted cells to be retained in the column to be on the order of 500 to 1,000 nanoparticles. This number of non-specifically bound particles was demonstrated experimentally with an instrument, cell tracking velocimeter, CTV, and it is demonstrated that the sensitivity of the CTV instrument for Fe atoms contained in magnetic nanoparticles on the order of 1 × 10?15 g/mL of Fe.

Chalmers, J.J.; Xiong, Y.; Jin, X.; Shao, M.; Tong, X.; Farag, S.; Zborowski, M.

2012-01-01

231

Development program for magnetically assisted chemical separation: Evaluation of cesium removal from Hanford tank supernatant  

SciTech Connect

Magnetic particles (MAG*SEP{sup SM}) coated with various absorbents were evaluated for the separation and recovery of low concentrations of cesium from nuclear waste solutions. The MAG*SEP{sup SM} particles were coated with (1) clinoptilolite, (2) transylvanian volcanic tuff, (3) resorcinol formaldehyde, and (4) crystalline silico-titanate, and then were contacted with a Hanford supernatant simulant. Particles coated with the crystalline silico-titanate were identified by Bradtec as having the highest capacity for cesium removal under the conditions tested (variation of pH, ionic strength, cesium concentration, and absorbent/solution ratio). The MAG*SEP{sup SM} particles coated with resorcinol formaldehyde had high distribution ratios values and could also be used to remove cesium from Hanford supernant simulant. Gamma irradiation studies were performed on the MAG*SEP{sup SM} particles with a gamma dose equivalent to 100 cycles of use. This irradiation decreased the loading capacity and distribution ratios for the particles by greater than 75%. The particles demonstrated high sensitivity to radiolytic damage due to the degradation of the polymeric regions. These results were supported by optical microscopy measurements. Overall, use of magnetic particles for cesium separation under nuclear waste conditions was found to be marginally effective.

Nunez, L.; Buchholz, B.A.; Ziemer, M.; Dyrkacz, G.; Kaminski, M.; Vandegrift, G.F. [Argonne National Lab., IL (United States); Atkins, K.J.; Bos, F.M.; Elder, G.R.; Swift, C.A.

1994-12-01

232

Synthesis of magnetic ion-imprinted composites and selective separation and preconcentration of U(VI).  

PubMed

The U(VI) magnetic ion-imprinted composite (MIIC) with a uniform core-shell structure for the selective separation and preconcentration of U(VI) was prepared by copolymerization of a ternary complex of uranyl ions with 4-vinylpyridine (4-VP) and acrylamide in the presence of 2,2'-azobisisobutyronitrile. The sorption of U(VI) on the MIIC from aqueous solution was evaluated. The maximum sorption capacity of MIIC for U(VI) was 354.85 mg g(-1), which was much higher than that of the magnetic nonimprinted composite. The MIIC could be recovered by desorbing the U(VI)-loaded MIIC with 0.5 mol L(-1) HNO3, and the surface morphology of MIIC after five consecutive sorption/desorption cycles was significantly damaged. The competitive sorption experiments showed that the MIIC had a desirable selectivity for U(VI) over a range of competing metal ions. The MIIC may be a promising sorbent material for the selective separation and preconcentration of U(VI). PMID:24667936

Liu, Mancheng; Chen, Changlun; Wen, Tao; Wang, Xiangke

2014-05-21

233

High-frequency magnetic field probe for determination of interface levels in separation tanks  

NASA Astrophysics Data System (ADS)

There are many principles for interface level detection in separation tanks based on capacitance, ultra sound, microwave, nuclear radiation etc. These principles work well in many situations, in others they fail. The high frequency magnetic field principle works in most of the situations that will occur in separation tanks for crude oils for detection of the clean water level, the layers of water continuous water/oil emulsion and the oil continuous oil/water emulsion, the oil level, the thickness of the foam layer and the gas. When a coil is dipped into a fluid its electrical impedance will be dependent on the characteristics of the fluid. If the material is electrical conductive the impedance of the coil will be reduced due to the eddy currents induced in the material, setting up a magnetic field directed against the field generated by the coil. The inductance will increase but still remain low also in the water continuous water/oil emulsion zone, but will rapidly increase in the oil continuous oil/water emulsion zone. In pure crude oil the inductance will be high and even higher in gas. The coil inductance is measured by connecting the coil to a LC-oscillator.

Hammer, Erling; Abro, Eirik; Cimpan, Emil; Yan, Guanqun

2001-02-01

234

Direct detection pays off for electron cryo-microscopy  

PubMed Central

Improved electron detectors and image-processing techniques will allow the structures of macromolecules to be determined from tens of thousands of single-particle cryo-EM images, rather than the hundreds of thousands needed previously.

2013-01-01

235

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

236

Heterogeneous post-column immunoreaction detection using magnetized beads and a laboratory-constructed electromagnetic separator.  

PubMed

The nature of immune reactors allows development of quantitative analytical methods that are highly selective and can often be used directly with complex biological matrixes such as blood, plasma or urine. A major limitation of immunoassay is that antibodies are sometimes unable to discriminate structurally similar species such as drug metabolites and synthetic analogs. The problem associated with the lack of discrimination can be circumvented by coupling immunoassay with liquid chromatography post-column. The most commonly used separation method in post-column immunoreaction detection is the affinity column. Affinity columns may create undesired effects such as a compromise of the chromatographic separation efficiency, the requirement for an antibody with fast reaction kinetics and the need for flushing the column. This paper reports a post-column immunoreaction detection system coupled with a laboratory-constructed on-line magnetic separation flow chamber that is designed to overcome these problems. The system uses disposable magnetic beads as a solid-phase support for separation that can be easily removed from the system. The model analytes chosen for this study were digoxin and its metabolites due to the commercial availability of monoclonal antibodies for these compounds. Digoxin was separated using a chromatographic method prior to being interfaced through a liquid handler system to the immunoreactor. Compatibility of the HPLC mobile phase was determined to be acceptable with a mixing ratio of 1:3 between the LC fraction and immunoreagent solution. The dynamic range of the calibration curve in digoxin-spiked phosphate buffer was found to be 0.25-12 ng/ml and a quadratic fit was found to provide the best fit to the data with a correlation coefficient of 0.9974. The residual error for all standards was less than 15%. The percentage RSDs for the two controls, 2 and 10 ng/ml, were 6.88 and 4.82% (n = 6) and the percentage errors were 7.07 and -6.89% (n = 6), respectively. PMID:12717800

Tang, Zhe; Karnes, H Thomas

2003-01-01

237

Phase separation in nematic microemulsions probed by one-dimensional spectroscopic deuteron magnetic resonance microimaging  

NASA Astrophysics Data System (ADS)

We present a study of a phase-transition-driven separation in microemulsions of nanosized lyotropic inverse micelles and thermotropic liquid crystal pentylcyanobiphenyl (5CB) with 5%, 8%, and 15% micelle concentration. Using deuteron nuclear magnetic resonance (DNMR) microimaging in combination with conventional microscopy as well as ac calorimetry, we demonstrate a phase separation scenario in which micelles are expelled from the nematic phase during the I-N conversion. Due to a difference in density the micelle-rich isotropiclike phase spatially separates from the micelle-free nematic phase. A relatively sharp interface, formed between the two phases, can be controllably shifted by temperature-induced conversion between the phases. Once expelled, micelles do not remix into the nematic phase, whereas in the isotropic state their remixing takes place over several days. Temperature dependence of the linewidth of isotropic spectral component has been analyzed in terms of molecular reorientations mediated by translational displacements, assuming isotropically distributed directors of nanosized nematic domains. With our results, the existence of the proposed transparent nematic state cannot be completely ruled out. However, if present, the nematic order in such a phase must be extremely low.

Lebar, Andrija; Kutnjak, Zdravko; Tanaka, Hajime; Zalar, Boštjan; Žumer, Slobodan

2008-09-01

238

Phase separation in nematic microemulsions probed by one-dimensional spectroscopic deuteron magnetic resonance microimaging.  

PubMed

We present a study of a phase-transition-driven separation in microemulsions of nanosized lyotropic inverse micelles and thermotropic liquid crystal pentylcyanobiphenyl (5CB) with 5%, 8%, and 15% micelle concentration. Using deuteron nuclear magnetic resonance (DNMR) microimaging in combination with conventional microscopy as well as ac calorimetry, we demonstrate a phase separation scenario in which micelles are expelled from the nematic phase during the I-N conversion. Due to a difference in density the micelle-rich isotropiclike phase spatially separates from the micelle-free nematic phase. A relatively sharp interface, formed between the two phases, can be controllably shifted by temperature-induced conversion between the phases. Once expelled, micelles do not remix into the nematic phase, whereas in the isotropic state their remixing takes place over several days. Temperature dependence of the linewidth of isotropic spectral component has been analyzed in terms of molecular reorientations mediated by translational displacements, assuming isotropically distributed directors of nanosized nematic domains. With our results, the existence of the proposed transparent nematic state cannot be completely ruled out. However, if present, the nematic order in such a phase must be extremely low. PMID:18851055

Lebar, Andrija; Kutnjak, Zdravko; Tanaka, Hajime; Zalar, Bostjan; Zumer, Slobodan

2008-09-01

239

Magnetic separation of encapsulated islet cells labeled with superparamagnetic iron oxide nano particles.  

PubMed

Islet cell transplantation is a promising option for the restoration of normal glucose homeostasis in patients with type 1 diabetes. Because graft volume is a crucial issue in islet transplantations for patients with diabetes, we evaluated a new method for increasing functional tissue yield in xenogeneic grafts of encapsulated islets. Islets were labeled with three different superparamagnetic iron oxide nano particles (SPIONs; dextran-coated SPION, siloxane-coated SPION, and heparin-coated SPION). Magnetic separation was performed to separate encapsulated islets from the empty capsules, and cell viability and function were tested. Islets labeled with 1000 ?g Fe/ml dextran-coated SPIONs experienced a 69.9% reduction in graft volume, with a 33.2% loss of islet-containing capsules. Islets labeled with 100 ?g Fe/ml heparin-coated SPIONs showed a 46.4% reduction in graft volume, with a 4.5% loss of capsules containing islets. No purification could be achieved using siloxane-coated SPIONs due to its toxicity to the primary islets. SPION labeling of islets is useful for transplant purification during islet separation as well as in vivo imaging after transplantation. Furthermore, purification of encapsulated islets can also reduce the volume of the encapsulated islets without impairing their function by removing empty capsules. PMID:23789985

Mettler, Esther; Trenkler, Anja; Feilen, Peter J; Wiegand, Frederik; Fottner, Christian; Ehrhart, Friederike; Zimmermann, Heiko; Hwang, Yong Hwa; Lee, Dong Yun; Fischer, Stefan; Schreiber, Laura M; Weber, Matthias M

2013-01-01

240

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

241

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

242

Theoretical analysis of a simple yet efficient portable magnetic separator design for separation of magnetic nano\\/micro-carriers from human blood flow  

Microsoft Academic Search

A technology that could physically remove substances from the blood such as biological, chemical, or radiological toxins could dramatically improve treatment of disease. One method in development proposes to use magnetic-polymer spheres to selectively bind toxins and remove them by magnetic filtration. Although magnetic filtration is a developed technology, the clinical boundary conditions described here require a new filter design.

Haitao Chen; Michael D. Kaminski; Armin D. Ebner; James A. Ritter; Axel J. Rosengart

2007-01-01

243

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

2013-01-01

244

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

SciTech Connect

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 magnetic properties of the solid constituents, this potentially low-cost process may serve the U.S. Department of Energy (DOE) by reducing the large quantities of glass produced from defense-related high-level waste (HLW). Furthermore, the separation of deleterious elements from low-level waste (LLW) also can reduce the total quantity of waste produced in LLW immobilization activities. Many HLW 'and LLW waste' streams at both Hanford and the Savannah River Site (SRS) include constituents deleterious to the durability of borosilicate glass and the melter many of the constituents also possess paramagnetism. For example, Fe, Cr, Ni, and other transition metals may limit the waste loading and affect the durability of the glass by forming spine1 phases at the high operating temperature used in vitrification. Some magnetic spine1 phases observed in glass formation are magnetite (Fe,O,), chromite (FeCrO,), and others [(Fe, Ni, Mg, Zn, Mn)(Al, Fe, Ti, Cr)O,] as described elsewhere [Bates-1994, Wronkiewicz-1994] Stable spine1 phases can cause segregation between the glass and the crystalline phases. As a consequence of the difference in density, the spine1 phases tend to accumulate at the bottom of the glass melter, which decreases the conductivity and melter lifetime [Sproull-1993]. Crystallization also can affect glass durability [Jantzen-1985, Turcotte- 1979, Buechele-1990] by changing the chemical composition of the matrix glass surrounding the crystals or causing stress at the glass/crystal interface. These are some of the effects that can increase leaching [Jantzen-1985]. A SRS glass that was partially crystallized to contain 10% vol. crystals composed of spinels, nepheline, and acmite phases showed minimal changes in short term leachability [Jantzen-1985, Hench-1982]. However, Jantzen et k > al. found that leaching increased preferentially at grain boundary interfaces [Jantzen-1985]. For a SRL 165 glass crystallized up to 30% vol., leachability measured by normalized boron release increased by a factor of three compared to the uncrystallized glass [Kelly-1975, Plodinec-1979]. In general, the magnitude of the crystallization effect depends highly on glass composition and cooling rate.

Nunez', L.; Kaminsky', M.D.,; Crawford, C.; Ritter, J.A.

1999-12-31

245

Wave-driven rotation and mass separation in rotating magnetic mirrors  

NASA Astrophysics Data System (ADS)

Axisymmetric mirrors are attractive for fusion because of their simplicity, high plasma pressure at a given magnetic pressure, and steady state operation. Their subclass, rotating mirrors, are particularly interesting because they have increased parallel confinement, magnetohydrodynamic stability, and a natural heating mechanism. This thesis finds and explores an unusual effect in supersonically rotating plasmas: particles are diffused by waves in both potential energy and kinetic energy. Extending the alpha channeling concept to rotating plasmas, the alpha particles may be removed at low energy through the loss cone, and the energy lost may be transferred to the radial electric field. This eliminates the need for electrodes in the mirror throat, which have presented serious technical issues in past rotating plasma devices. A high azimuthal mode number perturbation on the magnetic field is a particularly simple way to achieve the latter effect. In the rotating frame, this perturbation is seen as a wave near the alpha particle cyclotron harmonic, and can break the azimuthal symmetry and magnetic moment conservation without changing the particles total energy. The particle may exit if it reduces its kinetic energy and becomes more trapped if it gains kinetic energy, leading to a steady state current that maintains the field. Simulations of single particles in rotating mirrors show that a stationary wave can extract enough energy from alpha particles for a reactor to be self-sustaining. In the same way, rotation can be produced in non-fusion plasmas. Waves are identified to produce rotation in plasma centrifuges, which separate isotopes based on their mass difference. Finally, a new high throughput mass filter which is well suited to separating nuclear waste is presented. The new filter, the magnetic centrifugal mass filter (MCMF), has well confined output streams and less potential for nuclear proliferation than competing technologies. To assess the usefulness of the MCMF, a metric for comparing mass filters is developed. With this metric, the MCMF is compared with other mass filters such as the Ohkawa filter and the conventional plasma centrifuge.

Fetterman, Abraham J.

246

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

247

Superparamagnetic magnesium ferrite nanoadsorbent for effective arsenic (III, V) removal and easy magnetic separation.  

PubMed

By doping a proper amount of Mg(2+) (~10%) into ?-Fe2O3 during a solvent thermal process, ultrafine magnesium ferrite (Mg0.27Fe2.50O4) nanocrystallites were successfully synthesized with the assistance of in situ self-formed NaCl "cage" to confine their crystal growth. Their ultrafine size (average size of ~3.7 nm) and relatively low Mg-content conferred on them a superparamagnetic behavior with a high saturation magnetization (32.9 emu/g). The ultrafine Mg0.27Fe2.50O4 nanoadsorbent had a high specific surface area of ~438.2 m(2)/g, and demonstrated a superior arsenic removal performance on both As(III) and As(V) at near neutral pH condition. Its adsorption capacities on As(III) and As(V) were found to be no less than 127.4 mg/g and 83.2 mg/g, respectively. Its arsenic adsorption mechanism was found to follow the inner-sphere complex mechanism, and abundant hydroxyl groups on its surface played the major role in its superior arsenic adsorption performance. It could be easily separated from treated water bodies with magnetic separation, and could be easily regenerated and reused while maintaining a high arsenic removal efficiency. This novel superparamagnetic magnesium ferrite nanoadsorbent may offer a simple single step adsorption treatment option to remove arsenic contamination from water without the pre-/post-treatment requirement for current industrial practice. PMID:23726698

Tang, Wenshu; Su, Yu; Li, Qi; Gao, Shian; Shang, Jian Ku

2013-07-01

248

Removal of humic acid from aqueous solution by magnetically separable polyaniline: Adsorption behavior and mechanism.  

PubMed

Magnetically separable polyaniline (Fe3O4@SiO2-PANI) was prepared by in situ chemical polymerization of aniline on the surface of silica-coated Fe3O4 nanoparticles, and characterized by FTIR spectroscopy, powder X-ray diffraction, elemental analysis, transmission electron microscopy, vibrating sample magnetometry and X-ray photoelectron spectroscopy. Characterization results showed that Fe3O4@SiO2-PANI with amino groups of 1.78mmol/g and the average diameter of 21.6nm are superparamagnetic. Adsorption behavior of Fe3O4@SiO2-PANI nanoparticles for humic acid (HA) was investigated by batch experiments and adsorption kinetic tests. HA adsorption amount on the adsorbent decreased with increasing solution pH and the presence of Ca(2+) resulted in the enhanced HA adsorption. HA adsorption on Fe3O4@SiO2-PANI could be well described by Langmuir model and the maximum adsorption amount of the adsorbent for HA at 25°C was 36.36mg/g. HA adsorption process on the adsorbent obey pseudo-second-order kinetics and the adsorption rates decrease with increasing initial HA concentration. The XPS analysis verified that HA adsorption over the adsorbent could be attributed to the surface complexation between the disassociated HA molecules and the protonated nitrogen of polyaniline on the adsorbent. HA loaded adsorbent could be magnetically separated and easily desorbed in 0.01mol/L NaOH solution. Regeneration tests indicated that Fe3O4@SiO2-PANI could be used repeatedly. PMID:24998066

Wang, Jiahong; Bi, Lijuan; Ji, Yanfen; Ma, Hongrui; Yin, Xiaolong

2014-09-15

249

Ground validation of CryoSat-2 on Austfonna, Svalbard  

NASA Astrophysics Data System (ADS)

Backscatter measured by CryoSat-2 over land-ice surfaces is related to variability within the near surface layers. We present a suite of ground truthing data from the Austfonna ice cap, Svalbard, collected coincident with CryoSat-2 data acquisition during spring 2011. The ground based and airborne ground truthing data is used to validate interpretation of the snow surface and previous summer surface from the CryoSat-2 radar altimetry data. The ground based data consist of Ku-band and 800 MHz radar profiles, snow pits, firn cores and borehole videos. The airborne data includes Ku-band radar and laser scanner. The previous summer surface is tracked in the 800MHz radar data and used to validate retracking of this layer in the ground based Ku-band radar, airborne ASIRAS and CryoSat-2 data. Further identification of critical interfaces influencing the CryoSat-2 data are identified by down scaling the bandwidth of the airborne ASIRAS and ground based Ku-band radar data to that of CryoSat-2. A decade time series of winter snow pack and glacier facies for the Austfonna ice cap interpreted from 800 MHz ground-penetrating radar data show it to consist of firn (a wet snow zone), superimposed ice and ablation ice. There has been considerable variation in both the firn area and the firn-ice transition over this period. It remains to be seen if, in addition to the winter snow pack, we can monitor the horizontal distribution of firn with CryoSat-2.

