Sample records for cryo magnetic separation

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

    PubMed Central

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

    2011-01-01

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

  2. A Method to Estimate the Optimum Temperature for the Cryo-Shattering Separation Using a Charpy Impact Tester

    NASA Astrophysics Data System (ADS)

    Hagura, Yoshio; Watanabe, Hisahiko

    A cryo-shattering separation is a recently developed separation method which is applied to collect low-fat meat from fatty fish. This separation method needs to be operated at the optimum temperature for the cryo-shattering. Determining on optimum temperature needs much works and costs. In this study,an easy method to estimate the optimum temperature for cryo-shattering was proposed using a Charpy impact tester. Four kinds of characteristic temperatures observed through impact tests were used to construct a fracture-temperature-map. By use of the map,the optimum temperature for cryo-shattering was obtained without shattering/sieving experiments.

  3. Microfluidically Cryo-Cooled Planar Coils for Magnetic Resonance Imaging 

    E-print Network

    Koo, Chiwan

    2013-08-09

    is approximately the same as the diameters of the microcoils. Here microfluidic technology is utilized to locally cryo-cool the microcoils and minimize the thermal isolation gap so that the imaging surface is within the imaging depth of the microcoils. The first...

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

    NASA Astrophysics Data System (ADS)

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

    2014-01-01

    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.

  5. Microfluidically Cryo-Cooled Planar Coils for Magnetic Resonance Imaging

    E-print Network

    Koo, Chiwan

    2013-08-09

    High signal-to-noise ratio (SNR) is typically required for higher resolution and faster speed in magnetic resonance imaging (MRI). Planar microcoils as receiver probes in MRI systems offer the potential to be configured into array elements for fast...

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

    NASA Astrophysics Data System (ADS)

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

    2013-03-01

    Recently, rare-earth-free permanent magnets (REFPMs) have attracted much attention globally owing to rare-earth metal crisis and high cost. Among the REFPMs, MnBi is a potential candidate due to its unusual large magnetocrystalline anisotropy (K ~ 107 erg/cc) and positive temperature of coefficient of coercivity. In this work, we report for the first time a novel processing method that combines the cryo-milling with hot compaction to produce fully dense bulk nanostructured MnBi magnet. The effect of cryo-milling on particle size, phase formation, and magnetic properties of MnBi has been studied in detail. Also, the microstructural and magnetic properties of bulk nanostructured MnBi magnet were investigated. Adoption of cryo-milling results in nanocrystalline powders with particle size of 400-500 nm. Large coercivity (Hc) values of 18.5 kOe, and 12.9 kOe were obtained in cryo-milled powders and hot compacted magnet respectively. The MnBi magnet shows a large positive temperature coefficient of Hc and the Hc reaches a value of more than 30 kOe above 450 K. Recently, rare-earth-free permanent magnets (REFPMs) have attracted much attention globally owing to rare-earth metal crisis and high cost. Among the REFPMs, MnBi is a potential candidate due to its unusual large magnetocrystalline anisotropy (K ~ 107 erg/cc) and positive temperature of coefficient of coercivity. In this work, we report for the first time a novel processing method that combines the cryo-milling with hot compaction to produce fully dense bulk nanostructured MnBi magnet. The effect of cryo-milling on particle size, phase formation, and magnetic properties of MnBi has been studied in detail. Also, the microstructural and magnetic properties of bulk nanostructured MnBi magnet were investigated. Adoption of cryo-milling results in nanocrystalline powders with particle size of 400-500 nm. Large coercivity (Hc) values of 18.5 kOe, and 12.9 kOe were obtained in cryo-milled powders and hot compacted magnet respectively. The MnBi magnet shows a large positive temperature coefficient of Hc and the Hc reaches a value of more than 30 kOe above 450 K. The work was supported by Siemens.

  7. Magnetic separation for soil decontamination

    SciTech Connect

    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

    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.

  8. Magnetic separation for soil decontamination

    SciTech Connect

    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

    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.

  9. Continuous magnetic separator and process

    DOEpatents

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

    2008-04-22

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

  10. Development of magnetic device for cell separation

    NASA Astrophysics Data System (ADS)

    Haik, Yousef; Pai, Vinay; Chen, Ching-Jen

    1999-04-01

    A magnetic device that separates red blood cells from the whole blood on a continuous basis is presented. The device utilizes permanent magnets in alternating spatial arrangements. Red blood cells are coupled with magnetic microspheres to facilitate the magnetic separation. Effectiveness of red blood cells separation and purity of plasma solution was improved using the device over conventional centrifugal methods.

  11. Method of magnetic separation and apparatus therefore

    NASA Technical Reports Server (NTRS)

    Oder, Robin R. (Inventor)

    1991-01-01

    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.

  12. Separation of magnetic field lines

    SciTech Connect

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

    2012-11-15

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

  13. Magnetic Separator Enhances Treatment Possibilities

    NASA Technical Reports Server (NTRS)

    2008-01-01

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

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

    SciTech Connect

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

    1994-05-01

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

  15. HTS High Gradient Magnetic Separation system

    Microsoft Academic Search

    M. A. Daugherty; J. Y. Coulter; W. L. Hults

    1996-01-01

    We report on the assembly, characterization and operation of a high temperature superconducting (HTS) magnetic separator. The magnet is made of 624 m of Silver\\/BSCCO superconducting wire and has overall dimensions of 18 cm OD, 15.5 cm height and 5 cm ID. The HTS current leads are designed to operate with the warm end at 75 K and the cold

  16. HTS high gradient magnetic separation system

    Microsoft Academic Search

    M. A. Daugherty; J. Y. Coulter; W. L. Hults; D. E. Daney; D. D. Hill; D. E. McMurry; M. C. Martinez; L. G. Phillips; J. O. Willis; H. J. Boenig; F. C. Prenger; A. J. Rodenbush; S. Young

    1997-01-01

    We report on the assembly, characterization and operation of a high temperature superconducting (HTS) magnetic separator. The magnet is made of 624 m of Silver\\/BSCCO superconducting wire and has overall dimensions of 18 cm OD, 15.5 cm height and 5 cm ID. The HTS current leads are designed to operate with the warm end at 75 K and the cold

  17. A PURPOSE ORIENTED MAGNETIC SEPARATOR: SKIMMER

    SciTech Connect

    Salih Ersayin

    2005-08-09

    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.

  18. Coal preparation using magnetic separation. Volume 1. Magnetic separation study of Magnex processed coal

    SciTech Connect

    Porter, C.R.; Goens, D.N.

    1980-07-01

    The EPRI funded program was instituted to assess the capability of commercially available magnetic separators to process carbonyl treated coals from the Magnex Process. The Magnex Process is a dry beneficiation process which involves: (1) crushing, (2) heating, (3) carbonyl treatment, and (4) magnetic separation. The coal is crushed to nominally minus 4-mesh prior to treatment. The crushed coal is heated to approximately 170/sup 0/C (338/sup 0/F) then subjected to iron carbonyl vapors. Pyrite and ash are removed from the coal with low to medium intensity magnetic separators. Four kilogram samples of Magnex Processed coal were sent to each of five vendors who were interested in the applicability of their equipment for use in the Magnex Process. Three vendors, Eriez, Reading US, and Carpco demonstrated the capability to separate the magnetic material from the carbonyl treated coal using induced-magnetic-roll (IMR) separators. Each vendor evaluated and recommended the magnetic separator they considered most capable of handling the carbonyl treated coal. The IMR Separator was most often recommended and produced the best results by the vendors. A test program was initiated using the Eriez IMR Separator in conjunction with the Magnex Pilot Plant to optimize the IMR parameters of feed rate, current, roll speed, magnetic gap, size magnetic coil current, magnetic coil resistance, divider settings, and size fraction. The resulting preferred values for the parameters are attached on Table 1-1.

  19. HTS High Gradient Magnetic Separation system

    SciTech Connect

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

    1996-09-01

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

  20. A Continuous Throughput Micro Magnetic Cell Separator

    NASA Astrophysics Data System (ADS)

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

    2004-03-01

    Micro-fluidic total analysis systems for diagnosis, research and treatment require foolproof sorting and separation techniques. A bulk fluid sample invariably contains unwanted and useless matter that must be disposed of. The chip must first be able to separate the wheat from the chaff before doing any analysis. A micro-fluidic device that continuously separates blood cells from a whole blood sample via immunomagnetic labeling has been built. The device differentiates the flow of labeled cells from all other blood components such as RBC's, plasma, viruses, proteins and other unwanted blood components. A fluid sample passes over an array of micro-fabricated permanent magnets which alter the flow of cells tagged with magnetic beads. Separated target cells, for example CD4 positive WBCs, can then be passed on to subsequent phases on the TAS chip, ultimately allowing fast pheno and geno typing of cells from bulk fluid samples.

  1. Dual Magnetic Separator for TRI$?$P

    E-print Network

    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

    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.

  2. Prediction of Separation Performance of Dry High Intensity Magnetic Separator for Processing of Para-Magnetic Minerals

    NASA Astrophysics Data System (ADS)

    Tripathy, Sunil Kumar; Singh, Veerendra; Suresh, Nikkam

    2015-03-01

    High intensity dry magnetic separators are gaining popularity for the separation of para-magnetic minerals due to the cost economic factor. Induced roll magnetic separator is found to be an effective dry separator for the separation of fine particles. Separation efficiency of this separator depends on mineral characteristics and the design features of equipment along with the optimization of process variables. Present investigation focuses on the prediction and validation of separation performance of minerals while treating in induced roll magnetic separator. Prediction of the separation is expressed in terms of separation angle at which a particle leaves the rotor surface by using a modified particle flow model derived by Cakir. The validation of the model is carried by capturing the particle trajectory using an image analyzer. It is found that Cakir's mathematical model produces reliable results and a new model is proposed to increase the reliability of separation angle prediction by including the particle shape factor.

  3. MSWI boiler fly ashes: magnetic separation for material recovery.

    PubMed

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

    2011-07-01

    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

  4. Temperature and magnetic dual responsive microparticles for DNA separation

    Microsoft Academic Search

    Abdelhamid Elaissari

    2011-01-01

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

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

    PubMed

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

    2011-01-01

    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

  6. Development of high gradient magnetic separation system under dry condition

    NASA Astrophysics Data System (ADS)

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

    2010-11-01

    The interfusion of impurities such as metallic wear debris has been a problem in the manufacturing process of foods, medicines, and industrial products. Gravity separation system and membrane separation system has been used widely for powder separation, however magnetic separation system is much efficient to separate magnetic particles. Magnetic separation system under wet process is used conventionally, however, it has some demerit such as necessity of drying treatment after separation and difficulty of running the system in the cold region and so on. Thus, magnetic separation under dry process is prospective as alternative method. In this paper, we developed high gradient magnetic separation system (HGMS) under dry process. In dry HGMS system, powder coagulation caused by particle interaction is considerable. Powder coagulation causes a blockage of magnetic filters and results in decrease of separation performance of dry HGMS system. In order to investigate the effect of powder coagulation on separation performance, we conducted experiments with two kinds of powdered materials whose cohesive properties are different.

  7. Magnetically Stabilized Fluidized Beds for Solids Separation by Density

    Microsoft Academic Search

    R. E. Rosensweig; W. K. Lee; J. H. Siegell

    1987-01-01

    Systems for the dry separation of solids by density difference are described. They consist of a magnetically stabilized fluidized bed (MSB) as a host medium in which heavy solids sink and light solids float. The magnetic stabilization produces a fluidized medium with the absence of gas bubbling and thus enhances the separations efficiency by preventing remixing of the feed solids

  8. High gradient magnetic separation applied to environmental remediation

    SciTech Connect

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

    1993-08-01

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

  9. Magnetic separation of micro-spheres from viscous biological fluids.

    SciTech Connect

    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

    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.

  10. Magnetic separator having a multilayer matrix, method and apparatus

    DOEpatents

    Kelland, David R. (Lexington, MA)

    1980-01-01

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

  11. Microstripes for transport and separation of magnetic particles

    PubMed Central

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

    2012-01-01

    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

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

    E-print Network

    Kasagi, Nobuhide

    experiments using plastic particles as model cells, and demonstrated that the number of separated particles separator Hiromichi Inokuchi, Yuji Suzuki and Nobuhide Kasagi A novel micro immuno-magnetic cell sorting for labeling target cells with magnetic beads, and a separator with an embedded coil, where continuous cell

  13. Separation of Magnetic Field Lines in Two-Component Turbulence

    NASA Astrophysics Data System (ADS)

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

    2004-10-01

    The problem of the separation of random magnetic field lines in collisionless astrophysical plasmas is closely related to the problem of the magnetic field line random walk and is highly relevant to the transport of charged particles in turbulent plasmas. In order to generalize treatments based on quasi-linear theory, here we examine the separation of nearby magnetic field lines by employing a nonperturbative technique based on the Corrsin independence hypothesis. Specifically, we consider the case of two-component turbulence in which the magnetic field fluctuations are a mixture of one-dimensional (slab) and two-dimensional ingredients, as a concrete example of anisotropic turbulence that provides a useful description of turbulence in the solar wind. We find that random field trajectories can separate in general through three regimes of the behavior of the running diffusion coefficient: slow diffusive separation, an intermediate regime of superdiffusion, and fast diffusive separation at large distances. These features are associated with the gradual, exponential divergence of field lines within islands of two-dimensional turbulence, followed by diffusive separation at long distances. The types of behavior are determined not by the Kubo number but rather a related ratio that takes the turbulence anisotropy into account. These results are confirmed by computer simulations. We discuss implications for space observations of energetic charged particles, including ``dropouts'' of solar energetic particles.

  14. Inverted Linear Halbach Array for Separation of Magnetic Nanoparticles

    PubMed Central

    Ijiri, Y.; Poudel, C.; Williams, P.S.; Moore, L.R.; Orita, T.; Zborowski, M.

    2014-01-01

    A linear array of Nd-Fe-B magnets has been designed and constructed in an inverted Halbach configuration for use in separating magnetic nanoparticles. The array provides a large region of relatively low magnetic field, yet high magnetic field gradient in agreement with finite element modeling calculations. The magnet assembly has been combined with a flow channel for magnetic nanoparticle suspensions, such that for an appropriate distance away from the assembly, nanoparticles of higher moment aggregate and accumulate against the channel wall, with lower moment nanoparticles flowing unaffected. The device is demonstrated for iron oxide nanoparticles with diameters of ~ 5 and 20 nm. In comparison to other approaches, the inverted Halbach array is more amenable to modeling and to scaling up to preparative quantities of particles. PMID:25382864

  15. Modeling high gradient magnetic separation from biological fluids.

    SciTech Connect

    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

    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.

  16. Process to remove actinides from soil using magnetic separation

    DOEpatents

    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

    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.

  17. Magnetic particle separation process for hazardous and radionuclide elements

    SciTech Connect

    Nunez, L. [Argonne National Lab., IL (United States); Pourfarzaneh, M. [Cortex-Biochem, Inc., San Leandro, CA (United States)

    1997-12-31

    The magnetically assisted chemical separation program was initially funded by DOE EM-50 to develop processes for the efficient separation of radionuclides and other hazardous metals. This process has stimulated the partnership between industry and ANL for many applications related to hazardous metal problems in industry. In-tank or near-tank hazardous metals separation using magnetic particles that have selective coating is a new approach to the problems of metal removal and recycling [of industrial (e.g., mining, printing circuit board, plating)] corrosive waste streams. This concept of coated magnetic particles promises simple, compact processing at very low costs and employs mature chemical separations technologies to remove and recover hazardous metals from aqueous solutions. The selective chemical extractants are attached to inexpensive magnetic carrier particles. Surfaces of small particles composed of rare earths or ferromagnetic materials are treated to retain chemical extractants (e.g., TBP, CMPO, quaternary amines, carboxylic acid). After selective partitioning of contaminants to the surface layer, magnets are used to collect the loaded particles from the tank. The particles can be regenerated by stripping the contaminants and the selective metals can be recovered and recycled from the strip solution. This process and its related equipment are simple enough to be used for recovery/recycling and waste minimization activities at many industrial sites. Both the development of the process for hazardous and radioactive waste and the transfer of the technology will be discussed.

  18. Metals separation using solvent extractants on magnetic microparticles

    SciTech Connect

    Nunez, L. [Argonne National Lab., IL (United States); Pourfarzaneh, M. [CORTEX-BIOCHEM, Inc., San Leandro, CA (United States)

    1997-12-31

    The magnetically assisted chemical separation program was initially funded by DOE EM-50 to develop processes for the efficient separation of radionuclides and other hazardous metals. This process has simulated the partnership between industry and ANL for many applications related to hazardous metal problems in industry. In-tank or near-tank hazardous metals separation using magnetic particles promises simple, compact processing at very low costs and employs mature chemical separations technologies to remove and recover hazardous metals from aqueous solutions. The selective chemical extractants are attached to inexpensive magnetic carrier particles. Surfaces of small particles composed of rare earths or ferromagnetic materials are treated to retain chemical extractants (e.g., TBP, CMPO, quaternary amines, carboxylic acid). After selective partitioning of contaminants to the surface layer, magnets are used to collect the loaded particles from the tank. The particles can be regenerated by stripping the contaminants and the selective metals can be recovered and recycled from the strip solution. This process and its related equipment are simple enough to be used for recovery/recycling and waste minimization activities at many industrial sites. Both the development of the process for hazardous and radioactive waste and the transfer of the technology will be discussed.

  19. Magnetic Separations with Magnetite: Theory, Operation, and Limitations

    SciTech Connect

    G. B. Cotten

    2000-08-01

    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.

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

    NASA Astrophysics Data System (ADS)

    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

    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.

  1. Particle acceleration at 3D reconnecting magnetic separators

    NASA Astrophysics Data System (ADS)

    Threlfall, James; Neukirch, Thomas; Parnell, Clare; Stevenson, Julie

    2015-04-01

    We present results of test particle orbit calculations in three different environments which model separator reconnection in three dimensions. The test particle (electron and proton) orbits are calculated using the relativistic guiding centre approximation. We investigate test particle orbits in a time-dependent (analytical) electro-magnetic field configuration [detailed in Threlfall et al. (A&A, in press); arXiv:1410.6465]. These results are also compared with orbits based upon large-scale 3D MHD simulations of both a single reconnecting magnetic separator and an observationally driven 3D model of a solar active region which contains several topological features of interest, including separators. We discuss how the test-particle orbits and the energy gain depend on the initial conditions, and how observations (for example, of solar flares) may be used to constrain model parameters.

  2. Compositional separation in Co-Mn magnetic thin films

    NASA Astrophysics Data System (ADS)

    Rogers, David J.; Maeda, Yasushi; Takei, Koji

    1995-11-01

    The compositional distribution in fcc Co-Mn magnetic thin films was studied in order to examine the possibility of a compositional separation, similar to that observed previously in hcp Co-Cr thin film magnetic recording media, occurring in an fcc alloy system. Spin-echo 59Co NMR study of Co75Mn25 films revealed a change from a homogeneous compositional distribution in a film deposited at a substrate temperature (Ts) of RT to a compositionally separated state in a film deposited at a Ts of 300 °C. Vibrating sample magnetometry revealed an associated three-fold enhancement in saturation magnetization in the films deposited at a Ts of 300 °C.

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

    PubMed

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

    2014-06-01

    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

  4. Magnetic nano-sorbents for fast separation of radioactive waste

    SciTech Connect

    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

    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)

  5. The rate of separation of magnetic lines of force in a random magnetic field.

    NASA Technical Reports Server (NTRS)

    Jokipii, J. R.

    1973-01-01

    The mixing of magnetic lines of force, as represented by their rate of separation, as a function of distance along the magnetic field, is considered with emphasis on neighboring lines of force. This effect is particularly important in understanding the transport of charged particles perpendicular to the average magnetic field. The calculation is carried out in the approximation that the separation changes by an amount small compared with the correlation scale normal to the field, in a distance along the field of a few correlation scales. It is found that the rate of separation is very sensitive to the precise form of the power spectrum. Application to the interplanetary and interstellar magnetic fields is discussed, and it is shown that in some cases field lines, much closer together than the correlation scale, separate at a rate which is effectively as rapid as if they were many correlation lengths apart.

  6. Magnetic reconnection in 3D magnetosphere models: magnetic separators and open flux production

    NASA Astrophysics Data System (ADS)

    Glocer, A.; Dorelli, J.; Toth, G.; Komar, C. M.; Cassak, P.

    2014-12-01

    There are multiple competing definitions of magnetic reconnection in 3D (e.g., Hesse and Schindler [1988], Lau and Finn [1990], and Boozer [2002]). In this work we focus on separator reconnection. A magnetic separator can be understood as the 3D analogue of a 2D x line with a guide field, and is defined by the line corresponding to the intersection of the separatrix surfaces associated with the magnetic nulls. A separator in the magnetosphere represents the intersection of four distinct magnetic topologies: solar wind, closed, open connected to the northern hemisphere, and open connected to the southern hemisphere. The integral of the parallel electric field along the separator defines the rate of open flux production, and is one measure of the reconnection rate. We present three methods for locating magnetic separators and apply them to 3D resistive MHD simulations of the Earth's magnetosphere using the BATS-R-US code. The techniques for finding separators and determining the reconnection rate are insensitive to IMF clock angle and can in principle be applied to any magnetospheric model. The present work examines cases of high and low resistivity, for two clock angles. We also examine the separator during Flux Transfer Events (FTEs) and Kelvin-Helmholtz instability.

  7. Beneficiation of Turkish lignites by thermal treatment and magnetic separation

    SciTech Connect

    Onal, G.; Renda, D.; Mustafaev, I.; Dogan, Z.

    1999-07-01

    In this paper, the improvement of Turkish lignites by semi-coking and REMS magnetic separation, in two stages, is discussed. The oxidation and decomposition of pyrite through the thermal treatment result in the formation of iron oxide and pyrrhotite on the surface. In addition to pyrite, part of the organic sulfur is also removed. After thermal treatment of lignites at temperatures ranging from 370 to 650 C, the application of REMS magnetic separator produces a product higher in calorific value and lower in sulfur content. The product can be utilized after briquetting. The volatile gases can also be used after sulfur removal. This process appears to be feasible as a clean coal manufacture from the point of energy efficiency. A short economic analysis is also presented.

  8. D0 Cryo System ODH and Cryo Alarm System Response

    SciTech Connect

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

    1990-04-05

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

  9. Radiolysis and hydrolysis of magnetically assisted chemical separation particles

    SciTech Connect

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

    1995-05-01

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

  10. Conduction-cooled Bi 2Sr 2Ca 2Cu 3O x (Bi2223) magnet for magnetic separation

    Microsoft Academic Search

    H. Kumakura; T. Ohara; H. Kitaguchi; K. Togano; H. Wada; H. Mukai; K. Ohmatsu; H. Takei

    2001-01-01

    A prototype of a conduction-cooled Bi2Sr2Ca2Cu3Ox (Bi-2223) magnet system for magnetic separation was constructed. The magnet system has a 200 mm room temperature bore and generates fields higher than 1 T in an 11-liter room temperature space. The magnet axis of the system was designed to be horizontal in order to attain effective magnetic separation. The magnet consisted of 42

  11. Plasma separation process: Magnet move to Oak Ridge National Laboratory

    SciTech Connect

    Not Available

    1989-07-01

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

  12. Cryo Utilities Room Cooling System

    SciTech Connect

    Ball, G.S.; /Fermilab

    1989-01-26

    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.

  13. Persistent topology for cryo-EM data analysis.

    PubMed

    Xia, Kelin; Wei, Guo-Wei

    2015-08-01

    In this work, we introduce persistent homology for the analysis of cryo-electron microscopy (cryo-EM) density maps. We identify the topological fingerprint or topological signature of noise, which is widespread in cryo-EM data. For low signal-to-noise ratio (SNR) volumetric data, intrinsic topological features of biomolecular structures are indistinguishable from noise. To remove noise, we employ geometric flows that are found to preserve the intrinsic topological fingerprints of cryo-EM structures and diminish the topological signature of noise. In particular, persistent homology enables us to visualize the gradual separation of the topological fingerprints of cryo-EM structures from those of noise during the denoising process, which gives rise to a practical procedure for prescribing a noise threshold to extract cryo-EM structure information from noise contaminated data after certain iterations of the geometric flow equation. To further demonstrate the utility of persistent homology for cryo-EM data analysis, we consider a microtubule intermediate structure Electron Microscopy Data (EMD 1129). Three helix models, an alpha-tubulin monomer model, an alpha-tubulin and beta-tubulin model, and an alpha-tubulin and beta-tubulin dimer model, are constructed to fit the cryo-EM data. The least square fitting leads to similarly high correlation coefficients, which indicates that structure determination via optimization is an ill-posed inverse problem. However, these models have dramatically different topological fingerprints. Especially, linkages or connectivities that discriminate one model from another, play little role in the traditional density fitting or optimization but are very sensitive and crucial to topological fingerprints. The intrinsic topological features of the microtubule data are identified after topological denoising. By a comparison of the topological fingerprints of the original data and those of three models, we found that the third model is topologically favored. The present work offers persistent homology based new strategies for topological denoising and for resolving ill-posed inverse problems. Copyright © 2015?John Wiley & Sons, Ltd. PMID:25851063

  14. On-chip Magnetic Separation and Cell Encapsulation in Droplets†

    PubMed Central

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

    2014-01-01

    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

  15. Cryo Utilities Room Cooling System

    Microsoft Academic Search

    G. S. Ball

    1989-01-01

    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

  16. Monte Carlo study of phase separation in magnetic insulators

    E-print Network

    Murawski, Szymon; Paw?owski, Grzegorz; Robaszkiewicz, Stanis?aw

    2015-01-01

    In this work we focus on the study of phase separation in the zero-bandwidth extended Hubbard with nearest-neighbors intersite Ising-like magnetic interactions $J$ and on-site Coulomb interactions $U$. The system has been analyzed by means of Monte Carlo simulations (in the grand canonical ensemble) on two dimensional square lattice (with $N=L\\times L =400$ sites) and the results for $U/(4J)=2$ as a function of chemical potential and electron concentration have been obtained. Depending on the values of interaction parameters the system exhibits homogeneous (anti-)ferromagnetic (AF) or non-ordered (NO) phase as well as phase separation PS:AF/NO state. Transitions between homogeneous phases (i.e. AF-NO transitions) can be of first or second order and the tricritical point is also present on the phase diagrams. The electron compressibility $K$ is an indicator of the phase separation and that quantity is of particular interest of this paper.

  17. Correlations, spin-charge separation, and magnetic anisotropy

    NASA Astrophysics Data System (ADS)

    Skomski, Ralph; Manchanda, Priyanka

    2015-03-01

    Much of the physics of condensed matter reflects electron-electron correlations. On an independent-electron level, correlations are described by a single Slater determinant with broken spin symmetry. This approach includes Hund's rule correlations as well the LSDA and LSDA+U approximations to density-functional theory (DFT). However, from Kondo and heavy-fermion systems it is known that the independent-electron approach fails to describe spin-charge separation in strongly correlated systems, necessitating the use of two or more Slater determinants. Using first-principle and model calculations, we show that spin-charge separation strongly affects the leading rare-earth anisotropy contribution in top-end permanent magnet materials such as Nd2Fe14B and SmCo5. Explicit correlation results are obtained for two limiting cases. First, we derive the density functional for tripositive rare-earth ions in a Bethe-type crystal field. The potential looks very different from the LSDA(+U) potentials, including gradient corrections. Second, we use a simple model to show that Kondo-type spin-charge separation yield a rare-earth anisotropy contribution absent in the independent-electron approach. This research is supported by DOE (DE-FG02-04ER46152).

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

    NASA Astrophysics Data System (ADS)

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

    2009-10-01

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

  19. Demonstration of magnetically activated and guided isotope separation

    NASA Astrophysics Data System (ADS)

    Mazur, Thomas R.; Klappauf, Bruce; Raizen, Mark G.

    2014-08-01

    Enriched isotopes are widely used in medicine, basic science and energy production, and the need will only grow in the future. The main method for enriching stable isotopes today, the calutron, dates back over eighty years and has an uncertain future, creating an urgent need, especially in nuclear medicine. We report here the experimental realization of a general and efficient method for isotope separation that presents a viable alternative to the calutron. Combining optical pumping and a unique magnet geometry, we observe substantial depletion of Li-6 throughput in a lithium atomic beam produced by an evaporation source over a range of flux. These results demonstrate the viability of our method to yield large degrees of enrichment in a manner that is amenable to industrial scale-up and the production of commercially relevant quantities.

  20. Magnetic separation - Advanced nanotechnology for future nuclear fuel recycle

    SciTech Connect

    Kaur, M.; Zhang, H.; Qiang, Y. [Department of Physics and Environmental Science, University of Idaho, Moscow, ID 83844 (United States); Martin, L.; Todd, T. [Idaho National Laboratory, Idaho Falls, ID 83415 (United States)

    2013-07-01

    The unique properties of magnetic nanoparticles (MNPs), such as their extremely small size and high surface area to volume ratio, provide better kinetics for the adsorption of metal ions from aqueous solutions. In this work, we demonstrated the separation of minor actinides using complex conjugates of MNPs with diethylenetriamine-pentaacetic acid (DTPA) chelator. The sorption results show the strong affinity of DTPA towards Am (III) and Pu (IV) by extracting 97% and 80% of actinides, respectively. It is shown that the extraction process is highly dependent on the pH of the solution. If these long-term heat generating actinides 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. (authors)

  1. 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...

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

    NASA Astrophysics Data System (ADS)

    Wang, Shaohua; Zhou, Shaoqi

    2010-08-01

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

  3. Magnetic separation studies on ferruginous chromite fine to enhance Cr:Fe ratio

    NASA Astrophysics Data System (ADS)

    Tripathy, Sunil Kumar; Banerjee, P. K.; Suresh, Nikkam

    2015-03-01

    The Cr:Fe ratio (chromium-to-iron mass ratio) of chromite affects the production of chrome-based ferroalloys. Although the literature contains numerous reports related to the magnetic separation of different minerals, limited work concerning the application of magnetic separation to fine chromite from the Sukinda region of India to enhance its Cr:Fe ratio has been reported. In the present investigation, magnetic separation and mineralogical characterization studies of chromite fines were conducted to enhance the Cr:Fe ratio. Characterization studies included particle size and chemical analyses, X-ray diffraction analysis, automated mineral analysis, sink-and-float studies, and magnetic susceptibility measurements, whereas magnetic separation was investigated using a rare earth drum magnetic separator, a rare earth roll magnetic separator, an induced roll magnetic separator, and a wet high-intensity magnetic separator. The fine chromite was observed to be upgraded to a Cr:Fe ratio of 2.2 with a yield of 55.7% through the use of an induced roll magnetic separator and a feed material with a Cr:Fe ratio of 1.6.

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

    NASA Astrophysics Data System (ADS)

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

    2011-11-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2011-11-01

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

  6. Selective separation of fluorescent-magnetic nanoparticles with different magnetite-doping levels.

    PubMed

    Park, Sang-Eun; Park, Sang-Joon; Lee, Sang-Wha; Lee, Joong-Kee

    2011-05-01

    Fluorescent-labeled magnetic nanoparticles were explored as a biomedical agent for selective magnetic separation. By adjusting the loading volume of citrate-stabilized magnetites during a sol-gel reaction with silicon alkoxide, magnetites were simultaneously embedded into both the surface and inside the silica matrix, consequently leading to magnetic nanoparticles with different doping levels of magnetites. For endowing them with multifunctional tools in biomedical fields, magnetic nanoparticles were further encapsulated with silica thin layer labeled with fluorescent organic dyes (such as Alexa Fluor 488 and 594). Fluorescent-magnetic nanoparticles with different magnetism successfully displayed the differential separation of fluorescence spectra under an external magnetic field. PMID:21780495

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

    NASA Astrophysics Data System (ADS)

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

    2010-12-01

    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.

  8. 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...

  9. Phosphate removal from solution using steel slag through magnetic separation.

    PubMed

    Xiong, Jibing; He, Zhenli; Mahmood, Qaisar; Liu, Dan; Yang, Xiaoe; Islam, Ejazul

    2008-03-21

    Steel slag with magnetic separation was used to remove phosphate from aqueous solutions. The influence of adsorbent dose, pH, and temperature on phosphate removal was investigated in a series of batch experiments. Phosphate removal increased with the increasing temperature, adsorbent dose and decreased with increasing initial phosphate concentrations, while it was at its peak at pH of 5.5. The phosphate removal predominantly occurred through ion exchange. The specific surface area of the steel slag was 2.09m2/g. The adsorption of phosphate followed both Langmuir and Freundlich isotherms. The maximum adsorption capacity of the steel slag was 5.3mgP/g. The removal rates of total phosphorus (TP) and dissolved phosphorus (DP) from secondary effluents were 62-79% and 71-82%, respectively. Due to their low cost and high capability, it was concluded that the steel slag may be an efficient adsorbent to remove phosphate both from solution and wastewater. PMID:17703877

  10. Integrated acoustic and magnetic separation in microfluidic channels Jonathan D. Adams,1

    E-print Network

    Fygenson, Deborah Kuchnir

    Integrated acoustic and magnetic separation in microfluidic channels Jonathan D. Adams,1 Patrick on the integration of microfluidic acoustic and magnetic separation in a monolithic device for multiparameter-performance, multiparameter cell sorting in dis- posable devices.8­10 We report here on the integration of acoustic

  11. A smart fully integrated micromachined separator with soft magnetic micro-pillar arrays for cell isolation

    NASA Astrophysics Data System (ADS)

    Dong, Tao; Su, Qianhua; Yang, Zhaochu; Zhang, Yulong; Egeland, Eirik B.; Gu, Dan D.; Calabrese, Paolo; Kapiris, Matteo J.; Karlsen, Frank; Minh, Nhut T.; Wang, K.; Jakobsen, Henrik

    2010-11-01

    A smart fully integrated micromachined separator with soft magnetic micro-pillar arrays has been developed and demonstrated, which can merely employ one independent lab-on-chip to realize cell isolation. The simulation, design, microfabrication and test for the new electromagnetic micro separator were executed. The simulation results of the electromagnetic field in the separator show that special soft magnetic micro-pillar arrays can amplify and redistribute the electromagnetic field generated by the micro-coils. The separator can be equipped with a strong magnetic field to isolate the target cells with a considerably low input current. The micro separator was fabricated by micro-processing technology. An electroplating bath was hired to deposit NiCo/NiFe to fabricate the micro-pillar arrays. An experimental system was set up to verify the function of the micro separator by isolating the lymphocytes, in which the human whole blood mixed with Dynabeads® FlowComp Flexi and monoclonal antibody MHCD2704 was used as the sample. The results show that the electromagnetic micro separator with an extremely low input current can recognize and capture the target lymphocytes with a high efficiency, the separation ratio reaching more than 90% at a lower flow rate. For the electromagnetic micro separator, there is no external magnetizing field required, and there is no extra cooling system because there is less Joule heat generated due to the lower current. The magnetic separator is totally reusable, and it can be used to separate cells or proteins with common antigens.

  12. CryoFree Final Report

    SciTech Connect

    Burks, M

    2006-11-07

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

  13. CryoSat-2 and the CryoSat Mission

    NASA Astrophysics Data System (ADS)

    Francis, R.; Cullen, R.

    2008-12-01

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

  14. CryoSat-2 and the CryoSat Mission

    NASA Astrophysics Data System (ADS)

    Francis, R.; Cullen, R.

    2009-04-01

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

  15. A smart fully integrated micromachined separator with soft magnetic micro-pillar arrays for cell isolation

    Microsoft Academic Search

    Tao Dong; Qianhua Su; Zhaochu Yang; Yulong Zhang; Eirik B. Egeland; Dan D. Gu; Paolo Calabrese; Matteo J. Kapiris; Frank Karlsen; Nhut T. Minh; K. Wang; Henrik Jakobsen

    2010-01-01

    A smart fully integrated micromachined separator with soft magnetic micro-pillar arrays has been developed and demonstrated, which can merely employ one independent lab-on-chip to realize cell isolation. The simulation, design, microfabrication and test for the new electromagnetic micro separator were executed. The simulation results of the electromagnetic field in the separator show that special soft magnetic micro-pillar arrays can amplify

  16. Separation of reversible domain-wall motion and magnetization rotation components in susceptibility spectra of amorphous magnetic materials

    NASA Astrophysics Data System (ADS)

    Yoon, S. S.; Kim, C. G.

    2001-05-01

    The reversible susceptibility spectra are measured for rectangular Co66Fe4NiB14Si15 samples with various easy-axis angles, ?, relative to the sample axis. A phenomenological method is proposed for the reversible spectra to separate the relaxation processes of domain-wall motion and magnetization rotation. The separation provides a method for measuring the static susceptibilities and the relaxation frequencies for the two reversible magnetization processes. The ? and the longitudinal stress dependence show that the separated spectra with relaxation frequencies near 360 kHz and 1.6 MHz correspond to relaxations of domain-wall motion and to magnetization rotation, respectively.

  17. Optimum shell separation for closed axial cylindrical magnetic shields Eugene Papernoa

    E-print Network

    Paperno, Eugene

    Optimum shell separation for closed axial cylindrical magnetic shields Eugene Papernoa Department 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

  18. Studies in cryo-immunology

    PubMed Central

    Yantorno, C.; Soanes, W. A.; Gonder, M. J.; Shulman, S.

    1967-01-01

    Experimental cryosurgery has been found to result in the formation of circulating antibodies, directed against antigenic material of the tissue frozen. These antibodies were detected by passive haemagglutination and immunodiffusion. The tissue that was subjected to destructive freezing by means of this surgical procedure was the coagulating gland and seminal vesicle of rabbit. A probe carrying liquid nitrogen and a thermocouple assembly for measuring temperature changes was utilized. Control rabbits were manipulated in the same way but with no freezing. A large number of rabbits subjected to tissue freezing exhibited the development of a rapid antibody response, achieving a maximum titre in 7–10 days, followed by a decline. This antibody response has been compared to that seen following isoimmunization by injection. As an additional comparison, several rabbits were autoimmunized by injection of homogenate from their own accessory tissue; these rabbits also produced antibodies. It was found that the time sequence in the antibody production was quite similar for auto- and isoimmunization, but was quite distinctive for cryo-stimulation. By several means of evaluation, it was shown that the antibody response to the freezing of tissue was an autoantibody. It was not, however, an antibody against serum ?-globulin. The consequences of the freezing of tissue are thus seen to simulate the effects of incorporating adjuvant. This method of producing autoantibodies and investigating the nature of the response has been termed cryo-immunology. ImagesFIG. 4 PMID:4960713

  19. Element specific separation of bulk and interfacial magnetic hysteresis loops

    Microsoft Academic Search

    A. K. Suszka; C. J. Kinane; C. H. Marrows; B. J. Hickey; D. A. Arena; J. Dvorak; A. Lamperti; B. K. Tanner; S. Langridge

    2007-01-01

    We have studied the reversal of the bulk and interfacial magnetizations of the free layer of a spin valve using soft x-ray resonant magnetic scattering. By dusting the interface of the NiFe free layer with a few angströms of Co, we were able to distinguish between the interfacial and bulk magnetisms by tuning the x-ray photon energy. We measured hysteresis

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

    SciTech Connect

    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

    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

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

    NASA Astrophysics Data System (ADS)

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

    2013-12-01

    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

  2. Characterization of the physical parameters in a process of magnetic separation and pressure-driven flow of a magnetic fluid

    NASA Astrophysics Data System (ADS)

    Cunha, F. R.; Sobral, Y. D.

    2004-11-01

    The equations governing the motion of a magnetic fluid are presented. These equations are non-linear and give rise to non-Newtonian effects attributable to the magnetization of the fluid. The equations are made dimensionless and the physical parameters of the coupled hydrodynamic-magnetic problem identified. The study is first applied to describe the motion of a magnetic droplet freely suspended in a viscous fluid undergoing a permanent magnetic field. A first-order theory is developed for the regime of small drop deformation in which viscous forces dominate inertial hydrodynamic force. At this regime, it is shown that the drift velocity of a magnetic drop scales with the square of the applied magnetic field and the deformation of the drop scales linearly with the applied field. Experiments are carried out and the range of validity of the small deformation analysis determined. The pressure-driven flow of a magnetic fluid is solved by a regular asymptotic expansion for two cases: a Poiseuille flow of a single magnetic fluid and a core pipe flow with a magnetic fluid adjacent to the tube wall. The theory is used to predict the volume rate of a viscous magnetic fluid separated from a non-magnetic viscous fluid by the action of a magnetic field. The apparent viscosity of a magnetic fluid as a function of magnetic parameters is also examined from our theory. A possible application of the present theoretical studies is on the remediation technology addressed to oil spills in natural environments.

  3. Phase separation in La-Ca manganites: Magnetic field effects

    NASA Astrophysics Data System (ADS)

    Tovar, M.; Causa, M. T.; Ramos, C. A.; Laura-Ccahuana, D.

    The coexistence of magnetic phases seems to be a characteristic of the La-Ca family of in colossal magnetoresistant manganites. We have analyzed this phenomenon in terms of a free energy, F, where magnetic and electronic contributions of two coexistent phases are included. Three order parameters describe the behavior of the mixed material: the magnetization of each phase and the metallic fraction. Due to the coupling between order parameters there is a range: T**? T? T* where coexistence is possible. Values for the phenomenological parameters are obtained from the experiment. In this paper we analyze the effects of an applied magnetic field on the range of T where the phase coexistence takes place, based on results obtained from dc-magnetization and ESR measurements.

  4. Cryo-comminution of plastic waste.

    PubMed

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

    2004-01-01

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

  5. D0 Cryo CC Heater Installation

    SciTech Connect

    Urbin, J.; /Fermilab

    1991-03-16

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

  6. 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...

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

    NASA Astrophysics Data System (ADS)

    De Wulf, Marc; Anestiev, Ljubomir; Dupré, Luc; Froyen, Ludo; Melkebeek, Jan

    2002-05-01

    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 studied: (1) Pure iron powder with resin; (2) sintered iron based powders; (3) pure iron powder with additions of Zn-st and carbon; (4) iron based powder alloys (Fe,Nb,Si); (5) commercially available iron powder "Somaloy." The specimens were shaped as rectangular rods and characterized on a miniature single sheet tester which was calibrated to Epstein. The measured energy losses are analyzed following the loss separation theory of Bertotti, in which the total energy loss is decomposed into hysteresis loss, classical Foucault loss, and an excess loss component.

  8. The separated spin-charge Luttinger liquid in a magnetic field

    NASA Astrophysics Data System (ADS)

    Yang, Kaihua; Chen, Bin; Sun, Yunfeng; Han, Rushan

    As well know one-dimensional Luttinger liquid includes many striking properties. In our paper, we study the question of the physical properties of the separated spin-charge Luttinger liquid in an external magnetic field (h). We include more completely interaction such forward scattering (g 2 and g 4). Charge and spin cannot completely be separated due to the effect of magnetic field. We calculated also the correlation function and manifestly show the action of the interaction parameters.

  9. Magnetically induced phase separation and magnetic properties of Co-Mo hexagonal-close-packed structure thin films

    NASA Astrophysics Data System (ADS)

    Oikawa, K.; Qin, G. W.; Sato, M.; Kitakami, O.; Shimada, Y.; Sato, J.; Fukamichi, K.; Ishida, K.

    2003-08-01

    Magnetically induced phase separation along the Curie temperature in the hexagonal-close-packed phase of a Co-Mo binary system has been predicted by thermodynamic calculations. Furthermore, the phase separation and magnetic properties of Co-Mo sputtered thin films have been investigated. Nanoscale compositional fluctuation caused by the magnetically induced phase separation has been confirmed in the films deposited on a heated substrate in the same manner as Co-Cr-based alloys. The magnetic anisotropy constant of the Co-Mo films is larger than that of Co-Cr films. From these results, it is concluded that the Co-Mo system is promising for use as a base alloy system for high density recording media.

  10. Magnet/Syringe Separation Issues V.B. Graves

    E-print Network

    McDonald, Kirk

    of rigid pipe makes it impractical to ship and transport assembled system (syri to the syringe pump procurement. Fig. 1. Existing Design #12;2 Fig 2. Separated System Conceptual Layout to be tilted and may sit directly on the floor (or a mobile baseplate). · The syringe system no longer has

  11. Versatile fabrication of magnetic carbon fiber aerogel applied for bidirectional oil-water separation

    NASA Astrophysics Data System (ADS)

    Li, Yong; Zhu, Xiaotao; Ge, Bo; Men, Xuehu; Li, Peilong; Zhang, Zhaozhu

    2015-06-01

    Fabricating functional materials that can solve environmental problems resulting from oil or organic solvent pollution is highly desired. However, expensive materials or complicated procedures and unidirectional oil-water separation hamper their applications. Herein, a magnetic superhydrophobic carbon fiber aerogel with high absorption capacity was developed by one-step pyrolysis of Fe(NO3)3-coated cotton in an argon atmosphere. The obtained aerogel can selectively collect oils from oil-polluted region by a magnet bar owing to its magnetic properties and achieves fast oil-water separation for its superhydrophobicity and superoleophilicity. Furthermore, the aerogel performs recyclable oil absorption capacity even after ten cycles of oil-water separation and bears organic solvent immersion. Importantly, the obtained aerogel turns to superhydrophilic and underwater superoleophobic after thermal treatment, allowing it as a promising and efficient material for bidirectional oil-water separation and organic contaminants removal.

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

    PubMed

    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

    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

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

    NASA Astrophysics Data System (ADS)

    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

    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.

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

    NASA Astrophysics Data System (ADS)

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

    2004-09-01

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

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

    SciTech Connect

    Oikawa, K.; Qin, G.W.; Sato, M.; Okamoto, S.; Kitakami, O.; Shimada, Y.; Fukamichi, K.; Ishida, K.; Koyama, T. [National Institute of Advanced Industrial Science and Technology, Sendai 983-8551 (Japan); Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Sendai 980-8577 (Japan); Department of Materials Science, Graduate School of Engineering, Tohoku University, Sendai 980-8579 (Japan); National Institute for Materials Science, Ibaraki 305-0047 (Japan)

    2004-09-27

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

  16. Metalizing reduction and magnetic separation of vanadium titano-magnetite based on hot briquetting

    NASA Astrophysics Data System (ADS)

    Chen, Shuang-yin; Chu, Man-sheng

    2014-03-01

    To achieve high efficiency utilization of Panzhihua vanadium titano-magnetite, a new process of metalizing reduction and magnetic separation based on hot briquetting is proposed, and factors that affect the cold strength of the hot-briquetting products and the efficiency of reduction and magnetic separation are successively investigated through laboratory experiments. The relevant mechanisms are elucidated on the basis of microstructural observations. Experimental results show that the optimal process parameters for hot briquetting include a hot briquetting temperature of 475°C, a carbon ratio of 1.2, ore and coal particle sizes of less than 74 ?m. Additionally, with respect to metalizing reduction and magnetic separation, the rational parameters include a magnetic field intensity of 50 mT, a reduction temperature of 1350°C, a reduction time of 60 min, and a carbon ratio of 1.2. Under these above conditions, the crushing strength of the hot-briquetting agglomerates is 1480 N, and the recovery ratios of iron, vanadium, and titanium are as high as 91.19%, 61.82%, and 85.31%, respectively. The new process of metalizing reduction and magnetic separation based on hot briquetting demonstrates the evident technological advantages of high efficiency separation of iron from other valuable elements in the vanadium titano-magnetite.

  17. Removal of freshwater microalgae by a magnetic separation method

    NASA Astrophysics Data System (ADS)

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

    2013-04-01

    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.

  18. High Temperature Superconducting Reciprocating Magnetic Separator Final Report

    SciTech Connect

    James F. Maguire

    2008-06-05

    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.

  19. Simulating Chiral Magnetic and Separation Effects with Spin-Orbit Coupled Atomic Gases

    E-print Network

    Xu-Guang Huang

    2015-06-11

    The chiral magnetic and chiral separation effects---quantum-anomaly-induced electric current and axial current along an external magnetic field in parity-odd quark-gluon plasma---have received intense studies in the community of heavy-ion collision physics. We show that analogous effects occur in rotating trapped Fermi gases with Weyl-Zeeman spin-orbit coupling where the rotation plays the role of an external magnetic field. These effects can induce a mass quadrupole in the atomic cloud along the rotation axis which may be tested in future experiments. Similar effects also exist in rotating trapped Bose gases with Weyl-Zeeman spin orbit coupling. Our results suggest that the spin-orbit coupled atomic gases are potential simulators of the chiral magnetic and separation effects.

  20. Simulating Chiral Magnetic and Separation Effects with Spin-Orbit Coupled Atomic Gases

    E-print Network

    Huang, Xu-Guang

    2015-01-01

    The chiral magnetic and chiral separation effects---quantum-anomaly-induced electric current and axial current along an external magnetic field in parity-odd quark-gluon plasma---have received intense studies in the community of heavy-ion collision physics. We show that analogous effects occur in rotating trapped Fermi gases with Weyl-Zeeman spin-orbit coupling where the rotation plays the role of an external magnetic field. These effects can induce a mass quadrupole in the atomic cloud along the rotation axis which may be tested in future experiments. Similar effects also exist in rotating trapped Bose gases with Weyl-Zeeman spin orbit coupling. Our results suggest that the spin-orbit coupled atomic gases are potential simulators of the chiral magnetic and separation effects.

