Rapid Growth of the CO2 Hydrate Induced by Mixing Trace Tetrafluoroethane.

Rapid formation of the CO2 hydrate can be significantly induced by the gaseous thermodynamic promoter 1,1,1,2-tetrafluoroethane(R134a) due to the mild phase equilibrium conditions, although the formation mechanism and dynamic behavior are not clear. Therefore, a visual experimental system was developed to study the effects of different concentrations of R134a on the induction time, gas consumption, and growth morphology of the CO2 hydrate. At the same time, the combined effects under stirring and sodium dodecyl sulfate (SDS) systems were also studied. In addition, visualization and experimental model diagrams were combined to explain the fast formation mechanism of the R134a/CO2 hydrate. The results show that the CO2 hydrate average conversion rate was increased by more than 63% with the addition of mixed trace R134a(7%). A special phenomenon is found that two temperature peaks appear on the hydrate formation temperature curve, corresponding to two different stages of hydrate formation when stirring or SDS is added to the mixed gas reaction system. Furthermore, the gas consumption in stirring and SDS systems increases by 9 and 44%, respectively. Finally, it is also found that the R134a/CO2 mixed hydrate formed under the action of SDS has a "capillary" mechanism, which provides a gas-liquid phase exchange channel and a large number of nucleation sites for CO2 hydrate, thus promoting the formation of CO2 hydrate. This paper provides a novel, simple, and efficient method for CO2 hydrate gas storage technology.

Topologically inferring pathway activity for precise survival outcome prediction: breast cancer as a case.

Accurately predicting the survival outcome of patients is of great importance in clinical cancer research. In the past decade, building survival prediction models based on gene expression data has received increasing interest. However, the existing methods are mainly based on individual gene signatures, which are known to have limited prediction accuracy on independent datasets and unclear biological relevance. Here, we propose a novel pathway-based survival prediction method called DRWPSurv in order to accurately predict survival outcome. DRWPSurv integrates gene expression profiles and prior gene interaction information to topologically infer survival associated pathway activities, and uses the pathway activities as features to construct Lasso-Cox model. It uses topological importance of genes evaluated by directed random walk to enhance the robustness of pathway activities and thereby improve the predictive performance. We applied DRWPSurv on three independent breast cancer datasets and compared the predictive performance with a traditional gene-based method and four pathway-based methods. Results showed that pathway-based methods obtained comparable or better predictive performance than the gene-based method, whereas DRWPSurv could predict survival outcome with better accuracy and robustness among the pathway-based methods. In addition, the risk pathways identified by DRWPSurv provide biologically informative models for breast cancer prognosis and treatment.

[Clinical outcomes of twin pregnancies conceived by in vitro fertilization compared with spontaneous twin pregnancies].

OBJECTIVE: To compare the maternal and perinatal outcomes of twin pregnancies conceived by in vitro fertilization (IVF) with outcomes of spontaneous twin pregnancies. METHODS: A retrospective analysis was conducted between January 2010 and April 2014 to investigate the maternal age, gestation length, modes of delivery, pregnancy complications and neonatal physical development, birth defects and perinatal diseases in 106 IVF-assisted twin pregnancies (IVF group) and 256 spontaneous twin pregnancies (control group). RESULTS: The mothers in the IVF group were significantly older than those in the control group (32±4 years vs 28±4 years, P<0.05). The incidence rates of gestational hypertension and gestational diabetes in the IVF group were significantly higher than in the control group (P<0.05). No significant differences were observed for neonatal physical development, the incidence of birth defects, and the incidence and mortality of perinatal diseases (P>0.05). CONCLUSIONS: Twins conceived by IVF have similar outcomes as spontaneously conceived twins in the perinatal period. However, special attention is needed to monitor the levels of blood pressure and blood glucose for pregnant women with twins conceived by IVF during prenatal checkups.