Bioinspired Proton Pump on Ferroelectric HfO2-Coupled Ir Catalysts with Bidirectional Hydrogen Spillover for pH-Universal and Superior Hydrogen Production.

The improvement of hydrogen evolution reaction kinetics can be largely accelerated by introducing a well-designed hydrogen spillover pathway into the catalysts. However, the driving force and mechanism of hydrogen migration on the surface of catalysts are poorly understood and are rarely explored in depth. Here, inspired by the specific ferroelectric property of HfO2, Mn-O-Ca sites in Mn4CaO5, and Fe-Fe sites in hydrogenases, we constructed a bioinspired HfO2 coupled with Ir catalysts (Ir/HfO2@C) with an alkaline hydrogen reverse spillover effect from HfO2 to interface and acid hydrogen spillover effect from Ir to interface. Benefiting from the bidirectional hydrogen spillover pathways controlled by pH, Ir/HfO2@C displays a narrow overpotential difference between acidic and alkaline electrolytes. Remarkably, Ir/HfO2@C shows a remarkable mass current density and turnover frequency value, far exceeding the benchmark Ir/C by 20.6 times. More importantly, this Ir/HfO2@C achieves extraordinarily low overpotentials of 146 and 39 mV at 10 mV cm-2 in seawater and alkaline seawater, respectively. The anion-exchange membrane water electrolyzer equipped with Ir/HfO2@C as a cathode exhibits excellent and stable H2-evolution performance on 2.22 V at 1.0 A cm-2. We expect that the bioinspired strategy will provide a new concept for designing catalytic materials for efficient and pH-universal electrochemical hydrogen production.

2D Nano-Channeled Molybdenum Compounds for Accelerating Interfacial Polysulfides Catalysis in Li-S Battery.

The shuttle effect, which causes the loss of active sulfur, passivation of lithium anode, and leads to severe capacity attenuation, is currently the main bottleneck for lithium-sulfur batteries. Recent studies have disclosed that molybdenum compounds possess exceptional advantages as a polar substrate to immobilize and catalyze lithium polysulfide such as high conductivity and strong sulfiphilicity. However, these materials show incomplete contact with sulfur/polysulfides, which causes uneven redox conversion of sulfur and results in poor rate performance. Herein, a new type of 2D nano-channeled molybdenum compounds (2D-MoNx) via the 2D organic-polyoxometalate superstructure for accelerating interfacial polysulfide catalysis toward high-performance lithium-sulfur batteries is reported. The 2D-MoNx shows well-interlinked nano-channels, which increase the reactive interface and contact surface with polysulfides. Therefore, the battery equipped with 2D-MoNx displays a high discharge capacity of 912.7 mAh g-1 at 1 C and the highest capacity retention of 523.7 mAh g-1 after 300 cycles. Even at the rate of 2 C, the capacity retention can be maintained at 526.6 mAh g-1 after 300 cycles. This innovative nano-channel and interfacial design of 2D-MoNx provides new nanostructures to optimize the sulfur redox chemistry and eliminate the shuttle effect of polysulfides.

Closed-Loop Control of Macrophage Engineering Enabled by Focused-Ultrasound Responsive Mechanoluminescence Nanoplatform for Precise Cancer Immunotherapy.

Macrophage engineering has emerged as a promising approach for modulating the anti-tumor immune response in cancer therapy. However, the spatiotemporal control and real-time feedback of macrophage regulatory process is still challenging, leading to off-targeting effect and delayed efficacy monitoring therefore raising risk of immune overactivation and serious side effects. Herein, a focused ultrasound responsive immunomodulator-loaded optical nanoplatform (FUSION) is designed to achieve spatiotemporal control and status reporting of macrophage engineering in vivo. Under the stimulation of focused ultrasound (FUS), the immune agonist encapsulated in FUSION can be released to induce selective macrophage M1 phenotype differentiation at tumor site and the near-infrared mechanoluminescence of FUSION is generated simultaneously to indicate the initiation of immune activation. Meanwhile, the persistent luminescence of FUSION is enhanced due to hydroxyl radical generation in the pro-inflammatory M1 macrophages, which can report the effectiveness of macrophage regulation. Then, macrophages labeled with FUSION as a living immunotherapeutic agent (FUSION-M) are utilized for tumor targeting and focused ultrasound activated, immune cell-based cancer therapy. By combining the on-demand activation and feedback to form a closed loop, the nanoplatform in this work holds promise in advancing the controllability of macrophage engineering and cancer immunotherapy for precision medicine.

