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Sample records for 3t functional magnetic

  1. Structural and magnetic properties of TlTF3 (T=Fe, Co and Ni) by hybrid functional theory

    NASA Astrophysics Data System (ADS)

    Zeb, Raham; Ali, Zahid; Ahmad, Iftikhar; Khan, Imad

    2015-08-01

    DFT studies are performed to investigate the structural, mechanical and magneto-electronic properties of the TlTF3 (T=Fe, Co and Ni) perovskites for the first time using GGA, GGA+U and hybrid density functional theory (HF). Our calculations show that HF give better results than GGA and GGA+U and more consistent with the experiments. The comparison of the lattice constants calculated by HF with experiments shows a maximum underestimation less than 0.2%. The chemical bonding between different ions in these compounds is explained on the bases of electronic clouds, which reveals that in TlFeF3, Fe has more ionic character with F than the rest. The mechanical properties explain the hardness of these compounds and show that TlFeF3 is more ductile. Spin-dependent electronic band profiles show that TlFeF3 and TlCoF3 are metallic, whereas TlNiF3 is pseudo direct wide bandgap semiconductor. The stable magnetic phase optimizations and the calculated magnetic susceptibility confirm that TlFeF3 and TlNiF3 are ferromagnetic whereas TlCoF3 is anti-ferromagnetic material.

  2. Travelling wave magnetic resonance imaging at 3 T

    NASA Astrophysics Data System (ADS)

    Vazquez, F.; Martin, R.; Marrufo, O.; Rodriguez, A. O.

    2013-08-01

    Waveguides have been successfully used to generate magnetic resonance images at 7 T with whole-body systems. The bore diameter limits the magnetic resonance signal transmitted because its specific cut-off frequency is greater than the majority of resonant frequencies in magnetic resonance imaging and spectroscopy. This restriction can be overcome by using a parallel-plate waveguide whose cut-off frequency is zero for the transverse electromagnetic modes and it can propagate any frequency. To study the potential benefits of travelling-wave excitation for whole-body imaging at 3 T, we compare numerical simulations of the principal mode propagation for a parallel-plate waveguide filled with a cylindrical phantom and two surface coils for all simulations at 1.5 T, 3 T, 4.7, 7 T, and 9.4 T. The principal mode shows very little variation of the field magnitude along the propagation direction at 3 T when compared to other higher resonant frequencies. Unlike the standard method for travelling-wave magnetic resonance imaging, a parallel-plate waveguide prototype was built and used together with a whole-body birdcage coil for signal transmission and a pair of circular coils for reception. Experimental B1 mapping was computed to investigate the feasibility of this approach and, the point spread function method was used to measure the imager performance. Human leg images were acquired to experimentally validate this approach. The numerical magnetic field and specific absorption rate of a simulated leg were computed and results are within the safety limits. The B1 mapping and point spread function results showed that it is possible to conduct travelling-wave imaging experiments with good imager performance. Human leg images were also obtained with the whole-body birdcage coil for comparison purposes. The simulated and in vivo travelling-wave results of the human leg correspond very well for the signal received. A similar image signal-to-noise ratio was observed for the

  3. Event-related dynamics of glutamate and BOLD effects measured using functional magnetic resonance spectroscopy (fMRS) at 3T in a repetition suppression paradigm.

    PubMed

    Apšvalka, Dace; Gadie, Andrew; Clemence, Matthew; Mullins, Paul G

    2015-09-01

    Proton MR spectroscopy ((1)H-MRS) complements other brain research methods by providing measures of neurometabolites noninvasively in a localized brain area. Improvements in MR scanner technologies, and data acquisition and analysis methods should allow functional (1)H-MRS (fMRS) to measure neurometabolite concentration changes during task-induced brain activation. The aim of the current study was to further develop event-related fMRS at 3T to investigate glutamate dynamics in response to repetition suppression. A secondary aim was to investigate the relationship between blood-oxygen-level-dependent (BOLD) responses and glutamate dynamics in the same paradigm at the same time. A novel approach of interleaved water-suppressed (metabolite) and unsuppressed (water) fMRS was used to simultaneously detect the event-related dynamics of glutamate and BOLD signal to repetition suppression in the lateral occipital cortex of thirteen (N=13) volunteers. On average, (1)H-MRS-visible glutamate increased after novel visual stimuli presentations by 12% and decreased by 11-13% on repeated compared to novel presentations. The BOLD signal, as measured by water peak amplitude changes, showed significant difference between Task and Rest trials, and, on a GLM based analysis of the time series, demonstrated a significant difference between the novel and repeated trials, however appeared to be decoupled from the glutamate response as no correlation was found between the two. These results are the first demonstration that reductions in neuronal activity typical of repetition suppression effects are reflected by reduced glutamatergic and BOLD measures, that glutamate and BOLD responses may not be coupled as previously thought, and that these changes and relationships can be measured simultaneously using event-related fMRS at 3T. PMID:26072254

  4. Malformations of cortical development: 3T magnetic resonance imaging features

    PubMed Central

    Battal, Bilal; Ince, Selami; Akgun, Veysel; Kocaoglu, Murat; Ozcan, Emrah; Tasar, Mustafa

    2015-01-01

    Malformation of cortical development (MCD) is a term representing an inhomogeneous group of central nervous system abnormalities, referring particularly to embriyological aspect as a consequence of any of the three developmental stages, i.e., cell proliferation, cell migration and cortical organization. These include cotical dysgenesis, microcephaly, polymicrogyria, schizencephaly, lissencephaly, hemimegalencephaly, heterotopia and focal cortical dysplasia. Since magnetic resonance imaging is the modality of choice that best identifies the structural anomalies of the brain cortex, we aimed to provide a mini review of MCD by using 3T magnetic resonance scanner images. PMID:26516429

  5. 3 T magnetic resonance imaging of the musculoskeletal system.

    PubMed

    Guglielmi, G; Biccari, N; Mangano, F; Toffanin, R

    2010-06-01

    The increasing distribution of high-field (3 T) magnetic resonance (MR) systems for clinical use has been accompanied by the need to fully understand the advantages and disadvantages that the increase in signal quality confers. Continuous development of the coils is required to fully express the potential of these systems, especially given the synergy between parallel imaging and the recent multichannel phased-array coils, which are able to improve image quality, spatial resolution and diagnostic accuracy in musculoskeletal imaging. The increase in signal offered by the high field makes possible improved visualisation of bone, cartilage, tendons and ligaments. This advantage, together with increased spatial resolution, is particularly useful when studying joints or some of their components, the evaluation of which has produced suboptimal results in non arthrographic examinations such as the glenoid labrum of the shoulder and the articular cartilage of the knee. Thanks to the greater signal-to-noise ratio and improved spatial resolution, MR imaging at 3 T is able to notably increase diagnostic performance in the musculoskeletal setting, with a consequent improvement in patient treatment and management. PMID:20177987

  6. 3-T MRI safety assessments of magnetic dental attachments and castable magnetic alloys

    PubMed Central

    Miyata, K; Abe, Y; Ishii, T; Ishigami, T; Ohtani, K; Nagai, E; Ohyama, T; Umekawa, Y; Nakabayashi, S

    2015-01-01

    Objectives: To assess the safety of different magnetic dental attachments during 3-T MRI according to the American Society for Testing and Materials F2182-09 and F2052-06e1 standard testing methods and to develop a method to determine MRI compatibility by measuring magnetically induced torque. Methods: The temperature elevations, magnetically induced forces and torques of a ferromagnetic stainless steel keeper, a coping comprising a keeper and a cast magnetic alloy coping were measured on MRI systems. Results: The coping comprising a keeper demonstrated the maximum temperature increase (1.42 °C) for the whole-body-averaged specific absorption rate and was calculated as 2.1 W kg−1 with the saline phantom. All deflection angles exceeded 45°. The cast magnetic alloy coping had the greatest deflection force (0.33 N) during 3-T MRI and torque (1.015 mN m) during 0.3-T MRI. Conclusions: The tested devices showed minimal radiofrequency (RF)-induced heating in a 3-T MR environment, but the cast magnetic alloy coping showed a magnetically induced deflection force and torque approximately eight times that of the keepers. For safety, magnetic dental attachments should be inspected before and after MRI and large prostheses containing cast magnetic alloy should be removed. Although magnetic dental attachments may pose no great risk of RF-induced heating or magnetically induced torque during 3-T MRI, their magnetically induced deflection forces tended to exceed acceptable limits. Therefore, the inspection of such devices before and after MRI is important for patient safety. PMID:25785821

  7. Reference values of myocardial structure, function, and tissue composition by cardiac magnetic resonance in healthy African-Americans at 3T and their relations to serologic and cardiovascular risk factors.

    PubMed

    Liu, Chia-Ying; Bluemke, David A; Gerstenblith, Gary; Zimmerman, Stefan L; Li, Ji; Zhu, Hong; Lai, Shenghan; Lai, Hong

    2014-09-01

    Cardiac magnetic resonance (CMR) is a standard of reference for cardiac structure and function. Recent advances in T1 mapping and spectroscopy also provide assessment of myocardial tissue composition. However, the reference ranges of left ventricular parameters have rarely been assessed in an African-American (AA) population without known cardiac disease. To estimate the reference values of myocardial structure, function, and tissue composition by CMR and to explore their relationships to serologic factors and cardiovascular risk factors in asymptomatic AAs with low Framingham risk, between November 2010 and June 2012, 92 healthy AAs aged ≥21 years, from Baltimore, MD, were enrolled in an observational study. CMR examination was performed on a 3T scanner. Proton magnetic resonance spectroscopy was performed to noninvasively quantify myocardial triglyceride content. Native T1 values were obtained from modified Look-Locker inversion recovery sequence. The median age was 37 (interquartile range IQR 27 to 44) years (41% men). The median native T1 time of the myocardium was 1,228 ms (IQR 1,200 to 1,263) with no gender difference. The median myocardial fat content was 0.6% (IQR 0.7% to 4.6%). Native T1 time was not influenced by age, sex, and body mass index. Among the factors investigated, myocardial fat and elevated C-reactive protein (>2.0 mg/dL) were independently associated with T1 relaxation time. Native T1 time was also independently associated with left ventricular end-diastolic volume indexed to body surface area. In conclusion, this study of asymptomatic AAs provides reference ranges for cardiovascular structure, function, and tissue composition. Alterations in myocardial fat are associated with native T1 time, a CMR measure of interstitial fibrosis. PMID:25037675

  8. Philips 3T Intera Magnetic Resonance Imaging System and Upgrade of existing MRI equipment

    SciTech Connect

    Evanochko, William T

    2004-05-14

    The objective of this proposal was twofold. First, upgrade existing MRI equipment, specifically a research 4.1T whole-body system. Second, purchase a clinical, state-of-the-art 3T MRI system tailored specifically to cardiovascular and neurological applications. This project was within the guidelines of ''Medical Applications and Measurement Science''. The goals were: [1] to develop beneficial applications of magnetic resonance imaging; [2] discover new applications of MR strategies for medical research; and [2] apply them for clinical diagnosis. Much of this proposal searched for breakthroughs in this noninvasive and nondestructive imaging technology. Finally, this proposal's activities focused on research in the basic science of chemistry, biochemistry, physics, and engineering as applied to bioengineering. The centerpiece of this grant was our 4.1T ultra-high field whole-body nuclear magnetic resonance system and the newly acquired state-of-the-art, heart and head dedicated 3T clinical MRI system. We have successfully upgraded the equipment for the 4.1T system so that it is now state-of-the-art with new gradient and radio frequency amplifiers. We also purchase a unique In Vivo EKG monitoring unit that will permit tracking clinical quality EKG signals while the patient is in a high field MR scanner. Important upgrades of a peripheral vascular coil and a state-of-the-art clinical workstation for processing complex heart images were implemented. The most recent acquisition was the purchase of a state-of-the-art Philips 3T Intera clinical MRI system. This system is unique in that the magnet is only 5 1/2 feet long compare to over 12 feet long magnet of our 4.1T MRI system. The 3T MRI system is fully functional and its use and applications are already greatly benefiting the UAB with 200-300 micron resolution brain images and diagnostic quality MR angiography of coronary arteries in less than 5 minutes.

  9. Cardiovascular magnetic resonance imaging of isolated perfused pig hearts in a 3T clinical MR scanner

    PubMed Central

    Chiribiri, Amedeo; Ishida, Masaki; Morton, Geraint; Paul, Matthias; Hussain, Shazia T.; Bigalke, Boris; Perera, Divaka; Schaeffter, Tobias; Nagel, Eike

    2012-01-01

    Purpose An isolated perfused pig heart model has recently been proposed for the development of novel methods in standard clinical magnetic resonance (MR) scanners. The original set-up required the electrical system to be within the safe part of the MR-room, which introduced significant background noise. The purpose of the current work was to refine the system to overcome this limitation so that all electrical parts are completely outside the scanner room. Methods Four pig hearts were explanted under terminal anaesthesia from large white cross landrace pigs. All hearts underwent cardiovascular magnetic resonance (CMR) scanning in the MR part of a novel combined 3T MR and x-ray fluoroscopy (XMR) suite. CMR scanning included real-time k-t SENSE functional imaging, k-t SENSE accelerated perfusion imaging and late gadolinium enhancement imaging. Interference with image quality was assessed by spurious echo imaging and compared to noise levels acquired while operating the electrical parts within the scanner room. Results Imaging was performed successfully in all hearts. The system proved suitable for isolated heart perfusion in a novel 3T XMR suite. No significant additional noise was introduced into the scanner room by our set-up. Conclusions We have substantially improved a previous version of an isolated perfused pig heart model and made it applicable for MR imaging in a state of the art clinical 3T XMR imaging suite. The use of this system should aid novel CMR sequence development and translation into clinical practice. PMID:24265875

  10. Improved SNR of magnetic resonance microimaging using a cooled resonance circuit at 0.3T.

    PubMed

    Nakano, Hiroshi; Nakai, Toshiharu

    2011-01-01

    Because it is noninvasive, magnetic resonance microimaging (MRMI) can be used for 3-dimensional measurement of living tissues for cell engineering. Thermal noise in the resonance circuit of the radiofrequency (RF) system of the MRMI cannot become ignored as the signal diminishes in accordance with decreasing sample size, and cooling the RF coil of the receiver circuit can effectively reduce thermal noise. We used a low temperature normal conductor circuit to reduce noise and confirmed improved signal-to-noise ratio for a conventional microimaging system at low B(0) field (0.3T) with low cost. PMID:22214912

  11. Contributed Review: Nuclear magnetic resonance core analysis at 0.3 T

    SciTech Connect

    Mitchell, Jonathan Fordham, Edmund J.

    2014-11-15

    Nuclear magnetic resonance (NMR) provides a powerful toolbox for petrophysical characterization of reservoir core plugs and fluids in the laboratory. Previously, there has been considerable focus on low field magnet technology for well log calibration. Now there is renewed interest in the study of reservoir samples using stronger magnets to complement these standard NMR measurements. Here, the capabilities of an imaging magnet with a field strength of 0.3 T (corresponding to 12.9 MHz for proton) are reviewed in the context of reservoir core analysis. Quantitative estimates of porosity (saturation) and pore size distributions are obtained under favorable conditions (e.g., in carbonates), with the added advantage of multidimensional imaging, detection of lower gyromagnetic ratio nuclei, and short probe recovery times that make the system suitable for shale studies. Intermediate field instruments provide quantitative porosity maps of rock plugs that cannot be obtained using high field medical scanners due to the field-dependent susceptibility contrast in the porous medium. Example data are presented that highlight the potential applications of an intermediate field imaging instrument as a complement to low field instruments in core analysis and for materials science studies in general.

  12. An optically powered CMOS tracking system for 3 T magnetic resonance environment.

    PubMed

    Sarioglu, Baykal; Tumer, Murat; Cindemir, Umut; Camli, Berk; Dundar, Gunhan; Ozturk, Cengizhan; Yalcinkaya, Arda D

    2015-02-01

    In this work, a fully optical Complementary Metal Oxide Semiconductor (CMOS) based catheter tracking system designed for 3 T Magnetic Resonance Imaging (MRI) environment is presented. The system aims to solve the Radio Frequency (RF) induced heating problem present in conventional wired catheter tracking systems used in MRI. It is based on an integrated circuit, consisting of a receiver and an optical power supply unit. The optical power supply unit includes a single on-chip photodiode and a DC-DC converter that boosts the low photodiode voltage output to voltages greater than 1.5 V. Through an optically driven switch, the accumulated charge on an a storage capacitor is transferred to the rest of the system. This operation is novel in the way that it is fully optical and the switch control is done through modulation of the applied light. An on-chip local oscillator signal for the receiver is avoided by application of an RF signal that is generated by the MRI machine at the receiving period. The signals received by a micro-coil antenna are processed by the on-chip direct conversion receiver. The processed signal is then transferred, also optically, to the outside world for tracking purposes. The frequency encoding method is used for MRI tracking. Operation with various levels of external optical power does not generate noticeble temperature increase in the system. The overall system is successfully tested in a 3 T MRI machine to demonstrate its full operation. PMID:24893369

  13. Magnetic Levitation of MC3T3 Osteoblast Cells as a Ground-Based Simulation of Microgravity.

    PubMed

    Hammer, Bruce E; Kidder, Louis S; Williams, Philip C; Xu, Wayne Wenzhong

    2009-11-01

    Diamagnetic samples placed in a strong magnetic field and a magnetic field gradient experience a magnetic force. Stable magnetic levitation occurs when the magnetic force exactly counter balances the gravitational force. Under this condition, a diamagnetic sample is in a simulated microgravity environment. The purpose of this study is to explore if MC3T3-E1 osteoblastic cells can be grown in magnetically simulated hypo-g and hyper-g environments and determine if gene expression is differentially expressed under these conditions. The murine calvarial osteoblastic cell line, MC3T3-E1, grown on Cytodex-3 beads, were subjected to a net gravitational force of 0, 1 and 2 g in a 17 T superconducting magnet for 2 days. Microarray analysis of these cells indicated that gravitational stress leads to up and down regulation of hundreds of genes. The methodology of sustaining long-term magnetic levitation of biological systems are discussed. PMID:20052306

  14. Numerical study of remote detection outside the magnet with travelling wave Magnetic Resonance Imaging at 3T

    NASA Astrophysics Data System (ADS)

    López, M.; Vázquez, F.; Solís-Nájera, S.; Rodriguez, A. O.

    2015-01-01

    The use of the travelling wave approach for high magnetic field magnetic resonance imaging has been used recently with very promising results. This approach offer images one with greater field-of-view and a reasonable signal-to-noise ratio using a circular waveguide. This scheme has been proved to be successful at 7 T and 9.4 T with whole-body imager. Images have also been acquired with clinical magnetic resonance imaging systems whose resonant frequencies were 64 MHz and 128 MHz. These results motivated the use of remote detection of the magnetic resonance signal using a parallel-plate waveguide together with 3 T clinical scanners, to acquired human leg images. The cut-off frequency of this waveguide is zero for the principal mode, allowing us to overcome the barrier of transmitting waves at lower frequency than 300 MHz or 7 T for protons. These motivated the study of remote detection outside the actual magnet. We performed electromagnetic field simulations of a parallel-plate waveguide and a phantom. The signal transmission was done at 128 MHz and using a circular surface coil located almost 200 cm away for the magnet isocentre. Numerical simulations demonstrated that the magnetic field of the principal mode propagate inside a waveguide outside the magnet. Numerical results were compared with previous experimental-acquired image data under similar conditions.

  15. [Experimental evaluation of the occupational exposure to static magnetic fields on a 3 T magnetic resonance scanner].

    PubMed

    Moro, Luca; Alabiso, Francesco; Parisoli, Francesco; Frigerio, Francesco

    2013-01-01

    The recent postponement until 31 October 2013 of the deadline for transposition of the EU Directive 2004/40/EC, concerning the minimum health requirementsfor the exposure of workers to the risks arising from electromagnetic fields between 0 and 300 GHz, keeps on suspending the Italian law which was aimed to implement the EU regulations on the occupational exposure to electromagnetic fields, including those generated by Magnetic Resonance Imaging (MRI) units. Waiting for the revision of the exposure limits proposed by the EU Directive taking into account results from new studies and evolution of knowledge, the time-weighted values of static magnetic field proposed by the Italian Ministry of Health (D.M 02/08/91) still survive as limits for worker's exposure. The comparison between the proposed thresholds and the time required to position patients allows to calculate how long the MRI staff can stay at different values of static magnetic field, i.e. the maximum workload of each worker. In order to evaluate more accurately how many time the members of MRI staff are near the magnet bore and the real value of worker's exposure to the static magnetic field during the handling of patients, a teslameter Metrolab THM1176-PDA was used. Personal exposure measurements on the radiologists and the radiographers who worked on a 3 T GE Healthcare Discovery 750 MR were carried out during the positioning of self-sufficient and collaborative patients. The sensor was worn at the chest level on the side that was nearest to the magnet bore. Results show wide variations occurring between individual working procedures concerning the handling of patients, especially during the initial position phase. The mean values of the time spent by radiographers inside the magnet room (B > 0.5 mT) to place the patient and to take him outside at the end of the exam were respectively 220 and 127 seconds. The mean value of the time spent by radiologists was 162 seconds when they had to insert a peripheral

  16. Standardized quantitative measurements of wrist cartilage in healthy humans using 3T magnetic resonance imaging

    PubMed Central

    Zink, Jean-Vincent; Souteyrand, Philippe; Guis, Sandrine; Chagnaud, Christophe; Fur, Yann Le; Militianu, Daniela; Mattei, Jean-Pierre; Rozenbaum, Michael; Rosner, Itzhak; Guye, Maxime; Bernard, Monique; Bendahan, David

    2015-01-01

    AIM: To quantify the wrist cartilage cross-sectional area in humans from a 3D magnetic resonance imaging (MRI) dataset and to assess the corresponding reproducibility. METHODS: The study was conducted in 14 healthy volunteers (6 females and 8 males) between 30 and 58 years old and devoid of articular pain. Subjects were asked to lie down in the supine position with the right hand positioned above the pelvic region on top of a home-built rigid platform attached to the scanner bed. The wrist was wrapped with a flexible surface coil. MRI investigations were performed at 3T (Verio-Siemens) using volume interpolated breath hold examination (VIBE) and dual echo steady state (DESS) MRI sequences. Cartilage cross sectional area (CSA) was measured on a slice of interest selected from a 3D dataset of the entire carpus and metacarpal-phalangeal areas on the basis of anatomical criteria using conventional image processing radiology software. Cartilage cross-sectional areas between opposite bones in the carpal region were manually selected and quantified using a thresholding method. RESULTS: Cartilage CSA measurements performed on a selected predefined slice were 292.4 ± 39 mm2 using the VIBE sequence and slightly lower, 270.4 ± 50.6 mm2, with the DESS sequence. The inter (14.1%) and intra (2.4%) subject variability was similar for both MRI methods. The coefficients of variation computed for the repeated measurements were also comparable for the VIBE (2.4%) and the DESS (4.8%) sequences. The carpus length averaged over the group was 37.5 ± 2.8 mm with a 7.45% between-subjects coefficient of variation. Of note, wrist cartilage CSA measured with either the VIBE or the DESS sequences was linearly related to the carpal bone length. The variability between subjects was significantly reduced to 8.4% when the CSA was normalized with respect to the carpal bone length. CONCLUSION: The ratio between wrist cartilage CSA and carpal bone length is a highly reproducible standardized

  17. Technical challenges in 3 T magnetic resonance spectroscopic imaging of the prostate—A single-institution experience

    PubMed Central

    Underwood, Michelle; Boonsirikamchai, Piyaporn; Matin, Surena; Troncoso, Patricia; Ma, Jingfei

    2014-01-01

    The magnetic resonance spectroscopic imaging (MRSI) is the only technique that is currently available in the clinical practice to provide the metabolic status of prostate tissue at the cellular level with a great potential to improve the clinical patient care. Increasing the field strength from 1.5 to 3 T can theoretically provide proportionately higher signal-to-noise ratio (SNR) and improve spectral separation between prostatic metabolite peaks. The technique, however, has been limited to a few academic institutions that are equipped with a team of experts primarily due to due to serious technical challenges in optimizing the spectral quality. High quality shimming is key to the successful MRSI acquisition. Without optimization of the increased field inhomogeneity and radiofrequency (RF) dielectric effect at 3 T, the spectral peak broadening and residual signal from the periprostatic fat tissue may render the overall spectra non-diagnostic. The purpose of this technical note is to present the practical steps of successful acquisition of 3 T MRSI and to address several important technical challenges in minimizing the effect of the increased magnetic field and RF field inhomogeneity in order to obtain highest possible spectral quality based on our initial experience in using 3 T MRSI prototype software. PMID:25202660

  18. Technical challenges in 3 T magnetic resonance spectroscopic imaging of the prostate-A single-institution experience.

    PubMed

    Choi, Haesun; Underwood, Michelle; Boonsirikamchai, Piyaporn; Matin, Surena; Troncoso, Patricia; Ma, Jingfei

    2014-08-01

    The magnetic resonance spectroscopic imaging (MRSI) is the only technique that is currently available in the clinical practice to provide the metabolic status of prostate tissue at the cellular level with a great potential to improve the clinical patient care. Increasing the field strength from 1.5 to 3 T can theoretically provide proportionately higher signal-to-noise ratio (SNR) and improve spectral separation between prostatic metabolite peaks. The technique, however, has been limited to a few academic institutions that are equipped with a team of experts primarily due to due to serious technical challenges in optimizing the spectral quality. High quality shimming is key to the successful MRSI acquisition. Without optimization of the increased field inhomogeneity and radiofrequency (RF) dielectric effect at 3 T, the spectral peak broadening and residual signal from the periprostatic fat tissue may render the overall spectra non-diagnostic. The purpose of this technical note is to present the practical steps of successful acquisition of 3 T MRSI and to address several important technical challenges in minimizing the effect of the increased magnetic field and RF field inhomogeneity in order to obtain highest possible spectral quality based on our initial experience in using 3 T MRSI prototype software. PMID:25202660

  19. Resting state BOLD functional connectivity at 3T: spin echo versus gradient echo EPI.

    PubMed

    Chiacchiaretta, Piero; Ferretti, Antonio

    2015-01-01

    Previous evidence showed that, due to refocusing of static dephasing effects around large vessels, spin-echo (SE) BOLD signals offer an increased linearity and promptness with respect to gradient-echo (GE) acquisition, even at low field. These characteristics suggest that, despite the reduced sensitivity, SE fMRI might also provide a potential benefit when investigating spontaneous fluctuations of brain activity. However, there are no reports on the application of spin-echo fMRI for connectivity studies at low field. In this study we compared resting state functional connectivity as measured with GE and SE EPI sequences at 3T. Main results showed that, within subject, the GE sensitivity is overall larger with respect to that of SE, but to a less extent than previously reported for activation studies. Noteworthy, the reduced sensitivity of SE was counterbalanced by a reduced inter-subject variability, resulting in comparable group statistical connectivity maps for the two sequences. Furthermore, the SE method performed better in the ventral portion of the default mode network, a region affected by signal dropout in standard GE acquisition. Future studies should clarify if these features of the SE BOLD signal can be beneficial to distinguish subtle variations of functional connectivity across different populations and/or treatments when vascular confounds or regions affected by signal dropout can be a critical issue. PMID:25749359

  20. A 6.3 T Bend Magnet for the Advanced Light Source

    SciTech Connect

    Taylor, C.E.; Caspi, S.

    1995-06-07

    The Advanced Light Source (ALS) is a 1.5 to 1.9 GeV high-brightness electron storage ring operating at Lawrence Berkeley Laboratory (LBL) that provides synchrotron radiation for a large variety of users. It Is proposed to replace three of the thirty six 1.5T, one meter long bend magnets with very sbort high-field superconductlng (SC) dipoles. These magnets would provide bend-magnet synchrotron radiation to six bcamlines with a critical energy of at least 6 keV that is much better suited for protein crystallography and other small-sample x-ray diffraction and adsorption studies, than is currently available at the ALS. The magnet design is described, including coil, yoke, magnetic field analysis, and cyrostat. A prototype magnet is under construction at LBL.

  1. Window frame or ''superferric'' magnet design for low B(<3T) heavy ion storage ring study

    SciTech Connect

    Danby, G.; DeVito, B.; Jackson, J.; Keohane, G., Lee, Y.; Phillips, R.; Plate, S.; Repata, L.; Skaritka, J.; Smith, L.

    1985-01-01

    Double magnets share common laminations without magnetic coupling. Single layer coils of rectangular conductor are dry wound on extruded bore tubes. Magnet construction requires no molding or prestress. Absence of superconducting (SC) magnetization fields in the aperture results in very large dynamic range. The coil is wound continuously across the modplane to give unusually large dynamic aperture. Above approx.2.2 T saturation is corrected by simple sextupole windings with no inductive coupling to the dipole. Ultrastable design requires no internal quench protection. A quadrupole pair of novel design gives excellent field quality to B > 2 T without corrections, with no SC magnetization. Experience shows magnets are accurate enough for the assembly to take place at its final location. No training is required. Test procedures (measurements with search coils or with the beam) and cooldown properties are discussed. 2 refs., 8 figs., 1 tab.

  2. High-resolution In Vivo Manual Segmentation Protocol for Human Hippocampal Subfields Using 3T Magnetic Resonance Imaging.

    PubMed

    Winterburn, Julie; Pruessner, Jens C; Sofia, Chavez; Schira, Mark M; Lobaugh, Nancy J; Voineskos, Aristotle N; Chakravarty, M Mallar

    2015-01-01

    The human hippocampus has been broadly studied in the context of memory and normal brain function and its role in different neuropsychiatric disorders has been heavily studied. While many imaging studies treat the hippocampus as a single unitary neuroanatomical structure, it is, in fact, composed of several subfields that have a complex three-dimensional geometry. As such, it is known that these subfields perform specialized functions and are differentially affected through the course of different disease states. Magnetic resonance (MR) imaging can be used as a powerful tool to interrogate the morphology of the hippocampus and its subfields. Many groups use advanced imaging software and hardware (>3T) to image the subfields; however this type of technology may not be readily available in most research and clinical imaging centers. To address this need, this manuscript provides a detailed step-by-step protocol for segmenting the full anterior-posterior length of the hippocampus and its subfields: cornu ammonis (CA) 1, CA2/CA3, CA4/dentate gyrus (DG), strata radiatum/lacunosum/moleculare (SR/SL/SM), and subiculum. This protocol has been applied to five subjects (3F, 2M; age 29-57, avg. 37). Protocol reliability is assessed by resegmenting either the right or left hippocampus of each subject and computing the overlap using the Dice's kappa metric. Mean Dice's kappa (range) across the five subjects are: whole hippocampus, 0.91 (0.90-0.92); CA1, 0.78 (0.77-0.79); CA2/CA3, 0.64 (0.56-0.73); CA4/dentate gyrus, 0.83 (0.81-0.85); strata radiatum/lacunosum/moleculare, 0.71 (0.68-0.73); and subiculum 0.75 (0.72-0.78). The segmentation protocol presented here provides other laboratories with a reliable method to study the hippocampus and hippocampal subfields in vivo using commonly available MR tools. PMID:26575133

  3. A surface-tethered spheroid model for functional evaluation of 3T3-L1 adipocytes.

    PubMed

    Turner, Paul A; Harris, Lacey M; Purser, Christine A; Baker, Rodney C; Janorkar, Amol V

    2014-01-01

    In order to effectively treat obesity, it must be better understood at the cellular level with respect to metabolic state and environmental stress. However, current two-dimensional (2D) in vitro cell culture methods do not represent the in vivo adipose tissue appropriately due to the absence of complex architecture and cellular signaling. Conversely, 3D in vitro cultures have been reported to have optimal results mimicking the adipose tissue in vivo. The main aim of this study was to examine the efficacy of a novel conjugate of a genetically engineered polymer, elastin-like polypeptide (ELP) and a synthetic polymer, polyethyleneimine (PEI), toward creating a 3D preadipocyte culture system. We then used this 3D culture model to study the preadipocyte differentiation and adipocyte maintenance processes when subjected to various dosages of nutritionally relevant free fatty acids with respect to total DNA and protein content, cell viability, and intracellular triglyceride accumulation. Our results showed that 3T3-L1 preadipocytes cultured on the ELP-PEI surface formed 3D spheroids within 72 h, whereas the cells cultured on unmodified tissue culture polystyrene surfaces remained in monolayer configuration. Significant statistical differences were discovered between the 3D spheroid and 2D monolayer culture with respect to the DNA and protein content, fatty acid consumption, and triglyceride accumulation, indicating differences in cellular response. Results indicated that the 3D culture may be a more sensitive modeling technique for in vitro adipocyte culture and provides a platform for future evaluation of 3D in vitro adipocyte function. PMID:24038000

  4. Home-built magnetic resonance imaging system (0.3 T) with a complete digital spectrometer

    NASA Astrophysics Data System (ADS)

    Jie, Shen; Qin, Xu; Ying, Liu; Gengying, Li

    2005-10-01

    A home-built magnetic resonance imaging (MRI) system with a complete digital spectrometer has been designed for investigation of plants and animals. With the application of the latest digital integrated circuit technology, the digital spectrometer is greatly simplified without the loss of flexibility and performance. A powerful pulse sequence compiler with a graphical editor can allow the user to edit the pulse sequence more easily and more conveniently than ever before. Moreover, a permanent magnet capable of producing a 180 mm diam spherical homogeneous region is employed in our MRI system to ensure a comparatively large image size. Compared with previous work, our MRI system has the features of flexibility, relatively large imaging size, and low cost. Experimental results obtained with the proposed system are presented in this article.

  5. High resolution neurography of the lumbosacral plexus on 3T magneteic resonance imaging.

    PubMed

    Cejas, C; Escobar, I; Serra, M; Barroso, F

    2015-01-01

    Magnetic resonance neurography is a technique that complements clinical and electrophysiological study of the peripheral nerves and brachial and lumbosacral plexuses. Numerous focal processes (inflammatory, traumatic, primary tumors, secondary tumors) and diffuse processes (diabetic polyneuropathy, chronic idiopathic demyelinating polyneuropathy due to amyloidosis or Charcot-Marie-Tooth disease) can involve the lumbosacral plexus. This article reviews the anatomy of the lumbosacral plexus, describes the technique for neurography of the plexus at our institution, and shows the diverse diseases that affect it. PMID:25447367

  6. [Ovarian metastases from ventricular cancer diagnosed using diffusion-weighted 3T magnetic resonance imaging].

    PubMed

    Røhl, Lisbeth; Nellemann, Hanne Marie; Ladekarl, Morten; Pedersen, Erik Morre

    2011-04-18

    A 58-year-old female with a non-resectable ventricular cancer was followed by conventional 3.0 T magnetic resonance imaging (MRI) of the pelvis and abdomen including diffusion-weighted MR imaging (DWI). B-values were 0 and 1,000 seconds/mm2, and the apparent diffusion coefficient was calculated. At one control, ovarian metastases were detected by DWI, but did not show on conventional T2 and T1. The ovarian metastases were surgically removed and histologically verified - even though metastasectomy is controversial. In conclusion, DWI at 3.0 T is feasible and can improve the detection of metastatic disease compared with conventional MRI. PMID:21501566

  7. Long term effects of cocaine on the heart assessed by cardiovascular magnetic resonance at 3T

    PubMed Central

    2014-01-01

    Background Cocaine is an addictive, sympathomimetic drug with potentially lethal effects. The prevalence and features of cocaine cardiotoxicity are not well known. We aimed to assess these effects using a comprehensive cardiovascular magnetic resonance (CMR) protocol in a large group of asymptomatic cocaine users. Methods Consecutive (n = 94, 81 males, 36.6 ±7 years), non-selected, cocaine abusers were recruited and had a medical history, examination, ECG, blood test and CMR. The CMR study included measurement of left and right ventricular (LV, RV) dimensions and ejection fraction (EF), sequences for detection of myocardial oedema and late gadolinium enhancement (LGE). Images were compared to a cohort of healthy controls. Results Years of regular cocaine use were 13.9 ± 9. When compared to the age-matched healthy cohort, the cocaine abusers had increased LV end-systolic volume, LV mass index and RV end-systolic volume, with decreased LVEF and RVEF. No subject had myocardial oedema, but 30% had myocardial LGE indicating myocardial damage. Conclusions CMR detected cardiovascular disease in 71% of this cohort of consecutive asymptomatic cocaine abusers and mean duration of abuse was related to probability of LV systolic dysfunction. PMID:24758161

  8. Quantifiable Imaging Biomarkers for Evaluation of the Posterior Cruciate Ligament Using 3-T Magnetic Resonance Imaging

    PubMed Central

    Wilson, Katharine J.; Surowiec, Rachel K.; Ho, Charles P.; Devitt, Brian M.; Fripp, Jurgen; Smith, W. Sean; Spiegl, Ulrich J.; Dornan, Grant J.; LaPrade, Robert F.

    2016-01-01

    Background: Quantitative magnetic resonance imaging (MRI) techniques, such as T2 and T2 star (T2*) mapping, have been used to evaluate ligamentous tissue in vitro and to identify significant changes in structural integrity of a healing ligament. These studies lay the foundation for a clinical study that uses quantitative mapping to evaluate ligaments in vivo, particularly the posterior cruciate ligament (PCL). To establish quantitative mapping as a clinical tool for identifying and evaluating chronic or acute PCL injuries, T2 and T2* values first must be determined for an asymptomatic population. Purpose: To quantify T2 and T2* mapping properties, including texture variables (entropy, variance, contrast, homogeneity), of the PCL in an asymptomatic population. It was hypothesized that biomarker values would be consistent throughout the ligament, as measured across 3 clinically relevant subregions (proximal, middle, and distal thirds) in the asymptomatic cohort. Study Design: Cross-sectional study; Level of evidence, 4. Methods: Unilateral knee MRI scans were acquired for 25 asymptomatic subjects with a 3.0-T MRI system using T2 and T2* mapping sequences in the sagittal plane. The PCL was manually segmented and divided into thirds (proximal, middle, and distal). Summary statistics for T2 and T2* values were calculated. Intra- and interrater reliability was assessed across 3 raters to 2 time points. Results: The asymptomatic PCL cohort had mean T2 values of 36.7, 29.2, and 29.6 ms in the distal, middle, and proximal regions, respectively. The distal PCL exhibited significantly higher mean, variance, and contrast and lower homogeneity of T2 values than the middle and proximal subregions (P < .05). T2* results exhibited substantial positive skew and were therefore presented as median and quartile (Q) values. Median T2* values were 7.3 ms (Q1-Q3, 6.8-8.9 ms), 7.3 ms (Q1-Q3, 7.0-8.5 ms), and 7.3 ms (Q1-Q3, 6.4-8.2 ms) in the distal, middle, and proximal subregions

  9. 3T magnetic resonance neurography of pudendal nerve with cadaveric dissection correlation

    PubMed Central

    Chhabra, Avneesh; McKenna, Courtney A; Wadhwa, Vibhor; Thawait, Gaurav K; Carrino, John A; Lees, Gary P; Dellon, A Lee

    2016-01-01

    AIM To evaluate the pudendal nerve segments that could be identified on magnetic resonance neurography (MRN) before and after surgical marking of different nerve segments. METHODS The hypothesis for this study was that pudendal nerve and its branches would be more easily seen after the surgical nerve marking. Institutional board approval was obtained. One male and one female cadaver pelvis were obtained from the anatomy board and were scanned using 3 Tesla MRI scanner using MR neurography sequences. All possible pudendal nerve branches were identified. The cadavers were then sent to the autopsy lab and were surgically dissected by a peripheral nerve surgeon and an anatomist to identify the pudendal nerve branches. Radiological markers were placed along the course of the pudendal nerve and its branches. The cadavers were then closed and rescanned using the same MRN protocol as the pre-marking scan. The remaining pudendal nerve branches were attempted to be identified using the radiological markers. All scans were read by an experienced musculoskeletal radiologist. RESULTS The pre-marking MR Neurography scans clearly showed the pudendal nerve at its exit from the lumbosacral plexus in the sciatic notch, at the level of the ischial spine and in the Alcock’s Canal in both cadavers. Additionally, the right hemorrhoidal branch could be identified in the male pelvis cadaver. The perineal and distal genital branches could not be identified. On post-marking scans, the markers were used as identifiable structures. The location of the perineal branch, the hemorroidal branch and the dorsal nerve to penis (in male cadaver)/clitoris (in female cadaver) could be seen. However, the visualization of these branches was suboptimal. The contralateral corresponding nerves were poorly seen despite marking on the surgical side. The nerve was best seen on axial T1W and T2W SPAIR images. The proximal segment could be seen well on 3D DW PSIF sequence. T2W SPACE was not very useful in

  10. The potential of 3T high-resolution magnetic resonance imaging for diagnosis, staging, and follow-up of retinoblastoma.

    PubMed

    de Jong, Marcus C; de Graaf, Pim; Brisse, Hervé J; Galluzzi, Paolo; Göricke, Sophia L; Moll, Annette C; Munier, Francis L; Popovic, Maja Beck; Moulin, Alexandre P; Binaghi, Stefano; Castelijns, Jonas A; Maeder, Philippe

    2015-01-01

    We demonstrate the value of high-resolution magnetic resonance imaging (MRI) in diagnosing, staging, and follow-up of retinoblastoma during eye-saving treatment. We have included informative retinoblastoma cases scanned on a 3T MRI system from a retrospective retinoblastoma cohort from 2009 through 2013. We show that high-resolution MRI has the potential to detect small intraocular seeds, hemorrhage, and metastatic risk factors not visible with fundoscopy (e.g., optic nerve invasion and choroidal invasion), and treatment response. Unfortunately, however, the diagnostic accuracy of high-resolution MRI is not perfect, especially for subtle intraocular seeds or minimal postlaminar optic nerve invasion. The most important application of MRI is the detection of metastatic risk factors, as these cannot be found by fundoscopy and ultrasound. PMID:25891031

  11. Significant Artifact Reduction at 1.5T and 3T MRI by the Use of a Cochlear Implant with Removable Magnet: An Experimental Human Cadaver Study

    PubMed Central

    Wagner, Franca; Wimmer, Wilhelm; Leidolt, Lars; Vischer, Mattheus; Weder, Stefan; Wiest, Roland; Mantokoudis, Georgios; Caversaccio, Marco D.

    2015-01-01

    Objective Cochlear implants (CIs) are standard treatment for postlingually deafened individuals and prelingually deafened children. This human cadaver study evaluated diagnostic usefulness, image quality and artifacts in 1.5T and 3T magnetic resonance (MR) brain scans after CI with a removable magnet. Methods Three criteria (diagnostic usefulness, image quality, artifacts) were assessed at 1.5T and 3T in five cadaver heads with CI. The brain magnetic resonance scans were performed with and without the magnet in situ. The criteria were analyzed by two blinded neuroradiologists, with focus on image distortion and limitation of the diagnostic value of the acquired MR images. Results MR images with the magnet in situ were all compromised by artifacts caused by the CI. After removal of the magnet, MR scans showed an unequivocal artifact reduction with significant improvement of the image quality and diagnostic usefulness, both at 1.5T and 3T. Visibility of the brain stem, cerebellopontine angle, and parieto-occipital lobe ipsilateral to the CI increased significantly after magnet removal. Conclusions The results indicate the possible advantages for 1.5T and 3T MR scanning of the brain in CI carriers with removable magnets. Our findings support use of CIs with removable magnets, especially in patients with chronic intracranial pathologies. PMID:26200775

  12. Functional expression of 5-HT{sub 2A} receptor in osteoblastic MC3T3-E1 cells

    SciTech Connect

    Hirai, Takao; Kaneshige, Kota; Kurosaki, Teruko; Nishio, Hiroaki

    2010-05-28

    In the previous study, we reported the gene expression for proteins related to the function of 5-hydroxytryptamine (5-HT, serotonin) and elucidated the expression patterns of 5-HT{sub 2} receptor subtypes in mouse osteoblasts. In the present study, we evaluated the possible involvement of 5-HT receptor subtypes and its inactivation system in MC3T3-E1 cells, an osteoblast cell line. DOI, a 5-HT{sub 2A} and 5-HT{sub 2C} receptor selective agonist, as well as 5-HT concentration-dependently increased proliferative activities of MC3T3-E1 cells in their premature period. This effect of 5-HT on cell proliferation were inhibited by ketanserin, a 5-HT{sub 2A} receptor specific antagonist. Moreover, both DOI-induced cell proliferation and phosphorylation of ERK1 and 2 proteins were inhibited by PD98059 and U0126, selective inhibitors of MEK in a concentration-dependent manner. Furthermore, treatment with fluoxetine, a 5-HT specific re-uptake inhibitor which inactivate the function of extracellular 5-HT, significantly increased the proliferative activities of MC3T3-E1 cells in a concentration-dependent manner. Our data indicate that 5-HT fill the role for proliferation of osteoblast cells in their premature period. Notably, 5-HT{sub 2A} receptor may be functionally expressed to regulate mechanisms underlying osteoblast cell proliferation, at least in part, through activation of ERK/MAPK pathways in MC3T3-E1 cells.

  13. Classification of histologically scored human knee osteochondral plugs by quantitative analysis of magnetic resonance images at 3T.

    PubMed

    Lukas, Vanessa A; Fishbein, Kenneth W; Lin, Ping-Chang; Schär, Michael; Schneider, Erika; Neu, Corey P; Spencer, Richard G; Reiter, David A

    2015-05-01

    This work evaluates the ability of quantitative MRI to discriminate between normal and pathological human osteochondral plugs characterized by the Osteoarthritis Research Society International (OARSI) histological system. Normal and osteoarthritic human osteochondral plugs were scored using the OARSI histological system and imaged at 3 T using MRI sequences producing T1 and T2 contrast and measuring T1, T2, and T2* relaxation times, magnetization transfer, and diffusion. The classification accuracies of quantitative MRI parameters and corresponding weighted image intensities were evaluated. Classification models based on the Mahalanobis distance metric for each MRI measurement were trained and validated using leave-one-out cross-validation with plugs grouped according to OARSI histological grade and score. MRI measurements used for classification were performed using a region-of-interest analysis which included superficial, deep, and full-thickness cartilage. The best classifiers based on OARSI grade and score were T1- and T2-weighted image intensities, which yielded accuracies of 0.68 and 0.75, respectively. Classification accuracies using OARSI score-based group membership were generally higher when compared with grade-based group membership. MRI-based classification--either using quantitative MRI parameters or weighted image intensities--is able to detect early osteoarthritic tissue changes as classified by the OARSI histological system. These findings suggest the benefit of incorporating quantitative MRI acquisitions in a comprehensive clinical evaluation of OA. PMID:25641500

  14. HDAC5 controls the functions of Foxp3(+) T-regulatory and CD8(+) T cells.

    PubMed

    Xiao, Haiyan; Jiao, Jing; Wang, Liqing; O'Brien, Shaun; Newick, Kheng; Wang, Liang-Chuan S; Falkensammer, Eva; Liu, Yujie; Han, Rongxiang; Kapoor, Veena; Hansen, Finn K; Kurz, Thomas; Hancock, Wayne W; Beier, Ulf H

    2016-05-15

    Histone/protein deacetylases (HDACs) are frequently upregulated in human malignancies and have therefore become therapeutic targets in cancer therapy. However, inhibiting certain HDAC isoforms can have protolerogenic effects on the immune system, which could make it easier for tumor cells to evade the host immune system. Therefore, a better understanding of how each HDAC isoform affects immune biology is needed to develop targeted cancer therapy. Here, we studied the immune phenotype of HDAC5(-/-) mice on a C57BL/6 background. While HDAC5(-/-) mice replicate at expected Mendelian ratios and do not develop overt autoimmune disease, their T-regulatory (Treg) cells show reduced suppressive function in vitro and in vivo. Likewise, CD4(+) T-cells lacking HDAC5 convert poorly to Tregs under appropriately polarizing conditions. To test if this attenuated Treg formation and suppressive function translated into improved anticancer immunity, we inoculated HDAC5(-/-) mice and littermate controls with a lung adenocarcinoma cell line. Cumulatively, lack of HDAC5 did not lead to better anticancer immunity. We found that CD8(+) T cells missing HDAC5 had a reduced ability to produce the cytokine, IFN-γ, in vitro and in vivo, which may offset the benefit of weakened Treg function and formation. Taken together, targeting HDAC5 weakens suppressive function and de-novo induction of Tregs, but also reduces the ability of CD8(+) T cells to produce IFN-γ. PMID:26704363

  15. Pediatric whole-body magnetic resonance imaging: Intra-individual comparison of technical quality, artifacts, and fixed structure visibility at 1.5 and 3 T

    PubMed Central

    Mohan, Shyam; Moineddin, Rahim; Chavhan, Govind B

    2015-01-01

    Purpose: To compare whole-body magnetic resonance imaging (WBMRI) performed at 1.5 and 3 T for technical quality, artifacts, and visibility of selected fixed structures. Patients and Methods: 21 children who had WBMRI at both 1.5 and 3 T scanners within a relatively short interval (3-13 months; average-8.6 months) were included. The images were objectively compared with scores from 4 to 1 for five parameters including severity of artifacts; visibility of liver, vertebral column, and marrow in legs; and overall image quality. Inter-observer agreement was calculated using Kendall's coefficient of Concordance (W) and scores were compared using Signed Rank test. Results: There was substantial inter-observer agreement for all five categories at both field strengths. The difference between averages of mean scores of all five parameters for two field strengths was statistically significant (P < 0.05), indicating less artifact, better fixed structure visibility, and overall image quality at 1.5 T as compared to 3 T. However, scores at 3 T were also rated within a good range (around 3) indicating its feasibility for WBMRI in children. Conclusion: WBMRI at 1.5 T has significantly better image quality, fixed structure visibility, and fewer artifacts, as compared to WBMRI at 3 T in children. This difference is unlikely to significantly affect detection of pathology on 3 T WBMRI as the image quality score at 3 T was also within good range. PMID:26752815

  16. A distinct cation-sensing mechanism in MC3T3-E1 osteoblasts functionally related to the calcium receptor.

    PubMed

    Quarles, L D; Hartle, J E; Siddhanti, S R; Guo, R; Hinson, T K

    1997-03-01

    The presence of a cation-sensing mechanism in osteoblasts is suggested by the ability of specific cations to stimulate osteoblastic proliferation in culture and to induce de novo bone formation in some experimental models. Our study examines whether extracellular cations stimulate osteoblasts through the recently identified G protein-coupled calcium receptor (CaR). We found that CaR agonists, calcium (Ca2+), gadolinium (Gd3+), aluminum (Al3+), and neomycin, stimulated DNA synthesis in murine-derived MC3T3-E1 preosteoblasts, whereas magnesium (Mg2+), nickel (Ni2+), cadmium (Cd2+), and zinc (Zn2+) had no effect. With the exception of Mg2+, the cation specificities and apparent affinities were similar to that reported for CaR. CaR agonists also stimulated DNA synthesis in C3HT10(1/2) fibroblasts, but not in mesangial PVG, CHO, hepatic HTC, COS-7 cells, or malignant transformed ROS17/2.8 and UMR-106 osteoblasts. In addition, similar to other growth factors, CaR agonists activated transcription of a serum response element luciferase reporter construct (SRE-Luc) stably transfected into MC3T3-E1 osteoblasts, but had no effect on SRE-Luc transfected into CHO and COS-7 cells. We were unable to detect CaR expression by Northern analysis using a mouse CaR-specific probe or to amplify CaR mRNA by reverse transcribed polymerase chain reaction in MC3T3-E1 osteoblasts. These findings suggest that an extra-cellular cation-sensing mechanism is present in murine-derived osteoblasts that is functionally similar to but molecularly distinct from CaR. PMID:9076582

  17. Osteogenic differentiation of MC3T3-E1 cells on poly(L-lactide)/Fe3O4 nanofibers with static magnetic field exposure.

    PubMed

    Cai, Qing; Shi, Yuzhou; Shan, Dingying; Jia, Wenkai; Duan, Shun; Deng, Xuliang; Yang, Xiaoping

    2015-10-01

    Proliferation and differentiation of bone-related cells are modulated by many factors such as scaffold design, growth factor, dynamic culture system, and physical simulation. Nanofibrous structure and moderate-intensity (1 mT-1 T) static magnetic field (SMF) have been identified as capable of stimulating proliferation and differentiation of osteoblasts. Herein, magnetic nanofibers were prepared by electrospinning mixture solutions of poly(L-lactide) (PLLA) and ferromagnetic Fe3O4 nanoparticles (NPs). The PLLA/Fe3O4 composite nanofibers demonstrated homogeneous dispersion of Fe3O4 NPs, and their magnetism depended on the contents of Fe3O4 NPs. SMF of 100 mT was applied in the culture of MC3T3-E1 osteoblasts on pure PLLA and PLLA/Fe3O4 composite nanofibers for the purpose of studying the effect of SMF on osteogenic differentiation of osteoblastic cells on magnetic nanofibrous scaffolds. On non-magnetic PLLA nanofibers, the application of external SMF could enhance the proliferation and osteogenic differentiation of MC3T3-E1 cells. In comparison with pure PLLA nanofibers, the incorporation of Fe3O4 NPs could also promote the proliferation and osteogenic differentiation of MC3T3-E1 cells in the absence or presence of external SMF. The marriage of magnetic nanofibers and external SMF was found most effective in accelerating every aspect of biological behaviors of MC3T3-E1 osteoblasts. The findings demonstrated that the magnetic feature of substrate and microenvironment were applicable ways in regulating osteogenesis in bone tissue engineering. PMID:26117751

  18. Improve the image quality of orbital 3 T diffusion-weighted magnetic resonance imaging with readout-segmented echo-planar imaging.

    PubMed

    Xu, Xiao-Quan; Liu, Jun; Hu, Hao; Su, Guo-Yi; Zhang, Yu-Dong; Shi, Hai-Bin; Wu, Fei-Yun

    2016-01-01

    The aim of our study is to compare the image quality of readout-segmented echo-planar imaging (rs-EPI) and that of standard single-shot EPI (ss-EPI) in orbital 3 T diffusion-weighted (DW) magnetic resonance (MR) imaging in healthy subjects. Forty-two volunteers underwent two sets of orbital DW imaging scan at a 3 T MR unit, and image quality was assessed qualitatively and quantitatively. As a result, we found that rs-EPI could provide better image quality than standard ss-EPI, while no significant difference was found on the apparent diffusion coefficient between the two sets of DW images. PMID:27317226

  19. Functional Magnetic Resonance Imaging

    ERIC Educational Resources Information Center

    Voos, Avery; Pelphrey, Kevin

    2013-01-01

    Functional magnetic resonance imaging (fMRI), with its excellent spatial resolution and ability to visualize networks of neuroanatomical structures involved in complex information processing, has become the dominant technique for the study of brain function and its development. The accessibility of in-vivo pediatric brain-imaging techniques…

  20. Superconducting combined function magnets

    SciTech Connect

    Hahn, H.; Fernow, R.C.

    1983-01-01

    Superconducting accelerators and storage rings, presently under construction or in the design phase, are based on separate dipole and quadrupole magnets. It is here suggested that a hybrid lattice configuration consisting of dipoles and combined function gradient magnets would: (1) reduce the number of magnet units and their total cost; and (2) increase the filling factor and thus the energy at a given field. Coil cross sections are presented for the example of the Brookhaven Colliding Beam Accelerator. An asymmetric two-layer cable gradient magnet would have transfer functions of 10.42 G/A and 0.628 G cm/sup -1//A versus 15.77 G/A and 2.03 G cm/sup -1//A of the present separate dipoles and quadrupoles.

  1. Deoxyactein stimulates osteoblast function and inhibits bone-resorbing mediators in MC3T3-E1 cells.

    PubMed

    Choi, Eun Mi

    2013-03-01

    Osteoporosis is a systemic skeletal disease characterized by low bone mass and microarchitectural deterioration of bone tissue, with a consequent increase in bone fragility and susceptibility to fracture. In order to improve the treatment of osteoporosis, identification of anabolic agents with minimal side effects is highly desirable. Cimicifuga racemosa has a long and diverse history of medicinal use and deoxyactein isolated from this species is one of the major constituents. In the present study, the effect of deoxyactein on the function of osteoblastic MC3T3-E1 cells was studied. Deoxyactein caused a significant elevation of cell growth, alkaline phosphatase activity, collagen content, and mineralization in the cells (P < 0.05). Moreover, deoxyactein significantly (P < 0.05) decreased the production of reactive oxygen species (ROS) and osteoclast differentiation-inducing factors such as TNF-α, IL-6 and receptor activator of nuclear factor-κB ligand in the presence of antimycin A, which inhibits mitochondrial electron transport and has been used as an ROS generator. These results demonstrate that deoxyactein may have positive effects on skeletal structure. PMID:21910134

  2. Deltoid Ligament and Tibiofibular Syndesmosis Injury in Chronic Lateral Ankle Instability: Magnetic Resonance Imaging Evaluation at 3T and Comparison with Arthroscopy

    PubMed Central

    Chun, Ka-Young; Lee, Seok Hoon; Kim, Jin Su; Young, Ki Won; Jeong, Min-Sun; Kim, Dae-Jung

    2015-01-01

    Objective To evaluate the prevalence of deltoid ligament and distal tibiofibular syndesmosis injury on 3T magnetic resonance imaging (MRI) in patients with chronic lateral ankle instability (CLAI). Materials and Methods Fifty patients (mean age, 35 years) who had undergone preoperative 3T MRI and surgical treatment for CLAI were enrolled. The prevalence of deltoid ligament and syndesmosis injury were assessed. The complexity of lateral collateral ligament complex (LCLC) injury was correlated with prevalence of deltoid or syndesmosis injuries. The diagnostic accuracy of ankle ligament imaging at 3T MRI was analyzed using arthroscopy as a reference standard. Results On MRI, deltoid ligament injury was identified in 18 (36%) patients as follows: superficial ligament alone, 9 (50%); deep ligament alone 2 (11%); and both ligaments 7 (39%). Syndesmosis abnormality was found in 21 (42%) patients as follows: anterior inferior tibiofibular ligament (AITFL) alone, 19 (90%); and AITFL and interosseous ligament, 2 (10%). There was no correlation between LCLC injury complexity and the prevalence of an accompanying deltoid or syndesmosis injury on both MRI and arthroscopic findings. MRI sensitivity and specificity for detection of deltoid ligament injury were 84% and 93.5%, and those for detection of syndesmosis injury were 91% and 100%, respectively. Conclusion Deltoid ligament or syndesmosis injuries were common in patients undergoing surgery for CLAI, regardless of the LCLC injury complexity. 3T MRI is helpful for the detection of all types of ankle ligament injury. Therefore, careful interpretation of pre-operative MRI is essential. PMID:26356649

  3. Functional magnetic microspheres

    NASA Technical Reports Server (NTRS)

    Yen, Shiao-Ping S. (Inventor); Rembaum, Alan (Inventor); Landel, Robert F. (Inventor)

    1981-01-01

    Functional magnetic particles are formed by dissolving a mucopolysaccharide such as chitosan in acidified aqueous solution containing a mixture of ferrous chloride and ferric chloride. As the pH of the solution is raised magnetite is formed in situ in the solution by raising the pH. The dissolved chitosan is a polyelectrolyte and forms micelles surrounding the granules at pH of 8-9. The chitosan precipitates on the granules to form microspheres containing the magnetic granules. On addition of the microspheres to waste aqueous streams containing dissolved ions, the hydroxyl and amine functionality of the chitosan forms chelates binding heavy metal cations such as lead, copper, and mercury and the chelates in turn bind anions such as nitrate, fluoride, phosphate and borate.

  4. MO-G-18C-07: Improving T2 Determination and Quantification of Lipid Methylene Protons in Proton Magnetic Resonance Spectroscopy at 3 T

    SciTech Connect

    Breitkreutz, D.; Fallone, B. G.; Yahya, A.

    2014-06-15

    Purpose: To improve proton magnetic resonance spectroscopy (MRS) transverse relaxation (T{sub 2}) determination and quantification of lipid methylene chain (1.3 ppm) protons by rewinding their J-coupling evolution. Methods: MRS experiments were performed on four lipid phantoms, namely, almond, corn, sunflower and oleic acid, using a 3 T Philips MRI scanner with a transmit/receive birdcage head coil. Two PRESS (Point RESolved Spectroscopy) pulse sequences were used. The first PRESS sequence employed standard bandwidth (BW) (∼550 Hz) RF (radiofrequency) refocussing pulses, while the second used refocussing pulses of narrow BW (∼50 Hz) designed to rewind J-coupling evolution of the methylene protons in the voxel of interest. Signal was acquired with each sequence from a 5×5×5 mm{sup 3} voxel, with a repetition time (TR) of 3000 ms, and with echo times (TE) of 100 to 200 ms in steps of 20 ms. 2048 sample points were measured with a 2000 Hz sampling bandwidth. Additionally, 30 mm outer volume suppression slabs were used to suppress signal outside the voxel of interest. The frequency of the RF pulses was set to that of the methylene resonance. Methylene peak areas were calculated and fitted in MATLAB to a monexponentially decaying function of the form M{sub 0}exp(-TE/T{sub 2}), where M{sub 0} is the extrapolated area when TE = 0 ms and yields a measure of concentration. Results: The determined values of M{sub 0} and T{sub 2} increased for all fatty acids when using the PRESS sequence with narrow BW refocussing pulses. M{sub 0} and T{sub 2} values increased by an average amount (over all the phantoms) of 31% and 14%, respectively. Conclusion: This investigation has demonstrated that J-coupling interactions of lipid methylene protons causes non-negligible signal losses which, if not accounted for, Result in underestimations of their levels and T{sub 2} values when performing MRS measurements. Funded by the Natural Sciences and Engineering Research Council of Canada

  5. Functional magnetic resonance imaging.

    PubMed

    Buchbinder, Bradley R

    2016-01-01

    Functional magnetic resonance imaging (fMRI) maps the spatiotemporal distribution of neural activity in the brain under varying cognitive conditions. Since its inception in 1991, blood oxygen level-dependent (BOLD) fMRI has rapidly become a vital methodology in basic and applied neuroscience research. In the clinical realm, it has become an established tool for presurgical functional brain mapping. This chapter has three principal aims. First, we review key physiologic, biophysical, and methodologic principles that underlie BOLD fMRI, regardless of its particular area of application. These principles inform a nuanced interpretation of the BOLD fMRI signal, along with its neurophysiologic significance and pitfalls. Second, we illustrate the clinical application of task-based fMRI to presurgical motor, language, and memory mapping in patients with lesions near eloquent brain areas. Integration of BOLD fMRI and diffusion tensor white-matter tractography provides a road map for presurgical planning and intraoperative navigation that helps to maximize the extent of lesion resection while minimizing the risk of postoperative neurologic deficits. Finally, we highlight several basic principles of resting-state fMRI and its emerging translational clinical applications. Resting-state fMRI represents an important paradigm shift, focusing attention on functional connectivity within intrinsic cognitive networks. PMID:27432660

  6. A comparison of 3-T magnetic resonance imaging and computed tomography arthrography to identify structural cartilage defects of the fetlock joint in the horse.

    PubMed

    Hontoir, Fanny; Nisolle, Jean-François; Meurisse, Hubert; Simon, Vincent; Tallier, Max; Vanderstricht, Renaud; Antoine, Nadine; Piret, Joëlle; Clegg, Peter; Vandeweerd, Jean-Michel

    2014-01-01

    Articular cartilage defects are prevalent in metacarpo/metatarsophalangeal (MCP/MTP) joints of horses. The aim of this study was to determine and compare the sensitivity and specificity of 3-Tesla magnetic resonance imaging (3-T MRI) and computed tomography arthrography (CTA) to identify structural cartilage defects in the equine MCP/MTP joint. Forty distal cadaver limbs were imaged by CTA (after injection of contrast medium) and by 3-T MRI using specific sequences, namely, dual-echo in the steady-state (DESS), and sampling perfection with application-optimised contrast using different flip-angle evolutions (SPACE). Gross anatomy was used as the gold standard to evaluate sensitivity and specificity of both imaging techniques. CTA sensitivity and specificity were 0.82 and 0.96, respectively, and were significantly higher than those of MRI (0.41 and 0.93, respectively) in detecting overall cartilage defects (no defect vs. defect). The intra and inter-rater agreements were 0.96 and 0.92, respectively, and 0.82 and 0.88, respectively, for CT and MRI. The positive predictive value for MRI was low (0.57). CTA was considered a valuable tool for assessing cartilage defects in the MCP/MTP joint due to its short acquisition time, its specificity and sensitivity, and it was also more accurate than MRI. However, MRI permits assessment of soft tissues and subchondral bone and is a useful technique for joint evaluation, although clinicians should be aware of the limitations of this diagnostic technique, including reduced accuracy. PMID:24321368

  7. Enhancement of growth and osteogenic differentiation of MC3T3-E1 cells via facile surface functionalization of polylactide membrane with chitooligosaccharide based on polydopamine adhesive coating

    NASA Astrophysics Data System (ADS)

    Li, Huihua; Luo, Chuang; Luo, Binghong; Wen, Wei; Wang, Xiaoying; Ding, Shan; Zhou, Changren

    2016-01-01

    To develop a chitooligosaccharide(COS)-functionalized poly(D,L-lactide) (PDLLA) membrane to enhance growth and osteogenic differentiation of MC3T3-E1 cells, firstly a thin polydopamine (PDOPA) layer was adhered to the PDLLA membrane via the self-polymerization and strong adhesion behavior of dopamine. Subsequently, COS was immobilized covalently on the resultant PDLLA/PDOPA composite membrane by coupling with PDOPA active coating. The successful immobilization of the PDOPA and COS was confirmed by attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy and X-ray photoelectron spectroscopy (XPS). Scanning electronic microscopy (SEM) and atomic force microscopy (AFM) results indicated that the surface topography and roughness of the membranes were changed, and the root mean square increased from 0.613 nm to 6.96 and 7.12 nm, respectively after coating PDOPA and COS. Water contact angle and surface energy measurements revealed that the membrane hydrophilicity was remarkably improved by surface modification. In vitro cells culture results revealed that the PDOPA- and COS-functionalized surfaces showed a significant increase in MC3T3-E1 cells adhesion, proliferation, osteogenic differentiation and alkaline phosphate activity compared to the pristine PDLLA substrate. Furthermore the COS-functionalized PDLLA membrane was more effectively at enhancing osteoblast activity than the PDOPA-functionalized PDLLA membrane.

  8. Baicalein induces CD4+Foxp3+ T cells and enhances intestinal barrier function in a mouse model of food allergy

    PubMed Central

    Bae, Min-Jung; Shin, Hee Soon; See, Hye-Jeong; Jung, Sun Young; Kwon, Da-Ae; Shon, Dong-Hwa

    2016-01-01

    The incidence of food allergy, which is triggered by allergen permeation of the gastrointestinal tract followed by a T-helper (Th) 2-mediated immune response, has been increasing annually worldwide. We examined the effects of baicalein (5,6,7-trihydroxyflavone), a flavonoid from Scutellaria baicalensis used in oriental herbal medicine, on regulatory T (Treg) cell induction and intestinal barrier function through the regulation of tight junctions in a mouse model of food allergy. An allergic response was induced by oral challenge with ovalbumin, and the incidence of allergic symptoms and T cell-related activity in the mesenteric lymph nodes were analyzed with and without the presence of baicalein. Our results demonstrated that the administration of baicalein ameliorated the symptoms of food allergy and attenuated serum IgE and effector T cells. However, Treg-related factors were up-regulated by baicalein. Furthermore, baicalein was shown to enhance intestinal barrier function through the regulation of tight junctions. We also found that baicalein treatment induced the differentiation of Treg cells via aryl hydrocarbon receptors (AhRs). Thus, the action of baicalein as an agonist of AhR can induce Treg differentiation and enhance barrier function, suggesting that baicalein might serve as an effective immune regulator derived from foods for the treatment of food allergy. PMID:27561877

  9. Baicalein induces CD4(+)Foxp3(+) T cells and enhances intestinal barrier function in a mouse model of food allergy.

    PubMed

    Bae, Min-Jung; Shin, Hee Soon; See, Hye-Jeong; Jung, Sun Young; Kwon, Da-Ae; Shon, Dong-Hwa

    2016-01-01

    The incidence of food allergy, which is triggered by allergen permeation of the gastrointestinal tract followed by a T-helper (Th) 2-mediated immune response, has been increasing annually worldwide. We examined the effects of baicalein (5,6,7-trihydroxyflavone), a flavonoid from Scutellaria baicalensis used in oriental herbal medicine, on regulatory T (Treg) cell induction and intestinal barrier function through the regulation of tight junctions in a mouse model of food allergy. An allergic response was induced by oral challenge with ovalbumin, and the incidence of allergic symptoms and T cell-related activity in the mesenteric lymph nodes were analyzed with and without the presence of baicalein. Our results demonstrated that the administration of baicalein ameliorated the symptoms of food allergy and attenuated serum IgE and effector T cells. However, Treg-related factors were up-regulated by baicalein. Furthermore, baicalein was shown to enhance intestinal barrier function through the regulation of tight junctions. We also found that baicalein treatment induced the differentiation of Treg cells via aryl hydrocarbon receptors (AhRs). Thus, the action of baicalein as an agonist of AhR can induce Treg differentiation and enhance barrier function, suggesting that baicalein might serve as an effective immune regulator derived from foods for the treatment of food allergy. PMID:27561877

  10. Acoustic noise during functional magnetic resonance imaginga)

    PubMed Central

    Ravicz, Michael E.; Melcher, Jennifer R.; Kiang, Nelson Y.-S.

    2007-01-01

    Functional magnetic resonance imaging (fMRI) enables sites of brain activation to be localized in human subjects. For studies of the auditory system, acoustic noise generated during fMRI can interfere with assessments of this activation by introducing uncontrolled extraneous sounds. As a first step toward reducing the noise during fMRI, this paper describes the temporal and spectral characteristics of the noise present under typical fMRI study conditions for two imagers with different static magnetic field strengths. Peak noise levels were 123 and 138 dB re 20 μPa in a 1.5-tesla (T) and a 3-T imager, respectively. The noise spectrum (calculated over a 10-ms window coinciding with the highest-amplitude noise) showed a prominent maximum at 1 kHz for the 1.5-T imager (115 dB SPL) and at 1.4 kHz for the 3-T imager (131 dB SPL). The frequency content and timing of the most intense noise components indicated that the noise was primarily attributable to the readout gradients in the imaging pulse sequence. The noise persisted above background levels for 300-500 ms after gradient activity ceased, indicating that resonating structures in the imager or noise reverberating in the imager room were also factors. The gradient noise waveform was highly repeatable. In addition, the coolant pump for the imager’s permanent magnet and the room air handling system were sources of ongoing noise lower in both level and frequency than gradient coil noise. Knowledge of the sources and characteristics of the noise enabled the examination of general approaches to noise control that could be applied to reduce the unwanted noise during fMRI sessions. PMID:11051496

  11. Repeatability of Quantitative Sodium Magnetic Resonance Imaging for Estimating Pseudo-Intracellular Sodium Concentration and Pseudo-Extracellular Volume Fraction in Brain at 3 T

    PubMed Central

    Madelin, Guillaume; Babb, James; Xia, Ding; Regatte, Ravinder R.

    2015-01-01

    The purpose of this study is to assess the repeatability of the quantification of pseudo-intracellular sodium concentration (C1) and pseudo-extracellular volume fraction (α) estimated in brain in vivo using sodium magnetic resonance (MRI) at 3 T. Eleven healthy subjects were scanned twice, with two sodium MRI acquisitions (with and without fluid suppression by inversion recovery), and two double inversion recovery (DIR) proton MRI. DIR MRIs were used to create masks of gray and white matter (GM, WM), that were subsequently applied to the C1 and α maps calculated from sodium MRI and a tissue three-compartment model, in order to measure the distributions of these two parameters in GM, WM or full brain (GM+WM) separately. The mean, median, mode, standard deviation (std), skewness and kurtosis of the C1 and α distributions in whole GM, WM and full brain were calculated for each subject, averaged over all data, and used as parameters for the repeatability assessment. The coefficient of variation (CV) was calculated as a measure of reliability for the detection of intra-subject changes in C1 and αfor each parameter, while intraclass correlation (ICC) was used as a measure of repeatability. It was found that the CV of most of the parameters was around 10–20% (except for C1 kurtosis which is about 40%) for C1 and α measurements, and that ICC was moderate to very good (0.4 to 0.9) for C1 parameters and for some of the α parameters (mainly skewness and kurtosis). In conclusion, the proposed method could allow to reliably detect changes of 50% and above of the different measurement parameters of C1 and αin neuropathologies (multiple sclerosis, tumor, stroke, Alzheimer’s disease) compared to healthy subjects, and that skewness and kurtosis of the distributions of C1 and αseem to be the more sensitive parameters to these changes. PMID:25751272

  12. A trapped magnetic field of 3 T in homogeneous, bulk MgB2 superconductors fabricated by a modified precursor infiltration and growth process

    NASA Astrophysics Data System (ADS)

    Bhagurkar, A. G.; Yamamoto, A.; Anguilano, L.; Dennis, A. R.; Durrell, J. H.; Babu, N. Hari; Cardwell, D. A.

    2016-03-01

    The wetting of boron with liquid magnesium is a critical factor in the synthesis of MgB2 bulk superconductors by the infiltration and growth (IG) process. Poor wetting characteristics can therefore result potentially in non-uniform infiltration, formation of defects in the final sample structure and poor structural homogeneity throughout the bulk material. Here we report the fabrication of near-net-shaped MgB2 bulk superconductors by a modified precursor infiltration and growth (MPIG) technique. A homogeneous bulk microstructure has subsequently been achieved via the uniform infiltration of Mg liquid by enriching pre-reacted MgB2 powder within the green precursor pellet as a wetting enhancer, leading to relatively little variation in superconducting properties across the entire bulk sample. Almost identical values of trapped magnetic field of 2.12 T have been measured at 5 K at both the top and bottom surfaces of a sample fabricated by the MPIG process, confirming the uniformity of the bulk microstructure. A maximum trapped field of 3 T has been measured at 5 K at the centre of a stack of two bulk MgB2 samples fabricated using this technique. A steady rise in trapped field was observed for this material with decreasing temperature down to 5 K without the occurrence of flux avalanches and with a relatively low field decay rate (1.5%/d). These properties are attributed to the presence of a fine distribution of residual Mg within the bulk microstructure generated by the MPIG processing technique.

  13. Clinical 3T MR imaging: mastering the challenges.

    PubMed

    Tanenbaum, Lawrence N

    2006-02-01

    3T MRI is ready to meet the needs of clinical practice. SAR limitations are minimized by technical advances and surface coils are available for all core applications. With appropriate adjustments to scanning protocols, one can master the challenges of scanning at 3T; studies of the brain, spine, chest, abdomen, pelvis, vasculature, and extremities can be consistently higher in quality than are those obtained at 1.5T. The superior studies that are obtainable at 3T have great appeal to clinicians who are sophisticated about MR technology in areas, such as neurology, orthopedics, vascular surgery, and oncology,and encourage a shift in referrals toward practices that invest in higher field technology. The greater sensitivity to magnetic susceptibility offers unique benefits in functional neuroimaging, and available software/hardware packages enhance clinical setting feasibility, which adds a source of new referrals. The greater overall signal of 3T can be manipulated to make scanning more comfortable and with less motion artifact because scan times could be half as long. Spectacular anatomic delineation that is provided by high-definition scanning at true 1024 resolution can improve preoperative assessment and may improve sensitivity to smaller lesions. 3T provides practices with an advantage that is sought increasingly by high field strength purchasers in a competitive market. Only cost considerations stand in the way of the eventual domination of 3T systems in the high field strength market. PMID:16530631

  14. Proliferation and function of MC3T3-E1 cells on freeze-cast hydroxyapatite scaffolds with oriented pore architectures.

    PubMed

    Fu, Qiang; Rahaman, Mohamed N; Bal, B Sonny; Brown, Roger F

    2009-05-01

    Previous work by the authors showed that hydroxyapatite (HA) scaffolds with different types of oriented microstructures and a unique 'elastic-plastic' mechanical response could be prepared by unidirectional freezing of suspensions. The objective of the present work was to evaluate the in vitro cellular response to these freeze-cast HA scaffolds. Unidirectional scaffolds with approximately the same porosity (65-70%) but different pore architectures, described as 'lamellar' (pore width = 25 +/- 5 microm) and 'cellular' (pore diameter = 100 +/- 10 microm), were evaluated. Whereas both groups of scaffolds showed excellent ability to support the proliferation of MC3T3-E1 pre-osteoblastic cells on their surfaces, scaffolds with the cellular-type microstructure showed far better ability to support cell proliferation into the pores and cell function. These results indicate that freeze-cast HA scaffolds with the cellular-type microstructure have better potential for bone repair applications. PMID:19115092

  15. Magnetic Beads Enhance Adhesion of NIH 3T3 Fibroblasts: A Proof-of-Principle In Vitro Study for Implant-Mediated Long-Term Drug Delivery to the Inner Ear

    PubMed Central

    Aliuos, Pooyan; Schulze, Jennifer; Schomaker, Markus; Reuter, Günter; Stolle, Stefan R. O.; Werner, Darja; Ripken, Tammo; Lenarz, Thomas; Warnecke, Athanasia

    2016-01-01

    Introduction Long-term drug delivery to the inner ear may be achieved by functionalizing cochlear implant (CI) electrodes with cells providing neuroprotective factors. However, effective strategies in order to coat implant surfaces with cells need to be developed. Our vision is to make benefit of electromagnetic field attracting forces generated by CI electrodes to bind BDNF-secreting cells that are labelled with magnetic beads (MB) onto the electrode surfaces. Thus, the effect of MB-labelling on cell viability and BDNF production were investigated. Materials and Methods Murine NIH 3T3 fibroblasts—genetically modified to produce BDNF—were labelled with MB. Results Atomic force and bright field microscopy illustrated the internalization of MB by fibroblasts after 24 h of cultivation. Labelling cells with MB did not expose cytotoxic effects on fibroblasts and allowed adhesion on magnetic surfaces with sufficient BDNF release. Discussion Our data demonstrate a novel approach for mediating enhanced long-term adhesion of BDNF-secreting fibroblasts on model electrode surfaces for cell-based drug delivery applications in vitro and in vivo. This therapeutic strategy, once transferred to cells suitable for clinical application, may allow the biological modifications of CI surfaces with cells releasing neurotrophic or other factors of interest. PMID:26918945

  16. Memory functions of magnetic skyrmions

    NASA Astrophysics Data System (ADS)

    Koshibae, Wataru; Kaneko, Yoshio; Iwasaki, Junichi; Kawasaki, Masashi; Tokura, Yoshinori; Nagaosa, Naoto

    2015-05-01

    We study, by microsimulation on the chiral magnets, the elementary functions of magnetic skyrmions and the design principles of skyrmionic memory devices. The external stimuli, such as local heating, magnetic field, electric field and electric current, trigger the creation and annihilation of the skyrmion. These procedures, corresponding to the writing and erasing operations, are achieved typically within of the order of nano or pico seconds. We also examine the current driven motion of the skyrmions and find that the gyro-dynamics, which is induced by the topological nature of the skyrmion, leads to the variety of useful functions including the remarkable enhancement of the spin-transfer-torque effect. These features are shown to be advantageous for (a) high-density data-storage, (b) nonvolatile memory, and (c) ultra-low current and energy cost manipulation.

