388 research outputs found

    Vacuum ultraviolet photoabsorption of prime ice analogues of Pluto and Charon

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    Here we present the first Vacuum UltraViolet (VUV) photoabsorption spectra of ice analogues of Pluto and Charon ice mixtures. For Pluto the ice analogue is an icy mixture containing nitrogen (N2), carbon monoxide (CO), methane (CH4) and water (H2O) prepared with a 100:1:1:3 ratio, respectively. Photoabsorption of icy mixtures with and without H2O were recorded and no significant changes in the spectra due to presence of H2O were observed. For Charon a VUV photoabsorption spectra of an ice analogue containing ammonia (NH3) and H2O prepared with a 1:1 ratio was recorded, a spectrum of ammonium hydroxide (NH4OH) was also recorded. These spectra may help to interpret the P-Alice data from New Horizons

    Qualitative observation of reversible phase change in astrochemical ethanethiol ices using infrared spectroscopy

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    Here we report the first evidence for a reversible phase change in an ethanethiol ice prepared under astrochemical conditions. InfraRed (IR) spectroscopy was used to monitor the morphology of the ice using the Ssingle bondH stretching vibration, a characteristic vibration of thiol molecules. The deposited sample was able to switch between amorphous and crystalline phases repeatedly under temperature cycles between 10 K and 130 K with subsequent loss of molecules in every phase change. Such an effect is dependent upon the original thickness of the ice. Further work on quantitative analysis is to be carried out in due course whereas here we are reporting the first results obtained

    Vacuum ultraviolet photoabsorption spectra of nitrile ices for their identification on Pluto

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    Icy bodies, such as Pluto, are known to harbor simple and complex molecules. The recent New Horizons flyby of Pluto has revealed a complex surface composed of bright and dark ice surfaces, indicating a rich chemistry based on nitrogen (N2), methane (CH4), and carbon monoxide (CO). Nitrile (CN) containing molecules such as acetonitrile (CH3CN), propionitrile (CH3CH2CN), butyronitrile (CH3CH2CH2CN), and isobutyronitrile ((CH3)2CHCN) are some of the nitrile molecules that are known to be synthesized by radiative processing of such simple ices. Through the provision of a spectral atlas for such compounds we propose that such nitriles may be identified from the ALICE payload on board New Horizons</i

    Techno-economic efficiency of marine fisheries in Gulf of Mannar Biosphere Reserve, India

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    Capture marine fisheries play a significant role in social, cultural, and economic dimensions of Indian capture fisheries that contributes to the blue growth strategies. Here the small-scale fisheries (SSF) constitute about 60 % and remaining 40 % large-scale fishing fleets (LSF). In this study, we have highlighted the techno-economic key indicators and technical efficiency of SSF and LSF of Gulf of Mannar Biosphere Reserve, India using Cobb-Douglas function, and Data Envelopment Analysis. The technical efficiency was slightly higher in SSF (TE = 0.961) with better quantity of fish produced per litre of fuel (5.05 kg) compared to the LSF (TE = 0.951). The labour efficiency such as value (87.56)andquantityoffishproducedperday(83.39kg)wasgreaterinLSFthantheSSF(87.56) and quantity of fish produced per day (83.39 kg) was greater in LSF than the SSF (7.07 and 14.26 kg, respectively). Though production cost was higher for LSF, the better gross revenue of 658.27wasgeneratedthanSSF(658.27 was generated than SSF (42.41) and it mainly related to higher engine power (150 – 200 hp) and longer fishing ground distance from the shore (117.50 km) for LSF than SSF (9.9 to 25 hp and 48.80 km, respectively). Results of the present study suggest that there is limited scope to improve the technical efficiency of the fishing fleet since both were operated at better efficiency conditions. However, the lower gross revenue per trip in SSF can be improved and higher production cost in LSF can be minimized by improving the performance of the fishing fleets in Biosphere Reserve

    A comparison between fine-grained and nanocrystalline electrodeposited Cu-Ni films. Insights on mechanical and corrosion performance

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    This is the author's version of a work that was accepted for publication in Surface & coating technology. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published in Surface & coating technology, Vol. 205, Núm. 23-24 (Sep 2011), p. 2585-5293 DOI 10.1016/j.surfcoat.2011.05.047Cu1−x-Nix (0.43 ≤ x ≤ 1.0) films were electrodeposited from citrate-sulphate baths at different current densities onto Cu/Ti/Si (100) substrates with the addition of saccharine as a grain-refining agent. The Cu-Ni alloy films produced from saccharine-free baths were fine-grained (crystallite size of ~400 nm). The addition of saccharine to the electrolytic solution induced a dramatic decrease in crystal size (down to ~27 nm) along with a reduction in surface roughness. Although the effect of saccharine on pure Ni films was less obvious, significant changes were observed due to the presence of saccharine in the bath during the alloying of Cu with Ni. Compared to fine-grained Cu-Ni films, the nanocrystalline films exhibited lower microstrains and a larger amount of stacking faults as observed by X-ray diffraction. These features enhance the mechanical properties of the Cu-Ni alloys, making the nanocrystalline Cu-Ni films superior to both the corresponding fine-grained films and pure Ni films. In particular, hardness in fine-grained films varied from 4.2 (x=0.43) to 5.4 GPa (x=0.86), whereas hardness varied between 6.7 and 8.2 GPa for nanocrystalline films of similar composition. In addition, wear resistance and elastic recovery were enhanced. Nanostructuring did not significantly affect corrosion resistance of Cu-Ni alloys in chloride media. Although the corrosion potential shifted slightly towards more negative values, the corrosion current density decreased, thereby making the electrodeposition nanostructuring process an effective tool to improve the overall properties of the Cu-Ni system

