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Wavelength Division Multiplexing, WDM, is a technology developed for applications in telecommunications with the purpose of combining numerous wavelength signals into one single fibre. The aim of this research is the characterization of WDM systems of ring resonators with planar optical waveguides. The optical responses for different configurations, dimensions, and materials are analysed by doing a parametric study both considering analytical expressions and a Finite Element Tool. The results are from add-drop topologies with one, two and three rings. The main difference between topologies with the same parameters is the number of resonance wavelengths, which is higher due to the increase in the number of ring-shaped waveguides. It is concluded that adjusting the rings’ dimensions, the resonant wavelengths are tuned. Furthermore, the higher the rings’ radius the lower is the free spectral range, that can take values from 40 nm to 90 nm. Then, the number of resonant peaks in a wavelength range may change. Also, 1500–5000 describes the values computed for the quality factor, whereas the full width at half maximum varies within some units of nanometres. For models with different core materials, the higher transmittances decrease with lower core refractive indexes and the resonance width increases. These are new degrees of freedom to tune the response of the device that can definitely work as optical wavelength multiplexer, having losses from 20% to 40% considering the transmitted optical power.

New phenomena have been discovered at the nanoscale that allow us to manipulate light and design devices. Evanescent waves such as Surface Plasmon Polaritons are excited in dielectric–metal interfaces and propagate in the metal. If they reach other interfaces, they may be transmitted by the metal. It is a phenomenon known as Extraordinary Optical Transmission that occurs in nanostructures at the optical range. Depending on the metal it is possible to tune the wavelengths and incident angles where this phenomenon occurs. Gold, silver, aluminium and copper nanolayers are analysed on top of silicon (a-Si and c-Si) considering a sweep between 250 nm and 2500 nm. Considering a novel model based on Fresnel Coefficients in absorbing media, it is possible to improve energy harvesting in the ultraviolet–visible range, mainly due to the propagation of Surface Plasmon Polaritons. Then, the role of Surface Plasmon Polaritons in Air–Metal–Silicon nanostructures is analysed. The inclusion of the metal layer may decrease the reflectance by at least 10%, reaching values higher than 60%. The presented charts allow us to analyse the materials, wavelengths and incident angles where reflectance is decreased. There, the inclusion of metal layers brings benefits to the photodetection, since more energy is available in the absorbing layer. Considering this approach, the detection of specific wavelengths may be improved by introducing metals in the detectors.

In this article, a plasmonic gold nanoantenna is proposed as a sensor to monitor refractive index variations between 1.30 and 1.35. These values are defined since they are characteristic of, for instance, water-based solutions, DNA, or haemoglobin. To simulate the device a novel model is used, which takes advantage of the wave-particle dualism and the generalised Fresnel coefficients for absorbing media. Although it is a time-domain model, in this research work the model is improved to compute steady state and frequency-domain results. The response to a Dirac excitation is obtained using that novel model. The steady state is reached for a long pulse emission. The long pulse emission is emulated by a Dirac comb and consequently, the optical response of the device for this kind of excitation is obtained considering the sum of several Dirac's responses shifted in time. Then, steady state might be reached as suggested by the presented results. Taking into account the obtained pulse responses, the refractive index sensor for the range 1.30–1.35 is proposed. The obtained results suggest that 350 nm and 450 nm are the best wavelengths to detect these analyte variations. The sensitivity reaches values up to around 110%/RIU, but sensitivities around 80%/RIU are computed within the range 250–500 nm.

