Low Detection Limit Circularly Polarized Light Detection Realized by Constructing Chiral Perovskite/Si Heterostructures.

Chiral perovskites have been demonstrated as promising candidates for direct circularly polarized light (CPL) detection due to their intrinsic chirality and excellent charge transport ability. However, chiral perovskite-based CPL detectors with both high distinguishability of left- and right-handed optical signals and low detection limit remain unexplored. Here, a heterostructure, (R-MPA)2 MAPb2 I7 /Si (MPA = methylphenethylamine, MA = methylammonium) is constructed, to achieve high-sensitive and low-limit CPL detection. The heterostructures with high crystalline quality and sharp interface exhibit a strong built-in electric field and a suppressed dark current, not only improving the separation and transport of the photogenerated carriers but also laying a foundation for weak CPL signals detection. Consequently, the heterostructure-based CPL detector obtains a high anisotropy factor up to 0.34 with a remarkably low CPL detection limit of 890 nW cm-2 under the self-driven mode. As a pioneering study, this work paves the way for designing high-sensitive CPL detectors that simultaneously have great distinguishing capability and low detection limit of CPL.

Improving spatial resolution and diagnostic confidence with thinner slice and deep learning image reconstruction in contrast-enhanced abdominal CT.

OBJECTIVE: To evaluate image quality and diagnostic confidence improvement using a thin slice and a deep learning image reconstruction (DLIR) in contrast-enhanced abdominal CT. METHODS: Forty patients with hepatic lesions in enhanced abdominal CT were retrospectively analyzed. Images in the portal phase were reconstructed at 5 mm and 1.25 mm slice thickness using the 50% adaptive statistical iterative reconstruction (ASIR-V) (ASIR-V50%) and at 1.25 mm using DLIR at medium (DLIR-M) and high (DLIR-H) settings. CT number and standard deviation of the hepatic parenchyma, spleen, portal vein, and subcutaneous fat were measured, and contrast-to-noise ratio (CNR) was calculated. Edge-rise-slope (ERS) was measured on the portal vein to reflect spatial resolution and the CT number skewness on liver parenchyma was calculated to reflect image texture. Two radiologists blindly assessed the overall image quality including subjective noise, image contrast, visibility of small structures using a 5-point scale, and object sharpness and lesion contour using a 4-point scale. RESULTS: For the 1.25-mm images, DLIR significantly reduced image noise, improved CNR and overall subjective image quality compared to ASIR-V50%. Compared to the 5-mm ASIR-V50% images, DLIR images had significantly higher scores in the visibility and contour for small structures and lesions; as well as significantly higher ERS and lower CT number skewness. At a quarter of the signal strength, the 1.25-mm DLIR-H images had a similar subjective noise score as the 5-mm ASIR-V50% images. CONCLUSION: DLIR significantly reduces image noise and maintains a more natural image texture; image spatial resolution and diagnostic confidence can be improved using thin slice images and DLIR in abdominal CT. KEY POINTS: • DLIR further reduces image noise compared with ASIR-V while maintaining favorable image texture. • In abdominal CT, thinner slice images improve image spatial resolution and small object visualization but suffer from higher image noise. • Thinner slice images combined with DLIR in abdominal CT significantly suppress image noise for detecting low-density lesions while significantly improving image spatial resolution and overall image quality.

Unanswered questions on the airborne transmission of COVID-19.

Policies and measures to control pandemics are often failing. While biological factors controlling transmission are usually well explored, little is known about the environmental drivers of transmission and infection. For instance, respiratory droplets and aerosol particles are crucial vectors for the airborne transmission of the severe acute respiratory syndrome coronavirus 2, the causation agent of the coronavirus 2019 pandemic (COVID-19). Once expectorated, respiratory droplets interact with atmospheric particulates that influence the viability and transmission of the novel coronavirus, yet there is little knowledge on this process or its consequences on virus transmission and infection. Here we review the effects of atmospheric particulate properties, vortex zones, and air pollution on virus survivability and transmission. We found that particle size, chemical constituents, electrostatic charges, and the moisture content of airborne particles can have notable effects on virus transmission, with higher survival generally associated with larger particles, yet some viruses are better preserved on small particles. Some chemical constituents and surface-adsorbed chemical species may damage peptide bonds in viral proteins and impair virus stability. Electrostatic charges and water content of atmospheric particulates may affect the adherence of virion particles and possibly their viability. In addition, vortex zones and human thermal plumes are major environmental factors altering the aerodynamics of buoyant particles in air, which can strongly influence the transport of airborne particles and the transmission of associated viruses. Insights into these factors may provide explanations for the widely observed positive correlations between COVID-19 infection and mortality with air pollution, of which particulate matter is a common constituent that may have a central role in the airborne transmission of the novel coronavirus. Supplementary Information: The online version contains supplementary material available at 10.1007/s10311-022-01557-z.