Langley, K.; Dunse, T.; Hawley, R. L.; Patel, A. E.; Eiken, T.; Hagen, J. O.; Helm, V.; Skourup, H.

2012-12-01

250

A novel smart microsphere with magnetic core and ion-recognizable shell for pb(2+) adsorption and separation.  

PubMed

Smart core-shell microspheres for selective Pb(2+) adsorption and separation have been developed. Each microsphere is composed of a Pb(2+) recognizable poly(N-isopropylacrylamide-co-benzo-18-crown-6-acrylamide) (PNB) shell and a magnetic Fe3O4 core. The magnetic PNB core-shell microspheres show excellent Pb(2+) adsorption selectivity among the coexisting Cd(2+), Co(2+), Cr(3+), Cu(2+), Ni(2+), Zn(2+), K(+), and Ca(2+) ions by forming stable B18C6Am/Pb(2+) host-guest complexes and exhibit an interesting temperature-dependent Pb(2+) adsorption. The inner independent magnetic Fe3O4 cores enable the Pb(2+)-adsorbed microspheres with a magnetically guided aggregation to be separated from the treated solution using a remotely controlled manner. The isothermal Pb(2+) adsorption result fits well with the Freundlich isotherm. The magnetic PNB core-shell microspheres show very fast adsorption of Pb(2+), and the adsorption process of Pb(2+) onto magnetic PNB core-shell microspheres fits well with the pseudo-second-order model. Moreover, Pb(2+)-adsorbed microspheres can be regenerated by simply increasing the operation temperature and washing with deionized water. The proposed magnetic PNB core-shell microspheres provide a promising candidate for Pb(2+) adsorbents with selectively separable and efficiently reusable abilities. PMID:24897191

Liu, Ying-Mei; Ju, Xiao-Jie; Xin, Yan; Zheng, Wei-Chao; Wang, Wei; Wei, Jie; Xie, Rui; Liu, Zhuang; Chu, Liang-Yin

2014-06-25

251

Fermi surface reconstruction by dynamic magnetic fluctuations and spin-charge separation near an O(3) quantum critical point  

NASA Astrophysics Data System (ADS)

Stimulated by the small/large Fermi surface controversy in the cuprates, we consider a small number of holes injected into the bilayer antiferromagnet. The system has an O(3) quantum critical point (QCP) separating the magnetically ordered and the magnetically disordered phases. We demonstrate that nearly critical quantum magnetic fluctuations can change the Fermi surface topology and also lead to spin charge separation (SCS) in two dimensions. We demonstrate that in the physically interesting regime there is a magnetically driven Lifshitz point (LP) inside the magnetically disordered phase. At the LP the topology of the hole Fermi surface is changed. The position of the LP, while being close to the position of the QCP, generally differs. Dependent on the additional hole hopping integrals t' and t'', the LP can be located in the magnetically ordered phase and/or in the magnetically disordered phase. We also demonstrate that in this regime the hole spin and charge necessarily separate when approaching the QCP. The considered model sheds light on generic problems concerning the physics of the cuprates.

Holt, Michael; Oitmaa, Jaan; Chen, Wei; Sushkov, Oleg P.

2013-02-01

252

Coal preparation using magnetic separation. Volume 4. Evaluation of magnetic fluids for coal benefication. Final report. [Magnetic fluids are defined as dispersant-stabilized suspensions of ferromagnetic or ferrimagnetic particles in a carrier fluid  

Microsoft Academic Search

Research objectives were to acquire a body of information on the properties and potential applications of magnetic fluids, to study the selective coating behavior of magnetic fluids when contacted with a mixture of organic an inorganic matter, and to determine the extent of coal beneficiation that can be acccomplished with fluid-enhanced magnetic separation. Objectives were achieved by performing an extensive

T. A. Sladek; C. H. Cox

1980-01-01

253

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 (?-Fe 2O 3)/silica (SiO 2) composite microspheres to allow rapid magnetic separation of DNA from biological samples. With magnetite (Fe 3O 4) 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 Fe 3O 4 to ?-Fe 2O 3 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 m 2/g), and mesoporosity ( dpore=6.62 nm). The composite microsphere consists of interlocked amorphous SiO 2 nanoparticles, in which cubic ?-Fe 2O 3 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

254

Blood progenitor cell separation from clinical leukapheresis product by magnetic nanoparticle binding and magnetophoresis.  

PubMed

Positive selection of CD34+ blood progenitor cells from circulation has been reported to improve patient recovery in applications of autologous transplantation. Current magnetic separation methods rely on cell capture and release on solid supports rather than sorting from flowing suspensions, which limits the range of therapeutic applications and the process scale up. We tested CD34+ cell immunomagnetic labeling and isolation from fresh leukocyte fraction of peripheral blood (leukapheresis) using the continuous quadrupole magnetic flow sorter (QMS), consisting of a flow channel (SHOT, Greenville, IN) and a quadrupole magnet with a maximum field intensity (B(o)) of 1.42 T and a mean force field strength (S(m)) of 1.45 x 10(8) TA/m(2). Both the sample magnetophoretic mobility (m) and the inlet and outlet flow patterns highly affect the QMS performance. Seven commercial progenitor cell labeling reagent combinations were quantitatively evaluated by measuring magnetophoretic mobility of a high CD34 expression cell line, KG-1a, using the cell tracking velocimeter (CTV). The CD34 Progenitor Cell Isolation Kit (Miltenyi Biotec, Bergisch Gladbach, Germany) showed the strongest labeling of KG-1a cells and was selected for progenitor cell enrichment from 11 fresh and 11 cryopreserved clinical leukapheresis samples derived from different donors. The CD34+ cells were isolated with a purity of 60-96%, a recovery of 18-60%, an enrichment rate of 12-169, and a throughput of (1.7-9.3) x 10(4) cells/s. The results also showed a highly regular dependence of the QMS performance on the flow conditions that agreed with the theoretical predictions based on the CD34+ cell magnetophoretic mobility. PMID:17009321

Jing, Ying; Moore, Lee R; Williams, P Stephen; Chalmers, Jeffrey J; Farag, Sherif S; Bolwell, Brian; Zborowski, Maciej

2007-04-15

255

Aggregation and dispersion methods of magnetic particles, separation and detection methods using the same and detection kit  

US Patent & Trademark Office Database

It is intended to provide a method capable of simply aggregating magnetic particles having a surface modified with a thermoresponsive polymer at a given temperature without heating or cooling an aqueous solution containing the magnetic particles, and a separation method and a detection method of a substance to be detected in a sample using the method. The method of separating a substance to be detected from a sample includes the steps of: mixing an adsorbent and the sample in an aqueous solution to adsorb the substance to be detected on the adsorbent, aggregating the adsorbent by changing a salt concentration in the aqueous solution; and collecting the adsorbent from the aqueous solution by a magnetic force, wherein said adsorbent comprises a magnetic particle of an average particle size of 50 to 1000 nm, a surface of which is modified with a thermoresponsive polymer and is immobilized with a substance having an affinity for the substance to be detected.

2012-01-31

256

The Development of the CryoTel™ LT and GT  

NASA Astrophysics Data System (ADS)

This paper describes the considerations, design modifications and test results for the recently-developed Sunpower CryoTel™ LT and GT. After successful market introduction of the CryoTel™ CT, it became evident that some basic design modifications would render the unit available to a wider range of application. The CryoTel™ LT is a low-temperature variant of the original design. The LT's cooling capacity is 0.5W at 23 K. The CryoTel™ GT is the enhanced performance variant. The GT's cooling capacity is 15 W at 77 K. Both LT and GT largely retain the original structure and components and therefore benefit from the low-cost manufacturing profile of the original. Sunpower's main analysis and simulation tools were in-house codes and Gedeon Associates' SAGE Stirling cycle simulation. The CryoTel™ is a Linear Free Piston Integral Stirling cryocooler that makes use of Gas Bearing technology for non-contact operation and a microprocessor based driver/controller with a closed-loop temperature control.

Unger, Reuven

2006-04-01

257

Cryo-balloon catheter localization in fluoroscopic images  

NASA Astrophysics Data System (ADS)

Minimally invasive catheter ablation has become the preferred treatment option for atrial fibrillation. Although the standard ablation procedure involves ablation points set by radio-frequency catheters, cryo-balloon catheters have even been reported to be more advantageous in certain cases. As electro-anatomical mapping systems do not support cryo-balloon ablation procedures, X-ray guidance is needed. However, current methods to provide support for cryo-balloon catheters in fluoroscopically guided ablation procedures rely heavily on manual user interaction. To improve this, we propose a first method for automatic cryo-balloon catheter localization in fluoroscopic images based on a blob detection algorithm. Our method is evaluated on 24 clinical images from 17 patients. The method successfully detected the cryoballoon in 22 out of 24 images, yielding a success rate of 91.6 %. The successful localization achieved an accuracy of 1.00 mm +/- 0.44 mm. Even though our methods currently fails in 8.4 % of the images available, it still offers a significant improvement over manual methods. Furthermore, detecting a landmark point along the cryo-balloon catheter can be a very important step for additional post-processing operations.

Kurzendorfer, Tanja; Brost, Alexander; Jakob, Carolin; Mewes, Philip W.; Bourier, Felix; Koch, Martin; Kurzidim, Klaus; Hornegger, Joachim; Strobel, Norbert

2013-03-01

258

Preparation of magnetic molecularly imprinted polymer for the separation of tetracycline antibiotics from egg and tissue samples  

Microsoft Academic Search

Magnetic molecularly imprinted polymers were prepared using hydrophobic Fe3O4 magnetite as the magnetically susceptible component, oxytetracycline as template molecule, methacrylic acid as functional monomer, and styrene and divinylbenzene as polymeric matrix components. The polymers were applied to the separation of tetracycline antibiotics from egg and tissue samples. The extraction and clean-up procedures were carried out in a single step by

Ligang Chen; Jun Liu; Qinglei Zeng; Hui Wang; Aimin Yu; Hanqi Zhang; Lan Ding

2009-01-01

259

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

260

Magnetic cell separation for purification of human oral keratinocytes: an effective method for functional studies without prior cell subcultivation  

Microsoft Academic Search

In studying human oral keratinocytes, it would be very helpful to obtain a pure population of cells without prior in vitro\\u000a expansion. An immunomagnetic separation technique, or magnetic cell separation (MACS), was modified for efficient purification\\u000a of human oral keratinocytes. Subsequent to two-step enzymatic digestion, the cell suspension was labelled with a mouse anti-CD45\\u000a (pan-leukocyte) monoclonal antibody (MoAb) to stain

M. Formanek; A. Temmel; B. Knerer; M. Willheim; W. Millesi; J. Kornfehl

1998-01-01

261

Excitonic charge-density-wave instability of spatially separated electron-hole layers in strong magnetic fields  

Microsoft Academic Search

We use the Hartree-Fock approximation to investigate the ground state of a system consisting of spatially separated electron and hole layers in strong magnetic fields. When the layer separation is larger than a critical value a novel excitonic-density-wave state is found to have a lower energy than either a homogeneous exciton fluid or a double charge-density-wave state. The order parameters

X. M. Chen; J. J. Quinn

1991-01-01

262

CryoEDM: A cryogenic experiment to measure the neutron electric dipole moment  

NASA Astrophysics Data System (ADS)

CryoEDM is an experiment that aims to measure the electric dipole moment (EDM) of the neutron to a precision of 10 -28 e cm. A description of CryoEDM, the apparatus, technologies and commissioning is presented.

van der Grinten, M. G. D.; CryoEDM Collaboration; Balashov, S. N.; Francis, V.; Green, K.; Iaydjiev, P. S.; Ivanov, S. N.; Khazov, A.; Tucker, M. A. H.; Wark, D. L.; Davidson, A.; Hardiman, M.; Harris, P. G.; Katsika, K.; Pendlebury, J. M.; Peeters, S. J. M.; Shiers, D. B.; Smith, P.; Townsley, C.; Wardell, I.; Clarke, C.; Henry, S.; Kraus, H.; McCann, M.; Geltenbort, P.; Yoshiki, Y.

2009-12-01

263

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

264

CryoScout: A Descent Through the Mars Polar Cap  

NASA Technical Reports Server (NTRS)

CryoScout was proposed as a subsurface investigation of the stratigraphic climate record embedded in Mars North Polar cap. After landing on a gentle landscape in the midst of the mild summer season, CryoScout was to use the continuous polar sunlight to power the descent of a cryobot, a thermal probe, into the ice at a rate of about 1 m per day. CryoScout would probe deep enough into this time capsule to see the effects of planetary obliquity variations and discrete events such as dust storms or volcanic eruptions. By penetrating tens of meters of ice, the mission would explore at least one of the dominant "MOC layers" observed in exposed layered terrain.

Hecht, M. H.; Saunders, R. S.

2003-01-01

265

Fluorescence cryo-microscopy: current challenges and prospects  

PubMed Central

Studying biological structures with fine details does not only require a microscope with high resolution, but also a sample preparation process that preserves the structures in a near-native state. Live-cell imaging is restricted mostly to the field of light microscopy. For studies requiring much higher resolution, fast freezing techniques (vitrification) are successfully used to immobilize the sample in a near-native state for imaging with electron and X-ray cryo-microscopy. Fluorescence cryo-microscopy combines imaging of vitrified samples with the advantages of fluorescence labeling of biological structures. Technical considerations as well as the behavior of fluorophores at low temperatures have to be taken into account for developing or adapting super-resolution methods under cryo conditions to exploit the full potential of this technique.

Kaufmann, Rainer; Hagen, Christoph; Grunewald, Kay

2014-01-01

266

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

267

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

268

Ultrasensitive detection of deltamethrin by immune magnetic nanoparticles separation coupled with surface plasmon resonance sensor.  

PubMed

Small molecules or analytes present in trace level are difficult to be detected directly using conventional surface plasmon resonance (SPR) sensor, due to its small changes in the refractive index induced by the binding of these analytes on the sensor surface. In this paper, a new approach that combines SPR sensor technology with Fe3O4 magnetic nanoparticles (MNPs) assays is developed for directly detecting of deltamethrin in soybean. The Fe3O4 MNPs conjugated with antibodies specific to antigen serves as both labels for enhancing refractive index change due to the capture of target analyte, and "vehicles" for the rapid delivery of analyte from a sample solution to the sensor surface. Meanwhile, SPR direct detection format without Fe3O4 MNPs and gas chromatography (GC) analysis were conducted for detection of deltamethrin in soybean to demonstrate the amplification effect of Fe3O4 MNPs. A good linear relationship was obtained between SPR responses and deltamethrin concentrations over a range of 0.01-1ng/mL with the lowest measurable concentration of 0.01ng/mL. The results reveal that the detection sensitivity for deltamethrin was improved by 4 orders of magnitude compared with SPR direct detection format. The recovery of 95.5-119.8% was obtained in soybean. The excellent selectivity of the present biosensor is also confirmed by two kinds of pesticides (fenvalerate and atrazine) as controls. This magnetic separation and amplification strategy has great potential for detection of other small analytes in trace level concentration, with high selectivity and sensitivity by altering the target-analyte-capture agent labeled to the carboxyl-coated Fe3O4 MNPs. PMID:24747571

Liu, Xia; Li, Lei; Liu, You-Qian; Shi, Xing-Bo; Li, Wen-Jin; Yang, Yang; Mao, Lu-Gang

2014-09-15

269

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

270

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...

271

Separable nonlinear least squares fitting with linear bound constraints and its application in magnetic resonance spectroscopy data quantification  

Microsoft Academic Search

An application in magnetic resonance spectroscopy quantification models a signal as a linear combination of nonlinear functions. It leads to a separable nonlinear least squares fitting problem, with linear bound constraints on some variables. The variable projection (VARPRO) technique can be applied to this problem, but needs to be adapted in several respects. If only the nonlinear variables are subject

Diana M. Sima; Sabine Van Huffel

2007-01-01

272

Utility of Magnetic Cell Separation as a Molecular Sperm Preparation Technique  

PubMed Central

Assisted reproductive techniques (ART) have become the treatment of choice in many cases of infertility; however the current success rates of these procedures remain suboptimal. Programmed cell death (apoptosis) most likely contributes to failed ART and to the decrease in sperm quality after cryopreservation. There is likelihood that some sperm selected for ART will display features of apoptosis despite their normal appearance, which may be partially responsible for the low fertilization and implantation rates seen with ART. One of the features of apoptosis is the externalization of phosphatidylserine (PS) residues, which are normally present on the inner leaflet of the sperm plasma membrane. Colloidal super-paramagnetic microbeads (~50 nm in diameter) conjugated with annexin-V bind to PS are used to separate dead and apoptotic spermatozoa by magnetic cell sorting (MACS). Cells with externalized PS will bind to these microbeads, while non-apoptotic cells with intact membranes do not bind and could be used during ART. We have conducted a series of experiments to investigate if the MACS technology could be used to improve ART outcomes. Our results clearly indicate that integrating MACS as a part of sperm preparation techniques will improve semen quality and cryosurvival rates by eliminating apoptotic sperm. Non-apoptotic spermatozoa prepared by MACS display higher quality in terms of routine sperm parameters and apoptosis markers. The higher sperm quality is represented by an increased oocyte penetration potential and cryosurvival rates. Thus, the selection of non-apoptotic spermatozoa by MACS should be considered to enhance ART success rates.

Said, Tamer M.; Agarwal, Ashok; Zborowski, Maciej; Grunewald, Sonja; Glander, Hans-Juergen; Paasch, Uwe

2009-01-01

273

Chemical interferences when using high gradient magnetic separation for phosphate removal: consequences for lake restoration.  

