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Circulating tumor cells (CTCs) are important markers for cancer. The part of tumor cells that are detached from the primary tumor or metastatic tumor and enter the blood circulation is called CTCs. It is crucial to develop a rapid, accurate, and easy-to-implement diagnostic system for CTCs for early tumor diagnosis and for monitoring progression of the disease. In this work, we reported a colorimetric and fluorescent dual-mode assay for the detection of CTCs. Our assay used magnetic nanoparticles and aptamer for CTCs capture and gold nanoparticles-loaded covalent organic frameworks (Au@COFs) for signal amplification, respectively. The magnetic nanoparticles were modified with folic acid to capture CTCs by interaction between folic acid and the folate receptor overexpressed on the surface of tumor cells. The covalent organic frameworks were engineered to have both nitro-reductase-like and glucose–oxidase-like activities. The nitro-reductase-like activity converted the substrate p-nitrophenol to p-nitroaniline for colorimetric detection, and the glucose-oxidase-like activity enabled fluorescence detection. Specifically, Au@COFs catalyzed glucose oxidation and generated hydrogen peroxide to oxidize Fe2+to Fe3+, which converted MIL(Al)-MOF to MIL(Fe)-MOF through ion exchange, resulting in the fluorescence quenching of MIL(Al)-MOF. Our assay showed high sensitivity with a detection limit of 17 cells/mL using MCF-7 cells as model cancer cells. This work provided an efficient and ultrasensitive strategy for CTCs detection and has potential applications in cancer identification and diagnosis. Dual-mode detection system, combining colorimetric and fluorescent signals, integration of magnetic nanoparticles and aptamers for CTC capture, and utilization of covalent organic frameworks loaded with gold nanoparticles for signal amplification can improve sensitivity and accuracy.

In this study, the flexural and longitudinal shear performances of two types of precast lightweight steel–ultra-high performance concrete (UHPC) composite beams are investigated, where a cluster UHPC slab (CUS) and a normal UHPC slab (NUS) are connected to a steel beam using headed studs through discontinuous shear pockets and full-length shear pockets, respectively. Results show that the longitudinal shear force of the CUS is greater than that of the NUS, whereas the interfacial slip of the former is smaller. Owing to its better integrity, the CUS exhibits greater flexural stiffness and a higher ultimate bearing capacity than the NUS. To further optimize the design parameters of the CUS, a parametric study is conducted to investigate their effects on the flexural and longitudinal shear performances. The square shear pocket is shown to be more applicable for the CUS, as the optimal spacing between two shear pockets is 650 mm. Moreover, a design method for transverse reinforcement is proposed; the transverse reinforcement is used to withstand the splitting force caused by studs in the shear pocket and prevent the UHPC slab from cracking. According to calculation results, the transverse reinforcement can be canceled when the compressive strength of UHPC is 150 MPa and the volume fraction of steel fiber exceeds 2.0%.

Activation of biomass burning aerosols (BBA) and fossil fuel combustion aerosols (FFA) in fogs and clouds significantly impact regional air quality through aqueous chemistry and climate by affecting cloud microphysics. However, we lack direct observations of how these aerosols behave in fogs and clouds. Using a newly developed aerosol‐cloud sampling system, we conducted observations during fog events and found that BBA, despite their high organic content, effectively contributed to super‐micron interstitial aerosols and fog droplets in low supersaturation fogs. In contrast, FFA, predominantly externally mixed organic, did not grow beyond the super‐micron size in fogs due to their near‐hydrophobic nature. Measurements conducted under supersaturations relevant for cloud formation revealed that portions of FFA could serve as cloud condensation nuclei, but only when supersaturation exceeded ∼0.14%. These findings have broad implications for future investigations into the influence of BBA and FFA on fog and cloud chemistry and their interactions with clouds. Tiny particles, known as aerosols, emitted from combustion of biomass and fossil fuels, can impact air quality and global climate by interacting with fog and clouds. However, we lack direct observational evidence of how these aerosols behave in these conditions. In our study, we developed an advanced aerosol‐cloud sampling system to observe aerosol activation during fog events. Our findings highlight a crucial factor of aerosol activation: the mixing of these aerosols. Biomass burning aerosols with an internal mixture of organic and inorganic components activate more easily, even in conditions with low supersaturation like fog. In contrast, fossil fuel combustion aerosols are often externally mixed and almost water‐repellent, requiring higher supersaturation to become cloud condensation nuclei. Understanding these distinctions has significant implications for regional air quality and the intricate interactions between aerosols and clouds. By gaining insights into how various aerosols interact with fog and clouds, we can enhance our understanding of their impact on our environment and climate. Advanced Aerosol‐Cloud sampling system was developed to characterize aerosol activation in fogsBiomass burning aerosols efficiently form fog droplets, while fossil fuel combustion aerosols are almost hydrophobic and don't contributeFossil fuel combustion organic aerosols can serve as CCN in high supersaturation conditions (>0.14%) Advanced Aerosol‐Cloud sampling system was developed to characterize aerosol activation in fogs Biomass burning aerosols efficiently form fog droplets, while fossil fuel combustion aerosols are almost hydrophobic and don't contribute Fossil fuel combustion organic aerosols can serve as CCN in high supersaturation conditions (>0.14%)

