Tuning the antiferromagnetic easy axis direction in exchange bias bilayers

Abstract The exchange bias effect is measured for a Co/NiO bilayer before and after it has been cooled down from 580 K in 1.5 kOe magnetic field applied at 45 to the initial exchange-bias direction. The angular variation of the hysteresis loop shift for the treated sample showed three distinct minima and maxima, in contrast to that of the as-made sample, which is characteristic for a system with aligned ferromagnetic and antiferromagnetic easy axes. This behavior is qualitatively well explained in the framework of the domain-wall formation model applied for the off-aligned case. The continued interest in the exchange-bias effect, which results from the interfacial coupling between ferromagnetic (FM) and antiferromagnetic (AF) materials, is motivated by fundamental and technological interests. In almost all of the model works, the direction of the easy axis of the AF layer is aligned with the FM one; some numerical calculations using a simple StonerWohlfarth model for the case of ''off-aligned'' coupling have been done by Xi and White In the present work, a FM/AF bilayer was deposited by magnetron sputtering onto Si(1 0 0) substrate at room temperature (RT) in 2.0 mTorr Ar atmosphere with base pressure before depositing better than 5 Â 10 À8 Torr. The film consists of 30 nm Co deposited on 50 nm NiO and capped with 5 nm Cu in order to prevent oxidation in air. Magnetic field of 0.5 kOe has been applied during the deposition. The structural characterization, made via conventional X-ray diffractometry performed on a Philips X'Pert MRD machine employing Cu Ka radiation, showed that the Co layer is strongly (2 2 0) textured, whereas the NiO contribution is a combination of evenly divided (1 1 1) and (2 0 0) NiO textures. In-plane RT hysteresis loops were obtained by using an alternating gradient force magnetometer. No training effect, i.e., dependence of the hysteresis loop field shift, H eb ; on repeated magnetization reversal, has been observed. The sample was heated to 580 K, which is higher than the NiO N! eel temperature of 520 K but rather lower than the Curie temperature of Co, and then cooled down to RT in the presence of a magnetic field of 1.5 kOe applied at 45 (75) to the initial exchange-bias direction. Once again, effects of training have not been detected

Nitrogen diffusion enhancement in a ferrous alloy by deuterium isotopic effect

Studies of nitrogen implantation in an iron alloy using photoemission electron spectroscopy, sputtered neutral mass spectrometry, and elastic recoil detection analysis, reveal an enhancement of nitrogen diffusion when deuterium replaces hydrogen in the gas. Compared to hydrogen, deuterium reduces NOx species on the surface (geometric barrier), increasing the nitrogen activity at the surface and consequently nitrogen diffusion into the solid solution. (c) 2007 American Institute of Physics.1011

Thermal stability of plasma-nitrided aluminum oxide films on Si

The effect of post-deposition rapid thermal annealing in vacuum and in dry O2 on the stability of remote plasma-assisted nitrided aluminum oxide films on silicon is investigated. The areal densities of Al, O, N, and Si were determined by nuclear reaction analysis and their concentration versus depth distributions by narrow nuclear reaction resonance profiling, with subnanometric depth resolution. Annealing in both vacuum and O2 atmospheres produced partial loss of N from the near-surface regions of the films and its transport into near-interface regions of the Si substrate. Oxygen from the gas phase was incorporated in the AlON films in exchange for O and N previously existing therein, as well as in the near-interface regions of the Si substrate, leading to oxynitridation of the substrate. Al and Si remained essentially immobile under rapid thermal processing, confirming that the presence of nitrogen improves the thermal stability characteristics of the AlON/ Si structures in comparison with non-nitrided Al2O3 /Si

Infections with Avian Pathogenic and Fecal Escherichia coli Strains Display Similar Lung Histopathology and Macrophage Apoptosis