  1. Magnetophoresis 'meets' viscoelasticity: deterministic separation of magnetic particles in a modular microfluidic device.

    PubMed

    Del Giudice, Francesco; Madadi, Hojjat; Villone, Massimiliano M; D'Avino, Gaetano; Cusano, Angela M; Vecchione, Raffaele; Ventre, Maurizio; Maffettone, Pier Luca; Netti, Paolo A

    2015-04-21

    The deflection of magnetic beads in a microfluidic channel through magnetophoresis can be improved if the particles are somehow focused along the same streamline in the device. We design and fabricate a microfluidic device made of two modules, each one performing a unit operation. A suspension of magnetic beads in a viscoelastic medium is fed to the first module, which is a straight rectangular-shaped channel. Here, the magnetic particles are focused by exploiting fluid viscoelasticity. Such a channel is one inlet of the second module, which is a H-shaped channel, where a buffer stream is injected in the second inlet. A permanent magnet is used to displace the magnetic beads from the original to the buffer stream. Experiments with a Newtonian suspending fluid, where no focusing occurs, are carried out for comparison. When viscoelastic focusing and magnetophoresis are combined, magnetic particles can be deterministically separated from the original streamflow to the buffer, thus leading to a high deflection efficiency (up to ~96%) in a wide range of flow rates. The effect of the focusing length on the deflection of particles is also investigated. Finally, the proposed modular device is tested to separate magnetic and non-magnetic beads. PMID:25732596

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

    PubMed

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

    2013-09-01

    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

  3. A new magnetic bead-based, filterless bio-separator with planar electromagnet surfaces for integrated bio-detection systems

    Microsoft Academic Search

    Jin-Woo Choi; Chong H Ahn; Shekhar Bhansali; H. Thurman Henderson

    2000-01-01

    A new filterless bio-separator separating magnetic microbeads from a carrier fluid has been designed, fabricated, and characterized as a core component of biological cell sampling and detecting systems. To maximize the sampling capability, a planar electromagnet surface with a serpentine coil and semi-encapsulated permalloy has been realized. Using this bio-separator, antibody-coated magnetic beads have been successfully separated from the bio-buffer

  4. Efficiency comparison of two preparative mechanisms for magnetic separation of erythrocytes from whole blood

    NASA Astrophysics Data System (ADS)

    Graham, M. D.

    1981-03-01

    Separation efficiencies of erythrocytes, made paramagnetic by oxidation of their cellular oxyhemoglobin to methemoglobin with sodium nitrite, were compared under identical magnetic separation conditions with those of cells whose oxyhemoglobin had been reduced to deoxyhemoglobin through exposure to sodium dithionite, and the percentage of high-spin hemoglobin was estimated spectrophotometrically. Both parallel and transverse flow/matrix filter configurations gave greater average separation efficiencies, with less variability, for erythrocytes containing the dithionite-reduced hemoglobin. These findings are thought to originate in the characteristics of the oxidative reaction, since the spectrophotometric data indicate a similar variability in oxidation of oxyhemoglobin to methemoglobin.

  5. Transcranial Magnetic Stimulation in a Finger-tapping Task Separates Motor from Timing

    E-print Network

    Moses, Elisha

    Transcranial Magnetic Stimulation in a Finger- tapping Task Separates Motor from Timing Mechanisms,3 , and Elisha Moses1 Abstract & We study the interplay between motor programs and their timing in the brain by using precise pulses of transcranial mag- netic stimulation (TMS) applied to the primary motor cortex

  6. Two-dimensional plasma expansion in a magnetic nozzle: Separation due to electron inertia

    SciTech Connect

    Ahedo, Eduardo; Merino, Mario [Universidad Politecnica de Madrid, 28040 Madrid (Spain)

    2012-08-15

    A previous axisymmetric model of the supersonic expansion of a collisionless, hot plasma in a divergent magnetic nozzle is extended here in order to include electron-inertia effects. Up to dominant order on all components of the electron velocity, electron momentum equations still reduce to three conservation laws. Electron inertia leads to outward electron separation from the magnetic streamtubes. The progressive plasma filling of the adjacent vacuum region is consistent with electron-inertia being part of finite electron Larmor radius effects, which increase downstream and eventually demagnetize the plasma. Current ambipolarity is not fulfilled and ion separation can be either outwards or inwards of magnetic streamtubes, depending on their magnetization. Electron separation penalizes slightly the plume efficiency and is larger for plasma beams injected with large pressure gradients. An alternative nonzero electron-inertia model [E. Hooper, J. Propul. Power 9, 757 (1993)] based on cold plasmas and current ambipolarity, which predicts inwards electron separation, is discussed critically. A possible competition of the gyroviscous force with electron-inertia effects is commented briefly.

  7. Thinking out of the box for magnetic mineral separation using low temperature magnetism

    NASA Astrophysics Data System (ADS)

    Lagroix, F.; Guyodo, Y. J. B.; Till, J. L.; Taylor, S. N.

    2014-12-01

    One timeless challenge in rock magnetic studies, inclusive of paleomagnetism and environmental magnetism, is decomposing a sample's bulk magnetic behaviour into its individual magnetic mineral components. We present a method permitting to decompose the magnetic behavior of a bulk sample experimentally and at low temperature avoiding any ambiguities in data interpretation due to heating induced alteration. A single instrument is used to measure the temperature dependence of the remanent magnetization and to apply different steps of AF demagnetizations and thermal demagnetization. The experimental method is validated on synthetic mixtures of magnetite, hematite, goethite as well as on natural loess samples where the contributions of magnetite, goethite, hematite and maghemite are successfully isolated. The experimental protocol can be adapted to target other iron bearing minerals relevant to the rock or sediment under study. One limitation rests on the fact that the method is based on remanent magnetization. Consequently, a quantitative decomposition of absolute concentration of individual components remains unachievable without assumptions. Nonetheless, semi-quantitative magnetic mineral concentrations were determined on synthetic and natural loess/paleosol samples in order to validate and test the method as a semi-quantitative tool in environmental magnetism studies.

  8. Functionalization of electrospun magnetically separable TiO 2 -coated SrFe 12 O 19 nanofibers: strongly effective photocatalyst and magnetic separation

    Microsoft Academic Search

    Cong-Ju Li; Jiao-Na Wang; Xiu-Yan Li; Lian-Lian Zhang

    2011-01-01

    Magnetically separable TiO2-coated SrFe12O19 electrospun nanofibers were obtained successfully by means of sol–gel, electrospinning, and coating technology, followed\\u000a by heat treatment at 550–650 °C for 3 h. The average diameter of the electrospun fibers was 500–600 nm. The fibers were characterized\\u000a by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscope (TEM), and vibrating sample\\u000a magnetometer (VSM). The optimized calcining temperature was

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

    PubMed Central

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

    2013-01-01

    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

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

    NASA Astrophysics Data System (ADS)

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

    2011-11-01

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

  11. ?-Detected NMR Search for Magnetic Phase Separation in Epitaxial GaAs:Mn

    NASA Astrophysics Data System (ADS)

    Song, Q.; Chow, K. H.; Miller, R. I.; Fan, I.; Hossain, M. D.; Kiefl, R. F.; Morris, G. D.; Kreitzman, S. R.; Levy, C. D. P.; Parolin, T. J.; Pearson, M. R.; Salman, Z.; Saadaoui, H.; Smadella, M.; Wang, D.; Yu, K. M.; Liu, X.; Furdyna, J. K.; MacFarlane, W. A.

    To test for the microscopic magnetic phase separation in the dilute magnetic semiconductor Ga1-xMnxAs sug-gested by low energy muon spin rotation measurements[1], we present a detailed analysis of the amplitudes of the 8Li ?-detected nuclear magnetic resonance in an epitaxially grown thin film of x = 5.4% Mn doped GaAs on a semi-insulating GaAs substrate with magnetic transition temperature TC =72 K. The spectrum at 100 K corresponds to 73% of the full room temperature amplitude, and at 60 K to about 62%. The 11% loss of signal through the magnetic tran-sition is much smaller than that ? 50% found by low energy ?SR[1], and may be entirely due to an amplitude change intrinsic to GaAs. This lack of evidence for phase separation is, however, consistent with the full volume fraction magnetism found by a second low energy ?SR measurement on a different sample using weak transverse field[2].

  12. Immunomagnetic separation of Salmonella with tailored magnetic micro and nanocarriers. A comparative study.

    PubMed

    Brandão, Delfina; Liébana, Susana; Campoy, Susana; Alegret, Salvador; Isabel Pividori, María

    2015-10-01

    This paper addresses a comparative study of immunomagnetic separation of Salmonella using micro and nano-sized magnetic carriers. In this approach, nano (300nm) and micro (2.8?m) sized magnetic particles were modified with anti-Salmonella antibody to pre-concentrate the bacteria from the samples throughout an immunological reaction. The performance of the immunomagnetic separation on the different magnetic carriers was evaluated using classical culturing, confocal and scanning electron microscopy to study the binding pattern, as well as a magneto-actuated immunosensor with electrochemical read-out for the rapid detection of the bacteria in spiked milk samples. In this approach, a second polyclonal antibody labeled with peroxidase as electrochemical reporter was used. The magneto-actuated electrochemical immunosensor was able to clearly distinguish between food pathogenic bacteria such as Salmonella enterica and Escherichia coli, showing a limit of detection (LOD) as low as 538CFUmL(-1) and 291CFUmL(-1) for magnetic micro and nanocarriers, respectively, in whole milk, although magnetic nanoparticles showed a noticeable higher matrix effect and higher agglomeration effect. These LODs were achieved in a total assay time of 1h without any previous culturing pre-enrichment step. If the samples were pre-enriched for 8h, the magneto immunosensor based on the magnetic nanoparticles was able to detect as low as 1CFU in 25mL of milk (0.04CFUmL(-1)). PMID:26078149

  13. Cryo-electron microscopy of ribosomal complexes in cotranslational folding, targeting, and translocation.

    PubMed

    Knoops, Kèvin; Schoehn, Guy; Schaffitzel, Christiane

    2012-01-01

    Single-particle cryo-electron microscopy (cryo-EM) became a well-established method to study the structure and function of large macromolecular assemblies in a close to physiological environment. Cryo-EM reconstructions of ribosomal complexes trapped at different stages during translation, cotranslational targeting, and translocation provide new insights on a molecular level into these processes, which are vital for the correct localization and folding of all proteins in the cell. The EM structures in combination with biochemical experiments and available high-resolution crystal or nuclear magnetic resonance (NMR) structures of individual factors and of the ribosome allow for interpretation in quasi-atomic detail of the molecular mechanism of ribosomal complexes, their conformational changes and dynamic interactions with factors like the signal recognition particle, SRP receptor, the translocon, and the chaperone trigger factor. The snapshots obtained by single-particle EM reconstructions enable us to follow the path of a nascent protein from the peptidyl-transferase center, through the ribosomal tunnel, to and across the translocon in the membrane. With new developments in image processing techniques it is possible to sort a biological homogenous sample into different conformational states and to reach subnanometer resolution such that folding of the nascent chain into secondary structure elements can be directly visualized. With improved cryo-electron tomography and correlative light microscopy and EM, it will be possible to visualize ribosomal complexes in their cellular context. PMID:22095783

  14. A comparative analysis of the cryo-compression and cryo-adsorption hydrogen storage methods

    SciTech Connect

    Petitpas, G [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Benard, P [Universite du Quebec a Trois-Rivieres (Canada); Klebanoff, L E [Sandia National Lab. (SNL-CA), Livermore, CA (United States); Xiao, J [Universite du Quebec a Trois-Rivieres (Canada); Aceves, S M [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2014-07-01

    While conventional low-pressure LH? dewars have existed for decades, advanced methods of cryogenic hydrogen storage have recently been developed. These advanced methods are cryo-compression and cryo-adsorption hydrogen storage, which operate best in the temperature range 30–100 K. We present a comparative analysis of both approaches for cryogenic hydrogen storage, examining how pressure and/or sorbent materials are used to effectively increase onboard H? density and dormancy. We start by reviewing some basic aspects of LH? properties and conventional means of storing it. From there we describe the cryo-compression and cryo-adsorption hydrogen storage methods, and then explore the relationship between them, clarifying the materials science and physics of the two approaches in trying to solve the same hydrogen storage task (~5–8 kg H?, typical of light duty vehicles). Assuming that the balance of plant and the available volume for the storage system in the vehicle are identical for both approaches, the comparison focuses on how the respective storage capacities, vessel weight and dormancy vary as a function of temperature, pressure and type of cryo-adsorption material (especially, powder MOF-5 and MIL-101). By performing a comparative analysis, we clarify the science of each approach individually, identify the regimes where the attributes of each can be maximized, elucidate the properties of these systems during refueling, and probe the possible benefits of a combined “hybrid” system with both cryo-adsorption and cryo-compression phenomena operating at the same time. In addition the relationships found between onboard H? capacity, pressure vessel and/or sorbent mass and dormancy as a function of rated pressure, type of sorbent material and fueling conditions are useful as general designing guidelines in future engineering efforts using these two hydrogen storage approaches.

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

    SciTech Connect

    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)

    2013-01-01

    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.

  16. A simple and rapid harvesting method for microalgae by in situ magnetic separation.

    PubMed

    Xu, Ling; Guo, Chen; Wang, Feng; Zheng, Sen; Liu, Chun-Zhao

    2011-11-01

    A simple and rapid harvesting method by in situ magnetic separation with naked Fe(3)O(4) nanoparticles has been developed for the microalgal recovery of Botryococcus braunii and Chlorella ellipsoidea. After adding the magnetic particles to the microalgal culture broth, the microalgal cells were adsorbed and then separated by an external magnetic field. The maximal recovery efficiency reached more than 98% for both microalgae at a stirring speed of 120 r/min within 1 min, and the maximal adsorption capacity of these Fe(3)O(4) nanoparticles reached 55.9 mg-dry biomass/mg-particles for B. braunii and 5.83 mg-dry biomass/mg-particles for C. ellipsoidea. Appropriate pH value and high nanoparticle dose were favorable to the microalgae recovery, and the adsorption mechanism between the naked Fe(3)O(4) nanoparticles and the microalgal cells was mainly due to the electrostatic attraction. The developed in situ magnetic separation technology provides a great potential for saving time and energy associated with improving microalgal harvesting. PMID:21890346

  17. The CryoCapsule: Simplifying correlative light to electron microscopy

    PubMed Central

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

    2014-01-01

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

  18. The CryoCapsule: simplifying correlative light to electron microscopy.

    PubMed

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

    2014-06-01

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

  19. Mechanical and Electrical Properties of Cryo-worked Cu

    NASA Astrophysics Data System (ADS)

    Bettinali, Livio; Tosti, Silvano; Pizzuto, Aldo

    2014-01-01

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

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

    PubMed

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

    2012-07-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2014-06-01

    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.

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

    SciTech Connect

    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

    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.

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

    PubMed

    Schorb, Martin; Briggs, John A G

    2014-08-01

    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

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

    PubMed

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

    2013-10-01

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

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

    PubMed

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

    2007-01-01

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

  6. Temperature-Switchable Agglomeration of Magnetic Particles Designed for Continuous Separation Processes in Biotechnology.

    PubMed

    Paulus, Anja S; Heinzler, Raphael; Ooi, Huey Wen; Franzreb, Matthias

    2015-07-01

    The purpose of this work was the synthesis and characterization of thermally switchable magnetic particles for use in biotechnological applications such as protein purification and enzymatic conversions. Reversible addition-fragmentation chain-transfer polymerization was employed to synthesize poly(N-isopropylacrylamide) brushes via a "graft-from" approach on the surface of magnetic microparticles. The resulting particles were characterized by infrared spectroscopy and thermogravimetric analysis and their temperature-dependent agglomeration behavior was assessed. The influence of several factors on particle agglomeration (pH, temperature, salt type, and particle concentration) was evaluated. The results showed that a low pH value (pH 3-4), a kosmotropic salt (ammonium sulfate), and a high particle concentration (4 g/L) resulted in improved agglomeration at elevated temperature (40 °C). Recycling of particles and reversibility of the temperature-switchable agglomeration were successfully demonstrated for ten heating-cooling cycles. Additionally, enhanced magnetic separation was observed for the modified particles. Ionic monomers were integrated into the polymer chain to create end-group functionalized particles as well as two- and three-block copolymer particles for protein binding. The adsorption of lactoferrin, bovine serum albumin, and lysozyme to these ion exchange particles was evaluated and showed a binding capacity of up to 135 mg/g. The dual-responsive particles combined magnetic and thermoresponsive properties for switchable agglomeration, easy separability, and efficient protein adsorption. PMID:26069936

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

    SciTech Connect

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

    2000-11-01

    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.

  8. 2D modeling and preliminary in vitro investigation of a prototype high gradient magnetic separator for biomedical applications.

    PubMed

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

    2008-01-01

    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

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

    NASA Astrophysics Data System (ADS)

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

    2013-03-01

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

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

    PubMed

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

    2014-02-15

    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

  11. Accessible and green manufacturing of magnetite (ferrous ferric oxide) nanocrystals and their use in magnetic separations

    NASA Astrophysics Data System (ADS)

    Yavuz, Cafer Tayyar

    This work describes the first size dependent magnetic separation in nanoscale. Magnetite (Fe3O4) nanocrystals of high quality and uniform size were synthesized with monodispersity below 10%. Magnetite nanocrystals of 4 nm to 33 nm (average diameter) were produced. Batch synthesis was shown to go up to 20 grams which is more than 10 times of a standard nanocrystal synthesis, without loosing the quality and monodispersity. Reactor design for mass (1 gram per hour) production of magnetite nanocrystals is reported for the first time. The cost of a kg of lab purity magnetite nanocrystals was shown to be 2600. A green synthesis that utilizes rust and edible oils was developed. The cost of a kg was brought down to 22. Size dependency of magnetism was shown in nanoscale for the first time. Reversible aggregation theory was developed to explain the low field magnetic separation and solution behavior of magnetite nanocrystals. Arsenic was removed from drinking water with magnetite nanocrystals 200 times better than commercial adsorbents. Silica coating was successfully applied to enable the known silica related biotechnologies. Magnetite-silica nanoshells were functionalized with amino groups. For the first time, silver was coated on the magnetite-silica nanoshells to produce triple multishells. Anti-microbial activity of multishells is anticipated.

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

    PubMed

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

    2007-09-01

    A portable separator has been developed to quantitatively separate blood-borne magnetic spheres in potentially high-flow regimes for the human detoxification purpose. In the separator design, an array of biocompatible capillary tubing and magnetizable wires is immersed in an external magnetic field that is generated by two permanent magnets. The wires are magnetized and the high magnetic field gradient from the magnetized wires helps to collect blood-borne magnetic nano/micro-spheres from the blood flow. In this study, a 3D numerical model was created and the effect of tubing-wire configurations on the capture efficiency of the system was analyzed using COMSOL Multiphysics 3.3(R). The results showed that the configuration characterized by bi-directionally alternating wires and tubes was the best design with respect to the four starting configurations. Preliminary in vitro experiments verified the numerical predictions. The results helped us to optimize a prototype portable magnetic separator that is suitable for rapid sequestration of magnetic nano/micro-spheres from the human blood stream while accommodating necessary clinical boundary conditions. PMID:17762081

  13. An integrated open-cavity system for magnetic bead separation and manipulation.

    PubMed

    Abu-Nimeh, Faisal T; Salem, Fathi M

    2011-01-01

    Superparamagnetic beads are generally used in biomedical assays to manipulate, maneuver, separate, and transport bio-materials. We present a low-cost integrated system designed in bulk 0.5 ?m process to automate the manipulation and separation process of magnetic beads. The system consists of an 8 × 8 coil-array suitable for a single bead manipulation, or collaborative manipulation using pseudoparallel executions. The size of a single coil is 30 ?m × 30 ?m and the driver DC current source supports 8 different levels up to 1.5 mA. The total power consumption of the entire system is 9 mW when running at full power and it occupies an area of 248 ?m × 248 ?m. PMID:22256293

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

    PubMed Central

    2012-01-01

    Thiol group functionalized silica-coated magnetic nanoparticles (Si-MNPs@SH) were synthesized for rapid and selective magnetic field-based separation of mixed proteins. The highest adsorption efficiencies of binary proteins, bovine serum albumin (BSA; 66 kDa; pI = 4.65) and lysozyme (LYZ; 14.3 kDa; pI = 11) were shown at the pH values corresponding to their own pI in the single-component protein. In the mixed protein, however, the adsorption performance of BSA and LYZ by Si-MNPs@SH was governed not only by pH but also by the molecular weight of each protein in the mixed protein. PMID:22650609

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

    NASA Astrophysics Data System (ADS)

    Kusakabe, Motohiko; Kawasaki, Masahiro

    2015-01-01

    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.

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

    PubMed Central

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

    2009-01-01

    Optical observations of 100 nm metallic magnetic nanoparticles are used to study their magnetic field induced self assembly. Chains with lengths of tens of microns are observed to form within minutes at nanoparticle concentrations of 1010 per mL. Chain rotation and magnetophoresis are readily observed, and SEM reveals that long chains are not simple single particle filaments. Similar chains are detected for several 100 nm commercial bio-separation nanoparticles. We demonstrate the staged magnetic condensation of different types of nanoparticles into composite structures and show that magnetic chains bind to immunomagnetically labeled cells, serving as temporary handles which allow novel magnetic cell manipulations. PMID:20161001

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

    Microsoft Academic Search

    R. R. Judkins; T. D. Burchell

    1999-01-01

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

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

    Microsoft Academic Search

    Roddie R. Judkins; Timothy D. Burchell

    1999-01-01

    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 \\

  19. 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...

  20. 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...

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

    DOEpatents

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

    1999-07-20

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

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

    DOEpatents

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

    1999-01-01

    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.

  3. Inhomogeneous Magnetism in Single Crystalline Sr3CuIrO6+delta: Implications to Phase-Separation Concepts

    Microsoft Academic Search

    Asad Niazi; P. L. Paulose; E. V. Sampathkumaran

    2002-01-01

    The single crystalline form of an insulator, Sr3CuIrO6+delta, is shown to exhibit unexpectedly more than one magnetic transition (at 5 and 19 K) with spin-glass-like magnetic susceptibility behavior. On the basis of this finding, viz., inhomogeneous magnetism in a chemically homogeneous material, we propose that the idea of ``phase separation'' described for manganites is more widespread in different ways. The

  4. Colouring cryo-cooled crystals: online microspectrophotometry

    PubMed Central

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

    2009-01-01

    X-rays can produce a high concentration of radicals within cryo-cooled macromolecular crystals. Some radicals have large extinction coefficients in the visible (VIS) range of the electromagnetic spectrum, and can be observed optically and spectrally. An online microspectrophotometer with high temporal resolution has been constructed that is capable of measuring UV/VIS absorption spectra (200–1100?nm) during X-ray data collection. The typical X-ray-induced blue colour that is characteristic of a wide range of cryo-conditions has been identified as trapped solvated electrons. Disulphide-containing proteins are shown to form disulphide radicals at millimolar concentrations, with absorption maxima around 400?nm. The solvated electrons and the disulphide radicals seem to have a lifetime in the range of seconds up to minutes at 100?K. The temperature dependence of the kinetics of X-ray-induced radical formation is different for the solvated electrons compared with the disulphide radicals. The online microspectrophotometer provides a technique complementary to X-ray diffraction for analysing and characterizing intermediates and redox states of proteins and enzymes. PMID:19240328

  5. Spectral functions in a magnetic field as a probe of spin-charge separation in a Luttinger liquid

    E-print Network

    Silvio Rabello; Qimiao Si

    2003-02-07

    We show that the single-particle spectral functions in a magnetic field can be used to probe spin-charge separation of a Luttinger liquid. Away from the Fermi momentum, the magnetic field splits both the spinon peak and holon peak; here the spin-charge separation nature is reflected in the different magnitude of the two splittings. At the Fermi momentum, the magnetic field splits the zero-field peak into {\\it four} peaks. The feasibility of experimentally studying this effect is discussed.

  6. Spectral functions in a magnetic field as a probe of spin-charge separation in a Luttinger liquid

    NASA Astrophysics Data System (ADS)

    Rabello, Silvio; Si, Qimiao

    2000-10-01

    We show that the single-particle spectral functions in a magnetic field can be used to probe spin-charge separation of a Luttinger liquid. Away from the Fermi momentum, the magnetic field splits both the spinon peak and holon peak; here the spin-charge separation nature is reflected in the different magnitude of the two splittings. At the Fermi momentum, the magnetic field splits the zero-field peak into four. The feasibility of studying this effect using angle-resolved photoemission and momentum-resolved tunneling is discussed.

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

    NASA Astrophysics Data System (ADS)

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

    2010-11-01

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

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

    PubMed

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

    2013-01-01

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

  9. CryoSat: ready to launch (again)

    NASA Astrophysics Data System (ADS)

    Francis, R.; Wingham, D.; Cullen, R.

    2009-12-01

    Over the last ten years the relationship between climate change and the cryosphere has become increasingly important. Evidence of change in the polar regions is widespread, and the subject of public discussion. During this same ten years ESA has been preparing its CryoSat mission, specifically designed to provide measurements to determine the overall change in the mass balance of all of the ice caps and of change in the volume of sea-ice (rather than simply its extent). In fact the mission was ready for launch in October 2005, but a failure in the launch vehicle led to a loss of the satellite some 6 minutes after launch. The determination to rebuild the satellite and complete the mission was widespread in the relevant scientific, industrial and political entities, and the decision to redirect financial resources to the rebuild was sealed with a scientific report confirming that the mission was even more important in 2005 than at its original selection in 1999. The evolution of the cryosphere since then has emphasised that conclusion. In order to make a meaningful measurement of the secular change of the surface legation of ice caps and the thickness of sea-ice, the accuracy required has been specified as about half of the variation expected due to natural variability, over reasonable scales for the surfaces concerned. The selected technique is radar altimetry. Previous altimeter missions have pioneered the method: the CryoSat instrument has been modified to provide the enhanced capabilities needed to significantly extend the spatial coverage of these earlier missions. Thus the radar includes a synthetic aperture mode which enables the along-track resolution to be improved to about 250 m. This will will allow detection of leads in sea-ice which are narrower than those detected hitherto, so that operation deeper into pack-ice can be achieved with a consequent reduction in errors due to omission. Altimetry over the steep edges of ice caps is hampered by the irregular topography which, since the radar ranging is performed to the closest reflector rather than the point directly below, introduces uncertainty into the exactitude of repeat measurements. CryoSat's radar includes a second antenna and receiver chain so that interferometry may be used to determine the arrival angle of the echo and so improve localisation of the reflection. The new satellite was approved in late February 2006, less than 6 months after the failure, and development started almost immediately. In September 2009 the development was completed and the satellite placed into storage awaiting a launch vehicle: the launch, using a Dnepr vehicle (a converted SS-18 ICBM) is anticipated in late February 2010.

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

    NASA Astrophysics Data System (ADS)

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

    2011-05-01

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

  11. Magnetism of perovskite oxides: The effect of strain and phase separation

    NASA Astrophysics Data System (ADS)

    Xie, Changkun

    The magnetic properties of perovskite oxides can be affected by various conditions such as doping concentration, finite size limitation, and mechanical strain, which are associated with a range of intriguing physical phenomena in highly correlated electron systems such as colossal magnetoresistance, high temperature superconductivity, and phase inhomogeneities. In this thesis, we studied several topics concerning the cobaltates and nickelates which are associated with magnetism in perovskite oxides. La0.5Sr0.5CoO3 is a ferromagnetic material with Curie temperature TC of 250 K. In a form of thin films, we studied strain effect on its ferromagnetism. However, ferromagnetism in thin films is affected by both finite size effect and strain effect. We have used a series of films of different thicknesses and on different substrates to quantitatively determine the change in TC contributed by each effect. The phase diagram of TC versus in-plane strain suggests that TC is suppressed by tensile strain and enhanced by compressive strain. The general method of separating strain and finite thickness effects should be applicable to any ordering phase transition in thin films. The local structure of LSCO thin films was investigated by Extended X-ray Absorption Fine Structure technique. Our results suggest that the tensile strain elongates the Co-O bond length, while compressive strain shortens the bond length. The change of bond length is mainly responsible for the modulation of TC upon strain. This is contrary to assumptions generally used in literature on strained manganite films. Current double exchange model is not adequate to describe the ferromagnetic mechanism for cobaltate. In a case of no La, we studied the magnetic properties of SrCoO 2.5+x. SrCoO2.5 is an antiferromaget with Neel temperature of 570 K. With a starting material of SrCoO 2.88, we have carried out oxidization and reduction experiments through an electrochemical method. The hole doping introduced into SrCoO2.5 by oxygen has shown to play a crucial role in determining the materials' ferromagnetic characters such as Curie temperature, spin state, magnetic saturation moment, etc. A magnetic phase diagram of SrCoO2.5+x is thus proposed for the first time. The striking feature of the diagram is the existence of several line phases which contain antiferromagnetic and ferromagnetic phases. In high contrast with La1-ySryCoO 3, SrCoO2.5+x can be phase separated into a number of magnetic regions for which each one has a unique oxygen/hole concentration such as x = 0, 0.25, 0.375, and 0.5, respectively. Our results suggest that the mobile holes are playing a key role in ferromagnetism and phase separation in the system. For perovskite nickelate, we have successfully grown high-quality epitaxial La1.67Sr0.33NiO4 films using pulsed laser deposition. For the first time, the x-ray diffraction superlattice peaks associated with charge stripe phase have been successfully observed in films. By studying the evolution of the stripe phase as the film thicknesses are decreased, we provide direct evidence for suppression of the stripe phase in thinner samples with thicknesses of less than 2600 A. A scenario of short-range ordered stripes due to a lattice clamping effect is proposed to account for the suppression in light of a model of electronic stripe-glass.

  12. Blind Source Separation of Hemodynamics from Magnetic Resonance Perfusion Brain Images Using Independent Factor Analysis

    PubMed Central

    Chou, Yen-Chun; Lu, Chia-Feng; Guo, Wan-Yuo; Wu, Yu-Te

    2010-01-01

    Perfusion magnetic resonance brain imaging induces temporal signal changes on brain tissues, manifesting distinct blood-supply patterns for the profound analysis of cerebral hemodynamics. We employed independent factor analysis to blindly separate such dynamic images into different maps, that is, artery, gray matter, white matter, vein and sinus, and choroid plexus, in conjunction with corresponding signal-time curves. The averaged signal-time curve on the segmented arterial area was further used to calculate the relative cerebral blood volume (rCBV), relative cerebral blood flow (rCBF), and mean transit time (MTT). The averaged ratios for rCBV, rCBF, and MTT between gray and white matters for normal subjects were congruent with those in the literature. PMID:20445739

  13. Cerebral venous and arterial blood volumes can be estimated separately in humans using magnetic resonance imaging.

    PubMed

    An, Hongyu; Lin, Weili

    2002-10-01

    Approaches to obtain quantitative, noninvasive estimates of total cerebral blood volume (tCBV) and cerebral venous blood volume (vCBV) separately in humans are proposed. Two sequences were utilized, including a 3D high-resolution gradient-echo (GE) sequence and a 2D multi-echo GE/spin-echo (MEGESE) sequence. Images acquired by the former sequence provided an estimate of background magnetic field variations (DeltaB), while images obtained by the latter sequence were utilized to obtain separate measures of tCBV and vCBV with and without contrast agent. Prior to the calculation of vCBV and tCBV, the acquired images were corrected for signal loss induced by the presence of DeltaB. vCBV and tCBV were estimated to be 2.46% +/- 0.28% and 3.20% +/- 0.41%, respectively, after the DeltaB correction, which in turn provided a vCBV/tCBV ratio of 0.77 +/- 0.04, in excellent agreement with results reported in the literature. Our results demonstrate that quantitative estimates of vCBV and tCBV can be obtained in vivo. PMID:12353273

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

    NASA Astrophysics Data System (ADS)

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

    2012-12-01

    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.

  15. Cryogenics for Pulsed Solenoid Magnet

    E-print Network

    McDonald, Kirk

    Committee September 6, 2002 G. T Mulholland ACT World Headquarters Applied Cryogenics Technology PO Box 2158, Peter Titus Magnet Design: Bob Weggel Cryo-Design Issues: ACT, G. T. Mulholland Components 1). Pulsed

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

    PubMed Central

    2010-01-01

    Background Highly purified infected red blood cells (irbc), or highly synchronized parasite cultures, are regularly required in malaria research. Conventional isolation and synchronization rely on density and osmotic fragility of irbc, respectively. High gradient magnetic separation (HGMS) offers an alternative based on intrinsic magnetic properties of irbc, avoiding exposure to chemicals and osmotic stress. Successful HGMS concentration in malaria research was previously reported using polymer coated columns, while HGMS depletion has not been described yet. This study presents a new approach to both HGMS concentration and depletion in malaria research, rendering polymer coating unnecessary. Methods A dipole magnet generating a strong homogenous field was custom assembled. Polypropylene syringes were fitted with one-way stopcocks and filled with stainless steel wool. Rbc from Plasmodium falciparum cultures were resuspended in density and viscosity optimized HGMS buffers and HGMS processed. Purification and depletion results were analysed by flow cytometer and light microscopy. Viability was evaluated by calculating the infection rate after re-culturing of isolates. Results In HGMS concentration, purity of irbc isolates from asynchronous cultures consistently ranged from 94.8% to 98.4% (mean 95.7%). With further optimization, over 90% of isolated irbc contained segmented schizonts. Processing time was less than 45 min. Reinfection rates ranged from 21.0% to 56.4%. In HGMS depletion, results were comparable to treatment with sorbitol, as demonstrated by essentially identical development of cultures. Conclusion The novel HGMS concentration procedure achieves high purities of segmented stage irbc from standard asynchronous cultures, and is the first HGMS depletion alternative to sorbitol lysis. It represents a simple and highly efficient alternative to conventional irbc concentration and synchronization methods. PMID:20122252

  17. Fabrication of chiral amino acid ionic liquid modified magnetic multifunctional nanospheres for centrifugal chiral chromatography separation of racemates.

    PubMed

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

    2015-06-26

    As the rapid development of nanotechnology, the magnetic nanospheres modified with special chiral selective ligands show a great potentiality in enantiomeric separation. In this study, magnetic nanospheres modified with task-specific chiral ionic liquid were designed for the separation of chiral amino acids. These modified magnetic nanospheres were effective in a direct chiral separation of five racemic amino acids (d- and l-cysteine, d- and l-arginine, d- and l-leucine, d- and l-glutamine and d- and l-tryptophan). Furthermore, a new online method for complete separation of the enantiomers via the magnetic nanospheres was established with centrifugal chiral chromatography using a spiral tube assembly mounted on a type-J coil planet centrifuge. One kind of chiral compounds, d- and l-tryptophan was resolved well using this method. These results demonstrated that the modified nanospheres display a good chiral recognition ability, and can be used as a potential material for chiral separation of various racemates. PMID:25976126

  18. Preliminary results of pre-combustion removal of mercury, arsenic, and selenium from coal by dry magnetic separation

    SciTech Connect

    Oder, R.R.; Jamison, R.E.; Brandner, E.D.

    1999-07-01

    The authors report the results of preliminary measurements of pre-combustion separation of major metal oxides and trace elements from coal by dry magnetic separation. The measurements have been made as part of ETCi's development of MagMill{trademark} technology for removing mineral matter from coal at the pulverizer at the front end of a coal fired power plant. The technology is specific to separation of mercury, arsenic, and selenium because of their associations with iron pyrites in coal. Measurements were made on a suite of five Eastern US and five Illinois Basin bituminous rank coals prepared at 8 Mesh topsize and processed as 8 Mesh by zero fractions through a dry Para Trap Magnetic Separator. Measurements of major metals and trace elements were made on the feed coal, the magnetic refuse fraction and the magnetic clean coal product. The range of weight recoveries measured for 13 of the trace elements for the suite of coals indicates a significant potential for pre-combustion removal of trace elements and especially for mercury, selenium, and arsenic by dry magnetic methods. While these three elements are important because they are considered hazardous air pollutant precursors, pre-combustion removal of arsenic is especially important because of its role in poisoning catalysts used in emerging SO{sub x} and NO{sub x} control technologies.

  19. Collaborative Computational Project for Electron cryo-Microscopy

    SciTech Connect

    Wood, Chris; Burnley, Tom [Science and Technology Facilities Council, Research Complex at Harwell, Didcot OX11 0FA (United Kingdom); Patwardhan, Ardan [European Molecular Biology Laboratory, Wellcome Trust Genome Campus, Hinxton, Cambridge CB10 1SD (United Kingdom); Scheres, Sjors [MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge Biomedical Campus, Cambridge CB2 0QH (United Kingdom); Topf, Maya [University of London, Malet Street, London WC1E 7HX (United Kingdom); Roseman, Alan [University of Manchester, Oxford Road, Manchester M13 9PT (United Kingdom); Winn, Martyn, E-mail: martyn.winn@stfc.ac.uk [Science and Technology Facilities Council, Daresbury Laboratory, Warrington WA4 4AD (United Kingdom); Science and Technology Facilities Council, Research Complex at Harwell, Didcot OX11 0FA (United Kingdom)

    2015-01-01

    The Collaborative Computational Project for Electron cryo-Microscopy (CCP-EM) is a new initiative for the structural biology community, following the success of CCP4 for macromolecular crystallography. Progress in supporting the users and developers of cryoEM software is reported. 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.

  20. CryoWEB: Web software for the documentation of the cryo-preserved material in animal gene banks

    PubMed Central

    Duchev, Zhivko; Cong, Truong Van Chi; Groeneveld, Eildert

    2010-01-01

    Many countries in the world have set up national domestic conservation programmes and collections of long-term storage of cryo-preserved animal genetic material. We have developed a web based software ? CryoWEB for the documentation of such collections. The software is generally applicable to all livestock breeds, independent of the donor's species and the type of preserved material. The software can record basic herd?book information for the donor animal, the structure of the storage facilities, description of the stored samples and their distribution within the gene bank. It also traces the movements of the sample vessels within the storage facilities and the usage of sample units. The outputs implemented in CryoWEB address the informational needs of the gene bank manager in her everyday tasks. Availability CryoWEB is publicly available athttp://cryoweb.tzv.fal.de PMID:21364801

  1. Zernike Phase Contrast Cryo-Electron Microscopy and Tomography for Structure Determination at Nanometer and Subnanometer Resolutions

    E-print Network

    Murata, Kazuyoshi

    Zernike phase contrast cryo-electron microscopy (ZPC-cryoEM) is an emerging technique that is capable of producing higher image contrast than conventional cryoEM. By combining this technique with advanced image processing ...

  2. 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...

  3. Magnetic Structure and Phase Separation in Epitaxial SrCoOx Thin Films

    NASA Astrophysics Data System (ADS)

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

    2013-03-01

    Bulk SrCoOx separates into three distinct ferromagnetic phases as the oxygen content is increased from x = 2.75 to 3.0, corresponding to TC = 165 K (SrCoO2.75) , TC = 220 K (SrCoO2.88) , and TC = 280 K (SrCoO3.0) . Over this composition, the lattice evolves smoothly and remains a single crystallographic phase. Using pulsed laser deposition and electrochemical oxidation, we have prepared epitaxial films of SrCoOx of varying thickness and orientation on SiTiO3 substrates. While in polycrystalline samples intermediate oxygen concentrations show a two-phase magnetic behavior, 100nm thick (0 0 1) films remain single phase but still favor the same ferromagnetic transitions. Thicker, 150 nm (1 1 1) films also order at comparable TC's, but again show two-phase behavior during deoxidation. Resonant x-ray diffraction on these samples reveals both commensurate and incommensurate ordering dependent on the oxidation state. This implies a charge or orbital ordering which may be influenced by finite size effects. Bulk SrCoOx separates into three distinct ferromagnetic phases as the oxygen content is increased from x = 2.75 to 3.0, corresponding to TC = 165 K (SrCoO2.75) , TC = 220 K (SrCoO2.88) , and TC = 280 K (SrCoO3.0) . Over this composition, the lattice evolves smoothly and remains a single crystallographic phase. Using pulsed laser deposition and electrochemical oxidation, we have prepared epitaxial films of SrCoOx of varying thickness and orientation on SiTiO3 substrates. While in polycrystalline samples intermediate oxygen concentrations show a two-phase magnetic behavior, 100nm thick (0 0 1) films remain single phase but still favor the same ferromagnetic transitions. Thicker, 150 nm (1 1 1) films also order at comparable TC's, but again show two-phase behavior during deoxidation. Resonant x-ray diffraction on these samples reveals both commensurate and incommensurate ordering dependent on the oxidation state. This implies a charge or orbital ordering which may be influenced by finite size effects. The work is supported by the NSF through contract # DMR-0907197 (UConn) and DMR-0706610 (NIU). Research at the CLS is supported by NSERC, NRC, CIHR, Prov. of Sask., WD Canada, and U. Saskatchewan.

  4. Ground validation of CryoSat-2 on Austfonna, Svalbard

    NASA Astrophysics Data System (ADS)

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

    2012-12-01

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

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

    PubMed

    Kapcia, Konrad; Robaszkiewicz, Stanis?aw

    2013-02-13

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

  6. Improvement of a High-Gradient Magnetic Separation System for Trapping Immunoglobulin in Serum

    Microsoft Academic Search

    Hiroshi Ueda; Koh Agatsuma; Shuichiro Fuchino; Tomohiro Imura; Mitsuho Furuse; Kazuhiro Kajikawa; Atsushi Ishiyama; Tatsuo Koizumi; Shinichiro Miyake

    2010-01-01

    Recently, affinity magnetic beads have been widely used in immunomagnetic cell sorting (IMCS) technology. Today, we can easily sort and analyse DNA and antibodies (immunoglobulin) using various types of affinity magnetic beads available in the market. The diameters of the affinity magnetic beads used in immunomagnetic cell sorting are above approximately 1 ??m because of the low magnetic fields induced

  7. Cryo-EM structure of a 3D DNA-origami object Xiao-chen Baia

    E-print Network

    Dietz, Hendrik

    solutions free from nucleic acid stains and gel matrix residues (Fig. S2). Cryo-EM Single-Particle Analysis object was designed to be suitable for structure determination by cryo-EM single- particle analysis

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

    NASA Astrophysics Data System (ADS)

    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

    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.

  9. 76 FR 4338 - Research and Development Strategies for Compressed & Cryo-Compressed Hydrogen Storage Workshops

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-01-25

    ...associated with performance and reliability of cryogenic hydrogen storage systems, including cryo-compressed and cryo-adsorption systems. The objective is to determine and prioritize the research needs and technical pathways for each approach while...

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

    NASA Astrophysics Data System (ADS)

    Mayo, John Thomas

    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.

  11. Progressive Stochastic Reconstruction Technique (PSRT) for cryo electron tomography.

    PubMed

    Turo?ová, Beata; Marsalek, Lukas; Davidovi?, Tomáš; Slusallek, Philipp

    2015-03-01

    Cryo Electron Tomography (cryoET) plays an essential role in Structural Biology, as it is the only technique that allows to study the structure of large macromolecular complexes in their close to native environment in situ. The reconstruction methods currently in use, such as Weighted Back Projection (WBP) or Simultaneous Iterative Reconstruction Technique (SIRT), deliver noisy and low-contrast reconstructions, which complicates the application of high-resolution protocols, such as Subtomogram Averaging (SA). We propose a Progressive Stochastic Reconstruction Technique (PSRT) - a novel iterative approach to tomographic reconstruction in cryoET based on Monte Carlo random walks guided by Metropolis-Hastings sampling strategy. We design a progressive reconstruction scheme to suit the conditions present in cryoET and apply it successfully to reconstructions of macromolecular complexes from both synthetic and experimental datasets. We show how to integrate PSRT into SA, where it provides an elegant solution to the region-of-interest problem and delivers high-contrast reconstructions that significantly improve template-based localization without any loss of high-resolution structural information. Furthermore, the locality of SA is exploited to design an importance sampling scheme which significantly speeds up the otherwise slow Monte Carlo approach. Finally, we design a new memory efficient solution for the specimen-level interior problem of cryoET, removing all associated artifacts. PMID:25659894

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

    NASA Technical Reports Server (NTRS)

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

    1978-01-01

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

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

    SciTech Connect

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

    1997-01-01

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

  14. Monitoring the Stability of Perfluorocarbon Nanoemulsions by Cryo-TEM Image Analysis and Dynamic Light Scattering

    PubMed Central

    Grapentin, Christoph; Barnert, Sabine; Schubert, Rolf

    2015-01-01

    Perfluorocarbon nanoemulsions (PFC-NE) are disperse systems consisting of nanoscale liquid perfluorocarbon droplets stabilized by an emulsifier, usually phospholipids. Perfluorocarbons are chemically inert and non-toxic substances that are exhaled after in vivo administration. The manufacture of PFC-NE can be done in large scales by means of high pressure homogenization or microfluidization. Originally investigated as oxygen carriers for cases of severe blood loss, their application nowadays is more focused on using them as marker agents in 19F Magnetic Resonance Imaging (19F MRI). 19F is scarce in organisms and thus PFC-NE are a promising tool for highly specific and non-invasive imaging of inflammation via 19F MRI. Neutrophils, monocytes and macrophages phagocytize PFC-NE and subsequently migrate to inflamed tissues. This technique has proven feasibility in numerous disease models in mice, rabbits and mini pigs. The translation to clinical trials in human needs the development of a stable nanoemulsion whose droplet size is well characterized over a long storage time. Usually dynamic light scattering (DLS) is applied as the standard method for determining particle sizes in the nanometer range. Our study uses a second method, analysis of transmission electron microscopy images of cryo-fixed samples (Cryo-TEM), to evaluate stability of PFC-NE in comparison to DLS. Four nanoemulsions of different composition are observed for one year. The results indicate that DLS alone cannot reveal the changes in particle size, but can even mislead to a positive estimation of stability. The combination with Cryo-TEM images gives more insight in the particulate evolution, both techniques supporting one another. The study is one further step in the development of analytical tools for the evaluation of a clinically applicable perfluorooctylbromide nanoemulsion. PMID:26098661

  15. Imaging Drosophila brain by combining cryo-soft X-ray microscopy of thick vitreous sections and cryo-electron microscopy of ultrathin vitreous sections.

    PubMed

    Leforestier, Amélie; Levitz, Pierre; Preat, Thomas; Guttmann, Peter; Michot, Laurent J; Tchénio, Paul

    2014-11-01

    Cryo-soft X-ray microscopy is an emerging imaging tool complementary to cryo-electron microscopy, allowing to image frozen hydrated specimens ten to hundred times thicker, but at lower resolution. We describe how the method, so far restricted to isolated small cells or cell monolayers, can be extended to large cells and tissue. We image the synapses of the Kenyon cells in frozen hydrated Drosophila brains combining cryo-soft X-ray microscopy of thick vitreous sections, and cryo-electron microscopy of ultrathin vitreous sections. We show how to obtain frozen hydrated sections of thicknesses ranging from 40 nm up to 2.5 ?m, by tuning the sectioning speed of the cryo-microtome. A fluorescent stereo-microscope mounted on the cryo-microtome allowed us to target the regions of interest after GFP-labeling of synapses. Thick cryo-sections were imaged by cryo-soft X-ray microscopy at a resolution better than 25 nm, while ultrathin cryo-sections of the same regions were explored in parallel at the nanometre level of resolution by cryo-electron microscopy. PMID:25301679

  16. Assembly of multiple components in a hybrid microcapsule: designing a magnetically separable Pd catalyst for selective hydrogenation.

    PubMed

    Amali, Arlin Jose; Sharma, Bikash; Rana, Rohit Kumar

    2014-09-15

    In analogy to the role of long-chain polyamines in biosilicification, poly-L-lysine facilitates the assembly of nanocomponents to design multifunctional microcapsule structures. The method is demonstrated by the fabrication of a magnetically separable catalyst that accommodates Pd nanoparticles (NPs) as active catalyst, Fe3O4 NPs as magnetic component for easy recovery of the catalyst, and silica NPs to impart stability and selectivity to the catalyst. In addition, polyamines embedded inside the microcapsule prevent the agglomeration of Pd NPs and thus result in efficient catalytic activity in hydrogenation reactions, and the hydrophilic silica surface results in selectivity in reactions depending on the polarity of substrates. PMID:25088358

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

    SciTech Connect

    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

    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.

  18. Validation Experiments supporting the CryoSat-2 mission

    NASA Astrophysics Data System (ADS)

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

    2009-12-01

    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.

