[en] Highlights: • Bio-oil from liquefaction of wet E. prolifera was as feasible as dry powder. • Adding acid catalysts could improve the flow property of bio-oil. • Alkenes in the bio-oil converted to ketones in the presence of acid catalysts. • Content of 5-methyl furfural increased in the bio-oil obtained with acid catalysts. • Esters were formed in the bio-oil when adding sulfuric acid as a catalyst. - Abstract: Direct liquefaction of macroalgae Enteromorpha prolifera without predrying treatment was performed in a batch reactor. Effects of temperature, reaction time, biomass-to-water ratio and acid catalysts (sulfuric acid and acetic acid) on liquefaction products were investigated. Raw material and liquefaction products were analyzed by elemental analysis, Fourier transform infrared (FT-IR) and gas chromatography–mass spectrometry (GC–MS). Results showed that liquefaction at 290 °C for 20 min with 1:3 biomass-to-water ratio produced the highest bio-oil yield of 28.4 wt%, and high heating value (HHV) was 29.5 MJ/kg. Main components of bio-oil were fatty acids, ketones, alkenes and 5-methyl furfural, and main components of water soluble organics (WSOs) were pyridines, carboxylic acids and glycerol. In the bio-oil obtained with acid catalysts, content of ketones significantly increased while alkenes disappeared. Content of 5-methyl furfural also increased. Flow property of bio-oils was improved in the presence of acid catalysts. Moreover, esters were formed when adding sulfuric acid

[en] A regression analysis is performed to make projections for the Canadian energy production and consumption. These have been increasing and are projected to increase even further in the near future. The primary energy production and consumption are projected to increase by 52% and 34%, respectively, by 2025 over 2004 if business as usual. The amount of fossil energy resources is finite and the extraction, transportation and combustion of fossil fuels cause environmental pollution and climate change. On the other hand, energy plays an important role in the economic and social development of Canada. Canada can develop further from an energy balance point of view, but this alone cannot be sustainable, because of the negative consequences of the major energy use on the environment. Application of energy localization and diversification is a promising solution, but in order to reach that, better energy efficiency and more use of renewable energy are necessary. Instead of non-compulsory policies Canada's policy approach should have more compulsory policies. Only then Canada can be made to develop further in a sustainable manner. (author)

[en] The structure of Fe-M ultrafine particle catalysts was investigated by in situ Moessbauer spectroscopy. Emphasis has particularly been put on the effect of the second metal component. It was found that the incorporation of second metal component hinders the reduction and carburization of iron-containing phase in the presence of H₂ and CO, and the degree of hindrance is in the order of Mg>Mn>Zn due to the interaction between iron and the second metal component. Consequently, the formation of light olefinic products is in the order of Fe-Mg>Fe-Mn>Fe-Zn catalysts consistent with the F-T synthesis performance

[en] The dominance of a single-energy system inevitably leads to excessive burden on, and eventually weakening, a particular aspect of the environment, and can cause environmental fatigue and failure (permanent damage) or even catastrophe if dominated for too long; thus it inevitably poses the health and environmental risk. This is the case for our currently fossil-fuel-based energy systems. In fact, each energy system, including renewables and alternative fuels, has its own unique adverse impact on the environment, as dictated by the second law of thermodynamics. A truly sustainable development may be achieved with the diversification and localization of energy sources and systems if the adverse impact of each energy system is sufficiently small and well within the tolerance limit of the environment. Energy diversification and localization would also provide a security for the energy supply and distribution as well for the energy consumers - a specifically important issue in the wake of blackout (electric power failure) in the Northeastern states to the Midwest of the United States and part of Canada on August 14, 2003. The idea of diversified energy systems for the good of humanity and environment is similar to many analogies in other fields, such as bio-diversity is the best means to prevent the spread and damage of diseases and pests, and diversified investment is the best strategy to guarantee the overall best investment return. It is concluded that the diversification and localization of energy systems is the best future energy systems that would be environmentally compatible, and allow for sustainable development as well as energy security for both supply and distribution to the energy consumers

[en] An inverse scattering transformation method for the generalized coupled nonlinear Schroedinger equations is studied. The appropriate inverse scattering problem is solved. An infinity of conservation laws and one-soliton solutions for two generalized nonlinear Schroedinger equations are obtained

[en] Highlights: • Reviewed the degradation mechanisms for PEM fuel cells. • Summarized the steady-state durability test results and experimental conditions. • Evaluated the in-situ accelerated stress test results and protocols. • Scrutinized the ex-situ accelerated stress test results and experimental techniques. -- Abstract: Durability is one of the most significant technical barriers to successful commercialization of polymer electrolyte membrane (PEM) fuel cells for practical vehicular applications. It is determined by the aging (degradation) and malfunction of various components during the long-term operation. Therefore, understanding the mechanisms of degradation modes in different components is crucial to the development of high-performing and long-lasting PEM fuel cells. In this review article, the critical degradation modes in major cell components, including membranes, catalyst layers, gas diffusion layers, and distribution plates, are comprehensively reviewed and analyzed, and the potential causes are described. Advanced experimental techniques to investigate the PEM fuel cell degradation modes reported in literature include steady-state durability tests and accelerated stress tests (ASTs). The steady-state durability test is straightforward but time-consuming and costly; therefore, ASTs are often applied to accelerate durability testing. For comparable results among different research studies, the experimental protocols and conditions have to be consistent, and the details of these experimental techniques are systematically reviewed in this article. The experimental results with a focus on the degradation modes, degradation rate, and test time of the PEM fuel cells have been reported. Finally, in order to understand the root causes of degradation modes and to develop the mitigation strategies, ex-situ ASTs in literature have been reviewed, including the effects of cyclic temperature, humidity, water wet-dry, freeze-thaw, clamping stress, and vibration operations.

