AIM:To assess the efficacy and safety of parafoveal retinal massage combined with autologous whole blood cover in the treatment of refractory macular holes(MHs)and present the surgical procedure.METHODS:Patients with ...AIM:To assess the efficacy and safety of parafoveal retinal massage combined with autologous whole blood cover in the treatment of refractory macular holes(MHs)and present the surgical procedure.METHODS:Patients with giant(minimum diameter>800 pm),recurrent or persistent MHs who underwent PPV combined with parafoveal retinal massage and autologous whole blood cover using C3F8 as tamponade agent from February 2018 to May 2019 were enrolled in this retrospective study.After surgery,all patients were informed to maintain a prone position for at least 7d.Preoperative and postoperative best-corrected visual acuities(BCVAs)were compared and MH closure rate was measured as the main outcome.RESULTS:A total of 13 MH patients consisted of 6 giant MHs,4 persistent holes and 3 recurrent holes(5 men and 8 women;average age was 56.40±11.72y)were enrolled in this study.MH closure was achieved in 11 eyes by this modified surgical technique while 2 eyes failed.Revitrectomy with autologous neurosensory retinal patch transplantations was applied for those 2 patients and then both holes were closed.No intraoperative complications were observed.BCVA improved from 1.73 IogMAR to 0.74 IogMAR at 6mo postoperation.There was significant difference in BCVA before versus after the surgery(P<0.05).There were no adverse events occurred during the follow-up period.CONCLUSION:With easier surgical procedure,parafoveal retinal massage combined with autologous whole blood cover is an effective addition to the surgical options for the management of refractory MHs.展开更多
In order to describe the deformation behavior and the hot workability of equiatomic NiTi shape memory alloy (SMA) during hot deformation, Arrhenius-type constitutive equation and hot processing map of the alloy were d...In order to describe the deformation behavior and the hot workability of equiatomic NiTi shape memory alloy (SMA) during hot deformation, Arrhenius-type constitutive equation and hot processing map of the alloy were developed by hot compression tests at temperatures ranging from 500 to 1100 °C and strain rates ranging from 0.0005 to 0.5 s?1. The results show that the instability region of the hot processing map increases with the increase of deformation extent. The instability occurs in the low and high temperature regions. The instability region presents the adiabatic shear bands at low temperatures, but it exhibits the abnormal growth of the grains at high temperatures. Consequently, it is necessary to avoid processing the equiatomic NiTi SMA in these regions. It is preferable to process the NiTi SMA at the temperatures ranging from 750 to 900 °C.展开更多
Purpose:This study aimed to investigate the current status of self-differentiation and professional adaptability among undergraduate nursing students,to analyze the relationship between these two variables,and to prov...Purpose:This study aimed to investigate the current status of self-differentiation and professional adaptability among undergraduate nursing students,to analyze the relationship between these two variables,and to provide recommendations for nursing educators.Methods:A total of 341 nursing undergraduate students at the University of South China were investigated using the Differentiation of Self Inventory and the Professional Adaptability Scale for college students.Results:The mean scores of self-differentiation and professional adaptability were 3.70±0.60 and 2.87±0.37,respectively,and the two variables were positively correlated(P<0.01).Conclusion:The level of self-differentiation of undergraduate nursing studentsaffects their professional adaptability.Nursing educators should consider the characteristics of self-differentiation of undergraduate nursing students in developing measures to improve their professional adaptability.展开更多
Flame retardants play a crucial role in improving theflame retardant properties of polymer materials.In recent years,environmental problems caused byflame retar-dants have attracted widespread attention.It is urgent to ...Flame retardants play a crucial role in improving theflame retardant properties of polymer materials.In recent years,environmental problems caused byflame retar-dants have attracted widespread attention.It is urgent to use green and effective methods to prepareflame retardant polymers.Bioinspired nanocomposites with lay-ered structures seem to provide effective ideas,but in general,their hydrophilic raw materials limit their applications in certainfields.Here,we prepared biomimetic composites with a layered“brick-and-mortar”structure by gravity-induced depo-sition using polyimide as the polymer matrix and montmorillonite(MMT)as thefiller.The well-arranged structures of