A differential-speed rolling(DSR) was applied to AZ31 magnesium alloy sample at different rolling temperatures of 473,523,573,and 623 K with 1-pass and 2-pass operations.The microstructural evolution and mechanical pr...A differential-speed rolling(DSR) was applied to AZ31 magnesium alloy sample at different rolling temperatures of 473,523,573,and 623 K with 1-pass and 2-pass operations.The microstructural evolution and mechanical properties of the deformed samples were investigated.The rolling temperature was found to be an important parameter affecting the microstructural development.After DSR at 473 K,the microstructure was more homogeneous than that obtained after deformation by equal-speed rolling(ESR).The fully recrystallized microstructures were generated after DSR at 573 and 623 K.As to mechanical properties,the yield strength(YS) and ultimate tensile strength(UTS) decreased monotonously with increasing rolling temperature.In contrast,the elongation of the DSR-deformed samples was improved as the rolling temperature increased.The strain hardening exponent(n) calculated by Hollomon equation increased with increasing the rolling temperature,which would explain an increase in the uniform elongation.展开更多
AIM: To investigate the rate of Helicobacter pylori (H. pylori) resistance to clarithromycin among ethnic minority patients in Guangxi, explore the underlying mechanisms, and analyze factors influencing genotype distr...AIM: To investigate the rate of Helicobacter pylori (H. pylori) resistance to clarithromycin among ethnic minority patients in Guangxi, explore the underlying mechanisms, and analyze factors influencing genotype distribution of H. pylori isolates.展开更多
P507 solvent extraction is the main method to separate and purify the rare earth products.The emulsification may be caused by the impurities in process of extracting rare earths,and these result in huge economic loss ...P507 solvent extraction is the main method to separate and purify the rare earth products.The emulsification may be caused by the impurities in process of extracting rare earths,and these result in huge economic loss and decrease the quality of rare earth products.In recent researches,the extractant was prone to emulsification,and aluminum content of rare earth products also increased,while aluminum concentration of feed was higher.Pointing to this problem,the structural change of saponification P507 extracting aluminum and lanthanum was investigated by infrared spectroscopy,and the results showed that Al ions exchanged with H of P-O-H to become P-O-Al.Because aluminum held the characteristic of hydrophilic after extracted in the form of hydroxyl polymer ions and this provided conditions for the formation of micro emulsion.The organic phase and aqueous phase were investigated by polarizing microscope after aluminum was extracted.The results showed that the organic phase was clear when the extraction capacity of Al was less than 5 g/L.If the extraction capacity of Al exceeded 5 g/L,it formed W/O of ME(micro emulsion),leading to form emulsion of the organic phase.When Al concentration of feed was less than 1 g/L,the aqueous phase would form O/W of ME.If aluminum was extracted by saponification P507 firstly,then the the organic phase loading aluminum extracted rare earth continually,the organic and aqueous phase formed emulsification easily.展开更多
In this paper .fatigue strength of T-type tubularjoints subjected to in-planebending or out-of-plane bending load is investigated By, considering material constantsand initial crack sizes as random variables and appl...In this paper .fatigue strength of T-type tubularjoints subjected to in-planebending or out-of-plane bending load is investigated By, considering material constantsand initial crack sizes as random variables and applying Monte Carlo simulation method, we have giyen a statistical analvsis on fatigue life. Simultaneously, linearregression analyses of computed resuldts are performed and compared with that of theknown experimental data.展开更多
The present research exploits diffusion brazing of mechanically alloyed Y 2O_3 dispersion strengthened nick-el-base MA760 and iron-base MA956 alloys using B-and P-containing thin foil and sputter coated interlayers.Mi...The present research exploits diffusion brazing of mechanically alloyed Y 2O_3 dispersion strengthened nick-el-base MA760 and iron-base MA956 alloys using B-and P-containing thin foil and sputter coated interlayers.Microstructures of diffission brazed interface before and after recrystallization annealing were investigated usingoptical metallography, electron microprobe analysis, and transmission electron microscopy. It has been foundthat B and P have a strons influence on the recrystallization behavior of these materials. Too high B or P levelsin the interlayers caused recrystallization of the base alloys during brazing process which was operated at temperatures below normal recrystallization points.展开更多