The purpose of this study was to compare histopathological changes in the lungs of chickens infected with avian pathogenic (APEC) and avian fecal (Afecal) Escherichia coli strains, and to analyze how the interaction of the bacteria with avian macrophages relates to the outcome of the infection. Chickens were infected intratracheally with three APEC strains, MT78, IMT5155, and UEL17, and one non-pathogenic Afecal strain, IMT5104. The pathogenicity of the strains was assessed by isolating bacteria from lungs, kidneys, and spleens at 24 h post-infection (p.i.). Lungs were examined for histopathological changes at 12, 18, and 24 h p.i. Serial lung sections were stained with hematoxylin and eosin (HE), terminal deoxynucleotidyl dUTP nick end labeling (TUNEL) for detection of apoptotic cells, and an anti-O2 antibody for detection of MT78 and IMT5155. UEL17 and IMT5104 did not cause systemic infections and the extents of lung colonization were two orders of magnitude lower than for the septicemic strains MT78 and IMT5155, yet all four strains caused the same extent of inflammation in the lungs. The inflammation was localized; there were some congested areas next to unaffected areas. Only the inflamed regions became labeled with anti-O2 antibody. TUNEL labeling revealed the presence of apoptotic cells at 12 h p.i in the inflamed regions only, and before any necrotic foci could be seen. The TUNEL-positive cells were very likely dying heterophils, as evidenced by the purulent inflammation. Some of the dying cells observed in avian lungs in situ may also be macrophages, since all four avian E. coli induced caspase 3/7 activation in monolayers of HD11 avian macrophages. In summary, both pathogenic and non-pathogenic fecal strains of avian E. coli produce focal infections in the avian lung, and these are accompanied by inflammation and cell death in the infected areas

Caracterização patológica, microbiológica e imuno-histoquímica de colibacilose em frangos de corte de Moçambique