PubMed

A promising method for lake restoration is the treatment of lake inlets through the specific adsorption of phosphate (P) on strongly magnetizable particles (Fe) and their subsequent removal using in-flow high gradient magnetic separation (HGMS) techniques. In this work, we report an extensive investigation on the chemical interferences affecting P removal efficiencies in natural waters from 20 Mediterranean ponds and reservoirs. A set of three treatments were considered based on different Fe particles/P concentration ratios. High P removal efficiencies (>80%) were found in freshwater lakes (conductivities<600 ? S cm(-1)). However, a significant reduction in P removal was observed for extremely high mineralized waters. Correlation analysis showed that major cations (Mg(2+), Na(+) and K(+)) and anions (SO(4)(2-) and Cl(-)) played an essential role in P removal efficiency. Comparison between different treatments have shown that when increasing P and Fe concentrations at the same rate or when increasing Fe concentrations for a fixed P concentration, there exist systematic reductions in the slope of the regression lines relating P removal efficiency and the concentration of different chemical variables. These results evidence a general reduction in the chemical competition between P and other ions for adsorption sites on Fe particles. Additional analyses also revealed a reduction in water color, dissolved organic carbon (DOC) and reactive silicate (Si) concentrations with the addition of Fe microparticles. PMID:21741173

de Vicente, I; Merino-Martos, A; Guerrero, F; Amores, V; de Vicente, J

2011-09-15

274

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

275

A Bayesian View on Cryo-EM Structure Determination  

PubMed Central

Three-dimensional (3D) structure determination by single-particle analysis of cryo-electron microscopy (cryo-EM) images requires many parameters to be determined from extremely noisy data. This makes the method prone to overfitting, that is, when structures describe noise rather than signal, in particular near their resolution limit where noise levels are highest. Cryo-EM structures are typically filtered using ad hoc procedures to prevent overfitting, but the tuning of arbitrary parameters may lead to subjectivity in the results. I describe a Bayesian interpretation of cryo-EM structure determination, where smoothness in the reconstructed density is imposed through a Gaussian prior in the Fourier domain. The statistical framework dictates how data and prior knowledge should be combined, so that the optimal 3D linear filter is obtained without the need for arbitrariness and objective resolution estimates may be obtained. Application to experimental data indicates that the statistical approach yields more reliable structures than existing methods and is capable of detecting smaller classes in data sets that contain multiple different structures.

Scheres, Sjors H.W.

2012-01-01

276

LNG Plant Optimization Tool CryoPro: A Joint Venture.  

National Technical Information Service (NTIS)

A base-load LNG plant is planned for the 'Snohvit' field in northern Norway. A design optimization tool, CryoPro, was developed by Statoil R&D and the Division of Refrigeration Engineering, NTH-SINTEF, to be used in concept evaluations. The conditions in ...

G. Owren E. Brendeng R. S. Heiersted A. Fredheim

1992-01-01

277

Magnetic separation: track-etched magnetic micropores for immunomagnetic isolation of pathogens (adv. Healthcare mater. 7/2014).  

PubMed

On page 1078, D. Issadore and colleagues develop a new approach for isolating pathogens from messy clinical samples. Their platform, Track Etched Magnetic MicropOre (TEMPO), uses a microporous membrane coated with a soft magnetic film, creating enormous arrays of magnetic traps which allow the advantages of microfluidics to be preserved, but is robust against clogging and capable of extremely high flow rates. PMID:25044455

Muluneh, Melaku; Shang, Wu; Issadore, David

2014-07-01

278

Boundary-value problem for a counterrotating electrical discharge in an axial magnetic field. [plasma centrifuge for isotope separation  

NASA Technical Reports Server (NTRS)

An electrical discharge between two ring electrodes embedded in the mantle of a cylindrical chamber is considered, in which the plasma in the anode and cathode regions rotates in opposite directions under the influence of an external axial magnetic field. The associated boundary-value problem for the coupled partial differential equations describing the azimuthal velocity and radial current-density fields is solved in closed form. The velocity, current density, induced magnetic induction, and electric fields are presented for typical Hartmann numbers, magnetic Reynolds numbers, and geometry parameters. The discharge is shown to produce anodic and cathodic plasma sections rotating at speeds of the order 1,000,000 cm/sec for conventional magnetic field intensities. Possible application of the magnetoactive discharge as a plasma centrifuge for isotope separation is discussed.

Hong, S. H.; Wilhelm, H. E.

1978-01-01

279

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

Microsoft Academic Search

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

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

2011-01-01

280

Innovative methodology for comprehensive utilization of iron ore tailings: part 1. The recovery of iron from iron ore tailings using magnetic separation after magnetizing roasting.  

PubMed

Iron ore tailings have become one kind of the most hazardous solid waste. In order to recycle iron in the tailings, we present a technique using magnetizing roasting process followed by magnetic separation. After analysis of chemical composition and crystalline phase, according to experimental mechanism, the effects of different parameters on recovery efficiency of iron were carried out. The optimum reaction parameters were proposed as the following: ratio of coal: iron ore tailings as 1:100, roasting at 800 degrees C for 30 min, and milling 15 min of roasted samples. With these optimum parameters, the grade of magnetic concentrate was 61.3% Fe and recovery rate of 88.2%. With this method, a great amount of iron can be reused. In addition, the microstructure and phase transformation of the process of magnetizing roasting were studied. PMID:19782467

Li, Chao; Sun, Henghu; Bai, Jing; Li, Longtu

2010-02-15

281

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

282

Fe3O4/PVIM-Ni(2+) Magnetic Composite Microspheres for Highly Specific Separation of Histidine-Rich Proteins.  

PubMed

Integration of the advantages of immobilized metal-ion affinity chromatography (IMAC) and magnetic microspheres is considered as an ideal pathway for quick and convenient separation of his-tagged proteins, but rare reports concern the natural histidine-rich proteins. In this article, a novel route was presented to fabricate magnetic microspheres composed of a high-magnetic-response magnetic supraparticle (Fe3O4) core and a Ni(2+)-immobilized cross-linked polyvinyl imidazole (PVIM) shell via reflux-precipitation polymerization. The unique as-prepared Fe3O4/PVIM-Ni(2+) microspheres possessed uniform flower-like structure, high magnetic responsiveness, abundant binding sites, and very easy synthesis process. Taking advantage of the pure PVIM-Ni(2+) interface and high Ni(2+) loading amount, the microspheres exhibited remarkable selectivity, excellent sensitivity, large enrichment capacity, and high recyclability in immobilization and separation of his-tagged recombinant proteins. More interestingly, it was found that the Fe3O4/PVIM-Ni(2+) microspheres also showed excellent performance for removal of the natural histidine-rich bovine serum albumin (BSA) from the complex real sample of fetal bovine serum due to the exposed histidine residues. Considering their multiple merits, this new type of Fe3O4/PVIM-Ni(2+) nanomaterial displays great potential in enriching low-abundant his-tagged proteins or removing high-abundant histidine-rich natural proteins for proteomic analysis. PMID:24766586

Zhang, Yuting; Li, Dian; Yu, Meng; Ma, Wanfu; Guo, Jia; Wang, Changchun

2014-06-11

283

Quantitative imaging of flux vortices in the type-II superconductor MgB2 using cryo-Lorentz transmission electron microscopy  

NASA Astrophysics Data System (ADS)

Imaging of flux vortices in high quality MgB2 single crystals has been successfully performed in a commercial field-emission gun-based transmission electron microscope. In cryo-Lorentz microscopy, the sample quality and the vortex lattice can be monitored simultaneously, allowing one to relate microscopically the surface quality and the vortex dynamics. Such a vortex motion ultimately determines the flow resistivity ?f, the knowledge of which is indispensable for practical applications such as superconducting magnets or wires for magnetic resonance imaging. The observed patterns have been analyzed and compared with other studies by cryo-Lorentz microscopy or Bitter decoration. We find that the vortex lattice arrangement depends strongly on the surface quality obtained during the specimen preparation, and tends to form a hexagonal Abrikosov lattice at a relatively low magnetic field. Stripes or gossamerlike patterns, recently suggested as potential signatures of an unconventional behavior of MgB2, were not observed.

Cottet, M. J. G.; Cantoni, M.; Mansart, B.; Alexander, D. T. L.; Hébert, C.; Zhigadlo, N. D.; Karpinski, J.; Carbone, F.

2013-07-01

284

Towards an electro-magnetic field separation of deposited material implemented in an ion beam sputter process  

SciTech Connect

Nowadays, Ion Beam Sputter (IBS) processes are very well optimized on an empirical basis. To achieve further progresses, a modification of the IBS process by guiding the coating material using an axial magnetic field and an additional electrical field has been studied. The electro-magnetic (EM) field leads to a significant change in plasma properties and deposition rate distributions, whereas an increase in deposition rate along the centerline of the axial EM field around 150% was observed. These fundamental studies on the prototype are the basis for the development of an applicable and workable design of a separation device.

Malobabic, Sina; Jupe, Marco; Ristau, Detlev [Laser Component Department, Laser Zentrum Hannover e.V., Hollerithallee 8, 30149 Hannover (Germany) [Laser Component Department, Laser Zentrum Hannover e.V., Hollerithallee 8, 30149 Hannover (Germany); Quest: Centre of Quantum Engineering and Space-Time Research, Leibniz Universitaet Hannover, Hannover (Germany)

2013-06-03

285

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

286

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

2011-08-01

287

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

288

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

Microsoft Academic Search

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-BW6 antibody was coupled to 400 nm diameter Fe3O4 containing albumin microspheres via surface-incorporated St. aureus Protein-A. The mixture of HLA-BW6 and-BW4 human peripheral blood lymphocytes was incubated

J. Kandzia; M. J. D. Anderson; W. Miiller-Ruchholtz

1981-01-01

289

Potential application of antibody-mimicking peptides identified by phage display in immuno-magnetic separation of an antigen.  

PubMed

Phage display was performed against human IgG (hIgG) through five rounds of 'biopanning'. Each round consisted of: (1) incubating a library of phage-displayed 12-mer peptides sequences on hIgG-coated magnetic beads, (2) washing the unbound phages, and (3) eluting the bound phages. The eluted phages were either amplified to enrich the pool of positive clones or subjected to the next round without amplification. Through ELISA, four clones (F9, D1, G5, and A10) showing specific binding affinity to hIgG were identified. Among these, F9 had the highest affinity (K(d)=6.2 nM), only one order of magnitude lower than the native anti-hIgG antibody (0.66 nM). Following the DNA sequences of the selected clones, four 12-mer peptides were chemically synthesized. Among them, D1 peptide showed the highest binding affinity to hIgG via SPR biosensor measurements. This peptide was conjugated to biofunctionalized magnetic beads, and its immuno-binding ability was compared with that of the native antibody immobilized to magnetic beads. The mol-to-mol binding efficacy of the peptide-coated magnetic beads was approximately 1000-fold lower than that of the antibody-coated magnetic beads. Our results suggest a feasibility of using antibody-mimicking peptides identified by phage display technique for immuno-magnetic separation of an antigen. PMID:22796092

Hien, Thai Bao Dieu; Maeng, Joon-Ho; Lee, Byung Heon; Seong, Gi Hun; Choo, Jaebum; Lee, E K

2012-10-31

290

Correlation between electrical and magnetic properties of phase-separated manganites studied with a general effective medium model  

NASA Astrophysics Data System (ADS)

We have performed electrical resistivity and DC magnetization measurements as a function of temperature, on polycrystalline samples of phase-separated La 5/8-yPr yCa 3/8MnO 3 ( y=0.3). We have used the general effective medium theory to obtain theoretical resistivity vs. temperature curves corresponding to different fixed ferromagnetic (FM) volume fraction values, assuming that the sample is a mixture of typical metallic-like and insulating manganites. By comparing this data with our experimental resistivity curves we have obtained the relative FM volume fraction of our sample as a function of temperature. This result matches with the corresponding magnetization data in excellent agreement, showing that a mixed-phase scenario is the key element to explain both the magnetic and transport properties in the present compound.

Sacanell, J.; Quintero, M.; Parisi, F.; Ghivelder, L.; Leyva, A. G.; Levy, P.

2007-09-01

291

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

292

Correspondence between neutron depolarization and higher order magnetic susceptibility to investigate ferromagnetic clusters in phase separated systems  

NASA Astrophysics Data System (ADS)

It is a tough task to distinguish a short-range ferromagnetically correlated cluster-glass phase from a canonical spin-glass-like phase in many magnetic oxide systems using conventional magnetometry measurements. As a case study, we investigate the magnetic ground state of La0.85Sr0.15CoO3, which is often debated based on phase separation issues. We report the results of two samples of La0.85Sr0.15CoO3 (S-1 and S-2) prepared under different conditions. Neutron depolarization, higher harmonic ac susceptibility and magnetic relaxation studies were carried out along with conventional magnetometry measurements to differentiate subtle changes at the microscopic level. There is no evidence of ferromagnetic correlation in the sample S-2 attributed to a spin-glass phase, and this is compounded by the lack of existence of a second order component of higher harmonic ac susceptibility and neutron depolarization. A magnetic relaxation experiment at different temperatures complements the spin glass characteristic in S-2. All these signal a sharp variance when we consider the cluster-glass-like phase (phase separated) in S-1, especially when prepared from an improper chemical synthesis process. This shows that the nonlinear ac susceptibility is a viable tool to detect ferromagnetic clusters such as those the neutron depolarization study can reveal.

Manna, Kaustuv; Samal, D.; Bera, A. K.; Elizabeth, Suja; Yusuf, S. M.; Kumar, P. S. Anil

2014-01-01

293

Correspondence between neutron depolarization and higher order magnetic susceptibility to investigate ferromagnetic clusters in phase separated systems.  

PubMed

It is a tough task to distinguish a short-range ferromagnetically correlated cluster-glass phase from a canonical spin-glass-like phase in many magnetic oxide systems using conventional magnetometry measurements. As a case study, we investigate the magnetic ground state of La0.85Sr0.15CoO3, which is often debated based on phase separation issues. We report the results of two samples of La0.85Sr0.15CoO3 (S-1 and S-2) prepared under different conditions. Neutron depolarization, higher harmonic ac susceptibility and magnetic relaxation studies were carried out along with conventional magnetometry measurements to differentiate subtle changes at the microscopic level. There is no evidence of ferromagnetic correlation in the sample S-2 attributed to a spin-glass phase, and this is compounded by the lack of existence of a second order component of higher harmonic ac susceptibility and neutron depolarization. A magnetic relaxation experiment at different temperatures complements the spin glass characteristic in S-2. All these signal a sharp variance when we consider the cluster-glass-like phase (phase separated) in S-1, especially when prepared from an improper chemical synthesis process. This shows that the nonlinear ac susceptibility is a viable tool to detect ferromagnetic clusters such as those the neutron depolarization study can reveal. PMID:24275331

Manna, Kaustuv; Samal, D; Bera, A K; Elizabeth, Suja; Yusuf, S M; Kumar, P S Anil

2014-01-01

294

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

295

Development of a cryopreservation procedure using aluminium cryo-plates.  

PubMed

A cryopreservation procedure using an aluminium cryo-plate was successfully developed using in vitro-grown Dalmatian chrysanthemum (Tanacetum cinerariifolium) shoot tips. Shoot cultures were cold-hardened at 5 degree C on MS medium containing 0.5 M sucrose over a period of 20 to 40 days. Shoot tips with basal plate (1.0-1.5 x 1.0 mm) were dissected from shoot cultures and precultured at 5 degree C for 2 days on MS medium containing 0.5 M sucrose. Precultured shoot tips were placed on aluminium cryo-plates (7 mm x 37 mm x 0.5 mm) with 10 wells (diameter 1.5 mm, depth 0.75 mm) and embedded in alginate gel. Osmoprotection was performed by immersing the cryo-plates for 30 or 60 min in 25 ml pipetting reservoirs filled with loading solution (2 M glycerol + 1.4 M sucrose). For dehydration, the loading solution was replaced with PVS 7M vitrification solution (30 percent glycerol, 19.5 percent ethylene glycol and 0.6 M sucrose in liquid MS basal medium), which was applied for 40 min. After rapid immersion in liquid nitrogen, shoot tips attached to the cryo-plates were rewarmed by immersion in cryotubes containing 2 ml 1 M sucrose solution. Using this procedure, regrowth of cryopreserved shoot tips of line 28v-75 reached 77 degree. This protocol was successfully applied to six additional lines, with high regrowth percentages ranging from 65 to 90 percent. By contrast, the modified vitrification protocol tested as a reference produced only moderate regrowth percentages. This new method displays many advantages and will facilitate large scale cryostorage in genebank. PMID:21766155

Yamamoto, Shin-ichi; Rafique, Tariq; Priyantha, Wickramage Saman; Fukui, Kuniaki; Matsumoto, Toshikazu; Niino, Takao

2011-01-01

296

Application of magnetic poly(styrene-glycidyl methacrylate) microspheres for immunomagnetic separation of bone marrow cells  

NASA Astrophysics Data System (ADS)

Surface-functionalized magnetic poly(styrene-glycidyl methacrylate) (PS-GMA) microspheres were prepared and coupled with Sca-1 antibody for cell selection from murine bone marrow mononuclear cells (MNCs). Biotinylated Sca-1 antibody could be directly coupled to avidin-bound magnetic microspheres. Alternatively, oxidized goat anti-mouse antibody was covalently bound onto the amino group-containing magnetic microspheres in a site-directed manner, and the resultant conjugate was coupled with non-modified Sca-1 antibody. Using the indirect antibody-bound magnetic microspheres, the purity of isolated Sca-1 + cells increased with bead-to-cell ratio. Using a bead-to-cell ratio of 10 beads/cell, a purity of 85% Sca-1 + cells corresponding to a 17-fold enrichment was achieved.

Chung, Ting-Hao; Chang, Jing-Yi; Lee, Wen-Chien

2009-05-01

297

Magnetically separable and recyclable urchin-like Co-P hollow nanocomposites for catalytic hydrogen generation  

NASA Astrophysics Data System (ADS)

One-pot well-controlled synthetic strategy was developed to achieve urchin-like Co-P hollow nanocomposites with tailorable magnetic properties which enable them to perform as magnetically recyclable nanocatalysts in a “quasi-homogeneous” system for the catalytic hydrogen generation via hydrolysis of Ammonia-Borane (AB). The key point of this strategy was that ferromagnetic Co nanoparticles (NPs) were embedded into paramagnetic Co2P matrix to form magnetic nanocomposites. The as-prepared Co-P NPs showed appreciable catalytic activity, recyclability and durability in hydrolysis of AB. Moreover, the chemical regeneration of AB from the “hydrolyzate” may also benefit from these magnetically recyclable catalysts. We further highlighted the excellent high-temperature resistance of Co-P NPs by calcining them at 300 °C and 600 °C. Our research may facilitate the practical application of AB as a sustainable hydrogen storage material for hydrogen-based energy.