Unprecedented Chiral Three-dimensional Hybrid Organic-Inorganic Perovskitoids.

Chiral three-dimensional hybrid organic-inorganic perovskites (3D HOIPs) would show unique chiroptoelectronic performance due to the combination of chirality and 3D structure. However, the synthesis of 3D chiral HOIPs remains a significant challenge. Herein, we constructed a pair of unprecedented 3D chiral halide perovskitoids (R/S-BPEA)EA6 Pb4 Cl15 (1-R/S) (R/S-BPEA=(R/S)-1-4-Bromophenylethylammonium, EA=ethylammonium), in which the large chiral cations can be contained in the big "hollow" inorganic frameworks induced by mixing cations. Notably, 3D 1-R/S shows natural chiroptical activity, as evidenced by its significant mirror circular dichroism spectra and the ability to distinguish circularly polarized light. Moreover, based on the unique 3D structure, 1-S presents sensitive X-ray detection performance with a low detection limit of 398 nGyair s-1 , which is 14 times lower than the regular medical diagnosis of 5.5 µGyair s-1 . In this work, 3D chiral halide perovskitoids provide a new route to develop chiral material in spintronics and optoelectronics.

Real-time chemical composition of ambient fine aerosols and related cytotoxic effects in human lung epithelial cells in an urban area.

Particulate matter with aerodynamic diameters ≤1 µm (PM1) in the atmosphere, especially that which is emitted from anthropogenic sources, can induce considerable negative effects on the cardiopulmonary system. To investigate the chemical emission characteristics and organic sources in Yuen Long (Hong Kong), both offline and online approaches for PM1 samples were applied by filter-based samplers and a Quadrupole Aerosol Chemical Speciation Monitor (Q-ACSM), respectively. The toxicological effects on human A549 lung alveolar epithelial cells were investigated, and associations between cytotoxicity and organic sources and compositions were evaluated. The organics from the Q-ACSM measurement were the largest contributor to submicron aerosols in both seasons of our study, and the mass fraction was higher in winter (60%) than it was in autumn (46%). Regarding organic sources, the mass fraction of hydrocarbon-like organics (HOA) increased from 7% in autumn to 38% in winter, whereas cooking organics (COA) decreased from 30% in autumn to 18% in winter, and oxygenated organics (OOA) decreased from 63% to 45%. Organic compounds contributed more during pollution episodes, and more secondary ions were formed by means of the oxidation process. Oxidative and inflammatory responses in A549 cells were found with PM1 exposures; the differences in chemical compositions resulted in the higher cytotoxicity in winter than autumn. The cooking organic aerosol in residential area was significantly correlated with cell inflammation. Both elemental carbon and specific inorganic ions (SO42- and Mg2+) contributed to the intracellular cytotoxicity. This study demonstrated that specific atmospheric particulate matter chemical properties and sources can trigger distinct cell reactions; the inorganic ions from cooking emissions cannot be disregarded in terms of their pulmonary health risks in residential areas.

Image quality improvement in low-dose chest CT with deep learning image reconstruction.

