Four new rod-coil diblock molecules, which had well-defined para-phenylene oligomers (PPP, from biphenyl to quinquephenyl) as rigid segments and poly(ethylene oxide) (PEO, M-w ca. 750) as flexible segments, were synth...Four new rod-coil diblock molecules, which had well-defined para-phenylene oligomers (PPP, from biphenyl to quinquephenyl) as rigid segments and poly(ethylene oxide) (PEO, M-w ca. 750) as flexible segments, were synthesized. The chemical structure and the number of repeating unit in PEO coil and PPP rod were characterized by H-1-NMR and MALDI-TOF mass spectrometry. The diblock oligomers showed good solubility in common organic solvents and aggregated in water as characterized by a blue shift in UV-vis absorption spectra, a red shift in emission spectra, quenching of the fluorescence and formation of the microfibrilla and fractal-like structures. The formation of different supramolecular structures meant that this effort might lead to commercial important highly organized functional materials.展开更多
Geographically connected to the Central Plain and Yangtze River delta,Shandong,located in coastal north China,is home to successive ancient cultures and acts as a melting pot for exchanging material culture,agricultur...Geographically connected to the Central Plain and Yangtze River delta,Shandong,located in coastal north China,is home to successive ancient cultures and acts as a melting pot for exchanging material culture,agriculture,and technologies among distinct societies.Neolithic cultures in Shandong include Houli(~8.3–7.4 thousand years ago(kya)),Beixin(~7.4–6.2 kya),Dawenkou(~6.2–4.6 kya)and Longshan culture(~4.6–4 kya).The Dawenkou culture originated from the local Beixin culture that developed during the early period of the Neolithic Age and corresponds to the middle and late period of the Yangshao culture of the Central Plains.In the middle and late Dawenkou culture period(~6–4.6 kya),the reliance of Shandong was shifting from hunting and gathering to farming,including dryland millet and wetland rice agriculture,as well as independently domesticated wild soybeans[1–3].This process is often described in archaeology as the‘‘Neolithic revolution o or‘‘Neolithizationo.Some of the painted patterns on the pottery of Dawenkou seem to resemble those of the Yangshao culture,indicating a culture diffusion between the Dawenkou and Yangshao cultures[4].It has been long debated whether the migration of farming groups from Yangshao culture introduced the Neolithic revolution to the Dawenkou people.展开更多
The surface-initiated Rolling Contact Fatigue(RCF)including pitting and micro-pitting is one of the key issues affecting the reliability of tribological components such as gears and bearings used in various devices.In...The surface-initiated Rolling Contact Fatigue(RCF)including pitting and micro-pitting is one of the key issues affecting the reliability of tribological components such as gears and bearings used in various devices.In this work,a surface-initiated crack Finite Element(FE)model which considers the effect of lubricant on crack faces was developed to investigate surface-initiated RCF using an automatic crack propagating Python script.Different lubricating states,initial crack parameters and loading conditions were simulated to analyze the evolution of crack propagation and the Stress Intensity Factors(SIFs).The RCF crack propagation path and life were predicted by employing the Maximum Tangential Stress(MTS)criterion coupled with the Paris’s law.A typical RCF failure is predicted in the numerical simulation.Results reveal that the lubricating pressurization dominates the surface-initiated RCF.In addition,the initial crack angle has a significant effect on the RCF crack propagation path and the fatigue life.展开更多
基金This work has been supported by the National Natural Science Foundation of China (Grants 29874003 and 29992590-4), the Research Fund for Doctoral Program of Higher Education (Grant 99000136) and the Teaching and Research Award Fund for Outstanding Young
文摘Four new rod-coil diblock molecules, which had well-defined para-phenylene oligomers (PPP, from biphenyl to quinquephenyl) as rigid segments and poly(ethylene oxide) (PEO, M-w ca. 750) as flexible segments, were synthesized. The chemical structure and the number of repeating unit in PEO coil and PPP rod were characterized by H-1-NMR and MALDI-TOF mass spectrometry. The diblock oligomers showed good solubility in common organic solvents and aggregated in water as characterized by a blue shift in UV-vis absorption spectra, a red shift in emission spectra, quenching of the fluorescence and formation of the microfibrilla and fractal-like structures. The formation of different supramolecular structures meant that this effort might lead to commercial important highly organized functional materials.
基金supported by the National Science Fund for Distinguished Young Scholars from National Natural Science Foundation of China(T2425014)the National Natural Science Foundation of China(32270667)+5 种基金the National Social Science Foundation of China(21BKG037)the Natural Science Foundation of Fujian Province of China(2023J06013)the National Key Research and Development Program(2023YFC3303701-02)the Major Project of the National Social Science Foundation of China(21&ZD285)Open Research Fund of State Key Laboratory of Genetic Engineering at Fudan University(SKLGE-2310)Open Research Fund of Forensic Genetics Key Laboratory of the Ministry of Public Security(2023FGKFKT07)。
文摘Geographically connected to the Central Plain and Yangtze River delta,Shandong,located in coastal north China,is home to successive ancient cultures and acts as a melting pot for exchanging material culture,agriculture,and technologies among distinct societies.Neolithic cultures in Shandong include Houli(~8.3–7.4 thousand years ago(kya)),Beixin(~7.4–6.2 kya),Dawenkou(~6.2–4.6 kya)and Longshan culture(~4.6–4 kya).The Dawenkou culture originated from the local Beixin culture that developed during the early period of the Neolithic Age and corresponds to the middle and late period of the Yangshao culture of the Central Plains.In the middle and late Dawenkou culture period(~6–4.6 kya),the reliance of Shandong was shifting from hunting and gathering to farming,including dryland millet and wetland rice agriculture,as well as independently domesticated wild soybeans[1–3].This process is often described in archaeology as the‘‘Neolithic revolution o or‘‘Neolithizationo.Some of the painted patterns on the pottery of Dawenkou seem to resemble those of the Yangshao culture,indicating a culture diffusion between the Dawenkou and Yangshao cultures[4].It has been long debated whether the migration of farming groups from Yangshao culture introduced the Neolithic revolution to the Dawenkou people.
基金supported by the National Key R&D Program of China(No.2018YFB2001300)。
文摘The surface-initiated Rolling Contact Fatigue(RCF)including pitting and micro-pitting is one of the key issues affecting the reliability of tribological components such as gears and bearings used in various devices.In this work,a surface-initiated crack Finite Element(FE)model which considers the effect of lubricant on crack faces was developed to investigate surface-initiated RCF using an automatic crack propagating Python script.Different lubricating states,initial crack parameters and loading conditions were simulated to analyze the evolution of crack propagation and the Stress Intensity Factors(SIFs).The RCF crack propagation path and life were predicted by employing the Maximum Tangential Stress(MTS)criterion coupled with the Paris’s law.A typical RCF failure is predicted in the numerical simulation.Results reveal that the lubricating pressurization dominates the surface-initiated RCF.In addition,the initial crack angle has a significant effect on the RCF crack propagation path and the fatigue life.
