Crown Ether Copolymerized Polyimide Film: Enhanced Mechanical, Thermal Properties and Low Dielectric Constant under High Frequency.

Polymer materials with a low dielectric constant and low dielectric loss have the potential to be applied to high-frequency signal transmissions, such as mobile phone antennas and millimeter wave radars. Two types of diamines, 4,4'-diamino-p-tetraphenyl (DPT) and crown ether diamine (CED), were prepared for ternary copolymerization with BPDA in this study. Cross-links with molecular chains were formed, increasing molecular chain distance by utilizing rings of CED. The MPI films exhibit a good thermal performance with the increase in CED addition, with Tg > 380 °C and CTE from -4 × 10-6 K-1 to 5 × 10-6 K-1. The Young's modulus can reach 8.6 GPa, and the tensile strength is above 200 MPa when 5% and 7% CED are introduced. These MPI films exhibit good mechanical performances. The dielectric constant of PI-10% film can go as low as 3.17. Meanwhile, the relationship between dielectric properties and molecular structure has been demonstrated by Molecular Simulation (MS). PI molecules are separated by low dielectric groups, resulting in a decrease in the dielectric constant.

Lathyrane and premyrsinane Euphorbia diterpenes against Alzheimer's disease: Bioinspired synthesis, anti-cholinesterase and neuroprotection bioactivity.

The first systematic acylated diversification of naturally scarce premyrsinane diterpenes, together with their biosynthetic precursors lathyrane diterpene were carried out. Two new series of premyrsinane derivates (1a-32a) and lathyrane derivates (1-32) were synthesized from the naturally abundant lathyrane diterpene Euphorbia factor L3 through a bioinspired approach. The cholinesterase inhibitory and neuroprotective activities of these diterpenes were investigated to explore potential anti-Alzheimer's disease (AD) bioactive lead compounds. In general, the lathyrane diterpenes showed the better acetylcholinesterase (AChE) inhibitory activity than that of premyrsinanes. The lathyrane derivative 17 bearing a 3-dimethylaminobenzoyl moiety showed the best AChE inhibition effect with the IC50 value of 7.1 µM. Molecular docking demonstrated that 17 could bond with AChE well (-8 kal/mol). On the other hand, premyrsinanes showed a better neuroprotection profile against H2O2-induced injury in SH-SY5Y cells. Among them, the premyrsinane diterpene 16a had significant neuroprotective effect with the cell viability rate of 113.5 % at 12.5 µM (the model group with 51.2 %). The immunofluorescence, western blot and reactive oxygen species (ROS) analysis were conducted to demonstrate the mechanism of 16a. Furthermore, a preliminary SAR analysis of the two categories of diterpenes was performed to provide the insights for anti-AD drug development.

Secondary Organic Aerosol Generated from Biomass Burning Emitted Phenolic Compounds: Oxidative Potential, Reactive Oxygen Species, and Cytotoxicity.

Phenolic compounds are largely emitted from biomass burning (BB) and have a significant potential to form SOA (Phc-SOA). However, the toxicological properties of Phc-SOA remain unclear. In this study, phenol and guaiacol were chosen as two representative phenolic gases in BB plumes, and the toxicological properties of water-soluble components of their SOA generated under different photochemical ages and NOx levels were investigated. Phenolic compounds contribute greatly to the oxidative potential (OP) of biomass-burning SOA. OH-adducts of guaiacol (e.g., 2-methoxyhydroquinone) were identified as components of guaiacol SOA (GSOA) with high OP. The addition of nitro groups to 2,5-dimethyl-1,4-benzoquinone, a surrogate quinone compound in Phc-SOA, increased its OP. The toxicity of both phenol SOA (PSOA) and GSOA in vitro in human alveolar epithelial cells decreased with aging in terms of both cell death and cellular reactive oxygen species (ROS), possibly due to more ring-opening products with relatively low toxicity. The influence of NOx was consistent between cell death and cellular ROS for GSOA but not for PSOA, indicating that cellular ROS production does not necessarily represent all processes contributing to cell death caused by PSOA. Combining different acellular and cellular assays can provide a comprehensive understanding of aerosol toxicological properties.

