A role for the Parkinson's disease kinase LRRK2 in endo-lysosomal and cytoskeletal function

Parkinson's disease (PD) is a progressive neurodegenerative disorder affecting millions of people globally. Like other age-related conditions, inheritance of genetic variations contributes to PD pathogenesis. Mutations in leucine-rich repeat kinase 2 (LRRK2) are linked with familial forms of late-onset PD. Importantly, the LRRK2 locus has been identified by genome-wide association studies to contribute to risk of sporadic disease. These observations suggest that the study of LRRK2 cell biological function and dysfunction might shed light on the pathogenesis of PD. LRRK2 is a large multidomain cytosolic protein reported to play a role in a variety of cellular functions such as cytoskeletal dynamics, vesicular trafficking and autophagy. Mouse models deficient of LRRK2 or harbouring the pathogenic human G2019S mutation do not show typical PD brain pathology. However, reported phenotypic kidney pathology in LRRK2 knockout mice provides a rationale to investigate LRRK2 knockout and G2019S knockin kidneys to further elucidate the biological role of LRRK2. Using an unbiased quantitative proteomic approach, significant alterations in protein levels associated with cytoskeletal, lysosomal, vesicular trafficking and control of protein translation were observed in Lrrk2 knockout but not G2019S knockin tissue. Lysosomal protein accumulation and changes in expression of a subset of cytoskeletal proteins were validated using orthogonal techniques in independent cohorts of mice across several age time points. Very few protein changes were observed in brain or varied in opposite directions in knockout versus knockin mice. A role for LRRK2 in the endo-lysosomal pathway was further confirmed in primary kidney cells from LRRK2 knockout mice. Overall, these results imply LRRK2 co-ordinated responses in protein trafficking and cytoskeletal dynamics, and argue against a simple dominant negative role for the G2019S mutation

The role of SIRT3 in mitochondrial homeostasis and in cell survival

SIRT3 is one of the most studied sirtuins and is involved in the regulation of many processes. It localizes in the mitochondria, one of the most important organelle of the cell. Indeed, mitochondria are responsible, among other things, for the energetic state of the cell and play a fundamental role in the cellular response toward stress condition. Several works point the attention on the role of SIRT3 in mediating cellular resistance toward various forms of stress by maintaining genomic stability and mitochondrial integrity. Aim of the present study was to clarify the role of SIRT3 in the cellular response toward stress condition. In particular the role of SIRT3 in the presence of hypoxic and staurosporine (STS)-mediated stress was analyzed. Moreover the molecular mechanism by which this sirtuin confers resistance to cell death was investigated

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Regeneration Section of CO2 Capture Plant by MEA Scrubbing with a Rate-Based Model

CO2 capture from exhaust gas of power plants, natural gas and refinery gas can be successfully achieved by chemical absorption with alkanolamines. CO2 capture from exhaust gas is often obtained by absorption with monoethanolamine (MEA) which is the most frequently used solvent for this purpose. Thermodynamics, kinetics and mass transfer influence the chemical absorption process. Acidic gases and amines are weak electrolytes, which partially dissociate in the aqueous phase: the high non-ideality of the liquid phase must be properly taken into account, by employing a γ/φ method. Kinetics and mass transfer can be described using two different approaches: the “equilibrium-based stage efficiency” model or the “rate-based” one. ASPEN Plus® uses the rate-based model, but the prediction of mass transfer coefficients is based on the film theory by Lewis and Whitman, while other theories can more conveniently be used, i.e. the Eddy Diffusivity theory. Since ASPEN Plus® simulator is suitable to be user customized, it has been chosen as framework for the model proposed in this work, that was validated by comparing simulation results with experimental data of a pilot plant for the purification of exhaust gas from power plant by means of MEA washing

Regeneration section of CO2 capture plant by MEA scrubbing with a rate-based model