the composite material could isolate oxygen and prevent combustible gases from escaping.The gas barrier performance has been greatly improved,in which the water vapor transmission rate and the oxygen trans-mission rate decreased by 99.18%and three orders of magnitude,respectively.Theflame retardant performance has also been improved,and its limiting oxygen index can reach 67.9%.The polyimide matrix can be converted to water-insoluble by ther-mal imidization of water-soluble poly(amic acid)salt precursors,which endows the composites with low hygroscopicity.The coating containing MMT can protect against polyurethane(PU)foam fromfire.During the conical calorimetric test,the coated sample self-extinguished,and the peak heat release rate,total heat release,and total smoke production are significantly decreased by 53.39%,40.69%,and 53.03%,respectively.Taking advantage of these properties,this work utilizes a facile method to prepare biomimetic composites with low moisture absorption,excellent gas barrier properties,andflame retardancy,which have great application potential.展开更多
A diamine(WuFDA) containing vertical rigid non-planar conjugated fluorene moiety and low polarizability group(C―F)was designed and synthesized through three steps of reactions(halogenated reaction, Suzuki coupling re...A diamine(WuFDA) containing vertical rigid non-planar conjugated fluorene moiety and low polarizability group(C―F)was designed and synthesized through three steps of reactions(halogenated reaction, Suzuki coupling reaction, and reduction reaction).Four kinds of high performance functional polyimides(WuFPI-6 F, WuFPI-BP, WuFPI-BT, and WuFPI-PM) were thus prepared by the condensation polymerization of WuFDA with four commercial dianhydride 6 FDA, BPDA, BTDA, and PMDA, respectively. The polyimides exhibited low dielectric constant, excellent thermal stability, outstanding solubility, good film-forming property, and mechanical properties. The dielectric constants of the polyimides were in the range of 2.28-2.88(f = 10~4 Hz). The 5% weight-loss temperatures(Td 5%)in nitrogen were in the range of 555-584 °C, and the glass transition temperatures(T_g) were in the range of 408-448 °C. The weight loss of WuFPI-BP maintaining at 450 and 500 °C for half an hour was only 0.33% and 1.26%, respectively. All the WuFPIs could be dissolved in almost all organic solvents, even chloroform. The tensile strength and tensile modulus of these films were in the ranges of 78.6-85.7 MPa and 3.1-3.2 GPa, respectively. In addition, the polyimides displayed light color with special fluorescent and resistive switching(ON-OFF) characteristics; the maximum fluorescence emission was observed at 422-424 nm in NMP solution and at 470-548 nm in film state. The memory devices with the configuration of indium tin oxide/WuFPIs/aluminum(ITO/WuFPIs/Al) exhibited distinct volatile memory characteristics of static random access memory(SRAM), with an ON/OFF current ratio of 10~5-10~6. These functional polyimides showed attractive potential applications in the field of high performance flexible polymer photoelectronic devices or polymer memory devices.展开更多
High-performance low-k and low-loss circuit materials are urgently needed in the field of microelectronics due to the upcoming FifthGeneration Mobile Communications Technology(5 G Technology).Herein,a facile design st...High-performance low-k and low-loss circuit materials are urgently needed in the field of microelectronics due to the upcoming FifthGeneration Mobile Communications Technology(5 G Technology).Herein,a facile design strategy for non-fluorinated intrinsic low-k and low-loss polyimides is reported by fully considering the secondary relaxation behaviors of the polymer chains.A new amorphous non-fluorinated polymer(TmBPPA)with a k value of 2.23 and a loss tangent lower than 3.94×10^-3 at 104 Hz has been designed and synthesized,which to the best of our knowledge is the lowest value amongst the non-fluorinated and non-porous polymers reported in literature.Meanwhile,TmBPPA exhibits excellent overall properties,such as excellent thermostability,good mechanical properties,low moisture absorption,and high bonding strength.As high-performance flexible circuit materials,all these characteristics are highly expected to meet the present and future demands for high density,high speed,and high frequency electronic circuit used in 5 G wireless networks.展开更多