  17. Magnetic Wood Achieving a Harmony between Magnetic and Woody Functions

    NASA Astrophysics Data System (ADS)

    Oka, Hideo

    Magnetic wood, which was first introduced and developed by the Oka group in 1991, achieves a good balance of both woody and magnetic functions through the active addition of magnetic characteristics to the wood itself. In addition to showing magnetic characteristics, this magnetic wood also offers a woody texture, low specific gravity, humidity control, acoustic absorption and is very easy to process.

  18. New-Generation Laser-lithographed Dual-Axis Magnetically Assisted Remote-controlled Endovascular Catheter for Interventional MR Imaging: In Vitro Multiplanar Navigation at 1.5 T and 3 T versus X-ray Fluoroscopy

    PubMed Central

    Moftakhar, Parham; Lillaney, Prasheel; Losey, Aaron D.; Cooke, Daniel L.; Martin, Alastair J.; Thorne, Bradford R. H.; Arenson, Ronald L.; Saeed, Maythem; Wilson, Mark W.

    2015-01-01

    Purpose To assess the feasibility of multiplanar vascular navigation with a new magnetically assisted remote-controlled (MARC) catheter with real-time magnetic resonance (MR) imaging at 1.5 T and 3 T and to compare it with standard x-ray guidance in simulated endovascular catheterization procedures. Materials and Methods A 1.6-mm–diameter custom clinical-grade microcatheter prototype with lithographed double-saddle coils at the distal tip was deflected with real-time MR imaging. Two inexperienced operators and two experienced operators catheterized anteroposterior (celiac, superior mesenteric, and inferior mesenteric arteries) and mediolateral (renal arteries) branch vessels in a cryogel abdominal aortic phantom. This was repeated with conventional x-ray fluoroscopy by using clinical catheters and guidewires. Mean procedure times and percentage success data were analyzed with linear mixed-effects regression. Results The MARC catheter tip was visible at 1.5 T and 3 T. Among inexperienced operators, MARC MR imaging guidance was not statistically different from x-ray guidance at 1.5 T (67% successful vessel selection turns with MR imaging vs 76% with x-ray guidance, P = .157) and at 3 T (75% successful turns with MR imaging vs 76% with x-ray guidance, P = .869). Experienced operators were more successful in catheterizing vessels with x-ray guidance (98% success within 60 seconds) than with 1.5-T (65%, P < .001) or 3-T (75%) MR imaging. Among inexperienced operators, mean procedure time was nearly equivalent by using MR imaging (31 seconds) and x-ray guidance (34 seconds, P = .436). Among experienced operators, catheterization was faster with x-ray guidance (20 seconds) compared with 1.5-T MR imaging (42 seconds, P < .001), but MARC guidance improved at 3 T (31 seconds). MARC MR imaging guidance at 3 T was not significantly different from x-ray guidance for the celiac (P = .755), superior mesenteric (P = .358), and inferior mesenteric (P = .065) arteries. Conclusion

  19. Functional proteomic analysis of long-term growth factor stimulation and receptor tyrosine kinase coactivation in Swiss 3T3 fibroblasts.

    PubMed

    Nagano, Kohji; Akpan, Akunna; Warnasuriya, Gayathri; Corless, Steven; Totty, Nick; Yang, Alice; Stein, Robert; Zvelebil, Marketa; Stensballe, Allan; Burlingame, Al; Waterfield, Michael; Cramer, Rainer; Timms, John F; Naaby-Hansen, Søren

    2012-12-01

    In Swiss 3T3 fibroblasts, long-term stimulation with PDGF, but not insulin-like growth factor 1 (IGF-1) or EGF, results in the establishment of an elongated migratory phenotype, characterized by the formation of retractile dendritic protrusions and absence of actin stress fibers and focal adhesion complexes. To identify receptor tyrosine kinase-specific reorganization of the Swiss 3T3 proteome during phenotypic differentiation, we compared changes in the pattern of protein synthesis and phosphorylation during long-term exposure to PDGF, IGF-1, EGF, and their combinations using 2DE-based proteomics after (35)S- and (33)P-metabolic labeling. One hundred and five differentially regulated proteins were identified by mass spectrometry and some of these extensively validated. PDGF stimulation produced the highest overall rate of protein synthesis at any given time and induced the most sustained phospho-signaling. Simultaneous activation with two or three of the growth factors revealed both synergistic and antagonistic effects on protein synthesis and expression levels with PDGF showing dominance over both IGF-1 and EGF in generating distinct proteome compositions. Using signaling pathway inhibitors, PI3K was identified as an early site for signal diversification, with sustained activity of the PI3K/AKT pathway critical for regulating late protein synthesis and phosphorylation of target proteins and required for maintaining the PDGF-dependent motile phenotype. Several proteins were identified with novel PI3K/Akt-dependent synthesis and phosphorylations including eEF2, PRS7, RACK-1, acidic calponin, NAP1L1, Hsp73, and fascin. The data also reveal induction/suppression of key F-actin and actomyosin regulators and chaperonins that enable PDGFR to direct the assembly of a motile cytoskeleton, despite simultaneous antagonistic signaling activities. Together, the study demonstrates that long-term exposure to different growth factors results in receptor tyrosine kinase

  20. [G3T]5/Tb(3+) based DNA biosensor with target DNA-triggered autocatalytic multi-cycle-amplification and magnetic nanoparticles assisted-background-lowered.

    PubMed

    Jiang, Hong; Zhang, Xiaojun; Wang, Guangfeng

    2015-12-15

    Due to terbium's unique photophysical properties, nucleic-acid-sensitized terbium (DNA/Tb(3+)) bioluminescent system becomes a potential candidate for the fabrication of DNA biosensors. However, the low sensitivity of DNA/Tb(3+) bioluminescent system limits its development. In this paper, a strategy combining autocatalytic multi-cycle-amplification (including exonuclease III (exo III)-aided and Zn(2+)-requiring DNAzyme-assisted target recycling amplifications) and magnetic nanoparticles assisted-background-lowering to improve the sensitivity of DNA/Tb(3+) bioluminescent system is presented for sensitive detection of target DNA (tDNA). The DNA/Tb(3+) bioluminescent system was investigated by ultraviolet-visible (UV-vis) absorption and luminescence spectra. The possible conjugation mechanism and mode of DNA with Tb(3+) were discussed. The autocatalytic multi-cycle-amplification effect was investigated by the comparison of the luminescence. The carboxylation-functionalized Fe3O4-magnetic nanoparticles (MNPs) were characterized and its role in background lowering was proved. As a result, with the designed protocol, the detection limit for the tDNA detection reached a low level to aM, which is especially exciting for the DNA/Tb(3+) bioluminescent system. In the process, due to the separation effect of MNPs, the assay solution was purified to avoid the nonspecific luminescence of DNA/Tb(3+), not only lowering the background signal greatly (about five times lower than that without the use of MNPs but also improving the reproducibility and stability. We hope that our attempt in this field will not only extend the application of DNA/Tb(3+) luminescent system in biosensing areas but also open the road to adaptation of the protocols to other related analytes. PMID:26257185

  1. Epoxyeicosatrienoic Acids Regulate Adipocyte Differentiation of Mouse 3T3 Cells, Via PGC-1α Activation, Which Is Required for HO-1 Expression and Increased Mitochondrial Function.

    PubMed

    Waldman, Maayan; Bellner, Lars; Vanella, Luca; Schragenheim, Joseph; Sodhi, Komal; Singh, Shailendra P; Lin, Daohong; Lakhkar, Anand; Li, Jiangwei; Hochhauser, Edith; Arad, Michael; Darzynkiewicz, Zbigniew; Kappas, Atallah; Abraham, Nader G

    2016-07-15

    Epoxyeicosatrienoic acid (EET) contributes to browning of white adipose stem cells to ameliorate obesity/diabetes and insulin resistance. In the current study, we show that EET altered preadipocyte function, enhanced peroxisome proliferation-activated receptor γ coactivator α (PGC-1α) expression, and increased mitochondrial function in the 3T3-L1 preadipocyte subjected to adipogenesis. Cells treated with EET resulted in an increase, P < 0.05, in PGC-1α and a decrease in mitochondria-derived ROS (MitoSox), P < 0.05. The EET increase in heme oxygenase-1 (HO-1) levels is dependent on activation of PGC-1α as cells deficient in PGC-1α (PGC-1α knockout adipocyte cell) have an impaired ability to express HO-1, P < 0.02. Additionally, adipocytes treated with EET exhibited an increase in mitochondrial superoxide dismutase (SOD) in a PGC-1α-dependent manner, P < 0.05. The increase in PGC-1α was associated with an increase in β-catenin, P < 0.05, adiponectin expression, P < 0.05, and lipid accumulation, P < 0.02. EET decreased heme levels and mitochondria-derived ROS (MitoSox), P < 0.05, compared to adipocytes that were untreated. EET also decreased mesoderm-specific transcript (MEST) mRNA and protein levels (P < 0.05). Adipocyte secretion of EET act in an autocrine/paracrine manner to increase PGC-1α is required for activation of HO-1 expression. This is the first study to dissect the mechanism by which the antiadipogenic and anti-inflammatory lipid, EET, induces the PGC-1α signaling cascade and reprograms the adipocyte phenotype by regulating mitochondrial function and HO-1 expression, leading to an increase in healthy, that is, small, adipocytes and a decrease in adipocyte enlargement and terminal differentiation. This is manifested by an increase in mitochondrial function and an increase in the canonical Wnt signaling cascade during adipocyte proliferation and terminal differentiation. PMID:27224420

  2. Prediction of the efficacy of surgical intervention in patients with cervical myelopathy by using diffusion tensor 3T-magnetic resonance imaging parameters

    PubMed Central

    Arima, Hironori; Sakamoto, Shinichi; Naito, Kentaro; Yamagata, Toru; Uda, Takehiro; Ohata, Kenji; Takami, Toshihiro

    2015-01-01

    Background: The clinical significance of diffusion tensor (DT) magnetic resonance imaging (MRI) parameters was analyzed to predict postoperative functional recovery in patients with cervical myelopathy. Materials and Methods: Sixteen patients with cervical myelopathy caused by cervical spondylosis, disk herniation or ossification of the posterior longitudinal ligament who underwent surgical intervention in our institute were enrolled in this retrospective study. There were 7 men and 9 women, with a mean age of 62.8 years. Clinical assessment was done before surgery and at least 3 months after surgery. All patients underwent whole-body 3.0-Tesla MRI before surgery. DT images (DTIs) were obtained using a single-shot fast spin-echo-based sequence. Mean values of mean diffusivity (MD) and fractional anisotropy (FA) at 6 disk levels of the cervical spine were measured using manual setting of regions of interest. The MD and FA values at the most compressed part were analyzed. Absolute MD and FA values at the most compressed spinal level in patients were transformed into the normalized values with a z-score analysis. Results: MD-z may decrease with the severity of cervical myelopathy. Receiver operating characteristic analysis of MD-z and FA-z suggested that both MD-z and FA-z have clinical validity for predicting the efficacy of surgical intervention, but MD-z was considered to be the most appropriate value to predict the efficacy of surgery. Conclusions: DTIs may be a promising modality to predict functional recovery after surgery. MD changes may reflect spinal cord condition and its reversibility. PMID:26288547

  3. Scaffold-free formation of a millimeter-scale multicellular spheroid with an internal cavity from magnetically levitated 3T3 cells that ingested iron oxide-containing microspheres.

    PubMed

    Lee, Joon Ho; Hur, Won

    2014-05-01

    This report describes fabrication of a millimeter-scale three-dimensional (3D) multicellular structure with a central cavity based on magnetic levitation of 3T3 cells that had ingested Fe3 O4 -containing microcapsules. Magnetically levitated cells initially formed a disc-shaped cell cluster at the air-medium interface and transformed into a spheroid (up to 2.8 mm in diameter) after 10-day incubation under a magnet. Hematoxylin-and-eosin-stained section revealed that an eosinophilic shell of cells enclosed a pale-staining core of the spheroid. Mitotic or elongated and aligned cells were found at the outer periphery of the shell, while Fe3 O4 deposits were distributed in the inner part of the shell. Surgical dissection indicated that the spheroid had a hollow interior filled with a fluid-state cell suspension. Accordingly, it was demonstrated that magnetically levitated 3T3 cells organized themselves into a tissue-like spheroid, resulting in core cell death. The spheroid can be used as a 3D tissue model and as building blocks that fused to form a more complicated structure. PMID:24254251

  4. Functional Magnetic Resonance Imaging Methods

    PubMed Central

    Chen, Jingyuan E.; Glover, Gary H.

    2015-01-01

    Since its inception in 1992, Functional Magnetic Resonance Imaging (fMRI) has become an indispensible tool for studying cognition in both the healthy and dysfunctional brain. FMRI monitors changes in the oxygenation of brain tissue resulting from altered metabolism consequent to a task-based evoked neural response or from spontaneous fluctuations in neural activity in the absence of conscious mentation (the “resting state”). Task-based studies have revealed neural correlates of a large number of important cognitive processes, while fMRI studies performed in the resting state have demonstrated brain-wide networks that result from brain regions with synchronized, apparently spontaneous activity. In this article, we review the methods used to acquire and analyze fMRI signals. PMID:26248581

  5. Tubby-like protein superfamily member PLSCR3 functions as a negative regulator of adipogenesis in mouse 3T3-L1 preadipocytes by suppressing induction of late differentiation stage transcription factors.

    PubMed

    Inokawa, Akira; Inuzuka, Tatsutoshi; Takahara, Terunao; Shibata, Hideki; Maki, Masatoshi

    2016-01-01

    PLSCR3 (phospholipid scramblase 3, Scr3) belongs to the superfamily of membrane-associated transcription regulators named Tubby-like proteins (TULPs). Physiological phospholipid scrambling activities of PLSCRs in vivo have been skeptically argued, and knowledge of the biological functions of Scr3 is limited. We investigated the expression of Scr3 during differentiation of mouse 3T3-L1 preadipocytes by Western blotting (WB) and by reverse-transcription and real-time quantitative PCR (RT-qPCR). The Scr3 protein decreased during 3T3-L1 differentiation accompanied by a reduction in the mRNA level, and there was a significant increase in the amount of Scr3 protein secreted into the culture medium in the form of extracellular microvesicles (exosomes). On the other hand, Scr3 expression did not significantly decrease, and the secretion of Scr3 in 3T3 Swiss-albino fibroblasts (a parental cell-line of 3T3-L1) was not increased by differentiation treatment. Overexpression of human Scr3 during 3T3-L1 differentiation suppressed triacylglycerol accumulation and inhibited induction of the mRNAs of late stage pro-adipogenic transcription factors [CCAAT/enhancer-binding protein α (C/EBPα) and peroxisome proliferator-activated receptor γ (PPARγ)] and X-box-binding protein 1 (XBP1). Expression of early stage pro-adipogenic transcription factors (C/EBPβ and C/EBPδ) was not significantly affected. These results suggest that Scr3 functions as a negative regulator of adipogenesis in 3T3-L1 cells at a specific differentiation stage and that decrease in the intracellular amount of Scr3 protein caused by reduction in Scr3 mRNA expression and enhanced secretion of Scr3 protein appears to be important for appropriate adipocyte differentiation. PMID:26677203

  6. Tubby-like protein superfamily member PLSCR3 functions as a negative regulator of adipogenesis in mouse 3T3-L1 preadipocytes by suppressing induction of late differentiation stage transcription factors

    PubMed Central

    Inokawa, Akira; Inuzuka, Tatsutoshi; Takahara, Terunao; Shibata, Hideki; Maki, Masatoshi

    2015-01-01

    PLSCR3 (phospholipid scramblase 3, Scr3) belongs to the superfamily of membrane-associated transcription regulators named Tubby-like proteins (TULPs). Physiological phospholipid scrambling activities of PLSCRs in vivo have been skeptically argued, and knowledge of the biological functions of Scr3 is limited. We investigated the expression of Scr3 during differentiation of mouse 3T3-L1 preadipocytes by Western blotting (WB) and by reverse-transcription and real-time quantitative PCR (RT-qPCR). The Scr3 protein decreased during 3T3-L1 differentiation accompanied by a reduction in the mRNA level, and there was a significant increase in the amount of Scr3 protein secreted into the culture medium in the form of extracellular microvesicles (exosomes). On the other hand, Scr3 expression did not significantly decrease, and the secretion of Scr3 in 3T3 Swiss-albino fibroblasts (a parental cell-line of 3T3-L1) was not increased by differentiation treatment. Overexpression of human Scr3 during 3T3-L1 differentiation suppressed triacylglycerol accumulation and inhibited induction of the mRNAs of late stage pro-adipogenic transcription factors [CCAAT/enhancer-binding protein α (C/EBPα) and peroxisome proliferator-activated receptor γ (PPARγ)] and X-box-binding protein 1 (XBP1). Expression of early stage pro-adipogenic transcription factors (C/EBPβ and C/EBPδ) was not significantly affected. These results suggest that Scr3 functions as a negative regulator of adipogenesis in 3T3-L1 cells at a specific differentiation stage and that decrease in the intracellular amount of Scr3 protein caused by reduction in Scr3 mRNA expression and enhanced secretion of Scr3 protein appears to be important for appropriate adipocyte differentiation. PMID:26677203

  7. A proof-of-principle study of multi-site real-time functional imaging at 3T and 7T: Implementation and validation

    PubMed Central

    Baecke, Sebastian; Lützkendorf, Ralf; Mallow, Johannes; Luchtmann, Michael; Tempelmann, Claus; Stadler, Jörg; Bernarding, Johannes

    2015-01-01

    Real-time functional Magnetic Resonance Imaging (rtfMRI) is used mainly for neurofeedback or for brain-computer interfaces (BCI). But multi-site rtfMRI could in fact help in the application of new interactive paradigms such as the monitoring of mutual information flow or the controlling of objects in shared virtual environments. For that reason, a previously developed framework that provided an integrated control and data analysis of rtfMRI experiments was extended to enable multi-site rtfMRI. Important new components included a data exchange platform for analyzing the data of both MR scanners independently and/or jointly. Information related to brain activation can be displayed separately or in a shared view. However, a signal calibration procedure had to be developed and integrated in order to permit the connecting of sites that had different hardware and to account for different inter-individual brain activation levels. The framework was successfully validated in a proof-of-principle study with twelve volunteers. Thus the overall concept, the calibration of grossly differing signals, and BCI functionality on each site proved to work as required. To model interactions between brains in real-time, more complex rules utilizing mutual activation patterns could easily be implemented to allow for new kinds of social fMRI experiments. PMID:25672521

  8. A proof-of-principle study of multi-site real-time functional imaging at 3T and 7T: Implementation and validation.

    PubMed

    Baecke, Sebastian; Lützkendorf, Ralf; Mallow, Johannes; Luchtmann, Michael; Tempelmann, Claus; Stadler, Jörg; Bernarding, Johannes

    2015-01-01

    Real-time functional Magnetic Resonance Imaging (rtfMRI) is used mainly for neurofeedback or for brain-computer interfaces (BCI). But multi-site rtfMRI could in fact help in the application of new interactive paradigms such as the monitoring of mutual information flow or the controlling of objects in shared virtual environments. For that reason, a previously developed framework that provided an integrated control and data analysis of rtfMRI experiments was extended to enable multi-site rtfMRI. Important new components included a data exchange platform for analyzing the data of both MR scanners independently and/or jointly. Information related to brain activation can be displayed separately or in a shared view. However, a signal calibration procedure had to be developed and integrated in order to permit the connecting of sites that had different hardware and to account for different inter-individual brain activation levels. The framework was successfully validated in a proof-of-principle study with twelve volunteers. Thus the overall concept, the calibration of grossly differing signals, and BCI functionality on each site proved to work as required. To model interactions between brains in real-time, more complex rules utilizing mutual activation patterns could easily be implemented to allow for new kinds of social fMRI experiments. PMID:25672521

  9. Cell-free Embryonic Stem Cell Extract-Mediated Derivation of Multi-potent Stem Cells from NIH3T3 Fibroblasts for Functional and Anatomical Ischemic Tissue Repair

    PubMed Central

    Rajasingh, Johnson; Lambers, Erin; Hamada, Hiromichi; Bord, Evelyn; Thorne, Tina; Goukassian, Ilona; Krishnamurthy, Prasanna; Rosen, Kenneth M.; Ahluwalia, Deepali; Zhu, Yan; Qin, Gangjian; Losordo, Douglas W.; Kishore, Raj

    2008-01-01

    The oocyte-independent source for the generation of pluripotent stem cells is one of the ultimate goals in regenerative medicine. We report that upon exposure to mouse ES cell (ESC) extracts, reversibly permeabilized NIH3T3 cells undergo de-differentiation followed by stimulus-induced re-differentiation into multiple lineage cell types. Genome-wide expression profiling revealed significant differences between NIH3T3 control and ESC extract treated NIH3T3 cells including the re-activation of ESC specific transcripts. Epigenetically, ESC extracts induced CpG de-methylation of Oct4 promoter, hyper-acetylation of histones 3 and 4 and decreased lysine 9 (K-9) dimethylation of histone 3. In mouse models of surgically-induced hind limb ischemia (HLI) or acute myocardial infarction (AMI) transplantation of reprogrammed NIH3T3 cells significantly improved post-injury physiological functions and showed anatomical evidence of engraftment and trans-differentiation into skeletal muscle, endothelial cell and cardiomyocytes. These data provide evidence for the generation of functional multi-potent stem like cells from terminally differentiated somatic cells without the introduction of retroviral mediated trans-genes or ESC fusion. PMID:18483406

  10. Functional Magnetic Resonance Imaging and Pediatric Anxiety

    ERIC Educational Resources Information Center

    Pine, Daniel S.; Guyer, Amanda E.; Leibenluft, Ellen; Peterson, Bradley S.; Gerber, Andrew

    2008-01-01

    The use of functional magnetic resonance imaging in investigating pediatric anxiety disorders is studied. Functional magnetic resonance imaging can be utilized in demonstrating parallels between the neural architecture of difference in anxiety of humans and the neural architecture of attention-orienting behavior in nonhuman primates or rodents.…

  11. 3T MR imaging of the brain.

    PubMed

    DeLano, Mark C; Fisher, Charles

    2006-02-01

    The advent of very high field clinical scanners that operate at 3T is taking structural and functional imaging to new levels and is reinvigorating clinical spectroscopy, fMR imaging, and noncontrast-enhanced methods of MRA. Most of the challenges that are related to 3T imaging have been addressed to facilitate routine clinical imaging. An awareness of the complexities that underlie the solutions to these challenges is important to the continued improvements to the 3T platform so that its maximal potential can be reached. The development of the multichannel-head coils and the improvement in the design of body coils, concurrently with the development of multichannel capabilities that enable parallel imaging, have benefited all field platforms. Perhaps the added value of parallel imaging has been greatest at 3T where the additional signal can be exploited. The definition of very high field is a moving target, and may be well on its way to 7.0 T, although in terms of the current clinical state of the art, 3T is our current reference. PMID:16530636

  12. Magnetic fields and density functional theory

    SciTech Connect

    Salsbury Jr., Freddie

    1999-02-01

    A major focus of this dissertation is the development of functionals for the magnetic susceptibility and the chemical shielding within the context of magnetic field density functional theory (BDFT). These functionals depend on the electron density in the absence of the field, which is unlike any other treatment of these responses. There have been several advances made within this theory. The first of which is the development of local density functionals for chemical shieldings and magnetic susceptibilities. There are the first such functionals ever proposed. These parameters have been studied by constructing functionals for the current density and then using the Biot-Savart equations to obtain the responses. In order to examine the advantages and disadvantages of the local functionals, they were tested numerically on some small molecules.

  13. Functionalized magnetic nanoparticle analyte sensor

    DOEpatents

    Yantasee, Wassana; Warner, Maryin G; Warner, Cynthia L; Addleman, Raymond S; Fryxell, Glen E; Timchalk, Charles; Toloczko, Mychailo B

    2014-03-25

    A method and system for simply and efficiently determining quantities of a preselected material in a particular solution by the placement of at least one superparamagnetic nanoparticle having a specified functionalized organic material connected thereto into a particular sample solution, wherein preselected analytes attach to the functionalized organic groups, these superparamagnetic nanoparticles are then collected at a collection site and analyzed for the presence of a particular analyte.

  14. Tutte polynomial in functional magnetic resonance imaging

    NASA Astrophysics Data System (ADS)

    García-Castillón, Marlly V.

    2015-09-01

    Methods of graph theory are applied to the processing of functional magnetic resonance images. Specifically the Tutte polynomial is used to analyze such kind of images. Functional Magnetic Resonance Imaging provide us connectivity networks in the brain which are represented by graphs and the Tutte polynomial will be applied. The problem of computing the Tutte polynomial for a given graph is #P-hard even for planar graphs. For a practical application the maple packages "GraphTheory" and "SpecialGraphs" will be used. We will consider certain diagram which is depicting functional connectivity, specifically between frontal and posterior areas, in autism during an inferential text comprehension task. The Tutte polynomial for the resulting neural networks will be computed and some numerical invariants for such network will be obtained. Our results show that the Tutte polynomial is a powerful tool to analyze and characterize the networks obtained from functional magnetic resonance imaging.

  15. Extracellular calcium-sensing-receptor (CaR)-mediated opening of an outward K(+) channel in murine MC3T3-E1 osteoblastic cells: evidence for expression of a functional CaR

    NASA Technical Reports Server (NTRS)

    Ye, C. P.; Yamaguchi, T.; Chattopadhyay, N.; Sanders, J. L.; Vassilev, P. M.; Brown, E. M.; O'Malley, B. W. (Principal Investigator)

    2000-01-01

    The existence in osteoblasts of the G-protein-coupled extracellular calcium (Ca(o)(2+))-sensing receptor (CaR) that was originally cloned from parathyroid and kidney remains controversial. In our recent studies, we utilized multiple detection methods to demonstrate the expression of CaR transcripts and protein in several osteoblastic cell lines, including murine MC3T3-E1 cells. Although we and others have shown that high Ca(o)(2+) and other polycationic CaR agonists modulate the function of MC3T3-E1 cells, none of these actions has been unequivocally shown to be mediated by the CaR. Previous investigations using neurons and lens epithelial cells have shown that activation of the CaR stimulates Ca(2+)-activated K(+) channels. Because osteoblastic cells express a similar type of channel, we have examined the effects of specific "calcimimetic" CaR activators on the activity of a Ca(2+)-activated K(+) channel in MC3T3-E1 cells as a way of showing that the CaR is not only expressed in those cells but is functionally active. Patch-clamp analysis in the cell-attached mode showed that raising Ca(o)(2+) from 0.75 to 2.75 mmol/L elicited about a fourfold increase in the open state probability (P(o)) of an outward K(+) channel with a conductance of approximately 92 pS. The selective calcimimetic CaR activator, NPS R-467 (0.5 micromol/L), evoked a similar activation of the channel, while its less active stereoisomer, NPSS-467 (0.5 micromol/L), did not. Thus, the CaR is not only expressed in MC3T3-E1 cells, but is also functionally coupled to the activity of a Ca(2+)-activated K(+) channel. This receptor, therefore, could transduce local or systemic changes in Ca(o)(2+) into changes in the activity of this ion channel and related physiological processes in these and perhaps other osteoblastic cells.

  16. Functional Nanomaterials Useful for Magnetic Refrigeration Systems

    NASA Astrophysics Data System (ADS)

    Aslani, Amir

    Magnetic refrigeration is an emerging energy efficient and environmentally friendly refrigeration technology. The principle of magnetic refrigeration is based on the effect of varying a magnetic field on the temperature change of a magnetocaloric material (refrigerant). By applying a magnetic field, the magnetic moments of a magnetic material tend to align parallel to it, and the thermal energy released in this process heats the material. Reversibly, the magnetic moments become randomly oriented when the magnetic field is removed, and the material cools down. The heating and the cooling of a refrigerant in response to a changing magnetic field is similar to the heating and the cooling of a gaseous medium in response to an adiabatic compression and expansion in a conventional refrigeration system. One requirement to make a practical magnetic refrigerator is to have a large temperature change per unit of applied magnetic field, with sufficiently wide operating temperature. So far, no commercially viable magnetic refrigerator has been built primarily due to the low temperature change of bulk refrigerants, the added burden of hysteresis, and the system's low cooling capacity. The purpose of this dissertation is to explore magnetic refrigeration system. First, the Active Magnetic Regenerator (AMR) system built by Shir et al at the GWU's Institute for Magnetics Research (IMR) is optimized by tuning the heat transfer medium parameters and system's operating conditions. Next, by reviewing literature and works done so far on refrigerants, a number of materials that may be suitable to be used in magnetic refrigeration technology were identified. Theoretical work by Bennett et al showed an enhancement in magnetocaloric effect of magnetic nanoparticles. Research was performed on functional magnetic nanoparticles and their use in magnetic refrigeration technology. Different aspects such as the size, shape, chemical composition, structure and interaction of the nanoparticle with

  17. FUNCTIONAL AND ANATOMICAL DIFFERENCES BETWEEN CONTINENT AND INCONTINENT MEN POST RADICAL PROSTATECTOMY ON URODYNAMICS AND 3T MRI: A PILOT STUDY

    PubMed Central

    Cameron, Anne P.; Suskind, Anne M.; Neer, Charlene; Hussain, Hero; Montgomery, Jeffrey; Latini, Jerilyn M.; DeLancey, John O

    2014-01-01

    Aims There are competing hypotheses about the etiology of post prostatectomy incontinence (PPI).The purpose of this study was to determine the anatomical and functional differences between men with and without PPI. Methods Case control study of continent and incontinent men after radical prostatectomy who underwent functional and anatomic studies with urodynamics and 3.0 Tesla MRI. All men were at least 12 months post prostatectomy and none had a history of pelvic radiation or any prior surgery for incontinence. Results Baseline demographics, surgical approach and pathology were similar between incontinent (cases) (n=14) and continent (controls) (n=12) men. Among the cases, the average 24 hour pad weight was 400.0 ±176.9 grams with a mean of 2.4 ±0.7 pads per day. Urethral pressure profiles at rest did not significantly differ between groups; however with a Kegel maneuver the rise in urethral pressure was 2.6 fold higher in controls. On MRI, the urethral length was 31–35% shorter and the bladder neck was 28.9 degrees more funneled in cases. There were no differences in levator ani muscle size between groups. There was distortion of the sphincter area in 85.7% of cases and in 16.7% of controls (p=0.001). Conclusions Men with PPI were not able to increase urethral pressure with a Kegel maneuver despite similar resting urethral pressure profiles. Additionally, incontinent men had shorter urethras and were more likely to have distortion of the sphincter area. All suggesting that the sphincter in men with PPI is both diminutive and poorly functional. PMID:24752967

  18. Quantitative pharmacokinetic analysis of prostate cancer DCE-MRI at 3T: comparison of two arterial input functions on cancer detection with digitized whole mount histopathological validation.

    PubMed

    Fennessy, Fiona M; Fedorov, Andriy; Penzkofer, Tobias; Kim, Kyung Won; Hirsch, Michelle S; Vangel, Mark G; Masry, Paul; Flood, Trevor A; Chang, Ming-Ching; Tempany, Clare M; Mulkern, Robert V; Gupta, Sandeep N

    2015-09-01

    Accurate pharmacokinetic (PK) modeling of dynamic contrast enhanced MRI (DCE-MRI) in prostate cancer (PCa) requires knowledge of the concentration time course of the contrast agent in the feeding vasculature, the so-called arterial input function (AIF). The purpose of this study was to compare AIF choice in differentiating peripheral zone PCa from non-neoplastic prostatic tissue (NNPT), using PK analysis of high temporal resolution prostate DCE-MRI data and whole-mount pathology (WMP) validation. This prospective study was performed in 30 patients who underwent multiparametric endorectal prostate MRI at 3.0T and WMP validation. PCa foci were annotated on WMP slides and MR images using 3D Slicer. Foci ≥0.5cm(3) were contoured as tumor regions of interest (TROIs) on subtraction DCE (early-arterial - pre-contrast) images. PK analyses of TROI and NNPT data were performed using automatic AIF (aAIF) and model AIF (mAIF) methods. A paired t-test compared mean and 90th percentile (p90) PK parameters obtained with the two AIF approaches. Receiver operating characteristic (ROC) analysis determined diagnostic accuracy (DA) of PK parameters. Logistic regression determined correlation between PK parameters and histopathology. Mean TROI and NNPT PK parameters were higher using aAIF vs. mAIF (p<0.05). There was no significant difference in DA between AIF methods: highest for p90 volume transfer constant (K(trans)) (aAIF differences in the area under the ROC curve (Az) = 0.827; mAIF Az=0.93). Tumor cell density correlated with aAIF K(trans) (p=0.03). Our results indicate that DCE-MRI using both AIF methods is excellent in discriminating PCa from NNPT. If quantitative DCE-MRI is to be used as a biomarker in PCa, the same AIF method should be used consistently throughout the study. PMID:25683515

  19. Magnetic spectroscopy and microscopy of functional materials

    SciTech Connect

    Jenkins, Catherine Ann

    2011-05-01

    Heusler intermetallics Mn2Y Ga and X2MnGa (X; Y =Fe, Co, Ni) undergo tetragonal magnetostructural transitions that can result in half metallicity, magnetic shape memory, or the magnetocaloric effect. Understanding the magnetism and magnetic behavior in functional materials is often the most direct route to being able to optimize current materials for todays applications and to design novel ones for tomorrow. Synchrotron soft x-ray magnetic spectromicroscopy techniques are well suited to explore the the competing effects from the magnetization and the lattice parameters in these materials as they provide detailed element-, valence-, and site-specifc information on the coupling of crystallographic ordering and electronic structure as well as external parameters like temperature and pressure on the bonding and exchange. Fundamental work preparing the model systems of spintronic, multiferroic, and energy-related compositions is presented for context. The methodology of synchrotron spectroscopy is presented and applied to not only magnetic characterization but also of developing a systematic screening method for future examples of materials exhibiting any of the above effects. The chapter progression is as follows: an introduction to the concepts and materials under consideration (Chapter 1); an overview of sample preparation techniques and results, and the kinds of characterization methods employed (Chapter 2); spectro- and microscopic explorations of X2MnGa/Ge (Chapter 3); spectroscopic investigations of the composition series Mn2Y Ga to the logical Mn3Ga endpoint (Chapter 4); and a summary and overview of upcoming work (Chapter 5). Appendices include the results of a Think Tank for the Graduate School of Excellence MAINZ (Appendix A) and details of an imaging project now in progress on magnetic reversal and domain wall observation in the classical Heusler material Co2FeSi (Appendix B).

  20. Simulating functional magnetic materials on supercomputers.

    PubMed

    Gruner, Markus Ernst; Entel, Peter

    2009-07-22

    The recent passing of the petaflop per second landmark by the Roadrunner project at the Los Alamos National Laboratory marks a preliminary peak of an impressive world-wide development in the high-performance scientific computing sector. Also, purely academic state-of-the-art supercomputers such as the IBM Blue Gene/P at Forschungszentrum Jülich allow us nowadays to investigate large systems of the order of 10(3) spin polarized transition metal atoms by means of density functional theory. Three applications will be presented where large-scale ab initio calculations contribute to the understanding of key properties emerging from a close interrelation between structure and magnetism. The first two examples discuss the size dependent evolution of equilibrium structural motifs in elementary iron and binary Fe-Pt and Co-Pt transition metal nanoparticles, which are currently discussed as promising candidates for ultra-high-density magnetic data storage media. However, the preference for multiply twinned morphologies at smaller cluster sizes counteracts the formation of a single-crystalline L1(0) phase, which alone provides the required hard magnetic properties. The third application is concerned with the magnetic shape memory effect in the Ni-Mn-Ga Heusler alloy, which is a technologically relevant candidate for magnetomechanical actuators and sensors. In this material strains of up to 10% can be induced by external magnetic fields due to the field induced shifting of martensitic twin boundaries, requiring an extremely high mobility of the martensitic twin boundaries, but also the selection of the appropriate martensitic structure from the rich phase diagram. PMID:21828528

  1. Functionalized magnetic nanoparticles: A novel heterogeneous catalyst support

    EPA Science Inventory

    Functionalized magnetic nanoparticles have emerged as viable alternatives to conventional materials, as robust, high-surface-area heterogeneous catalyst supports. Post-synthetic surface modification protocol for magnetic nanoparticles has been developed that imparts desirable che...

  2. Functional renormalization group approach to noncollinear magnets

    NASA Astrophysics Data System (ADS)

    Delamotte, B.; Dudka, M.; Mouhanna, D.; Yabunaka, S.

    2016-02-01

    A functional renormalization group approach to d -dimensional, N -component, noncollinear magnets is performed using various truncations of the effective action relevant to study their long distance behavior. With help of these truncations we study the existence of a stable fixed point for dimensions between d =2.8 and d =4 for various values of N focusing on the critical value Nc(d ) that, for a given dimension d , separates a first-order region for N Nc(d ) . Our approach concludes to the absence of a stable fixed point in the physical—N =2 ,3 and d =3 —cases, in agreement with the ɛ =4 -d expansion and in contradiction with previous perturbative approaches performed at fixed dimension and with recent approaches based on the conformal bootstrap program.

  3. Experimental and first-principles characterization of functionalized magnetic nanoparticles.

    PubMed

    Antipas, Georgios S E; Statharas, Eleftherios; Tserotas, Philippos; Papadopoulos, Nikolaos; Hristoforou, E

    2013-06-24

    Magnetic iron oxide nanoparticles synthesized by coprecipitation and thermal decomposition yield largely monodisperse size distributions. The diameters of the coprecipitated particles measured by X-ray diffraction and transmission electron microscopy are between approximately 9 and 15 nm, whereas the diameters of thermally decomposed particles are in the range of 8 to 10 nm. Coprecipitated particles are indexed as magnetite-rich and thermally decomposed particles as maghemite-rich; however, both methods produce a mixture of magnetite and maghemite. Fourier transform IR spectra reveal that the nanoparticles are coated with at least two layers of oleic acid (OA) surfactant. The inner layer is postulated to be chemically adsorbed on the nanoparticle surface whereas the rest of the OA is physically adsorbed, as indicated by carboxyl O-H stretching modes above 3400 cm(-1). Differential thermal analysis (DTA) results indicate a double-stepped weight loss process, the lower-temperature step of which is assigned to condensation due to physically adsorbed or low-energy bonded OA moieties. Density functional calculations of Fe-O clusters, the inverse spinel cell, and isolated OA, as well as OA in bidentate linkage with ferrous and ferric atoms, suggest that the higher-temperature DTA stage could be further broken down into two regions: one in which condensation is due ferrous/ferrous- and/or ferrous/ferric-OA and the other due to condensation from ferrous/ferric- and ferric/ferric-OA complexes. The latter appear to form bonds with the OA carbonyl group of energy up to fivefold that of the bond formed by the ferrous/ferrous pairs. Molecular orbital populations indicate that such increased stability of the ferric/ferric pair is due to the contribution of the low-lying Fe(3+) t(2g) states into four bonding orbitals between -0.623 and -0.410 a.u. PMID:23649714

  4. Functional magnetic resonance imaging of the lung.

    PubMed

    Biederer, J; Heussel, C P; Puderbach, M; Wielpuetz, M O

    2014-02-01

    Beyond being a substitute for X-ray, computed tomography, and scintigraphy, magnetic resonance imaging (MRI) inherently combines morphologic and functional information more than any other technology. Lung perfusion: The most established method is first-pass contrast-enhanced imaging with bolus injection of gadolinium chelates and time-resolved gradient-echo (GRE) sequences covering the whole lung (1 volume/s). Images are evaluated visually or semiquantitatively, while absolute quantification remains challenging due to the nonlinear relation of T1-shortening and contrast material concentration. Noncontrast-enhanced perfusion imaging is still experimental, either based on arterial spin labeling or Fourier decomposition. The latter is used to separate high- and low-frequency oscillations of lung signal related to the effects of pulsatile blood flow. Lung ventilation: Using contrast-enhanced first-pass perfusion, lung ventilation deficits are indirectly identified by hypoxic vasoconstriction. More direct but still experimental approaches use either inhalation of pure oxygen, an aerosolized contrast agent, or hyperpolarized noble gases. Fourier decomposition MRI based on the low-frequency lung signal oscillation allows for visualization of ventilation without any contrast agent. Respiratory mechanics: Time-resolved series with high background signal such as GRE or steady-state free precession visualize the movement of chest wall, diaphragm, mediastinum, lung tissue, tracheal wall, and tumor. The assessment of volume changes allows drawing conclusions on regional ventilation. With this arsenal of functional imaging capabilities at high spatial and temporal resolution but without radiation burden, MRI will find its role in regional functional lung analysis and will therefore overcome the sensitivity of global lung function analysis for repeated short-term treatment monitoring. PMID:24481761

  5. Surface functionalization and characterization of magnetic polystyrene microbeads.

    PubMed

    Yang, Chengli; Guan, Yueping; Xing, Jianmin; Liu, Huizhou

    2008-08-19

    A new approach to the surface functionalization of magnetic polystyrene microbeads with chloroacetyl chloride in the presence of aluminum chloride was reported. Composite microbeads consisting of polymer-coated iron oxide nanoparticles were prepared by spraying suspension polymerization. Functional chloride groups were introduced onto the surface of magnetic polystyrene microbeads by surface chemical reaction without destroying the magnetite nanoparticles within the microbeads. First, a complex was synthesized by a reaction between aluminum chloride and chloroacetyl chloride. Then, the complex was added dropwise to the solution of magnetic polystyrene microbeads, and a surface acylation reaction between complex and polystyrene microbeads was carried out. Subsequently, the amino groups were coupled to the magnetic microbeads via an ammonolysis reaction between ethylenediamine and chloride groups on the acylated magnetic polystyrene microbeads. The chemical composition, surface functional groups, and magnetism of the magnetic polystyrene microbeads before and after surface functionalization were characterized by Fourier transform infrared spectroscopy and vibrating sample magnetometry. The results showed that the surface functionalization reaction had little impact on the magnetism of the microbeads. The content of surface amino groups on the magnetic polystyrene microbeads was found to be 0.2 mmol/g. An affinity dye, Cibacron Blue F3G-A (CB), was then immobilized to prepare a magnetic affinity adsorbent. It was confirmed from X-ray photoelectron spectroscopy spectra that the CB molecules were covalently coupled on the magnetic microbeads. PMID:18624417

  6. Selecting for Function: Solution Synthesis of Magnetic Nanopropellers

    PubMed Central

    2013-01-01

    We show that we can select magnetically steerable nanopropellers from a set of carbon coated aggregates of magnetic nanoparticles using weak homogeneous rotating magnetic fields. The carbon coating can be functionalized, enabling a wide range of applications. Despite their arbitrary shape, all nanostructures propel parallel to the vector of rotation of the magnetic field. We use a simple theoretical model to find experimental conditions to select nanopropellers which are predominantly smaller than previously published ones. PMID:24127909

  7. Synthesis and characterization of functionalized magnetic nanoparticles

    NASA Astrophysics Data System (ADS)

    Biswal, Dipti; Peeples, Brianna N.; Spence, Destiny D.; Peeples, Caryn; Bell, Crystal N.; Pradhan, A. K.

    2012-04-01

    Magnetic nanoparticles have been used in a wide array of industrial and biomedical applications due to their unique properties at the nanoscale level. They are extensively used in magnetic resonance imaging (MRI), magnetic hyperthermia treatment, drug delivery, and in assays for biological separations. Furthermore, superparamagnetic nanoparticles are of large interest for in vivo applications. However, these unmodified nanoparticles aggregate and consequently lose their superparamagnetic behaviors, due to high surface to volume ratio and strong dipole to dipole interaction. For these reasons, surface coating is necessary for the enhancement and effectiveness of magnetic nanoparticles to be used in various applications. In addition to providing increased stability to the nanoparticles in different solvents or media, stabilizers such as surfactants, organic/inorganic molecules, polymer and co-polymers are employed as surface coatings, which yield magnetically responsive systems. In this work we present the synthesis and magnetic characterization of Fe3O4 nanoparticles coated with 3-aminopropyltriethoxy silane (APS) and citric acid. The particles magnetic hysteresis was measured by a superconducting quantum interference device (SQUID) magnetometer with an in-plane magnetic field. The uncoated and coated magnetic nanoparticles were characterized by using fourier transform infrared (FTIR), UV-vis, X-ray diffraction, transmission electron microscopy, and thermo-gravimetric analysis.

  8. Correlation analysis between S3T and SFT/MTK vector magnetograms

    NASA Astrophysics Data System (ADS)

    Liang, H. F.; Sin, S. A.; Ma, L.

    2008-07-01

    Three components of the vector magnetic field, flux density B, inclination γ and azimuth χ of the active region NOAA10507 are derived from the two-dimensional Stokes spectral data obtained by the S3T at the Yunnan Observatory. The distributions of the longitudinal magnetic field and the transverse magnetic field are contoured on the basis of the three components. The distributions indicate that the active region is a very complicated sunspot group which is mainly composed of five sunspots, including one of negative polarity and four positive ones. Comparing the vector magnetograms obtained by S3T and the SFT/MTK, it is found that there is basic agreement on the longitudinal fields of S3T and SFT/MTK magnetograms with a correlation coefficient ρ=0.842, and the two distributions of transverse magnetic field obtained by S3T and SFT/MTK have correlation coefficients, ρ=0.423 and ρ=0.72.

  9. Plasma system of the GOL-3T facility

    SciTech Connect

    Arzhannikov, A. V.; Burdakov, A. V.; Burmasov, V. S.; Ivanov, I. A.; Kuznetsov, S. A.; Kuklin, K. N.; Mekler, K. I.; Polosatkin, S. V.; Postupaev, V. V. Rovenskikh, A. F.; Sinitsky, S. L.; Sklyarov, V. F.

    2015-11-15

    The plasma system and diagnostics of the new facility GOL-3T are described. This facility is the final result of the first stage in the deep upgrade of the GOL-3 multiple-mirror system, which has operated at the Budker Institute of Nuclear Physics since 1988. The upgrade project supposes creation of two new independent facilities at the site of GOL-3. The GOL-3T facility is intended to study the physics of beam—plasma interaction and generation of subterahertz electromagnetic radiation during the collective relaxation of a high-power relativistic electron beam with a duration of 5–10 μs. Studies on the physics of multiple-mirror plasma confinement in axisymmetric magnetic systems will be continued in a new range of experiment parameters at the second facility, named GOL-NB.

  10. Magnetic Resonance, Functional (fMRI) -- Brain

    MedlinePlus

    ... powerful magnetic field, radio frequency pulses and a computer to produce detailed pictures of organs, soft tissues, ... The images can then be examined on a computer monitor, transmitted electronically, printed or copied to a ...

  11. Eight-channel transmit/receive body MRI coil at 3T.

    PubMed

    Vernickel, P; Röschmann, P; Findeklee, C; Lüdeke, K-M; Leussler, Ch; Overweg, J; Katscher, U; Grässlin, I; Schünemann, K

    2007-08-01

    Multichannel transmit magnetic resonance imaging (MR) systems have the potential to compensate for signal-intensity variations occurring at higher field strengths due to wave propagation effects in tissue. Methods such as RF shimming and local excitation in combination with parallel transmission can be applied to compensate for these effects. Moreover, parallel transmission can be applied to ease the excitation of arbitrarily shaped magnetization patterns. The implementation of these methods adds new requirements in terms of MRI hardware. This article describes the design of a decoupled eight-element transmit/receive body coil for 3T. The setup of the coil is explained, starting with standard single-channel resonators. Special focus is placed on the decoupling of the elements to obtain independent RF resonators. After a brief discussion of the underlying theory, the properties and limitations of the coil are outlined. Finally, the functionality and capabilities of the coil are demonstrated using RF measurements as well as MRI sequences. PMID:17654592

  12. An engineered glove for investigating the neural correlates of finger movements using functional magnetic resonance imaging

    PubMed Central

    Bonzano, Laura; Tacchino, Andrea; Roccatagliata, Luca; Inglese, Matilde; Mancardi, Giovanni Luigi; Novellino, Antonio; Bove, Marco

    2015-01-01

    Objective measurement of concomitant finger motor performance is recommended for functional magnetic resonance imaging (fMRI) studies investigating brain activity during finger tapping tasks, because performance modality and ability can influence the selection of different neural networks. In this study, we present a novel glove system for quantitative evaluation of finger opposition movements during fMRI (called Glove Analyzer for fMRI, GAF). Several tests for magnetic resonance (MR) compatibility were performed concerning magnet forces, image artifacts and right functioning of the system. Then, pilot fMRI of finger opposition tasks were conducted at 1.5T and 3T to investigate the neural correlates of sequences of finger opposition movements with the right hand, with simultaneous behavioral recording by means of GAF. All the MR compatibility tests succeeded, and the fMRI analysis revealed mainly the activation of the left sensorimotor areas and right cerebellum, regions that are known to be involved in finger movements. No artifactual clusters were detected in the activation maps. At the same time, through the parameters calculated by GAF it was possible to describe the sensorimotor strategy adopted by the subjects during the required task. Thus, the proposed device resulted to be MR compatible and can be useful for future fMRI studies investigating the neural correlates of finger opposition movements, allowing follow-up studies and comparisons among different groups of patients. PMID:26441600

  13. An engineered glove for investigating the neural correlates of finger movements using functional magnetic resonance imaging.

    PubMed

    Bonzano, Laura; Tacchino, Andrea; Roccatagliata, Luca; Inglese, Matilde; Mancardi, Giovanni Luigi; Novellino, Antonio; Bove, Marco

    2015-01-01

    Objective measurement of concomitant finger motor performance is recommended for functional magnetic resonance imaging (fMRI) studies investigating brain activity during finger tapping tasks, because performance modality and ability can influence the selection of different neural networks. In this study, we present a novel glove system for quantitative evaluation of finger opposition movements during fMRI (called Glove Analyzer for fMRI, GAF). Several tests for magnetic resonance (MR) compatibility were performed concerning magnet forces, image artifacts and right functioning of the system. Then, pilot fMRI of finger opposition tasks were conducted at 1.5T and 3T to investigate the neural correlates of sequences of finger opposition movements with the right hand, with simultaneous behavioral recording by means of GAF. All the MR compatibility tests succeeded, and the fMRI analysis revealed mainly the activation of the left sensorimotor areas and right cerebellum, regions that are known to be involved in finger movements. No artifactual clusters were detected in the activation maps. At the same time, through the parameters calculated by GAF it was possible to describe the sensorimotor strategy adopted by the subjects during the required task. Thus, the proposed device resulted to be MR compatible and can be useful for future fMRI studies investigating the neural correlates of finger opposition movements, allowing follow-up studies and comparisons among different groups of patients. PMID:26441600

  14. Hybride magnetic nanostructure based on amino acids functionalized polypyrrole

    SciTech Connect

    Nan, Alexandrina Bunge, Alexander; Turcu, Rodica

    2015-12-23

    Conducting polypyrrole is especially promising for many commercial applications because of its unique optical, electric, thermal and mechanical properties. We report the synthesis and characterization of novel pyrrole functionalized monomers and core-shell hybrid nanostructures, consisting of a conjugated polymer layer (amino acids functionalized pyrrole copolymers) and a magnetic nanoparticle core. For functionalization of the pyrrole monomer we used several amino acids: tryptophan, leucine, phenylalanine, serine and tyrosine. These amino acids were linked via different types of hydrophobic linkers to the nitrogen atom of the pyrrole monomer. The magnetic core-shell hybrid nanostructures are characterized by various methods such as FTIR spectroscopy, transmission electron microscopy (TEM) and magnetic measurements.

  15. Hybride magnetic nanostructure based on amino acids functionalized polypyrrole

    NASA Astrophysics Data System (ADS)

    Nan, Alexandrina; Bunge, Alexander; Turcu, Rodica

    2015-12-01

    Conducting polypyrrole is especially promising for many commercial applications because of its unique optical, electric, thermal and mechanical properties. We report the synthesis and characterization of novel pyrrole functionalized monomers and core-shell hybrid nanostructures, consisting of a conjugated polymer layer (amino acids functionalized pyrrole copolymers) and a magnetic nanoparticle core. For functionalization of the pyrrole monomer we used several amino acids: tryptophan, leucine, phenylalanine, serine and tyrosine. These amino acids were linked via different types of hydrophobic linkers to the nitrogen atom of the pyrrole monomer. The magnetic core-shell hybrid nanostructures are characterized by various methods such as FTIR spectroscopy, transmission electron microscopy (TEM) and magnetic measurements.

  16. Rationalisation of distribution functions for models of nanoparticle magnetism

    NASA Astrophysics Data System (ADS)

    El-Hilo, M.; Chantrell, R. W.

    2012-08-01

    A formalism is presented which reconciles the use of different distribution functions of particle diameter in analytical models of the magnetic properties of nanoparticle systems. For the lognormal distribution a transformation is derived which shows that a distribution of volume fraction transforms into a lognormal distribution of particle number albeit with a modified median diameter. This transformation resolves an apparent discrepancy reported in Tournus and Tamion [Journal of Magnetism and Magnetic Materials 323 (2011) 1118].

  17. Tumor Volume and Metabolism of Prostate Cancer Determined by Proton Magnetic Resonance Spectroscopic Imaging at 3T Without Endorectal Coil Reveal Potential Clinical Implications in the Context of Radiation Oncology;Prostate cancer; Magnetic resonance spectroscopic imaging; Radiation oncology; Tumor volume; Biomarkers

    SciTech Connect

    Crehange, Gilles; Parfait, Sebastien; Liegard, Melanie; Maingon, Philippe; Ben Salem, Douraied; Cochet, Alexandre; Funes de la Vega, Mathilde; Cormier, Luc; Bonnetain, Franck; Mirjolet, Celine; Brunotte, Francois; Walker, Paul M.

    2011-07-15

    Purpose: To determine whether a relationship exists between the tumor volume (TV) or relative choline content determined using magnetic resonance spectroscopy imaging (MRSI) at 3T and the clinical prognostic parameters for patients with localized prostate cancer (PCa). Methods and Materials: A total of 72 men (mean age, 67.8 {+-} 6.2 years) were stratified as having low-risk (n = 26), intermediate-risk (n = 24), or high-risk (n = 22) PCa. MRSI was performed at 3T using a phased-array coil. Spectra are expressed as the total choline/citrate, total choline plus creatine/citrate, and total choline plus polyamines plus creatine/citrate ratios. The mean ratio of the most pathologic voxels and the MRSI-based TV were also determined. Results: The mean values of the total choline/citrate, total choline plus creatine/citrate, and total choline plus polyamine plus creatine/citrate ratios were greater for Stage T2b or greater tumors vs. Stage T2a or less tumors: 7.53 {+-} 13.60 vs. 2.31 {+-} 5.65 (p = .018), 8.98 {+-} 14.58 vs. 2.56 {+-} 5.70 (p = .016), and 10.32 {+-} 15.47 vs. 3.55 {+-} 6.16 (p = .014), respectively. The mean MRSI-based TV for Stage T2b or greater and Stage T2a or less tumors was significantly different (2.23 {+-} 2.62 cm{sup 3} vs. 1.26 {+-} 2.06 cm{sup 3}, respectively; p = .030). This TV correlated with increased prostate-specific antigen levels (odds ratio, 1.293; p = .012). Patients with high-risk PCa had a larger TV than did the patients with intermediate-risk PCa. A similar result was found for the intermediate-risk group compared with the low-risk group (odds ratio, 1.225; p = .041). Conclusion: Biomarkers expressing the relative choline content and TV were significant parameters for the localization of PCa and could be helpful for determining the prognosis more accurately.

  18. Renal relevant radiology: renal functional magnetic resonance imaging.

    PubMed

    Ebrahimi, Behzad; Textor, Stephen C; Lerman, Lilach O

    2014-02-01

    Because of its noninvasive nature and provision of quantitative measures of a wide variety of physiologic parameters, functional magnetic resonance imaging (MRI) shows great potential for research and clinical applications. Over the past decade, application of functional MRI extended beyond detection of cerebral activity, and techniques for abdominal functional MRI evolved. Assessment of renal perfusion, glomerular filtration, interstitial diffusion, and parenchymal oxygenation turned this modality into an essential research and potentially diagnostic tool. Variations in many renal physiologic markers can be detected using functional MRI before morphologic changes become evident in anatomic magnetic resonance images. Moreover, the framework of functional MRI opened a window of opportunity to develop novel pathophysiologic markers. This article reviews applications of some well validated functional MRI techniques, including perfusion, diffusion-weighted imaging, and blood oxygen level-dependent MRI, as well as some emerging new techniques such as magnetic resonance elastography, which might evolve into clinically useful tools. PMID:24370767

  19. Functionalization of whole‐cell bacterial reporters with magnetic nanoparticles

    PubMed Central

    Zhang, Dayi; Fakhrullin, Rawil F.; Özmen, Mustafa; Wang, Hui; Wang, Jian; Paunov, Vesselin N.; Li, Guanghe; Huang, Wei E.

    2011-01-01

    Summary We developed a biocompatible and highly efficient approach for functionalization of bacterial cell wall with magnetic nanoparticles (MNPs). Three Acinetobacter baylyi ADP1 chromosomally based bioreporters, which were genetically engineered to express bioluminescence in response to salicylate, toluene/xylene and alkanes, were functionalized with 18 ± 3 nm iron oxide MNPs to acquire magnetic function. The efficiency of MNPs functionalization of Acinetobacter bioreporters was 99.96 ± 0.01%. The MNPs‐functionalized bioreporters (MFBs) can be remotely controlled and collected by an external magnetic field. The MFBs were all viable and functional as good as the native cells in terms of sensitivity, specificity and quantitative response. More importantly, we demonstrated that salicylate sensing MFBs can be applied to sediments and garden soils, and semi‐quantitatively detect salicylate in those samples by discriminably recovering MFBs with a permanent magnet. The magnetically functionalized cells are especially useful to complex environments in which the indigenous cells, particles and impurities may interfere with direct measurement of bioreporter cells and conventional filtration is not applicable to distinguish and harvest bioreporters. The approach described here provides a powerful tool to remotely control and selectively manipulate MNPs‐functionalized cells in water and soils. It would have a potential in the application of environmental microbiology, such as bioremediation enhancement and environment monitoring and assessment. PMID:21255376

  20. Arbitrary function generator for APS injector synchrotron correction magnets

    SciTech Connect

    Despe, O.D.

    1990-11-07

    The APS injector synchrotron ring measures about 368 m in circumference. In order to obtain the precision of the magnetic field required for the positron acceleration from 450 Mev to 7.7 Gev with low beam loss, eighty correction magnets are distributed around its circumference. These magnets provide the vernier field changes required for beam orbit correction during the acceleration phase of the injector synchrotron cycle. Because of mechanical imperfections in the construction, as well as installation of real dipole and multi-pole magnets, the exact field correction required at each correction magnet location is not known until a beam is actually accelerated. It is therefore essential that a means is provided to generate a correction field that is a function of the beam energy from injection until extraction for each correction magnet. The fairly large number of correction magnets in the system requires that the arbitrary function generator design be as simple as possible yet provide the required performance. An important, required performance feature is that the function can be changed or modified ``on the fly``, to provide the operator with a real-time feel during the tune up process. The arbitrary function generator described in this report satisfies these requirements.

  1. Design and characterization of combined function multipole magnet for accelerators

    SciTech Connect

    Sinha, Gautam; Singh, Gurnam

    2008-12-15

    This paper presents the design and analysis of a multipurpose combined function magnet for use in accelerators. This magnet consists of three corrector magnets: (i) skew quadrupole, (ii) horizontal dipole, and (iii) vertical dipole magnets, along with the main sextupole magnet. The strength of the corrector magnets is smaller than that of the main sextupole magnet. The strength of all the four magnets can be varied independently. The excitation strength required to produce skew quadrupole gradient and the presence of various multipole components in the magnet are estimated using first order perturbation theory. The experimental data for the variation of the sextupole strength and its higher order multipoles in the presence of skew quadrupole excitations are presented and compared to the theoretical predictions. Simulation using two-dimensional fine element code, Poisson, is also done. Results obtained from all the above three methods are found to be in good agreement with each other. The variations of skew quadrupole gradient for different sextupole excitations are also measured. The validity of this theory is also checked for various combinations of excitations including the case where magnet gets saturated. The excitation strengths required for producing the horizontal and vertical dipole fields are estimated analytically along with the presence of various multipoles. Theoretical predictions of permissible multipoles are compared to the results obtained from simulation.

  2. Magnetic Iron Oxide Nanoparticles: Synthesis and Surface Functionalization Strategies

    NASA Astrophysics Data System (ADS)

    Wu, Wei; He, Quanguo; Jiang, Changzhong

    2008-10-01

    Surface functionalized magnetic iron oxide nanoparticles (NPs) are a kind of novel functional materials, which have been widely used in the biotechnology and catalysis. This review focuses on the recent development and various strategies in preparation, structure, and magnetic properties of naked and surface functionalized iron oxide NPs and their corresponding application briefly. In order to implement the practical application, the particles must have combined properties of high magnetic saturation, stability, biocompatibility, and interactive functions at the surface. Moreover, the surface of iron oxide NPs could be modified by organic materials or inorganic materials, such as polymers, biomolecules, silica, metals, etc. The problems and major challenges, along with the directions for the synthesis and surface functionalization of iron oxide NPs, are considered. Finally, some future trends and prospective in these research areas are also discussed.

  3. Magnetic Iron Oxide Nanoparticles: Synthesis and Surface Functionalization Strategies

    PubMed Central

    2008-01-01

    Surface functionalized magnetic iron oxide nanoparticles (NPs) are a kind of novel functional materials, which have been widely used in the biotechnology and catalysis. This review focuses on the recent development and various strategies in preparation, structure, and magnetic properties of naked and surface functionalized iron oxide NPs and their corresponding application briefly. In order to implement the practical application, the particles must have combined properties of high magnetic saturation, stability, biocompatibility, and interactive functions at the surface. Moreover, the surface of iron oxide NPs could be modified by organic materials or inorganic materials, such as polymers, biomolecules, silica, metals, etc. The problems and major challenges, along with the directions for the synthesis and surface functionalization of iron oxide NPs, are considered. Finally, some future trends and prospective in these research areas are also discussed. PMID:21749733

  4. Dual-source parallel radiofrequency excitation ACR phantom magnetic resonance imaging at 3 T: Assessment of the effect of image quality on high-contrast spatial resolution, percent signal ghosting, and low-contrast object detectability in comparison with conventional single-source transmission

    NASA Astrophysics Data System (ADS)

    Lee, Kyung-Bae; Park, Yong-Sung; Choe, Bo-Young

    2013-10-01

    The purpose of the present study was to assess dual-source parallel radiofrequency (RF) excitation American College of Radiology (ACR) phantom magnetic resonance (MR) imaging at 3T compared with conventional single-source RF transmission and compared with the standard ACR MRI phantom test. We used a 3T MR scanner equipped with dual-source parallel RF excitation and an 8-channel head phased array coil. We employed T1- and T2-weighted fast spin echo (FSE) pulse sequences for an assessment of the impact of image quality on high-contrast spatial resolution, percent signal ghosting and low-contrast object detectability following the ACR MRI quality control (QC) manual. With geometric accuracy and identical slice locations, dual RFs using dual-source parallel RF excitation MR showed an advantage over single RF using dual-source parallel RF excitation MR and conventional MR in terms of high-contrast spatial resolution (p < 0.010), percent signal ghosting (p < 0.010), and low-contrast object detectability (p < 0.010). The quality of the image from the dual-source parallel RF excitation MR equipment was superior to that of the image from conventional MR equipment for the ACR phantom. We need to pursue dual-source parallel RF excitation MR studies involving various clinical cases.

  5. Forensic age estimation via 3-T magnetic resonance imaging of ossification of the proximal tibial and distal femoral epiphyses: Use of a T2-weighted fast spin-echo technique.

    PubMed

    Ekizoglu, Oguzhan; Hocaoglu, Elif; Inci, Ercan; Can, Ismail Ozgur; Aksoy, Sema; Kazimoglu, Cemal

    2016-03-01

    Radiation exposure during forensic age estimation is associated with ethical implications. It is important to prevent repetitive radiation exposure when conducting advanced ultrasonography (USG) and magnetic resonance imaging (MRI). The purpose of this study was to investigate the utility of 3.0-T MRI in determining the degree of ossification of the distal femoral and proximal tibial epiphyses in a group of Turkish population. We retrospectively evaluated coronal T2-weighted and turbo spin-echo sequences taken upon MRI of 503 patients (305 males, 198 females; age 10-30 years) using a five-stage method. Intra- and interobserver variations were very low. (Intraobserver reliability was κ=0.919 for the distal femoral epiphysis and κ=0.961 for the proximal tibial epiphysis, and interobserver reliability was κ=0.836 for the distal femoral epiphysis and κ=0.885 for the proximal tibial epiphysis.) Spearman's rank correlation analysis indicated a significant positive relationship between age and the extent of ossification of the distal femoral and proximal tibial epiphyses (p<0.001). Comparison of male and female data revealed significant between-gender differences in the ages at first attainment of stages 2, 3, and 4 ossifications of the distal femoral epiphysis and stage 1 and 4 ossifications of the proximal tibial epiphysis (p<0.05). The earliest ages at which ossification of stages 3, 4, and 5 was evident in the distal femoral epiphysis were 14, 17, and 22 years in males and 13, 16, and 21 years in females, respectively. Proximal tibial epiphysis of stages 3, 4, and 5 ossification was first noted at ages 14, 17, and 18 years in males and 13, 15, and 16 years in females, respectively. MRI of the distal femoral and proximal tibial epiphyses is an alternative, noninvasive, and reliable technique to estimate age. PMID:26797254

  6. A comparison of distributional considerations with statistical analysis of resting state fMRI at 3T and 7T

    NASA Astrophysics Data System (ADS)

    Yang, Xue; Holmes, Martha J.; Newton, Allen T.; Morgan, Victoria L.; Landman, Bennett A.

    2012-02-01

    Ultra-high field 7T magnetic resonance imaging (MRI) offers potentially unprecedented spatial resolution of functional activity within the human brain through increased signal and contrast to noise ratios over traditional 1.5T and 3T MRI scanners. However, the effects physiological and imaging artifacts are also greatly increased. Traditional statistical parametric mapping theories based on distributional properties representative of data acquired at lower fields may be inadequate for new 7T data. Herein, we investigate the model fitting residuals based on two 7T and one 3T protocols. We find that model residuals are substantively more non-Gaussian at 7T relative to 3T. Imaging slices that passed through regions with peak inhomogeneity problems (e.g., mid-brain acquisitions for the 7T hippocampus) exhibited visually higher degrees of distortion along with spatially correlated and extreme values of kurtosis (a measure of non- Gaussianity). The impacts of artifacts have been previously addressed for 3T data by estimating the covariance matrix of the regression errors. We further extend the robust estimation approach for autoregressive models and evaluate the qualitative impacts of this technique relative to traditional inference. Clear differences in statistical significance are shown between inferences based on classical versus robust assumptions, which suggest that inferences based on Gaussian assumptions are subject to practical (as well as theoretical) concerns regarding their power and validity. Hence, modern statistical approaches, such as the robust autoregressive model posed herein, are appropriate and suitable for inference with ultra-high field functional magnetic resonance imaging.

  7. Functionalization of polydopamine coated magnetic nanoparticles with biological entities

    NASA Astrophysics Data System (ADS)

    Mǎgeruşan, Lidia; Mrówczyński, Radosław; Turcu, Rodica

    2015-12-01

    New hybrid materials, obtained through introduction of cysteine, lysine and folic acid as biological entities into polydopamine-coated magnetite nanoparticles, are reported. The syntheses are straight forward and various methods were applied for structural and morphological characterization of the resulting nanoparticles. XPS proved a very powerful tool for surface chemical analysis and it evidences the functionalization of polydopamine coated magnetite nanoparticles. The superparamagnetic behavior and the high values of saturation magnetization recommend all products for further application where magnetism is important for targeting, separation, or heating by alternative magnetic fields.

  8. Lysophosphatidic acid receptor-5 negatively regulates cellular responses in mouse fibroblast 3T3 cells

    SciTech Connect

    Dong, Yan; Hirane, Miku; Araki, Mutsumi; Fukushima, Nobuyuki; Tsujiuchi, Toshifumi

    2014-04-04

    Highlights: • LPA{sub 5} inhibits the cell growth and motile activities of 3T3 cells. • LPA{sub 5} suppresses the cell motile activities stimulated by hydrogen peroxide in 3T3 cells. • Enhancement of LPA{sub 5} on the cell motile activities inhibited by LPA{sub 1} in 3T3 cells. • The expression and activation of Mmp-9 were inhibited by LPA{sub 5} in 3T3 cells. • LPA signaling via LPA{sub 5} acts as a negative regulator of cellular responses in 3T3 cells. - Abstract: Lysophosphatidic acid (LPA) signaling via G protein-coupled LPA receptors (LPA{sub 1}–LPA{sub 6}) mediates a variety of biological functions, including cell migration. Recently, we have reported that LPA{sub 1} inhibited the cell motile activities of mouse fibroblast 3T3 cells. In the present study, to evaluate a role of LPA{sub 5} in cellular responses, Lpar5 knockdown (3T3-L5) cells were generated from 3T3 cells. In cell proliferation assays, LPA markedly stimulated the cell proliferation activities of 3T3-L5 cells, compared with control cells. In cell motility assays with Cell Culture Inserts, the cell motile activities of 3T3-L5 cells were significantly higher than those of control cells. The activity levels of matrix metalloproteinases (MMPs) were measured by gelatin zymography. 3T3-L5 cells stimulated the activation of Mmp-2, correlating with the expression levels of Mmp-2 gene. Moreover, to assess the co-effects of LPA{sub 1} and LPA{sub 5} on cell motile activities, Lpar5 knockdown (3T3a1-L5) cells were also established from Lpar1 over-expressing (3T3a1) cells. 3T3a1-L5 cells increased the cell motile activities of 3T3a1 cells, while the cell motile activities of 3T3a1 cells were significantly lower than those of control cells. These results suggest that LPA{sub 5} may act as a negative regulator of cellular responses in mouse fibroblast 3T3 cells, similar to the case for LPA{sub 1}.

  9. Cobalt silica magnetic nanoparticles with functional surfaces

    NASA Astrophysics Data System (ADS)

    Vadala, Michael L.; Zalich, Michael A.; Fulks, David B.; St. Pierre, Tim G.; Dailey, James P.; Riffle, Judy S.

    2005-05-01

    Cobalt nanoparticles encased in polysiloxane block copolymers have been heated at 600-700 °C to form protective shells around the particles, which contain crosslinked Si-O structures, and to anneal the cobalt. Methods to functionalize and modify the surfaces of the pyrolyzed/annealed silica-cobalt complexes with amines, isocyanates, poly(ethylene oxide), poly( L-lactide) and polydimethylsiloxane (PDMS) are presented.

  10. SEVEN TOPICS IN FUNCTIONAL MAGNETIC RESONANCE IMAGING

    PubMed Central

    BANDETTINI, PETER A.

    2010-01-01

    Functional MRI (fMRI) is a non-invasive brain imaging methodology that started in 1991 and allows human brain activation to be imaged at high resolution within only a few minutes. Because it has extremely high sensitivity, is relatively easy to implement, and can be performed on most standard clinical MRI scanners. It continues to grow at an explosive rate throughout the world. Over the years, at any given time, fMRI has been defined by only a handful of major topics that have been the focus of researchers using and developing the methodology. In this review, I attempt to take a snapshot of the field of fMRI as it is in mid-2009 by discussing the seven topics that I feel are most on the minds of fMRI researchers. The topics are, in no particular order or grouping: (1) Clinical impact, (2) Utilization of individual functional maps, (3) fMRI signal interpretation, (4) Pattern effect mapping and decoding, (5) Endogenous oscillations, (6) MRI technology, and (7) Alternative functional contrast mechanisms. Most of these topics are highly interdependent, each advancing as the others advance. While most fMRI involves applications towards clinical or neuroscience questions, all applications are fundamentally dependent on advances in basic methodology as well as advances in our understanding of the relationship between neuronal activity and fMRI signal changes. This review neglects almost completely an in-depth discussion of applications. Rather the discussions are on the methods and interpretation. PMID:19938211

  11. Posttraumatic Stress Disorder: Structural Characterization with 3-T MR Imaging.

    PubMed

    Li, Shiguang; Huang, Xiaoqi; Li, Lingjiang; Du, Fei; Li, Jing; Bi, Feng; Lui, Su; Turner, Jessica A; Sweeney, John A; Gong, Qiyong

    2016-08-01

    Purpose To explore cerebral alterations related to the emergence of posttraumatic stress disorder (PTSD) by using three-dimensional T1-weighted imaging and also to explore the relationship of gray and white matter abnormalities and the anatomic changes with clinical severity and duration of time since the trauma. Materials and Methods Informed consent was provided, and the prospective study was approved by the ethics committee of the West China Hospital. Recruited were 67 patients with PTSD and 78 adult survivors without PTSD 7-15 months after a devastating earthquake in western China. All participants underwent magnetic resonance (MR) imaging with a 3-T imager to obtain anatomic images. Cortical thickness and volumes of 14 subcortical gray matter structures and five subregions of the corpus callosum were analyzed with software. Statistical differences between patients with PTSD and healthy survivors were evaluated with a general linear model. Averaged data from the regions with volumetric or cortical thickness differences between groups were extracted in each individual to examine correlations between morphometric measures and clinical profiles. Results Patients with PTSD showed greater cortical thickness in the right superior temporal gyrus, inferior parietal lobule, and left precuneus (P < .05; Monte Carlo null-z simulation corrected) and showed reduced volume in the posterior portion of the corpus callosum (F = 6.167; P = .014) compared with healthy survivors of the earthquake. PTSD severity was positively correlated with cortical thickness in the left precuneus (r = 0.332; P = .008). The volumes of posterior corpus callosum were negatively correlated with PTSD ratings in all survivors (r = -0.210; P = .013) and with cortical thickness of the left precuneus in patients with PTSD (r = -0.302; P = .017). Conclusion Results indicate that patients with PTSD had alterations in both cerebral gray matter and white matter compared with individuals who experienced

  12. 3-T MR-guided brachytherapy for gynecologic malignancies.

    PubMed

    Kapur, Tina; Egger, Jan; Damato, Antonio; Schmidt, Ehud J; Viswanathan, Akila N

    2012-11-01

    Gynecologic malignancies are a leading cause of death in women worldwide. Standard treatment for many primary and recurrent gynecologic cancer cases includes external-beam radiation followed by brachytherapy. Magnetic resonance (MR) imaging is beneficial in diagnostic evaluation, in mapping the tumor location to tailor radiation dose and in monitoring the tumor response to treatment. Initial studies of MR guidance in gynecologic brachytherapy demonstrate the ability to optimize tumor coverage and reduce radiation dose to normal tissues, resulting in improved outcomes for patients. In this article, we describe a methodology to aid applicator placement and treatment planning for 3 Tesla (3-T) MR-guided brachytherapy that was developed specifically for gynecologic cancers. This methodology has been used in 18 cases from September 2011 to May 2012 in the Advanced Multimodality Image Guided Operating (AMIGO) suite at Brigham and Women's Hospital. AMIGO comprises state-of-the-art tools for MR imaging, image analysis and treatment planning. An MR sequence using three-dimensional (3D)-balanced steady-state free precession in a 3-T MR scanner was identified as the best sequence for catheter identification with ballooning artifact at the tip. 3D treatment planning was performed using MR images. Items in development include software designed to support virtual needle trajectory planning that uses probabilistic bias correction, graph-based segmentation and image registration algorithms. The results demonstrate that 3-T MR image guidance has a role in gynecologic brachytherapy. These novel developments have the potential to improve targeted treatment to the tumor while sparing the normal tissues. PMID:22898699

  13. Optimization of the bio-functionalized area of magnetic biosensors

    NASA Astrophysics Data System (ADS)

    Albisetti, Edoardo; Petti, Daniela; Damin, Francesco; Cretich, Marina; Bagnati, Marta; Sola, Laura; Chiari, Marcella; Bertacco, Riccardo

    2013-06-01

    In this work, calculations and preliminary experimental data for determining the optimal condition for the selective bio-functionalization of magnetic tunneling junction (MTJ)-based biosensors are presented. Results on the detection of biomolecular recognition events employing MTJ-based sensor and magnetic beads are presented and interpreted through calculations, taking into account the dependence of the signal on the distribution of the beads with respect to the sensor. Furthermore, it is demonstrated by calculations that a significant increase in the sensor sensitivity and quantification capability can be achieved by selectively bio-functionalizing an area which corresponds to the sensor active area.

  14. A generalized flux function for three-dimensional magnetic reconnection

    SciTech Connect

    Yeates, A. R.; Hornig, G.

