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The step-stitching issue occurring in digital micromirror device (DMD)-based step lithography, which refers to overlapping and misalignment, has dramatically influenced the overall accuracy of the exposed patterns. To address this technical challenge, this paper proposes a testing method to resolve the system tolerance parameters, inclination angle with 0.060^∘±0.003^∘, and magnification with 3.60399±0.00020, which induce the stitching problem. With these two parameters, a compensation strategy on motion is implemented to precisely control the step distance of the stage so that the edge-to-edge stitching error is reduced to about 0.150 µm and the corner-to-corner stitching error is less than 0.500 µm. The changes of the linewidth induced by the displacement error due to the stage control accuracy and illumination nonuniformity caused by the light source are simulated and analyzed, and the image preprocessing method based on a gradual grayscale mask is employed to improve the quality of stitching. Using this method, the linewidth difference is controlled to be within 0.150 µm. After finishing all the corrections and imaging preprocessing, the transverse error has become almost invisible, and the longitudinal error has been reduced by 97.72%. Experimental results demonstrate that the improved stitching accuracy could achieve high-fidelity devices.

China has implemented strong incentives to promote the market penetration of plug-in electric vehicles (PEVs). In this study, we compare the well-to-wheels (WTW) greenhouse gas (GHG) emission intensities of PEVs with those of gasoline vehicles at the provincial level in the year 2017 by considering the heterogeneity in the consumption-based electricity mix and climate impacts on vehicle fuel economy. Results show a high variation of provincial WTW GHG emission intensities for battery electric vehicles (BEVs, 22–293 g CO2eq/km) and plug-in hybrid electric vehicles (PHEVs, 82–298 g CO2eq/km) in contrast to gasoline internal combustion engine vehicles (ICEVs, 227–245 g CO2eq/km) and gasoline hybrid electric vehicles (HEVs, 141–164 g CO2eq/km). Due to the GHG-intensive coal-based electricity and cold weather, WTW GHG emission intensities of BEVs and PHEVs are higher than those of gasoline ICEVs in seven and ten northern provinces in China, respectively. WTW GHG emission intensities of gasoline HEVs, on the other hand, are lower in 18 and 26 provinces than those of BEVs and PHEVs, respectively. The analysis suggests that province-specific PEV and electric grid development policies should be considered for GHG emission reductions of on-road transportation in China.

In this paper, we propose spatiotemporal modulation projection lithography (STPL) technology, which is a spatiotemporal modulation technology applied to the conventional digital micromirror device (DMD) projection lithography system. Through coordinating the micro-movement of the piezoelectric stage, the flexible pattern generation of DMD, and the exposure time, the proposed STPL enables us to fabricate a microstructure with smooth edges, accurate linewidth, and accurate line position. Further application on fabricating a diffraction lens has been implemented. The edge sawtooth of the Fresnel zone plate fabricated by using the STPL is reduced to 0.3 µm, the error between the actual measured linewidth and the ideal linewidth is only within ±0.1µm, and the focal length is 15 mm, which is basically consistent with the designed focal length. These results indicated that STPL can serve a significant role in the micromanufacturing field for achieving high-fidelity microdevices.

The TROPOspheric Monitoring Instrument (TROPOMI) is used to derive top-down NOXemissions for two large power plants and three megacities in North America. We first re-process the vertical column NO2with an improved air mass factor to correct for a known systematic low bias in the operational retrieval near urban centers. For the two power plants, top-down NOXemissions agree to within 10% of the emissions reported by the power plants. We then derive top-down NOXemissions rates for New York City, Chicago, and Toronto, and compare them to projected bottom-up emissions inventories. In this analysis of 2018 NOXemissions, we find a +22% overestimate for New York City, a −21% underestimate in Toronto, and good agreement in Chicago in the projected bottom-up inventories when compared to the top-down emissions. Top-down NOXemissions also capture intraseasonal variability, such as the weekday versus weekend effect (emissions are +45% larger on weekdays versus weekends in Chicago). Finally, we demonstrate the enhanced capabilities of TROPOMI, which allow us to derive a NOXemissions rate for Chicago using a single overpass on July 7, 2018. The large signal-to-noise ratio of TROPOMI is well-suited for estimating NOXemissions from relatively small sources and for sub-seasonal timeframes.

