85 research outputs found
Effect of short–time variations of wind velocity on mass transfer rate between street canyons and the atmospheric boundary layer
Abstract 2D URANS CFD simulations were conducted to study the effect of short–time variations of wind velocity on mass transfer rate between street canyons and the atmospheric boundary layer (ABL). A street canyon with a height–to– width ratio (aspect ratio) of three was considered as a case study. The study is of practical interest since it illustrates a skimming flow regime, the regime where pollutants are less effectively exchanged between the canyon and the above atmosphere, typically found in many urban areas in Mediterranean countries. Short–time variations of wind velocity magnitude were simulated assuming a sinusoidal function with average magnitude = 4 m s −1 ; amplitude ±2 m s −1 and period from 1 to 40 s, and subsequently with short–time averaged (0.1 s, 1 s and 10 s) real world data measured with an ultrasonic anemometer (50 Hz). Mass transfer rate between the canyon and the ABL was evaluated as the rate of reduction of spatially averaged concentration of a passive pollutant, carbon monoxide (CO), in the street canyon. Results show that mass transfer rate increases with the frequency of short–time variations. In CFD studies pertaining to pollutant dispersion in street canyons, wind hourly average velocity is usually assumed as a reference value to simulate real world cases. Our results show that this input data must be completed with additional information about the extent of variation in wind intensity and its frequency in the hour
Surgical treatment of an aseptic fistulized acromioclavicular joint cyst: a case report and review of the literature
An acromioclavicular joint cyst is an uncommonly reported condition, which seems to result from a massive rotator cuff tear and degenerative osteoarthritis of the acromioclavicular joint. We present the case of an 81-year-old man affected by an acromioclavicular joint cyst, associated to a massive rotator cuff tear, proximal migration of the humeral head and osteoarthritis of the gleno-humeral joint. The mass was 7 × 2.5 cm in size and the overlying skin presented a fistula that drained clear synovial-like fluid. Plain X-ray examination of the left shoulder showed proximal migration of the humeral head migration and osteoarthritis of the gleno-humeral joint, and further MRI evaluation confirmed the clinical diagnosis of a complete rotator cuff tear and observed a large subcutaneous cyst in communication with the degenerative acromioclavicular joint. The patient underwent surgical excision of the cyst and lateral resection of the clavicle to prevent disease recurrence. To the best of our knowledge, this is the first reported case of an acromioclavicular joint cyst complicated by an aseptic fistula resulting from multiple aspirations
Surgical treatment of an aseptic fistulized acromioclavicular joint cyst: a case report and review of the literature.
An acromioclavicular joint cyst is an uncommonly reported condition, which seems to result from a massive rotator cuff tear and degenerative osteoarthritis of the acromioclavicular joint. We present the case of an 81-year-old man affected by an acromioclavicular joint cyst, associated to a massive rotator cuff tear, proximal migration of the humeral head and osteoarthritis of the gleno-humeral joint. The mass was 7 x 2.5 cm in size and the overlying skin presented a fistula that drained clear synovial-like fluid. Plain X-ray examination of the left shoulder showed proximal migration of the humeral head migration and osteoarthritis of the gleno-humeral joint, and further MRI evaluation confirmed the clinical diagnosis of a complete rotator cuff tear and observed a large subcutaneous cyst in communication with the degenerative acromioclavicular joint. The patient underwent surgical excision of the cyst and lateral resection of the clavicle to prevent disease recurrence. To the best of our knowledge, this is the first reported case of an acromioclavicular joint cyst complicated by an aseptic fistula resulting from multiple aspirations
Assessment of ambient air quality in the port of Naples
Two experimental monitoring campaigns were carried out in 2012 to investigate the air quality in the port of Naples, the most
important in southern Italy for traffic of passengers and one of the most important for goods. Therefore, it represents an
important air pollution source located close to the city of Naples. The concentrations of sulfur dioxide (SO2), nitrogen dioxide
(NO2), and BTEX (benzene, toluene, ethylbenzene, and xylenes) in the air were measured at 15 points inside the Naples port area
through the use of passive samplers. In addition, a mobile laboratory was positioned in a fixed point inside the port area to
measure continuous concentration of pollutants together with particulate matter, ambient parameters, and wind direction and
intensity. The pollution levels monitored were compared with those observed in the urban area of Naples and in other
Mediterranean ports. Even though the observation time was limited, measured concentrations were also compared with limit
values established by European legislation. All the measured pollutants were below the limits with the exception of nitrogen
dioxide: its average concentration during the exposition time exceeded the yearly limit value. A spatial analysis of data,
according to the measured wind direction and intensity, provided information about the effects that ship emissions have on
