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Objective Influence of metro tunnel closely under-passing the existing metro station and viaduct pile foundation is studied. Method Wulidun Station safety line tunnel on Hefei S1 Line closely under-passes the existing Wulidun Station on Metro Line 2. With this project as the background, the finite element software ABAQUS is used to build a three-dimensional model of the whole construction process, and the deformations of station structure and viaduct pile foundation under line by line excavation and simultaneous excavation of the above two lines are compared and analyzed. In order to investigate the applicability of similar engineering under different soil conditions, by changing the two parameters of soil cohesion and elastic modulus, the influence of the two parameters on the settlement of soil and station bottom plate during tunnel excavation are analyzed. Result & Conclusion After the completion of the tunnel excavation, the maximum settlements of the bottom plate of Metro Line 2 Wulidun Station under the two schemes are very similar being 0.73 mm and 0.77 mm, both meeting the requirements of the control standard. When the soil cohesion and elastic modulus are less than 70 kPa and 100 MPa respectively, the settlement of the station structure and the horizontal displacement of the pile foundation during tunnel excavation begin to increase significantly, which should be treated seriously.

Based on the demands of primary and secondary school campus planning and design for student health promotion in the "post-epidemic era", this paper uses meta-analysis to screen the quantitative results of 30 empirical studies at home and abroad in the past 20 years for statistical analysis, quantifies the impact of campus environment elements on the physical activity of primary and secondary school students, and compares the differences in research types, research objects' gender, age and measurement tools. It concludes that the effects should be explored in different dimensions and at different levels. Confounding factors such as policy environment and social environment should be considered to establish a multi-layer model to explore the influencing mechanism of the two factors, so as to provide a basis and reference for the construction and evaluation of healthy environment in schools. [ABSTRACT FROM AUTHOR]

Virtual Reality (VR) technology, as a new digital technology, has gradually been introduced into the art field and provided a new way of presenting traditional art exhibitions as the technology matures and becomes more popular. This paper introduces the main characteristics, different forms, impact, and future prospects of VR exhibitions around the theme of VR exhibitions, exploring how art intervenes in virtual space. The application of virtual reality technology in art exhibitions will become more and more extensive, which has an important driving role in promoting innovation and development of art exhibitions. [ABSTRACT FROM AUTHOR]

Objective To explore the therapeutic effect of "jian pi yi qi yang xue zhi tong" for treating bone metastasis of breast cancer and the clinical effect of improving pain symptoms. Methods A total of 80 patients with bone metastases from breast cancer were admitted. They were randomly divided into an observation group and a control group according to the random-number-table method. The control group was treated with zoledronic acid, whereas the observation group was treated with jian pi yi qi yang xue zhi tong prescriptions based on the control group. We compared the differences in the effects of different treatment plans on patients' pain symptoms, physical condition, and quality of life, as well as TNF-α, IL-6, and CRP levels. Results No significant difference was found in pain scores, physical condition scores, sleep quality scores, and quality of life scores, as well as CRP, IL-6, and TNF-α levels between the two groups of patients before treatment (all P > 0.05). At one, two, and four months after treatment, the pain scores of both groups of patients decreased, with the observation group having lower scores than the control group (P < 0.05). The total pain-relief rate of the observation group was higher than that of the control group (P < 0.05). After treatment, the sleep quality scores and the levels of CRP, IL-6, and TNF-α decreased, with the observation group having lower values than the control group (P < 0.05). The physical condition scores and the quality of life scores of both groups improved, with the observation group having higher values than the control group (P < 0.05). Conclusion In patients with bone metastases from breast cancer, oral treatment with jian pi yi qi yang xue zhi tong prescription has a significant effect. It substantially improves the pain symptoms, enhances the quality of sleep and life of patients, and reduces the levels of CRP, IL-6, and TNF-α.

