A photoelectrochemical study of Cu(In
,Ga)Se
2 (CIGS) thin films in 0.5
M H
2SO
4 is presented in this work. CIGS thin films were obtained by electrodeposition of CuInSe
2 (CIS) and the composition ...was adjusted by physical vapor deposition (PVD) to obtain CuIn
1−
x
Ga
x
Se
2. Photo-electrodes were prepared using CIGS thin films. These electrodes exhibited cathodic photoresponse associated with the hydrogen evolution occurring at 0.3
V more positive potential than the potential observed for the hydrogen evolution in the dark. The production of hydrogen by CIGS films at different potentials was estimated by coulometric measurements, showing that under illumination the quantity of hydrogen produced was two orders of magnitude higher than the hydrogen produced in the dark.
Transporte de voz en entornos IPV4 e IPV6 Gamboa, Fausto A; López S., Danilo A; Salcedo P., Octavio J
Vision Electronica,
01/2012, Letnik:
6, Številka:
1
Journal Article
Recenzirano
Odprti dostop
En este artículo se expone el estado actual de las redes de voz y su funcionamiento sobre redes IP versión 6, las arquitecturas en las que se puede implementar y los protocolos que las soportan. Se ...indican sus ventajas respecto de la versión 4 del protocolo, gracias a las características que mejoran la calidad del servicio. Se evalúa el desempeño, teniendo en cuenta el retardo, jitter y la pérdida de paquetes.
Pt–MoO3 was synthesized by microwave-assisted chemical reduction. The physicochemical characterization showed that the electrocatalyst contained nanoparticles of Pt and clusters of MoO3. The average ...particle size of the catalytic material was 2.5 nm. The electrochemical results showed that the Pt–MoO3/C was suitable to carry out the electrooxidation reactions of ethanol and methanol indistinctly, avoiding CO poisoning. It was possible to compare the results with commercial Pt/C. The synthesized material showed a better electrochemical performance. Different simulations were performed using the Nernst equation to evaluate the influence of temperature, internal resistance, and the current density losses as a function of the fuel used. The theoretical results indicated that the electrical power of the mono-cell improves by 21.5% when the energy vector is changed from methanol to ethanol at the maximum power point, obtaining an electrical potential change ΔE = 87.02 mV and a variation of the electric power of Δp = 114.14 mW cm−2. The use of dual fuels could improve the performance of experimental fuel cells.
Display omitted
•Nanostructured Pt–MoO3 was synthesized by microwave-assisted chemical reduction.•Pt–MoO3/C can electrooxidize methanol and ethanol in dual fuel cells.•Pt–MoO3/C was tolerant to CO poisoning.•Electrooxidation reaction of methanol is more complex than ethanol.•Simulation showed better performance when fuels were used sequentially.
Management of adults with atrial fibrillation (AF) or atrial flutter in the emergency department (ED) includes rate reduction, cardioversion, and stroke prevention. Different approaches to these ...components of care may lead to variation in frequency of hospitalization and stroke prevention actions, with significant implications for patient experience, cost of care, and risk of complications. Standardization using evidence-based recommendations could reduce variation in management, preventable hospitalizations, and stroke risk.
We describe the rationale for our ED-based AF treatment recommendations. We also describe the development of an electronic clinical decision support system (CDSS) to deliver these recommendations to emergency physicians at the point of care. We implemented the CDSS at three pilot sites to assess feasibility and solicit user feedback. We will evaluate the impact of the CDSS on hospitalization and stroke prevention actions using a stepped-wedge cluster randomized pragmatic clinical trial across 13 community EDs in Northern California.
We hypothesize that the CDSS intervention will reduce hospitalization of adults with isolated AF or atrial flutter presenting to the ED and increase anticoagulation prescription in eligible patients at the time of ED discharge and within 30 days. If our hypotheses are confirmed, the treatment protocol and CDSS could be recommended to other EDs to improve management of adults with AF or atrial flutter.
ClinicalTrials.gov NCT05009225 . Registered on 17 August 2021.
This work describes the electrochemical performance of a novel sensor based on two-dimensional ZnO and activated by the plasmonic effect to calculate the ethanol content in bio-alcohol samples. The ...ZnO was prepared in a coffee extract at 90 °C. XRD and TEM showed the formation of hexagonal phase ZnO and its two-dimensional morphology, respectively. The sensor was formed by depositing the semiconductor on a sterling silver sheet. The sensor was immersed in 1 M KOH at 25 °C and illuminated with visible light to produce the plasmonic effect. The electrochemical analysis showed that the plasmonic effect activated the complex redox reactions of ethanol/CO2. A Figure of Merit of the sensor was proposed to obtain the calibration curve and calculate the molar concentration of ethanol in four bio-alcohol samples obtained from artisanal production. The accurate content of ethanol in each sample was measured by gas chromatography and was compared with the calculated values. The results show the feasibility of using sensors activated by the plasmonic effect to calculate the ethanol content in alcohols.
