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The growth process is crucial to achieve large-sized and high-quality aluminum nitride (AlN) crystals through the physical vapor transport (PVT) method. To investigate the influence of parameters on the growth of AlN crystals, a series of quasi-steady numerical simulations on the temperature distribution, growth rate, and partial pressure of Al vapor inside the growth cell were conducted based on a self-developed finite element mass transfer module in the COMSOL package, which considers the partial pressure of gas phases, for different growth temperatures and crucible positions. The simulation results show that increasing the growth temperature significantly augments the partial pressure of Al vapor and the growth rate in the growth cell. Simultaneously, variation of the crucible position substantially alters the temperature distribution and the transport direction of Al vapor inside the crucible. A novel heat sink on the top of the crucible was designed to impair the phenomenon of uneven crystal growth on the surface of the seed caused by the nonuniform radial temperature distribution. Compared to the original crucible, the radial temperature gradient of the optimized crucible was reduced by 37%, and the uniformity of seed surface growth was improved by 89%. This work guides the design of a novel crystal growth furnace and the preparation of high-quality AlN single crystals by the PVT method. [ABSTRACT FROM AUTHOR]

OBJECTIVE: Cold exposure (CE) before birth is one of the initial stressors that may impact mammalian pregnancy, changing placental and fetal development and affecting the health of the offspring. While glucocorticoids (GCs) participate in the body’s response to the stress of CE, the specific mechanisms of their action are unclear. This study aims to determine the effect of CE stress on the placenta and to test whether stress, caused by cold exposure in pregnancy impairs fetal development by changing placental angiogenesis via excessive GC expression. MATERIALS AND METHODS: CE rat model was created by exposing 30 SD rats to cold preconception, or during the first, second, and third weeks of pregnancy. Serum cortisol and soluble fms-like tyrosine kinase-1 (sFlt-1) expression levels, physiological index changes (food intake, body weight change and blood pressure), and pregnancy outcomes (fetal rat weight, number of live fetal rats, and placental weight) were collected at baseline and at different time points after the conception. Protein expression levels of 11 β-hydroxysteroid dehydrogenase 2 (11β-HSD2), glucocorticoid receptor, vascular endothelial growth factor A (VEGF-A), placental growth factor (PIGF), and sFlt-1 in placental tissues were measured by western blotting. Cytokeratin (CK) and laminin (LN) in trophoblasts, and α-actin in vascular smooth muscle of the spiral arteries of pregnant rats after the systemic cold treatment were assessed by immunofluorescence and visualized by fluorescent microscopy. To test the effect of 11β-HSD2 levels on the placental recasting, human first-trimester extravillous trophoblast cells (HTR8/SVneo) underwent knockdown using specific 11β-HSD2 siRNA constructs. Expression levels of 11β-HSD2 were analyzed by quantitative real-time PCR (qPCR) and into HTR8 cells, and the expression levels of the 11β-HSD2 gene in each group were measured using qPCR. Cell migration and invasion was assessed by Transwell migration assay, and sFlt-1 levels in HTR8 cells were measured by ELISA.RESULTS: CE pre-conception led to consistently increasing serum corticosterone and sFlt-1 levels throughout pregnancy, and persistently increased diastolic blood pressure (DBP) in rat CE model compared to control animals. CE during the second week of gestation (Gp.3) was associated with significantly lower placental weight (p=0.0003). Cold exposure in the third week (Gp.4) was associated with significantly (p=0.001) lower fetal weight. CE pre-conception was associated with significantly decreased placental levels of 11β-HSD2, glucocorticoid receptor, VEGF-A, PIGF, and sFlt-1 proteins and α-actin compared to the control group. Silencing 11β-HSD2 by siRNA led to reduced cell migrations and invasion, and markedly increased expression levels of sFlt-1 in HTR8/SVneo cells (p<0.05). CONCLUSIONS: Pre-conception cold exposure and during early pregnancy leads to increased GCs levels and impaired placental 11β-HSD2 activity. We suggest that the subsequent 11β-HSD2-induced increase in the sFlt-1expression during early pregnancy may affect placental vascular remodeling and change placental morphological structure and function. [ABSTRACT FROM AUTHOR]