High-performance heterometallic photocatalysts afforded by polyoxometalate synthons for efficient H2 production.

MoS2-based materials have emerged as photoelectric semiconductors characterized by a narrow band gap, high capacity for absorbing visible light, and reduced H2 adsorption energy comparable to Pt. These attributes render them appealing for application in photocatalytic hydrogen production. Despite these advantages, the widespread adoption of MoS2-based materials remains hindered by challenges associated with limited exposure to active sites and suboptimal catalytic hydrogen production efficiency. To address these issues, we have designed and synthesized a new class of highly dispersed bimetallic/trimetallic sulfide materials. This was achieved by developing polyoxometalate synthons containing Ni-Mo elements, which were subsequently reacted with thiourea and CdS. The resulting Ni3S2-MoS2 and Ni3S2-MoS2-CdS materials achieve photocatalytic hydrogen production rates of 2770 and 2873 µmol g-1h-1, respectively. Notably, the rate of 2873 µmol g-1h-1 for Ni3S2-MoS2-CdS surpassed triple (3.23 times) the performance of CdS and nearly sextuple (5.77 times) that of single MoS2. These materials outperformed the majority of MoS2-based photocatalysts. Overall, this study introduces a straightforward methodology for synthesizing bimetallic/trimetallic sulfides with enhanced photocatalytic H2 evolution performance. Our findings underscore the potential of transition metal sulfide semiconductors in the realm of photocatalysis and pave the way for the development of more sustainable energy production systems.

Computational Interpersonal Communication Model for Screening Autistic Toddlers: A Case Study of Response-to-Name.

Interpersonal communication facilitates symptom measures of autistic sociability to enhance clinical decision-making in identifying children with autism spectrum disorder (ASD). Traditional methods are carried out by clinical practitioners with assessment scales, which are subjective to quantify. Recent studies employ engineering technologies to analyze children's behaviors with quantitative indicators, but these methods only generate specific rule-driven indicators that are not adaptable to diverse interaction scenarios. To tackle this issue, we propose a Computational Interpersonal Communication Model (CICM) based on psychological theory to represent dyadic interpersonal communication as a stochastic process, providing a scenario-independent theoretical framework for evaluating autistic sociability. We apply CICM to the response-to-name (RTN) with 48 subjects, including 30 toddlers with ASD and 18 typically developing (TD), and design a joint state transition matrix as quantitative indicators. Paired with machine learning, our proposed CICM-driven indicators achieve consistencies of 98.44% and 83.33% with RTN expert ratings and ASD diagnosis, respectively. Beyond outstanding screening results, we also reveal the interpretability between CICM-driven indicators and expert ratings based on statistical analysis.

Immune Responses in Discharged COVID-19 Patients With and Without Long COVID Symptoms.

The immune mechanisms of long coronavirus disease 2019 (COVID) are not yet fully understood. We aimed to investigate the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)-specific memory immune responses in discharged COVID-19 patients with and without long COVID symptoms. In this cross-sectional study, we included 1041 hospitalized COVID-19 patients with the original virus strain in Wuhan (China) 12 months after initial infection. We simultaneously conducted a questionnaire survey and collected peripheral blood samples from the participants. Based on the presence or absence of long COVID symptoms during the follow-up period, we divided the patients into 2 groups: a long COVID group comprising 480 individuals and a convalescent group comprising 561 individuals. Both groups underwent virus-specific immunological analyses, including enzyme-linked immunosorbent assay, interferon-γ-enzyme-linked immune absorbent spot, and intracellular cytokine staining. At 12 months after infection, 98.5% (1026/1041) of the patients were found to be seropositive and 93.3% (70/75) had detectable SARS-CoV-2-specific memory T cells. The long COVID group had significantly higher levels of receptor binding domain (RBD)-immunoglobulin G (IgG) levels, presented as OD450 values, than the convalescent controls (0.40 ± 0.22 vs 0.37 ± 0.20; P = .022). The magnitude of SARS-CoV-2-specific T-cell responses did not differ significantly between groups, nor did the secretion function of the memory T cells. We did not observe a significant correlation between SARS-CoV-2-IgG and magnitude of memory T cells. This study revealed that long COVID patients had significantly higher levels of RBD-IgG antibodies when compared with convalescent controls. Nevertheless, we did not observe coordinated SARS-CoV-2-specific cellular immunity. As there may be multiple potential causes of long COVID, it is imperative to avoid adopting a "one-size-fits-all" approach to future treatment modalities.

