96 research outputs found
A crude monte carlo analysis for treating the influence of olfactometric uncertainty
No full textThis work discusses the implementation of a Crude Monte Carlo, algorithm applied to an olfactometric case study. In particular, the study analyses the influence of uncertainty of the odour concentration measurement, by dynamic olfactometry, on experimental measurements, which employ a sequence of olfactometric analysis i.e. the estimation of Odour Emission Capacity per unit of volume, OEC. The evaluation of these physical quantities is function of a fixed number of odour concentrations data. According to the new provisional version of EN13725, each odour concentration measurement is affected by a degree of uncertainty, which follows a lognormal probability distribution function. In order to consider the uncertainty associated to each single odour concentration, a Crude Monte Carlo simulation has been carried out, obtaining 106 iterations of odour concentration datasets. The obtained data have been statistically analysed, highlighting that OEC follows a lognormal distribution function as well
Experimental study about the influence of wind velocity and temperature on the emission rate of vocs from liquid surface
No full textThe characterization of passive liquid area sources for the study of Volatile Organic Compounds (VOCs) emission is a matter of great concern. The volatilization of these compounds is a complex phenomenon, being potentially affected by different chemical and physical parameters. In view of this, the present study aims to investigate the influence of wind velocity and temperature on the emission of VOCs from liquid surfaces. For the purpose of this study, the behaviour of acetone and butanol in solution with water are examined by varying some parameters inside a wind tunnel system. In particular, the wind velocity flowing through the device is varied in a range from 0.02 m/s to about 0.06 m/s and the temperature of the liquid source in a range from 20 °C to 35 °C. The obtained results show as the emission rate of these two compounds appears not to be significantly affect by the wind velocity. In view of this, the approach commonly suggested to take into account a dependence of the odour emission rate on the square root of the wind velocity appears to excessively overestimate the emission rate. On the contrary, the liquid temperature highly influences the emission phenomenon leading to an increase of one order of magnitude of the emission rate. This effect is more pronounced for butanol, consistently with the
trend of several chemical-physical parameters governing the volatilization process as a function of temperature
Digital twin-based optimization and demo-scale validation of absorption columns using sodium hydroxide/water mixtures for the purification of biogas streams subject to impurity fluctuations
No full textThis paper aims to validate a demo scale plant scrubber technology through experimental campaign and development of a digital twin. Thus, it is useful to evaluate the H2S absorption process in a biogas production plant for analysis and optimization purposes. The absorber unit removes H2S through the chemical absorption via sodium hydroxide (NaOH) as wet agent (30% w/w). The column treats 300 Nm3/h of biogas, whose inlet H2S concentration ranges from 1000 to 3000 ppm. Field measurements are conducted to investigate the H2S removal efficiency. An experimental dataset is collected, processed and used as input on Aspen PLUS suite to develop the digital twin. This model is helpful to generate a large dataset and simulate operating conditions different from the demo-scale plant. The process simulation is then exploited to perform a sensitivity analysis to figure out main variables influencing the H2S removal efficiency. Operating conditions such as H2S concentration, soda concentration and flowrate, temperature, and freshwater flowrate are perturbed in the sensitivity analysis. NaOH flowrate and its concentration are the variables with the biggest impact on the process. In detail, the highest efficiency performance was obtained using 50% NaOH solution with a flowrate higher than 8 kg/h
Helicobacter pylori and Upper Endoscopy in Systemic Sclerosis: A Cross-sectional Study in the Real World
No full textBACKGROUND/AIMS: A role for Helicobacter pylori in triggering systemic sclerosis (SSc) has been proposed, but data are conflicting. In previous studies, infection has been generally searched for by using serology. We designed this study to assess H. pylori prevalence in SSc patients with histology of gastric mucosa, considered the criterion standard for infection diagnosis. METHODS: This cross-sectional study enrolled 30 SSc patients who complained of upper gastrointestinal symptoms. All underwent upper endoscopy with gastric biopsies. Endoscopic alterations were recorded, and gastric mucosa biopsies were used for both histological examination and searching for H. pylori. The role for proton-pump inhibitor (PPI) therapy was considered. Fisher exact test was used for statistical analysis. RESULTS: Data of 28 SSc patients were available, 14 with ongoing PPI therapy. Helicobacter pylori infection at histology was detected in 14.3% patients, and it equally occurred in patients with or without PPI therapy. Erosive esophagitis/Barrett esophagus was detected in 26.6% of cases. Among patients with PPI therapy, 30% received half dose only. The prevalence of intestinal metaplasia was low (14.3%). Endoscopic esophageal alterations were significantly more frequent in those patients showing anti-Scl70 antibody positivity. CONCLUSIONS: This study showed that prevalence of H. pylori is very low in SSc patients, so that it seems not having a role in triggering SSc. Management of gastroesophageal diseases in SSc patients needs to be improved, and looking to the autoimmune profile may be of help. Thus, collaboration between rheumatologist and gastroenterologist is highly recommended
