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Article ; Online: Releasing antiferromagnetic skyrmions from local magnetic-anisotropy defects.

Silva, R L / Silva, R C / Pereira, A R

Journal of physics. Condensed matter : an Institute of Physics journal

2023 Volume 36, Issue 13

Abstract: Lattice defects may work as a kind of apparatus for catching topological excitations, preventing their escape. So, the problem of removing skyrmions from eventual local defects in magnetic materials must be closely related to new technologies such as ... ...

Abstract	Lattice defects may work as a kind of apparatus for catching topological excitations, preventing their escape. So, the problem of removing skyrmions from eventual local defects in magnetic materials must be closely related to new technologies such as skyrmionic. Here, we examine the conditions for drawing a skyrmion from a magnetic impurity in a two-dimensional antiferromagnetic system by applying spin-polarized currents (SPC). Two types of impurities are investigated (local easy-axis and easy-plane anisotropy defects). Also, two methods to release the skyrmion with SPC are explored. In principle, our results could be qualitatively relevant to any other type of lattice defect.
Language	English
Publishing date	2023-12-27
Publishing country	England
Document type	Journal Article
ZDB-ID	1472968-4
ISSN	1361-648X ; 0953-8984
ISSN (online)	1361-648X
ISSN	0953-8984
DOI	10.1088/1361-648X/ad162d
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Article ; Online: Magnus-force induced skyrmion-antiskyrmion coupling in inhomogeneous racetrack.

Silva, R C / Silva, R L / Pereira, A R

Journal of physics. Condensed matter : an Institute of Physics journal

2020 Volume 33, Issue 10, Page(s) 105802

Abstract: In this paper we investigate a magnetic racetrack consisting of a junction of three materials with different properties. Indeed, this magnetic system is composed by two distinct regions (racetracks) connected by a thin interface: the first region (termed ...

Abstract	In this paper we investigate a magnetic racetrack consisting of a junction of three materials with different properties. Indeed, this magnetic system is composed by two distinct regions (racetracks) connected by a thin interface: the first region (termed sector 1) has isotropic in-plane magnetic chirality and supports skyrmion (S) excitations while the second (sector 3) has anisotropic chirality and consequently supports antiskyrmions (A). The interface, which would be a third region (sector 2, connecting sectors 1 and 3) located in the central part of the racetrack, is an easy-axis Heisenberg ferromagnetic material. The topological structures S and A are put in motion by applying a spin-polarized current. Under certain conditions, we show that the skyrmion and the antiskyrmion created in their respective sectors are simultaneously impelled to the interface (due to the Magnus force) to apparently become a unique object (a skyrmion-antiskyrmion pair or SAP). After glued by sector 2, the skyrmion and the antiskyrmion move together (as a SAP) along the direction of the applied current. It is also shown that such an engineered racetrack can support a sequence of several SAP structures in motion, forming a current.
Language	English
Publishing date	2020-12-06
Publishing country	England
Document type	Journal Article
ZDB-ID	1472968-4
ISSN	1361-648X ; 0953-8984
ISSN (online)	1361-648X
ISSN	0953-8984
DOI	10.1088/1361-648X/abd1fa
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Article ; Online: Antiferromagnetic skyrmions overcoming obstacles in a racetrack.

Silva, R L / Silva, R C / Pereira, A R / Moura-Melo, W A

Journal of physics. Condensed matter : an Institute of Physics journal

2019 Volume 31, Issue 22, Page(s) 225802

Abstract: Topological objects interacting with lattice defects is an important topic in condensed matter physics. In this paper, we would like to explore the ballistic trajectory of an antiferromagnetic skyrmion in a racetrack to study processes such as collisions ...