Type II diabetes mellitus (T2DM) is one of the most prevalent metabolic diseases worldwide and α-glucosidase inhibitors are oral medications that are effective in the prevention and management of T2DM. Food-derived bioactive peptides are potential sources of α-glucosidase inhibitors, which have shown to have hypoglycemic activity and can effectively control postprandial blood glucose by inhibiting α-glucosidase activity, thus intervening and regulating T2DM, and have great prospects in the development of hypoglycemic peptide products. At present, there is no systematic strategy for exploring the structure-activity relationship, safety and bioavailability of food-derived α-glucosidase inhibitory peptides, hampering their research and development. In this paper, we systematically review the structural characteristics, toxicity, allergenicity, and bioavailability (gastrointestinal digestive enzyme resistance, mucus permeability, transit efficiency in small intestinal epithelial cells and liver metabolism) of food-derived α-glucosidase inhibitory peptides that have been successfully identified in recent years. This review is expected to provide a theoretical reference for the rational development of food-derived α-glucosidase inhibitory peptides and the further processing of related functional foods.

The eutrophication of water in reservoirs and lakes is getting worse year by year and has become a prominent issue of water environmental protection. In order to assess the degree of eutrophication and the changing trend of important drinking water sources in the coastal areas of western Guangdong and ensure the safety of drinking water, this paper takes Gaozhou Reservoir as the research object and based on the long-term monitoring results of eutrophication index of reservoirs from 2012 to 2019, using the comprehensive nutritional status index method and through the spatial and temporal analysis of the evaluation indexes and the comprehensive nutritional status of the reservoir. Based on W-F law the early warning model of reservoir eutrophication and classification and evaluation was established, to provide theoretical support and prevention and control methods for the ecological environment protection of reservoirs. The results show that Gaozhou Reservoir was in the middle nutritive state and the degree of eutrophication was more serious in the high water period than in the low water period. TLI(TN) is the biggest contributor of reservoir eutrophication and shows mild eutrophication in each single nutrient status index, and then Chl a, phosphorus and organic matter had little effect on the degree of eutrophication. The eutrophication status of the monitored sections of the reservoir fluctuates relatively steadily, the total TLI(∑) of Liangde Dam is lower than that of Shigu Reservoir area, and the comprehensive nutritional status of Shigu area is the tail > supply port > center. Based on the W-F law, an early warning model between the comprehensive impact index of eutrophication and the nutritional status index of Gaozhou Reservoir was constructed, to evaluate eutrophication status in different seasons from 2012 to 2019, and the results show that the comprehensive influence index value of dry period is less than that of flood period and consistent with the seasonal results, so the model has good warning effect. [ABSTRACT FROM AUTHOR]

Cancer is one of the leading causes of death from non-infectious diseases in the whole world. Moreover, effective screening and early diagnosis and treatment of cancers have always been a major clinical difficulty. Therefore, it is urgent that novel potential biomarkers or molecular targets are identified to improve the diagnosis and treatment of cancer patients. In recent years, it has been found that long non-coding RNAs (lncRNAs) are a series of main regulatory factors in biological behaviors and diseases including tumors, and are expected to become novel biomarkers and molecular targets for tumor detection and treatment. Actin filament-associated protein 1-antisense RNA 1 (AFAP1-AS1) was initially identified as a carcinogenic lncRNA in esophageal adenocarcinoma, and later as a carcinogenic regulator of various malignant tumors. The abnormal overexpression of AFAP1-AS1 can regulate the proliferation, apoptosis, invasion and metastasis of tumor cells through different molecular mechanisms. The up- regulation of AFAP1-AS1 in tumor tissues has important clinical significance. Understanding the function and mechanism of this lncRNA in cancers can further help to explore new strategies for the prevention and treatment of malignant tumors. Therefore, this paper reviewed the effects, relevant molecular mechanisms and potential clinical significance of AFAP1-AS1 in multiple human malignant tumors, so as to provide a scientific theoretical basis for its early clinical application.

