In gas turbines, thermal barrier coatings （TBCs） applied by air plasma spraying are widely used to lower the temperature of hot components. To analyze the characteristics of TBCs such as residual stress, bond streng...In gas turbines, thermal barrier coatings （TBCs） applied by air plasma spraying are widely used to lower the temperature of hot components. To analyze the characteristics of TBCs such as residual stress, bond strength, fracture toughness, and crack propagation ratio, the Young＇s modulus and Poisson＇s ratio are important parameters. For TBC is a brittle and thin film, it is desirable to evaluate those properties while the coatings are bonded to a substrate. An atmospheric plasma spray MCrAIY bond coat and Yttria stabilized zirconia （YSZ） top coat are deposited onto a nickel-base superalloy GH150 substrate. The Young＇s modulus and Poisson＇s ratio are measured by cantilever beam bending with NDI. The method will be developed to test the Young＇ s modulus and Poisson ratio of other multilayer systems.展开更多
The elastic-plastic indentation properties of materials with varying ratio of hardness to Young’s modulus(H/E) were analyzed with the finite element method. And the indentation stress fields of materials with varying...The elastic-plastic indentation properties of materials with varying ratio of hardness to Young’s modulus(H/E) were analyzed with the finite element method. And the indentation stress fields of materials with varying ratio H/E on the surface were studied by the experiment. The results show that the penetration depth, contact radius, plastic pile-up and the degree of elastic recovery depend strongly on the ratio H/E. Moreover, graphs were established to describe the relationship between the elastic-plastic indentation parameters and H/E. The established graphs can be used to predict the H/E of materials when compared with experimental data.展开更多
BACKGROUND Digestive cancer has traditionally been thought of as a disease that mainly occurs in elderly individuals,and it has been ignored in young adults by both patients and physicians.AIM To describe the worldwid...BACKGROUND Digestive cancer has traditionally been thought of as a disease that mainly occurs in elderly individuals,and it has been ignored in young adults by both patients and physicians.AIM To describe the worldwide profile of digestive cancer incidence,mortality and corresponding trends among 20–39-year-olds,with major patterns highlighted by age,sex,development level,and geographical region.METHODS I performed a population-based study to quantify the burden of young adult digestive cancers worldwide.Global,regional,sex,and country-specific data estimates of the number of new cancer cases and cancer-associated deaths that occurred in 2020 were extracted from the GLOBOCAN Cancer Today database.To assess long-term trends in young adult digestive cancer,cancer incidence data and mortality data were obtained from the Cancer in Five Continents Plus database and the World Health Organization mortality database,respectively.The associations between the human development index(HDI)and digestive cancer burden in young adults were evaluated by linear regression analyses.RESULTS In 2020,there were an estimated 19292789 new cancer cases,resulting in 9958133 deaths worldwide,which equated to an age-standardized incidence rate(ASIR)of 5.16 and age-standardized mortality rate(ASMR)of 3.04,accounting for 12.24%of all new cancer cases and 25.26%of all cancer deaths occurring in young adults.The burden was disproportionally greater among males,with male:female ratios of 1.34 for incidence and 1.58 for mortality.The ASIRs were 2.1,1.4,and 1.0 per 100000 people per year,whereas the ASMRs were 0.83,1.1,and 0.62 per 100000 people per year for colorectal,liver,and gastric cancer,respectively.When assessed by geographical region and HDI levels,the cancer profile varied substantially,and a strong positive correlation between the mortality-to-incidence ratio of digestive cancer and HDI ranking was found(R^(2)=0.7388,P<0.001).CONCLUSION The most common digestive cancer types are colorectal,liver and gastric cancer.The global digestive cancer burden among young adults is greater among males and exhibits a positive association with socioeconomic status.The digestive cancer burden is heavy in young adults,reinforcing the need for primary and secondary prevention strategies.展开更多