ambient air quality in the port area. The main evidence indicates that ship emissions influence sulfur dioxide concentration more
than any other pollutants analyze
Methanation of syngas from biomass gasification: Small-scale plant design in Aspen Plus
The objective of this study is to investigate the upgrading of low-quality nitrogen-diluted syngas derived from
biomass air gasification processes into a methane-rich gas stream. Both the thermodynamic and the kinetic aspects are addressed in the paper. Using the Aspen Plus software, a thermodynamic analysis was conducted; then,
different plant designs are simulated and compared, including reactor sizing and performance. The results
demonstrate that the upgrading of diluted syngas poses challenges which limit its application to small-scale
decentralized systems. It was found that a system comprising of four adiabatic fixed-bed reactors, intercooling, and efficient water removal achieves a favorable balance between performance and cost. Operating
the system at a pressure of 5 bar is deemed adequate as it reduces the required catalyst mass and prevents solid
carbon deposition. Notably, this configuration achieved good results, including a 99.4 % CO conversion, 89.3 %
CO2 conversion, and 95.6 % CH4 yield. The final methane molar content reached 26.4 %, with a calorific value of
8.62 MJ/Nm3
(STP)
Development of a Methodology for the Identification of High Emitting Mobile Sources in Narrow and Deep Street Canyons
In urban areas transport represents a significant source of atmospheric pollutants and greenhouse gases (GHG). In the case of vehicular transport, a significant contribution to total emissions is given by a category of vehicles with excessively high emissions of one or more pollutants defined as high emitting vehicles (high-emitters). High emitters can contribute a disproportionally way to total emissions of many airborne pollutants (NOx, COV, PM and GHGs). Remote sensing (RS) techniques have been developed with the aim to identify high emitterss but until now they have found only few practical applications. Among RS technologies, point sampling (PS) is the most promising for implementation in narrow and deep street canyons due to the limited impact on both pedestrians and architecture and the small space occupancy. In this paper we present results of preliminary monitoring campaigns carried out in a narrow and deep street canyon in Naples (Italy) in low-traffic conditions. Fine particles (FPs) concentration (20-1000 nm) were monitored using a condensation particle counter (CPC). Time patterns of FPs concentration have been analyzed by a code developed in MATLAB to identify FP concentration peaks and successively to attribute each identified peak to a specific vehicle. To study the effect of operating conditions (wind speed and direction) on the plume formed by vehicle exhausts, CFD simulations have been also carried out. Results show good performances of the code in the identification of FPs peaks and a limited effect of ambient parameters on the dispersion of the plumes inside the street canyon studied
Modelling of Deep Street Canyon Air Pollution Chemistry and Transport:A Wintertime Naples Case Study
Two stage fracture of a polyethylene post in a 9-year-old posterior-stabilized knee prosthesis: a case report
<p>Abstract</p> <p>Introduction</p> <p>Several cases of tibial post breakage are reported in the literature. To the best of our knowledge, only three cases of NexGen knee prosthesis (Zimmer, Warsaw, Indiana, USA) tibial post failure have been reported.</p> <p>Case presentation</p> <p>In November 1999, a 63-year-old Caucasian woman from Italy with a history of symptomatic left knee osteoarthritis underwent a total knee arthroplasty. In March 2008, while rising from a chair, she felt a sudden pain and instability in her left knee. She reported a fracture of the polyethylene post of the tibial insert. No malposition or malalignment of either the femoral or tibial components were identified. The polyethylene tibial insert was studied under light microscopy and scanning electron microscopy. The fracture was also noted to have occurred without any notable polyethylene wear.</p> <p>Conclusion</p> <p>Scanning electron microscopy revealed two different damage patterns that could be explained with a two-stage rupture of our patient's polyethylene post. This could have been caused by a non-optimal ligamentous balancing during first implant surgery. Her knee probably developed a varus instability that weakened the post, and then a posterior anterior stress finally broke the polyethylene.</p
A global observational analysis to understand changes in air quality during exceptionally low anthropogenic emission