Guo, Huizhang; Liu, Xiang; Hou, Yuhui; Xie, QingShui; Wang, Laisen; Geng, Hao; Peng, Dong-Liang

298

Meniscus-Assisted High-Efficiency Magnetic Collection and Separation for EWOD Droplet Microfluidics  

Microsoft Academic Search

This paper describes a technique to increase the efficiency of magnetic concentration on an electrowetting-on-dielectric (EWOD)-based droplet (digital) microfluidic platform operated in air, i.e., on dry surface. Key differences in the force scenario for droplet microfluidics vis-a-vis the conventional continuous microfluidic systems are identified to explain the rationale behind the proposed idea. In particular, the weakness of the magnetic force

Gaurav J. Shah

2009-01-01

299

Separation of the contributions to the magnetization of Tm1 - x Yb x B12 solid solutions in steady and pulsed magnetic fields  

NASA Astrophysics Data System (ADS)

The magnetization of substitutional Tm1 - x Yb x B12 solid solutions is studied in the composition range 0 < x ? 0.81. The measurements are performed at low temperatures (1.9-300 K) in steady (up to 11 T) and pulsed (up to 50 T, pulse duration of 20-100 ms) magnetic fields. An analysis of the experimental data allowed the contributions to the magnetization of the paramagnetic phase of the Tm1 - x Yb x B12 compounds to be separated. These contributions include a Pauli component, which corresponds to the response of the heavy-fermion manybody states that appears in the energy gap in the vicinity of the Fermi level (density of states (3-4) × 1021 cm-3 meV-1), and a contribution with saturation in high magnetic fields attributed to the localized magnetic moments ((0.8-3.7)?B per unit cell) of the nanoclusters formed by rare-earth ions with an antiferromagnetic interaction.

Bogach, A. V.; Sluchanko, N. E.; Glushkov, V. V.; Demishev, S. V.; Azarevich, A. N.; Filippov, V. B.; Shitsevalova, N. Yu.; Levchenko, A. V.; Vanacken, J.; Moshchalkov, V. V.; Gabani, S.; Flachbart, K.

2013-05-01

300

Multi-Compartment Separation in Magnetic Resonance Using Transient Steady-State Free Precession Imaging.  

National Technical Information Service (NTIS)

Disclosed is a method of quantitatively separating tissue signals based on relaxation time differences. The method uses the transient signal decay in steady-state free precession (balanced SSFP) imaging to provide an alternative to standard CPMG methods o...

B. A. Hargreaves

2003-01-01

301

In-beam spectroscopy using the JYFL gas-filled magnetic recoil separator RITU  

Microsoft Academic Search

The techniques of recoil-gating and recoil-decay tagging have been employed at Jyväskylä to perform in-beam ?-ray and electron spectroscopy studies of heavy nuclei. The JUROSPHERE ?-ray array and the SACRED electron spectrometer have been placed at the target position of the JYFL gas-filled recoil separator recoil ion transport unit (RITU). The RITU separator has been used to collect the recoils

J. Uusitalo; P. Jones; P. Greenlees; P. Rahkila; M. Leino; A. N. Andreyev; P. A. Butler; T. Enqvist; K. Eskola; T. Grahn; R.-D. Herzberg; F. Hessberger; R. Julin; S. Juutinen; A. Keenan; H. Kettunen; P. Kuusiniemi; A. P. Leppänen; P. Nieminen; R. Page; J. Pakarinen; C. Scholey

2003-01-01

302

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

2013-11-01

303

Visualization of membrane protein domains by cryo-electron microscopy of dengue virus  

Microsoft Academic Search

Improved technology for reconstructing cryo-electron microscopy (cryo-EM) images has now made it possible to determine secondary structural features of membrane proteins in enveloped viruses. The structure of mature dengue virus particles was determined to a resolution of 9.5 Å by cryo-EM and image reconstruction techniques, establishing the secondary structural disposition of the 180 envelope (E) and 180 membrane (M) proteins

Wei Zhang; Paul R Chipman; Jeroen Corver; Peter R Johnson; Ying Zhang; Suchetana Mukhopadhyay; Timothy S Baker; James H Strauss; Michael G Rossmann; Richard J Kuhn

2003-01-01

304

Preparation of magnetic molecularly imprinted polymer for the separation of tetracycline antibiotics from egg and tissue samples.  

PubMed

Magnetic molecularly imprinted polymers were prepared using hydrophobic Fe(3)O(4) magnetite as the magnetically susceptible component, oxytetracycline as template molecule, methacrylic acid as functional monomer, and styrene and divinylbenzene as polymeric matrix components. The polymers were applied to the separation of tetracycline antibiotics from egg and tissue samples. The extraction and clean-up procedures were carried out in a single step by blending and stirring the sample, extraction solvent and polymers. The analytes can be transferred from the sample matrix to the polymers directly or through the extraction solvent as medium. When the extraction was complete, the polymers adsorbing the analytes were easily separated from the sample matrix by an adscititious magnet. The analytes eluted from the polymers were determined by liquid chromatography-tandem mass spectrometry. The recoveries ranging from 72.8% to 96.5% were obtained with relative standard deviations in the range of 2.9-12.3%. The limit of detection was less than 0.2 ng g(-1). The feasibility of this method was validated by analysis of incurred egg and tissue samples, and the results were compared with those obtained by the classical method in which solvent extraction, centrifugation, and subsequent clean-up and concentration by solid-phase extraction were applied. The proposed method reduced the complicacy of classical method and improved the reliability of method. PMID:19268956

Chen, Ligang; Liu, Jun; Zeng, Qinglei; Wang, Hui; Yu, Aimin; Zhang, Hanqi; Ding, Lan

2009-05-01

305

Dehydration improves cryopreservation of mat rush (Juncus decipiens Nakai) basal stem buds on cryo-plates.  

PubMed

Two cryopreservation procedures using aluminium cryo-plates, termed V-Cryo-plate and D-Cryo-plate, were successfully developed for in vitro mat rush (Juncus decipiens Nakai) basal stem buds. Multiple stems induced in liquid MS medium containing 8.9 ?M BA by roller culture were cut into small clumps, plated on solid MS medium and cultured for 1 week at 25 degree C. Clumps that had produced many buds were cold-hardened at 5 degree C for 1-2 months. The buds with basal stems were dissected from small clumps and precultured overnight at 25 degree C on solid MS medium containing 0.3 M sucrose. Precultured buds were placed on aluminium cryo-plates and embedded in calcium alginate gel. Osmoprotection was performed by immersing the cryo-plates for 30 min at 25 degree C in loading solution (2 M glycerol + 1.0 M sucrose). In the D-Cryo-plate procedure, the buds were dehydrated to 27-25% moisture content (fresh weight) by placing the cryo-plates in the air current of a laminar flow cabinet for 2 to 3 h. In the V-Cryo-plate procedure, buds were dehydrated by immersing the cryo-plates in PVS2 vitrification solution for 40 min at 25 degree C. In both procedures, cooling was performed by placing the cryo-plates in uncapped cryotubes, which were immersed in liquid nitrogen. For rewarming, cryo-plates were immersed in medium with 1.0 M sucrose for 20 min at room temperature. Regrowth of cryopreserved buds of line 'Kitakei 2' using D-Cryo-plate and V-Cryo-plate procedures, was 90% and 80%, respectively. The two procedures were applied to 20 additional mat rush lines. Using the V-Cryo-plate procedure resulted in regrowth ranging between 13.3 and 86.7%, with an average of 52.5%. The D-Cryo-plate led to regrowth ranging between 73.3 and 96.7%, with an average of 86.3%. The D-Cryo-plate procedure will facilitate cryostorage of mat rush germplasm. PMID:24441366

Niino, T; Yamamoto, S I; Fukui, K; Castillo Martinez, C R; Arizaga, M V; Matsumoto, T; Engelmann, F

2013-01-01

306

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

2012-02-21

307

Water-compatible magnetic imprinted microspheres for rapid separation and determination of triazine herbicides in environmental water.  

PubMed

A novel kind of water-compatible magnetic imprinted cyromazine microsphere (WCMM) was synthesized by water/oil/water suspension polymerization. The obtained WCMM was homogenously spherical with porous morphology and strong magnetic properties. The microspheres were successfully used as adsorbent in dispersive solid-phase extraction (WCMM-dSPE) to selectively extract cyanazine and atrazine from environmental water. Good linearity of the two analytes was observed in the range from 2.5 to 200.0ngmL(-1). The average recoveries at three spiking levels ranged from 84.8% to 104.3% with relative standard deviations (RSD) less than 6.9%. Compared with magnetic non-imprinted particles (WCMN), the proposed WCMM adsorbent of dSPE efficiently improved the efficiency of extracting cyanazine and atrazine from environmental water samples and eliminated the effect of cyromazine leakage on the quantitative analysis of cyanazine and atrazine. The proposed WCMM-dSPE method combined the advantages of magnetic separation, molecular imprinted microspheres and dSPE. PMID:24657415

Qiao, Fengxia; Row, Kyung Ho; Wang, Mengge

2014-04-15

308

Evidence for magnetic phase separation in colossal magnetoresistance compound EuB5.99C0.01  

NASA Astrophysics Data System (ADS)

EuB5.99C0.01 is a low-carrier density ferromagnet that is believed to be intrinsically inhomogeneous due to fluctuations of carbon content. In accordance with our previous studies, electric transport of EuB5.99C0.01 close above the temperature of the bulk ferromagnetic (FM) ordering is governed by magnetic polarons. Carbon-rich regions are incompatible with FM phase and therefore they act as spacers preventing magnetic polarons to link, to form FM clusters, and eventually to percolate and establish a (homogoneous) bulk FM state in this compound, what consequently causes additional (magneto) resistance increase. Below the temperature of the bulk FM ordering, carbon-rich regions give rise to helimagnetic domains, which are responsible for an additional scattering term in the electrical resistivity. Unfortunately, there has not been provided any direct evidence for magnetic phase separation in EuB5.99C0.01 yet. Here reported results of electrical, heat capacity, Hall resistivity and small-angle neutron scattering studies bring evidence for formation of mixed magnetic structure, and provide consistent support for the previously proposed scenario of the magnetoresistance enhancement in EuB5.99C0.01.

Batko, I.; Batkova, M.; Tran, V. H.; Keiderling, U.; Filipov, V. B.

2014-07-01

309

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

310

Separate structure of two branches of sheared slab etai mode and effects of plasma rotation shear in weak magnetic shear region  

Microsoft Academic Search

The separate structure of two branches of the sheared slab etai mode near the minimum-q magnetic surface is analysed and the effects of plasma rotation shears are considered in the weak magnetic shear region. Results show that the separation condition depends on the non-monotonous q profile and the deviation of rational surface from the minimum-q surface. Furthermore, it is found

Jiquan Li; Y. Kishimoto; T. Tuda

2000-01-01

311

Method of separating dipole magnetic anomaly from geomagnetic field and application in underwater vehicle localization  

Microsoft Academic Search

Because dipole magnetic anomaly caused by ferromagnetic object or geologic structural change is mixed with geomagnetic field and difficult to calculate its magnitude, it lead to a problem for automatic underwater vehicle (AUV) localization aided by geomagnetic anomaly. To solve this issue, a novel AUV localization method introducing draft depth is put forward, where vertical position of AUV relative to

Huang Yu; Hao Yan-ling

2010-01-01

312

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

313

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

314

Vapor-liquid phase separator studies  

NASA Technical Reports Server (NTRS)

Porous plugs serve as both entropy rejection devices and phase separation components separating the vapor phase on the downstream side from liquid Helium 2 upstream. The liquid upstream is the cryo-reservoir fluid needed for equipment cooling by means of Helium 2, i.e Helium-4 below its lambda temperature in near-saturated states. The topics outlined are characteristic lengths, transport equations and plug results.

Yuan, S. W. K.; Lee, J. M.; Kim, Y. I.; Hepler, W. A.; Frederking, T. H. K.

1983-01-01

315

The function of neutrophils isolated by a magnetic antibody cell separation technique is not altered in comparison to a density gradient centrifugation method  

Microsoft Academic Search

Most comparative studies on neutrophil (PMN) isolation techniques have shown either activation or functional impairment of the cells due to the different separation processes. We have established a preparation method for PMN from human whole blood employing iron tagged, magnetizable antibodies against the cell surface antigen CD15. The aim of our study was to test whether this magnetic separation (MACS)

Stefan Zahler; Christian Kowalski; Andreas Brosig; Christian Kupatt; Bernhard F. Becker; Eckehart Gerlach

1997-01-01

316

Mass separation of a multicomponent plasma flow in a curvilinear magnetic field  

SciTech Connect

The motion of a metal plasma flow of a vacuum-arc discharge in a transportation plasma-optical system with a curvilinear magnetic field is studied experimentally and numerically. The flow position at the output of the system is shown to depend on the cathode material, which determines the mass-to-charge ratio of plasma ions. As a result, the flow with a greater ion mass-to-charge ratio moves along a trajectory with a larger radius. A similar effect is observed in the case of a multicomponent plasma flow generated by a composite cathode. The results of two-fluid MHD simulations of a plasma flow propagating in a curvilinear magnetic field agree qualitatively with the experimental data.

Papernyi, V. L.; Krasov, V. I. [Irkutsk State University (Russian Federation)

2011-11-15

317

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

Microsoft Academic Search

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

Neil Harrison

2010-01-01

318

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 DP(n) = 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

2013-09-01

319

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

320

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

321

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

322

Development of an aptamer-based impedimetric bioassay using microfluidic system and magnetic separation for protein detection.  

PubMed

An aptamer-based impedimetric bioassay using the microfluidic system and magnetic separation was developed for the sensitive and rapid detection of protein. The microfluidic impedance device was fabricated through integrating the gold interdigitated array microelectrode into a flow cell made of polydimethylsiloxane (PDMS). Aptamer modified magnetic beads were used to capture and separate the target protein, and concentrated into a suitable volume. Then the complexes were injected into the microfluidic flow cell for impedance measurement. To demonstrate the high performance of this novel detection system, thrombin was employed as the target protein. The results showed that the impedance signals at the frequency of 90kHz have a good linearity with the concentrations of thrombin in a range from 0.1nM to 10nM and the detection limit is 0.01nM. Compared with the reported impedimetric aptasensors for thrombin detection, this method possesses several advantages, such as the increasing sensitivity, improving reproducibility, reducing sample volume and assay time. All these demonstrate the proposed detection system is an alternative way to enable sensitive, rapid and specific detection of protein. PMID:24709326

Wang, Yixian; Ye, Zunzhong; Ping, Jianfeng; Jing, Shunru; Ying, Yibin

2014-09-15

323

Well-defined nanostructured surface-imprinted polymers for highly selective magnetic separation of fluoroquinolones in human urine.  

PubMed

The construction of molecularly imprinted polymers on magnetic nanoparticles gives access to smart materials with dual functions of target recognition and magnetic separation. In this study, the superparamagnetic surface-molecularly imprinted nanoparticles were prepared via surface-initiated reversible addition-fragmentation chain transfer (RAFT) polymerization using ofloxacin (OFX) as template for the separation of fluoroquinolones (FQs). Benefiting from the living/controlled nature of RAFT reaction, distinct core-shell structure was successfully constructed. The highly uniform nanoscale MIP layer was homogeneously grafted on the surface of RAFT agent TTCA modified Fe3O4@SiO2 nanoparticles, which favors the fast mass transfer and rapid binding kinetics. The target binding assays demonstrate the desirable adsorption capacity and imprinting efficiency of Fe3O4@MIP. High selectivity of Fe3O4@MIP toward FQs (ofloxacin, pefloxacin, enrofloxacin, norfloxacin, and gatifloxacin) was exhibited by competitive binding assay. The Fe3O4@MIP nanoparticles were successfully applied for the direct enrichment of five FQs from human urine. The spiked human urine samples were determined and the recoveries ranging from 83.1 to 103.1% were obtained with RSD of 0.8-8.2% (n = 3). This work provides a versatile approach for the fabrication of well-defined MIP on nanomaterials for the analysis of complicated biosystems. PMID:24853973

He, Yonghuan; Huang, Yanyan; Jin, Yulong; Liu, Xiangjun; Liu, Guoquan; Zhao, Rui

2014-06-25

324

Cryo-technical design aspects of the superconducting SIS100 quadrupole doublet modules  

NASA Astrophysics Data System (ADS)

The FAIR project was initiated to build an international accelerator and experimental facility for basic research activities in various fields of modern physics. The core component of the project will be the SIS100 heavy ion accelerator, producing heavy ion beams of uniquely high intensities and qualities. The superconducting main quadrupoles and corrector magnets are assembled within complex quadrupole doublet modules (QDMs), combining two superconducting quadrupole (focusing and defocusing), sextupole and steering magnets in one cryostat. In addition a cryo-catcher, a beam position monitor and a cold beam pipe will be integrated. In accordance with the magnet lattice structure, the QDM series for the SIS100 consists of four main families composed of eleven different configurations. The common technical feature of all configurations is a sophisticated common girder structure, mechanically integrating all functional components in one cold mass and being suspended in a corresponding cryostat system. The requirements to position preservation during thermal cycling are to be fulfilled by a precise and stable support of the functional elements, as well as by a reliable, reproducible and stable cold mass suspension system. The main design aspects of the QDMs will be discussed as a result of these requirements.

Meier, J. P.; Bleile, A.; Fischer, E.; Hess, G.; Macavei, J.; Spiller, P.

2014-01-01

325

Cryo-SEM of hydrated high temperature proton exchange membranes  

SciTech Connect

Alternative energy technologies, such as high temperature fuel cells and hydrogen pumps, rely on proton exchange membranes (PEM). A chemically and thermally stable PEM with rapid proton transport is sol-gel phosphoric acid (PA)-doped polybenzimidazole (PBI) membranes. It is believed that the key to the high ionic conductivity of PA-doped PBI membranes is related to the gel morphology. However, the gel structure and general morphology of this PA-doped PBI membrane has not been widely investigated. In an effort to understand the gel morphology, two SEM sample preparation methodologies have been developed for PA-doped PBI membranes. Due to the high vacuum environment of conventional SEM, the beam-sensitivity of these membranes was reduced with a mild 120 C heat treatment to remove excess water without structural rearrangement (as verified from wide angle X-ray scattering). Cryo-SEM has also been implemented for both initial and heated membranes. Cryo-SEM is known to prevent dehydration of the specimen and reduce beam-sensitivity. The SEM cross-section image (Fig. 1A) of the heated samples exhibit 3{micro}m spheroidal features that are elongated in the direction of the casting blade. These features are distorted to 2{micro}m under conventional SEM conditions (Fig. 1B). The fine-scale gel morphology image (Fig. 2) is composed of 65nm diameter domains and 30nm walls, which resembles a cellular structure. In the future, the PA-doped PBI membranes will be cryo-microtomed and cryotransferred for elemental analysis in a TEM.

