622 research outputs found
A programme of symptom management for improving quality of life and drug adherence in AIDS/HIV patients
No full textMicrostrain in pyrope-grossular garnet solid solution at high pressure: a case study of Py(90)Gr(10) and Py(10)Gr(90) up to 15 GPa
No full textSingle-phase, well-sintered, translucent polycrystalline garnets with compositions of Py(90)Gr(10) and Py(10)Gr(90) were synthesized at 6 GPa and 1400 degrees C using a multi-anvil apparatus. X-ray diffraction (XRD) data for these garnet solid solutions were collected with both high-resolution synchrotron X-ray and standard laboratory X-ray sources. Analysis of the FWHM of the XRD peaks using Williamson-Hall plot yields microstrains around 0.12% for Py(90)Gr(10) and 0.09% for Py(10)Gr(90). The FWHM of Py(10)Gr(90) garnet as well as the derived microstrain remains constant up to 11 GPa, followed by a continuous increase to the experimental peak pressure 15 GPa caused by elastic strain in response to deviatoric/anisotropic stresses. The FWHM and microstrain for Py(90)Gr(10) remain constant to the measurement limit at 7 GPa. The microstrain of pyrope-grossular garnets exhibits a nonlinear dependence on composition, showing two peaks near Py(20)Gr(80) and Py(80)Gr(20), which may be associated with local structural heterogeneities arising from Mg and Ca substitution. Using a third-order Birch-Murnaghan equation of state, the bulk modulus is constrained to be Ie (0) = 171.8 +/- 2.1 GPa (with K-0(') fixed to 5.92) for Py(10)Gr(90) and Ie (0) = 174.3 +/- 2.5 GPa (with K-0(') fixed to 4.4) for Py(90)Gr(10), both of which are much larger than that for intermediate composition close to Py(50)Gr(50) but comparable to that for their corresponding end members. The relatively larger microstrain and higher bulk moduli for Py(10)Gr(90) and Py(90)Gr(10) garnets could be related to short-range ordering of Mg and Ca cations in garnet structure due to substitution, which results in different local environments for Mg and Ca cations along the pyrope-grossular solid solution.DOE/NNSA [DE-NA0002907]; NSF [EAR1524078]SCI(E)ARTICLE6377-3884
atomneb/AtomNeb-py: AtomNeb-py.0.3.0
No full textAtomNeb - Python Package for Atomic Data of Ionized Nebulae
AtomNeb is a database containing atomic data stored in FITS file format generated for for spectral analysis. The AtomNeb Python Package is equipped with several API functions developed in the Python language, which can be used to read atomic data from the AtomNeb FITS files. The API functions of the AtomNeb Python Package, together with the pyEQUIB Python Package, can be used to carry out plasma diagnostics and abundance analysis of spectra emitted from ionized nebulae.
Update Summary
Change data structures from pandas.DataFrame to NumPy
Add Chianti 9.0 atomic data
Citation
@article{Danehkar2020,
author = {{Danehkar}, Ashkbiz},
title = {AtomNeb Python Package, an addendum to AtomNeb: IDL Library for Atomic Data of Ionized Nebulae},
journal = {Journal of Open Source Software},
volume = {5},
number = {55},
pages = {2797},
year = {2020},
doi = {10.21105/joss.02797}
Photodegradation of pyrogenic dissolved organic matter (Py-DOM): a combined photon counting and distribution-based FT-ICR MS study
No full textQuantitative systematic studies are needed to elucidate the both short and long-term environmental implications of increasing pyrogenic dissolved organic matter (Py-DOM) inputs associated with projected increase in wildfire activity over the next century. Time-resolved fluorescence spectroscopy and Fourier transform ion cyclotron resonance were used to characterize extracts of unaltered and pyrolyzed wood and plant material. Upon pyrolysis, extracts shifted from a predominantly phenolic signature to a carboxylic-rich alicyclic configuration. Photodegradation of extracts was commensurate with solar energy exposure. The rate of photodegradation and the degradable fraction of DOM was component driven. Results of this study point to a disproportionate energy-induced response in components common to lignocellulose-derived DOM. Further studies are required to elucidate the mechanistic aspect of photodegradation of DOM, and Py-DOM as relates to energy input
atomneb/AtomNeb-py: AtomNeb-py.0.3.3
No full textAtomNeb - Python Package for Atomic Data of Ionized Nebulae
AtomNeb is a database containing atomic data stored in FITS file format generated for for spectral analysis. The AtomNeb Python Package is equipped with several API functions developed in the Python language, which can be used to read atomic data from the AtomNeb FITS files. The API functions of the AtomNeb Python Package, together with the pyEQUIB Python Package, can be used to carry out plasma diagnostics and abundance analysis of spectra emitted from ionized nebulae.