OBJECTIVES: To investigate the clinical utility of deep learning image reconstruction (DLIR) for improving image quality in low-dose chest CT in comparison with 40% adaptive statistical iterative reconstruction-Veo (ASiR-V40%) algorithm. METHODS: This retrospective study included 86 patients who underwent low-dose CT for lung cancer screening. Images were reconstructed with ASiR-V40% and DLIR at low (DLIR-L), medium (DLIR-M), and high (DLIR-H) levels. CT value and standard deviation of lung tissue, erector spinae muscles, aorta, and fat were measured and compared across the four reconstructions. Subjective image quality was evaluated by two blind readers from three aspects: image noise, artifact, and visualization of small structures. RESULTS: The effective dose was 1.03 ± 0.36 mSv. There was no significant difference in CT values of erector spinae muscles and aorta, whereas the maximum difference for lung tissue and fat was less than 5 HU among the four reconstructions. Compared with ASiR-V40%, the DLIR-L, DLIR-M, and DLIR-H reconstructions reduced the noise in aorta by 11.44%, 33.03%, and 56.1%, respectively, and had significantly higher subjective quality scores in image artifacts (all p < 0.001). ASiR-V40%, DLIR-L, and DLIR-M had equivalent score in visualizing small structures (all p > 0.05), whereas DLIR-H had slightly lower score. CONCLUSIONS: Compared with ASiR-V40%, DLIR significantly reduces image noise in low-dose chest CT. DLIR strength is important and should be adjusted for different diagnostic needs in clinical application.

Clarifying winter clean heating importance: Insight chemical compositions and cytotoxicity exposure to primary and aged pollution emissions in China rural areas.

Residential solid fuel combustion (RSFC) is an important source of PM2.5. Here we investigate the cytotoxicity of primarily emitted and photochemically aged PM2.5 to A549 cells. Owing to the formation of water-soluble ions and organics (e.g., oPAHs and nPAHs), emission factors of PM2.5 were increased by 44.4% on average after 7-day equivalent photochemical aging, which greatly altered chemical profiles of freshly emitted PM2.5. Consequently, the cytotoxicity varied with aging duration that 2-day and 7-day aged PM2.5 induced 22.5% and 35.1%, respectively, higher levels of reactive oxygen species than primary emissions. Similar increases were also observed for multi-cytotoxicity. Correlation analysis and western blot results collectively confirmed HO-1/Nrf-2 signaling pathway dominated the cytotoxicity of aged PM2.5 from RSFC, which was regulated by the enhanced o-PAHs and n-PAHs during photochemical aging. Thus, aged and secondary aerosol exposure needs to be paid more attention due to the enhanced cytotoxicity and the vast crowd involved.

Self-Assembly of 2D Hybrid Double Perovskites on 3D Cs2 AgBiBr6 Crystals towards Ultrasensitive Detection of Weak Polarized Light.

We report the self-assembly of 2D double perovskite (BLA)2 CsAgBiBr7 (BLA=benzylammonium) on 3D Cs2 AgBiBr6 crystals, providing the first demonstration of polarization-sensitive photodetection using lead-free double perovskite heterocrystals (HCs). The (BLA)2 CsAgBiBr7 /Cs2 AgBiBr6 HC successfully combines the anisotropy of 2D double perovskites with the well-defined interface provided by heterogeneous integration. Driven by the built-in electric field in junction, photodetectors of HCs exhibit unique polarization dependence of zero-bias photocurrent with a large anisotropy ratio up to 9, which is 6 times amplified as compared to the pristine 2D (BLA)2 CsAgBiBr7 . More importantly, the present devices can remain polarization-sensitive with incident light intensity down to the nW cm-2 level. Our study on lead-free hybrid perovskite HCs marks a step toward establishing robust material foundations for fundamental scientific investigations and the development of optoelectronic devices.

Oxidative stress-inducing effects of various urban PM2.5 road dust on human lung epithelial cells among 10 Chinese megacities.

PM2.5 Road dust samples were collected from 10 representative cities in southern and northern China for examination of chemical components and oxidative stress levels in A549 cells. Downtown road dust was abundance of heavy metals, EC and PAHs compared to nondowntown road dust. Source apportionment also revealed the relative higher contribution of vehicle emission to downtown (35.8%) than nondowntown road dust (25.5%). Consequently, downtown road dust induced much higher intracellular reactive oxidative species (ROS) levels than that from nondowntown (p < 0.05). This study highlights that the ROS-inducing capacity of road dust in China is lower at lower latitudes, which resulted in a significantly higher ROS-inducing capacity of road dust from northern cities than southern ones. Hotspot analysis demonstrated that heavy metals (i.e., Cr, Zn, Cu and Pb) in road dust were the most closely associated with ROS production in A549 cells. Vehicle emission and combustion emission in road dust were identified to be correlated with cellular ROS production. The findings highlight the ROS-inducing effect of PM2.5 road dust and also serve as a reference to make the targeted solutions for urban road dust pollution control, especially from a public health perspective.

