聚合物/镓基液态金属复合材料的研究及应用进展

液态金属(LM)是一种在常温下呈液态,由金属或其合金掺入改性剂复合而成的材料。由于兼具金属优秀的导电性、导热性和流体的流动性,近年来液态金属成为材料领域内的研究热点,尤其是在柔性电子应用领域备受关注。文中主要以镓基液态金属为描述对象,综述了液态金属主要特性,分析了液态金属复合材料聚合物基体的选择情况,介绍了液态金属柔性电子材料的制备方法以及主要应用背景。最后,总结了液态金属的研究现状并展望了未来的发展前景与面临的挑战。

防穴蚀微胶囊/环氧树脂涂料的制备及涂层结构

以甲基丙烯酸甲酯(BMA)、甲基丙烯酸丁酯(MMA)的共聚物为壁材、聚丙烯酰胺(PAM)水溶液为芯材,采用原位聚合法合成防穴蚀微胶囊,并将其加入环氧树脂中制成防穴蚀涂料。探究了硬度、附着力、抗冲击性、拉伸强度、最大吸水率等涂层力学性能的影响因素;采用磁致伸缩振动实验研究了涂料防穴蚀性能。结果表明,随着微胶囊用量及涂层厚度的增加,涂层防穴蚀性能提升但力学性能呈下降趋势。在此基础上,设计了一种新型结构涂层,即从涂层内部到表面,微胶囊含量由0%递增至5%,对比微胶囊均匀分布的涂层结构,新型涂层结构在力学性能和防穴蚀效果上均有显著提升。

自修复抗穴蚀微胶囊的制备及性能表征

探究了W/O乳液自由基原位聚合制备以聚丙烯酰胺(PAM)水溶液为芯材、甲基丙烯酸酯树脂共聚物P(MMA-co-BMA)为壁材的自修复抗穴蚀微胶囊的方法。采用热重分析、红外光谱、扫描电镜等手段对自修复抗穴蚀微胶囊进行了性能分析和形貌表征。结果表明,此方法能合成P(MMA-co-BMA)包覆PAM水溶液微胶囊,其粒径约为40μm,包覆率达到70%以上。通过改变P(MMA-co-BMA)中甲基丙烯酸甲酯(MMA)、甲基丙烯酸丁酯(BMA)的共聚比例,制备出具有不同自修复抗穴蚀行为的微胶囊,将其添加到环氧树脂基体中固化,通过超声磁致振动装置定量表征了改性环氧树脂的失重性能。实验结果表明,PAM水溶液微胶囊具有自修复抗穴蚀性能,当BMA、MMA共聚比例为2.5∶7.5时,微胶囊抗穴蚀性能最佳。

聚乙烯醇泡沫吸水性及所含结合水和自由水的测定

为了进一步研究聚乙烯醇(PVA)泡沫的吸水机理,拓宽PVA泡沫的使用领域,对PVA泡沫进行吸水性实验,并在氧弹量热法测定物质燃烧热的基础上,利用热容的概念,测定了饱和吸水PVA泡沫中结合水和自由水的比例。结果表明,干态PVA泡沫具有较好的吸水性和保水性,吸水率为5.01 g/g、保水率为95.52%,吸水速率和缓释速率良好;其在饱和吸水状态结合水含量为20.14%,自由水含量为79.86%,相对误差0.238%。

Force-driven moisture-mediated CsPbBr_(3)nanocrystallization from amorphous glass

While the“amorphous to crystalline”transformation process,which has significant potential for application,has been widely studied,the microscopic mechanism on the nanometer scale is not fully understood.In contrast to common heat-driven phase transformations,the present study demonstrated the force-driven moisture-mediated nanocrystallization of perovskite CsPbBr_(3)precipitated from a glass matrix.In the present case,the breakage of the glass network under shearing force produces high-energy sites to absorb H2O molecules/clusters from ambient moisture,and the hydration process promotes the crystallization process.Microscratch analysis combined with confocal laser scanning microscopy revealed that the distribution of CsPbBr_(3)nanocrystals almost reproduced that of the localized stress field and clearly reflected the crack propagation pathways.The potential applications of perovskite glass in the optical sensing of force and moisture are also explored.Our findings provide insight into crystal nucleation/growth in glass,as well as understanding the dynamics of crack propagation during the brittle fracture process.