OBJECTIVE: Growing evidence shows that pulse pressure (PP) is a strong risk factor for cardiovascular disease and is closely associated with cardiovascular events, strokes, and mortality. However, currently, data on the relationship between body mass index (BMI) and PP are still limited. SUBJECTS AND METHODS: Here, a cross-sectional study was conducted based on 211,809 non-diabetic adults in 11 cities in China from 2010 to 2016. Raw data were obtained from a public database (www.datadryad.org). According to the BMI level, they are classified into "underweight", "normal", "overweight", and "obesity" groups. Two groups of continuous variables were measured by the Mann-Whitney test, while the differences between multiple groups were tested by Kruskal-Wallis' One-Way ANOVA and Dunn's test. Besides, multiple linear regression analyses were performed to assess the linear relationship between BMI and PP. In addition, multivariate logistic regression was carried out to further confirm the relationship between different BMI levels and the prevalence of high PP. RESULTS: In the total population, BMI was linearly positively related to PP regardless of gender and age, but it was not observed in the elevated blood pressure group. Multiple linear regression analysis showed that after fully adjusting for the maximum covariates, compared to the normal group, PP in the overall population decreased by 2.19 mmHg in the underweight group and increased by 1.426 and 2.919 mmHg in the overweight and obese groups, respectively. Similar results were observed in men, women, age <60 years, and normotensive groups. However, there was no significantly linear relationship between BMI and PP at the age of ≥60 years and elevated blood pressure groups. Besides, from multiple logistic regression analysis, the similar results were obtained, with no obvious association between BMI and high PP prevalence in those aged ≥60 years or with elevated blood pressure. CONCLUSIONS: PP increased with rising BMI in the overall population. However, strati- fied analysis demonstrated no significant association between BMI and PP in individuals aged over 60 years or with elevated blood pressure. [ABSTRACT FROM AUTHOR]

OBJECTIVE: The aim of the study was to investigate the effect of induction of labor on maternal and fetal outcomes. PATIENTS AND METHODS: This retrospective case-control study included 4386 pregnant women with low-risk singleton pregnancies who underwent regular prenatal examination and successful vaginal delivery at =41 weeks and 0 days of gestation in Fujian Maternal and Child Health Hospital between January 2014 and December 2018. Clinical data of women were retrospectively divided into the induction of labor group (2007 cases) and spontaneous onset of labor group (2361 cases) based on the mode of labor initiation. Two-sample independent t-test and X2 tests were used to analyze the differences in clinical characteristics, such as maternal age and parity between the two groups. RESULTS: The induction of the labor group had a significantly longer total duration of labor (9.37±5.37 vs. 8.82±5.13 h; p<0.001), more postpartum blood loss (219.18±188.32 vs. 199.95±124.69 mL; p=0.01) and a significantly higher incidence of severe postpartum hemorrhage (PPH) comparing to the spontaneous onset of labor group [0.8% (16/2007) vs. 0.33% (8/2361); p=0.041]. However, no significant difference was found in the neonatal outcomes. After adjusting for age, induction of labor in nulliparous women was more likely to lead to PPH than the spontaneous onset of labor [2.74% (55/2007) vs. 1.65% (39/2361); odds ratio=1.557; 95% confidence interval: 1.039-2.332; p<0.05]. CONCLUSIONS: Induction of labor increases the duration of labor and postpartum blood loss, especially in primary parturient, leading to an increased risk of PPH. This increase may be related to the overall higher duration of labor, associated with IOL. Therefore, low-risk nulliparous women should try to avoid induction of labor without medical indications. [ABSTRACT FROM AUTHOR]

ToTEM, a multislice‐based image simulation software is developed for transmission electron microscope (TEM). This software implements the following major features: (i) capability of assigning three‐dimensional potentials of atom into multiple slices and precise introduction of phase shift caused by the sub‐pixel atomic position, (ii) employing CUDA coding and graphical processing units (GPU) with multithreading parallel algorithm based on the powerful batch (inverse) fast Fourier transform (FFT), which is especially beneficial for image simulation of scanning transmission electron microscopy (STEM) or (integrated) differential phase contrast (I)DPC, (iii) design for efficiently generating large batch of data set of high‐resolution transmission electron microscopy (HRTEM) images. Image simulation acceleration for STEM has been verified by simulating a large‐scale SrTiO3. Additionally, iDPC image of MFI‐type zeolites with xylene molecules encapsulated in straight channels demonstrates the advantage of iDPC in detecting light molecules. [ABSTRACT FROM AUTHOR]