Interface inductive currents and carrier injection in hybrid perovskite single crystals

nterfaces between the absorbing perovskite and transporting layers are gaining attention as the key locus that governs solar cell operation and long term performance. The interplay of ionic and electronic processes, along with the asymmetrical architecture of any solar cell, makes the interpretation of electrical measurements always inconclusive. A strategy to progress in relating electric responses, operating mechanisms, and device architecture relies upon simplifying the probing structure. Macroscopic CH3NH3PbBr3 single crystals with symmetrical contacts are tested by means of long-time current transient and impedance spectroscopy. It is observed that interfaces govern carrier injection to (and extraction from) perovskite layers through an inductive (negative capacitance) mechanism with a response time in the range of ∼1–1001–100 s under dark conditions and inert atmosphere. Current transient exhibits a slow recovering after the occurrence of an undershoot, signaling a complex carrier dynamics which involves changes in surface state occupancy

Diamond-based electrodes for organic photovoltaic devices

The present paper demonstrates the possibility of replacing indium–tin oxide (ITO) with heavily boron-doped diamond (BDD). Plasma Enhanced Chemically Vapor Deposited BDDs layers of various thicknesses were prepared containing various boron concentrations in a gas phase. The dependence of the above-mentioned parameters on the optical and electrical properties of each BDD was studied in order to achieve optimal conditions for the effective application of diamond electrodes in organic electronics as a replacement for ITO. Bulk-heterojunction polymer–fullerene organic solar cells were fabricated to test the potency of BDD application in photovoltaic devices. The obtained results demonstrated the possibility of the aforementioned application. Even though the efficiency of BDD-based devices is lower compared to those using regular ITO-based architecture, the relevant issues were explained

Benefits of using conductive plastics in shielding configurations to reduce radiated electromagnetic interference

Conductive plastic cabinets have become an alternative to traditional metallic enclosures to shield electronic equipment from electromagnetic interference. These materials allow a wide range of conductivities that can satisfy any particular design. In this paper the benefits of using conductive plastics in enclosure configurations have been evaluated. A design with an outer metallic layer and an inner layer of conductive dielectric can provide advantages from both materials since a conductive plastic box is lighter and its shielding properties may have advantages over metallic materials. An optimum for resonance suppression has been obtained for the hybrid structure. These shielding structures have been evaluated with the help of measurements and simulations. Shielding effectiveness and Q-factor have been used to compare the capabilities of these enclosures with the metallic ones showing their benefits and possibilities. Resonance suppression and shielding levels provided by conductive plastics are discussed.This work was funded by Fundación Séneca, Agencia Regional de Ciencia y Tecnología, through the project 00700/PPC/04 and partly done during a research stay funded by the “Programa de formación y movilidad del personal docente e investigador de la Universidad Politécnica de Cartagena (PMPDI-UPCT-2007)” at the Physical Layer Group, Department of Electronics, University of York

Purification and genetic characterization of gassericin E, a novel co-culture inducible bacteriocin from Lactobacillus gasseri EV1461 isolated from the vagina of a healthy woman

This work was supported by the Spanish Ministry of Economy and Competitiveness (MINECO) through the Project AGL2012-33400 and AGL2013-41980-P, and by the Junta de Andalucía Excellence Project AGR-07345. These projects included FEDER funds. AMB was the recipient of a post-doctoral grant awarded by the Junta de Andalucía as part of the Project AGR-07345.Background: Lactobacillus gasseri is one of the dominant Lactobacillus species in the vaginal ecosystem. Some strains of this species have a high potential for being used as probiotics in order to maintain vaginal homeostasis, since they may confer colonization resistance against pathogens in the vagina by direct inhibition through production of antimicrobial compounds, as bacteriocins. In this work we have studied bacteriocin production of gassericin E (GasE), a novel bacteriocin produced by L. gasseri EV1461, a strain isolated from the vagina of a healthy woman, and whose production was shown to be promoted by the presence of certain specific bacteria in co-culture. Biochemical and genetic characterization of this novel bacteriocin are addressed. Results: We found that the inhibitory spectrum of L. gasseri EV1461 was broad, being directed to species both related and non-related to the producing strain. Interestingly, L. gasseri EV1461 inhibited the grown of pathogens usually associated with bacterial vaginosis (BV). The antimicrobial activity was due to the production of a novel bacteriocin, gassericin E (GasE). Production of this bacteriocin in broth medium only was achieved at high cell densities. At low cell densities, bacteriocin production ceased and only was restored after the addition of a supernatant from a previous bacteriocin-producing EV1461 culture (autoinduction), or through co-cultivation with several other Gram-positive strains (inducing bacteria). DNA sequence of the GasE locus revealed the presence of two putative operons which could be involved in biosynthesis and immunity of this bacteriocin (gaeAXI), and in regulation, transport and processing (gaePKRTC). The gaePKR encodes a putative three-component regulatory system, involving an autoinducer peptide (GaeP), a histidine protein kinase (GaeK) and a response regulator (GaeR), while the gaeTC encodes for an ABC transporter (GaeT) and their accessory protein (GaeC), involved in transport and processing of the bacteriocin. The gaeAXI, encodes for the bacteriocin gassericin E (GasE), a putative peptide bacteriocin (GaeX), and their immunity protein (GaeI). Conclusions: The origin of the strain (vagina of healthy woman) and its ability to produce bacteriocins with inhibitory activity against vaginal pathogens may be an advantage for using L. gasseri EV1461 as a probiotic strain to fight and/or prevent bacterial infections as bacterial vaginosis (BV), since it could be better adapted to live and compete into the vaginal environment.Publisher PDFPeer reviewe