    Localized electrochemical deposition of porous Cu-Ni microcolumns: insights into the growth mechanisms and the mechanical performance

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    Cu-rich Cu-Ni alloy microcolumns (11-35 at% Ni) with large porosity degree were grown by localized electrochemical deposition (LECD) at voltages of 6.5 and 7.0 V. In turn, conventional electrodeposition was used to deposit fully-compact Cu-Ni films with analogous Ni/Cu ratios from a similar citrate-containing electrolytic solution. The localized supply rate of the predominant Cu(II) and Ni(II) electroactive species in the LECD microregion was calculated assuming both large and small concentration gradients. A shortage of Cu(II) at the cathode surface is mainly responsible for the development of porosity in the microcolumns, which directly affects mechanical performance, specifically nanoindentation hardness and Young's modulus. From nanoindentation experiments, a relative microcolumn density ranging between 14 and 20% was determined. These values indicate the current efficiency of the LECD process and can be used to calculate the consumption rates associated with metal cation electroreduction

    Tailoring the physical properties of electrodeposited CoNiReP alloys with large Re content by direct, pulse, and reverse pulse current techniques

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    This is the author's version of a work that was accepted for publication in Electrochimica acta. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published in Electrochimica acta, [96,(2013)] DOI10.1016/j.electacta.2013.02.077)The composition, surface morphology and structure of CoNiReP alloy films with large Re content (up to 27 at%), obtained in a citrate-glycine based electrolyte have been studied as a function of the electrodeposition technique. Direct current (DC), pulse plating (PP) and reverse pulse plating (RPP) were considered with cathodic current densities from −50 mA cm−2 to −250 mA cm−2. The mechanical and magnetic properties have been analyzed and the data obtained has been correlated with composition and crystallographic structure. For values of j (DC), jon (PP) and jc (RPP) below −100 mA cm−2, Co-rich, P-containing deposits are obtained. Beyond these current densities, both the quantities of Ni and Re increase simultaneously at the expense of Co and P, the latter virtually falling to zero. The highest Re percentage (25-27 at%) was achieved in both PP and RPP conditions at a cathodic pulse of −250 mA cm−2. All the films were either entirely nanocrystalline in nature or partially amorphous. Hardness values as high as 9.2 GPa have been found in PP plated Co64Ni18Re18 deposits. Besides the large hardness, the incorporation of Re in the films leads to high elastic recovery values. The magnetic character of the deposits ranges from soft to semi-hard ferromagneti

    Vacuum ultraviolet and infrared spectra of condensed methyl acetate on cold astrochemical dust analogs

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    Following the recent report of the first identification of methyl acetate (CH3COOCH3) in the interstellar medium (ISM) we have carried out Vacuum UltraViolet (VUV) and InfraRed (IR) spectroscopy studies on methyl acetate from 10 K until sublimation in an ultrahigh vacuum (UHV) chamber simulating astrochemical conditions. We present the first VUV and IR spectra of methyl acetate relevant to ISM conditions. Spectral signatures clearly showed molecular reorientation to have started in the ice by annealing the amorphous ice formed at 10 K. An irreversible phase change from amorphous to crystalline methyl acetate ice was found to be between 110 K and 120 K

    Standardization of sample collection, isolation and analysis methods in extracellular vesicle research

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    The emergence of publications on extracellular RNA (exRNA) and extracellular vesicles (EV) has highlighted the potential of these molecules and vehicles as biomarkers of disease and therapeutic targets. These findings have created a paradigm shift, most prominently in the field of oncology, prompting expanded interest in the field and dedication of funds for EV research. At the same time, understanding of EV subtypes, biogenesis, cargo and mechanisms of shuttling remains incomplete. The techniques that can be harnessed to address the many gaps in our current knowledge were the subject of a special workshop of the International Society for Extracellular Vesicles (ISEV) in New York City in October 2012. As part of the &#x201C;ISEV Research Seminar: Analysis and Function of RNA in Extracellular Vesicles (evRNA)&#x201D;, 6 round-table discussions were held to provide an evidence-based framework for isolation and analysis of EV, purification and analysis of associated RNA molecules, and molecular engineering of EV for therapeutic intervention. This article arises from the discussion of EV isolation and analysis at that meeting. The conclusions of the round table are supplemented with a review of published materials and our experience. Controversies and outstanding questions are identified that may inform future research and funding priorities. While we emphasize the need for standardization of specimen handling, appropriate normative controls, and isolation and analysis techniques to facilitate comparison of results, we also recognize that continual development and evaluation of techniques will be necessary as new knowledge is amassed. On many points, consensus has not yet been achieved and must be built through the reporting of well-controlled experiments
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