Search results for "High field"
showing 10 items of 16 documents
Characterizing microstructural tissue properties in multiple sclerosis with diffusion MRI at 7 T and 3 T: The impact of the experimental design
2019
The recent introduction of advanced magnetic resonance (MR) imaging techniques to characterize focal and global degeneration in multiple sclerosis (MS), like the Composite Hindered and Restricted Model of Diffusion, or CHARMED, diffusional kurtosis imaging (DKI) and Neurite Orientation Dispersion and Density Imaging (NODDI) made available new tools to image axonal pathology non-invasively in vivo. These methods already showed greater sensitivity and specificity compared to conventional diffusion tensor-based metrics (e.g., fractional anisotropy), overcoming some of its limitations. While previous studies uncovered global and focal axonal degeneration in MS patients compared to healthy contr…
Towards the development of a fossil bone geochemical standard: An inter-laboratory study
2007
Ten international laboratories participated in an inter-laboratory comparison of a fossil bone composite with the objective of producing a matrix and structure-matched reference material for studies of the bio-mineralization of ancient fossil bone. We report the major and trace element compositions of the fossil bone composite, using in-situ method as well as various wet chemical digestion techniques. For major element concentrations, the intra-laboratory analytical precision (%RSDr) ranges from 7 to 18%, with higher percentages for Ti and K. The %RSDr are smaller than the inter-laboratory analytical precision (%RSDR; 100% was found for the high field strength elements (Hf, Th, Zr, Nb). The…
Sesquiterpene Lactones fromCentaurea paui
1994
Abstract A new elemanolide and two new heliangolides as well as (2R,3R)-(+)-3-hydroxy-2-methyl-butyrolactone have been isolated from Centaurea paui. The structures were elucidated by high field NMR techniques and chemical transformation.
The Influence of All-Night Exposure to Pulsed Radiofrequency Electromagnetic Fields on Human Sleep. Der Einfluss kontinuierlicher nachtlicher Exposit…
2005
Question of the study The widespread use of mobile telephones has led to public discussion about the putative health hazards as well as scientific interest in the interactions of pulsed, high-frequency electromagnetic fields with physiological systems. This article presents a survey of three consecutive studies carried out by a research group at the University of Mainz.
Generation of energy selective excitations in quantum hall edge states
2011
We operate an on-demand source of single electrons in high perpendicular magnetic fields up to 30T, corresponding to a filling factor below 1/3. The device extracts and emits single charges at a tunable energy from and to a two-dimensional electron gas, brought into well defined integer and fractional quantum Hall (QH) states. It can therefore be used for sensitive electrical transport studies, e.g. of excitations and relaxation processes in QH edge states.
Preparation of Biomolecule Microstructures and Microarrays by Thiol-ene Photoimmobilization
2009
A mild, fast and flexible method for photoimmobilization of biomolecules based on the light-initiated thiol-ene reaction has been developed. After investigation and optimization of various surface materials, surface chemistries and reaction parameters, microstructures and microarrays of biotin, oligonucleotides, peptides, and MUC1 tandem repeat glycopeptides were prepared with this photoimmobilization method. Furthermore, MUC1 tandem repeat glycopeptide microarrays were successfully used to probe antibodies in mouse serum obtained from vaccinated mice. Dimensions of biomolecule microstructures were shown to be freely controllable through photolithographic techniques, and features down to 5 …
X-Ray Detected Magnetic Resonance: A Unique Probe of the Precession Dynamics of Orbital Magnetization Components
2011
X-ray Detected Magnetic Resonance (XDMR) is a novel spectroscopy in which X-ray Magnetic Circular Dichroism (XMCD) is used to probe the resonant precession of local magnetization components in a strong microwave pump field. We review the conceptual bases of XDMR and recast them in the general framework of the linear and nonlinear theories of ferromagnetic resonance (FMR). Emphasis is laid on the information content of XDMR spectra which offer a unique opportunity to disentangle the precession dynamics of spin and orbital magnetization components at given absorbing sites. For the sake of illustration, we focus on selected examples in which marked differences were found between FMR and XDMR s…
High Electrocaloric Effect in Ferroelectrics
2010
The existing situation in prospects of application of electrocaloric effect (ECE), related to finding ferroelectrics exhibiting high values of ECE, is discussed. Besides 1st order ferroelectric-paraelectric phase transitions, which were most promising till recent time with respect to high values of ECE, there are other approaches, related to ECE in high field range in relaxors and polymers. The restrictions of application of traditional indirect evaluation of ECE in ferroelectrics are discussed.
The influence of surface treatment on the anodizing of magnesium in alkaline solution
2011
Abstract The mechanism of magnesium anodizing after mechanical polishing or HF pickling was studied. X-ray Photoelectron Spectroscopy and Photocurrent Spectroscopy were employed to characterize both the initial films formed on Mg soon after surface treatments and the anodic films grown in strongly alkaline solutions. Electrochemical and capacitance measurements were performed in order to study the oxidation process and to check if the kinetic of growth fits the Mott–Cabrera high field model. From Tafel plots it was possible to estimate the activation distance, while the simulation of the barrier layer growth as a function of the potential at high scan rate allowed to estimate the other kine…
Chapter 23. Singlet Order in Heteronuclear Spin Systems
2020
The concept of heteronuclear Long-Lived spin States (LLSs) is introduced. In the simplest case of a pair of heteronuclei, such states are given by the singlet order of the spin pair, which can be efficiently sustained under Zero or Ultra-Low Field (ZULF) conditions. Here we describe two possible ways of detecting long-lived singlet order of heteronuclei: detection at ZULF conditions and NMR (Nuclear Magnetic Resonance) detection at high field utilising fast field-cycling. A theoretical description of the underlying spin dynamics is presented for both cases; the discussion is supported by experimental examples of LLSs in 13CH groups. The generality of these phenomena is discussed, as well as…