Search

Ammonia (NH3) volatilization from agricultural lands is a main source of atmospheric reduced nitrogen species (NHx). Accurately quantifying its contribution to regional atmospheric NHxdeposition is critical for controlling regional air nitrogen pollution. The stable nitrogen isotope composition (expressed by δ15N) is a promising indicator to trace atmospheric NHxsources, presupposing a reliable nitrogen isotopic signature of NH3emission sources. To obtain more specific seasonal δ15N values of soil NH3volatilization for reliable regional seasonal NH3source partitioning, we utilized an active dynamic sampling technique to measure the δ15N-NH3values volatilized from maize cropping land in northeast China. These values varied from −38.0 to −0.2‰, with a significantly lower rate-weighted value observed in the early period (May–June, −30.5 ± 6.7‰) as compared with the late period (July–October, −8.5 ± 4.3‰). Seasonal δ15N-NH3variations were related to the main NH3production pathway, degree of soil ammonium consumption, and soil environment. Bayesian isotope mixing model analysis revealed that without considering the seasonal δ15N variation in soil-volatilized NH3could result in an overestimate by up to absolute 38% for agricultural volatile NH3to regional atmospheric bulk ammonium deposition during July–October, further demonstrating that it is essential to distinguish seasonal δ15N profile of agricultural volatile NH3in regional source apportionment.

This letter presents a low-cost ultrathin metal-only transmitarray (MOTA) antenna based on polarization rotation elements at X-Band. The unit-cell comprises only dual metal layers etched with a pair of perpendicularly orientated fan-shaped slits and separated by an air gap of 2 mm, featuring an ultrathin configuration of 0.067λ at 10 GHz. It twists the polarization of transmission wave orthogonally with regard to the incidence. By tuning the length of fan-shaped slits along with mirroring the bottom layer of the unit-cell, a 360° phase span and a high transmission magnitude are realized. To validate the design concept, an ultrathin MOTA accommodating 361 elements is fabricated and measured. In terms of testing results, 7% 1 dB gain bandwidth and 42% peak aperture efficiency are realized. Moreover, the sidelobe level and cross-polarization level are 22 and 25 dB at 10 GHz, respectively. In comparison with existing MOTAs, the proposed design features a remarkably lower profile with reduced fabrication complexity and cost while preserving a desirable overall performance. Furthermore, the proposed ultrathin unit-cell can also be adopted in a metal-only folded transmitarray for an even thinner and compact structure.

IMPORTANCE: Progression of myopia in a school-aged population due to home confinement (January to May 2021) during the COVID-19 pandemic has been previously reported. A key remaining question was whether the myopia spike in children aged 6 to 8 years persisted. OBJECTIVE: To investigate the changes in refractive status and prevalence of myopia in school-aged children 1 year after home confinement ended in China. DESIGN, SETTING, AND PARTICIPANTS: This cross-sectional study with a cohort substudy prospectively evaluated data from school-based photoscreening in Feicheng, China. Children aged 6 to 13 years participated in 8 screenings from 2015 to 2021. EXPOSURES: Noncycloplegic photorefraction was conducted using the Spot Vision photoscreener. MAIN OUTCOMES AND MEASURES: The main outcomes were the differences in spherical equivalent refraction (SER) and prevalence of myopia between 2020 (during home confinement) and 2021 (after home confinement). The SER was recorded for each child, and the prevalence of myopia was calculated annually for each age group. RESULTS: A total of 325 443 children participated in the study (51.4% boys, 48.6% girls; age range, 6 to 13 years). Compared with 2020, the mean SER of children in 2021 increased significantly for those aged 6 (0.42 diopters [D]), 7 (0.41 D), and 8 (0.33 D) years. The prevalence of myopia in 2021 was similar to in 2019 for each age group (aged 6 years: 7.9% vs 5.7%; aged 7 years: 13.9% vs 13.6%; aged 8 years: 29.5% vs 26.2%). Both the prevalence of myopia and mean SER for these children returned to their prepandemic levels. CONCLUSIONS AND RELEVANCE: Compared with 2020, the prevalence of myopia among children aged 6 to 8 years in the 2021 screenings decreased, and the mean SER returned to prepandemic level. The refractive development in children aged 6 to 8 years may be most susceptible to environmental changes. These findings support the premise that age 6 to 8 years is a critical period for myopia development and suggest a need to focus preventive interventions for myopia control on children in this age range.