A polymer （poly（9,10）anthracenevinylene-alt-4,4＇-（9,9-bis（4-（4＇-（1,2,2＇-triphenyviny）phenoxy）butyl）-9H- fluorene-2,7-diyl） dibenzaldehyde）, P1） was successfully synthesized through the Wittig-Horner re...A polymer （poly（9,10）anthracenevinylene-alt-4,4＇-（9,9-bis（4-（4＇-（1,2,2＇-triphenyviny）phenoxy）butyl）-9H- fluorene-2,7-diyl） dibenzaldehyde）, P1） was successfully synthesized through the Wittig-Horner reaction by employing fluorene and 9,10-distyrylanthracene moieties as building blocks for backbone and tetraphenylethenes as pendant groups. Photophysical and thermal properties of the resulting polymeric emitter were fully characterized by ultraviolet-visible （UV- Vis） absorption and photoluminescence （PL） spectra, thermogravimetric analysis （TGA） and differential scanning calorimetry （DSC）. While P1 emits an orange-light centered at 567 nm in dilute tetrahydrofuran （THF） solution, the solid powder of the polymer exhibits strong yellow emission peaked at 541 nm. It is also found that the as-synthesized polymer shows unique property of aggregation-enhanced emission （AEE）. In addition, P1 possesses high thermal stability with a decomposition temperature （Td,5%） of 430 ℃ and high morphological stability with a glass transition temperature （Tg） of 171℃. Under the stimulus of mechanical force, the emission of P1 can be changed from yellow to red （△λmax = 61 rim）, showing a remarkable mechanochromism. The results from XRD analysis suggest that such mechanochromic phenomenonof PI is probably caused by the destruction of crystalline structure, which leads to the conformational planarization of the distyrylanthracene moieties forming by the polymerization and the increase of molecular conjugation of the backbone.展开更多
A new macromolecular surface modifier, a copolymer of lauryl methacrylate （LMA） and poly（ethylene glycol） methyl methacrylate （PEGMA）, was synthesized through free radical polymerization. The copolymer was chara...A new macromolecular surface modifier, a copolymer of lauryl methacrylate （LMA） and poly（ethylene glycol） methyl methacrylate （PEGMA）, was synthesized through free radical polymerization. The copolymer was characterized by nuclear magnetic resonance spectrum （lH-NMR） and thermogravimetric analysis （TGA）. The copolymer was used to blend with polyethylene. The binary blends have been characterized by attenuated total reflection/Fourier transform infrared （ATR- FTIR）, contact-angle measurements （CDA） and scanning electron microscopy （SEM）. The results indicated that poly（ethylene glycol） methyl methacrylate-co-lauryl methacrylate （PEGMA-co-LMA） could diffuse preferably onto the surface of the polyethylene （PE） film, and thus can be used as an efficient surface modifier for PE.展开更多
文摘AIM:To assess the efficacy and safety of parafoveal retinal massage combined with autologous whole blood cover in the treatment of refractory macular holes(MHs)and present the surgical procedure.METHODS:Patients with giant(minimum diameter>800 pm),recurrent or persistent MHs who underwent PPV combined with parafoveal retinal massage and autologous whole blood cover using C3F8 as tamponade agent from February 2018 to May 2019 were enrolled in this retrospective study.After surgery,all patients were informed to maintain a prone position for at least 7d.Preoperative and postoperative best-corrected visual acuities(BCVAs)were compared and MH closure rate was measured as the main outcome.RESULTS:A total of 13 MH patients consisted of 6 giant MHs,4 persistent holes and 3 recurrent holes(5 men and 8 women;average age was 56.40±11.72y)were enrolled in this study.MH closure was achieved in 11 eyes by this modified surgical technique while 2 eyes failed.Revitrectomy with autologous neurosensory retinal patch transplantations was applied for those 2 patients and then both holes were closed.No intraoperative complications were observed.BCVA improved from 1.73 IogMAR to 0.74 IogMAR at 6mo postoperation.There was significant difference in BCVA before versus after the surgery(P<0.05).There were no adverse events occurred during the follow-up period.CONCLUSION:With easier surgical procedure,parafoveal retinal massage combined with autologous whole blood cover is an effective addition to the surgical options for the management of refractory MHs.
基金Projects(51305091,51305092,51475101)supported by the National Natural Science Foundation of ChinaProject(20132304120025)supported by the Specialized Research Fund for the Doctoral Program of Higher Education,China
文摘In order to describe the deformation behavior and the hot workability of equiatomic NiTi shape memory alloy (SMA) during hot deformation, Arrhenius-type constitutive equation and hot processing map of the alloy were developed by hot compression tests at temperatures ranging from 500 to 1100 °C and strain rates ranging from 0.0005 to 0.5 s?1. The results show that the instability region of the hot processing map increases with the increase of deformation extent. The instability occurs in the low and high temperature regions. The instability region presents the adiabatic shear bands at low temperatures, but it exhibits the abnormal growth of the grains at high temperatures. Consequently, it is necessary to avoid processing the equiatomic NiTi SMA in these regions. It is preferable to process the NiTi SMA at the temperatures ranging from 750 to 900 °C.
基金We thank all the students who participated in our study.
