Spirulina (Arthrospira platensis) protein-rich extract as a natural emulsifier for oil-in-water emulsions: optimization through a sequential experimental design strategy

Spirulina (Arthrospira platensis) proteins have been proven to present emulsifying properties. In this work, a Spirulina protein-rich extract obtained by ultrasound extraction (SpE) was tested to stabilize oil-in-water (O/W) emulsions. For this purpose, a sequential experimental design strategy (Fractional Factorial Design (FFD) 24–1 followed by a Central Composite Rotatable Design (CCRD) 22)) was applied. The effect of four variables, SpE concentration, O/W weight ratio, pH and storage time, on emulsions’ zeta potential and number-mean droplet diameter was considered for the FFD 24–1, indicating SpE concentration and storage time as the relevant variables for the CCRD 22. According to zeta potential and number-mean droplet diameter evaluation, for the studied SpE concentration range (2–5 wt%), quite stable emulsions were obtained along the tested 30-days period. Even so, for 5%, visual inspection revealed extract segregation after 20-days. The optimal solution comprised 4 wt% of SpE, for an O/W weight ratio of 30/70 and a pH of 7.0 (number-mean droplet diameter of 55.66 nm and zeta potential of -43.83 mV). Overall, SpE has proven to be an excellent emulsifier, offering the potential to substitute animal-based proteins and synthetic emulsifiers. In addition, no signs of contamination by microorganisms were observed, suggesting that the SpE may also act as an antimicrobial agent.CIMO (Centro de Investigação de Montanha, Portugal) (UIDB/00690/2020), LSRE-LCM (Laboratory of Separation and Reaction Engineering – Laboratory of Catalysis and Materials, Portugal) (UIDB/50020/2020; UIDP/50020/2020), and ALiCE (Associate Laboratory in Chemical Engineering, Portugal) (LA/P/0045/2020), funded by national funds through Fundação para Ciência e a Tecnologia/Ministério da Ciência, Tecnologia e Ensino Superior (FCT/MCTES) (PIDDAC). National funding by Fundação para a Ciência e a Tecnologia (FCT) (Portugal), P.I., through the institutional scientific employment program contract with A. Santamaria-Echart, L. Barros, and A. Fernandes. FCT for the PhD research grant of Samara Cristina da Silva (SFRH/BD/148281/2019) and Giovana Colucci (2021. 05215. BD).info:eu-repo/semantics/publishedVersio

Spray-dried Spirulina platensis as an effective ingredient to improve yogurt formulations: testing different encapsulating solutions

The consumption of foods functionalized with spirulina might have positive health effects. However, spirulinabased food products are usually associated with unpleasant flavor and odor, and can present non-homogeneous appearance, impairing consumers’ acceptance. Moreover, it is important to assure bioactivity maintenance. To develop a novel food ingredient, spirulina was chemically characterized, and spray-dried using two encapsulating materials: i) maltodextrin and ii) maltodextrin crosslinked with citric acid. Thereafter, free and encapsulated spirulina were evaluated for their bioactive properties. Microencapsulated spirulina presented higher thermal stability than the base materials, while showing better anti-inflammatory activity without exerting cytotoxicity. Free and encapsulated spirulina were further added to yogurts to validate their suitability as functionalizing agents. Yogurts added with encapsulated spirulina presented a more homogeneous appearance, and the best solution was spirulina encapsulated in maltodextrin crosslinked with citric acid, considering the nutritional profile, attractive color, and improved antioxidant activity throughout storage time.The authors are grateful to the Foundation for Science and Technology (FCT, Portugal) and FEDER under Program PT2020 for financial support to CIMO (UID/AGR/00690/2019); L. Barros, J.C.M. Barreira, R. C. Calhelha, I.P. Fernandes and A. Fernandes thank the national funding by FCT , P.I., through the institutional scientific employment program-contract for their contracts; and C. Pereira also thanks for her contract, though the celebration of program-contract foreseen in No. 4, 5 and 6 of article 23º of Decree-Law No. 57/2016, of 29th August, amended by Law No. 57/2017, of 19th July. Associate Laboratory LSRE-LCM - UID/EQU/50020/2019 - funded by national funds through FCT/MCTES (PIDDAC), and Project NORTE- 01-0145-FEDER-000006, funded by NORTE 2020, under the PT2020 Partnership Agreement through ERDF.info:eu-repo/semantics/publishedVersio

Dynamic scaling and aging phenomena in short-range Ising spin glass: Cu0.5_{0.5}Co0.5_{0.5}Cl2_{2}-FeCl3_{3} graphite bi-intercalation compound

