scholarly journals Using Electromagnetic Properties to Identify and Design Superconducting Materials

2021 ◽  
Author(s):  
Fred Lacy

Superconductors have a wide array of applications, such as medical imaging, supercomputing, and electric power transmission, but superconducting materials only operate at very cold temperatures. Thus, the quest to engineer room temperature superconductors is currently a hot topic of research. To accomplish this mission, it is important to have a complete understanding of the material properties that are being used to create these superconductors. Understanding the atomic and electromagnetic properties of the prospective materials will provide tremendous insight into the best choice for the materials. Therefore, a theoretical model that incorporates electromagnetic field theory and quantum mechanics principles is utilized to explain the electrical and magnetic characteristics of superconductors. This model can be used to describe the electrical resistance response and why it vanishes at the material’s critical temperature. The model can also explain the behavior of magnetic fields and why some superconducting materials completely exclude magnetic fields while other superconductors partially exclude these fields. Thus, this theoretical analysis produces a model that describes the behavior of both type I and type II superconductors. Since there are subtle differences between superconductors and perfect conductors, this model also accounts for this distinction and explains why superconductors behave differently than perfect conductors. Therefore, this theory addresses the major properties associated with superconducting materials and thus will aid researchers in the pursuit of designing room temperature superconductors.


1984 ◽  
Vol 47 (1) ◽  
pp. 49-52 ◽  
Author(s):  
THOMAS L. DEARDORFF ◽  
RICHARD B. RAYBOURNE ◽  
ROBERT S. DESOWITZ

This study reports effects of storage at cold temperatures on behavior and survival of third-stage larvae of Terranova sp. (type HA) and Anisakis simplex (type I) in marine fishes. Snappers, caught near the Hawaiian Islands, were examined to determine whether type HA and type I larvae could migrate from the viscera of ungutted fishes into edible musculature when maintained at 12, 8, and 0°C. Our data are suggestive that both type HA and type I larvae possess the ability to migrate. Temperatures of 12, 8, and 0°C had no noticable adverse affect on viability of both larval types within fish tissues; however, both larval types were extremely sensitive to temperatures below freezing. Death of both larval types encysted within Hawaiian snappers occurred by day 4 at −5°C and within 24 h at −10, −15, and −20°C. Other type I larvae, collected from fishes (Sebastes spp.) imported to Hawaii from the western Pacific, survived for slightly longer periods at −5, −10, −15, and −20°C when compared with type I larvae from Hawaiian fishes. Subjecting Hawaiian snappers to at least −20°C for 1 d and imported rockfishes to at least −20°C for 5 d is recommended to inactivate the living anisakines before ingesting any raw fish products.



2012 ◽  
Vol 27 (3) ◽  
pp. 032001 ◽  
Author(s):  
Kristijonas Vizbaras ◽  
Markus-Christian Amann


2012 ◽  
Vol 24 (14) ◽  
pp. 2664-2672 ◽  
Author(s):  
Sebastián A. Larrégola ◽  
José C. Pedregosa ◽  
Miguel Algueró ◽  
Ricardo Jiménez ◽  
Mar García-Hernandez ◽  
...  