    2011-10-15

    The definition and measurement of magnetic reconnection in three-dimensional magnetic fields with multiple reconnection sites is a challenging problem, particularly in fields lacking null points. We propose a generalization of the familiar two-dimensional concept of a magnetic flux function to the case of a three-dimensional field connecting two planar boundaries. In this initial analysis, we require the normal magnetic field to have the same distribution on both boundaries. Using hyperbolic fixed points of the field line mapping, and their global stable and unstable manifolds, we define a unique flux partition of the magnetic field. This partition is more complicated than the corresponding (well-known) construction in a two-dimensional field, owing to the possibility of heteroclinic points and chaotic magnetic regions. Nevertheless, we show how the partition reconnection rate is readily measured with the generalized flux function. We relate our partition reconnection rate to the common definition of three-dimensional reconnection in terms of integrated parallel electric field. An analytical example demonstrates the theory and shows how the flux partition responds to an isolated reconnection event.

  15. Principles of functional magnetic resonance imaging: application to auditory neuroscience.

    PubMed

    Cacace, A T; Tasciyan, T; Cousins, J P

    2000-05-01

    Functional imaging based on magnetic resonance methods is a new research frontier for exploring a wide range of central nervous system (CNS) functions, including information processing in sensory, motor, cognitive, and linguistic systems. Being able to localize and study human brain function in vivo, in relatively high resolution and in a noninvasive manner, makes this a technique of unparalleled importance. In order to appreciate and fully understand this area of investigation, a tutorial covering basic aspects of this methodology is presented. We introduce functional magnetic resonance imaging (fMRI) by providing an overview of the studies of different sensory systems in response to modality-specific stimuli, followed by an outline of other areas that have potential clinical relevance to the medical, cognitive, and communicative sciences. The discussion then focuses on the basic principles of magnetic resonance methods including magnetic resonance imaging, MR spectroscopy, fMRI, and the potential role that MR technology may play in understanding a wide range of auditory functions within the CNS, including tinnitus-related activity. Because the content of the material found herein might be unfamiliar to some, we provide a broad range of background and review articles to serve as a technical resource. PMID:10821504

  16. PAMAM Dendrimer/pDNA Functionalized-Magnetic Iron Oxide Nanoparticles for Gene Delivery.

    PubMed

    Xiao, Shili; Castro, Rita; Rodrigues, João; Shi, Xiangyang; Tomás, Helena

    2015-08-01

    Herein, we report an easy and ingenious method to functionalize magnetic iron oxide nanoparticles (MNPs) with plasmid DNA (pDNA) to obtain nanohybrid systems suitable for nucleic acid therapy. The nanohybrids were prepared by combining complexes of dendrimers and pDNA (dendriplexes) and poly(styrene) sulfonate-coated MNPs through electrostatic interactions. The effects of the dendrimer generation (generations 2, 4 and 6) and the amine to phosphate group (N/P) ratio on the hydrodynamic diameter, zeta potential, cell viability, cellular internalization and transfection efficiency of the nanohybrids were systematically investigated at different transfection conditions (including incubation time, pDNA concentration, presence or absence of an external magnetic field, and presence or absence of fetal bovine serum). The results confirmed that the nanohybrids were able to transfect NIH 3T3 cells, and that the level of gene expression (the luciferase protein reporter gene was used) was strongly dependent on the dendrimer generation, the N/P ratio, and the pDNA concentration. The best system was based on dendriplex-coated MNPs formed by generation 6 dendrimers at an N/P ratio of 10 that, at optimized conditions, led to a gene expression level which was not significantly different from that obtained only using dendriplexes. In summary, a coherent set of results was reached indicating the potential of the developed nanohybrids as effective gene delivery nanomaterials. PMID:26295139

  17. Surface functionalized biocompatible magnetic nanospheres for cancer hyperthermia.

    SciTech Connect

    Liu, X.; Novosad, V.; Rozhkova, E. A.; Chen, H.; Yefremenko, V.; Pearson, J.; Torno, M.; Bader, S. D.; Rosengart, A. J.; Univ. Chicago Pritzker School of Medicine

    2007-06-01

    We report a simplified single emulsion (oil-in-water) solvent evaporation protocol to synthesize surface functionalized biocompatible magnetic nanospheres by using highly concentrated hydrophobic magnetite (gel) and a mixture of poly(D,L lactide-co-glycolide) (PLGA) and poly(lactic acid-block-polyethylene glycol-maleimide) (PLA-PEG-maleimide) (10:1 by mass) polymers. The as-synthesized particles are approximately spherical with an average diameter of 360-370 nm with polydispersity index of 0.12-0.18, are surface-functionalized with maleimide groups, and have saturation magnetization values of 25-40 emu/g. The efficiency of the heating induced by 400-kHz oscillating magnetic fields is compared for two samples with different magnetite loadings. Results show that these nanospheres have the potential to provide an efficient cancer-targeted hyperthermia.

  18. Peptide-functionalized magnetic nanoparticles for cancer therapy applications

    NASA Astrophysics Data System (ADS)

    Hauser, Anastasia Kruse

    Lung cancer is one of the leading causes of cancer deaths in the United States. Radiation and chemotherapy are conventional treatments, but they result in serious side effects and the probability of tumor recurrence remains high. Therefore, there is an increasing need to enhance the efficacy of conventional treatments. Magnetic nanoparticles have been previously studied for a variety of applications such as magnetic resonance imaging contrast agents, anemia treatment, magnetic cell sorting and magnetically mediated hyperthermia (MMH). In this work, dextran coated iron oxide nanoparticles were developed and functionalized with peptides to target the nanoparticles to either the extracellular matrix (ECM) of tumor tissue or to localize the nanoparticles in subcellular regions after cell uptake. The magnetic nanoparticles were utilized for a variety of applications. First, heating properties of the nanoparticles were utilized to administer hyperthermia treatments combined with chemotherapy. The nanoparticles were functionalized with peptides to target fibrinogen in the ECM and extensively characterized for their physicochemical properties, and MMH combined with chemotherapy was able to enhance the toxicity of chemotherapy. The second application of the nanoparticles was magnetically mediated energy delivery. This treatment does not result in a bulk temperature rise upon actuation of the nanoparticles by an alternating magnetic field (AMF) but rather results in intracellular damage via friction from Brownian rotation or nanoscale heating effects from Neel relaxations. The nanoparticles were functionalized with a cell penetrating peptide to facilitate cell uptake and lysosomal escape. The intracellular effects of the internalized nanoparticles alone and with activation by an AMF were evaluated. Iron concentrations in vivo are highly regulated as excess iron can catalyze the formation of the hydroxyl radical through Fenton chemistry. Although often a concern of using iron

  19. Functional Connectivity Magnetic Resonance Imaging Classification of Autism

    ERIC Educational Resources Information Center

    Anderson, Jeffrey S.; Nielsen, Jared A.; Froehlich, Alyson L.; DuBray, Molly B.; Druzgal, T. Jason; Cariello, Annahir N.; Cooperrider, Jason R.; Zielinski, Brandon A.; Ravichandran, Caitlin; Fletcher, P. Thomas; Alexander, Andrew L.; Bigler, Erin D.; Lange, Nicholas; Lainhart, Janet E.

    2011-01-01

    Group differences in resting state functional magnetic resonance imaging connectivity between individuals with autism and typically developing controls have been widely replicated for a small number of discrete brain regions, yet the whole-brain distribution of connectivity abnormalities in autism is not well characterized. It is also unclear…

  20. A thermal distribution function for relativistic magnetically insulated electron flows

    SciTech Connect

    Desjarlais, M.P.; Sudan, R.N.

    1986-05-01

    A distribution function is presented that may be used to study the effects of finite temperature on the equilibrium and stability properties of magnetically insulated electron flows. This distribution function has the useful property that it generates the thoroughly studied class of constant Q = ..omega../sup 2//sub p//..cap omega../sup 2/ equilibria in its zero-temperature limit. Analytic solutions are given for the general, constant Q, zero-temperature equilibria.

  1. Human brain somatic representation: a functional magnetic resonance mapping

    NASA Astrophysics Data System (ADS)

    Romero-Romo, Juan; Rojas, Rafael; Salgado, Perla; Sánchez-Cortázar, Julián; Vazquez-Vela, Arturo; Barrios, Fernando A.

    2001-10-01

    Central nervous system studies of injury and plasticity for the reorganization in the phantom limb sensation area presented. In particular functional magnetic resonance imaging (fMRI) mapping of the somatic and motor cortex of amputee patients, in the case of referred sensations. Using fMRI we can show the correlation between structure and functional field and study the reorganization due to plasticity in the brain.

  2. In vivo CEST Imaging of Creatine (CrCEST) in Skeletal Muscle at 3T

    PubMed Central

    Kogan, Feliks; Haris, Mohammad; Debrosse, Catherine; Singh, Anup; Nanga, Ravi P.; Cai, Kejia; Hariharan, Hari; Reddy, Ravinder

    2013-01-01

    Purpose To characterize the chemical exchange saturation transfer (CEST) based technique to measure free creatine (Cr), a key component of muscle energy metabolism, distribution in skeletal muscle with high spatial resolution before and after exercise at 3T. Methods CrCEST saturation parameters were empirically optimized for 3T. CEST, T2, magnetization transfer ratio (MTR) and 31P magnetic resonance spectroscopy (MRS) acquisitions of the lower leg were performed before and after mild plantar flexion exercise on a 3T whole-body MR scanner on 6 healthy volunteers. Results The feasibility of imaging Cr changes in skeletal muscle following plantar flexion exercise using CrCEST was demonstrated at 3T. This technique exhibited good spatial resolution and was able to differentiate differences in muscle utilization among subjects. CrCEST results were compared with 31P MRS results showing good agreement in the Cr and PCr recovery kinetics. A relationship of 0.45 % CrCESTasym/mM Cr was observed across all subjects. Conclusion Demonstrated the CrCEST technique could be applied at 3T to measure dynamic changes in creatine in in vivo muscle. The widespread availability and clinical applicability of 3T scanners has the potential to clinically advance this method. PMID:24925857

  3. Deriving a functional form of anhysteretic magnetization function for Jiles-Atherton theory of hysteresis

    NASA Astrophysics Data System (ADS)

    Jiles, David; Raghunathan, Arun; Melikhov, Yevgen; Snyder, John

    2010-03-01

    The Jiles-Atherton (JA) theory explains the ferromagnetic hysteresis through contributions of irreversible and reversible magnetization components [1]. Anhysteretic magnetization function, a function of energy of the moments in a domain, forms a basic building block of this model. This function has known forms for specific cases of anisotropy: axially anisotropic (one-dimensional), planar anisotropic (two-dimensional), and isotropic (three-dimensional) [1, 2]. Hence there is a need to generalize anhysteretic magnetization function to extend JA theory to other forms of anisotropy. In this work, a functional form of anhysteretic magnetization function has been derived. It was shown that this functional form of anhysteretic magnetization with necessary boundary conditions can be reduced to the familiar specific model equations in the particular cases. This work extends the applicability of the JA model to systems with various anisotropy dependences. This research was supported by the UK EPSRC (EP/D057094) and the US NSF (DMR-0402716). [1] D. C. Jiles et. al., JMMM. 61, 48 (1986). [2] Y. M. Shi et. al., JMMM. 187, 75 (1998).

  4. Functional magnetic resonance imaging in medicine and physiology

    SciTech Connect

    Moonen, C.T.W.; van Zijl, P.C.M.; Frank, J.A.; Bihan, D.L.; Becker, E.D. )

    1990-10-05

    Magnetic resonance imaging (MRI) is a well-established diagnostic tool that provides detailed information about macroscopic structure and anatomy. Recent advances in MRI allow the noninvasive spatial evaluation of various biophysical and biochemical processes in living systems. Specifically, the motion of water can be measured in processes such as vascular flow, capillary flow, diffusion, and exchange. In addition, the concentrations of various metabolites can be determined for the assessment of regional regulation of metabolism. Examples are given that demonstrate the use of functional MRI for clinical and research purposes. This development adds a new dimension to the application of magnetic resonance to medicine and physiology.

  5. Turbulent magnetic energy spectrum and the cancellation function of solar photospheric magnetic fields

    NASA Astrophysics Data System (ADS)

    Marschalkó, G.; Petrovay, K.; Petrovay, K.

    2013-11-01

    A simple analytical relation of form α=2κ-1 between the magnetic energy spectral exponent α of the turbulent magnetic field in the solar photosphere and its magnetic flux cancellation exponent κ, valid under certain restrictive assumptions, is tested and extended outside its range of validity in a series of Monte Carlo simulations. In these numerical tests artificial ``magnetograms'' are constructed in 1D and 2D by superposing a discrete set of Fourier modes of the magnetic field distribution with amplitudes following a power law spectrum and measuring the cancellation function on these simulated magnetograms. Our results confirm the validity of the analytical relation and extend it to the domain α<-1 where κ-> 0 as α-> -∞. The observationally derived upper limit of 0.38 on κ implies α<-0.24 in the granular size range, apparently at odds with a small scale dynamo driven in the inertial range.

  6. Advances in Langmuir probe diagnostics of the plasma potential and electron-energy distribution function in magnetized plasma

    NASA Astrophysics Data System (ADS)

    Popov, Tsv K.; Dimitrova, M.; Ivanova, P.; Kovačič, J.; Gyergyek, T.; Dejarnac, R.; Stöckel, J.; Pedrosa, M. A.; López-Bruna, D.; Hidalgo, C.

    2016-06-01

    Advanced Langmuir probe techniques for evaluating the plasma potential and electron-energy distribution function (EEDF) in magnetized plasma are reviewed. It is shown that when the magnetic field applied is very weak and the electrons reach the probe without collisions in the probe sheath the second-derivative Druyvesteyn formula can be used for EEDF evaluation. At low values of the magnetic field, an extended second-derivative Druyvesteyn formula yields reliable results, while at higher values of the magnetic field, the first-derivative probe technique is applicable for precise evaluation of the plasma potential and the EEDF. There is an interval of intermediate values of the magnetic field when both techniques—the extended second-derivative and the first-derivative one—can be used. Experimental results from probe measurements in different ranges of magnetic field are reviewed and discussed: low-pressure argon gas discharges in the presence of a magnetic field in the range from 0.01 to 0.08 T, probe measurements in circular hydrogen plasmas for high-temperature fusion (magnetic fields from 0.45 T to 1.3 T) in small ISTTOK and CASTOR tokamaks, D-shape COMPASS tokamak plasmas, as well as in the TJ-II stellarator. In the vicinity of the last closed flux surface (LCFS) in tokamaks and in the TJ-II stellarator, the EEDF obtained is found to be bi-Maxwellian, while close to the tokamak chamber wall it is Maxwellian. The mechanism of the appearance of a bi-Maxwellian EEDF in the vicinity of the LCFS is discussed. Comparison of the results from probe measurements with those obtained from calculations using the ASTRA and EIRENE codes shows that the main reason for the appearance of a bi-Maxwellian EEDF in the vicinity of the LCFS is the ionization of the neutral atoms.

  7. Anatomical, functional and molecular biomarker applications of magnetic resonance neuroimaging

    PubMed Central

    Liu, Christina H

    2015-01-01

    MRI and magnetic resonance spectroscopy (MRS) along with computed tomography and PET are the most common imaging modalities used in the clinics to detect structural abnormalities and pathological conditions in the brain. MRI generates superb image resolution/contrast without radiation exposure that is associated with computed tomography and PET; MRS and spectroscopic imaging technologies allow us to measure changes in brain biochemistry. Increasingly, neurobiologists and MRI scientists are collaborating to solve neuroscience problems across sub-cellular through anatomical levels. To achieve successful cross-disciplinary collaborations, neurobiologists must have sufficient knowledge of magnetic resonance principles and applications in order to effectively communicate with their MRI colleagues. This review provides an overview of magnetic resonance techniques and how they can be used to gain insight into the active brain at the anatomical, functional and molecular levels with the goal of encouraging neurobiologists to include MRI/MRS as a research tool in their endeavors. PMID:25774094

  8. Isolation of Highly Suppressive CD25+FoxP3+ T Regulatory Cells from G-CSF-Mobilized Donors with Retention of Cytotoxic Anti-Viral CTLs: Application for Multi-Functional Immunotherapy Post Stem Cell Transplantation

    PubMed Central

    Samuel, Edward R.; Beloki, Lorea; Newton, Katy; Mackinnon, Stephen; Lowdell, Mark W.

    2014-01-01

    Previous studies have demonstrated the effective control of cytomegalovirus (CMV) infections post haematopoietic stem cell transplant through the adoptive transfer of donor derived CMV-specific T cells (CMV-T). Strategies for manufacturing CMV immunotherapies has involved a second leukapheresis or blood draw from the donor, which in the unrelated donor setting is not always possible. We have investigated the feasibility of using an aliquot of the original G-CSF-mobilized graft as a starting material for manufacture of CMV-T and examined the activation marker CD25 as a targeted approach for identification and isolation following CMVpp65 peptide stimulation. CD25+ cells isolated from G-CSF-mobilized apheresis revealed a significant increase in the proportion of FoxP3 expression when compared with conventional non-mobilized CD25+ cells and showed a superior suppressive capacity in a T cell proliferation assay, demonstrating the emergence of a population of Tregs not present in non-mobilized apheresis collections. The expansion of CD25+ CMV-T in short-term culture resulted in a mixed population of CD4+ and CD8+ T cells with CMV-specificity that secreted cytotoxic effector molecules and lysed CMVpp65 peptide-loaded phytohaemagglutinin-stimulated blasts. Furthermore CD25 expanded cells retained their suppressive capacity but did not maintain FoxP3 expression or secrete IL-10. In summary our data indicates that CD25 enrichment post CMV stimulation in G-CSF-mobilized PBMCs results in the simultaneous generation of both a functional population of anti-viral T cells and Tregs thus illustrating a potential single therapeutic strategy for the treatment of both GvHD and CMV reactivation following allogeneic haematopoietic stem cell transplantation. The use of G-CSF-mobilized cells as a starting material for cell therapy manufacture represents a feasible approach to alleviating the many problems incurred with successive donations and procurement of cells from unrelated donors

  9. Exponentially localized Wannier functions in periodic zero flux magnetic fields

    NASA Astrophysics Data System (ADS)

    De Nittis, G.; Lein, M.

    2011-11-01

    In this work, we investigate conditions which ensure the existence of an exponentially localized Wannier basis for a given periodic hamiltonian. We extend previous results [Panati, G., Ann. Henri Poincare 8, 995-1011 (2007), 10.1007/s00023-007-0326-8] to include periodic zero flux magnetic fields which is the setting also investigated by Kuchment [J. Phys. A: Math. Theor. 42, 025203 (2009), 10.1088/1751-8113/42/2/025203]. The new notion of magnetic symmetry plays a crucial rôle; to a large class of symmetries for a non-magnetic system, one can associate "magnetic" symmetries of the related magnetic system. Observing that the existence of an exponentially localized Wannier basis is equivalent to the triviality of the so-called Bloch bundle, a rank m hermitian vector bundle over the Brillouin zone, we prove that magnetic time-reversal symmetry is sufficient to ensure the triviality of the Bloch bundle in spatial dimension d = 1, 2, 3. For d = 4, an exponentially localized Wannier basis exists provided that the trace per unit volume of a suitable function of the Fermi projection vanishes. For d > 4 and d ⩽ 2m (stable rank regime) only the exponential localization of a subset of Wannier functions is shown; this improves part of the analysis of Kuchment [J. Phys. A: Math. Theor. 42, 025203 (2009), 10.1088/1751-8113/42/2/025203]. Finally, for d > 4 and d > 2m (unstable rank regime) we show that the mere analysis of Chern classes does not suffice in order to prove triviality and thus exponential localization.

  10. Green's function of compressible Petschek-type magnetic reconnection

    NASA Astrophysics Data System (ADS)

    Penz, Thomas; Semenov, V. S.; Ivanova, V. V.; Heyn, M. F.; Ivanov, I. B.; Biernat, H. K.

    2006-05-01

    We present a method to analyze the wave and shock structures arising from Petschek-type magnetic reconnection. Based on a time-dependent analytical approach developed by Heyn and Semenov [Phys. Plasmas 3, 2725 (1996)] and Semenov et al. [Phys. Plasmas 11, 62 (2004)], we calculate the perturbations caused by a delta function-shaped reconnection electric field, which allows us to achieve a representation of the plasma variables in the form of Green's functions. Different configurations for the initial conditions are considered. In the case of symmetric, antiparallel magnetic fields and symmetric plasma density, the well-known structure of an Alfvén discontinuity, a fast body wave, a slow shock, a slow wave, and a tube wave occurs. In the case of asymmetric, antiparallel magnetic fields, additionally surface waves are found. We also discuss the case of symmetric, antiparallel magnetic fields and asymmetric densities, which leads to a faster propagation in the lower half plane, causing side waves forming a Mach cone in the upper half plane. Complex effects like anisotropic propagation characteristics, intrinsic wave coupling, and the generation of different nonlinear and linear wave modes in a finite β plasma are retained. The temporal evolution of these wave and shock structures is shown.

  11. Characterization of hyaluronate binding proteins isolated from 3T3 and murine sarcoma virus transformed 3T3 cells

    SciTech Connect

    Turley, E.A.; Moore, D.; Hayden, L.J.

    1987-06-02

    A hyaluronic acid binding fraction was purified from the supernatant media of both 3T3 and murine sarcoma virus (MSV) transformed 3T3 cultures by hyaluronate and immunoaffinity chromatography. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis resolved the hyaluronate affinity-purified fraction into three major protein bands of estimated molecular weight (M/sub r,e/) 70K, 66K, and 56K which contained hyaluronate binding activity and which were termed hyaluronate binding proteins (HABP). Hyaluronate affinity chromatography combined with immunoaffinity chromatography, using antibody directed against the larger HABP, allowed a 20-fold purification of HABP. Fractions isolated from 3T3 supernatant medium also contained additional binding molecules in the molecular weight range of 20K. This material was present in vanishingly small amounts and was not detected with a silver stain or with (/sup 35/S)methionine label. The three protein species isolated by hyaluronate affinity chromatography (M/sub r,e/ 70K, 66K, and 56K) were related to one another since they shared antigenic determinants and exhibited similar pI values. In isocratic conditions, HABP occurred as aggregates of up to 580 kilodaltons. Their glycoprotein nature was indicated by their incorporation of /sup 3/H-sugars. Enzyme-linked immunoadsorbent assay showed they were antigenically distinct from other hyaluronate binding proteins such as fibronectin, cartilage link protein, and the hyaluronate binding region of chondroitin sulfate proteoglycan. The results are discussed with regard both to the functional significance of hyaluronate-cell surface interactions in transformed as well as normal cells and to the relationship of HABP to other reported hyaluronate binding proteins.

  12. Magnetic anisotropy of metal functionalized phthalocyanine 2D networks

    NASA Astrophysics Data System (ADS)

    Zhu, Guojun; Zhang, Yun; Xiao, Huaping; Cao, Juexian

    2016-06-01

    The magnetic anisotropy of metal including Cr, Mn, Fe, Co, Mo, Tc, Ru, Rh, W, Re, Os, Ir atoms functionalized phthalocyanine networks have been investigated with first-principles calculations. The magnetic moments can be expressed as 8-n μB with n the electronic number of outmost d shell in the transition metals. The huge magnetocrystalline anisotropy energy (MAE) is obtained by torque method. Especially, the MAE of Re functionalized phthalocyanine network is about 20 meV with an easy axis perpendicular to the plane of phthalocyanine network. The MAE is further manipulated by applying the external biaxial strain. It is found that the MAE is linear increasing with the external strain in the range of -2% to 2%. Our results indicate an effective approach to modulate the MAE for practical application.

  13. Toward functional magnetic stimulation (FMS) theory and experiment.

    PubMed

    Davey, K; Luo, L; Ross, D A

    1994-11-01

    This paper examines the use of magnetic fields to functionally stimulate peripheral nerves. All electric fields are induced via a changing magnetic field whose flux is entirely confined within a closed magnetic circuit. Induced electric fields are simulated using a nonlinear boundary element solver. The induced fields are solved using duality theory. The accuracy of these predictions is verified by saline bath experiments. Next, the theory is applied to the stimulation of nerves using small, partially occluded ferrite and laminated vanadium permendur cores. Experiments demonstrate the successful stimulation of peripheral nerves in the African bullfrog with 11 mA, 153 mV excitations. These results offer a new vista of possibilities in the area of functional nerve stimulation. Unlike functional electric stimulation (FES), FMS does not involve any half cell reactions, and thus would not have the commensurate FES restrictions regarding balanced biphasic stimulation, strength duration balances, and oxidation issues, always exercising care that the electrodes remain in the reversible operating regime. PMID:8001991

  14. Lanthanide-Functionalized Hydrophilic Magnetic Hybrid Nanoparticles: Assembly, Magnetic Behaviour, and Photophysical Properties

    NASA Astrophysics Data System (ADS)

    Han, Shuai; Tang, Yu; Guo, Haijun; Qin, Shenjun; Wu, Jiang

    2016-05-01

    The lanthanide-functionalized multifunctional hybrid nanoparticles combining the superparamagnetic core and the luminescent europium complex were successfully designed and assembled via layer-by-layer strategy in this work. It is noted that the hybrid nanoparticles were modified by a hydrophilic polymer polyethyleneimine (PEI) through hydrogen bonding which bestowed excellent hydrophilicity and biocompatibility on this material. A bright-red luminescence was observed by fluorescence microscopy, revealing that these magnetic-luminescent nanoparticles were both colloidally and chemically stable in PBS solution. Therefore, the nanocomposite with magnetic resonance response and fluorescence probe property is considered to be of great potential in multi-modal bioimaging and diagnostic applications.

  15. Lanthanide-Functionalized Hydrophilic Magnetic Hybrid Nanoparticles: Assembly, Magnetic Behaviour, and Photophysical Properties.

    PubMed

    Han, Shuai; Tang, Yu; Guo, Haijun; Qin, Shenjun; Wu, Jiang

    2016-12-01

    The lanthanide-functionalized multifunctional hybrid nanoparticles combining the superparamagnetic core and the luminescent europium complex were successfully designed and assembled via layer-by-layer strategy in this work. It is noted that the hybrid nanoparticles were modified by a hydrophilic polymer polyethyleneimine (PEI) through hydrogen bonding which bestowed excellent hydrophilicity and biocompatibility on this material. A bright-red luminescence was observed by fluorescence microscopy, revealing that these magnetic-luminescent nanoparticles were both colloidally and chemically stable in PBS solution. Therefore, the nanocomposite with magnetic resonance response and fluorescence probe property is considered to be of great potential in multi-modal bioimaging and diagnostic applications. PMID:27245169

  16. Intraoperative monitoring of motor function by magnetic motor evoked potentials.

    PubMed

    Lee, W Y; Hou, W Y; Yang, L H; Lin, S M

    1995-03-01

    Under etomidate anesthesia, motor evoked potentials produced by magnetic stimulation were successfully recorded from 10 thenar muscles and 10 anterior tibial muscles of eight patients who had undergone surgery on the medulla oblongata and the cervical and thoracic spinal cords. Recordings taken before placing the neural tissue at risk were assessed for variability in amplitude and latency. The lower limit in amplitude was approximately one-third (25-43%) of the baseline. The latencies were more difficult to monitor than were the amplitudes. The latency variations were 2.56 +/- 0.50 milliseconds for the hand and 6.84 +/- 1.37 milliseconds for the leg. During surgery, the unilateral recordings of two patients were transiently lost but partially recovered after a pause in the operation. No obvious postoperative weaknesses in the corresponding limbs occurred. One patient, who showed a permanent loss of unilateral recording, had transient monoplegia with a complete recovery. None of the remaining five patients who had amplitudes larger than one-third of the baseline at the end of the operation had additional motor deficits. Our conclusions are that under etomidate anesthesia, the magnetic motor evoked potentials can be convenient and reliable monitors of motor function, that changes in the amplitude may be superior to those in the latency for intraoperative warning, that the criterion for potential neural damage under magnetic motor evoked potential monitoring might be an amplitude reduction of two-thirds of the control value, and that the magnetic stimulation seems to be more sensitive than the electrical stimulation in the monitoring of motor function and also allows more time and opportunities for the motor function to recover. PMID:7753349

  17. Magnetic Alignment and Charge Transport Improvement in Functional Soft Materials

    NASA Astrophysics Data System (ADS)

    Majewski, Pawel W.

    The realization of nanostructured functional materials by self-assembly in polymers and polymer nanocomposites is adversely affected by persisting structural defects which greatly diminish the performance of the material. The use of magnetic fields to impose long-range order is investigated in three distinct systems - ion-conducting block copolymers, semiconducting nanowire-polymer composites and lyotropic surfactant mesophases. The alignment process is quantitatively studied with X-ray scattering and microscopic methods. Time and temperature resolved data collected in situ during the magnetic experiments provide an insight into the thermodynamic and kinetic aspects of the process. These data together with simultaneous electrical conductivity measurements allow relating fundamental structural properties (e.g., morphology and long-range order) to transport properties (i.e., conductivity). In particular, it is demonstrated that magnetic fields offer a viable route for improvement of electric conductivity in these systems. More than an order of magnitude increase in conductivity is recorded in magnetically-annealed materials. The resulting aligned nanostructured systems are attractive for ordered solid polymer electrolyte membranes, heterojunction photovoltaic devices and generally help to understand charge transport mechanisms in anisotropic heterogeneous systems.

  18. Elucidating the Function of Penetratin and a Static Magnetic Field in Cellular Uptake of Magnetic Nanoparticles

    PubMed Central

    Chaudhary, Suman; Smith, Carol Anne; del Pino, Pablo; de la Fuente, Jesus M.; Mullin, Margaret; Hursthouse, Andrew; Stirling, David; Berry, Catherine C.

    2013-01-01

    Nanotechnology plays an increasingly important role in the biomedical arena. In particular, magnetic nanoparticles (mNPs) have become important tools in molecular diagnostics, in vivo imaging and improved treatment of disease, with the ultimate aim of producing a more theranostic approach. Due to their small sizes, the nanoparticles can cross most of the biological barriers such as the blood vessels and the blood brain barrier, thus providing ubiquitous access to most tissues. In all biomedical applications maximum nanoparticle uptake into cells is required. Two promising methods employed to this end include functionalization of mNPs with cell-penetrating peptides to promote efficient translocation of cargo into the cell and the use of external magnetic fields for enhanced delivery. This study aimed to compare the effect of both penetratin and a static magnetic field with regards to the cellular uptake of 200 nm magnetic NPs and determine the route of uptake by both methods. Results demonstrated that both techniques increased particle uptake, with penetratin proving more cell specific. Clathrin- medicated endocytosis appeared to be responsible for uptake as shown via PCR and western blot, with Pitstop 2 (known to selectively block clathrin formation) blocking particle uptake. Interestingly, it was further shown that a magnetic field was able to reverse or overcome the blocking, suggesting an alternative route of uptake. PMID:24275948

  19. Perpendicular magnetization reversal mechanism of functional FePt films for magnetic storage medium

    NASA Astrophysics Data System (ADS)

    Wei, Da-Hua; Chi, Po-Wei; Chao, Chung-Hua

    2014-11-01

    Magnetization reversal mechanism and related surface morphology of functional FePt(001) alloy films with large perpendicular magnetic anisotropy have been explored by alternate-atomic-layer deposition onto Pt/MgO(100) substrates via electron beam evaporation, and all evaporated films have been kept at in-situ substrate heating temperature of 400 °C. The FePt alloy film was composed of ultrathin [Fe (0.5 nm)/Pt (0.5 nm)]n Fe/Pt multilayer structures. The corresponding thickness of multilayer films was controlled by the periodic bilayer numbers (n) and varied in the range from 15 nm (n = 15) to 30 nm (n = 30). The surface topography was observed and varied from granular-like island to continuous microstructures with increasing the periodic numbers of Fe/Pt bilayer films. The measurement of angular dependent coercivity showed a tendency of the near rotation of reverse-domain type (n = 15) shift towards the domain-wall motion as a typical peak behavior (n = 30) with increasing the periodic bilayer numbers of Fe/Pt multilayers. On the basis of all magnetic measurements and corresponding magnetization analysis, indicating that the perpendicular magnetization reversal mechanism and related surface morphology of ordered FePt(001) alloy films could be systematically controlled by varying the periodic bilayer numbers accompanied with the thickness dependence.

  20. Nuclear chiral and magnetic rotation in covariant density functional theory

    NASA Astrophysics Data System (ADS)

    Meng, Jie; Zhao, Pengwei

    2016-05-01

    Excitations of chiral rotation observed in triaxial nuclei and magnetic and/or antimagnetic rotations (AMR) seen in near-spherical nuclei have attracted a lot of attention. Unlike conventional rotation in well-deformed or superdeformed nuclei, here the rotational axis is not necessary coinciding with any principal axis of the nuclear density distribution. Thus, tilted axis cranking (TAC) is mandatory to describe these excitations self-consistently in the framework of covariant density functional theory (CDFT). We will briefly introduce the formalism of TAC–CDFT and its application for magnetic and AMR phenomena. Configuration-fixed CDFT and its predictions for nuclear chiral configurations and for favorable triaxial deformation parameters are also presented, and the discoveries of the multiple chiral doublets in 133Ce and 103Rh are discussed.

  1. Mechanisms and prevention of thermal injury from gamma radiosurgery headframes during 3T MR imaging.

    PubMed

    Bennett, Marcus C; Wiant, David B; Gersh, Jacob A; Dolesh, Wendy; Ding, X; Best, Ryan C M; Bourland, J D

    2012-01-01

    Magnetic resonance imaging (MRI) is regularly used for stereotactic imaging of Gamma Knife (GK) radiosurgery patients for GK treatment planning. MRI-induced thermal injuries have occurred and been reported for GK patients with attached metallic headframes. Depending on the specific MR imaging and headframe conditions, a skin injury from MRI-induced heating can potentially occur where the four headframe screws contact the skin surface of the patient's head. Higher MR field strength has a greater heating potential. Two primary heating mechanisms, electromagnetic induction and the antenna effect, are possible. In this study, MRI-induced heating from a 3T clinical MRI scanner was investigated for stereotactic headframes used in gamma radiosurgery and neurosurgery. Using melons as head phantoms, optical thermometers were used to characterize the temperature profile at various points of the melon headframe composite as a function of two 3T MR pulse sequence protocols. Different combinations of GK radiosurgery headframe post and screw designs were tested to determine best and worst combinations for MRI-induced heating. Temperature increases were measured for all pulse sequences tested, indicating that the potential exists for MRI-induced skin heating and burns at the headframe attachment site. This heating originates with electromagnetic induction caused by the RF fields inducing current in a loop formed by the headframe, mounting screws, and the region of the patient's head located between any of the two screws. This induced current is then resistively dissipated, with the regions of highest resistance, located at the headframe screw-patient head interface, experiencing the most heating. Significant heating can be prevented by replacing the metallic threads holding the screw with electrically insulated nuts, which is the heating prevention and patient safety recommendation of the GK manufacturer. Our results confirm that the manufacturer's recommendation to use

  2. Linear constraint minimum variance beamformer functional magnetic resonance inverse imaging

    PubMed Central

    Lin, Fa-Hsuan; Witzel, Thomas; Zeffiro, Thomas A.; Belliveau, John W.

    2011-01-01

    Accurate estimation of the timing of neural activity is required to fully model the information flow among functionally specialized regions whose joint activity underlies perception, cognition and action. Attempts to detect the fine temporal structure of task-related activity would benefit from functional imaging methods allowing higher sampling rates. Spatial filtering techniques have been used in magnetoencephalography source imaging applications. In this work, we use the linear constraint minimal variance (LCMV) beamformer localization method to reconstruct single-shot volumetric functional magnetic resonance imaging (fMRI) data using signals acquired simultaneously from all channels of a high density radio-frequency (RF) coil array. The LCMV beamformer method generalizes the existing volumetric magnetic resonance inverse imaging (InI) technique, achieving higher detection sensitivity while maintaining whole-brain spatial coverage and 100 ms temporal resolution. In this paper, we begin by introducing the LCMV reconstruction formulation and then quantitatively assess its performance using both simulated and empirical data. To demonstrate the sensitivity and inter-subject reliability of volumetric LCMV InI, we employ an event-related design to probe the spatial and temporal properties of task-related hemodynamic signal modulations in primary visual cortex. Compared to minimum-norm estimate (MNE) reconstructions, LCMV offers better localization accuracy and superior detection sensitivity. Robust results from both single subject and group analyses demonstrate the excellent sensitivity and specificity of volumetric InI in detecting the spatial and temporal structure of task-related brain activity. PMID:18672071

  3. The 3T3-L1 adipocyte glycogen proteome

    PubMed Central

    2013-01-01

    Background Glycogen is a branched polysaccharide of glucose residues, consisting of α-1-4 glycosidic linkages with α-1-6 branches that together form multi-layered particles ranging in size from 30 nm to 300 nm. Glycogen spatial conformation and intracellular organization are highly regulated processes. Glycogen particles interact with their metabolizing enzymes and are associated with a variety of proteins that intervene in its biology, controlling its structure, particle size and sub-cellular distribution. The function of glycogen in adipose tissue is not well understood but appears to have a pivotal role as a regulatory mechanism informing the cells on substrate availability for triacylglycerol synthesis. To provide new molecular insights into the role of adipocyte glycogen we analyzed the glycogen-associated proteome from differentiated 3T3-L1-adipocytes. Results Glycogen particles from 3T3-L1-adipocytes were purified using a series of centrifugation steps followed by specific elution of glycogen bound proteins using α-1,4 glucose oligosaccharides, or maltodextrins, and tandem mass spectrometry. We identified regulatory proteins, 14-3-3 proteins, RACK1 and protein phosphatase 1 glycogen targeting subunit 3D. Evidence was also obtained for a regulated subcellular distribution of the glycogen particle: metabolic and mitochondrial proteins were abundant. Unlike the recently analyzed hepatic glycogen proteome, no endoplasmic proteins were detected, along with the recently described starch-binding domain protein 1. Other regulatory proteins which have previously been described as glycogen-associated proteins were not detected, including laforin, the AMPK beta-subunit and protein targeting to glycogen (PTG). Conclusions These data provide new molecular insights into the regulation of glycogen-bound proteins that are associated with the maintenance, organization and localization of the adipocyte glycogen particle. PMID:23521774

  4. Functional renormalization group - a new approach to frustrated quantum magnetism

    NASA Astrophysics Data System (ADS)

    Reuther, Johannes

    The experimental and theoretical investigation of quantum spin systems has become one of the central disciplines of contemporary condensed matter physics. From an experimental viewpoint, the field has been significantly fueled by the recent synthesis of novel strongly correlated materials with exotic magnetic or quantum paramagnetic ground states. From a theoretical perspective, however, the numerical treatment of realistic models for quantum magnetism in two and three spatial dimensions still constitutes a serious challenge. This particularly applies to frustrated systems, which complicate the employment of established methods. This talk intends to propagate the pseudofermion functional renormalization group (PFFRG) as a novel approach to determine large size ground state correlations of a wide class of spin Hamiltonians. Using a diagrammatic pseudofermion representation for quantum spin models, the PFFRG performs systematic summations in all two-particle fermionic interaction channels, capturing the correct balance between classical magnetic ordering and quantum fluctuations. Numerical results for various frustrated spin models on different 2D and 3D lattices are reviewed, and benchmarked against other methods if available.

  5. Density Functional Theory applied to magnetic materials: Mn3O4 at different hybrid functionals

    NASA Astrophysics Data System (ADS)

    Ribeiro, R. A. P.; de Lazaro, S. R.; Pianaro, S. A.

    2015-10-01

    Antiferromagnetic Mn3O4 in spinel structure was investigated employing the Density Functional Theory at different hybrid functionals with default HF exchange percentage. Structural, electronic and magnetic properties were examined. Structural results were in agreement with experimental and Hartree-Fock results showing that the octahedral site was distorted by the Jahn-Teller effect, which changed the electron density distribution. Band-gap results for B3LYP and B3PW hybrid functionals were closer to the experimental when compared to PBE0. Mulliken Population Analysis revealed magnetic moments very close to ideal d4 and d5 electron configurations of Mn3+ and Mn2+, respectively. Electron density maps are useful to determine that oxygen atoms mediate the electron transfer between octahedral and tetrahedral clusters. Magnetic properties were investigated from theoretical results for exchange coupling constants. Intratetrahedral and tetra-octahedral interactions were observed to be antiferromagnetic, whereas, octahedral sites presented antiferromagnetic interactions in the same layer and ferromagnetic in adjacent layers. Results showed that only default B3LYP was successful to describe magnetic properties of antiferromagnetic materials in agreement with experimental results.

  6. Functional imaging of the human placenta with magnetic resonance.

    PubMed

    Siauve, Nathalie; Chalouhi, Gihad E; Deloison, Benjamin; Alison, Marianne; Clement, Olivier; Ville, Yves; Salomon, Laurent J

    2015-10-01

    Abnormal placentation is responsible for most failures in pregnancy; however, an understanding of placental functions remains largely concealed from noninvasive, in vivo investigations. Magnetic resonance imaging (MRI) is safe in pregnancy for magnetic fields of up to 3 Tesla and is being used increasingly to improve the accuracy of prenatal imaging. Functional MRI (fMRI) of the placenta has not yet been validated in a clinical setting, and most data are derived from animal studies. FMRI could be used to further explore placental functions that are related to vascularization, oxygenation, and metabolism in human pregnancies by the use of various enhancement processes. Dynamic contrast-enhanced MRI is best able to quantify placental perfusion, permeability, and blood volume fractions. However, the transplacental passage of Gadolinium-based contrast agents represents a significant safety concern for this procedure in humans. There are alternative contrast agents that may be safer in pregnancy or that do not cross the placenta. Arterial spin labeling MRI relies on magnetically labeled water to quantify the blood flows within the placenta. A disadvantage of this technique is a poorer signal-to-noise ratio. Based on arterial spin labeling, placental perfusion in normal pregnancy is 176 ± 91 mL × min(-1) × 100 g(-1) and decreases in cases with intrauterine growth restriction. Blood oxygen level-dependent and oxygen-enhanced MRIs do not assess perfusion but measure the response of the placenta to changes in oxygen levels with the use of hemoglobin as an endogenous contrast agent. Diffusion-weighted imaging and intravoxel incoherent motion MRI do not require exogenous contrast agents, instead they use the movement of water molecules within tissues. The apparent diffusion coefficient and perfusion fraction are significantly lower in placentas of growth-restricted fetuses when compared with normal pregnancies. Magnetic resonance spectroscopy has the ability to extract

  7. Approach to combined-function magnets via symplectic slicing

    NASA Astrophysics Data System (ADS)

    Titze, M.

    2016-05-01

    In this article we describe how to obtain symplectic "slice" maps for combined-function magnets, by using a method of generating functions. A feature of this method is that one can use an unexpanded and unsplit Hamiltonian. From such a slice map we obtain a first-order map which is symplectic at the closed orbit. We also obtain a symplectic kick map. Both results were implemented into the widely used program MAD-X to regain, in particular, the twiss parameters for the sliced model of the Proton Synchrotron at CERN. In addition, we obtain recursion equations for symplectic maps of general time-dependent Hamiltonians, which might be useful even beyond the scope of accelerator physics.

  8. [Functional magnetic resonance imaging in psychiatry and psychotherapy].

    PubMed

    Derntl, B; Habel, U; Schneider, F

    2010-01-01

    technical improvements, functional magnetic resonance imaging (fMRI) has become the most popular and versatile imaging method in psychiatric research. The scope of this manuscript is to briefly introduce the basics of MR physics, the blood oxygenation level-dependent (BOLD) contrast as well as the principles of MR study design and functional data analysis. The presentation of exemplary studies on emotion recognition and empathy in schizophrenia patients will highlight the importance of MR methods in psychiatry. Finally, we will demonstrate insights into new developments that will further boost MR techniques in clinical research and will help to gain more insight into dysfunctional neural networks underlying cognitive and emotional deficits in psychiatric patients. Moreover, some techniques such as neurofeedback seem promising for evaluation of therapy effects on a behavioral and neural level. PMID:20057981

  9. Functional Magnetic Resonance Imaging in Acute Kidney Injury: Present Status

    PubMed Central

    Zhou, Hai Ying; Chen, Tian Wu; Zhang, Xiao Ming

    2016-01-01

    Acute kidney injury (AKI) is a common complication of hospitalization that is characterized by a sudden loss of renal excretory function and associated with the subsequent development of chronic kidney disease, poor prognosis, and increased mortality. Although the pathophysiology of renal functional impairment in the setting of AKI remains poorly understood, previous studies have identified changes in renal hemodynamics, perfusion, and oxygenation as key factors in the development and progression of AKI. The early assessment of these changes remains a challenge. Many established approaches are not applicable to humans because of their invasiveness. Functional renal magnetic resonance (MR) imaging offers an alternative assessment tool that could be used to evaluate renal morphology and function noninvasively and simultaneously. Thus, the purpose of this review is to illustrate the principle, application, and role of the techniques of functional renal MR imaging, including blood oxygen level-dependent imaging, arterial spin labeling, and diffusion-weighted MR imaging, in the management of AKI. The use of gadolinium in MR imaging may exacerbate renal impairment and cause nephrogenic systemic fibrosis. Therefore, dynamic contrast-enhanced MR imaging will not be discussed in this paper. PMID:26925411

  10. Functional Magnetic Resonance Imaging in Acute Kidney Injury: Present Status.

    PubMed

    Zhou, Hai Ying; Chen, Tian Wu; Zhang, Xiao Ming

    2016-01-01

    Acute kidney injury (AKI) is a common complication of hospitalization that is characterized by a sudden loss of renal excretory function and associated with the subsequent development of chronic kidney disease, poor prognosis, and increased mortality. Although the pathophysiology of renal functional impairment in the setting of AKI remains poorly understood, previous studies have identified changes in renal hemodynamics, perfusion, and oxygenation as key factors in the development and progression of AKI. The early assessment of these changes remains a challenge. Many established approaches are not applicable to humans because of their invasiveness. Functional renal magnetic resonance (MR) imaging offers an alternative assessment tool that could be used to evaluate renal morphology and function noninvasively and simultaneously. Thus, the purpose of this review is to illustrate the principle, application, and role of the techniques of functional renal MR imaging, including blood oxygen level-dependent imaging, arterial spin labeling, and diffusion-weighted MR imaging, in the management of AKI. The use of gadolinium in MR imaging may exacerbate renal impairment and cause nephrogenic systemic fibrosis. Therefore, dynamic contrast-enhanced MR imaging will not be discussed in this paper. PMID:26925411

  11. Repeatability and sensitivity of T2* measurements in patients with head and neck squamous cell carcinoma at 3T

    PubMed Central

    Panek, Rafal; Welsh, Liam; Dunlop, Alex; Wong, Kee H.; Riddell, Angela M.; Koh, Dow‐Mu; Schmidt, Maria A.; Doran, Simon; Mcquaid, Dualta; Hopkinson, Georgina; Richardson, Cheryl; Nutting, Christopher M.; Bhide, Shreerang A.; Harrington, Kevin J.; Robinson, Simon P.; Newbold, Kate L.

    2016-01-01

    Purpose To determine whether quantitation of T2* is sufficiently repeatable and sensitive to detect clinically relevant oxygenation levels in head and neck squamous cell carcinoma (HNSCC) at 3T. Materials and Methods Ten patients with newly diagnosed locally advanced HNSCC underwent two magnetic resonance imaging (MRI) scans between 24 and 168 hours apart prior to chemoradiotherapy treatment. A multiple gradient echo sequence was used to calculate T2* maps. A quadratic function was used to model the blood transverse relaxation rate as a function of blood oxygenation. A set of published coefficients measured at 3T were incorporated to account for tissue hematocrit levels and used to plot the dependence of fractional blood oxygenation (Y) on T2* values, together with the corresponding repeatability range. Repeatability of T2* using Bland–Altman analysis, and calculation of limits of agreement (LoA), was used to assess the sensitivity, defined as the minimum difference in fractional blood oxygenation that can be confidently detected. Results T2* LoA for 22 outlined tumor volumes were 13%. The T2* dependence of fractional blood oxygenation increases monotonically, resulting in increasing sensitivity of the method with increasing blood oxygenation. For fractional blood oxygenation values above 0.11, changes in T2* were sufficient to detect differences in blood oxygenation greater than 10% (Δ T2* > LoA for ΔY > 0.1). Conclusion Quantitation of T2* at 3T can detect clinically relevant changes in tumor oxygenation within a wide range of blood volumes and oxygen tensions, including levels reported in HNSCC. J. Magn. Reson. Imaging 2016;44:72–80. PMID:26800280

  12. Evaluation of ventricular function with gated cardiac magnetic resonance imaging.

    PubMed

    Osbakken, M; Yuschok, T

    1986-01-01

    To determine the feasibility of using planar images obtained with gated cardiac magnetic resonance imaging (MRI) techniques to evaluate ventricular contractile function, cardiac chamber volume (V), and ejection fraction (EF) were calculated using MR images obtained in five previously catheterized patients. Patients were imaged with a .15-Tesla 55-cm bore magnet using the ECG to gate the images. Spin echo pulse sequences (30/500, TE/TR) were used to produce images in the transverse (T), coronal (C), and sagittal (S) planes at end diastole (ED) and end systole (ES). Slice thickness was 1.5 cm, with 2-mm resolution. A calibration grid was imaged in each plane to determine correction factors. Cardiac chamber areas were determined via planimetry. An area-length-volume algorithm was used to obtain EDV and ESV. Three combinations of biplane images in ES and ED were used (T/C, T/S, C/S). Volume data were used to calculate EF. Contrast ventriculogram volumes tended to be greater than MRI volumes, but EFs were similar with both techniques. In conclusion, gated cardiac MR images can be used to evaluate the ventricular function parameters of volume and ejection fraction. PMID:3731263

  13. Hyperpolarized Xenon-129 Magnetic Resonance Imaging of Functional Lung Microstructure

    NASA Astrophysics Data System (ADS)

    Dregely, Isabel

    Hyperpolarized 129Xe (HXe) is a non-invasive contrast agent for lung magnetic resonance imaging (MRI), which upon inhalation follows the functional pathway of oxygen in the lung by dissolving into lung tissue structures and entering the blood stream. HXe MRI therefore provides unique opportunities for functional lung imaging of gas exchange which occurs from alveolar air spaces across the air-blood boundary into parenchymal tissue. However challenges in acquisition speed and signal-to-noise ratio have limited the development of a HXe imaging biomarker to diagnose lung disease. This thesis addresses these challenges by introducing parallel imaging to HXe MRI. Parallel imaging requires dedicated hardware. This work describes design, implementation, and characterization of a 32-channel phased-array chest receive coil with an integrated asymmetric birdcage transmit coil tuned to the HXe resonance on a 3 Tesla MRI system. Using the newly developed human chest coil, a functional HXe imaging method, multiple exchange time xenon magnetization transfer contrast (MXTC) is implemented. MXTC dynamically encodes HXe gas exchange into the image contrast. This permits two parameters to be derived regionally which are related to gas-exchange functionality by characterizing tissue-to-alveolar-volume ratio and alveolar wall thickness in the lung parenchyma. Initial results in healthy subjects demonstrate the sensitivity of MXTC by quantifying the subtle changes in lung microstructure in response to orientation and lung inflation. Our results in subjects with lung disease show that the MXTC-derived functional tissue density parameter exhibits excellent agreement with established imaging techniques. The newly developed dynamic parameter, which characterizes the alveolar wall, was elevated in subjects with lung disease, most likely indicating parenchymal inflammation. In light of these observations we believe that MXTC has potential as a biomarker for the regional quantification of 1

  14. A novel RF resonator for human-body MRI at 3 T

    NASA Astrophysics Data System (ADS)

    Son, Hyeok-Woo; Cho, Young-Ki; Yoo, Hyoungsuk

    2014-03-01

    A square-slot-loaded (SSL) radio-frequency (RF) resonator using a microstrip transmission line (MTL) is designed for human-body magnetic resonance imaging (MRI) at 3 T MRI. The SSL RF resonator shows improved RF magnetic fields resulting in more homogenous fields near the center of the phantom than traditional RF resonators using MTL. A multichannel body coil using the SSL RF resonators is also simulated and provides improved parallel excitation performance. In addition, RF shimming for homogenization can be effectively controlled by adjusting the inputs to the eight resonators. Numerical results are obtained by using a spherical phantom and a realistic human-body model at 3 T to calculate the B {1/+} fields.

  15. Unusual Function of Modified Polyolefins for Manipulating Magnetic Nanostructures

    NASA Astrophysics Data System (ADS)

    He, Qingliang; Yuan, Tingting; Wei, Suying; Guo, Zhanhu

    2014-04-01

    The unusual function of a long known plastic additive in industry, polypropylene- graft-maleic anhydride (PP- g-MA), is reviewed for serving as a polymeric surfactant to synthesize and stabilize magnetic nanoparticles (NPs) with tunable morphology and crystalline structure. The synthesis route employs a solution-based, one-pot, bottom-up method. Specifically, magnetic NPs were synthesized through thermo-decomposing organo-metallic precursors [i.e., Fe(CO)5 or Co2(CO)8] in the presence of PP- g-MA in solvent xylene. By simply changing the backbone length/concentration of PP- g-MA, different morphologies (monodispersed hollow vs. chain-like solid, or chain-like vs. monodispersed polyhedral-shaped NPs) and crystalline structures [α- vs. γ-phase for Fe2O3 NPs, or face-centered cubic (fcc)- vs. ɛ-phase for Co NPs] can be controlled simultaneously. In addition, for the chain-like Fe2O3 NPs, a different chain diameter and building block morphology can be controlled by only varying the molecular weight of PP- g-MA.

  16. Monitoring fractional anisotropy in developing rabbit brain using MR diffusion tensor imaging at 3T

    NASA Astrophysics Data System (ADS)

    Jao, Jo-Chi; Yang, Yu-Ting; Hsiao, Chia-Chi; Chen, Po-Chou

    2016-03-01

    The aim of this study was to investigate the factional anisotropy (FA) in various regions of developing rabbit brain using magnetic resonance diffusion tensor imaging (MR DTI) at 3 T. A whole-body clinical MR imaging (MRI) scanner with a 15-channel high resolution knee coil was used. An echo-planar-imaging (EPI)-DTI pulse sequence was performed. Five 5 week-old New Zealand white (NZW) rabbits underwent MRI once per week for 24 weeks. After scanning, FA maps were obtained. ROIs (regions of interests) in the frontal lobe, parietal & temporal lobe, and occipital lobe were measured. FA changes with time were evaluated with a linear regression analysis. The results show that the FA values in all lobes of the brain increased linearly with age. The ranking of FA values was FA(frontal lobe) < FA(parietal & temporal lobe) > FA(occipital lobe). There was significant difference (p < 0.05) among these lobes. FA values are associated with the nerve development and brain functions. The FA change rate could be a biomarker to monitor the brain development. Understanding the FA values of various lobes during development could provide helpful information to diagnosis the abnormal syndrome earlier and have a better treatment and prognosis. This study established a brain MR-DTI protocol for rabbits to investigate the brain anatomy during development using clinical MRI. This technique can be further applied to the pre-clinical diagnosis, treatment, prognosis and follow-up of brain lesions.

  17. Using High Spatial Resolution to Improve BOLD fMRI Detection at 3T

    PubMed Central

    Claise, Béatrice; Jean, Betty

    2015-01-01

    For different functional magnetic resonance imaging experiments using blood oxygenation level-dependent (BOLD) contrast, the acquisition of T2*-weighted scans at a high spatial resolution may be advantageous in terms of time-course signal-to-noise ratio and of BOLD sensitivity when the regions are prone to susceptibility artifacts. In this study, we explore this solution by examining how spatial resolution influences activations elicited when appetizing food pictures are viewed. Twenty subjects were imaged at 3 T with two different voxel volumes, 3.4 μl and 27 μl. Despite the diminution of brain coverage, we found that high-resolution acquisition led to a better detection of activations. Though known to suffer to different degrees from susceptibility artifacts, the activations detected by high spatial resolution were notably consistent with those reported in published activation likelihood estimation meta-analyses, corresponding to taste-responsive regions. Furthermore, these regions were found activated bilaterally, in contrast with previous findings. Both the reduction of partial volume effect, which improves BOLD contrast, and the mitigation of susceptibility artifact, which boosts the signal to noise ratio in certain regions, explained the better detection noted with high resolution. The present study provides further evidences that high spatial resolution is a valuable solution for human BOLD fMRI, especially for studying food-related stimuli. PMID:26550990

  18. Development of a Clinical Functional Magnetic Resonance Imaging Service

    PubMed Central

    Rigolo, Laura; Stern, Emily; Deaver, Pamela; Golby, Alexandra J.; Mukundan, Srinivasan

    2013-01-01

    One of the limitations of anatomical based imaging approaches is its relative inability to identify whether specific brain functions may be compromised by the location of brain lesions or contemplated brain surgeries. For this reason, methods for identifying the regions of eloquent brain that should not be disturbed are absolutely critical to the surgeon. By accurately identifying these regions preoperatively, virtually every pre-surgical decision from the surgical approach, operative goals (biopsy, sub-total vs. gross-total resection), and the potential need for awake craniotomy with intraoperative cortical-mapping is affected. Of the many techniques available to the surgeon, functional magnetic resonance imaging (fMRI) has become the primary modality of choice due to the ability of MRI to serve as a “one-stop shop” for assessing both anatomy and functionality of the brain. Given their prevalence, brain tumors serve as the model pathology for the included discussion; however, a similar case can be made for the use of fMRI in other neurological conditions, most notably epilepsy. The value of fMRI was validated in 2007 when the Centers for Medicare and Medicaid Services (CMS) established three new current procedural terminology (CPT) codes for clinical fMRI based upon its use for pre-therapeutic planning. In this article we will discuss the specific requirements for establishing an fMRI program, including specific software and hardware requirements. In addition, the nature of the fMRI CPT codes will be discussed. PMID:21435578

  19. Functional magnetic resonance imaging in chronic ischaemic stroke.

    PubMed

    Lake, Evelyn M R; Bazzigaluppi, Paolo; Stefanovic, Bojana

    2016-10-01

    Ischaemic stroke is the leading cause of adult disability worldwide. Effective rehabilitation is hindered by uncertainty surrounding the underlying mechanisms that govern long-term ischaemic injury progression. Despite its potential as a sensitive non-invasive in vivo marker of brain function that may aid in the development of new treatments, blood oxygenation level-dependent (BOLD) functional magnetic resonance imaging (fMRI) has found limited application in the clinical research on chronic stage stroke progression. Stroke affects each of the physiological parameters underlying the BOLD contrast, markedly complicating the interpretation of BOLD fMRI data. This review summarizes current progress on application of BOLD fMRI in the chronic stage of ischaemic injury progression and discusses means by which more information may be gained from such BOLD fMRI measurements. Concomitant measurements of vascular reactivity, neuronal activity and metabolism in preclinical models of stroke are reviewed along with illustrative examples of post-ischaemic evolution in neuronal, glial and vascular function. The realization of the BOLD fMRI potential to propel stroke research is predicated on the carefully designed preclinical research establishing an ischaemia-specific quantitative model of BOLD signal contrast to provide the framework for interpretation of fMRI findings in clinical populations.This article is part of the themed issue 'Interpreting BOLD: a dialogue between cognitive and cellular neuroscience'. PMID:27574307

  20. Wavelet smoothing of functional magnetic resonance images: a preliminary report

    NASA Astrophysics Data System (ADS)

    Lucier, Bradley J.

    2003-11-01

    Functional (time-dependent) Magnetic Resonance Imaging can be used to determine which parts of the brain are active during various limited activities; these parts of the brain are called activation regions. In this preliminary study we describe some experiments that are suggested from the following questions: Does one get improved results by analyzing the complex image data rather than just the real magnitude image data? Does wavelet shrinkage smoothing improve images? Should one smooth in time as well as within and between slices? If so, how should one model the relationship between time smoothness (or correlations) and spatial smoothness (or correlations). The measured data is really the Fourier coefficients of the complex image---should we remove noise in the Fourier domain before computing the complex images? In this preliminary study we describe some experiments related to these questions.

  1. A General Method for Calculating the External Magnetic Field from a Cylindrical Magnetic Source using Toroidal Functions

    SciTech Connect

    J Selvaggi; S Salon; O Kwon CVK Chari

    2006-02-14

    An alternative method is developed to compute the magnetic field from a circular cylindrical magnetic source. Specifically, a Fourier series expansion whose coefficients are toroidal functions is introduced which yields an alternative to the more familiar spherical harmonic solution or the Elliptic integral solution. This alternate formulation coupled with a method called charge simulation allows one to compute the external magnetic field from an arbitrary magnetic source in terms of a toroidal expansion. This expansion is valid on any finite hypothetical external observation cylinder. In other words, the magnetic scalar potential or the magnetic field intensity is computed on a exterior cylinder which encloses the magnetic source. This method can be used to accurately compute the far field where a finite element formulation is known to be inaccurate.

  2. Implementation and evaluation of simultaneous video-electroencephalography and functional magnetic resonance imaging.

    PubMed

    Chaudhary, Umair J; Kokkinos, Vasileios; Carmichael, David W; Rodionov, Roman; Gasston, David; Duncan, John S; Lemieux, Louis

    2010-10-01

    The objective of this study was to demonstrate that the addition of simultaneous and synchronised video to electroencephalography (EEG)-correlated functional magnetic resonance imaging (fMRI) could increase recorded information without data quality reduction. We investigated the effect of placing EEG, video equipment and their required power supplies inside the scanner room, on EEG, video and MRI data quality, and evaluated video-EEG-fMRI by modelling a hand motor task. Gradient-echo, echo-planner images (EPI) were acquired on a 3-T MRI scanner at variable camera positions in a test object [with and without radiofrequency (RF) excitation], and human subjects. EEG was recorded using a commercial MR-compatible 64-channel cap and amplifiers. Video recording was performed using a two-camera custom-made system with EEG synchronization. An in-house script was used to calculate signal to fluctuation noise ratio (SFNR) from EPI in test object with variable camera positions and in human subjects with and without concurrent video recording. Five subjects were investigated with video-EEG-fMRI while performing hand motor task. The fMRI time series data was analysed using statistical parametric mapping, by building block design general linear models which were paradigm prescribed and video based. Introduction of the cameras did not alter the SFNR significantly, nor did it show any signs of spike noise during RF off conditions. Video and EEG quality also did not show any significant artefact. The Statistical Parametric Mapping{T} maps from video based design revealed additional blood oxygen level-dependent responses in the expected locations for non-compliant subjects compared to the paradigm prescribed design. We conclude that video-EEG-fMRI set up can be implemented without affecting the data quality significantly and may provide valuable information on behaviour to enhance the analysis of fMRI data. PMID:20233646

  3. Surface functionalized magnetic nanoparticles for cancer therapy applications

    NASA Astrophysics Data System (ADS)

    Wydra, Robert John

    Despite recent advances, cancer remains the second leading cause of deaths in the United States. Magnetic nanoparticles have found various applications in cancer research as drug delivery platforms, enhanced contrast agents for improved diagnostic imaging, and the delivery of thermal energy as standalone therapy. Iron oxide nanoparticles absorb the energy from an alternating magnetic field and convert it into heat through Brownian and Neel relaxations. To better utilize magnetic nanoparticles for cancer therapy, surface functionalization is essential for such factors as decreasing cytotoxicity of healthy tissue, extending circulation time, specific targeting of cancer cells, and manage the controlled delivery of therapeutics. In the first study, iron oxide nanoparticles were coated with a poly(ethylene glycol) (PEG) based polymer shell. The PEG coating was selected to prevent protein adsorption and thus improve circulation time and minimize host response to the nanoparticles. Thermal therapy application feasibility was demonstrated in vitro with a thermoablation study on lung carcinoma cells. Building on the thermal therapy demonstration with iron oxide nanoparticles, the second area of work focused on intracellular delivery. Nanoparticles can be appropriately tailored to enter the cell and deliver energy on the nanoscale eliminating individual cancer cells. The underlying mechanism of action is still under study, and we were interested in determining the role of reactive oxygen species (ROS) catalytically generated from the surface of iron oxide nanoparticles in this measured cytotoxicity. When exposed to an AMF, the nanoscale heating effects are capable of enhancing the Fenton-like generation of ROS determined through a methylene blue degradation assay. To deliver this enhanced ROS effect to cells, monosaccharide coated nanoparticles were developed and successfully internalized by colon cancer cell lines. Upon AMF exposure, there was a measured increase in

  4. Functional connectivity magnetic resonance imaging classification of autism.

    PubMed

    Anderson, Jeffrey S; Nielsen, Jared A; Froehlich, Alyson L; DuBray, Molly B; Druzgal, T Jason; Cariello, Annahir N; Cooperrider, Jason R; Zielinski, Brandon A; Ravichandran, Caitlin; Fletcher, P Thomas; Alexander, Andrew L; Bigler, Erin D; Lange, Nicholas; Lainhart, Janet E

    2011-12-01

    Group differences in resting state functional magnetic resonance imaging connectivity between individuals with autism and typically developing controls have been widely replicated for a small number of discrete brain regions, yet the whole-brain distribution of connectivity abnormalities in autism is not well characterized. It is also unclear whether functional connectivity is sufficiently robust to be used as a diagnostic or prognostic metric in individual patients with autism. We obtained pairwise functional connectivity measurements from a lattice of 7266 regions of interest covering the entire grey matter (26.4 million connections) in a well-characterized set of 40 male adolescents and young adults with autism and 40 age-, sex- and IQ-matched typically developing subjects. A single resting state blood oxygen level-dependent scan of 8 min was used for the classification in each subject. A leave-one-out classifier successfully distinguished autism from control subjects with 83% sensitivity and 75% specificity for a total accuracy of 79% (P = 1.1 × 10(-7)). In subjects <20 years of age, the classifier performed at 89% accuracy (P = 5.4 × 10(-7)). In a replication dataset consisting of 21 individuals from six families with both affected and unaffected siblings, the classifier performed at 71% accuracy (91% accuracy for subjects <20 years of age). Classification scores in subjects with autism were significantly correlated with the Social Responsiveness Scale (P = 0.05), verbal IQ (P = 0.02) and the Autism Diagnostic Observation Schedule-Generic's combined social and communication subscores (P = 0.05). An analysis of informative connections demonstrated that region of interest pairs with strongest correlation values were most abnormal in autism. Negatively correlated region of interest pairs showed higher correlation in autism (less anticorrelation), possibly representing weaker inhibitory connections, particularly for long connections (Euclidean distance >10 cm

  5. Normal findings on brain FLAIR MRI scans at 3T

    PubMed Central

    Neema, Mohit; Guss, Zachary D.; Stankiewicz, James M.; Arora, Ashish; Healy, Brian C.; Bakshi, Rohit

    2010-01-01

    BACKGROUND AND PURPOSE Fluid attenuated inversion recovery (FLAIR) MR imaging of the brain has become a routine tool for assessing lesions in patients with suspected neurologic disorders. There is growing interest in 3T brain FLAIR MR imaging but little normative data are available. The purpose of this study was to evaluate the frequency and topography of cerebral hyperintensities seen with FLAIR MR imaging of the brain at 3T in a normal population and compare those findings to 1.5T. MATERIALS AND METHODS Whole-brain 2D FLAIR MR imaging was performed in 22 healthy controls (mean age, 44 ± 8 years; range, 30–53 years) at 3T. Fifteen of these subjects also underwent 2D FLAIR at 1.5T, with similar optimized parameters and voxel size. Cerebral hyperintense areas, including discrete foci, anterior and posterior periventricular capping, diffuse parenchymal hyperintensity, septal hyperintensity, corticospinal tract hyperintensity, and CSF flow artifacts were assessed. The Spearman rank test assessed the correlation between discrete hyperintense foci and age. The Wilcoxon signed rank test compared foci detectability at 3T versus 1.5T. RESULTS FLAIR at 3T commonly showed hyperintensities such as discrete foci (mean, 10.68 per subject; at least 1 present in 68% of subjects), anterior and posterior periventricular capping, diffuse posterior white matter hyperintensity, septal hyperintensity, corticospinal tract hyperintensity, and ventricular CSF flow artifacts. FLAIR at 3T showed a higher hyperintense foci volume (170 ± 243 versus 93 ± 152 mm3, P < .01) and number (9.4 ± 13 versus 5.5 ± 9.2, P < .01) than at 1.5T. No significant differences (P = .68) in the length/diameter of individual discrete hyperintense foci were seen between 3T and 1.5T. Discrete foci volume (r = 0.72 at 3T, r = 0.70 at 1.5T) and number (r = 0.74 at 3T; r = 0.69 at 1.5T) correlated with age to a similar degree on both platforms. All discrete foci were confined to the noncallosal supratentorial

  6. A design of novel type superconducting magnet for super-high field functional magnetic resonance imaging by using the harmonic analysis method of magnetic vector potentials

    NASA Astrophysics Data System (ADS)

    Zu, Dong-Lin; Guo, Hua; Song, Xiao-Yu; Bao, Shang-Lian

    2002-10-01

    The approach of expanding the magnetic scalar potential in a series of Legendre polynomials is suitable for designing a conventional superconducting magnetic resonance imaging magnet of distributed solenoidal configuration. Whereas the approach of expanding the magnetic vector potential in associated Legendre harmonics is suitable for designing a single-solenoid magnet that has multiple tiers, in which each tier may have multiple layers with different winding lengths. A set of three equations to suppress some of the lowest higher-order harmonics is found. As an example, a 4T single-solenoid magnetic resonance imaging magnet with 4×6 layers of superconducting wires is designed. The degree of homogeneity in the 0.5m diameter sphere volume is better than 5.8 ppm. The same degree of homogeneity is retained after optimal integralization of turns in each correction layer. The ratio Bm/B0 in the single-solenoid magnet is 30% lower than that in the conventional six-solenoid magnet. This tolerates higher rated superconducting current in the coil. The Lorentz force of the coil in the single-solenoid system is also much lower than in the six-solenoid system. This novel type of magnet possesses significant advantage over conventional magnets, especially when used as a super-high field functional magnetic resonance imaging magnet.

  7. Exploiting temporal information in functional magnetic resonance imaging brain data.

    PubMed

    Zhang, Lei; Samaras, Dimitris; Tomasi, Dardo; Alia-Klein, Nelly; Cottone, Lisa; Leskovjan, Andreana; Volkow, Nora; Goldstein, Rita

    2005-01-01

    Functional Magnetic Resonance Imaging(fMRI) has enabled scientists to look into the active human brain, leading to a flood of new data, thus encouraging the development of new data analysis methods. In this paper, we contribute a comprehensive framework for spatial and temporal exploration of fMRI data, and apply it to a challenging case study: separating drug addicted subjects from healthy non-drug-using controls. To our knowledge, this is the first time that learning on fMRI data is performed explicitly on temporal information for classification in such applications. Experimental results demonstrate that, by selecting discriminative features, group classification can be successfully performed on our case study although training data are exceptionally high dimensional, sparse and noisy fMRI sequences. The classification performance can be significantly improved by incorporating temporal information into machine learning. Both statistical and neuroscientific validation of the method's generalization ability are provided. We demonstrate that incorporation of computer science principles into functional neuroimaging clinical studies, facilitates deduction about the behavioral probes from the brain activation data, thus providing a valid tool that incorporates objective brain imaging data into clinical classification of psychopathologies and identification of genetic vulnerabilities. PMID:16685905

  8. Achromatic synesthesias - a functional magnetic resonance imaging study.

    PubMed

    Melero, H; Ríos-Lago, M; Peña-Melián, A; Álvarez-Linera, J

    2014-09-01

    Grapheme-color synesthetes experience consistent, automatic and idiosyncratic colors associated with specific letters and numbers. Frequently, these specific associations exhibit achromatic synesthetic qualities (e.g. white, black or gray). In this study, we have investigated for the first time the neural basis of achromatic synesthesias, their relationship to chromatic synesthesias and the achromatic congruency effect in order to understand not only synesthetic color but also other components of the synesthetic experience. To achieve this aim, functional magnetic resonance imaging experiments were performed in a group of associator grapheme-color synesthetes and matched controls who were stimulated with real chromatic and achromatic stimuli (Mondrians), and with letters and numbers that elicited different types of grapheme-color synesthesias (i.e. chromatic and achromatic inducers which elicited chromatic but also achromatic synesthesias, as well as congruent and incongruent ones). The information derived from the analysis of Mondrians and chromatic/achromatic synesthesias suggests that real and synesthetic colors/achromaticity do not fully share neural mechanisms. The whole-brain analysis of BOLD signals in response to the complete set of synesthetic inducers revealed that the functional peculiarities of the synesthetic brain are distributed, and reflect different components of the synesthetic experience: a perceptual component, an (attentional) feature binding component, and an emotional component. Additionally, the inclusion of achromatic experiences has provided new evidence in favor of the emotional binding theory, a line of interpretation which constitutes a bridge between grapheme-color synesthesia and other developmental modalities of the phenomenon. PMID:24845620

  9. Structural and functional magnetic resonance imaging of autism spectrum disorders

    PubMed Central

    Stigler, Kimberly A.; McDonald, Brenna C.; Anand, Amit; Saykin, Andrew J.; McDougle, Christopher J.

    2011-01-01

    The neurobiology of autism spectrum disorders (ASDs) has become increasingly understood since the advent of magnetic resonance imaging (MRI). Initial observations of an above-average head circumference were supported by structural MRI studies that found evidence of increased total brain volume and early rapid brain overgrowth in affected individuals. Subsequent research revealed consistent abnormalities in cortical gray and white matter volume in ASDs. The structural integrity and orientation of white matter have been further elucidated via diffusion tensor imaging methods. The emergence of functional MRI techniques led to an enhanced understanding of the neural circuitry of ASDs, demonstrating areas of dysfunctional cortical activation and atypical cortical specialization. These studies have provided evidence of underconnectivity in distributed cortical networks integral to the core impairments associated with ASDs. Abnormalities in the default-mode network during the resting state have also been identified. Overall, structural and functional MRI research has generated important insights into the neurobiology of ASDs. Additional research is needed to further delineate the underlying brain basis of this constellation of disorders. PMID:21130750

  10. Methodological challenges and solutions in auditory functional magnetic resonance imaging.

    PubMed

    Peelle, Jonathan E

    2014-01-01

    Functional magnetic resonance imaging (fMRI) studies involve substantial acoustic noise. This review covers the difficulties posed by such noise for auditory neuroscience, as well as a number of possible solutions that have emerged. Acoustic noise can affect the processing of auditory stimuli by making them inaudible or unintelligible, and can result in reduced sensitivity to auditory activation in auditory cortex. Equally importantly, acoustic noise may also lead to increased listening effort, meaning that even when auditory stimuli are perceived, neural processing may differ from when the same stimuli are presented in quiet. These and other challenges have motivated a number of approaches for collecting auditory fMRI data. Although using a continuous echoplanar imaging (EPI) sequence provides high quality imaging data, these data may also be contaminated by background acoustic noise. Traditional sparse imaging has the advantage of avoiding acoustic noise during stimulus presentation, but at a cost of reduced temporal resolution. Recently, three classes of techniques have been developed to circumvent these limitations. The first is Interleaved Silent Steady State (ISSS) imaging, a variation of sparse imaging that involves collecting multiple volumes following a silent period while maintaining steady-state longitudinal magnetization. The second involves active noise control to limit the impact of acoustic scanner noise. Finally, novel MRI sequences that reduce the amount of acoustic noise produced during fMRI make the use of continuous scanning a more practical option. Together these advances provide unprecedented opportunities for researchers to collect high-quality data of hemodynamic responses to auditory stimuli using fMRI. PMID:25191218

  11. Spontaneous physiological variability modulates dynamic functional connectivity in resting-state functional magnetic resonance imaging.

    PubMed

    Nikolaou, F; Orphanidou, C; Papakyriakou, P; Murphy, K; Wise, R G; Mitsis, G D

    2016-05-13

    It is well known that the blood oxygen level-dependent (BOLD) signal measured by functional magnetic resonance imaging (fMRI) is influenced-in addition to neuronal activity-by fluctuations in physiological signals, including arterial CO2, respiration and heart rate/heart rate variability (HR/HRV). Even spontaneous fluctuations of the aforementioned physiological signals have been shown to influence the BOLD fMRI signal in a regionally specific manner. Related to this, estimates of functional connectivity between different brain regions, performed when the subject is at rest, may be confounded by the effects of physiological signal fluctuations. Moreover, resting functional connectivity has been shown to vary with respect to time (dynamic functional connectivity), with the sources of this variation not fully elucidated. In this context, we examine the relation between dynamic functional connectivity patterns and the time-varying properties of simultaneously recorded physiological signals (end-tidal CO2 and HR/HRV) using resting-state fMRI measurements from 12 healthy subjects. The results reveal a modulatory effect of the aforementioned physiological signals on the dynamic resting functional connectivity patterns for a number of resting-state networks (default mode network, somatosensory, visual). By using discrete wavelet decomposition, we also show that these modulation effects are more pronounced in specific frequency bands. PMID:27044987

  12. Functional magnetic resonance imaging of internet addiction in young adults

    PubMed Central

    Sepede, Gianna; Tavino, Margherita; Santacroce, Rita; Fiori, Federica; Salerno, Rosa Maria; Di Giannantonio, Massimo

    2016-01-01

    AIM: To report the results of functional magnetic resonance imaging (fMRI) studies pertaining internet addiction disorder (IAD) in young adults. METHODS: We conducted a systematic review on PubMed, focusing our attention on fMRI studies involving adult IAD patients, free from any comorbid psychiatric condition. The following search words were used, both alone and in combination: fMRI, internet addiction, internet dependence, functional neuroimaging. The search was conducted on April 20th, 2015 and yielded 58 records. Inclusion criteria were the following: Articles written in English, patients’ age ≥ 18 years, patients affected by IAD, studies providing fMRI results during resting state or cognitive/emotional paradigms. Structural MRI studies, functional imaging techniques other than fMRI, studies involving adolescents, patients with comorbid psychiatric, neurological or medical conditions were excluded. By reading titles and abstracts, we excluded 30 records. By reading the full texts of the 28 remaining articles, we identified 18 papers meeting our inclusion criteria and therefore included in the qualitative synthesis. RESULTS: We found 18 studies fulfilling our inclusion criteria, 17 of them conducted in Asia, and including a total number of 666 tested subjects. The included studies reported data acquired during resting state or different paradigms, such as cue-reactivity, guessing or cognitive control tasks. The enrolled patients were usually males (95.4%) and very young (21-25 years). The most represented IAD subtype, reported in more than 85% of patients, was the internet gaming disorder, or videogame addiction. In the resting state studies, the more relevant abnormalities were localized in the superior temporal gyrus, limbic, medial frontal and parietal regions. When analyzing the task related fmri studies, we found that less than half of the papers reported behavioral differences between patients and normal controls, but all of them found significant

  13. Mapping Depression in Schizophrenia: A Functional Magnetic Resonance Imaging Study

    PubMed Central

    Kumari, Veena; Peters, Emmanuelle; Guinn, Ashley; Fannon, Dominic; Russell, Tamara; Sumich, Alexander; Kuipers, Elizabeth; Williams, Steven C. R.; ffytche, Dominic H.