Concrete-filled steel tube (CFST) arch bridges have a high center of gravity and a substantial mass, resulting in a discernible seismic response. Consequently, long-span CFST arch bridges must retain exceptional seismic performance and appropriate seismic control design. In this study, the dynamic response and seismic performance of a unique swallow-type CFST arch bridge when subjected to longitudinal earthquake forces were analyzed using numerical simulation methods. The displacement and axial force response results and their laws of the key bridge components were obtained. Taking into account seismic checking calculations, two damping measures were proposed for the CFST arch bridge, as the relative displacement of the girder end exceeded the allowable value specified. The appropriate design parameters for viscous dampers and lead shear dampers were examined. Additionally, the seismic performance of these dampers was verified through a shaking table test using a 1:16 scale model. The findings indicated that when subjected to Wenchuan Wolong wave action, the relative displacement between the steel box girder and the concrete girder of the bridge was significantly larger, leading to girder end pounding. The limit values were surpassed by 32.5% and 50%, when subjected to the uniform and traveling wave excitations, respectively, thus indicating that the expansion joint was the most vulnerable component. Following the selection of optimal parameters for the dampers, the dampers exhibited the capability to mitigate seismic and pounding impacts. Long-span CFST arch bridges with dampers were found to effectively reduce the seismic response of the skewback strain and vault, as well as the relative displacement of the girder ends. Furthermore, the average maximum damping rates achieved by the viscous damper and the lead shear damper reached 44.9% and 44.6%, respectively.

The presence of organic pollutants in drinking water is an environmental problem threatening public health. Water purifiers are commonly recognized as effective purification equipment for drinking water and are thus prevalent in the market, so there is a need to assess their true effects on drinking water. In this study, we have analyzed the distribution, potential sources, and health risks of phthalate esters (PAEs) in tap as well as purified water. 7 out of 22 target PAEs have been detected in a total of 75 drinking water samples, including tap water (TW), water vending machines (WVMs), and water boiling machines (WBMs). The total concentrations of 22 PAEs are N.D. to 447 ng L−1in TW samples, 25.7 to 1.10 × 103ng L−1in WBM water, and N.D. to 841 ng L−1in WVM water. The concentrations of PAEs in most WVM and WBM samples were comparable or slightly higher than those in TW samples. Meanwhile, the ΣPAE concentrations in the nearshore of the Yangtze Estuary area (northern and southern areas) were slightly higher than those from offshore areas (Pudong: PD, Fengxian and Minhang: FM), which may be attributed to the source water. Combining the results of principal component analysis and correlation analysis, certain PAEs, e.g., diisobutyl phthalate (DIBP), dibuthyl phthalate (DBP), and di(2-ethylhexyl) phthalate (DEHP), were more polluting than diethyl phthalate (DEP) and di-methyl phthalate (DMP) in WVM water than those in TW samples. This work suggests that the application of water purifiers may not remove certain PAEs efficiently from drinking water. In addition, the estimated daily intakes (EDIs) of ΣPAE viadrinking water from automatic water purifiers were 2–3 times those from tap water under a high-exposure scenario, but all EDIs are well below current health regulatory guidelines for PAEs. This survey indicates that water purifiers made nearly no decrease to the PAE concentrations and possibly have negative effects on the quality of drinking water.

