Bounds for the zeros of unilateral octonionic polynomials

In the present work it is proved that the zeros of a unilateral octo- nionic polynomial belong to the conjugacy classes of the latent roots of an appropriate lambda-matrix. This allows the use of matricial norms, and matrix norms in particular, to obtain upper and lower bounds for the zeros of unilateral octonionic polynomials. Some results valid for complex and/or matrix polynomials are extended to octonionic polyno- mials.R. Serˆodio and P. D. Beites were supported by FCT (Funda¸c˜ao para a Ciˆencia e a Tecnologia, Portugal), project UIDB/00212/2020 of CMA-UBI (Centro de Matem´atica e Aplica¸c˜oes da Universidade da Beira Interior). P. D. Beites was also supported by MINECO (Ministerio de Asuntos Econ´omicos y Transformaci´on Digital, Spain), project MTM2017-83506-C2-2-P. The authors would like to thank Maria Helena Serˆodio and Mary Garfield for clarifying some language queries.info:eu-repo/semantics/publishedVersio

Eigenvalues of matrices related to the octonions

A pseudo real matrix representation of an octonion, which is based on two real matrix represen- tations of a quaternion, is considered. We study how some operations defined on the octonions change the set of eigenvalues of the matrix obtained if these operations are performed after or before the matrix representation. The established results could be of particular interest to researchers working on estimation algorithms involving such operations.info:eu-repo/semantics/publishedVersio

Intersection of a Double Cone and a Line in the Split-Quaternions Context

This is a work on an application of the real split-quaternions to Spatial Analytic Geometry. Concretely, the intersection of a double cone and a line, which can be the empty set, a point, two points or a line, is studied in the real split-quaternions setting.MTM2013-45588-C3-1-P (Spain)info:eu-repo/semantics/publishedVersio

On skew-symmetric matrices related to the vector cross product in R^7

A study of real skew-symmetric matrices of orders 7 and 8, de ned through the vector cross product in R7, is presented. More concretely, results on matrix properties, eigenvalues, (generalized) inverses and rotation matrices are established.MTM2013-45588-C3-1-P (Spain)info:eu-repo/semantics/publishedVersio

Vector cross product differential and difference equations in R^3 and in R^7

Through a matrix approach of the 2-fold vector cross product in R^3 and in R^7, some vector cross product di erential and di erence equations are studied. Either the classical theory or convenient Drazin inverses, of elements belonging to the class of index 1 matrices, are applied.MTM2017-83506-C2-2-P (Spain)info:eu-repo/semantics/publishedVersio

MONITORAMENTO de Vancomicina em Pacientes em Tratamento Hemodialítico Com Infecções de Corrente Sanguínea Por Staphylococcus Spp

A vancomicina (van) é empiricamente prescrita para o tratamento de infecções por estafilococos em pacientes submetidos à hemodiálise (HD). O monitoramento das concentrações séricas mínimas (CSM) de van é utilizado como o mais preciso e prático método para se estimar sua eficácia, sendo recomendada a manutenção das CSM entre 10 e 20 µg/mL. O objetivo deste trabalho foi investigar as CSM de van de pacientes sob HD, em um período de dois anos e correlacioná-los com a concentração inibitória mínima (CIM) deste glicopeptídeo para Staphylococcus spp recuperados de bacteremias nestes mesmos indivíduos. As amostras recuperadas (N=80) foram testadas quanto à CIM (diluição em ágar ou caldo) de van, gentamicina (gen), oxacilina (oxa), tetraciclina (tet), rifampicina (rif), ciprofloxacino (cip), penicilina G (pen) e daptomicina (dap). Foram coletadas 101 amostras de soro de 22 pacientes em regime de administração de 1g a cada 4-5 dias, mais gen (1,5-2,0 mg/Kg) ao final de cada HD. As amostras foram coletadas antes de cada sessão de HD, nos tempos de 0, 48, 72, 96 e 120 horas após a infusão do fármaco. As CSM de van foram obtidas pelo imunoensaio de micropartículas quimioluminescentes (CMIA). Doseamento microbiológico de van foi realizado por meio da técnica pourplate com ágar sais mínimos. S. aureus foi a espécie mais frequentemente isolada (24%), seguida de Staphylococcus spp coagulase negativa (ScoN) (15%). Maiores taxas de resistência ocorreram para oxa (17% e 58%), pen (85% e 84%) e cip (26% e 45%) em S. aures e ScoN, respectivamente. Das amostras de sangue coletadas, 77,8% exibiram concentrações séricas de van <10 µg/mL e considerando apenas as coletadas imediatamente antes da próxima dose de van (CSM), 90,6% também continham concentrações inferiores àquelas recomendadas para efetiva atividade antiestafilocócica. Os valores de concentrações séricas de van obtidas pelo bioensaio apresentaram ótima correlação com o CMIA (padrão ouro) (R2 = 0,96), com valores estatísticamente similares (p<0,05) quando aplicado o fator de correção. A prevalência de Staphylococcus spp resistente à oxa sustenta o uso empírico de van, contudo, a alta taxa de isolados de S. aureus que exibiram CIM de van de 1 µg/mL (59,5%) associada às baixas CSM de van a que são submetidos a maioria dos pacientes indica chance de falha terapêutica e seleção de cepas resistentes. Assim, uma abordagem terapêutica individualizada e monitoramento da droga devem ser considerados. Para tanto foi validado o ensaio microbiológico que, pelo baixo custo e simplicidade da técnica facilita a implementação do monitoramento de van na rotina de laboratórios clínicos de pequeno porte

