370 research outputs found

    Experimental study of honeycomb SiCSi under highly concentrated solar flux: Evolution of its thermo-radiative properties

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    The material that is used in solar receivers is subjected to intense cyclic thermal stresses and extreme temperatures, which are directly dependent on the intermittence of the solar resource. These factors accelerate the ageing mechanisms and reduce the durability of the receivers because of a reduction of their thermal performance. This study presents guidelines to study the thermo-radiative properties of an absorber material that is subjected to a highly concentrated solar flux. The material was a square honeycomb SiCSi structure that is typically used in volumetric air receivers. Accelerated ageing tests were performed by means of crashing thermal treatments, in which the modulus and period of the incident flux and the boundary conditions of the material were varied. The reflectivity and absorptivity of the material were experimentally characterized before and after the thermal treatments. The measurements were performed using two different reflectometers, one monochromatic and one in the solar band; the latter can measure at ambient temperature or high temperature that is representative of the operational conditions (400-700 degrees C). However, only the solar band reflectometer working at high temperature was able to detect the evolution of the thermo-radiative properties of the material, which highlights the important role of the temperature and the wavelength. Furthermore, the thermal treatments in which the samples were water-cooled and in which the solar flux was medial more quickly accelerated the ageing mechanism of the material and reduced its absorptivity.The authors acknowledge the financial support of the research programme of the Universidad Carlos III de Madrid, 2015, which made this study possible through a mobility grant. Moreover, this work was supported by the French "Investments for the future" programme, which is managed by the National Agency for Research under contract ANR-10-LABX-22-01 by Labex SOLSTICE and by the Spanish government under the project ENE2012-34255

    Fabric phase sorptive extraction of selected steroid hormone residues in commercial raw milk followed by ultra-high-performance liquid chromatography–tandem mass spectrometry

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    Hormones in edible matrices, such as milk, are a subject of concern because of their adverse effects on the endocrine system and cell signaling and the consequent disruption of homeostasis in human consumers. Therefore, the assessment of the presence of hormones in milk as potential endocrine-disrupting compounds is warranted. However, the complexity of milk as a sample matrix and the ultra-low concentration of hormones pose significant analytical challenges. Fabric phase sorptive extraction (FPSE) has emerged as a powerful analytical technique for the extraction of emerging pollutants from complex aqueous matrices. FPSE allows for substantially simplified sample handling and short extraction and desorption times, as well as the decreased use of organic solvents. It is considered a green alternative to traditional extraction methodologies. In this work, the FPSE technique was evaluated to perform the simultaneous extraction of 15 steroid hormones from raw milk without employing any sample pretreatment steps. Clean and preconcentrated hormone solutions obtained from FPSE of raw milk were analyzed using ultra-high-performance liquid chromatography–tandem mass spectrometry to achieve low detection limits, which ranged from 0.047 to 1.242 ng·mL−1. Because of the presence of many interferents in milk, such as proteins, lipids, and sugar, the effect of fat content on the extraction procedure was also thoroughly studied. Additionally, for the first time, the effect of lactose on the extraction of steroid hormones was evaluated, and the results showed that the extraction efficiencies were enhanced in lactose-free samples. Finally, the optimized methodology was applied to commercial samples of cow and goat milk, and no measurable concentrations of the studied hormones were detected in these samples

    Conjunctival Melanoma: A New Clinical and Therapeutical Approach

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    Melanoma involving the conjunctiva is extremely rare. Graver prognosis has been reported with primary conjunctival melanoma than with their cutaneous counterparts [Collin et al.: Aust N Z J Ophthalmol 1986;14:29–34]. Among conjunctival melanomas, two significant risk factors for tumour-related death have been identified: (i) age older than 55 years and (ii) unfavourable tumour location (caruncle, cornea, fornix, palpebral conjunctiva) [Werschnik and Lommatzsch: Am J Clin Oncol 2002;25:248–255]. Here we present a rare case of lentigo maligna involving the palpebral, bulbar conjunctiva and the caruncle. We describe dermoscopic patterns observed and the use of a novel ocular melanoma therapy with topical imiquimod

    Interacción de Trichoderma harzianum Rifai y Azadirachta indica A. Juss. sobre una población de Meloidogyne spp. en plántulas de Solanum lycopersicum L.