Abstract	Topological objects interacting with lattice defects is an important topic in condensed matter physics. In this paper, we would like to explore the ballistic trajectory of an antiferromagnetic skyrmion in a racetrack to study processes such as collisions of skyrmions and holes in the magnetic sample. The skyrmion is impelled against the hole-obstacle by means of a spin polarized current. Depending on the skyrmion velocity (associated to the strength of the applied current) and the type of collision (frontal or lateral), it will be captured, scattered or completely destroyed by the hole. In some cases, this obstacle can shift the skyrmion center from a straight line to another one, and it appears as an effective way of manipulating skyrmion trajectories and dynamics.
Language	English
Publishing date	2019-02-26
Publishing country	England
Document type	Journal Article
ZDB-ID	1472968-4
ISSN	1361-648X ; 0953-8984
ISSN (online)	1361-648X
ISSN	0953-8984
DOI	10.1088/1361-648X/ab0abd
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Article: Murine model of invasive pulmonary Aspergillosis: Follow-up of tissue injury, fungal burden and mortality with distinct elastase production strains

Silva, R.L.H. / Rosa-Milani, E. / Brunaldi, M.O. / Maffei, C.M.L.

Journal de mycologie médicale. 2018 Oct. 16,

2018

Abstract: To study invasive pulmonary Aspergillosis (IPA), we depleted neutrophils in mice using the monoclonal antibody anti-Gr-1/Ly-6G. Immunocompetent and neutropenic mice were infected via intratracheal with conidia of Aspergillus fumigatus clinical isolates, ... ...

Abstract	To study invasive pulmonary Aspergillosis (IPA), we depleted neutrophils in mice using the monoclonal antibody anti-Gr-1/Ly-6G. Immunocompetent and neutropenic mice were infected via intratracheal with conidia of Aspergillus fumigatus clinical isolates, characterized as either higher or lower elastase producers. Neutropenic animals exhibited 100% mortality in 5 days, for both strains, and were observed survival curves overlapped, lungs with angioinvasion, rupture of bronchial and vascular walls, associated with exuberance of conidia filamentation. The immunocompetent animals infected with the lower elastase producer strain presented with upregulated inflammatory processes, and a lack of conidia filamentation in the tissue. The fungal burden in the lungs was not different in the immunocompetent and neutropenic groups. These findings confirm the protective role of neutrophils against A. fumigatus and suggest that the fungal elastinolytic activity is not a critical virulence factor but may be involved in tissue injury.
Keywords	Aspergillus fumigatus ; animal models ; aspergillosis ; conidia ; elastase ; fungi ; monoclonal antibodies ; mortality ; neutrophils ; protective effect ; virulence
Language	English
Dates of publication	2018-1016
Publishing place	Elsevier Masson SAS
Document type	Article
Note	Pre-press version
ZDB-ID	1067006-3
ISSN	1156-5233
ISSN	1156-5233
DOI	10.1016/j.mycmed.2018.10.003
Database	NAL-Catalogue (AGRICOLA)

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Article ; Online: Antibacterial activity of Thymus vulgaris (thyme) essential oil against strains of Pseudomonas aeruginosa, Klebsiella pneumoniae and Staphylococcus saprophyticus isolated from meat product.

Diniz, A F / Santos, B / Nóbrega, L M M O / Santos, V R L / Mariz, W S / Cruz, P S C / Nóbrega, R O / Silva, R L / Paula, A F R / Santos, J R D A / Pessôa, H L F / Oliveira-Filho, A A

Brazilian journal of biology = Revista brasleira de biologia

2023 Volume 83, Page(s) e275306

Abstract: Meat products represent an important component of the human diet and are a good source of nutrients. Food-borne microorganisms are the main pathogens that cause human diseases as a result of food consumption, especially products of animal origin. The ... ...

