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It is necessary to evaluate the interactions between the different functional layers in optoelectronic devices to optimize device performance. Recently, the I-rich all-inorganic perovskite CsPbI2Br has attracted tremendous attention for use in solar cell applications because of its suitable band gap and favorable photo and thermal stabilities. It has been reported that the undesirable phase degradation of the photoactive α phase CsPbI2Br to the non-perovskite δ phase could be triggered by high humidity. To obtain stable devices, it is thus important to protect CsPbI2Br from moisture. In this paper, CuI, a non-hygroscopic p-type hole-transporting material, is found to induce the phase degradation of α-CsPbI2Br to the δ-CsPbI2Br. The rate and extent of phase degradation of CsPbI2Br are closely associated with the heating temperature and coverage of a CuI granular capping layer. This discovery is different from the widely reported water-induced phase degradation of CsPbI2Br. Our work highlights the importance of careful selection of hole-transporting materials during the processing of I-rich all-inorganic CsPbX3 (X=Br, I) perovskites to realize high-performance optoelectronic devices.

Abundances of a range of air pollutants can be inferred from satellite UV-Vis spectroscopy measurements by using the unique absorption signatures of gas species. Here, we implemented several spectral fitting methods to retrieve tropospheric NO2, SO2, and HCHO from the ozone monitoring instrument (OMI), with radiative simulations providing necessary information on the interactions of scattered solar light within the atmosphere. We analyzed the spatial distribution and temporal trends of satellite-observed air pollutants over eastern China during 2005–2017, especially in heavily polluted regions. We found significant decreasing trends in NO2 and SO2 since 2011 over most regions, despite varying temporal features and turning points. In contrast, an overall increasing trend was identified for tropospheric HCHO over these regions in recent years. Furthermore, generalized additive models were implemented to understand the driving forces of air quality trends in China and assess the effectiveness of emission controls. Our results indicated that although meteorological parameters, such as wind, water vapor, solar radiation and temperature, mainly dominated the day-to-day and seasonal fluctuations in air pollutants, anthropogenic emissions played a unique role in the long-term variation in the ambient concentrations of NO2, SO2, and HCHO in the past 13 years. Generally, recent declines in NO2 and SO2 could be attributed to emission reductions due to effective air quality policies, and the opposite trends in HCHO may urge the need to control anthropogenic volatile organic compound (VOC) emissions., Air pollution: satellite sees significant trends in China Satellite-based observations of air pollution in China reveal a recent declining trend in the levels of nitrogen dioxide (NO2) and sulfur dioxide (SO2), but rising levels of formaldehyde (HCHO). Chengxin Zhang and colleagues at the University of Science and Technology of China, with co-workers at other Chinese research centers, analyzed ultraviolet-visible spectroscopy data from the Ozone Monitoring Instrument of NASA’s EOS-Aura satellite. Meteorological effects such as winds, temperature and humidity caused day-to-day and seasonal fluctuations, but human activity appears responsible for long term trends. Declines in NO2 and SO2 levels occurred from 2011, across most regions, and are attributed to effective air quality policies. The rising trend in HCHO levels suggests that new measures may be needed to control the release by human activities of that and other volatile organic compounds.

