The magnetic Purcell effect: the case of an emitter near an antiferromagnet

In this paper we discuss the magnetic Purcell effect of a magnetic dipole near a semi-infinite antiferromagnet. Contrary to the electric Purcell effect, the magnetic one is not so well studied in the literature. We derive the dispersion relation of the surface wave existing at an antiferromagnetic-dielectric interface from the calculation of the reflection coefficient of the structure. After characterizing the surface wave we quantize the electromagnetic vector potential of the surface wave. This allows us to discuss the magnetic Purcell effect via the Fermi golden rule. Copyright (C) EPLA, 2019- BAF and NMRP acknowledge discussions on the topic of this paper with Bruno Amorim and Gil Farias, and the Center of Physics of the University of Minho and the University of Porto for funding in the framework of the Strategic Financing UID/FIS/04650/2013. NMRP acknowledges support from the European Commission through the project "Graphene-Driven Revolutions in ICT and Beyond" (Ref. No. 785219), COMPETE2020, PORTUGAL2020, FEDER and the Portuguese Foundation for Science and Technology (FCT) through project POCI-01-0145-FEDER-028114

Could fruits be a reliable source of food colorants? Pros and cons of these natural additives

Color additives are important for the food industry to improve sensory quality lost during food process and to expand the variety of products. In general, artificial colorants have lower cost and better stability than the natural ones. Nevertheless, studies have reported their association with some health disorders. Furthermore, consumers have given greater attention to food products with health beneficial effects, which has provided a new perspective for the use of natural colorants. In this context, fruits are an excellent alternative source of natural compounds, that allow the obtainment of a wide range of colorant molecules, such as anthocyanins, betalains, carotenoids, and chlorophylls. Furthermore, in addition to their coloring ability, they comprise different bioactive properties. However, the extraction and application of natural colorants from fruits is still a challenge, since these compounds show some stability problems, in addition to issues related to the sustainability of raw-materials providing. To overcome these limitations, several studies have reported optimized extraction and stabilization procedures. In this review, the major pigments found in fruits and their extraction and stabilization techniques for uses as food additives will be looked over.The authors are grateful to the Foundation for Science and Technology (FCT, Portugal) and FEDER under Programme PT2020 for financial support to CIMO (UID/AGR/00690/2013), L. Barros contract. To: The authors are grateful to the Foundation for Science and Technology (FCT, Portugal) for financial support through national funds FCT/MCTES to CIMO (UIDB/00690/2020); L. Barros thanks the national funding by FCT, P.I., through the institutional scientific employment program-contract.info:eu-repo/semantics/publishedVersio

Quantization of graphene plasmons

In this article we perform the quantization of graphene plasmons using both a macroscopic approach, based on the classical expression for the average electromagnetic energy in a dielectric medium, and a quantum hydrodynamic model, in which graphene electrons are modeled as a charged fluid. Both models allow one to take into account the dispersion in the optical response, with the hydrodynamic model also allowing for the inclusion of the momentum dependence of the optical response (nonlocal effects). Using both methods, the electromagnetic field mode functions, and the respective frequencies, are determined for two different graphene structures. We show how to quantize graphene plasmons, considering that graphene is a dispersive medium, within the local and nonlocal descriptions. It is found that the dispersion of graphene's optical response leads to a nontrivial normalization condition for the mode functions. The obtained mode functions are then used to calculate the decay of an emitter, represented by a dipole, via the excitation of graphene surface plasmon polaritons. The obtained results are compared with the total spontaneous decay rate of the emitter and a near perfect match is found in the relevant spectral range. It is found that nonlocal effects in graphene's conductivity become relevant for the emission rate for small Fermi energies and small distances between the dipole and the graphene sheet.B.A.F. and N.M.R.P. acknowledge support from the European Commission through the project "Graphene-Driven Revolutions in ICT and Beyond" (Ref. No. 785219), and the Portuguese Foundation for Science and Technology (FCT) in the framework of the Strategic Financing UID/FIS/04650/2013. Additionally, N.M.R.P. acknowledges COMPETE2020, PORTUGAL2020, FEDER, and the Portuguese Foundation for Science and Technology (FCT) through Projects No. PTDC/FIS-NAN/3668/2013 and No. POCI-01-0145-FEDER-028114. B.A. acknowledges the hospitality of CeFEMA, where he was a visiting researcher during part of the time in which this work was developed, and financial support from Portuguese Foundation for Science and Technology (FCT) through Project No. CEECIND/02936/2017