Rodrigo Vilares-Morgado,1,2 Vera Correia,3 Ana Margarida Ferreira,1 Flávio Alves,1 António Benevides Melo,1,3 Sérgio Estrela-Silva,1,3 Joana Araújo,1,3 João Tavares-Ferreira,1,3 Marta Silva,1 Amândio Rocha-Sousa,1,2 Angela Carneiro,1,2 João Barbosa-Breda1,2,4 1Department of Ophthalmology, Centro Hospitalar e Universitário de São João, Porto, Portugal; 2UnIC@RISE, Department of Surgery and Physiology, Faculty of Medicine of the University of Porto, Porto, Portugal; 3Faculty of Medicine, University of Porto, Porto, Portugal; 4KULeuven, Research Group Ophthalmology, Department of Neurosciences, Leuven, BelgiumCorrespondence: Rodrigo Vilares-Morgado, Department of Ophthalmology, Centro Hospitalar e Universitário de São João, Alameda Professor Hernâni Monteiro, 4202 – 451, Porto, Portugal, Tel +351 914 471 067, Fax +351 225 512 100, Email vilaresmorgador@gmail.comPurpose: To evaluate whether repeated intravitreal injections (IVI) with an anti-vascular endothelial growth factor (anti-VEGF) agent are associated with glaucomatous progression in eyes with glaucoma spectrum diseases (GSD).Methods: Single-center, retrospective, longitudinal study of patients with bilateral and similar GSD who: (1) received ≥ 8 IVI in only one eye during the study period; (2) had ≥ 2 retinal nerve fiber layer thickness (RNFL) measurements obtained by spectral-domain optical coherence tomography (SD-OCT) at least 12 months apart. The primary outcome was the absolute RNFL thickness change, comparing injected and fellow uninjected eyes. Linear mixed effects models were constructed, including a multivariable model.Results: Sixty-eight eyes from 34 patients were included, 34 injected and 34 fellow uninjected eyes. Average baseline age was 67.68± 21.77 years with a follow-up of 3.66± 1.89 years and 25.12± 14.49 IVI. RNFL thickness decreased significantly from 80.92± 15.78 to 77.20± 17.35 μm (p< 0.001; − 1.18± 1.93 μm/year) in injected eyes and from 79.95± 17.91 to 76.61± 17.97 μm (p< 0.001; − 1.07± 0.98 μm/year) in uninjected eyes. In a multivariable linear mixed model of injected eyes, only higher baseline RNFL thickness (p < 0.001) significantly predicted higher absolute RNFL thickness loss. Neither absolute RNFL thickness variation (p=0.716) nor RNFL rate (p=0.779) was significantly different between paired injected and uninjected eyes. Absolute IOP variation was not significantly different between groups (16.62± 4.77 to 15.09± 4.34 mmHg in injected eyes and 17.68± 5.01 to 14.50± 3.39 mmHg in fellow uninjected eyes; p=0.248). The proportion of eyes receiving glaucoma medical treatment increased significantly in both groups (55.9% to 76.5% in injected eyes; p=0.039; 58.8% to 76.5% in uninjected eyes; p = 0.031). The number of glaucoma medications also increased significantly in both groups (1.03± 1.11 to 1.59± 1.18 glaucoma medications in injected eyes; p=0.003; 1.09± 1.11 to 1.56± 1.19 glaucoma medications in uninjected eyes; p=0.003).Conclusion: Repeated IVI do not seem to accelerate glaucomatous progression. Future studies with a longer follow-up are needed.Keywords: glaucoma, intravitreal injections, progression, optical coherence tomography, retinal nerve fiber layer thickness

Abstract Renewable energies are increasingly playing an important role in the world’s energy supply. Society demands new solutions to solve environmental issues caused by fossil fuels. The importance of photovoltaic technology has been increasing and consequently, the necessity to have more accurate models to characterise the performance of solar cells during their entire lifetime has rose as well. Performance problems may appear during devices’ lifetimes associated with factors, such as weather conditions or faulty installation. Cracking might occur, leading to abrupt reductions on the produced power, quite difficult and expensive to fix. The I–V curves of a defected or cracked solar cell might not have the shape imposed by the usual models as 1M5P. In this article, cracked c-Si solar cells are modelled using a novel model: d1MxP. This model is based on the discretisation of the diode’s response on models as 1M5P. Instead of imposing a shape and compute some parameters to fit it on experimental data, the proposed model connects every two points. The results suggest a better fit using the proposed model in comparison with the 1M5P, not only in the original curves, but also modelling cracked cells. As consequence of a better fitting, the computation of important figures of merit as maximum power point or fill factor, reveals to be more precise. It is concluded that the proposed model might characterise the performance of a solar cell, even cracked, which is a huge advance aiming the possibility of simulating complex problems during the cells’ operation lifetime.

