Emission Ratio Research Articles

Influence of polyvinylpyrrolidone (PVP) in the synthesis of luminescent NaYF4:Yb,Er upconversion nanoparticles

Polyvinylpyrrolidone (PVP) can be used to produce upconversion nanoparticles (UCNPs) in an advantageous manner, i.e. at modest temperatures in open-to-air conditions with simple hotplate and flask apparatus. However, the influence of PVP parameters on the formation of UCNPs has not been previously investigated. In this exploratory study, we establish that PVP molecular weight and relative amount of PVP can greatly influence the morphology and diameter of NaYF4:Yb,Er UCNPs produced via the PVP-assisted route. At nominal amounts of PVP, varying the molecular weight of PVP in synthesis between 10,000 g mol−1 (PVP10), 40,000 g mol−1 (PVP40), and 55,000 g mol−1 (PVP55), had minimal effect on UCNP morphology, whereas reducing the quantity of PVP10 and PVP40 in the reaction to 10% of the nominal amount resulted in two notable effects: (1) the generation of a greater range of UCNP diameters and (2) the production of an unexpected sub-population of rhombus-shaped UCNPs. Bulk and individual nanoparticle analysis indicates that all UCNP morphologies were cubic (α-phase) crystal structure and consisted of NaYF4:Yb,Er. Optical emission properties exhibited only modest green and red luminescence emission ratio when PVP parameters were varied. However, separately produced PVP40 NaYF4:Yb,Tm UCNPs exhibited a much more intense and dual-band blue/red emission. This exploratory work demonstrates that tailoring PVP content in synthesis of UCNPs can greatly alter morphology of UCNPs produced and should be carefully considered in experimental design. However, the underlying mechanisms of action of the role PVP plays in this synthesis remain unclear. Ultimately, significant further work is still required to fully elucidate the relevant chemistry to achieve full control of PVP-UCNP synthesis.

Inverse Modeling of Formaldehyde Emissions and Assessment of Associated Cumulative Ambient Air Exposures at Fine Scale

Among air toxics, formaldehyde (HCHO) is an important contributor to urban cancer risk. Emissions of HCHO in the United States are systematically under-reported and may enhance atmospheric ozone and particulate matter, intensifying their impacts on human health. During the 2021 Michigan-Ontario Ozone Source Experiment (MOOSE), mobile real-time (~1 s frequency) measurements of ozone, nitrogen oxides, and organic compounds were conducted in an industrialized area in metropolitan Detroit. The measured concentrations were used to infer ground-level and elevated emissions of HCHO, CO, and NO from multiple sources at a fine scale (400 m horizontal resolution) based on the 4D variational data assimilation technique and the MicroFACT air quality model. Cumulative exposure to HCHO from multiple sources of both primary (directly emitted) and secondary (atmospherically formed) HCHO was then simulated assuming emissions inferred from inverse modeling. Model-inferred HCHO emissions from larger industrial facilities were greater than 1 US ton per year while corresponding emission ratios of HCHO to CO in combustion sources were roughly 2 to 5%. Moreover, simulated ambient HCHO concentrations depended significantly on wind direction relative to the largest sources. The model helped to explain the observed HCHO concentration gradient between monitoring stations at Dearborn and River Rouge in 2021.

Exceptional Wildfire Enhancements of PAN, C2H4, CH3OH, and HCOOH Over the Canadian High Arctic During August 2017

AbstractExtreme enhancements in the total columns of carbon monoxide (CO), peroxyacetyl nitrate (PAN), ethylene (C2H4), methanol (CH3OH), and formic acid (HCOOH) were observed over the Canadian high Arctic during the period of 17–22 August 2017 by a ground‐based Fourier transform infrared (FTIR) spectrometer at Eureka, Nunavut (80.05°N, 86.42°W), and by the Infrared Atmospheric Sounding Interferometer (IASI) satellite instruments. These enhancements have been attributed to wildfires in British Columbia (BC) and the Northwest Territories (NWT) of Canada, and represent the largest short‐term perturbations of PAN, C2H4, and HCOOH above ambient concentrations over the 14‐year (2006–2020) Eureka time‐series. Enhancement ratios, emission ratios, and emission factors relative to CO were calculated for all species for both FTIR and IASI observations. The C2H4 and HCOOH emission factors are significantly larger than previous studies, suggesting unusually high emissions from these fires. The wildfire plumes were also simulated using the GEOS‐Chem model. Initial GEOS‐Chem simulations displayed a severe under‐estimation relative to observations for these fire plumes resulting from the injection height scheme of the model. Sensitivity tests highlighted that injection heights of 12.5 km for BC (based on previous studies) and 10 km for the NWT fires yielded the strongest correlations with ground‐based measurements. Applying these injection heights to the model significantly improves the simulated plume transport and agreement with ground‐ and space‐based observations. GEOS‐Chem was also used to estimate the magnitude of secondary in‐plume production of CH3OH and HCOOH; it was found to be an important component (∼18%) of the enhanced HCOOH columns at Eureka.

