The liquid phase catalytic exchange(LPCE) reaction is an effective process for heavy water detritiation and production of deuterium-depleted potable water. In the current study, hydrophobic carbon-supported platinum c...The liquid phase catalytic exchange(LPCE) reaction is an effective process for heavy water detritiation and production of deuterium-depleted potable water. In the current study, hydrophobic carbon-supported platinum catalysts(Pt/C/PTFE) with high efficiency as reported previously for LPCE were prepared and comprehensive performance evaluation method is applied to evaluate the separation behaviors of LPCE systematically. Experimental results indicate that the optimum reaction temperature of 60–80℃ and the molar feed ratio G/L of 1.5–2.5 would lead to higher separation efficiencies. As to the packing method, a random packing mode with a packing ratio of hydrophobic catalysts 0.25 is recommended. In addition, thermodynamic analysis corresponds well with experimental results under lower temperature and G/L, while the suppression of kinetic factors should not be neglected when T > 80℃ and G/L > 1.5.展开更多
Isotopic separation is of paramount importance for producing high-purity heavy hydrogen,yet the process remains hugely challenging.Here,we report on an Fe/ZSM-5 zeolite that was able to efficiently separate deuterium ...Isotopic separation is of paramount importance for producing high-purity heavy hydrogen,yet the process remains hugely challenging.Here,we report on an Fe/ZSM-5 zeolite that was able to efficiently separate deuterium from protium via chemical quantum sieving.Structural data showed that four types of Fe species were present in Fe/ZSM-5 and oligomeric Fe-O clusters in the zeolite pores were correlated directly with gas selectivity.Gas adsorption revealed that Fe-O species served as the main adsorption sites and interacted with D_(2) more strongly than with H_(2).D_(2)/H_(2)separation was exemplified using thermal desorption spectroscopy.D_(2)/H_(2) selectivity increased with Fe loading in Fe/ZSM-5 and a selectivity of 32.1 was obtained with an optimal loading of 7 wt%.The shift of desorption temperature supports the chemical affinity-based quantum sieving of D_(2)over H_(2).This study demonstrates an effective strategy for enhancing D_(2)/H_(2) separation and the high selectivity means that Fe/ZSM-5 has strong potential in hydrogen isotope separation.展开更多
Polymer-textile liner composites have potential applications in aerospace applications for reducing the abrasion damage of moving parts during operation owing to their self-lubrication,light weight,and high loading ca...Polymer-textile liner composites have potential applications in aerospace applications for reducing the abrasion damage of moving parts during operation owing to their self-lubrication,light weight,and high loading capacity.Herein,Au nanoparticles(AuNPs)are successfully loaded into the lumen of halloysite nanotubes(HNTs)to construct an HNTs‒Au peasecod core‒shell nanosystem to optimize the wear resistance of phenolic resin-based poly(p-phenylene benzobisoxazole)(PBO)/polytetrafluoroethylene(PTFE)textile composites.Transmission electron microscope(TEM)characterization reveals that the AuNPs are well-dispersed inside the HNTs,with an average diameter of 6‒9 nm.The anti-wear performance of the HNTs and Au-reinforced PBO/PTFE composites is evaluated using a pin-on-disk friction tester at 100 MPa.Evidently,the addition of HNTs‒Au induces a 27.9%decrease in the wear rate of the composites.Possible anti-wear mechanisms are proposed based on the analyzed results of the worn surface morphology and the cross-section of the tribofilm obtained by focused ion beam transmission electron microscopy.展开更多
Summary What is already known about this topic?Since May 2022,a global outbreak of mpox has emerged in more than 100 non-endemic countries.As of December 2023,over 90,000 cases had been reported.The outbreak has predo...Summary What is already known about this topic?Since May 2022,a global outbreak of mpox has emerged in more than 100 non-endemic countries.As of December 2023,over 90,000 cases had been reported.The outbreak has predominantly affected men who have sex with men(MSM),with sexual contact identified as the principal mode of transmission.What is added by this report?Since June 2023,China has faced an occurrence of mpox,predominantly affecting the MSM population.Approximately 90%of those affected reported engaging in homosexual behavior within 21 days prior to symptom onset,a trend that aligns with the global outbreak pattern.The prompt identification of cases,diligent tracing of close contacts,and the implementation of appropriate management strategies have successfully mitigated the spread of mpox virus in China.What are the implications for public health practice?We propose that mpox is transmitted locally within China.Drawing from our experiences in controlling the virus spread,it is crucial to investigate and formulate effective surveillance and educational strategies.Importantly,we must encourage high-risk populations to promptly seek medical care upon the onset of symptoms.展开更多