文摘Purpose:This study aimed to investigate the current status of self-differentiation and professional adaptability among undergraduate nursing students,to analyze the relationship between these two variables,and to provide recommendations for nursing educators.Methods:A total of 341 nursing undergraduate students at the University of South China were investigated using the Differentiation of Self Inventory and the Professional Adaptability Scale for college students.Results:The mean scores of self-differentiation and professional adaptability were 3.70±0.60 and 2.87±0.37,respectively,and the two variables were positively correlated(P<0.01).Conclusion:The level of self-differentiation of undergraduate nursing studentsaffects their professional adaptability.Nursing educators should consider the characteristics of self-differentiation of undergraduate nursing students in developing measures to improve their professional adaptability.
基金Ministry of Science and Technology,Grant/Award Number:2022YFB3806601National Natural Science Foundation of China,Grant/Award Numbers:U20A20255,51873239,52103022,52203286+2 种基金Guangdong Provincial Department of Science and Technology,Grant/Award Numbers:2020B010182001,2020B010179001,2021A1515010664,2019B040401002Fellowship of China Postdoctoral Science Foundation,Grant/Award Number:2022M723572Guangxi Provincial Department of Science and Technology,Grant/Award Number:GLESI-KFKY2301013。
文摘Flame retardants play a crucial role in improving theflame retardant properties of polymer materials.In recent years,environmental problems caused byflame retar-dants have attracted widespread attention.It is urgent to use green and effective methods to prepareflame retardant polymers.Bioinspired nanocomposites with lay-ered structures seem to provide effective ideas,but in general,their hydrophilic raw materials limit their applications in certainfields.Here,we prepared biomimetic composites with a layered“brick-and-mortar”structure by gravity-induced depo-sition using polyimide as the polymer matrix and montmorillonite(MMT)as thefiller.The well-arranged structures of the composite material could isolate oxygen and prevent combustible gases from escaping.The gas barrier performance has been greatly improved,in which the water vapor transmission rate and the oxygen trans-mission rate decreased by 99.18%and three orders of magnitude,respectively.Theflame retardant performance has also been improved,and its limiting oxygen index can reach 67.9%.The polyimide matrix can be converted to water-insoluble by ther-mal imidization of water-soluble poly(amic acid)salt precursors,which endows the composites with low hygroscopicity.The coating containing MMT can protect against polyurethane(PU)foam fromfire.During the conical calorimetric test,the coated sample self-extinguished,and the peak heat release rate,total heat release,and total smoke production are significantly decreased by 53.39%,40.69%,and 53.03%,respectively.Taking advantage of these properties,this work utilizes a facile method to prepare biomimetic composites with low moisture absorption,excellent gas barrier properties,andflame retardancy,which have great application potential.
基金financial support by the National 973 Program of China (No. 2014CB643605)the National Natural Science Foundation of China (Nos. 51373204 and 51873239)+3 种基金the Science and Technology Project of Guangdong Province (Nos. 2015B090915003 and 2015B090913003)the China Postdoctoral Science Foundation (No. 2017M612801)the Leading Scientific, Technical and Innovation Talents of Guangdong Special Support Program (No. 2016TX03C295)the Fundamental Research Funds for the Central Universities (No. 161gzd08)
文摘A diamine(WuFDA) containing vertical rigid non-planar conjugated fluorene moiety and low polarizability group(C―F)was designed and synthesized through three steps of reactions(halogenated reaction, Suzuki coupling reaction, and reduction reaction).Four kinds of high performance functional polyimides(WuFPI-6 F, WuFPI-BP, WuFPI-BT, and WuFPI-PM) were thus prepared by the condensation polymerization of WuFDA with four commercial dianhydride 6 FDA, BPDA, BTDA, and PMDA, respectively. The polyimides exhibited low dielectric constant, excellent thermal stability, outstanding solubility, good film-forming property, and mechanical properties. The dielectric constants of the polyimides were in the range of 2.28-2.88(f = 10~4 Hz). The 5% weight-loss temperatures(Td 5%)in nitrogen were in the range of 555-584 °C, and the glass transition temperatures(T_g) were in the range of 408-448 °C. The weight loss of WuFPI-BP maintaining at 450 and 500 °C for half an hour was only 0.33% and 1.26%, respectively. All the WuFPIs could be dissolved in almost all organic solvents, even chloroform. The tensile strength and tensile modulus of these films were in the ranges of 78.6-85.7 MPa and 3.1-3.2 GPa, respectively. In addition, the polyimides displayed light color with special fluorescent and resistive switching(ON-OFF) characteristics; the maximum fluorescence emission was observed at 422-424 nm in NMP solution and at 470-548 nm in film state. The memory devices with the configuration of indium tin oxide/WuFPIs/aluminum(ITO/WuFPIs/Al) exhibited distinct volatile memory characteristics of static random access memory(SRAM), with an ON/OFF current ratio of 10~5-10~6. These functional polyimides showed attractive potential applications in the field of high performance flexible polymer photoelectronic devices or polymer memory devices.
