Ultralow Interfacial Thermal Resistance of Graphene Thermal Interface Materials with Surface Metal Liquefaction

Developing advanced thermal interface materials(TIMs)to bridge heat-generating chip and heat sink for constructing an efficient heat transfer interface is the key technology to solve the thermal management issue of high-power semiconductor devices.Based on the ultra-high basal-plane thermal conductivity,graphene is an ideal candidate for preparing high-performance TIMs,preferably to form a vertically aligned structure so that the basal-plane of graphene is consistent with the heat transfer direction of TIM.However,the actual interfacial heat transfer efficiency of currently reported vertically aligned graphene TIMs is far from satisfactory.In addition to the fact that the thermal conductivity of the vertically aligned TIMs can be further improved,another critical factor is the limited actual contact area leading to relatively high contact thermal resistance(20-30 K mm^(2) W^(−1))of the“solid-solid”mating interface formed by the vertical graphene and the rough chip/heat sink.To solve this common problem faced by vertically aligned graphene,in this work,we combined mechanical orientation and surface modification strategy to construct a three-tiered TIM composed of mainly vertically aligned graphene in the middle and micrometer-thick liquid metal as a cap layer on upper and lower surfaces.Based on rational graphene orientation regulation in the middle tier,the resultant graphene-based TIM exhibited an ultra-high thermal conductivity of 176 W m^(−1) K^(−1).Additionally,we demonstrated that the liquid metal cap layer in contact with the chip/heat sink forms a“liquid-solid”mating interface,significantly increasing the effective heat transfer area and giving a low contact thermal con-ductivity of 4-6 K mm^(2) W^(−1) under packaging conditions.This finding provides valuable guidance for the design of high-performance TIMs based on two-dimensional materials and improves the possibility of their practical application in electronic thermal management.

Structural evolution of Pt‐based oxygen reduction reaction electrocatalysts

The commercialization of proton exchange membrane fuel cells(PEMFCs)could provide a cleaner energy society in the near future.However,the sluggish reaction kinetics and harsh conditions of the oxygen reduction reaction affect the durability and cost of PEMFCs.Most previous reports on Pt-based electrocatalyst designs have focused more on improving their activity;however,with the commercialization of PEMFCs,durability has received increasing attention.In-depth insight into the structural evolution of Pt-based electrocatalysts throughout their lifecycle can contribute to further optimization of their activity and durability.The development of in situ electron microscopy and other in situ techniques has promoted the elucidation of the evolution mechanism.This mini review highlights recent advances in the structural evolution of Pt-based electrocatalysts.The mechanisms are adequately discussed,and some methods to inhibit or exploit the structural evolution of the catalysts are also briefly reviewed.

In-situ monitoring of dynamic behavior of catalyst materials and reaction intermediates in semiconductor catalytic processes

Semiconductor photocatalysis, as a key part of solar energy utilization, has far-reaching implications for industrial, agricultural, and commercial development. Lack of understanding of the catalyst evolution and the reaction mechanism is a critical obstacle for designing efficient and stable photocatalysts. This review summarizes the recent progress of in-situ exploring the dynamic behavior of catalyst materials and reaction intermediates. Semiconductor photocatalytic processes and two major classes of in-situ techniques that include microscopic imaging and spectroscopic characterization are presented. Finally, problems and challenges in in-situ characterization are proposed, geared toward developing more advanced in-situ techniques and monitoring more accurate and realistic reaction processes, to guide designing advanced photocatalysts.

太阳能驱动的界面蒸发

太阳能驱动蒸发作为一种普遍存在的太阳能-热能转换过程,由于其具有较高的太阳能转换效率和巨大的工业化潜力,引起了人们的极大关注。近年来,太阳能驱动的界面蒸发通过将太阳能转化为空气/液体界面的局部化,被认为是一种有前途的替代传统的大体积加热蒸发的方法,有可能减少热损失,提高能量转换效率。

A review of microwave-metal discharge interaction:Mechanism,regulation,and application for synthesis of nanomaterials

Placing metals within microwave ovens has been generally viewed as a dangerous practice because of occurrence of violent discharge,but in recent years such discharge phenomenon has attracted increasing attention and has enabled a variety of exciting applications.In this work,we provide a comprehensive review of fundamental understanding of microwave-metal discharge interaction and its state-of-the-art application for nanomaterials synthesis.We introduce the microscopic interaction between different categories of materials and the electric and magnetic field of microwaves.For microwave-metal interaction,we highlight its size-dependence and point out the influence of the oxide layer on the surface of metals.We discuss the required conditions for occurrence of discharge,microscopic formation mechanism,and characteristic features of microwave-metal discharge processes.Through analyzing the influence from the microwave input,discharging metals,and surrounding discharging media,we discuss the strategy for systematical regulation of the discharge process.We describe the applications of the microwave-metal discharge for facile synthesis of various functional nanomaterials including core-shell carbon/metal,metal oxides,metal chalcogenides,intermetallic compounds,metallic nanoparticles and metallic compounds,and organic compounds.Finally,the challenges in precise characterization and dynamic regulation of the discharge process as well as exciting application opportunities are discussed.

猪esr基因反转录转座子插入多态性及其与大白猪生产性能的关联性分析

雌激素受体(Estrogen receptor,esr)介导雌激素影响相关基因表达,从而调控哺乳动物的生长和繁殖机能。为了探讨esr基因的反转录转座子多态性对猪生长性能的影响,文中应用比较基因组学和生物信息学方法,预测猪esr基因的反转录转座子插入位点,采用PCR方法验证不同品种猪中插入多态性,并将该基因型与大白猪性能进行关联分析。结果显示,esr1和esr2基因验证后得到4个反转录转座子多态性位点,分别是位于esr1基因内含子2的esr1-SINE-RIP1、位于内含子5的esr1-LINE-RIP2和esr1-SINE-RIP3,以及位于esr2基因内含子1的esr2-LINE-RIP。其中esr1-SINE-RIP1的287 bp SINE插入对大白猪的活体背膘厚和100 kg体重背膘厚有显著影响(P<0.05),纯合有插入(SINE^(+/+))的活体背膘厚和100kg体重背膘厚显著高于杂合有插入(SINE^(+/-))和无插入(SINE^(-/-))型。这表明esr1-SINE-RIP1位点可作为分子标记辅助选育大白猪的背膘厚性状。