Incidence of Down Syndrome by maternal age in Chinese population.

Objective: This study aims to estimate the maternal age-related risk of Down syndrome in an Asian population. Methods: We performed a retrospective data analysis including a total of 206,295 pregnant women who presented for second-trimester maternal serum screening for Down syndrome at Hubei Maternal and Child Health Hospital for the years 2008-2017. Cases were assigned to three groups: ≤26 years of age, 27-33 years of age, and ≥34 years of age. The incidence of Down Syndrome was calculated for each age group. The differences between groups were tested using the chi-square (χ2) test. Results: The incidence of Down syndrome in women ≤26 years of age, 27-33 years of age, and ≥34 years of age was 0.67‰, 0.29‰, and 2.07‰ respectively. Statistically significant difference was found between the three age groups (χ2 = 79.748, p < 0.05). Conclusion: Down syndrome rate was significantly higher in women ≥34 years of age. Younger women (≤26 years of age) had a significantly higher risk for Down's syndrome, compared to women aged 27-33.

Genome-wide identification and expression characterization of the DoG gene family of moso bamboo (Phyllostachys edulis).

BACKGROUND: The DoG (Delay of Germination1) family plays a key regulatory role in seed dormancy and germination. However, to date, there is no complete genomic overview of the DoG gene family of any economically valuable crop, including moso bamboo (Phyllostachys edulis), and no studies have been conducted to characterize its expression profile. To identify the DoG gene members of moso bamboo (PeDoG) and to investigate their family structural features and tissue expression profile characteristics, a study was conducted. Based on the whole genome and differential transcriptome data, in this investigation, we have scrutinized the physicochemical properties, gene structure, cis-acting elements, phylogenetic relationships, conserved structural (CS) domains, CS motifs and expression patterns of the PeDoG1 family of moso bamboo. RESULTS: The DoG family genes of moso bamboo were found distributed across 16 chromosomal scaffolds with 24 members. All members were found to carry DoG1 structural domains, while 23 members additionally possessed basic leucine zipper (bZIP) structural domains. We could divide the PeDoG genes into three subfamilies based on phylogenetic relationships. Covariance analysis revealed that tandem duplication was the main driver of amplification of the PeDoG genes. The upstream promoter of these genes containing several cis-acting elements indicates a plausible role in abiotic stress and hormone induction. Gene expression pattern according to transcriptome data revealed participation of the PeDoG genes in tissue and organ development. Analysis using Short Time-series Expression Miner (STEM) tool revealed that the PeDoG gene family is also associated with rapid early shoot growth. Gene ontology (GO) and KEGG analyses showed a dual role of the PeDoG genes. We found that PeDoGs has a possible role as bZIP transcription factors by regulating Polar like1 (PL1) gene expression, and thereby playing a disease response role in moso bamboo. Quantitative gene expression of the PeDoG genes revealed that they were abundantly expressed in roots and leaves, and could be induced in response to gibberellin (GA). CONCLUSION: In this study, we found that the PeDoG genes are involved in a wide range of activities such as growth and development, stress response and transcription. This forms the first report of PeDoG genes and their potential roles in moso bamboo.

Acceleration-Level Cyclic-Motion Generation of Constrained Redundant Robots Tracking Different Paths.

In this paper, a cyclic-motion generation (CMG) scheme at the acceleration level is proposed to remedy the joint-angle drift phenomenon of redundant robot manipulators which are controlled at the joint-acceleration level or torque level. To achieve this, a cyclic-motion criterion at the joint-acceleration level is exploited. This criterion, together with the joint-angle limits, joint-velocity limits, and joint-acceleration limits, is considered into the scheme formulation. In addition, the neural-dynamic method of Zhang is employed to explain and analyze the effectiveness of the proposed criterion. Then, the scheme is reformulated as a quadratic program, which is solved by a primal-dual neural network. Furthermore, four tracking path simulations verify the effectiveness and accuracy of the proposed acceleration-level CMG scheme. Moreover, the comparisons between the proposed acceleration-level CMG scheme and the velocity-level scheme demonstrate that the former is safer and more applicable. The experiment on a physical robot system further verifies the physical realizability of the proposed acceleration-level CMG scheme.

Fabrication of polycrystalline tubular ZnO via a modified ultrasonically assisted two-step polyol process and characterization of the nanotubes.

An ultrasonically assisted two-step polyol process was established to fabricate polycrystalline ZnO nanotubes. Thus one-dimensional (1D) precursors were prepared from an ethylene glycol (EG) solution containing 0.3 M of zinc acetate in the presence of ultrasonic irradiation. The ZnO nanotubes were obtained by calcination of the precursors at proper temperatures. The precursors and polycrystalline ZnO nanotubes obtained at various calcination temperatures were characterized by means of scanning electron microscopy (SEM), Fourier transformation infrared spectrometry (FTIR), x-ray diffraction (XRD, together with temperature-resolved XRD), and transmission electron microscopy (TEM). It was found that the precursors were extremely sensitive to atmospheric moisture and instantly transformed to layered hydroxide zinc acetate (LHS-Zn) after being exposed to air, accompanied by the erosion and deformation of the one-dimensional structure. After being calcined at proper temperatures, the precursors were completely transformed into polycrystalline tubular ZnO, and the sizes of the resulting ZnO nanocrystallites increased with increasing calcination temperature, implying that polycrystalline tubular ZnO of desired sizes could be fabricated using the present method by properly controlling the calcination temperature. However, the tubular structures were destroyed at a calcination temperature of 400 °C and above, owing to the growth of polycrystalline ZnO. Moreover, the present method could be used to synthesize other tubular metal oxides, and tubular ZnO might find promising applications in gas-sensitive sensors and catalysis as well.