During the Ming and Qing Dynasties, epidemic diseases in Chaohu Lake basin lasted for 36 years. The formation of epidemic diseases was the result of the comprehensive effects of natural environment and climate characteristics, natural disasters, and social changes. In terms of natural environment, the general climate during the Ming and Qing Dynasties and the unique environmental characteristics in Chaohu Lake basin contributed to the epidemic diseases. In terms of natural disasters, the disaster system formed by the association of disaster elements formed the environment of epidemic diseases. Among them, the disaster elements of water, drought and locust were related to the formation of epidemic diseases most directly. In terms of social factors, epidemic diseases reflected the comprehensive effects of national epidemic prevention efforts, population changes, economic development, wars, and famines. The combination of multiple factors constituted the ecological field of epidemic diseases.

[Objective] One thermophilic bacterium was isolated from the hot spring in Tangchi, Lujiang, Anhui,and identified by molecular biological methods to study its morphological, physiological and growth characteristics,and the conditions of cellulase production were optimized. This study can provide reference for its biological science research and industrial application in the future. [Methods] Another thermophilic bacterium was isolated by high temperature culture, and its 16S rDNA gene sequence was determined. Its taxonomic status was determined by sequence alignment, phylogenetic tree construction and observation of cell and colony morphology. And its growth characteristics were studied. Through study of the effects of inoculum age, initial pH of fermentation medium, inoculum amount, fermentation temperature, rotation speed and fermentation time on cellulase production the cellulase production conditions were preliminarily optimized. [Results] Another thermophilic bacterium was isolated from the hot spring in Tangchi, Lujiang for the first time, which was named LJTC-2. The bacterium was Gram-positive and rod-shaped, belonging to Geobacillus. Its highest tolerance temperature was 73 °C and its optimum growth pH was about 7.0. The optimal fermentation conditions of LJTC-2 for cellulase production were determined as follows: inoculation age of 36 h, initial pH of fermentation medium of 6, inoculation amount of 2%, fermentation temperature of 60 °C, rotation speed of 180 r.min^-1, fermentation time of 60 h. Under these conditions, the enzyme activity was 183 mU.mL^-1, which was 17% higher than that before optimization. [Conclusion] The strain LJTC-2 was Geobacillus, and could tolerate high temperature of 73 °C. The results showed that LJTC-2 had the highest cellulase activity under the conditions of inoculation age of 36 h, initial pH of fermentation medium of 6, inoculation amount of 2%, 60°C , 180 .min^-1 and fermentation time of 60 h.

Based on China忆s provincial panel data from 2011 to 2019, the entropy method is used to synthesize comprehensive indicators of regional financial risks, to empirically test the impact of financial agglomeration on regional financial risks, and to analyze the mechanism of financial agglomeration on regional financial risks by using an intermediary effect model. The results show that: from a national perspective, financial gatherings intensify the formation of regional financial risks; from the perspective of regional regression, as the level of financial agglomeration increases, the effect of aggravating regional financial risks gradually decreases; as the level of financial agglomeration in the western, central and eastern regions increases, the effect of aggravating regional financial risks gradually decreases; among them, in the eastern region, high levels of agglomeration will have a restraining effect on regional financial risks; further research found that technological innovation has an intermediary effect of 22.35% in
the process of financial agglomeration忆s impact on regional financial risks.

With the rapid development and wide application of artificial intelligence technology, artificial intelligence has penetrated all areas of social life in our country. Meanwhile, artificial intelligence also poses new challenges to labor substitution and economic theory. The paper discusses the relationship between the use of artificial intelligence and employee turnover intention from a micro perspective, and on this basis, puts forward a moderated mediation model to investigate the mediating effect of job insecurity and the moderating effect of training investment. A survey of 398 front-line employees in industries that are closely related to artificial intelligence shows that the perception of artificial intelligence technology intensity has a significant positive impact on employees忆 turnover intention; job insecurity partially mediates the perception of artificial intelligence technology intensity and turnover intention; high investment in training will slow down the positive relationship between artificial intelligence technology intensity perception and job insecurity, and also adjust the indirect effect of artificial intelligence technology intensity perception on turnover intention through job insecurity.

