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1

[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

2

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

3

Fiber Bragg Grating Cryo-Sensors for Superconducting Accelerator Magnets  

E-print Network

The design, fabrication and tests of the new generation of superconducting magnets for the High Luminosity upgrade of the Large Hadron Collider (HL - LHC) require the support of an adequate sensing technology able to assure the integrity of the strain sensitive and brittle superconducting cables through the whole service life of the magnet: assembly up to 150 MPa, cool down to 1.9 K and powering up to about 16 kA. A precise temperature monitoring is also needed in order to guarantee the safe working condition of the superconducting cables in the power transmission lines (SC - Link) designed to feed the magnet over long distance. Temperature and strain FBGs based monitoring systems have been implemented in the first SC-Link prototype and in two subscale dipole magnets and tested in the cryogenic test facility at CERN at 30 K, 77 K and 1.9 K.

Chiuchiolo, A; Perez, J; Bajas, H; Consales, M; Giordano, M; Breglio, G; Cusano, A

2014-01-01

4

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

5

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

6

The physics of magnetic separation  

NASA Astrophysics Data System (ADS)

Current activity in the field of magnetic separation is reviewed in fundamental terms. The diverse subject matter is ordered into four main groupings whose characteristics are described in terms of numerous devices, both of present-day and historical significance. Existing as well as potential areas of scientific and commercial operation are discussed. The basic principles of recent major developments in high intensity magnetic separation are closely examined.

Parker, M. R.

1977-05-01

7

Magnetic particle separation using controllable magnetic force switches  

NASA Astrophysics Data System (ADS)

Magnetic particle separation is very important in biomedical applications. In this study, a magnetic particle microseparator is proposed that uses micro magnets to produce open/closed magnetic flux for switching on/off the separation. When all magnets are magnetized in the same direction, the magnetic force switch for separation is on; almost all magnetic particles are trapped in the channel side walls and the separation rate can reach 95%. When the magnetization directions of adjacent magnets are opposite, the magnetic force switch for separation is off, and most magnetic particles pass through the microchannel without being trapped. For the separation of multi-sized magnetic particles, the proposed microseparator is numerically demonstrated to have high separation rate.

Wei, Zung-Hang; Lee, Chiun-Peng; Lai, Mei-Feng

2010-01-01

8

Method of magnetic separation and apparatus therefore  

NASA Technical Reports Server (NTRS)

An apparatus for magnetically separating and collecting particulate matter fractions of a raw sample according to relative magnetic susceptibilities of each fraction so collected is disclosed. The separation apparatus includes a splitter which is used in conjunction with a magnetic separator for achieving the desired fractionation.

Oder, Robin R. (Inventor)

1991-01-01

9

Whole Mouse Cryo-Imaging  

PubMed Central

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. PMID:19756215

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

2009-01-01

10

Magnetic separation techniques: their application to medicine  

Microsoft Academic Search

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

J. T. Kemsheadl; J. Ugelstad

1985-01-01

11

Magnetically Enhanced Solid-Liquid Separation  

Microsoft Academic Search

DuPont is developing an entirely new method of solid-liquid filtration involving the use of magnetic fields and magnetic field gradients. The new hybrid process, entitled Magnetically Enhanced Solid-Liquid Separation (MESLS), is designed to improve the de-watering kinetics and reduce the residual moisture content of solid particulates mechanically separated from liquid slurries. Gravitation, pressure, temperature, centrifugation, and fluid dynamics have dictated

C. M. Rey; K. Keller; B. Fuchs

2005-01-01

12

Magnetic separation in water pollution control  

Microsoft Academic Search

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

CHRISTOPHER DE LATOUR

1973-01-01

13

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

14

Magnetically Enhanced Solid-Liquid Separation  

NASA Astrophysics Data System (ADS)

DuPont is developing an entirely new method of solid-liquid filtration involving the use of magnetic fields and magnetic field gradients. The new hybrid process, entitled Magnetically Enhanced Solid-Liquid Separation (MESLS), is designed to improve the de-watering kinetics and reduce the residual moisture content of solid particulates mechanically separated from liquid slurries. Gravitation, pressure, temperature, centrifugation, and fluid dynamics have dictated traditional solid-liquid separation for the past 50 years. The introduction of an external field (i.e. the magnetic field) offers the promise to manipulate particle behavior in an entirely new manner, which leads to increased process efficiency. Traditional solid-liquid separation typically consists of two primary steps. The first is a mechanical step in which the solid particulate is separated from the liquid using e.g. gas pressure through a filter membrane, centrifugation, etc. The second step is a thermal drying process, which is required due to imperfect mechanical separation. The thermal drying process is over 100-200 times less energy efficient than the mechanical step. Since enormous volumes of materials are processed each year, more efficient mechanical solid-liquid separations can be leveraged into dramatic reductions in overall energy consumption by reducing downstream drying requirements have a tremendous impact on energy consumption. Using DuPont's MESLS process, initial test results showed four very important effects of the magnetic field on the solid-liquid filtration process: 1) reduction of the time to reach gas breakthrough, 2) less loss of solid into the filtrate, 3) reduction of the (solids) residual moisture content, and 4) acceleration of the de-watering kinetics. These test results and their potential impact on future commercial solid-liquid filtration is discussed. New applications can be found in mining, chemical and bioprocesses.

Rey, C. M.; Keller, K.; Fuchs, B.

2005-07-01

15

Particle acceleration at a reconnecting magnetic separator  

NASA Astrophysics Data System (ADS)

Context. While the exact acceleration mechanism of energetic particles during solar flares is (as yet) unknown, magnetic reconnection plays a key role both in the release of stored magnetic energy of the solar corona and the magnetic restructuring during a flare. Recent work has shown that special field lines, called separators, are common sites of reconnection in 3D numerical experiments. To date, 3D separator reconnection sites have received little attention as particle accelerators. Aims: We investigate the effectiveness of separator reconnection as a particle acceleration mechanism for electrons and protons. Methods: We study the particle acceleration using a relativistic guiding-centre particle code in a time-dependent kinematic model of magnetic reconnection at a separator. Results: The effect upon particle behaviour of initial position, pitch angle, and initial kinetic energy are examined in detail, both for specific (single) particle examples and for large distributions of initial conditions. The separator reconnection model contains several free parameters, and we study the effect of changing these parameters upon particle acceleration, in particular in view of the final particle energy ranges that agree with observed energy spectra.

Threlfall, J.; Neukirch, T.; Parnell, C. E.; Eradat Oskoui, S.

2015-02-01

16

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

17

Dual Magnetic Separator for TRI$?$P  

E-print Network

The TRI$\\mu$P facility, under construction at KVI, requires the production and separation of short-lived and rare isotopes. Direct reactions, fragmentation and fusion-evaporation reactions in normal and inverse kinematics are foreseen to produce nuclides of interest with a variety of heavy-ion beams from the superconducting cyclotron AGOR. For this purpose, we have designed, constructed and commissioned a versatile magnetic separator that allows efficient injection into an ion catcher, i.e., gas-filled stopper/cooler or thermal ionizer, from which a low energy radioactive beam will be extracted. The separator performance was tested with the production and clean separation of $^{21}$Na ions, where a beam purity of 99.5% could be achieved. For fusion-evaporation products, some of the features of its operation as a gas-filled recoil separator were tested.

G. P. A. Berg; O. C. Dermois; U. Dammalapati; P. Dendooven M. N. Harakeh; K. Jungmann; C. J. G. Onderwater; A. Rogachevskiy; M. Sohani; E. Traykov; L. Willmann; H. W. Wilschut

2006-01-16

18

Multistage Magnetic Separator of Cells and Proteins  

NASA Technical Reports Server (NTRS)

The multistage electromagnetic separator for purifying cells and magnetic particles (MAGSEP) is a laboratory apparatus for separating and/or purifying particles (especially biological cells) on the basis of their magnetic susceptibility and magnetophoretic mobility. Whereas a typical prior apparatus based on similar principles offers only a single stage of separation, the MAGSEP, as its full name indicates, offers multiple stages of separation; this makes it possible to refine a sample population of particles to a higher level of purity or to categorize multiple portions of the sample on the basis of magnetic susceptibility and/or magnetophoretic mobility. The MAGSEP includes a processing unit and an electronic unit coupled to a personal computer. The processing unit includes upper and lower plates, a plate-rotation system, an electromagnet, an electromagnet-translation system, and a capture-magnet assembly. The plates are bolted together through a roller bearing that allows the plates to rotate with respect to each other. An interface between the plates acts as a seal for separating fluids. A lower cuvette can be aligned with as many as 15 upper cuvette stations for fraction collection during processing. A two-phase stepping motor drives the rotation system, causing the upper plate to rotate for the collection of each fraction of the sample material. The electromagnet generates a magnetic field across the lower cuvette, while the translation system translates the electromagnet upward along the lower cuvette. The current supplied to the electromagnet, and thus the magnetic flux density at the pole face of the electromagnet, can be set at a programmed value between 0 and 1,400 gauss (0.14 T). The rate of translation can be programmed between 5 and 2,000 m/s so as to align all sample particles in the same position in the cuvette. The capture magnet can be a permanent magnet. It is mounted on an arm connected to a stepping motor. The stepping motor rotates the arm to position the capture magnet above the upper cuvette into which a fraction of the sample is collected. The electronic unit includes a power switch, power-supply circuitry that accepts 110-Vac input power, an RS-232 interface, and status lights. The personal computer runs the MAGSEP software and controls the operation of the MAGSEP through the RS-232 interface. The status of the power, the translating electromagnet, the capture magnet, and the rotation of the upper plate are indicated in a graphical user interface on the computer screen.

Barton, Ken; Ainsworth, Mark; Daily, Bruce; Dunn, Scott; Metz, Bill; Vellinger, John; Taylor, Brock; Meador, Bruce

2005-01-01

19

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 PMID:8118790

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

1994-01-01

20

A Parametric Study of a Portable Magnetic Separator for Separation of Nanospheres from Circulatory System  

Microsoft Academic Search

A portable magnetic separator was proposed for in-vivo biomedical applications. In this prototype design, a matrix of alternating, parallel magnetizable wires, and biocompatible tubing is immersed into an externally applied magnetic field. The wires are magnetized and high magnetic fields as well as field gradients are created to trap blood-borne flowing magnetic nanospheres in the tube. In this paper, a

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

2010-01-01

21

Creation of superconducting magnet separators for weakly magnetic mineral raw material processing  

SciTech Connect

The paper describes the investigations to work out the design and process parameters of superconducting commercial separators using laboratory units. The design features of the magnet system and the cryostat of the separator of the disk type for wet separation of weakly magnetic ores and non-ore materials are presented. The results of modelling the technological flowsheets for separation of various types of weakly magnetic material using SC magnetic separators are given. The necessity to further improve the magnetic separators in the direction of generation of the magnetic flux higher magnetic forces and densities is well-grounded.

Sidorenko, V.D.; Gerasimenko, I.A.; Kutin, A.M. [Mekhanobrchermet Inst., Krivoy Rog (Ukraine)] [Mekhanobrchermet Inst., Krivoy Rog (Ukraine); Yupherov, V.B.; Skibenko, Y.I. [National Research Centre Kharkov Physico-Technical Inst. (Ukraine)] [National Research Centre Kharkov Physico-Technical Inst. (Ukraine); Gladky, V.V. [Inst. of Low Temperature Physics and Engineering, Kharkov (Ukraine)] [Inst. of Low Temperature Physics and Engineering, Kharkov (Ukraine)

1996-07-01

22

MSWI boiler fly ashes: magnetic separation for material recovery.  

PubMed

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

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

2011-07-01

23

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

24

A feasibility study of magnetic separation of magnetic nanoparticle for forward osmosis.  

PubMed

It was recently reported that a UK company has developed a naturally non-toxic magnetoferritin to act as a draw solute for drawing water in forward osmosis process. The gist of this technology is the utilization of the magnetic nanoparticle and high-gradient magnetic separation for draw solute separation and reuse. However, any demonstration on this technology has not been reported yet. In this study, a feasibility test of magnetic separation using magnetic nanoparticle was therefore performed to investigate the possibility of magnetic separation in water treatment such as desalination. Basically, a magnetic separation system consisted of a column packed with a bed of magnetically susceptible wools placed between the poles of electromagnet and Fe3O4 magnetic nanoparticle was used as a model nanoparticle. The effect of nanoparticle size to applied magnetic field in separation column was experimentally investigated and the magnetic field distribution in a magnet gap and the magnetic field gradient around stainless steel wool wire were analyzed through numerical simulation. The amount of magnetic nanoparticle captured in the separator column increased as the magnetic field strength and particle size increased. As a result, if magnetic separation is intended to be used for draw solute separation and reuse, both novel nanoparticle and large-scale high performance magnetic separator must be developed. PMID:22097022

Kim, Y C; Han, S; Hong, S

2011-01-01

25

SEPARATION OF VARIABLES AND THE XXZ GAUDIN MAGNET  

E-print Network

SEPARATION OF VARIABLES AND THE XXZ GAUDIN MAGNET E.G. KALNINS, V.B. KUZNETSOV and WILLARD MILLER, Minnesota 55455, USA. Abstract. In this work we generalise previous results connecting (rational) Gaudin the relationship between the separable systems and the Gaudin magnet [4,9] integrable systems models has been

Miller, Willard

26

Microfluidic high gradient magnetic cell separation David W. Inglisa  

E-print Network

and by the selective attachment of magnetic beads has recently been demonstrated on microfluidic devices. We discuss microfluidic devices for the magnetic separation of blood cells. We also discuss our attempts to integrate. © 2006 American Institute of Physics. DOI: 10.1063/1.2165782 INTRODUCTION Cell separation by centrifuge

27

Magnetic separation of micro-spheres from viscous biological fluids  

NASA Astrophysics Data System (ADS)

A magnetically based detoxification system is being developed as a therapeutic tool for selective and rapid removal of biohazards, i.e. chemicals and radioactive substances, from human blood. One of the key components of this system is a portable magnetic separator capable of separating polymer-based magnetic nano/micro-spheres from arterial blood flow in an ex vivo unit. The magnetic separator consists of an array of alternating and parallel capillary tubing and magnetizable wires, which is exposed to an applied magnetic field created by two parallel permanent magnets such that the magnetic field is perpendicular to both the wires and the fluid flow. In this paper, the performance of this separator was evaluated via preliminary in vitro flow experiments using a separator unit consisting of single capillary glass tubing and two metal wires. Pure water, ethylene glycol-water solution (v:v = 39:61 and v:v = 49:51) and human whole blood were used as the fluids. The results showed that when the viscosity increased from 1.0 cp to 3.0 cp, the capture efficiency (CE) decreased from 90% to 56%. However, it is still feasible to obtain >90% CE in blood flow if the separator design is optimized to create higher magnetic gradients and magnetic fields in the separation area.

Chen, Haitao; Kaminski, Michael D.; Caviness, Patricia L.; Xianqiao, Liu; Dhar, Promila; Torno, Michael; Rosengart, Axel J.

2007-02-01

28

Magnetic separation of micro-spheres from viscous biological fluids.  

SciTech Connect

A magnetically based detoxification system is being developed as a therapeutic tool for selective and rapid removal of biohazards, i.e. chemicals and radioactive substances, from human blood. One of the key components of this system is a portable magnetic separator capable of separating polymer-based magnetic nano/micro-spheres from arterial blood flow in an ex vivo unit. The magnetic separator consists of an array of alternating and parallel capillary tubing and magnetizable wires, which is exposed to an applied magnetic field created by two parallel permanent magnets such that the magnetic field is perpendicular to both the wires and the fluid flow. In this paper, the performance of this separator was evaluated via preliminary in vitro flow experiments using a separator unit consisting of single capillary glass tubing and two metal wires. Pure water, ethylene glycol-water solution (v:v = 39:61 and v:v = 49:51) and human whole blood were used as the fluids. The results showed that when the viscosity increased from 1.0 cp to 3.0 cp, the capture efficiency (CE) decreased from 90% to 56%. However, it is still feasible to obtain >90% CE in blood flow if the separator design is optimized to create higher magnetic gradients and magnetic fields in the separation area.

Chen, H.; Kaminski, M. D.; Xianqiao, L.; Caviness, P.; Torno, M.; Rosengart, A. J.; Dhar, P.; Chemical Engineering; Univ. of Chicago Pritzker School of Medicine; Illinois Inst. of Tech.

2007-02-21

29

Magnetically separable composite photocatalyst with enhanced photocatalytic activity.  

PubMed

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

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

2008-12-30

30

Magnetic-based microfluidic platform for biomolecular separation.  

PubMed

A novel microfluidic platform for manipulation of micro/nano magnetic particles was designed, fabricated and tested for applications dealing with biomolecular separation. Recently, magnetic immunomagnetic cell separation has attracted a noticeable attention due to the high selectivity of such separation methods. Strong magnetic field gradients can be developed along the entire wire, and the miniaturized size of these current-carrying conductors strongly enhances the magnetic field gradient and therefore produces large, tunable and localized magnetic forces that can be applied on magnetic particles and confine them in very small spots. Further increases in the values of the generated magnetic field gradients can be achieved by employing miniaturized ferromagnetic structures (pillars) which can be magnetized by an external magnetic field or by micro-coils on the same chip. In this study, we demonstrate magnetic beads trapping, concentration, transportation and sensing in a liquid sample under continuous flow by employing high magnetic field gradients generated by novel multi-functional magnetic micro-devices. Each individual magnetic micro-device consists of the following components: 1. Cu micro-coils array embedded in the silicon substrate with high aspect ratio conductors for efficient magnetic field generation 2. Magnetic pillar(s) made of the magnetic alloy NiCoP for magnetic field focusing and magnetic field gradient enhancement. Each pillar is magnetized by its corresponding coil 3. Integrated sensing coil for magnetic beads detection 4. Microfluidic chamber containing all the previous components. Magnetic fields of about 0.1 T and field gradients of around 300 T/cm have been achieved, which allowed to develop a magnetic force of 3 x 10(-9) N on a magnetic particle with radius of 1 mum. This force is large enough to trap/move this particle as the required force to affect such particles in a liquid sample is on the order of approximately pN. Trapping rates of up to 80% were achieved. Furthermore, different micro-coil designs were realized which allowed various movement modes and with different step-sizes. These results demonstrate that such devices incorporated within a microfluidic system can provide significantly improved spatial resolution and force magnitude for quick, efficient and highly selective magnetic trapping, separation and transportation, and as such they are an excellent solution for miniaturized mu-total analysis systems. PMID:16688574

Ramadan, Qasem; Samper, Victor; Poenar, Daniel; Yu, Chen

2006-06-01

31

Optimizing colloidal dispersity of magnetic nanoparticles based on magnetic separation with magnetic nanowires array  

NASA Astrophysics Data System (ADS)

Based on sharp geometry of Ni nanowires, we developed a novel high-gradient magnetic separator that was composed of a nanowires array and a uniform magnetic field. When suspension of magnetic nanoparticles (MNPs) flowed through it, the relatively large nanoparticles or clusters were removed from the suspension so that the size distribution can be improved. The separation resulted from magnetic force so that extra molecules or solvents were unnecessary to add. The performance was proved by scanned electron microscopy characterization and dynamic light scattering measurement. The improvement in magnetic colloidal dispersivity is important for the biomedical application of MNPs. Our results may also play a role in microfluidic application and nanoparticle-based detection.

Sun, Jianfei; He, Miaomiao; Liu, Xuan; Gu, Ning

2014-09-01

32

Optimizing colloidal dispersity of magnetic nanoparticles based on magnetic separation with magnetic nanowires array  

NASA Astrophysics Data System (ADS)

Based on sharp geometry of Ni nanowires, we developed a novel high-gradient magnetic separator that was composed of a nanowires array and a uniform magnetic field. When suspension of magnetic nanoparticles (MNPs) flowed through it, the relatively large nanoparticles or clusters were removed from the suspension so that the size distribution can be improved. The separation resulted from magnetic force so that extra molecules or solvents were unnecessary to add. The performance was proved by scanned electron microscopy characterization and dynamic light scattering measurement. The improvement in magnetic colloidal dispersivity is important for the biomedical application of MNPs. Our results may also play a role in microfluidic application and nanoparticle-based detection.

Sun, Jianfei; He, Miaomiao; Liu, Xuan; Gu, Ning

2015-02-01

33

Microstripes for transport and separation of magnetic particles  

PubMed Central

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

2012-01-01

34

Electron spin separation without magnetic field.  

PubMed

A nanodevice capable of separating spins of two electrons confined in a quantum dot formed in a gated semiconductor nanowire is proposed. Two electrons confined initially in a single quantum dot in the singlet state are transformed into the system of two electrons confined in two spatially separated quantum dots with opposite spins. In order to separate the electrons' spins we exploit transitions between the singlet and the triplet state, which are induced by resonantly oscillating Rashba spin-orbit coupling strength. The proposed device is all electrically controlled and the electron spin separation can be realized within tens of picoseconds. The results are supported by solving numerically the quasi-one-dimensional time-dependent Schroedinger equation for two electrons, where the electron-electron correlations are taken into account in the exact manner. PMID:25106038

Paw?owski, J; Szumniak, P; Skubis, A; Bednarek, S

2014-08-27

35

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

36

Emerging magnetism and electronic phase separation at titanate interfaces  

NASA Astrophysics Data System (ADS)

The emergence of magnetism in otherwise nonmagnetic compounds and its underlying mechanisms have become the subject of intense research. Here we demonstrate that the nonmagnetic oxygen vacancies are responsible for an unconventional magnetic state common for titanate interfaces and surfaces. Using an effective multiorbital modeling, we find that the presence of localized vacancies leads to an interplay of ferromagnetic order in the itinerant t2g band and complex magnetic oscillations in the orbitally reconstructed eg band, which can be tuned by gate fields at oxide interfaces. The magnetic phase diagram includes highly fragmented regions of stable and phase-separated magnetic states forming beyond nonzero critical defect concentrations.

Pavlenko, N.; Kopp, T.; Mannhart, J.

2013-11-01

37

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

38

Application of high temperature superconductors to high-gradient magnetic separation  

Microsoft Academic Search

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

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

1994-01-01

39

Development of magnetic separation methods of analysis: magnetic field flow fractionation  

E-print Network

DEVELOPMENT OF MAGNETIC SEPARATION METHODS OF ANALYSIS: MAGNETIC FIELD FLOW FRACTIONATION A Thesis by JAIME GARCIA-RAMIREZ Submitted to the Graduate College of Texas A&M University in partial fulfillment of the requirement for the degree... of MASTER OF SCIENCE August 1980 Major Subject: Chemistry DEVELOPMENT OF MAGNETIC SEPARATION METHODS OF ANALYSIS: MAGNETIC FIELD FLOW FRACTIONATION A Thesis by JAIME GARCIA-RAMIREZ Approved as to style and content by: (Chairman of Committee) 1...

Garcia-Ramirez, Jaime

2012-06-07

40

Use of high gradient magnetic separation for actinide application  

SciTech Connect

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

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

1996-08-01

41

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

PubMed

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 due to adhesion. To compare separation efficiency between the MACS and the DMACS, the total number of cells before and after separation with both the separators was counted by flow cytometry. We could find that the number (3241/59 940) of cells lost in the DMACS is much less than that (22 360/59 940) in the MACS while the efficiency of cell separation in the DMACS (96.07%) is almost the same as that in the MACS (96.72%). Practically, with fluorescent images, it was visually confirmed that the statistical data are reliable. From the viability test by using Hoechst 33 342, it was also demonstrated that there was no cell damage on a gas-liquid interface. Conclusively, DMACS will be a powerful tool to separate rare cells and applicable as a separator, key component of lab-on-a-chip. PMID:17672779

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

2007-07-01

42

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

NASA Astrophysics Data System (ADS)

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 due to adhesion. To compare separation efficiency between the MACS and the DMACS, the total number of cells before and after separation with both the separators was counted by flow cytometry. We could find that the number (3241/59940) of cells lost in the DMACS is much less than that (22360/59940) in the MACS while the efficiency of cell separation in the DMACS (96.07%) is almost the same as that in the MACS (96.72%). Practically, with fluorescent images, it was visually confirmed that the statistical data are reliable. From the viability test by using Hoechst 33 342, it was also demonstrated that there was no cell damage on a gas-liquid interface. Conclusively, DMACS will be a powerful tool to separate rare cells and applicable as a separator, key component of lab-on-a-chip.

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

2007-07-01

43

Modeling high gradient magnetic separation from biological fluids.  

SciTech Connect

A proposed portable magnetic separator consists of an array of biocompatible capillary tubing and magnetizable wires immersed in an externally applied homogeneous magnetic field. While subject to the homogeneous magnetic field, the wires create high magnetic field gradients, which aid in the collection of blood-borne magnetic nanospheres from blood flow. In this study, a 3-D numerical model was created using COMSOL Multiphysics 3.2 software to determine the configuration of the wire-tubing array from two possible configurations, one being an array with rows alternating between wires and tubing, and the other being an array where wire and tubing alternate in two directions. The results demonstrated that the second configuration would actually capture more of the magnetic spheres. Experimental data obtained by our group support this numerical result.

Bockenfeld, D.; Chen, H.; Rempfer, D.; Kaminski, M. D.; Rosengart, A. J.; Chemical Engineering; Illinois Inst. of Tech.; Univ. of Chicago, Pritzker School of Medicine

2006-01-01

44

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

45

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

46

Differential magnetic catch and release: Separation, purification, and characterization of magnetic nanoparticles and particle assemblies  

NASA Astrophysics Data System (ADS)

Magnetic nanoparticles uniquely combine superparamagnetic behavior with dimensions that are smaller than or the same size as molecular analytes. The integration of magnetic nanoparticles with analytical methods has opened new avenues for sensing, purification, and quantitative analysis. Applied magnetic fields can be used to control the motion and properties of magnetic nanoparticles; in analytical chemistry, use of magnetic fields provides methods for manipulating and analyzing species at the molecular level. The ability to use applied magnetic fields to control the motion and properties of magnetic nanoparticles is a tool for manipulating and analyzing species at the molecular level, and has led to applications including analyte handing, chemical sensors, and imaging techniques. This is clearly an area where significant growth and impact in separation science and analysis is expected in the future. In Chapter 1, we describe applications of magnetic nanoparticles to analyte handling, chemical sensors, and imaging techniques. Chapter 2 reports the purification and separation of magnetic nanoparticle mixtures using the technique developed in our lab called 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 density and experimentally determined force required to trap 50% of the particle sample. Balancing the relative strengths of the drag and magnetic forces enable separation and purification of magnetic CoFe2 O4 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. Differential magnetic catch and release has been used as a method for the purification and separation of magnetic nanoparticles. In Chapter 3 the separation metrics are reported. DMCR separates nanoparticles in the mobile phase by magnetic trapping of magnetic nanoparticles against the wall of an open tubular capillary wrapped between two narrowly spaced electromagnetic poles. Using Au and CoFe2O4 nanoparticles as model systems, the loading capacity of the 250 microm diameter capillary is determined to be ˜130 microg, and is scalable to higher quantities with larger bore capillary. Peak resolution in DMCR is externally controlled by selection of the release time (Rt) at which the magnetic flux density is removed, however longer capture times are shown to reduce the capture yield. In addition, the magnetic nanoparticle capture yields are observed to depend on the nanoparticle diameter, mobile phase viscosity and velocity, and applied magnetic flux. Using these optimized parameters, three samples of CoFe 2O4 nanoparticles whose diameters are different by less than 10 nm are separated with excellent resolution and capture yield, demonstrating the capability of DMCR for separation and purification of magnetic nanoparticles. Individual hybrid nanocrystals possess multiple structural units with solid state interfaces, giving them a wide range of possible applications. Synthesis of truly monodisperse nanoparticles and hybrid nanocrystals is a formidable task, which has led us to apply our analytical technique, differential magnetic catch and release, to separate and purify magnetic nanoparticles. Using an open tubular capillary column and electromagnet, DMCR separates magnetic nanoparticles based on a balance of their magnetic moment and hydrodynamic size. Chapter 4 focuses on the purification of real world samples of hybrid nanocrystals including Au-Fe3O4 heterostructures and FePt-Fe3O4 dimers. Samples are characterized with transmission electron microscopy, UV-Vis, X-ray diffraction spectroscopy, selected area electro

Beveridge, Jacob S.

47

Rapid and continuous magnetic separation in droplet microfluidic devices.  

PubMed

We present a droplet microfluidic method to extract molecules of interest from a droplet in a rapid and continuous fashion. We accomplish this by first marginalizing functionalized super-paramagnetic beads within the droplet using a magnetic field, and then splitting the droplet into one droplet containing the majority of magnetic beads and one droplet containing the minority fraction. We quantitatively analysed the factors which affect the efficiency of marginalization and droplet splitting to optimize the enrichment of magnetic beads. We first characterized the interplay between the droplet velocity and the strength of the magnetic field and its effect on marginalization. We found that marginalization is optimal at the midline of the magnet and that marginalization is a good predictor of bead enrichment through splitting at low to moderate droplet velocities. Finally, we focused our efforts on manipulating the splitting profile to improve the enrichment provided by asymmetric splitting. We designed asymmetric splitting forks that employ capillary effects to preferentially extract the bead-rich regions of the droplets. Our strategy represents a framework to optimize magnetic bead enrichment methods tailored to the requirements of specific droplet-based applications. We anticipate that our separation technology is well suited for applications in single-cell genomics and proteomics. In particular, our method could be used to separate mRNA bound to poly-dT functionalized magnetic microparticles from single cell lysates to prepare single-cell cDNA libraries. PMID:25501881

Brouzes, Eric; Kruse, Travis; Kimmerling, Robert; Strey, Helmut H

2015-01-22

48

Pair separation of magnetic elements in the quiet Sun  

NASA Astrophysics Data System (ADS)

The dynamic properties of the quiet Sun photosphere can be investigated by analyzing the pair dispersion of small-scale magnetic fields (i.e., magnetic elements). By using 25 h-long Hinode magnetograms at high spatial resolution (0.3 arcsec), we tracked 68 490 magnetic element pairs within a supergranular cell near the disk center. The computed pair separation spectrum, calculated on the whole set of particle pairs independently of their initial separation, points out what is known as a super-diffusive regime with spectral index ? = 1.55 ± 0.05, in agreement with the most recent literature, but extended to unprecedented spatial and temporal scales (from granular to supergranular). Furthermore, for the first time, we investigated here the spectrum of the mean square displacement of pairs of magnetic elements, depending on their initial separation r0. We found that there is a typical initial distance above (below) which the pair separation is faster (slower) than the average. A possible physical interpretation of such a typical spatial scale is also provided.

Giannattasio, F.; Berrilli, F.; Biferale, L.; Del Moro, D.; Sbragaglia, M.; Bellot Rubio, L.; Goši?, M.; Orozco Suárez, D.

2014-09-01

49

Magnetic separation as a plutonium residue enrichment process  

SciTech Connect

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

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

1989-01-01

50

Coil geometry for efficient active compensation with separated magnetic shields  

NASA Astrophysics Data System (ADS)

We have already proposed a new method of magnetic shielding aiming for magnetocardiography, in which magnetic shells are separated and a new compensation scheme is employed to allow for wide space between them. Each magnetic shell that consists of a half of the cylinder (diameter=20 cm and length=60 cm) and two flanges at both ends of the half cylinder extending along the radial direction has a saddle coil on its outer surface with the coil's long straight section running parallel to the axis of the cylinder. In this paper, the relationship between the width of the long straight sections of the saddle coil and the efficiency of the active compensation is investigated by the finite element method (FEM) analysis and by experiments. A magnetic shield used in this study is a double shell structure where each shell is made of stacked amorphous tapes and the outer shell has a magnetic shaking coil for the enhancement of the permeability. We have found that for a given magnetic field, the compensation current necessary for a given magnetic field varies by a factor of 3 depending on the width of a saddle coil and that its value monotonically decreases with increasing the width. We have also confirmed that the phase delay of the compensation magnetic field experienced while it comes in the magnetic shell is small.

Nakashima, Yoshihiro; Sasada, Ichiro

2009-04-01

51

Magnetic Separations with Magnetite: Theory, Operation, and Limitations  

SciTech Connect

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

G. B. Cotten

2000-08-01

52

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

NASA Astrophysics Data System (ADS)

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

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

2013-01-01

53

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

54

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

55

Magnetic nano-sorbents for fast separation of radioactive waste  

SciTech Connect

In order to find a cost effective and environmentally benign technology to treat the liquid radioactive waste into a safe and stable form for resource recycling or ultimate disposal, this study investigates the separation of radioactive elements from aqueous systems using magnetic nano-sorbents. Our current study focuses on novel magnetic nano-sorbents by attaching DTPA molecules onto the surface of double coated magnetic nanoparticles (dMNPs), and performed preliminary sorption tests using heavy metal ions as surrogates for radionuclides. The results showed that the sorption of cadmium (Cd) and lead (Pb) onto the dMNP-DTPA conjugates was fast, the equilibrium was reached in 30 min. The calculated sorption capacities were 8.06 mg/g for Cd and 12.09 mg/g for Pb. After sorption, the complex of heavy elements captured by nano-sorbents can be easily manipulated and separated from solution in less than 1 min by applying a small external magnetic field. In addition, the sorption results demonstrate that dMNP-DTPA conjugates have a very strong chelating power in highly diluted Cd and Pb solutions (1-10 ?g/L). Therefore, as a simple, fast, and compact process, this separation method has a great potential in the treatment of high level waste with low concentration of transuranic elements compared to tradition nuclear waste treatment. (authors)

Zhang, Huijin [Environmental Science Program, University of Idaho, Moscow, ID 83844 (United States); Kaur, Maninder [Department of Physics, University of Idaho, Moscow, ID 83844 (United States); Qiang, You [Environmental Science Program, University of Idaho, Moscow, ID 83844 (United States); Department of Physics, University of Idaho, Moscow, ID 83844 (United States)

2013-07-01

56

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

57

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

58

Filter Capacity Predictions for the Capture of Magnetic Microparticles by High-Gradient Magnetic Separation  

Microsoft Academic Search

We present experimental and theoretical methods to predict maximum and working filter capacities for the capture of superparamagnetic microparticles through high-gradient magnetic separation (HGMS). For this, we employed various combinations of nine different HGMS filter matrices and two types of superparamagnetic microparticles. By calculating the separated particle mass per filter mesh area, we clearly demonstrated the influences of wire diameter

Niklas A. Ebner; Cláudia S. G. Gomes; Timothy J. Hobley; Owen R. T. Thomas; Matthias Franzreb

2007-01-01

59

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

E-print Network

at the inlet, turned over, and merged at the outlet to form a laminated layer. For n number of mixer units of a serpentine separation channel and embedded magnetic coils along the channel. Two layers of fluids are introduced at the inlet of the separation channel. The lower layer is the cell mixture, and the upper layer

Kasagi, Nobuhide

60

Separation of variables and the XXZ Gaudin magnet  

E-print Network

In this work we generalise previous results connecting (rational) Gaudin magnet models and classical separation of variables. It is shown that the connection persists for the case of linear r-matrix algebra which corresponds to the trigonometric 4x4 r-matrix (of the XXZ type). We comment also on the corresponding problem for the elliptic (XYZ) r-matrix. A prescription for obtaining integrable systems associated with multiple poles of an L-operator is given.

E. G. Kalnins; V. B. Kuznetsov; Willard Miller, Jr

1994-12-21

61

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

62

Kinetic approach for the purification of nucleotides with magnetic separation.  

PubMed

The isolation of ?-nicotinamide adenine dinucleotide is of great importance since it is widely used in different scientific and technologic fields such as biofuel cells, sensor technology, and hydrogen production. In order to isolate ?-nicotinamide adenine dinucleotide, first 3-aminophenyboronic acid functionalized magnetic nanoparticles were prepared to serve as a magnetic solid support and subsequently they were used for reversible adsorption/desorption of ?-nicotinamide adenine dinucleotide in a batch fashion. The loading capacity of the 3-aminophenyboronic acid functionalized nanoparticles for ?-nicotinamide adenine dinucleotide adsorption was 13.0 ?mol/g. Adsorption kinetic and isotherm studies showed that the adsorption process followed a pseudo-second-order kinetic model and the experimental data can be represented using Langmuir isotherm model. The 3-aminophenyboronic acid functionalized magnetic nanoparticles were proposed as an alternative support for the ?-nicotinamide adenine dinucleotide purification. The results elucidated the significance of magnetic separation as a fast, relatively simple, and low-cost technique. Furthermore, the magnetic supports can be reused at least five times for purification processes. PMID:25199632

Tural, Servet; Tural, Bilsen; Ece, Mehmet ?akir; Yetkin, Evren; Özkan, Necati

2014-11-01

63

Open-gradient Magnetic Separator With Racetrack Coils Suitable for Cleaning Aqueous Solutions  

Microsoft Academic Search

Superconductivity enables magnetic fields in a magnitude of 5-10 times greater than conventional electromagnets. Applied to magnetic separation, use of superconducting magnets opens the possibility to separate sub-micron sized paramagnetic particles. Open-gradient magnetic separation (OGMS) enables continuous operation without the need of matrix-elements. Such a separator consisting of liquid helium cryostat and an Nb3Sn coils were designed and constructed for

Teemu Hartikainen; Risto Mikkonen

2006-01-01

64

CryoSat-2: the CryoSat Recovery Mission  

NASA Astrophysics Data System (ADS)

CryoSat was a mission specifically designed to study the polar ice fields using a radar altimeter. Unlike previous radar altimeter missions there were no compromises introduced to enable multi-disciplinary studies with its data. It was launched on 8 October 2005, but due to a malfunction in the launch vehicle it never reached orbit Instead it crashed into the Arctic ice some 120 km from the North pole, a fitting resting place given the mission goal. Efforts immediately started to secure the possibility to rebuild the satellite and continue the original mission. These efforts have been successful. The member states of the European Space Agency have agreed an implementation plan which will lead to the launch of CryoSat-2 in March 2009. This paper will present the CryoSat Recovery Mission. This will cover the loss of the original CryoSat satellite, pertinent details about the replacement and specifically its scientific payload, planning of the mission and validation activities and finally some implementation and schedule information.

Francis, R.

2006-05-01

65

Cryo Utilities Room Cooling System  

SciTech Connect

Many of the mechanical equipment failures at the Laboratory are due to the loss of cooling water. In order to insure the proper operating temperatures and to increase the reliability of the mechanical equipment in the D0 Cryo Utilities Room it is necessary to provide an independent liquid cooling system. To this end, an enclosed glycoVwater cooling system which transfers heat from two vane-type vacuum pumps and an air compressor to the outside air has been installed in the Cryo Utilities Room. From the appended list it can be seen that only the Thermal Precision PFC-121-D and Ingersoll-Rand WAC 16 deserve closer investigation based on price. The disadvantages of the WAC 16 are that: it runs a little warmer, it requires more valving to properly install a backup pump, inlet and outlet piping are not included, and temperature and pressure indicators are not included. Its only advantage is that it is $818 cheaper than the PFC-121-D. The advantages of the PFC-121-D are that: it has automatic pump switching during shutdown, it has a temperature regulator on one fan control, it has a switch which indicates proper operation, has a sight glass on the expansion tank, and comes with an ASME approved expansion tank and relief valve. For these reasons the Thermal Precision PFC-121-D was chosen. In the past, we have always found the pond water to be muddy and to sometimes contain rocks of greater than 1/2 inch diameter. Thus a system completely dependent on the pond water from the accelerator was deemed unacceptable. A closed system was selected based on its ability to greatly improve reliability, while remaining economical. It is charged with a 50/50 glycol/water mixture capable of withstanding outside temperatures down to -33 F. The fluid will be circulated by a totally enclosed air cooled Thermal Precision PFC-121-D pump. The system will be on emergency power and an automatically controlled backup pump, identical to the primary, is available should the main pump fail. The fan unit is used as a primary cooler and the trim cooler cools the fluid further on extremely hot days. The trim cooler has also been sized to cool the system in the event of a total shutdown provided that the pond water supply has adequate pressure. Due to a broken filter, we found it necessary to install a strainer in the pond water supply line. The expansion tank separates air bubbles, ensures a net positive suction head, protects against surges and over pressurization of the system, and allows for the filling of the system without shutting it off. All piping has been installed, flushed, charged with the glycol/water mix, and hydrostatically tested to 55 psi. The condition of all pumps and flow conditions will be recorded at the PLC. It has been decided not to include the regulator valve in the pond water return line. This valve was designated by the manufacturer to reduce the amount of water flowing through the trim cooler. This is not necessary in our application. There is some concern that the cooling fluid may cool the mechanical eqUipment too much when they are not operating or during very cold days. This issue will be addressed and the conclusion appended to this engineering note.

Ball, G.S.; /Fermilab

1989-01-26

66

Apparatus for magnetic separation of paramagnetic and diamagnetic material  

DOEpatents

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

Doctor, R.D.

1988-10-18

67

Apparatus for magnetic separation of paramagnetic and diamagnetic material  

DOEpatents

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

Doctor, R.D.