CO2 capture from exhaust gas of power plants, natural gas and refinery gas can be successfully achieved by chemical absorption with alkanolamines. CO2 capture from exhaust gas is often obtained by absorption with monoethanolamine (MEA) which is the most frequently used solvent for this purpose. Our paper focuses on the regeneration section, where the amine solution is separated from the absorbed CO2 and recirculated to the absorber. Since regeneration is obtained in a stripper or a distillation column, it is the most energy demanding unit of the plant, so a careful modeling is required. Thermodynamics, kinetics and mass transfer influence the chemical absorption process. Acidic gases and amines are weak electrolytes, which partially dissociate in the aqueous phase: the high non-ideality of the liquid phase must be properly taken into account, by employing a γ/φ method. Kinetics and mass transfer can be described using two different approaches: the “equilibrium-based stage efficiency” model or the “rate-based” one. ASPEN Plus® uses the rate-based model, but the prediction of mass transfer coefficients is based on the film theory by Lewis and Whitman, while other theories can more conveniently be used, i.e. the Eddy Diffusivity theory. Since ASPEN Plus® simulator is suitable to be user customized, it has been chosen as framework for the model proposed in this work, that was validated by comparing simulation results with experimental data of a pilot plant for the purification of exhaust gas from power plant

Sustainable combined production of hydrogen and energy from biomass in malaysia

This work relates to a comparison between process solutions for the production of H2 and the coproduction of H2 and energy by means of a zero emission biomass integrated gasification and a combined cycle (BIGCC) power plant. The energy production is 10 MWe, in agreement with the Small Renewable Energy Power Plant (SREP) Program, promoted by the Government of Malaysia. H2 is obtained by supercritical water gasification (SCWG), a technology of interest for the processing of biomass with high moisture content. An economic analysis has been carried out in order to demonstrate the feasibility of the process solutions and to compare their convenience. The feedstock is 280,000 t/y of Empty Fruit Bunch (EFB), a biomass obtained in the Palm Oil Industry. The location of the site is Teluk Intak District in the State of Perak (Malaysia). The processes are designed with Aspen Plus® V7.2. The aim of this work is to develop detailed process flow diagrams for the supercritical water gasification technology in order to study and compare the convenience and the sustainability of different scenarios that can be adopted in an industrial context. The processes have been developed to reach zero emissions and zero wastes. CO2 and solid residuals are recycled inside the palm oil lifecycle. A cost analysis has been performed to find out the convenience of the proposed solutions

Energy analysis of different municipal sewage sludge-derived biogas upgrading techniques

Biomass-derived energy sources are rising their importance since both public opinion and legislation are currently calling for a sustainable development. Biogas is an energy source which can come from municipal sewage sludge digestion thus coupling the advantages of being a renewable energy source and of allowing a smart waste reutilization. In order to fully exploit the biogas potential as vehicle fuel or natural gas substitute, biogas itself must be treated in order to obtain biomethane. Biogas upgrading, i.e., the treatment for CO2 removal, can be performed by several techniques, each one characterised by a different energy demand. Since no clear guidelines are given in literature for choosing among different biogas upgrading processes, this work presents a quantitative analysis, from an energy view point, of water scrubbing, MEA (monoethanolamine) scrubbing, and MDEA (methyldiethanolamine) scrubbing when applied to obtain biomethane from municipal sewage sludge-derived biogas. Heat and electrical power consumptions of each of the above mentioned processes have been obtained by means of process simulation with commercial packages (such as Aspen Plus®). The aim of the work is the energetic comparison among these different techniques. Such a comparison can help in assessing the impact of the biogas purification step on the energy balance of the whole biomethane production process

Refrigeration cycles in low-temperature distillation processes for the purification of natural gas

The increasing energy demand has made low-quality natural gas reserves worthy of consideration for exploitation. As a consequence, industries have developed new process solutions in order to exploit these gas reservoirs in a profitable way. Most of these solutions are natural gas purification processes by distillation at low-temperature, involving or not solid CO2 formation. Due to the low-temperatures reached in this type of processes, the choice of the appropriate refrigeration cycle becomes of paramount importance for limiting their energy consumptions and, thus, their operating costs. The aim of this work is to compare the performances of different types of refrigeration cycles using the coefficient of performance (COP) as discriminating factor. Several compounds (such as nitrogen, light hydrocarbons and ethylene) and their mixtures have been considered as working fluids and both non-cascade and cascade systems have been taken into account. Simulations by means of Aspen Hysys® V7.3 have led to conclude that the propane-ethylene cascade refrigeration cycle allows to attain the best performances