Avian colibacillosis is an acute and globally occurring infectious disease of domestic and wild birds caused by Escherichia coli, and it is associated with considerable economic losses mainly due to the morbidity and mortality associated. The present study aimed to describe the pathological, bacteriological and immunohistochemical aspects of avian colibacillosis in broiler chickens of Mozambique. Forty-nine broiler chicken presented anorexia, decreased weight gain, ataxia, diarrhea, dyspnea, and death in a clinical course of 3-5 days. The birds were raised in five farms (small, medium and large farms) with manual and automatic breeding system, with flocks ranging from 100 to 20,000 birds. At the necropsy, all birds had poor body condition, and the pericardium and the Glisson’s capsule of all avian exhibited different degrees of adherence often associated with severe fibrin deposition. The thoracic and abdominal air sacs were thickened and adhered to the costal wall. Mild, moderate or marked hepatomegaly associated with white pinpoint multifocal areas (100%, 49/49) and mild to moderate splenomegaly in 75.5% (37/49) with a mottled surface were observed. The lungs and kidney were enlarged and reddish. Histologically, a multiorgan fibrinoheterophilic polyserositis was observed in 75.5% of the cases (37/49), which were characterized by inflammatory infiltrates composed mainly of degenerative heterophils, macrophages and plasma cells, associated with fibrin deposits and intermixed by coccobacillary bacterial basophilic aggregates. These affected mainly the pericardium (28.6%, 14/49), the pleura (18.4%, 9/49), the Glisson’s capsule (10.2%, 5/49), the ventriculus (10.2, 5/33), and the proventriculus (8.2%, 4/49) serosa. Multifocal to coalescing areas of coagulative necrosis associated with similar inflammatory cells were observed mainly in the spleen (28.6%, 14/49), liver (24.5%, 12/49), and intestines (22.4%, 11/49). A similar infiltrate was also observed affecting the the lungs (16.3%, 8/49), the kidney (16.3%, 8/49) and the myocardium (14.3%, 7/49). Isolation and identification of E. coli was obtained in 12 cases through bacterial culture. Some organs (2 cases of each farms) were selected and submitted to immunohistochemistry anti-E. coli, and a positive stain was observed in all tested cases in liver (3/3), heart (4/4), spleen (1/1), lungs (4/4), intestines (4/4), bursa of Fabricius (1/1), ventriculus (1/1), and proventriculus (1/1) tissue sections. These results demonstrate that E. coli was the cause of mortality in these birds. Therefore, biosecurity and management measures should be employed to prevent and control the disease occurrence in Mozambique’s poultry farming.A colibacilose aviária é uma doença aguda de ocorrência mundial que acomete aves domésticas e silvestres, causada por Escherichia coli e resulta em perdas econômicas consideráveis devido à elevada morbidade e mortalidade das aves. O presente estudo teve o objetivo de descrever os aspectos patológicos, bacteriológicos e imuno-histoquímicos de colibacilose aviária em frangos de corte de Moçambique. Um total de 49 frangos de corte apresentaram anorexia, baixo ganho de peso, ataxia, diarreia, dispneia e morte em um curso clínico de 3 a 5 dias. As aves eram provenientes de 5 granjas (pequenas, média e grandes), com sistema de criação manual e automático, com rebanhos que variavam de 100 a 20.000 aves. À necropsia, todas as aves exibiam condição corporal ruim a caquética, além de pericárdio e cápsula de Glisson de todas aves (100%; n=49) com diferentes graus de aderência e deposição de fibrina de forma difusa acentuada. Os sacos aéreos torácicos e abdominais estavam espessados e aderidos à parede costal. Foi observado ainda hepatomegalia discreta, moderada a severa frequentemente associada com áreas multifocais puntiformes brancacentas (100%; 49/49), e esplenomegalia discreta a moderada, associado a áreas multifocais moteadas (75,5%; 37/49). Os pulmões e rins estavam aumentados e com coloração avermelhada. Histologicamente, observou-se majoritariamente serosite fibrinoheterofílica em 75,5% dos casos (37/49), caracterizadas por infiltrado inflamatório composto por heterófilos degenerados, macrófagos, linfócitos e plasmócitos, com deposição de fibrina entremeada por uma miríade de estruturas bacterianas cocobacilares. Esta lesão foi observada principalmente em pericárdio (28,6%; 14/49), pleura (18,4%; 9/49), cápsula de Glisson (10,2%; 5/49), ventrículo (10,2; 5/33) e em proventrículo (8,2%; 4/49). Áreas multifocais a coalescentes de necrose de coagulação associada a infiltrado inflamatório semelhante ao descrito foi observado principalmente no baço (28,6%; 14/49), fígado (24.5%; 12/49), e intestinos (8,2%; 4/49). Um infiltrado inflamatório semelhante também foi visualizado em pulmões (16,3%; 8/49), rins (16,3%; 8/49) e miocárdio (14,3%; 7/49), Colônias puras de E. coli foram identificadas e isoladas em 12 casos. Alguns órgãos (2 de cada granja) foram submetidos ao exame imuno-histoquímico anti-E. coli e marcação positiva foi visualizada em todos casos testados, como em fígado (3/3), coração (4/4), baço (1/1), pulmão (4/4), intestinos (4/4), bursa de Fabricius (1/1), rim (1/1), ventrículo (1/1) e proventrículo (1/1). Estes resultados demonstram que E. coli foi a causa de morte destas aves. Sendo assim, a adoção de boas medidas de biosseguridade e de manejo são indispensáveis para a prevenção e controle da ocorrência da doença nas granjas de frango de corte de Moçambique

