Stem cell research is a promising area of transplantation and regenerative medicine with tremendous potential for improving the clinical treatment and diagnostic options across a variety of conditions and enhancing un...Stem cell research is a promising area of transplantation and regenerative medicine with tremendous potential for improving the clinical treatment and diagnostic options across a variety of conditions and enhancing understanding of human development.Over the past few decades,mesenchymal stem cell(MSCs)studies have exponentially increased with a promising outcome.However,regardless of the huge investment and the research attention given to stem cell research,FDA approval for clinical use is still lacking.Amid the challenges confronting stem cell research as a cellbased product,there appears to be evidence of superior effect and heightened potential success in its expressed vesicles,exosomes,as cell-free products.In addition to their highly desirable intrinsic biologically unique structural,compositional,and morphological characteristics,as well as predominant physiochemical stability and biocompatibility properties,exosomes can also be altered to enhance their therapeutic capability or diagnostic imaging potential via physical,chemical,and biological modification approaches.More importantly,the powerful therapeutic potential and superior biological functions of exosomes,particularly,regarding engineered exosomes as cell-free products,and their utilization in a new generation of nanomedicine treatment,vaccination,and diagnosis platforms,brings hope of a change in the near future.This viewpoint discusses the trend of stem cell research and why stem cell-derived exosomes could be the game-changer.展开更多
Multi-band microwave absorption is becoming ubiquitous owing to the increasingly complex electromagnetic environment driven by the diversity of electronic devices.However,research on efficient electromagnetic absorber...Multi-band microwave absorption is becoming ubiquitous owing to the increasingly complex electromagnetic environment driven by the diversity of electronic devices.However,research on efficient electromagnetic absorbers applicable in both centimeter-wave and millimeter-wave bands to address the electromagnetic interference in 5G networks is highly challenging.In this study,Fe_(x)(Co_(y)Ni_(1-y))_(100-x)particles with two phases(face-centered cubic(FCC)and hexagonal close-packed(HCP))were synthesized and were found to exhibit excellent electromagnetic wave absorption.HCP phase with high magnetocrystalline anisotropy was introduced into FCC phase Fe_(x)(Co_(y)Ni_(1-y))_(100-x),resulting in natural resonances in multi-band frequency.Prominent microwave absorption properties in ultra-wide bandwidth ranging from 6.9 to 39.5 GHz were obtained.The maximum reflection loss(RL)of the Fe_(23)(Co_(0.5)Ni_(0.5))77 composite film reached-50 dB.Such a remarkable absorption performance is attributed to the synergetic effects of the multiple natural resonances generated by the coexistence of HCP and FCC phases in Fe23(Co0.5Ni0.5)77.Overall,this work is promising for the future design of high-performance microwave absorbing materials in a wide bandwidth.展开更多
Although many dielectric polymers exhibit high energy storage density(Ue)with enhanced dipolar polarization at room temperature,the substantially increased electric conduction loss at high applied electric fields and ...Although many dielectric polymers exhibit high energy storage density(Ue)with enhanced dipolar polarization at room temperature,the substantially increased electric conduction loss at high applied electric fields and high temperatures remains a great challenge.Here,we report a strategy that high contents of medium-polar ester group and end-group(St)modification are introduced into a biode-gradable polymer polylactic acid(PLA)to synergistically reduce the loss and enhance Ue and charge-discharge efficiency(h).The resultant St-modified PLA polymer(PLA-St)exhibits an Ue of 6.5 J/cm^(3)with an ultra-high h(95.4%),far outperforming the best reported dielectric polymers.It is worth noting that the modified molecular structures can generate deep trap centers and restrict the local dipole motions in the polymer,which are responsible for the reduction of conduction loss and improvements in high-temperature capacitive performance.In addition,the PLA-St polymer shows intrinsically excellent self-healing ability and cyclic stability surviving over 500000 charge-discharge cycles.This work offers an efficient route to next-generation eco-friendly dielectric polymers with high energy density,low loss,and long-term stability.展开更多