Green finance reform and application intensity of chemical fertilizer and pesticide: policy evidence from China.

The environmental hazards resulting from the excessive application of pesticides and fertilizers have been an inevitable agricultural production issue in various countries around the world. New technologies and policies are constantly trying to improve their application efficiency. This paper utilizes panel data of the provincial level in China from 2009 to 2019 to empirically study the effect of green finance reform policies on the chemical fertilizer application intensity (FAI) and pesticide application intensity (PAI). Standard difference-in-differences (DID), synthetic DID, difference-in-difference-in differences (DDD), and spatial DID models are constructed for specific empirical analysis. The findings can be concluded as follows: (1) A unit of the green finance reform policy reduces FAI by 0.0144 and PAI by 1.7921 by promoting green technology innovation. (2) Government financial extractive capacity hinders the reduction effect of green finance on PAI. (3) Coastal geographical location is conducive to reducing PAI through green finance reform. (4) FAI and PAI show positive spatial autocorrelations, and the influence of green finance reform overflows to surrounding areas. The research results can provide policy references for countries around the world to promote the green development of agriculture and reduce environmental pollution.

Diffusivities and Atomic Mobilities in BCC Ti-Fe-Cr Alloys.

In this research, the diffusion behaviors within the Ti-Fe-Cr ternary system were examined at the temperatures of 1273 K and 1373 K through the diffusion couple technique. This study led to the determination of both ternary inter-diffusion and impurity diffusion coefficients in the body-centered cubic (bcc) phase for the Ti-Fe-Cr alloy, utilizing the Whittle-Green and Hall methods. The statistics show that the average diffusion coefficients D˜FeFeTi and D˜CrCrTi measured at 1273 K were 1.34 × 10-12 and 3.66 × 10-13, respectively. At 1373 K, the average values of D˜FeFeTi and D˜CrCrTi were 4.89 × 10-12 and 1.43 × 10-12. By adopting the CALPHAD method, a self-consistent database for atomic mobility in the bcc phase of the Ti-Fe-Cr system was established. This database underwent refinement by comparing the newly acquired diffusion coefficients with data from the existing literature. Diffusion simulations for the diffusion couples were performed, drawing on the established database. The error between the simulated diffusion coefficient and the experimental measurement data is within 15%, and the simulated data of the component distance distribution and diffusion path are in good agreement with the experimental data. The simulations generated results that aligned well with the observed experimental diffusion characteristics, thereby affirming the reliability and accuracy of the database.

Ozone and its precursors at an urban site in the Yangtze River Delta since clean air action plan phase II in China.

In response to regional ozone (O3) pollution, Chinese government has implemented air pollution control measures in recent years. Here, a case study was performed at an O3-polluted city, Wuhu, in Yangtze River Delta region of China to investigate O3 variation trend and the relationship to its precursors after implementation of Clean Air Action Plan Phase II, which aims to reduce O3 pollution. The results showed that peak O3 concentration was effectively reduced since Clean Air Action Plan Phase II. Due to significant NOx reduction, O3 formation tended to shift from volatile organic compound (VOC)-limited regimes to NOx-limited regimes during 2018-2022. VOC/NOx ratios measured in 2022 revealed that peak O3 concentration tended to respond positively to NOx. Apart from high-O3 period, Wuhu was still in a VOC-limited regime. The relationship of maximum daily 8-h ozone average and NO2 followed a lognormal distribution with an inflection point at 20 µg m-3 of NO2, suggesting that Wuhu should conduct joint control of VOC and NOx with a focus on VOC reduction before the inflection point. Alkenes and aromatics were suggested to be preferentially controlled due to their higher ozone formation potentials. Using random forest meteorological normalization method, meteorology had a positive effect on O3 concentration in 2018, 2019 and 2022, but a negative effect in 2020 and 2021. The meteorology could explain 44.0 ± 19.1% of the O3 variation during 2018-2022. High temperature favors O3 production and O3 pollution occurred more easily when temperature was over 25 °C, while high relative humidity inhibits O3 generation and no O3 pollution was found at relative humidity above 70%. This study unveils some new insights into the trend of urban O3 pollution in Yangtze River Delta region since Clean Air Action Plan Phase II and the findings provide important references for formulating control strategies against O3 pollution.