    2016-01-01

    Depressive symptoms are common in schizophrenia, often left untreated, and associated with a high relapse rate, suicidal ideation, increased mortality, reduced social adjustment and poor quality of life. The neural mechanisms underlying depression in psychosis are poorly understood. Given reports of altered brain response to negative facial affect in depressive disorders, we examined brain response to emotive facial expressions in relation to levels of depression in people with psychosis. Seventy outpatients (final N = 63) and 20 healthy participants underwent functional magnetic resonance imaging during an implicit affect processing task involving presentation of facial expressions of fear, anger, happiness as well as neutral expressions and a (no face) control condition. All patients completed Beck Depression Inventory (BDI-II) and had their symptoms assessed on the Positive and Negative Syndrome Scale (PANSS). In patients, depression (BDI-II) scores associated positively with activation of the left thalamus, extending to the putamen-globus pallidus, insula, inferior-middle frontal and para-post-pre-central gyri during fearful expressions. Furthermore, patients with moderate-to-severe depression had significantly higher activity in these brain regions during fearful expressions relative to patients with no, minimal, or mild depression and healthy participants. The study provides first evidence of enhanced brain response to fearful facial expressions, which signal an uncertain source of threat in the environment, in patients with psychosis and a high level of self-reported depression. PMID:26712855

  14. [Functional magnetic resonance imaging and dynamic neuroanatomy of addictive disorders].

    PubMed

    Mel'nikov, M E; Shtark, M B

    2014-01-01

    Research into the cerebral patterns that govern the formation and development of addictive behavior is one of the most interesting goals of neurophysiology. Authors of contemporary papers on the matter define a number of symptoms that are all part of substance or non-substance dependence, each one of them leading to abnormalities in the corresponding system of the brain. During the last twenty years the functional magnetic resonance imaging (fMR1) technology has been instrumental in locating such abnormalities, identifying specific parts of the brain that, when dysfunctional, may enhance addiction and cause its positive or negative symptoms. This article reviews fMRI studies aimed toward locating areas in the brain that are responsible for cognitive, emotional, and motivational dysfunction. Cerebral correlatives of impulsiveness, behavior control, and drug cravings are reviewed separately. The article also contains an overview of possibilities to further investigate the Selves of those dependent on substances, identify previously unknown diagnostic markers of substance dependence, and evaluate the effectiveness of therapy. The research under review in this article provides data that points to a special role of the nucleus caudatus as well as the nucleus accumbens, the thalamus, the insular cortex (IC), the anterior cingulate, prefrontal and orbitofrontal areas in psychological disorders that are part of substance dependence. General findings of the article are in accordance with contemporary models of addictive pattern. PMID:25729844

  15. Multi-function magnetic jack control drive mechanism

    DOEpatents

    Bollinger, Lawrence R.; Crawford, Donald C.

    1986-01-01

    A multi-function magnetic jack control drive mechanism for controlling a nuclear reactor is provided. The mechanism includes an elongate pressure housing in which a plurality of closely spaced drive rods are located. Each drive rod is connected to a rod which is insertable in the reactor core. An electromechanical stationary latch device is provided which is actuatable to hold each drive rod stationary with respect to the pressure housing. An electromechanical movable latch device is also provided for each one of the drive rods. Each movable latch device is provided with a base and is actuatable to hold a respective drive rod stationary with respect to the base. An electromechanical lift device is further provided for each base which is actuatable for moving a respective base longitudinally along the pressure housing. In this manner, one or more drive rods can be moved in the pressure housing by sequentially and repetitively operating the electromechanical devices. Preferably, each latch device includes a pair of opposed latches which grip teeth located on the respective drive rod. Two, three, or four drive rods can be located symmetrically about the longitudinal axis of the pressure housing.

  16. Multi-function magnetic jack control drive mechanism

    DOEpatents

    Bollinger, L.R.; Crawford, D.C.

    1983-10-06

    A multi-function magnetic jack control drive mechanism for controlling a nuclear reactor is provided. The mechanism includes an elongate pressure housing in which a plurality of closely spaced drive rods are located. Each drive rod is connected to a rod which is insertable in the reactor core. An electromechanical stationary latch device is provided which is actuatable to hold each drive rod stationary with respect to the pressure housing. An electromechanical movable latch device is also provided for each one of the drive rods. Each movable latch device is provided with a base and is actuatable to hold a respective drive rod stationary with respect to the base. An electromechanical lift device is further provided for each base which is actuatable for moving a respective base longitudinally along the pressure housing. In this manner, one or more drive rods can be moved in the pressure housing by sequentially and repetitively operating the electromechanical devices. Preferably, each latch device includes a pair of opposed latches which grip teeth located on the respective drive rod. Two, three, or four drive rods can be located symmetrically about the longitudinal axis of the pressure housing.

  17. Mapping Depression in Schizophrenia: A Functional Magnetic Resonance Imaging Study.

    PubMed

    Kumari, Veena; Peters, Emmanuelle; Guinn, Ashley; Fannon, Dominic; Russell, Tamara; Sumich, Alexander; Kuipers, Elizabeth; Williams, Steven C R; Ffytche, Dominic H

    2016-05-01

    Depressive symptoms are common in schizophrenia, often left untreated, and associated with a high relapse rate, suicidal ideation, increased mortality, reduced social adjustment and poor quality of life. The neural mechanisms underlying depression in psychosis are poorly understood. Given reports of altered brain response to negative facial affect in depressive disorders, we examined brain response to emotive facial expressions in relation to levels of depression in people with psychosis. Seventy outpatients (final N= 63) and 20 healthy participants underwent functional magnetic resonance imaging during an implicit affect processing task involving presentation of facial expressions of fear, anger, happiness as well as neutral expressions and a (no face) control condition. All patients completed Beck Depression Inventory (BDI-II) and had their symptoms assessed on the Positive and Negative Syndrome Scale (PANSS). In patients, depression (BDI-II) scores associated positively with activation of the left thalamus, extending to the putamen-globus pallidus, insula, inferior-middle frontal and para-post-pre-central gyri during fearful expressions. Furthermore, patients with moderate-to-severe depression had significantly higher activity in these brain regions during fearful expressions relative to patients with no, minimal, or mild depression and healthy participants. The study provides first evidence of enhanced brain response to fearful facial expressions, which signal an uncertain source of threat in the environment, in patients with psychosis and a high level of self-reported depression. PMID:26712855

  18. Bilingual brain organization: a functional magnetic resonance adaptation study.

    PubMed

    Klein, Denise; Zatorre, Robert J; Chen, Jen-Kai; Milner, Brenda; Crane, Joelle; Belin, Pascal; Bouffard, Marc

    2006-05-15

    We used functional magnetic resonance adaptation (fMRA) to examine whether intra-voxel functional specificity may be present for first (L1)- and second (L2)-language processing. We examined within- and across-language adaptation for spoken words in English-French bilinguals who had acquired their L2 after the age of 4 years. Subjects listened to words presented binaurally through earphones. In two control conditions (one for each language), six identical words were presented to obtain maximal adaptation. The remaining six conditions each consisted of five words that were identical followed by a sixth word that differed. There were thus a total of eight experimental conditions: no-change (sixth word identical to first five); a change in meaning (different final word in L1); a change in language (final item translated into L2); a change in meaning and language (different final word in L2). The same four conditions were presented in L2. The study also included a silent baseline. At the neural level, within- and across-language word changes resulted in release from adaptation. This was true for separate analyses of L1 and L2. We saw no evidence for greater recovery from adaptation in across-language relative to within-language conditions. While many brain regions were common to L1 and L2, we did observe differences in adaptation for forward translation (L1 to L2) as compared to backward translation (L2 to L1). The results support the idea that, at the lexical level, the neural substrates for L1 and L2 in bilinguals are shared, but with some populations of neurons within these shared regions showing language-specific responses. PMID:16460968

  19. Cerebellum and speech perception: a functional magnetic resonance imaging study.

    PubMed

    Mathiak, Klaus; Hertrich, Ingo; Grodd, Wolfgang; Ackermann, Hermann

    2002-08-15

    A variety of data indicate that the cerebellum participates in perceptual tasks requiring the precise representation of temporal information. Access to the word form of a lexical item requires, among other functions, the processing of durational parameters of verbal utterances. Therefore, cerebellar dysfunctions must be expected to impair word recognition. In order to specify the topography of the assumed cerebellar speech perception mechanism, a functional magnetic resonance imaging study was performed using the German lexical items "Boden" ([bodn], Engl. "floor") and "Boten" ([botn], "messengers") as test materials. The contrast in sound structure of these two lexical items can be signaled either by the length of the wordmedial pause (closure time, CLT; an exclusively temporal measure) or by the aspiration noise of wordmedial "d" or "t" (voice onset time, VOT; an intrasegmental cue). A previous study found bilateral cerebellar disorders to compromise word recognition based on CLT whereas the encoding of VOT remained unimpaired. In the present study, two series of "Boden - Boten" utterances were resynthesized, systematically varying either in CLT or VOT. Subjects had to identify both words "Boden" and "Boten" by analysis of either the durational parameter CLT or the VOT aspiration segment. In a subtraction design, CLT categorization as compared to VOT identification (CLT - VOT) yielded a significant hemodynamic response of the right cerebellar hemisphere (neocerebellum Crus I) and the frontal lobe (anterior to Broca's area). The reversed contrast ( VOT - CLT) resulted in a single activation cluster located at the level of the supratemporal plane of the dominant hemisphere. These findings provide first evidence for a distinct contribution of the right cerebellar hemisphere to speech perception in terms of encoding of durational parameters of verbal utterances. Verbal working memory tasks, lexical response selection, and auditory imagery of word strings have been

  20. Altered executive function in the welders: A functional magnetic resonance imaging study.

    PubMed

    Seo, Jeehye; Chang, Yongmin; Jang, Kyung Eun; Park, Jang Woo; Kim, Yang-Tae; Park, Sin-Jae; Jeong, Kyoung Sook; Kim, Ahro; Kim, Suk Hwan; Kim, Yangho

    2016-01-01

    Chronic exposure to manganese (Mn) can lead to impairments in motor and cognitive functions. Several recent studies reported Mn-induced executive dysfunction. The present study compared the neural correlates of ongoing executive function of welders and healthy controls. Fifty-three welders and 44 healthy controls were enrolled. Participants were given functional magnetic resonance imaging (fMRI) scans and performed two modified versions of the Wisconsin Card Sorting Task (WCST) that differed in cognitive demand, and a task that established a high-level baseline (HLB) condition. Card Sorting Test and Word-Color Test were also used to assess executive performance. Neural activation of the bilateral superior-frontal cortex, right-inferior parietal cortex, and bilateral insula cortex were greater in healthy controls than in welders when contrasting the difficult version of the WCST with the HLB. There were also correlations between executive functions by the Card Sorting Test and Word-Color Test, and brain activation in the insula cortex using the WCST. Our results indicated that welders had altered neural processing related to executive function in the prefrontal cortex under conditions of high cognitive demand. Welders also had less activation of the insula cortex, a part of a larger network comprising the lateral prefrontal cortex and parietal cortex. PMID:27208889

  1. Multi-Parametric Neuroimaging Reproducibility: A 3T Resource Study

    PubMed Central

    Landman, Bennett A.; Huang, Alan J.; Gifford, Aliya; Vikram, Deepti S.; Lim, Issel Anne L.; Farrell, Jonathan A.D.; Bogovic, John A.; Hua, Jun; Chen, Min; Jarso, Samson; Smith, Seth A.; Joel, Suresh; Mori, Susumu; Pekar, James J.; Barker, Peter B.; Prince, Jerry L.; van Zijl, Peter C.M.

    2010-01-01

    Modern MRI image processing methods have yielded quantitative, morphometric, functional, and structural assessments of the human brain. These analyses typically exploit carefully optimized protocols for specific imaging targets. Algorithm investigators have several excellent public data resources to use to test, develop, and optimize their methods. Recently, there has been an increasing focus on combining MRI protocols in multi-parametric studies. Notably, these have included innovative approaches for fusing connectivity inferences with functional and/or anatomical characterizations. Yet, validation of the reproducibility of these interesting and novel methods has been severely hampered by the limited availability of appropriate multi-parametric data. We present an imaging protocol optimized to include state-of-the-art assessment of brain function, structure, micro-architecture, and quantitative parameters within a clinically feasible 60 minute protocol on a 3T MRI scanner. We present scan-rescan reproducibility of these imaging contrasts based on 21 healthy volunteers (11 M/10 F, 22–61 y/o). The cortical gray matter, cortical white matter, ventricular cerebrospinal fluid, thalamus, putamen, caudate, cerebellar gray matter, cerebellar white matter, and brainstem were identified with mean volume-wise reproducibility of 3.5%. We tabulate the mean intensity, variability and reproducibility of each contrast in a region of interest approach, which is essential for prospective study planning and retrospective power analysis considerations. Anatomy was highly consistent on structural acquisition (~1–5% variability), while variation on diffusion and several other quantitative scans was higher (~<10%). Some sequences are particularly variable in specific structures (ASL exhibited variation of 28% in the cerebral white matter) or in thin structures (quantitative T2 varied by up to 73% in the caudate) due, in large part, to variability in automated ROI placement. The

  2. Cavernosal nerve functionality evaluation after magnetic resonance imaging-guided transurethral ultrasound treatment of the prostate

    PubMed Central

    Sammet, Steffen; Partanen, Ari; Yousuf, Ambereen; Sammet, Christina L; Ward, Emily V; Wardrip, Craig; Niekrasz, Marek; Antic, Tatjana; Razmaria, Aria; Farahani, Keyvan; Sokka, Shunmugavelu; Karczmar, Gregory; Oto, Aytekin

    2015-01-01

    AIM: To evaluate the feasibility of using therapeutic ultrasound as an alternative treatment option for organ-confined prostate cancer. METHODS: In this study, a trans-urethral therapeutic ultrasound applicator in combination with 3T magnetic resonance imaging (MRI) guidance was used for real-time multi-planar MRI-based temperature monitoring and temperature feedback control of prostatic tissue thermal ablation in vivo. We evaluated the feasibility and safety of MRI-guided trans-urethral ultrasound to effectively and accurately ablate prostate tissue while minimizing the damage to surrounding tissues in eight canine prostates. MRI was used to plan sonications, monitor temperature changes during therapy, and to evaluate treatment outcome. Real-time temperature and thermal dose maps were calculated using the proton resonance frequency shift technique and were displayed as two-dimensional color-coded overlays on top of the anatomical images. After ultrasound treatment, an evaluation of the integrity of cavernosal nerves was performed during prostatectomy with a nerve stimulator that measured tumescence response quantitatively and indicated intact cavernous nerve functionality. Planned sonication volumes were visually correlated to MRI ablation volumes and corresponding histo-pathological sections after prostatectomy. RESULTS: A total of 16 sonications were performed in 8 canines. MR images acquired before ultrasound treatment were used to localize the prostate and to prescribe sonication targets in all canines. Temperature elevations corresponded within 1 degree of the targeted sonication angle, as well as with the width and length of the active transducer elements. The ultrasound treatment procedures were automatically interrupted when the temperature in the target zone reached 56 °C. In all canines erectile responses were evaluated with a cavernous nerve stimulator post-treatment and showed a tumescence response after stimulation with an electric current. These

  3. A time-dependent density functional theory investigation on the nature of the electronic transitions involved in the nonlinear optical response of [Ru(CF3CO2)3T] (T = 4'-(C6H4-p-NBu2)-2,2':6',2''-terpyridine).

    PubMed

    De Angelis, Filippo; Fantacci, Simona; Sgamelotti, Antonio; Cariati, Franco; Roberto, Dominique; Tessore, Francesca; Ugo, Renato

    2006-02-14

    We report a theoretical study based on density functional theory (DFT) and time-dependent DFT (TDDFT) calculations on the nature and role of the absorption bands involved in the nonlinear optical response of the complexes [Ru(CF3CO2)3T] (T = T1, T2; T1 = 4'-(C6H4-p-NBu2)-2,2':6',2''-terpyridine, T2 = 4'-(C6H4-p-NMe2)-2,2':6',2''-terpyridine). Geometry optimizations, performed without any symmetry constraints, confirm a twisting of the -C6H4-p-NBu2 moiety with respect to the plane of the chelated terpyridine. Despite this lack of strong pi interaction, TDDFT excited states calculations of the electronic spectrum in solution provide evidence of a relevant role of the NBu2 donor group in the low-energy LMCT band at 911 nm. Calculations also show that the two bands at higher energy (508 and 455 nm) are not attributable only to LMCT and ILCT transitions but to a mixing of ILCT/MLCT and ILCT/pi-pi* transitions, respectively. The 911 nm LMCT band, appearing at lower wavelength of the second harmonic (670 nm) of the EFISH experiment, controls the negative value of the second-order NLO response. This is confirmed by our calculations of the static component beta0(zzz) of the quadratic hyperpolarizability tensor, showing a large positive value. In addition we have found that the increase of the dipole moment upon excitation occurs, in all the characterized transitions, along the dipole moment axis, thus explaining why the EFISH and solvatochromic experimental values of the quadratic hyperpolarizability agree as sign and value. PMID:16437181

  4. Magnetically Actuated Soft Capsule With the Multimodal Drug Release Function.

    PubMed

    Yim, Sehyuk; Goyal, Kartik; Sitti, Metin

    2013-01-01

    In this paper, we present a magnetically actuated multimodal drug release mechanism using a tetherless soft capsule endoscope for the treatment of gastric disease. Because the designed capsule has a drug chamber between both magnetic heads, if it is compressed by the external magnetic field, the capsule could release a drug in a specific position locally. The capsule is designed to release a drug in two modes according to the situation. In the first mode, a small amount of drug is continuously released by a series of pulse type magnetic field (0.01-0.03 T). The experimental results show that the drug release can be controlled by the frequency of the external magnetic pulse. In the second mode, about 800 mm(3) of drug is released by the external magnetic field of 0.07 T, which induces a stronger magnetic attraction than the critical force for capsule's collapsing. As a result, a polymeric coating is formed around the capsule. The coated area is dependent on the drug viscosity. This paper presents simulations and various experiments to evaluate the magnetically actuated multimodal drug release capability. The proposed soft capsules could be used as minimally invasive tetherless medical devices with therapeutic capability for the next generation capsule endoscopy. PMID:25378896

  5. Theory of multichannel magnetic stimulation: toward functional neuromuscular rehabilitation.

    PubMed

    Ruohonen, J; Ravazzani, P; Grandori, F; Ilmoniemi, R J

    1999-06-01

    Human excitable cells can be stimulated noninvasively with externally applied time-varying electromagnetic fields. The stimulation can be achieved either by directly driving current into the tissue (electrical stimulation) or by means of electro-magnetic induction (magnetic stimulation). While the electrical stimulation of the peripheral neuromuscular system has many beneficial applications, peripheral magnetic stimulation has so far only a few. This paper analyzes theoretically the use of multiple magnetic stimulation coils to better control the excitation and also to eventually mimic electrical stimulation. Multiple coils allow electronic spatial adjustment of the shape and location of the stimulus without moving the coils. The new properties may enable unforeseen uses for peripheral magnetic stimulation, e.g., in rehabilitation of patients with neuromuscular impairment. PMID:10356871

  6. What is feasible with imaging human brain function and connectivity using functional magnetic resonance imaging.

    PubMed

    Ugurbil, Kamil

    2016-10-01

    When we consider all of the methods we employ to detect brain function, from electrophysiology to optical techniques to functional magnetic resonance imaging (fMRI), we do not really have a 'golden technique' that meets all of the needs for studying the brain. We have methods, each of which has significant limitations but provide often complimentary information. Clearly, there are many questions that need to be answered about fMRI, which unlike other methods, allows us to study the human brain. However, there are also extraordinary accomplishments or demonstration of the feasibility of reaching new and previously unexpected scales of function in the human brain. This article reviews some of the work we have pursued, often with extensive collaborations with other co-workers, towards understanding the underlying mechanisms of the methodology, defining its limitations, and developing solutions to advance it. No doubt, our knowledge of human brain function has vastly expanded since the introduction of fMRI. However, methods and instrumentation in this dynamic field have evolved to a state that discoveries about the human brain based on fMRI principles, together with information garnered at a much finer spatial and temporal scale through other methods, are poised to significantly accelerate in the next decade.This article is part of the themed issue 'Interpreting BOLD: a dialogue between cognitive and cellular neuroscience'. PMID:27574313

  7. The nuclear magnetic shielding as a function of internuclear separation

    NASA Astrophysics Data System (ADS)

    Jameson, Cynthia J.; de Dios, Angel C.

    1993-02-01

    Ab initio calculations of nuclear magnetic shielding surfaces for 23Na in the NaH molecule, 39Ar in ArNe, 21Ne in NeHe, and 39Ar in Ar...NaH are carried out over a wide range of internuclear separations, using a local origin method (LORG) which damps out the long-range errors due to incomplete basis sets. The R dependence of the intermolecular shielding in the attractive region of the potential in these systems and in Ar...Ar and Ar...Na+ are consistent with the long-range limiting forms associated with the shielding hyperpolarizability in conjunction with a mean square electric field approximation. The Cl and F shieldings over the range of nuclear displacements spanning the classical turning points of the ground vibrational states of ClF and F2 are found to be remarkably superposable upon scaling by the factors ṡRe. This holds as well for ClH compared with FH. The shielding of 23Na and 7Li in NaH and LiH molecules are almost superposable. These and the scaling of the intermolecular shielding in rare gas pairs indicate some general similarities of shielding surfaces. The systematic variation in the signs and magnitudes of the first derivative of X nuclear shielding at the equilibrium geometry in XHn molecules of the first and second row of the Periodic Table are shown to be consistent with a general shape for the shielding function σ(R), which we have found in rare gas pairs and for 23Na in NaH.

  8. Nuclear magnetic resonance imaging and spectroscopy of human brain function.

    PubMed Central

    Shulman, R G; Blamire, A M; Rothman, D L; McCarthy, G

    1993-01-01

    The techniques of in vivo magnetic resonance (MR) imaging and spectroscopy have been established over the past two decades. Recent applications of these methods to study human brain function have become a rapidly growing area of research. The development of methods using standard MR contrast agents within the cerebral vasculature has allowed measurements of regional cerebral blood volume (rCBV), which are activity dependent. Subsequent investigations linked the MR relaxation properties of brain tissue to blood oxygenation levels which are also modulated by consumption and blood flow (rCBF). These methods have allowed mapping of brain activity in human visual and motor cortex as well as in areas of the frontal lobe involved in language. The methods have high enough spatial and temporal sensitivity to be used in individual subjects. MR spectroscopy of proton and carbon-13 nuclei has been used to measure rates of glucose transport and metabolism in the human brain. The steady-state measurements of brain glucose concentrations can be used to monitor the glycolytic flux, whereas subsequent glucose metabolism--i.e., the flux into the cerebral glutamate pool--can be used to measure tricarboxylic acid cycle flux. Under visual stimulation the concentration of lactate in the visual cortex has been shown to increase by MR spectroscopy. This increase is compatible with an increase of anaerobic glycolysis under these conditions as earlier proposed from positron emission tomography studies. It is shown how MR spectroscopy can extend this understanding of brain metabolism. Images Fig. 1 Fig. 2 Fig. 3 PMID:8475050

  9. Investigating short-range magnetism in strongly correlated materials via magnetic pair distribution function analysis and ab initio theory

    NASA Astrophysics Data System (ADS)

    Frandsen, Benjamin; Page, Katharine; Brunelli, Michela; Staunton, Julie; Billinge, Simon

    Short-range magnetic correlations are known to exist in a variety of strongly correlated electron systems, but our understanding of the role they play is challenged by the difficulty of experimentally probing such correlations. Magnetic pair distribution function (mPDF) analysis is a newly developed neutron total scattering method that can reveal short-range magnetic correlations directly in real space, and may therefore help ameliorate this difficulty. We present temperature-dependent mPDF measurements of the short-range magnetic correlations in the paramagnetic phase of antiferromagnetic MnO, an archetypal strongly correlated transition-metal oxide. We observe significant correlations on a ~1 nm length scale that differ substantially from the low-temperature long-range-ordered spin arrangement. With no free parameters, ab initio calculations using the self-interaction-corrected local spin density approximation of density functional theory quantitatively reproduce the magnetic correlations to a high degree of accuracy. These results yield valuable insight into the magnetic exchange in MnO and showcase the utility of the mPDF technique for studying magnetic properties of strongly correlated electron systems.

  10. Visual evoked potential (VEP) measured by simultaneous 64-channel EEG and 3T fMRI.

    PubMed

    Bonmassar, G; Anami, K; Ives, J; Belliveau, J W

    1999-06-23

    We present the first simultaneous measurements of evoked potentials (EPs) and fMRI hemodynamic responses to visual stimulation. Visual evoked potentials (VEPs) were recorded both inside and outside the static 3T magnetic field, and during fMRI examination. We designed, constructed, and tested a non-magnetic 64-channel EEG recording cap. By using a large number of EEG channels it is possible to design a spatial filter capable of removing the artifact noise present when recording EEG/EPs within a strong magnetic field. We show that the designed spatial filter is capable of recovering the ballistocardiogram-contaminated original EEG signal. Isopotential plots of the electrode array recordings at the peak of the VEP response (approximately 100ms) correspond well with simultaneous fMRI observed activated areas of primary and secondary visual cortices. PMID:10501528

  11. Lectin-functionalized magnetic iron oxide nanoparticles for reproductive improvement

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Background: Semen ejaculates contain heterogeneous sperm populations that can jeopardize male fertility. Recent development of nanotechnology in physiological systems may have applications in reproductive biology. Here, we used magnetic nanoparticles as a novel strategy for sperm purification to imp...

  12. Biomedical Applications of Magnetically Functionalized Organic/Inorganic Hybrid Nanofibers.

    PubMed

    Lee, Hwa-Jeong; Lee, Sang Joon; Uthaman, Saji; Thomas, Reju George; Hyun, Hoon; Jeong, Yong Yeon; Cho, Chong-Su; Park, In-Kyu

    2015-01-01

    Nanofibers are one-dimensional nanomaterial in fiber form with diameter less than 1 µm and an aspect ratio (length/diameter) larger than 100:1. Among the different types of nanoparticle-loaded nanofiber systems, nanofibers loaded with magnetic nanoparticles have gained much attention from biomedical scientists due to a synergistic effect obtained from the unique properties of both the nanofibers and magnetic nanoparticles. These magnetic nanoparticle-encapsulated or -embedded nanofiber systems can be used not only for imaging purposes but also for therapy. In this review, we focused on recent advances in nanofibers loaded with magnetic nanoparticles, their biomedical applications, and future trends in the application of these nanofibers. PMID:26084046

  13. Biomedical Applications of Magnetically Functionalized Organic/Inorganic Hybrid Nanofibers

    PubMed Central

    Lee, Hwa-Jeong; Lee, Sang Joon; Uthaman, Saji; Thomas, Reju George; Hyun, Hoon; Jeong, Yong Yeon; Cho, Chong-Su; Park, In-Kyu

    2015-01-01

    Nanofibers are one-dimensional nanomaterial in fiber form with diameter less than 1 µm and an aspect ratio (length/diameter) larger than 100:1. Among the different types of nanoparticle-loaded nanofiber systems, nanofibers loaded with magnetic nanoparticles have gained much attention from biomedical scientists due to a synergistic effect obtained from the unique properties of both the nanofibers and magnetic nanoparticles. These magnetic nanoparticle-encapsulated or -embedded nanofiber systems can be used not only for imaging purposes but also for therapy. In this review, we focused on recent advances in nanofibers loaded with magnetic nanoparticles, their biomedical applications, and future trends in the application of these nanofibers. PMID:26084046

  14. Dual-function magnetic structure for toroidal plasma devices

    DOEpatents

    Brown, Robert L.

    1978-01-01

    This invention relates to a support system wherein the iron core and yoke of the plasma current system of a tokamak plasma containment device is redesigned to support the forces of the magnet coils. The containment rings, which occupy very valuable space around the magnet coils, are utilized to serve as yokes for the core such that the conventional yoke is eliminated. The overall result is an improved aspect ratio, reduction in structure, smaller overall size, and improved access to the plasma ring.

  15. Magnetic nanoparticles: synthesis, functionalization, and applications in bioimaging and magnetic energy storage

    PubMed Central

    Frey, Natalie A.; Peng, Sheng; Cheng, Kai; Sun, Shouheng

    2009-01-01

    This tutorial review summarizes the recent advances in the chemical synthesis and potential applications of monodisperse magnetic nanoparticles. After a brief introduction to nanomagnetism, the review focuses on recent developments in solution phase syntheses of monodisperse MFe2O4, Co, Fe, CoFe, FePt and SmCo5 nanoparticles. The review further outlines the surface, structural, and magnetic properties of these nanoparticles for biomedicine and magnetic energy storage applications. PMID:19690734

  16. Anti-Obesity Effects of Starter Fermented Kimchi on 3T3-L1 Adipocytes

    PubMed Central

    Lee, Kyung-Hee; Song, Jia-Le; Park, Eui-Seong; Ju, Jaehyun; Kim, Hee-Young; Park, Kun-Young

    2015-01-01

    The anti-obesity effects of starter (Leuconostoc mesenteroides+Lactobacillus plantarum) fermented kimchi on 3T3-L1 adipocyte were studied using naturally fermented kimchi (NK), a functional kimchi (FK, NK supplemented with green tea), and FK supplemented with added starters (FKS). Oil red O staining and cellular levels of triglyceride (TG) and glycerol were used to evaluate the in vitro anti-obesity effects of these kimchis in 3T3-L1 cells. The expressions of adipogenesis/lipogenesis-related genes of peroxisome proliferator-active receptor (PPAR)-γ, CCAAT/enhance-binding protein (C/EBP)-α, and fatty acid synthase (FAS) were determined by RT-PCR. Kimchis, especially FKS, markedly decreased TG levels and increased levels of intracellular glycerol and lipid lipolysis. In addition, FKS also reduced the mRNA levels of PPAR-γ, C/EBP-α, and FAS, which are related to adipogenesis/lipogenesis in 3T3-L1 cells. These results suggest the anti-obesity effects of FKS were to due to enhanced lipolysis and reduced adipogenesis/lipogenesis in 3T3-L1 adipocytes. PMID:26770918

  17. Fluorescence lifetime imaging of lipids during 3T3-L1 cell differentiation

    NASA Astrophysics Data System (ADS)

    Song, Young Sik; Won, Young Jae; Lee, Sang-Hak; Kim, Dug Young

    2014-03-01

    Obesity is becoming a big health problem in these days. Since increased body weight is due to increased number and size of the triglyceride-storing adipocytes, many researchers are working on differentiation conditions and processes of adipocytes. Adipocytes also work as regulators of whole-body energy homeostasis by secreting several proteins that regulate processes as diverse as haemostasis, blood pressure, immune function, angiogenesis and energy balance. 3T3-L1 cells are widely used cell line for studying adipogenesis because it can differentiate into an adipocyte-like phenotype under appropriate conditions. In this paper, we propose an effective fluorescence lifetime imaging technique which can easily distinguish lipids in membrane and those in lipid droplets. Nile red dyes are attached to lipids in 3T3-L1 cells. Fluorescence lifetime images were taken for 2 week during differentiation procedure of 3T3-L1 cells into adipocytes. We used 488 nm pulsed laser with 5MHz repetition rate and emission wavelength is 520 nm of Nile Red fluorescent dye. Results clearly show that the lifetime of Nile red in lipid droplets are smaller than those in cell membrane. Our results suggest that fluorescence lifetime imaging can be a very powerful tool to monitor lipid droplet formation in adipocytes from 3T3-L1 cells.

  18. The effect of 3 T MRI on microleakage of amalgam restorations

    PubMed Central

    Yilmaz, S; Misirlioğlu, M

    2013-01-01

    Objectives: To evaluate the effects of 3 T magnetic field on microleakage of amalgam restorations containing three different types of silver (Ag). Methods: 60 extracted teeth were restored with three different types of amalgam filling materials. Restored teeth were sectioned mesiodistally and divided into experimental and control groups. Experimental groups were exposed to a magnetic field of 3 T for 20 min. All samples were plunged into 2% basic fuchsin solution and examined under a digital microscope by three different observers with regard to microleakage. Results: Statistical analysis showed significant differences in microleakage between the groups exposed to MRI and controls, whereas differences in microleakage between amalgam types were insignificant. Conclusions: The primary risk of MRI systems arises from the effects of its strong magnetic field on objects containing ferromagnetic materials. An MRI of 1.5 T is known to be safe for amalgam restorations. However, our research indicates that MRI is not completely devoid of any effects on amalgam restorations. PMID:23674614

  19. Electron distribution function and recombination coefficient in ultracold plasma in a magnetic field

    SciTech Connect

    Bobrov, A. A.; Bronin, S. Ya.; Zelener, B. B.; Zelener, B. V.; Manykin, E. A.; Khikhlukha, D. R.

    2013-07-15

    The electron distribution function and diffusion coefficient in energy space have been calculated for the first time for a weakly coupled ultracold plasma in a magnetic field in the range of magnetic fields B = 100-50000 G for various temperatures. The dependence of these characteristics on the magnetic field is analyzed and the distribution function is shown to depend on the electron energy shift in a magnetic field. The position of the 'bottleneck' of the distribution function has been found to be shifted toward negative energies with increasing magnetic field. The electron velocity autocorrelators as a function of the magnetic field have been calculated; their behavior suggests that the frequency of collisions between charged particles decreases significantly with increasing magnetic field. The collisional recombination coefficient {alpha}{sub B} has been calculated in the diffusion approximation for a weakly coupled ultracold plasma in a magnetic field. An increase in magnetic field is shown to lead to a decrease in {alpha}{sub B} and this decrease can be several orders of magnitude.

  20. Expression of Nanog gene promotes NIH3T3 cell proliferation

    SciTech Connect

    Zhang Jingyu; Wang Xia; Chen Bing; Suo Guangli; Zhao Yanhong; Duan Ziyuan; Dai Jianwu . E-mail: jwdai@genetics.ac.cn

    2005-12-16

    Cells are the functional elements in tissue engineering and regenerative medicine. A large number of cells are usually needed for these purposes. However, there are numbers of limitations for in vitro cell proliferation. Nanog is an important self-renewal determinant in embryonic stem cells. However, it remains unknown whether Nanog will influence the cell cycle and cell proliferation of mature cells. In this study, we expressed Nanog in NIH3T3 cells and showed that expression of Nanog in NIH3T3 promoted cells to enter into S phase and enhanced cell proliferation. This suggests that Nanog gene might function in a similar fashion in mature cells as in ES cells. In addition, it may provide an approach for in vitro cell expansion.

  1. Human papillomavirus type 16 DNA-induced malignant transformation of NIH 3T3 cells

    SciTech Connect

    Yasumoto, S.; Burkhardt, A.L.; Doniger, J.; DiPaolo, J.A.

    1986-02-01

    A biological function for human papillomavirus 16 (HPV 16) DNA was demonstrated by transformation of NIH 3T3 cells. HPV 16 DNA has been found frequently in genital cancer and has been classified as a papillomavirus on the basis of DNA homology. A recombinant HPV 16 DNA (pSHPV16d), which contains a head-to-tail dimer of the full-length HPV 16 genome, induced morphologic transformation; the transformed cells were tumorigenic in nude mice. Expression of transforming activity was unique because of the long latency period (more than 4 weeks) required for induction of morphologic transformation and because the transfected DNA existed primarily in a multimeric form with some rearrangement. Furthermore, virus-specific RNAs were expressed in the transformants. The transformation of NIH 3T3 cells provides a model for analyzing the functions of HPV 16, which is associated with cervical carcinomas.

  2. Activity of glucose oxidase functionalized onto magnetic nanoparticles

    PubMed Central

    Kouassi, Gilles K; Irudayaraj, Joseph; McCarty, Gregory

    2005-01-01

    Background Magnetic nanoparticles have been significantly used for coupling with biomolecules, due to their unique properties. Methods Magnetic nanoparticles were synthesized by thermal co-precipitation of ferric and ferrous chloride using two different base solutions. Glucose oxidase was bound to the particles by direct attachment via carbodiimide activation or by thiophene acetylation of magnetic nanoparticles. Transmission electron microscopy was used to characterize the size and structure of the particles while the binding of glucose oxidase to the particles was confirmed using Fourier transform infrared spectroscopy. Results The direct binding of glucose oxidase via carbodiimide activity was found to be more effective, resulting in bound enzyme efficiencies between 94–100% while thiophene acetylation was 66–72% efficient. Kinetic and stability studies showed that the enzyme activity was more preserved upon binding onto the nanoparticles when subjected to thermal and various pH conditions. The overall activity of glucose oxidase was improved when bound to magnetic nanoparticles Conclusion Binding of enzyme onto magnetic nanoparticles via carbodiimide activation is a very efficient method for developing bioconjugates for biological applications PMID:15762994

  3. Fat-suppression techniques for 3-T MR imaging of the musculoskeletal system.

    PubMed

    Del Grande, Filippo; Santini, Francesco; Herzka, Daniel A; Aro, Michael R; Dean, Cooper W; Gold, Garry E; Carrino, John A

    2014-01-01

    Fat suppression is an important technique in musculoskeletal imaging to improve the visibility of bone-marrow lesions; evaluate fat in soft-tissue masses; optimize the contrast-to-noise ratio in magnetic resonance (MR) arthrography; better define lesions after administration of contrast material; and avoid chemical shift artifacts, primarily at 3-T MR imaging. High-field-strength (eg, 3-T) MR imaging has specific technical characteristics compared with lower-field-strength MR imaging that influence the use and outcome of various fat-suppression techniques. The most commonly used fat-suppression techniques for musculoskeletal 3-T MR imaging include chemical shift (spectral) selective (CHESS) fat saturation, inversion recovery pulse sequences (eg, short inversion time inversion recovery [STIR]), hybrid pulse sequences with spectral and inversion-recovery (eg, spectral adiabatic inversion recovery and spectral attenuated inversion recovery [SPAIR]), spatial-spectral pulse sequences (ie, water excitation), and the Dixon techniques. Understanding the different fat-suppression options allows radiologists to adopt the most appropriate technique for their clinical practice. PMID:24428292

  4. Fat-Suppression Techniques for 3-T MR Imaging of the Musculoskeletal System1

    PubMed Central

    Del Grande, Filippo; Santini, Francesco; Herzka, Daniel A.; Aro, Michael R.; Dean, Cooper W.; Gold, Garry E.; Carrino, John A.

    2015-01-01

    Fat suppression is an important technique in musculoskeletal imaging to improve the visibility of bone-marrow lesions; evaluate fat in soft-tissue masses; optimize the contrast-to-noise ratio in magnetic resonance (MR) arthrography; better define lesions after administration of contrast material; and avoid chemical shift artifacts, primarily at 3-T MR imaging. High-field-strength (eg, 3-T) MR imaging has specific technical characteristics compared with lower-field-strength MR imaging that influence the use and outcome of various fat-suppression techniques. The most commonly used fat-suppression techniques for musculoskeletal 3-T MR imaging include chemical shift (spectral) selective (CHESS) fat saturation, inversion recovery pulse sequences (eg, short inversion time inversion recovery [STIR]), hybrid pulse sequences with spectral and inversion-recovery (eg, spectral adiabatic inversion recovery and spectral attenuated inversion recovery [SPAIR]), spatial-spectral pulse sequences (ie, water excitation), and the Dixon techniques. Understanding the different fat-suppression options allows radiologists to adopt the most appropriate technique for their clinical practice. PMID:24428292

  5. Coronary artery anomalies and variants: technical feasibility of assessment with coronary MR angiography at 3 T.

    PubMed

    Gharib, Ahmed M; Ho, Vincent B; Rosing, Douglas R; Herzka, Daniel A; Stuber, Matthias; Arai, Andrew E; Pettigrew, Roderic I

    2008-04-01

    The purpose of this study was to prospectively use a whole-heart three-dimensional (3D) coronary magnetic resonance (MR) angiography technique specifically adapted for use at 3 T and a parallel imaging technique (sensitivity encoding) to evaluate coronary arterial anomalies and variants (CAAV). This HIPAA-compliant study was approved by the local institutional review board, and informed consent was obtained from all participants. Twenty-two participants (11 men, 11 women; age range, 18-62 years) were included. Ten participants were healthy volunteers, whereas 12 participants were patients suspected of having CAAV. Coronary MR angiography was performed with a 3-T MR imager. A 3D free-breathing navigator-gated and vector electrocardiographically-gated segmented k-space gradient-echo sequence with adiabatic T2 preparation pulse and parallel imaging (sensitivity encoding) was used. Whole-heart acquisitions (repetition time msec/echo time msec, 4/1.35; 20 degrees flip angle; 1 x 1 x 2-mm acquired voxel size) lasted 10-12 minutes. Mean examination time was 41 minutes +/- 14 (standard deviation). Findings included aneurysms, ectasia, arteriovenous fistulas, and anomalous origins. The 3D whole-heart acquisitions developed for use with 3 T are feasible for use in the assessment of CAAV. PMID:18372470

  6. Functionalization and magnetization of carbon nanotubes using Co-60 gamma-ray irradiation

    NASA Astrophysics Data System (ADS)

    Chen, C. Y.; Fu, M. J.; Tsai, C. Y.; Lin, F. H.; Chen, K. Y.

    2014-10-01

    Functionalized magnetic carbon nanotubes (CNTs) can be used in the biological and biomedical fields as biosensors, drug delivery systems, etc., which makes research into processes for manufacturing modified CNTs quite important. In this paper, Co-60 gamma irradiation is shown to be an effective tool for fabricating functionalized and magnetized CNTs. After the Co-60 gamma irradiation, the presence of carboxylic functional groups on the CNT walls was confirmed by their Fourier transform infrared spectra, and the presence of Fe3O4 was verified by the X-ray diffraction patterns. The functionalized and magnetized CNTs produced using Co-60 gamma irradiation have excellent dispersion properties. The techniques for functionalizing and magnetizing CNTs are introduced in this paper, and applications of the modified CNTs will be reported after more data are gathered.

  7. Force-free magnetic fields - Generating functions and footpoint displacements

    NASA Technical Reports Server (NTRS)

    Wolfson, Richard; Verma, Ritu

    1991-01-01

    This paper presents analytic and numerical calculations that explore equilibrium sequences of bipolar force-free magnetic fields in relation to displacments of their magnetic footpoints. It is shown that the appearance of magnetic islands - sometimes interpreted as marking the loss of equilibrium in models of the solar atmosphere - is likely associated only with physically unrealistic footpoint displacements such as infinite separation or 'tearing' of the model photosphere. The work suggests that the loss of equilibrium in bipolar configurations, sometimes proposed as a mechanism for eruptive solar events, probably requires either fully three-dimensional field configurations or nonzero plasma pressure. The results apply only to fields that are strictly bipolar, and do not rule out equilibrium loss in more complex structures such as quadrupolar fields.

  8. CLOCK promotes 3T3-L1 cell proliferation via Wnt signaling.

    PubMed

    Zhu, Zhu; Hua, Bingxuan; Xu, Lirong; Yuan, Gongsheng; Li, Ermin; Li, Xiaobo; Sun, Ning; Yan, Zuoqin; Lu, Chao; Qian, Ruizhe

    2016-07-01

    Circadian genes control most of the physiological functions including cell cycle. Cell proliferation is a critical factor in the differentiation of progenitor cells. However, the role of Clock gene in the regulation of cell cycle via wingless-type (Wnt) pathway and the relationship between Clock and adipogenesis are unclear. We found that the circadian locomotor output cycles kaput (Clock) regulated the proliferation and the adipogenesis of 3T3-L1 preadipocytes. We found that Clock attenuation inhibited the viability of 3T3-L1 preadipocytes in the cell counting kit 8. The expression of c-Myc and Cyclin D1 decreased dramatically in 3T3-L1 when Clock was silenced with short interfering RNA and was also decreased in fat tissue and adipose tissue-derived stem cells of Clock(Δ19) mice. Clock directly controls the expression of the components of Wnt signal transduction pathway, which was verified by serum shock, chromatin immunoprecipitation, Western blot, and quantitative real-time polymerase chain reaction (qRT-PCR). Furthermore, IWR-1, a Wnt signal pathway inhibitor, inhibited the cell cycle promotion by CLOCK, which was detected by cell viability assay, flow cytometry, and qRT-PCR. Therefore, CLOCK transcription control of Wnt signaling promotes cell cycle progression in 3T3-L1 preadipocytes. Clock inhibited the adipogenesis on day 2 in 3T3-L1 cells via Oil Red O staining and qRT-PCR detection and probably related to cellular differentiation. These data provide evidence that the circadian gene Clock regulates the proliferation of preadipocytes and affects adipogenesis. © 2016 IUBMB Life, 68(7):557-568, 2016. PMID:27194636

  9. Effect of magnetic field on dynamic response function in Ising systems

    NASA Astrophysics Data System (ADS)

    Pawlak, A.; Erdem, R.

    2013-11-01

    As a continuation of our previously published work, we use the Nelson's method to study the effect of the magnetic field on the temperature-, frequency-, and momentum-dependent response function and dynamic correlation function in the Ising-type systems with relaxational dynamics. The scaling function is given within the renormalization group formalism at one-loop order for nonzero field. We show how the typical two-peak structure of the real part of response function changes with magnetic field. We discuss the deviations of the correlation function from the Gaussian expression. The Fisher-Langer maximum is also considered.

  10. The continuum intensity as a function of magnetic field. II. Local magnetic flux and convective flows

    NASA Astrophysics Data System (ADS)

    Kobel, P.; Solanki, S. K.; Borrero, J. M.

    2012-06-01

    Context. To deepen our understanding of the role of small-scale magnetic fields in active regions (ARs) and in the quiet Sun (QS) on the solar irradiance, it is fundamental to investigate the physical processes underlying their continuum brightness. Previous results showed that magnetic elements in the QS reach larger continuum intensities than in ARs at disk center, but left this difference unexplained. Aims: We use Hinode/SP disk center data to study the influence of the local amount of magnetic flux on the vigour of the convective flows and the continuum intensity contrasts. Methods: The apparent (i.e. averaged over a pixel) longitudinal field strength and line-of-sight (LOS) plasma velocity were retrieved by means of Milne-Eddington inversions (VFISV code). We analyzed a series of boxes taken over AR plages and the QS, to determine how the continuum intensity contrast of magnetic elements, the amplitude of the vertical flows and the box-averaged contrast were affected by the mean longitudinal field strength in the box (which scales with the total unsigned flux in the box). Results: Both the continuum brightness of the magnetic elements and the dispersion of the LOS velocities anti-correlate with the mean longitudinal field strength. This can be attributed to the "magnetic patches" (here defined as areas where the longitudinal field strength is above 100 G) carrying most of the flux in the boxes. There the velocity amplitude and the spatial scale of convection are reduced. Due to this hampered convective transport, these patches appear darker than their surroundings. Consequently, the average brightness of a box decreases as the the patches occupy a larger fraction of it and the amount of embedded flux thereby increases. Conclusions: Our results suggest that as the magnetic flux increases locally (e.g. from weak network to strong plage), the heating of the magnetic elements is reduced by the intermediate of a more suppressed convective energy transport within

  11. Irregular wave functions of a hydrogen atom in a uniform magnetic field

    NASA Technical Reports Server (NTRS)

    Wintgen, D.; Hoenig, A.

    1989-01-01

    The highly excited irregular wave functions of a hydrogen atom in a uniform magnetic field are investigated analytically, with wave function scarring by periodic orbits considered quantitatively. The results obtained confirm that the contributions of closed classical orbits to the spatial wave functions vanish in the semiclassical limit. Their disappearance, however, is slow. This discussion is illustrated by numerical examples.

  12. Rapid eye movement-related brain activation in human sleep: a functional magnetic resonance imaging study.

    PubMed

    Wehrle, Renate; Czisch, Michael; Kaufmann, Christian; Wetter, Thomas C; Holsboer, Florian; Auer, Dorothee P; Pollmächer, Thomas

    2005-05-31

    In animal models, ponto-geniculo-occipital waves appear as an early sign of rapid eye movement sleep and may be functionally significant for brain plasticity processes. In this pilot study, we use a combined polysomnographic and functional magnetic resonance imaging approach, and show distinct magnetic resonance imaging signal increases in the posterior thalamus and occipital cortex in close temporal relationship to rapid eye movements during human rapid eye movement sleep. These findings are consistent with cell recordings in animal experiments and demonstrate that functional magnetic resonance imaging can be utilized to detect ponto-geniculo-occipital-like activity in humans. Studying intact neuronal networks underlying sleep regulation is no longer confined to animal models, but has been shown to be feasible in humans by a combined functional magnetic resonance imaging and electroencephalograph approach. PMID:15891584

  13. Brain functional magnetic resonance imaging response to glucose and fructose infusions in humans

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Objective: In animals, intracerebroventricular glucose and fructose have opposing effects on appetite and weight regulation. In humans, functional brain magnetic resonance imaging (fMRI) studies during carbohydrate ingestion suggest that glucose may regulate HT signaling but are potentially confoun...

  14. Distinctions between manipulation and function knowledge of objects: evidence from functional magnetic resonance imaging.

    PubMed

    Boronat, Consuelo B; Buxbaum, Laurel J; Coslett, H Branch; Tang, Kathy; Saffran, Eleanor M; Kimberg, Daniel Y; Detre, John A

    2005-05-01

    A prominent account of conceptual knowledge proposes that information is distributed over visual, tactile, auditory, motor and verbal-declarative attribute domains to the degree to which these features were activated when the knowledge was acquired [D.A. Allport, Distributed memory, modular subsystems and dysphagia, In: S.K. Newman, R. Epstein (Eds.), Current perspectives in dysphagia, Churchill Livingstone, Edinburgh, 1985, pp. 32-60]. A corollary is that when drawing upon this knowledge (e.g., to answer questions), particular aspects of this distributed information is re-activated as a function of the requirements of the task at hand [L.J. Buxbaum, E.M. Saffran, Knowledge of object manipulation and object function: dissociations in apraxic and non-apraxic subjects. Brain and Language, 82 (2002) 179-199; L.J. Buxbaum, T. Veramonti, M.F. Schwartz, Function and manipulation tool knowledge in apraxia: knowing 'what for' but not 'how', Neurocase, 6 (2000) 83-97; W. Simmons, L. Barsalou, The similarity-in-topography principle: Reconciling theories of conceptual deficits, Cognitive Neuropsychology, 20 (2003) 451-486]. This account predicts that answering questions about object manipulation should activate brain regions previously identified as components of the distributed sensory-motor system involved in object use, whereas answering questions about object function (that is, the purpose that it serves) should activate regions identified as components of the systems supporting verbal-declarative features. These predictions were tested in a functional magnetic resonance imaging (fMRI) study in which 15 participants viewed picture or word pairs denoting manipulable objects and determined whether the objects are manipulated similarly (M condition) or serve the same function (F condition). Significantly greater and more extensive activations in the left inferior parietal lobe bordering the intraparietal sulcus were seen in the M condition with pictures and, to a lesser

  15. QUANTITATIVE PLANAR AND VOLUMETRIC CARDIAC MEASUREMENTS USING 64 MDCT AND 3T MRI VS. STANDARD 2D AND M-MODE ECHOCARDIOGRAPHY: DOES ANESTHETIC PROTOCOL MATTER?

    PubMed

    Drees, Randi; Johnson, Rebecca A; Stepien, Rebecca L; Munoz Del Rio, Alejandro; Saunders, Jimmy H; François, Christopher J

    2015-01-01

    Cross-sectional imaging of the heart utilizing computed tomography and magnetic resonance imaging (MRI) has been shown to be superior for the evaluation of cardiac morphology and systolic function in humans compared to echocardiography. The purpose of this prospective study was to test the effects of two different anesthetic protocols on cardiac measurements in 10 healthy beagle dogs using 64-multidetector row computed tomographic angiography (64-MDCTA), 3T magnetic resonance (MRI) and standard awake echocardiography. Both anesthetic protocols used propofol for induction and isoflourane for anesthetic maintenance. In addition, protocol A used midazolam/fentanyl and protocol B used dexmedetomedine as premedication and constant rate infusion during the procedure. Significant elevations in systolic and mean blood pressure were present when using protocol B. There was overall good agreement between the variables of cardiac size and systolic function generated from the MDCTA and MRI exams and no significant difference was found when comparing the variables acquired using either anesthetic protocol within each modality. Systolic function variables generated using 64-MDCTA and 3T MRI were only able to predict the left ventricular end diastolic volume as measured during awake echocardiogram when using protocol B and 64-MDCTA. For all other systolic function variables, prediction of awake echocardiographic results was not possible (P = 1). Planar variables acquired using MDCTA or MRI did not allow prediction of the corresponding measurements generated using echocardiography in the awake patients (P = 1). Future studies are needed to validate this approach in a more varied population and clinically affected dogs. PMID:26082285

  16. Quantitative planar and volumetric cardiac measurements using 64 MDCT and 3T MRI versus standard 2D and M-mode echocardiography: Does anesthetic protocol matter?

    PubMed Central

    Drees, Randi; Johnson, Rebecca A; Stepien, Rebecca L; Rio, Alejandro Munoz Del; Saunders, Jimmy H; François, Christopher J

    2016-01-01

    Cross-sectional imaging of the heart utilizing computed tomography (CT) and magnetic resonance imaging (MRI) has been shown to be superior for the evaluation of cardiac morphology and systolic function in humans compared to echocardiography. The purpose of this prospective study was to test the effects of two different anesthetic protocols on cardiac measurements in 10 healthy beagle dogs using 64-multidetector row computed tomographic angiography (64-MDCTA), 3T magnetic resonance (MRI) and standard awake echocardiography. Both anesthetic protocols used propofol for induction and isoflourane for anesthetic maintenance. In addition, protocol A used midazolam/fentanyl and protocol B used dexmedetomedine as premedication and constant rate infusion during the procedure. Significant elevations in systolic and mean blood pressure were present when using protocol B. There was overall good agreement between the variables of cardiac size and systolic function generated from the MDCTA and MRI exams and no significant difference was found when comparing the variables acquired using either anesthetic protocol within each modality. Systolic function variables generated using 64-MDCTA and 3T MRI were only able to predict the left ventricular end diastolic volume as measured during awake echocardiogram when using protocol B and 64-MDCTA. For all other systolic function variables, prediction of awake echocardiographic results was not possible (P = 1). Planar variables acquired using MDCTA or MRI did not allow prediction of the corresponding measurements generated using echocardiography in the awake patients (P=1). Future studies are needed to validate this approach in a more varied population and clinically affected dogs. PMID:26082285

  17. Hyperpolarized Magnetic Resonance as a Sensitive Detector of Metabolic Function

    PubMed Central

    2015-01-01

    Hyperpolarized magnetic resonance allows for noninvasive measurements of biochemical reactions in vivo. Although this technique provides a unique tool for assaying enzymatic activities in intact organs, the scope of its application is still elusive for the wider scientific community. The purpose of this review is to provide key principles and parameters to guide the researcher interested in adopting this technology to address a biochemical, biomedical, or medical issue. It is presented in the form of a compendium containing the underlying essential physical concepts as well as suggestions to help assess the potential of the technique within the framework of specific research environments. Explicit examples are used to illustrate the power as well as the limitations of hyperpolarized magnetic resonance. PMID:25369537

  18. Magnetic resonance imaging and electromyography as indexes of muscle function

    NASA Technical Reports Server (NTRS)

    Adams, Gregory R.; Duvoisin, Marc R.; Dudley, Gary A.

    1992-01-01

    A hypothesis is tested that exercise-induced magnetic resonance (MR) contrast shifts would relate to electromyography (EMG) amplitude if both measures reflect muscle use during exercise. Both magnetic resonance images (MRI) and EMG data were obtained for separate eccentric (ECC) and cocentric (CON) exercise of increasing intensity for seven subjects 30-32 yr old. CON and ECC actions caused increased integrated EMG (IEMG) and T2 values which were strongly related with relative resistance. The rate of increase and absolute value of both T2 and IEMG were found to be greater for CON than for ECC actions. For both actions IEMG and T2 were correlated. Data obtained suggest that surface IEMG accurately reflects the contractile behavior of muscle and exercise-induced increases in MRI T2 values reflect certain processes that scale with muscle use.

  19. 3-T MRI detects inflammatory stenosis of the vertebral artery in giant cell arteritis.

    PubMed

    Geiger, J; Uhl, M; Peter, H H; Langer, M; Bley, T A

    2008-05-01

    Giant cell arteritis (GCA) is a granulomatous vasculitis. Early diagnosis is important for the initiation of corticosteroid treatment because the arteritis can result in blindness. In most of the cases, the superficial cranial arteries are affected. However, extracranial involvement of various arteries is known. Here, we report a case of histologically proven GCA with an inflammatory stenosis of the right vertebral artery. For complete evaluation of the extension of the disease, an optimized protocol of high-resolution magnetic resonance imaging at 3 T in combination with contrast-enhanced magnetic resonance angiography was performed. This non-invasive method facilitates the differentiation of inflamed and healthy segments of small cranial arteries, may help to find appropriate sites for biopsy, and allows the assessment of affected extracranial vessels. In this patient case, even the cause of vertebral stenosis--inflammatory versus arteriosclerotic--could be elucidated. PMID:18172573

  20. True Pathologic Abnormality versus Artifact Foot Position and Magic Angle Artifact in the Peroneal Tendons with 3T Imaging.

    PubMed

    Horn, Deena B; Meyers, Steven; Astor, William

    2015-09-01

    Magnetic resonance imaging is a commonly ordered examination by many foot and ankle surgeons for ankle pain and suspected peroneal tendon pathologic abnormalities. Magic angle artifact is one of the complexities associated with this imaging modality. Magic angle refers to the increased signal on magnetic resonance images associated with the highly organized collagen fibers in tendons and ligaments when they are orientated at a 55° angle to the main magnetic field. We present several examples from a clinical practice setting using 3T imaging illustrating a substantial reduction in magic angle artifact of the peroneal tendon in the prone plantarflexed position compared with the standard neutral (right angle) position. PMID:26429616

  1. Small-angle neutron scattering correlation functions of bulk magnetic materials

    PubMed Central

    Mettus, Denis; Michels, Andreas

    2015-01-01

    On the basis of the continuum theory of micromagnetics, the correlation function of the spin-misalignment small-angle neutron scattering cross section of bulk ferromagnets (e.g. elemental polycrystalline ferromagnets, soft and hard magnetic nanocomposites, nanoporous ferromagnets, or magnetic steels) is computed. For such materials, the spin disorder which is related to spatial variations in the saturation magnetization and magnetic anisotropy field results in strong spin-misalignment scattering dΣM/dΩ along the forward direction. When the applied magnetic field is perpendicular to the incoming neutron beam, the characteristics of dΣM/dΩ (e.g. the angular anisotropy on a two-dimensional detector or the asymptotic power-law exponent) are determined by the ratio of magnetic anisotropy field strength H p to the jump ΔM in the saturation magnetization at internal interfaces. Here, the corresponding one- and two-dimensional real-space correlations are analyzed as a function of applied magnetic field, the ratio H p/ΔM, the single-particle form factor and the particle volume fraction. Finally, the theoretical results for the correlation function are compared with experimental data on nanocrystalline cobalt and nickel. PMID:26500464

  2. General protocol for the synthesis of functionalized magnetic nanoparticles for magnetic resonance imaging from protected metal-organic precursors.

    PubMed

    Hu, He; Zhang, Chongkun; An, Lu; Yu, Yanrong; Yang, Hong; Sun, Jin; Wu, Huixia; Yang, Shiping

    2014-06-01

    The development of magnetic nanoparticles (MNPs) with functional groups has been intensively pursued in recent years. Herein, a simple, versatile, and cost-effective strategy to synthesize water-soluble and amino-functionalized MNPs, based on the thermal decomposition of phthalimide-protected metal-organic precursors followed by deprotection, was developed. The resulting amino-functionalized Fe3O4, MnFe2O4, and Mn3O4 MNPs with particle sizes of about 14.3, 7.5, and 6.6 nm, respectively, had narrow size distributions and good dispersibility in water. These MNPs also exhibited high magnetism and relaxivities of r2 = 107.25 mM(-1)  s(-1) for Fe3O4, r2 = 245.75 mM(-1)  s(-1) for MnFe2O4, and r1 = 2.74 mM(-1)  s(-1) for Mn3O4. The amino-functionalized MNPs were further conjugated with a fluorescent dye (rhodamine B) and a targeting ligand (folic acid: FA) and used as multifunctional probes. Magnetic resonance imaging and flow-cytometric studies showed that these probes could specifically target cancer cells overexpressing FA receptors. This new protocol opens a new way for the synthesis and design of water-soluble and amino-functionalized MNPs by an easy and versatile route. PMID:24771671

  3. Single step synthesis, characterization and applications of curcumin functionalized iron oxide magnetic nanoparticles.

    PubMed

    Bhandari, Rohit; Gupta, Prachi; Dziubla, Thomas; Hilt, J Zach

    2016-10-01

    Magnetic iron oxide nanoparticles have been well known for their applications in magnetic resonance imaging (MRI), hyperthermia, targeted drug delivery, etc. The surface modification of these magnetic nanoparticles has been explored extensively to achieve functionalized materials with potential application in biomedical, environmental and catalysis field. Herein, we report a novel and versatile single step methodology for developing curcumin functionalized magnetic Fe3O4 nanoparticles without any additional linkers, using a simple coprecipitation technique. The magnetic nanoparticles (MNPs) were characterized using transmission electron microscopy, X-ray diffraction, fourier transform infrared spectroscopy and thermogravimetric analysis. The developed MNPs were employed in a cellular application for protection against an inflammatory agent, a polychlorinated biphenyl (PCB) molecule. PMID:27287099

  4. Phonon and magnetic structure in δ-plutonium from density-functional theory

    PubMed Central

    Söderlind, Per; Zhou, F.; Landa, A.; Klepeis, J. E.

    2015-01-01

    We present phonon properties of plutonium metal obtained from a combination of density-functional-theory (DFT) electronic structure and the recently developed compressive sensing lattice dynamics (CSLD). The CSLD model is here trained on DFT total energies of several hundreds of quasi-random atomic configurations for best possible accuracy of the phonon properties. The calculated phonon dispersions compare better with experiment than earlier results obtained from dynamical mean-field theory. The density-functional model of the electronic structure consists of disordered magnetic moments with all relativistic effects and explicit orbital-orbital correlations. The magnetic disorder is approximated in two ways: (i) a special quasi-random structure and (ii) the disordered-local-moment method within the coherent potential approximation. Magnetism in plutonium has been debated intensely, but the present magnetic approach for plutonium is validated by the close agreement between the predicted magnetic form factor and that of recent neutron-scattering experiments. PMID:26514238

  5. Phonon and magnetic structure in δ-plutonium from density-functional theory

    SciTech Connect

    Söderlind, Per; Zhou, F.; Landa, A.; Klepeis, J. E.

    2015-10-30

    We present phonon properties of plutonium metal obtained from a combination of density-functional-theory (DFT) electronic structure and the recently developed compressive sensing lattice dynamics (CSLD). The CSLD model is here trained on DFT total energies of several hundreds of quasi-random atomic configurations for best possible accuracy of the phonon properties. The calculated phonon dispersions compare better with experiment than earlier results obtained from dynamical mean-field theory. The density-functional model of the electronic structure consists of disordered magnetic moments with all relativistic effects and explicit orbital-orbital correlations. The magnetic disorder is approximated in two ways: (i) a special quasi-random structure and (ii) the disordered-local-moment (DLM) method within the coherent potential approximation. Magnetism in plutonium has been debated intensely, However, the present magnetic approach for plutonium is validated by the close agreement between the predicted magnetic form factor and that of recent neutron-scattering experiments.

  6. Phonon and magnetic structure in δ-plutonium from density-functional theory.

    PubMed

    Söderlind, Per; Zhou, F; Landa, A; Klepeis, J E

    2015-01-01

    We present phonon properties of plutonium metal obtained from a combination of density-functional-theory (DFT) electronic structure and the recently developed compressive sensing lattice dynamics (CSLD). The CSLD model is here trained on DFT total energies of several hundreds of quasi-random atomic configurations for best possible accuracy of the phonon properties. The calculated phonon dispersions compare better with experiment than earlier results obtained from dynamical mean-field theory. The density-functional model of the electronic structure consists of disordered magnetic moments with all relativistic effects and explicit orbital-orbital correlations. The magnetic disorder is approximated in two ways: (i) a special quasi-random structure and (ii) the disordered-local-moment method within the coherent potential approximation. Magnetism in plutonium has been debated intensely, but the present magnetic approach for plutonium is validated by the close agreement between the predicted magnetic form factor and that of recent neutron-scattering experiments. PMID:26514238

  7. Magnetic assembly of transparent and conducting graphene-based functional composites

    NASA Astrophysics Data System (ADS)

    Le Ferrand, Hortense; Bolisetty, Sreenath; Demirörs, Ahmet F.; Libanori, Rafael; Studart, André R.; Mezzenga, Raffaele

    2016-06-01

    Innovative methods producing transparent and flexible electrodes are highly sought in modern optoelectronic applications to replace metal oxides, but available solutions suffer from drawbacks such as brittleness, unaffordability and inadequate processability. Here we propose a general, simple strategy to produce hierarchical composites of functionalized graphene in polymeric matrices, exhibiting transparency and electron conductivity. These are obtained through protein-assisted functionalization of graphene with magnetic nanoparticles, followed by magnetic-directed assembly of the graphene within polymeric matrices undergoing sol-gel transitions. By applying rotating magnetic fields or magnetic moulds, both graphene orientation and distribution can be controlled within the composite. Importantly, by using magnetic virtual moulds of predefined meshes, graphene assembly is directed into double-percolating networks, reducing the percolation threshold and enabling combined optical transparency and electrical conductivity not accessible in single-network materials. The resulting composites open new possibilities on the quest of transparent electrodes for photovoltaics, organic light-emitting diodes and stretchable optoelectronic devices.

  8. Synthesis and design of functionalized magnetic nanocolloids for water pollution remediation

    NASA Astrophysics Data System (ADS)

    Campos, A. F. C.; Ferreira, M. A.; Marinho, E. P.; Tourinho, F. A.; Depeyrot, J.

    This work focus on the potential applications of magnetic nanoparticles on pollution remediation. We draw attention to the chemical design of functionalized magnetic colloids based on tartrate ligands to be used in magnetic separation of heavy metals from wastewater. Coupling the speciation diagrams of nanoferrites particles surface with that of the tartaric acid, it was possible to provide a theoretical prediction of the optimal pH for particle surface-ligand complexation. Finally, from an electrochemical approach based on simultaneous potentiometric and conductimetric titrations it was possible to determine the saturation value of the surface charge density of the functionalized nanoparticles and its pH dependence.

  9. An investigation of the value of spin-echo-based fMRI using a Stroop color-word matching task and EPI at 3 T.

    PubMed

    Norris, David G; Zysset, Stefan; Mildner, Toralf; Wiggins, Christopher J

    2002-03-01

    This study examines the value of spin-echo-based fMRI for cognitive studies at the main magnetic field strength of 3 T using a spin-echo EPI (SE-EPI) sequence and a Stroop color-word matching task. SE-EPI has the potential advantage over conventional gradient-echo EPI (GE-EPI) that signal losses caused by dephasing through the slice are not present, and hence although image distortion will be the same as for an equivalent GE-EPI sequence, signal voids will be eliminated. The functional contrast in SE-EPI will be lower than for GE-EPI, as static dephasing effects do not contribute. As an auxiliary experiment interleaved diffusion-weighted and non-diffusion-weighted SE-EPI was performed in the visual cortex to further elucidate the mechanims of functional contrast. In the Stroop experiment activation was detected in all areas previously found using GE-EPI. Additional frontopolar and ventral frontomedian activations were also found, which could not be detected using GE-EPI. The experiments from visual cortex indicated that at 3 T the BOLD signal change has contributions from the extravascular space and larger blood vessels in roughly equal amounts. In comparison with GE-EPI the absence of static dephasing effects would seem to result in a superior intrinsic spatial resolution. In conclusion the sensitivity of SE-EPI at 3 T is sufficient to make it the method of choice for fMR studies that require a high degree of spatial localization or where the requirement is to detect activation in regions affected by strong susceptibility gradients. PMID:11848715

  10. Large Gradient High Magnetic Fields Affect Osteoblast Ultrastructure and Function by Disrupting Collagen I or Fibronectin/αβ1 Integrin

    PubMed Central

    Qian, Ai-Rong; Gao, Xiang; Zhang, Wei; Li, Jing-Bao; Wang, Yang; Di, Sheng-Meng; Hu, Li-Fang; Shang, Peng

    2013-01-01

    The superconducting magnet generates a field and field gradient product that can levitate diamagnetic materials. In this study a specially designed superconducting magnet with a large gradient high magnetic field (LG-HMF), which can provide three apparent gravity levels (μ-g, 1-g, and 2-g), was used to simulate a space-like gravity environment. The effects of LG-HMF on the ultrastructure and function of osteoblast-like cells (MG-63 and MC3T3-E1) and the underlying mechanism were investigated by transmission electromicroscopy (TEM), MTT, and cell western (ICW) assays. Under LG-HMF significant morphologic changes in osteoblast-like cells occurred, including expansion of endoplasmic reticulum and mitochondria, an increased number of lysosomes, distorted microvilli, and aggregates of actin filaments. Compared to controls, cell viability and alkaline phosphatase (ALP) secretion were significantly increased, and collagen I (col I), fibronectin (FN), vinculin, integrin α3, αv, and β1 expression were changed under LG-HMF conditions. In conclusion, LG-HMF affects osteoblast ultrastructure, cell viability, and ALP secretion, and the changes caused by LG-HMF may be related to disrupting col I or FN/αβ1 integrin. PMID:23382804

  11. Generalized form of anhysteretic magnetization function for Jiles-Atherton theory of hysteresis

    NASA Astrophysics Data System (ADS)

    Raghunathan, A.; Melikhov, Y.; Snyder, J. E.; Jiles, D. C.

    2009-10-01

    A generalized form of anhysteretic magnetization function to extend Jiles-Atherton theory to different forms of anisotropy has been derived. The general equation for the function has been compared with those of calculations made on the basis of known equations for specific cases: axially anisotropic (one-dimensional), planar anisotropic (two-dimensional), and isotropic (three-dimensional). The Jiles-Atherton model using the proposed functional form of generalized anhysteretic magnetization function for anisotropy dependence has been validated and the necessary equations derived. It has been shown in this work that this functional form of anhysteretic magnetization with necessary boundary conditions can be reduced to the familiar specific model equations in the particular cases.

  12. Longitudinal wave function control in single quantum dots with an applied magnetic field

    PubMed Central

    Cao, Shuo; Tang, Jing; Gao, Yunan; Sun, Yue; Qiu, Kangsheng; Zhao, Yanhui; He, Min; Shi, Jin-An; Gu, Lin; Williams, David A.; Sheng, Weidong; Jin, Kuijuan; Xu, Xiulai

    2015-01-01

    Controlling single-particle wave functions in single semiconductor quantum dots is in demand to implement solid-state quantum information processing and spintronics. Normally, particle wave functions can be tuned transversely by an perpendicular magnetic field. We report a longitudinal wave function control in single quantum dots with a magnetic field. For a pure InAs quantum dot with a shape of pyramid or truncated pyramid, the hole wave function always occupies the base because of the less confinement at base, which induces a permanent dipole oriented from base to apex. With applying magnetic field along the base-apex direction, the hole wave function shrinks in the base plane. Because of the linear changing of the confinement for hole wave function from base to apex, the center of effective mass moves up during shrinking process. Due to the uniform confine potential for electrons, the center of effective mass of electrons does not move much, which results in a permanent dipole moment change and an inverted electron-hole alignment along the magnetic field direction. Manipulating the wave function longitudinally not only provides an alternative way to control the charge distribution with magnetic field but also a new method to tune electron-hole interaction in single quantum dots. PMID:25624018

  13. Self-assembly with orthogonal-imposed stimuli to impart structure and confer magnetic function to electrodeposited hydrogels.

    PubMed

    Li, Ying; Liu, Yi; Gao, Tieren; Zhang, Boce; Song, Yingying; Terrell, Jessica L; Barber, Nathan; Bentley, William E; Takeuchi, Ichiro; Payne, Gregory F; Wang, Qin

    2015-05-20

    A magnetic nanocomposite film with the capability of reversibly collecting functionalized magnetic particles was fabricated by simultaneously imposing two orthogonal stimuli (electrical and magnetic). We demonstrate that cathodic codeposition of chitosan and Fe3O4 nanoparticles while simultaneously applying a magnetic field during codeposition can (i) organize structure, (ii) confer magnetic properties, and (iii) yield magnetic films that can perform reversible collection/assembly functions. The magnetic field triggered the self-assembly of Fe3O4 nanoparticles into hierarchical "chains" and "fibers" in the chitosan film. For controlled magnetic properties, the Fe3O4-chitosan film was electrodeposited in the presence of various strength magnetic fields and different deposition times. The magnetic properties of the resulting films should enable broad applications in complex devices. As a proof of concept, we demonstrate the reversible capture and release of green fluorescent protein (EGFP)-conjugated magnetic microparticles by the magnetic chitosan film. Moreover, antibody-functionalized magnetic microparticles were applied to capture cells from a sample, and these cells were collected, analyzed, and released by the magnetic chitosan film, paving the way for applications such as reusable biosensor interfaces (e.g., for pathogen detection). To our knowledge, this is the first report to apply a magnetic field during the electrodeposition of a hydrogel to generate magnetic soft matter. Importantly, the simple, rapid, and reagentless fabrication methodologies demonstrated here are valuable features for creating a magnetic device interface. PMID:25923335

  14. Cannabidiol promotes browning in 3T3-L1 adipocytes.

    PubMed

    Parray, Hilal Ahmad; Yun, Jong Won

    2016-05-01

    Recruitment of the brown-like phenotype in white adipocytes (browning) and activation of existing brown adipocytes are currently being investigated as a means to combat obesity. Thus, a wide variety of dietary agents that contribute to browning of white adipocytes have been identified. The present study was designed to investigate the effects of cannabidiol (CBD), a major nonpsychotropic phytocannabinoid of Cannabis sativa, on induction of browning in 3T3-L1 adipocytes. CBD enhanced expression of a core set of brown fat-specific marker genes (Ucp1, Cited1, Tmem26, Prdm16, Cidea, Tbx1, Fgf21, and Pgc-1α) and proteins (UCP1, PRDM16, and PGC-1α). Increased expression of UCP1 and other brown fat-specific markers contributed to the browning of 3T3-L1 adipocytes possibly via activation of PPARγ and PI3K. In addition, CBD increased protein expression levels of CPT1, ACSL, SIRT1, and PLIN while down-regulating JNK2, SREBP1, and LPL. These data suggest possible roles for CBD in browning of white adipocytes, augmentation of lipolysis, thermogenesis, and reduction of lipogenesis. In conclusion, the current data suggest that CBD plays dual modulatory roles in the form of inducing the brown-like phenotype as well as promoting lipid metabolism. Thus, CBD may be explored as a potentially promising therapeutic agent for the prevention of obesity. PMID:27067870

  15. A 3T Sodium and Proton Composite Array Breast Coil

    PubMed Central

    Kaggie, Joshua D.; Hadley, J. Rock; Badal, James; Campbell, John R.; Park, Daniel J.; Parker, Dennis L.; Morrell, Glen; Newbould, Rexford D.; Wood, Ali F.; Bangerter, Neal K.

    2013-01-01

    Purpose The objective of this study was to determine whether a sodium phased array would improve sodium breast MRI at 3T. The secondary objective was to create acceptable proton images with the sodium phased array in place. Methods A novel composite array for combined proton/sodium 3T breast MRI is compared to a coil with a single proton and sodium channel. The composite array consists of a 7-channel sodium receive array, a larger sodium transmit coil, and a 4-channel proton transceive array. The new composite array design utilizes smaller sodium receive loops than typically used in sodium imaging, uses novel decoupling methods between the receive loops and transmit loops, and uses a novel multi-channel proton transceive coil. The proton transceive coil reduces coupling between proton and sodium elements by intersecting the constituent loops to reduce their mutual inductance. The coil used for comparison consists of a concentric sodium and proton loop with passive decoupling traps. Results The composite array coil demonstrates a 2–5x improvement in SNR for sodium imaging and similar SNR for proton imaging when compared to a simple single-loop dual resonant design. Conclusion The improved SNR of the composite array gives breast sodium images of unprecedented quality in reasonable scan times. PMID:24105740

  16. Structure, function, and use of the magnetic sense in animals (invited)

    NASA Astrophysics Data System (ADS)

    Walker, Michael M.; Diebel, Carol E.; Green, Colin R.