Dielectrics used for energy storage are highly desired for power electronics and pulse power applications and the polymer capacitors are the main commercial ones available.The development of flexible electronics and w...Dielectrics used for energy storage are highly desired for power electronics and pulse power applications and the polymer capacitors are the main commercial ones available.The development of flexible electronics and wearable devices require the relative materials being flexible.Besides,high temperature resistance is also desired because of the rising demand for high power devices and large electricity under elevated temperature.The polymer dielectrics for polymer capacitors are flexible but with relatively low working temperature normally less than 100℃.Therefore,fabricating a dielectric material to satisfy the flexibility and high working temperature simultaneously is still a great challenge.Here we propose one solution by demonstrating a hand-exfoliated fluorophlogopite film with micrometer scale thickness.Among which,the mica film with a thickness of around 10μm(Mica-10)exhibits the inorganic-like temperature stability even polymer-like flexibility.From 25℃to 200℃,Mica-10 has an energy density of around 11.27 J/cm^(3)with a variation within 2%,accompanied by a charge-discharge efficiency of around 95%at an electric field of 500 MV/m.Meanwhile,the thin thickness makes Mica-10 flexible,enabling its excellent flexibility and durability.This work revives the traditional material,mica,providing a way for high-temperature energy storage applications.展开更多
In this work,the(1-x)CaWO_(4)-xNa_(2)WO_(4)(x=0.1,0.2,denoted as 0.9CW-0.1NW and 0.8CW-0.2NW,respectively)ultralow-loss microwave dielectric ceramics were prepared via solid-state reaction method.Using low melting-poi...In this work,the(1-x)CaWO_(4)-xNa_(2)WO_(4)(x=0.1,0.2,denoted as 0.9CW-0.1NW and 0.8CW-0.2NW,respectively)ultralow-loss microwave dielectric ceramics were prepared via solid-state reaction method.Using low melting-point Na_(2)WO_(4) as sintering aid to prepare CaW_(O4)eNa_(2)WO_(4) composite ceramics,the sintering temperature of CaWO_(4) was successfully reduced while maintaining excellent microwave performance.The optimal microwave dielectric properties have been achieved at 900C for 0.9CW-0.1NW ceramic:εr=9.0,Q×f=105660 GHz,tandδ=1.1×10^(-4)and tf=35.4 ppm/℃ at a frequency of 12.0 GHz.For the 0.8CW-0.2NW ceramic,the optimal microwave dielectric properties have been obtained at 740C,withεr=8.5,Q×f=97014 GHz,tandδ=1.2×10^(-4)and tf=37.4 ppm/℃ at a frequency of 11.8 GHz.In summary,both composite ceramics exhibit low sintering temperatures,excellent dielectric properties and chemical compatibility with the Ag electrode.The findings of this study provide an effective approach to prepare novel composite ceramics as promising candidates for LTCC applications.展开更多
文摘Stem cell research is a promising area of transplantation and regenerative medicine with tremendous potential for improving the clinical treatment and diagnostic options across a variety of conditions and enhancing understanding of human development.Over the past few decades,mesenchymal stem cell(MSCs)studies have exponentially increased with a promising outcome.However,regardless of the huge investment and the research attention given to stem cell research,FDA approval for clinical use is still lacking.Amid the challenges confronting stem cell research as a cellbased product,there appears to be evidence of superior effect and heightened potential success in its expressed vesicles,exosomes,as cell-free products.In addition to their highly desirable intrinsic biologically unique structural,compositional,and morphological characteristics,as well as predominant physiochemical stability and biocompatibility properties,exosomes can also be altered to enhance their therapeutic capability or diagnostic imaging potential via physical,chemical,and biological modification approaches.More importantly,the powerful therapeutic potential and superior biological functions of exosomes,particularly,regarding engineered exosomes as cell-free products,and their utilization in a new generation of nanomedicine treatment,vaccination,and diagnosis platforms,brings hope of a change in the near future.This viewpoint discusses the trend of stem cell research and why stem cell-derived exosomes could be the game-changer.
基金This work was supported by Key Area Research Plan of Guangdong(No.2020B010176001)Shenzhen Science and Technology Program(Nos.KQTD20180411143514543 and JCYJ 20180504165831308)Shenzhen DRC project[2018]1433.
文摘Multi-band microwave absorption is becoming ubiquitous owing to the increasingly complex electromagnetic environment driven by the diversity of electronic devices.However,research on efficient electromagnetic absorbers applicable in both centimeter-wave and millimeter-wave bands to address the electromagnetic interference in 5G networks is highly challenging.In this study,Fe_(x)(Co_(y)Ni_(1-y))_(100-x)particles with two phases(face-centered cubic(FCC)and hexagonal close-packed(HCP))were synthesized and were found to exhibit excellent electromagnetic wave absorption.HCP phase with high magnetocrystalline anisotropy was introduced into FCC phase Fe_(x)(Co_(y)Ni_(1-y))_(100-x),resulting in natural resonances in multi-band frequency.Prominent microwave absorption properties in ultra-wide bandwidth ranging from 6.9 to 39.5 GHz were obtained.The maximum reflection loss(RL)of the Fe_(23)(Co_(0.5)Ni_(0.5))77 composite film reached-50 dB.Such a remarkable absorption performance is attributed to the synergetic effects of the multiple natural resonances generated by the coexistence of HCP and FCC phases in Fe23(Co0.5Ni0.5)77.Overall,this work is promising for the future design of high-performance microwave absorbing materials in a wide bandwidth.