Anthocyanin-rich extract of jabuticaba epicarp as a natural colorant: Optimization of heat- and ultrasound-assisted extractions and application in a bakery product

Heat- and ultrasound-assisted extractions of anthocyanins from jabuticaba epicarp were optimized and the colouring potential of the developed extract was tested on macarons. The independent variables time (t), solvent concentration (S), and temperature (T) or power (P) were combined in a five-level central composite design coupled with response surface methodology. The delphinidin-3-O-glucoside and cyanidin-3-O-glucoside levels monitored by HPLC-DAD-ESI/MS were used as response criteria. The developed models were successfully fitted to the experimental data and used to determine optimal extraction conditions. HAE was the most efficient method yielding 81 ± 2 mg/g extract under optimal conditions (t = 21.8 min, T = 47.1 °C and S = 9.1% ethanol, v/v). Macarons were then produced using the optimized anthocyanin-rich colouring extract and their colour parameters and nutritional profile were monitored during shelf-life. The obtained results provided useful information for the development of anthocyanin-rich extracts from a bio-waste with potential use as natural food colorants.info:eu-repo/semantics/publishedVersio

Phenolic compounds: current industrial applications, limitations and future challenges

Phenolic compounds are natural bioactive molecules found mainly in plant tissues that have shown interesting bioactivities, such as antioxidant, antimicrobial, anti-inflammatory, and antiproliferative activities, among others, which has led to great interest in their use by several industries. However, despite the large number of scientific studies on this topic, some issues still need to be studied and solved, such as the understanding of the main actions of these compounds in organisms. Besides their large potential applicability in industry, phenolic compounds still face some issues making it necessary to develop strategies to improve bioavailability, sustainable technologies of extraction and refinement, and stability procedures to increase the range of applicability. This review focuses on the most recent advances in the applications of phenolic compounds in different technological and medicinal areas. In addition, techniques to improve their sustainable resourcing, stability and bioavailability will be presented and discussed. This journal isFoundation for Science and Technology (FCT, Portugal) is acknowledged for financial support by national funds FCT/ MCTES to CIMO (UIDB/00690/2020). National funding by FCT, P. I., through the institutional scientific employment programcontract for Lillian Barros contract and through the individual scientific employment program-contract for Sandrina A. Heleno, and B. Albuquerque Research grant (SFRH/BD/136370/2018 ). European Regional Development Fund (ERDF) through the Regional Operational Program North 2020, within the scope of Project NORTE-01-0145-FEDER-023289: DeCodE and project Mobilizador Norte-01-0247-FEDER-024479: ValorNatural®. FEDER-Interreg España-Portugal programme is acknowledged for financial support through the project 0377_Iberphenol_6_E.info:eu-repo/semantics/publishedVersio

Chemical characterization and antioxidant proprieties of Myrciaria jaboticaba bioresidues

Jabuticaba (Myrciaria jaboticaba (Vall.) O. Berg) is a Brazilian berry very appreciated for in natura consumption. However, its epicarp is not normally consumed, and in manufacture of products from jabuticaba fruit, it is responsible for the generation of large amounts of residues [1,2]. The exploration of by-products is becoming important for the obtainment of valuable bioactive compounds for food and pharmaceutical industries [2]. In this context, the present work aimed in the characterization of the main bioactive compounds present in jabuticaba epicarps and its potential antioxidant.Foundation for Science and Technology (FCT, Portugal) for financial support by national funds FCT/MCTES to CIMO (UIDB/00690/2020); national funding by FCT, P.I., through the institutional scientific employment program-contract for M.I. Dias, L. Barros, and C. Pereira contract; and B. Albuquerque (SFRH/BD/136370/2018) PhD grant; ERDF through the Regional Operational Program North 2020, within the scope of Project NORTE-01-0145-FEDER-023289: DeCodE and project Mobilizador Norte-01-0247-FEDER-024479: ValorNatural®; FEDER-Interreg España-Portugal programme for financial support through the project 0377_Iberphenol_6_E.info:eu-repo/semantics/publishedVersio

Teores de óleo e proteína em grãos de soja, com diferentes manejos de percevejo, da colheita ao armazenamento, utilizando a espectroscopia no infravermelho próximo (NIR).