The global and U.S. domestic effort to develop a clean energy economy and curb environmental pollution incentivizes the use of hydrogen as a transportation fuel, owing to its zero tailpipe pollutant emissions and high fuel efficiency in fuel cell electric vehicles (FCEVs). However, the hydrogen production process is not emissions free. Conventional hydrogen production via steam methane reforming (SMR) is energy intensive, coproduces carbon dioxide, and emits air pollutants. Thus, it is necessary to quantify the environmental impacts of SMR hydrogen production alongside the use-phase of FCEVs. This study fills the information gap, analyzing the greenhouse gas (GHG) and criteria air pollutant (CAP) emissions associated with hydrogen production in U.S. SMR facilities by compiling and matching the facility-reported GHG and CAP emissions data with facilities’ hydrogen production data. The actual amounts of hydrogen produced at U.S. SMR facilities are often confidential. Thus, we have developed four approaches to estimate the hydrogen production amounts. The resultant GHG and CAP emissions per MJ of hydrogen produced in individual facilities were aggregated to develop emission values for both a national median and a California state median. This study also investigates the breakdown of facility emissions into combustion emissions and noncombustion emissions.

Using Greenhouse Gas Reporting Program data (GHGRP) and National Emissions Inventory data from 2014, we investigate U.S. refinery greenhouse gas (GHG) emissions (CO2, CH4, and N2O) and criteria air pollutant (CAP) emissions (VOC, CO, NOx, SO2, PM10, and PM2.5). The study derives (1) combustion emission factors (EFs) of refinery fuels (e.g., refinery catalyst coke and refinery combined gas), (2) U.S. refinery GHG emissions and CAP emissions per crude throughput at the national and regional levels, and (3) GHG and CAP emissions attributable to U.S. refinery products. The latter two emissions were further itemized by source: combustion emission, process emission, and facility-wide emission. We estimated U.S. refinery product GHG and CAP emissions via energy allocation at the refinery process unit level. The unit energy demand and unit flow information were adopted from the Petroleum Refinery Life Cycle Inventory Model (PRELIM version 1.1) by fitting individual U.S. refineries. This study fills an important information gap because it (1) evaluates refinery CAP emissions along with GHG emissions and (2) provides CAP and GHG emissions not only for refinery main products (gasoline, diesel, jet fuel, etc.) but also for refinery secondary products (asphalt, lubricant, wax, light olefins, etc.).

Millions of people die every year from diseases caused by exposure to outdoor air pollution. Some studies have estimated premature mortality related to local sources of air pollution, but local air quality can also be affected by atmospheric transport of pollution from distant sources. International trade is contributing to the globalization of emission and pollution as a result of the production of goods (and their associated emissions) in one region for consumption in another region. The effects of international trade on air pollutant emissions, air quality and health have been investigated regionally, but a combined, global assessment of the health impacts related to international trade and the transport of atmospheric air pollution is lacking. Here we combine four global models to estimate premature mortality caused by fine particulate matter (PM2.5) pollution as a result of atmospheric transport and the production and consumption of goods and services in different world regions. We find that, of the 3.45 million premature deaths related to PM2.5pollution in 2007 worldwide, about 12 per cent (411,100 deaths) were related to air pollutants emitted in a region of the world other than that in which the death occurred, and about 22 per cent (762,400 deaths) were associated with goods and services produced in one region for consumption in another. For example, PM2.5pollution produced in China in 2007 is linked to more than 64,800 premature deaths in regions other than China, including more than 3,100 premature deaths in western Europe and the USA; on the other hand, consumption in western Europe and the USA is linked to more than 108,600 premature deaths in China. Our results reveal that the transboundary health impacts of PM2.5pollution associated with international trade are greater than those associated with long-distance atmospheric pollutant transport.

