744 research outputs found

    Intensifying glycerol steam reforming on a monolith catalyst: a reaction kinetic model

    Get PDF
    In this work, a structured monolithic catalyst has been tested under a wide range of conditions (partial pressure, residence time, temperature and time-on-stream), with the aim of modeling its kinetic behavior and assessing its economic and upscaling potential. We have developed a sequential model to help us interpret both main trends and salient features. Unexpected behavior was found for certain parameter values, which led us to consider kinetic parasitic effects such as mass or heat transfer limitations. By independently invoking these effects, a conciliatory view of the results observed could not be reached. A combined explanation may prove successful, although overfitting could not be ruled out at this point. More importantly, however, the observed salient features of this stable and selective monolith catalyst may hold potential for process intensification of glycerol steam reforming, thus contributing to a more sustainable industry.Ministerio de Economía y Competitividad ENE2013-47880-C3-2-R, ENE2015-66975-C3-2-

    First observations of the X-ray transient EXO 2030+375 with IBIS/ISGRI

    Get PDF
    We present a first INTEGRAL observation of the 42s transient X-ray pulsar EXO 2030+375 with IBIS/ISGRI. The source was detected during Cyg X-1 observations in December 2002. We analyzed observations during the outburst period from 9 to 21 December 2002 with a total exposure time of ~770 kiloseconds. EXO 2030+375 was almost always detected during single ~30 minute exposures in the 18-45 energy bands. The source light curve shows the characteristic outburst shape observed in this source.Comment: 4 pages, 3 figures (1 in CMYK color), accepted by Astronomy and Astrophysics, INTEGRAL special issue, 200

    Antifungal hydroxypropyl methylcellulose (HPMC)-lipid composite edible coatings and modified atmosphere packaging (MAP) to reduce postharvest decay and improve storability of ‘Mollar de Elche’ pomegranates

    Get PDF
    Pomegranate exhibits important postharvest quality losses that limit its storage potential, caused mainly by weight loss, chilling injury and fungal diseases. In this work, we evaluated the effect of novel hydroxypropyl methylcellulose (HPMC) edible coatings (ECs) formulated with three different lipids (beeswax (BW), carnauba wax, and glycerol monostearate), as hydrophobic components, and two different GRAS salts (potassium bicarbonate (PBC) and sodium benzoate (SB)), as antifungal ingredients, to control weight loss and natural fungal decay of ‘Mollar de Elche’ pomegranates during storage at 20◦C. Afterwards, selected antifungal ECs and commercial modified atmosphere packaging (MAP) films were assayed alone or in combination to control natural decay and preserve fruit quality of pomegranates stored at 5◦C for 4 months plus 1 week at 20◦C. Results showed that ECs amended with SB reduced pomegranate latent infections caused by Botrytis cinerea and wound diseases caused by Penicillium spp. Moreover, MAP technologies were confirmed as an efficient mean to preserve freshness, prevent fruit shriveling and rind browning, and reduce fungal decay, thus extending storage life of pomegranates. The combination HPMC-BW-SB + MAP was the most promising treatment as it reduced weight loss and decay, without negatively affecting the fruit physicochemical and sensory quality

    INTEGRAL observations of the Be/X-ray binary EXO 2030+375 during outburst

    Full text link
    We present a type-I outburst of the high-mass X-ray binary EXO 2030+375, detected during INTEGRAL's Performance and Verification Phase in December 2002 (on-source time about 10e+06 seconds). In addition, six more outbursts have been observed during INTEGRAL's Galactic Plane Scans. X-ray pulsations have been detected with a pulse period of 41.691798+-0.000016 s. The X-ray luminosity in the 5-300 keV energy range was 9.7*10e+36 erg/s, for a distance of 7.1 kpc. Two unusual features were found in the light curve, with an initial peak before the main outburst and another possible spike after the maximum. RXTE observations confirm only the existence of the initial spike. Although the initial peak appears to be a recurrent feature, the physical mechanisms producing it and the possible second spike are unknown. Moreover, a four-day delay between periastron passage and the peak of the outburst is observed. We present for the first time a 5-300 keV broad-band spectrum of this source. It can be modelled by the sum of a disk black body (kT_bb~8 keV) with either a power law model with Gamma=2.04+-0.11 keV or a Comptonized component (spherical geometry, kT_e=30 keV, tau=2.64, kT_W=1.5 keV).Comment: 10 pages, 11 figures, to be published in A&