This paper introduces a novel additive-manufacturing technique to obtain high-resolution selective-ink-deposition on complex 3-D objects, packages, and modules for 5G applications. The technique consists of embossing the desired pattern directly on the 3-D printed dielectric surface and then applying ink with a suitable tool. This approach is tested in combination with stereolithography 3-D printing technology to obtain selectively metallized 3-D circuits. In particular, the “clear” resin from FormLab is utilized for the 3-D printed dielectric, while the metallization is performed with silver nanoparticle ink from Suntronic. As a preliminary study, test samples containing lines with different widths are manufactured, demonstrating a pitch down to $135~\mu \text {m}$ and satisfactory sheet resistance of $0.011~\Omega /\text {sq.}$ (the electromagnetic characterization of the dielectric resin is reported in the Appendix). Then, two broadband multiport RF structures are developed to show the versatility of the proposed technology. First, an ultrawideband 3-D crossover, operating in the range 100 MHz–5 GHz, is conceived to test the suitability of the proposed technology to perform selective metallization on curved semienclosed areas. Then, the technology is applied to a multiple-input–multiple-output (MIMO) antenna system, based on four proximity-fed annular slot antennas, arranged on the lateral sides of a cube and decoupled by introducing a cross-shaped structure in the interior of the cube. This circuit offers a broad range of metallization challenges, as it features embossed and engraved parts, high-resolution patterns (line widths down to 0.7 mm) and sharp edges. Each slot radiates unidirectionally with the same polarization and uses the cube and its internal cross-shaped structure as a resonant cavity. The antenna system is designed to operate in the band 3.4–3.8 GHz, which is one of the sub-6-GHz 5G bands in Europe, and it is thought for hotspot and access-point applications. The final antenna topology is composed of only two blocks, weighs 21.29 g, and occupies a volume of $44.4\times 45.8\times 45.8\,\,\text {mm}^{3}$ , featuring an envelope correlation coefficient (ECC) lower than 0.005 and a total active reflection coefficient (TARC) lower than −6 dB in all the bands of interests.

In this paper, we present a quantitative determination of the NOx emission in Hefei using mobile Multi-Axis Differential Optical Absorption Spectroscopy (MAX-DOAS) measurements. The measurements were carried out during winter time from December 2016 to February 2017. The measured NO2 vertical column densities (VCDs) show a strong spatial gradient with higher values within the city center, indicating the majority of NOx emission sources are located at the city center. A significant “holiday effect” was found by comparing measurements taken during weekdays and weekend. The weekend reduction is more significant in the suburban (∼28%) compared to the city center (∼13%). Mobile measurements of NO2 vertical column densities (VCDs) were analyzed together with meteorological data to determine the NOx emission by applying the loop-integral method. Detailed error analysis of the NOx emission shows the variation of wind field and large measurement gap dominated the total error of NOx emission calculation. The result shows the NOx emission in Hefei during winter time varies in a wide range from 10 × 1024 to 40 × 1024molecs−1 with an average of 18.44 × 1024molecs−1. Our estimation is about 43% lower than the number reported in the previous emission inventory in 2012. The reduction of NOx emission reflects the successful implementation of emission control measures in recent years. Our result also shows about 73% of the total NOx in the city were transported from outside of the city during winter. The impacts of transported NOx are especially large when air masses originated from heavily polluted regions, i.e. North China Plain and Yangtze River Delta. The result presented provides a better understanding of the impacts of local emissions and transportation of pollutants on the local air quality of Hefei.

Restrictions on human activities remarkably reduced emissions of air pollutants in China during the COVID-19 lockdown periods. However, distinct responses of O3 concentrations were observed across China. In the Beijing–Tianjin–Hebei (BTH) and Yangtze River Delta (YRD) regions, O3 concentrations were enhanced by 90.21 and 71.79% from pre-lockdown to lockdown periods in 2020, significantly greater than the equivalent concentrations for the same periods over 2015–2019 (69.99 and 43.62%, p &lt, 0.001). In contrast, a decline was detected (−1.1%) in the Pearl River Delta (PRD) region. To better understand the underlying causes for these inconsistent responses across China, we adopted the least absolute shrinkage and selection operator (Lasso) and ordinary linear squares (OLS) methods in this study. Statistical analysis indicated that a sharp decline in nitrogen dioxide (NO2) was the major driver of enhanced O3 in the BTH region as it is a NOx-saturated region. In the YRD region, season-shift induced changes in the temperature/shortwave radiative flux, while lockdown induced declines in NO2, attributable to the rise in O3. In the PRD region, the slight drop in O3 is attributed to the decreased intensity of radiation. The distinct regimes of the O3 response to the COVID-19 lockdown in China offer important insights into different O3 control strategies across China.