2019 ◽  
Vol 19 (2) ◽  
pp. 89-94
Author(s):  
Muhammad Ilham Maulana

[ID] Ketergantungan manusia terhadap teknologi memasuki Revolusi Industri 4.0 sangat tinggi. Contoh penerapan inovasi di bidang teknologi informasi salah satunya adalah superkomputer dari material superkonduktor. Material superkonduktor identik dengan material non ferromagnetik karena sifatnya diamagnetis sempurna. Namun, sejak ditemukannya material superkonduktor berbasis logam ferromagnetik, penelitian terus dikembangkan, salah satunya material FeSe. Beberapa parameter yang perlu diperhatikan pada pembuatan material FeSe untuk memperoleh sifat superkonduktor terbaiknya diantaranya komposisi stoikiometri, penambahan doping, dan proses pembuatan material FeSe seperti proses pemaduan dan sintering. Dalam penelitian ini, pengaruh variasi doping Mg akan dianalisis terhadap sifat superkonduktor, morfologi, dan fasa yang terbentuk pada material superkonduktor FeSe. Material FeSe dibuat dengan metode reaksi padatan dalam tabung tertutup (Powder in Sealed Tube) secara insitu. Temperatur sintering yang digunakan 845⁰C yang ditahan selama 6 jam, dengan kenaikan temperatur 7⁰C/menit dari temperatur kamar, dan laju pendinginan normalizing. Kandidat material superkonduktor terbaik terdapat pada sampel Mg0.01Fe0.99Se. Didapatkan Temperatur kritis (Tc)onset = 15.42 K dan Tczero = 5.4 K. Morfologi sampel menunjukkan kristalisasi besar. Lalu, persentase fraksi volume fasa superkonduktornya juga merupakan yang terbesar yaitu 81.99%. [EN] Human dependence on technology into the Industrial Revolution 4.0 is very high. Example, the application of innovations in information technology is supercomputer from superconducting materials. Superconducting materials are identical from non-ferromagnetic materials because tend perfectly diamagnetic. However, since ferromagnetic-metal-based superconducting material discovered, research continues to be developed, like FeSe material. Some parameters that need to be considered in making FeSe material to obtain the best superconductor properties include stoichiometric composition, doping addition, and process of making FeSe materials like synthesis and sintering treatment. In this study, the effect of Mg-doped variations will be analyzed towards properties of superconductors, morphology, and phases formed in FeSe superconducting materials. MgxFe1-xSe made by solid-state reaction method in sealed tube (Powder in Sealed Tube) “insituely”. The sintering temperature used 845⁰C which held for 6 hours, with 7⁰C/minute temperature rise from room-temperature and normalizing cooling rate used. The best candidate superconducting material came from Mg0.01Fe0.99Se, obtained critical temperature (Tc)onset = 15.42 K, and Tczero = 5.4 K. Sample morphology shows a large crystallization. Then, the percentage fraction of the superconducting phase was also the largest, which is 81.99%.



Author(s):  
N. Y. Jagath B. Nikapitiya ◽  
Hyejin Moon

This paper reports an experimental study of thermal conductivity of room temperature ionic liquids (RTILs) based magnetic nanofluids. Various magnetic nanoparticles of metal oxides with high thermal conductivity, such as CuO, Al2O3, Fe3O4 and Carbon Nano Tubes (CNTs), were used to prepare magnetic nanofluids, while RTIL, trihexyl (tetradecyl) posphonium dicyanamide was used as the base fluid. Two major parameters that affect to the thermal conductivity enhancement of fluids were investigated. The effect of particle concentration and external magnetic fields were tested. It was observed that the magnetic nanofluids thermal conductivities increase with increment of particle concentration and external magnetic field parallel to the temperature gradient. Besides, it was observed that under higher magnetic fields, thermal conductivity enhancement tends to approach a saturation state. Surfactant was used to disperse magnetic nanoparticles within the RTILs. The transient hot wire method was used for this investigation.



2018 ◽  
Vol 30 (30) ◽  
pp. 305803 ◽  
Author(s):  
Ralf Wunderlich ◽  
Jonas Kohlrautz ◽  
Bernd Abel ◽  
Jürgen Haase ◽  
Jan Meijer


2019 ◽  
Vol 392 ◽  
pp. 123-137 ◽  
Author(s):  
Mohamed A. Medebber ◽  
Abderrahmane Aissa ◽  
Mohamed El Amine Slimani ◽  
Noureddine Retiel

The two dimensional study of natural convection in vertical cylindrical annular enclosure filled with Cu-water nanofluid under magnetic fields is numerically analyzed. The vertical walls are maintained at different uniform hot and cold temperatures, THand TC, respectively. The top and bottom walls of the enclosure are thermally insulated. The governing equations are solved numerically by using a finite volume method. The coupling between the continuity and momentum equations is effected using the SIMPLER algorithm. Numerical analysis has been carried out for a wide range of Rayleigh number (103≤Ra≤106), Hartmann number (1 ≤Ha≤100) and nanoparticles volume fraction (0 ≤φ≤0.08). The influence of theses physical parameters on the streamlines, isotherms and average Nusselt has been numerically investigated.



2019 ◽  
Vol 622 ◽  
pp. A72 ◽  
Author(s):  
F. Villebrun ◽  
E. Alecian ◽  
G. Hussain ◽  
J. Bouvier ◽  
C. P. Folsom ◽  
...  