  19. Structural analysis of multicellular organisms with cryo-electron tomography.

    PubMed

    Harapin, Jan; Börmel, Mandy; Sapra, K Tanuj; Brunner, Damian; Kaech, Andres; Medalia, Ohad

    2015-07-01

    We developed a method for visualizing tissues from multicellular organisms using cryo-electron tomography. Our protocol involves vitrifying samples with high-pressure freezing, thinning them with cryo-FIB-SEM (focused-ion-beam scanning electron microscopy) and applying fiducial gold markers under cryogenic conditions to the lamellae post-milling. We applied this protocol to acquire tomograms of vitrified Caenorhabditis elegans embryos and worms, which showed the intracellular organization of selected tissues at particular developmental stages in otherwise intact specimens. PMID:25961413

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

    NASA Astrophysics Data System (ADS)

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

    2014-08-01

    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 field axis via the chiral magnetic effect. The experimental observation of charge separation has previously been reported for heavy-ion collisions at the top RHIC energies. In this Letter, 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. This implies the dominance of hadronic interactions over partonic ones at lower collision energies.

  1. High gradient magnetic separation of iron oxide minerals from soil clays 

    E-print Network

    Schulze, Darrell Gene

    1977-01-01

    steel wool, placed in a strong magnetic field (1. 6 Tesla), provides the magnetic field and magnetic field gradients necessary to trap weakly magnetic, clay size particles flowing through the filter as a dilute suspension in pH 10. 5 Na C03 solution.... Of the total dithionite-citrate-bicarbonate extractable Fe 0 in 2 3 the 2-0. 2 um size fraction of six soils, 70 to 94X was recovered in the magnetic fraction which consisted of 1. 6 to 27. 7X Fe 0 by weight. For the &0. 2 pm size fraction, 11 to 40X...

  2. Study of Phase Separation in Na 2O–B 2O 3 Glass System by Nuclear Magnetic Resonance

    Microsoft Academic Search

    Wei-Fang Du; Koji Kuraoka; Tomoko Akai; Tetsuo Yazawa

    2000-01-01

    The 11B nuclear magnetic resonance (NMR) spectra, together with X-ray diffraction (XRD) and scanning electron microscopy (SEM), have been used to investigate the phase separation in 15Na2O–85B2O3 binary glass. Based on the present investigation we suggest that the phase equilibrium in sodium borate glasses is controlled by the rate competition of the nucleation and crystal growth between two immiscible phases

  3. Natural circulation loop using liquid nitrogen for cryo-detection system

    SciTech Connect

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

    2014-01-29

    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.

  4. Spin transverse separation in a two-dimensional electron-gas using an external magnetic field with a topological chirality

    NASA Astrophysics Data System (ADS)

    Tan, S. G.; Jalil, M. B. A.; Liu, Xiong-Jun; Fujita, T.

    2008-12-01

    We propose a two-dimensional electron-gas (2DEG) system in which an external magnetic field with a small chirality is applied to provide a topological spin gauge field that separates conduction electrons of opposite spins in the transverse direction. Additionally, the vertical electric field in the 2DEG, together with spin-orbit coupling, produces a SU(2) gauge field which reinforces or opposes the effect of the spin gauge. The system thus provides a tunable spin separation effect, where an applied gate voltage on the 2DEG can be used to modulate the transverse spin current. As this method leads to the enhancement or cancellation of spin separation due to the intrinsic spin-orbit coupling effect only, it may naturally distinguish the extrinsic effect from the intrinsic one.

  5. Separation of Microcystin-LR by Cyclodextrin-Functionalized Magnetic Composite of Colloidal Graphene and Porous Silica.

    PubMed

    Sinha, Arjyabaran; Jana, Nikhil R

    2015-05-13

    Microcystin-LR belongs to the family of microcystins produced by cyanobacteria and known to be the most toxic of this family. Existence of cyanobacteria in water bodies leads to the contamination of drinking water with microcystin-LR and thus their separation is essential for an advanced water purification system. Here we report functional nanocomposite-based selective separation of microcystin-LR from contaminated water. We have synthesized cyclodextrin-functionalized magnetic composite of colloidal graphene and porous silica where the cyclodextrin component offers host-guest interaction with microcystin-LR and the magnetic component offers easier separation of microcystin-LR from water. High surface area and large extent of chemical functional groups offer high loading (up to 18 wt %) of cyclodextrin with these nanocomposites, and the dispersible form of the nanocomposite offers easier accessibility of cyclodextrin to microcystin-LR. We have shown that microcystin-LR separation efficiency is significantly enhanced after functionalization with cyclodextrin, and among all the tested cyclodextrins, ?-cyclodextrin offers the best performance. We have also found that graphene-based nanocomposite offers better performance over porous silica-based nanocomposite due to better accessibility of cyclodextrins for interaction with microcystin-LR. The proposed graphene-based functional nanocomposite is environment friendly, reusable, and applicable for advanced water purification. PMID:25906257

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

    PubMed

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

    2014-01-01

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

  7. Cryo-Compressed Hydrogen Storage: Performance and Cost Review

    E-print Network

    ­ Algorithm for optimal dome shape with geodesic winding pattern (i.e., along isotensoids) ­ Algorithm for geodesic and hoop windings in cylindrical section Fatigue Analysis of Type 3 Tanks ­ Algorithm for residual Behavior: Cryo-compressed Option Total heat load is a function of initial temperature ­ 2.3 MJ for 34.3 K

  8. Microstructure-mechanical property correlation of cryo rolled Zircaloy-4

    NASA Astrophysics Data System (ADS)

    Sarkar, Apu; Murty, Korukonda L.

    2015-01-01

    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.

  9. A Bayesian View on Cryo-EM Structure Determination

    PubMed Central

    Scheres, Sjors H.W.

    2012-01-01

    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

  10. Concentration and purification by magnetic separation of the erythrocytic stages of all human Plasmodium species

    Microsoft Academic Search

    Clotilde Ribaut; Antoine Berry; Séverine Chevalley; Karine Reybier; Isabelle Morlais; Daniel Parzy; Françoise Nepveu; Françoise Benoit-Vical; Alexis Valentin

    2008-01-01

    BACKGROUND: Parasite concentration methods facilitate molecular, biochemical and immunological research on the erythrocytic stages of Plasmodium. In this paper, an adaptation of magnetic MACS® columns for the purification of human Plasmodium species is presented. This method was useful for the concentration\\/purification of either schizonts or gametocytes. RESULTS AND CONCLUSIONS: The magnetic removal of non-parasitized red blood cells (in vivo and

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

    PubMed

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

    2014-11-01

    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

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

    NASA Astrophysics Data System (ADS)

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

    2014-09-01

    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.

  13. Influence of magnetic nanoparticle size on the particle dispersion and phase separation in an ABA triblock copolymer.

    PubMed

    Wu, Jinrong; Li, Hui; Wu, Siduo; Huang, Guangsu; Xing, Wang; Tang, Maozhu; Fu, Qiang

    2014-02-27

    Oleic acid modified iron oxide nanoparticles (IONs) with different sizes were synthesized and mixed with styrene-butadiene-styrene block copolymer (SBS) with a lamellar structure. The octadecene segments on the oleic acid molecules have chemical affinity with the polybutadiene (PB) blocks, which makes IONs tend to be selectively confined in the microphase-separated PB domains. However, the dispersion state strongly depends on the ratio of the particle diameter (d) to the lamellar thickness (l) of the PB domains, which further changes the phase separation of SBS. When d/l ?0.5, most of IONs are concentrated in the middle of the PB layers at low particle loading. Upon increasing the particle loading, part of IONs contact each other to form long strings due to their strong magnetic interactions. Away from the strings, IONs are either selectively dispersed in the middle and at the interfaces of the PB domains, or randomly distributed at some regions in which the phase separation of SBS is suppressed. The phase separation of SBS transforms from the lamellar structure to a cylinder structure when the IONs loading is higher than 16.7 wt %. As d is comparable to l, IONs aggregate to form clusters of 100 to 300 nm in size, but within the clusters IONs are still selectively dispersed in the PB domains instead of forming macroscopic phase separation. It is interpreted in terms of the relatively small conformational entropy of the middle blocks of SBS; thus, incorporation of nanoparticles does not lead to much loss of conformational entropy. Although incorporation of IONs with d/l ?1 significantly increases the interfacial curvature and roughness, it has less influence on the phase separation structure of SBS due to the inhomogeneous dispersion. When d is larger than l, IONs are macroscopically separated from the SBS matrix to form clusters of hundreds of nanometers to several micrometers. More interestingly, the phase separation of SBS transforms from the lamellar structure to a two-phase co-continuous structure, probably due to the rearrangement of SBS molecules to cover the clusters with PB segments and the strong magnetic interaction exerting additional force on the SBS matrix during the evaporation of the solvent and the subsequent thermal annealing process. PMID:24479376

  14. Spinel type CoFe oxide porous nanosheets as magnetic adsorbents with fast removal ability and facile separation.

    PubMed

    Ge, X; Gu, C D; Wang, X L; Tu, J P

    2015-09-15

    Adsorption is often time consuming due to slow diffusion kinetic. Sizing he adsorbent down might help to accelerate adsorption. For CoFe spinel oxide, a magnetically separable adsorbent, the preparation of nanosheets faces many challenges including phase separation, grain growth and difficulty in preparing two-dimensional materials. In this work, we prepared porous CoFe oxide nanosheet with chemical formula of Co2.698Fe0.302O4 through topochemical transformation of a CoFe precursor, which has a layered double hydroxide (LDH) analogue structure and a large interlayer spacing. The LDH precursor was synthesized from a cheap deep eutectic solvent (DES) system. The calcined Co2.698Fe0.302O4 has small grain size (10-20nm), nanosheet morphology, and porous structure, which contribute to a large specific surface area of 79.5m(2)g(-1). The Co2.698Fe0.302O4 nanosheets show fast removal ability and good adsorption capacity for both organic waste (305mgg(-1) in 5min for Congo red) and toxic heavy metal ion (5.27mgg(-1) in 30min for Cr (VI)). Furthermore, the Co2.698Fe0.302O4 can be separated magnetically. Considering the precursor can be prepared through a fast, simple, surfactant-free and high-yield synthetic strategy, this work should have practical significance in fabricating adsorbents. PMID:26005799

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

    PubMed

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

    2014-01-15

    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

  16. Preliminary magnetic studies of lagoon and stream sediments from Chascomús Area (Argentina)—magnetic parameters as indicators of heavy metal pollution and some results of using an experimental method to separate magnetic phases

    NASA Astrophysics Data System (ADS)

    Chaparro, Marcos A. E.; Lirio, Juan M.; Nuñez, Héctor; Gogorza, Claudia S. G.; Sinito, Ana M.

    2005-11-01

    Magnetic properties of lagoon and stream sediments from Chascomús area (Buenos Aires Province) and the relevance of various magnetic parameters as giving pollution status are studied in the present work. This work is focussed on magnetic parameters, such as concentration-dependent (magnetic susceptibility, saturation anhysteric and isothermal remanent magnetisation) and feature-dependent parameters (S-ratio, coercivity of remanence, anhysteric susceptibility/magnetic susceptibility-ratio), as pollution indicators. Firstly and most importantly, different magnetic parameters and chemical measurements were correlated in order to investigate their goodness, obtaining the best results for feature-dependent magnetic parameters. Coercivity of remanence correlate very well with chemical variables, showing correlations at high level of significance up to 0.9094, and the anhysteric susceptibility/magnetic susceptibility-ratio also shows very good correlations (up to 0.8376). Some results and advantages of using a new experimental method in order to discriminate hard and soft magnetic phases are also shown. This method uses alternately backfield isothermal remanent magnetisation and alternating field demagnetisation. From the experimental separation, the presence of hard magnetic phases in some samples was confirmed.

  17. Manipulation of magnetic phase separation and orbital occupancy in manganites by strain engineering and electric field

    NASA Astrophysics Data System (ADS)

    Cui, Bin; Song, Cheng; Pan, Feng; Key Laboratory of Advanced Materials (MOE) Team

    2015-03-01

    The modification of electronic phases in correlated oxides is one of the core issues of condensed matter. We report the reversible control of ferromagnetic phase transition in manganite films by ionic liquid gating, replicating the La1-xSrxMnO3 (LSMO) phase diagram. The formation and annihilation of an insulating and magnetically hard phase in the soft magnetic matrix, which randomly nucleates and grows across the film, is directly observed under different gate voltages (VG) . The realization of reversible metal-insulator transition in colossal magnetoresistance materials can lead to the development of four-state memories. The orbital occupancy and magnetic anisotropy of LSMO films are manipulated by VG in a reversible and quantitative manner. Positive and negative VG increases and reduces the occupancy of the orbital and magnetic anisotropy that were initially favored by strain (irrespective of tensile and compressive), respectively. This finding fills in the blank of electrical manipulation of four degrees of freedom in correlated system.

  18. Problems of loss separation for crystalline and consolidated amorphous soft magnetic materials

    Microsoft Academic Search

    H. Pfutzner; P. Schonhuber; B. Erbil; G. Harasko; T. Klinger

    1991-01-01

    Losses were measured as a function of magnetization frequency fd for two advanced soft magnetic alloys: laser-scribed 0.23-mm HI-B steel ZDKH (designated HB) and consolidated amorphous Powercore (designated PC). Although domain observations on HB yielded distinct domain refinements due to the laser treatment, anomalous losses Wa still proved to be higher than the classical ones. A further refinement resulted from

  19. On a plasma sheath separating regions of oppositely directed magnetic field

    Microsoft Academic Search

    E. G. Harris

    1962-01-01

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

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

    PubMed Central

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

    2011-01-01

    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

  1. Magnetically separable Cu2O/chitosan-Fe3O4 nanocomposites: Preparation, characterization and visible-light photocatalytic performance

    NASA Astrophysics Data System (ADS)

    Cao, Chunhua; Xiao, Ling; Chen, Chunhua; Cao, Qihua

    2015-04-01

    A novel magnetically-separable visible-light-induced photocatalyst, Cu2O/chitosan-Fe3O4 nanocomposite (Cu2O/CS-Fe3O4 NC), was prepared via a facile one-step precipitation-reduction process by using magnetic chitosan chelating copper ions as precursor. The structure and properties of Cu2O/CS-Fe3O4 NCs were characterized by XRD, FT-IR, SEM, HRTEM, SAED, EDS, BET, VSM, XPS and UV-vis/DRS. The photocatalytic activity of Cu2O/CS-Fe3O4 NCs was evaluated by decolorization of reactive brilliant red X-3B (X-3B) under visible light irradiation. The characterization results indicated that Cu2O/CS-Fe3O4 NCs exhibited relatively large specific surface areas and special dimodal pore structure because Cu2O was wrapped in chitosan matrix embedded with Fe3O4 nanoparticles. The tight combination of magnetic Fe3O4 and semiconductor Cu2O through chitosan made the nanocomposites show good superparamagnetism and photocatalytic activity. It was found that X-3B could be decolorized more efficiently in acidic media than in neutral or alkaline media. The decolorization of X-3B was ascribed to the synergistic effect of photocatalysis and adsorption. Cu2O/CS-Fe3O4 NCs could be easily separated from the solution by an external magnet, and the decolorization rates of X-3B were still above 87% after five reaction cycles, indicating that Cu2O/CS-Fe3O4 NCs had excellent reusability and stability.

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

    Microsoft Academic Search

    Jinxin Li; Jinjun Zhang; Haijun Yang; Yongcheng Ning

    2006-01-01

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

  3. Cryo-Electron Microscopy of Viruses Infecting Bacterium

    NASA Astrophysics Data System (ADS)

    Chiu, Wah

    2010-03-01

    Single particle cryo-EM can yield structures of infectious bacterial viruses with and without imposed icosahedral symmetry at subnanometer resolution. Reconstructions of infectious and empty phage particles show substantial differences in the portal vertex protein complex at one of the 12 pentameric vertices in the icosahedral virus particle through which the viral genomes are packaged or released. In addition, electron cryo-tomography of viruses during infecting its bacterial host cell displayed multiple conformations of the tail fiber of the virus. Our structural observations by single particle and tomographic reconstructions suggest a mechanism whereby the viral tail fibers, upon binding to the host cell, induce a cascade of structural alterations of the portal vertex protein complex that triggers DNA release.

  4. PHYSICAL REVIEW B 84, 024417 (2011) Coercivity enhancement driven by interfacial magnetic phase separation in

    E-print Network

    Pennycook, Steve

    2011-01-01

    . Leighton1,* 1 Department of Chemical Engineering and Materials Science, University of Minnesota-separated layer, leading us to advance an explanation for the coercivity enhancement in terms of the pinning to STO, lead to exceptionally high tunneling magnetoresistance (TMR) at cryogenic temperatures.2

  5. Covariance Matrix Estimation for the Cryo-EM Heterogeneity Problem*

    PubMed Central

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

    2015-01-01

    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. PMID:25699132

  6. NASA IN-STEP Cryo System Experiment flight test

    Microsoft Academic Search

    S. C. Russo; R. S. Sugimura

    1996-01-01

    The Cryo System Experiment (CSE), a NASA In-Space Technology Experiments Program (IN-STEP) flight experiment, was flown on Space Shuttle Discovery (STS 63) in February 1995. The experiment was developed by Hughes Aircraft Company to validate in zero-g space a 65 K cryogenic system for focal planes, optics, instruments or other equipment (gamma-ray spectrometers and infrared and submillimetre imaging instruments) that

  7. Cryo-balloon catheter position planning using AFiT

    NASA Astrophysics Data System (ADS)

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

    2012-02-01

    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.

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

    NASA Technical Reports Server (NTRS)

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

    1975-01-01

    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.

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

    E-print Network

    Boyer, Edmond

    .Kuzhir1 , G.Bossis1 , A.Meunier1 , L.Suloeva2 and A.Zubarev3 1 University of Nice Sophia Antipolis-sized particles is subjected to a homogeneous magnetic field, the nanoparticles are attracted)]. In this paper, we present detailed experimental and theoretical studies of nanoparticle concentration profiles

  10. Low-cost cryo-light microscopy stage fabrication for correlated light/electron microscopy.

    PubMed

    Carlson, David B; Evans, James E

    2011-01-01

    The coupling of cryo-light microscopy (cryo-LM) and cryo-electron microscopy (cryo-EM) poses a number of advantages for understanding cellular dynamics and ultrastructure. First, cells can be imaged in a near native environment for both techniques. Second, due to the vitrification process, samples are preserved by rapid physical immobilization rather than slow chemical fixation. Third, imaging the same sample with both cryo-LM and cryo-EM provides correlation of data from a single cell, rather than a comparison of "representative samples". While these benefits are well known from prior studies, the widespread use of correlative cryo-LM and cryo-EM remains limited due to the expense and complexity of buying or building a suitable cryogenic light microscopy stage. Here we demonstrate the assembly, and use of an inexpensive cryogenic stage that can be fabricated in any lab for less than $40 with parts found at local hardware and grocery stores. This cryo-LM stage is designed for use with reflected light microscopes that are fitted with long working distance air objectives. For correlative cryo-LM and cryo-EM studies, we adapt the use of carbon coated standard 3-mm cryo-EM grids as specimen supports. After adsorbing the sample to the grid, previously established protocols for vitrifying the sample and transferring/handling the grid are followed to permit multi-technique imaging. As a result, this setup allows any laboratory with a reflected light microscope to have access to direct correlative imaging of frozen hydrated samples. PMID:21673645

  11. Nanostructuring of Undoped ZnSb by Cryo-Milling

    NASA Astrophysics Data System (ADS)

    Song, X.; Valset, K.; Graff, J. S.; Thøgersen, A.; Gunnæs, A. E.; Luxsacumar, S.; Løvvik, O. M.; Snyder, G. J.; Finstad, T. G.

    2015-03-01

    We report the preparation of nanosized ZnSb powder by cryo-milling. The effect of cryo-milling then hot-pressing of undoped ZnSb was investigated and compared with that of room temperature ball-milling and hot-pressing under different temperature conditions. ZnSb is a semiconductor with favorable thermoelectric properties when doped. We used undoped ZnSb to study the effect of nanostructuring on lattice thermal conductivity, and with little contribution at room temperature from electronic thermal conductivity. Grain growth was observed to occur during hot-pressing, as observed by transmission electron microscopy and x-ray diffraction. The thermal conductivity was lower for cryo-milled samples than for room-temperature ball-milled samples. The thermal conductivity also depended on hot-pressing conditions. The thermal conductivity could be varied by a factor of two by adjusting the process conditions and could be less than a third that of single-crystal ZnSb.

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

    PubMed

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

    2014-09-15

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

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

    PubMed

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

    2014-06-25

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

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

    Microsoft Academic Search

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

    1992-01-01

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

  15. Arc-wall interaction phenomena immediately after contact separation in magnet-blast interrupters

    Microsoft Academic Search

    E. Gauster; W. Rieder

    1995-01-01

    Arc-wall interaction phenomena without and with a baffle plate arranged next the switching contacts opposite to the direction of arc motion were investigated in a model interrupter. The criterion considered was the time of reduced arc motion immediately after contact separation. Arc current geometry of contacts and walls, contact material (Cu, Ag\\/C, Ag\\/SnO2, Ag\\/CdO) and the materials of lateral walls

  16. Arc-wall interaction phenomena immediately after contact separation in magnet-blast interrupters

    Microsoft Academic Search

    E. Gauster; W. F. Rieder

    1996-01-01

    Arc-wall interaction phenomena, with and without a baffle plate arranged next the switching contacts opposite to the direction of arc motion, were investigated in a model interrupter. The criterion considered was the time of reduced arc motion immediately after contact separation. Arc current, geometry of contacts and walls, contact materials (Cu, Ag\\/C, Ag\\/SnO2, Ag\\/CdO) and the materials of lateral walls

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

    SciTech Connect

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

    2011-11-15

    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.

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

    SciTech Connect

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

    2013-06-10

    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.

  19. Application of magnetite hexacyanoferrate composites in magnetically assisted chemical separation of cesium

    Microsoft Academic Search

    R. D. Ambashta; D. S. Deshingkar; P. K. Wattal; D. Bahadur

    2006-01-01

    Summary  Potassium nickel hexacyanoferrate composite with magnetite finds application in the recovery of cesium from low-level liquid\\u000a waste using magnetic assistance. The apparent sorption capability of hexacyanoferrate-magnetite composite and potassium nickel(II)\\u000a hexacyanoferrate(II) matched indicating no loss in sorption capability as a consequence of coating to nanoscale magnetite\\u000a substrate. Selectivity for cesium in a broad pH range, selectivity in the presence of

  20. PDMAEMA-grafted core-shell-corona particles for nonviral gene delivery and magnetic cell separation.

    PubMed

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

    2013-09-01

    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

  1. CryoSat-2: A new perspective on the Cryosphere

    NASA Astrophysics Data System (ADS)

    Shepherd, A.; Armitage, T.; Briggs, K.; Flament, T.; Hogg, A. E.; McMillan, M.; Muir, A.; Ridout, A.; Sundal, A.; Tilling, R.; Wingham, D.

    2014-12-01

    CryoSat-2 is ESA's first satellite mission dedicated to measuring changes in the polar land ice and sea ice cover. Following its launch in April 2010, we have examined the performance of the instrument over the continental ice sheets of Antarctica and Greenland, the Artic Ocean, and, for the purposes of calibration, over the oceans. We have confirmed the engineering performance at system level of the interferometer demonstrating that it measures across-track surface slopes with a precision of 25 micro-radians and an accuracy of 10 micro-radians, greatly exceeding the pre-launch specifications (100 micro-radians). Over the polar ice sheets, we have examined the performance of the range estimation, and determined the range precision to be 19 cm RMS at 20 Hz. We have examined the retrieval of the phase information over the ice sheets, and found the phase estimates to be robust and little affected by the uncertain ice sheet topography. Based on the calibration of the interferometer, the contribution of the across track slope error is, at 0.4 mm, negligible. Over marine sea ice, we have verified the discrimination of sea ice and ocean lead returns using contemporaneous SAR imagery from ENVISAT, and we have estimated the precision of individual (20 Hz) measurements to be 2 cm. In summary, with the corrected data products, we are able to confirm that the system performance of CryoSat-2 will meet or exceed its specification over the continental and marine ice sheets. This presenetation sumamrises the key outcomes of the mission performance, and presents a series of example case studies where CryoSat-2 data have been applied to study changes in Earth's land and sea ice cover. We show that in 4 years CryoSat has been able to detect changes in the mass of the Antarctic and Greenland ice sheets with an accuracy comparable to that of the past 20 years of conventional satellite altimetry and that important changes have occured in these regions, we show that CryoSat has been able to quantify changes in the volume of sea ice across the entire northern hemisphere for the first time and that unexpected changes have occurred, and we show that the mission has been able to detect changes in the volume of rugged, glaciated terrain, that were beyond the capability of past altiemter missions and that are in places extreme in comparison to past observations.

  2. ? SR study of real space magnetic phase separation in Mn3O4

    NASA Astrophysics Data System (ADS)

    Zakjevskii, Alexander; Thaler, Alexander; Reig-I-Plessis, Dalmau; Brodsky, Isaac; Gim, Yewon; Aczel, Adam; Cooper, S. Lance; MacDougall, Gregory

    2015-03-01

    The material Mn3O4 is a magnetically frustrated spinel which exhibits three distinct magnetic transitions below 42 K. Recent work has shown that the lowest of these is accompanied by an orthorhombic structural distortion, implying strong magneto-elastic coupling. Magnetic force microscopy (MFM) measurements indicate a substantial region of phase coexistence below this transition, with domain walls that order on the mesoscale. It is further suggested that a tradeoff in ordered volume with field may play a role in the recent quantum phase transition reported in this material. To follow up on these ideas, we have performed a series of zero- and transverse-field muon spin rotation measurements on single-crystal Mn3O4. The zero-field data clearly show the co-existence of ordered and disorder volumes, consistent with MFM results. Here we report these data, and further attempts to vary the ordered volume with applied field. We will discuss both zero- and transverse-field results within the context of the current understanding of the material. This material is based upon work supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Award Number DE-FG02-07ER46453.

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

    PubMed

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

    2013-06-15

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

  4. Rapid removal and separation of iron(II) and manganese(II) from micropolluted water using magnetic graphene oxide.

    PubMed

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

    2014-06-25

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

  5. Hour-glass magnetic excitations induced by nanoscopic phase separation in cobalt oxides La$_{2-x}$Sr$_x$CoO$_4$

    E-print Network

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

    2015-01-01

    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 superconduc...

  6. Efficient estimation of three-dimensional covariance and its application in the analysis of heterogeneous samples in cryo-electron microscopy.

    PubMed

    Liao, Hstau Y; Hashem, Yaser; Frank, Joachim

    2015-06-01

    Single-particle cryogenic electron microscopy (cryo-EM) is a powerful tool for the study of macromolecular structures at high resolution. Classification allows multiple structural states to be extracted and reconstructed from the same sample. One classification approach is via the covariance matrix, which captures the correlation between every pair of voxels. Earlier approaches employ computing-intensive resampling and estimate only the eigenvectors of the matrix, which are then used in a separate fast classification step. We propose an iterative scheme to explicitly estimate the covariance matrix in its entirety. In our approach, the flexibility in choosing the solution domain allows us to examine a part of the molecule in greater detail. Three-dimensional covariance maps obtained in this way from experimental data (cryo-EM images of the eukaryotic pre-initiation complex) prove to be in excellent agreement with conclusions derived by using traditional approaches, revealing in addition the interdependencies of ligand bindings and structural changes. PMID:25982529

  7. Phase-separated alloys for bulk exchange-biased permanent magnets

    NASA Astrophysics Data System (ADS)

    Lewis, L. H.; Harland, C. L.; McCallum, R. W.; Kramer, M. J.; Dennis, K. W.

    2006-04-01

    Explorations in the metallurgical synthesis from the melt of bulk permanent magnets with coercivity conferred by the exchange bias mechanism were carried out in a two-phase materials system composed of ferromagnetic FeCo and antiferromagnetic, nominally equiatomic AuMn. Rapid solidification synthesis of composite alloys of nominal composition (Fe65Co35)100-x(AuMn)x (x=5, 10, and 15) was carried out. The ribbons possess AuMn and Au2Mn spherical phases in a bcc (Fe,Co) matrix with a bimodal size distribution of nanoscaled and micron sizes. Magnetization measurements of the composite confirm an exchange bias effect correlated with a coercivity increase over that of the (Fe,Co) melt-spun base alloy. While the exchange bias effect is small, the enhanced coercivity and shifted hysteresis loop observed in a single sample create a strong argument for coercivity enhancement conferred by the exchange bias interaction between antiferromagnetic and ferromagnetic phases in a bulk melt-spun nanocomposite material.

  8. Versatile fabrication of ultralight magnetic foams and application for oil-water separation.

    PubMed

    Chen, Ning; Pan, Qinmin

    2013-08-27

    Ultralow-density (<10 mg cm(-3)) materials have many important technological applications; however, most of them were fabricated using either expensive materials or complicated procedures. In this study, ultralight magnetic Fe2O3/C, Co/C, and Ni/C foams (with a density <5 mg cm(-3)) were fabricated on the centimeter scale by pyrolyzing commercial polyurethane sponge grafted with polyelectrolyte layers based on the corresponding metal acrylate at 400 °C. The ultralight foams consisted of 3D interconnected hollow tubes that have a diameter of micrometer and nanoscale wall thickness, forming hierarchical structures from macroscopic to nanometer length scales. More interesting was that the wall thickness and morphology of the microtubes could be tuned by controlling the concentrations of acrylic acid and metallic cations. After modification with low-surface-energy polysiloxane, the ultralight foams showed superhydrophobicity and superoleophilicity, which quickly and selectively absorbed a variety of oils from a polluted water surface under magnetic field. The oil absorption capacity reached 100 times of the foams' own weight, exhibiting one of the highest values among existing absorptive counterparts. By controlling the composition and conformation of the grafted polyelectrolyte layers, the present approach is extendable to fabricate a variety of ultralow-density materials desirable for absorptive materials, electrode materials, catalyst supports, etc. PMID:23875978

  9. Phase-separated alloys for bulk exchange-biased permanent magnets

    SciTech Connect

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

    2006-04-15

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

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

    SciTech Connect

    Yashita, S.

    1983-01-01

    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.

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

    NASA Technical Reports Server (NTRS)

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

    2013-01-01

    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.

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

    SciTech Connect

    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

    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.

  13. A magnetically separable biocatalyst for resolution of racemic naproxen methyl ester.

    PubMed

    Ozyilmaz, Elif; Sayin, Serkan

    2013-11-01

    Candida rugosa lipase (CRL) was encapsulated via the sol-gel method, using 5, 11, 17, 23-tetra-tert-butyl-25,27-bis(2-aminopyridine)carbonylmethoxy-26, 28-dihydroxy-calix[4]arene-grafted magnetic Fe3O4 nanoparticles (Calix-M-E). The catalytic activity of encapsulated lipase (Calix-M-E) was tested both in the hydrolysis of p-nitrophenyl palmitate (p-NPP) and the enantioselective hydrolysis of racemic naproxen methyl ester. The present study demonstrated that the calixarene-based compound has the potential to enhance both reaction rate and enantioselectivity of the lipase-catalyzed hydrolysis of racemic naproxen methyl ester. The encapsulated lipase (Calix-M-E) had great catalytic activity and enantioselectivity (E > 400), as well as remarkable reusability as compared to the encapsulated lipase without supports (E = 137) for S-Naproxen. PMID:23525833

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

    SciTech Connect

    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

    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.

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

    NASA Technical Reports Server (NTRS)

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

    2011-01-01

    Chromospheric fibrils are generally thought to trace out low-lying, mainly horizontal magnetic elds that fan out from flux concentrations in the photosphere. A high-resolution (approximately 0.1" per pixel) image, taken in the core of the Ca II 854.2 nm line and covering an unusually large area, shows the dark brils within an active region remnant as fine, looplike features that are aligned parallel to each other and have lengths comparable to a supergranular diameter. Comparison with simultaneous line-of-sight magnetograms confirms that the fibrils are centered above intranetwork areas (supergranular cell interiors), with one end rooted just inside the neighboring plage or strong unipolar network but the other endpoint less clearly defined. Focusing on a particular arcade-like structure lying entirely on one side of a lament channel (large-scale polarity inversion), we find that the total amount of positive-polarity flux underlying this "fibril arcade" is approximately 50 times greater than the total amount of negative-polarity flux. Thus, if the brils represent closed loops, they must consist of very weak fields (in terms of total magnetic flux), which are interpenetrated by a more vertical field that contains most of the flux. This surprising result suggests that the fibrils in unipolar regions connect the network to the nearby intranetwork flux, while the bulk of the network flux links to remote regions of the opposite polarity, forming a second, higher canopy above the fibril canopy. The chromospheric field near the edge of the network thus has an interlaced structure resembling that in sunspot penumbrae.

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

    PubMed Central

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

    2013-01-01

    We have visualized by cryo-electron microscopy (cryo-EM) the complex of the anthrax protective antigen (PA) translocon and the N-terminal domain of anthrax lethal factor (LFN) inserted into a nanodisc model lipid bilayer. We have determined the structure of this complex at a nominal resolution of 16 Å by single-particle analysis and three-dimensional reconstruction. Consistent with our previous analysis of negatively stained unliganded PA, the translocon comprises a globular structure (cap) separated from the nanodisc bilayer by a narrow stalk that terminates in a transmembrane channel (incompletely distinguished in this reconstruction). The globular cap is larger than the unliganded PA pore, probably due to distortions introduced in the previous negatively stained structures. The cap exhibits larger, more distinct radial protrusions, previously identified with PA domain three, fitted by elements of the NMFF PA prepore crystal structure. The presence of LFN, though not distinguished due to the seven-fold averaging used in the reconstruction, contributes to the distinct protrusions on the cap rim volume distal to the membrane. Furthermore, the lumen of the cap region is less resolved than the unliganded negatively stained PA, due to the low contrast obtained in our images of this specimen. Presence of the LFN extended helix and N terminal unstructured regions may also contribute to this additional internal density within the interior of the cap. Initial NMFF fitting of the cryoEM-defined PA pore cap region positions the Phe clamp region of the PA pore translocon directly above an internal vestibule, consistent with its role in toxin translocation. PMID:23494942

  17. 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...

  18. Symposium on Cryo-electron Microscopy of Biological Specimens McMaster University. Hamilton. ON

    E-print Network

    Hitchcock, Adam P.

    . McMaster University Cryo-EM structure of the 30S ribosomal subunit bound to the assembly factor Yje resolution: better images and better image alignment for single particle cryo-EM of small, asymmetric protein. USA The molecular mechanism of protein synthesis in eukaryotes 2:10-2:40 pm Cesar Khursigara

  19. CryoSat data quality assessment and product evolutions

    NASA Astrophysics Data System (ADS)

    Bouffard, Jerome; Femenias, Pierre; Parrinello, Tommaso; Fornari, Marco; Brockley, David; Scagliola, Michele; Calafat, Francisco; Roca, Monica

    2015-04-01

    The main payload of the ESA Earth Explorer CryoSat satellite is a Ku band pulse-width limited radar altimeter, operating in 3 different modes function of a mask of geographical zones. Over the ocean and ice sheet interiors, CryoSat mainly operates like a conventional pulse-limited radar altimeter whereas over sea ice, coherently transmitted echoes are combined in order to carry out measurements at a higher resolution. Around ice sheet margins, a 2nd antenna is used as an interferometer in order to determine the across-track angle to the earliest radar returns. Two kinds of data are distributed to the scientific user community and are quality controlled and validated by ESA/ESRIN SPPA office with the support of an industrial consortium: the Level 1b products essentially contain average echoes collected along the ground track while the Level 2 products contain elevations and associated geophysical parameters retrieved from these echoes. In this poster we first briefly present the characteristics of Level 1b and Level 2 CryoSat products over ocean, land ice and sea ice in addition to the results of recent quality control activities. Due to anomalies detected in previous data release and the need of continuously improving the data quality, ESA and its industrial partners has implemented a new version of the processors by the early of 2015, followed by a full reprocessing campaign. The main evolutions of this so called "Baseline C", the validation of the associated Test Data Set and the main improvements expected from this new release are also presented.

  20. Cryo-electron tomography of microtubule-kinesin motor complexes.

    PubMed

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

    2010-05-01

    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 presents a serious limitation and confines 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 sub-volumes 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

  1. Semi-continuous in situ magnetic separation for enhanced extracellular protease production-modeling and experimental validation.

    PubMed

    Cerff, Martin; Scholz, Alexander; Käppler, Tobias; Ottow, Kim E; Hobley, Tim J; Posten, Clemens

    2013-08-01

    In modern biotechnology proteases play a major role as detergent ingredients. Especially the production of extracellular protease by Bacillus species facilitates downstream processing because the protease can be directly harvested from the biosuspension. In situ magnetic separation (ISMS) constitutes an excellent adsorptive method for efficient extracellular protease removal during cultivation. In this work, the impact of semi-continuous ISMS on the overall protease yield has been investigated. Results reveal significant removal of the protease from Bacillus licheniformis cultivations. Bacitracin-functionalized magnetic particles were successfully applied, regenerated and reused up to 30 times. Immediate reproduction of the protease after ISMS proved the biocompatibility of this integrated approach. Six subsequent ISMS steps significantly increased the overall protease yield up to 98% because proteolytic degradation and potential inhibition of the protease in the medium could be minimized. Furthermore, integration of semi-continuous ISMS increased the overall process efficiency due to reduction of the medium consumption. Process simulation revealed a deeper insight into protease production, and was used to optimize ISMS steps to obtain the maximum overall protease yield. PMID:23475553

  2. Spatiotemporally separating electron and phonon thermal transport in L1{sub 0} FePt films for heat assisted magnetic recording

    SciTech Connect

    Xu, D. B., E-mail: dongbin.xu@seagate.com [Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois 60439 (United States); Department of Materials Science and Engineering, National University of Singapore, 117576 Singapore (Singapore); Sun, C. J., E-mail: cjsun@aps.anl.gov, E-mail: msecgm@nus.edu.sg; Ho, P.; Chen, J. S.; Chow, G. M., E-mail: cjsun@aps.anl.gov, E-mail: msecgm@nus.edu.sg [Department of Materials Science and Engineering, National University of Singapore, 117576 Singapore (Singapore); Brewe, D. L.; Heald, S. M.; Zhang, X. Y. [Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois 60439 (United States); Han, S.-W. [Department of Physics Education and Institute of Fusion Science, Chonbuk National University, Jeonju 561-756 (Korea, Republic of)

    2014-06-28

    We report the spatio-temporal separation of electron and phonon thermal transports in nanostructured magnetic L1{sub 0} FePt films at the nanometer length scale and the time domain of tens of picosecond, when heated with a pulsed laser. We demonstrate that lattice dynamics measured using the picosecond time-resolved laser pump/X-ray probe method on the FePt (002) and Ag (002) Bragg reflections from different layers provided the information of nanoscale thermal transport between the layers. We also describe how the electron and phonon thermal transports in nanostructured magnetic thin films were separated.

  3. Direct observation of magnetic domains in phase separated Nd0.7Ca0.3MnO3 single crystals

    Microsoft Academic Search

    Xiao-Juan Fan; Hideomi Koinuma; Tetsuya Hasegawa

    2002-01-01

    The magnetic properties of single-crystalline Nd0.7Ca0.3MnO3 were studied with both macroscopic and microscopic probes. The magnetization shows large irreversibility behavior between zero-field-cooled and field-cooled data at low field, suggesting a phase separation driven by competition between ferromagnetic and antiferromagnetic phases. The scanning superconducting quantum interference device microscope observations under zero field gave clear evidence that the compound includes ferromagnetic regions

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

    NASA Technical Reports Server (NTRS)

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

    2012-01-01

    Chromospheric fibrils are generally thought to trace out horizontal magnetic fields that fan out from flux concentrations in the photosphere. A high-resolution (0.2") image taken in the core of the Ca IJ854.2 nm line shows the dark fibrils within an active region remnant as fine, loop-like features that are aligned parallel to each other and have lengths on the order of a supergranular diameter (approx.30 Mm). Comparison with a line-of-sight magnetogram confirms that the fibrils are centered above intranetwork areas, with one end rooted just inside the neighboring plage or strong unipolar network but the other endpoint less clearly defined. Focusing on a particular arcade-like structure lying entirely on one side of a filament channel (large-scale polarity inversion), we find that the total amount of positive-polarity flux underlying this "fibril arcade' is 50 times greater than the total amount of negative-polarity flux. Thus, if the fibrils represent closed loops, they must consist of very weak fields (in terms of flux density), which are interpenetrated by a more vertical field that contains most of the flux. This surprising result suggests that the fibrils in unipolar regions connect the network to the nearby intranetwork flux, while the bulk of the network flux is diverted upward into the corona and connects to remote regions of the opposite polarity. We conclude that the chromospheric field near the edge of the network has an interlaced structure resembling that in sunspot penumbrae, with the fibrils representing the low-lying horizontal flux that remains trapped within the highly nonpotential chromospheric layer.

  5. Assessment of Lead Discrimination from CryoSat-2

    NASA Astrophysics Data System (ADS)

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

    2012-12-01

    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.

  6. Validation of CryoSat-2 derived lake levels

    NASA Astrophysics Data System (ADS)

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

    2015-04-01

    The SIRAL altimeter on-board the ESA satellite CryoSat-2 is the first radar altimeter that is capable of operating in synthetic aperture radar (SAR) mode. The SAR technology provides a much higher along-track resolution compared to conventional altimetry. The higher resolution makes it possible to accurately monitor much smaller water bodies than previously. In this study, which is part of the FP7 project Land and Ocean take up from Sentinel-3 (LOTUS), we examine and validate Cryosat-2 derived lake levels and as a reference we compare our results with lake levels based on Envisat data. As a test case we consider 5 lakes; Vänern (Sweden), Okeechobee (Florida, US), Arresø, Mossø, and Skanderborgsø (Denmark), which are ranging from approximately 9 km2 to 5655 km2. We estimate the along-track precision and the accuracy by validating the estimated lake levels with gauge data from Okeechobee and Vänern. We find that the precision based on CryoSat-2 increase significantly for small lakes compared to Envisat. Despite the spatially varying lake crossings, Cryosat-2 is able to provide lake level time series of a quality that is comparable to or better than Envisat. Hence, these results demonstrate the promising possibilities of the upcoming mission Sentinel-3, which potentially will be able to provide accurate time series for small lakes.

  7. 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 ...

  8. 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

    Kasagi, Nobuhide

    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

  9. Skeletal muscle triad junction ultrastructure by Focused-Ion-Beam milling of muscle and Cryo-Electron Tomography

    PubMed Central

    Wagenknecht, Terence; Hsieh, Chyongere; Marko, Michael

    2015-01-01

    Cryo-electron tomography (cryo-ET) has emerged as perhaps the only practical technique for revealing nanometer-level three-dimensional structural details of subcellular macromolecular complexes in their native context, inside the cell. As currently practiced, the specimen should be 0.1- 0.2 microns in thickness to achieve optimal resolution. Thus, application of cryo-ET to intact frozen (vitreous) tissues, such as skeletal muscle, requires that they be sectioned. Cryo-ultramicrotomy is notoriously difficult and artifact-prone when applied to frozen cells and tissue, but a new technique, focused ion beam milling (cryo-FIB), shows great promise for “thinning” frozen biological specimens. Here we describe our initial results in applying cryo-FIB and cryo-ET to triad junctions of skeletal muscle.

  10. Low cost, high performance processing of single particle cryo-electron microscopy data in the cloud.

    PubMed

    Cianfrocco, Michael A; Leschziner, Andres E

    2015-01-01

    The advent of a new generation of electron microscopes and direct electron detectors has realized the potential of single particle cryo-electron microscopy (cryo-EM) as a technique to generate high-resolution structures. Calculating these structures requires high performance computing clusters, a resource that may be limiting to many likely cryo-EM users. To address this limitation and facilitate the spread of cryo-EM, we developed a publicly available 'off-the-shelf' computing environment on Amazon's elastic cloud computing infrastructure. This environment provides users with single particle cryo-EM software packages and the ability to create computing clusters with 16-480+ CPUs. We tested our computing environment using a publicly available 80S yeast ribosome dataset and estimate that laboratories could determine high-resolution cryo-EM structures for $50 to $1500 per structure within a timeframe comparable to local clusters. Our analysis shows that Amazon's cloud computing environment may offer a viable computing environment for cryo-EM. PMID:25955969

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

    PubMed

    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

    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

  12. Usefulness of two-point Dixon fat-water separation technique in gadoxetic acid-enhanced liver magnetic resonance imaging

    PubMed Central

    Ding, Ying; Rao, Sheng-Xiang; Chen, Cai-Zhong; Li, Ren-Chen; Zeng, Meng-Su

    2015-01-01

    AIM: To compare differences between volumetric interpolated breath-hold examination (VIBE) using two-point Dixon fat-water separation (Dixon-VIBE) and chemically selective fat saturation (FS-VIBE) with magnetic resonance imaging examination. METHODS: Forty-nine patients were included, who were scanned with two VIBE sequences (Dixon-VIBE and FS-VIBE) in hepatobiliary phase after gadoxetic acid administration. Subjective evaluations including sharpness of tumor, sharpness of vessels, strength and homogeneity of fat suppression, and artifacts that were scored using a 4-point scale. The liver-to-lesion contrast was also calculated and compared. RESULTS: Dixon-VIBE with water reconstruction had significantly higher subjective scores than FS-VIBE in strength and homogeneity of fat suppression (< 0.0001) but lower scores in sharpness of tumor (P < 0.0001), sharpness of vessels (P = 0.0001), and artifacts (P = 0.034). The liver-to-lesion contrast on Dixon-VIBE images was significantly lower than that on FS-VIBE (16.6% ± 9.4% vs 23.9% ± 12.1%, P = 0.0001). CONCLUSION: Dixon-VIBE provides stronger and more homogenous fat suppression than FS-VIBE, while has lower clarity of focal liver lesions in hepatobiliary phase after gadoxetic acid administration. PMID:25945017

  13. Magnetically Separable Fe3O4/AgBr Hybrid Materials: Highly Efficient Photocatalytic Activity and Good Stability

    NASA Astrophysics Data System (ADS)

    Cao, Yuhui; Li, Chen; Li, Junli; Li, Qiuye; Yang, Jianjun

    2015-06-01

    Magnetically separable Fe3O4/AgBr hybrid materials with highly efficient photocatalytic activity were prepared by the precipitation method. All of them exhibited much higher photocatalytic activity than the pure AgBr in photodegradation of methyl orange (MO) under visible light irradiation. When the loading amount of Fe3O4 was 0.5 %, the hybrid materials displayed the highest photocatalytic activity, and the degradation yield of MO reached 85 % within 12 min. Silver halide often suffers serious photo-corrosion, while the stability of the Fe3O4/AgBr hybrid materials improved apparently than the pure AgBr. Furthermore, depositing Fe3O4 onto the surface of AgBr could facilitate the electron transfer and thereby leading to the elevated photocatalytic activity. The morphology, phase structure, and optical properties of the composites were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), UV-visible diffuse reflectance spectra (UV-vis DRS), and photoluminescence (PL) techniques.

  14. Magnetically Separable Fe3O 4/AgBr Hybrid Materials: Highly Efficient Photocatalytic Activity and Good Stability.

    PubMed

    Cao, Yuhui; Li, Chen; Li, Junli; Li, Qiuye; Yang, Jianjun

    2015-12-01

    Magnetically separable Fe3O4/AgBr hybrid materials with highly efficient photocatalytic activity were prepared by the precipitation method. All of them exhibited much higher photocatalytic activity than the pure AgBr in photodegradation of methyl orange (MO) under visible light irradiation. When the loading amount of Fe3O4 was 0.5 %, the hybrid materials displayed the highest photocatalytic activity, and the degradation yield of MO reached 85 % within 12 min. Silver halide often suffers serious photo-corrosion, while the stability of the Fe3O4/AgBr hybrid materials improved apparently than the pure AgBr. Furthermore, depositing Fe3O4 onto the surface of AgBr could facilitate the electron transfer and thereby leading to the elevated photocatalytic activity. The morphology, phase structure, and optical properties of the composites were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), UV-visible diffuse reflectance spectra (UV-vis DRS), and photoluminescence (PL) techniques. PMID:26058513

  15. Preparation of anionic polyelectrolyte modified magnetic nanoparticles for rapid and efficient separation of lysozyme from egg white.

    PubMed

    Chen, Jia; Lin, Yuexin; Jia, Li

    2015-04-01

    Poly(sodium 4-styrenesulfonate) modified magnetic nanoparticles (PSS-MNPs) were successfully synthesized and characterized by transmission electron microscopy, scanning electron microscopy, zeta potential, vibrating sample magnetometry, and Fourier-transform infrared spectrometry. The PSS-MNPs were found to enable effective separation of lysozyme from egg white. The impacts of solution pH, ionic strength, and contact time on the adsorption process were investigated. The adsorption kinetic data were well fitted using a pseudo-second-order kinetic model and the adsorption equilibrium can be reached in 3 min. The adsorption isotherm data could be well described by the Langmuir equation. The maximum adsorption capacity of PSS-MNPs for lysozyme was calculated to be 476.2 mg g(-1) according to the Langmuir adsorption isotherm. The fast and efficient adsorption of lysozyme by PSS-MNPs was mainly based on electrostatic interactions between them. The adsorbed lysozyme can be eluted using 20mM phosphate buffer (pH 7.0) containing 1.0M NaCl with a recovery of 96%. The extracted lysozyme from egg white demonstrated high purity, retaining about 90.7% of total lysozyme activity. PMID:25728660

  16. CryoSat: ESA's Ice Explorer Mission: status and achievements

    NASA Astrophysics Data System (ADS)

    Parrinello, Tommaso; Mardle, Nicola; Hoyos Ortega, Berta; Bouzinac, Catherine; Badessi, Stefano; Frommknecht, Bjorn; Davidson, Malcolm; Fornari, Marco; Cullen, Robert

    2013-04-01

    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. Experimental evidence have shown that data is of high quality thanks to an altimeter that is behaving exceptional well within its design specifications. In April 2012, the first winter [2010 -2011] sea-ice variation map of the Arctic was released to the scientific community. 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 accessing Cryosat products following the new ESA Earth Observation Data Policy.

