Evaluation of inhibition effect on microbiologically influenced corrosion of Ti-5Cu alloy against marine Bacillus vietnamensis biofilm.

Titanium is highly susceptible to biofouling due to the poor toxicity and excellent biocompatibility. Microbiologically influenced corrosion of cp-Ti induced by Bacillus vietnamensis and the inhibition effect of Ti-5Cu alloy were evaluated using various electrochemical techniques and surface analyses. Electrochemical results revealed that, cp-Ti and Ti-5Cu alloy exhibited excellent passivation in the sterile medium. In biotic medium, however, attachment of B. vietnamensis biofilm to surface of cp-Ti accelerated the active dissolution and poisons repassivation. In contrast, cells adhered preferentially as a form of discrete colonies on Ti2Cu intermetallic phases. Release of Cu2+ ions induced damage in morphology of B. vietnamensis cells resulting in relative resistance to pitting corrosion estimated by 3.1 ± 0.6 µm and 2.0 ± 0.4 µm for cp-Ti and Ti-5Cu alloy, respectively.

Microstructure Evolution and Deformation Mechanisms of As-Cast Antibacterial Ti6Al4V-5Cu Alloy for Isothermal Forging Process.

The hot workability behavior of antibacterial Ti6Al4V-5Cu alloy was investigated using a hot compression experiment in the temperature range of 790-1040 °C and strain rate of 10-3-10 s-1 with a strain of 0.4. The deformation behavior of the alloy was characterized by Gleeble 3800 compression experiment, and the relationship among deformed microstructures and deformation parameters was established. The deformations of Ti6Al4V-5Cu alloy were temperature and strain rate-dependent. Higher temperature and lower strain rate made power dissipation efficiency (η) increase and reach 89%. The activation energies (Q) in the dual-phase (α + ß) and single ß phase regions were calculated as 175.43 and 159.03 kJ mol-1, respectively. In the dual (α + ß) phase region, with an increase in strain rate, flow-softening behavior was dominated, however in the single ß phase region such as processing at 940 °C. Flow stress increased slightly in which work-hardening behavior was dominated (especially between strain rates of 10-3-1 s-1). The deformation at various conditions exhibited different stress-strain profiles, providing an insight that work hardening and flow softening coexisted in Ti6Al4V-5Cu alloy. The relative intensity of oscillatory change in flow stress profile decreased as the strain rate decreased. The hot workability of Ti6Al4V-5Cu alloy was also accessed from the viewpoint of the sub-grain structure.

COVID-19 pandemic digitization lessons for sustainable development of micro-and small- enterprises.

The coronavirus (COVID-19) pandemic has undeniably influenced the global economy and environment. Major victims of the COVID-19 outbreak are Micro and Small Enterprises (MSEs), especially in developing countries, mainly because of limited use of digital technologies. This paper employs a literature review and personal insights to provide COVID-19 pandemic digitization lessons for sustainable development of MSEs from a technology for social good perspective. We develop a framework to support post COVID-19 digital transformation for sustainable development of MSEs. We find that digital payments, especially mobile money, should be a critical digital transformation priority for MSEs. Also, institutions must support MSE resources and capabilities to adopt digital transformation for business continuity, and sustainable production and consumption. Our study suggests that MSE managers and other stakeholders rethink their business strategies, incorporating crisis scenarios and business continuity plans to sustain customers virtually to enhance sustainable development. We also propose further research areas to improve the successful digital transformation of MSEs post COVID-19.

Assessing emission reduction effects from shifts of urban passenger transport modes by implementing targeted emission tax considering the whole fuel cycle.

Controlling the emission of urban passenger transport modes has become one of the most important tasks of governing urban air pollution. Most strategies only focused on carbon emission, whereas neglecting the influences of other pollutants (CO, HC, NOx, PM2.5), especially for upstream emissions from electricity generation caused by the electricity consumed during the operation of electrified transport modes. Based on the multinomial logit model (MNL), this study firstly calculated and evaluated the emission reduction effects brought about by the implementation of targeted emission taxes on different transport modes from the perspective of whole fuel cycle. Taking Jiangning District as an example, our research found that the policy implementing targeted emission tax for different transport modes can not only bring reduce 13.104 tons of CO, 0.327 tons of HC, 0.568 tons of NOx, and 0.140 tons of PM2.5, but also 26,726.82 (euro) of eco-environmental benefits for the treatment of air pollution. Our study can provide useful insights for shifting the structure of urban passenger transport modes, especially promoting the transfer of private cars to the urban green transport systems, to alleviate urban air pollution by formulating effective emission reduction strategies.

Cold Chain Logistics Management of Medicine with an Integrated Multi-Criteria Decision-Making Method.

