700 research outputs found

    Electrochemical Stability and Degradation of Commercial Pd/C Catalyst in Acidic Media

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    Palladium has attracted significant attention as a catalyst or co-catalyst for many electrochemical reactions in energy conversion devices. We have studied electrochemical stability of a commercial Pd/C sample in an acidic electrolyte by exposing it to an accelerated stress test (AST) to mimic potential spikes in fuel cells and electrolyzers during start/stop events. AST consisted of extensive rapid potential cycling (5000 cycles, 1 V/s) in two potential regions, namely AST1 was performed between 0.4 and 1.4 VRHE, while AST2 was performed between 0.05 and 1.4 VRHE. Degradation of Pd/C was monitored by the changes in Pd electrochemical surface area, while the hydrogen evolution reaction (HER) was used as a test reaction to observe the corresponding impact of the degradation on the activity of Pd/C. Significant Pd/C degradation and HER activity loss were observed in both potential regions. Coupling of the electrochemical flow cell with an inductively coupled plasma mass spectrometry device showed substantial Pd dissolution during both ASTs. Identical location scanning electron microscopy revealed that Pd dissolution is followed by redeposition during both ASTs, resulting in particle size growth. Particle size growth was seen as especially dramatic in the case of AST2, when particularly large Pd nanostructures were obtained on top of the catalyst layer. According to the results presented in this work, (in)stability of Pd/C and other Pd-based nanocatalysts should be studied systematically as it may present a key factor limiting their application in energy conversion devices

    Neurons of the Dentate Molecular Layer in the Rabbit Hippocampus

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    The molecular layer of the dentate gyrus appears as the main entrance gate for information into the hippocampus, i.e., where the perforant path axons from the entorhinal cortex synapse onto the spines and dendrites of granule cells. A few dispersed neuronal somata appear intermingled in between and probably control the flow of information in this area. In rabbits, the number of neurons in the molecular layer increases in the first week of postnatal life and then stabilizes to appear permanent and heterogeneous over the individuals’ life span, including old animals. By means of Golgi impregnations, NADPH histochemistry, immunocytochemical stainings and intracellular labelings (lucifer yellow and biocytin injections), eight neuronal morphological types have been detected in the molecular layer of developing adult and old rabbits. Six of them appear as interneurons displaying smooth dendrites and GABA immunoreactivity: those here called as globoid, vertical, small horizontal, large horizontal, inverted pyramidal and polymorphic. Additionally there are two GABA negative types: the sarmentous and ectopic granular neurons. The distribution of the somata and dendritic trees of these neurons shows preferences for a definite sublayer of the molecular layer: small horizontal, sarmentous and inverted pyramidal neurons are preferably found in the outer third of the molecular layer; vertical, globoid and polymorph neurons locate the intermediate third, while large horizontal and ectopic granular neurons occupy the inner third or the juxtagranular molecular layer. Our results reveal substantial differences in the morphology and electrophysiological behaviour between each neuronal archetype in the dentate molecular layer, allowing us to propose a new classification for this neural population

    The influence of semantic and phonological factors on syntactic decisions: An event-related brain potential study

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    During language production and comprehension, information about a word's syntactic properties is sometimes needed. While the decision about the grammatical gender of a word requires access to syntactic knowledge, it has also been hypothesized that semantic (i.e., biological gender) or phonological information (i.e., sound regularities) may influence this decision. Event-related potentials (ERPs) were measured while native speakers of German processed written words that were or were not semantically and/or phonologically marked for gender. Behavioral and ERP results showed that participants were faster in making a gender decision when words were semantically and/or phonologically gender marked than when this was not the case, although the phonological effects were less clear. In conclusion, our data provide evidence that even though participants performed a grammatical gender decision, this task can be influenced by semantic and phonological factors

    A Fuzzy Inference System for Closed-Loop Deep Brain Stimulation in Parkinson’s Disease

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    Parkinsons disease is a complex neurodegenerative disorder for which patients present many symptoms, tremor being the main one. In advanced stages of the disease, Deep Brain Stimulation is a generalized therapy which can significantly improve the motor symptoms. However despite its beneficial effects on treating the symptomatology, the technique can be improved. One of its main limitations is that the parameters are fixed, and the stimulation is provided uninterruptedly, not taking into account any fluctuation in the patients state. A closed-loop system which provides stimulation by demand would adjust the stimulation to the variations in the state of the patient, stimulating only when it is necessary. It would not only perform a more intelligent stimulation, capable of adapting to the changes in real time, but also extending the devices battery life, thereby avoiding surgical interventions. In this work we design a tool that learns to recognize the principal symptom of Parkinsons disease and particularly the tremor. The goal of the designed system is to detect the moments the patient is suffering from a tremor episode and consequently to decide whether stimulation is needed or not. For that, local field potentials were recorded in the subthalamic nucleus of ten Parkinsonian patients, who were diagnosed with tremor-dominant Parkinsons disease and who underwent surgery for the implantation of a neurostimulator. Electromyographic activity in the forearm was simultaneously recorded, and the relation between both signals was evaluated using two different synchronization measures. The results of evaluating the synchronization indexes on each moment represent the inputs to the designed system. Finally, a fuzzy inference system was applied with the goal of identifying tremor episodes. Results are favourable, reaching accuracies of higher 98.7 % in 70 % of the patients.Centro de Investigación Biomédica en RedDepto. de Psicología Experimental, Procesos Cognitivos y LogopediaDepto. de Radiología, Rehabilitación y FisioterapiaFac. de PsicologíaFac. de MedicinaTRUEpu

