Knowledge and intake of folic acid to prevent neural tube defects among pregnant women in urban China: a cross-sectional study.

BACKGROUND: The prevalence of neural tube defects (NTDs) in China declined during 2000-2017 with periconceptional folic acid (FA) supplementation, which is effective in reducing the risk of birth defects. We aimed to assess the knowledge and actual use of FA among Chinese pregnant women and to explore factors associated with FA use before pregnancy. METHODS: All data were collected in face-to-face interviews during health visits among pregnant women. We collected information about knowledge and use of FA supplements and demographic, socioeconomic, and health status. One maternity and childcare hospital was chosen in each of four cities: Beijing, Huaibei, Kunming, and Haikou. In total, 435 pregnant women were randomly recruited for interviews conducted from June to December 2016. RESULTS: A total of 428 pregnant women were included in this survey. Of these, 82.0% (351/428) knew that FA can prevent NTDs, and 75.9% (325/428) knew the correct time to take FA. Overall, 65.9% (282/428) of women knew both that FA can prevent NTDs and the recommended time to take FA before pregnancy. Approximately 95.1% (407/428) of women reported having ever taken FA, only 46.3% (198/428) had begun to take FA supplementation before conception, and 64.5% (109/169) of women from rural areas failed to take FA before pregnancy. Women living in northern China (odds ratio [OR] = 1.81, 95% confidence interval [CI], 1.18-2.77), those with unplanned pregnancy (OR = 1.99, 95% CI 1.30-3.04), and highly educated women (OR = 2.37, 95% CI 1.45-3.88) were more likely to know about FA. Women who were homemakers (OR = 1.94, 95% CI 1.21-3.11) and had unplanned pregnancy (OR = 6.18, 95% CI 4.01-9.53) were less likely to begin taking FA before pregnancy. CONCLUSIONS: Our survey showed that most pregnant women knew about FA. Although preconception intake of FA can help to reduce NTDs, improving the rate of FA intake before pregnancy is needed in urban areas of China, especially among homemakers and women from rural areas or with unplanned pregnancy. Campaigns are needed to increase awareness about FA and FA use before pregnancy among rural women, homemakers, and those with unplanned pregnancy and lower education levels.

Computational materials discovery: the case of the W-B system.

By means of variable-compositional evolutionary algorithms, in combination with first-principles calculations, the compositions, structures and mechanical properties of the W-B system have been theoretically investigated. As well as confirming the experimental observations (including their crystal structures) for the four known compounds W2B, WB, WB2 and WB3, the new stable compound W8B7 and two nearly stable compounds, W2B3 and WB4, have also been predicted in the ground state. The elastic properties and estimated Vickers hardnesses of all these borides have been systematically derived. The results show that, among these borides, hP6-WB2 exhibits the largest ultra-incompressibility along the c axis, with the highest C33 value (953 GPa, comparable with that of the most incompressible diamond). hP16-WB3 exhibits the highest hardness of 36.9 GPa, in good agreement with the experimentally measured data from 28.1 to 43.3 GPa, close to the superhard threshold, and oC8-WB shows the highest bulk modulus of about 350 GPa. The new stable compound W8B7 crystallizes in the monoclinic mP15 phase, with infinite zigzag B chains running parallel to the W-atom layers, resulting in a relatively high estimated hardness of 19.6 GPa. The anisotropic Young's modulus E and torsion shear modulus G(t) have been derived for both oC8-WB and hP16-WB3. The current state of research and the historic inconsistency of the W-B system are briefly summarized, in particular clarifying the fact that the previous experimentally attributed hP20-WB4 is in fact the defect-containing hP16-WB3.