Effect of HDI-Modified GO on the Thermoelectric Performance of Poly(3,4-ethylenedioxythiophene):Poly(Styrenesulfonate) Nanocomposite Films

Composite films based on conducting polymers and carbon nanomaterials have attracted much attention for applications in various devices, such as chemical sensors, light-emitting diodes (LEDs), organic solar cells (OSCs), among others. Graphene oxide (GO) is an ideal filler for polymeric matrices due to its unique properties. However, GO needs to be functionalized to improve its solubility in common solvents and enable the processing by low-cost solution deposition methods. In this work, hexamethylene diisocyanate (HDI)-modified GO and its nanocomposites with poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) were developed, and their morphology, thermal, electrical, thermoelectrical and mechanical performance were characterized. The influence of the HDI functionalization degree and concentration on the nanocomposite properties were assessed. The HDI-GO increased the crystallinity, lamella stacking and interchain coupling of PEDOT:PSS chains. A strong improvement in electrical conductivity, thermal stability, Young's modulus and tensile strength was found, showing an optimum combination at 2 wt% loading. Drop and spin casting techniques were applied onto different substrates, and the results from deposition tests were analyzed by atomic force microscopy (AFM) and UV-vis spectroscopy. A number of parameters influencing the depositions process, namely solvent nature, sonication conditions and ozone plasma treatment, have been explored. This study paves the way for further research on conducting polymer/modified GO nanocomposites to optimize their composition and properties (i.e., transparency) for use in devices such as OSCs

Enhanced Efficiency of PTB7 : PC 61

Ternary blend polymer solar cells combining two electron-donor polymers, poly[4,8-bis[(2-ethylhexyl)oxy]benzo[1,2-b:4,5-b′]dithiophene-2,6-diyl][3-fluoro-2-[(2-ethylhexyl)carbonyl]thieno[3,4-b]thiophenediyl] (PTB7) and poly[2,5-bis(3-dodecylthiophen-2-yl)thieno[3,2-b]thiophene] (pBTTT) and [6,6]-phenyl-C61-butyric acid methyl ester (PC61BM), as electron-acceptor, were fabricated. The power conversion efficiency of the ternary cells was enhanced by 18%, with respect to the reference binary cells, for a blend composition with 25% (wt%) of pBTTT in the polymers content. The optimized device performance was related to the blend morphology, nonrevealing pBTTT aggregates, and improved charge extraction within the device

Ovarian Torsion in a Primipara Female Dog in Brazil

Background: Ovarian torsion is a condition which the ovary and the ovarian pedicle twist around the ovary suspensory ligament. No report regarding this condition was reported. The aim of the report was to describe a case of unilateral ovarian torsion in a 2-year-old primipara Golden Retriever dog.Case: A 2-year-old female primipara Golden Retriever dog weighting was referred to the Veterinary Hospital, for purulent vaginal discharge evaluation. The dog was presenting anorexia, weight loss, and intermittent diarrhea and vomiting. A cesarean section was performed nine months before her presentation and the oestrus cycle was recorded six months after the cesarean section. Discomfort was observed during the palpation of the abdomen and purulent vaginal was observed. Vaginal swab was performed and followed by cytological examination. The ultrasonographic examination was consistent with pyometra. The ovariohysterectomy was performed and were observed torsion of the left ovary. The histopathological examination of the left ovary and uterus were consistent with ovary necrosis and pyometra. Ten days after surgery the vaginal discharge had resolved and the sutures were removed. Six months postoperatively the dog revealed no further abnormalities. Grossly, the left ovary had firm consistency, dark red surface and 8 cm diameter. The histopathology examination findings were consistent with a diagnosis of diffuse necrosis of left ovary due to ovarian torsion, and uterinesuppurative inflammatory process - pyometra.Discussion: Ovarian torsion is uncommon in small animals, but can be observed high incidence in pregnant female dogs than in non-pregnant ones. The 360º an asynchronous ovarian torsion described in the present case is also an unusual condition in primipara female dogs due to the smaller stretching of the ovary suspensory ligament. The ovarian torsionis considerate an emergency condition due to acute abdominal pain. The mild abdominal discomfort observed during the physical examination was associated to pyometra or to ovarian torsion. The histopathological findings as hemorrhage, edema and necrosis were associated to compromised arterial circulation and ovarian torsion in late stage. The size of the pregnant uterus and/or the pyometra has contributed to ovary torsion. The dog of the present report had pyometra and previouscesarean sections; and these conditions may have contributed to ovarian torsion. The condition was incidentally found during the ovariohysterectomy, and the ovarian torsion diagnosis was determinate through histopathological examination. Computed tomography and magnetic resonance image could be used to diagnose, furthermore, they were not conducted due to the high cost. The leukocytosis and red blood cells Rouleaux was associated with ovarian necrosis and pyometra.Ovariohysterectomy was the treatment of choice to pyometra and ovarian torsion, and the surgery was performed without ovarian torsion reversion to minimize the reperfusion lesions. Ovarian torsion is a rare event in dogs, and it was clinically diagnosed during the surgery. To the best of the authors’ knowledge, this is the first report of ovarian torsion associate withpyometra in primipara female dogs in Brazil.Keywords: dog, obstetric, ovary, pyometra complex, endometrium

