During the Shanghai World Expo 2010 ground based Multi-Axis Differential Optical Absorption Spectroscopy (MAX-DOAS) measurements of tropospheric nitrogen dioxide (NO2) were performed to investigate ...the effects of emission control measures during that time. In this study we measured NO2 using four identical MAX-DOAS instruments in Shanghai from April 2009 to November 2010. We combined our MAX-DOAS data, the Ozone Monitoring Instrument (OMI) satellite observations and meteorological information from the National Centers for Environmental Prediction final reanalysis data (NCEP FNL) in order to investigate the spatial distribution of NO2 over Shanghai and the effects of emission control measures during the Expo. In general, the comparison of cloud screened MAX-DOAS data and OMI observations are in good correlation (Pearson correlation coefficient between 0.67 and 0.93 for the four measurement stations). In addition, we compared the MAX-DOAS and OMI NO2 data from the Shanghai Expo in 2010 to the same time of the year in 2009. The results show that the NO2 columns were reduced up to ∼ 30% in the area of central Shanghai during the Expo but no significant reduction of NO2 levels was found in the nearby industrial area. The overall NO2 reduction from May, July and September 2010 ranged from 7.5% to 14.5%, which is comparable to observations in previous studies. Our results revealed that the NO2 reduction was mainly achieved by emission control policies on transportation sources in the city rather than the controls from nearby provinces.
•We examined the reduction of NO2 during Expo 2010.•Ground based MAX-DOAS, OMI satellite and NCEP FNL meteorological data are used.•The NO2 reduction during the Expo ranged from 7.5% to 14.5%.•The NO2 reduction was mainly achieved by reduction of transportation emissions.•The emission control measures were effective only within a relatively small area.
We report a new design of carbon nanotube (CNT) resonator, whose resonance frequency can be tuned not only transversally by a gate voltage, but also by the axial strain applied through directly ...pulling the CNT. The resonators are fabricated from individual suspended single-walled CNT (SWCNT) in situ inside a scanning electron microscope. The resonance frequency of a SWCNT resonator can be tuned by more than 20 times with an increase of quality factor when the axial strain of the SWCNT is only increased from nearly zero to 2% at room temperature. The transversal gate-tuning ability is found to be weaker than the axial-tuning ability and decrease with increasing the axial strain. The gate voltage can hardly tune the resonance frequency when the initial axial strain is larger than 0.35% and the CNT acts like a tied string. The relationship among resonance frequency, gate voltage, and initial axial strain of the CNT obtained presently will allow for the designs of CNT resonators with high frequency and large tuning range. The present resonator also shows ultrahigh sensitivity in displacement and force detection, with a resolution being better than 2.4 pm and 0.55 pN, respectively.
Urban sprawl has become a huge concern for cities like Los Angeles, New York, and Chicago in recent years. As urban sprawl pushes urbanization into city suburbs and outskirts, forest fragmentation ...becomes evidently prevalent and exposes forests to high temperatures, pollution, pests, and fires that threaten forest health. A 2021 report titled Rebuilding for a Resilient Recovery affirmed that the frequency and damage potential of wildfires have been exacerbated by climate change and urban sprawl especially in California. Globally, these fires can be attributed to both natural and anthropogenic drivers such as deforestation, agriculture, mining, and industrialization. Future projections predict that these incidences of fires will only worsen as the planet continues to warm further, with emphasis on the spread and intensities of the annual California wildfires over the decade. Quantifying the consequences of these fires on global climate change has become crucial and with the emergence of advanced GIS mapping tools, focus, visualization, and interpretation of fire and burn severity has become easier. However, knowledge and understanding of wildfire dynamics is limited especially in terms of fuel load, impacts on vegetation health, aerosol release and associated movement in the atmosphere. It is therefore important to address these gaps to make better and informed actions towards forest use, protection, management, and policies and broadly towards ambitious climate goals such as the UN’s Carbon Neutral goal by 2050. This study uses Sentinel 2A data from the Copernicus fleet between 2018 and 2022 to identify and assess the burn severity of affected areas in Sonoma County, California. The aim of the study is to understand the impacts of fires of fire on vegetation health and the post-fire recovery process. The Normalized Burn Ration Index (NBRI) was used to identify and measure the extent of the burnt areas within the county and their severity and Normalized Difference Vegetation Index (NDVI) was used as a measure of forest heath. The results show that Sonoma County has become a high burn severity area with a major decrease in unburned areas between 2018 and 2022. NDVI values recorded all decrease from January to December for all the years because of pre-fire season drought. The wildfire season begins in May and before then there are seasonal droughts that occur hence accounting for the initial decline in NDVI. The least values recorded were between 0.5 and 0.57 for September, indicating sparse and unhealthy vegetation because of sharp declines during the fire season.
