Pulsed-field magnetization of drilled bulk high-temperature superconductors: flux front propagation in the volume and on the surface

We present a method for characterizing the propagation of the magnetic flux in an artificially drilled bulk high-temperature superconductor (HTS) during a pulsed-field magnetization. As the magnetic pulse penetrates the cylindrical sample, the magnetic flux density is measured simultaneously in 16 holes by means of microcoils that are placed across the median plane, i.e. at an equal distance from the top and bottom surfaces, and close to the surface of the sample. We discuss the time evolution of the magnetic flux density in the holes during a pulse and measure the time taken by the external magnetic flux to reach each hole. Our data show that the flux front moves faster in the median plane than on the surface when penetrating the sample edge; it then proceeds faster along the surface than in the bulk as it penetrates the sample further. Once the pulse is over, the trapped flux density inside the central hole is found to be about twice as large in the median plane than on the surface. This ratio is confirmed by modelling

Bulk high-Tc superconductors with drilled holes: how to arrange the holes to maximize the trapped magnetic flux ?

Drilling holes in a bulk high-Tc superconductor enhances the oxygen annealing and the heat exchange with the cooling liquid. However, drilling holes also reduces the amount of magnetic flux that can be trapped in the sample. In this paper, we use the Bean model to study the magnetization and the current line distribution in drilled samples, as a function of the hole positions. A single hole perturbs the critical current flow over an extended region that is bounded by a discontinuity line, where the direction of the current density changes abruptly. We demonstrate that the trapped magnetic flux is maximized if the center of each hole is positioned on one of the discontinuity lines produced by the neighbouring holes. For a cylindrical sample, we construct a polar triangular hole pattern that exploits this principle; in such a lattice, the trapped field is ~20% higher than in a squared lattice, for which the holes do not lie on discontinuity lines. This result indicates that one can simultaneously enhance the oxygen annealing, the heat transfer, and maximize the trapped field

The result of stratigic filtering to all levels of management

Abstract: Strategies commonly over promise and under deliver, resulting in the development of discrepancies between the formulation and execution stage of a strategy. The research subsequently identified that far too often insufficient attention is paid to the value of effective communication and the role it plays in the filtering and execution of strategy..

Zidovudine-poly(l-lactic acid) solid dispersions with improved intestinal permeability prepared by supercritical antisolvent process

A supercritical antisolvent (SAS) process for obtaining zidovudine-poly(l-lactic acid) (PLLA) solid dispersions (SDs) was used to attain a better intestinal permeation of this drug. A 32 factorial design was used, having as independent variables the ratio 3-azido-23-dideoxythymidine (AZT)PLLA and temperature/pressure conditions, as dependent variables the process yield and particle macroscopic morphology. AZTPLLA production batches were carried out by the SAS process, and the resulting products evaluated via scanning electron microscope, X-ray diffraction, differential scanning calorimetry, and Fourier transform infrared analyses. From the nine possible combinations of tests performed experimentally, only one combination did not produced a solid. The L3 batch of SD, produced with 1:2 (AZTPLLA) ratio, resulted in a 91.54% yield, with 40% AZT content. Intestinal permeability studies using the AZTPLLA from L3 batch led to an AZT permeability of approximately 9.87%, which was higher than that of pure AZT (3.84%). AZT remained in crystalline form, whereas PLLA remained in semicrystalline form. AZT release is controlled by a diffusion mechanism. It has been demonstrated that it is possible to use PLLA carrier and SAS process to obtain SD, in a single step.Cristalia (Itapira, Brazil) for the kind supply of the reference substance used throughout the research work. Financial support from Fundação de Amparo á Pesquisa do Estado de São Paulo (2013-19300-4; 2012/01333-0; 2011/21219-5), Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (PROSUP/CAPES) and Finep Inovação e Pesquisa (Finep, Brazil; 01.13.0286.00)

Antiferromagnetic ordering in a 90 K copper oxide superconductor

Using elastic neutron scattering, we evidence a commensurate antiferromagnetic Cu(2) order (AF) in the superconducting (SC) high-$\rm T_c$ cuprate $\rm YBa_2(Cu_{1-y}Co_y)_3O_{7+\delta}$ (y=0.013, $\rm T_c$=93 K). As in the Co-free system, the spin excitation spectrum is dominated by a magnetic resonance peak at 41 meV but with a reduced spectral weight. The substitution of Co thus leads to a state where AF and SC cohabit showing that the CuO$_2$ plane is a highly antiferromagnetically polarizable medium even for a sample where T$_c$ remains optimum.Comment: 3 figure

Antibacterial activity of chitosan/collagen membranes containing red propolis extract

In this study we developed a mucoadhesive polymeric membrane wound dressing incorporating red propolis extract (HERP). Membranes were made using a casting method employing collagen, chitosan, polyethylene glycol (15, 20, and 30v%), and hydroethanolic extract of EtOH-H2O 70v% 30v% (v/v) of HERP (0.5, 1.0, and 1.5%). Membranes were extensively characterized to assess the thickness, pH, morphology using Scanning Electron Microscopy (SEM), Differential Scanning Calorimetry (DSC), mechanical properties, swelling, in vitro mucoadhesion, cytotoxicity, and minimum inhibitory concentration (MIC). Assessment of the thickness and mechanical properties of the membranes containing HERP revealed that the most significant thickness obtained was 40.7 m; thermal analysis suggests suggesting the hydrogen bonds between hydroxyl groups of isoflavones and the free amine present in the region of chitosan. Cell viability decreased as the amount of HERP increased. Finally, the MICs were 7.8 and 1.9 g.mL1 for Staphylococcus aureus ATCC 25923 and Pseudomonas aeruginosa ATCC 27853, respectively. These results were suggesting that the 0.5 % HERP membrane has the potential for future studies for wound application.The authors wish to acknowledge Coordenação Aperfeiçoamento de Pessoal de Nivel Superior (CAPES), Fundação de Amparo à Pesquisa do Estado de Sergipe (FAPITEC), Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq, #443238/2014-6, #470388/2014-5).info:eu-repo/semantics/publishedVersio

