Poly(vinylidene fluoride)(PVDF)foam has received widespread attention due to its high strength,and excellent combination of flame-retardancy,antibacterial performance,and chemical stability.However,the foaming ability...Poly(vinylidene fluoride)(PVDF)foam has received widespread attention due to its high strength,and excellent combination of flame-retardancy,antibacterial performance,and chemical stability.However,the foaming ability of conventional PvDF is severely limited by its rapid crystallization kinetics and poor melt strength.Although ultra-high molecular weight PVDF(H-PVDF)theoretically offers prolonged melt elasticity favorable for foaming,the extremely high melt viscosity poses substantial processing challenges,and its foaming behavior has remained largely unexplored.To address these issues,this study proposes a novel fabrication strategy combining solvent casting with microcellular foaming to prepare H-PVDF foams.Dynamic mechanical analysis and differential scanning calorimetry reveal that extensive chain entanglements in H-PVDF impose constraints on crystallization and significantly enhance melt strength.By tuning the processing parameters,the distinctive foaming be-havior of H-PVDF under various conditions is systematically elucidated.Remarkably,a record-high expansion ratio of 55.6-fold is achieved,ac-companied by a highly uniform and fine cellular structure.The resulting H-PVDF foams exhibit a low thermal conductivity of 31.8 mW·m^(-1).K^(-1),while retaining excellent compressive strength,flame-retardancy,and hydrophobicity.These outstanding properties highlight the great potential of H-PVDF foams as the thermal insulation materials for applications in aerospace,energy infrastructure,and other extreme environments.展开更多
Background:Critical patients with the coronavirus disease 2019(COVID-19),even those whose nucleic acid test results had turned negative and those receiving maximal medical support,have been noted to progress to irreve...Background:Critical patients with the coronavirus disease 2019(COVID-19),even those whose nucleic acid test results had turned negative and those receiving maximal medical support,have been noted to progress to irreversible fatal respiratory failure.Lung transplantation(LT)as the sole therapy for end-stage pulmonary fibrosis related to acute respiratory distress syndrome has been considered as the ultimate rescue therapy for these patients.Methods:From February 10 to March 10,2020,three male patients were urgently assessed and listed for transplantation.After conducting a full ethical review and after obtaining assent from the family of the patients,we performed three LT procedures for COVID-19 patients with illness durations of more than one month and extremely high sequential organ failure assessment scores.Results:Two of the three recipients survived post-LT and started participating in a rehabilitation program.Pearls of the LT team collaboration and perioperative logistics were summarized and continually improved.The pathological results of the explanted lungs were concordant with the critical clinical manifestation,and provided insight towards better understanding of the disease.Government health affair systems,virology detection tools,and modern communication technology all play key roles towards the survival of the patients and their rehabilitation.Conclusions:LT can be performed in end-stage patients with respiratory failure due to COVID-19-related pulmonary fibrosis.If confirmed positive-turned-negative virology status without organ dysfunction that could contraindicate LT,LT provided the final option for these patients to avoid certain death,with proper protection of transplant surgeons and medical staffs.By ensuring instant seamless care for both patients and medical teams,the goal of reducing the mortality rate and salvaging the lives of patients with COVID-19 can be attained.展开更多
基金supported by the National Natural Science Foundation of China(No.52175341)Shandong Provincial Natural Science Foundation(No.ZR2022JQ24)+2 种基金Funding Project of Jinan City's New Twenty Items for Colleges and Universities(No.202333038)Excellent Young Team Project of Central Universities(No.2023QNTD002)Qingdao Key Technology Research and Industrialization Demonstration Project(No.24-1-2-qljh-10-gx).
文摘Poly(vinylidene fluoride)(PVDF)foam has received widespread attention due to its high strength,and excellent combination of flame-retardancy,antibacterial performance,and chemical stability.However,the foaming ability of conventional PvDF is severely limited by its rapid crystallization kinetics and poor melt strength.Although ultra-high molecular weight PVDF(H-PVDF)theoretically offers prolonged melt elasticity favorable for foaming,the extremely high melt viscosity poses substantial processing challenges,and its foaming behavior has remained largely unexplored.To address these issues,this study proposes a novel fabrication strategy combining solvent casting with microcellular foaming to prepare H-PVDF foams.Dynamic mechanical analysis and differential scanning calorimetry reveal that extensive chain entanglements in H-PVDF impose constraints on crystallization and significantly enhance melt strength.By tuning the processing parameters,the distinctive foaming be-havior of H-PVDF under various conditions is systematically elucidated.Remarkably,a record-high expansion ratio of 55.6-fold is achieved,ac-companied by a highly uniform and fine cellular structure.The resulting H-PVDF foams exhibit a low thermal conductivity of 31.8 mW·m^(-1).K^(-1),while retaining excellent compressive strength,flame-retardancy,and hydrophobicity.These outstanding properties highlight the great potential of H-PVDF foams as the thermal insulation materials for applications in aerospace,energy infrastructure,and other extreme environments.
基金This study was supported by grants from the Chen Jingyu team of“Sanming Project of Medicine”in Shenzhen(No.SZSM201812058)the Foundation for Special Projects of COVID-19 Prevention and Control in Wuxi City.
文摘Background:Critical patients with the coronavirus disease 2019(COVID-19),even those whose nucleic acid test results had turned negative and those receiving maximal medical support,have been noted to progress to irreversible fatal respiratory failure.Lung transplantation(LT)as the sole therapy for end-stage pulmonary fibrosis related to acute respiratory distress syndrome has been considered as the ultimate rescue therapy for these patients.Methods:From February 10 to March 10,2020,three male patients were urgently assessed and listed for transplantation.After conducting a full ethical review and after obtaining assent from the family of the patients,we performed three LT procedures for COVID-19 patients with illness durations of more than one month and extremely high sequential organ failure assessment scores.Results:Two of the three recipients survived post-LT and started participating in a rehabilitation program.Pearls of the LT team collaboration and perioperative logistics were summarized and continually improved.The pathological results of the explanted lungs were concordant with the critical clinical manifestation,and provided insight towards better understanding of the disease.Government health affair systems,virology detection tools,and modern communication technology all play key roles towards the survival of the patients and their rehabilitation.Conclusions:LT can be performed in end-stage patients with respiratory failure due to COVID-19-related pulmonary fibrosis.If confirmed positive-turned-negative virology status without organ dysfunction that could contraindicate LT,LT provided the final option for these patients to avoid certain death,with proper protection of transplant surgeons and medical staffs.By ensuring instant seamless care for both patients and medical teams,the goal of reducing the mortality rate and salvaging the lives of patients with COVID-19 can be attained.
