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The neutral form drag coefficient is an important parameter when estimating surface turbulent fluxes over Arctic sea ice. The form drag caused by surface features ( $C_{\text {dn},\text {fr}}$ ) dominates the total drag in the winter, but long-term pan-Arctic records of $C_{\text {dn},\text {fr}}$ are still lacking for Arctic sea ice. In this study, we first developed an improved surface feature detection algorithm and characterized the surface features (including height and spacing) over Arctic sea ice during the late winter of 2009–2019 using the full-scan laser altimeter data obtained in the Operation IceBridge mission. $C_{\text {dn},\text {fr}}$ was then estimated using an existing parameterization scheme. This was followed by applying a satellite-derived backscatter coefficient ( ${\sigma }_{\text {vv}}^{o}$ ) to $C_{\text {dn},\text {fr}}$ regression model to extrapolate, for the first time, $C_{\text {dn},\text {fr}}$ to the pan-Arctic scale for the entire winter season over two decades (from 1999 to 2021). We found that the surface features have a larger height and smaller spacing over multiyear ice (1.15 ± 0.21 and 142 ± 49 m) than over first-year ice (0.90 ± 0.16 and 241 ± 129 m). The monthly mean $C_{\text {dn},\text {fr}}$ increases through the winter from $0.2\times 10^{-3}$ in November to 0.4– $0.5\times 10^{-3}$ in April. The central Arctic has the largest $C_{\text {dn},\text {fr}}$ (up to $2\times 10^{-3}$ ) but experienced a drop of ~50% in the period from 2001/2002 to 2008/2009. The interannual fluctuations in $C_{\text {dn},\text {fr}}$ are strongly linked to the variability of sea ice thickness and deformation, and the latter has become increasingly important for $C_{\text {dn},\text {fr}}$ since 2009.

Photo-induced cancer therapies, mainly including photothermal therapy (PTT) and photodynamic therapy (PDT), have attracted numerous attentions owing to the high selectivity, convenience, and few side effects. However, single PTT usually requires high laser power density, and single PDT usually needs a high photosensitizer dosage. Herein, a kind of composite nanocarrier based on clay (laponite)–polypyrrole (LP) nanodisks was synthesized via the in situ polymerization of pyrrole in the interlayer space of laponite. LP composite nanodisks were then coated with polyvinylpyrrolidone (PVP) to form the LP–PVP (LPP) composite nanodisks which show an excellent colloidal stability and in vitro and in vivo biocompatibility. The interlayer space of LPP can be further used for the loading of Chlorin e6 (Ce6), with an ultrahigh loading capacity of about 89.2%. Furthermore, the LPP nanocarrier can enhance the PDT effect of Ce6 under the irradiation of a 660 nm laser, through enhancing its solubility and cellular uptake amount. Besides, it was found that LPP nanodisks exhibit a more outstanding photothermal performance under a 980 nm near-infrared laser (NIR) than a 808 nm NIR laser, with the photothermal conversion efficiency of 45.7 and 27.7%, respectively. The in vitro and in vivo tumor therapy results evidently confirm that the Ce6-loaded LPP nanodisks have a combined tumor PTT and PDT effect, which can significantly suppress the tumor malignant proliferation.

The combination of reactive oxygen species (ROS)-induced chemodynamic therapy (CDT) and photothermal therapy (PTT) holds a promising application prospect for their superb anticancer efficiency. Herein, we created a novel Fe3O4@polydopamine (PDA)@bovine serum albumin (BSA)-Bi2S3composite as a theranostic agent, by chemically linking the Fe3O4@PDA with BSA-Bi2S3via the amidation between the carboxyl groups of BSA and the amino groups of PDA. In this formulation, the Fe3O4NPs could not only work as a mimetic peroxidase to trigger Fenton reactions of the innate H2O2in the tumor and generate highly cytotoxic hydroxyl radicals (•OH) to induce tumor apoptosis but also serve as the magnetic resonance imaging (MRI) contrast agent to afford the precise cancer diagnosis. Meanwhile, the PDA could prevent the oxidization of Fe3O4, thus supporting the long-term Fenton reactions and the tumor apoptosis in the tumor. The Bi2S3component exhibits excellent photothermal transducing performance and computed tomography (CT) imaging capacity. In addition, the PDA and Bi2S3endow the Fe3O4@PDA@BSA-Bi2S3composite with an excellent photothermal transforming ability which could lead to tumor hyperthermia. All of these merits play the synergism with the tumor microenvironment and qualify the Fe3O4@PDA@BSA-Bi2S3NPs for a competent agent in the MRI/CT-monitored enhanced PTT/CDT synergistic therapy. Findings in this research will evoke new interests in future cancer therapeutic strategies based on biocompatible nanomaterials.

