Mesenchymal stem cell-derived exosome:The likely game-changer in stem cell research

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.

High energy density and superior charge/discharge efficiency polymer dielectrics enabled by rationally designed dipolar polarization

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.

受章鱼启发的柔性红外变色材料

在红外波段模拟章鱼皮肤变色功能的柔性材料在智能热管理、柔性显示和自适应伪装等领域具有广泛的应用前景.本文利用液态金属颗粒和柔性弹性体模拟头足纲变色动物皮肤中的色素细胞和真皮基质,开发了一种通过机械变形调控红外反射/辐射性能的“全柔性红外变色皮肤”.在等轴拉伸作用下,液态金属颗粒会伴随弹性体基体发生延展/收缩变形,从而改变其外形、尺寸和表面形貌,实现对材料红外反射率和发射率的动态调控,以达到动态伪装效果.实验证明,集成了液态金属颗粒/弹性体复合材料的柔性多步态机器人能够在运动过程中迅速改变体色,并且在高次数循环中展现出优异的机械稳定性.本研究为未来设计新型红外发射率动态可调材料与器件提供了材料和物理基础.

Tunable natural resonances via synergistic effects of two phases in Fe_(x)(Co_(y)Ni_(1-y))_(100-x)for multi-band microwave absorption

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.

厌氧E-MBR反应器在焦化废水处理中的微生物特性研究

【目的】将厌氧的膜生物反应器(MBR)与微生物燃料电池(MFC)耦合的厌氧电辅助膜生物反应器(E-MBR)应用于实际工业焦化废水处理。【方法】通过正交实验优化了反应器进水的培养条件为PO_(4)^(3-)14.3 mg/L、Fe^(2+)0.2 mg/L、Fe^(3+)0.1 mg/L、Co^(2+)0.1 mg/L和Mn^(2+)0.2 mg/L。在此条件下考察了该反应器对系统中有机污染物的去除效率及厌氧污泥的污泥特性、产电性能、胞外聚合物(EPS)、微生物群落结构及膜污染的影响。【结果】结果表明,与未优化的培养条件相比,工业焦化废水COD的去除率提高了23%;污泥浓度(MLSS)、比重、沉降速度增加,污泥体积指数(SVI)降低,表明污泥颗粒化及沉降性能提高;污泥中溶解性EPS(SMP)、松散态EPS(LB-EPS)及紧密结合态EPS(TB-EPS)这3种组分中的蛋白质与多糖的比例(P/C)分别降低0.12、0.25和0.16,表明污泥更易于被降解;厌氧污泥的产电性能增强;高通量分子测序结果表明,反应器中污泥的群落结构发生了明显的变化,优势菌群突出;经扫描电镜(SEM)对比结果表明,反应器阴极膜的污染情况也得到了一定的减缓。【结论】优化进水培养条件可以达到使反应器污水处理效率提高、清理周期缩短和运行更稳定等效果,对于工业废水处理技术的节能环保方面提供一定的理论依据。

Flexible mica films for high-temperature energy storage

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.

Ultralow-loss (1-x)CaWO_(4)-xNa_(2)WO_(4) (x=0.1,0.2) microwave dielectric ceramic for LTCC applications

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.