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1

COAL CLEANING BY HIGH GRADIENT MAGNETIC SEPARATION  

Microsoft Academic Search

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

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

1984-01-01

2

High gradient magnetic separation using a high temperature superconducting magnet  

Microsoft Academic Search

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

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

1998-01-01

3

HTS High Gradient Magnetic Separation system  

SciTech Connect

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

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

1996-09-01

4

High gradient magnetic separation using superconducting bulk magnets  

NASA Astrophysics Data System (ADS)

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

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

2003-10-01

5

High-gradient magnetic separation of coated magnetic nanoparticles  

Microsoft Academic Search

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

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

2004-01-01

6

TREATMENT OF COMBINED SEWER OVERFLOWS BY HIGH GRADIENT MAGNETIC SEPARATION  

EPA Science Inventory

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

7

Capture of metallic copper by high gradient magnetic separation system  

Microsoft Academic Search

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

P. K. Andy Hong

2011-01-01

8

High gradient magnetic separation applied to environmental remediation  

SciTech Connect

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

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

1993-08-01

9

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

Microsoft Academic Search

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

Nuray Karapinar

2003-01-01

10

Use of high gradient magnetic separation for actinide application  

SciTech Connect

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

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

1996-08-01

11

Modeling High Gradient Magnetic Separation in Biological Fluids  

NASA Astrophysics Data System (ADS)

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

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

2006-11-01

12

Application of high temperature superconductors to high-gradient magnetic separation  

Microsoft Academic Search

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

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

1994-01-01

13

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

PubMed Central

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

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

2009-01-01

14

Development of a high gradient magnetic separator using high temperature superconductors  

SciTech Connect

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

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

1996-09-01

15

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

Microsoft Academic Search

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

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

2002-01-01

16

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

Microsoft Academic Search

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

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

2010-01-01

17

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

Microsoft Academic Search

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

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

1981-01-01

18

Ramp rate testing of an HTS high gradient magnetic separation magnet  

SciTech Connect

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

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

1997-11-01

19

Removal of arsenic from geothermal water by high gradient magnetic separation  

Microsoft Academic Search

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

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

2002-01-01

20

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

NASA Astrophysics Data System (ADS)

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

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

2011-02-01

21

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

Microsoft Academic Search

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

Gareth P. Hatch; Richard E. Stelter

2001-01-01

22

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

NASA Astrophysics Data System (ADS)

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

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

2011-11-01

23

High-gradient magnetic separation in blood and bone marrow processing  

NASA Astrophysics Data System (ADS)

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

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

1990-04-01

24

Application of high gradient magnetic separation principles to magnetic drug targeting  

NASA Astrophysics Data System (ADS)

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

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

2004-09-01

25

Application of high temperature superconductors to high-gradient magnetic separation  

SciTech Connect

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

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

1994-06-01

26

Application of high temperature superconductors to high-gradient magnetic separation  

NASA Astrophysics Data System (ADS)

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

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

27

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

SciTech Connect

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

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

1998-12-01

28

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

SciTech Connect

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

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

1981-01-01

29

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

NASA Astrophysics Data System (ADS)

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

Ravnik, J.; Hriberšek, M.

2013-04-01

30

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

Microsoft Academic Search

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

D. Ito; K. Nishimura; O. Miura

2009-01-01

31

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

Microsoft Academic Search

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

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

2011-01-01

32

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

SciTech Connect

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

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

1991-03-01

33

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

NASA Astrophysics Data System (ADS)

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

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

2010-11-01

34

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

PubMed Central

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

2010-01-01

35

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

NASA Astrophysics Data System (ADS)

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

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

2011-05-01

36

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

NASA Astrophysics Data System (ADS)

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

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

2011-11-01

37

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

NASA Astrophysics Data System (ADS)

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

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

2010-11-01

38

Extraction of heavy metals using microorganisms and high gradient magnetic separation  

Microsoft Academic Search

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

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

1991-01-01

39

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

National Technical Information Service (NTIS)

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

D. R. Kelland

1983-01-01

40

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

NASA Astrophysics Data System (ADS)

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

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

2013-01-01

41

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

Microsoft Academic Search

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

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

2009-01-01

42

Paramagnetic microchip for high-gradient separation of blood cell  

NASA Astrophysics Data System (ADS)

This paper presents a magnetophoretic separation method on a chip of white blood cells from blood under continuous flow. The separation of red blood cells from the whole blood is performed using a high gradient magnetic separation method under continuous flow to trap the particles inside the device. The device is fabricated by microfabrication technology and enables to capture the red blood cells without the use of labelling tecniques such as magnetic beads. The method consists of flowing diluted whole blood through a microfluidic channel where a ferromagnetic layer, subjected to a permanent magnetic field, is located. The majority of red blood cells are trapped at the bottom of the device while the rest of the blood is collected at the outlet. Experimental results show that an average of 95% of red blood cells are trapped in the device.

Iliescu, Ciprian; Xu, Guolin; Barbarini, Elena; Avram, Marioara; Iliescu, Florina S.

2008-12-01

43

Influence of process variables in the high gradient separation of uranium ores  

SciTech Connect

Some uranium minerals are paramagnetic and hence are amenable to concentration by high gradient magnetic separation (HGMS). This paper describes effects of the HGMS parameters--pulp velocity, field strength, matrix loading, and magnetic field gradient--on the product recovery and grade. Unsatisfactory separation of uranium minerals by HGMS is related to ore-specific properties, such as lack of liberation, fine dissemination of uranium minerals, uniform distribution of magnetic minerals throughout the ore matrix, and interference of fine-sized slimes. Experimental techniques to identify and resolve some of these problems are outlined.

Malghan, S.G.; Van Dillen, J.P.

1983-12-01

44

High gradient magnetic beneficiation of dry pulverized coal via upwardly directed recirculating fluidization  

DOEpatents

This invention relates to an improved device and method for the high gradient magnetic beneficiation of dry pulverized coal, for the purpose of removing sulfur and ash from the coal whereby the product is a dry environmentally acceptable, low-sulfur fuel. The process involves upwardly directed recirculating air fluidization of selectively sized powdered coal in a separator having sections of increasing diameters in the direction of air flow, with magnetic field and flow rates chosen for optimum separations depending upon particulate size.

Eissenberg, David M. (Oak Ridge, TN); Liu, Yin-An (Opelika, AL)

1980-01-01

45

Ion imaging in a high-gradient magnetic guide  

SciTech Connect

We study a photoionization method to detect and image a narrow beam of cold atoms traveling along a high-gradient two-wire magnetic guide that is continuously on. Ions are accelerated in a compact acceleration region, directed through a drift region several centimeters in length, and detected using a position-sensitive ion detector. The potentials of several electrodes can be varied to adjust the imaging properties. Using ion trajectory simulations as well as experiments, we study the passage of the ions through the detection system, the magnification of the detection system, and the time-of-flight characteristics.

Vaidya, V. D. [JQI, University of Maryland, College Park, Maryland 20742 (United States); Traxler, M.; Mhaskar, R. R.; Raithel, G. [Department of Physics, University of Michigan, Ann Arbor, Michigan 48109 (United States); Hempel, C. [Institute for Quantum Optics and Quantum Information, Innsbruck A-6020 (Austria)

2010-04-15

46

Experimental Study on Capture of PM10 Emitted from Coal Combustion with High Gradient Magnetic Field  

NASA Astrophysics Data System (ADS)

Experiments on capturing PM10 emitted from coal combustion with high gradient magnetic field were carried out for the first time. A new fluidized bed aerosol generator was developed for generating fly ash aerosol with diameter less than 10?m constantly. The variation in the particle number concentration caused by high gradient magnetic field was measured with the Electrical Low Pressure Impactor (ELPI). Fly ash particles from combustion of three kinds of coal were sampled. Particle saturation magnetic moment is 0.37emu/g, 1.25emu/g, 2.00emu/g respectively. The results show that for the particles in the size range of 0.1?m~10?m particle capture efficiency varies from 25% to 40%. The particle with either larger or smaller size has higher capture efficiency, and the particle with medium size (1?m~3?m) has lower capture efficiency. The particle capture efficiency rises with increase in the particle magnetization, the magnetic field gradient and the filling ratio of ferromagnetic medium, and it reduces with increase in aerosol velocity. The present study indicates that high gradient magnetic separation is an effective way to control fine particle emission from coal combustion.

Lu, Duanfeng; Zhao, Changsui; Wu, Xin; Li, Yongwang; Han, Song

2007-06-01

47

High-Gradient Electromagnetic Separator with Continuous Slurry Extraction.  

National Technical Information Service (NTIS)

This kind of separator is operating without matrix in a cascade arrangement of conventional electromagnets. It is most suitable for continuous extraction of paramagnetic particulate solids in liquid suspensions. The water-cooled coils are supported by an ...

L. Dolle

1986-01-01

48

Tests of high gradient superconducting quadrupole magnets for the Tevatron  

SciTech Connect

Tests have been completed on three prototype magnets and two production magnets to be used for the Tevatron D{phi}/B{phi} low- {beta} insertion. These cold iron, two shell quadrupoles are made of 36 strand Rutherford type NbTi superconducting cable. Magnet field gradients well in excess of the design 1.41 T/cm have been achieved at a transfer function of 0.291 T/cm/kA. Quench performance at 4.2 K and 3.7 K and magnetic multipole measurement data are presented and discussed. 9 refs., 4 figs., 4 tabs.

Lamm, M.J.; Carson, J.; Gourlay, S.; Hanft, R.; Koepke, K.; Mantsch, P.; McInturff, A.D.; Riddiford, A.; Strait, J.

1989-09-01

49

Magnetic performance of new Fermilab high gradient quadrupoles  

SciTech Connect

For the Fermilab Tevatron low beta insertions installed in 1990--1991 as part of a luminosity upgrade there were built approximately 35 superconducting cold iron quadrupoles utilizing a two layer cos 2{theta} coil geometry with 76 mm diameter aperature. The field harmonics and strengths of these magnets obtained by measurement at cryogenic conditions are presented. Evidence for a longitudinal periodic structure in the remnant field is shown. 6 refs., 2 figs., 3 tabs.

Hanft, R.; Brown, B.C.; Carson, J.A.; Gourlay, S.A.; Lamm, M.J.; McInturff, A.D.; Mokhtarani, A.; Riddiford, A.

1991-05-01

50

High and ulta-high gradient quadrupole magnets  

SciTech Connect

Small bore conventional dc quadrupoles with apertures from 1 to 2.578cm were designed and prototypes built and measured. New fabrication techniques including the use of wire electric discharge milling (EDM) to economically generate the pole tip contours and aperture tolerances are described. Magnetic measurement data from a prototype of a 1cm aperture quadrupole with possible use in future e/sup +//e/sup -/ super colliders are presented. At a current of 400A, the lens achieved a gradient of 2.475 T/cm, and had an efficiency of 76.6%.

Brunk, W.O.; Walz, D.R.

1985-05-01

51

Multi-cycle recovery of lactoferrin and lactoperoxidase from crude whey using fimbriated high-capacity magnetic cation exchangers and a novel "rotor-stator" high-gradient magnetic separator.  

PubMed

Cerium (IV) initiated "graft-from" polymerization reactions were employed to convert M-PVA magnetic particles into polyacrylic acid-fimbriated magnetic cation exchange supports displaying ultra-high binding capacity for basic target proteins. The modifications, which were performed at 25?mg and 2.5?g scales, delivered maximum binding capacities (Qmax ) for hen egg white lysozyme in excess of 320?mg?g(-1) , combined with sub-micromolar dissociation constants (0.45-0.69?µm) and "tightness of binding" values greater than 49?L?g(-1) . Two batches of polyacrylic acid-fimbriated magnetic cation exchangers were combined to form a 5?g pooled batch exhibiting Qmax values for lysozyme, lactoferrin, and lactoperoxidase of 404, 585, and 685?mg?g(-1) , respectively. These magnetic cation exchangers were subsequently employed together with a newly designed "rotor-stator" type HGMF rig, in five sequential cycles of recovery of lactoferrin and lactoperoxidase from 2?L batches of a crude sweet bovine whey feedstock. Lactoferrin purification performance was observed to remain relatively constant from one HGMF cycle to the next over the five operating cycles, with yields between 40% and 49% combined with purification and concentration factors of 37- to 46-fold and 1.3- to 1.6-fold, respectively. The far superior multi-cycle HGMF performance seen here compared to that observed in our earlier studies can be directly attributed to the combined use of improved high capacity adsorbents and superior particle resuspension afforded by the new "rotor-stator" HGMS design. PMID:23335282

Brown, Geoffrey N; Müller, Christine; Theodosiou, Eirini; Franzreb, Matthias; Thomas, Owen R T

2013-02-22

52

Ultrastructure of pea and cress root statocytes exposed to high gradient magnetic field  

Microsoft Academic Search

As it was demonstrated by Kuznetsov & Hasenstein (1996) the high gradient magnetic field (HGMF) can produce a ponderomotive force that results in displacements of amyloplasts and causes the root response similar to the graviresponse. It was suggested that the HGMF could allow to imitate the effects of gravity in microgravity and\\/or change them in laboratory conditions correspondingly, as well

N. A. Belyavskaya; V. I. Chernishov; O. V. Polishchuk; A. V. Kondrachuk

2004-01-01

53

PILOT-SCALE FIELD TESTS OF HIGH-GRADIENT MAGNETIC FILTRATION  

EPA Science Inventory

The report gives results of using a 5100 cu m/hr mobile pilot plant to evaluate the effectiveness and economics of applying high-gradient magnetic filtration (HGMF) to particulate emission control. A 4-1/2 month test program was conducted at a Pennsylvania sintering plant to char...

54

Magnetic design of a high gradient quadrupole for the LHC low-{beta} insertions  

SciTech Connect

Fermilab, Lawrence Berkeley National Laboratory and Brookhaven National Laboratory have formed a consortium to provide components for the Large Hadron Collider (LHC) to be built at CERN. The U.S. contribution includes half of the high gradient quadrupoles (HGQ) for the inner focusing triplets. In this paper a description of the HGQ magnetic design is given, including short sample limit for field gradient, sources and expected values of systematic and random field errors, and possible strategies for field quality correction.

Sabbi, G.; Gourlay, S. A.; Kerby, J.; Limon, P. J.; Nobrega, F.; Novitski, I.; Strait, J. B.

1997-06-01

55

Performance results of a low current, high gradient superconducting quadrupole magnet  

SciTech Connect

A large bore, high gradient superconducting quadrupole magnet has been fabricated and tested which generates a gradient of 60 T/m in a cold bore 12.7 cm in diameter and 2.8 m long. The magnet operates safely without active quench protection and the unwanted multipole fields of the magnet sum to four parts per thousand at a bore radius of 5.0 cm. The magnet has been exposed to a neutral secondary beam at Fermilab produced by targeting a 400 GeV/c primary proton beam on a 30 cm Be target. When operated at a gradient of 52.5 T/m (86% of short sample) the magnet is quenched at a primary beam intensity of 6 x 10/sup 11/ protons per one second spill. The corresponding energy deposition in the magnet coils has been calculated to be 2 mJ/cm/sup 3/.

Smith, R.P.; Garbincius, P.H.; Gonczy, J.D.; Mazur, P.O.; Stanek, R.P.; Underwood, D.C.

1983-08-01

56

Magnetic separation for soil decontamination  

SciTech Connect

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

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

1993-01-01

57

Magnetic separation for soil decontamination  

SciTech Connect

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

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

1993-02-01

58

Numerical study of magnetic nanoparticles concentration in biofluid (blood) under influence of high gradient magnetic field  

NASA Astrophysics Data System (ADS)

Ferrofluids are widely used in pharmaceutical industries as magnetic separation tools, anti-cancer drug carriers and micro-valve applications. The purpose of the current study is to investigate the effect of a magnetic field on the volume concentration of magnetic nanoparticles of a non-Newtonian biofluid (blood) as a drug carrier. The effect of particles on the flow field is considered. The governing non-linear differential equations, concentration and Naviar-stokes are coupled with the magnetic field. To solve these equations, a finite volume based code is developed and utilized. The results show accumulation of magnetic nanoparticles near the magnetic source until it looks like a solid object. The accumulation of nanoparticles is due to the magnetic force that overcomes the fluid drag force. As the magnetic strength and size of the magnetic particles increase, the accumulation of nanoparticles increases, as well. The magnetic susceptibility of particles also affects the flow field and the contour of the concentration considerably.

Reza Habibi, Mohammad; Ghasemi, Majid

2011-01-01

59

A review of conductor performance for the LARP high-gradient quadrupole magnets  

NASA Astrophysics Data System (ADS)

We summarize critical current measurements and parameterizations of the data of 112 round wires and extracted strands that were reacted with the first 17 coils for the high-gradient quadrupole (HQ) magnets for the US LHC Accelerator Research Program (LARP). We standardize the strand parameterizations and coil ‘short sample’ calculations, and demonstrate that the entire critical current database can be captured in two scaling parameters per coil. These parameters summarize the short sample performance for each coil for either HQ magnet tests, or mirror tests of individual coils. We also demonstrate that for RRP® conductors, generic strain scaling parameters can be derived for at least four substantially different wire configurations, and standardize self-field corrections for LARP. The parameterized conductor performance is used to judge the performance of the HQ magnets and mirror tests. We find that although the HQ magnets reach around 86% of their short sample limitations, they are limited by factors other than the critical current of the conductor. Individual coils in mirror tests reach up to 98% of the expected performance, and do appear limited by the critical current of the conductor. Detailed analysis of short sample performance through accurate parameterizations simplifies the accessibility of short sample data, and enables accurate judgment of magnet performance as well as conductor and cable quality.

Godeke, A.; Chlachidze, G.; Dietderich, D. R.; Ghosh, A. K.; Marchevsky, M.; Mentink, M. G. T.; Sabbi, G. L.

2013-09-01

60

Hybrid magnet devices for molecule manipulation and small scale high gradient-field applications  

DOEpatents

The present disclosure provides a high performance hybrid magnetic structure made from a combination of permanent magnets and ferromagnetic pole materials which are assembled in a predetermined array. The hybrid magnetic structure provides means for separation and other biotechnology applications involving holding, manipulation, or separation of magnetizable molecular structures and targets. Also disclosed are hybrid magnetic tweezers able to exert approximately 1 nN of force to 4.5 .mu.m magnetic bead. The maximum force was experimentally measured to be .about.900 pN which is in good agreement with theoretical estimations and other measurements. In addition, a new analysis scheme that permits fast real-time position measurement in typical geometry of magnetic tweezers has been developed and described in detail.

Humphries, David E. (El Cerrito, CA); Hong, Seok-Cheol (Seoul, KR); Cozzarelli, legal representative, Linda A. (Berkeley, CA); Pollard, Martin J. (El Cerrito, CA); Cozzarelli, Nicholas R. (Berkeley, CA)

2009-01-06

61

Magnetotropism of roots and structure of their statocytes exposed to high gradient magnetic field  

NASA Astrophysics Data System (ADS)

In most living organisms gravity perception is based on the response of the gravisensing system to displacement of specific mass induced by a gravitational force The amyloplasts in higher plants are known to play the important role as the specific mass in gravisensing cells As was shown by Kuznetsov Hasenstein 1996 the high-gradient magnetic field HGMF exerts a directional ponderomotive force on such diamagnetic structures as amyloplasts This effect of the HGMF results in root curvature similar to that produced by gravity It was suggested that the HGMF could allow to imitate the effects of gravity in microgravity and or to change them in laboratory conditions correspondingly as well as to study statolith-related processes in graviperception Therefore the correlation between the direction of the ponderomotive force resulting in statolith displacements and the direction of the HGMF-induced plant curvature can be the serious argument to support this suggestion and needs the detailed structural analysis We have designed the HGMF facility that allows for generating the HGMF and analyzing its effects on higher plants roots The parameters of kinetics of Lepidium sativum L and Pisum sativum L root curvatures under both the HGMF action and gravistimulation were recorded by video system and measured by means of image analysis software The main results of the study are followings 1 the magnetotropic effect of the HGMF on root growth was found for pea and cress roots 2 the critical value of ponderomotive force that

Belyavskaya, N. A.; Polishchuk, O. V.; Kondrachuk, A. V.

