Pyrolysis and gasification of biomass and acid hydrolysis residues

This research was carried for an EC supported project that aimed to produce ethyl levulinate as a diesel miscible biofuel from biomass by acid hydrolysis. The objective of this research was to explore thermal conversion technologies to recover further diesel miscible biofuels and/or other valuable products from the remaining solid acid hydrolysis residues (AHR). AHR consists of mainly lignin and humins and contains up to 80% of the original energy in the biomass. Fast pyrolysis and pyrolytic gasification of this low volatile content AHR was unsuccessful. However, successful air gasification of AHR gave a low heating value gas for use in engines for power or heat with the aim of producing all the utility requirements in any commercial implementation of the ethyl levulinate production process. In addition, successful fast pyrolysis of the original biomass gave organic liquid yields of up to 63.9 wt.% (dry feed basis) comparable to results achieved using a standard hardwood. The fast pyrolysis liquid can be used as a fuel or upgraded to biofuels. A novel molybdenum carbide catalyst was tested in fast pyrolysis to explore the potential for upgrading. Although there was no deoxygenation, some bio-oil properties were improved including viscosity, pH and homogeneity through decreasing sugars and increasing furanics and phenolics. AHR gasification was explored in a batch gasifier with a comparison with the original biomass. Refractory and low volatile content AHR gave relatively low gas yields (74.21 wt.%), low tar yields (5.27 wt.%) and high solid yields (20.52 wt.%). Air gasification gave gas heating values of around 5MJ/NM3, which is a typical value, but limitations of the equipment available restricted the extent of process and product analysis. In order to improve robustness of AHR powder for screw feeding into gasifiers, a new densification technique was developed based on mixing powder with bio-oil and curing the mixture at 150°C to polymerise the bio-oil

Synthesis and Characterization of a Polypyridyl Ru(II)-Alloxazine Complex for Adsorption on TiO2-coated ITO Electrodes

TiO2-coated conducting glass electrodes can be modified by attachment of redox-active molecules to the TiO2 surface. This thesis describes the synthesis and characterization of a polypyridyl Ru(II) complex that can be covalently bound to a TiO2 surface through the carboxylate groups of 2,2\u27-bipyridine-4,4\u27 -dicarboxylic acid, H2dcbpy. In addition, the bound complex contains a redox-active alloxazine derivative, pptd, which is capable of 2e-/2H+ transfers. Thus the TiO2-coated electrode is modified with a transition metal complex capable of shuttling H-atoms to substrates in solution. Synthesis of the PF6- salt of this complex, [RuII(H2dcbpy)2pptd](PF6)2, proved challenging due to the difficulties in obtaining starting materials of sufficient purity. Details of the efforts to purify these materials are included. UV-Vis, 1H-NMR, and electrochemical characterization of [RuII(H2dcbpy)2pptd](PF6)2, and its adsorption to TiO2 electrodes, are included in the thesis. In addition, several well-known reference compounds have been characterized for comparison purposes

On The Numerical Solutions of Boundary Layer Equations of Williamson Fluid Past a Moving Plate

Laminar boundary layer flow of Williamson fluid over a moving plate is discussed in this paper. The governing equations of the flow problem are transformed into similarity equations using similarity technique. The reduced equations are numerically solved by finite difference method. The graphical presentation is discussed

Synthesis and Characterization of a Polypyridyl Ru(II)-Alloxazine Complex for Adsorption on TiO2-coated ITO Electrodes

TiO2-coated conducting glass electrodes can be modified by attachment of redox-active molecules to the TiO2 surface. This thesis describes the synthesis and characterization of a polypyridyl Ru(II) complex that can be covalently bound to a TiO2 surface through the carboxylate groups of 2,2\u27-bipyridine-4,4\u27 -dicarboxylic acid, H2dcbpy. In addition, the bound complex contains a redox-active alloxazine derivative, pptd, which is capable of 2e-/2H+ transfers. Thus the TiO2-coated electrode is modified with a transition metal complex capable of shuttling H-atoms to substrates in solution. Synthesis of the PF6- salt of this complex, [RuII(H2dcbpy)2pptd](PF6)2, proved challenging due to the difficulties in obtaining starting materials of sufficient purity. Details of the efforts to purify these materials are included. UV-Vis, 1H-NMR, and electrochemical characterization of [RuII(H2dcbpy)2pptd](PF6)2, and its adsorption to TiO2 electrodes, are included in the thesis. In addition, several well-known reference compounds have been characterized for comparison purposes

