Electrolyte effect on the catalytic performance of Ni-based catalysts for direct internal reforming molten carbonate fuel cell

An active and tolerant Ni-based catalyst for methane steam reforming in direct internal reforming molten carbonate fuel cells (DIR-MCFCs) was developed. Deactivation of reforming catalysts by alkali metals from the electrolyte composed of Li₂CO₃ and K₂CO₃ is one of the major obstacles to be overcome in commercialization of DIR-MCFCs. Newly developed Ni/MgSiO₃ and Ni/Mg₂SiO₄ reforming catalysts show activities of ca. 80% methane conversion. Subsequent to electrolyte addition to the catalyst, however, the activity of Ni/Mg₂SiO₄ decreases to ca. 50% of its initial value, whereas Ni/MgSiO₃ catalyst retains its initial activity. Results obtained from temperature-programmed reduction and X-ray photoelectron spectroscopy identify unreduced Ni³⁺ as a decisive factor in keeping catalytic activity from the electrolyte.     

Fuzzy-neuro LVQ and its comparison with fuzzy algorithm LVQ in artificial odor discrimination system

The human sensory test is often used for obtaining the sensory quantities of odors, however, the fluctuation of results due to the expert's condition can cause discrepancies among panelists. Authors have studied the artificial odor discrimination system using a quartz resonator sensor and a back-propagation neural network as the recognition system, however, the unknown category of odor is always recognized as the known category of odor. In this paper, a kind of fuzzy algorithm for learning vector quantization (LVQ) is developed and used as a pattern classifier. In this type of fuzzy LVQ, the neuron activation is derived through fuzziness of the input data, so that the neural system could deal with the statistics of the measurement error directly. During learning, the similarity between the training vector and the reference vectors are calculated, and the winning reference vector is updated by shifting the central position of the fuzzy reference vector toward or away from the input vector, and by modifying its fuzziness. Two types of fuzziness modifications are used, i.e., a constant modification factor and a variable modification factor. This type of fuzzy-neuro (FN) LVQ is different in nature from fuzzy algorithm (FA) LVQ, and in this paper, the performance of FNLVQ network is compared with that of FALVQ in an artificial odor recognition system. Experimental results show that both FALVQ and FNLVQ could provide high recognition probability in determining various known categories of odors, however, the FNLVQ neural system has the ability to recognize the unknown category of odor that could not be recognized by the FALVQ neural system.     

Synthesis and Surface-Active Properties of Uronic Amide Derivatives,Surfactants from Renewable Organic Raw Materials

Short chemical syntheses were developed to produce a new set of surfactants from uronic acids derived from widely available raw materials. Three different strategies were used to synthesize uronic amide derivatives, the structures of which were totally characterized by spectrometric methods (IR, MS, ¹H-RMN and ¹³C-RMN). The best one, using an acid chloride as the synthetic intermediate, furnished the expected amides as a mixture of anomers in 46–58% global yield. Surface-active properties (CMC, γ_cmc, Γ_max, A _min) of homologous series of uronic acid N-alkylamides from C8 to C18 were also assessed. In general, these sugar-based surfactants exhibited good surface-activities, and appeared as valuable nonionic surfactants compared to octylphenol 9–10 ethylene oxide condensate, the most well-known nonionic surfactant. Increasing the alkyl chain length influenced the CMC values for both glucuronic and galacturonic N-alkylamide derivatives. The galacturonic N-alkylamides decreased γ_cmc at slower values than their counterpart’s glucuronic N-alkylamides.     

Foaming properties of surfactin,a lipopeptide biosurfactant fromBacillus subtilis

Foaming properties of surfactin were investigated and compared to those of sodium dodecyl sulfate (SDS) and bovine serum albumin (BSA). Foams were formed by a bubbling technique. Evolution of the foam volume and the liquid in the foam was monitored with optical and conductimetric methods to characterize foam formation and stability. Excellent foaming properties of surfactin were shown by its higher ability to form and stabilize the foam at a concentration as low as 0.05 mg/mL, in comparison with SDS and BSA. Surfactin produced a foam with intermediate maximum density and stabilized the liquid in foam, as well as BSA.     

An integrated approach to Deacon chemistry on RuO2-based catalysts

Rationally designed RuO₂-based Deacon catalysts can contribute to massive energy saving compared to the current electrolysis process in chemically recycling HCl to produce molecular chlorine. Here, we report on our integrated approach between state-of-the-art experiments and calculations. The aim is to understand industrial Deacon catalyst in its realistic surface state and to derive mechanistic insights into this sustainable reaction. We show that the practically relevant RuO₂/SnO₂ consists of two major RuO₂ morphologies, namely 2–4 nm-sized particles and 1–3-ML-thick epitaxial RuO₂ films attached to the SnO₂ support particles. A large fraction of the small nanoparticles expose {1 1 0} and {1 0 1} facets, whereas the film grows with the same orientations, due to the preferential surface orientation of the rutile-type support. Steady-state Deacon kinetics indicate a medium-to-strong positive effect of the partial pressures of reactants and deep inhibition by both water and chlorine products. Temporal Analysis of Products and in situ Prompt Gamma Activation Analysis strongly suggest a Langmuir–Hinshelwood mechanism and that adsorbed Cl poisons the surface. Under relevant operation conditions, the reactivity is proportional to the coverage of a specific atomic oxygen species. On the extensively chlorinated surface that can be described as surface oxy-chloride, oxygen activation is the rate-determining step. DFT-based micro-kinetic modeling reproduced all experimental observations and additionally suggested that the reaction is structure sensitive. Out of the investigated models, the 2 ML RuO₂ film-covered SnO₂ gives rise to significantly higher reactivity than the (1 0 1) surface, whereas the 1 ML film seems to be inactive.     

