A robotic platform for high-throughput electrochemical analysis of chalcopyrite leaching

A novel robotic platform for combinatorial screening of ionic liquid-based Cu extraction from chalcopyrite with real-time, in situ monitoring of dissolved copper.</p

Development and testing of a combined catalyst/sorbent core-in-shell material for the production of high concentration hydrogen

A combined catalyst and sorbent for the production of hydrogen from CH4 or CO was developed and tested. The combined catalyst and sorbent was a spherical multi-layered material having a CaO-based sorbent core and an outer shell composed mainly of alumina. The CaO sorbent core was employed to absorb CO2, one of the reaction products. The alumina shell protected the friable CaO core and also supported a Ni catalyst. The development of the material focused separately on the development of the core and shell. First, since the CO2 absorption capacity of CaO-based sorbents diminishes as they are repeatedly used and regenerated, the development of a more stable CaO-based sorbent was investigated. Both the addition of MgO, which acted as a sintering inhibitor, and severe initial calcination conditions for the CaO precursor limestone produced a more stable CaO sorbent. Second, an alumina-based material with good physical strength and high surface area was developed to serve as the shell of the core-in-shell material. The addition of either fine particle limestone or lanthanum oxide to the alumina shell formulation produced a material with enhanced physical strength, which was most likely due to the formation of a binding aluminate phase. Reaction testing of the core-in-shell pellets with a 3:1 molar ratio of H2O:CH4 in the feed produced a high concentration of H2 via simultaneous application of the steam-methane reforming reaction, the water-gas shift reaction and the reaction of CO2 with CaO. This testing was conducted with a tubular fixed bed reactor over a temperature range of 550-650yC and a pressure range of 1.0-10.0 atm. The rapid absorption of CO2 by CaO produced CH4 and CO conversions greater than would have been possible without a sorbent. Lifecycle testing determined that a high concentration of H2 could be produced over 10 cycles of H2 production and sorbent regeneration. However, the length of time that H2 was produced diminished with each cycle due to a loss of CO2 absorption capacity by the CaO sorbent. Physical characterization of the pellets after lifecycle testing also revealed that some pellets fractured during lifecycle testing and that the Ni catalyst sintered. Core-in-shell pellets with alternate shell formulations were also tested in the fixed bed reactor for the production of high concentrations of H2 from a mixture of CO and steam via the water-gas shift reaction. Three alumina shell formulations were tested: a formulation with mostly alumina in the shell, a formulation with 10 wt% Fe2O3 added to the alumina shell formulation and a formulation with Ni impregnated onto the shell. The rapid absorption of CO2 by the sorbent allowed for a high concentration of H2 to be produced and a high CO conversion to be achieved between 550-600yC at 1.0 atm with any of these formulations. However, once the CaO sorbent became loaded, only the formulation with Ni present converted CO to reaction equilibrium levels. On the other hand, by absorbing CO2 the formulation with mainly alumina in the shell appeared to be an attractive material for the production of H2 from syngas. Furthermore, this formulation would be resistant to sulfurous gases that might be present

Zur Interpretation der Dosiswirkungsbeziehungen in der Strahlenbiologie

Der Zufallscharakter zellulärer Strahleneffekte muß nicht stets auf einer Variabilität der Strahlenempfindlichkeit oder auf einer inhomogenen Verteilung der absorbierten Energie auf die Einheiten einer bestrahlten Population oder ihre ldquorTreffbereicheldquo beruhen, sondern kann auch bei einer kontinuierlich mit der Dosis zunehmenden ldquordispersen Vorschädigungldquoaller Einheiten zustandekommen, wenn diese die inhärente Labilität des lebenden Systems erhöht. Das zufallsartige ldquorkritische Ereignisldquo, das über das Eintreten der Testreaktion entscheidet, muß daher nicht unbedingt schon durch die Energieabsorption gegeben sein, sondern kann in einem späteren Glied der Ursachenkette liegen. Charakteristisch für den Verlauf von Überlebenskurven ist ihre Neigung in halblogarithmischer Darstellung; wir bezeichnen diese Größe als ldquorReaktivitätldquo. Kurvenformen, die bisher durch den Mehrtreffer- oder Mehrbereichsansatz gedeutet wurden, ergeben sich auch, wenn man allein die Tatsache berücksichtigt, daß die Reaktivität mit der Dosis ansteigen kann. Strebt die Reaktivität mit steigender Dosis einem Endwert zu, so kann dies darauf beruhen, daß eine dem vitalen Objekt inhärente Kompensationsfähigkeit sich mit der Dosis erschöpft. In einigen Fällen wird die biochemische Natur einer solchen Kompensationsfähigkeit bereits deutlich

