The incidence of infertility has recently risen.Semen quality is an important male fertility indicator,and dietary factors can affect semen quality.We conducted this systematic review and meta-analysis to determine th...The incidence of infertility has recently risen.Semen quality is an important male fertility indicator,and dietary factors can affect semen quality.We conducted this systematic review and meta-analysis to determine the effects of healthy dietary patterns on semen quality.A literature search was conducted in 3 databases(Embase,Web of Science and PubMed)on August 21,2021.The included cross-sectional studies examined the influence of the Mediterranean,Dietary Approaches to Stop Hypertension(DASH),and prudent diet patterns on semen quality parameters;six studies(1244 subjects)were included.By comparing high consumption with low consumption of healthy dietary patterns,the results of the meta-analysis showed significantly higher sperm concentrations(mean difference[MD]=6.88×10^(6) ml^(−1),95%confidence interval[CI]:1.26×10^(6) ml^(−1)–12.49×10^(6) ml^(−1);P<0.05),a significant increase in total sperm count(MD=16.70×10^(6),95%CI:2.37×10^(6)–31.03×10^(6);P<0.05),and a significant increase in progressive sperm motility(MD=5.85%,95%CI:2.59%–9.12%;P<0.01).The sperm concentration,progressive sperm motility,and total sperm count were significantly higher in men with higher versus lower consumption of healthy dietary patterns.However,the results must be interpreted with caution.展开更多
A modified tempering treatment has been designed in order to avoid the direct transformation of retained austenite(Ar)during tempering of a low-alloy Cr-Mo-V steel.Instead of the direct transformation of Ar into ferri...A modified tempering treatment has been designed in order to avoid the direct transformation of retained austenite(Ar)during tempering of a low-alloy Cr-Mo-V steel.Instead of the direct transformation of Ar into ferrite and M23C6 carbides during conventional tempering at 700℃,transformation into aggregate of ferrite and cementite has been forced by a pre-tempering at 455℃ before conventional tempering.Experiments have been performed on specimens quenched with cooling rates 1.5,3 and 12℃/s,providing different types of Ar within the as-quenched microstructures.The results show that the tempering modification does not improve the Charpy impact toughness at the highest quenching rate of 12℃/s,where the specimens cannot incur cleavage cracking induced from fine and discontinuous M23C6 carbides along lath interfaces.For the lowest quenching rate 1.5℃/s,the Charpy impact toughness can be improved,and the failure is dominated by carbide aggregates,which originate from the decomposed products of blocky Ar.This is because the tempering modification effectively suppresses the formation of coarse M23C6 carbides at interfaces between the carbide aggregate and bainitic matrix,thereby resulting in a relatively homogeneous distribution of M23C6 carbides inside carbide aggregates.Therefore,the tempering modification is recommended for large-scale forgings,in which relatively high quenching rates are difficult to achieve.展开更多
基金supported by a grant from the National Nature Science Foundation of China(No.82173539 and No.81874268).
文摘The incidence of infertility has recently risen.Semen quality is an important male fertility indicator,and dietary factors can affect semen quality.We conducted this systematic review and meta-analysis to determine the effects of healthy dietary patterns on semen quality.A literature search was conducted in 3 databases(Embase,Web of Science and PubMed)on August 21,2021.The included cross-sectional studies examined the influence of the Mediterranean,Dietary Approaches to Stop Hypertension(DASH),and prudent diet patterns on semen quality parameters;six studies(1244 subjects)were included.By comparing high consumption with low consumption of healthy dietary patterns,the results of the meta-analysis showed significantly higher sperm concentrations(mean difference[MD]=6.88×10^(6) ml^(−1),95%confidence interval[CI]:1.26×10^(6) ml^(−1)–12.49×10^(6) ml^(−1);P<0.05),a significant increase in total sperm count(MD=16.70×10^(6),95%CI:2.37×10^(6)–31.03×10^(6);P<0.05),and a significant increase in progressive sperm motility(MD=5.85%,95%CI:2.59%–9.12%;P<0.01).The sperm concentration,progressive sperm motility,and total sperm count were significantly higher in men with higher versus lower consumption of healthy dietary patterns.However,the results must be interpreted with caution.
基金financially supported by the Shenyang National Laboratory for Materials Science,Institute of Metal Research,Chinese Academy of Sciences(Grant No.L2019F48)。
文摘A modified tempering treatment has been designed in order to avoid the direct transformation of retained austenite(Ar)during tempering of a low-alloy Cr-Mo-V steel.Instead of the direct transformation of Ar into ferrite and M23C6 carbides during conventional tempering at 700℃,transformation into aggregate of ferrite and cementite has been forced by a pre-tempering at 455℃ before conventional tempering.Experiments have been performed on specimens quenched with cooling rates 1.5,3 and 12℃/s,providing different types of Ar within the as-quenched microstructures.The results show that the tempering modification does not improve the Charpy impact toughness at the highest quenching rate of 12℃/s,where the specimens cannot incur cleavage cracking induced from fine and discontinuous M23C6 carbides along lath interfaces.For the lowest quenching rate 1.5℃/s,the Charpy impact toughness can be improved,and the failure is dominated by carbide aggregates,which originate from the decomposed products of blocky Ar.This is because the tempering modification effectively suppresses the formation of coarse M23C6 carbides at interfaces between the carbide aggregate and bainitic matrix,thereby resulting in a relatively homogeneous distribution of M23C6 carbides inside carbide aggregates.Therefore,the tempering modification is recommended for large-scale forgings,in which relatively high quenching rates are difficult to achieve.