1986-07-24

68

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

69

On-chip Magnetic Separation and Cell Encapsulation in Droplets†  

PubMed Central

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 would prevent cross-contamination, provide high recovery yield, and enable study of biological traits at a single cell level. These advantages of on-chip biological experiments is a significant improvement for myriad of cell analyses over conventional methods, which require bulk samples providing only averaged information on cell metabolism. We report on a device that integrates mobile magnetic trap array with microfluidic technology to provide, combined functionality of separation of immunomagnetically labeled cells or magnetic beads and their encapsulation with reagents into pico-liter droplets. This scheme of simultaneous reagent delivery and compartmentalization of the cells immediately after sorting, all performed seamlessly within the same chip, offers unique advantages such as the ability to capture cell traits as originated from its native environment, reduced chance of contamination, minimal use and freshness of the reagent solution that reacts only with separated objects, and tunable encapsulation characteristics independent of the input flow. In addition to the demonstrated preliminary cell viability assay, the device can potentially be integrated with other up- or downstream on-chip modules to become a powerful single-cell analysis tool. PMID:23370785

Chen, Aaron; Byvank, Tom; Chang, Woo-Jin; Bharde, Atul; Vieira, Greg; Miller, Brandon; Chalmers, Jeffrey J.; Bashir, Rashid; Sooryakumar, Ratnasingham

2014-01-01

70

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

71

Primary beneficiation of tantalite using magnetic separation and acid leaching  

NASA Astrophysics Data System (ADS)

Primary beneficiation was successfully performed prior to dissolution of manganotantalite (sample A) and ferrotantalite (sample C) samples obtained from two different mines in the Naquissupa area, Mozambique. Magnetic separation removed the majority of iron and titanium, whereas H2SO4 leaching removed a large portion of thorium and uranium in these samples. Analytical results indicated that 64.14wt% and 72.04wt% of the total Fe and Ti, respectively, and ˜2wt% each of Nb2O5 and Ta2O5 were removed from sample C (ferrotantalite) using the magnetic separation method, whereas only 9.64wt% and 8.66wt% of total Fe2O3 and TiO2, respectively, and ˜2wt% each of Nb2O5 and Ta2O5 were removed from sample A (manganotantalite). A temperature of 50°C and a leaching time of 3 h in the presence of concentrated H2SO4 were observed to be the most appropriate leaching conditions for removal of radioactive elements from the tantalite ores. The results obtained for sample A under these conditions indicated that 64.14wt% U3O8 and 60.77wt% ThO2 were leached into the acidic solution, along with 4.45wt% and 0.99wt% of Nb2O5 and Ta2O5, respectively.

Nete, M.; Koko, F.; Theron, T.; Purcell, W.; Nel, J. T.

2014-12-01

72

Magnetic microgels, a promising candidate for enhanced magnetic adsorbent particles in bioseparation: synthesis, physicochemical characterization, and separation performance.  

PubMed

For specific applications in the field of high gradient magnetic separation of biomaterials, magnetic nanoparticle clusters of controlled size and high magnetic moment in an external magnetic field are of particular interest. We report the synthesis and characterization of magnetic microgels designed for magnetic separation purposes, as well as the separation efficiency of the obtained microgel particles. High magnetization magnetic microgels with superparamagnetic behaviour were obtained in a two-step synthesis procedure by a miniemulsion technique using highly stable ferrofluid on a volatile nonpolar carrier. Spherical clusters of closely packed hydrophobic oleic acid-coated magnetite nanoparticles were coated with cross linked polymer shells of polyacrylic acid, poly-N-isopropylacrylamide, and poly-3-acrylamidopropyl trimethylammonium chloride. The morphology, size distribution, chemical surface composition, and magnetic properties of the magnetic microgels were determined using transmission electron microscopy, X-ray photoelectron spectroscopy, and vibrating sample magnetometry. Magnetically induced phase condensation in aqueous suspensions of magnetic microgels was investigated by optical microscopy and static light scattering. The condensed phase consists of elongated oblong structures oriented in the direction of the external magnetic field and may grow up to several microns in thickness and tens or even hundreds of microns in length. The dependence of phase condensation magnetic supersaturation on the magnetic field intensity was determined. The experiments using high gradient magnetic separation show high values of separation efficiency (99.9-99.97%) for the magnetic microgels. PMID:25519891

Turcu, Rodica; Socoliuc, Vlad; Craciunescu, Izabell; Petran, Anca; Paulus, Anja; Franzreb, Matthias; Vasile, Eugeniu; Vekas, Ladislau

2015-01-21

73

Hybrid magnetic field gradient, rotating wall device for enhanced colloidal magnetic affinity separations  

NASA Astrophysics Data System (ADS)

A 2.0 cm internal diameter 1 m long, axially-rotating horizontal glass tube, with four axially located repeating hybrid magnetic units, is used as part of a flow-through, colloidal magnetic affinity separation device. Each magnetic unit consists of an alternating current solenoid surrounding the chamber followed by four azimuthally distributed permanent magnets that rotate with the chamber. The separation is demonstrated on a model feed system consisting of a mixture of 1.0 ?m diameter biotinylated latex beads (targets) and 9.7 ?m diameter non-functionalized latex beads (non-targets) at a 1:1 number ratio. Two feed flow rates of 12 ml/min and 35 ml/min were used until a total of 600 ml of sample were processed for each. At the low rate we achieved capture efficiency 60%, a separation factor of 18.2 with 95% purity. For the higher flow rate, the capture efficiency was 40%, the separation factor 18.6 with 87% purity. The same device also was used for removal of cadmium ions from a cadmium sulfate solution. Two arrangements for the magnetic units were used. In the first configuration, four hybrid pairs were distributed axially-each pair consisted of an alternating current carrying solenoid, followed by four azimuthally distributed permanent magnets that rotate with the chamber. In the second configuration, all four solenoids were placed first, followed by the four sets of four azimuthally distributed permanent magnets. 1-10 ?m diameter magnetic particles with iron oxide nanoparticles embedded within a quaternary ammonium cellulose matrix (MagaCell- Q, Cortex Biochem) at a starting concentration of 0.5 mg particles/mL were used as the mobile solid support. The feed consisted of a 10.0 mg/L cadmium sulfate solution, at a flow rate of 35 mL/min. For the arrangement, the cadmium concentration at the exit of the third stage dropped to 0.97 mg/L. The second configuration produced a final cadmium concentration of 0.68 mg/L. For the first arrangement, three stage processing resulted in an overall ~90% w/w cadmium removal, and the second configuration removed ~94% of the original cadmium ions. The operating mode of this device requires a periodic interruption of the feed flow, leading to down time. Thus there is a compelling motivation to the development of the continuous device. The continuous, hybrid magnetic field gradient separation device, designed in our lab, incorporates a 1.0 cm internal diameter 1m long, axially-rotating horizontal glass tube, with four axially located repeating magnetic units. Each magnetic unit consists of an alternating current solenoid surrounding the chamber followed by electromagnets at a distance of 4.0 cm from the end of the solenoid. A computer controlled DC current flowing in the electromagnet is used to generate radial magnetic field gradients within the tube, allowing magnetic particles to be drawn to the walls. MagaCell-Q magnetic particles were used to demonstrate the removal of cadmium ions from an aqueous solution. Three stage processing resulted in an overall ~92% cadmium removal. Thus, this breakthrough technology in continuous separation can lead to a large increase in processing volume and reduced down time compared to the flow-through device, without loss of removal efficiency. While the specific system studied here consists of removal of cadmium ions from an aqueous solution, the general principle of magnetic colloidal separation using the flow-through and continuous devices can be exploited for other environmental and biotechnological applications where large volumes of sample must be processed with high efficiency.

Ghebremeskel, Alazar Negusse

74

Magnetic and fluorescence-encoded polystyrene microparticles for cell separation  

NASA Astrophysics Data System (ADS)

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

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

2008-12-01

75

Study on magnetic separation for decontamination of cesium contaminated soil by using superconducting magnet  

NASA Astrophysics Data System (ADS)

The accident of Fukushima Daiichi nuclear power plant caused the diffusion of radioactive cesium over the wide area. We examined the possibility of applying magnetic separation method using the superconducting magnet, which can process a large amount of the soil in high speed, to the soil decontamination and volume reduction of the radioactive cesium contaminated soil. Clay minerals are classified as 2:1 and 1:1 types by the difference of their layer structures, and these types of minerals are respectively paramagnetic and diamagnetic including some exception. It is known that most of the radioactive cesium is strongly adsorbed on the clay, especially on 2:1 type clay minerals. It is expected that the method which can separate only 2:1 type clay minerals selectively from the mixture clay minerals can enormously contribute to the volume reduction of the contaminated soil. In this study, the components in the clay before and after separation were evaluated to estimate the magnetic separation efficiency by using X-ray diffraction. From the results, the decontamination efficiency and the volume reduction ratio were estimated in order to examine the appropriate separation conditions for the practical decontamination of the soil.

Igarashi, Susumu; Nomura, Naoki; Mishima, Fumihito; Akiyama, Yoko

2014-09-01

76

Magnetic Separation and Magnetic Properties of Low-Grade Manganese Carbonate Ore  

NASA Astrophysics Data System (ADS)

The relation between the magnetic separation behavior and magnetic properties of a low-grade manganese ore was analyzed before and after treatment by direct reduction with coal. It was found that raw ore with an initial average grade of 10.39% Mn and consisting of diamagnetic and paramagnetic minerals can be concentrated by high-intensity magnetic separation to produce a salable product with a grade of 22.75% Mn and a recovery of 89.88%. In contrast, direct reduction of the ore results in a new Mn-Fe oxide phase formed with a combination of ferromagnetic and paramagnetic properties, thereby increasing the magnetic susceptibilities of the ore by almost two orders of magnitude. The grade of Mn for the roasted ore could only be concentrated to 15.49% with a recovery of 66.67%. Therefore, it is concluded that the low-grade manganese ores with antiferromagnetic and paramagnetic (or diamagnetic, but not strongly ferromagnetic) properties could be efficiently beneficiated via high-intensity magnetic separation.

Wu, Y.; Shi, B.; Ge, W.; Yan, C. J.; Yang, X.

2014-11-01

77

The Development of the Separation Apparatus of Phosphor by Controlling the Magnetic Force  

NASA Astrophysics Data System (ADS)

The phosphor wastes contain the multiple kinds of rare-earth phosphors with high market value. Because of increasing demand for rare-earth, the technique to recover and reuse the rare-earth in the phosphor wastes is required. In this study, we focused on the difference of physical property such as magnetic susceptibility and density for each type of phosphor and tried to separate and recover the phosphors by using the magnetic separation technique utilizing the difference of the traction force to the magnet acting on the particles. Magneto-Archimedes method is method separation technique utilizi g the difference of magnetic susceptibility and density. We developed the magnetic separation apparatus by applying this technique. To develop the practical separation apparatus, the continuous process is required. Hence the fundamental experiment utilizing High Temperature Superconducting (HTS) Bulk Magnet which can generate the strong magnetic force was conducted. As a result, we succeeded the continuous separation of the phosphor wastes.

Wada, K.; Mishima, F.; Akiyama, Y.; Nishijima, S.

78

IMPROVEMENT OF IMMUNOMAGNETIC SEPARATION FOR ESCHERICHIA COLI O157:H7 DETECTION BY THE PICKPEN MAGNETIC PARTICLE SEPARATION DEVICE  

Technology Transfer Automated Retrieval System (TEKTRAN)

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 due to high background microflora that is not effectively washed awa...

79

Separation of Charged Particles from Magnetic Field Lines in Two-Component Magnetic Turbulence  

NASA Astrophysics Data System (ADS)

In interplanetary space, the transport of energetic charged particles is influenced by a turbulent magnetic field. Previous studies have shown that a two-component (2D+slab) magnetic model of turbulence is a useful model for the magnetic field in the heliosphere. Normally, the diffusive behavior of charged particles in a turbulent magnetic field is observed when they approach the long time limit. The charged particles are often assumed to follow and diffuse according to the random walk of the field lines but some theories of perpendicular particle transport, such as nonlinear guiding center theory (NLGC), implicitly assume some true cross-field diffusion in which particles separate from the field line connected to their initial location. Furthermore, such cross-field diffusion is of specific interest because it is the only way that particles can diffuse across boundaries of magnetic field topology, such as the heliospheric current sheet and boundaries of interplanetary magnetic flux ropes. In this work, we study such cross-field diffusion using numerical techniques to simulate the trajectories of charged particles and magnetic field lines in two-component magnetic turbulence and to find the separation between the particles and their initial magnetic field lines. The guiding centers (GC) of the particles are computed here. Then we calculate the spreading between the GC of the particles and the trajectories of the field lines. We found that, in the pure slab turbulence, the particles stick with the magnetic field lines at which they initially start. In the 2D+slab case, the particles initially follow their initial field lines and then spread diffusively in the long time limit. We perform simulations for varying particle energy, ratio of 2D to slab fluctuations, and strength of the magnetic fluctuation in order to understand the relationship between the particle and magnetic field line trajectories. The diffusion coefficients of the particles have been calculated and compared with previous theories. This will lead to better understanding about the mechanisms of particle transport and will also help in developing a more complete transport theory of energetic charged particles in magnetic turbulence. Partially supported by the Thailand Research Fund, NSF SHINE ATM-0752135, and NASA Heliophysics Theory Program NNX08AI47G.

Chuychai, P.; Ruffolo, D. J.; Matthaeus, W. H.

2010-12-01

80

Large Scale Magnetic Separation of Solanum tuberosum Tuber Lectin from Potato Starch Waste Water  

NASA Astrophysics Data System (ADS)

A simple procedure for large scale isolation of Solanum tuberosum tuber lectin from potato starch industry waste water has been developed. The procedure employed magnetic chitosan microparticles as an affinity adsorbent. Magnetic separation was performed in a flow-through magnetic separation system. The adsorbed lectin was eluted with glycine/HCl buffer, pH 2.2. The specific activity of separated lectin increased approximately 27 times during the isolation process.

Safarik, Ivo; Horska, Katerina; Martinez, Lluis M.; Safarikova, Mirka

2010-12-01

81

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

EPA Science Inventory

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

82

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

83

Application of high temperature superconductors to high-gradient magnetic separation  

SciTech Connect

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

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

1994-06-01

84

Application of high temperature superconductors to high-gradient magnetic separation  

NASA Astrophysics Data System (ADS)

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

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

85

Cryo-electron microscopy of viruses  

Microsoft Academic Search

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

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

1984-01-01

86

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

87

Journal of Magnetism and Magnetic Materials 293 (2005) 597604 Magnetic separation in microfluidic systems using  

E-print Network

or nanolitres), they are highly portable, and they are potentially inexpensive and thus disposable [6,7]. We-encapsulated in a dielectric layer and a nickel soft magnetic yoke on top of that. ARTICLE IN PRESS www

88

Magnetic separation in microfluidic systems using microfabricated electromagnets—experiments and simulations  

Microsoft Academic Search

We present experiments and simulations of magnetic separation of magnetic beads in a microfluidic channel. The separation is obtained by microfabricated electromagnets. The results of our simulations using FEMLAB and Mathematica are compared with experimental results obtained using our own microfabricated systems.

Kristian Smistrup; Ole Hansen; Henrik Bruus; Mikkel F. Hansen

2005-01-01

89

Application of coal petrography to the evaluation of magnetically separated dry crushed coals  

SciTech Connect

In the present study the open gradient magnetic separation method has been used to beneficiate the -30 + 100 mesh fraction of two high volatile bituminous coals. The evaluation of the effectiveness of the magnetic separation for cleaning these coals is the subject of this paper. Coal petrography in combination with scanning electron microscopy and x-ray diffractometry were used to characterize the magnetically separated coal fractions. These analyses revealed that the majority of the pyrite and non-pyrite minerals were concentrated in the positive magnetic susceptibility fractions. The bulk of the starting samples (approx. 80 weight percent) were located in the negative magnetic susceptibility fractions and showed significant reductions in pyrite and non-pyritic minerals. The magnetic separation appears to effectively split the samples into relatively clean coal and refuse.

Harris, L.A.; Hise, E.C.

1981-01-01

90

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

91

Loss separation in soft magnetic composites5 O. de la Barrire1  

E-print Network

1 1 2 3 4 Loss separation in soft magnetic composites5 6 7 8 9 O. de la Barrière1 , C. Appino2 , F and their frequency dependence26 in soft magnetic composites. Two types of bonded Fe-based materials have been/or high working frequencies [3] [4]. Soft46 magnetic composites (SMCs) are therefore often proposed

Paris-Sud XI, Université de

92

Cryo-electron tomography of bacterial viruses  

SciTech Connect

Bacteriophage particles contain both simple and complex macromolecular assemblages and machines that enable them to regulate the infection process under diverse environmental conditions with a broad range of bacterial hosts. Recent developments in cryo-electron tomography (cryo-ET) make it possible to observe the interactions of bacteriophages with their host cells under native-state conditions at unprecedented resolution and in three-dimensions. This review describes the application of cryo-ET to studies of bacteriophage attachment, genome ejection, assembly and egress. Current topics of investigation and future directions in the field are also discussed.

Guerrero-Ferreira, Ricardo C. [Division of Pediatric Infectious Diseases, Emory University School of Medicine, Children's Healthcare of Atlanta, Atlanta, GA 30322 (United States)] [Division of Pediatric Infectious Diseases, Emory University School of Medicine, Children's Healthcare of Atlanta, Atlanta, GA 30322 (United States); Wright, Elizabeth R., E-mail: erwrigh@emory.edu [Division of Pediatric Infectious Diseases, Emory University School of Medicine, Children's Healthcare of Atlanta, Atlanta, GA 30322 (United States)

2013-01-05

93

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

94

Chiral magnetic microspheres purified by centrifugal field flow fractionation and microspheres magnetic chiral chromatography for benzoin racemate separation.  

PubMed

Separation of enantiomers still remains a challenge due to their identical physical and chemical properties in a chiral environment, and the research on specific chiral selector along with separation techniques continues to be conducted to resolve individual enantiomers. In our laboratory the promising magnetic chiral microspheres Fe3O4@SiO2@cellulose-2, 3-bis (3,5-dimethylphenylcarbamate) have been developed to facilitate the resolution using both its magnetic property and chiral recognition ability. In our present studies this magnetic chiral selector was first purified by centrifuge field flow fractionation, and then used to separate benzoin racemate by a chromatographic method. Uniform-sized and masking-impurity-removed magnetic chiral selector was first obtained by field flow fractionation with ethanol through a spiral column mounted on the type-J planetary centrifuge, and using the purified magnetic chiral selector, the final chromatographic separation of benzoin racemate was successfully performed by eluting with ethanol through a coiled tube (wound around the cylindrical magnet to retain the magnetic chiral selector as a stationary phase) submerged in dry ice. In addition, an external magnetic field facilitates the recycling of the magnetic chiral selector. PMID:23891368

Tian, Ailin; Qi, Jing; Liu, Yating; Wang, Fengkang; Ito, Yoichiro; Wei, Yun

2013-08-30

95

Magnetic properties and loss separation in iron-silicone-MnZn ferrite soft magnetic composites  

NASA Astrophysics Data System (ADS)

This paper investigates the magnetic and structural properties of iron-based soft magnetic composites coated with silicone-MnZn ferrite hybrid. The organic silicone resin was added to improve the flexibility of the insulated iron powder and causes better adhesion between particles to increase the mechanical properties. Scanning electron microscopy and distribution maps show that the iron particle surface is covered with a thin layer of silicone-MnZn ferrite. Silicone-MnZn ferrite coated samples have higher permeability when compared with the non-magnetic silicone resin coated compacts. The real part of permeability increases by 34.18% when compared with the silicone resin coated samples at 20 kHz. In this work, a formula for calculating the total loss component by loss separation method is presented and finally the different parts of total losses are calculated. The results show that the eddy current loss coefficient is close to each other for the silicone-MnZn ferrite, silicone resin and MnZn ferrite coated samples (0.0078

Wu, Shen; Sun, Aizhi; Xu, Wenhuan; Zou, Chao; Yang, Jun; Dong, Juan

2013-12-01

96

Magnetic properties and loss separation in iron-silicone-MnZn ferrite soft magnetic composites  

SciTech Connect

This paper investigates the magnetic and structural properties of iron-based soft magnetic composites coated with silicone-MnZn ferrite hybrid. The organic silicone resin was added to improve the flexibility of the insulated iron powder and causes better adhesion between particles to increase the mechanical properties. Scanning electron microscopy and distribution maps show that the iron particle surface is covered with a thin layer of silicone-MnZn ferrite. Silicone-MnZn ferrite coated samples have higher permeability when compared with the non-magnetic silicone resin coated compacts. The real part of permeability increases by 34.18% when compared with the silicone resin coated samples at 20 kHz. In this work, a formula for calculating the total loss component by loss separation method is presented and finally the different parts of total losses are calculated. The results show that the eddy current loss coefficient is close to each other for the silicone-MnZn ferrite, silicone resin and MnZn ferrite coated samples (0.0078

Wu, Shen; Sun, Aizhi; Xu, Wenhuan; Zou, Chao; Yang, Jun; Dong, Juan [School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing (China)

2013-12-16

97

Haloing in bimodal magnetic colloids: the role of field induced phase separation , P.Kuzhir1  

E-print Network

be useful for the development of the bimodal magnetorheological fluids and of the magnetic separation to a stable fluid and back to colloidal gel with increasing nanoparticle concentration [1]. The stabilization

Boyer, Edmond

98

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...

99

High gradient magnetic separation of iron oxide minerals from soil clays  

E-print Network

HIGH GRADIENT MAGNETIC SEPARATION OF IRON OXIDE MINERALS FROM SOIL CLAYS A Thesis by DARRELL GENE SCHULZE Submitted to the Graduate College of Texas AIM University in partial fulfillment of the requirement for the degree of MASTER OF SCIENCE... December 1977 Major Subject: Soil Science HIGH GRADIENT MAGNETIC SEPARATION OF IRON OXIDE MINERALS FROM SOIL CLAYS A Thesis DARRELL GENE SCHULZE Approved as to style and content by: (Chairman of C ittee) epartm t) j (Member) (Membe December 1977...

Schulze, Darrell Gene

2012-06-07

100

Optimum shell separation for closed axial cylindrical magnetic shields  

NASA Astrophysics Data System (ADS)

The effect of shell separation on the axial shielding with closed double-shell cylindrical shields is investigated numerically. It is found that the optimum shell separation for practical, equal-thickness shields of the above type is considerably smaller than that for transverse spherical and infinitely long cylindrical shields: in most cases, air gaps equal 5%-10% of the inner shell diameter are wide enough to bring the shielding to 90% of its maximum. This indicates that closely spaced axial shields can be used without much sacrifice in performance. Taking into account the computed optimum shell separation for double-shell shields, one can easily optimize and design a compact and effective multishell shield. Based on the numerical study, an analytical approximation is suggested for the axial shielding with narrowly spaced double-shell cylindrical shields.

Paperno, Eugene; Peliwal, Saee; Romalis, Michael V.; Plotkin, Anton

2005-05-01

101

Quadrics on complex Riemannian spaces of constant curvature, separation of variables, and the Gaudin magnet  

Microsoft Academic Search

Integrable systems that are connected with orthogonal separation of variables in complex Riemannian spaces of constant curvature are considered herein. An isomorphism with the hyperbolic Gaudin magnet, previously pointed out by one of the authors, extends to coordinates of this type. The complete classification of these separable coordinate systems is provided by means of the corresponding L matrices for the

E. G. Kalnins; V. B. Kuznetsov; Willard Miller; Jr

1994-01-01

102

Use of High-Gradient Magnetic Fields for the Separation of Macromolecules  

Microsoft Academic Search

High gradient magnetic field separation (HGMS) has been used to separate several types of > 1 ?m sized ferro- or paramagnetic particles from bulk streams. The majority of the studies have been carried out using a single ferromagnetic wire or wire mesh to produce the field gradients necessary for particle capture. The purpose of this paper is to examine the

T. C. Scott; T. L. Brumfield

1988-01-01

103

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

Microsoft Academic Search

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

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

2002-01-01

104

A bio-magnetic bead separator on glass chips using semi-encapsulated spiral electromagnets  

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 are separately fabricated and then bonded. The device was tested with super-paramagnetic beads of mean diameter 0.83 ?m which were suspended in a buffered solution with solid concentration 10%. When a

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

1997-01-01

105

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

106

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. PMID:20368988

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

2010-01-01

107

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

108

Enhancement of magnetic separability in coal liquefaction residual solids  

Microsoft Academic Search

The conversion of coal to a clean fuel through liquefaction requires the physical separation of undissolved sulfur-rich mineral matter. The hydrogenation-liquefaction reaction produces residual solids in which the original coal impurity pyrite, FeS2, has largely been converted to pyrrhotite, Fe(1-x)S, which is a complex nonstoichiometric sulfide. By using thermomagnetic analysis and Moessbauer spectroscopy it is shown that the iron sulfide

I. S. Jacobs; L. M. Levinson

1979-01-01

109

Enhancement of magnetic separability in coal liquefaction residual solids  

Microsoft Academic Search

The conversion of coal to a clean fuel through liquefaction requires the physical separation of undissolved sulfur-rich mineral matter. The hydrogenation-liquefaction reaction produces residual solids in which the original coal impurity pyrite, FeS2, has largely been converted to pyrrhotite, Fe1?xS, which is a complex non-stoichiometric sulfide. Using thermomagnetic analysis and Mo¨ssbauer spectroscopy we show that the iron sulfide in coal

I. S. Jacobs; Lionel M. Levinson

1979-01-01

110

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.

111

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

SciTech Connect

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

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

1998-12-01

112

Measuring Thermal Conductivity and Moisture Absorption of Cryo-Insulation Materials  

NASA Technical Reports Server (NTRS)

NASA is seeking to develop thermal insulation material systems suitable for withstanding both extremely high temperatures encountered during atmospheric re-entry heating and aero- braking maneuvers, as well as extremely low temperatures existing in liquid fuel storage tanks. Currently, materials used for the high temperature insulation or Thermal Protection System (TPS) are different from the low temperature, or cryogenic insulation. Dual purpose materials are necessary to the development of reusable launch vehicles (RLV). The present Space Shuttle (or Space Transportation System, STS) employs TPS materials on the orbiter and cryo-insulation materials on the large fuel tank slung under the orbiter. The expensive fuel tank is jettisoned just before orbit is achieved and it burns up while re-entering over the Indian Ocean. A truly completely reusable launch vehicle must store aR cryogenic fuel internally. The fuel tanks will be located close to the outer surface. In fact the outer skin of the craft will probably also serve as the fuel tank enclosure, as in jet airliners. During a normal launch the combined TPS/cryo-insulation system will serve only as a low temperature insulator, since aerodynamic heating is relatively minimal during ascent to orbit. During re-entry, the combined TPS/cryo-insulation system will serve only as a high temperature insulator, since all the cryogenic fuel will have been expended in orbit. However, in the event of an.aborted launch or a forced/emergency early re-entry, the tanks will still contain fuel, and the TPS/cryo-insulation will have to serve as both low and high temperature insulation. Also, on long duration missions, such as to Mars, very effective cryo-insulation materials are needed to reduce bod off of liquid propellants, thereby reducing necessary tankage volume, weight, and cost. The conventional approach to obtaining both low and high temperature insulation, such as is employed for the X-33 and X-34 spacecraft, is to use separate TPS and cryo-insulation materials, which are connected by means of adhesives or stand-offs (spacers). Three concepts are being considered: (1) the TPS is bonded directly to the cryo-insulation which, in turn, is bonded to the exterior of the tank, (2) stand-offs are used to make a gap between the TPS and the cryo-insulation, which is bonded externally to the tank, (3) TPS is applied directly or with stand-offs to the exterior so the tank, and cryo-insulation is applied directly to the interior of the tank. Many potential problems are inherent in these approaches. For example, mismatch between coefficients of thermal expansion of the TPS and cryo-insulation, as well as aerodynamic loads, could lead to failure of the bond. Internal cryo-insulation must be prevent from entering the sump of the fuel turbo-pump. The mechanical integrity of the stand-off structure (if used) must withstand multiple missions. During ground hold (i.e., prior to launch) moisture condensation must be minimized in the gap between the cryo-insulation and the TPS. The longer term solution requires the development of a single material to act as cryo- insulation during ground hold and as TPS during re-entry. Such a material minimizes complexity and weight while improving reliability and reducing cost.

Lambert, Michael A.

1998-01-01

113

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

NASA Astrophysics Data System (ADS)

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

Rusin, Tomasz M.; Zawadzki, Wlodek

2012-08-01

114

Hour-glass magnetic excitations induced by nanoscopic phase separation in cobalt oxides.  

PubMed

The magnetic excitations in the cuprate superconductors might be essential for an understanding of high-temperature superconductivity. In these cuprate superconductors the magnetic excitation spectrum resembles an hour-glass and certain resonant magnetic excitations within are believed to be connected to the pairing mechanism, which is corroborated by the observation of a universal linear scaling of superconducting gap and magnetic resonance energy. So far, charge stripes are widely believed to be involved in the physics of hour-glass spectra. Here we study an isostructural cobaltate that also exhibits an hour-glass magnetic spectrum. Instead of the expected charge stripe order we observe nano phase separation and unravel a microscopically split origin of hour-glass spectra on the nano scale pointing to a connection between the magnetic resonance peak and the spin gap originating in islands of the antiferromagnetic parent insulator. Our findings open new ways to theories of magnetic excitations and superconductivity in cuprate superconductors. PMID:25534540

Drees, Y; Li, Z W; Ricci, A; Rotter, M; Schmidt, W; Lamago, D; Sobolev, O; Rütt, U; Gutowski, O; Sprung, M; Piovano, A; Castellan, J P; Komarek, A C

2014-01-01

115

Hour-glass magnetic excitations induced by nanoscopic phase separation in cobalt oxides  

NASA Astrophysics Data System (ADS)

The magnetic excitations in the cuprate superconductors might be essential for an understanding of high-temperature superconductivity. In these cuprate superconductors the magnetic excitation spectrum resembles an hour-glass and certain resonant magnetic excitations within are believed to be connected to the pairing mechanism, which is corroborated by the observation of a universal linear scaling of superconducting gap and magnetic resonance energy. So far, charge stripes are widely believed to be involved in the physics of hour-glass spectra. Here we study an isostructural cobaltate that also exhibits an hour-glass magnetic spectrum. Instead of the expected charge stripe order we observe nano phase separation and unravel a microscopically split origin of hour-glass spectra on the nano scale pointing to a connection between the magnetic resonance peak and the spin gap originating in islands of the antiferromagnetic parent insulator. Our findings open new ways to theories of magnetic excitations and superconductivity in cuprate superconductors.

Drees, Y.; Li, Z. W.; Ricci, A.; Rotter, M.; Schmidt, W.; Lamago, D.; Sobolev, O.; Rütt, U.; Gutowski, O.; Sprung, M.; Piovano, A.; Castellan, J. P.; Komarek, A. C.

2014-12-01

116

Removal of freshwater microalgae by a magnetic separation method  

NASA Astrophysics Data System (ADS)

Some species of microalgae, with high growth rate and high lipid content, appear to be attractive alternatives as a feedstock for biodiesel production. The high-energy input for harvesting biomass and removing the water from the algae makes current commercial microalgal biodiesel production cost expensive. The major techniques currently employed in microalgae harvesting and recovery include centrifugation, coagulation-flocculation, bio-flocculation, filtration and screening, gravity sedimentation, and flotation. The purpose of this study was to investigate the harvesting of microalgae cells by coagulation using magnetic activated carbon, magnetite (FeO4) nanoparticles, and common chemical coagulants. Scenedesmus rubescens was selected and cultivated in 10 L flasks under continuous artificial light. Samples were taken at different operation intervals. Jar tests were conducted to investigate the effect of adsorption of microalgae on the magnetic material. The removal efficiency of microalgae was affected by the coagulants dose, stirring time and speed, and the initial microalgae concentration. The recovery of microalgae was greater in cultures with high initial microalgae concentration compared to cultures with low microalgae concentrations.

Vergini, Sofia S.; Aravantinou, Andriana F.; Manariotis, Ioannis D.

2013-04-01

117

High Temperature Superconducting Reciprocating Magnetic Separator Final Report  

SciTech Connect

In 2001, under DOE's Superconductivity Partnership Initiative (SPI), E. I. du Pont de Nemours & Co. (Dupont) was awarded a cost-share contract to build a fully functional full-scale model high temperature superconducting reciprocating magnet unit specifically designed for the koalin clay industry. After competitive bidding, American Superconductor (AMSC) was selected to provide the coil for the magnet. Dupont performed the statement of work until September 2004, when it stopped work, with the concurrence of DOE, due to lack of federal funds. DOE had paid all invoices to that point, and Dupont had provided all cost share. At this same time, Dupont determined that this program did not fit with its corporate strategies and notified DOE that it was not interesting in resuming the program when funding became available. AMSC expressed interest in assuming performance of the Agreement to Dupont and DOE, and in March 2005, this project was transferred to AMSC by DOE amendment to the original contract and Novation Agreement between AMSC and Dupont. Design drawings and some hardware components and subassemblies were transferred to AMSC. However, no funding was obligated by DOE and AMSC never performed work on the project. This report contains a summary of the work performed by Dupont up to the September 04 timeframe.

James F. Maguire

2008-06-05

118

High gradient magnetic separation versus expanded bed adsorption: a first principle comparison.  

PubMed

A robust new adsorptive separation technique specifically designed for direct product capture from crude bioprocess feedstreams is introduced and compared with the current bench mark technique, expanded bed adsorption. The method employs product adsorption onto sub-micron sized non-porous superparamagnetic supports followed by rapid separation of the 'loaded' adsorbents from the feedstock using high gradient magnetic separation technology. For the recovery of Savinase from a cell-free Bacillus clausii fermentation liquor using bacitracin-linked adsorbents, the integrated magnetic separation system exhibited substantially enhanced productivity over expanded bed adsorption when operated at processing velocities greater than 48 m h(-1). Use of the bacitracin-linked magnetic supports for a single cycle of batch adsorption and subsequent capture by high gradient magnetic separation at a processing rate of 12 m h(-1) resulted in a 2.2-fold higher productivity relative to expanded bed adsorption, while an increase in adsorbent collection rate to 72 m h(-1) raised the productivity to 10.7 times that of expanded bed adsorption. When the number of batch adsorption cycles was then increased to three, significant drops in both magnetic adsorbent consumption (3.6 fold) and filter volume required (1.3 fold) could be achieved at the expense of a reduction in productivity from 10.7 to 4.4 times that of expanded bed adsorption. PMID:11787803

Hubbuch, J J; Matthiesen, D B; Hobley, T J; Thomas, O R

2001-01-01

119

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

120

Laser isotope separation of barium using an inhomogeneous magnetic field  

NASA Astrophysics Data System (ADS)

A barium atomic beam undergoes selective isotopic excitation by a dye laser to the 1P1 state. This state radiatively decays back to the ground state or to the (6s5d)D states, which are deflected out of the beam by an inhomogeneous magnetic field. The residual atomic beam is examined by a quadrupole mass spectrometer, and isotopic depletions of up to 60% are obtained using laser powers of a few hundred milliwatts. The isotopic splitting of the 1S0-->1P1 transitions for 136Ba and the F=5/2 states of 135,137Ba are measured relative to that for 138Ba and agree well with those found previously.

van Wijngaarden, W. A.; Li, J.

1994-02-01

121

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

122

Quadrics on Complex Riemannian Spaces of Constant Curvature, Separation of Variables and the Gaudin Magnet  

E-print Network

We consider integrable systems that are connected with orthogonal separation of variables in complex Riemannian spaces of constant curvature. An isomorphism with the hyperbolic Gaudin magnet, previously pointed out by one of us, extends to coordinates of this type. The complete classification of these separable coordinate systems is provided by means of the corresponding $L$-matrices for the Gaudin magnet. The limiting procedures (or $\\epsilon $ calculus) which relate various degenerate orthogonal coordinate systems play a crucial result in the classification of all such systems.

E. G. Kalnins; V. B. Kuznetsov; Willard Miller, Jr

1993-08-23

123

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

124

Magnetic separation and evaluation of magnetization of Brazilian soils from different parent materials  

Microsoft Academic Search

Ten selected Brazilian soils representative of Oxisols, Ultisols, Alfisols and Inceptisols and derived from gneiss, basalt, sandstone, diabase and itabirite were sampled and examined to provide insight into the behavior of their magnetic minerals. The objective was to measure the magnetization of the sand, silt and clay fractions and to submit the clay fraction to variable magnetic fields to obtain

M. P. F. Fontes; T. S. de Oliveira; L. M. da Costa; A. A. G. Campos

2000-01-01

125

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

Microsoft Academic Search

We investigate a non-locality of Moss–Okninski transformation (MOT) used to separate positive and negative energy states in the 3+1 Dirac equation for relativistic electrons in the presence of a magnetic field. Properties of functional kernels generated by the MOT are analyzed and kernel non-localities are characterized by calculating their second moments parallel and perpendicular to the magnetic field. Transformed functions

Tomasz M Rusin; Wlodek Zawadzki

2012-01-01

126

Cryo-compressed Hydrogen Storage. Tobias Brunner  

E-print Network

Cryo-compressed Hydrogen Storage. Tobias Brunner February 15th, 2011, Washington D.C. BMW Hydrogen. Hydrogen Storage Workshop. BMW EfficientDynamics Less emissions. More driving pleasure. #12;BMW Hydrogen Washington DC 02/15/2011 Page 2 BMW Hydrogen Technology Strategy. Advancement of key components. Source: BMW

127

Conceptual design of integrated microfluidic system for magnetic cell separation, electroporation, and transfection.  

PubMed

For the purposes of a successful ex vivo gene therapy we have proposed and analyzed a new concept of an integrated microfluidic system for combined magnetic cell separation, electroporation, and magnetofection. For the analysis of magnetic and electric field distribution (given by Maxwell equations) as well as dynamics of magnetically labeled cell and transfection complex, we have used finite element method directly interfaced to the Matlab routine solving Newton dynamical equations of motion. Microfluidic chamber has been modeled as a channel with height and length 1 mm and 1 cm, respectively. Bottom electrode consisted of 100 parallel ferromagnetic straps and the upper electrode was plate of diamagnetic copper. From the dynamics of magnetic particle motion we have found that the characteristic time-scales for the motion of cells (mean capture time ? 4 s) and gene complexes (mean capture time ? 3 min), when permanent magnets are used, are in the range suitable for efficient cell separation and gene delivery. The largest electric field intensity (?10 kV/m) was observed at the edges of the microelectrodes, in the close proximity of magnetically separated cells, which is optimal for subsequent cell electroporation. PMID:23260767

Durdík, Š; Kraf?ík, A; Babincová, M; Babinec, P

2013-09-01

128

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. PMID:24238600

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

2014-01-01

129

Recovery of iron from cyanide tailings with reduction roasting-water leaching followed by magnetic separation.  

PubMed

Cyanide tailing is a kind of solid waste produced in the process of gold extraction from gold ore. In this paper, recovery of iron from cyanide tailings was studied with reduction roasting-water leaching process followed by magnetic separation. After analysis of chemical composition and crystalline phase, the effects of different parameters on recovery of iron were chiefly introduced. Systematic studies indicate that the high recovery rate and grade of magnetic concentrate of iron can be achieved under the following conditions: weight ratios of cyanide tailings/activated carbon/sodium carbonate/sodium sulfate, 100:10:3:10; temperature, 50 °C; time, 60 min at the reduction roasting stage; the liquid to solid ratio is 15:1 (ml/g), leaching at 60 °C for 5 min and stirring speed at 20 r/min at water-leaching; exciting current is 2A at magnetic separation. The iron grade of magnetic concentrate was 59.11% and the recovery ratio was 75.12%. The mineralography of cyanide tailings, roasted product, water-leached sample, magnetic concentrate and magnetic tailings were studied by X-ray powder diffraction (XRD) technique. The microstructures of above products except magnetic tailings were also analyzed by scanning electron microscope (SEM) and energy disperse spectroscopy (EDS) to help understand the mechanism. PMID:22333161

Zhang, Yali; Li, Huaimei; Yu, Xianjin

2012-04-30

130

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

SciTech Connect

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 [Rare Isotope Science Project, Institute for Basic Science, Yuseong, Daejeon, 305-811 (Korea, Republic of)

2014-01-29

131

Practical workflow for cryo focused-ion-beam milling of tissues and cells for cryo-TEM tomography  

PubMed Central

Vitreous freezing offers a way to study cells and tissue in a near-native state by cryo-transmission electron microscopy (cryo-TEM), which is important when structural information at the macromolecular level is required. Many cells -- especially those in tissue -- are too thick to study intact in the cryo-TEM. Cryo focused-ion-beam (cryo-FIB) milling is being used in a few laboratories to thin vitreously frozen specimens, thus avoiding the artifacts and difficulties of cryo-ultramicrotomy. However, the technique is challenging because of the need to avoid devitrification and frost accumulation during the entire process, from the initial step of freezing to the final step of loading the specimen into the cryo-TEM. We present a robust workflow that makes use of custom fixtures and devices that can be used for high-pressure-frozen bulk tissue samples as well as for samples frozen on TEM grids. PMID:24211822

Hsieh, Chyongere; Schmelzer, Thomas; Kishchenko, Gregory; Wagenknecht, Terence; Marko, Michael

2013-01-01

132

Magnetic characteristics of phase-separated CeO2:Co thin films  

NASA Astrophysics Data System (ADS)

Herewith, we are reporting the magnetic properties of phase-separated Co-doped CeO2 films (with a Ce:Co atomic-ratio of 0.97:0.03) grown on single-crystal SrTiO3 (001) substrates. A comparison of the magnetic characteristics of these films with those of homogenously doped CeO2:Co films of the same composition illustrates the significant differences in their magnetic behavior. These behavioral characteristics provide a model for determining if the magnetic behavior observed in this, as well as in other diluted magnetic dielectric systems, is due to homogeneous doping, a mixture of doping and transition metal cluster formation, or exists purely as a result of transition metal clustering.

Prestgard, M. C.; Siegel, G.; Ma, Q.; Tiwari, A.

2013-09-01

133

Single-step synthesis and magnetic separation of graphene and carbon nanotubes in arc discharge plasmas  

Microsoft Academic Search

The unique properties of graphene and carbon nanotubes made them the most promising nanomaterials attracting enormous attention, due to the prospects for applications in various nanodevices, from nanoelectronics to sensors and energy conversion devices. Here we report on a novel deterministic, single-step approach to simultaneous production and magnetic separation of graphene flakes and carbon nanotubes in an arc discharge by

O. Volotskova; I. Levchenko; A. Shashurin; Y. Raitses; K. Ostrikov; M. Keidar

2010-01-01

134

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

2014-07-18

135

Calibration of analyzing magnet for beam energy measurement using the recoil mass separator HIRA  

NASA Astrophysics Data System (ADS)

Beam energy measurements have been carried out using the energy achromatic recoil mass separator HIRA at NSC. The energy was obtained from a measurement of the time-of-flight through HIRA which offers a flight distance of about 8.8 m. The method is quite useful for the calibration of the analyzer magnet over the entire operating range.

Madhavan, N.; Das, J. J.; Sugathan, P.; Kataria, D. O.; Avasthi, D. K.; Mandal, A.; Sinha, A. K.