62

Some effects of high- gradient magnetic field on tropism of roots of higher plants  

NASA Astrophysics Data System (ADS)

The perception of gravity in living organisms is mostly based on the response of the gravisensing system to displacement of some specific mass caused by gravitational force. According to the starch-statolith hypothesis the amyloplasts play the role of specific mass in gravisensing cells of higher plants. Kuznetsov & Hasenstein (1996) have demonstrated that the high-gradient magnetic field (HGMF) exerts a directional ponderomotive force on diamagnetic substances, in particular, statoliths. This effect of the HGMF causes root response similar to that produced by the change in gravity vector. Their studies supported the starch-statolith hypothesis and showed that ponderomotive force can be used to modify force acting on statoliths by manipulating statolith locations within gravisensing cells. We have designed the HGMF facility that allows for generating the HGMF and analyzing its effects on higher plants' roots. It records by videosystem and measures with the help of image analysis software the parameters of kinetics of root bending under both the HGMF action and gravistimulation. Two species of plants (pea and cress) have been examined. The main results of the work are the following: 1) The magnetotropic effect of HGMF on root growth was found for both species. 2) The critical value of ponderomotive force that caused the magnetotropic effect was estimated by modeling the magnetic field spatial distribution in the region of root apex. 3) The electron-microscopic analysis of statocytes after the HGMF treatment was carried out. The displacement of amyloplasts in root statocytes of two species of plants in HGMF was firstly demonstrated at the ultrastructural level. 4) Spatial distribution of exogenous proton fluxes (pH) along the roots was studied. The changes in pH distribution along curvature zone and apices of roots were revealed in the HGMF. It is known that application of HGMFs or strong uniform magnetic fields may influence ion transport due to Ampere force. It results in proton asymmetry relative to the root axis because the extent of changed H+ fluxes will depend on the intensity of the magnetic field. Thus, strong magnetic field can elicit asymmetric radial ion fluxes that, in turn, may be perceived as a directional stimulus. The estimates of these effects and the possible experiments to test these effects are proposed. 5) A theoretical analysis and modeling of optimal magnet configurations for the HGMF experiments as well as calculation of spatial distribution of ponderomotive force were carried out. The results are important for the qualitative treatment of the HGMF effects.

Kondrachuk, A.; Belyavskaya, N.

63

Magnetic Design of a High Gradient Quadrupole for the LHC Low-Beta Insertions.  

National Technical Information Service (NTIS)

Fermilab, Lawrence Berkeley National Laboratory and Brookhaven National Laboratory have formed a consor- tium to provide components for the Large Hadron Collider (LHC) to be built at CERN. The U.S. contribution includes half of the high gradient quadrupol...

G. Sabbi S. A. Gourlay J. Kerby M. J. Lamm P. J. Limon

2002-01-01

64

Permanently magnetized high gradient magnetic air filters for the nuclear industry  

Microsoft Academic Search

This paper describes the structure and testing of two novel permanently magnetized magnetic filters for fine radioactive material. In the first filter the holes in the filter are left open as capture proceeds which means the pressure drop builds up only slowly. This filter is not suitable for composite particles which can be broken by mechanical forces. The second filter

J. H. P. Watson

1995-01-01

65

Ultrastructure of pea and cress root statocytes exposed to high gradient magnetic field  

NASA Astrophysics Data System (ADS)

As it was demonstrated by Kuznetsov & Hasenstein (1996) the high gradient magnetic field (HGMF) can produce a ponderomotive force that results in displacements of amyloplasts and causes the root response similar to the graviresponse. It was suggested that the HGMF could allow to imitate the effects of gravity in microgravity and/or change them in laboratory conditions correspondingly, as well as to study statolith-related processes in graviperception. Therefore, the correlation between the direction of the ponderomotive force resulting in statolith displacements and the direction of the HGMF-induced plant curvature can be the serious argument to support this suggestion and needs the detailed ultrastructural analysis. Seeds of dicotyledon Pisum sativum L. cv. Damir-2 and monocotyledon Lepidium sativum L. cv. P896 were soaked and grown in a vertical position on moist filter paper in chambers at room temperature. Tips of primary roots of vertical control, gravistimulated and exposed to HGMF seedlings were fixed for electron microscopy using conventional techniques. At ultrastructural level, we observed no significant changes in the volume of the individual statocytes or amyloplasts, relative volumes of cellular organelles (except vacuoles), number of amyloplasts per statocyte or surface area of endoplasmic reticulum. No consistent contacts between amyloplasts and any cellular structures, including plasma membrane, were revealed at any stage of magneto- and gravistimulation. By 5 min after onset of magnetostimulation, amyloplasts were located along cell wall distant from magnets. In HGMF, the locations of amyloplasts in columella cells were similar to those in horizontally-oriented roots up to 1 h stimulation. In the latter case, there were sometimes cytoplasmic spherical bodies with a dense vesicle-rich cytoplasm in pea statocytes, which were absent in seedlings exposed to HGMF. In cress root statocytes, both gravi- and magnetostimulation were found to cause the appearance of significant amounts of electron-dense granules in the cytoplasm and the nucleus (particularly, in the nucleolus); the effect was most evident in HGMF. Testing the chemical composition of such deposits is going on. The data presented statocyte responses indicate similarity the effects of magneto- and gravistimulation at the ultrastructural level. Thus, the root curvature in HGMF is the plant response to displacement of amyloplasts by ponderomotive force, which can serve as tool for investigation of graviperception mechanism and can provide directional stimulus for plant growth in microgravity. (Financial support by STCU: NN-13R).

Belyavskaya, N. A.; Chernishov, V. I.; Polishchuk, O. V.; Kondrachuk, A. V.

66

Magnetic Separation of Soluble Organic Pollutants from Water.  

National Technical Information Service (NTIS)

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

J. A. Petruska J. V. Perumpral

1977-01-01

67

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

Microsoft Academic Search

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

Song Huiping; Cheng Huaigang; Li Xingang; Cheng Fangqin

2012-01-01

68

Magnetic Separation Device.  

National Technical Information Service (NTIS)

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

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

1985-01-01

69

Magnetic separation of uranium from magnesium fluoride  

SciTech Connect

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

Hoegler, J.M.

1987-01-01

70

Magnetic separation for environmental remediation  

SciTech Connect

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

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

1994-11-01

71

A safe, low current, high gradient, superconducting quadrupole magnet for high energy physics beam transport  

Microsoft Academic Search

A superconducting quadrupole magnet has been fabricated and tested that generates a gradient of 60 T\\/m at a peak operating current of 1100 amperes. The cold bore of the magnet is 12.7 cm in diameter and 2.8 m long, and the unwanted field multipoles sum to 4 parts per thousand of the quadrupole field at a bore radius of 5.0

R. Smith; S. Kim; C. Krieger; J. Gonczy; A. Kelly; D. Underwood; E. Wallace; K. Wiggins; P. Garbincius; P. Mazur; R. Stanek

1983-01-01

72

A Novel High-Gradient Permanent Magnet for the Profiling of Planar Films and Coatings  

NASA Astrophysics Data System (ADS)

The design and construction of a low-cost, permanent magnet is described. The magnet is intended for applications which require a large static gradient, such as those for which stray field imaging or fringe field diffusometry are conventionally employed. The magnet has been designed using the scalar potential method. Particular features of the magnet include a field profile such that ||B|| is constant in the horizontal plane and such that B is horizontal at the midpoint between the poles. There is a vertical, and therefore orthogonal, strong gradient, G, in ||B||. The ratio G/||B|| is constant within a large volume and so allows measurements at a range of gradient strengths. It is this ratio which governs the shape of the pole-pieces. The constructed magnet has a typical operating field of 0.8 T, gives a gradient of 20 Tm-1, and has a useable interpole access of 20 mm. Field plot data show values consistent with the theory. In particular ||B|| has a curvature of less than +/-5 ?m over a 5 x 5 mm area at the target field. The magnet is most suitable for the one-dimensional profiling of thin planar samples. As an example of the magnet's use, a profile of a sandwich structure made of several polymer layers is shown. In addition, a set of one-dimensional profiles of an alkyd coating, recorded during solvent loss and cross-linking, is presented. This example demonstrates quantitative T2 measurements at a resolution of 6.5 ?m across a 70-?m-thick film.

Glover, P. M.; Aptaker, P. S.; Bowler, J. R.; Ciampi, E.; McDonald, P. J.

1999-07-01

73

A novel high-gradient permanent magnet for the profiling of planar films and coatings.  

PubMed

The design and construction of a low-cost, permanent magnet is described. The magnet is intended for applications which require a large static gradient, such as those for which stray field imaging or fringe field diffusometry are conventionally employed. The magnet has been designed using the scalar potential method. Particular features of the magnet include a field profile such that ||B || is constant in the horizontal plane and such that B is horizontal at the midpoint between the poles. There is a vertical, and therefore orthogonal, strong gradient, G, in ||B ||. The ratio G/ ||B || is constant within a large volume and so allows measurements at a range of gradient strengths. It is this ratio which governs the shape of the pole-pieces. The constructed magnet has a typical operating field of 0.8 T, gives a gradient of 20 Tm-1, and has a useable interpole access of 20 mm. Field plot data show values consistent with the theory. In particular ||B || has a curvature of less than +/-5 microm over a 5 x 5 mm area at the target field. The magnet is most suitable for the one-dimensional profiling of thin planar samples. As an example of the magnet's use, a profile of a sandwich structure made of several polymer layers is shown. In addition, a set of one-dimensional profiles of an alkyd coating, recorded during solvent loss and cross-linking, is presented. This example demonstrates quantitative T2 measurements at a resolution of 6.5 microm across a 70-microm-thick film. PMID:10388588

Glover, P M; Aptaker, P S; Bowler, J R; Ciampi, E; McDonald, P J

1999-07-01

74

A safe, low current, high gradient, superconducting quadrupole magnet for high energy physics beam transport  

SciTech Connect

A superconducting quadrupole magnet has been fabricated and tested that generates a gradient of 60 T/m at a peak operating current of 1100 amperes. The cold bore of the magnet is 12.7 cm in diameter and 2.8 m long, and the unwanted field multipoles sum to 4 parts per thousand of the quadrupole field at a bore radius of 5.0 cm. The magnet operates safely without quench protection and peak coil temperatures following quenches deliberately induced at full field do not exceed 50 K. Testing at the design gradient of 50 T/m indicates a beam energy deposition quench threshold of approximately 5 mJ/cm/sup 3/.

Smith, R.; Gonczy, J.; Kelly, A.; Kim, S.; Krieger, C.; Underwood, D.; Wallace, E.; Wiggins, K.

1983-05-01

75

Validation of High Gradient Magnetic Field Based Drug Delivery to Magnetizable Implants Under Flow  

Microsoft Academic Search

The drug-eluting stent's increasingly frequent occurrence late stage thrombosis have created a need for new strategies for intervention in coronary artery disease. This paper demonstrates further development of our minimally invasive, targeted drug delivery system that uses induced magnetism to administer repeatable and patient specific dosages of therapeutic agents to specific sites in the human body. Our first aim is

Zachary G. Forbes; Benjamin B. Yellen; Derek S. Halverson; Gregory Fridman; Kenneth A. Barbee; Gary Friedman

2008-01-01

76

Magnetic separation anxiety  

SciTech Connect

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

Canning, C.

1992-01-01

77

Superconducting magnetic separation  

SciTech Connect

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

Kopp, J.

1988-03-01

78

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

National Technical Information Service (NTIS)

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

V. Bureau

1993-01-01

79

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

Microsoft Academic Search

Prevention of eutrophication for semi-enclosed bays and ponds is serious and important challenge. In spite of the advanced wastewater treatment, typically 1mg\\/L phosphorus is discharged into public water bodies from wastewater treatment plants. The total amount of the discharged water is so large that the further improvement of the removal efficiency of phosphorus in the discharged water is demanded. On

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

2010-01-01

80

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

NASA Astrophysics Data System (ADS)

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

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

2013-01-01

81

Continuous magnetic separator and process  

DOEpatents

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

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

2008-04-22

82

Analytical methods for separating and isolating magnetic nanoparticles.  

PubMed

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

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

2012-02-03

83

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

SciTech Connect

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

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

1994-01-14

84

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

SciTech Connect

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

Not Available

1994-04-01

85

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

SciTech Connect

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

Not Available

1993-06-01

86

Multilayer High-Gradient Insulators  

SciTech Connect

Multilayer High-Gradient Insulators are vacuum insulating structures composed of thin, alternating layers of dielectric and metal. They are currently being developed for application to high-current accelerators and related pulsed power systems. This paper describes some of the High-Gradient Insulator research currently being conducted at Lawrence Livermore National Laboratory.

Harris, J R

2006-08-16

87

Magnetic Separation for Nuclear Material Detection and Surveillance  

SciTech Connect

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

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

1998-08-01

88

Doxorubicin magnetic conjugate targeting upon intravenous injection into mice: High gradient magnetic field inhibits the clearance of nanoparticles from the blood  

NASA Astrophysics Data System (ADS)

The efficiency of a stationary magnetic field (|?B|=200mT/cm) in increasing the bioavailability of a doxorubicin-magnetite nanoparticle conjugate (diameter of 24±19 nm) in the mouse lung was determined by pharmacokinetic investigation using electron spin resonance (ESR). The magnetic field was also found to inhibit the elimination of nanoparticles from the blood and increase the conjugate half-life and bioavailability in the blood.

Mykhaylyk, Olga; Dudchenko, Nataliya; Dudchenko, Alexandre

2005-05-01

89

Separation of magnetic field lines  

SciTech Connect

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

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

2012-11-15

90

Magnetic separation of antibiotics by electrochemical magnetic seeding  

Microsoft Academic Search

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

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

2009-01-01

91

Isolation of Bowman-Birk-Inhibitor from soybean extracts using novel peptide probes and high gradient magnetic separation.  

PubMed

Soybean proteins offer exceptional promise in the area of cancer prevention and treatment. Specifically, Bowman-Birk Inhibitor (BBI) has the ability to suppress carcinogenesis in vivo, which has been attributed to BBI's inhibition of serine protease (trypsin and chymotrypsin) activity. The lack of molecular probes for the isolation of this protein has made it difficult to work with, limiting its progress as a significant candidate in the treatment of cancer. This study has successfully identified a set of novel synthetic peptides targeting the BBI, and has demonstrated the ability to bind BBI in vitro. One of those probes has been covalently immobilised on superparamagnetic microbeads to allow the isolation of BBI from soy whey mixtures in a single step. Our ultimate goal is the use of the described synthetic probe to facilitate the isolation of this potentially therapeutic protein for low cost, scalable analysis and production of BBI. PMID:23442627

Fields, Conor; Mallee, Paul; Muzard, Julien; Lee, Gil U

2012-03-30

92

Multilayer High-Gradient Insulators  

SciTech Connect

High voltage systems operated in vacuum require insulating materials to maintain spacing between conductors held at different potentials, and may be used to maintain a nonconductive vacuum boundary. Traditional vacuum insulators generally consist of a single material, but insulating structures composed of alternating layers of dielectric and metal can also be built. These ''High-Gradient Insulators'' have been experimentally shown to withstand higher voltage gradients than comparable conventional insulators. As a result, they have application to a wide range of high-voltage vacuum systems where compact size is important. This paper describes ongoing research on these structures, as well as the current theoretical understanding driving this work.

Harris, J R; Anaya, R M; Blackfield, D; Chen, Y -; Falabella, S; Hawkins, S; Holmes, C; Paul, A C; Sampayan, S; Sanders, D M; Watson, J A; Caporaso, G J; Krogh, M

2006-11-15

93

Magnetic separation techniques: their application to medicine  

Microsoft Academic Search

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

J. T. Kemsheadl; J. Ugelstad

1985-01-01

94

The magnets of the GSI fragment separator  

SciTech Connect

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

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

1994-07-01

95

Reciprocating Magnetic Separator. Final Report.  

National Technical Information Service (NTIS)

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

2008-01-01

96

Magnetic separation in water pollution control  

Microsoft Academic Search

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

CHRISTOPHER DE LATOUR

1973-01-01

97

Development of magnetic separation system of magnetoliposomes  

NASA Astrophysics Data System (ADS)

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

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

2009-10-01

98

Polarized electrons from high-gradient guns  

SciTech Connect

To take advantage of the lower emittance associated with extraction fields >> 10 MV/m, a number of technological hurdles must be overcome before photocathodes appropriate for generating polarized electrons can be utilized in high-gradient guns. Both rf guns and very fast ultra-high gradient ({ge} 1 GV/m) diode guns are anticipated. The known problems--some of which may be more than just technical--are delineated, and the present status of relevant research is reviewed.

Clendenin, J.E.; Mulhollan, G.A.

1998-09-01

99

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

NASA Astrophysics Data System (ADS)

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

Khashan, Saud A.; Furlani, Edward P.

2013-03-01

100

Research and Development for Ultra-High Gradient Accelerator Structures  

SciTech Connect

Research on the basic physics of high-gradient, high frequency accelerator structures and the associated RF/microwave technology are essential for the future of discovery science, medicine and biology, energy and environment, and national security. We will review the state-of-the-art for the development of high gradient linear accelerators. We will present the research activities aimed at exploring the basic physics phenomenon of RF breakdown. We present the experimental results of a true systematic study in which the surface processing, geometry, and materials of the structures have been varied, one parameter at a time. The breakdown rate or alternatively, the probability of breakdown/pulse/meter has been recorded for different operating parameters. These statistical data reveal a strong dependence of breakdown probability on surface magnetic field, or alternatively on surface pulsed heating. This is in contrast to the classical view of electric field dependence.

Tantawi, Sami G.; Dolgashev, Valery [SLAC National Accelerator Laboratory, 2575 Sand Hill Rd, Menlo Park, CA 94305 (United States); Higashi, Yasuo [High Energy Accelerator Research Organization, KEK, 1-1 Oho, Tsukuba, Ibaraki 305-0801 (Japan); Spataro, Bruno [INFN-LNF, 00044 Frascati (Italy)

2010-11-04

101

Beneficiation with Magnetic Fluids—Magnetic Separation of the Second Kind  

Microsoft Academic Search

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

S. E. KHALAFALLA

1985-01-01

102

Designs for a Microfabricated Magnetic Sifter  

Microsoft Academic Search

A microfabricated magnetic sifter has been designed and fabricated for applications in biological sample preparation. The device enables high-throughput, high-gradient magnetic separation of magnetic nanoparticles by utilizing parallel fluid flow through a dense array (~500 \\/mm2 ) of micropatterned slots in a magnetically soft membrane. Finite element models have been carried out to map the magnetic field and magnetic field

Christopher M. Earhart; Evelyn M. Nguyen; Robert J. Wilson; Y. Andrew Wang; Shan X. Wang

2009-01-01

103

Relativistic klystrons for high-gradient accelerators  

SciTech Connect

Experimental work is being performed by collaborators at LLNL, SLAC, and LBL to investigate relativistic klystrons as a possible rf power source for future high-gradient accelerators. We have learned how to overcome or previously reported problem of high power rf pulse shortening and have achieved peak rf power levels of 330 MW using an 11.4-GHz high-gain tube with multiple output structures. In these experiments the rf pulse is of the same duration as the beam current pulse. In addition, experiments have been performed on two short sections of a high-gradient accelerator using the rf power from a relativistic klystron. An average accelerating gradient of 84 MV/m has been achieved with 80-MW of rf power.

Westenskow, G.A.; Aalberts, D.P.; Boyd, J.K.; Deis, G.A.; Houck, T.L.; Orzechowski, T.J.; Ryne, R.D.; Yu, S.S. (Lawrence Livermore National Lab., CA (USA)); Allen, M.A.; Callin, R.S.; Deruyter, H.; Eppley, K.R.; Fant, K.S.; Fowkes, W.R.; Hoag, H.A.; Koontz, R.F.; Lavine, T.L.; Loew, G.A.; Miller, R.H.; Ruth, R.D.; Vlieks, A.E.; Wang, J.W. (Stanford Linear Accelerator Center, Menlo Park, CA (USA)); Haimson, J.; Mecklen

1990-09-05

104

Advanced High Gradient RF Structure Development  

SciTech Connect

Multi-mode accelerating structures aimed at increasing accelerating gradient are described. Such structures operating in several resonant, equidistantly-spaced, axisymmetric, TM-like eigenmodes allow reduction of exposure time to surface fields, reduction of high-field areas and reduction of those fields which are responsible for electron emission. These effects are planned for use in studying the physics of RF breakdown phenomenon with the goal of designing new high-gradient accelerating structures.

Kuzikov, S. V. [Institute of Applied Physics, Russian Academy of Sciences, 46 Ulyanov St., Nizhny Novgorod, 603950 (Russian Federation); Omega-P, Inc., 258 Bradley St., New Haven, CT 06510 (United States); Kazakov, S. Yu. [Omega-P, Inc., 258 Bradley St., New Haven, CT 06510 (United States); Fermi National Accelerator Laboratory, Batavia, IL (United States); Jiang, Y. [Yale University, New Haven, CT (United States); Plotkin, M. E.; Vikharev, A. A. [Institute of Applied Physics, Russian Academy of Sciences, 46 Ulyanov St., Nizhny Novgorod, 603950 (Russian Federation); Hirshfield, J. L. [Omega-P, Inc., 258 Bradley St., New Haven, CT 06510 (United States); Yale University, New Haven, CT (United States)

2010-11-04

105

MSWI boiler fly ashes: magnetic separation for material recovery.  

