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Traditional access control models are hard to restrain the malicious behavior of authorized users. Accord-ingly, Hadoop platform with this access control model is difficult to prevent the risk of privacy disclosure. A model of access control based on risk was proposed. A risk function of information entropy was designed from users’ his-torical behavior based on setting the tags of subject and object. Furthermore, the tracking chain of risk was built, which could adjust the users’ access authority dynamically according to the risk value and its volatility. Combining with access token and risk supervision, the risk access control mechanism for big data privacy protection was real-ized, which could be applied to enhance the security of Hadoop Kerberos protocol. Finally, the experiment result shows that the model can constrain the authorized users’ access behavior effectively.

Both CO and H2 can be utilized as energy sources during the autotrophic growth of Clostridium ljungdahlii. In principle, CO is a more energetically and thermodynamically favorable energy source for gas fermentation in comparison to H2. Therefore, metabolism may vary during growth under different energy sources. In this study, C. ljungdahlii was fed with CO and/or CO2/H2 at pH 6.0 with a gas pressure of 0.1 MPa. C. ljungdahlii primarily produced acetate in the presence of H2 as an energy source, but produced alcohols with CO as an energy source under the same fermentation conditions. A key enzyme activity assay, metabolic flux analysis, and comparative transcriptomics were performed for investigating the response mechanism of C. ljungdahlii under different energy sources. A CO dehydrogenase and an aldehyde:ferredoxin oxidoreductase were found to play important roles in CO utilization and alcohol production. Based on these findings, novel metabolic schemes are proposed for C. ljungdahlii growing on CO and/or CO2/H2. These schemes indicate that more ATP is produced during CO-fermentation than during H2-fermentation, leading to increased alcohol production. [ABSTRACT FROM AUTHOR]

Both CO and H 2 can be utilized as energy sources during the autotrophic growth of Clostridium ljungdahlii . In principle, CO is a more energetically and thermodynamically favorable energy source for gas fermentation in comparison to H 2 . Therefore, metabolism may vary during growth under different energy sources. In this study, C. ljungdahlii was fed with CO and/or CO 2 /H 2 at pH 6.0 with a gas pressure of 0.1 MPa. C. ljungdahlii primarily produced acetate in the presence of H 2 as an energy source, but produced alcohols with CO as an energy source under the same fermentation conditions. A key enzyme activity assay, metabolic flux analysis, and comparative transcriptomics were performed for investigating the response mechanism of C. ljungdahlii under different energy sources. A CO dehydrogenase and an aldehyde:ferredoxin oxidoreductase were found to play important roles in CO utilization and alcohol production. Based on these findings, novel metabolic schemes are proposed for C. ljungdahlii growing on CO and/or CO 2 /H 2 . These schemes indicate that more ATP is produced during CO-fermentation than during H 2 -fermentation, leading to increased alcohol production., (Copyright © 2020 Zhu, Liu, Zhou, Yi, Lun, Wang, Tang and Li.)

Aim: To observe the therapeutic effect of corneal collagen cross-linking (CXL) in combination with liposomal amphotericin B in fungal corneal ulcers., Methods: New Zealand rabbits were induced fungal corneal ulcers by scratching and randomly divided into 3 groups, i.e. control, treated with CXL, and combined therapy of CXL with 0.25% liposomal amphotericin B ( n =5 each). The corneal lesions were documented with slit-lamp and confocal microscopy on 3, 7, 14, 21 and 28d after treatment. The corneas were examined with transmission electron microscopy (TEM) at 4wk., Results: A rabbit corneal ulcer model of Fusarium was successfully established. The corneal epithelium defect areas in the two treatment groups were smaller than that in the control group on 3, 7, 14 and 21d ( P <0.05). The corneal epithelium defect areas of the combined group was smaller than that of the CXL group ( P <0.05) on 7 and 14d, but there were no statistical differences on 3, 21 and 28d. The corneal epithelium defects of the two treatment groups have been healed by day 21. The corneal epithelium defects of the control group were healed on 28d. The diameters of the corneal collagen fiber bundles (42.960±7.383 nm in the CXL group and 37.040±4.160 nm in the combined group) were thicker than that of the control group (24.900±1.868 nm), but there was no difference between the two treatment groups. Some corneal collagen fiber bundles were distorted and with irregular arrangement, a large number of fibroblasts could be seen among them but no inflammatory cells in both treatment groups., Conclusion: CXL combined with liposomal amphotericin B have beneficial effects on fungal corneal ulcers. The combined therapy could alleviate corneal inflammattions, accelerate corneal repair, and shorten the course of disease.

Aim: To determine the effects of simulated intermittent high altitude hypoxia adaptation (IHA) on coronary capillary and coronary flow (CF) in rat hearts., Methods: Model of Langendorf-perfused isolated rat hearts were used to measure CF during ischemia-reperfusion, and immunoperoxidase staining assay and computer-aid morphometry analysis were conducted to determine the myocardial capillary densities. Cyclic GMP (cGMP) level in myocardium was measured by radio-immunoassay., Results: Pre-ischemia level of CF in IHA rats was higher (IHA28 13.4 mL/min+/-1.5 mL/min, IHA42 15.4 mL/min+/-2.0 mL/min, P < 0.01) than that of normoxic rats (11.0+/-0.8) mL/min, and the recovery of CF after ischemia-reperfusion was better in IHA rats. As an adaptive result, the myocardial capillary densities of the left ventricular myocardium in IHA rats were 1.5 times of those in normoxic control rats, but there was no apparent ventricular hypertrophy in IHA rats. Myocardial cGMP content (1.8+/-0.7) nmol/g in IHA rats were increased significantly compared with control rats (1.1+/-0.4) nmol/g, but cGMP level was not altered before and after ischemia-reperfusion in either group. It was also revealed that in isolated rat hearts perfused, myocardial function recovered better in IHA rats than that in normoxic control rats., Conclusion: IHA adaptation increased the tolerance of rat hearts against subsequent ischemia-reperfusion injury, and increase in coronary circulation and angiogenesis might be the mechanisms of myocardium protected by IHA.