    Extra-uterine (abdominal) full term foetus in a 15-day pregnant rabbit

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    [EN] Background: While ectopic pregnancies account for 1-2% of all pregnancies, abdominal pregnancy is extremely rare, accounting for approximately 1% of ectopic pregnancies. Extrauterine abdominal pregnancy is defined as the implantation and development of an embryo in the peritoneal cavity. The present report is the first of an incidental case of abdominal pregnancy within four full-term foetus simultaneously with 2 weeks of physiological gestation in a healthy doe rabbit. Case presentation: The doe was born on November 3, 2014 and the first partum took place on May 18, 2015. The doe had previously delivered and weaned an average of 12.0 +/- 1.41 live kits at birth (no stillbirths were recorded) during 5 consecutive pregnancies. The last mating was on December 18, 2015 and the detection of pregnancy failure post breeding (by abdominal palpation) on December 31, 2015. Then, the doe was artificially inseminated on January 27, 2016, diagnosed pregnant on February 11, 2016 and subsequently euthanized to recover the foetus. A ventral midline incision revealed a reproductive tract with 12 implantation sites with 15 days old foetus and 4 term foetus in abdominal cavity. There were two foetus floating on either side of the abdominal cavity and two suspended near the greater curvature of the stomach. They were attached to internal organs by means of one or 2 thread-like blood vessels that linked them to the abdominal surfaces. Conclusions: In our opinion a systematic monitoring of rabbit breeding should be included to fully understand and enhance current knowledge of this phenomenon of abdominal pregnancy.This work was supported by Spanish Research Project AGL2014-53405-C2-1-P (Interministerial Commission on Science and Technology).Marco-Jiménez, F.; Garcia-Dominguez, X.; Valdes-Hernández, J.; Vicente Antón, JS. (2017). Extra-uterine (abdominal) full term foetus in a 15-day pregnant rabbit. BMC Veterinary Research. 13:1-4. https://doi.org/10.1186/s12917-017-1229-7S1413Petracci M, Bianchi M, Cavani C. Development of rabbit meat products fortified with n-3 polyunsaturated fatty acids. Nutrients. 2009;1:111–8.FAOSTAT (Food and Agriculture Organization of the United Nations, authors). Available online: http://faostat.fao.org/site/569/DesktopDefault.aspx?PageID=569#ancor . Accessed Sept 2012.Segura Gil P, Peris Palau B, Martínez Martínez J, Ortega Porcel J, Corpa Arenas JM. Abdominal pregnancies in farm rabbits. Theriogenology. 2004;62:642–51.Rosell JM, de la Fuente LF. Culling and mortality in breeding rabbits. Prev Vet Med. 2009;88:120–7.Tena-Betancourt E, Tena-Betancourt CA, Zúniga-Muñoz AM, Hernández-Godínez B, Ibáñez-Contreras A, Graullera-Rivera V. Multiple extrauterine pregnancy with early and near full-term mummified foetuses in a New Zealand white rabbit (Oryctolagus Cuniculus). J Am Assoc Lab Anim Sci. 2014;53:204–7.Sánchez JP, Theilgaard P, Mínguez C, Baselga M. Constitution and evaluation of a long-lived productive rabbit line. J Anim Sci. 2008;86:515–25.Savietto D, Friggens NC, Pascual JJ. Reproductive robustness differs between generalist and specialist maternal rabbit lines: the role of acquisition and allocation of resources. Genet Sel Evol. 2015;47:2.Viudes-de-Castro MP, Vicente JS. Effect of sperm count on the fertility and prolificity rates of meat rabbits. Anim Reprod Sci. 1997;46:313–9.Marco-Jiménez F, Garcia-Dominguez X, Jimenez-Trigos E, Vera-Donoso CD, Vicente JS. Vitrification of kidney precursors as a new source for organ transplantation. Cryobiology. 2015;70:278–82.Garcia-Dominguez X, Vera-Donoso CD, Jimenez-Trigos E, Vicente JS, Marco-Jimenez. First steps towards organ banks: vitrification of renal primordial. Cryo Letters. 2016;37:47–52.Arvidsson A. Extra-uterine pregnancy in a rabbit. Vet Rec. 1998;142:176.Glišić A, Radunović N, Atanacković J. Methotrexate and fallopian tubes in ectopic pregnancy. Acta veterinaria. 2006;56:375–82.Nwobodo EI. Abdominal pregnancy. A case report. Ann Afr Med. 2004;3:195–6.Nassali MN, Benti TM, Bandani-Ntsabele M, Musinguzi E. A case report of an asymptomatic late term abdominal pregnancy with a live birth at 41 weeks of gestation. BMC Res Notes. 2016;9:31.Baffoe P, Fofie C, Gandau BN. Term abdominal pregnancy with healthy new-born: a case report. Ghana Med J. 2011;45:81–3.Eleje GU, Adewae O, Osuagwu IK, Obianika CE. Post-date extra-uterine abdominal pregnancy in a rhesus negative Nullipara with successful outcome: a case report. J Women's Health. 2013;6:2.Hong CC, Armstrong ML. Ectopic pregnancy in 2 guinea-pigs. Lab Anim. 1978;12:243–4.Peters LJ. Abdominal pregnancy in a golden hamster (Mesocricetus Auratus). Lab Anim Sci. 1982;32:392–3.Xiccato G, Trocino A, Boiti C, Brecchia G. Reproductive rhythm and litter weaning age as they affect rabbit doe performance and body energy balance. Anim Sci. 2005;81:289–96.Fortun-Lamothe L, De Rochambeau H, Lebas F, Tudela F. Influence of the number of suckling young on reproductive performance in intensively reared rabbits does. In: Blasco A, editor. Proceedings of the 7th world rabbit congress; 2002. p. 125–32