The goal of relativistic heavy-ion collisions is to determine the phase boundary of quantum chromodynamics (QCD) phase transitions. Critically sensitive observables are suggested to be higher-order cumulants of conserved charges. The non-monotonous behavior of higher cumulants was observed at the relativistic heavy-ion collider (RHIC). However, it remains unclear whether these non-monotonous behaviors are critically related. We studied the influences of non-critical fluctuations, finite system size, and limited evolution time to determine if they cause non-monotonous behavior. First, we examined the minimum statistics required for measuring the fourth cumulant. The minimum statistic obtained using the centrality bin width correction (CBWC) method was 25 M. We suggest using a 0.1% centrality bin in the CBWC method instead of each Nch. With a 0.1 centrality bin width, 1 M statistics are sufficient. We then pointed out the statistical fluctuations from the limited number of final particles. By assuming the independent emission of each positive (or negative) charged particle, the statistical fluctuations of positive (or negative) charged particles were presented by a Poisson distribution, and the statistical fluctuations of net-charged particles were their evolution. The obtained statistical fluctuations for net protons, net electronic charges, and net baryons were consistent with those from the Hadron Resonance Gas model. In addition, the measured cumulants at RHIC/STAR are dominated by these Poisson-like statistical fluctuations. At the end of this section, we suggest the pooling method of mixed events and demonstrate that the sample of mixed events accurately presents the contributions of the background. Dynamic cumulants were defined as the cumulant of the original sample minus that of the mixed sample. Dynamical cumulants were shown to simultaneously reduce the influence of the statistical fluctuations, centrality bin width effects, and detector efficiency. Second, because the system is finite, the correlation length at the critical point is not developed to infinity in contrast to the system at thermal limits. Using a Monte Carlo simulation of the three-dimensional three-state Potts model, we demonstrated the fluctuations of the second- and fourth-order generalized susceptibilities near the temperatures of the external fields of the first-, second-, and crossover regions. Both the second- and fourth-order susceptibilities showed similar peak-like and oscillation-like fluctuations in the three regions. Therefore, non-monotonic fluctuations are associated with the second-order phase transition and the first-order phase and crossover in a finite-size system. The exponent of finite-size scaling (FSS) characterizes the order of transitions or crossover. To determine the parameters of the phase transition using the FSS, we studied the behavior of a fixed point in the FSS. To quantify the behavior of the fixed point, we define the width of the scaled observables of different sizes at a given temperature and scaling exponent ratio. The minimum width reveals the position of the fixed point in the plane of the temperature and scaling exponent ratio. The value of this ratio indicates the nature of the fixed point, which can be a critical, first-order phase transition line point, or crossover region point. To demonstrate the effectiveness of this method, we applied it to three typical samples produced by a three-dimensional three-state Potts model. The results show that the method is more precise and effective than conventional methods. Possible applications of the proposed method are also discussed. Finally, because of the limited evolution time, some processes in relativistic heavy-ion collisions may not reach thermal equilibrium. To estimate the influence of the nonequilibrium evolution, we used the three-dimensional Ising model with the Metropolis algorithm to study the evolution from nonequilibrium to equilibrium on the phase boundary. The order parameter exponentially approaches its equilibrium value, as suggested by the Langevin equation. The average relaxation time is defined. The relaxation time is well represented by the average relaxation time, which diverges as the zth power of the system size at a critical temperature, similar to the relaxation time in dynamical equations. During nonequilibrium evolution, the third and fourth cumulants of the order parameter could be positive or negative depending on the observation time, which is consistent with the calculations of dynamical models at the crossover side. The nonequilibrium evolution at the crossover side lasts briefly, and its influence is weaker than that at the first-order phase transition line. These qualitative features are instructive for experimentally determining the critical point and phase boundary in quantum chromodynamics.

