7,928 research outputs found
Preparation of catalyst coated membranes using screen printing
No full textIncludes abstract.Includes bibliographical references.Of the various types of fuel cells, Polymer Electrolyte Fuel Cells (PEFCs) have already been demonstrated in transportation appliances from light-duty vehicles to buses and in portable appliances including laptops and cell phones. A key component of a PEFC is its platinum electrocatalyst. With an estimated 75% of the world’s platinum reserves and resources in South Africa, local development of this technology will allow South Africa to become a major player in the growing hydrogen economy. This project therefore forms part of the Department of Science and Technologies strategy, to develop fuel cell technology in South Africa. More specifically, this study aims to contribute to the development of membrane electrode assembly (MEA) platform technology at the HySA/Catalysis Centre. In order to achieve this goal, a catalyst coated membrane (CCM) fabrication procedure was implemented using a newly acquired screen printer. In this procedure, catalyst ink is forced through a mesh onto a substrate, where it can then be transferred to a membrane via decal transfer to form a CCM. Two gas diffusions layers can then be placed on either side of the CCM forming a 5-layered MEA. Characterisation techniques of the catalyst ink, CCM and 5-layered MEA were successfully implemented such that future researchers can expand on the ideas. Catalyst inks with varying amounts of isopropanol, 1,2-propanediol and water were screened for their suitability for screen printing. In particular the catalyst ink rheology required for a smooth and even printed surface was determined for a given screen and squeegee combination. With all the established steps in pace, screen printing proved to be a fast and reliable approach for CCM fabrication with potential for future scale up and commercialisation. The fabricated CCMs performed on a par with a commercial Ion Power CCM, but under performed in comparison to a commercial Johnson Matthey (JM) MEA. Possible reasons for this include improved materials in the JM MEA and cell conditions favouring the JM MEA. Future projects which specifically arise from this work entail an investigation into the water management of the fuel cell environment at HySA/Catalysis, as well as a modification of the various steps in order to optimise the process and in doing so manufacture commercially viable MEAs
????????? ???????????????????????? ?????? MEA??? ????????? ??? CO2 ?????????????????? ???????????? ?????? ??????
No full textMEA??? CO2 ?????? ????????? ????????? ???????????? MEA carbamate??? ????????????, ????????? ?????? ????????? CO2??? ???????????? ???????????? ????????????. ?????????, ?????? ??????????????? MEA carbamate??? ???????????? ??????????????? ????????????. ?????? MEA??? CO2 ??????????????? ???????????????, ????????? ???????????????, ????????? ????????? ?????????, ????????? ???????????? CO2 ??????????????? ????????? ??? ??????. MEA carbamate??? ????????? ????????? ??? ?????? ??? ?????? ????????? oxazolidone, cyclic urea of trimer, HEIA(1-(2-hydroxyethyl)-2-imidazolidone), HEEDA(N-(2-hydroxyethyl)-ethylenediamine) ?????? ??????. ?????? ??????????????? MEA carbamate??? ????????? ????????? ?????? ????????? MEA??? HEEDA??? ????????? ????????? ???????????????????????? ????????? ??????????????????. CO2 loading??? ??=0.406, ??=0.6??? MEA carbamate ???????????? pipe reactor??? ?????? 130??C, 150??C??? ?????? 1, 2, 4, 6, 8??? ?????? ?????? ?????? ????????? ???????????? ?????????. ????????? ???????????????????????? ????????? MEA??? ????????? ????????? ???????????? ???????????? ??????, CO2 loading??? ????????? ????????? ???????????? MEA??? ?????? ????????? ??? ??? ?????? ????????? ??? ?????????. HEEDA??? ????????? ????????? ???????????? ??????????????????, ??=0.406, 150??C ??? ??? ?????? ????????? ?????????. ????????? CO2 ?????????????????? ???????????? ????????? ????????? ASTM ?????? ????????? ????????? CO2 loading, N2 ??????, ?????? ?????? ????????? ????????? ???????????????. ?????? ????????? ?????? ????????? ??? ??? ????????? amine??? ???????????? CO2 ?????? ????????? ????????? ???????????? ????????????
c-Fos immunoreactive cells photomicrographs and quantification in the medial amygdala (MeA).
