Optimization of desulphurization process in a flue gas obsorber by adjusting flow patterns and rotary atomizer

Paper presented at the 5th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, South Africa, 1-4 July, 2007.Efficiency of desulphurization process in a flue gas absorber depends strongly on flow patterns of the continuous gas phase and interaction with water slurry phase that is injected into the absorber. The main task is to ensure that undesulphurized flue gas moves optimally to where a high concentration of water slurry in the form of droplets “flies”. In the paper, a model for desulphurization process is presented. The problem was solved using commercial CFD code StarCD into which a model for desulphurization was integrated. The model distinguishes between two phases of heat and mass transfer. One called “constant rate period” where the water droplet formed by an aggregate of calcium hydroxide particles encapsulated in water evaporates by convection mechanism and sulphur dioxide is transferred by the same mechanism. In this phase the spherical reaction front recedes as calcium hydroxide is converted. In the second phase called “falling rate period” water is contained only in the free space between solid particles of calcium hydroxide and sulphur dioxide is transferred by diffusion that is modified by tortuosity reflecting torturous paths inside the structure of particles. By the same mechanism water evaporates from the aggregate of particles. A model for age of flue gas was developed that shows residing time of flue gas in individual parts of the absorber. Together with values of water content and void fraction of water phase one can suggest different design modifications of the absorber (for example different inclination of inlet vanes that guide the flue gas into the absorber).cs201

Transport and deposition of aerosols in human airways

Paper presented at the 5th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, South Africa, 1-4 July, 2007.A numerical model of aerosol transport in human airways is presented that contains 6 to 9 bifurcations and about 100 terminations. The model was acquired from a CT scan of a living person and contains oral/nasal cavity, thoracic and lower airways. Two breathing activities are modeled: 1) Resting conditions with a tidal volume 0,5liter, the minute ventilation 15 l/min and the period 4 sec/cycle and 2) Heavy activity (maximum exercise) with the tidal volume 3.33 liter, the minute ventilation 120 l/min and the period 1.25 sec/cycle. The inspiration/expiration cycle was modeled following the sinusoidal function. Euler-Lagrange approach was used to model aerosol transport and deposition in the airways. The total concentration of aerosol was assumed 50μg/m3 divided into three classes PM10, PM2.5 a PM 1 with appropriate fractions 25μg/m3, 9 μg/m3 and 16 μg/m3, respectively. Results of the modeling show the velocity field in several locations along the airways in different time steps of inspiration and expiration phases as well as deposition of individual aerosol sizes in the individual segments of the human airways.cs201

Assessing the volcanic hazard for Rome. 40Ar/39Ar and In-SAR constraints on the most recent eruptive activity and present-day uplift at Colli Albani Volcanic District

We present new 40Ar/39Ar data which allow us to refine the recurrence time for the most recent eruptive activity occurred at Colli Albani Volcanic District (CAVD) and constrain its geographic area. Time elapsed since the last eruption (36 kyr) overruns the recurrence time (31 kyr) in the last 100 kyr. New interferometric synthetic aperture radar data, covering the years 1993–2010, reveal ongoing inflation with maximum uplift rates (>2 mm/yr) in the area hosting the most recent (<200 ka) vents, suggesting that the observed uplift might be caused by magma injection within the youngest plumbing system. Finally, we frame the present deformation within the structural pattern of the area of Rome, characterized by 50 m of regional uplift since 200 ka and by geologic evidence for a recent (<2000 years) switch of the local stress-field, highlighting that the precursors of a new phase of volcanic activity are likely occurring at the CAVD

Examining the Effects of Formal Education Level on the Montreal Cognitive Assessment