Floquet generation of Majorana end modes and topological invariants

We show how Majorana end modes can be generated in a one-dimensional system by varying some of the parameters in the Hamiltonian periodically in time. The specific model we consider is a chain containing spinless electrons with a nearest-neighbor hopping amplitude, a p-wave superconducting term and a chemical potential; this is equivalent to a spin-1/2 chain with anisotropic XY couplings between nearest neighbors and a magnetic field applied in the z-direction. We show that varying the chemical potential (or magnetic field) periodically in time can produce Majorana modes at the ends of a long chain. We discuss two kinds of periodic driving, periodic delta-function kicks and a simple harmonic variation with time. We discuss some distinctive features of the end modes such as the inverse participation ratio of their wave functions and their Floquet eigenvalues which are always equal to +/- 1 for time-reversal symmetric systems. For the case of periodic delta-function kicks, we use the effective Hamiltonian of a system with periodic boundary conditions to define two topological invariants. The first invariant is a well-known winding number while the second invariant has not appeared in the literature before. The second invariant is more powerful in that it always correctly predicts the numbers of end modes with Floquet eigenvalues equal to +1 and -1, while the first invariant does not. We find that the number of end modes can become very large as the driving frequency decreases. We show that periodic delta-function kicks in the hopping and superconducting terms can also produce end modes. Finally, we study the effect of electron-phonon interactions (which are relevant at finite temperatures) and a random noise in the chemical potential on the Majorana modes.Comment: 15 pages, 11 figures; added more numerical and analytical results about second topological invariant, and a discussion of effects of electron-phonon interactions and noise on Majorana end mode

Brain mitochondria from DJ-1 knockout mice show increased respiration-dependent hydrogen peroxide consumption

AbstractMutations in the DJ-1 gene have been shown to cause a rare autosomal-recessive genetic form of Parkinson’s disease (PD). The function of DJ-1 and its role in PD development has been linked to multiple pathways, however its exact role in the development of PD has remained elusive. It is thought that DJ-1 may play a role in regulating reactive oxygen species (ROS) formation and overall oxidative stress in cells through directly scavenging ROS itself, or through the regulation of ROS scavenging systems such as glutathione (GSH) or thioredoxin (Trx) or ROS producing complexes such as complex I of the electron transport chain. Previous work in this laboratory has demonstrated that isolated brain mitochondria consume H2O2 predominantly by the Trx/Thioredoxin Reductase (TrxR)/Peroxiredoxin (Prx) system in a respiration dependent manner (Drechsel et al., Journal of Biological Chemistry, 2010). Therefore we wanted to determine if mitochondrial H2O2 consumption was altered in brains from DJ-1 deficient mice (DJ-1−/−). Surprisingly, DJ-1−/− mice showed an increase in mitochondrial respiration-dependent H2O2 consumption compared to controls. To determine the basis of the increased H2O2 consumption in DJ1−/− mice, the activities of Trx, Thioredoxin Reductase (TrxR), GSH, glutathione disulfide (GSSG) and glutathione reductase (GR) were measured. Compared to control mice, brains from DJ-1−/− mice showed an increase in (1) mitochondrial Trx activity, (2) GSH and GSSG levels and (3) mitochondrial glutaredoxin (GRX) activity. Brains from DJ-1−/− mice showed a decrease in mitochondrial GR activity compared to controls. The increase in the enzymatic activities of mitochondrial Trx and total GSH levels may account for the increased H2O2 consumption observed in the brain mitochondria in DJ-1−/− mice perhaps as an adaptive response to chronic DJ-1 deficiency

Numerical Solution of 3rd order ODE Using FDM: On a Moving Surface in MHD Flow of Sisko Fluid

A Similarity group theoretical technique is used to transform the governing nonlinear partial differential equations of two dimensional MHD boundary layer flow of Sisko fluid into nonlinear ordinary differential equations. Then the resulting third order nonlinear ordinary differential equation with corresponding boundary conditions is linearised by Quasi linearization method. Numerical solution of the linearised third order ODE is obtained using Finite Difference method (FDM). Graphical presentation of the solution is given

Laminar Boundary Layer Flow of Sisko Fluid

The problem of steady two dimensional laminar boundary layer flow of non-Newtonian fluid is analyzed in the present paper. Sisko fluid model, one of the various fluid models of non- Newtonian fluid, is considered for stress-strain relationship. Similarity and numerical solutions obtained for the defined flow problem

(R1978) Heated Laminar Vertical Jet of Psudoplastic Fluids-Against Gravity

A heated laminar jet of Pseudo-plastic fluid flowing vertically upwards from a long narrow slit into a region of the same fluid which is at a rest and at a uniform temperature is considered. The governing non-linear Partial differential equations (PDEs) for the defined flow problem are transformed into non-linear ordinary differential equations using the effective similarity technique-one parameter deductive group theory method. The obtained non-linear coupled Ordinary differential equations are solved and the results are presented by graphs. The effect of the Prandtl number and Grashof number on the velocity and temperature of the jet flow is discussed. Also, a detailed discussion of some interesting applications of the vertical jet flow of pseudoplastic fluids in different fields of engineering and geophysics are provided