No full text(A) c-Fos staining (dark spots) in coronal sections of MeA of the four groups: saline/non-stressed, saline/stressed, clozapine/non-stressed, clozapine/stressed. Scale bar: 100 μm. (B) The c-Fos cell counting in the MeA revealed a higher number of c-Fos cells in saline/stressed group (two-way ANOVA, *P 22]. Localization of the brain area selected for the counting of c-Fos cells is indicated in the square.</p
MEA measurements.
No full text(A) Measurement from a DIV3 neuron culture on the self-built MEA with rectangular layout show a few signals above the noise level. (B) A measurement on the same culture and electrode after DIV4. Accompanied with the progress in maturation, the spiking activity is visibly increasing. (C) Noise measurement of one electrode of the self-built MEA (dark blue) and a commercial available MEA from MCS, Reutlingen (light blue). (D) Comparison of the RMS noise values of the self-built MEA and the MEA from MCS (mean for 6 electrodes with standard deviation). The RMS noise of the self-built MEA is not significantly higher compared to the commercially available MEA from MCS. The noise measurement of the recording amplifier setup is below 1.2 μV and does not contribute significantly to the measured MEA noises.</p
Low-Impedance PEDOT:PSS MEA Integrated in a Stretchable Organ-on-Chip Device
No full textWe present the first Organ-on-Chip equipped with a low-impedance Poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) MicroElectrode Array (MEA). The novel device allows simultaneous mechanical stimulation with a stretchable PDMS membrane and electrical monitoring via the PEDOT:PSS MEA of multiple in vitro cell cultures. The surface area enhancement and the morphology of the PEDOT:PSS allows an increase of the charge injection per unit area at the electrode-electrolyte interface, resulting in significantly lower electrochemical impedance of the electrodes. In particular, at 1 kHz the fabricated PEDOT-MEA electrodes show a reduction of the overall impedance up to 99.4 and 93.3 % in comparison with benchmark TiN and Pt electrodes. The superior performance of PEDOT:PSS were also confirmed via Cyclic Voltammetry measurement, in which PEDOT:PSS showed a very large capacitive current, compared with the benchmark electrodes both in the forward and the reverse scans. The obtained results confirm the effectiveness of the proposed PEDOT:PSS coating, and introduce this material in the OOC field. Moreover, the quality and morphology of the fabricated PEDOT:PSS based electrodes were assessed via SEM imaging and Raman spectroscopy.Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Electronic Components, Technology and Material
La sicurezza incerta del confine orientale. Venezia, Friuli e Istria dalle guerre d'Italia al progetto di Palmanova (c. 1494-1593)
No full textLa tesi si aggancia idealmente al tema dei confini mediante l'approccio innovativo adoperato dalla storiografia recente, focalizzando l'attenzione sulle relazioni tra veneti e arciducali nel versante più orientale della Terraferma (Friuli e Istria, qui oggetto di analisi collegata e comparata) lungo tutto il Cinquecento. Questo periodo, connotato inizialmente dalle vicende delle guerre d'Italia, conobbe poi lunghi decenni di tensioni tra la Repubblica di Venezia e gli Asburgo, che resero incerta e quanto mai complicata la situazione del confine orientale. Le ricerche sono state condotte principalmente sui fondi dell'Archivio di Stato di Venezia
Current experiences with Internet telepathology and possible evolution in the next generation of Internet services