International trade separates regions consuming goods and services from regions where goods and related aerosol pollution are produced. Yet the role of trade in aerosol climate forcing attributed to different regions has never been quantified. Here, we contrast the direct radiative forcing of aerosols related to regions’ consumption of goods and services against the forcing due to emissions produced in each region. Aerosols assessed include black carbon, primary organic aerosol, and secondary inorganic aerosols, including sulfate, nitrate and ammonium. We find that global aerosol radiative forcing due to emissions produced in East Asia is much stronger than the forcing related to goods and services ultimately consumed in that region because of its large net export of emissions-intensive goods. The opposite is true for net importers such as Western Europe and North America: global radiative forcing related to consumption is much greater than the forcing due to emissions produced in these regions. Overall, trade is associated with a shift of radiative forcing from net importing to net exporting regions. Compared to greenhouse gases such as carbon dioxide, the short atmospheric lifetimes of aerosols cause large localized differences between consumption- and production-related radiative forcing. International efforts to reduce emissions in the exporting countries will help alleviate trade-related climate and health impacts of aerosols while lowering global emissions.

Three-dimensional (3D) printing is widely used in many fields such as micro-optics, microbiology, and microfluidics. However, using existing technologies is a challenge to efficiently fabricate high-quality 3D structures with cross-scale and cross-precision. In this paper, we propose a low-cost hybrid processing technology that combines two-photon polymerization (TPP) and DMD micro stereolithography (DMDMSL) (TPP-DMDMSL). This low-cost hybrid processing technology is a two-part alignment achieved by combining marker positioning and image processing, and then by coordinating the transformation of processing data. Using the same mark as a bridge, the two independent technologies are linked to realize hybrid processing. The high synergetic combination of the two technologies is realized by using the mask as the benchmark and combining it with the flexible real-time transformation of processing data. The horizontal and vertical alignment accuracy is 2 µm and 3 µm, respectively. TPP-DMDMSL unites the high precision of TPP with the high efficiency of DMDMSL. Taking the aspheric lens as an example (radius = 163 µm, height = 33 µm), TPP-DMDMSL reduces the time from 4 h to 1 h. The maximum surface error is 0.22 µm, which does not affect the image quality according to the Rayleigh criterion. TPP-DMDMSL manufactures different types of structures. These results prove that TPP-DMDMSL can print multiple types of 3D structures across scales and precision, which is challenging or time-consuming with existing technologies. TPP-DMDMSL will likely be extended to more micro and nano fields based on the original general technology. TPP-DMDMSL provides strong basic techniques and ideas for integrated hybrid processing systems in the future.

TROPOMI satellite data show substantial drops in nitrogen dioxide (NO2) during COVID‐19 physical distancing. To attribute NO2changes to NOxemissions changes over short timescales, one must account for meteorology. We find that meteorological patterns were especially favorable for low NO2in much of the United States in spring 2020, complicating comparisons with spring 2019. Meteorological variations between years can cause column NO2differences of ~15% over monthly timescales. After accounting for solar angle and meteorological considerations, we calculate that NO2drops ranged between 9.2% and 43.4% among 20 cities in North America, with a median of 21.6%. Of the studied cities, largest NO2drops (>30%) were in San Jose, Los Angeles, and Toronto, and smallest drops (<12%) were in Miami, Minneapolis, and Dallas. These normalized NO2changes can be used to highlight locations with greater activity changes and better understand the sources contributing to adverse air quality in each city. Nitrogen dioxide (NO2) is an air pollutant whose prevalence in urban areas is linked to fossil fuel combustion. The NO2in our atmosphere is primarily a function of the magnitude of nitrogen oxide (NOx) emissions and weather factors such as sun angle, wind speed, and temperature. In this work, we developed two novel methods to account for weather impacts on daily pollution levels during COVID‐19 precautions. Once we accounted for favorable weather conditions that in some cases kept air pollution low independent of tailpipe emissions, calculated air pollutant emission reductions varied dramatically (9–43%) among 20 North American cities. Results can be used to understand factors contributing to inconsistent NO2changes during physical distancing, which can inform the effectiveness of COVID‐19 protocols and aid future policy development. These methodologies will allow us to respond more quickly in future unintended experiments when emissions change suddenly. Meteorological patterns were especially favorable for low NO2in much of the United States in spring 2020, complicating comparisons with spring 2019Weather variations between years can cause column NO2differences of ~15% over monthly timescalesNO2drops attributed to COVID‐19 lockdowns ranged between 9.2% and 43.4% among 20 cities in North America, with a median of 21.6%