1996-02-01

136

Preparation and characterization of chemically functionalized silica-coated magnetic nanoparticles as a DNA separator.  

PubMed

The work describes a simple and convenient process for highly efficient and direct DNA separation with functionalized silica-coated magnetic nanoparticles. Iron oxide magnetic nanoparticles and silica-coated magnetic nanoparticles were prepared uniformly, and the silica coating thickness could be easily controlled in a range from 10 to 50 nm by changing the concentration of silica precursor (TEOS) including controlled magnetic strength and particle size. A change in the surface modification on the nanoparticles was introduced by aminosilanization to enhance the selective DNA separation resulting from electrostatic interaction. The efficiency of the DNA separation was explored via the function of the amino-group numbers, particle size, the amount of the nanoparticles used, and the concentration of NaCl salt. The DNA adsorption yields were high in terms of the amount of triamino-functionalized nanoparticles used, and the average particle size was 25 nm. The adsorption efficiency of aminofunctionalized nanoparticles was the 4-5 times (80-100%) higher compared to silica-coated nanoparticles only (10-20%). DNA desorption efficiency showed an optimum level of over 0.7 M of the NaCl concentration. To elucidate the agglomeration of nanoparticles after electrostatic DNA binding, the Guinier plots were calculated from small-angle X-ray diffractions in a comparison of the results of energy diffraction TEM and confocal laser scanning microscopy. Additionally, the direct separation of human genomic DNA was achieved from human saliva and whole blood with high efficiency. PMID:19099431

Kang, Kiho; Choi, Jinsub; Nam, Joong Hee; Lee, Sang Cheon; Kim, Kyung Ja; Lee, Sang-Won; Chang, Jeong Ho

2009-01-15

137

Low-Field Magnetic Separation of Monodisperse Fe3O4 Nanocrystals  

E-print Network

William W. Yu,1 Arjun Prakash,2 Joshua C. Falkner,1 Sujin Yean,3 Lili Cong,3 Heather J. Shipley,3 Amy Kan-of-use water purification and the simultaneous separation of complex mixtures. High­surface area with arsenic removal from water by orders of magnitude. Additionally, the size dependence of magnetic

138

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

139

Residual Separation of Magnetic Fields Using a Cellular Neural Network Approach  

Microsoft Academic Search

- In this paper, a Cellular Neural Network (CNN) has been applied to a magnetic regional\\/residual anomaly separation problem. CNN is an analog parallel computing paradigm defined in space and characterized by the locality of connections between processing neurons. The behavior of the CNN is defined by the template matrices A, B and the template vector I. We have optimized

A. M. Albora; A. Özmen; O. N. Uçan

2001-01-01

140

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...

141

Magnetic separation of Dy(III) ions from homogeneous aqueous solutions  

NASA Astrophysics Data System (ADS)

The possibility to enrich paramagnetic dysprosium(III) ions in a magnetic field gradient is proved by means of interferometry, which may open the route for a magnetic separation of rare earth ions from aqueous solutions. The separation dynamics are studied for three different concentrations of DyCl3 and compared with those found recently in a sulphate solution of the 3d ion Mn(II). In view of the similar-sized hydration spheres for Dy(III) and Mn(II), the slower separation dynamics in DyCl3 is attributed to both a higher densification coefficient and the strong impact of Brownian motion due to the absence of ion-pair clusters.

Pulko, B.; Yang, X.; Lei, Z.; Odenbach, S.; Eckert, K.

2014-12-01

142

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

143

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

144

SEPARATION OF VARIABLES AND THE XXZ GAUDIN MAGNET E.G. KALNINS, V.B. KUZNETSOV and WILLARD MILLER, Jr.  

E-print Network

SEPARATION OF VARIABLES AND THE XXZ GAUDIN MAGNET E.G. KALNINS, V.B. KUZNETSOV and WILLARD MILLER, Minnesota 55455, USA. Abstract. In this work we generalise previous results connecting (rational) Gaudin the relationship between the separable systems and the Gaudin magnet [4,9] integrable systems models has been

145

SEPARATION OF VARIABLES AND THE XXZ GAUDIN MAGNET E.G. KALNINS, V.B. KUZNETSOV and WILLARD MILLER, Jr.  

E-print Network

SEPARATION OF VARIABLES AND THE XXZ GAUDIN MAGNET E.G. KALNINS, V.B. KUZNETSOV and WILLARD MILLER, Minnesota 55455, USA. Abstract. In this work we generalise previous results connecting (rational) Gaudin between the separable systems and the Gaudin magnet [4,9] integrable systems models has been established

146

Magnetic separation of proteins by a self-assembled supramolecular ternary complex.  

PubMed

The easy and effective separation of proteins from a mixture is crucial in proteomics. A supramolecular method is described to selectively capture and precipitate one protein from a protein mixture upon application of a magnetic field. A multivalent complex self-assembles in a dilute aqueous solution of three components: magnetic nanoparticles capped with cyclodextrin, non-covalent cross-linkers with an adamantane and a carbohydrate moiety, and lectins. The self-assembled ternary complex is precipitated in a magnetic field and readily redispersed with the aid of a non-ionic surfactant and competitive binding agents. This strategy to purify proteins by supramolecular magnetic precipitation is highly selective and efficient. PMID:25250697

Samanta, Avik; Ravoo, Bart Jan

2014-11-17

147

Separation Nanotechnology of Diethylenetriaminepentaacetic Acid Bonded Magnetic Nanoparticles for Spent Nuclear Fuel  

SciTech Connect

A nanomagnetic separation method based on Diethylenetriaminepentaacetic acid (DTPA) conjugated with magnetic nanoparticles (MNPs) is studied for application in spent nuclear fuel separation. The high affinity of DTPA towards actinides aids in separation from the highly acidic medium of nuclear waste. The solubility and magnetization of particles at low pH is protected by encapsulating them in silica layer. Surface functionalization of silica coated particles with polyamines enhances the loading capacity of the chelators on MNPs. The particles were characterized before and after surface modification using transmission electron microscopy (TEM), helium ion microscopy (HIM), Fourier transform-infrared (FT-IR) spectrometry, and X-ray diffractometry. The coated and uncoated samples were studied using vibrating sample magnetometer (VSM) to understand the change in magnetic properties due to the influence of the surface functionalization. The hydrodynamic size and surface charge of the particles are investigated using Dynamic Light Scattering (DLS). The uptake behavior of Am(III), Pu(IV), U(VI), and Np(V) from 0.1M NaNO3 solution was investigated. The sorption result shows the strong affinity of DTPA towards Am(III) and Pu(IV) by extracting 97% and 80% of actinides, respectively. The high removal efficiency and fast uptake of actinides make the chelator conjugated MNPs an effective method for spent nuclear fuel separation.

Kaur, Maninder [Idaho Univ., Moscow, ID (United States); Johnson, Andrew [Idaho Univ., Moscow, ID (United States); Tian, Guoxin [Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States); Jiang, Weilin [Pacific Northwest National Laboratory (PNNL), Richland, WA (United States); Rao, Linfeng [Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States); Paszczynski, Andrzej [Idaho Univ., Moscow, ID (United States); Qiang, You [Center for Advanced Energy Studies, Idaho Falls, ID (United States); Idaho Univ., Moscow, ID (United States)

2013-01-15

148

AMSD Reaction Structure Cryo Deformation Test Plan  

NASA Technical Reports Server (NTRS)

The method developed for measuring both in-plane & out-of-plane cryo deformations of AMSD reaction structures at the XRCF will be presented. For in-plane measurements, a theodolite is used to track the positions of several (up to ten) targets on the reaction structure. For out-of-plane measurements, the Leica ADM is used to measure the change in distance to several (up to ten) corner cubes attached to the reaction structure.

Eng, Ron; Hraba, John; Thornton, Gary; Baker, Mark; Haight, Harlan; Hadaway, James; Blackwell, Lisa; Stahl, Phil (Technical Monitor)

2002-01-01

149

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. PMID:18566823

Lu?i?, Vladan; Leis, Andrew

2008-01-01

150

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

151

On-chip micro-electromagnets for magnetic-based bio-molecules separation  

NASA Astrophysics Data System (ADS)

This paper reports a comprehensive theoretical, finite element and measurement analysis of different designs of planar micro-electromagnets for bio-molecular manipulation. The magnetic field due to current flowing in complex shapes of current-carrying conductors have been calculated analytically, simulated using finite-element analysis (FEA), and measured using the superconducting quantum interference device technique (SQUID). A comparison of the theoretical and measured magnetic field strength and patterns is presented. The planar electromagnets have been fabricated using patterned Al 2 ?m thick. The aim of the study is to explore and optimize the geometrical and structural parameters of planar electromagnets that give rise to the highest magnetic fields and forces for magnetic micro-beads manipulation. Magnetic beads are often used in biochemical assays for separation of bio-molecules. Typical beads are 0.2- 10 ?m in diameter and have superparamagnetic properties. Increasing the intensity of the magnetic field generated by a coil by injection a larger current is not the most suitable solution as the maximum current is limited by Joule heating. Consequently, in order to maximize the field for a given current, one should optimize the geometry of the coil, as this is an extremely significant factor in determining the magnetic field intensity in 2D planar designs. The theoretical and measured results of this work show that the meander micro-electromagnet with mesh-shaped winding profile produces the strongest magnetic field (about 2.7 ?T for a current intensity of 6 mA) compared with other meander designs, such as the serpentine and rosette-shaped ones. The magnetic fields of these three types of meander-shaped micro-electromagnets were compared theoretically with that produced by a spiral micro-electromagnet whose technological realization is more complicated and costly due to the fact that it requires an additional insulation layer with a contact window and a second patterned metal layer as a via. Nevertheless, the spiral design produces a much stronger magnetic field up to five times larger than that of the mesh-shaped micro-electromagnet for the same current and electromagnet area. The measured results strongly agree with these conclusions resulted from the theoretical analysis. The results presented in this paper provide a solid and useful basis for the design of a micro-fluidic bio-molecule separation and detection system using magnetic fields and magnetic beads.

Ramadan, Qasem; Samper, Victor; Poenar, Daniel; Yu, Chen

2004-10-01

152

Combined performance of biochar sorption and magnetic separation processes for treatment of chromium-contained electroplating wastewater.  

PubMed

Magnetic biochar was prepared with eucalyptus leaf residue remained after essential oil being extracted. Batch experiments were conducted to examine the capacity of the magnetic biochar to remove Cr (VI) from electroplating wastewater and to be separated by an external magnetic field. The results show that the initial solution pH plays an important role on both sorption and separation. The removal rates of Cr (VI), total Cr, Cu (II), and Ni (II) were 97.11%, 97.63%, 100% and 100%, respectively. The turbidity of the sorption-treated solution was reduced to 21.8NTU from 4075NTU after 10min magnetic separation. The study also confirms that the magnetic biochar still retains the original magnetic separation performance after the sorption process. PMID:25463783

Wang, Sheng-Ye; Tang, Yan-Kui; Li, Kun; Mo, Ya-Yuan; Li, Hao-Feng; Gu, Zhan-Qi

2014-10-01

153

Magnetic Field Separation Around Planets Using an Adjoint-Method Approach  

NASA Astrophysics Data System (ADS)

The two spacecraft of the BepiColombo mission will reach planet Mercury in 2022. The magnetometers on-board these polar orbiting spacecraft will provide a detailed map of the magnetic field in Mercury's environment. Unfortunately, a separation of the magnetic field into internal and external parts using the classical Gauss-algorithm is not possible due to strong electric currents in the orbit region of the spacecraft. These currents are due to the interaction of the solar wind with Mercury's planetary magnetic field. We use an MHD code to simulate this interaction process. This requires a first choice of Mercury's planetary field which is used and modified until the simulation results fit to the actual measurements. This optimization process is carried out most efficiently using an adjoint-method. The adjoint-method is well known for its low computational cost in order to determine sensitivities required for the minimization. In a first step, the validity of our approach to separate magnetic field contributions into internal and external parts is demonstrated using synthetic generated data. Furthermore, we apply our approach to satellite measurements of the Earth's magnetic field. We can compare the results with the well known planetary field of the Earth to prove practical suitability.

Nabert, Christian; Glassmeier, Karl-Heinz; Heyner, Daniel; Othmer, Carsten

154

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

NASA Astrophysics Data System (ADS)

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 88Sr+ 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.

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

2014-06-01

155

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

156

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

157

Preparation of thermosensitive polymer magnetic particles and their application in protein separations.  

PubMed

This paper presents a kind of thermoresponsive polymeric magnetic particles for protein separations. The magnetofluids were directly encapsulated in hollow particles constructed by self-assembly of rod-coil poly(ethylene glycol)-poly(N-isopropylacrylamide)/?-cyclodextrin (PEG-PNIPAM/?-CD) complexes. The resulting particles showed reversible protein absorption/desorption capacity because the reversible thermo-sensitivity of PNIPAM. Above the lower critical solution temperature (LCST) of PNIPAM, these particles showed high absorptive capacities and adsorption was done at lower temperature. The protein-laden particles are readily removed from the feed solution in a magnetic field. PMID:25222511

Luo, Ling; Zhang, Hong-Su; Liu, Yan; Ha, Wei; Li, Luo-Hao; Gong, Xiao-Lei; Li, Bang-Jing; Zhang, Sheng

2014-12-01

158

Magnetic Tilts and Polarity Separations in Sunspot Groups and Active Regions the Cycle 23  

NASA Astrophysics Data System (ADS)

We present the analysis of magnetic tilts in active regions and sunspot groups for 1996-2005 that are automatically extracted from the Solar Feature Catalogues (http://solar.inf.brad.ac.uk ). We investigate the statistical variations of magnetic field tilt in sunspot groups and whole active regions, their longitudinal and latitudinal distributions, drifts and daily polarity separation during different phases of the solar cycle 23. The classification results are compared with the similar research for the previous cycles and the specifics on the cycle 23 is discussed in conjunction to the solar dynamo theory.

Zharkov, S. I.; Zharkova, V. V.

2006-08-01

159

A simple magnetic separation method for high-yield isolation of pure primary microglia.  

PubMed

Microglial cells play a dynamic role in the brain beyond their established function of immune surveillance. Activated microglia play key roles in neural development, neuroinflammation, neural repair and neurotoxicity. They are particularly important in several neurodegenerative diseases in which sustained microglial activation contributes to the progression of neurodegenerative processes. Consequently, understanding microglial function in CNS health and disease has become an area of active research in recent years. However, a significant obstacle to progress in this field has been the inherent difficulties in obtaining large amounts of primary microglial cells to routinely perform mechanistic studies and characterize signaling pathways regulating the dynamics of microglial activation. Herein, we describe a novel column-free magnetic separation protocol for high-yield isolation of primary microglia from mouse postnatal mixed glial cultures. The procedure is based on optimized culture conditions that enable high microglial cell densities in confluent mixed glial cultures followed by highly efficient recovery of pure microglia by magnetic separation. The novel column-free magnetic separation system utilizes tetrameric antibody complexes (TAC) with dual specificity for CD11b-PE labeled microglia and dextran magnetic nanoparticles. An FcR blocker (anti-CD16/32) is added to enhance the purity of the microglial separation by preventing non-specific labeling of other cell types. This procedure yields on average >3×10? microglial cells per mouse pup, with a remarkable purity of 97% and recovery of around 87% of microglia from the mixed glial population. Importantly, the microglia obtained by this method are fully functional and respond like cells obtained by conventional isolation techniques. PMID:21074565

Gordon, Richard; Hogan, Colleen E; Neal, Matthew L; Anantharam, Vellareddy; Kanthasamy, Anumantha G; Kanthasamy, Arthi

2011-01-15

160

Spin-charge separation in two-dimensional frustrated quantum magnets.  

PubMed

The dynamics of a mobile hole in two-dimensional frustrated quantum magnets is investigated by exact diagonalization techniques. Our results provide evidence for spin-charge separation upon doping the kagome lattice, a prototype of a spin liquid. In contrast, in the checkerboard lattice, a symmetry broken valence bond crystal, a small quasiparticle peak is seen for some crystal momenta, a finding interpreted as a restoration of weak holon-spinon confinement. PMID:15245179

Läuchli, Andreas; Poilblanc, Didier

2004-06-11

161

Magnetic properties and loss separation in iron powder soft magnetic composite materials  

Microsoft Academic Search

New developments in powder metallurgical composites make soft magnetic composite (SMC) material interesting for application in electrical machines, when combined with new machine design rules and new production techniques. In order to establish these design rules, one must pay attention to electromagnetic loss characteristics of SMC material. In this work, five different series of iron based SMCs are produced and

Marc de Wulf; Ljubomir Anestiev; Luc Dupré; Ludo Froyen; Jan Melkebeek

2002-01-01

162

SERS-fluorescence joint spectral encoded magnetic nanoprobes for multiplex cancer cell separation.  

PubMed

A new kind of cancer cell separation method is demonstrated, using surface-enhanced Raman scattering (SERS) and fluorescence dual-encoded magnetic nanoprobes. The designed nanoprobes can realize SERS-fluorescence joint spectral encoding (SFJSE) and greatly improve the multiplexing ability. The nanoprobes have four main components, that is, the magnetic core, SERS generator, fluorescent agent, and targeting antibody. These components are assembled with a multi-layered structure to form the nanoprobes. Specifically, silica-coated magnetic nanobeads (MBs) are used as the inner core. Au core-Ag shell nanorods (Au@Ag NRs) are employed as the SERS generators and attached on the silica-coated MBs. After burying these Au@Ag NRs with another silica layer, CdTe quantum dots (QDs), that is, the fluorescent agent, are anchored onto the silica layer. Finally, antibodies are covalently linked to CdTe QDs. SFJSE is fulfilled by using different Raman molecules and QDs with different emission wavelengths. By utilizing four human cancer cell lines and one normal cell line as the model cells, the nanoprobes can specifically and simultaneously separate target cancer cells from the normal ones. This SFJSE-based method greatly facilitates the multiplex, rapid, and accurate cancer cell separation, and has a prosperous potential in high-throughput analysis and cancer diagnosis. PMID:24862088

Wang, Zhuyuan; Zong, Shenfei; Chen, Hui; Wang, Chunlei; Xu, Shuhong; Cui, Yiping

2014-11-01

163

Conjugates of magnetic nanoparticle-actinide specific chelator for radioactive waste separation.  

PubMed

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. PMID:24070142

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

2013-11-01

164

Separation of uranium from nitric and hydrochloric acid solutions with extractant-coated magnetic microparticles.  

SciTech Connect

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 (D{sub 2}EHPA or HDEHP) and were evaluated for the separation of uranyl ions from nitric- and hydrochloric-acid solutions. The results suggest that a synergistic interaction between the particle surface and solvent coating may explain why the particles display, in some cases, orders of magnitude of higher partitioning coefficients than are estimated from solvent-extraction measurements. Particles coated with TBP and those coated with a combination of TOPO and D{sub 2}EHPA displayed the most desirable characteristics for removing uranium from dilute acid environments typical of contaminated groundwater. Uranium separation from moderate to highly acidic waste streams typical of Department of Energy (DOE) nuclear wastes is best accomplished using particles coated with a combination of CMPO and TBP.

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

2000-01-01

165

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

SciTech Connect

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

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

2000-11-01

166

Structural studies, magnetic properties and loss separation in iron–phenolicsilane soft magnetic composites  

Microsoft Academic Search

In this work, six different series of iron based soft magnetic composites are produced and studied: (1) passive iron powder; (2) passive iron powder-0.7% resin with coupling agent; (3) passive iron powder-0.7% resin without coupling agent; (4) passive iron powder-1.5% resin with coupling agent; (5) passive iron powder-1.5% resin without coupling agent; (6) pure iron-1.5% resin. The specimens were shaped

A. H. Taghvaei; H. Shokrollahi; K. Janghorban

2010-01-01

167

Core-shell magnetic nanoparticles: a comparative study based on silica and polydopamine coating for magnetic bio-separation platforms.  

PubMed

Core-shell magnetic nanoparticles (MNPs) offer tremendous opportunities in a large range of applications in biomedicine due to their superior magnetic properties, biocompatibility and suitability for modification. In most cases, these characteristic features are determined by their shell chemistry and morphology. Herein, we demonstrate a comparative study of silica and polydopamine (PDOP) coating onto MNP surfaces based on synthesis, characterization and usage in a bio-separation platform. It was found that monodispersed MNPs may be easily obtained on silica coating of varying shell thickness, whereas a continuous PDOP layer observed around the MNPs prevents the formation of the dispersed form. On the other hand, PDOP coated MNPs exhibited better superparamagnetic behavior and biological modification ability compared to the silica coated form. PMID:23050265

Sahin, Ferat; Turan, Eylem; Tumturk, Hayrettin; Demirel, Gokhan

2012-12-01

168

Cryo-Electron Tomography for Structural Characterization of Macromolecular Complexes  

PubMed Central

Cryo-electron tomography (cryo-ET) is an emerging 3-D reconstruction technology that combines the principles of tomographic 3-D reconstruction with the unmatched structural preservation of biological material embedded in vitreous ice. Cryo-ET is particularly suited to investigating cell-biological samples and large macromolecular structures that are too polymorphic to be reconstructed by classical averaging-based 3-D reconstruction procedures. This unit aims to make cryo-ET accessible to newcomers and discusses the specialized equipment required, as well as the relevant advantages and hurdles associated with sample preparation by vitrification and cryo-ET. Protocols describe specimen preparation, data recording and 3-D data reconstruction for cryo-ET, with a special focus on macromolecular complexes. A step-by-step procedure for specimen vitrification by plunge freezing is provided, followed by the general practicalities of tilt-series acquisition for cryo-ET, including advice on how to select an area appropriate for acquiring a tilt series. A brief introduction to the underlying computational reconstruction principles applied in tomography is described, along with instructions for reconstructing a tomogram from cryo-tilt series data. Finally, a method is detailed for extracting small subvolumes containing identical macromolecular structures from tomograms for alignment and averaging as a means to increase the signal-to-noise ratio and eliminate missing wedge effects inherent in tomographic reconstructions. PMID:21842467

Cope, Julia; Heumann, John; Hoenger, Andreas

2011-01-01

169

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

170

2D modeling and preliminary in vitro investigation of a prototype high gradient magnetic separator for biomedical applications.  

PubMed

High gradient magnetic separation (HGMS) of magnetic materials from fluids or waste products has many established industrial applications. However, there is currently no technology employing HGMS for ex-vivo biomedical applications, such as for the removal of magnetic drug- or toxin-loaded spheres from the human blood stream. Importantly, human HGMS applications require special design modifications as, in contrast to conventional use where magnetic elements are permanently imbedded within the separation chambers, medical separators need to avoid direct contact between the magnetic materials and blood to reduce the risk of blood clotting and to facilitate convenient and safe treatment access for many individuals. We describe and investigate the performance of a magnetic separator prototype designed for biomedical applications. First, the capture efficiency of a prototype HGMS separator unit consisting of a short tubing segment and two opposing magnetizable fine wires along the outside of the tubing was investigated using 2D mathematical modeling. Second, the first-pass effectiveness to remove commercially available, magnetic polystyrene spheres from human blood using a single separator unit was experimentally verified. The theoretical and experimental data correlated well at low flow velocities (<5.0 cm/s) and high external magnetic fields (>0.05 T). This prototype separator unit removed >90% in a single pass of the magnetic spheres from water at mean flow velocity < or =8.0 cm/s and from blood mimic fluids (ethylene glycol-water solutions) at mean flow velocity < or =2.0 cm/s. In summary, we describe and prove the feasibility of a HGMS separator for biomedical applications. PMID:17400018

Chen, Haitao; Kaminski, Michael D; Rosengart, Axel J

2008-01-01

171

Isolation of primary mouse retinal ganglion cells using immunopanning-magnetic separation  

PubMed Central

Purpose To establish an effective system for isolating primary retinal ganglion cells (RGCs) from newborn mice. Methods The retinas were separated from enucleated eyeballs of Crl:CD-1 mice on postnatal day 1 to 4. RGCs were purified using three different methods, including two-step immunopanning (TSI), direct magnetic separation (DMS), and immunopanning-magnetic separation (IMS). Harvested cells were maintained for 24 h in a defined medium and then examined with immunocytochemistry, western immunoblotting, and real-time reverse transcription polymerase chain reaction (RT-PCR) for glial cell–specific glial fibrillary acidic protein (GFAP) and amacrine cell-specific syntaxin 1. Results As determined with immunofluorescence staining, RGCs purified by TSI were sparsely mixed with GFAP-positive astrocytes, and RGCs isolated by DMS were frequently mixed with syntaxin 1-positive amacrine cells. However, RGCs collected by IMS were seldom contaminated by GFAP-positive or syntaxin 1-positive cells. On western immunoblots, TSI cells showed significant GFAP expression, and DMS cells showed apparent syntaxin 1 expression, but IMS cells did not. Results of the real-time RT–PCR showed a similar tendency to those of the immunocytochemistry and western immunoblots. Conclusion Primary mouse RGCs were highly purified by the IMS method, combining the benefits of the TSI and DMS methods. This isolation method may provide a good experimental system for studying glaucoma in vitro. PMID:23233794

Iizuka, Yoko; Kim, Chan Yun; Seong, Gong Je

2012-01-01

172

Cocaine detection via rolling circle amplification of short DNA strand separated by magnetic beads.  

PubMed

A novel and sensitive fluorescence biosensor based on aptamer and rolling circle amplification for the determination of cocaine was developed in the present work. Here cocaine aptamers immobilized onto Au nanoparticles modified magnetic beads hybridized with short DNA strand. In the presence of cocaine, the short DNA strand was displaced from aptamer owing to cocaine specially binding with aptamer. Next, the short DNA strand was separated by magnetic beads and used to originate rolling circle amplification as primer. The end products of rolling circle amplification were detected by fluorescence signal generation upon molecular beacons hybridizing with the end products of rolling circle amplification. With rolling circle amplification and the separation by magnetic beads reducing the background signal, the new strategy was suitable for the detection of as low as 0.48 nM cocaine. Compared with reported cocaine sensors, our method exhibited excellent sensitivity. Our new strategy may provide a platform for numerous proteins and low molecular weight analytes to highly sensitively detect by DNA amplification. PMID:21277763

Ma, Cuiping; Wang, Wenshuo; Yang, Qing; Shi, Chao; Cao, Lijie

2011-03-15

173

Separation and measurement of silver nanoparticles and silver ions using magnetic particles.  

PubMed

The recent surge in consumer products and applications using metallic nanoparticles has increased the possibility of human or ecosystem exposure due to unintentional release into the environment. To protect consumer health and the environment, there is an urgent need to develop tools that can characterize and quantify these materials at low concentrations and in complex matrices. In this study, magnetic nanoparticles coated with either dopamine or glutathione were used to develop a new, simple and reliable method for the separation/pre-concentration of trace amounts of silver nanoparticles followed by their quantification using inductively coupled plasma mass spectrometry (ICP-MS). The structurally modified magnetic particles were able to capture trace amounts of silver nanoparticles (~2 ppb) and concentrate (up to 250 times) the particles for analysis with ICP-MS. Under laboratory conditions, recovery of silver nanoparticles was >99%. More importantly, the magnetic particles selectively captured silver nanoparticles in a mixture containing both nano-particulate and ionic silver. This unique feature addresses the challenges of separation and quantification of silver nanoparticles in addition to the total silver in environmental samples. Spiking experiments showed recoveries higher than 97% for tap water and both fresh and saline surface water. PMID:24295749

Mwilu, Samuel K; Siska, Emily; Baig, R B Nasir; Varma, Rajender S; Heithmar, Ed; Rogers, Kim R

2014-02-15

174

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. PMID:20712781

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

175

Chemical separation of primordial Li+ during structure formation caused by nanogauss magnetic field  

NASA Astrophysics Data System (ADS)

During the structure formation, charged and neutral chemical species may have separated from each other at the gravitational contraction in primordial magnetic field (PMF). A gradient in the PMF in a direction perpendicular to the field direction leads to the Lorentz force on the charged species. Resultantly, an ambipolar diffusion occurs, and charged species can move differently from neutral species, which collapses gravitationally during the structure formation. We assume a gravitational contraction of neutral matter in a spherically symmetric structure, and calculate fluid motions of charged and neutral species. It is shown that the charged fluid, i.e. proton, electron, and 7Li+, can significantly decouple from the neutral fluid depending on the field amplitude. The charged species can, therefore, escape from the gravitational collapse. We take the structure mass, the epoch of the gravitational collapse, and the comoving Lorenz force as parameters. We then identify a parameter region for an effective chemical separation. This type of chemical separation can reduce the abundance ratio of Li/H in early structures because of inefficient contraction of 7Li+ ion. Therefore, it may explain Li abundances of Galactic metal-poor stars which are smaller than the prediction in standard big bang nucleosynthesis model. Amplitudes of the PMFs are controlled by a magnetohydrodynamic turbulence. The upper limit on the field amplitude derived from the turbulence effect is close to the value required for the chemical separation.

Kusakabe, Motohiko; Kawasaki, Masahiro

2015-01-01

176

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

177

TREATMENT OF COMBINED SEWER OVERFLOWS BY HIGH GRADIENT MAGNETIC SEPARATION. ON-SITE TESTING WITH MOBILE PILOT PLANT TRAILER  

EPA Science Inventory

Seeded water treatment using a SALA high gradient magnetic separator pilot plant system was conducted on combined sewer overflows and raw sewage at SALA Magnetics in Cambridge, MA and at on-site locations in the Boston area. Special emphasis was placed on specific design and oper...

178

IMPROVEMENT OF MAGNETICALLY SEPARATED FERROUS CONCENTRATE BY SHREDDING: A PERFORMANCE TEST. TEST NO. 4.07, RECOVERY 1, NEW ORLEANS  

EPA Science Inventory

This report describes a series of test runs in which ferrous product magnetically recovered from municipal waste was further shredded in a small (50 hp) hammermill to free attached or entrapped contaminant. A belt magnet was then used to separate metal from the liberated contamin...

179

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

PubMed

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

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

2013-06-01

180

Upgrading of PVC rich wastes by magnetic density separation and hyperspectral imaging quality control.  

PubMed

Polyvinylchloride (PVC) is one of the most produced polymers in Europe, with a share of 11% in terms of mass (8 milliontons) of total polymer consumption, but in 2010 only 5% of the total PVC production came from recycled materials, where other polymer recycling achieves a level of 15% on average. In order to find an innovative process to extract PVC from window frames waste, a combination of two innovative technologies was tested: magnetic density separation (MDS) and hyperspectral imaging (HSI). By its nature, MDS is a flexible high precision density separation technology that is applicable to any mixture of polymers and contaminants with non-overlapping densities. As PVC has a very distinctive high density, this technology was tested to obtain high-grade PVC pre-concentrates from window frame waste. HSI was used to perform a quality control of the products obtained by MDS showing that PVC was clearly discriminated from unwanted rubber particles of different colors. The results showed that the combined application of MDS and HSI techniques allowed to separate and to check the purity of PVC from window frame waste. PMID:25458764

Luciani, Valentina; Bonifazi, Giuseppe; Rem, Peter; Serranti, Silvia

2014-11-01

181

Temperature dependence of iron local magnetic moment in phase-separated superconducting chalcogenide  

NASA Astrophysics Data System (ADS)

We have studied local magnetic moment and electronic phase separation in superconducting KxFe2 -ySe2 by x-ray emission and absorption spectroscopy. Detailed temperature-dependent measurements at the Fe K-edge have revealed coexisting electronic phases and their correlation with the transport properties. By cooling down, the local magnetic moment of Fe shows a sharp drop across the superconducting transition temperature (Tc) and the coexisting phases exchange spectral weights with the low-spin state, gaining intensity at the expense of the higher-spin state. After annealing the sample across the iron-vacancy order temperature, the system does not recover the initial state and the spectral weight anomaly at Tc as well as superconductivity disappear. The results clearly underline that the coexistence of the low-spin and high-spin phases and the transitions between them provide unusual magnetic fluctuations and have a fundamental role in the superconducting mechanism of the electronically inhomogeneous KxFe2 -ySe2 system.

Simonelli, L.; Mizokawa, T.; Sala, M. Moretti; Takeya, H.; Mizuguchi, Y.; Takano, Y.; Garbarino, G.; Monaco, G.; Saini, N. L.

2014-12-01

182

Mass separation of a multi-component plasma flow travelling through a magnetic transport system  

NASA Astrophysics Data System (ADS)

The travel of plasma flow produced by a dc arc through a transport system based on a curved magnetic field was studied. The characteristics of the system were the absence of a curved metallic plasma guiding duct ('open architecture') and the fact that the magnetic field coils were non-coaxial to the plasma flow. By means of Langmuir probe measurements it was shown that both shape and position of the cathode plasma flow at the exit of the transport system were governed by variation of currents of the magnetic coils as well as by biasing of a special electrode inserted into the plasma flow. It was found that with parameters of the transport system held constant, the plasma ions with lower m/Z were deflected more, e.g. Al ions were deflected more than Ti ions. For an arc with a composite cathode, consisting of mainly Cr-Fe-Ni, the profile of atoms of these elements at the exit of the transport system was measured by x-ray fluorescence spectrometry. The results obtained were consistent with the probe measurements, hence the transport system, in principle, may be used for spatial separation of a multi-component (in masses) plasma flow.

Paperny, V. L.; Krasov, V. I.; Lebedev, N. V.; Astrakchantsev, N. V.

2011-06-01

183

Collaborative Computational Project for Electron cryo-Microscopy  

PubMed Central

The Collaborative Computational Project for Electron cryo-Microscopy (CCP-EM) has recently been established. The aims of the project are threefold: to build a coherent cryoEM community which will provide support for individual scientists and will act as a focal point for liaising with other communities, to support practising scientists in their use of cryoEM software and finally to support software developers in producing and disseminating robust and user-friendly programs. The project is closely modelled on CCP4 for macromolecular crystallo­graphy, and areas of common interest such as model fitting, underlying software libraries and tools for building program packages are being exploited. Nevertheless, cryoEM includes a number of techniques covering a large range of resolutions and a distinct project is required. In this article, progress so far is reported and future plans are discussed. PMID:25615866

Wood, Chris; Burnley, Tom; Patwardhan, Ardan; Scheres, Sjors; Topf, Maya; Roseman, Alan; Winn, Martyn

2015-01-01

184

Separation of semiconducting and ferromagnetic FeSi2-nanoparticles by magnetic filtering  

NASA Astrophysics Data System (ADS)

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

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

2013-10-01

185

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

NASA Astrophysics Data System (ADS)

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

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

2012-12-01

186

Arctic experiments to support CryoSat-2 validation  

NASA Astrophysics Data System (ADS)

Validating the elevation retrievals from a phase coherent pulse-width limited polar observing radar altimeter such as the Synthestic/interferometric radar altimeter (SIRAL), the primary payload of CryoSat, is not a simple one. In order to fully understand all the respective error co-variances it is necessary to acquire and correlate many different types of in-situ measurements (GPR, neutron probe density profiles, drilled and electromagnetic derived sea-ice thicknesses, for example) in highly inhospitable regions of the cryosphere at key times of the year. In order to correlate retrievals from CryoSat with other airborne and in-situ data it was decided early in the CryoSat development that an aircraft borne radar altimeter with similar functionality to SIRAL would provide the necessary link, albeit on the smaller scale, and provide pre-launch incite into expected performances and logistical difficulties. In 2001 ESA commenced the development of its own prototype radar altimeter that mimics the functionality of SIRAL. Similar to SIRAL, but with subtle functional differences, the airborne SAR/Interferometric Radar Altimeter System (ASIRAS). has now been the centre piece instrument for a number of large scale land and sea ice field campaigns in the Arctic during spring and autumn 2004, 2006 and 2008 known as CryoVEx (CryoSat validation experiment). Additional smaller science/test campaigns have taken place in March 2003 (Svalbard), March 2005 (Bay of Bothnia), March 2006 (Western Greenland), April 2007 (CryoVEx 2007 in Svalbard). It is a credit to all international parties in the CryoSat Validation and Retrieval Team (CVRT) for the coordination, planning, acquisition of in-situ and airborne measurements and the subsequent processing and distributing of its data for analysis. The CVRT has an infrastructure ready for validating CryoSat-2. This paper describes the different measurements acquired, the key science results and stresses the importance of the campaigns to date (despite the loss of CryoSat-1 in Oct 2005 due to launcher failure) and those planned following CryoSat-2 launch in 2009.

Cullen, R.; Davidson, M. W. J.

2009-04-01

187

CAPTURE AND RETRIEVAL OF PLUTONIUM OXIDE PARTICLES AT ULTRA-LOW CONCENTRATIONS USING HIGH-GRADIENT MAGNETIC SEPARATION  

Microsoft Academic Search

A high-gradient magnetic separation system has been developed for capture and retrieval of ultra-low plutonium oxide concentrations. The application of advanced matrix materials and improved methodology has demonstrated the effective collection and recovery of submicron paramagnetic actinide particles with particle concentrations as low as 10 M. Incorporation of multiple passes during recovery of magnetically captured particles improves the system mass balance.

Robert M. Wingo; David J. Devlin; Dallas D. Hill; Dennis D. Padilla; F. Coyne Prenger; Laura A. Worl

2002-01-01

188

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

PubMed

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

Furlan, Marco; Lattuada, Marco

2012-08-28

189

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. PMID:23688064

2013-01-01

190

Beam-Energy Dependence of Charge Separation Along the Magnetic Field in Au + Au Collisions at RHIC  

E-print Network

Local parity-odd domains are theorized to form inside a quark-gluon plasma which has been produced in high-energy heavy-ion collisions. The local parity-odd domains manifest themselves as charge separation along the magnetic ...

Stevens, Justin

191

MAGNETIC DRUM SEPARATOR PERFORMANCE SCALPING TROMMEL UNDERFLOW AT NOMINAL DESIGN CONDITIONS. TEST NO. 4.01, RECOVERY 1, NEW ORLEANS  

EPA Science Inventory

This report describes the first test of the magnetic drum separator that was designed to scalp the underflow of the trommel, or rotary screen, at the New Orleans, Louisiana, resource recovery facility. The objective of the test was to document the performance of the trommel-under...

192

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...

193

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

194

Environmental friendly crush-magnetic separation technology for recycling metal-plated plastics from end-of-life vehicles.  

PubMed

Metal-plated plastics (MPP), which are important from the standpoint of aesthetics or even performance, are increasingly employed in a wide variety of situations in the automotive industry. Serious environmental problems will be caused if they are not treated appropriately. Therefore, recycling of MPP is an important subject not only for resource recycling but also for environmental protection. This work represents a novel attempt to deal with the MPP. A self-designed hammer crusher was used to liberate coatings from the plastic substrate. The size distribution of particles was analyzed and described by the Rosin-Rammler function model. The optimum retaining time of materials in the crusher is 3 min. By this time, the liberation rate of the materials can reach 87.3%. When the density of the suspension is 31,250 g/m(3), the performance of liberation is the best. Two-step magnetic separation was adopted to avoid excessive crushing and to guarantee the quality of products. Concerning both the separation efficiency and grade of products, the optimum rotational speed of the magnetic separator is 50-70 rpm. On the basis of the above studies about the liberating and separating behavior of the materials, a continuous recycling system (the technology of crush-magnetic separation) is developed. This recycling system provides a feasible method for recycling MPP efficiently, economically, and environmentally. PMID:22304328

Xue, Mianqiang; Li, Jia; Xu, Zhenming

2012-03-01

195

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

196

Ferrimagnetism and magnetic phase separation in Nd1-xYxMnO3 studied by magnetization and high frequency electron paramagnetic resonance  

NASA Astrophysics Data System (ADS)

Ferrimagnetism and metamagnetic features tunable by composition are observed in the magnetic response of Nd1-xYxMnO3, for x=0.1-0.5. For all values of x in the series, the compound crystallizes in orthorhombic Pbnm space group similar to NdMnO3. Magnetization studies reveal a phase transition of the Mn-sublattice below T N Mn ? 80 K for all compositions, which, decreases up on diluting the Nd-site with Yttrium. For x=0.35, ferrimagnetism is observed. At 5 K, metamagnetic transition is observed for all compositions x < 0.4. The evolution of magnetic ground states and appearance of ferrimagnetism in Nd1-xYxMnO3 can be accounted for by invoking the scenario of magnetic phase separation. The high frequency electron paramagnetic resonance measurements on x=0.4 sample, which is close to the critical composition for phase separation, revealed complex temperature dependent lineshapes clearly supporting the assumption of magnetic phase separation.

Nair, Harikrishnan S.; Yadav, Ruchika; Adiga, Shilpa; Rao, S. S.; van Tol, Johan; Elizabeth, Suja

2015-01-01

197

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

198

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

PubMed

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

Piao, Chunying; Chen, Ligang

2012-12-14

199

Magnetic counter-gravity flow separation of electrically prepolarised lymphoid cells.  

