Study of Sintering Behavior of Methane Hydrate Particles on the Wall Surface.

The sintering of hydrate aggregates on the pipe wall is a major form of hydrate deposition. Understanding the sintering behavior of hydrates on the wall is crucial for promoting hydrate safety management and preventing pipeline blockage. However, limited research currently exists on this topic. In this study, the cohesive force strength of hydrate particles on the wall surface under different conditions was directly measured using a high-pressure micromechanical force device (HP-MMF). Subsequently, the effects of subcooling and glycine on the cohesive force were investigated. The results indicate that the cohesive force is influenced by different growth states during the process of free water on the wall surface gradually growing into hydrate. Three states with larger measured values during the growth process were selected for research. Observation showed that increased subcooling strengthened sintering by accelerating the growth rate of the hydrate film, resulting in a significant increase in cohesive force. The role of glycine in the methane hydrate system was then evaluated. Glycine was found to reduce the degree of sintering by reducing the growth rate of the hydrate film, thereby decreasing the cohesive force. The optimal concentration in the system was determined to be 0.25 wt %. Moreover, compared with low subcooling (1 °C), glycine had a better effect at high subcooling (5 °C). At 5 °C subcooling and the optimal concentration, the cohesive force in the wall droplet state decreases from 677.38 to 489.02 mN/m, the cohesive force at the low-saturation state decreases from 951.79 to 543.32 mN/m, and the cohesive force at the high-saturation state decreases from 1194.95 to 641.76 mN/m. These findings contribute to a better understanding of the cohesive force behavior of gas hydrate on the inner wall of the pipeline and provide basic data for reducing the risk of hydrate blockage.

[Genetic analysis of the UGT1A1 gene mutation sites in a Chinese family suffered from Gilbert's syndrome].

To learn the variation in the gene for UGT1A1 enzyme, the genetic mechanism in a Chinese Han nationality family suffered from Gilbert's syndrome was studied. At first, genomic DNA from peripheral blood of the sufferer in this family was used for amplifying all of the five exons of the UGT1A1 gene by PCR, and then direct sequencing of the PCR product was applied to analyze gene mutation. The results showed that there existed a G-->A homozygous transition at nucleotide 211 leading the substitution of arginine for glycine at position 71 of corresponding protein product (G71R) and a T-->G homozygous transition at nucleotide 1456 leading the substitution of aspartic acid for tyrosine at position 486 of corresponding protein product (Y486D). No mutation was detected in promoter region and the splicing junction sites. The relevant mutation sites of the other family members were sequenced and identified to be heterozygous in the two above-mentioned mutation sites and in the TA repeat mutation in the promoter region. Furthermore, fresh blood samples were collected from all of the members to detect the serum bilirubin levels to determine the sufferer. The result was consistent with the mutation analysis. It could thus be inferred that this family was caused by mutation in the open reading frame of the gene UGT1A1.

[Concentrations of cortisol and dehydroepiandrosterone sulfate in fetal umbilical cord blood for term labor].

OBJECTIVE: To study the effect of cortisol and dehydroepiandrosterone sulfate (DHEA-S) in fetal umbilical cord blood on term labor. METHODS: Cortisol and DHEA-S concentrations were measured By radioimmunoassay in 100 term fetal umbilical cord blood. They were divided into four groups. Group A selective cesarean section without any birth pain (n = 18), Group B cesarean section in latent phase (n = 10), Group C cesarean section in active phase (n = 12), Group D spontaneous vaginal deliver (n = 60). RESULTS: The concentrations of fetal umbilical cord cortisol in spontaneous vaginal deliver group was gradually increased with gestational week. The peak level was in the 39th gestation week, by the 42nd gestation week, the concentration of cortisol declined to the 37th gestation week. DHEA-S changed paralleled with cortisol (r = 0.46, P < 0.05). Active birth pain was associated with increased fetal umbilical cortisol concentration, but not with DHEA-S. The concentrations of fetal umbilical cord cortisol in vaginal deliver group was higher than all the cesarean section groups. CONCLUSION: Concentrations of cortisol and DHEA-S played an important role in the initiation and acceleration of labor.