Perry, Kelly A [ORNL; More, Karren Leslie [ORNL; Walker, Larry R [ORNL; Benicewicz, Brian [ORNL

2009-01-01

326

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

327

High-precision correlative fluorescence and electron cryo microscopy using two independent alignment markers.  

PubMed

Correlative light and electron microscopy (CLEM) is an emerging technique which combines functional information provided by fluorescence microscopy (FM) with the high-resolution structural information of electron microscopy (EM). So far, correlative cryo microscopy of frozen-hydrated samples has not reached better than micrometre range accuracy. Here, a method is presented that enables the correlation between fluorescently tagged proteins and electron cryo tomography (cryoET) data with nanometre range precision. Specifically, thin areas of vitrified whole cells are examined by correlative fluorescence cryo microscopy (cryoFM) and cryoET. Novel aspects of the presented cryoCLEM workflow not only include the implementation of two independent electron dense fluorescent markers to improve the precision of the alignment, but also the ability of obtaining an estimate of the correlation accuracy for each individual object of interest. The correlative workflow from plunge-freezing to cryoET is detailed step-by-step for the example of locating fluorescence-labelled adenovirus particles trafficking inside a cell. PMID:24262358

Schellenberger, Pascale; Kaufmann, Rainer; Siebert, C Alistair; Hagen, Christoph; Wodrich, Harald; Grünewald, Kay

2014-08-01

328

The baking process of wheat rolls followed by cryo scanning electron microscopy  

Microsoft Academic Search

The evolution that the microstructure of the main components of wheat flour undergoes during the bread-making process was analysed by cryo scanning electron microscopy (cryo-SEM). The microstructure of wheat flour preserved some characteristics of the intact endosperm and consisted of aggregates of protein in which were embedded groups of cellular components. At the mixing stage, the dough appeared as a

J. A. Rojas; C. M. Rosell; C. Benedito de Barber; I. Pérez-Munuera; M. A. Lluch

2000-01-01

329

High-precision correlative fluorescence and electron cryo microscopy using two independent alignment markers?  

PubMed Central

Correlative light and electron microscopy (CLEM) is an emerging technique which combines functional information provided by fluorescence microscopy (FM) with the high-resolution structural information of electron microscopy (EM). So far, correlative cryo microscopy of frozen-hydrated samples has not reached better than micrometre range accuracy. Here, a method is presented that enables the correlation between fluorescently tagged proteins and electron cryo tomography (cryoET) data with nanometre range precision. Specifically, thin areas of vitrified whole cells are examined by correlative fluorescence cryo microscopy (cryoFM) and cryoET. Novel aspects of the presented cryoCLEM workflow not only include the implementation of two independent electron dense fluorescent markers to improve the precision of the alignment, but also the ability of obtaining an estimate of the correlation accuracy for each individual object of interest. The correlative workflow from plunge-freezing to cryoET is detailed step-by-step for the example of locating fluorescence-labelled adenovirus particles trafficking inside a cell.

Schellenberger, Pascale; Kaufmann, Rainer; Siebert, C. Alistair; Hagen, Christoph; Wodrich, Harald; Grunewald, Kay

2014-01-01

330

Rapid Removal and Separation of Iron(II) and Manganese(II) from Micropolluted Water Using Magnetic Graphene Oxide.  

PubMed

A novel two-dimensional carbon-based magnetic nanomaterial, magnetic graphene oxide (MGO), was prepared and then used as an efficient adsorbent. MGO showed rapid and complete removal of iron(II) (Fe) and manganese(II) (Mn) from micropolluted water bodies over a wide pH range. After saturated adsorption, MGO could be rapidly separated from water under an external magnetic field. Results of the adsorption equilibrium study indicated that the adsorption of Fe and Mn by MGO took place via monolayer heterogeneous and spontaneous processes resulting from the heterogeneity of the MGO surface as well as from the electrostatic interactions between surface acidic groups of MGO and metal ions. In addition, both the Fe and Mn uptake of MGO was very slightly affected by NaCl, although it decreased with increased humic acid in solutions. In an Fe/Mn binary aqueous system, both metal ions can be efficiently removed at low concentrations, but MGO showed preferential adsorption of Fe in a concentrated aqueous mixture. The adsorption behavior in the binary system was due to different affinities of surface oxygen-containing functional groups on MGO to Fe and Mn. Finally, unlike traditional approaches in recycling and reusing an adsorbent, the Fe- and Mn-loaded MGO can be directly applied as a new adsorbent to achieve the efficient removal of fluoride from aqueous solutions. PMID:24787443

Yan, Han; Li, Haijiang; Tao, Xue; Li, Kun; Yang, Hu; Li, Aimin; Xiao, Shoujun; Cheng, Rongshi

2014-06-25

331

Polarization separated Zeeman spectra from magnetic dipole transitions in highly charged argon in the large helical device  

SciTech Connect

Visible spectral emission lines from magnetic dipole transitions in Ar X, Ar XI, Ar XIV, and Ar XV are observed from plasmas heated with neutral-beam injection (NBI) in the Large Helical Device [O. Motojima et al., Phys. Plasmas 6, 1843 (1999)]. Orthogonal linearly polarized components of the emission line profiles are observed with a polarization separation optical system and high-resolution spectrometer. Zeeman split profiles reveal polarization characteristics of magnetic dipole transitions. Ion temperatures and emission locations are estimated from the profiles with the magnetic field information on the lines of sight (LOS). The spatially resolved emissions are observed by the array of absolutely calibrated views. The time histories of line profiles and emission intensities at the poloidal view are presented. The observed line profiles and the intensity distribution at the poloidal view indicate the localization of these charge states in the edge region just inside the last closed flux surface. The emission line of Ar X in the tangential observation indicates Doppler shifts of the Zeeman split profiles. The velocity components of Ar X ion flow along the LOS at the tangential view are 7.7 and 2.0 km/s at the outer and inner edge plasmas, respectively, in the opposite direction to the NBI.

Iwamae, A.; Atake, M.; Sakaue, A.; Katai, R.; Goto, M.; Morita, S. [Department of Mechanical Engineering and Science, Graduate School of Engineering, Kyoto University, Kyoto, 606-8501 (Japan); Department of Fusion Science, Graduate University for Advanced Studies, Toki, 509-5292 (Japan); National Institute for Fusion Science, Toki, 509-5292 (Japan)

2007-04-15

332

Greek "red mud" residue: a study of microwave reductive roasting followed by magnetic separation for a metallic iron recovery process.  

PubMed

The present research work is focused on the development of an alternative microwave reductive roasting process of red mud using lignite (30.15 wt.%Cfix), followed by wet magnetic separation, in order to produce a raw material suitable for sponge or cast iron production. The reduction degree of iron was controlled by both the reductive agent content and the microwave heating time. The reduction followed the Fe?O? ? Fe?O? ? FeO ? Fe sequence. The dielectric constants [real (?') and imaginary (??) permittivities] of red mud-lignite mixture were determined at 2.45 GHz, in the temperature range of 25-1100 °C. The effect of parameters such as temperature, intensity of reducing conditions, intensity of magnetic field and dispersing agent addition rate on the result of both processes was investigated. The phase's transformations in reduction process with microwave heating were determined by X-ray diffraction analysis (XRD) in combination with thermogravimetric/differential thermal analysis (TGA/DTA). The microstructural and morphological characterization of the produced calcines was carried out by scanning electron microscopy (SEM). At the optimum conditions a magnetic concentrate with total iron concentration of 35.15 and 69.3 wt.% metallization degree was obtained. PMID:23611801

Samouhos, Michail; Taxiarchou, Maria; Tsakiridis, Petros E; Potiriadis, Konstantinos

2013-06-15

333

Process for decontaminating radioactive waste water using a ferrofluid and magnetic separation  

SciTech Connect

The present invention provides a process for decontaminating radioactive waste water containing a radioactive element that forms a water-insoluble compound. This process includes the steps of forming the compound of the radioactive element, treating the resulting waste water with a ferrofluid, dispersing the ferrofluid, diluting the solids concentration of the resulting mixture with a coagulation initiator, such as ethyl alcohol or acetone, and collecting by use of a magnetic field, the resulting radioactive sludge. In a variation of the process, the steps involving the use of the coagulation initiator and the use of the ferrofluid are reversed.

Silver, G.L.

1980-07-31

334

Design of Countercurrent Separation of Ginkgo biloba Terpene Lactones by Nuclear Magnetic Resonance  

PubMed Central

Terpene lactones such as bilobalide, ginkgolides A, B, C, and J are major bioactive compounds of Ginkgo biloba L. Purification of these compounds is tedious due to their similar chemical properties. For the purpose of developing an effective and efficient method for both analytical and preparative separation of terpene lactones in G. biloba, an innovative orthogonality-enhanced high-speed countercurrent chromatography (HSCCC) method was established. Taking advantage of quantitative 1H NMR (qHNMR) methodology, partition coefficients (K) of individual terpene lactones were calculated directly from crude G. biloba leaf extract, using their H-12 signals as distinguishing feature. The partitioning experiment assisted the design of a two dimensional (2D) HSCCC procedure using a pair of orthogonal HSCCC solvent systems (SSs), ChMWat +4 and HEMSoWat +3/0.05%. It was surprising that the resolution of ginkgolides A and B was improved by 25% in the HEMWat +3 SS modified with 0.5% DMSO. Consequently, all five terpene lactones could be well separated with qHNMR purity > 95% from G. biloba leaf extract. The separation was further evaluated by offline qHNMR analysis of HSCCC fractions associated with Gaussian curve fitting. The results showed less than 2% error in HSCCC retention predicted from the partitioning experiment. This compelling consistency demonstrates that qHNMR-derived K determination (“K-by-NMR”) can be used to predict CCC fractionation and target purification of analytes from complex mixtures. Furthermore, Gaussian curve fitting enabled an accurate prediction of less than 2% impurity in the CCC fraction, which demonstrates its potential as a powerful tool to study the presence of minor constituents, especially when they are beyond the detection limit of conventional spectroscopic detectors.

Qiu, Feng; Friesen, Brent J.; McAlpine, James B.; Pauli, Guido F.

2012-01-01

335

Nitrogen Separation and Liquefaction Apparatus for Medical Applications and Its Thermodynamic Optimization  

Microsoft Academic Search

Low temperature medicine is becoming a widely appreciated method in surgery, dermatology, gynecology and rheumatology. The cryomedical equipment is usually supplied with liquid nitrogen LN2 stored in a dewar and transferred to a tip, where it is evaporated providing a cooling power. LN2 in quantities sufficient for cryo-surgical and cryo-therapeutical applications can be first separated from air and then liquefied

M. Chorowski; A. Piotrowska; J. Polinski

2006-01-01

336

Three dimensional structure of the anthrax toxin translocon-lethal factor complex by cryo-electron microscopy  

PubMed Central

We have visualized by cryo-electron microscopy (cryo-EM) the complex of the anthrax protective antigen (PA) translocon and the N-terminal domain of anthrax lethal factor (LFN) inserted into a nanodisc model lipid bilayer. We have determined the structure of this complex at a nominal resolution of 16 Å by single-particle analysis and three-dimensional reconstruction. Consistent with our previous analysis of negatively stained unliganded PA, the translocon comprises a globular structure (cap) separated from the nanodisc bilayer by a narrow stalk that terminates in a transmembrane channel (incompletely distinguished in this reconstruction). The globular cap is larger than the unliganded PA pore, probably due to distortions introduced in the previous negatively stained structures. The cap exhibits larger, more distinct radial protrusions, previously identified with PA domain three, fitted by elements of the NMFF PA prepore crystal structure. The presence of LFN, though not distinguished due to the seven-fold averaging used in the reconstruction, contributes to the distinct protrusions on the cap rim volume distal to the membrane. Furthermore, the lumen of the cap region is less resolved than the unliganded negatively stained PA, due to the low contrast obtained in our images of this specimen. Presence of the LFN extended helix and N terminal unstructured regions may also contribute to this additional internal density within the interior of the cap. Initial NMFF fitting of the cryoEM-defined PA pore cap region positions the Phe clamp region of the PA pore translocon directly above an internal vestibule, consistent with its role in toxin translocation.

Gogol, E P; Akkaladevi, N; Szerszen, L; Mukherjee, S; Chollet-Hinton, L; Katayama, H; Pentelute, B L; Collier, R J; Fisher, M T

2013-01-01

337

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

338

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

339

Phase-separated alloys for bulk exchange-biased permanent magnets  

NASA Astrophysics Data System (ADS)

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 (Fe65Co35)100-x(AuMn)x (x=5, 10, and 15) was carried out. The ribbons possess AuMn and Au2Mn 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.

2006-04-01

340

Complex magnetic phase separation induced by Li-doping in multiferroic CaBaCo4O7  

NASA Astrophysics Data System (ADS)

The doping of lithium at the cobalt sites in the multiferroic orthorhombic cobaltite CaBaCo4O7 has been investigated. The oxides CaBaCo4-2xLixGaxO7 and CaBaCo4-xLixO7 keep the same polar space group as the parent phase. In contrast, they show a spectacular decrease of their ferrimagnetic properties for very low doping levels (0 < x <= 0.10), with the appearance of antiferromagnetism below TN ~ 80 K and magnetic frustration at around Tf ~ 20 K, which should have a great impact upon multiferroism in this system. This behavior is different from that of the Ga-doped phases CaBaCo4-xGaxO7, but remarkably similar to that of the Zn-doped phases CaBaCo4-xZnxO7. The actual role of the valence of the diamagnetic cation, Li+ is interpreted from its ability to sit in the Co2+ zig-zag chain, breaking the ferromagnetism along those chains in both series of oxides. Importantly, the Li-doping in CaBaCo4-xLixO7 oxides, introduces an excess Co3+ with respect to the other two series, CaBaCo4-xZnxO7 and CaBaCo4-2xLixGaxO7. This additional Co3+ is thought to be at the origin of the complex magnetic phase separation and especially of new magnetic interactions that appear around 52 K in competition with magnetic frustration and antiferromagnetism.

Motin Seikh, Md.; Sarkar, Tapati; Pralong, V.; Caignaert, V.; Raveau, B.

2013-02-01

341

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

342

Structure of Halothiobacillus neapolitanus carboxysomes by cryo-electron tomography.  

PubMed

Carboxysomes are polyhedral bodies consisting of a proteinaceous shell filled with ribulose 1,5-bisphosphate carboxylase/oxygenase (RuBisCO). They are found in the cytoplasm of all cyanobacteria and some chemoautotrophic bacteria. Previous studies of Halothiobacillus neapolitanus and Nitrobacter agilis carboxysomes suggest that the structures are either icosahedral or dodecahedral. To determine the protein shell structure more definitively, purified H. neapolitanus carboxysomes were re-examined by cryo-electron tomography and scanning transmission electron microscopy (STEM). Due to the limited tilt angles in the electron microscope, the tomographic reconstructions are distorted. Corrections were made in the 3D orientation searching and averaging of the computationally extracted carboxysomes to minimize the missing data effects. It was found that H. neapolitanus carboxysomes vary widely in size and mass as shown by cryo-electron tomography and STEM mass measurements, respectively. We have aligned and averaged carboxysomes in several size classes from the 3D tomographic reconstruction by methods that are not model-biased. The averages reveal icosahedral symmetry of the shell, but not of the density inside it, for all the size classes. PMID:17028023

Schmid, Michael F; Paredes, Angel M; Khant, Htet A; Soyer, Ferda; Aldrich, Henry C; Chiu, Wah; Shively, Jessup M

2006-12-01

343

Assessment of Lead Discrimination from CryoSat-2  

NASA Astrophysics Data System (ADS)

Sea ice is strongly affecting the global climate, and the sea ice extent has been monitored by satellites since 1979. To estimate the Arctic sea ice volume, ice thickness must be determined. The measurements of sea ice thickness are however more difficult to achieve, and encounter limitations due to spatial and temporal variability. The measurements of sea ice freeboard may be used to estimate sea ice thickness, when combined with examination of leads between ice floes to determine the local sea surface height. With CryoSat-2 (CS), we have the opportunity to measure much more of the Arctic Ocean due to its high sampling rate and geographical coverage to 88 oN/S. Validation of the CS retrievals are very important to verify the derived sea ice thickness and understand the associated error sources. We present a comparative analysis of CryoSat-2 elevations with the Operation IceBridge Airborne Topographic Mapper (ATM) laser altimeter data gathered on April 2, 2012, where the NASA P-3 completed an underflight of CS orbit number 10520, north of Alert, Nunavut, Canada. We present a new lead detecting algorithm which was developed using the CS Level1b (L1b) waveforms, and we analyze its capabilities via comparisons with IceBridge imagery and ATM elevations. In addition,using CS L1b waveforms we have developed a method to find misplaced CS Level 2 elevations and correct them to remove any elevation bias.

Rose, S. K.; Connor, L. N.; Newman, T.; Farrell, S. L.; Smith, W. H.; Forsberg, R.

2012-12-01

344

Local CP-violation and electric charge separation by magnetic fields from lattice QCD  

NASA Astrophysics Data System (ADS)

We study local CP-violation on the lattice by measuring the local correlation between the topological charge density and the electric dipole moment of quarks, induced by a constant external magnetic field. This correlator is found to increase linearly with the external field, with the coefficient of proportionality depending only weakly on temperature. Results are obtained on lattices with various spacings, and are extrapolated to the continuum limit after the renormalization of the observables is carried out. This renormalization utilizes the gradient flow for the quark and gluon fields. Our findings suggest that the strength of local CP-violation in QCD with physical quark masses is about an order of magnitude smaller than a model prediction based on nearly massless quarks in domains of constant gluon backgrounds with topological charge. We also show numerical evidence that the observed local CP-violation correlates with spatially extended electric dipole structures in the QCD vacuum.

Bali, G. S.; Bruckmann, F.; Endr?di, G.; Fodor, Z.; Katz, S. D.; Schäfer, A.

2014-04-01

345

Magnetic Separation for the Direct Observation of Mineral-Associated Microbial Diversity  

NASA Astrophysics Data System (ADS)

Previous studies have demonstrated that microorganisms may selectively colonize mineral surfaces in diverse environments. Mineral substrates may serve as an important source of limiting nutrients or provide electron acceptors and donors for dissimilatory reactions. This work presents a new method for characterizing the microbial diversity associated with specific components in environmental samples. Minerals are concentrated from the bulk sample according to magnetic susceptibility, resulting in compositionally distinct partitions. The microbial communities associated with these partitions are subsequently characterized using molecular techniques. Initial testing of samples from active and dormant hydrothermal chimney structures from the Lau and Fiji Basins show that mineral components may be concentrated from bulk samples without concealing pre-existing patterns of selective colonization. 16S gene surveys from environmental clone libraries reveal distinct colonization patterns for thermophilic archaea and bacteria between sulfide mineral partitions. This method offers a unique tool discerning the role of mineral composition in surface-associated diversity.

