Electrically charged regular black holes in nonlinear electrodynamics: light rings, shadows, and gravitational lensing

Within nonlinear electrodynamics (NED), photons follow null geodesics of an effective geometry, which is different from the geometry of the spacetime itself. Over the last years, several works were dedicated to investigate the motion of photons in the effective geometry of NED-based magnetically charged regular black hole (RBH) solutions. However, there are few works considering electrically charged RBHs. We study the light rings, shadows, and gravitational lensing of the electrically charged RBH solution proposed by Irina Dymnikova (ID), which is a static and spherically symmetric spacetime with a NED source. We show that the shadow associated to the effective geometry can be almost 10% bigger that the one associated to the standard geometry. We also find that the ID solution may mimic the shadow properties of the Reissner-Nordstrom (RN) BH, for low- ¨ to-extreme values of the electric charge. Besides that, by using the backwards ray-tracing technique, we obtain that ID and RN BH solutions can have a very similar gravitational lensing, for some values of the correspondent electric charges. We also show that the motion of photons in the effective geometry can be interpreted as a non-geodesic curve submitted to a 4-force term, from the perspective of an observer in the standard geometry.publishe

Mitogen-activated protein kinase kinase 5 regulates proliferation and biosynthetic processes in procyclic forms of Trypanosoma brucei

The pathogenic protozoan T. brucei alternates into distinct developmental stages in the mammalian and insect hosts. The mitogen-activated protein kinase (MAPK) signaling pathways transduce extracellular stimuli into a range of cellular responses, which ultimately lead to the adaptation to the external environment. Here, we combined a loss of function approach with stable isotope labeling with amino acids in cell culture (SILAC)-based mass spectrometry (MS) to investigate the role of the mitogen-activated protein kinase kinase 5 (MKK5) in T. brucei. The silencing of MKK5 significantly decreased the proliferation of procyclic forms of T. brucei. To shed light on the molecular alterations associated with this phenotype, we measured the total proteome and phosphoproteome of cells silenced for MKK5. In the total proteome, we observed a general decrease in proteins related to ribosome and translation as well as down-regulation of several components of the fatty acids biosynthesis pathway. In addition, we observed alterations in the protein levels and phosphorylation of key metabolic enzymes, which point toward a suppression of the oxidative metabolism. Taken together, our findings show that the silencing of MKK5 alters cell growth, energy metabolism, protein and fatty acids biosynthesis in procyclic T. brucei

Bond behavior between glulam and GFRP's by pullout tests

To evaluate the bond behavior between glulam and GFRP rods, applied according to the near-surface mounted strengthening technique, an experimental program composed of beam and direct pullout tests was carried. In this experimental program three main variables were analyzed: the GFRP type, the GFRP location into the groove, and the bond length. From the monitoring system it was registered the loaded and free end slips, and the pullout force. Based on these experimental results, and applying an analytical-numerical strategy, the local bond stress-slip relationship was calculated. In this work the tests are described, the obtained results are presented and discussed, and the applicability of the inverse analysis to obtain the local bond law is demonstrated.This work is supported by FEDER funds through the Operational Programme for Competitiveness Factors - COMPETE and National Funds through FCT – Portuguese Foundation for Science and Technology under the project PTDC/ECM/74337/2006. The authors also like to thank all the companies that have been involved supporting and contributing for the development of this study, mainly: INEGI, S&P Clever Reinforcement Ibérica Lda., Portilame, MAPEI and Rothoblaas

Optoelectronic simulations for novel light management concepts in Cu(In,Ga)Se2 solar cells

One of the trends making its way through the Photovoltaics (PV) industry, is the search for new application possibilities. Cu(In,Ga)Se2 (CIGS) thin film solar cells stand out due to their class leading power conversion efficiency of 23.35 %, flexibility, and low cost. The use of sub-μm ultrathin CIGS solar cells has been gaining prevalence, due to the reduction in material consumption and the manufacturing time. Precise CIGS finite-difference time-domain (FDTD) and 3D-drift diffusion baseline models were developed for the Lumerical suite and a 1D electrical model for SCAPS, allowing for an accurate description of the optoelectronic behavior and response of thin and ultrathin CIGS solar cells. As a result, it was possible to obtain accurate descriptions of the optoelectronic behavior of thin and ultrathin solar cells, and to perform an optical study and optimization of novel light management approaches, such as, random texturization, photonic nanostructures, plasmonic nanoparticles, among others. The developed light management architectures enabled to push the optical performance of an ultrathin solar cell and even surpass the performance of a thin film solar cell, enabling a short-circuit current enhancement of 6.15 mA/cm2 over an ultrathin reference device, without any light management integrated.publishe