  17. Electron microscopy of flatworms standard and cryo-preparation methods.

    PubMed

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

    2010-01-01

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

  18. Pressure-induced tuning of a magnetic phase separation in Nd0.53Sr0.47MnO3

    SciTech Connect

    Baldini, Maria [Advanced Photon Source, Argonne National Laboratory; Ding, Yang [Advanced Photon Source, Argonne National Laboratory; Wang, Shibing [Stanford University; Lin, Yu [Stanford University; Tulk, Christopher A [ORNL; Moreira Dos Santos, Antonio F [ORNL; Mitchell, John F. [Argonne National Laboratory (ANL); Haskel, D. [Argonne National Laboratory (ANL); Mao, Wendy [Stanford University

    2012-01-01

    X-ray magnetic circular dichroism and neutron diffraction measurements were conducted in situ at high pressure and low temperature to investigate the evolution of the magnetic properties of Nd0.53Sr0.47MnO3 (NSMO47). The neutron diffraction data provide the experimental evidence for the presence of antiferromagnetic domains within the conducting ferromagnetic host at ambient pressure. The antiferromagnetic phase becomes dominant above 3 GPa with a concomitant reduction of the FM phase. Those findings indicate that the magnetic ground state of NSMO47 is more complex than previously reported, confirming the coexistence of competing phases over the doping range in which colossal magnetoresistance is observed. We also find that magnetic phase separation in the form of domains appears to be an intrinsic phenomenon at high pressure.

  19. Magnetically separable hybrid CdS-TiO2-Fe3O4 nanomaterial: Enhanced photocatalystic activity under UV and visible irradiation

    NASA Astrophysics Data System (ADS)

    Bian, Xiaofang; Hong, Kunquan; Liu, Liqing; Xu, Mingxiang

    2013-09-01

    Magnetically separable photocatalyst of TiO2-CdS-Fe3O4@SiO2 nanocomposite was successfully prepared through a microwave heating method. The products exhibit enhanced photocatalystic activity which is more efficient than that of pure CdS and Degussa P25 TiO2 toward the degradation of RhB under both UV and visible irradiation. This is attributed to the charge separation and transformation from CdS to TiO2. The hysteresis loop of TiO2-CdS-Fe3O4@SiO2 nanocomposite indicates an excellent magnetic property with the saturated magnetization of 9 emu/g. We also show the fast magnetic separation behaviour of the TiO2-CdS-Fe3O4@SiO2 nanocomposite to remove and recycle the photocatalyst from the solution. These indicate TiO2-CdS-Fe3O4@SiO2 nanocomposite is an effective and convenient recyclable photocatalyst.

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

    PubMed Central

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

    2010-01-01

    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

  1. River flood events in Thailand and Bangladesh observed by CryoSat-2

    NASA Astrophysics Data System (ADS)

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

    2015-04-01

    The high along track resolution of the SIRAL altimeter carried on-board CryoSat-2 offers a wide range of unique opportunities for satellite monitoring. This study focuses on the ability of CryoSat-2 to detect the effects of flood events such as increased river levels and inundation of land. Here we study two flood events; the Bangladesh flood event of June 2012 and the flooding in Thailand that lasted between July 2011 and January 2012. The flooding in these areas was caused by abnormal monsoonal rainfall and affected millions of people. We process CryoSat-2 level 1b SAR mode data to derive water levels for the areas and compare these levels before, during and after the flooding events. Other parameters such as the backscatter coefficient and pulse peakiness are also considered. To verify the extent of the flooding observed by CryoSat-2 we compare with independent sources such as Landsat images.

  2. Mechanical Property Characterization of Cryo-Rolled Copper by Miniaturized Disk Bend and Nanoindentation Technique

    NASA Astrophysics Data System (ADS)

    Sharma, Garima; Chatterjee, Arnomitra; Kapoor, Rajeev; Chakravartty, J. K.

    2014-12-01

    The present study reports mechanical behavior of severe plastically deformed pure Cu under cryogenic conditions by miniaturized disk bend test (MDBT) and nanoindentation technique. MDBT is a useful technique to determine mechanical property of miniature samples under multiaxial state of stress. The samples were severely deformed by cryo-rolling upto 75% and 95% reduction. Microstructure evolution of cryo-rolled samples has been characterized using optical and EBSD technique. MDBT was performed on cryo-rolled 10-mm disk of ~200-?m thickness. Nanoindentation tests were also performed on the cryo-rolled samples. The hardness values obtained from nanoindentation tests were compared with yield stress obtained from MDBT. The present study established a good quantitative correlation between the two techniques. Mechanical dynamic parameters; strain rate sensitivity ( m) and activation volume ( V*) determined by MDBT and nanoindentation techniques showed close agreement in the results.

  3. Mechanical Property Characterization of Cryo-Rolled Copper by Miniaturized Disk Bend and Nanoindentation Technique

    NASA Astrophysics Data System (ADS)

    Sharma, Garima; Chatterjee, Arnomitra; Kapoor, Rajeev; Chakravartty, J. K.

    2014-09-01

    The present study reports mechanical behavior of severe plastically deformed pure Cu under cryogenic conditions by miniaturized disk bend test (MDBT) and nanoindentation technique. MDBT is a useful technique to determine mechanical property of miniature samples under multiaxial state of stress. The samples were severely deformed by cryo-rolling upto 75% and 95% reduction. Microstructure evolution of cryo-rolled samples has been characterized using optical and EBSD technique. MDBT was performed on cryo-rolled 10-mm disk of ~200-?m thickness. Nanoindentation tests were also performed on the cryo-rolled samples. The hardness values obtained from nanoindentation tests were compared with yield stress obtained from MDBT. The present study established a good quantitative correlation between the two techniques. Mechanical dynamic parameters; strain rate sensitivity (m) and activation volume (V*) determined by MDBT and nanoindentation techniques showed close agreement in the results.

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

    PubMed

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

    2012-11-01

    Low-dose images obtained by electron cryo-microscopy (cryo-EM) are often affected by blurring caused by sample motion during electron beam exposure, degrading signal especially at high resolution. We show here that we can align frames of movies, recorded with a direct electron detector during beam exposure of rotavirus double-layered particles, thereby greatly reducing image blurring caused by beam-induced motion and sample stage instabilities. This procedure increases the efficiency of cryo-EM imaging and enhances the resolution obtained in three-dimensional reconstructions of the particle. Using movies in this way is generally applicable to all cryo-EM samples and should also improve the performance of midrange electron microscopes that may have limited mechanical stability and beam coherence. PMID:23022349

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

    PubMed Central

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

    2012-01-01

    Summary Low-dose images obtained by electron cryo-microscopy (cryo-EM) are often affected by blurring caused by sample motion during electron beam exposure, degrading signal especially at high resolution. We show here that we can align frames of movies, recorded with a direct electron detector during beam exposure of rotavirus double-layered particles, thereby greatly reducing image blurring caused by beam-induced motion and sample stage instabilities. This procedure increases the efficiency of cryo-EM imaging and enhances the resolution obtained in three-dimensional reconstructions of the particle. Employing movies in this way is generally applicable to all cryo-EM samples and should also improve the performance of mid-range electron microscopes that may have limited mechanical stability and beam coherence. PMID:23022349

  6. Incorporation of aminoacyl-tRNA into the ribosome as seen by cryo-electron microscopy

    Microsoft Academic Search

    Mikel Valle; Andrey Zavialov; Wen Li; Scott M Stagg; Jayati Sengupta; Rikke C Nielsen; Poul Nissen; Stephen C Harvey; Måns Ehrenberg; Joachim Frank

    2003-01-01

    Aminoacyl-tRNAs (aa-tRNAs) are delivered to the ribosome as part of the ternary complex of aa-tRNA, elongation factor Tu (EF-Tu) and GTP. Here, we present a cryo-electron microscopy (cryo-EM) study, at a resolution of ?9 Å, showing that during the incorporation of the aa-tRNA into the 70S ribosome of Escherichia coli, the flexibility of aa-tRNA allows the initial codon recognition and

  7. Bending modes of DNA directly addressed by cryo-electron microscopy of DNA minicircles

    Microsoft Academic Search

    Davide Demurtas; Arnaud Amzallag; Eric J. Rawdon; John H. Maddocks; Jacques Dubochet; Andrzej Stasiak

    2009-01-01

    We use cryo-electron microscopy (cryo-EM) to study the 3D shapes of 94-bp-long DNA minicircles and address the question of whether cyclization of such short DNA molecules necessitates the forma- tion of sharp, localized kinks in DNA or whether the necessary bending can be redistributed and accomplished within the limits of the elastic, stan- dard model of DNA flexibility. By comparing

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

    PubMed Central

    Grigorieff, Nikolaus; Harrison, Stephen C.

    2011-01-01

    Nine different near-atomic resolution structures of icosahedral viruses, determined by electron cryo-microscopy and published between early 2008 and late 2010, fulfill predictions made 15 years ago that single-particle cryo-EM techniques could visualize molecular detail at 3 – 4 Å resolution. This review summarizes technical developments, both in instrumentation and in computation, that have led to the new structures, which advance our understanding of virus assembly and cell entry. PMID:21333526

  9. Contrast transfer function correction applied to cryo-electron tomography and sub-tomogram averaging

    Microsoft Academic Search

    Giulia Zanetti; James D. Riches; Stephen D. Fuller; John A. G. Briggs

    2009-01-01

    Cryo-electron tomography together with averaging of sub-tomograms containing identical particles can reveal the structure of proteins or protein complexes in their native environment. The resolution of this technique is limited by the contrast transfer function (CTF) of the microscope. The CTF is not routinely corrected in cryo-electron tomography because of difficulties including CTF detection, due to the low signal to

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

    PubMed

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

    2015-01-01

    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

  11. Integrative Modeling of Biomolecular Complexes: HADDOCKing with Cryo-Electron Microscopy Data.

    PubMed

    van Zundert, Gydo C P; Melquiond, Adrien S J; Bonvin, Alexandre M J J

    2015-05-01

    Protein-protein interactions play a central role in all cellular processes. Insight into their atomic architecture is therefore of paramount importance. Cryo-electron microscopy (cryo-EM) is capable of directly imaging large macromolecular complexes. Unfortunately, the resolution is usually not sufficient for a direct atomic interpretation. To overcome this, cryo-EM data are often combined with high-resolution atomic structures. However, current computational approaches typically do not include information from other experimental sources nor a proper physico-chemical description of the interfaces. Here we describe the integration of cryo-EM data into our data-driven docking program HADDOCK and its performance on a benchmark of 17 complexes. The approach is demonstrated on five systems using experimental cryo-EM data in the range of 8.5-21 Å resolution. For several cases, cryo-EM data are integrated with additional interface information, e.g. mutagenesis and hydroxyl radical footprinting data. The resulting models have high-quality interfaces, revealing novel details of the interactions. PMID:25914056

  12. Extreme magnetic separation of geminal protons in protonated N,N,N'-trimethyl-1,8-diaminonaphthalene. A puzzle of the fourth methyl group.

    PubMed

    Ozeryanskii, Valery A; Pozharskii, Alexander F; Filarowski, Alexander; Borodkin, Gennady S

    2013-05-01

    Monoprotonated N,N,N'-trimethyl-1,8-diaminonaphthalene demonstrates fast exchange of H(in) and H(out) protons, in which a counterion (BF4(-) and Br(-) were tested) participates. The process can be frozen below 185 K revealing a tremendous magnetic separation (up to ?? = 11.6 ppm) of these otherwise equal NH protons with the enzyme-like proton transfer and a ?7 kcal mol(-1) energetic barrier. PMID:23590329

  13. Removal of As(V) and Cr(VI) Ions from Aqueous Solution using a Continuous, Hybrid Field?Gradient Magnetic Separation Device

    Microsoft Academic Search

    Ashish K. Jha; Arijit Bose; Jerome P. Downey

    2006-01-01

    A continuous flow colloidal affinity magnetic separation device is used for the removal of As(V) and Cr(VI) from aqueous solutions. Langmuir isotherms fit the adsorption behavior of the individual ions on Orica MIEX ion exchange particles. In a mixture of equal weight percent As(V) and Cr(VI), the adsorption of As(V) begins only above a critical cut?off concentration, implying preferential adsorption

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

    PubMed

    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

    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

  15. Representation Theoretic Patterns in Three-Dimensional Cryo-Electron Microscopy II—The Class Averaging Problem

    Microsoft Academic Search

    Ronny Hadani; Amit Singer

    2011-01-01

    In this paper we study the formal algebraic structure underlying the intrinsic classification algorithm, recently introduced\\u000a in Singer et al. (SIAM J. Imaging Sci. 2011, accepted), for classifying noisy projection images of similar viewing directions in three-dimensional cryo-electron microscopy\\u000a (cryo-EM). This preliminary classification is of fundamental importance in determining the three-dimensional structure of\\u000a macromolecules from cryo-EM images. Inspecting this algebraic

  16. Cryo-Electron Microscopy Structure of Lactococcal Siphophage 1358 Virion

    PubMed Central

    Spinelli, Silvia; Bebeacua, Cecilia; Orlov, Igor; Tremblay, Denise; Klaholz, Bruno P.

    2014-01-01

    ABSTRACT Lactococcus lactis, a Gram+ lactic acid-producing bacterium used for the manufacture of several fermented dairy products, is subject to infection by diverse virulent tailed phages, leading to industrial fermentation failures. This constant viral risk has led to a sustained interest in the study of their biology, diversity, and evolution. Lactococcal phages now constitute a wide ensemble of at least 10 distinct genotypes within the Caudovirales order, many of them belonging to the Siphoviridae family. Lactococcal siphophage 1358, currently the only member of its group, displays a noticeably high genomic similarity to some Listeria phages as well as a host range limited to a few L. lactis strains. These genomic and functional characteristics stimulated our interest in this phage. Here, we report the cryo-electron microscopy structure of the complete 1358 virion. Phage 1358 exhibits noteworthy features, such as a capsid with dextro handedness and protruding decorations on its capsid and tail. Observations of the baseplate of virion particles revealed at least two conformations, a closed and an open, activated form. Functional assays uncovered that the adsorption of phage 1358 to its host is Ca2+ independent, but this cation is necessary to complete its lytic cycle. Taken together, our results provide the complete structural picture of a unique lactococcal phage and expand our knowledge on the complex baseplate of phages of the Siphoviridae family. IMPORTANCE Phages of Lactococcus lactis are investigated mainly because they are sources of milk fermentation failures in the dairy industry. Despite the availability of several antiphage measures, new phages keep emerging in this ecosystem. In this study, we provide the cryo-electron microscopy reconstruction of a unique lactococcal phage that possesses genomic similarity to particular Listeria phages and has a host range restricted to only a minority of L. lactis strains. The capsid of phage 1358 displays the almost unique characteristic of being dextro handed. Its capsid and tail exhibit decorations that we assigned to nonspecific sugar binding modules. We observed the baseplate of 1358 in two conformations, a closed and an open form. We also found that the adsorption to its host, but not infection, is Ca2+ independent. Overall, this study advances our understanding of the adhesion mechanisms of siphophages. PMID:24872584

  17. Fine Ice Sheet margins topography from swath processing of CryoSat SARIn mode data

    NASA Astrophysics Data System (ADS)

    Gourmelen, N.; Escorihuela, M. J.; Shepherd, A.; Foresta, L.; Muir, A.; Briggs, K.; Hogg, A. E.; Roca, M.; Baker, S.; Drinkwater, M. R.

    2014-12-01

    Reference and repeat-observations of Glacier and Ice Sheet Margin (GISM) topography are critical to identify changes in ice thickness, provide estimates of mass gain or loss and thus quantify the contribution of the cryosphere to sea level change. The lack of such sustained observations was identified in the Integrated Global Observing Strategy (IGOS) Cryosphere Theme Report as a major shortcoming. Conventional altimetry measurements over GISMs exist, but coverage has been sparse and characterized by coarse ground resolution. Additionally, and more importantly, they proved ineffective in the presence of steep slopes, a typical feature of GISM areas. Since the majority of Antarctic and Greenland ice sheet mass loss is estimated to lie within 100 km from the coast, but only about 10% is surveyed, there is the need for more robust and dense observations of GISMs, in both time and space. The ESA Altimetry mission CryoSat aims at gaining better insight into the evolution of the Cryosphere. CryoSat's revolutionary design features a Synthetic Interferometric Radar Altimeter (SIRAL), with two antennas for interferometry. The corresponding SAR Interferometer (SARIn) mode of operation increases spatial resolution while resolving the angular origin of off-nadir echoes occurring over sloping terrain. The SARIn mode is activated over GISMs and the elevation for the Point Of Closest Approach (POCA) is a standard product of the CryoSat mission. Here we present an approach for more comprehensively exploiting the SARIn mode of CryoSat and produce an ice elevation product with enhanced spatial resolution compared to standard CryoSat-2 height products. In this so called L2-swath processing approach, the full CryoSat waveform is exploited under specific conditions of signal and surface characteristics. We will present the rationale, validation exercises and preliminary results from the Eurpean Space Agency's STSE CryoTop study over selected test regions of the margins of the Greenland and Antarctic Ice Sheets.

  18. Workshop on the validation and modeling of electron cryo-microscopy structures of biological nanomachines.

    PubMed

    Ludtke, Steven J; Lawson, Catherine L; Kleywegt, Gerard J; Berman, Helen M; Chiu, Wah

    2011-01-01

    Electron cryo-microscopy (cryoEM) is a rapidly maturing methodology in structural biology, which now enables the determination of 3D structures of molecules, macromolecular complexes and cellular components at resolutions as high as 3.5Å, bridging the gap between light microscopy and X-ray crystallography/NMR. In recent years structures of many complex molecular machines have been visualized using this method. Single particle reconstruction, the most widely used technique in cryoEM, has recently demonstrated the capability of producing structures at resolutions approaching those of X-ray crystallography, with over a dozen structures at better than 5 Å resolution published to date. This method represents a significant new source of experimental data for molecular modeling and simulation studies. CryoEM derived maps and models are archived through EMDataBank.org joint deposition services to the EM Data Bank (EMDB) and Protein Data Bank (PDB), respectively. CryoEM maps are now being routinely produced over the 3 - 30 Å resolution range, and a number of computational groups are developing software for building coordinate models based on this data and developing validation techniques to better assess map and model accuracy. In this workshop we will present the results of the first cryoEM modeling challenge, in which computational groups were asked to apply their tools to a selected set of published cryoEM structures. We will also compare the results of the various applied methods, and discuss the current state of the art and how we can most productively move forward. PMID:21121065

  19. A national facility for biological cryo-electron microscopy

    SciTech Connect

    Saibil, Helen R., E-mail: h.saibil@mail.cryst.bbk.ac.uk [Birkbeck College, Malet Street, London WC1E 7HX (United Kingdom); Grünewald, Kay [University of Oxford, Oxford OX3 7BN (United Kingdom); Stuart, David I. [University of Oxford, Oxford OX3 7BN (United Kingdom); Diamond Light Source, Didcot OX11 0DE (United Kingdom); Birkbeck College, Malet Street, London WC1E 7HX (United Kingdom)

    2015-01-01

    This review provides a brief update on the use of cryo-electron microscopy for integrated structural biology, along with an overview of the plans for the UK national facility for electron microscopy being built at the Diamond synchrotron. Three-dimensional electron microscopy is an enormously powerful tool for structural biologists. It is now able to provide an understanding of the molecular machinery of cells, disease processes and the actions of pathogenic organisms from atomic detail through to the cellular context. However, cutting-edge research in this field requires very substantial resources for equipment, infrastructure and expertise. Here, a brief overview is provided of the plans for a UK national three-dimensional electron-microscopy facility for integrated structural biology to enable internationally leading research on the machinery of life. State-of-the-art equipment operated with expert support will be provided, optimized for both atomic-level single-particle analysis of purified macromolecules and complexes and for tomography of cell sections. The access to and organization of the facility will be modelled on the highly successful macromolecular crystallography (MX) synchrotron beamlines, and will be embedded at the Diamond Light Source, facilitating the development of user-friendly workflows providing near-real-time experimental feedback.

  20. Breaking the Radiation Damage Limit with Cryo-SAXS

    PubMed Central

    Meisburger, Steve P.; Warkentin, Matthew; Chen, Huimin; Hopkins, Jesse B.; Gillilan, Richard E.; Pollack, Lois; Thorne, Robert E.

    2013-01-01

    Small angle x-ray scattering (SAXS) is a versatile and widely used technique for obtaining low-resolution structures of macromolecules and complexes. SAXS experiments measure molecules in solution, without the need for labeling or crystallization. However, radiation damage currently limits the application of SAXS to molecules that can be produced in microgram quantities; for typical proteins, 10–20 ?L of solution at 1 mg/mL is required to accumulate adequate signal before irreversible x-ray damage is observed. Here, we show that cryocooled proteins and nucleic acids can withstand doses at least two orders of magnitude larger than room temperature samples. We demonstrate accurate T = 100 K particle envelope reconstructions from sample volumes as small as 15 nL, a factor of 1000 smaller than in current practice. Cryo-SAXS will thus enable structure determination of difficult-to-express proteins and biologically important, highly radiation-sensitive proteins including light-activated switches and metalloenzymes. PMID:23332075

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

    NASA Astrophysics Data System (ADS)

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

    2013-08-01

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

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

    PubMed

    Kiss, Gabriella; Chen, Xuemin; Brindley, Melinda A; Campbell, Patricia; Afonso, Claudio L; Ke, Zunlong; Holl, Jens M; Guerrero-Ferreira, Ricardo C; Byrd-Leotis, Lauren A; Steel, John; Steinhauer, David A; Plemper, Richard K; Kelly, Deborah F; Spearman, Paul W; Wright, Elizabeth R

    2014-02-01

    Electron microscopy (EM), cryo-electron microscopy (cryo-EM), and cryo-electron tomography (cryo-ET) 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 pathogenic viruses to humans. The purification of enveloped viruses from cell culture presents certain challenges. Specifically, the inclusion of host-membrane-derived vesicles, the complete destruction of the viruses, and the disruption of the internal architecture of individual virus particles. Here, we present a strategy for capturing enveloped viruses on affinity grids (AG) for use in both conventional EM and cryo-EM/ET applications. We examined the utility of AG for the selective capture of human immunodeficiency virus virus-like particles, influenza A, and measles virus. We applied nickel-nitrilotriacetic acid lipid layers in combination with molecular adaptors to selectively adhere the viruses to the AG surface. This further development of the AG method may prove essential for the gentle and selective purification of enveloped viruses directly onto EM grids for ultrastructural analyses. PMID:24279992

  3. The use of amphipathic polymers for cryo electron microscopy of NADH:ubiquinone oxidoreductase (complex I).

    PubMed

    Flötenmeyer, Matthias; Weiss, Hanns; Tribet, Christophe; Popot, Jean-Luc; Leonard, Kevin

    2007-09-01

    In the three-dimensional (3D) structure determination of macromolecules, cryo electron microscopy (cryo-EM) is an important method for obtaining micrographs of unstained specimens for the single-particle reconstruction approach. For cryo-EM, proteins are fixed in a frozen hydrated state by quick-freezing in a thin water layer on a holey carbon film. Cryo-EM of detergent-solubilized membrane proteins is hindered by the fact that detergents reduce the surface tension of water, so that it is difficult to control the ice thickness and the distribution of protein. Amphipols are a new class of amphipathic polymers designed to handle membrane proteins in aqueous solutions under particularly mild conditions. Amphipol A8-35 stabilizes NADH:ubiquinone oxidoreductase (complex I) from Neurospora crassa and keeps it water-soluble in the absence of free detergent. Electron microscope images of quick-frozen complex I/A8-35 samples were used for computer-based single-particle averaging and 3D reconstruction, and the reconstruction of unstained frozen-hydrated particles compared with previous detergent-based reconstructions. The potential of amphipols for cryo-EM is discussed. PMID:17760617

  4. Cryo-electron microscopy and the amazing race to atomic resolution.

    PubMed

    Binshtein, Elad; Ohi, Melanie D

    2015-05-26

    Cryo-electron microscopy (cryo-EM), the structural analysis of samples embedded in vitreous ice, is a powerful approach for determining three-dimensional (3D) structures of biological specimens. Over the past two decades, this technique has been used to successfully calculate subnanometer (<10 Å) resolution and, in some cases, near-atomic resolution structures of highly symmetrical and stable complexes such as icosahedral viruses and ribosomes, as well as samples that form ordered two-dimensional or helical arrays. However, determining high-resolution 3D structures of smaller, less symmetrical, and dynamic samples remains a significant challenge. The recent development of electron microscopes with automated data collection capabilities and robust direct electron detection cameras, as well as new powerful image processing algorithms, has dramatically expanded the number of biological macromolecules amenable for study using cryo-EM. In addition, these new technological and computational developments have been used to successfully determine <5 Å resolution 3D structures of samples, such as membrane proteins and complexes with either low or no symmetry, that traditionally were not considered promising candidates for high-resolution cryo-EM. With these exciting new advances, cryo-EM is now on pace to determine atomic resolution 3D structures. PMID:25955078

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

    PubMed

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

    2014-08-12

    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 Mg(2+) 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(-)/Å(2). 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

  6. Effect of an external magnetic field on a critical point for phase separation in a dusty plasma

    NASA Astrophysics Data System (ADS)

    Avinash, K.; Shukla, P. K.; Merlino, R. L.

    2012-09-01

    The effect of an external magnetic field on a critical point for phase transitions in a dusty plasma is investigated. It is shown that the ambient magnetic field increases the effective hard core radius of dust particles, which, in turn, would affect a critical point in terms of the Coulomb coupling parameter and the ratio between the inter-dust grain spacing and the dusty plasma Debye radius. The present result may be useful in understanding the phenomenon of liquid-vapor phase transitions in laboratory dusty plasmas that are held in an external magnetic field.

  7. Magnetic separation for a continuous solar-two-step thermochemical cycle for solar hydrogen/CO production using ferrites

    E-print Network

    Arias, Francisco J.; Parks, Geoffrey T.

    2015-05-21

    T Temperature V Volume of particle z Axial coordinate Greek symbols a Ratio of Zeeman energy to thermal energy l0 Vacuum permeability lB Bohr magneton q Density particle H Curie temperature Subscripts c Cavity dd dipole–dipole g Gravitational mag Magnetic... of the magnetic particles during the combined effect of these forces must be less than the characteristic length of the cavity, or mathematically: F~g þ F~mag #2; #3; t2 2m #8; lc; ð15Þ where m ¼ qV is the particle mass, t the time for which the magnetic field...

  8. Hybrid Graphene Oxide Based Plasmonic-Magnetic Multifunctional Nanoplatform for Selective Separation and Label-Free Identification of Alzheimer's Disease Biomarkers.

    PubMed

    Demeritte, Teresa; Viraka Nellore, Bhanu Priya; Kanchanapally, Rajashekhar; Sinha, Sudarson Sekhar; Pramanik, Avijit; Chavva, Suhash Reddy; Ray, Paresh Chandra

    2015-06-24

    Despite intense efforts, Alzheimer's disease (AD) is one of the top public health crisis for society even at 21st century. Since presently there is no cure for AD, early diagnosis of possible AD biomarkers is crucial for the society. Driven by the need, the current manuscript reports the development of magnetic core-plasmonic shell nanoparticle attached hybrid graphene oxide based multifunctional nanoplatform which has the capability for highly selective separation of AD biomarkers from whole blood sample, followed by label-free surface enhanced Raman spectroscopy (SERS) identification in femto gram level. Experimental ELISA data show that antibody-conjugated nanoplatform has the capability to capture more than 98% AD biomarkers from the whole blood sample. Reported result shows that nanoplatform can be used for SERS "fingerprint" identification of ?-amyloid and tau protein after magnetic separation even at 100 fg/mL level. Experimental results indicate that very high sensitivity achieved is mainly due to the strong plasmon-coupling which generates huge amplified electromagnetic fields at the "hot spot". Experimental results with nontargeted HSA protein, which is one of the most abundant protein components in cerebrospinal fluid (CSF), show that multifunctional nanoplatform based AD biomarkers separation and identification is highly selective. PMID:26027901

  9. Bifunctional magnetic nanobeads for sensitive detection of avian influenza A (H7N9) virus based on immunomagnetic separation and enzyme-induced metallization.

    PubMed

    Wu, Zhen; Zhou, Chuan-Hua; Chen, Jian-Jun; Xiong, Chaochao; Chen, Ze; Pang, Dai-Wen; Zhang, Zhi-Ling

    2015-06-15

    Bifunctional magnetic nanobeads (bi-MBs) were fabricated by co-immobilizing target recognition molecules and signal molecules on a magnetic nanobead surface, which were used as both separation and enrichment carriers and signal carriers. The bi-MBs could capture and separate avian influenza A (H7N9) virus (H7N9 AIV) from complex samples efficiently based on the specific reaction between antigen-antibody and their good magnetic response, which simplified sample pretreatment and saved the detection time. Taking advantages of their high surface to volume ratio and rich surface functional groups, multiple alkaline phosphatase (ALP) signal molecules were tethered on the surface of bi-MBs which greatly amplified the detection signal. As an efficient signal amplification strategy, enzyme-induced metallization had been integrated with bi-MBs and anodic stripping voltammetry to construct an ultrasensitive electrochemical immunosensor for H7N9 AIV detection. Under the optimal conditions, the introduction of bi-MBs could amplify the detection signal in about four times compared with the same immunoassay without MBs, and the method showed a wide linear range of 0.01-20 ng/mL with a detection limit of 6.8 pg/mL. The electrochemical immunosensor provides a simple and reliable platform with high sensitivity and selectivity which shows great potential in early diagnosis of diseases. PMID:25643598

  10. Popcorn-shaped magnetic core-plasmonic shell multifunctional nanoparticles for the targeted magnetic separation and enrichment, label-free SERS imaging, and photothermal destruction of multidrug-resistant bacteria.

    PubMed

    Fan, Zhen; Senapati, Dulal; Khan, Sadia Afrin; Singh, Anant Kumar; Hamme, Ashton; Yust, Brian; Sardar, Dhiraj; Ray, Paresh Chandra

    2013-02-18

    Over the last few years, one of the most important and complex problems facing our society is treating infectious diseases caused by multidrug-resistant bacteria (MDRB), by using current market-existing antibiotics. Driven by this need, we report for the first time the development of the multifunctional popcorn-shaped iron magnetic core-gold plasmonic shell nanotechnology-driven approach for targeted magnetic separation and enrichment, label-free surface-enhanced Raman spectroscopy (SERS) detection, and the selective photothermal destruction of MDR Salmonella DT104. Due to the presence of the "lightning-rod effect", the core-shell popcorn-shaped gold-nanoparticle tips provided a huge field of SERS enhancement. The experimental data show that the M3038 antibody-conjugated nanoparticles can be used for targeted separation and SERS imaging of MDR Salmonella DT104. A targeted photothermal-lysis experiment, by using 670 nm light at 1.5 W cm(-2) for 10 min, results in selective and irreparable cellular-damage to MDR Salmonella. We discuss the possible mechanism and operating principle for the targeted separation, label-free SERS imaging, and photothermal destruction of MDRB by using the popcorn-shaped magnetic/plasmonic nanotechnology. PMID:23296491

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

    SciTech Connect

    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

    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.

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

    PubMed Central

    2013-01-01

    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

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

    E-print Network

    Boyer, Edmond

    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

  14. Visualization of macromolecular complexes using cryo-electron microscopy with FEI Tecnai transmission electron microscopes

    PubMed Central

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

    2009-01-01

    This protocol details the steps used for visualizing the frozen-hydrated grids as prepared following the accompanying protocol entitled ‘Preparation of macromolecular complexes for visualization using cryo-electron microscopy.’ This protocol describes how to transfer the grid to the microscope using a standard cryo-transfer holder or, alternatively, using a cryo-cartridge loading system, and how to collect low-dose data using an FEI Tecnai transmission electron microscope. This protocol also summarizes and compares the various options that are available in data collection for three-dimensional (3D) single-particle reconstruction. These options include microscope settings, choice of detectors and data collection strategies both in situations where a 3D reference is available and in the absence of such a reference (random-conical and common lines). PMID:18274535

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

    SciTech Connect

    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

    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.

  16. Fabs enable single particle cryoEM studies of small proteins

    PubMed Central

    Wu, Shenping; Avila-Sakar, Agustin; Kim, JungMin; Booth, David S.; Greenberg, Charles H.; Rossi, Andrea; Liao, Maofu; Li, Xueming; Alian, Akram; Griner, Sarah L.; Juge, Narinobu; Yu, Yadong; Mergel, Claudia M.; Chaparro-Riggers, Javier; Strop, Pavel; Tampé, Robert; Edwards, Robert H.; Stroud, Robert M.; Craik, Charles S.; Cheng, Yifan

    2012-01-01

    Summary In spite of its recent achievements, the technique of single particle electron cryomicroscopy (cryoEM) has not been widely used to study proteins smaller than 100kDa, although it is a highly desirable application of this technique. One fundamental limitation is that images of small proteins embedded in vitreous ice do not contain adequate features for accurate image alignment. We describe a general strategy to overcome this limitation by selecting a fragment antigen binding (Fab) to form a stable and rigid complex with a target protein, thus providing a defined feature for accurate image alignment. Using this approach, we determined a three-dimensional structure of a ~65 kDa protein by single particle cryoEM. Because Fabs can be readily generated against a wide range of proteins by phage display, this approach is generally applicable to study many small proteins by single particle cryoEM. PMID:22483106

  17. Greenland 2012 melt event effects on CryoSat-2 radar altimetry

    NASA Astrophysics Data System (ADS)

    Nilsson, Johan; Vallelonga, Paul; Simonsen, Sebastian B.; Sørensen, Louise Sandberg; Forsberg, René; Dahl-Jensen, Dorthe; Hirabayashi, Motohiro; Goto-Azuma, Kumiko; Hvidberg, Christine S.; Kjær, Helle A.; Satow, Kazuhide

    2015-05-01

    CryoSat-2 data are used to study elevation changes over an area in the interior part of the Greenland Ice Sheet during the extreme melt event in July 2012. The penetration of the radar signal into dry snow depends heavily on the snow stratigraphy, and the rapid formation of refrozen ice layers can bias the surface elevations obtained from radar altimetry. We investigate the change in CryoSat-2 waveforms and elevation estimates over the melt event and interpret the findings by comparing in situ surface and snow pit observations from the North Greenland Eemian Ice Drilling Project camp. The investigation shows a major transition of scattering properties around the area, and an apparent elevation increase of 56 ± 26 cm is observed in reprocessed CryoSat-2 data. We suggest that this jump in elevation can be explained by the formation of a refrozen melt layer that raised the reflective surface, introducing a positive elevation bias.

  18. Structures of viral membrane proteins by high-resolution cryoEM

    PubMed Central

    Zhou, Z Hong

    2015-01-01

    Cryo electron microscopy (cryoEM) has emerged as an excellent tool for resolving high-resolution three-dimensional structures of membrane proteins in a lipid-containing environment with interacting partners. The near atomic resolution structures of Venezuelan equine encephalitis virus and dengue virus revealed transmembrane helices in lipid bilayers, receptor-binding glycosylation moieties, and functionally important interactions between their fusion protein and membrane-anchored chaperone protein. For pleomorphic enveloped viruses, such as human immunodeficiency virus, glycoprotein complexes can be imaged in isolation to reveal molecular interactions at different states. These high-resolution cryoEM structures have clarified important domains not previously resolved by crystallography and illustrate exciting opportunities to visualize viral membrane proteins in their native and possibly transiently stable functional states, thus uncovering mechanisms of action and informing anti-viral strategies. PMID:24799302

  19. Phase separation, ferromagnetism and magnetic irreversibility in La 1- xSr xMn 1- yFe yO 3

    NASA Astrophysics Data System (ADS)

    Zakhvalinskii, V. S.; Laiho, R.; Lashkul, A. V.; Lisunov, K. G.; Lähderanta, E.; Nekrasova, Yu. S.; Petrenko, P. A.

    2011-08-01

    Magnetic susceptibility, ?(T), is investigated in ceramic La1-xSrxMn1-yFeyO3 (LSMFO) samples with x=0.3 and y=0.15-0.25. A ferromagnetic (FM) transition observed in LSMFO is accompanied with an appreciable decrease of the transition temperature with increasing y, which is connected to breaking of the FM double-exchange interaction by doping with Fe. Strong magnetic irreversibility, observed in low (B=10 G) field, gives evidence for frustration of the magnetic state of LSMFO. The FM transition, which is expanded with increasing B, is more pronounced in the samples with y=0.15-0.20 and broadens considerably at y=0.25, where the irreversibility is increased. Well above the transition, ?(T) exhibits a Curie-Weiss asymptotic behavior, yielding very large values of the effective Bohr magneton number per magnetic ion, incompatible with those of Mn or Fe single ions. At y=0.15 and 0.20 a critical behavior of ?-1(T)?(T/TC-1)? in the region of the FM transition is characterized by influence of two different magnetic systems, a 3D percolative one with ?=?p?1.8 and TC=TC(p), and a non-percolative 3D Heisenberg spin system, with ?=?H?1.4 and TC=TC(H), where TC(p)separation, with onset already near the room temperature, leading to generation of nanosize FM particles in the paramagnetic host matrix of LSMFO. The ferromagnetism of LSMFO is attributable to percolation over the system of such particles and generation of large FM clusters, whereas the frustration is governed presumably by a system of smaller weakly-correlated magnetic units, which do not enter the percolative FM clusters.

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

    PubMed

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

    2013-12-01

    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

  1. Fine Ice Sheet margins topography from swath processing of CryoSat SARIn mode data

    NASA Astrophysics Data System (ADS)

    Foresta, Luca; Gourmelen, Noel; Shepherd, Andrew; Escorihuela, Maria Jose; Muir, Alan; Briggs, Kate; Roca, Monica; Baker, Steven; Drinkwater, Mark; Nienow, Pete

    2014-05-01

    Reference and repeat-observations of Glacier and Ice Sheet Margin (GISM) topography are critical to identify changes in ice thickness, provide estimates of mass gain or loss and thus quantify the contribution of the cryosphere to sea level change. The lack of such sustained observations was identified in the Integrated Global Observing Strategy (IGOS) Cryosphere Theme Report as a major shortcoming. Conventional altimetry measurements over GISMs exist, but coverage has been sparse and characterized by coarse ground resolution. Additionally, and more importantly, they proved ineffective in the presence of steep slopes, a typical feature of GISM areas. Since the majority of Antarctic and Greenland ice sheet mass loss is estimated to lie within 100 km from the coast, but only about 10% is surveyed, there is the need for more robust and dense observations of GISMs, in both time and space. The ESA Altimetry mission CryoSat aims at gaining better insight into the evolution of the Cryosphere. CryoSat's revolutionary design features a Synthetic Interferometric Radar Altimeter (SIRAL), with two antennas for interferometry. The corresponding SAR Interferometer (SARIn) mode of operation increases spatial resolution while resolving the angular origin of off-nadir echoes occurring over sloping terrain. The SARIn mode is activated over GISMs and the elevation for the Point Of Closest Approach (POCA) is a standard product of the CryoSat mission. Here we present a new approach for more comprehensively exploiting the SARIn mode of CryoSat and produce an ice elevation product with enhanced spatial resolution compared to standard CryoSat-2 height products. In this so called L2-swath processing approach, the signal beyond the POCA is exploited when signal and surface characteristics are favourable. We will present the rationale, validation exercises and preliminary results from the STSE CryoTop study over selected test regions of the margins of the Greenland and Antarctic Ice Sheets.

  2. A self-consistent two-dimensional resistive fluid theory of field-aligned potential structures including charge separation and magnetic and velocity shear

    NASA Technical Reports Server (NTRS)

    Hesse, Michael; Birn, Joachim; Schindler, Karl

    1990-01-01

    A self-consistent two-fluid theory that includes the magnetic field and shear patterns is developed to model stationary electrostatic structures with field-aligned potential drops. Shear flow is also included in the theory since this seems to be a prominent feature of the structures of interest. In addition, Ohmic dissipation, a Hall term, and pressure gradients in a generalized Ohm's law, modified for cases without quasi-neutrality, are included. In the analytic theory, the electrostatic force is balanced by field-aligned pressure gradients (i.e., thermal effects in the direction of the magnetic field) and by pressure gradients and magnetic stresses in the perpendicular direction. Within this theory, simple examples of applications are presented to demonstrate the kind of solutions resulting from the model. The results show how the effects of charge separation and shear in the magnetic field and the velocity can be combined to form self-consistent structures such as are found to exist above the aurora, suggested also in association with solar flares.

  3. Three Birds with One Fe3O4 Nanoparticle: Integration of Microwave Digestion, Solid Phase Extraction, and Magnetic Separation for Sensitive Determination of Arsenic and Antimony in Fish.

    PubMed

    Jia, Yun; Yu, Huimin; Wu, Li; Hou, Xiandeng; Yang, Lu; Zheng, Chengbin

    2015-06-16

    An environmentally friendly and fast sample treatment approach that integrates accelerated microwave digestion (MWD), solid phase extraction, and magnetic separation into a single step was developed for the determination of arsenic and antimony in fish samples by using Fe3O4 magnetic nanoparticles (MNPs). Compared to conventional microwave digestion, the consumption of HNO3 was reduced significantly to 12.5%, and the digestion time and temperature were substantially decreased to 6 min and 80 °C, respectively. This is largely attributed to Fe3O4 magnetic nanoparticles being a highly effective catalyst for rapid generation of oxidative radicals from H2O2, as well as an excellent absorber of microwave irradiation. Moreover, potential interferences from sample matrices were eliminated because the As and Sb species adsorbed on the nanoparticles were efficiently separated from the digests with a hand-held magnet prior to analysis. Limits of detection for arsenic and antimony were in the range of 0.01-0.06 ?g g(-1) and 0.03-0.08 ?g g(-1) by using hydride generation atomic fluorescence spectrometry, respectively, and further improved to 0.002-0.005 ?g g(-1) and 0.005-0.01 ?g g(-1) when inductively coupled plasma mass spectrometry was used as a detector. The precision of replicate measurements (n = 9) was better than 6% by analyzing 0.1 g test sample spiked with 1 ?g g(-1) arsenic and antimony. The proposed method was validated by analysis of two certified reference materials (DORM-3 and DORM-4) with good recoveries (90%-106%). PMID:25962876

  4. Strain-induced oxygen defect formation and interfacial magnetic phase separation in SrTiO3(001)/La1-xSrxCoO3

    NASA Astrophysics Data System (ADS)

    Leighton, Chris

    2012-02-01

    The remarkable functionality and epitaxial compatibility of complex oxides provides many opportunities for new physics and applications in oxide heterostructures. Perovskite manganites and cobaltites provide excellent examples, being of interest for solid oxide fuel cells, catalysis, ferroelectric RAM, gas sensing, resistive switching memory, and oxide spintronics. However, the same delicate balance between phases that provides this diverse functionality also leads to a serious problem - the difficulty of maintaining desired properties close to the interface with other oxides. Although this problem is widespread, manifests itself in several ways, and could present a significant roadblock to the development of heterostructured devices for oxide electronics, there is no consensus as to its origin, or even whether it is driven by electronic or chemical effects. In this work, using SrTiO3(001)/La1-xSrxCoO3 as a model system, we have combined epitaxial growth via high pressure oxygen sputtering with high resolution x-ray diffraction, atomic resolution electron microscopy and spectroscopy, and detailed magnetic, transport, and neutron scattering measurements to determine the fundamental origin of the deterioration in interfacial transport and magnetism. The effect is found to be due to nanoscopic magnetic phase separation in the near-interface region driven by a significant depletion in interfacial hole doping due to accumulation of O vacancies. This occurs due to a novel mechanism for accommodation of lattice mismatch with the substrate based on formation and long-range ordering of O vacancies, thus providing a fundamental link between strain state and O vacancy density. Further impacts of the O vacancy ordering and interfacial magnetic phase separation, such as formation of a spin-state superlattice and an extraordinary coercivity enhancement, will also be discussed. Work in collaboration with M. Sharma, M. Torija, J. Schmitt, C. He, S. El-Khatib, J. Gazquez, M. Varela, M. Laver and J. Borchers.

  5. l-Cysteine functionalized magnetic nanoparticles (LCMNP): a novel magnetically separable organocatalyst for one-pot synthesis of 2-amino-4H-chromene-3-carbonitriles in water.

    PubMed

    Khalafi-Nezhad, Ali; Nourisefat, Maryam; Panahi, Farhad

    2015-07-01

    In this study, l-cysteine was chemically grafted to magnetic nanoparticles in order to prepare a reusable magnetic material incorporating an amino acid moiety. For this purpose, silica-coated magnetic nanoparticles (Fe3O4@SiO2) were reacted with trimethoxy(vinyl)silane to produce vinyl-functionalized magnetic nanoparticles (VMNP). Reaction of a VMNP substrate with l-cysteine in the presence of azobisisobutyronitrile (AIBN) resulted in the production of l-cysteine-functionalized magnetic nanoparticles (LCMNP). The LCMNP material was characterized using different microscopy and spectroscopy techniques such as FT-IR, XRD, TEM, SEM, EDX, VSM, and elemental analysis. Also, LCMNP was analyzed by thermogravimetric analysis (TGA) in order to determine its thermal behavior. The applicability of the LCMNP material was evaluated in a three-component coupling reaction between a nucleophile, salicylaldehyde and malononitrile as the catalyst for one-pot synthesis of 2-amino-4H-chromene-3-carbonitrile derivatives. The catalyst system showed high catalytic activity in this process and target products were obtained in high isolated yields in water as a green solvent. The LCMNP catalyst was reusable in this reaction at least 7 times with no significant decrease in its catalytic activity. PMID:26098281

  6. Magnetic field dependence of the magnetic phase separation in Pr1-xCaxMnO3 manganites studied by small-angle neutron scattering

    NASA Astrophysics Data System (ADS)

    Saurel, Damien; Brûlet, Annie; Heinemann, André; Martin, Christine; Mercone, Silvana; Simon, Charles

    2006-03-01

    Transport properties of manganese oxides suggest that their colossal magnetoresistance (CMR) is due to percolation between ferromagnetic metallic (FM) clusters in an antiferromagnetic insulating (AFI) matrix. We have studied small-angle neutron scattering under an applied magnetic field in CMR Pr1-xCaxMnO3 crystals for x around 0.33 . Quantitative analysis of the small-angle magnetic neutron scattering shows that the magnetic heterogeneities take place at different scales. At the mesoscopic scale (200nm) , the inhomogeneities correspond to the percolation of the conducting ferromagnetic phase into the insulating phases. It is at the origin of the colossal magnetoresistance of the compound. The other inhomogeneities are nanoscopic: inside the antiferromagnetic phase (AFI) there exist small ferromagnetic clusters. Inside the ferromagnetic phase which exists in the absence of the magnetic field in some compounds and is, in fact, insulating (FI), there also exist small nonferromagnetic objects. No evolution of this nanostructure is observed when the magnetic field is applied. The existence of such nanoscale objects is discussed in relation to the cationic disorder of these compounds.