In this paper, we present the Hefei EMI Cloud Retrieval Algorithm (HECORA), which uses information from the O2-O2 absorption band around 477 nm to retrieve effective cloud fraction and effective cloud pressure from satellite observations. The retrieved cloud information intends to improve the atmospheric trace gas products based on the Environment Monitoring Instrument (EMI) spectrometer. The HECORA method builds on OMCLDO2 and presents some evolutions. The Vector Linearized Discrete Ordinate Radiative Transfer (VLIDORT) model has been used to produce the Top of the Atmosphere (TOA) reflectance Look-up Tables (LUT) as a function of the cloud fraction and cloud pressure. Applying the Differential Optical Absorption Spectroscopy (DOAS) technique to the synthetic reflectance LUT, the reflectance spectra can be associated with O2-O2 geometrical vertical column densities (VCDgeo) and continuum reflectance. This is the core of the retrieval method, since there is a one-to-one relationship between O2-O2 VCDgeo and continuum reflectance, on the one hand, and effective cloud fraction and effective cloud pressure, on the other hand, for a given illumination and observing geometry and given surface height and surface albedo. We first used the VLIDORT synthetic spectra to verify the HECORA algorithm and obtained good results in both the Lambertian cloud model and the scattering cloud model. Secondly, HECORA is applied to OMI and TROPOMI and compared with OMCLDO2, FRESCO+, and OCRA/ROCINN cloud products. Later, the cloud pressure results from TROPOMI observations obtained using HECORA and FRESCO+ are compared with the CALIOP Cloud Layer product. HECORA is closer to the CALIOP results under low cloud conditions, while FRESCO+ is closer to high clouds due to the higher sensitivity of the O2 A-band to cloud vertical information. Finally, HECORA is applied to the TROPOMI NO2 retrieval. Validation of the tropospheric NO2 VCD with ground-based MAX-DOAS measurements shows that choosing HECORA cloud products to correct for photon path variations on the TROPOMI tropospheric NO2 VCD retrievals has better performance than using FRESCO+ under low cloud conditions. In conclusion, this paper shows that the HECORA cloud products are in good agreement with the well-established cloud products and that they are suitable for correcting the effect of cloud in trace gas retrievals. Therefore, HECORA has the potential to be applied to EMI., Remote Sensing, 12 (18), ISSN:2072-4292

Wireless sensors are pervasive today for applications spanning environmental sensing, safety, health, structural integrity, smart homes, and smart cities. Implementations of wireless sensor networks and Internet of Things (IoT) systems have typically relied on power supplied by batteries, which have a limited lifetime and pose the increased burden on users of replacing or manually recharging them to keep devices up and running.

The Environmental trace gas Monitoring Instrument (EMI) onboard the Chinese high-resolution remote sensing satellite GaoFen-5 is an ultraviolet-visible imaging spectrometer, aiming to quantify the global distribution of tropospheric and stratospheric trace gases and planned to be launched in spring 2018. The preflight calibration phase is essential to characterize the properties and performance of the EMI in order to provide information for data processing and trace gas retrievals. In this paper, we present the first EMI measurement of nitrogen dioxide (NO 2 ) from a gas absorption cell using scattered sunlight as the light source by the differential optical absorption spectroscopy technique. The retrieved NO 2 column densities in the UV and Vis wavelength ranges are consistent with the column density in the gas cell calculated from the NO 2 mixing ratio and the length of the gas cell. Furthermore, the differences of the retrieved NO 2 column densities among the adjoining spatial rows of the detector are less than 3%. This variation is similar to the well-known “stripes-pattern” of the Ozone Monitoring Instrument and is probably caused by remaining systematic effects like a nonperfect description of the individual instrument functions. Finally, the signal-to-noise ratios of EMI in-orbit measurements of NO 2 are estimated on the basis of on-ground scattered sunlight measurements and radiative transfer model simulations. Based on our results, we conclude that the EMI is capable of measuring the global distribution of the NO 2 column with the retrieval precision and accuracy better than 3% for the tested wavelength ranges and viewing angles.