Characterization of chemical components of fresh and aged aerosol from vehicle exhaust emissions in Hong Kong

The chemical properties of fresh and aged aerosol emitted during controlled vehicular exhaust emissions were characterized in the analysis. Pyrene (10417.1 ± 534.9 ng kg−1) is the most abundant of all analyzed compounds in total fresh emission and succinic acid (57359.8 ± 4000.3 ng kg−1) is for the total aged emission. The fresh emission factors (EFfresh) of all compounds in the n-alkanes group demonstrate higher average emissions for the two vehicles with EURO 3 standard compared to the other vehicles. The EFfresh for benzo [a]pyrene is in descending order: G1 (183.1 ± 144.7 ng kg−1) > G3 (103.4 ± 60.1 ng kg−1) > G4 (91.2 ± 80.1 ng kg−1) > G2 (88.6 ± 93.9 ng kg−1). Aged/fresh (A/F) emission ratios (>20) confirmed that these diacid compounds are generated by the photooxidation of primary pollutants that emitted from gasoline combustions. High A/F ratios (>200) in phthalic acid, isophthalic acid and terephthalic acid under idling mode imply relatively more intense photochemical reactions for their productions compared with other chemical groups. Strong positive correlations (r > 0.6) were observed between the degradation of toluene and formations of pinonic acid, succinic acid, adipic acid, terephthalic acid, glutaric acid and citramalic acid after the aging process, suggesting possible photooxidation of toluene that can lead to secondary organic aerosol (SOA) formation in the urban atmosphere. The findings demonstrate that vehicle emission standards for pollution in relation to the change of particulate matter chemical compositions and SOA formations. The results warrant a need for regulated reformulation for such vehicles.

Analysis of the National Annual Emission of Pollutants from Road Transport in Poland in the Years 1990–2020

This article presents the official results of the inventory of pollutants in Poland from road transport, developed in the National Centre for Emissions Management of the Institute of Environmental Protection–National Research Institute in Warsaw as part of the reporting of national pollutant emissions. Considerations concern pollutants harmful to the health of living organisms. Source information is available in official reports. The national emission of pollutants covers the years of balancing 1990–2020. The aim of the work is to assess the dynamic properties of the processes of national emission of pollutants. The list of substances whose emission is examined in the article is consistent with the list of substances in accordance with the European Monitoring and Evaluation Programme/European Environment Agency (EMEP/EEA) procedure. These are pollutants harmful to the health of living organisms. The inventory of pollutants contributing to the intensification of the greenhouse effect in the atmosphere is carried out as part of separate reports. The energy consumption of road vehicles was presented. The ratio of national annual emissions of pollutants in 2020 and in 1990 is the lowest for sulfur oxides and lead, followed by non-methane volatile organic compounds and carbon monoxide. The analysis of the national pollutant emission concerned the energy emission factor, which characterizes the ecological level of the accumulated category of road vehicles. This is an original element, not seen before in world literature and official reports of research institutes. An unambiguous trend of decreasing the energy emission factor of pollutants, apart from ammonia, was found, which is related to the use of catalytic flue gas purification systems. This is confirmed by the analysis of the ratio of the energy emission factor in 2020 and 1990, as well as the relative derivative of the energy emission factor in relation to the national annual emission of pollutants.