    2000-05-01

    The hypothesis that animals navigate magnetically is attractive because the earth's magnetic field provides consistent information about position and direction in all environments through which animals travel. However, the hypothesis has been difficult to test because (i) the structure and function of the sense could not readily be analyzed in the laboratory and (ii) the effects of experimental treatments on behavior in the laboratory and field could not be reliably predicted. Our research is focused on the structure and function of the sense in rainbow trout and on applying the understanding gained in the laboratory to studies of navigation by homing pigeons. We have found iron-rich crystals (most likely single-domain magnetite) in candidate magnetoreceptor cells located within a discrete layer of sensory tissue in the nose of rainbow trout. The candidate receptor cells are closely associated with a branch of the trigeminal nerve that responds to changes in intensity but not direction of magnetic fields. In parallel work, we have developed a model of magnetic position determination in which pigeons derive magnetic analogues of geographic latitude and longitude from (i) the total intensity and (ii) the direction of the intensity slope of the earth's magnetic field. Taken together with our other results, the model gives us confidence that a coherent understanding of the structure, function, and use of the magnetic sense in animals is now developing.

  17. High-permeability functionalized silicone magnetic microspheres with low autofluorescence for biomedical applications.

    PubMed

    Evans, Benjamin A; Ronecker, Julia C; Han, David T; Glass, Daniel R; Train, Tonya L; Deatsch, Alison E

    2016-05-01

    Functionalized magnetic microspheres are widely used for cell separations, isolation of proteins and other biomolecules, in vitro diagnostics, tissue engineering, and microscale force spectroscopy. We present here the synthesis and characterization of a silicone magnetic microsphere which can be produced in diameters ranging from 0.5 to 50μm via emulsion polymerization of a silicone ferrofluid precursor. This bottom-up approach to synthesis ensures a uniform magnetic concentration across all sizes, leading to significant advances in magnetic force generation. We demonstrate that in a size range of 5-20μm, these spheres supply a full order of magnitude greater magnetic force than leading commercial products. In addition, the unique silicone matrix exhibits autofluorescence two orders of magnitude lower than polystyrene microspheres. Finally, we demonstrate the ability to chemically functionalize our silicone microspheres using a standard EDC reaction, and show that our folate-functionalized silicone microspheres specifically bind to targeted HeLa and Jurkat cells. These spheres show tremendous potential for replacing magnetic polystyrene spheres in applications which require either large magnetic forces or minimal autofluorescence, since they represent order-of-magnitude improvements in each. In addition, the unique silicone matrix and proven biocompatibility suggest that they may be useful for encapsulation and targeted delivery of lipophilic pharmaceuticals. PMID:26952493

  18. Extract of Chaga mushroom (Inonotus obliquus) stimulates 3T3-L1 adipocyte differentiation.

    PubMed

    Joo, Jeong In; Kim, Dong Hyun; Yun, Jong Won

    2010-11-01

    Chaga mushroom (Inonotus obliquus) has long been used as a folk medicine due to its numerous biological functions such as antibacterial, antiallergic, antiinflammatory and antioxidative activities. In the present study, it was found that the I. obliquus hot water extract (IOWE) activated adipogenesis of 3T3-L1 preadipocytes. Even in the absence of adipogenic stimuli by insulin, the IOWE strongly induced adipogenesis of 3T3-L1 preadipocytes. The major constituent of IOWE was glucose-rich polysaccharides with a molecular mass of 149  kDa. IOWE enhanced the differentiation of 3T3-L1 preadipocytes, increasing TG (triacylglycerol) accumulation that is critical for acquisition of the adipocyte phenotype, in a dose-dependent manner. IOWE stimulated gene expression of C/EBPα (CCAAT/enhancer-binding protein α) and PPARγ (peroxisome proliferator-activated receptors γ) during adipocyte differentiation, and induced the expression of PPARγ target genes such as aP2 (adipocyte protein 2), LPL (lipoprotein lipase) and CD36 (fatty acid translocase). Immunoblot analysis revealed that IOWE increased the expression of adipogenic makers such as PPARγ and GLUT4 (glucose transporter 4). The luciferase reporter assay demonstrated that IOWE did not exhibit PPARγ ligand activity. Although these results require further investigation, the ability of natural mushroom product to increase PPARγ transcriptional activities may be expected to be therapeutic targets for dyslipidemia and type 2 diabetes. PMID:21031614

  19. Sclerostin Enhances Adipocyte Differentiation in 3T3-L1 Cells.

    PubMed

    Ukita, Mayumi; Yamaguchi, Taihiko; Ohata, Noboru; Tamura, Masato

    2016-06-01

    Sclerostin, a secreted protein encoded by the Sost gene, is produced by osteocytes and is inhibited by osteoblast differentiation and bone formation. Recently, a functional association between bone and fat tissue has been suggested, and a correlation between circulating sclerostin levels and lipid metabolism has been reported in humans. However, the effects of sclerostin on adipogenesis remain unexplored. In the present study, we examined the role of sclerostin in regulating adipocyte differentiation using 3T3-L1 preadipocytes. In these cells, sclerostin enhanced adipocyte-specific gene expression and the accumulation of lipid deposits. Sclerostin also upregulated CCAAT/enhancer binding protein β expression but not cell proliferation and caspase-3/7 activities. Sclerostin also attenuated canonical Wnt3a-inhibited adipocyte differentiation. Recently, the transcriptional modulator TAZ has been involved in the canonical Wnt signaling pathway. Sclerostin reduced TAZ-responsive transcriptional activity and TAZ-responsive gene expression. Transfection of 3T3-L1 cells with TAZ siRNA increased the lipid deposits and adipogenic gene expression. These results show that sclerostin upregulates adipocyte differentiation in 3T3-L1 cells, suggesting a possible role for the osteocyte-derived sclerostin as a regulator of fat metabolism and as a reciprocal regulator of bone and adipose tissues metabolism. J. Cell. Biochem. 117: 1419-1428, 2016. © 2015 Wiley Periodicals, Inc. PMID:26553151

  20. Ginkgolide C Suppresses Adipogenesis in 3T3-L1 Adipocytes via the AMPK Signaling Pathway

    PubMed Central

    Liou, Chian-Jiun; Lai, Xuan-Yu; Chen, Ya-Ling; Wang, Chia-Ling; Wei, Ciao-Han; Huang, Wen-Chung

    2015-01-01

    Ginkgolide C, isolated from Ginkgo biloba leaves, is a flavone reported to have multiple biological functions, from decreased platelet aggregation to ameliorating Alzheimer disease. The study aim was to evaluate the antiadipogenic effect of ginkgolide C in 3T3-L1 adipocytes. Ginkgolide C was used to treat differentiated 3T3-L1 cells. Cell supernatant was collected to assay glycerol release, and cells were lysed to measure protein and gene expression related to adipogenesis and lipolysis by western blot and real-time PCR, respectively. Ginkgolide C significantly suppressed lipid accumulation in differentiated adipocytes. It also decreased adipogenesis-related transcription factor expression, including peroxisome proliferator-activated receptor and CCAAT/enhancer-binding protein. Furthermore, ginkgolide C enhanced adipose triglyceride lipase and hormone-sensitive lipase production for lipolysis and increased phosphorylation of AMP-activated protein kinase (AMPK), resulting in decreased activity of acetyl-CoA carboxylase for fatty acid synthesis. In coculture with an AMPK inhibitor (compound C), ginkgolide C also improved activation of sirtuin 1 and phosphorylation of AMPK in differentiated 3T3-L1 cells. The results suggest that ginkgolide C is an effective flavone for increasing lipolysis and inhibiting adipogenesis in adipocytes through the activated AMPK pathway. PMID:26413119

  1. Two-axis acceleration of functional connectivity magnetic resonance imaging by parallel excitation of phase-tagged slices and half k-space acceleration.

    PubMed

    Jesmanowicz, Andrzej; Nencka, Andrew S; Li, Shi-Jiang; Hyde, James S

    2011-01-01

    Whole brain functional connectivity magnetic resonance imaging requires acquisition of a time course of gradient-recalled (GR) volumetric images. A method is developed to accelerate this acquisition using GR echo-planar imaging and radio frequency (RF) slice phase tagging. For N-fold acceleration, a tailored RF pulse excites N slices using a uniform-field transmit coil. This pulse is the Fourier transform of the profile for the N slices with a predetermined RF phase tag on each slice. A multichannel RF receive coil is used for detection. For n slices, there are n/N groups of slices. Signal-averaged reference images are created for each slice within each slice group for each member of the coil array and used to separate overlapping images that are simultaneously received. The time-overhead for collection of reference images is small relative to the acquisition time of a complete volumetric time course. A least-squares singular value decomposition method allows image separation on a pixel-by-pixel basis. Twofold slice acceleration is demonstrated using an eight-channel RF receive coil, with application to resting-state functional magnetic resonance imaging in the human brain. Data from six subjects at 3 T are reported. The method has been extended to half k-space acquisition, which not only provides additional acceleration, but also facilitates slice separation because of increased signal intensity of the central lines of k-space coupled with reduced susceptibility effects. PMID:22432957

  2. Brain Activation during Semantic Processing in Autism Spectrum Disorders via Functional Magnetic Resonance Imaging

    ERIC Educational Resources Information Center

    Harris, Gordon J.; Chabris, Christopher F.; Clark, Jill; Urban, Trinity; Aharon, Itzhak; Steele, Shelley; McGrath, Lauren; Condouris, Karen; Tager-Flusberg, Helen

    2006-01-01

    Language and communication deficits are core features of autism spectrum disorders (ASD), even in high-functioning adults with ASD. This study investigated brain activation patterns using functional magnetic resonance imaging in right-handed adult males with ASD and a control group, matched on age, handedness, and verbal IQ. Semantic processing in…

  3. Irregular wave functions of a hydrogen atom in a uniform magnetic field

    SciTech Connect

    Wintgen, D. Max-Planck-Institut fuer Kernphysik, Postfach 103980, D-6900 Heidelberg, ); Honig, A. )

    1989-10-02

    We study the irregular wave functions of a highly excited hydrogen atom in a uniform magnetic field. The scarring of wave functions by periodic orbits is quantitatively investigated. The shape of unperturbed scars is in good agreement with recent semiclassical predictions.

  4. Wide-band complex magnetic susceptibility measurements of magnetic fluids as a function of temperature

    NASA Astrophysics Data System (ADS)

    Fannin, P. C.; Kinsella, L.; Charles, S. W.

    1999-07-01

    Measurements of the complex magnetic susceptibility over the frequency and temperature ranges of 2 MHz-6 GHz and 20 to -100°C, respectively, are reported for the first time for a magnetic fluid. The fluid used was a colloidal suspension of magnetite particles of median diameter 9 nm in a hydrocarbon oil (isopar m). Resonance was observed and found to increase from approx 1.5 GHz to 3.3 GHz in the temperature range 20 to -50°C. The increase in resonant frequency is attributed to a decrease in thermal fluctuations with decrease in temperature. At frequencies below approximately 19 MHz, a significant drop in χ'( ω) with decrease in temperature over the temperature range 20 to -100°C, is observed and is attributed to the changes in the Néel and Brownian relaxation processes. Below -60°C, the temperature at which the suspension becomes solid, Brownian relaxation ceases to exist.

  5. Equation of state and spin-correlation functions of ultrasmall classical Heisenberg magnets

    SciTech Connect

    Ciftja, O.; Luban, M.; Auslender, M.; Luscombe, J.H.

    1999-10-01

    We obtain analytical expressions for the total magnetic moment and the static spin-correlation functions of the classical Heisenberg model for ultrasmall systems of spins (unit vectors), that interact via isotropic, nearest-neighbor (n-n) exchange and that are subject to a uniform dc magnetic field of arbitrary strength. Explicit results are presented for the dimer, equilateral triangle, square, and regular tetrahedron arrays of spins. These systems provide a useful theoretical framework for calculating the magnetic properties of several recently synthesized molecular magnets. The tetrahedron as well as the equilateral triangle systems, each considered for n-n antiferromagnetic exchange, are of particular interest since they exhibit frustrated spin ordering for sufficiently low temperatures and weak magnetic fields. {copyright} {ital 1999} {ital The American Physical Society}

  6. Effects of the substrate on graphone magnetism: A density functional theory study

    NASA Astrophysics Data System (ADS)

    Buonocore, Francesco; Mosca Conte, Adriano; Lisi, Nicola

    2016-04-01

    The magnetism of graphone, a single-side-hydrogenated graphene derivative, has been related to the localized and unpaired p-electrons associated with the unhydrogenated carbon atoms. In the present density functional theory study, the effects the adhesion to either Cu(111) or α-quartz (0001) surface on the magnetic properties of graphone have been investigated. The total magnetization of the graphone adsorbed to copper and quartz surface is reduced by four and two times, respectively, with respect to the isolated graphone. We have shown there is electronic charge transfer from surface towards three-fold coordinated C atoms of graphone, but the main role in the partial magnetism quenching is played by bond formation and the consequent electron pairing of p-electrons. The critical temperature has been investigated on the basis of the mean field theory to evaluate the stability of the magnetism at ordinary temperature.

  7. Multi-functional Magnetic Nanoparticles for Magnetic Resonance Imaging and Cancer Therapy

    PubMed Central

    Yallapu, Murali M.; Othman, Shadi F.; Curtis, Evan T.; Gupta, Brij K.; Jaggi, Meena; Chauhan, Subhash C.

    2010-01-01

    We have developed a multi-layer approach for the synthesis of water-dispersible superparamagnetic iron oxide nanoparticles for hyperthermia, magnetic resonance imaging (MRI) and drug delivery applications. In this approach, iron oxide core nanoparticles were obtained by precipitation of iron salts in the presence of ammonia and provided β-cyclodextrin and pluronic polymer (F127) coatings. This formulation (F127250) was highly water dispersible which allowed encapsulation of the anti-cancer drug(s) in β-cyclodextrin and pluronic polymer for sustained drug release. The F127250 formulation has exhibited superior hyperthermia effects over time under alternating magnetic field compared to pure magnetic nanoparticles (MNP) and β-cyclodextrin coated nanoparticles (CD200). Additionally, the improved MRI characteristics were also observed for the F127250 formulation in agar gel and in cisplatin resistant ovarian cancer cells (A12780CP) compared to MNP and CD200 formulations. Furthermore, the drug loaded formulation of F127250 exhibited many folds of imaging contrast properties. Due to the internalization capacity of the F127250 formulation, its curcumin loaded formulation (F127250-CUR) exhibited almost equivalent inhibition effects on A2780CP (ovarian), MDA-MB-231 (breast), and PC3 (prostate) cancer cells even though curcumin release was only 40%. The improved therapeutic effects were verified by examining molecular effects using Western blotting and transmission electron microscopic (TEM) studies. F127250-CUR also exhibited haemocompatibility, suggesting a nanochemo-therapuetic agent for cancer therapy. PMID:21167595

  8. Functionalization of magnetic nanoparticles with 3-aminopropyl silane

    NASA Astrophysics Data System (ADS)

    Čampelj, Stanislav; Makovec, Darko; Drofenik, Miha

    2009-05-01

    Superparamagnetic maghemite nanoparticles were functionalized with 3-aminopropyl triethoxy silane (APS). The influence of the different experimental parameters (temperature, pH, and reactant concentration) on the efficiency of the APS bonding directly to the maghemite nanoparticles or after their coating with a thin layer of silica was systematically studied. The functionalization was followed with measurements of the ζ-potential and direct measurements of the surface APS concentration on the nanoparticles. The surface concentration of the APS was much higher in the case when the APS was bonded to the silica-coated nanoparticles compared to bonding directly to the surfaces of the iron-oxide nanoparticles.

  9. New pyrano-pyrone from Goniothalamus tamirensis enhances the proliferation and differentiation of osteoblastic MC3T3-E1 cells.

    PubMed

    Tai, Bui Huu; Huyen, Vu Thi; Huong, Tran Thu; Nhiem, Nguyen Xuan; Choi, Eun-Mi; Kim, Jeong Ah; Long, Pham Quoc; Cuong, Nguyen Manh; Kim, Young Ho

    2010-04-01

    The new pyrano-pyrone, (+)-8-epi-9-deoxygoniopypyrone (1) and (+)-9-deoxygoniopypyrone (2) were isolated from a chloroform extract of Goniothalamus tamirensis leaves. Their absolute stereostructures were discussed and confirmed by using infrared (IR), Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR-MS), one (1D) and two-dimensional (2D) nuclear magnetic resonance (NMR) spectra, Mosher's method, and comparison with the known compounds leiocapin A (3), deoxygoniopypyrone A (4), and (-)-8-epi-9-deoxygoniopypyrone (5). At concentrations of 2.67 microM, compounds 1 and 2 significantly increased the growth of osteoblastic MC3T3-E1 cells and caused a significant elevation of collagen content, alkaline phosphatase activity, and nodule mineralization in the cells (p<0.05). Our data suggest that the enhancement of osteoblast function by 1 and 2 may result in the prevention of osteoporosis. PMID:20410636

  10. Magnetic probe response function calibrations for plasma equilibrium reconstructions of CDX-U

    SciTech Connect

    Spaleta, J.; Zakharov, L.; Kaita, R.; Majeski, R.; Gray, T.

    2006-10-15

    A novel response function calibration technique has been developed to account for time-dependent nonaxisymmetric eddy currents near magnetic sensors in toroidal magnetic confinement devices. The response function technique provides a means to cross calibrate against all available external field coil systems to calculate the absolute sensitivity of each magnetic field sensor, even when induced eddy currents are present in the vacuum vessel wall. The response function information derived in the calibration process can be used in equilibrium reconstructions to separate plasma signals from signals due to externally produced eddy currents at magnetic field sensor locations, without invoking localized wall current distribution details. The response function technique was used for the first ever equilibrium reconstructions of spherical torus plasmas, when applied to the Current Drive Experiment-Upgrade (CDX-U) device. In conjunction with the equilibrium and stability code (ESC), equilibria were obtained for recent CDX-U experiments with lithium plasma-facing components. A description of the CDX-U magnetic sensor configuration and the response function calibration technique will be presented along with examples of resulting plasma equilibrium for CDX-U lithium wall operations.

  11. Challenging the spin accumulation interpretation of local ``3T'' measurements

    NASA Astrophysics Data System (ADS)

    Tinkey, Holly; Appelbaum, Ian; Li, Pengke

    2015-03-01

    The recent observation of magnetoresistance in local ``three-terminal'' (3T) measurements on ferromagnet/ insulator/ semiconductor junctions have spawned many claims of direct bulk spin injection or ``accumulation''. We present a self-consistent model to rigorously calculate expected voltage changes due to electrochemical potential splitting from spin accumulation driven by pure elastic tunnel injection in such junctions, and find that the experimentally observed magnetoresistance vastly exceeds theoretical predictions in all doping, temperature, and bias voltage regimes. Our own experimental measurements using inelastic electron tunneling spectroscopy reveal that extrinsic impurities and defects within the junctions are responsible for the observed magnetoresistance signals, which cannot possibly be attributed to spin dephasing of polarized bulk electrons from elastic injection as claimed by proponents of the method. Supported by the Maryland Nanocenter, the Office of Naval Research Contract N000141110637, the National Science Foundation contracts ECCS-0901941 and ECCS-1231855 and Graduate Fellowship DGE13221, and the Defense Threat Reduction Agency contract HDTRA1.

  12. A comprehensive neuropsychological mapping battery for functional magnetic resonance imaging.

    PubMed

    Karakas, Sirel; Baran, Zeynel; Ceylan, Arzu Ozkan; Tileylioglu, Emre; Tali, Turgut; Karakas, Hakki Muammer

    2013-11-01

    Existing batteries for FMRI do not precisely meet the criteria for comprehensive mapping of cognitive functions within minimum data acquisition times using standard scanners and head coils. The goal was to develop a battery of neuropsychological paradigms for FMRI that can also be used in other brain imaging techniques and behavioural research. Participants were 61 healthy, young adult volunteers (48 females and 13 males, mean age: 22.25 ± 3.39 years) from the university community. The battery included 8 paradigms for basic (visual, auditory, sensory-motor, emotional arousal) and complex (language, working memory, inhibition/interference control, learning) cognitive functions. Imaging was performed using standard functional imaging capabilities (1.5-T MR scanner, standard head coil). Structural and functional data series were analysed using Brain Voyager QX2.9 and Statistical Parametric Mapping-8. For basic processes, activation centres for individuals were within a distance of 3-11 mm of the group centres of the target regions and for complex cognitive processes, between 7 mm and 15 mm. Based on fixed-effect and random-effects analyses, the distance between the activation centres was 0-4 mm. There was spatial variability between individual cases; however, as shown by the distances between the centres found with fixed-effect and random-effects analyses, the coordinates for individual cases can be used to represent those of the group. The findings show that the neuropsychological brain mapping battery described here can be used in basic science studies that investigate the relationship of the brain to the mind and also as functional localiser in clinical studies for diagnosis, follow-up and pre-surgical mapping. PMID:23892066

  13. Uniform DT 3T burn: computations and sensitivities

    SciTech Connect

    Vold, Erik; Hryniw, Natalia; Hansen, Jon A; Kesler, Leigh A; Li, Frank

    2011-01-27

    A numerical model was developed in C to integrate the nonlinear deutrium-tritium (DT) burn equations in a three temperature (3T) approximation for spatially uniform test problems relevant to Inertial Confinement Fusion (ICF). Base model results are in excellent agreement with standard 3T results. Data from NDI, SESAME, and TOPS databases is extracted to create fits for the reaction rate parameter, the Planck opacity, and the coupling frequencies of the plasma temperatures. The impact of different fits (e.g., TOPS versus SESAME opacity data, higher order polynomial fits ofNDI data for the reaction rate parameter) were explored, and sensitivity to several model inputs are presented including: opacity data base, Coulomb logarithm, and Bremsstrahlung. Sensitivity to numerical integration time step size, and the relative insensitivity to the discretized numerics and numerical integration method was demonstrated. Variations in the IC for densities and temperatures were explored, showing similar DT burn profiles in most cases once ignition occurs. A coefficient multiplying the Compton coupling term (default, A = 1) can be adjusted to approximate results from more sophisticated models. The coefficient was reset (A = 0.4) to match the maximum temperatures resulting from standard multi-group simulations of the base case test problem. Setting the coefficient to a larger value, (A = 0.6) matches maximum ion temperatures in a kinetic simulation of a high density ICF-like regime. Matching peak temperatures does not match entire temperature-time profiles, indicating the Compton coefficient is density and time dependent as the photon distribution evolves. In the early time burn during the ignition of the DT, the present model with modified Compton coupling provides a very simple method to obtain a much improved match to the more accurate solution from the multi-group radiation model for these DT burn regimes.

  14. Nanometric resolution magnetic resonance imaging methods for mapping functional activity in neuronal networks

    PubMed Central

    Boretti, Albert; Castelletto, Stefania

    2016-01-01

    This contribution highlights and compares some recent achievements in the use of k-space and real space imaging (scanning probe and wide-filed microscope techniques), when applied to a luminescent color center in diamond, known as nitrogen vacancy (NV) center. These techniques combined with the optically detected magnetic resonance of NV, provide a unique platform to achieve nanometric magnetic resonance imaging (MRI) resolution of nearby nuclear spins (known as nanoMRI), and nanometric NV real space localization. • Atomic size optically detectable spin probe. • High magnetic field sensitivity and nanometric resolution. • Non-invasive mapping of functional activity in neuronal networks. PMID:27144128

  15. Nanometric resolution magnetic resonance imaging methods for mapping functional activity in neuronal networks.

    PubMed

    Boretti, Albert; Castelletto, Stefania

    2016-01-01

    This contribution highlights and compares some recent achievements in the use of k-space and real space imaging (scanning probe and wide-filed microscope techniques), when applied to a luminescent color center in diamond, known as nitrogen vacancy (NV) center. These techniques combined with the optically detected magnetic resonance of NV, provide a unique platform to achieve nanometric magnetic resonance imaging (MRI) resolution of nearby nuclear spins (known as nanoMRI), and nanometric NV real space localization. •Atomic size optically detectable spin probe.•High magnetic field sensitivity and nanometric resolution.•Non-invasive mapping of functional activity in neuronal networks. PMID:27144128

  16. Physiological Noise Reduction Using Volumetric Functional Magnetic Resonance Inverse Imaging

    PubMed Central

    Lin, Fa-Hsuan; Nummenmaa, Aapo; Witzel, Thomas; Polimeni, Jonathan R.; Zeffiro, Thomas A.; Wang, Fu-Nien; Belliveau, John W.

    2013-01-01

    Physiological noise arising from a variety of sources can significantly degrade the detection of task-related activity in BOLD-contrast fMRI experiments. If whole head spatial coverage is desired, effective suppression of oscillatory physiological noise from cardiac and respiratory fluctuations is quite difficult without external monitoring, since traditional EPI acquisition methods cannot sample the signal rapidly enough to satisfy the Nyquist sampling theorem, leading to temporal aliasing of noise. Using a combination of high speed magnetic resonance inverse imaging (InI) and digital filtering, we demonstrate that it is possible to suppress cardiac and respiratory noise without auxiliary monitoring, while achieving whole head spatial coverage and reasonable spatial resolution. Our systematic study of the effects of different moving average (MA) digital filters demonstrates that a MA filter with a 2 s window can effectively reduce the variance in the hemodynamic baseline signal, thereby achieving 57-58% improvements in peak z-statistic values compared to unfiltered InI or spatially smoothed EPI data (FWHM =8.6 mm). In conclusion, the high temporal sampling rates achievable with InI permit significant reductions in physiological noise using standard temporal filtering techniques that result in significant improvements in hemodynamic response estimation. PMID:21954026

  17. Electron Velocity Distribution Function in Magnetic Clouds in the Solar Wind

    NASA Technical Reports Server (NTRS)

    Nieves-Chinchil, Teresa; Vinas, Adolfo F.; Bale, Stuart D.

    2006-01-01

    We present a study of the kinetic properties of the electron velocity distribution functions within magnetic clouds, since they are the dominant thermal component. The study is based on high time resolution data from the GSFC WIND/SWE electron spectrometer and the Berkeley 3DP electron plasma instruments. Recent studies on magnetic clouds have shown observational evidence of anti-correlation between the total electron density and electron temperature, which suggest a polytrope law P(sub e) = alpha(Nu(sub e) (sup gamma)) for electrons with the constant gamma approximates 0.5 < 1. This anti-correlation and small polytropic gamma-values is interpreted in the context of the presence of highly non-Maxwellian electron distributions (i.e. non-thermal) within magnetic clouds. These works suggested that the non-thermal electrons can contribute as much as 50% of the total electron pressure within magnetic clouds. We have revisited some of the magnetic cloud events previously studied and attempted to quantify the nature of the non-thermal electrons by modeling the electron velocity distribution function using a kappa distribution function to characterize the kinetic non-thermal effects. If non-thermal tail effects are the source for the anti-correlation between the moment electron temperature and density and if the kappa distribution is a reasonable representative model of non-thermal effects, then the electron velocity distribution within magnetic clouds should show indication for small K-values when gamma < 1.

  18. Fabrication and functionalization of dendritic poly(amidoamine)-immobilized magnetic polymer composite microspheres.

    PubMed

    Liu, Hongbo; Guo, Jia; Jin, Lan; Yang, Wuli; Wang, Changchun

    2008-03-20

    The synthesis of functionalized magnetic polymer microspheres was described by a process involving (1) preparation of the monodisperse magnetic seeds according to a two-step procedure including the preparation of bilayer-oleic acid-coated Fe3O4 nanoparticles followed by soap-free emulsion polymerization with methyl methacrylate (MMA) and divinyl benzene (a cross-linking agent, DVB); (2) seeded emulsion polymerization proceeding under the continuous addition of glycidyl methacrylate (GMA) monomers in the presence of the magnetic PMMA seeds; and (3) chemical modification of the PGMA shells with ethylenediamine (EDA) to yield amino groups. As such, the magnetic poly(MMA-DVB-GMA) microspheres were prepared possessing monodispersity, uniform magnetic properties, and abundant surface amino groups. Then, the dendritic poly(amidoamine) (PAMAM) shells were coated on the magnetic particles on the basis of the Michael addition of methyl acrylate and the amidation of the resulting ester with a large excess of EDA, which could achieve generational growth under such uniform stepwise reactions. For improving the luminescence properties of the composite particles, fluorescein isothiocyanate, which is a popular organic dye, was reacted with the terminal -NH2 groups from the dendritic PAMAM shells, resulting in the formation of multifunctional microspheres with excellent photoluminescence, superparamagnetic, and pH-sensitive properties. In this case, it can be expected that an extension of the functionalization of these microspheres is to immobilize other target molecules onto the PAMAM shells to introduce other desired functions for potential chemical and biological applications. PMID:18281972

  19. Tailored functionalization of iron oxide nanoparticles for MRI, drug delivery, magnetic separation and immobilization of biosubstances.

    PubMed

    Hola, Katerina; Markova, Zdenka; Zoppellaro, Giorgio; Tucek, Jiri; Zboril, Radek

    2015-11-01

    In this critical review, we outline various covalent and non-covalent approaches for the functionalization of iron oxide nanoparticles (IONPs). Tuning the surface chemistry and design of magnetic nanoparticles are described in relation to their applicability in advanced medical technologies and biotechnologies including magnetic resonance imaging (MRI) contrast agents, targeted drug delivery, magnetic separations and immobilizations of proteins, enzymes, antibodies, targeting agents and other biosubstances. We review synthetic strategies for the controlled preparation of IONPs modified with frequently used functional groups including amine, carboxyl and hydroxyl groups as well as the preparation of IONPs functionalized with other species, e.g., epoxy, thiol, alkane, azide, and alkyne groups. Three main coupling strategies for linking IONPs with active agents are presented: (i) chemical modification of amine groups on the surface of IONPs, (ii) chemical modification of bioactive substances (e.g. with fluorescent dyes), and (iii) the activation of carboxyl groups mainly for enzyme immobilization. Applications for drug delivery using click chemistry linking or biodegradable bonds are compared to non-covalent methods based on polymer modified condensed magnetic nanoclusters. Among many challenges, we highlight the specific surface engineering allowing both therapeutic and diagnostic applications (theranostics) of IONPs and magnetic/metallic hybrid nanostructures possessing a huge potential in biocatalysis, green chemistry, magnetic bioseparations and bioimaging. PMID:25689073

  20. Advances in functional magnetic resonance imaging of the human brainstem.

    PubMed

    Beissner, Florian; Schumann, Andy; Brunn, Franziska; Eisenträger, Daniela; Bär, Karl-Jürgen

    2014-02-01

    The brainstem is of tremendous importance for our daily survival, and yet the functional relationships between various nuclei, their projection targets, and afferent regulatory areas remain poorly characterized. The main reason for this lies in the sub-optimal performance of standard neuroimaging methods in this area. In particular, fMRI signals are much harder to detect in the brainstem region compared to cortical areas. Here we describe and validate a new approach to measure activation of brainstem nuclei in humans using standard fMRI sequences and widely available tools for statistical image processing. By spatially restricting an independent component analysis to an anatomically defined brainstem mask, we excluded those areas from the analysis that were strongly affected by physiological noise. This allowed us to identify for the first time intrinsic connectivity networks in the human brainstem and to map brainstem-cortical connectivity purely based on functionally defined regions of interest. PMID:23933038

  1. Nitric Oxide-Induced Autophagy in MC3T3-E1 Cells is Associated with Cytoprotection via AMPK Activation

    PubMed Central

    Yang, Jung Yoon; Park, Min Young; Park, Sam Young; Yoo, Hong Il; Kim, Min Seok; Kim, Jae Hyung

    2015-01-01

    Nitric oxide (NO) is important in the regulation of bone remodeling, whereas high concentration of NO promotes cell death of osteoblast. However, it is not clear yet whether NO-induced autophagy is implicated in cell death or survival of osteoblast. The present study is aimed to examine the role of NO-induced autophagy in the MC3T3-E1 cells and their underlying molecular mechanism. The effect of sodium nitroprusside (SNP), an NO donor, on the cytotoxicity of the MC3T3-E1 cells was determined by MTT assay and expression of apoptosis or autophagy associated molecules was evaluated by western blot analysis. The morphological observation of autophagy and apoptosis by acridine orange stain and TUNEL assay were performed, respectively. Treatment of SNP decreased the cell viability of the MC3T3-E1 cells in dose- and time-dependent manner. SNP increased expression levels of p62, ATG7, Beclin-1 and LC3-II, as typical autophagic markers and augmented acidic autophagolysosomal vacuoles, detected by acridine orange staining. However, pretreatment with 3-methyladenine (3MA), the specific inhibitor for autophagy, decreased cell viability, whereas increased the cleavage of PARP and caspase-3 in the SNP-treated MC3T3-E1 cells. AMP-activated protein kinase (AMPK), a major autophagy regulatory kinase, was activated in SNP-treated MC3T3-E1 cells. In addition, pretreatment with compound C, an inhibitor of AMPK, decreased cell viability, whereas increased the number of apoptotic cells, cleaved PARP and caspase-3 levels compared to those of SNP-treated MC3T3-E1 cells. Taken together, it is speculated that NO-induced autophagy functions as a survival mechanism via AMPK activation against apoptosis in the MC3T3-E1 cells. PMID:26557017

  2. The quiet Sun magnetic field observed with ZIMPOL on THEMIS. I. The probability density function

    NASA Astrophysics Data System (ADS)

    Bommier, V.; Martínez González, M.; Bianda, M.; Frisch, H.; Asensio Ramos, A.; Gelly, B.; Landi Degl'Innocenti, E.

    2009-11-01

    Context: The quiet Sun magnetic field probability density function (PDF) remains poorly known. Modeling this field also introduces a magnetic filling factor that is also poorly known. With these two quantities, PDF and filling factor, the statistical description of the quiet Sun magnetic field is complex and needs to be clarified. Aims: In the present paper, we propose a procedure that combines direct determinations and inversion results to derive the magnetic field vector and filling factor, and their PDFs. Methods: We used spectro-polarimetric observations taken with the ZIMPOL polarimeter mounted on the THEMIS telescope. The target was a quiet region at disk center. We analyzed the data by means of the UNNOFIT inversion code, with which we inferred the distribution of the mean magnetic field α B, α being the magnetic filling factor. The distribution of α was derived by an independent method, directly from the spectro-polarimetric data. The magnetic field PDF p(B) could then be inferred. By introducing a joint PDF for the filling factor and the magnetic field strength, we have clarified the definition of the PDF of the quiet Sun magnetic field when the latter is assumed not to be volume-filling. Results: The most frequent local average magnetic field strength is found to be 13 G. We find that the magnetic filling factor is related to the magnetic field strength by the simple law α = B_1/B with B1 = 15 G. This result is compatible with the Hanle weak-field determinations, as well as with the stronger field determinations from the Zeeman effect (kGauss field filling 1-2% of space). From linear fits, we obtain the analytical dependence of the magnetic field PDF. Our analysis has also revealed that the magnetic field in the quiet Sun is isotropically distributed in direction. Conclusions: We conclude that the quiet Sun is a complex medium where magnetic fields having different field strengths and filling factors coexist. Further observations with a better

  3. ``Green'' functionalization of magnetic nanoparticles via tea polyphenol for magnetic resonance/fluorescent dual-imaging

    NASA Astrophysics Data System (ADS)

    Jiang, Wen; Lai, Kuilin; Liu, Kexia; Xia, Rui; Gao, Fabao; Wu, Yao; Gu, Zhongwei

    2014-01-01

    Tea polyphenol serves as an environmentally friendly ligand-exchange molecule to synthesize multifunctional metal-doped superparamagnetic iron oxide nanoparticles via a catechol-metal coordination interaction. The resultant particles not only exhibit excellent hydrophilicity and protein adsorption resistance, but also are applicable as magnetic resonance/fluorescent dual-imaging probes due to their high T2 relaxivity, autofluorescence and large cellular uptake.Tea polyphenol serves as an environmentally friendly ligand-exchange molecule to synthesize multifunctional metal-doped superparamagnetic iron oxide nanoparticles via a catechol-metal coordination interaction. The resultant particles not only exhibit excellent hydrophilicity and protein adsorption resistance, but also are applicable as magnetic resonance/fluorescent dual-imaging probes due to their high T2 relaxivity, autofluorescence and large cellular uptake. Electronic supplementary information (ESI) available: Additional information and figures (Fig. S1-S7), including experimental sections, characterization of the products, protein corona analysis, cytotoxicity and cellular uptake quantification. See DOI: 10.1039/c3nr05003c

  4. Magnetizing of permanent magnets using HTS bulk magnets

    NASA Astrophysics Data System (ADS)

    Oka, Tetsuo; Muraya, Tomoki; Kawasaki, Nobutaka; Fukui, Satoshi; Ogawa, Jun; Sato, Takao; Terasawa, Toshihisa

    2012-01-01

    A demagnetized Nd-Fe-B permanent magnet was scanned just above the magnetic pole which contains the HTS bulk magnet generating a magnetic field of 3.27 T. The magnet sample was subsequently found to be fully magnetized in the open space of the static magnetic fields. We examined the magnetic field distributions when the magnetic poles were scanned twice to activate the magnet plate inversely with various overlap distances between the tracks of the bulk magnet. The magnetic field of the "rewritten" magnet reached the values of the magnetically saturated region of the material, showing steep gradients at the border of each magnetic pole. As a replacement for conventional pulse field magnetizing methods, this technique is proposed to expand the degree of freedom in the design of electromagnetic devices, and is proposed as a novel practical method for magnetizing rare-earth magnets, which have excellent magnetic performance and require intense fields of more than 3 T to be activated.

  5. Special Considerations for Functional Magnetic Resonance Imaging of Pediatric Populations

    PubMed Central

    Kotsoni, Eleni; Byrd, Dana; Casey, BJ

    2010-01-01

    Functional MRI (fMRI) provides a non-invasive means of studying both typical and atypical brain development in vivo. However, the developmental and clinical status of the populations of interest impact how neuroimaging data should be collected, analyzed, and interpreted. In the present paper, we review methodological and theoretical issues relevant to developmental and clinical neuroimaging research and provide possible approaches for addressing each. These issues include accounting for differences in biological noise, neuroanatomy, motion, and task performance. Finally, we emphasize the importance of a converging methods approach in constraining and supporting interpretations of pediatric imaging results. PMID:16649204

  6. Functional magnetic resonance imaging for defining the biological target volume

    PubMed Central

    Kauczor, Hans-Ulrich; Zechmann, Christian; Stieltjes, Bram; Weber, Marc-Andre

    2006-01-01

    Morphology as demonstrated by CT is the basis for radiotherapy planning. Intensity-modulated and adaptive radiotherapy techniques would greatly benefit from additional functional information allowing for definition of the biological target volume. MRI techniques include several which can characterize and quantify different tissue properties and their tumour-related changes. Results of perfusion MRI represent microvascular density and permeability; MR spectroscopy depicts particular metabolites; diffusion weighted imaging shows tissue at risk and tumour cellularity; while dynamic 3D acquisition (4D MRI) shows organ motion and the mobility of tumours within them. PMID:16766269

  7. EPAS1 promotes adipose differentiation in 3T3-L1 cells.

    PubMed

    Shimba, Shigeki; Wada, Taira; Hara, Shuntaro; Tezuka, Masakatsu

    2004-09-24

    Adipose differentiation is regulated by several transcription factors, such as the CAAT/enhancer-binding protein family and peroxisome proliferator activator (PPAR) gamma2. Several recent studies have shown that the basic helix-loop-helix-PAS superfamily is also involved in the regulation of adipose differentiation. In this study, we investigated the roles played by EPAS1 (endothelial PAS domain protein 1) in adipogenesis. EPAS1, also referred to as hypoxia-inducible factor 2alpha, is a transcription factor known to play essential roles in catecholamine homeostasis, vascular remodeling, and the maintenance of reactive oxygen species, and so forth. During adipose differentiation in 3T3-L1 cells, the level of EPAS1 mRNA began to increase 6 days after the induction, and EPAS1 was highly expressed in differentiated cells. To examine whether EPAS1 is involved in adipogenesis, we first isolated stable clones from 3T3-L1 cells in which we could induce the expression of an EPAS1 C-terminal deletion mutant (designated EPAS1-(1-485)) with the insect hormone. The induction of EPAS1-(1-485) allowed the cells to accumulate only minimum amounts of intracellular lipid droplets. Consistent with the morphological observations, a minimum amount of aP2 and PPARgamma2 mRNA was induced in the EPAS1-(1-485) cells. We then examined whether or not EPAS1 was able to promote adipogenesis in NIH 3T3 cells, a relatively nonadipogenic cell line. Overexpression of EPAS1 in NIH 3T3 cells induced a significant amount of lipid accumulation compared with that of the control cells in the presence of the PPARgamma ligand. The results were also confirmed by measuring the expression of adipocyte-related genes. Adenovirus-mediated EPAS1-(1-485) expression resulted in the reduction of basal and insulin-dependent glucose transport in 3T3-L1 adipocytes. The mechanism involved the transcriptional regulation of GLUT1, GLUT4, and IRS3 expression by EPAS1. Taken together, these results suggest that EPAS1 plays

  8. Vortex fluidic entrapment of functional microalgal cells in a magnetic polymer matrix

    NASA Astrophysics Data System (ADS)

    Eroglu, Ela; D'Alonzo, Nicholas J.; Smith, Steven M.; Raston, Colin L.

    2013-03-01

    Composite materials based on superparamagnetic magnetite nanoparticles embedded in polyvinylpyrrolidone (PVP) are generated in a continuous flow vortex fluidic device (VFD). The same device is effective in entrapping microalgal cells within this material, such that the functional cells can be retrieved from aqueous dispersions using an external magnet.Composite materials based on superparamagnetic magnetite nanoparticles embedded in polyvinylpyrrolidone (PVP) are generated in a continuous flow vortex fluidic device (VFD). The same device is effective in entrapping microalgal cells within this material, such that the functional cells can be retrieved from aqueous dispersions using an external magnet. Electronic supplementary information (ESI) available. See DOI: 10.1039/c3nr33813d

  9. Ab initio studies of mechanical, electric, and magnetic properties of functionalized carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Milowska, Karolina; Birowska, Magdalena; Majewski, Jacek A.

    2012-02-01

    We present results of extensive theoretical studies of mechanical, electric, and magnetic properties of functionalized carbon nanotubes (CNTs). Our studies are based on the ab initio calculations in the framework of the density functional theory. We have performed calculations for various metallic and semiconductor single wall CNTs, functionalized with simple organic molecules such as OH, COOH, NHn, CHn and metals, Al, Fe, Ni, Cu, Zn, and Pd. We have determined the stability of the functionalized CNTs, their elastic moduli, conductance, and magnetic moments (in the case of CNTs decorated with magnetic ions). These studies shed light on physical mechanisms governing the binding of the adsorbed molecules and also provide valuable quantitative predictions that are of importance for design of novel composite materials and functional devices. In particular, we find out that the Young's modulus of functionalized CNTs is smaller than in the case of bare CNTs, however it is large enough to provide a strong enforcement of composites. The functionalization with molecules leads also to the metallization of semiconducting CNTs, being relevant in the context of CNT interconnects, whereas the functionalization with metals might be used to cut CNTs into ribbons.

  10. Making Sense of Real-Time Functional Magnetic Resonance Imaging (rtfMRI) and rtfMRI Neurofeedback

    PubMed Central

    2015-01-01

    This review explains the mechanism of functional magnetic resonance imaging in general and specifically introduces real-time functional magnetic resonance imaging as a method for training self-regulation of brain activity. Using real-time functional magnetic resonance imaging neurofeedback, participants can acquire control over their own brain activity. In patients with neuropsychiatric disorders, this control can potentially have therapeutic implications. In this review, the technical requirements are presented and potential applications and limitations are discussed. PMID:25716778

  11. Surface functionalization for tailoring the aggregation and magnetic behaviour of silica-coated iron oxide nanostructures

    NASA Astrophysics Data System (ADS)

    Roca, A. G.; Carmona, D.; Miguel-Sancho, N.; Bomatí-Miguel, O.; Balas, F.; Piquer, C.; Santamaría, J.

    2012-04-01

    We report here a detailed structural and magnetic study of different silica nanocapsules containing uniform and highly crystalline maghemite nanoparticles. The magnetic phase consists of 5 nm triethylene glycol (TREG)- or dimercaptosuccinic acid (DMSA)-coated maghemite particles. TREG-coated nanoparticles were synthesized by thermal decomposition. In a second step, TREG ligands were exchanged by DMSA. After the ligand exchange, the ζ potential of the particles changed from - 10 to - 40 mV, whereas the hydrodynamic size remained constant at around 15 nm. Particles coated by TREG and DMSA were encapsulated in silica following a sol-gel procedure. The encapsulation of TREG-coated nanoparticles led to large magnetic aggregates, which were embedded in coalesced silica structures. However, DMSA-coated nanoparticles led to small magnetic clusters inserted in silica spheres of around 100 nm. The final nanostructures can be described as the result of several competing factors at play. Magnetic measurements indicate that in the TREG-coated nanoparticles the interparticle magnetic interaction scenario has not dramatically changed after the silica encapsulation, whereas in the DMSA-coated nanoparticles, the magnetic interactions were screened due to the function of the silica template. Moreover, the analysis of the AC susceptibility suggests that our systems essentially behave as cluster spin glass systems.

  12. Interfacial adsorption and surfactant release characteristics of magnetically functionalized halloysite nanotubes for responsive emulsions.

    PubMed

    Owoseni, Olasehinde; Nyankson, Emmanuel; Zhang, Yueheng; Adams, Daniel J; He, Jibao; Spinu, Leonard; McPherson, Gary L; Bose, Arijit; Gupta, Ram B; John, Vijay T

    2016-02-01

    Magnetically responsive oil-in-water emulsions are effectively stabilized by a halloysite nanotube supported superparamagnetic iron oxide nanoparticle system. The attachment of the magnetically functionalized halloysite nanotubes at the oil-water interface imparts magnetic responsiveness to the emulsion and provides a steric barrier to droplet coalescence leading to emulsions that are stabilized for extended periods. Interfacial structure characterization by cryogenic scanning electron microscopy reveals that the nanotubes attach at the oil-water interface in a side on-orientation. The tubular structure of the nanotubes is exploited for the encapsulation and release of surfactant species that are typical of oil spill dispersants such as dioctyl sulfosuccinate sodium salt and polyoxyethylene (20) sorbitan monooleate. The magnetically responsive halloysite nanotubes anchor to the oil-water interface stabilizing the interface and releasing the surfactants resulting in reduction in the oil-water interfacial tension. The synergistic adsorption of the nanotubes and the released surfactants at the oil-water interface results in oil emulsification into very small droplets (less than 20μm). The synergy of the unique nanotubular morphology and interfacial activity of halloysite with the magnetic properties of iron oxide nanoparticles has potential applications in oil spill dispersion, magnetic mobilization and detection using magnetic fields. PMID:26555959

  13. Electronic Structure Calculation of Permanent Magnets using the KKR Green's Function Method

    NASA Astrophysics Data System (ADS)

    Doi, Shotaro; Akai, Hisazumi

    2014-03-01

    Electronic structure and magnetic properties of permanent magnetic materials, especially Nd2Fe14B, are investigated theoretically using the KKR Green's function method. Important physical quantities in magnetism, such as magnetic moment, Curie temperature, and anisotropy constant, which are obtained from electronics structure calculations in both cases of atomic-sphere-approximation and full-potential treatment, are compared with past band structure calculations and experiments. The site preference of heavy rare-earth impurities are also evaluated through the calculation of formation energy with the use of coherent potential approximations. Further, the development of electronic structure calculation code using the screened KKR for large super-cells, which is aimed at studying the electronic structure of realistic microstructures (e.g. grain boundary phase), is introduced with some test calculations.

  14. Stability of a pinned magnetic domain wall as a function of its internal configuration

    SciTech Connect

    Montaigne, F.; Duluard, A.; Briones, J.; Lacour, D.; Hehn, M.; Childress, J. R.

    2015-01-14

    It is shown that there are many stable configurations for a domain wall pinned by a notch along a magnetic stripe. The stability of several of these configurations is investigated numerically as a function of the thickness of the magnetic film. The depinning mechanism depends on the structure of the domain wall and on the thickness of the magnetic film. In the case of a spin-valve structure, it appears that the stray fields emerging from the hard layer at the notch location influence the stability of the micromagnetic configuration. Different depinning mechanisms are thus observed for the same film thickness depending on the magnetization orientation of the propagating domain. This conclusion qualitatively explains experimental magnetoresistance measurements.

  15. Functionalization of monodisperse iron oxide NPs and their properties as magnetically recoverable catalysts.

    PubMed

    Gage, Samuel H; Stein, Barry D; Nikoshvili, Linda Zh; Matveeva, Valentina G; Sulman, Mikhail G; Sulman, Esther M; Morgan, David Gene; Yuzik-Klimova, Ekaterina Yu; Mahmoud, Waleed E; Bronstein, Lyudmila M

    2013-01-01

    Here we report the functionalization of monodisperse iron oxide nanoparticles (NPs) with commercially available functional acids containing multiple double bonds such as linolenic (LLA) and linoleic (LEA) acids or pyridine moieties such as 6-methylpyridine-2-carboxylic acid, isonicotinic acid, 3-hydroxypicolinic acid, and 6-(1-piperidinyl)pyridine-3-carboxlic acid (PPCA). Both double bonds and pyridine groups can be reacted with noble metal compounds to form catalytically active species in the exterior of magnetic NPs, thus making them promising magnetically recoverable catalysts. We determined that both LLA and LEA stabilize magnetic iron oxide NPs, allowing the formation of π-complexes with bis(acetonitrile)dichloropalladium(II) in the NP shells. In both cases, this leads to the formation of NP aggregates because of interparticle complexation. In the case of pyridine-containing ligands, only PPCA with two N-containing rings is able to provide NP stabilization and functionalization whereas other pyridine-containing acids did now allow sufficient steric stabilization. The interaction of PPCA-based particles with Pd acetate also leads to aggregation because of interparticle interactions, but the aggregates that are formed are much smaller. Nevertheless, the catalytic properties in the selective hydrogenation of dimethylethynylcarbinol (DMEC) to dimethylvinylcarbinol were the best for the catalyst based on LLA, demonstrating that the NP aggregates in all cases are penetrable for DMEC. Easy magnetic separation of this catalyst from the reaction solution makes it promising as a magnetically recoverable catalyst. PMID:23234434

  16. Magnetic two-photon scattering and two-photon emission - Cross sections and redistribution functions

    NASA Technical Reports Server (NTRS)

    Alexander, S. G.; Meszaros, P.

    1991-01-01

    The magnetic two-photon scattering cross section is discussed within the framework of QED, and the corresponding scattering redistribution function for this process and its inverse, as well as the scattering source function are calculated explicitly. In a similar way, the magnetic two-photon emission process which follows the radiative excitation of Landau levels above ground is calculated. The two-photon scattering and two-photon emission are of the same order as the single-photon magnetic scattering. All three of these processes, and in optically thick cases also their inverses, are included in radiative transport calculations modeling accreting pulsars and gamma-ray bursters. These processes play a prominent role in determining the relative strength of the first two cyclotron harmonics, and their effects extend also to the higher harmonics.

  17. Abnormal fusiform activation during emotional-face encoding assessed with functional magnetic resonance imaging.

    PubMed

    Adleman, Nancy E; Kayser, Reilly R; Olsavsky, Aviva K; Bones, Brian L; Muhrer, Eli J; Fromm, Stephen J; Pine, Daniel S; Zarate, Carlos; Leibenluft, Ellen; Brotman, Melissa A

    2013-05-30

    This functional magnetic resonance imaging study shows that children and adults with bipolar disorder (BD), compared with healthy subjects, exhibit impaired memory for emotional faces and abnormal fusiform activation during encoding. Fusiform activation abnormalities in BD were correlated with mania severity and may therefore represent a trait and state BD biomarker. PMID:23541333

  18. The synthesis and rheological characteristics of colloidal systems containing functional magnetic nanoparticles

    NASA Astrophysics Data System (ADS)

    Zaichenko, Alexander; Bolshakova, Inessa; Mitina, Nanalia; Shevchuk, Oleh; Bily, Alexander; Lobaz, Vladimir

    2005-03-01

    Functional magnetic nanoparticles were synthesized by homogeneous nucleation from the solution of metal salts in the presence of functional oligoperoxide surfactants (FOS). FOS addition causes the decrease of the quantity of large particles and agglomerates. The presence of radical forming sites on the magnetic colloid surface provides the possibility of carrying out of grafted polymerization in a wide temperature range in the media of various polarities. As a result of homogeneous nucleation of the particles in the presence of oligomer surfactants the extremes of the particle size, dynamic viscosity and maximal value of FOS sorption are observed at the same FOS concentration in the solution. The dependences of dynamic viscosity of magnetic colloid suspensions modified by various amount of FOS on shear stress witness the formation of multi-layer functional shell with different orientation of polar functional groups and their different remoteness from the surface. The formation of new polymeric chains tethered to the colloid surface leads to breaking particle assemblies and provides both the aggregative and sedimentation stabilization of the magnetic fluids formed and targeted affinity to biological substrates.

  19. Functional Magnetic Resonance Imaging of Cognitive Processing in Young Adults with Down Syndrome

    ERIC Educational Resources Information Center

    Jacola, Lisa M.; Byars, Anna W.; Chalfonte-Evans, Melinda; Schmithorst, Vincent J.; Hickey, Fran; Patterson, Bonnie; Hotze, Stephanie; Vannest, Jennifer; Chiu, Chung-Yiu; Holland, Scott K.; Schapiro, Mark B.

    2011-01-01

    The authors used functional magnetic resonance imaging (fMRI) to investigate neural activation during a semantic-classification/object-recognition task in 13 persons with Down syndrome and 12 typically developing control participants (age range = 12-26 years). A comparison between groups suggested atypical patterns of brain activation for the…

  20. A Functional Magnetic Resonance Imaging Investigation of Verbal Working Memory in Adolescents with Specific Language Impairment

    ERIC Educational Resources Information Center

    Weismer, Susan Ellis; Plante, Elena; Jones, Maura; Tomblin, Bruce J.

    2005-01-01

    This study used neuroimaging and behavioral techniques to examine the claim that processing capacity limitations underlie specific language impairment (SLI). Functional magnetic resonance imaging (fMRI) was used to investigate verbal working memory in adolescents with SLI and normal language (NL) controls. The experimental task involved a modified…

  1. Hyperpolarized functional magnetic resonance of murine skeletal muscle enabled by multiple tracer-paradigm synchronizations.

    PubMed

    Leftin, Avigdor; Roussel, Tangi; Frydman, Lucio

    2014-01-01

    Measuring metabolism's time- and space-dependent responses upon stimulation lies at the core of functional magnetic resonance imaging. While focusing on water's sole resonance, further insight could arise from monitoring the temporal responses arising from the metabolites themselves, in what is known as functional magnetic resonance spectroscopy. Performing these measurements in real time, however, is severely challenged by the short functional timescales and low concentrations of natural metabolites. Dissolution dynamic nuclear polarization is an emerging technique that can potentially alleviate this, as it provides a massive sensitivity enhancement allowing one to probe low-concentration tracers and products in a single-scan. Still, conventional implementations of this hyperpolarization approach are not immediately amenable to the repeated acquisitions needed in real-time functional settings. This work proposes a strategy for functional magnetic resonance of hyperpolarized metabolites that bypasses this limitation, and enables the observation of real-time metabolic changes through the synchronization of stimuli-triggered, multiple-bolus injections of the metabolic tracer 13C1-pyruvate. This new approach is demonstrated with paradigms tailored to reveal in vivo thresholds of murine hind-limb skeletal muscle activation, involving the conversion of 13C1-pyruvate to 13C1-lactate and 13C1-alanine. These functional hind-limb studies revealed that graded skeletal muscle stimulation causes commensurate increases in glycolytic metabolism in a frequency- and amplitude-dependent fashion, that can be monitored on the seconds/minutes timescale using dissolution dynamic nuclear polarization. Spectroscopic imaging further allowed the in vivo visualization of uptake, transformation and distribution of the tracer and products, in fast-twitch glycolytic and in slow-twitch oxidative muscle fiber groups. While these studies open vistas in time and sensitivity for metabolic

  2. Hyperpolarized Functional Magnetic Resonance of Murine Skeletal Muscle Enabled by Multiple Tracer-Paradigm Synchronizations

    PubMed Central

    Leftin, Avigdor; Roussel, Tangi; Frydman, Lucio

    2014-01-01

    Measuring metabolism's time- and space-dependent responses upon stimulation lies at the core of functional magnetic resonance imaging. While focusing on water's sole resonance, further insight could arise from monitoring the temporal responses arising from the metabolites themselves, in what is known as functional magnetic resonance spectroscopy. Performing these measurements in real time, however, is severely challenged by the short functional timescales and low concentrations of natural metabolites. Dissolution dynamic nuclear polarization is an emerging technique that can potentially alleviate this, as it provides a massive sensitivity enhancement allowing one to probe low-concentration tracers and products in a single-scan. Still, conventional implementations of this hyperpolarization approach are not immediately amenable to the repeated acquisitions needed in real-time functional settings. This work proposes a strategy for functional magnetic resonance of hyperpolarized metabolites that bypasses this limitation, and enables the observation of real-time metabolic changes through the synchronization of stimuli-triggered, multiple-bolus injections of the metabolic tracer 13C1-pyruvate. This new approach is demonstrated with paradigms tailored to reveal in vivo thresholds of murine hind-limb skeletal muscle activation, involving the conversion of 13C1-pyruvate to 13C1-lactate and 13C1-alanine. These functional hind-limb studies revealed that graded skeletal muscle stimulation causes commensurate increases in glycolytic metabolism in a frequency- and amplitude-dependent fashion, that can be monitored on the seconds/minutes timescale using dissolution dynamic nuclear polarization. Spectroscopic imaging further allowed the in vivo visualization of uptake, transformation and distribution of the tracer and products, in fast-twitch glycolytic and in slow-twitch oxidative muscle fiber groups. While these studies open vistas in time and sensitivity for metabolic

  3. Modelling of heat assisted magnetic recording with the Landau-Lifshitz-Bloch equation and Brillouin functions

    NASA Astrophysics Data System (ADS)

    Greaves, Simon John; Muraoka, Hiroaki; Kanai, Yasushi

    2015-05-01

    Brillouin functions were used to model the temperature dependence of magnetisation in media for heat assisted magnetic recording. Although dHk/dT was higher when Brillouin functions with J = 0.5 or J = 1 were used, an earlier onset of the linear reversal mode led to a drop in dHc/dT near to Tc, resulting in wider written bits. Tracks written with a higher thermal gradient were also wider when J was small and had lower SNR.

  4. Resting state functional connectivity magnetic resonance imaging integrated with intraoperative neuronavigation for functional mapping after aborted awake craniotomy

    PubMed Central

    Batra, Prag; Bandt, S. Kathleen; Leuthardt, Eric C.

    2016-01-01

    Background: Awake craniotomy is currently the gold standard for aggressive tumor resections in eloquent cortex. However, a significant subset of patients is unable to tolerate this procedure, particularly the very young or old or those with psychiatric comorbidities, cardiopulmonary comorbidities, or obesity, among other conditions. In these cases, typical alternative procedures include biopsy alone or subtotal resection, both of which are associated with diminished surgical outcomes. Case Description: Here, we report the successful use of a preoperatively obtained resting state functional connectivity magnetic resonance imaging (MRI) integrated with intraoperative neuronavigation software in order to perform functional cortical mapping in the setting of an aborted awake craniotomy due to loss of airway. Conclusion: Resting state functional connectivity MRI integrated with intraoperative neuronavigation software can provide an alternative option for functional cortical mapping in the setting of an aborted awake craniotomy. PMID:26958419

  5. Stationary electron velocity distribution function in crossed electric and magnetic fields with collisions

    SciTech Connect

    Shagayda, Andrey

    2012-08-15

    Analytical studies and numerical simulations show that the electron velocity distribution function in a Hall thruster discharge with crossed electric and magnetic fields is not Maxwellian. This is due to the fact that the mean free path between collisions is greater than both the Larmor radius and the characteristic dimensions of the discharge channel. However in numerical models of Hall thrusters, a hydrodynamic approach is often used to describe the electron dynamics, because discharge simulation in a fully kinetic approach requires large computing resources and is time consuming. A more accurate modeling of the electron flow in the hydrodynamic approximation requires taking into account the non-Maxwellian character of the distribution function and finding its moments, an approach that reflects the properties of electrons drifting in crossed electric and magnetic fields better than the commonly used Euler or Navier-Stokes approximations. In the present paper, an expression for the electron velocity distribution function in rarefied spatially homogeneous stationary plasma with crossed electric and magnetic fields and predominance of collisions with heavy particles is derived in the relaxation approximation. The main moments of the distribution function including longitudinal and transversal temperatures, the components of the viscous stress tensor, and of the heat flux vector are calculated. Distinctive features of the hydrodynamic description of electrons with a strongly non-equilibrium distribution function and the prospects for further development of the proposed approach for calculating the distribution function in spatially inhomogeneous plasma are discussed.

  6. Lysophosphatidic acid induces chemotaxis in MC3T3-E1 osteoblastic cells.

    PubMed

    Masiello, Lisa M; Fotos, Joseph S; Galileo, Deni S; Karin, Norman J

    2006-07-01

    Lysophosphatidic acid (LPA) is a bioactive lipid that has pleiotropic effects on a variety of cell types and enhances the migration of endothelial and cancer cells, but it is not known if this lipid can alter osteoblast motility. We performed transwell migration assays using MC3T3-E1 osteoblastic cells and found LPA to be a potent chemotactic agent. Quantitative time-lapse video analysis of osteoblast migration after wounds were introduced into cell monolayers indicated that LPA stimulated both migration velocity and the average migration distance per cell. LPA also elicited substantial changes in cell shape and actin cytoskeletal structure; lipid-treated cells contained fewer stress fibers and displayed long membrane processes that were enriched in F-actin. Quantitative RT-PCR analysis showed that MC3T3-E1 cells express all four known LPA-specific G-protein-coupled receptors (LPA1-LPA4) with a relative mRNA abundance of LPA1>LPA4>LPA2>LPA3. LPA-induced changes in osteoblast motility and morphology were antagonized by both pertussis toxin and Ki16425, a subtype-specific blocker of LPA1 and LPA3 receptor function. Cell migration in many cell types is linked to changes in intracellular Ca2+. Ki16425 also inhibited LPA-induced Ca2+ signaling in a dose-dependent manner, suggesting a link between LPA-induced Ca2+ transients and osteoblast chemotaxis. Our data show that LPA stimulates MC3T3-E1 osteoblast motility via a mechanism that is linked primarily to the G-protein-coupled receptor LPA1. PMID:16487757

  7. Lysophosphatidic acid induces chemotaxis in MC3T3-E1 osteoblastic cells

    SciTech Connect

    Masiello, Lisa M.; Fotos, Joseph S.; Galileo, Deni S.; Karin, Norm J.

    2006-07-01

    Lysophosphatidic acid (LPA) is a bioactive lipid that has pleiotropic effects on a variety of cell types and enhances the migration of endothelial and cancer cells, but it is not known if this lipid can alter osteoblast motility. We performed transwell migration assays using MC3T3-E1 osteoblastic cells and found LPA to be a potent chemotactic agent. Quantitative time-lapse video analysis of osteoblast migration after wounds were introduced into cell monolayers indicated that LPA stimulated both migration velocity and the average migration distance per cell. LPA also elicited substantial changes in cell shape and actin cytoskeletal structure; lipid-treated cells contained fewer stress fibers and displayed long membrane processes that were enriched in F-actin. Quantitative RT-PCR analysis showed that MC3T3-E1 cells express all four known LPA-specific G protein-coupled receptors (LPA1-LPA4) with a relative mRNA abundance of LPA1 > LPA4 > LPA2 >> LPA3. LPA-induced changes in osteoblast motility and morphology were antagonized by both pertussis toxin and Ki16425, a subtype-specific blocker of LPA1 and LPA3 receptor function. Cell migration in many cell types is linked to changes in intracellular Ca2+. Ki16425 also inhibited LPA-induced Ca2+ signaling in a dose-dependent manner, suggesting a link between LPA-induced Ca2+ transients and osteoblast chemotaxis. Our data show that LPA stimulates MC3T3-E1 osteoblast motility via a mechanism that is linked primarily to the G protein-coupled receptor LPA1.

  8. 26 CFR 54.9802-3T - Additional requirements prohibiting discrimination based on genetic information (temporary).

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 26 Internal Revenue 17 2014-04-01 2014-04-01 false Additional requirements prohibiting discrimination based on genetic information (temporary). 54.9802-3T Section 54.9802-3T Internal Revenue INTERNAL REVENUE SERVICE, DEPARTMENT OF THE TREASURY (CONTINUED) MISCELLANEOUS EXCISE TAXES (CONTINUED) PENSION EXCISE TAXES § 54.9802-3T...

  9. 26 CFR 54.9802-3T - Additional requirements prohibiting discrimination based on genetic information (temporary).

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 26 Internal Revenue 17 2012-04-01 2012-04-01 false Additional requirements prohibiting discrimination based on genetic information (temporary). 54.9802-3T Section 54.9802-3T Internal Revenue INTERNAL REVENUE SERVICE, DEPARTMENT OF THE TREASURY (CONTINUED) MISCELLANEOUS EXCISE TAXES (CONTINUED) PENSION EXCISE TAXES § 54.9802-3T...

  10. 26 CFR 54.9802-3T - Additional requirements prohibiting discrimination based on genetic information (temporary).

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 26 Internal Revenue 17 2013-04-01 2013-04-01 false Additional requirements prohibiting discrimination based on genetic information (temporary). 54.9802-3T Section 54.9802-3T Internal Revenue INTERNAL REVENUE SERVICE, DEPARTMENT OF THE TREASURY (CONTINUED) MISCELLANEOUS EXCISE TAXES (CONTINUED) PENSION EXCISE TAXES § 54.9802-3T...

  11. 26 CFR 1.1471-3T - Identification of payee (temporary).

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 26 Internal Revenue 12 2014-04-01 2014-04-01 false Identification of payee (temporary). 1.1471-3T Section 1.1471-3T Internal Revenue INTERNAL REVENUE SERVICE, DEPARTMENT OF THE TREASURY (CONTINUED) INCOME TAX (CONTINUED) INCOME TAXES (CONTINUED) Information Reporting by Foreign Financial Institutions § 1.1471-3T Identification of payee...

  12. 49 CFR 178.45 - Specification 3T seamless steel cylinder.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 49 Transportation 3 2011-10-01 2011-10-01 false Specification 3T seamless steel cylinder. 178.45... PACKAGINGS Specifications for Cylinders § 178.45 Specification 3T seamless steel cylinder. (a) Type, size, and service pressure. A DOT 3T cylinder is a seamless steel cylinder with a minimum water capacity...

  13. 49 CFR 178.45 - Specification 3T seamless steel cylinder.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 49 Transportation 3 2013-10-01 2013-10-01 false Specification 3T seamless steel cylinder. 178.45... PACKAGINGS Specifications for Cylinders § 178.45 Specification 3T seamless steel cylinder. (a) Type, size, and service pressure. A DOT 3T cylinder is a seamless steel cylinder with a minimum water capacity...

  14. 49 CFR 178.45 - Specification 3T seamless steel cylinder.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 49 Transportation 3 2014-10-01 2014-10-01 false Specification 3T seamless steel cylinder. 178.45... PACKAGINGS Specifications for Cylinders § 178.45 Specification 3T seamless steel cylinder. (a) Type, size, and service pressure. A DOT 3T cylinder is a seamless steel cylinder with a minimum water capacity...

  15. 49 CFR 178.45 - Specification 3T seamless steel cylinder.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 49 Transportation 3 2012-10-01 2012-10-01 false Specification 3T seamless steel cylinder. 178.45... PACKAGINGS Specifications for Cylinders § 178.45 Specification 3T seamless steel cylinder. (a) Type, size, and service pressure. A DOT 3T cylinder is a seamless steel cylinder with a minimum water capacity...

  16. 26 CFR 1.892-3T - Income of foreign governments (temporary regulations).

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 26 Internal Revenue 9 2011-04-01 2011-04-01 false Income of foreign governments (temporary regulations). 1.892-3T Section 1.892-3T Internal Revenue INTERNAL REVENUE SERVICE, DEPARTMENT OF THE TREASURY (CONTINUED) INCOME TAX (CONTINUED) INCOME TAXES (CONTINUED) Miscellaneous Provisions § 1.892-3T Income of foreign governments...

  17. 26 CFR 1.702-3T - 4-Year spread (temporary).

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 26 Internal Revenue 8 2011-04-01 2011-04-01 false 4-Year spread (temporary). 1.702-3T Section 1.702-3T Internal Revenue INTERNAL REVENUE SERVICE, DEPARTMENT OF THE TREASURY (CONTINUED) INCOME TAX (CONTINUED) INCOME TAXES (CONTINUED) Partners and Partnerships § 1.702-3T 4-Year spread (temporary). (a) Applicability. This section applies to...

  18. 26 CFR 1.25-3T - Qualified mortgage credit certificate (Temporary).

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 26 Internal Revenue 1 2012-04-01 2012-04-01 false Qualified mortgage credit certificate (Temporary). 1.25-3T Section 1.25-3T Internal Revenue INTERNAL REVENUE SERVICE, DEPARTMENT OF THE TREASURY INCOME TAX INCOME TAXES Changes in Rates During A Taxable Year § 1.25-3T Qualified mortgage credit certificate (Temporary). (a) Definition of...

  19. 26 CFR 1.108(i)-3T - Rules for the deduction of OID (temporary).

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ....108(i)-3T Section 1.108(i)-3T Internal Revenue INTERNAL REVENUE SERVICE, DEPARTMENT OF THE TREASURY....108(i)-3T Rules for the deduction of OID (temporary). (a) Deemed debt-for-debt exchanges—(1) In general. For purposes of section 108(i)(2) (relating to deferred OID deductions that arise in certain...

  20. 26 CFR 1.103(n)-3T - Private activity bond limit (temporary).

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 26 Internal Revenue 2 2010-04-01 2010-04-01 false Private activity bond limit (temporary). 1.103(n)-3T Section 1.103(n)-3T Internal Revenue INTERNAL REVENUE SERVICE, DEPARTMENT OF THE TREASURY....103(n)-3T Private activity bond limit (temporary). Q-1: What is the “State ceiling”? A-1: In...

  1. 26 CFR 1.103(n)-3T - Private activity bond limit (temporary).

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 26 Internal Revenue 2 2011-04-01 2011-04-01 false Private activity bond limit (temporary). 1.103(n)-3T Section 1.103(n)-3T Internal Revenue INTERNAL REVENUE SERVICE, DEPARTMENT OF THE TREASURY....103(n)-3T Private activity bond limit (temporary). Q-1: What is the “State ceiling”? A-1: In...

  2. 26 CFR 1.103(n)-3T - Private activity bond limit (temporary).

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 26 Internal Revenue 2 2013-04-01 2013-04-01 false Private activity bond limit (temporary). 1.103(n)-3T Section 1.103(n)-3T Internal Revenue INTERNAL REVENUE SERVICE, DEPARTMENT OF THE TREASURY....103(n)-3T Private activity bond limit (temporary). Q-1: What is the “State ceiling”? A-1: In...

  3. 26 CFR 1.103(n)-3T - Private activity bond limit (temporary).

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 26 Internal Revenue 2 2014-04-01 2014-04-01 false Private activity bond limit (temporary). 1.103(n)-3T Section 1.103(n)-3T Internal Revenue INTERNAL REVENUE SERVICE, DEPARTMENT OF THE TREASURY....103(n)-3T Private activity bond limit (temporary). Q-1: What is the “State ceiling”? A-1: In...

  4. 26 CFR 1.103(n)-3T - Private activity bond limit (temporary).

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 26 Internal Revenue 2 2012-04-01 2012-04-01 false Private activity bond limit (temporary). 1.103(n)-3T Section 1.103(n)-3T Internal Revenue INTERNAL REVENUE SERVICE, DEPARTMENT OF THE TREASURY....103(n)-3T Private activity bond limit (temporary). Q-1: What is the “State ceiling”? A-1: In...

  5. 26 CFR 1.921-3T - Temporary regulations; Foreign sales corporation general rules.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 26 Internal Revenue 10 2010-04-01 2010-04-01 false Temporary regulations; Foreign sales corporation general rules. 1.921-3T Section 1.921-3T Internal Revenue INTERNAL REVENUE SERVICE, DEPARTMENT OF THE TREASURY (CONTINUED) INCOME TAX (CONTINUED) INCOME TAXES Earned Income of Citizens of United States § 1.921-3T Temporary regulations;...

  6. 26 CFR 1.132-3T - Qualified employee discount-1985 through 1988 (temporary).

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... (temporary). 1.132-3T Section 1.132-3T Internal Revenue INTERNAL REVENUE SERVICE, DEPARTMENT OF THE TREASURY (CONTINUED) INCOME TAX (CONTINUED) INCOME TAXES (CONTINUED) Items Specifically Excluded from Gross Income § 1.132-3T Qualified employee discount—1985 through 1988 (temporary). (a) In general—(1) Definition....

  7. 26 CFR 1.132-3T - Qualified employee discount-1985 through 1988 (temporary).

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... (temporary). 1.132-3T Section 1.132-3T Internal Revenue INTERNAL REVENUE SERVICE, DEPARTMENT OF THE TREASURY (CONTINUED) INCOME TAX (CONTINUED) INCOME TAXES (CONTINUED) Items Specifically Excluded from Gross Income § 1.132-3T Qualified employee discount—1985 through 1988 (temporary). (a) In general—(1) Definition....

  8. A multi-functional testing instrument for heat assisted magnetic recording media

    SciTech Connect

    Yang, H. Z. Chen, Y. J.; Leong, S. H.; An, C. W.; Ye, K. D.; Hu, J. F.; Yin, M. J.

    2014-05-07

    With recent developments in heat assisted magnetic recording (HAMR), characterization of HAMR media is becoming very important. We present a multi-functional instrument for testing HAMR media, which integrates HAMR writing, reading, and a micro-magneto-optic Kerr effect (μ-MOKE) testing function. A potential application of the present instrument is to make temperature dependent magnetic property measurement using a pump-probe configuration. In the measurement, the media is heated up by a heating (intense) beam while a testing (weak) beam is overlapped with the heating beam for MOKE measurement. By heating the media with different heating beam power, magnetic measurements by MOKE at different temperatures can be performed. Compared to traditional existing tools such as the vibrating sample magnetometer, the present instrument provides localized and efficient heating at the measurement spot. The integration of HAMR writing and μ-MOKE system can also facilitate a localized full investigation of the magnetic media by potential correlation of HAMR head independent write/read performance to localized magnetic properties.

  9. Magnetic assembly of transparent and conducting graphene-based functional composites.

    PubMed

    Le Ferrand, Hortense; Bolisetty, Sreenath; Demirörs, Ahmet F; Libanori, Rafael; Studart, André R; Mezzenga, Raffaele

    2016-01-01

    Innovative methods producing transparent and flexible electrodes are highly sought in modern optoelectronic applications to replace metal oxides, but available solutions suffer from drawbacks such as brittleness, unaffordability and inadequate processability. Here we propose a general, simple strategy to produce hierarchical composites of functionalized graphene in polymeric matrices, exhibiting transparency and electron conductivity. These are obtained through protein-assisted functionalization of graphene with magnetic nanoparticles, followed by magnetic-directed assembly of the graphene within polymeric matrices undergoing sol-gel transitions. By applying rotating magnetic fields or magnetic moulds, both graphene orientation and distribution can be controlled within the composite. Importantly, by using magnetic virtual moulds of predefined meshes, graphene assembly is directed into double-percolating networks, reducing the percolation threshold and enabling combined optical transparency and electrical conductivity not accessible in single-network materials. The resulting composites open new possibilities on the quest of transparent electrodes for photovoltaics, organic light-emitting diodes and stretchable optoelectronic devices. PMID:27354243

  10. Phonon and magnetic structure in δ-plutonium from density-functional theory

    DOE PAGESBeta

    Söderlind, Per; Zhou, F.; Landa, A.; Klepeis, J. E.

    2015-10-30

    We present phonon properties of plutonium metal obtained from a combination of density-functional-theory (DFT) electronic structure and the recently developed compressive sensing lattice dynamics (CSLD). The CSLD model is here trained on DFT total energies of several hundreds of quasi-random atomic configurations for best possible accuracy of the phonon properties. The calculated phonon dispersions compare better with experiment than earlier results obtained from dynamical mean-field theory. The density-functional model of the electronic structure consists of disordered magnetic moments with all relativistic effects and explicit orbital-orbital correlations. The magnetic disorder is approximated in two ways: (i) a special quasi-random structure andmore » (ii) the disordered-local-moment (DLM) method within the coherent potential approximation. Magnetism in plutonium has been debated intensely, However, the present magnetic approach for plutonium is validated by the close agreement between the predicted magnetic form factor and that of recent neutron-scattering experiments.« less

  11. Magnetic assembly of transparent and conducting graphene-based functional composites

    PubMed Central

    Le Ferrand, Hortense; Bolisetty, Sreenath; Demirörs, Ahmet F.; Libanori, Rafael; Studart, André R.; Mezzenga, Raffaele

    2016-01-01

    Innovative methods producing transparent and flexible electrodes are highly sought in modern optoelectronic applications to replace metal oxides, but available solutions suffer from drawbacks such as brittleness, unaffordability and inadequate processability. Here we propose a general, simple strategy to produce hierarchical composites of functionalized graphene in polymeric matrices, exhibiting transparency and electron conductivity. These are obtained through protein-assisted functionalization of graphene with magnetic nanoparticles, followed by magnetic-directed assembly of the graphene within polymeric matrices undergoing sol–gel transitions. By applying rotating magnetic fields or magnetic moulds, both graphene orientation and distribution can be controlled within the composite. Importantly, by using magnetic virtual moulds of predefined meshes, graphene assembly is directed into double-percolating networks, reducing the percolation threshold and enabling combined optical transparency and electrical conductivity not accessible in single-network materials. The resulting composites open new possibilities on the quest of transparent electrodes for photovoltaics, organic light-emitting diodes and stretchable optoelectronic devices. PMID:27354243

  12. Investigation of the Magnetic Behavior in Fe3O4 Ferrofluid Functionalized by Carapa Guianensis Oil

    NASA Astrophysics Data System (ADS)

    López, Jorge Luis; Rodriguez, Anselmo Fortunato Ruiz; de Jesus Nascimento Pontes, Maria; de Morais, Paulo Cesar; de Azevedo, Ricardo Bentes; Pfannes, Hans Dieter; Dias Filho, José Higino

    2010-12-01

    A ferrofluid based on Fe3O4 has been synthesized using the condensation method by coprecipitating aqueous solutions of FeSO4 and FeCl3 mixtures in NH4OH and treated further in order to obtain colloidal sols by creating a charge density on their surface and functionalized by carapa guianensis (andiroba oil). Aqueous sample with an average particle diameter ˜7 nm were studied by Mössbauer spectroscopy and dc magnetization measurements in the range of 4.2-250 K. The saturation magnetization (Ms) at 4.2 K was determined from M vs 1/H plots by extrapolating the value of magnetizations to infinite fields, to 5.6 emu/g and coercivity to 344 Oe. The low saturation magnetization value was attributed to spin noncollinearity predominantly at the surface. From the magnetization measurements a magnetic anisotropy energy constant (K) of 1×104 J/m3 was calculated. Fe3O4 spectra at room temperature showed a singlet due to superparamagnetic relaxation and a sextet at low temperature.

