Nitryl Chloride (ClNO2) mixing ratios above 1aappbv have been measured off the coast of Southeast Texas. ClNO2 formation, the result of heterogeneous N2O5 uptake on chloride-containing aerosols, has ...a significant impact on oxidant formation for the Houston area. This work reports on the modeling of ClNO2 formation and describes the sensitivity of ClNO2 formation to key parameters. Model sensitivity analyses found that: (1) Chloride availability limits the formation of nitryl chloride at ground level but not aloft; (2) When excess particulate chloride was assumed to be present at ground level through sea salt, ClNO2 concentrations increased in some locations by a factor of 13, as compared to cases where sea salt chloride was assumed to be limited; (3) Inland formation of ClNO2 seems feasible based on chloride availability and could have a large impact on total ClNO2 formed in the region; and (4) ClNO2 formation is quite sensitive to the assumed yield of ClNO2 from N2O5 uptake. These results demonstrate that there is a need for further field studies to better understand the geographic extent of ClNO2 formation and the atmospheric conditions which control partitioning of chloride into the particle phase. In addition, this work examined the role of ClNO2 in the cycling of chlorine between chloride and reactive chlorine radicals. The modeling indicated that the majority of reactive chlorine in Texas along the Gulf coast is cycled through ClNO2, demonstrating the importance of including ClNO2 into photochemical models for this region.
Here we present measurements of the size‐resolved concentration and isotopic composition of atmospheric nitrate (NO3−) collected during a cruise in coastal California. Significant differences in air ...mass origin and atmospheric chemistry were observed in the two main regions of this cruise (South and Central Coast) with corresponding differences in NO3− concentration and isotope ratios. Measurements of the 17O‐excess (Δ17O) of NO3− suggest that nocturnal chemistry played an important role in terms of total NO3− production (~ 50%) in the coastal Los Angeles region (South Coast), where NO3− concentrations were elevated due to the influence of sea breeze / land breeze recirculation and Δ17O(NO3−) averaged (25.3 ± 1.6)‰. Conversely, Δ17O(NO3−) averaged (22.3 ± 1.8)‰ in the Central Coast region, suggesting that the daytime OH + NO2 reaction was responsible for 60–85% of NO3− production in the marine air sampled in this area. A strong diurnal signal was observed for both the Δ17O and δ15N of NO3−. In the case of Δ17O, this trend is interpreted quantitatively in terms of the relative proportions of daytime and nighttime production and the atmospheric lifetime of NO3−. For δ15N, which had an average value of (0.0 ± 3.2)‰, the observed diurnality suggests a combined effect of isotopic exchange between gas‐phase precursors and variability in reactive nitrogen sources. These findings represent a significant advance in our understanding of the isotope dynamics of nitrate and its precursor molecules, with potentially important implications for air quality modeling.
Key Points
Stable isotope ratios of atmospheric nitrate were measured in coastal CaliforniaOxygen isotopes are interpreted in terms of production mechanismsNitrogen isotopic composition reflects both sources and isotopic exchange
Measurements were made onboard the NOAA R/V Discoverer during the First Aerosol Characterization Experiment (ACE 1) to understand the optical properties of a minimally perturbed natural aerosol ...system in terms of its chemical and physical properties. ACE 1 took place during November and December of 1995 in the Southern Ocean region south of Australia. Reported here are observations at a wavelength of 550 nm of the submicron and supermicron aerosol scattering coefficient, σsp; single scattering albedo, ω0; and the hemispheric backscattered fraction and mass scattering efficiencies of non‐sea‐salt sulfate, sea salt, and the total aerosol. Also presented is the Ångström exponent, å, for the 450 and 700 nm wavelength pair. Variations in these parameters were found to be a strong function of the relative concentrations and size distributions of the dominant aerosol chemical components. Both the submicron and supermicron aerosol mass were composed primarily of water‐soluble ionic species. This is in agreement with an experiment‐average single scattering albedo of 0.99 (−0.4, +1.0%). Of the submicron ionic mass, 80±10% was sea salt, 16±8% was non‐sea‐salt sulfate, and 4±3% was methanesulfonate. Sea salt composed 99±0.7% of the supermicron ionic mass. The magnitude of scattering by both submicron and supermicron aerosol was controlled by sea salt. The backscattered fraction for the submicron aerosol averaged 0.11±0.02 and was controlled by the tailing of coarse mode sea‐salt mass into the submicron size range. Calculated mass scattering efficiencies for submicron non‐sea‐salt sulfate ion averaged 1.5±0.74 m2 g−1 (at 30 to 45% relative humidity) with the highest values corresponding to continentally influenced air masses where sulfate aerosol surface mean diameters and surface area concentrations were the largest. Mass scattering efficiencies for submicron sea salt were higher (averaging 4.2±0.96 m2 g−1) due to the tailing of coarse mode sea salt into the particle size range most efficient for light scattering. Given the similar lifetimes of submicron non‐sea‐salt sulfate and sea salt in the marine boundary layer, it is evident that sea salt controls the aerosol optical properties in this Southern Ocean region.