Recently, atmospheric ozone pollution has demonstrated an aggravating tendency in China. To date, most research about atmospheric ozone has been confined near the surface, and an understanding of the vertical ozone structure is limited. During the 2016 G20 conference, strict emission control measures were implemented in Hangzhou, a megacity in the Yangtze River Delta, and its surrounding regions. Here, we monitored the vertical profiles of ozone concentration and aerosol extinction coefficients in the lower troposphere using an ozone lidar, in addition to the vertical column densities (VCDs) of ozone and its precursors in the troposphere through satellite-based remote sensing. The ozone concentrations reached a peak near the top of the boundary layer. During the control period, the aerosol extinction coefficients in the lower lidar layer decreased significantly; however, the ozone concentration fluctuated frequently with two pollution episodes and one clean episode. The sensitivity of ozone production was mostly within VOC-limited or transition regimes, but entered a NOx-limited regime due to a substantial decline of NOx during the clean episode. Temporary measures took no immediate effect on ozone pollution in the boundary layer; instead, meteorological conditions like air mass sources and solar radiation intensities dominated the variations in the ozone concentration.

By combining radio-frequency identification (RFID) and paper-microfluidics technologies, a low-cost first-of-its-kind platform for comprehensive liquid sensing, i.e., the “smart test strip,” is presented, which enables portable wireless real-time liquid sensing with handhold devices (e.g., cell phones), and integration of various multifunctional electrical and chemical sensors, for numerous Lab-on-Chip applications, including manufacturing control, environmental monitoring, and point-of-care medical diagnostics. The fabrication of RFID tags and two types of microfluidics are accomplished by a single inkjet-printing process in a cost-effective environmental-friendly additive manufacturing approach, which makes possible the production of disposable, lightweight, and flexible sensing platforms. Taking advantage of the proposed smart test strips platforms, we demonstrate two proof-of-concept high-performance electrical sensors based on interdigitated electrode topologies: a resistivity-based sensor with a 1782 $\Omega$ /( $\Omega$ *m) sensitivity; nevertheless, the proposed permittivity-based sensor with a 15%/ $\epsilon _r$ sensitivity, but the proposed integrated wireless platform, can facilitate the integration of even more chemical and electrical sensors. In addition, two on-strip antenna prototypes have been designed, optimized, and tested to work at 2.4 GHz and 13.56 MHz, respectively. Furthermore, the wireless interrogation of a complete proof-of-concept smart test strip is presented, which shows an excellent sensing resolution of 1.33 $\Omega$ over the range of 0–1371 $\Omega$ .

Formaldehyde (HCHO) in the ambient air not only causes cancer but also is an ideal indicator for volatile organic compounds (VOCs) which are major precursors of ozone (O3) and secondary organic aerosol (SOA) near the surface. It is meaningful to differentiate between direct emission and secondary formation for HCHO pollution control and sensitivity study of O3 production. However, the understanding of the sources of HCHO is still poor in China, due to limited measurements of HCHO in the field, both spatially and temporally. In this study, tropospheric HCHO vertical column densities (VCDs) in the Yangtze River Delta (YRD), East China where HCHO pollution is serious were retrieved from Ozone Mapping and Profiler Suite (OMPS) onboard the Suomi National Polar-orbiting Partnership (Suomi-NPP) satellite from 2014 to 2017, and kept good agreement with the tropospheric HCHO columns measured by ground-based high resolution Fourier transform infrared spectrometry (FTS) with the correlation coefficient (R) of 0.78. Based on this, the cancer risk was estimated nationwide and in the YRD region. At least, 7840 people in the YRD region would develop cancer in their lives due to outdoor HCHO exposure, which occupied 23.4 % of total national cancer risk. Besides, the contributions of primary and secondary sources were apportioned, combining with primary and secondary tracers from surface observation. Overall, HCHO from secondary formation contributed most to ambient HCHO and can be regarded as the indication of the VOCs reactivity in Hangzhou and urban areas of Nanjing and Shanghai from 2015 to 2017, due to strong correlation between total HCHO and secondary HCHO. At industrial sites in Nanjing, primary emission influenced most to ambient HCHO in 2015 and showed an obvious decreasing trend. Seasonally, HCHO from secondary formation reached the maximum in summer and minimum in winter. In the spring, summer, and autumn, secondary formation played a curial effect on variation of ambient HCHO in urban regions of Nanjing, Hangzhou, and Shanghai; while in the winter the contribution from secondary formation became less significant. The understanding of the variation of the primary and secondary contributions to ambient HCHO is in favor for a better understanding the role of HCHO in atmospheric chemistry and formulating effective control measures to decrease HCHO pollution and cancer risk.