Nanomaterials-Enabled Physicochemical Antibacterial Therapeutics: Toward the Antibiotic-Free Disinfections.

Bacterial infection continues to be an increasing global health problem with the most widely accepted treatment paradigms restricted to antibiotics. However, the overuse and misuse of antibiotics have triggered multidrug resistance of bacteria, frustrating therapeutic outcomes, and leading to higher mortality rates. Even worse, the tendency of bacteria to form biofilms on living and nonliving surfaces further increases the difficulty in confronting bacteria because the extracellular matrix can act as a robust barrier to prevent the penetration of antibiotics and resist environmental damage. As a result, the inability to eliminate bacteria and biofilms often leads to persistent infection, implant failure, and device damage. Therefore, it is of paramount importance to develop alternative antimicrobial agents while avoiding the generation of bacterial resistance to prevent the large-scale growth of bacterial resistance. In recent years, nano-antibacterial materials have played a vital role in the antibacterial field because of their excellent physical and chemical properties. This review focuses on new physicochemical antibacterial strategies and versatile antibacterial nanomaterials, especially the mechanism and types of 2D antibacterial nanomaterials. In addition, this advanced review provides guidance on the development direction of antibiotic-free disinfections in the antibacterial field in the future.

IrPd Nanoalloy-Structured Bifunctional Electrocatalyst for Efficient and pH-Universal Water Splitting.

The lack of high efficiency and pH-universal bifunctional electrocatalysts for water splitting to hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) hinders the large-scale production of green hydrogen. Here, an IrPd electrocatalyst supported on ketjenblack that exhibits outstanding bifunctional performance for both HER and OER at wide pH conditions is presented. The optimized IrPd catalyst exhibits a specific activity of 4.46 and 3.98 A mgIr -1 in the overpotential of 100 and 370 mV for HER and OER, respectively, in alkaline conditions. When applied to the anion exchange membrane electrolyzer, the Ir44 Pd56 /KB catalyst shows a stability of >20 h at a current of 250 mA cm-2 for water decomposition, indicating promising prospects for practical applications. Beyond offering an advanced electrocatalyst, this work also guides the rational design of desirable bifunctional electrocatalysts for HER and OER by regulating the microenvironments and electronic structures of metal catalytic sites for diverse catalysis.

Evaluation of a Gaussian dispersion transformation technique for tomographic mapping of the concentration field of atmospheric chemicals using multi-path optical remote sensing.

Horizontal radial plume mapping is a cost-effective optical remote sensing method for sensitive mapping concentration distribution of atmospheric chemicals in real time. However, its sparse sampling poses challenges for reconstruction algorithms. Neither non-smooth nor smooth algorithms can recover the realistic plume shape. A new approach called Gaussian dispersion transformation (GDT) has been proposed. It first reconstructs the emission rates from unknown sources. Then concentrations are calculated through a transformation matrix defined by a Gaussian dispersion model. Smoothness regularization is also applied during the reconstruction. The method was evaluated by using randomly generated maps. It shows significant improvement over a reconstructed plume shape. The nearness shows 72%-117% better than the non-negative least-square (NNLS) algorithm and 15%-26% better than the low third derivative (LTD) algorithm. A controlled-release field experiment of methane was also conducted. The realistic concentration distribution was calculated by using a Lagrangian stochastic dispersion model. The GDT algorithm successfully recovered the realistic plume shape. The nearness shows approximately 16% better than the NNLS and the LTD algorithms. Finally, a sensitivity analysis shows that the wind direction and atmospheric stability are the main parameters that affect the performance of the GDT algorithm.

Sharper photonic nanojets generated by microspheres under higher-order radially polarized beam illumination.

Photonic nanojets (PNJs) generated from a single microsphere illuminated by higher-order radially polarized (RP) beams are investigated. The effects of the size parameters of higher-order RP beams, the refractive index, and radius of the dielectric microsphere on the full width at half-maximum and peak intensity of the PNJ are numerically discussed and qualitatively interpreted. The results show that the minimal width of the PNJ can be obtained by optimally adjusting the size parameter. The PNJ beam waist becomes gradually narrower with increasing the radial mode number. As compared to the case of plane wave illumination, sharper PNJs are more easily generated when irradiated by a higher-order RP beam, even for microspheres with lower refractive indices or larger radii. Our findings can promote potential applications of PNJs in a variety of fields including super-resolution microscopy, nanolithography, and optical data storage.

