147 research outputs found
Determination of radionuclides in Mytilus galloprovicialis by Alpha And Gamma-Spectroscopy
The natural radionuclides 238U ,234Th, 40K and the main man-made 137Cs, have been studied in Mytilus galloprovincialis (Lamarck, 1819) sampled in the Thermaikos gulf – North Aegean Sea, considered as a bioindicator for radiological assessment in the Mediterranean. The ratio 234U/238U has also been determined. In terms of 137Cs, the activity concentrations in seawater from the studied area have been measured as well, and the concentration factors of 137Cs in Mytilus galloprovincialis are given as a parameter of the organism response to radioactive pollution
Use of 137 Cs isotopic technique in soil erosion studies in Central Greece
The 137Cs technique was used to study soil erosion and deposition rates in soils in the Viotia prefecture, central Greece. Three sites with different soil types were selected and studied. Soils were sampled along transects and analyzed for 137Cs. The main goal of this field investigation was to study the 137Cs 3-D distribution pattern within key sites and to apply this information for the assessment of soil redistribution. The erosion and deposition rates were estimated using the proportional and the simplified mass balance models (Walling and He, 1997). Erosion and deposition rates predicted through the spatial distribution of 137Cs depended on the location of the profile studied in the landscape and were determined by the soil plough depth, the soil structure (bulk density), and the calibration model used to conve rt soil 137Cs measurements to estimates of soil redistribution rates. Estimated erosion rates for the Mouriki area site, varied from 16.62 to 102.56 t ha-1 y-1 for the top of the slope soil profile and from 5.37 to 25.68 t ha-1 y-1 for the middle of the slope soil profile. The deposition rates varied from 7.26 to 42.95 t ha-1 y-1 for the bottom of the slope soil profile
Use of 137 Cs isotopic technique in soil erosion studies in Central Greece
The 137Cs technique was used to study soil erosion and deposition rates in soils in the Viotia prefecture, central Greece. Three sites with different soil types were selected and studied. Soils were sampled along transects and analyzed for 137Cs. The main goal of this field investigation was to study the 137Cs 3-D distribution pattern within key sites and to apply this information for the assessment of soil redistribution. The erosion and deposition rates were estimated using the proportional and the simplified mass balance models (Walling and He, 1997). Erosion and deposition rates predicted through the spatial distribution of 137Cs depended on the location of the profile studied in the landscape and were determined by the soil plough depth, the soil structure (bulk density), and the calibration model used to conve rt soil 137Cs measurements to estimates of soil redistribution rates. Estimated erosion rates for the Mouriki area site, varied from 16.62 to 102.56 t ha-1 y-1 for the top of the slope soil profile and from 5.37 to 25.68 t ha-1 y-1 for the middle of the slope soil profile. The deposition rates varied from 7.26 to 42.95 t ha-1 y-1 for the bottom of the slope soil profile
Oxidative Potential of Atmospheric Particles at an Eastern Mediterranean Site
Aerosol oxidative potential (OP; the inherent ability of
ambient particles to generate reactive oxygen species in
vivo) may be linked to the health effects of population
exposure to aerosol and is a metric of their toxicity. The
goal of this work was to quantify the water-soluble OP of
particles in an urban area in Patras, Greece and to
investigate its links with source emissions or components
of this particulate matter (PM).
A field campaign was conducted during a monthlong
wintertime period in 2020 (January 10 to February
13) on the campus of the University of Peloponnese in
the southwest of Patras. During this time, ambient filter
samples (a total of 35 filters) were collected.
To measure the water-soluble OP we used a semiautomated
system similar to Fang et al. (2015) based on
the dithiothreitol (DTT) assay. The accuracy of our system
was validated by measuring the DTT activity of 11
phenanthrequinone (PQN) solutions on both our system
and the identical semi-automated validated system at
the National Observatory of Athens (NOA). These two
sets of analysed DTT activities (current vs. NOA system)
were significantly correlated (R2=0.99) with a slope of
1.15 ± 0.04 and an intercept close to zero.
We found that the average water-soluble OP in
Patras was 1.5 ± 0.3 nmol min-1 m-3, ranging from 0.7 to
2 nmol min-1 m-3. The OP measured in Patras during the
campaign is higher than reported values from similar
wintertime studies in other urban areas such as Athens
(Paraskevopoulou et al., 2019). The average watersoluble
OP during a summer study for Patras was
significantly lower and equal to 0.18 ± 0.02 nmol min-1 m-
3. Taking into account the average PM1 mass
concentrations for these two periods (summer: 6 μg m-3
and winter: 23 μg m-3) it is clear that the increase in OP
was two times the increase in PM mass making the
wintertime aerosol more toxic.