Recently, the occurrence of fog and haze over China has increased. The retrieval of trace gases from the multi-axis differential optical absorption spectroscopy (MAX-DOAS) is challenging under these conditions. In this study, various reported retrieval settings for formaldehyde (HCHO) and sulfur dioxide (SO2) are compared to evaluate the performance of these settings under different meteorological conditions (clear day, haze, and fog). The dataset from 1st December 2019 to 31st March 2020 over Nanjing, China, is used in this study. The results indicated that for HCHO, the optimal settings were in the 324.5–359 nm wavelength window with a polynomial order of five. At these settings, the fitting and root mean squared (RMS) errors for column density were considerably improved for haze and fog conditions, and the differential slant column densities (DSCDs) showed more accurate values compared to the DSCDs between 336.5 and 359 nm. For SO2, the optimal settings for retrieval were found to be at 307–328 nm with a polynomial order of five. Here, root mean square (RMS) and fitting errors were significantly lower under all conditions. The observed HCHO and SO2 vertical column densities were significantly lower on fog days compared to clear days, reflecting a decreased chemical production of HCHO and aqueous phase oxidation of SO2 in fog droplets.

Air quality is strongly influenced by both local emissions and regional transport. Atmospheric chemical transport models can distinguish between emissions and regional transport sources in air pollutant concentrations. However, quantifying model inventories is challenging due to emission changes caused by the recent strict control measures taken by the Chinese government. In this study, we use NO2 column observations from the Tropospheric Monitoring Instrument to retrieve top-down nitrogen oxide (NOX) emissions and quantify the contributions of local emissions and regional transport to NOx in Beijing (BJ), from 1 November 2018 to 28 February 2019 (W_2018) and 1 November 2019 to 29 February 2020 (W_2019). In W_2018 and W_2019, the BJ bottom-up NOX emissions from the multi-resolution emission inventory for China in 2017 were overestimated by 11.8% and 40.5%, respectively, and the input of NOX from other cities to BJ was overestimated by 10.9% and 51.6%, respectively. The simulation using our adjusted inventory exhibited a much higher spatial agreement (slope = 1.0, R2 = 0.79) and reduced a mean relative error by 45% compared to those of bottom-up NOX emissions. The top-down inventory indicated that (1) city boundary transport contributes approximately 40% of the NOX concentration in BJ; (2) in W_2019, NOX emissions and transport in BJ decreased by 20.4% and 17.2%, respectively, compared to those of W_2018; (3) in W_2019, NOX influx substantially decreased (−699 g/s) in BJ compared to that of W_2018 despite negative meteorological conditions that should have increased NOx influx by +503 g/s. Overall, the contribution of intercity input to NOx in BJ has declined with decreasing emissions in the surrounding cities due to regional cooperative control measures, and the role of local emissions in BJ NOx levels was more prominent. Our findings indicate that local emissions may play vital roles in regional center city air quality.

To explore the changes of pyrolysis behaviors from xylophyta to herbage, pyrolysis properties of red pepper stalks (RPS) as a representative kind of biomass of high lignin content of agricultural residues were studied by using TGA and Py-GC/MS. The results indicated that contents of cellulose, 43.2 wt.%, and of lignin, 24.7 wt.% were higher than those of corn stalks, wheat stalks and cotton stalks, but closer to those of the poplar wood. The pyrolysis process mainly occurred in three stages, and with an increasing heating rate from 10 °C/min to 30 °C/min, the TGA curves shifted to a lower temperature. With an increase in pyrolysis temperature, the contents of sugars, phenols and furans decreased from 3.96%, 13.54% and 10.13% to 1.09%, 7.13% and 1.65%, respectively. The contents of hydroxyacetaldehyde and acetone reached a maximum 13.71% and 20.05% at 500 °C. At 300 °C levoglucose, pentanal and methyl furan content reached maxima of 3.63%, 13.09% and 7.49%, respectively. Different chemical components could account for the changes of pyrolytic behaviors from xylophyta to herbage.