A STUDY OF COSMIC RAY SECONDARIES INDUCED BY THE MIR SPACE STATION USING AMS-01
No full text(AMS-01 COLLABORATION
Osteoimmunology of Spondyloarthritis
No full textThe mechanisms underlying the development of bone damage in the context of spondyloarthritis (SpA) are not completely understood. To date, a considerable amount of evidence indicates that several developmental pathways are crucially involved in osteoimmunology. The present review explores the biological mechanisms underlying the relationship between inflammatory dysregulation, structural progression, and osteoporosis in this diverse family of conditions. We summarize the current knowledge of bone biology and balance and the foundations of bone regulation, including bone morphogenetic protein, the Wnt pathway, and Hedgehog signaling, as well as the role of cytokines in the development of bone damage in SpA. Other areas surveyed include the pathobiology of bone damage and systemic bone loss (osteoporosis) in SpA and the effects of pharmacological treatment on focal bone damage. Lastly, we present data relative to a survey of bone metabolic assessment in SpA from Italian bone specialist rheumatology centers. The results confirm that most of the attention to bone health is given to postmenopausal subjects and that the aspect of metabolic bone health may still be underrepresented. In our opinion, it may be the time for a call to action to increase the interest in and focus on the diagnosis and management of SpA
Demographic and clinical differences between ankylosing spondylitis and non-radiographic axial spondyloarthritis: results from a multicentre retrospective study in the Lazio region of Italy
No full textAxial spondyloarthritides (axSpA) are a group of disorders that share similar pathogenetic mechanisms and clinical picture. The aim of this retrospective multicentric study was to evaluate demographic and clinical differences between ankylosing spondylitis (AS) and non-radiographic axSpA (nr-axSpA) patients
Commissioning and performance of the NA62 RICH detector
No full textNA62 is the last generation kaon experiment at CERN SPS aiming to study the decay K . The goal of the experiment is to measure the decay branching ratio, (10) , with 10% precision collecting about 100 K events in three years of data taking and assuming a 10% signal acceptance. The weak signal and the huge background make the experiment very challenging. The NA62 detector must be able to reject background events from decay channels with branching ratios up to 10 orders of magnitude higher than the signal one and with similar experimental signature. In order to achieve the designed goal, good Particle Identification (PID), kinematic rejection and precise timing are required. The key element of the PID in NA62 is the Ring Imaging Cherenkov detector (RICH) to identify pions and muons and to measure the particle arrival time. After a pilot run in 2014, installation and commissioning of the detector were completed in 2015, when also the first physics run took place. Results on the detector performance will be presented together with preliminary results from the 2015 and 2016 physics runs
Mirror system of the RICH detector of the NA62 experiment
No full textA large RICH detector is used in NA62 to suppress the muon contamination in the charged pion selection by a factor 100 in the momentum range between 15 and 35 GeV/c. The detector consists of a 17 m long tank (vessel), filled with neon gas at atmospheric pressure. Cherenkov light is reflected by a mosaic of 20 spherical mirrors with 17 m focal length, placed at the downstream end, and collected by 1952 photomultipliers (PMTs) placed at the upstream end. In this paper the characterization of the mirrors before installation and the mirror support system are described. The mirror installation procedure and the laser alignment are also illustrated
Performance of the NA62 RICH detector
No full textNA62 is the last generation kaon experiment at CERN SPS aiming to study the decay K+ _ π+νν̅. The goal of the experiment is to measure the decay branching ratio (O(10-10)) with 10% accuracy, collecting about 100 K+ → π+νν̅ events in three years of data taking and assuming a 10% signal acceptance. The NA62 detector must be able to reject background events from decay channels with branching ratios up to 10 orders of magnitude higher than the signal and with similar experimental signature. To this purpose, good Particle Identification (PID) and kinematic rejection are required. Precise timing is also needed to correctly associate the π+ with the parent K+ in a high rate environment. The key element of the PID in NA62 is the Ring Imaging CHerenkov detector (RICH) to identify π and μ in the momentum range between 15 and 35 GeV/c with a muon rejection factor better than 1%; it is also required to measure the pion arrival time with a precision better than 100 ps and the Cherenkov angle with a resolution better than 80 μ rad. Finally, it must provide a fast L0 trigger signal for charged particles. At the beginning of the NA62 pilot run, from mid October to mid December 2014, the RICH detector was completely installed and ready to take data. The installation details and the results on the detector performance will be presented together with preliminary results from the first NA62 physics run in 2015
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