Medicine is the main means to reduce cancer mortality. However, some medicines face various risks during transportation and storage due to the particularity of medicines, which must be kept at a low temperature to ensure their quality. In this regard, it is of great significance to evaluate and select drug cold chain logistics suppliers from different perspectives to ensure the quality of medicines and reduce the risks of transportation and storage. To solve such a multiple criteria decision-making (MCDM) problem, this paper proposes an integrated model based on the combination of the SWARA (stepwise weight assessment ratio analysis) and CoCoSo (combined compromise solution) methods under the probabilistic linguistic environment. An adjustment coefficient is introduced to the SWARA method to derive criteria weights, and an improved CoCoSo method is proposed to determine the ranking of alternatives. The two methods are extended to the probabilistic linguistic environment to enhance the applicability of the two methods. A case study on the selection of drug cold chain logistics suppliers is presented to demonstrate the applicability of the proposed integrated MCDM model. The advantages of the proposed methods are highlighted through comparative analyses.

[Comparative proteomics analysis of extracellular proteins from Listeria monocytogenes and its isogenic prfA deletion mutant].

OBJECTIVE: Positive regulatory factor A (PrfA) protein plays a key role in the pathogenicity of Listeria monocytogenes by regulating the expression of virulence genes. We studied the regulation functions of PrfA and its role in Listeria monocytogenes (Lm) virulence. METHOD: Extracellular proteins were obtained from the supernatants of parental strain LM4 and mutant strain LM4deltaprfA cultured in minimal medium. We used two-dimensional gel electrophoresis and matrix associated laser dissociation/ionization time of flight mass spectrometry (MALDI- TOF-MS) to analyze the differences of secreted proteins between LM4 and LM4deltaprfA. RESULTS: The electrophoresis results show that 31 different spots, 19 spots corresponding 12 proteins were identified by MALDI- TOF-MS. Some virulence related proteins were verified, such as InlC, ActA and LLO. Some new proteins that are regulated by PrfA include D-alanyl-D-alanine carboxypeptidase, dipeptide Glycine and Trytophan (GW) repeat-containing surface protein, transcriptional regulator and some hypothetical proteins with unknown functions. Real-time quantitative PCR was conducted to verify the proteomics results. The mRNA expression level of hly, actA and inlC gene was significantly reduced, and that of D-alanyl-D-alanine carboxypeptidase and GW repeat-containing surface protein's synthesis also had a reduction in LM4deltaprfA strain. CONCLUSION: PrfA plays key roles on the regulation of genes in LIPI- I and LIPI- II.

[Prokaryotic expression and identification of HPV16 E7 protein].

HPV16 E7 fusion protein was expressed in E. coli BL21, and its applied value for HPV was evaluated. HPV16 E7 gene was amplified by PCR, and cloned into prokaryotic expression vector pGEX6p-1. The recombinant plasmid was transformed into E. coli BL21, and HPV16 E7 fusion was expressed through IPTG induction. The expressed product was analyzed by SDS-PAGE and Western blot, subsequently purified according to Glutathione Sepharose 4B purification procedure. An indirect ELISA with the purified fusion protein as the coating antigen was then established to detect E7 serum antibodies from mice immunized with recombinant Listeria monocytogenes delivering HPV16 E7. The results demonstrated that the soluble fusion protein was highly expressed at 25 degrees C after induction with 0.5 mM IPTG. Furthermore, the result of Western blot analysis showed that the fusion protein had good specific reaction with an anti-E7 monoclonal antibody. Indirect ELISA result confirmed that the fusion protein could detect the serum antibodies against E7 with a titer of 1:200. The expressed GST-E7 fusion protein was immunocompetent, which was useful in the research of E7 biological function and therapeutic vaccine.

[Construction and characterization of Listeria monocytogenes deltaprfA mutant strains].

OBJECTIVE: Listeria monocytogenes (Lm) is an important pathogen that can cause serious listeriosis in humans and animals. The pathogenicity of Lm has a close relationship with the PrfA protein regulating the expression of virulence genes. Therefore, we studied the regulation functions of PrfA and its role on Lm's virulence. METHODS: The prfA genes of LM4, serotype 1/2a, and F4636, serotype 4b, were deleted by homologous recombination technology, and the biological characteristics of the mutants were further studied. RESULTS: The prfA gene deleted strains LM4deltaprfA and F4636deltaprfA and their back mutation strains were successfully constructed. The results show that the hemolysis activity was lost in prfA deleted strains and was recovered in the reverse mutant strains. The prfA deleted strains lost phospholipase activity; their adhesion and invasion ability significantly decreased. Furthermore, their 50% lethal doses (LD50) were 5 logs higher comparing with wild type strains. CONCLUSION: PrfA regulates hly, plcB and inl gene family and affects significantly Lm's virulence.