PubMed

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

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

2011-02-08

106

Fundamental study of phosphor separation by controlling magnetic force  

NASA Astrophysics Data System (ADS)

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

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

2013-11-01

107

Performance of HGMS filter and recycling of magnetic seeding material on magnetic seeding method  

SciTech Connect

The optimum conditions for the recovery of nonmagnetic particles were obtained using a HGMS (high gradient magnetic separation) filter on the magnetic seeding method. The performance of the filter was given by the magnetic separator equations. In addition, it was found from the experimental results that the recycling of 95% magnetic seeding material was practicable.

Kurinobu, Shuntaro; Uesugi, Jun; Utumi, Yasusi; Kasahara, Hiroshi

1999-09-01

108

Relativistic klystron research for high gradient accelerators  

SciTech Connect

Relativistic klystrons are being developed as a power source for high gradient accelerator applications which include large linear electron--positron colliders, compact accelerators, and FEL sources. We have attained 200MW peak power at 11.4 GHz from a relativistic klystron, and 140 MV/m longitudinal gradient in a short 11.4 GHz accelerator section. We report here on the design of our first klystrons, the results of our experiments so far, and some of our plans for the near future. 5 refs., 7 figs.

Allen, M.A.; Callin, R.S.; Deruyter, H.; Eppley, K.R.; Fowkes, W.R.; Herrmannsfeldt, W.B.; Higo, T.; Hoag, H.A.; Lavine, T.L.; Lee, T.G.

1988-06-01

109

High gradient experiments on NLCTA accelerator structures  

SciTech Connect

This paper presents new results of high-gradient studies performed on a 1.8 m traveling-wave accelerator section with detuned high-order deflecting modes. This structure was designed initially for studies of detuned structures and will be installed in the Next Linear Collider Test Accelerator (NLCTA). The paper describes the test set-up in the Accelerator Structure Test Area (ASTA) including electron gun, prebuncher, pre-accelerator, spectrometer, Faraday cups, 200 MW SLED-II power compression system, Magic-T type phase shifters and attenuators. Rf processing, detailed dark current analysis, radiation problems, and beam acceleration measurements are discussed.

Wang, J.W.; Eichner, J.P.; Fant, K.H. [and others

1996-08-01

110

Integrated acoustic and magnetic separation in microfluidic channels  

PubMed Central

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

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

2009-01-01

111

Waste Remediation Using in Situ Magnetically Assisted Chemical Separation  

Microsoft Academic Search

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

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

1995-01-01

112

Waste remediation using in situ magnetically assisted chemical separation  

Microsoft Academic Search

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

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

1993-01-01

113

Magnetically separable composite photocatalyst with enhanced photocatalytic activity.  

PubMed

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

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

2008-03-08

114

Magnetic field and gradient analysis around matrix for HGMS  

Microsoft Academic Search

A High Gradient Magnetic Separator (HGMS) uses matrix to make high magnetic field gradient so that ferro- or para-magnetic particles can be attracted to them by high magnetic force. These matrixes are usually composed of stainless wires having high magnetization characteristics. This paper deals with superconducting HGMS which is aimed for purifying wastewater by using stainless steel matrix. Background magnetic

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

2010-01-01

115

High Gradient Operation with the CEBAF Upgrade RF Control System  

SciTech Connect

The CEBAF Accelerator at Jefferson Lab is presently a 6 GeV five pass electron accelerator consisting of two superconducting linacs joined by independent magnetic transport arcs. Energy will be upgraded to 12 GeV with the addition of 10 new high gradient cryomodules (17+ MV/m). The higher gradients pose significant challenges beyond what the present analog low level RF (LLRF) control systems can handle reliably; therefore, a new LLRF control system is needed. A prototype system has been developed incorporating a large FPGA and using digital down and up conversion to minimize the need for analog components. The new system is more flexible and less susceptible to drifts and component nonlinearities. Because resonance control is critical to reach high gradients quickly, the new cryomodules will include a piezoelectric tuner for each cavity, and the LLRF controls must incorporate both feedback and feed-forward methods to achieve optimal resonance control performance. This paper discusses development of the new RF system, system performance for phase and amplitude stability and resonance control under Lorentz detuning measured during recent tests on a prototype cryomodule.

J. Hovater; G. Davis; Hai Dong; Alicia Hofler; Lawrence King; John Musson; Tomasz Plawski

2006-08-16

116

High Gradient Wakefields in Dielectric Loaded Structures  

SciTech Connect

Dielectric loaded wakefield structures have potential to be used as high gradient accelerator components. Using the high current drive beam at the Argonne Wakefield Accelerator Facility, we employed cylindrical dielectric loaded wakefield structures to generate accelerating fields of up to 86 MV/m, at 10 GHz. Short electron bunches of up to 86 nC are used to drive these fields, either as single bunches or as bunch trains. The structures consist of cylindrical ceramic tubes (cordierite) with a dielectric constant of 4.76, inserted into cylindrical copper waveguides. These standing-wave structures have a field probe near the outer diameter of the dielectric, in order to sample the RF fields generated by the electron bunches. Monitoring the field probe signal serves to verify the absence of electric breakdown in the structures. MAFIA simulations are used to calculate the amplitude of the fields generated by the traversing electrons bunches.

Conde, M. E.; Franchini, F.; Gai, W.; Konecny, R.; Liu, W.; Power, J. G.; Yusof, Z. [Argonne National Laboratory, 9700 South Cass Avenue, Argonne, IL 60439 (United States); Antipov, S.; Gao, F.; Wang, H. [Illinois Institute of Technology, 3300 South Federal Street, Chicago, IL 60616 (United States); Jing, C. [Euclid TechLabs, 5900 Harper Road, Solon, OH 44139 (United States)

2006-11-27

117

Phase separation in aqueous magnetic colloidal solutions  

Microsoft Academic Search

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

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

118

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

SciTech Connect

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

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

1997-01-01

119

Cell Separation Using Protein-A-Coated Magnetic Nanoclusters  

Microsoft Academic Search

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

Srinivas V. Sonti; Arijit Bose

1995-01-01

120

Self-Assembled Magnetic Filter for Highly Efficient Immunomagnetic Separation  

PubMed Central

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

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

2010-01-01

121

Magnetically separable nanocatalysts: bridges between homogeneous and heterogeneous catalysis.  

PubMed

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

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

2010-05-01

122

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

Microsoft Academic Search

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

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

1995-01-01

123

Performances of a waste recycling separator with permanent magnets  

Microsoft Academic Search

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

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

2007-01-01

124

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

DOEpatents

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

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

2010-02-09

125

Separation and acceleration of magnetic monopole analogs in semiconductor microcavities  

NASA Astrophysics Data System (ADS)

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

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

2012-08-01

126

Hydrophobic partitioning approach to efficient protein separation with magnetic nanoparticles  

Microsoft Academic Search

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

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

2010-01-01

127

Using magnetic levitation to separate mixtures of crystal polymorphs.  

PubMed

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

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

2013-08-12

128

Separation of Fullerence Molecules in an Eletric-Magnetic Isotope Separator  

Microsoft Academic Search

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

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

1993-01-01

129

Development of a high gradient quadrupole for the LHC interaction regions  

Microsoft Academic Search

A collaboration of Fermilab, Lawrence Berkeley National Laboratory and Brookhaven National Laboratory is engaged in the design of a high gradient quadrupole suitable for use in the LHC interaction regions. The cold iron design incorporates a two-layer, cos(2?) coil geometry with a 70 mm aperture operating in superfluid helium. This paper summarizes the progress on a magnetic, mechanical and thermal

R. Bossert; S. Feher; S. A. Gourlay; T. Heger; Y. Huang; J. Kerby; M. J. Lamm; P. J. Limon; P. O. Mazur; F. Nobrega; J. P. Ozelis; G. Sabbi; J. Strait; A. V. Zlobin; S. Caspi; D. Dell'orco; A. D. McInturff; R. M. Scanlan; J. M. Van Oort; R. C. Gupta

1997-01-01

130

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

Microsoft Academic Search

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

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

2008-01-01

131

Waste remediation using in situ magnetically assisted chemical separation  

SciTech Connect

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

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

1993-11-01

132

Measurement of time dependent fields in high gradient superconducting quadrupoles for the Tevatron  

SciTech Connect

Magnetic field measurements have been performed on prototype and production magnets from two high gradient superconducting quadrupoles designs. One design is a double shell quadrupole with 36 strand Rutherford cable. The other design is a single shell quadrupole with 5 individually monolithic strands connected in series. These magnets have similar bore diameters and cable dimensions. However, there are significant differences between the two designs, as well as differences between prototype and production magnets within each design, with regard to Cu to superconductor ratio, filament diameter and filament spacing to strand diameter. The time dependence of fixed currents of the measured magnetic fields is discussed. 9 refs., 6 figs., 1 tab.

Lamm, M.J.; Coulter, K.; Gourlay, S.; Jaffery, T.S.

1990-10-01

133

End design of the SSC 58 mm High Gradient Quadrupole  

SciTech Connect

The ``end`` design of the High Gradient Quad. was done with consideration to the integrated field harmonics, the iron contribution, and the maximum field at the conductor. Magnetic analysis was done on the return end only, however the physical dimension of the lead end were determined as well. Using the cross-section of the windings and Cook`s program BEND, we generated the physical end windings around the return end. Placing a single wire at the center of each turn the integrated gradient was computed and iterating on the end block spacers the integrated harmonics minimized. The final geometry was then used for more, extensive calculations, such as the field at the conductor and the 3D field harmonics. For this detailed calculation we have placed a single line current at the center of each strand and included the iron contribution ({mu} = {infinity}), see Appendix C. With the termination of the iron serving as a reference, the maximum length of the inner and outer layers are 182 mm and 215 mm respectively. The magnetic length of the end was computed from the gradient function A{sub 2} and was found to be 142 mm. In reality we expect the physical length of the end to be somewhat larger, however this should have little or no effect on the magnetic length. The gradient in the straight section is 212.44 T/m at 7000 A and the integrated value of the gradient is -3.01665 E5 (G) in the end region marked by the magnetic length of the end. The respective integrated harmonics for the end 12 pole and 20 pole are -10.6658 (G/CM{sup 4}) and 0.7279 (G/cm{sup 8}) corresponding to b{sub 6} = 0.351 , b{sub 10} = -0.024 units. The above was computed from the values of A{sub 2}, A{sub 6}, and A{sub 10}.

Caspi, S.

1992-06-10

134

End design of the SSC 58 mm High Gradient Quadrupole  

SciTech Connect

The end'' design of the High Gradient Quad. was done with consideration to the integrated field harmonics, the iron contribution, and the maximum field at the conductor. Magnetic analysis was done on the return end only, however the physical dimension of the lead end were determined as well. Using the cross-section of the windings and Cook's program BEND, we generated the physical end windings around the return end. Placing a single wire at the center of each turn the integrated gradient was computed and iterating on the end block spacers the integrated harmonics minimized. The final geometry was then used for more, extensive calculations, such as the field at the conductor and the 3D field harmonics. For this detailed calculation we have placed a single line current at the center of each strand and included the iron contribution ({mu} = {infinity}), see Appendix C. With the termination of the iron serving as a reference, the maximum length of the inner and outer layers are 182 mm and 215 mm respectively. The magnetic length of the end was computed from the gradient function A{sub 2} and was found to be 142 mm. In reality we expect the physical length of the end to be somewhat larger, however this should have little or no effect on the magnetic length. The gradient in the straight section is 212.44 T/m at 7000 A and the integrated value of the gradient is -3.01665 E5 (G) in the end region marked by the magnetic length of the end. The respective integrated harmonics for the end 12 pole and 20 pole are -10.6658 (G/CM{sup 4}) and 0.7279 (G/cm{sup 8}) corresponding to b{sub 6} = 0.351 , b{sub 10} = -0.024 units. The above was computed from the values of A{sub 2}, A{sub 6}, and A{sub 10}.

Caspi, S.

1992-06-10

135

Study on industrial wastewater treatment using superconducting magnetic separation  

Microsoft Academic Search

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

Hao Zhang; Zhengquan Zhao; Xiangdong Xu; Laifeng Li

2011-01-01

136

Silica coated magnetic nanoparticles for separation of nuclear acidic waste  

SciTech Connect

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

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

2010-05-15

137

The study on optimization issues for magnetic separation by magnetic chromatography  

NASA Astrophysics Data System (ADS)

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

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

2010-11-01

138

Photocatalytic magnetic separable beads for chromium (VI) reduction.  

PubMed

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

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

2009-11-26

139

Research and Development of Magnetic Purification System for Used Wash Water of Drum  

Microsoft Academic Search

A high gradient magnetic separation system for purifying used wash water of drum was developed. The waste water is a mixture of various types of contaminant. The wastewater is made into floe containing ferromagnetic particles in the magnetic seeding tank. The magnetic seeded waste water is pumped into the high speed magnetic sedimentation device equipped with multiple permanent magnets. The

F. Mishima; Y. Akiyama; S. Nishijima

2010-01-01

140

Magnetic separation as a plutonium residue enrichment process  

SciTech Connect

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

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

1989-01-01

141

Magnetic Separations with Magnetite: Theory, Operation, and Limitations  

SciTech Connect

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

G. B. Cotten

2000-08-01

142

Endotoxin removal by magnetic separation-based blood purification.  

PubMed

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

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

2012-12-06

143

Separation of impurity in molten metals by using superconducting magnet  

NASA Astrophysics Data System (ADS)

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

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

2009-10-01

144

Design Studies of Nb3Sn High-Gradient Quadrupole Models for LARP  

SciTech Connect

Insertion quadrupoles with large aperture and high gradient are required to achieve the luminosity upgrade goal of 10{sup 35} cm{sup -2} s{sup -1} at the Large Hadron Collider (LHC). In 2004, the US Department of Energy established the LHC Accelerator Research Program (LARP) to develop a technology base for the upgrade. Nb{sub 3}Sn conductor is required in order to operate at high field and with sufficient temperature margin. We report here on the conceptual design studies of a series of 1 m long 'High-gradient Quadrupoles' (HQ) that will explore the magnet performance limits in terms of peak fields, forces and stresses. The HQ design is expected to provide coil peak fields of more than 15 T, corresponding to gradients above 300 T/m in a 90 mm bore. Conductor requirements, magnetic, mechanical and quench protection issues for candidate HQ designs will be presented and discussed.

Sabbi, GianLuca; Andreev, Nikolai; Caspi, Shlomo; Dietderich, Daniel; Ferracin, Paolo; Ghosh, Arup; Kashikhin, Vadim; Lietzke, Al; McInturff, Alfred; Novitski, Igor; Zlobin, Alexander

2007-06-01

145

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

NASA Astrophysics Data System (ADS)

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

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

2012-12-01

146

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

Microsoft Academic Search

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

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

1994-01-01

147

Radiolysis and hydrolysis of magnetically assisted chemical separation particles  

SciTech Connect

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

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

1995-05-01

148

A high-gradient high-duty-factor Rf photo-cathode electron gun  

SciTech Connect

We describe the analysis and preliminary design of a high-gradient, high-duty factor RF photocathode gun. The gun is designed to operate at high repetition rate or CW, with high gradient on the cathode surface to minimize emittance growth due to space charge forces at high bunch charge. The gun may also be operated in a solenoidal magnetic field for emittance compensation. The design is intended for use in short-pulse, high-charge, and high-repetition rate applications such as linac based X-ray sources. We present and compare the results of gun simulations using different codes, as well as RF and thermal analysis of the structure.

Rimmer, Robert A.; Hartman, Neal; Lidia, Steven M.; Wang, Shaoheng

2002-05-22

149

Plasma separation process: Magnet move to Oak Ridge National Laboratory  

SciTech Connect

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

Not Available

1989-07-01

150

Apparatus for magnetic separation of paramagnetic and diamagnetic material  

DOEpatents

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

Doctor, R.D.

1988-10-18

151

Charge separation of plasma flow in curvilinear magnetic field  

NASA Astrophysics Data System (ADS)

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

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

2012-03-01

152

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

Microsoft Academic Search

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

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

2011-01-01

153

High-gradient two-beam accelerator structure  

Microsoft Academic Search

A novel cavity structure is described that could be the basis for a two-beam, high-gradient, accelerator. Versions of the structure could be used for acceleration of beams of electrons, positrons, muons, protons, or heavier ions; with either electron or proton drive beams. The structure embodies cavities that are excited in several harmonically related eigenmodes, such that rf fields reach their

S. Yu Kazakov; S. V. Kuzikov; Y. Jiang; J. L. Hirshfield

2010-01-01

154

Second generation high gradient quadrupoles for the LHC interaction regions  

Microsoft Academic Search

Conceptual designs of large-aperture high-gradient Nb3Sn quadrupoles, suitable for use in a second generation LHC interaction region, are presented. A quadrupole with a 90 mm coil aperture and the same 200 T\\/m gradient as in the current LHC IR is technically feasible and would allow ?*=0.25 in to be achieved, doubling the LHC luminosity

T. Sen; J. Strait; A. V. Zlobin

2001-01-01

155

Summary Report of Working Group 2: High-Gradient Structures  

NASA Astrophysics Data System (ADS)

We give a summary of the presentations and discussions that took place in the High Gradient Structures Working Group at the 2006 Advanced Accelerator Concepts Workshop. Following the working group mission statement and charge, the talks are listed, with brief descriptions and highlights of the discussions that they generated.

Tantawi, Sami G.; Dolgashev, Valery A.

2006-11-01

156

Rotation therapy using a novel high-gradient filter  

SciTech Connect

A rotation therapy technique developed for treatment of head and neck tumors produced a sharp dose gradient between the target volume and the organ at risk, the medulla spinalis. To produce this effect, a specially designed high-gradient filter was placed in the photon beam.

Lax, I.; Brahme, A.

1982-11-01

157

Summary Report of Working Group 2: High-Gradient Structures  

SciTech Connect

We give a summary of the presentations and discussions that took place in the High Gradient Structures Working Group at the 2006 Advanced Accelerator Concepts Workshop. Following the working group mission statement and charge, the talks are listed, with brief descriptions and highlights of the discussions that they generated.

Tantawi, Sami G.; Dolgashev, Valery A. [Stanford Linear Accelerator Center, Menlo Park, CA 94025 (United States)

2006-11-27

158

On-chip Magnetic Separation and Cell Encapsulation in Droplets  

NASA Astrophysics Data System (ADS)

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

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

2012-02-01

159

Plasma separation process: Magnet move to Oak Ridge National Laboratory  

NASA Astrophysics Data System (ADS)

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

1989-07-01

160

Magnetic and fluorescence-encoded polystyrene microparticles for cell separation  

NASA Astrophysics Data System (ADS)

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

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

2008-12-01

161

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

NASA Astrophysics Data System (ADS)

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

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

2009-10-01

162

Experimental and theoretical investigation of high gradient acceleration  

SciTech Connect

This report contains a technical progress summary of the research conducted under the auspices of DOE Grant No. DE-AC02-91-ER40648, Experimental and Theoretical Investigations of High Gradient Acceleration''. This grant supports three research tasks: Task A consists of the design, fabrication and testing of a 17GHz RF photocathode gun, which can produce 2ps electron pulses with up to 1nC of charge at 2MeV energy and at a 1OHz repetition rate. Task B supports the testing of high gradient acceleration at 33GHz structure, and Task C comprises theoretical investigations, both in support of the experimental tasks and on critical physics issues for the development of high energy linear colliders.

Wurtele, J.S.; Bekefi, G.; Chen, C.; Chen, S.C.; Temkin, R.J.

1993-01-01

163

High-gradient electron accelerator powered by a relativisitic klystron  

SciTech Connect

We have used relativistic klystron technology to extract 290 MW of peak power at 11.4 GHz from an induction linac beam, and to power a short 11.4-GHz high-gradient accelerator. We have measured rf phase stability, field emission, and the momentum spectrum of an accelerated electron beam. An average accelerating gradient of 84 MV/m has been achieved with 80 MW of relativistic klystron power.

Allen, M.A.; Boyd, J.K.; Callin, R.S.; Deruyter, H.; Eppley, K.R.; Fant, K.S.; Fowkes, W.R.; Haimson, J.; Hoag, H.A.; Hopkins, D.B.; Houck, T.; Koontz, R.F.; Lavine, T.L.; Loew, G.A.; Mecklenburg, B.; Miller, R.H.; Ruth, R.D.; Ryne, R.D.; Sessler, A.M.; Vlieks, A.E.; Wang, J.W.; Westenskow, G.A.; Yu, S.S. (Stanford Linear Accelerator Center, Stanford University, Stanford, California 94309 (USA) Lawrence Livermore National Laboratory, Livermore, California 94550 (USA) Haimson Research Corporation, Palo Alto, California 94303 (USA))

1989-11-27

164

Design and testing of a high gradient radio frequency cavity for the muon collider  

NASA Astrophysics Data System (ADS)

This thesis describes the design and testing of a high gradient RF cavity for the muon cooling channel of the muon collider. The 805 MHz multi-cell open iris cavity was high power tested with a 12 MW klystron in a superconducting solenoid environment. The cavity reached 21 MV/m for peak klystron power in the absence of the solenoidal field. During magnetic field operation, the cavity suffered serious surface damage and RF breakdown. Dark current in excess of 400 mA was observed. Present R&D results imply that the cavity is not suitable for the muon collider.

