IGF-1 phosphorylates AMPK-alpha subunit in ATM-dependent and LKB1-independent manner

Serine/threonine protein kinase AMP-activated protein kinase (AMPK) is a key metabolic stress-responsive factor that promotes the adaptation of cells to their microenvironment. Elevated concentrations of intracellular AMP, caused by metabolic stress, are known to activate AMPK by phosphorylation of the catalytic subunit. Recently, the tumor suppressor serine/threonine protein kinase LKB1 was identified as an upstream kinases, AMPKKs. In the current study, we found that stimulation with growth factors also caused AMPK-alpha subunit phosphorylation. Interestingly, even an LKB1-nonexpressing cancer cell line, HeLa, exhibited growth factor-stimulated AMPK-alpha subunit phosphorylation, suggesting the presence of an LKB1-independent pathway for AMPK-alpha subunit phosphorylation. In the human pancreatic cancer cell line PANC-1, AMPK-alpha subunit phosphorylation promoted by IGF-I was suppressed by antisense ataxia telangiectasia mutated (ATM) expression. We found that IGF-1 also induced AMPK-alpha subunit phosphorylation in the human normal fibroblast TIG103 cell line, but failed to do so in a human fibroblast AT2-KY cell line lacking ATM. Immunoprecipitates of ATM collected from IGF-1-stimulated cells also caused the phosphorylation of the AMPK-alpha subunit in vitro. IGF-1-stimulated ATM phosphorylation at both threonine and tyrosine residues, and our results demonstrated that the phosphorylation of tyrosine in the ATM molecule is important for AMPK-alpha subunit phosphorylation during IGF-1 signaling. These results suggest that IGF-1 induces AMPK-alpha subunit phosphorylation via an ATM-dependent and LKB1-independent pathway. (C) 2004 Elsevier Inc. All rights reserved.

Hydrogen economy options for Australia

Global concerns over the effects of current carbon dioxide (CO2) emissions have lead to extensive research on the use of hydrogen as a potential energy carrier for a lower emissions society. Hydrogen can be produced from both fossil and renewable energy sources. The hydrogen economy, in which hydrogen will be a carrier of energy from renewable sources, is a long-term development and any increasing demand for hydrogen will probably be covered initially from fossil sources. Technologies for hydrogen generation from renewable energies are being explored, whereas technologies for hydrogen production from fossil fuels have to a certain extent reached maturity. This paper addresses the major hydrogen generation processes and utilisation technology (fuel cells) currently available for the move from a fossil fuelsbased economy to a hydrogen economy. In particular, it illustrates the applicability of different hydrogen sources using Australia as an example.

Hydrogen production and utilisation opportunities for Australia

Worldwide, research and policy momentum is increasing in the move towards a hydrogen economy. Australia is one of the highest per capita users of energy, but relies heavily on fossil fuels to fulfil its energy requirements-thus making it one of the highest per capita polluters. It is also a country rich in natural resources, giving it the full range of options for a hydrogen economy. With the first Australian Hydrogen Study being completed by the end of 2003, there has as yet been little analysis of the options available to this country specifically. This paper reviews the resources, production and utilisation technology available for a hydrogen economy in Australia, and discusses some of the advantages and disadvantages of the different options. It points out that coal, natural gas, biomass and water are the most promising hydrogen sources at this stage, while solid oxide and molten carbonate fuel cells may hold the advantage in terms of current expertise for utilising hydrogen rich gases for stationary power in Australia. (c) 2004 International Association for Hydrogen Energy. Published by Elsevier Ltd. All rights reserved.

