High-Stable Mesoporous Ni-Ce/Clay Catalysts for Syngas Production

Abstract  

A mesoporous-type catalytic support was synthesized through the modification of a smectite with polyvinyl alcohol (PVA) and microwaves. Texture and micro-morphology of the support was determined. Several techniques were employed in order to describe the chemical environment of active species on the surface. Ni⁰ particle sizes were dependent on the structural site of reducible species. High stable Ni-Ce catalysts (calcined at 800 °C) were evaluated in the CO₂ reforming of methane reaction at 700 °C (WHSV = 96 L g⁻¹ h⁻¹, without dilution gas and pre-reduction). The catalysts have presented CH₄ conversions between 40 and 65%, CO₂ conversion between 35 and 65% and H₂/CO ratios between 0.2 and 0.4.     

Characterisation and modelling of the elastic properties of poly(lactic acid) nanofibre scaffolds

The aim of this study is to predict the elastic response of poly(lactic acid) (PLA) electrospun nanofibre scaffolds through mathematical models based on homogenisation and the differential replacement method (DRM). These models principally seek to determine and analyse the effects of the internal morphology of the nanofibres on the effective Young’s modulus of polymer nanofibre scaffolds. The microstructure of the nanofibres was first characterised by SEM, XRD, DSC, AFM, and TEM techniques. From this characterisation, strong evidence of a hierarchical core–shell structure was found. With the experimental data, it was possible to design and validate better models than those currently used. In addition, the effects of the electrospinning parameters, such as take-up velocity and thermal treatment, were analysed and correlated with the morphology and the elastic properties of the nanofibres and their scaffolds. To validate the models’ results, we conducted a series of uniaxial tensile tests on the PLA nanofibre scaffolds. Using the data from the nanofibre measurements, the homogenisation approximations and the model based on the DRM predicted an effective Young’s modulus of 667 and 835 MPa, respectively. The predicted data were in excellent agreement with the experimental results (685–880 MPa). These models will be useful in understanding and evaluating the structure–property relationships of oriented nanofibre scaffolds for medical or biological applications.     

Low‐molecular‐weight glycerol esters as plasticizers for poly(vinyl chloride)

Phthalates are the most important plasticizers used in the polymer industry. However, their fossil origin and the results of recent tests showing their potential negative effect on human health have encouraged the polymer industry to turn toward non‐phthalate plasticizers. At the same time, the biodiesel industry produces a surplus of glycerol, thus leading the scientific community to seek new applications for this substance. This paper presents the performance of eight esters derived from glycerol as plasticizers for poly(vinyl chloride), including tests to evaluate their compatibility. Results show that glycerol esters obtained from propanoic, butanoic, isobutanoic, isopentanoic, and benzoic acids, while volatile, can be used as poly(vinyl chloride) plasticizers in certain applications. J. VINYL ADDIT. TECHNOL., 20:65–71, 2014. © 2014 Society of Plastics Engineers     

Enhanced LSCF oxygen deficiency through hydrothermal synthesis

High-performance perovskites are promising materials for diverse renewable energy technologies. Besides design characteristics, the devices performance depends on the material synthesis, since the processes occurring during synthesis may produce different structures and properties. In this work, the perovskite La_0.1Sr_0.9Co_0.9Fe_0.1O_3-δ (LSCF1991) was synthesized by different methods, and the phase composition and oxygen deficiency were assessed and discussed. We show that it is possible to increase oxygen deficiency by promoting oxygen release during crystallization within hydrothermal synthesis, producing a remarkable improvement of ?δ ~0.2 in comparison with the citrate method. The single phase LSCF1991 powder was characterized, shaped by different routes and sintered to demonstrate the stability and suitability to manufacture electrochemical devices.     

Comparative Study of Starch Fibers Obtained by Electro-spinning of Indigenous,Commercial and Cationic Potato Starch

ABSTRACT

By using the electro-spinning process on natural polymers, it is possible to obtain biodegradable membranes with potential applications in filters and scaffolds for tissue engineering. In this study, a comparison was made between the respective chemical, physical and thermal properties of the fibers from two sources of starch: One derived from a local, indigenous variety of potato (Diacol Capiro), native to the Boyacá region of Colombia (from here on referred to as “local starch”); the other, commercially available starch. A cationization of fibers was also carried out on the two starches. Chemical, physical and thermal properties were analyzed by Fourier transform infrared (FTIR), scanning electron microscopy (SEM), X-ray diffraction (DRX), thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The results showed the fibers were cationized with a highly amorphous state, with a heat resistance of 300°C from physicochemical changes generated in the fibers.     

