scholarly journals Broadband Ferromagnetic Resonance Measurements in Ni/ZnO and Niγ-Fe2O3Nanocomposites

2007 ◽  
Vol 2007 ◽  
pp. 1-16 ◽  
Author(s):  
Vincent Castel ◽  
Jamal Ben Youssef ◽  
Christian Brosseau
Keyword(s):  
Magnetic Field ◽  
Ferromagnetic Resonance ◽  
Resonance Field ◽  
Anisotropy Field ◽  
Clear Correlation ◽  
Line Broadening ◽  
Absorbed Power ◽  
Field Modulation ◽  
The One ◽  
Lock In

A comparative study at the ambient temperature of the ferromagnetic resonance (FMR) spectra of Ni/ZnO andNi/γ-Fe2O3nanocomposites (NCs) is reported. A microstrip transmission line technique was used to measure the FMR profiles and linewidths in the 8–24 GHz frequency range. The samples were placed at the center of a microstrip line where the derivative of the absorbed power was measured using a standard ac field modulation technique (10 Oe amplitude) and lock-in detection. The analysis of the FMR spectra can be interpreted as arising from aggregates of magnetic nanoparticles, each of which resonates in an effective magnetic field composed of the applied field, the average (magnetostatic) dipolar field, and the randomly oriented magnetic anisotropy field. It is found that frequency and applied magnetic field strongly influence the lineshape of the FMR spectra. Two observations are identified within the FMR spectra. On the one hand, the resonance field increased linearly with frequency as expected from uniform mode theory and yielded a Landégfactor in the range 1.48–2.05. On the other hand, there is no clear correlation between FMR linewidths and frequency. Inhomogeneity-based line-broadening mechanisms, due to the damping of surface/interface effects and interparticle interaction, affect the FMR effective linewidth.

scholarly journals Spin torque ferromagnetic resonance with magnetic field modulation

2013 ◽  
Vol 103 (17) ◽  
pp. 172406 ◽  
Author(s):  
A. M. Gonçalves ◽  
I. Barsukov ◽  
Y.-J. Chen ◽  
L. Yang ◽  
J. A. Katine ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Ferromagnetic Resonance ◽  
Spin Torque ◽  
Magnetic Field Modulation ◽  
Field Modulation

Ferromagnetic Resonance Biosensor for Homogeneous and Volumetric Detection of DNA

2017 ◽  
Author(s):  
Bo Tian ◽  
Peter Svedlindh ◽  
Mattias Strömberg ◽  
Erik Wetterskog
Keyword(s):  
Magnetic Nanoparticles ◽  
Ferromagnetic Resonance ◽  
Limit Of Detection ◽  
Point Of Care ◽  
Rolling Circle Amplification ◽  
Resonance Field ◽  
Isothermal Amplification ◽  
Detection Sensitivity ◽  
Serum Samples ◽  
Rolling Circle

In this work, we demonstrate for the first time, a ferromagnetic resonance (FMR) based homogeneous and volumetric biosensor for magnetic label detection. Two different isothermal amplification methods, <i>i.e.</i>, rolling circle amplification (RCA) and loop-mediated isothermal amplification (LAMP) are adopted and combined with a standard electron paramagnetic resonance (EPR) spectrometer for FMR biosensing. For RCA-based FMR biosensor, binding of RCA products of a synthetic Vibrio cholerae target DNA sequence gives rise to the formation of aggregates of magnetic nanoparticles. Immobilization of nanoparticles within the aggregates leads to a decrease of the net anisotropy of the system and a concomitant increase of the resonance field. A limit of detection of 1 pM is obtained with an average coefficient of variation of 0.16%, which is superior to the performance of other reported RCA-based magnetic biosensors. For LAMP-based sensing, a synthetic Zika virus target oligonucleotide is amplified and detected in 20% serum samples. Immobilization of magnetic nanoparticles is induced by their co-precipitation with Mg<sub>2</sub>P<sub>2</sub>O<sub>7</sub> (a by-product of LAMP) and provides a detection sensitivity of 100 aM. The fast measurement, high sensitivity and miniaturization potential of the proposed FMR biosensing technology makes it a promising candidate for designing future point-of-care devices.<br>

Correlation between electrical and rheological measurements on sewage sludge

2007 ◽  
Vol 2 (1) ◽  
Author(s):  
E. Dieudé-Fauvel ◽  
J.-C. Baudez ◽  
P. Coussot ◽  
H. Van Damme
Keyword(s):  
Sewage Sludge ◽  
Rheological Parameters ◽  
Clear Correlation ◽  
Electrical Measurements ◽  
Rheological Measurements ◽  
Sludge Characterization ◽  
Relaxation Experiments ◽  
Rheological Experiments ◽  
The One ◽  
Microstructure Of The Material

In order to improve sewage sludge characterization for both dewatering and agricultural spreading, we have studied their electrical and rheological properties. On the one hand, electrical measurements give a picture of the microstructure of the material (charges, particles mobility), whereas on the other hand, rheological experiments describe its macrostructure (consistency). The interactions of the matter are the link between them. Our results showed that sludge becomes more conductive when its dry content (for a defined composition) or the temperature increases, and also during aging. In parallel its apparent viscosity increases with the dry content but decreases with the temperature or during aging. In each case a clear correlation was found between electrical and rheological parameters. This relationship clearly depends on sludge composition, and also on parameters such as the temperature, the observation frequency, the velocity range in the case of relaxation experiments. Finally, those types of experiments can be correlated to improve the comprehension of sludge structure and consistency characterization.

The Dilemma between Aligned Expectations and Diversity in Innovation

2018 ◽  
Author(s):  
Timur Ergen
Keyword(s):  
New Technologies ◽  
Historical Case ◽  
History Of Capitalism ◽  
Synthetic Fuel ◽  
The Us ◽  
History Of ◽  
The One ◽  
Technology Policies ◽  
Lock In ◽  
Innovation Processes

This chapter brings together arguments from economics, sociology, and political economy to show that innovation processes are characterized by a dilemma between the advantages of aligned expectations—including greater coordination and investment—and those of diversity, including superior openness to new technological possibilities. To illustrate the argument, the chapter discusses a historical case involving one of the largest coordinated peace-time attempts to hasten technological innovation in the history of capitalism, namely the US energy technology policies of the 1970s and 1980s. Close examination of the commercialization of photovoltaics and synthetic fuel initiatives illustrates both sides of the dilemma between shared versus diverse expectations in innovation: coordination but possible premature lock-in on the one hand, and openness but possible stagnation on the other. The chapter shows that even the exploration and interpretation of new technologies may be as much a product of focused investment as of trial-and-error search.

scholarly journals Tacit Collusion with Consumer Preference Costs

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Guillem Roig
Keyword(s):  
Switching Costs ◽  
Consumer Preference ◽  
Hand Preference ◽  
Dominant Strategy ◽  
The Other ◽  
Tacit Collusion ◽  
Other Hand ◽  
The One ◽  
Opposing Effects ◽  
Lock In

Abstract When consumers have preference costs, two opposing effects need to be assessed to analyse the incentives of firms to set collusive prices. On the one hand, preference costs make a deviation from collusion less attractive, as the deviating firm must offer a large enough discount to cover the preference costs. On the other hand, preference costs lock in consumers and make punishment from rivals less effective. When preference costs are low, the latter of the two effects dominates and collusion is more challenging to sustain than in a situation with no preference costs. With high enough preference costs, collusion is a (weakly) dominant strategy. These results do not eventuate in a model with switching costs.

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