ABSTRACT: The aim was to determine changes in oil and protein content in soybean grain after different stink bugs field managements, on harvest and after of grain storage, using near infrared spectroscopy (NIR). Three stink bugs control managements were used in the soybean crop season as: 1-soybean producer management area; 2-standard integrated pest management area; 3-control management area (no pesticides applied). After harvest and at 3, 6, 9 and 12 months after storage time, samples of grain were taken to analyze oil and protein content at NIR. The experiment was maintained in a room at 25° C and 60% of relative humidity during one year of storage time. The results showed an increase in protein and a decrease in lipid content during storage. The increase of stink bug attack in the field caused an increase in the protein content during storage, however no changes in lipid content occurred. RESUMO: O objetivo do trabalho foi verificar variação nos teores de óleo e proteína em grãos de soja, com diferentes manejos de percevejo, no momento da colheita e após determinado período de armazenamento, utilizando o NIR. Os tratamentos pesquisados neste estudo foram amostras de grãos de várias lavouras de soja e três condições de tratamentos: 1-área do produtor, 2-área com o MIP e 3-área testemunha. O experimento foi conduzido em BODs, sendo as avaliações no ponto zero (colheita), aos três, seis, nove e doze meses de armazenamento. Em condições ideais de armazenamento (25ºC e umidade relativa de 60%), ocorreu um aumento nos teores de proteína e uma diminuição nos teores de lipídios dos grãos de soja ao longo do armazenamento. O aumento de ataque de percevejos ocasionou aumento nos teores de proteína dos grãos de soja durante o armazenamento, entretanto sem alterar os teores de lipídios dos grãos

Plant phenolic extracts as an effective strategy to control Staphylococcus aureus, the dairy industry pathogen

Staphylococcus aureus is one of the most common contagious mastitis pathogens. Bovine mastitis is considered an important reservoir for dairy industry contamination, and therefore to ensure S. aureus control has gained a pivotal importance. Natural matrices present multiple biological effects, being its antimicrobial potential increasingly reported. Thus, the present study aims to assess the antibacterial activity of several methanol:water extracts, obtained from plants, against Staphylococcus aureus. Moreover, the most effective extract was characterized in terms of phenolic compounds, by using high performance liquid chromatography coupled to diode array and mass spectrometer detectors. Among the tested extracts, Eucalyptus globulus was the most effective against all tested S. aureus strains, followed by Juglans regia and Foeniculum vulgare. Inhibition halos of the plant extracts varied between 8.0-16.0 mm, excepting for F. vulgare in which two evident halos were observed: one with growth inhibition (5.0-7.0 mm) and a second one with visible cell density reduction (13.0-14.0 mm). Susceptibility assays evidenced that E. globulus extract exerted the highest antibacterial activity (MICs=0.195-0.39 mg/mL), being effective against all the tested strains. Among the phenolic compounds identified in this extract, gallotannins, ellagic acid glycoside, and quercetin derivatives, were the most abundant; and therefore, may exert a positive and contributive effect to the observed antibacterial effect. Overall, the use of plant extracts to control bovine mastitis caused by S. aureus is a promising solution that could contribute to the reduction of the occurrence of dairy food industry contaminations, providing considerable benefits to agro-industries on the formulation of high-quality and safety dairy products.This study was supported by the Portuguese Foundation for Science and Technology (FCT) (grant number SFRH/BPD/84488/2012) under the scope of the strategic funding of UID/BIO/04469/2013 unit and COMPETE 2020 (POCI-01-0145-FEDER-006684) and BioTecNorte operation (NORTE-01-0145-FEDER-000004) funded by European Regional Development Fund under the scope of Norte2020 − Programa Operacional Regional do Norte, as also Pest-OE/AGR/UI0690/2013 to CIMO. The authors are also grateful to the Interreg España-Portugal for financial support through the project 0377_Iberphenol_6_E and to Ana Maria Carvalho for the collection and identification of the wild samples, chemically characterized in previous studies.info:eu-repo/semantics/publishedVersio