Background: Brief, global assessments such as the Montreal Cognitive Assessment (MoCA) are widely used in primary care for assessing cognition in older adults. Like other neuropsychological instruments, lower formal education can influence MoCA interpretation. Methods: Data from 2 large studies of cognitive aging were used—Alzheimer’s Disease Neuroimaging Initiative (ADNI) and National Alzheimer’s Coordinating Center (NACC). Both use comprehensive examinations to determine cognitive status and have brain amyloid status for many participants. Mixed models were used to account for random variation due to data source. Results: Cognitively intact participants with lower education (≤12 years) were more likely than those with higher education (\u3e12 years) to be classified as potentially impaired using the MoCA cutoff of \u3c26 (P \u3c .01). Backwards selection revealed 4 MoCA items significantly associated with education (cube copy, serial subtraction, phonemic fluency, abstraction). Subtracting these items scores yielded an alternative MoCA score with a maximum of 24 and a cutoff of ≤19 for classifying participants with mild cognitive impairment. Using the alternative MoCA score and cutoff, among cognitively intact participants, both education groups were similarly likely to be classified as potentially impaired (P \u3e .67). Conclusions: The alternative MoCA score neutralized the effects of formal education. Although further research is needed, this alternative score offers a simple procedure for interpreting MoCAs administered to older adults with ≤12 years education. These educational effects also highlight that the MoCA is part of the assessment process—not a singular diagnostic test—and a comprehensive workup is necessary to accurately diagnose cognitive impairments

Liquid wall film formation in steam piping in nuclear plant

Paper presented at the 5th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, South Africa, 1-4 July, 2007.A numerical investigation is carried out for turbulent droplet-laden flow of saturated steam produced in a steam generator (SG) that feeds steam turbine (ST) through a long and multi-bend steam piping. The main purpose of the study is to analyze deposition of droplets that form a wall film in the piping system. Two tasks were performed: parametric study of the deposition in 90° elbows and the deposition in a more complex piping system. This system starts with outlets from the steam generator with five mouthpieces leading to a collector pipe and connecting the steam piping leading to a steam turbine. Results of the simulations show where droplets deposit and where a liquid separator should be placed to drain away the water film and to avoid droplets from entering the steam turbine. Dynamic temporal development of the film is presented showing mutual impact of gravity and entrainment by the co-flowing steam.cs201

Major explosive activity in the Monti Sabatini Volcanic District(central Italy) over the 800-390ka interval: Geochronological-geochemical overview and tephrostratigraphic implications

A review of the existing chronological, stratigraphic and chemo-petrologic data of the major eruptive units from the early phase of activity (800-390ka) in the Monti Sabatini Volcanic District (MSVD), belonging to the ultra-potassic magmatic region of central Italy, is presented along with new radioisotopic age determinations and geochemical analyses. Through the combined use of electron microprobe glass compositions, selected trace-element compositions, and single-crystal 40Ar/39Ar age determinations, we provide a new chrono- and chemo-stratigraphic classification of the products emplaced in the 800-390ka time interval. Besides giving insights on the petrologic evolution of the Roman Comagmatic Region, the large dataset provides fundamental information that is applicable to tephrostratigraphic studies in the wide region encompassing the Tyrrhenian Sea margin to the Adriatic Sea basin. Distal tephras from this volcanic activity also act as important geochronologic markers for the coastal sedimentary successions deposited in response to glacio-eustatic fluctuations, as well as for successions in the Quaternary tectonic basins of the Central and Southern Apennines. An innovative approach based on the use of discrimination diagrams of Zr/Y vs Nb/Y ratios for fingerprinting altered volcanic rocks - recently developed and successfully employed in archaeometric studies - is here combined to the glass compositions for classifying the MSVD deposits and tested on two distal tephra layers, showing its potentiality for tephrostratigraphic correlation. © 2014 Elsevier Ltd

Plasma Neuronal Exosomal Levels of Alzheimer\u27s Disease Biomarkers in Normal Aging

Plasma neuronal exosomal levels of pathogenic Alzheimer\u27s disease (AD) proteins, cellular survival factors, and lysosomal proteins distinguish AD patients from control subjects, but changes in these exosomal proteins associated with normal aging have not been described for cognitively intact subjects. Plasma neuronal exosomal levels of P-T181-tau, P-S396-tau, Aβ1-42, cathepsin D, repressor element 1-silencing transcription factor, and neurogranin were quantified longitudinally in cognitively intact older adults using two samples collected at 3- to 11-year intervals. Except for P-S396-tau, exosomal protein levels changed significantly with aging, but were largely outside the range observed in AD patients