IMPORTANCE: Time spent in outdoor activities has decreased owing to home confinement for the coronavirus disease 2019 (COVID-19) pandemic. Concerns have been raised about whether home confinement may have worsened the burden of myopia owing to substantially decreased time spent outdoors and increased screen time at home. OBJECTIVE: To investigate the refractive changes and prevalence of myopia in school-aged children during the COVID-19 home confinement. DESIGN, SETTING, AND PARTICIPANTS: A prospective cross-sectional study using school-based photoscreenings in 123 535 children aged 6 to 13 years from 10 elementary schools in Feicheng, China, was conducted. The study was performed during 6 consecutive years (2015-2020). Data were analyzed in July 2020. EXPOSURES: Noncycloplegic photorefraction was examined using a photoscreener device. MAIN OUTCOMES AND MEASURES: The spherical equivalent refraction was recorded for each child and the prevalence of myopia for each age group during each year was calculated. The mean spherical equivalent refraction and prevalence of myopia were compared between 2020 (after home confinement) and the previous 5 years for each age group. RESULTS: Of the 123 535 children included in the study, 64 335 (52.1%) were boys. A total of 194 904 test results (389 808 eyes) were included in the analysis. A substantial myopic shift (approximately −0.3 diopters [D]) was found in the 2020 school-based photoscreenings compared with previous years (2015-2019) for younger children aged 6 (−0.32 D), 7 (−0.28 D), and 8 (−0.29 D) years. The prevalence of myopia in the 2020 photoscreenings was higher than the highest prevalence of myopia within 2015-2019 for children aged 6 (21.5% vs 5.7%), 7 (26.2% vs 16.2%), and 8 (37.2% vs 27.7%) years. The differences in spherical equivalent refraction and the prevalence of myopia between 2020 and previous years were minimal in children aged 9 to 13 years. CONCLUSIONS AND RELEVANCE: Home confinement during the COVID-19 pandemic appeared to be associated with a significant myopic shift for children aged 6 to 8 years according to 2020 school-based photoscreenings. However, numerous limitations warrant caution in the interpretation of these associations, including use of noncycloplegic refractions and lack of orthokeratology history or ocular biometry data. Younger children’s refractive status may be more sensitive to environmental changes than older ages, given the younger children are in a critical period for the development of myopia.

According to the investigation of library resources discovery system construction in 20 universities in China, the aggregation discovery service provided by the multi-source aggregation function, the discovery function is based on aggregation and the comprehensive revealing function. This article evaluates user usage and acceptance based on refinements of the functions mentioned above. The investigation shows that compared with the diversity of function, users are more concerned about the practicability, the intuition and the academy. Thus, systems should choose the best sources and pay attention to the metadata normalization, and enhance the correlation to standard datasets.

The earth has abundant water resources, and efficient harvesting of energy from waves is always a research hotspot. In this paper, we fabricate a box-like triboelectric-electromagnetic hybrid nanogenerator for harvesting water wave energy, which is composed of the triboelectric nanogenerator (TENG) and the electromagnetic generator (EMG). In the case of TENG, the contact and separation between the aluminum film-coated PMMA cylinder and the silicone film covered interdigitated Ag electrodes is formed by ocean waves. In the case of EMG, a rolling magnetic ball is placed on the four coils to generate magnetic flux changes, thus generating electricity. Several experiments are conducted to validate the availability. Experimental results show that the instantaneous maximum output power of TENG is 0.08 mW at a load of 100 MΩ, and the instantaneous maximum output power of EMG is 14.9 mW at a load of 1 kΩ. The hybrid nanogenerator can light up 60 LEDs at the same time. After storing energy in the capacitor, the output DC signal can provide a continuous energy supply with the temperature sensor. More important, the nanogenerator can power the wireless acoustic sensing system.

Sepsis is a common clinical critical disease with high mortality. The excessive release of cytokines from macrophages is the main cause of out-of-control immune response in sepsis. Mesenchymal stem cells (MSCs) are thought to be useful in adjunctive therapy of sepsis and related diseases, due to their function in immune regulation, anti-inflammatory, antibacterial, and tissue regeneration. Also there have been several successful cases in clinical treatment. Some previous studies have shown that MSCs regulate the function of macrophages through secreting cytokines and extracellular vesicles, or transferring mitochondria directly to target cells, which affects the progress of sepsis. Here, we review the regulation of MSCs on macrophages in sepsis, mainly focus on the regulation ways. We hope that will help to understand the immunological mechanism and also provide some clues for the clinical application of MSCs in the biotherapy of sepsis.