Wu, Vincent

165

Development of a high gradient quadrupole for the LHC Interaction Regions  

SciTech Connect

A collaboration of Fermilab, Lawrence Berkeley National Laboratory and Brookhaven National Laboratory is engaged in the design of a high gradient quadrupole suitable for use in the LHC interaction regions. The cold iron design incorporates a two-layer, cos(2{theta}) coil geometry with a 70 mm aperture operating in superfluid helium. This paper summarizes the progress on a magnetic, mechanical and thermal design that meets the requirements of maximum gradient above 250 T/m, high field quality and provision for adequate cooling in a high radiation environment.

Bossert, R.; Feher, S.; Gourlay, S.A. [and others

1997-04-01

166

Design of a High Gradient Quadrupole for the LHC Interaction Regions  

SciTech Connect

A collaboration of Fermilab, Lawrence Berkeley National Laboratory and Brookhaven National Laboratory is currently engaged in the design of a high gradient quadrupole suitable for use in the LHC interaction regions. The cold iron design incorporates a two-shell, cos2{theta} coil geometry with a 70 mm aperture. This paper summarizes the progress on a magnetic and mechanical design that meets the requirements of maximum gradient {>=}250 T/m, operation at 1.8K, high field quality and provision for adequate cooling in a high radiation environment.

Bossert, R.; Gourlay, S.A.; Heger, T.; Huang, Y.; Kerby, J.; Lamm, M.J.; Limon, P.J.; Mazur, P.O.; Nobrega, F.; Ozelis, J.P.; Sabbi, G.; Strait, J.; Zlobin, A.V.; Caspi, S. [Lawrence Berkeley National Lab., CA (United States); Dell`orco, D. [Lawrence Berkeley National Lab., CA (United States); McInturff, A.D. [Lawrence Berkeley National Lab., CA (United States); Scanlan, R.M. [Lawrence Berkeley National Lab., CA (United States); Van Oort, J.M. [Lawrence Berkeley National Lab., CA (United States); Gupta, R.C. [Brookhaven National Lab., Upton, NY (United States)

1997-03-01

167

Dielectric-Lined High-Gradient Accelerator Structure  

SciTech Connect

Rectangular particle accelerator structures with internal planar dielectric elements have been studied, with a view towards devising structures with lower surface fields for a given accelerating field, as compared with structures without dielectrics. Success with this concept is expected to allow operation at higher accelerating gradients than otherwise on account of reduced breakdown probabilities. The project involves studies of RF breakdown on amorphous dielectrics in test cavities that could enable high-gradient structures to be built for a future multi-TeV collider. The aim is to determine what the limits are for RF fields at the surfaces of selected dielectrics, and the resulting acceleration gradient that could be achieved in a working structure. The dielectric of principal interest in this study is artificial CVD diamond, on account of its advertised high breakdown field ({approx}2 GV/m for dc), low loss tangent, and high thermal conductivity. Experimental studies at mm-wavelengths on materials and structures for achieving high acceleration gradient were based on the availability of the 34.3 GHz third-harmonic magnicon amplifier developed by Omega-P, and installed at the Yale University Beam Physics Laboratory. Peak power from the magnicon was measured to be about 20 MW in 0.5 {micro}s pulses, with a gain of 54 dB. Experiments for studying RF high-field effects on CVD diamond samples failed to show any evidence after more than 10{sup 5} RF pulses of RF breakdown up to a tangential surface field strength of 153 MV/m; studies at higher fields were not possible due to a degradation in magnicon performance. A rebuild of the tube is underway at this writing. Computed performance for a dielectric-loaded rectangular accelerator structure (DLA) shows highly competitive properties, as compared with an existing all-metal structure. For example, comparisons were made of a DLA structure having two planar CVD diamond elements with a all-metal CERN structure HDS operating at 30 GHz. It was shown that the ratio of maximum surface electric field to accelerating field at the metal wall is only 0.35-0.4 for DLA, much smaller than the value 2.2 for HDS; and the ratio of surface magnetic field to accelerating field is 3.0 mA/V for DLA, compared with 3.45 mA/V for HDS. These values bode well for DLA in helping to avoid breakdown and to reducing pulsed surface heating and fatigue. The shunt impedance is found to be 160-175 M{Omega}/m for DLA, as compared to 99 M{Omega}/m for HDS. Conclusions are reached from this project that CVD diamond appears promising as a dielectric with a high threshold for RF breakdown, and that rectangular accelerator structures can be devised using planar CVD diamond elements that could be operated at higher acceleration gradients with low probability of RF breakdown, as compared with corresponding all-metallic structures.

Jay L. Hirshfield

2012-04-24

168

Selective separation of proteins with pH-dependent magnetic nanoadsorbents  

Microsoft Academic Search

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

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

2007-01-01

169

Magnetic separator having high rate of field change capability  

SciTech Connect

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

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

1990-12-18

170

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

DOEpatents

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

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

1980-11-06

171

New process for placer gold recovery by means of magnetic separation  

Microsoft Academic Search

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

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

1992-01-01

172

High efficiency protein separation with organosilane assembled silica coated magnetic nanoparticles  

Microsoft Academic Search

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

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

2008-01-01

173

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...

174

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

National Technical Information Service (NTIS)

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

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

1999-01-01

175

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

Microsoft Academic Search

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

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

2009-01-01

176

Enhanced separation of magnetic and diamagnetic particles in a dilute ferrofluid  

NASA Astrophysics Data System (ADS)

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

Liang, Litao; Zhang, Cheng; Xuan, Xiangchun

2013-06-01

177

Development of X-band accelerating structures for high gradients  

NASA Astrophysics Data System (ADS)

Short copper standing wave (SW) structures operating at an X-band frequency have been recently designed and manufactured at the Laboratori Nazionali di Frascati of the Istituto Nazionale di Fisica Nucleare (INFN) using the vacuum brazing technique. High power tests of the structures have been performed at the SLAC National Accelerator Laboratory. In this manuscript we report the results of these tests and the activity in progress to enhance the high gradient performance of the next generation of structures, particularly the technological characterization of high performance coatings obtained via molybdenum sputtering.

Bini, S.; Chimenti, V.; Marcelli, A.; Palumbo, L.; Spataro, B.; A. Dolgashev, V.; Tantawi, S.; D. Yeremian, A.; Higashi, Y.; G. Grimaldi, M.; Romano, L.; Ruffino, F.; Parodi, R.

2012-07-01

178

Factors limiting the operation of structures under high gradient  

SciTech Connect

Factors limiting the operation of rf structures under high-gradient conditions are described. Included are recent rf measurements at laboratories in Europe, Asia, and North America and how these measurements relate to earlier data as exemplified by the use of the Kilpatrick criterion (Kp). Operation limitations will cover mechanical, geometry, thermal, and surface constraints and the associated impact on structure design, fabrication, and material selection. Generally, structures operating continuous wave (100% duty factor) appear to be limited to peak surface fields at about twice the Kilpatrick limit, whereas pulsed structures operating with pulse lengths less than a millisecond can attain peak surface fields five times the Kilpatrick limit.

Schriber, S.O.

1986-01-01

179

Measured and Theoretical Characterization of the RF Properties of Stacked, High-Gradient Insulator Material.  

National Technical Information Service (NTIS)

Recent high-voltage breakdown experiments of periodic metallic-dielectric insulating structures have suggested several interesting high-gradient applications. One such area is the employment of high-gradient insulators in high-current, electron-beam, acce...

G. J. Caporaso C. C. Shang S. E. Sampayan N. E. Molau M. L. Krogh

1997-01-01

180

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

Microsoft Academic Search

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

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

2004-01-01

181

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

NASA Astrophysics Data System (ADS)

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

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

2013-11-01

182

Magnetic particles for the separation and purification of nucleic acids  

Microsoft Academic Search

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

Sonja Berensmeier

2006-01-01

183

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

Microsoft Academic Search

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

J Svoboda; C Coetzee; Q. P Campbell

1998-01-01

184

Modified Magnicon for High-Gradient Accelerator R&D  

SciTech Connect

Analysis, and low-power cold tests are described on a modified design intended for the Ka-band pulsed magnicon now in use for high-gradient accelerator R and D and rare elementary particle searches at the Yale University Beam Physics Laboratory. The modification is mainly to the output cavity of the magnicon, which presently operates in the TM310 mode. It is proposed to substitute for this a dual-chamber TE311 cavity structure. The first chamber is to extract about 40% of the beam power (about 25 MW) at 34.272 GHz, while the second chamber is to convey the power to four WR-28 output waveguides. Minor design changes are also proposed for the penultimate 11.424 GHz cavity and the beam collector. The intention of these design changes is to allow the magnicon to operate reliably 24/7, with minor sensitivity to operating parameters.

Jay L. Hirshfield

2011-12-19

185

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

SciTech Connect

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

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

2011-10-20

186

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

NASA Astrophysics Data System (ADS)

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

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

1998-01-01

187

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

PubMed

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

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

2013-01-16

188

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

PubMed Central

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

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

2013-01-01

189

High efficiency protein separation with organosilane assembled silica coated magnetic nanoparticles  

Microsoft Academic Search

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

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

2008-01-01

190

Magnetic and fluorescence-encoded polystyrene microparticles for cell separation  

Microsoft Academic Search

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

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

2008-01-01

191

High-Gradient High-Energy-Gain Inverse Free Electron Laser Experiment Using a Helical Undulator  

SciTech Connect

In this paper we present the design of the high-gradient, high-energy-gain IFEL accelerator proposed for construction at the ATF beamline in BNL. We plan to accelerate the ATF electron beam from 50 MeV to 120 MeV using a 60 cm long tapered permanent magnet helical undulator designed at UCLA and the existing ATF 0.5 TW CO2 laser system. The experiment will obtain a record 120 MV/m gradient and >70 MeV energy gain and will be an important step in the development of compact IFEL accelerators for the mid-high energy range (up to 1-2 GeV).

Musumeci, P.; Westfall, M.; Li, R. K. [Department of Physics and Astronomy, University of California Los Angeles, Los Angeles, California, 90095 (United States); Murokh, A.; Tremaine, A. [Radiabeam Technologies LLC, Santa Monica, CA (United States); Pogorelsky, I. V. [Brookhaven National Laboratory, Upton, NY 11973 (United States)

2010-11-04

192

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

NASA Astrophysics Data System (ADS)

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

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

2011-11-01

193

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

PubMed

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

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

1978-06-01

194

An update on the study of high-gradient elliptical SRF cavities at 805 MHz for proton and other applications  

SciTech Connect

An update on the study of 805 MHz elliptical SRF cavities that have been optimized for high gradient will be presented. An optimized cell shape, which is still appropriate for easy high pressure water rinsing, has been designed with the ratios of peak magnetic and electric fields to accelerating gradient being 3.75 mT/(MV/m) and 1.82, respectively. A total of 3 single-cell cavities have been fabricated. Two of the 3 cavities have been tested so far. The second cavity achieved an E{sub acc} of {approx}50 MV/m at Q{sub 0} of 1.4 x 10{sup 10}. This result demonstrates that 805 MHz cavities can, in principle, achieve as high as, or could even be better than, 1.3 GHz high-gradient cavities.

Tajima, Tsuyoshi [Los Alamos National Laboratory; Haynes, Brian [Los Alamos National Laboratory; Krawczyk, Frank [Los Alamos National Laboratory; Madrid, Mike [Los Alamos National Laboratory; Roybal, Ray [Los Alamos National Laboratory; Simakov, Evgenya [Los Alamos National Laboratory; Clemens, Bob [TJNAF; Macha, Jurt [TJNAF; Manus, Bob [TJNAF; Rimmer, Bob [TJNAF; Rimmer, Bob [TJNAF; Turlington, Larry [TJNAF

2010-09-09

195

Characterization of flow resistance in high-gradient, forested streams  

NASA Astrophysics Data System (ADS)

Velocity and flow resistance of high-gradient, forested stream reaches in the Fraser Experimental Forest, Colorado, were characterized using Rhodamine WT dye tracing, ground-based LiDAR scans and laser theodolite surveying. Travel time and average reach velocities were computed using a spatial harmonic mean travel time, and compared to values computed using time between peaks and time between centroids. Peak velocities differed from harmonic by an average of 12.4 percent while centroid velocities differed by -2.8 percent. Manning’s n and Darcy-Weisbach ff were computed and related to numerous potential explanatory variables. Variables that quantified bed variability, such as the relative ratio of average maximum depth to standard deviation of the residuals of the bed profile regression, were the best predictors of flow resistance in these cascade, step-pool, plane-bed streams. Individual bed variability parameters explained 72 to 80 percent of the variance in the resistance coefficients. Spatial characterization of the resistance elements in relation to the resistance coefficients was also performed.

Yochum, S. E.; Bledsoe, B.; David, G. C.; Wohl, E. E.

2009-12-01

196

High-Gradient Photonic Bandgap (PBG) Accelerator Structure Breakdown Testing  

NASA Astrophysics Data System (ADS)

Photonic bandagp (PBG) accelerator structures provide unique insight into the surface physics involved in vacuum breakdown in accelerator structures because of their unique surface E and H fields. Peak operating gradients in accelerator structures are limited by surface breakdowns. These breakdowns occur at regions of high surface E and H fields. The maximum surface H field can easily be varied relative to the peak surface E field and accelerating gradient in PBG structures, allowing new regimes of parameter space to be explored. A standing wave PBG structure utilizing elliptical rods at the highest field locations has been tested at SLAC to determine the breakdown properties of the structure under high-gradient operation. The structure achieved a maximum gradient of approximately 125 MV/m at a breakdown probability of 3.6 *10-3 per pulse per meter for 150 ns pulses. This performance is comparable to conventional disc-loaded waveguide accelerator structures, but in a structure that provides intrinsic damping of wakefields.

Munroe, Brian; Shapiro, Michael; Temkin, Richard; Marsh, Roark; Dolgashev, Valery; Tantawi, Sami; Yeremian, Anahid

2012-10-01

197

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

National Technical Information Service (NTIS)

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

P. Liu D. Wang

1987-01-01

198

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...

199

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

PubMed

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

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

2005-02-23

200

Quantifying of magnetically separated particles using Hall-effect sensing  

NASA Astrophysics Data System (ADS)

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

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

2007-08-01

201

Electric charge separation in strong transient magnetic fields  

SciTech Connect

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

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

2010-06-15

202

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

Microsoft Academic Search

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

Keqing Li; Ming Zhu; Wen Ni; Baoshun Liu

2011-01-01

203

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

SciTech Connect

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

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

1987-11-01

204

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

PubMed

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

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

2012-07-06

205

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

Microsoft Academic Search

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

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

2011-01-01

206

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

Microsoft Academic Search

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

Richard Dixon Worley

1963-01-01

207

SECONDARY ELECTRON TRAJECTORIES IN HIGH-GRADIENT VACUUM INSULATORS WITH FAST HIGH-VOLTAGE PULSES  

SciTech Connect

Vacuum insulators composed of alternating layers of metal and dielectric, known as high-gradient insulators (HGIs), have been shown to withstand higher electric fields than conventional insulators. Primary or secondary electrons (emitted from the insulator surface) can be deflected by magnetic fields from external sources, the high-current electron beam, the conduction current in the transmission line, or the displacement current in the insulator. These electrons are deflected either toward or away from the insulator surface and this affects the performance of the vacuum insulator. This paper shows the effects of displacement current from short voltage pulses on the performance of high gradient insulators. Generally, vacuum insulator failure is due to surface flashover, initiated by electrons emitted from a triple junction. These electrons strike the insulator surface thus producing secondary electrons, and can lead to a subsequent electron cascade along the surface. The displacement current in the insulator can deflect electrons either toward or away from the insulator surface, and affects the performance of the vacuum insulator when the insulator is subjected to a fast high-voltage pulse. Vacuum insulators composed of alternating layers of metal and dielectric, known as high-gradient insulators (HGIs), have been shown to withstand higher electric fields than conventional insulators. HGIs, being tolerant of the direct view of high-current electron and ion beams, and having desirable RF properties for accelerators, are a key enabling technology for the dielectric-wall accelerators (DWA) being developed at Lawrence Livermore National Laboratory (LLNL). Characteristically, insulator surface breakdown thresholds go up as the applied voltage pulse width decreases. To attain the highest accelerating gradient in the DWA, short accelerating voltage pulses are only applied locally, along the HGI accelerator tube, in sync with the charged particle bunch, and the effects of displacement current on trajectories of electrons emitted from HGI surface are particularly interesting. This paper presents simulated electron trajectories experiencing either constant or short-duration applied voltage pulses. Comparisons of these trajectories clearly indicate the importance of the voltage pulse shape, especially the rise time, in the flashover initiation process for HGIs.

Chen, Y; Blackfield, D; Nelson, S D; Poole, B

2010-04-21

208

High-gradient two-beam accelerator structure  

NASA Astrophysics Data System (ADS)

A novel cavity structure is described that could be the basis for a two-beam, high-gradient, accelerator. Versions of the structure could be used for acceleration of beams of electrons, positrons, muons, protons, or heavier ions; with either electron or proton drive beams. The structure embodies cavities that are excited in several harmonically related eigenmodes, such that rf fields reach their peak values only during small portions of each basic rf period. This feature could help raise breakdown and pulse heating thresholds. The two-beam accelerator structure comprises chains of these cavities. In this configuration, no transfer elements are needed to couple rf energy from the drive beam to the accelerated beam, since both beams traverse the same cavities. Purposeful cavity detuning is used to provide much smaller deceleration for a high-current drive beam, than acceleration for a low-current accelerated beam, i.e., to provide a high transformer ratio. A self-consistent theory is presented to calculate idealized acceleration gradient, transformer ratio, and efficiency for energy transfer from the drive beam to the accelerated beam, for either parallel or antiparallel motion of the beams. The theory has been cast in dimensionless quantities so as to facilitate optimization with respect to efficiency, acceleration gradient, or transformer ratio, and to illuminate the interdependence of these parameters. Means for dramatically shortening the structure fill time are also described. However, no beam dynamics analysis is presented, so the range of parameters within which this new acceleration concept can be used will remain uncertain until it is established that stable beam transport along the structure using an appropriate focusing system is possible.

Kazakov, S. Yu; Kuzikov, S. V.; Jiang, Y.; Hirshfield, J. L.

2010-07-01

209

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

Microsoft Academic Search

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

A. Nakano; M. Shiraishi

2004-01-01

210

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

SciTech Connect

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

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

2010-08-20

211

Selective separation of proteins with pH-dependent magnetic nanoadsorbents  

NASA Astrophysics Data System (ADS)

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

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

2007-09-01

212

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

PubMed Central

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

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

2010-01-01

213

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

NASA Astrophysics Data System (ADS)

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

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

2010-03-01

214

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

PubMed

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

Kim, Byung I

2009-02-01

215

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

NASA Astrophysics Data System (ADS)

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

Rusin, Tomasz M.; Zawadzki, Wlodek

2012-08-01

216

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

SciTech Connect

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

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

1995-05-01

217

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

Microsoft Academic Search

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

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

2006-01-01

218

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

Microsoft Academic Search

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

Dong-Hwang Chen; Shih-Hung Huang

2004-01-01

219

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

Microsoft Academic Search

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

Feng Chen; Yinde Xie; Jincai Zhao; Gongxuan Lu

2001-01-01

220

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

PubMed

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

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

2013-10-15

221

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

NASA Astrophysics Data System (ADS)

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

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

2005-07-01

222

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

PubMed

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

Wang, Chungang; Irudayaraj, Joseph

2010-01-01

223

New High Performance Magnet Structures for Bead Based MolecularSeparation  

SciTech Connect

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

Humphries, David

2005-06-01

224

Fundamental study of cesium decontamination from soil by superconducting magnet  

NASA Astrophysics Data System (ADS)

The radioactive substances have been spread out all over the surrounding area of Fukushima Daiichi Nuclear Power Plant caused by the accident in March 2011. Decontamination and volume reduction of radioactive substances, especially cesium ion, are desired issue. This study proposed a decontamination method of the soil by the magnetic separation using superconducting magnet. Cesium ion was adsorbed by Prussian blue in the potassium iodide solution. We succeeded in separating selectively the cesium ion-adsorbed Prussian blue out of the liquid phase by high gradient magnetic separation. High recovery ratio of the Prussian blue was achieved by this method.

