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Objective: To investigate cumulative live birth rate (cLBR) per oocyte retrieval in infertile patients aged 40 years and over undergoing their first in vitro fertilization/intracytoplasmic sperm injection cycles and to identify the possible predictors. Methods: A total of 1,613 patients at a university hospital in China from January 2013 to May 2017 were enrolled in this retrospective study. All data for fresh and subsequent frozen-thawed cycles were analyzed. Multivariate logistic regression analysis with stepwise selection of possible predictors for cLBR was performed, and Loess curve was constructed to determine the association between cLBR and the number of oocytes retrieved. Results: cLBR significantly increased with the number of oocytes retrieved and reached up to 75% when > 20 oocytes were retrieved ( P < 0.001). Variables of antral follicle count (AFC) and the number of oocytes retrieved were selected using multiple logistic regression analysis with stepwise selection to predict the significance of cLBR. cLBR demonstrated an obvious upward trend as the number of oocytes retrieval increased in the Loess curve. Conclusions: For patients aged 40 years and over, AFC and the number of oocytes retrieved were two key predictors for cLBR and maximization of ovarian reserve exploitation was pivotal to increase the chance of live birth.

CO2 dry fracturing is a promising alternative method to water fracturing in tight gas reservoirs, especially in water-scarce areas such as the Loess Plateau. The CO2 flowback efficiency is a critical factor that affects the final gas production effect. However, there have been few studies focusing on the flowback characteristics after CO2 dry fracturing. In this study, an extensive core-to-field scale study was conducted to investigate CO2 flowback characteristics and CH4 production behavior. Firstly, to investigate the impact of core properties and production conditions on CO2 flowback, a series of laboratory experiments at the core scale were conducted. Then, the key factors affecting the flowback were analyzed using the grey correlation method based on field data. Finally, taking the construction parameters of Well S60 as an example, a dual-permeability model was used to characterize the different seepage fields in the matrix and fracture for tight gas reservoirs. The production parameters after CO2 dry fracturing were then optimized. Experimental results demonstrate that CO2 dry fracturing is more effective than slickwater fracturing, with a 9.2% increase in CH4 recovery. The increase in core permeability plays a positive role in improving CH4 production and CO2 flowback. The soaking process is mainly affected by CO2 diffusion, and the soaking time should be controlled within 12 h. Increasing the flowback pressure gradient results in a significant increase in both CH4 recovery and CO2 flowback efficiency. While, an increase in CO2 injection is not conducive to CH4 production and CO2 flowback. Based on the experimental and field data, the important factors affecting flowback and production were comprehensively and effectively discussed. The results show that permeability is the most important factor, followed by porosity and effective thickness. Considering flowback efficiency and the influence of proppant reflux, the injection volume should be the minimum volume that meets the requirements for generating fractures. The soaking time should be short which is 1 day in this study, and the optimal bottom hole flowback pressure should be set at 10 MPa. This study aims to improve the understanding of CO2 dry fracturing in tight gas reservoirs and provide valuable insights for optimizing the process parameters. [ABSTRACT FROM AUTHOR]

Under the hydrothermal method, a Pb(II) coordination polymer [Pb(ox)(phen)2]·5H2O 1 (ox = oxalate, phen = 1,10-phenanthroline) was obtained. Ox ligands exhibit a μ2-coordination mode, which connect Pb2+ centers into a 1-D single-chain with ancillary phen molecules. Interestingly, adjacent phen molecules between the chains exist π…π stacking interaction, which extend the 1-D chain into a 2-D supramolecular layer. Compound 1 showed outstanding photocatalytic performance and the degradation efficiency of methylene blue with H2O2 could reach 95.69% under the irradiation of visible light at pH = 10. In addition, 5 cycles of degradation experiments were also carried out, and it was found that the degradation efficiency values with and without H2O2 were reduced by 1.46% and 1.08%, respectively. It was also discussed that which free radical played the dominant role in the photocatalytic process. What’s more, we speculated the possible reaction mechanism based on the Mott–Schottky curve. Meanwhile, the UV visible diffuse reflection of compound 1 was also investigated. [ABSTRACT FROM AUTHOR]

Anovel support vector regression (SVR) optimized by an improved particle swarm optimization (PSO) combined with simulated annealing algorithm (SA) was proposed. The optimization mechanism also combined the discrete PSO with the continuous-valued PSO to simultaneously optimize the input feature subset selection and the SVR kernel parameter setting. By incorporating with SA, the global searching capacity of the proposed model was enhanced. The improved SAPSO was used to optimize the parameters of SVR and select the input features simultaneously. Based on the operational data provided by a regional power grid in north China, the method was used in short-term load forecasting (STLF). The experimental results showed the proposed approach can correctly select the discriminating input features and compared to the PSO-SVR and the traditional SVR, the average time of the proposed method in the experimental process reduced and the forecasting accuracy increased respectively. So, the improved method is better than the other two models. [ABSTRACT FROM AUTHOR]

We investigate the above-threshold ionization of an atom in a combined infrared (IR) and extreme ultraviolet (XUV) two-color laser field and focus on the role of XUV field in the high-order above-threshold ionization (HATI) process. It is demonstrated that, in stark contrast to previous studies, the XUV laser may play a significant role in atomic HATI process, and in particular, the XUV laser can accelerate the ionized electron in a quantized way during the collision between the electron and its parent ion. This process cannot be explained by the classical three-step model. Our results indicate that the previously well-established concept that HATI is an elastic recollision process is broken down. [ABSTRACT FROM AUTHOR]