Effects of domestic solid fuel combustion emissions on the biomarkers of homemakers in rural areas of the Fenwei Plain, China.

BACKGROUND: The health effects of heavy solid fuel use in winter in rural China are of concern. The effects of air pollution resulting from domestic solid fuel combustion in rural households on rural homemakers' biomarkers were revealed in this study. METHODS: In total, 75 female homemakers from rural areas of Guanzhong Basin, the Fenwei Plain, People's Republic of China, were randomly selected and divided into three groups (biomass users, coal users, and nonusers of solid fuel user [control group]). The differences in biological indicators, including 8-hydrox-2'-deoxyguanosine (8-OHdG), interlukin-6 (IL-6), and tumor necrosis factor-alpha (TNF-α) in urine samples as well as blood pressure (BP, including systolic BP [SBP] and diastolic BP [DBP]) and heart rate (HR) among the groups in winter and summer were investigated using statistical analysis. RESULTS: IL-6, 8-OHdG, HR, SBP, and DBP were significantly higher in winter than in summer (P < 0.05) owing to the poor air quality resulted from the excessive use of solid fuels in winter. Significant seasonal differences in 8-OHdG were observed for both coal and biomass users. After the influence of confounders was removed, only IL-6 levels in the urine of solid fuel users were significantly higher than that of the control group. CONCLUSIONS: IL-6 is a sensitive biomarker representing inflammatory responses to particulate matter emitted through household solid fuel combustion. Locally, excessive use of solid fuels in winter posed serious PM2.5 pollution in this area and adverse effects on inflammatory biomarkers in these rural homemakers and induced DNA damage related to oxidative stress.

Cytotoxicity and Potential Pathway to Vascular Smooth Muscle Cells Induced by PM2.5 Emitted from Raw Coal Chunks and Clean Coal Combustion.

Coal combustion emits a large amount of PM2.5 (particulate matters with aerodynamic diameters less than 2.5 µm) and causes adverse damages to the cardiovascular system. In this study, emissions from anthracite and bitumite were examined. Red mud (RM) acts as an additive and is mixed in coal briquettes with a content of 0-10% as a single variable to demonstrate the reduction in the PM2.5 emissions. Burnt in a regulated combustion chamber, the 10% RM-containing bitumite and anthracite briquettes showed 52.3 and 18.6% reduction in PM2.5, respectively, compared with their chunk coals. Lower cytotoxicity (in terms of oxidative stresses and inflammation factors) was observed for PM2.5 emitted from the RM-containing briquettes than those from non-RM briquettes, especially for the bitumite groups. Besides, the results of western blotting illustrated that the inhibition of NF-κB and MAPK was the potential pathway for the reduction of cytokine levels by the RM addition. The regression analyses further demonstrated that the reduction was attributed to the lower emissions of transition metals (i.e., Mn) and PAHs (i.e., acenaphthene). This pilot study provides solid evidence for the cytotoxicity to vascular smooth muscle cells induced by PM2.5 from coal combustion and potential solutions for reducing the emission of toxic pollutants from human health perspectives.

Evaluation on exposures to particulate matter at a junior secondary school: a comprehensive study on health risks and effective inflammatory responses in Northwestern China.

Air pollutant measurement and respiratory inflammatory tests were conducted at a junior secondary school in Xi'an, Northwestern China. Hazardous substances including particulate matters (PMs), black carbon (BC) and particle-bounded polycyclic aromatic hydrocarbons (PAHs) were quantified both indoors and outdoors of the school. Source characterization with organic tracers and particle-size distribution demonstrated that the school's air was mostly polluted by combustion emissions from the surrounding environment. The evaluation of health assessment related to air quality was conducted by two methods, including potential risk estimation of air pollutants and direct respiratory inflammatory test. The incremental lifetime cancer risks associated with PAHs were estimated and were 1.62 × 10-6 and 2.34 × 10-6, respectively, for indoor and outdoor fine PMs. Both the values exceeded the threshold value of 1 × 10-6, demonstrating that the carcinogenic PAHs are a health threat to the students. Respiratory inflammatory responses of 50 students who studied in the sample classroom were examined with a fractional exhaled nitric oxide (FeNO) test, with the aid of health questionnaires. The average FeNO concentration was 17.4 ± 8.5 ppb, which was slightly lower than the recommended level of 20 ppb established by the American Thoracic Society for children. However, a wide distribution and 6% of the values were > 35 ppb, suggesting that the potentials were still high for eosinophilic inflammation and responsiveness to corticosteroids. A preliminary interpretation of the relationship between air toxins and respiratory inflammatory response demonstrated the high exposure cancer risks and inflammatory responses of the students to PMs in the city.