Igarashi, Susumu; Mishima, Fumihito; Akiyama, Yoko; Nishijima, Shigehiro

2013-11-01

225

Latest Results of ILC High-Gradient R&D 9-cell Cavities at JLAB  

SciTech Connect

It has been over a year since JLAB started processing and testing ILC 9-cell cavities in the frame work of ILC high-gradient cavity R&D, aiming at the goal of a 35 MV/m gradient at a Q #4; of 1E10 with a yield of 90%. The necessary cavity processing steps include field flatness tuning, electropolishing (EP), hydrogen out-gassing under vacuum, high-pressure water rinsing, clean room assembly, and low temperature bake. These are followed by RF test at 2 Kelvin. Ultrasonic cleaning with Micro-90, an effective post-EP rinsing recipe discovered at JLAB, is routinely used. Seven industry manufactured 9-cell TESLAshape cavities are processed and tested repeatedly. So far, 33 EP cycles are accumulated, corresponding to more than 65 hours of active EP time. An emphasis put on RF testing is to discern cavity quench characteristics, including its nature and its location. Often times, the cavity performance is limited by thermal-magnetic quench instead of field emission. The quench field in some cavities is lower than 20 MV/m and remains unchanged despite repeated EP, implying material and/or fabrication defects. The quench field in some other cavities is high but changes unpredictably after repeated EP, suggesting processing induced defects. Based on our experience and results, several areas are identified where improvement is needed to improve cavity performance as well as yield.

Rongli Geng

2008-02-11

226

Thermal design of drift tubes for high-gradient linacs  

SciTech Connect

We designed high-intensity drift tube linacs at Los Alamos using copper drift tubes capable of very high duty-factor operation, limited only by beam-loss heating in the bore. The drift-tube bodies are cooled by a peripheral, full-length cooling jacket that effectively clamps the drift tube at the average coolant temperature and shields the samarium-cobalt quadrupole from excessive heating caused by rf dissipation. The bore tube is thick-walled copper that is split to provide a gap for thermal-expansion, beam-diagnostic instrumentation, and vacuum relief of the drift-tube body. The magnet pole pieces are isolated from the bore tube by a 0.2-mm thermal gap that is very effective in preventing beam-loss heating from degrading the magnet properties of the quadrupoles. We discuss thermal studies that explore the capabilities of this design concept. The design features of the quadrupoles include a technique for precision shimming using captive screws and guide slots. We also present results of tests on prototype quadrupole assemblies.

Liska, D.J.; Bultman, N.; Carlisle, L.O.

1986-01-01

227

High efficiency protein separation with organosilane assembled silica coated magnetic nanoparticles  

NASA Astrophysics Data System (ADS)

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

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

2008-10-01

228

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

NASA Astrophysics Data System (ADS)

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

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

2012-04-01

229

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

SciTech Connect

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

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

1998-06-01

230

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

PubMed

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

Giakisikli, Georgia; Anthemidis, Aristidis N

2013-04-29

231

Summary Report for Working Group on High Gradient & EM Structure Based Accelerators.  

NASA Astrophysics Data System (ADS)

This is the summary of presentations and discussions of the High Gradient and EM Structure Based Accelerators Working Group at the 2008 Advanced Accelerator Concepts Workshop. The working group mission statement and charge are described and presentations on different topics are summarized. The topics include investigations of high gradient limitations (experimental and theoretical), new ideas and achievements in development of acceleration structures, rf sources, components, materials for accelerator applications, and others.

Yakovlev, V.; Smirnova, E. I.

2009-01-01

232

M13 bacteriophage-activated superparamagnetic beads for affinity separation.  

PubMed

The growth of the biopharmaceutical industry has created a demand for new technologies for the purification of genetically engineered proteins.The efficiency of large-scale, high-gradient magnetic fishing could be improved if magnetic particles offering higher binding capacity and magnetization were available. This article describes several strategies for synthesizing microbeads that are composed of a M13 bacteriophage layer assembled on a superparamagnetic core. Chemical cross-linking of the pVIII proteins to a carboxyl-functionalized bead produces highly responsive superparamagnetic particles (SPM) with a side-on oriented, adherent virus monolayer. Also, the genetic manipulation of the pIII proteins with a His(6) peptide sequence allows reversible assembly of the bacteriophage on a nitrilotriacetic-acid-functionalized core in an end-on configuration. These phage-magnetic particles are successfully used to separate antibodies from high-protein concentration solutions in a single step with a >90% purity. The dense magnetic core of these particles makes them five times more responsive to magnetic fields than commercial materials composed of polymer-(iron oxide) composites and a monolayer of phage could produce a 1000 fold higher antibody binding capacity. These new bionanomaterials appear to be well-suited to large-scale high-gradient magnetic fishing separation and promise to be cost effective as a result of the self-assembling and self-replicating properties of genetically engineered M13 bacteriophage. PMID:22619210

Muzard, Julien; Platt, Mark; Lee, Gil U

2012-05-23

233

Lateral-driven continuous magnetophoretic separation of blood cells  

NASA Astrophysics Data System (ADS)

We present a method for the lateral-driven continuous magnetophoretic separation of red and white blood cells from peripheral whole blood, based on their native magnetic properties. The separation is achieved using a high-gradient magnetic field, caused by a ferromagnetic wire array inlaid on glass substrate. The wire array creates an even lateral magnetophoretic force on the whole area of the microchannel, improving the separation efficiency and throughput. When the flow rate and external magnetic flux were 20 ?l/h and 0.3 T, respectively, the microseparator continuously separated out 93.9% of red blood cells and 89.2% of white blood cells from the whole blood.

Jung, Jinhee; Han, Ki-Ho

2008-12-01

234

Data Collection for Dynamic Temperature Modeling in High-Gradient Mountain Streams  

NASA Astrophysics Data System (ADS)

Neilson [2006] published results from a study in the Virgin River, UT where a data collection methodology was developed to assist in modeling the separate effects of hyporheic and dead zones on heat and solute transport. This study was unique in that temperature and tracer data were collected in the main channel, hyporheic zone, and dead zones to help estimate parameters associated with a two zone modeling approach rather than previous one zone modeling approaches that lump the effects of hyporheic and dead zones (transient storage). Research on a small section of Curtis Creek, UT, USA, has begun to investigate whether the data collection methodology and modeling approach developed by Neilson in the Virgin River, a desert river system with sand/gravel substrate and relatively low average channel slopes, could be implemented in a mountain stream with gravel/cobble substrate and higher average channel slopes that are highly influenced by groundwater. Initial data suggested that instream temperatures in this small high-gradient steam are significantly affected by riparian shading, deep groundwater, surface groundwater seeps, hyporheic exchange, and bed conduction. Therefore, new data types were collected in the current study in order to begin to separate out some of the complex and confounded sources and sinks of heat found in mountain streams that need to be quantified for temperature model population and testing. These included riparian shading mapping, detailed channel surveys, groundwater observation wells, and an increased number of tracer tests to assist in quantifying groundwater influx through dilution studies. Additionally, new installation techniques had to be applied for equipment inserted in the bed sediments. Preliminary data, analyses, and installation techniques will be presented. Neilson, B. T. (2006), Dynamic Stream Temperature Modeling: Understanding the Causes and Effects of Temperature Impairments and Uncertainty in Predictions, Dissertation thesis, Utah State University, Logan, UT.

Neilson, B. T.; Schmadel, N.; Bingham, J. D.; Hobson, A. J.

2007-12-01

235

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

NASA Astrophysics Data System (ADS)

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

He, Yanjie; Li, Qiulin; Liu, Wei

2012-10-01

236

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

PubMed

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

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

2012-04-01

237

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

PubMed

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

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

2012-07-13

238

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

NASA Astrophysics Data System (ADS)

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

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

2012-07-01

239

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

PubMed

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

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

1992-01-01

240

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

SciTech Connect

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

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

1995-11-01

241

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

PubMed

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

Yeung, H N; Kormos, D W

1986-06-01

242

Bulk magnetization and nuclear magnetic resonance of magnetically purified layered silicates and their polymer-based nanocomposites  

NASA Astrophysics Data System (ADS)

The bulk magnetization and the 1H and 29Si nuclear-magnetic-resonance (NMR) spectra of two layered silicates, montmorillonite (MMT) and hectorite (HCT), purified by high-gradient magnetic separation, and of HCT-polymer nanocomposites have been measured. At 300 K, the magnetization of MMT as received shows a behavior typical of paramagnets and does not change significantly even after ~100 h of magnetic separation. The magnetization of HCT as received is typical of a weak ferromagnet but it changes drastically after magnetic separation. The extracted particles have sizes varying from a few to about 150 ?m and show ferromagneticlike properties at 300 K. While the magnetization/magnetic-field ratio, M/H, of HCT is reduced 50-fold after ~15 min of magnetic separation and shows predominantly diamagnetic properties at 300 K after ~30 h, we have also found that HCT contains ~0.2 mass % of paramagnetic Fe ions, with an effective magnetic moment of ~5.2?B per Fe ion, as a regular element of its lattice. This is much smaller than the ~3.8 mass % in MMT. Spinning sidebands in 1H NMR spectra of HCT as received are reduced by magnetic separation. This indicates that dipolar interactions between nuclei and paramagnetic ions even in separated phases can affect the NMR spectra. Magnetically purified hectorite was used for preparing polymer-HCT nanocomposites where the NMR spectra show increased signal-to-noise ratios.

Levin, E. M.; Rawal, A.; Bud'Ko, S. L.; Kracher, A.; Schmidt-Rohr, K.

2005-12-01

243

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

NASA Astrophysics Data System (ADS)

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

Ghebremeskel, Alazar N.; Bose, Arijit

2003-04-01

244

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

NASA Astrophysics Data System (ADS)

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

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

2010-04-01

245

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

PubMed

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

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

2013-07-10

246

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

Microsoft Academic Search

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

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

2007-01-01

247

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

Microsoft Academic Search

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

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

2006-01-01

248

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

Microsoft Academic Search

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

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

2011-01-01

249

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

PubMed

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

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

2013-08-27

250

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

PubMed

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

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

2012-03-13

251

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

NASA Astrophysics Data System (ADS)

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

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

2010-07-01

252

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

SciTech Connect

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

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

2000-11-01

253

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

PubMed

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

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

2011-04-09

254

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

PubMed

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

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

2011-05-17

255

Measured and theoretical characterization of the RF properties of stacked, high-gradient insulator material  

SciTech Connect

Recent high-voltage breakdown experiments of periodic metallic-dielectric insulating structures have suggested several interesting high-gradient applications. One such area is the employment of high-gradient insulators in high-current, electron-beam, accelerating induction modules. For this application, the understanding of the rf characteristics of the insulator plays an important role in estimating beam-cavity interactions. In this paper, we examine the rf properties of the insulator comparing simulation results with experiment. Different insulator designs are examined to determine their rf transmission properties in gap geometries.

Houck, T. L., LLNL

1997-05-09

256

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

SciTech Connect

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

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

2010-12-20

257

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

NASA Astrophysics Data System (ADS)

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

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

2012-12-01

258

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

NASA Astrophysics Data System (ADS)

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

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

2007-09-01

259

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

NASA Astrophysics Data System (ADS)

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

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

2012-05-01

260

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

NASA Astrophysics Data System (ADS)

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

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

2006-07-01

261

Design features of a seven-cell high-gradient superconducting cavity  

Microsoft Academic Search

A cavity development program is in place at Los Alamos National Laboratory to evaluate structures that could be used to accelerate pions. The work is being guided by the conceptual design of PILAC, a high-gradient superconducting linac for raising the energy of rapidly decaying intense pion beams generated by Los Alamos Meson Physics Facility (LAMPF) to 1 GeV. The specification

D. J. Liska; J. Ledford; S. Black; G. Spalek; J. N. Dimarco

1992-01-01

262

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

NASA Astrophysics Data System (ADS)

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

Song, Yu; Tao, Ling; Shen, Xiangchun

2012-07-01

263

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

PubMed Central

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

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

2009-01-01

264

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

DOEpatents

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

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

1999-07-20

265

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

DOEpatents

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

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

1999-01-01

266

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

NASA Astrophysics Data System (ADS)

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

Dupré, Luc; Sergeant, Peter; Vandenbossche, Lode

2005-05-01

267

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

PubMed

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

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

2013-03-13

268

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

PubMed

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

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

2012-08-07

269

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

NASA Astrophysics Data System (ADS)

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

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

2009-04-01

270

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

PubMed

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

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

2013-03-02

271

Experimental and theoretical investigation of high gradient acceleration. Progress report, February 1, 1992--January 31, 1993  

SciTech Connect

This report contains a technical progress summary of the research conducted under the auspices of DOE Grant No. DE-AC02-91-ER40648, ``Experimental and Theoretical Investigations of High Gradient Acceleration``. This grant supports three research tasks: Task A consists of the design, fabrication and testing of a 17GHz RF photocathode gun, which can produce 2ps electron pulses with up to 1nC of charge at 2MeV energy and at a 1OHz repetition rate. Task B supports the testing of high gradient acceleration at 33GHz structure, and Task C comprises theoretical investigations, both in support of the experimental tasks and on critical physics issues for the development of high energy linear colliders.

Wurtele, J.S.; Bekefi, G.; Chen, C.; Chen, S.C.; Temkin, R.J.

1993-01-01

272

Summary Report of Working Group 3: High Gradient and Laser-Structure Based Acceleration  

NASA Astrophysics Data System (ADS)

The charge for the working group on high gradient and laser-structure based acceleration was to assess the current challenges involved in developing an advanced accelerator based on electromagnetic structures, and survey state-of-the-art methods to address those challenges. The topics of more than 50 presentations in the working group covered a very broad range of issues, from ideas, theoretical models and simulations, to design and manufacturing of accelerating structures and, finally, experimental results on obtaining extremely high accelerating gradients in structures from conventional microwave frequency range up to THz and laser frequencies. Workshop discussion topics included advances in the understanding of the physics of breakdown and other phenomena, limiting high gradient performance of accelerating structures. New results presented in this workshop demonstrated significant progress in the fields of conventional vacuum structure-based acceleration, dielectric wakefield acceleration, and laser-structure acceleration.

Solyak, N.; Cowan, B. M.

2010-11-01

273

A Compact x-ray Radiography Accelerator Using High-Gradient Vacuum Insulator Technology  

Microsoft Academic Search

Using the high-gradient vacuum dielectric wall accelerator technology, the authors are developing a compact induction accelerator system primarily intended for pulsed X-ray radiography. The accelerator would provide a 2-kA beam for a 20-30 ns flat-top. The design goal is to generate a 2-mm diameter X-ray source. There are two physics designs of the system from the injector to the X-ray

Yu-Jiuan Chen; J. F. McCarrick; S. D. Nelson

2006-01-01

274

Fabrication Technologies of the High Gradient Accelerator Structures at 100MV\\/M Range  

Microsoft Academic Search

A CERN-SLAC-KEK collaboration on high gradient X-band structure research has been established in order to demonstrate the feasibility of the CLIC baseline design for the main linac stably operating at more than 100 MV\\/m loaded accelerating gradient. Several prototype CLIC structures were successfully fabricated and high power tested. They operated at 105 MV\\/m with a breakdown rate that meets the

2012-01-01

275

Study of Ka-band components for a future high-gradient linear accelerator  

Microsoft Academic Search

Efforts are underway within the accelerator community to develop high-gradient RF accelerators using microwave sources at relatively high frequencies (in particular, at 34.272 GHz). Yet no corresponding high-power components providing pulse compression, transmission and input coupling to the accelerating structure are currently available. Results of investigations of many components including resonator passive pulse compressor, controllable launcher for a DLDS system,

G. G. Denisov; A. G. Litavk; M. I. Petelin; A. L. Vikharev; S. V. Kuzikov; A. M. Gorbachev; V. G. Paveliev; A. A. Bogdashov; M. Yu. Shmelev; J. L. Hirshfield

2002-01-01

276

Technological Issues and High Gradient Test Results on X-Band Molybdenum Accelerating Structures  

SciTech Connect

Two 11.424 GHz single cell standing wave accelerating structures have been fabricated for high gradient RF breakdown studies. Both are brazed structures: one made from copper and the other from sintered molybdenum bulk. The tests results are presented and compared to those of similar devices constructed at SLAC (Stanford Linear Accelerator Center) and KEK (Ko Enerugi Kasokuki Kenkyu Kiko). The technological issues to build both sections are discussed.

Spataro, B.; /LNF, Dafne Light; Alesini, D.; /LNF, Dafne Light; Chimenti, V.; /LNF, Dafne Light; Dolgashev, V.; /SLAC; Haase, A.; /SLAC; Tantawi, S.G.; /SLAC; Higashi, Y.; /KEK, Tsukuba; Marrelli, C.; /Rome U.; Mostacci, A.; /Rome U.; Parodi, R.; /INFN, Genoa; Yeremian, A.D.; /SLAC

2012-04-24

277

HIGH GRADIENT DIELECTRIC WAKEFIELD DEVICE MEASUREMENTS AT THE ARGONNE WAKEFIELD ACCELERATOR  

Microsoft Academic Search

The Argonne Wakefield Accelerator (AWA) is a facility designed to investigate high gradient wakefield acceleration techniques. Wakefields are excited using a drive beam produced by a 14 MeV high current photoinjector-based linac. A second photocathode gun generates a 4 MeV witness beam which is used as a probe of the wakefields in the device under test. The delay of the

P. Schoessow; M. Conde; W. Gai; R. Konecny; J. Simpson

1998-01-01

278

Separation of semiconducting and ferromagnetic FeSi2-nanoparticles by magnetic filtering  

NASA Astrophysics Data System (ADS)

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

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

2013-10-01

279

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

NASA Astrophysics Data System (ADS)

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

Lazanja, David

2005-10-01

280

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

NASA Astrophysics Data System (ADS)

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

Terletska, Hanna; Dobrosavljevic, Vladimir

2010-11-01

281

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

NASA Astrophysics Data System (ADS)

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

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

2010-08-01

282

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

NASA Astrophysics Data System (ADS)

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

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

2012-12-01

283

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

Microsoft Academic Search

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

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

2008-01-01

284

Method and apparatus for fabrication of high gradient insulators with parallel surface conductors spaced less than one millimeter apart  

DOEpatents

Optical patterns and lithographic techniques are used as part of a process to embed parallel and evenly spaced conductors in the non-planar surfaces of an insulator to produce high gradient insulators. The approach extends the size that high gradient insulating structures can be fabricated as well as improves the performance of those insulators by reducing the scale of the alternating parallel lines of insulator and conductor along the surface. This fabrication approach also substantially decreases the cost required to produce high gradient insulators.

Sanders, David M. (Livermore, CA); Decker, Derek E. (Livermore, CA)

1999-01-01

285

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

NASA Astrophysics Data System (ADS)

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

Harrison, Neil

2010-03-01

286

High-gradient operators in perturbed Wess-Zumino-Witten field theories in two dimensions  

NASA Astrophysics Data System (ADS)

Many classes of non-linear sigma models (NL?Ms) are known to contain composite operators with an arbitrary number 2s of derivatives (“high-gradient operators”) which appear to become strongly relevant within renormalization group (RG) calculations at one (or fixed higher) loop order, when the number 2s of derivatives becomes large. This occurs at many conventional fixed points of NL?Ms which are perturbatively accessible within the usual ?-expansion in d=2+? dimensions. Since such operators are not prohibited from occurring in the action, they appear to threaten the very existence of such fixed points. At the same time, for NL?Ms describing metal-insulator transitions of Anderson localization in electronic conductors, the strong RG-relevance of these operators has been previously related to statistical properties of the conductance of samples of large finite size (“conductance fluctuations”). In this paper, we analyze this question, not for perturbative RG treatments of NL?Ms, but for two-dimensional Wess-Zumino-Witten (WZW) models at level k, perturbatively in the current-current interaction of the Noether current (“non-Abelian Thirring/Gross-Neveu models”). WZW models are special (“Principal Chiral”) NL?Ms on a Lie Group G with a WZW term at level k. In these models the role of high-gradient operators is played by homogeneous polynomials of order 2s in the Noether currents, whose scaling dimensions we analyze. For the Lie Supergroup G=GL(2N|2N) and k=1, this corresponds to time-reversal invariant problems of Anderson localization in the so-called chiral symmetry classes, and the strength of the current-current interaction, a measure of the strength of disorder, is known to be completely marginal (for any k). We find that all high-gradient (polynomial) operators are, to one loop order, irrelevant or relevant depending on the sign of that interaction.

Ryu, S.; Mudry, C.; Ludwig, A. W. W.; Furusaki, A.

2010-11-01

287

Multi-MW K-Band 7th Harmonic Multiplier for High-Gradient Accelerator R&D  

SciTech Connect

A preliminary design and current status are presented for a two-cavity 7th harmonic multiplier, intended as a high-power RF source for use in experiments aimed at developing high-gradient structures for a future collider. The harmonic multiplier is to produce power in K-band using as its RF driver an XK-5 S-band klystron (2.856 GHz). The multiplier is to be built with a TE{sub 111} rotating mode input cavity and interchangeable output cavities, a principal example being a TE{sub 711} rotating mode cavity running at 20 GHz. The design that is described uses a 250 kV, 20 A injected laminar electron beam. With 8.5 MW of S-band drive power, 4.4 MW of 20-GHz output power is predicted. The design uses a gun, magnetic coils, and beam collector from an existing waveguide 7th harmonic multiplier. The gun has been re-conditioned and the desired operating parameters have been achieved.