A macromer, methoxypolyethylene glycol acrylate （MPEGAA）, was synthesized by direct esterification using methoxypolyethylene glycol （MPEG-1200） and acrylic acid （AA） as the main materials. MPEGAA was then used t...A macromer, methoxypolyethylene glycol acrylate （MPEGAA）, was synthesized by direct esterification using methoxypolyethylene glycol （MPEG-1200） and acrylic acid （AA） as the main materials. MPEGAA was then used to prepare a polyacrylic acid superplasticizer modified with 2-acrylamido-2- methylpropane sulfonic acid （AMPS）. A single-factor test was performed to investigate the effects of the molar ratio of acid to alcohol （n（AA）/n（MPEG））, inhibitor amount, catalyst amount, temperature, and time of esterification on the synthesis of MPEGAA. The experimental results showed that the optimal esterification conditions were as follows： n（AA）/n（MPEG）, 3.5：1; amount of hydroquinone （as an inhibitor）, 1.2%; amount of para-toluenesulfonic acid （as a catalyst）, 5.5%; reaction temperature, 95 ~C; and reaction time, 6 h. The AMPS- modified polyacrylic acid superplasticizer prepared under the optimal esterification conditions enabled the achievement and maintenance of high cement dispersibility. At an admixture amount of 0.15%, the cement paste fluidity was initially as high as 300 mm, and then decreased to 315 mm after 1 h and to 290 mm after 2 h.展开更多
Dynamic elastic parameters of coal are closely linked to crack characteristics and are lithology indicators in seismic exploration. This experimental study measured ultrasonic wave velocity of coal samples considering...Dynamic elastic parameters of coal are closely linked to crack characteristics and are lithology indicators in seismic exploration. This experimental study measured ultrasonic wave velocity of coal samples considering both parallel(90°) and perpendicular(0°) to bedding planes, and then calculated the dynamic elastic parameters(Edand ld) and their anisotropy values(AEdand Ald). The variations of Edand ld,as well as AEdand Aldwere analyzed under various confining stresses. The results show that: Firstly, a critical confining pressure exists, and significant variation in the parameters can be seen below this point and weak variation appears above it. Secondly, a positive correlation exists between Edand the square of P-wave velocity(VP2), and between AEdand the P-wave velocity anisotropy(AEP) as well; however, there is no clear correlation between ldand P-wave velocity(VP). Thirdly, according to the major controlling factors of anisotropy, the coal samples with different Edand ldas well as AEdand Aldcan be divided into two types: one is mainly controlled by bedding and cracks and the other one is mainly controlled by differences of mineral compositions in directions. Consequently, this study can provide theoretical basis for future research on the dynamic elastic parameters and anisotropy of coal.展开更多
文摘In gas turbines, thermal barrier coatings （TBCs） applied by air plasma spraying are widely used to lower the temperature of hot components. To analyze the characteristics of TBCs such as residual stress, bond strength, fracture toughness, and crack propagation ratio, the Young＇s modulus and Poisson＇s ratio are important parameters. For TBC is a brittle and thin film, it is desirable to evaluate those properties while the coatings are bonded to a substrate. An atmospheric plasma spray MCrAIY bond coat and Yttria stabilized zirconia （YSZ） top coat are deposited onto a nickel-base superalloy GH150 substrate. The Young＇s modulus and Poisson＇s ratio are measured by cantilever beam bending with NDI. The method will be developed to test the Young＇ s modulus and Poisson ratio of other multilayer systems.
基金Science Research Foundation of Shanghai Municipal Education Commission (No.06VZ004)
文摘The elastic-plastic indentation properties of materials with varying ratio of hardness to Young’s modulus(H/E) were analyzed with the finite element method. And the indentation stress fields of materials with varying ratio H/E on the surface were studied by the experiment. The results show that the penetration depth, contact radius, plastic pile-up and the degree of elastic recovery depend strongly on the ratio H/E. Moreover, graphs were established to describe the relationship between the elastic-plastic indentation parameters and H/E. The established graphs can be used to predict the H/E of materials when compared with experimental data.
基金the Scientific Research Projects of Health Commission of Mianyang City,No.202012.
