1,571 research outputs found

    Studies on the V<SUB>2</SUB>O<SUB>5</SUB>-TiO<SUB>2</SUB> system part 1 : Thermoelectric power and electrical conductivity

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    The thermoelectric power and the resistivity of V2O5- TiO2 mixtures over ranges of composition and temperature from 20° to 500° in air have been measured, The mixtures were obtained by coprecipitation of aqueous solutions of NH4VO3 and TiCl4. calcined during 90 h at 550° and then sintered. Resistances were measured by the four points method. At the VO5/2 35–100% M range, the activation energies for conductivity change from 0,36 to 0.62eV, while for the thermoelectric power they change from 0,18 to 0.24eV. It can be assumed from these values that the conduction mechanism over this concentration range is due to the “hopping” of small polarons, arising principally, from the presence of V4+ ions. In the samples with a high TiO2 content, the activation energies for conductivity were 0.82 and 0.36eV, for the different samples. From the variation of thermoelectric power with temperature, it can be assumed that the ionization energy of the donors centers lies at 0.83eV under the conducting band. A mechanism for band conduction is inferred from the results, being the V4+ donating centers and the V5+ receptive centers.Centro de Investigación y Desarrollo en Ciencias AplicadasConsejo Nacional de Investigaciones Científicas y TécnicasComisión de Investigaciones Científicas de la provincia de Buenos Aire

    Determination of propofol by GC/MS and fast GC/MS-TOF in two cases of poisoning

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    Two cases of suspected acute and lethal intoxication caused by propofol were delivered by the judicial authority to the Department of Sciences for Health Promotion and Mother-Child Care in Palermo, Sicily. In the first case a female nurse was found in a hotel room, where she lived with her mother; four 10 mg/mL vials and two 20 mg/mL vials of propofol were found near the decedent along with syringes and needles. In the second case a male nurse was found in the operating room of a hospital, along with a used syringe. In both cases a preliminary systematic and toxicological analysis indicated the presence of propofol in the blood and urine. As a result, a method for the quantitative determination of propofol in biological fluids was optimized and validated using a liquid-liquid extraction protocol followed by GC/MS and fast GC/MS-TOF. In the first case, the concentration of propofol in blood was determined to be 8.1 \u3bcg/mL while the concentration of propofol in the second case was calculated at 1.2 \u3bcg/mL. Additionally, the tissue distribution of propofol was determined for both cases. Brain and liver concentrations of propofol were, respectively, 31.1 and 52.2 \u3bcg/g in Case 1 and 4.7 and 49.1 \u3bcg/g in Case 2. Data emerging from the autopsy findings, histopathological exams as well as the toxicological results aided in establishing that the deaths were due to poisoning, however, the manner of death in each were different: homicide in Case 1 and suicide in Case 2

    Fire and climate: Biomass burning recorded in ice and lake cores

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    Human activities including fossil fuel burning are currently altering the global climate system at rates faster than ever recorded in geologic time. Biomass burning causes carbon dioxide emissions equal to 50% of those from fossil-fuel combustion and so are highly likely to influence future climate change. However, aerosols continue to be one of the least understood aspects of the modern climate system and even less is known about their past influence. Ice and lake core proxy records provide quantifiable data on past fire regimes across most spatial and temporal scales. Some monosaccharide anhydrides such as levoglucosan, mannosan and galactosan are used as specific molecular markers for biomass burning as they can only be produced by combustion processes at temperatures greater than 300 °C and are present in both ice and lake cores. Other paleofire tracers such as microcharcoal, polycyclic aromatic hydrocarbons, and pollen records augment the fire history derived at single sites or across regions. As both pyrochemical and climate parameters are determined from the same depth and time within the ice or sediment matrix, the multi-proxy nature of ice and lake cores presents an ideal material to investigate the links between fires and climate change

    Project Management at NASA Kennedy Space Center

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    A year-round measurement of water-soluble trace and rare earth elements in arctic aerosol: Possible inorganic tracers of specific events

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    This study presents the year-round variability of the water-soluble fraction of trace elements (wsTE) and rare earth elements (wsREE) among size segregated airborne particulate matter samples collected at Ny-Ă… lesund in the Svalbard Archipelago from 26 February 2018 to 26 February 2019. Six different aerosol dimensional fractions were collected using a multi-stage Andersen impactor to better understand local and global circulation with the aim of disentangling the source of inorganic tracers from specific natural or anthropogenic sources. The wsTE and wsREE content, especially in the finest fractions in remote areas, is primarily related to long-range transport and it gives valuable information on (1) the global circulation, (2) the natural sources and (3) the contribution of human activities to aerosol composition. A Factor Analysis was applied to the dataset, including levoglucosan and methanesulfonic acid (MSA), to assess the possibility of using certain inorganic tracers as indicators of specific transport events or circulation regimes. We also investigate back-trajectories to determine potential source areas