Particle size distribution and air pollution patterns in three urban environments in Xi'an, China.

Three urban environments, office, apartment and restaurant, were selected to investigate the indoor and outdoor air quality as an inter-comparison in which CO2, particulate matter (PM) concentration and particle size ranging were concerned. In this investigation, CO2 level in the apartment (623 ppm) was the highest among the indoor environments and indoor levels were always higher than outdoor levels. The PM10 (333 µg/m(3)), PM2.5 (213 µg/m(3)), PM1 (148 µg/m(3)) concentrations in the office were 10-50% higher than in the restaurant and apartment, and the three indoor PM10 levels all exceeded the China standard of 150 µg/m(3). Particles ranging from 0.3 to 0.4 µm, 0.4 to 0.5 µm and 0.5 to 0.65 µm make largest contribution to particle mass in indoor air, and fine particles number concentrations were much higher than outdoor levels. Outdoor air pollution is mainly affected by heavy traffic, while indoor air pollution has various sources. Particularly, office environment was mainly affected by outdoor sources like soil dust and traffic emission; apartment particles were mainly caused by human activities; restaurant indoor air quality was affected by multiple sources among which cooking-generated fine particles and the human steam are main factors.

Concentrations, particle-size distributions, and indoor/outdoor differences of polycyclic aromatic hydrocarbons (PAHs) in a middle school classroom in Xi'an, China.

Polycyclic aromatic hydrocarbons (PAHs) attached to particulate matter can affect respiratory health, especially the health of children, but information on the air quality in schools is generally lacking. This study investigated the PAH concentrations in a naturally ventilated classroom in Xi'an, China, from 16 to 31 May 2012. Particulate PAH concentrations were measured for samples collected on five-stage cascade impactors deployed inside the classroom and outside. PM2.5-bound PAH concentrations were 53.2 ng m(-3) indoors and 72.9 ng m(-3) outdoors. PAHs attached to very fine particles (VFPs) accounted for ~70% of the total PAHs. The PAH concentrations indoors were affected by the students' activities, cleaning, and smoking, while outdoors, the main sources were motor vehicle emissions and contaminated road dust. Particle-bound PAHs infiltrated the classroom through open windows, but the activities of the students and staff were also associated with an increase of PAHs attached to particles larger than 1.0 µm, most likely through resuspension. Cycles in the sources led to PAH concentrations 2-3 times higher on weekdays compared to weekends, both indoors and outdoors. PAH toxicity risks inside the classroom were substantially lower than those outdoors, and the highest risks were associated with VFPs.

A review on advancements in atmospheric microplastics research: The pivotal role of machine learning.

Microplastics (MPs), recognized as emerging pollutants, pose significant potential impacts on the environment and human health. The investigation into atmospheric MPs is nascent due to the absence of effective characterization methods, leaving their concentration, distribution, sources, and impacts on human health largely undefined with evidence still emerging. This review compiles the latest literature on the sources, distribution, environmental behaviors, and toxicological effects of atmospheric MPs. It delves into the methodologies for source identification, distribution patterns, and the contemporary approaches to assess the toxicological effects of atmospheric MPs. Significantly, this review emphasizes the role of Machine Learning (ML) and Artificial Intelligence (AI) technologies as novel and promising tools in enhancing the precision and depth of research into atmospheric MPs, including but not limited to the spatiotemporal dynamics, source apportionment, and potential health impacts of atmospheric MPs. The integration of these advanced technologies facilitates a more nuanced understanding of MPs' behavior and effects, marking a pivotal advancement in the field. This review aims to deliver an in-depth view of atmospheric MPs, enhancing knowledge and awareness of their environmental and human health impacts. It calls upon scholars to focus on the research of atmospheric MPs based on new technologies of ML and AI, improving the database as well as offering fresh perspectives on this critical issue.