A wastewater-based epidemiology tool for COVID-19 surveillance in Portugal

Funding: Strategic funding of Fundação para a Ciência e a Tecnologia (FCT), Portugal, to cE3c and BioISI Research Units ( UIDB/00329/2020 and UIDB/04046/2020 ] is also gratefully acknowledged. This work was supported by Programa Operacional de Competitividade e Internacionalização (POCI) (FEDER component), Programa Operacional Regional de Lisboa , and Programa Operacional Regional do Norte (Project COVIDETECT, ref. 048467 ).The presence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in wastewater produced interest in its use for sentinel surveillance at a community level and as a complementary approach to syndromic surveillance. With this work, we set the foundations for wastewater-based epidemiology (WBE) in Portugal by monitoring the trends of SARS-CoV-2 RNA circulation in the community, on a nationwide perspective during different epidemiological phases of the pandemic. The Charité assays (E_Sarbecco, RdRP, and N_Sarbecco) were applied to monitor, over 32-weeks (April to December 2020), the dynamics of SARS-CoV-2 RNA at the inlet of five wastewater treatment plants (WWTP), which together serve more than two million people in Portugal. Raw wastewater from three Coronavirus disease 2019 (COVID-19) reference hospitals was also analyzed during this period. In total, more than 600 samples were tested. For the first weeks, detection of SARS-CoV-2 RNA was sporadic, with concentrations varying from 103 to 105 genome copies per liter (GC/L). Prevalence of SARS-CoV-2 RNA increased steeply by the end of May into late June, mainly in Lisboa e Vale do Tejo region (LVT), during the reopening phase. After the summer, with the reopening of schools in mid-September and return to partial face-to-face work, a pronounced increase of SARS-CoV-2 RNA in wastewater was detected. In the LVT area, SARS-CoV-2 RNA load agreed with reported trends in hotspots of infection. Synchrony between trends of SARS-CoV-2 RNA in raw wastewater and daily new COVID-19 cases highlights the value of WBE as a surveillance tool, particularly after the phasing out of the epidemiological curve and when hotspots of disease re-emerge in the population which might be difficult to spot based solely on syndromic surveillance and contact tracing. This is the first study crossing several epidemiological stages highlighting the long-term use of WBE for SARS-CoV-2.PostprintPeer reviewe

On the importance of joint mitigation strategies for front, bulk, and rear recombination in ultrathin Cu(In,Ga)Se2 solar cells

Several optoelectronic issues, such as poor optical absorption and recombination limit the power conversion efficiency of ultrathin Cu(In,Ga)Se2 (CIGS) solar cells. To mitigate recombination losses, two combined strategies were implemented: a Potassium Fluoride (KF) Post-Deposition Treatment (PDT) and a rear interface passivation strategy based on an Aluminium Oxide (Al2O3) point contact structure. The simultaneous implementation of both strategies is reported for the first time on ultrathin CIGS devices. Electrical measurements and 1-D simulations demonstrate that, in specific conditions, devices with only KF-PDT may outperform rear interface passivated based devices. By combining KF-PDT and rear interface passivation, an enhancement in open-circuit voltage of 178 mV is reached over devices that have a rear passivation only and of 85 mV over devices with only a KF-PDT process. Time-Resolved Photoluminescence measurements showed the beneficial effects of combining KF-PDT and the rear interface passivation at decreasing recombination losses in the studied devices, enhancing charge carrier lifetime. X-ray photoelectron spectroscopy measurements indicate the presence of a In and Se rich layer that we linked to be a KInSe2 layer. Our results suggest that when bulk and front interface recombination values are very high, they dominate and individual passivation strategies work poorly. Hence, this work shows that for ultrathin devices, passivation mitigation strategies need to be implemented in tandem.publishe

