Synthesis and reactivity of a 1,4-dihydropyrazine derivative

N,N-Bis-(tert-butoxycarbonyl)-2,5-bis-methoxycarbonyl-1,4-dihydropyrazine can be obtained in high yield by treatment of the methyl ester of N-(4-toluenesulfonyl)-N-(tert-butoxycarbonyl)-alpha,beta-didehydroalanine with dimethylaminopyridine and potassium carbonate. This compound was used as substrate in Michael addition reactions with several types of nucleophiles. The electrochemical behaviour of this pyrazine derivative was also studied by cyclic voltammetry and by controlled potential electrolysis.We wish to thank the Fundação para a Ciência e a Tecnologia for financial support (project no. POCTI/1999/QUI/32689)

Lorentz-violating contributions of the Carroll-Field-Jackiw model to the CMB anisotropy

We study the finite temperature properties of the Maxwell-Carroll-Field-Jackiw (MCFJ) electrodynamics for a purely spacelike background. Starting from the associated finite temperature partition function, a modified black body spectral distribution is obtained. We thus show that, if the CMB radiation is described by this model, the spectrum presents an anisotropic angular energy density distribution. We show, at leading order, that the Lorentz-breaking contributions for the Planck's radiation law and for the Stefan-Boltzmann's law are nonlinear in frequency and quadratic in temperature, respectively. Using our results, we set up bounds for the Lorentz-breaking parameter, and show that Lorentz violation in the context of the MCFJ model is unable to yield the known CMB anisotropy (of 1 part in $10^{5})$

Ibuprofen nanocrystals: Production, lyophilization and release profile

Ibuprofen (IBU) is a poorly water-soluble non-steroidal anti-inflammatory drug with proven effectiveness for treating inflammatory, musculoskeletal, and rheumatic disorders. Nanocrystals (NCs) have been proposed as drug delivery systems to improve the solubility and bioavailability of poorly water-soluble compounds. Ibuprofen NCs (IBU-NCs) have been produced by the melt-emulsification method using a combination of Tween®80(1.0%, w/v)/Span®80(0.5%, w/v) as surfactant as these molecules are generally recognized as safe (GRAS) as non-toxic, non-irritating and are of low cost. The obtained main particle size (z-Ave) and polydispersity index (PdI) were 159.4 ± 3.265 nm and 0.24 ± 0.007, respectively. Lyophilization slightly increased the mean particle size and PdI compared to the non-freeze-dried IBU-NCs. The obtained IBU-NCs powders were of white and fine texture. The type and concentration of cryoprotector (trehalose, glucose, sucrose) influenced both the size and the in vitro release profile tested in Franz diffusion cells. Due to the smaller z-Ave, NCs:Trehalose (2:1) of 170.6 ± 3.880 nm (0.417 ± 0.050), NCs:Glucose (3:1) of 275.3 ± 8.351 nm (0.144 ± 0.021) and NCs:Sucrose (4:1) of 223.3 ± 10.35 nm (0.402 ± 0.016) were selected for the in vitro drug release tests. Within the first 6 hours, resuspended lyophilized nanocrystals released between 50-70% of the drug

Photon bubble turbulence in cold atom gases

Turbulent radiation flow is commonplace in systems with strong, incoherent, light-matter interactions. In astrophysical contexts, photon bubble turbulence is considered a key mechanism behind enhanced radiation transport, and its importance has been widely asserted for a variety of high energy objects such as accretion disks and massive stars. Here, we show that analogous conditions to those of dense astrophysical objects can be obtained in large clouds of cold atoms, prepared in a laser-cooling experiment, driven close to a sharp electronic resonance. By accessing the spatially-resolved atom density, we are able to identify a photon bubble instability and the resulting regime of photon bubble turbulence. We also develop a theoretical model describing the coupled dynamics of both photon and atom gases, which accurately describes the statistical properties of the turbulent regime. This study thus opens the possibility of simulating radiation-dominated astrophysical systems in cold atom experiments.European Union's Horizon 2020 Research and Innovation programme 820392; Portuguese Foundation for Science and Technology PD/BD/135211/2017info:eu-repo/semantics/publishedVersio