Harrison, B. K.; Orphan, V.

2006-12-01

346

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

347

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

NASA Technical Reports Server (NTRS)

Chromospheric fibrils are generally thought to trace out low-lying, mainly horizontal magnetic elds that fan out from flux concentrations in the photosphere. A high-resolution (approximately 0.1" per pixel) image, taken in the core of the Ca II 854.2 nm line and covering an unusually large area, shows the dark brils 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 lament channel (large-scale polarity inversion), we find that the total amount of positive-polarity flux underlying this "fibril arcade" is approximately 50 times greater than the total amount of negative-polarity flux. Thus, if the brils 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.

Reardom, K. P.; Wang, Y.-M.; Muglach, K.; Warren, H. P.

2011-01-01

348

Serum peptidome patterns of hepatocellular carcinoma based on magnetic bead separation and mass spectrometry analysis  

PubMed Central

Background Hepatocellular carcinoma (HCC) is one of the most common cancers in the world,and the identification of biomarkers for the early detection is a relevant target. The purpose of the study is to discover specific low molecular weight (LMW) serum peptidome biomarkers and establish a diagnostic pattern for HCC. Methods We undertook this pilot study using a combined application of magnetic beads with Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) technique and ClinPro Tools v2.2 to detect 32 patients with HCC, 16 patients with chronic hepatitis (CH), 16 patients with liver cirrhosis (LC) and 16 healthy volunteers. Results The results showed 49, 33 and 37 differential peptide peaks respectively appeared in HCC, LC and CH groups. A Supervised Neural Network (SNN) algorithm was used to set up the classification model. Eleven of the identified peaks at m/z 5247.62, 7637.05, 1450.87, 4054.21, 1073.37, 3883.64, 5064.37, 4644.96, 5805.51, 1866.47 and 6579.6 were used to construct the peptides patterns. According to the model, we could clearly distinguish between HCC patients and healthy controls as well as between LC or CH patients and healthy controls. Conclusions The study demonstrated that a combined application of magnetic beads with MALDI-TOF MB technique was suitable for identification of potential serum biomarkers for HCC and it is a promising way to establish a diagnostic pattern. Virtual slides The virtual slide(s) for this article can be found here: http://www.diagnosticpathology.diagnomx.eu/vs/1503629821958720.

2013-01-01

349

Levitation Performance of Two Opposed Permanent Magnet Pole-Pair Separated Conical Bearingless Motors  

NASA Technical Reports Server (NTRS)

In standard motor applications, rotor suspension with traditional mechanical bearings represents the most economical solution. However, in certain high performance applications, rotor suspension without contacting bearings is either required or highly beneficial. Examples include applications requiring very high speed or extreme environment operation, or with limited access for maintenance. This paper expands upon a novel bearingless motor concept, in which two motors with opposing conical air-gaps are used to achieve full five-axis levitation and rotation of the rotor. Force in this motor is created by deliberately leaving the motor s pole-pairs unconnected, which allows the creation of different d-axis flux in each pole pair. This flux imbalance is used to create lateral force. This approach is different than previous bearingless motor designs, which require separate windings for levitation and rotation. This paper examines the predicted and achieved suspension performance of a fully levitated prototype bearingless system.

Kascak, Peter; Jansen, Ralph; Dever, Timothy; Nagorny, Aleksandr; Loparo, Kenneth

2013-01-01

350

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

351

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

2012-02-01

352

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

NASA Astrophysics Data System (ADS)

The pressure dependence of the Curie temperature TC(P) in La0.75Ca0.25MnO3 was determined by neutron diffraction up to 8 GPa, and compared with the metallization temperature TIM(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.

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

2012-02-01

353

Hybrid magnetic field formulation based on the losses separation method for modified dynamic inverse Jiles-Atherton model  

NASA Astrophysics Data System (ADS)

Dynamic formulation based on the losses separation method in conducting media for the inverse Jiles-Atherton model is proposed. This formulation is based on the concept of the Hybrid Magnetic Field model (HMF). The HMF consists of the modification of the effective field by introducing two counter-fields associated, respectively, with the eddy current and excess losses. Such a formulation is characterized by seven parameters with five parameters issued from the quasi-static Jiles-Atherton model. Thus, two new parameters related to these fields are added to that defined in the quasi-static model. The identification of these new parameters is based on the measurements of the volumetric energy density. To validate this formulation, measurements are carried out on grain non-oriented Fe-Si 3% electrical sheets.

Hamimid, M.; Mimoune, S. M.; Feliachi, M.

2011-07-01

354

Transcranial magnetic stimulation in different current directions activates separate cortical circuits.  

PubMed

Transcranial magnetic stimulation (TMS) to the primary motor cortex (M1) produces a series of corticospinal descending waves, with a direct (D) wave followed by several indirect (I) waves. TMS inducing posterior-anterior (PA) current in the brain predominantly recruits the early I1-wave, whereas anterior-posterior (AP) directed current preferentially recruits the late I3-wave. However, it is not known whether I-waves elicited by different current directions are mediated by the same neuronal populations. We studied the neuronal mechanisms mediating I-waves by examining the influence of short-latency afferent inhibition (SAI) on various I-waves. SAI was tested with electrical median nerve stimulation at the wrist followed by TMS to the contralateral M1 at different current directions. Surface electromyograms and single motor units were recorded from the first dorsal interosseous muscle. SAI was weaker for the AP compared with that for the PA current direction. With increasing median nerve stimulation intensities, SAI increased for the PA direction but showed a U-shaped relationship for the AP direction. SAI produced more inhibition of late I-waves generated by PA than those generated by AP current direction. We conclude that late I-waves generated by PA and AP current directions are mediated by different neuronal mechanisms. PMID:21148098

Ni, Zhen; Charab, Samer; Gunraj, Carolyn; Nelson, Aimee J; Udupa, Kaviraja; Yeh, I-Jin; Chen, Robert

2011-02-01

355

Cryo-soft X-ray tomography: a journey into the world of the native-state cell.  

PubMed

One of the ultimate aims of imaging in biology is to achieve molecular localisation in the context of the structure of cells in their native state. Here, we review the current state of the art in cryo-soft X-ray tomography (cryo-SXT), which is the only imaging modality that can provide nanoscale 3D information from cryo-preserved, unstained, whole cells thicker than 1 ?m. Correlative cryo-fluorescence and cryo-SXT adds functional information to structure, enabling studies of cellular events that cannot be captured using light, electron or X-ray microscopes alone. PMID:24264466

Carzaniga, Raffaella; Domart, Marie-Charlotte; Collinson, Lucy M; Duke, Elizabeth

2014-03-01

356

Recovery of iron from high phosphorus oolitic iron ore using coal-based reduction followed by magnetic separation  

NASA Astrophysics Data System (ADS)

Oolitic iron ore is one of the most important iron resources. This paper reports the recovery of iron from high phosphorus oolitic iron ore using coal-based reduction and magnetic separation. The influences of reduction temperature, reduction time, C/O mole ratio, and CaO content on the metallization degree and iron recovery were investigated in detail. Experimental results show that reduced products with the metallization degree of 95.82% could be produced under the optimal conditions (i.e., reduction temperature, 1250°C; reduction time, 50 min; C/O mole ratio, 2.0; and CaO content, 10wt%). The magnetic concentrate containing 89.63wt% Fe with the iron recovery of 96.21% was obtained. According to the mineralogical and morphologic analysis, the iron minerals had been reduced and iron was mainly enriched into the metallic iron phase embedded in the slag matrix in the form of spherical particles. Apatite was also reduced to phosphorus, which partially migrated into the metallic iron phase.

Sun, Yong-sheng; Han, Yue-xin; Gao, Peng; Wang, Ze-hong; Ren, Duo-zhen

2013-05-01

357

Separation and purification of Si from solidification of hypereutectic Al-Si melt under rotating magnetic field  

NASA Astrophysics Data System (ADS)

A low-cost and high-efficiency method to purify Si directly from cheap MG-Si at low temperature was proposed and demonstrated in this paper, which used power frequency rotating magnetic field (RMF) to separate the primary Si from a hypereutectic Al-Si alloy and was followed by the acid peeling. The separation mechanism was based on the flow characteristic of melt under RMF and the cooling condition of the liquid metal. A Si-rich layer with Si content of 65-59 wt% was formed in the periphery of alloy, while the inner microstructure of the alloy was mainly the Al-Si eutectic structure. The refined silicon was collected after aqua regia leaching, and had much fewer typical impurities (Fe, Ti, Ca, B, P) than those in MG-Si, and the metallic impurities besides Al had removal fraction higher than 98%, which is mainly ascribed to the segregation effect of Al-30Si alloy during solidification under RMF.

Jie, J. C.; Zou, Q. C.; Wang, H. W.; Sun, J. L.; Lu, Y. P.; Wang, T. M.; Li, T. J.

2014-08-01

358

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

NASA Technical Reports Server (NTRS)

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 IJ854.2 nm line shows the dark fibrils within an active region remnant as fine, loop-like features that are aligned parallel to each other and have lengths on the order of a supergranular diameter (approx.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, K.; Reardon, K. P.; Wang, Y.-M.; Warren, H. P.

2012-01-01

359

Microchannel liquid-flow focusing and cryo-polymerization preparation of supermacroporous cryogel beads for bioseparation.  

PubMed

Polymeric cryogels are sponge-like materials with supermacroporous structure, allowing them to be of interest as new chromatographic supports, cell scaffolds and drug carriers in biological and biomedical areas. The matrices of cryogels are always prepared in the form of monoliths by cryo-polymerization under frozen conditions. However, there are limited investigations on the production of cryogels in the form of adsorbent beads suitable for bioseparation. In this work, we provide a new approach by combining the microchannel liquid-flow focusing with cryo-polymerization for the preparation of polyacrylamide-based supermacroporous cryogel beads with a narrow particle size distribution. The present method was achieved by introducing the aqueous phase solution containing monomer, cross-linker and redox initiators, and the water-immiscible organic oil phase containing surfactant simultaneously into a microchannel with a cross-shaped junction, where the aqueous drops with uniform sizes were generated by the liquid shearing and the segmentation due to the steady flow focusing of the immiscible phase streams. These liquid drops were in situ suspended into the freezing bulk oil phase for cryo-polymerization and the cryogel matrix beads were obtained by thawing after the achievement of polymerization. By grafting the polymer chains containing sulfo binding groups onto these matrix beads, the cation-exchange cryogel beads for protein separation were produced. The results showed that at the aqueous phase velocities from 0.5 to 2.0 cm/s and the total velocities of the water-immiscible phase from 2.0 to 6.0 cm/s, the obtained cryogel beads by the present method have narrow size distributions with most of the bead diameters in the range from 800 to 1500 ?m with supermacropores in sizes of about 3-50 ?m. These beads also have high porosities with the averaged maximum porosity of 96.9% and the mean effective porosity of 86.2%, which are close to those of the polyacrylamide-based cryogel monoliths. The packed bed using the cryogel beads with mean diameter of 1248 ?m, as an example, has reasonable and acceptable liquid dispersion, but high water permeability (4.29 × 10?¹? m²) and high bed voidage (90.2%) owing to the supermacropores within the beads, enhanced the rapid binding and separation of protein from the feedstock even at high flow velocities. The purity of the obtained lysozyme from chicken egg white by one-step chromatography using the packed bed was in the range of about 78-92% at the flow velocities of 0.5-15 cm/min, indicating that the present cryogel beads could be an effective chromatographic adsorbent for primary bioseparation. PMID:22695698

Yun, Junxian; Tu, Changming; Lin, Dong-Qiang; Xu, Linhong; Guo, Yantao; Shen, Shaochuan; Zhang, Songhong; Yao, Kejian; Guan, Yi-Xin; Yao, Shan-Jing

2012-07-20

360

Magnetic state of the structural separated anion-deficient La0.70Sr0.30MnO2.85 manganite  

NASA Astrophysics Data System (ADS)

The results of neutron diffraction studies of the La0.70Sr0.30MnO2.85 compound and its behavior in an external magnetic field are stated. It is established that in the 4-300 K temperature range, two structural perovskite phases coexist in the sample, which differ in symmetry (groups Rbar 3c and I4/ mcm). The reason for the phase separation is the clustering of oxygen vacancies. The temperature (4-300 K) and field (0-140 kOe) dependences of the specific magnetic moment are measured. It is found that in zero external field, the magnetic state of La0.70Sr0.30MnO2.85 is a cluster spin glass, which is the result of frustration of Mn3+-O-Mn3+ exchange interactions. An increase in external magnetic field up to 10 kOe leads to fragmentation of ferromagnetic clusters and then to an increase in the degree of polarization of local spins of manganese and the emergence of long-range ferromagnetic order. With increasing magnetic field up to 140 kOe, the magnetic ordering temperature reaches 160 K. The causes of the structural and magnetic phase separation of this composition and formation mechanism of its spin-glass magnetic state are analyzed.

Trukhanov, S. V.; Trukhanov, A. V.; Vasiliev, A. N.; Balagurov, A. M.; Szymczak, H.

2011-11-01

361

Thermal-Structural Coupled Analysis of ITER Torus Cryo-Pump Housing  

NASA Astrophysics Data System (ADS)

An ITER torus cryo-pump housing (TCPH), which encloses a torus cryo-pump, is connected to a vacuum vessel (VV) by a set of associated double bellows. There are complicated loads due to two different operating states (pumping and regeneration) and foreseeable accidents with the cryo-pump. This paper describes a thermal-structural coupled analysis of the present TCPH according to the allowable stress criteria of RCC-MR, in which the worst cases and outcomes of various load combinations are obtained. Meanwhile, optimization of the structure has been carried out to obtain positive analysis results and an adequate safety margin.

Wang, Songke; Song, Yuntao; Xie, Han; Lei, Mingzhun

2012-11-01

362

A Unique BSL-3 Cryo-Electron Microscopy Laboratory at UTMB  

PubMed Central

This article describes a unique cryo-electron microscopy (CryoEM) facility to study the three-dimensional organization of viruses at biological safety level 3 (BSL-3). This facility, the W. M. Keck Center for Virus Imaging, has successfully operated for more than a year without incident and was cleared for select agent studies by the Centers for Disease Control and Prevention (CDC). Standard operating procedures for the laboratory were developed and implemented to ensure its safe and efficient operation. This facility at the University of Texas Medical Branch (Galveston, TX) is the only such BSL-3 CryoEM facility approved for select agent research.

Sherman, Michael B.; Freiberg, Alexander N.; Razmus, Dennis; Yazuka, Shintaro; Koht, Craig; Hilser, Vincent J.; Lemon, Stanley M.; Brocard, Anne-Sophie; Zimmerman, Dee; Chiu, Wah; Watowich, Stanley J.; Weaver, Scott C.

2010-01-01

363

Miniature Joule Thomson (JT) CryoCoolers for Propellant Management  

NASA Technical Reports Server (NTRS)

A proof-of-concept project is proposed here that would attempt to demonstrate how miniature cryocoolers can be used to chill the vacuum jacket line of a propellant transfer line and thus to achieve transfer line pre-chill, zero boil off and possible propellant densification. The project would be performed both at UCF and KSC, with all of the cryogenic testing taking place in the KSC cryogenic test bed. A LN2 line available in that KSC test facility would serve to simulate a LOX transfer line. Under this project, miniature and highly efficient cold heads would be designed. Two identical cold heads will be fabricated and then integrated with a JT-type cryogenic system (consisting of a common compressor and a common external heat exchanger). The two cold heads will be integrated into the vacuum jacket of a LN2 line in the KSC cryo lab, where the testing will take place.

Kapat, Jay; Chow, Louis

2002-01-01

364

Model-based particle picking for cryo-electron microscopy.  

PubMed

We describe an algorithm for finding particle images in cryo-EM micrographs. The algorithm starts from a crude 3D map of the target particle, computed from a relatively small number of manually picked images, and then projects the map in many different directions to give synthetic 2D templates. The templates are clustered and averaged and then cross-correlated with the micrographs. A probabilistic model of the imaging process then scores cross-correlation peaks to produce the final picks. We give quantitative results on two quite different target particles: keyhole limpet hemocyanin and p97 AAA ATPase. On these particles our automatic particle picker shows human performance level, as measured by the Fourier shell correlations of 3D reconstructions. PMID:15065683

Wong, H Chi; Chen, Jindong; Mouche, Fabrice; Rouiller, Isabelle; Bern, Marshall

2004-01-01

365

Electron microscopy of flatworms standard and cryo-preparation methods.  

PubMed

Electron microscopy (EM) has long been indispensable for flatworm research, as most of these worms are microscopic in dimension and provide only a handful of characters recognizable by eye or light microscopy. Therefore, major progress in understanding the histology, systematics, and evolution of this animal group relied on methods capable of visualizing ultrastructure. The rise of molecular and cellular biology renewed interest in such ultrastructural research. In the light of recent developments, we offer a best-practice guide for users of transmission EM and provide a comparison of well-established chemical fixation protocols with cryo-processing methods (high-pressure freezing/freeze-substitution, HPF/FS). The organisms used in this study include the rhabditophorans Macrostomum lignano, Polycelis nigra and Dugesia gonocephala, as well as the acoel species Isodiametra pulchra. PMID:20869529

Salvenmoser, Willi; Egger, Bernhard; Achatz, Johannes G; Ladurner, Peter; Hess, Michael W

2010-01-01

366

Isolation of prostate cancer cell subpopulations of functional interest by use of an on-chip magnetic bead-based cell separator  

Microsoft Academic Search

This work presents the design, fabrication and characterization of a modular magnetic bead-based cell separation device developed for the sequential sorting of a heterogeneous prostate cancer (CaP) cell population. The chief aim is cell sorting carried out on the basis of surface marker expression, serially selecting cellular subpopulations for capture by the use of antibody-coated magnetic beads. The markers of

Matthew D Estes; Bin Ouyang; Shuk-mei Ho; Chong H Ahn

2009-01-01

367

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

368

Synthesis and characterization of magnetic hexacyanoferrate (II) polymeric nanocomposite for separation of cesium from radioactive waste solutions.  