Using acridine dyes as sensitizers,the photoisomerization of three norbornadiene derivatives was investigated.The valence isomerization of nor- bornadiene derivatives(Ⅰ_a,Ⅰ_b,Ⅰ_c)gave their corresponding isomers of...Using acridine dyes as sensitizers,the photoisomerization of three norbornadiene derivatives was investigated.The valence isomerization of nor- bornadiene derivatives(Ⅰ_a,Ⅰ_b,Ⅰ_c)gave their corresponding isomers of quadri- cyclane(Ⅱ_a,Ⅱ_b,Ⅱ_c)operating with relatively high efficiency in an electron transfer mode.Their quantum yields of isomerization were determined and the reaction mechanism was discussed.展开更多
In recent years,with the continuous progress of science and technology,the development of information technology has also begun to change.The popularity of the application of modern information technology in the field...In recent years,with the continuous progress of science and technology,the development of information technology has also begun to change.The popularity of the application of modern information technology in the field of education is very high.College students can obtain the knowledge and content they need from the network.Teachers are no longer the only source of information for students,which promotes the improvement of students academic performance and cultivates students autonomous learning ability.As a university teacher,the author discusses how to motivate college students autonomous learning in the process of virtual project-based practical teaching,hoping that this paper can provide a certain direction for the future development of university education and guide college students to cultivate their autonomous learning ability.展开更多
Particulate composites based on isotactic polypropylene(iPP) and titanium dioxide(TiO 2) have been prepared and their morphology and thermal behavior investigated by scanning electron microscopy(SEM), differential sca...Particulate composites based on isotactic polypropylene(iPP) and titanium dioxide(TiO 2) have been prepared and their morphology and thermal behavior investigated by scanning electron microscopy(SEM), differential scanning calorimetry(DSC) and thermogravimetric analysis(TGA). Tensile tests were performed to assess the influence of TiO 2 on the mechanical properties of the iPP.展开更多
Sodium-ion batteries(SIBs)have attracted great interest for use as the next generation rechargeable batteries due to the abundant sodium natural resources and similar chemistry of lithium and sodium.TiO_(2)is an attra...Sodium-ion batteries(SIBs)have attracted great interest for use as the next generation rechargeable batteries due to the abundant sodium natural resources and similar chemistry of lithium and sodium.TiO_(2)is an attractive candidate as an anode for SIBs due to its high safety,low cost,appropriate voltage platform and good structural stability during repeated charge–discharge processes.However,the sodium storage mechanism of TiO_(2)for SIBs remains unclear,which appears to be different from the working mechanism in lithium-ion batteries.This article highlights a recent report by Passerini’s group,which successfully proposed a new sodium storage mechanism of TiO_(2)for SIBs.展开更多
The synergistic effect of nanoparticles(NPs)with alkyl polysulfides represents a promising avenue for enhancing extreme pressure(EP)performance in lubricants,potentially reducing the reliance on sulfur-containing addi...The synergistic effect of nanoparticles(NPs)with alkyl polysulfides represents a promising avenue for enhancing extreme pressure(EP)performance in lubricants,potentially reducing the reliance on sulfur-containing additives.However,the underlying synergistic mechanism remains unclear.In this study,oleic acidmodified titanium dioxide(TiO_(2)-OA)NPs and dialkyl pentasulfide(DPS)formed a mechanically interlocked EP tribo-film with a maximum thickness of approximately 1.4μm,demonstrating excellent load-bearing capabilities of up to 7,256 N(6.1 GPa).Under conditions of EP friction,the addition of TiO_(2)-OA NPs facilitates the development of a robust tribo-film of substantial thickness,which in turn bolsters the load-bearing capability of the lubricating oil.Surface analysis of EP wear scars using scanning electron microscopy(SEM),energy dispersive X-ray spectroscopy(EDS),and X-ray photoelectron spectroscopy(XPS)revealed that TiO_(2)-OA NPs were rapidly deposited and enriched at the friction interface with increasing load(3,530‒7,256 N)and friction time(0-10 s),which in turn compensated for the in situ wear generated by extreme shear.Cross-sectional analysis of EP wear scars revealed that the preferential formation of ferrous sulfide(FeS)and subsequent rapid enrichment and mechanical interlocking of TiO_(2)-OA NPs are essential for preventing welding and improving EP performance.This study presents novel insights into the synergistic mechanisms of NPs with sulfur-containing additives,advancing the widespread implementation and progress of NPs in the field of tribology.展开更多