Recidiva de fibrossarcoma de aplicação em gata idosa e tratamento multimodal de excisão cirúrgica e eletroquimioterapia transoperatória (Felis catus domesticus): relato de caso

Os fibrossarcomas ou sarcomas de tecido mole de aplicação são neoplasias malignas associadas à reação imunogênica às substâncias aplicadas por via subcutânea ou intramuscular, induzindo o aumento da produção de fibroblastos e miofibroblastos de alteração do DNA, e correspondem a 46% das neoplasias cutâneas e subcutâneas em gatos. A eletroquimioterapia é uma técnica que associa a eletroporação e a quimioterapia, tendo potencial para alcançar altas taxas de remissão neoplásica, e indicada para o tratamento de neoplasias cutâneas e subcutâneas de qualquer tipo histológico. Visto que o fibrossarcoma de aplicação é uma neoplasia maligna com alto índice de invasão dos tecidos circunvizinhos, e dependendo da fase evolutiva da afecção, o tratamento deve ser multimodal, o presente trabalho teve por objetivo descrever a recidiva à longo prazo de fibrossarcoma de aplicação em gata idosa, cujo o tratamento instituto foi a excisão cirúrgica associada à eletroquimioterapia transoperatória. Gata idosa, sem raça definida, foi diagnosticada com neoformação medindo 1,5 x 1,2 cm em região abdominal esquerda, mesma região onde um ano atrás foi diagnosticado e removido fibrossarcoma de aplicação. O exame citopatológico foi sugestivo à sarcoma de tecido mole. Após a exérese da neoplasia com margens de segurança de 4 cm e eletroquimioterapia transoperatória não foi identificada presença de células neoplásicas, e o exame histopatológico foi sugestivo à recidiva de fibrossarcoma de aplicação. Concluiu-se que o diagnóstico definitivo do fibrossarcoma de aplicação foi o exame histopatológico, e em casos recidivantes, a eletroquimioterapia transoperatória induziu efeitos benéficos na manutenção de margens cirúrgicas seguras em gato idoso

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

Improving the Efficiency of Organic Solar Cells upon Addition of Polyvinylpyridine

We report on the efficiency improvement of organic solar cells (OPVs) based on the low energy gap polyfluorene derivative, APFO-3, and the soluble C60 fullerene PCBM, upon addition of a residual amount of poly (4-vinylpyridine) (PVP). We find that the addition of 1% by weight of PVP with respect to the APFO-3 content leads to an increase of efficiency from 2.4% to 2.9%. Modifications in the phase separation details of the active layer were investigated as a possible origin of the efficiency increase. At high concentrations of PVP, the blend morphology is radically altered as observed by Atomic Force Microscopy. Although the use of low molecular weight additives is a routine method to improve OPVs efficiency, this report shows that inert polymers, in terms of optical and charge transport properties, may also improve the performance of polymer-based solar cells

High-Resolution Scanning Near-Field Optical Lithography of Conjugated Polymers

The fabrication of high-resolution nanostructures in both poly(p-phenylene vinylene), PPV, and a crosslinkable derivative of poly(9,9'-dioctylfluorene), F8, using scanning near-field optical lithography, is reported. The ability to draw complex, reproducible structures with 65000 pixels and lateral resolution below 60 nm (< lambda/5) is demonstrated over areas up to 20 mu m x 20 mu m. Patterning on length-scales of this order is desirable for realizing applications both in organic nanoelectronics and nanophotonics. The technique is based on the site-selective insolubilization of a precursor polymer under exposure to the confined optical field present at the tip of an apertured near-field optical fiber probe. In the case of PPV, a leaving-group reaction is utilized to achieve insolubilization, whereas the polyfluorene is insolubilized using a photoacid initiator to create a crosslinked network in situ. For PPV, resolubilization of the features is observed at high exposure energies. This is not seen for the crosslinked F8 derivative, r-F8Ox, allowing us to pattern structures up to 200 nm in height

An Experimental Study on Step-Up DC–DC Converters for Organic Photovoltaic Cells

This work studies two circuit topologies to step-up the voltage supplied by an organic photovoltaic (OPV) cell. Comparison and validation of the proposed topologies are accomplished throughout analytical, simulation, and experimental results. Two circuit solutions were found more suitable to boost the harvested OPV cell low voltage, depending on the load condition: the classical hard-switching boost converter and a multilevel boost converter. Both experimental circuits include the drive of the MOSFET switch based on an LC oscillator at 1.2 MHz, allowing the implementation of a conversion system, supplied by voltages as low as 500 mV, with output voltages from 1.2 V up to 7 V, under solar simulator conditions. The circuit area for each converter prototype is 2.35 cm2, with a total area below 3.0 cm2 for the overall energy harvesting system, including the OPV cell, which makes this proposal an extremely compact solution for ultra-low power harvesting applications