Biological coal desulfurization

Sulfur removal from coal before combustion is of considerable interest to avoid emission of oxides of sulfur(SOx). Chemical and physical methods have been developed for removing the inorganic sulfur component in coal. This component is generally associated with pyrites(FeS2). However, no commerical methods have been developed for the removal of the organic sulfur conponent. This study describes microbial methods for removing organically bound sulfur from coal. The specific goals of this study were to ascertain whether a robust biologically active population such as activated sludge biomass can remove organic sulfur from coal and to devise sulfur analytical methods that are less cumbersome than the accepted standards for screening research results. Dibenzothiophene is used in isolating microorganisms that use sulfur as the sole source for growth. It was found that about 55% sulfur can be removed by activated sludge in shaker flasks from a coal which was previously treated to remove inorganic sulfur(IBC-108). A no cycling leaching reactor with activated sludge removed 50% sulfur from the same type of coal. Almost 72% sulfur is removed by A-i, S-Dl, T3-2 and Ar-i mixed cultures. It was also found that about 25 to 29% sulfur can be removed by different cultures from a commercially prepared washed coal in which the pyritic and organic sulfur have not been altered. The application of ion-chromatography and atomic spectrometry in analyzing sulfate, pyritic sulfur, organic sulfur and total sulfur following ASTM extraction can achieve easier and quicker sulfur determinations without sacrificing accuracy and reproducibility

Quantum Spin Hall Insulators with Interactions and Lattice Anisotropy

We investigate the interplay between spin-orbit coupling and electron-electron interactions on the honeycomb lattice combining the cellular dynamical mean-field theory and its real space extension with analytical approaches. We provide a thorough analysis of the phase diagram and temperature effects at weak spin-orbit coupling. We systematically discuss the stability of the quantum spin Hall phase toward interactions and lattice anisotropy resulting in the plaquette-honeycomb model. We also show the evolution of the helical edge states characteristic of quantum spin Hall insulators as a function of Hubbard interaction and anisotropy. At very weak spin-orbit coupling and intermediate electron-electron interactions, we substantiate the existence of a quantum spin liquid phase.Comment: 7 pages, 9 figures, final versio

Modelling of ground penetrating radar backscatter for water pipeline leakage detection

Subsurface water leaks not only waste precious natural resources, but also create substantial damages to the transportation system and structures within urban and suburban environments. While many geophysical techniques have been suggested for detecting water leakage including ground-penetrating radar (GPR), acoustic devices, gas sampling devices and pressure wave detectors, there is no ideal solution for it. Nonetheless, GPR, a non-destructive geophysical technique which uses high frequency electromagnetic waves to acquire subsurface information has been regularly utilized as GPR responds to the changes in electrical properties, which is a function of soil and rock material, and moisture content. To evaluate the feasibility of GPR in detecting water pipe leakage, a finite-difference time-domain (FDTD) numerical modelling is conducted together with water pipe leakage detection fieldwork and experimental test. To properly design the features of the imaging approach, and test its capabilities in controlled conditions, the synthetic data was generated in a two dimensional FDTD forward modelling solver capable of accurately simulating real world GPR scenarios. Different types of simulate conditions involving sizes of leakage area, frequencies (250 MHz and 700 MHz), pipe materials (AC, DI, PVC, MS and HDPE) and pipe sizes (100mm, 200mm and 300mm) were conducted. For the fieldwork, case studies were carried out using GPR scanning equipment (Detector Duo) to validate FDTD numerical model. For the experimental test, Detector Duo was used to collect data on top of District Metering Areas testbed. More understanding regarding the signature of leakage was gained in radargram. Compared to a distinct hyperbola or line as shown in radargram of intact pipes, the leakage zone is disturbed by the wave reflection caused by saturated soil. Numerically simulated results seem to be in agreement with the case studies and experimental results. The signature of pipe and leakage are clearly visible in the simulated radargram compared with those in the case studies and experimental radargram. Therefore, GPR survey seems promising as an efficient non-destructive geophysical technique for leakage detection approach. This finding is useful to provide protocols for GPR profile interpretation, particularly in underground water pipe leakage detection

Simulation of an all-optical 1 x 2 SMZ switch with a high contrast ratio

Abstract — An all-optical 1×2 high contrast ratio (CR) switch based on the symmetric Mach-Zehnder (SMZ) interferometers is presented. Simulation results show a remarkable improvement of the inter-output CR (~25 dB) between the two outputs compared with an existing SMZ switch. It is shown that the proposed switch offers high values of inter-output CR (> 32dB) over a wide range of input powers using appropriate power of the control pulses. I

Entanglement criterion via general symmetric informationally complete measurements

We study the quantum separability problem by using general symmetric informationally complete measurements and present a separability criterion for arbitrary dimensional bipartite systems. We show by detailed examples that our criterion is more powerful than the existing ones in entanglement detection.Comment: 8 pages, 5 figure