    CO2-assisted hydrolytic hydrogenation of cellulose and cellulose-based waste into sorbitol over commercial Ru/C

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    A single-step protocol was developed for the hydrolytic hydrogenation of microcrystalline cellulose into sorbitol over commercial carbon-supported Ru, in the presence of gaseous CO2 as an acid source and molecular hydrogen as a reductant. Under these conditions, cellulose was first hydrolysed to glucose by reversibly formed carbonic acid in water and then instantaneously hydrogenated on Ru/C. By tuning the reaction parameters, such as temperature, time and the relative pressure of CO2 and hydrogen gas, cellulose was fully converted at 220 &amp; DEG;C in 18 h under 30 and 40 bar of H-2 and CO2, respectively, with a sorbitol yield of 81%. Blank experiments revealed that without a catalyst and hydrogen, the reaction exhibited &lt;5% conversion and glucose was the only detected product when the reaction was performed under CO2 pressure. XRD measurements on CO2-treated cellulose surprisingly revealed no noticeable changes in the crystallinity index (&lt;10% with respect to microcrystalline cellulose), suggesting that hydrolytic hydrogenation took place on crystalline, not amorphous, cellulose. Furthermore, not only several cellulosic feedstocks, including filter paper, cotton wool, and cotton fiber, but also typical cellulose-based wastes such as a cardboard pizza box were also tested and under the optimized conditions sorbitol was obtained with yields ranging from 56% up to 72% in all cases. No less significant was the Ru/C catalyst stability, which could be recycled at least six times without any noticeable activity loss

    The psychopathology of body image in orthorexia nervosa

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    The human body has a complex meaning and role in everybody\u2019s life and experience. Body image has two main components: body percept (the internal visual image of body shape and size) and body concept (the level of satisfaction with one\u2019s body), whose specific alterations may lead to different conditions, such as overestimation of one\u2019s own body dimensions, negative feelings and thoughts towards the body, body avoidance and body checking behavior. Moreover, body dissatisfaction can be associated with a variety of other mental health and psychosocial conditions, but only a few studies have explored the body image construct in orthorexia nervosa (ON). ON is a condition characterized by concern and fixation about healthy eating, with mixed results available in the literature about the presence of body image disorders. The aim of this manuscript is to present the main findings from the literature about the psychopathology of body image in ON. Summarizing, while theoretically the presence of body image disturbances should help clinicians to differentiate ON from eating disorders, further research is needed to confirm this finding. It is not clear whether the body image disorder in ON depends on an altered body percept or body concept, and the relationship between the disordered eating behavior and body image disorder still needs to be disentangled. Further studies regarding the relationship between ON and body image could be helpful to better understand the relevance of body image as a transdiagnostic factor and its potential value as target for treatment intervention

    Breast cancer and communication: Monocentric experience of a self-assessment questionnaire

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    Background: The communication of the diagnosis of breast cancer induces to the patient a strong psychological trauma. Radiologists are at the forefront of communicating, either for a biopsy or the probable diagnosis of malignancy. This is a complex task, which requires the knowledge and application of correct “communicative models”, among which the SPIKES protocol rep-resents a fundamental reference. Design and methods: 110 patients, with a history of breast cancer, filled out a questionnaire consisting of six questions: five aimed at defining communication compliance with the SPIKES protocol, the sixth, consisting of six feelings, aimed at the knowledge of the next emotional state. Results: Regarding compliance with various “strategic points” of the SPIKES protocol, questionnaires show that 70% of patients reported no omissions, while the remaining 30% reported omissions relatively to perception (56%), emotions (23%), setting (13%), knowledge (6%) and invitation (2%). The results showed the existence of a correlation between the final emotional state and the correct application of the SPIKES protocol; in fact, patients who reacted with a positive final emotional state-reported greater adherence to the strategic points of the SPIKES protocol. Conclusions: In healthcare, knowing the communicative compliance of a team in giving “bad news” is fundamental, especially in breast cancer. The SPIKES protocol is recognized by the Literature as a fundamental reference able to affect “positively” the emotional state of patients. The proposed questionnaire is a valid tool to identify the weak points of communication and related criticalities, to improve clinical practice
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