Update Summary
Add Jupyter Notebooks
Citation
@article{Danehkar2020,
author = {{Danehkar}, Ashkbiz},
title = {AtomNeb Python Package, an addendum to AtomNeb: IDL Library for Atomic Data of Ionized Nebulae},
journal = {Journal of Open Source Software},
volume = {5},
number = {55},
pages = {2797},
year = {2020},
doi = {10.21105/joss.02797}
In-plane spin reorientation transition in Co/Py bilayers grown epitaxially on vicinal Cu(001)
No full textCo/Py bilayers were grown epitaxially onto a vicinal Cu(001) substrate with the atomic steps parallel to the [110] crystalline axis. We show that the magnetization in vicinal Cu/Co/Py/Cu(001) undergoes an in plane spin reorientation transition (SRT) from perpendicular to parallel direction of the steps as the Co film thickness increases. By performing Rotation Magneto-Optic Kerr Effect (ROTMOKE) measurement as a function of both the Py and the Co film thicknesses, we show that the observed in-plane SRT results from a competition between the step-induced uniaxial anisotropies in the Py and Co films that favor the Py and Co magnetizations perpendicular and parallel to the atomic steps, respectively. Step decoration experiment further shows that the uniaxial anisotropy originates from the step edges of the vicinal surface. (C) 2016 Elsevier B.V. All rights reserved.National Science Foundation NRF through the Global Research Laboratory project of Korea [DMR-1504568]; China Scholarship Council; National Natural Science Foundation of China [51331006]SCI(E)EIARTICLE193-19840
Water Oxidation by the [Co4O4(OAc)4(py)4]+ Cubium is Initiated by OH– Addition
No full textThe cobalt cubium Co4O4(OAc)4(py)4(ClO4) (1A+) containing the mixed valence [Co4O4]5+ core is shown by multiple spectroscopic methods to react with hydroxide (OH-) but not with water molecules to produce O2. The yield of reaction products is stoichiometric (>99.5%): 4 1A+ + 4 OH- → O2 + 2 H2O + 4 1A. By contrast, the structurally homologous cubium Co4O4(trans-OAc)2(bpy)4(ClO4)3, 1B(ClO4)3 produces no O2. EPR/NMR spectroscopies show clean conversion to cubane 1A during O2 evolution with no Co2+ or Co3O4 side products. Mass spectrometry of the reaction between isotopically labeled µ-16O(bridging-oxo) 1A+ and 18O-bicarbonate/water shows: 1) no exchange of 18O into the bridging oxos of 1A+, and 2) 36O2 is the major product, thus requiring two OH- in the reactive intermediate. DFT calculations of solvated intermediates suggest that addition of two OH- to 1A+ via OH- insertion into Co-OAc bonds is energetically favored, followed by outer-sphere oxidation to intermediate [1A(OH)2]0. The absence of O2 production by cubium 1B3+ indicates the reactive intermediate derived from 1A+ requires gem-1,1-dihydoxo stereochemistry to perform O-O bond formation. Outer-sphere oxidation of this intermediate by 2 eq. 1A+ accounts for the final stoichiometry. Collectively, these results, and recent literature (Faraday Disc., doi:10.1039/C5FD00076A and J.Am.Chem.Soc 2015, 12865-12872) validate the [Co4O4]4+/5+ cubane core as an intrinsic catalyst for oxidation of hydroxide by an inner-sphere mechanism.This document is the Accepted Manuscript version of a Published Work that appeared in final form in Journal of the American Chemical Society, copyright © American Chemical Society after peer review and technical editing by the publisher. To access the final edited and published work see https://dx.doi.org/10.1021/jacs.5b09152Peer reviewe
Recognition scheme of the f/Im and f/Py pairings for Watson–Crick base pairs
No full text<p><b>Copyright information:</b></p><p>Taken from "Molecular recognition of DNA base pairs by the formamido/pyrrole and formamido/imidazole pairings in stacked polyamides"</p><p>Nucleic Acids Research 2005;33(3):912-921.</p><p>Published online 9 Feb 2005</p><p>PMCID:PMC549405.</p><p>© The Author 2005. Published by Oxford University Press. All rights reserved</p> Also depicted in this figure is the range of binding constants (10–10 M) for the f/Im and f/Py terminal pairings when placed adjacent to –ImPy– and –PyPy– central pairings. The gray box indicates selective binding by f/Im to C/G and Xs denote the poor match of f/Py and the C/G base pair
