In this study, fatigue tests under different R ratios were conducted on the AZ61 Mg alloy to investigate its fatigue lifetimes and fatigue crack growth (FCG) behavior. The fracture surface of the failed specimens was ...In this study, fatigue tests under different R ratios were conducted on the AZ61 Mg alloy to investigate its fatigue lifetimes and fatigue crack growth (FCG) behavior. The fracture surface of the failed specimens was investigated using a scanning electron microscope to study the size of the intermetallic compounds from which the pioneer fatigue crack initiated and led to the final failure of the specimen. To determine the maximum size of the intermetallic compounds existing within the cross section of the specimen at higher risk, Gumbel’s extreme-value statistics were utilized. In the present study, the intermetallic compounds contained within the specimen were assumed to be the initial cracks existing in the material before the fatigue tests. A modified linear elastic fracture-mechanics parameter, M, proposed by McEvily et al., was used to analyze the short FCG behavior under different stress ratios, R. The relation between the rate of FCG and M parameter was found to be useful and appropriate for predicting the fatigue lifetimes under different R ratios. Moreover, the probabilistic stress-fatigue life (P-S-N) curve of the material under different R ratios could be predicted with this method, which utilizes both the FCG law and a statistical distribution of sizes of the most dangerous intermetallic compounds. The evaluated results were in good agreement with the experimental ones. This correspondence indicates that the estimation method proposed in the present study is effective for evaluation of the probabilistic stress-fatigue life (P-S-N) curve of the material under different R ratios.展开更多
In this study, fatigue crack growth (FCG) behavior of cemented carbide under the repeated thermal shock (RTS) was experimentally evaluated by using the thermal-shock experiment method developed by the authors. Tests w...In this study, fatigue crack growth (FCG) behavior of cemented carbide under the repeated thermal shock (RTS) was experimentally evaluated by using the thermal-shock experiment method developed by the authors. Tests were carried out using cemented carbide having two different WC crystal grain sizes. In addition, FCG behavior under rotating bending fatigue (RBF) test was investigated using the same cemented carbides. Then the FCG results obtained by the RTS test and the results of the RBF test obtained at stress ratio, R = -1, were compared with each other. Here, the stress ratio R is defined as, R = σmin/σmax;σmin and σmax are the minimum and the maximum stresses, respectively. From this comparison, it was found that the relation between the rate of fatigue crack growth (FCG) and the maximum stress intensity factor in the RTS tests was equivalent to the one obtained under the RBF tests at stress ratio of -1. From a practical point of view, this result is important as it indicates that it is not necessary to purposely perform RTS experiments. In this research, the effect of WC grain size on the short surface FCG behavior of the cemented carbide was also studied and discussed.展开更多
Background:Lenvatinib is used for unresectable hepatocellular carcinoma(u-HCC)as first-line,as well as second-and third-line therapy in Japan.We evaluated the therapeutic efficacy of newly developed ramucirumab when g...Background:Lenvatinib is used for unresectable hepatocellular carcinoma(u-HCC)as first-line,as well as second-and third-line therapy in Japan.We evaluated the therapeutic efficacy of newly developed ramucirumab when given after lenvatinib for post-progression treatment.Methods:Of 385 patients with u-HCC and treated with lenvatinib at 16 different institutions in Japan between May 2018 and January 2020,28 who received ramucirumab as the next treatment were enrolled and therapeutic responses were evaluated in a retrospective manner.Results:The median age of the 28 patients given ramucirumab was 70 years and the median albumin-bilirubin score was-2.19.Of the 28 patients,23 were male,21 were classified as Child-Pugh A and 7 as Child-Pugh B,and 25 were Barcelona Clinic Liver Cancer Stage C.Ramucirumab was given as second-line therapy in 14,third-line in 9,and fourth-line in 5.Therapeutic response was obtained in only 26 patients;the objective response rate was 3.8%(1/26)and the disease-control rate was 42.3%(11/26),with a median period to progression of 2.0 months.The reasons for discontinuation of ramucirumab were progression of disease in 16 and Grade 3 adverse events(gastrointestinal bleeding,ascites)in 2.Conclusions:The anticipated therapeutic efficacy of ramucirumab for post-progression treatment following lenvatinib was not seen in our early experience.展开更多
Increased gut permeability facilitates the uptake of food allergens into the bloodstream and triggers allergenic reactions.The present study aimed to evaluate the effect of Lactobacillus pentosus S-PT84(S-PT84)and Rub...Increased gut permeability facilitates the uptake of food allergens into the bloodstream and triggers allergenic reactions.The present study aimed to evaluate the effect of Lactobacillus pentosus S-PT84(S-PT84)and Rubus suavissimus leaf extract(RSLE)against egg ovomucoid(OVM)-uptake in lipopolysaccharide(LPS)-induced increased gut-permeability mice model of food allergy.Six-eight weeks old,female C57BL6 mice were continuously fed with LPS(300μg/kg BW),for 3 months to increase gut permeability.Reduction in the expression of sealing claudin-4,increase in the expression of pore-forming claudin-2,and increase in D-mannitol absorption into the blood plasma in the LPS treated groups suggested the increase in gut permeability after LPS treatment.The oral administration of major egg allergen,OVM,after LPS intervention,significantly increased the plasma mast cell protease-1 and OVMspecific IgE compared to the negative control group.These results indicated that continuous LPS intervention developed OVM-induced food allergy.However,both the treatment of S-PT84 and RSLE suppressed the claudin-2 expression and the gut permeability induced by LPS.Furthermore,S-PT84 and RSLE treatment also reduced the plasma mast cell protease-1 and OVM-specific IgE,indicating the potential beneficial effect against LPS intervention developed OVM-induced food allergy.These findings suggest that S-PT84 and RSLE ameliorated LPS induced gut permeability and food allergic reactions.展开更多