基金supported by the research grant funded by the national research foundation(NRF-2014R1A1A2059004)
文摘A differential-speed rolling(DSR) was applied to AZ31 magnesium alloy sample at different rolling temperatures of 473,523,573,and 623 K with 1-pass and 2-pass operations.The microstructural evolution and mechanical properties of the deformed samples were investigated.The rolling temperature was found to be an important parameter affecting the microstructural development.After DSR at 473 K,the microstructure was more homogeneous than that obtained after deformation by equal-speed rolling(ESR).The fully recrystallized microstructures were generated after DSR at 573 and 623 K.As to mechanical properties,the yield strength(YS) and ultimate tensile strength(UTS) decreased monotonously with increasing rolling temperature.In contrast,the elongation of the DSR-deformed samples was improved as the rolling temperature increased.The strain hardening exponent(n) calculated by Hollomon equation increased with increasing the rolling temperature,which would explain an increase in the uniform elongation.
基金Supported by Nature Science Foundation of Guangxi,No.2012GXNSFAA053172The School to School and Enterprise to build the innovation platform in 2013,Guangxi Scientific Research,No.2013-8
文摘AIM: To investigate the rate of Helicobacter pylori (H. pylori) resistance to clarithromycin among ethnic minority patients in Guangxi, explore the underlying mechanisms, and analyze factors influencing genotype distribution of H. pylori isolates.
基金Project supported by the National Natural Science Foundation of China (50974042)Scientific Research Special Foundation of Doctor Subject of Chinese Universities (20090042120015)the Fundamental Research Funds for the Central Universities (N090302007)
文摘P507 solvent extraction is the main method to separate and purify the rare earth products.The emulsification may be caused by the impurities in process of extracting rare earths,and these result in huge economic loss and decrease the quality of rare earth products.In recent researches,the extractant was prone to emulsification,and aluminum content of rare earth products also increased,while aluminum concentration of feed was higher.Pointing to this problem,the structural change of saponification P507 extracting aluminum and lanthanum was investigated by infrared spectroscopy,and the results showed that Al ions exchanged with H of P-O-H to become P-O-Al.Because aluminum held the characteristic of hydrophilic after extracted in the form of hydroxyl polymer ions and this provided conditions for the formation of micro emulsion.The organic phase and aqueous phase were investigated by polarizing microscope after aluminum was extracted.The results showed that the organic phase was clear when the extraction capacity of Al was less than 5 g/L.If the extraction capacity of Al exceeded 5 g/L,it formed W/O of ME(micro emulsion),leading to form emulsion of the organic phase.When Al concentration of feed was less than 1 g/L,the aqueous phase would form O/W of ME.If aluminum was extracted by saponification P507 firstly,then the the organic phase loading aluminum extracted rare earth continually,the organic and aqueous phase formed emulsification easily.
文摘In this paper .fatigue strength of T-type tubularjoints subjected to in-planebending or out-of-plane bending load is investigated By, considering material constantsand initial crack sizes as random variables and applying Monte Carlo simulation method, we have giyen a statistical analvsis on fatigue life. Simultaneously, linearregression analyses of computed resuldts are performed and compared with that of theknown experimental data.
文摘The present research exploits diffusion brazing of mechanically alloyed Y 2O_3 dispersion strengthened nick-el-base MA760 and iron-base MA956 alloys using B-and P-containing thin foil and sputter coated interlayers.Microstructures of diffission brazed interface before and after recrystallization annealing were investigated usingoptical metallography, electron microprobe analysis, and transmission electron microscopy. It has been foundthat B and P have a strons influence on the recrystallization behavior of these materials. Too high B or P levelsin the interlayers caused recrystallization of the base alloys during brazing process which was operated at temperatures below normal recrystallization points.