Numerical study of NH3/CH4 MILD combustion with conjugate heat transfer model in a down-fired lab-scale furnace

Ammonia (NH3) is a promising carbon-free fuel but suffers from low flame stability and high NO emission. Moderate or intense low-oxygen dilution (MILD) combustion has been indicated to be a feasible technology for resolving these drawbacks of NH3 during its combustion. However, the effect of NH3 substitution on combustion and NO emission characteristics as well as heat transfer behaviors under MILD combustion is not well-understood. This paper reports a numerical study of NH3/CH4 combustion in a laboratory-scale furnace by using conjugate heat transfer (CHT) model, which eliminates the commonly-used fixed-temperature or fixed-heat flux assumptions for furnace walls. Main emphasis is laid on the comparison of NO emission, temperature distribution, flame structure and furnace heat transfer behaviors between traditional swirling combustion and MILD combustion under various NH3 blending ratio (XNH3) conditions. The results show that NO emission reaches to the maximum at XNH3 of 50% regardless of combustion mode., while MILD combustion generates a lower NO emission and conversion ratio than swirling combustion in the whole range of XNH3 (0% - 100%). Numerical simulation without using CHT model produces negative heat transfer in certain furnace regions, indicating the necessity of adopting CHT model on simulating heat transfer process in combustion furnaces. With the CHT model, the heat flux on the furnace wall is found to follow the same trend between the two different combustion modes, but the heat utilization efficiency of MILD combustion is slightly lower mainly due to the increased exhausted gas temperature, which is resulted from the postponed reaction zone. With the replacement of CH4 by NH3, the heat utilization efficiency gradually decreases under both two combustion modes as a result of lower peak temperature and less soot radiation.

Visual Scoring of Sacroiliac Joint/Sacrum Ratios of Single-Photon Emission Computed Tomography/Computed Tomography Images Affords High Sensitivity and Negative Predictive Value in Axial Spondyloarthritis.

Spondyloarthritis (SpA) is characterized by inflammatory back pain. Magnetic resonance imaging (MRI) was the earlier gold standard technique for detecting early inflammatory change. We reassessed the diagnostic utility of sacroiliac joint/sacrum (SIS) ratios of single-photon emission computed tomography/computed tomography (SPECT/CT) for identifying sacroiliitis. We aimed to investigate of SPECT/CT in diagnosing SpA using a rheumatologist's visual scoring of SIS ratios assessment. We conducted a single-center, medical records review study of patients with lower back pain who underwent bone SPECT/CT from August 2016 to April 2020. We employed semiquantitative visual bone scoring methods of SIS ratio. The uptake of each sacroiliac joint was compared to that of the sacrum (0-2). A score of 2 for the sacroiliac joint of either side was considered diagnostic of sacroiliitis. Of the 443 patients assessed, 40 had axial SpA (axSpA), 24 being radiographic axSpA and 16 being nonradiographic axSpA. The sensitivity, specificity, and positive and negative predictive values of SIS ratio of SPECT/CT for axSpA were 87.5%, 56.5%, 16.6%, and 97.8%, respectively. In receiver operating curve analysis, MRI better diagnosed axSpA than did SIS ratio of SPECT/CT. Although the diagnostic utility of SIS ratio of SPECT/CT was inferior to MRI, visual scoring of SPECT/CT affords high sensitivity and negative predictive value in axSpA. When MRI is inappropriate for certain patients, SIS ratio of SPECT/CT is an alternative tool for identifying axSpA in real practice.

Ozone response modeling to NOx and VOC emissions: Examining machine learning models

Current machine learning (ML) applications in atmospheric science focus on forecasting and bias correction for numerical modeling estimations, but few studies examined the nonlinear response of their predictions to precursor emissions. This study uses ground-level maximum daily 8-hour ozone average (MDA8 O3) as an example to examine O3 responses to local anthropogenic NOx and VOC emissions in Taiwan by Response Surface Modeling (RSM). Three different datasets for RSM were examined, including the Community Multiscale Air Quality (CMAQ) model data, ML-measurement-model fusion (ML-MMF) data, and ML data, which respectively represent direct numerical model predictions, numerical predictions adjusted by observations and other auxiliary data, and ML predictions based on observations and other auxiliary data.The results show that both ML-MMF (r = 0.93–0.94) and ML predictions (r = 0.89–0.94) present significantly improved performance in the benchmark case compared with CMAQ predictions (r = 0.41–0.80). While ML-MMF isopleths exhibit O3 nonlinearity close to actual responses due to their numerical base and observation-based correction, ML isopleths present biased predictions concerning their different controlled ranges of O3 and distorted O3 responses to NOx and VOC emission ratios compared with ML-MMF isopleths, which implies that using data without support from CMAQ modeling to predict the air quality could mislead the controlled targets and future trends. Meanwhile, the observation-corrected ML-MMF isopleths also emphasize the impact of transboundary pollution from mainland China on the regional O3 sensitivity to local NOx and VOC emissions, which transboundary NOx would make all air quality regions in April more sensitive to local VOC emissions and limit the potential effort by reducing local emissions.Future ML applications in atmospheric science like forecasting or bias correction should provide interpretability and explainability, except for meeting statistical performance and providing variable importance. Assessment with interpretable physical and chemical mechanisms and constructing a statistically robust ML model should be equally important.