Effect of Corticosteroids on Long-term Humoral and Memory T-Cell Responses in Follow-up Visit of Hospitalized Patients With COVID-19.

BACKGROUND: Corticosteroids have beneficial effects in improving outcomes in hospitalized patients with severe COVID-19 by suppressing excessive immune responses. However, the effect of corticosteroids on the humoral and T-cell responses of survivors of COVID-19 1 year after infection remains uncertain because it relates to the extent of immediate, antigen-specific defense provided by protective memory. RESEARCH QUESTION: What is the effect of corticosteroids on long-term humoral and T-cell immune responses? STUDY DESIGN AND METHODS: In this retrospective cohort study conducted at a single center, we analyzed data from a cohort who had survived COVID-19 to compare the 1-year seropositivity and titer changes in neutralizing antibodies (NAbs) and SARS-CoV-2-specific antibodies. Additionally, we evaluated the magnitude and rate of SARS-CoV-2-specific T-cell response in individuals who received corticosteroids during hospitalization and those who did not. RESULTS: Our findings indicated that corticosteroids do not statistically influence the kinetics or seropositive rate of NAbs against the Wuhan strain of SARS-CoV-2 from 6 months to 1 year. However, subgroup analysis revealed a numerical increase of absolute NAbs titers, from 20.0 to 28.2, in categories where long-term (> 15 days) and high-dose (> 560 mg) corticosteroids are administered. Similarly, corticosteroids showed no significant effect on nucleoprotein and receptor-binding domain IgG at 1 year, except for spike protein IgG (ß, 0.08; 95% CI, 0.04-0.12), which demonstrated a delayed decline of titers. Regarding T-cell immunity, corticosteroids did not affect the rate or magnitude of T-cell responses significantly. However, functional assessment of memory T cells revealed higher interferon-γ responses in CD4 (ß, 0.61; 95% CI, 0.10-1.12) and CD8 (ß, 0.63; 95% CI, 0.11-1.15) memory T cells in the corticosteroids group at 1 year. INTERPRETATION: Based on our findings, short-term and low-dose corticosteroid therapy during hospitalization does not have a significant effect on long-term humoral kinetics or the magnitude and rate of memory T-cell responses to SARS-CoV-2 antigens. However, the potential harmful effects of long-term and high-dose corticosteroid use on memory immune responses require further investigation.

Comparison of three source apportionment methods based on observed and initial HCHO in Taiyuan, China.

Identifying the sources of formaldehyde (HCHO) is key to reducing the pollution of HCHO and ozone (O3) on the ground level. Using the same datasets applied to the positive matrix factorization (PMF) model by (Hua et al., 2023), the initial concentrations of HCHO were estimated using the photochemical age and the sources of observed and initial HCHO were apportioned based on multiple linear regression (MLR) and photochemical age-based parameterization (PCAP) methods. These results suggest that the source of the initial HCHO can better reflect its contribution. The secondary formation contributed to 49.3-69.1 % of initial HCHO at four sites in Taiyuan based on MLR, which was higher (7.4-36.2 %) than the contributions of secondary formation from observed HCHO. The HCHO was mainly affected by anthropogenic secondary (10.8-34.4 %) and background sources (17.4-78.7 %) based on the PCAP method. We compared the results of the HCHO sources from the MLR, PCAP, and PMF models under photochemical loss. There was good agreement among the emission ratios of acetylene-based HCHO obtained by the different methods at the four sites. The correlation analysis of different source apportionment methods illustrated that primary emissions from the PCAP and the MLR model had the greatest correlation (0.22-0.60). Secondary formations from the PMF and MLR models showed good correlations at all four sites, with R values ranging from 0.42 to 0.83. The HCHO peak of diurnal variation simulated by MLR appeared late compared to the other methods, and the difference in daily variation of HCHO from the PMF model was significantly higher than that of PCAP and MLR. The overlapping conclusions of different source apportionment methods should be considered and used to guide efforts to improve air quality.