Mg-based nanocomposites with high capacity and fast kinetics for hydrogen storage

Magnesium and its alloys have shown a great potential in effective hydrogen storage due to their advantages of high volumetric/ gravimetric hydrogen storage capacity and low cost. However, the use of these materials in fuel cells for automotive applications at the present time is limited by high hydrogenation temperature and sluggish sorption kinetics. This paper presents the recent results of design and development of magnesium-based nanocomposites demonstrating the catalytic effects of carbon nanotubes and transition metals on hydrogen adsorption in these materials. The results are promising for the application of magnesium materials for hydrogen storage, with significantly reduced absorption temperatures and enhanced ab/desorption kinetics. High level Density Functional Theory calculations support the analysis of the hydrogenation mechanisms by revealing the detailed atomic and molecular interactions that underpin the catalytic roles of incorporated carbon and titanium, providing clear guidance for further design and development of such materials with better hydrogen storage properties.

Design of high quality doped CeO2 solid electrolytes with nanohetero structure

Doped ceria (CeO2) compounds are fluorite related oxides which show oxide ionic conductivity higher than yttria-stabilized zirconia in oxidizing atmosphere. As a consequence of this, a considerable interest has been shown in application of these materials for low (400-650 degrees C) temperature operation of solid oxide fuel cells (SOFCs). In this paper, our experimental data about the influence of microstructure at the atomic level on electrochemical properties were reviewed in order to develop high quality doped CeO2 electrolytes in fuel cell applications. Using this data in the present paper, our original idea for a design of nanodomain structure in doped CeO2 electrolytes was suggested. The nanosized powders and dense sintered bodies of M doped CeO2 (M:Sm,Gd,La,Y,Yb, and Dy) compounds were fabricated. Also nanostiructural features in these specimens were introduced for conclusion of relationship between electrolytic properties and domain structure in doped CeO2. It is essential that the electrolytic properties in doped CeO2 solid electrolytes reflect in changes of microstructure even down to the atomic scale. Accordingly, a combined approach of nanostructure fabrication, electrical measurement and structure characterization was required to develop superior quality doped CeO2 electrolytes in the fuel cells.

Hydrogen from coal: Production and utilisation technologies

Error condition detected Although coal may be viewed as a dirty fuel due to its high greenhouse emissions when combusted, a strong case can be made for coal to be a major world source of clean H-2 energy. Apart from the fact that resources of coal will outlast oil and natural gas by centuries, there is a shift towards developing environmentally benign coal technologies, which can lead to high energy conversion efficiencies and low air pollution emissions as compared to conventional coal fired power generation plant. There are currently several world research and industrial development projects in the areas of Integrated Gasification Combined Cycles (IGCC) and Integrated Gasification Fuel Cell (IGFC) systems. In such systems, there is a need to integrate complex unit operations including gasifiers, gas separation and cleaning units, water gas shift reactors, turbines, heat exchangers, steam generators and fuel cells. IGFC systems tested in the USA, Europe and Japan employing gasifiers (Texaco, Lurgi and Eagle) and fuel cells have resulted in energy conversions at efficiency of 47.5% (HHV) which is much higher than the 30-35% efficiency of conventional coal fired power generation. Solid oxide fuel cells (SOFC) and molten carbonate fuel cells (MCFC) are the front runners in energy production from coal gases. These fuel cells can operate at high temperatures and are robust to gas poisoning impurities. IGCC and IGFC technologies are expensive and currently economically uncompetitive as compared to established and mature power generation technology. However, further efficiency and technology improvements coupled with world pressures on limitation of greenhouse gases and other gaseous pollutants could make IGCC/IGFC technically and economically viable for hydrogen production and utilisation in clean and environmentally benign energy systems. (c) 2005 Elsevier B.V. All rights reserved.

Microstructures and electrolytic properties of yttrium-doped ceria electrolytes: Dopant concentration and grain size dependences

The microstructures and electrolytic properties of YxCe1-xO2-x/2 (x = 0.10-0.25) electrolytes with average grain size in the range 90 nm-1.7 mu m were systematically investigated. Through detailed transmission electron microscopy characterization, nanosized domains were observed. The relationship of the domains, the doping level and grain sizes were determined, and their impacts on the electrolytic properties were systematically studied. It was found that the formation of domains has a negative impact on the electrolytic properties, so that electrolytic properties can be adjusted through careful control of domain formation, doping level and grain size. (c) 2006 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.