HTS Dipole Insert Developments

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Double membrane based on lidocaine-coated polymyxin-alginate nanoparticles for wound healing: in vitro characterization and in vivo tissue repair

The aim of this study was to develop and characterize a double layer biomembrane for dual drug delivery to be used for the treatment of wounds. The membrane was composed of chitosan, hydroxypropyl methylcellulose and lidocaine chloride (anesthetic drug) in the first layer, and of sodium alginate-polymyxin B sulphate (antibiotic) nanoparticles as the second layer. A product with excellent thickness (0.01-0.02 mm), adequate mechanical properties with respect to elasticity, stiffness, tension, and compatible pH for lesion application has been successfully obtained. The incorporation of the drugs was confirmed analysing the membrane cross-sections by scanning electron microscopy. A strong interaction between the drugs and the functional groups of respective polymers was confirmed by Fourier-Transform Infrared Spectroscopy, thermal analysis and X-ray diffraction. Microbiological assays showed a high antimicrobial activity when polymyxin B was present to act against the Staphylococcus aureus and Pseudomonas aeruginosa strains. Low cytotoxicity observed in a cell viability colorimetric assay and SEM analysis suggest biocompatibility between the developed biomembrane and the cell culture. The in vivo assay allowed visualizing the healing potential by calculating the wound retraction index and by histological analysis. Our results confirm the effectiveness of the developed innovative biomaterial for tissue repair and regeneration in an animal model.The authors acknowledge the Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES/Brazil), Fundação de Amparo a Pesquisa do Estado de Sergipe (FAPITEC, MS/CNPq/FAPITEC/SE/SES N◦06/2018) e do Conselho Nacional de Pesquisas (CNPq, Apoio a Projetos de Pesquisa/MCTI/CNPQ/Universal 14/2014) for supporting funds. EBS acknowledges the Portuguese Science and Technology Foundation (FCT) for the funded projects M-ERA-NET/0004/2015 (PAIRED) and UIDB/04469/2020 (strategic fund) financed from national funds, and co-financed Education (FCT/MEC) from national funds and FEDER, under the Partnership Agreement PT2020.info:eu-repo/semantics/publishedVersio

Arnica montana : évaluation des ressources génétiques françaises en vue du développement de la culture en plaine et en montagne

Ce volume regroupe les textes issus du programme Casdar "Innovation et Partenariat" et "Recherche finalisée et innovation" de 2013. Le colloque de restitution s’est déroulé le 6 février 2019 sous l’égide du GIS Relance AgronomiqueArnica montana is a major medicinal specie, which is now mainly produced from wild harvesting,especially in mainland France. As the wild resource is decreasing, and in order to maintain or even Gourlin L. et al. 68 Innovations Agronomiques 71 (2019), 67-80 develop the French production, cultivation is a good option, that is still very limited, because of its difficulty. Finding the right plant material could help to enhance cultivation programs. This project aimed at growing 24 wild populations, which were collected in mainland France, and to compare them with 2 commercial varieties, ‘Arbo’ and ‘Arnimed’. This was set on 4 experimentation spots, chosen for their potential match for Arnica cultivation. The experiment lasted 3 years, and morphological andagronomical subjects were studied on the populations. Sesquiterpene lactones and flavonoidsanalyzed, and a new methodology of evaluation was developed. The results showed extreme variabilityof phenotypic and chemical expression of the different populations. An important death rate has beennoticed on wild populations, but the causes are still unknown. On the set of variables chosen,commercial varieties ‘Arbo’ and ‘Arnimed’ were particularly competitive, and two wild populations standout with promising results. One seems appropriate for starting selection works on a variety that would besuitable for loaw altitude, and the other one could be a local (French) alternative to the cultivation ofselected varieties (‘Arbo’ and ‘Arnimed’ are from Swiss and German selection work).L’arnica des montagnes est une espèce médicinale importante dont la production est principalementissue de la cueillette à l’état sauvage, notamment sur le territoire métropolitain. La ressource étant enrégression, le maintien, voire le développement de la production française passe donc par la mise enculture, actuellement anecdotique car difficile. Certains freins pourraient être levés par la mise enévidence de matériel végétal adapté à la production. L’objectif de ce projet était de mettre en culture 24populations d’origines sauvages (prospectées en France métropolitaine) et de les comparer à deuxvariétés commerciales témoins ‘Arbo’ et ‘Arnimed’, sur 4 sites d’expérimentation aux contextespédoclimatiques variés mais a priori adaptés à la culture de l’espèce. Durant les 3 années d’essai, unsuivi morphologique et agronomique des populations a été réalisé. Des analyses des sesquiterpèneslactones et flavonoïdes ont été effectuées, et une nouvelle méthodologie de dosage de ces composés aété développée. Les résultats mettent en exergue la forte variabilité de l’expression phénotypique etchimique des différentes souches testées. Une forte mortalité globale a pu être constatée surl’ensemble des populations sauvages étudiées sans que les causes aient pu en être identifiées. Surl’ensemble des variables suivies, les variétés commerciales ‘Arbo’ et ‘Arnimed’ sont particulièrementperformantes, et deux populations sauvages se démarquent par leurs résultats intéressants : l’uneparait pertinente pour démarrer des travaux de sélection d’une variété adaptée à la basse altitude,tandis que l’autre, originaire du Massif central, pourrait se proposer comme une alternative d’originelocale (française) à la culture de variétés commerciales sélectionnées (suisse et allemande)