PubMed

A novel principle is proposed for a differential separation of live cells (such as leucocytes) from a main flow. A microfluidic device with planar insulated electrodes as the side walls of the channel was manufactured and tested. An array of insulated vertical conductor wires was inserted along the axis of the channel and used to impose Lorentz forces upon polarisable particles that moved with the flow. Polystyrene microspheres and lymphoid cell lines (DOHH2 and K562) were used to test the ability of the setting to impose a force field that induced consistent vertical motion. The direction of electric current was found to directly influence the number of cells or microspheres that were sampled at the surface of the flow. Lorentz force was considered to be active upon cells due to an overall polarisation of the membrane surface. The consequence of the magnetic force was that the polarised cells were moved vertically upwards (opposing gravity). The setting was effective for increasing the number of extracted cells from a main flow or for increasing the concentration of DOHH2 cells in a mixed population with K562 in culture medium. The limitations of the work parameters (potential-current) were found to be dependent upon the cell type. PMID:17278260

Popa, C; Su, B; Vadgama, P; Cotter, F

2007-02-01

200

3D Structure Determination of Native Mammalian Cells using Cryo-FIB and Cryo-electron Tomography  

PubMed Central

Cryo-electron tomography (cryo-ET) has enabled high resolution three-dimensional (3D) structural analysis of virus and host cell interactions and many cell signaling events; these studies, however, have largely been limited to very thin, peripheral regions of eukaryotic cells or to small prokaryotic cells. Recent efforts to make thin, vitreous sections using cryo-ultramicrotomy have been successful, however, this method is technically very challenging and with many artifacts. Here, we report a simple and robust method for creating in situ, frozen-hydrated cell lamellas using a focused ion beam at cryogenic temperature (cryo-FIB), allowing access to any interior cellular regions of interest. We demonstrate the utility of cryo-FIB with high resolution 3D cellular structures from both bacterial cells and large mammalian cells. The method will not only facilitate high-throughput 3D structural analysis of biological specimens, but is also broadly applicable to sample preparation of thin films and surface materials without the need for FIB “lift-out”. PMID:22796867

Wang, Ke; Strunk, Korrinn; Zhao, Gongpu; Gray, Jennifer L.; Zhang, Peijun

2012-01-01

201

Analyses of Subnanometer Resolution Cryo-EM Density Maps  

PubMed Central

Today, electron cryomicroscopy (cryo-EM) can routinely achieve subnanometer resolutions of complex macromolecular assemblies. From a density map, one can extract key structural and functional information using a variety of computational analysis tools. At subnanometer resolution, these tools make it possible to isolate individual subunits, identify secondary structures, and accurately fit atomic models. With several cryo-EM studies achieving resolutions beyond 5 Å, computational modeling and feature recognition tools have been employed to construct backbone and atomic models of the protein components directly from a density map. In this chapter, we describe several common classes of computational tools that can be used to analyze and model subnanometer resolution reconstructions from cryo-EM. A general protocol for analyzing subnanometer resolution density maps is presented along with a full description of steps used in analyzing the 4.3 Å resolution structure of Mm-cpn. PMID:20888467

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

2011-01-01

202

Fluorescence cryo-microscopy: current challenges and prospects.  

PubMed

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. PMID:24951858

Kaufmann, Rainer; Hagen, Christoph; Grünewald, Kay

2014-06-01

203

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

204

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

205

Validation Experiments supporting the CryoSat-2 mission  

NASA Astrophysics Data System (ADS)

The primary goals of CryoSat are to derive improved estimates of the rates of change concerning land ice elevation and sea ice thickness and freeboard of the Earth’s land and marine ice fields. Validating such retrievals derived from a phase coherent pulse-width limited polar observing radar altimeter such as SIRAL, the primary payload of CryoSat, is not a simple one. In order to understand all the respective error co-variances it is necessary to acquire many different types of in-situ measurements (GPR, neutron probe density profiles, drilled and electromagnetic derived sea-ice thicknesses, for example) in highly inhospitable regions of the cryosphere at times of the year to detect relevant signals. In order to correlate retrievals from CryoSat with the in-situ data it was decided early in the CryoSat development that an aircraft borne radar altimeter with similar functionality to SIRAL would provide the necessary link, albeit on the smaller scale, and provide pre-launch incite into expected performances. In 2001 ESA commenced the development of its own prototype radar altimeter that mimics the functionality of SIRAL to be operated along-side an airborne laser scanner. Similar to SIRAL, but with subtle functional differences, the airborne SAR/Interferometric Radar Altimeter System (ASIRAS) has now been the centre piece instrument for a number of large scale land and sea ice field campaigns in the Arctic during spring and autumn 2004 and 2006 and 2008. Additional smaller science/test campaigns have taken place in March 2003 (Svalbard), March 2005 (Bay of Bothnia), March 2006 (Western Greenland) and April 2007 (CryoVEx 2007 in Svalbard). It is a credit to all parties that constitute the CryoSat Validation and Retrieval Team (CVRT) for the coordination, planning, acquisition of in-situ and airborne measurements and the subsequent processing and distributing of its data for analysis. CVRT has a robust infrastructure in place for validating and providing measures of uncertainty for its level 2 products derived from an operational CryoSat-2. This paper describes the different types of measurements, the key science results to date and we stress the importance of the next campaigns following the CryoSat-2 launch early in 2010.

Cullen, R.; Davidson, M.; Wingham, D.

2009-12-01

206

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. PMID:18077822

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

2009-01-01

207

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

208

Natural circulation loop using liquid nitrogen for cryo-detection system  

SciTech Connect

The natural circulation loop is designed for the cryogenic insert in a Fourier transform ion cyclotron resonance (FTICR) mass spectrometer. Sensitivity is the key parameter of a FTICR mass spectrometer and the cryo-cooling of the pre-amplifier can reduce the thermal noise level and thereby improve the signal-to-noise ratio. The pre-amplifier consisted of non-magnetic materials is thermally connected to the cooling loop which is passing through the flange maintaining ultra-high vacuum in the ion cell. The liquid nitrogen passes through inside of the loop to cool the pre-amplifier indirectly. At the end, a cryocooler is located to re-condense nitrogen vapor generated due to the heat from the pre-amplifier. The circulating fluid removes heat from the pre-amplifier and transports it to the cryocooler or heat sink. In this paper the natural circulation loop for cryogenic pre-amplifier is introduced for improving the sensitivity of cryo-detector. In addition, the initial cool-down of the system by a cryocooler is presented and the temperature of the radiation shield is discussed with respect to the thickness of shield and the thermal radiation load.

Choi, Yeon Suk [Korea Basic Science Institute, 169-148 Gwahak-ro, Yuseong-gu, Daejeon, 305-806 (Korea, Republic of)

2014-01-29

209

Navigation for fluoroscopy-guided cryo-balloon ablation procedures of atrial fibrillation  

NASA Astrophysics Data System (ADS)

Atrial fibrillation (AFib), the most common arrhythmia, has been identified as a major cause of stroke. The current standard in interventional treatment of AFib is the pulmonary vein isolation (PVI). PVI is guided by fluoroscopy or non-fluoroscopic electro-anatomic mapping systems (EAMS). Either classic point-to-point radio-frequency (RF)- catheter ablation or so-called single-shot-devices like cryo-balloons are used to achieve electrically isolation of the pulmonary veins and the left atrium (LA). Fluoroscopy-based systems render overlay images from pre-operative 3-D data sets which are then merged with fluoroscopic imaging, thereby adding detailed 3-D information to conventional fluoroscopy. EAMS provide tracking and visualization of RF catheters by means of electro-magnetic tracking. Unfortunately, current navigation systems, fluoroscopy-based or EAMS, do not provide tools to localize and visualize single shot devices like cryo-balloon catheters in 3-D. We present a prototype software for fluoroscopy-guided ablation procedures that is capable of superimposing 3-D datasets as well as reconstructing cyro-balloon catheters in 3-D. The 3-D cyro-balloon reconstruction was evaluated on 9 clinical data sets, yielded a reprojected 2-D error of 1.72 mm +/- 1.02 mm.

Bourier, Felix; Brost, Alexander; Kleinoeder, Andreas; Kurzendorfer, Tanja; Koch, Martin; Kiraly, Attila; Schneider, Hans-Juergen; Hornegger, Joachim; Strobel, Norbert; Kurzidim, Klaus

2012-02-01

210

Beam-energy dependence of charge separation along the magnetic field in Au+Au collisions at RHIC  

E-print Network

Local parity-odd domains are theorized to form inside a Quark-Gluon-Plasma (QGP) which has been produced in high-energy heavy-ion collisions. The local parity-odd domains manifest themselves as charge separation along the magnetic field axis via the chiral magnetic effect (CME). The experimental observation of charge separation has previously been reported for heavy-ion collisions at the top RHIC energies. In this paper, we present the results of the beam-energy dependence of the charge correlations in Au+Au collisions at midrapidity for center-of-mass energies of 7.7, 11.5, 19.6, 27, 39 and 62.4 GeV from the STAR experiment. After background subtraction, the signal gradually reduces with decreased beam energy, and tends to vanish by 7.7 GeV. The implications of these results for the CME will be discussed.

STAR Collaboration; L. Adamczyk; J. K. Adkins; G. Agakishiev; M. M. Aggarwal; Z. Ahammed; I. Alekseev; J. Alford; C. D. Anson; A. Aparin; D. Arkhipkin; E. C. Aschenauer; G. S. Averichev; A. Banerjee; D. R. Beavis; R. Bellwied; A. Bhasin; A. K. Bhati; P. Bhattarai; H. Bichsel; J. Bielcik; J. Bielcikova; L. C. Bland; I. G. Bordyuzhin; W. Borowski; J. Bouchet; A. V. Brandin; S. G. Brovko; S. Bültmann; I. Bunzarov; T. P. Burton; J. Butterworth; H. Caines; M. Calderón de la Barca Sánchez; D. Cebra; R. Cendejas; M. C. Cervantes; P. Chaloupka; Z. Chang; S. Chattopadhyay; H. F. Chen; J. H. Chen; L. Chen; J. Cheng; M. Cherney; A. Chikanian; W. Christie; J. Chwastowski; M. J. M. Codrington; G. Contin; J. G. Cramer; H. J. Crawford; X. Cui; S. Das; A. Davila Leyva; L. C. De Silva; R. R. Debbe; T. G. Dedovich; J. Deng; A. A. Derevschikov; R. Derradi de Souza; S. Dhamija; B. di Ruzza; L. Didenko; C. Dilks; F. Ding; P. Djawotho; X. Dong; J. L. Drachenberg; J. E. Draper; C. M. Du; L. E. Dunkelberger; J. C. Dunlop; L. G. Efimov; J. Engelage; K. S. Engle; G. Eppley; L. Eun; O. Evdokimov; O. Eyser; R. Fatemi; S. Fazio; J. Fedorisin; P. Filip; E. Finch; Y. Fisyak; C. E. Flores; C. A. Gagliardi; D. R. Gangadharan; D. Garand; F. Geurts; A. Gibson; M. Girard; S. Gliske; L. Greiner; D. Grosnick; D. S. Gunarathne; Y. Guo; A. Gupta; S. Gupta; W. Guryn; B. Haag; A. Hamed; L-X. Han; R. Haque; J. W. Harris; S. Heppelmann; A. Hirsch; G. W. Hoffmann; D. J. Hofman; S. Horvat; B. Huang; H. Z. Huang; X. Huang; P. Huck; T. J. Humanic; G. Igo; W. W. Jacobs; H. Jang; E. G. Judd; S. Kabana; D. Kalinkin; K. Kang; K. Kauder; H. W. Ke; D. Keane; A. Kechechyan; A. Kesich; Z. H. Khan; D. P. Kikola; I. Kisel; A. Kisiel; D. D. Koetke; T. Kollegger; J. Konzer; I. Koralt; L. K. Kosarzewski; L. Kotchenda; A. F. Kraishan; P. Kravtsov; K. Krueger; I. Kulakov; L. Kumar; R. A. Kycia; M. A. C. Lamont; J. M. Landgraf; K. D. Landry; J. Lauret; A. Lebedev; R. Lednicky; J. H. Lee; M. J. LeVine; C. Li; W. Li; X. Li; X. Li; Y. Li; Z. M. Li; M. A. Lisa; F. Liu; T. Ljubicic; W. J. Llope; M. Lomnitz; R. S. Longacre; X. Luo; G. L. Ma; Y. G. Ma; D. M. M. D. Madagodagettige Don; D. P. Mahapatra; R. Majka; S. Margetis; C. Markert; H. Masui; H. S. Matis; D. McDonald; T. S. McShane; N. G. Minaev; S. Mioduszewski; B. Mohanty; M. M. Mondal; D. A. Morozov; M. K. Mustafa; B. K. Nandi; Md. Nasim; T. K. Nayak; J. M. Nelson; G. Nigmatkulov; L. V. Nogach; S. Y. Noh; J. Novak; S. B. Nurushev; G. Odyniec; A. Ogawa; K. Oh; A. Ohlson; V. Okorokov; E. W. Oldag; D. L. Olvitt Jr.; M. Pachr; B. S. Page; S. K. Pal; Y. X. Pan; Y. Pandit; Y. Panebratsev; T. Pawlak; B. Pawlik; H. Pei; C. Perkins; W. Peryt; P. Pile; M. Planinic; J. Pluta; N. Poljak; K. Poniatowska; J. Porter; A. M. Poskanzer; N. K. Pruthi; M. Przybycien; P. R. Pujahari; J. Putschke; H. Qiu; A. Quintero; S. Ramachandran; R. Raniwala; S. Raniwala; R. L. Ray; C. K. Riley; H. G. Ritter; J. B. Roberts; O. V. Rogachevskiy; J. L. Romero; J. F. Ross; A. Roy; L. Ruan; J. Rusnak; O. Rusnakova; N. R. Sahoo; P. K. Sahu; I. Sakrejda; S. Salur; J. Sandweiss; E. Sangaline; A. Sarkar; J. Schambach; R. P. Scharenberg; A. M. Schmah; W. B. Schmidke; N. Schmitz; J. Seger; P. Seyboth; N. Shah; E. Shahaliev; P. V. Shanmuganathan; M. Shao; B. Sharma; W. Q. Shen; S. S. Shi; Q. Y. Shou; E. P. Sichtermann; R. N. Singaraju; M. J. Skoby; D. Smirnov; N. Smirnov; D. Solanki; P. Sorensen; H. M. Spinka; B. Srivastava; T. D. S. Stanislaus; J. R. Stevens; R. Stock; M. Strikhanov; B. Stringfellow; M. Sumbera; X. Sun; X. M. Sun; Y. Sun; Z. Sun; B. Surrow; D. N. Svirida; T. J. M. Symons; M. A. Szelezniak; J. Takahashi; A. H. Tang; Z. Tang; T. Tarnowsky; J. H. Thomas; A. R. Timmins; D. Tlusty; M. Tokarev; S. Trentalange; R. E. Tribble; P. Tribedy; B. A. Trzeciak; O. D. Tsai; J. Turnau; T. Ullrich; D. G. Underwood; G. Van Buren; G. van Nieuwenhuizen; M. Vandenbroucke; J. A. Vanfossen, Jr.; R. Varma; G. M. S. Vasconcelos; A. N. Vasiliev; R. Vertesi; F. Videbæk; Y. P. Viyogi; S. Vokal; A. Vossen; M. Wada; F. Wang; G. Wang; H. Wang; J. S. Wang; X. L. Wang; Y. Wang; Y. Wang; G. Webb; J. C. Webb; G. D. Westfall; H. Wieman; S. W. Wissink; R. Witt; Y. F. Wu; Z. Xiao; W. Xie; K. Xin; H. Xu; J. Xu; N. Xu; Q. H. Xu; Y. Xu; Z. Xu; W. Yan; C. Yang; Y. Yang; Y. Yang; Z. Ye; P. Yepes; L. Yi; K. Yip; I-K. Yoo; N. Yu; Y. Zawisza; H. Zbroszczyk; W. Zha; J. B. Zhang; J. L. Zhang; S. Zhang; X. P. Zhang; Y. Zhang; Z. P. Zhang; F. Zhao; J. Zhao; C. Zhong; X. Zhu; Y. H. Zhu; Y. Zoulkarneeva; M. Zyzak

2014-04-05

211

Status of the Superconducting Proton Linac (SPL) Cryo-Module  

E-print Network

The Superconducting Proton Linac (SPL) is an R&D effort conducted by CERN in partnership with other international laboratories, aimed at developing key technologies for the construction of a multi-megawatt proton linac based on state-of-the-art SRF technology. Such an accelerator could serve as a driver in new physics facilities for neutrinos and/or radioactive ion beams [1]. Amongst the main objectives of this effort, are the development of 704 MHz bulk niobium beta=1 elliptical cavities (operating at 2 K and providing an accelerating gradient of 25 MV/m) and the test of a string of cavities integrated in a machine-type cryo-module. In an initial phase, only four out of the eight cavities of the SPL cryo-module will be tested in a half-length cryo-module developed for this purpose, which nonetheless preserves the main features of the full size module. This paper presents the final design of the cryo-module and the status of the construction of the main cryostat parts. Preliminary plans for the assembly a...

Parma, V; Capatina, O; Chambrillon, J; Montesinos, E; Schirm, K; Vande Craen, A; Vandoni, G; Van Weelderen, R

2014-01-01

212

NASA Perspectives on Cryo H2 DOE Hydrogen Storage Workshop  

E-print Network

NASA Perspectives on Cryo H2 Storage DOE Hydrogen Storage Workshop Marriott Crystal Gateway Arlington, VA February 15, 2011 David J. Chato NASA Glenn Research Center Michael P. Doherty NASA Glenn Research Center #12;2 Objectives Purposes of this Presentation · To show the role of Cryogenics in NASA

213

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. PMID:22100448

Scheres, Sjors H.W.

2012-01-01

214

TESLA Report 2001-38 THE TESLA CRYO-PLANTS  

E-print Network

TESLA Report 2001-38 THE TESLA CRYO-PLANTS H. Quack, M. Kauschke, C. Haberstroh, TU Dresden, 01062 The Tera-eV Energy Superconducting Linear Accelerator (TESLA) is a 32 km long superconducting linear to higher complexity 4 Single component failure not leading to total plant shutdown Motor burnout, compr

215

Microstructure-mechanical property correlation of cryo rolled Zircaloy-4  

NASA Astrophysics Data System (ADS)

The evolution of microstructure and the mechanical properties of cryo-rolled Zircaloy-4 were both investigated to understand the origin of the alloy's strength processed at a cryogenic temperature. The correlation of dislocation density, grain size and yield stress of the rolled product indicated that an increase in dislocation density due to the suppression of dynamic recovery is the primary source of strengthening.

Sarkar, Apu; Murty, Korukonda L.

2015-01-01

216

Covariance Matrix Estimation for the Cryo-EM Heterogeneity Problem  

E-print Network

In cryo-electron microscopy (cryo-EM), a microscope generates a top view of a sample of randomly-oriented copies of a molecule. The cryo-EM problem is to use the resulting set of noisy 2D projection images taken at unknown directions to reconstruct the 3D structure of the molecule. In some situations, the molecule under examination exhibits structural variability, which poses a fundamental challenge in cryo-EM. The heterogeneity problem is the task of mapping the space of conformational states of a molecule. It has been previously shown that the leading eigenvectors of the covariance matrix of the 3D molecules can be used to solve the heterogeneity problem. Estimating the covariance matrix is however challenging, since only projections of the molecules are observed, but not the molecules themselves. In this paper, we derive an estimator for the covariance matrix as a solution to a certain linear system. The linear operator to be inverted, which we term the tomographic covariance transform, is an important obj...

Katsevich, Gene; Singer, Amit

2013-01-01

217

Magnetic hydroxyapatite nanoparticles: An efficient adsorbent for the separation and removal of nitrate and nitrite ions from environmental samples.  

PubMed

A novel type of magnetic nanosorbent, hydroxyapatite-coated Fe2 O3 nanoparticles was synthesized and used for the adsorption and removal of nitrite and nitrate ions from environmental samples. The properties of synthesized magnetic nanoparticles were characterized by scanning electron microscopy, Fourier transform infrared spectroscopy, and X-ray powder diffraction. After the adsorption process, the separation of ?-Fe2 O3 @hydroxyapatite nanoparticles from the aqueous solution was simply achieved by applying an external magnetic field. The effects of different variables on the adsorption efficiency were studied simultaneously using an experimental design. The variables of interest were amount of magnetic hydroxyapatite nanoparticles, sample volume, pH, stirring rate, adsorption time, and temperature. The experimental parameters were optimized using a Box-Behnken design and response surface methodology after a Plackett-Burman screening design. Under the optimum conditions, the adsorption efficiencies of magnetic hydroxyapatite nanoparticles adsorbents toward NO3 (-) and NO2 (-) ions (100 mg/L) were in the range of 93-101%. The results revealed that the magnetic hydroxyapatite nanoparticles adsorbent could be used as a simple, efficient, and cost-effective material for the removal of nitrate and nitrite ions from environmental water and soil samples. PMID:25376506

Ghasemi, Ensieh; Sillanpää, Mika

2015-01-01

218

Pathogen detection in complex samples by quartz crystal microbalance sensor coupled to aptamer functionalized core-shell type magnetic separation.  

PubMed

A quartz crystal microbalance sensor (QCM) was developed for sensitive and specific detection of Salmonella enterica serovar typhimurium cells in food samples by integrating a magnetic bead purification system. Although many sensor formats based on bioaffinity agents have been developed for sensitive and specific detection of bacterial cells, the development of robust sensor applications for food samples remained a challenging issue. A viable strategy would be to integrate QCM to a pre-purification system. Here, we report a novel and sensitive high throughput strategy which combines an aptamer-based magnetic separation system for rapid enrichment of target pathogens and a QCM analysis for specific and real-time monitoring. As a proof-of-concept study, the integration of Salmonella binding aptamer immobilized magnetic beads to the aptamer-based QCM system was reported in order to develop a method for selective detection of Salmonella. Since our magnetic separation system can efficiently capture cells in a relatively short processing time (less than 10min), feeding captured bacteria to a QCM flow cell system showed specific detection of Salmonella cells at 100CFUmL(-1) from model food sample (i.e., milk). Subsequent treatment of the QCM crystal surface with NaOH solution regenerated the aptamer-sensor allowing each crystal to be used several times. PMID:25467500

Ozalp, Veli C; Bayramoglu, Gulay; Erdem, Zehra; Arica, M Yakup

2015-01-01

219

Microfluidically Cryo-Cooled Planar Coils for Magnetic Resonance Imaging  

E-print Network

by 57 mm long planar RF coil and an imaging surface on which target samples to be imaged can be placed (Figure 1a). Poly(dimethylsiloxane) (PDMS, thermal conductivity = 0.18 W/mK) was used as the microchannel material. Since only a small amount...

Koo, Chiwan

2013-08-09

220

Phase separation and sharp magnetization steps in polycrystalline Pr 1- xCa xMnO 3  

NASA Astrophysics Data System (ADS)

Similar to the A-site and Mn-site substitution in orbital-charge ordered (OO-CO) polycrystalline Pr 0.5Ca 0.5MnO 3, the decrease in x from x=0.50 in Pr 1- xCa xMnO 3 can also induce sharp magnetization steps. It has been interpreted by a martensitic-like mechanism based on phase separation. With the decrease in x, the ideal Mn 3+/Mn 4+=1:1 orbital-charge ordering will be weakened, which is due to the disorder created by the extra Mn 3+ cations. Therefore, small ferromagnetic (FM) regions with higher symmetrical structure can be induced in the antiferromagnetic (AFM) OO-CO matrix with a strongly distorted structure. Due to their different symmetry, the strains will be created at the interface between the FM regions and the AFM matrix. In a magnetic field, the FM domains cannot grow continuously because of the existence of the interfacial strains. In order to achieve their further growth, a higher magnetic field must be applied to overcome the interfacial strains. As a result, sharp magnetization steps will appear in magnetization versus magnetic field curves of Pr 1- xCa xMnO 3. The x is smaller, the stability of the OO-CO phase is weaker, and then the interfacial strains become lower. Consequently, the critical magnetic field corresponding to the step appearance will decrease. Furthermore, the existence of the additional OO-CO state, which was recently reported by Asaka et al. [T. Asaka, S. Yamada, S. Tsutsumi, C. Tsuruta, K. Kimoto, T. Arima, T. Matsui, Phys. Rev. Lett. 88 (2002) 97201], has not been supported by our magnetic results and microscopic studies.

Zhu, Deliang; Cao, Peijiang; Maignan, A.; Raveau, B.

2007-10-01

221

High-resolution structure of the Shigella type-III secretion needle by solid-state NMR and cryo-electron microscopy.  

PubMed

We introduce a general hybrid approach for determining the structures of supramolecular assemblies. Cryo-electron microscopy (cryo-EM) data define the overall envelope of the assembly and rigid-body orientation of the subunits while solid-state nuclear magnetic resonance (ssNMR) chemical shifts and distance constraints define the local secondary structure, protein fold and inter-subunit interactions. Finally, Rosetta structure calculations provide a general framework to integrate the different sources of structural information. Combining a 7.7-Å cryo-EM density map and 996 ssNMR distance constraints, the structure of the type-III secretion system needle of Shigella flexneri is determined to a precision of 0.4?Å. The calculated structures are cross-validated using an independent data set of 691 ssNMR constraints and scanning transmission electron microscopy measurements. The hybrid model resolves the conformation of the non-conserved N terminus, which occupies a protrusion in the cryo-EM density, and reveals conserved pore residues forming a continuous pattern of electrostatic interactions, thereby suggesting a mechanism for effector protein translocation. PMID:25264107

Demers, Jean-Philippe; Habenstein, Birgit; Loquet, Antoine; Kumar Vasa, Suresh; Giller, Karin; Becker, Stefan; Baker, David; Lange, Adam; Sgourakis, Nikolaos G

2014-01-01

222

High-resolution structure of the Shigella type-III secretion needle by solid-state NMR and cryo-electron microscopy  

NASA Astrophysics Data System (ADS)

We introduce a general hybrid approach for determining the structures of supramolecular assemblies. Cryo-electron microscopy (cryo-EM) data define the overall envelope of the assembly and rigid-body orientation of the subunits while solid-state nuclear magnetic resonance (ssNMR) chemical shifts and distance constraints define the local secondary structure, protein fold and inter-subunit interactions. Finally, Rosetta structure calculations provide a general framework to integrate the different sources of structural information. Combining a 7.7-Å cryo-EM density map and 996 ssNMR distance constraints, the structure of the type-III secretion system needle of Shigella flexneri is determined to a precision of 0.4?Å. The calculated structures are cross-validated using an independent data set of 691 ssNMR constraints and scanning transmission electron microscopy measurements. The hybrid model resolves the conformation of the non-conserved N terminus, which occupies a protrusion in the cryo-EM density, and reveals conserved pore residues forming a continuous pattern of electrostatic interactions, thereby suggesting a mechanism for effector protein translocation.

Demers, Jean-Philippe; Habenstein, Birgit; Loquet, Antoine; Kumar Vasa, Suresh; Giller, Karin; Becker, Stefan; Baker, David; Lange, Adam; Sgourakis, Nikolaos G.

2014-09-01

223

Multifunctional superparamagnetic nanoshells: combining two-photon luminescence imaging, surface-enhanced Raman scattering and magnetic separation.  

PubMed

With the increasing need for multi-purpose analysis in the biomedical field, traditional single diagnosis methods cannot meet the requirements. Therefore new multifunctional technologies and materials for the integration of sample collection, sensing and imaging are in great demand. Core-shell nanoparticles offer a unique platform to combine multifunctions in a single particle. In this work, we have constructed a novel type of core-shell superparamagnetic nanoshell (Fe?O?@SiO?@Au), composed of a Fe?O? cluster core, a thin Au shell and a SiO? layer in between. The obtained multifunctional nanoparticles combine the magnetic properties and plasmonic optical properties effectively, which were well investigated by a number of experimental characterization methods and theoretical simulations. We have demonstrated that Fe?O?@SiO?@Au nanoparticles can be utilized for two-photon luminescence (TPL) imaging, near-infrared surface-enhanced Raman scattering (NIR SERS) and cell collection by magnetic separation. The TPL intensity could be further greatly enhanced through the plasmon coupling effect in the self-assembled nanoparticle chains, which were triggered by an external magnetic field. In addition, Fe?O?@SiO?@Au nanoparticles may have great potential applications such as enhanced magnetic resonance imaging (MRI) and photo-thermotherapy. Successful combination of multifunctions including magnetic response, biosensing and bioimaging in single nanoparticles allows further manipulation, real-time tracking, and intracellular molecule analysis of live cells at a single-cell level. PMID:25329447

Jin, Xiulong; Li, Haiyan; Wang, Shanshan; Kong, Ni; Xu, Hong; Fu, Qihua; Gu, Hongchen; Ye, Jian

2014-11-01

224

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

225

Methyl parathion imprinted polymer nanoshell coated on the magnetic nanocore for selective recognition and fast adsorption and separation in soils.  

PubMed

Core-shell magnetic methyl parathion (MP) imprinted polymers (Fe3O4@MPIPs) were fabricated by a layer-by-layer self-assembly process. In order to take full advantage of the synergistic effect of hydrogen-binding interactions and ?-? accumulation between host and guest for molecular recognition, methacrylic acid and 4-vinyl pyridine were chosen as co-functional monomers and their optimal proportion were investigated. The core-shell and crystalline structure, morphology and magnetic properties of Fe3O4@MPIPs were characterized. The MP-imprinted nanoshell was almost uniform and about 100nm thick. Binding experiments demonstrated that Fe3O4@MPIPs possessed excellent binding properties, including high adsorption capacity and specific recognition, as well as fast adsorption kinetics and a fast phase separation rate. The equilibration adsorption capacity reached up to 9.1mg/g, which was 12 times higher than that of magnetic non-imprinted polymers, while adsorption reached equilibrium within 5min at a concentration of 0.2mmol/L. Furthermore, Fe3O4@MPIPs successfully provided selective separation and removal of MP in soils with a recovery and detection limit of 81.1-87.0% and 5.2ng/g, respectively. PMID:24275470

Xu, Shiying; Guo, Changjuan; Li, Yongxian; Yu, Zerong; Wei, Chaohai; Tang, Youwen

2014-01-15

226

Easy-separable magnetic nanoparticle-supported Pd catalysts: Kinetics, stability and catalyst re-use  

Microsoft Academic Search

A series of novel palladium-based catalysts supported on magnetic nanoparticles with diameters of 7–17nm have been prepared and evaluated in C–C coupling, hydrogenation and amination reactions. One type of catalyst used palladium complexes containing phosphine and\\/or acetate ligands for applications in Suzuki and Heck reactions. The second type consisted of Pd(0)-functionalised magnetic cores for use in hydrogenation and C–C coupling.

Urszula Laska; Christopher G. Frost; Gareth J. Price; Pawel K. Plucinski

2009-01-01

227

Eddy current and total power loss separation in the iron–phosphate–polyepoxy soft magnetic composites  

Microsoft Academic Search

This work investigates the magnetic properties of iron–phosphate–polyepoxy soft magnetic composite materials. FTIR spectra, EDX analysis, distribution maps, X-ray diffraction pattern and density measurements show that the particles surface layer contains a thin layer of nanocrystalline\\/amorphous phosphate with high coverage of powders surface. In this paper, a formula for calculating the eddy current loss and total loss components by loss

A. H. Taghvaei; H. Shokrollahi; K. Janghorban; H. Abiri

2009-01-01

228

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

PubMed Central

During herpes simplex virus 1 (HSV1) egress in neurons, viral particles travel from the neuronal cell body along the axon towards the synapse. Whether HSV1 particles are transported as enveloped virions as proposed by the ‘married’ model or as non-enveloped capsids suggested by the ‘separate’ model is controversial. Specific viral proteins may form a recruitment platform for microtubule motors that catalyze such transport. However, their subviral location has remained elusive. Here we established a system to analyze herpesvirus egress by cryo electron tomography. At 16 h post infection, we observed intra-axonal transport of progeny HSV1 viral particles in dissociated hippocampal neurons by live-cell fluorescence microscopy. Cryo electron tomography of frozen-hydrated neurons revealed that most egressing capsids were transported independently of the viral envelope. Unexpectedly, we found not only DNA-containing capsids (cytosolic C-capsids), but also capsids lacking DNA (cytosolic A-/B-capsids) in mid-axon regions. Subvolume averaging revealed lower amounts of tegument on cytosolic A-/B-capsids than on C-capsids. Nevertheless, all capsid types underwent active axonal transport. Therefore, even few tegument proteins on the capsid vertices seemed to suffice for transport. Secondary envelopment of capsids was observed at axon terminals. On their luminal face, the enveloping vesicles were studded with typical glycoprotein-like spikes. Furthermore, we noted an accretion of tegument density at the concave cytosolic face of the vesicle membrane in close proximity to the capsids. Three-dimensional analysis revealed that these assembly sites lacked cytoskeletal elements, but that filamentous actin surrounded them and formed an assembly compartment. Our data support the ‘separate model’ for HSV1 egress, i.e. progeny herpes viruses being transported along axons as subassemblies and not as complete virions within transport vesicles. PMID:22194682

Ibiricu, Iosune; Huiskonen, Juha T.; Döhner, Katinka; Bradke, Frank; Sodeik, Beate; Grünewald, Kay

2011-01-01

229

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. PMID:3755397

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

1986-01-01

230

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

SciTech Connect

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

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

2004-08-02

231

Covariance Matrix Estimation for the Cryo-EM Heterogeneity Problem*  

PubMed Central

In cryo-electron microscopy (cryo-EM), a microscope generates a top view of a sample of randomly oriented copies of a molecule. The problem of single particle reconstruction (SPR) from cryo-EM is to use the resulting set of noisy two-dimensional projection images taken at unknown directions to reconstruct the three-dimensional (3D) structure of the molecule. In some situations, the molecule under examination exhibits structural variability, which poses a fundamental challenge in SPR. The heterogeneity problem is the task of mapping the space of conformational states of a molecule. It has been previously suggested that the leading eigenvectors of the covariance matrix of the 3D molecules can be used to solve the heterogeneity problem. Estimating the covariance matrix is challenging, since only projections of the molecules are observed, but not the molecules themselves. In this paper, we formulate a general problem of covariance estimation from noisy projections of samples. This problem has intimate connections with matrix completion problems and high-dimensional principal component analysis. We propose an estimator and prove its consistency. When there are finitely many heterogeneity classes, the spectrum of the estimated covariance matrix reveals the number of classes. The estimator can be found as the solution to a certain linear system. In the cryo-EM case, the linear operator to be inverted, which we term the projection covariance transform, is an important object in covariance estimation for tomographic problems involving structural variation. Inverting it involves applying a filter akin to the ramp filter in tomography. We design a basis in which this linear operator is sparse and thus can be tractably inverted despite its large size. We demonstrate via numerical experiments on synthetic datasets the robustness of our algorithm to high levels of noise.

Katsevich, E.; Katsevich, A.; Singer, A.

2015-01-01

232

Cryo-balloon catheter position planning using AFiT  

NASA Astrophysics Data System (ADS)

Atrial fibrillation (AFib) is the most common heart arrhythmia. In certain situations, it can result in life-threatening complications such as stroke and heart failure. For paroxsysmal AFib, pulmonary vein isolation (PVI) by catheter ablation is the recommended choice of treatment if drug therapy fails. During minimally invasive procedures, electrically active tissue around the pulmonary veins is destroyed by either applying heat or cryothermal energy to the tissue. The procedure is usually performed in electrophysiology labs under fluoroscopic guidance. Besides radio-frequency catheter ablation devices, so-called single-shot devices, e.g., the cryothermal balloon catheters, are receiving more and more interest in the electrophysiology (EP) community. Single-shot devices may be advantageous for certain cases, since they can simplify the creation of contiguous (gapless) lesion sets around the pulmonary vein which is needed to achieve PVI. In many cases, a 3-D (CT, MRI, or C-arm CT) image of a patient's left atrium is available. This data can then be used for planning purposes and for supporting catheter navigation during the procedure. Cryo-thermal balloon catheters are commercially available in two different sizes. We propose the Atrial Fibrillation Planning Tool (AFiT), which visualizes the segmented left atrium as well as multiple cryo-balloon catheters within a virtual reality, to find out how well cryo-balloons fit to the anatomy of a patient's left atrium. First evaluations have shown that AFiT helps physicians in two ways. First, they can better assess whether cryoballoon ablation or RF ablation is the treatment of choice at all. Second, they can select the proper-size cryo-balloon catheter with more confidence.

Kleinoeder, Andreas; Brost, Alexander; Bourier, Felix; Koch, Martin; Kurzidim, Klaus; Hornegger, Joachim; Strobel, Norbert

2012-02-01

233

Superconductivity, metastability and magnetic field induced phase separation in the atomic limit of the Penson-Kolb-Hubbard model  

E-print Network

We present the analysis of paramagnetic effects of magnetic field ($B$) (Zeeman term) in the zero-bandwidth limit of the extended Hubbard model for arbitrary chemical potential $\\mu$ and electron density $n$. The effective Hamiltonian considered consists of the on-site interaction $U$ and the intersite charge exchange term $I$, determining the hopping of electron pairs between nearest-neighbour sites. The model has been analyzed within the variational approach, which treats the on-site interaction term exactly and the intersite interactions within the mean-field approximation (rigorous in the limit of infinite dimensions $d\\rightarrow+\\infty$). In this report we focus on metastable phases as well as phase separated (PS) states involving superconducting (SS) and nonordered (NO) phases and determine their ranges of occurrence for $U/I_0=1.05$ ($I_0=zI$) in the presence of magnetic field $B\

Kapcia, Konrad Jerzy

2014-01-01

234

Superconductive Magnetic Energy Storage (SMES) System Studies for Electrical Utility at Wisconsin  

E-print Network

," Proc. Ninth Int. Cryo. Eng. Conf., Kobe, 1982, pp. 731 744. 8. Eyssa, Y.M. et al., "Axially Rippled Two-Layer Solenoid for Superconductive Magnetic Energy Storage," Proceedings of the 9th International Conference on Magnet Technology, Zurich...

Boom, R. W.; Eyssa, Y. M.; Abdelsalem, M. K.; Huang, X.

235

Dependence of magnetic field sensitivity of a magnetoelectric laminate sensor pair on separation distance: Effect of mutual inductance  

NASA Astrophysics Data System (ADS)

The effect of mutual inductance on the performance of a pair of Metglas/Pb(Zr,Ti)O3 laminate magnetoelectric (ME) sensors has been studied. The effective value of the ME coefficient (?ME) for the laminates was reduced when the distance between was < 40 mm. Separating the two laminates by distances of > 40 mm, the effect of mutual inductance was small. The laminates exhibited the maximum values of ?ME. The ME sensor unit with two laminates connected in parallel had higher magnetic field sensitivities.

Li, Menghui; Wang, Yaojin; Gao, Junqi; Gray, David; Li, Jiefang; Viehland, D.

2012-02-01

236

Vapor-liquid phase separator studies  

SciTech Connect

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.

1983-10-01

237

Self-assembled monolayers improve protein distribution on holey carbon cryo-EM supports  

PubMed Central

Poor partitioning of macromolecules into the holes of holey carbon support grids frequently limits structural determination by single particle cryo-electron microscopy (cryo-EM). Here, we present a method to deposit, on gold-coated carbon grids, a self-assembled monolayer whose surface properties can be controlled by chemical modification. We demonstrate the utility of this approach to drive partitioning of ionotropic glutamate receptors into the holes, thereby enabling 3D structural analysis using cryo-EM methods. PMID:25403871

Meyerson, Joel R.; Rao, Prashant; Kumar, Janesh; Chittori, Sagar; Banerjee, Soojay; Pierson, Jason; Mayer, Mark L.; Subramaniam, Sriram

2014-01-01

238

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

EPA Science Inventory

The performance of magnetically separable N-doped TiO2 was found to be significantly improved when compared with a non-magnetic N-doped TiO2 for the aqueous removal of cyanotoxin Microcystin-LR. The observed enhanced photocatalytic activity may be related to the presence of ferri...

239

Cocaine detection via rolling circle amplification of short DNA strand separated by magnetic beads  

Microsoft Academic Search

A novel and sensitive fluorescence biosensor based on aptamer and rolling circle amplification for the determination of cocaine was developed in the present work. Here cocaine aptamers immobilized onto Au nanoparticles modified magnetic beads hybridized with short DNA strand. In the presence of cocaine, the short DNA strand was displaced from aptamer owing to cocaine specially binding with aptamer. Next,

Cuiping Ma; Wenshuo Wang; Qing Yang; Chao Shi; Lijie Cao

2011-01-01

240

Studies in matter antimatter separation and in the origin of lunar magnetism  

NASA Technical Reports Server (NTRS)

A progress report, covering lunar and planetary research is introduced. Data cover lunar ionospheric models, lunar and planetary geology, and lunar magnetism. Wind tunnel simulations of Mars aeolian problems and a comparative study of basaltic analogs of Lunar and Martial volcanic features was discussed.

Barker, W. A.; Greeley, R.; Parkin, C.; Aggarwal, H.; Schultz, P.

1975-01-01

241

Magnetic and highly recyclable macroporous carbon nanotubes for spilled oil sorption and separation.  

PubMed

Development of sorbent materials with high selectivity and sorption capacity, easy collection and recyclability is demanding for spilled oil recovery. Although many sorption materials have been proposed, a systematic study on how they can be reused and possible performance degradation during regeneration remains absent. Here we report magnetic carbon nanotube sponges (Me-CNT sponge), which are porous structures consisting of interconnected CNTs with rich Fe encapsulation. The Me-CNT sponges show high mass sorption capacity for diesel oil reached 56 g/g, corresponding to a volume sorption capacity of 99%. The sponges are mechanically strong and oil can be squeezed out by compression. They can be recycled using through reclamation by magnetic force and desorption by simple heat treatment. The Me-CNT sponges maintain original structure, high capacity, and selectivity after 1000 sorption and reclamation cycles. Our results suggest that practical application of CNT macrostructures in the field of spilled oil recovery is feasible. PMID:23721652

Gui, Xuchun; Zeng, Zhiping; Lin, Zhiqiang; Gan, Qiming; Xiang, Rong; Zhu, Yuan; Cao, Anyuan; Tang, Zikang

2013-06-26

242

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

243

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

244

CALCULATING SEPARATE MAGNETIC FREE ENERGY ESTIMATES FOR ACTIVE REGIONS PRODUCING MULTIPLE FLARES: NOAA AR11158  

SciTech Connect

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 A 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 Multiplication-Sign 10{sup 20} Mx, 2.0 Multiplication-Sign 10{sup 20} Mx, and 21.0 Multiplication-Sign 10{sup 20} Mx, respectively, resulting in free energy drops of 3.89 Multiplication-Sign 10{sup 30} erg, 2.62 Multiplication-Sign 10{sup 30} erg, and 1.68 Multiplication-Sign 10{sup 32} erg.

Tarr, Lucas; Longcope, Dana; Millhouse, Margaret [Department of Physics, Montana State University, Bozeman, MT 59717 (United States)

2013-06-10

245

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

E-print Network

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 \\emph{Helioseismic and Magnetic Imager} (HMI) onboard the \\emph{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, 2 M--class, and the X2.2 Valentine's Day Flare during the four days after initial emergence on February 12th, 2011. 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\\AA\\ chann...

