A high thrust-to-weight ratio poses challenges to the high-temperature performance of Ni-based superalloys. The oxidation behavior of GH4738 at extreme temperatures has been investigated by isothermal and non-isotherm...A high thrust-to-weight ratio poses challenges to the high-temperature performance of Ni-based superalloys. The oxidation behavior of GH4738 at extreme temperatures has been investigated by isothermal and non-isothermal experiments. As a result of the competitive diffusion of alloying elements, the oxide scale included an outermost porous oxide layer (OOL), an inner relatively dense oxide layer (IOL), and an internal oxide zone (IOZ), depending on the temperature and time. A high temperature led to the formation of large voids at the IOL/IOZ interface. At 1200℃, the continuity of the Cr-rich oxide layer in the IOL was destroyed, and thus, spallation occurred. Extension of oxidation time contributed to the size of Al-rich oxide particles with the increase in the IOZ. Based on this finding,the oxidation kinetics of GH4738 was discussed, and the corresponding oxidation behavior at 900-1100℃ was predicted.展开更多
[Objectives]This study was conducted to investigate the effects of Polygonatum odoratum polysaccharide(POP)on organ relative weights and reproductive hormone levels in male rats fed a high-fat diet.[Methods]Thirty hea...[Objectives]This study was conducted to investigate the effects of Polygonatum odoratum polysaccharide(POP)on organ relative weights and reproductive hormone levels in male rats fed a high-fat diet.[Methods]Thirty healthy male Sprague-Dawley(SD)rats were randomly divided into two groups according to their body weight:10 in normal control group(Group NC,n=10)and 20 in experimental group(n=20).The rats in experimental group were fed a high-fat diet for eight weeks before they were further randomly divided into two groups:high fat group(Group HF)and high fat+400 mg/(kg·d)POP group(Group HF+POP).In Group HF+POP,the rats were administered with POP for another six weeks,before their blood plasma was collected,and the relative weights of their testis and epididymis were calculated.The plasma levels of testosterone(T),estrogen(E2),follicle-stimulating hormone(FSH),cortisol(C)and luteinizing hormone(LH)were measured by radioimmunoassay,and the plasma levels of sex hormone-binding globulin(SHBG)and insulin-like growth factor-1(IGF-1)were determined by enzyme-linked immunosorbent assay.[Results]Compared with Group HF,POP could effectively inhibit rat obesity caused by high-fat diets,increase the relative weights of their testis and epididymis,plasma levels of LH,E2,FSH,T,SHBG and IGF-1,and reduce the plasma level of E2.[Conclusions]Polygonatum odoratum polysaccharide(POP)is able to effectively regulate the level of reproductive hormones in high-fat diet fed rats,and helps to protect their reproductive function.展开更多
基金financially supported by the National Key R&D Program of China (No.2021YFB3700400)the National Natural Science Foundation of China (Nos.52074030,51904021,and 52174294)。
文摘A high thrust-to-weight ratio poses challenges to the high-temperature performance of Ni-based superalloys. The oxidation behavior of GH4738 at extreme temperatures has been investigated by isothermal and non-isothermal experiments. As a result of the competitive diffusion of alloying elements, the oxide scale included an outermost porous oxide layer (OOL), an inner relatively dense oxide layer (IOL), and an internal oxide zone (IOZ), depending on the temperature and time. A high temperature led to the formation of large voids at the IOL/IOZ interface. At 1200℃, the continuity of the Cr-rich oxide layer in the IOL was destroyed, and thus, spallation occurred. Extension of oxidation time contributed to the size of Al-rich oxide particles with the increase in the IOZ. Based on this finding,the oxidation kinetics of GH4738 was discussed, and the corresponding oxidation behavior at 900-1100℃ was predicted.
基金Supported by Scientific Research Fund of the Hunan Provincial Education Department of China(19A259)Natural Science Foundation of Hunan Province(2022JJ30312)+2 种基金National Innovation Experiment Program for University Students(201910553013)2020 Innovation Experiment Program for College Students of Hunan University of HumanitiesScience and Technology(2020-17)。
文摘[Objectives]This study was conducted to investigate the effects of Polygonatum odoratum polysaccharide(POP)on organ relative weights and reproductive hormone levels in male rats fed a high-fat diet.[Methods]Thirty healthy male Sprague-Dawley(SD)rats were randomly divided into two groups according to their body weight:10 in normal control group(Group NC,n=10)and 20 in experimental group(n=20).The rats in experimental group were fed a high-fat diet for eight weeks before they were further randomly divided into two groups:high fat group(Group HF)and high fat+400 mg/(kg·d)POP group(Group HF+POP).In Group HF+POP,the rats were administered with POP for another six weeks,before their blood plasma was collected,and the relative weights of their testis and epididymis were calculated.The plasma levels of testosterone(T),estrogen(E2),follicle-stimulating hormone(FSH),cortisol(C)and luteinizing hormone(LH)were measured by radioimmunoassay,and the plasma levels of sex hormone-binding globulin(SHBG)and insulin-like growth factor-1(IGF-1)were determined by enzyme-linked immunosorbent assay.[Results]Compared with Group HF,POP could effectively inhibit rat obesity caused by high-fat diets,increase the relative weights of their testis and epididymis,plasma levels of LH,E2,FSH,T,SHBG and IGF-1,and reduce the plasma level of E2.[Conclusions]Polygonatum odoratum polysaccharide(POP)is able to effectively regulate the level of reproductive hormones in high-fat diet fed rats,and helps to protect their reproductive function.