A field diagnostic method for rapid and sensitive detection of mpox virus.

The mpox outbreak has subdued with fewer reported cases at the present in high-income countries. It is known that mpox virus (MPXV) infection has been epidemic for more than 50 years in African countries. The ancestral MPXV strain has changed into multiple clades, indicating the ongoing evolution of MPXV, which reflects the historical neglect of mpox in Africa, especially after smallpox eradication, and bestows the danger of more severe mpox epidemics in the future. It is thus imperative to continue the development of mpox diagnostics and treatments so we can be prepared in the event of a new mpox epidemic. In this study, we have developed an MPXV detection tool that leverages the recombinase-aid amplification assay by integrating lateral flow strips (RAA-LF) and one-step sample DNA preparation, with visible readout, no need of laboratory instrument, and ready for field deployment. The detection limit reaches 10 copies per reaction. The performance of our RAA-FL assay in diagnosing mpox clinical samples is on par with that of the quantitative polymerase chain reaction (PCR) assay. Taken together, we have developed a point-of-care RAA-LF method of high accuracy and sensitivity, readily deployable for field detection of MPXV. This diagnostic tool is expected to improve and accelerate field- and self-diagnosis, allow timely isolation and treatment, reduce the spread of MPXV, thus effectively mitigate MPXV outbreak in the future.

Design of a Zn-based nanozyme injectable multifunctional hydrogel with ROS scavenging activity for myocardial infarction therapy.

The existing strategies for myocardial infarction therapy mainly focus on reinstating myocardial blood supply, often disregarding the intrinsic and intricate microenvironment created by elevated levels of reactive oxygen species (ROS) that accompanies myocardial infarction. This microenvironment entails cardiomyocytes apoptosis, substantial vascular cell death, excessive inflammatory infiltration and fibrosis. In such situation, the present study introduces a zinc-based nanozyme injectable multifunctional hydrogel, crafted from ZIF-8, to counteract ROS effects after myocardial infarction. The hydrogel exhibits both superoxide dismutase (SOD)-like and catalase (CAT)-like enzymatic activities, proficiently eliminating surplus ROS in the infarcted region and interrupting ROS-driven inflammatory cascades. Furthermore, the hydrogel's exceptional immunomodulatory ability spurs a notable transformation of macrophages into the M2 phenotype, effectively neutralizing inflammatory factors and indirectly fostering vascularization in the infarcted region. For high ROS and demanding for zinc of the infarcted microenvironment, the gradual release of zinc ions as the hydrogel degrades further enhances the bioactive and catalytic performance of the nanozymes, synergistically promoting cardiac function post myocardial infarction. In conclusion, this system of deploying catalytic nanomaterials within bioactive matrices for ROS-related ailment therapy not only establishes a robust foundation for biomedical material development, but also promises a holistic approach towards addressing myocardial infarction complexities. STATEMENT OF SIGNIFICANCE: Myocardial infarction remains the leading cause of death worldwide. However, the existing strategies for myocardial infarction therapy mainly focus on reinstating myocardial blood supply. These therapies often ignore the intrinsic and intricate microenvironment created by elevated levels of reactive oxygen species (ROS). Hence, we designed an injectable Zn-Based nanozyme hydrogel with ROS scavenging activity for myocardial infarction therapy. ALG-(ZIF-8) can significantly reduce ROS in the infarcted area and alleviate the ensuing pathological process. ALG-(ZIF-8) gradually releases zinc ions to participate in the repair process and improves cardiac function. Overall, this multifunctional hydrogel equipped with ZIF-8 makes full use of the characteristics of clearing ROS and slowly releasing zinc ions, and we are the first to test the therapeutic efficacy of Zinc-MOFs crosslinked-alginate hydrogel for myocardial infarction.

Epigenetic Regulatory Axis MIR22-TET3-MTRNR2L2 Represses Fibroblast-Like Synoviocyte-Mediated Inflammation in Rheumatoid Arthritis.

