Modulating the resistive switching stability of HfO2-based RRAM through Gd doping engineering: DFT+U.

Oxide-based resistive random access memory (RRAM) is standing out in both non-volatile memory and the emerging field of neuromorphic computing, with the consequence of increasing performance demands. Rare-earth doping is often used as an effective means for performance modulation. In this work, the modulation mechanism of the resistive switching (RS) behaviors in trivalent rare-earth Gd-doped HfO2-based RRAM has been carefully investigated using first-principles calculations. The results of electronic structure analysis show that Gd doping would lead to a change in the local geometry of the m-HfO2 defect system and would enhance the Coulomb interaction between the atoms around Gd and oxygen vacancy (VO), which may be one of the reasons for the enhanced conductivity of the HfO2-based RRAM after Gd doping. Thermodynamic and kinetic study results indicate that there is a strong interaction between Gd and its surrounding VO defects, and this strong interaction would not only attract more oxygen vacancies (VOs) to be generated near the dopant Gd, but also increase the migration energy barrier of the +2 charged VOs around the Gd doping site, thus suppressing the random generation of VO filaments, which leads to a better uniformity of the switching parameters during the RS process and improves the performance stability of the devices. The results of this work will provide new insights into modulating the RS behaviors and improving the device performance of HfO2-based RRAM through doping engineering.

The association between serum folate and gestational diabetes mellitus: a large retrospective cohort study in Chinese population.

OBJECTIVE: To investigate the association between folate levels and the risk of gestational diabetes mellitus (GDM) risk during the whole pregnancy. DESIGN: In this retrospective cohort study of pregnant women, serum folate levels were measured before 24 gestational weeks (GW). GDM was diagnosed between 24th and 28th GW based on the criteria of the International Association of Diabetes and Pregnancy Study Groups. General linear models were performed to examine the association of serum folate with plasma glucose (i.e. linear regressions) and risk of GDM (i.e. log-binomial regressions) after controlling for confounders. Restricted cubic spline regression was conducted to test the dosage-response relationship between serum folate and the risk of GDM. SETTING: A sigle, urban hospital in Shanghai, China. PARTICIPANTS: A total of 42 478 women who received antenatal care from April 2013 to March 2017 were included. RESULTS: Consistent positive associations were observed between serum folate and plasma glucose levels (fasting, 1-h, 2-h). The adjusted relative risks (RR) and 95 % CI of GDM across serum folate quartiles were 1·00 (reference), 1·15 (95 % CI (1·04, 1·26)), 1·40 (95 % CI (1·27, 1·54)) and 1·54 (95 % CI (1·40, 1·69)), respectively (P-for-trend < 0·001). The positive association between serum folate and GDM remained when stratified by vitamin B12 (adequate v. deficient groups) and the GW of serum folate measurement (≤13 GW v. >13 GWs). CONCLUSIONS: The findings of this study may provide important evidence for the public health and clinical guidelines of pregnancy folate supplementation in terms of GDM prevention.

Prenatal exposure to fine particulate matter and fetal growth: a cohort study from a velocity perspective.

BACKGROUND: Reduced growth velocity before birth increases the risk of adverse health outcomes in adult life. However, until recently, there has been a lack of studies demonstrating the impact of prenatal PM2.5 exposure on fetal growth velocity. METHODS: The current study was embedded in a previous cohort built between January 1, 2014, and April 30, 2015, in Shanghai First Maternity and Infant Hospital, China, in 6129 eligible singleton pregnancies. The PM2.5 concentration was estimated by an inverse distance weighted method according to the residential addresses of the participants. Repeated fetal biometry measurements, including head circumference (HC), abdominal circumference (AC), femur length (FL), and biparietal diameter (BPD), were measured through ultrasound between 14 and 41 gestational weeks. A principal component analysis through conditional expectation for sparse longitudinal data was used to estimate the corresponding velocities. RESULTS: A total of 22782 ultrasound measurements were conducted among 6129 participants with a median of 2 and a maximum of 9 measurements. With each 10 µg/m3 increase in cumulative PM2.5 exposure, the velocity of HC, AC FL and BPD decreased by 0.12 mm/week, 0.17 mm/week, 0.02 mm/week and 0.02 mm/week, respectively, on average. The results of the Generalized Functional Concurrent Model showed that the velocity decreased significantly with PM2.5 exposure between 22 and 32 gestational weeks, which might be the potential sensitive exposure window. CONCLUSIONS: There are negative associations between prenatal exposure to PM2.5 and fetal growth velocity, and the late second trimester and early third trimester might be the potential sensitive window.

Satisfaction of village doctors with the township and village health services integration policy in the western minority-inhabited areas of China.

Township and Village Health Services Integration Management (TVHSIM) is an essential form of China's two-tiered health service integration plan at the township and village level. Its main purpose, also one of the target goals in China's new healthcare reform, is to gradually integrate rural health services and appropriately allocate rural health resources. This study aims to assess the village doctors' satisfaction with the TVHSIM and provide scientific base to further improve TVHSIM. A cross-sectional study was carried out in which 162 village doctors from Qinghai, Inner Mongolia and Xinjiang in western China were interviewed. Descriptive analysis, independent t-test, one-way ANOVA, Spearman rank correlation and multiple linear regression were used to analyze the difference and relevance between village doctors' personal characteristics and their satisfaction with TVHSIM and six subscales. Village doctors with different years of practice, social insurance status and essential medical knowledge level showed statistically significant differences in their satisfaction levels (all P<0.05). Age (P<0.05) and years of practice (P<0.01) were negatively correlated with Drug and Medical Device Management and Financing Management. Essential medical knowledge level (P<0.05) was negatively correlated with Operations Management as well. However, social insurance status (P<0.05) was positively correlated with Human Resources Management and Drug and Medical Device management. Gender, age and years of practice respectively had significant influence on village doctors' satisfaction with TVHSIM (P<0.01). In conclusion, in order to further promote TVHSIM policy in rural China, a well-rounded social insurance model for village doctors is urgently needed. In addition, the development of TVHSIM is regionally imbalanced. Efficient and effective measures aiming at rationalizing gender and age structure and enhancing essential medical training should be carefully considered.