Isomeric Dual-Pore Two-Dimensional Covalent Organic Frameworks.

Two-dimensional (2D) covalent organic frameworks (COFs) with hierarchical porosity have been increasingly recognized as promising materials in various fields. Besides, the 2D COFs with kagome (kgm) topology can exhibit unique optoelectronic features and have extensive applications. However, rational synthesis of the COFs with kgm topology remains challenging because of competition with a square-lattice topology. Herein, we report two isomeric dual-pore 2D COFs with kgm topology using a novel geometric strategy to reduce the symmetry of their building blocks, which are four-armed naphthalene-based and azulene-based isomeric monomers. Owing to the large dipole moment of azulene, as-prepared azulene-based COF (COF-Az) possesses a considerably narrow band gap of down to 1.37 eV, which is much narrower than the naphthalene-based 2D COF (COF-Nap: 2.28 eV) and is the lowest band gap among reported imine-linked dual-pore 2D COFs. Moreover, COF-Az was used as electrode material in a gas sensor and exhibits high selectivity for NO2, including a high response rate (58.7%) to NO2 (10 ppm), fast recovery (72 s), up to 10 weeks of stability, and resistance to 80% relative humidity, which are superior to those of reported COF-based NO2 gas sensors. The calculation and in situ experimental results indicate that the large dipole moment of azulene boosts the sensitivity of the imine linkages. The usage of isomeric building blocks not only enables the synthesis of 2D COFs with isometric kgm topology but also provides an azulene-based 2D platform for studying the structure-property correlations of COFs.

A study of immunoprophylaxis failure and risk factors of hepatitis B virus mother-to-infant transmission.

UNLABELLED: Hepatitis B virus (HBV) infection is of high prevalence in China. Mother-to-infant transmission is the major route for HBV transmission and subsequent chronicity. This study aimed to investigate current HBsAg-positive rate among pregnant women and immunoprophylaxis outcome in China. Multicenter prospective study was conducted in 10 centers. From 2008 to 2012, 67,720 pregnant women were screened and 1,150 HBsAg-carrier mothers and their infants aged 8-12 months were studied in four out of all centers, among whom HBV markers (HBsAg, HBsAb, HBeAg, HBeAb, and HBcAb) and HBV DNA (in three centers) were measured. The results showed that HBsAg-positive rate of pregnant women was 6.7 % (4,533/67,720) and infants' immunoprophylaxis failure rate was 3.4 % (39/1,150). Immunoprophylaxis failure infants were all born to mothers of HBeAg-positive and HBV DNA ≥6 log10 copies/ml. Among infants of HBeAg-positive mothers, multivariable analyses showed the following: mother's age <28 years vs ≥28 years, RR = 0.157, 95 % confidence interval (CI) [0.067, 0.369], p = 0.000; Neonates receiving vaccine vs vaccine plus hepatitis B immune globulin (HBIG), RR = 0.371, 95 % CI [0.167, 0.825], p = 0.015. Pregnant women receiving HBIG in the third trimester, vaginal delivery and breastfeeding had no significant effects on HBV mother-to-infant transmission. CONCLUSIONS: Pregnant women are still of high HBsAg prevalence in China. HBV mother-to-infant transmission still occurs after passive-active immunization. Pregnant women of high HBV replication levels are the major risk population of HBV mother-to-infant transmission. Passive-active immunization is necessary for neonates of HBeAg-positive mothers. Mother's age <28 years and neonate receiving vaccine only were the risk factors for HBV mother-to-infant transmission. Breastfeeding did not put children at risk of mother-to-infant transmission.

Well-defined asymmetric nitrogen/carbon-coordinated single metal sites for carbon dioxide conversion.

Asymmetric nitrogen/carbon-coordinated single metal sites (M-NxC4-x) outperform symmetric M-N4 sites in carbon dioxide (CO2) electroreduction. However, the challenge of crafting well-defined M-NxC4-x sites complicates the understanding of their structure-catalytic performance relationship. In this study, we employ metallized N-confused tetraphenylporphyrin (M-NCTPP) to investigate CO2 conversion on M-N3C1 sites using both density functional theory and experimental methods. The optimal cobalt (Co)-N3C1 site (Co-NCTPP) achieves a current density of 500 mA cm-2 and a carbon monoxide Faraday efficiency exceeding 90 % at -1.25 V vs. the reversible hydrogen electrode, surpassing the performance of Co-N4 (Co-TPP). This research introduces a novel approach for designing and synthesizing high-activity heteroatom-anchored single metal sites, advancing fundamental understanding in the field.

Modulating intramolecular electron and proton transfer kinetics for promoting carbon dioxide conversion.

A novel pentagon-heptagon paired azulene group that possesses a large dipole moment is immobilized onto a porphyrin. The as-prepared azulene iron porphyrin exhibits a narrower bandgap and higher electrocatalytic CO2 reduction activity than the pristine iron porphyrin. The maximum CO faradaic efficiency reaches 99.9%, which is the state-of-the-art value among molecular catalysts.

Breast feeding and immunoprophylaxis efficacy of mother-to-child transmission of hepatitis B virus.

OBJECTIVE: This study was designed to explore if hepatitis B virus (HBV) may be transmitted via breast milk through mother-to-child transmission (MTCT), and assay the immunoprophylaxis efficacy after passive-active immunization. METHOD: From year 2008 to 2012, 67,720 pregnant women were screened and 1186 HBsAg-carrier mothers and their infants aged 8-12 months were followed in multi-centers of China, among whom HBV markers (HBsAg, HBsAb, HBeAg, HBeAb and HBcAb) and HBV-DNA were measured. RESULTS: HBsAg positive rate of pregnant women was 6.7% (4533/67,720) and infants' immunoprophylaxis failure rate was 3.3% (39/1186). Immunoprophylaxis failure infants were all born to mothers of HBeAg positive and HBV-DNA >6 log10 copies/ml. Among infants of HBeAg positive mothers, HBV infection rate was 9.0% and HBsAg positive rate was 8.3% in breast-feeding group versus 9.2% in formula-feeding group, P=0.761. Occurrence of perinatal HBV infection was indicated in uterus or during delivery. Different feeding patterns had no effects on HBsAb conversion of infants with the implementation of immunization. CONCLUSIONS: HBsAg prevalence rate of pregnant women enrolled was 6.7% and immunoprophylaxis failure rate of infants was 3.3%, while the infection rate reached 9.0% in infants of HBeAg positive mothers. Breast feeding did not increase the occurrence of HBV MTCT.