Solyak, N.A.; Yakovlev, V.P.; /Omega-P, New Haven /Fermilab; Hirschfield, J.L.; /Omega-P, New Haven /Yale U.; Kazakevich, G.M.; /Omega-P, New Haven; LaPointe, M.A.; /Yale U.

2009-05-01

288

Multi-MW K-Band Harmonic Multiplier: RF Source For High-Gradient Accelerator R & D  

NASA Astrophysics Data System (ADS)

A preliminary design is presented for a two-cavity harmonic multiplier, intended as a high-power RF source for use in experiments aimed at developing high-gradient structures for a future collider. The harmonic multiplier is to produce power at selected frequencies in K-band (18-26.5 GHz) using as an RF driver an XK-5 S-band klystron (2.856 GHz). The device is to be built with a TE111 rotating mode input cavity and interchangeable output cavities running in the TEn11 rotating mode, with n = 7,8,9 at 19.992, 22.848, and 25.704 GHz. An example for a 7th harmonic multiplier is described, using a 250 kV, 20 A injected laminar electron beam; with 10 MW of S-band drive power, 4.7 MW of 20-GHz output power is predicted. Details are described of the magnetic circuit, cavities, and output coupler.

Solyak, N. A.; Yakovlev, V. P.; Kazakov, S. Yu.; Hirshfield, J. L.

2009-01-01

289

Multi-MW K-Band Harmonic Multiplier: RF Source For High-Gradient Accelerator R and D  

SciTech Connect

A preliminary design is presented for a two-cavity harmonic multiplier, intended as a high-power RF source for use in experiments aimed at developing high-gradient structures for a future collider. The harmonic multiplier is to produce power at selected frequencies in K-band (18-26.5 GHz) using as an RF driver an XK-5 S-band klystron (2.856 GHz). The device is to be built with a TE{sub 111} rotating mode input cavity and interchangeable output cavities running in the TE{sub n11} rotating mode, with n = 7,8,9 at 19.992, 22.848, and 25.704 GHz. An example for a 7{sup th} harmonic multiplier is described, using a 250 kV, 20 A injected laminar electron beam; with 10 MW of S-band drive power, 4.7 MW of 20-GHz output power is predicted. Details are described of the magnetic circuit, cavities, and output coupler.

Solyak, N. A.; Yakovlev, V. P. [Omega-P, Inc., 199 Whitney Ave., New Haven, CT 06511 (United States); Fermi National Accelerator Laboratory, Batavia, IL 60510 (United States); Kazakov, S. Yu. [Omega-P, Inc., 199 Whitney Ave., New Haven, CT 06511 (United States); High Energy Accelerator Research Organization, KEK, Tsukuba, Ibaraki 305-0801 Japan (Japan); Hirshfield, J. L. [Omega-P, Inc., 199 Whitney Ave., New Haven, CT 06511 (United States); Beam Physics Laboratory, Yale University, 272 Whitney Avenue, New Haven, CT 06511 (United States)

2009-01-22

290

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

PubMed

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

Furlan, Marco; Lattuada, Marco

2012-08-14

291

SRF Cavity High-Gradient Study at 805 MHz for Proton and Other Applications  

SciTech Connect

805 MHz elliptical SRF cavities have been used for SNS as the first application for protons. At LANL, an R&D started to explore a capability of getting high-gradient cavities (40-50 MV/m) at this frequency for the future applications such as proton and muon based interrogation testing facility added to the LANSCE accelerator and a power upgrade of the LANSCE accelerator for the fission and fusion material test station. Optimized cell designs for “standard”, “low-loss” and “re-entrant” shapes, cavity test results for “standard” single-cell cavities with temperature mapping as well as surface inspection results will be presented.

Tajima, T; Chacon, P; Edwards, R L; Eremeev, G V; Krawczyk, F L; Roybal, R J; Sedillo, J D; Clemens, W A; Kneisel, P; Manus, R; Rimmer, R A

2009-05-01

292

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

NASA Astrophysics Data System (ADS)

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

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

1995-07-01

293

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

PubMed Central

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

2013-01-01

294

Large-scale superconducting separator for Kaolin processing  

SciTech Connect

Currently, high gradient magnetic separators (HGMSs) are used almost exclusively by the clay processing industry, particularly in producing an extremely white kaolin for the paper, coatings and rubber industries where a bright additive is desirable. As mined, the clay is a light cream color-not white. Many of these impurities can be removed chemically using a reducing agent such as sodium hydrosulfite in low pH, sulfuric acid, and alum. High purity, however, can be obtained by removing trace amounts of paramagnetic particles (100% finer than 2 {mu}m). This is accomplished by separating these particles from 28 wt% kaolin in a water slurry retaining them on magnetic wool, which is then periodically regenerated.

Winters, A.J, Jr. (Cryogenic Consultants, Inc. Allentown, PA (US)); Selvaggi, J.A. (Eriez Magnetics, Erie, PA (US))

1990-01-01

295

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...

296

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

Microsoft Academic Search

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

Chungang Wang; Joseph Irudayaraj

2010-01-01

297

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

PubMed

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

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

2013-03-08

298

High gradient dielectric wakefield device measurements at the Argonne wakefield accelerator  

SciTech Connect

The Argonne Wakefield Accelerator (AWA) is a facility designed to investigate high gradient wakefield acceleration techniques. Wakefields are excited using a drive beam produced by a 14 MeV high current photoinjector-based linac. A second photocathode gun generates a 4 MeV witness beam which is used as a probe of the wakefields in the device under test. The delay of the witness bunch with respect to the drive bunch can be continuously varied from -100 ps to >1 ns. The drive and witness bunches propagate along collinear or parallel trajectories through the test section. A dipole spectrometer is then used to measure the energy change of the witness beam. The complete wakefield measurement system has been commissioned and wakefield experiments using dielectric structures are underway. Initial experiments have focused on collinear wakefield device geometries where the drive and witness bunches traverse the same structure. For attaining very high gradients we will construct and study step-up transformer structures in which the rf pulse generated by the drive beam is compressed transversely and longitudinally.

Schoessow, P.; Conde, M.; Gai, W.; Konecny, R.; Power, J.; Simpson, J.

1997-10-01

299

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

PubMed

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

Piao, Chunying; Chen, Ligang

2012-10-26

300

Magnetic Structure and Phase Separation in Epitaxial SrCoOx Thin Films  

NASA Astrophysics Data System (ADS)

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

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

2013-03-01

301

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

NASA Astrophysics Data System (ADS)

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

Kapcia, Konrad; Robaszkiewicz, Stanis?aw

2013-02-01

302

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

PubMed

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

Kapcia, Konrad; Robaszkiewicz, Stanis?aw

2013-02-13

303

Relativistic klystron driven compact high gradient accelerator as an injector to an X-ray synchrotron radiation ring  

DOEpatents

A compact high gradient accelerator driven by a relativistic klystron is utilized to inject high energy electrons into an X-ray synchrotron radiation ring. The high gradients provided by the relativistic klystron enables accelerator structure to be much shorter (typically 3 meters) than conventional injectors. This in turn enables manufacturers which utilize high energy, high intensity X-rays to produce various devices, such as computer chips, to do so on a cost effective basis.

Yu, David U. L. (1912 MacArthur St., Rancho Palos Verdes, CA 90732)

1990-01-01

304

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

NASA Astrophysics Data System (ADS)

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

Mayo, John Thomas

305

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

SciTech Connect

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

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

1995-07-01

306

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

PubMed

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

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

2013-05-01

307

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

PubMed

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

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

2007-07-13

308

Transverse wakefield suppression using cell detuning assisted by manifold damping for high gradient linear colliders  

NASA Astrophysics Data System (ADS)

Transverse wakefields excited by multiple bunches in ultra-relativistic charged particle beams in a linear collider must be adequately damped in order to preserve the luminosity of the colliding beams and to prevent a beam break up instability developing. Means of achieving this wakefield suppression are discussed in detail for high gradient normal conducting linacs. In particular the features of a damped and detuned series of structures (DDS) are described. Analytical expressions for the wakefield on short time scales are presented together with the circuit analysis required to rapidly analyse the general long-range behaviour in these linacs. A conspectus of experimental results along with theoretical predictions for this series of accelerating structures developed for the NLC/GLC is presented together with recent results on wakefield suppression for CLIC.

Jones, Roger M.

2011-11-01

309

An Ultra-High Gradient Cherenkov Wakefield Acceleration Experiment at SLAC FFTB  

SciTech Connect

The creation of ultra-high current, ultra-short pulse beams Q=3 nC, {sigma}{sub z} = 20{micro}m at the SLAC FFTB has opened the way for very high gradient plasma wakefield acceleration experiments. We study here the use of these beams in a proposed Cherenkov wakefield experiment, where one may excite electromagnetic wakes in a simple dielectric tube with inner diameter of few 100 microns that exceed the GV/m level. We discuss the scaling of the fields with design geometric design parameters, and choice of dielectric. We also examine measurable aspects of the experiment, such as the total coherent Cerenkov radiation energy one may collect, and the expected aspects of dielectric breakdown at high fields.

Rosenzweig, J.B.; Hoover, S.; Hogan, M.J.; Muggli, P.; Thompson, M.; Travish, G.; Yoder, R.; /UCLA /SLAC /Southern California U.

2005-08-02

310

Ultra-High Gradient Compact S-Band Linac for Laboratory and Industrial Applications  

SciTech Connect

There is growing demand from the industrial and research communities for high gradient, compact RF accelerating structures. The commonly used S-band SLAC-type structure has an operating gradient of only about 20 MV/m; while much higher operating gradients (up to 70 MV/m) have been recently achieved in X-band, as a consequence of the substantial efforts by the Next Linear Collider (NLC) collaboration to push the performance envelope of RF structures towards higher accelerating gradients. Currently however, high power X-band RF sources are not readily available for industrial applications. Therefore, RadiaBeam Technologies is developing a short, standing wave S-band structure which uses frequency scaled NLC design concepts to achieve up to a 50 MV/m operating gradient at 2856 MHz. The design and prototype commissioning plans are presented.

Faillace, Luigi; /RadiaBeam Tech.; Agustsson, Ronald; /RadiaBeam Tech.; Frigola, Pedro; /RadiaBeam Tech.; Murokh, Alex; /RadiaBeam Tech.; Dolgashev, Valery; /SLAC; Rosenzweig, James; /UCLA

2012-07-03

311

Progress of ILC High Gradient SRF Cavity R&D at Jefferson Lab  

SciTech Connect

Latest progress of ILC high gradient SRF cavity R&D at Jefferson Lab will be presented. 9 out of 10 real 9-cell cavities reached an accelerating gradient of more than 38 MV/m at a unloaded quality factor of more than 8 {center_dot} 109. New understandings of quench limitation in 9-cell cavities are obtained through instrumented studies of cavities at cryogenic temperatures. Our data have shown that present limit reached in 9-cell cavities is predominantly due to localized defects, suggesting that the fundamental material limit of niobium is not yet reached in 9-cell cavities and further gradient improvement is still possible. Some examples of quench-causing defects will be given. Possible solutions to pushing toward the fundamental limit will be described.

R.L. Geng, J. Dai, G.V. Eremeev, A.D. Palczewski

2011-09-01

312

Dense Plasma Focus Z-pinches for High Gradient Particle Acceleration  

SciTech Connect

The final Z-pinch stage of a Dense Plasma Focus (DPF) could be used as a simple, compact, and potentially rugged plasma-based high-gradient accelerator with fields at the 100 MV/m level. In this paper we review previously published experimental beam data that indicate the feasibility of such an DPF-based accelerator, qualitatively discuss the physical acceleration processes in terms of the induced voltages, and as a starting point examine the DPF acceleration potential by numerically applying a self-consistent DPF system model that includes the induced voltage from both macroscopic and instability driven plasma dynamics. Applications to the remote detection of high explosives and a multi-staged acceleration concept are briefly discussed.

Tang, V; Adams, M L; Rusnak, B

2009-07-24

313

Ion Solid Interaction And Surface Modification At RF Breakdown In High-Gradient Linacs  

SciTech Connect

Ion solid interactions have been shown to be an important new mechanism of unipolar arc formation in high-gradient rf linear accelerators through surface self-sputtering by plasma ions, in addition to an intense surface field evaporation. We believe a non-Debye plasma is formed in close vicinity to the surface and strongly affects surface atomic migration via intense bombardment by ions, strong electric field, and high surface temperature. Scanning electron microscope studies of copper surface of an rf cavity were conducted that show craters, arc pits, and both irregular and regular ripple structures with a characteristic length of 2 microns on the surface. Strong field enhancements are characteristic of the edges, corners, and crack systems at surfaces subjected to rf breakdown.

Insepov, Zeke; Norem, Jim [Argonne National Laboratory, 9700 South Cass Avenue, Argonne, IL 60439 (United States); Veitzer, Seth [Tech-X Corp., 5621 Arapahoe Ave., Suite A, Boulder CO 80303 (United States)

2011-06-01

314

Studies of Breakdown in High Gradient X-Band Accelerator Structures Using Acoustic Emission  

NASA Astrophysics Data System (ADS)

X-band accelerator structures meeting the Next Linear Collider (NLC) design requirements have been found to suffer damage due to RF breakdown when processed to high gradients. Improved understanding of these breakdown events is desirable for the development of structure designs, fabrication procedures, and processing techniques that minimize structure damage. Acoustic emission sensors attached to an accelerator structure can detect both nominal and breakdown RF pulses. Using an array of acoustic sensors, we have been able to pinpoint both the cell and azimuth location of individual breakdown events. This allows studies of breakdown time and position sequences so that underlying causes can be determined. The technique provided a significant advance in studies of breakdown in the structure input coupler. In this paper we present acoustic emission sensor data and analysis from the breakdown studies in several x-band accelerator structures.

Frisch, J.; Nelson, J.; Le Pimpec, F.; Jobe, K.; McCormick, D.

2002-08-01

315

A High-Gradient CW R Photo-Cathode Electron Gun for High Current Injectors  

SciTech Connect

The paper describes the analysis and preliminary design of a high-gradient photo-cathode RF gun optimized for high current CW operation. The gun cell shape is optimized to provide maximum acceleration for the newly emitted beam while minimizing wall losses in the structure. The design is intended for use in future high-current high-power CW FELs but the shape optimization for low wall losses may be advantageous for other applications such as XFELs or Linear Colliders using high peak power low duty factor guns where pulse heating is a limitation. The concept allows for DC bias on the photocathode in order to repel ions and improve cathode lifetime.

Robert Rimmer

2005-05-01

316

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

PubMed

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

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

2006-10-05

317

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

Microsoft Academic Search

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

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

318

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

PubMed

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

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

1981-01-01

319

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

PubMed

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

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

2013-10-01

320

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

PubMed

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

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

2011-08-22

321

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

NASA Astrophysics Data System (ADS)

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

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

2011-08-01

322

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

NASA Astrophysics Data System (ADS)

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

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

2013-09-01

323

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

NASA Astrophysics Data System (ADS)

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

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

2008-03-01

324

A 3 T magnetic field generator using melt-processed bulk superconductors as trapped field magnets and its applications  

NASA Astrophysics Data System (ADS)

An intense magnetic field generator yielding 3.15 T in the open space between the magnetic poles has been constructed by using a pair of melt-processed bulk superconductors as trapped field magnets. The field was measured in a 2 mm gap between the magnetic poles set face-to-face after the pulsed-field magnetization ``IMRA'' method. This field generator is composed of Sm-based 123 compounds, vacuum pumps, pulsed-field coils and GM refrigerators with compressors. The system can be used in various applications. We investigated, for instance, the application to a high gradient magnetic separation system. It was found that the alpha hematite fine particles mixed in the flowing water was completely removed by this technique which was operated in the field of 1.7 T in the gap of 20 mm.

Oka, T.; Yokoyama, K.; Itoh, Y.; Yanagi, Y.; Yoshikawa, M.; Ikuta, H.; Mizutani, U.; Okada, H.; Noto, K.

2003-10-01

325

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

Microsoft Academic Search

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

S. Murad

2006-01-01

326

Preliminary Results from the UCLA/SLAC Ultra-High Gradient CerenkovWakefield Accelerator Experiment  

SciTech Connect

The first phase of an experiment to study the performance of dielectric Cerenkov wakefield accelerating structures at extremely high gradients in the GV/m range has been completed. This experiment takes advantage of the unique SLAC FFTB electron beam and its demonstrated ultra-short pulse lengths and high currents (e.g., {sigma}{sub z} = 20 {micro}m at Q = 3 nC). The FFTB electron beam has been successfully focused down and sent through varying lengths of fused silica capillary tubing with two different sizes: ID = 200 {micro}m/OD = 325 {micro}m and ID = 100 {micro}m/OD = 325 {micro}m. The pulse length of the electron beam was varied in the range 20 {micro}m < {sigma}{sub z} < 100 {micro}m which produced a range of electric fields between 2 and 20 GV/m at the inner surface of the dielectric tubes. We observed a sharp increase in optical emissions from the capillaries in the middle part of this surface field range which we believe indicates the transition between sustainable field levels and breakdown. If this initial interpretation is correct, the surfaced fields that were sustained equate to on axis accelerating field of several GV/m. In future experiments we plan to collect and measure coherent Cerenkov radiation emitted from the capillary tube to gain more information about the strength of the accelerating fields.

Thompson, M.C.; Badakov, H.; Rosenzweig, J.B.; Travish, G.; /UCLA; Hogan, M.; Ischebeck, R.; Kirby, N.; Siemann, R.; Walz, D.; /SLAC; Muggli, P.; /Southern California U.; Scott, A.; /UC, Santa Barbara; Yoder, R.; /Manhattan Coll., Riverdale

2008-02-06

327

The UCLA/SLAC Ultra-High Gradient Cerenkov Wakefield Accelerator Experiment  

SciTech Connect

An experiment is planned to study the performance of dielectric Cerenkov wakefield accelerating structures at extremely high gradients in the GV/m range. This new UCLA/SLAC/USC collaboration will take advantage of the unique SLAC FFTB electron beam and its demonstrated ultra-short pulse lengths and high currents (e.g., {delta}{sub z} = 20 {micro}m at Q = 3 nC). The electron beam will be focused down and sent through varying lengths of fused silica capillary tubing with two different sizes: ID = 200 {micro}m/OD = 325 {micro}m and ID = 100 {micro}m/OD = 325 {micro}m. The pulse length of the electron beam will be varied in order to alter the accelerating gradient and probe the breakdown threshold of the dielectric structures. In addition to breakdown studies, we plan to collect and measure coherent Cerenkov radiation emitted from the capillary tube to gain information about the strength of the accelerating fields.

Thompson, M.C.; Badakov, H.; Rosenzweig, J.B.; Travish, G.; /UCLA; Hogan, M.; Ischebec, R.; Siemann, R.; Walz, D.; /SLAC; Scott, A.; /UC, Santa Barbara; Yoder, R.; /Manhattan Coll., Riverdale

2006-01-25

328

On a plasma sheath separating regions of oppositely directed magnetic field  

Microsoft Academic Search

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

E. G. Harris

1962-01-01

329

Magnetic flocculation and filtration  

SciTech Connect

A model is available in predicting flocculation frequencies between particles of various properties under the influence of a magnetic field. This model provides a basic understanding of fundamental phenomena, such as particle-particle and particle-collector interactions, occurring in HGMF (high gradient magnetic field), and will be extended to describe experimental data of particle flocculation and filtration and predict the performance of high- gradient magnetic filters. It is also expected that this model will eventually lead to a tool for design and optimization of magnetic filters for environmental, metallurgical, biochemical, and other applications.