Nowadays, optical systems play an important role in communications. Dual depletion PIN photodiodes are common devices that can operate in different optical bands, depending on the chosen semiconductors. However, since semiconductor properties vary with the surrounding conditions, some optical devices/systems can act as sensors. In this research work, a numerical model is implemented to analyze the frequency response of this kind of structure. It considers both transit time and capacitive effects, and can be applied to compute photodiode frequency response under nonuniform illumination. The InP-In0.53Ga0.47As photodiode is usually used to convert optical into electrical power at wavelengths around 1300 nm (O-band). This model is implemented considering an input frequency variation of up to 100 GHz. The focus of this research work was essentially the determination of the device’s bandwidth from the computed spectra. This was performed at three different temperatures: 275 K, 300 K, and 325 K. The aim of this research work was to analyze if a InP-In0.53Ga0.47As photodiode can act as a temperature sensor, to detect temperature variations. Furthermore, the device dimensions were optimized, to obtain a temperature sensor. The optimized device, for a 6 V applied voltage and an active area of 500 μm2, had a total length of 2.536 μm, in which 53.95% corresponded to the absorption region. In these conditions, if the temperature increases 25 K from the room temperature, one should expect a bandwidth increase of 8.374 GHz, and if it decreases 25 K from that reference, the bandwidth should reduce by 3.620 GHz. This temperature sensor could be incorporated in common InP photonic integrated circuits, which are commonly used in telecommunications.

Solar cell equivalent circuit modelling is usually based on continuous I-V models, with a set of data obtained by analytical expressions. This work proposes an almost discrete novel mathematical method and correspondent electrical model, based on the I-V curve adjustment at every two adjacent points. It is based on the discretisation of any diode model behaviour, such as the 1M5P (also known as 1D5P) or the 1M7P (also known as 2D7P). For this reason, the model is named d1MxP, meaning that it is a discrete (d) model (1M) with x parameters (xP). The modelling methodology validation process uses experimental data already published in the literature. According to the presented results, the proposed method shows increased accuracy when compared to the 1M5P or 1M7P equivalent models. The accuracy on the maximum power point and fill factor determination is relevant, resulting in an improvement of up to 3.34% in the maximum power, up to 5.70% in its voltage and up to 8.20% in its current, for the analysed data. Furthermore, Fill Factor values, have variation from up to 35.98%. The temperature influence on the silicon solar cell is also analysed, to validate the results. The proposed method allows highly accurate curve fitting to the (experimental) points and consequently, to obtain a more accurate model to analyse the performance of solar cells under different conditions.

Renewable energy sources are becoming more and more essential to energy production as societies evolve toward a fossil-fuel-free world. Solar energy is one of the most abundant sources of green energy. Nanoantennas can be used to improve and enhance the absorption of light into a photovoltaic cell in order to generate more current. In this study, different nanoantenna structures are analysed in tandem with a silicon solar cell in an effort to improve its output. The nanoantennas studied are metallic aperture nanoantennas made up of either silver, aluminium, gold or copper. The three geometries compared are rectangular, circular and triangular. The maximum field enhancement obtained is for an aluminium rectangular nanoantenna of 50 nm thickness. Despite this, the geometry with more improvements compared with a basic silicon cell was the circle geometry with a 100 nm radius.