Abstract	Meat products represent an important component of the human diet and are a good source of nutrients. Food-borne microorganisms are the main pathogens that cause human diseases as a result of food consumption, especially products of animal origin. The objective of the present research was to verify the antibacterial activity of the essential oil of Thymus vulgaris against strains of Klebsiella pneumoniae, Pseudomonas aeruginosa and Staphylococcus saprophyticus isolated from meat products. For this, the analyses of Minimum Inhibitory Concentration (MIC) and Minimum Bactericidal Concentration (MBC) were performed in microdilution plates. The association of the product with antimicrobials was also studied using disk diffusion. And the anti-adherent activity, which was determined in the presence of sucrose, in glass tubes. Thyme oil showed a strong inhibitory activity against K. pneumoniae, P. aeruginosa and S. saprophyticus, with the MIC values ranging from 64 to 512 μg/mL, and bactericidal effect for most strains, with MBC values ranging from 256 to 1,024 μg/mL. T. vulgaris oil exhibited varied interactions in association with the antimicrobials, with synergistic (41.67%), indifferent (50%) and antagonistic (8.33%) effects. Regarding the anti-adherent activity, the test product was effective in inhibiting the adherence of all bacterial strains under study. Therefore, thyme oil presents itself as an antibacterial and anti-adherent agent against K. pneumoniae, P. aeruginosa and S. saprophyticus, being a natural product that can represent an interesting alternative in the efforts to combat foodborne diseases.
MeSH term(s)	Animals ; Humans ; Oils, Volatile/pharmacology ; Thymus Plant ; Pseudomonas aeruginosa ; Klebsiella pneumoniae ; Staphylococcus saprophyticus ; Meat Products ; Anti-Bacterial Agents/pharmacology ; Anti-Infective Agents/pharmacology ; Microbial Sensitivity Tests
Chemical Substances	Oils, Volatile ; thyme oil (2UK410MY6B) ; Anti-Bacterial Agents ; Anti-Infective Agents
Language	English
Publishing date	2023-08-11
Publishing country	Brazil
Document type	Journal Article
ZDB-ID	2036257-2
ISSN	1678-4375 ; 1519-6984
ISSN (online)	1678-4375
ISSN	1519-6984
DOI	10.1590/1519-6984.275306
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Article: Conservation, propagation and new paths for pineapple genetic resources

Souza, F. V. D / Ferreira, F. R / Souza, E. H / Silva, R. L / Guerra, P. A

Acta horticulturae. 2019 Apr. 30, , no. 1239

2019

Abstract: The Embrapa Cassava and Fruits research unit (Embrapa Mandioca e Fruticultura) maintains in its experimental fields a pineapple active germplasm bank (AGB Pineapple) with 700 accessions of the genus Ananas. In recent years, several of these accessions, ... ...

Abstract	The Embrapa Cassava and Fruits research unit (Embrapa Mandioca e Fruticultura) maintains in its experimental fields a pineapple active germplasm bank (AGB Pineapple) with 700 accessions of the genus Ananas. In recent years, several of these accessions, of all botanical varieties, have been lost as a result of infection by the Pineapple mealybug wilt-associated virus complex (PMWaV). Because of this threat, the establishment of security duplicates is a priority for the managers of AGB Pineapple, to minimize losses in the field as well as to increase the efficiency of preservation. Two strategies to preserve this germplasm have been used in recent years: in vitro conservation and cryopreservation. This work will cover the limitations of the two techniques and in particular the advances achieved, and proposals being analysed for better conservation of this important germplasm. It will also cover the efficiency of propagation techniques, the precautions that need to be considered and their convergence with preservation and genetic improvement of pineapple species. Finally, the creation of a global collaborative structure for genetic resources of the genus Ananas will be discussed, for the purpose of assuring their conservation by different strategies, based on cooperation, to facilitate use of the conservation methods by researchers in several countries.
Keywords	Ananas ; Manihot ; Pineapple mealybug wilt-associated virus ; cassava ; cryopreservation ; field experimentation ; fruits ; genetic improvement ; germplasm ; pineapples
Language	English
Dates of publication	2019-0430
Size	p. 105-112.
Publishing place	International Society for Horticultural Science.
Document type	Article
Note	Paper presented at the IX International Pineapple Symposium held October 15 - October 19, 2017, Havana, Cuba
ISSN	0567-7572
DOI	10.17660/ActaHortic.2019.1239.13
Database	NAL-Catalogue (AGRICOLA)

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Article ; Online: Murine model of invasive pulmonary Aspergillosis: Follow-up of tissue injury, fungal burden and mortality with distinct elastase production strains.