基金the authors thank the help of professor Liang Xiao-guangZhang Bao-wen and Tung Chen-ho of our Institute
文摘Using acridine dyes as sensitizers,the photoisomerization of three norbornadiene derivatives was investigated.The valence isomerization of nor- bornadiene derivatives(Ⅰ_a,Ⅰ_b,Ⅰ_c)gave their corresponding isomers of quadri- cyclane(Ⅱ_a,Ⅱ_b,Ⅱ_c)operating with relatively high efficiency in an electron transfer mode.Their quantum yields of isomerization were determined and the reaction mechanism was discussed.
文摘In recent years,with the continuous progress of science and technology,the development of information technology has also begun to change.The popularity of the application of modern information technology in the field of education is very high.College students can obtain the knowledge and content they need from the network.Teachers are no longer the only source of information for students,which promotes the improvement of students academic performance and cultivates students autonomous learning ability.As a university teacher,the author discusses how to motivate college students autonomous learning in the process of virtual project-based practical teaching,hoping that this paper can provide a certain direction for the future development of university education and guide college students to cultivate their autonomous learning ability.
文摘Particulate composites based on isotactic polypropylene(iPP) and titanium dioxide(TiO 2) have been prepared and their morphology and thermal behavior investigated by scanning electron microscopy(SEM), differential scanning calorimetry(DSC) and thermogravimetric analysis(TGA). Tensile tests were performed to assess the influence of TiO 2 on the mechanical properties of the iPP.
文摘Sodium-ion batteries(SIBs)have attracted great interest for use as the next generation rechargeable batteries due to the abundant sodium natural resources and similar chemistry of lithium and sodium.TiO_(2)is an attractive candidate as an anode for SIBs due to its high safety,low cost,appropriate voltage platform and good structural stability during repeated charge–discharge processes.However,the sodium storage mechanism of TiO_(2)for SIBs remains unclear,which appears to be different from the working mechanism in lithium-ion batteries.This article highlights a recent report by Passerini’s group,which successfully proposed a new sodium storage mechanism of TiO_(2)for SIBs.
基金supported by the Shanghai Pujiang Program(No.22PJ1414700)the International Partnership Program of the Chinese Academy of Sciences(No.307GJHZ2022034GC)the Key Project of the Henan Province Science and Technology Research and Development Joint Funds(No.235101610007).
文摘The synergistic effect of nanoparticles(NPs)with alkyl polysulfides represents a promising avenue for enhancing extreme pressure(EP)performance in lubricants,potentially reducing the reliance on sulfur-containing additives.However,the underlying synergistic mechanism remains unclear.In this study,oleic acidmodified titanium dioxide(TiO_(2)-OA)NPs and dialkyl pentasulfide(DPS)formed a mechanically interlocked EP tribo-film with a maximum thickness of approximately 1.4μm,demonstrating excellent load-bearing capabilities of up to 7,256 N(6.1 GPa).Under conditions of EP friction,the addition of TiO_(2)-OA NPs facilitates the development of a robust tribo-film of substantial thickness,which in turn bolsters the load-bearing capability of the lubricating oil.Surface analysis of EP wear scars using scanning electron microscopy(SEM),energy dispersive X-ray spectroscopy(EDS),and X-ray photoelectron spectroscopy(XPS)revealed that TiO_(2)-OA NPs were rapidly deposited and enriched at the friction interface with increasing load(3,530‒7,256 N)and friction time(0-10 s),which in turn compensated for the in situ wear generated by extreme shear.Cross-sectional analysis of EP wear scars revealed that the preferential formation of ferrous sulfide(FeS)and subsequent rapid enrichment and mechanical interlocking of TiO_(2)-OA NPs are essential for preventing welding and improving EP performance.This study presents novel insights into the synergistic mechanisms of NPs with sulfur-containing additives,advancing the widespread implementation and progress of NPs in the field of tribology.