Directional control of the off-normal scattering from a single nanodisk by superposed linearly and radially polarized beams.

A scheme to dynamically control the off-axis directional scattering from a silicon nanodisk is proposed, which is based on focused fields formed by the coherent superposition of radially and linearly polarized beams. When the phase condition of the generalized Kerker conditions is satisfied at a specified wavelength, the amplitude requirement for the off-axis directional scattering along a required direction can be fulfilled by tuning the magnitude ratio of the two focused beams. Therefore, directional control of the off-axis scattering in the meridional plane is achieved without the manipulation of the working wavelength. Our findings provide new possibilities of future potential applications of all-dielectric nanoantennas.

Optimization of a volatile organic compound control strategy in an oil industry center in Canada by evaluating ozone and secondary organic aerosol formation potential.

Volatile organic compounds (VOCs) play a vital role in the formation of photochemical smog and haze in large urban environments. Previous source apportionment studies have focused on the contribution of different sources to VOC concentration with a view to pinpointing the major culprits for effective emission mitigation. However, different VOC sources may have different ozone (O3) and secondary organic aerosol (SOA) formation potentials. From a control perspective, it would be more rational to consider the role of individual VOC sources in secondary pollution; therefore, here, we propose a tiered source identification method that considers the formation potentials of O3 and SOA, which we applied in Calgary, Alberta, a site under the influence of multiple competing VOC sources. The pollution characteristics, secondary pollutant formation potential, and geographical origin of VOC sources were investigated over a five-year period. Seven major sources were identified using the positive matrix factorization (PMF) model, among which vehicle exhausts and solid fuel combustion were the dominant VOC sources responsible for O3 (60%) and SOA (63%) formation. Combustion of both liquid fuel (gasoline and diesel) and solid fuel (wood and coal) has exceeded the contribution of oil and gas production and become the top contributor to O3 and aerosol pollution in Calgary. This finding is consistent with the significant reduction (32.2-99.8%) in oil and gas production in Calgary over the period of 2013-2017. The source apportionment results show that the primary VOC source has shifted from conventional oil and gas extraction to a mixture of vehicle exhausts and oil and gas extraction, indicating the effectiveness of emission control measures taken in the energy sectors. Moreover, regionally transported VOCs from combustion sources in southeastern British Columbia have greatly increased the VOC level and secondary pollutant formation in Calgary. To effectively alleviate secondary pollution problems, the performance of joint pollution control measures has been suggested by the governments of both Alberta and British Columbia. These findings reveal that the tiered source identification strategy combining the traditional receptor model with socioeconomic factors, emission inventory, and source region analysis is a robust and promising tool for the interpretation of source apportionment results and optimization of secondary pollution control.

Identification of Early Salinity Stress-Responsive Proteins in Dunaliella salina by isobaric tags for relative and absolute quantitation (iTRAQ)-Based Quantitative Proteomic Analysis.

Salt stress is one of the most serious abiotic factors that inhibit plant growth. Dunaliella salina has been recognized as a model organism for stress response research due to its high capacity to tolerate extreme salt stress. A proteomic approach based on isobaric tags for relative and absolute quantitation (iTRAQ) was used to analyze the proteome of D. salina during early response to salt stress and identify the differentially abundant proteins (DAPs). A total of 141 DAPs were identified in salt-treated samples, including 75 upregulated and 66 downregulated DAPs after 3 and 24 h of salt stress. DAPs were annotated and classified into gene ontology functional groups. The Kyoto Encyclopedia of Genes and Genomes pathway analysis linked DAPs to tricarboxylic acid cycle, photosynthesis and oxidative phosphorylation. Using search tool for the retrieval of interacting genes (STRING) software, regulatory protein⁻protein interaction (PPI) networks of the DAPs containing 33 and 52 nodes were built at each time point, which showed that photosynthesis and ATP synthesis were crucial for the modulation of early salinity-responsive pathways. The corresponding transcript levels of five DAPs were quantified by quantitative real-time polymerase chain reaction (qRT-PCR). These results presented an overview of the systematic molecular response to salt stress. This study revealed a complex regulatory mechanism of early salt tolerance in D. salina and potentially contributes to developing strategies to improve stress resilience.