The commercial continuous‐flow streamwise thermal‐gradient cloud condensation nuclei (CCN) counter is widely used in aerosol CCN activity measurements which are critical for investigating aerosol‐cloud interactions. In CCN measurements, a critical threshold is needed for distinguishing interstitial aerosols and activated droplets, and a default threshold of 0.75 μm was set in CCN counter. Theoretically, interstitial aerosols could also grow larger than 0.75 μm in CCN counter at low supersaturations, thus theoretical thresholds derived from the Köhler theory were suggested. Here, we report that droplet growth in the CCN counter is kinetically limited and CCN‐active droplets does not reach their theoretical diameters under low supersaturations. Neglecting the kinetic growth limitation in CCN identification would count less CCN and underestimate the aerosol hygroscopicity parameter κ$\kappa $by up to 50% for supersaturations lower than 0.1%. We recommend that thresholds considering kinetic limitations should be used as new criteria for CCN identification under low supersaturations. Accurate Cloud Condensation Nuclei (CCN) predictions in climate and regional models are crucial for the assessment of climate effects of aerosol‐cloud interactions. Direct measurements of CCN activity, varied by aerosol size, hygroscopicity, and supersaturation, are important for model verifications and improvements. The commercial continuous‐flow streamwise thermal‐gradient CCN counter (CCNC) is widely used in CCN activity measurements. We found that the droplet growth in the CCNC is kinetically limited under low supersaturations (<0.14%), thus not reaching the theoretical critical activation diameter, which significantly affect CCN identification. Kinetic model results revealed that the wet diameter thresholds of CCN identification that took the kinetic limitations of droplet growth into account were independent of dry aerosol size and hygroscopicity thus could be directly used as new criteria for CCN identification. Neglecting the kinetic growth limitation in CCN identification would result in significant bias in CCN activity measurements and thus supersaturated aerosol hygroscopicity retrievals. Findings of this research have significant impacts on CCN activity measurements and supersaturated aerosol hygroscopicity investigations. Limited hygroscopic growth of cloud condensation nuclei (CCN) in CCN counter is recognized and evaluated based on model analysisKinetic limitations in CCN counter impacts significantly on size‐resolved CCN activity measurementsKinetic limitations in CCN counter impacts significantly on aerosol hygroscopicity measurements under low supersaturation Limited hygroscopic growth of cloud condensation nuclei (CCN) in CCN counter is recognized and evaluated based on model analysis Kinetic limitations in CCN counter impacts significantly on size‐resolved CCN activity measurements Kinetic limitations in CCN counter impacts significantly on aerosol hygroscopicity measurements under low supersaturation

The effect of extracts from four types of tea made from Camelia sinensis(green, white, black, and oolong) on in vitroamylolysis of gelatinized starch and the underlying mechanisms were studied. Of the four extracts, black tea extract (BTE) gave the strongest inhibition of starch digestion and on α-amylase activity. Fluorescence quenching and surface plasmon resonance (SPR) showed compounds in BTE bound to α-amylase more strongly than those in the green, white, and oolong tea extracts. Individual testing of five phenolic compounds abundant in tea extracts showed that theaflavins had a greater inhibitory effect than catechins on α-amylase. SPR showed that theaflavins had much lower equilibrium dissociation constants and therefore bound more tightly to α-amylase than catechins. We conclude that BTE had a stronger inhibitory effect on in vitroenzymatic starch digestion than the other tea extracts, mainly due to the higher content of theaflavins causing stronger inhibition of α-amylase.