In China with rapid economic development, the development of urban low-carbon transportation has become a hot issue to sectors of society. Based on the idea of evolutionary game, the evolutionary game model between the residents and the government in the low-carbon transportation system is built, and the strategic choice and dynamic evolution process between the two stakeholders are analyzed and simulated. The results show that the government plays a dominant role in the development of urban low-carbon transportation. The government should actively guide residents to low-carbon travel and improve the incentive mechanism for low-carbon travel residents. Residents should enhance their low-carbon awareness and voluntarily travel low-carbon to promote the development of urban lowcarbon transportation.

Strategic deviance is one of the common phenomena in development process of corporate strategy, and how it affects environmental investment has attracted much attention. Based on this, the article uses data of A-share listed companies in China from 2008 to 2017, and analyzes the impact of strategic deviance on environmental investment. The study finds that: Strategic deviance enhances environmental investment significantly. The nature of heavy pollution industry strengthens the positive relation between strategic deviance and environmental investment;state ownership strengthens the positive relation between strategic deviance and environmental investment. The article enriches literature on the influential factors of environmental investment from strategy perspective, and can help understand economic consequence of strategic deviance in China.

According to the SITC double-digit classification standard, 61 categories of export products are selected, and the export comparative advantage dynamics of Anhui and Jiangsu are analyzed based on the revealed symmetric comparative advantage index(RSCA). From 2000 to 2019, most of the export products of the two provinces have no comparative advantage, and the distribution of comparative advantage of Anhui is more scattered than that of Jiangsu. In the past 20 years, the export comparative advantage of the two provinces has changed significantly, which is the result of cumulative small changes in each year. About 30% of the most dynamic products in the two provinces remain in a state of survival. Therefore, the two provinces should steady export growth, adjust the structure, focus on the main export products, and implement the integration of the Yangtze River Delta market, so as to enhance the comparative advantage and survival ability of export.

For a positive integer m, a finite set of integers is said to be evenly distributed modulo m if the set contains an equal number of elements in each congruence class modulo m. This paper mainly studies the condition of m when the multiplicity of numerical semigroup is 4, and through the definition of numerical semigroup and related lemmas, it is proved that m satisfies when the gap set of numerical semigroups is evenly distributed.

Local recovery codes(LRC)are a class of linear codes. When the value of a component in the codeword is lost, it can be recovered by accessing a few (at most r) other components in the codeword. In this paper, we first construct LRC codes by using additive subgroups and multiplication subgroups as cosets on finite field F₂₇, and obtain that these LRC codes are optimal; Furthermore, we generalize to construct a cluster of optimal LRC codes for a general finite field F_3l with characteristic 3. Finally, the local resilience of these codes is compared with the latest LRC codes of the same kind. The results show that the constructed LRC codes have better local resilience.

Total factor productivity of scientific research is an important index to measure the innovation efficiency of scientific researchers in colleges and universities. The study takes 64 science and technology universities as the research object. Firstly, the data envelopment analysis method is used to determine the six-year mean value of scientific research total factor productivity of 64 science and technology universities, and then the fuzzy set qualitative comparative analysis method (fsQCA) is used to explore the promotion path of scientific research total factor productivity of science and technology universities. It is found that science and technology universities have four paths to improve the total factor productivity of scientific research, and environmental factor, technical factor, human factor, and capital factor can be the core elements of the paths to improve the total factor productivity of scientific research. The research results can provide reference and valuable suggestions for the improvement of scientific research total factor productivity in colleges and universities of science and technology.

[Objective] Succinic acid and lactic acid are the main products when Corynebacterium crenatum were cultured under anaerobic conditions. The knockout of lactate dehydrogenase gene(LdhA), a key enzyme for lactic acid production, can decrease the production of lactic acid and increase the flux of the metabolic pathway for succinic acid production. [Methods] In order to obtain the C. crenatum ?LdhA mutant strain, the upstream and downstream homologous recombination genes of LdhA and kanamycin resistance gene (Kn) were obtained by PCR. Afterwards, the targeting homologue recombination DNA and plasmid were constructed by fusion PCR. [Results] The targeting homologue recombination DNA of ?LdhA::Kn, targeting plasmid of pCVD442-?LdhA::Kn and donor bacteria of E.coli β2155/pCVD442-?LdhA::Kn were constructed, and the mutant strain of C. crenatum which had resistance to kanamycin was screened. [Conclusion] The results of PCR and lactate dehydrogenase activity analysis indicated that the LdhA in genome of C. crenatum was knockout and replaced by Kn. This study provides a foundation for producing succinic acid efficiently using C. crenatum.