Assessment of light-duty versus heavy-duty diesel on-road mobile source emissions using general additive models applied to traffic volume and air quality data and COVID-19 responses

ABSTRACT Following the outbreak of the COVID-19 pandemic, several papers have examined the effect of the pandemic response on urban air pollution worldwide. This study uses observed traffic volume and near-road air pollution data for black carbon (BC), oxides of nitrogen (NOx), and carbon monoxide (CO) to estimate the emissions contributions of light-duty and heavy-duty diesel vehicles in five cities in the continental United States. Analysis of mobile source impacts in the near-road environment has several health and environmental justice implications. Data from the initial COVID-19 response period, defined as March to May in 2020, were used with data from the same period over the previous two years to develop general additive models (GAMs) to quantify the emissions impact of each vehicle class. The model estimated that light-duty traffic contributes 4–69%, 14–65%, and 21–97% of BC, NOx, and CO near-road levels, respectively. Heavy-duty diesel traffic contributes an estimated 26–46%, 17–63%, and −7–18% of near-road levels of the three pollutants. The estimated mobile source impacts were used to calculate NOx to CO and BC to NOx emission ratios, which were between 0.21–0.32 μg m−3 NOx (μg m−3 CO)−1 and 0.013–0.018 μg m−3 BC (μg m−3 NOx)−1. These ratios can be used to assess existing emission inventories for use in determining air pollution standards. These results agree moderately well with recent National Emissions Inventory estimates and other empirically-derived estimates, showing similar trends among the pollutants. However, a limitation of this study was the recurring presence of an implausible air pollution impact estimate in 41% of the site-pollutant combinations, where a vehicle class was estimated to account for either a negative impact or an impact higher than the total estimated pollutant concentration. The variations seen in the GAM estimates are likely a result of location-specific factors, including fleet composition, external pollution sources, and traffic volumes. Implications: Drastic reductions in traffic and air pollution during the lockdowns of the COVID-19 pandemic present a unique opportunity to assess vehicle emissions. A General Additive Modeling approach is developed to relate traffic levels, observed air pollution, and meteorology to identify the amount vehicle types contribute to near-road levels of traffic-related air pollutants (TRAPs), which is important for future emission regulation and policy, given the significant health and environmental justice implications of vehicle-related pollution along major roadways. The model is used to evaluate emission inventories in the near-road environment, which can be used to refine existing estimates. By developing a locally data-driven method to readily characterize impacts and distinguish between heavy and light duty vehicle effects, local regulations can be used to target policies in major cities around the country, thus addressing local health disbenefits and disparities occurring as a result of exposure to near-road air pollution.

Effects of Precipitation Variation on Annual and Winter Soil Respiration in a Semiarid Mountain Shrubland in Northern China