This global study, which has been coordinated by the World Meteorological Organization Global Atmospheric Watch (WMO/GAW) programme, aims to understand the behaviour of key air pollutant species during the COVID-19 pandemic period of exceptionally low emissions across the globe. We investigated the effects of the differences in both emissions and regional and local meteorology in 2020 compared with the period 2015–2019. By adopting a globally consistent approach, this comprehensive observational analysis focuses on changes in air quality in and around cities across the globe for the following air pollutants PM2.5, PM10, PMC (coarse fraction of PM), NO2, SO2, NOx, CO, O3 and the total gaseous oxidant (OX = NO2 + O3) during the pre-lockdown, partial lockdown, full lockdown and two relaxation periods spanning from January to September 2020. The analysis is based on in situ ground-based air quality observations at over 540 traffic, background and rural stations, from 63 cities and covering 25 countries over seven geographical regions of the world. Anomalies in the air pollutant concentrations (increases or decreases during 2020 periods compared to equivalent 2015–2019 periods) were calculated and the possible effects of meteorological conditions were analysed by computing anomalies from ERA5 reanalyses and local observations for these periods. We observed a positive correlation between the reductions in NO2 and NOx concentrations and peoples’ mobility for most cities. A correlation between PMC and mobility changes was also seen for some Asian and South American cities. A clear signal was not observed for other pollutants, suggesting that sources besides vehicular emissions also substantially contributed to the change in air quality. As a global and regional overview of the changes in ambient concentrations of key air quality species, we observed decreases of up to about 70% in mean NO2 and between 30% and 40% in mean PM2.5 concentrations over 2020 full lockdown compared to the same period in 2015–2019. However, PM2.5 exhibited complex signals, even within the same region, with increases in some Spanish cities, attributed mainly to the long-range transport of African dust and/or biomass burning (corroborated with the analysis of NO2/CO ratio). Some Chinese cities showed similar increases in PM2.5 during the lockdown periods, but in this case, it was likely due to secondary PM formation. Changes in O3 concentrations were highly heterogeneous, with no overall change or small increases (as in the case of Europe), and positive anomalies of 25% and 30% in East Asia and South America, respectively, with Colombia showing the largest positive anomaly of ~70%. The SO2 anomalies were negative for 2020 compared to 2015–2019 (between ~25 to 60%) for all regions. For CO, negative anomalies were observed for all regions with the largest decrease for South America of up to ~40%. The NO2/CO ratio indicated that specific sites (such as those in Spanish cities) were affected by biomass burning plumes, which outweighed the NO2 decrease due to the general reduction in mobility (ratio of ~60%). Analysis of the total oxidant (OX = NO2 + O3) showed that primary NO2 emissions at urban locations were greater than the O3 production, whereas at background sites, OX was mostly driven by the regional contributions rather than local NO2 and O3 concentrations. The present study clearly highlights the importance of meteorology and episodic contributions (e.g., from dust, domestic, agricultural biomass burning and crop fertilizing) when analysing air quality in and around cities even during large emissions reductions. There is still the need to better understand how the chemical responses of secondary pollutants to emission change under complex meteorological conditions, along with climate change and socio-economic drivers may affect future air quality. The implications for regional and global policies are also significant, as our study clearly indicates that PM2.5 concentrations would not likely meet the World Health Organization guidelines in many parts of the world, despite the drastic reductions in mobility. Consequently, revisions of air quality regulation (e.g., the Gothenburg Protocol) with more ambitious targets that are specific to the different regions of the world may well be required.Peer reviewedFinal Published versio
A global observational analysis to understand changes in air quality during exceptionally low anthropogenic emission conditions
This global study, which has been coordinated by the World Meteorological Organization Global Atmospheric
Watch (WMO/GAW) programme, aims to understand the behaviour of key air pollutant species during the
COVID-19 pandemic period of exceptionally low emissions across the globe. We investigated the effects of the
differences in both emissions and regional and local meteorology in 2020 compared with the period 2015–2019.
By adopting a globally consistent approach, this comprehensive observational analysis focuses on changes in air
quality in and around cities across the globe for the following air pollutants PM2.5, PM10, PMC (coarse fraction of
PM), NO2, SO2, NOx, CO, O3 and the total gaseous oxidant (OX = NO2 + O3) during the pre-lockdown, partial
lockdown, full lockdown and two relaxation periods spanning from January to September 2020. The analysis is
based on in situ ground-based air quality observations at over 540 traffic, background and rural stations, from 63
cities and covering 25 countries over seven geographical regions of the world. Anomalies in the air pollutant
concentrations (increases or decreases during 2020 periods compared to equivalent 2015–2019 periods) were
calculated and the possible effects of meteorological conditions were analysed by computing anomalies from
ERA5 reanalyses and local observations for these periods. We observed a positive correlation between the reductions
in NO2 and NOx concentrations and peoples’ mobility for most cities. A correlation between PMC and
mobility changes was also seen for some Asian and South American cities. A clear signal was not observed for
other pollutants, suggesting that sources besides vehicular emissions also substantially contributed to the change
in air quality.
