182 research outputs found
Tracing deep fluid source contribution to groundwater in an active seismic area (central Italy): A combined geothermometric and isotopic (δ13C) perspective
An understanding of the origin and migration pathways of geofluids in an active seismic area is of paramount importance in terms of societal challenges such as mitigation of seismic hazards. This study investigates the relationship between the stable isotope ratio 13C/12C of deep CO2 and geothermometry in selected groundwater samples located close to extensional faults in central Italy. The temperature range is inferred from an equation based on the Na/Li ratio and chemical geothermal modelling: 113–130 °C. Globally, the calculated temperature range agrees with that resulting from deep boreholes in the Northern Apennines. An alternative method is also included to better evaluate the difference in isotopic composition between the aqueous and gaseous δ13C(CO2) at deep condition. A review of previously published data shows that monitoring of the isotopic composition of the dissolved inorganic carbon (DIC) in springs fed by meteoric origin located in seismically active areas must take into account mass and isotopic balance to correctly evaluate the component, and the role, of deep fluid during seismic events. In particular, the coupled (and corrected) isotope and geothermometrical monitoring of the springs could help to distinguish between deep gas or deep fluid contributions to shallow aquifers. The results of this study indicate that faults play a crucial role in controlling the migration of crustal fluids. In addition, they reveal that possible evaluation of potential seismic precursors mandatorily requires a long period of monthly monitoring
In-doped Sb nanowires grown by MOCVD for high speed phase change memories
We investigated the Phase Change Memory (PCM) capabilities of In-doped Sb nanowires (NWs) with diameters of (20-40) nm, which were self-assembled by Metalorganic Chemical Vapor Deposition (MOCVD) via the vapor-liquid-solid (VLS) mechanism. The PCM behavior of the NWs was proved, and it was shown to have relatively low reset power consumption (~ 400 μW) and fast switching capabilities with respect to standard Ge-Sb-Te based devices. In particular, reversible set and reset switches by voltage pulses as short as 25 ns were demonstrated. The obtained results are useful for understanding the effects of downscaling in PCM devices and for the exploration of innovative PCM architectures and materials. Keywords: Phase change memories, Nanowires, MOCVD, In-Sb, TEM, XR
In-doped Sb nanowires grown by MOCVD for high speed phase change memories
We investigated the Phase Change Memory (PCM) capabilities of In-doped Sb nanowires (NWs) with diameters of (20-40) nm, which were self-assembled by Metalorganic Chemical Vapor Deposition (MOCVD) via the vapor-liquid-solid (VLS) mechanism. The PCM behavior of the NWs was proved, and it was shown to have relatively low reset power consumption (~ 400 μW) and fast switching capabilities with respect to standard Ge-Sb-Te based devices. In particular, reversible set and reset switches by voltage pulses as short as 25 ns were demonstrated. The obtained results are useful for understanding the effects of downscaling in PCM devices and for the exploration of innovative PCM architectures and materials
Geothermal potential and origin of natural thermal fluids in the northern Lake Abaya area (Main Ethiopian Rift, East Africa).
Protective Mechanical Ventilation during General Anesthesia for Open Abdominal Surgery Improves Postoperative Pulmonary Function
BACKGROUND:: The impact of intraoperative ventilation on postoperative pulmonary complications is not defined. The authors aimed at determining the effectiveness of protective mechanical ventilation during open abdominal surgery on a modified Clinical Pulmonary Infection Score as primary outcome and postoperative pulmonary function. METHODS:: Prospective randomized, open-label, clinical trial performed in 56 patients scheduled to undergo elective open abdominal surgery lasting more than 2 h. Patients were assigned by envelopes to mechanical ventilation with tidal volume of 9 ml/kg ideal body weight and zero-positive end-expiratory pressure (standard ventilation strategy) or tidal volumes of 7 ml/kg ideal body weight, 10 cm H2O positive end-expiratory pressure, and recruitment maneuvers (protective ventilation strategy). Modified Clinical Pulmonary Infection Score, gas exchange, and pulmonary functional tests were measured preoperatively, as well as at days 1, 3, and 5 after surgery. RESULTS:: Patients ventilated protectively showed better pulmonary functional tests up to day 5, fewer alterations on chest x-ray up to day 3 and higher arterial oxygenation in air at days 1, 3, and 5 (mmHg; mean \ub1 SD): 77.1 \ub1 13.0 versus 64.9 \ub1 11.3 (P = 0.0006), 80.5 \ub1 10.1 versus 69.7 \ub1 9.3 (P = 0.0002), and 82.1 \ub1 10.7 versus 78.5 \ub1 21.7 (P = 0.44) respectively. The modified Clinical Pulmonary Infection Score was lower in the protective ventilation strategy at days 1 and 3. The percentage of patients in hospital at day 28 after surgery was not different between groups (7 vs. 15% respectively, P = 0.42). CONCLUSION:: A protective ventilation strategy during abdominal surgery lasting more than 2 h improved respiratory function and reduced the modified Clinical Pulmonary Infection Score without affecting length of hospital stay
