Search

In order to solve the problem that the wellbore liquid loading of low permeability horizontal wells can't be predicted accurately in previous studies, this article establishes a new matrix - natural fracture - wellbore horizontal gas well productivity equation considering stress sensitivity, starting pressure gradient and high speed turbulence effect. The method is used to judge whether there is liquid loading in a gas reservoir, and verified by the critical liquid carrying flow method. The results show that the accuracy rate of predicting liquid loading by productivity equation method is 80%, and the accuracy rate of predicting gas well productivity is 91.55%. Meanwhile, the influence rule of natural fracture parameters on productivity is given and it is found that the stress sensitivity coefficient has little effect on productivity. At the same bottom hole pressure, the gas production gradually decreases with the increase of high-speed nonlinear coefficient and gas production gradually increases with the increase of the number and width of natural fractures. The findings of this study can help for better understanding of the relationship between wellbore liquid loading and gas well productivity, and then better grasping the timing of gas well drainage and gas recovery. [ABSTRACT FROM AUTHOR]

A highly efficient chemoenzymatic approach was developed for the preparative scale synthesis of complex tumor-associated antigen N3 minor octasaccharide. The success of this approach relies on the highly efficient one-pot multi-enzyme based sequential enzymatic elongation of a chemically synthesized branched tetrasaccharide core structure. [ABSTRACT FROM AUTHOR]

It has been 30 years since the discovery of the anti-tumour property of paclitaxel (PTX), which has been successfully applied in clinic for the treatment of carcinomas of the lungs, breast and ovarian. However, PTX is poorly soluble in water and has no targeting and selectivity to tumour tissue. Recent advances in active tumour targeting of PTX delivery vehicles have addressed some of the issues related to lack of solubility in water and non-specific toxicities associated with PTX. These PTX delivery vehicles are designed for active targeting to specific cancer cells by the addition of ligands for recognition by specific receptors/antigens on cancer cells. This article will focus on various ligands and related targeting strategies serving as potential tools for active targeting of PTX to tumour tissues, illustrating their use in different tumour models. This review also highlights the need of further studies on the discovery of receptors in different cells of specific organ and ligands with binding efficiency to these specific receptors. [ABSTRACT FROM AUTHOR]

To improve the ability of superoxide dismutase (SOD) to suppress reactive oxygen species (ROS)-mediated injury, chemically modified derivatives of SOD with N, N, N-trimethyl chitosan chloride (TMC) and heparin, cationized SOD (TMC-SOD), and anionized SOD (heparin-SOD) were designed and prepared. In this study, the inhibitory effect of TMC-SOD and heparin-SOD on superoxide anion release from macrophages was studied in vitro. Both TMC-SOD and heparin-SOD exhibited excellent inhibitory effects on superoxide anion release from macrophages, and the effects of TMC-SOD surpassed those of native SOD and heparin-SOD. The effects of TMC-SOD and heparin-SOD on inflammatory cytokine expression in vitro were also evaluated. The results showed that both TMC-SOD and heparin-SOD could significantly lower the levels of transforming growth factor-β1 (TGF-β1) and interleukine-1β (IL-1β) expressed by irradiated 3T3 fibroblasts. These results demonstrated that cationic polysaccharide or anionic polysaccharide SOD derivatives might be useful in the prevention and treatment of ROS-mediated inflammatory diseases. This study also demonstrated that chemical modification of SOD, especially cationization, greatly enhanced SOD’s intracellular delivery and, consequently, produced a significant protective effect against ROS-mediated injury. [ABSTRACT FROM AUTHOR]