22 research outputs found
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
Efficient and environmental-friendly perovskite solar cells via embedding plasmonic nanoparticles: an optical simulation study on realistic device architectures
Plasmonic bulk heterojunction solar cells: the role of nanoparticle ligand coating
There has been a lot of interest regarding the influence of active-layer-incorporated plasmonic nanoparticles (NPs) in the performance of bulk heterojunction organic photovoltaic (OPV) devices, while both an increase and decrease in performance have been reported. In this paper, following a systematic approach, we demonstrate strong evidence of the critical importance of the NPs’ ligand shell on the device performance. In particular, it is argued that the plasmonic effect accountable for the performance enhancement takes place only in the case in which the NP’s core is in direct contact with the active layer polymer donor. This can be achieved with the utilization of either ligand-free NPs or NPs terminated with the same polymer donor as the active layer. Using this concept we achieved an enhanced efficiency of 7.16% in OPV devices incorporating the poly(3-hexylthiophene-2,5-diyl) (P3HT):indene-C60 bisadduct (ICBA) active layer. On the contrary, devices with ligand-terminated Au NPs show lower performance, even compared with the reference, NP-free, device due to the deteriorated active layer morphology attained, which leads to exciton quenching. These new insights into the plasmonic light-harvesting technology could shed light on the existing controversy and provide guidelines for device design and fabrication
Enhancement of the Efficiency and Stability of Organic Photovoltaic Devices via the Addition of a Lithium-Neutralized Graphene Oxide Electron-Transporting Layer
Lithium-neutralized
graphene oxide (GO-Li) was spin coated between
the photoactive layer and the metal oxide electron-transporting layer
(ETL) as an additional interlayer in organic photovoltaic devices.
The introduction of GO-Li leads to a superior interface between the
ETL and the photoactive layer. Combined with the reduced work function
(WF) of GO-Li (4.3 eV), which is a perfect match with the fullerene
acceptor material LUMO level, PCDTBT:PC<sub>71</sub>BM-based air-processed
devices with a GO-Li layer exhibited a significant enhancement in
their power conversion efficiency (PCE) from 5.51 to 6.29% (14.2%
increase over that of comparable devices without the graphene-based
interfacial layer). Furthermore, the GO-Li device exhibited stability
higher than that of the device without the interlayer due to the fact
that the GO-Li acts as an internal shield against humidity, protecting
the air sensitive polymers and improving the lifetime of the devices
Solution Processed CH<sub>3</sub>NH<sub>3</sub>PbI<sub>3–<i>x</i></sub>Cl<sub><i>x</i></sub> Perovskite Based Self-Powered Ozone Sensing Element Operated at Room Temperature
Hybrid
lead halide spin coated perovskite films have been successfully
tested as portable, flexible, operated at room temperature, self-powered,
and ultrasensitive ozone sensing elements. The electrical resistance
of the hybrid lead mixed halide perovskite (CH<sub>3</sub>NH<sub>3</sub>PbI<sub>3–<i>x</i></sub>Cl<sub><i>x</i></sub>) sensing element, was immediately decreased when exposed to
an ozone (O<sub>3</sub>) environment and manage to recover its pristine
electrical conductivity values within few seconds after the complete
removal of ozone gas. The sensing measurements showed different response
times at different gas concentrations, good repeatability, ultrahigh
sensitivity and fast recovery time. To the best of our knowledge,
this is the first time that a lead halide perovskite semiconductor
material is demonstrating its sensing properties in an ozone environment.
This work shows the potential of hybrid lead halide based perovskites
as reliable sensing elements, serving the objectives of environmental
control, with important socioeconomic impact
Enhanced Stability of Aluminum Nanoparticle-Doped Organic Solar Cells
Enhancement of the stability of bulk
heterojunction (BHJ) organic photovoltaic (OPV) devices is reported
by the addition of surfactant-free aluminum (Al) nanoparticles (NPs)
into the photoactive layer. The universality of the effect is demonstrated
for two different BHJ systems, namely, the well-studied poly(3-hexylthiophene-2,5-diyl):phenyl-C61-butyric
acid methyl ester (P3HT:PCBM) as well as the high efficient poly[<i>N</i>-9′-heptadecanyl-2,7-carbazole-<i>alt</i>-5,5-(4′,7′-di-2-thienyl-2′,1′,3′-benzothiadiazole)]:[6,6]-phenyl-C71-butyric
acid methyl ester (PCDTBT:PC<sub>71</sub>BM). It is shown that the
lifetime of the devices with Al NPs, operating under continuous one-sun
illumination in ambient conditions, is more than three times longer
compared to the reference devices. Using complementary analytical
techniques for in situ studies, we have explored the underlying mechanisms
behind the observed stability improvement in the case of the P3HT:PCBM
system. In particular, laser-induced fluorescence (LIF), photoluminescence
decay and Fourier transform infrared (FTIR) spectroscopy experiments
were performed and complemented with device degradation electrical
measurements. It is found that the embedded Al NPs act as performance
stabilizers, giving rise to enhanced structural stability of the active
blend. Furthermore, it is revealed that the observed improvement can
also be ascribed to NP-mediated mitigation of the photo-oxidation
effect. This study addresses a major issue in OPV devices, that is,
photoinduced stability, indicating that the exploitation of Al NPs
could be a successful approach toward fabricating OPVs exhibiting
long-term operating lifetimes