The high specific‐strength of glass fibers and exceptional self‐lubrication of polytetrafluoroethylene(PTFE)fibers promote the potential application of hybrid PTFE/glass fabric composites in the tribological field,b...The high specific‐strength of glass fibers and exceptional self‐lubrication of polytetrafluoroethylene(PTFE)fibers promote the potential application of hybrid PTFE/glass fabric composites in the tribological field,but their weak interfacial adhesion and inferior thermal properties significantly inhibit their tribological performance and reliability.Herein,a hybrid of polydopamine/silicon carbide/polyethyleneimine(PDA/SiC/PEI)functional coating was co‐deposited onto the hybrid PTFE/glass fabric surface through a one‐step impregnation method,leading to increased surface roughness and abundant amine groups.Tensile and peeling tests showed that this functional coating offered 47.8%enhancement in the fabric/matrix interfacial adhesion without compromising the strength of the pristine fabric.Moreover,the additional incorporation of WS_(2),and aluminum nitride(AlN)micro‐fillers contributed to the development of a high‐quality tribofilm and improved the thermal properties of fabric composites.The results of wear tests proved that the hybrid‐fabric composites,after the introduction of functional coating and micro‐fillers,exhibited outstanding tribological performance,which was attributed to the superior interfacial adhesion as well as the synergistic enhancement effects between WS2 and AlN micro‐fillers.展开更多
Recently,great effort has been devoted to prepare various reinforce fillers to improve polymer performances,but ignoring the importance of raw polymer powders which are indispensable parts of hot-pressed polymer compo...Recently,great effort has been devoted to prepare various reinforce fillers to improve polymer performances,but ignoring the importance of raw polymer powders which are indispensable parts of hot-pressed polymer composites.Herein,we engineer raw polyimide(PI)powders with the assistance of polydopamine(PDA)in aqueous solutions.After the modification,polymer powders change from hydrophobic to hydrophilic,which makes it is possible to further modification of polymer powders in liquid phase.During the curing process of modified polymer powders,the partial dehydration of the catechol groups and crosslinking of PDA via C–O–C bonds are confirmed.Based on the features of PDA,a non-destructive mixing method is utilized to realize homogeneous dispersion of multi-walled carbon nanotubes(MWCNTs)in polymer matrix.In comparison with ball milling method,this way can preserve the integrated innate structure of MWCNTs effectively.Besides,by taking full advantage of the reducing and metal-coordination capability of PDA,Cu2+is successfully loaded onto the surfaces of polymer powders.The related characterizations demonstrate that Cu2+in situ converts to metallic copper rather than copper oxide during the hot pressing process.The tribological properties of corresponding polymer composites are also studied.These results indicate that modifying polymer powders with PDA is multi-profit and presents practical application prospect.展开更多
What is already known about this topic?It is known that drug users(DUs)was brought into human immunodeficiency virus(HIV)sentinel surveillance as HIV related high-risk group since 1990s with a higher HIV antibody posi...What is already known about this topic?It is known that drug users(DUs)was brought into human immunodeficiency virus(HIV)sentinel surveillance as HIV related high-risk group since 1990s with a higher HIV antibody positive rate in the early stage.What is added by this report?This study not only showed that HIV antibody positive rate had decreased steadily since 2010 and maintained stable in past 4 years,but also showed that the proportion of the new narcotic and the mixed drug users increased since 2010 and HIV antibody positive rate of mixed abuse users increased year by year.What are the implications for public health practice?Some existing policies and strategies publicity,education and interventions require adjustments since new narcotic drug users contributed to DUs HIV infections.The challenge of HIV infection and transmission among drug users abusing both traditional and new narcotic drugs also require more attention.展开更多
基金Supported by the National Key Research and Development Program of China(2017YFE0300302)the National Natural Science Foundation of China(21503199,21406212)Key Project of Applied&Basic Research of Sichuan Province(18YYJC1594)
文摘The liquid phase catalytic exchange(LPCE) reaction is an effective process for heavy water detritiation and production of deuterium-depleted potable water. In the current study, hydrophobic carbon-supported platinum catalysts(Pt/C/PTFE) with high efficiency as reported previously for LPCE were prepared and comprehensive performance evaluation method is applied to evaluate the separation behaviors of LPCE systematically. Experimental results indicate that the optimum reaction temperature of 60–80℃ and the molar feed ratio G/L of 1.5–2.5 would lead to higher separation efficiencies. As to the packing method, a random packing mode with a packing ratio of hydrophobic catalysts 0.25 is recommended. In addition, thermodynamic analysis corresponds well with experimental results under lower temperature and G/L, while the suppression of kinetic factors should not be neglected when T > 80℃ and G/L > 1.5.
