Maternal antibodies transported across the placenta can provide vital immunity against infectious pathogens for infants. We here examine maternal antibody (MA) levels and their association with neonatal antibody levels. Pregnant women of gestational age ≥35 weeks were enrolled at a Guangzhou China hospital and mother-infant paired sera were collected. Measles IgG antibody was detected using ELISA assay, neutralizing antibodies titers against coxsackievirus A16 (CA16), enterovirus 71 (EV71), PV I-III and HIV-1 were performed. 711 mother-infant pairs were enrolled and positive relationships for paired serums were found (r: 0.683–0.918). 81.6%, 87.0%, and 82.3% of mothers, and 87.3%, 72.7%, and 72.2% of newborns were positive for measles, CA16 and EV71 antibodies respectively. The highest Neonatal: maternal ratio (NMR) was found in measles (1.042) and the ratios for the other pathogens ranged from 0.84 to 1.00. Linear regressions showed that log(NMR) decreased by a factor of 0.04–15.43 as log(MA) levels increased. A second analysis restricted to maternal positive measles sera revealed that MA measles of was still inversely associated with NMR. Low NMR was found in high MA HIV + serums among 22 paired sera. MA levels appear to play a role determining transplacental antibody transfer; further study is needed to reveal the mechanism.

BackgroundDengue virus (DENV) infection is the most prevalent arthropod-borne viral infection in tropical and subtropical regions worldwide. Guangzhou has the ideal environment for DENV transmission and DENV epidemics have been reported in this region for more than 30 years.MethodsInformation for DENV infection cases in Guangzhou from 2001 to 2010 were collected and analyzed. The DENV strains were cultured and isolated from patients’ sera. Viral RNA was extracted from cell culture supernatants. cDNA was synthesized by reverse transcription PCR. Phylogenetic trees of four DENV serotypes were constructed respectively.ResultsIn total, 2478 DENV infection cases were reported; 2143 of these (86.43%) occurred during 3 months of the year: August, September and October. Of these, 2398 were local cases (96.77%) and 80 were imported cases (3.23%). Among the imported cases, 69 (86.25%) were from Southeast Asian countries. From the 90 isolated strains, 66.67%, 3.33%, 14.44%, and 15.56% belonged to DENV serotypes 1, 2, 3, and 4, respectively. DENV-1 was predominant in most of the years, including during 2 outbreaks in 2002 and 2006; however, none of the strains or genotypes identified in this study were found to be predominant. Interestingly, DENV strains from different years had different origins. Moreover, the strains from each year belonged to different serotypes and/or genotypes.ConclusionsSoutheast Asia countries were found to be the possible source of DENV in Guangzhou. These findings suggest that there is increasing diversity in DENV strains in Guangzhou, which could increase the risk of DENV outbreaks in the near future.

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This study investigated how teachers in China perceived the effects of online instruction on mathematics learning and examined the challenges they encountered when the country shifted to online instruction during the COVID-19 pandemic. We interviewed 152 mathematics teachers from 20 cities (municipalities) or provinces in China and adopted the four-component didactic tetrahedron model (teacher, technology, student, and mathematics) to identify their struggles with technology, teacher–student interactions, and delivery of mathematics instruction. Results showed that the teachers believed that the effectiveness of online teaching largely depends on student self-discipline. Analysis suggested a need to expand technology use during instruction, reshape the way teachers interact with students, and reorganize teaching methods in face-to-face classroom instruction. This research provided insights into integrating technology with instructional practice, the critical role of teachers in online learning, and other factors that may determine the effectiveness of online teaching.

Mathematical thinking (MT) has been one of the most important goals for mathematics education as it can support sustainable mathematics learning. Its role in school mathematics has recently been explicitly identified as one of “Four Basics” in the latest national curriculum standard for compulsory education, which is seen as one of the prominent features of Chinese mathematics education. This paper reviewed definitions, descriptions, and explanations from a historical perspective and aimed to provide a comprehensive and contemporary conceptualization for MT in a Chinese context, which can be applied as a comparison to MT in English works. To achieve this, document analysis was applied in this study. Major official documents, papers, and books were reviewed to see the process of MT conceptualization given by the policy makers and researchers. Results indicated that MT places more emphasis on the process of mathematical methods application in problem solving, such as the method of combination of symbolic and graphic mathematics. Mathematical thought is also recommended by Chinese researchers to help students think like mathematicians. Another major characteristic is that the classification of major types of MT is usually focused on that which can make the concept more understandable.