Which way up? Recognition of homologous DNA segments in parallel and antiparallel alignment

Homologous gene shuffling between DNA promotes genetic diversity and is an important pathway for DNA repair. For this to occur, homologous genes need to find and recognize each other. However, despite its central role in homologous recombination, the mechanism of homology recognition is still an unsolved puzzle. While specific proteins are known to play a role at later stages of recombination, an initial coarse grained recognition step has been proposed. This relies on the sequence dependence of the DNA structural parameters, such as twist and rise, mediated by intermolecular interactions, in particular electrostatic ones. In this proposed mechanism, sequences having the same base pair text, or are homologous, have lower interaction energy than those sequences with uncorrelated base pair texts; the difference termed the recognition energy. Here, we probe how the recognition energy changes when one DNA fragment slides past another, and consider, for the first time, homologous sequences in antiparallel alignment. This dependence on sliding was termed the recognition well. We find that there is recognition well for anti-parallel, homologous DNA tracts, but only a very shallow one, so that their interaction will differ little from the interaction between two nonhomologous tracts. This fact may be utilized in single molecule experiments specially targeted to test the theory. As well as this, we test previous theoretical approximations in calculating the recognition well for parallel molecules against MC simulations, and consider more rigorously the optimization of the orientations of the fragments about their long axes. The more rigorous treatment affects the recognition energy a little, when the molecules are considered rigid. However when torsional flexibility of the DNA molecules is introduced, we find excellent agreement between analytical approximation and simulation.Comment: Paper with supplemental material attached. 41 pages in all, 4 figures in main text, 3 figures in supplmental. To be submitted to Journa

On the presence of mid-gap states in CaV4O9

Using exact diagonalizations of finite clusters with up to 32 sites, we study the $J_1-J_2$ model on the 1/5 depleted square lattice. Spin-spin correlation functions are consistent with plaquette order in the spin gap phase which exists for intermediate values of $J_2/J_1$. Besides, we show that singlet states will be present in the singlet-triplet gap if $J_2/J_1$ is not too small ($J_2/J_1 \gtrsim 0.47$). We argue that this property should play a central role in determining the exchange integrals in ${\rm CaV}_4{\rm O}_9$Comment: 4 pages, 5 postscript figure

Following a "Collapsing" Wavefunction

I study the quantum mechanics of a spin interacting with an ``apparatus''. Although the evolution of the whole system is unitary, the spin evolution is not. The system is chosen so that the spin exhibits loss of quantum coherence, or ``wavefunction collapse'', of the sort usually associated with a quantum measurement. The system is analyzed from the point of view of the spin density matrix (or ``Schmidt paths''), and also using the consistent histories approach. These two points of view are contrasted with each other. Connections between the results and the form of the Hamiltonian are discussed in detail.Comment: 30 pages, plain LaTex, 3 figures in a separate uuencoded fil

Nurses Alumni Association Bulletin, Fall 2010

2010 - 2011 Meeting Date Calendar 2011 Annual Luncheon & Meeting Notice Officers, Committee Chairs, Satellite and Volunteers Bulletin Publication Committee The President\u27s Message Treasurer\u27s Report Resume of Minutes Office News Committee Reports Social Relief Trust Fund Satellite - Harrisburg Satellite Area Scholarship Nominating Bulletin Development Annual Giving Janet C. Hindson Award Janet C. Hindson Award Criteria Janet C. Hindson Award Recipient and Nominees Janet C. Hindson Lifetime Achievement Award Assisting in the HIV I Aids Epidemic in Lesotho, Africa News About and From our Graduates Memories Era Ending Happy Birthday To Be 80 or More 50th Anniversary Class Lists for 1960 Luncheon Attendees 1961 - Anniversary Class List for 2011 Annual Luncheon Center page Why Not? It\u27s Our Money! In Memoriam, Names of Deceased Graduates Class News Additional Information, Pins, Transcript & Address Info Scholarship Fund Application Certification Reimbursement Application Relief Fund Application List of Hotels Campus Map Constitution & By-Laws Revision

Large Extra Dimensions from a Small Extra Dimension

Models with extra dimensions have changed our understanding of the hierarchy problem. In general, these models explain the weakness of gravity by diluting gravity in a large bulk volume, or by localizing the graviton away from the standard model. In this paper, we show that the warped geometries necessary for the latter scenario can naturally induce the large volumes necessary for the former. We present a model in which a large volume is stabilized without supersymmetry. We comment on the phenomenology of this scenario and generalizations to additional dimensions.Comment: Some formulae altered, conclusions unchange