  13. SUPERCONDUCTING COMBINED FUNCTION MAGNET SYSTEM FOR J-PARC NEUTRINO EXPERIMENT.

    SciTech Connect

    OGITSU, T.; AJIMA, Y.; ANERELLA, M.; ESCALLIER, J.; GANETIS, G.; GUPTA, R.; HAGEDOM, D.; HARRISON, M.; HIGASHI, N.; IWAMOTO, Y.; ICHIKAWA, A.; JAIN, A.; KIMURA, N.; KOBAYASHI, T.; MAKIDA, Y.; MURATORE, J.; NAKAMOTO, T.; OHHATA, H.; TAKASAKI, N.; TANAKA, K.; TERASHIMA, A.; YAMOMOTO, A.; OBANA, T.; PARKER, B.; WANDERER, P.

    2004-10-03

    The J-PARC Neutrino Experiment, the construction of which starts in JFY 2004, will use a superconducting magnet system for its primary proton beam line. The system, which bends the 50 GeV 0.75 MW proton beam by about 80 degrees, consists of 28 superconducting combined function magnets. The magnets utilize single layer left/right asymmetric coils that generate a dipole field of 2.6 T and a quadrupole field of 18.6 T/m with the operation current of about 7.35 kA. The system also contains a few conduction cooled superconducting corrector magnets that serve as vertical and horizontal steering magnets. All the magnets are designed to provide a physical beam aperture of 130 mm in order to achieve a large beam acceptance. Extensive care is also required to achieve safe operation with the high power proton beam. The paper summarizes the system design as well as some safety analysis results.

  14. Unconventional electronic and magnetic functions of nanographene-based host-guest systems.

    PubMed

    Enoki, Toshiaki; Takai, Kazuyuki

    2008-08-01

    Nanographene has a unique electronic structure which critically depends on the shape of its edge. A zigzag-edged nanographene sheet has a non-bonding pi-electron state (edge state), yielding a strong spin magnetism for edge-state localized spins, in spite of the absence of such a state in an armchair-edged nanographene sheet. Nanographite (stacked nanographene sheets)-network-based nanoporous carbon is employed as the host material to build unconventional magnetic systems based on the host-guest interaction. The physisorption of various guest materials can cause a reversible low-spin/high-spin magnetic switching phenomenon, whose feature varies depending on the type of guest species. The edge-state spins are utilized as a probe to detect a huge condensation of helium atoms in the nanopores. The giant magnetoresistance of the nanographite network is controlled by the physisorption of magnetic oxygen molecules. The confinement of potassium clusters in the nanopores surrounded by nanographite domains yields an interesting nanomagnetic state. Nanographene/nanographite is an intriguing pi-electron-based nanocarbon material with the potential of producing unconventional magnetic structures that cannot be obtained using bulk graphite. The processability of nanographene/nanographite is expected to give a variety of magnetic functions for spintronic applications. PMID:18629396

  15. Development of Small-sized Fluid Control Valve with Self-holding Function Using Permanent Magnet

    NASA Astrophysics Data System (ADS)

    Akagi, Tetsuya; Dohta, Shujiro; Ueda, Hirofumi

    Recently, force feedback devices in virtual reality and power assisted nursing care systems have received much attention and active research. In such a control system, an actuator and a driving device such as a control valve are mounted on the human body. In this condition, the size and weight of the control valve become serious problems. At the same time, the valve should be operated with lower energy consumption because of using a limited electrical power. The typical electro magnetic solenoid valve drives its spool using a larger solenoid to open the valve. The complex construction of the valve for sealing makes its miniaturization and the fabrication of a low cost valve more difficult. In addition, the solenoid in the valve consumes more electrical power while the valve is kept opening. The purpose of our study is to develop a small-sized, lightweight, lower energy consumption and flexible control valve that can be safe enough to mount on the human body at a lower cost. In our pervious study, we proposed and tested the control valve that can open using a vibration motor. In this study, we propose and test a new type of fluid control valve with a self-holding function. The new valve uses a permanent magnet ball. It has a cylindrical magnet and two solenoids. The self-holding function of the valve is done as follows. When one side of the solenoid is stimulated by the current momentarily, the solenoid gives a repulsive force to the cylindrical magnet. The magnet moves toward the opposite side of the solenoid and is attracted to the iron core. Then, the magnet ball moves toward the cylindrical magnet and opens the orifice. The valve can keep open without electrical energy. As a result, the valve with the extremely lower energy consumption can be developed.

  16. Kibizu concentrated liquid suppresses the accumulation of lipid droplets in 3T3-L1 cells.

    PubMed

    Inoue, Chisato; Kozaki, Tomomi; Morita, Yukiko; Shirouchi, Bungo; Fukami, Katsuya; Shimizu, Kuniyoshi; Sato, Masao; Katakura, Yoshinori

    2015-08-01

    Adipocyte size is closely related to the occurrence of diabetes, metabolic syndrome, and insulin resistance. Thus, researchers are searching for active substances that function to reduce adipocyte size. In the present study, we focused on sugar cane vinegar, Kibizu, and evaluated the function of Kibizu to reduce adipocyte size by using an in vitro model system, because people in Amami Oshima famous for longevity regularly consume Kibizu. Results showed that Kibizu treatment significantly reduced the size and number of lipid droplets in 3T3-L1 cells, relative to treatment with Kurozu, another traditional vinegar. Results of an extraction experiment suggest that the active components in Kibizu are lipophilic and hydrophobic. In addition, an in vivo experiment on rats treated with Kibizu showed that the active components were contained in large vein blood. Results of an additional in vivo experiment suggest that metabolites generated by Kibizu-treated rats are primarily contained or modified specifically in the large vein blood. PMID:25672941

  17. Fabrication and hyperthermia effect of magnetic functional fluids based on amorphous particles

    NASA Astrophysics Data System (ADS)

    Yang, Chuncheng; Bian, Xiufang; Qin, Jingyu; Guo, Tongxiao; Zhao, Shuchun

    2015-03-01

    An experimental study conducted on the preparation and hyperthermia effect of magnetic functional fluids based on Fe73.5Nb3Cu1Si13.5B9 amorphous particles, CoFe2O4 nanoparticles and Fe3O4 nanoparticles dispersed in water is presented. Scanning electron microscopy, X-ray diffraction, differential scanning calorimetry and vibrating sample magnetometer methods have been used to characterize the morphology, structure and magnetic property of the amorphous particles. It is disclosed that the Fe73.5Nb3Cu1Si13.5B9 particles are still amorphous after being milled for 48 h. Moreover, the saturation magnetization of metallic glass particles is approximately 75% and 50% larger than that of CoFe2O4 nanoparticles and Fe3O4 nanoparticles, respectively. The hyperthermia experiment results show that when alternating electrical current is 150 A, the temperature of the functional fluids based on amorphous particles could rise to 33 °C in 1500 s. When the current is 300 A, the final stable temperature could reach to 60 °C. This study demonstrates that the Fe73.5Nb3Cu1Si13.5B9 magnetic functional fluids may have potential on biomedical applications.

  18. Magnetism of C adatoms on BN nanostructures: implications for functional nanodevices.

    PubMed

    Li, Jia; Zhou, Gang; Chen, Ying; Gu, Bing-Lin; Duan, Wenhui

    2009-02-11

    Spin-polarized density functional calculations reveal that magnetism can be induced by carbon adatoms on boron nitride nanotubes (BNNTs) and BN hexagonal sheets. As a result of the localization of impurity states, these hybrid sp-electron systems are spin-polarized, with a local magnetic moment of 2.0 mu(B) per C adatom regardless of the tube diameter and the bonding between the C atom and the BNNTs/BN sheets. An analysis of orbital hybridization indicates that two valence electrons participate in the bonding and the remaining two electrons of the C adatom are confined at the adsorption site and contribute to the magnetism accordingly. The effective interaction distance between the C-induced magnetic moments is evaluated. In terms of the diffusion barrier and the adsorption energy of C adatoms on the BN nanotubes/sheets, a fabrication method for BN-C-based functional nanodevices is proposed, and a series of virtual building blocks for functional devices are illustrated. PMID:19154109

  19. Pre-clinical functional Magnetic Resonance Imaging Part II: The heart.

    PubMed

    Meßner, Nadja M; Zöllner, Frank G; Kalayciyan, Raffi; Schad, Lothar R

    2014-12-01

    One third of all deaths worldwide in 2008 were caused by cardiovascular diseases (CVD), and the incidence of CVD related deaths rises ever more. Thus, improved imaging techniques and modalities are needed for the evaluation of cardiac morphology and function. Cardiac magnetic resonance imaging (CMRI) is a minimally invasive technique that is increasingly important due to its high spatial and temporal resolution, its high soft tissue contrast and its ability of functional and quantitative imaging. It is widely accepted as the gold standard of cardiac functional analysis. In the short period of small animal MRI, remarkable progress has been achieved concerning new, fast imaging schemes as well as purpose-built equipment. Dedicated small animal scanners allow for tapping the full potential of recently developed animal models of cardiac disease. In this paper, we review state-of-the-art cardiac magnetic resonance imaging techniques and applications in small animals at ultra-high fields (UHF). PMID:25023418

  20. Iron oxide magnetic nanoparticles with versatile surface functions based on dopamine anchors.

    PubMed

    Mazur, Mykola; Barras, Alexandre; Kuncser, Victor; Galatanu, Andrei; Zaitzev, Vladimir; Turcheniuk, Kostiantyn V; Woisel, Patrice; Lyskawa, Joel; Laure, William; Siriwardena, Aloysius; Boukherroub, Rabah; Szunerits, Sabine

    2013-04-01

    The synthesis of multifunctional magnetic nanoparticles (MF-MPs) is one of the most active research areas in advanced materials as their multifunctional surfaces allow conjugation of biological and chemical molecules, thus making it possible to achieve target-specific diagnostic in parallel to therapeutics. We report here a simple strategy to integrate in a one-step reaction several reactive sites onto the particles. The preparation of MF-MPs is based on their simultaneous modification with differently functionalized dopamine derivatives using simple solution chemistry. The formed MF-MPs show comparable magnetic properties to those of naked nanoparticles with almost unaltered particle size of around 25 nm. The different termini, amine, azide and maleimide functions, enable further functionalization of MF-MPs by the grafting-on approach. Michael addition, Cu(i) catalyzed « click » chemistry and amidation reactions are performed on the MF-MPs integrating subsequently 6-(ferrocenyl)-hexanethiol, horseradish peroxidase (HRP) and mannose. PMID:23420060

  1. Iron oxide magnetic nanoparticles with versatile surface functions based on dopamine anchors

    NASA Astrophysics Data System (ADS)

    Mazur, Mykola; Barras, Alexandre; Kuncser, Victor; Galatanu, Andrei; Zaitzev, Vladimir; Turcheniuk, Kostiantyn V.; Woisel, Patrice; Lyskawa, Joel; Laure, William; Siriwardena, Aloysius; Boukherroub, Rabah; Szunerits, Sabine

    2013-03-01

    The synthesis of multifunctional magnetic nanoparticles (MF-MPs) is one of the most active research areas in advanced materials as their multifunctional surfaces allow conjugation of biological and chemical molecules, thus making it possible to achieve target-specific diagnostic in parallel to therapeutics. We report here a simple strategy to integrate in a one-step reaction several reactive sites onto the particles. The preparation of MF-MPs is based on their simultaneous modification with differently functionalized dopamine derivatives using simple solution chemistry. The formed MF-MPs show comparable magnetic properties to those of naked nanoparticles with almost unaltered particle size of around 25 nm. The different termini, amine, azide and maleimide functions, enable further functionalization of MF-MPs by the grafting-on approach. Michael addition, Cu(i) catalyzed « click » chemistry and amidation reactions are performed on the MF-MPs integrating subsequently 6-(ferrocenyl)-hexanethiol, horseradish peroxidase (HRP) and mannose.

  2. Disrupted Brain Functional Network in Internet Addiction Disorder: A Resting-State Functional Magnetic Resonance Imaging Study

    PubMed Central

    Yap, Pew-Thian; Wu, Guorong; Shi, Feng; Price, True; Du, Yasong; Xu, Jianrong; Zhou, Yan; Shen, Dinggang

    2014-01-01

    Internet addiction disorder (IAD) is increasingly recognized as a mental health disorder, particularly among adolescents. The pathogenesis associated with IAD, however, remains unclear. In this study, we aim to explore the encephalic functional characteristics of IAD adolescents at rest using functional magnetic resonance imaging data. We adopted a graph-theoretic approach to investigate possible disruptions of functional connectivity in terms of network properties including small-worldness, efficiency, and nodal centrality on 17 adolescents with IAD and 16 socio-demographically matched healthy controls. False discovery rate-corrected parametric tests were performed to evaluate the statistical significance of group-level network topological differences. In addition, a correlation analysis was performed to assess the relationships between functional connectivity and clinical measures in the IAD group. Our results demonstrate that there is significant disruption in the functional connectome of IAD patients, particularly between regions located in the frontal, occipital, and parietal lobes. The affected connections are long-range and inter-hemispheric connections. Although significant alterations are observed for regional nodal metrics, there is no difference in global network topology between IAD and healthy groups. In addition, correlation analysis demonstrates that the observed regional abnormalities are correlated with the IAD severity and behavioral clinical assessments. Our findings, which are relatively consistent between anatomically and functionally defined atlases, suggest that IAD causes disruptions of functional connectivity and, importantly, that such disruptions might link to behavioral impairments. PMID:25226035

  3. On the spectral expansion of the electric and magnetic dyadic Green's functions in cylindrical harmonics

    NASA Astrophysics Data System (ADS)

    Pearson, L. W.

    1983-04-01

    The expansions of the electric and magnetic dyadic Green's functions are constructed in terms of the solenoidal Hansen vector wave functions in cylindrical coordinates. A static term is shown to arise in the course of conducting the radial spectral integral. This pole term has apparently not been identified in previously published expansions and is similar to recently identified static terms in Cartesian and spherical wave function expansions. The integration in the longitudinal spectral variable is considered, too, and forms which offer two alternative integration paths are constructed.

  4. Green's function theory of orbital magnetic moment of interacting electrons in solids

    NASA Astrophysics Data System (ADS)

    Aryasetiawan, F.; Karlsson, K.; Miyake, T.

    2016-04-01

    A general formula for the orbital magnetic moment of interacting electrons in solids is derived using the many-electron Green's function method. The formula factorizes into two parts, a part that contains the information about the one-particle band structure of the system and a part that contains the effects of exchange and correlations carried by the Green's function. The derived formula provides a convenient yet rigorous means of including the effects of exchange and correlations beyond the commonly used local density approximation of density functional theory.

  5. Direct coprecipitation route to monodisperse dual-functionalized magnetic iron oxide nanocrystals without size selection.

    PubMed

    Li, Zhen; Tan, Bien; Allix, Mathieu; Cooper, Andrew I; Rosseinsky, Matthew J

    2008-02-01

    Water-soluble monodisperse superparamagnetic Fe3O4 nanocrystals decorated with two distinct functional groups are prepared in a single-step procedure by injecting iron precursors into a refluxing aqueous solution of a polymer ligand, trithiol-terminated poly(methacrylic acid) (PMAA-PTTM), bearing both carboxylate and thiol functionalities. The ratio of carboxylic acid groups in the polymer-protecting ligand to the iron precursors plays a key role in determining the particle size and particle size distribution. The surface functionalities of the ligands allow post-synthesis modification of the materials to produce water-soluble fluorescent magnetic nanocrystals. PMID:18213671

  6. A Novel Data-Driven Approach to Preoperative Mapping of Functional Cortex Using Resting-State Functional Magnetic Resonance Imaging

    PubMed Central

    Mitchell, Timothy J.; Hacker, Carl D.; Breshears, Jonathan D.; Szrama, Nick P.; Sharma, Mohit; Bundy, David T.; Pahwa, Mrinal; Corbetta, Maurizio; Snyder, Abraham Z.; Shimony, Joshua S.

    2013-01-01

    BACKGROUND: Recent findings associated with resting-state cortical networks have provided insight into the brain's organizational structure. In addition to their neuroscientific implications, the networks identified by resting-state functional magnetic resonance imaging (rs-fMRI) may prove useful for clinical brain mapping. OBJECTIVE: To demonstrate that a data-driven approach to analyze resting-state networks (RSNs) is useful in identifying regions classically understood to be eloquent cortex as well as other functional networks. METHODS: This study included 6 patients undergoing surgical treatment for intractable epilepsy and 7 patients undergoing tumor resection. rs-fMRI data were obtained before surgery and 7 canonical RSNs were identified by an artificial neural network algorithm. Of these 7, the motor and language networks were then compared with electrocortical stimulation (ECS) as the gold standard in the epilepsy patients. The sensitivity and specificity for identifying these eloquent sites were calculated at varying thresholds, which yielded receiver-operating characteristic (ROC) curves and their associated area under the curve (AUC). RSNs were plotted in the tumor patients to observe RSN distortions in altered anatomy. RESULTS: The algorithm robustly identified all networks in all patients, including those with distorted anatomy. When all ECS-positive sites were considered for motor and language, rs-fMRI had AUCs of 0.80 and 0.64, respectively. When the ECS-positive sites were analyzed pairwise, rs-fMRI had AUCs of 0.89 and 0.76 for motor and language, respectively. CONCLUSION: A data-driven approach to rs-fMRI may be a new and efficient method for preoperative localization of numerous functional brain regions. ABBREVIATIONS: AUC, area under the curve BA, Brodmann area BOLD, blood oxygen level dependent ECS, electrocortical stimulation fMRI, functional magnetic resonance imaging ICA, independent component analysis MLP, multilayer perceptron MP

  7. Poly(L-lactide) crystallization topography directs MC3T3-E1 cells response.

    PubMed

    Li, Wenqiang; Lu, Lu; Jiao, Yanpeng; Zhang, Chaowen; Zhou, Changren

    2016-09-01

    Biomaterial surface topography significantly influences cellular form and function. Using poly(L-lactic acid) films with normal spherulites, banded spherulites, and amorphous surfaces as model substrates, we conducted a systematic assessment of the role for polymer crystallization induced surface morphologies on cell growth and contact guidance. Microscopy and image analysis showed that the MC3T3-E1 cells spread out in a random fashion on the amorphous substrate. At 24 h post-seeding, MC3T3-E1 cells on both types of spherulite surfaces were elongated and aligned along the spherulite radius direction. For the banded spherulite surface with radial stripes and coupling annular grooves, the cell orientation and cell nuclear localization were related to the grooves structure. With increasing time, this orientation preference was weaker. These results demonstrate that the patterning of polymer crystallization structure provide important signals for guiding cells to exhibit characteristic orientation and morphology especially in the early stages of regeneration. PMID:27376548

  8. Polyamine metabolism is involved in adipogenesis of 3T3-L1 cells.

    PubMed

    Ishii, Ikumi; Ikeguchi, Yoshihiko; Mano, Hiroshi; Wada, Masahiro; Pegg, Anthony E; Shirahata, Akira

    2012-02-01

    Polyamines spermidine and spermine are known to be required for mammalian cell proliferation and for embryonic development. Alpha-difluoromethylornithine (DFMO), an inhibitor of ornithine decarboxylase (ODC) a limiting enzyme of polyamine biosynthesis, depleted the cellular polyamines and prevented triglyceride accumulation and differentiation in 3T3-L1 cells. In this study, to explore the function of polyamines in adipogenesis, we examined the effect of polyamine biosynthesis inhibitors on adipocyte differentiation and lipid accumulation of 3T3-L1 cells. The spermidine synthase inhibitor trans-4-methylcyclohexylamine (MCHA) increased spermine/spermidine ratios, whereas the spermine synthase inhibitor N-(3-aminopropyl)-cyclohexylamine (APCHA) decreased the ratios in the cells. MCHA was found to decrease lipid accumulation and GPDH activity during differentiation, while APCHA increased lipid accumulation and GPDH activity indicating the enhancement of differentiation. The polyamine-acetylating enzyme, spermidine/spermine N(1)-acetyltransferase (SSAT) activity was increased within a few hours after stimulus for differentiation, and was found to be elevated by APCHA. In mature adipocytes APCHA decreased lipid accumulation while MCHA had the opposite effect. An acetylpolyamine oxidase and spermine oxidase inhibitor MDL72527 or an antioxidant N-acetylcysteine prevented the promoting effect of APCHA on adipogenesis. These results suggest that not only spermine/spermidine ratios but also polyamine catabolic enzyme activity may contribute to adipogenesis. PMID:21809076

  9. Conventional kinesin KIF5B mediates adiponectin secretion in 3T3-L1 adipocytes.

    PubMed

    Cui, Ju; Pang, Jing; Lin, Ya-Jun; Jiang, Ping; Gong, Huan; Wang, Zai; Li, Jian; Cai, Jian-Ping; Huang, Jian-Dong; Zhang, Tie-Mei

    2016-08-01

    Insulin stimulates adiponectin secretion and glucose transporter type 4 (GLUT4) translocation in adipocyte to regulate metabolism homeostasis. Similar to GLUT4 translocation, intracellular trafficking and release of adiponectin in adipocytes relies on the trans-Golgi network and endosomal system. Recent studies show that the heavy chain of conventional kinesin (KIF5B) mediates GLUT4 translocation in murine 3T3-L1 adipocytes, however, the motor machinery involved in mediating intracellular trafficking and release of adiponectin is unknown. Here, we examined the role of KIF5B in the regulation of adiponectin secretion. The KIF5B level was up-regulated during 3T3-L1 adipogenesis. This increase in cytosolic KIF5B was synchronized with the induction of adiponectin. Endogenous KIF5B and adiponectin were partially colocalized at the peri-nuclear and cytosolic regions. In addition, adiponectin-containing vesicles were co-immunoprecipitated with KIF5B. Knockdown of KIF5B resulted in a marked inhibition of adiponectin secretion and overexpression of KIF5B enhanced adiponectin release, whereas leptin secretion was not affected by changes in KIF5B expression. These data suggest that the secretion of adiponectin, but not leptin, is dependent on functional KIF5B. PMID:27264953

  10. Interhemispheric neuroplasticity following limb deafferentation detected by resting-state functional connectivity magnetic resonance imaging (fcMRI) and functional magnetic resonance imaging (fMRI)

    PubMed Central

    Pawela, Christopher P.; Biswal, Bharat B.; Hudetz, Anthony G.; Li, Rupeng; Jones, Seth R.; Cho, Younghoon R.; Matloub, Hani S.; Hyde, James S.

    2009-01-01

    Functional connectivity magnetic resonance imaging (fcMRI) studies in rat brain show brain reorganization following peripheral nerve injury. Subacute neuroplasticity was observed two weeks following transection of the four major nerves of the brachial plexus. Direct functional magnetic resonance imaging (fMRI) stimulation of the intact radial nerve reveals an activation pattern in the forelimb regions of the sensory and motor cortices that is significantly different from that observed in normal rats. Results of this fMRI experiment were used to determine seed voxel regions for fcMRI analysis. Intrahemispheric connectivities in the sensorimotor forelimb representations in both hemispheres are largely unaffected by deafferentation, whereas substantial disruption of interhemispheric sensorimotor cortical connectivity occurs. In addition, significant intra- and interhemispheric changes in connectivities of thalamic nuclei were found. These are the central findings of the study. They could not have been obtained from fMRI studies alone—both fMRI and fcMRI are needed. The combination provides a general marker for brain plasticity. The rat visual system was studied in the same animals as a control. No neuroplastic changes in connectivities were found in the primary visual cortex upon forelimb deafferentation. Differences were noted in regions responsible for processing multisensory visual-motor information. This incidental discovery is considered to be significant. It may provide insight into phantom limb epiphenomena. PMID:19796693

  11. High glucose induces autophagy of MC3T3-E1 cells via ROS-AKT-mTOR axis.

    PubMed

    Wang, Xiaoju; Feng, Zhengping; Li, Jiling; Chen, Lixue; Tang, Weixue

    2016-07-01

    In the present study, we investigate the function of ROS-AKT-mTOR axis on the apoptosis, proliferation and autophagy of MC3T3-E1 cells, and the proliferation of MC3T3-E1 cells after autophagy inhibition under high glucose conditions. MC3T3-E1 cells cultured in vitro were divided into the following groups: normal control group, N-acetylcysteine (NAC) group, 11.0 mM high glucose group, 11.0 mM high glucose + NAC group, 22.0 mM high glucose group, 22.0 mM high glucose + NAC group, CQ group, 22.0 mM high glucose + CQ group, 3-MA group and 3-MA + 22.0 mM high glucose group. ROS production was measured by DCFH-DA fluorescent probe. Cell proliferation was measured by MTT assay. Cells in different groups were stained with Annexin V-FITC/PI, and then apoptosis rate was detected by flow cytometry. Nucleus morphology was observed under fluorescence microscope after being incubated with Honchest33258. Protein expression was measured using Western blotting and immunofluorescence. Cell apoptosis and proliferation in high glucose group were increased and decreased, respectively, in a dose-dependent manner. Autophagy was significantly induced in high glucose group, even though different concentration of glucose induced autophagy in different stages of autophagy. ROS production in MC3T3-E1 cells was remarkably increased in high glucose group, but not in a dose-dependent manner. NAC, as an antioxidant, reduced ROS production and ameliorated cell apoptosis, proliferation abnormity and autophagy caused by high glucose. Expression of p-AKT and p-mTOR proteins were dramatically decreased in high glucose group, and NAC reversed their expression. In addition, 3-MA, an inhibitor of autophagy, significantly decreased the proliferation of MC3T3-E1 cells. When cocultured with 22.0 mM glucose that induced autophagy, proliferation of MC3T3-E1 cells was not affected compared to 22.0 mM high glucose group. Our present findings reveal that high glucose affects apoptosis

  12. Drug-induced Parkinsonism versus Idiopathic Parkinson Disease: Utility of Nigrosome 1 with 3-T Imaging.

    PubMed

    Sung, Young Hee; Noh, Young; Lee, Jongho; Kim, Eung Yeop

    2016-06-01

    Purpose To explore the utility of nigrosome 1 with 3-T magnetic resonance (MR) imaging to differentiate idiopathic Parkinson disease (IPD) from drug-induced parkinsonism (DIP). Materials and Methods The institutional review board approved this study, and participants gave informed consent. This study enrolled patients with DIP (n = 20) and IPD (n = 29) who underwent N-3-fluoropropyl-2-β-carbomethoxy-3-β-(4-iodophenyl)nortropane ((18)F-FP-CIT) positron emission tomography (PET) and healthy participants (n = 20). All participants underwent 0.5 × 0.5 × 1.0 mm(3) oblique axial three-dimensional multiecho-data image combination imaging to view the nigrosome 1 with 3-T imaging. Two reviewers independently assessed the nigrosome 1 without clinical information. DIP was diagnosed when no abnormality was seen at (18)F-FP-CIT PET. Diagnostic sensitivity, specificity, and accuracy of the nigrosome 1 imaging were evaluated between the IPD and DIP patients and between the IPD patients and healthy participants. Interrater agreement was assessed with Cohen κ. Results Both reviewers agreed in 63 of 69 participants (91.3%) for the presence of any abnormality on either side of the nigrosome 1 (κ = 0.825). Findings in all 29 IPD patients (100%) and three of 20 DIP patients (15%) were rated as abnormal and in 17 of 20 DIP patients (85%) they were interpreted as normal on the basis of imaging of the nitgrosome 1 (sensitivity, 100% (29 of 29); specificity, 85.0% (17 of 20); accuracy, 93.9% (46 of 49) between IPD and DIP patients). Findings in 3 of 20 healthy participants (15.0%) were interpreted as abnormal on the basis of imaging the nigrosome 1 while in the other 17 of 20 healthy participants (85.0%) they were rated as normal (sensitivity, 100% [29 of 29]; specificity, 85.0% [17 of 20]; accuracy, 93.9% [46 of 49] between IPD patients and healthy participants [κ = 0.831]). Conclusion The imaging of nigrosome 1 with 3-T imaging can differentiate DIP from IPD with high accuracy and

  13. In-bore setup and software for 3T MRI-guided transperineal prostate biopsy

    NASA Astrophysics Data System (ADS)

    Tokuda, Junichi; Tuncali, Kemal; Iordachita, Iulian; Song, Sang-Eun; Fedorov, Andriy; Oguro, Sota; Lasso, Andras; Fennessy, Fiona M.; Tempany, Clare M.; Hata, Nobuhiko

    2012-09-01

    MRI-guided prostate biopsy in conventional closed-bore scanners requires transferring the patient outside the bore during needle insertion due to the constrained in-bore space, causing a safety hazard and limiting image feedback. To address this issue, we present our custom-made in-bore setup and software to support MRI-guided transperineal prostate biopsy in a wide-bore 3 T MRI scanner. The setup consists of a specially designed tabletop and a needle-guiding template with a Z-frame that gives a physician access to the perineum of the patient at the imaging position and allows the physician to perform MRI-guided transperineal biopsy without moving the patient out of the scanner. The software and Z-frame allow registration of the template, target planning and biopsy guidance. Initially, we performed phantom experiments to assess the accuracy of template registration and needle placement in a controlled environment. Subsequently, we embarked on our clinical trial (N = 10). The phantom experiments showed that the translational errors of the template registration along the right-left (RP) and anterior-posterior (AP) axes were 1.1 ± 0.8 and 1.4 ± 1.1 mm, respectively, while the rotational errors around the RL, AP and superior-inferior axes were (0.8 ± 1.0)°, (1.7 ± 1.6)° and (0.0 ± 0.0)°, respectively. The 2D root-mean-square (RMS) needle-placement error was 3 mm. The clinical biopsy procedures were safely carried out in all ten clinical cases with a needle-placement error of 5.4 mm (2D RMS). In conclusion, transperineal prostate biopsy in a wide-bore 3T scanner is feasible using our custom-made tabletop setup and software, which supports manual needle placement without moving the patient out of the magnet.

  14. Feasibility Study of Large Combined Function Magnets for the Jefferson Lab 12 GeV Upgrade

    SciTech Connect

    Brindza P. D.; LeRose J. J.; Leung E. M.

    2005-05-01

    The 12 GeV upgrade at Jefferson Lab has identified two new large spectrometers as Physics detectors for the project. The first is a 7.5 Gev/c 35 m-sr. spectrometer that requires a pair of identical Combined Function Superconducting Magnets (CFSM) that can simultaneously produce 1.5 T dipole fields and 4.5 T/m quadrupole fields inside a warm bore of 120 cm. The second is an 11 GeV/c 2 m-sr. spectrometer that requires a CFSM that simultaneously produces a dipole field of 4.0 T and a quadruple field of 3.0 T/m in a 60 cm warm bore. Magnetic designs using TOSCA 3D have been performed to realize the magnetic requirements, provide 3d fields for optics analysis and produce field and force information for the engineering feasibility of the magnets. A two-sector cos(theta)/cos(2theta) design with a low nominal current density, warm bore and warm iron design has been selected and analyzed. These low current densities are consistent with the limits for a cryostable winding. The current paper will summarize the requirement definition of these two magnets. The conceptual design arrived at during the feasibility study involving the choice of conductors, thermal and structural analyses will be presented. A discussion of the manufacturing approach and challenges will be provided.

  15. Electronic and magnetic properties of silicon supported organometallic molecular wires: a density functional theory (DFT) study.

    PubMed

    Liu, Xia; Tan, Yingzi; Li, Xiuling; Wu, Xiaojun; Pei, Yong

    2015-08-28

    The electronic and magnetic properties of transition metal (TM = Sc, Ti, V, Cr and Mn) atom incorporated single and double one-dimensional (1D) styrene molecular wires confined on the hydrogen-terminated Si(100) surface are explored for the first time by means of spin-polarized density functional theory, denoted as Si-[TM(styrene)]. It is unveiled that TM atoms bind asymmetrically to the adjacent phenyl rings, which leads to novel electronic and magnetic properties in stark contrast to the well-studied gas phase TM-benzene molecular wires. Si-[Mn(styrene)]∞ and Si-[Cr(styrene)]∞ single molecular wires (SMWs) are a ferromagnetic semiconductor and half metal, respectively. Creation of H-atom defects on the silicon surface can introduce an impurity metallic band, which leads to novel half-metallic magnetism of a Si-[Mn(styrene)]∞ system. Moreover, double molecular wires (DMWs) containing two identical or hetero SMWs are theoretically designed. The [Mn(styrene)]∞-[Cr(styrene)]∞ DMW exhibits half-metallic magnetism where the spin-up and spin-down channels are contributed by two single molecular wires. Finally, we demonstrate that introducing a TM-defect may significantly affect the electronic structure and magnetic properties of molecular wires. These studies provide new insights into the structure and properties of surface supported 1-D sandwiched molecular wires and may inspire the future experimental synthesis of substrate confined organometallic sandwiched molecular wires. PMID:26219748

  16. Geometric and magnetic properties of Pt clusters supported on graphene: Relativistic density-functional calculations

    NASA Astrophysics Data System (ADS)

    Błoński, Piotr; Hafner, Jürgen

    2011-04-01

    The geometric and magnetic structures of small Ptn clusters (n = 1 - 5) supported on a graphene layer have been investigated using ab initio density functional calculations including spin-orbit coupling. Pt-Pt interactions were found to be much stronger than the Pt-C interactions promoting the binding to the support. As a consequence, the equilibrium structure of the gas-phase clusters is preserved if they are deposited on graphene. However, the clusters bind to graphene only via at most two Pt-C bonds: A Pt2 dumbbell prefers an upright position, the larger clusters are bound to graphene only via one edge of the planar cluster (Pt3 and Pt5) or via two terminal Pt atoms of a bent Pt4 rhombus. Evidently, the strong buckling of the graphene layer induced by the Pt-C bonds prevents the formation of a larger number of cluster-support bonds. As the local spin and orbital magnetic moments are quenched on the Pt atoms forming Pt-C bonds, the magnetic structure of the supported clusters is much more inhomogeneous as in the gas-phase. This leads to noncollinear magnetic structures and a strongly reduced magnetic anisotropy energy.

  17. Ion energy-angle distribution functions at the plasma-material interface in oblique magnetic fields

    SciTech Connect

    Khaziev, Rinat; Curreli, Davide

    2015-04-15

    The ion energy-angle distribution (IEAD) at the wall of a magnetized plasma is of fundamental importance for the determination of the material processes occurring at the plasma-material interface, comprising secondary emissions and material sputtering. Here, we present a numerical characterization of the IEAD at the wall of a weakly collisional magnetized plasma with the magnetic field inclined at an arbitrary angle with respect to the wall. The analysis has been done using two different techniques: (1) a fluid-Monte Carlo method, and (2) particle-in-cell simulations, the former offering a fast but approximate method for the determination of the IEADs, the latter giving a computationally intensive but self-consistent treatment of the plasma behavior from the quasi-neutral region to the material boundary. The two models predict similar IEADs, whose similarities and differences are discussed. Data are presented for magnetic fields inclined at angles from normal to grazing incidence (0°–85°). We show the scaling factors of the average and peak ion energy and trends of the pitch angle at the wall as a function of the magnetic angle, for use in the correlation of fluid plasma models to material models.

  18. Comparison and functionalization study of microemulsion-prepared magnetic iron oxide nanoparticles.

    PubMed

    Okoli, Chuka; Sanchez-Dominguez, Margarita; Boutonnet, Magali; Järås, Sven; Civera, Concepción; Solans, Conxita; Kuttuva, Gunaratna Rajarao

    2012-06-01

    Magnetic iron oxide nanoparticles (MION) for protein binding and separation were obtained from water-in-oil (w/o) and oil-in-water (o/w) microemulsions. Characterization of the prepared nanoparticles have been performed by TEM, XRD, SQUID magnetometry, and BET. Microemulsion-prepared magnetic iron oxide nanoparticles (ME-MION) with sizes ranging from 2 to 10 nm were obtained. Study on the magnetic properties at 300 K shows a large increase of the magnetization ~35 emu/g for w/o-ME-MION with superparamagnetic behavior and nanoscale dimensions in comparison with o/w-ME-MION (10 emu/g) due to larger particle size and anisotropic property. Moringa oleifera coagulation protein (MOCP) bound w/o- and o/w-ME-MION showed an enhanced performance in terms of coagulation activity. A significant interaction between the magnetic nanoparticles and the protein can be described by changes in fluorescence emission spectra. Adsorbed protein from MOCP is still retaining its functionality even after binding to the nanoparticles, thus implying the extension of this technique for various applications. PMID:22578053

  19. Functional magnetic resonance imaging in intact plants--quantitative observation of flow in plant vessels.

    PubMed

    Kuchenbrod, E; Kahler, E; Thürmer, F; Deichmann, R; Zimmermann, U; Haase, A

    1998-04-01

    Quantitative magnetic resonance (MR) images of flow velocities in intact corn plants were acquired using magnetization-prepared MR microscopy. A phase contrast flow imaging technique was used to quantitate water flow velocities and total volume flow rates in small xylem vessels. The simultaneous measurement of the transpiration of the whole plant was achieved by using a closed climate chamber within the MR magnet. The total volume flow rate and the transpiration values were in close correlation. Functional magnetic resonance imaging in intact plants was performed by light stimulation of the transpiration inside of the magnet. The change in the flow velocities in the xylem vessels of single vascular bundles was in correlation with the changes in the transpiration. Significant differences were observed between the xylem vessels in different vascular bundles. Furthermore, flow velocity measurements were performed on excised plant stems and visualized by the uptake of the MR contrast agent, gadolinium-diethylenetriamine pentaacetic acid (Gd-DTPA). A comparison between the phase contrast flow imaging and the contrast media uptake showed to be in good agreement with each other. PMID:9621974

  20. Magnetic structure determination from the magnetic pair distribution function (mPDF): ground state of MnO.

    PubMed

    Frandsen, Benjamin A; Billinge, Simon J L

    2015-05-01

    An experimental determination of the magnetic pair distribution function (mPDF) defined in an earlier paper [Frandsen et al. (2014). Acta Cryst. A70, 3-11] is presented for the first time. The mPDF was determined from neutron powder diffraction data from a reactor and a neutron time-of-flight total scattering source on a powder sample of the antiferromagnetic oxide MnO. A description of the data treatment that allowed the measured mPDF to be extracted and then modelled is provided and utilized to investigate the low-temperature structure of MnO. Atomic and magnetic co-refinements support the scenario of a locally monoclinic ground-state atomic structure, despite the average structure being rhombohedral, with the mPDF analysis successfully recovering the known antiferromagnetic spin configuration. The total scattering data suggest a preference for the spin axis to lie along the pseudocubic [10{\\overline 1}] direction. Finally, r-dependent PDF refinements indicate that the local monoclinic structure tends toward the average rhombohedral R{\\overline 3}m symmetry over a length scale of approximately 100 Å. PMID:25921501

  1. Analysis of the role of lead resistivity in specific absorption rate for deep brain stimulator leads at 3T MRI.

    PubMed

    Angelone, Leonardo M; Ahveninen, Jyrki; Belliveau, John W; Bonmassar, Giorgio

    2010-04-01

    Magnetic resonance imaging (MRI) on patients with implanted deep brain stimulators (DBSs) can be hazardous because of the antenna-effect of leads exposed to the incident radio-frequency field. This study evaluated electromagnetic field and specific absorption rate (SAR) changes as a function of lead resistivity on an anatomically precise head model in a 3T system. The anatomical accuracy of our head model allowed for detailed modeling of the path of DBS leads between epidermis and the outer table. Our electromagnetic finite difference time domain (FDTD) analysis showed significant changes of 1 g and 10 g averaged SAR for the range of lead resistivity modeled, including highly conductive leads up to highly resistive leads. Antenna performance and whole-head SAR were sensitive to the presence of the DBS leads only within 10%, while changes of over one order of magnitude were observed for the peak 10 g averaged SAR, suggesting that local SAR values should be considered in DBS guidelines. With rho(lead) = rho(copper) , and the MRI coil driven to produce a whole-head SAR without leads of 3.2 W/kg, the 1 g averaged SAR was 1080 W/kg and the 10 g averaged SAR 120 W/kg at the tip of the DBS lead. Conversely, in the control case without leads, the 1 g and 10 g averaged SAR were 0.5 W/kg and 0.6 W/kg, respectively, in the same location. The SAR at the tip of lead was similar with electrically homogeneous and electrically heterogeneous models. Our results show that computational models can support the development of novel lead technology, properly balancing the requirements of SAR deposition at the tip of the lead and power dissipation of the system battery. PMID:20335090

  2. Itinerant Electron Magnets: Curie Temperature and Susceptibility in Density-Functional Theory

    NASA Astrophysics Data System (ADS)

    Mohn, Peter; Khmelevskyi, Sergei

    Groundstate properties of solids are astonishingly well described by the local density functional approximation (LDA) [1]. This is also true of metallic magnets for which the situation was recently described by this author [2]. Excited-state properties of magnets (and other systems), however, are still a great challenge and it was believed until recently that the band-picture, based in the LDA, fails entirely in describing magnetism at elevated temperatures. We emphasize here that this is not so, attempting first to expose the reason why it was thought that the band-picture fails. Since historically the underlying physical picture was developed by Stoner and Wohlfarth, we begin with a discussion of their theory using, however, an approach that reveals the essential assumptions. This is Mermin's [3] finite-temperature density functional theory. Two points emerge: one is the essential noncollinearity of the magnetic moments at finite temperatures, the other is the form of the exchange-corr elation contribution to the thermodynamic potential. We know how to deal with noncollinear order in the LDA and we explain how we might use this knowledge to advance the issue. Exchange and correlation at finite temperatures are, however, at the present state not well understood. This statement not only applies to density functional theory but also to many-body treatments addressed at this workshop. We will show in particular that the theory of magnons in the band-LDA-picture at low temperatures is in good shape. At high temperatures we opt for a theory involving spin fluctuations and argue that, although broad features of the magnetic phase transition are described satisfactorily, many details await further improvements.

  3. Hydrazide functionalized core-shell magnetic nanocomposites for highly specific enrichment of N-glycopeptides.

    PubMed

    Liu, Liting; Yu, Meng; Zhang, Ying; Wang, Changchun; Lu, Haojie

    2014-05-28

    In view of the biological significance of glycosylation for human health, profiling of glycoproteome from complex biological samples is highly inclined toward the discovery of disease biomarkers and clinical diagnosis. Nevertheless, because of the existence of glycopeptides at relatively low abundances compared with nonglycosylated peptides and glycan microheterogeneity, glycopeptides need to be highly selectively enriched from complex biological samples for mass spectrometry analysis. Herein, a new type of hydrazide functionalized core-shell magnetic nanocomposite has been synthesized for highly specific enrichment of N-glycopeptides. The nanocomposites with both the magnetic core and the polymer shell hanging high density of hydrazide groups were prepared by first functionalization of the magnetic core with polymethacrylic acid by reflux precipitation polymerization to obtain the Fe3O4@poly(methacrylic acid) (Fe3O4@PMAA) and then modification of the surface of Fe3O4@PMAA with adipic acid dihydrazide (ADH) to obtain Fe3O4@poly(methacrylic hydrazide) (Fe3O4@PMAH). The abundant hydrazide groups toward highly specific enrichment of glycopeptides and the magnetic core make it suitable for large-scale, high-throughput, and automated sample processing. In addition, the hydrophilic polymer surface can provide low nonspecific adsorption of other peptides. Compared to commercially available hydrazide resin, Fe3O4@PMAH improved more than 5 times the signal-to-noise ratio of standard glycopeptides. Finally, this nanocomposite was applied in the profiling of N-glycoproteome from the colorectal cancer patient serum. In total, 175 unique glycopeptides and 181 glycosylation sites corresponding to 63 unique glycoproteins were identified in three repeated experiments, with the specificities of the enriched glycopeptides and corresponding glycoproteins of 69.6% and 80.9%, respectively. Because of all these attractive features, we believe that this novel hydrazide functionalized

  4. Configuration-dependent electronic and magnetic properties of graphene monolayers and nanoribbons functionalized with aryl groups

    SciTech Connect

    Tian, Xiaoqing Gu, Juan; Xu, Jian-bin

    2014-01-28

    Graphene monolayers functionalized with aryl groups exhibit configuration-dependent electronic and magnetic properties. The aryl groups were adsorbed in pairs of neighboring atoms in the same sublattice A (different sublattices) of graphene monolayers, denoted as the M{sub 2}{sup AA} (M{sub 2}{sup AB}) configuration. The M{sub 2}{sup AA} configuration behaved as a ferromagnetic semiconductor. The band gaps for the majority and minority bands were 1.1 eV and 1.2 eV, respectively. The M{sub 2}{sup AB} configuration behaved as a nonmagnetic semiconductor with a band gap of 0.8 eV. Each aryl group could induce 1 Bohr magneton (μ{sub B}) into the molecule-graphene system. Armchair graphene nanoribbons (GNRs) exhibited the same configuration-dependent magnetic properties as the graphene monolayers. The net spin of the functionalized zigzag GNRs was mainly localized on the edges demonstrating an adsorption site-dependent magnetism. For the zigzag GNRs, both the M{sub 2}{sup AA} and M{sub 2}{sup AB} configurations possibly had a magnetic moment. Each aryl group could induce 1.5–3.5 μ{sub B} into the molecule-graphene system. There was a metal-to-insulator transition after adsorption of the aryl groups for the zigzag GNRs.

  5. Surface functionalization of silica-coated magnetic nanoparticles for covalent attachment of cholesterol oxidase

    NASA Astrophysics Data System (ADS)

    Šulek, Franja; Drofenik, Miha; Habulin, Maja; Knez, Željko

    2010-01-01

    A systematic approach towards the fabrication of highly functionalized silica shell magnetic nanoparticles, presently used for enzyme immobilization, is herein fully presented. The synthesis of bare maghemite (γ-Fe 2O 3) nanoparticles was accomplished by thermal co-precipitation of iron ions in ammonia alkaline solution at harsh reaction conditions, respectively. Primary surface engineering of maghemite nanoparticles was successfully performed by the proper deposition of silica onto nanoparticles surface under strictly regulated reaction conditions. Next, the secondary surface functionalization of the particles was achieved by coating the particles with organosilane followed by glutaraldehyde activation in order to enhance protein immobilization. Covalent immobilization of cholesterol oxidase was attempted afterwards. The structural and magnetic properties of magnetic silica nanocomposites were characterized by TEM and vibrating sample magnetometer (VSM) instruments. X-ray diffraction measurements confirmed the spinel structure and average size of uncoated maghemite nanoparticles to be around 20 nm in diameter. SEM-EDS spectra indicated a strong signal for Si, implying the coating procedure of silica onto the particles surface to be successfully accomplished. Fourier transform infrared (FT-IR) spectra analysis confirmed the binding of amino silane molecules onto the surface of the maghemite nanoparticles mediated Si-O-Si chemical bonds. Compared to the free enzyme, the covalently bound cholesterol oxidase retained 50% of its activity. Binding of enzyme onto chemically modified magnetic nanoparticles via glutaraldehyde activation is a promising method for developing biosensing components in biomedicine.

  6. Isolation of N-linked glycopeptides by hydrazine-functionalized magnetic particles.

    PubMed

    Sun, Shisheng; Yang, Ganglong; Wang, Ting; Wang, Qinzhe; Chen, Chao; Li, Zheng

    2010-04-01

    We introduce a novel combination of magnetic particles with hydrazine chemistry, dubbed as hydrazine-functionalized magnetic particles (HFMP) for isolation of glycopeptides. Four methods have been developed and compared for the production of HFMP by hydrazine modification of the surface of the carboxyl and epoxy-silanized magnetic particles, respectively. The evaluation of the capability and specificity of HFMP as well as the optimization of the coupling condition for capturing of glycoproteins were systematically investigated. The results showed that HFMP prepared by adipic dihydrazide functionalization from carboxyl-silanized magnetic particles (HFCA) displayed the maximum capture capacity and isolated efficiency for glycoprotein. When measured with glycoproteins, the capacity of the HFCA (1 g) for coupling bovine fetuin was 130 +/- 5.3 mg. The capability of this method was also confirmed by successful isolation of all formerly glycosylated peptides from standard glycoproteins and identification of their glycosylation sites, which demonstrated the feasibility of the HFCA as an alternative solid support for isolation of glycoproteins/glycopeptides. PMID:20169334

  7. Functional expression of an scFv on bacterial magnetic particles by in vitro docking

    SciTech Connect

    Sugamata, Yasuhiro; Tanaka, Tsuyoshi; Matsunaga, Tadashi; Yoshino, Tomoko

    2014-02-28

    Highlights: • We present a novel expression system called “in vitro docking” on bacterial magnetic particles. • An scFv–Fc was functionally expressed on bacterial magnetic particles of magnetotactic bacteria. • Our novel expression system on BacMPs will be effective for disulfide-bonded proteins. - Abstract: A Gram-negative, magnetotactic bacterium, Magnetospirillum magneticum AMB-1 produces nano-sized magnetic particles (BacMPs) in the cytoplasm. Although various applications of genetically engineered BacMPs have been demonstrated, such as immunoassay, ligand–receptor interaction or cell separation, by expressing a target protein on BacMPs, it has been difficult to express disulfide-bonded proteins on BacMPs due to lack of disulfide-bond formation in the cytoplasm. Here, we propose a novel dual expression system, called in vitro docking, of a disulfide-bonded protein on BacMPs by directing an immunoglobulin Fc-fused target protein to the periplasm and its docking protein ZZ on BacMPs. By in vitro docking, an scFv–Fc fusion protein was functionally expressed on BacMPs in the dimeric or trimeric form. Our novel disulfide-bonded protein expression system on BacMPs will be useful for efficient screening of potential ligands or drugs, analyzing ligand–receptor interactions or as a magnetic carrier for affinity purification.

  8. Nature versus nurture: functional assessment of restoration effects on wetland services using Nuclear Magnetic Resonance Spectroscopy

    USGS Publications Warehouse

    Sundareshwar, P.V.; Richardson, C.J.; Gleason, R.A.; Pellechia, P.J.; Honomichl, S.

    2009-01-01

    Land-use change has altered the ability of wetlands to provide vital services such as nutrient retention. While compensatory practices attempt to restore degraded wetlands and their functions, it is difficult to evaluate the recovery of soil biogeochemical functions that are critical for restoration of ecosystem services. Using solution 31P Nuclear Magnetic Resonance Spectroscopy, we examined the chemical forms of phosphorus (P) in soils from wetlands located across a land-use gradient. We report that soil P diversity, a functional attribute, was lowest in farmland, and greatest in native wetlands. Soil P diversity increased with age of restoration, indicating restoration of biogeochemical function. The trend in soil P diversity was similar to documented trends in soil bacterial taxonomic composition but opposite that of soil bacterial diversity at our study sites. These findings provide insights into links between ecosystem structure and function and provide a tool for evaluating the success of ecosystem restoration efforts. Copyright 2009 by the American Geophysical Union.

  9. Development of magnetic resonance imaging based detection methods for beta amyloids via sialic acid-functionalized magnetic nanoparticles

    NASA Astrophysics Data System (ADS)

    Kouyoumdjian, Hovig

    The development of a non-invasive method for the detection of Alzheimer's disease is of high current interest, which can be critical in early diagnosis and in guiding preventive treatment of the disease. The aggregates of beta amyloids are a pathological hallmark of Alzheimer's disease. Carbohydrates such as sialic acid terminated gangliosides have been shown to play significant roles in initiation of amyloid aggregation. Herein, we report a biomimetic approach using sialic acid coated iron oxide superparamagnetic nanoparticles for in vitro detection in addition to the assessment of the in vivo mouse-BBB (Blood brain barrier) crossing of the BSA (bovine serum albumin)-modified ones. The sialic acid functionalized dextran nanoparticles were shown to bind with beta amyloids through several techniques including ELISA (enzyme linked immunosorbent assay), MRI (magnetic resonance imaging), TEM (transmission electron microscopy), gel electrophoresis and tyrosine fluorescence assay. The superparamagnetic nature of the nanoparticles allowed easy detection of the beta amyloids in mouse brains in both in vitro and ex vivo model by magnetic resonance imaging. Furthermore, the sialic acid nanoparticles greatly reduced beta amyloid induced cytotoxicity to SH-SY5Y neuroblastoma cells, highlighting the potential of the glyconanoparticles for detection and imaging of beta amyloids. Sialic acid functionalized BSA (bovine serum albumin) nanoparticles also showed significant binding to beta amyloids, through ELISA and ex vivo mouse brain MRI experiments. Alternatively, the BBB crossing was demonstrated by several techniques such as confocal microscopy, endocytosis, exocytosis assays and were affirmed by nanoparticles transcytosis assays through bEnd.3 endothelial cells. Finally, the BBB crossing was confirmed by analyzing the MRI signal of nanoparticle-injected CD-1 mice.

  10. Waiguan Stimulation May Kindle Anticorrelated Brain Networks: Functional Magnetic Resonance Imaging Data Revisited.

    PubMed

    Wik, Gustav; Huang, Yong; Zeng, Tongjun; Qu, Shanshan; Zheng, Yu; Zhang, Jiping; Lai, Xinsheng; Tang, Chunzhi; Shan, Baoci

    2016-02-01

    Subtraction of functional magnetic resonance imaging activity data results in a loss of information regarding possible general patterns of brain activation under experimental conditions. We, hence, reanalyzed previous Waiguan acupuncture data to qualitatively elucidate patterns of cerebral correlations to acupuncture and placebo conditions. Healthy individuals (n=24) were randomly allocated to true and sham Waiguan acupuncture and to true and sham needling of a nonacupuncture point (nonacupoint), and functional magnetic resonance imaging scans were performed during stimulation. Statistical parametric mapping group comparisons revealed clearly different patterns of activation between Waiguan stimulation and the corresponding stimulation of a nonacupoint. The former condition produced less neocortical activation than the nonacupoint stimulation. Cerebellar activation was typically seen only during true Waiguan acupuncture. The reduced neocortical activity during both true and sham Waiguan acupuncture may indicate that this point activates anticorrelated networks, with possible intrinsic healing properties. Cerebellar activation during true Waiguan acupuncture implies the region's influence on healing networks. PMID:26896073

  11. Functional mapping of the human visual cortex by magnetic resonance imaging

    SciTech Connect

    Belliveau, J.W.; Kennedy, D.N.; McKinstry, R.C.; Buchbinder, B.R.; Weisskoff, R.M.; Cohen, M.S.; Vevea, J.M.; Brady, T.J.; Rosen, B.R. Harvard Medical School, Boston, MA )

    1991-11-01

    Knowledge of regional cerebral hemodynamics has widespread application for both physiological research and clinical assessment because of the well-established interrelation between physiological function, energy metabolism, and localized blood supply. A magnetic resonance technique was developed for quantitative imaging of cerebral hemodynamics, allowing for measurement of regional cerebral blood volume during resting and activated cognitive states. This technique was used to generate the first functional magnetic resonance amps of human task activation, by using a visual stimulus paradigm. During photic stimulation, localized increases in blood volume (32 {plus minus} 10%, n = 7 subjects) were detected in the primary visual cortex. Center-of-mass coordinates and linear extends of brain activation within the plane of the calcarine fissure are reported.

  12. THE EFFECT OF MAGNETIC FIELDS AND AMBIPOLAR DIFFUSION ON CORE MASS FUNCTIONS

    SciTech Connect

    Bailey, Nicole D.; Basu, Shantanu E-mail: basu@uwo.ca

    2013-03-20

    Linear analysis of the formation of protostellar cores in planar magnetic interstellar clouds yields information about length scales involved in star formation. Combining these length scales with various distributions of other environmental variables (i.e., column density and mass-to-flux ratio) and applying Monte Carlo methods allow us to produce synthetic core mass functions (CMFs) for different environmental conditions. Our analysis shows that the shape of the CMF is directly dependent on the physical conditions of the cloud. Specifically, magnetic fields act to broaden the mass function and develop a high-mass tail while ambipolar diffusion will truncate this high-mass tail. In addition, we analyze the effect of small number statistics on the shape and high-mass slope of the synthetic CMFs. We find that observed CMFs are severely statistically limited, which has a profound effect on the derived slope for the high-mass tail.

  13. Dynamic contrast-enhanced magnetic resonance imaging: definitive imaging of placental function?

    PubMed

    Chalouhi, G E; Deloison, B; Siauve, N; Aimot, S; Balvay, D; Cuenod, C A; Ville, Y; Clément, O; Salomon, L J

    2011-02-01

    The placenta constitutes a complex circulatory interface between the mother and fetus, but the relationship between the maternal and fetal circulation is still very difficult to study in vivo. There is growing evidence that magnetic resonance imaging (MRI) is useful and safe during pregnancy, and MRI is increasingly used for fetal and placental anatomical imaging. MRI functional imaging is now a modern obstetric tool and has the potential to provide new insights into the physiology of the human placenta. Placental perfusion has been studied during the first pass of an MR contrast agent, by arterial spin labeling, diffusion imaging, T1 and T2 relaxation time measurement using echo-planar imaging, and by a combination of magnetization transfer with established stereological methods. The BOLD (blood oxygen level-dependent) effect offers new perspectives for functional MRI evaluation of the placenta. PMID:20851065

  14. Low-energy ion distribution functions on a magnetically quiet day at geostationary altitude /L = 7/

    NASA Technical Reports Server (NTRS)

    Singh, N.; Raitt, W. J.; Yasuhara, F.

    1982-01-01

    Ion energy and pitch angle distribution functions are examined for a magnetically quiet day using averaged data from ATS 6. For both field-aligned and perpendicular fluxes, the populations have a mixture of characteristic energies, and the distribution functions can be fairly well approximated by Maxwellian distributions over three different energy bands in the range 3-600 eV. Pitch angle distributions varying with local time, and energy distributions are used to compute total ion density. Pitch angle scattering mechanisms responsible for the observed transformation of pitch angle distribution are examined, and it is found that a magnetic noise of a certain power spectral density belonging to the electromagnetic ion cyclotron mode near the ion cyclotron frequency can be effective in trapping the field aligned fluxes by pitch angle scattering.

  15. Functional magnetic resonance microscopy at single-cell resolution in Aplysia californica

    PubMed Central

    Radecki, Guillaume; Nargeot, Romuald; Jelescu, Ileana Ozana; Le Bihan, Denis; Ciobanu, Luisa

    2014-01-01

    In this work, we show the feasibility of performing functional MRI studies with single-cell resolution. At ultrahigh magnetic field, manganese-enhanced magnetic resonance microscopy allows the identification of most motor neurons in the buccal network of Aplysia at low, nontoxic Mn2+ concentrations. We establish that Mn2+ accumulates intracellularly on injection into the living Aplysia and that its concentration increases when the animals are presented with a sensory stimulus. We also show that we can distinguish between neuronal activities elicited by different types of stimuli. This method opens up a new avenue into probing the functional organization and plasticity of neuronal networks involved in goal-directed behaviors with single-cell resolution. PMID:24872449

  16. A fast multiparameter MRI approach for acute stroke assessment on a 3T clinical scanner: preliminary results in a non-human primate model with transient ischemic occlusion

    PubMed Central

    Tong, Frank; Li, Chun-Xia; Yan, Yumei; Nair, Govind; Nagaoka, Tsukasa; Tanaka, Yoji; Zola, Stuart; Howell, Leonard

    2014-01-01

    Many MRI parameters have been explored and demonstrated the capability or potential to evaluate acute stroke injury, providing anatomical, microstructural, functional, or neurochemical information for diagnostic purposes and therapeutic development. However, the application of multiparameter MRI approach is hindered in clinic due to the very limited time window after stroke insult. Parallel imaging technique can accelerate MRI data acquisition dramatically and has been incorporated in modern clinical scanners and increasingly applied for various diagnostic purposes. In the present study, a fast multiparameter MRI approach including structural T1-weighted imaging (T1W), T2-weighted imaging (T2W), diffusion tensor imaging (DTI), T2-mapping, proton magnetic resonance spectroscopy, cerebral blood flow (CBF), and magnetization transfer (MT) imaging, was implemented and optimized for assessing acute stroke injury on a 3T clinical scanner. A macaque model of transient ischemic stroke induced by a minimal interventional approach was utilized for evaluating the multiparameter MRI approach. The preliminary results indicate the surgical procedure successfully induced ischemic occlusion in the cortex and/or subcortex in adult macaque monkeys (n=4). Application of parallel imaging technique substantially reduced the scanning duration of most MRI data acquisitions, allowing for fast and repeated evaluation of acute stroke injury. Hence, the use of the multiparameter MRI approach with up to five quantitative measures can provide significant advantages in preclinical or clinical studies of stroke disease. PMID:24834423

  17. Copper Ferrocyanide-Functionalized Magnetic Nanoparticles for the Selective Removal of Radioactive Cesium.

    PubMed

    Yang, Hee-Man; Lee, Kune-Woo; Seo, Bum-Kyoung; Moon, Jei-Kwon

    2015-02-01

    Copper ferrocyanide-functionalized magnetite nanoparticles (Cu-FC-MNPs) were successfully synthesized by immobilizing copper and ferrocyanide on the surfaces of [1-(2 amino-ethyl)-3-aminopropyl] trimethoxysilane-modified magnetite nanoparticles. Radioactive cesium (Cs) adsorption tests were conducted to investigate the effectiveness of the Cu-FC-MNPS toward the removal of radioactive Cs. The Cu-FC-MNPs showed excellent separation properties using an external magnet in an aqueous solution. PMID:26353716

  18. Early functional magnetic resonance imaging activations predict language outcome after stroke.

    PubMed

    Saur, Dorothee; Ronneberger, Olaf; Kümmerer, Dorothee; Mader, Irina; Weiller, Cornelius; Klöppel, Stefan

    2010-04-01

    An accurate prediction of system-specific recovery after stroke is essential to provide rehabilitation therapy based on the individual needs. We explored the usefulness of functional magnetic resonance imaging scans from an auditory language comprehension experiment to predict individual language recovery in 21 aphasic stroke patients. Subjects with an at least moderate language impairment received extensive language testing 2 weeks and 6 months after left-hemispheric stroke. A multivariate machine learning technique was used to predict language outcome 6 months after stroke. In addition, we aimed to predict the degree of language improvement over 6 months. 76% of patients were correctly separated into those with good and bad language performance 6 months after stroke when based on functional magnetic resonance imaging data from language relevant areas. Accuracy further improved (86% correct assignments) when age and language score were entered alongside functional magnetic resonance imaging data into the fully automatic classifier. A similar accuracy was reached when predicting the degree of language improvement based on imaging, age and language performance. No prediction better than chance level was achieved when exploring the usefulness of diffusion weighted imaging as well as functional magnetic resonance imaging acquired two days after stroke. This study demonstrates the high potential of current machine learning techniques to predict system-specific clinical outcome even for a disease as heterogeneous as stroke. Best prediction of language recovery is achieved when the brain activation potential after system-specific stimulation is assessed in the second week post stroke. More intensive early rehabilitation could be provided for those with a predicted poor recovery and the extension to other systems, for example, motor and attention seems feasible. PMID:20299389

  19. Multimodal imaging guided photothermal therapy using functionalized graphene nanosheets anchored with magnetic nanoparticles.

    PubMed

    Yang, Kai; Hu, Lilei; Ma, Xingxing; Ye, Shuoqi; Cheng, Liang; Shi, Xiaoze; Li, Changhui; Li, Yonggang; Liu, Zhuang

    2012-04-10

    In this work, a nanoscale reduced graphene oxide-iron oxide nanoparticle (RGO-IONP) complex is noncovalently functionalized with polyethylene glycol (PEG), obtaining a RGO-IONP-PEG nanocomposite with excellent physiological stability, strong NIR optical absorbance, and superparamagnetic properties. Using this theranostic nanoprobe, in-vivo triple modal fluorescence, photoacoustic, and magnetic resonance imaging are carried out, uncovering high passive tumor targeting, which is further used for effective photothermal ablation of tumors in mice. PMID:22378564

  20. Aberrant regional neural fluctuations and functional connectivity in generalized anxiety disorder revealed by resting-state functional magnetic resonance imaging.

    PubMed

    Wang, Wei; Hou, Jingming; Qian, Shaowen; Liu, Kai; Li, Bo; Li, Min; Peng, Zhaohui; Xin, Kuolin; Sun, Gang

    2016-06-15

    The purpose of this study was to investigate the neural activity and functional connectivity in generalized anxiety disorder (GAD) during resting state, and how these alterations correlate to patients' symptoms. Twenty-eight GAD patients and 28 matched healthy controls underwent resting-state functional magnetic resonance (fMRI) scans. Amplitude of low-frequency fluctuation (ALFF) and seed-based resting-state functional connectivity (RSFC) were computed to explore regional activity and functional integration, and were compared between the two groups using the voxel-based two-sample t test. Pearson's correlation analyses were performed to examine the neural relationships with demographics and clinical symptoms scores. Compared to controls, GAD patients showed functional abnormalities: higher ALFF in the bilateral dorsomedial prefrontal cortex, bilateral dorsolateral prefrontal cortex and left precuneus/posterior cingulate cortex; lower connectivity in prefrontal gyrus; lower in prefrontal-limbic and cingulate RSFC and higher prefrontal-hippocampus RSFC were correlated with clinical symptoms severity, but these associations were unable to withstand correction for multiple testing. These findings may help facilitate further understanding of the potential neural substrate of GAD. PMID:27163197

  1. Solar Magnetic Flux as a Function of Disk Position over the Solar Cycle

    NASA Astrophysics Data System (ADS)

    Berger, T.

    2005-05-01

    A novel analysis of a SOHO/MDI full-disk magnetogram time series from March 1996 to November 2004 is presented. Each of the 26,052 magnetograms in the series are segmented into sectors of constant μ = cos θ, each sector having a width of Δμ = 0.05. Within each sector, a histogram of signed magnetic flux density, corrected for the line-of-sight angle θ, is compiled. For each magnetogram we thus obtain a distribution of signed magnetic flux density as a function of μ. Summing the signed flux in each μ bin gives the total signed flux as a function of μ. Plotting these totals for each μ-sector as a function of time over the course of Solar Cycle 22 reveals that cycle minimum and maximum are differentiated only by the magnitude of the flux distributions. In other words, in contrast to analogous plots of flux versus heliocentric latitude, there is no discernible pattern, or "Butterfly Diagram", of flux seen on the solar disk from Earth. The finding is relevant to investigations of total solar irradiance (TSI) since it is known that the primary cause of the ~ 0.1% TSI variation over the solar cycle is the distribution of non-sunspot magnetic flux at smaller μ-values (so-called "faculae").

  2. Magnetically labelled gold and epoxy bi-functional microcarriers for suspension based bioassay technologies.

    PubMed

    Vyas, Kunal N; Palfreyman, Justin J; Love, David M; Mitrelias, Thanos; Barnes, Crispin H W

    2012-12-21

    Microarrays and suspension-based assay technologies have attracted significant interest over the past decade with applications ranging from medical diagnostics to high throughput molecular biology. The throughput and sensitivity of a microarray will always be limited by the array density and slow reaction kinetics. Suspension (or bead) based technologies offer a conceptually different approach, improving detection by substituting a fixed plane of operation with many individually distinguishable microcarriers. In addition to all the features of a suspension based assay technology, our technology offers a rewritable label. This has the potential to be truly revolutionary by opening up the possibility of generating, on chip, extensive labelled molecular libraries. We unveil our latest SU-8 microcarrier design with embedded magnetic films that can be utilized for both magnetic and optical labelling. The novel design significantly simplifies fabrication and additionally incorporates a gold cap to provide a dual surface, bi-functional architecture. The microcarriers are fabricated using deep-ultraviolet lithography techniques and metallic thin film growth by evaporation. The bi-functional properties of the microcarriers will allow us to use each microcarrier as its own positive control thereby increasing the reliability of our technology. Here we present details of the design, fabrication, magnetic detection and functionalization of these microcarriers. PMID:23128508

  3. Magnetic properties of f-electron systems in spin-polarized relativistic density functional theory

    NASA Astrophysics Data System (ADS)

    Yamagami, H.; Mavromaras, A.; Kübler, J.

    1997-12-01

    The magnetic ground state of the series of lanthanide and actinide trivalent ions is investigated by means of spin-polarized relativistic spin-density functional theory. In the local density functional approximation (LDA) an internal effective magnetic field due to exchange and correlation couples to the spin degrees of freedom. The resulting set of coupled Dirac equations yields ground-state multiplets that obey the well-known Hund's rules. This remarkable result comes about by the coupling of the j = l + 1/2 with the j = l - 1/2 states due to the exchange - correlation potential that is, as usual, the functional derivative of the exchange - correlation energy with respect to the spin magnetic moment. The effect of the coupling is shown to depend on the varying relative strengths of spin - orbit coupling and exchange splitting within the f series. Since in the f levels the internal exchange splitting dominates rather than the spin - orbit splitting, the energy level scheme is that of the Paschen - Back effect, and thus features of the Russell - Saunders coupling persist in spite of relativistic effects.

  4. Advanced magnetic resonance neuroimaging of language function recovery after aphasic stroke: a technical review.

    PubMed

    Smits, Marion; Visch-Brink, Evy G; van de Sandt-Koenderman, Mieke E; van der Lugt, Aad

    2012-01-01

    Two advanced magnetic resonance neuroimaging techniques, functional magnetic resonance imaging (fMRI) and diffusion tensor imaging (DTI), have recently made their way into clinically oriented research and hold great promise to study the brain's adaptive changes of function and structure after aphasic stroke, respectively. Such functional and structural neuroplasticity is thought to underlie the recovery of language function, occurring spontaneously and/or in the context of therapeutic intervention. With fMRI, brain activity can be visualized. Spontaneous brain activity, present in multiple brain networks, is measured with resting-state fMRI and language-related brain activity by having the subject perform a language task during scanning (task-based fMRI). With DTI the major white matter tracts, such as the dorsal and ventral language pathways and the commissural fibers, can be visualized and quantified. Both techniques are entirely noninvasive and thus offer the unique opportunity to perform multiple assessments within the same subject. To gain more insight in functional and structural neuroplasticity after aphasic stroke, advanced magnetic resonance neuroimaging studies in specific patient populations, at several stages after stroke and in the course of language recovery, are needed. Such studies will help to clarify the influence of the many factors that play a role in the recovery of language function and are thus vital to further the development of aphasia therapy. Application of these techniques in aphasic stroke patients, however, is not without challenge. The purpose of this article is to discuss the methodologic challenges of fMRI and DTI in the assessment of language recovery after aphasic stroke. PMID:22202190

  5. Coronary Artery Anomalies and Variants: Technical Feasibility of Assessment with Coronary MR Angiography at 3 T1

    PubMed Central

    Gharib, Ahmed M.; Ho, Vincent B.; Rosing, Douglas R.; Herzka, Daniel A.; Stuber, Matthias; Arai, Andrew E.; Pettigrew, Roderic I.

    2008-01-01

    The purpose of this study was to prospectively use a whole-heart three-dimensional (3D) coronary magnetic resonance (MR) angiography technique specifically adapted for use at 3 T and a parallel imaging technique (sensitivity encoding) to evaluate coronary arterial anomalies and variants (CAAV). This HIPAA-compliant study was approved by the local institutional review board, and informed consent was obtained from all participants. Twenty-two participants (11 men, 11 women; age range, 18–62 years) were included. Ten participants were healthy volunteers, whereas 12 participants were patients suspected of having CAAV. Coronary MR angiography was performed with a 3-T MR imager. A 3D free-breathing navigator-gated and vector electrocardiographically–gated segmented k-space gradient-echo sequence with adiabatic T2 preparation pulse and parallel imaging (sensitivity encoding) was used. Whole-heart acquisitions (repetition time msec/echo time msec, 4/1.35; 20° flip angle; 1 × 1 × 2-mm acquired voxel size) lasted 10–12 minutes. Mean examination time was 41 minutes ± 14 (standard deviation). Findings included aneurysms, ectasia, arteriovenous fistulas, and anomalous origins. The 3D whole-heart acquisitions developed for use with 3 T are feasible for use in the assessment of CAAV. © RSNA, 2008 PMID:18372470

  6. MR images of mouse brain using clinical 3T MR scanner and 4CH-Mouse coil

    NASA Astrophysics Data System (ADS)

    Lim, Soo Mee; Park, Eun Mi; Lyoo, In Kyoon; Lee, Junghyun; Han, Bo Mi; Lee, Jeong Kyong; Lee, Su Bin

    2015-07-01

    Objectives: Although small-bore high-field magnets are useful for research in small rodent models,this technology, however, has not been easily accessible to most researchers. This current study, thus,tried to evaluate the usability of 4CH-Mouse coil (Philips Healthcare, Best, the Netherlands) forpreclinical investigations in clinical 3T MR scan environment. We evaluated the effects of ischemicpreconditioning (IP) in the mouse stroke model with clinical 3T MR scanner and 4CH-Mouse coil. Materials and Methods: Experiments were performed on male C57BL/6 mice that either received the IP or sham operation (control). Three different MR sequences including diffusion weighted images (DWI), T2-weighted images (T2WI), and fluid attenuated inversion recovery (FLAIR) were performed on the mouse brains following 24, 72 hours of middle cerebral artery occlusion (MCAO) and analyzed for infarct lesions. Results: The images showed that the IP-treated mouse brains had significantly smaller infarct volumes compared to the control group. Of the MR sequences employed, the T2WI showed the highest level of correlations with postmortem infarct volume measurements. Conclusions: The clinical 3T MR scanner turned out to have a solid potential as a practical tool for imaging small animal brains. MR sequences including DWI, T2WI, FLAIR were obtained with acceptable resolution and in a reasonable time constraint in evaluating a mouse stroke model brain.

  7. Perpendicularly propagating electromagnetic modes in a strongly magnetized hot plasma with non-Maxwellian distribution function

    SciTech Connect

    Zaheer, S.; Murtaza, G.; Shah, H.A.

    2006-06-15

    Electromagnetic modes (ordinary and extraordinary) for strongly magnetized plasma are studied and their damping factors {gamma}{sub or} and {gamma}{sub ex} are calculated using non-Maxwellian velocity distribution function. It is observed that for moderate values of the spectral indices r and q [used in (r, q) distribution functions], both the damping decrements show substantial change. As the value of the spectral index r increases for a fixed value of q, the damping increases for the O mode but decreases for the X mode. In the limiting case of r=0, q{yields}{infinity}, the damping factors reduce to the standard Maxwellian values.

  8. Delineating potential epileptogenic areas utilizing resting functional magnetic resonance imaging (fMRI) in epilepsy patients.

    PubMed

    Pizarro, Ricardo; Nair, Veena; Meier, Timothy; Holdsworth, Ryan; Tunnell, Evelyn; Rutecki, Paul; Sillay, Karl; Meyerand, Mary E; Prabhakaran, Vivek

    2016-08-01

    Seizure localization includes neuroimaging like electroencephalogram, and magnetic resonance imaging (MRI) with limited ability to characterize the epileptogenic network. Temporal clustering analysis (TCA) characterizes epileptogenic network congruent with interictal epileptiform discharges by clustering together voxels with transient signals. We generated epileptogenic areas for 12 of 13 epilepsy patients with TCA, congruent with different areas of seizure onset. Resting functional MRI (fMRI) scans are noninvasive, and can be acquired quickly, in patients with different levels of severity and function. Analyzing resting fMRI data using TCA is quick and can complement clinical methods to characterize the epileptogenic network. PMID:27362339

  9. Magnetism in undoped ZnS studied from density functional theory

    SciTech Connect

    Xiao, Wen-Zhi E-mail: llwang@hun.edu.cn; Rong, Qing-Yan; Xiao, Gang; Wang, Ling-ling E-mail: llwang@hun.edu.cn; Meng, Bo

    2014-06-07

    The magnetic property induced by the native defects in ZnS bulk, thin film, and quantum dots are investigated comprehensively based on density functional theory within the generalized gradient approximation + Hubbard U (GGA + U) approach. We find the origin of magnetism is closely related to the introduction of hole into ZnS systems. The relative localization of S-3p orbitals is another key to resulting in unpaired p-electron, due to Hund's rule. For almost all the ZnS systems under study, the magnetic moment arises from the S-dangling bonds generated by Zn vacancies. The charge-neutral Zn vacancy, Zn vacancy in 1− charge sate, and S vacancy in the 1+ charge sate produce a local magnetic moment of 2.0, 1.0, and 1.0 μ{sub B}, respectively. The Zn vacancy in the neutral and 1− charge sates are the important cause for the ferromagnetism in ZnS bulk, with a Curie temperature (T{sub C}) above room temperature. For ZnS thin film with clean (111) surfaces, the spins on each surface are ferromagnetically coupled but antiferromagnetically coupled between two surfaces, which is attributable to the internal electric field between the two polar (111) surfaces of the thin film. Only surface Zn vacancies can yield local magnetic moment for ZnS thin film and quantum dot, which is ascribed to the surface effect. Interactions between magnetic moments on S-3p states induced by hole-doping are responsible for the ferromagnetism observed experimentally in various ZnS samples.

  10. Model of controlled drug release from functionalized magnetic nanoparticles by a nonheating alternating-current magnetic field

    NASA Astrophysics Data System (ADS)

    Golovin, Yu. I.; Klyachko, N. L.; Gribanovskii, S. L.; Golovin, D. Yu.; Majouga, A. G.