文摘In this study, fatigue tests under different R ratios were conducted on the AZ61 Mg alloy to investigate its fatigue lifetimes and fatigue crack growth (FCG) behavior. The fracture surface of the failed specimens was investigated using a scanning electron microscope to study the size of the intermetallic compounds from which the pioneer fatigue crack initiated and led to the final failure of the specimen. To determine the maximum size of the intermetallic compounds existing within the cross section of the specimen at higher risk, Gumbel’s extreme-value statistics were utilized. In the present study, the intermetallic compounds contained within the specimen were assumed to be the initial cracks existing in the material before the fatigue tests. A modified linear elastic fracture-mechanics parameter, M, proposed by McEvily et al., was used to analyze the short FCG behavior under different stress ratios, R. The relation between the rate of FCG and M parameter was found to be useful and appropriate for predicting the fatigue lifetimes under different R ratios. Moreover, the probabilistic stress-fatigue life (P-S-N) curve of the material under different R ratios could be predicted with this method, which utilizes both the FCG law and a statistical distribution of sizes of the most dangerous intermetallic compounds. The evaluated results were in good agreement with the experimental ones. This correspondence indicates that the estimation method proposed in the present study is effective for evaluation of the probabilistic stress-fatigue life (P-S-N) curve of the material under different R ratios.
文摘In this study, fatigue crack growth (FCG) behavior of cemented carbide under the repeated thermal shock (RTS) was experimentally evaluated by using the thermal-shock experiment method developed by the authors. Tests were carried out using cemented carbide having two different WC crystal grain sizes. In addition, FCG behavior under rotating bending fatigue (RBF) test was investigated using the same cemented carbides. Then the FCG results obtained by the RTS test and the results of the RBF test obtained at stress ratio, R = -1, were compared with each other. Here, the stress ratio R is defined as, R = σmin/σmax;σmin and σmax are the minimum and the maximum stresses, respectively. From this comparison, it was found that the relation between the rate of fatigue crack growth (FCG) and the maximum stress intensity factor in the RTS tests was equivalent to the one obtained under the RBF tests at stress ratio of -1. From a practical point of view, this result is important as it indicates that it is not necessary to purposely perform RTS experiments. In this research, the effect of WC grain size on the short surface FCG behavior of the cemented carbide was also studied and discussed.
文摘Background:Lenvatinib is used for unresectable hepatocellular carcinoma(u-HCC)as first-line,as well as second-and third-line therapy in Japan.We evaluated the therapeutic efficacy of newly developed ramucirumab when given after lenvatinib for post-progression treatment.Methods:Of 385 patients with u-HCC and treated with lenvatinib at 16 different institutions in Japan between May 2018 and January 2020,28 who received ramucirumab as the next treatment were enrolled and therapeutic responses were evaluated in a retrospective manner.Results:The median age of the 28 patients given ramucirumab was 70 years and the median albumin-bilirubin score was-2.19.Of the 28 patients,23 were male,21 were classified as Child-Pugh A and 7 as Child-Pugh B,and 25 were Barcelona Clinic Liver Cancer Stage C.Ramucirumab was given as second-line therapy in 14,third-line in 9,and fourth-line in 5.Therapeutic response was obtained in only 26 patients;the objective response rate was 3.8%(1/26)and the disease-control rate was 42.3%(11/26),with a median period to progression of 2.0 months.The reasons for discontinuation of ramucirumab were progression of disease in 16 and Grade 3 adverse events(gastrointestinal bleeding,ascites)in 2.Conclusions:The anticipated therapeutic efficacy of ramucirumab for post-progression treatment following lenvatinib was not seen in our early experience.
文摘Increased gut permeability facilitates the uptake of food allergens into the bloodstream and triggers allergenic reactions.The present study aimed to evaluate the effect of Lactobacillus pentosus S-PT84(S-PT84)and Rubus suavissimus leaf extract(RSLE)against egg ovomucoid(OVM)-uptake in lipopolysaccharide(LPS)-induced increased gut-permeability mice model of food allergy.Six-eight weeks old,female C57BL6 mice were continuously fed with LPS(300μg/kg BW),for 3 months to increase gut permeability.Reduction in the expression of sealing claudin-4,increase in the expression of pore-forming claudin-2,and increase in D-mannitol absorption into the blood plasma in the LPS treated groups suggested the increase in gut permeability after LPS treatment.The oral administration of major egg allergen,OVM,after LPS intervention,significantly increased the plasma mast cell protease-1 and OVMspecific IgE compared to the negative control group.These results indicated that continuous LPS intervention developed OVM-induced food allergy.However,both the treatment of S-PT84 and RSLE suppressed the claudin-2 expression and the gut permeability induced by LPS.Furthermore,S-PT84 and RSLE treatment also reduced the plasma mast cell protease-1 and OVM-specific IgE,indicating the potential beneficial effect against LPS intervention developed OVM-induced food allergy.These findings suggest that S-PT84 and RSLE ameliorated LPS induced gut permeability and food allergic reactions.
