7,990 research outputs found

    SMEs in Focus : Exploring the experience of micro, small and medium enterprise owners in Malta

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    Report commissioned by the Ministry for Fair Competition, Small Business and Consumers in 2011. In-depth qualitative interviews were carried out on a purposive sample of business owners (n=31) to explore the relational dynamics at the root of doing business. Analysis focuses on two key intersections across macro/micro dimensions: the interface between the State and the Individual; and also that between the Market and the Individual enterprise. Key themes: Entrepreneurial motivation; Process of Process of ‘Rationalisation’ and ‘Regulation’; Enterprise owners’ perceived burdens/assets; Influence of family and gender; Collaboration and CompetitionMinistry for Fair Competition, Small Business and Consumerspeer-reviewe

    Microwave-assisted and conventional hydrothermal carbonization of lignocellulosic waste material: comparison of the chemical and structural properties of the hydrochars

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    This study compares the chemical and structural properties of the hydrochars prepared from microwave-assisted and conventional hydrothermal carbonizations of Prosopis africana shell, a waste plant material. The preparation involved heating the raw material in de-ionized water at 200 °C for 5-20 min, and 120-240 min in the microwave and conventional oven respectively. The prepared hydrochars were characterized using the scanning electron microscope, nitrogen sorption measurement, Fourier transform infrared spectroscopy, CHN analyzer, thermogravimetric analysis, and nuclear magnetic resonance. The results showed that the microwave-assisted hydrothermal carbonization process is fast in the carbonization of the Prosopis africana shell as shown by the level of conversion attained within the short time. This study presents new data on the comparison of the hydrochars from microwave-assisted and conventional hydrothermal carbonization processes of the same lignocellulosic material in terms of their properties

    Biomass derived mesoporous carbon monoliths via an evaporation-induced self-assembly

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    Evaporation-induced self-assembly has been applied in the synthesis of crack-free mesoporous carbon monolith with good mechanical stability using a waste plant material as carbon precursor and triblock copolymer F127 as template. The carbon monolith was characterized using transmission electron microscopy, scanning electron microscopy, nitrogen adsorption–desorption measurement, X-ray diffraction and Fourier transform infrared spectroscopy. The results showed that the carbon monolith is mesoporous, has a surface area of 219 m²/g, and a narrow pore size distribution of 6.5 nm

    Microwave-assisted hydrothermal carbonization of rapeseed husk: A strategy for improving its solid fuel properties

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    Hydrothermal carbonization of a waste biomass material is a green and promising technique for improving its solid fuel properties, which does not require pretreatment procedure such as drying of the biomass. In this study, hydrothermal carbonization of rapeseed husk, a waste plant material was carried out under microwave heating and the effect of process parameters, such as reaction temperature and residence time on the mass yields and energy properties of the hydrochars was studied. The procedure involved the heating of the feedstock in deionized water in a microwave oven at temperatures of 150 to 200 °C for a specified period of time. The results indicated that the mass yields decreased, as the reaction temperature and residence time were increased, which led to improvement in the energy properties of the prepared hydrochars. The reaction was rapid within the first 20 min, and stabilized afterwards. The energy properties of the prepared hydrochars are consistent with previous studies, showing that the hydrochars have the potential of being used as solid fuel. The structural and morphological analysis carried out revealed that the feedstock was transformed during the process

    The Close Binary Fraction of Dwarf M Stars

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    We describe a search for close spectroscopic dwarf M star binaries using data from the Sloan Digital Sky Survey to address the question of the rate of occurrence of multiplicity in M dwarfs. We use a template-fitting technique to measure radial velocities from 145,888 individual spectra obtained for a magnitude-limited sample of 39,543 M dwarfs. Typically, the three or four spectra observed for each star are separated in time by less than four hours, but for ~17% of the stars, the individual observations span more than two days. In these cases we are sensitive to large-amplitude radial velocity variations on timescales comparable to the separation between the observations. We use a control sample of objects having observations taken within a four-hour period to make an empirical estimate of the underlying radial velocity error distribution and simulate our detection efficiency for a wide range of binary star systems. We find the frequency of binaries among the dwarf M stars with a < 0.4 AU to be 3%-4%. Comparison with other samples of binary stars demonstrates that the close binary fraction, like the total binary fraction, is an increasing function of primary mass