A resilient transport network, which is significant for urban sustainability and security, is characterized by its ability to recover from disruptions subject to natural and man-made disasters. Bike ...sharing could act as a viable alternative in the case of public transit disruptions given its flexibility and various social, environmental, and economic benefits. This study aims to estimate quantitatively the potential of bike sharing to promote transport resilience, by using autoregressive negative binomial time series model to investigate the effects of public transit closures on bike sharing demand in Washington, D.C. area during 2015–2017. We find that (1) bike sharing can act as a supplementary mode to enhance urban transport resilience in the case of complete transit closure; (2) the proximity of bike sharing docks to metro stations has a powerful effect on propensity to use a bike sharing program; and (3) extreme weather is one of major barriers to bicycling. Planners can enhance resilience of urban transport networks by fully considering the capacity and usage of bike sharing docks, as well as the coherence of metro stations and bike sharing docks, in distributing and rebalancing activities.
Striking levels of spatial organization exist among and within interphase cell chromosomes, raising the possibility that other nuclear molecular components may also be organized in ways that ...facilitate nuclear function. To further examine molecular distributions and organization within cell nuclei, we utilized Raman spectroscopy to map distributions of molecular components, with a focus on cellular lipids. Although the vast majority of cellular lipids are associated with membranes, mapping the 2870/2850 cm−1 lipid peak ratios revealed that the most highly ordered lipids within interphase cells are found within cell nuclei. This finding was seen in cells from multiple tissue types, noncancerous cells, and in cancer cell lines of different metastatic potential. These highly ordered lipids colocalize with nuclear chromatin, are present throughout the nuclear volume, and remain colocalized with chromatin through mitosis, when the nuclear envelope has dissociated. Phosphatidylinositol is a major component of the highly ordered lipids. The presence of phosphatidylinositol and other lipids in the nuclear interior is well established, but their highly ordered packing has not been reported and represents a unique finding. The molecular interactions involved in the formation and maintenance of these highly ordered lipids, and their potential effects on nuclear activities, remain to be discovered.
The nonferrous metals industry (NMI) consumes a great amount of energy, and is a typical high CO2 emission sector. The NMI is one of the eight most concerning industries in the Intergovernmental ...Panel on Climate Change (IPCC) Fifth Assessment Report. In this study, we summarized policies that impact Chinese NMI's development and grouped them into three types: energy structure policies, energy efficiency improving policies and production-scale policies. Based on those quantitative policy goals, a bottom-up model has been developed to study the CO2 emissions of five NMI's major sub-sectors from 2010 to 2030. The results showed that if China's central government could stick to the CO2 reduction policy strength of 13th Five-Year Plan (2016–2020), then the copper, lead and zinc industries can reach their emissions peak before 2030. Furthermore, if the Chinese government restricts the production of primary aluminum of 46.2 million tons in 2025, then the CO2 emissions of China's non-ferrous industry could reach the peak in that year, when the CO2 emissions peak is 297 million tons. Having benefited from the effective CO2 reduction policies of NMI, China may reach its ambitious CO2 peaking goals more easily.
•We model the policy impacts on non-ferrous metals industry (NMI) ’s CO2 reduction based on decomposition method.•Direct and indirect CO2 emission are considered in the study.•CO2 emission of Chinese NMI is very likely to peak before 2030 under current policies.•Chinese energy efficiency policies of NMI should be updated.