基金finincially supported by the National Natural Science Foundation of China (Nos. 51373204 and 51873239)the National 973 Program of China (No. 2014CB643605)+3 种基金the Science and Technology Project of Guangdong Province (Nos. 2015B090915003 and 2015B090913003)the Leading Scientific, Technical and Innovation Talents of Guangdong Special Support Program (No. 2016TX03C295)the China Postdoctoral Science Foundation (No. 2017M612801)the Fundamental Research Funds of Sun Yat-sen University
文摘High-performance low-k and low-loss circuit materials are urgently needed in the field of microelectronics due to the upcoming FifthGeneration Mobile Communications Technology(5 G Technology).Herein,a facile design strategy for non-fluorinated intrinsic low-k and low-loss polyimides is reported by fully considering the secondary relaxation behaviors of the polymer chains.A new amorphous non-fluorinated polymer(TmBPPA)with a k value of 2.23 and a loss tangent lower than 3.94×10^-3 at 104 Hz has been designed and synthesized,which to the best of our knowledge is the lowest value amongst the non-fluorinated and non-porous polymers reported in literature.Meanwhile,TmBPPA exhibits excellent overall properties,such as excellent thermostability,good mechanical properties,low moisture absorption,and high bonding strength.As high-performance flexible circuit materials,all these characteristics are highly expected to meet the present and future demands for high density,high speed,and high frequency electronic circuit used in 5 G wireless networks.
基金financially supported by the National Natural Science Foundation of China(Nos.51473185,51603233 and 21672267)863 Program(No.SS2015AA031701)+1 种基金the Fundamental Research Funds for the Central UniversitiesGuangdong Science and Technology Plan(Nos.2015B090913003 and 2015B090915003)
文摘A polymer （poly（9,10）anthracenevinylene-alt-4,4＇-（9,9-bis（4-（4＇-（1,2,2＇-triphenyviny）phenoxy）butyl）-9H- fluorene-2,7-diyl） dibenzaldehyde）, P1） was successfully synthesized through the Wittig-Horner reaction by employing fluorene and 9,10-distyrylanthracene moieties as building blocks for backbone and tetraphenylethenes as pendant groups. Photophysical and thermal properties of the resulting polymeric emitter were fully characterized by ultraviolet-visible （UV- Vis） absorption and photoluminescence （PL） spectra, thermogravimetric analysis （TGA） and differential scanning calorimetry （DSC）. While P1 emits an orange-light centered at 567 nm in dilute tetrahydrofuran （THF） solution, the solid powder of the polymer exhibits strong yellow emission peaked at 541 nm. It is also found that the as-synthesized polymer shows unique property of aggregation-enhanced emission （AEE）. In addition, P1 possesses high thermal stability with a decomposition temperature （Td,5%） of 430 ℃ and high morphological stability with a glass transition temperature （Tg） of 171℃. Under the stimulus of mechanical force, the emission of P1 can be changed from yellow to red （△λmax = 61 rim）, showing a remarkable mechanochromism. The results from XRD analysis suggest that such mechanochromic phenomenonof PI is probably caused by the destruction of crystalline structure, which leads to the conformational planarization of the distyrylanthracene moieties forming by the polymerization and the increase of molecular conjugation of the backbone.
基金supported by the National Natural Science Foundation of China (Nos. 51173214, J1103305)Department of Education of Guangdong Province (2012KJCX0005)Science and Technology Bureau of Guangzhou
文摘A new macromolecular surface modifier, a copolymer of lauryl methacrylate （LMA） and poly（ethylene glycol） methyl methacrylate （PEGMA）, was synthesized through free radical polymerization. The copolymer was characterized by nuclear magnetic resonance spectrum （lH-NMR） and thermogravimetric analysis （TGA）. The copolymer was used to blend with polyethylene. The binary blends have been characterized by attenuated total reflection/Fourier transform infrared （ATR- FTIR）, contact-angle measurements （CDA） and scanning electron microscopy （SEM）. The results indicated that poly（ethylene glycol） methyl methacrylate-co-lauryl methacrylate （PEGMA-co-LMA） could diffuse preferably onto the surface of the polyethylene （PE） film, and thus can be used as an efficient surface modifier for PE.