Additionally, the water-soluble brown carbon
(BrC) was determined using an offline semi-automated
system, where absorption was measured over a 1 m path
length. The average BrC absorption in Patras at a
wavelength of 365 nm was 8.6 ± 3.9 Mm-1 suggesting that
there was significant BrC in the organic aerosol during
this period.
The coefficients of determination, R2, in Table 1
are used as a metric of the potential relationships
between the various carbonaceous aerosol components
and the DTT activity. The results suggest that the OP is
not dominated by a single source or component, but that
there are multiple components contributing to it during
the study period.
Interestingly, the highest correlation coefficient
(R2 = 0.46) was found between the OP and Brown Carbon.
This is consistent with recently published results for an
urban site in Atlanta where the oxidative potential
measured with the DTT method also had stronger
correlations with BrC during the winter (Gao et al., 2020)
Epidemiology, practice of ventilation and outcome for patients at increased risk of postoperative pulmonary complications
BACKGROUND Limited information exists about the epidemiology and outcome of surgical patients at increased risk of postoperative pulmonary complications (PPCs), and how intraoperative ventilation was managed in these patients.
OBJECTIVES To determine the incidence of surgical patients at increased risk of PPCs, and to compare the intraoperative ventilation management and postoperative outcomes with patients at low risk of PPCs.
DESIGN This was a prospective international 1-week observational study using the ‘Assess Respiratory Risk in Surgical Patients in Catalonia risk score’ (ARISCAT score) for PPC for risk stratification.
PATIENTS AND SETTING Adult patients requiring intraoperative ventilation during general anaesthesia for surgery in 146 hospitals across 29 countries.
MAIN OUTCOME MEASURES The primary outcome was the incidence of patients at increased risk of PPCs based on the ARISCAT score. Secondary outcomes included intraoperative ventilatory management and clinical outcomes.
RESULTS A total of 9864 patients fulfilled the inclusion criteria. The incidence of patients at increased risk was 28.4%. The most frequently chosen tidal volume (VT) size was 500 ml, or 7 to 9 ml kg1 predicted body weight, slightly lower in patients at increased risk of PPCs. Levels of positive end-expiratory pressure (PEEP) were slightly higher in patients at increased risk of PPCs, with 14.3% receiving more than 5 cmH2O PEEP compared with 7.6% in patients at low risk of PPCs (P < 0.001). Patients with a predicted preoperative increased risk of PPCs developed PPCs more frequently: 19 versus 7%, relative risk (RR) 3.16 (95% confidence interval 2.76 to 3.61), P < 0.001) and had longer hospital stays. The only ventilatory factor associated with the occurrence of PPCs was the peak pressure.
CONCLUSION The incidence of patients with a predicted increased risk of PPCs is high. A large proportion of patients receive high VT and low PEEP levels. PPCs occur frequently in patients at increased risk, with worse clinical outcome
Epidemiology, practice of ventilation and outcome for patients at increased risk of postoperative pulmonary complications: LAS VEGAS - An observational study in 29 countries
BACKGROUND Limited information exists about the epidemiology and outcome of surgical patients at increased risk of postoperative pulmonary complications (PPCs), and how intraoperative ventilation was managed in these patients. OBJECTIVES To determine the incidence of surgical patients at increased risk of PPCs, and to compare the intraoperative ventilation management and postoperative outcomes with patients at low risk of PPCs. DESIGN This was a prospective international 1-week observational study using the ‘Assess Respiratory Risk in Surgical Patients in Catalonia risk score’ (ARISCAT score) for PPC for risk stratification. PATIENTS AND SETTING Adult patients requiring intraoperative ventilation during general anaesthesia for surgery in 146 hospitals across 29 countries. MAIN OUTCOME MEASURES The primary outcome was the incidence of patients at increased risk of PPCs based on the ARISCAT score. Secondary outcomes included intraoperative ventilatory management and clinical outcomes. RESULTS A total of 9864 patients fulfilled the inclusion criteria. The incidence of patients at increased risk was 28.4%. The most frequently chosen tidal volume (V T) size was 500 ml, or 7 to 9 ml kg−1 predicted body weight, slightly lower in patients at increased risk of PPCs. Levels of positive end-expiratory pressure (PEEP) were slightly higher in patients at increased risk of PPCs, with 14.3% receiving more than 5 cmH2O PEEP compared with 7.6% in patients at low risk of PPCs (P ˂ 0.001). Patients with a predicted preoperative increased risk of PPCs developed PPCs more frequently: 19 versus 7%, relative risk (RR) 3.16 (95% confidence interval 2.76 to 3.61), P ˂ 0.001) and had longer hospital stays. The only ventilatory factor associated with the occurrence of PPCs was the peak pressure. CONCLUSION The incidence of patients with a predicted increased risk of PPCs is high. A large proportion of patients receive high V T and low PEEP levels. PPCs occur frequently in patients at increased risk, with worse clinical outcome.</p
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