Origin and tailoring of the antiferromagnetic domain structure in α\alpha-Fe2_2O3_3 thin films unraveled by statistical analysis of dichroic spectro-microscopy (X-PEEM) images

The magnetic microstructure and domain wall distribution of antiferromagnetic $\alpha$-Fe$_2$O$_3$ epitaxial layers is determined by statistical image analyses. Using dichroic spectro-microscopy images, we demonstrate that the domain structure is statistically invariant with thickness and that the antiferromagnetic domain structure of the thin films is inherited from the ferrimagnetic precursor layer one, even after complete transformation into antiferromagnetic $\alpha$-Fe$_2$O$_3$. We show that modifying the magnetic domain structure of the precursor layer is a genuine way to tune the magnetic domain structure and domain walls of the antiferromagnetic layers

X-ray photoelectron emission microscopy in combination with x-ray magnetic circular dichroism investigation of size effects on field-induced N\'eel-cap reversal

X-ray photoelectron emission microscopy in combination with x-ray magnetic circular dichroism is used to investigate the influence of an applied magnetic field on N\'eel caps (i.e., surface terminations of asymmetric Bloch walls). Self-assembled micron-sized Fe(110) dots displaying a moderate distribution of size and aspect ratios serve as model objects. Investigations of remanent states after application of an applied field along the direction of N\'eel-cap magnetization give clear evidence for the magnetization reversal of the N\'eel caps around 120 mT, with a $\pm$20 mT dispersion. No clear correlation could be found between the value of the reversal field and geometrical features of the dots

360 degree domain wall generation in the soft layer of magnetic tunnel junctions

High spatial resolution X-ray photo-emission electron microscopy technique has been used to study the influence of the dipolar coupling taking place between the NiFe and the Co ferromagnetic electrodes of micron sized, elliptical shaped magnetic tunnel junctions. The chemical selectivity of this technique allows to observe independently the magnetic domain structure in each ferromagnetic electrode. The combination of this powerful imaging technique with micromagnetic simulations allows to evidence that a 360 degree domain wall can be stabilized in the NiFe soft layer. In this letter, we discuss the origin and the formation conditions of those 360 degree domain walls evidenced experimentally and numerically

Isolement des bactéries lactiques à partir des produits laitiers traditionnels Marocains et formulation d’un lait fermenté proche du Kéfir

Les bactéries lactiques par leur biodiversité sont largement utilisées dans l’industrie agroalimentaire. L’objectif de cette étude est donc l’isolement des bactéries lactiques à partir de lben et jben marocains, l’étude de la vitesse d’acidification des isolats en culture pure et en culture mixte afin de trouver la meilleure combinaison à caractère acidifiant très rapide et très élevé et son utilisation pour formuler une boisson lactée fermentée proche du Kéfir. Les résultats montrent que les isolats obtenus appartiennent aux genres Lactobacillus, Lactococcus et Leuconostoc, que les Lactobacillus et les Lactococcus isolés en culture pure provoquent tous une diminution du pH du lait de 6,5 à 4,2 au bout de 24 heures de fermentation et que la souche Lb4 du genre Lactobacillus possède une forte propriété acidifiante. Cette souche a été utilisée en combinaison avec les Leuconostoc et les Lactococcus (CM1, CM2, CM3) et a donné une vitesse d’acidification plus rapide et un pH plus bas. Une boisson lactée fermentée proche du Kéfir qui est une boisson très reconnue par ses effets sanitaires et thérapeutiques est alors produite grâce à cette dernière combinaison et à l’ajout des levures (saccharomycess cerevisiae) et des bactéries acétiques (Acetobacter). Le résultat de ce travail a noté une bonne appréciation du nouveau produit par le jury de dégustation et une forte ressemblance au Kéfir qui est un produit d’origine Russe.Mots-clés: bactéries lactiques, Lactobacillus, Leuconostoc, Lactococcus, Lben, Jben, Kéfir. Isolation of lactic acid bacteria from traditional Moroccan dairy products and formulation of a loved fermented milk KefirLactic acid bacteria for their biodiversity and their therapeutic properties are widely used in the food industry. the interest of this study is the isolation of lactic acid bacteria from Lben and Jben Moroccan studying the acidification rate of isolates in pure culture and in mixed culture in order to find the best combination for fast acidifying character and very expensive and its use to make a fermented milk close Kefir . The results show that the isolates belong to the genera Lactobacillus, Lactococcus and Leuconostoc, Lactobacillus and the isolated pure culture Lactococcus all cause a decrease in pH of the milk to 6.5 to 4.2 after 24 hours fermentation and the LB4 strain of Lactobacillus has a strong acidifying property. This strain was used in combination with Lactococcus and Leuconostoc (CM1, CM2, CM3) gave a faster speed of acidification and a low pH. A fermented milk drink close Kefir is a highly recognized by its health and therapeutic effects beverage is then produced by the latter combination and the addition of yeast (saccharomycess cerevisiae) and acetic acid bacteria (Acetobacter). The result of this work has been a good appreciation of the new product by the tasting panel and a strong resemblance to Kefir is a Russian original product.Keywords: lactic acid bacteria, Lactobacillus, Leuconostoc, Lactococcus, Lben, Jben, Kefir

