Design of a model pipeline for testing of piezoelectric micro power generator for the Trans-Alaska Pipeline System

Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2007.Includes bibliographical references (leaf 27).In order to provide a reliable corrosion detection system for the Trans-Alaska Pipeline System (TAPS), a distributed wireless self-powered sensor array is needed to monitor the entire length of the pipeline at all times. Such a sensor faces two primary challenges: a method to provide power for the sensor, and a method to detect corrosion. This project has two goals: to build a model of the TAPS as a test bed for a piezoelectric micro power generator (PMPG), and to use the model to explore corrosion detection methods (perhaps by analyzing changes in the vibration spectrum), for use in the sensor array. To miniaturize the TAPS while maintaining its vibration spectrum, we will specify the dimensions of the model to have the same natural frequency, turbulent flow, and vortex induced vibrations as the actual pipeline. The model will serve as a test bed for various PMPG designs, and also serve as a starting point for exploring methods to detect corrosion in pipes. The primary vibration mode was found to be due to the natural frequency of the pipe, which was 20.2 Hz for the TAPS. Experimentally, we found the frequency to be in a range from 12-19 Hz. PMPG devices for use in the TAPS should be tuned to this frequency range.by Mike M. Lah.S.B

Oil palm leaf fibre and its suitability for paper-based products

Due to the shortage of wood as origin materials for paper-based production, agro-residue materials have been explored in the quest of finding the best alternative fibre. Oil palm leaf (OPL) is one of agro-residue that has potential due to its comparable characteristics with wood fibre. Studies on chemical compositions, fibre morphology, and mechanical property of OPL have been carried out aiming to evaluate its potential as a substitute raw material for pulp and paper-based production. The chemical compositions were analysed according to the TAPPI standard, Kurscher-Hoffner and chlorite methods accordingly. The mechanical property (tensile, tearing and bursting strengths) were determined as described in TAPPI test methods. Fibre dimensions were determined using Franklin method and analysed under the optical microscope. The content of cellulose in the OPL is determined to be 43.8%. Although, this result is lower than wood fibre (53%), OPL has higher hemicellulose content (36.4%) than the wood fibre (27.5%). In addition, the lignin content (19.7%) of OPL is in the low range of those in wood resources (18 - 25%). These parameters are important components to produce good quality pulp and will provide high mechanical strength of the paper-based products. The measured fibre length of oil palm leaf (1.13 mm) is shorter than the wood fibre (1.90 mm). Meanwhile, the mechanical property of OPL showed lower indexes than wood resources, however, tear (1.80 mN.m2/g) and burst (0.95 kPa.m2/g) indexes of OPL are higher than other published and successful wood resources (Eucalyptus). Based on the analyses, the oil palm leaf is indeed a suitable alternative of raw material for pulp and paper-based industries

Novel bi- and trifunctional inhibitors of tumor-associated proteolytic systems

Serine proteases, cysteine proteases, and matrix metalloproteinases (MMPs) are involved in cancer cell invasion and metastasis. Recently, a recombinant bifunctional inhibitor (chCysuPA(19-31)) directed against cysteine proteases and the urokinasetype plasminogen activator (uPA)/plasmin serine protease system was generated by introducing the uPA receptor (uPAR)binding site of uPA into chicken cystatin (chCysWT). In the present study, we designed and recombinantly produced multifunctional inhibitors also targeting MMPs. The inhibitors comprise the Nterminal inhibitory domain of human TIMP-1 (tissue inhibitor of matrix metalloproteinase-1) or TIMP-3, fused to chCysuPA(19-31) or chCysWT. As demonstrated by various techniques, these fusion proteins effectively interfere with all three targeted protease systems. In in vitro Matrigel invasion assays, the addition of recombinant inhibitors strongly reduced invasion of ovarian cancer cells (OVMZ-6\#8). Additionally, OVMZ 6\#8 cells were stably transfected with expression plasmids encoding the various inhibitors. Synthesis and secretion of the inhibitors was verified by a newly developed ELISA, which selectively detects the recombinant proteins. Invasive capacity of inhibitorproducing cells was significantly reduced compared to vectortransfected control cells. Thus, these novel, compact, and smallsize inhibitors directed against up to three different tumorassociated proteolytic systems may represent promising agents for prevention of tumor cell migration and metastasis

Bis[μ-2-(pyridin-2-yl)ethano­lato]bis­[bromidocopper(II)]

The title compound, [Cu2Br2(C7H8NO)2], was synthesized by reaction of CuBr2 with 2-(pyridin-2-yl)ethanol (hep-H) in methanol. The asymmetric unit consists of one hep ligand and a CuBr unit. The Cu2+ ion is thereby coordinated by the N atom and the deprotonated hydroxy O atom in a distorted square-planar geometry that is completed by another O atom. The latter acts as bridging ligand towards the second, symmetry-equivalent, Cu atom, thus generating a centrosymmetric dimeric unit, with the inversion centre halfway between the Cu atoms. These units are linked via C—H⋯Br and C—H⋯O hydrogen bonds, leading to the formation of a hydrogen-bonded one-dimensional-polymeric chain along a.