On the importance of joint mitigation strategies for front, bulk, and rear recombination in ultrathin Cu(In,Ga)Se2 solar cells

Several optoelectronic issues, such as poor optical absorption and recombination limit the power conversion efficiency of ultrathin Cu(In,Ga)Se2 (CIGS) solar cells. To mitigate recombination losses, two combined strategies were implemented: a Potassium Fluoride (KF) Post-Deposition Treatment (PDT) and a rear interface passivation strategy based on an Aluminium Oxide (Al2O3) point contact structure. The simultaneous implementation of both strategies is reported for the first time on ultrathin CIGS devices. Electrical measurements and 1-D simulations demonstrate that, in specific conditions, devices with only KF-PDT may outperform rear interface passivated based devices. By combining KF-PDT and rear interface passivation, an enhancement in open-circuit voltage of 178 mV is reached over devices that have a rear passivation only and of 85 mV over devices with only a KF-PDT process. Time-Resolved Photoluminescence measurements showed the beneficial effects of combining KF-PDT and the rear interface passivation at decreasing recombination losses in the studied devices, enhancing charge carrier lifetime. X-ray photoelectron spectroscopy measurements indicate the presence of a In and Se rich layer that we linked to be a KInSe2 layer. Our results suggest that when bulk and front interface recombination values are very high, they dominate and individual passivation strategies work poorly. Hence, this work shows that for ultrathin devices, passivation mitigation strategies need to be implemented in tandem.publishe

Encapsulation of Nanostructures in a Dielectric Matrix Providing Optical Enhancement in Ultrathin Solar Cells

The incorporation of nanostructures in optoelectronic devices for enhancing their optical performance is widely studied. However, several problems related to the processing complexity and the low performance of the nanostructures have hindered such actions in real-life devices. Herein, a novel way of introducing gold nanoparticles in a solar cell structure is proposed in which the nanostructures are encapsulated with a dielectric layer, shielding them from high temperatures and harsh growth processing conditions of the remaining device. Through optical simulations, an enhancement of the effective optical path length of approximately four times the nominal thickness of the absorber layer is verified with the new architecture. Furthermore, the proposed concept in a Cu(In,Ga)Se2 solar cell device is demonstrated, where the short-circuit current density is increased by 17.4%. The novel structure presented in this work is achieved by combining a bottom-up chemical approach of depositing the nanostructures with a top-down photolithographic process, which allows for an electrical contact.This work was funded in part by the Fundação para a Ciência e a Tecnologia (FCT) under Grants IF/00133/2015, PD/BD/142780/2018 and SFRH/BD/ 146776/2019. The authors also want to acknowledge the European Union’s Horizon 2020 Research and Innovation Programme through the ARCIGS-M project under Grant 720887, the Special Research Fund (BOF) of Hasselt University, the FCT through the project NovaCell (PTDC/CTM-CTM/28075/ 2017), and InovSolarCells (PTDC/FISMAC/29696/2017) co-funded by FCT and the ERDF through COMPETE2020. The authors also want to acknowledge Sandra Maya for the production of images used in this work.info:eu-repo/semantics/publishedVersio

Measurement of the quasi-elastic axial vector mass in neutrino-oxygen interactions

The weak nucleon axial-vector form factor for quasi-elastic interactions is determined using neutrino interaction data from the K2K Scintillating Fiber detector in the neutrino beam at KEK. More than 12,000 events are analyzed, of which half are charged-current quasi-elastic interactions nu-mu n to mu- p occurring primarily in oxygen nuclei. We use a relativistic Fermi gas model for oxygen and assume the form factor is approximately a dipole with one parameter, the axial vector mass M_A, and fit to the shape of the distribution of the square of the momentum transfer from the nucleon to the nucleus. Our best fit result for M_A = 1.20 \pm 0.12 GeV. Furthermore, this analysis includes updated vector form factors from recent electron scattering experiments and a discussion of the effects of the nucleon momentum on the shape of the fitted distributions.Comment: 14 pages, 10 figures, 6 table