基金supported by the National Natural Science Foundation of China(22375031,22131004,U21A20330)the National Key R&D Program of China(2022YFB3805902)+2 种基金the“111”Program(B18012)Jilin Natural Science Fund for Excellent Young Scholars(20230508116RC)the Fundamental Research Funds for the Central Universities(JGPY202103,2412023YQ001)。
文摘Isotopic separation is of paramount importance for producing high-purity heavy hydrogen,yet the process remains hugely challenging.Here,we report on an Fe/ZSM-5 zeolite that was able to efficiently separate deuterium from protium via chemical quantum sieving.Structural data showed that four types of Fe species were present in Fe/ZSM-5 and oligomeric Fe-O clusters in the zeolite pores were correlated directly with gas selectivity.Gas adsorption revealed that Fe-O species served as the main adsorption sites and interacted with D_(2) more strongly than with H_(2).D_(2)/H_(2)separation was exemplified using thermal desorption spectroscopy.D_(2)/H_(2) selectivity increased with Fe loading in Fe/ZSM-5 and a selectivity of 32.1 was obtained with an optimal loading of 7 wt%.The shift of desorption temperature supports the chemical affinity-based quantum sieving of D_(2)over H_(2).This study demonstrates an effective strategy for enhancing D_(2)/H_(2) separation and the high selectivity means that Fe/ZSM-5 has strong potential in hydrogen isotope separation.
基金The authors acknowledge the financial support of the National Natural Science Foundation of China(Nos.52075523 and 52005487).
文摘Polymer-textile liner composites have potential applications in aerospace applications for reducing the abrasion damage of moving parts during operation owing to their self-lubrication,light weight,and high loading capacity.Herein,Au nanoparticles(AuNPs)are successfully loaded into the lumen of halloysite nanotubes(HNTs)to construct an HNTs‒Au peasecod core‒shell nanosystem to optimize the wear resistance of phenolic resin-based poly(p-phenylene benzobisoxazole)(PBO)/polytetrafluoroethylene(PTFE)textile composites.Transmission electron microscope(TEM)characterization reveals that the AuNPs are well-dispersed inside the HNTs,with an average diameter of 6‒9 nm.The anti-wear performance of the HNTs and Au-reinforced PBO/PTFE composites is evaluated using a pin-on-disk friction tester at 100 MPa.Evidently,the addition of HNTs‒Au induces a 27.9%decrease in the wear rate of the composites.Possible anti-wear mechanisms are proposed based on the analyzed results of the worn surface morphology and the cross-section of the tribofilm obtained by focused ion beam transmission electron microscopy.