Quasi-static and dynamic photon bubbles in cold atom clouds

Turbulent radiation flow is ubiquitous in many physical systems where light–matter interaction becomes relevant. Photon bubble instabilities, in particular, have been identified as a possible source of turbulent radiation transport in astrophysical objects such as massive stars and black hole accretion disks. Here, we report on the experimental observation of a photon bubble instability in cold atomic gases, in the presence of multiple scattering of light. Two different regimes are identified, namely, the growth and formation of quasi-static structures of depleted atom density and increased photon number, akin to photon bubbles in astrophysical objects, and the destabilisation of these structures in a second regime of photon bubble turbulence. A two-fluid theory is developed to model the coupled atom–photon gas and to describe both the saturation of the instability in the regime of quasi-static bubbles and the low-frequency turbulent phase associated with the growth and collapse of photon bubbles inside the atomic sample. We also employ statistical dimensionality reduction techniques to describe the low-dimensional nature of the turbulent regime. The experimental results reported here, along with the theoretical model we have developed, may shed light on analogue photon bubble instabilities in astrophysical scenarios. Our findings are consistent with recent analyses based on spatially resolved pump–probe measurements.info:eu-repo/semantics/publishedVersio

Avaliação dos Resultados do Cross-Linking de Colagénio Corneano em Doentes com Queratocone: a Nossa Experiência

Objectivo: Avaliar os resultados visuais e queratométricos do tratamento com cross-linking de colagénio corneano (CXL) no queratocone progressivo realizado no Centro Hospitalar de Entre Douro e Vouga durante o período de 1 ano. Material e Métodos: Estudo retrospetivo no qual foram incluídos 15 olhos (15 doentes) com queratocone progressivo. Todos os pacientes foram submetidos ao tratamento com CXL com riboflavina e luz ultravioleta-A segundo o protocolo de Dresden. 8 olhos completaram 12 meses de seguimento e, 7 olhos completaram 6 meses. Avaliámos a acuidade visual com e sem correcção, cilindro refractivo e equivalente esférico, topografia corneana e paquimetria com Pentacam®, assim como os parâmetros obtidos com o Ocular Response Analyzer®. Resultados: Verificou-se uma melhoria da melhor acuidade visual corrigida média de 0.56 +/- 0.18 para 0.60 +/- 0.18 aos 3 meses, atingindo aos 6 meses 0.69, diferença estatisticamente significativa (p=0.007) e aos 12 meses 0.72 (p=0.003). Os valores do cilindro refractivo e equivalente esférico diminuíram após o procedimento mas sem significado estatístico. Em todos os olhos tratados verificou-se estabilização da progressão. A média da queratometria máxima diminui significativamente de 51.11D pré-operatório para 49.63D (p=0.002) aos 6 meses e para 50.0 D aos 12 meses (p=0.01). Conclusões: O CXL de colagénio é um tratamento promissor para o queratocone evolutivo pois permite atrasar a progressão da doença e, em alguns casos, melhorar os parâmetros visuais, refractivos e topográficos. Os nossos resultados mostram uma melhoria funcional e morfológica, com a estabilização da progressão da doença, sendo necessário, no entanto, resultados a longo prazo.info:eu-repo/semantics/publishedVersio

Positive and negative aspects of GRI reporting as perceived by Brazilian organizations

This paper aims to identify the positive and negative aspects in the sustainability reporting framework proposed by the Global Reporting Initiative (GRI). The research was conducted through content analysis of 27 companies’ responses to three questions: “Why does the company where you work prepare a sustainability report?” “What are the positive aspects you identify in the framework for GRI reporting?” and “What are the negative aspects you identify in the framework for GRI reporting?” The questionnaire was sent to all Brazilian companies that published sustainability reports using the GRI guidelines between 2011 and 2013 related to the base year 2010. We found that respondents viewed the GRI guidelines and the reports they created as management tools for sustainability and that they assist in benchmarking sustainability performance and legitimizing the sustainability actions of the organization. Furthermore, some respondents indicated that the reports themselves are marketing tools. On the other hand, the respondents reported difficulties in understanding the proposed GRI guidelines. They considered the guidelines complex, ambiguous, and too flexible, which undermined both the standardization of the reports and the ability to compare reports. Based on these comments, it is recommended that the GRI develop a simpler and less flexible reporting methodology