Static and dynamic behavior of short-range Ising-spin glass Cu$_{0.5}$Co$_{0.5}$Cl$_{2}$-FeCl$_{3}$ graphite bi-intercalation compounds (GBIC) has been studied with SQUID DC and AC magnetic susceptibility. The $T$ dependence of the zero-field relaxation time $\tau$ above a spin-freezing temperature $T_{g}$ (= 3.92 $\pm$ 0.11 K) is well described by critical slowing down. The absorption $\chi^{\prime\prime}$ below $T_{g}$ decreases with increasing angular frequency $\omega$, which is in contrast to the case of 3D Ising spin glass. The dynamic freezing temperature $T_{f}(H,\omega)$ at which d$M_{FC}(T,H)/$d$H=\chi^{\prime}(T,H=0,\omega)$, is determined as a function of frequency (0.01 Hz $\leq \omega/2\pi \leq$ 1 kHz) and magnetic field (0 $\leq H \leq$ 5 kOe). The dynamic scaling analysis of the relaxation time $\tau(T,H)$ defined as $\tau = 1/\omega$ at $T = T_{f}(H,\omega)$ suggests the absence of SG phase in the presence of $H$ (at least above 100 Oe). Dynamic scaling analysis of $\chi^{\prime \prime}(T, \omega)$ and $\tau(T,H)$ near $T_{g}$ leads to the critical exponents ($\beta$ = 0.36 $\pm$ 0.03, $\gamma$ = 3.5 $\pm$ 0.4, $\nu$ = 1.4 $\pm$ 0.2, $z$ = 6.6 $\pm$ 1.2, $\psi$ = 0.24 $\pm$ 0.02, and $\theta$ = 0.13 $\pm$ 0.02). The aging phenomenon is studied through the absorption $\chi^{\prime \prime}(\omega, t)$ below $T_{g}$. It obeys a $(\omega t)^{-b^{\prime \prime}}$ power-law decay with an exponent $b^{\prime \prime}\approx 0.15 - 0.2$. The rejuvenation effect is also observed under sufficiently large (temperature and magnetic-field) perturbations.Comment: 14 pages, 19 figures; to be published in Phys. Rev. B (September 1, 2003

Catalog of Radio Galaxies with z>0.3. I:Construction of the Sample

The procedure of the construction of a sample of distant ($z>0.3$) radio galaxies using NED, SDSS, and CATS databases for further application in statistical tests is described. The sample is assumed to be cleaned from objects with quasar properties. Primary statistical analysis of the list is performed and the regression dependence of the spectral index on redshift is found.Comment: 9 pages, 6 figures, 2 table

Search for Tensor, Vector, and Scalar Polarizations in the Stochastic Gravitational-Wave Background

The detection of gravitational waves with Advanced LIGO and Advanced Virgo has enabled novel tests of general relativity, including direct study of the polarization of gravitational waves. While general relativity allows for only two tensor gravitational-wave polarizations, general metric theories can additionally predict two vector and two scalar polarizations. The polarization of gravitational waves is encoded in the spectral shape of the stochastic gravitational-wave background, formed by the superposition of cosmological and individually unresolved astrophysical sources. Using data recorded by Advanced LIGO during its first observing run, we search for a stochastic background of generically polarized gravitational waves. We find no evidence for a background of any polarization, and place the first direct bounds on the contributions of vector and scalar polarizations to the stochastic background. Under log-uniform priors for the energy in each polarization, we limit the energy densities of tensor, vector, and scalar modes at 95% credibility to Ω0T<5.58×10-8, Ω0V<6.35×10-8, and Ω0S<1.08×10-7 at a reference frequency f0=25 Hz. © 2018 American Physical Society

FIRST SEARCHES FOR OPTICAL COUNTERPARTS TO GRAVITATIONAL-WAVE CANDIDATE EVENTS

During the LIGO and Virgo joint science runs in 2009-2010, gravitational wave (GW) data from three interferometer detectors were analyzed within minutes to select GW candidate events and infer their apparent sky positions. Target coordinates were transmitted to several telescopes for follow-up observations aimed at the detection of an associated optical transient. Images were obtained for eight such GW candidates. We present the methods used to analyze the image data as well as the transient search results. No optical transient was identified with a convincing association with any of these candidates, and none of the GW triggers showed strong evidence for being astrophysical in nature. We compare the sensitivities of these observations to several model light curves from possible sources of interest, and discuss prospects for future joint GW-optical observations of this type

On the progenitor of binary neutron star merger GW170817

On 2017 August 17 the merger of two compact objects with masses consistent with two neutron stars was discovered through gravitational-wave (GW170817), gamma-ray (GRB 170817A), and optical (SSS17a/AT 2017gfo) observations. The optical source was associated with the early-type galaxy NGC 4993 at a distance of just ∼40 Mpc, consistent with the gravitational-wave measurement, and the merger was localized to be at a projected distance of ∼2 kpc away from the galaxy's center. We use this minimal set of facts and the mass posteriors of the two neutron stars to derive the first constraints on the progenitor of GW170817 at the time of the second supernova (SN). We generate simulated progenitor populations and follow the three-dimensional kinematic evolution from binary neutron star (BNS) birth to the merger time, accounting for pre-SN galactic motion, for considerably different input distributions of the progenitor mass, pre-SN semimajor axis, and SN-kick velocity. Though not considerably tight, we find these constraints to be comparable to those for Galactic BNS progenitors. The derived constraints are very strongly influenced by the requirement of keeping the binary bound after the second SN and having the merger occur relatively close to the center of the galaxy. These constraints are insensitive to the galaxy's star formation history, provided the stellar populations are older than 1 Gyr

Microencapsulação como estratégia para a compatibilização da microalga Spirulina platensis em matrizes hidrofílicas (iogurtes).