In this study, the spatiotemporal distribution of the NO2 and SO2 Vertical Columns Densities (VCDs) in the North China Plain (NCP) region was measured by long-distance mobile measurements using a mobile Multi-AXis Differential Optical Absorption Spectroscopy (MAX-DOAS) instrument. The mobile observations were performed in both summer (July 2017) and winter (January and February 2018) and the total driving mileage exceeded 3000 km. The concentrations of NO2 and SO2 in different seasons and areas were significantly different. During winter, serious NO2 and SO2 pollution was observed in northern Anhui Province, central Shandong Province, and the Beijing-Tianjin-Hebei Region. The evolution and transportation processes of three typical heavy pollution cases were discussed in detail. Combined with the Weather Research and Forecasting with Chemistry model simulated wind field information, the NO2 transportation flux from northern Jiangsu Province to northern Anhui Province is quantified as 7.12 kg s−1. Finally, we estimated the NO2 and SO2 emissions from the Dezhou and Hengshui power plants by plume cross section scanning and encircled observations, respectively. The NO2 and SO2 emission fluxes of the Dezhou Power Plant are 0.79 kg s−1 and 1.11 kg s−1, respectively, while the NO2 and SO2 emission fluxes of the Hengshui Power Plant are 0.12 kg s−1 and 0.36 kg s−1, respectively. This study quantitatively analyzed the transportation of atmospheric pollutants and power plant emissions, which is helpful for understanding the occurrence and evolution of pollution and is also useful for the government to introduce policies to protect and control the atmospheric environment.

In this study, ship-based multi-axis differential optical absorption spectroscopy (MAX-DOAS) measurements were performed in the East China Sea (ECS) area in June 2017. The tropospheric slant column densities (SCDs) of nitrogen dioxide (NO2), sulfur dioxide (SO2), and formaldehyde (HCHO) were retrieved from the measured spectra using the differential optical absorption spectroscopy (DOAS) technique. Using the simple geometric approach, the SCDs of different trace gases observed at a 15∘ elevation angle were adopted to convert into tropospheric vertical column densities (VCDs). During this campaign, the averaged VCDs of NO2, SO2, and HCHO in the marine environment over the ECS area are 6.50×1015, 4.28×1015, and 7.39×1015 molec cm−2, respectively. In addition, the ship-based MAX-DOAS trace gas VCDs were compared with satellite observations of the Ozone Monitoring Instrument (OMI) and Ozone Mapping and Profiler Suite (OMPS). The daily OMI NO2 VCDs agreed well with ship-based MAX-DOAS measurements showing the correlation coefficient R of 0.83. In addition, the good agreements of SO2 and HCHO VCDs between the OMPS satellite and ship-based MAX-DOAS observations were also found, with correlation coefficients R of 0.76 and 0.69. The vertical profiles of these trace gases are achieved from the measured differential slant column densities (DSCDs) at different elevation angles using the optimal estimation method. The retrieved profiles displayed the typical vertical distribution characteristics, which exhibit low concentrations of