Tarr, Lucas A; Millhouse, Margaret

2013-01-01

246

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. PMID:22579361

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

2012-01-01

247

Interim cryo-cooler/detector report  

SciTech Connect

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

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

1995-04-19

248

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

249

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

SciTech Connect

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. [GSI Helmholtzzentrum für Schwerionenforschung GmbH, 64291 Darmstadt (Germany)

2014-01-29

250

Enantioselective separation of chiral aromatic amino acids with surface functionalized magnetic nanoparticles.  

PubMed

Chiral resolution aromatic amino acids, DL-tryptophan (DL-Trp), DL-phenylalanine (DL-Phe), DL-tyrosine (DL-Tyr) from phosphate buffer solution was achieved in present study employing the concept of selective adsorption by surface functionalized magnetic nanoparticles (MNPs). Surfaces of magnetic nanoparticles were functionalized with silica and carboxymethyl-?-cyclodextrin (CMCD) to investigate their adsorption resolution characteristics. Resolution of enantiomers from racemic mixture was quantified in terms of enantiomeric excess using chromatographic method. The MNPs selectively adsorbed L-enantiomers of DL-Trp, DL-Phe, and DL-Tyr from racemic mixture and enantiomeric excesses (e.e.) were determined as 94%, 73% and 58%, respectively. FTIR studies demonstrated that hydrophobic portion of enantiomer penetrated into hydrophobic cavity of cyclodextrin molecules to form inclusion complex. Furthermore, adsorption site was explored using XPS and it was revealed that amino group at chiral center of the amino acid molecule formed hydrogen bond with secondary hydroxyl group of CMCD molecule and favorability of hydrogen bond formation resulted in selective adsorption of L-enantiomer. Finally, stability constant (K) and Gibbs free energy change (-?G°) for inclusion complexation of CMCD with L-/D-enantiomers of amino acids were determined using spectroflurometry in aqueous buffer solution. Higher binding constants were obtained for inclusion complexation of CMCD with L-enantiomers compared to D-enantiomers which stimulated enantioselective properties of CMCD functionalized magnetite silica nanoparticles. PMID:23384689

Ghosh, Sudipa; Fang, Tan Hui; Uddin, M S; Hidajat, K

2013-05-01

251

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

252

Capturing enveloped viruses on affinity grids for downstream cryo-electron microscopy applications  

Technology Transfer Automated Retrieval System (TEKTRAN)

Electron microscopy cryo-electron microscopy and cryo-electron tomography are essential techniques used for characterizing basic virus morphology and determining the three-dimensional structure of viruses. Enveloped viruses, which contain an outer lipoprotein coat, constitute the largest group of pa...

253

REPRESENTATION THEORETIC PATTERNS IN THREE DIMENSIONAL CRYO-ELECTRON MICROSCOPY III -  

E-print Network

REPRESENTATION THEORETIC PATTERNS IN THREE DIMENSIONAL CRYO-ELECTRON MICROSCOPY III - PRESENCE-dimensional structure determination of large biological molecules from cryo-electron microscopy pro- jection images of many important molecules such as various complex of proteins and exterior shells of viruses. Symmetric

Gurevich, Shamgar

254

REPRESENTATION THEORETIC PATTERNS IN THREE DIMENSIONAL CRYO-ELECTRON MICROSCOPY III -  

E-print Network

REPRESENTATION THEORETIC PATTERNS IN THREE DIMENSIONAL CRYO-ELECTRON MICROSCOPY III - PRESENCE-dimensional structure deter- mination of large biological molecules from cryo-electron microscopy projection images and exterior shells of viruses. Symmetric biological molecules, usually appear as complexes, composed

Gurevich, Shamgar

255

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. PMID:24262358

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

2014-01-01

256

Heparin binding sites on Ross River virus revealed by electron cryo-microscopy  

E-print Network

Heparin binding sites on Ross River virus revealed by electron cryo-microscopy Wei Zhang, Marintha complex with heparin were determined through the use of electron cryo-microscopy and image reconstruction methods. Heparin was found to bind at the distal end of the RRV spikes, in a region of the E2 glycoprotein

Baker, Timothy S.

257

Bio-inspired cryo-ink preserves red blood cell phenotype and function during nanoliter vitrification.  

PubMed

Current red-blood-cell cryopreservation methods utilize bulk volumes, causing cryo-injury of cells, which results in irreversible disruption of cell morphology, mechanics, and function. An innovative approach to preserve human red-blood-cell morphology, mechanics, and function following vitrification in nanoliter volumes is developed using a novel cryo-ink integrated with a bioprinting approach. PMID:25047246

El Assal, Rami; Guven, Sinan; Gurkan, Umut Atakan; Gozen, Irep; Shafiee, Hadi; Dalbeyler, Sedef; Abdalla, Noor; Thomas, Gawain; Fuld, Wendy; Illigens, Ben M W; Estanislau, Jessica; Khoory, Joseph; Kaufman, Richard; Zylberberg, Claudia; Lindeman, Neal; Wen, Qi; Ghiran, Ionita; Demirci, Utkan

2014-09-01

258

Towards an atlas of mammalian cell ultrastructure by cryo soft X-ray tomography  

PubMed Central

We provide a catalog of 3D cryo soft X-ray tomography (cryo-SXT) images obtained from ~6–12 µm thick mouse adenocarcinoma cells. Included are multiple representative images of nuclei, nucleoli, nuclear membrane, nuclear membrane channels, mitochondria, lysosomes, endoplasmic reticulum, filaments and plasma membrane, plus three structures not previously described by cryo-SXT, namely Golgi, microvilli and nuclear-membrane blebs. Sections from the 3D cryo-SXT tomograms for all the preceding structures closely resemble those seen by thin-section transmission electron microscopy (TEM). Some structures such as nuclear-membrane channels and nuclear-membrane blebs are more easily detected by cryo-SXT than TEM most likely due to their better contrast and cellular preservation in cryo-SXT combined with the ability to rapidly locate these structures within a full 3D image. We identify and discuss two current limitations in cryo-SXT: variability in image quality and difficulties in detecting weaker contrast structures such as chromatin and various nuclear bodies. Progress on these points is likely to come from the solution of several technical problems in image acquisition, plus the implementation of advanced cryo soft X-ray microscopy approaches such as phase contrast or optical sectioning. PMID:22155291

Müller, Waltraud G.; Heymann, J. Bernard; Nagashima, Kunio; Guttmann, Peter; Werner, Stephan; Rehbein, Stefan; Schneider, Gerd; McNally, James G.

2011-01-01

259

Cryo-electron tomography of microtubule-kinesin motor complexes  

PubMed Central

Microtubules complexed with molecular motors of the kinesin family or non-motor microtubule associated proteins (MAPs) such as tau or EB1 have been the subject of cryo-electron microcopy based 3-D studies for several years. Most of these studies that targeted complexes with intact microtubules have been carried out by helical 3-D reconstruction, while few were analyzed by single particle approaches or from 2-D crystalline arrays. Helical reconstruction of microtubule-MAP or motor complexes has been extremely successful but by definition, all helical 3-D reconstruction attempts require perfectly helical assemblies, which present a serious limitation and confine the attempts to 15- or 16-protofilament microtubules, microtubule configurations that are very rare in nature. The rise of cryo-electron tomography within the last few years has now opened a new avenue towards solving 3-D structures of microtubule-MAP complexes that do not form helical assemblies, most importantly for the subject here, all microtubules that exhibit a lattice seam. In addition, not all motor domains or MAPs decorate the microtubule surface regularly enough to match the underlying microtubule lattice, or they adopt conformations that deviate from helical symmetry. Here we demonstrate the power and limitation of cryo-electron tomography using two kinesin motor domains, the monomeric Eg5 motor domain, and the heterodimeric Kar3Vik1 motor. We show here that tomography does not exclude the possibility of post-tomographic averaging when identical subvolumes can be extracted from tomograms and in both cases we were able to reconstruct 3-D maps of conformations that are not possible to obtain using helical or other averaging-based methods. PMID:20025975

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

2010-01-01

260

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

261

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

SciTech Connect

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

Yashita, S.

1984-02-01

262

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

SciTech Connect

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

Yashita, S.

1983-01-01

263

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

E-print Network

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.

G. S. Bali; F. Bruckmann; G. Endrodi; Z. Fodor; S. D. Katz; A. Schafer

2014-03-31

264

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

265

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

SciTech Connect

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

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

2008-09-07

266

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

SciTech Connect

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

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

2008-01-01

267

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

268

Utility of Temporally-Extended Signal Space Separation Algorithm for Magnetic Noise from Vagal Nerve Stimulators  

PubMed Central

Object To evaluate the utility of a temporally-extended Signal Space Separation algorithm (tSSS) for patients with vagal nerve stimulator (VNS) Methods We evaluated median nerve somatosensory evoked responses (SER) of magnetoencephalography (MEG) in 27 VNS patients (48 sides) with/without tSSS processing. We classified SER dipoles as ‘acceptable’ if: A) the location of the dipole was in the expected location in the central sulcus, and B) the Goodness Of Fit value (GOF) was greater than 80%. We evaluated 1) the number of sides which produced acceptable dipoles in each dataset (i.e. with/without tSSS processing), and in cases where the both data produced reliable dipoles, 2) compared their GOFs and the 95% Confidence Volumes (CV) (mm3). Statistical differences in the GOF and CV between with/without tSSS conditions were determined by paired t test. Results Only 11 (23%) responses had reliable dipoles without tSSS processing, while all 48 (100%) had acceptable dipoles under tSSS processing. Additionally, the latter group had significantly higher GOF (increased by 7% on average) and lower CV (mean decrease of 200 mm3) than the former (p < 0.01). Conclusion Processing with tSSS quantitatively improves dipole fitting of known sources in VNS patients. Significance This algorithm permits satisfactory MEG testing in the relatively commonly encountered epilepsy patient with VNS. PMID:22727713

Kakisaka, Yosuke; Mosher, John C.; Wang, Zhong I.; Jin, Kazutaka; Dubarry, Anne-Sophie; Alexopoulos, Andreas V.; Burgess, Richard C.

2014-01-01

269

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

270

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

271

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

272

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

273

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. PMID:21852942

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

274

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

EPA Science Inventory

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

275

Proceedings of the 22nd sensor symposium, Oct. 20-21, 2005, Tokyo, pp 125 -128 Micro Magnetic Separator for Stem Cell Sorting System  

E-print Network

Separator for Stem Cell Sorting System Hiromichi Inokuchi Yuji Suzuki Nobuhide Kasagi Naoki Shikazono sorting (uIMCS) system for ex- tracting stem cells from peripheral blood. In this report, micro magnetic, in which pluripotent stem cells extracted from a patient's body are cultured to differen- tiate

Kasagi, Nobuhide

276

Capturing RNA-dependent pathways for cryo-EM analysis  

PubMed Central

Cryo-Electron Microscopy (EM) is a powerful technique to visualize biological processes at nanometer resolution. Structural studies of macromolecular assemblies are typically performed on individual complexes that are biochemically isolated from their cellular context. Here we present a molecular imaging platform to capture and view multiple components of cellular pathways within a functionally relevant framework. We utilized the bacterial protein synthesis machinery as a model system to develop our approach. By using modified Affinity Grid surfaces, we were able to recruit multiple protein assemblies bound to nascent strands of mRNA. The combined use of Affinity Capture technology and single particle electron microscopy provide the basis for visualizing RNA-dependent pathways in a remarkable new way. PMID:24688633

Tanner, Justin R.; Degen, Katherine; Gilmore, Brian L.; Kelly, Deborah F.

2012-01-01

277

High Resolution CryoFESEM of Microbial Surfaces  

NASA Astrophysics Data System (ADS)

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

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

2003-08-01

278

G-Quadruplex-based DNAzyme for colorimetric detection of cocaine: using magnetic nanoparticles as the separation and amplification element.  

PubMed

The appearance of the aptamer provides good recognition elements for small molecules, especially for drugs. In this work, by combining the advantages of magnetic nanoparticles (MNPs) with colorimetric drug detection using hemin-G-quadruplex complex as the sensing element, we report a simple and sensitive DNAzyme-based colorimetric sensor for cocaine detection in a 3,3,5,5-tetramethylbenzidine sulfate (TMB)-H(2)O(2) reaction system. The whole experimental processes are simplified. Cocaine aptamer fragments, SH-C2, are covalently labeled onto the amine-functionalized MNPs. When the target cocaine and another cocaine aptamer fragments (C1) grafted with G-riched strand AG4 (i.e. C1-AG4) are present simultaneously, the C2 layer on MNPs hybridizes partly with C1-AG4 to bind the cocaine. The C1-AG4 can be combinded with hemin to form DNAzyme which can effectively catalyze the H(2)O(2)-mediated oxidation of TMB, giving rise to a change in solution color. Importantly, using MNPs as the separation and amplification elements could effectively reduce the background signal and the interference from the real samples. A linear response from 0.1 ?M to 20 ?M is obtained for cocaine and a detection limit of 50 nM is achieved, which provides high sensitivity and selectivity to detect cocaine. PMID:21079882

Du, Yan; Li, Bingling; Guo, Shaojun; Zhou, Zhixue; Zhou, Ming; Wang, Erkang; Dong, Shaojun

2011-02-01

279

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

PubMed Central

SUMMARY Zernike phase contrast cryo-electron microscopy (ZPC-cryoEM) is an emerging technique which is capable of producing higher image contrast than conventional cryoEM. By combining this technique with advanced image processing methods, we achieved subnanometer resolution for two biological specimens: 2-D bacteriorhodopsin crystal and epsilon15 bacteriophage. For an asymmetric reconstruction of epsilon15 bacteriophage, ZPC-cryoEM can reduce the required amount of data by a factor of ~3 compared to conventional cryoEM. The reconstruction was carried out to 13 Å resolution without the need to correct the contrast transfer function. New structural features at the portal vertex of the epsilon15 bacteriophage are revealed in this reconstruction. Using ZPC cryo-electron tomography (ZPC-cryoET), a similar level of data reduction and higher resolution structures of epsilon15 bacteriophage can be obtained relative to conventional cryoET. These results show quantitatively the benefits of ZPC-cryoEM and -cryoET for structural determinations of macromolecular machines at nanometer and subnanometer resolutions. PMID:20696391

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

2010-01-01

280

Cryo-EM of macromolecular assemblies at near-atomic resolution.  

PubMed

With single-particle electron cryomicroscopy (cryo-EM), it is possible to visualize large, macromolecular assemblies in near-native states. Although subnanometer resolutions have been routinely achieved for many specimens, state of the art cryo-EM has pushed to near-atomic (3.3-4.6 Å) resolutions. At these resolutions, it is now possible to construct reliable atomic models directly from the cryo-EM density map. In this study, we describe our recently developed protocols for performing the three-dimensional reconstruction and modeling of Mm-cpn, a group II chaperonin, determined to 4.3 Å resolution. This protocol, utilizing the software tools EMAN, Gorgon and Coot, can be adapted for use with nearly all specimens imaged with cryo-EM that target beyond 5 Å resolution. Additionally, the feature recognition and computational modeling tools can be applied to any near-atomic resolution density maps, including those from X-ray crystallography. PMID:20885381

Baker, Matthew L; Zhang, Junjie; Ludtke, Steven J; Chiu, Wah

2010-09-01

281

Segmentation and registration of molecular components in 3-dimensional density maps from cryo-electron microscopy  

E-print Network

Cryo-electron microscopy is a method that produces 3D density maps of macromolecular complexes. Segmentation and registration methods are heavily used to extract structural information from such density maps. Segmentation ...

Pintilie, Grigore Dimitrie, 1976-

2010-01-01

282

Step by step manipulation of the CryoCapsule with HPM high pressure freezers.  

PubMed

The CryoCapsule is a tool dedicated to correlative light to electron microscopy experiments. Focused on simplifying the specimen manipulation throughout the entire workflow from live-cell imaging to freeze substitution following cryofixation by high pressure freezing, we introduce here a step by step procedure to use the CryoCapsule either with the high pressure freezing machines: HPM010 or the HPM100. PMID:25287845

Heiligenstein, Xavier; Hurbain, Ilse; Delevoye, Cédric; Salamero, Jean; Antony, Claude; Raposo, Graca

2014-01-01

283

Impact of CryoSat-2 for marine gravity field - globally and in the Arctic Ocean  

NASA Astrophysics Data System (ADS)

CryoSat-2 offers at least four important improvements compared with conventional altimetry which should benefit marine gravity in general but particularly at high latitude. Firstly the ESA CryoSat-2 signal to noise ratio should be a factor of two better than conventional altimetry. Secondly the 369 days repeat offered by CryoSat-2 provides denser coverage than older geodetic mission data set like ERS-1. Thirdly, the 92 degree inclination of CryoSat-2 is designed to map more of the Arctic Ocean than previous altimetric satellites. Finally, CryoSat-2 is able to operate in two new modes (SAR and SAR-in) designed to improve the sea surface /ice height mapping in the Polar Regions. We have investigated the use of two years of CryoSat-2 LRM data as well as CryoSat SAR and SAR-in data for deriving a global gravity field as well as a regional marine gravity field in the Arctic. Both conventional ESA Level 2 GDR data, NOAA LRM data, but also Level1b (LRM, SAR and SAR-in waveforms) data have been analyzed. A suite of eight different empirical retrackers have been developed and investigated for their ability to predict marine gravity in the Arctic Ocean. The impact of the various improvement offered by CryoSat-2 in comparison with conventional satellite altimetry have been studied and quantified both globally but particularly for the Arctic Ocean using a large number of marine and airborne surveys providing "ground truth" marine gravity.

Andersen, O. B.; Stenseng, L.; Knudsen, P.; Jain, M.

2012-12-01

284

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

285

Direct observation of liquid crystals using cryo-TEM: specimen preparation and low-dose imaging.  

PubMed

Liquid crystals (LCs) represent a challenging group of materials for direct transmission electron microscopy (TEM) studies due to the complications in specimen preparation and the severe radiation damage. In this paper, we summarize a series of specimen preparation methods, including thin film and cryo-sectioning approaches, as a comprehensive toolset enabling high-resolution direct cryo-TEM observation of a broad range of LCs. We also present comparative analysis using cryo-TEM and replica freeze-fracture TEM on both thermotropic and lyotropic LCs. In addition to the revisits of previous practices, some new concepts are introduced, e.g., suspended thermotropic LC thin films, combined high-pressure freezing and cryo-sectioning of lyotropic LCs, and the complementary applications of direct TEM and indirect replica TEM techniques. The significance of subnanometer resolution cryo-TEM observation is demonstrated in a few important issues in LC studies, including providing direct evidences for the existence of nanoscale smectic domains in nematic bent-core thermotropic LCs, comprehensive understanding of the twist-bend nematic phase, and probing the packing of columnar aggregates in lyotropic chromonic LCs. Direct TEM observation opens ways to a variety of TEM techniques, suggesting that TEM (replica, cryo, and in situ techniques), in general, may be a promising part of the solution to the lack of effective structural probe at the molecular scale in LC studies. PMID:25045045

Gao, Min; Kim, Young-Ki; Zhang, Cuiyu; Borshch, Volodymyr; Zhou, Shuang; Park, Heung-Shik; Jákli, Antal; Lavrentovich, Oleg D; Tamba, Maria-Gabriela; Kohlmeier, Alexandra; Mehl, Georg H; Weissflog, Wolfgang; Studer, Daniel; Zuber, Benoît; Gnägi, Helmut; Lin, Fang

2014-10-01

286

Targeted nano analysis of water and ions in the nucleus using cryo-correlative microscopy.  

PubMed

The cell nucleus is a crowded volume in which the concentration of macromolecules is high. These macromolecules sequester most of the water molecules and ions which, together, are very important for stabilization and folding of proteins and nucleic acids. To better understand how the localization and quantity of water and ions vary with nuclear activity, it is necessary to study them simultaneously by using newly developed cell imaging approaches. Some years ago, we showed that dark-field cryo-Scanning Transmission Electron Microscopy (cryo-STEM) allows quantification of the mass percentages of water, dry matter, and elements (among which are ions) in freeze-dried ultrathin sections. To overcome the difficulty of clearly identifying nuclear subcompartments imaged by STEM in ultrathin cryo-sections, we developed a new cryo correlative light and STEM imaging procedure. This combines fluorescence imaging of nuclear GFP-tagged proteins to identify, within cryo ultrathin sections, regions of interest which are then analyzed by STEM for quantification of water and identification and quantification of ions. In this chapter we describe the new setup we have developed to perform this cryo-correlative light and STEM imaging approach, which allows a targeted nano analysis of water and ions in nuclear compartments. PMID:25311128

Nolin, Frédérique; Ploton, Dominique; Wortham, Laurence; Tchelidze, Pavel; Bobichon, Hélène; Banchet, Vincent; Lalun, Nathalie; Terryn, Christine; Michel, Jean

2015-01-01

287

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

288

CryoSat: A mission to determine the fluctuations in Earth’s land and marine ice fields  

Microsoft Academic Search

This paper describes the CryoSat satellite mission, due for launch in 2005, whose aim is to accurately determine the trends in Earth’s continental and marine ice fields. The paper’s purpose is to provide scientific users of the CryoSat data with a description of the design and operation of the SIRAL radar and the CryoSat platform, the data products, and the

D. J. Wingham; C. R. Francis; S. Baker; C. Bouzinac; D. Brockley; R. Cullen; P. de Chateau-Thierry; S. W. Laxon; U. Mallow; C. Mavrocordatos; L. Phalippou; G. Ratier; L. Rey; F. Rostan; P. Viau; D. W. Wallis

2006-01-01

289

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

290

CryoSat collision warning and low thrust avoidance manoeuvre strategy  

NASA Astrophysics Data System (ADS)

As a consequence of the steady growth of space debris, the resulting collision risk between Earth orbiting objects has, in recent years, become a non-negligible factor for launch and on-orbit operations. Most of the Earth orbiting satellite shall have propulsion and operation capabilities to perform collision avoidance manoeuvres and end-of-life de-orbiting. The CryoSat satellite case is here presented. CryoSat is the first of the ESA's Earth Explorer Opportunity Mission spacecraft. The first step in avoiding a collision between two orbiting objects is the detection of potential collision events. In the framework of the CryoSat mission Phase-A/B, one collision event has been predicted for the three and a half years of CryoSat nominal mission lifetime. The optimum avoiding manoeuvre strategy with low thrust has been computed and here described. Given the low thrust available for the CryoSat mission, the avoidance manoeuvre has to be planned and started well in advance of the predicted impact date. An analysis of the required delta-v as a function of the collision manoeuvre starting point and the number of thrust arcs has been performed.

Graziano, Mariella; Pirondini, Fabrizio; Sánchez, Noelia; di Sotto, Emanuele

2001-10-01

291

Structure of ?-galactosidase at 3.2-Å resolution obtained by cryo-electron microscopy  

PubMed Central

We report the solution structure of Escherichia coli ?-galactosidase (?465 kDa), solved at ?3.2-Å resolution by using single-particle cryo-electron microscopy (cryo-EM). Densities for most side chains, including those of residues in the active site, and a catalytic Mg2+ ion can be discerned in the map obtained by cryo-EM. The atomic model derived from our cryo-EM analysis closely matches the 1.7-Å crystal structure with a global rmsd of ?0.66 Å. There are significant local differences throughout the protein, with clear evidence for conformational changes resulting from contact zones in the crystal lattice. Inspection of the map reveals that although densities for residues with positively charged and neutral side chains are well resolved, systematically weaker densities are observed for residues with negatively charged side chains. We show that the weaker densities for negatively charged residues arise from their greater sensitivity to radiation damage from electron irradiation as determined by comparison of density maps obtained by using electron doses ranging from 10 to 30 e?/Å2. In summary, we establish that it is feasible to use cryo-EM to determine near-atomic resolution structures of protein complexes (<500 kDa) with low symmetry, and that the residue-specific radiation damage that occurs with increasing electron dose can be monitored by using dose fractionation tools available with direct electron detector technology. PMID:25071206

Bartesaghi, Alberto; Matthies, Doreen; Banerjee, Soojay; Merk, Alan; Subramaniam, Sriram

2014-01-01

292

Cryo-SEM and subsequent TEM examinations of identical neural tissue specimen.  

PubMed

Low temperature scanning electron microscopy of frozen-fractured specimens under cryo-protecting, non-dehydrating, and non-etching "wet" conditions, that is, direct cryo-SEM, was followed by transmission electron microscopy (TEM) with the same neural tissue specimens. In comparison to replica TEM, direct cryo-SEM can obtain images with a smooth gradation of contrast. The major advantage of direct cryo-SEM combined with TEM was that time was saved in SEM preparation. It had a high potentiality at a wide-range survey of multi-dimensional specimen structures with less-artifacts. Because the specimens were prepared as quickly as possible under "wet" conditions, the target structures could be examined under lower through higher magnifications. In the present study, neuronal and glial elements, such as plasma membranes and cell organelles that include the synaptic vesicles, were localized on the fractured surface. In subsequent TEM examination, it was confirmed that the underlying internal structures could be further characterized from cytological as well as molecular biological aspects. In addition, direct cryo-SEM distinctively demonstrated small intra-membrane particles (ca. 10 nm in diameter). However, due to electron lucency, they could not be confirmed in the re-processed TEM specimens. Applying the present protocol, stereological and internal architectural examinations of the neural tissues have been simultaneously conducted at ultra-fine levels. PMID:15721815

Nakatomi, Reiko; Hayashida, Tsuyako; Fujimoto, Kazushi; Tohyama, Koujiro; Hashikawa, Tsutomu

2005-02-01

293

Quantitative analysis of polymer colloids by cryo-transmission electron microscopy.  

PubMed

The structure of colloidal latex particles in dilute suspension at room temperature is investigated by cryogenic transmission electron microscopy (cryo-TEM). Two types of particles are analyzed: (i) core particles made of polystyrene with a thin layer of poly(N-isopropylacrylamide) (PNIPAM) and (ii) core-shell particles consisting of core particles onto which a network of cross-linked PNIPAM is affixed. Both systems are also studied by small-angle X-ray scattering (SAXS). The radial density profile of both types of particles have been derived from the cryo-TEM micrographs by image processing and compared to the results obtained by SAXS. Full agreement is found for the core particles. There is a discrepancy between the two methods in case of the core-shell particles. The discrepancy is due to the buckling of the network affixed to the surface. The buckling is clearly visible in the cryo-TEM pictures. The overall dimensions derived from cryo-TEM agree well with the hydrodynamic radius of the particles. The comparison of these data with the analysis by SAXS shows that SAXS is only sensitive to the average radial structure as expected. All data show that cryo-TEM micrographs can be evaluated to yield quantitative information about the structure of colloidal particles. PMID:19317419

Crassous, J J; Rochette, C N; Wittemann, A; Schrinner, M; Ballauff, M; Drechsler, M

2009-07-21

294

Structural characterization of amphiphilic homopolymer micelles using light scattering, SANS, and cryo-TEM.  

PubMed

We report the aqueous solution self-assembly of a series of poly(N-isopropylacrylamide) (PNIPAM) polymers end-functionalized with a hydrophobic sulfur-carbon-sulfur (SCS) pincer ligand. Although the hydrophobic ligand accounted for <5 wt% of the overall homopolymer mass, the polymers self-assembled into well-defined spherical micelles in aqueous solution, and these micelles are potential precursors to solution-assembled nanoreactors for small molecule catalysis applications. The micelle structural details were investigated using light scattering, cryogenic transmission electron microscopy (cryo-TEM), and small angle neutron scattering (SANS). Radial density profiles extracted from the cryo-TEM micrographs suggested that the PNIPAM chains formed a diffuse corona with a radially decreasing corona density profile and provided valuable a priori information about the micelle structure for SANS data modeling. SANS analysis indicated a similar profile in which the corona surrounded a small hydrophobic core containing the pincer ligand. The similarity between the SANS and cryo-TEM results demonstrated that detailed information about the micelle density profile can be obtained directly from cryo-TEM and highlighted the complementary use of scattering and cryo-TEM in the structural characterization of solution-assemblies, such as the SCS pincer-functionalized homopolymers described here. PMID:24058209

Patterson, Joseph P; Kelley, Elizabeth G; Murphy, Ryan P; Moughton, Adam O; Robin, Mathew; Lu, Annhelen; Colombani, Olivier; Chassenieux, Christophe; Cheung, David; Sullivan, Millicent O; Epps, Thomas H; O'Reilly, Rachel K

2013-08-13

295

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. PMID:24565374

2013-01-01

296

Electron cryo-tomographic structure of cystovirus {phi}12  

SciTech Connect

Bacteriophage {phi}12 is a member of the Cystoviridae virus family and contains a genome consisting of three segments of double-stranded RNA (dsRNA). This virus family contains eight identified members, of which four have been classified in regard to their complete genomic sequence and encoded viral proteins. A phospholipid envelope that contains the integral proteins P6, P9, P10, and P13 surrounds the viral particles. In species {phi}6, host infection requires binding of a multimeric P3 complex to type IV pili. In species {phi}8, {phi}12, and {phi}13, the attachment apparatus is a heteromeric protein assembly that utilizes the rough lipopolysaccharide (rlps) as a receptor. In {phi}8 the protein components are designated P3a and P3b while in species {phi}12 proteins P3a and P3c have been identified in the complex. The phospholipid envelope of the cystoviruses surrounds a nucleocapsid (NC) composed of two shells. The outer shell is composed of protein P8 with a T = 13 icosahedral lattice while the primary component of the inner shell is a dodecahedral frame composed of dimeric protein P1. For the current study, the 3D architecture of the intact {phi}12 virus was obtained by electron cryo-tomography. The nucleocapsid appears to be centered within the membrane envelope and possibly attached to it by bridging structures. Two types of densities were observed protruding from the membrane envelope. The densities of the first type were elongated, running parallel, and closely associated to the envelope outer surface. In contrast, the second density was positioned about 12 nm above the envelope connected to it by a flexible low-density stem. This second structure formed a torroidal structure termed 'the donut' and appears to inhibit BHT-induced viral envelope fusion.

Hu Guobin [Structural Biology Program, Skirball Institute of Biomolecular Medicine, New York University School of Medicine, New York, NY 10016 (United States); Wei Hui [Department of Microbiology and Immunology, Sophie Davis School of Biomedical Education, City College of New York, NY 10031 (United States); Rice, William J. [New York Structural Biology Center, 89 Convent Avenue, New York, NY 10027 (United States); Stokes, David L. [Structural Biology Program, Skirball Institute of Biomolecular Medicine, New York University School of Medicine, New York, NY 10016 (United States); New York Structural Biology Center, 89 Convent Avenue, New York, NY 10027 (United States); Gottlieb, Paul [Department of Microbiology and Immunology, Sophie Davis School of Biomedical Education, City College of New York, NY 10031 (United States); Ph.D. Program in Biology, Graduate School and University Center, City University of New York, NY 10016 (United States)], E-mail: pgottl@med.cuny.edu

2008-03-01

297

gEMpicker: A Highly Parallel GPU-Accelerated Particle Picking Tool for Cryo-Electron Microscopy  

E-print Network

gEMpicker: A Highly Parallel GPU-Accelerated Particle Picking Tool for Cryo-Electron Microscopy Abstract Background: Picking images of particles in cryo-electron micrographs is an important step particle images. Thus, a computational bottleneck in reaching high resolution is the accurate and automatic

Boyer, Edmond

298

PhD in Cryosphere Geophysics The Cryosphere Geophysics and Remote Sensing group (CryoGARs) at Boise  

E-print Network

PhD in Cryosphere Geophysics The Cryosphere Geophysics and Remote Sensing group (CryoGARs) at Boise on the GrIS. A solid background in field geophysics is preferred. The successful applicant will join the CryoGars group and Center for Geophysical Investigation of the Shallow Subsurface (CGISS) at Boise

Barrash, Warren

299

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

SciTech Connect

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.

Estrozi, L.F.; Neumann, E. [IBS, Institut de Biologie Structurale Jean-Pierre Ebel. CEA, CNRS, Universite Joseph Fourier. 41 rue Jules Horowitz, F-38027 Grenoble (France); Squires, G. [Institut Curie, 26, rue d'Ulm 75248 Paris Cedex 05 (France); Rozas-Dennis, G. [Departamento de Biologia, Bioquimica y Farmacia, U.N.S., San Juan 670, (8000) Bahia Blanca (Argentina); Costabel, M. [Grupo de Biofisica, Departamento de Fisica U.N.S., Av. Alem 1253, (8000) Bahia Blanca (Argentina); Rey, F.A. [Institut Pasteur, 25 rue du Dr. Roux, F-75724 Paris (France); Guerin, D.M.A. [Unidad de Biofisica (UPV/EHU-CSIC), P.O. Box 644, E-48080 Bilbao (Spain)], E-mail: diego.guerin@ehu.es; Navaza, J. [IBS, Institut de Biologie Structurale Jean-Pierre Ebel, CEA, CNRS, Universite Joseph Fourier, 41 rue Jules Horowitz, F-38027 Grenoble (France)], E-mail: jorge.navaza@ibs.fr

2008-05-25

300

Graphene oxide single sheets as substrates for high resolution cryoTEM.  

PubMed

CryoTEM is an important tool in the analysis of soft matter, where generally defocus conditions are used to enhance the contrast in the images, but this is at the expense of the maximum resolution that can be obtained. Here, we demonstrate the use of graphene oxide single sheets as support for the formation of 10 nm thin films for high resolution cryoTEM imaging, using DNA as an example. With this procedure, the overlap of objects in the vitrified film is avoided. Moreover, in these thin films less background scattering occurs and as a direct result, an increased contrast can be observed in the images. Hence, imaging closer to focus as compared with conventional cryoTEM procedures is achieved, without losing contrast. In addition, we demonstrate an ?1.8 fold increase in resolution, which is crucial for accurate size analysis of nanostructures. PMID:25516333

van de Put, Marcel W P; Patterson, Joseph P; Bomans, Paul H H; Wilson, Neil R; Friedrich, Heiner; van Benthem, Rolf A T M; de With, Gijsbertus; O'Reilly, Rachel K; Sommerdijk, Nico A J M

2015-02-01

301

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. PMID:20634082

De Carlo, Sacha; Harris, J. Robin

2010-01-01

302

Pulse-to-pulse correlation in CryoSat SAR mode radar altimeter echoes from the sea surface  

NASA Astrophysics Data System (ADS)

Serial correlation among successive radar echoes returned from the ocean surface is an important design constraint in satellite altimetry. Walsh [1974, 1982] established the conventional wisdom. Taking the radar footprint to be a uniformly radiating disk, he derived a theoretically expected echo decorrelation time of about 0.5 milliseconds. Following Walsh, ocean altimeters usually employ a pulse repetition frequency (PRF) around 2 kHz, in order to obtain statistically independent echoes at (so it is thought) the maximum possible rate. CryoSat, designed for ranging to ice surfaces, employs a PRF of 18.2 kHz in its SAR mode. CryoSat SAR echo sequences over ocean surfaces can be used to empirically determine the ocean echo decorrelation, and thus to test Walsh's model. Such a test is presented in this paper. The analysis begins by forming the ensemble average of complex cross products of pairs of echoes separated by a time lag L * PRI, where the pulse repetition interval (PRI) is 55 microseconds and the echo lag L runs from 0 to 32. The L = 0 case yields the conventional pulse-limited waveform, which is used to determine the sea state in each ensemble average. The averages of lagged echo cross products reveal the complex coherency, with sampling in both slow time (lag, L), and fast time (range, sampled in waveform gates). Data from many areas and sea states are analyzed, and the results are explained using a simple theory approximating the complex coherency expected from a Gaussian radar pulse. This theory generalizes the classical Brown [1977] waveform model to lagged echo cross products, and generalizes Walsh's work to the case of footprints with non-uniform illumination and diffuse edges. Phase is due to vertical motion of the antenna. Amplitude variations in fast time are due to horizontal motion of the antenna, and are independent of wave height; their functional form confirms Brown's assumption that scattering is independent of azimuth. In slow time, the amplitude decays with lag at a rate that depends on wave height, and without zero crossings. This is in contrast to Walsh's theory, which established the conventional wisdom based on the first zero crossing of Bessel function J1. These results may be applied to determine the optimally weighted average of SAR echoes that yields the best conventional waveform for inter-calibration of SAR and conventional measurements. This calibration is useful for CryoSat and will be necessary for Sentinel-3 and Jason-CS. The present work finds that a conventional altimeter may obtain useful data at rates as high as 9 kHz. This suggests that the interleaved mode option under consideration for Jason-CS could yield optimal conventional measurements as well as simultaneous SAR. I gratefully acknowledge Ron Abileah, Eric Leuliette, John Lillibridge, Laury Miller, Tom Newman and the CryoSat team for helpful discussions.

Smith, W. H.

2012-12-01

303

Preparation of Fe3O4@SiO2@layered double hydroxide core-shell microspheres for magnetic separation of proteins.  

PubMed

Three-component microspheres containing an SiO(2)-coated Fe(3)O(4) magnetite core and a layered double hydroxide (LDH) nanoplatelet shell have been synthesized via an in situ growth method. The resulting Fe(3)O(4)@SiO(2)@NiAl-LDH microspheres display three-dimensional core-shell architecture with flowerlike morphology, large surface area (83 m(2)/g), and uniform mesochannels (4.3 nm). The Ni(2+) cations in the NiAl-LDH shell provide docking sites for histidine and the materials exhibit excellent performance in the separation of a histidine (His)-tagged green fluorescent protein, with a binding capacity as high as 239 ?g/mg. The microspheres show highly selective adsorption of the His-tagged protein from Escherichia coli lysate, demonstrating their practical applicability. Moreover, the microspheres possess superparamagnetism and high saturation magnetization (36.8 emu/g), which allows them to be easily separated from solution by means of an external magnetic field and subsequently reused. The high stability and selectivity of the Fe(3)O(4)@SiO(2)@NiAl-LDH microspheres for the His-tagged protein were retained over several separation cycles. Therefore, this work provides a promising approach for the design and synthesis of multifunctional LDH microspheres, which can be used for the practical purification of recombinant proteins, as well as having other potential applications in a variety of biomedical fields including drug delivery and biosensors. PMID:22191643

Shao, Mingfei; Ning, Fanyu; Zhao, Jingwen; Wei, Min; Evans, David G; Duan, Xue

2012-01-18

304

Yolk-shell nanostructured Fe3O4@NiSiO3 for selective affinity and magnetic separation of His-tagged proteins.  

PubMed

Recent developments of nanotechnology encourage novel materials for facile separations and purifications of recombinant proteins, which are of great importance in disease diagnoses and treatments. We find that Fe3O4@NiSiO3 with yolk-shell nanostructure can be used to specifically purify histidine-tagged (His-tagged) proteins from mixtures of lysed cells with a recyclable process. Each individual nanoparticle composes by a mesoporous nickel silicate shell and a magnetic Fe3O4 core in the hollow inner, which is featured by its great loading efficiency and rapid response toward magnetic fields. The abundant Ni(2+) cations on the shell provide docking sites for selective coordination of histidine and the reversible release is induced by excess imidazole solution. Because of the Fe3O4 cores, the separation, concentration, and recycling of the nanocomposites become feasible under the controls of magnets. These characteristics would be highly beneficial in nanoparticle-based biomedical applications for targeted-drug delivery and biosensors. PMID:25303145

Wang, Yang; Wang, Guangchuan; Xiao, Yun; Yang, Yuling; Tang, Ruikang

2014-11-12

305

A novel magnetically separable TiO{sub 2}/CoFe{sub 2}O{sub 4} nanofiber with high photocatalytic activity under UV-vis light  

SciTech Connect

Graphical abstract: A novel magnetically separable composite photocatalyst TiO{sub 2}/CoFe{sub 2}O{sub 4} nanofiber was prepared by sol-gel method and electrospinning technique, which can be reclaimed with a magnet, and the decolorizing efficiency of MB solution reached 95.87%. Highlights: Black-Right-Pointing-Pointer The composite TiO{sub 2}/CoFe{sub 2}O{sub 4} nanofibers with diameter of 110 {+-} 28 nm have been successfully synthesized by the combination of sol-gel method and electrospinning technique. Black-Right-Pointing-Pointer The presence of Co{sup 2+} or/and Fe{sup 3+} ions may occupy some of the lattice sites of TiO{sub 2} to form an iron-titanium solid solution and narrow the band gap, which broadens the response region of visible light. Black-Right-Pointing-Pointer The resultant nanofibers not only have high decomposition efficiency with methylene blue (MB) under the UV irradiation, which is close to that of Degussa P25, but also can be separated with a magnet and avoid the secondary pollution of the treated water. -- Abstract: A novel magnetically separable heterogeneous photocatalyst TiO{sub 2}/CoFe{sub 2}O{sub 4} nanofiber was prepared by sol-gel method and electrospinning technology, followed by heat treatment at 550 Degree-Sign C for 2 h. The phase structure, morphology and magnetic property of the composite nanofibers were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscope and vibrating sample magnetometer analysis. The photocatalytic studies of TiO{sub 2}/CoFe{sub 2}O{sub 4} fibers suggested that the presence of CoFe{sub 2}O{sub 4} not only enhanced the absorbance of UV light, but also broadened the response region to visible light. The decolorizing efficiency of methylene blue (MB) solution reaches 95.87% over TiO{sub 2}/CoFe{sub 2}O{sub 4} nanofibers under 300 W Hg lamp after 5 h, which is close to that of Degussa P25. Furthermore, these fibers can be collected with a magnet for reuse and effectively avoid the secondary pollution of the treated water.