PRIMER REGISTRO DE UNA ABERRACIÓN MARRÓN PARA EL CORMORÁN NEOTROPICAL NANNOPTERUM BRASILIANUM DE MÉXICO

En esta nota, reportamos un caso de aberración del plumaje en el cormorán neotropical Nannopterum brasilianum. Se registró la presencia de un color atípico en el plumaje de un individuo observado en un humedal del norte de México. El ave presentaba una aberración marrón, en la que el color negro original fue sustituido por tonos marrón claro y beige pálido. Observamos el ave alimentándose junto a otros cormoranes con una coloración normal y no mostró comportamientos diferentes. La documentación de fenotipos aberrantes es importante para determinar su frecuencia y patrones geográficos de aparición, especialmente en aves acuáticas con distribuciones geográficas extensas como N. brasilianum. Esta observación representa el primer reporte de aberración de plumaje marrón en esta especie

Huertas orgánicas como solución alimentaria en las veredas ribereñas del rio Guatiquía

Las familias ribereñas del rio Guatiquía han tenido formas tradicionales de cultivar la tierra; sin embargo, hoy deben proveerse en la ciudad de Villavicencio de los alimentos que necesitan porque los terrenos que habitan no son lo suficientemente fértiles perdiendo el interés en la agricultura dejando terrenos improductivos y poniendo en peligro la seguridad alimentaria de la zona. Esta propuesta se orientó buscando una estrategia para el mejoramiento de los suelos de las huertas a partir del proceso de pilotaje, usando cajones de madera también llamados balcanes, con capas de material y abonos orgánicos para el buen desarrollo de las plantas, protegidas con polisombra para evitar las consecuencias de las adversidades climáticas, a través de una labor sustentable; se reunieron miembros de las familias de la zona que conocieron el objetivo del proyecto donde se brindó la oportunidad de trabajar en comunidad para solucionar la necesidad básica de la alimentación. A través de la metodología IAP que recogiendo los saberes y experiencias de los participantes en huertas reciben los diseños de la estrategia de los balcanes como punto de partida y se propone el inicio del trabajo práctico en el espacio proporcionado por una de las familias, se reutilizan maderas para armar las gavetas y se lleva una bitácora de cada uno de los encuentros donde se retroalimenta con todos los participantes los aprendizajes adquiridos durante el proceso preparación, germinación, siembra y desarrollo de las plantas registrando la transformación de la huerta. Se pretende recoger los resultados e identificar los modos de aplicación de la experiencia usando un grupo de discusión a través de un cuestionario guía.The riverside families of the Guatiquía River have had traditional ways of cultivating the land; however, today they must provide themselves in the city of Villavicencio with the food they need because the land they inhabit is not fertile enough, losing interest in agriculture, leaving unproductive land and endangering the food security of the area. This proposal was aimed at seeking a strategy for the improvement of the soils of the orchards from the piloting process, using wooden boxes also called balkans, with layers of material and organic fertilizers for the good development of the plants, protected with polyshade to avoid the consequences of climatic adversities, through sustainable work; members of the families of the area met who knew the objective of the project where the opportunity to work in community to solve the basic need of food was provided. Through the IAP methodology that, collecting the knowledge and experiences of the participants in the gardens, receive the designs of the Balkan strategy as a starting point and the beginning of the practical work is proposed in the space provided by one of the families, they are reused wood to assemble the drawers and a log is kept of each of the meetings where all the participants receive feedback on the learning acquired during the process of preparation, germination, planting and development of the plants, recording the transformation of the garden. It is intended to collect the results and identify the modes of application of the experience using a discussion group through a guide questionnaire

Reversible Formation of Gold Halides in Single‐Crystal Hybrid‐Perovskite/Au Interface upon Biasing and Effect on Electronic Carrier Injection