The nonstoichiometric Bi_3.64Mo_0.36O_6.55 photocatalysts were synthesized by a chemical bathing method and a wet ultrasonic-assisted chemical synthesis method respectively. The phase, morphology and optical property of asprepared products were investigated by X-ray diffraction(XRD), field emission scanning microscopy(FESEM) and optical absorption spectrum. The results showed that BMO-1 products obtained by sonochemistry reaction are single cubic crystal quasi-cubric nanoparticles with about 30~50 nm in diameter. The photocatalytic performance was evaluated by the degradation organic dye MB under the xenon lamp irradiation. Findings suggested that BMO-1 samples display the superior photocatalytic activity, of which the apparent reaction rate constant is 1.8 and 15.5 times that of BMO-2 and commercial nano TiO₂ (P25) respectively.

[Objective] To predict and analyze the structure and function of Cronobacter malonaticus protein OmpA. [Methods] The amino acid sequence of protein OmpA of Cronobacter malonaticus was obtained from the NCBI database. The physicochemical and hydrophilic properties of the protein OmpA were analysed by using ProtParam tool and ProtScal tool. SignalP 5.0 tool TMHMM 2.0 tool and NetPhos 3.1 were used to analyze the signal peptides, transmembrane regions, and phosphorylation sites of protein OmpA. The secondary structure of protein OmpA was predicted by using modified SOPMA algorithm. The tertiary structure of protein OmpA was predicted by using SWISS-MODEL tool. Meanwhile, B cell epitopes and T cell epitopes of protein OmpA were predicted by using BepiPred tool and SYFPEITHI tool. Interaction proteins of protein OmpA were analyzed by using STRING tool. [Results] The protein OmpA of Cronobacter malonaticus LMG 23826 contains 347 amino acids. The protein has the following characteristics: Its property is a stable hydrophobic protein. The protein has signal peptides but no transmembrane regions, indicating that it was located outside the membrane of bacteria. [Conclusion] The OmpA protein is hydrophobic puter membrane protein with potential B and T cell epitopes. These findings provide a theoretical reference for study of the antigenicity of Cronobacter malonaticus and for development of highly efficient epitopebased vaccines.

Based on switched inductors and switched capacitors, a novel high-gain DC/DC converter with expandable structure is proposed. The article firstly analyzes the current research status of high-gain DC/DC converters; secondly, it analyzes the series topology based on switched inductors and switched capacitors; and then it analyzes the proposed novel high-gain converter based on switched inductors and switched capacitors. After the analysis, the working principle and main waveforms of the converter are studied; the voltage gain of the novel high-gain converter and the voltage stress of the switch tube and diode are studied; the state-space equation is modeled for the novel high-gain converter, the PI regulator is designed, and finally the Simulink closed-loop control system simulation of the proposed system is carried out. The simulation results show that the closed-loop system has excellent dynamic and steady-state performance, and achieves an output of 20 times the voltage gain. The novel DC/DC converter has the advantages of expandable structure and high gain.

This study uses convolutional neural network algorithm to implement a mask recognition system based on RISC-V architecture embedded platform. By comparing the current deep learning algorithms, we choose to use TensorFlow platform, YOLO algorithm and mask recognition model, and train them with appropriate amount of sparsity to reduce the model size so that they can run on the embedded platform. Then Dlib is adopted to train the feature point detection model to extract and save the feature values of the face, which can achieve the goal of recognizing faces. The LFW dataset is used as the experimental sample, and the experiment proves that the method can achieve high accuracy.

