Research on Issues and Countermeasures of Innovation Education among College Students

In today’s world, innovation is increasingly becoming a key factor in national economic and scientific and technological competition, and plays an important role in measuring a country’s comprehensive national power. Youth is the future of the country and the hope of the nation, and college students are one of the most energetic and creative groups of youth. With the continuous development and change of the society, it is more and more important to cultivate the innovative thinking and practical ability of college students for the development of the country and the progress of the society. Universities are the cradle for young people to grow up and become successful, and they are committed to cultivating innovative talents, shaping the innovative spirit of college students and improving their entrepreneurial ability. College students are the backbone of the future development of the country by cultivating students’ creativity, critical thinking and problem-solving ability, they can become the innovative leaders of the future society. However, in reality, there are still some problems that need to be solved in college students’ innovation spirit, such as the interaction of multiple factors such as the education system, neglect of colleges and universities, and the lack of attention of individuals, etc. We can improve the cultivation mode, establish a long-term mechanism, create an innovative atmosphere, and pay attention to self-cultivation in order to cultivate modernized talents with the spirit of innovation and entrepreneurial ability for the construction of an innovative country

Identification of Factors Limiting Heterologous Lipase Expression in the Cytoplasm and the Periplasm as well as Display on Cell Surface of Escherichia coli

Lipase B from Pseudozyma antarctica (PalB), had been expressed in several recombinant protein hosts and showed very good transesterification activity for biodiesel production. However, the functional expression could not be demonstrated until recently in the most popular recombinant protein expression system, e.g. Escherichia coli, and the expression performance stands improvement. The probable reason is that PalB is a lipase with more hydrophobic surface and three disulfide bonds and thus may not be easily expressed in E. coli functionally. This thesis focuses on the identification of factors limiting heterologous expression of PalB in E. coli through a systematic study by using several strategies, including the different expression compartments, fusion tags, folding factors, and host strains. Functional expression of PalB in the cytoplasm of E. coli was explored using BL21(DE3) and its mutant derivative Origami B(DE3) as the host. Bioactive PalB was obtained in the reduced cytoplasm of BL21(DE3), implying that the formation of disulfide bond was not strictly required for functional expression. However, the expression was ineffective and was primarily limited by formation of PalB inclusion bodies and growth arrest, both of which were associated with PalB misfolding and deteriorated physiology. The culture performance in terms of cell growth and PalB expression level could be significantly improved by simultaneous coexpression of multiple chaperones of trigger factor and GroEL/ES, but not individual coexpression of either one of them. It was proposed that the two chaperones mediate the early stage and late stage of cytoplasmic PalB folding and would be required simultaneously for boosting both the overall PalB synthesis rate and the cytoplasmic folding efficiency. On the other hand, a much higher bioactive PalB was produced in Origami B(DE3) harboring the same PalB expression vector. Furthermore, the significant high bioactive PalB was produced by coexpression of periplasmic folding factor without a signal peptide (e.g., coexpression of DsbA, and DsbC). Coexpression of DsbA was found to be effective in enhancing PalB expression and such an improvement was more pronounced in Origami B(DE3), suggesting that both folding and disulfide bond formation could be the major factors limiting PalB expression. The fusion tag technique was also explored by constructing several PalB fusions for the evaluation of their expression performance. While the solubility was enhanced for most PalB fusions, only the DsbA tag was effective in boosting PalB activity possibly via both enhanced solubility and correct disulfide bond formation. Our results suggest that solubilization of PalB fusions did not necessarily result in the development of PalB activity which could be closely associated with correct disulfide bond formation. While PalB was stably expressed in the cytoplasm, most of the expressed gene product aggregated in cells as inactive inclusion bodies. In contrast, PalB was extremely unstable when expressed in the periplasm, also leading to poor expression performance. Such unstable PalB can be rescued by coexpression of several periplasmic folding factors, such as DegP, FkpA, DsbA, and DsbC, but not cytoplasmic chaperones. As a result, the performance for functional PalB expression in the periplasm was significantly improved. This is the first report demonstrating the use of folding factors to rescue the extremely unstable gene product that is otherwise completely degradable. On the other hand, functional expression of PalB in the periplasm was explored using four fusion tags, e.g., DsbC, DsbA, maltose binding protein (MBP), and FLAG in the sequence of increasing expression efficacy. Amongst these fusion tags for functional expression of PalB, FLAG and MBP appear to be the most effective ones in terms of boosting enzyme activity and enhancing solubility of gene products, respectively. Overexpression of these PalB fusions often resulted in concomitant formation of insoluble inclusion bodies. Coexpression of a selection of periplasmic folding factors, including DegP (and its mutant variant of DegPS210A), FkpA, DsbA, DsbC, and a cocktail of SurA, FkpA, DsbA, and DsbC, could improve the expression performance. Coexpression of DsbA appeared to be the most effective in reducing the formation of inclusion bodies for the four PalB fusions, implying that functional expression of PalB could be limited by initial bridging of disulfide bonds. Culture performance for functional expression of PalB was optimized by overexpressing FLAG-PalB with DsbA coexpression, resulting in a high volumetric PalB activity of 360 U/liter. Without extracting protein from cells the whole cell can be directly used as a platform for the immobilized enzyme. Proof-of-concept experimentation was conducted by PalB display on the E. coli cell surface. By fusing the palB gene in between the signal peptide phoA and an autotransporter Protein EstA’s gene under the lac promoter, PalB was successfully displayed on the E. coli cell surface. However, cells encountered a severe physiological stress. Coexpression of various periplasmic folding factors, e.g., DegP, SurA, DsbA and DsbC could erease the physiological stress, but only DsbA was demonstrated to be effective to restore cell physiology and increase PalB expression level. Key words: enzyme, Escherichia coli, chaperone, folding factor, fusion tag, gene expression, Pseudozyma antarctica, lipase B, recombinant protein productio