    2016-03-01

    A magnetohydrodynamic model of controlled drug macromolecule release from transport magnetic nanoparticles covered by a polymer shell under the influence of a low-frequency (<1 kHz) nonheating magnetic field is described.

  11. Impact of a High Magnetic Field on the Orientation of Gravitactic Unicellular Organisms—A Critical Consideration about the Application of Magnetic Fields to Mimic Functional Weightlessness

    PubMed Central

    Simon, Anja; Waßer, Kai; Hauslage, Jens; Christianen, Peter C.M.; Albers, Peter W.; Lebert, Michael; Richter, Peter; Alt, Wolfgang; Anken, Ralf

    2014-01-01

    Abstract The gravity-dependent behavior of Paramecium biaurelia and Euglena gracilis have previously been studied on ground and in real microgravity. To validate whether high magnetic field exposure indeed provides a ground-based facility to mimic functional weightlessness, as has been suggested earlier, both cell types were observed during exposure in a strong homogeneous magnetic field (up to 30 T) and a strong magnetic field gradient. While swimming, Paramecium cells were aligned along the magnetic field lines; orientation of Euglena was perpendicular, demonstrating that the magnetic field determines the orientation and thus prevents the organisms from the random swimming known to occur in real microgravity. Exposing Astasia longa, a flagellate that is closely related to Euglena but lacks chloroplasts and the photoreceptor, as well as the chloroplast-free mutant E. gracilis 1F, to a high magnetic field revealed no reorientation to the perpendicular direction as in the case of wild-type E. gracilis, indicating the existence of an anisotropic structure (chloroplasts) that determines the direction of passive orientation. Immobilized Euglena and Paramecium cells could not be levitated even in the highest available magnetic field gradient as sedimentation persisted with little impact of the field on the sedimentation velocities. We conclude that magnetic fields are not suited as a microgravity simulation for gravitactic unicellular organisms due to the strong effect of the magnetic field itself, which masks the effects known from experiments in real microgravity. Key Words: Levitation—Microgravity—Gravitaxis—Gravikinesis—Gravity. Astrobiology 14, 205–215. PMID:24621307

  12. Impact of a high magnetic field on the orientation of gravitactic unicellular organisms--a critical consideration about the application of magnetic fields to mimic functional weightlessness.

    PubMed

    Hemmersbach, Ruth; Simon, Anja; Waßer, Kai; Hauslage, Jens; Christianen, Peter C M; Albers, Peter W; Lebert, Michael; Richter, Peter; Alt, Wolfgang; Anken, Ralf

    2014-03-01

    The gravity-dependent behavior of Paramecium biaurelia and Euglena gracilis have previously been studied on ground and in real microgravity. To validate whether high magnetic field exposure indeed provides a ground-based facility to mimic functional weightlessness, as has been suggested earlier, both cell types were observed during exposure in a strong homogeneous magnetic field (up to 30 T) and a strong magnetic field gradient. While swimming, Paramecium cells were aligned along the magnetic field lines; orientation of Euglena was perpendicular, demonstrating that the magnetic field determines the orientation and thus prevents the organisms from the random swimming known to occur in real microgravity. Exposing Astasia longa, a flagellate that is closely related to Euglena but lacks chloroplasts and the photoreceptor, as well as the chloroplast-free mutant E. gracilis 1F, to a high magnetic field revealed no reorientation to the perpendicular direction as in the case of wild-type E. gracilis, indicating the existence of an anisotropic structure (chloroplasts) that determines the direction of passive orientation. Immobilized Euglena and Paramecium cells could not be levitated even in the highest available magnetic field gradient as sedimentation persisted with little impact of the field on the sedimentation velocities. We conclude that magnetic fields are not suited as a microgravity simulation for gravitactic unicellular organisms due to the strong effect of the magnetic field itself, which masks the effects known from experiments in real microgravity. PMID:24621307

  13. A New Adaptive Diffusive Function for Magnetic Resonance Imaging Denoising Based on Pixel Similarity

    PubMed Central

    Heydari, Mostafa; Karami, Mohammad Reza

    2015-01-01

    Although there are many methods for image denoising, but partial differential equation (PDE) based denoising attracted much attention in the field of medical image processing such as magnetic resonance imaging (MRI). The main advantage of PDE-based denoising approach is laid in its ability to smooth image in a nonlinear way, which effectively removes the noise, as well as preserving edge through anisotropic diffusion controlled by the diffusive function. This function was first introduced by Perona and Malik (P-M) in their model. They proposed two functions that are most frequently used in PDE-based methods. Since these functions consider only the gradient information of a diffused pixel, they cannot remove noise in noisy images with low signal-to-noise (SNR). In this paper we propose a modified diffusive function with fractional power that is based on pixel similarity to improve P-M model for low SNR. We also will show that our proposed function will stabilize the P-M method. As experimental results show, our proposed function that is modified version of P-M function effectively improves the SNR and preserves edges more than P-M functions in low SNR. PMID:26955563

  14. Prediction of d^0 magnetism in self-interaction corrected density functional theory

    NASA Astrophysics Data System (ADS)

    Das Pemmaraju, Chaitanya

    2010-03-01

    Over the past couple of years, the phenomenon of ``d^0 magnetism'' has greatly intrigued the magnetism community [1]. Unlike conventional magnetic materials, ``d^0 magnets'' lack any magnetic ions with open d or f shells but surprisingly, exhibit signatures of ferromagnetism often with a Curie temperature exceeding 300 K. Current research in the field is geared towards trying to understand the mechanism underlying this observed ferromagnetism which is difficult to explain within the conventional m-J paradigm [1]. The most widely studied class of d^0 materials are un-doped and light element doped wide gap Oxides such as HfO2, MgO, ZnO, TiO2 all of which have been put forward as possible d0 ferromagnets. General experimental trends suggest that the magnetism is a feature of highly defective samples leading to the expectation that the phenomenon must be defect related. In particular, based on density functional theory (DFT) calculations acceptor defects formed from the O-2p states in these Oxides have been proposed as being responsible for the ferromagnetism [2,3]. However. predicting magnetism originating from 2p orbitals is a delicate problem, which depends on the subtle interplay between covalency and Hund's coupling. DFT calculations based on semi-local functionals such as the local spin-density approximation (LSDA) can lead to qualitative failures on several fronts. On one hand the excessive delocalization of spin-polarized holes leads to half-metallic ground states and the expectation of room-temperature ferromagnetism. On the other hand, in some cases a magnetic ground state may not be predicted at all as the Hund's coupling might be under estimated. Furthermore, polaronic distortions which are often a feature of acceptor defects in Oxides are not predicted [4,5]. In this presentation, we argue that the self interaction error (SIE) inherent to semi-local functionals is responsible for the failures of LSDA and demonstrate through various examples that beyond

  15. Functionalized magnetic mesoporous silica nanoparticles for U removal from low and high pH groundwater.

    PubMed

    Li, Dien; Egodawatte, Shani; Kaplan, Daniel I; Larsen, Sarah C; Serkiz, Steven M; Seaman, John C

    2016-11-01

    U(VI) species display limited adsorption onto sediment minerals and synthetic sorbents in pH <4 or pH >8 groundwater. In this work, magnetic mesoporous silica nanoparticles (MMSNs) with magnetite nanoparticle cores were functionalized with various organic molecules using post-synthetic methods. The functionalized MMSNs were characterized using N2 adsorption-desorption isotherms, thermogravimetric analysis (TGA), transmission electron microscopy (TEM), (13)C cross polarization and magic angle spinning (CPMAS) nuclear magnetic resonance (NMR) spectroscopy, and powder X-ray diffraction (XRD), which indicated that mesoporous silica (MCM-41) particles of 100-200nm formed around a core of magnetic iron oxide, and the functional groups were primarily grafted into the mesopores of ∼3.0nm in size. The functionalized MMSNs were effective for U removal from pH 3.5 and 9.6 artificial groundwater (AGW). Functionalized MMSNs removed U from the pH 3.5 AGW by as much as 6 orders of magnitude more than unfunctionalized nanoparticles or silica and had adsorption capacities as high as 38mg/g. They removed U from the pH 9.6 AGW as much as 4 orders of magnitude greater than silica and 2 orders of magnitude greater than the unfunctionalized nanoparticles with adsorption capacities as high as 133mg/g. These results provide an applied solution for treating U contamination that occurs at extreme pH environments and a scientific foundation for solving critical industrial issues related to environmental stewardship and nuclear power production. PMID:27341378

  16. 26 CFR 1.444-3T - Manner and time of making section 444 election (temporary).

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 26 Internal Revenue 6 2012-04-01 2012-04-01 false Manner and time of making section 444 election (temporary). 1.444-3T Section 1.444-3T Internal Revenue INTERNAL REVENUE SERVICE, DEPARTMENT OF THE TREASURY (CONTINUED) INCOME TAX (CONTINUED) INCOME TAXES (CONTINUED) Accounting Periods § 1.444-3T Manner and time of making section 444 election...

  17. Removal of total organic carbon from sewage wastewater using poly(ethylenimine)-functionalized magnetic nanoparticles.

    PubMed

    Lakshmanan, Ramnath; Sanchez-Dominguez, Margarita; Matutes-Aquino, Jose A; Wennmalm, Stefan; Kuttuva Rajarao, Gunaratna

    2014-02-01

    The increased levels of organic carbon in sewage wastewater during recent years impose a great challenge to the existing wastewater treatment process (WWTP). Technological innovations are therefore sought that can reduce the release of organic carbon into lakes and seas. In the present study, magnetic nanoparticles (NPs) were synthesized, functionalized with poly(ethylenimine) (PEI), and characterized using TEM (transmission electron microscopy), X-ray diffraction (XRD), FTIR (Fourier transform infrared spectroscopy), CCS (confocal correlation spectroscopy), SICS (scattering interference correlation spectroscopy), magnetism studies, and thermogravimetric analysis (TGA). The removal of total organic carbon (TOC) and other contaminants using PEI-coated magnetic nanoparticles (PEI-NPs) was tested in wastewater obtained from the Hammarby Sjöstadsverk sewage plant, Sweden. The synthesized NPs were about 12 nm in diameter and showed a homogeneous particle size distribution in dispersion by TEM and CCS analyses, respectively. The magnetization curve reveals superparamagnetic behavior, and the NPs do not reach saturation because of surface anisotropy effects. A 50% reduction in TOC was obtained in 60 min when using 20 mg/L PEI-NPs in 0.5 L of wastewater. Along with TOC, other contaminants such as turbidity (89%), color (86%), total nitrogen (24%), and microbial content (90%) were also removed without significant changes in the mineral ion composition of wastewater. We conclude that the application of PEI-NPs has the potential to reduce the processing time, complexity, sludge production, and use of additional chemicals in the WWTP. PMID:24428551

  18. Functionalized magnetic carbonaceous microspheres for trypsin immobilization and the application to fast proteolysis.

    PubMed

    Yao, Guoping; Qi, Dawei; Deng, Chunhui; Zhang, Xiangmin

    2008-12-26

    In this study, magnetic carbonaceous (MC) microspheres prepared with a large-scale synthesis approach were developed as the novel substrate for enzyme immobilization, and the trypsin-immobilized MC microspheres were successfully applied to protein fast digestion. Firstly, MC microspheres with small size, strong magnetism, and biological compatibility were prepared through two-step solvothermal reactions. Secondly, MC microsphere surface was modified by 3-glycidoxypropyltrimethoxysilane (GLYMO). Finally, the enzyme was immobilized on the GLYMO-functionalized MC microspheres. The enzyme-immobilized magnetic microspheres were applied for fast protein digestion with microwave-assistance. Bovine serum albumin, myoglobin and cytochrome c, were used as model proteins to verify the digestion efficiency, and the digestion products were then characterized using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS) with sequence coverage of 43%, 90% and 77%, respectively. The enzyme-immobilized magnetic particles were also successfully applied to the analysis of human pituitary extract. After database search, 485 proteins (p<0.01) were identified when the extract was digested by the microspheres. This opens a route for its future application in bottom-up proteomic analysis. PMID:19026420

  19. Localized crustal magnetic field inversion using inner- and outer-source altitude vector Slepian functions

    NASA Astrophysics Data System (ADS)

    Plattner, A.; Simons, F. J.

    2015-12-01

    When inverting for a planetary magnetic potential from vector-valued satellite magnetic field data we need to take into account that the recorded data also contain fields not stemming from the planet but from outer sources in space. In classical global spherical-harmonic analysis this is done by fitting, in addition to the inner sources potential field, a linear combination of outer-source spherical harmonics to the data. This approach has been successfully applied to data with global homogeneous coverage and quality but is not suited for purely regional data. In many situations a local method would be beneficial to take full advantage of data with regionally varying quality or coverage, or to avoid ringing artifacts from sharp intensity contrasts. Here we present a local method that allows such a magnetic source separation. We simultaneously create inner-source and outer-source altitude vector Slepian functions by solving an optimization problem that considers the satellite altitude, the upper radial limit of the satellite trajectory, and the maximum spherical-harmonic degree we want to resolve. This new dual-source altitude vector Slepian system allows to invert for both inner-source and outer-source magnetic potential fields from regional data in a computationally efficient manner, as we show with a series of examples for Earth, the Moon, and terrestrial planets.

  20. Arrangement for measuring the field angle of a magnetic field as a function of axial position within a magnet bore tube

    DOEpatents

    Pidcoe, Stephen V.; Zink, Roger A.; Boroski, William N.; McCaw, William R.

    1993-01-01

    An arrangement for measuring the field angle of a magnetic field as a function of axial position within a magnet bore tube of a magnet such as is used with the Superconducting Super Collider (SSC). The arrangement includes a magnetic field alignment gauge that is carried through the magnet bore tube by a positioning shuttle in predetermined increments. The positioning shuttle includes an extensible body assembly which is actuated by an internal piston arrangement. A pair of spaced inflatable cuffs are carried by the body assembly and are selectively actuated in cooperation with pressurizing of the piston to selectively drive the positioning shuttle in an axial direction. Control of the shuttle is provided by programmed electronic computer means located exteriorly of the bore tube and which controls valves provided pressurized fluid to the inflatable cuss and the piston arrangement.

  1. Ursolic Acid Inhibits Adipogenesis in 3T3-L1 Adipocytes through LKB1/AMPK Pathway

    PubMed Central

    He, Yonghan; Li, Ying; Zhao, Tiantian; Wang, Yanwen; Sun, Changhao

    2013-01-01

    Background Ursolic acid (UA) is a triterpenoid compound with multiple biological functions. This compound has recently been reported to possess an anti-obesity effect; however, the mechanisms are less understood. Objective As adipogenesis plays a critical role in obesity, the present study was conducted to investigate the effect of UA on adipogenesis and mechanisms of action in 3T3-L1 preadipocytes. Methods and Results The 3T3-L1 preadipocytes were induced to differentiate in the presence or absence of UA for 6 days. The cells were determined for proliferation, differentiation, fat accumulation as well as the protein expressions of molecular targets that regulate or are involved in fatty acid synthesis and oxidation. The results demonstrated that ursolic acid at concentrations ranging from 2.5 µM to 10 µM dose-dependently attenuated adipogenesis, accompanied by reduced protein expression of CCAAT element binding protein β (C/EBPβ), peroxisome proliferator-activated receptor γ (PPARγ), CCAAT element binding protein α (C/EBPα) and sterol regulatory element binding protein 1c (SREBP-1c), respectively. Ursolic acid increased the phosphorylation of acetyl-CoA carboxylase (ACC) and protein expression of carnitine palmitoyltransferase 1 (CPT1), but decreased protein expression of fatty acid synthase (FAS) and fatty acid-binding protein 4 (FABP4). Ursolic acid increased the phosphorylation of AMP-activated protein kinase (AMPK) and protein expression of (silent mating type information regulation 2, homolog) 1 (Sirt1). Further studies demonstrated that the anti-adipogenic effect of UA was reversed by the AMPK siRNA, but not by the Sirt1 inhibitor nicotinamide. Liver kinase B1 (LKB1), the upstream kinase of AMPK, was upregulated by UA. When LKB1 was silenced with siRNA or the inhibitor radicicol, the effect of UA on AMPK activation was diminished. Conclusions Ursolic acid inhibited 3T3-L1 preadipocyte differentiation and adipogenesis through the LKB1/AMPK pathway

  2. Exact transfer functions for the PEP storage ring magnets and some general characteristics and techniques

    SciTech Connect

    Spencer, J.E.

    1982-05-01

    The exact, ion-optical transfer functions for the dipoles, quadrupoles and sextupoles of the PEP standard PODC cell are calculated for any single particle with initial coordinates (r, p, s). Modifications resulting from radiative energy loss are also calculated and discussed. These functions allow one to characterize individual magnets or classes of magnets by their aberrations and thereby simplify their study and correction. In contrast to high-energy spectrometers where aberrations are often analyzed away, those in storage rings drive series of high order resonances, even for perfect magnets (2), that can produce stop bands and other effects which can seriously limit performance. Thus, one would like to eliminate them altogether or failing this to develop local and global correction schemes. Even then, one should expect higher order effects to influence injection, extraction or single-pass systems either because of orbit distortions or overly large phase spece distortions such as may occur in low-beta insertions or any final-focus optics. The term exact means that the results here are based on solving the relativistic Lorentz force equation with accurate representations of measured magnetostatic fields. Such fields satisfy Maxwell's equations and are the actual fields seen by a particle as it propagates around a real storage ring. This is discussed in detail and illustrated with examples that show that this is possible, practical and may even be useful.

  3. Recent advances in surface chemistry strategies for the fabrication of functional iron oxide based magnetic nanoparticles

    NASA Astrophysics Data System (ADS)

    Turcheniuk, Kostiantyn; Tarasevych, Arkadii V.; Kukhar, Valeriy P.; Boukherroub, Rabah; Szunerits, Sabine

    2013-10-01

    The synthesis of superparamagnetic nanostructures, especially iron-oxide based nanoparticles (IONPs), with appropriate surface functional groups has been intensively researched for many high-technological applications, including high density data storage, biosensing and biomedicine. In medicine, IONPs are nowadays widely used as contrast agents for magnetic resonance imaging (MRI), in hyperthermia therapy, but are also exploited for drug and gene delivery, detoxification of biological fluids or immunoassays, as they are relatively non-toxic. The use of magnetic particles in vivo requires IONPs to have high magnetization values, diameters below 100 nm with overall narrow size distribution and long time stability in biological fluids. Due to the high surface energies of IONPs agglomeration over time is often encountered. It is thus of prime importance to modify their surface to prevent aggregation and to limit non-specific adsorption of biomolecules onto their surface. Such chemical modifications result in IONPs being well-dispersed and biocompatible, and allow for targeted delivery and specific interactions. The chemical nature of IONPs thus determines not only the overall size of the colloid, but also plays a significant role for in vivo and in vitro applications. This review discusses the different concepts currently used for the surface functionalization and coating of iron oxide nanoparticles. The diverse strategies for the covalent linking of drugs, proteins, enzymes, antibodies, and nucleotides will be discussed and the chemically relevant steps will be explained in detail.

  4. Succinate Functionalization of Hyperbranched Polyglycerol-Coated Magnetic Nanoparticles as a Draw Solute During Forward Osmosis.

    PubMed

    Yang, Hee-Man; Choi, Hye Min; Jang, Sung-Chan; Han, Myeong Jin; Seo, Bum-Kyoung; Moon, Jei-Kwon; Lee, Kune-Woo

    2015-10-01

    Hyperbranched polyglycerol-coated magnetic nanoparticles (SHPG-MNPs) were functionalized with succinate groups to form a draw solute for use in a forward osmosis (FO). After the one-step synthesis of hyperbranched polyglycerol-coated magnetic nanoparticles (HPG-MNPs), the polyglycerol groups on the surfaces of the HPG-MNPs were functionalized with succinic anhydride moieties. The resulting SHPG-MNPs showed no change of size and magnetic property compared with HPG-MNPs and displayed excellent dispersibility in water up to the concentration of 400 g/L. SHPG-MNPs solution showed higher osmotic pressure than that of HPG-MNPs solution due to the presence of surface carboxyl groups in SHPG-MNPs and could draw water from a feed solution across an FO membrane without any reverse draw solute leakage during FO process. Moreover, the water flux remained nearly constant over several SHPG-MNP darw solute regeneration cycles applied to the ultrafiltration (UF) process. The SHPG-MNPs demonstrate strong potential for use as a draw solute in FO processes. PMID:26726503

  5. MULTIPASS MUON RLA RETURN ARCS BASED ON LINEAR COMBINED-FUNCTION MAGNETS

    SciTech Connect

    Vasiliy Morozov, Alex Bogacz, Yves Roblin, Kevin Beard

    2011-09-01

    Recirculating Linear Accelerators (RLA) are an efficient way of accelerating short-lived muons to the multi-GeV energies required for Neutrino Factories and TeV energies required for Muon Colliders. In this paper we present a design of a two-pass RLA return arc based on linear combined function magnets, in which both charge muons with momenta different by a factor of two are transported through the same string of magnets. The arc is composed of 60{sup o}-bending symmetric super cells allowing for a simple arc geometry closing. By adjusting the dipole and quadrupole components of the combined-function magnets, each super cell is designed to be achromatic and to have zero initial and final periodic orbit offsets for both muon momenta. Such a design provides a greater compactness than, for instance, an FFAG lattice with its regular alternating bends and is expected to possess a large dynamic aperture characteristic of linear-field lattices.

  6. Highly Stable Amine Functionalized Iron Oxide Nanoparticles Designed for Magnetic Particle Imaging (MPI)

    PubMed Central

    Arami, Hamed; Krishnan, Kannan M.

    2014-01-01

    Magnetic particle imaging (MPI) is a promising medical imaging technology that uses iron oxide nanoparticles (NPs) as clinically safe tracers. The core and hydrodynamic size of these NPs determine the signal intensity and spatial resolution in MPI, whilst their monodispersity when preserved during the biomedical applications, generates a consistently high quality MPI image. Using an effective process to coat the synthesized NPs with amine terminated PEG molecules, we show by dynamic light scattering (DLS) that they are water-soluble with long-term stability in biological media such as phosphate buffered saline (PBS) and sodium bicarbonate buffers and Dulbecco’s modified Eagle medium (DMEM) enriched with 10% fetal bovine serum (FBS). Further, using magnetic particle spectroscopy (MPS), to measure the particle response function (PRF), defined as the derivative of the magnetization of the nanoparticles, we predict the MPI performance of these nanoparticles at a driving field frequency of 25 kHz. The MPS efficacy of the functionalized nanoparticles was also monitored over time, and both signal intensity and resolution remained unchanged even after seven days of incubation. This is attributed to the dominant contribution of the Néel relaxation mechanism of the monodisperse and highly stable nanoparticles, which was preserved through the incubation period. PMID:25554710

  7. Density-functional-theory calculations of matter in strong magnetic fields. I. Atoms and molecules

    SciTech Connect

    Medin, Zach; Lai Dong

    2006-12-15

    We present calculations of the electronic structure of various atoms and molecules in strong magnetic fields ranging from B=10{sup 12} G to 2x10{sup 15} G, appropriate for radio pulsars and magnetars. For these field strengths, the magnetic forces on the electrons dominate over the Coulomb forces, and to a good approximation the electrons are confined to the ground Landau level. Our calculations are based on the density functional theory, and use a local magnetic exchange-correlation function which is tested to be reliable in the strong field regime. Numerical results of the ground-state energies are given for H{sub N} (up to N=10), He{sub N} (up to N=8), C{sub N} (up to N=5), and Fe{sub N} (up to N=3), as well as for various ionized atoms. Fitting formulae for the B dependence of the energies are also given. In general, as N increases, the binding energy per atom in a molecule, vertical bar E{sub N}|/N, increases and approaches a constant value. For all the field strengths considered in this paper, hydrogen, helium, and carbon molecules are found to be bound relative to individual atoms (although for B less than a few x10{sup 12} G, carbon molecules are very weakly bound relative to individual atoms). Iron molecules are not bound at B < or approx. 10{sup 13} G, but become energetically more favorable than individual atoms at larger field strengths.

  8. SiN-SiC nanofilm: A nano-functional ceramic with bipolar magnetic semiconducting character

    SciTech Connect

    Zhang, Jiahui; Li, Xingxing; Yang, Jinlong

    2014-04-28

    Nowadays, functional ceramics have been largely explored for application in various fields. However, magnetic functional ceramics for spintronics remain little studied. Here, we propose a nano-functional ceramic of sphalerite SiN-SiC nanofilm with intrinsic ferromagnetic order. Based on first principles calculations, the SiN-SiC nanofilm is found to be a ferromagnetic semiconductor with an indirect band gap of 1.71 eV. By mean field theory, the Curie temperature is estimated to be 304 K, close to room temperature. Furthermore, the valence band and conduction band states of the nanofilm exhibit inverse spin-polarization around the Fermi level. Thus, the SiN-SiC nanofilm is a typical bipolar magnetic semiconductor in which completely spin-polarized currents with reversible spin polarization can be created and controlled by applying a gate voltage. Such a nano-functional ceramic provides a possible route for electrical manipulation of carrier's spin orientation.

  9. Increased Visibility of Deep Medullary Veins in Leukoaraiosis: A 3-T MRI Study

    PubMed Central

    Yan, Shenqiang; Wan, Jinping; Zhang, Xuting; Tong, Lusha; Zhao, Song; Sun, Jianzhong; Lin, Yuehan; Shen, Chunhong; Lou, Min

    2013-01-01

    Cerebral venous collagenosis has been implicated in leading to white matter hyperintensities (WMHs) via venous ischemia. We sought to determine whether cerebral venous dilation or ischemia correlate with the severity of WMHs by quantitative in vivo imaging techniques. This was an investigator-initiated prospective single-center study. We reviewed clinical, laboratory data from 158 consecutive WMHs patients and 50 controls, and measured the number of voxels of deep medullary veins (DMVs) on susceptibility-weighted image and assessed the WMH volume (as a marker of the severity of WMHs) on a 3-T magnetic resonance system. We then performed the logistic-regression analysis and partial Pearson’s correlation analysis to examine the association between the venous voxel count and WMH volume. The number of voxels of DMVs was significantly higher in WMHs than in controls. Increased number of voxels of DMVs was independently associated with both WMH volume of the whole brain and coregistered regional WMH volume after adjusting for age and number of lacunes. Our study indicates that cerebral deep venous insufficiency or ischemia play a role in the pathogenesis of WMHs, which may provide prognostic information on patients with WMHs and may have implications for therapeutic interventions. PMID:25071553

  10. Improved localisation for 2-hydroxyglutarate detection at 3T using long-TE semi-LASER

    PubMed Central

    Berrington, Adam; Voets, Natalie L.; Plaha, Puneet; Larkin, Sarah J.; Mccullagh, James; Stacey, Richard; Yildirim, Muhammed; Schofield, Christopher J.; Jezzard, Peter; Cadoux-Hudson, Tom; Ansorge, Olaf; Emir, Uzay E.

    2016-01-01

    2-hydroxyglutarate (2-HG) has emerged as a biomarker of tumour cell IDH mutations that may enable the differential diagnosis of glioma patients. At 3 Tesla, detection of 2-HG with magnetic resonance spectroscopy is challenging because of metabolite signal overlap and a spectral pattern modulated by slice selection and chemical shift displacement. Using density matrix simulations and phantom experiments, an optimised semi-LASER scheme (TE = 110 ms) improves localisation of the 2-HG spin system considerably compared to an existing PRESS sequence. This results in a visible 2-HG peak in the in vivo spectra at 1.9 ppm in the majority of IDH mutated tumours. Detected concentrations of 2-HG were similar using both sequences, although the use of semi-LASER generated narrower confidence intervals. Signal overlap with glutamate and glutamine, as measured by pairwise fitting correlation was reduced. Lactate was readily detectable across glioma patients using the method presented here (mean CLRB: (10±2)%). Together with more robust 2-HG detection, long TE semi-LASER offers the potential to investigate tumour metabolism and stratify patients in vivo at 3T. PMID:27547821

  11. In vivo conductivity imaging of canine male pelvis using a 3T MREIT system

    NASA Astrophysics Data System (ADS)

    Kim, H. J.; Jeong, W. C.; Kim, Y. T.; Minhas, A. S.; Lee, T. H.; Lim, C. Y.; Park, H. M.; Seo, J. K.; Woo, E. J.

    2010-04-01

    The prostate is an imaging area of growing concern related with aging. Prostate cancer and benign prostatic hyperplasia are the most common diseases and significant cause of death for elderly men. Hence, the conductivity imaging of the male pelvis is a challenging task with a clinical significance. In this study, we performed in vivo MREIT imaging experiments of the canine male pelvis using a 3T MRI scanner. Adopting carbon-hydrogel electrodes and a multi-echo pulse sequence, we could inject as much as 10 mA current in a form of 51 ms pulse into the pelvis. Collecting magnetic flux density data inside the pelvis subject to multiple injection currents, we reconstructed cross-sectional conductivity images using a MREIT software package CoReHA. Scaled conductivity images of the prostate show a clear contrast between the central and peripheral zones which are related with prostate diseases including cancer and benign prostatic hyperplasia. In our future work, we will focus on prostate cancer model animal experiments.

  12. Electronic and magnetic properties of silicon supported organometallic molecular wires: a density functional theory (DFT) study

    NASA Astrophysics Data System (ADS)

    Liu, Xia; Tan, Yingzi; Li, Xiuling; Wu, Xiaojun; Pei, Yong

    2015-08-01

    The electronic and magnetic properties of transition metal (TM = Sc, Ti, V, Cr and Mn) atom incorporated single and double one-dimensional (1D) styrene molecular wires confined on the hydrogen-terminated Si(100) surface are explored for the first time by means of spin-polarized density functional theory, denoted as Si-[TM(styrene)]. It is unveiled that TM atoms bind asymmetrically to the adjacent phenyl rings, which leads to novel electronic and magnetic properties in stark contrast to the well-studied gas phase TM-benzene molecular wires. Si-[Mn(styrene)]∞ and Si-[Cr(styrene)]∞ single molecular wires (SMWs) are a ferromagnetic semiconductor and half metal, respectively. Creation of H-atom defects on the silicon surface can introduce an impurity metallic band, which leads to novel half-metallic magnetism of a Si-[Mn(styrene)]∞ system. Moreover, double molecular wires (DMWs) containing two identical or hetero SMWs are theoretically designed. The [Mn(styrene)]∞-[Cr(styrene)]∞ DMW exhibits half-metallic magnetism where the spin-up and spin-down channels are contributed by two single molecular wires. Finally, we demonstrate that introducing a TM-defect may significantly affect the electronic structure and magnetic properties of molecular wires. These studies provide new insights into the structure and properties of surface supported 1-D sandwiched molecular wires and may inspire the future experimental synthesis of substrate confined organometallic sandwiched molecular wires.The electronic and magnetic properties of transition metal (TM = Sc, Ti, V, Cr and Mn) atom incorporated single and double one-dimensional (1D) styrene molecular wires confined on the hydrogen-terminated Si(100) surface are explored for the first time by means of spin-polarized density functional theory, denoted as Si-[TM(styrene)]. It is unveiled that TM atoms bind asymmetrically to the adjacent phenyl rings, which leads to novel electronic and magnetic properties in stark contrast to

  13. Electronic and magnetic properties of yttrium-doped silicon carbide nanotubes: Density functional theory investigations

    SciTech Connect

    Khaira, Jobanpreet S.; Jain, Richa N.; Chakraborty, Brahmananda; Ramaniah, Lavanya M.

    2015-06-24

    The electronic structure of yttrium-doped Silicon Carbide Nanotubes has been theoretically investigated using first principles density functional theory (DFT). Yttrium atom is bonded strongly on the surface of the nanotube with a binding energy of 2.37 eV and prefers to stay on the hollow site at a distance of around 2.25 Å from the tube. The semi-conducting nanotube with chirality (4, 4) becomes half mettalic with a magnetic moment of 1.0 µ{sub B} due to influence of Y atom on the surface. There is strong hybridization between d orbital of Y with p orbital of Si and C causing a charge transfer from d orbital of the Y atom to the tube. The Fermi level is shifted towards higher energy with finite Density of States for only upspin channel making the system half metallic and magnetic which may have application in spintronic devices.

  14. Collective magnetic behavior of biocompatible systems of maghemite particles coated with functional polymer shells

    NASA Astrophysics Data System (ADS)

    Demchenko, P.; Nedelko, N.; Mitina, N.; Lewińska, S.; Dłużewski, P.; Greneche, J. M.; Ubizskii, S.; Navrotskyi, S.; Zaichenko, A.; Ślawska-Waniewska, A.

    2015-04-01

    Three series of core-shell maghemite nanoparticles were prepared by a template synthesis using surface active oligoperoxides and further surface initiated grafting functional polymers, forming shell suitable for biomedical applications. Because the polymer shells prevent exchange coupling between maghemite particles, the overall magnetic properties of the samples studied are dominated by dipolar interparticle interactions. Only the sample with the highest polymer fraction displays superparamagnetic relaxation phenomena close to the room temperature. On cooling, the magnetostatic interactions lead to a disordered collective magnetic state that should be described in terms of a spin-glass phenomenology. This collective freezing cannot however be considered as a generic spin-glass phase transition at a well-defined temperature but rather as freezing to a metastable glass-like state of locally correlated structural domains (clusters) without a long-range order. A quasi static spin ordering is only achieved at temperatures much below the freezing temperature.

  15. Electronic and magnetic properties of substituted BN sheets: A density functional theory study

    SciTech Connect

    Zhou, Yungang; Yang, Ping; Wang, Zhiguo; Zu, Xiaotao T.; Xiao, Hai Yan; Sun, Xin; Khaleel, Mohammad A.; Gao, Fei

    2011-04-15

    Using density functional calculations, we investigate the geometries, electronic structures and magnetic properties of hexagonal BN sheets with 3d transition metal (TM) and nonmetal atoms embedded in three types of vacancies: VB, VN, and VB+N. We show that some embedded configurations, except TM atoms in VN vacancy, are stable in BN sheet and yield interesting phenomena. For instance, the band gaps and magnetic moments of BN sheet can be tuned depending on the embedded dopant species and vacancy type. In particular, embedment such as Cr in VB+N, Co in VB, and Ni in VB leads to half-metallic BN sheets interesting for spin filter applications. From the investigation of Mn-chain (CMn) embedments, a regular 1D structure can be formed in BN sheet as an electron waveguide, a metal nanometer wire with a single atom thickness.

  16. Physiological basis and image processing in functional magnetic resonance imaging: Neuronal and motor activity in brain

    PubMed Central

    Sharma, Rakesh; Sharma, Avdhesh

    2004-01-01

    Functional magnetic resonance imaging (fMRI) is recently developing as imaging modality used for mapping hemodynamics of neuronal and motor event related tissue blood oxygen level dependence (BOLD) in terms of brain activation. Image processing is performed by segmentation and registration methods. Segmentation algorithms provide brain surface-based analysis, automated anatomical labeling of cortical fields in magnetic resonance data sets based on oxygen metabolic state. Registration algorithms provide geometric features using two or more imaging modalities to assure clinically useful neuronal and motor information of brain activation. This review article summarizes the physiological basis of fMRI signal, its origin, contrast enhancement, physical factors, anatomical labeling by segmentation, registration approaches with examples of visual and motor activity in brain. Latest developments are reviewed for clinical applications of fMRI along with other different neurophysiological and imaging modalities. PMID:15125779

  17. Removal of aqueous uranyl ions by magnetic functionalized carboxymethylcellulose and adsorption property investigation

    NASA Astrophysics Data System (ADS)

    Gao, Yangyang; Yuan, Yali; Ma, Dandan; Li, Le; Li, Yuhui; Xu, Wenhui; Tao, Wei

    2014-10-01

    Magnetic carboxymethylcellulose (CMC/Fe3O4) was used as a framework adsorption material to remove uranium ions from aqueous solutions. Carboxyl functional groups were grafted onto the CMC/Fe3O4. The maximum adsorption capacity of the magnetic composite toward U(VI) was 122.48 mg/g. Kinetic and thermodynamic parameters of the adsorption process were estimated. The pseudo-second-order model was more suitable and it proved to be an endothermic and spontaneous process. The Langmuir and Freundlich models were applied to evaluate the adsorption isotherm. The data matched well with Langmuir model after equilibrium was reached and with Freundlich model before equilibrium was reached.

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

    PubMed Central

    2012-01-01

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

  19. Development of Magnetic Resonance-based Functional Imaging: The Past, the Present, and the Future.

    PubMed

    Matsumoto, Ken-Ichiro

    2016-01-01

    The term "theranostics" is a compound word combining "therapeutics" and "diagnostics". Discovery of the X-ray made an extraordinary contribution to the field of medical science. Development of computer science after World War II has been absolutely imperative for the development of medical imaging technology to date. The invention of X-ray computed tomography (CT) has revolutionized medical image diagnostic systems. Several functional imaging modalities emerged not only in the radiological field but also in magnetic resonance and ultrasonic fields. The fusion of three digital imaging techniques, MR Redox imaging, electron paramagnetic resonance (EPR) oxygen mapping, and hyperpolarized (13)C MRI techniques in the magnetic resonance field, contribute to the newly-termed theranostics. Future development of a suitable contrast agent for each imaging modality will be a key for the success of theranositics. PMID:27477720

  20. Electronic and magnetic properties of yttrium-doped silicon carbide nanotubes: Density functional theory investigations

    NASA Astrophysics Data System (ADS)

    Khaira, Jobanpreet S.; Jain, Richa N.; Chakraborty, Brahmananda; Ramaniah, Lavanya M.

    2015-06-01

    The electronic structure of yttrium-doped Silicon Carbide Nanotubes has been theoretically investigated using first principles density functional theory (DFT). Yttrium atom is bonded strongly on the surface of the nanotube with a binding energy of 2.37 eV and prefers to stay on the hollow site at a distance of around 2.25 Å from the tube. The semi-conducting nanotube with chirality (4, 4) becomes half mettalic with a magnetic moment of 1.0 µB due to influence of Y atom on the surface. There is strong hybridization between d orbital of Y with p orbital of Si and C causing a charge transfer from d orbital of the Y atom to the tube. The Fermi level is shifted towards higher energy with finite Density of States for only upspin channel making the system half metallic and magnetic which may have application in spintronic devices.

  1. Regulation of p53 in NIH3T3 mouse fibroblasts following hyperosmotic stress.

    PubMed

    Lambert, Ian Henry; Enghoff, Maria Stine; Brandi, Marie-Luise; Hoffmann, Else Kay

    2015-06-01

    The aim of this project was to analyze the regulation of p53 expression in NIH3T3 fibroblasts under the influence of increasing hyperosmotic stress. Expression of p53 showed a biphasic response pattern in NIH3T3 cells under increasing osmotic stress (337 mOsm to 737 mOsm) with a maximum at 587 mOsm. Under isotonic conditions p53 expression increased after addition of the proteasome inhibitor MG132 indicating that cellular p53 levels in unperturbed cells is kept low by proteasomal degradation. However, under hypertonic conditions p53 synthesis as well as p53 degradation were significantly reduced and it is demonstrated that the increase in p53 expression observed when tonicity is increased from 337 to 587 mOsm reflects that degradation is more inhibited than synthesis, whereas the decrease in p53 expression at higher tonicities reflects that synthesis is more inhibited than degradation. The activity of the p53 regulating proteins p38 MAP kinase and the ubiquitin ligase MDM2 were studied as a function of increasing osmolarity. MDM2 protein expression was unchanged at all osmolarities, whereas MDM2 phosphorylation (Ser(166)) increased at osmolarities up to 537 mOsm and remained constant at higher osmolarities. Phosphorylation of p38 increased at osmolarities up to 687 mOsm which correlated with an increased phosphorylation of p53 (Ser(15)) and the decreased p53 degradation. Caspase-3 activity increased gradually with hypertonicity and at 737 mOsm both Caspase-3 activity and annexin V binding are high even though p53 expression and activity are low, indicating that initiation of apoptosis under severe hypertonic conditions is not strictly controlled by p53. PMID:26056062

  2. Regulation of p53 in NIH3T3 mouse fibroblasts following hyperosmotic stress

    PubMed Central

    Lambert, Ian Henry; Enghoff, Maria Stine; Brandi, Marie-Luise; Hoffmann, Else Kay

    2015-01-01

    The aim of this project was to analyze the regulation of p53 expression in NIH3T3 fibroblasts under the influence of increasing hyperosmotic stress. Expression of p53 showed a biphasic response pattern in NIH3T3 cells under increasing osmotic stress (337 mOsm to 737 mOsm) with a maximum at 587 mOsm. Under isotonic conditions p53 expression increased after addition of the proteasome inhibitor MG132 indicating that cellular p53 levels in unperturbed cells is kept low by proteasomal degradation. However, under hypertonic conditions p53 synthesis as well as p53 degradation were significantly reduced and it is demonstrated that the increase in p53 expression observed when tonicity is increased from 337 to 587 mOsm reflects that degradation is more inhibited than synthesis, whereas the decrease in p53 expression at higher tonicities reflects that synthesis is more inhibited than degradation. The activity of the p53 regulating proteins p38 MAP kinase and the ubiquitin ligase MDM2 were studied as a function of increasing osmolarity. MDM2 protein expression was unchanged at all osmolarities, whereas MDM2 phosphorylation (Ser166) increased at osmolarities up to 537 mOsm and remained constant at higher osmolarities. Phosphorylation of p38 increased at osmolarities up to 687 mOsm which correlated with an increased phosphorylation of p53 (Ser15) and the decreased p53 degradation. Caspase-3 activity increased gradually with hypertonicity and at 737 mOsm both Caspase-3 activity and annexin V binding are high even though p53 expression and activity are low, indicating that initiation of apoptosis under severe hypertonic conditions is not strictly controlled by p53. PMID:26056062

  3. Rapid and specific influenza virus detection by functionalized magnetic nanoparticles and mass spectrometry

    PubMed Central

    2011-01-01

    Background The timely and accurate diagnosis of specific influenza virus strains is crucial to effective prophylaxis, vaccine preparation and early antiviral therapy. The detection of influenza A viruses is mainly accomplished using polymerase chain reaction (PCR) techniques or antibody-based assays. In conjugation with the immunoassay utilizing monoclonal antibody, mass spectrometry is an alternative to identify proteins derived from a target influenza virus. Taking advantage of the large surface area-to-volume ratio, antibody-conjugated magnetic nanoparticles can act as an effective probe to extract influenza virus for sodium dodecylsulfate polyacrylamide gel electrophoresis (SDS-PAGE) and on-bead mass spectrometric analysis. Results Iron oxide magnetic nanoparticles (MNP) were functionalized with H5N2 viral antibodies targeting the hemagglutinin protein and capped with methoxy-terminated ethylene glycol to suppress nonspecific binding. The antibody-conjugated MNPs possessed a high specificity to H5N2 virus without cross-reactivity with recombinant H5N1 viruses. The unambiguous identification of the captured hemagglutinin on magnetic nanoparticles was realized by SDS-PAGE visualization and peptide sequence identification using liquid chromatography-tandem mass spectrometry (LC-MS/MS). Conclusions The assay combining efficient magnetic separation and MALDI-MS readout offers a rapid and sensitive method for virus screening. Direct on-MNP detection by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) provided high sensitivity (~103 EID50 per mL) and a timely diagnosis within one hour. The magnetic nanoparticles encapsulated with monoclonal antibodies could be used as a specific probe to distinguish different subtypes of influenza. PMID:22088100

  4. A portable single-sided magnet system for remote NMR measurements of pulmonary function.

    PubMed

    Dabaghyan, Mikayel; Muradyan, Iga; Hrovat, Alan; Butler, James; Frederick, Eric; Zhou, Feng; Kyriazis, Angelos; Hardin, Charles; Patz, Samuel; Hrovat, Mirko

    2014-12-01

    In this work, we report initial results from a light-weight, low field magnetic resonance device designed to make relative pulmonary density measurements at the bedside. The development of this device necessarily involves special considerations for the magnet, RF and data acquisition schemes as well as a careful analysis of what is needed to provide useful information in the ICU. A homogeneous field region is created remotely from the surface of the magnet such that when the magnet is placed against the chest, an NMR signal is measured from a small volume in the lung. In order to achieve portability, one must trade off field strength and therefore spatial resolution. We report initial measurements from a ping-pong ball size region in the lung as a function of lung volume. As expected, we measured decreased signal at larger lung volumes since lung density decreases with increasing lung volume. Using a CPMG sequence with ΔTE=3.5 ms and a 20 echo train, a signal to noise ratio ~1100 was obtained from an 8.8mT planar magnet after signal averaging for 43 s. This is the first demonstration of NMR measurements made on a human lung with a light-weight planar NMR device. We argue that very low spatial resolution measurements of different lobar lung regions will provide useful diagnostic information for clinicians treating Acute Respiratory Distress Syndrome as clinicians want to avoid ventilator pressures that cause either lung over distension (too much pressure) or lung collapse (too little pressure). PMID:24953556

  5. A portable single-sided magnet system for remote NMR measurements of pulmonary function

    PubMed Central

    Mikayel, Dabaghyan; Iga, Muradyan; James, Butler; Eric, Frederick; Feng, Zhou; Angelos, Kyriazis; Charles, Hardin; Samuel, Patz; Mirko, Hrovat

    2014-01-01

    In this work, we report initial results from a light-weight, low field magnetic resonance device designed to make relative pulmonary density measurements at the bedside. The development of this device necessarily involves special considerations for the magnet, RF and data acquisition schemes as well as a careful analysis of what is needed to provide useful information in the ICU. A homogeneous field region is created remotely from the surface of the magnet such that when the magnet is placed against the chest, an NMR signal is measured from a small volume in the lung. In order to achieve portability, one must trade off field strength and therefore spatial resolution. We report initial measurements from a ping-pong ball size region in the lung as a function of lung volume. As expected, we measured decreased signal at larger lung volumes since lung density decreases with increasing lung volume. Using a CPMG sequence with ΔTE=3.5 ms and a 20 echo train, a signal to noise ratio ~1100 was obtained from an 8.8mT planar magnet after signal averaging for 43 s. This is the first demonstration of NMR measurements made on a human lung with a light-weight planar NMR device. We argue that very low spatial resolution measurements of different lobar lung regions will provide useful diagnostic information for clinicians treating Acute Respiratory Distress Syndrome as clinicians want to avoid ventilator pressures that cause either lung over distension (too much pressure) or lung collapse (too little pressure). PMID:24953556

  6. Phase transitions, magnetism and surface adsorptions assessed by meta-GGA functionals and random phase approximation

    NASA Astrophysics Data System (ADS)

    Xiao, Bing

    investigated the electronic structures and magnetism of R-VO2 using exchange-correlation functionals of all five rungs on Jacob's ladder. Our calculations show that all semilocal functionals (LSDA, GGAs and meta-GGAs) and hybrid functionals (HSE06) stabilize the spin-polarized states (ferromagnetic and anti-ferromagnetic states) over non-magentic state, which are completely opposite to experimental observation. Suprisingly, LSDA gives the best energetic descriptions for magnetic and non-magnetic phases of R-VO2 among semilocal functionals and HSE06. Othwerwise, RPA calculations are highly dependent on the inputs in the spin polarized case. With PBE inputs, RPA also fails, giving lower energies for spin-polarized states than for the non-magnetic phase. Meawhile, the results are reversed using LSDA inputs. From the computed equilibrium cell volume, we observe the error cancellation in the exchange-correlation hole of most semilocal functionals in the spin-polarized calculations. LSDA and RPA do not fit to this picture. By analyzing the local magnetic moments of vanadium atoms, it is found that the magnetic property predicted from meta-GGA can be related to its exchange enhancement factor. The physisorption of a molecule on a transition metal surface is also another difficult problem in DFT because of the long-range van der Waals interactions. The recently developed MGGA_MS family of density functionals is able to capture a portion of intermediate range dispersion interactions. Therefore, we employed MGGA_MS2 to study the physisorption of CO2 on Pt (111) surface, and the results are compared to those of PBE, PBE+D2 and optB88-vdW methods. The computed binding curves comfirm that that MGGA_MS2 indeed captures the van der Waals interactions near the equilibrium binding distance, and the obtained binding distance is also in good agreement with PBE+D2 and optB88-vdW calculations. By computing the electron density difference map (EDDM), we find that the electron densities of CO2 and

  7. Musical training-induced functional reorganization of the adult brain: functional magnetic resonance imaging and transcranial magnetic stimulation study on amateur string players.

    PubMed

    Kim, Dong-Eog; Shin, Min-Jung; Lee, Kyoung-Min; Chu, Kon; Woo, Sung Ho; Kim, Young Ro; Song, Eun-Cheol; Lee, Jun-Won; Park, Seong-Ho; Roh, Jae-Kyu

    2004-12-01

    We used the combined technique of functional magnetic resonance imaging (fMRI) and transcranial magnetic stimulation (TMS) to observe changes that occur in adult brains after the practice of stringed musical instruments. We carried out fMRI on eight volunteers (aged 20-22 years): five novices and three individuals who had discontinued practice for more than 5 years. The motor paradigm contained a repetitive lift-abduction/fall-adduction movement of the left/right little finger, carried out with maximum efforts without pacing. The sensory paradigm was to stimulate the same little finger using a string. In parallel to the fMRI acquisition, TMS motor maps for the little finger were obtained using a frameless stereotactic neuronavigation system. After the baseline study, each participant began to learn a stringed instrument. Newly developed fMRI activations for the left little finger were observed 6 months after practice at multiple brain regions including inferior parietal lobule, premotor area (PMA), left precuneus, right anterior superior temporal gyrus, and posterior middle temporal gyrus. In contrast, new activations were rarely observed for the right little finger. The TMS study revealed new motor representation sites for the left little finger in the PMA or supplementary motor area (SMA). Unexpectedly, TMS motor maps for the right little finger were reduced significantly. Among new fMRI activations for sensory stimuli of the left little finger, the cluster of highest activation was located in the SMA. Collectively, these data provide insight into orchestrated reorganization of the sensorimotor and temporal association cortices contributing to the skillful fingering and musical processing after the practice of playing stringed instruments. PMID:15449354

  8. An integrated framework for targeting functional networks via transcranial magnetic stimulation.

    PubMed

    Opitz, Alexander; Fox, Michael D; Craddock, R Cameron; Colcombe, Stan; Milham, Michael P

    2016-02-15

    Transcranial magnetic stimulation (TMS) is a powerful investigational tool for in vivo manipulation of regional or network activity, with a growing number of potential clinical applications. Unfortunately, the vast majority of targeting strategies remain limited by their reliance on non-realistic brain models and assumptions that anatomo-functional relationships are 1:1. Here, we present an integrated framework that combines anatomically realistic finite element models of the human head with resting functional MRI to predict functional networks targeted via TMS at a given coil location and orientation. Using data from the Human Connectome Project, we provide an example implementation focused on dorsolateral prefrontal cortex (DLPFC). Three distinct DLPFC stimulation zones were identified, differing with respect to the network to be affected (default, frontoparietal) and sensitivity to coil orientation. Network profiles generated for DLPFC targets previously published for treating depression revealed substantial variability across studies, highlighting a potentially critical technical issue. PMID:26608241

  9. Neural Correlates of Symptom Dimensions in Pediatric Obsessive-Compulsive Disorder: A Functional Magnetic Resonance Imaging Study

    ERIC Educational Resources Information Center

    Gilbert, Andrew R.; Akkal, Dalila; Almeida, Jorge R. C.; Mataix-Cols, David; Kalas, Catherine; Devlin, Bernie; Birmaher, Boris; Phillips, Mary L.

    2009-01-01

    The use of functional magnetic resonance imaging on a group of pediatric subjects with obsessive compulsive disorder reveals that this group has reduced activity in neural regions underlying emotional processing, cognitive processing, and motor performance as compared to control subjects.

  10. Global gene expression profiling of JMJD6- and JMJD4-depleted mouse NIH3T3 fibroblasts

    PubMed Central

    Hu, Yu-Jie; Imbalzano, Anthony N.

    2016-01-01

    Emerging evidence suggests Jumonji domain-containing proteins are epigenetic regulators in diverse biological processes including cellular differentiation and proliferation. RNA interference-based analyses combined with gene expression profiling can effectively characterize the cellular functions of these enzymes. We found that the depletion of Jumonji domain-containing protein 6 (JMJD6) and its paralog protein Jumonji domain-containing protein 4 (JMJD4) individually by small hairpin RNAs (shRNAs) slowed cell proliferation of mouse NIH3T3 fibroblasts. We subsequently performed gene expression profiling on both JMJD6- and JMJD4-depleted mouse NIH3T3 fibroblasts using the Affymetrix GeneChip Mouse Exon 1.0 ST Array. Here we report the gene profiling datasets along with the experimental procedures. The information can be used to further investigate how JMJD6 and JMJD4 affect gene expression and cellular physiology. PMID:27071056

  11. Vectorial Slepian functions and the estimation of the crustal magnetic field

    NASA Astrophysics Data System (ADS)

    Plattner, Alain; Simons, Frederik

    2013-04-01

    Within the past two decades increasingly sophisticated magnetometry satellite missions have brought us data of ever improving quality and will reach a new pinnacle with the Swarm satellite mission to be launched in 2013. In order to make optimal use of this rich source of information for the lithospheric structure of Earth, and other planets, the computational algorithms used to obtain the crustal magnetic field from satellite data should be designed to take the specific properties of the data into account (e.g. their bandlimitation, their noise properties, the satellite altitude, their vectorial character). Ideally, the method should also be able to focus on chosen regions, be it as a means of regularization in a specifically targeted investigation or in order to discern between areas of intrinsically different properties of the field, such as for example crustal versus oceanic field. Such a merging of properties can be achieved using Slepian functions, a basis of bandlimited and spatially concentrated functions. The scalar version of Slepian functions has proven to be useful in a wide range of fields including geodesy, gravimetry, geomagnetism, and geodynamics. In order to make use of all three components of the vectorial data set we recently developed vectorial Slepian functions. In this presentation we combine the vectorial Slepian functions with the up- and downward continuation of vector fields to construct a fully vectorial estimation scheme for the regional crustal magnetic field from data at satellite altitude. We test our method with artificial data for different regions and bandlimits and compare different implementations of the method including regional concentration at satellite altitude, regional concentration on Earth's surface, and an estimation scheme employing vectorial Slepian functions that are constructed to ideally incorporate the defocusing effect due to altitude continuation.

  12. Copper Ferrocyanide-Functionalized Magnetic Adsorbents Using Polyethyleneimine Coated Fe3O4 Nanoparticles for the Removal of Radioactive Cesium.

    PubMed

    Yang, Hee-Man; Hong, Sang Bum; Cho, Yong Suk; Lee, Kune-Woo; Seo, Bum-Kyoung; Moon, Jei-Kwon

    2016-03-01

    Copper ferrocyanide-functionalized magnetic nano-adsorbents were successfully synthesized by electrostatic coating of citric acid coated Fe3O4 nanoparticles with polyethyleneimine, and immobilizing copper and ferrocyanide on the surfaces of polyethyleneimine-coated nanoparticles. Radioactive cesium (Cs) adsorption tests were conducted to investigate the effectiveness of the copper ferrocyanide-functionalized magnetic nano-adsorbents toward the removal of radioactive Cs. PMID:27455762

  13. 26 CFR 1.6042-3T - Dividends subject to reporting (temporary).

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 26 Internal Revenue 13 2014-04-01 2014-04-01 false Dividends subject to reporting (temporary). 1.6042-3T Section 1.6042-3T Internal Revenue INTERNAL REVENUE SERVICE, DEPARTMENT OF THE TREASURY... paragraph (b)(1)(iii) may be reportable, for purposes of chapter 3 of the Internal Revenue Code...

  14. 26 CFR 1.702-3T - 4-Year spread (temporary).

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 26 Internal Revenue 8 2010-04-01 2010-04-01 false 4-Year spread (temporary). 1.702-3T Section 1... (CONTINUED) INCOME TAXES Partners and Partnerships § 1.702-3T 4-Year spread (temporary). (a) Applicability... spread. A partner may elect out of the rules of paragraph (b) of this section by meeting the...

  15. 26 CFR 1.702-3T - 4-Year spread (temporary).

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 26 Internal Revenue 8 2012-04-01 2012-04-01 false 4-Year spread (temporary). 1.702-3T Section 1... (CONTINUED) INCOME TAXES (CONTINUED) Partners and Partnerships § 1.702-3T 4-Year spread (temporary). (a... taxable year for the first taxable year beginning after December 31, 1986 (partnership's year of...

  16. Pre-clinical functional Magnetic Resonance Imaging Part I: The kidney.

    PubMed

    Zöllner, Frank G; Kalayciyan, Raffi; Chacón-Caldera, Jorge; Zimmer, Fabian; Schad, Lothar R

    2014-12-01

    The prevalence of chronic kidney disease (CKD) is increasing worldwide. In Europe alone, at least 8% of the population currently has some degree of CKD. CKD is associated with serious comorbidity, reduced life expectancy, and high economic costs; hence, the early detection and adequate treatment of kidney disease is important. Pre-clinical research can not only give insights into the mechanisms of the various kidney diseases but it also allows for investigating the outcome of new drugs developed to treat kidney disease. Functional magnetic resonance imaging provides non-invasive access to tissue and organ function in animal models. Advantages over classical animal research approaches are numerous: the same animal might be repeatedly imaged to investigate a progress or a treatment of disease over time. This has also a direct impact on animal welfare and the refinement of classical animal experiments as the number of animals in the studies might be reduced. In this paper, we review current state of the art in functional magnetic resonance imaging with a focus on pre-clinical kidney imaging. PMID:24931712

  17. Affinity capture using peptide-functionalized magnetic nanoparticles to target Staphylococcus aureus.

    PubMed

    Kuo, Fang-Yin; Lin, Wei-Lien; Chen, Yu-Chie

    2016-04-28

    Staphylococcus aureus, a commonly found pathogen, can cause food poisoning and infections. Thus, it is necessary to develop analytical methods for the rapid screening of S. aureus in suspicious samples. Magnetic nanoparticles (MNPs) are widely used as affinity probes to selectively enrich target species from complex samples because of their high specific surface area and magnetic properties. The MNP surface should be functionalized to have the capability to target specific species. We herein propose a straightforward method to functionalize aluminum oxide-coated iron oxide (Fe3O4@Al2O3) MNPs with the peptide HHHHHHDEEGLFVD (D). The peptide D was comprised of three domains: polyhistidine (H6) used as the linker, DEE added as the spacer, and GLFVD used for targeting S. aureus. D was immobilized on the surface of Fe3O4@Al2O3 MNPs through H6-Al chelation. Our results showed that the D-functionalized Fe3O4@Al2O3 MNPs (D-Fe3O4 MNPs) possess the capability to target S. aureus. The selective trapping experiments were conducted under microwave-heating for only 60 s, and sufficient bacterial cells were trapped by the MNPs to be identified by matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS). We demonstrated that the D-Fe3O4@Al2O3 MNPs combined with MALDI-MS can be used to rapidly characterize trace amounts of S. aureus in complex juice and egg samples. PMID:27087258

  18. Effect of weak, interrupted sinusoidal low frequency magnetic field on neural regeneration in rats: functional evaluation.

    PubMed

    Bervar, Marijan

    2005-07-01

    A study of the effect of weak, interrupted sinusoidal low frequency magnetic field (ISMF) stimulation on regeneration of the rat sciatic nerve was carried out. In the experiment, 60 Wistar rats were used: 24 rats underwent unilateral sciatic nerve transection injury and immediate surgical nerve repair, 24 rats underwent unilateral sciatic nerve crush injury, and the remaining 12 rats underwent a sham surgery. Half of the animals (n = 12) with either sciatic nerve lesion were randomly chosen and exposed between a pair of Helmholtz coils for 3 weeks post-injury, 4 h/day, to an interrupted (active period to pause ratio = 1.4 s/0.8 s) sinusoidal 50 Hz magnetic field of 0.5 mT. The other half of the animals (n = 12) and six rats with sham surgery were used for two separate controls. Functional recovery was followed for 6 weeks for the crush injuries and 7(1/2) months for the transection injuries by video assisted footprint analysis in static conditions and quantified using a recently revised static sciatic index (SSI) formula. We ascertained that the magnetic field influence was weak, but certainly detectable in both injury models. The accuracy of ISMF influence detection, determined by the one-way repeated measures ANOVA test, was better for the crush injury model: F(1, 198) = 9.0144, P = .003, than for the transection injury model: F(1, 198) = 6.4826, P = .012. The Student-Newman-Keuls range test for each response day yielded significant differences (P < .05) between the exposed and control groups early in the beginning of functional recovery and later on from the points adjacent to the beginning of the plateau, or 95% of functional recovery, and the end of observation. These differences probably reflect the ISMF systemic effect on the neuron cell bodies and increased and more efficient reinnervation of the periphery. PMID:15887258

  19. Design of covalently functionalized carbon nanotubes filled with metal oxide nanoparticles for imaging, therapy, and magnetic manipulation.

    PubMed

    Liu, Xiaojie; Marangon, Iris; Melinte, Georgian; Wilhelm, Claire; Ménard-Moyon, Cécilia; Pichon, Benoit P; Ersen, Ovidiu; Aubertin, Kelly; Baaziz, Walid; Pham-Huu, Cuong; Bégin-Colin, Sylvie; Bianco, Alberto; Gazeau, Florence; Bégin, Dominique

    2014-11-25

    Nanocomposites combining multiple functionalities in one single nano-object hold great promise for biomedical applications. In this work, carbon nanotubes (CNTs) were filled with ferrite nanoparticles (NPs) to develop the magnetic manipulation of the nanotubes and their theranostic applications. The challenges were both the filling of CNTs with a high amount of magnetic NPs and their functionalization to form biocompatible water suspensions. We propose here a filling process using CNTs as nanoreactors for high-yield in situ growth of ferrite NPs into the inner carbon cavity. At first, NPs were formed inside the nanotubes by thermal decomposition of an iron stearate precursor. A second filling step was then performed with iron or cobalt stearate precursors to enhance the encapsulation yield and block the formed NPs inside the tubes. Water suspensions were then obtained by addition of amino groups via the covalent functionalization of the external surface of the nanotubes. Microstructural and magnetic characterizations confirmed the confinement of NPs into the anisotropic structure of CNTs making them suitable for magnetic manipulations and MRI detection. Interactions of highly water-dispersible CNTs with tumor cells could be modulated by magnetic fields without toxicity, allowing control of their orientation within the cell and inducing submicron magnetic stirring. The magnetic properties were also used to quantify CNTs cellular uptake by measuring the cell magnetophoretic mobility. Finally, the photothermal ablation of tumor cells could be enhanced by magnetic stimulus, harnessing the hybrid properties of NP loaded-CNTs. PMID:25343751

  20. Investigating the emotional response to room acoustics: A functional magnetic resonance imaging study.

    PubMed

    Lawless, M S; Vigeant, M C

    2015-10-01

    While previous research has demonstrated the powerful influence of pleasant and unpleasant music on emotions, the present study utilizes functional magnetic resonance imaging (fMRI) to assess the positive and negative emotional responses as demonstrated in the brain when listening to music convolved with varying room acoustic conditions. During fMRI scans, subjects rated auralizations created in a simulated concert hall with varying reverberation times. The analysis detected activations in the dorsal striatum, a region associated with anticipation of reward, for two individuals for the highest rated stimulus, though no activations were found for regions associated with negative emotions in any subject. PMID:26520354

  1. Cerebral activation focusing on strong tasting food: a functional magnetic resonance imaging study.

    PubMed

    Kikuchi, Senichiro; Kubota, Fumio; Nisijima, Koichi; Washiya, Sumio; Kato, Satoshi

    2005-02-28

    Very little research has been conducted on taste imagery because of the difficulty of doing so. We conducted a functional magnetic resonance imaging study to observe cerebral activation patterns produced in volunteers concentrating on pickled plums (umeboshi), a traditional Japanese food with a strong and sour taste. Activation was observed in the right insula, the bilateral opercula, the bilateral orbitofrontal cortices and the left Broca's area. Activation in the insula (primary gustatory area) was very weak and limited to one side. The activation pattern was similar to that of taste perception. Our results showed that it is possible for humans to imagine tastes. PMID:15706236

  2. Magnetic resonance imaging biomarkers of gastrointestinal motor function and fluid distribution

    PubMed Central

    Khalaf, Asseel; Hoad, Caroline L; Spiller, Robin C; Gowland, Penny A; Moran, Gordon W; Marciani, Luca

    2015-01-01

    Magnetic resonance imaging (MRI) is a well established technique that has revolutionized diagnostic radiology. Until recently, the impact that MRI has had in the assessment of gastrointestinal motor function and bowel fluid distribution in health and in disease has been more limited, despite the novel insights that MRI can provide along the entire gastrointestinal tract. MRI biomarkers include intestinal motility indices, small bowel water content and whole gut transit time. The present review discusses new developments and applications of MRI in the upper gastrointestinal tract, the small bowel and the colon reported in the literature in the last 5 years. PMID:26600972

  3. Vital functions of organisms in infra-low frequency magnetic fields 3. The embryogeny of mammals

    SciTech Connect

    Khizhenkov, P.K.; Bilobrov, V.M.; Zinkevich, I.I.; Zyablitsev, S.V.

    1994-10-01

    Results are presented of the experimental studies of the effect of variable (rotary) magnetic fields H at f = 6.5 Hz on the reproduction function of rats. It is shown that a pregnancy does not occur when mating takes place under the action of the field H. In the second quarter of pregnancy, the effect of the field is characterized by an increase of the mass of the body and of the internal organs of the new-born rats, among which, the growth of gemmae, spleen and of the thymus gland are particularly significant. The relative composition of the white blood cells changes as well.

  4. Magnetically responsive ordered mesoporous materials: A burgeoning family of functional composite nanomaterials

    NASA Astrophysics Data System (ADS)

    Deng, Yonghui; Cai, Yue; Sun, Zhenkun; Zhao, Dongyuan

    2011-06-01

    Magnetic mesoporous materials, as a family of novel functional nanomaterials, have attracted increasing attention due to their unique properties. Much work has been done to synthesize these materials and to explore applications in various fields, such as catalysis, separation, hyperthermia, drug delivery, and MR imaging. This Letter reviews the synthesis approaches, which can be grouped into three categories, i.e. sol-gel coating, post-loading, and nanocasting approaches. Emphasis is placed on the elucidation of the design principles, synthesis strategies and the properties-applications relationship of the mesoporous materials.

  5. Combining Nuclear Magnetic Resonance Spectroscopy and Density Functional Theory Calculations to Characterize Carvedilol Polymorphs.

    PubMed

    Rezende, Carlos A; San Gil, Rosane A S; Borré, Leandro B; Pires, José Ricardo; Vaiss, Viviane S; Resende, Jackson A L C; Leitão, Alexandre A; De Alencastro, Ricardo B; Leal, Katia Z

    2016-09-01

    The experiments of carvedilol form II, form III, and hydrate by (13)C and (15)N cross-polarization magic-angle spinning (CP MAS) are reported. The GIPAW (gauge-including projector-augmented wave) method from DFT (density functional theory) calculations was used to simulate (13)C and (15)N chemical shifts. A very good agreement was found for the comparison between the global results of experimental and calculated nuclear magnetic resonance (NMR) chemical shifts for carvedilol polymorphs. This work aims a comprehensive understanding of carvedilol crystalline forms employing solution and solid-state NMR as well as DFT calculations. PMID:26372719

  6. Functional Magnetic Resonance Imaging of Motor Cortex: Hemispheric Asymmetry and Handedness

    NASA Astrophysics Data System (ADS)

    Kim, Seong-Gi; Ashe, James; Hendrich, Kristy; Ellermann, Jutta M.; Merkle, Hellmut; Ugurbil, Kamil; Georgopoulos, Apostolos P.

    1993-07-01

    A hemispheric asymmetry in the functional activation of the human motor cortex during contralateral (C) and ipsilateral (I) finger movements, especially in right-handed subjects, was documented with nuclear magnetic resonance imaging at high field strength (4 tesla). Whereas the right motor cortex was activated mostly during contralateral finger movements in both right-handed (C/I mean area of activation = 36.8) and left-handed (C/I = 29.9) subjects, the left motor cortex was activated substantially during ipsilateral movements in left-handed subjects (C/I = 5.4) and even more so in right-handed subjects (C/I = 1.3).

  7. H-1 Nuclear Magnetic Resonance Metabolomics Analysis Identifies Novel Urinary Biomarkers for Lung Function

    SciTech Connect

    MCClay, Joseph L.; Adkins, Daniel E.; Isern, Nancy G.; O'Connell, Thomas M.; Wooten, Jan B.; Zedler, Barbara K.; Dasika, Madhukar S.; Webb, B. T.; Webb-Robertson, Bobbie-Jo M.; Pounds, Joel G.; Murrelle, Edward L.; Leppert, Mark F.; van den Oord, Edwin J.

    2010-06-04

    Chronic obstructive pulmonary disease (COPD), characterized by chronic airflow limitation, is a serious and growing public health concern. The major environmental risk factor for COPD is tobacco smoking, but the biological mechanisms underlying COPD are not well understood. In this study, we used proton nuclear magnetic resonance (1H-NMR) spectroscopy to identify and quantify metabolites associated with lung function in COPD. Plasma and urine were collected from 197 adults with COPD and from 195 adults without COPD. Samples were assayed using a 600 MHz NMR spectrometer, and the resulting spectra were analyzed against quantitative spirometric measures of lung function. After correcting for false discoveries and adjusting for covariates (sex, age, smoking) several spectral regions in urine were found to be significantly associated with baseline lung function. These regions correspond to the metabolites trigonelline, hippurate and formate. Concentrations of each metabolite, standardized to urinary creatinine, were associated with baseline lung function (minimum p-value = 0.0002 for trigonelline). No significant associations were found with plasma metabolites. Two of the three urinary metabolites positively associated with baseline lung function, i.e. hippurate and formate, are often related to gut microflora. This suggests that the microbiome composition is variable between individuals with different lung function. Alternatively, the nature and origins of all three associated metabolites may reflect lifestyle differences affecting overall health. Our results will require replication and validation, but demonstrate the utility of NMR metabolomics as a screening tool for identifying novel biomarkers of lung disease or disease risk.

  8. The presupplementary area within the language network: a resting state functional magnetic resonance imaging functional connectivity analysis.

    PubMed

    Ter Minassian, Aram; Ricalens, Emmanuel; Nguyen The Tich, Sylvie; Dinomais, Mickaël; Aubé, Christophe; Beydon, Laurent

    2014-08-01

    The presupplementary motor area (pre-SMA) is involved in volitional selection. Despite the lateralization of the language network and different functions for both pre-SMA, few studies have reported the lateralization of pre-SMA activity and very little is known about the possible lateralization of pre-SMA connectivity. Via functional connectivity analysis, we sought to understand how the language network may be connected to other intrinsic connectivity networks (ICNs) through the pre-SMA. We performed a spatial independent component analysis of resting state functional magnetic resonance imaging in 30 volunteers to identify the language network. Subsequently, we applied seed-to-voxel functional connectivity analyses centered on peaks detected in the pre-SMA. Three signal peaks were detected in the pre-SMA. The left rostral pre-SMA intrinsic connectivity network (LR ICN) was left lateralized in contrast to bilateral ICNs associated to right pre-SMA peaks. The LR ICN was anticorrelated with the dorsal attention network and the right caudal pre-SMA ICN (RC ICN) anticorrelated with the default mode network. These two ICNs overlapped minimally. In contrast, the right rostral ICN overlapped the LR ICN. Both right ICNs overlapped in the ventral attention network (vATT). The bilateral connectivity of the right rostral pre-SMA may allow right hemispheric recruitment to process semantic ambiguities. Overlap between the right pre-SMA ICNs in vATT may contribute to internal thought to external environment reorientation. Distinct ICNs connected to areas involved in lexico-syntactic selection and phonology converge in the pre-SMA, which may constitute the resolution space of competing condition-action associations for speech production. PMID:24939724

  9. Testing the Jacob's ladder of density functionals for electronic structure and magnetism of rutile VO2

    NASA Astrophysics Data System (ADS)

    Xiao, Bing; Sun, Jianwei; Ruzsinszky, Adrienn; Perdew, John P.

    2014-08-01

    We employ semilocal density functionals [local spin-density approximation (LSDA), Perdew-Burke-Ernzerhof (PBE) generalized gradient approximation (GGA), and meta-GGAs)], LSDA plus Hubbard U (LSDA+U) theory, a nonlocal range-separated Heyd-Scuseria-Ernzerhof hybrid functional (HSE06), and the random-phase approximation (RPA) to assess their performances for the ground-state magnetism and electronic structure of a strongly correlated metal, rutile VO2. Using recent quantum Monte Carlo results as the benchmark, all tested semilocal and hybrid functionals as well as the RPA (with PBE inputs) predict the correct magnetic ground states for rutile VO2. The observed paramagnetism could arise from temperature-disordered local spin moments or from the thermal destruction of these moments. All semilocal functionals also give the correct ground-state metallicity for rutile VO2. However, in the ferromagnetic (FM) and antiferromagnetic (AFM) phases, LSDA+U and HSE06 incorrectly predict rutile VO2 to be a Mott-Hubbard insulator. For the computed electronic structures of FM and AFM phases, we find that the Tao-Perdew-Staroverov-Scuseria (TPSS) and revised TPSS (revTPSS) meta-GGAs give strong 2p-3d hybridizations, resulting in a depopulation of the 2p bands of O atoms, in comparison with other tested meta-GGAs. The regularized TPSS (regTPSS) and meta-GGAs made simple, i.e., MGGA_MS0 and MGGA_MS2, which are free of the spurious order-of-limits problem of TPSS and revTPSS, give electronic states close to those of the PBE GGA and LSDA. In comparison to experiment, semilocal functionals predict better equilibrium cell volumes for rutile VO2 in FM and AFM states than in the spin-unpolarized state. For meta-GGAs, a monotonic decrease of the exchange enhancement factor Fx(s,α) with α for small s, as in the MGGA_MS functionals, leads to large (probably too large) local magnetic moments in spin-polarized states.

  10. pH-responsive deoxyribonucleic acid capture/release by polydopamine functionalized magnetic nanoparticles.