    Treatment of subclinical hyperthyroidism: Effect on body composition

    Get PDF
    Background: subclinical hyperthyroidism (SHT) is associated with harmful effects on cardiovascular system, bone metabolism and progression to clinical hyperthyroidism. Loss of weight is a common fact in patients with clinical hyperthyroidism and of particular relevance in elderly patients. Objective: to assess changes in body composition after radioiodine therapy for SHT due to toxic nodular goiter. Subjects and methods: prospective controlled cohort study. Patients with persistent SHT due to toxic nodular goiter were purposed to receive treatment with radioiodine (treatment group) or to delay treatment until the study was over (control group). All treated patients received 555 MBq of 131I. Body composition (lean mass, fat mass and bone mineral content) was determined by dual-energy X-ray absorptiometry (DEXA) at baseline and 12 months after. Results: twenty-nine patients were studied (age 69.5 ± 11.5; 75.9% women; BMI 27.1 ± 5.7 kg/m²; serum thyrotropin (TSH) 0.20 ± 0.21 µUI/mL; serum free thyroxine (T4) 1.01 ± 0.19 ng/dL), 17 belonging to the treatment group and 12 to the control group. Study groups were comparable, although there was a trend for the treatment group to have more fat mass. No longitudinal changes in body composition were noted in either group, except for a trend to gain fat mass. However, when individuals with age > 65 years were selected, only patients who received radioiodine therapy showed a significant increase in body weight (from 64.1 ± 10.0 to 66.9 ± 9.2 kg), BMI (from 27.3 ± 4.8 to 28.7 ± 4.5 kg/m²), fat mass (from 26.1 ± 8.5 to 27.8 ± 7.9 kg), lean mass (from 36.3 ± 0.4 to 37.4 ± 0.4 kg) and skeletal muscle mass index (SMI) (from 6.0 ± 0.6 to 6.3 ± 0.6 kg/m²). Conclusions: treatment of SHT has impact on body composition in subjects older than 65 years. Weight gain reflects increases in fat and, more interestingly, in lean mass

    Probing stellar winds and accretion physics in high-mass X-ray binaries and ultra-luminous X-ray sources with LOFT

    Get PDF
    This is a White Paper in support of the mission concept of the Large Observatory for X-ray Timing (LOFT), proposed as a medium-sized ESA mission. We discuss the potential of LOFT for the study of high-mass X-ray binaries and ultra-luminous X-ray sources. For a summary, we refer to the paper.Comment: White Paper in Support of the Mission Concept of the Large Observatory for X-ray Timing. (v2 few typos corrected

    Two years of monitoring Supergiant Fast X-ray Transients with Swift

    Full text link
    We present two years of intense Swift monitoring of three SFXTs, IGR J16479-4514, XTE J1739-302, and IGR J17544-2619 (since October 2007). Out-of-outburst intensity-based X-ray (0.3-10keV) spectroscopy yields absorbed power laws with by hard photon indices (G~1-2). Their outburst broad-band (0.3-150 keV) spectra can be fit well with models typically used to describe the X-ray emission from accreting NSs in HMXBs. We assess how long each source spends in each state using a systematic monitoring with a sensitive instrument. These sources spend 3-5% of the total in bright outbursts. The most probable flux is 1-2E-11 erg cm^{-2} s^{-1} (2-10 keV, unabsorbed), corresponding to luminosities in the order of a few 10^{33} to 10^{34} erg s^{-1} (two orders of magnitude lower than the bright outbursts). The duty-cycle of inactivity is 19, 39, 55%, for IGR J16479-4514, XTE J1739-302, and IGR J17544-2619, respectively. We present a complete list of BAT on-board detections further confirming the continued activity of these sources. This demonstrates that true quiescence is a rare state, and that these transients accrete matter throughout their life at different rates. X-ray variability is observed at all timescales and intensities we can probe. Superimposed on the day-to-day variability is intra-day flaring which involves variations up to one order of magnitude that can occur down to timescales as short as ~1ks, and whichcan be explained by the accretion of single clumps composing the donor wind with masses M_cl~0.3-2x10^{19} g. (Abridged)Comment: Accepted for publication in MNRAS. 17 pages, 11 figures, 8 table
    corecore