102 research outputs found
Structure-activity relationship study of the plant-derived decapeptide OSIP108 inhibiting Candida albicans biofilm formation
We performed a structure-activity relationship study of the antibiofilm plant-derived decapeptide OSIP108. Introduction of positively charged amino acids R, H, and K resulted in an up-to-5-fold-increased antibiofilm activity against Candida albicans compared to native OSIP108, whereas replacement of R9 resulted in complete abolishment of its antibiofilm activity. By combining the most promising amino acid substitutions, we found that the double-substituted OSIP108 analogue Q6R/G7K had an 8-fold-increased antibiofilm activity
The plant-derived decapeptide OSIP108 interferes with Candida albicans biofilm formation without affecting cell viability
We previously identified a decapeptide from the model plant Arabidopsis thaliana, OSIP108, which is induced upon fungal pathogen infection. In this study, we demonstrated that OSIP108 interferes with biofilm formation of the fungal pathogen Candida albicans without affecting the viability or growth of C. albicans cells. OSIP108 displayed no cytotoxicity against various human cell lines. Furthermore, OSIP108 enhanced the activity of the antifungal agents amphotericin B and caspofungin in vitro and in vivo in a Caenorhabditis elegans-C. albicans biofilm infection model. These data point to the potential use of OSIP108 in combination therapy with conventional antifungal agents. In a first attempt to unravel its mode of action, we screened a library of 137 homozygous C. albicans mutants, affected in genes encoding cell wall proteins or transcription factors important for biofilm formation, for altered OSIP108 sensitivity. We identified 9 OSIP108-tolerant C. albicans mutants that were defective in either components important for cell wall integrity or the yeast-to-hypha transition. In line with these findings, we demonstrated that OSIP108 activates the C. albicans cell wall integrity pathway and that its antibiofilm activity can be blocked by compounds inhibiting the yeast-to-hypha transition. Furthermore, we found that OSIP108 is predominantly localized at the C. albicans cell surface. These data point to interference of OSIP108 with cell wall-related processes of C. albicans, resulting in impaired biofilm formation
Syngas Production, Storage, Compression and Use in Gas Turbines
This chapter analyses syngas production through pyrolysis and gasification, its compression and its use in gas turbines. Syngas compression can be performed during or after thermal treatment processes. Important points are discussed related to syngas ignition, syngas explosion limit at high temperatures and high pressures and syngas combustion kinetics. Kinetic aspects influence ignition and final emissions which are obtained at the completion of the combustion process. The chapter is organized into four subsections, dealing with (1) innovative syngas production plants, (2) syngas compressors and compression process, (3) syngas ignition in both heterogeneous and homogeneous systems and (4) syngas combustion kinetics and experimental methods. Particular attention is given to ignition regions that affect the kinetics, namely systems that operate at temperatures higher than 1000 K can have strong ignition, whereas those operating at lower temperatures have weak ignition. Keywords: Pyrogas Pyrolysis Ignition Syngas Compression GasificationacceptedVersio
Steam Injection Experiments in a Microturbine - a Thermodynamic Performance Analysis
This paper reports on a series of steam injection experiments on a Turbec T100 microturbine.Combined Heat and Power (CHP) systems, such as the considered T100 microturbine, use onesingle primary fuel to simultaneously produce electric and thermal power. In doing so, theyrealize significant energy savings when compared to conventional schemes of separatedproduction. However, a reduction in the demand for heat (like e.g. in summertime) will forcethis type of units to shutdown. This significantly reduces the amount of operating hours and hasa severe negative impact on the net present value of such CHP investment projects.The aim of this paper is to investigate and demonstrate the effects of steam injection in thecompressor outlet of a microturbine operating under reduced heat demand conditions, this tokeep the unit running. The necessary steam can be auto-raised with heat available in the turbineexhaust downstream of the recuperator. Such an injection will keep the unit running and thusavoid a forced shutdown. Furthermore it is expected that the electric efficiency will rise andthat the power production will become more economically viable as a result of the increase inoperating hours.This paper reports on the influence of steam injection on the electrical efficiency and shaftspeed of a T100 unit. ASPEN® simulations of the behaviour of the CHP unit are also presented.These simulations predicted a 2.2% rise in electric efficiency at nominal electrical output when5% of the mass flow rate of air is replaced by steam.The steam injection experiments resulted in stable runs of the unit, a predicted reduction inshaft speed and increased electrical efficiency. Validation of the ASPEN® simulations againstthe experimental data revealed the necessity for a more accurate determination of the air massflow rate and more precise compressor characteristics.info:eu-repo/semantics/publishe
Effect of Syngas Moisture Content on the Emissions of Micro-Gas Turbine Fueled with Syngas/LPG in Dual Fuel Mode