OBJECTIVE: The specific role of fibroblast-like synoviocytes (FLSs) in the pathogenesis of rheumatoid arthritis (RA) is still not fully elucidated. This study aimed to explore the molecular mechanisms of epigenetic pathways, including three epigenetic factors, microRNA (miRNA)-22 (MIR22), ten-eleven translocation methylcytosine dioxygenase 3 (TET3), and MT-RNR2 like 2 (MTRNR2L2), in RA-FLSs. METHODS: The expression of MIR22, TET3, and MTRNR2L2 in the synovium of patients with RA and arthritic mice were determined by fluorescence in situ hybridization, quantitative polymerase chain reaction (qPCR), immunohistochemistry, and Western blot. Mir22-/- and Tet3+/- mice were used to establish a collagen antibody-induced arthritis (CAIA) model. Mir22 angomir and Tet3 small interfering RNA (siRNA) were used to illustrate the therapeutic effects on arthritis using a collagen-induced (CIA) model. Bioinformatics, luciferase reporter assay, 5-hydroxymethylcytosine (5hmC) dot blotting, chromatin immunoprecipitation-qPCR, and hydroxymethylated DNA immunoprecipitation were conducted to show the direct repression of MIR22 on the TET3 and transcriptional activation of TET3 on MTRNR2L2. RESULTS: The Mir22-/- CAIA model and RA-FLS-related in vitro experiments demonstrated the inhibitory effect of MIR22 on inflammation. MIR22 can directly inhibit the translation of TET3 in RA-FLSs by binding to its 3' untranslated region in TET3. The Tet3+/- mice-established CAIA model showed less severe symptoms of arthritis in vivo. In vitro experiments further confirmed the proinflammatory effect of TET3 in RA. In addition, the CIA model was used to validate the therapeutic effects of Mir22 angomir and Tet3 siRNA. Finally, TET3 exerts its proinflammatory effect by promoting 5hmC production in the promoter of its target MTRNR2L2 in RA-FLSs. CONCLUSION: The key role of the MIR22-TET3-MTRNR2L2 pathway in RA-FLSs provided an experimental basis for further studies into the pathogenesis and related targets of RA from the perspective of FLSs.

Mixing state and influence factors controlling diurnal variation of particulate nitrophenol compounds at a suburban area in northern China.

Nitrophenols have received extensive attention due to their strong light-absorbing ability in the near-ultraviolet-visible region, which could be influenced by the atmospheric processes of nitrophenols. However, our knowledge and understanding of the formation and evolution of nitrophenols are still in the nascent stages. In the present study, the mixing states of four mononitrophenol particles (i.e., nitrophenol, methynitrophenol, nitrocatechol, and methoxynitrophenol), and one nitropolycyclic aromatic hydrocarbon particles (i.e., nitronaphthol (NN)) were investigated using a single-particle aerosol mass spectrometer (SPAMS) in November 2019 in Qingdao, China. The results showed, for the first time, that mononitrophenols and NN exhibit different mixing states and diurnal variations. Four mononitrophenols were internally mixed well with each other, and with organic acids, nitrates, potassium, and naphthalene. The diurnal variation in the number fraction of mononitrophenols presented two peaks at 07:00 to 09:00 and 18:00 to 20:00, and a valley at noon. Atmospheric environmental conditions, including NO2, O3, relative humidity, and temperature, can significantly influence the diurnal variation of mononitrophenols. Multiple linear regression and random forest regression models revealed that the main factors controlling the diurnal variation of mononitrophenols were photochemical reactions during the day and aqueous-phase reactions during the night. Unlike mononitrophenols, about 62-83% of NN were internally mixed with [NH4]+ and [H(NO3)2]-, but not with organic acids and potassium. The diurnal variation of NN was also different from that of mononitrophenols, generally increased from 17:00 to 10:00 and then rapidly decreaed from 11:00 to 16:00. These results imply that NN may have sources and atmospheric processes that are different from mononitrophenols. We speculate that this is mostly controlled by photochemical reactions and mixing with [NH4]+, which may influence the diurnal variation of NN in the ambient particles; however, this requires further confirmation. These findings extend our current understanding of the atmospheric formation and evolution of nitrophenols.