BackgroundSilicon carbide junction barrier Schottky (SiC JBS) diode is a kind of power device based on wide bandgap semiconductor. SiC JBS diode is expected to become an important part of electric propulsion systems in the radiation application field in the future space exploration due to its excellent high-voltage, high-frequency and high-power characteristics. However, there are a large number of protons in the typical orbit of spacecraft, which always threaten the stable operation of spacecraft, including its key components.PurposeThis study aims to explore the resist ability of SiC JBSs to the degradation of medium energy proton irradiation, and clarify the mechanism of radiation effect of SiC JBSs from medium energy proton.MethodsBased the proton equivalent displacement damage dose in low Earth orbit for ten years, the SiC JBSs were firstly irradiated using 10 MeV protons at fluences ranging from 3×109 cm-2 to 3×1010 cm-2 at room temperature and without bias voltage. And the macro electrical characteristics of the SiC JBSs both before and after irradiation, including the forward current-voltage (I-V), reverse I-V and capacitance-voltage (C-V) characteristics, were tested. Then the irradiation-induced defects characteristics were tested by deep level transient spectrum (DLTS). Further, the related degradation mechanism that was associated with this phenomenon was also investigated using based on the test data and mathematical calculation. Finally, irradiation experiments of accelerator protons were carried out for commercial SiC JBSs.ResultsThe results show that the forward electrical characteristic of the SiC JBSs is stable, and the leakage current decreases at low reverse safety voltage. But the rated breakdown voltage is seriously degraded with the increase of irradiation fluence. The main contribution to the change of SiC JBSs characteristics originates from the increase of interface charge, deep level defects and Schottky barrier height, and the decrease of carrier density and carrier diffusion length in the drift region.ConclusionsAnalysis of the radiation damage process and mechanism of SiC JBSs in this study provides a research basis for its evaluation and verification before applied to medium energy proton environment.

Zheng Yanhong, in her new book Kenneth Rexroth and Chinese Culture, studies the influences of China on Rexroth from the perspectives of English translation of Chinese poems, poetry creation, Taoism and Zen Buddism, and probes into the causes of Rexroth's fascination with Chinese culture. Rexroth has himself well cultivated in the Chinese culture which is considered "the other" by many Western people, and grows into an excellent poet of English. Zheng's studies on Rexroth not only greatly deepen Chinese scholars' understanding of Rexroth but also serve as an ideal example of cultural dialogue and exchange. [ABSTRACT FROM AUTHOR]

With the rapid development of nuclear energy and space technology, application of high-voltage power devices based on SiC, especially the SiC MOSFET, is increasing. The problems of single event effect (SEE) caused by high-energy particle radiation in the radiation environment, such as, single event burnout (SEB) and single event gate rupture (SEGR), are becoming more and more prominent. In order to systematically understand the research progress of SiC MOSFET SEE, and accelerate the research of SiC MOSFET SEE mechanism and its radiation hardening technologies, the advantages of SiC MOSFET and the key problems in its radiation application are first demonstrated. Then, the simulation calculation, irradiation experiment and corresponding research results of SiC MOSFET SEE at home and abroad are comprehensively reviewed, and the main focus of related research is summarized. In addition, the possible reasons for the high sensitivity of SiC MOSFET to SEE is analyzed. Finally, possible future research directions of SiC MOSFET SEE are discussed according to current existing problems in this field. By systematically summarizing the research progress of SiC MOSFET SEE worldwide, it is expected to provide valuable reference for fully revealing the physical mechanism of SiC MOSFET SEE, and even further improving the radiation hardening technologies of SiC MOSFET to prevent the problem from SEE.

A new type of hybrid transmission device for plug-in hybrid electric vehicle（ PHEV） is present with planet gearbox. The parameters of the planet gearbox are obtained by using optimization method. In order to assess the economic efficiency and dynamic performance,the simulation model of the PHEV is set up based on the ADVISOR software,the vehicle parameters of a domestic SUV are used. The PHEV are simulated in NEDC cycle for charge depleting mode and charge sustaining mode,the results show that the presented new PHEV system can satisfy the requirement of new standard GB/T 32694—2016. The new system use only one motor and the hybrid device are compact,so that it expend low price and take small space in application.

Hardness gradient, residual stress gradient and the organization structure of surface super-hardened M50NiL steel roller and M50 steel roller were studied, the rolling contact fatigue life was measured, and the failure process was analyzed and compared by using surface profiler, Vickers hardness tester, X ray residual stress determinator, optical microscope, scanning electron microscope (SEM), rolling contact fatigue test machine and other equipment. The fatigue failure mechanism of surface super-hardened M50NiL steel was revealed. The results show that the fatigue failure mechanism of surface super-hardened M50Nil steel returns to the Hertz theory and shows typical contact fatigue characteristics. The high surface hardness, residual compressive stress and a good organization structure can completely inhibit the initiation of surface cracks; therefore, the failure mechanism is returned to the Hertz theory.