In response to global climate change, future precipitation changes are expected to profoundly influence soil respiration in arid and semiarid areas. However, few studies focus on CO2 emissions from soils undergoing precipitation changes in semiarid mountain shrublands in winter. A precipitation-manipulation experiment with three levels of precipitation (30% decreased precipitation (DP), ambient precipitation (AP), and 30% increased precipitation (IP)) was performed to examine the effects of variable precipitation on soil respiration (SR) and wintertime contributions to annual SR emissions in Vitex negundo var. heterophylla shrub ecosystems located on the Middle Taihang Mountain in Hebei Province, northern China. The results showed that the average annual SR rates and winter SR rates ranged from 1.37 to 1.67 μmol m−2 s−1 and 0.42 to 0.59 μmol m−2 s−1 among the different precipitation treatments. The model based on soil moisture better represented the soil-respiration rates, suggesting that the variable precipitation extended the water’s limitation of the soil’s CO2 emissions. The cumulative annual soil CO2 emissions were 523, 578, and 634 g C m−2 in response to the DP, AP, and IP treatments, respectively. The ratio of the soil CO2 emissions in winter to the annual CO2 emissions varied from 7.6 to 8.8% in response to the different precipitation treatments. Therefore, ignoring the soil CO2 emissions in winter leads to the underestimation of the carbon losses in semiarid shrublands. Our results highlight that variable precipitation significantly influences soil-respiration rates, and soil CO2 emissions in winter must not be ignored when predicting the future feedback between SR and climate change in semiarid regions.

High temperature-resistant flexible inorganic coating for aluminium silicate fiber cloth with low solar absorption ratio and high emissivity

To prepare a coating with a high emissivity and low solar absorption ratio on the surface of aluminum silicate fiber cloth, the sol-gel method was used with silica sol as a binder. In this study, the effects of two white fillers, titanium oxide and zirconia, on the substrate and radiation properties of coatings were compared after heat treatment at 800–1200 °C. The ZrO2-based coating had good stability after heat treatment at 800–1200 °C, and maintained its white color, exhibiting solar absorption ratio of approximately 0.14 and emissivity of 0.84. ZrO2-based coatings prevented harmful cracking, as observed for the TiO2-based coatings after heat treatment, because of the ZrO2 phase transformation. The ZrO2-based coating did not have strong bonding with the substrate, and the substrate strength was improved by maintaining a weak bonding interface. Compared with the TiO2-based coatings, which exhibit reduced substrate strength above 1000 °C, the ZrO2-based coating was more suitable for the surface of flexible fiber cloths as a temperature-resistant coating with good development prospects.

Ammonia masers towards G 358.931−0.030

ABSTRACT We report the detection of ammonia masers in the non-metastable (6, 3), (7, 5), and (6, 5) transitions; the latter being the first unambiguous maser detection of that transition ever made. Our observations include the first very long baseline interferometry detection of ammonia maser emission, which allowed effective constraining of the (6, 5) maser brightness temperature. The masers were detected towards G 358.931−0.030, a site of 6.7-GHz class II methanol maser emission that was recently reported to be undergoing a period of flaring activity. These ammonia masers appear to be flaring contemporaneously with the class II methanol masers during the accretion burst event of G 358.931−0.030. This newly detected site of ammonia maser emission is only the 12th such site discovered in the Milky Way. We also report the results of an investigation into the maser pumping conditions, for all three detected masing transitions, through radiative transfer calculations constrained by our observational data. These calculations support the hypothesis that the ammonia (6, 5) maser transition is excited through high colour temperature infrared emission, with the (6, 5) and (7, 5) transition line ratio implying dust temperatures >400 K. Additionally, we detect significant linearly polarized emission from the ammonia (6, 3) maser line. Alongside our observational and radiative transfer calculation results, we also report newly derived rest frequencies for the ammonia (6, 3) and (6, 5) transitions.

The light emission and in-plane polarization ratio of (0001) GaInN/GaN quantum well structures grown on a stripe-shaped cavity engineered sapphire substrate

The light emission and in-plane polarization ratio of (0001) GaInN/GaN quantum well structures grown on a stripe-shaped cavity engineered sapphire substrate

A Reaction-Based Ratiometric Bioluminescent Platform for Point-of-Care and Quantitative Detection Using a Smartphone.

Fluorescent probes have emerged as powerful tools for the detection of different analytes by virtue of structural tenability. However, the requirement of an excitation source largely hinders their applicability in point-of-care detection, as well as causing autofluorescence interference in complex samples. Herein, based on bioluminescence resonance energy transfer (BRET), we developed a reaction-based ratiometric bioluminescent platform, which allows the excitation-free detection of analytes. The platform has a modular design consisting of a NanoLuc-HaloTag fusion as an energy donor, to which a synthetic fluorescent probe is bioorthogonally labeled as recognition moiety and energy acceptor. Once activated by the target, the fluorescent probe can be excited by NanoLuc to generate a remarkable BRET signal, resulting in obvious color changes of luminescence, which can be easily recorded and quantitatively analyzed by a smartphone. As a proof of concept, a fluorescent probe for HOCl was synthesized to construct the bioluminescent system. Results demonstrated the system showed a constant blue/red emission ratio which is independent to the signal intensity, allowing the quantification of HOCl concentration with high sensitivity (limit of detection (LOD) = 13 nM) and accuracy. Given the universality, this reaction-based bioluminescent platform holds great potential for point-of-care and quantitative detection of reactive species.