Toxicity source apportionment of fugitive dust PM2.5-bound polycyclic aromatic hydrocarbons using multilayer perceptron neural network analysis in Guanzhong Plain urban agglomeration, China.

Polycyclic aromatic hydrocarbons (PAHs) in urban fugitive dust, known for their toxicity and ability to generate reactive oxygen species (ROS), are a major public health concern. This study assessed the spatial distribution and health risks of 15 PAHs in construction dust (CD) and road dust (RD) samples collected from June to November 2021 over the cities of Tongchuan (TC), Baoji (BJ), Xianyang (XY), and Xi'an (XA) in the Guanzhong Plain, China. The average concentration of ΣPAHs in RD was 39.5 ± 20.0 µg g-1, approximately twice as much as in CD. Four-ring PAHs from fossil fuels combustion accounted for the highest proportion of ΣPAHs in fugitive dust over all four cities. Health-related indicators including benzo(a)pyrene toxic equivalency factors (BAPTEQ), oxidative potential (OP), and incremental lifetime cancer risk (ILCR) all presented higher risk in RD than those in CD. The multilayer perceptron neural network algorithm quantified that vehicular and industrial emissions contributed 86 % and 61 % to RD and CD BAPTEQ, respectively. For OP, the sources of biomass and coal combustion were the key generator which accounted for 31-54 %. These findings provide scientific evidence for the direct efforts toward decreasing the health risks of fugitive dust in Guanzhong Plain urban agglomeration, China.

Assessing the Fit of N95 Filtering Facepiece Respirators Fitted with an Ear Loop Strap System: A Pilot Study.

Throughout the COVID-19 pandemic, hundreds of millions of people worldwide have become new users of respiratory protective devices. Facemasks and KN95 respirators utilizing an ear loop straps system (ELSS) have recently become popular among occupational and non-occupational populations. Part of this popularity is due to the ease of wearability as compared with traditional devices utilizing two headbands, one worn over the head and the other behind the neck-a universal strap system used in NIOSH-certified N95 filtering facepiece respirators (FFRs). Some users convert the two-strap configuration to an adjustable ELSS. The first objective of this pilot study was to quantitatively characterize how such a conversion impacts the respirator fit. Additionally, a novel faceseal (NFS) technology, which has been previously demonstrated to enhance the fit of N95 FFRs, was deployed to modify the ELSS-converted N95 FFRs. The second objective of this study was to quantify the fit improvement that results from adding the NFS to the ELSS. The study was conducted by performing the Occupational Safety and Health Administration (OSHA)-approved quantitative fit testing (QNFT) on 16 human subjects featuring different facial shapes and dimensions. Three models of cup-shaped N95 FFRs were tested in three versions: the standard version with manufacturer's strap system, the ELSS-converted, and the ELSS-converted version modified by adding the NFS. QNFT demonstrated that the fit of an N95 FFR featuring the traditional/standard headbands strap system is negatively impacted when this system is converted to an ELSS. The fit of an ELSS-converted respirator can be significantly improved by the addition of the NFS. We found that the FFR model and the strap system version are significant factors affecting the QNFT-determined respirator fit factor (FF), as well as the OSHA QNFT pass rate (FF ≥100). The findings suggest that the current NFS, if further improved, has a potential for developing a 'universally fitting' ELSS-equipped N95 FFR that can be used by the general public, the vast majority of whom do not have access to OSHA fit requirements.

Hysteresis response of groundwater depth on the influencing factors using an explainable learning model framework with Shapley values.