PubMed

Nanocrystalline potassium zinc hexacyanoferrate loaded on nanoscale magnetite substrate was successfully synthesized for significantly enhanced removal of cesium from low-level radioactive wastes. A description was given for preparation and properties of these precursors. The physicochemical properties of these nanocomposites were determined using different techniques including Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), and energy dispersive spectroscopy (EDS). Data clarified that supporting potassium zinc hexacyanoferrates on iron ferrite nanoparticles increased their thermal stability. Further, Fourier transform infrared spectra confirmed that the nanocomposites were well coordinated and incorporated in the polymer matrix. The average particle sizes, of these nanoparticles, determined by SEM had a good agreement with XRD results. Based on characterization data, the prepared zinc hexacyanoferrates were proposed to have a zeolitic rhombohedral structure with cavities can host alkali metal ions and water molecules. The magnetic analysis showed a super-paramagnetic behavior. Batch technique was applied to evaluate the influences of initial pH value, contact time, and competing cations on the efficiency of cesium removal. The sorption process was fast initially, and maximum separation was attained within 2h of contact. Cesium exchange was independent from pH value and deviate from ideal exchange phenomena. In neutral solutions, Cs(+) was retained through exchange with K(+); however, in acidic solution, phase transformation was proposed. Sorption capacity of these materials attained values amounted 1965 mg g(-1). The synthesized nanocomposites exhibited different affinities toward Cs(I), Co(II), and Eu(III) elements and showed a good ability to separate them from each other. PMID:23000210

Sheha, Reda R

2012-12-15

369

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

370

Cryo-Ablation for Septal Tachycardia Substrates in Pediatric Patients MidTerm Results  

Microsoft Academic Search

OBJECTIVES The aim of this study was to evaluate the efficacy and safety of catheter-based cryo-therapy for septal tachycardia substrates in pediatric patients. BACKGROUND Cryo-therapy may be particularly useful for ablation of septal tachycardias, including atrioventricular nodal re-entry tachycardia (AVNRT), atrioventricular reciprocating tachy- cardia (AVRT), and ventricular tachycardia (VT) originating high in the conduction system. METHODS Thirty-one pediatric patients (median

Aya Miyazaki; Andrew D. Blaufox; David L. Fairbrother; J. Philip Saul

371

Retrovirus envelope protein complex structure in situ studied by cryo-electron tomography  

Microsoft Academic Search

We used cryo-electron tomography in conjunction with single-particle averaging techniques to study the structures of frozen-hydrated envelope glycoprotein (Env) complexes on intact Moloney murine leukemia retrovirus particles. Cryo-electron tomography allows 3D imaging of viruses in toto at a resolution sufficient to locate individual macromolecules, and local averaging of abundant complexes substantially improves the resolution. The averaging of repetitive features in

Friedrich Förster; Ohad Medalia; Nathan Zauberman; Wolfgang Baumeister; Deborah Fass

2005-01-01

372

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

373

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 10.2 ng/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

2013-11-15

374

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

2013-01-01

375

Transcranial magnetic stimulation in a finger-tapping task separates motor from timing mechanisms and induces frequency doubling.  

PubMed

We study the interplay between motor programs and their timing in the brain by using precise pulses of transcranial magnetic stimulation (TMS) applied to the primary motor cortex. The movement of the finger performing a tapping task is periodically perturbed in synchronization with a metronome. TMS perturbation can profoundly affect both the finger trajectory and its kinematics, but the tapping accuracy itself is surprisingly not affected. The motion of the finger during the TMS perturbation can be categorized into two abnormal behaviors that subjects were unaware of: a doubling of the frequency of the tap and a stalling of the finger for half the period. More stalls occurred as the tapping frequency increased. In addition, an enhancement of the velocity of the finger on its way up was observed. We conclude that the timing process involved in controlling the tapping movement is separate from the motor processes in charge of execution of the motor commands. We speculate that the TMS is causing a release of the motor plan ahead of time into activation mode. The observed doubles and stalls are then the result of an indirect interaction in the brain, making use of an existing motor plan to correct the preactivation and obtain the temporal goal of keeping the beat. PMID:17488200

Levit-Binnun, Nava; Handzy, Nestor Z; Peled, Avi; Modai, Ilan; Moses, Elisha

2007-05-01

376

Quantum dynamics of charged and neutral magnetic solitons: Spin-charge separation in the one-dimensional Hubbard model  

NASA Astrophysics Data System (ADS)

We demonstrate that the configuration interaction (CI) approximation recaptures essential features of the exact (Bethe-ansatz) solution to the one-dimensional (1D) Hubbard model. As such, it provides a valuable route for describing effects that go beyond mean-field theory for strongly correlated electron systems in higher dimensions. The CI method systematically describes fluctuation and quantum tunneling corrections to the Hartree-Fock approximation (HFA). HFA predicts that doping a half-filled Hubbard chain leads to the appearance of charged spin polarons or charged domain-wall solitons in the antiferromagnetic background. The CI method, on the other hand, describes the quantum dynamics of these charged magnetic solitons and quantum tunneling effects between various mean-field configurations. In this paper, we test the accuracy of the CI method against the exact solution of the one-dimensional Hubbard model. We find remarkable agreement between the energy of the mobile charged bosonic domain wall (as given by the CI method) and the exact energy of the doping hole (as given by the Bethe ansatz) for the entire U/t range. The CI method also leads to a clear demonstration of the spin-charge separation in one dimension. Addition of one doping hole to the half-filled antiferromagnetic chain results in the appearance of two different carriers: a charged bosonic domain wall (which carries the charge but no spin) and a neutral spin-1/2 domain wall (which carries the spin but no charge).

Berciu, Mona; John, Sajeev

2000-04-01

377

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

2013-03-01

378

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

2011-03-15

379

Single-step antibody-based affinity cryo-electron microscopy for imaging and structural analysis of macromolecular assemblies.  

PubMed

Single particle cryo-electron microscopy (cryo-EM) is an emerging powerful tool for structural studies of macromolecular assemblies (i.e., protein complexes and viruses). Although single particle cryo-EM requires less concentrated and smaller amounts of samples than X-ray crystallography, it remains challenging to study specimens that are low-abundance, low-yield, or short-lived. The recent development of affinity grid techniques can potentially further extend single particle cryo-EM to these challenging samples by combining sample purification and cryo-EM grid preparation into a single step. Here we report a new design of affinity cryo-EM approach, cryo-SPIEM, that applies a traditional pathogen diagnosis tool Solid Phase Immune Electron Microscopy (SPIEM) to the single particle cryo-EM method. This approach provides an alternative, largely simplified and easier to use affinity grid that directly works with most native macromolecular complexes with established antibodies, and enables cryo-EM studies of native samples directly from cell cultures. In the present work, we extensively tested the feasibility of cryo-SPIEM with multiple samples including those of high or low molecular weight, macromolecules with low or high symmetry, His-tagged or native particles, and high- or low-yield macromolecules. Results for all these samples (non-purified His-tagged bacteriophage T7, His-tagged Escherichiacoli ribosomes, native Sindbis virus, and purified but low-concentration native Tulane virus) demonstrated the capability of cryo-SPIEM approach in specifically trapping and concentrating target particles on TEM grids with minimal view constraints for cryo-EM imaging and determination of 3D structures. PMID:24780590

Yu, Guimei; Vago, Frank; Zhang, Dongsheng; Snyder, Jonathan E; Yan, Rui; Zhang, Ci; Benjamin, Christopher; Jiang, Xi; Kuhn, Richard J; Serwer, Philip; Thompson, David H; Jiang, Wen

2014-07-01

380

Performance of the LHC final prototype and first pre-series superconducting dipole magnets  

Microsoft Academic Search

Within the LHC cryo-dipole program, six full-scale superconducting prototypes of final design were built in collaboration between Industry and CERN, followed by launching the manufacture of pre-series magnets. Five prototypes and the first of the pre-series magnets were tested at CERN. This paper reviews the main features and the performance of the cryo-dipoles tested at 4.2 K and 1.8 K.

L. Bottura; G. D'Angelo; M. Gateau; P. Legrand; M. Modena; K. Naoui; D. Perini; P. Pugnat; S. Sanfilippo; F. Savary; Walter Scandale; A. Siemko; P. Sievers; G. Spigo; J. Vlogaert; C. Wyss

2002-01-01

381

Cryo-TEM analysis of collagen fibrillar structure.  

PubMed

Fibrillar collagens are important structural proteins and are known to be closely associated with mineral in the case of mineralized tissues. However, the precise role of collagen in the mineralization process remains unclear, and the evaluation of structural differences in collagen from mineralized and nonmineralized tissues may be instructive in this regard. Here, we review the use of cryo-transmission electron microscopy to investigate the axial structure of collagen fibrils in tissue sections from both mineralizing and nonmineralizing tissues. By examining collagen fibrillar structure in an unstained frozen-hydrated state, it is possible to avoid artifacts normally associated with staining and dehydration that are required for conventional TEM. We describe both sample preparation and image analysis with emphasis on the particular challenges of using image averaging techniques, which can be used to overcome the low signal-to-noise ratio that is inherent in this technique. Detailed banding patterns can be obtained from averaged images, and these can be analyzed to obtain quantitative information on fibril periodicity and structure. PMID:24188768

Quan, Bryan D; Sone, Eli D

2013-01-01

382

A cylindrical specimen holder for electron cryo-tomography  

PubMed Central

The use of slab-like flat specimens for electron cryo-tomography restricts the range of viewing angles that can be used. This leads to the “missing wedge” problem, which causes artefacts and anisotropic resolution in reconstructed tomograms. Cylindrical specimens provide a way to eliminate the problem, since they allow imaging from a full range of viewing angles around the tilt axis. Such specimens have been used before for tomography of radiation-insensitive samples at room temperature, but never for frozen-hydrated specimens. Here, we demonstrate the use of thin-walled carbon tubes as specimen holders, allowing the preparation of cylindrical frozen-hydrated samples of ribosomes, liposomes and whole bacterial cells. Images acquired from these cylinders have equal quality at all viewing angles, and the accessible tilt range is restricted only by the physical limits of the microscope. Tomographic reconstructions of these specimens demonstrate that the effects of the missing wedge are substantially reduced, and could be completely eliminated if a full tilt range was used. The overall quality of these tomograms is still lower than that obtained by existing methods, but improvements are likely in future.

Palmer, Colin M.; Lowe, Jan

2014-01-01

383

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

384

Phase Separation in Submicron Organic Aerosol  

NASA Astrophysics Data System (ADS)

Aerosol particles affect climate through heterogeneous chemistry, the scattering and absorption of radiation, and through their role as seeds for cloud condensation and ice nuclei. These interactions depend in part on the internal structure of the particles. To investigate the chemical and physical principles that determine the internal structure of organic aerosol, we have characterized the morphology of laboratory-generated, dry, internally mixed particles in the submicron size regime using cryo-transmission electron microscopy (cryo-TEM). We have focused on the well-studied system of dicarboxylic acids mixed with ammonium sulfate. The morphology of dry, organic aerosol particles depends upon the organic solubility, rather than the organic O:C ratio. We observe homogeneous structures for soluble organic compounds and phase separated structures for insoluble organic compounds. The phase-separated structures are partially engulfed rather than core-shell. For organic compounds of intermediate solubility, the aerosol morphology is dependent on the particle size, where the large particles are partially engulfed and the small particles are homogeneous. In addition to our single particle technique, we use cavity ring-down spectroscopy and computation to understand the average particle structure. Our results demonstrate the use of cryo-TEM and cavity ring-down spectroscopy to investigate aerosol structure in the submicron size regime.

Freedman, M. A.; Veghte, D. P.; Altaf, M. B.

2013-12-01

385

Human functional magnetic resonance imaging reveals separation and integration of shape and motion cues in biological motion processing.  

PubMed

In a series of human functional magnetic resonance imaging experiments, we systematically manipulated point-light stimuli to identify the contributions of the various areas implicated in biological motion processing (for review, see Giese and Poggio, 2003). The first experiment consisted of a 2 x 2 factorial design with global shape and kinematics as factors. In two additional experiments, we investigated the contributions of local opponent motion, the complexity of the portrayed movement and a one-back task to the activation pattern. Experiment 1 revealed a clear separation between shape and motion processing, resulting in two branches of activation. A ventral region, extending from the lateral occipital sulcus to the posterior inferior temporal gyrus, showed a main effect of shape and its extension into the fusiform gyrus also an interaction. The dorsal region, including the posterior inferior temporal sulcus and the posterior superior temporal sulcus (pSTS), showed a main effect of kinematics together with an interaction. Region of interest analysis identified these interaction sites as the extrastriate and fusiform body areas (EBA and FBA). The local opponent motion cue yielded only little activation, limited to the ventral region (experiment 3). Our results suggest that the EBA and the FBA correspond to the initial stages in visual action analysis, in which the performed action is linked to the body of the actor. Moreover, experiment 2 indicates that the body areas are activated automatically even in the absence of a task, whereas other cortical areas like pSTS or frontal regions depend on the complexity of movements or task instructions for their activation. PMID:19494153

Jastorff, Jan; Orban, Guy A

2009-06-01

386

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

387

Magnetic, thermal and transport properties of phase-separated La0.27Nd0.4Ca0.33MnO3  

NASA Astrophysics Data System (ADS)

The magnetic, resistive and thermal properties of the phase-separated compound La0.27Nd0.4Ca0.33MnO3 have been experimentally studied. The sample is found to experience a charge/orbital ordering transition at ~175 K and an antiferromagnetic (AFM) transition at ~156 K without a magnetic field. A magnetic field stabilizes the ferromagnetic (FM) order and the field-induced FM phase coexists with the AFM phase under a field below 2 T in the temperature range below TC?110 K. However, the magnetic entropy change accompanying the AFM-FM transition is negligibly small when TCTN. A general relation between resistivity and magnetization, ? = A0Texp[(?-800m2)/T] (m = normalized magnetization), is established for the paramagnetic phase, which is also applicable to other compounds with different characters, such as the La0.67Ca0.33MnO3 film and the La0.474Bi0.193Ca0.33Mn0.994Cr0.006O3 and Eu0.55Sr0.45MnO3 ceramics. In the FM state, the resistivity is quite sensitive to the change of spin alignment and exhibits an exponential decrease with magnetization ? = ?0exp(-22.7m). Field-induced phase separation is believed to be responsible for the distinct properties of La0.27Nd0.4Ca0.33MnO3.

Wang, J. Z.; Sun, J. R.; Liu, G. J.; Hu, F. X.; Chen, R. J.; Zhao, T. Y.; Shen, B. G.

2008-08-01

388

Mechanical behavior and magnetic separation of quasi-one-dimensional SnO2 nanostructures: A technique for achieving monosize nanobelts/nanowires  

NASA Astrophysics Data System (ADS)

The as-synthesized nanowires and nanobelts usually have a large size distribution. We demonstrate here a ball milling technique for narrowing the size distribution of oxide nanobelts and nanowires. High-resolution scanning and transmission electron microscopy reveals that the one-dimensional SnO2 nanostructures with size >150 nm are sensitive to the milling effect and most of them were fractured into nanoparticles even after a short-time milling. These nanoparticles contain magnetic Fe components, which could be effectively separated from those nanobelts by employing a magnetic field. This feature promises a potentials application in the nanostructured materials separation. It was also found that the dominant size of the survived nanostructures is <100 nm. The good mechanical behavior of the nanostructures are not only related to the superior mechanical toughness due to small size, but also related to the low defect density.

Jin, Z. Q.; Ding, Y.; Wang, Z. L.

2005-04-01

389

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

2011-10-21

390

Improved accuracy of U-Pb zircon dating by selection of more concordant fractions using a high gradient magnetic separation technique  

NASA Astrophysics Data System (ADS)

A loop of soft iron wire or a paper clip or a ferromagnetic grid mounted between the poles of an electromagnet picks up and allows further magnetic separation of zircons previously found to be non-magnetic on a Frantz Isodynamic Separator. Tests on previously analysed samples indicate that most such zircons that are fairly discordant (say ~10%) can be picked up and isolated from associated grains that are more concordant. Tests on new samples indicate that even when most grains can be picked up the last few percent of the sample contain less uranium, and are more concordant than the bulk sample. The degree of discordance is the dominant factor affecting the uncertainty of U-Pb zircon ages both because of the error amplification in projections, and because the assumption of a simple two-stage system may not be valid. Only by eliminating or reducing discordance can errors approaching the uncertainty in a single analysis, say ±2 m.y. for 2700 m.y. rocks, be achieved. Rutile normally concentrated with zircon as non-magnetic has been successfully removed from a small amount of low uranium zircon, using the high intensity separation technique.

Krogh, T. E.

1982-04-01

391

Influence of the static high magnetic field on the liquid-liquid phase separation during solidifying the hyper-monotectic alloys  

NASA Astrophysics Data System (ADS)

Magnetic in-situ quenching refers to fixing and quenching the sample at a static high magnetic field (SHMF) up to 18 T; it has been achieved by a specially designed facility. Zn-7wt%Bi and Zn-10wt%Bi hyper-monotectic melts were quenched under different magnetic flux densities to investigate the influence of SHMF on the liquid-liquid phase separation process in solidifying hyper-monotectic alloys. Because this separation is mainly caused by the growth of minority phase droplets (Bi droplets in the present study), and such growth is attributed to the diffusion of Bi element and the coalescence between the droplets, the influence of SHMF on the growth of Bi droplets was analyzed. Results show that the imposed SHMF prevented the formation of layered structure in the Zn-10wt%Bi alloy and refined the Bi particles in the Zn-7wt%Bi alloy, which indicates that the SHMF retarded the liquid-liquid phase separation during solidifying the hyper-monotectic alloys. Indeed, the two motions of droplets in determining the coalescence, Marangoni migration and Stocks sedimentation, were slowed down by the applied SHMF. Analytical estimations of the magnitude of such damping effect have been made and show that the 18 T SHMF could reduce the speed of Stokes sedimentation and Marangoni migration of the minority phase droplets by about 95.5 % and 62.4 %, respectively.

Wang, J.; Zhong, Y. B.; Fautrelle, Y.; Zheng, T. X.; Li, F.; Ren, Z. M.; Debray, F.

2013-09-01

392

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

393

Synthesis of a Thin-Layer MnO2 Nanosheet-Coated Fe3O4 Nanocomposite as a Magnetically Separable Photocatalyst.  