The use of air sensor technology is increasing worldwide for a variety of applications, however, with significant variability in data quality. The United States Environmental Protection Agency held a ...workshop in July 2019 to deliberate possible performance targets for air sensors measuring particles with aerodynamic diameters of 10 μm or less (PM10), nitrogen dioxide (NO2), carbon monoxide (CO), and sulfur dioxide (SO2). These performance targets were discussed from the perspective of non-regulatory applications and with the sensors operating primarily in a stationary mode in outdoor environments. Attendees included representatives from multiple levels of government organizations, sensor developers, environmental nonprofits, international organizations, and academia. The workshop addressed the current lack of sensor technology requirements, discussed fit-for-purpose data quality needs, and debated transparency issues. This paper highlights the purpose and key outcomes of the workshop. While more information on performance and applications of sensors is available than in past years, the performance metrics, or parameters used to describe data quality, vary among the studies reports and there is a need for more clear and consistent approaches for evaluating sensor performance. Organizations worldwide are increasingly considering, or are in the process of developing, sensor performance targets and testing protocols. Workshop participants suggested that these new guidelines are highly desirable, would help improve data quality, and would give users more confidence in their data. Given the wide variety of uses for sensors and user backgrounds, as well as varied sensor design features (e.g., communication approaches, data tools, processing/adjustment algorithms and calibration procedures), the need for transparency was a key workshop theme. Suggestions for increasing transparency included documenting and sharing testing and performance data, detailing best practices, and sharing data processing and correction approaches.
•Performance targets would assist in selecting sensors appropriate for a given use.•Varying sensor performance metrics are currently reported in literature.•Transparency and consistency in performance metrics is recommended.•Documenting sensor calibration and processing algorithms is recommended.
The Keta Municipality has undergone a rapid increase in population due to economic and commercial activities. This led to the municipal’s coastal and shoreline zone being faced with severe ...environmental challenges throughout the years. The goal of the study was to evaluate Keta’s shoreline changes and the coastal Land Use Land Cover (LULC) using multi-temporal remote sensing datasets. These datasets were subjected to the following image processing techniques such as image enhancement, image classification and, shoreline extraction. The Digital Shoreline Analysis System (DSAS), a plugin tool in ArcGIS was utilized to assess the rate of shoreline changes (i.e., erosion or accretion) from 2000 to 2020. These were achieved based on the following statistical methods used; Linear Regression Rate (LRR), Net Shoreline Movement (NSM), and End Point Rate (EPR). The LULC analysis indicated that built-up areas and water bodies have increased rapidly from 14.71–18.43%, and 47.68–50.46% respectively from 2000 to 2021. In terms of the shoreline changes, LRR showed a mean of −0.95m/year with 68.22% faced with erosion and accretion of 31.78%. The EPR and NSM revealed a mean shoreline change of −1.19m/year and −26.3/period respectively from 2000 to 2021. The EPR and NSM results both revealed that 69.24% experienced erosion and 30.76% accretion, indicating the prevalence of erosion at the shoreline. This research is to contribute to both the development of Keta’s shoreline protection and management measures as well as sustainable land use planning. Also, aids in achieving most of the Sustainable Development Goals in the municipal.
To explore the clinical features of fatty liver disease (FLD) from non-alcoholic fatty liver disease (NAFLD) to metabolic dysfunction-associated fatty liver disease (MASLD), so as to elucidate its ...clinical application value under three renames.
Patients who were hospitalized in the Department of Hepatology, Hospital of Traditional Chinese Medicine Affiliated to Xinjiang Medical University, from January 2020 to September 2023 and met the diagnosis of NAFLD, metabolic-associated fatty liver disease (MAFLD), or MASLD were selected as the research subjects. The clinical indicators differences among the three groups of patients were compared, mainly including general information (age, gender, body mass index, past history, etc.), serological indicators (liver and kidney function, blood lipids, blood sugar, coagulation function, etc.), non-invasive liver fibrosis indicators, fat attenuation parameters, etc. Measurement data were analyzed using ANOVA and the rank sum test, while count data were analyzed using the
(2
We study the exciton polariton contribution to the Stokes shift in colloidal quantum dots (QDs). By detailed quantum mechanical description of light−matter interaction and temporal analysis of ...incident electromagnetic field across the QD using the finite-difference time-domain method, we have shown that the optical excitation of an exciton in the QD and its coupling with the excitation radiation (i.e., exciton polariton) induce strong variations in the dielectric constant of the QD which contribute significantly to the Stokes shift and cause modifications in the absorption spectrum that agrees well with experiments.
Urban ecosystems face numerous challenges due to rapid urbanization and population growth. Effective management of these ecosystems is crucial to ensure their sustainability and the well-being of ...urban residents. Remote sensing (RS) and Geographic Information Systems (GIS) have emerged as valuable tools for understanding and managing urban ecosystems. The integration of remote sensing and GIS technologies facilitate the monitoring and assessment of urban biodiversity, aiding in the conservation and restoration of ecological habitats. With this mind, the objective of this study was to investigate the integration of remote sensing and GIS technologies for real-time monitoring and assessment of environmental parameters in urban ecosystems, and their role in supporting sustainable urban ecosystem conservation efforts. Landsat 8 Operational Land Imager (OLI) images were acquired between January 2nd and April 5th 2020 to assess and monitor the dynamics in urban ecosystems in Abidjan, Accra, and Lagos. The Normalized Difference Built-up index was used to detect areas covered with concrete structures and impervious surfaces, while the Normalized Difference Vegetation Index and Normalized Difference Water Index were used to detect areas covered with vegetation and water bodies, respectively. Results of the study show that Abidjan, Accra, and Lagos experienced increased built-up areas at the expense of other land uses such as forests. Remote Sensing and GIS technologies provide valuable insights into the spatial and temporal dynamics of urban environments, supporting evidence-based decision-making and sustainable urban planning and development.
PDF