Machine learning has been widely used for groundwater prediction. However, the hysteresis response of groundwater depth (GD) to input features has not been fully investigated. This study uses an interpretation method to reveal the interplay between climate, human activity, and GD while considering the response of groundwater to multiple factors. Six factors [precipitation (P), wind speed (WS), temperature (T), population (POP), gross domestic product (GDP), and effective irrigated area (EIA)] were selected to analyze the hysteresis response of GD in terms of the lag correlation coefficient and lag time. The correlation between climatic variables and GD was weaker than that of anthropogenic variables. The lag time between variables and different types of GD was less than four months at most sites, except for EIA and WS in deep groundwater. The SVM model achieved satisfactory performance in 89 % of the sites. If there were sharp changes in GD during the testing period or significant variations in its seasonal patterns at different times, the SVM model performed poorly. The model was interpreted using the Shapley additive explanation method. The impact of POP and GDP on deep groundwater in irrigated areas was higher than that of shallow groundwater. In urban areas with intensive human activities, anthropogenic variables were the main factors affecting shallow groundwater while the impact of climate was gradually increasing in the suburbs. The influence of precipitation on shallow groundwater was decreased after water transfer from the South-to-North Water Diversion project. Furthermore, this study proposed a multifactor-driven conceptual model that can provide recommendations for analyzing groundwater dynamics in similar areas.

Near-infrared polarization-sensitive photodetection via interfacial symmetry engineering of an Si/MAPbI3 heterostructural single crystal.

Methylammonium lead iodide (MAPbI3) single crystals (SCs) have drawn particular attention in the optoelectronics field, due to their outstanding photoelectric performance. However, the structures of those MAPbI3 SCs are isotropic, which limits the further application of the materials for polarization-sensitive photodetection. Here, we propose a strategy of symmetry modulation by heterogeneously integrating large-sized MAPbI3 SCs with silicon (Si) wafers and we give the first demonstration of self-powered near-infrared (NIR) polarization-sensitive photodetection using MAPbI3 SCs. Created via a delicate solution method, the MAPbI3/Si heterostructures show a high crystalline quality and a solid interfacial connection. More importantly, the built-in electric field resulting from the band bending at the MAPbI3/Si heterostructure interface generates polar symmetry, which enables directional transport of photogenerated carriers, making the MAPbI3/Si heterostructures highly polarization-sensitive. Consequently, in the self-powered mode, NIR photodetectors of MAPbI3/Si heterostructures exhibit large polarization ratios of 3.3 at 785 nm and 2.8 at 940 nm. Moreover, a high detectivity of 7.35 × 1012 Jones of the present devices is also achieved. Our work gives the first demonstration of self-powered polarization-sensitive photodetection of MAPbI3 SCs and provides a strategy to design polarization-sensitive materials beyond the conventional limitations induced by isotropic structures.

Effects of indoor air purification intervention on blood pressure, blood­oxygen saturation, and heart rate variability: A double-blinded cross-over randomized controlled trial of healthy young adults.

The use of indoor air purifier (IAP) has received growing attention as a mitigation strategy for reducing indoor air pollution, but the evidence on their cardiovascular benefits is unclear. This study aims to evaluate whether the use of IAP can reduce the adverse effects of indoor particulate matter (PM) on cardiovascular health among young healthy population. A randomized, double-blind, cross-over, IAP intervention of 38 college students was conducted. The participants were assigned into two groups to receive the true and sham IAPs for 36 h in random order. Systolic and diastolic blood pressure (SBP; DBP), blood oxygen saturation (SpO2), heart rate variability (HRV) and indoor size-fractioned particulate matter (PM) were real-time monitored throughout the intervention. We found that IAP could reduce indoor PM by 41.7-50.5 %. Using IAP was significantly associated with a reduction of 2.96 mmHg (95 % CI: -5.71, -0.20) in SBP. Increased PM was significantly associated with increased SBP (e.g., 2.17 mmHg [0.53, 3.81], 1.73 mmHg [0.32, 3.14] and 1.51 mmHg [0.28, 2.75] for an IQR increment of PM1 [16.7 µg/m3], PM2.5 [20.6 µg/m3] and PM10 [37.9 µg/m3] at lag 0-2 h, respectively) and decreased SpO2 (-0.44 % [-0.57, -0.29], -0.41 % [-0.53, -0.30] and - 0.40 % [-0.51, -0.30] for PM1, PM2.5 and PM10 at lag 0-1 h, respectively), which could last for about 2 h. Using IAPs could halve indoor PM levels, even in relatively low air pollution settings. The exposure-response relationships suggested that the benefits of IAPs on BP may only be observed when indoor PM exposure is reduced to a certain level.