Hedge Ratios and Hedging Effectiveness of the SPI Futures Contract

In this paper two hedging models are studied in the context of the SPI futures. I analyze the hedge ratio and hedging effectiveness of the models relative to the naive hedging model. Firstly, I find that Working's (1953) strategy enhances the performance of hedging over the naive strategy. Secondly, based on risk reduction, the Variance Minimization model is found to be very useful. It performs better than the naive model. The hedging effectiveness of a longer hedge duration is found to be more effective than a shorter one. Finally, the effects of time to expiration on hedge ratio and hedging effectiveness are not clear

Bio-electrocatalysis using immobilized enzymes and microorganisms

Regarding to the increase in population and industry development, global energy demand tends to increase continuously. However, our main source of energy, the fossil fuels, like coal, oil and natural gas, are limited and start running out. Moreover, the combustion of such fossil-based energy carriers gives carbon dioxide (CO2) back to the atmosphere which is considered as the major cause of the rising of global temperature. Therefore, renewable, cleaner and more sustainable energy sources are urgently needed. Converting inexhaustible energy (such as solar and wind energy) into chemicals or artificial fuels offers transportable fuels which are independent from place and time. One promising approach is to convert exhausted CO2 into fuels, for example, formate, methane and methanol using renewable energies like solar and wind. Developed from such idea, this study is aimed to investigate electrochemical systems for the conversion of CO2 to value-added chemicals products by using bio-origin catalysts such as microorganisms and enzymes. Herein, microbial electrolysis cells containing Methylobacterium extorquens, acetogenic bacteria, were developed and their catalytic activities towards the conversion of CO2 to formate were monitored under applying of a constant potential. In this part, direct electron injection and mediator-assisted approaches were investigated. Neutral red, a biocompatible dye, was introduced into the systems as redox mediator in two ways: homogeneous (dissolved in the solution) and heterogeneous (electropolymerized onto the electrode). Electrochemical characterization of such systems was carried out by means of cyclic voltammetry and electrolysis showing electrocatalytic activities towards the CO2 reduction to formate. The performance was found to be enhanced with the aid of mediator in both systems. Further investigation was performed by combining two bioelectrodes, bioanode and biocathode, which were developed from sewage sludge containing mixed culture microorganism, together in bio-electrochemical systems. The systems were developed serving as a wastewater treatment system where organic substances were oxidized at bioanode and CO2 was reduced to methane (CH4) at biocathode. Such system was successfully built up and system performance was investigated by monitoring chemical oxygen demand values and CH4 amount. Additionally, electrode modifications for both electrodes using poly(neutral red) and chitosan approaches were carried out. The results revealed improved overall performance in both organics degradation and CH4 production. In addition, dehydrogenase enzymes were investigated as electrocatalysts in electrochemical catalytic system. The dehydrogenases are redox enzymes that catalyze redox reactions and require sacrificial electron donor such as nicotinamide adenine dinucleotide, reduced form (NADH). Avoiding using such costly cofactor, electrochemical injection of electrons from electrode directly into enzymes active sites is suggested. Efficient immobilization of enzymes onto the electrode was presented by chemical grafting of conjugated dehydrogenases directly onto graphene (as a conductive nanoplatform). Using an alginate hydrogel matrix, we subsequently coated this bio-nano-electrocatalyst onto the electrode. This immobilization technique was employed for single dehydrogenase for the reduction of acetaldehyde to ethanol and furthermore, of three dehydrogenases for the cascade reduction of CO2 all the way to methanol. The enzyme-graphene bio-nano-electrocatalysts show enhanced reductive current delivered into the system, leading to higher production rate.Author Hathaichanok SeelajaroenUniversität Linz, Dissertation, 2020(VLID)494987

Enhanced BioElectrochemical Reduction of Carbon Dioxide by Using Neutral Red as a Redox Mediator

Microbial electrosynthetic cells containing Methylobacterium extorquens were studied for the reduction of CO2 to formate by direct electron injection and redox mediatorassisted approaches, with CO2 as the sole carbon source. The formation of a biofilm on a carbon felt (CF) electrode was achieved while applying a constant potential of 0.75V versus Ag/AgCl under CO2saturated conditions. During the biofilm growth period, continuous H2 evolution was observed. The longterm performance for CO2 reduction of the biofilm with and without neutral red as a redox mediator was studied by an applied potential of 0.75V versus Ag/AgCl. The neutral red was introduced into the systems in two different ways: homogeneous (dissolved in solution) and heterogeneous (electropolymerized onto the working electrode). The heterogeneous approach was investigated in the microbial system, for the first time, where the CF working electrode was coated with poly(neutral red) by the oxidative electropolymerization thereof. The formation of poly(neutral red) was characterized by spectroscopic techniques. During longterm electrolysis up to 17 weeks, the formation of formate was observed continuously with an average Faradaic efficiency of 4%. With the contribution of neutral red, higher formate accumulation was observed. Moreover, the microbial electrosynthetic cell was characterized by means of electrochemical impedance spectroscopy to obtain more information on the CO2 reduction mechanism.Z222-N19848862861392(VLID)356325

Impact of Carbon Felt Electrode Pretreatment on Anodic Biofilm Composition in Microbial Electrolysis Cells

Sustainable technologies for energy production and storage are currently in great demand. Bioelectrochemical systems (BESs) offer promising solutions for both. Several attempts have been made to improve carbon felt electrode characteristics with various pretreatments in order to enhance performance. This study was motivated by gaps in current knowledge of the impact of pretreatments on the enrichment and microbial composition of bioelectrochemical systems. Therefore, electrodes were treated with poly(neutral red), chitosan, or isopropanol in a first step and then fixed in microbial electrolysis cells (MECs). Four MECs consisting of organic substance-degrading bioanodes and methane-producing biocathodes were set up and operated in batch mode by controlling the bioanode at 400 mV vs. Ag/AgCl (3M NaCl). After 1 month of operation, Enterococcus species were dominant microorganisms attached to all bioanodes and independent of electrode pretreatment. However, electrode pretreatments led to a decrease in microbial diversity and the enrichment of specific electroactive genera, according to the type of modification used. The MEC containing isopropanol-treated electrodes achieved the highest performance due to presence of both Enterococcus and Geobacter. The obtained results might help to select suitable electrode pretreatments and support growth conditions for desired electroactive microorganisms, whereby performance of BESs and related applications, such as BES-based biosensors, could be enhanced

Indigoidine - Biosynthesized organic semiconductor

Indigoidine is a blue natural pigment, which can be efficiently synthetized in E. coli. In addition to its antioxidant and antimicrobial activities indigoidine due to its stability and deep blue color can find an application as an industrial, environmentally friendly dye. Moreover, similarly to its counterpart regular indigo dye, due to its molecular structure, indigoidine is an organic semiconductor. Fully conjugated aromatic moiety and intermolecular hydrogen bonding of indigoidine result in an unusually narrow bandgap for such a small molecule. This, in its turn, result is tight molecular packing in the solid state and opens a path for a wide range of application in organic and bio-electronics, such as electrochemical and field effect transistors, organic solar cells, light and bio-sensors etc