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    El experimento se desarrolló en las áreas de investigación de la Universidad de Pinar del Río, Cuba, con el objetivo de evaluar el efecto de Trichoderma harzianum Rifai (cepa A-34) y extracto acuoso de nim (Azadirachta indica A. Juss.) sobre una población de Meloidogyne spp. en plántulas de tomate (Solanum lycopersicum L.) cultivar «PR-92». Se utilizaron 50 bolsas de polietileno con capacidad de 900 g de sustrato, que se conformó mediante una mezcla de suelo Ferralítico Amarillento Lixiviado, turba y cascarilla de arroz (70:20:10). Los tratamientos estudiados fueron: plántulas + T. harzianum + nematodos, plántulas + nim + nematodos, plántulas + T. harzianum + nim + nematodos, control (plántulas + nematodos) y control absoluto (plántulas sin inoculaciones). La inoculación de nematodos se dirigió a la rizofera, a razón de 0,5 J2-huevos por gramo de sustrato. Se produjo reducción del índice de agallamiento en 53,5%; 38,5% y 61,5% para los tratamientos donde se aplicó T. harzianum, nim y su combinación, respectivamente, con diferencias significativas con relación al control. También se lograron incrementos significativos en la longitud y el diámetro del tallo y la masa seca de las plántulas de tomate con la aplicación de T. harzianum y su combinación con extracto acuoso de nim

    Comorbidities in a sample of adults with HIV in Puerto Rico: an exploratory study.

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    Background: Puerto Rico is among the areas with the highest estimated rates of people living with HIV in the United States. Despite the epidemiologic data available, there is limited real-world information that can help understand the comorbidities of people with HIV. In this study, we describe common comorbidities among adults with HIV attending treatment clinics in Puerto Rico. Methods: An exploratory, retrospective, cross-sectional study was conducted at five HIV clinics in Puerto Rico. A random sample of medical records was reviewed. Descriptive statistics were used to summarize patient demographics, morbidity, and clinical characteristics. Multivariate analyses were conducted to explore comorbidities by age and sex. Results: A total of 250 (179 men; 71 women) medical records were reviewed. Participants\u27 mean age was 47.9 years and on average they had been living with HIV for 9 years. Most (97.6%) had at least one comorbidity. The most common comorbidities were dyslipidemia and hypertension. Men were more likely to have been diagnosed with alcohol misuse while women were more likely to have been diagnosed with obesity, human papillomavirus (HPV), hypothyroidism, and osteoporosis. Participants younger than 50 years of age were more likely to have history of alcohol misuse while older individuals (50 years and old) were more likely to have been diagnosed with dyslipidemia, hypertension, and diabetes. Adjusting by sex and age, women were more likely to have been diagnosed with obesity and depression and those older than 50 years were more likely to have had a diagnosis of dyslipidemia, hypertension, HPV, and diabetes. Conclusions: This is one of the few studies assessing comorbidities among adults with HIV in Puerto Rico, among Latino/Hispanics within the United States, and Latin America. Consistent with other studies, cardiovascular diseases are common among adults with HIV in Puerto Rico. Findings support the need for awareness and real-world evidence about comorbidities among people with HIV when implementing screenings and prescribing drugs

    Evidence for a black-hole in the X-ray transient XTE J1859+226

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    We present the results of time-resolved optical photometry and spectroscopy of the X-ray transient XTE J1859+226 (V406 Vul). Photometric observations taken during 2000 and 2008 reveals the presence of the secondary star's ellipsoidal modulation. Further photometry obtained in 2010 shows the system ~1 mag brighter than its quiescence level and the ellipsoidal modulation diluted by strong flaring activity. Spectroscopic data obtained with the 10.4-m GTC in 2010 reveals radial velocity variations of ~500 km/s over 3 h. A simultaneous fit to the photometry and spectroscopy using sinusoids to represent the secondary star's ellipsoidal and radial velocity variations, yields an orbital period of 6.58+-0.05 h and a secondary star's radial velocity semi-amplitude of K_2= 541+-70 km/s. The implied mass function is f(M)=4.5+-0.6 Msun, significantly lower than previously reported but consistent with the presence of a black hole in XTE J1859+226. The lack of eclipses sets an upper limit to the inclination of 70 degrees which yields a lower limit to the black hole mass of 5.42 Msun.Comment: Accepted for publication in MNRAS. Contains 5 pages and 4 figure