Yiacoumi, Sotira; Chin, Ching-Ju; Yin, Tung-Yu [Georgia Inst. of Tech., Atlanta, GA (United States). School of Civil and Environmental Engineering; Tsouris, C., DePaoli, D.W.; Chattin, M.R.; Spurrier, M. [Oak Ridge National Lab., TN (United States)

1996-10-01

330

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

PubMed

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

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

2013-09-30

331

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

PubMed Central

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

Yan, Xiaoyan; Gilman, S. Douglass

2010-01-01

332

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

SciTech Connect

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

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

2004-08-02

333

Numerical Study of High Gradient Thermobuoyant Flow in a Tilted Cavity Using a Novel Non-Boussinesq Algorithm  

Microsoft Academic Search

We study the natural convection heat transfer in a tilted square cavity with different tilt angles. The cavity is subject to a high gradient temperature resulting in high Rayleigh number flows. The fluid is air and is treated as an ideal gas. The flow is laminar. The fluid properties change with temperature variation using Sutherland's law. Because of imposing large

S. F. Hosseinizadeh; M. Darbandi; M. Heidarnataj

2010-01-01

334

Relationship of bed and bank resistance to total flow resistance in a high gradient stream, Fraser Experimental Forest, Colorado, USA  

Microsoft Academic Search

The relative influence of bank resistance versus bed resistance on the total flow resistance in a high gradient system has been a source of debate, but because of the difficulty of making measurements in these systems has rarely been explored. Nine step-pool and five cascade reaches were surveyed over five stages in Fraser Experimental Forest, Colorado, using a combination of

G. C. David; E. E. Wohl; S. E. Yochum

2010-01-01

335

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

NASA Astrophysics Data System (ADS)

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

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

2011-07-01

336

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

SciTech Connect

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

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

2005-12-01

337

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

PubMed

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

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

2012-02-06

338

Glassy ferromagnetism and magnetic phase separation in La1-xSrxCoO3  

Microsoft Academic Search

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

J. Wu; C. Leighton

2003-01-01

339

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

Microsoft Academic Search

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

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

2010-01-01

340

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

NASA Astrophysics Data System (ADS)

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

Prutkin, Ilya; Bleibinhaus, Florian; Jahr, Thomas

2013-04-01

341

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

Microsoft Academic Search

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

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

2010-01-01

342

Characterization of reach velocity and detailed geometry in well-vegetated, high-gradient streams  

NASA Astrophysics Data System (ADS)

We developed field procedures for relating complex spatial patterns in channel geometry and roughness elements to flow resistance of mountain streams. High gradient, forested stream reaches in the U.S. Forest Service's Fraser Experimental Forest, of Colorado, were characterized using Rhodamine WT dye tracing for average reach velocity and LiDAR scans for reach geometry. The dye tracing technique consists of an injection of 20 percent rhodamine WT dye solution, with concentrations measured every second at the upstream and downstream limits of the reach using two Turner Designs Cyclops 7 fluorometers linked with two Campbell Scientific CR10X dataloggers and a calibration relating voltage output with concentration. Reach-averaged velocity was computed with the thalweg distance and both the time between peaks and the time between center of mass of the tracer pulse. Geometric data for points above the low flow water level were collected using a tripod-mounted Leica HDS LiDAR scanner. Reaches were scanned from multiple directions to minimize shadow. Targets were set up over at least two control points, for each scan, to register the scan into a consistent coordinate system. The LiDAR scans were combined with detailed total station surveys of features below the water surface. With the joining of multiple data sources, proper survey control was essential for data compatibility. The LiDAR and total station bed surveys were merged into a common pointcloud and the resulting data were cleaned to improve clarity. From this merged and cleaned pointcloud, a wide variety of geometric characteristics can be measured in the office, as the need arises. Specific characteristics will support such analyses as the determination of reach section hydraulic variables, and the use of spatial-statistical, tracer skewness and bank/bed form as indicators of roughness.

Yochum, S. E.; Bledsoe, B. P.; David, G. C.; Wohl, E. E.

2008-12-01

343

Macroinvertebrate community responses to gravel augmentation in a high-gradient, Southeastern regulated river  

SciTech Connect

Sediment transport, one of the key processes of river systems, is altered or stopped by dams, leaving lower river reaches barren of sand and gravel, both of which are essential habitat for fish and macroinvertebrates. One way to compensate for losses in sediment is to supplement gravel to river reaches below impoundments. Because gravel addition has become a widespread practice, it is essential to evaluate the biotic response to restoration projects in order to improve the efficacy of future applications. The purpose of our study was to evaluate the response of the macroinvertebrate community to gravel addition in a high-gradient, regulated river in western North Carolina. We collected benthic macroinvertebrate samples from gravel-enhanced areas and unenhanced areas for 1 season before gravel addition, and for 4 seasons afterwards. Repeated measures multivariate analysis of variance indicated that the responses of macroinvertebrates to gravel addition were generally specific to individual taxa or particular functional feeding groups and did not lead to consistent patterns in overall family richness, diversity, density, or evenness. Non-metric multi-dimensional scaling showed that shifts in macroinvertebrate community composition were temporary and dependent upon site conditions and season. Correlations between macroinvertebrate response variables and substrate microhabitat variables existed with or without the inclusion of data from enhanced areas, which suggests that substrate-biotic relationships were present before gravel addition. A review of the current literature suggests that the responses of benthic macroinvertebrates to substrate restoration are inconsistent and dependent upon site conditions and the degree habitat improvement of pre-restoration site conditions.

McManamay, Ryan A [ORNL; Orth, Dr. Donald J [Virginia Polytechnic Institute and State University; Dolloff, Dr. Charles A [United States Department of Agriculture (USDA), United States Forest Service (USFS) and Virginia Pol

2013-01-01

344

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

Microsoft Academic Search

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

S. V. Kotunov; A. V. Vlasko

2007-01-01

345

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

Microsoft Academic Search

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

Jun Jing; Z. G. Lü; H. R. Ma

2006-01-01

346

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

NASA Astrophysics Data System (ADS)

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

Tarr, Lucas; Longcope, Dana; Millhouse, Margaret

2013-06-01

347

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

Microsoft Academic Search

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

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

348

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

Microsoft Academic Search

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

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

2011-01-01

349

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

Microsoft Academic Search

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

Jinxin Li; Jinjun Zhang; Haijun Yang; Yongcheng Ning

2006-01-01

350

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

NASA Astrophysics Data System (ADS)

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

Tanaka, M.; Amemiya, K.

2000-02-01

351

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

Microsoft Academic Search

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

Wei-Wei Wang; Jia-Liang Yao

2010-01-01

352

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

Microsoft Academic Search

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

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

1998-01-01

353

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

Microsoft Academic Search

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

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

2006-01-01

354

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

PubMed

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

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

2013-08-12

355

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

PubMed

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

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

2012-02-22

356

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

Microsoft Academic Search

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

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

2005-01-01

357

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

Microsoft Academic Search

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

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

1992-01-01

358

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

Microsoft Academic Search

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

E. J. Noonan; D. W. Longcope

1999-01-01

359

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

Microsoft Academic Search

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

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

2011-01-01

360

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

Microsoft Academic Search

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

Yashita

1984-01-01

361

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

Microsoft Academic Search

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

Yashita

1983-01-01

362

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

NASA Astrophysics Data System (ADS)

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

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

2006-09-01

363

Phase-separated alloys for bulk exchange-biased permanent magnets  

SciTech Connect

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

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

2006-04-15

364

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

PubMed

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

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

2010-06-15

365

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

NASA Astrophysics Data System (ADS)

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

Thiagarajan, Arunachalam

366

Suppression of magnetic phase separation in epitaxial SrCoOX films  

NASA Astrophysics Data System (ADS)

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

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

2013-04-01

367

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

SciTech Connect

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

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

2011-12-01

368

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

NASA Astrophysics Data System (ADS)

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

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

1996-07-01

369

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

SciTech Connect

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

Yashita, S.

1983-01-01

370

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

SciTech Connect

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

Yashita, S.

1984-02-01

371

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

SciTech Connect

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

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

2008-09-07

372

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

PubMed

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

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

2012-01-03

373

KA-BAND TEST FACILITY FOR HIGH GRADIENT ACCELERATOR R&D  

Microsoft Academic Search

Achievement of high acceleration gradients in room- temperature structures requires basic studies of electrical and magnetic RF field limits at surfaces of conductors and dielectrics. Facilities for such studies at 11.4 GHz have been in use at KEK and SLAC; facilities for studies at 17.1 GHz are being developed at MIT and UMd; and studies at 30 GHz are being

M. A. LaPointe; A. A. Bogdashov; A. B. Chirkov; G. G. Denisov; J. L. Hirshfield; E. V. Kozyrev; S. V. Kuzikov; A. G. Litvak; D. A. Lukovnikov; V. I. Malygin; O. A. Nezhevenko; Yu. V. Rodin; G. V. Serdobintsev; S. V. Shchelkunov; M. Y. Shmelyov; M. I. Petelin; A. L. Vikharev; V. P. Yakovlev; BINP SB RAS; RAS Nizhny Novgorod

2006-01-01

374

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

NASA Astrophysics Data System (ADS)

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

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

2002-02-01

375

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

PubMed

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

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

2011-11-03

376

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

NASA Astrophysics Data System (ADS)

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

Sircombe, Keith N.; Stern, Richard A.

2002-07-01

377

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

SciTech Connect

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

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

2008-01-01

378

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

NASA Astrophysics Data System (ADS)

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

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

2012-05-01

379

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

PubMed

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

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

2013-04-15

380

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

SciTech Connect

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

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

2011-01-01

381

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

Microsoft Academic Search

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

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

2002-01-01

382

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 ...

383

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

Microsoft Academic Search

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

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

2002-01-01

384

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

PubMed

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

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

2013-09-19

385

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

PubMed

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

Wang, Ruoyu; Wang, Yang; Xue, Cheng; Wen, Tingting; Wu, Jinhua; Hong, Junli; Zhou, Xuemin

2013-02-18

386

Multifunctional inorganic-organic hybrid nanospheres for rapid and selective luminescence detection of TNT in mixed nitroaromatics via magnetic separation.  

PubMed

Rapid, sensitive and selective detection of 2,4,6-trinitrotoluene (TNT) in aqueous solution differentiating from other nitroaromatics and independent of complicated instruments is in high demand for public safety and environmental monitoring. Despite of many methods for TNT detection, it is hard to differentiate TNT from 2,4,6-trinitrophenol (TNP) due to their highly similar structures and properties. In this work, via a simple and versatile method, LaF3?Ce(3+)-Tb(3+)and Fe3O4 nanoparticle-codoped multifunctional nanospheres were prepared through self-assembly of the building blocks. The luminescence of these nanocomposites was dramatically quenched via adding nitroaromatics into the aqueous solution. After the magnetic separation, however, the interference of other nitroaromatics including 2,4,6-trinitrophenol (TNP), 2,4-dinitrotoluene (DNT), and nitrobenzene (NB) was effectively overcome due to the removal of these coexisting nitroaromatics from the surface of nanocomposites. Due to the formation of TNT(-)-RCONH3(+), the TNT was attached to the surface of the nanocomposites and was quantitatively detected by the postexposure luminescence quenching. Meanwhile, the luminescence intensity is negatively proportional to the concentration of TNT in the range of 0.01-5.0?g/mL with the 3? limit of detection (LOD) of 10.2ng/mL. Therefore, the as-developed method provides a novel strategy for rapid and selective detection of TNT in the mixture solution of nitroaromatics by postexposure luminescence quenching. PMID:24148441

Ma, Yingxin; Huang, Sheng; Wang, Leyu

2013-07-20

387

Improving the binding capacity of Ni2+ decorated porous magnetic silica spheres for histidine-rich protein separation.  

PubMed

Biomagnetic immobilization of histidine-rich proteins based on the single-step affinity adsorption of transition metal ions continues to be a suitable practice as a cost effective and a up scaled alternative to the to multiple-step chromatographic separations. In our previous work, we synthesised Porous Magnetic silica (PMS) spheres by one-step hydrothermal-assisted modified-stöber method. The obtained spheres were decorated with Ni(2+) and Co(2+), and evaluated for the capture of a H6-Tagged green fluorescence protein (GFP-H6) protein. The binding capacity of the obtained spheres was found to be slightly higher in the case Ni(2+) decorated PMS spheres (PMSNi). However, comparing with commercial products, the binding capacity was found to be lower than the expected. In this way, the present work is an attempt to improve the binding capacity of PMSNi to histidine-rich proteins. We find that increasing the amount of Ni(2+) onto the surface of the PMS spheres leads to an increment of the binding capacity to GFP-H6 by a factor of two. On the other hand, we explore how the size of histidine-rich protein can affect the binding capacity comparing the results of the GFP-6H to those of the His-tagged ?-galactosidase (?-GLA). Finally, we demonstrate that the optimization of the magnetophoresis parameters during washing and eluting steps can lead to an additional improvement of the binding capacity. PMID:23010043

Benelmekki, M; Caparros, C; Xuriguera, E; Lanceros-Mendez, S; Rodriguez-Carmona, E; Mendoza, R; Corchero, J L; Martinez, Ll M

2012-07-21

388

Preparation of anti-CD4 monoclonal antibody-conjugated magnetic poly(glycidyl methacrylate) particles and their application on CD4+ lymphocyte separation.  

PubMed

Novel immunomagnetic particles have been prepared for separation of CD4(+) lymphocytes. The magnetic nanoparticles with a diameter of approximately 5-6 nm were first synthesized by co-precipitation from ferrous and ferric iron solutions and subsequently encapsulated with poly(glycidyl methacrylate) (PGMA) by precipitation polymerization. Monoclonal antibody specific to CD4 molecules expressed on CD4(+) lymphocytes was conjugated to the surface of magnetic PGMA particles through covalent bonding between epoxide functional groups on the particle surface and primary amine groups of the antibodies. The generated immunomagnetic particles have successfully separated CD4(+) lymphocytes from whole blood with over 95% purity. The results indicated that these particles can be employed for cell separation and provide a strong potential to be applied in various biomedical applications including diagnosis, and monitoring of human diseases. PMID:21315903

Pimpha, Nuttaporn; Chaleawlert-umpon, Saowaluk; Chruewkamlow, Nuttapol; Kasinrerk, Watchara

2010-12-25

389

A novel magnetically separable gamma-Fe2O3/crosslinked chitosan adsorbent: preparation, characterization and adsorption application for removal of hazardous azo dye.  

PubMed

A novel magnetically separable adsorbent, namely magnetic gamma-Fe(2)O(3)/crosslinked chitosan composites (Mgamma-Fe(2)O(3)/CSCs), was prepared by microemulsion process and characterized by XRD, FT-IR, TGA, DSC, SEM and VSM. Adsorption of methyl orange (MO), used as a model pollutant, from aqueous solution on Mgamma-Fe(2)O(3)/CSCs was investigated. Characterization results indicated that magnetic gamma-Fe(2)O(3) nanoparticles have been introduced in Mgamma-Fe(2)O(3)/CSCs and kept intrinsic magnetic properties. The saturated magnetization (sigma(s)) of Mgamma-Fe(2)O(3)/CSCs can be expediently adjusted by changing additive dosage of gamma-Fe(2)O(3). Adsorption results showed that both nanocomposite adsorbents with weight ratio of gamma-Fe(2)O(3) to chitosan of 1:10 and 2:5 exhibited higher adsorption capacities and attained adsorption equilibria in shorter time compared with crosslinked chitosan. After adsorption, Mgamma-Fe(2)O(3)/CSCs were effectively separated from reaction solution in 10s by applying an adscititious magnetic field. Adsorption kinetics of MO on 1:10 Mgamma-Fe(2)O(3)/CSCs followed the pseudo-second-order kinetic model. Effects of both initial pH and adsorbent dosage on the adsorption of MO were remarkable in experimental conditions. PMID:20334972

Zhu, Hua-Yue; Jiang, Ru; Xiao, Ling; Li, Wei

2010-03-03

390

In-plane magnetic pattern separation in NiFe/NiO and Co/NiO exchange biased bilayers investigated by magnetic force microscopy  

NASA Astrophysics Data System (ADS)

Ion bombardment induced magnetic patterning (IBMP) was used to write in-plane magnetized micro and submicron patterns in exchange biased magnetic bilayers, where the magnetization directions of the adjacent patterns are antiparallel to each other in remanence. These magnetic patterns were investigated by non-contact magnetic force microscopy (MFM). It is shown that the recorded MFM images of the IBMP patterns in two exemplarily chosen standard layer systems (NiFe(4.8nm)/NiO(68nm) and Co(4.8nm)/NiO(68nm)) can be well described by a model within the point-dipole approximation for the tip magnetization. For 5 and 0.9?m wide bar patterns the domain wall widths between adjacent magnetically patterned areas were determined to a~1?m. The minimum magnetically stable pattern width was estimated to be 0.7?m in the standard system Co(4.8nm)/NiO(68nm).

Ehresmann, A.; Krug, I.; Kronenberger, A.; Ehlers, A.; Engel, D.

2004-09-01

391

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

NASA Astrophysics Data System (ADS)

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

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

2013-09-01

392

Interaction region magnets for VLHC  

Microsoft Academic Search

The interaction region (IR) magnets for the proposed Very Large Hadron Collider (VLHC) require high gradient quadrupoles and high field dipoles for high luminosity performance. Moreover, the IR magnets for high energy colliders and storage rings must operate in an environment where the amount of energy deposited on superconducting coils is rather large. In the case of doublet IR optics

Ramesh Gupta; Michael Harrison

2002-01-01

393

Exploring the effect of Al2O3 ALD coating on a high gradient ILC single-cell cavity  

SciTech Connect

Encouraged by work at Argonne National Lab, we investigated atomic layer deposition technique (ALD) for high gradient superconducting RF cavities at JLab with an ALD coating system of Old Dominion University located on the JLab site. The goal of this study was to look into the possibility of coating a dielectric layer on top of RF niobium surface at a lower temperature of 120 C as compared to ANL coatings at 200 C to preserve niobium pentoxide on niobium surface. The initial coatings showed complete, but non-uniform coatings of the surface with several areas exhibiting discoloration, which was probably due to the temperature variation across the cavity surface. The initial coating showed a high RF losses, which were improved after discolored areas on the beam tubes were removed with HF rinse of the beam tubes only. The best result was 2 109 low field Q0 and Eacc = 18 MV/m limited by available power.

Grigory Eremeev, Anne-Marie Valente, Andy Wu, Diefeng Gu

2012-07-01

394

Orientation dependence of the interfacial magnetic phase separation in epitaxial La1-xSrxCoO3 films on SrTiO3 and LaAlO3 substrates  

Microsoft Academic Search

We have observed interfacial magneto-electronic phase separation in epitaxial films of La1-xSrxCoO3 (x > 0.18) on SrTiO3 (001) substrates, where no such phase separation occurs in the bulk. This magnetic phase separation was detected indirectly via reduced magnetization, insulating transport, and the presence of intercluster type GMR, and subsequently verified directly by small-angle neutron scattering. Z contrast STEM\\/EELS results reveal

M. Sharma; M. A. Torija; J. Schmidt; C. He; C. Leighton; J. Gazquez; M. Varela; M. Laver; S. El-Khatib; B. B. Maranville; J. A. Borchers; M. Zhernenkov; M. R. Fitzsimmons

2010-01-01

395

Anomalous phase separation in La0.225Pr0.4Ca0.375MnO3: consequence of temperature and magnetic-field cycles  

NASA Astrophysics Data System (ADS)

The evolutions of electronic phase separation in manganites La0.225Pr0.4Ca0.375MnO3 are studied by the specific temperature and magnetic-field cycling experiments. It is found that the electronic phase separation state at low temperature can be tuned substantially by temperature and/or magnetic-field cycles. Surprisingly, the initial more ferromagnetic metallic (FMM) nuclei can impede the growth of these nuclei during the cooling process. It implies that there must coexist more than two phases which take part in the complex first-order phase transitions, and the charge-disordered insulating phase is possible, one of the parent phases transiting into the FMM phase at low temperature. In addition, the accommodation strain is suggested to control the nucleation and growth of FMM domains.

Yan, Z. B.; Liu, J.-M.

2011-07-01

396

Application of a Peptide-Mediated Magnetic Separation-Phage Assay for Detection of Viable Mycobacterium avium subsp. paratuberculosis to Bovine Bulk Tank Milk and Feces Samples?†  

PubMed Central

Naturally contaminated bovine bulk tank milk (n = 44) and feces (n = 39) were tested for the presence of viable Mycobacterium avium subsp. paratuberculosis by a novel peptide-mediated magnetic separation-phage (PMS-phage) assay. Counts of viable M. avium subsp. paratuberculosis cells ranging from 1 to 110 PFU/50 ml of milk and 6 to 41,111 PFU/g of feces were indicated by the PMS-phage assay.

Foddai, Antonio; Strain, Samuel; Whitlock, Robert H.; Elliott, Christopher T.; Grant, Irene R.

2011-01-01

397

Magnetism.  

National Technical Information Service (NTIS)

This program describes magnets and magnetic materials by pointing out the characteristics of the magnetic field, the molecular arrangement of magnetized and unmagnetized metals, the laws of attraction and repulsion, and the factors that affect the amount ...

1972-01-01

398

An integrated passive micromixer-magnetic separation-capillary electrophoresis microdevice for rapid and multiplex pathogen detection at the single-cell level.  