COVID-19 represents the most serious public health event in the past few decades of the 21 st century. The development of vaccines, neutralizing antibodies, and small molecule chemical agents have effectively prevented the rapid spread of COVID-19. However, the continued emergence of SARS-CoV-2 variants have weakened the efficiency of these vaccines and antibodies, which brought new challenges for searching novel anti-SARS-CoV-2 drugs and methods. In the process of SARS-CoV-2 infection, the virus firstly attaches to heparan sulphate on the cell surface of respiratory tract, then specifically binds to hACE2. The S protein of SARS-CoV-2 is a highly glycosylated protein, and glycosylation is also important for the binding of hACE2 to S protein. Furthermore, the S protein is recognized by a series of lectin receptors in host cells. These finding implies that glycosylation plays important roles in the invasion and infection of SARS-CoV-2. Based on the glycosylation pattern and glycan recognition mechanisms of SARS-CoV-2, it is possible to develop glycan inhibitors against COVID-19. Recent studies have shown that sulfated polysaccharides originated from marine sources, heparin and some other glycans display anti-SARS-CoV-2 activity. This review summarized the function of glycosylation of SARS-CoV-2, discoveries of glycan inhibitors and the underpinning molecular mechanisms, which will provide guidelines to develop glycan-based new drugs against SARS-CoV-2.

Poly(3-hydroxybutyrate-co-lactate) [P(3HB-co-LA)] belongs to the polyhydroxyalkanoates (PHA) family and possesses promising properties including biocompatibility and biodegradability. In this study, we directly synthesized P(3HB-co-LA) with glucose by introducing the β-ketothiolase and acetoacetyl-CoA reductase from Ralstonia eutropha, the engineered propionate CoA transferase from Clostridium propionicum and the engineered polyhydroxyalkanoate synthase from Pseudomonas fluorescens strain 2P24 into Escherichia coli. The polymer content was 83.9% (W/W), and the molar percentage of lactate reached 1.6%. On this basis, in order to accumulate lactate, we reduced the activity of respiratory chain by deleting the ubiX gene, which is involved in the synthesis of coenzyme Q8. Moreover, we removed the dld gene to avoid the conversion of lactate to pyruvate during the fermentation. With these manipulations, the molar percentage of lactate in the polymer was improved to 14.1%, with an 81.7% (W/W) of polymer content. The test results indicated that the strategy of reducing the activity of respiratory chain effectively increased the lactate units in the polymer, and it contributed a new approach to change the content of monomer components in the polymer.

Corn smut is a disease caused by Basidiomycetous fungus Ustilago maydis. This pathogen is a dimorphic fungus that needs to complete its sexual reproduction in living corn. We reviewed recent research reports of this disease, we divided the parasitization course of U. maydis into 7 stages in this paper, including the formation of pathogenic dikaryotic hyphae, attaching to the surface of host plant, penetrating the host epidermis, weakening host defense response, prolifering mycelium in host plant, inducing tumor in host tissue and the formation of chlamydospore. We also reviewed key genes involved in each stage and elaborate their function during pathogenesis. We present the sophisticated parasitic strategy of U. maydis in the process to achieve its sexual reproduction. The division of U. maydis parasitization course in this review will help understanding the interaction mechanisms between the pathogen and host plant, and provide new ideas for the prevention and control of such diseases.