A precise knowledge of ozone seasonal evolution and photochemical production regime in polluted troposphere in China has important policy implications for ozone pollution controls especially in megacities where ozone pollution is common throughout the year. In this study, we used tropospheric ozone, CO and HCHO columns derived from high resolution Fourier transform infrared spectrometry (FTS) in Hefei, China, tropospheric NO2 columns deduced from overpass Ozone Monitoring Instrument (OMI), surface meteorological data, and a back trajectory cluster analysis technique to investigate ozone seasonal evolution and photochemical production regime in eastern China from 2014–2017. A pronounced seasonal cycle for tropospheric ozone is captured by FTS, where high levels of tropospheric ozone occurs in spring and summer, and low levels of tropospheric ozone occurs in autumn and winter. Day-to-day variations in spring and summer are in most cases larger than those in autumn and winter. At the same time, it shows that the tropospheric ozone roughly increases over time at the first half year and reaches the maximum in June, and then it decreases over time at the second half year. Tropospheric ozone columns in June are, on average, 0.5×1018 molecules*cm−2 (47.6 %) higher than those in December which has a mean value of 1.05×1018 molecules*cm−2. The OMI time series shows similar behaviour. The measured features can basically be reproduced by GEOS-Chem and WRF-Chem data but with slight shifts in the timing of the seasonal maximum. Back trajectories analysis shows that: air pollutions in megacities in central-southern China, northwest China, and the key pollution area, i.e., Yangtze River Delta area in eastern China, dominates the contributions to the observed tropospheric ozone levels, while the contributions from the other two key pollution areas, i.e., Beijing-Tianjin-Hebei in north China and Pearl River Delta in south China, are very small; Air masses generated from polluted areas have more transportations to the observed area in spring and summer than in autumn and winter, and hence have more contributions to the observed tropospheric ozone levels. Correlations between tropospheric ozone and meteorological data disclosed that spring and summer is more favorable to photochemical ozone production than in autumn and winter. Finally, the HCHO/NO2 ratio is used as a proxy to investigate the chemical sensitivity of ozone production (PO3). The results show that the PO3 is mainly NOx limited in summer, while it is mainly VOC or mix VOC-NOx limited in winter. Statistics show that NOx limited, mix VOC-NOx limited, and VOC limited PO3 accounts for 60.1 %, 28.7 %, and 11 %, respectively.

Ground based Multi-Axis Differential Optical Absorption Spectroscopy (MAX-DOAS) and lidar measurements were performed in Shanghai, China during May 2016 to investigate the summertime atmospheric pollutants vertical distribution. In this study, vertical profiles of aerosol extinction coefficient, nitrogen dioxide (NO2) and formaldehyde (HCHO) concentrations were retrieved from MAX-DOAS measurement using the Heidelberg Profile (HeiPro) algorithm, while vertical distribution of ozone (O3) was obtained from an ozone lidar. Sensitivity study of the MAX-DOAS aerosol profile retrieval shows that the a priori aerosol profile shape has significant influences on the aerosol profile retrieval. Aerosol profiles retrieved from MAX-DOAS measurements with Gaussian a priori demonstrate the best agreements with simultaneous lidar measurements and vehicle-based tethered-balloon observations among all a priori aerosol profiles. MAX-DOAS measured tropospheric NO2Vertical Column Densities (VCDs) show a good agreement with OMI satellite observations with Pearson correlation coefficient (R) of 0.95. In addition, measurements of the O3 vertical distribution indicate that the ozone productions do not only occur at surface level but also at higher altitudes (about 1.1 km). Planetary boundary layer (PBL) height, horizontal and vertical wind fields information were integrated to discuss the ozone formation at upper altitudes. The results reveal that enhanced ozone concentrations at ground and upper altitudes are not directly related to horizontal and vertical transportations. Similar patterns of O3 and HCHO vertical distributions were observed during this campaign, which implies that the ozone productions near to the surface and at higher altitudes are mainly influenced by the abundance of volatile organic compounds (VOCs) in the lower troposphere.

This paper presents a novel approach to realize 3D-printed flexible reconfigurable antennas, along with a proof-of-concept tunable bow-tie antenna inspired from Chinese origami fan. Stereolithography (SLA) printing, a low-cost high-performance additive manufacturing technique, is utilize to enable the easy fabrication of origami structure prototypes and the structure is metallized using a liquid metal alloy (LMA) to facilitate folding without breakages. The proposed bow-tie antenna features a frequency tuning range from 896 MHz to 992 MHz and bandwidth reconfigurability. This reconfigurable antenna can be applied to various dynamically changing scenarios such as wireless communications, collapsible/portable radars, wearable applications.