    Regulation of PTP1D mRNA by Peptide Growth Factors in the Human Endometrial Cell Line HEC-1-A

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    Objective: To assess, in the human endometrial cell line HEC-1-A, the presence of protein tyrosine phosphatase 1D (PTDP1D) and the possible regulation of its mRNA expression by mitogens such as forskolin (an agent that increases intracellular cyclic adenosine monophosphate [cAMP] levels), epidermal growth factor (EGF), and insulin-like growth factor-I (IGF-I). Methods: Cells were grown to confluence and maintained in serum-free media for 24 hours before treatment. Cells were exposed to forskolin, EGF, and IGF-I for increasing time periods (0, 1, 3, 6, and 24 hours), and PTP1D mRNA expression was determined by Northern blot analysis. In addition, cells were incubated with increasing doses of forskolin (final concentrations: 1, 5, 10, 20, and 30 μmol/L0 for 6 hours. Results: When treated with the various mitogens, cells increased their stimulation of PTP1D mRNA expression in a time- and dose-dependent fashion. Specifically, forskolin, EGF, and IGF-I induced maximal mRNA expression at 6, 3, and 6 hours, respectively. Expression induced by forskolin, EGF, and IGF-I was five, three, and six times control levels, respectively. At a dose of 10 μmol/L, forskolin induced PTP1D mRNA expression almost two times higher than control values. Conclusion: These data suggest that in human endometrial carcinomas, cAMP, EGF, and IGF-I may regulate the expression of PTP1D mRNA, which may, in turn, play a role in uncontrolled cell proliferation and neoplastic transformation.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/68928/2/10.1177_107155769700400608.pd

    Exon sequence requirements for excision in vivo of the bacterial group II intron RmInt1

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    <p>Abstract</p> <p>Background</p> <p>Group II intron splicing proceeds through two sequential transesterification reactions in which the 5' and 3'-exons are joined together and the lariat intron is released. The intron-encoded protein (IEP) assists the splicing of the intron <it>in vivo </it>and remains bound to the excised intron lariat RNA in a ribonucleoprotein particle (RNP) that promotes intron mobility. Exon recognition occurs through base-pairing interactions between two guide sequences on the ribozyme domain dI known as EBS1 and EBS2 and two stretches of sequence known as IBS1 and IBS2 on the 5' exon, whereas the 3' exon is recognized through interaction with the sequence immediately upstream from EBS1 [(δ-δ' interaction (subgroup IIA)] or with a nucleotide [(EBS3-IBS3 interaction (subgroup IIB and IIC))] located in the coordination-loop of dI. The δ nucleotide is involved in base pairing with another intron residue (δ') in subgroup IIB introns and this interaction facilitates base pairing between the 5' exon and the intron.</p> <p>Results</p> <p>In this study, we investigated nucleotide requirements in the distal 5'- and 3' exon regions, EBS-IBS interactions and δ-δ' pairing for excision of the group IIB intron RmInt1 <it>in vivo</it>. We found that the EBS1-IBS1 interaction was required and sufficient for RmInt1 excision. In addition, we provide evidence for the occurrence of canonical δ-δ' pairing and its importance for the intron excision <it>in vivo.</it></p> <p>Conclusions</p> <p>The excision <it>in vivo </it>of the RmInt1 intron is a favored process, with very few constraints for sequence recognition in both the 5' and 3'-exons. Our results contribute to understand how group II introns spread in nature, and might facilitate the use of RmInt1 in gene targeting.</p
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