Analysis of Energy Use Efficiency and Greenhouse Gas Emissions of Lemon (Citrus lemonL.) Production in Turkey.

The purpose of this study was to determine the energy use efficiency and greenhouse gas emissions of lemon production. It was performed during the 2019-2020 production period in Turkey. The agricultural inputs and outputs used in lemon production were calculated to determine the energy use efficiency and greenhouse gas emissions. According to study findings, the energy inputs in lemon production were calculated respectively as 16,046.98 MJha-1 (55.43%) chemical fertilizers energy, 4168.93 MJha-1 (14.40%) chemicals energy, 2815.20 MJha-1 (9.72%) electricity energy, 2740.42 MJha-1 (9.47%) diesel fuel energy, 1864.80 MJha-1 (6.44%) irrigation water energy, 705.67 MJha-1 (2.44%) machinery energy and 610.20 MJha-1 (2.11%) human labour energy. Total input energy and output energy were calculated as 28,952.20 MJha-1 and 60,165.40 MJha-1, respectively. Energy use efficiency, specific energy, energy productivity and net energy values were calculated respectively as 2.08, 0.91 MJkg-1, 1.09 kgMJ-1 and 31,213.20 MJha-1. The consumed total energy inputs in lemon production can be categorized as 27.74% direct, 72.26% indirect, 8.55% renewable and 91.45% non-renewable. Total greenhouse gas emissions were calculated as 2650.96 kgCO2‑eqha-1 for lemon production, with the greatest share for nitrogen 950.62 kgCO2‑eqha-1 (35.86%). Based on the study findings, it was concluded that lemon production in 2019-2020 production season was profitable in terms of energy use efficiency (2.08). Greenhouse gas emission ratio (per kg) was calculated as 0.08. This study is important since there is no study on the energy balance and greenhouse gas emissions in lemon production in Muğla province, Turkey.

High time-resolution fenceline air quality sensing and dispersion modeling for environmental justice-centered source attribution

Since compliance air monitoring networks have limited spatial coverage, low-cost air quality sensors (LCAQS) are being used to facilitate exposure assessment for environmental justice communities and investigating the effects from nearby emitters. This study illustrates an application of LCAQS at the Spring Valley High School (SVHS), located at the southern fenceline of an asphalt plant in Las Vegas, Nevada, from March through August 2019 to assess the plant's contributions to schoolchildrens' PM2.5 and PM10 exposure. A computational fluid dynamics (CFD)-based dispersion modeling found that the plant's emissions affected SVHS only for wind directions ranging from 270° to 112.5°. Within the wind sector, the plant's contributions at a 5-min resolution were estimated by the incremental PM concentrations between downwind and upwind senor measurements made at SVHS and a northern fenceline site, respectively. The method was able to attribute 3.7% of the PM2.5 and 11.8% of the PM10 at SVHS to the asphalt plant over the measurement period and estimate the plant's daily contributions that were up to 28% and 50% for PM2.5 and PM10, respectively. The contributions depended on wind speed, time of day, and day of week (weekday vs. weekend), consistent with emission activities from aggregate handling in such a facility. By coupling LCAQS and CFD results, an average PM10 emission rate of 0.58 g s−1 and PM10/PM2.5 emission ratio of 11 were derived for a 10 miles per hour (4.5 m s−1) wind speed. The emission rate and ratio agree, within 20%, with estimates from the U.S. National Emission Inventory. This study design may be applicable for environmental justice-centered monitoring projects with resource constraints, providing information for stakeholders to take necessary actions to address air quality concerns.

Aircraft and satellite observations reveal historical gap between top-down and bottom-up CO2 emissions from Canadian oil sands.