Bis(tetra­ethyl­ammonium) bis­(dimethyl­formamide)­tetra­kis­(μ-N,2-dioxido­benzene-1-carboximidato)penta­copper(II)

The title compound, (C8H20N)2[Cu5(C7H4NO3)4(C3H7NO)2], abbreviated as (TEA)2[CuII(12-MCCuII N(shi)-4](DMF)2 [where TEA is tetra­ethyl­ammonium, shi3− is salicyl­hydroximate (or N,2-dioxidobenzene-1-carboximidate) and DMF is N,N-dimethyl­formamide], contains five CuII ions. Four of the CuII ions are members of a metallacrown ring (MC), while the fifth CuII is bound in a central cavity. Two of the ring CuII ions are five-coordinate with distorted square-pyramidal geometry. The coordination sphere is composed of two shi3− ligands and one DMF mol­ecule. The other two ring CuII ions and the central CuII ion are four-coordinate with square-planar geometry. The coordination spheres of these ions are only composed of shi3− ligands. The charge of the [CuII(12-MCCuII N(shi)-4]2− unit is balanced by two uncoordinated TEA+ countercations. The structure shows severe static disorder with the metallacrown, the tetra­ethyl­ammonium cations and the DMF solvent mol­ecule all disordered over each of two mutually exclusive sites, with occupancy rates for the major moieties of 0.6215 (6) for the metallacrown, 0.759 (3) for the tetra­ethyl­ammonium ion and 0.537 (6) for the DMF mol­ecules. The metallacrown unit is located on a crystallographic inversion center and disordered about a non-crystallographic twofold axis. The DMF mol­ecule and the tetra­ethyl­ammonium ion are disordered about a non-crystallographic twofold axis and pseudo-inversion center, respectively

ALFALFA HI Data Stacking I. Does the Bulge Quench Ongoing Star Formation in Early-Type Galaxies?

We have carried out an HI stacking analysis of a volume-limited sample of ~5000 galaxies with imaging and spectroscopic data from GALEX and the Sloan Digital Sky Survey, which lie within the current footprint of the Arecibo Legacy Fast ALFA (ALFALFA) Survey. Our galaxies are selected to have stellar masses greater than 10^10 Msun and redshifts in the range 0.025<z<0.05. We extract a sub-sample of 1833 "early-type" galaxies with inclinations less than 70deg, with concentration indices C>2.6 and with light profiles that are well fit by a De Vaucouleurs model. We then stack HI line spectra extracted from the ALFALFA data cubes at the 3-D positions of the galaxies from these two samples in bins of stellar mass, stellar mass surface density, central velocity dispersion, and NUV-r colour. We use the stacked spectra to estimate the average HI gas fractions M_HI/M_* of the galaxies in each bin. Our main result is that the HI content of a galaxy is not influenced by its bulge. The average HI gas fractions of galaxies in both our samples correlate most strongly with NUV-r colour and with stellar surface density. The relation between average HI fraction and these two parameters is independent of concentration index C. We have tested whether the average HI gas content of bulge-dominated galaxies on the red sequence, differs from that of late-type galaxies on the red sequence. We find no evidence that galaxies with a significant bulge component are less efficient at turning their available gas reservoirs into stars. This result is in contradiction with the "morphological quenching" scenario proposed by Martig et al. (2009).Comment: 21 pages, 15 figures. Accepted for publication in MNRAS. Version with high resolution figures available at http://www.mpa-garching.mpg.de/GASS/pubs.ph

A Radio and Optical Polarization Study of the Magnetic Field in the Small Magellanic Cloud

We present a study of the magnetic field of the Small Magellanic Cloud (SMC), carried out using radio Faraday rotation and optical starlight polarization data. Consistent negative rotation measures (RMs) across the SMC indicate that the line-of-sight magnetic field is directed uniformly away from us with a strength 0.19 +/- 0.06 microGauss. Applying the Chandrasekhar-Fermi method to starlight polarization data yields an ordered magnetic field in the plane of the sky of strength 1.6 +/- 0.4 microGauss oriented at a position angle 4 +/- 12 degs, measured counter-clockwise from the great circle on the sky joining the SMC to the Large Magellanic Cloud (LMC). We construct a three-dimensional magnetic field model of the SMC, under the assumption that the RMs and starlight polarization probe the same underlying large-scale field. The vector defining the overall orientation of the SMC magnetic field shows a potential alignment with the vector joining the center of the SMC to the center of the LMC, suggesting the possibility of a "pan-Magellanic'' magnetic field. A cosmic-ray driven dynamo is the most viable explanation of the observed field geometry, but has difficulties accounting for the observed uni-directional field lines. A study of Faraday rotation through the Magellanic Bridge is needed to further test the pan-Magellanic field hypothesis.Comment: 28 pages, 6 figures, accepted for publication in Ap

Comparison of the Stellar Populations of Bulges and Discs using the MaNGA Survey

We use the MaNGA integral-field spectroscopic survey of low-redshift galaxies to compare the stellar populations of the bulge and disc components, identified from their Sersic profiles, for various samples of galaxies. Bulge dominated regions tend to be more metal-rich and have slightly older stellar ages than their associated disc dominated regions. The metallicity difference is consistent with the deeper gravitational potential in bulges relative to discs, which allows bulges to retain more of the metals produced by stars. The age difference is due to star formation persisting longer in discs relative to bulges. Relative to galaxies with lower stellar masses, galaxies with higher stellar masses tend to have bulge dominated regions that are more metal-rich and older (in light-weighted measurements) than their disc dominated regions. This suggests high-mass galaxies quench from the inside out, while lower-mass galaxies quench across the whole galaxy simultaneously. Early-type galaxies tend to have bulge dominated regions the same age as their disc dominated regions, while late-type galaxies tend to have disc dominated regions significantly younger than their bulge dominated regions. Central galaxies tend to have a greater metallicity difference between their bulge dominated regions and disc dominated regions than satellite galaxies at similar stellar mass. This difference may be explained by central galaxies being subject to mergers or extended gas accretion bringing new, lower-metallicity gas to the disc, thereby reducing the average metallicity and age of the stars; quenching of satellite discs may also play a role.Comment: Accepted by PAS