Li, Cong-Ju, E-mail: congjuli@gmail.com [Beijing Key Laboratory of Clothing Materials R and D and Assessment, Beijing Institute of Fashion Technology, Beijing 100029 (China)] [Beijing Key Laboratory of Clothing Materials R and D and Assessment, Beijing Institute of Fashion Technology, Beijing 100029 (China); Wang, Jiao-Na; Wang, Bin [Beijing Key Laboratory of Clothing Materials R and D and Assessment, Beijing Institute of Fashion Technology, Beijing 100029 (China)] [Beijing Key Laboratory of Clothing Materials R and D and Assessment, Beijing Institute of Fashion Technology, Beijing 100029 (China); Gong, Jian Ru, E-mail: gongjr@nanoctr.cn [National Center for Nanoscience and Technology, China, 11 Zhongguancun Beiyitiao, Beijing 100190 (China); Lin, Zhang [Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fujian 350002 (China)] [Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fujian 350002 (China)

2012-02-15

306

Optimizing Frozen Sample Preparation for Laser Microdissection: Assessment of CryoJane Tape-Transfer System®  

PubMed

Laser microdissection is an invaluable tool in medical research that facilitates collecting specific cell populations for molecular analysis. Diversity of research targets (e.g., cancerous and precancerous lesions in clinical and animal research, cell pellets, rodent embryos, etc.) and varied scientific objectives, however, present challenges toward establishing standard laser microdissection protocols. Sample preparation is crucial for quality RNA, DNA and protein retrieval, where it often determines the feasibility of a laser microdissection project. The majority of microdissection studies in clinical and animal model research are conducted on frozen tissues containing native nucleic acids, unmodified by fixation. However, the variable morphological quality of frozen sections from tissues containing fat, collagen or delicate cell structures can limit or prevent successful harvest of the desired cell population via laser dissection. The CryoJane Tape-Transfer System®, a commercial device that improves cryosectioning outcomes on glass slides has been reported superior for slide preparation and isolation of high quality osteocyte RNA (frozen bone) during laser dissection. Considering the reported advantages of CryoJane for laser dissection on glass slides, we asked whether the system could also work with the plastic membrane slides used by UV laser based microdissection instruments, as these are better suited for collection of larger target areas. In an attempt to optimize laser microdissection slide preparation for tissues of different RNA stability and cryosectioning difficulty, we evaluated the CryoJane system for use with both glass (laser capture microdissection) and membrane (laser cutting microdissection) slides. We have established a sample preparation protocol for glass and membrane slides including manual coating of membrane slides with CryoJane solutions, cryosectioning, slide staining and dissection procedure, lysis and RNA extraction that facilitated efficient dissection and high quality RNA retrieval from CryoJane preparations. CryoJane technology therefore has the potential to facilitate standardization of laser microdissection slide preparation from frozen tissues. PMID:23805281

Golubeva, Yelena G; Smith, Roberta M; Sternberg, Lawrence R

2013-01-01

307

Comparative Cryo-SEM and AFM studies of hylid and rhacophorid tree frog toe pads.  

PubMed

Cryo-scanning electron microscopy (cryo-SEM) and atomic force microscopy (AFM) offer new avenues for the study of the morphology of tree frog adhesive toe pads. Using these techniques, we compare toe pad microstructure in two distantly related species of tree frog, Litoria caerulea, White (Hylidae) and Rhacophorus prominanus, Smith (Rhacophoridae), in which the toe pads are considered to be convergent. AFM demonstrates the extraordinary similarity of both surface microstructures (largely hexagonal epithelial cells surrounded by deep channels) and nanostructures (an array of nanopillars, ca. 350 nm in diameter, all with a small dimple at the apex). The cryo-SEM studies examined the distribution of the fibrillar cytoskeleton within the different layers of the stratified toe pad epithelium, demonstrating that the cytoskeletal elements (keratin tonofilaments) that lie at an angle to the surface are relatively poorly developed in L. caerulea, clearly so in comparison to R. prominanus. Cryo-SEM also enabled the visualization of the fluid layer that is critical to a toe pad's adhesive function. This was achieved by examination of the frozen fluid residues left behind after removal of a toe within the cryo-SEM's experimental chamber. Such 'toeprints' demonstrated the presence of a wedge of fluid surrounding each toe pad, as well as fluid filling the channels that surround each epithelial cell. Cryo-SEM was used to examine epithelial cell shape. In a sample of 582 cells, 59.5% were hexagonal, the remainder being mainly pentagonal (23.1%) or heptagonal (16.1%). The distribution of differently-shaped cells was not random, but was not associated with either pad curvature or the distribution of mucous pores that provide fluid for the frogs' wet adhesion mechanism. Our main finding, the great similarity of toe pad structure in these two species, has important implications for biomimetics, for such convergent evolution suggests a good starting point for attempts to develop adhesives that will function in wet conditions. PMID:23999965

Barnes, W Jon P; Baum, Martina; Peisker, Henrik; Gorb, Stanislav N

2013-12-01

308

Retrofit implementation of Zernike phase plate imaging for cryo-TEM  

PubMed Central

In-focus phase-plate imaging is particularly beneficial for cryo-TEM because it offers a substantial overall increase in image contrast, without an electron dose penalty, and it simplifies image interpretation. We show how phase-plate cryo-TEM can be implemented with an appropriate existing TEM, and provide a basic practical introduction to use of thin-film (carbon) phase plates. We point out potential pitfalls of phase-plate operation, and discuss solutions. We provide information on evaluating a particular TEM for its suitability. PMID:21272647

Marko, Michael; Leith, ArDean; Hsieh, Chyongere; Danev, Radostin

2011-01-01

309

Detection and Quantification of Fluorescent Cell Clusters in Cryo-Imaging  

PubMed Central

We developed and evaluated an algorithm for enumerating fluorescently labeled cells (e.g., stem and cancer cells) in mouse-sized, microscopic-resolution, cryo-image volumes. Fluorescent cell clusters were detected, segmented, and then fit with a model which incorporated a priori information about cell size, shape, and intensity. The robust algorithm performed well in phantom and tissue imaging tests, including accurate (<2% error) counting of cells in mouse. Preliminary experiments demonstrate that cryo-imaging and software can uniquely analyze delivery, homing to an organ and tissue distribution of stem cell therapeutics. PMID:22481905

Steyer, Grant J.; Dong, Feng; Kanodia, Lehar; Roy, Debashish; Penn, Marc; Wilson, David L.

2012-01-01

310

Insights into the capillary electrophoresis separation of heparin disaccharides from nuclear magnetic resonance, pKa, and electrophoretic mobility measurements.  

PubMed

Determination of the pK(a) values of heparin disaccharide functional groups can provide insights into the nature of glycosaminoglycan (GAG)-protein interactions and prove useful for optimization of the charged-based separations typically used in GAG analysis. In order to gain a better understanding into the capillary electrophoresis (CE) separation process, the pK(a) values of the carboxylate and primary amine moieties of 11 heparin disaccharide standards were determined through (1)H NMR detected pH titrations. These pK(a) values were used to calculate the effective net charge of each disaccharide and compared to the electrophoretic mobilities measured by CE. Although a different migration order had been reported by other researchers, our results indicate a strong positive correlation between the two measurements, consistent with the migration order observed in our CE separations. The effect of mutarotation was also examined by (1)H NMR. Mutarotation equilibrium constants favored the alpha anomer over the beta conformation. pK(a) values determined for both anomers of the four disaccharide standards containing a GlcN primary amine indicated that the beta anomer of the GlcN residue was more acidic. Partial separation of these anomers was achieved in CE separations using either formic acid or phosphate buffer. PMID:19653663

Eldridge, Stacie L; Higgins, Layne A; Dickey, Bailey J; Larive, Cynthia K

2009-09-01

311

Nonlinear magnetic response from the Ru0.9Sr2YCu2.1O7.9 magnetosuperconductor and its resultant phase separation  

NASA Astrophysics Data System (ADS)

We investigated the third harmonic nonlinear susceptibility of the Ru0.9Sr2YCu2.1O7.9 magnetosuperconductor and found the presence of two well separated negative peaks. The peak at TM=140K is connected to the previously well known main magnetic ordering of the Ru sublattice, and the peak at around 180K is probably associated with the formation of superparamagnetic particles above TM. The negative signals for both peaks will be discussed in terms of ensuing magnetic orderings of Ru spins at these temperatures. Further, these results will be compared with a recent study of nonlinear susceptibility on RuSr2GdCu2O8.

Živkovi?, I.; Awana, V. P. S.; Kishan, H.; Balamurugan, S.; Takayama-Muromachi, E.; Felner, I.

2007-05-01

312

Cryo-transmission electron microscopy imaging of the morphology of submicrometer aerosol containing organic acids and ammonium sulfate.  

PubMed

The effects of aerosol particles on heterogeneous atmospheric chemistry and climate are determined in part by the internal arrangement of compounds within the particles. To characterize the morphology of internally mixed aerosol particles in the accumulation mode size regime, we have used cryo-transmission electron microscopy to investigate the phase separation behavior of dry, submicrometer particles composed of ammonium sulfate mixed with carboxylic acids (adipic, azelaic, citric, glutaric, malonic, pimelic, suberic, and succinic acid). Determining the morphology of dry particles is important for understanding laboratory studies of aerosol optical properties, reactivity, and cloud condensation nucleus activity, results from field instruments where aerosol particles are dried prior to analysis, and atmospheric processes like deposition mode heterogeneous ice nucleation that occur on dried particles. We observe homogeneous morphologies for highly soluble organic compounds. For organic compounds with limited aqueous solubility, partially engulfed structures are observed. At intermediate aqueous solubilities, small particles are homogeneous and larger particles are partially engulfed. Results are compared to previous studies of liquid-liquid phase separation in supermicrometer particles and the impact of these dry particle morphologies on aerosol-climate interactions are discussed. PMID:24502281

Veghte, Daniel P; Bittner, Danielle Rae; Freedman, Miriam Arak

2014-03-01

313

Separation of the contributions to the magnetization of Tm{sub 1-x}Yb{sub x}B{sub 12} solid solutions in steady and pulsed magnetic fields  

SciTech Connect

The magnetization of substitutional Tm{sub 1-x}Yb{sub x}B{sub 12} 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 Tm{sub 1-x}Yb{sub x}B{sub 12} 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) Multiplication-Sign 10{sup 21} cm{sup -3} meV{sup -1}), and a contribution with saturation in high magnetic fields attributed to the localized magnetic moments ((0.8-3.7){mu}{sub B} per unit cell) of the nanoclusters formed by rare-earth ions with an antiferromagnetic interaction.

Bogach, A. V., E-mail: alex@lt.gpi.ru; Sluchanko, N. E.; Glushkov, V. V.; Demishev, S. V.; Azarevich, A. N.; Filippov, V. B. [Russian Academy of Sciences, Prokhorov General Physics Institute (Russian Federation); Shitsevalova, N. Yu.; Levchenko, A. V. [National Academy of Sciences of Ukraine, Institute of Problems of Materials Science (Ukraine); Vanacken, J.; Moshchalkov, V. V. [Katholieke Universiteit Leuven, Institute of Nanoscale Physics and Chemistry (Belgium); Gabani, S.; Flachbart, K. [Slovak Academy of Sciences, Institute of Experimental Physics (Slovakia)

2013-05-15

314

Atomic Model of Rabbit Hemorrhagic Disease Virus by Cryo-Electron Microscopy and Crystallography  

E-print Network

Atomic Model of Rabbit Hemorrhagic Disease Virus by Cryo-Electron Microscopy and Crystallography Analytical and Testing Center, Beijing Normal University, Beijing, China, 8 School of Medicine, Tsinghua University, Beijing, China Abstract Rabbit hemorrhagic disease, first described in China in 1984, causes

Baker, Timothy S.

315

Direct Visualization of HIV-1 with Correlative Live-Cell Microscopy and Cryo-Electron Tomography  

PubMed Central

SUMMARY Cryo-electron tomography (cryoET) allows 3D visualization of cellular structures at molecular resolution in a close-to-native state, and therefore has the potential to help elucidate early events of HIV-1 infection in host cells. However, direct observation of structural details of infecting HIV-1 has not been realized due to technological challenges in working with rare and dynamic HIV-1 particles in human cells. Here, we report structural analysis of HIV-1 and host-cell interactions by developing a correlative high-speed 3D live-cell imaging and cryoET method. Using this methodology, we showed, for the first time under near-native conditions, that intact hyperstable mutant HIV-1 cores are released into the cytoplasm of host-cells. We further obtained direct evidence to suggest that a hyperstable mutant capsid, E45A, delayed capsid disassembly compared to the wild-type capsid. Together, these results demonstrate the advantage of our correlative live-cell and cryoET approach to image dynamic processes, such as viral infection. PMID:22078557

Jun, Sangmi; Ke, Danxia; Debiec, Karl; Zhao, Gongpu; Meng, Xin; Ambrose, Zandrea; Gibson, Gregory A.; Watkins, Simon C.; Zhang, Peijun

2011-01-01

316

Single Particle Cryo-electron Microscopy and 3-D Reconstruction of Viruses  

PubMed Central

With fast progresses in instrumentation, image processing algorithms, and computational resources, single particle electron cryo-microscopy (cryo-EM) 3-D reconstruction of icosahedral viruses has now reached near-atomic resolutions (3–4 Å). With comparable resolutions and more predictable outcomes, cryo-EM is now considered a preferred method over X-ray crystallography for determination of atomic structure of icosahedral viruses. At near-atomic resolutions, all-atom models or backbone models can be reliably built that allow residue level understanding of viral assembly and conformational changes among different stages of viral life cycle. With the developments of asymmetric reconstruction, it is now possible to visualize the complete structure of a complex virus with not only its icosahedral shell but also its multiple non-icosahedral structural features. In this chapter, we will describe single particle cryo-EM experimental and computational procedures for both near-atomic resolution reconstruction of icosahedral viruses and asymmetric reconstruction of viruses with both icosahedral and non-icosahedral structure components. Procedures for rigorous validation of the reconstructions and resolution evaluations using truly independent de novo initial models and refinements are also introduced. PMID:24357374

Guo, Fei; Jiang, Wen

2014-01-01

317

Technical Notes NOAA/NESDIS LSA CryoSat Interim Geophysical Data Record (IGDR)  

E-print Network

scientific utilization of the data with the stipulation that the users of the data agree to follow the policy-Real-Time ocean forecast products and platform attitude (http://ibis%20WHFSmith_NRT_CS2.pdf) Retracking range, SWH, sigma-naught, and attitude in CryoSat conventional ocean data

318

Cryo-milling of starch granules leads to differential effects on molecular size and conformation  

Microsoft Academic Search

Milling of starch granules is important for many food applications and involves a combination of mechanical and thermal energy. In order to understand the effects of mechanical force alone, four commercial starches including maize starch (MS), potato starch (PS), and two high amylose maize starches (HAMS) (Gelose 50 and Gelose 80) were cryo-milled for 20min under the same conditions. The

Sushil Dhital; Ashok K. Shrestha; Bernadine M. Flanagan; Jovin Hasjim; Michael J. Gidley

2011-01-01

319

Lessons Learned During the Integration Phase of the NASA IN-STEP Cryo System Experiment  

NASA Technical Reports Server (NTRS)

The Cryo System Experiment (CSE), a NASA In-Space Technology Experiments Proram (IN-STEP) Class D Flight Experiment, was developed by Hughes Aircraft Company (Hughes) to validate in zero-g space a 65 K cryogenic system for focal planes, optics, instruments, or other equipment (gramma-ray spectrometers and infrared and submillimeter imaging instruments) that require continuous cryogenic cooling.

Sugimura, R. S.; Russo, S. C.; Gilman, D. C.

1994-01-01

320

Characterization of model soil colloids by cryo-scanning electron microscopy  

E-print Network

applied to humic and fulvic acids and to humic­clay complexes (Chen and Schnitzer, 1976). Cryo: a soil humic acid, a commercial smectite, a synthetic ferrihydrite and their binary and ternary and dimensions, and the humic acid exhibited a sponge-like structure. The micromorphology of the ferrihydrite

Boyer, Edmond

321

Controlling protein adsorption on graphene for cryo-EM using low-energy hydrogen plasmas  

E-print Network

Controlling protein adsorption on graphene for cryo-EM using low-energy hydrogen plasmas Christopher J. Russo1 and Lori A. Passmore1 1Medical Research Council Laboratory of Molecular Biology taken before and after 80 s hydrogen plasma treatment used to measure change in lattice constant vis

Cai, Long

322

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

NASA Astrophysics Data System (ADS)

We are developing enhanced volume rendering techniques for color image data. One target application is cryo-imaging, which provides whole-mouse, micron-scale, anatomical color, and molecular fluorescence image volumes by alternatively sectioning and imaging the frozen tissue block face. With the rich color images provided by cryo-imaging, we use true-color volume rendering and visually enhance anatomical regions by proper selection of voxel opacity. To compute opacity, we use color and/or gradient feature detection followed by suitable opacity transfer functions (OTF). An interactive user interface allows one to select from among multiple color and gradient feature detectors, OTF's, and their associated parameters, and to compute in live time new volume visualizations from within the Amira platform. We are also developing multi-resolution volume rendering techniques to accommodate extremely large (>~60GB) cryo-image data sets. Together, these enhancements enable us to interactively interrogate cryo-image volume data and create useful renderings with "implicit segmentation" of organs.

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

2009-02-01

323

Description and comparison of algorithms for correcting anisotropic magnification in cryo-EM images  

E-print Network

Single particle electron cryomicroscopy (cryo-EM) allows for structures of proteins and protein complexes to be determined from images of non-crystalline specimens. Cryo-EM data analysis requires electron microscope images of randomly oriented ice-embedded protein particles to be rotated and translated to allow for coherent averaging when calculating three-dimensional (3-D) structures. Rotation of 2-D images is usually done with the assumption that the magnification of the electron microscope is the same in all directions, a condition that has been found to be untrue with some electron microscopes when used with the settings necessary for cryo-EM with a direct detector device (DDD) camera (Grant and Grigorieff, in preparation). Correction of images by linear interpolation in real space has allowed high-resolution structures to be calculated from cryo-EM images for symmetric particles (Grant and Grigorieff, in preparation). Here we describe and compare a simple real space method and a somewhat more sophisticat...

Zhao, Jianhua; Benlekbir, Samir; Rubinstein, John L

2015-01-01

324

Modification of the method for cryo-preservation of rumen anaerobic fungi  

E-print Network

Modification of the method for cryo-preservation of rumen anaerobic fungi V Kostyukovsky Y Nakai fungi penetrate and degrade efficiently plant cell walls in the alimentary tract of herbivores-preservation of the fungi by deep freezing in liquid nitrogen with 5 % (v/v) dimethyl sulfoxide (DMSO) as a protecting agent

Paris-Sud XI, Université de

325

The cryo-penetrator: An approach to exploration of icy bodies in the solar system  

Microsoft Academic Search

The nuclei of comets and the small icy moons of the outer planets are thought to be the most primitive objects in the solar system. Because of their pristine nature, in-situ measurements of composition, temperature, and mechanical properties will be a powerful tool in realization of one of NASA's major objectives: determination of the Solar System's origins and evolution.Cryo penetrators

W. V. Boynton; R. P. Reinert

1995-01-01

326

A cryoSEM Method for Preservation and Visualization of Calcified Shark Cartilage  

E-print Network

in a backscatter electron micrograph where calcified tissue is white) are greatly distorted by collapseA cryoSEM Method for Preservation and Visualization of Calcified Shark Cartilage (And OtherSEM the calci- fied cartilage of sharks and rays (elasmobranch fishes), a layered biocomposite that has

Summers, Adam P.

327

Cryo-EM of macromolecular assemblies at near-atomic resolution  

PubMed Central

With single-particle electron cryomicroscopy (cryo-eM), it is possible to visualize large, macromolecular assemblies in near-native states. although subnanometer resolutions have been routinely achieved for many specimens, state of the art cryo-eM has pushed to near-atomic (3.3–4.6 Å) resolutions. at these resolutions, it is now possible to construct reliable atomic models directly from the cryo-eM density map. In this study, we describe our recently developed protocols for performing the three-dimensional reconstruction and modeling of Mm-cpn, a group II chaperonin, determined to 4.3 Å resolution. this protocol, utilizing the software tools eMan, Gorgon and coot, can be adapted for use with nearly all specimens imaged with cryo-eM that target beyond 5 Å resolution. additionally, the feature recognition and computational modeling tools can be applied to any near-atomic resolution density maps, including those from X-ray crystallography. PMID:20885381

Baker, Matthew L; Zhang, Junjie; Ludtke, Steven J; Chiu, Wah

2011-01-01

328

Phase-separation-induced changes in the magnetic and transport properties of the quaternary Heusler alloy Co2Mn1-xTixSn  

NASA Astrophysics Data System (ADS)

The quaternary Heusler compound Co2Mn1-xTixSn with x=0 , 0.2, 0.4, 0.5, 0.6, 0.8, and 1 shows a phase separation into the two Heusler compounds, Co2MnSn and Co2TiSn . Only at the edges of the composition range a slight admixture of Mn and Ti to the respective other phase is observed. This phase separation leads to a distinct microstructure which can be altered by the composition of the material. Pronounced changes in the magnetic and electronic properties take place with varying composition. Two magnetic transitions occur which indicate different Curie temperatures for both phases. The reduction in the thermal lattice conductivity is of particular interest for an optimization of Heusler compounds for thermoelectric applications. In the field of spintronics the use of superlattices composed of Co2MnSn and Co2TiSn without any interlayer diffusion is suggested.

Graf, Tanja; Barth, Joachim; Blum, Christian G. F.; Balke, Benjamin; Felser, Claudia; Klaer, Peter; Elmers, Hans-Joachim

2010-09-01

329

Sonochemical synthesis and characterization of magnetic separable Fe3O4–TiO2 nanocomposites and their catalytic properties  

Microsoft Academic Search

A novel sonochemical method is described for the preparation of Fe3O4–TiO2 photocatalysts in which nanocrystalline titanium dioxide particles are directly coated onto a magnetic core. The Fe3O4 nanoparticles were partially embedded in TiO2 agglomerates. TiO2 nanocrystallites were obtained by hydrolysis and condensation of titanium tetraisopropyl in the presence of ethanol and water under high-intensity ultrasound irradiation. This method is attractive

Wanquan Jiang; Xueping Zhang; Xinglong Gong; Fangfang Yan; Zhong Zhang

2010-01-01

330

The general concept of signal–noise separation (SNS): mathematical aspects and implementation in magnetic resonance spectroscopy  

Microsoft Academic Search

Magnetic resonance spectroscopy (MRS) and spectroscopic imaging (MRSI) are increasingly recognized as potentially key modalities\\u000a in cancer diagnostics. It is, therefore, urgent to overcome the shortcomings of current applications of MRS and MRSI. We explain\\u000a and substantiate why more advanced signal processing methods are needed, and demonstrate that the fast Padé transform (FPT),\\u000a as the quotient of two polynomials, is

Dževad Belki?; Karen Belki?

2009-01-01

331

Fabrication of magnetically separable fluorescent terbium-based MOF nanospheres for highly selective trace-level detection of TNT.  

PubMed

In this work, we present novel kinds of Fe3O4@Tb-BTC magnetic metal-organic framework (MOF) nanospheres which possess both magnetic characteristics and fluorescent properties using a layer by layer assembly technique. The structure and morphology of the as-prepared Fe3O4@Tb-BTC were systematically characterized and it was applied in detection of nitroaromatic explosives, such as 2,4-dinitrotoluene (2,4-DNT), 2,6-dinitrotoluene (2,6-DNT), 2-nitrotoluene (2-NT), 4-nitrotoluene (4-NT), nitrobenzene (NB) and picric acid (PA). The results indicate that the fluorescence intensity of Fe3O4@Tb-BTC can be quenched by all analytes studied in the present work. Remarkably, the as-synthesized nanospheres exhibit high sensitivity for 2,4,6-trinitrotoluene (TNT) detection with Ksv value of (94?800 M(-1)). Besides, the magnetic nanospheres can be easily recycled, which makes it more convenient for reutilization and friendly to the environment. The results show that it has broad application prospects in the detection of nitroaromatic explosives. PMID:24452313

Qian, Jing-Jing; Qiu, Ling-Guang; Wang, Yi-Min; Yuan, Yu-Peng; Xie, An-Jian; Shen, Yu-Hua

2014-03-14

332

Phase separation and suppression of the structural and magnetic transitions in superconducting doped iron tellurides, Fe(1+x)Te(1-y)S(y).  

PubMed

Single crystal and powder samples of the series of iron chalcogenide superconductors with nominal composition, Fe((1.15))Te((1-)y)S(y), are found to form for 0 ? y ? 0.15. They crystallize in the tetragonal anti-PbO structure, which is composed of layers of edge-shared Fe(Te, S)(4) tetrahedra. For y = 0, Fe(1+x)Te (x ? 0.12(1)) is nonsuperconducting and undergoes a tetragonal (P4/nmm) to monoclinic (P2(1)/m) structural transition at ?65 K, associated with the onset of commensurate antiferromagnetic order at q = (0.5 0 0.5). We show that on sulfur substitution, Fe(1+x)Te(1-y)S(y) becomes orthorhombic (Pmmn) at low temperature for 0 ? y ? 0.015, where the greatly suppressed magnetic scattering is now incommensurate at q = (0.5-? 0 0.5) and possesses short ranged magnetic correlations that are well fitted with a two-dimensional Warren peak shape. At much higher concentrations of S (y ? 0.075), there is suppression of both the structural and magnetic transitions and a superconducting transition at 9 K is observed. Between these two composition regimes, there exists a region of phase separation (0.025 ? y ? 0.05), where the low temperature neutron diffraction data is best refined with a model containing both the tetragonal and orthorhombic phases. The increase in the amount of sulfur is found to be associated with a reduction in interstitial iron, x. Microprobe analysis of a single crystal of composition Fe((1.123(5)))Te((0.948(4)))S((0.052(4))) confirms the presence of compositional variation within the crystals, rationalizing the observed phase separation. PMID:20806923

Zajdel, Pawel; Hsieh, Ping-Yen; Rodriguez, Efrain E; Butch, Nicholas P; Magill, Jeff D; Paglione, Johnpierre; Zavalij, Peter; Suchomel, Matthew R; Green, Mark A

2010-09-22

333

Time series over the Brahmaputra River from CryoSat-2/SIRAL altimetry  

NASA Astrophysics Data System (ADS)

CryoSat-2 was launched in 2010 with the purpose of monitoring polar ice caps, but the satellite has also proven to be useful for studies at lower latitudes. CryoSat-2 carries a new type of instrument, the SIRAL altimeter, which implements SAR and SARIn mode in addition to the standard LRM. In these modes the along-track resolution is 300m, giving rise to new opportunities for inland water altimetry, which requires a high along-track resolution in order to accurately capture the return signals from the water bodies. Here, we have investigated the possibilities for monitoring river water levels with CryoSat-2 as a part of the EU FP7 LOTUS (Preparing Land and Ocean Take Up from Sentinel-3). The LOTUS project will develop new methodologies, data processing chains, and applications of the SAR mode data for the inland water levels in rivers and lakes. Time series analysis for CryoSat-2 altimetry is not straightforward due to the satellite's very long repeat period of 369 days. It is therefore necessary to take new methods into use. Using slope correction, i.e. taking advantage of the drifting orbit, we have derived time series from retracked heights in all three modes of the CryoSat-2 altimeter over the Brahmaputra River. From the time series we can estimate the amplitude and the seasonal signal of the flow in the river. Presented here is a comparison of the results between modes and with Envisat time series.

Villadsen, Heidi; Baltazar Andersen, Ole; Knudsen, Per; Nielsen, Karina; Stenseng, Lars

2014-05-01

334

Limiting factors in atomic resolution cryo electron microscopy: No simple tricks  

PubMed Central

To bring cryo electron microscopy (cryoEM) of large biological complexes to atomic resolution, several factors – in both cryoEM image acquisition and 3D reconstruction – that may be neglected at low resolution become significantly limiting. Here we present thorough analyses of four limiting factors: (a) electron-beam tilt, (b) inaccurate determination of defocus values, (c) focus gradient through particles, and (d) particularly for large particles, dynamic (multiple) scattering of electrons. We also propose strategies to cope with these factors: (a) the divergence and direction tilt components of electron-beam tilt could be reduced by maintaining parallel illumination and by using a coma-free alignment procedure, respectively. Moreover, the effect of all beam tilt components, including spiral tilt, could be eliminated by use of a spherical aberration corrector. (b) More accurate measurement of defocus value could be obtained by imaging areas adjacent to the target area at high electron dose and by measuring the image shift induced by tilting the electron beam. (c) Each known Fourier coefficient in the Fourier transform of a cryoEM image is the sum of two Fourier coefficients of the 3D structure, one on each of two curved ‘characteristic surfaces’ in 3D Fourier space. We describe a simple model-based iterative method that could recover these two Fourier coefficients on the two characteristic surfaces. (d) The effect of dynamic scattering could be corrected by deconvolution of a transfer function. These analyses and our proposed strategies offer useful guidance for future experimental designs targeting atomic resolution cryoEM reconstruction. PMID:21627992

Zhang, Xing; Zhou, Z. Hong

2013-01-01

335

3D Cryo-Imaging: A Very High-Resolution View of the Whole Mouse  

PubMed Central

We developed the Case Cryo-imaging system that provides information rich, very high-resolution, color brightfield, and molecular fluorescence images of a whole mouse using a section-and-image block-face imaging technology. The system consists of a mouse-sized, motorized cryo-microtome with special features for imaging, a modified, brightfield/ fluorescence microscope, and a robotic xyz imaging system positioner, all of which is fully automated by a control system. Using the robotic system, we acquired microscopic tiled images at a pixel size of 15.6 µm over the block face of a whole mouse sectioned at 40 µm, with a total data volume of 55 GB. Viewing 2D images at multiple resolutions, we identified small structures such as cardiac vessels, muscle layers, villi of the small intestine, the optic nerve, and layers of the eye. Cryo-imaging was also suitable for imaging embryo mutants in 3D. A mouse, in which enhanced green fluorescent protein was expressed under gamma actin promoter in smooth muscle cells, gave clear 3D views of smooth muscle in the urogenital and gastrointestinal tracts. With cryo-imaging, we could obtain 3D vasculature down to 10 µm, over very large regions of mouse brain. Software is fully automated with fully programmable imaging/sectioning protocols, email notifications, and automatic volume visualization. With a unique combination of field-of-view, depth of field, contrast, and resolution, the Case Cryo-imaging system fills the gap between whole animal in vivo imaging and histology. PMID:19248166

Roy, Debashish; Steyer, Grant J.; Gargesha, Madhusudhana; Stone, Meredith E.; Wilson, David L.

2009-01-01

336

Imaging System for Creating 3D Block-Face Cryo-Images Of Whole Mice  

PubMed Central

We developed a cryomicrotome/imaging system that provides high resolution, high sensitivity block-face images of whole mice or excised organs, and applied it to a variety of biological applications. With this cryo-imaging system, we sectioned cryo-preserved tissues at 2?40 ?m thickness and acquired high resolution brightfield and fluorescence images with microscopic in-plane resolution (as good as 1.2 ?m). Brightfield images of normal and pathological anatomy show exquisite detail, especially in the abdominal cavity. Multi-planar reformatting and 3D renderings allow one to interrogate 3D structures. In this report, we present brightfield images of mouse anatomy, as well as 3D renderings of organs. For BPK mice model of polycystic kidney disease, we compared brightfield cryo-images and kidney volumes to MRI. The color images provided greater contrast and resolution of cysts as compared to in vivo MRI. We note that color cryo-images are closer to what a researcher sees in dissection, making it easier for them to interpret image data. The combination of field of view, depth of field, ultra high resolution and color/fluorescence contrast enables cryo-image volumes to provide details that cannot be found through in vivo imaging or other ex vivo optical imaging approaches. We believe that this novel imaging system will have applications that include identification of mouse phenotypes, characterization of diseases like blood vessel disease, kidney disease, and cancer, assessment of drug and gene therapy delivery and efficacy and validation of other imaging modalities. PMID:19802364

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

2009-01-01

337

Search for order in magnetic dispersions: Magnetic field and shear induced particle orientations  

NASA Astrophysics Data System (ADS)

Magnetic tapes are manufactured by a coating process where a magnetic dispersion is cast onto a polymer base film. Immediately after coating the wet films are subjected to a magnetic field that orients the rod-like magnetic particles parallel to the machine direction of the tape. In reality there is a distribution of particle orientations. Our interest in increasing the particle orientation order in magnetic tape has led us to search for methods of achieving high particle orientation order in magnetic dispersions. An understanding of the particle orientation order in the dispersion is of great importance in controlling the properties of the final product. Inspired by a mean field model and cryo-VSM technique, we have developed an experimental method to measure the degree of particle orientation order in magnetic dispersions, which can not only reveal the quality of dispersion quantitatively, but also help refine existing theoretical models. In this method, the angular dependence remanence of a frozen magnetic dispersion sample is measured using a vibrating sample magnetometer, and then the degree of particle order orientation can be calculated from those experimental results. The effect of the external magnetic field on the particle orientation of the magnetic dispersion is investigated using the technique of cryo-VSM. The effect of the particle loading is also investigated. We also compare the cryo-VSM results to the calculated orientation order parameter from the single particle mean field model developed by Bhandar and Wiest. Small angle neutron scattering measurements were performed to investigate effects of the magnetic field and shear flow on the orientation order of particles in magnetic dispersions. The order parameter S obtained by the SANS agreed well with the values obtained by the cryo-VSM method. We also introduce Dr. Mankey's idea to model the SANS experimental data. The particle size distributions are considered in Dr. Mankey's model.

He, Bin

338

Using shell-tunable mesoporous Fe3O4@HMS and magnetic separation to remove DDT from aqueous media.  

PubMed

1,1-bis(4-chlorophenyl)-2,2,2-trichloroethane (DDT) is of concern in water treatment because of its persistence and health effects. A new concept is proposed to synthesize hexagonal mesoporous silica (HMS) with magnetic functionalization for DDT removal from aqueous media. Fe(3)O(4) nanocrystals were synthesized by a low-temperature solvothermal process, and then encapsulated in mesoporous silica through a packing approach, forming core-shell structured Fe(3)O(4)@HMS microspheres. The synthesized materials were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM) and nitrogen adsorption-desorption techniques. The results indicate that the silica shell conserves mesoporous structure after the removal of surfactant templates. Different from previous studies, the thickness, pore volume and surface area of silica shell can be controlled by adjusting the reaction condition. These Fe(3)O(4)@HMS materials show high adsorption capacity and fast adsorption rate for DDT. Because of the useful magnetic property and unique mesoporous structure, the synthesized materials provide a fast, convenient and highly efficient means to remove DDT from aqueous media. PMID:19586720

Tian, Hua; Li, Jinjun; Shen, Qun; Wang, Hailin; Hao, Zhengping; Zou, Linda; Hu, Qin

2009-11-15

339

A collaborative framework for 3D alignment and classification of heterogeneous subvolumes in cryo-electron tomography  

PubMed Central

The limitation of using low electron doses in non-destructive cryo-electron tomography of biological specimens can be partially offset via averaging of aligned and structurally homogeneous subsets present in tomograms. This type of sub-volume averaging is especially challenging when multiple species are present. Here, we tackle the problem of conformational separation and alignment with a “collaborative” approach designed to reduce the effect of the “curse of dimensionality” encountered in standard pair-wise comparisons. Our new approach is based on using the nuclear norm as a collaborative similarity measure for alignment of sub-volumes, and by exploiting the presence of symmetry early in the processing. We provide a strict validation of this method by analyzing mixtures of intact simian immunodeficiency viruses SIV mac239 and SIV CP-MAC. Electron microscopic images of these two virus preparations are indistinguishable except for subtle differences in conformation of the envelope glycoproteins displayed on the surface of each virus particle. By using the nuclear norm-based, collaborative alignment method presented here, we demonstrate that the genetic identity of each virus particle present in the mixture can be assigned based solely on the structural information derived from single envelope glycoproteins displayed on the virus surface. PMID:23110852

Kuybeda, Oleg; Frank, Gabriel A.; Bartesaghi, Alberto; Borgnia, Mario; Subramaniam, Sriram; Sapiro, Guillermo

2012-01-01

340

Crystal and cryoEM structural studies of a cell wall degrading enzyme in the bacteriophage [psi]29 tail  

SciTech Connect

The small bacteriophage {phi}29 must penetrate the {approx}250-{angstrom} thick external peptidoglycan cell wall and cell membrane of the Gram-positive Bacillus subtilis, before ejecting its dsDNA genome through its tail into the bacterial cytoplasm. The tail of bacteriophage {phi}29 is noncontractile and {approx}380 {angstrom} long. A 1.8-{angstrom} resolution crystal structure of gene product 13 (gp13) shows that this tail protein has spatially well separated N- and C-terminal domains, whose structures resemble lysozyme-like enzymes and metallo-endopeptidases, respectively. CryoEM reconstructions of the WT bacteriophage and mutant bacteriophages missing some or most of gp13 shows that this enzyme is located at the distal end of the {phi}29 tail knob. This finding suggests that gp13 functions as a tail-associated, peptidoglycan-degrading enzyme able to cleave both the polysaccharide backbone and peptide cross-links of the peptidoglycan cell wall. Comparisons of the gp13{sup -} mutants with the {phi}29 mature and emptied phage structures suggest the sequence of events that occur during the penetration of the tail through the peptidoglycan layer.

Xiang, Ye; Morais, Marc C.; Cohen, Daniel N.; Bowman, Valorie D.; Anderson, Dwight L.; Rossmann, Michael G. (Purdue); (UMM)

2009-08-28

341

Drive tube 60009 - A chemical study of magnetic separates of size fractions from five strata. [lunar soil analysis  

NASA Technical Reports Server (NTRS)

Each bulk soil and both the magnetic and nonmagnetic components of the 90-150 micron and below 20 micron fractions of five soils from drive tube 60009 were analyzed. Samples were analyzed for FeO, Na2O, Sc, Cr, Co, Ni, Hf, Ta, Th, La, Ce, Sm, Eu, Tb, Yb, and Lu by neutron activation analysis. Several samples were fused and analyzed for major elements by electron microprobe analysis. Compositional variations are not systematically related to depth. The compositions of the five soils studied are well explained by a two-component mixing model whose end members are a submature Apollo 16-type soil and an extremely immature anorthositic material similar to 60025. There is evidence that the anorthositic component had received a small amount of exposure before these soils were mixed. After mixing, the soils received little exposure suggesting mixing and deposition on a rapid time scale.

Blanchard, D. P.; Jacobs, J. W.; Brannon, J. C.; Brown, R. W.

1976-01-01

342

The performance of CryoSat-2 as an ocean altimeter  

NASA Astrophysics Data System (ADS)

Two years after the launch of CryoSat-2, oceanographic uses of the CryoSat-2 data have well taken off, after several institutes, NOAA included, have spent a dedicated effort to upgrade the official CryoSat-2 data products to a level that is suitable for monitoring of mesoscale phenomena, as well as wind speed and wave height. But in the coastal areas, this is much less the case. This is mostly the result of the fact that CryoSat-2 is running in SAR or InSAR mode in many of the focus areas, like the Mediterranean Sea. We have shown, however, that the CryoSat data is intrinsically of high quality and for over a year now have been producing "IGDR" type data through FTP and through RADS. These steps include: ? Combine final (LRM) and fast-delivery (FDM) products and split the segmented files into pass files. ? Divide the 369-day repeat cycle into subcycles of 29 or 27 days. ? Retrack the conventional low-rate data to determine range, significant wave height, backscatter (and off-nadir angle). ? Add or replace the usual corrections for ionospheric and atmospheric delays, tides, dynamic atmospheric correction, sea state bias, mean sea surface. ? Update orbits and corrections whenever they become available. This way NOAA produces an "IGDR" product from the fast-delivery FDM and the CNES MOE orbit in about 2 days after real time, and a "GDR" product from the final LRM data and the CNES POE orbit with a delay of about 1 month. In order to extend the data products to the coastal regime, we have developed a process in which the SAR data are first combined to "Pseudo-LRM" or "reduced SAR" wave forms, that are similar to the conventional low-rate wave forms. After this the reduced SAR data are retracked and combined with the conventional data to form a harmonised product. Although this sounds relatively straightforward, many steps were needed to get this done: ? Combine the SAR wave forms to conventional wave forms, without loss of information. ? Reconstruct backscatter and significant wave height in a meaningful way, consistent with low-rate data. ? Cross-calibrate the conventional and SAR mode data. ? Validate the data quality of conventional and SAR mode data through crossovers and collinear track analyses. In this presentation we will demonstrate how the CryoSat-2 data quality compares to other altimeters (Envisat, Jason-1 and Jason-2) by means of data distribution maps, histograms and crossover comparisons.

Scharroo, R.; Smith, W. H.; Leuliette, E. W.; Lillibridge, J. L.

2012-12-01

343

Distinct constrictive processes, separated in time and space,divide Caulobacter inner and outer membranes  

SciTech Connect

Cryo-electron microscope tomography (cryoEM) and a fluorescence loss in photobleaching (FLIP) assay were used to characterize progression of the terminal stages of Caulobacter crescentus cell division. Tomographic cryoEM images of the cell division site show separate constrictive processes closing first the inner, and then the outer, membrane in a manner distinctly different from septum-forming bacteria. The smallest observed pre-fission constrictions were 60 nm for both the inner and outer membrane. FLIP experiments had previously shown cytoplasmic compartmentalization, when cytoplasmic proteins can no longer diffuse between the two nascent progeny cell compartments, occurring 18 min before daughter cell separation in a 135 min cell cycle. Here, we used FLIP experiments with membrane-bound and periplasmic fluorescent proteins to show that (1) periplasmic compartmentalization occurs after cytoplasmic compartmentalization, consistent with the cryoEM observations, and (2) inner membrane and periplasmic proteins can diffuse past the FtsZ constriction site, indicating that the cell division machinery does not block membrane diffusion.

Judd, Ellen M.; Comolli, Luis R.; Chen, Joseph C.; Downing,Kenneth H.; Moerner, W.E.; McAdams, Harley H.