Secondary inorganic aerosols and aerosol acidity at different PM2.5 pollution levels during winter haze episodes in the Sichuan Basin, China.

Wintertime fine particle (PM2.5) pollution remains to be perplexing air quality problems in many parts of China. In this study, PM2.5 compositions and aerosol acidity at different pollution levels at an urban cite in the southwest China's Sichuan Basin were investigated during a sustained winter haze episode. Organic matter was the most abundant component of PM2.5, followed by nitrate, sulfate and ammonium. Shares of organic aerosol in PM2.5 mass decreased with the elevated PM2.5 levels, while the enhancements of sulfate and secondary organic aerosol were much less than that of nitrate and ammonium during heavy pollution with increased ratios of nitrate to sulfate, implying a significant role of nitrate in the haze formation. Results also suggest the nighttime chemistry might contribute substantially to the formation of nitrate under severe pollutions. The daily average aerosol pH showed a decreasing trend with the elevated levels of PM2.5, and this increased aerosl acidity was mainly due to the fast rising secondary inorganic aerosol (SIA) concentration, with the increase in hydronium ion concentration in air (Hair+) surpassing the dilution effect of elevated aerosol liquid water content (LWC). Thermodynamic model calculations revealed that the air environment was NH3-rich with total NHx (NH3 + NH4+) greater than required NHx, and the aerosol pH exponentially declined with the decreasing excess NHx (p < 0.01). This study demonstrated that under air stagnation and NH3-rich environment during winter, the raised relative humidity (RH) would lead to an increase in LWC and thereby facilitate the aqueous chemistry processes with the neutralization capacity of NH3 to form sulfate and nitrate, which would further increase the LWC and lower the pH. This self-amplifying SIA formation might be crucial to the severe PM2.5 pollution and haze events during winter, and therefore cutting both NOx and NH3 emissions would benefit stopping the self-amplification.

Nitrogen doped 1 T/2H mixed phase MoS2/CuS heterostructure nanosheets for enhanced peroxidase activity.

Heteroatom doping and phase engineering are effective ways to promote the catalytic activity of nanoenzymes. Nitrogen-doped 1 T/2H mixed phase MoS2/CuS heterostructure nanosheets N-1 T/2H-MoS2/CuS are prepared by a simple hydrothermal approach using polyoxometalate (POM)-based metal-organic frameworks (MOFs) (NENU-5) as a precursor and urea as nitrogen doping reagent. The XPS spectroscopy (XPS) and Raman spectrum of N-1 T/2H-MoS2/CuS prove the successful N-doping. NENU-5 was used as the template to prepare 1 T/2H-MoS2/CuS with high content of 1 T phase by optimizing the reaction time. The use of urea as nitrogen dopant added to 1 T/2H-MoS2/CuS, resulted in N-1 T/2H-MoS2/CuS with an increase in the content of the 1 T phase from 80 % to 84 % and higher number of defects. N-1 T/2H-MoS2/CuS shows higher peroxidase activity than 1 T/2H-MoS2/CuS and a catalytic efficiency (Kcat/Km) for H2O2 twice as high as that of 1 T/2H-MoS2/CuS. The enhanced catalytic activity has probably been attributed to several reasons: (i) the insertion of urea during the hydrothermal process in the S-Mo-S layer of MoS2, causing an increase in the interlayer spacing and in 1 T phase content, (ii) the replacement of S atoms in MoS2 by N atoms from the urea decomposition, resulting in more defects and more active sites. As far as we know, N-1 T/2H-MoS2/CuS nanosheets have the lowest detection limit (0.16 µm) for the colorimetric detection of hydroquinone among molybdenum disulfide-based catalysts. This study affords a new approach for the fabrication of high-performance nanoenzyme catalysts.

Residual Immunity from Smallpox Vaccination and Possible Protection from Mpox, China.

Among persons born in China before 1980 and tested for vaccinia virus Tiantan strain (VVT), 28.7% (137/478) had neutralizing antibodies, 71.4% (25/35) had memory B-cell responses, and 65.7% (23/35) had memory T-cell responses to VVT. Because of cross-immunity between the viruses, these findings can help guide mpox vaccination strategies in China.