A mechanistic perspective on pex1 and pex6, two aaa+ proteins of the peroxisomal protein import machinery

In contrast to many protein translocases that use ATP or GTP hydrolysis as the driving force to transport proteins across biological membranes, the peroxisomal matrix protein import machinery relies on a regulated self-assembly mechanism for this purpose and uses ATP hydrolysis only to reset its components. The ATP-dependent protein complex in charge of resetting this machinery—the Receptor Export Module (REM)—comprises two members of the “ATPases Associated with diverse cellular Activities” (AAA+) family, PEX1 and PEX6, and a membrane protein that anchors the ATPases to the organelle membrane. In recent years, a large amount of data on the structure/function of the REM complex has become available. Here, we discuss the main findings and their mechanistic implications.This work was financed by FEDER—Fundo Europeu de Desenvolvimento Regional funds through the COMPETE 2020—Operacional Programme for Competitiveness and Internationalisation (POCI), Portugal 2020, and by Portuguese funds through FCT—Fundação para a Ciência e a Tecnologia/Ministério da Ciência, Tecnologia e Ensino Superior in the framework of the project PTDC/BEX-BCM/2311/2014 (POCI-01-0145-FEDER-016613) and the project “Institute for Research and Innovation in Health Sciences” (POCI-01-0145-FEDER-007274). This work is a result of the project NORTE-01-0145-FEDER-000008—Porto Neurosciences and Neurologic Disease Research Initiative at I3S, supported by Norte Portugal Regional Operational Programme (NORTE 2020), under the PORTUGAL 2020 Partnership Agreement, through the European Regional Development Fund (FEDER). A.B.-B., A.G.P., M.J.F., T.F. and T.A.R. are supported by Fundação para a Ciência e Tecnologia, Programa Operacional Potencial Humano do QREN, and Fundo Social Europeu

Volumetric and chromatic reintegration in conservation of in situ glazed tiles

Volumetric and chromatic reintegration is one of the most important but challenging treatments in conservation of in situ glazed tiles due to the need to protect them from water intrusion and further deterioration despise the demanding conditions and requirements needed in outdoor exposure. A set of six infill pastes based on aerial lime, hydraulic lime, aerial lime plus vinylic resin, epoxy resin and polyester resin binders was selected based on materials applied in previously reported interventions and the experience of professionals working in the field. The laboratory studies included the characterization of the infill pastes with and without chromatic reintegration/coating layer (SEM, MIP, porosity, water absorption, water vapour permeability, adhesion to the ceramic) and their behaviour after cure, artificial ageing (salt ageing, UV-Temp-RH cycles) and natural ageing. The results obtained allowed to formulate some considerations about these materials, their different characteristics and their performance when applied in the infill of architectural tile lacunae. The laboratory results have been compared with the performance of similar treatments surveyed on sites where they had been applied

Anaerobic biodegradability of meat-processing wastes: effect of physical, chemical and enzymatic pre-treatments

Methane is produced during the anaerobic degradation of greaves and rinds, two by-products of pig slaughter and meat-processing industry. However, although values of 914±37 and 664±35 m3 CH4 ton-1 waste (wet weight) respectively were obtained, the degradation rate in batch assays was slow and lasted between 25 and 30 days. Therefore, in order to assess the potential increase in the biodegradation rate and biodegradability of these substrates, physical (temperature), chemical (alkali) and enzymatic (lipase) pre-treatments were tested. Partial hydrolysis was achieved for all the conditions applied but the efficiency was higher in alkaline and enzymatic treatments. These conditions produced hydrolysates with higher soluble+colloidal COD, long-chain fatty acids and ammonia concentrations, comparatively with the other treatments applied. Enzymatic hydrolysis increased 14% the methane production potential of the rinds, and this increase was even higher (80%) when rinds were thermally treated before addition of the enzyme. With all other pre-treatments, anaerobic biodegradability of both wastes was not improved comparatively to the raw materials. Alkaline conditions induced a severe decreased (89%) of rinds’ biodegradability. Enzymatic pre-treatment appears to be a promising strategy for increasing methane production from meat-processing wastes