    PubMed

    Wang, Yu; Ma, Xiangdong; Ding, Chun; Jia, Li

    2015-03-01

    Polydopamine functionalized magnetic nanoparticles (PDA@Fe3O4) were prepared and characterized by transmission electron microscopy, scanning electron microscopy, zeta potential and vibrating sample magnetometry. They were found to enable highly efficient capture of genomic deoxyribonucleic acid (DNA). The adsorption capacity of PDA@Fe3O4 for genomic DNA can reach 161 mg g(-1). The extraction protocol used aqueous solutions for DNA binding to and releasing from the surface of the magnetic particles based on the pH inducing the charge switch of amino and phenolic hydroxyl groups on PDA@Fe3O4. The extracted DNA with high quality (A260/A280=1.80) can be directly used as templates for polymerase chain reaction (PCR) followed by capillary electrophoresis (CE) analysis. None of the toxic chemical reagents and PCR inhibitors was used throughout the whole procedure. PDA@Fe3O4 based magnetic solid phase extraction (MSPE) method was superior to those using commercial kit and traditional phenol-chloroform extraction methods in yield of DNA. The developed PDA@Fe3O4 based MSPE-PCR-CE method was applied for simultaneous and fast detection of Listeria monocytogenes and Escherichia coli O157:H7 in milk. PMID:25682426

  11. One-step fabrication of amino functionalized magnetic graphene oxide composite for uranium(VI) removal.

    PubMed

    Chen, Lili; Zhao, Donglin; Chen, Shaohua; Wang, Xianbiao; Chen, Changlun

    2016-06-15

    Amino functionalized magnetic graphene oxide composite (AMGO), a good sorbent for U(VI), was fabricated and characterized. The AMGO was applied as a magnetic sorbent for the U(VI) removal from aqueous solutions. The AMGO can be easily recovered from the solution with the magnetic separation within one minute. The kinetic data were well-described by the pseudo-second-order equation. The Langmuir model fitted the sorption isotherm data better than the Freundlich model. The maximum sorption capacity of the AMGO for U(VI) was 141.2mg/g, displaying a high efficiency for the removal of U(VI). It was found that the U(VI) sorption was accomplished mainly via chelation or ion exchange. The thermodynamic parameters illustrated that the sorption process was spontaneous and endothermic in nature. In addition, the excellent reproducibility indicate that the AMGO can be used as a potential sorbent for removal of U(VI) from large volumes of aqueous solution. PMID:27016915

  12. High-capacity adsorption of dissolved hexavalent chromium using amine-functionalized magnetic corn stalk composites.

    PubMed

    Song, Wen; Gao, Baoyu; Zhang, Tengge; Xu, Xing; Huang, Xin; Yu, Huan; Yue, Qinyan

    2015-08-01

    Easily separable amine-functionalized magnetic corn stalk composites (AF-MCS) were employed for effective adsorption and reduction of toxic hexavalent chromium [Cr(VI)] to nontoxic Cr(III). The saturated magnetization of AF-MCS reached 6.2emu/g, and as a result, it could be separated from aqueous solution by a magnetic process for its superparamagnetism. The studies of various factors influencing the sorption behavior indicated that the optimum AF-MCS dosage for Cr(VI) adsorption was 1g/L, and the maximum adsorption capacity was observed at pH 3.0. The chromium adsorption perfectly fitted the Langmuir isotherm model and pseudo second order kinetic model. Furthermore, characterization of AF-MCS was investigated by means of XRD, SEM, TEM, FT-IR, BET, VSM and XPS analysis to discuss the uptake mechanism. Basically, these results demonstrated that AF-MCS prepared in this work has shown its merit in effective removal of Cr(VI) and rapid separation from effluents simultaneously. PMID:25690680

  13. Assessing Late Cardiopulmonary Function in Patients with Repaired Tetralogy of Fallot Using Exercise Cardiopulmonary Function Test and Cardiac Magnetic Resonance

    PubMed Central

    Yang, Ming-Chun; Chen, Chun-An; Chiu, Hsin-Hui; Chen, Ssu-Yuan; Wang, Jou-Kou; Lin, Ming-Tai; Chiu, Shuenn-Nan; Lu, Chun-Wei; Huang, Shu-Chien; Wu, Mei-Hwan

    2015-01-01

    Background Patients with repaired tetralogy of Fallot (TOF) usually experience progressive right ventricle (RV) dysfunction due to pulmonary regurgitation (PR). This could further worsen the cardiopulmonary function. This study aimed to compare the changes in patient exercise cardiopulmonary test and cardiac magnetic resonance imaging, and consider the implication of these changes. Methods Our study examined repaired TOF patients who underwent cardiopulmonary exercise test (CPET) to obtain maximal (peak oxygen consumption, peak VO2) and submaximal parameters (oxygen uptake efficiency plateau, oxygen uptake efficiency plateau (OUEP), and ratio of minute ventilation to carbon dioxide production, VE/VCO2 slope). Additionally, the hemodynamic status was assessed by using cardiac magnetic resonance. Criteria for exclusion included TOF patients with pulmonary atresia, atrioventricular septal defect, or absence of pulmonary valve syndrome. Results We enrolled 158 patients whose mean age at repair was 7.8 ± 9.1 years (range 0.1-49.2 years) and the mean patient age at CPET was 29.5 ± 12.2 years (range 7.0-57.0 years). Severe PR (PR fraction ≥ 40%) in 53 patients, moderate in 55, and mild (PR fraction < 20%) in 50 patients were noted. The mean RV end-diastolic volume index (RVEDVi) was 113 ± 35 ml/m2, with 7 patients observed to have a RVEDVi > 163 ml/m2. The mean left ventricular ejection fraction (LVEF) was 63 ± 8%, left ventricular end-diastolic volume index (LVEDVi) was 65 ± 12 ml/m2, and LVESVi was 25 ± 14 ml/m2. CPET revealed significantly decreased peak VO2 (68.5 ± 14.4% of predicted), and fair OUEP (90.3 ± 14.1% of predicted) and VE/VCO2 slope (27.1 ± 5.3). PR fraction and age at repair were negatively correlated with maximal and submaximal exercise indicators (peak VO2 and OUEP). Left ventricular (LV) function and size were positively correlated with peak VO2 and OUEP. Conclusions The results of CPET showed that patients with repaired TOF had a low

  14. Low-Functioning Autism and Nonsyndromic Intellectual Disability: Magnetic Resonance Imaging (MRI) Findings.

    PubMed

    Erbetta, Alessandra; Bulgheroni, Sara; Contarino, Valeria Elisa; Chiapparini, Luisa; Esposito, Silvia; Annunziata, Silvia; Riva, Daria

    2015-10-01

    Previous neuroradiologic studies reported a high incidence of abnormalities in low-functioning autistic children. In this population, it is difficult to know which abnormality depends on autism itself and which is related to intellectual disability associated with autism. The aim of this study was to evaluate the frequency of neuroradiologic abnormalities in low-functioning autistic children compared to Intellectual Quotient and age-matched nonsyndromic children, using the same set of magnetic resonance imaging (MRI) sequences. MRI was rated as abnormal in 44% of autistic and 54% of children with intellectual disability. The main results were mega cisterna magna in autism and hypoplastic corpus callosum in intellectual disability. These abnormalities are morphologically visible signs of altered brain development. These findings, more frequent than expected, are not specific to the 2 conditions. Although MRI cannot be considered mandatory, it allows an in-depth clinical assessment in nonsyndromic intellectual-disabled and autistic children. PMID:25895913

  15. Recent developments in optimal experimental designs for functional magnetic resonance imaging

    PubMed Central

    Kao, Ming-Hung; Temkit, M'hamed; Wong, Weng Kee

    2014-01-01

    Functional magnetic resonance imaging (fMRI) is one of the leading brain mapping technologies for studying brain activity in response to mental stimuli. For neuroimaging studies utilizing this pioneering technology, there is a great demand of high-quality experimental designs that help to collect informative data to make precise and valid inference about brain functions. This paper provides a survey on recent developments in experimental designs for fMRI studies. We briefly introduce some analytical and computational tools for obtaining good designs based on a specified design selection criterion. Research results about some commonly considered designs such as blocked designs, and m-sequences are also discussed. Moreover, we present a recently proposed new type of fMRI designs that can be constructed using a certain type of Hadamard matrices. Under certain assumptions, these designs can be shown to be statistically optimal. Some future research directions in design of fMRI experiments are also discussed. PMID:25071884

  16. Facile synthesis of boronic acid-functionalized magnetic carbon nanotubes for highly specific enrichment of glycopeptides

    NASA Astrophysics Data System (ADS)

    Ma, Rongna; Hu, Junjie; Cai, Zongwei; Ju, Huangxian

    2014-02-01

    A stepwise strategy was developed to synthesize boronic acid functionalized magnetic carbon nanotubes (MCNTs) for highly specific enrichment of glycopeptides. The MCNTs were synthesized by a solvothermal reaction of Fe3+ loaded on the acid-treated CNTs and modified with 1-pyrenebutanoic acid N-hydroxysuccinimidyl ester (PASE) to bind aminophenylboronic acid (APBA) via an amide reaction. The introduction of PASE could bridge the MCNT and APBA, suppress the nonspecific adsorption and reduce the steric hindrance among the bound molecules. Due to the excellent structure of the MCNTs, the functionalization of PASE and then APBA on MCNTs was quite simple, specific and effective. The glycopeptides enrichment and separation with a magnetic field could be achieved by their reversible covalent binding with the boronic group of APBA-MCNTs. The exceptionally large specific surface area and the high density of boronic acid groups of APBA-MCNTs resulted in rapid and highly efficient enrichment of glycopeptides, even in the presence of large amounts of interfering nonglycopeptides. The functional MCNTs possessed high selectivity for enrichment of 21 glycopeptides from the digest of horseradish peroxidase demonstrated by MALDI-TOF mass spectrometric analysis showing more glycopeptides detected than the usual 9 glycopeptides with commercially available APBA-agarose. The proposed system showed better specificity for glycopeptides even in the presence of non-glycopeptides with 50 times higher concentration. The boronic acid functionalized MCNTs provide a promising selective enrichment platform for precise glycoproteomic analysis.A stepwise strategy was developed to synthesize boronic acid functionalized magnetic carbon nanotubes (MCNTs) for highly specific enrichment of glycopeptides. The MCNTs were synthesized by a solvothermal reaction of Fe3+ loaded on the acid-treated CNTs and modified with 1-pyrenebutanoic acid N-hydroxysuccinimidyl ester (PASE) to bind aminophenylboronic acid

  17. Functional magnetic resonance imaging of category-specific cortical activation: evidence for semantic maps.

    PubMed

    Spitzer, M; Kischka, U; Gückel, F; Bellemann, M E; Kammer, T; Seyyedi, S; Weisbrod, M; Schwartz, A; Brix, G

    1998-04-01

    Functional magnetic resonance imaging (fMRI) was used to examine the pattern of cortical activity during a picture naming task. Subjects (n=12) had to covertly name either animals or furniture items. Functional scanning was performed using a conventional 1.5-Tesla whole-body MRI system. Images obtained during naming the two categories were compared using a non-parametric test. The study revealed evidence for domain-specific lexical regions in left middle, right middle and inferior frontal areas, as well as in superior and middle temporal areas. The results corroborate neuropsychological data and demonstrate directly and non-invasively in human volunteers that semantic representations in frontal and temporal areas are, to some degree, localized and possibly implemented as multiple maps. A completely distributed storage of semantic information is rendered unlikely. PMID:9593960

  18. Liquid Crystalline Block Copolymers with Brush Type Architecture: Toward Functional Membranes by Magnetic Field Alignment

    NASA Astrophysics Data System (ADS)

    Choo, Youngwoo; Gopinadhan, Manesh; Mahajan, Lalit; Kasi, Rajeswari; Osuji, Chinedum

    2015-03-01

    We introduce a novel liquid crystalline block copolymer with brush type architecture for membrane applications by magnetic field directed self-assembly. Ring-opening metathesis of n-alkyloxy cyanobiphenyl and polylactide (PLA) functionalized norbornene monomers provides efficient polymerization yielding low polydispersity block copolymers. The molecular weight of the PLA side chains, spacer length of the cyanobiphenyl mesogens are systematically varied to form well-ordered BCP morphologies at varying volume fractions. Interestingly, the system features morphology dependent anchoring condition where mesogens adopt planar anchoring on cylindrical interface while homeotropic anchoring was preferred on a planar block interface. The minority PLA domains from highly aligned materials can be readily degraded by hydrolysis to produce vertically aligned nanoporous polymer films which exhibit reversible thermal switching behavior. The polymers introduced here provide a versatile platform for scalable fabrication of aligned membranes and further functional materials based on such templates. This work was supported by NSF(CCMI-1246804).

  19. Magnetically induced behaviour of ferritin corpuscles in avian ears: can cuticulosomes function as magnetosomes?

    PubMed Central

    Jandacka, Petr; Burda, Hynek; Pistora, Jaromir

    2015-01-01

    Magnetoreception is an enigmatic, poorly understood sensory ability, described mainly on the basis of behavioural studies in animals of diverse taxa. Recently, corpuscles containing superparamagnetic iron-storage protein ferritin were found in the inner ear hair cells of birds, a predominantly single ferritin corpuscle per cell. It was suggested that these corpuscles might represent magnetosomes and function as magnetosensors. Here we determine ferritin low-field paramagnetic susceptibility to estimate its magnetically induced intracellular behaviour. Physical simulations show that ferritin corpuscles cannot be deformed or rotate in weak geomagnetic fields, and thus cannot provide magnetoreception via deformation of the cuticular plate. Furthermore, we reached an alternative hypothesis that ferritin corpuscle in avian ears may function as an intracellular electromagnetic oscillator. Such an oscillator would generate additional cellular electric potential related to normal cell conditions. Though the phenomenon seems to be weak, this effect deserves further analyses. PMID:25551148

  20. Controlled surface functionality of magnetic nanoparticles by layer-by-layer assembled nano-films

    NASA Astrophysics Data System (ADS)

    Choi, Daheui; Son, Boram; Park, Tai Hyun; Hong, Jinkee

    2015-04-01

    Over the past several years, the preparation of functionalized nanoparticles has been aggressively pursued in order to develop desired structures, compositions, and structural order. Among the various nanoparticles, iron oxide magnetic nanoparticles (MNPs) have shown great promise because the material generated using these MNPs can be used in a variety of biomedical applications and possible bioactive functionalities. In this study, we report the development of various functionalized MNPs (F-MNPs) generated using the layer-by-layer (LbL) self-assembly method. To provide broad functional opportunities, we fabricated F-MNP bio-toolbox by using three different materials: synthetic polymers, natural polymers, and carbon materials. Each of these F-MNPs displays distinct properties, such as enhanced thickness or unique morphologies. In an effort to explore their biomedical applications, we generated basic fibroblast growth factor (bFGF)-loaded F-MNPs. The bFGF-loaded F-MNPs exhibited different release mechanisms and loading amounts, depending on the film material and composition order. Moreover, bFGF-loaded F-MNPs displayed higher biocompatibility and possessed superior proliferation properties than the bare MNPs and pure bFGF, respectively. We conclude that by simply optimizing the building materials and the nanoparticle's film composition, MNPs exhibiting various bioactive properties can be generated.Over the past several years, the preparation of functionalized nanoparticles has been aggressively pursued in order to develop desired structures, compositions, and structural order. Among the various nanoparticles, iron oxide magnetic nanoparticles (MNPs) have shown great promise because the material generated using these MNPs can be used in a variety of biomedical applications and possible bioactive functionalities. In this study, we report the development of various functionalized MNPs (F-MNPs) generated using the layer-by-layer (LbL) self-assembly method. To provide

  1. Biocompatible polyurethane/thiacalix[4]arenes functionalized Fe3O4 magnetic nanocomposites: Synthesis and properties.

    PubMed

    Mohammadi, Abbas; Barikani, Mehdi; Lakouraj, Moslem Mansour

    2016-09-01

    In this study, a series of magnetic polyurethane/Fe3O4 elastomer nanocomposites were prepared by covalently embedding novel thiacalix[4]arenes (TC4As) functionalized Fe3O4 nanoparticles (TC4As-Fe3O4) which contain macrocycles with reactive hydroxyl groups. Surface functionalization of Fe3O4 nanoparticles with TC4As macrocycles as unique reactive surface modifier not only gives specific characteristics to Fe3O4 nanoparticles but also improves the interphase interaction between nanoparticles and the polyurethane matrices through covalent attachment of polymer chains to nanoparticle surfaces. The novel synthesized TC4As-Fe3O4 nanoparticles were characterized by FTIR, XRD, TGA, VSM and SEM analysis. Furthermore, the effect of functionalization of Fe3O4 nanoparticles on the various properties of resulting nanocomposites was studied by XRD, TGA, DMTA, SEM, and a universal tensile tester. It was found that the functionalization of nanoparticles with TC4As affords better mechanical and thermal properties to polyurethane nanocomposites in comparison with unmodified nanoparticles. The SEM analysis showed finer dispersion of TC4As-Fe3O4 nanoparticles than unmodified Fe3O4 nanoparticles within the polyurethane matrices, which arising from formation of covalent bonding between TC4As functionalized Fe3O4 nanoparticles and polyurethane matrices. Moreover, the investigation of in vitro biocompatibility of novel nanocomposites showed that these samples are excellent candidate for biomedical use. PMID:27207044

  2. Repetitive magnetic stimulation improves retinal function in a rat model of retinal dystrophy

    NASA Astrophysics Data System (ADS)

    Rotenstreich, Ygal; Tzameret, Adi; Levi, Nir; Kalish, Sapir; Sher, Ifat; Zangen, Avraham; Belkin, Michael

    2014-02-01

    Vision incapacitation and blindness associated with retinal dystrophies affect millions of people worldwide. Retinal degeneration is characterized by photoreceptor cell death and concomitant remodeling of remaining retinal cells. Repetitive Magnetic Stimulation (RMS) is a non-invasive technique that creates alternating magnetic fields by brief electric currents transmitted through an insulated coil. These magnetic field generate action potentials in neurons, and modulate the expression of neurotransmitter receptors, growth factors and transcription factors which mediate plasticity. This technology has been proven effective and safe in various psychiatric disorders. Here we determined the effect of RMS on retinal function in Royal College of Surgeons (RCS) rats, a model for retinal dystrophy. Four week-old RCS and control Spargue Dawley (SD) rats received sham or RMS treatment over the right eye (12 sessions on 4 weeks). RMS treatment at intensity of at 40% of the maximal output of a Rapid2 stimulator significantly increased the electroretinogram (ERG) b-wave responses by up to 6- or 10-fold in the left and right eye respectively, 3-5 weeks following end of treatment. RMS treatment at intensity of 25% of the maximal output did not significant effect b-wave responses following end of treatment with no adverse effect on ERG response or retinal structure of SD rats. Our findings suggest that RMS treatment induces delayed improvement of retinal functions and may induce plasticity in the retinal tissue. Furthermore, this non-invasive treatment may possibly be used in the future as a primary or adjuvant treatment for retinal dystrophy.

  3. Lateral flow biosensor for multiplex detection of nitrofuran metabolites based on functionalized magnetic beads.

    PubMed

    Lu, Xuewen; Liang, Xiaoling; Dong, Jianghong; Fang, Zhiyuan; Zeng, Lingwen

    2016-09-01

    The use of potential mutagenic nitrofuran antibiotic in food animal production has been banned world-wide. Common methods for nitrofuran detection involve complex extraction procedures. In the present study, magnetic beads functionalized with antibody against nitrofuran derivative were used as both the extraction and color developing media in lateral flow biosensor. Derivatization reagent carboxybenzaldehyde is firstly modified with ractopamine. After reaction with nitrofuran metabolites, the resultant molecule has two functional groups: the metabolite moiety and the ractopamine moiety. Metabolite moiety is captured by the antibody that is coated on magnetic beads. This duplex is then loaded onto biosensor and ractopamine moiety is further captured by the antibody immobilized on the test zone of nitrocellulose membrane. Without tedious organic reagent-based extraction procedure, this biosensor was capable of visually detecting four metabolites simultaneously with a detection limit of 0.1 μg/L. No cross-reactivity was observed in the presence of 50 μg/L interferential components. Graphical abstract Derivatization of nitrofuran metabolites (AHD, AOZ, SEM, or AMOZ) and LFA detection of the derivative products. PMID:27438720

  4. Magnetic Hydrogels from Alkyne/Cobalt Carbonyl-Functionalized ABA Triblock Copolymers.

    PubMed

    Jiang, Bingyin; Hom, Wendy L; Chen, Xianyin; Yu, Pengqing; Pavelka, Laura C; Kisslinger, Kim; Parise, John B; Bhatia, Surita R; Grubbs, Robert B

    2016-04-01

    A series of alkyne-functionalized poly(4-(phenylethynyl)styrene)-block-poly(ethylene oxide)-block-poly(4-(phenylethynyl)styrene) (PPES-b-PEO-b-PPES) ABA triblock copolymers was synthesized by reversible addition-fragmentation chain transfer (RAFT) polymerization. PESn[Co2(CO)6]x-EO800-PESn[Co2(CO)6]x ABA triblock copolymer/cobalt adducts (10-67 wt % PEO) were subsequently prepared by reaction of the alkyne-functionalized PPES block with Co2(CO)8 and their phase behavior was studied by TEM. Heating triblock copolymer/cobalt carbonyl adducts at 120 °C led to cross-linking of the PPES/Co domains and the formation of magnetic cobalt nanoparticles within the PPES/Co domains. Magnetic hydrogels could be prepared by swelling the PEO domains of the cross-linked materials with water. Swelling tests, rheological studies and actuation tests demonstrated that the water capacity and modulus of the hydrogels were dependent upon the composition of the block copolymer precursors. PMID:26958699

  5. Magnetic nanoparticles coated with maltose-functionalized polyethyleneimine for highly efficient enrichment of N-glycopeptides.

    PubMed

    Li, Jinan; Wang, Fangjun; Wan, Hao; Liu, Jing; Liu, Zheyi; Cheng, Kai; Zou, Hanfa

    2015-12-18

    Hydrophilic interaction chromatography (HILIC) adsorbents have drawn increasing attention in recent years due to their high efficiency in N-glycopeptides enrichment. The hydrophilicity and binding capacity of HILIC adsorbents are crucial to the enrichment efficiency and mass spectrometry (MS) detection sensitivity of N-glycopeptides. Herein, magnetic nanoparticles coated with maltose-functionalized polyethyleneimine (Fe3O4-PEI-Maltose MNPs) were prepared by one-pot solvothermal reaction coupled with "click chemistry" and utilized for N-glycopeptides enrichment. Owing to the presence of hydrophilic and branched polyethyleneimine, the amount of immobilized disaccharide units was improved about four times. The N-glycopeptides capturing capacity was about 150mg/g (IgG/MNPs) and the MS detection limitation as low as 0.5fmol for IgG and 85% average enrichment recovery were feasibly achieved by using this hybrid magnetic adsorbent. Finally, 1237 unique N-glycosylation sites and 1567 unique N-glycopeptides from 684 N-glycoproteins were reliably characterized from 60μg protein sample extracted from mouse liver. Therefore, this maltose-functionalized polyethyleneimine coated adsorbent can play a promising role in highly efficient N-glycopeptides enrichment for glycoproteomic analyses of complex protein samples. PMID:26607318

  6. Comprehensive language mapping in children, using functional magnetic resonance imaging: what's missing counts.

    PubMed

    Wilke, Marko; Lidzba, Karen; Staudt, Martin; Buchenau, Karin; Grodd, Wolfgang; Krägeloh-Mann, Ingeborg

    2005-06-21

    Noninvasive language mapping is a frequently used application of functional magnetic resonance imaging. The examination of children, however, poses both practical and technical challenges. To this effect, we have developed two new paradigms mainly requiring passive listening to stories from which several key words were removed. Results were compared with a standard active verb-generation task, particularly with regard to hemispheric dominance in frontal brain areas. Fifteen healthy children (seven boys, eight girls, 6-14 years) were scanned. Distinct frontal activation was seen in our new tasks, which was stronger when the tasks were analyzed specifically with regard to the missing words. This confirms the hypothesis that the removal of these words is the key in inducing frontal activation. Frontal lateralization was consistent and strong in all three paradigms. Additionally, receptive language areas are also mapped by our new tasks. We conclude that our two new, child-friendly functional magnetic resonance imaging paradigms are useful in determining hemispheric dominance for language in children too young or too impaired to execute an active task. They also allow robust mapping of receptive language areas. PMID:15931061

  7. Magnetic resonance imaging of the congenital clubfoot treated with the French functional (physical therapy) method.

    PubMed

    Richards, B Stephens; Dempsey, Molly

    2007-03-01

    The purpose of this study was to assess magnetic resonance imaging (MRI) changes that occur in clubfeet after nonoperative treatment with the French functional method, specifically pertaining to the chondro-osseous anatomy and the joint relationships. The magnetic resonance images were obtained in 6 infants before treatment and 3 months later. The MRI protocol described previously for clubfeet which were treated by the Ponseti method (J Pediatr Orthop. 2001;21:719) was closely adhered to, except that no sedation was allowed by our institutional review board. The severity of the clubfoot deformities before treatment made assessment of the tibiotalar, talonavicular, and talocalcaneal joint relationships difficult in some feet. Despite this, improvements were noted after treatment in tibiotalar plantarflexion, the talonavicular relationship, the calcaneocuboid relationship, and the varus position of the calcaneus. The wedge shape of both the navicular and distal end of the calcaneus that occasionally was noted on the MRI before treatment improved after therapy. Although improved clinically, persistent equinus of the calcaneus on MRI was significant in 2 feet and was associated with slight dorsal displacement of the cuboid on the calcaneus (MRI evidence of rocker bottom). As noted with use of the Ponseti nonoperative treatment method, the chondro-osseous abnormalities seen on MRI studies in congenital clubfoot improve after treatment with the French functional (physical therapy) method, with the exception of equinus. PMID:17314649

  8. Functionalized magnetic nanoparticles for the decontamination of water polluted with cesium

    NASA Astrophysics Data System (ADS)

    Helal, Ahmed S.; Decorse, Philippe; Perruchot, Christian; Novak, Sophie; Lion, Claude; Ammar, Souad; El Hage Chahine, Jean-Michel; Hémadi, Miryana

    2016-05-01

    Magnetic nanoparticles are attracting considerable interest because of their potential applications in practically all fields of science and technology, including the removal of heavy metals from contaminated waters. It is, therefore, of great importance to adapt the surfaces of these nanoparticles according to the application. In this work advanced nanoparticles (NPs) with well-tailored surface functionalities were synthesized using the polyol method. The efficiency of a chelating agent, succinyl-β-cyclodextrin (SBCD), was first investigated spectrophotometrically and by Isothermal Titration Calorimetry (ITC). SBCD was then grafted onto nanoparticles previously functionalized with 3-aminopropyl triethoxsilane (NP-APTES). The resulting NP-SBCD system was then incubated with a solution of cesium. After magnetic separation, the solid residue was removed from the supernatant and characterized by X-Ray Photoelectron spectrometry (XPS), X-Ray Fluorescence spectrometry (XRF) and Superconducting QUantum Interference Device (SQUID) magnetometry. These characterizations show the presence of cesium in the solid residue, which indicates Cs uptake by the NP-SBCD system. This nanohybrid system constitutes a promising model for heavy metal decontamination.

  9. Comparison of three magnetic bead surface functionalities for RNA extraction and detection.

    PubMed

    Adams, Nicholas M; Bordelon, Hali; Wang, Kwo-Kwang A; Albert, Laura E; Wright, David W; Haselton, Frederick R

    2015-03-25

    Magnetic beads are convenient for extracting nucleic acid biomarkers from biological samples prior to molecular detection. These beads are available with a variety of surface functionalities designed to capture particular subsets of RNA. We hypothesized that bead surface functionality affects binding kinetics, processing simplicity, and compatibility with molecular detection strategies. In this report, three magnetic bead surface chemistries designed to bind nucleic acids, silica, oligo (dT), and a specific oligonucleotide sequence were evaluated. Commercially available silica-coated and oligo (dT) beads, as well as beads functionalized with oligonucleotides complementary to respiratory syncytial virus (RSV) nucleocapsid gene, respectively recovered ∼75, ∼71, and ∼7% target RSV mRNA after a 1 min of incubation time in a surrogate patient sample spiked with the target. RSV-specific beads required much longer incubation times to recover amounts of the target comparable to the other beads (∼77% at 180 min). As expected, silica-coated beads extracted total RNA, oligo (dT) beads selectively extracted total mRNA, and RSV-specific beads selectively extracted RSV N gene mRNA. The choice of bead functionality is generally dependent on the target detection strategy. The silica-coated beads are most suitable for applications that require nucleic acids other than mRNA, especially with detection strategies that are tolerant of a high concentration of nontarget background nucleic acids, such as RT-PCR. On the other hand, oligo (dT) beads are best-suited for mRNA targets, as they bind biomarkers rapidly, have relatively high recovery, and enable detection strategies to be performed directly on the bead surface. Sequence-specific beads may be best for applications that are not tolerant of a high concentration of nontarget nucleic acids that require short RNA sequences without poly(A) tails, such as microRNAs, or that perform RNA detection directly on the bead surface. PMID

  10. Active form Notch4 promotes the proliferation and differentiation of 3T3-L1 preadipocytes

    SciTech Connect

    Lai, Peng-Yeh; Tsai, Chong-Bin; Department of Ophthalmology, Chiayi Christian Hospital, Chiayi 600, Taiwan, ROC ; Tseng, Min-Jen

    2013-01-18

    Highlights: ► Notch4IC modulates the ERK pathway and cell cycle to promote 3T3-L1 proliferation. ► Notch4IC facilitates 3T3-L1 differentiation by up-regulating proadipogenic genes. ► Notch4IC promotes proliferation during the early stage of 3T3-L1 adipogenesis. ► Notch4IC enhances differentiation during subsequent stages of 3T3-L1 adipogenesis. -- Abstract: Adipose tissue is composed of adipocytes, which differentiate from precursor cells in a process called adipogenesis. Many signal molecules are involved in the transcriptional control of adipogenesis, including the Notch pathway. Previous adipogenic studies of Notch have focused on Notch1 and HES1; however, the role of other Notch receptors in adipogenesis remains unclear. Q-RT-PCR analyses showed that the augmentation of Notch4 expression during the differentiation of 3T3-L1 preadipocytes was comparable to that of Notch1. To elucidate the role of Notch4 in adipogenesis, the human active form Notch4 (N4IC) was transiently transfected into 3T3-L1 cells. The expression of HES1, Hey1, C/EBPδ and PPARγ was up-regulated, and the expression of Pref-1, an adipogenic inhibitor, was down-regulated. To further characterize the effect of N4IC in adipogenesis, stable cells expressing human N4IC were established. The expression of N4IC promoted proliferation and enhanced differentiation of 3T3-L1 cells compared with those of control cells. These data suggest that N4IC promoted proliferation through modulating the ERK pathway and the cell cycle during the early stage of 3T3-L1 adipogenesis and facilitated differentiation through up-regulating adipogenic genes such as C/EBPα, PPARγ, aP2, LPL and HSL during the middle and late stages of 3T3-L1 adipogenesis.

  11. Effect of the double-counting functional on the electronic and magnetic properties of half-metallic magnets using the GGA+U method

    NASA Astrophysics Data System (ADS)

    Tsirogiannis, Christos; Galanakis, Iosif

    2015-11-01

    Methods based on the combination of the usual density functional theory (DFT) codes with the Hubbard models are widely used to investigate the properties of strongly correlated materials. Using first-principle calculations we study the electronic and magnetic properties of 20 half-metallic magnets performing self-consistent GGA+U calculations using both the atomic-limit (AL) and around-mean-field (AMF) functionals for the double counting term, used to subtract the correlation part from the DFT total energy, and compare these results to the usual generalized-gradient-approximation (GGA) calculations. Overall the use of AMF produces results similar to the GGA calculations. On the other hand the effect of AL is diversified depending on the studied material. In general the AL functional produces a stronger tendency towards magnetism leading in some cases to unphysical electronic and magnetic properties. Thus the choice of the adequate double-counting functional is crucial for the results obtained using the GGA+U method.

  12. Effects function analysis of ELF magnetic field exposure in the electric utility work environment.

    PubMed

    Zhang, J; Nair, I; Sahl, J

    1997-01-01

    The incomplete understanding of the relation between power-frequency fields and biological responses raises problems in defining an appropriate metric for exposure assessment and epidemiological studies. Based on evidence from biological experiments, one can define alternative metrics or effects functions that embody the relationship between field exposure patterns and hypothetical health effects. In this paper, we explore the application of the "effects function" approach to occupational exposure data. Our analysis provides examples of exposure assessments based on a range of plausible effects functions. An EMDEX time series data set of ELF frequency (40-800 Hz) magnetic field exposure measurements for electric utility workers was analyzed with several statistical measures and effects functions: average field strength, combination of threshold and exposure duration, and field strength changes. Results were compared for eight job categories: electrician, substation operator, machinist, welder, plant operator, lineman/splicer, meter reader, and clerical. Average field strength yields a different ranking for these job categories than the ranks obtained using other biologically plausible effects functions. Whereas the group of electricians has the highest exposure by average field strength, the group of substation operators has the highest ranking for most of the other effects functions. Plant operators rank highest in the total number of field strength changes greater than 1 microT per hour. The clerical group remains at the lowest end for all of these effects functions. Our analysis suggests that, although average field strength could be used as a surrogate of field exposure for simply classifying exposure into "low" and "high," this summary measure may be misleading in the relative ranking of job categories in which workers are in "high" fields. These results indicate the relevance of metrics other than average field strength in occupational exposure assessment and

  13. A Resting State Functional Magnetic Resonance Imaging Study of Concussion in Collegiate Athletes

    PubMed Central

    Czerniak, Suzanne M; Sikoglu, Elif M; Navarro, Ana A Liso; McCafferty, Joseph; Eisenstock, Jordan; Stevenson, J Herbert; King, Jean A; Moore, Constance M

    2015-01-01

    Sports-related concussions are currently diagnosed through multi-domain assessment by a medical professional and may utilize neurocognitive testing as an aide. However, these tests have only been able to detect differences in the days to week post-concussion. Here, we investigate a measure of brain function, namely resting state functional connectivity, which may detect residual brain differences in the weeks to months after concussion. Twenty-one student athletes (9 concussed within 6 months of enrollment; 12 non-concussed; between ages 18 to 22 years) were recruited for this study. All participants completed the Wisconsin Card Sort Task and the Color-Word Interference Test. Neuroimaging data, specifically resting state functional Magnetic Resonance Imaging data, were acquired to examine resting state functional connectivity. Two sample t-tests were used to compare the neurocognitive scores and resting state functional connectivity patterns among concussed and non-concussed participants. Correlations between neurocognitive scores and resting state functional connectivity measures were also determined across all subjects. There were no significant differences in neurocognitive performance between concussed and non-concussed groups. Concussed subjects had significantly increased connections between areas of the brain that underlie executive function. Across all subjects, better neurocognitive performance corresponded to stronger brain connectivity. Even at rest, brains of concussed athletes may have to ‘work harder’ than their healthy peers to achieve similar neurocognitive results. Resting state brain connectivity may be able to detect prolonged brain differences in concussed athletes in a more quantitative manner than neurocognitive test scores. PMID:25112544

  14. Ketoprofen S(+) enantiomer inhibits prostaglandin production and cell growth in 3T6 fibroblast cultures.

    PubMed

    Sánchez, T; Moreno, J J

    1999-04-01

    The ketoprofen S(+) enantiomer inhibits with great stereoselectivity both prostaglandin H synthase isoenzymes. Thus, the biological effects of ketoprofen on inflammation are due almost entirely to the S(+) isomer. Here, we report that the S(+) enantiomer, at doses that inhibit prostaglandin synthesis, is effective in reducing DNA synthesis and 3T6 fibroblast growth. Our data suggest that prostaglandins are involved in the control of 3T6 fibroblast growth and that the effect of the ketoprofen S(+) enantiomer on 3T6 proliferation is correlated with its effects on prostaglandin H synthase and prostaglandin production. PMID:10323281

  15. Optimization of Coronary Whole-Heart MRA Free Breathing Technique at 3T

    PubMed Central

    Gharib, Ahmed M.; Abd-Elmoniem, Khaled Z.; Herzka, Daniel A.; Ho, Vincent B.; Locklin, Julie; Tzatha, Efstathia; Stuber, Matthias; Pettigrew, Roderic I

    2011-01-01

    Four different techniques for 3T whole-heart coronary MRA using free-breathing 3D segmented parallel imaging and adiabatic T2-Prep were assessed. Coronary MRA at 3T is improved by shortening the acquisition window more than employing the highest spatial resolution. Double oblique whole-heart acquisitions result in better overall image quality and allow for better delineation of the LAD. It is possible to attain shorter acquisition windows and a smaller voxel size at 3T than previously reported at 1.5T. PMID:21871751

  16. On (2,3,t)-generations for the Conway group Co1

    NASA Astrophysics Data System (ADS)

    Ali, Faryad

    2013-09-01

    It is well known that all sporadic simple groups are (2,3,t)-generated, with the exception of M11, M22, M23 and McL. A group G is said to be (2,3,t)-generated if it can be generated by an involution x and an element y of order 3 such that o(xy) = t. In the present article, we investigate all (2,3,t)-generations for the Conway's first sporadic simple group Co1, where t is any odd divisor of |Co1|. Computations are carried out with the aid of computer algebra system GAP-Groups, Algorithms and Programming.

  17. Normal-appearing brain tissue analysis in radiologically isolated syndrome using 3 T MRI.

    PubMed

    Labiano-Fontcuberta, Andrés; Mato-Abad, Virginia; Álvarez-Linera, Juan; Hernández-Tamames, Juan Antonio; Martínez-Ginés, María Luisa; Aladro, Yolanda; Ayuso, Lucía; Domingo-Santos, Ángela; Benito-León, Julián

    2016-07-01

    To date, it remains largely unknown whether there is in radiologically isolated syndrome (RIS) brain damage beyond visible T2 white matter lesions. We used single- voxel proton magnetic resonance spectroscopy and diffusion tensor imaging (3 T MRI) to analyze normal-appearing brain tissue regions in 18 RIS patients and 18 matched healthy controls. T2-hyperintense lesion volumes and structural brain volumes were also measured. The absolute metabolite concentrations and ratios of total N-acetylaspartate+N-acetylaspartyl glutamate (NAA), choline-containing compounds, myoinositol, and glutamine-glutamate complex to creatine were calculated. Spectral analysis was performed by LCModel. Voxelwise morphometry analysis was performed to localize regions of brain tissue showing significant changes of fractional anisotropy or mean diffusivity. Compared with healthy controls, RIS patients did not show any significant differences in either the absolute concentration of NAA or NAA/Cr ratio in mid-parietal gray matter. A trend toward lower NAA concentrations (-3.35%) was observed among RIS patients with high risk for conversion to multiple sclerosis. No differences in the other metabolites or their ratios were observed. RIS patients showed lower fractional anisotropy only in clusters overlapping lesional areas, namely in the cingulate gyrus bilaterally and the frontal lobe subgyral bilaterally (P < 0.001). Normalized brain and cortical volumes were significantly lower in RIS patients than in controls (P = 0.01 and P = 0.03, respectively). Our results suggest that in RIS, global brain and cortical atrophy are not primarily driven by significant occult microstructural normal appearing brain damage. Longitudinal MRI studies are needed to better understand the pathological processes underlying this novel entity. PMID:27399108

  18. 3T MR Spectroscopy Reveals an Imbalance between Excitatory and Inhibitory Neurotransmitters in Amyotrophic Lateral Sclerosis

    PubMed Central

    Foerster, Bradley R.; Pomper, Martin G.; Callaghan, Brian C.; Petrou, Myria; Edden, Richard A.E.; Mohamed, Mona A.; Welsh, Robert C.; Carlos, Ruth C.; Barker, Peter B.; Feldman, Eva L.

    2015-01-01

    Objective To determine whether there are reductions in γ-aminobutyric acid (GABA) and elevations of glutamate + glutamine (Glx) levels in different brain regions of patients with amyotrophic lateral sclerosis (ALS) using proton magnetic resonance spectroscopy (1H-MRS). Design 3T short echo time and GABA-edited 1H-MRS centered on the left motor cortex and left subcortical white matter. Short echo time 1H-MRS was also performed centered on the pons. Data were analyzed using logistic regression, t-tests, and Pearson correlations. Post hoc analyses were performed to investigate differences between riluzole-naïve and riluzole-treated ALS patients. Participants Twenty-nine ALS patients and thirty age- and gender-matched healthy controls (HCs). Results ALS patients had significantly lower levels of GABA in the motor cortex compared to HCs (P<.01). ALS patients also had significantly lower levels of N-acetylaspartate in the motor cortex (P<.01), subcortical white matter (P<.05), and pons (P<.01) and higher levels of myo-inositol in the motor cortex (P<.001) and subcortical white matter (P<.01) compared to HCs. Compared to riluzole-treated ALS patients, riluzole-naïve ALS patients had higher levels of Glx in the motor cortex (P<.05) and pons (P<.01), higher levels of creatine in the motor cortex (P<.001) and subcortical white matter (P=.05), and higher levels of N-acetylaspartate in the motor cortex (P<.01). Conclusion There are reduced levels of GABA in the motor cortex of ALS patients. There are elevations of Glx in riluzole-naïve ALS patients compared to ALS riluzole-treated patients. These results point to an imbalance between excitatory and inhibitory neurotransmission, contributing to the pathogenesis of ALS. PMID:23797905

  19. Amygdala reactivity to masked negative faces is associated with automatic judgmental bias in major depression: a 3 T fMRI study

    PubMed Central

    Dannlowski, Udo; Ohrmann, Patricia; Bauer, Jochen; Kugel, Harald; Arolt, Volker; Heindel, Walter; Kersting, Anette; Baune, Bernhard T.; Suslow, Thomas

    2007-01-01

    Objective In a previous study, we demonstrated that amygdala reactivity to masked negative facial emotions predicts negative judgmental bias in healthy subjects. In the present study, we extended the paradigm to a sample of 35 inpatients suffering from depression to investigate the effect of amygdala reactivity on automatic negative judgmental bias and clinical characteristics in depression. Methods Amygdala activity was recorded in response to masked displays of angry, sad and happy facial expressions by means of functional magnetic resonance imaging at 3 T. In a subsequent experiment, the patients performed an affective priming task that characterizes automatic emotion processing by investigating the biasing effect of subliminally presented emotional faces on evaluative ratings to subsequently presented neutral stimuli. Results Significant associations between (right) amygdala reactivity and automatic negative judgmental bias were replicated in our patient sample (r = –0.59, p < 0.001). Further, negatively biased evaluative processing was associated with severity and longer course of illness (r = –0.57, p = 0.001). Conclusion Amygdala hyperactivity is a neural substrate of negatively biased automatic emotion processing that could be a determinant for a more severe disease course. PMID:18043766

  20. Magnetic capture from blood rescues molecular motor function in diagnostic nanodevices

    PubMed Central

    2013-01-01

    Background Introduction of effective point-of-care devices for use in medical diagnostics is part of strategies to combat accelerating health-care costs. Molecular motor driven nanodevices have unique potentials in this regard due to unprecedented level of miniaturization and independence of external pumps. However motor function has been found to be inhibited by body fluids. Results We report here that a unique procedure, combining separation steps that rely on antibody-antigen interactions, magnetic forces applied to magnetic nanoparticles (MPs) and the specificity of the actomyosin bond, can circumvent the deleterious effects of body fluids (e.g. blood serum). The procedure encompasses the following steps: (i) capture of analyte molecules from serum by MP-antibody conjugates, (ii) pelleting of MP-antibody-analyte complexes, using a magnetic field, followed by exchange of serum for optimized biological buffer, (iii) mixing of MP-antibody-analyte complexes with actin filaments conjugated with same polyclonal antibodies as the magnetic nanoparticles. This causes complex formation: MP-antibody-analyte-antibody-actin, and magnetic separation is used to enrich the complexes. Finally (iv) the complexes are introduced into a nanodevice for specific binding via actin filaments to surface adsorbed molecular motors (heavy meromyosin). The number of actin filaments bound to the motors in the latter step was significantly increased above the control value if protein analyte (50–60 nM) was present in serum (in step i) suggesting appreciable formation and enrichment of the MP-antibody-analyte-antibody-actin complexes. Furthermore, addition of ATP demonstrated maintained heavy meromyosin driven propulsion of actin filaments showing that the serum induced inhibition was alleviated. Detailed analysis of the procedure i-iv, using fluorescence microscopy and spectroscopy identified main targets for future optimization. Conclusion The results demonstrate a promising approach for

  1. Origins of Highly Structured Distribution Functions in Magnetic Reconnection Exhausts: Understanding Electron Acceleration and Heating

    NASA Astrophysics Data System (ADS)

    Shuster, J. R.; Wang, S.; Chen, L. J.; Bessho, N.; Guo, R.; Torbert, R. B.; Daughton, W. S.

    2014-12-01

    Electron velocity distribution functions (VDFs) during reconnection with negligible guide field from particle in cell (PIC) simulations and Cluster observations are studied to further understand electron acceleration and heating. Until recently, electrons in the exhaust of reconnection with negligible guide field were thought to be isotropic. PIC simulation results with zero guide field reveal that near the time of peak reconnection, VDFs become highly structured in magnetic islands and open exhausts. Ring, arc, and counterstreaming populations are generic and lasting constituents of exhaust electron VDFs. Analyses of particle trajectories indicate that a number of mechanisms including Fermi acceleration, the parallel potential, and adiabatic heating contribute to the energization of exhaust electrons. Near the electron diffusion region (EDR), exhaust electrons exhibit large Te⊥ due to ring and arc populations of electrons accelerated in the EDR. Farther away from the EDR, the VDFs show a mixture of electrons from the EDR and those crossing the separatrix from the inflow. Pitch angle scattering is effective near the exhaust midplane, away from the EDR and before reaching the magnetic pileup region, producing isotropic, high-energy electrons, while the low energy exhaust electrons exhibit the anisotropy Te// > Te⊥ characteristic of the inflow. The work done on the electrons by the perpendicular electric field between the end of EDR and the magnetic pileup region is due to Fermi acceleration which leads to a net increase in the electron's parallel velocity. For the net increase of electrons' v⊥ beyond the EDR, pitch angle scattering effectively converts v// gained by acceleration from the parallel potential into v⊥. Electron's v⊥ further increases downstream through adiabatic heating from the increasing magnetic field in addition to less efficient pitch angle scattering. The parallel potential and the magnetic bottle together determine the trapped

  2. Affinity capture using peptide-functionalized magnetic nanoparticles to target Staphylococcus aureus

    NASA Astrophysics Data System (ADS)

    Kuo, Fang-Yin; Lin, Wei-Lien; Chen, Yu-Chie

    2016-04-01

    Staphylococcus aureus, a commonly found pathogen, can cause food poisoning and infections. Thus, it is necessary to develop analytical methods for the rapid screening of S. aureus in suspicious samples. Magnetic nanoparticles (MNPs) are widely used as affinity probes to selectively enrich target species from complex samples because of their high specific surface area and magnetic properties. The MNP surface should be functionalized to have the capability to target specific species. We herein propose a straightforward method to functionalize aluminum oxide-coated iron oxide (Fe3O4@Al2O3) MNPs with the peptide HHHHHHDEEGLFVD (D). The peptide D was comprised of three domains: polyhistidine (H6) used as the linker, DEE added as the spacer, and GLFVD used for targeting S. aureus. D was immobilized on the surface of Fe3O4@Al2O3 MNPs through H6-Al chelation. Our results showed that the D-functionalized Fe3O4@Al2O3 MNPs (D-Fe3O4 MNPs) possess the capability to target S. aureus. The selective trapping experiments were conducted under microwave-heating for only 60 s, and sufficient bacterial cells were trapped by the MNPs to be identified by matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS). We demonstrated that the D-Fe3O4@Al2O3 MNPs combined with MALDI-MS can be used to rapidly characterize trace amounts of S. aureus in complex juice and egg samples.Staphylococcus aureus, a commonly found pathogen, can cause food poisoning and infections. Thus, it is necessary to develop analytical methods for the rapid screening of S. aureus in suspicious samples. Magnetic nanoparticles (MNPs) are widely used as affinity probes to selectively enrich target species from complex samples because of their high specific surface area and magnetic properties. The MNP surface should be functionalized to have the capability to target specific species. We herein propose a straightforward method to functionalize aluminum oxide-coated iron oxide (Fe3O4@Al2O3) MNPs with the

  3. Visualizing functional pathways in the human brain using correlation tensors and magnetic resonance imaging.

    PubMed

    Ding, Zhaohua; Xu, Ran; Bailey, Stephen K; Wu, Tung-Lin; Morgan, Victoria L; Cutting, Laurie E; Anderson, Adam W; Gore, John C

    2016-01-01

    Functional magnetic resonance imaging usually detects changes in blood oxygenation level dependent (BOLD) signals from T2*-sensitive acquisitions, and is most effective in detecting activity in brain cortex which is irrigated by rich vasculature to meet high metabolic demands. We recently demonstrated that MRI signals from T2*-sensitive acquisitions in a resting state exhibit structure-specific temporal correlations along white matter tracts. In this report we validate our preliminary findings and introduce spatio-temporal functional correlation tensors to characterize the directional preferences of temporal correlations in MRI signals acquired at rest. The results bear a remarkable similarity to data obtained by diffusion tensor imaging but without any diffusion-encoding gradients. Just as in gray matter, temporal correlations in resting state signals may reflect intrinsic synchronizations of neural activity in white matter. Here we demonstrate that functional correlation tensors are able to visualize long range white matter tracts as well as short range sub-cortical fibers imaged at rest, and that evoked functional activities alter these structures and enhance the visualization of relevant neural circuitry. Furthermore, we explore the biophysical mechanisms underlying these phenomena by comparing pulse sequences, which suggest that white matter signal variations are consistent with hemodynamic (BOLD) changes associated with neural activity. These results suggest new ways to evaluate MRI signal changes within white matter. PMID:26477562

  4. Superparamagnetic And Paramagnetic MRI Contrast Agents: Application Of Rapid Magnetic Resonance Imaging To Assess Renal Function

    NASA Astrophysics Data System (ADS)

    Carvlin, Mark J.; Renshaw, Perry F.; Arger, Peter; Kundel, Harold L.; Dougherty, Larry; Axel, Leon; Kassab, Eleanor; Moore, Bethanne

    1988-06-01

    The paramagnetic chelate complex, gadolinium-diethylene-triamine-pentaacetic acid, Gd-DTPA, and superparamagnetic particles, such as those composed of dextran coated magnetite, function as magnetic resonance contrast agents by changing the relaxation rates, 1/T1 and 1/T2. The effects that these agents have upon MR signal intensity are determined by: the inherent biophysical properties of the tissue being imaged, the concentration of the contrast agent and the data acquisition scheme (pulse sequence parameters) employed. Following the time course of MR signal change in the first minutes after the injection of contrast agent(s) allows a dynamic assessment of organ functions in a manner analogous to certain nuclear medicine studies. In order to study renal function, sequential MR fast scan images, gradient echo (TR=35/TE=7 msec, flip angle=25 degrees), were acquired, one every 12 seconds, after intravenous injection of Gd-DTPA and/or dextran-magnetite. Gd-DTPA, which is freely filtered at the glomerulus and is neither secreted nor reabsorbed, provides information concerning renal perfusion, glomerular filtration and tubular concentrating ability. Dextran-magnetite (200 A diameter), which is primarily contained within the intravascular space shortly after injection, provides information on blood flow to and distribution within the kidney. The MR signal change observed after administration of contrast agents varied dramatically depending upon the agents injected and the imaging parameters used. Hence a broad range of physiolgic processes may be described using these techniques, i.e. contrast agent enhanced functional MR examinations.

  5. Visualizing Functional Pathways in the Human Brain Using Correlation Tensors and Magnetic Resonance Imaging

    PubMed Central

    Ding, Zhaohua; Xu, Ran; Bailey, Stephen K.; Wu, Tung-Lin; Morgan, Victoria L.; Cutting, Laurie E.; Anderson, Adam W.; Gore, John C.

    2016-01-01

    Functional magnetic resonance imaging usually detects changes in blood oxygenation level dependent (BOLD) signals from T2*-sensitive acquisitions, and is most effective in detecting activity in brain cortex which is irrigated by rich vasculature to meet high metabolic demands. We recently demonstrated that MRI signals from T2*-sensitive acquisitions in a resting state exhibit structure-specific temporal correlations along white matter tracts. In this report we validate our preliminary findings and introduce spatio-temporal functional correlation tensors to characterize the directional preferences of temporal correlations in MRI signals acquired at rest. The results bear a remarkable similarity to data obtained by diffusion tensor imaging but without any diffusion-encoding gradients. Just as in gray matter, temporal correlations in resting state signals may reflect intrinsic synchronizations of neural activity in white matter. Here we demonstrate that functional correlation tensors are able to visualize long range white matter tracts as well as short range sub-cortical fibers imaged at rest, and that evoked functional activities alter these structures and enhance the visualization of relevant neural circuitry. Furthermore, we explore the biophysical mechanisms underlying these phenomena by comparing pulse sequences, which suggest that white matter signal variations are consistent with hemodynamic (BOLD) changes associated with neural activity. These results suggest new ways to evaluate MRI signal changes within white matter. PMID:26477562

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

    PubMed

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

    2015-07-28

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

  7. Cardiac Structure and Function in Cushing's Syndrome: A Cardiac Magnetic Resonance Imaging Study

    PubMed Central

    Roux, Charles; Salenave, Sylvie; Kachenoura, Nadjia; Raissouni, Zainab; Macron, Laurent; Guignat, Laurence; Jublanc, Christel; Azarine, Arshid; Brailly, Sylvie; Young, Jacques; Mousseaux, Elie; Chanson, Philippe

    2014-01-01

    Background: Patients with Cushing's syndrome have left ventricular (LV) hypertrophy and dysfunction on echocardiography, but echo-based measurements may have limited accuracy in obese patients. No data are available on right ventricular (RV) and left atrial (LA) size and function in these patients. Objectives: The objective of the study was to evaluate LV, RV, and LA structure and function in patients with Cushing's syndrome by means of cardiac magnetic resonance, currently the reference modality in assessment of cardiac geometry and function. Methods: Eighteen patients with active Cushing's syndrome and 18 volunteers matched for age, sex, and body mass index were studied by cardiac magnetic resonance. The imaging was repeated in the patients 6 months (range 2–12 mo) after the treatment of hypercortisolism. Results: Compared with controls, patients with Cushing's syndrome had lower LV, RV, and LA ejection fractions (P < .001 for all) and increased end-diastolic LV segmental thickness (P < .001). Treatment of hypercortisolism was associated with an improvement in ventricular and atrial systolic performance, as reflected by a 15% increase in the LV ejection fraction (P = .029), a 45% increase in the LA ejection fraction (P < .001), and an 11% increase in the RV ejection fraction (P = NS). After treatment, the LV mass index and end-diastolic LV mass to volume ratio decreased by 17% (P < .001) and 10% (P = .002), respectively. None of the patients had late gadolinium myocardial enhancement. Conclusion: Cushing's syndrome is associated with subclinical biventricular and LA systolic dysfunctions that are reversible after treatment. Despite skeletal muscle atrophy, Cushing's syndrome patients have an increased LV mass, reversible upon correction of hypercortisolism. PMID:25093618

  8. Influence of intermittency on the anisotropy of magnetic structure functions of solar wind turbulence

    NASA Astrophysics Data System (ADS)

    Pei, Zhongtian; He, Jiansen; Wang, Xin; Tu, Chuanyi; Marsch, Eckart; Wang, Linghua; Yan, Limei

    2016-02-01

    Intermittency appears to be connected with the spectral anisotropy of solar wind turbulence. We use the Local Intermittency Measure to identify and remove intermittency from the magnetic field data measured by the Ulysses spacecraft in fast solar wind. Structure functions are calculated based on the time sequences as obtained before and after removing intermittency and arranged by time scale (τ) and ΘRB (the angle between local mean magnetic field B0 and radial direction R). Thus, the scaling exponent (ξ(p, ΘRB)) of every structure function of order (p) is obtained for different angles. Before removing intermittency, ξ(p, ΘRB) shows a distinctive dependence on ΘRB: from monofractal scaling law at ΘRB ~0° to multifractal scaling law at ΘRB ~90°. In contrast after eliminating the intermittency, ξ(p, ΘRB) is found to be more monofractal for all ΘRB. The extended structure-function model is applied to ξ(p, ΘRB), revealing differences of its fitting parameters α (a proxy of the power spectral index) and P1 (fragmentation fraction) for the cases with and without intermittency. Parameter α shows an evident angular trend falling from 1.9 to 1.6 for the case with intermittency but has a relatively flat profile around 1.8 for the case without intermittency. Parameter P1 rises from around 0.5 to above 0.8 with increasing ΘRB for the intermittency case and is located between 0.5 and 0.8 for the case lacking intermittency. Therefore, we may infer that it is the anisotropy of intermittency that causes the scaling anisotropy of energy spectra and the unequal fragmentation of energy cascading.

  9. Magnetic Helicity Spectrum of Solar Wind Fluctuations as a Function of the Angle with Respect to the Local Mean Magnetic Field

    NASA Astrophysics Data System (ADS)

    Podesta, J. J.; Gary, S. P.

    2011-06-01

    Magnetic field data acquired by the Ulysses spacecraft in high-speed streams over the poles of the Sun are used to investigate the normalized magnetic helicity spectrum σ m as a function of the angle θ between the local mean magnetic field and the flow direction of the solar wind. This spectrum provides important information about the constituent modes at the transition to kinetic scales that occurs near the spectral break separating the inertial range from the dissipation range. The energetically dominant signal at scales near the thermal proton gyroradius k bottomρ i ~ 1 often covers a wide band of propagation angles centered about the perpendicular direction, θ ~= 90° ± 30°. This signal is consistent with a spectrum of obliquely propagating kinetic Alfvén waves with k bottom Gt k par in which there is more energy in waves propagating away from the Sun and along the direction of the local mean magnetic field than toward the Sun. Moreover, this signal is principally responsible for the reduced magnetic helicity spectrum measured using Fourier transform techniques. The observations also reveal a subdominant population of nearly parallel propagating electromagnetic waves near the proton inertial scale k par c/ωpi ~ 1 that often exhibit high magnetic helicity |σ m | ~= 1. These waves are believed to be caused by proton pressure anisotropy instabilities that regulate distribution functions in the collisionless solar wind. Because of the existence of a drift of alpha particles with respect to the protons, the proton temperature anisotropy instability that operates when T pbottom/T ppar > 1 preferentially generates outward propagating ion-cyclotron waves and the fire-hose instability that operates when T pbottom/T ppar < 1 preferentially generates inward propagating whistler waves. These kinetic processes provide a natural explanation for the magnetic field observations.

  10. MAGNETIC HELICITY SPECTRUM OF SOLAR WIND FLUCTUATIONS AS A FUNCTION OF THE ANGLE WITH RESPECT TO THE LOCAL MEAN MAGNETIC FIELD

    SciTech Connect

    Podesta, J. J.; Gary, S. P.

    2011-06-10

    Magnetic field data acquired by the Ulysses spacecraft in high-speed streams over the poles of the Sun are used to investigate the normalized magnetic helicity spectrum {sigma}{sub m} as a function of the angle {theta} between the local mean magnetic field and the flow direction of the solar wind. This spectrum provides important information about the constituent modes at the transition to kinetic scales that occurs near the spectral break separating the inertial range from the dissipation range. The energetically dominant signal at scales near the thermal proton gyroradius k{sub perpendicular{rho}i} {approx} 1 often covers a wide band of propagation angles centered about the perpendicular direction, {theta} {approx_equal} 90{sup 0} {+-} 30{sup 0}. This signal is consistent with a spectrum of obliquely propagating kinetic Alfven waves with k{sub perpendicular} >> k{sub ||} in which there is more energy in waves propagating away from the Sun and along the direction of the local mean magnetic field than toward the Sun. Moreover, this signal is principally responsible for the reduced magnetic helicity spectrum measured using Fourier transform techniques. The observations also reveal a subdominant population of nearly parallel propagating electromagnetic waves near the proton inertial scale k{sub ||} c/{omega}{sub pi} {approx} 1 that often exhibit high magnetic helicity |{sigma}{sub m}| {approx_equal} 1. These waves are believed to be caused by proton pressure anisotropy instabilities that regulate distribution functions in the collisionless solar wind. Because of the existence of a drift of alpha particles with respect to the protons, the proton temperature anisotropy instability that operates when T{sub pperpendicular}/T{sub p||} > 1 preferentially generates outward propagating ion-cyclotron waves and the fire-hose instability that operates when T{sub pperpendicular}/T{sub p||} < 1 preferentially generates inward propagating whistler waves. These kinetic processes

  11. Magnetism, structures and stabilities of cluster assembled TM@Si nanotubes (TM = Cr, Mn and Fe): a density functional study.

    PubMed

    Dhaka, Kapil; Bandyopadhyay, Debashis

    2016-08-01

    The present study reports transition metal (TM = Cr, Mn and Fe) doped silicon nanotubes with tunable band structures and magnetic properties by careful selection of cluster assemblies as building blocks using the first-principles density functional theory. We found that the transition metal doping and in addition, the hydrogen termination process can stabilize the pure silicon nanoclusters or cluster assemblies and then it could be extended as magnetic nanotubes with finite magnetic moments. Study of the band structures and density of states (DOS) of different empty and TM doped nanotubes (Type 1 to Type 4) show that these nanotubes are useful as metals, semiconductors, semi-metals and half-metals. These designer magnetic materials could be useful in spintronics and magnetic devices of nanoscale order. PMID:27430742

  12. A density functional study of strong local magnetism creation on MoS2 nanoribbon by sulfur vacancy

    NASA Astrophysics Data System (ADS)

    Shidpour, Reza; Manteghian, Merhrdad

    2010-08-01

    In this study a low-width MoS2 ribbon has been used for probing the electronic structure and local magnetic moment near vacancies. A theoretical study with the full-potential Density Functional Theory (DFT) approach (Wien2K code) have shown that when the dimension of MoS2 is reduced from 2-D to 1-D the nonmagnetic semi-conductor MoS2 becomes a magnetic conductor. Our study has shown that a vacancy on the S-edge with 50% coverage intensifies the magnetization of the edge of the MoS2 nanoribbon but such a vacancy on S-edge with 100% coverage causes this magnetic property to disappear. It is concluded that in both of them, there are positive or negative strong gradients of local magnetic moment near the vacancy. This may explain why lattice defects are essential for catalysis processes.

  13. A density functional study of strong local magnetism creation on MoS2 nanoribbon by sulfur vacancy.

    PubMed

    Shidpour, Reza; Manteghian, Merhrdad

    2010-08-01

    In this study a low-width MoS(2) ribbon has been used for probing the electronic structure and local magnetic moment near vacancies. A theoretical study with the full-potential Density Functional Theory (DFT) approach (Wien2K code) have shown that when the dimension of MoS(2) is reduced from 2-D to 1-D the nonmagnetic semi-conductor MoS(2) becomes a magnetic conductor. Our study has shown that a vacancy on the S-edge with 50% coverage intensifies the magnetization of the edge of the MoS(2) nanoribbon but such a vacancy on S-edge with 100% coverage causes this magnetic property to disappear. It is concluded that in both of them, there are positive or negative strong gradients of local magnetic moment near the vacancy. This may explain why lattice defects are essential for catalysis processes. PMID:20820730

  14. MAGNETS

    DOEpatents

    Hofacker, H.B.

    1958-09-23

    This patent relates to nmgnets used in a calutron and more particularly to means fur clamping an assembly of magnet coils and coil spacers into tightly assembled relation in a fluid-tight vessel. The magnet comprises windings made up of an assembly of alternate pan-cake type coils and spacers disposed in a fluid-tight vessel. At one end of the tank a plurality of clamping strips are held firmly against the assembly by adjustable bolts extending through the adjacent wall. The foregoing arrangement permits taking up any looseness which may develop in the assembly of coils and spacers.

  15. Towards an automated selection of spontaneous co-activity maps in functional magnetic resonance imaging

    NASA Astrophysics Data System (ADS)

    Sourty, Marion; Thoraval, Laurent; Roquet, Daniel; Armspach, Jean-Paul; Foucher, Jack

    2015-03-01

    Functional magnetic resonance imaging allows to assess large scale functional integration of the brain. One of the leading techniques to extract functionally relevant networks is spatial independent component analysis (ICA). Spatial ICA separates independent spatial sources, many of whom are noise or imaging artifacts, whereas some do correspond to functionally relevant Spontaneous co-Activity Maps (SAMs). For research purposes, ICA is generally performed on group data. This strategy is well adapted to uncover commonly shared networks, e.g. resting-state networks, but fails to capture idiosyncratic functional networks which may be related to pathological activity, e.g. epilepsy, hallucinations. To capture these subject specific networks, ICA has to be applied to single subjects using a large number of components, from which a tenth are SAMs. Up to now, SAMs have to be selected manually by an expert based on predefined criteria. We aim to semi-automate the selection process in order to save time. To this end, some approaches have been proposed but none with the near 100 % sensitivity required for clinical purposes. In this paper, we propose a computerized version of the SAM's criteria used by experts, based on frequential and spatial characteristics of functional networks. Here we present a pre-selection method and its results at different resolutions, with different scanners or imaging sequences. While preserving a near 100 % sensitivity, it allows an average of 70 % reduction of components to be classified which save 55% of experts' time. In comparison, group ICA fails to detect about 25% of the SAMs.

  16. Prediction of Liver Function by Using Magnetic Resonance-based Portal Venous Perfusion Imaging

    SciTech Connect

    Cao Yue; Wang Hesheng; Johnson, Timothy D.; Pan, Charlie; Hussain, Hero; Balter, James M.; Normolle, Daniel; Ben-Josef, Edgar; Ten Haken, Randall K.; Lawrence, Theodore S.; Feng, Mary

    2013-01-01

    Purpose: To evaluate whether liver function can be assessed globally and spatially by using volumetric dynamic contrast-enhanced magnetic resonance imaging MRI (DCE-MRI) to potentially aid in adaptive treatment planning. Methods and Materials: Seventeen patients with intrahepatic cancer undergoing focal radiation therapy (RT) were enrolled in institution review board-approved prospective studies to obtain DCE-MRI (to measure regional perfusion) and indocyanine green (ICG) clearance rates (to measure overall liver function) prior to, during, and at 1 and 2 months after treatment. The volumetric distribution of portal venous perfusion in the whole liver was estimated for each scan. We assessed the correlation between mean portal venous perfusion in the nontumor volume of the liver and overall liver function measured by ICG before, during, and after RT. The dose response for regional portal venous perfusion to RT was determined using a linear mixed effects model. Results: There was a significant correlation between the ICG clearance rate and mean portal venous perfusion in the functioning liver parenchyma, suggesting that portal venous perfusion could be used as a surrogate for function. Reduction in regional venous perfusion 1 month after RT was predicted by the locally accumulated biologically corrected dose at the end of RT (P<.0007). Regional portal venous perfusion measured during RT was a significant predictor for regional venous perfusion assessed 1 month after RT (P<.00001). Global hypovenous perfusion pre-RT was observed in 4 patients (3 patients with hepatocellular carcinoma and cirrhosis), 3 of whom had recovered from hypoperfusion, except in the highest dose regions, post-RT. In addition, 3 patients who had normal perfusion pre-RT had marked hypervenous perfusion or reperfusion in low-dose regions post-RT. Conclusions: This study suggests that MR-based volumetric hepatic perfusion imaging may be a biomarker for spatial distribution of liver function, which

  17. Prediction of Liver Function by Using Magnetic Resonance-based Portal Venous Perfusion Imaging

    PubMed Central

    Cao, Yue; Wang, Hesheng; Johnson, Timothy D.; Pan, Charlie; Hussain, Hero; Balter, James M.; Normolle, Daniel; Ben-Josef, Edgar; Ten Haken, Randall K.; Lawrence, Theodore S.; Feng, Mary

    2013-01-01

    Purpose To evaluate whether liver function can be assessed globally and spatially by using volumetric dynamic contrast-enhanced magnetic resonance imaging MRI (DCE-MRI) to potentially aid in adaptive treatment planning. Methods and Materials Seventeen patients with intrahepatic cancer undergoing focal radiation therapy (RT) were enrolled in institution review board-approved prospective studies to obtain DCE-MRI (to measure regional perfusion) and indocyanine green (ICG) clearance rates (to measure overall liver function) prior to, during, and at 1 and 2 months after treatment. The volumetric distribution of portal venous perfusion in the whole liver was estimated for each scan. We assessed the correlation between mean portal venous perfusion in the nontumor volume of the liver and overall liver function measured by ICG before, during, and after RT. The dose response for regional portal venous perfusion to RT was determined using a linear mixed effects model. Results There was a significant correlation between the ICG clearance rate and mean portal venous perfusion in the functioning liver parenchyma, suggesting that portal venous perfusion could be used as a surrogate for function. Reduction in regional venous perfusion 1 month after RT was predicted by the locally accumulated biologically corrected dose at the end of RT (P<.0007). Regional portal venous perfusion measured during RT was a significant predictor for regional venous perfusion assessed 1 month after RT (P<.00001). Global hypovenous perfusion pre-RT was observed in 4 patients (3 patients with hepatocellular carcinoma and cirrhosis), 3 of whom had recovered from hypoperfusion, except in the highest dose regions, post-RT. In addition, 3 patients who had normal perfusion pre-RT had marked hypervenous perfusion or reperfusion in low-dose regions post-RT. Conclusions This study suggests that MR-based volumetric hepatic perfusion imaging may be a biomarker for spatial distribution of liver function, which

  18. Antidiabetic thiazolidinediones inhibit leptin (ob) gene expression in 3T3-L1 adipocytes.

    PubMed Central

    Kallen, C B; Lazar, M A

    1996-01-01

    Lack of leptin (ob) protein causes obesity in mice. The leptin gene product is important for normal regulation of appetite and metabolic rate and is produced exclusively by adipocytes. Leptin mRNA was induced during the adipose conversion of 3T3-L1 cells, which are useful for studying adipocyte differentiation and function under controlled conditions. We studied leptin regulation by antidiabetic thiazolidinedione compounds, which are ligands for the adipocyte-specific nuclear receptor peroxisome proliferator-activated receptor gamma (PPARgamma) that regulates the transcription of other adipocyte-specific genes. Remarkably, leptin gene expression was dramatically repressed within a few hours after thiazolidinedione treatment. The ED50 for inhibition of leptin expression by the thiazolidinedione BRL49653 was between 5 and 50 nM, similar to its Kd for binding to PPARgamma. The relatively weak, nonthiazolidinedione PPAR activator WY 14,643 also inhibited leptin expression, but was approximately 1000 times less potent than BRL49653. These results indicate that antidiabetic thiazolidinediones down-regulate leptin gene expression with potencies that correlate with their abilities to bind and activate PPARgamma. Images Fig. 1 Fig. 2 Fig. 3 Fig. 4 PMID:8650171

  19. Manganese superoxide dismutase knock-down in 3T3-L1 preadipocytes impairs subsequent adipogenesis.

    PubMed

    Krautbauer, Sabrina; Eisinger, Kristina; Hader, Yvonne; Neumeier, Markus; Buechler, Christa

    2014-08-01

    Adipogenesis is associated with the upregulation of the antioxidative enzyme manganese superoxide dismutase (MnSOD) suggesting a vital function of this enzyme in adipocyte maturation. In the current work, MnSOD was knocked-down with small-interference RNA in preadipocytes to study its role in adipocyte differentiation. In mature adipocytes differentiated from these cells, proteins characteristic for mature adipocytes, which are strongly induced in late adipogenesis like adiponectin and fatty acid-binding protein 4, are markedly reduced. Triglycerides begin to accumulate after about 6 days of the induction of adipogenesis, and are strongly diminished in cells with low MnSOD. Proteins upregulated early during differentiation, like fatty acid synthase and cytochrome C oxidase-4, are not altered. Cell viability, insulin-mediated phosphorylation of Akt, antioxidative capacity (AOC), superoxide levels, and heme oxygenase 1 with the latter being induced upon oxidative stress are not affected. L-Buthionine-(S,R)-sulfoximine (BSO) depletes glutathione and modestly lowers AOC of mature adipocytes. Addition of BSO to 3T3-L1 cells 3 days after the initiation of differentiation impairs triglyceride accumulation and expression of proteins induced in late adipogenesis. Of note, proteins that increased early during adipogenesis are also diminished, suggesting that BSO causes de-differentiation of these cells. Preadipocyte proliferation is not considerably affected by low MnSOD and BSO. These data suggest that glutathione and MnSOD are essential for adipogenesis. PMID:24740755

  20. Hsp90 chaperones PPARγ and regulates differentiation and survival of 3T3-L1 adipocytes

    PubMed Central

    Nguyen, M T; Csermely, P; Sőti, C

    2013-01-01

    Adipose tissue dysregulation has a major role in various human diseases. The peroxisome proliferator-activated receptor-γ (PPARγ) is a key regulator of adipocyte differentiation and function, as well as a target of insulin-sensitizing drugs. The Hsp90 chaperone stabilizes a diverse set of signaling ‘client' proteins, thereby regulates various biological processes. Here we report a novel role for Hsp90 in controlling PPARγ stability and cellular differentiation. Specifically, we show that the Hsp90 inhibitors geldanamycin and novobiocin efficiently impede the differentiation of murine 3T3-L1 preadipocytes. Geldanamycin at higher concentrations also inhibits the survival of both developing and mature adipocytes, respectively. Further, Hsp90 inhibition disrupts an Hsp90-PPARγ complex, leads to the destabilization and proteasomal degradation of PPARγ, and inhibits the expression of PPARγ target genes, identifying PPARγ as an Hsp90 client. A similar destabilization of PPARγ and a halt of adipogenesis also occur in response to protein denaturing stresses caused by a single transient heat-shock or proteasome inhibition. Recovery from stress restores PPARγ stability and adipocyte differentiation. Thus, our findings reveal Hsp90 as a critical stress-responsive regulator of adipocyte biology and offer a potential therapeutic target in obesity and the metabolic syndrome. PMID:24096869

  1. Differentiation of the insulin-sensitive glucose transporter in 3T3-L1 adipocytes

    SciTech Connect

    Frost, S.C.; Baly, D.L.; Cushman, S.W.; Lane, M.D.; Simpson, I.A.

    1986-05-01

    3T3-L1 fibroblasts differentiate in culture to resemble adipocytes both morphologically and biochemically. Insulin-sensitive glucose transport, as measured by 2-deoxy-(1-/sup 14/C)- glucose uptake in the undifferentiated cell is small (2X). In contrast, the rate of glucose transport in fully differentiated cells is elevated 15-fold over basal in the presence of insulin. To determine if this is due to an increase in the number of transporters/cell or accessibility to the transporters, the number of transporters was measured in subcellular fractions over differentiation using a /sup 3/H-cytochalasin B binding assay. The increase in the rate of insulin-sensitive glucose transport directly parallels an increase in the number of transporters which reside in an insulin-responsive intracellular compartment. This observation was confirmed by identifying the transporters by immunoblotting using an antibody generated against the human erythrocyte transporter. The molecular weight of this transporter increases over differentiation from a single band of 40kDa to a heterogeneous triplet of 40, 44 and 48kDa. These data suggest that the transporter undergoes differential processing and that the functional, insulin-responsive transporter may be different from the insulin-insensitive (basal) transporter.

  2. Design of an active-passive device for human ankle movement during functional magnetic resonance imaging analysis.

    PubMed

    Belforte, Guido; Eula, Gabriella

    2012-01-01

    Functional magnetic resonance imaging analysis has made major strides in recent years, both because of the development of new scanners and owing to magnetic resonance compatible systems that make it possible to stimulate parts of the human body during analysis. The significant gains in our knowledge of the brain that can thus be achieved justify efforts to construct machines with control circuits suitable for this purpose. This paper presents a magnetic resonance compatible mechatronic device with electropneumatic control that can be used to move one or both feet during functional magnetic resonance imaging analysis of the cerebral motor zones. The system is innovative and original. The results obtained at the end of the investigation were good, and demonstrated that the design is feasible. PMID:22888581

  3. ATF3 inhibits adipocyte differentiation of 3T3-L1 cells

    SciTech Connect

    Jang, Min Kyung; Kim, Cho Hee; Seong, Je Kyung; Jung, Myeong Ho

    2012-04-27

    Highlights: Black-Right-Pointing-Pointer Overexpression of ATF3 inhibits adipocyte differentiation in 3T3-L1 cells. Black-Right-Pointing-Pointer Overexpression of ATF3 represses C/EBP{alpha} expression. Black-Right-Pointing-Pointer ATF3 directly binds to mouse C/EBP{alpha} promoter spanning from -1928 to -1907. Black-Right-Pointing-Pointer ATF3 may play a role in hypoxia-mediated inhibition of adipocyte differentiation. -- Abstract: ATF3 is a stress-adaptive gene that regulates proliferation or apoptosis under stress conditions. However, the role of ATF3 is unknown in adipocyte cells. Therefore, in this study, we investigated the functional role of ATF3 in adipocytes. Both lentivirus-mediated overexpression of ATF3 and stably-overexpressed ATF3 inhibited adipocyte differentiation in 3T3-L1 cells, as revealed by decreased lipid staining with oil red staining and reduction in adipogenic genes. Thapsigargin treatment and overexpression of ATF3 decreased C/EBP{alpha} transcript and repressed the activity of the 3.6-kb mouse C/EBP{alpha} promoter, demonstrating that ATF3 downregulates C/EBP{alpha} expression. Transfection studies using mutant constructs containing 5 Prime -deletions in the C/EBP{alpha} promoter revealed that a putative ATF/CRE element, GGATGTCA, is located between -1921 and -1914. Electrophoretic mobility shift assay and chromatin immunoprecipitation assay demonstrated that ATF3 directly binds to mouse C/EBP{alpha} promoter spanning from -1928 to -1907. Both chemical hypoxia-mimetics or physical hypoxia led to reduce the C/EBP{alpha} mRNA and repress the promoter activity of the C/EBP{alpha} gene, whereas increase ATF3 mRNA, suggesting that ATF3 may contribute to the inhibition of adipocyte differentiation in hypoxia through downregulation of C/EBP{alpha} expression. Collectively, these results demonstrate that ATF3 represses the C/EBP{alpha} gene, resulting in inhibition of adipocyte differentiation, and thus plays a role in hypoxia-mediated inhibition

  4. Magnetic properties and paleointensities as function of depth in a Hawai'ian lava flow

    NASA Astrophysics Data System (ADS)

    Dekkers, M. J.; de Groot, L. V.; ter Maat, G. W.

    2013-12-01

    The outcome of paleointensity experiments largely depends on the rock-magnetic properties of the samples. To assess the relation between volcanic emplacement processes and rock-magnetic properties we sampled a vertical transect in a ~6 m thick inflated lava flow at Hawai'i, with an age of 588 (558 - 640) AD (Rubin et al., 1987, recalibrated with INTCAL.09). This profile was sampled at sixteen levels in the flow; at six of these levels up to twelve samples were taken horizontally to have sufficient sample material for paleointensity experiments. Samples from all levels were rock magnetically characterized by determining hysteresis loops and FORC (first-order-reversal-curve) diagrams, and the low-field susceptibility, all at room temperature. To test for thermochemical alteration the temperature dependence of the low-field susceptibility and magnetization was determined. Overall, rock magnetic properties appear to vary as function of distance from the top; the observations can be correlated to the typical cooling rate profile for such a flow. The solidified crust under which the flow continued to flow during emplacement is ~1.8 m thick. Its rock-magnetic properties - notably the low-field susceptibility and the coercivity ratio - are more variable than those of the inflated part underneath. FORC diagrams indicate a fair portion of very small superparamagnetic particles in the top and to a lesser extent the bottom parts of the flow. In line with their faster cooling the dominant titanomagnetite composition is ~TM60 with associated low Curie and unblocking temperatures. The titanomagnetite in the slower cooled central part of the flow is unmixed into the magnetite (~TM0) and ülvospinel end-members; the remanence has therefore high Curie and unblocking temperatures. FORC diagrams and hysteresis parameters indicate larger pseudo-single-domain particles. We performed both IZZI-Thellier and calibrated pseudo-Thellier (AGU Fall 2012 contribution GP43A-1122, submitted

  5. Surface Functionalization of Magnetic Iron Oxide Nanoparticles for MRI Applications – Effect of Anchoring Group and Ligand Exchange Protocol

    PubMed Central

    Smolensky, Eric D.; Park, Hee-Yun E.; Berquó, Thelma S.; Pierre, Valérie C.

    2011-01-01

    Hydrophobic magnetite nanoparticles synthesized from thermal decomposition of iron salts must be rendered hydrophilic for their application as MRI contrast agents. This process requires refunctionalizing the surface of the nanoparticles with a hydrophilic organic coating such as polyethylene glycol. Two parameters were found to influence the magnetic behavior and relaxivity of the resulting hydrophilic iron oxide nanoparticles: the functionality of the anchoring group and the protocol followed for the functionalization. Nanoparticles coated with PEGs via a catecholate-type anchoring moiety maintain the saturation magnetization and relaxivity of the hydrophobic magnetite precursor. Other anchoring functionalities, such as phosphonate, carboxylate, and dopamine decrease the magnetization and relaxivity of the contrast agent. The protocol for functionalizing the nanoparticles also influences the magnetic behavior of the material. Nanoparticles refunctionalized according to a direct biphasic protocol exhibit higher relaxivity than those refunctionalized according to a two-step procedure which first involves stripping the nanoparticles. This research presents the first systematic study of both the binding moiety and the functionalization protocol on the relaxivity and magnetization of water-soluble coated iron oxide nanoparticles used as MRI contrast agents. PMID:21861279

  6. Regulatory T Cells in Melanoma