127 research outputs found

    Computer simulation of a Linde double column

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    The purpose of this thesis is to develop a Fortran Computer Program to simulate the operation of a Linde Double Column for the separation of air into oxygen and nitrogen. The model outputs the number of contact stages required, the reflux ratio, the heat loads (condenser and reboiler, and the five profiles of temperature, pressure, vapor flow rate, liquid flow rate, and light component composition. From this data, the proposed design can be evaluated, and the effect of varying operating conditions explored

    Effects of solvent additive on "s-shaped" curves in solution-processed small molecule solar cells.

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    A novel molecular chromophore, p-SIDT(FBTThCA8)2, is introduced as an electron-donor material for bulk heterojunction (BHJ) solar cells with broad absorption and near ideal energy levels for the use in combination with common acceptor materials. It is found that films cast from chlorobenzene yield devices with strongly s-shaped current-voltage curves, drastically limiting performance. We find that addition of the common solvent additive diiodooctane, in addition to facilitating crystallization, leads to improved vertical phase separation. This yields much better performing devices, with improved curve shape, demonstrating the importance of morphology control in BHJ devices and improving the understanding of the role of solvent additives

    Impact of interfacial molecular orientation on radiative recombination and charge generation efficiency.

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    A long standing question in organic electronics concerns the effects of molecular orientation at donor/acceptor heterojunctions. Given a well-controlled donor/acceptor bilayer system, we uncover the genuine effects of molecular orientation on charge generation and recombination. These effects are studied through the point of view of photovoltaics-however, the results have important implications on the operation of all optoelectronic devices with donor/acceptor interfaces, such as light emitting diodes and photodetectors. Our findings can be summarized by two points. First, devices with donor molecules face-on to the acceptor interface have a higher charge transfer state energy and less non-radiative recombination, resulting in larger open-circuit voltages and higher radiative efficiencies. Second, devices with donor molecules edge-on to the acceptor interface are more efficient at charge generation, attributed to smaller electronic coupling between the charge transfer states and the ground state, and lower activation energy for charge generation.Molecular orientation profoundly affects the performance of donor-acceptor heterojunctions, whilst it has remained challenging to investigate the detail. Using a controllable interface, Ran et al. show that the edge-on geometries improve charge generation at the cost of non-radiative recombination loss

    [η5-2,3-Bis(trimethylsilyl)-2,3-dicarba-nido-hexaborane(2−)]chlorido(N,N,N′,N′-tetramethylethylenediamine)dysprosium(III)

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    The structure of the title compound, [Dy(C8H22B4Si2)Cl(C6H16N2)], reveals that a center of symmetry exists within the dimeric half-sandwich units. Within each half-sandwich, the DyIII ion is coordinated by the five-membered ring of the carborane, tetramethylethyl­enediamine and the chloride ion

    Human Genotyping and An Experimental Model Reveal NPR-C as A Possible Contributor to Morbidity In Coarctation Of The Aorta

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    Coarctation of the aorta (CoA) is a common congenital cardiovascular (CV) defect characterized by a stenosis of the descending thoracic aorta. Treatment exists, but many patients develop hypertension (HTN). Identifying the cause of HTN is challenging because of patient variability (e.g., age, follow-up duration, severity) and concurrent CV abnormalities. Our objective was to conduct RNA sequencing of aortic tissue from humans with CoA to identify a candidate gene for mechanistic studies of arterial dysfunction in a rabbit model of CoA devoid of the variability seen with humans. We present the first known evidence of natriuretic peptide receptor C (NPR-C; aka NPR3) downregulation in human aortic sections subjected to high blood pressure (BP) from CoA versus normal BP regions (validated to PCR). These changes in NPR-C, a gene associated with BP and proliferation, were replicated in the rabbit model of CoA. Artery segments from this model were used with human aortic endothelial cells to reveal the functional relevance of altered NPR-C activity. Results showed decreased intracellular calcium ([Ca2+]i) activity to C-type natriuretic peptide (CNP). Normal relaxation induced by CNP and atrial natriuretic peptide was impaired for aortic segments exposed to elevated BP from CoA. Inhibition of NPR-C (M372049) also impaired aortic relaxation and [Ca2+]i activity. Genotyping of NPR-Cvariants predicted to be damaging revealed that rs146301345 was enriched in our CoA patients, but sample size limited association with HTN. These results may ultimately be used to tailor treatment for CoA based on mechanical stimuli, genotyping, and/or changes in arterial function

