RESUMO
Rare earth (RE) addition to steels to produce RE steels has been widely applied when aiming to improve steel properties. However, RE steels have exhibited extremely variable mechanical performances, which has become a bottleneck in the past few decades for their production, utilization and related study. Here in this work, we discovered that the property variation of RE steels stems from the presence of oxygen-based inclusions. We proposed a dual low-oxygen technology, and keeping low levels of oxygen content in steel melts and particularly in the raw RE materials, which have long been ignored, to achieve impressively stable and favourable RE effects. The fatigue life is greatly improved by only parts-per-million-level RE addition, with a 40-fold improvement for the tension-compression fatigue life and a 40% enhancement of the rolling contact fatigue life. We find that RE appears to act by lowering the carbon diffusion rate and by retarding ferrite nucleation at the austenite grain boundaries. Our study reveals that only under very low-oxygen conditions can RE perform a vital role in purifying, modifying and micro-alloying steels, to improve the performance of RE steels.
Assuntos
Oxigênio , Aço , Ligas , CarbonoRESUMO
OBJECTIVE: To construct the interleukin-18-PE38 fusion gene expression vector and explore the expression of the fusion gene in the chondrocyte. METHODS: The recombinant eukaryotic expression vector PsecTag2B-IL-18-PE38 was constructed by inserting interleukin-18-PE38 fusion gene into eukaryotic expression vector PsecTag2B with molecular cloning technique. It was confirmed by restrictive enzymes (EcoR I) digestion assay and PCR. The vector was transfected into primary chrondrocyte by liposome protocol, and the transient expression was identified by fluorescence immunocytochemical assay. RESULTS: Restrictive enzymes digestion analysis and PCR revealed that the interleukin-18-PE38 fusion gene was cloned into the eukaryotic expression vector PsecTag2B successfully. Immunofluorescence photograph of fluorescence immunocytochemical method confirmed that the fusion gene can be expressed in the cytomembrane and cytoplasm. CONCLUSION: The results confirmed that PsecTag2B-IL-18-PE38 fusion gene can be expressed in the chondrocyte, which could serve as a foundation for the study on rheumatoid arthritis therapy.
Assuntos
ADP Ribose Transferases/genética , Toxinas Bacterianas/genética , Condrócitos/metabolismo , Exotoxinas/genética , Interleucina-18/genética , Proteínas Recombinantes de Fusão/biossíntese , Fatores de Virulência/genética , ADP Ribose Transferases/biossíntese , Animais , Animais Recém-Nascidos , Toxinas Bacterianas/biossíntese , Células Cultivadas , Condrócitos/citologia , Células Eucarióticas/metabolismo , Exotoxinas/biossíntese , Vetores Genéticos , Fatores Imunológicos/metabolismo , Interleucina-18/biossíntese , Lipossomos , Camundongos , Proteínas Recombinantes de Fusão/genética , Transfecção , Fatores de Virulência/biossíntese , Exotoxina A de Pseudomonas aeruginosaRESUMO
In order to develop a promising vaccine candidate utilizing a combined approach to induce both antibody production and T-cell activity, the DNA fragment containing MA of HCV with five conserved epitopes was synthesized. Two types of HCV vaccine candidates (the DNA type and DNA/polymers) were constructed using MA. PLA-PEG-PLA and PLGA-PEG-PLGA were synthesized and used as micelles with encapsulated plasmid pcDNA3.1(+)-MA. The preparation of copolymers, the cloning and analysis of recombinant plasmid DNA, in vitro expression, and immunogenicity in transgenic mice were evaluated in detail. The results indicated that even single immunization and oral immunization with DNA/polymers achieved satisfying immune responses in vivo tests. As biodegradable and nontoxic triblock copolymers, the novel copolymers demonstrated a great advantage, as they made long-term and single-immunizing vaccines possible; in addition, the copolymers showed a better adjuvant effect and scarcely any side effects.
Assuntos
Epitopos/genética , Hepacivirus/imunologia , Polietilenoglicóis/metabolismo , Vacinas de DNA/genética , Vacinas de DNA/imunologia , Animais , Células Hep G2 , Hepacivirus/genética , Hepatite C Crônica/prevenção & controle , Humanos , Imunidade Celular , Imunidade Humoral , Camundongos , Camundongos Endogâmicos BALB C , Camundongos Transgênicos , VacinaçãoRESUMO
AIM: To construct a novel eukaryotic expression plasmid including the recombinant immunotoxin DT390-mRantes and treat experimental autoimmune encephalomyelitis (EAE) in mice. METHODS: EAE in C57BL/6 mice were induced by the extracted MBP. The mRantes fragment was inserted into the eukaryotic expression plasmid SRalpha containing DT390. Then cationic liposome-embedded plasmid DNA was injected into the muscles of the hind-limbs in mice. The effect of DT390-mRantes was evaluated by observing clinical symptoms, pathological changes of brain, relative cytokine of peripheral blood, and the proportion of T cells and B cells. RESULTS: The recombinant immunotoxin DT390-mRantes was successfully constructed. Compared the mice in treated group with those in untreated group the clinical symptoms of EAE were alleviated, the infiltration of inflammatory cells were decreased, the IFN-gamma level was fallen, and the ratio of T/B cells was decreased. CONCLUSION: The recombinant immunotoxin DT390-mRantes has distinct effects on EAE in mice, which may be used for beneficial reference to the therapy of MS.