Effect of ageing on different egg yolk fractions on surface properties at the air–water interface

The aim of this study was to evaluate the impact of egg ageing on the surface properties of whole and fractionated yolk at the air–water interface. Eggs were stored at 4°C for 24 h, 1 week and 3 weeks after laying. A laboratory scale fractionation process was then applied at each ageing time. Egg yolk was separated into two fractions, plasma composed of low‐density lipoproteins (LDLs) and livetins, and granules formed by high‐density lipoproteins (HDLs), phosvitins and LDLg (g = granule). Moreover, recombined plasma and granules fractions were investigated to highlight a potential synergic effect on surface properties. Results have shown the main contribution of LDLs on surface properties of yolk and an improvement of granules surface properties when they are disrupted. Moreover, ageing affected surface properties differently depending on the considered fractions. Broken LDLs and disrupted granules could explain this observed behaviour. Recombined fractions showed different compression isotherms at the air–water interface than whole yolk.     

Circuit Models and Simulation Analysis of Electromyographic Signal Sources?I: The Impedance of EMG Electrodes

The impedance of surface and intramuscular biopotential electrodes was measured during rest and muscle contraction in humans. A frequency-dependent parallel RC circuit model of the skin-electrode interface that captures the dependence of this impedance on the size and geometry of electrode placement was developed and its components were estimated. The model could explain between 86-97 percent of the variations in impedance (Z), 72-92 percent of the variations in resistance (R), and 34-93 percent of the variations in capacitance (C). The impedance and resistance of these electrodes decrease by about tenfold for a 20-fold increase in frequency, while the capacitance decreases by about twofold for the same change in frequency (f). Thus, the overall FRC factor of this parallel RC circuit model remains nearly unchanged over the range of frequencies studied (50-2000 Hz). A significant difference was found between the impedances of the electrodes comprising the differential electrode pair. This imbalance in impedance was between 8-14 percent for surface electrodes and 6-19 percent for wire electrodes. These data provide essential design criteria for the development and simulation of a system for the measurement of electromyographic activity.     

Supercritical CO2-Assisted SiOx/Carbon Multi-Layer Coating on Si Anode for Lithium-Ion Batteries

Supercritical CO₂ (SCCO₂), characterized by gas-like diffusivity, low surface tension, and excellent mass transfer properties, is applied to create a SiO_x/carbon multi-layer coating on Si particles. Interaction of SCCO₂ with Si produces a continuous SiO_x layer, which can buffer Si volume change during lithiation/delithiation. In addition, a conformal carbon film is deposited around the Si@SiO_x core. Compared to the carbon film produced via a conventional wet-chemical method, the SCCO₂-deposited carbon has significantly fewer oxygen-containing functional groups and thus higher electronic conductivity. Three types of carbon precursors, namely, glucose, sucrose, and citric acid, in the SCCO₂ syntheses are compared. An eco-friendly, cost-effective, and scalable SCCO₂ process is thus developed for the single-step production of a unique Si@SiO_x@C anode for Li-ion batteries. The sample prepared using the glucose precursor shows the highest tap density, the lowest charge transfer resistance, and the best Li⁺ transport kinetics among the electrodes, resulting in a high specific capacity of 918 mAh g⁻¹ at 5 A g⁻¹. After 300 charge–discharge cycles, the electrode retains its integrity and the accumulation of the solid electrolyte interphase is low. The great potential of the proposed SCCO₂ synthesis and composite anode for Li-ion battery applications is demonstrated.     

The effect of Al addition on the prevention of Ni sintering in bio-ethanol steam reforming for molten carbonate fuel cells

This paper investigates the effect of modifying an Ni catalyst on the prevention of sintering of the catalyst at high temperatures, without causing a reduction in catalytic activity. The Ni catalyst was modified by adding Al through a solid–gas–solid reaction at a low temperature to produce an Ni–Al solid solution. This process allows for low-cost production of the modified catalyst. An activity test of the catalysts was carried out at 650 °C and 1 atm to simulate direct internal reforming of a molten carbonate fuel cell (MCFC). Experimental results showed consistent activity of the Al-modified catalyst, even after aging under severe conditions (900 °C) to simulate accelerated sintering. TEM data did not show any significant physical changes even after aging. Addition of Al appeared to have successfully prevented Ni from sintering without reducing its catalytic activity in reforming bio-ethanol. In addition, an Ni–Al/MgO catalyst, integrated into the anode of an MCFC, was successfully tested for over 2000 h without any significant performance degradation.