Interpenetrating polymers supported on microporous polypropylene membranes for the transport of chromium ions

Modifying polypropylene membranes with interpenetrating polymer networks (IPNs) through the incorporation of poly(glycidyl methacrylate-N-methyl-D-glucamine) (P(GMA-NMG)) was performed by in situ synthesis via radical polymerization.The surface of the polypropylene membrane was activated by hydrophilic grafted polyelectrolyte,and then,pressure injection was used for the impregnation of the reactive solution in the membrane.Two types of pore-filled membranes were synthesized,chelating interpenetrating homopolymer networks of P(GMA-NMG),and chelating-ion exchange interpenetrating polymer networks (e.g.,P(GMA-NMG)/P(AA),P(GMA-NMG)/P(AMPSA),and P(GMA-NMG)/P(ClVBTA)).After their synthesis,the modified polypropylene membranes were characterized using techniques such as the electrokinetic potential,SEM,FT-IR,and Donnan dialysis to corroborate the chromium ion transport.The P(GMA-NMG) and complex network membranes exhibited a hydrophilic character with a water-uptake capacity between 20％ and 35％ and a percentage of modification between 4.0％ and 7.0％ in comparison with the behavior of the unmodified polypropylene membrane.Hexavalent chromium ions were efficiently transported from the food chamber at pH 9.0 when the 65.2％ MTA1 P(ClVBTA) homopolymer IPN membrane and 48.5％ MTAG P(GMA-NMG)/P(ClVBTA) IPN membrane were used.Similarly,hexavalent chromium ions were removed from the food chamber at pH 3.0 when MTAG (63.30％) and MTA1 (35.68％) were used in 1 mol·L-1 NaCl solution as the extraction reagent.     

Cross‐cultural comparisons between Korean and U.S. adults with respect to texture perception and acceptance of cooked milled rice

This study aimed to determine whether texture perception and acceptance of cooked rice could differ with cultural background, especially between Korean and American participants. Participants evaluated eight cooked rice samples with respect to intensities of textural attributes such as visual stickiness, hardness, stickiness and chewiness. Participants also rated the acceptability of and familiarity with those samples. Results showed that Americans gave higher ratings to cooked rice samples with respect to visual stickiness, stickiness and chewiness, while Koreans gave higher ratings to hardness than their counterpart. For Americans, chewiness was considered as a negative driver; whereas for Koreans, visual stickiness and stickiness were identified as positive drivers of overall liking for cooked rice samples. Moreover, a familiarity level of cooked rice samples was a pronounced positive driver of liking for both American and Korean participants. In conclusion, our findings provide empirical evidence that cultural background influences texture perception and liking of cooked rice.     

Polypropylene membranes modified with interpenetrating polymer networks for the removal of chromium ions

Polypropylene (PP) membranes incorporating poly[(ar‐vinylbenzyl) trimethylammonium chloride] P(ClVBTA), and poly[sodium (styrene sulfonate)] P(SSNa) were modified via an “in situ” radical polymerization synthesis. Two methods were used for impregnation of the reactive solution: pressure injection and plasma superficial activation with argon gas. The following conditions were varied: the monomer concentrations, number of injections, and cross‐linked concentration. The modified polypropylene membranes were then characterized using scanning electron microscopy/energy dispersive X‐ray spectroscopy, Fourier transform‐infrared spectroscopy, electrokinetic potential, and Donnan dialysis for the chromium ions transport. The modified membranes exhibited a hydrophilic character with a water uptake capacity between 15% and 20% and a percent modification between 2.5% and 4.0%. This was compared with the results of an unmodified polypropylene membrane as the blank and the mentioned polypropylene membrane has not the capacity to uptake water because this kind of material is highly hydrophobic. Hexavalent chromium ions were efficiently transported by the modified membranes containing P(ClVBTA) via a plasma method and it achieved 59.2% extraction at pH 9.0 using a 1‐mol L^?1 NaCl extraction agent. Therefore, unmodified polypropylene membrane shows an extraction percentage close to 10% from the hexavalent chromium ions at pH 9.0. In the same way, the trivalent chromium transport using membranes modified with P(SSNa) achieved 49.0% extraction at pH 2.0 using 1 × 10^?1 mol L^?1 HNO₃ and 1 mol L^?1 NaCl as the extraction agents. Moreover, the unmodified polypropylene membrane reached a value close to 10% from the trivalent chromium ions using 1 × 10^?1 mol L^?1 HNO₃ and 1 mol L^?1 NaCl. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41953.     

Volume-aware positioning in the context of a marine port terminal

The rapid proliferation of mobile computing devices and local wireless networks over the past few years has promoted a continuously growing interest in location-aware systems and applications. The main problem with existing positioning techniques is that they are designed to position dimensionless objects. Such an assumption may lead to practical inconsistencies, as it results in neglecting the effects of the volume of an object, its physical characteristics, and its spatial arrangement on signal propagation. In this paper, we consider the problem of positioning cargo containers in a marine port terminal, where such characteristics can be finely estimated. Based on the signal propagation map of a container yard, we propose VAPS, a volume-aware positioning system that takes advantage of the waveguide effect generated by the containers. Although VAPS is specific to the marine port scenario, its design principles can be extended and adapted to other situations. VAPS maps discrete RSSI levels into hop-counts and relies on realistic propagation models to obtain near-perfect positioning at a very low control overhead. Our extensive evaluations show how to set the parameters required in the VAPS algorithm. The results demonstrate that, in scenarios where the assumptions made by traditional approaches fail, the considerations of VAPS make the difference.