Suicidal thoughts and behaviors among juvenile justice populations are elevated. However, the characteristics of justice-involved youth who consider and attempt suicide are not well understood. This study examined suicidal ideation and attempt with first-time, preadjudicated diverted youth, and the relationship with commonly associated risk factors. The sample included 135 youth (50% male, M age = 14.48) that provided complete responses to self-reported lifetime suicidal ideation and attempt items. Analyses examined relationships between suicidal ideation/attempt and mental health, child welfare involvement, delinquency, self-cutting, and substance use. First time, preadjudicated diverted youth reported high rates of lifetime suicidal ideation (27%) and attempt (17%). Suicidal ideation and attempt were associated with sexually minoritized status and self-cutting, while child welfare involvement was only associated with suicidal ideation. This high-risk population would benefit from refined suicide screening and prevention services not always available to justice-involved youth living in the community., Competing Interests: We have no conflict of interest to disclose.

The development of effective antiviral drugs against SARS-CoV-2 is urgently needed and a global health priority. In light of the initial data regarding the repurposing of hydroxychloroquine (HCQ) to tackle this coronavirus, herein we present a quantitative synthesis and spectroscopic and thermal characterization of seven HCQ room temperature ionic liquids (HCQ-ILs) obtained by direct protonation of the base with two equivalents of organic sulfonic, sulfuric and carboxylic acids of different polarities. Two non-toxic and hydrophilic HCQ-ILs, in particular, [HCQH2][C1SO3]2 and [HCQH2][GlcCOO]2, decreased the virus-induced cytopathic effect by two-fold in comparison with the original drug, [HCQH2][SO4]. Despite there being no significant differences in viral RNA production between the three compounds, progeny virus production was significantly affected (p < 0.05) by [HCQH2][GlcCOO]2. Overall, the data suggest that the in vitro antiviral activities of the HCQ-ILs are most likely the result of specific intra- and intermolecular interactions and not so much related with their hydrophilic or lipophilic character. This work paves the way for the development of future novel ionic formulations of hydroxychloroquine with enhanced physicochemical properties.

Influenza NS1 is a promising anti-influenza target, considering its conserved and druggable structure, and key function in influenza replication and pathogenesis. Notwithstanding, target identification and validation, strengthened by experimental data, are lacking. Here, we further explored our previously designed structure-based antiviral rationale directed to highly conserved druggable NS1 regions across a broad spectrum of influenza A viruses. We aimed to identify NS1-mutated viruses exhibiting a reduced growth phenotype and/or an altered cell apoptosis profile. We found that NS1 mutations Y171A, K175A (consensus druggable pocket 1), W102A (consensus druggable pocket 3), Q121A and G184P (multiple consensus druggable pockets) - located at hot spots amenable for pharmacological modulation - significantly impaired A(H1N1)pdm09 virus replication, in vitro. This is the first time that NS1-K175A, -W102A, and -Q121A mutations are characterized. Our map-and-mutate strategy provides the basis to establish the NS1 as a promising target using a rationale with a higher resilience to resistance development., (Copyright © 2021 Elsevier Inc. All rights reserved.)

Common bean is a nutritious food legume widely appreciated by consumers worldwide. It is a staple food in Latin America, and a component of the Mediterranean diet, being an affordable source of protein with high potential as a gourmet food. Breeding for nutritional quality, including both macro and micronutrients, and meeting organoleptic consumers' preferences is a difficult task which is facilitated by uncovering the genetic basis of related traits. This study explored the diversity of 106 Portuguese common bean accessions, under two contrasting environments, to gain insight into the genetic basis of nutritional composition (ash, carbohydrates, fat, fiber, moisture, protein, and resistant starch contents) and protein quality (amino acid contents and trypsin inhibitor activity) traits through a genome-wide association study. Single-nucleotide polymorphism-trait associations were tested using linear mixed models accounting for the accessions' genetic relatedness. Mapping resolution to the gene level was achieved in 56% of the cases, with 102 candidate genes proposed for 136 genomic regions associated with trait variation. Only one marker-trait association was stable across environments, highlighting the associations' environment-specific nature and the importance of genotype × environment interaction for crops' local adaptation and quality. This study provides novel information to better understand the molecular mechanisms regulating the nutritional quality in common bean and promising molecular tools to aid future breeding efforts to answer consumers' concerns.