    The effect of intermolecular interaction on excited states in p − DTS(FBTTH 2

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    Using optical spectroscopy in solution and thin film, and supported by quantum chemical calculations, we investigated the aggregation process of the donor-acceptor type molecule p − DTS(FBTTH2)2. We demonstrate that cooling a solution induces a disorder-order phase transition that proceeds in three stages analogous to the steps observed in semi-rigid conjugated polymers. By analyzing the spectra, we are able to identify the spectral signature of monomer and aggregate in absorption and emission. From this we find that in films, the fraction of aggregates is near 100% which is in contrast to films made from semi-rigid conjugated polymers

    Target highlights in CASP9: Experimental target structures for the critical assessment of techniques for protein structure prediction

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    15 pags, 9 figsOne goal of the CASP community wide experiment on the critical assessment of techniques for protein structure prediction is to identify the current state of the art in protein structure prediction and modeling. A fundamental principle of CASP is blind prediction on a set of relevant protein targets, that is, the participating computational methods are tested on a common set of experimental target proteins, for which the experimental structures are not known at the time of modeling. Therefore, the CASP experiment would not have been possible without broad support of the experimental protein structural biology community. In this article, several experimental groups discuss the structures of the proteins which they provided as prediction targets for CASP9, highlighting structural and functional peculiarities of these structures: the long tail fiber protein gp37 from bacteriophage T4, the cyclic GMP-dependent protein kinase Iβ dimerization/docking domain, the ectodomain of the JTB (jumping translocation breakpoint) transmembrane receptor, Autotaxin in complex with an inhibitor, the DNA-binding J-binding protein 1 domain essential for biosynthesis and maintenance of DNA base-J (β-D-glucosyl-hydroxymethyluracil) in Trypanosoma and Leishmania, an so far uncharacterized 73 residue domain from Ruminococcus gnavus with a fold typical for PDZ-like domains, a domain from the phycobilisome core-membrane linker phycobiliprotein ApcE from Synechocystis, the heat shock protein 90 activators PFC0360w and PFC0270w from Plasmodium falciparum, and 2-oxo-3-deoxygalactonate kinase from Klebsiella pneumoniae. © 2011 Wiley-Liss, Inc.Grant sponsor: Spanish Ministry of Education and Science; Grant number: BFU2008-01588; Grant sponsor: European Commission; Grant number: NMP4-CT-2006-033256; Grant sponsor: Spanish Ministry of Education and Science (José Castillejo fellowship); Grant sponsor: Xunta de Galicia (Angeles Alvariño fellowship); Grant sponsor: National Institutes of Health; Grant numbers: K22-CA124517 (D.E.C.); R01-GM090161 (C.K.) GM074942; GM094585; Grant sponsor: U. S. Department of Energy, Office of Biological and Environmental Research; Grant number: DE-AC02-06CH11357 (to A.J.); Grant sponsor: Foundation for Polish Science (to K.M.); Grant sponsor: NSF; Grant number: DBI 0829586

    Pulsar Recoil and Gravitational Radiation due to Asymmetrical Stellar Collapse and Explosion

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    New data imply that the average velocity of radio pulsars is large \cite{hla93}. Under the assumption that these data imply that a pulsar is born with an ``intrinsic'' kick, we investigate whether such kicks can be a consequence of asymmetrical stellar collapse and explosion. We calculate the gravitational wave (GW) signature of such asymmetries due to anisotropic neutrino radiation and mass motions. We predict that any recoils imparted to the neutron star at birth will result in a gravitational wave strain, hzzTT^{TT}_{zz}, that does not go to zero with time. Hence, there may be ``memory'' \cite{bt87} in the gravitational waveform from a protoneutron star that is correlated with its recoil and neutrino emissions.Comment: 13 Pages, APS REVTeX format, encapsulated postscript figures, uuencoded and compressed. Accepted for publication in Phys. Rev. Letter
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