In this study, grain refining effect of Al-1.5℃ master alloy was examined on an AZ63B magnesium alloy, and the refining mechanism was studied through investigating the role of C and Fe in this process. The results sh...In this study, grain refining effect of Al-1.5℃ master alloy was examined on an AZ63B magnesium alloy, and the refining mechanism was studied through investigating the role of C and Fe in this process. The results show that addition of Al-1.5℃ master alloy leads to significant decrease of the mean grain size from about 270μm to 50μm at the center of the AZ63 alloy ingot. Grain refinement by carbon addition is mainly due to the heterogeneity nucleation on the Al-, C-, O-, Fe- and Mn-rich particles, but not constitutional undercooling caused by the carbon solute element. Fe plays an important role in the formation of the nucleating particles, but not acts as an inhibiting element.展开更多
Efforts are made to understand the timing behaviors （e.g., the jumps in the projected pulsar semimajor axis at the periastron passages） observed in the 13-year monitoring of PSR B1259-63. Planet-like objects are sug...Efforts are made to understand the timing behaviors （e.g., the jumps in the projected pulsar semimajor axis at the periastron passages） observed in the 13-year monitoring of PSR B1259-63. Planet-like objects are suggested to orbit around the Be star, which may gravitationally perturb the （probably low mass） pulsar when it passes through periastron. An accretion disk should exist outside the pulsar＇s light cylinder, which creates a spindown torque on the pulsar due to the propeller effect. The observed negative braking index and the discrepant timing residuals close to periastron could be related to the existence of a disk with a varying accretion rate. A speculation is presented that the accretion rate may increase on a long timescale in order to explain the negative braking index.展开更多
Elevated glucose metabolism triggers two primary processes that lead toβ-cell depolarization and insulin secretion:the closure of ATPsensitive K+channels via ATP-dependent mechanisms and the activation of mechanosens...Elevated glucose metabolism triggers two primary processes that lead toβ-cell depolarization and insulin secretion:the closure of ATPsensitive K+channels via ATP-dependent mechanisms and the activation of mechanosensitive channels(MSCs)due to cell swelling.However,the identity of these MSCs remains unclear.In this study,we found that TMEM63B is a stretch-activated cation channel(SAC)crucial for regulating insulin secretion in response to elevated glucose levels.TMEM63B is abundantly expressed inβ-cells,and its deletion impairs insulin secretion triggered by high glucose.High glucose levels typically increase Ca2+influx and firing frequency inβ-cells,a response largely eliminated when TMEM63B is deleted.Mechanistically,glucose metabolism induces cell swelling and activates TMEM63B,which,in turn,leads toβ-cell depolarization and insulin secretion.In conclusion,our findings demonstrate that TMEM63B is an SAC essential for regulating insulin secretion in response to elevated glucose levels.展开更多
基金supported by the National Natural Science Foundation of China(No.50171037)Natural Science Foundation of Shandong Province of China(No.Z2004F03).
文摘In this study, grain refining effect of Al-1.5℃ master alloy was examined on an AZ63B magnesium alloy, and the refining mechanism was studied through investigating the role of C and Fe in this process. The results show that addition of Al-1.5℃ master alloy leads to significant decrease of the mean grain size from about 270μm to 50μm at the center of the AZ63 alloy ingot. Grain refinement by carbon addition is mainly due to the heterogeneity nucleation on the Al-, C-, O-, Fe- and Mn-rich particles, but not constitutional undercooling caused by the carbon solute element. Fe plays an important role in the formation of the nucleating particles, but not acts as an inhibiting element.
基金Supported by the National Natural Science Foundation of China.
文摘Efforts are made to understand the timing behaviors （e.g., the jumps in the projected pulsar semimajor axis at the periastron passages） observed in the 13-year monitoring of PSR B1259-63. Planet-like objects are suggested to orbit around the Be star, which may gravitationally perturb the （probably low mass） pulsar when it passes through periastron. An accretion disk should exist outside the pulsar＇s light cylinder, which creates a spindown torque on the pulsar due to the propeller effect. The observed negative braking index and the discrepant timing residuals close to periastron could be related to the existence of a disk with a varying accretion rate. A speculation is presented that the accretion rate may increase on a long timescale in order to explain the negative braking index.
基金supported by grants from the National Natural Science Foundation of China(32330044 and 32170951 to Y.S.S.,82201615 to X.Y.T.,and 82271891 to J.C.)the Guangdong High Level Innovation Research Institute(2021B0909050004 to Y.S.S.)+2 种基金the National Key R&D Program of China(2019YFA0801603 to Y.S.S.)the Natural Science Foundation of Jiangsu Province(BK20240251 to C.Y.)the Fundamental Research Funds for the Central Universities(02141438053 to Y.S.S)。
文摘Elevated glucose metabolism triggers two primary processes that lead toβ-cell depolarization and insulin secretion:the closure of ATPsensitive K+channels via ATP-dependent mechanisms and the activation of mechanosensitive channels(MSCs)due to cell swelling.However,the identity of these MSCs remains unclear.In this study,we found that TMEM63B is a stretch-activated cation channel(SAC)crucial for regulating insulin secretion in response to elevated glucose levels.TMEM63B is abundantly expressed inβ-cells,and its deletion impairs insulin secretion triggered by high glucose.High glucose levels typically increase Ca2+influx and firing frequency inβ-cells,a response largely eliminated when TMEM63B is deleted.Mechanistically,glucose metabolism induces cell swelling and activates TMEM63B,which,in turn,leads toβ-cell depolarization and insulin secretion.In conclusion,our findings demonstrate that TMEM63B is an SAC essential for regulating insulin secretion in response to elevated glucose levels.