As a global and regional overview of the changes in ambient concentrations of key air quality species, we
observed decreases of up to about 70% in mean NO2 and between 30% and 40% in mean PM2.5 concentrations
over 2020 full lockdown compared to the same period in 2015–2019. However, PM2.5 exhibited complex signals,
even within the same region, with increases in some Spanish cities, attributed mainly to the long-range transport
of African dust and/or biomass burning (corroborated with the analysis of NO2/CO ratio). Some Chinese cities
showed similar increases in PM2.5 during the lockdown periods, but in this case, it was likely due to secondary
PM formation. Changes in O3 concentrations were highly heterogeneous, with no overall change or small increases
(as in the case of Europe), and positive anomalies of 25% and 30% in East Asia and South America,
respectively, with Colombia showing the largest positive anomaly of ~70%. The SO2 anomalies were negative for
2020 compared to 2015–2019 (between ~25 to 60%) for all regions. For CO, negative anomalies were observed for all regions with the largest decrease for South America of up to ~40%. The NO2/CO ratio indicated that
specific sites (such as those in Spanish cities) were affected by biomass burning plumes, which outweighed the
NO2 decrease due to the general reduction in mobility (ratio of ~60%). Analysis of the total oxidant (OX = NO2
+ O3) showed that primary NO2 emissions at urban locations were greater than the O3 production, whereas at
background sites, OX was mostly driven by the regional contributions rather than local NO2 and O3 concentrations.
The present study clearly highlights the importance of meteorology and episodic contributions (e.g.,
from dust, domestic, agricultural biomass burning and crop fertilizing) when analysing air quality in and around
cities even during large emissions reductions. There is still the need to better understand how the chemical
responses of secondary pollutants to emission change under complex meteorological conditions, along with
climate change and socio-economic drivers may affect future air quality. The implications for regional and global
policies are also significant, as our study clearly indicates that PM2.5 concentrations would not likely meet the
World Health Organization guidelines in many parts of the world, despite the drastic reductions in mobility.
Consequently, revisions of air quality regulation (e.g., the Gothenburg Protocol) with more ambitious targets that
are specific to the different regions of the world may well be required.World Meteorological Organization Global Atmospheric Watch
programme is gratefully acknowledged for initiating and coordinating
this study and for supporting this publication.
We acknowledge the following projects for supporting the analysis
contained in this article:
Air Pollution and Human Health for an Indian Megacity project
PROMOTE funded by UK NERC and the Indian MOES, Grant reference
number NE/P016391/1;
Regarding project funding from the European Commission, the sole
responsibility of this publication lies with the authors. The European
Commission is not responsible for any use that may be made of the information
contained therein.
This project has received funding from the European Commission’s
Horizon 2020 research and innovation program under grant agreement
No 874990 (EMERGE project).
European Regional Development Fund (project MOBTT42) under the
Mobilitas Pluss programme;
Estonian Research Council (project PRG714);
Estonian Research Infrastructures Roadmap project Estonian Environmental
Observatory (KKOBS, project 2014-2020.4.01.20-0281).
European network for observing our changing planet project (ERAPLANET,
grant agreement no. 689443) under the European Union’s
Horizon 2020 research and innovation program, Estonian Ministry of
Sciences projects (grant nos. P180021, P180274), and the Estonian
Research Infrastructures Roadmap project Estonian Environmental Observatory
(3.2.0304.11-0395).
Eastern Mediterranean and Middle East—Climate and Atmosphere Research (EMME-CARE) project, which has received funding from the
European Union’s Horizon 2020 Research and Innovation Programme
(grant agreement no. 856612) and the Government of Cyprus.