    Emergence of ceftazidime/avibactam resistance in KPC-8–producing Klebsiella pneumoniae in South America

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    Klebsiella pneumoniae is one of the so-called ESKAPE pathogens. These organisms are the main cause of nosocomial infections worldwide, causing life-threatening infections amongst critically ill and immunocompromised individuals. They are characterized by drug resistance mechanisms. Klebsiella pneumoniae carbapenemase (KPC)-producing isolates display resistance to multiple antimicrobial agents, usually including last-resort alternative options, leading to an urgent need to develop new drugs or combinations. In Argentina sequence type (ST) 258 harbouring bla KPC-2 emerged in 2010 and remained prevalent until the last few years, when the emergence of different STs such as ST25, ST11 and ST307 appeared likely to change the local epidemiology.Fil: García, J.. Universidad de Buenos Aires. Facultad de Medicina. Hospital de Clínicas General San Martín; ArgentinaFil: Nastro, Marcela. Universidad de Buenos Aires. Facultad de Medicina. Hospital de Clínicas General San Martín; ArgentinaFil: Cejas, Daniela. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad de Buenos Aires. Facultad de Farmacia y Bioquimica. Instituto de Investigaciones En Bacteriologia y Virologia Molecular; ArgentinaFil: Santana, G.. No especifíca;Fil: Mancino, M.B.. No especifíca;Fil: Hidalgo, M.. No especifíca;Fil: Maccallini, G.. No especifíca;Fil: Vay, C.. Universidad de Buenos Aires. Facultad de Medicina. Hospital de Clínicas General San Martín; ArgentinaFil: Radice, Marcela Alejandra. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad de Buenos Aires. Facultad de Farmacia y Bioquimica. Instituto de Investigaciones En Bacteriologia y Virologia Molecular; ArgentinaFil: Dabos, L.. Université Paris Sud; FranciaFil: Famiglietti, Angela María Rosa. Universidad de Buenos Aires. Facultad de Medicina. Hospital de Clínicas General San Martín; ArgentinaFil: Rodríguez, H.. Universidad de Buenos Aires. Facultad de Medicina. Hospital de Clínicas General San Martín; Argentin

    Magma emission rates fromshallow submarine eruptions using airborne thermal imaging

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    The effusion rate is the most important parameter to gatherwhen a volcanic eruption occurs, because it controls the way inwhich a lava body grows, extends and expands, influencing its dimensional properties. Calculation of lava flow volume from thermal images collected by helicopter surveys has been largely used during the last decade for monitoring subaerial effusive eruptions. However, due to the depths where volcanic activity occurs, monitoring submarine volcanic eruptions is a very difficult task. The 2011–2012 submarine volcanic eruption at El Hierro, Canary Islands, has provided a unique and excellent opportunity to monitor eruptive processes occurring on the seabed. The use of a hand-held thermal camera during daily helicopter flights allowed us to estimate for the first time the daily and total erupted magma volumes from a submarine eruption. The volume of magma emitted during this eruption has been estimated at 300 Mm3, giving an average effusion rate of ~25 m3 s−1. Thermal imagery by helicopter proved to be a fast, inexpensive, safe and reliable technique of monitoring volcanic eruptions when they occur on the shallow seabed.This research was financially supported by the projects MAKAVOL (MAC/3/C161) from the European Union MAC 2007–2013 Transnational Cooperation Program as well as from the Cabildo Insular de Tenerife. We are also grateful to the staff of El Hierro airport (AENA) for providing logistical support.Published219-2255V. Sorveglianza vulcanica ed emergenzeJCR Journalrestricte
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