Estudo, por medidas de fluorescência e tensão superficial, da interação entre substâncias húmicas e pireno em meio aquoso
Full text linkTCC (graduação) - Universidade Federal de Santa Catarina, Centro de Ciências Físicas e Matemáticas, Curso de Química.As substâncias húmicas (SH) são os principais componentes da fração orgânica em águas, sedimentos e solos. São produtos da decomposição da matéria orgânica (MO) animal e vegetal, possuem elevadas massas molares com diferentes grupos funcionais e são responsáveis por processos físicos, químicos e biológicos nestes ambientes. Dentre os processos biogeoquímicos nos quais as SH estão envolvidas, está a solubilização de poluentes apolares, principalmente os HPAs (hidrocarbonetos policíclicos aromáticos) em águas naturais. Neste trabalho, foi utilizado o pireno, como modelo de HPA, para investigar a força e a natureza destas interações. As substâncias húmicas (ácidos fúlvicos – AF e ácidos húmicos – AH) estudadas provieram de solo (Horto 1 e Horto 2) e sedimento estuarino (Gran 7) e foram caracterizados por meio de análise elementar (CHNS) e infravermelho (IV), mostrando as propriedades típicas deste tipo de material. As constantes de associação (KCO) entre o pireno e as amostras de AF e AH, foram medidas pelo método de supressão de fluorescência (SF) utilizando as equações de Stern - Volmer. Os valores encontrados foram: 24,83 (AH Gran 7); 7,40 (AH Horto 1); 3,46 (AH Horto 2) e 17,22 (AF Horto 1). Para verificar se a supressão de fluorescência poderia ser consequência da inserção do pireno em microambientes tipo micelares nas soluções de SH, foram feitos experimentos utilizando um surfactante (dodecilsulfato de sódio - SDS) com concentração micelar crítica (CMC) conhecida. Os dados sugerem, que o mecanismo de supressão de fluorescência do pireno pelas SH, envolve outros fatores que não a simples inclusão do primeiro em ambientes pseudo-micelares
[[alternative]]Current Rectification with substituted aromatic amine diazonium modified electrodes and photodebromination with photosensitive cobalt complex
No full text[[abstract]]Aromatic amines can be converted to diazonium salts, and can thus be cathodically deposited on carbon electrodes. In the light of this, we prepared chemically modified electrodes (CME) with aromatic amines, such as aniline and p-terphenylamine, via the diazonium pathway, and utilized them to rectify the flow of electric current from electrodes to electrolyte solutions. Experimental results based on cyclic voltammetry (CV), electrochemical quartz-crystal-microbalance analysis (EQCM), electrochemical impedance analysis (EIS), and totally-attenuated- reflectance Infrared absorption spectral (ATR-IR) analysis indicated that the CMEs prepared in this manner seem to be free of pin holes on the electrode surface, and can, in advance, be employed to microsolvate electron mediators, like benzoquinone (BQ), vitamin K3 (VK3) and anthraquinone (AQ), for further applications, such as for current rectification.
Besides, we also attempted to mimic vitamin B12 for the dehalogenation of dibromobutane. Cobalt complexes such as tris(5-aminophenanthroline) cobalt(II) hexafluorophosphate (Co(NH2-phen)32+) show application potential in this aspect. By attaching light-absorption chromophores, like pyrene, with Co(NH2-phen)32+, we, in addition, found that the resultant derivative (denoted py-Co(NH2-phen)32+ ) can be reduced at less negative potential, ca. -0.6 V vs. Ag/AgCl under UV irradiation in DMSO, and then, cause dibromobutane (DBB) to be reductively decomposed into less toxic products.
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