INAR acknowledges support by the Russian government (grant
number 14.W03.31.0002), the Ministry of Science and Higher Education
of the Russian Federation (agreement 14.W0331.0006), and the Russian
Ministry of Education and Science (14.W03.31.0008). We are grateful to to the following agencies for providing access to
data used in our analysis:
A.M. Obukhov Institute of Atmospheric Physics Russian Academy of
Sciences;
Agenzia Regionale per la Protezione dell’Ambiente della Campania
(ARPAC);
Air Quality and Climate Change, Parks and Environment (MetroVancouver,
Government of British Columbia);
Air Quality Monitoring & Reporting, Nova Scotia Environment
(Government of Nova Scotia);
Air Quality Monitoring Network (SIMAT) and Emission Inventory,
Mexico City Environment Secretariat (SEDEMA);
Airparif (owner & provider of the Paris air pollution data);
ARPA Lazio, Italy;
ARPA Lombardia, Italy;
Association Agr´e´ee de Surveillance de la Qualit´e de l’Air en ˆIle-de-
France AIRPARIF / Atmo-France;
Bavarian Environment Agency, Germany;
Berlin Senatsverwaltung für Umwelt, Verkehr und Klimaschutz,
Germany;
California Air Resources Board;
Central Pollution Control Board (CPCB), India;
CETESB: Companhia Ambiental do Estado de SËœao Paulo, Brazil.
China National Environmental Monitoring Centre;
Chandigarh Pollution Control Committee (CPCC), India.
DCMR Rijnmond Environmental Service, the Netherlands.
Department of Labour Inspection, Cyprus;
Department of Natural Resources Management and Environmental
Protection of Moscow.
Environment and Climate Change Canada;
Environmental Monitoring and Science Division Alberta Environment
and Parks (Government of Alberta);
Environmental Protection Authority Victoria (Melbourne, Victoria,
Australia);
Estonian Environmental Research Centre (EERC);
Estonian University of Life Sciences, SMEAR Estonia;
European Regional Development Fund (project MOBTT42) under
the Mobilitas Pluss programme;
Finnish Meteorological Institute;
Helsinki Region Environmental Services Authority;
Haryana Pollution Control Board (HSPCB), IndiaLondon Air Quality
Network (LAQN) and the Automatic Urban and Rural Network (AURN)
supported by the Department of Environment, Food and Rural Affairs,
UK Government;
Madrid Municipality;
Met Office Integrated Data Archive System (MIDAS);
Meteorological Service of Canada;
Minist`ere de l’Environnement et de la Lutte contre les changements
climatiques (Gouvernement du Qu´ebec);
Ministry of Environment and Energy, Greece;
Ministry of the Environment (Chile) and National Weather Service
(DMC);
Moscow State Budgetary Environmental Institution
MOSECOMONITORING.
Municipal Department of the Environment SMAC, Brazil;
Municipality of Madrid public open data service;
National institute of environmental research, Korea;
National Meteorology and Hydrology Service (SENAMHI), Peru;
New York State Department of Environmental Conservation;
NSW Department of Planning, Industry and Environment;
Ontario Ministry of the Environment, Conservation and Parks,
Canada;
Public Health Service of Amsterdam (GGD), the Netherlands.
Punjab Pollution Control Board (PPCB), India.
R´eseau de surveillance de la qualit´e de l’air (RSQA) (Montr´eal);
Rosgydromet. Mosecomonitoring, Institute of Atmospheric Physics,
Russia;
Russian Foundation for Basic Research (project 20–05–00254)
SAFAR-IITM-MoES, India;
SËœao Paulo State Environmental Protection Agency, CETESB;
Secretaria de Ambiente, DMQ, Ecuador;
SecretarÃa Distrital de Ambiente, Bogot´a, Colombia.
Secretaria Municipal de Meio Ambiente Rio de Janeiro;
Mexico City Atmospheric Monitoring System (SIMAT); Mexico City
Secretariat of Environment, SecretarÃa del Medio Ambiente (SEDEMA);
SLB-analys, Sweden;
SMEAR Estonia station and Estonian University of Life Sciences
(EULS);
SMEAR stations data and Finnish Center of Excellence;
South African Weather Service and Department of Environment,
Forestry and Fisheries through SAAQIS;
Spanish Ministry for the Ecological Transition and the Demographic
Challenge (MITECO);
University of Helsinki, Finland;
University of Tartu, Tahkuse air monitoring station;
Weather Station of the Institute of Astronomy, Geophysics and Atmospheric
Science of the University of SËœao Paulo;
West Bengal Pollution Control Board (WBPCB).http://www.elsevier.com/locate/envintam2023Geography, Geoinformatics and Meteorolog
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