SDC-DeepLabv3+: Lightweight and Precise Localization Algorithm for Safflower-Harvesting Robots.

Harvesting robots had difficulty extracting filament phenotypes for small, numerous filaments, heavy cross-obscuration, and similar phenotypic characteristics with organs. Robots experience difficulty in localizing under near-colored backgrounds and fuzzy contour features. It cannot accurately harvest filaments for robots. Therefore, a method for detecting and locating filament picking points based on an improved DeepLabv3+ algorithm is proposed in this study. A lightweight network structure, ShuffletNetV2, was used to replace the backbone network Xception of the traditional DeepLabv3+. Convolutional branches for 3 different sampling rates were added to extract information on the safflower features under the receptive field. Convolutional block attention was incorporated into feature extraction at the coding and decoding layers to solve the interference problem of the near-color background in the feature-fusion process. Then, using the region of interest of the safflower branch obtained by the improved DeepLabv3+, an algorithm for filament picking-point localization was designed based on barycenter projection. The tests demonstrated that this method was capable of accurately localizing the filament. The mean pixel accuracy and mean intersection over union of the improved DeepLabv3+ were 95.84% and 96.87%, respectively. The detection rate and weights file size required were superior to those of other algorithms. In the localization test, the depth-measurement distance between the depth camera and target safflower filament was 450 to 510 mm, which minimized the visual-localization error. The average localization and picking success rates were 92.50% and 90.83%, respectively. The results show that the proposed localization method offers a viable approach for accurate harvesting localization.

A bone-targeting near-infrared luminescence nanocarrier facilitates alpha-ketoglutarate efficacy enhancement for osteoporosis therapy.

Osteoporosis (OP), which largely increases the risk of fractures, is the most common chronic degenerative orthopedic disease in the elderly due to the imbalance of bone homeostasis. Alpha-ketoglutaric acid (AKG), an endogenous metabolic intermediate involved in osteogenesis, plays critical roles in osteogenic differentiation and mineralization and the inhibition of osteoclastogenic differentiation. However, the low bioavailability and poor bone-targeting efficiency of AKG seriously limit its efficacy in OP treatment. In this work, a bone-targeting, near-infrared emissive lanthanide luminescence nanocarrier loaded with AKG (ß-NaYF4:7%Yb, 60%Nd@NaLuF4@mSiO2-EDTA-AKG, abbreviated as LMEK) is developed for the enhancement of AKG efficacy in OP therapy. By utilizing the NIR-II luminescence (>1000 nm) of LMEK, whole-body bone imaging with high spatial resolution is achieved to confirm the bone enrichment of AKG noninvasively in vivo. The results reveal that LMEK exhibits a remarkable OP therapeutic effect in improving the osseointegration of the surrounding bone in the ovariectomized OP mice models, which is validated by the enhanced inhibition of osteoclast through hypoxia-inducible factor-1α suppression and promotion of osteogenic differentiation in osteoblast. Notably, the dose of AKG in LMEK can be reduced to only 0.2 % of the dose when pure AKG is used in therapy, which dramatically improves the bioavailability of AKG and mitigates the metabolism burden. This work provides a strategy to conquer the low utilization of AKG in OP therapy, which not only overcomes the challenges in AKG efficacy for OP treatment but also offers insights into the development and application of other potential drugs for skeletal diseases. STATEMENT OF SIGNIFICANCE: Alpha-ketoglutarate (AKG) is an intermediate within the Krebs cycle, participating in diverse metabolic and cellular processes, showing potential for osteoporosis (OP) therapy. However, AKG's limited bioavailability and inefficient bone-targeting hinder its effectiveness in treating OP. Herein, a near-infrared emissive nanocarrier is developed that precisely targets bones and delivers AKG, bolstering its effectiveness in OP therapy. Thanks to this efficient bone-targeting delivery, the AKG dosage is reduced to 0.2 % of the conventional treatment level. This marks the first utilization of a bone-targeting nanocarrier to amplify AKG's bioavailability and OP therapy efficacy. Furthermore, the mechanism of AKG-loaded nanocarrier regulating the biological behavior of osteoclasts and osteoblasts mediated is tentatively explored.