Silva, R L H / Rosa-Milani, E / Brunaldi, M O / Maffei, C M L

Journal de mycologie medicale

2018 Volume 29, Issue 2, Page(s) 112–119

Abstract	To study invasive pulmonary Aspergillosis (IPA), we depleted neutrophils in mice using the monoclonal antibody anti-Gr-1/Ly-6G. Immunocompetent and neutropenic mice were infected via intratracheal with conidia of Aspergillus fumigatus clinical isolates, characterized as either higher or lower elastase producers. Neutropenic animals exhibited 100% mortality in 5 days, for both strains, and were observed survival curves overlapped, lungs with angioinvasion, rupture of bronchial and vascular walls, associated with exuberance of conidia filamentation. The immunocompetent animals infected with the lower elastase producer strain presented with upregulated inflammatory processes, and a lack of conidia filamentation in the tissue. The fungal burden in the lungs was not different in the immunocompetent and neutropenic groups. These findings confirm the protective role of neutrophils against A. fumigatus and suggest that the fungal elastinolytic activity is not a critical virulence factor but may be involved in tissue injury.
MeSH term(s)	Animals ; Aspergillus fumigatus/enzymology ; Aspergillus fumigatus/isolation & purification ; Bronchi/microbiology ; Bronchi/pathology ; Disease Models, Animal ; Humans ; Invasive Pulmonary Aspergillosis/microbiology ; Invasive Pulmonary Aspergillosis/mortality ; Invasive Pulmonary Aspergillosis/pathology ; Lung/microbiology ; Lung/pathology ; Male ; Mice ; Mice, Inbred C57BL ; Neutropenia ; Neutrophils/immunology ; Pancreatic Elastase/metabolism ; Spores, Fungal/isolation & purification ; Spores, Fungal/physiology
Chemical Substances	Pancreatic Elastase (EC 3.4.21.36)
Language	English
Publishing date	2018-11-13
Publishing country	France
Document type	Journal Article
ZDB-ID	1067006-3
ISSN	1773-0449 ; 1156-5233
ISSN (online)	1773-0449
ISSN	1156-5233
DOI	10.1016/j.mycmed.2018.10.003
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Book ; Online: Skyrmion bound state and dynamics in an antiferromagnetic bilayer racetrack

Silva, R. C. / Silva, R. L. / Carvalho-Santos, V. L. / Moura-Melo, W. A. / Pereira, A. R.

2021

Abstract: We investigate the dynamics of two skyrmions lying in distinct layers of an antiferromagnetic bilayer system, consisting of nanostripes with the shape of racetracks. The top and bottom nanostripes are separated by a height offset and they are coupled ... ...

Abstract	We investigate the dynamics of two skyrmions lying in distinct layers of an antiferromagnetic bilayer system, consisting of nanostripes with the shape of racetracks. The top and bottom nanostripes are separated by a height offset and they are coupled through a ferromagnetic exchange, allowing the interaction between the skyrmions from both layers. Depending on the distance between the skyrmions they attract each other sufficiently to achieve a bound state. We also analyze their dynamics when an electric current is applied in a unique layer and we determine how the bound-state nucleation depends on the current density and vertical distance between the skyrmions. Finally, we analyzed the robustness of the bound states by considering two situations: 1) a system constituted by clean or homogeneous antiferromagnetic racetracks; 2) a system in which randomly distributed magnetic impurities in both layers are included in the system. Comment: 8 pages, 7 figures
Keywords	Condensed Matter - Mesoscale and Nanoscale Physics ; Condensed Matter - Strongly Correlated Electrons
Subject code	612
Publishing date	2021-09-09
Publishing country	us
Document type	Book ; Online
Database	BASE - Bielefeld Academic Search Engine (life sciences selection)

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Article: An Early Jurassic (Sinemurian–Toarcian) stratigraphic framework for the occurrence of Organic Matter Preservation Intervals (OMPIs)

Silva, R.L. / Duarte, L.V. / Wach, G.D. / Ruhl, M. / Sadki, D. / Gómez, J.J. / Hesselbo, S.P. / Xu, Weimu / O'Connor, D. / Rodrigues, B. / Filho, J.G. Mendonça

Earth-science reviews. 2021 Oct., v. 221

2021

Abstract: Lower Jurassic sedimentary successions in the Atlantic margin basins include several organic-rich intervals, some with source rock potential; time-equivalent units are also identified in on- and offshore areas worldwide. Despite decades of research, it ... ...