Measurement-based estimates of greenhouse gas (GHG) emissions from complex industrial operations are challenging to obtain, but serve as an important, independent check on inventory-reported emissions. Such top-down estimates, while important for oil and gas (O&G) emissions globally, are particularly relevant for Canadian oil sands (OS) operations, which represent the largest O&G contributor to national GHG emissions. We present a multifaceted top-down approach for estimating CO2 emissions that combines aircraft-measured CO2/NOx emission ratios (ERs) with inventory and satellite-derived NOx emissions from Ozone Monitoring Instrument (OMI) and TROPOspheric Ozone Monitoring Instrument (TROPOMI) and apply it to the Athabasca Oil Sands Region (AOSR) in Alberta, Canada. Historical CO2 emissions were reconstructed for the surface mining region, and average top-down estimates were found to be >65% higher than facility-reported, bottom-up estimates from 2005 to 2020. Higher top-down vs. bottom-up emissions estimates were also consistently obtained for individual surface mining and in situ extraction facilities, which represent a growing category of energy-intensive OS operations. Although the magnitudes of the measured discrepancies vary between facilities, they combine such that the observed reporting gap for total AOSR emissions is ≥(31 ± 8) Mt for each of the last 3 years (2018-2020). This potential underestimation is large and broadly highlights the importance of continued review and refinement of bottom-up estimation methodologies and inventories. The ER method herein offers a powerful approach for upscaling measured facility-level or regional fossil fuel CO2 emissions by taking advantage of satellite remote sensing observations.

A rationale for higher ratios of CH4 to CO2 production in warmer anoxic freshwater sediments and soils

A rationale for higher ratios of <scp>CH₄</scp> to <scp>CO₂</scp> production in warmer anoxic freshwater sediments and soils

Project-based sustainable timing series decision-making for pavement maintenance using multi-objective optimization: An innovation in traditional solutions

Pavement maintenance timing series (PMTS) optimization at the project level should consider multiple interventional maintenance impacts within the planning horizon, while making trade-offs between investment and environmental burden, which is difficult to address with traditional methods, partly due to the lack of understanding of the interaction mechanism between the sustainable objectives. To bridge this gap, this paper presents a customized project-based PTMS decision-making method using multi-objective optimization, and applied it to explore the PMTS generation mechanisms by decomposing the sustainable objectives. Results show that among the three sustainable objectives, life-cycle agency cost and greenhouse gas (GHG) emissions drive the timing series formation of maintenance technologies, and GHG emissions can also limit the “greedy” growth of non-zero decision variables, while the integral function form of the benefit of pavement maintenance can improve the lowest performance condition. In addition, the proposed approach allows for the maximization of the trade-offs between the three sustainable objectives using the Euclidean norm strategy, while providing a prioritized set of potential PMTS solutions. Based on that, a benefit-to-cost & GHG emissions ratio model (BCGRM) was proposed to compare with the above tri-objective optimization model in generating PMTS. Since the non-dominating nature of the three objectives cannot be directly considered, BCGRM will get higher investment benefits by increasing the maintenance frequency.

Mechanical Force-Induced Color-Variable Luminescence of Carbon Dots in Boric Acid Matrix.

Mechano-luminescent materials that exhibit distinct luminescence responses to force stimuli are urgently anticipated in view of application needs in the fields of sensing, anti-counterfeiting, optoelectronic devices, etc. However, most of the reported materials normally exhibit force-induced changes in luminescent intensity, whereas materials that possess force-induced color-variable luminescence remain rarely reported. Herein, for the first time, a novel mechanical force-induced color-variable luminescence material from carbon dots (CDs) in boric acid (CD@BA) is reported. At low CDs concentration, the luminescence of CD@BA exhibits a grinding-induced color variable from white to blue. This grinding-induced color variable can be switched to yellow-to-white changing by increasing the CDs concentration in BA. The grinding-induced color-variable luminescence originates from dynamic variation in emission ratio of fluorescence and room temperature phosphorescence, due to the influence of oxygen and water vapor in the air. At high CDs concentration, short-wavelength fluorescence undergoes more severe reabsorption compared to room temperature phosphorescence, leading to grinding-induced color-variable switching from white-to-blue to yellow-to-white. Based on the unique properties of CD@BA powder, the applications of recognizing and visualizing fingerprints on the surfaces of various of materials are demonstrated.