Bacteriophage-like Nanobiocatalysts with Spiky Topography and Dual-Atom Sites for Treating Drug-Resistant Bacteria.

Overuse of antibiotics leads to the proliferation of drug-resistant bacterial strains, worsening global morbidity, and mortality rates. Bioinspired nanomaterials present a promising avenue for developing nonantibiotic strategies against drug-resistant bacteria. Here, we engineer a bacteriophage-inspired artificial nanobiocatalyst via nonstoichiometric W18O49 that features a spiky topography and synergistic dual-atom sites for combating drug-resistant bacterial infection. Benefiting from the strong interaction within the synergistic Fe-O-Mo sites, the synthesized spiky artificial nanobiocatalyst exhibits superior reactive oxygen species (ROS)-catalytic activity, attributed to the regulated adsorption affinity between the reaction intermediates and catalytic sites. The experimental and theoretical investigations demonstrate that the bioinspired biocatalyst can effectively capture and kill bacteria through its spiky morphology and potent ROS-catalytic activity, which can enable a significant reduction in bacterial viability through downregulating genes associated with biosynthesis, cellular maintenance, and respiration. In vivo experiments demonstrate that the spiky artificial biocatalyst accelerates the reconstruction of drug-resistant bacteria-infected skin wounds in rabbits, exhibiting efficacy comparable to that of vancomycin. It is expected that this bioinspired study on spiky artificial nanobiocatalysts offers a straightforward path to facilitate the development of both bionic and nonantibiotic disinfection strategies.

Synergistic enhancement of Ni2P anode for high lithium/sodium storage by N, P, S triply-doping and soft template-assisted strategy.

Transition metal phosphides have demonstrated excellent performance in the field of energy conversion and storage, where nickel phosphide is one of the most prominent type of phosphides. However, achieving long cycle life with higher specific capacity in the case of Ni2P is still a great challenge. In this study, the composition and structure of Ni2P composites are rationally and precisely adjusted by heteroatoms doping and micelle-assisted methods to attain high capacity for longer cycles at high rate. Among all studied combinations, nickel phosphide particles anchored to triple heteroatom (N, P, S) doped carbon network skeleton (Ni2P@NPS) exhibited specific capacities of 727.3, 586.6, and 321.5 mA h g-1 after 1000 cycles at 1, 2 and 6 A g-1 for lithium-ion batteries (LIBs) and 230.1 mA h g-1 at 1 A g-1 for sodium-ion batteries (SIBs) after 560 cycles. The introduction of heteroatoms optimized the electronic structure of the electrode materials and promoted mass and charge transfer, while triple-heteroatom doped carbon substrates and uniformly dispersed spherical structures formed an active three-dimensional conductive network structure that provided a stronger driving force and richer channels for Li+/Na+ transport. Theoretical calculations showed that the high content of pyrrole nitrogen as well as the additional sulfur ensured improved electrical conductivity and enhanced ion adsorption performance. This study encourages further research into the synergistic effect of N, P, S co-doping materials for improving Li+/Na+ storage and the exploration of other heteroatom co-doping systems.

An NIR-IIb emissive transmembrane voltage nano-indicator for the optical monitoring of electrophysiological activities in vivo.

In vivo transmembrane-voltage detection reflected the electrophysiological activities of the biological system, which is crucial for the diagnosis of neuronal disease. Traditional implanted electrodes can only monitor limited regions and induce relatively large tissue damage. Despite emerging monitoring methods based on optical imaging have access to signal recording in a larger area, the recording wavelength of less than 1000 nm seriously weakens the detection depth and resolution in vivo. Herein, a Förster resonance energy transfer (FRET)-based nano-indicator, NaYbF4:Er@NaYF4@Cy7.5@DPPC (Cy7.5-ErNP) with emission in the near-infrared IIb biological window (NIR-IIb, 1500-1700 nm) is developed for transmembrane-voltage detection. Cy7.5 dye is found to be voltage-sensitive and is employed as the energy donor for the energy transfer to the lanthanide nanoparticle, NaYbF4:Er@NaYF4 (ErNP), which works as the acceptor to achieve electrophysiological signal responsive NIR-IIb luminescence. Benefiting from the high penetration and low scattering of NIR-IIb luminescence, the Cy7.5-ErNP enables both the visualization of action potential in vitro and monitoring of Mesial Temporal lobe epilepsy (mTLE) disease in vivo. This work presents a concept for leveraging the lanthanide luminescent nanoprobes to visualize electrophysiological activity in vivo, which facilitates the development of an optical nano-indicator for the diagnosis of neurological disorders.