2005-05-01

344

Fe{sub 3}O{sub 4}@graphene oxide composite: A magnetically separable and efficient catalyst for the reduction of nitroarenes  

SciTech Connect

Highlights: ? The Fe{sub 3}O{sub 4}@GO composite was prepared by a facile co-precipitation method. ? Fe{sub 3}O{sub 4} nanoparticles are well distributed on GO nanosheets. ? Fe{sub 3}O{sub 4}@GO was for the first time explored as a catalyst to reduce nitroarenes. ? Fe{sub 3}O{sub 4}@GO exhibits higher catalytic activity. ? The composite catalyst is easily recycled due to its magnetic separability. - Abstract: We reported a facile co-precipitation method to prepare a highly active Fe{sub 3}O{sub 4}@graphene oxide (Fe{sub 3}O{sub 4}@GO) composite catalyst, which was fully characterized by means of X-ray diffraction (XRD), Fourier transformed infrared (FTIR) spectroscopy, transmission electron microscopy (TEM) and N{sub 2} adsorption–desorption measurements. The results demonstrated that the Fe{sub 3}O{sub 4} nanoparticles (Fe{sub 3}O{sub 4} NPs) with a small diameter of around 12 nm were densely and evenly deposited on the graphene oxide (GO) sheets. The as-prepared Fe{sub 3}O{sub 4}@GO composite was explored as a catalyst to reduce a series of nitroarenes for the first time, which exhibited a great activity with a turnover frequency (TOF) of 3.63 min{sup ?1}, forty five times that of the commercial Fe{sub 3}O{sub 4} NPs. The dosages of catalyst and hydrazine hydrate are both less than those reported. Furthermore, the composite catalyst can be easily recovered due to its magnetic separability and high stability.

He, Guangyu [Jiangsu Key Laboratory of Advanced Catalytic Materials and Technology, Changzhou University, Jiangsu Province, Changzhou 213164 (China); Key Laboratory of Ministry of Education for Soft Chemistry and Functional Materials, Nanjing University of Science and Technology, Nanjing 210094 (China); Liu, Weifeng; Sun, Xiaoqiang [Jiangsu Key Laboratory of Advanced Catalytic Materials and Technology, Changzhou University, Jiangsu Province, Changzhou 213164 (China); Chen, Qun, E-mail: chenqunjpu@yahoo.com [Jiangsu Key Laboratory of Advanced Catalytic Materials and Technology, Changzhou University, Jiangsu Province, Changzhou 213164 (China); Wang, Xin [Key Laboratory of Ministry of Education for Soft Chemistry and Functional Materials, Nanjing University of Science and Technology, Nanjing 210094 (China); Chen, Haiqun, E-mail: hqchenyf@hotmail.com [Jiangsu Key Laboratory of Advanced Catalytic Materials and Technology, Changzhou University, Jiangsu Province, Changzhou 213164 (China)

2013-05-15

345

Magnetism  

NSDL National Science Digital Library

This webpage is part of the University Corporation for Atmospheric Research (UCAR) Windows to the Universe program. It describes the nature and configuration of magnetic fields, which are the result of moving electric charges, including how they cause magnetic objects to orient themselves along the direction of the magnetic force points, which are illustrated as lines. Magnetic field lines by convention point outwards at the north magnetic pole and inward at the south magnetic pole. The site features text, scientific illustrations and an animation. Text and vocabulary are selectable for the beginning, intermediate, or advanced reader.

Team, University C.

2007-12-12

346

Optimization of a phase separation based magnetic-stirring salt-induced liquid-liquid microextraction method for determination of fluoroquinolones in food.  

PubMed

Herein, we developed a novel integrated apparatus to perform phase separation based on magnetic-stirring, salt-induced, liquid-liquid microextraction for determination of five fluoroquinolones in animal-based foods by HPLC analysis. The novel integrated apparatus consisted of three simple HDPE (high density polyethylene) parts that were used to separate the solvent from the aqueous solution prior to retrieving the extractant. The extraction parameters were optimized using the response surface method based on central composite design: 791?L of acetone solvent, 2.5g of Na2SO4, pH 1.7, 3.0min of stir time, and 5.5min centrifugation. The limits of detection were 0.07-0.53?gkg(-1) and recoveries were 91.6-105.0% for the five fluoroquinolones from milk, eggs and honey. This method is easily constructed from inexpensive materials, extraction efficiency is high, and the approach is compatible with HPLC analysis. Thus, it has excellent prospects for sample pre-treatment and analysis of fluoroquinolones in animal-based foods. PMID:25577068

Gao, Ming; Wang, Huili; Ma, Meiping; Zhang, Yuna; Yin, Xiaohan; Dahlgren, Randy A; Du, Dongli; Wang, Xuedong

2015-05-15

347

Ionic liquid coated magnetic core/shell Fe3O4@SiO2 nanoparticles for the separation/analysis of linuron in food samples  

NASA Astrophysics Data System (ADS)

Three hydrophobic ionic liquids (ILs) including 1-butyl-3-methylimidazole hexafluorophosphate ([BMIM]PF6), 1-hexyl-3-methyl-imidazole hexafluorophosphate ([HMIM]PF6), and 1-octyl-3-methylimidazole hexafluoro-phosphate ([OMIM]PF6) coated Fe3O4@SiO2 nanoparticles with core-shell structure to prepare magnetic solid phase extraction agent (Fe3O4@SiO2@ILs) and establish a new method of magnetic solid phase extraction (MSPE) coupled with UV spectrometry for separation/analysis of linuron. The results showed that linuron was adsorbed rapidly by Fe3O4@SiO2@[OMIM]PF6 and eluanted by ethanol. Under the optimal conditions, preconcentration factor of the proposed method was 10-fold. The linear range, detection limit, correlation coefficient (R) and relative standard deviation (RSD) were found to be 0.04-20.00 ?g mL-1, 5.0 ng mL-1, 0.9993 and 2.8% (n = 3, c = 4.00 ?g mL-1), respectively. The Fe3O4@SiO2 nanoparticles could be used repeatedly for 10 times. This proposed method has been successfully applied to the determination of linuron in food samples.

Chen, Jieping; Zhu, Xiashi

2015-02-01

348

3D structure of eukaryotic flagella in a quiescent state revealed by cryo-electron tomography  

PubMed Central

We have used cryo-electron tomography to investigate the 3D structure and macromolecular organization of intact, frozen-hydrated sea urchin sperm flagella in a quiescent state. The tomographic reconstructions provide information at a resolution better than 6 nm about the in situ arrangements of macromolecules that are key for flagellar motility. We have visualized the heptameric rings of the motor domains in the outer dynein arm complex and determined that they lie parallel to the plane that contains the axes of neighboring flagellar microtubules. Both the material associated with the central pair of microtubules and the radial spokes display a plane of symmetry that helps to explain the planar beat pattern of these flagella. Cryo-electron tomography has proven to be a powerful technique for helping us understand the relationships between flagellar structure and function and the design of macromolecular machines in situ. PMID:16246999

Nicastro, Daniela; McIntosh, J. Richard; Baumeister, Wolfgang

2005-01-01

349

Cryo-electron tomography of microtubules assembled in vitro from purified components.  

PubMed

Cryo-electron tomography of vitrified specimens allows visualization of thin biological samples in three-dimensions. This method can be applied to study the interaction of proteins that show disorder and/or bind in a nonregular fashion to microtubules. Here, we describe the protocols we use to observe microtubules assembled in vitro in the presence of XMAP215, a large and flexible protein that binds to discrete sites on the microtubule lattice. Gold particles are added to the mix before vitrification to facilitate image acquisition in low-dose mode and their subsequent alignment before tomographic reconstruction. Three-dimensional reconstructions are performed using the IMOD software, processed with ImageJ and visualized in UCSF Chimera. Extraction of features of interest is performed using a patch-based algorithm (CryoSeg) developed in the laboratory. All the software used in this procedure is freely available or can be obtained on request, and run on most operating systems. PMID:21773930

Coquelle, Frédéric M; Blestel, Sophie; Heichette, Claire; Arnal, Isabelle; Kervrann, Charles; Chrétien, Denis

2011-01-01

350

Using cryo-EM to measure the dipole potential of a lipid membrane  

PubMed Central

The dipole potential of a lipid bilayer membrane accounts for its much larger permeability to anions than cations and affects the conformation and function of membrane proteins. The absolute value of the dipole potential has been very difficult to measure, although its value has been estimated to range from 200 to 1,000 mV from ion translocation rates, the surface potential of lipid monolayers, and molecular dynamics calculations. Here, a point charge probe method was used to investigate the dipole potentials of both ester and ether lipid membranes. The interactions between electrons and lipid molecules were recorded by phase-contrast imaging using cryo-EM. The magnitude and the profile of the dipole potential along the bilayer normal were obtained by subtracting the contribution of the atomic potential from the cryo-EM image intensity. The peak dipole potential was estimated to be 510 and 260 mV for diphytanoylphosphatidylcholine and diphytanylphosphatidylcholine, respectively. PMID:17116859

Wang, Liguo; Bose, Pulkit S.; Sigworth, Fred J.

2006-01-01

351

EMDataBank.org: unified data resource for CryoEM  

PubMed Central

Cryo-electron microscopy reconstruction methods are uniquely able to reveal structures of many important macromolecules and macromolecular complexes. EMDataBank.org, a joint effort of the Protein Data Bank in Europe (PDBe), the Research Collaboratory for Structural Bioinformatics (RCSB) and the National Center for Macromolecular Imaging (NCMI), is a global ‘one-stop shop’ resource for deposition and retrieval of cryoEM maps, models and associated metadata. The resource unifies public access to the two major archives containing EM-based structural data: EM Data Bank (EMDB) and Protein Data Bank (PDB), and facilitates use of EM structural data of macromolecules and macromolecular complexes by the wider scientific community. PMID:20935055

Lawson, Catherine L.; Baker, Matthew L.; Best, Christoph; Bi, Chunxiao; Dougherty, Matthew; Feng, Powei; van Ginkel, Glen; Devkota, Batsal; Lagerstedt, Ingvar; Ludtke, Steven J.; Newman, Richard H.; Oldfield, Tom J.; Rees, Ian; Sahni, Gaurav; Sala, Raul; Velankar, Sameer; Warren, Joe; Westbrook, John D.; Henrick, Kim; Kleywegt, Gerard J.; Berman, Helen M.; Chiu, Wah

2011-01-01

352

Technical assessment of cryo-compressed hydrogen storage tank systems for automotive applications  

Microsoft Academic Search

On-board and off-board performance and cost of cryo-compressed hydrogen storage are assessed and compared to the targets for automotive applications. The on-board performance of the system and high-volume manufacturing cost were determined for liquid hydrogen refueling with a single-flow nozzle and a pump that delivers liquid H2 to the insulated cryogenic tank capable of being pressurized to 272atm. The off-board

R. K. Ahluwalia; T. Q. Hua; J.-K. Peng; S. Lasher; K. McKenney; J. Sinha; M. Gardiner; TIAX LLC

2010-01-01

353

A lumped-parameter model for cryo-adsorber hydrogen storage tank  

Microsoft Academic Search

One of the primary requirements for commercialization of hydrogen fuel-cell vehicles is the on-board storage of hydrogen in sufficient quantities. On-board storage of hydrogen by adsorption on nano-porous adsorbents at around liquid nitrogen temperatures and moderate pressures is considered viable and competitive with other storage technologies: liquid hydrogen, compressed gas, and metallic or complex hydrides. The four cryo-adsorber fuel tank

V. Senthil Kumar; K. Raghunathan; Sudarshan Kumar

2009-01-01

354

Technical assessment of cryo-compressed hydrogen storage tank systems for automotive applications  

Microsoft Academic Search

On-board and off-board performance and cost of cryo-compressed hydrogen storage has been assessed and compared to the DOE 2010, 2015 and ultimate targets for automotive applications. The Gen-3 prototype system of Lawrence Livermore National Laboratory was modeled to project the performance of a scaled-down 5.6-kg usable hydrogen storage system. The on-board performance of the system and high-volume manufacturing cost were

R. K. Ahluwalia; T. Q. Hua; J.-K. Peng; S. Lasher; K. McKenney; J. Sinha; TIAX LLC

2010-01-01

355

Controlling protein adsorption on graphene for cryo-EM using low-energy hydrogen plasmas  

PubMed Central

Despite its many favorable properties as a sample support for biological electron microscopy, graphene is not widely used because its hydrophobicity precludes reliable protein deposition. We describe a method to modify graphene using a low-energy hydrogen plasma, which reduces hydrophobicity without degrading the graphene lattice. We show that the use of plasma-treated graphene enables better control of protein distribution in ice for electron cryo-microscopy and improved image quality by reducing radiation-induced sample motion. PMID:24747813

Russo, Christopher J.; Passmore, Lori A.

2014-01-01

356

CryoLand - GMES Service Snow and Land Ice - Interoperability, Service Integration and User Access  

Microsoft Academic Search

\\u000a The CryoLand project implements and validates a standardized and sustainable service on snow and land ice monitoring as a\\u000a Downstream Service of GMES. It will provide geospatial product coverages of seasonal snow (snow extent, snow mass, melt state),\\u000a glaciers (area, snow \\/ ice extent, ice velocities, glacier dammed lakes), and lake \\/ river ice (extent, temporal variations,\\u000a snow burden) derived

Gerhard Triebnig; Andrei Diamandi; Richard Hall; Eirik Malnes; Lars Marklund; Sari Metsämäki; Thomas Nagler; Jouni Pulliainen; Helmut Rott; Christian Schiller; Rune Solberg; Andreas Wiesmann

357

Comparative study of projection/back-projection schemes in cryo-EM tomography  

NASA Astrophysics Data System (ADS)

In the cryo-EM tomography, the projection and back-projection are essential steps in reconstruction the 3D structure of the virus and macromolecules. Distance driven method (DD) is the latest projection /backprojection algorithm originally employed for x-ray computed tomography. This paper is mainly concerned about employing this algorithm to the cryo-EM tomography for reconstruction performance improvement. Existing algorithms used in cryo-EM are pixel-driven and ray driven projection/backprojection, etc. These methods are generally quite time consuming because of their high computational complexity. Furthermore, interpolation artifacts are usually noticeable when the sufficient view and detector samples are not available. The DD is originally proposed to overcome these drawbacks. The interpolation process in DD is done by calculating the overlap area between the detector and pixel boundaries. This procedure largely removes the interpolation artifacts, and reduces the computational complexity significantly. Furthermore, it guarantees that the projection and backprojection are adjoint to each other - a desired property to guarantee the convergence of the iterative reconstruction algorithm. However, unlike the x-ray computed tomography, the cryo-EM tomography problem generally has limited number of the projections, and projection angles are randomly distributed over 4pi steradian. Therefore, the conventional DD should be modified. Rather than computing the boundary overlap in the previous 3-D DD method, we propose a novel DD algorithm based on volume overlap. CCMV virus model is used as testing example. Results are visualized using AMIRA software. Analysis is made upon the advantages and drawbacks of both the existing approaches and distance driven method.

Liu, Yu; Ye, Jong Chul

2006-08-01

358

Correlative VIS-fluorescence and soft X-ray cryo-microscopy/tomography of adherent cells.  

PubMed

Soft X-ray cryo-microscopy/tomography of vitreous samples is becoming a valuable tool in structural cell biology. Within the 'water-window' wavelength region (2.34-4.37nm), it provides absorption contrast images with high signal to noise ratio and resolution of a few tens of nanometer. Soft X-rays with wavelengths close to the K-absorption edge of oxygen penetrate biological samples with thicknesses in the micrometer range. Here, we report on the application of a recently established extension of the transmission soft X-ray cryo-microscope (HZB TXM) at the beamline U41-XM of the BESSY II electron storage ring by an in-column epi-fluorescence and reflected light cryo-microscope. We demonstrate the new capability for correlative fluorescence and soft X-ray cryo-microscopy/tomography of this instrument along a typical life science experimental approach - the correlation of a fluorophore-tagged protein (pUL34-GFP of pseudorabies virus, PrV, the nuclear membrane-anchored component of the nuclear egress complex of the Herpesviridae which interacts with viral pUL31) in PrV pUL34-GFP/pUL31 coexpressing mammalian cells, with virus-induced vesicular structures in the nucleus, expanding the nucleoplasmic reticulum. Taken together, our results demonstrate new possibilities to study the role of specific proteins in substructures of adherent cells, especially of the nucleus in toto, accessible to electron microscopy in thinned samples only. PMID:22210307

Hagen, Christoph; Guttmann, Peter; Klupp, Barbara; Werner, Stephan; Rehbein, Stefan; Mettenleiter, Thomas C; Schneider, Gerd; Grünewald, Kay

2012-02-01

359

Correlative VIS-fluorescence and soft X-ray cryo-microscopy/tomography of adherent cells  

PubMed Central

Soft X-ray cryo-microscopy/tomography of vitreous samples is becoming a valuable tool in structural cell biology. Within the ‘water-window’ wavelength region (2.34–4.37 nm), it provides absorption contrast images with high signal to noise ratio and resolution of a few tens of nanometer. Soft X-rays with wavelengths close to the K-absorption edge of oxygen penetrate biological samples with thicknesses in the micrometer range. Here, we report on the application of a recently established extension of the transmission soft X-ray cryo-microscope (HZB TXM) at the beamline U41-XM of the BESSY II electron storage ring by an in-column epi-fluorescence and reflected light cryo-microscope. We demonstrate the new capability for correlative fluorescence and soft X-ray cryo-microscopy/tomography of this instrument along a typical life science experimental approach – the correlation of a fluorophore-tagged protein (pUL34-GFP of pseudorabies virus, PrV, the nuclear membrane-anchored component of the nuclear egress complex of the Herpesviridae which interacts with viral pUL31) in PrV pUL34-GFP/pUL31 coexpressing mammalian cells, with virus-induced vesicular structures in the nucleus, expanding the nucleoplasmic reticulum. Taken together, our results demonstrate new possibilities to study the role of specific proteins in substructures of adherent cells, especially of the nucleus in toto, accessible to electron microscopy in thinned samples only. PMID:22210307

Hagen, Christoph; Guttmann, Peter; Klupp, Barbara; Werner, Stephan; Rehbein, Stefan; Mettenleiter, Thomas C.; Schneider, Gerd; Grünewald, Kay

2012-01-01

360

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

NASA Astrophysics Data System (ADS)

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 using a system combining polymer membrane gas separation technology and a Joule-Thomson closed-cycle refrigerator filled with a nitrogen-hydrocarbons gas mixture. Nitrogen is separated from the compressed air, then liquefied and throttled to atmospheric pressure. The paper analyzes the demanded cooling capacity of the system resulting from cryomedical treatment requirements. Thermal design and flow scheme of the apparatus are given. The system is thermodynamically optimized.

Chorowski, M.; Piotrowska, A.; Polinski, J.

2006-04-01

361

Construction and Organization of a BSL-3 Cryo-Electron Microscopy Laboratory at UTMB  

PubMed Central

A unique cryo-electron microscopy facility has been designed and constructed at the University of Texas Medical Branch (UTMB) to study the three-dimensional organization of viruses and bacteria classified as select agents at biological safety level (BSL)-3, and their interactions with host cells. A 200 keV high-end cryo-electron microscope was installed inside a BSL-3 containment laboratory and standard operating procedures were developed and implemented to ensure its safe and efficient operation. We also developed a new microscope decontamination protocol based on chlorine dioxide gas with a continuous flow system, which allowed us to expand the facility capabilities to study bacterial agents including spore-forming species. The new unified protocol does not require agent-specific treatment in contrast to the previously used heat decontamination. To optimize the use of the cryo-electron microscope and to improve safety conditions, it can be remotely controlled from a room outside of containment, or through a computer network world-wide. Automated data collection is provided by using JADAS (single particle imaging) and SerialEM (tomography). The facility has successfully operated for more than a year without an incident and was certified as a select agent facility by the Centers for Disease Control. PMID:23274136

Sherman, Michael B.; Trujillo, Juan; Leahy, Ian; Razmus, Dennis; DeHate, Robert; Lorcheim, Paul; Czarneski, Mark A.; Zimmerman, Domenica; Newton, Je T’Aime M.; Haddow, Andrew D.; Weaver, Scott C.

2013-01-01

362

A blind deconvolution approach for improving the resolution of cryo-EM density maps.  

PubMed

Cryo-electron microscopy (cryo-EM) plays an increasingly prominent role in structure elucidation of macromolecular assemblies. Advances in experimental instrumentation and computational power have spawned numerous cryo-EM studies of large biomolecular complexes resulting in the reconstruction of three-dimensional density maps at intermediate and low resolution. In this resolution range, identification and interpretation of structural elements and modeling of biomolecular structure with atomic detail becomes problematic. In this article, we present a novel algorithm that enhances the resolution of intermediate- and low-resolution density maps. Our underlying assumption is to model the low-resolution density map as a blurred and possibly noise-corrupted version of an unknown high-resolution map that we seek to recover by deconvolution. By exploiting the nonnegativity of both the high-resolution map and blur kernel, we derive multiplicative updates reminiscent of those used in nonnegative matrix factorization. Our framework allows for easy incorporation of additional prior knowledge such as smoothness and sparseness, on both the sharpened density map and the blur kernel. A probabilistic formulation enables us to derive updates for the hyperparameters; therefore, our approach has no parameter that needs adjustment. We apply the algorithm to simulated three-dimensional electron microscopic data. We show that our method provides better resolved density maps when compared with B-factor sharpening, especially in the presence of noise. Moreover, our method can use additional information provided by homologous structures, which helps to improve the resolution even further. PMID:21385038

Hirsch, Michael; Schölkopf, Bernhard; Habeck, Michael

2011-03-01

363

Beam-induced motion correction for sub-megadalton cryo-EM particles.  

PubMed

In electron cryo-microscopy (cryo-EM), the electron beam that is used for imaging also causes the sample to move. This motion blurs the images and limits the resolution attainable by single-particle analysis. In a previous Research article (Bai et al., 2013) we showed that correcting for this motion by processing movies from fast direct-electron detectors allowed structure determination to near-atomic resolution from 35,000 ribosome particles. In this Research advance article, we show that an improved movie processing algorithm is applicable to a much wider range of specimens. The new algorithm estimates straight movement tracks by considering multiple particles that are close to each other in the field of view, and models the fall-off of high-resolution information content by radiation damage in a dose-dependent manner. Application of the new algorithm to four data sets illustrates its potential for significantly improving cryo-EM structures, even for particles that are smaller than 200 kDa. PMID:25122622

Scheres, Sjors Hw

2014-01-01

364

Structure of the mite-transmitted Blackcurrant reversion nepovirus using electron cryo-microscopy  

SciTech Connect

Blackcurrant reversion nepovirus (BRV; genus Nepovirus) has a single-stranded, bipartite RNA genome surrounded by 60 copies of a single capsid protein (CP). BRV is the most important mite-transmitted viral pathogen of the Ribes species. It is the causal agent of blackcurrant reversion disease. We determined the structure of BRV to 1.7 nm resolution using electron cryo- microscopy (cryoEM) and image reconstruction. The reconstruction reveals a pseudo T = 3 viral capsid similar to that of tobacco ringspot virus (TRSV). We modelled the BRV capsid protein to that of TRSV and fitted it into the cryoEM reconstruction. The fit indicated that the extended C-terminus of BRV-CP is located on the capsid surface and the N-terminus on the interior. We generated peptide antibodies to two putatively exposed C-terminal sequences and these reacted with the virus. Hence homology modelling may be useful for defining epitopes for antibody generation for diagnostic testing of BRV in commercial crops.

Seitsonen, Jani J.T. [Institute of Biotechnology, P.O. Box 65 (Viikinkaari 1), FIN-00014 University of Helsinki (Finland); Susi, Petri [Department of Virology, University of Turku (Kiinamyllynkatu 13), FIN-20520 Turku (Finland); Lemmetty, Anne [MTT Agrifood Research Finland, Plant Protection, FIN-31600 Jokioinen (Finland); Butcher, Sarah J. [Institute of Biotechnology, P.O. Box 65 (Viikinkaari 1), FIN-00014 University of Helsinki (Finland)], E-mail: sarah.butcher@helsinki.fi

2008-08-15

365

Effect of cryo-induced microcracks on microindentation of hydrated cortical bone tissue  

SciTech Connect

Microcracks accumulate in cortical bone tissue as a consequence of everyday cyclic loading. However, it remains unclear to what extent microdamage accumulation contributes to an increase in fracture risk. A cryo-preparation technique was applied to induce microcracks in cortical bone tissue. Microcracks with lengths up to approximately 20 {mu}m, which were initiated mainly on the boundaries of haversian canals, were observed with cryo-scanning electron microscopy. A microindentation technique was applied to study the mechanical loading effect on the microcracked hydrated bone tissue. The microindentation patterns were section-scanned using confocal laser scanning microscopy to understand the deformation and bone damage mechanisms made by mechanical loading. The results show that there was no significant difference with respect to microhardness between the original and microcracked hydrated cortical bone tissues (ANOVA, p > 0.05). The cryo-induced microcracks in the bone tissue were not propagated further under the mechanical loads applied. The deformation mechanism of the microcracked cortical bone tissue was plastic deformation, not brittle fracture.

Yin Ling, E-mail: ling.yin@jcu.edu.au [School of Engineering, James Cook University, Townsville, QLD 4811 (Australia); Venkatesan, Sudharshan [Department of Engineering, Australian National University, Canberra, ACT 0200 Australia (Australia); Webb, Daryl [Electron Microscopy Unit, Australian National University, Canberra, ACT 0200 (Australia); Kalyanasundaram, Shankar; Qin Qinghua [Department of Engineering, Australian National University, Canberra, ACT 0200 Australia (Australia)

2009-08-15

366

Correlative microscopy: bridging the gap between fluorescence light microscopy and cryo-electron tomography.  

PubMed

Cryo-electron tomography of frozen-hydrated biological samples offers a means of studying large and complex cellular structures in three-dimensions and with nanometer-scale resolution. The low contrast of unstained biological material embedded in amorphous ice and the need to minimise the exposure of these radiation-sensitive samples to the electron beam result in a poor signal-to-noise ratio. This poses problems not only in the visualisation and interpretation of such tomograms, it is also a problem in surveying the sample and in finding regions which contain the features of interest and which are suitable for recording tomograms. To address this problem, we have developed a correlative fluorescence light microscopy-electron microscopy approach, which guides the search for the structures of interest and allows electron microscopy to zoom in on them. With our approach, the total dose spent on locating regions of interest is negligible. A newly designed cryo-holder allows imaging of fluorescently labelled samples after vitrification. The absolute coordinates of structures identified and located by cryo-light microscopy are transferred to the electron microscope via a Matlab-based user interface. We have successfully tested the experimental setup and the whole procedure with two types of adherent fluorescently labelled cells, a neuronal cell line and keratinocytes, both grown directly on EM grids. PMID:17884579

Sartori, Anna; Gatz, Rudolf; Beck, Florian; Rigort, Alexander; Baumeister, Wolfgang; Plitzko, Juergen M

2007-11-01

367

Beam-induced motion correction for sub-megadalton cryo-EM particles  

PubMed Central

In electron cryo-microscopy (cryo-EM), the electron beam that is used for imaging also causes the sample to move. This motion blurs the images and limits the resolution attainable by single-particle analysis. In a previous Research article (Bai et al., 2013) we showed that correcting for this motion by processing movies from fast direct-electron detectors allowed structure determination to near-atomic resolution from 35,000 ribosome particles. In this Research advance article, we show that an improved movie processing algorithm is applicable to a much wider range of specimens. The new algorithm estimates straight movement tracks by considering multiple particles that are close to each other in the field of view, and models the fall-off of high-resolution information content by radiation damage in a dose-dependent manner. Application of the new algorithm to four data sets illustrates its potential for significantly improving cryo-EM structures, even for particles that are smaller than 200 kDa. DOI: http://dx.doi.org/10.7554/eLife.03665.001 PMID:25122622

Scheres, Sjors HW

2014-01-01

368

CryoSat: ESA'S ice Explorer Mission. 4 years in operations: status and achievements  

NASA Astrophysics Data System (ADS)

CryoSat-2 was launched on the 8th April 2010 and it is the first European ice mission dedicated to monitoring precise changes in the thickness of polar ice sheets and floating sea ice over a 3-year period. CryoSat-2 carries an innovative radar altimeter called the Synthetic Aperture Interferometric Altimeter (SIRAL) with two antennas and with extended capabilities to meet the measurement requirements for ice-sheets elevation and sea-ice freeboard. Initial results have shown that data is of high quality thanks to an altimeter that is behaving exceptional well within its design specifications. The CryoSat mission will reach its 4th years of operational life in April 2014. Since its launch has delivered high quality products to the worldwide cryospheric and marine community that is increasing every year. Scope of this paper is to describe the current mission status and the main scientific achievements in the last twelve months. Topics will also include programmatic highlights and information on the next scientific developments of the mission in its extended period that will be confirmed in autumn 2014.

Parrinello, Tommaso; Mardle, Nic; Hoyos, Berta; Badessi, Stefano; Frommknecht, Bjorn; Bouzinac, Catherine; Davidson, Malcolm; Fornari, Marco; Scagliola, Michele; Cullen, Robert

2014-05-01

369

Magnetism  

NSDL National Science Digital Library

This radio broadcast discusses the history of magnetism from the time of its discovery by an apocryphal Greek sheperd until the late 16th century and the work of William Gilbert. There is also discussion of who pioneered the study of magnetism, what theories they constructed from its curious abilities, and how the power of the magnet was brought out of the realm of magic and into the service of science. The broadcast concludes with a discussion of why magnetism is still mysterious and how the modern search for the single magnetic pole, or magnetic monopole, could provide a fundamental unit of magnetism, essential for ultimate explanation. The broadcast is 41 minutes and 45 seconds in length.

370

Estimation of Arctic Sea Ice Freeboard and Thickness Using CryoSat-2  

NASA Astrophysics Data System (ADS)

Arctic sea ice is one of the significant components of the global climate system as it plays a significant role in driving global ocean circulation, provides a continuous insulating layer at air-sea interface, and reflects a large portion of the incoming solar radiation in Polar Regions. Sea ice extent has constantly declined since 1980s. Its area was the lowest ever recorded on 16 September 2012 since the satellite record began in 1979. Arctic sea ice thickness has also been diminishing along with the decreasing sea ice extent. Because extent and thickness, two main characteristics of sea ice, are important indicators of the polar response to on-going climate change, there has been a great effort to quantify them using various approaches. Sea ice thickness has been measured with numerous field techniques such as surface drilling and deploying buoys. These techniques provide sparse and discontinuous data in spatiotemporal domain. Spaceborne radar and laser altimeters can overcome these limitations and have been used to estimate sea ice thickness. Ice Cloud and land Elevation Satellite (ICEsat), a laser altimeter from National Aeronautics and Space Administration (NASA), provided data to detect polar area elevation change between 2003 and 2009. CryoSat-2 launched with Synthetic Aperture Radar (SAR)/Interferometric Radar Altimeter (SIRAL) on April 2010 can provide data to estimate time-series of Arctic sea ice thickness. In this study, Arctic sea ice freeboard and thickness in 2012 and 2013 were estimated using CryoSat-2 SAR mode data that has sea ice surface height relative to the reference ellipsoid WGS84. In order to estimate sea ice thickness, freeboard height, elevation difference between the top of sea ice surface and leads should be calculated. CryoSat-2 profiles such as pulse peakiness, backscatter sigma-0, number of echoes, and significant wave height were examined to distinguish leads from sea ice. Several near-real time cloud-free MODIS images as CryoSat-2 data were used to identify leads. Rule-based machine learning approaches such as random forest and See5.0 and human-derived decision trees were used to produce rules to identify leads. With the freeboard height calculated from the lead analysis, sea ice thickness was finally estimated using the Archimedes' buoyancy principle with density of sea ice and sea water and the height of freeboard. The results were compared with Arctic sea ice thickness distribution retrieved from CryoSat-2 data by Alfred-Wegener-Institute.

Lee, Sanggyun; Im, Jungho; yoon, Hyeonjin; Shin, Minso; Kim, Miae

2014-05-01

371

Cryo-EM Imaging of DNA-PK DNA Damage Repair Complexes  

SciTech Connect

Exposure to low levels of ionizing radiation causes DNA double-strand breaks (DSBs) that must be repaired for cell survival. Higher eukaryotes respond to DSBs by arresting the cell cycle, presumably to repair the DNA lesions before cell division. In mammalian cells, the nonhomologous end-joining DSB repair pathway is mediated by the 470 kDa DNA-dependent protein kinase catalytic subunit (DNA-PKcs) together with the DNA-binding factors Ku70 and Ku80. Mouse knock-out models of these three proteins are all exquisitely sensitive to low doses of ionizing radiation. In the presence of DNA ends, Ku binds to the DNA and then recruits DNA-PKcs. After formation of the complex, the kinase activity associated with DNA-PKcs becomes activated. This kinase activity has been shown to be essential for repairing DNA DSBs in vivo since expression of a kinase-dead form of DNA-PKcs in a mammalian cell line that lacks DNA-PKcs fails to complement the radiosensitive phenotype. The immense size of DNA-PKcs suggests that it may also serve as a docking site for other DNA repair proteins. Since the assembly of the DNA-PK complex onto DNA is a prerequisite for DSB repair, it is critical to obtain structural information on the complex. Cryo-electron microscopy (cryo-EM) and single particle reconstruction methods provide a powerful way to image large macromolecular assemblies at near atomic (10-15 ?) resolution. We have already used cryo-EM methods to examine the structure of the isolated DNA-PKcs protein. This structure reveals numerous cavities throughout the protein that may allow passage of single or double-stranded DNA. Pseudo two-fold symmetry was found for the monomeric protein, suggesting that DNA-PKcs may interact with two DNA ends or two Ku heterodimers simultaneously. Here we propose to study the structure of the cross-linked DNA-PKcs/Ku/DNA complex. Difference imaging with our published DNA-PKcs structure will enable us to elucidate the architecture of the complex. A second objective is to locate the kinase domain of DNA-PKcs by determining the structure of a kinase deletion mutant both as an isolated protein and as part of a DNA-PKcs/Ku/DNA complex. A third objective is to pursue higher resolution studies of DNA-PKcs and the DNA-PKcs/Ku/DNA complex. If the crystal structure determination of DNA-PKcs is completed during the project period, the atomic coordinates of DNA-PKcs will be modeled within the cryo-EM structure of the complex. In order to achieve these goals, a collaborative effort is proposed between Dr. Phoebe Stewart at UCLA, whose laboratory has expertise in cryo-EM reconstruction methods, and Dr. David Chen at the Lawrence Berkeley National Laboratory, who has a long-standing interest in DNA repair. Advantages of the cryo-EM structural method include the fact that the sample is imaged in a frozen-hydrated and unstained state, avoiding artifacts associated with drying and staining in other EM approaches. Also crystals of the sample are not needed for the single particle reconstruction method and only microgram quantities of sample are required. Cryo-EM structural information of macromolecular assemblies is complementary to both atomic structures of individual component molecules, as well as low resolution information obtained from x-ray and neutron scattering. Knowledge of the geometrical arrangement of the complex, and the position of the essential DNA-PKcs kinase domain, should lead to a greater understanding of the molecular events in DNA double-strand break repair following exposure to low doses of radiation.

Phoebe L. Stewart

2005-06-27

372

Ultracapacitor separator  

DOEpatents

An ultracapacitor includes two solid, nonporous current collectors, two porous electrodes separating the collectors, a porous separator between the electrodes and an electrolyte occupying the pores in the electrodes and separator. The electrolyte is a polar aprotic organic solvent and a salt. The porous separator comprises a wet laid cellulosic material.

Wei, Chang (Niskayuna, NY); Jerabek, Elihu Calvin (Glenmont, NY); LeBlanc, Jr., Oliver Harris (Schenectady, NY)

2001-03-06

373

Size-regulated group separation of CoFe2O4 nanoparticles using centrifuge and their magnetic resonance contrast properties  

PubMed Central

Magnetic nanoparticle (MNP)-based magnetic resonance imaging (MRI) contrast agents (CAs) have been the subject of extensive research over recent decades. The particle size of MNPs varies widely and is known to influence their physicochemical and pharmacokinetic properties. There are two commonly used methods for synthesizing MNPs, organometallic and aqueous solution coprecipitation. The former has the advantage of being able to control the particle size more effectively; however, the resulting particles require a hydrophilic coating in order to be rendered water soluble. The MNPs produced using the latter method are intrinsically water soluble, but they have a relatively wide particle size distribution. Size-controlled water-soluble MNPs have great potential as MRI CAs and in cell sorting and labeling applications. In the present study, we synthesized CoFe2O4 MNPs using an aqueous solution coprecipitation method. The MNPs were subsequently separated into four groups depending on size, by the use of centrifugation at different speeds. The crystal shapes and size distributions of the particles in the four groups were measured and confirmed by transmission electron microscopy and dynamic light scattering. Using X-ray diffraction analysis, the MNPs were found to have an inverse spinel structure. Four MNP groups with well-selected semi-Gaussian-like diameter distributions were obtained, with measured T2 relaxivities (r2) at 4.7 T and room temperature in the range of 60 to 300 mM?1s?1, depending on the particle size. This size regulation method has great promise for applications that require homogeneous-sized MNPs made by an aqueous solution coprecipitation method. Any group of the CoFe2O4 MNPs could be used as initial base cores of MRI T2 CAs, with almost unique T2 relaxivity owing to size regulation. The methodology reported here opens up many possibilities for biosensing applications and disease diagnosis. PACS 75.75.Fk, 78.67.Bf, 61.46.Df PMID:24004536

2013-01-01

374

Size-regulated group separation of CoFe2O4 nanoparticles using centrifuge and their magnetic resonance contrast properties.  

PubMed

Magnetic nanoparticle (MNP)-based magnetic resonance imaging (MRI) contrast agents (CAs) have been the subject of extensive research over recent decades. The particle size of MNPs varies widely and is known to influence their physicochemical and pharmacokinetic properties. There are two commonly used methods for synthesizing MNPs, organometallic and aqueous solution coprecipitation. The former has the advantage of being able to control the particle size more effectively; however, the resulting particles require a hydrophilic coating in order to be rendered water soluble. The MNPs produced using the latter method are intrinsically water soluble, but they have a relatively wide particle size distribution. Size-controlled water-soluble MNPs have great potential as MRI CAs and in cell sorting and labeling applications. In the present study, we synthesized CoFe2O4 MNPs using an aqueous solution coprecipitation method. The MNPs were subsequently separated into four groups depending on size, by the use of centrifugation at different speeds. The crystal shapes and size distributions of the particles in the four groups were measured and confirmed by transmission electron microscopy and dynamic light scattering. Using X-ray diffraction analysis, the MNPs were found to have an inverse spinel structure. Four MNP groups with well-selected semi-Gaussian-like diameter distributions were obtained, with measured T2 relaxivities (r2) at 4.7 T and room temperature in the range of 60 to 300 mM-1s-1, depending on the particle size. This size regulation method has great promise for applications that require homogeneous-sized MNPs made by an aqueous solution coprecipitation method. Any group of the CoFe2O4 MNPs could be used as initial base cores of MRI T2 CAs, with almost unique T2 relaxivity owing to size regulation. The methodology reported here opens up many possibilities for biosensing applications and disease diagnosis. PACS: 75.75.Fk, 78.67.Bf, 61.46.Df. PMID:24004536

Kang, Jongeun; Lee, Hyunseung; Kim, Young-Nam; Yeom, Areum; Jeong, Heejeong; Lim, Yong Taik; Hong, Kwan Soo

2013-01-01

375

Size-regulated group separation of CoFe2O4 nanoparticles using centrifuge and their magnetic resonance contrast properties  

NASA Astrophysics Data System (ADS)

Magnetic nanoparticle (MNP)-based magnetic resonance imaging (MRI) contrast agents (CAs) have been the subject of extensive research over recent decades. The particle size of MNPs varies widely and is known to influence their physicochemical and pharmacokinetic properties. There are two commonly used methods for synthesizing MNPs, organometallic and aqueous solution coprecipitation. The former has the advantage of being able to control the particle size more effectively; however, the resulting particles require a hydrophilic coating in order to be rendered water soluble. The MNPs produced using the latter method are intrinsically water soluble, but they have a relatively wide particle size distribution. Size-controlled water-soluble MNPs have great potential as MRI CAs and in cell sorting and labeling applications. In the present study, we synthesized CoFe2O4 MNPs using an aqueous solution coprecipitation method. The MNPs were subsequently separated into four groups depending on size, by the use of centrifugation at different speeds. The crystal shapes and size distributions of the particles in the four groups were measured and confirmed by transmission electron microscopy and dynamic light scattering. Using X-ray diffraction analysis, the MNPs were found to have an inverse spinel structure. Four MNP groups with well-selected semi-Gaussian-like diameter distributions were obtained, with measured T2 relaxivities ( r 2) at 4.7 T and room temperature in the range of 60 to 300 mM-1s-1, depending on the particle size. This size regulation method has great promise for applications that require homogeneous-sized MNPs made by an aqueous solution coprecipitation method. Any group of the CoFe2O4 MNPs could be used as initial base cores of MRI T2 CAs, with almost unique T2 relaxivity owing to size regulation. The methodology reported here opens up many possibilities for biosensing applications and disease diagnosis.

Kang, Jongeun; Lee, Hyunseung; Kim, Young-Nam; Yeom, Areum; Jeong, Heejeong; Lim, Yong Taik; Hong, Kwan Soo

2013-09-01

376

Novel ultra-cryo milling and co-grinding technique in liquid nitrogen to produce dissolution-enhanced nanoparticles for poorly water-soluble drugs.  