基金supported by National Key Research&Development Program(No.2021YFB3800603)National Natural Science Foundation of China(No.92066208)+1 种基金Shenzhen Science and Technology Program(Nos.KQTD20180411143514543,JCYJ20180504165831308)Guangdong Natural Science Foundation(No.2020A1515011043).
文摘Although many dielectric polymers exhibit high energy storage density(Ue)with enhanced dipolar polarization at room temperature,the substantially increased electric conduction loss at high applied electric fields and high temperatures remains a great challenge.Here,we report a strategy that high contents of medium-polar ester group and end-group(St)modification are introduced into a biode-gradable polymer polylactic acid(PLA)to synergistically reduce the loss and enhance Ue and charge-discharge efficiency(h).The resultant St-modified PLA polymer(PLA-St)exhibits an Ue of 6.5 J/cm^(3)with an ultra-high h(95.4%),far outperforming the best reported dielectric polymers.It is worth noting that the modified molecular structures can generate deep trap centers and restrict the local dipole motions in the polymer,which are responsible for the reduction of conduction loss and improvements in high-temperature capacitive performance.In addition,the PLA-St polymer shows intrinsically excellent self-healing ability and cyclic stability surviving over 500000 charge-discharge cycles.This work offers an efficient route to next-generation eco-friendly dielectric polymers with high energy density,low loss,and long-term stability.
基金supported by the Shenzhen Science and Technology Program(KQTD20180411143514543,JCYJ20220818100613029,and JSGGZD20220822095603006)the Guangdong Basic and Applied Basic Research Foundation(2021A1515110634)+2 种基金the National Natural Science Foundation of China(52303156)the Fundamental Research Funds for the Central Universities(XJS221301)Guangdong Provincial Key Laboratory Program(2021B1212040001)。
基金The work was supported by the National 973 projects of China(No.2015CB654603)the National Natural Science Foundation of China(No.61471290,61631166004).
文摘Dielectrics used for energy storage are highly desired for power electronics and pulse power applications and the polymer capacitors are the main commercial ones available.The development of flexible electronics and wearable devices require the relative materials being flexible.Besides,high temperature resistance is also desired because of the rising demand for high power devices and large electricity under elevated temperature.The polymer dielectrics for polymer capacitors are flexible but with relatively low working temperature normally less than 100℃.Therefore,fabricating a dielectric material to satisfy the flexibility and high working temperature simultaneously is still a great challenge.Here we propose one solution by demonstrating a hand-exfoliated fluorophlogopite film with micrometer scale thickness.Among which,the mica film with a thickness of around 10μm(Mica-10)exhibits the inorganic-like temperature stability even polymer-like flexibility.From 25℃to 200℃,Mica-10 has an energy density of around 11.27 J/cm^(3)with a variation within 2%,accompanied by a charge-discharge efficiency of around 95%at an electric field of 500 MV/m.Meanwhile,the thin thickness makes Mica-10 flexible,enabling its excellent flexibility and durability.This work revives the traditional material,mica,providing a way for high-temperature energy storage applications.
基金This work was supported by Key Area Research Plan of Guangdong(Grant No.2020B010176001)the Shenzhen Science and Technology Program(Nos.KQTD20180411143514543 and JCYJ20180504165831308)Shenzhen DRC project[2018]1433.
文摘In this work,the(1-x)CaWO_(4)-xNa_(2)WO_(4)(x=0.1,0.2,denoted as 0.9CW-0.1NW and 0.8CW-0.2NW,respectively)ultralow-loss microwave dielectric ceramics were prepared via solid-state reaction method.Using low melting-point Na_(2)WO_(4) as sintering aid to prepare CaW_(O4)eNa_(2)WO_(4) composite ceramics,the sintering temperature of CaWO_(4) was successfully reduced while maintaining excellent microwave performance.The optimal microwave dielectric properties have been achieved at 900C for 0.9CW-0.1NW ceramic:εr=9.0,Q×f=105660 GHz,tandδ=1.1×10^(-4)and tf=35.4 ppm/℃ at a frequency of 12.0 GHz.For the 0.8CW-0.2NW ceramic,the optimal microwave dielectric properties have been obtained at 740C,withεr=8.5,Q×f=97014 GHz,tandδ=1.2×10^(-4)and tf=37.4 ppm/℃ at a frequency of 11.8 GHz.In summary,both composite ceramics exhibit low sintering temperatures,excellent dielectric properties and chemical compatibility with the Ag electrode.The findings of this study provide an effective approach to prepare novel composite ceramics as promising candidates for LTCC applications.