Aiming at the problem of low accuracy of road crack identification, a road crack identification method based on visual attention mechanism is proposed. Firstly, the source images are manually classified into non-crack, longitudinal crack, transverse crack, and grid crack. Then the corresponding texture information is obtained by Gabor filtering of the crack image, and the obtained texture image is segmented by K-means clustering algorithm. Then the attention-mechanism-based model SRM-Resnet (Style-based Recalibration Module Of Resnet) is used for classification and recognition. Finally, the proposed method is compared with several common attention-based models on four types of images. The results show that the road crack identification based on the improved visual attention mechanism proposed in this paper has greatly improved the accuracy of classification ability, and can effectively identify road cracks. The final identification accuracy can reach 0.966.

University students are the core stakeholder in the university. Their participation in university governance is not only an important part of establishing and improving a modern university system with Chinese characteristics, but also an important direction for the connotation construction of universities in the new era. Statistical and Chisquare test were used to carry out empirical analysis, and the results showed that students with different political status, educational level and cadre experience have different degrees of subjective cognition, channels of participation and evaluation criteria of participation in university governance, indicating that the effect of current Chinese students' participation in university governance is not ideal. Based on theoretical review and realistic analysis, the optimization design is carried out from the four aspects of reshaping the concept of "student-oriented", optimizing the power structure of university governance, unblocking the expression channels, and improving the student participation system. The design can protect the enthusiasm, initiative, and effectiveness of students' participation in university governance, and promote the modernization of higher education governance system and governance capabilities.

Based on the role-play theory, this study explores the dialectical unified relationship between the roles of teachers and students in the blended teaching model. The difference analysis is carried out from the three stages of role-play process—role determination, role performance and role construction; the unity is explained from the aspects of role standard, teaching content and teaching situation. The study shows that in blended teaching there are role positioning differences, which are based on "the relationship between teachers and students", the role performance differences that focus on "the teaching content", and the role construction differences that "take role interaction as the key". It is pointed out that the roles of teachers and students are normative ones; the interaction of the roles of teachers and students serves the teaching content; and the roles of teachers and students are unified in the teaching situation.

In order to cope with the challenges of the knowledge explosion era, Public Administration major urgently needs to strengthen practical, case-specific, and exploratory teaching to improve the level and quality of student training. The flipped classroom follows the concept of "student -oriented", takes education informatization as the driving force, and breaks through the ceiling of traditional classroom teaching effect through the online and offline blended teaching. So, it is conducive to the improvement of classroom teaching level and quality for Public Administration major. Based on discussing the effectiveness and connotation evolution of Public Administration flipped classroom, this paper puts forward a six -dimension model to discuss the internal requirements and essence of flipped classroom effectiveness from six dimensions—teachers, students, teaching content system, teaching methods, teaching environment and performance evaluation. Finally, the paper puts forward some suggestions on how to effectively carry out flipped classroom teaching in Public Administration major.

Based on the target of pre-service training of physical education (PE) teachers in primary and secondary schools in China under the strategy of strengthening China by sports, this paper explores the current situation of pre-service training of physical education teachers in primary and secondary schools in China, and finds that there exist actual dilemmas, such as insufficient target transformation from "physical education teacher" to "physical education and health teacher", curriculum as a discipline system rather than a capability system, weak cooperative education mechanism in practice teaching, and weak educational atmosphere in traditional sports culture. According to the needs of building a sports power, this paper puts forward the necessary paths of pre-service training of PE teachers in primary and secondary schools in the new era: changing the target and specifications of the pre-service training; optimizing the curriculum structure and content of pre-service training; improving the practical education ecosystem of pre-service training; and building the traditional sports culture education platform.

Consumption alienation, a phenomenon created by the material abundance under the commodity economy, embodies the inherent flaws of consumerism. College students with active and malleable minds dictate the construction of the future society, and the alienation of their attitudes and behaviors implies significant ramifications. Therefore, it is urgent to analyze the reasons for the phenomenon of alienated consumption by college students and put forward suggestions for their consumption ethics education. The study finds that college students' weak awareness of consumer ethics and the lack of educational guidance contribute to alienated consumption, such as vanitydriven consumption, overconsuming, and symbolic consumption. In the future, we can promote the cultivation of college students' correct consumer ethics from the aspects of optimizing the curriculum and reshaping the public opinion environment.