We present the trend and seasonal variability of stratospheric NO2 column for the first time over the polluted atmosphere at Hefei, China, retrieved using Fourier transform infrared spectroscopy (FTIR) between 2015 and 2018. The FTIR observed stratospheric NO2 columns over Hefei show a peak in June and reach a minimum in January. The mean stratospheric NO2 column concentration in June is (3.49 ± 0.25) × 1015 molecules*cm−2, and is 39.20% ± 8.95% higher than that in January with a mean value of (2.51 ± 0.21) × 1015 molecules*cm−2. We find a negative trend of (−0.34 ± 0.05) %/yr in the FTIR observations of stratospheric NO2 column. The FTIR data are compared to the satellite OMI observations to assess the new data set quality and also applied to evaluate the GEOS-Chem model simulations. We find in general the OMI observations and GEOS-Chem model results are in good agreement with the coincident FTIR data, and they all show similar seasonal cycles with strong correlation coefficients of 0.84-0.86. The annual average OMI minus FTIR difference is (1.48 ± 5.33) × 1014 molecules*cm−2 (4.82% ± 17.37%), and average GEOS-Chem minus FTIR difference is (2.36 ± 2.33) × 1014 molecules*cm −2 (7.66% ± 7.49%). Their maximum differences occur in April and May with mean differences of 12-16%. We also found negative trends in the stratospheric NO2 column over Hefei for 2015-2018 with both OMI observations (−0.91 ± 0.09%/yr) and GEOS-Chem model results (−0.31 ± 0.05%/yr), demonstrating some consistency among them.

As the needs for low-cost rapidly-produced microfluidics are growing with the trend of Lab-on-a-Chip and distributed healthcare, the fully inkjet-printing of microfluidics can be a solution to it with numerous potential electrical and sensing applications. Inkjet-printing is an additive manufacturing technique featuring no material waste and a low equipment cost. Moreover, similar to other additive manufacturing techniques, inkjet-printing is easy to learn and has a high fabrication speed, while it offers generally a great planar resolution down to below 20 µm and enables flexible designs due to its inherent thin film deposition capabilities. Due to the thin film feature, the printed objects also usually obtain a high vertical resolution (such as 4.6 µm). This paper introduces a low-cost rapid three-dimensional fabrication process of microfluidics, that relies entirely on an inkjet-printer based single platform and can be implemented directly on top of virtually any substrates.

A bio-enabled, environmentally-friendly, and maximally mild layer-by-layer approach has been developed to surface modify inherently hydrophobic Kapton HN substrates to allow for great printability of both water- and organic solvent-based inks thus facilitating the full-inkjet-printing of flexible electronic devices. Different from the traditional Kapton surface modification approaches which are structure-compromising and use harsh conditions to target, and oxidize and/or remove part of, the surface polyimide of Kapton, the present Kapton surface modification approach targeted the surface electric charges borne by its additive particles, and was not only the first to utilize environmentally-friendly clinical biomolecules to build up a thin film of protamine-heparin complex on Kapton, but also the first to be conducted under minimally destructive and maximally mild conditions. Besides, for electrically charged ink particles, the present surface modification method can enhance the uniformity of the inkjet-printed films by reducing the “coffee ring effect”. As a proof-of-concept demonstration, reduced graphene oxide-based gas sensors, which were flexible, ultra-lightweight, and miniature-sized, were fully-inkjet-printed on surface modified Kapton HN films and tested for their sensitivity to dimethyl methylphosphonate (a nerve agent simulant). Such fabricated sensors survived a Scotch-tape peel test and were found insensitive to repeated bending to a small 0.5 cm radius.

This paper proposes the first-of-its-kind microfluidics-based encodable and flexible chipless RFID sensors. The prototype, including the microfluidic channels and passive RFID resonators, is manufactured cost-efficiently with sole reliance on multilayer inkjet-printing for the first time. Three microfluidics-based reconfigurable spiral resonators are used to obtain tunable “code” frequencies and encode the RFID with less than 0.5 µL of water per bit. The embedded microfluidics also facilitate sensing of various fluids (e.g. identifying different water-glycerol mixtures). The proposed chipless RFID module maintains a stable performance during bending and can be bent for radii down to at least 12 mm. The proposed encodable chipless RFID module can be used in various application spaces including healthcare monitoring, food quality sensing and liquid leakage detection.