Effect of the anodization voltage on the porewidening rate of nanoporous anodic alumina

A detailed study of the pore-widening rate of nanoporous anodic alumina layers as a function of the anodization voltage was carried out. The study focuses on samples produced under the same electrolyte and concentration but different anodization voltages within the self-ordering regime. By means of ellipsometry-based optical characterization, it is shown that in the porewidening process, the porosity increases at a faster rate for lower anodization voltages. This opens the possibility of obtaining three-dimensional nanostructured nanoporous anodic alumina with controlled thickness and refractive index of each layer, and with a refractive index difference of up to 0.24 between layers, for samples produced with oxalic acid electrolytes

Photonic stop bands in quasi-random nanoporous anodic alumina structures

The existence of photonic stop bands in the self-assembled arrangement of pores in porous anodic alumina structures is investigated by means of rigorous 2D finite- difference time-domain calculations. Self-assembled porous anodic alumina shows a random distribution of domains, each of them with a very definite triangular pattern, constituting a quasi-random structure. The observed stop bands are similar to those of photonic quasicrystals or random structures. As the pores of nanoporous anodic alumina can be infiltrated with noble metals, nonlinear or active media, it makes this material very attractive and cost-effective for applications including inhibition of spontaneous emission, random lasing, LEDs and biosensors

Diphenylphenoxy-Thiophene-PDI Dimers as Acceptors for OPV Applications with Open Circuit Voltage Approaching 1 Volt

Two new perylenediimides (PDIs) have been developed for use as electron acceptors in solution-processed bulk heterojunction solar cells. The compounds were designed to exhibit maximal solubility in organic solvents, and reduced aggregation in the solid state. In order to achieve this, diphenylphenoxy groups were used to functionalize a monomeric PDI core, and two PDI dimers were bridged with either one or two thiophene units. In photovoltaic devices prepared using PDI dimers and a monomer in conjunction with PTB7, it was found that the formation of crystalline domains in either the acceptor or donor was completely suppressed. Atomic force microscopy, X-ray diffraction, charge carrier mobility measurements and recombination kinetics studies all suggest that the lack of crystallinity in the active layer induces a significant drop in electron mobility. Significant surface recombination losses associated with a lack of segregation in the material were also identified as a significant loss mechanism. Finally, the monomeric PDI was found to have sub-optimum LUMO energy matching the cathode contact, thus limiting charge carrier extraction. Despite these setbacks, all PDIs produced high open circuit voltages, reaching almost 1 V in one particular caseThis work was supported by the Spanish Ministry of Economy, Industry and Competitiveness (MEIC) (TEC2015-71324-R, CTQ2014-55798-R and TEC2015-71915-REDT (MINECO/FEDER))This work was supported by the Catalan Institution for Research and Advanced Studies (ICREA) (ICREA “Academia Award”, AGAUR 2017 SGR 017SGR1527

Echinoderms from the Museum of Zoology from the Universidad de Costa Rica

El Museo de Zoología de la Universidad de Costa Rica (MZUCR) se funda en 1966 y alberga la colección de organismos vertebrados e invertebrados más completa de Costa Rica. El MZUCR cuenta actualmente con 24 colec-ciones que contienen más de cinco millones de especíme-nes, y más de 13 000 especies identificadas. Las primeras colecciones datan 1960 e incluyen peces, reptiles, anfibios, poliquetos, crustáceos y equinodermos. Para este último grupo, el MZUCR posee un total de 157 especies, en 1 173 lotes y 4 316 ejemplares. Estas 157 especies representan el 54% del total de especies de equinodermos que posee Costa Rica (293 especies). El resto de especies están repar-tidas en las siguientes instituciones: Academia de la Cien-cias de California (CAS) (4.8%), Instituto Oceanográfico Scripps (SIO) (5.2%), en la Colección Nacional de equino-dermos “Dra. Ma. Elena Caso” de la Universidad Nacional Autónoma de México (ICML-UNAM) (12.7%), Museo de Zoología Comparada de Harvard (MZC) (19.2%), y en el Museo Nacional de Historia Natural del Instituto Smithso-niano (USNM) (35.1%). Es posible que haya material de Costa Rica en el Museo de Historia Natural de Dinamarca (NCD) y en el Museo de Historia Natural de los Ángeles (LACM), sin embargo, no hubo acceso a dichas coleccio-nes. A su vez hay 9.6% de especies que no aparecen en ningún museo, pero están reportadas en la literatura. Con base en esta revisión de colecciones se actualizó el listado taxonómico de equinodermos para Costa Rica que consta de 293 especies, 152 géneros, 75 familias, 30 órdenes y cinco clases. La costa Pacífica de Costa Rica posee 153 especies, seguida por la isla del Coco con 134 y la costa Caribe con 65. Holothuria resultó ser el género más rico con 25 especies.The Museum of Zoology, Universidad de Costa Rica (MZUCR) was founded in 1966 and houses the most complete collection of vertebrates and invertebrates in Costa Rica. The MZUCR currently has 24 collections containing more than five million specimens, and more than 13 000 species. The earliest collections date back to 1960 and include fishes, reptiles, amphibians, polychaetes, crustaceans and echinoderms. For the latter group, the MZUCR has a total of 157 species, in 1 173 lots and 4 316 specimens. These 157 species represent 54% of the total species of echino-derms from Costa Rica. The remaining species are distributed in the following institutions: California Academy of Sciences (CAS) (4.8%), Scripps Oceanographic Institute (SIO) (5.2%), National Echinoderm Collection “Dr. Ma. Elena Caso” from the National Autonomous University of Mexico (ICML-UNAM) (12.7%), the National Museum of Natural History, Smithsonian Institute (USNM) (35.1%), and the Harvard Museum of Comparative Zoology (19.2%). There may be material from Costa Rica in the Natural History Museum of Denmark (NCD) and the Natural History Museum of Los Angeles (LACM), however, there was no access to such collections. There are 9.6% that do not appear in museums, but are reported in the literature. Based on this revision, the taxonomic list of echinoderms for Costa Rica is updated to 293 species, 152 genera, 75 families, 30 orders and 5 classes. The Pacific coast of Costa Rica has 153 species, followed by the Isla del Coco with 134 and the Caribbean coast with 65. Holothuria is the most diverse genus with 25 species.UCR::Vicerrectoría de Docencia::Ciencias Básicas::Facultad de Ciencias::Escuela de BiologíaUCR::Vicerrectoría de Investigación::Unidades de Investigación::Ciencias Básicas::Centro de Investigación en Ciencias del Mar y Limnología (CIMAR)UCR::Vicerrectoría de Investigación::Unidades de Investigación::Artes y Letras::Museo de la Universidad de Costa Ric