Methanol electro-oxidation was investigated on PtSnO2/C based electrocatalyst in acidic solution. This study was focused on the use of this material as anodic active material for potential ...applications in direct methanol fuel cells. PtSnO2/C nanoparticles were prepared using a microwave-assisted synthesis. Physic-chemical and electrochemical characterizations were carried out by XRD, TEM, EDS, cyclic voltammetry and chronoamperometric studies. TEM analysis revealed that PtSnO2/C electrocatalyst is formed by well dispersed nanoparticles with average particle size around 2.2nm. The results showed that synthesized PtSnO2/C has better electrochemical characteristics than commercial PtRu/C for methanol oxidation. It was found that PtSnO2/C showed less methanol oxidation reaction onset potential than PtRu/C. The investigation of some kinetic parameters like Tafel slope and charge transfer coefficient showed that PtSnO2/C has a Pt based electrocatalyst performance associated to the bi-functional process able to oxidize CH3OH and COads, it is probably activated by the co-existence of SnO2 phase.
► PtSnO2/C electrocatalyst was prepared by microwave-assisted chemical reduction. ► Low Pt content electrocatalyst showed adequate characteristics to oxidize methanol. ► PtSnO2/C showed better methanol oxidation characteristics than commercial PtRu/C.
Oxygen evolution reaction was studied in alkaline medium on a nickel hydroxide electrode modified by electroless cobalt coating. The presence of cobalt coating at the surface of nickel hydroxide can ...increase the oxygen evolution overpotential promoting full charge of the electrode. It has been found that the oxygen evolution potential at this kind of electrode was apparently higher than that on the nickel hydroxide electrode added with cobalt powder as a conductor. Kinetic studies have also shown that this kind of electrode has a greater Tafel slope for oxygen evolution reaction. The mechanism of oxygen evolution has also been discussed.
The corrosion resistance behavior of Ni–Co–B coated carbon steel, Al 6061 alloy and 304 stainless steel was evaluated in simulated proton exchange membrane fuel cell (PEMFC) environment. The phase ...structure of the NiCoB based alloy was determined by Rietveld analysis. The PEMFC environment was constituted of 0.5
M H
2SO
4 at 60
°C and the evaluation techniques employed included potentiodynamic polarization, linear polarization resistance, open circuit potential measurements and electrochemical impedance spectroscopy. The results showed that in all cases the corrosion resistance of the Ni–Co–B coating was higher than that of the uncoated alloys; about two orders of magnitude with respect to carbon steel and an order of magnitude compared to 304 stainless steel. Except for the uncoated 304 type stainless steel, the polarization curves for the coated specimens did not exhibit a passive region but only anodic dissolution. The corrosion potential value,
E
corr, was always nobler for the coated samples than for the uncoated specimens. This was true for the stainless steel in the passive region, but in the active state for the carbon steel and Al 6061 alloy. The corrosion of the underlying alloy occurred due to filtering of the solution through coating defects like microcracks, pinholes, etc. During the filtering process the
E
corr value of the coating decreased slowly until it reached a steady state value, close to the
E
corr value of the underlying alloy.
Background Supine hypertension affects a majority of patients with autonomic failure; it is associated with end-organ damage and can worsen daytime orthostatic hypotension by inducing pressure ...diuresis and volume loss during the night. Because sympathetic activation prevents blood pressure (BP) from falling in healthy subjects exposed to heat, we hypothesized that passive heat had a BP-lowering effect in patients with autonomic failure and could be used to treat their supine hypertension. Methods and Results In Protocol 1 (n=22), the acute effects of local heat (40-42°C applied with a heating pad placed over the abdomen for 2 hours) versus sham control were assessed in a randomized crossover fashion. Heat acutely decreased systolic BP by -19±4 mm Hg (versus 3±4 with sham,
<0.001) owing to decreases in stroke volume (-18±5% versus -4±4%,
=0.013 ) and cardiac output (-15±5% versus -2±4%,
=0.013). In Protocol 2 (proof-of-concept overnight study; n=12), we compared the effects of local heat (38°C applied with a water-perfused heating pad placed under the torso from 10 pm to 6 am) versus placebo pill. Heat decreased nighttime systolic BP (maximal change -28±6 versus -2±6 mm Hg,
<0.001). BP returned to baseline by 8 am. The nocturnal systolic BP decrease correlated with a decrease in urinary volume (
=0.57,
=0.072) and an improvement in the morning upright systolic BP (
=-0.76,
=0.007). Conclusions Local heat therapy effectively lowered overnight BP in patients with autonomic failure and supine hypertension and offers a novel approach to treat this condition. Future studies are needed to assess the long-term safety and efficacy in improving nighttime fluid loss and daytime orthostatic hypotension. Registration URL: https://www.clinicaltrials.gov; Unique identifiers: NCT02417415 and NCT03042988.
Combined cycle power plants (CCPP) are popular in the energy sector for the production of electricity, and are the union of two thermodynamic cycles, corresponding to the steam turbine and the gas ...turbine. This paper presents the application of several machine learning (ML) techniques and the adaptive neuro-fuzzy inference system (ANFIS) to predict the hourly electricity production in a CCPP. The models were developed using 5-fold cross-validation with the collected features of temperature, exhaust pressure, relative humidity, ambient pressure, and electricity production per hour (the target feature). The hyperparameters of the tested models were optimized. The correlation and determination coefficients of the models were higher than 92%, showing a significant performance. The ANFIS (r = 98% e R2 = 95%) model shows the lowest values in the evaluated error metrics, compared to the other ML models. Finally, the results showed the effectiveness of ANFIS in predicting the hourly production of electricity in CCPP.
PDF