  7. De novo protein structure determination from near-atomic-resolution cryo-EM maps.

    PubMed

    Wang, Ray Yu-Ruei; Kudryashev, Mikhail; Li, Xueming; Egelman, Edward H; Basler, Marek; Cheng, Yifan; Baker, David; DiMaio, Frank

    2015-04-01

    We present a de novo model-building approach that combines predicted backbone conformations with side-chain fit to density to accurately assign sequence into density maps. This method yielded accurate models for six of nine experimental maps at 3.3- to 4.8-Å resolution and produced a nearly complete model for an unsolved map containing a 660-residue heterodimeric protein. This method should enable rapid and reliable protein structure determination from near-atomic-resolution cryo-electron microscopy (cryo-EM) maps. PMID:25707029

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

    PubMed

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

    2014-03-01

    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

  9. Accuracy analysis of CryoSat-2 SARIn mode data over Antarctica

    NASA Astrophysics Data System (ADS)

    Wang, Fang; Bamber, Jonathan; Cheng, Xiao

    2015-04-01

    In 2010, CryoSat-2 was launched, carrying a unique satellite radar altimetry (SRA) instrument called SAR/Interferometric Radar Altimeter (SIRAL), with the aim of measuring and monitoring sea ice, ice sheets and mountain glaciers. The novel SAR Interferometric mode (SARInM) of CryoSat-2 is designed to improve the accuracy, resolution and geolocation of height measurements over the steeper margins of ice sheets and ice caps. Over these areas, it employs the synthetic aperture radar (SAR) capability to reduce the size of the footprint to effectively 450m along track and ~1km across track implemented from an airborne prototype originally termed a delay-Doppler altimeter. Additionally, CryoSat-2 used the phase difference between its two antennas to estimate surface slope in the across-track direction and identify the point of closed approach directly. The phase difference is 2pi for a surface slope of approximately 1deg. If the slope is above this threshold, the tracked surface in the returned waveform may be not the point of closed approach causing an error in slope correction. For this reason, the analysis was limited to slopes of 1deg or less in this study. We used extensive coverage of Antarctica provided by the ICESat laser altimeter mission between 2003 and 2009 to assess the accuracy of SARInM data. We corrected for changes in elevations due to the interval between the acquisition of the ICESat and CryoSat-2 data (from July 2010 and December 2013). Two methods were used: (1) the ICESat point was compared with a DEM derived from CryoSat-2 data (Point-to-DEM; PtoDEM), and (2) the ICESat point was compared with a CryoSat-2 point directly (Point-to-Point; PtoP). For PtoDEM, CryoSat-2 elevations were interpolated onto a regular 1km polar stereographic grid with a standard parallel of 71°S, using ordinary kriging. For PtoP, the maximum distance between a CryoSat-2 point location and ICESat point location was set to 35m. For the areas with slopes less than 0.2deg, the mean differences (ICESat minus CryoSat-2) are less than 1.5m, and standard derivation (?) below 3m. However, the mean differences over Filchner Ronne and Ross Ice Shelf are generally greater than 1m, and differences over Larsen C and Amery Ice Shelf are generally below 1m or negative. The known range biases amount to 0.67m from ESA. The remaining bias over the ice shelves of about 43-53cm is estimated as the average radar penetration depth for the retracker used in the ESA Level 2 processing chain, which is different over these four ice shelves. The strong relationship between firn density and remaining bias is appeared in the four ice shelves and the different backscattering power from the volume scattering in the tailing edge was found in four ice shelves from CryoSat-2 Level 1B data. The accuracy of CryoSat-2 SARInM data over Antarctica was related to the surface slope and roughness and decreased with the slope and roughness increasing.

  10. Magnetically-Separable and Highly-Stable Enzyme System Based on Crosslinked Enzyme Aggregates Shipped in Magnetite-Coated Mesoporous Silica

    SciTech Connect

    Lee, Jinwoo; Na, Hyon Bin; Kim, Byoung Chan; Lee, Jin Hyung; Lee, Byoungsoo; Kwak, Ja Hun; Hwang, Yosun; Park, Je-Geun; Gu, Man Bock; Kim, Jaeyun; Joo, Jin; Shin, Chae-Ho; Grate, Jay W.; Hyeon, Taeghwan; Kim, Jungbae

    2009-10-15

    Magnetically-separable and highly-stable enzyme system was developed by adsorption of enzymes in superparamagnetic hierarchically ordered mesocellular mesoporous silica (M-HMMS) and subsequent enzyme crosslinking. Superparamagnetic nanoparticles were homogeneously incorporated into hierarchically-ordered mesocellular mesoporous silica (HMMS) by the decomposition of preformed iron propionate complex. The size of incorporated superparamagnetic 15 nanoparticles was around 5 nm, generating a magnetically separable host with high pore volumes and large pores (M-HMMS). ?-chymotrypsin (CT) was adsorbed into M-HMMS with high loading (~30 wt%) in less than 30 minutes. Glutaraldehyde (GA) treatment of adsorbed CT resulted in nanometer scale crosslinked enzyme aggregates in M-HMMS (CLEA-M). The activity of these CT aggregates in M-HMMS (CLEA-M-CT) was 34 times than that of simply adsorbed CT in M20 HMMS, due to an effective prevention of enzyme leaching during washing via a ship-in-a-bottle approach. CLEA-M-CT maintained the intial activity not only under shaking (250 rpm) for 30 days, but also under recycled uses of 35 times. The same approach was employed for the synthesis of CLEA-M of lipase (CLEA-M-LP), and proven to be effective in improving the loading, activity, and stability of enzyme when compared to those of adsorbed LP in M-HMMS.

  11. Technical aspects: development, manufacture and installation of a cryo-cooled HTS coil system for high-resolution in-vivo imaging of the mouse at 1.5 T.

    PubMed

    Ginefri, Jean-Christophe; Poirier-Quinot, Marie; Girard, Olivier; Darrasse, Luc

    2007-09-01

    Signal-to-noise ratio improvement is of major importance to achieve microscopic spatial resolution in magnetic resonance experiments. Magnetic resonance imaging of small animals is particularly concerned since it typically requires voxels of less than (100 microm)(3) to observe the small anatomical structures having size reduction by a factor of more than 10 as compared to human being. The signal-to-noise ratio can be increased by working at high static magnetic field strengths, but the biomedical interest of such high-field systems may be limited due to field-dependent contrast mechanisms and severe technological difficulties. An alternative approach that allows working in clinical imaging system is to improve the sensitivity of the radio-frequency receiver coil. This can be done using small cryogenically operated coils made either of copper or high-temperature superconducting material. We report the technological development of cryo-cooled superconducting coils for high-resolution imaging in a whole-body magnetic resonance scanner operating at 1.5 T. The technological background supporting this development is first addressed, including HTS coil design, simulation tools, cryogenic mean description and electrical characterization procedure. To illustrate the performances of superconducting coils for magnetic resonance imaging at intermediate field strength, in-vivo mouse images of various anatomic sites acquired with a 12 mm diameter cryo-cooled superconducting coil are presented. PMID:17720564

  12. A facile co-gelation route to synthesize FeCo\\/carbon nanocomposites and their application as magnetically separable adsorber

    Microsoft Academic Search

    Zhongli Wang; Xiaojuan Liu; Minfeng Lv; Kuiyue Yang; Jian Meng

    2011-01-01

    A new kind of magnetic porous FeCo\\/carbon nanocomposites was successfully synthesized by using a facile co-gelation sol–gel route. The sol–gel process of this route started from an ethanol solution containing teraethylorthosilicate (TEOS), furfuryl alcohol (FA), and metal nitrates. With the evaporation of solvent, the weak acidity produced from hydrolysis of metal nitrates simultaneously catalyzed the polymerization of FA and the

  13. Magnetic surface anisotropies in NiFe-alloy films: separation of intrinsic Néel-type from strain relaxation contributions

    Microsoft Academic Search

    U. Gradmann; H. J Elmers

    1999-01-01

    Magnetic surface anisotropies (MSA) in NiFe\\/Cu(111) films were investigated experimentally, for varying compositions of the NiFe alloy. By restricting the measurements to the pseudomorphic range, the pure intrinsic Néel-type anisotropy could be isolated without strain relaxation contributions. The intrinsic MSA of the xNi(1?x)Fe\\/Cu(111) interface varies linearly with composition x between easy plane for pure Ni to perpendicular for x=60 and

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

    Microsoft Academic Search

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

    2010-01-01

    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

  15. Second-order uniform dynamic susceptibility of lightly oxygenated La 2CuO 4+ x single crystals and peculiarity of their magnetic properties at phase separation

    NASA Astrophysics Data System (ADS)

    Lazuta, A. V.; Ryzhov, V. A.; Larionov, I. I.; Arbuzova, T. I.

    1998-01-01

    We report a study of the second order dynamic susceptibility in parallel static and alternating magnetic fields of three lightly oxygenated single crystals of La 2CuO 4+ x ( x<0.03) with different TN ( TN1?222 K, TN2?272 K and TN3?243 K). The response of all the samples reveals common features which are characteristic of an antiferromagnet with a weak ferromagnetism (WF). These new magnetic properties are attributed to the oxygen-rich phase forming in the course of the phase separation. We show that the WF can be related to out-of CuO 2 plane ordering (staging) of the interstitial oxygen. The response of crystals N1 and N3 is observed in the vicinity of TN and exhibits a critical enhancement. A simple model of WF domain is presented which allows us to describe quantitatively the H-dependence of the signal of crystal N3 above TN. It provides a basis for a comparative analysis of the data on N1 and N3 crystals. The response of crystal N2 is found below TN. In this case its peculiarities reflect change and destruction of initial magnetic ordering in the forming oxygen-rich phase.

  16. A graph theory method for determination of cryo-EM image focuses , Fei Guo, Zheng Liu

    E-print Network

    Jiang, Wen

    of micrograph focuses is essential for averaging multiple images to reach high- resolution 3-D reconstructions for different images. Here we have developed a novel graph theory based method in which the rotational averageA graph theory method for determination of cryo-EM image focuses Wen Jiang , Fei Guo, Zheng Liu

  17. 70Cryo-testing the Webb Space Telescope ISIM The Webb Space Telescope, to

    E-print Network

    , or the Integrated Science Instrument Module Flight Structure, will serve as the structural "heart" of the James Webb70Cryo-testing the Webb Space Telescope ISIM The Webb Space Telescope, to be launched in 2014 by the Webb Space Telescope in 2014. The instruments are very much like `high-tech' digital cameras that can

  18. Protein Secondary Structure Determination by Constrained Single-Particle Cryo-Electron Tomography

    PubMed Central

    Bartesaghi, Alberto; Lecumberry, Federico; Sapiro, Guillermo; Subramaniam, Sriram

    2012-01-01

    SUMMARY Cryo-electron microscopy (cryo-EM) is a powerful technique for 3D structure determination of protein complexes by averaging information from individual molecular images. The resolutions that can be achieved with single-particle cryo-EM are frequently limited by inaccuracies in assigning molecular orientations based solely on 2D projection images. Tomographic data collection schemes, however, provide powerful constraints that can be used to more accurately determine molecular orientations necessary for 3D reconstruction. Here, we propose “constrained single-particle tomography” as a general strategy for 3D structure determination in cryo-EM. A key component of our approach is the effective use of images recorded in tilt series to extract high-resolution information and correct for the contrast transfer function. By incorporating geometric constraints into the refinement to improve orientational accuracy of images, we reduce model bias and overrefinement artifacts and demonstrate that protein structures can be determined at resolutions of ~8 Å starting from low-dose tomographic tilt series. PMID:23217682

  19. Cryo-EM of Viruses 345 From: Methods in Molecular Biology, vol. 369

    E-print Network

    Jiang, Wen

    and their suppliers used in our Center are listed: 1. Quantifoil® R2/2 grids (Quantifoil Micro Tools GmbH, Germany). 2 gun with cryo-stage and low dose kit. 6. Gatan or Tietz 4K × 4K CCD camera for direct digital

  20. Direct electron detection yields cryo-EM reconstructions at resolutions beyond ¾ Nyquist frequency

    PubMed Central

    Bammes, Benjamin E.; Rochat, Ryan H.; Jakana, Joanita; Chen, Dong-Hua; Chiu, Wah

    2012-01-01

    One limitation in electron cryo-microscopy (cryo-EM) is the inability to recover high-resolution signal from the image-recording media at the full-resolution limit of the transmission electron microscope. Direct electron detection using CMOS-based sensors for digitally recording images has the potential to alleviate this shortcoming. Here, we report a practical performance evaluation of a Direct Detection Device (DDD) for biological cryo-EM at two different microscope voltages: 200 and 300 kV. Our DDD images of amorphous and graphitized carbon show strong per-pixel contrast with image resolution near the theoretical sampling limit of the data. Single-particle reconstructions of two frozen-hydrated bacteriophages, P22 and ?15, establish that the DDD is capable of recording usable signal for 3-D reconstructions at about 4/5 of the Nyquist frequency, which is a vast improvement over the performance of conventional imaging media. We anticipate the unparalleled performance of this digital recording device will dramatically benefit cryo-EM for routine tomographic and single-particle structural determination of biological specimens. PMID:22285189

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

    PubMed Central

    Guo, Fei; Jiang, Wen

    2014-01-01

    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

  2. Helium Cryo Testing of a SLMS(TM) (Silicon Lightweight Mirrors) Athermal Optical Assembly

    NASA Technical Reports Server (NTRS)

    Jacoby, Marc T.; Goodman, William A.; Stahl, H. Philip; Keys, Andrew S.; Reily, Jack C.; Eng, Ron; Hadaway, James B.; Hogue, William D.; Kegley, Jeffrey R.; Siler, Richard

    2003-01-01

    SLMS (TM) a thermal technology has been demonstrated in the small 4-foot helium cryogenic test chamber located at the NASA/MSFC X-Ray Calibration Facility (XRCF). A SLMS (TM) Ultraviolet Demonstrator Mirror (UVDM) produced by Schafer under a NASA/MSFC Phase I SBIR was helium cryo tested both free standing and bonded to a Schafer designed prototype carbon fiber reinforced silicon carbide (Cesic) mount. Surface figure data was obtained with a test measurement system that featured an Instantaneous Phase Interferometer (IPI) by ADE Phase Shift. The test measurement system s minimum resolvable differential figure deformation and possible contributions from test chamber ambient to cryo window deformation are under investigation. The free standing results showed differential figure deformation of 10.4 nm rms from 295K to 27K and 3.9 nm rms after one cryo cycle. The surface figure of the UVDM degraded by lambda/70 rms HeNe once it was bonded to the prototype Cesic mount. The change was due to a small astigmatic aberration in the rototype Cesic mount due to lack of finish machining and not the bonding technique. This effect was seen in SLMST (TM) optical assembly results, which showed differential figure deformation of 46.5 nm rms from 294K to 27K, 42.9 nm rms from 294K to 77K, 28.0 nm rms from 294K to 193K and 6.2 nm rms after one cryo cycle.

  3. Adaptation of Cryo-Sectioning for IEM Labeling of Asymmetric Samples: A Study Using Caenorhabditis elegans.

    PubMed

    Nicolle, Ophélie; Burel, Agnès; Griffiths, Gareth; Michaux, Grégoire; Kolotuev, Irina

    2015-08-01

    Cryo-sectioning procedures, initially developed by Tokuyasu, have been successfully improved for tissues and cultured cells, enabling efficient protein localization on the ultrastructural level. Without a standard procedure applicable to any sample, currently existing protocols must be individually modified for each model organism or asymmetric sample. Here, we describe our method that enables reproducible cryo-sectioning of Caenorhabditis elegans larvae/adults and embryos. We have established a chemical-fixation procedure in which flat embedding considerably simplifies manipulation and lateral orientation of larvae or adults. To bypass the limitations of chemical fixation, we have improved the hybrid cryo-immobilization-rehydration technique and reduced the overall time required to complete this procedure. Using our procedures, precise cryo-sectioning orientation can be combined with good ultrastructural preservation and efficient immuno-electron microscopy protein localization. Also, GFP fluorescence can be efficiently preserved, permitting a direct correlation of the fluorescent signal and its subcellular localization. Although developed for C. elegans samples, our method addresses the challenge of working with small asymmetric samples in general, and thus could be used to improve the efficiency of immuno-electron localization in other model organisms. PMID:25858477

  4. Cryo-EM Analysis Reveals New Insights into the Mechanism of Action

    E-print Network

    Tong, Liang

    : mvalle@cicbiogune.es DOI 10.1016/j.str.2010.07.008 SUMMARY Pyruvate carboxylase (PC) is a conserved Pyruvate carboxylase (PC) is a biotin-containing multifunctional enzyme (EC 6.4.1.1) that carboxylatesStructure Article Cryo-EM Analysis Reveals New Insights into the Mechanism of Action of Pyruvate

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

    E-print Network

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

    2015-01-01

    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...

  6. Detection of Secondary and Supersecondary Structures of Proteins from Cryo-Electron Microscopy

    E-print Network

    Texas at Austin, University of

    in proteins. Keywords: protein structures detection, electron microscopy, stable/unstable manifolds, criticalDetection of Secondary and Supersecondary Structures of Proteins from Cryo-Electron Microscopy in three-dimensional electron microscopy (3D EM) have enabled the quantitative visualization

  7. Deformed grids for single-particle cryo-electron microscopy of specimens exhibiting a preferred orientation

    PubMed Central

    Liu, Ying; Meng, Xing; Liu, Zheng

    2013-01-01

    For biological samples showing a preferred orientation on the carbon support film of an electron microscope (EM) grid, accurate three-dimensional (3D) reconstructions by single-particle cryo-EM require data collection in which the specimen grids are tilted in the microscope, to obtain adequate numbers of particles that cover the high-degree angular distribution. However, image drift caused by the electron beam interacting with the cryo specimen becomes severe when grids are tilted to high angles (> 30°). We produced deformed grids by applying a deliberate mechanical deformation to EM grids containing a thin carbon film supported by a thick holey carbon film. We applied cryo-EM using deformed grids to the isolated cardiac ryanodine receptor, an ion channel complex known to assume a preferred orientation on the carbon support film. These grids contained more particles having high Euler angle orientations without the need to tilt the specimen grids. Meanwhile, the drifting that was apparent in the images was reduced from that typical of images from tilted regular EM grids. This was achieved by imaging particles in holes close to the deformed areas, where carbon films were locally bent, offering planes of inclination with various angles. The deformed grids improve the efficiency and quality of data collection for single-pahrticle cryo-EM of samples showing a limited range of orientations. PMID:23537848

  8. Tracing beta strands using StrandTwister from cryo-EM density maps at medium resolutions.

    PubMed

    Si, Dong; He, Jing

    2014-11-01

    Major secondary structure elements such as ? helices and ? sheets can be computationally detected from cryoelectron microscopy (cryo-EM) density maps with medium resolutions of 5-10 Å. However, a critical piece of information for modeling atomic structures is missing, because there are no tools to detect ? strands from cryo-EM maps at medium resolutions. We propose a method, StrandTwister, to detect the traces of ? strands through the analysis of twist, an intrinsic nature of a ? sheet. StrandTwister has been tested using 100 ? sheets simulated at 10 Å resolution and 39 ? sheets computationally detected from cryo-EM density maps at 4.4-7.4 Å resolutions. Although experimentally derived cryo-EM maps contain errors, StrandTwister's best detections over 39 cases were able to detect 81.87% of the ? strands, with an overall 1.66 Å two-way distance between the detected and observed ? traces. StrandTwister appears to detect the traces of ? strands on major ? sheets quite accurately, particularly at the central area of a ? sheet. PMID:25308866

  9. MSFC/UAH Full Aperture Cryo-Figure AMSD Modal Characterization

    NASA Technical Reports Server (NTRS)

    Rogers, Ted; Stahl, Phil; Geary, Joe; Russell, J. Kevin (Technical Monitor)

    2002-01-01

    A full-aperture, interferometric method for measuring the modal characteristics of the Advanced Mirror System Demonstrators (AMSDs) will be presented. The method involves stroboscopic surface figure measurement using an interferometer capable of simultaneous phase-shift measurements. Results of bread-board experiments will be presented as well as the plan for cryo measurements of the AMSDs.

  10. Ribosome structures to near-atomic resolution from thirty thousand cryo-EM particles

    PubMed Central

    Bai, Xiao-chen; Fernandez, Israel S; McMullan, Greg; Scheres, Sjors HW

    2013-01-01

    Although electron cryo-microscopy (cryo-EM) single-particle analysis has become an important tool for structural biology of large and flexible macro-molecular assemblies, the technique has not yet reached its full potential. Besides fundamental limits imposed by radiation damage, poor detectors and beam-induced sample movement have been shown to degrade attainable resolutions. A new generation of direct electron detectors may ameliorate both effects. Apart from exhibiting improved signal-to-noise performance, these cameras are also fast enough to follow particle movements during electron irradiation. Here, we assess the potentials of this technology for cryo-EM structure determination. Using a newly developed statistical movie processing approach to compensate for beam-induced movement, we show that ribosome reconstructions with unprecedented resolutions may be calculated from almost two orders of magnitude fewer particles than used previously. Therefore, this methodology may expand the scope of high-resolution cryo-EM to a broad range of biological specimens. DOI: http://dx.doi.org/10.7554/eLife.00461.001 PMID:23427024

  11. Ribosome structures to near-atomic resolution from thirty thousand cryo-EM particles.

    PubMed

    Bai, Xiao-Chen; Fernandez, Israel S; McMullan, Greg; Scheres, Sjors H W

    2013-01-01

    Although electron cryo-microscopy (cryo-EM) single-particle analysis has become an important tool for structural biology of large and flexible macro-molecular assemblies, the technique has not yet reached its full potential. Besides fundamental limits imposed by radiation damage, poor detectors and beam-induced sample movement have been shown to degrade attainable resolutions. A new generation of direct electron detectors may ameliorate both effects. Apart from exhibiting improved signal-to-noise performance, these cameras are also fast enough to follow particle movements during electron irradiation. Here, we assess the potentials of this technology for cryo-EM structure determination. Using a newly developed statistical movie processing approach to compensate for beam-induced movement, we show that ribosome reconstructions with unprecedented resolutions may be calculated from almost two orders of magnitude fewer particles than used previously. Therefore, this methodology may expand the scope of high-resolution cryo-EM to a broad range of biological specimens.DOI:http://dx.doi.org/10.7554/eLife.00461.001. PMID:23427024

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

    PubMed Central

    Zhang, Xing; Zhou, Z. Hong

    2013-01-01

    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

  13. Chapter 3 Exact Signal-Noise Separation by Froissart Doublets in Fast Padé Transform for Magnetic Resonance Spectroscopy

    NASA Astrophysics Data System (ADS)

    Belkic, Dz; Evad

    In the present study, it is demonstrated that the fast padé transform (FPT) is capable of providing the exponential convergence rate (the spectral convergence) for the exact reconstructions of all the spectral parameters from time signals equivalent to the corresponding in vivo free induction decay curves encoded by means of magnetic resonance spectroscopy with short echo times of about 20 ms at the standard clinical magnetic field strength 1.5 T from the brain of a healthy volunteer. Further, it is shown that residual spectra (the difference between the model and input spectra) are a necessary, but not a sufficient, criterion to estimate the error invoked in quantification. Full validation of the performed quantification within the FPT is possible by monitoring stabilization of all the reconstructed spectral parameters as a function of the partial signal length for a fixed bandwidth (this is equivalent to varying the total acquisition time). Moreover, all the converged fundamental frequencies and amplitudes found in this way must further be cross-validated by checking whether they also represent the joint results of both Padé variants, the FPT(+) and the FPT(-), inside and outside the unit circle, as done in the present study. The Froissart doublets (pole-zero cancellations) are used to unequivocally distinguish between genuine and spurious resonances in both noise-free and noise-corrupted time signals. This permits the exact reconstruction of all the genuine spectral parameters including the fundamental frequencies, the corresponding amplitudes, and the true number of physical resonances. The FPT is shown to be able to resolve and quantify tightly overlapped resonances that are abundantly seen in magnetic resonance spectra generated using encoded in vivo time signals. Most importantly, precisely such overlapping resonances are often of critical relevance for diagnostics in clinical oncology.

  14. The high Beta cryo-modules and the associated cryogenic system for the HIE-ISOLDE upgrade at CERN

    NASA Astrophysics Data System (ADS)

    Delruelle, N.; Leclercq, Y.; Pirotte, O.; Ramos, D.; Tibaron, P.; Vandoni, G.; Williams, L.

    2014-01-01

    The major upgrade of the energy and intensity of the existing ISOLDE and REX-ISOLDE radioactive ion beam facilities at CERN requires the replacement of most of the existing ISOLDE post-acceleration equipment by a superconducting linac based on quarter-wave resonators housed together with superconducting solenoids in a series of four high-? and two low-? cryo-modules. As well as providing optimum conditions for physics, the cryo-modules need to function under stringent vacuum and cryogenic conditions. We present the detail design and expected cryogenic performance of the high- ? cryo-module together with the cryogenic supply and distribution system destined to service the complete superconducting linac.

  15. Investigation of Cryo-Cooled Microcoils for MRI

    E-print Network

    Godley, Richard Franklin

    2012-10-19

    When increasing magnetic resonance imaging (MRI) resolution into the micron scale, image signal-to-noise ratio (SNR) can be maintained by using small radiofrequency (RF) coils in close proximity to the sample being imaged. Micro-scale RF coils...

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

    PubMed

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

    2009-11-15

    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

  17. Separation of magnetic field effects on the photoreduction of xanthone with p-aminothiophenol into the effects due to the ? and relaxation mechanisms

    NASA Astrophysics Data System (ADS)

    Wakasa, Masanobu; Sakaguchi, Yoshio; Hayashi, Hisaharu

    The inversion observed at 0·1 T for the magnetic field effects (MFEs) on the photoreduction of xanthone with p-aminothiophenol was investigated in the absence and the presence of a paramagnetic Gd3+ ion with the aid of a laser flash photolysis technique. The MFEs owing to the ?g and relaxation mechanisms were experimentally separated by the addition of Gd3+. Thus, we have proved for the present reaction that the MFEs owing to the hyperfine coupling mechanism and relaxation mechanism appear in a low field region (below 0·1 T) and that the MFEs owing to the ?g mechanism gradually appear in a high field region (above 0·1 T).

  18. Magnetism

    NSDL National Science Digital Library

    University Corporation for Atmospheric Research Windows to the Universe team

    2007-12-12

    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.

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

    NASA Technical Reports Server (NTRS)

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

    1976-01-01

    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.

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

    SciTech Connect

    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

    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.

  1. Coercivity enhancement driven by interfacial magnetic phase separation in SrTiO3(001)/Nd0.5Sr0.5CoO3

    SciTech Connect

    Sharma, M [University of Minnesota; Gazquez Alabart, Jaume [ORNL; Varela del Arco, Maria [ORNL; Schmitt, J. [University of Minnesota; Leighton, chris [University of Minnesota

    2011-01-01

    Thin-film perovskite cobaltites have been found to exhibit coercivity values enhanced by almost 2 orders of magnitude in comparison to bulk. In this paper, we have investigated this unexplained coercivity enhancement in detail, focusing on epitaxial SrTiO{sub 3}(001)/Nd{sub 0.5}Sr{sub 0.5}CoO{sub 3} [SrTiO{sub 3} = STO] films, which display coercivity values up to 40 kOe at low temperatures. Thickness-dependent (10-800 {angstrom}) magnetometry and magnetotransport studies demonstrate that nanoscopic magnetic phase separation occurs in the interface region of Nd{sub 0.5}Sr{sub 0.5}CoO{sub 3} [consistent with recent work on SrTiO{sub 3}(001)/La{sub 1-x}Sr{sub x}CoO{sub 3}], which is responsible for the degradation in magnetic and electronic properties in the very-thin-film limit. The coercivity is shown to be intimately related to the existence of this (70-{angstrom}-thick) interfacial phase-separated layer, leading us to advance an explanation for the coercivity enhancement in terms of the pinning of domain walls by interfacial nanoscopic ferromagnetic clusters and a crossover to single domain clusters at very low thickness. Simple estimates of the magnetocrystalline anisotropy (from the maximum coercivity), cluster dimensions (from the superparamagnetic blocking temperature), multidomain to single domain crossover point, and domain-wall width, provide quantitative support for this picture.

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

    SciTech Connect

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

    2005-05-01

    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.

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

    PubMed

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

    2015-05-15

    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, 2.5 g of Na2SO4, pH 1.7, 3.0 min of stir time, and 5.5 min centrifugation. The limits of detection were 0.07-0.53 ?g kg(-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

  4. Standardized peptidome profiling of human cerebrospinal fluid by magnetic bead separation and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry.

    PubMed

    Bruegel, Mathias; Planert, Mathis; Baumann, Sven; Focke, Almut; Bergh, Florian Then; Leichtle, Alexander; Ceglarek, Uta; Thiery, Joachim; Fiedler, Georg Martin

    2009-05-01

    Peptidome profiling of human cerebrospinal fluid (CSF) is a promising tool to identify novel disease-associated biomarkers. Our aim was to develop a standardized protocol for reproducible peptidome profiling of CSF using magnetic bead (MB) separation followed by MALDI-TOF MS. Peptidome fractionation and profiling of CSF were performed using MBs with different surface functionalities. We investigated exogenous variables (storage conditions, freeze-thaw-cycles) and endogenous interferences (albumin, immunoglobulin, blood, leukocytes) in pooled CSF samples. We detected approximately 500 signals with an S/N ratio >10 and an overlap frequency of about 40% in non-pathological CSF. Within- and between-day imprecisions in relative signal intensities ranged from 3 to 28% and 7 to 47%, respectively. CSF storage at room temperature for up to 6 h and at 4 degrees C for up to 3 days did not significantly influence the mass spectra. Consecutive freeze-thaw-cycles significantly affected the mass spectra. High albumin and immunoglobulin content altered the CSF preparation using MB-HIC C8 beads. Blood contamination showed no effect on mass spectra up to a hemoglobin concentration of 0.075 micromol/L. The presence of leukocytes up to a cell number of 30 Mpt/L did not affect mass spectra. Our reliable pretreatment protocol allows standardization of preanalytical modalities and thereby enables reproducible peptidome profiling of human CSF using MB separation followed by MALDI-TOF MS. PMID:19111955

  5. A method to separate conservative and magnetically-induced electric fields in calculations for MRI and MRS in electrically-small samples.

    PubMed

    Park, BuSik; Webb, Andrew G; Collins, Christopher M

    2009-08-01

    This work presents a method to separately analyze the conservative electric fields (E(c), primarily originating with the scalar electric potential in the coil winding), and the magnetically-induced electric fields (E(i), caused by the time-varying magnetic field B1) within samples that are much smaller than one wavelength at the frequency of interest. The method consists of first using a numerical simulation method to calculate the total electric field (E(t)) and conduction currents (J), then calculating E(i) based on J, and finally calculating E(c) by subtracting E(i) from E(t). The method was applied to calculate electric fields for a small cylindrical sample in a solenoid at 600MHz. When a non-conductive sample was modeled, calculated values of E(i) and E(c) were at least in rough agreement with very simple analytical approximations. When the sample was given dielectric and/or conductive properties, E(c) was seen to decrease, but still remained much larger than E(i). When a recently-published approach to reduce heating by placing a passive conductor in the shape of a slotted cylinder between the coil and sample was modeled, reduced E(c) and improved B1 homogeneity within the sample resulted, in agreement with the published results. PMID:19520593

  6. Rapid ionic liquid-based ultrasound assisted dual magnetic microextraction to preconcentrate and separate cadmium-4-(2-thiazolylazo)-resorcinol complex from environmental and biological samples.

    PubMed

    Khan, Sumaira; Kazi, Tasneem Gul; Soylak, Mustafa

    2014-04-01

    A rapid and innovative microextraction technique named as, ionic liquid-based ultrasound-assisted dual magnetic microextraction (IL-UA-DMME) was developed for the preconcentration and extraction of trace cadmium from environmental and biological samples, prior to analyzed by flame atomic absorption spectrometry (FAAS). The proposed method has many obvious advantages, including evading the use of organic solvents and achieved high extraction yields by the combination of dispersive liquid-liquid microextraction (DLLME) and magnetic mediated-solid phase extraction (MM-SPE). In this approach ionic liquid (IL) 1-butyl-3-methylimidazolium hexafluorophosphate [C4mim][PF6] play an important role to extract the cadmium-4-(2-thiazolylazo)-resorcinol (Cd-TAR) complex from acid digested sample solutions and ultrasonic irradiation was applied to assist emulsification. After then, dispersed small amount of Fe3O4 magnetic nanoparticles (MNPs) in sample solutions to salvaged the IL and complete phase separation was attained. Some analytical parameters that influencing the efficiency of proposed (IL-UA-DMME) method, such as pH, volume of IL, ligand concentration, ultra-sonication time, amount of Fe3O4 MNPs, sample volume and matrix effect were optimized. Limit of detection (LOD) and enrichment factor (EF) of the method under optimal experimental conditions were found to be 0.40?gL(-1) and 100, respectively. The relative standard deviation (RSD) of 50?gL(-1) Cd was 4.29%. The validity and accuracy of proposed method, was assessed to analyzed certified reference materials of fortified lake water TMDA-54.4, SPS-WW2 waste water, spinach leaves 1570a and also checked by standard addition method. The obtained values showed good agreement with the certified values and sufficiently high recovery were found in the range of 98.1-101% for Cd. The proposed method was facile, rapid and successfully applied for the determination of Cd in environmental and different biological samples. PMID:24398463

  7. Cryo-scanning electron microscopy (Cryo-SEM) of semen frozen in medium-straws from good and sub-standard freezer AI-boars.

    PubMed

    Hernández, Marta; Ekwall, Hans; Roca, Jordi; Vazquez, Juan Maria; Martinez, Emilio; Rodríguez-Martínez, Heriberto

    2007-02-01

    A major limiting factor for commercial cryopreservation of boar semen for artificial insemination (AI) is the large individual variation to cooling, where the degree of cell dehydration during ice (re)shaping seems to play a major role. This study investigated, in the frozen state, the degree of dehydration and ice crystal distribution in boar semen doses whose spermatozoa displayed different viability after thawing. Cross-sectioned medium-straws (0.5 mL, n=10) from a total of 10 stud boars classified as "good"(n=5) or sub-standard (e.g., "bad" freezers, n=5) by conventional analyses (computer assisted motility and sperm viability) were examined by Cryo-scanning electron microscopy (Cryo-SEM) to determine whether differences between groups could be already distinguishable prior to thawing. The degree of hydration was monitored in relation to the areas of ice crystal formed extracellularly (lakes), the areas of frozen, concentrated extender (veins) where spermatozoa were located and the degree of compartmentalization (number of lakes) present. Irrespectively of the region studied, the gradient of main dehydration (as lakes) observed along the cross-section area of the straws was very irregular. Most spermatozoa were enclosed in the freezing extender matrix and no obvious signs of external membrane damage were observed. None of the Cryo-SEM variables significantly correlated with post-thaw sperm parameters (p>0.05). However, we identified significant differences (p<0.0001) among boars for all ultrastructure variables studied, including the size of the veins, where differences in solute concentration is expected. We concluded that despite the large variability in ice crystal formation during the conventional freezing process among boars, this is unrelated to inter-boar post-thaw sperm differences. PMID:17222399

  8. Cryo-ablation improves anti-tumor immunity through recovering tumor educated dendritic cells in tumor-draining lymph nodes

    PubMed Central

    He, Xiao-Zheng; Wang, Qi-Fu; Han, Shuai; Wang, Hui-Qing; Ye, Yong-Yi; Zhu, Zhi-Yuan; Zhang, Shi-Zhong

    2015-01-01

    Background In addition to minimally invasive destruction of tumors, cryo-ablation of tumors to some extent modulated anti-tumor immunity. Cryo-ablated tumors in glioma mice models induced anti-tumor cellular immunologic response which increases the percentage of CD3+ and CD4+T cells in blood as well as natural killer cells. As a crucial role in triggering anti-tumor immunity, dendritic cells (DCs) were educated by tumors to adopt a tolerance phenotype which helps the tumor escape from immune monitoring. This study aims to study whether cryo-ablation could influence the tolerogenic DCs, and influence anti-tumor immunity in tumor-draining lymph nodes (TDLNs). Methods Using the GL261 subcutaneous glioma mouse model, we created a tumor bearing group, cryo-ablation group, and surgery group. We analyzed alteration in phenotype and function of tolerogenic DCs, and evaluated the factors of anti-tumor immunity inhibition. Results DCs in TDLNs in GL261 subcutaneous glioma mouse model expressed tolerogenic phenotype. In contrast to surgery, cryo-ablation improved the quantity and quality of these tolerogenic DCs. Moreover, the DCs decreased the expression of intracellular interleukin-10 (IL-10) and extra-cellular IL-10. In vitro, DCs from the cryo-ablation group recovered their specific function and induced potent anti-tumor immunity through triggering T cells. In vivo, cryo-ablation showed weak anti-tumor immunity, only inhibiting the growth of rechallenged tumors. But many IL-10-low DCs, rather than IL-10-high DCs, infiltrated the tumors. More importantly, Tregs inhibited the performance of these DCs; and depletion of Tregs greatly improved anti-tumor immunity in vivo. Conclusion Cryo-ablation could recover function of tumor induced tolerogenic DCs in vitro; and depletion of Tregs could improve this anti-tumor effect in vivo. The Tregs/CD4+T and Tregs/CD25+T cells in TDLNs inhibit DCs’ activity and function. PMID:25792805

  9. Magnetic state of the structural separated anion-deficient La{sub 0.70}Sr{sub 0.30}MnO{sub 2.85} manganite

    SciTech Connect

    Trukhanov, S. V., E-mail: truhanov@ifttp.bas-net.by; Trukhanov, A. V. [Scientific Practical Materials Research Centre of NAS of Belarus (Belarus); Vasiliev, A. N. [Moscow State University (Russian Federation); Balagurov, A. M. [Joint Institute for Nuclear Research (Russian Federation); Szymczak, H. [Institute of Physics, PAS (Poland)

    2011-11-15

    The results of neutron diffraction studies of the La{sub 0.70}Sr{sub 0.30}MnO{sub 2.85} compound and its behavior in an external magnetic field are stated. It is established that in the 4-300 K temperature range, two structural perovskite phases coexist in the sample, which differ in symmetry (groups R3-bar c and I4/mcm). The reason for the phase separation is the clustering of oxygen vacancies. The temperature (4-300 K) and field (0-140 kOe) dependences of the specific magnetic moment are measured. It is found that in zero external field, the magnetic state of La{sub 0.70}Sr{sub 0.30}MnO{sub 2.85} is a cluster spin glass, which is the result of frustration of Mn{sup 3+}-O-Mn{sup 3+} exchange interactions. An increase in external magnetic field up to 10 kOe leads to fragmentation of ferromagnetic clusters and then to an increase in the degree of polarization of local spins of manganese and the emergence of long-range ferromagnetic order. With increasing magnetic field up to 140 kOe, the magnetic ordering temperature reaches 160 K. The causes of the structural and magnetic phase separation of this composition and formation mechanism of its spin-glass magnetic state are analyzed.

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

    NASA Astrophysics Data System (ADS)

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

    2006-04-01

    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.

  11. Cross-linking cellulose nanofibrils for potential elastic cryo-structured gels

    NASA Astrophysics Data System (ADS)

    Syverud, Kristin; Kirsebom, Harald; Hajizadeh, Solmaz; Chinga-Carrasco, Gary

    2011-12-01

    Cellulose nanofibrils were produced from P. radiata kraft pulp fibers. The nanofibrillation was facilitated by applying 2,2,6,6-tetramethylpiperidinyl-1-oxyl-mediated oxidation as pretreatment. The oxidized nanofibrils were cross-linked with polyethyleneimine and poly N-isopropylacrylamide- co-allylamine- co-methylenebisacrylamide particles and were frozen to form cryo-structured gels. Samples of the gels were critical-point dried, and the corresponding structures were assessed with scanning electron microscopy. It appears that the aldehyde groups in the oxidized nanofibrils are suitable reaction sites for cross-linking. The cryo-structured materials were spongy, elastic, and thus capable of regaining their shape after a given pressure was released, indicating a successful cross-linking. These novel types of gels are considered potential candidates in biomedical and biotechnological applications.

  12. CRYO-ELECTRON MICROSCOPY DATA DENOISING BASED ON THE GENERALIZED DIGITIZED TOTAL VARIATION METHOD

    PubMed Central

    ZHANG, QIN; BAJAJ, CHANDRAJIT L.

    2010-01-01

    The energy functional used in digitalized total variation method is expanded to a general form and a generalized digitized total variation (GDTV) denoising method is obtained. We further expand this method from 2-dimensional (2D) image to 3-dimensional (3D) image processing field. Cryo-electron microscopy (cryo EM) and single particle reconstruction are becoming part of standard collection of structural techniques used for studying macromolecular assemblies. Howerver, the 3D data obtained suffers greatly from noise and degradation for the low dose electron radiation. Thus, image enhancement and noise reduction are theoretically necessary to improve the data for the subsequent segmentation and/or structure skeletonization. Although there are several methods to tackle this problem, we are pleased to find that GDTV method is very efficient and can achieve better performance. Comparative experiments are carried out to verify the enhancement achieved by the GDTV method. PMID:21643538

  13. 3D structure of eukaryotic flagella in a quiescent state revealed by cryo-electron tomography

    PubMed Central

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

    2005-01-01

    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

  14. Validation of Cryo-EM Structure of IP3R1 Channel

    PubMed Central

    Murray, Stephen C.; Flanagan, John; Popova, Olga B.; Chiu, Wah; Ludtke, Steven J.; Serysheva, Irina I.

    2013-01-01

    Summary About a decade ago, three electron cryomicroscopy (cryo-EM) single particle reconstructions of IP3R1 were reported at low resolution. Disturbingly, these structures bore little similarity to one another, even at the level of quaternary structure. Recently, we published an improved structure of IP3R1 at ~1 nm resolution. However, this structure did not bear any resemblance to any of the three previously published structures, leading to the question of why the new structure should be considered more reliable than the original three. Here we apply several methods, including class-average/map comparisons, tilt-pair validation, and use of multiple refinement software packages, to give strong evidence for the reliability of our recent structure. The map resolution and feature resolvability are assessed with the ‘gold standard’ criterion. This approach is generally applicable to assessing the validity of cryo-EM maps of other molecular machines. PMID:23707684

  15. Preservation of high resolution protein structure by cryo-electron microscopy of vitreous sections

    PubMed Central

    Sader, Kasim; Studer, Daniel; Zuber, Benoît; Gnaegi, Helmut; Trinick, John

    2009-01-01

    We have quantitated the degree of structural preservation in cryo-sections of a vitrified biological specimen. Previous studies have used sections of periodic specimens to assess the resolution present, but preservation before sectioning was not assessed and so the damage due particularly to cutting was not clear. In this study large single crystals of lysozyme were vitrified and from these X-ray diffraction patterns extending to better than 2.1 Å were obtained. The crystals were high pressure frozen in 30% dextran, and cryo-sectioned using a diamond knife. In the best case, preservation to a resolution of 7.9 Å was shown by electron diffraction, the first observation of sub-nanometre structural preservation in a vitreous section. PMID:19819624

  16. Noise models and cryo-EM drift correction with a direct-electron camera

    PubMed Central

    Shigematsu, H.; Sigworth, F. J.

    2013-01-01

    Blurring due to specimen-holder drift is a common occurrence in cryo-EM images. Cameras employing active-pixel sensors are capable of high frame rates such that a single low-dose exposure can be acquired as a series of frames. In this paper we consider the possibility of tracking and compensating for overall drift in typical single-particle specimens through the analysis of frame sequences. A problem that arises in tracking through cross-correlation of frames obtained with the DE-12 camera from Direct Electron LLC is the presence of “hot-pixel noise”. This random pattern of bright pixels is highly correlated among frames. We show how a model of this noise can be employed to greatly reduce its effects. A filter function is derived that optimizes the tracking of image shifts by cross-correlation, and we demonstrate the tracking of specimen drift in typical cryo-EM specimens. PMID:23748163

  17. Ionic liquids as floatation media for cryo-ultramicrotomy of soft polymeric materials.

    PubMed

    Kim, Paul; David, Emeric; Raboin, Louis; Ribbe, Alexander E; Russell, Thomas P; Hoagland, David A

    2013-12-01

    Ionic liquids (ILs) and their mixtures with low molecular solvents present ideal properties for use as flotation liquids in cryo-ultramicrotomy. With control of T g and ? by co-solvent addition, flat, ultra-thin sections are reliably floated onto transmission electron microscopy grids even at temperatures as low as -100°C. Even more, the liquids and their mixtures are stable in the microtome trough for several hours because of low vapor pressure and low solidification temperature. Compared to established flotation media for soft polymer systems, the time and skill needed for cryo-ultramicrotomy are significantly reduced. Although just a handful of ILs are discussed and a good general choice identified, if different liquid characteristics are needed for a particular sample, thousands of additional ILs will perform similarly, giving this new approach enormous flexibility. PMID:24124997

  18. 4.4 Å cryo-EM structure of an enveloped alphavirus Venezuelan equine encephalitis virus.

    PubMed

    Zhang, Rui; Hryc, Corey F; Cong, Yao; Liu, Xiangan; Jakana, Joanita; Gorchakov, Rodion; Baker, Matthew L; Weaver, Scott C; Chiu, Wah

    2011-09-14

    Venezuelan equine encephalitis virus (VEEV), a member of the membrane-containing Alphavirus genus, is a human and equine pathogen, and has been developed as a biological weapon. Using electron cryo-microscopy (cryo-EM), we determined the structure of an attenuated vaccine strain, TC-83, of VEEV to 4.4 Å resolution. Our density map clearly resolves regions (including E1, E2 transmembrane helices and cytoplasmic tails) that were missing in the crystal structures of domains of alphavirus subunits. These new features are implicated in the fusion, assembly and budding processes of alphaviruses. Furthermore, our map reveals the unexpected E3 protein, which is cleaved and generally thought to be absent in the mature VEEV. Our structural results suggest a mechanism for the initial stage of nucleocapsid core formation, and shed light on the virulence attenuation, host recognition and neutralizing activities of VEEV and other alphavirus pathogens. PMID:21829169

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

    PubMed

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

    2012-02-01

    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

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

    PubMed Central

    Russo, Christopher J.; Passmore, Lori A.

    2014-01-01

    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

  1. Fine structure of granal thylakoid membrane organization using cryo electron tomography

    Microsoft Academic Search

    Roman Kou?il; Gert T. Oostergetel; Egbert J. Boekema

    2011-01-01

    The architecture of grana membranes from spinach chloroplasts was studied by cryo electron tomography. Tomographic reconstructions of ice-embedded isolated grana stacks enabled to resolve features of photosystem II (PSII) in the native membrane and to assign the absolute orientation of individual membranes of granal thylakoid discs. Averaging of 3D sub-volumes containing PSII complexes provided a 3D structure of the PSII

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

    PubMed Central

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

    2012-01-01

    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

  3. Practical performance evaluation of a 10k × 10k CCD for electron cryo-microscopy

    PubMed Central

    Bammes, Benjamin E.; Rochat, Ryan H.; Jakana, Joanita; Chiu, Wah

    2011-01-01

    Electron cryo-microscopy (cryo-EM) images are commonly collected using either charge-coupled devices (CCD) or photographic film. Both film and the current generation of 16 megapixel (4k × 4k) CCD cameras have yielded high-resolution structures. Yet, despite the many advantages of CCD cameras, more than two times as many structures of biological macromolecules have been published in recent years using photographic film. The continued preference to film, especially for subnanometer-resolution structures, may be partially influenced by the finer sampling and larger effective specimen imaging area offered by film. Large format digital cameras may finally allow them to overtake film as the preferred detector for cryo-EM. We have evaluated a 111-megapixel (10k × 10k) CCD camera with a 9 ?m pixel size. The spectral signal-to-noise ratios of low dose images of carbon film indicate that this detector is capable of providing signal up to at least 2/5 Nyquist frequency potentially retrievable for 3-D reconstructions of biological specimens, resulting in more than double the effective specimen imaging area of existing 4k × 4k CCD cameras. We verified our estimates using frozen-hydrated ?15 bacteriophage as a biological test specimen with previously determined structure, yielding a ~7 Å resolution single particle reconstruction from only 80 CCD frames. Finally, we explored the limits of current CCD technology by comparing the performance of this detector to various CCD cameras used for recording data yielding subnanometer resolution cryo-EM structures submitted to the Electron Microscopy Data Bank (http://www.emdatabank.org/). PMID:21619932

  4. Cryo-Electron Microscopy Structure of a Yeast Mitochondrial Preprotein Translocase

    Microsoft Academic Search

    Kirstin Model; Chris Meisinger; Werner Kühlbrandt

    2008-01-01

    The translocase of the outer mitochondrial membrane (TOM) complex is the main entry gate for proteins imported into mitochondria. We determined the structure of the native, unstained ?550-kDa core–Tom20 complex from Saccharomycescerevisiae by cryo-electron microscopy at 18-Å resolution. The complex is triangular, measuring 145 Å on edge, and has near-3-fold symmetry. Its bulk is made up of three globular ?50-Å domains.

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

    NASA Astrophysics Data System (ADS)

    Liu, Yu; Ye, Jong Chul

    2006-08-01

    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.

  6. Design manufacture and test of a cryo-stable Offner relay using aluminum foam core optics

    Microsoft Academic Search

    Ryan S. McClelland

    2001-01-01

    Aluminum foam core optics have the desirable characteristics of being lightweight, cryo-stable, and low cost. The availability of high quality aluminum foam and a bare aluminum super-polishing process have allowed high performance foam core optics made entirely of aluminum to be produced. Mirrors with integral mounts were designed for minimum surface error induced by self-weight deflection, thermal gradients, and mounting

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

    SciTech Connect

    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

    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.

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

    PubMed Central

    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

    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

  9. Streptavidin crystals as nanostructured supports and image-calibration references for cryo-EM data collection

    PubMed Central

    Wang, Liguo; Ounjai, Puey; Sigworth, Fred J.