Spirulina platensis (spirulina) é uma microalga azul esverdeada certificada pela FDA (Food and Drug Administration) como segura para ser adicionada em alimentos. Ê uma matriz rica em nutrientes como proteínas e aminoácidos, vitaminas, minerais, ácidos gordos e pigmentos [l]. No entanto, a sua adição na forma pura apresenta algumas limitações, nomeadamente presença de compostos que conferem sabor e odor indesejáveis [2] e dificuldade de dispersão em matrizes hidrofílicas. A microencapsulação é uma tecnologia que pode solucionar estes problemas sendo capaz de mascarar compostos indesejáveis e melhorar a solubilidade. Assim, o objetivo deste trabalho consistiu na caracterização de uma amostra comercial de spirulina quanto ao valor nutricional e energético, açúcares livres, ácidos gordos, tocoferóis e pigmentos e sua posterior microencapsulação pela técnica de spray-drying. Realizaram-se dois ensaios de encapsulação: i) spirulina/maltodextrina (SM) e ii) spirulina/maltodextrina reticulada com ácido cítrico (SMA), tendo-se feito a caracterização quanto ao rendimento (a eficiência e carga foram estimadas), características de degradação térmica (análise termogravimétrica (TGA/DTG)) e tamanho de partícula. Posteriormente, efetuou-se a incorporação das microesferas em iogurtes naturais, tendo-se comparado com a spirulina livre quanto à sua capacidade de homogeneização no iogurte. A microalga analisada apresentou alto teor em proteínas e cinzas. Foram identificados ácidos gordos essenciais (y-linolénico) e tocoferóis e ainda pigmentos como: β-caroteno, clorofila e a ficocianina. Esta microalga apresentou temperatura máxima de degradação de 304°C e resíduo de 27,65% a 600°C. Para a microencapsulação foi possível obter rendimentos relevantes, sendo 66% para SM e 75% para SMA'. Pela análise de TGA/DTG notou-se que as microesferas SM apresentaram duas zonas de degradação mais definidas comparativamente com SMA onde a primeira zona não é tão pronunciada. Esta situação é justificada pela ocorrência da reação de reticulação para a SMA, resultando numa melhor homogeneidade do material e um efeito de proteção superior. Notou-se que a distribuição do tamanho de partícula em volume e em número apresentaram comportamentos semelhantes para SM e SMA. Relativamente aos iogurtes observou-se uma melhor homogeneidade quando a spirulina foi adicionada na forma microencapsulada, tendo os iogurtes adicionados com spirulina livre apresentado heterogeneidade (um aspeto de efeito pontilhado) (Fig. l). Em síntese, conclui-se que a microencapsulação da bionÍassa de spirulina melhorou a compatibilidade desta microalga em matrizes hidrofílicas, tornando estes produtos de elevado valor nutricional mais atrativos para o consumidor.UID/AGR/00690/2013 (CIMO) e POCI-OI-0145-FEDER-006984 (LA LSRELCM) financiados pelo FEDER, através do POCI-COMPETE2020 e FCT; Projeto NORTE-01-0145- FEDER-000006, financiado pelo NORTE2020 e PT2020.info:eu-repo/semantics/publishedVersio

Limited engraftment capacity of bone marrow-derived mesenchymal cells following T-cell-depleted hematopoietic stem cell transplantation

The engraftment capacity of bone marrow-derived mesenchymal cells was investigated in 41 patients who had received a sex-mismatched, T-cell-depleted allograft from human leukocyte antigen (HLA) matched or -mismatched family donors. Polymerase chain reaction (PCR) analysis of the human androgen receptor (HUMARA) or the amelogenin genes was used to detect donor-derived mesenchymal cells. Only 14 marrow samples (34%) from 41 consenting patients generated a marrow stromal layer adequate for PCR analysis. Monocyte-macrophage contamination of marrow stromal layers was reduced below the levels of sensitivity of HUMARA and amelogenin assays (5% and 3%, respectively) by repeated trypsinizations and treatment with the leucyl-leucine (leu-leu) methyl ester, Patients who received allografts from 12 female donors were analyzed by means of the HUMARA assay, and in 5 of 12 cases a partial female origin of stromal cells was demonstrated. Two patients who received allografts from male donors were analyzed by amplifying the amelogenin gene, and in both cases a partial male origin of stromal cells was shown. Fluorescent in situ hybridization analysis using a Y probe confirmed the results of PCR analysis and demonstrated in 2 cases the existence of a mixed chimerism at the stromal cell level. There was no statistical difference detected between the dose of fibroblast progenitors (colony-forming unit-F [CFU-F]) infused to patients with donor- or host-derived stromal cells (1.18 +/- 0.13 x 10(4)/kg vs 1.19 +/- 0.19 x 10(4)/kg; P greater than or equal to .97). In conclusion, marrow stromal progenitors reinfused in patients receiving a T-cell-depleted allograft have a limited capacity of reconstituting marrow mesenchymal cells