Highly crystalline Y_(3)Al_(5)O_(12):Ce^(3+)phosphor-in-silica glass ceramics for high-power solid-state lighting

The pursuit of high-brightness solid-state lighting(SSL)stimulates the development of all-inorganic color converters with high robustness.It is required that the fluorescent material is able to cope with the extreme condition generated from the irradiation of high-power-density excitation light.As such,in this work,we developed a new composite color converter,i,e.,Y_(3)Al_(5)O_(12):Ce^(3+)phosphor-in-silica glass ceramic(YAG:Ce^(3+)PiSGC).Remarkably,the amorphous SiO_(2)matrix spontaneously transforms into tetragonal SiO_(2)crystallites during co-sintering with crystallization fraction reaching up to>90%(almost full ceramization).The activation energy for crystallization E_(c)and Avrami index n of amorphous silica oxide are 298.5 kJ/mol and 1.71,indicating the diffusion-controlled glass crystallization mechanism.The fabricated prototype high-power phosphor-converted white light-emitting diode(pc-wLED)and phosphor-converted white laser diode(pc-wLD)based on YAG:Ce^(3+)PiSGC show satisfactory photometric/colorimetric parameters.The developed color co nverters have combined merits of environmental protection property,cost-effective manufacturing,good luminescent performance,and easy scalability.This study highlights a new kind of opto-functional composite material and its application as an efficient color converter in high-power solid-state lightings.

Stress-induced CsPbBr3 nanocrystallization on glass surface:Unexpected mechanoluminescence and applications

In this work,we discovered an unexpected mechanoluminescence (ML) phenomena occurring when transforming amorphous into crystalline,due to the stress-induced precipitation of CsPbBr3 perovskite nanocrystals on glass surface.It is revealed that,unlike the conventional thermal-induced phase transformation mechanism,the breakage of bonding of glass network provides the energy for nucleation and growth,and the shear stress avoids the long-range migration of structural units for crystallization.Such unique ML phenomenon enables the visualization of dynamical force that is inaccessible by common strategy,and so,opens up some novel applications,such as the pressure-sensitive "glassy pencil" to learn people's writing habits,and the pb^2+-detection with good sensitivity and selectivity.These findings not only demonstrate an effective route for the preparation of perovskite materials in a green,time-saving,low cost,and scalable way,enrich the knowledge of glass crystallization mechanism,but also exploit a useful avenue to quantitatively visualize the dynamical force.

High-security-level multi-dimensional optical storage medium:nanostructured glass embedded with LiGa_(5)O_(8):Mn^(2+) with photostimulated luminescence

The launch of the big data era puts forward challenges for information preservation technology,both in storage capacity and security.Herein,a brand new optical storage medium,transparent glass ceramic(TGC)embedded with photostimulated LiGa5O8:Mn2+nanocrystals,capable of achieving bit-by-bit optical data write-in and read-out in a photon trapping/detrapping mode,is developed.The highly ordered nanostructure enables light–matter interaction with high encoding/decoding resolution and low bit error rate.Importantly,going beyond traditional 2D optical storage,the high transparency of the studied bulk medium makes 3D volumetric optical data storage(ODS)possible,which brings about the merits of expanded storage capacity and improved information security.Demonstration application confirmed the erasable-rewritable 3D storage of binary data and display items in TGC with intensity/wavelength multiplexing.The present work highlights a great leap in photostimulated material for ODS application and hopefully stimulates the development of new multi-dimensional ODS media.