Lanthanide luminescence nanothermometer with working wavelength beyond 1500 nm for cerebrovascular temperature imaging in vivo.

Nanothermometers enable the detection of temperature changes at the microscopic scale, which is crucial for elucidating biological mechanisms and guiding treatment strategies. However, temperature monitoring of micron-scale structures in vivo using luminescent nanothermometers remains challenging, primarily due to the severe scattering effect of biological tissue that compromises the imaging resolution. Herein, a lanthanide luminescence nanothermometer with a working wavelength beyond 1500 nm is developed to achieve high-resolution temperature imaging in vivo. The energy transfer between lanthanide ions (Er3+ and Yb3+) and H2O molecules, called the environment quenching assisted downshifting process, is utilized to establish temperature-sensitive emissions at 1550 and 980 nm. Using an optimized thin active shell doped with Yb3+ ions, the nanothermometer's thermal sensitivity and the 1550 nm emission intensity are enhanced by modulating the environment quenching assisted downshifting process. Consequently, minimally invasive temperature imaging of the cerebrovascular system in mice with an imaging resolution of nearly 200 µm is achieved using the nanothermometer. This work points to a method for high-resolution temperature imaging of micron-level structures in vivo, potentially giving insights into research in temperature sensing, disease diagnosis, and treatment development.

Global observational coverage of onshore oil and gas methane sources with TROPOMI.

Satellite observations have been used to measure methane (CH4) emissions from the oil and gas (O&G) industry, particularly by revealing previously undocumented, very large emission events and basin-level emission estimates. However, most satellite systems use passive remote sensing to retrieve CH4 mixing ratios, which is sensitive to sunlight, earth surface properties, and atmospheric conditions. Accordingly, the reliability of satellites for routine CH4 emissions monitoring varies across the globe. To better understand the potentials and limitations of routine monitoring of CH4 emissions with satellites, we investigated the global observational coverage of the TROPOMI instrument onboard the Sentinel-5P satellite-the only satellite system currently with daily global coverage. A 0.1° × 0.1° gridded global map that indicates the average number of days with valid observations from TROPOMI for 2019-2021 was generated by following the measurement retrieval quality-assurance threshold (≥ 0.5). We found TROPOMI had promising observational coverage over dryland regions (maximum: 58.6%) but limited coverage over tropical regions and high latitudes (minimum: 0%). Cloud cover and solar zenith angle were the primary factors affecting observational coverage at high latitudes, while aerosol optical thickness was the primary factor over dryland regions. To further assess the country-level reliability of satellites for detecting and quantifying CH4 emissions from the onshore O&G sector, we extracted the average annual TROPOMI observational coverage (TOC) over onshore O&G infrastructure for 160 countries. Seven of the top-10 O&G-producing countries had an average annual TOC < 10% (< 36 days per year), which indicates the limited ability to routinely identify large emissions events, track their duration, and quantify emissions rates using inverse modelling. We further assessed the potential performance of the latter by combining TOC and the uncertainties from the global O&G inventory. Results indicate that the accuracy of emissions quantifications of onshore O&G sources using TROPOMI data and inverse modeling will be higher in countries located in dryland and mid-latitude regions and lower in tropical and high-latitude regions. Therefore, current passive-sensing satellites have low potential for frequent monitoring of large methane emissions from O&G sectors in countries located in tropical and high latitudes (e.g., Canada, Russia, Brazil, Norway, and Venezuela). Alternative methods should be considered for routine emissions monitoring in these regions.

Observation of black carbon in Northern China in winter of 2018-2020 and its implications for black carbon mitigation.