Objective: To understand the exposed positions and levels of indium and its compounds in manufacture of liquid crystal displays, and to evaluate the degree of occupational hazard from indium and its compounds., Methods: On-site investigation of occupational health, occupational hazard monitoring, and occupational health examination were used to evaluate the degree of occupational hazard from indium and its compounds in three manufacturers of liquid crystal display panel in Shenzhen, Guangdong, China., Results: The time-weighted average (TWA) and short-term exposure limit (STEL) concentrations of indium and its compounds to which sputtering machine operating positions were exposed were less than 0.002~0.004 mg/m³ and 0.006~0.007 mg/m³, respectively, both of which complied with the National Hygienic Standard (PC-TWA = 0.1 mg/m³; PC-STEL = 0.3 mg/m³); the TWA and STEL concentrations of indium and its compounds to which grinding positions were exposed were 0.114~2.98 mg/m³ and 0.31~10.02 mg/m³, respectively, both of which exceeded the National Hygienic Standard with the highest concentration 33-fold higher than the standard. No significant health damages were found in exposed workers according to the results of occupational health examination., Conclusion: The grinding positions are the key to the control of occupational hazard from indium and its compounds in manufacture of liquid crystal display panel. The workers should be equipped with the anti-particulate full-face respirator, which is an effective way to prevent occupational hazard from indium and its compounds.

Objective: To investigate the cytotoxicity of indium chloride (InCl₃) and its effects on micro-nucleus formation in primary human lymphocytes cultured in vitro., Methods: The CCK-8 assay was used to evaluate the cytotoxicity of 24 h exposure to different concentrations of InCl₃(4, 40, 80, 200, 500, and 1 000 µmol/L) in lymphocytes cultured in vitro. The cytokinesis-block method was used to determine the micronucleus level in lymphocytes exposed to different concentrations of InCl₃and the effects of anti-oxidant vitamin C on micronucleus frequency., Results: Lymphocytes exposed to InCl₃of no less than 500 µmol/L had significantly lower survival rates than those in the control group (P < 0.05). Lymphocytes exposed to 80 µmol/L InCl₃had a significantly higher micronucleus frequency than those in the control group (P < 0.05). However, there was no further increase in micronucleus frequency of lymphocytes exposed to 200 µmol/L InCl₃. Lymphocytes cultured in whole blood and exposed to 500 or 1000 µmol/L InCl₃had a significantly increased micronucleus frequency than those in the control group (P < 0.001). The increase in micronucleus frequency of lymphocytes induced by indium could be partially antagonized by 20 or 100 µmol/L vitamin C., Conclusion: InCl₃can induce an increase in micronucleus frequency of primary human lymphocytes cultured in vitro, which might be associated with DNA damage induced by oxidative stress.

Objective: To study the effects of indium exposure on the relative content of mitochondrial ND1 gene in lymphocytes., Methods: Venous blood was obtained from 14 healthy workers and anticoagulated with heparin. Blood lymphocytes were separated and divided into three tube cultures. For two tubes in the exposed group, indium chloride was added to final concentrations of 0.2 mmol/L and 0.8 mmol/L, respectively. For one tube in the control group, an equal volume of normal saline solution was added. After incubation for 72 h, the relative content of mitochondrial gene in each group was determined using quantitative real-time PCR., Results: Lymphocytes exposed to 0.8 mmol/L indium chloride had a significantly higher relative content of mitochondrial gene than those exposed to 0.2 mmol/L indium chloride and those in the control group (P < 0.05, P < 0.05)., Conclusion: Lymphocytes exposed to a high concentration of indium and its compounds have an elevated relative content of mitochondrial ND1 gene, indicating increased oxidative DNA damage induced by exposure to a high concentration of indium and its compounds.

Objective: To investigate the sensitization effect of different chemical modifiers in the determination of indium in whole blood by graphite furnace atomic absorption spectrometry, and to develop a new method for the determination of indium in whole blood., Methods: A mixture of 0.3% HNO3 (V/V) + 0.1% Triton X-100 (V/V) was used as a diluent, and a solution of 1 000 µg/ml Pd (NO3)2 + 3 000 µg/ml Mg (NO3)2 was used as modifier. After being diluted five times, the concentration of indium of the blood was directly determined by graphite furnace atomic absorption spectrometry., Results: The detection limit of the method was 0.33 µg/L, the linear range was 0.33~100.00 µg/L, the relative standard deviation was 1.43%~2.65%, and the recovery rate was 98.3%~105.3%., Conclusion: The method is simple and fast and has high recovery and precision, and it is suitable for the determination of indium in whole blood.