Solar cells, light emitting diodes, and X‐ray detectors based on perovskite materials often incorporate gold electrodes, either in direct or indirect contact with the perovskite compound. Chemical interactions between active layers and contacts deteriorate the operation and induce degradation, being the identification of the chemical nature of such interfacial structures an open question. Chemical reactivity of gold in contact with the perovskite semiconductor leads to reversible formation of oxidized gold halide species and explains the generation of halide vacancies in the vicinity of the interface. Electrical biasing induces contact reaction and produces modifications of the current level by favoring the ability of perovskite/Au interfaces to inject electronic carriers. The current injection increment does not depend on the halogen source used, either extrinsically by iodine vapor sublimation of Au electrodes, or intrinsically by bias‐driven migration of bromide ions. In addition, the formation of a dipole‐like structure at the reacted electrode that lowers the potential barrier for electronic carriers is confirmed. These findings highlight adequate selection of the external contacts and suggest the need for a deeper understanding of contact reactivity as it dominates the operation characteristics, rather than being governed by the bulk transport properties of the charge carriers, either electronic or ionic

2023 GEIS Guidelines for gastrointestinal stromal tumors

Avapritinib; Gastrointestinal stromal tumor; SurgeryAvapritinib; Tumor estromal gastrointestinal; CirurgiaAvapritinib; Tumor estromal gastrointestinal; CirugíaGastrointestinal stromal tumor (GIST) is the most common malignant neoplasm of mesenchymal origin. GIST spans a wide clinical spectrum that ranges from tumors with essentially no metastatic potential to malignant and life-threatening spread diseases. Gain-of-function mutations in KIT or PDGFRA receptor tyrosine kinases are the crucial drivers of most GISTs, responsible for tumor initiation and evolution throughout the entire course of the disease. The introduction of tyrosine kinase inhibitors targeting these receptors has substantially improved the outcomes in this formerly chemoresistant cancer. As of today, five agents hold regulatory approval for the treatment of GIST: imatinib, sunitinib, regorafenib, ripretinib, and avapritinib. This, in turn, represents a success for a rare neoplasm. During the past two decades, GIST has become a paradigmatic model in cancer for multidisciplinary work, given the disease-specific particularities regarding tumor biology and tumor evolution. Herein, we review currently available evidence for the management of GIST. This clinical practice guideline has been developed by a multidisciplinary expert panel (oncologist, pathologist, surgeon, molecular biologist, radiologist, and representative of patients’ advocacy groups) from the Spanish Group for Sarcoma Research, and it is conceived to provide, from a critical perspective, the standard approach for diagnosis, treatment, and follow-up.This work was supported in part by AECC (CLSEN20004SERR) and the Fero Foundation, both to CS

JANUS: an FPGA-based System for High Performance Scientific Computing

This paper describes JANUS, a modular massively parallel and reconfigurable FPGA-based computing system. Each JANUS module has a computational core and a host. The computational core is a 4x4 array of FPGA-based processing elements with nearest-neighbor data links. Processors are also directly connected to an I/O node attached to the JANUS host, a conventional PC. JANUS is tailored for, but not limited to, the requirements of a class of hard scientific applications characterized by regular code structure, unconventional data manipulation instructions and not too large data-base size. We discuss the architecture of this configurable machine, and focus on its use on Monte Carlo simulations of statistical mechanics. On this class of application JANUS achieves impressive performances: in some cases one JANUS processing element outperfoms high-end PCs by a factor ~ 1000. We also discuss the role of JANUS on other classes of scientific applications.Comment: 11 pages, 6 figures. Improved version, largely rewritten, submitted to Computing in Science & Engineerin

Planetary Nebula Abundances and Morphology: Probing the Chemical Evolution of the Milky Way

This paper presents a homogeneous study of abundances in a sample of 79 northern galactic planetary nebulae whose morphological classes have been uniformly determined. Ionic abundances and plasma diagnostics were derived from selected optical line strengths in the literature, and elemental abundances were estimated with the Ionization Correction Factor developed by Kingsbourgh & Barlow (1994). We compare the elemental abundances to the final yields obtained from stellar evolution models of low-and intermediate-mass stars, and we confirm that most Bipolar planetary nebulae have high nitrogen and helium abundance, and are the likely progeny of stars with main-sequence mass larger than 3 solar masses. We derive =0.27, and discuss the implication of such a high ratio in connection with the solar neon abundance. We determine the galactic gradients of oxygen and neon, and found Delta log (O/H)/Delta R=-0.01 dex/kpc$ and Delta log (Ne/H)/Delta R=-0.01 dex/kpc. These flat PN gradients do not reconcile with galactic metallicity gradients flattening with time.Comment: The Astrophysical Journal, in pres