Flexible versus simple trade-in strategy for remanufacturing

Some enterprises recently start to offer the flexible trade-in option to attract customers from competitors, in contrast to the simple one that only allows them to return used products to the same manufacturers for new. Based on analytical and numerical analyses, this study compares the environmental impacts of two trade-in strategies (simple versus flexible) in combination with different carbon tax policies. From the perspective of consumer switching behaviour, a Hotelling model with two market segments is established. Under the flexible trade-in strategy, the carbon emission of enterprises turns out to be significantly higher than that under the simple trade-in strategy. An appropriate carbon tax policy, especially with preferential tax rates on green products, is capable of guiding enterprises to choose a more environment-friendly trade-in strategy included in the model. The findings fill the research gap in comparing the pros and cons of simple and flexible trade-in strategies in terms of sustainable development, and provide managers and policy-makers the insights on how to promote the healthy development of the remanufacturing industry with trade-in strategizing and carbon taxation

Sharing economy of electric vehicle private charge posts

The increasing popularity of electric vehicles (EVs) leads to heightened demand for the charging infrastructure. More and more EV drivers install private charge posts, which can now be shared with others through certain mobile apps. This emerging phenomenon is becoming a prominent part of the sharing economy. To examine the impacts of post sharing on EV charging market, this study establishes game theory models on consumer choices among private, public, and shared options. Such peer-to-peer sharing and collaborative consumption redistribute the installation and operation costs of private charge posts in proportion to their increased utilization. Numerical analyses suggest that the sharing mode provides a win-win solution for charge post owners and non-owner consumers, as well as electricity distributors and public charging infrastructure operators. In the case of China, the estimated saving for charge post owners is between 20% and 50%, which can be translated into more non-government investment in the EV industry chain. The findings provide supporting evidence for policy-makers to promote private charge post sharing, especially with certain consumer subsidization at a reasonable level

Exempting battery electric vehicles from traffic restrictions: Impacts on market and environment under Pigovian taxation

In busy metropolitan areas, traffic restrictions based on the last digits of license plates effectively ease traffic jams and improve air quality. Recently, policy-makers in China exempted battery electric vehicles (BEV) from traffic restrictions to promote their diffusion in place of conventional vehicles (CV). To examine the impacts of such an exemption on consumers and manufacturers as well as the environment, this study models the duopoly competition between BEV and CV manufacturers as a Cournot game. The numerical analyses compare three traffic restriction policies concerning BEV and CV, and reveal the pros and cons of each. In particular, the BEV-exempted policy promotes customer adoption, industry development, and environment protection with the least consumer surplus loss. As supplementary measures, relevant vehicle purchase tax and carbon tax may make such a policy more effective, respectively, in short and long terms

CP3: Unifying Point Cloud Completion by Pretrain-Prompt-Predict Paradigm

Point cloud completion aims to predict complete shape from its partial observation. Current approaches mainly consist of generation and refinement stages in a coarse-to-fine style. However, the generation stage often lacks robustness to tackle different incomplete variations, while the refinement stage blindly recovers point clouds without the semantic awareness. To tackle these challenges, we unify point cloud Completion by a generic Pretrain-Prompt-Predict paradigm, namely CP3. Inspired by prompting approaches from NLP, we creatively reinterpret point cloud generation and refinement as the prompting and predicting stages, respectively. Then, we introduce a concise self-supervised pretraining stage before prompting. It can effectively increase robustness of point cloud generation, by an Incompletion-Of-Incompletion (IOI) pretext task. Moreover, we develop a novel Semantic Conditional Refinement (SCR) network at the predicting stage. It can discriminatively modulate multi-scale refinement with the guidance of semantics. Finally, extensive experiments demonstrate that our CP3 outperforms the state-of-the-art methods with a large margin