For the current problems of the development of clinical pathways, a solution of clinical pathway information based on data mining is put forward in the paper. Using data mining techniques, the clinical pathway adapt to the conditions of the hospital is mined from the large amount of data available from the hospital, which reduces the development cycle and cost. The solutions of clinical path information based on data mining engine links seamlessly with existing hospital systems, which will provide a new way of thinking to the development of clinical pathways.

Objective: In order to further understand the difference in metabolic regulation between Escherichia coli DH5alpha and its acetate-tolerant mutant DA19, we analyzed the effect of supplementing adenine in defined media on metabolic fluxes in the two strains., Methods: E. coli DH5alpha and DA19 were continuously cultured in nitrogen-limited defined media without or with supplemented adenine. Based on mass balance and metabolic reaction stoichiometry, the metabolic fluxes in DH5alpha and DA19 at different culture condition were calculated, and the results were compared with the activities of key enzymes., Results: The supplementation of adenine decreased specific glucose consumption rate and specific acetate production rate, and improved growth yield coefficient on glucose of DH5alpha. Nevertheless, specific pyruvate production rate did not significantly change. Furthermore acetate split ratio decreased whereas pyruvate and TCA split ratios increased. Obvious changes were observed in the activities of phosphofructokinase, 6-phosphoglucose dehydrogenase and acetokinase. Compared with DH5alpha, the supplementation of adenine increased rate specific pyruvate production rate of DA19 nearly 57%, and other parameters did not change. In addition, it showed decreased TCA split ratio and greatly increased pyruvate split ratio, whereas no changes in the key enzyme activities were observed. The differences of enzyme activities in the two strains were reasonably consistent with those in metabolic fluxes., Conclusion: Because there were differences in the de novo biosynthesis capacity of purine nucleotides between DH5alpha and DA19, supplementation of adenine had completely different effect on metabolic fluxes in two strains.

To understand the effects of sugar whose uptake is dependent or independent on the phosphotransferase system (PTS), two-stage culture of Escherichia coli strain NZN111 that was constructed by disruption of IdhA and pflB encoding the fermentative lactate dehydrogenase (LDH) and pyruvate: formate lyase (PFL) of E. coli W1485, was carried out for organic acids production. When NZN111 was aerobically cultured on fructose (PTS dependent) or maltose (PTS independent), it fermented glucose with succinic acid and pyruvic acid as the major products in subsequent anaerobic culture. The experiments were also performed in a 5-L fermentor. The yields of succinic acid by the fructose-and maltose-grown NZN111 were 0.84 and 0.75 mol/mol, whereas the yields of pyruvic acid were 0.65 and 0.83 mol/mol, respectively. The final ratio of succinic acid to pyruvic acid in the anaerobic stage reached 1.73:1 and 1.21:1, respectively. The different behaviors in anaerobic fermentation by the fructose-, maltose- and glucose-grown NZN111 were likely caused by the regulation of catabolite repression in the aerobic culture stage.

Objective: To study the mechanism of the differences in cell growth and acetate production between Escherichia coli DH5alpha and its acetate-tolerant mutant DA19., Methods: Based on our previous analysis of the proteome and mass and energy balances for both strains, we first amplified the genes of atpIBEFHAGDC, purHD, and ndh, their regulation regions, as well as the regulation region of nuoA-N in both strains by PCR, and compared the sequences. Then, we constructed the recombinant strains DH5alpha (pTrc99a-atpA), DH5alpha (pTrc99a-purHD) and DH5alpha (pTrc99a-ndh) to study the effect of overexpression of atpA, purHD and ndh in DH5alpha on growth., Results: The sequences of the structural genes and the regulation regions in the two strains were completely identical with those of E. coli K-12. Overexpression of atpA, purHD and ndh separately in DH5alpha improved cell growth to some extent., Conclusion: Overexpression of ndh, purHD and atpA resulted in improved growth of DH5alpha, but the growth of these recombinant strains was still lower than that of DA19, indicating the importance of global regulation to the cellular metabolism.