Although the MAPK pathway is aberrantly activated in triple-negative breast cancers (TNBCs), the clinical outcome of MEK-targeted therapy is still poor. Through a genome-wide CRISPR-Cas9 library screening, we find that inhibition of PSMG2 sensitizes TNBC cells BT549 and MB468 to the MEK inhibitor AZD6244. Mechanistically, PSMG2 knockdown impairs proteasome function, which in turn activates autophagy-mediated PDPK1 degradation. The PDPK1 degradation significantly enhances AZD6244-induced tumor cell growth inhibition by interrupting the negative feedback signals toward the AKT pathway. Consistently, co-targeting proteasomes and MEK with inhibitors synergistically suppresses tumor cell growth. The autophagy inhibitor chloroquine partially relieves the PDPK1 degradation and reverses the growth inhibition induced by combinatorial inhibition of MEK and proteasome. The combination regimen with the proteasome inhibitor MG132 plus AZD6244 synergistically inhibits tumor growth in a 4T1 xenograft mouse model. In summary, our study not only unravels the mechanism of MEK inhibitor resistance but also provides a combinatorial therapeutic strategy for TNBC in clinics.

Photodynamic therapy (PDT) offers an alternative for cancer treatment by using ultraviolet or visible light in the presence of a photosensitizer and molecular oxygen, which can produce highly reactive oxygen species that ultimately leading to the ablation of tumor cells by multifactorial mechanisms. However, this technique is limited by the penetration depth of incident light, the hypoxic environment of solid tumors, and the vulnerability of photobleaching reduces the efficiency of many imaging agents. In this work, we reported a cellular level dual-functional imaging and PDT nanosystem BMEPC-loaded DNA origami for photodynamic therapy with high efficiency and stable photoreactive property. The carbazole derivative BMEPC is a one- and two-photon imaging agent and photosensitizer with large two-photon absorption cross section, which can be fully excited by near-infrared light, and is also capable of destroying targets under anaerobic condition by generating reactive intermediates of Type I photodynamic reactions. However, the application of BMEPC was restricted by its poor solubility in aqueous environment and its aggregation caused quenching. We observed BMEPC-loaded DNA origami effectively reduced the photobleaching of BMEPC within cells. Upon binding to DNA origami, the intramolecular rotation of BMEPC became proper restricted, which intensify fluorescence emission and radicals production when being excited. After the BMEPC-loaded DNA origami are taken up by tumor cells, upon irradiation, BMEPC could generate free radicals and be released due to DNA photocleavage as well as the following partially degradation. Apoptosis was then induced by the generation of free radicals. This functional nanosystem provides an insight into the design of photosensitizer-loaded DNA origami for effective intracellular imaging and photodynamic therapy.

Many chemotherapeutics used for cancer treatments encounter issues during delivery to tumors in vivoand may have high levels of systemic toxicity due to their nonspecific distribution. Various materials have been explored to fabricate nanoparticles as drug carriers to improve delivery efficiency. However, most of these materials suffer from multiple drawbacks, such as limited biocompatibility and inability to engineer spatially addressable surfaces that can be utilized for multifunctional activity. Here, we demonstrate that DNA origami possessed enhanced tumor passive targeting and long-lasting properties at the tumor region. Particularly, the triangle-shaped DNA origami exhibits optimal tumor passive targeting accumulation. The delivery of the known anticancer drug doxorubicin into tumors by self-assembled DNA origami nanostructures was performed, and this approach showed prominent therapeutic efficacy in vivo. The DNA origami carriers were prepared through the self-assembly of M13mp18 phage DNA and hundreds of complementary DNA helper strands; the doxorubicin was subsequently noncovalently intercalated into these nanostructures. After conducting fluorescence imaging and safety evaluation, the doxorubicin-containing DNA origami exhibited remarkable antitumor efficacy without observable systemic toxicity in nude mice bearing orthotopic breast tumors labeled with green fluorescent protein. Our results demonstrated the potential of DNA origami nanostructures as innovative platforms for the efficient and safe drug delivery of cancer therapeutics in vivo.

We herein report a novel fluorescent probe for Hg2+based on the deprotection of 1,3-dithiolane, viathe covalent assembly principle. Presence of Hg2+triggers a cascade, which ultimately furnishes the push–pull backbone of a fluorescent dye, rendering a turn-on signal from a zero background and hence high detection sensitivity.