Caffeine degradation in leaves and fruits of Coffea arabica and Coffea dewevrei

The coffee species Coffea dewevrei and Coffea arabica have marked differences in caffeine metabolism and the control of the caffeine content during fruit ripening and leaf aging is still not clear. The aim of this work was a detailed investigation on the alkaloid degradation in young and aged leaves, and immature and mature fruits of these species. Young and aged leaves, and immature and mature fruits were fed with [2-C-14] caffeine. After an incubation period they were extracted for [2-C-14] caffeine and metabolites and analysed by reversed-phase liquid chromatography and radiocounting of collected fractions. In leaves and fruits of Coffea dewevrei there were higher degradation rates of caffeine. In both species, compared to young tissues, aged leaves and mature fruits presented lower capacity to degrade the alkaloid, what was shown by the low radioactivities detected in the metabolites formed in the degradation pathway. Radioactivity was detected in 7-methylxanthine, which is also a precursor in the caffeine biosynthesis. The data support the conclusion that the ratio between biosynthesis and biodegradation controls the variation of the caffeine content during fruit ripening and leaf aging in C. arabica and C, dewevrei.33121957196

Humoral immune response against allogeneic equine mesenchymal stem cells (MSCs) mediated by the major histocompatibility complex (MHC): an issue to take into account for the safety and efficacy of treatment with MSCs

Allogeneic mesenchymal stem cells (MSCs) present several advantages, but recipient immune response needs to be further elucidated. Proinflammatory priming of MSCs activated their in vivo regulatory capacity, but repeated administrations led to slight inflammatory reaction in an osteoarthritis equine model. This may be associated with higher major histocompatibility complex (MHC) expression, which would increase MSC immunogenicity potentially inducing humoral mediated immune memory. This study aimed at assessing allo-antibody production against donor’s equine MHC (equine leukocyte antigen, ELA) in animals that received intra-articular repeated administration of allogeneic MSC-primed. For this purpose, we used stored samples from a previous study. Donor and recipients ELA-haplotypes were stablished by microsatellite typing and complementmediated microcytoxicity assays were carried out by exposing target cells from the donor (unstimulated MSCs [MSC-nai¨ve], MSC-primed or lymphocytes [control]) to sera collected at different time-points from 10 recipients: ELA-mismatched MSCnai ¨ve recipients, ELA-mismatched MSC-primed recipients or ELA-partially matched MSC-primed recipients. All animals receiving allogeneic MSCs produced allo-antibodies after the first injection, regardless of the matching degree. However, antibody peak production after second administration was only observed in ELA-mismatched recipients, both of MSC-nai¨ve and MSCprimed. Horses injected with MSC-primed produced fewer antibodies but MSC-primed were more targeted in the microcytoxicity assay. Thus, activated immunomodulatory profile of MSC-primed could have led to slighter humoral response after ..

Pyrene coating transition metal disulfides as protection from photooxidation and environmental aging

This article belongs to the Section Nanocomposite Materials.Environmental degradation of transition metal disulfides (TMDs) is a key stumbling block in a range of applications. We show that a simple one-pot non-covalent pyrene coating process protects TMDs from both photoinduced oxidation and environmental aging. Pyrene is immobilized non-covalently on the basal plane of exfoliated MoS2 and WS2. The optical properties of TMD/pyrene are assessed via electronic absorption and fluorescence emission spectroscopy. High-resolution scanning transmission electron microscopy coupled with electron energy loss spectroscopy confirms extensive pyrene surface coverage, with density functional theory calculations suggesting a strongly bound stable parallel-stacked pyrene coverage of ~2–3 layers on the TMD surfaces. Raman spectroscopy of exfoliated TMDs while irradiating at 0.9 mW/4 μm2 under ambient conditions shows new and strong Raman bands due to oxidized states of Mo and W. Yet remarkably, under the same exposure conditions TMD/pyrene remain unperturbed. The current findings demonstrate that pyrene physisorbed on MoS2 and WS2 acts as an environmental barrier, preventing oxidative surface reactions in the TMDs catalyzed by moisture, air, and assisted by laser irradiation. Raman spectroscopy confirms that the hybrid materials stored under ambient conditions for two years remained structurally unaltered, corroborating the beneficial role of pyrene for not only hindering oxidation but also inhibiting aging.This research was funded by the European Union’s Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie grant agreement No 642742, under the “Graphene Flagship” project grant agreement No 785219 and under the ESTEEM-3 project grant agreement No 823717. This research was also partially funded by the project “Advanced Materials and Devices” (MIS 5002409), which is implemented under the “Action for the Strategic Development on the Research and Technological Sector” funded by the Operational Program “Competitiveness, Entrepreneurship and Innovation” (NSRF 2014–2020) and co-financed by Greece and the European Union (European Regional Development Fund). This work was supported by the COST Action CA15107 MultiComp. This research was also supported by the Spanish Ministerio de Economia y Competitividad (MAT2016-79776-P), from the Government of Aragon and the European Social Fund under the project “Construyendo Europa desde Aragon” 2014–2020 (grant number E13_17R).Peer reviewe