Objective : To characterize the metabolic variation in neonatal hair samples associated with intrauterine growth discordance in dichorionic-diamniotic (DCDA) twins and to evaluate the effects of specific metabolic alterations on later neurobehavioural outcomes in infancy. Design: Cohort-based case-control study Setting: Peking University Third Hospital Population: DCDA twins with birth weight discordance(DCDA-D) and birthweight concordance (DCDA-C) within a twin cohort recruited between September 2017 and December 2018 in Beijing, China. Methods: A specific hair metabolic profile of 14 pairs of DCDA-D twins was revealed using gas chromatography-mass spectrometry by comparing that of 28 pairs of DCDA-C twins. Pearson’s correlation was used to assess the relationship between the neonatal hair metabolome and neurocognitive outcomes, assessed using the Ages and the Infant’s Stages Questionnaires, third edition (ASQ-3) at 2 or 3 years of age. Main outcome measure: neonatal hair metabolome and long-term neurodevelopment. Results: A total of seventeen hair metabolites were significantly different within DCDA-D twin pairs compared to DCDA-C twins. Particularly, reduced levels of cysteine, threonine, and leucine were identified in both the larger and smaller DCDA-D twins compared with DCDA-C twins. The deregulated metabolic pathways including cysteine, methionine, aminoacyl-tRNA, nicotinate, and nicotinamide metabolism biosynthesis pathways in DCDA-D groups were positively correlated with infant neurocognitive development at 2 or 3 years of age, especially in problem-solving domains. Conclusion: Neonatal hair metabolic variations in utero of growth discordance in DCDA twins may be associated with poor neurocognitive development. Metabolome profiles of hair may be novel predictors of infant neurodevelopment longitudinally.
The paper has analyzed uses the light single wobbling pole caving supports in longwall top-coal caving mining by the large-scale finite element software ANSYS.According to the stress of the support and distribution situation of variation in shape,the paper has drawn some beneficial conclusions.It is much meaning to improve and optimize the type of support and the suited equipments,and increases reliability of caving powered support.
The horizontal section top coal caving in steep seam is different from the gently inclined seam.Following the horizon of the coal seam thicknesst,he working face is arranged with short length.However,no roof but top coal and rock residues is found above the working face.The study shows that arch structure of spanning strata which parallels to its spanning coal seam,is formed above the working face in mining.The mechanical model of arch of spanning strata is established;and the inner forces calculation of arch,establishment of maximal arch span and arch shape are analyzed.The instability of arch of spanning strata can be cataloged as sliding instability and structure instability.The influence of instability on strata behavior of working face is analyzed and tested by field experiments.It shows that the analytical results of the proposed mechanical model agree well with those of in-situ tests measurement.The results indicate that the height of horizontal subsection can be increased.It is much meaningful to effectively control strata and to realize high yield and high efficiency for mining in the condition of short working face in steep seam.
According to the characters of hard-thick coal seam in Xiagou mine,a test was carried out to analyse the technique of the directional hole-forming and the projectile filling in long-borehole of the top-coal,which provides the technical support for the top-coal avianize.The technique has the generalization and application value for top-coal avianize under the same geological conditions.
The hydraulic system pollution sources and hazards are analyzed.The hydraulic system oil pollution control methods are analyzed by mainly the oil basin's design.Other components of the drilling rig pollution control and pollution control using the stage to make targeted improvements are presented.The cleanliness of the hydraulic system and the reliability of tunnel drilling rig are improved.It is useful to the design of the hydraulic contamination control system engineering machine.
To study the tensile stress-strain relation and the failure mechanism of two stainless steel types (duplex grade S22053 and austenitic grade S30408 stainless steel made in China) and the corresponding weld metals, tensile tests were conducted on four groups of test specimens including three duplicate specimens in each. The fracture micro-mechanism was analyzed by using the scanning electron microscopy (SEM) on the fracture surfaces of the specimens. Based on the experimental stress-strain curves, the parameters of the material constitutive models were obtained by curve-fitting using the modified Ramberg-Osgood equations. Comparisons of the tensile stress-strain relation were made between the base metal and weld metal. The results indicated that both base metal and weld metal fractured in a ductile manner, and their stress-strain relations exhibited significant nonlinearity. Compared with the base metal, the weld metal had a higher yield strength and ultimate tensile strength, but lower ductility. The stress-strain relations of the base metal and the weld metal obtained in the tests can be well fitted by the modified Ramberg-Osgood equations. The differences of stress-strain relation between base metal and weld metal should be taken into consideration, and the corresponding constitutive model should be used separately in the accurate load capacity analysis of welded stainless steel connections.
In order to effectively identify the geological information of the layered formation, the drilling information obtained from the independent drilling test-bed was analyzed and aligned through the information fusion technology, and the heterogeneous data was constructed. The corresponding relationship between the drilling information of the drilling rigs and the layered formation characteristics was established by using data mining method, and the combination of the sensitive drilling parameters was screened. The relationship between various drilling parameters was analyzed by principal component analysis, and the output analysis model of the typical layered formation characteristics was established. The characteristic roots and eigenvectors of each principal component were calculated. The appropriate principal component was selected according to the cumulative contribution rate greater than 90%. The original drilling parameter information could be analyzed by calculating the comprehensive score. The results show that the optimization method is reasonable and feasible, which lays a foundation for the real-time and accurate identification of the characteristics of the coal and rock while drilling.
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