Context. The origin of the fossil magnetic fields detected in 5 to 10% of intermediate-mass main sequence stars is still highly debated.Aims. We want to bring observational constraints to a large population of intermediate-mass pre-main sequence (PMS) stars in order to test the theory that convective-dynamo fields generated during the PMS phases of stellar evolution can occasionally relax into fossil fields on the main sequence.Methods. Using distance estimations, photometric measurements, and spectropolarimetric data from HARPSpol and ESPaDOnS of 38 intermediate-mass PMS stars, we determined fundamental stellar parameters (Teff,Landvsini) and measured surface magnetic field characteristics (including detection limits for non-detections, and longitudinal fields and basic topologies for positive detections). Using PMS evolutionary models, we determined the mass, radius, and internal structure of these stars. We compared different PMS models to check that our determinations were not model-dependant. We then compared the magnetic characteristics of our sample accounting for their stellar parameters and internal structures.Results. We detect magnetic fields in about half of our sample. About 90% of the magnetic stars have outer convective envelopes larger than ∼25% of the stellar radii, and heavier than ∼2% of the stellar mass. Going to higher mass, we find that the magnetic incidence in intermediate-mass stars drops very quickly, within a timescale on the order of few times 0.1 Myr. Finally, we propose that intermediate-mass T Tauri stars with large convective envelopes, close to the fully convective limit, have complex fields and that their dipole component strengths may decrease as the sizes of their convective envelopes decrease, similar to lower-mass T Tauri stars.



1984 ◽  
Vol 39 (3) ◽  
pp. 341-351 ◽  
Author(s):  
Joseph Grobe ◽  
Gerald Henkel ◽  
Bernt Krebs ◽  
Nikolaos Voulgarakis

Heterocyclic cage compounds of type I (compounds 8-10) have been prepared by condensation reactions of 1,2,2-trifunctional disilanes Me(R)XSiSiMeX2 (R = Me, Ph, OEt; X = NMe2, OEt) with triethanolamine using the “Dilution Principle”. The starting compounds are obtained by Si-Me cleavage of Si2Me6 with acetylchloride/AlCl3 followed by either aminolysis with HNMe2 or alcoholysis with EtOH. 1H NMR spectra indicate N→Si(1) intraction with the more acidic Si atom in 8 and 9. This result is proved by the X-ray structure analysis of 8 (monoclinic, P21/c; a = 7,088(2), b = 15,070(4), c = 12,701(4) Å, β = 104,96(2) at -130 °C, Z = 4); the Si(1)···N distance is found to be 2,768 Å , connected with a significant angular distortion of the tetrahedral coordination around Si(1) towards a trigonal bipyramid. In compound 10, too, N→Si(1) coordination is observed at room temperature in spite of almost equal acidity for both Si atoms. This can be explained by the preference of 5- over 6-membered chelating ring systems. At higher temperatures the 1H NMR spectra show a fluctuation of the N-donor between the two Si centres.



2020 ◽  
Vol 21 (3) ◽  
pp. 750 ◽  
Author(s):  
Mariangela Scavone ◽  
Silvia Bozzi ◽  
Tatiana Mencarini ◽  
Gianmarco Podda ◽  
Marco Cattaneo ◽  
...  

Microfluidic flow chambers (MFCs) allow the study of platelet adhesion and thrombus formation under flow, which may be influenced by several variables. We developed a new MFC, with which we tested the effects of different variables on the results of platelet deposition and thrombus formation on a collagen-coated surface. Methods: Whole blood was perfused in the MFC over collagen Type I for 4 min at different wall shear rates (WSR) and different concentrations of collagen-coating solutions, keeping blood samples at room temperature or 37 °C before starting the experiments. In addition, we tested the effects of the antiplatelet agent acetylsalicylic acid (ASA) (antagonist of cyclooxygenase-1, 100 µM) and cangrelor (antagonist of P2Y12, 1 µM). Results: Platelet deposition on collagen (I) was not affected by the storage temperature of the blood before perfusion (room temperature vs. 37 °C); (II) was dependent on a shear rate in the range between 300/s and 1700/s; and (III) was influenced by the collagen concentration used to coat the microchannels up to a value of 10 µg/mL. ASA and cangrelor did not cause statistically significant inhibition of platelet accumulation, except for ASA at low collagen concentrations. Conclusions: Platelet deposition on collagen-coated surfaces is a shear-dependent process, not influenced by the collagen concentration beyond a value of 10 µg/mL. However, the inhibitory effect of antiplatelet drugs is better observed using low concentrations of collagen.



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