A general feature in the diurnal cycle of atmospheric ammonia (NH3) concentrations is a morning spike that typically occurs around 07:00 to 10:00 (LST). Current hypotheses to explain this morning’s NH3increase remain elusive, and there is still no consensus whether traffic emissions are among the major sources of urban NH3. Here, we confirmed that the NH3morning pulse in urban Beijing is a universal feature, with an annual occurrence frequency of 73.0% and a rapid growth rate (>20%) in winter. The stable nitrogen isotopic composition of NH3(δ15N–NH3) in winter also exhibited a significant diurnal variation with an obvious morning peak at 07:00 to 10:00 (−18.6‰, mass-weighted mean), higher than other times of the day (−26.3‰). This diurnal pattern suggests that a large fraction of NH3in the morning originated from nonagricultural sources, for example, power plants, vehicles, and coal combustion that tend to have higher δ15N–NH3emission signatures relative to agricultural emissions. In particular, the contribution from vehicular emissions increased from 18% (00:00 to 07:00) to 40% (07:00 to 10:00), while the contribution of fertilizer sources to NH3was reduced from 15.8% at 00:00 to 07:00 to 5.2% at 07:00 to 10:00. We concluded that NH3concentrations in winter mornings in urban Beijing were indeed enhanced by vehicle emissions, which should be considered in air pollution regulations.

Fiber-shaped solar cells (FSCs) have attracted increasing interest in recent years due to their numerous advantages. Herein we report the first prototype of highly flexible all-solid-state single-wire FSCs by using CuInSe2(CIS) as the model photoactive semiconductor. CIS layer is electrodeposited on a flexible Mo wire as the substrate. Subsequently, CdS, ZnO and ITO layers are orderly deposited on the Mo/CIS wire, and each upper layer ensures full contact with the underlying layer, resulting in an excellent structural uniformity along circumference of the FSC. This Mo/CIS/CdS/ZnO/ITO single-wire FSC exhibits a power conversion efficiency of 2.31%, which is one of the highest values in all reported FSCs. More importantly, the present all-solid-state single-wire FSC exhibits stable conversion efficiency (2.16–2.32%) during rotation (0∼360°), bending (0∼360°) and long-time aging (stored at 60°C for 600h) processes, which makes it possible to fabricate very long single-wire FSC with stable efficiency for weaving large-area devices and/or the stereoscopic cell textiles. Our method provides a new and general approach for fabricating flexible single-wire FSC with various kinds of photovoltaic semiconductor materials, and it also would be applicable to develop other flexible electronic circuits.

Ionic Polymer-Metal Composite (IPMC) is a new electro-active polymer, which has the advantages of light weight, flexi- bility, and large stroke with low driving voltage. Because of these features, IPMC can be applied to bionic robotic actuators, artificial muscles, as well as dynamic sensors. However, IPMC has the major drawback of low generative blocking force. In this paper, in order to enhance the blocking force, the Nafion membranes with thickness of 0.22 mm, 0.32 mm, 0.42 mm, 0.64 mm and 0.8 mm were prepared by casting from liquid solution. By employing these Nafion membranes, IPMCs with varying thickness were fabricated by electroless plating. The elastic modulus of the casted Nafion membranes were obtained by a nano-indenter, and the current, the displacement and the blocking force were respectively measured by the apparatus for ac- tuation test. Finally, the effects of the thickness on the performance of IPMC were analyzed with an electromechanical model. Experimental study and theory analysis indicate that as the thickness increases, the elastic modulus of Nafion membrane and the blocking force of IPMC increase, however, the current and the displacement decrease.