Enlarged Perivascular Spaces are Negatively Associated with Montreal Cognitive Assessment Scores in Older Adults

Emerging evidence suggests that enlarged perivascular spaces (ePVS) may be a clinically significant neuroimaging marker of global cognitive function related to cerebral small vessel disease (cSVD). We tested this possibility by assessing the relationship between ePVS and both a standardized measure of global cognitive function, the Montreal Cognitive Assessment (MoCA), and an established marker of cSVD, white matter hyperintensity volume (WMH) volume. One hundred and eleven community-dwelling older adults (56–86) underwent neuroimaging and MoCA testing. Quantification of region-specific ePVS burden was performed using a previously validated visual rating method and WMH volumes were computed using the standard ADNI pipeline. Separate linear regression models were run with ePVS as a predictor of MoCA scores and whole brain WMH volume. Results indicated a negative association between MoCA scores and both total ePVS counts (P ≤ 0.001) and centrum semiovale ePVS counts (P ≤ 0.001), after controlling for other relevant cSVD variables. Further, WMH volumes were positively associated with total ePVS (P = 0.010), basal ganglia ePVS (P ≤ 0.001), and centrum semiovale ePVS (P = 0.027). Our results suggest that ePVS burden, particularly in the centrum semiovale, may be a clinically significant neuroimaging marker of global cognitive dysfunction related to cSVD

Water Exchange Rate across the Blood-Brain Barrier Is Associated with CSF Amyloid-β 42 in Healthy Older Adults

INTRODUCTION: We tested if water exchange across the blood-brain barrier (BBB), estimated with a noninvasive magnetic resonance imaging (MRI) technique, is associated with cerebrospinal fluid (CSF) biomarkers of Alzheimer\u27s disease (AD) and neuropsychological function. METHODS: Forty cognitively normal older adults (67–86 years old) were scanned with diffusion‐prepared, arterial spin labeling (DP‐ASL), which estimates water exchange rate across the BBB (kw). Participants also underwent CSF draw and neuropsychological testing. Multiple linear regression models were run with kw as a predictor of CSF concentrations and neuropsychological scores. RESULTS: In multiple brain regions, BBB kw was positively associated with CSF amyloid beta (Aβ)42 concentration levels. BBB kw was only moderately associated with neuropsychological performance. DISCUSSION: Our results suggest that low water exchange rate across the BBB is associated with low CSF Aβ42 concentration. These findings suggest that kw may be a promising noninvasive indicator of BBB Aβ clearance functions, a possibility which should be further tested in future research

Self-Reported Sleep Apnea and Dementia Risk: Findings from the Prevention of Alzheimer\u27s Disease with Vitamin E and Selenium Trial

OBJECTIVES: To investigate the association between baseline sleep apnea and risk of incident dementia in the Prevention of Alzheimer\u27s Disease with Vitamin E and Selenium (PREADViSE) study and to explore whether the association depends on apolipoprotein E (APOE) ɛ4 allele status. DESIGN: Secondary analysis based on data collected during PREADViSE. SETTING: Participants were assessed at 128 local clinical study sites during the clinical trial phase and later were followed by telephone from a centralized location. PARTICIPANTS: Men enrolled in PREADViSE (without dementia or other active neurological conditions that affect cognition such as major psychiatric disorders, including depression; N = 7,547). MEASUREMENTS: Participants were interviewed at baseline for sleep apnea. The Memory Impairment Screen (MIS) was administered to each participant annually. Subjects who failed this initial screen were tested with secondary screening tests. Medical history and medication use were determined, and the AD8 dementia screening instrument was used. RESULTS: The effect of self-reported sleep apnea on dementia risk depended on APOE ɛ4 status. When the allele was absent, baseline self-reported sleep apnea was associated with a 66% higher risk of developing dementia (95% confidence interval = 2-170%), whereas self-reported sleep apnea conferred no additional risk for participants with an ɛ4 allele. CONCLUSION: Sleep apnea may increase risk of dementia in the absence of APOE ɛ4. This may help inform prevention strategies for dementia or AD in older men with sleep apnea. Registration: PREADViSE is registered at ClinicalTrials.gov: NCT00040378