PubMed

A novel ultra-cryo milling micronization technique for pharmaceutical powders using liquid nitrogen (LN2 milling) was used to grind phenytoin, a poorly water-soluble drug, to improve its dissolution rate. LN2 milling produced particles that were much finer and more uniform in size and shape than particles produced by jet milling. However, the dissolution rate of LN2-milled phenytoin was the same as that of unground phenytoin due to agglomeration of the submicron particles. To overcome this, phenytoin was co-ground with polyvinylpyrrolidone (PVP). The dissolution rate of co-ground phenytoin was much higher than that of original phenytoin, single-ground phenytoin, a physical mixture of phenytoin and PVP, or jet-milled phenytoin. X-Ray diffraction showed that the crystalline state of mixtures co-ground by LN2 milling remained unchanged. The equivalent improvement in dissolution, whether phenytoin was co-ground or separately ground and then mixed with PVP, suggested that even when co-ground, the grinding of PVP and phenytoin occurs essentially independently. Mixing original PVP with ground phenytoin provided a slight improvement in dissolution, indicating that the particle size of PVP is important for improving dissolution. When mixed with ground phenytoin, PVP ground by LN2 milling aided the wettability and dispersion of phenytoin, enhancing utilization of the large surface area of ground phenytoin. Co-grinding phenytoin with other excipients such as Eudragit L100, hypromellose, hypromellose acetate-succinate, microcrystalline cellulose, hydroxypropylcellulose and carboxymethyl cellulose also improved the dissolution profile, indicating an ultra-cryo milling and co-grinding technique in liquid nitrogen has a broad applicability of the dissolution enhancement of phenytoin. PMID:22382412

Sugimoto, Shohei; Niwa, Toshiyuki; Nakanishi, Yasuo; Danjo, Kazumi

2012-01-01

377

Topical Adapalene in the Treatment of Plantar Warts; Randomized Comparative Open Trial in Comparison with Cryo-Therapy  

PubMed Central

Background: Various therapeutic modalities, which are available for treating plantar wart, have not been successful every time. Aims: To evaluate topical adapalene under occlusion in the treatment of plantar warts and compare it with cryo-therapy. Materials and Methods: 50 patients with 424 plantar warts were included in this single center, two arm, prospective, randomized, control, open study. Patients were allocated randomly into two groups consisting of 25 patients each. Group A patients having 299 plantar warts were treated using adapalene gel 0.1% under occlusion while Group B patients having 125 warts were treated using cryo-therapy. All the patients were evaluated weekly till the clearance of all the warts and the results compared. Result: All the warts of 25 patients of Group A that were treated using adapalene gel 0.1% cleared in 36.71 ± 19.24 (55.95-17.47) days except those in one patient. In Group B, warts in all except one treated by cryo-therapy cleared in 52.17 ± 30.06 (82.23-22.11) days. There were no side effects like scar formation, irritation, erythema, or infections with adapalene group while in the cryo group scar was seen in 2 patients, pain in 24, erythema in 10, and infection in 3 patients. Conclusion: Adapalene gel 0.1% under occlusion is an effective, safe and easy to use treatment for plantar warts and may help clear lesions faster than cryo-therapy.

Gupta, Ramji; Gupta, Sarthak

2015-01-01

378

Elevated Temperature Compressive Strength Properties of Oxide Dispersion Strengthened NiAl After Cryo-milling and Roasting in Nitrogen  

NASA Technical Reports Server (NTRS)

In an effort to superimpose two different elevated temperature strengthening mechanisms in NiAl, several lots of oxide dispersion strengthened (ODS) NiAl powder have been cryo-milled in liquid nitrogen to introduce AlN particles at the grain boundaries. As an alternative to cryo-milling, one lot of ODS NiAl was roasted in nitrogen to produce AlN. Both techniques resulted in hot extruded AlN-strengthened, ODS NiAl alloys which were stronger than the base ODS NiAl between 1200 and 1400 K. However, neither the cryo-milled nor the N2-roasted ODS NiAl alloys were as strong as cryo-milled binary NiAl containing like amounts of AlN. The reason(s) for the relative weakness of cryo-milled ODS NiAl is not certain; however the lack of superior strength in N2-roasted ODS NiAl is probably due to its relatively large AlN particles.

Whittenberger, J. Daniel; Grahle, Peter; Arzt, Eduard; Hebsur, Mohan

1998-01-01

379

Adsorption behavior of poly(dimethyl-diallylammonium chloride) on pulp fiber studied by cryo-time-of-flight secondary ion mass spectrometry and cryo-scanning electron microscopy  

NASA Astrophysics Data System (ADS)

In this study, the adsorption behavior of poly(dimethyl-diallylammonium chloride) (PDADMAC), a retention agent used in papermaking, in a dual polymer system with anionic poly(acrylamide) (A-PAM) was investigated by time-of-flight secondary ion mass spectrometry (TOF-SIMS). Initially, fragment structures and cleavage patterns were identified via TOF-SIMS experiments with deuterium-labeled PDADMAC and the unlabeled analogue. Visualization of PDADMAC on a dry handsheet surface using traditional TOF-SIMS analysis indicated that the electrostatic interaction between coagulated PDADMAC and A-PAM was relatively weak. A novel cryo-TOF-SIMS/SEM system enabled the evaluation of a wet handsheet containing PDADMAC. Analysis of this sample indicated that PDADMAC adsorbs onto the fiber surface and collects preferentially on the tangled fibrils located between fibers.

Masumi, Takashi; Matsushita, Yasuyuki; Aoki, Dan; Takama, Ruka; Saito, Kaori; Kuroda, Katsushi; Fukushima, Kazuhiko

2014-01-01

380

Three-Dimensional cryoEM Reconstruction of Native LDL Particles to 16Å Resolution at Physiological Body Temperature  

PubMed Central

Background Low-density lipoprotein (LDL) particles, the major carriers of cholesterol in the human circulation, have a key role in cholesterol physiology and in the development of atherosclerosis. The most prominent structural components in LDL are the core-forming cholesteryl esters (CE) and the particle-encircling single copy of a huge, non-exchangeable protein, the apolipoprotein B-100 (apoB-100). The shape of native LDL particles and the conformation of native apoB-100 on the particles remain incompletely characterized at the physiological human body temperature (37°C). Methodology/Principal Findings To study native LDL particles, we applied cryo-electron microscopy to calculate 3D reconstructions of LDL particles in their hydrated state. Images of the particles vitrified at 6°C and 37°C resulted in reconstructions at ?16 Å resolution at both temperatures. 3D variance map analysis revealed rigid and flexible domains of lipids and apoB-100 at both temperatures. The reconstructions showed less variability at 6°C than at 37°C, which reflected increased order of the core CE molecules, rather than decreased mobility of the apoB-100. Compact molecular packing of the core and order in a lipid-binding domain of apoB-100 were observed at 6°C, but not at 37°C. At 37°C we were able to highlight features in the LDL particles that are not clearly separable in 3D maps at 6°C. Segmentation of apoB-100 density, fitting of lipovitellin X-ray structure, and antibody mapping, jointly revealed the approximate locations of the individual domains of apoB-100 on the surface of native LDL particles. Conclusions/Significance Our study provides molecular background for further understanding of the link between structure and function of native LDL particles at physiological body temperature. PMID:21573056

Kumar, Vibhor; Butcher, Sarah J.; Öörni, Katariina; Engelhardt, Peter; Heikkonen, Jukka; Kaski, Kimmo; Ala-Korpela, Mika; Kovanen, Petri T.

2011-01-01

381

Development in processing of MgB2 cryo-magnet superconductors  

NASA Astrophysics Data System (ADS)

Spark Plasma Sintering is a promising rapid consolidation technique that allows a better understanding and manipulating of sintering kinetics and therefore makes it possible to obtain MgB2-based ceramics with tailored microstructures. Commercial MgB2 powders were spark plasma sintered with an applied mechanical pressure, leading to MgB2 pellets with 99% relative density. The obtained samples show a sharp superconducting transition with an onset at 38.5 K. The critical current density was measured equal to 5.6 × 104 A/cm2 at 20 K under 1 T applied field. Otherwise, the trapped field was also investigated. A 5 mm thick pellet with a 20 mm diameter prepared with optimized processing temperature demonstrated a trapped field of 1.2 T at 15 K and up to 2.5 T at 10 K.

Noudem, J. G.; Aburras, M.; Bernstein, P.; Chaud, X.; Muralidhar, M.; Murakami, M.

2014-10-01

382

Magnetism  

NSDL National Science Digital Library

This overview of magnetism provides a brief history prior to 1600 and continues with the work of William Gilbert, Hans Christian Oersted, and Andre-Marie Ampere in describing and exploring the magnetosphere and learning the role that electric current plays in producing magnetism. Magnetic field lines are then discussed, citing the work of Michael Faraday. The work of James Clerk Maxwell and Heinrich Hertz is mentioned in a discussion of the relationship of light waves and radio waves as part of the electromagnetic spectrum.

Stern, David

383

Molecular Expressions: Color Separation  

NSDL National Science Digital Library

This item is an interactive Java simulation for introductory physics students on the topic of color. It explores how individual subtractive primary colors can be separated from a full-color photograph and then be reassembled to create the original scene. The mouse cursor may be used to superimpose color separations over one another. As additional separations are added, the resulting image exhibits the realism of a color photograph. This item is part of a larger collection of materials on optics and microscopy developed by the National High Magnetic Field Laboratory and Florida State University.

Davidson, Michael; Parry-Hill, Matthew J.; Sutter, Robert

2008-08-21

384

Electron Cryo-Microscopy Studies of Helminthosporium victoriae Virus 190S Sarah E. Dunn*, Hua Li**, Max L. Nibert***, Said A. Ghabrial**, and Timothy S. Baker*,****  

E-print Network

to estimate the defocus of each micrograph and all other image processing and reconstruction steps were, which include humans, livestock, fungi, agricultural crops, as well as many others [1]. Viruses of electron cryo-microscopy (cryoEM) and 3D image reconstruction to examine the native structure of three

Baker, Timothy S.

385

Structure of a Conserved Retroviral RNA Packaging Element by NMR Spectroscopy and Cryo-Electron Tomography  

PubMed Central

The 5?-untranslated regions (5?-UTRs) of all gammaretroviruses contain a conserved “double hairpin motif” (?CD) that is required for genome packaging. Both hairpins (SL-C and SL-D) contain GACG tetraloops that, in isolated RNAs, are capable of forming “kissing” interactions stabilized by two intermolecular G-C base pairs. We have determined the three-dimensional structure of the double hairpin from the Moloney Murine Leukemia Virus (MoMuLV) ([?CD]2, 132-nucleotides, 42.8 kDaltons) using a 2H-edited NMR spectroscopy-based approach. This approach enabled the detection of 1H-1H dipolar interactions that were not observed in previous studies of isolated SL-C and SL-D hairpin RNAs using traditional 1H-1H correlated and 1H-13C-edited NMR methods. The hairpins participate in intermolecular cross-kissing interactions (SL-C to SL-D’ and SLC’ to SL-D), and stack in an end-to-end manner (SL-C to SL-D and SL-C’ to SL-D’) that gives rise to an elongated overall shape (ca. 95 Å by 45 Å by 25 Å). The global structure was confirmed by cryo-electron tomography (cryo-ET), making [?CD]2 simultaneously the smallest RNA to be structurally characterized to date by cryo-ET and among the largest to be determined by NMR. Our findings suggest that, in addition to promoting dimerization, [?CD]2 functions as a scaffold that helps initiate virus assembly by exposing a cluster of conserved UCUG elements for binding to the cognate nucleocapsid domains of assembling viral Gag proteins. PMID:20933521

Miyazaki, Yasuyuki; Irobalieva, Rossitza N.; Tolbert, Blanton; Smalls-Mantey, Adjoa; Iyalla, Kilali; Loeliger, Kelsey; D’Souza, Victoria; Khant, Htet; Schmid, Michael F.; Garcia, Eric; Telesnitsky, Alice; Chiu, Wah; Summers, Michael F.

2010-01-01

386

Atomic Model of Rabbit Hemorrhagic Disease Virus by Cryo-Electron Microscopy and Crystallography  

PubMed Central

Rabbit hemorrhagic disease, first described in China in 1984, causes hemorrhagic necrosis of the liver. Its etiological agent, rabbit hemorrhagic disease virus (RHDV), belongs to the Lagovirus genus in the family Caliciviridae. The detailed molecular structure of any lagovirus capsid has yet to be determined. Here, we report a cryo-electron microscopic (cryoEM) reconstruction of wild-type RHDV at 6.5 Å resolution and the crystal structures of the shell (S) and protruding (P) domains of its major capsid protein, VP60, each at 2.0 Å resolution. From these data we built a complete atomic model of the RHDV capsid. VP60 has a conserved S domain and a specific P2 sub-domain that differs from those found in other caliciviruses. As seen in the shell portion of the RHDV cryoEM map, which was resolved to ?5.5 Å, the N-terminal arm domain of VP60 folds back onto its cognate S domain. Sequence alignments of VP60 from six groups of RHDV isolates revealed seven regions of high variation that could be mapped onto the surface of the P2 sub-domain and suggested three putative pockets might be responsible for binding to histo-blood group antigens. A flexible loop in one of these regions was shown to interact with rabbit tissue cells and contains an important epitope for anti-RHDV antibody production. Our study provides a reliable, pseudo-atomic model of a Lagovirus and suggests a new candidate for an efficient vaccine that can be used to protect rabbits from RHDV infection. PMID:23341770

Gao, Bingquan; Liu, Yanxin; Zhai, Yujia; Ma, Jun; Zhang, Kai; Baker, Timothy S.; Schulten, Klaus; Zheng, Dong; Pang, Hai; Sun, Fei

2013-01-01

387

Visualization of the herpes simplex virus portal in situ by cryo-electron tomography  

SciTech Connect

Herpes simplex virus type 1 (HSV-1), the prototypical herpesvirus, has an icosahedral nucleocapsid surrounded by a proteinaceous tegument and a lipoprotein envelope. As in tailed bacteriophages, the icosahedral symmetry of the capsid is broken at one of the 12 vertices, which is occupied by a dodecameric ring of portal protein, UL6, instead of a pentamer of the capsid protein, UL19. The portal ring serves as a conduit for DNA entering and exiting the capsid. From a cryo-EM reconstruction of capsids immuno-gold-labeled with anti-UL6 antibodies, we confirmed that UL6 resides at a vertex. To visualize the portal in the context of the assembled capsid, we used cryo-electron tomography to determine the three-dimensional structures of individual A-capsids (empty, mature capsids). The similarity in size and overall shape of the portal and a UL19 pentamer - both are cylinders of {approx} 800 kDa - combined with residual noise in the tomograms, prevented us from identifying the portal vertices directly; however, this was accomplished by a computational classification procedure. Averaging the portal-containing subtomograms produced a structure that tallies with the isolated portal, as previously reconstructed by cryo-EM. The portal is mounted on the outer surface of the capsid floor layer, with its narrow end pointing outwards. This disposition differs from that of known phage portals in that the bulk of its mass lies outside, not inside, the floor. This distinction may be indicative of divergence at the level of portal-related functions other than its role as a DNA channel.

Cardone, Giovanni [Laboratory of Structural Biology Research, National Institute of Arthritis and Musculoskeletal and Skin Diseases, Building 50, Rm 1517, MSC 8025, 50 South Drive, National Institutes of Health, Bethesda, MD 20892-8025 (United States); Winkler, Dennis C. [Laboratory of Structural Biology Research, National Institute of Arthritis and Musculoskeletal and Skin Diseases, Building 50, Rm 1517, MSC 8025, 50 South Drive, National Institutes of Health, Bethesda, MD 20892-8025 (United States); Trus, Benes L. [Laboratory of Structural Biology Research, National Institute of Arthritis and Musculoskeletal and Skin Diseases, Building 50, Rm 1517, MSC 8025, 50 South Drive, National Institutes of Health, Bethesda, MD 20892-8025 (United States); Imaging Sciences Laboratory, Division of Computational Bioscience, Center for Information Technology, National Institutes of Health, Bethesda, MD 20892 (United States); Cheng, Naiqian [Laboratory of Structural Biology Research, National Institute of Arthritis and Musculoskeletal and Skin Diseases, Building 50, Rm 1517, MSC 8025, 50 South Drive, National Institutes of Health, Bethesda, MD 20892-8025 (United States); Heuser, John E. [Department of Cell Biology, Washington University School of Medicine, St. Louis, MO 63110 (United States); Newcomb, William W. [Department of Microbiology and Cancer Center, University of Virginia Health System, Charlottesville, VA 22908 (United States); Brown, Jay C. [Department of Microbiology and Cancer Center, University of Virginia Health System, Charlottesville, VA 22908 (United States); Steven, Alasdair C. [Laboratory of Structural Biology Research, National Institute of Arthritis and Musculoskeletal and Skin Diseases, Building 50, Rm 1517, MSC 8025, 50 South Drive, National Institutes of Health, Bethesda, MD 20892-8025 (United States)]. E-mail: Alasdair_Steven@nih.gov

2007-05-10

388

Structure of a conserved retroviral RNA packaging element by NMR spectroscopy and cryo-electron tomography.  

PubMed

The 5'-untranslated regions of all gammaretroviruses contain a conserved "double-hairpin motif" (?(CD)) that is required for genome packaging. Both hairpins (SL-C and SL-D) contain GACG tetraloops that, in isolated RNAs, are capable of forming "kissing" interactions stabilized by two intermolecular G-C base pairs. We have determined the three-dimensional structure of the double hairpin from the Moloney murine leukemia virus ([?(CD)](2), 132 nt, 42.8 kDa) using a (2)H-edited NMR-spectroscopy-based approach. This approach enabled the detection of (1)H-(1)H dipolar interactions that were not observed in previous studies of isolated SL-C and SL-D hairpin RNAs using traditional (1)H-(1)H correlated and (1)H-(13)C-edited NMR methods. The hairpins participate in intermolecular cross-kissing interactions (SL-C to SL-D' and SLC' to SL-D) and stack in an end-to-end manner (SL-C to SL-D and SL-C' to SL-D') that gives rise to an elongated overall shape (ca 95 Å×45 Å×25 Å). The global structure was confirmed by cryo-electron tomography (cryo-ET), making [?(CD)](2) simultaneously the smallest RNA to be structurally characterized to date by cryo-ET and among the largest to be determined by NMR. Our findings suggest that, in addition to promoting dimerization, [?(CD)](2) functions as a scaffold that helps initiate virus assembly by exposing a cluster of conserved UCUG elements for binding to the cognate nucleocapsid domains of assembling viral Gag proteins. PMID:20933521

Miyazaki, Yasuyuki; Irobalieva, Rossitza N; Tolbert, Blanton S; Smalls-Mantey, Adjoa; Iyalla, Kilali; Loeliger, Kelsey; D'Souza, Victoria; Khant, Htet; Schmid, Michael F; Garcia, Eric L; Telesnitsky, Alice; Chiu, Wah; Summers, Michael F

2010-12-17

389

A versatile cryo-focussing flow switching gas chromatography inlet for trace analysis of intractable compounds.  

PubMed

A wide variety of samples that can be analysed by gas chromatography do not lend themselves to the usual preparation of solvent extracts for split-splitless injections, and are best handled by purge and trap or equilibrium headspace sampling. A cryo-focussing, flow switching gas chromatography inlet system that handles different types of sample without the need for hardware changes has been prototyped. It provides excellent repeatability and linearity with liquid injections, purge and trap, and equilibrium headspace samples, in both split and splitless modes. The performance of the system was tested with sub-nanogram quantities of challenging analytes such as free carboxylic acids, alcohols, diols, phenols and aldehydes, and volatiles purged from contaminated soil, mammal faeces, a pesticide formulation, and a spice. Repeatability RSDs for peak areas were consistently below 11% and repeatabilities of retention times below 0.05%, independently of sample type (liquid or gas phase) and nature or quantity of compound. Regression coefficients of peak areas vs. quantity were typically ? 0.999 over two orders of magnitude ranges extending down to below 0.01 ng, also independently of sample and analyte. Limits of quantitation were robustly below 0.1-0.2 ng. Peak shapes and resolution are the same with use of the cryo-trap and flow switch as they are with conventional injections. Performance is robust to flow rate and, for most compounds, to trapping and desorption temperature. The cryo-trapping flow switching inlet's performance parameters match those of other sample introduction systems, and are achieved with sub-nanogram quantities of intractable analytes. PMID:22920301

Apps, Peter; Mmualefe, Lesego

2012-09-28

390

Improving the Arctic Mean Sea Surface with CryoSat-2 Data  

NASA Astrophysics Data System (ADS)

A fundamental basis for estimating short and long-term changes in the sea surface is a reliable mean sea surface (MSS). Existing MSS models, derived from satellite radar altimetry, generally lack observations above 82 degrees latitude making high Arctic sea surface change estimates unreliable. Most current MSS models use ICESat data, geoid models, ocean circulation models, or a combination of these to extrapolate the MSS above 82 degrees latitude. This approach makes the MSS models unsuited for deriving sea surface anomalies from short-term observations like airborne campaigns (e.g. operation IceBridge). The new state of the art DTU13MSS is a global high-resolution MSS that includes retracked CryoSat-2 data and thereby extends the polar data coverage up to 88 degrees latitude. Furthermore, in the sea-ice covered areas, the SAR and SARin feature of the altimeter on-board CryoSat-2 increases the amount of useable observations dramatically compared to conventional altimeters like ENVISAT and ERS-1/2. Finally the continuous time-series, below 82 degrees latitude, has been extended to cover more than 20 years compared to the 17 years use for the DTU10MSS model. A comparison between DTU13MSS and DTU10MSS show an improvement of more than 20 cm between 82 and 88 degrees latitude. For the first time the three years of retracked CryoSat-2 data will, in combination with DTU13MSS, allow reliable estimation of the trend and annual variations in the high Arctic Ocean sea surface height.

Stenseng, L.; Andersen, O. B.

2013-12-01

391

Gas-assisted annular microsprayer for sample preparation for time-resolved cryo-electron microscopy  

NASA Astrophysics Data System (ADS)

Time-resolved cryo-electron microscopy (TRCEM) has emerged as a powerful technique for transient structural characterization of isolated biomacromolecular complexes in their native state within the time scale of seconds to milliseconds. For TRCEM sample preparation, a microfluidic device has been demonstrated to be a promising approach to facilitate TRCEM biological sample preparation. It is capable of achieving rapidly aqueous sample mixing, controlled reaction incubation, and sample deposition on electron microscopy (EM) grids for rapid freezing. One of the critical challenges is to transfer samples to cryo-EM grids from the microfluidic device. By using a microspraying method, the generated droplet size needs to be controlled to facilitate thin ice film formation on the grid surface for efficient data collection, whilst not being so thin that it dries out before freezing, i.e. an optimized mean droplet size needs to be achieved. In this work, we developed a novel monolithic three dimensional (3D) annular gas-assisted microfluidic sprayer using 3D MEMS (MicroElectroMechanical System) fabrication techniques. The microsprayer demonstrated dense and consistent microsprays with average droplet size between 6 and 9??m, which fulfilled the droplet size requirement for TRCEM sample preparation. With droplet density of around 12–18 per grid window (window size 58? × ?58??m), and a data collectible thin ice region of >50% total wetted area, we collected ~800–1000 high quality CCD micrographs in a 6–8?h period of continuous effort. This level of output is comparable to what were routinely achieving using cryo-grids prepared by conventional blotting and manual data collection. In this case, weeks of data collection with the previous device has been shortened to a day or two. And hundreds of microliters of valuable sample consumption can be reduced to only a small fraction.

Lu, Zonghuan; Barnard, David; Shaikh, Tanvir R.; Meng, Xing; Mannella, Carmen A.; Yassin, Aymen S.; Agrawal, Rajendra K.; Wagenknecht, Terence; Lu, Toh-Ming

2014-11-01

392

Tomographic imaging of biological specimens with the cryo transmission X-ray microscope  

NASA Astrophysics Data System (ADS)

Using the photoelectric absorption contrast between water and protein at 2.4 nm wavelength, cryo X-ray microscopy has visualized protein structures down to 30 nm size in unstained, unsectioned biological specimens. Due to the large depth of focus of the Fresnel zone plate objectives, computed tomography based on a tilt series of X-ray microscopic images can be used to reconstruct the three-dimensional specimen structure. This method has been applied to the green alga Chlamydomonas reinhardtii, and to cell nuclei of male Drosophila melanogaster fruit fly cells.

Weiß, D.; Schneider, G.; Vogt, S.; Guttmann, P.; Niemann, B.; Rudolph, D.; Schmahl, G.

2001-07-01

393

Elevation and elevation change of Greenland and Antarctica derived from CryoSat-2  

NASA Astrophysics Data System (ADS)

The ESA satellite CryoSat-2 has been observing Earth's polar regions since April 2010. It carries a sophisticated radar altimeter and aims for the detection of changes in sea ice thickness as well as surface elevation changes of Earth's land and marine ice sheets. This study focuses on the Greenland and Antarctic ice sheets, considering the contemporary elevation of their surfaces. Based on 2 years of CryoSat-2 data acquisition, elevation change maps and mass balance estimates are presented. Additionally, new digital elevation models (DEMs) and the corresponding error maps are derived. Due to the high orbit of CryoSat-2 (88° N/S) and the narrow across-track spacing, more than 99% of Antarctica's surface area is covered. In contrast, previous radar altimeter measurements of ERS1/2 and ENVISAT were limited to latitudes between 81.5° N and 81.5° S and to surface slopes below 1°. The derived DEMs for Greenland and Antarctica have an accuracy which is similar to previous DEMs obtained by satellite-based laser and radar altimetry (Liu et al., 2001; Bamber et al., 2009, 2013; Fretwell et al., 2013; Howat et al., 2014). Comparisons with ICESat data show that 80% of the CryoSat-2 DEMs have an error of less than 3 m ± 30 m. For both ice sheets the surface elevation change rates between 2011 and 2012 are presented at a resolution of 1 km. Negative elevation changes are concentrated at the west and south-east coast of Greenland and in the Amundsen Sea embayment in West Antarctica (e.g. Pine Island and Thwaites glaciers). They agree well with the dynamic mass loss observed by ICESat between 2003 and 2008 (Pritchard et al., 2009). Thickening occurs along the main trunk of Kamb Ice Stream and in Dronning Maud Land. While the former is a consequence of an ice stream stagnated ∼150 years ago (Rose, 1979; Retzlaff and Bentley, 1993), the latter represents a known large-scale accumulation event (Lenaerts et al., 2013). This anomaly partly compensates for the observed increased volume loss in West Antarctica. In Greenland the findings reveal an increased volume loss of a factor of 2 compared to the period 2003 to 2008. The combined volume loss of Greenland and Antarctica for the period 2011 and 2012 is estimated to be -448 ± 122 km3 yr-1.

Helm, V.; Humbert, A.; Miller, H.

2014-03-01

394

Radiation damage in single-particle cryo-electron microscopy: effects of dose and dose rate  

PubMed Central

Radiation damage is an important resolution limiting factor both in macromolecular X-ray crystallography and cryo-electron microscopy. Systematic studies in macromolecular X-ray crystallography greatly benefited from the use of dose, expressed as energy deposited per mass unit, which is derived from parameters including incident flux, beam energy, beam size, sample composition and sample size. In here, the use of dose is reintroduced for electron microscopy, accounting for the electron energy, incident flux and measured sample thickness and composition. Knowledge of the amount of energy deposited allowed us to compare doses with experimental limits in macromolecular X-ray crystallography, to obtain an upper estimate of radical concentrations that build up in the vitreous sample, and to translate heat-transfer simulations carried out for macromolecular X-ray crystallography to cryo-electron microscopy. Stroboscopic exposure series of 50–250 images were collected for different incident flux densities and integration times from Lumbricus terrestris extracellular hemoglobin. The images within each series were computationally aligned and analyzed with similarity metrics such as Fourier ring correlation, Fourier ring phase residual and figure of merit. Prior to gas bubble formation, the images become linearly brighter with dose, at a rate of approximately 0.1% per 10?MGy. The gradual decomposition of a vitrified hemoglobin sample could be visualized at a series of doses up to 5500?MGy, by which dose the sample was sublimed. Comparison of equal-dose series collected with different incident flux densities showed a dose-rate effect favoring lower flux densities. Heat simulations predict that sample heating will only become an issue for very large dose rates (50?e?Å?2?s?1 or higher) combined with poor thermal contact between the grid and cryo-holder. Secondary radiolytic effects are likely to play a role in dose-rate effects. Stroboscopic data collection combined with an improved understanding of the effects of dose and dose rate will aid single-particle cryo-electron microscopists to have better control of the outcome of their experiments. PMID:21525648

Karuppasamy, Manikandan; Karimi Nejadasl, Fatemeh; Vulovic, Milos; Koster, Abraham J.; Ravelli, Raimond B. G.

2011-01-01

395

First Cryo-Vacuum Test of the JWST Integrated Science Instrument Module  

NASA Astrophysics Data System (ADS)

The integration and test program for the Integrated Science Instrument Module (ISIM) of the James Webb Space Telescope (JWST) calls for three cryo-vacuum tests of the ISIM hardware. The first is a risk-reduction test aimed at checking out the test hardware and procedures; this will be followed by two formal verification tests that will bracket other key aspects of the environmental test program (e.g. vibration and acoustics, EMI/EMC). The first of these cryo-vacuum tests, the risk-reduction test, was executed at NASA’s Goddard Space Flight Center starting in late August, 2013. Flight hardware under test included two (of the eventual four) flight instruments, the Mid-Infrared Instrument (MIRI) and the Fine Guidance Sensor/Near-Infrared Imager and Slitless Spectrograph (FGS/NIRISS), mounted to the ISIM structure, as well as the ISIM Electronics Compartment (IEC). The instruments were cooled to their flight operating temperatures 40K for FGS/NIRISS, ~6K for MIRI) and optically tested against a cryo-certified telescope simulator. Key goals for the risk reduction test included: 1) demonstration of controlled cooldown and warmup, stable control at operating temperature, and measurement of heat loads, 2) operation of the science instruments with ISIM electronics systems at temperature, 3) health trending of the science instruments against instrument-level test results, 4) measurement of the pupil positions and six degree of freedom alignment of the science instruments against the simulated telescope focal surface, 5) detailed optical characterization of the NIRISS instrument, 6) verification of the signal-to-noise performance of the MIRI, and 7) exercise of the Onboard Script System that will be used to operate the instruments in flight. In addition, the execution of the test is expected to yield invaluable logistical experience - development and execution of procedures, communications, analysis of results - that will greatly benefit the subsequent verification tests. At the time of this submission, the hardware had reached operating temperature and was partway through the cryo test program. We report here on the test configuration, the overall process, and the results that were ultimately obtained.

Kimble, Randy A.; Antonille, S. R.; Balzano, V.; Comber, B. J.; Davila, P. S.; Drury, M. D.; Glasse, A.; Glazer, S. D.; Lundquist, R.; Mann, S. D.; McGuffey, D. B.; Novo-Gradac, K. J.; Penanen, K.; Ramey, D. D.; Sullivan, J.; Van Campen, J.; Vila, M. B.

2014-01-01

396

Water activity and mobility in solutions of glycerol and small molecular weight sugars: Implication for cryo- and lyopreservation  

NASA Astrophysics Data System (ADS)

In this study, the free volume models, originally developed for large molecular weight polymer-solvent systems, were used to study the water activity and mobility in solutions of four small molecular weight cryo-/lyoprotectants, viz., glycerol, a monosaccharide (fructose), and two disaccharides (sucrose and trehalose). The free volume model parameters were determined by fitting the models to available experimental data using a nonlinear optimization procedure. It was found that free volume models could accurately predict the available experimental data, which suggests that the free volume models might be generally applicable to aqueous solutions of small molecular weight cryo-/lyoprotectants. Furthermore, several models for estimating the mutual diffusion coefficient were tested using available experimental data for aqueous solutions of glycerol and a better method to estimate the mutual diffusion coefficient was proposed. Free volume models were used to predict and analyze the water activity and mobility in solutions of four cryo-/lyoprotectants under conditions frequently encountered in cryo-/lyopreservation applications. It was found that the water mobility in the glassy state of the above four solutions is essentially negligible in the case of cryopreservation with storage temperature lower than -110°C. However, the water mobility in a glass at higher temperature (>-80°C) may be significant. As a result, a subcooling of up to 50°C may be necessary for the long-term cryo-/lyopreservation of biomaterials depending on the water content and the type of cryo-/lyoprotectants. It was further shown that trehalose might be the best of the four protectants studied for lyopreservation (water mass fraction ?0.1) when the storage temperature is above the room temperature. The results from this study might be useful for the development of more effective protocols for both cryopreservation and lyopreservation of living cells and other biomaterials.

He, Xiaoming; Fowler, Alex; Toner, Mehmet

2006-10-01

397

Tools for macromolecular model building and refinement into electron cryo-microscopy reconstructions  

PubMed Central

The recent rapid development of single-particle electron cryo-microscopy (cryo-EM) now allows structures to be solved by this method at resolutions close to 3?Å. Here, a number of tools to facilitate the interpretation of EM reconstructions with stereochemically reasonable all-atom models are described. The BALBES database has been repurposed as a tool for identifying protein folds from density maps. Modifications to Coot, including new Jiggle Fit and morphing tools and improved handling of nucleic acids, enhance its functionality for interpreting EM maps. REFMAC has been modified for optimal fitting of atomic models into EM maps. As external structural information can enhance the reliability of the derived atomic models, stabilize refinement and reduce overfitting, ProSMART has been extended to generate interatomic distance restraints from nucleic acid reference structures, and a new tool, LIBG, has been developed to generate nucleic acid base-pair and parallel-plane restraints. Furthermore, restraint generation has been integrated with visualization and editing in Coot, and these restraints have been applied to both real-space refinement in Coot and reciprocal-space refinement in REFMAC. PMID:25615868

Brown, Alan; Long, Fei; Nicholls, Robert A.; Toots, Jaan; Emsley, Paul; Murshudov, Garib

2015-01-01

398

Ice sheet elevation change in West Antarctica from CryoSat interferometric altimetry  

NASA Astrophysics Data System (ADS)

Two decades of radar altimetry have shown accelerating mass losses from the Amundsen Sea Sector of West Antarctica. The mass imbalance of this region, which dominates that of all Antarctica, manifests as sustained ice thinning focussed upon fast-flowing ice streams and their tributaries. Ongoing observations are required to determine whether rates of mass loss continue to increase and, more widely, to monitor the stability of this sector of the ice sheet. With the retirement of the ERS-2 satellite in 2011 and the loss of Envisat in 2012, CryoSat-2 offers the unique potential to extend the current altimetry record. In coastal regions of Antarctica the satellite operates in a novel Synthetic Aperture Radar interferometric (SARin) mode, which enables improved resolution and echo location. Here, we apply a repeat track algorithm to SARin mode data to derive ice sheet elevation, volume and mass changes during the period 2010-2013, focussing upon the Amundsen Sea Sector of West Antarctica. Binning elevation change measurements at 5 km resolution gives on average 40 observations per grid cell, illustrating the high sampling density offered by CryoSat-2. We find that, since the cessation of ERS and Envisat measurements, thinning continues to be most pronounced along the fast-flowing ice streams and tributaries, with rates of 4-8 m/yr near the grounding lines of the Pine Island, Thwaites and Smith Glaciers. We compare these new observations to previous measurements made by the ERS and Envisat satellites.

McMillan, M.; Shepherd, A.; Ridout, A.; Sundal, A.

2013-12-01

399

Metallothionein as a clonable high-density marker for cryo-electron microscopy  

PubMed Central

Cryo-electron microscopy is expanding its scope from macromolecules towards much larger and more complex cellular specimens such as organelles, cells and entire tissues. While isolated macromolecular specimens are typically composed of only very few different components that may be recognized by their shape, size or state of polymerization, cellular specimens combine large numbers of proteinaceous structures as well as nucleic acids and lipid arrays. Consequently, an unambiguous identification of these structures within the context of a whole cell may create a very difficult challenge. On plastic-embedded specimens, or Tokuyasu sections, epitopes that are exposed at the surface can be tagged by antibodies. However, vitrified sections have to be kept at strict cryo-conditions (below ?140° C) and therefore do not allow any post-sectioning treatment of the specimens other than data acquisition in the microscope. Hence, the labels have to be placed into the specimen before freezing. Here we report on the application of a small metal-clustering protein, metallothionein (MTH), as a clonable label capable of clustering metal atoms into a high-density particle with high spatial resolution. We tested MTH as a label for kinesin-decorated microtubules (MTs) as well as the building blocks of desmin intermediate filaments (IFs). PMID:22068155

Bouchet-Marquis, Cédric; Pagratis, Maria; Kirmse, Robert; Hoenger, Andreas

2011-01-01

400

Cryo X-ray nano-tomography of vaccinia virus infected cells.  

PubMed

We have performed full-field cryo X-ray microscopy in the water window photon energy range on vaccinia virus (VACV) infected cells to produce tomographic reconstructions. PtK2 cells were infected with a GFP-expressing VACV strain and frozen by plunge fast freezing. The infected cells were selected by light fluorescence microscopy of the GFP marker and subsequently imaged in the X-ray microscope under cryogenic conditions. Tomographic tilt series of X-ray images were used to yield three-dimensional reconstructions showing different cell organelles (nuclei, mitochondria, filaments), together with other structures derived from the virus infection. Among them, it was possible to detect viral factories and two types of viral particles related to different maturation steps of VACV (immature and mature particles), which were compared to images obtained by standard electron microscopy of the same type of cells. In addition, the effect of radiation damage during X-ray tomographic acquisition was analyzed. Thin sections studied by electron microscopy revealed that the morphological features of the cells do not present noticeable changes after irradiation. Our findings show that cryo X-ray nano-tomography is a powerful tool for collecting three-dimensional structural information from frozen, unfixed, unstained whole cells with sufficient resolution to detect different virus particles exhibiting distinct maturation levels. PMID:22178221

Chichón, Francisco Javier; Rodríguez, Maria Josefa; Pereiro, Eva; Chiappi, Michele; Perdiguero, Beatriz; Guttmann, Peter; Werner, Stephan; Rehbein, Stefan; Schneider, Gerd; Esteban, Mariano; Carrascosa, José L

2012-02-01

401

Technical assessment of cryo-compressed hydrogen storage tank systems for automotive applications.  

SciTech Connect

On-board and off-board performance and cost of cryo-compressed hydrogen storage are assessed and compared to the targets for automotive applications. The on-board performance of the system and high-volume manufacturing cost were determined for liquid hydrogen refueling with a single-flow nozzle and a pump that delivers liquid H{sub 2} to the insulated cryogenic tank capable of being pressurized to 272 atm. The off-board performance and cost of delivering liquid hydrogen were determined for two scenarios in which hydrogen is produced by central steam methane reforming (SMR) or by central electrolysis. The main conclusions are that the cryo-compressed storage system has the potential of meeting the ultimate target for system gravimetric capacity, mid-term target for system volumetric capacity, and the target for hydrogen loss during dormancy under certain conditions of minimum daily driving. However, the high-volume manufacturing cost and the fuel cost for the SMR hydrogen production scenario are, respectively, 2-4 and 1.6-2.4 times the current targets, and the well-to-tank efficiency is well short of the 60% target specified for off-board regenerable materials.

Ahluwalia, R.; Hua, T.; Peng, J.-K.; Lasher, S.; McKenney, K.; Sinha, J.; Gardiner, M.; Nuclear Engineering Division; TIAX LLC; U.S. DOE

2010-05-01

402

Morphology of Influenza B/Lee/40 Determined by Cryo-Electron Microscopy  

PubMed Central

Cryo-electron microscopy projection image analysis and tomography is used to describe the overall architecture of influenza B/Lee/40. Algebraic reconstruction techniques with utilization of volume elements (blobs) are employed to reconstruct tomograms of this pleomorphic virus and distinguish viral surface spikes. The purpose of this research is to examine the architecture of influenza type B virions by cryo-electron tomography and projection image analysis. The aims are to explore the degree of ribonucleoprotein disorder in irregular shaped virions; and to quantify the number and distribution of glycoprotein surface spikes (hemagglutinin and neuraminidase) on influenza B. Projection image analysis of virion morphology shows that the majority (?83%) of virions are spherical with an average diameter of 134±19 nm. The aspherical virions are larger (average diameter?=?155±47 nm), exhibit disruption of the ribonucleoproteins, and show a partial loss of surface protein spikes. A count of glycoprotein spikes indicates that a typical 130 nm diameter type B virion contains ?460 surface spikes. Configuration of the ribonucleoproteins and surface glycoprotein spikes are visualized in tomogram reconstructions and EM densities visualize extensions of the spikes into the matrix. The importance of the viral matrix in organization of virus structure through interaction with the ribonucleoproteins and the anchoring of the glycoprotein spikes to the matrix is demonstrated. PMID:24516628

Katz, Garrett; Benkarroum, Younes; Wei, Hui; Rice, William J.; Bucher, Doris; Alimova, Alexandra; Katz, Al; Klukowska, Joanna; Herman, Gabor T.; Gottlieb, Paul

2014-01-01

403

Water discharge during an Antarctic subglacial flood from CryoSat interferometric altimetry. (Invited)  

NASA Astrophysics Data System (ADS)

Beneath the Antarctic Ice Sheet lies a network of subglacial lakes which can store, and periodically release, some of the estimated 65 Gt of water generated annually by subglacial melting. These lakes produce a system of episodic mass transfer at the ice sheet base, with the capacity to alter the subglacial environment, the flow of overlying ice and the delivery of freshwater to the ocean. In this study, we use data acquired by the CryoSat-2 interferometric radar altimeter to map the perimeter and depth of a 260 km2 surface depression above an Antarctic subglacial lake (SGL). In combination with ICESat laser altimetry, we chart decadal changes in SGL volume. During 2007-2008, between 4.9 and 6.4 km3 of water drained from the SGL, and peak discharge exceeded 160 m3s-1. The flood was twice as large as any previously recorded, and equivalent to ~ 10 % of the meltwater generated annually beneath the ice sheet. The ice surface has since uplifted at a rate of 5.6 × 2.8 m yr-1. Our study demonstrates the ability of CryoSat-2 to provide detailed maps of ice sheet topography, its potential to accurately measure SGL drainage events, and the contribution it can make to understanding mass transport beneath the Antarctic Ice Sheet.

McMillan, M.; Corr, H.; Shepherd, A.; Ridout, A.; Laxon, S.; Cullen, R.

2013-12-01

404

Cryo-EM Structure of Isomeric Molluscan Hemocyanin Triggered by Viral Infection  

PubMed Central

Hemocyanins (Hcs) of arthropods and mollusks function not only as oxygen transporters, but also as phenoloxidases (POs). In invertebrates, PO is an important component in the innate immune cascade, where it functions as the initiator of melanin synthesis, a pigment involved in encapsulating and killing of pathogenic microbes. Although structures of Hc from several species of invertebrates have been reported, the structural basis for how PO activity is triggered by structural changes of Hc in vivo remains poorly understood. Here, we report a 6.8 Å cryo-electron microscopy (cryo