文摘Summary What is already known about this topic?Since May 2022,a global outbreak of mpox has emerged in more than 100 non-endemic countries.As of December 2023,over 90,000 cases had been reported.The outbreak has predominantly affected men who have sex with men(MSM),with sexual contact identified as the principal mode of transmission.What is added by this report?Since June 2023,China has faced an occurrence of mpox,predominantly affecting the MSM population.Approximately 90%of those affected reported engaging in homosexual behavior within 21 days prior to symptom onset,a trend that aligns with the global outbreak pattern.The prompt identification of cases,diligent tracing of close contacts,and the implementation of appropriate management strategies have successfully mitigated the spread of mpox virus in China.What are the implications for public health practice?We propose that mpox is transmitted locally within China.Drawing from our experiences in controlling the virus spread,it is crucial to investigate and formulate effective surveillance and educational strategies.Importantly,we must encourage high-risk populations to promptly seek medical care upon the onset of symptoms.
基金The authors gratefully acknowledge the financial support from the National Natural Science Foundation of China(Grant Nos.51675252 and 51805516).
文摘The high specific‐strength of glass fibers and exceptional self‐lubrication of polytetrafluoroethylene(PTFE)fibers promote the potential application of hybrid PTFE/glass fabric composites in the tribological field,but their weak interfacial adhesion and inferior thermal properties significantly inhibit their tribological performance and reliability.Herein,a hybrid of polydopamine/silicon carbide/polyethyleneimine(PDA/SiC/PEI)functional coating was co‐deposited onto the hybrid PTFE/glass fabric surface through a one‐step impregnation method,leading to increased surface roughness and abundant amine groups.Tensile and peeling tests showed that this functional coating offered 47.8%enhancement in the fabric/matrix interfacial adhesion without compromising the strength of the pristine fabric.Moreover,the additional incorporation of WS_(2),and aluminum nitride(AlN)micro‐fillers contributed to the development of a high‐quality tribofilm and improved the thermal properties of fabric composites.The results of wear tests proved that the hybrid‐fabric composites,after the introduction of functional coating and micro‐fillers,exhibited outstanding tribological performance,which was attributed to the superior interfacial adhesion as well as the synergistic enhancement effects between WS2 and AlN micro‐fillers.
基金The authors gratefully acknowledge the financial support from the National Natural Science Foundation of China(Grant Nos.51805516 and 51675252)the CAS‘Light of West China’program.
文摘Recently,great effort has been devoted to prepare various reinforce fillers to improve polymer performances,but ignoring the importance of raw polymer powders which are indispensable parts of hot-pressed polymer composites.Herein,we engineer raw polyimide(PI)powders with the assistance of polydopamine(PDA)in aqueous solutions.After the modification,polymer powders change from hydrophobic to hydrophilic,which makes it is possible to further modification of polymer powders in liquid phase.During the curing process of modified polymer powders,the partial dehydration of the catechol groups and crosslinking of PDA via C–O–C bonds are confirmed.Based on the features of PDA,a non-destructive mixing method is utilized to realize homogeneous dispersion of multi-walled carbon nanotubes(MWCNTs)in polymer matrix.In comparison with ball milling method,this way can preserve the integrated innate structure of MWCNTs effectively.Besides,by taking full advantage of the reducing and metal-coordination capability of PDA,Cu2+is successfully loaded onto the surfaces of polymer powders.The related characterizations demonstrate that Cu2+in situ converts to metallic copper rather than copper oxide during the hot pressing process.The tribological properties of corresponding polymer composites are also studied.These results indicate that modifying polymer powders with PDA is multi-profit and presents practical application prospect.
文摘What is already known about this topic?It is known that drug users(DUs)was brought into human immunodeficiency virus(HIV)sentinel surveillance as HIV related high-risk group since 1990s with a higher HIV antibody positive rate in the early stage.What is added by this report?This study not only showed that HIV antibody positive rate had decreased steadily since 2010 and maintained stable in past 4 years,but also showed that the proportion of the new narcotic and the mixed drug users increased since 2010 and HIV antibody positive rate of mixed abuse users increased year by year.What are the implications for public health practice?Some existing policies and strategies publicity,education and interventions require adjustments since new narcotic drug users contributed to DUs HIV infections.The challenge of HIV infection and transmission among drug users abusing both traditional and new narcotic drugs also require more attention.