Enhanced observations of BC in hotspot regions with a high temporal resolution are critical to refining our BC mitigation strategies, which are co-directed by air-quality and climate goals. In this work, the temporal variation and emission sources of BC in Shijiazhuang, Northern China, during the winter of 2018-2020 were investigated on the basis of multi-wavelength Aethalometer BC observations. The average BC concentrations decreased from 9.13 ± 6.63 µg/m3 in the winter of 2018 to 3.51 ± 2.48 µg/m3 in the winter of 2020. The BC source attributions derived from the Aethalometer model showed that the BC concentrations in Shijiazhuang in the winter of 2018 were mainly contributed by biomass burning (53 %). In contrast, during the winter of 2019 and 2020, fossil fuel combustion (BCff) exhibited higher contributions, and higher BC concentrations attributed to greater BCff contributions. Potential source contribution function (PSCF) analysis suggested that local emissions in Shijiazhuang and transport from highly industrialized regions like central Shanxi and southern Hebei contributed significantly to BC in Shijiazhuang. Concentration weighted trajectory (CWT) analysis revealed that the BC contributions from source regions decreased successively from the winter of 2018 to the winter of 2020. Our results also implied an air quality/climate co-benefit effect of enforcing multi-scale air-quality improvement regulations. Yet, it is still worth noting that some of the measures in favor of reducing BC emissions contradict the measures for reducing CO2. The synergies of BC to air quality and climate should be considered and addressed by policymakers with the aim of realizing a sustainable environment.

Amorphization-Modulated Metal Sulfides with Boosted Active Sites and Kinetics for Efficient Enzymatic Colorimetric Biodetection.

Colorimetric biosensing has become a popular sensing method for the portable detection of a variety of biomarkers. Artificial biocatalysts can replace traditional natural enzymes in the fields of enzymatic colorimetric biodetection; however, the exploration of new biocatalysts with efficient, stable, and specific biosensing reactions has remained challenging so far. Here, to enhance the active sites and overcome the sluggish kinetics of metal sulfides, the creation of an amorphous RuS2 (a-RuS2 ) biocatalytic system is reported, which can dramatically boost the peroxidase-mimetic activity of RuS2 for the enzymatic detection of diverse biomolecules. Due to the existence of abundant accessible active sites and mildly surface oxidation, the a-RuS2 biocatalyst displays a twofold Vmax value and much higher reaction kinetics/turnover number (1.63 × 10-2 s-1 ) compared to that of the crystallized RuS2 . Noticeably, the a-RuS2 -based biosensor shows an extremely low detection limit of H2 O2 (3.25 × 10-6 m), l-cysteine (3.39 × 10-6 m), and glucose (9.84 × 10-6 m), respectively, thus showing superior detection sensitivity to many currently reported peroxidase-mimetic nanomaterials. This work offers a new path to create highly sensitive and specific colorimetric biosensors in detecting biomolecules and also provides valuable insights for engineering robust enzyme-like biocatalysts via amorphization-modulated design.

On-road mileage-based emission factors of gaseous pollutants from bi-fuel taxi fleets in China: The influence of fuel type, vehicle speed, and accumulated mileage.

Urban taxis tend to be high mileage vehicles, and therefore potentially a significant contributor to local air pollution. To investigate the on-road emissions of gaseous air pollutants from urban taxi fleets, the mileage-based emission factors (EFs) for 20 gasoline/CNG bi-fuel taxis in China were measured using the in situ monitoring system. It was found that shifting the taxis' fuel from gasoline to CNG could cause significant emissions reduction in CO, slight drop in HC and small increase in NOx. With the fuel shift from China-VI gasoline to GB 18047-2017 CNG, approximately 82% reduction in CO, 14% reduction in HC and about 14% more NOx was observed. With fuel shift from China-III gasoline to GB 18047-2000 CNG, the reductions were 65%, 6% and 11%, respectively. When the China-VI gasoline-fueled taxis travel at higher speed (60 km/h or higher), the vehicles emit approxiamtly ten times more CO than that at lower speed (20-50 km/h). The mileage-based NOxEFs was strongly and positively related to the vehicles' speed for the taxis fueled by China-VI gasoline and GB 18047-2017 CNG. The ratio of NOx and HC emissions from gasoline-fueled taxis is lower than that from CNG-fueled taxis. Considerable reductions of the mileage-based EFs of CO, HC, and NOx from China-VI gasoline- and GB 18047-2017 CNG-fueled bi-fuel taxis were recorded. The taxi vehicles with higher accumulated mileage (greater than 200,000 km) were found with higher CO and HC emissions, due to the deterioration of vehicle engine performance and the exhaust catalyst system.