Real-Time Monitoring of Doxorubicin Release from Hybrid Nanoporous Anodic Alumina Structures

This work demonstrates an advanced approach to fabricate Hybrid nanoporous anodic alumina gradient-index filters (Hy-NAA-GIFs) through a heterogeneous anodization process combining sinusoidal current-density anodization and constant potential anodization. As a result, the hybrid structure obtained reveals a single photonic stopband (PSB), which falls within the absorption region of the drug molecule and the intensity of the spectrum that are far from such absorption range. The prepared structures were loaded with the doxorubicin (DOX) drug through the drop-casting method, which allows for evaluating the maximum reflectance of the relative height of the PSB with the average reflectance of the spectrum intensity. Thereafter, this property has been applied in a flow cell setup connected to a reflectance spectrophotometer where different drug-loaded samples were placed to study the behavior and kinetics of the drug release in real-time by varying two parameters, i.e., different pore length and flow rates. As such, obtained results were analyzed with a model that includes a sum of two inverted exponential decay functions with two different characteristic time releases. Overall, this study opens up several possibilities for the Hy-NAA-GIFs to study the drug kinetics from nanoporous structures

Advances in Optical Biosensors and Sensors Using Nanoporous Anodic Alumina

This review paper focuses on recent progress in optical biosensors using self-ordered nanoporous anodic alumina. We present the fabrication of self-ordered nanoporous anodic alumina, surface functionalization, and optical sensor applications. We show that self-ordered nanoporous anodic alumina has good potential for use in the fabrication of antibody-based (immunosensor), aptamer-based (aptasensor), gene-based (genosensor), peptide-based, and enzyme-based optical biosensors. The fabricated optical biosensors presented high sensitivity and selectivity. In addition, we also showed that the performance of the biosensors and the self-ordered nanoporous anodic alumina can be used for assessing biomolecules, heavy ions, and gas molecules

Foreword Special Issue on the 2nd Latin American Electron Device Conference

This Special Issue is devoted to research and development in the field of electron devices science and technology. We have selected a number of high quality papers presented at the $2^{nd}$ Latin American Electron Device Conference (LAEDC 2020). The $2^{nd}$ LAEDC was held in San Jose, Costa Rica from the $25^{th}$ to 28 February, 2020 and was sponsored by the IEEE Electron Devices Society

Recent Advances in Nanoporous Anodic Alumina: Principles, Engineering, and Applications

The development of aluminum anodization technology features many stages. With the story stretching for almost a century, rather straightforward—from current perspective—technology, raised into an iconic nanofabrication technique. The intrinsic properties of alumina porous structures constitute the vast utility in distinct fields. Nanoporous anodic alumina can be a starting point for: Templates, photonic structures, membranes, drug delivery platforms or nanoparticles, and more. Current state of the art would not be possible without decades of consecutive findings, during which, step by step, the technique was more understood. This review aims at providing an update regarding recent discoveries—improvements in the fabrication technology, a deeper understanding of the process, and a practical application of the material—providing a narrative supported with a proper background

Foreword Special Issue on the 4th Latin American Electron Device Conference

This Special Issue is devoted to research and development in the field of electron devices science and technology. We have selected a number of high-quality papers presented at the 4th Latin American Electron Device Conference (LAEDC 2022). The forth LAEDC edition took place in Puebla, Mexico, from July 4th to 6th, 2022 and was sponsored by the IEEE Electron Devices Society