    2013-01-01

    For cryo-EM structural studies we seek to image membrane proteins as single particles embedded in proteoliposomes. One technical difficulty has been the low density of liposomes that can be trapped in the ~100 nm ice layer that spans holes in the perforated carbon support film of EM grids. Inspired by the use of two-dimensional (2D) streptavidin crystals as an affinity surface for biotinylated DNA (Crucifix et al., 2004), we propose to use the crystals to tether liposomes doped with biotinylated lipids. The 2D crystal image also serves as a calibration of the image formation process, providing an absolute conversion from electrostatic potentials in the specimen to the EM image intensity, and serving as a quality control of acquired cryo-EM images. We were able to grow streptavidin crystals covering more than 90% of the holes in an EM grid, and which remained stable even under negative stain. The liposome density in the resulting cryo-EM sample was uniform and high due to the high-affinity binding of biotin to streptavidin. Using computational methods, the 2D crystal background can be removed from images without noticeable effect on image properties. PMID:18707004

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

    PubMed

    Scheres, Sjors Hw

    2014-01-01

    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

  11. Structural analysis of vimentin and keratin intermediate filaments by cryo-electron tomography

    SciTech Connect

    Norlen, Lars [Medical Nobel Institute, Department of Cellular and Molecular Biology (CMB), Karolinska Institute, and Dermatology Clinic, Karolinska University Hospital, Stockholm (Sweden)]. E-mail: lars.norlen@ki.se; Masich, Sergej [Medical Nobel Institute, Department of Cellular and Molecular Biology (CMB), Karolinska Institute, and Dermatology Clinic, Karolinska University Hospital, Stockholm (Sweden); Goldie, Kenneth N. [Bio21 Molecular Science and Biotechnology Institute, University of Melbourne, Parkville, VIC 3010 (Australia); School of Biological Sciences, University of Auckland, Auckland 1020 (New Zealand); Hoenger, Andreas [University of Colorado at Boulder, Department of Molecular, Cellular and Developmental Biology, Boulder CO, 80309-0347 (United States)

    2007-06-10

    Intermediate filaments are a large and structurally diverse group of cellular filaments that are classified into five different groups. They are referred to as intermediate filaments (IFs) because they are intermediate in diameter between the two other cytoskeletal filament systems that is filamentous actin and microtubules. The basic building block of IFs is a predominantly {alpha}-helical rod with variable length globular N- and C-terminal domains. On the ultra-structural level there are two major differences between IFs and microtubules or actin filaments: IFs are non-polar, and they do not exhibit large globular domains. IF molecules associate via a coiled-coil interaction into dimers and higher oligomers. Structural investigations into the molecular building plan of IFs have been performed with a variety of biophysical and imaging methods such as negative staining and metal-shadowing electron microscopy (EM), mass determination by scanning transmission EM, X-ray crystallography on fragments of the IF stalk and low-angle X-ray scattering. The actual packing of IF dimers into a long filament varies between the different families. Typically the dimers form so called protofibrils that further assemble into a filament. Here we introduce new cryo-imaging methods for structural investigations of IFs in vitro and in vivo, i.e., cryo-electron microscopy and cryo-electron tomography, as well as associated techniques such as the preparation and handling of vitrified sections of cellular specimens.

  12. Construction and organization of a BSL-3 cryo-electron microscopy laboratory at UTMB.

    PubMed

    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

    2013-03-01

    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 200keV 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

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

    SciTech Connect

    Brown, Alan; Long, Fei; Nicholls, Robert A.; Toots, Jaan; Emsley, Paul; Murshudov, Garib, E-mail: garib@mrc-lmb.cam.ac.uk [MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge CB2 0QH (United Kingdom)

    2015-01-01

    A description is given of new tools to facilitate model building and refinement into electron cryo-microscopy reconstructions. 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.

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

    SciTech Connect

    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

    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.

  15. Evolutionary Bidirectional Expansion for the Tracing of Alpha Helices in Cryo-Electron Microscopy Reconstructions

    PubMed Central

    Rusu, Mirabela; Wriggers, Willy

    2011-01-01

    Cryo-electron microscopy (cryo-EM) enables the imaging of macromolecular complexes in near-native environments at resolutions that often permit the visualization of secondary structure elements. For example, alpha helices frequently show consistent patterns in volumetric maps, exhibiting rod-like structures of high density. Here, we introduce VolTrac (Volume Tracer) - a novel technique for the annotation of alpha-helical density in cryo-EM data sets. VolTrac combines a genetic algorithm and a bidirectional expansion with a tabu search strategy to trace helical regions. Our method takes advantage of the stochastic search by using a genetic algorithm to identify optimal placements for a short cylindrical template, avoiding exploration of already characterized tabu regions. These placements are then utilized as starting positions for the adaptive bidirectional expansion that characterizes the curvature and length of the helical region. The method reliably predicted helices with seven or more residues in experimental and simulated maps at intermediate (4–10 Å) resolution. The observed success rates, ranging from 70.6% to 100%, depended on the map resolution and validation parameters. For successful predictions, the helical axes were located within 2Å from known helical axes of atomic structures. PMID:22155667

  16. Arctic sea ice freeboard from CryoSat-2: Validation using data from the first IceBridge underflight

    NASA Astrophysics Data System (ADS)

    Connor, L. N.; Laxon, S. W.; McAdoo, D. C.; Ridout, A.; Cullen, R.; Farrell, S.; Francis, R.

    2011-12-01

    Exact determination of thickness changes in Arctic sea ice is a primary goal of ESA's CryoSat-2 mission. Since its launch on April 8, 2010, CryoSat has collected data to map sea ice thickness and thereby monitor climate-driven ice thickness change. On April 20, 2010 just 12 days after CryoSat's launch - during NASA's IceBridge Spring 2010 campaign, the NASA DC-8 conducted a spatially and temporally coincident survey along some 670 km of a CryoSat ground-track in the northernmost Arctic Ocean. The DC-8 survey was flown out and back along the CryoSat ground-track. The DC-8 collected two laser altimetry datasets: (1) Laser Vegetation Imaging Sensor (LVIS) data, and (2) scanning laser Airborne Topographic Mapper (ATM) data. IceBridge also collected a number of other important data types including digital photography of sea ice, snow thickness radar, Ku-band radar altimetry and gravimetry, which are coincident and nearly simultaneous with SAR-mode Synthetic aperture Interferometric Radar ALtimeter (SIRAL) data collected by CryoSat. LVIS data were collected on the outbound high-altitude (25,000 feet) flight leg while ATM data were collected on the return, low-altitude (1500 feet) flight leg. CryoSat's SIRAL altimeter data are used to retrieve freeboard, i.e., the height of the ice surface above that of the local sea surface (observed in leads). Freeboard can be used to estimate sea ice thickness by assuming the ice is in isostatic equilibrium. In this investigation we compare freeboard retrievals from CryoSat with freeboard estimates derived using IceBridge data. Corrections for snow thickness are applied using IceBridge radar data. Freeboards retrieved using (a) LVIS data and (b) ATM data, are compared with CryoSat freeboard estimates. These two comparisons taken together provide an important assessment of CryoSat's capabilities to precisely map freeboard and thickness change of Arctic sea ice.

  17. Rigorous Dyson equation and quasi-separable T-scattering operator technique for study of magnetic response from ordered and disordered non-magnetic particles' ensembles at electromagnetic wave multiple scattering

    NASA Astrophysics Data System (ADS)

    Barabanenkov, Yurii N.; Barabanenkov, Mikhail Y.

    2013-05-01

    An exact Dyson equation for averaged over electromagnetic crystal unit cell propagating total wave electric field is derived, with supposing the incident wave electric field to have the Floquet property. The mass operator related to periodic structure effective tensor dielectric permittivity is written as double Fourier transform from electric field Tscattering operator of the structure unit cell. The Lippmann-Swinger equation for the unit cell T-scattering operator, written in terms of the unit cell T-scattering operator in free space and the electric field lattice tensor Green function interaction part, is resolved by quasi-separable method. This recently presented quasi-separable approach to unit cell Tscattering operator enables one to consider unit cell containing several particles, with coupling between them directly inside the cell as well as through the structure via above lattice Green function interaction part. The obtained quasiseparable unit cell T-scattering operator is applied to study double diamagnetic-paramagnetic narrow peak in artificial periodical material with unit cell including the coupled plasmonic particles. Actually this magnetic phenomenon is appeared as combination result of space-group resonance between two small dielectric spheres and plasmonic resonance inside a single sphere. Studying the magnetic response of disordered media, we use Dyson self-consistent exact equation for ensemble averaged wave electric field inside dense discrete random media, with a random mass operator having been put under averaging sign. The random mass operator was written in terms of particles' correlations functions of all orders and particles' clusters' T-scattering operators. We discuss comparison between the unit cell T-scattering operator of periodic discrete structure and a cluster T-scattering operator of random discrete structure and consider the above double diamagnetic-paramagnetic peak also in random discrete structure of coupled small plasmonic dielectric spherical particles.

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

    PubMed Central

    2013-01-01

    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

  19. Rapid and Specific Enrichment of Culturable Gram Negative Bacteria Using Non-Lethal Copper-Free Click Chemistry Coupled with Magnetic Beads Separation

    PubMed Central

    Fugier, Emilie; Dumont, Audrey; Malleron, Annie; Poquet, Enora; Mas Pons, Jordi; Baron, Aurélie; Vauzeilles, Boris; Dukan, Sam

    2015-01-01

    Currently, identification of pathogenic bacteria present at very low concentration requires a preliminary culture-based enrichment step. Many research efforts focus on the possibility to shorten this pre-enrichment step which is needed to reach the minimal number of cells that allows efficient identification. Rapid microbiological controls are a real public health issue and are required in food processing, water quality assessment or clinical pathology. Thus, the development of new methods for faster detection and isolation of pathogenic culturable bacteria is necessary. Here we describe a specific enrichment technique for culturable Gram negative bacteria, based on non-lethal click chemistry and the use of magnetic beads that allows fast detection and isolation. The assimilation and incorporation of an analog of Kdo, an essential component of lipopolysaccharides, possessing a bio-orthogonal azido function (Kdo-N3), allow functionalization of almost all Gram negative bacteria at the membrane level. Detection can be realized through strain-promoted azide-cyclooctyne cycloaddition, an example of click chemistry, which interestingly does not affect bacterial growth. Using E. coli as an example of Gram negative bacterium, we demonstrate the excellent specificity of the technique to detect culturable E. coli among bacterial mixtures also containing either dead E. coli, or live B. subtilis (as a model of microorganism not containing Kdo). Finally, in order to specifically isolate and concentrate culturable E. coli cells, we performed separation using magnetic beads in combination with click chemistry. This work highlights the efficiency of our technique to rapidly enrich and concentrate culturable Gram negative bacteria among other microorganisms that do not possess Kdo within their cell envelope. PMID:26061695

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

    PubMed

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

    2013-01-01

    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

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

    NASA Astrophysics Data System (ADS)

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

    2013-09-01

    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.

  2. Immunochromatographic strip for rapid detection of Cronobacter in powdered infant formula in combination with silica-coated magnetic nanoparticles separation and 16S rRNA probe.

    PubMed

    Chen, Fei; Ming, Xing; Chen, XingXing; Gan, Min; Wang, BaoGui; Xu, Feng; Wei, Hua

    2014-11-15

    Here we developed a sensitive, specific, and rapid immunochromatographic strip test for the detection of Cronobacter. Silica-coated magnetic nanoparticles were used to separate nucleic acid from Cronobacter lysate and eliminate the interference of food matrices successfully. A couple of 5'-end labeled probes, which was complementary to the 16S ribosomal DNA of Cronobacter, was used to hybridize with the nucleic acid. The hybrid product, labeled with digoxigenin on one side and biotin on the other side, was directly submitted to the immunochromatographic strip test and the anti-digoxigenin monoclonal antibody was immobilized on nitrocellulose membrane in the test line. The visualization was achieved by gold nanoparticles conjugated to streptavidin, and double red bands appearing in both test and control line indicated a positive result of the presence of Cronobacter in testing sample. The detection limit was 10(7) cfu mL(-1) in pure culture. After silica-coated magnetic nanoparticles treatment, the detection limit was 10(5) and 10(6) cfu mL(-1) in pure culture and powdered infant formula, respectively, and maintained stable even under the interference of 10(8) cfu mL(-1)Salmonella typhimurium. Furthermore, 100 positive powdered infant formula samples spiked 10(8) cfu mL(-1)Cronobacter and 20 negative samples with none bacteria were tested by the strip, and the sensitivity and specificity of the test were both as high as 100%. This approach showed promise for microbial detection concerning food safety or clinical diagnosis. PMID:24907538

  3. Rapid and Specific Enrichment of Culturable Gram Negative Bacteria Using Non-Lethal Copper-Free Click Chemistry Coupled with Magnetic Beads Separation.

    PubMed

    Fugier, Emilie; Dumont, Audrey; Malleron, Annie; Poquet, Enora; Mas Pons, Jordi; Baron, Aurélie; Vauzeilles, Boris; Dukan, Sam

    2015-01-01

    Currently, identification of pathogenic bacteria present at very low concentration requires a preliminary culture-based enrichment step. Many research efforts focus on the possibility to shorten this pre-enrichment step which is needed to reach the minimal number of cells that allows efficient identification. Rapid microbiological controls are a real public health issue and are required in food processing, water quality assessment or clinical pathology. Thus, the development of new methods for faster detection and isolation of pathogenic culturable bacteria is necessary. Here we describe a specific enrichment technique for culturable Gram negative bacteria, based on non-lethal click chemistry and the use of magnetic beads that allows fast detection and isolation. The assimilation and incorporation of an analog of Kdo, an essential component of lipopolysaccharides, possessing a bio-orthogonal azido function (Kdo-N3), allow functionalization of almost all Gram negative bacteria at the membrane level. Detection can be realized through strain-promoted azide-cyclooctyne cycloaddition, an example of click chemistry, which interestingly does not affect bacterial growth. Using E. coli as an example of Gram negative bacterium, we demonstrate the excellent specificity of the technique to detect culturable E. coli among bacterial mixtures also containing either dead E. coli, or live B. subtilis (as a model of microorganism not containing Kdo). Finally, in order to specifically isolate and concentrate culturable E. coli cells, we performed separation using magnetic beads in combination with click chemistry. This work highlights the efficiency of our technique to rapidly enrich and concentrate culturable Gram negative bacteria among other microorganisms that do not possess Kdo within their cell envelope. PMID:26061695

  4. ESA-NASA collaboration in support of CryoSat-2

    NASA Astrophysics Data System (ADS)

    Casal, T. G.; Davidson, M.; Schuettemeyer, D.; Perrera, A.; Armitage, T.; Bianchi, R.; Parrinello, T.; Fornari, M.; Skourup, H.

    2012-12-01

    In the framework of its Earth Observation Programmes the European Space Agency (ESA) carries out groundbased and airborne campaigns to support geophysical algorithm development, calibration/validation, simulation of future spaceborne earth observation missions, and applications development related to land, oceans and atmosphere. ESA has been conducting airborne and ground measurements campaigns since 1981 by deploying a broad range of active and passive instrumentation in both the optical and microwave regions of the electromagnetic spectrum such as lidars, limb/nadir sounding interferometers/spectrometers, high-resolution spectral imagers, advanced synthetic aperture radars, altimeters and radiometers. These campaigns take place inside and outside Europe in collaboration with national research organisations in the ESA member states as well as with international organisations harmonising European campaign activities. For the different activities a rich variety of datasets has been recorded, are archived and users can access campaign data through the EOPI web portal [http://eopi.esa.int]. CryoSat-2, ESA's third Earth Explorer, is Europe's first mission dedicated to monitoring Earth's ice fields. The satellite carries a sophisticated radar altimeter that can measure the thickness of sea ice down to centimetres and also monitor changes in ice sheets, particularly around the edges where icebergs are calved from the vast ice sheets that cover Greenland and Antarctica. On order to gather data to help ensure the accuracy of ESA's ice mission, in yet another remarkable collaborative effort, ESA and NASA met up over the Arctic Ocean in April 2012 to perform some carefully coordinated flights directly under CryoSat orbiting above. The aim of this large-scale campaign was to record sea-ice thickness and conditions of the ice exactly along the line traced by ESA's CryoSat satellite orbiting high above. A range of sensors installed on the different aircraft was used to gather complementary information. These airborne instruments included simple cameras to get a visual record of the sea ice, laser scanners to clearly map the height of the ice, an ice-thickness sensor (EM-Bird), ESA's radar altimeter (ASIRAS) and NASA's snow and Ku-band radars, which mimic CryoSat's measurements but at a higher resolution. Preliminary results, obtained from the pooled flight time among teams of scientists from Europe, US and Canada, already show the capability to determine the amount of snow on the ice. Even more interestingly, from 700 km away, CryoSat is able to detect centimeter differences between sea-ice and thin ice/water, which in turn allow for the estimation of actual sea ice thickness at the time of the measurement.

  5. Remarkable magnetic relaxation and metamagnetic transition in phase-separated La0.7Ca0.3Mn0.9Cu0.1O3 perovskite

    NASA Astrophysics Data System (ADS)

    Gao, Tian; Cao, Shixun; Liu, Yongsheng; Zhou, Tao; Feng, Zhenjie; Zhang, Jincang

    2015-04-01

    The magnetic and electrical properties in phase-separated La0.7Ca0.3Mn0.9Cu0.1O3 perovskite were studied in detail. Experimental results show that the substitution of Cu at Mn-site suppresses the ferromagnetic (FM) phase of La0.7Ca0.3MnO3 matrix and induces a charge ordering transition at ˜146 K. At ˜256 K, a Griffiths-like behaviour is observed. At low temperatures, the occurrence of an irreversible metamagnetic transition associated with a large relaxation rate is analyzed, clearly indicating the dynamic phase coexistence and evolution of FM islands. A magnetic phase diagram is finally constructed based on the magnetic measurements, summarizing the dynamic evolution process of phase separation.

  6. Combining Envisat type and CryoSat-2 altimetry to inform hydrodynamic models

    NASA Astrophysics Data System (ADS)

    Schneider, Raphael; Nygaard Godiksen, Peter; Villadsen, Heidi; Madsen, Henrik; Bauer-Gottwein, Peter

    2015-04-01

    Hydrological models are developed and used for flood forecasting and water resources management. Such models rely on a variety of input and calibration data. In general, and especially in data scarce areas, remote sensing provides valuable data for the parameterization and updating of such models. Satellite radar altimeters provide water level measurements of inland water bodies. So far, many studies making use of satellite altimeters have been based on data from repeat-orbit missions such as Envisat, ERS or Jason or on synthetic wide-swath altimetry data as expected from the SWOT mission. This work represents one of the first hydrologic applications of altimetry data from a drifting orbit satellite mission, using data from CryoSat-2. We present an application where CryoSat-2 data is used to improve a hydrodynamic model of the Ganges and Brahmaputra river basins in South Asia set up in the DHI MIKE 11 software. The model's parameterization and forcing is mainly based on remote sensing data, for example the TRMM 3B42 precipitation product and the SRTM DEM for river and subcatchment delineation. CryoSat-2 water levels were extracted over a river mask derived from Landsat 7 and 8 imagery. After calibrating the hydrological-hydrodynamic model against observed discharge, simulated water levels were fitted to the CryoSat-2 data, with a focus on the Brahmaputra river in the Assam valley: The average simulated water level in the hydrodynamic model was fitted to the average water level along the river's course as observed by CryoSat-2 over the years 2011-2013 by adjusting the river bed elevation. In a second step, the cross section shapes were adjusted so that the simulated water level dynamics matched those obtained from Envisat virtual station time series. The discharge calibration resulted in Nash-Sutcliffe coefficients of 0.86 and 0.94 for the Ganges and Brahmaputra. Using the Landsat river mask, the CryoSat-2 water levels show consistency along the river and are in good accordance with other products, such as the SRTM DEM. The adjusted hydrodynamic model reproduced the average water level profile along the river channel with a higher accuracy than a model based on the SRTM DEM. Furthermore, the amplitudes as observed in Envisat virtual station time series could be reproduced fitting simple triangular cross section shapes. A hydrodynamic model prepared in such a way provides water levels at any point along the river and any point in time, which are consistent with the multi-mission altimetric dataset. This means it can for example be updated by assimilation of near real-time water level measurements from CryoSat-2 improving its flood forecasting capability.

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

    PubMed

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

    2012-01-01

    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

  8. 3D-printed biosensor with poly(dimethylsiloxane) reservoir for magnetic separation and quantum dots-based immunolabeling of metallothionein.

    PubMed

    Heger, Zbynek; Zitka, Jan; Cernei, Natalia; Krizkova, Sona; Sztalmachova, Marketa; Kopel, Pavel; Masarik, Michal; Hodek, Petr; Zitka, Ondrej; Adam, Vojtech; Kizek, Rene

    2015-06-01

    Currently, metallothioneins (MTs) are extensively investigated as the molecular biomarkers and the significant positive association of the MT amount was observed in tumorous versus healthy tissue of various types of malignant tumors, including head and neck cancer. Thus, we proposed a biosensor with fluorescence detection, comprising paramagnetic nanoparticles (nanomaghemite core with gold nanoparticles containing shell) for the magnetic separation of MT, based on affinity of its sulfhydryl groups toward gold. Biosensor was crafted from PDMS combined with technology of 3D printing and contained reservoir with volume of 50 ?L linked to input (sample/detection components and washing/immunobuffer) and output (waste). For the immunolabeling of immobilized MT anti-MT antibodies conjugated to CdTe quantum dots through synthetic heptapeptide were employed. After optimization of fundamental conditions of the immunolabeling (120 min, 20°C, and 1250 rpm) we performed it on a surface of paramagnetic nanoparticles in the biosensor reservoir, with evaluation of fluorescence of quantum dots (?exc 400 nm, and ?em 555 nm). The developed biosensor was applied for quantification of MT in cell lines derived from spinocellular carcinoma (cell line 122P-N) and fibroblasts (122P-F) and levels of the biomarker were found to be about 90 nM in tumor cells and 37 nM in fibroblasts. The proposed system is able to work with low volumes (< 100 ?L), with low acquisition costs and high portability. PMID:25735231

  9. Novel ion imprinted polymer magnetic mesoporous silica nano-particles for selective separation and determination of lead ions in food samples.

    PubMed

    Aboufazeli, Forouzan; Zhad, Hamid Reza Lotfi; Sadeghi, Omid; Karimi, Mohammad; Najafi, Ezzatollah

    2013-12-15

    A novel Pb(II) ion imprinted polymer coated on magnetic mesoporous silica was synthesised and characterised by scanning electron microscopy (SEM), thermal gravimetric/differential thermal analysis (TG/DTA), elemental analysis (CHN) and low angle X-ray powder diffraction (XRD). The application of this sorbent was investigated in preconcentration and determination of low concentrations of lead ions. Through this study, various effective factors on determination, such as pH of the sample solution, eluent including type, concentration and volume, adsorption and desorption time which are effective on the method efficiency, were appraised. In order to investigate the selectivity of this sorbent toward Pb(II) ions, the effect of variety of ions on preconcentration and recovery of Pb(II) ions were also investigated. The limit of detection (LOD) was found to be lower than 1.3 ?g L(-1) and the recovery and relative standard deviation (RSD%) of the method were higher than 97.3% and lower than 2.9%, respectively. The application of this sorbent was investigated in separation and determination of lead-contaminated food with concentration below the detection limit of flame atomic adsorption spectroscopy. Validation of the presented method was performed by analysing several standard reference materials with certified lead concentrations. PMID:23993507

  10. Magnetism

    NSDL National Science Digital Library

    David Stern

    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.

  11. Solenoidal Magnet Installation

    SciTech Connect

    Stredde, H.; Lee, A.; /Fermilab

    1998-01-21

    The major modification to the D0 detector for the next physics collider run is the upgrade of the central tracking system. The first component to be installed will be the solenoid magnet, with the central pre-shower attached. This engineering note is directed to the installation of the solenoid magnet and the equipment needed to accomplish this task. As part of the installation process, the main detector must undergo a change in position of one of its major components, namely the South End Calorimeter (SEC). This calorimeter must be completely decoupled from the main detector, i.e. all cabling and cryo lines removed. The equipment used for installing all calorimeters (bridge and support structures) will be put into position and the calorimeter (SEC) will be pulled off of the detector center beam and parked on the south sidewalk of the D0 Assembly Hall. The necessary cryo lines will re-connected in order to keep the cryostat cold. This calorimeter will remain here during the greater portion of the upgrade reconfiguration schedule. When this task is finished, the old central tracking system and its mounts will be removed from the bore of the Central Calorimeter (CC). The main detector is now ready to receive the new tracking system, starting with the solenoid magnet.

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

    NASA Technical Reports Server (NTRS)

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

    1998-01-01

    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.

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

    PubMed Central

    Gupta, Ramji; Gupta, Sarthak

    2015-01-01

    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. PMID:25657417

  14. Molecular Dynamics Flexible Fitting: A practical guide to combine cryo-electron microscopy and X-ray crystallography

    PubMed Central

    Trabuco, Leonardo G.; Villa, Elizabeth; Schreiner, Eduard; Harrison, Christopher B.; Schulten, Klaus

    2009-01-01

    Hybrid computational methods for combining structural data from different sources and resolutions are becoming an essential part of structural biology, especially as the field moves toward the study of large macromolecular assemblies. We have developed the molecular dynamics flexible fitting (MDFF) method for combining high-resolution atomic structures with cryo-electron microscopy (cryo-EM) maps, that results in atomic models representing the conformational state captured by cryo-EM. The method has been applied successfully to the ribosome, a ribonucleoprotein complex responsible for protein synthesis. MDFF involves a molecular dynamics simulation in which a guiding potential, based on the cryo-EM map, is added to the standard force field. Forces proportional to the gradient of the density map guide an atomic structure, available from X-ray crystallography, into high-density regions of a cryo-EM map. In this paper we describe the necessary steps to set up, run, and analyze MDFF simulations and the software packages that implement the corresponding functionalities. PMID:19398010

  15. 2.8 Å resolution reconstruction of the Thermoplasma acidophilum 20S proteasome using cryo-electron microscopy.

    PubMed

    Campbell, Melody G; Veesler, David; Cheng, Anchi; Potter, Clinton S; Carragher, Bridget

    2015-01-01

    Recent developments in detector hardware and image-processing software have revolutionized single particle cryo-electron microscopy (cryoEM) and led to a wave of near-atomic resolution (typically ?3.3 Å) reconstructions. Reaching resolutions higher than 3 Å is a prerequisite for structure-based drug design and for cryoEM to become widely interesting to pharmaceutical industries. We report here the structure of the 700 kDa Thermoplasma acidophilum 20S proteasome (T20S), determined at 2.8 Å resolution by single-particle cryoEM. The quality of the reconstruction enables identifying the rotameric conformation adopted by some amino-acid side chains (rotamers) and resolving ordered water molecules, in agreement with the expectations for crystal structures at similar resolutions. The results described in this manuscript demonstrate that single particle cryoEM is capable of competing with X-ray crystallography for determination of protein structures of suitable quality for rational drug design. PMID:25760083

  16. 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)

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

    2014-01-01

    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.

  17. 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

    Baker, Timothy S.

    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

  18. SubspaceEM: A fast maximum-a-posteriori algorithm for cryo-EM single particle reconstruction.

    PubMed

    Dvornek, Nicha C; Sigworth, Fred J; Tagare, Hemant D

    2015-05-01

    Single particle reconstruction methods based on the maximum-likelihood principle and the expectation-maximization (E-M) algorithm are popular because of their ability to produce high resolution structures. However, these algorithms are computationally very expensive, requiring a network of computational servers. To overcome this computational bottleneck, we propose a new mathematical framework for accelerating maximum-likelihood reconstructions. The speedup is by orders of magnitude and the proposed algorithm produces similar quality reconstructions compared to the standard maximum-likelihood formulation. Our approach uses subspace approximations of the cryo-electron microscopy (cryo-EM) data and projection images, greatly reducing the number of image transformations and comparisons that are computed. Experiments using simulated and actual cryo-EM data show that speedup in overall execution time compared to traditional maximum-likelihood reconstruction reaches factors of over 300. PMID:25839831

  19. Cryo X-ray microscope with flat sample geometry for correlative fluorescence and nanoscale tomographic imaging.

    PubMed

    Schneider, Gerd; Guttmann, Peter; Rehbein, Stefan; Werner, Stephan; Follath, Rolf

    2012-02-01

    X-ray imaging offers a new 3-D view into cells. With its ability to penetrate whole hydrated cells it is ideally suited for pairing fluorescence light microscopy and nanoscale X-ray tomography. In this paper, we describe the X-ray optical set-up and the design of the cryo full-field transmission X-ray microscope (TXM) at the electron storage ring BESSY II. Compared to previous TXM set-ups with zone plate condenser monochromator, the new X-ray optical layout employs an undulator source, a spherical grating monochromator and an elliptically shaped glass capillary mirror as condenser. This set-up improves the spectral resolution by an order of magnitude. Furthermore, the partially coherent object illumination improves the contrast transfer of the microscope compared to incoherent conditions. With the new TXM, cells grown on flat support grids can be tilted perpendicular to the optical axis without any geometrical restrictions by the previously required pinhole for the zone plate monochromator close to the sample plane. We also developed an incorporated fluorescence light microscope which permits to record fluorescence, bright field and DIC images of cryogenic cells inside the TXM. For TXM tomography, imaging with multi-keV X-rays is a straightforward approach to increase the depth of focus. Under these conditions phase contrast imaging is necessary. For soft X-rays with shrinking depth of focus towards 10nm spatial resolution, thin optical sections through a thick specimen might be obtained by deconvolution X-ray microscopy. As alternative 3-D X-ray imaging techniques, the confocal cryo-STXM and the dual beam cryo-FIB/STXM with photoelectron detection are proposed. PMID:22273540

  20. Spotiton: a prototype for an integrated inkjet dispense and vitrification system for cryo-TEM.

    PubMed

    Jain, Tilak; Sheehan, Patrick; Crum, John; Carragher, Bridget; Potter, Clinton S

    2012-07-01

    Over the last three decades, Cryo-TEM has developed into a powerful technique for high-resolution imaging of biological macromolecules in their native vitrified state. However, the method for vitrifying specimens onto EM grids is essentially unchanged - application of ?3 ?L sample to a grid, followed by blotting and rapid plunge freezing into liquid ethane. Several trials are often required to obtain suitable thin (few hundred nanometers or less) vitrified layers amenable for cryo-TEM imaging, which results in waste of precious sample and resources. While commercially available instruments provide some level of automation to control the vitrification process in an effort to increase quality and reproducibility, obtaining satisfactory vitrified specimens remains a bottleneck in the Cryo-TEM pipeline. We describe here a completely novel method for EM specimen preparation based on small volume (picoliter to nanoliter) dispensing using inkjet technology. A first prototype system (Spotiton v0.5) demonstrates feasibility of this new approach for specimen vitrification. A piezo-electric inkjet dispenser is integrated with optical real-time cameras (100 Hz frame rate) to analyze picoliter to nanoliter droplet profiles in-flight and spreading dynamics on the grid, and thus provides a method to optimize timing of the process. Using TEM imaging and biochemical assays we demonstrate that the piezo-electric inkjet mechanism does not disrupt the structural or functional integrity of macromolecules. These preliminary studies provide insight into the factors and components that will need further development to enable a robust and repeatable technique for specimen vitrification using this novel approach. PMID:22569522

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

    PubMed Central

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

    2013-01-01

    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

  2. Visualization of the Herpes Simplex Virus Portal in situ by Cryo-electron Tomography

    PubMed Central

    Cardone, Giovanni; Winkler, Dennis C.; Trus, Benes L.; Cheng, Naiqian; Heuser, John E.; Newcomb, William W.; Brown, Jay C.; Steven, Alasdair C.

    2007-01-01

    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 twelve 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 ~ 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 functional divergence at the level of portal-related functions other than its role as a DNA channel. PMID:17188319

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

    PubMed

    Apps, Peter; Mmualefe, Lesego

    2012-09-28

    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

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

    NASA Astrophysics Data System (ADS)

    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

    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.

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

    PubMed Central

    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

    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

  6. Southern hemisphere sand furrows: spatial patterning and implications for the cryo-venting process.

    NASA Astrophysics Data System (ADS)

    Nash, Ciaran; Bourke, Mary

    2015-04-01

    Carbon dioxide is an important volatile on Mars. Seasonally, atmospheric CO2 condenses as ice on to the Martian surface and sublimates during the spring. Links have been made between a suite of observed surface features and the sublimation of surface CO2 ice; these include spider-like araneiform, gullies, and fans. Sand furrows are one such feature; suggested to form due to the erosive action of pressurised CO2 gas as it escapes through cracks in surficial ice (i.e. cryo-venting, Bourke, 2013). There are significant and important differences between the North and South Hemispheres, particularly in the seasonal CO2 deposits. Previous investigations into the formation and distribution of sand furrows on Mars have concentrated solely on the northern hemisphere. We present a study of furrows in the southern hemisphere which has yielded new data on their distribution and spatial patterning as well as providing insights into the cryo-venting process. A total of 221 dune sites were surveyed over the three Martian years' of available HiRISE data to establish the overall distribution of sand furrows. A more detailed study was carried out at eight sites using data from Mars Year 30. These sites represent a latitudinal sample of dunefields located between 40°S to 72°S. Surficial CO2 ice thickness was estimated using the Mars Climate Database (Millour et al., 2014). Our data show that sand furrows are significantly less numerous in the study region than in the northern hemisphere where data show they occur in 95% of surveyed sites. We found a strong correlation between latitude and furrow distribution. As one progresses polewards from 40°S, furrows become more numerous until 68°S. Furrows were not detected south of 72°S. Carbon dioxide ice thickness has been highlighted as a potentially important factor controlling furrow distribution in the northern hemisphere (Bourke and McGaley-Towle, 2014). Results from our investigation suggest there is a feedback mechanism between CO¬2 ice thickness and furrow formation; indicating a threshold thickness above which geomorphologically effective cryo-venting may not occur. Bourke, M. C., The Formation of Sand Furrows by Cryo-Venting on Martian Dunes. 44th Lunar and Planetary Science Conference. Lunar and Planetary Institute, Houston, 2013, pp. Abstract #2919. Bourke, M. C., McGaley-Towle, Why do sand furrows distributions vary in the North Polar latitudes on Mars? , European Geosciences Union, Vienna, Vol. 16, EGU2014-13626, 2014. Millour, E., et al., The Mars Climate Database (MCD version 5.1). Eighth International Conference on Mars. Lunar and Planetary Institute, Houston, 2014, pp. Abstract #1184.

  7. Cryo Cooler Induced Micro-Vibration Disturbances to the Hubble Space Telescope

    NASA Technical Reports Server (NTRS)

    Jedrich, Nick; Zimbelman, Darrell; Turczyn, Mark; Sills, Joel; Voorhees, Carl; Clapp, Brian; Brumfield, Mark (Technical Monitor)

    2002-01-01

    This paper presents an overview of the Hubble Space Telescope (HST) Near Infrared Camera and Multi-Object Spectrometer (NICMOS) Cryo Cooler (MCC) system, a description of the micro-vibration characterization testing performed, and a discussion of the simulated performance. The NCC is a reverse Brayton cycle system that employs micro turbo-machinery to provide cooling to the NICMOS instrument. Extensive testing was conducted to quantify the expected on-orbit disturbances caused by the micro turbo-machinery and provide input to a flexible-body dynamic simulation to demonstrate compliance with the HST 7 milli-arcsecond root mean square jitter requirement.

  8. Cryo-banking of Prunus mume pollen and its application in cross-breeding.

    PubMed

    Zhang, Ya-Li; Chen, Rui-Dan; Huang, Cui-Juan; Liu, Yan

    2009-01-01

    The Mei (Prunus mume Sieb. et Zucc.) is one of the most widely used landscape plants and important germplasm resources in China. The study of pollen cryopreservation and the construction of a pollen cryo-bank have great importance in Mei research. From 2003 to 2007 we cryopreserved pollen from 51 Mei cultivars. In vitro germination of cryopreserved pollen was not significantly different from that of fresh pollen, even after four years of storage in liquid nitrogen. Cryopreserved pollen of 19 cultivars was used successfully for intraspecific hybridizations at Wuhan and Beijing in 2005 and 2006. PMID:19750240

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

    NASA Astrophysics Data System (ADS)

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

    2014-03-01

    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.

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

    NASA Astrophysics Data System (ADS)

    Lee, S.; Im, J.; Kim, J. W.; Kim, M.; Shin, M.

    2014-12-01

    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. Sea ice extent has constantly declined since 1980s. 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. 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 provided data to detect polar area elevation change between 2003 and 2009. CryoSat-2 launched with Synthetic Aperture Radar (SAR)/Interferometric Radar Altimeter (SIRAL) in April 2010 can provide data to estimate time-series of Arctic sea ice thickness. In this study, Arctic sea ice freeboard and thickness between 2011 and 2014 were estimated using CryoSat-2 SAR and SARIn mode data that have sea ice surface height relative to the reference ellipsoid WGS84. In order to estimate sea ice thickness, freeboard, i.e., elevation difference between the top of sea ice surface should be calculated. Freeboard can be estimated through detecting leads. We proposed a novel lead detection approach. CryoSat-2 profiles such as pulse peakiness, backscatter sigma-0, stack standard deviation, skewness and kurtosis were examined to distinguish leads from sea ice. Near-real time cloud-free MODIS images corresponding to CryoSat-2 data measured were used to visually identify leads. Rule-based machine learning approaches such as See5.0 and random forest were used to identify leads. The proposed lead detection approach better distinguished leads from sea ice than the existing approaches. With the freeboard height calculated using the lead detection approach, sea ice thickness was finally estimated using the Archimedes' buoyancy principle. The estimated sea ice freeboard and thickness were validated using ESA airborne Ku-band interferometric radar and Airborne Electromagnetic (AEM) data.

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

    NASA Astrophysics Data System (ADS)

    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

    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.

  12. Cryo-Vacuum Testing of the Integrated Science Instrument Module for the James Webb Space Telescope

    NASA Astrophysics Data System (ADS)

    Kimble, Randy A.; Davila, P. S.; Drury, M. P.; Glazer, S. D.; Krom, J. R.; Lundquist, R. A.; Mann, S. D.; McGuffey, D. B.; Perry, R. L.; Ramey, D. D.

    2012-01-01

    With delivery of the science instruments for the James Webb Space Telescope (JWST) to Goddard Space Flight Center (GSFC) expected in 2012, current plans call for the first cryo-vacuum test of the Integrated Science Instrument Module (ISIM) to be carried out at GSFC in early 2013. Plans are well underway for conducting this ambitious test, which will perform critical verifications of a number of optical, thermal, and operational requirements of the ISIM hardware, at its deep cryogenic operating temperature. We describe here the facilities, goals, methods, and timeline for this important Integration & Test milestone in the JWST program.

  13. CryoSat-2: Measuring fluctuations of land and marine ice fields from space

    NASA Astrophysics Data System (ADS)

    Francis, Richard; Wingham, Duncan; Cullen, Robert

    2010-05-01

    1. INTRODUCTION CryoSat was chosen as the first of ESA's Earth Explorer Opportunity missions in late 1999, following a competitive selection process [1]. Unfortunately, the CryoSat satellite was lost as the result of a launch failure on 8 October 2005. The decision was made to rebuild the satellite in order to complete the mission, and as a result of this the new satellite, CryoSat-2, will be launched on 25 February 2010. 2. MISSION OBJECTIVES The mission goal of CryoSat is the measurement of secular change in the cryosphere, particularly in the elevation of the ice caps and the thickness of sea ice [2]. The required accuracy corresponds to about half of the variation expected due to natural variability, over reasonable scales for the surfaces concerned. The selected technique is radar altimetry, although the instrument has been modified to provide the enhanced capabilities needed to significantly extend the spatial coverage of previous altimetry missions, particularly ERS and EnviSat. Thus the radar includes a synthetic aperture mode which enables the along- track resolution to be improved to about 250 m. This will enable detection of leads in sea-ice which are narrower than those detected hitherto, so that operation deeper into pack-ice can be achieved with a consequent reduction in errors due to omission. Altimetry over the steep edges of ice caps is hampered by the irregular topography which, since the radar ranging is performed to the closest reflector rather than the point directly below, introduces uncertainty into the exactitude of repeat measurements. CryoSat's radar includes a second antenna and receiver chain so that interferometry may be used to determine the arrival angle of the echo and so improve localisation of the reflection. The satellite payload, which includes a DORIS receiver for precise orbit determination and a set of star trackers to measure the orientation of the interferometer, is quite complex and demanding. 3. CRYOSAT-1 LAUNCH FAILURE AND THE MISSION RECOVERY WITH CRYOSAT-2 CryoSat was launched on 8 October 2005, just less than 6 years after the start of the programme. Unfortunately the launch vehicle, a Rockot launcher derived from the Russian SS-19 ICBM, suffered an anomaly at the end of its second-stage flight, with the result that the satellite was lost, the debris falling close to the North pole. Determination to rebuild the satellite and carry out the mission was extremely widespread: within 5 months all of the necessary funding issues, legal procedures, industrial commitments and resource demands had been solved and the programme restarted. The new satellite, inevitably called CryoSat-2, includes a large number of improvements compared to its predecessor, although many are internal changes to improve the reliability and ease of operations. More significantly, the expected lifetime has been increased. The satellite measurements will be supported by a comprehensive set of validation data, collected on the surface and from airborne platforms. These validation data, designed to specifically address the uncertainties in the interpretation of the radar echoes, have been collected during a series of carefully co-ordinated measurement campaigns over several years. Additionally, techniques to enable the collocation of surface and satellite measurements over the moving sea-ice have been developed and rehearsed, ready to support the dedicated validation campaigns during the mission. CryoSat-2 will be launched from Baikonur, Kazakhstan on 25 February 2010. Launch was originally planned for March 2009, again with a Rockot. But lack of availability of this vehicle (more specifically, the versatile third stage added to the ICBM) has induced a change to the Dnepr launcher, also an ICBM: the SS-18. So finally, about 11 years after it was first selected, the CryoSat mission will start collecting data. 4. REFERENCES [1] http://www.esa.int/livingplanet/cryosat [2] Wingham, D. J., Francis, C. R., Baker, S., Bouzinac, C., Cullen, R., de Chateau-Thierry, P., Laxon, S. W., Mallow, U., Mavrocordatos, C., Phalip

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

    PubMed

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

    2015-01-01

    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

  15. Cryo-electron microscopy study of bacteriophage T4 displaying anthrax toxin proteins

    SciTech Connect

    Fokine, Andrei; Bowman, Valorie D.; Battisti, Anthony J. [Department of Biological Sciences, Purdue University, 915 W. State Street, West Lafayette, IN 47907-2054 (United States); Li Qin [Department of Biology, Catholic University of America, 620 Michigan Avenue NE, Washington, DC 20064 (United States); Chipman, Paul R. [Department of Biological Sciences, Purdue University, 915 W. State Street, West Lafayette, IN 47907-2054 (United States); Rao, Venigalla B. [Department of Biology, Catholic University of America, 620 Michigan Avenue NE, Washington, DC 20064 (United States); Rossmann, Michael G. [Department of Biological Sciences, Purdue University, 915 W. State Street, West Lafayette, IN 47907-2054 (United States)], E-mail: mr@purdue.edu

    2007-10-25

    The bacteriophage T4 capsid contains two accessory surface proteins, the small outer capsid protein (Soc, 870 copies) and the highly antigenic outer capsid protein (Hoc, 155 copies). As these are dispensable for capsid formation, they can be used for displaying proteins and macromolecular complexes on the T4 capsid surface. Anthrax toxin components were attached to the T4 capsid as a fusion protein of the N-terminal domain of the anthrax lethal factor (LFn) with Soc. The LFn-Soc fusion protein was complexed in vitro with Hoc{sup -}Soc{sup -}T4 phage. Subsequently, cleaved anthrax protective antigen heptamers (PA63){sub 7} were attached to the exposed LFn domains. A cryo-electron microscopy study of the decorated T4 particles shows the complex of PA63 heptamers with LFn-Soc on the phage surface. Although the cryo-electron microscopy reconstruction is unable to differentiate on its own between different proposed models of the anthrax toxin, the density is consistent with a model that had predicted the orientation and position of three LFn molecules bound to one PA63 heptamer.

  16. Numerical Study of Cell Cryo-Preservation: A Network Model of Intracellular Ice Formation

    PubMed Central

    Li, Wei; Yang, Geer; Zhang, Aili; Xu, Lisa X.

    2013-01-01

    In this study, a new intracellular ice formation network model, coupled with an improved cell dehydration model has been developed. The non-uniform dehydration of the cell during freezing is simulated with moving boundary condition. Internal cell structures like cell nucleus are taken into consideration. The IIF network model is developed from classic diffusion limited IIF model in order to simulate spatial ice growth pattern inside cells. Simulation results suggest that cell nuclear plays a significant role in cryo-dehydration and would affect water/CPA concentration gradient inside the cell. At the same time, the ice growth pattern of exogenous IIF hypothesis is examined in the model. It is consistent with our previous experiments, in which we witnessed the intracellular ice first grown into the nucleus before spreading to the whole intercellular space. According to this model, the water concentration difference between nucleus and cytoplasm during cryo-dehydration could partly explain why ice crystal in the nucleus grows faster. However, it is not the dominate factor. Higher diffusion coefficient in cell nucleus might play a more important role in the phenomenon. PMID:23526979

  17. Backbone Model of an Aquareovirus Virion by Cryo-Electron Microscopy and Bioinformatics

    PubMed Central

    Cheng, Lingpeng; Zhu, Jiang; Hui, Wong Hoi; Zhang, Xiaokang; Honig, Barry; Fang, Qin; Zhou, Z. Hong

    2010-01-01

    Grass carp reovirus (GCRV) is a member of the aquareovirus genus in the Reoviridae family and has a capsid with two shells—a transcription-competent core surrounded by a coat. We report a near-atomic-resolution reconstruction of the GCRV virion by cryo-electron microscopy and single-particle reconstruction. A backbone model of the GCRV virion, including seven conformers of the five capsid proteins making up the 1500 molecules in both the core and the coat, was derived using cryo-electron microscopy density-map-constrained homology modeling and refinement. Our structure clearly showed that the amino-terminal segment of core protein VP3B forms an ~120-Å-long ?-helix-rich extension bridging across the icosahedral 2-fold-symmetry-related molecular interface. The presence of this unique structure across this interface and the lack of an external cementing molecule at this location in GCRV suggest a stabilizing role of this extended amino-terminal density. Moreover, part of this amino-terminal extension becomes invisible in the reconstruction of transcription-competent core particles, suggesting its involvement in endogenous viral RNA transcription. Our structure of the VP1 turret represents its open state, and comparison with its related structures at the closed state suggests hinge-like domain movements associated with the mRNA-capping machinery. Overall, this first backbone model of an aquareovirus virion provides a wealth of structural information for understanding the structural basis of GCRV assembly and transcription. PMID:20036256

  18. Flexible architecture of IP3R1 by Cryo-EM.

    PubMed

    Ludtke, Steven J; Tran, Thao P; Ngo, Que T; Moiseenkova-Bell, Vera Yu; Chiu, Wah; Serysheva, Irina I

    2011-08-10

    Inositol 1,4,5-trisphosphate receptors (IP3Rs) play a fundamental role in generating Ca2+ signals that trigger many cellular processes in virtually all eukaryotic cells. Thus far, the three-dimensional (3D) structure of these channels has remained extremely controversial. Here, we report a subnanometer resolution electron cryomicroscopy (cryo-EM) structure of a fully functional type 1 IP3R from cerebellum in the closed state. The transmembrane region reveals a twisted bundle of four ? helices, one from each subunit, that form a funnel shaped structure around the 4-fold symmetry axis, strikingly similar to the ion-conduction pore of K+ channels. The lumenal face of IP3R1 has prominent densities that surround the pore entrance and similar to the highly structured turrets of Kir channels. 3D statistical analysis of the cryo-EM density map identifies high variance in the cytoplasmic region. This structural variation could be attributed to genuine structural flexibility of IP3R1. PMID:21827954

  19. Flexible Architecture of IP3R1 by Cryo-EM

    PubMed Central

    Ludtke, Steven J.; Tran, Thao P.; Ngo, Que T.; Moiseenkova-Bell, Vera Yu.; Chiu, Wah; Serysheva, Irina I.