A hybrid silica monolith containing vinyl groups was synthesized by a sol–gel method, and then ground and treated, yielding silica particles with a 3–5 μm particle size and a 10–20 nm pore size. Cellulose derivatives containing 3,5-dimethylphenylcarbamate groups and methacrylate groups regioselectively were then immobilized onto the surface of the above particles by the thiol–ene click reaction using an alkanedithiol as the crosslinking agent, thus forming a solvent-resisting crosslinked network structure attached onto the surface of the particles. The immobilization degree was more than 80%, and the back pressure of the chiral stationary phase (CSP) packed column was relatively low and was maintained at around 3.0 MPa. The as-prepared CSPs were shown to be able to effectively separate various enantiomers with different mobile phases.

ABSTRACTIn China, both inactivated hepatitis A (HA) vaccine and live attenuated HA vaccine are available. We conducted a trial to evaluate 5-year immune persistence induced by one dose of inactivated or live attenuated HA vaccines in children. Subjects with no HA vaccination history had randomly received one dose of inactivated or live attenuated HA vaccine at 18–60 months of age. Anti-HAV antibody concentrations were measured before vaccination and at the first, second, and fifth year after vaccination. Suspected cases of hepatitis A were monitored during the study period. A total of 332 subjects were enrolled and 182 provided evaluable serum samples at all planned time points. seropositive rate at 5 y was 85.9% in the inactivated HA vaccine group and 90.7% in the live attenuated HA vaccine group. GMCs were 76.3% mIU/ml (95% CI: 61.7 – 94.4) and 66.8mIU/ml (95% CI: 57.8 – 77.3), respectively. No significant difference in antibody persistence between 2 groups was found. No clinical hepatitis A case was reported. A single dose of an inactivated or live attenuated HA vaccine at 18–60 months of age resulted in high HAV seropositive rate and anti-HAV antibody concentrations that lasted for at least 5 y.

The North Water Polynya (NOW) is the largest recurrent Arctic coastal polynya. The formation of the NOW is critically dependent on the development of an ice arch that defines its northern boundary. In this study, high‐resolution ENVISAT Advanced Synthetic Aperture Radar data, Sentinel‐1A data, and Moderate Resolution Imaging Spectroradiometer data were employed to identify the spatio‐temporal characteristics of the ice arch during 2006–2019. Polynya pixels were identified based on the thin ice thickness (TIT), using a threshold of TIT <0.2 m, from which the polynya extent, heat flux, and ice production (IP) were estimated. The results show the different locations of the ice arch in different years, with a mean duration of 132 ± 69 days. The average annual polynya extent over the 14 years is ∼38.8 ± 8 × 103km2, and we found that it is more closely correlated with wind speed during the winter and air temperature during early spring. The average heat flux drops from about 248 W/m2in the winter months to about 34 W/m2in May. The average accumulated IP varies significantly every year, with an average of 144 ± 103 km3, and peak values in March in most years. No apparent interannual trends are shown for the polynya area, heat flux, and IP during 2006–2019. The results also show that IP calculated based on the ice arch data is approximately 25% lower than that obtained by assuming a fixed time, location, and duration for the polynya. The North Water Polynya (NOW) is the area of the highest ice production (IP) in the Arctic. The ice arch is critical to the formation of the NOW. In this study, we used high‐resolution satellite data to identify the spatio‐temporal characteristics of the ice arch during 2006–2019. Then, for the first time, we estimated the IP based on the variable location and duration of the ice arch, and we analyzed the difference with the results previously obtained based on a fixed location and period (FLP) for the polynya. Our results show that the ice arch may locate at the entrance to the Robeson Channel, Smith Sound, or the middle of Kane Basin, and its duration is highly variable. Hence, the heat flux and IP of the NOW fluctuate considerably. Furthermore, the heat flux and IP in our results are approximately 34% and 25% lower than those previously obtained based on FLP, respectively. In addition, we found that air temperature has a greater effect on the polynya extent than wind speed in spring while wind had greater effect in winter. The results of this study will provide more accurate conditions for coupled regional atmosphere‐ice‐ocean models in the Arctic. The spatio‐temporal characteristics of the ice arch is identified from high‐resolution Synthetic Aperture Radar and Moderate Resolution Imaging Spectroradiometer dataThe ice production in the North Water Polynya estimated based on the variable location and duration of the ice arch are presentedAnalysis of the difference with the results estimated based on the fixed location and duration (from December and March) The spatio‐temporal characteristics of the ice arch is identified from high‐resolution Synthetic Aperture Radar and Moderate Resolution Imaging Spectroradiometer data The ice production in the North Water Polynya estimated based on the variable location and duration of the ice arch are presented Analysis of the difference with the results estimated based on the fixed location and duration (from December and March)