Abstract: The distribution of borehole temperature at four high-altitude alpine glaciers was investigated. The result shows that the temperature ranges from −13.4°C to −1.84°C, indicating the glaciers are cold throughout the boreholes. The negative gradient (i.e., the temperature decreasing with the increasing of depth) due to the advection of ice and climate warming, and the negative gradient moving downwards relates to climate warming, are probably responsible for the observed minimum temperature moving to lower depth in boreholes of the Gyabrag glacier and Miaoergou glacier compared to the previously investigated continental ice core borehole temperature in West China. The borehole temperature at 10 m depth ranges from −8.0°C in the Gyabrag glacier in the central Himalayas to −12.9°C in the Tsabagarav glacier in the Altai range. The borehole temperature at 10 m depth is 3∼4 degrees higher than the calculated mean annual air temperature on the surface of the glaciers and the higher 10 m depth temperature is mainly caused by the production of latent heat due to melt-water percolation and refreezing. The basal temperature is far below the melting point, indicating that the glaciers are frozen to bedrock. The very low temperature gradients near the bedrock suggest that the influence of geothermal flux and ice flow on basal temperature is very weak. The low temperature and small velocity of ice flow of glaciers are beneficial for preservation of the chemical and isotopic information in ice cores.

Measuring the nitrogen isotope compositions (δ15N) of nitric oxide (NO) from different sources helps to quantify the relative contributions of atmospheric NOx. Soil is one of the most important sources of atmospheric NOx, but only limited measurements on the δ15N of soil‐emitted NO exist, hampering our ability to partition sources to air pollution. Here we conducted soil incubations to measure the δ15N‐NO under defined aerobic or anaerobic conditions, favoring either nitrification or denitrification. Soils were collected from seven sites spanning three ecosystems in northern China (two agricultural, two forest, and three grassland sites). We found that the δ15N‐NO and their associated N isotope fractionations were significantly different between anaerobic and aerobic conditions in seven soils. Under aerobic condition, the δ15N‐NO ranged from −62‰ to −50‰ (averaged −56 ± 4‰), being significantly more negative (by 23‰) than those under anaerobic condition (−45‰ to −23‰, averaged −33 ± 7‰). The apparent N isotope fractionation for NO production under aerobic condition (15εaerobic= 61 ± 3‰) was significantly higher (by 26‰) than under anaerobic condition (15εanaerobic= 35 ± 6‰), with a small variability among ecosystem types. Our study demonstrates that the δ15N‐NO from different soils are very different from fuel combustions (mainly from 0‰ to +20‰), supporting that measuring 15N is a useful tool to partition the contributions of soil NO to atmospheric NOx. Our results also imply δ15N‐NO produced by nitrification and denitrification distinctly different, as these two processes are dominant processes producing NO under aerobic and anaerobic conditions, respectively. Nitric oxide (NO) affects the atmosphere chemistry and NO itself a key component of air pollution and a precursor to other air pollutants like particulate matter and ozone. To reduce the air pollution, it is crucial to identify the atmospheric NO sources. Measuring 15N natural abundance has been considered as a promising tool to identify different sources, but the measurement on δ15N for soil‐emitted NO is limited, adding to the large uncertainties on NO partitioning. Here we measured the δ15N‐NO emitted from three ecosystem types across seven sites (two agriculture, two forest, and three grassland sites) under defined anaerobic or aerobic conditions. We found that soil‐emitted NO was 15N‐depleted (−62‰ to −23‰) related to the source from fossil fuel combustion (0–20‰), suggesting that δ15N can be used to separate these two sources. We also found that the δ15N‐NO under aerobic condition (nitrification prevailing, −62‰ to −50‰) was much lower than under anaerobic condition (denitrification prevailing, −45‰ to −23‰), which provide a useful tool to better understand the relative contributions of different sources of NO. In sum, soil‐emitted NO has their own different isotope fingerprint, depending on the soil oxygen conditions, and can be used to partition sources. The δ15N‐NO from soil (−62‰ to −23‰) is different from fuel combustion (0‰ to 20‰), allowing effective source partitionThe δ15N‐NO produced under aerobic condition (favor nitrification) was more negative than under anaerobic condition (favor denitrification)The 15εfor NO production under aerobic condition (61 ± 3‰) was significantly higher than under anaerobic condition (35 ± 6‰)

This research was conducted with the aim of developing an energy-efficient, noiseless, movable bionic eye for use in bionic toys. This novel bionic eye is actuated by an ionic polymer-metal composite actuator. The overall size of the eye was 39 mm in length, 45 mm in width, and 45 mm in thickness. The experimental results revealed such a bionic eye design is feasible. This type of bionic eye is appropriate for use in toys and robots to increase their visual impact.