The differences in teaching chemical experiments of plant fiber resources at home and abroad were introduced.Teaching contents and methods of experiments in China was reformed to strengthen students' understanding of basic theoretical knowledge and mastering of basic experimental skills.Through increasing means of videos in teaching experiments,teachers' demonstrative process would be highlighted and students' practical ability and interest in the experiments were improved.
Methacryloyl chloride was grafted onto lignocresol to increase the acyl content of lignocresol and to enhance the interfacial compatibility of lignocresol and polylactic acid. The physical and mechanical properties of the modified lignocresol sample were studied. The methacryloyl-modified lignocresol was characterized by infrared spectroscopy (IR), ultraviolet-visible (UV) spectroscopy, and gel permeation chromatography (GPC). Unmodified and modified lignocresol samples were used to prepare composite films with polylactic acid, and its tensile strengths and elongations at breaks were analyzed after film formation. Thermal stabilities were evaluated by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The results indicated that methacryloyl group was successfully grafted onto lignocresol, and that the optimum dosage of methacryloyl chloride required was 0.5 mL per 0.5 g of lignocresol. When unmodified lignocresol was added to polylactic acid, the tensile strength gradually decreased as the amount of lignocresol increased. However, the composite films prepared from the methacryloyl-modified lignocresol exhibited a slower decline in tensile strength and displayed an increased elongation at break. The optimum mechanical properties were found using a 10% blend of modified lignocresol with polylactic acid.
Abstract Improving the retention and drainage aid performance of high speed papermaking processes is an important and challenging issue. In this study, fiber modification was used to improve the papermaking retention and drainage aid performance. The graft copolymerization of glycidyl methacrylate (GMA) with cellulose fibers was initiated using Fe 2+ -thiourea dioxide(TDO)-H 2 O 2 in a mild aqueous medium; the synthesized polyglycidyl methacrylate grafted cellulose (CPGMA) was used to replace softwood bleached kraft pulp(SBKP) and hardwood bleached kraft pulp(HBKP), to study their retention and drainage aid behavior in the cationic polyacrylamide (CPAM)/colloidal SiO 2 / anionic polyacrylamide (APAM) system. Graft copolymerization significantly enhanced the fiber hydrophobicity. Additionally, the papermaking process drainage aid performance and retention rate of the filler increased significantly with an increase in the CPGMA substitution rate. A small amount of CPGMA (0.5 %) significantly improved the dewatering ability and some improved the retention performance of the wet end of papermaking. SBKP-polyglycidyl methacrylate grafted cellulose (S-CPGMA) exhibited better retention and drainage aid performance than HBKP-polyglycidyl methacrylate grafted cellulose (H-CPGMA). Thus, introducing Fe 2+ -thiourea dioxide(TDO)-H 2 O 2 initiated graft copolymerized S-CPGMA (in mild aqueous media) into pulp could improve the retention and drainage aid performance of the wet part of paper production.
Abstract：With the development of medical technology, venipuncture has become an indispensable means for human health assessment, diagnosis, and treatment.By far almost all of those actions are performed manually by medical personnel, which stimulates the demand for automation, also brings great social and economic prospect to automatic venipuncture robots.In order to relive the mental and physical burden of medical personnel as well as to promote the development of medical automation and wise information technology, venipuncture robots have become a worldwide research hotspot, and many researches have been released by research institutions.This research briefly summarizes the development status of venipuncture robots, analyzes the key technologies referred in venous sensing, autonomous decision making, robot structural design, control methods and so on.This paper further summarizes the existing problems and challenges, and finally looks forward to the development trends of venipuncture robots.
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