[en] An effective unconditionally stable implementation of the auxiliary differential equation Crank-Nicolson-approximate-decoupling finite-difference time-domain (ADE-CNAD-FDTD) algorithm for 2-D anisotropic magnetized plasma is proposed. The conventional ADE-FDTD method for 1-D anisotropic dispersive media has high efficiency and accuracy. This paper extends this method to 2-D anisotropic magnetized plasma with the CNAD scheme. The proposed formulations not only solves the problem that incorporates both anisotropy and frequency dispersion at the same time, but also eliminates the Courant-Friedrich-Levy (CFL) stability constraint. A numerical example has been carried out to validate the proposed formulations in the 2-D FDTD domain composed of anisotropic magnetized plasma. The results prove that the proposed formulations significantly save time and perform stably with acceptable accuracy. (authors)

[en] This paper presents a comprehensive, consistent and systematic mathematical model for PEM fuel cells that can be used as the general formulation for the simulation and analysis of PEM fuel cells. As an illustration, the model is applied to an isothermal, steady state, two-dimensional PEM fuel cell. Water is assumed to be in either the gas phase or as a liquid phase in the pores of the polymer electrolyte. The model includes the transport of gas in the gas flow channels, electrode backing and catalyst layers; the transport of water and hydronium in the polymer electrolyte of the catalyst and polymer electrolyte layers; and the transport of electrical current in the solid phase. Water and ion transport in the polymer electrolyte was modeled using the generalized Stefan-Maxwell equations, based on non-equilibrium thermodynamics. Model simulations show that the bulk, convective gas velocity facilitates hydrogen transport from the gas flow channels to the anode catalyst layers, but inhibits oxygen transport. While some of the water required by the anode is supplied by the water produced in the cathode, the majority of water must be supplied by the anode gas phase, making operation with fully humidified reactants necessary. The length of the gas flow channel has a significant effect on the current production of the PEM fuel cell, with a longer channel length having a lower performance relative to a shorter channel length. This lower performance is caused by a greater variation in water content within the longer channel length

[en] Highlights: • Investigated the impact of short-side chain (SSC) ionomer in catalyst layers. • Achieved higher Pt utilization and active surface area by using SSC ionomer. • Obtained higher durability of PEM fuel cells via accelerated stress test. • Observed significant impact of SSC ionomer for higher Pt loading cells. • Measured higher degradation of the cell performance for low Pt loading cells. For polymer electrolyte membrane fuel cells (PEMFCs), the importance of durability is widely recognized, but less attention has been paid to the role of ionomers. In this study, the importance of ionomer structure in achieving high PEMFC performance and durability are investigated experimentally for different catalyst-ionomer ratios and catalyst loadings in scaled up cell (45 cm²). The results are compared with a conventional long side chain ionomer (LSC) under the same preparation and testing conditions. Catalyst layers (CLs) fabricated with 25 wt% of short side chain (SSC) ionomer display higher performance than 17 wt% and 30 wt%. A similar trend is also demonstrated when using the LSC ionomer. However, it is found that SSC ionomer is more compatible with CLs than LSC. This compatibility is ascribed to the higher stability of the SSC ionomer. In addition, higher performance, Pt utilization, and active surface area are measured for membrane electrode assemblies (MEAs) prepared with SSC in comparison to LSC under the same ratio. Based on the accelerated stress tests, SSC ionomer has a positive role in improving durability, as the maximum power density after 30,000 cycles decreases by 21% and 48% for MEAs prepared by SSC and LSC, respectively. Moreover, the losses in performance are more than two times greater than when the Pt loading is decreased from 0.5 mg/cm² to 0.125 mg/cm². These results highlight the importance of ionomer structure in cell performance and durability at high and low Pt loadings.

[en] Cultural situation generally played a crucial role on biodegradation mechanism establishment of pollutant. Extensive studies had focused on the optimization of cultivation environment based on in situ conditions. However, there were still few reports on the effects of artificial control on microbial growth and degradation. In this work, the relationship of biomass, situation, and artificial control was explored through the biodegradation of nonylphenols as standard containments by four trains named A. niger, A. terreus SHPP01, A. terreus NIH2624, and T. aff. harzianum from the estuary sediment of Jiaozhou Bay. Various culture conditions covering mineral salt medium, glucose synergistic medium, and carbon rich complex medium had been used to quest the relationship. As a conclusion, different strains usually showed different mechanisms within the same media. The correlation ship between biomass and degradation and removal rate was positive, and the natural medium was usually the best choice for microbial study in situ simulation. Hence, our study provided a valuable reference for the realization of more efficient and rapid biodegradation of pollutants.