Dating of the GV7 East Antarctic ice core by high-resolution chemical records and focus on the accumulation rate variability in the last millennium
Valores de referência para carboxiemoglobina
INTRODUCTION: The reference values (RV) of biological indicators are used in the interpretation of the results of such indicators in individuals occupationally exposed to chemical agents. The Brazilian Group for the Establishment of Reference Values has worked on these definitions for the purpose of establishing RVs for several bioindicators in various regions of the country. In the present study, the RV for carboxyhemoglobin (COHb) was determined for the South of Minas Gerais. MATERIAL AND METHOD: The COHb was analyzed by the Beutler and West (1984) spectrophotometric method, optimized in our laboratory. In all the samples, analyses of some biochemical and hematological parameters were made to evaluate the health condition of a population of 200 volunteer non-smokers occupationally not exposed to CO. Each individual answered a questionnaire to obtain data pertinent to the interpretation of the results. The reference values were expressed as mean values ± standard deviation, with a 95% confidence interval, and an upper reference value. The statistical distribution of the results was made so as to enable comparisons between the results of groups of workers, rather than individual evaluations, to be made. RESULTS AND CONCLUSION: The mean value ± standard deviation was 1.0% ± 0.75; the 95% confidence interval was 0,9 - 1.1% and the upper reference value was 2.5%. By the t Student test (p < 0.05), no difference was detected between the values related to sex, age or ingestion of alcoholic beverages. The reference values obtained were close to those reported for others countries.INTRODUÇÃO: Os valores de referência de indicadores biológicos são utilizados como parâmetros para interpretação de resultados de valores obtidos em indivíduos expostos ocupacionalmente aos agentes químicos. O Grupo Brasileiro para Estabelecimento dos Valores de Referência tem se dedicado a estas determinações objetivando estabelecer valores de referência para os diferentes bioindicadores em diversas regiões do País. Determinaram-se os valores de referência para a carboxiemoglobina (COHb) no Sul de Minas Gerais. MATERIAL E MÉTODO: A COHb foi analisada pelo método espectrofométrico, otimizado no laboratório de análises toxicológicas. Em todas as amostras também foram realizadas análises de alguns parâmetros bioquímicos e hematológicos para atestar o estado de saúde da população, constituída de 200 voluntários não-fumantes e não-expostos, por motivo profissional, ao monóxido de carbono. Cada indivíduo respondeu um questionário para levantamento de dados relevantes à interpretação dos resultados. Os valores de referência foram expressos em termos da média ± desvio-padrão, intervalo de confiança 95% e valor de referência superior. A distribuição estatística dos resultados obtidos foi realizada para possibilitar sua comparação com grupos de trabalhadores, preferentemente à avaliação individual. RESULTADOS E CONCLUSÕES: O valor médio ± desvio-padrão para a carboxiemoglobina foi de 1,0 % ± 0,75; o intervalo de confiança 95%, entre 0,9 e 1,1 % e o valor de referência superior, de 2,5%. Através do teste t de Student (p < 0,05) não foi detectada diferença nos valores de acordo com o sexo, idade ou uso de bebidas alcoólicas. Os valores de referência encontrados foram similares aos reportados em outros países
Catastrophic NAD+ Depletion in Activated T Lymphocytes through Nampt Inhibition Reduces Demyelination and Disability in EAE
Nicotinamide phosphoribosyltransferase (Nampt) inhibitors such as FK866 are potent inhibitors of NAD+ synthesis that show promise for the treatment of different forms of cancer. Based on Nampt upregulation in activated T lymphocytes and on preliminary reports of lymphopenia in FK866 treated patients, we have investigated FK866 for its capacity to interfere with T lymphocyte function and survival. Intracellular pyridine nucleotides, ATP, mitochondrial function, viability, proliferation, activation markers and cytokine secretion were assessed in resting and in activated human T lymphocytes. In addition, we used experimental autoimmune encephalomyelitis (EAE) as a model of T-cell mediated autoimmune disease to assess FK866 efficacy in vivo. We show that activated, but not resting, T lymphocytes undergo massive NAD+ depletion upon FK866-mediated Nampt inhibition. As a consequence, impaired proliferation, reduced IFN-γ and TNF-α production, and finally autophagic cell demise result. We demonstrate that upregulation of the NAD+-degrading enzyme poly-(ADP-ribose)-polymerase (PARP) by activated T cells enhances their susceptibility to NAD+ depletion. In addition, we relate defective IFN-γ and TNF-α production in response to FK866 to impaired Sirt6 activity. Finally, we show that FK866 strikingly reduces the neurological damage and the clinical manifestations of EAE. In conclusion, Nampt inhibitors (and possibly Sirt6 inhibitors) could be used to modulate T cell-mediated immune responses and thereby be beneficial in immune-mediated disorders
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