    2011-01-01

    SUMMARY Inositol 1,4,5-trisphosphate receptors (IP3Rs) play a fundamental role in generating Ca2+ signals that trigger many cellular processes in virtually all eukaryotic cells. So far, the three-dimensional (3D) structure of these channels has remained extremely controversial. Here, we report a subnanometer resolution electron cryomicroscopy (cryo-EM) structure of a fully functional type 1 IP3R from cerebellum in the closed state. The transmembrane region reveals a twisted bundle of four ?-helices, one from each subunit, that form a funnel shaped structure around the 4-fold symmetry axis, strikingly similar to the ion-conduction pore of K+ channels. The lumenal face of IP3R1 has prominent densities that surround the pore entrance and similar to the highly structured turrets of Kir channels. 3D statistical analysis of the cryo-EM density map identifies high variance in the cytoplasmic region. This structural variation could be attributed to genuine structural flexibility of IP3R1. PMID:21827954

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

    PubMed Central

    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

    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

  1. An approach to automated acquisition of cryoEM images from lacey carbon grids

    PubMed Central

    Nicholson, William V.; White, Howard; Trinick, John

    2010-01-01

    An approach to automated acquisition of cryoEM image data from lacey carbon grids using the Leginon program is described. Automated liquid nitrogen top up of the specimen holder dewar was used as a step towards full automation, without operator intervention during the course of data collection. During cryoEM studies of actin labelled with myosin V, we have found it necessary to work with lacey grids rather than Quantifoil or C-flat grids due to interaction of myosin V with the support film. Lacey grids have irregular holes of variable shape and size, in contrast to Quantifoil or C-flat grids which have a regular array of similar circular holes on each grid square. Other laboratories also prefer to work with grids with irregular holes for a variety of reasons. Therefore, it was necessary to develop a different strategy from normal Leginon usage for working with lacey grids for targetting holes for image acquisition and suitable areas for focussing prior to image acquisition. This approach was implemented by using the extensible framework provided by Leginon and by developing a new MSI application within that framework which includes a new Leginon node (for a novel method for finding focus targets). PMID:20817100

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

    PubMed Central

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

    2015-01-01

    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

  3. User requirements for the snow and land ice services - CryoLand

    NASA Astrophysics Data System (ADS)

    Malnes, E.; Buanes, A.; Nagler, T.; Bippus, G.; Gustafsson, D.; Schiller, C.; Metsämäki, S.; Pulliainen, J.; Luojus, K.; Larsen, H. E.; Solberg, R.; Diamandi, A.; Wiesmann, A.

    2015-06-01

    CryoLand (2011-2015) is a project carried out within the 7th Framework of the European Commission aimed at developing downstream services for monitoring seasonal snow, glaciers and lake/river ice primarily based on satellite remote sensing. The services target private and public users from a wide variety of application areas, and aim to develop sustainable services after the project is completed. The project has performed a thorough user requirement survey in order to derive targeted requirements for the service and provide recommendations for the design and priorities of the service. In this paper we describe the methods used, the major findings in this user survey, and how we used the results to design and specify the CryoLand snow and land ice service. The user requirement analysis shows that a European operational snow and land ice service is required and that there exists developed cryosphere products that can meet the specific needs. The majority of the users were mainly interested not only in the snow services, but also the lake/river ice products and the glacier products were desired.

  4. Structural changes in collagen fibrils across a mineralized interface revealed by cryo-TEM.

    PubMed

    Quan, Bryan D; Sone, Eli D

    2015-08-01

    The structure of the mineralized collagen fibril, which is the basic building block of mineralized connective tissues, is critical to its function. We use cryo-TEM to study collagen structure at a well-defined hard-soft tissue interface, across which collagen fibrils are continuous, in order to evaluate changes to collagen upon mineralization. To establish a basis for the analysis of collagen banding, we compared cryo-TEM images of rat-tail tendon collagen to a model based on the X-ray structure. While there is close correspondence of periodicity, differences in band intensity indicate fibril regions with high density but lacking order, providing new insight into collagen fibrillar structure. Across a mineralized interface, we show that mineralization results in an axial contraction of the fibril, concomitant with lateral expansion, and that this contraction occurs only in the more flexible gap region of the fibril. Nevertheless, the major features of the banding pattern are not significantly changed, indicating that the axial arrangement of molecules remains largely intact. These results suggest a mechanism by which collagen fibrils are able to accommodate large amounts of mineral without significant disruption of their molecular packing, leading to synergy of mechanical properties. PMID:25892483

  5. User requirements for the snow and land ice services - CryoLand

    NASA Astrophysics Data System (ADS)

    Malnes, E.; Buanes, A.; Nagler, T.; Bippus, G.; Gustafsson, D.; Schiller, C.; Metsämäki, S.; Pulliainen, J.; Luojus, K.; Larsen, H. E.; Solberg, R.; Diamandi, A.; Wiesmann, A.

    2015-02-01

    CryoLand (2011-2015) is a project carried out within the 7th Framework of the European Commission aimed at developing downstream services for monitoring seasonal snow, glaciers and lake/river ice primarily based on satellite remote sensing. The services target private and public users from a wide variety of application areas, and aim to develop sustainable services after the project is completed. The project has performed a thorough user requirement survey in order to derive targeted requirements for the service and provide recommendation for the design and priorities of the service. In this paper we describe the methods used, the major findings in this user survey, and how we used the results to design and specify the CryoLand snow and land ice service. The user requirement analysis shows that a European operational snow and land ice service is required and that there exists developed cryosphere products that can meet the specific needs. The majority of the users were mainly interested in the snow services, but also the lake/river ice products and the glacier products were desired.

  6. Variability of Arctic sea ice thickness and volume from CryoSat-2.

    PubMed

    Kwok, R; Cunningham, G F

    2015-07-13

    We present our estimates of the thickness and volume of the Arctic Ocean ice cover from CryoSat-2 data acquired between October 2010 and May 2014. Average ice thickness and draft differences are within 0.16?m of measurements from other sources (moorings, submarine, electromagnetic sensors, IceBridge). The choice of parameters that affect the conversion of ice freeboard to thickness is discussed. Estimates between 2011 and 2013 suggest moderate decreases in volume followed by a notable increase of more than 2500?km(3) (or 0.34?m of thickness over the basin) in 2014, which could be attributed to not only a cooler summer in 2013 but also to large-scale ice convergence just west of the Canadian Arctic Archipelago due to wind-driven onshore drift. Variability of volume and thickness in the multiyear ice zone underscores the importance of dynamics in maintaining the thickness of the Arctic ice cover. Volume estimates are compared with those from ICESat as well as the trends in ice thickness derived from submarine ice draft between 1980 and 2004. The combined ICESat and CryoSat-2 record yields reduced trends in volume loss compared with the 5?year ICESat record, which was weighted by the record-setting ice extent after the summer of 2007. PMID:26032317

  7. Cryo-electron tomography reveals ciliary defects underlying human RSPH1 primary ciliary dyskinesia

    PubMed Central

    Lin, Jianfeng; Yin, Weining; Smith, Maria C.; Song, Kangkang; Leigh, Margaret W.; Zariwala, Maimoona A.; Knowles, Michael R.; Ostrowski, Lawrence E.; Nicastro, Daniela

    2014-01-01

    Cilia play essential roles in normal human development and health; cilia dysfunction results in diseases such as primary ciliary dyskinesia (PCD). Despite their importance, the native structure of human cilia is unknown, and structural defects in the cilia of patients are often undetectable or remain elusive because of heterogeneity. Here, we develop an approach that enables visualization of human (patient) cilia at high-resolution using cryo-electron tomography of samples obtained non-invasively by nasal-scrape biopsy. We present the native 3D structures of normal and PCD-causing RSPH1-mutant human respiratory cilia in unprecedented detail; this allows comparisons of cilia structure across evolutionarily distant species and reveals the previously unknown primary defect and the heterogeneous secondary defects in RSPH1-mutant cilia. Our data provide evidence for structural and functional heterogeneity in radial spokes, suggest a mechanism for the milder RSPH1-PCD-phenotype, and demonstrate that cryo-electron tomography can be applied to human disease by directly imaging patient samples. PMID:25473808

  8. Cryo-FIB-nanotomography for quantitative analysis of particle structures in cement suspensions.

    PubMed

    Holzer, L; Gasser, P H; Kaech, A; Wegmann, M; Zingg, A; Wepf, R; Muench, B

    2007-09-01

    Cryo-FIB-nanotomography is a novel high-resolution 3D-microscopy technique, which opens new possibilities for the quantitative microstructural analysis of complex suspensions. In this paper, we describe the microstructural changes associated with dissolution and precipitation processes occurring in a fresh cement paste, which has high alumina and sulphate contents. During the first 6 min, precipitation of ettringite leads to a general decrease of the particle size distribution. In the unhydrated cement paste almost no particles smaller than 500 nm are present, whereas after 6 min this size class already represents 9 vol%. The precipitation of ettringite also leads to a significant increase of the particle number density from 0.294*10(9)/mm(3) at t(0min) to 20.55*10(9)/mm(3) at t(6min). Correspondingly the surface area increases from 0.75 m(2)/g at t(0min) to 2.13 m(2)/g at t(6min). The small ettringite particles tend to form agglomerates, which strongly influence the rheological properties. The particular strength of cryo-FIB-nt is the potential to quantify particle structures in suspension and thereby also to describe higher-order topological features such as the particle-particle interfaces, which is important for the study of agglomeration processes. PMID:17760616

  9. CryoSat Plus for Oceans - analysis of the state-of-the-art

    NASA Astrophysics Data System (ADS)

    Naeije, Marc; Gommenginger, Christine; Moreau, Thomas; Cotton, David; Benveniste, Jerome; Dinardo Dinardo, Salvatore

    2013-04-01

    The CryoSat Plus for Oceans (CP4O) project is an ESA initiative carried out by a European wide consortium of altimetry experts. It aims to build a sound scientific basis for new scientific and operational applications of data coming from CryoSat-2 over the open ocean, polar ocean, coastal seas and for seafloor mapping. It also generates and evaluates new methods and products that will enable the full exploitation of the capabilities of the CryoSat-2 SIRAL altimeter, and extend their application beyond the initial mission objectives. It therefore also acts as a preparation for the upcoming Sentinel and Jason SAR enabled altimetry missions. In this paper we address the review of the CryoSat state-of-the-art, relevant current initiatives, algorithms, models and Earth Observation based products and datasets that are relevant in the Cryosat+ ocean theme. Compared to conventional (pulse-limited) altimeter missions, Cryosat-2 is not a dedicated platform for ocean research: typically the microwave radiometer (MWR) for wet tropospheric corrections is lacking, as is the direct measurement of the first order ionospheric effect by means of a dual-frequency altimeter. Also the orbit of Cryosat-2 has a rather long repetition period, unsuited for collinear tracks analyses. These three particular features have been studied already in the HERACLES project on the eve of the first CryoSat launch. We revisit the outcome of this study, update to current understanding and perception, and ultimately develop what was, is and will be proposed in these problem areas. Clearly, we question the standard ionosphere corrections, the wet troposphere corrections and the accuracy of the mean sea surface (MSS) underlying the accuracy of derived sea level anomalies. In addition, Cryosat-2 provides the first innovative altimeter with SAR and SARIn modes. This raises the direct problem of "how to process these data", simply because this has not been done before. Compared to pulse-limited altimetry it is a totally different branch of sport. In our CP4O project we try to answer this. We build on the results that have come out of the SAMOSA study, which was initiated to investigate the improvements that SAR mode altimetry can offer in measurements over ocean, coastal and inland water surfaces, developing practical implementation of new theoretical models for the SAR echo waveform. It is clear that having specific processing for SAR and SARIn raises a number of new issues to be studied, such as RDSAR (reducing SAR to pseudo LRM data), sea state bias (SSB) in SAR mode, and land contamination, to name a few. The outcome of the analysis of the state-of-the-art culminates in the delivery of the Preliminary Analysis Report and the Development and Validation Plan (DVP). We present the summary of these documents.

  10. Surface molecular imprinting onto fluorescein-coated magnetic nanoparticles via reversible addition fragmentation chain transfer polymerization: a facile three-in-one system for recognition and separation of endocrine disrupting chemicals.

    PubMed

    Li, Ying; Dong, Cunku; Chu, Jia; Qi, Jingyao; Li, Xin

    2011-01-01

    In this study, we present a general protocol for the making of surface-imprinted magnetic fluorescence beads via reversible addition-fragmentation chain transfer polymerization. The resulting composites were characterized by X-ray diffraction analysis, transmission electron microscopy, scanning electron microscopy, fluorescence spectroscopy, Fourier transform infrared spectroscopy, and energy dispersive spectroscopy. The as-synthesized beads exhibited homogeneous polymer films (thickness of about 5.7 nm), spherical shape, high fluorescence intensity and magnetic property (Magnetization (Ms)=3.67 emu g(-1)). The hybrids bind the original template 17?-estradiol with an appreciable selectivity over structurally related compounds. In addition, the resulting hybrids performed without obvious deterioration after five repeated cycles. This study therefore demonstrates the potential of molecularly imprinted polymers for the recognition and separation of endocrine disrupting chemicals. PMID:21063623

  11. Comparative study on histological structures of the vitelline membrane of hen and duck egg observed by cryo-scanning electron microscopy.

    PubMed

    Chung, Wen-Hsin; Lai, Kung-Ming; Hsu, Kuo-chiang

    2010-02-10

    The histological structures of the vitelline membranes (VM) of hen and duck eggs were observed by cryo-scanning electron microscopy (cryo-SEM), and the chemical characteristics were also compared. The outer layer surface (OLS) of duck egg VM showed networks constructed by fibrils and sheets (0.1-5.2 microm in width), and that of hen egg presented networks formed only by sheets (2-6 microm in width). Thicker fibrils (0.5-1.5 microm in width) with different arrangement were observed on the inner layer surface (ILS) of duck egg VM as compared to those (0.3-0.7 microm in width) of hen egg VM. Upon separation, the outer surface of the outer layer (OSOL) and the inner surface of the inner layer (ISIL) of hen and duck egg VMs were quite similar to fresh VM except that the OSOL of duck egg VM showed networks constructed only by sheets. Thin fibrils interlaced above a bumpy or flat structure were observed at the exposed surface of the outer layer (ESOL) of hen and duck egg VMs. The exposed surfaces of inner layers (ESIL) of hen and duck egg VMs showed similar structures of fibrils, which joined, branched, and ran in straight lines for long distances up to 30 microm; however, the widths of the fibrils shown in ESOL and ESIL of duck egg VM were 0.1 and 0.7-1.4 microm, respectively, and were greater than those (<0.1 and 0.5-0.8 microm) of hen egg VM. The continuous membranes of both hen and duck egg VMs were still attached to the outer layers when separated. The content of protein, the major component of VM, was higher in duck egg VM (88.6%) than in hen egg VM (81.6%). Four and six major SDS-soluble protein patterns with distinct localization were observed in hen and duck egg VMs, respectively. Overall, the different histological structures of hen and duck egg VMs were suggested to be majorly attributable to the diverse protein components. PMID:20055415

  12. Surface molecular imprinting onto fluorescein-coated magnetic nanoparticles via reversible addition fragmentation chain transfer polymerization: A facile three-in-one system for recognition and separation of endocrine disrupting chemicals

    NASA Astrophysics Data System (ADS)

    Li, Ying; Dong, Cunku; Chu, Jia; Qi, Jingyao; Li, Xin

    2011-01-01

    In this study, we present a general protocol for the making of surface-imprinted magnetic fluorescence beads via reversible addition-fragmentation chain transfer polymerization. The resulting composites were characterized by X-ray diffraction analysis, transmission electron microscopy, scanning electron microscopy, fluorescence spectroscopy, Fourier transform infrared spectroscopy, and energy dispersive spectroscopy. The as-synthesized beads exhibited homogeneous polymer films (thickness of about 5.7 nm), spherical shape, high fluorescence intensity and magnetic property (Magnetization (Ms) = 3.67 emu g-1). The hybrids bind the original template 17?-estradiol with an appreciable selectivity over structurally related compounds. In addition, the resulting hybrids performed without obvious deterioration after five repeated cycles. This study therefore demonstrates the potential of molecularly imprinted polymers for the recognition and separation of endocrine disrupting chemicals.In this study, we present a general protocol for the making of surface-imprinted magnetic fluorescence beads via reversible addition-fragmentation chain transfer polymerization. The resulting composites were characterized by X-ray diffraction analysis, transmission electron microscopy, scanning electron microscopy, fluorescence spectroscopy, Fourier transform infrared spectroscopy, and energy dispersive spectroscopy. The as-synthesized beads exhibited homogeneous polymer films (thickness of about 5.7 nm), spherical shape, high fluorescence intensity and magnetic property (Magnetization (Ms) = 3.67 emu g-1). The hybrids bind the original template 17?-estradiol with an appreciable selectivity over structurally related compounds. In addition, the resulting hybrids performed without obvious deterioration after five repeated cycles. This study therefore demonstrates the potential of molecularly imprinted polymers for the recognition and separation of endocrine disrupting chemicals. Electronic supplementary information (ESI) available: Supplementary figure S1. The hysteresis loop of Fe3O4 (a), Fe3O4@SiO2 (b), and Fe3O4@SiO2-Dye-SiO2 (c). See DOI: 10.1039/c0nr00614a

  13. In Vivo Transplantation of Autogenous Marrow-Derived Cells Following Rapid Intraoperative Magnetic Separation Based on Hyaluronan to Augment Bone Regeneration

    PubMed Central

    Joshi, Powrnima; Fleury, Sean; Luangphakdy, Viviane; Shinohara, Kentaro; Pan, Hui; Boehm, Cynthia; Vasanji, Amit; Hefferan, Theresa E.; Walker, Esteban; Yaszemski, Michael; Hascall, Vincent; Zborowski, Maciej

    2013-01-01

    Introduction This project was designed to test the hypothesis that rapid intraoperative processing of bone marrow based on hyaluronan (HA) could be used to improve the outcome of local bone regeneration if the concentration and prevalence of marrow-derived connective tissue progenitors (CTPs) could be increased and nonprogenitors depleted before implantation. Methods HA was used as a marker for positive selection of marrow-derived CTPs using magnetic separation (MS) to obtain a population of HA-positive cells with an increased CTP prevalence. Mineralized cancellous allograft (MCA) was used as an osteoconductive carrier scaffold for loading of HA-positive cells. The canine femoral multidefect model was used and four cylindrical defects measuring 10?mm in diameter and 15?mm in length were grafted with MCA combined with unprocessed marrow or with MS processed marrow that was enriched in HA+ CTPs and depleted in red blood cells and nonprogenitors. Outcome was assessed at 4 weeks using quantitative 3D microcomputed tomography (micro-CT) analysis of bone formation and histomorphological assessment. Results Histomorphological assessment showed a significant increase in new bone formation and in the vascular sinus area in the MS-processed defects. Robust bone formation was found throughout the defect area in both groups (defects grafted with unprocessed marrow or with MS processed marrow.) Percent bone volume in the defects, as assessed by micro-CT, was greater in defects engrafted with MS processed cells, but the difference was not statistically significant. Conclusion Rapid intraoperative MS processing to enrich CTPs based on HA as a surface marker can be used to increase the concentration and prevalence of CTPs. MCA grafts supplemented with heparinized bone marrow or MS processed cells resulted in a robust and advanced stage of bone regeneration at 4 weeks. A greater new bone formation and vascular sinus area was found in defects grafted with MS processed cells. These data suggest that MS processing may be used to enhance the performance of marrow-derived CTPs in clinical bone regeneration procedures. Further assessment in a more stringent bone defect model is proposed. PMID:23082937

  14. Battery separators

    SciTech Connect

    Clegg, G.A.; Pearson, E.J.

    1981-01-13

    A description is given of a synthetic pulp separator for a lead acid battery, the separator having two or more plies and a ribbed profile the surface adapted to face the positive having a higher content of synthetic pulp than the other surface.

  15. Advantages and safety features using foundation fieldbus-H1 based instrumentation & control for cryo system in accelerators

    Microsoft Academic Search

    S Kaushik; K K M Haneef; M N Jayaram; D K Lalsare

    2008-01-01

    Large accelerator programme instrumentation and control for monitoring of large no. of parameters for cryogenic\\/cooling system. The parameters are Cryo Temperature, Vacuum, He Level and He flow etc. The circumference of the accelerator may vary up to several kilometers. Large size accelerators require huge cabling and hardware. The use of foundation fieldbus based Transmitters for measurement and Control valves field

  16. A Temperature-Stable Cryo-System for High-Temperature Superconducting MR In-Vivo Imaging

    PubMed Central

    Lin, In-Tsang; Yang, Hong-Chang; Chen, Jyh-Horng

    2013-01-01

    To perform a rat experiment using a high-temperature superconducting (HTS) surface resonator, a cryostat is essential to maintain the rat's temperature. In this work, a compact temperature-stable HTS cryo-system, keeping animal rectal temperature at 37.4°C for more than 3 hours, was successfully developed. With this HTS cryo-system, a 40-mm-diameter Bi2Sr2Ca2Cu3Ox (Bi-2223) surface resonator at 77 K was demonstrated in a 3-Tesla MRI system. The proton resonant frequency (PRF) method was employed to monitor the rat's temperature. Moreover, the capacity of MR thermometry in the HTS experiments was evaluated by correlating with data from independent fiber-optic sensor temperature measurements. The PRF thermal coefficient was derived as 0.03 rad/°C and the temperature-monitoring architecture can be implemented to upgrade the quality and safety in HTS experiments. The signal-to-noise ratio (SNR) of the HTS surface resonator at 77 K was higher than that of a professionally made copper surface resonator at 300 K, which has the same geometry, by a 3.79-fold SNR gain. Furthermore, the temperature-stable HTS cryo-system we developed can obtain stable SNR gain in every scan. A temperature-stable HTS cryo-system with an external air-blowing circulation system is demonstrated. PMID:23637936

  17. Fabrication of carbon films with ? 500nm holes for cryo-EM with a direct detector device.

    PubMed

    Marr, Chelsea R; Benlekbir, Samir; Rubinstein, John L

    2014-01-01

    Single particle electron cryomicroscopy (cryo-EM) is often performed using EM grids coated with a perforated or holey layer of amorphous carbon. Regular arrays of holes enable efficient cryo-EM data collection and several methods for the production of micropatterned holey-carbon film coated grids have been described. However, a new generation of direct detector device (DDD) electron microscope cameras can benefit from hole diameters that are smaller than currently available. Here we extend a previously proposed method involving soft lithography with a poly(dimethylsiloxane) (PDMS) stamp for the production of holey-carbon film coated EM grids. By incorporating electron-beam (e-beam) lithography and modifying the procedure, we are able to produce low-cost high-quality holey-carbon film coated EM grids with ?500nm holes spaced 4?m apart centre-to-centre. We demonstrate that these grids can be used for cryo-EM. Furthermore, we show that by applying image shifts to obtain movies of the carbon regions beside the holes after imaging the holes, the contrast transfer function (CTF) parameters needed for calculation of high-resolution cryo-EM maps with a DDD can be obtained efficiently. PMID:24269484

  18. A temperature-stable cryo-system for high-temperature superconducting MR in-vivo imaging.

    PubMed

    Lin, In-Tsang; Yang, Hong-Chang; Chen, Jyh-Horng

    2013-01-01

    To perform a rat experiment using a high-temperature superconducting (HTS) surface resonator, a cryostat is essential to maintain the rat's temperature. In this work, a compact temperature-stable HTS cryo-system, keeping animal rectal temperature at 37.4°C for more than 3 hours, was successfully developed. With this HTS cryo-system, a 40-mm-diameter Bi2Sr2Ca2Cu3Ox (Bi-2223) surface resonator at 77 K was demonstrated in a 3-Tesla MRI system. The proton resonant frequency (PRF) method was employed to monitor the rat's temperature. Moreover, the capacity of MR thermometry in the HTS experiments was evaluated by correlating with data from independent fiber-optic sensor temperature measurements. The PRF thermal coefficient was derived as 0.03 rad/°C and the temperature-monitoring architecture can be implemented to upgrade the quality and safety in HTS experiments. The signal-to-noise ratio (SNR) of the HTS surface resonator at 77 K was higher than that of a professionally made copper surface resonator at 300 K, which has the same geometry, by a 3.79-fold SNR gain. Furthermore, the temperature-stable HTS cryo-system we developed can obtain stable SNR gain in every scan. A temperature-stable HTS cryo-system with an external air-blowing circulation system is demonstrated. PMID:23637936

  19. Improved Oceanographic Measurements from SAR Altimetry: Results and Scientific Roadmap from the ESA CryoSat Plus For Oceans Project

    NASA Astrophysics Data System (ADS)

    Cotton, David; Andersen, Ole; Boy, Francois; Cancet, Mathilde; Dinardo, Salvatore; Gommenginger, Christine; Egido, Alejandro; Fernandes, Joana; Nilo Garcia, Pablo; Lucas, Bruno; Moreau, Thomas; Naeije, Marc; Scharroo, Remko; Stenseng, Lars; Benveniste, Jérôme

    2015-04-01

    The ESA CryoSat mission is the first space mission to carry a radar altimeter that can operate in Synthetic Aperture Radar (SAR) mode. It thus provides the first opportunity to test and evaluate, using real data, the significant potential benefits of SAR altimetry for ocean applications. The objective of the CryoSat Plus for Oceans (CP4O) project was to develop and evaluate new ocean products from CryoSat data and so maximize the scientific return of CryoSat over oceans. The main focus of CP4O has been on the additional measurement capabilities that are offered by the SAR mode of the SIRAL altimeter, with further work in developing improved geophysical corrections. CP4O has developed SAR based ocean products for application in four themes: Open Oceans, Coastal Oceans, Polar Oceans and Sea Floor Topography. The team has developed a number of new processing schemes and compared and evaluated the resultant data products. This work has clearly demonstrated the improved ocean measuring capability offered by SAR mode altimetry and has also added significantly to our understanding of the issues around the processing and interpretation of SAR altimeter echoes. The project finished in 2014, so this paper presents an overview of the major results and outlines a proposed roadmap for the further development and exploitation of these results in operational and scientific applications. The results are of course also highly relevant to support the planning for future missions, including Sentinel-3 and Jason-CS/Sentinel-6. The "CryoSat Plus for Oceans" (CP4O) project has been supported by ESA (Support To Science Element) and CNES.

  20. A Comparative Study of CG CryoDerm and AlloDerm in Direct-to-Implant Immediate Breast Reconstruction

    PubMed Central

    Park, Ki Rin; Kim, Tae Gon; Ha, Ju-Ho; Chung, Kyu-Jin; Kim, Yong-Ha; Lee, Soo Jung; Kang, Soo Hwan

    2013-01-01

    Background To date, various types of acellular dermal matrix (ADM) have been developed for clinical use. AlloDerm is the most familiar type of ADM to most surgeons in breast reconstruction. It is prepared by freeze-drying. CG CryoDerm is the first form of ADM that requires no drying process. Therefore, theoretically, it has a higher degree of preservation of the dermal structures than AlloDerm. We conducted this study to compare the clinical course and postoperative outcomes of patients who underwent direct-to-implant breast reconstructions using AlloDerm and those who did using CG CryoDerm. Methods We performed a retrospective analysis of the medical records in a consecutive series of 50 patients who underwent direct-to-implant breast reconstruction using AlloDerm (n=31) or CryoDerm (n=19). We then compared the clinical course and postoperative outcomes of the two groups based on the overall incidence of complications and the duration of drainage. Results The mean follow-up period was 16 months. There were no significant differences in the overall incidence of complications (seroma, infection, skin flap necrosis, capsular contracture, and implant loss) between the two groups. Nor was there any significant difference in the duration of drainage. Conclusions CG CryoDerm has the merits of short preparation time and easy handling during surgery. Our results indicate that CG CryoDerm might be an alternative allograft material to AlloDerm in direct-to-implant breast reconstruction. PMID:23898434

  1. In vitro assessment of a combined radiofrequency ablation and cryo-anchoring catheter for treatment of mitral valve prolapse.

    PubMed

    Boronyak, Steven M; Merryman, W David

    2014-03-21

    Percutaneous approaches to mitral valve repair are an attractive alternative to surgical repair or replacement. Radiofrequency ablation has the potential to approximate surgical leaflet resection by using resistive heating to reduce leaflet size, and cryogenic temperatures on a percutaneous catheter can potentially be used to reversibly adhere to moving mitral valve leaflets for reliable application of radiofrequency energy. We tested a combined cryo-anchoring and radiofrequency ablation catheter using excised porcine mitral valves placed in a left heart flow loop capable of reproducing physiologic pressure and flow waveforms. Transmitral flow and pressure were monitored during the cryo-anchoring procedure and compared to baseline flow conditions, and the extent of radiofrequency energy delivery to the mitral valve was assessed post-treatment. Long term durability of radiofrequency ablation treatment was assessed using statically treated leaflets placed in a stretch bioreactor for four weeks. Transmitral flow and pressure waveforms were largely unaltered during cryo-anchoring. Parameter fitting to mechanical data from leaflets treated with radiofrequency ablation and cryo-anchoring revealed significant mechanical differences from untreated leaflets, demonstrating successful ablation of mitral valves in a hemodynamic environment. Picrosirius red staining showed clear differences in morphology and collagen birefringence between treated and untreated leaflets. The durability study indicated that statically treated leaflets did not significantly change size or mechanics over four weeks. A cryo-anchoring and radiofrequency ablation catheter can adhere to and ablate mitral valve leaflets in a physiologic hemodynamic environment, providing a possible percutaneous alternative to surgical leaflet resection of mitral valve tissue. PMID:24495753

  2. A new challenge: in-situ investigation of the elusive nanostructures in wet halite and clay using BIB/FIB-cryo-SEM methods

    NASA Astrophysics Data System (ADS)

    Desbois, G.; Urai, J. L.

    2009-04-01

    Mudrocks and saltrocks form seals for hydrocarbon accumulations, aquitards and chemical barriers. The sealing capacity is controlled either by the rock microstructure or by chemical interactions between minerals and the permeating fluid. A detailed knowledge about the sealing characteristics is of particular interest in Petroleum Sciences. Other fields of interest are the storage of anthropogenic carbon dioxide and radioactive waste in geologic formations. A key factor to the understanding of sealing by mudstones and saltrocks is the study of their porosity. However, Halite and clay are so fluids sensitive that investigation on dried samples required by traditional methods of investigations (metal injection methods [6],[3]; magnetic susceptibility measurement [4]; SEM imaging of broken surfaces [5] and CT scanner computing [7]) are critical for robust interpretation. In one hand, none of these methods is able to directly describe the in-situ porosity at the pore scale and on the other hand, most of these methods require dried samples in which the natural structure of pores could be damaged due to the desiccation, dehydration and dissolution-recrystallisation of the fabric. SEM imaging is certainly the most direct approach to investigate the porosity but it is generally limited by the poor quality of the mechanically prepared surfaces. This problem is solved by the recent development of ion milling tools (FIB: Focussed Ion Beam or BIB: Broad Ion Beam, which allows producing in-situ high quality polished cross-sections suitable for high resolution pores SEM imaging at nano-scale. More over, new and innovative developments of the cryo-SEM approach in the Geosciences allow investigating samples under wet natural conditions. Thus, we are developing the combination of FIB/BIB-cryo-SEM methods ([1],[2]), which combine in one machine the vitrification of the pore fluids by very rapid cooling, the excavation of the sample by ion milling tool and SEM imaging. By these, we are able to stabilize the in-situ fluids in grain boundaries or pores, preserve the natural structures at nano scale, produce high quality polished cross-sections for high resolution SEM imaging and reconstruct accurately the grain boundary and the pore space networks in 3D by serial cross sectioning. Our first investigations on wet halite and wet clay materials produced unprecedented high quality images of fully preserved fluid-filled pore space as appear in nature. We have thus validated the use of the FIB/BIB-cryo-SEM technology for the in-situ investigations of the elusive structures in wet geomaterials paving the way towards a fuller understanding of how pore geometry can affect physical properties of rocks. [1] Desbois G. And Urai J.L. (submitted). In-situ morphology of meso-porosity in Boom clay (Mol site, Belgium) inferred by the innovative FIB-cryo-SEM method. E-earth. [2] Desbois G., Urai J.L., Burkhardt C., Drury M., Hayles M. and Humbel B. (2008). Cryogenic vitrification and 3D serial sectioning using high resolution cryo-FIB-SEM technology for brine-filled grain boundaries in halite: first results. Geofluids, 8: 60-72 [3] Esteban L., Géraud Y. And Bouchez J.L. (2006). Pore network geometry in low permeability argillites from magnetic fabric data and oriented mercury injections. Geophysical Research Letters, vol. 33, L18311, doi : 10.1029/2006GL026908. [4] Esteban L., Géraud Y. And Bouchez J.L. (2007). Pore network connectivity anisotropy in Jurassic argillite specimens from eastern Paris Basin (France). Physics and Chemistry of the Earth, 32(1) :161-169. [5] Hildenbrand A., Krooss B. M. and Urai J. L. (2005). Relationship between pore structure and fluid transport in argillaceous rocks. Solid Mechanics and Its Applications, IUTAM Symposium on Physicochemical and Electromechanical Interactions in Porous Media, 125 : 231-237, doi : 10.1007/1-4020-3865-8_26. [6] Hildenbrand A. and Urai J.L. (2003) Investigation of the morphology of pore space in mudstones—first results. Marine and Petroleum Geology, 20(10):1185-1200. [7] H. Taud H., Martinez-Angeles

  3. Cryo-electron microscopy of microstructures in self-assembled colloidal systems

    NASA Astrophysics Data System (ADS)

    Zheng, Yi

    Direct imaging transmission electron microscopy at cryogenic temperature (Cryo-TEM) is in many instances the most powerful probe of microstructures of self-assembled, i.e. equilibrium, colloidal systems. It is the only technique that allows model-independent, real-space imaging at high resolution. Continuing our group's two decades devoted research with Cryo-TEM, my thesis extends the technique to new territories. An on-the-grid deformation-and-relaxation sample preparation technique is developed that enables the time-resolved direct imaging of the recently discovered flow-induced vesicle-to-micelle transition in dilute aqueous surfactant solutions. The vesicles transform to an entangled network of thread-like micelles upon high straining rate; the process is reversible upon cessation of flow. Intermediate structures during the transition are captured by Cryo-TEM and correlated with rheological measurements. A mechanism of the transition is proposed which hinges on the alteration of electrical double layer structure by the flow-field, the alteration in turn shifting association balances between counterions and surfactant aggregates. Systematic study of a series of viscoelastic, drag-reducing micellar solutions of cationic surfactants reveals the significant effects of counterion-surfactant ratio and counterion chemical structure, correlates solution microstructures with rheological properties, and establishes the microstructural and rheological basis of drag-reduction in these solutions. Core-corona structures of poly(ethyleneoxide)/polybutadiene (PEO/PB) block copolymer micelles are directly resolved for the first time. Spherical micelles form at higher PEO/PB block volume ratio; cylindrical, at lower block volume ratio. Images of both shapes of micelles show a dense core and a diffuse corona. The core and corona sizes agree well with theoretical prediction from the "star" model of polymer micelles. Interesting mixed micelle structures are observed in aqueous solutions of binary mixtures of nonionic surfactants and nonionic amphiphilic block copolymers. The evolution of the micelle structure is studied in detail as the relative proportions of surfactant and copolymers are varied. The triblock copolymer behaves differently in forming mixed micelles than its diblock counterpart; the difference stems from the difference in block architecture.

  4. Airborne Grid Sea-Ice Surveys for Comparison with CryoSat-2

    NASA Astrophysics Data System (ADS)

    Brozena, J. M.; Gardner, J. M.; Liang, R.; Hagen, R. A.; Ball, D.

    2014-12-01

    The U.S. Naval Research Laboratory is engaged in a study of the changing Arctic with a particular focus on ice thickness and distribution variability. The purpose is to optimize computer models used to predict sea ice changes. An important part of our study is to calibrate/validate CryoSat-2 ice thickness data prior to its incorporation into new ice forecast models. The large footprint of the CryoSat-2 altimeter over sea-ice is a significant issue in any attempt to ground-truth the data. Along-track footprints are reduced to ~ 300 m by SAR processing of the returns. However, the cross-track footprint is determined by the topography of the surface. Further, the actual return is the sum of the returns from individual reflectors within the footprint making it difficult to interpret the return, and optimize the waveform tracker. We therefore collected a series of grids of airborne scanning lidar and nadir pointing radar on sub-satellite tracks over sea-ice that would extend far enough cross-track to capture the illuminated area. One difficulty in the collection of grids comprised of adjacent overlapping tracks is that the ice moves as much as 300 m over the duration of a single track (~ 10 min). With a typical lidar swath width of 500m we needed to adjust the survey tracks in near real-time for the ice motion. This was accomplished by a photogrammetric method of ice velocity determination (RTIME) reported in another presentation. Post-processing refinements resulted in typical track-to-track miss-ties of ~ 1-2 m, much of which could be attributed to ice deformation over the period of the survey. An important factor is that we were able to reconstruct the ice configuration at the time of the satellite overflight, resulting in an accurate representation of the surface illuminated by CryoSat-2. Our intention is to develop a model of the ice surface using the lidar grid which includes both snow and ice using radar profiles to determine snow thickness. In 2013 a set of 6 usable grids 5-20 km wide (cross-track) by 10-30 km long were collected north of Barrow, AK. In 2014 a further 5 narrower grids (~5km) were collected. Data from these grids are shown here and will be used to examine the relationship of the tracked satellite waveform data to the actual surface.

  5. Visualization of bacteriophage P1 infection by cryo-electron tomography of tiny Escherichia coli

    SciTech Connect

    Liu Jun, E-mail: Jun.Liu.1@uth.tmc.edu [Department of Pathology and Laboratory Medicine, University of Texas Medical School at Houston, Houston, TX 77030 (United States); Chen Chengyen [Department of Pathology and Laboratory Medicine, University of Texas Medical School at Houston, Houston, TX 77030 (United States); Shiomi, Daisuke; Niki, Hironori [Microbial Genetics Laboratory, Genetic Strain Research Center, National Institute of Genetics, Mishima, Shizuoka 411-8540 (Japan); Margolin, William, E-mail: William.Margolin@uth.tmc.edu [Department of Microbiology and Molecular Genetics, University of Texas Medical School at Houston, Houston, TX 77030 (United States)

    2011-09-01

    Bacteriophage P1 has a contractile tail that targets the conserved lipopolysaccharide on the outer membrane surface of the host for initial adsorption. The mechanism by which P1 DNA enters the host cell is not well understood, mainly because the transient molecular interactions between bacteriophage and bacteria have been difficult to study by conventional approaches. Here, we engineered tiny E. coli host cells so that the initial stages of P1-host interactions could be captured in unprecedented detail by cryo-electron tomography. Analysis of three-dimensional reconstructions of frozen-hydrated specimens revealed three predominant configurations: an extended tail stage with DNA present in the phage head, a contracted tail stage with DNA, and a contracted tail stage without DNA. Comparative analysis of various conformations indicated that there is uniform penetration of the inner tail tube into the E. coli periplasm and a significant movement of the baseplate away from the outer membrane during tail contraction.

  6. Semi-automated selection of cryo-EM particles in RELION-1.3.

    PubMed

    Scheres, Sjors H W

    2015-02-01

    The selection of particles suitable for high-resolution cryo-EM structure determination from noisy micrographs may represent a tedious and time-consuming step. Here, a semi-automated particle selection procedure is presented that has been implemented within the open-source software RELION. At the heart of the procedure lies a fully CTF-corrected template-based picking algorithm, which is supplemented by a fast sorting algorithm and reference-free 2D class averaging to remove false positives. With only limited user-interaction, the proposed procedure yields results that are comparable to manual particle selection. Together with an improved graphical user interface, these developments further contribute to turning RELION from a stand-alone refinement program into a convenient image processing pipeline for the entire single-particle approach. PMID:25486611

  7. Automated specimen search in cryo-TEM observation with DIFF-defocus imaging

    PubMed Central

    Nakamura, Natsuko; Shimizu, Yuko; Shinkawa, Takao; Nakata, Munetaka; Bammes, Benjamin; Zhang, Junjie; Chiu, Wah

    2010-01-01

    We have developed an automated specimen search algorithm for cryo-electron microscopy imaging of ice-embedded single particles suspended across regularly spaced holes. To maximize the particle visibility under a low electron exposure rate condition, specimen searching is carried out in diffraction mode. However, images in diffraction mode contain significant pincushion distortion, making it difficult to computationally predict the locations of the regularly spaced holes. We have implemented a distortion-correction mechanism to restore the primitive distortion-free image and a correlation-based algorithm to accurately determine the periodicity of the holes. A stage-shift method to optimize positional reproducibility is also implemented. Addition of our algorithms to the JADAS software for automated transmission electron microscopy data acquisition has significantly improved the accuracy of specimen search. PMID:20356853

  8. Atomic structure of human adenovirus by cryoEM reveals interactions among protein networks

    PubMed Central

    Liu, Hongrong; Jin, Lei; Koh, Sok Boon S.; Atanasov, Ivo; Schein, Stan; Wu, Lily; Zhou, Z Hong

    2012-01-01

    Construction of a complex virus may involve a hierarchy of assembly elements. Here, we report the structure of the whole human adenovirus virion at 3.6Å resolution by cryo-electron microscopy, revealing in situ atomic models of three minor capsid proteins (IIIa, VIII and IX), extensions of the major (penton base and hexon) capsid proteins, and interactions within three protein-protein networks. One network is mediated by protein IIIa within Group-of-Six (GOS) tiles – a penton base and its five surrounding hexons – at vertices. Another is mediated by ropes (protein IX) that lash hexons together to form Group-of-Nine (GON) tiles and bind GONs to GONs. The third, mediated by IIIa and VIII, binds each GOS to five surrounding GONs. Optimization of adenovirus for cancer and gene therapy could target these networks. PMID:20798312

  9. Pre-fusion structure of trimeric HIV-1 envelope glycoprotein determined by cryo-electron microscopy

    PubMed Central

    Bartesaghi, Alberto; Merk, Alan; Borgnia, Mario J.; Milne, Jacqueline L. S.; Subramaniam, Sriram

    2014-01-01

    The activation of trimeric HIV-1 envelope glycoprotein (Env) by its binding to the cell surface receptor CD4 and co-receptors (CCR5 or CXCR4) represents the first of a series of events that lead to fusion between viral and target cell membranes. Here, we present the cryo-electron microscopic structure, at ~ 6 Å resolution, of the closed, pre-fusion state of trimeric HIV-1 Env in complex with the broadly neutralizing antibody VRC03. We show that three gp41 helices at the core of the trimer serve as an anchor around which the rest of Env is reorganized upon activation to the open quaternary conformation. The architecture of trimeric HIV-1 Env in pre-fusion and activated intermediate states resembles the corresponding states of influenza hemagglutinin trimers, providing direct evidence for the similarity in entry mechanisms employed by HIV-1, influenza and related enveloped viruses. PMID:24154805

  10. Lessons learned from the flight of the NASA in-step cryo system experiment

    NASA Astrophysics Data System (ADS)

    Sugimura, Russell S.; Russo, Samuel C.; Gilman, David C.

    1996-03-01

    The Cryo System Experiment was developed to validate in near zero-g space a 65 K cryogenic system for focal planes, optics, or other imaging instruments that require continuous cryogenic cooling. Two key cryogenic technologies, designed to improve performance of systems for scientific, commercial and defense applications in space, were successfully demonstrated on NASA's recent shuttle mission, Discovery (STS 63), launched on February 3-11, 1995. The two advanced cryogenic technologies consisted of a 2-watt 65 K long-life low-vibration Stirling cooler, and a diode oxygen heat pipe thermal switch. Presented are highlights of the flight experiment and the effectiveness of lessons learned from the system integration of cryocooler and heat pipe technologies relating to: launch-vibration constraints for the expander cold-tips, a high-compliance thermal strap to minimize side loads on the expander, and the value of on-orbit diagnostics to check status of the cryocooler.

  11. Stack Characterization in CryoSat Level1b SAR/SARin Baseline C

    NASA Astrophysics Data System (ADS)

    Scagliola, Michele; Fornari, Marco; Di Giacinto, Andrea; Bouffard, Jerome; Féménias, Pierre; Parrinello, Tommaso

    2015-04-01

    CryoSat was launched on the 8th April 2010 and is the first European ice mission dedicated to the monitoring of precise changes in the thickness of polar ice sheets and floating sea ice. CryoSat is the first altimetry mission operating in SAR mode and it carries an innovative radar altimeter called the Synthetic Aperture Interferometric Altimeter (SIRAL), that transmits pulses at a high pulse repetition frequency thus making the received echoes phase coherent and suitable for azimuth processing. The current CryoSat IPF (Instrument Processing Facility), Baseline B, was released in operation in February 2012. After more than 2 years of development, the release in operations of the Baseline C is expected in the first half of 2015. It is worth recalling here that the CryoSat SAR/SARin IPF1 generates 20Hz waveforms in correspondence of an approximately equally spaced set of ground locations on the Earth surface, i.e. surface samples, and that a surface sample gathers a collection of single-look echoes coming from the processed bursts during the time of visibility. Thus, for a given surface sample, the stack can be defined as the collection of all the single-look echoes pointing to the current surface sample, after applying all the necessary range corrections. The L1B product contains the power average of all the single-look echoes in the stack: the multi-looked L1B waveform. This reduces the data volume, while removing some information contained in the single looks, useful for characterizing the surface and modelling the L1B waveform. To recover such information, a set of parameters has been added to the L1B product: the stack characterization or beam behaviour parameters. The stack characterization, already included in previous Baselines, has been reviewed and expanded in Baseline C. This poster describes all the stack characterization parameters, detailing what they represent and how they have been computed. In details, such parameters can be summarized in: - Stack statistical parameters, such as skewness and kurtosis - Look angle (i.e. the angle at which the surfaces sample is seen with respect to the nadir direction of the satellite) and Doppler angle (i.e. the angle at which the surfaces sample is seen with respect to the normal to the velocity vector) for the first and the last single-look echoes in the stack. - Number of single-looks averaged in the stack (in Baseline C a stack-weighting has been applied that reduces the number of looks). With the correct use of these parameters, users will be able to retrieve some of the 'lost' information contained within the stack and fully exploit the L1B product.

  12. Extraction of macro-molecule images in cryo-EM micrographs

    SciTech Connect

    Adiga, Umesha P.S.; Malladi, Ravi; Glaeser, Robert M.

    2003-03-20

    Advances in Electron Microscopy and single-particle reconstruction have led to results at increasingly high resolutions. This has opened up the possibility of complete automation of single particle reconstruction. Main bottleneck in automation of single particle reconstruction is manual selection of particles in the micrograph. This paper describes a simple but efficient approach for segmentation of particle projections in the micrographs obtained using cryo-electron microscope. Changing the shape of objects to facilitate segmentation from the cluster and reconstructing its actual shape after isolation is successfully attempted. Both low-level and high-level processing techniques are used and the whole process is made automatic. Over 90 percent success in automatic particle picking is achieved. Several areas for improvement and future research directions are discussed.

  13. Semi-automated selection of cryo-EM particles in RELION-1.3

    PubMed Central

    Scheres, Sjors H.W.

    2015-01-01

    The selection of particles suitable for high-resolution cryo-EM structure determination from noisy micrographs may represent a tedious and time-consuming step. Here, a semi-automated particle selection procedure is presented that has been implemented within the open-source software RELION. At the heart of the procedure lies a fully CTF-corrected template-based picking algorithm, which is supplemented by a fast sorting algorithm and reference-free 2D class averaging to remove false positives. With only limited user-interaction, the proposed procedure yields results that are comparable to manual particle selection. Together with an improved graphical user interface, these developments further contribute to turning RELION from a stand-alone refinement program into a convenient image processing pipeline for the entire single-particle approach. PMID:25486611

  14. Single-particle cryo-electron microscopy of Rift Valley fever virus

    SciTech Connect

    Sherman, Michael B. [Department of Biochemistry and Molecular Biology, University of Texas Medical Branch, Galveston, TX 77555 (United States); Sealy Center for Structural Biology and Molecular Biophysics, University of Texas Medical Branch, Galveston, TX 77555 (United States); Freiberg, Alexander N. [Department of Pathology, University of Texas Medical Branch, Galveston, TX 77555 (United States); Center for Biodefense and Emerging Infectious Diseases, University of Texas Medical Branch, Galveston, TX 77555 (United States); Holbrook, Michael R. [Department of Pathology, University of Texas Medical Branch, Galveston, TX 77555 (United States); Center for Biodefense and Emerging Infectious Diseases, University of Texas Medical Branch, Galveston, TX 77555 (United States); Institute for Human Infections and Immunity, University of Texas Medical Branch, Galveston, TX 77555 (United States); Watowich, Stanley J., E-mail: watowich@xray.utmb.ed [Department of Biochemistry and Molecular Biology, University of Texas Medical Branch, Galveston, TX 77555 (United States); Sealy Center for Structural Biology and Molecular Biophysics, University of Texas Medical Branch, Galveston, TX 77555 (United States); Center for Biodefense and Emerging Infectious Diseases, University of Texas Medical Branch, Galveston, TX 77555 (United States); Institute for Human Infections and Immunity, University of Texas Medical Branch, Galveston, TX 77555 (United States)

    2009-04-25

    Rift Valley fever virus (RVFV; Bunyaviridae; Phlebovirus) is an emerging human and veterinary pathogen causing acute hepatitis in ruminants and has the potential to cause hemorrhagic fever in humans. We report a three-dimensional reconstruction of RVFV vaccine strain MP-12 (RVFV MP-12) by cryo-electron microcopy using icosahedral symmetry of individual virions. Although the genomic core of RVFV MP-12 is apparently poorly ordered, the glycoproteins on the virus surface are highly symmetric and arranged on a T = 12 icosahedral lattice. Our RVFV MP-12 structure allowed clear identification of inter-capsomer contacts and definition of possible glycoprotein arrangements within capsomers. This structure provides a detailed model for phleboviruses, opens new avenues for high-resolution structural studies of the bunyavirus family, and aids the design of antiviral diagnostics and effective subunit vaccines.