Influenza A virus infection in pigs from Mozambique

Swine  influenza  (SI)  is  an  acute  and  highly  contagious  disease  of  the  respiratory tract of pigs caused by swine influenza A virus (SIA). The disease causes economic losses in swine production and is of great public importance for its zoonotic potential. The aims of the present  study  were  to  report SIA infection  in  pigs  from  Mozambique  and  characterize  the anatomopathological  and  immunohistochemical  features  of  associated  lung  lesions.  Lungs from  457  slaughtered  pigs  were  subjected  to  gross  evaluation  and 38  (8.3%)  lungs  with cranioventral  consolidation  were  collected  from  a slaughterhouse  in  Matola  City,  Southern Mozambique. Consolidation areas in each lung lobe  were classified in 4 grades according to the lesion extension. Samples with consolidated lung tissue were examined for histopathology and  immunohistochemistry  for  the  presence  of  SIA,  Porcine  circovirus  type  2  (PCV2)  and Mycoplasma  hyopneumoniae  antigens.  The  lungs  had  multifocal  to  coalescing  areas  of consolidation observed most frequently in the craniallobes. The lesions involved mainly one or three  pulmonary  lobes  and  grade  1  and  2  lesions  were  the  most  frequent.  The  main histopathological  findings  were  necrotizing  bronchiolitis  (23/38),  alveolar  neutrophil infiltration (24/38), type II pneumocytes hyperplasia (26/38), peribronchiolar lymphoid tissue hyperplasia  (28/38)  and  interstitial  mononuclear  cells  infiltrate  (29/38). SIA  antigen  was detected by immunohistochemistryin 84.3% (32/38) of lung samples and all lung samples were negative  for  PCV2  and Mycoplasma  hyopneumoniaantigense. Pigs  that  presented  a  positive result on IHQ were from Matutuine district (5/32), Moamba district (2/32), Namaacha district (21/32), Boane district (3/32) and Matola city (1/32). These results demonstrate that SIA is a cause of pneumonia in pigs in Mozambique

Aplicação de espectrometria de massas MALDI-TOF para identificação de candidatos a marcadores moleculares de Scrapie.

O trabalho aqui apresentado busca identificar marcadores moleculares para diagnóstico de Scrapie em amostras de sangue de animais acometidos por PrPSc

Golgi-localized STELLO proteins regulate the assembly and trafficking of cellulose synthase complexes in Arabidopsis.

As the most abundant biopolymer on Earth, cellulose is a key structural component of the plant cell wall. Cellulose is produced at the plasma membrane by cellulose synthase (CesA) complexes (CSCs), which are assembled in the endomembrane system and trafficked to the plasma membrane. While several proteins that affect CesA activity have been identified, components that regulate CSC assembly and trafficking remain unknown. Here we show that STELLO1 and 2 are Golgi-localized proteins that can interact with CesAs and control cellulose quantity. In the absence of STELLO function, the spatial distribution within the Golgi, secretion and activity of the CSCs are impaired indicating a central role of the STELLO proteins in CSC assembly. Point mutations in the predicted catalytic domains of the STELLO proteins indicate that they are glycosyltransferases facing the Golgi lumen. Hence, we have uncovered proteins that regulate CSC assembly in the plant Golgi apparatus.The work presented in this paper was supported by grants from the BBSRC: BB/G016240/1 BBSRC Sustainable Energy Centre Cell Wall Sugars Programme (BSBEC) and the European Community’s Seventh Framework Programme SUNLIBB (FP7/2007-2013) under the grant agreement n° 251132 to PD. The UK 850 MHz solid-state NMR Facility was funded by EPSRC and BBSRC, as well as the University of Warwick including via part funding through Birmingham Science City Advanced Materials Projects 1 and 2 supported by Advantage West Midlands (AWM) and the European Regional Development Fund (ERDF); we thank Dinu Iuga for experimental assistance, and Chris Somerville for helpful discussions and suggesting the name STELLO. The authors acknowledge LNBio and LNLS for providing X-ray beam time (proposal GAR 15208), and the Sainsbury Laboratory Cambridge University for imaging facilities. TV was supported by an EMBO long-term fellowship (ALTF 711-2012) and by postdoctoral funding from the Philomathia Foundation. HEM was supported by an EMBO Long Term Fellowship (ALTF-1246-2013) and an NSERC Postdoctoral Fellowship (PDF-454454-2014). SP and YZ were supported by the Max-Planck Gesellschaft, and SP was also supported by a R@MAP Professor position at UoM. We thank the Biological Optical Microscopy Platform (BOMP) at University of Melbourne, and Tom Simmons and Rita Marques for assistance on sugar analyses.This is the final version of the article. It first appeared from Nature Publishing Group via http://dx.doi.org/10.1038/ncomms11656

Identificação do BVDV em bovinos pela técnica de imunoistoquímica

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