In the perspective of fossil fuel depletion, the importance of renewable and substitute fuels is remarkable. In this study, clean liquid-fuel was obtained from tar through catalytic hydrorefining method. Hydrorefining catalysts were prepared by impregnation, containing tungsten-nickel (W-Ni), molybdenum-nickel (Mo-Ni), tungsten-molybdenum-nickel (W-Mo-Ni), and tungsten-molybdenum-cobalt (W-Mo-Co). γ-alumina was used as catalysts supporter. The clean liquid fuel product was analyzed by Fourier transform infrared spectroscopy, gas chromatography-mass spectrometry, elemental analyzer, octane number for gasoline fraction and cetane-number for diesel fraction, and Engler distillation range. The rules of sulfur and nitrogen content were also investigated. The overall product yield was up to 97%, and the sulfur and nitrogen content was less than 70 ppm. The W-Mo-Ni/γ-Al2O3 catalyst showed high performance in catalytic hydrofinishing and good stabilization under required conditions.

In the last decade, micro-lectures have been widely used to teach mathematics, but only a few studies have examined the factors affecting teachers’ intentions of using micro-lectures. As teachers are key to integrating modern technologies such as micro-lectures into students’ learning processes, knowledge about teachers’ intentions in this regard could be of particular importance. This study aimed to analyze the behavioral intention (BI) of mathematics teachers in using micro-lectures in mathematics in China, and identify the most influential factors involved, for the very first time. The Unified Theory of Acceptance and Use of Technology (UTAUT) model was used as a design model to investigate teachers’ BIs concerning the use of micro-lectures, and we used an online questionnaire to collect quantitative data. The participants in our research were 174 mathematics teachers from China, 166 of whom provided us with evaluable questionnaire data. Furthermore, partial least squares (PLS) regression was used, and hypothesis testing was performed with the Smart-PLS software. From the results, BI was positively affected by Performance Expectancy (PE), Effort Expectancy (EE), and Social Influence (SI). BI and facility conditions also had positive effects on user behavior; in contrast to other studies, SI had the most significant positive effect on BIs in our study. Our findings could provide insights into both future strategies for successful technology integration in mathematics classes and into mathematics teachers’ intentions towards integrating technologies into mathematics teaching.

The incorporation of two-dimensional MoS 2 nanostructures with other semiconductors used in photoelectrocatalytic (PEC) water-splitting for hydrogen (H 2 ) production has been a very promising and eco-friendly approach for providing sustainable clean energy. Herein, atomic-layer MoS 2 nanoflakes with tuned morphologies, including dendritic, semicompact, fractal, and compact shapes, are grown by design on a rutile-TiO 2 (001) single crystal surface via a facile chemical vapor deposition method. The PEC hydrogen evolution reaction (HER) of the MoS 2 /TiO 2 hydride electrodes with four different MoS 2 morphologies is comparatively explored. Enhanced PEC HER performance is observed for the composite electrodes, where the H 2 production efficiency sequentially increases from the fractal to the compact triangular to the semicompact and finally to the dendritic MoS 2 nanoflakes. The mechanism of improvement of the PEC HER efficiency can, on the one hand, be accounted for by the corresponding increase in the effective edge length of the active sites in the MoS 2 layer. On the other hand, band realignment at the MoS 2 /TiO 2 interface favors the transfer of the photogenerated electrons in TiO 2 to the active sites of MoS 2 , thereby also leading to enhanced H 2 production. The dendritic MoS 2 nanoflakes on TiO 2 , which serve as excellent long-wavelength light absorbers with the enlarged effective edge length as active sites, and the band realignment, which facilitates the migration of the photogenerated electrons onto the active sites of MoS 2 , play multiple roles in enhancing the PEC HER efficiency for the dendritic MoS 2 /TiO 2 composite electrodes. We hope that this work provides a feasible route toward the development of efficient hybrid HER catalysts.