  15. Cryo-Vacuum Testing of the JWST Integrated Science Instrument Module

    NASA Astrophysics Data System (ADS)

    Kimble, Randy A.; Antonille, Scott R.; Comber, Brian J.; Fatig, Curtis C.; Ferruit, Pierre; Glasse, Alistair; Glazer, Stuart D.; Kelly, Douglas M.; Lundquist, Ray; Mann, Steven D.; Martel, Andre; Novo-Gradac, Kevin J.; Ohl, Raymond George; Penanen, Konstantin; Shade, Edward L.; Sullivan, Joseph; Vila, Maria B.; Van Campen, Julie; Zak, Dean; Zhou, Julia

    2015-01-01

    In October of 2014, a major milestone in the JWST program was reached: completion of the first (of two planned) cryo-vacuum tests of the fully-assembled Integrated Science Instrument Module. This test, executed in the largest thermal-vacuum chamber of NASA's Goddard Space Flight Center, was a massive undertaking, with round-the-clock testing covering a period of 117 days from door-close to door-open. Over this period, the full complement of ISIM flight instruments, structure, harness radiator, and electronics were put through a comprehensive program of thermal, optical, electrical, and operational tests. In this paper, we briefly summarize the goals, setup, execution, and preliminary results of this important and very successful test.

  16. Spaceflight Engineering For The Remote Study Of The Terrestrial Cryosphere: The CryoEgg Platform

    NASA Astrophysics Data System (ADS)

    Bannister, N. P.; Wadham, J. L.; Ambrosi, R. M.; Bicknell, C. L.; Crawford, A.; Evans, M.; O'Brien, R. C.; Peters, G. M.; Ross, D.; Stapleton, P. E.; Stevenson, T.

    2007-12-01

    We describe a remote sensing platform for deployment at considerable depth within the cryosphere, targeted particularly at glacial and polar ice environments. The design exploits our team's heritage in space instrumentation and engineering to meet the requirements of autonomous operation under conditions of extreme pressure and temperature, in a compact and rugged package. The modular design permits reconfiguration of the device to meet the specific demands and scientific requirements of each deployment site. The platform is a core element of the CryoEgg programme, the aims of which are to produce an autonomous sensor system capable of monitoring basic chemical/biological and physical variables over the full spectrum of conditions in subglacial environments, and we describe the performance of the platform in verification tests and preliminary field trials at the Engabreen glacial laboratory in Norway.

  17. Identifying conformational states of macromolecules by eigen-analysis of resampled cryo-EM images.

    PubMed

    Penczek, Pawel A; Kimmel, Marek; Spahn, Christian M T

    2011-11-01

    We present the codimensional principal component analysis (PCA), a novel and straightforward method for resolving sample heterogeneity within a set of cryo-EM 2D projection images of macromolecular assemblies. The method employs PCA of resampled 3D structures computed using subsets of 2D data obtained with a novel hypergeometric sampling scheme. PCA provides us with a small subset of dominating "eigenvolumes" of the system, whose reprojections are compared with experimental projection data to yield their factorial coordinates constructed in a common framework of the 3D space of the macromolecule. Codimensional PCA is unique in the dramatic reduction of dimensionality of the problem, which facilitates rapid determination of both the plausible number of conformers in the sample and their 3D structures. We applied the codimensional PCA to a complex data set of Thermus thermophilus 70S ribosome, and we identified four major conformational states and visualized high mobility of the stalk base region. PMID:22078558

  18. Cryo-EM structure of a fully glycosylated soluble cleaved HIV-1 Env trimer

    PubMed Central

    Lyumkis, Dmitry; Julien, Jean-Philippe; de Val, Natalia; Cupo, Albert; Potter, Clinton S.; Klasse, Per Johan; Burton, Dennis R.; Sanders, Rogier W.; Moore, John P.; Carragher, Bridget; Wilson, Ian A.; Ward, Andrew B.

    2014-01-01

    The HIV-1 envelope glycoprotein (Env) trimer contains the receptor binding sites and membrane fusion machinery that introduce the viral genome into the host cell. As the only target for broadly neutralizing antibodies (bnAbs), Env is a focus for rational vaccine design. We present a cryo-electron microscopy reconstruction and structural model of a cleaved, soluble SOSIP gp140 trimer in complex with a CD4 binding site (CD4bs) bnAb, PGV04, at 5.8 Å resolution. The structure reveals the spatial arrangement of Env components, including the V1/V2, V3, HR1 and HR2 domains, and shielding glycans. The structure also provides insights into trimer assembly, gp120-gp41 interactions, and the CD4bs epitope cluster for bnAbs, which covers a more extensive area and defines a more complex site of vulnerability than previously described. PMID:24179160

  19. Zernike Phase Contrast Electron Cryo-Tomography Applied to Marine Cyanobacteria Infected with Cyanophages

    PubMed Central

    Dai, Wei; Fu, Caroline; Khant, Htet A.; Ludtke, Steven J.; Schmid, Michael F.; Chiu, Wah

    2015-01-01

    Advances in electron cryo-tomography have provided a new opportunity to visualize the internal 3D structures of a bacterium. An electron microscope equipped with Zernike phase contrast optics produces images with dramatically increased contrast compared to images obtained by conventional electron microscopy. Here we describe a protocol to apply Zernike phase plate technology for acquiring electron tomographic tilt series of cyanophage-infected cyanobacterial cells embedded in ice, without staining or chemical fixation. We detail the procedures for aligning and assessing phase plates for data collection, and methods to obtain 3D structures of cyanophage assembly intermediates in the host, by subtomogram alignment, classification and averaging. Acquiring three to four tomographic tilt series takes approximately 12 h on a JEM2200FS electron microscope. We expect this time requirement to decrease substantially as the technique matures. Time required for annotation and subtomogram averaging varies widely depending on the project goals and data volume. PMID:25321408

  20. An Australian contribution to CryoSat-II cal/val in East Antarctica including the Totten glacier region

    NASA Astrophysics Data System (ADS)

    Watson, C. S.; Burgette, R. J.; Tregoning, P.; Coleman, R.; Roberts, J.; Lieser, J. L.; Fricker, H. A.; Legresy, B.

    2010-12-01

    The Australian TOT-Cal project seeks to provide a contribution to the calibration and validation of the CryoSat-II mission over two adjacent important regions in East Antarctica. The first focuses on the Totten glacier, arguably one of the most important outlet glaciers in the East Antarctic, known to be undergoing significant surface lowering. The second includes the coastal slope regions behind Casey station and up on the plateau areas near Law Dome where significant spatial variation in annual accumulation is known to occur. The 2010/11 austral summer is the first field season for this project, with fieldwork to be underway at the time of the AGU FM10. In this poster, we present our current field activities and forward plans for the 2011/12 season. Our field campaign includes three components. A total of six in-situ GPS sites will be deployed over the summer period throughout the Law Dome / Totten Glacier region. These sites will facilitate the computation of the integrated water vapour content of the atmosphere, enabling an assessment against the ECMWF product used in the CyroSat-II data stream. The GPS sites also serve to provide reference stations for the AWI Polar-5 aircraft that will fly over the study area equipped with a scanning LiDAR and the ESA ASIRAS instrument. Finally, a series of kinematic GPS transects, corner cube reflector placements and surface density measurements will be undertaken from our field camp on the western flank of Law Dome to provide high resolution ground measurements for cal/val activities. In a separate project, Antarctic sea ice freeboard measurements will also contribute to the calibration and validation efforts by the Australian Antarctic program. In November 2010, the first set of such measurements will be carried out in the East Antarctic sea ice zone between 77 and 90 degrees East. The primary measurement tools for this campaign will include helicopter mounted scanning LiDAR and aerial photography, combined with in-situ sea ice observations. Over the next few austral spring seasons, similar measurements will be carried out, especially during a major marine cryosphere experiment on board the Australian RSV Aurora Australis in 2012.

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

    SciTech Connect

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

    2010-03-03

    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 determined for liquid hydrogen refueling with a single-flow nozzle and a pump that delivers 1.5 kg/min of liquid H{sub 2} to the insulated cryogenic tank capable of being pressurized to 272 atm (4000 psi). 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) and by central electrolysis using electricity from renewable sources. The main conclusions from the assessment are that the cryo-compressed storage system has the potential of meeting the ultimate target for system gravimetric capacity and the 2015 target for system volumetric capacity (see Table I). The system compares favorably with targets for durability and operability although additional work is needed to understand failure modes for combined pressure and temperature cycling. The system may meet the targets for hydrogen loss during dormancy under certain conditions of minimum daily driving. The high-volume manufacturing cost is projected to be 2-4 times the current 2010 target of $4/kWh. For the reference conditions considered most applicable, the fuel cost for the SMR hydrogen production and liquid H{sub 2} delivery scenario is 60%-140% higher than the current target of $2-$3/gge while the well-to-tank efficiency is well short of the 60% target specified for off-board regenerable materials.

  2. Localize.pytom: a modern webserver for cryo-electron tomography.

    PubMed

    Hrabe, Thomas

    2015-07-01

    Localize.pytom, available through http://localize.pytom.org is a webserver for the localize module in the PyTom package. It is a free website and open to all users and there is no login requirement. The server accepts tomograms as they are imaged and reconstructed by Cryo-Electron Tomography (CET) and returns densities and coordinates of candidate-macromolecules in the tomogram. Localization of macromolecules in cryo-electron tomograms is one of the key procedures to unravel structural features of imaged macromolecules. Positions of localized molecules are further used for structural analysis by single particle procedures such as fine alignment, averaging and classification. Accurate localization can be furthermore used to generate molecular atlases of whole cells. Localization uses a cross-correlation-based score and requires a reference volume as input. A reference can either be a previously detected macromolecular structure or extrapolated on the server from a specific PDB chain. Users have the option to use either coarse or fine angular sampling strategies based on uniformly distributed rotations and to accurately compensate for the CET common 'Missing Wedge' artefact during sampling. After completion, all candidate macromolecules cut out from the tomogram are available for download. Their coordinates are stored and available in XML format, which can be easily integrated into successive analysis steps in other software. A pre-computed average of the first one hundred macromolecules is also available for immediate download, and the user has the option to further analyse the average, based on the detected score distribution in a novel web-density viewer. PMID:25934806

  3. Localize.pytom: a modern webserver for cryo-electron tomography

    PubMed Central

    Hrabe, Thomas

    2015-01-01

    Localize.pytom, available through http://localize.pytom.org is a webserver for the localize module in the PyTom package. It is a free website and open to all users and there is no login requirement. The server accepts tomograms as they are imaged and reconstructed by Cryo-Electron Tomography (CET) and returns densities and coordinates of candidate-macromolecules in the tomogram. Localization of macromolecules in cryo-electron tomograms is one of the key procedures to unravel structural features of imaged macromolecules. Positions of localized molecules are further used for structural analysis by single particle procedures such as fine alignment, averaging and classification. Accurate localization can be furthermore used to generate molecular atlases of whole cells. Localization uses a cross-correlation-based score and requires a reference volume as input. A reference can either be a previously detected macromolecular structure or extrapolated on the server from a specific PDB chain. Users have the option to use either coarse or fine angular sampling strategies based on uniformly distributed rotations and to accurately compensate for the CET common ‘Missing Wedge’ artefact during sampling. After completion, all candidate macromolecules cut out from the tomogram are available for download. Their coordinates are stored and available in XML format, which can be easily integrated into successive analysis steps in other software. A pre-computed average of the first one hundred macromolecules is also available for immediate download, and the user has the option to further analyse the average, based on the detected score distribution in a novel web-density viewer. PMID:25934806

  4. Cryo-EM structure of the small subunit of the mammalian mitochondrial ribosome

    PubMed Central

    Kaushal, Prem S.; Sharma, Manjuli R.; Booth, Timothy M.; Haque, Emdadul M.; Tung, Chang-Shung; Sanbonmatsu, Karissa Y.; Spremulli, Linda L.; Agrawal, Rajendra K.

    2014-01-01

    The mammalian mitochondrial ribosomes (mitoribosomes) are responsible for synthesizing 13 membrane proteins that form essential components of the complexes involved in oxidative phosphorylation or ATP generation for the eukaryotic cell. The mammalian 55S mitoribosome contains significantly smaller rRNAs and a large mass of mitochondrial ribosomal proteins (MRPs), including large mito-specific amino acid extensions and insertions in MRPs that are homologous to bacterial ribosomal proteins and an additional 35 mito-specific MRPs. Here we present the cryo-EM structure analysis of the small (28S) subunit (SSU) of the 55S mitoribosome. We find that the mito-specific extensions in homologous MRPs generally are involved in inter-MRP contacts and in contacts with mito-specific MRPs, suggesting a stepwise evolution of the current architecture of the mitoribosome. Although most of the mito-specific MRPs and extensions of homologous MRPs are situated on the peripheral regions, they also contribute significantly to the formation of linings of the mRNA and tRNA paths, suggesting a tailor-made structural organization of the mito-SSU for the recruitment of mito-specific mRNAs, most of which do not possess a 5? leader sequence. In addition, docking of previously published coordinates of the large (39S) subunit (LSU) into the cryo-EM map of the 55S mitoribosome reveals that mito-specific MRPs of both the SSU and LSU are involved directly in the formation of six of the 15 intersubunit bridges. PMID:24799711

  5. Identification of volatile butyl rubber thermal-oxidative degradation products by cryofocusing gas chromatography/mass spectrometry (cryo-GC/MS).

    SciTech Connect

    Smith, Jonell Nicole; White, Michael Irvin; Bernstein, Robert; Hochrein, James Michael

    2013-02-01

    Chemical structure and physical properties of materials, such as polymers, can be altered as aging progresses, which may result in a material that is ineffective for its envisioned intent. Butyl rubber formulations, starting material, and additives were aged under thermal-oxidative conditions for up to 413 total days at up to 124 %C2%B0C. Samples included: two formulations developed at Kansas City Plant (KCP) (%236 and %2310), one commercially available formulation (%2321), Laxness bromobutyl 2030 starting material, and two additives (polyethylene AC-617 and Vanax MBM). The low-molecular weight volatile thermal-oxidative degradation products that collected in the headspace over the samples were preconcentrated, separated, and detected using cryofocusing gas chromatography mass spectrometry (cryo-GC/MS). The majority of identified degradation species were alkanes, alkenes, alcohols, ketones, and aldehydes. Observations for Butyl %2310 aged in an oxygen-18 enriched atmosphere (18O2) were used to verify when the source of oxygen in the applicable degradation products was from the gaseous environment rather than the polymeric mixture. For comparison purposes, Butyl %2310 was also aged under non-oxidative thermal conditions using an argon atmosphere.

  6. Electron microscopy. 2.2 Å resolution cryo-EM structure of ?-galactosidase in complex with a cell-permeant inhibitor.

    PubMed

    Bartesaghi, Alberto; Merk, Alan; Banerjee, Soojay; Matthies, Doreen; Wu, Xiongwu; Milne, Jacqueline L S; Subramaniam, Sriram

    2015-06-01

    Cryo-electron microscopy (cryo-EM) is rapidly emerging as a powerful tool for protein structure determination at high resolution. Here we report the structure of a complex between Escherichia coli ?-galactosidase and the cell-permeant inhibitor phenylethyl ?-D-thiogalactopyranoside (PETG), determined by cryo-EM at an average resolution of ~2.2 angstroms (Å). Besides the PETG ligand, we identified densities in the map for ~800 water molecules and for magnesium and sodium ions. Although it is likely that continued advances in detector technology may further enhance resolution, our findings demonstrate that preparation of specimens of adequate quality and intrinsic protein flexibility, rather than imaging or image-processing technologies, now represent the major bottlenecks to routinely achieving resolutions close to 2 Å using single-particle cryo-EM. PMID:25953817

  7. Zernike phase contrast cryo-electron microscopy reveals 100 kDa component in a protein complex

    NASA Astrophysics Data System (ADS)

    Wu, Yi-Min; Wang, Chun-Hsiung; Chang, Jen-wei; Chen, Yi-yun; Miyazaki, Naoyuki; Murata, Kazuyoshi; Nagayama, Kuniaki; Chang, Wei-Hau

    2013-12-01

    Cryo-electron microscopy (cryo-EM) has become a powerful technique for obtaining near atomic structures for large protein assemblies or large virus particles, but the application to protein particles smaller than 200-300 kDa has been hampered by the feeble phase contrast obtained for such small samples and the limited number of electrons tolerated by them without incurring excessive radiation damage. By implementing a thin-film quarter-wave phase plate to a cryo-EM, Nagayama, one of the present authors, has recently restored the long-lost very low spatial frequencies, generating in-focus phase contrast superior to that of conventional defocusing phase contrast, and successfully applied the so-called Zernike phase-plate cryo-EM to target various biological samples in native state. Nevertheless, the sought-after goal of using enhanced phase contrast to reveal a native protein as small as 100 kDa waits to be realized. Here, we report a study in which 200 kV Zernike phase-plate cryo-EM with a plate cut-on periodicity of 36 nm was applied to visualize 100 kDa components of various protein complexes, including the small domains on the surface of an icosahedral particle of ˜38 nm derived from the dragon grouper nervous necrosis virus (DGNNV) and the labile sub-complex dissociated from yeast RNA polymerase III of 17 nm. In the former case, we observed a phase contrast reversal phenomenon at the centre of the icosahedral particle and traced its root cause to the near matching of the cut-on size and the particle size. In summary, our work has demonstrated that Zernike phase-plate implementation can indeed expand the size range of proteins that can be successfully investigated by cryo-EM, opening the door for countless proteins. Finally, we briefly discuss the possibility of using a transfer lens system to enlarge the cut-on periodicity without further miniaturizing the plate pinhole.

  8. Single-walled carbon nanotubes and nanocrystalline graphene reduce beam-induced movements in high-resolution electron cryo-microscopy of ice-embedded biological samples

    Microsoft Academic Search

    Daniel Rhinow; Nils-Eike Weber; Andrey Turchanin; Armin Gölzhäuser; Werner Kühlbrandt

    2011-01-01

    For single particle electron cryo-microscopy (cryoEM), contrast loss due to beam-induced charging and specimen movement is a serious problem, as the thin films of vitreous ice spanning the holes of a holey carbon film are particularly susceptible to beam-induced movement. We demonstrate that the problem is at least partially solved by carbon nanotechnology. Doping ice-embedded samples with single-walled carbon nanotubes

  9. Impact of nanostructuring on the magnetic and magnetocaloric properties of microscale phase-separated La5/8–yPryCa3/8MnO? manganites

    DOE PAGESBeta

    Bingham, N. S.; Lampen, P.; Phan, M. H.; Hoang, T. D.; Chinh, H. D.; Zhang, C. L.; Cheong, S. W.; Srikanth, H.

    2012-08-01

    Bulk manganites of the form La5/8–yPryCa3/8MnO? (LPCMO) exhibit a complex phase diagram due to coexisting charge-ordered antiferromagnetic (CO/AFM), charge-disordered paramagnetic (PM), and ferromagnetic (FM) phases. Because phase separation in LPCMO occurs on the microscale, reducing particle size to below this characteristic length is expected to have a strong impact on the magnetic properties of the system. Through a comparative study of the magnetic and magnetocaloric properties of single-crystalline (bulk) and nanocrystalline LPCMO (y=3/8) we show that the AFM, CO, and FM transitions seen in the single crystal can also be observed in the large particle sizes (400 and 150 nm),more »while only a single PM to FM transition is found for the small particles (55 nm). Magnetic and magnetocaloric measurements reveal that decreasing particle size affects the balance of competing phases in LPCMO and narrows the range of fields over which PM, FM, and CO phases coexist. The FM volume fraction increases with size reduction, until CO is suppressed below some critical size, ~100 nm. With size reduction, the saturation magnetization and field sensitivity first increase as long-range CO is inhibited, then decrease as surface effects become increasingly important. The trend that the FM phase is stabilized on the nanoscale is contrasted with the stabilization of the charge-disordered PM phase occurring on the microscale, demonstrating that in terms of the characteristic phase separation length, a few microns and several hundred nanometers represent very different regimes in LPCMO.« less

  10. Spontaneous formation of an exchange-spring composite via magnetic phase separation in Pr{sub 1-x}Ca{sub x}CoO{sub 3}.

    SciTech Connect

    El-Khatib, S.; Bose, S.; He, C.; Kuplic, J.; Laver, M.; Borchers, J. A.; Huang, Q.; Lynn, J. W.; Mitchell, J. F.; Leighton, C.; Materials Science Division; Univ. of Minnesota; NIST; Univ. of Maryland

    2010-01-01

    We present a neutron-diffraction, small-angle scattering, and magnetometry study of the narrow bandwidth perovskite cobaltite Pr{sub 1-x}Ca{sub x}CoO{sub 3}, demonstrating an unusual form of magnetoelectronic phase separation where long-range ordered ferromagnetism coexists spatially with short-range ferromagnetism. The two phases have very different coercivities and, remarkably, are strongly exchange coupled. The electronic phase separation thus leads to spontaneous formation of a hard-soft nanocomposite, exhibiting prototypical exchange-spring behavior in the absence of chemical interfaces.

  11. Chromatographic Separations

    NSDL National Science Digital Library

    This interactive applet provides a simulation of the separation of a mixture of 5 substances across a chromatographic column. The effect of changing various chromatographic factors can simultaneously be seen in the time-dependent dedistribution of analytes along the column along with the development of the chromatogram.

  12. Charge transport in HoxLu1 -xB12 : Separating positive and negative magnetoresistance in metals with magnetic ions

    NASA Astrophysics Data System (ADS)

    Sluchanko, N. E.; Khoroshilov, A. L.; Anisimov, M. A.; Azarevich, A. N.; Bogach, A. V.; Glushkov, V. V.; Demishev, S. V.; Krasnorussky, V. N.; Samarin, N. A.; Shitsevalova, N. Yu.; Filippov, V. B.; Levchenko, A. V.; Pristas, G.; Gabani, S.; Flachbart, K.

    2015-06-01

    The magnetoresistance (MR) ? ? /? of the cage-glass compound HoxLu1 -xB12 with various concentrations of magnetic holmium ions (x ?0.5 ) has been studied in detail concurrently with magnetization M (T ) and Hall effect investigations on high-quality single crystals at temperatures 1.9-120 K and in magnetic field up to 80 kOe. The undertaken analysis of ? ? /? allows us to conclude that the large negative magnetoresistance (nMR) observed in the vicinity of the Néel temperature is caused by scattering of charge carriers on magnetic clusters of Ho3 + ions, and that these nanosize regions with antiferromagnetic (AF) exchange inside may be considered as short-range-order AF domains. It was shown that the Yosida relation -? ? /? ˜M2 provides an adequate description of the nMR effect for the case of Langevin-type behavior of magnetization. Moreover, a reduction of Ho-ion effective magnetic moments in the range 3-9 ?B was found to develop both with temperature lowering and under the increase of holmium content. A phenomenological description of the large positive quadratic contribution ? ? /? ˜?D2H2 which dominates in HoxLu1 -xB12 in the intermediate temperature range 20-120 K allows us to estimate the drift mobility exponential changes ?D˜T-? with ? =1.3 -1.6 depending on Ho concentration. An even more comprehensive behavior of magnetoresistance has been found in the AF state of HoxLu1 -xB12 where an additional linear positive component was observed and attributed to charge-carrier scattering on the spin density wave (SDW). High-precision measurements of ? ? /? =f (H ,T ) have allowed us also to reconstruct the magnetic H-T phase diagram of Ho0.5Lu0.5B12 and to resolve its magnetic structure as a superposition of 4 f (based on localized moments) and 5 d (based on SDW) components.

  13. Standardized Peptidome Profiling of Human Urine by Magnetic Bead Separation and Matrix-Assisted Laser Desorption\\/Ionization Time-of-Flight Mass Spectrometry

    Microsoft Academic Search

    Georg Martin Fiedler; Sven Baumann; Alexander Leichtle; Anke Oltmann; Julia Kase; Joachim Thiery; Uta Ceglarek

    Background: Peptidome profiling of human urine is a promising tool to identify novel disease-associated bi- omarkers; however, a wide range of preanalytical vari- ables influence the results of peptidome analysis. Our aim was to develop a standardized protocol for repro- ducible urine peptidome profiling by means of mag- netic bead (MB) separation followed by matrix-assisted

  14. DENGUE VIRUS. Cryo-EM structure of an antibody that neutralizes dengue virus type 2 by locking E protein dimers.

    PubMed

    Fibriansah, Guntur; Ibarra, Kristie D; Ng, Thiam-Seng; Smith, Scott A; Tan, Joanne L; Lim, Xin-Ni; Ooi, Justin S G; Kostyuchenko, Victor A; Wang, Jiaqi; de Silva, Aravinda M; Harris, Eva; Crowe, James E; Lok, Shee-Mei

    2015-07-01

    There are four closely-related dengue virus (DENV) serotypes. Infection with one serotype generates antibodies that may cross-react and enhance infection with other serotypes in a secondary infection. We demonstrated that DENV serotype 2 (DENV2)-specific human monoclonal antibody (HMAb) 2D22 is therapeutic in a mouse model of antibody-enhanced severe dengue disease. We determined the cryo-electron microscopy (cryo-EM) structures of HMAb 2D22 complexed with two different DENV2 strains. HMAb 2D22 binds across viral envelope (E) proteins in the dimeric structure, which probably blocks the E protein reorganization required for virus fusion. HMAb 2D22 "locks" two-thirds of or all dimers on the virus surface, depending on the strain, but neutralizes these DENV2 strains with equal potency. The epitope defined by HMAb 2D22 is a potential target for vaccines and therapeutics. PMID:26138979

  15. CryoEM reveals different coronin binding modes for ADP- and ADP-BeFx- actin filaments

    PubMed Central

    Ge, Peng; Oztug Durer, Zeynep A.; Kudryashov, Dmitri; Zhou, Z. Hong; Reisler, Emil

    2015-01-01

    Essential cellular processes involving the actin cytoskeleton are regulated by auxiliary proteins which can sense the nucleotide state of actin. Here we report cryo electron microscopy (cryoEM) structures at 8.6 Å resolution for ADP- and ADP-BeFx- (mimicking ADP-Pi) bound actin filaments in complex with the ?-propeller domain (residues 1–600) of yeast coronin 1 (crn1). Our structures identify the main differences in the interaction of coronin with the two nucleotide states of F-actin. We derived pseudo-atomic models by fitting the atomic structures of actin and coronin into these structures. The identified binding interfaces on actin were confirmed by chemical crosslinking, fluorescence spectroscopy and actin mutagenesis. Importantly, the structures of actin and coronin mapped in this study offer a structural explanation for the nucleotide-dependent effects of coronin on cofilin-assisted remodeling of F-actin. PMID:25362487

  16. Electron counting and beam-induced motion correction enable near atomic resolution single particle cryoEM

    PubMed Central

    Li, Xueming; Mooney, Paul; Zheng, Shawn; Booth, Chris; Braunfeld, Michael B.; Gubbens, Sander; Agard, David A.; Cheng, Yifan

    2013-01-01

    In recent work with large high symmetry viruses, single particle electron cryomicroscopy (cryoEM) has reached the milestone of determining near atomic resolution structures by allowing direct fitting of atomic models into experimental density maps. However, achieving this goal with smaller particles of lower symmetry remains extraordinarily challenging. Using a newly developed single electron counting detector, we confirm that electron beam induced motion significantly degrades resolution and, importantly, show how the combination of rapid readout and nearly noiseless electron counting allow image blurring to be corrected to subpixel accuracy. Thus, intrinsic image information can be restored to high resolution (Thon rings visible to ~3 Å). Using this approach we determined a 3.3 Å resolution structure of a ~700 kDa protein with D7 symmetry showing clear side chain density. Our method greatly enhances image quality and data acquisition efficiency - key bottlenecks in applying near atomic resolution cryoEM to a broad range of protein samples. PMID:23644547

  17. Removal of Hg(II) from aqueous solution by resin loaded magnetic ?-cyclodextrin bead and graphene oxide sheet: Synthesis, adsorption mechanism and separation properties.

    PubMed

    Cui, Limei; Wang, Yaoguang; Gao, Liang; Hu, Lihua; Wei, Qin; Du, Bin

    2015-10-15

    Resin loaded magnetic ?-cyclodextrin bead and graphene oxide sheet (MCD-GO-R) was synthesized successfully and found to be an excellent adsorbent for Hg(II) removal. The as-prepared adsorbent was characterized by SEM, FTIR, BET, magnetization curve and zeta potential analysis respectively. Good magnetic performance made MCD-GO-R simply recover from aqueous solution at low magnetic field within 30s. And also, the rich functional groups and outstanding dispersity play an important role in the adsorption process. The maximum adsorption capacity was 88.43mgg(-1) at 323K and pH 7.1. The as-prepared adsorbent could perform well in a wide pH range from 4.0 to 10.0. Static adsorption experimental data showed good correlation with pseudo-second-order model and Freundlich isotherm models. It was found that the contaminant adsorption was accomplished mainly via chelation or ion exchange and come to equilibrium in only 30min. All experimental results, especially the excellent reproducibility and resistance to ion interference, suggest that MCD-GO-R has promising applications in water treatment. PMID:26092115

  18. Ionic liquid-modified magnetic polymeric microspheres as dispersive solid phase extraction adsorbent: a separation strategy applied to the screening of sulfamonomethoxine and sulfachloropyrazine from urine.

    PubMed

    Yan, Hongyuan; Gao, Mengmeng; Yang, Chen; Qiu, Mande

    2014-04-01

    Ionic liquid-modified magnetic polymeric microspheres (ILMPM) were prepared based on Fe3O4 magnetic nanoparticles (MNPs) and ionic liquids (ILs) incorporated into a polymer. The composites were characterized using scanning electron microscopy, Fourier transform infrared analysis, thermogravimetric analysis, X-ray diffraction, and vibrating magnetometer, which indicated that ILMPM had a regularly spherical shape and strong magnetic property. The obtained ILMPM were successfully applied as a special adsorbent of magnetic dispersive solid phase extraction (MDSPE) for the rapid extraction and isolation of sulfamonomethoxine sodium and sulfachloropyrazine sodium in urine. The factors that affected extraction efficiency, such as adsorption conditions, desorption conditions, washing and elution solvents, and pH of the sample solution, were optimized. Under the optimum condition, good linearity in the range of 0.005-2.0 ?g g(-1) (r???0.9996) was obtained for the two sulfonamides (SAs); the average recoveries at three spiked levels ranged from 86.9 to 102.1 %, with relative standard deviations of ?4.3 %. The presented ILMPM-MDSPE method combined the advantages of ILs, MNPs, and MDSPE and therefore could be potentially applied for rapid screening of SAs in urine. PMID:24573579

  19. Structural Convergence between Cryo-EM and NMR Reveals Intersubunit Interactions Critical for HIV1 Capsid Function

    Microsoft Academic Search

    In-Ja L. Byeon; Xin Meng; Jinwon Jung; Gongpu Zhao; Ruifeng Yang; Jinwoo Ahn; Jiong Shi; Jason Concel; Christopher Aiken; Peijun Zhang; Angela M. Gronenborn

    2009-01-01

    SUMMARY Mature HIV-1 particles contain conical-shaped cap- sids that enclose the viral RNA genome and perform essential functions in the virus life cycle. Previous structural analysis of two- and three-dimensional arrays of the capsid protein (CA) hexamer revealed three interfaces. Here, we present a cryoEM study of a tubular assembly of CA and a high-resolution NMR structure of the CA

  20. Cryo-EM structure of the E. coli translating ribosome in complex with SRP and its receptor.

    PubMed

    Estrozi, Leandro F; Boehringer, Daniel; Shan, Shu-Ou; Ban, Nenad; Schaffitzel, Christiane

    2011-01-01

    We report the 'early' conformation of the Escherichia coli signal recognition particle (SRP) and its receptor FtsY bound to the translating ribosome, as determined by cryo-EM. FtsY binds to the tetraloop of the SRP RNA, whereas the NG domains of the SRP protein and FtsY interact weakly in this conformation. Our results suggest that optimal positioning of the SRP RNA tetraloop and the Ffh NG domain leads to FtsY recruitment. PMID:21151118

  1. Changes of Achilles Midportion Tendon Microcirculation After Repetitive Simultaneous Cryotherapy and Compression Using a Cryo\\/Cuff

    Microsoft Academic Search

    Karsten Knobloch; Ruth Grasemann; Michael Jagodzinski; Martinus Richter; Johannes Zeichen; Christian Krettek

    2006-01-01

    Background: Cryotherapy and compression have been shown to decrease pain and improve function. The dosage and timing of these options remain unclear.Purpose: To examine the effects of a standardized compression and cryotherapy device (Cryo\\/Cuff) on midportion Achilles tendon microcirculation during intermittent administration.Study Design: Descriptive laboratory study.Methods: Twenty-six subjects were included (13 men and 13 women; age, 32.3 ± 12 years;

  2. Cryo-analytical electron microscopy: new insight into the understanding of crystalline and electronic structure of silver halide

    Microsoft Academic Search

    V. P. Oleshko; R. H. Gijbels; W. A. Jacob

    1998-01-01

    Recent results of structural and analytical characterization of AgX (X equals Br, I) microcrystals of photographic emulsions by a number of cryo-analytical electron microscopy (AEM) and image analysis techniques are presented. Monte Carlo simulations of electron beam-AgX interactions have been made for a better understanding of relationships between various signals which can be analyzed in the corresponding AEM modes. Combined

  3. Internal structure and visualization of transmembrane domains of the RyR1 calcium release channel by cryo-EM

    Microsoft Academic Search

    Terence Wagenknecht; P D Allen; Montserrat Samsó

    2005-01-01

    RyR1 is an intracellular calcium channel with a central role in muscle contraction. We obtained a three-dimensional reconstruction of the RyR1 in the closed state at a nominal resolution of ?10 Å using cryo-EM. The cytoplasmic assembly consists of a series of interconnected tubular structures that merge into four columns that extend into the transmembrane assembly. The transmembrane assembly, which

  4. Quality control and validation of the new IOP and GOP ocean products from CryoSat-2

    NASA Astrophysics Data System (ADS)

    Calafat, Francisco M.; Cipollini, Paolo; Snaith, Helen; Bouffard, Jérôme; Féménias, Pierre; Parrinello, Tommaso

    2015-04-01

    CryoSat-2 is a huge asset to the oceanographic community, and the exploitation of its data over the ocean represents a welcome additional return for ESA's investment in a mission whose primary objective is to monitor the cryosphere. The CryoSat Project has approved, in the frame of the CryoSat routine phase, the generation of additional ocean products which are available since April 2014. These are the Interim Ocean Products (IOP), normally available within 2-3 day from acquisition, and the Geophysical Ocean Products (GOP), with consolidated orbits and available 30 days after acquisition. To enable their full exploitation by the scientific and operational oceanographic communities, these new ocean products need to be thoroughly quality-controlled and validated. Here we present the results of the scientific quality control performed at the UK National Oceanography Centre (NOC) within the framework of the CryOcean-QCV project. The assessment and quality control of the data is conducted both daily and monthly on a global scale for the L2 IOP and GOP products and includes coverage/completeness, data flow and latency analysis, along-track and crossover analysis, and estimation of error levels and measurement precision. Diagnostics are computed for the sea surface height (SSH), significant wave height (SWH), radar backscatter coefficient (sigma0), wind speed and mispointing parameters. In addition we present an absolute validation of the altimetric SSH for the GOP product against sea level observations from high-quality tide gauges equipped with Global Positioning System (GPS) receivers. Finally, the validation is extended by comparing the SSH from CryoSat-2 with that from other altimetric missions (Envisat, Jason-1 and Jason-2).

  5. 3D cryo-electron reconstruction of BmrA, a bacterial multidrug ABC transporter in an inward-facing conformation and in a lipidic environment.

    PubMed

    Fribourg, Pierre Frederic; Chami, Mohamed; Sorzano, Carlos Oscar S; Gubellini, Francesca; Marabini, Roberto; Marco, Sergio; Jault, Jean-Michel; Lévy, Daniel

    2014-05-15

    ABC (ATP-binding cassette) membrane exporters are efflux transporters of a wide diversity of molecule across the membrane at the expense of ATP. A key issue regarding their catalytic cycle is whether or not their nucleotide-binding domains (NBDs) are physically disengaged in the resting state. To settle this controversy, we obtained structural data on BmrA, a bacterial multidrug homodimeric ABC transporter, in a membrane-embedded state. BmrA in the apostate was reconstituted in lipid bilayers forming a mixture of ring-shaped structures of 24 or 39 homodimers. Three-dimensional models of the ring-shaped structures of 24 or 39 homodimers were calculated at 2.3 nm and 2.5 nm resolution from cryo-electron microscopy, respectively. In these structures, BmrA adopts an inward-facing open conformation similar to that found in mouse P-glycoprotein structure with the NBDs separated by 3 nm. Both lipidic leaflets delimiting the transmembrane domains of BmrA were clearly resolved. In planar membrane sheets, the NBDs were even more separated. BmrA in an ATP-bound conformation was determined from two-dimensional crystals grown in the presence of ATP and vanadate. A projection map calculated at 1.6 nm resolution shows an open outward-facing conformation. Overall, the data are consistent with a mechanism of drug transport involving large conformational changes of BmrA and show that a bacterial ABC exporter can adopt at least two open inward conformations in lipid membrane. PMID:24630999

  6. Selective separation and determination of the synthetic colorants in beverages by magnetic solid-phase dispersion extraction based on a Fe3 O4 /reduced graphene oxide nanocomposite followed by high-performance liquid chromatography with diode array detection.

    PubMed

    Wang, Xi; Chen, Ning; Han, Qing; Yang, Zaiyue; Wu, Jinhua; Xue, Cheng; Hong, Junli; Zhou, Xuemin; Jiang, Huijun

    2015-06-01

    A facile adsorbent, a nanocomposite of Fe3 O4 and reduced graphene oxide, was fabricated for the selective separation and enrichment of synthetic aromatic azo colorants by magnetic solid-phase dispersion extraction. The nanocomposite was synthesized in a one-step reduction reaction and characterized by atomic force microscopy, scanning electron microscopy, Fourier transform infrared spectroscopy, Raman spectroscopy, X-ray diffraction and Brunauer-Emmett-Teller analysis. The colorants in beverages were quickly adsorbed onto the surface of the nanocomposite with strong ?-? interactions between colorants and reduced graphene oxide, and separated with the assistance of an external magnetic field. Moreover, the four colorants in beverages were detected at different wavelengths by high performance liquid chromatography with diode array detection. A linear dependence of peak area was obtained over 0.05-10 ?g/mL with the limits of detection of 10.02, 11.90, 10.41, 15.91 ng/mL for tartrazine, allure red, amaranth, and new coccine, respectively (signal to noise = 3). The recoveries for the spiked colorants were in the range of 88.95-95.89% with the relative standard deviation less than 2.66%. The results indicated that the nanocomposite of Fe3 O4 and reduced graphene oxide could be used as an excellent selective adsorbent for aromatic compounds and has potential applications in sample pretreatment. PMID:25864558

  7. Effect of strain on the phase separation and devitrification of the magnetic glass state in thin films of La5/8 - yPryCa3/8MnO3 (y = 0.45)

    NASA Astrophysics Data System (ADS)

    Sathe, V. G.; Ahlawat, Anju; Rawat, R.; Chaddah, P.

    2010-05-01

    We present our study of the effect of substrate induced strain on La5/8 - yPryCa3/8MnO3 (y = 0.45) thin films grown on LaAlO3, NdGaO3 and SrTiO3 substrates that show large scale phase separation. It is observed that unstrained films grown on NdGaO3 behave quite similarly to bulk material but the strained films grown on SrTiO3 show melting of the insulating phase to the metallic phase at low temperatures. However, the large scale phase separation and metastable glass-like state is observed in all the films despite differences in substrate induced strain. The measurements of resistivity as a function of temperature under a cooling and heating in unequal field (CHUF) protocol elucidate the presence of a glass-like metastable phase generated due to kinetic arrest of the first order transformation in all the films. Like structural glasses, these magnetic glass-like phases show evidence of devitrification of the arrested charge order antiferromagnetic insulator (CO-AFI) phase to the equilibrium ferromagnetic metallic (FMM) phase with isothermal increase of magnetic field and/or iso-field warming. These measurements also clearly show the equilibrium ground state of this system to be FMM and the metastable glass-like phase to be AFI phase.

  8. Cryo-EM structure of the bacteriophage T4 portal protein assembly at near-atomic resolution

    PubMed Central

    Sun, Lei; Zhang, Xinzheng; Gao, Song; Rao, Prashant A.; Padilla-Sanchez, Victor; Chen, Zhenguo; Sun, Siyang; Xiang, Ye; Subramaniam, Sriram; Rao, Venigalla B.; Rossmann, Michael G.

    2015-01-01

    The structure and assembly of bacteriophage T4 has been extensively studied. However, the detailed structure of the portal protein remained unknown. Here we report the structure of the bacteriophage T4 portal assembly, gene product 20 (gp20), determined by cryo-electron microscopy (cryo-EM) to 3.6?Å resolution. In addition, analysis of a 10?Å resolution cryo-EM map of an empty prolate T4 head shows how the dodecameric portal assembly interacts with the capsid protein gp23 at the special pentameric vertex. The gp20 structure also verifies that the portal assembly is required for initiating head assembly, for attachment of the packaging motor, and for participation in DNA packaging. Comparison of the Myoviridae T4 portal structure with the known portal structures of ?29, SPP1 and P22, representing Podo- and Siphoviridae, shows that the portal structure probably dates back to a time when self-replicating microorganisms were being established on Earth. PMID:26144253

  9. Laboratory-based cryogenic soft x-ray tomography with correlative cryo-light and electron microscopy.

    PubMed

    Carlson, David B; Gelb, Jeff; Palshin, Vadim; Evans, James E

    2013-02-01

    Here we present a novel laboratory-based cryogenic soft X-ray microscope for whole cell tomography of frozen hydrated samples. We demonstrate the capabilities of this compact cryogenic microscope by visualizing internal subcellular structures of Saccharomyces cerevisiae cells. The microscope is shown to achieve better than 50 nm half-pitch spatial resolution with a Siemens star test sample. For whole biological cells, the microscope can image specimens up to 5 ?m thick. Structures as small as 90 nm can be detected in tomographic reconstructions following a low cumulative radiation dose of only 7.2 MGy. Furthermore, the design of the specimen chamber utilizes a standard sample support that permits multimodal correlative imaging of the exact same unstained yeast cell via cryo-fluorescence light microscopy, cryo-soft X-ray microscopy, and cryo-transmission electron microscopy. This completely laboratory-based cryogenic soft X-ray microscope will enable greater access to three-dimensional ultrastructure determination of biological whole cells without chemical fixation or physical sectioning. PMID:23332214

  10. Laboratory-Based Cryogenic Soft X-ray Tomography with Correlative Cryo-Light and Electron Microscopy

    SciTech Connect

    Carlson, David B.; Gelb, Jeff; Palshin, Vadim; Evans, James E.

    2013-02-01

    Here we present a novel laboratory-based cryogenic soft X-ray microscope for whole cell tomography of frozen hydrated samples. We demonstrate the capabilities of this compact cryogenic microscope by visualizing internal sub-cellular structures of Saccharomyces cerevisiae cells. The microscope is shown to achieve better than 50 nm spatial resolution with a Siemens star test sample. For whole biological cells, the microscope can image specimens up to 5 micrometers thick. Structures as small as 90 nm can be detected in tomographic reconstructions at roughly 70 nm spatial resolution following a low cumulative radiation dose of only 7.2 MGy. Furthermore, the design of the specimen chamber utilizes a standard sample support that permits multimodal correlative imaging of the exact same unstained yeast cell via cryo-fluorescence light microscopy, cryo-soft x-ray microscopy and cryo-transmission electron microscopy. This completely laboratory-based cryogenic soft x-ray microscope will therefore enable greater access to three-dimensional ultrastructure determination of biological whole cells without chemical fixation or physical sectioning.

  11. Advantages and safety features using foundation fieldbus-H1 based instrumentation & control for cryo system in accelerators

    NASA Astrophysics Data System (ADS)

    Kaushik, S.; Haneef, K. K. M.; Jayaram, M. N.; Lalsare, D. K.

    2008-05-01

    Large accelerator programme instrumentation and control for monitoring of large no. of parameters for cryogenic/cooling system. The parameters are Cryo Temperature, Vacuum, He Level and He flow etc. The circumference of the accelerator may vary up to several kilometers. Large size accelerators require huge cabling and hardware. The use of foundation fieldbus based Transmitters for measurement and Control valves field positioners for cryo system shall reduce the cabling, hardware, maintenance and enhance data processing and interoperability. Safety is an important requirement for efficient, trouble free and safe operation of any process industry such as cryo used in accelerators. Instrumentation and Control systems can be developed using Foundation Field Bus. The safety features in foundation field bus system can be achieved by use of intrinsic safe devices, fail safe configuration, minimize the hazard by distribution of control function blocks, short circuit preventers. Apart from above features, the significant cable reduction in the fieldbus system reduces the hazard due to electrical cable fire, which is considered one of the major risk in industry. Further the reliability in fieldbus can be improved by hot stand-by redundant power supply, hot stand-by redundant CPU, hot stand-by redundant network capability and use of link active scheduler.

  12. Low Cost, High Performance GPU Computing Solution for Atomic Resolution CryoEM Single-Particle Reconstruction

    PubMed Central

    Zhang, Xiaokang; Zhang, Xing; Zhou, Z. Hong

    2010-01-01

    Recent advancements in cryo-electron microscopy (cryoEM) have made it technically possible to determine the three-dimensional (3D) structures of macromolecular complexes at atomic resolution. However, processing the large amount of data needed for atomic resolution reconstructions requires either accessing to very expensive computer clusters or waiting for weeks of continuous computation in a personal computer (PC). In this paper, we present a practical computational solution to this 3D reconstruction problem through the optimal utilization of the processing capabilities of both commodity graphics hardware [i.e., general purpose graphics processing unit (GPGPU)]. Our solution, which is implemented in a new program, called eLite3D, has a number of advanced features of general interests. We construct interleaved schemes to prevent the data race condition intrinsic in merging of 2D data into a 3D volume. The speedup of eLite3D is up to 100 times over other commonly used 3D reconstruction programs with the same accuracy, thus allowing completion of atomic resolution 3D reconstructions of large complexes in a PC in 1–2 hours other than days or weeks. Our result provides a practical solution to atomic resolution cryoEM (asymmetric or symmetric) reconstruction and offers useful guidelines for developing GPGPU applications in general. PMID:20493949

  13. Cryo-EM structure of the bacteriophage T4 portal protein assembly at near-atomic resolution.

    PubMed

    Sun, Lei; Zhang, Xinzheng; Gao, Song; Rao, Prashant A; Padilla-Sanchez, Victor; Chen, Zhenguo; Sun, Siyang; Xiang, Ye; Subramaniam, Sriram; Rao, Venigalla B; Rossmann, Michael G

    2015-01-01

    The structure and assembly of bacteriophage T4 has been extensively studied. However, the detailed structure of the portal protein remained unknown. Here we report the structure of the bacteriophage T4 portal assembly, gene product 20 (gp20), determined by cryo-electron microscopy (cryo-EM) to 3.6?Å resolution. In addition, analysis of a 10?Å resolution cryo-EM map of an empty prolate T4 head shows how the dodecameric portal assembly interacts with the capsid protein gp23 at the special pentameric vertex. The gp20 structure also verifies that the portal assembly is required for initiating head assembly, for attachment of the packaging motor, and for participation in DNA packaging. Comparison of the Myoviridae T4 portal structure with the known portal structures of ?29, SPP1 and P22, representing Podo- and Siphoviridae, shows that the portal structure probably dates back to a time when self-replicating microorganisms were being established on Earth. PMID:26144253

  14. Histological structures of native and cooked yolks from duck egg observed by SEM and cryo-SEM.

    PubMed

    Hsu, Kuo-Chiang; Chung, Wen-Hsin; Lai, Kung-Ming

    2009-05-27

    A method was used to fix duck egg yolk while retaining its original sol structure to elucidate the fine structure of native yolk by using fixation with liquid nitrogen and cryo-scanning electron microscopy (cryo-SEM). Native yolk spheres showed a polyhedron shape with a diameter at approximately 50 to 100 ?m and packed closely together. Furthermore, the interior microstructure of the native yolk spheres showed that a great amount of round globules ranging from 0.5 to 1.5 ?m were embedded in a continuous phase with a lot of voids. After cooking, the sizes of the spheres were almost unchanged, and the continuous phase became a fibrous network structure observed by SEM with chemical fixation probably constituted of low density lipoprotein (LDL). The fine structure of the native yolk can be observed by cryo-SEM; however, the microstructure of yolk granules and plasma from cooked shell eggs can be observed by SEM with chemical fixation. PMID:19358603

  15. Cryo-EM structur