Bio-based nanoparticles as a carrier of β-carotene: production, characterisation and in vitro gastrointestinal digestion

β-carotene loaded bio-based nanoparticles (NPs) were produced by the solvent-displacement method using two polymers: zein and ethylcellulose. The production of NPs was optimised through an experimental design and characterised in terms of average size and polydispersity index. The processing conditions that allowed to obtain NPs (<100 nm) were used for β-carotene encapsulation. Then β-carotene loaded NPs were characterised in terms of zeta potential and encapsulation efficiency. Transmission electron microscopy, Fourier transform infrared spectroscopy and X-ray diffraction analysis were performed for further morphological and chemical characterisation. In the end, a static in vitro digestion following the INFOGEST protocol was performed and the bioaccessibility of β-carotene encapsulated in both NPs was determined. Results show that the best conditions for a size-controlled production with a narrow size distribution are lower polymer concentrations and higher antisolvent concentrations. The encapsulation of β-carotene in ethylcellulose NPs resulted in nanoparticles with a mean average size of 60 ± 9 nm and encapsulation efficiency of 74 ± 2%. β-carotene loaded zein-based NPs resulted in a mean size of 83 ± 8 nm and encapsulation efficiency of 93 ± 4%. Results obtained from the in vitro digestion showed that β-carotene bioaccessibility when encapsulated in zein NPs is 37 ± 1%, which is higher than the value of 8.3 ± 0.1% obtained for the ethylcellulose NPs.This research was funded by “MobFood—Mobilizing scientific and technological knowledge in response to the challenges of the agri-food market” (POCI-01-0247-FEDER-024524; LISBOA-01-0247-FEDER024524), by “MobFood” Consortium, and financed by European Regional Development Fund (ERDF), through the Incentive System to Research and Technological development, within the Portugal2020 Competitiveness and Internationalization Operational Program. The research also received funding from the European Union’s H2020 research and innovation programme under the Marie Sklodowska-Curie grant agreement N 778388 (H2020MSCA-RISE-2017 project Food for Diabetes and Cognition (FODIAC), and grant agreement N 713640 (MSCA2015-COFUND-FP), and MICRODIGEST project (grant agreement 037716) co-funded by FCT and ERDF through COMPETE2020.info:eu-repo/semantics/publishedVersio

Are coffee silverskin extracts safe for topical use? An in vitro and in vivo approach

Recent changes in regulatory requirements and social views on animal testing have incremented the development of reliable alternative tests for predicting skin and ocular irritation potential of products based on new raw materials. In this regard, botanical ingredients used in cosmetic products are among those materials, and should be carefully reviewed concerning the potential presence of irritant constituents. In particular, cosmetic products used on the face, in vicinity of the eyes or that may come in contact with mucous membranes, should avoid botanical ingredients that contain, or are suspected to contain, such ingredients. In this study, we aimed to evaluate the effect of a new cosmetic ingredient, namely, coffee silverskin (CS), with an in vitro skin and ocular irritation assay using reconstructed human epidermis, EpiSkin™, and human corneal epithelial model, SkinEthics™ HCE, and an in vivo assay. Three different extracts of CS were evaluated. The histology of the models after extracts applications was analysed. The in vitro results demonstrated that extracts were not classified as irritant and the histological analyses proved that extracts did not affect both models structure. The content of caffeine, 5-hydroxymethyl furfural and chlorogenic acid was quantified after the epidermal assay. The in vivo test carried out with the most promising extract (hydroalcoholic) showed that, with respect to irritant effects, these extracts can be regarded as safe for topical application