PubMed

Here we report an integrated microdevice consisting of an efficient passive mixer, a magnetic separation chamber, and a capillary electrophoretic microchannel in which DNA barcode assay, target pathogen separation, and barcode DNA capillary electrophoretic analysis were performed sequentially within 30 min for multiplex pathogen detection at the single-cell level. The intestine-shaped serpentine 3D micromixer provides a high mixing rate to generate magnetic particle-pathogenic bacteria-DNA barcode labelled AuNP complexes quantitatively. After magnetic separation and purification of those complexes, the barcode DNA strands were released and analyzed by the microfluidic capillary electrophoresis within 5 min. The size of the barcode DNA strand was controlled depending on the target bacteria (Staphylococcus aureus, Escherichia coli O157:H7, and Salmonella typhimurium), and the different elution time of the barcode DNA peak in the electropherogram allows us to recognize the target pathogen with ease in the monoplex as well as in the multiplex analysis. In addition, the quantity of the DNA barcode strand (?10(4)) per AuNP is enough to be observed in the laser-induced confocal fluorescence detector, thereby making single-cell analysis possible. This novel integrated microdevice enables us to perform rapid, sensitive, and multiplex pathogen detection with sample-in-answer-out capability to be applied for biosafety testing, environmental screening, and clinical trials. PMID:21870015

Jung, Jae Hwan; Kim, Gha-Young; Seo, Tae Seok

2011-08-25

399

Magnetic properties of phase separated Fe3O4-TiO2-SiO2 glasses prepared from a two-liquids immiscible melt  

NASA Astrophysics Data System (ADS)

The glassy composite materials were prepared by quenching the phase separated melts in two-liquids immiscibility region of Fe3O4-TiO2-SiO2 ternary system. The fine phase-separation textures which consisted of Fe-Ti rich phase and Si rich one were formed in the samples, and the precipitation of Fe3O4-TiO2 solid solution was observed in the samples of the specific compositions. The samples containing Fe3O4-TiO2 solid solution showed ferrimagnetic properties on their magnetization curves. In low Fe3O4-TiO2 content, coercivity increased with increase of Fe3O4-TiO2 content since the precipitated particles in the samples grew and had single magnetic domain. In high Fe3O4-TiO2 content, the coercivity decreased with increase of Fe3O4-TiO2 content because the magnetostatical interparticle interaction among the precipitated particles appeared. These results indicate that the magnetic properties of the composite materials owing to the crystalline phase and its size can be controlled by utilizing the phase separation in this system.

Kono, K.; Kishi, T.; Ohgaki, T.; Yasumori, A.

2008-03-01

400

Simple synthesis of functionalized superparamagnetic magnetite/silica core/shell nanoparticles and their application as magnetically separable high-performance biocatalysts  

SciTech Connect

We report on the facile large-scale synthesis of magnetite@silica core-shell nanoparticles by a simple addition of tetraethyl orthosilicate (TEOS) into reverse micelles during the formation of uniformly-sized magnetite nanoparticles. The size of magnetic core was determined by the ratio of solvent and surfactant in reverse micelle solution while the thickness of silica shell could be easily controlled by adjusting the amount of added TEOS. Amino group functional groups were grafted to the magnetic nanoparticles, and crosslinked enzyme clusters (CEC) were fabricated on the surface of magnetite@silica nanoparticles. The resulting hybrid materials of magnetite and CEC were magnetically separable, highly active, and stable enough to show no decrease of enzyme activity under rigorous shaking for more than 15 days.

Lee, Jinwoo; Lee, Youjin; Youn, Jongkyu; Na, Hyon Bin; Yu, Taekyung; Kim, Hwan O.; Lee, Sang-mok; Koo, Yoon-mo; Kwak, Ja Hun; Park, Hyun-Gyu; Chang, Ho Nam; Hwang, Misun; Park, Je-Geun; Kim, Jungbae; Hyeon, Taeghwan

2008-01-01

401

Structure, Composition and Magnetic Properties of Ferrofluid Nanoparticles after Separation / Feromagn?tisko Š?idrumu Nanoda?i?u Strukt?ras, Sast?va un Magn?tisko ?paš?bu Izmai?as P?c Separ?cijas  

NASA Astrophysics Data System (ADS)

The structure, composition and magnetic properties of iron oxide nanoparticles are studied as dependent on the synthesis technology and method of separation in ferrofluids. The goal of the present study is to improve the magnetic properties of wet-synthesized nanoparticles and achieve a narrow nanoparticle size distribution. The results of measurements show that by varying the conditions of the chemical coprecipitation method, different compositions and structures of the nanoparticles could be obtained. The separation of ferrite nanoparticles of a polydisperse colloid by centrifugation as well as by HGMS provides the possibility to obtain a nanoparticle set with narrow size distribution Darb? izp?t?tas dzelzs oks?da nanoda?i?u strukt?ras, sast?va un magn?tisko ?paš?bu izmai?as atkar?b? no sint?zes tehnolo?ijas, k? ar? no daž?d?m feromagn?tisko š?idrumu separ?cijas metod?m. Magn?tisko nanoda?i?u strukt?ra, sast?vs un izm?rs tika p?t?ts ar rentgenstaru difraktometru un transmisijas elektronu mikroskopu. Da?i?u magn?tisk?s ?paš?bas tika m?r?tas ar vibr?cijas magnetometru. P?t?jum? par?d?ts, ka, mainot magn?tisko nanoda?i?u sint?zes apst?k?us, k? ar?, separ?jot feromagn?tisko š?idrumu ar daž?d?m metod?m, var izgatavot paraugus ar nepieciešamaj?m specifiskaj?m ?paš?b?m

Kronkalns, G.; Kodols, M.; Maiorov, M. M.

2013-08-01

402

Synthesis of Fe3O4@poly(methylmethacrylate-co-divinylbenzene) magnetic porous microspheres and their application in the separation of phenol from aqueous solutions.  

PubMed

A simple strategy to fabricate magnetic porous microspheres of Fe(3)O(4)@poly(methylmethacrylate-co-divinylbenzene) was demonstrated. The magnetic microspheres, consisting of polymer-coated iron oxide nanoparticles, were synthesized by the modified suspension polymerization of methacrylate and divinylbenzene in the presence of a magnetic fluid. The morphology and the properties of the magnetic porous microspheres were examined by scanning electron microscopy, transmission electron microscopy, superconducting quantum interference device, Fourier transform infrared spectroscopy, thermogravimetry, and X-ray powder diffraction. The pore size distribution and the specific surface area of the microspheres were measured by nitrogen sorption and mercury porosimetry technique. As predicted from the previous knowledge, the magnetic porous microspheres possessed a high specific surface area using n-hexane as a porogen. It was further found that the amounts of divinylbenzene and methacrylate, the ratio of porogens, and the dosage of ferrofluids affect the specific surface area of the microspheres. Furthermore, the microspheres were applied to remove phenol from aqueous solutions. The results showed that the microspheres had a high adsorption capacity for phenol and a high separation efficiency due to their porous structure, polar groups, and superparamagnetic characteristic. PMID:21601864

Tai, Yulei; Wang, Li; Gao, Jingmin; Amer, Wael A; Ding, Wenbing; Yu, Haojie

2011-05-04

403

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

NASA Astrophysics Data System (ADS)

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

Leighton, Chris

2012-02-01

404

Relationship of bed and bank resistance to total flow resistance in a high gradient stream, Fraser Experimental Forest, Colorado, USA  

NASA Astrophysics Data System (ADS)

The relative influence of bank resistance versus bed resistance on the total flow resistance in a high gradient system has been a source of debate, but because of the difficulty of making measurements in these systems has rarely been explored. Nine step-pool and five cascade reaches were surveyed over five stages in Fraser Experimental Forest, Colorado, using a combination of a laser theodolite and LiDAR (Light Detection and Ranging). The LiDAR was used to capture banks and channel geometry at low flows, whereas the water surface and bed data were collected with the laser theodolite at both low and high flows. Reach-averaged mean velocity was measured using fluorometers and Rhodamine WT dye tracers. The roughness created by the bed and banks were calculated using the standard deviation of the residuals of a longitudinal profile regression (?bank and ?bed). In addition, hyperspectral and spectral analysis are used to characterize the bed, banks, and water surface during both base and bankfull flows. The three methods of characterizing the roughness created by the bed and banks are used to ascertain relative influence of the banks versus the bed on total flow resistance. These data are used to evaluate three hypotheses: i) step-pool bed morphology has a distinctively different spectral signature than cascade bed morphology; ii) the bed and bank resistance can be evaluated using either standard deviation of the residuals or by hyperspectral analysis and related to total flow resistance; iii) potential controls on bank resistance include both gradient and grain size, which differ based on channel type (step-pool versus cascade). Preliminary results indicate that both step-pool and cascade channel morphologies can be evaluated using spectral analysis despite the short reach lengths (? 30 m). Evaluation of ?bed indicated that there is no significant difference between means for step-pool (0.145) versus cascade (0.163) reaches, but the boxplots show a greater variability in the values of ?bed for step-pool reaches. Furthermore, there was no significant difference in the value of ?bank for step-pool (0.656) versus cascade (0.692) reaches. Both gradient and grain size are significant controls of ?bank. The larger grain sizes led to higher values of ?bank, most likely from larger boulders forcing flows towards the banks creating an irregular pattern of erosion. At bank filling flows the bank resistance was found to be significantly related to total flow resistance, with flow resistance increasing as ?bank increased.

David, G. C.; Wohl, E. E.; Yochum, S. E.

2010-12-01

405

Possible magnetic phase separation in Ru-doped La 0.67Ca 0.33MnO 3  

Microsoft Academic Search

X-ray diffraction, resistivity, AC susceptibility and magnetization studies on La0.67Ca0.33Mn1?xRuxO3 (0?x<0.085) were carried out. A significant increase in the lattice parameters indicated the presence of mixed valence state of Ru: Ru3+ and Ru4+. The resistivity of the doped compounds exhibited two features: a broad hump and a relatively sharp peak. While a para- to ferromagnetic transition could be observed for

L. Seetha Lakshmi; V. Sridharan; D. V. Natarajan; Sharat Chandra; V. Sankara Sastry; T. S. Radhakrishnan; Ponn Pandian; R. Justine Joseyphus; A. Narayanasamy

2003-01-01

406

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

Microsoft Academic Search

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

Dževad Belki?; Karen Belki?

2009-01-01

407

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

SciTech Connect

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

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

2009-10-15

408

Field alignment of quadrupole magnets for the LHC interaction regions  

Microsoft Academic Search

High-gradient superconducting quadrupole magnets are being developed by the US LHC Accelerator Project for the Interaction Regions of the Large Hadron Collider. Determination of the magnetic axis for alignment of these magnets will be performed using a single stretched wire system. These measurements will be done both at room and cryogenic temperatures with very long wire lengths, up to 20

J. DiMarco; H. Glass; M. J. Lamm; P. Schlabach; C. Sylvester; J. C. Tompkins; I. Krzywinski

2000-01-01

409

Phase separation in Fe-Si and Co-Si sputtered ferromagnetic alloys and the origin of their magnetic anisotropy  

SciTech Connect

Fe-Si and Co-Si thin films were studied with different Si concentrations by x-ray absorption spectroscopy (XAFS), and the analysis was confronted to their magnetic properties of coercivity and anisotropy. The analysis of the XAFS spectra showed a higher disorder in the amorphous Fe-Si films than in the Co-Si films and a larger degree of clustering of Co atoms, consistent with the higher heat of alloying of Fe-Si with respect to Co-Si alloys. Both kinds of amorphous films contained a strongly disordered silicide phase that was hardly detected by extended XAFS spectroscopy (EXAFS). EXAFS spectra were dominated by the nonmagnetic (Fe,Co)Si{sub 2} environments. The orientation of the magnetic easy axis of the films was correlated with the expected anisotropic spatial distribution of Si concentration, which was defined by the oblique angle of incidence of Si atoms during film deposition. This indicates that such a detected nonmagnetic Si rich environments were anisotropically distributed and possibly segregated, influencing in a significant way the magnetic anisotropy of these films.

Diaz, J.; Morales, R.; Valvidares, S.M.; Alameda, J.M. [Departamento de Fisica, Universidad de Oviedo, Avenida de Calvo Sotelo s/n, Oviedo-33007 (Spain)

2005-10-01

410

Recovery of metals from Cuban nickel tailings by leaching with organic acids followed by precipitation and magnetic separation.  

PubMed

The percolation leaching of the Cuban nickel tailings containing 0.34% Ni, 0.08% Co and 44.2% Fe was investigated by using tartaric and oxalic acids at different concentrations. About 70% Ni, 80% Co and 30% Fe were extracted after 5 days of leaching with the mixture of 0.15 mol/L tartaric acid and 0.05 mol/L oxalic acid at ambient temperature and normal pressure. Nickel and cobalt extraction of 80% as well as iron extraction of 50% were achieved from the pregnant solution by means of precipitation at 80 degrees C for 2h. The precipitation at ambient temperature led to a similar result after 16 days. Cobalt, nickel and iron oxalates were found in the precipitate by using the X-ray diffraction method. The regeneration of acids during the precipitation step made possible the reuse of the raffinate at the leaching step. Heating of the precipitate at 200 degrees C increased the metal concentration to 1.22% Ni and 0.33% Co, which can be fed in the existing nickel plant in Moa, Cuba. The magnetic processing of the leaching residues led to a non-magnetic product containing less than 20% Fe and a magnetic product containing more than 50% Fe. PMID:17084523

Hernández, C M F; Banza, A N; Gock, E

2006-09-23

411

Magnetism  

NSDL National Science Digital Library

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

Team, University C.

2007-12-12

412

Efficient separation and sensitive detection of Listeria monocytogenes using an impedance immunosensor based on magnetic nanoparticles, a microfluidic chip, and an interdigitated microelectrode.  

PubMed

Listeria monocytogenes continues to be a major foodborne pathogen that causes food poisoning, and sometimes death, among immunosuppressed people and abortion among pregnant women. In this study, magnetic nanoparticles with a diameter of 30 nm were functionalized with anti-L. monocytogenes antibodies via biotin-streptavidin bonds to become immunomagnetic nanoparticles (IMNPs) to capture L. monocytogenes in a sample during a 2-h immunoreaction. A magnetic separator was used to collect and hold the IMNPs-L. monocytogenes complex while the supernatants were removed. After the washing step, the nanoparticle-L. monocytogenes complex was separated from the sample and injected into a microfluidic chip. The impedance change caused by L. monocytogenes was measured by an impedance analyzer through the interdigitated microelectrode in the microfluidic chip. For L. monocytogenes in phosphate-buffered saline solution, up to 75% of the cells in the sample could be separated, and as few as three to five cells in the microfluidic chip could be detected, which is equivalent to 10(3) CFU/ml of cells in the original sample. The detection of L. monocytogenes was not interfered with by other major foodborne bacteria, including E. coli O157:H7, E. coli K-12, L. innocua, Salmonella Typhimurium, and Staphylococcus aureus. A linear correlation (R(2) = 0.86) was found between the impedance change and the number of L. monocytogenes in a range of 10(3) to 10(7) CFU/ml. Equivalent circuit analysis indicated that the impedance change was mainly due to the decrease in medium resistance when the IMNPs-L. monocytogenes complexes existed in mannitol solution. Finally, the immunosensor was evaluated with food sample tests; the results showed that, without preenrichment and labeling, 10(4) and 10(5) CFU/ml L. monocytogenes in lettuce, milk, and ground beef samples could be detected in 3 h. PMID:23127703

Kanayeva, Damira A; Wang, Ronghui; Rhoads, Douglas; Erf, Gisela F; Slavik, Michael F; Tung, Steve; Li, Yanbin

2012-11-01

413

Synthesis of chitosan networks: Swelling, drug release, and magnetically assisted BSA separation using Fe3O4 nanoparticles.  

PubMed

Chitosan (CS) nanohydrogel networks were prepared by reaction with glyceroldiglycidylether (GDE) and poly(dimethylsiloxane) (PDMS), as crosslinking agents in an emulsion system. The nanogel content increased with increasing the amount of crosslinkers and reached to a maximum of 90% with GDE. The nanogels structure was characterized by FT-IR, AFM, DSC, and TGA. The average size for CS-GDE and CS-PDMS particles were 59nm and 180nm, respectively. The swelling behavior of nanohydrogels was observed to be dependent on pH, temperature, degree of crosslinking, and on the chemical structure of crosslinker. The equilibrium water content of CS-GDE nanohydrogels reached to a maximum of 600% at neutral pH, and decreased at high and low pH and low temperature. These nanohydrogels were tested for sodium diclofenac (SDF) loading and releasing efficiency. The covalent conjugation of bovine serum albumin (BSA) and magnetic Fe(3)O(4) nanoparticles on the hydrogels were found to hold a potential application in magnetically assisted bioseparation. PMID:22939340

Ghaemy, Mousa; Naseri, Motahare

2012-07-02

414

Analysis of the Cause of High External Q Modes in the JLab High Gradient Prototype Cryomodule Renascence  

SciTech Connect

The Renascence cryomodule [1] installed in CEBAF in 2007 consists of 8 cavities as shown in Figure 1. The first three cavities (No.1-No.3) in the upstream end are of the Low Loss (LL) shape design, and the remaining 5 cavities (No.4-No.8) on the beam downstream end are the High Gradient (HG) shape design. The fundamental power couplers (FPCs) are the rectangular waveguides, and the little cylindrical structures are the HOM couplers. The locations of the FPC in the last four cavities are mirrored about the beam z axis. Cavities No.4 and No.5 form a back-to-back cavity pair. Among the HG cavities installed in the Renascence cryomodule, the only identifiable difference from their fabrication documentation is that cavity No.5 received an extra EBW pass on one equator weld, specifically cell 5. The non-uniform mechanical tuning required to compensate the fundamental mode tune and flatness for the extra shrinkage of this cell is believed to contribute the most significant differences from the other HG cavities. Beam based instability studies on this cryomodule in CEBAF have shown a significant beam breakup (BBU) threshold current reduction, well below design value. Frequency spectrum peaked by the off-sided beam power indicated the cause is due to abnormal high Q modes in the cavity No.5. Measured beam off-axis position at the cavity No.5 does not correspond to the shunt impedances calculated for an ideal cavity. Low power RF measurements have identified that the problematic modes are in the second dipole band (TM110 like). Three of the modes have external Qs two orders magnitude higher than the others, while the rest of modes in the first two dipole bands are normal in terms of the design values. The cause of this abnormality and the future impact on the BBU was not able to be resolved due to the limitations of information that can be obtained from the measurements. It is important to understand the cause of this abnormality so that effective QA/QC measures can be implemented to avoid such problem in the final upgrade design and manufacture. The goal of this work is to utilize advanced simulation tools to understand the high external Q (Q{sub ext}) problem observed in the Renascence cryomodule. In the past years, SLAC has built a set of state-of-the-art advanced simulation tools based on finite-element unstructured meshes and parallel computation implementations on supercomputers [2, 3]. The codes are capable of simulating large complex RF systems with unprecedented resolution and turnaround time. They have been successfully applied to many existing and future accelerator R&D projects to improve the machine performance and to optimize the designs. These tools are essential to perform accurate full system analyses such as the JLab's SRF cavities. We will use the simulation results and the data from the RF measurements to gain a better understanding of the cavity performance and tolerance issues and provide a solid foundation to do the BBU simulation and prediction for the 12GeV Upgrade project by using JLab's BBU codes. In this report, we will focus on the following two main tasks: (1) Ideal cavity simulation--to evaluate the effectiveness of the damping by the higher-order-mode (HOM) couplers, and search for possible trapped modes in a back-to-back cavity pair (e.g. cavity No.4 & No.5). (2) Abnormal cavity study--to understand the cause of the high Q{sub ext} modes in cavity No.5 using an advanced Shape Determination Tool.

Li, Z.; Akcelik, V.; Xiao, L.; Lee, L.; Ng, C.; Ko, K.; /SLAC; Wang, H.; Marhauser, F.; Sekutowicz, J.; Reece, C.; Rimmer, R.; /Jefferson Lab

2008-06-27

415

High efficiency annular magnetically insulated line oscillator-transit time oscillator with three separate frequencies in three bands  

NASA Astrophysics Data System (ADS)

To increase the efficiency of the magnetically insulated line oscillator (MILO) and expand its frequency band, a coaxial transit time oscillator (TTO) is introduced to use the load currents of an annular MILO, called the annular MILO-TTO, which comprises an inward-emitting MILO, an outward-emitting MILO, and a coaxial TTO. In simulation, when the input power is 78 GW and the diode voltage is 520 kV, three microwaves with powers of 3.2, 9.6, and 7.0 GW are generated, with a total efficiency of 25.4%, in the inward-emitting MILO, the outward-emitting MILO, and the coaxial TTO, and the frequencies are 1.7, 3.3, and 4.2 GHz, corresponding to L, S, and C bands, respectively.

Xiao, Renzhen; Sun, Jun; Chen, Changhua; Zhang, Yongpeng; Shao, Hao

2009-08-01

416

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

SciTech Connect

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.

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

417

Optics of Mass Separator I.  

National Technical Information Service (NTIS)

The ion optics of an existing mass separator are documented. The elctrostatic and magnetic stages are analyzed theoretically, both separately and in combination, by paying particular attention to the ion trajectories, the linear and angular magnifications...

S. J. Balestrini

1981-01-01

418

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

SciTech Connect

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.

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

419

Magnetism  

NSDL National Science Digital Library

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

Stern, David

420

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)

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.

Barabanenkov, Yurii N.; Barabanenkov, Mikhail Y.

2013-05-01