In the past few years, shared bicycles have become a major form of green transport. There are two types of shared bicycle systems: pile-based and pile-less. These two types of systems have different ...carbon emission profiles when it comes to manufacture, operation and maintenance, and disposal. This research explicates these trade-offs through a thorough life cycle assessment of Capital Bikes' shared bikes in Washington D.C., USA. Our research indicates that while the installation of platforms and docks is the primary source of carbon emissions for dockless bikes, fleet management and maintenance are the primary sources of emissions for these vehicles. This is significant because the literature has shown that both dockless bikes and piling systems boost the resilience of transportation networks during pandemics or transport outages, albeit in different ways, when consumers may choose to utilize dockless bikes for exercise or to avoid using public transport. Planners should encourage proactive maintenance and fleet management to boost environmental advantages, as manufacturing operations generate five times as much carbon emissions as disposal activities. This study contrasted the Total Normal Environmental Impact (TNEI) of a dockless system with that of a piling system in our case study. The manufacturing process of a shared bicycle produces the largest amount of carbon emissions. The carbon dioxide emissions saved by a bicycle are about 0.07 kg per day. We also demonstrate that a net decrease in emissions in the Capital Bikes case study requires that each bike be utilized for a minimum of 591 days. In order to guarantee that the carbon emissions produced by shared bicycles are optimised, travelers should be incentivized to ride for longer and firms should strive to extend the usable life of their equipment.
•Original and comprehensive bike sharing data set is used.•Assessment of carbon dioxide emissions for the dockless and station–based bike sharing systems.•Estimation of the time shared bikes will take to balance the emissions through replacing vehicles
Autoantibodies to diverse antigens escape regulation in systemic lupus erythematosus under the influence of a multitude of predisposing genes. To gain insight into the differential impact of diverse ...genetic backgrounds on tolerance mechanisms controlling autoantibody production in lupus, we established a single lupus-derived nephritis associated anti-basement membrane Ig transgene on each of four inbred murine lupus strains, including BXSB, (NZBxNZW)F1, NZB, and MRL/lpr, as approved by the Duke University and the Durham Veterans Affairs Medical Centers' Animal Care and Use Committees. In nonautoimmune C57BL/6 mice, B cells bearing this anti-laminin Ig transgene are stringently regulated by central deletion, editing, and anergy. Here, we show that tolerance is generally intact in unmanipulated Ig transgenic BXSB, (NZBxNZW)F1, and NZB mice, based on absence of serum transgenic anti-laminin autoantibodies and failure to recover spontaneous anti-laminin monoclonal antibodies. Four- to six-fold depletion of splenic B cells in transgenic mice of these strains, as well as in MRL/lpr transgenic mice, and reduced frequency of IgM+ bone marrow B cells suggest that central deletion is grossly intact. Nonetheless the 4 strains demonstrate distinct transgenic B cell phenotypes, including endotoxin-stimulated production of anti-laminin antibodies by B cells from transgenic NZB mice, and in vitro hyperproliferation of both endotoxin- and BCR-stimulated B cells from transgenic BXSB mice, which are shown to have an enrichment of CD21-high marginal zone cells. Rare anti-laminin transgenic B cells spontaneously escape tolerance in MRL/lpr mice. Further study of the mechanisms underlying these strain-specific B cell fates will provide insight into genetic modification of humoral autoimmunity in lupus.
Celotno besedilo
Dostopno za:
DOBA, IJS, IZUM, KILJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
•Original and comprehensive bike sharing data set is used.•Assesses the effect of the COVID-19 pandemic on shared bicycle user behaviour.•Illustrates how bike sharing offers supports resilience in ...transport networks.
Globally most governments implemented a ‘Working from Home’ (home office) strategy to contain the spread of the coronavirus in 2020 in order to ensure public safety and minimize the transmission of the virus. Unsurprisingly studies have found that COVID-19 has had a detrimental impact on urban transportation systems; however, the number of shared bicycle riders is progressively growing compared to other modes of public transit. The aim of this study is to investigate the influence of COVID-19 on the usage of shared bicycle systems in order to identify passenger travel patterns and habits. In addition, bicycle rentals are becoming more popular in some locations. This demonstrates that bike sharing as a transport option has a high level of social adaptability and is progressively being adopted by the general population in a fashion that promotes the resilience of transport systems.
The purpose of the current study was to describe the perceptions and experiences of New Horizons Band assistants in terms of learning, skill transfer and pedagogical preparation. The participant ...population for this study was 35 past student teacher-assistants from three New Horizons
bands, one in Texas, one in Florida and one in Virginia. There were ten open-ended items on the questionnaire that asked about student assistant perceptions and experiences. Participants noted the growth they experienced from serving as a band teaching assistant in a New Horizons programme,
describing their appreciation for lifelong learning, exposure to the complexity of how to teach to a variety of learners, and experience with the challenges of pacing with adults and blunt feedback from programme participants. The article concludes with a discussion of possible collegiate
preparatory experiences that could broaden the teacher training experience for college programmes.
PDF