Abstract	Lower Jurassic sedimentary successions in the Atlantic margin basins include several organic-rich intervals, some with source rock potential; time-equivalent units are also identified in on- and offshore areas worldwide. Despite decades of research, it is still unclear which mechanisms lead to the deposition of organic-rich sediments during the Early Jurassic. The objectives of this study are to construct a detailed temporal and geographical framework of Sinemurian–Toarcian organic matter preservation intervals (OMPIs; subdivided into local, regional, and superregional) and roughly constrain the relationship of OMPIs with the Lower Jurassic δ¹³C record. This survey combines an in-depth analysis of literature on the distribution of organic-rich facies in the Sinemurian–Toarcian with new geochemical studies [total organic carbon (TOC) and organic matter pyrolysis] from selected outcrop sections from Portugal, Spain, and Morocco.Strong local control on OMPIs during most of the Sinemurian is suggested. Regionally widespread organic-rich facies are associated with the most negative δ¹³C values of the broad Sinemurian–Pliensbachian negative carbon isotopic trend recorded in organic matter (including the Sinemurian–Pliensbachian Boundary Event). Pliensbachian OMPIs are expressive in the areas bordering the proto-Atlantic Ocean and are often linked with positive δ¹³C excursions and short-lived warm intervals, but OMPIs are also defined for the Late Pliensbachian cool interval. Early Toarcian superregional OMPIs are associated with some of the most pronounced δ¹³C excursions of the Mesozoic. Toarcian maximum TOC content occurs with the positive δ¹³C (recovery) trend following the δ¹³C negative shift typically linked with the Early Toarcian Oceanic Anoxic Event (T-OAE), supporting the notion that peak carbon sequestration/ocean anoxia post-dated the main phase of carbon input into the atmosphere, as also suggested by recent modelling efforts. However, additional superregional OMPIs predate and postdate the T-OAE, indicating that conditions favouring preservation of organic matter (increased productivity and/or enhanced preservation) during the Early Toarcian were not restricted to the T-OAE interval.The compilation of Sinemurian–Toarcian OMPIs presented in this paper demonstrates that organic-rich intervals of regional and superregional expression in the Lower Jurassic sedimentary record are ubiquitous and may even be more numerous than in the Cretaceous. Considering the association of some of the Sinemurian, Pliensbachian, and Toarcian (not taking into account the T-OAE related OMPIs) regional and superregional OMPIs with well-defined carbon isotopic excursions, it is here suggested that these hold the same relevance as the secondary OAEs of the Cretaceous, such as the Valanginian OAE (Weissert Event), Hauterivian OAE (Faraoni Event), and Late Aptian–Early Albian OAE (OAE 1b cluster).
Keywords	Cretaceous period ; Pliensbachian age ; Sinemurian age ; Toarcian age ; anaerobic conditions ; carbon sequestration ; pyrolysis ; surveys ; total organic carbon ; Portugal ; Spain
Language	English
Dates of publication	2021-10
Publishing place	Elsevier B.V.
Document type	Article
ZDB-ID	1792-9
ISSN	0012-8252
ISSN	0012-8252
DOI	10.1016/j.earscirev.2021.103780
Database	NAL-Catalogue (AGRICOLA)

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Article ; Online: Effects of second neighbor interactions on skyrmion lattices in chiral magnets.

Oliveira, E A S / Silva, R L / Silva, R C / Pereira, A R

Journal of physics. Condensed matter : an Institute of Physics journal

2017 Volume 29, Issue 20, Page(s) 205801

Abstract: In this paper we investigate the influences of the second neighbor interactions on a skyrmion lattice in two-dimensional chiral magnets. Such a system contains the exchange and the Dzyaloshinskii-Moriya for the spin interactions and therefore, we analyse ...

Abstract	In this paper we investigate the influences of the second neighbor interactions on a skyrmion lattice in two-dimensional chiral magnets. Such a system contains the exchange and the Dzyaloshinskii-Moriya for the spin interactions and therefore, we analyse three situations: firstly, the second neighbor interaction is present only in the exchange coupling; secondly, it is present only in the Dzyaloshinskii-Moriya coupling. Finally, the second neighbor interactions are present in both exchange and Dzyaloshinskii-Moriya couplings. We show that such effects cause important modifications to the helical and skyrmion phases when an external magnetic field is applied.
Language	English
Publishing date	2017-05-24
Publishing country	England
Document type	Journal Article
ZDB-ID	1472968-4
ISSN	1361-648X ; 0953-8984
ISSN (online)	1361-648X
ISSN	0953-8984
DOI	10.1088/1361-648X/aa63dd
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