睾丸结核的临床与超声影像学特征分析

目的探讨睾丸结核的临床及超声影像学特征。方法回顾性分析2013年1月至2020年10月西藏自治区人民医院37例临床诊断为睾丸结核的患者的临床及超声影像学资料,总结其特征。结果37例患者中单侧睾丸结核26例,双侧睾丸结核11例。临床症状以阴囊肿大、慢性肿胀疼痛为主。超声检查表现多样,以片状低回声及混合回声(17/37,45.9%)、粟粒样结节(18/37,48.6%)、结节或肿块(6/37,16.2%)、窦道形成(8/37,21.62%)为主要超声表现,部分患者可多种征象并存。32例患者同时伴发附睾结核声像图改变,表现为附睾弥漫性增大、结节或脓肿。结论睾丸结核的临床表现及超声声像图表现多样。详细了解相关病史,熟练掌握其超声声像图特征及鉴别诊断要点,有助于做出正确诊断。

Patterned glass ceramic design for high-brightness high-color-quality laser-driven lightings

Up-to-date laser-driven lightings confront a challenge of simultaneously achieving good photometric and chromatic performances.Herein,the coupling of“patterned package design”and“phosphor wheel”was proposed and demonstrated effectively to deal with this tough issue,based on a new architecture of CaAlSiN3:Eu2+(CASN:Eu)glass ceramic film(GCF)on Y_(3)Al_(5)O_(12):Ce^(3+)(YAG:Ce)GC plate.The fabricated composite has no interface between the two functional layers and retains the admirable luminescent features from CASN:Eu and YAG:Ce for the microstructural integrity during co-sintering.The studies on laser-microcrystalline interactions reveal that the luminescence saturation is almost determined by thermal quenching for YAG:Ce,but is ascribed to thermal/intensity quenching which are equally crucial for CASN:Eu.Benefiting from the elaborate architecture design,good color chromaticity tunability was obtained,and severe photon reabsorption was reduced.Moreover,accompanied with the rotation induced increase of thermal convection to air and pulse-like excitation,the constructed lighting engine under blue laser driven shows bright white light with luminous flux(LF)higher than 1000 lm,adjustable chromaticity from cool to warm,and improved color rendering index(CRI)approaching to 70.

Boosting single-band red upconversion luminescence in colloidal NaErF_4 nanocrystals:Effects of doping and inert shell

Single-band red upconversion luminescence(UCL) is vital to in vivo bioimaging as well as "see and treat" biomedicines. Herein, starting with the previously reported β-NaErF4:Tm UCNPs, we examined the effects of both Yb^(3+) doping and inert shell coating on the red-to-green(R/G) ratio for Er3+ based UCL. The doping of Yb^(3+) into the β-NaErF4:Tm3+ core not only enhances the whole UCL intensity, but also raises the R/G ratio by 1.25 times. In addition, the coating of an inert NaYF4 shell, which is usually adopted for the enhancement of UCL intensity, further boosts the R/G value up to as high as 77.92. This work may benefit the potential bioimaging application of single-band red UCL.

Enhanced performance of a fast GaAs-based terahertz modulator via surface passivation

Surface-modified semiconductors show enormous potential for opto-terahertz(THz)spatial modulation due to their enhanced modulation depth(MD)along with their inherent broad bandwidth.Taking full advantage of the surface modification,a performance-enhanced,all-optical,fast switchable THz modulator was achieved here based on the surface-passivated Ga As wafer.With a decreased surface recombination rate and prolonged carrier lifetime induced by passivation,S-passivated Ga As was demonstrated as a viable candidate to enhance THz modulation performance in MD,especially at low photodoping levels.Despite a degraded modulation rate owing to the longer carrier lifetime,this passivated Ga As modulator simultaneously realizes a fast modulation at a 69-MHz speed and as high an MD as ~94% in a spectral wideband of 0.2-1.2 THz.The results demonstrated a new strategy to alleviate the tradeoff between high MD and speed in contrast to bare surfaces or heterogeneous films/unusual geometry on semiconductors including Si,Ge,and GaAs.