Magnetic properties of a nanocrystalline material for current derivative sensors of magnets protection systems

Nanocrystalline materials are becoming ever more broadly used in transformer-based transducers due to their low losses, high relative permeability and high saturation flux density. In this paper, the magnetic characterization of one of these materials is presented by highlighting its influence on the performance of a current derivative sensor. This sensor was recently prototyped at CERN in the framework of the consolidation activity on the quench protection of superconducting magnets for the high-luminosity upgrade of the Large Hadron Collider. The performance is analyzed in terms of linearity and dynamic response

A Static-Sample Magnetometer for Characterizing Weak Magnetic Materials

In this paper, a static-sample magnetometer is presented to measure the relative permeability of weakly magnetic materials. The method consists of scanning the magnetic field inside a dipole magnet by using an NMR teslameter to measure the perturbation of a test specimen on the externally applied field. Then, an inverse problem is used to compute the specimen's relative permeability. As a case study, the measurement of three different materials with different shapes and dimensions is carried out. The method was validated by measuring the same material by a vibrating sample magnetometry as proposed by the standard ASTM A342/A342M-14. The Monte Carlo evaluated expanded measurement uncertainty of the relative permeability is about 10 −4 for all the cases, with a level of confidence of 95 %

A Superconducting Permeameter for Characterizing Soft Magnetic Materials at High Fields

Asuperconductingpermeameterisproposedtocharacterizethemagneticpropertiesofhigh-energysuperconducting magnet yokes at their operating temperatureand saturation level. The main problem of superconductingcoils, an undesired quench, was faced by specific protectionsimulations, which has led to a self-protected system. Thesuperconducting permeameter was used to perform the magneticcharacterization of ARMCO Pure Iron, the material for the newHigh-Luminosity Large Hadron Collider (HL-LHC) supercon-ducting magnet yokes, which was performed at the cryogenictemperature of 4.2 K and a saturation level of nearly 3 T.Two case studies based on the new HL-LHC superconductingquadrupole and dipole magnets highlight the impact of themagnetic properties of the yoke on the performance of thesuperconducting magnets, showing that the common assumptionthat heavily saturated steels with similar chemical compositionbehave precisely the same way has been proven wrong

Synergistic association of valproate and resveratrol reduces brain injury in ischemic stroke

Histone deacetylation, together with altered acetylation of NF-κB/RelA, encompassing the K310 residue acetylation, occur during brain ischemia. By restoring the normal acetylation condition, we previously reported that sub-threshold doses of resveratrol and entinostat (MS-275), respectively, an activator of the AMP-activated kinase (AMPK)-sirtuin 1 pathway and an inhibitor of class I histone deacetylases (HDACs), synergistically elicited neuroprotection in a mouse model of ischemic stroke. To improve the translational power of this approach, we investigated the efficacy of MS-275 replacement with valproate, the antiepileptic drug also reported to be a class I HDAC blocker. In cortical neurons previously exposed to oxygen glucose deprivation (OGD), valproate elicited neuroprotection at 100 nmol/mL concentration when used alone and at 1 nmol/mL concentration when associated with resveratrol (3 nmol/mL). Resveratrol and valproate restored the acetylation of histone H3 (K9/18), and they reduced the RelA(K310) acetylation and the Bim level in neurons exposed to OGD. Chromatin immunoprecipitation analysis showed that the synergistic drug association impaired the RelA binding to the Bim promoter, as well as the promoter-specific H3 (K9/18) acetylation. In mice subjected to 60 min of middle cerebral artery occlusion (MCAO), the association of resveratrol 680 µg/kg and valproate 200 µg/kg significantly reduced the infarct volume as well as the neurological deficits. The present study suggests that valproate and resveratrol may represent a promising ready-to-use strategy to treat post-ischemic brain damage

Studio della variabilità al 5’ della regione genomica non tradotta (UTR) dell’RNA virale del virus delle ali deformi (DWV)

Un indagine volta ad individuare possibili varianti del virus, attraverso la caratterizzazione molecolare della regionenon tradotta (UTR) del 5' dell'RNA virale di diversi isolati del DWV associati a famiglie di api allevate in Campania

On the use of fluxmetric methods for characterizing feebly magnetic materials

The problems related to the use of a split-coil permeameter for measuring the magnetic properties of materials with low relative permeability are faced. In particular, a challenging problem arises from the series production of steel tapes: magnetic and paramagnetic materials, in fact, exhibit different magnetic properties according to the production process (i.e. annealing and cold work). Consequently, samples of this material differently treated have to be characterized in order to find the optimal cold work and annealing able to minimize raising of magnetism. In this paper, fluxmetric methods, widely employed for magnets testing, are extended to the characterization of feebly magnetic materials. A case study for the series production of steel tapes about co-wound 1.430 stainless steel tapes, the material used for the quench detection in ITER TF coils [1], is presented

Inverse Problem-Based Magnetic Characterization of Weekly Magnetic Alloys

Understanding the magnetic properties of materials used in accelerator components is becoming more and more important. For example, in the upcoming LHC upgrade at CERN, the increasing luminosity will boost the radiation dose received by the accelerator magnet's coil and consequently decrease its lifespan. Hence, a radiation shield with relative permeability less than 1.005 is required. The goal of this research is to design and validate a new method for characterizing weekly magnetic materials, suitable to be used in quality control of series production. The proposed method is based on inverse analysis approach coupled with a finite-element model. A material with unknown permeability is inserted in the air gap of a dipole magnet and the consequent perturbations of the dipole background flux density are measured. The magnetic permeability is then identified through gray-box inverse modelling, based on a finite-element approach. The results have been used to predict the magnetic impact of the radiation shield and develop further research on this subject