No full textThe last five years experience has definitely demonstrated the possible applications of the Internet for telepathology. They may be listed as follows: (a) teleconsultation via multimedia e‐mail; (b) teleconsultation via web‐based tools; (c) distant education by means of World Wide Web; (d) virtual microscope management through Web and Java interfaces; (e) real‐time consultations through Internet‐based videoconferencing. Such applications have led to the recognition of some important limits of the Internet, when dealing with telemedicine: (i) no guarantees on the quality of service (QoS); (ii) inadequate security and privacy; (iii) for some countries, low bandwidth and thus low responsiveness for real‐time applications. Currently, there are several innovations in the world of the Internet. Different initiatives have been aimed at an amelioration of the Internet protocols, in order to have quality of service, multimedia support, security and other advanced services, together with greater bandwidth
Impact of Local Microenvironments on the Selectivity of Electrocatalytic Nitrate Reduction in a BPM-MEA System
No full textElectrochemical nitrate reduction reaction (NO3RR) has garnered increasing attention as a pathway for converting a harmful pollutant (nitrate) into a value-added product (ammonia). However, high selectivity toward ammonia (NH3) is imperative for process viability. Optimizing proton availability near the catalyst is important for achieving selective NH3 production. Here, the aim is to systematically examine the impacts of proton availability on NO3RR selectivity in a bipolar membrane (BPM)-based membrane electrode assembly (MEA) system. The BPM generates a proton flux from the membrane toward the catalyst during electrolysis. Thus, the BPM-MEA system can modulate the proton flux during operation. The impact of interposer layers, proton scavenging electrolytes (CO32-), and catalyst configurations are also examined to identify which local microenvironments favor ammonia formation. It is found that a moderate proton supply allows for an increase in ammonia yield by 576% when compared to the standard MEA setup. This also results in a high selectivity of 26 (NH3 over NO2-) at an applied current density of 200 mA cm-2.,High selectivity toward ammonia is vital for the feasibility of the electrochemical nitrate reduction reaction (NO3RR). This study employs a bipolar membrane-based membrane electrode assembly system to investigate the influence of proton availability on the selectivity of NO3RR. The results underscore the pivotal importance of moderate proton supply for achieving highly selective NH3 production in NO3RR. image,
Model of the Second Most Abundant Cisplatin−DNA Cross-Link: X-ray Crystal Structure and Conformational Analysis of <i>cis</i>-[(NH<sub>3</sub>)<sub>2</sub>Pt(9-MeA-<i>N7</i>)(9-EtGH-<i>N7</i>)](NO<sub>3</sub>)·2H<sub>2</sub>O (9-MeA = 9-Methyladenine; 9-EtGH = 9-Ethylguanine)
No full textA model compound of the second most abundant DNA adduct of the
antitumor agent cisplatin has been synthesized
and structurally and spectroscopically characterized and its
conformational behavior examined:
cis-[(NH3)2Pt(9-MeA-N7)(9-EtGH-N7)](NO3)2·2H2O
(9-MeA = 9-methyladenine; 9-EtGH = 9-ethylguanine) crystallizes
in
the monoclinic system, space group
P21/n (No. 14) with a =
7.931(2), b = 11.035(3), c =
26.757(6) Å, β =
94.94(2)°, and Z = 4. The two purine bases
adopt a head-to-head orientation, with
NH2 of 9-MeA and CO of
9-EtGH being at the same side of the Pt coordination plane. A
theoretical conformational analysis of the complex
cis-[(NH3)2Pt(Ade)(Gua)]2+
(Ade = adenine; Gua = guanine) based on molecular mechanics
calculations of the
nonbonded energy has revealed four minimum-energy zones similar to
those derived previously for
cis-[(NH3)2Pt(Gua)2]2+ (Kozelka; et al. Eur.
J. Biochem. 1992, 205, 895).
This conformational analysis has allowed, together
with the calculation of chemical shifts due to ring effects, the
attribution of the two conformers observed for
cis-[(NH3)2Pt{d(ApG)}]+
by Dijt et al. (Eur. J. Biochem. 1989,
179, 344) to the two head-to-head
conformational
zones. The orientation of the two nucleobases in the crystal
structure of
cis-[(NH3)2Pt(9-MeA)(9-EtGH)]2+
corresponds, according to our analysis, roughly to that preferentially
assumed by the minor rotamer of
cis-[(NH3)2Pt{d(ApG)}]+
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