文摘BACKGROUND Digestive cancer has traditionally been thought of as a disease that mainly occurs in elderly individuals,and it has been ignored in young adults by both patients and physicians.AIM To describe the worldwide profile of digestive cancer incidence,mortality and corresponding trends among 20–39-year-olds,with major patterns highlighted by age,sex,development level,and geographical region.METHODS I performed a population-based study to quantify the burden of young adult digestive cancers worldwide.Global,regional,sex,and country-specific data estimates of the number of new cancer cases and cancer-associated deaths that occurred in 2020 were extracted from the GLOBOCAN Cancer Today database.To assess long-term trends in young adult digestive cancer,cancer incidence data and mortality data were obtained from the Cancer in Five Continents Plus database and the World Health Organization mortality database,respectively.The associations between the human development index(HDI)and digestive cancer burden in young adults were evaluated by linear regression analyses.RESULTS In 2020,there were an estimated 19292789 new cancer cases,resulting in 9958133 deaths worldwide,which equated to an age-standardized incidence rate(ASIR)of 5.16 and age-standardized mortality rate(ASMR)of 3.04,accounting for 12.24%of all new cancer cases and 25.26%of all cancer deaths occurring in young adults.The burden was disproportionally greater among males,with male:female ratios of 1.34 for incidence and 1.58 for mortality.The ASIRs were 2.1,1.4,and 1.0 per 100000 people per year,whereas the ASMRs were 0.83,1.1,and 0.62 per 100000 people per year for colorectal,liver,and gastric cancer,respectively.When assessed by geographical region and HDI levels,the cancer profile varied substantially,and a strong positive correlation between the mortality-to-incidence ratio of digestive cancer and HDI ranking was found(R^(2)=0.7388,P<0.001).CONCLUSION The most common digestive cancer types are colorectal,liver and gastric cancer.The global digestive cancer burden among young adults is greater among males and exhibits a positive association with socioeconomic status.The digestive cancer burden is heavy in young adults,reinforcing the need for primary and secondary prevention strategies.
基金Funded by the Fujian Education Department(Nos.JA11329,JA12412)the Quanzhou(Fujian)Technology Research and Development Program(No.2010G7)
文摘A macromer, methoxypolyethylene glycol acrylate （MPEGAA）, was synthesized by direct esterification using methoxypolyethylene glycol （MPEG-1200） and acrylic acid （AA） as the main materials. MPEGAA was then used to prepare a polyacrylic acid superplasticizer modified with 2-acrylamido-2- methylpropane sulfonic acid （AMPS）. A single-factor test was performed to investigate the effects of the molar ratio of acid to alcohol （n（AA）/n（MPEG））, inhibitor amount, catalyst amount, temperature, and time of esterification on the synthesis of MPEGAA. The experimental results showed that the optimal esterification conditions were as follows： n（AA）/n（MPEG）, 3.5：1; amount of hydroquinone （as an inhibitor）, 1.2%; amount of para-toluenesulfonic acid （as a catalyst）, 5.5%; reaction temperature, 95 ~C; and reaction time, 6 h. The AMPS- modified polyacrylic acid superplasticizer prepared under the optimal esterification conditions enabled the achievement and maintenance of high cement dispersibility. At an admixture amount of 0.15%, the cement paste fluidity was initially as high as 300 mm, and then decreased to 315 mm after 1 h and to 290 mm after 2 h.
基金provided by the National Key Basic Research Development Program(No.2009CB219603)the Jiangsu Natural Science Fund Project(No.BK20130201)the Jiangsu Graduate Student Innovation Training Project(No.KYLX_1399)
文摘Dynamic elastic parameters of coal are closely linked to crack characteristics and are lithology indicators in seismic exploration. This experimental study measured ultrasonic wave velocity of coal samples considering both parallel(90°) and perpendicular(0°) to bedding planes, and then calculated the dynamic elastic parameters(Edand ld) and their anisotropy values(AEdand Ald). The variations of Edand ld,as well as AEdand Aldwere analyzed under various confining stresses. The results show that: Firstly, a critical confining pressure exists, and significant variation in the parameters can be seen below this point and weak variation appears above it. Secondly, a positive correlation exists between Edand the square of P-wave velocity(VP2), and between AEdand the P-wave velocity anisotropy(AEP) as well; however, there is no clear correlation between ldand P-wave velocity(VP). Thirdly, according to the major controlling factors of anisotropy, the coal samples with different Edand ldas well as AEdand Aldcan be divided into two types: one is mainly controlled by bedding and cracks and the other one is mainly controlled by differences of mineral compositions in directions. Consequently, this study can provide theoretical basis for future research on the dynamic elastic parameters and anisotropy of coal.