    Data report: late Miocene to early Pliocene coccolithophore and foraminiferal preservation at Site U1338 from scanning electron microscopy

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    The late Miocene to early Pliocene carbonate-rich sediments recovered at Integrated Ocean Drilling Program (IODP) Site U1338 during the Expedition 320/321 Pacific Equatorial Age Transect (PEAT) program contain abundant calcareous nanno- and microfossils. Geochemical proxies from benthic and planktonic foraminiferal and coccolithophore calcite could be very useful at this location; however, good preservation of the calcite is crucial for the proxies to be robust. Here, we evaluate the preservation of specific benthic and planktonic foraminifer species and coccolithophores in fine fraction sediment at Site U1338 using backscattered electron (topography mode) scanning electron microscopy (BSE-TOPO SEM). Both investigated foraminiferal species, Cibicidoides mundulus and Globigerinoides sacculifer, have undergone some alteration. The C. mundulus show minor evidence for dissolution, and only some specimens show evidence of overgrowth. The Gs. sacculifer show definite signs of alteration and exhibit variable preservation, ranging from fair to poor; some specimens show minor overgrowth and internal recrystallization but retain original features such as pores, spine pits, and internal testwall growth structure, whereas in other specimens the recrystallization and overgrowth disguise many of the original features. Secondary electron and BSE-TOPO SEM images show that coccolith calcite preservation is moderate or moderate to poor. Slight to moderate etching has removed central heterococcolith features, and a small amount of secondary overgrowth is also visible. Energy dispersive spectroscopy analyses indicate that the main sedimentary components of the fine fraction sediment are biogenic CaCO3 and SiO2, with some marine barite. Based on the investigations in this data report, geochemical analyses on benthic foraminifers are unlikely to be affected by preservation, although geochemical analyses on the planktonic foraminifers should be treated cautiously because of the fair to poor and highly variable preservation

    Nanotoxicity of polyelectrolyte-functionalized titania nanoparticles towards microalgae and yeast: Role of the particle concentration, size and surface charge

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    We studied the nanotoxicity of titania nanoparticles (TiOâ‚‚NPs) of various hydrodynamic diameters and crystallite sizes towards C. reinhardtii microalgae and S. cerevisiae (yeast) upon illumination with UV and visible light. The cell viability was assessed for a range of nanoparticle concentrations and incubation times. We found that bare TiOâ‚‚NPs affect the C. reinhardtii cell viability at much lower particle concentrations than for yeast. We observed an increase of the TiOâ‚‚NPs toxicity upon illumination with UV light compared with that in dark conditions due to the oxidative stress of the produced reactive oxygen species. We also found an increased TiOâ‚‚NPs nanotoxicity upon illumination with visible light which indicates that they may also interfere with the microalgae's photosynthetic system leading to decreased chlorophyll content upon exposure to TiOâ‚‚NPs. The results indicate that the larger the hydrodynamic diameter of the TiOâ‚‚NPs the lower is their nanotoxicity, with anatase TiOâ‚‚NPs generally being more toxic than rutile TiOâ‚‚NPs. We also prepared a range of polyelectrolyte-coated TiOâ‚‚NPs using a layer by-layer method and studied their nanotoxicity towards yeast and microalgae. We found that the toxicity of the coated TiOâ‚‚NPs changes with their surface charge. TiOâ‚‚NPs coated with cationic polyelectrolyte as an outer layer exhibit much higher nanotoxicity than the ones with an outer layer of anionic polyelectrolyte. TEM images of sectioned microalgae and yeast cells exposed to different polyelectrolyte-coated TiOâ‚‚NPs confirmed the formation of a significant build-up of nanoparticles on the cell surface for bare and cationic polyelectrolyte-coated TiOâ‚‚NPs. The effect comes from the increased adhesion of cationic nanoparticles to the cell walls. Significantly, coating the TiOâ‚‚NPs with anionic polyelectrolyte as an outer layer led to a reduced adhesion and much lower nanotoxicity due to electrostatic repulsion with the cell walls. This suggest a new way of making cationic TiOâ‚‚NPs safer for use in different formulations by pre-coating them with anionic polyelectrolytes. The results of this study give important insights into the various factors controlling the nanotoxicity of TiOâ‚‚NPs
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