Professional Exhaustion in Teachers of higher Education: The case of USMBA teachers

A widespread phenomenon or the disease of the century, stress or commonly called “fatigue” is an increasingly popular issue. We all experience times of stress or hyperactivity, more or less intense, forcing us to tap into our energy reserves which are far from being inexhaustible. Stress is, therefore, recognized as a significant problem among teachers. In fact, the various tasks and responsibilities assigned to them regularly, the complex development of the educational system, and the health crisis linked to COVID 19, put them in situations demanding permanent efforts that undoubtedly generate stress. All these parameters are the basis of our research. Studying professional burnout among higher education teachers at Sidi Mohammed Ben Abdellah University is timely and important. The survey is meant to investigate the real mind of teachers at Moroccan University. The choice of the Likert scale is justified by our concern to bring our statistical results showing their level of stress. 60 university professors of different disciplines and different higher education institutions responded to the survey

Asymmetric hysteresis of N\'eel caps in flux-closure magnetic dots

We investigated with XMCD-PEEM magnetic imaging the magnetization reversal processes of N\'eel caps inside Bloch walls in self-assembled, micron-sized Fe(110) dots with flux-closure magnetic state. In most cases the magnetic-dependent processes are symmetric in field, as expected. However, some dots show pronounced asymmetric behaviors. Micromagnetic simulations suggest that the geometrical features (and their asymmetry) of the dots strongly affect the switching mechanism of the N\'eel caps.Comment: Proceeding for MMM-Intermag 2010 (Washington

Use of Lactococci isolated from Moroccan traditional dairy product: Development of a new starter culture

Ninety (90) strains were isolated from Moroccan traditional dairy product and identified using biochemical and molecular tests. Among the 20 identified lactic acid cocci, two strains were selected for their important acidifying activity: Lactococcus lactis subsp. lactis (AML8) and Lactococcus lactis subsp. cremoris (BML2). Both revealed remarkable acidifying activity, especially when they were mixed in cultures, even in greater values than in the traditional Lben (a Moroccan dairy product). Sensory analysis showed that the so fermented milk has been more appreciated than the Lben. These results show the potential of the two strains as possible culture starter for fermented dairy product.Keywords: Lactococci, acidifying activity, fermented milk, Lben.African Journal of Biotechnology Vol. 12(38), pp. 5662-566

Artificial Kagome Arrays of Nanomagnets: A Frozen Dipolar Spin Ice

Magnetic frustration effects in artificial kagome arrays of nanomagnets are investigated using x-ray photoemission electron microscopy and Monte Carlo simulations. Spin configurations of demagnetized networks reveal unambiguous signatures of long range, dipolar interaction between the nanomagnets. As soon as the system enters the spin ice manifold, the kagome dipolar spin ice model captures the observed physics, while the short range kagome spin ice model fails.Comment: 4 pages, 4 figures, 1 tabl