Syngas produced by gasification has a potential to be one of the fueling solutions for gas turbines in the future. In addition to the combustible constituents and inert gases, syngas derived by gasification contains a considerable amount of water vapor which effect on syngas combustion behaviour. In this work, a micro-gas turbine with a thermal capacity of 50 kW was simulated using ASPEN Plus. The micro gas turbine system emissions were characterized using dry syngas fuels with a different composition, syngas 1 (10.53% H2, 24.94% CO, 2.03% CH4, 12.80% CO2, and 49.70% N2) and syngas 2 (21.62% H2, 32.48% CO, 3.72% CH4, 19.69% CO2, and 22.49% N2) mixed with LPG in a dual fueling mode. The effect of syngas moisture content was then studied by testing the system with moist syngas/LPG with a moisture content ranging from 0 to 20% by volume. The study demonstrates that the syngas moisture content has high influence on nitrogen oxides and carbon monoxide emissions. It’s found that for 5% syngas moisture content, the NOx emission were reduced by 75.5% and 83% for Syngas 1 and Syngas 2 respectively. On carbon monoxide emissions and for same moisture content ratio, the reduction was found to be 43% and 57% for syngas1 and syngas 2 respectively
Detailed study of the impact of co-utilization of biomass in a natural gas combined cycle power plant through perturbation analysis
Co-utilization of fossil fuels and biomass is a successful way to make efficient use of biomass for power production. When replacing only a limited amount of fossil fuel by biomass, measurements of net output power and input fuel rates will however not suffice to accurately determine the marginal efficiency of the newly introduced alternative fuel. The present paper therefore proposes a technique to determine the marginal biomass efficiency with more accuracy. The process simulation model for co-utilization of natural gas and a small perturbing fraction of biomass in an existing combined cycle plant (500Ă‚Â MWth Drogenbos, Belgium) is taken as case study. In this particular plant, biomass is introduced into the cycle as fuel for a primary steam reforming process of the input natural gas. This paper proposes a perturbation analysis that has been developed to allow for an accurate assessment of the marginal efficiency of biomass by using only accurately measurable variables. To achieve this, effects of co-utilization were studied in each component of the gas turbine down to its steam bottom cycle to identify the components most affected by the limited perturbing amount of biomass. The procedure is validated through process simulation, where accurate marginal efficiencies can be compared with the efficiency obtained from the perturbation analysis. A full off-design simulation is required to achieve this result. Through the use of process simulation, the accuracy of the mathematical model could be verified for each formula and each assumption. Compared to process simulation data, the model was found to accurately predict marginal efficiencies of the introduced biomass for biomass shares as low as 0.1%.Energy Co-utilization Biomass Perturbation analysis Steam reforming
Water injection in a micro gas turbine – Assessment of the performance using a black box method
Microturbines offer new perspectives in small-scale heat and power production however their profitability depends strongly on the yearly amount of running hours. The non-continuous heat demand often leads to a reduction in running hours. This paper proposes an alternative by recuperating the lost thermal power through the injection of heated water in the micro Gas Turbine (mGT). Water injection is considered a successful way to increase power and efficiency in industrial gas turbines and similar effects are expected for microturbines. This paper reports on a series of simulations of water injection performed on a Turbec T100 mGT. The goal of this study was to investigate the potential of water injection in the mGT cycle using an adiabatic black box method in the Aspen® process simulation tool. Past experiments with steam injection on the T100 demonstrated the potential of introducing steam/water in the microturbine cycle.Calculations revealed that the key parameters for maximum heat recuperation are stack and pinch temperature. Simulations showed that most of the exhaust heat can be recovered through injection of heated water after the compressor, resulting in an 18% decrease in fuel consumption and an absolute increase in electrical efficiency of 7%.info:eu-repo/semantics/publishe
Steam injection experiments in a microturbine – A thermodynamic performance analysis
This paper reports on a series of steam injection experiments on a Turbec T100 microturbine. Combined Heat and Power (CHP) systems, such as the considered T100 microturbine, use one single primary fuel to simultaneously produce electric and thermal power. In doing so, they realize significant energy savings compared to conventional schemes of separated production. However, a reduction in the demand for heat (e.g. in summertime) will force this type of units to shutdown. This significantly reduces the amount of operating hours and has a severe negative impact on the net present value of such CHP investment projects.The aim of this paper is to investigate and demonstrate the effects of steam injection in the compressor outlet of a microturbine operating under reduced heat demand conditions, in order to keep the unit running. The necessary steam can be auto-raised with heat available in the turbine exhaust downstream of the recuperator. Such an injection will keep the unit running and thus avoid a forced shutdown. Furthermore, it is expected that the electric efficiency will rise and that the power production will become more economically viable as a result of the increasing operating hours.This paper reports on the influence of steam injection on the electrical efficiency and shaft speed of a T100 unit. ASPEN® simulations of the behavior of the CHP unit are also presented. These simulations predicted a 2.2% rise in electric efficiency at nominal electrical output when 5% of the mass flow rate of air is replaced by steam.The steam injection experiments resulted in stable runs of the unit, a predicted reduction in shaft speed and increasing electrical efficiency. Validation of the ASPEN® simulations against the experimental data revealed the necessity for a more accurate determination of the air mass flow rate and more precise compressor characteristics.info:eu-repo/semantics/publishe
Water injection in a microgasturbine - Assessment of the performance using a black box method
info:eu-repo/semantics/publishe
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