PubMed

A facile hydrothermal method combined with a mild ultrasonic means has been developed for the fabrication of a magnetically recyclable thin-layer MnO2 nanosheet-coated Fe3O4 nanocomposite. The photocatalytic studies suggest that the MnO2/Fe3O4 nanocomposite shows excellent photocatalytic efficiency and stability simultaneously for the degradation of methylene blue under UV-vis light irradiation. Moreover, its good acid resistance and stable recyclability are very important for its future practical application as a photocatalyst. Magnetic measurements verify that the MnO2/Fe3O4 nanocomposite possesses a ferromagnetic nature, which can be effectively separated for reuse by simply applying an external magnetic field after the photocatalytic reaction. This novel composite material may have potential applications in water treatment, degradation of dye pollutants, and environmental cleaning. PMID:24856355

Zhang, Lishu; Lian, Jianshe; Wu, Longyun; Duan, Zhenrong; Jiang, Jun; Zhao, Lijun

2014-06-17

394

Novel Phase Separation and Magnetic Volume Tuning in Underdoped NaFe1-xCoxAs (x ˜0.01)  

NASA Astrophysics Data System (ADS)

NaFeAs is a quasi-2D pnictide parent compound with a weak magnetic moment and separate structural and antiferromagnetic transitions. Because Co doping leads to a superconductor with Tc˜20 K at a very low optimal doping of x = 0.02, NaFe1-xCoxAs is uniquely suited to sensitive studies of the cohabitation and competition between magnetism and superconductivity. Using NMR as a local probe of both antiferromagnetic order and superconductivity, we have compared Knight shifts and relaxation rates on the Na, As, and Co nuclei. Above Tc, we find weak doping inhomogeneity, in the form of residual paramagnetic regions with differing TN values, and a strongly field-controlled magnetic volume. Below Tc, we observe a strong competition between antiferromagnetism and superconductivity, in which the temperature is the dominant control parameter, suppressing the magnetic volume fraction very significantly in favor of the superconducting one, while the external field suppresses Tc. Our results suggest both a microscale phase separation in real space and in reciprocal space a competition between two order parameters requiring the same electrons on the quasi-2D Fermi surface.

Ma, Long; Dai, J.; Lu, X. R.; Tan, Guotai; Song, Yu; Dai, Pengcheng; Zhang, C. L.; Normand, B.; Yu, Weiqiang

2013-03-01

395

Study on the Effect of Melt Convection on Phase Separation Structures in Undercooled CuCo Alloys Using an Electromagnetic Levitator Superimposed with a Static Magnetic Field  

NASA Astrophysics Data System (ADS)

We studied the effect of melt convection on phase separation structures in undercooled Cu80Co20 alloys by using an electromagnetic levitator, where a static magnetic field was applied to control convection in the molten alloys. It was found that, when the static magnetic field was relatively small, dispersed structures with relatively fine Co-rich spheres distributed in the matrix of the Cu-rich phase were observed. However, a few large, coalesced Co-rich phases appeared in the Cu-rich matrix when the magnetic field exceeded a certain value, i.e., approximately 1.5 T in this study. The mean diameter of the droplet-shaped Co-rich phases distributed in the matrix of the Cu-rich phase increased gradually with the magnetic field and increased rapidly at approximately 1.5 T. Moreover, it was speculated from the result of periodic laser heating that the marked change in the phase separation structures at approximately 1.5 T might be due to a convective transition from turbulent flow to laminar flow in the molten sample, where the time variation of temperature in the lower part of the electromagnetically levitated molten sample was measured when the upper part of the sample was periodically heated.

Sugioka, Ken-ichi; Inoue, Takamitsu; Kitahara, Tsubasa; Kurosawa, Ryo; Kubo, Masaki; Tsukada, Takao; Uchikoshi, Masahito; Fukuyama, Hiroyuki

2014-03-01

396

Structure, assembly and dynamics of macromolecular complexes by single particle cryo-electron microscopy  

PubMed Central

Background Proteins in their majority act rarely as single entities. Multisubunit macromolecular complexes are the actors in most of the cellular processes. These nanomachines are hold together by weak protein-protein interactions and undergo functionally important conformational changes. TFIID is such a multiprotein complex acting in eukaryotic transcription initiation. This complex is first to be recruited to the promoter of the genes and triggers the formation of the transcription preinitiation complex involving RNA polymerase II which leads to gene transcription. The exact role of TFIID in this process is not yet understood. Methods Last generation electron microscopes, improved data collection and new image analysis tools made it possible to obtain structural information of biological molecules at atomic resolution. Cryo-electron microscopy of vitrified samples visualizes proteins in a fully hydrated, close to native state. Molecular images are recorded at liquid nitrogen temperature in low electron dose conditions to reduce radiation damage. Digital image analysis of these noisy images aims at improving the signal-to-noise ratio, at separating distinct molecular views and at reconstructing a three-dimensional model of the biological particle. Results Using these methods we showed the early events of an activated transcription initiation process. We explored the interaction of the TFIID coactivator with the yeast Rap1 activator, the transcription factor TFIIA and the promoter DNA. We demonstrated that TFIID serves as an assembly platform for transient protein-protein interactions, which are essential for transcription initiation. Conclusions Recent developments in electron microscopy have provided new insights into the structural organization and the dynamic reorganization of large macromolecular complexes. Examples of near-atomic resolutions exist but the molecular flexibility of macromolecular complexes remains the limiting factor in most case. Electron microscopy has the potential to provide both structural and dynamic information of biological assemblies in order to understand the molecular mechanisms of their functions.

2013-01-01

397

Analysis of the Intact Surface Layer of Caulobacter crescentus by Cryo-Electron Tomography ? †  

PubMed Central

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.

Amat, Fernando; Comolli, Luis R.; Nomellini, John F.; Moussavi, Farshid; Downing, Kenneth H.; Smit, John; Horowitz, Mark

2010-01-01

398

Magnetic phase separation-induced coercivity enhancement in epitaxial Nd0.5Sr0.5CoO3 films  

NASA Astrophysics Data System (ADS)

Interfacial magneto-electronic phase separation has recently been observed in epitaxial thin films of the doped perovskite cobaltite La1-xSrxCoO3 at doping values where no such phase separation exists in bulk. Such systems also display anomalously large coercivity, which is not understood. To achieve a better understanding of this phenomenon we have extended this study to Nd1-xSrxCoO3 (x = 0.5), the perovskite cobaltite with the largest coercivity in bulk. Thin films of Nd0.5Sr0.5CoO3 are grown via high pressure reactive sputtering on SrTiO3 (001) substrates. We have observed a rapid deterioration in magnetization and onset of large intercluster-type magnetoresistance below a critical thickness of 80 å, signatures of interfacial magneto-electronic phase separation also seen in our earlier work on La1-xSrxCoO3. The temperature, angular, and thickness dependence of the coercivity (Hc) was studied using magnetoresistance. Low temperature HC values become very large (up to 3.6 Tesla) at low thickness, and a strong, superlinear T dependence emerges. We propose that the coercivity enhancement arises due to efficient domain wall pinning by the inhomogeneous magnetically phase separated region near the SrTiO3 substrate.

Sharma, M.; Gazquez, J.; Varela, M.; Leighton, C.

2009-03-01

399

Separate structure of two branches of sheared slab etai mode and effects of plasma rotation shear in weak magnetic shear region  

NASA Astrophysics Data System (ADS)

The separate structure of two branches of the sheared slab etai mode near the minimum-q magnetic surface is analysed and the effects of plasma rotation shears are considered in the weak magnetic shear region. Results show that the separation condition depends on the non-monotonous q profile and the deviation of rational surface from the minimum-q surface. Furthermore, it is found that the diamagnetic rotation shear may suppress the perturbation of the sheared slab etai mode at one side of the minimum-q surface, the poloidal rotation shear from the sheared E × B flow has a similar role to the slab mode structure when it possesses a direction same as the diamagnetic shear. A plausible interrelation between the separate structures of the two branches of the sheared slab mode and the discontinuity or gap of the radially global structure of the drift wave near the minimum-q surface observed in the toroidal particle simulation (Kishimoto Y et al 1998 Plasma Phys. Control. Fusion 40 A663) is discussed. It seems to support such a viewpoint: the double or/and global branches of the sheared slab etai mode near the minimum-q surface may become a bridge to connect the radially global structures of the drift wave at two sides of the minimum-q surface and the discontinuity may originate from the separate structures of these slab modes for a flatter q profile.

Li, Jiquan; Kishimoto, Y.; Tuda, T.

2000-04-01

400

Isotope Separation System.  

National Technical Information Service (NTIS)

This invention relates to the separation of isotopes and in particular to a magnetic separation system for ions selectively ionized by laser radiation. In this invention for the enrichment of exp 235 U isotopes the magnetic field is applied with a force w...

H. K. Forsen

1976-01-01

401

Super-Resolution Microscopy Using Standard Fluorescent Proteins in Intact Cells under Cryo-Conditions.  

PubMed

We introduce a super-resolution technique for fluorescence cryo-microscopy based on photoswitching of standard genetically encoded fluorescent marker proteins in intact mammalian cells at low temperature (81 K). Given the limit imposed by the lack of cryo-immersion objectives, current applications of fluorescence cryo-microscopy to biological specimens achieve resolutions between 400-500 nm only. We demonstrate that the single molecule characteristics of reversible photobleaching of mEGFP and mVenus at liquid nitrogen temperature are suitable for the basic concept of single molecule localization microscopy. This enabled us to perform super-resolution imaging of vitrified biological samples and to visualize structures in unperturbed fast frozen cells for the first time with a structural resolution of ?125 nm (average single molecule localization accuracy ?40 nm), corresponding to a 3-5 fold resolution improvement. PMID:24884378

Kaufmann, Rainer; Schellenberger, Pascale; Seiradake, Elena; Dobbie, Ian M; Jones, E Yvonne; Davis, Ilan; Hagen, Christoph; Grünewald, Kay

2014-07-01

402

Super-Resolution Microscopy Using Standard Fluorescent Proteins in Intact Cells under Cryo-Conditions  

PubMed Central

We introduce a super-resolution technique for fluorescence cryo-microscopy based on photoswitching of standard genetically encoded fluorescent marker proteins in intact mammalian cells at low temperature (81 K). Given the limit imposed by the lack of cryo-immersion objectives, current applications of fluorescence cryo-microscopy to biological specimens achieve resolutions between 400–500 nm only. We demonstrate that the single molecule characteristics of reversible photobleaching of mEGFP and mVenus at liquid nitrogen temperature are suitable for the basic concept of single molecule localization microscopy. This enabled us to perform super-resolution imaging of vitrified biological samples and to visualize structures in unperturbed fast frozen cells for the first time with a structural resolution of ?125 nm (average single molecule localization accuracy ?40 nm), corresponding to a 3–5 fold resolution improvement.

2014-01-01

403

Coordinate transformation based cryo-correlative methods for electron tomography and focused ion beam milling.  

PubMed

Correlative microscopy allows imaging of the same feature over multiple length scales, combining light microscopy with high resolution information provided by electron microscopy. We demonstrate two procedures for coordinate transformation based correlative microscopy of vitrified biological samples applicable to different imaging modes. The first procedure aims at navigating cryo-electron tomography to cellular regions identified by fluorescent labels. The second procedure, allowing navigation of focused ion beam milling to fluorescently labeled molecules, is based on the introduction of an intermediate scanning electron microscopy imaging step to overcome the large difference between cryo-light microscopy and focused ion beam imaging modes. These methods make it possible to image fluorescently labeled macromolecular complexes in their natural environments by cryo-electron tomography, while minimizing exposure to the electron beam during the search for features of interest. PMID:24332462

Fukuda, Yoshiyuki; Schrod, Nikolas; Schaffer, Miroslava; Feng, Li Rebekah; Baumeister, Wolfgang; Lucic, Vladan

2014-08-01

404

Phasing of the Triatoma virus diffraction data using a cryo-electron microscopy reconstruction.  

PubMed

The blood-sucking reduviid bug Triatoma infestans, one of the most important vector of American human trypanosomiasis (Chagas disease) is infected by the Triatoma virus (TrV). TrV has been classified as a member of the Cripavirus genus (type cricket paralysis virus) in the Dicistroviridae family. This work presents the three-dimensional cryo-electron microscopy (cryo-EM) reconstruction of the TrV capsid at about 25 A resolution and its use as a template for phasing the available crystallographic data by the molecular replacement method. The main structural differences between the cryo-EM reconstruction of TrV and other two viruses, one from the same family, the cricket paralysis virus (CrPV) and the human rhinovirus 16 from the Picornaviridae family are presented and discussed. PMID:18308357

Estrozi, L F; Neumann, E; Squires, G; Rozas-Dennis, G; Costabel, M; Rey, F A; Guérin, D M A; Navaza, J

2008-05-25

405

Three-dimensional structures of pathogenic and saprophytic Leptospira species revealed by cryo-electron tomography.  

PubMed

Leptospira interrogans is the primary causative agent of the most widespread zoonotic disease, leptospirosis. An in-depth structural characterization of L. interrogans is needed to understand its biology and pathogenesis. In this study, cryo-electron tomography (cryo-ET) was used to compare pathogenic and saprophytic species and examine the unique morphological features of this group of bacteria. Specifically, our study revealed a structural difference between the cell envelopes of L. interrogans and Leptospira biflexa involving variations in the lipopolysaccharide (LPS) layer. Through cryo-ET and subvolume averaging, we determined the first three-dimensional (3-D) structure of the flagellar motor of leptospira, with novel features in the flagellar C ring, export apparatus, and stator. Together with direct visualization of chemoreceptor arrays, DNA packing, periplasmic filaments, spherical cytoplasmic bodies, and a unique "cap" at the cell end, this report provides structural insights into these fascinating Leptospira species. PMID:22228733

Raddi, Gianmarco; Morado, Dustin R; Yan, Jie; Haake, David A; Yang, X Frank; Liu, Jun

2012-03-01

406

Optimization of Peltier current lead for applied superconducting systems with optimum combination of cryo-stages  

NASA Astrophysics Data System (ADS)

The reduction of electric power consumption of the cryo-cooler during the working conditions of applied superconducting systems is important, as superconductivity can only be stored at low temperature and the power required for the cooling determines the efficiency of the systems employed. Use of Peltier current leads (PCLs) represents one key solution to effect heat load reduction on the terminals in systems. On the other hand, the performance of cryo-coolers generally increases as the temperature increases given the higher Carnot efficiency. Therefore, combination with suitable mid-stage temperatures represents one possible approach since the thermal anchor can enhance the performance of the system by reducing the electric power consumption of the cryo-coolers. In this paper, we discuss this possibility utilizing an advanced configuration of PCL with a commercially available high temperature cooler. Over 50% enhancement of the performance is estimated.

Kawahara, Toshio; Emoto, Masahiko; Watanabe, Hirofumi; Hamabe, Makoto; Sun, Jian; Ivanov, Yury; Yamaguchi, Satarou

2012-06-01

407

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

408

Studies of sheath characteristics in a double plasma device with a negatively biased separating grid and a magnetic filter field  

SciTech Connect

A double plasma device has two regions: Source region and target region. These two regions are divided by a magnetic filter field. A grid is placed coplanar to the magnetic filter. To study the sheath structure in the target region, a metallic plate is placed at the center, which can be biased with respect to the chamber (ground) potential. Plasma is created in the source region by filament discharge technique. Plasma diffusing from the source region to the target region is subjected to the magnetic filter field and also an electric field applied on the grid. Plasma thus obtained in the target region forms a sheath on the biased plate. The influence of both the magnetic filter field and the electric field, applied between the grid and the chamber wall, on the sheath structure formed on the biased plate is studied. It is found that the magnetic filter field and the electric field change the sheath structure in different ways.

Das, B. K.; Chakraborty, M. [Centre of Plasma Physics-Institute for Plasma Research, Tepesia, Sonapur, Kamrup, Assam-782402 (India); Bandyopadhyay, M. [ITER-India, Institute for Plasma Research, Bhat, Gandhinagar, Gujarat-382428 (India)

2012-09-15

409

Electronic phase separation due to magnetic polaron formation in the semimetallic ferromagnet EuB6 — A weakly-nonlinear-transport study  

NASA Astrophysics Data System (ADS)

We report measurements of weakly nonlinear electronic transport, as measured by third-harmonic voltage generation V 3?, in the low-carrier density semimetallic ferromagnet EuB6, which exhibits an unusual magnetic ordering with two consecutive transitions at T_{c_1 } = 15.6K and T_{c_2 } = 12.5K. In contrast to the linear resistivity, the third-harmonic voltage is sensitive to the microgeometry of the electronic system. Our measurements provide evidence for magnetically-driven electronic phase separation consistent with the picture of percolation of magnetic polarons (MP), which form highly conducting magnetically ordered clusters in a paramagnetic and less conducting background. Upon cooling in zero magnetic field through the ferromagnetic transition, the dramatic drop in the linear resistivity at the upper transition T_{c_1 } coincides with the onset of nonlinearity, and upon further cooling is followed by a pronounced peak in V 3? at the lower transition T_{c_2 } . Likewise, in the paramagnetic regime, a drop of the material's magnetoresistance R( H) precedes a magnetic-fieldinduced peak in nonlinear transport. A striking observation is a linear temperature dependence of V {3?/peak}. We suggest a picture where at the upper transition T_{c_1 } the coalescing MP form a conducting path giving rise to a strong decrease in the resistance. The MP formation sets in at around T* ˜ 35K below which these entities are isolated and strongly fluctuating, while growing in number. The MP then start to form links at T_{c_1 } , where percolative electronic transport is observed. The MP merge and start forming a continuum at the threshold T_{c_2 } . In the paramagnetic temperature regime T_{c_1 } < T < T*, MP percolation is induced by a magnetic field, and the threshold accompanied by charge carrier delocalization occurs at a single critical magnetization.

Amyan, Adham; Das, Pintu; Müller, Jens; Fisk, Zachary

2013-05-01

410

Separation of magnetic properties at uranium and cobalt sites in UCoAl using soft x-ray magnetic circular dichroism  

NASA Astrophysics Data System (ADS)

Temperature (T) and magnetic field (H) dependence of the magnetic properties in metamagnetic UCoAl have been investigated using a soft x-ray magnetic circular dichroism (XMCD). In order to extract element-specific magnetic properties at the U and Co sites, the XMCD experiment has been performed at the U 4d-5f (N4,5) and Co 2p-3d (L2,3) absorption edges, respectively. Directions of magnetic moments at the U and Co sites have been determined from shapes of the XMCD spectra. The directions of the total magnetic moments at the U and Co sites are parallel to the H direction (c axis), but the direction of the spin magnetic moment at the U site is opposite to that at the Co site. The XMCD intensities at both the U and Co sites at T=5.5 K increase steeply at H=0.77 T (Hm), corresponding to the metamagnetic transition. The XMCD intensities do not saturate, even in the field-induced ferromagnetic state above Hm. In addition, the ratio of the increase of the XMCD intensity at the Co site is smaller than that at the U site. From comparison of the H dependence of the XMCD intensities at T=25 and 5.5 K, we found that the magnetic behavior of the Co atom has a stronger T dependence than that of the U atom.

Takeda, Yukiharu; Saitoh, Yuji; Okane, Tetsuo; Yamagami, Hiroshi; Matsuda, Tatsuma D.; Yamamoto, Etsuji; Haga, Yoshinori; ?nuki, Yoshichika; Fisk, Zachary