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The enhanced oil recovery (EOR) techniques are employed to recover more oil from mature reservoirs following the primary and secondary stages of oil production. Polymer flooding is a chemical EOR method that involves the addition of polymer molecules to a treated area to improve its water viscosity and sweep efficiency, and to accelerate oil production. The increased water viscosity will reduce the mobility ratio of the injected fluid to the reservoir fluid. Polymer flooding is most effective when applied in the early stages of a water flood while the mobile oil saturation is still high. The polymers used in polymer flooding are divided into synthetic polymers and biopolymers. Unfortunately, synthetic polymers are susceptible to brine formation and high temperatures. On the other hand, biopolymers have a more rigid chemical chain structure making them more resistant to high temperatures (about 135°C) and salinity (about 220 g/L). This review presents a comprehensive discussion of the use of polymers for EOR applications. First, a summary and explanation are given of the structure and characterization of polymers. Subsequently, the general screening criteria for polymer flooding are highlighted. Then, the properties of synthetic and natural polymers and their application in EOR are presented. Finally, the limitations of this study and suggestion for future work on polymers in EOR are explained. [ABSTRACT FROM AUTHOR]

The association between the ABO blood group and the risk of malaria during pregnancy has not been clearly established. The present study summarised relevant knowledge and reassessed the association through meta-analysis. Articles in MEDICINE and PubMed published before 30 November 2021 were searched. Five studies satisfied the inclusion criteria and were enrolled in the meta-analysis. It was shown that primiparae with different ABO blood group, multiparae with blood group A and non-A, AB and non-AB had a comparable risk of malaria. However, multiparae with blood group B had a significantly higher risk than non-B group [odds ratio (OR) = 1.23, 95% confidence interval (CI) was 1.01 to 1.50, P = 0.04], while multiparae with blood group O had a significantly lower risk than non-O group (OR = 0.78, 95% CI was 0.63 to 0.97, P = 0.03). Therefore, the ABO blood group may not result in a different risk of malaria in primiparae. Blood group B is potentially a risk factor while blood group O is a protective factor for multiparae. [ABSTRACT FROM AUTHOR]

The article reviews the book "The Chinese Academy of Social Sciences (CASS): Shaping the Reforms, Academia, and China (1997-2003)," by Margaret Sleeboom-Faulkner.